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HomeMy WebLinkAboutSDP 2018-0022; RESORT VIEW APARTMENTS; GEOTECHNICAL UPDATE EVALUATION; 2019-02-04GEOTECHNICAL UPDATE EVALUATION RESORT IE-W APA TMENT-S-;-VIEJ~CASfll:l:A'\WAY CAR,t:S ORN-fA ASSE & -15 • ____ L T,LL 2800 VIA DEL RIO YORBA LINDA, CALIFORNIA 92877 W .0. 7535-A-SC FEBRUARY 4, 2019 • Geotechnical • Geologic • Coastal • Environmental 5741 Palmer Way • Carlsbad, California 92010 • (760) 438-3155 • FAX (760) 931-0915 • www.geosoilsinc.com February 4, 2019 BNR Investment and Development, LLC 28000 Via Del Rio Yorba Linda, California 92887 Attention: Mr. Ram Setya W.O. 7535-A-SC Subject: Geotechnical Update Evaluation, Resort View Apartments, Viejo Castilla Way, Carlsbad, San Diego County, California, Assessor's Parcel Numbers (APNs) 216-170-14 &-15 Dear Mr. Setya: In accordance with your request and authorization, GeoSoils, Inc. (GSI) is pleased to present the results of our geotechnical update evaluation of the subject site. The purpose of our study was to supplement a previous onsite investigation GSI performed in 2003 (GSI, 2003a and 2003b [see Appendix A]), in light of new information GSI has recently obtained regarding the pre-graded topographic conditions within the parcels. This geotechnical update also addresses the currently proposed development shown on the architectural and preliminary grading plans prepared by Foxlin Architects ([FA], 2018) and MLB Engineering ([MLB], 2018), and brings our previous geotechnical work into conformance with the relevant 2016 California Building Code ([2016 CBC], California Building Standards Commission [CBSC], 2016). Unless specifically superseded herein, the conclusions and recommendations contained in GSI (2003a and 2003b) are still considered valid and applicable, and should be appropriately implemented during project planning, design, and construction. EXECUTIVE SUMMARY Based upon our field exploration, geologic, and geotechnical engineering analysis, the proposed residential development appears feasible from a geotechnical viewpoint, provided that the recommendations presented in the text of this report are properly incorporated into the design and construction of the project. The more significant aspects of our evaluation are: • Based on our review and recent, and previous (GSI, 2003b) site work, approximately two-thirds of the subject property is mantled by existing artificial fill placed in 1969 under the purview of Benton Engineering, Inc. ([BEi], 1969). The fill materials where predominately placed within a northerly to northwesterly trending natural drainage channel in order to bring the site to current grades. Elsewhere, Quaternary-age stream terrace deposits occur in the near-surface and are discontinuously mantled by Quaternary-age colluvium (topsoil). Quaternary-age alluvium was encountered underlying the existing fill in Boring B-1, which was recently advanced near the axis of the former drainage channel in the vicinity of the northerly property boundary. • Laboratory tests indicate that the existing fill materials are non-uniform relative to density and degree of saturation. Records indicate (Appendix A) that these materials were placed almost 50 years ago under a different compaction standard. Consolidation tests indicate the existing fill materials exhibit between 4.6 and 7.4 percent hydrocompression when subjected to loads up to 8,000 pounds per square foot (psf.). Further, as observed in Boring B-1, advanced near the center of the northerly property boundary, the fill appears to have been placed on left-in-place or partially reprocessed alluvial materials that are saturated and soft. Lastly, based on our review of BEi (1969), there is no documentation of the placement of a subdrain in the bottom of the in-filled drainage channel. Although infilled, this natural drainage channel remains a preferential pathway for groundwater. Thus, the lower section of the existing fill could be subjected to periodic wetting from perched groundwater, and undergo hydrocompression in response to additional fill or foundation load. • A review of MLB (2018) and the existing subsurface data indicates that proposed Buildings "A," "C," and "E" are predominately underlain by compressible existing fill materials and a localized area of left-in-place and/or reprocessed alluvium. Whereas, proposed Buildings "B" and "D" are largely underlain by stream terrace deposits with a thin, relatively shallow mantle of colluvium. It is likely that most if not all of the colluvium beneath the footprints of proposed Buildings "B" and "D" will be removed during the currently planned excavation. • In order to mitigate settlement of the existing fill materials under the proposed service loads, GSI recommends either limited remedial grading of the near-surface fills and the use of vibro piers (aggregate piers) to control settlement within proposed building areas, underground utility corridors, and retaining walls. Alternatively, the existing fill and any underlying alluvium should be entirely removed to expose suitable stream terrace deposits. The excavated earth materials should then be reused as compacted fill, placed under the observation and testing of GSI. The alternative to perform the complete removal and recompaction of the existing fill and any alluvial deposits would likely require shoring or slot grading along portions of the property boundaries. In addition, GSI recommends that a subdrain be installed along the axis of the natural drainage channel following remedial excavation and prior to fill placement if the complete removal and recompaction (of existing fills and alluvial materials) alternative is performed. Because there is not practical way of outletting the subdrain via gravity, a permanent sump pump would be necessary to convey the collected subsurface seepage water into the onsite storm drain system allowed by the City engineer. The maximum to minimum fill thickness beneath the proposed buildings, associated with the "full-depth" remedial grading alternative, should not exceed a ratio of 3:1 BNR Investment and Development, LLC • File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC Page Two (maximum:minimum). This may require overexcavation of stream terrace deposits and replacement fills. • For uniform support of proposed Buildings "A," "C," and "E," GSI recommends that either limited remedial grading be performed with building loads transferred into suitable stream terrace deposits via vi bro piers, or the existing fill materials and any underlying potentially compressible natural soils (i.e., alluvium, colluvium, and/or weathered stream terrace deposits) be removed and recompacted. In order to provide uniform support of proposed Buildings "B" and "D," and to help mitigate the shrink/swell effects of expansive soils and reduce the potential for post-development perched water conditions within the influence of these buildings, GSI recommends that these structures be underlain by a compacted fill blanket minimally extending to depths of 4 feet below pad grade or 24 inches below the lowest foundation element (whichever is greater). Once building foundation loads and load patterns become available, GSI can provide the areal layout of vi bro piers on the foundation plans. Additional subsurface exploration using cone penetration test (CPT) soundings may be needed to value engineer vibro pier locations/depth of treatment. Based on the available subsurface data vibro piers may extend to depths up to approximately 28½ feet below existing grade (BEG). Whereas, remedial earthwork excavations would extend to depths up to approximately 25% feet BEG. • It should be noted that any settlement-sensitive appurtenant structures such as walls, pavements (vehicular and pedestrian), light standards, etc. that are not uniformly supported by vibro piers or recompacted fills overlying unweathered, stream terrace deposits will retain the potential for settlement and associated distress. Thus, the mitigation for such should be evaluated through value engineering (i.e., costs for mitigation versus long-term maintenance, repair, and/or replacement). • Laboratory tests performed in preparation of GSI (2003b) and this update indicate that the near-surface earth materials are very low to high in expansion potential with expansion indices ranging between approximately < 10 and 91. Atterberg Limits tests performed in preparation of GSI (2003b) and this update indicate that the onsite soils have plasticity indices ranging between 25 and 36. Swell pressure testing, performed on a relatively undisturbed sample of the existing fill material, collected during our recent field exploration, indicates that a confining pressure equivalent to approximately 2,050 psf is necessary to resist swell (uplift) pressure imparted by the tested sample. Thus, some of the onsite soils meet the criteria for expansive soils, as defined in Section 1803.5.3. of the 2016 CBC (CBSC, 2016). In order to comply with 2016 CBC requirements for the mitigation of expansive soils, the proposed residential structures will require specific foundation and slab-on-grade design that will tolerate the shrink/swell effects of expansive soils (see Sections 1808.6.1 and 1808.6.2 of the 2016 CBC). Alternatively, expansive soils within the influence of the proposed residential structures (upper 10 feet) and/or associated improvements may be removed and replaced with very low expansive BNR Investment and Development, LLC • File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC Page Three soils (E.I. of 20 or less) with a P.I. of 14 or less (see Section 1808.6.3 of the 2016 CBC). The implementation of earthwork as alternative mitigation for expansive soils will require a significant amount of selective grading (i.e., mining) and/or export, and import. Thus, earthwork mitigation of expansive soils should be evaluated on a value engineering basis. Expansive soils are predominately associated with the existing fill materials, colluvium, and alluvium. The Quaternary-age stream terrace deposits are predominately granular in nature but do contain zones of fine-grained soils, which could exhibit expansive characteristics. • Laboratory tests, performed in preparation of GSI (2003a) indicate that a tested sample of the onsite soils is mildly alkaline with respect to soil acidity/alkalinity; is moderately corrosive to exposed, buried metals when saturated; and has non-detectable concentrations of soluble sulfates ("Exposure Class SO" per Table 19.3.1.1 of American Concrete Institute [ACI] 318-14) and soluble chlorides. GSI does not consult in the field of corrosion engineering. Thus, consultation from a qualified corrosion consultant may be considered based on the level of corrosion protection required for the project, as determined by the Project Architect, Structural Engineer, Civil Engineer, and Plumbing/Mechanical Engineers. Additional testing relative to the general corrosivity of soils exposed near finish grade are recommended at the conclusion of grading, prior to placement of underground utilities and foundations. • GSI did not encounter a regional groundwater table nor perched water within our previous (GSI, 2003b) and recent subsurface explorations. However, the left-in-place and/or reprocessed alluvium encountered in hollow-stem auger Boring B-1, between approximate depths of 22 and 25% feet BEG, appeared wet to possibly saturated. This suggests that ephemeral perched water may occur near the bottom of the former natural drainage course that was in-filled during the original grading of the site in 1969. The regional groundwater table is anticipated to be near sea level or approximately 70 feet below the lowest existing site elevation. Thus, the regional groundwater table is not anticipated to significantly affect proposed development of the subject site. Perched groundwater may occur along the geologic contact between the existing fill materials and the underlying Quaternary-age stream terrace deposits, owing to the permeability/density contrasts between these earth materials. Similarly, perched groundwater could occur along fill lifts and geologic discontinuities. Sources of perched water may include, but not necessarily be limited to up-gradient irrigation practices, seasonal rainfall, and/or damaged wet underground utilities. Our findings reflect the groundwater conditions at the time of the GSI (2003b) and our recent field work, and do not preclude future changes in local groundwater conditions that were not obvious, at the time of our studies. The potential for perched groundwater to be encountered both during and following site development should be disclosed to all interested/affected parties. BNR Investment and Development, LLC • File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC Page Four • On a preliminary basis, temporary slopes should be constructed in accordance with Cal-OSHA guidelines for Type "B" soil conditions provided that groundwater and running sands are not present. All temporary slopes should be observed by the geotechnical consultant during construction. If adverse conditions are exposed in temporary slopes, the slopes would need to be inclined to flatter gradients or shoring would need to be installed. Should property boundaries or existing improvements that are to remain in service limit the recommended temporary slope construction, the installation of shoring and/or slot grading would be recommended. Recommendations for the design and construction of shoring and alternating slot excavations are included in this report. • Our evaluation indicates that with the exception of moderate to strong ground shaking as a result of a regional earthquake, the proposed development has low susceptibility to be adversely affected by geologic and secondary seismic hazards, provided the recommendations, included herein, are appropriately implemented into project design and construction. • The seismic acceleration values and design parameters provided herein should be considered during the design of the proposed development. The adverse effects of seismic shaking on the structure(s) will likely be wall cracks, some foundation/slab distress, and some seismic settlement. However, it is anticipated that the proposed structures will be repairable in the event of the design seismic event. This potential should be disclosed to any owners and all interested/affected parties. • Site soils are considered erosive. Thus, properly designed and maintained site drainage is necessary in reducing erosion damage to the planned improvements. • Our field testing and analysis relative to the infiltration rates of onsite earth materials in proximity to the proposed permanent stormwater BMPs/LIDs, shown on MLB (2018), indicates that an estimated reliable infiltration rate of 0.148 in/hr may be used in the design of infiltration BMPs/LIDs. This rate supports the "partial infiltration of stormwater. However, it is our opinion that if stormwater infiltration were to occur onsite, the infiltrated water would perch upon the less permeable stream terrace deposits or fine-grained fill materials, and then migrate laterally, leading to saturation of fills and backfills, located both onsite and offsite. In response, the weakened fills and backfill could settle. In addition, wetting of expansive soils could induce heave. Both phenomena would likely contribute to improvement distress both onsite and offsite. Therefore, stormwater treatment through infiltration is not recommended at the subject site. Rather stormwater treatment should occur in contained systems (i.e., precast concrete vaults) or utilize deep infiltration, as discussed previously. • The recommendations presented in this report should be incorporated into the design and construction considerations of the project. BNR Investment and Development, LLC • File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC Page Five The opportunity to be of service is sincerely appreciated. If you should have any questions, please do not hesitate to contact our office. GeoSoils, Inc. ~!~ Engineering Geolog1 ~i Geotechnical Engine ,i~me,- Staff Geologist RBB/JPF/ATG/jh Distribution: (1) Addressee (via email) (2) Foxlin Architecture, Attn: Mr. Michael Fox (2 wet signed) (1) Kurt Fischer Structural Engineering, Attention : Mr. Kurt Fischer (via email) (1) MLB Engineering, Attention: Mr. Michael Benesh (via email) (1) Streamline Development, Attention: Mr. John Allen (via email) BNR Investment and Development, LLC • File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC Page Six TABLE OF CONTENTS SCOPE OF SERVICES ................................................... 1 SITE DESCRIPTION AND PROPOSED DEVELOPMENT ......................... 1 PROJECT GEOTECHNICAL BACKGROUND .................................. 3 RECENT SUPPLEMENTAL FIELD STUDIES .................................. 6 PHYSIOGRAPHIC AND REGIONAL GEOLOGIC SETTINGS ...................... 6 Physiographic Setting .............................................. 6 Regional Geologic Setting ........................................... 6 SITE GEOLOGIC UNITS .................................................. 7 General .......................................................... 7 Existing Artificial Fill (Map Symbol -Af) ........................... 8 Quaternary Colluvium (Not Mapped) ............................. 8 Quaternary Alluvium (Not Mapped) .............................. 8 Quaternary Stream Terrace Deposits (Map Symbol -Qst) ............ 8 Structural Geology ................................................. 9 GROUNDWATER ........................................................ 9 UPDATED GEOLOGIC/SEISMIC HAZARDS EVALUATION ...................... 10 General ......................................................... 10 Mass Wasting/Landslide Susceptibility ................................ 10 Faults and Surface Rupture ......................................... 11 Updated Seismicity ..................................................... 11 Deterministic Site Acceleration ...................................... 11 Historical Site Acceleration ......................................... 11 Seismic Shaking Parameters ........................................ 12 Secondary Seismic Hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Liquefaction/Lateral Spreading ................................. 13 Seismic Densification .............................................. 14 Summary ........................................................ 14 Other Geologic/Secondary Seismic Hazards ........................... 15 ROCK HARDNESS/EXCAVATION FEASIBILITY ............................... 15 STORM WATER INFILTRATION RATE EVALUATION AND DISCUSSION .......... 15 Subsurface Exploration ............................................ 15 United States Department of Agriculture (USDA)/Natural Resources Conservation Service (NRCS) Soil Survey ................................... 16 Infiltration Screening Feasibility ...................................... 16 GeoSoils, Inc. LABORATORY TESTING ................................................. 18 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Moisture-Density Relations ......................................... 18 Laboratory Standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Expansion Index .................................................. 19 Atterberg Limits ................................................... 19 Swell Pressure ................................................... 19 Direct Shear Test ................................................. 20 Consolidation Testing ............................................. 20 Corrosion/Sulfate Testing ........................................... 20 Corrosion Summary ......................................... 21 PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS .................... 21 EARTHWORK CONSTRUCTION RECOMMENDATIONS ....................... 26 General ......................................................... 26 Site Preparation .................................................. 26 Limited Remedial Excavation -Buildings "A," "C," and "E" and Adjacent Drive Aisles and Landscape Areas ........................................ 26 Overexcavation -Buildings "B" and "D" and Portions of Buildings "A," "C," and "E" Exposing Suitable Unweathered Stream Terrace Deposits at Pad Grade .......................................................... 27 Alternating Slot Excavations ........................................ 28 Perimeter Conditions .............................................. 28 Fill Placement .................................................... 28 Earthwork Mitigation of Expansive Soils ............................... 28 Import Soils ...................................................... 29 Graded Slope Construction ......................................... 29 General ................................................... 29 Cut Slopes ................................................. 29 Other Geotechnical Considerations ............................. 29 Temporary Slopes ................................................ 30 Excavation Observation and Monitoring (All Excavations) -All Alternatives ... 30 Observation ................................................ 31 Earthwork Balance (Shrinkage/Bulking) -All Alternatives ................. 31 GROUND IMPROVEMENT -VIBRO PIERS -BUILDING UNITS "A", "C," AND "E" ... 32 ALTERNATIVE REMEDIAL GRADING ....................................... 33 PRELIMINARY RECOMMENDATIONS -FOUNDATIONS ....................... 34 General ......................................................... 34 Shallow Foundation Design Building "A" Through "E" .................... 35 Post-Tension Foundation Systems Building Units "A" Through "E" ......... 35 Slab Subgrade Pre-Soaking ................................... 37 BNR Investment and Development, LLC • File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Table of Contents Page ii Perimeter Cut-Off Walls ....................................... 37 Post-Tension Foundation Design ............................... 37 Post-Tension Foundation Soil Support Parameters ................. 38 Mat Foundations .................................................. 39 Mat Foundation Design ....................................... 39 Slab Subgrade Pre-Soaking ........................................ 40 Perimeter Cut-Off Walls ....................................... 40 FOUNDATION AND FILL SETTLEMENT ..................................... 40 SOIL MOISTURE TRANSMISSION CONSIDERATIONS ........................ 41 RETAINING WALL DESIGN PARAMETERS .................................. 44 General ......................................................... 44 Conventional Retaining Walls ....................................... 44 Preliminary Retaining Wall Foundation Design -Shallow Foundations, Grading And Vibro Pier Mitigated Soil ...................................... 44 Additional Design Considerations .............................. 45 Restrained Walls ............................................ 45 Cantilevered Walls ........................................... 45 Seismic Surcharge ................................................ 46 Retaining Wall Backfill and Drainage .................................. 47 Wall/Retaining Wall Footing Transitions ............................... 51 SHORING DESIGN AND CONSTRUCTION .................................. 51 Shoring of Excavations ............................................. 51 Lateral Pressure .................................................. 52 Shoring Construction Recommendations .............................. 54 Monitoring of Shoring .............................................. 55 Monitoring of Structures ...................................... 56 ONSITE PRELIMINARY PAVEMENT DESIGN/CONSTRUCTION ................. 57 Structural Section ................................................. 57 Pavement Grading Recommendations ................................ 59 General ................................................... 59 Subgrade .................................................. 59 Aggregate Base .................................................. 59 Paving .......................................................... 59 Drainage ........................................................ 60 PCC Cross Gutters ................................................ 60 Additional Considerations .......................................... 60 PEDESTRIAN PAVEMENTS/FLATWORK AND OTHER IMPROVEMENTS .......... 60 BNR Investment and Development, LLC • File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Table of Contents Page iii ONSITE INFILTRATION-RUNOFF RETENTION SYSTEMS ...................... 63 General ......................................................... 63 DEVELOPMENT CRITERIA ............................................... 65 Slope Deformation ................................................ 65 Slope Maintenance and Planting ..................................... 65 Drainage ........................................................ 66 Erosion Control ................................................... 66 Landscape Maintenance and Planter Design ........................... 67 Gutters and Downspouts ........................................... 67 Subsurface and Surface Water ...................................... 67 Site Improvements ................................................ 68 Tile Flooring ..................................................... 68 Additional Grading ................................................ 68 Footing Trench Excavation ......................................... 68 Trenching/Temporary Construction Backcuts .......................... 69 Utility Trench Backfill .............................................. 69 SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING ........................................................ 70 OTHER DESIGN PROFESSIONALS/CONSULTANTS .......................... 71 PLAN REVIEW ......................................................... 71 LIMITATIONS .......................................................... 72 FIGURES: Figure 1 -Site Location Map ......................................... 2 Detail 1 -Typical Retaining Wall Backfill and Drainage Detail .............. 48 Detail 2 -Retaining Wall Backfill and Subdrain Detail Geotextile Drain ....... 49 Detail 3 -Retaining Wall and Subdrain Detail Clean Sand Backfill ........... 50 Figure 2 -Lateral Earth Pressures for Temporary Shoring ................. 53 ATTACHMENTS: Appendix A -References ................................... Rear of Text Appendix B -Boring and Test Pit Logs ........................ Rear of Text Appendix C -Updated Seismicity ............................ Rear of Text Appendix D -Infiltration Test Data and Worksheets .............. Rear of Text Appendix E -Laboratory Test Data ........................... Rear of Text Appendix F -General Earthwork, Grading Guidelines, and Preliminary Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rear of Text Plate 1 -Geotechnical Map . . . . . . . . . . . . . . . . . . . . . . . . . Rear of Text in Folder Plate 2 -Geologic Cross Sections A-A' & B-B' . . . . . . . . . . Rear of Text in Folder BNR Investment and Development, LLC • File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Table of Contents Page iv GEOTECHNICAL UPDATE EVALUATION RESORT VIEW APARTMENTS, VIEJO CASTILLA WAY CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA ASSESSOR'S PARCEL NUMBERS (APNs) 216-170-14 & -15 SCOPE OF SERVICES The scope of our services has included the following: 1. A review of existing site-specific geotechnical reports, former grading plans, and readily available published geologic maps of the vicinity (Appendix A); 2. Supplemental surficial mapping and subsurface exploration with nine (9) hollow-stem auger borings advanced with a truck-mounted drill rig (Appendix B); 3. Updating site seismicity and seismic hazards in accordance with the 2016 California Building Code (Appendix C); 4. Percolation testing in borings advanced in the vicinity of proposed permanent storm water best management practices/low impact development (BMPs/LIDs) to establish preliminary soil infiltration rates (Appendix D); 5. Laboratory testing of relatively undisturbed and representative bulk soil samples collected during the supplemental subsurface exploration program (Appendix E); 6. Geotechnical engineering analyses; and 7. Preparation of this summary report and accompaniments. SITE DESCRIPTION AND PROPOSED DEVELOPMENT The subject site consists of two previously graded, vacant, parcels of land along the westerly side of Viejo Castila Way, approximately 30 feet northerly of the Viejo Castilla Way and Pirineos Way intersection in Carlsbad, San Diego County, California (see Figure 1, Site Location Map). The geographic coordinates of the approximate centroid of the study area are 33.0882, -117.2519. The property is bounded by Viejo Castilla Way to the east, by a golf course to the south, and by developed residential properties to the remaining quadrants. Topographically, the site slopes to the northeast at gradients on the order of 2½:1 (horizontal:vertical [h:v]) or flatter. According to MLB Engineering (MLB, 2018), site elevations range between approximately 69 and 90 feet (North American Vertical Datum of 1988 [NAVD88]) for an overall relief of approximately 21 feet. Site drainage appears to be accommodated by sheet-flow runoff which follows the current site topography to the northeast. Vegetation consists of weeds, grasses, and sparse to locally abundant trees. GeoSoils, Inc. SITE --------- Base Map: TOPO!® ©2003 National Geographic, U.S.G.S. Encinitas, California --San Diego Co., 7.5 Minute, dated 1997, current, 1999. 0mm ~a Costa f Reso Spa LA COSTA San Mar~ Cree.~ ,/ La Costa n rl ppmg Center Y La co Green Valley 'i, 1ig•Way ..q~cante Rd Via DeForruna SITE La Costa Canyon Park ff ,; OQIRe,,~.,e NOTTO SCALE Base Map: Google Maps, Copyright 2019 Google, Map Data Copyright 2019 Google This map Is copyrighted by Google 2019. It Is unlawful to copy or reproduce all or any part thereof, whether for personal use or resale, without permission. All rights reserved. N ~-w.o. 7535-A-SC SITE LOCATION MAP Figure 1 Based on our review of Foxlin Architects (FA, 2018) and MLB (2018), GSI understands that the currently proposed site development includes preparing the site to receive five (5), apartment buildings with associated underground utilities, pavements, and walls. MLB (2018) indicates that cut and fill grading will be conducted to achieve the design grades, with maximum planned cuts and fills on the order of 11 feet and 2 feet, respectively. Grade transitions will primarily be accommodated by the construction of retaining walls with a maximum height of approximately 11 feet. FA (2018) shows that the proposed buildings will consist of three (3) to four (4) floor levels. However, FA (2018) shows that the northernmost building (Building "E") will include a roof deck. GSI anticipates that the proposed residential structures will consist of a combination of wood frame and masonry construction with slab-on-grade floors. Building loads are currently unknown, but assumed to be typical for similar multi-family residential development. Sanitary sewage disposal is anticipated to be connected into the existing municipal system. MLB (2018) indicatesthatonsite storm water will sheet flow toward area drain inlets that in turn, collect the runoff and convey it to infiltration trenches in the two (2) drive aisles. The infiltration trenches will be 80 to 92 feet in length, 9 feet wide, and 5 feet deep. The trenches will include two (2) 42-inch diameter perforated drain pipes positioned side-by-side in plan view that are encased in ¾-inch clean gravel. MLB (2018) shows the tops and sides of the trenches will receive a 10-mil plastic sheeting (visqueen). PROJECT GEOTECHNICAL BACKGROUND Based on our review of the original grading plan (McIntire & Quiros, Inc. [M&Q], 1968), the subject parcels are Lots 35 and 36 of Unit No. 1 , within the La Costa-South subdivision. This plan shows that the former (pre-grade) topography at the subject site primarily consisted of a relatively narrow, northerly to northwesterly trending natural drainage course that flowed toward nearby La Costa Creek. M&Q (1968) indicate that the former existing grades within the subject site ranged between approximately 52 feet and 89 feet above sea level (unknown datum). A comparison of the former existing grades on M&Q (1968) to the current existing grades shown on MLB (2018) suggest that the original grading of the parcels involved maximum planned cuts and fills on the order of 14 feet and 18 feet respectively. The deepest cut was performed near the northeasterly corner of Lot 36 and the deepest fill occurred along the northerly property line of this lot, approximately 54 feet westerly of its northwesterly property corner. Our review of existing geotechnical reports prepared by Benton Engineering, Inc. ([BEi], 1968 and 1969) indicates that a preliminary investigation of Unit No. 1 of the La Costa-South subdivision was performed in 1968. This study included the excavation and logging of three (3) borings, advanced with a truck-mounted bucket-auger drill rig and seven (7) test pits completed with a backhoe. A map showing the locations of BEi's BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 3 subsurface explorations was reported to be included in their summary report (BEi, 1968); however, this map was not included with the report copy reviewed by GSI. Therefore, it is unknown if any of BEi's subsurface explorations were completed within the subject site. As part of their preliminary study, BEi also performed laboratory testing of soil samples they collected during their field work. Based on their field work and laboratory testing, BEi concluded that the natural soils were generally suitable for supporting new fills and residential structures. However, they stated that the upper portion of alluvium encountered in some of the natural drainage course within the subdivision were relatively soft or loose; and therefore, not capable of supporting applied loads. Therefore, they recommended the removal and reuse of these earth materials as compacted fill with remedial excavations generally extending between 1.2 feet and 6 feet below the former, existing grades. BEi also concluded that some of the soils within the subdivision exhibited expansion potentials that would require the use of specialized foundations and slab-on-grade floors in order to mitigate the damaging shrink/swell effects of these earth materials. In BEi (1969), BEi presented a summary of their observations and testing during compacted fill placement within Unit No. 1 of the La Costa-South subdivision. As reported therein, the placement of compacted fills, within the subdivision, occurred between February 4, and May 2, 1969. Based on their observations and field density testing, BEi concluded that the placed fill materials were compacted to at least 90 percent of the maximum dry density (per ASTM D 1557-66T and can provide a "safe" bearing pressure of at least 1,51 0 pounds per square foot for a 1-foot wide continuous footing constructed no closer than 5 feet from the tops of descending slopes. However, BEi (1969) only states that the aforementioned bearing value can be attained at a "minimum depth" but does not report the depth dimension. BEi further concluded that the, "compacted filled ground is adequate to satisfactorily support" one-and two-story, wood-frame residential structures without detrimental settlements. According to BEi's "Table of Test Results," nine (9) field density tests were conducted on compacted fills placed within the subject parcels. This table indicated that the maximum depth of the tested fill was 23 feet, and that the onsite, existing fills were compacted to between 90.5 and 94.8 percent of the maximum dry density (per ASTM D 1557-66T), with field moisture contents ranging between 12.3 and 16.4 percent. It should be noted that GSI could not locate the laboratory proctors used to compare against the results of two (2) of their field density tests. BEi (1969) also reported that compacted fills in the upper 3 feet of the subject site were expansive. To that end, BEi recommend that residential structures constructed within Lots 35 and 36 include specialized foundation and slab-on-grade floor systems to provide protection from shrink/swell effects. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 4 In late 2003, GSI performed a preliminary geotechnical evaluation of the subject site for a previous multi-family residential development concept. For this study, we logged four (4) exploratory test pits, excavated with a backhoe; performed laboratory testing on soil samples collected from the test pits; evaluated risks to geologic/seismic hazards; performed engineering analyses; and prepared a summary report and an addendum presenting our findings, conclusions, and recommendations (GSI, 2003a and 2003b). In GSI (2003b), we reported that the eastern and northern portions of the site were mantled by undocumented fill with thicknesses on the order of 1 foot to 2 feet. Near the northwesterly and southeasterly corners of the site, the fill was directly underlain by approximately½ foot to 2 feet of colluvium (topsoil). Near the north-central portion of the site, the fill was underlain by stream terrace deposits belonging to the Quaternary-age Sweitzer Formation. Near its southwesterly corner, we found that site was mantled by approximately 1 foot of colluvium, underlain by the aforementioned formational earth materials. The fill materials encountered during our subsurface exploration were reported to be undocumented because at the time of our study, we were not aware of BEi (1969). Groundwater was not encountered in the subsurface explorations to the explored depths (i.e., approximately 4 feet to 10 feet below the existing grades). Reviews of in-house geologic literature and maps did not indicate the site to be at significant risk to geologic/secondary seismic hazards. However, owing to its locations within an active seismic region, we concluded that the site would be subject to ground shaking resulting from earthquakes on any of a number of regionally active faults. Laboratory testing relative to expansion potential and plasticity indicated soils with very low to high expansion potentials. Our tests showed expansion indices ranging between 1 and 91 , and a plasticity index of 33. Based on our subsurface and laboratory findings, we then concluded that the site was suitable for the then-proposed residential development. However, we recommended that all undocumented fills, colluvium, and weathered stream terrace deposits be removed to expose relatively unweathered stream terrace deposits and then be reused as fills materials compacted to at least 90 percent on the laboratory standard (ASTM D 1557). GSI also provided recommendations for building foundation and slab-on-grade floor systems in light of the expansion potentials exhibited by the onsite earth materials. Recommendations for shoring were also provided if there was insufficient space to conduct remedial and planned excavations. In GSI (2003a), we prepared an addendum to GSI (2003b) providing the results of general corrosivity testing performed on a representative sample of the onsite soils. The test results showed thatthetestsamplewas mildly alkaline with respect to soil acidity/alkalinity; was moderately corrosive when moist; and did not contain detectable concentrations of soluble sulfates and chlorides. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 5 Both GSI (2003a and 2003b) are provided on the compact disc in Appendix A of this update report. RECENT SUPPLEMENTAL FIELD STUDIES On December 12, and 13, 2018, GSI conducted supplemental field work at the subject site. The field work included surficial mapping; logging nine (9) exploratory hollow-stem auger borings, advanced with a truck-mounted drill rig; and performing percolation tests in four (4) of the borings. The supplemental borings were advanced to primarily obtain information regarding the thickness and the engineering suitability of the existing fills, placed under the purview of (BEi, 1969), and to estimate infiltration rates of soils within the influence of the proposed infiltration trenches shown on MLB (2018). The logs of the previous explorations (modified as appropriate), and recent borings are presented in Appendix B. Plate 1 shows the approximate locations of the previous explorations and recent supplemental borings. PHYSIOGRAPHIC AND REGIONAL GEOLOGIC SETTINGS Physiographic Setting The site is located in the coastal plain physiographic section of San Diego County. The coastal plain section is characterized by pronounced marine wave-cut terraces intermittently dissected by stream channels that convey water from the eastern highlands to the Pacific Ocean. Regional Geologic Setting San Diego County lies within the Peninsular Ranges Geomorphic Province of southern California. This province is characterized as elongated mountain ranges and valleys that trend northwesterly (Norris and Webb, 1990). This geomorphic province extends from the base of the east-west aligned Santa Monica-San Gabriel Mountains, and continues south into Baja California, Mexico. The mountain ranges within this province are underlain by basement rocks consisting of pre-Cretaceous metasedimentary rocks, Jurassic metavolcanic rocks, and Cretaceous plutonic (granitic) rocks. The San Diego County region was originally a broad area composed of pre-batholithic rocks that were subsequently subjected to tectonism and metamorphism. In the late Cretaceous Period, the southern California Batholith was emplaced causing the aforementioned metamorphism of pre-batholithic rocks. Many separate magmatic injections originating from this body occurred along zones of structural weakness. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 6 Following batholith emplacement, uplift occurred, resulting in the removal of the overlying rocks by erosion. Erosion continued until the area was that of low relief and highly weathered. The eroded materials were deposited along the sea margins. Sedimentation also occurred during the late Cretaceous Period. However, subsequent erosion has removed much of this evidence. In the early Tertiary Period, terrestrial sedimentation occurred on a low-relief land surface. In Eocene time, previously fluctuating sea levels stabilized and marine deposition occurred. In the late Eocene, regional uplift produced erosion and thick deposition of terrestrial sediments. In the middle Miocene, the submergence of the Los Angeles Basin resulted in the deposition of thick marine beds in the northwestern portion of San Diego County. During the Pliocene, marine sedimentation was more discontinuous and generally occurred within shallow marine embayments. The Pleistocene saw regressive and transgressive sea levels that fluctuated with prograding and recessive glaciation. The changes in sea level had a significant effect on coastal topography and resultant wave erosion and deposition formed many terraces along the coastal plain. In the mid-Pleistocene, regional faulting separated highland erosional surfaces into major blocks lying at varying elevations. A later rise in sea level during the late Pleistocene, caused the deposition of thick alluvial deposits within the coastal river channels. In recent geologic time, crystalline rocks have weathered to form soil residuum, highland areas have eroded, and deposition of river, lake, lagoonal, and beach sediments has occurred. Regional geologic mapping by Kennedy and Tan (2008) indicates that the site is underlain by undivided, Quaternary-age (late to middle Pleistocene) old alluvial flood-plain deposits. This occurrence of this geologic unit, within the subject property, is supported by the lithologic traits identified in our recent and previous subsurface explorations and the local geomorphic conditions. For the purpose of this geotechnical report, GSI will refer to this geologic unit as Quaternary-age stream terrace deposits. This difference in nomenclature does not fundamentally alter our conclusions and recommendations pertaining to the proposed development of the subject site. SITE GEOLOGIC UNITS General The earth material units that were observed and/or encountered at the subject site during our recent field work, and our previous subsurface studies, performed in preparation of GSI (2003b) consisted of the existing fill, placed under the purview of BEi (1969), Quaternary-age colluvium (topsoil), Quaternary-age alluvium, and weathered, and unweathered Quaternary-age stream terrace deposits. The stream terrace deposits were identified in GSI (2003b) as belonging to the Sweitzer Formation. A general description of each material type is presented as follows, from youngest to oldest. The general distribution of these materials across the site is presented on Plate 1. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 7 Existing Artificial Fill (Map Symbol -Af) Existing fill was encountered at the surface in Test Pits TP-1 through TP-3 (GSI, 2003b); hollow-stem auger Borings B-1, B-3, and B-4; and all of the infiltration test borings (18-1 through 18-4). As observed therein, the fill primarily consisted of greenish gray silt; light gray and light yellowish gray sandy silt; brown, gray, dark brownish gray, light gray, dark gray, reddish yellow, light yellowish gray, very dark gray, medium gray, bluish gray, dark brown, grayish brown and brownish gray sandy clay; dark brownish gray, brown, light yellowish gray, dark gray, dark brown, grayish brown, reddish yellow, gray, and medium gray clayey sand; brown, light brownish gray, reddish yellow, yellow, light yellowish gray, light gray and dark gray silty sand; and brown, very fine-to coarse-grained sand. Locally, the existing fill contained subrounded to angular pebbles and subrounded cobbles. The existing fill was generally dry to saturated and soft/loose to hard/dense. Where encountered in our subsurface explorations, the thickness of the existing fill ranged between approximately 1 foot to approximately 22 feet thick. The thickest section of the existing fill was detected in hollow-stem auger Boring 8-1. Quaternary Colluvium (Not Mapped) Quaternary-age colluvium (topsoil) was encountered directly beneath the existing fill in Test Pits TP-1 and TP-2, and at the surface in Test Pit TP-4 (GSI, 2003b) and Boring B-5. As observed therein, the colluvium was on the order of½ foot to 2 feet in thickness, and typically consisted of red brown and red clayey sand and light brown, brownish gray, and red brown sandy clay with localized scattered cobbles. The colluvium was generally moist and loose/soft to stiff. The colluvium is considered potentially compressible in its existing state. Therefore, it should not be relied upon for the support of the proposed settlement-sensitive improvements and new planned fills without mitigation. Quaternary Alluvium (Not Mapped) GSI encountered what appeared to be left-in-place or reprocessed Quaternary-age alluvium beneath the existing fill in hollow-stem auger Boring 8-1. As observed therein, this earth material consisted of dark gray sandy clay that was wet to possibly saturated, and soft. The alluvium contained trace organic matter and emitted an odor consistent with decomposing organics. Quaternary Stream Terrace Deposits (Map Symbol -Qst) Quaternary-age stream terrace deposits were observed underlying the surficial earth materials in our previous test pits (GSI, 2003b), our recent hollow-stem auger Borings B-1 and 8-3 through 8-5, and our recent infiltration test Borings 18-1, 18-3, and 18-4. These deposits were also encountered at the surface in our recent hollow-stem auger Boring B-2. As observed in infiltration test Boring 18-1, the upper approximately 4 feet of these deposits were weathered in-place, and generally consisted of grayish brown silty sand with BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 8 abundant subangular pebbles that was dry and medium dense. Unweathered stream terrace deposits typically consisted of light reddish yellow, reddish yellow, yellowish brown, brown, brownish gray, light brownish gray, and gray sandy clayey gravel; yellowish brown, brown, reddish yellow, and gray gravelly sandy clay; brown and yellow clayey sandy gravel; light reddish brown, reddish brown, light grayish brown, light brownish gray, grayish brown, and light brown silty sand with localized traces of clay, subangular and angular pebbles, and scant to abundant rounded cobbles; brown, brownish gray, dark brown, light yellowish gray, light grayish brown, light brownish gray and grayish brown clayey sand with localized traces to abundant subangular and angular pebbles and cobbles; brown, light grayish brown, light brownish gray, and reddish brown sandy clay with localized scant to abundant subangular and angular pebbles; reddish brown clay with scattered cobbles and sand; light reddish brown silt; and grayish brown and light reddish brown very fine-to coarse-grained sand with localized traces of silt and angular, and subangular pebbles. In general, the unweathered stream terrace deposits were dry to wet and loose/soft to very dense/hard. The unweathered stream terrace deposits are considered suitable bearing materials at the subject site. Structural Geology Based on our experience, GSI estimates that bedding within the Quaternary-age stream terrace deposits is either subhorizontal or gently inclined in a westerly direction. No adverse geologic structures that would preclude project feasibility were encountered during our field work or indicated on the regional geologic maps reviewed. GROUNDWATER GSI did not observe evidence of a regional groundwater table nor perched groundwater during our field investigation. However, the left-in-place and/or reprocessed alluvium encountered in hollow-stem auger Boring B-1, between approximate depths of 22 and 25% feet BEG, appeared wet to possibly saturated. This suggests that ephemeral perched water may occur near the bottom of the former natural drainage course that was in-filled during the original grading of the site in 1969. The regional groundwater table is anticipated to be near sea level or approximately 70 feet below the lowest existing site elevation. Thus, the regional groundwater table is not anticipated to significantly affect proposed development of the subject site. Provided that the recommendations contained in this report are properly incorporated into final design and construction, groundwater is not anticipated to significantly affect the proposed site development. Our findings reflect the groundwater conditions at the time of our previous (GSI, 2003b) and recent field work, and do not preclude future changes in local groundwater conditions from excessive irrigation, precipitation, or that were not obvious, at the time of our studies. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 9 Owing to the nature of the onsite earth materials, perched groundwater conditions may occur locally either during or following site development (as the result of heavy and/or prolonged periods of precipitation, increased up-gradient irrigation practices, or damaged wet utilities) along zones of contrasting permeabilities/densities (i.e., fill lifts, fill/stream terrace deposit contacts, etc.) or along geologic discontinuities. This potential should be anticipated and disclosed to all interested/affected parties. UPDATED GEOLOGIC/SEISMIC HAZARDS EVALUATION General As part of this geotechnical update, GSI re-evaluated potential geologic/seismic hazards that could affect the currently proposed development at the subject site. Mass Wasting/Landslide Susceptibility Mass wasting refers to the various processes by which earth materials are moved down slope in response to the force of gravity. Examples of these processes include slope creep, surficial failures, and deep-seated landslides. Creep is the slowest form of mass wasting and generally involves the outer 5 to 10 feet of a slope surface. During heavy rains, such as those in El Nino years, creep-affected materials may become saturated, resulting in a more rapid form of downslope movement (i.e., landslides and/or surficial failures). According to regional landslide susceptibility mapping by Tan and Giffen (1995), the site is located within landslide susceptibility Subarea 3-1, which is characterized as being "generally susceptible" to landsliding. Tan and Giffen (1995) report that slopes within landslide susceptibility Subarea 3-1 are at or near their stability limits due to a combination of weak materials and steep slopes, many of which possess slope angles exceeding 15 degrees from the horizontal. Tan and Giffen (1995) further state that although most slopes in landslide susceptibility Subarea do not currently contain landslide deposits, slope failures can occur when these slopes are adversely modified. Geomorphic expressions indicative of past mass wasting events (i.e., scarps and hummocky terrain) were not observed during our recent and previous field studies. Further, no adverse geologic structures or landslide deposits were encountered during our subsurface exploration nor during our review of regional geologic maps. Owing to the above, the relatively gentle topography at the subject site and near-vicinity, and generally high strength characteristics of the stream terrace deposits, GSI concludes that the susceptibility of the proposed development to be affected by a deep-seated mass wasting event is low. The onsite soils are, however, considered erosive. Therefore, any slopes comprised of these materials may be subject to rilling, gullying, sloughing, and BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 10 surficial slope failures depending on rainfall severity and surface drainage practices. Such risks can be minimized through properly designed and regularly and periodically maintained surface drainage. Faults and Surface Rupture Based on our review of regional geologic maps (Kennedy and Tan, 2008), there are no active faults transecting the subject site. Therefore, the susceptibility of the site to surface rupture is considered low. Updated Seismicity The subject site is situated in a region subject to periodic earthquakes along active faults. According to Blake (2000a), the Rose Canyon fault is the closest known active fault to the site (located at a distance of approximately 6.7 miles [10.8 kilometers]) and should have the greatest effect on the site in the form of strong ground shaking, should the design earthquake occur. Cao, et al. (2003) indicate the slip rate on the Rose Canyon fault is 1.5 (±0.5) millimeters per year (mm/yr), and the fault is capable of a maximum magnitude 7.2 earthquake. The location of the Rose Canyon fault and other major faults within 100 kilometers of the site are shown on the "California Fault Map" in Appendix C. The possibility of ground acceleration, or shaking at the site, may be considered as approximately similar to the southern California region as a whole. Deterministic Site Acceleration The acceleration-attenuation relation of Bozorgnia, Campbell, and Niazi (1999) has been incorporated into EQFAULT (Blake, 2000a). EQFAULT is a computer program developed by Thomas F. Blake (2000a), which performs deterministic seismic hazard analyses using digitized California faults as earthquake sources. The program estimates the closest distance between each fault and a given site. If a fault is found to be within a user-selected radius, the program estimates peak horizontal ground acceleration that may occur at the site from an upper-bound (formerly "maximum credible earthquake"), on that fault. Upper-bound refers to the maximum expected ground acceleration produced from a given fault. Site acceleration (g) was computed by one user-selected acceleration-attenuation relation that is contained in EQFAUL T. Based on the EQFAUL T program, a peak horizontal ground acceleration from an upper-bound event on the Rose Canyon fault may be on the order of 0.53 g. The computer printouts of pertinent portions of the EQFAUL T program are included within Appendix C. Historical Site Acceleration Historical site seismicity was evaluated with the acceleration-attenuation relation of Bozorgnia, Campbell, and Niazi (1999), and the computer program EQSEARCH BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 11 (Blake, 2000b, updated to August 15, 2018). This program performs a search of the historical earthquake records for magnitude 5.0 to 9.0 seismic events within a 100-kilometer radius, between the years 1800 through August 15, 2018. Based on the selected acceleration-attenuation relationship, a peak horizontal ground acceleration is estimated, which may have affected the site during the specific time frame. Based on the available data and the attenuation relationship used, the estimated maximum (peak) site acceleration during the period 1800 through August 15, 2018 was about 0.37 g. A historic earthquake epicenter map and a seismic recurrence curve are also estimated/generated from the historical data. Computer printouts of the EQSEARCH program are presented in Appendix C. Seismic Shaking Parameters Based on the site conditions, the following table summarizes the site-specific design criteria obtained from the 2016 CBC (CBSC, 2016), Chapter 16 Structural Design, Section 1613, Earthquake Loads. The computer program "U.S. Seismic Design Maps, provided by the United States Geological Survey (2014) was utilized for design. The short spectral response utilizes a period of 0.2 seconds. 2016 CBC SEISMIC DESIGN PARAMETERS PARAMETER Site Class Spectral Response -(0.2 sec), s. Spectral Response -(1 sec), S1 Site Coefficient, F. Site Coefficient, Fv Maximum Considered Earthquake Spectral Response Acceleration (0.2 sec), SMs Maximum Considered Earthquake Spectral Response Acceleration (1 sec), SM1 5% Damped Design Spectral Response Acceleration (0.2 sec), S05 5% Damped Design Spectral Response Acceleration (1 sec), S01 PGAM Seismic Design Category BNR Investment and Development, LLC APN 216-170-14 and -15 VALUE D 1.039 g 0.402 g 1.000 1.398 1.039 g 0.562 g 0.693 g 0.375 g 0.403 g D File:e:\wp12\7500\7535a.gue GeoSoils, Inc. 2016 CBC AND/OR REFERENCE Section 1613.3.2/ASCE 7-10 (Chapter 20) Figure 1613.3.1 (1) Figure 1613.3.1 (2) Table 1613.3.3(1) Table1613.3.3(2) Section 1613.3.3 (Eqn 16-37) Section 1613.3.3 (Eqn 16-38) Section 1613.3.4 (Eqn 16-39) Section 1613.3.4 (Eqn 16-40) ASCE 7-10 (Eqn 11 .8.1) Section 1613.3.5/ASCE 7-10 (Table 11 .6-1 or 11 .6-2) W.O. 7535-A-SC February 4, 2019 Page 12 GENERAL SEISMIC PARAMETERS PARAMETER VALUE Distance to Seismic Source (Rose Canyon fault) 6.7 mi (10.8 km)(1> Upper Bound Earthquake (Rose Canyon fault) Mw = 7.2'2> '1> -Blake (2000a) '2> -Cao, et al. (2003) Conformance to the criteria above for seismic design does not constitute any kind of guarantee or assurance that significant structural damage or ground failure will not occur in the event of a large earthquake. The primary goal of seismic design is to protect life, not to eliminate all damage, since such design may be economically prohibitive. Cumulative effects of seismic events are not addressed in the 2016 CBC (CBSC, 2016) and regular maintenance and repair following locally significant seismic events (i.e., Mw5.5) will likely be necessary, as is the case in all of southern California. Secondary Seismic Hazards Liquefaction/Lateral Spreading Liquefaction describes a phenomenon in which cyclic stresses, produced by earthquake-induced ground motion, create excess pore pressures in relatively cohesionless soils. These soils may thereby acquire a high degree of mobility, which can lead to vertical deformation, lateral movement, lurching, sliding, and as a result of seismic loading, volumetric strain and manifestation in surface settlement of loose sediments, sand boils and other damaging lateral deformations. This phenomenon occurs only below the water table, but after liquefaction has developed, it can propagate upward into overlying non-saturated soil as excess pore water dissipates. One of the primary factors controlling the potential for liquefaction is depth to groundwater. Typically, liquefaction has a relatively low potential at depths greater than 50 feet and is unlikely and/or will produce vertical strains well below 1 percent for depths below 60 feet when relative densities are 40 to 60 percent and effective overburden pressures are two or more atmospheres (i.e., 4,232 pounds per square foot [Seed, 20051). The condition of liquefaction has two principal effects. One is the consolidation of loose sediments with resultant settlement of the ground surface. The other effect is lateral sliding. Significant permanent lateral movement generally occurs only when there is significant differential loading, such as fill or natural ground slopes within susceptible materials. No such loading conditions exist at the site. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 13 Liquefaction susceptibility is related to numerous factors and the following five conditions should be concurrently present for liquefaction to occur: 1) sediments must be relatively young in age and not have developed a large amount of cementation; 2) sediments must generally consist of medium-to fine-grained, relatively cohesionless sands; 3) the sediments must have low relative density; 4) free groundwater must be present in the sediment; and 5) the site must experience a seismic event of a sufficient duration and magnitude, to induce straining of soil particles. Only about one to perhaps two of these five necessary conditions have the potential to be present at the site, concurrently, under the design earthquake event. Seismic Densification Seismic densification is a phenomenon that typically occurs in low relative density granular soils (i.e., United States Soil Classification System [USCS] soil types SP, SW, SM, and SC) that are above the groundwater table. These unsaturated granular soils are susceptible if left in the original density (unmitigated), and are generally dry of the optimum moisture content (as defined by the ASTM D 1557). During seismic-induced ground shaking, these natural or artificial soils deform under loading and volumetrically strain, potentially resulting in ground surface settlements. The herein provided earthwork recommendations would mitigate seismic densification onsite. However, some densification of the adjoining un-mitigated properties may influence improvements at the perimeter of the site. Special setbacks and/or foundations may be utilized if significant structures/improvements are located above a 1 :1 (h:v) plane projected up from offsite, unmitigated soils. In order to mitigate seismic densification occurring on adjoining properties, foundations for buildings and walls, near the perimeter of the site, should extend below a 1 :1 (h:v) plane projected up and into the project area from the bottom the remedial grading excavation at the property lines. Supporting perimeter site improvements by vibro piers would also provide mitigation of seismic densification. Our evaluation assumed that the current offsite conditions will not be significantly modified by future grading at the time of the design earthquake, which is a reasonably conservative assumption. Summary It is the opinion of GSI that the susceptibility of the site to experience damaging deformations from seismically-induced liquefaction and densification is relatively low owing to the dense, nature of the stream terrace deposits that underlie the site. In addition, the recommendations for remedial earthwork, ground improvement, and foundations would further reduce any significant liquefaction/densification potential. Some seismic densification of the adjoining un-mitigated site(s) may adversely influence planned improvements at the perimeter of the site. However, given the remedial earthwork and foundation recommendations provided herein, the potential for the site to be affected by significant seismic densification or liquefaction of adjoining offsite soils may be considered low. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 14 Other Geologic/Secondary Seismic Hazards The following list includes other geologic/seismic related hazards that have been considered during our evaluation of the site. The hazards listed are considered negligible and/or mitigated as a result of site location, soil characteristics, and typical site development procedures: • Subsidence • Ground Lurching or Shallow Ground Rupture • Tsunami • Seiche ROCK HARDNESS/EXCAVATION FEASIBILITY During the subsurface exploration, performed in preparation of this update, practical refusal was encountered when advancing a hollow-stem auger into the Quaternary-age stream terrace deposits in Borings B-1 through B-3 at depths ranging between approximately 7 feet and 265/12 feet BEG. Our observations of drill rig behavior while advancing the auger into the stream terrace deposits suggest that an abundance of gravel constituents produced non-productive drilling rather than lithification. Therefore, GSI anticipates that excavations into the onsite earth materials would with standard mechanized earth-moving equipment in good working order would vary from easy to moderately difficu It. Localized areas of cemented, Quaternary-age stream terrace deposits may present very difficult excavation. Excavation equipment should be appropriately sized and powered for the required excavation task. STORM WATER INFILTRATION RATE EVALUATION AND DISCUSSION Subsurface Exploration During GSl's recent site-specific field studies, four (4) infiltration test borings (18-1 through 18-4) were advanced with a hollow-stem auger drill rig to depths ranging between approximately 9 feet and 11 feet BEG. The purpose of the borings was to evaluate the site's near-surface soil and geologic conditions, and to conduct percolation testing to develop preliminary soil infiltration rates with respect to permanent stormwater best management practices (BMPs)/low impact development (LID). The test borings (18-1 through 18-4) were logged by a GSI representative. The logs of these borings are provided in Appendix B. Their approximate locations are presented on the Geotechnical Map (Plate 1). BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 15 United States Department of Agriculture (USDA)/Natural Resources Conservation Service (NRCS) Soil Survey A review of the United States Department of Agriculture/Natural Resources Conservation Service database ([USDA/NRCS]; 1973, 2018) indicates thatthe surficial soil units mapped at the site consist primarily of the Huerhuero loam, 5 to 9 percent slopes (eroded), and a very small area of localized Altamont clay, 9 to 15 percent slopes. The USDA/NRCS indicates the capacity of the most limiting layers of the Huerhuero loam and Altamont clay to transmit water are very low to moderately low (0.00 to 0.06 inches per hour [in/h]), and moderately low to moderately high (0.06 to 0.20 in/hr), respectively. The Hydrologic Soil Group (HSG) for the Huerhuero loam, 5 to 9 percent slopes and Altamont clay, 9 to 15 percent slopes are "D" and "C," respectively. HSG D soils (Huerhuero loam) are generally not compatible with infiltration facilities, and the HSG C soils (Altamont clay) are very limited in areal extent throughout the site (i.e., comprising only approximately 0.3 percent of the site's surface area and confined to the southwesterly corner of the subject property). Currently, the area of the site to receive proposed permanent stormwater BMPs/LIDs is mantled by fine-grained, existing fill that is also low permeability. Infiltration Screening Feasibility Percolation testing was performed in Infiltration Borings 18-1 through 18-4 in general accordance with Riverside County Flood Control and Water Conservation District ([RCFC&WCD], 2011) guidelines. As indicated previously, the logs of Infiltration Borings 18-1 through 18-4 are presented in Appendix B. Prior to testing, the soils within Infiltration Boring 18-1 through 18-4 were pre-soaked by filling them with more than 5 gallons of water. Since water was still observed in the test borings after a 4-hour waiting period, the borings were allowed to pre-soak overnight. At the onset of testing the following day, GSI evaluated if the soil conditions in the test borings met the "sandy soil criteria" outlined in RCFC&WCD (2011) by adding water to the test borings and allowing the water level to fall over two (2) 25-minute test intervals to see if greater than a 6-inch change in water column height occurred within each test period. This test indicated that the soil conditions in test Borings 18-1 through 18-4 met the "sandy soil criteria." Thus, in general accordance with RCFC&WCD (2011) protocol, percolation testing in these borings continued over a 1-hour period, with readings taken every 1 0 minutes. Since the soil conditions in infiltration test Boring 18-4 did not meet the "sandy soil criteria" percolation testing in this boring continued for an additional 6 hours, with readings taken every 30 minutes. At the beginning of each test interval, the boring was refilled with water and the water level was allowed to drop. Both initial and final readings were rounded to the nearest¼ inch. The field percolation test data sheets are provided in Appendix C. The change in water height recorded during the last test interval was then used to calculate the infiltration rate using the Porchet Method, per RCFC&WCD (2011) guidelines. The calculation sheets BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 16 showing the conversion of the field percolation test data to infiltration rates are also provided in Appendix D. The following table presents the change in water column height in each infiltration test boring during the last test interval: INFILTRATION BORING NO. CHANGE IN WATER HEIGHT DURING FINAL TESTING PERIOD (INCHES) IB-1 3.0 IB-2 2.25 IB-3 3.0 IB-4 1.25 The following table summarizes the calculated infiltration rate within each test boring using Porchet Method: FILTRATION ST BORING IB-1 IB-2 IB-3 IB-4 INFILTRATION RATE INCHES PER HOUR 0.469 0.255 0.409 0.057 Avera e Rate = 0.297 in/hr Our calculations show an observed average infiltration rate of 0.297 in/hr. In accordance with Worksheet Form 1-9 of City of Carlsbad (2016), a suitability assessment safety factor (SA) equal to 2.0 was applied to the average infiltration rate to produce an estimated reliable infiltration rate of 0.148 in/hr. This is below the feasibility threshold for "Full Infiltration" of 0.5 inches/hr per the City of Carlsbad (2016), and 0.52 inches/hr per the Environmental Protection Agency, and suggests that "partial infiltration" of stormwater appears potentially feasible in the general vicinity of the test borings. However, since much of the site is underlain by existing fill that is subject to hydrocompression, stormwater infiltration at the subject site is not recommended. In addition to inducing hydrocompression of the existing fill, stormwater infiltration has the potential to create perched water conditions (i.e., groundwater mounding), activate expansive soils, and/or cause existing backfill to settle. This may culminate in distress to the proposed site improvements and existing improvements on adjacent property. Thus, GSI recommends a "no infiltration" feasibility screening designation for stormwater infiltration at the site. An BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 17 additional discussion of infiltration feasibility is presented in Appendix D, which includes the completed City of Carlsbad Forms 1-8 and 1-9. However, "Partial Infiltration" appears feasible by the use of a deep(± 15 to 25 feet) dry well with impermeable sides that allows an infiltration surface at elevations coincident with the Quaternary stream terrace deposits, at depth. This condition should not cause appreciable hydrocompression/hydroconsolidation, nor groundwater mounding that would affect existing surface improvements. LABORATORY TESTING Laboratory tests were performed on relatively undisturbed and representative bulk samples collected during our previous (GSI, 2003b) and recent subsurface work. The laboratory test procedures and results are presented herein and in Appendix E. Classification Soils were visually classified with respect to the Unified Soil Classification System (U.S.C.S.) in general accordance with ASTM D 2487 and D 2488. The soil classifications of the onsite soils are provided on the GSI (2003b) test pit logs and the boring logs from our recent subsurface exploration in Appendix B. Moisture-Density Relations The field moisture contents and dry unit weights were determined in the laboratory for selected, relatively undisturbed samples collected during the GSI (2003b) and our recent subsurface exploration. The dry unit weight was determined in pounds per cubic foot (pcf), and the field moisture content was determined as a percentage of the dry weight. The results of these tests are shown on the GSI (2003b) test pit logs and the boring logs from our recent field work in Appendix B. Laboratory Standard The maximum dry density and optimum moisture content was determined for the major soil types encountered in the GSI (2003b) test pits and our recent borings. The laboratory standard used was ASTM D 1557. The moisture-density relationship obtained for this soil is shown below: BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 18 SOIL TYPE SAMPLE LOCATION MAXIMUM DRY OPTIMUM MOISTURE AND DEPTH (FT) DENSITY (PCF) CONTENT(%) Red Brown, Silty SAND TP-1 @ 5 115.5 11 .5 Dark Brown, Sandy CLAY TP-2@ 3 122.5 11 .0 Dark Brown, Sandy Clay B-3@ 5-10 125.3 10.4 Expansion Index Expansion testing and expansion potential classification were performed on representative bulk samples of site soils in accordance with ASTM D 4829. The results of the GSI (2003b) and recent expansion testing are presented in the following table. 11 --.TION AND DEPTH (FT) EXPANSION INDEX EXPANSION POTE"'-• 11 TP-1 @ 5 <5 Very Low TP-2@ 3 91 High Atterberg Limits Testing was performed on selected representative fine-grained soil samples from the GSI (2003b) test pits and the recent borings to evaluate the liquid limit, plastic limit and plasticity index in general accordance with ASTM D4318-64. The test results are presented in the following table and in Appendix E. I LOCATION AND DEPTH (FT) I LIQUID LIMIT I PLASTIC LIMIT I PLASTICITY INDEX I TP-2@ 3 53 20 33 B-1@1-4 49 13 36 B-3@ 10 37 12 25 B-4@ 5 44 14 30 Swell Pressure A swell pressure test was performed on a relatively undisturbed sample of the existing fill obtained from Boring B-1 at an approximate depth of 5 feet below the existing grade. The swell pressure test was performed in general accordance with ASTM D 4546 Method A. The test indicated that following inundation, the sample required a load equivalent to BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 19 approximately 2,028 pounds per square foot (psf) to resist swell pressure in response to water added. The results of the swell pressure test are included in Appendix E. Direct Shear Test Shear testing was performed on representative, "undisturbed" and "remolded samples of site soil collected from the GSI (2003b) test pits and the recent borings in general accordance with ASTM Test Method D-3080 in a Direct Shear Machine of the strain control type. The shear test results are presented as follows and are provided in Appendix E: PRIMARY RESIDUAL BORING AND DEPTH (FT) COHESION FRICTION ANGLE COHESION FRICTION ANGLE (PSF) (DEGREES) (PSF) (DEGREES) TP-1 @ 4 88 38 42 39 (undisturbed) TP-2@ 7 1,618 26 1,576 27 (undisturbed) B-3@ 5-10 148 25.8 90 26.5 (remolded) Consolidation Testing Consolidation testing was performed on three (3) relatively undisturbed samples of the existing fill collected from the recent borings. Consolidation testing was performed in general accordance with ASTM Test Method D-2435-90. The consolidation test results are presented in Appendix E. The results of the consolidation tests indicated that the samples exhibited between approximately 4.6 and 7.4 percent hydrocompression when subjected to an 8,000 psf load . Corrosion/Sulfate Testing A representative sample of the site earth materials from the GSI (2003b) test pits was analyzed for a general assessment of soil corrosivity and soluble sulfates, and chlorides. The testing included evaluation of soil pH, soluble sulfates, chlorides, and saturated resistivity. Test results are presented in the following table and in Appendix: BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 20 SAMPLE LOCATION SATURATED SOLUBLE SOLUBLE AND DEPTH (FT) pH RESISTIVITY SULFATES CHLORIDES (ohm-cm) (% by weight) (ppm) TP-1 @ 5 7.5 9,600 ND ND ................ etectable concentration in tested sample. Corrosion Summary The previous laboratory testing indicates that the tested sample of the onsite soils is mildly alkaline with respect to soil acidity/alkalinity; is moderately corrosive to exposed, buried metals when saturated; and has non-detectable concentrations of soluble sulfates ("Exposure Class SO" per Table 19.3.1.1 of ACI 318-14), and soluble chlorides. GSI does not consult in the field of corrosion engineering. Thus, consultation from a qualified corrosion consultant may be considered based on the level of corrosion protection required for the project, as determined by the Project Architect, Structural Engineer, Civil Engineer, and Plumbing/Mechanical Engineers. On a preliminary basis, reinforced concrete mix design should conform to Exposure Classes "SO," "WO," and "C2," per Table 19.3.2.1 of ACI 318-14. PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS Based on our previous (GSI, 2003b) and recent field exploration, previous (GSI, 2003a; 2003b) and recent laboratory testing, and geotechnical engineering analysis, it is our opinion that the site appears suitable for the proposed development from a geotechnical engineering and geologic viewpoint, provided that the recommendations presented in the following sections are incorporated into the design and construction phases of site development. The primary geotechnical concerns with respect to the proposed development are: • Depth to competent bearing soils/suitability of existing artificial fill to support the proposed improvements • Potential for settlement of existing fills and associated distress, both onsite and offsite • Stormwater infiltration and associated adverse affects on the proposed development and adjacent properties • Expansion and corrosion potential of the onsite soils • Potential for perched groundwater after development • Temporary slope construction. • Regional seismic activity. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 21 The recommendations presented herein consider these as well as other aspects of the site. The engineering analyses performed concerning site preparation and the recommendations presented herein have been completed using the information provided and obtained during our previous field work. In the event that any significant changes are made to proposed site development, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and the recommendations of this report verified or modified in writing by this office. Foundation design parameters are considered preliminary until the foundation design, layout, and structural loads are provided to this office for review. 1. Soil engineering, observation, and testing services should be provided during grading to aid the contractor in removing unsuitable soils and in his effort to compact the fill. 2. Geologic observations should be performed during grading to verify and/or further evaluate geologic conditions. Although unlikely, if adverse geologic structures are encountered, supplemental recommendations and earthwork may be warranted. 3. Based on our review and recent, and previous (GSI, 2003b) site work, approximately two-thirds of the subject property is mantled by existing artificial fill placed in 1969, under the purview of BEi (1969). The fill materials where predominately placed within a northerly to northwesterly trending natural drainage channel in order to bring the site to current grades. Elsewhere, Quaternary-age stream terrace deposits occur in the near-surface and are discontinuously mantled by Quaternary-age colluvium (topsoil). Quaternary-age alluvium was encountered underlying the existing fill in Boring B-1, which was recently advanced near the axis of the former drainage channel in the vicinity of the northerly property boundary. 4. Laboratory tests indicate that the existing fill materials are non-uniform relative to density and degree of saturation, and were placed almost 50 years ago likely under a different compaction standard. Consolidation tests show the existing fill materials exhibit between 4.6 and 7.4 percent hydrocompression when subjected to an 8,000 psf load. Further, as observed in Boring 8-1, advanced near the center of the northerly property boundary, the fill appears to have been placed on left-in-place or partially reprocessed alluvial materials that are saturated and soft. Lastly, based on our review of BEi (1969), there is no documentation of the placement of a subdrain in the bottom of the in-filled drainage channel. Although infilled, this natural drainage channel remains a preferential pathway for groundwater. Thus, the lower section of the existing fill could be subjected to periodic wetting from perched groundwater, and undergo hydrocompression in response. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 22 5. In order to mitigate settlement of the existing fill materials under the proposed service loads, GSI recommends either limited remedial grading of the near-surface fills and the use of vibro piers (aggregate piers) to control settlement within proposed building areas, underground utility corridors, and retaining walls. Building Units "A," "C," and "E" will be candidate structures for the placement of vibro piers for support due to the existing cuVfill (exiting fill/stream terrace deposits) transition and the depth of the ±50-year old fill. Alternatively, the existing fill and any underlying alluvium should be entirely removed to expose suitable stream terrace deposits. Where planned cut areas will expose suitable, unweathered stream terrace deposits at finish grade, and where the existing fill, and surficial colluvial deposits have combined depths of 5 feet or less, a remedial grading approach may be employed. This grading solution will likely provide suitable support for Building Units "B" and "D." The excavated earth materials may be reused as compacted fill. New compacted fill materials should placed under the observation and testing of GSI. The alternative to perform the complete removal and recompaction of the existing fill and any underlying alluvial deposits would likely require shoring or slot grading along portions of the property boundaries. In addition, GSI recommends that a subdrain be installed along the axis of the natural drainage channel following remedial excavation and prior to fill placement if the complete removal and recompaction (of existing fills and alluvial materials) alternative is performed. Because there is not practical way of outletting the subdrain via gravity, a permanent sump pump would be necessary to convey the collected subsurface water into the onsite storm drain system if allowed by the City Engineer/Building Department. The maximum to minimum fill thickness beneath the proposed buildings, associated with the "full-depth" remedial grading alternative, should not exceed a ratio of 3:1 (maximum:minimum). This may require overexcavation of the stream terrace deposits and replacement fills. 6. For uniform support of proposed Buildings "A," "C," and "E," GSI recommends that either limited remedial grading be performed with building loads transferred into suitable stream terrace deposits via vi bro piers, or the existing fill materials and any underlying potentially compressible natural soils (i.e., alluvium, colluvium, and/or weathered stream terrace deposits) be removed and recompacted. In order to provide uniform support of proposed Buildings "B" and "D," and to help mitigate the shrink/swell effects of expansive soils and reduce the potential for post- development perched water conditions within the influence of these buildings, GSI recommends that these structures be underlain by a compacted fill blanket minimally extending to depths of 4 feet below pad grade or 24 inches below the lowest foundation element (whichever is greater). Once building foundation loads and load patterns become available, GSI can provide the areal layout of vi bro piers on the foundation plans. Additional subsurface exploration using cone penetration test (CPT) soundings may be needed to value engineer vibro pier locations/depth of treatment. Based on the available subsurface data vibro piers may extend to depths up to approximately 28½ feet BEG. Whereas, remedial earthwork excavations associated with the complete removal and recompaction of potentially BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 23 compressible, onsite earth materials would extend to depths up to approximately 251/3 feet BEG. 7. Laboratory tests performed in preparation of GSI (2003b) and this update indicate that the near-surface earth materials are very low to high in expansion potential with expansion indices ranging between 1 and 91 . Atterberg Limits tests performed in preparation of GSI (2003b) and this update indicate that the onsite soils have plasticity indices ranging between 25 and 36. Swell pressure testing, performed on a relatively undisturbed sample of the existing fill material, collected during our recent field exploration, indicates that a confining pressure equivalent to approximately 2,050 pounds per square feet (psf) is necessary to resist swell (uplift) pressure imparted by the tested sample. Thus, some of the onsite soils meet the criteria for expansive soils, as defined in Section 1803.5.3. of the 2016 CBC (CBSC, 2016). In order to comply with 2016 CBC requirements for the mitigation of expansive soils, the proposed residential structures will require specific foundation and slab-on-grade design that will tolerate the shrink/swell effects of expansive soils (see Sections 1808.6.1 and 1808.6.2 of the 2016 CBC). Alternatively, expansive soils within the influence of the proposed residential structures and/or associated improvements may be removed and replaced with very low expansive soils (E.I. of 20 or less) with a P.I. of 14 or less (see Section 1808.6.3 of the 2016 CBC). The implementation of earthwork as alternative mitigation for expansive soils will require a significant amount of selective grading (i.e., mining) and/or export, and import. Thus, earthwork mitigation of expansive soils should be evaluated on a cost versus benefit basis. Expansive soils are predominately associated with the existing fill materials, colluvium, and alluvium. The Quaternary-age stream terrace deposits are predominately granular in nature, but do contain zones of fine-grained soils, which could exhibit expansive characteristics. 8. Laboratory tests, performed in preparation of GSI (2003a) indicate that a tested sample of the onsite soils is mildly alkaline with respect to soil acidity/alkalinity; is moderately corrosive to exposed, buried metals when saturated; and has non-detectable concentrations of soluble sulfates ("Exposure Class SO" per Table 19.3.1.1 of American Concrete Institute [ACI] 318-14) and soluble chlorides. GSI does not consult in the field of corrosion engineering. Thus, consultation from a qualified corrosion consultant may be considered based on the level of corrosion protection required for the project, as determined by the Project Architect, Structural Engineer, Civil Engineer, and Plumbing/Mechanical Engineers. Additional testing relative to the general corrosivity of soils exposed near finish grade are recommended at the conclusion of grading. 9. GSI did not encounter a regional groundwater table nor perched water within our previous (GSI, 2003b) and recent subsurface explorations. However, the left-in-place and/or reprocessed alluvium encountered in hollow-stem auger Boring B-1, between approximate depths of 22 and 251/3 feet BEG, appeared wet to possibly saturated (Appendix B). This suggests that ephemeral perched water BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 24 may occur near the bottom of the former natural drainage course that was in-filled during the original grading of the site in 1969. The regional groundwater table is anticipated to be near sea level or approximately 70 feet below the lowest existing site elevation. Thus, the regional groundwater table is not anticipated to significantly affect proposed development of the subject site. Perched groundwater may occur along the geologic contact between the existing fill materials and the underlying Quaternary-age stream terrace deposits, owing to the permeability/density contrasts between these earth materials. Similarly, perched groundwater could occur along fill lifts and geologic discontinuities. Sources of perched water may include but not necessarily be limited to up-gradient irrigation practices, seasonal rainfall, and/or damaged wet underground utilities. Our findings reflect the groundwater conditions at the time of the GSI (2003b) and our recent field work, and do not preclude future changes in local groundwater conditions that were not obvious, at the time of our studies. The potential for perched groundwater to be encountered both during and following site development should be disclosed to all interested/affected parties. 10. On a preliminary basis, temporary slopes should be constructed in accordance with Cal-OSHA guidelines for Type "B" soil conditions provided that groundwater and running sands are not present. All temporary slopes should be observed by the geotechnical consultant during construction. If adverse conditions are exposed in temporary slopes, the slopes would need to be inclined to flatter gradients or shoring would need to be installed. Should property boundaries or existing improvements that are to remain in service limit the recommended temporary slope construction, the installation of shoring and/or slot grading would be recommended. Recommendations for the design and construction of shoring and alternating slot excavations are included in this report. 11 . Our field testing and analysis relative to the infiltration rates of on site earth materials in proximity to the proposed permanent stormwater BMPs/LIDs, shown on MLB (2018), indicates that an estimated reliable infiltration rate of 0.148 in/hr may be considered in the design of infiltration BMPs/LIDs. This rate falls within the "partial infiltration" designation for stormwater BMPs. However, it is our opinion that if stormwater infiltration were to occur onsite, the infiltrated water would perch upon the less permeable stream terrace deposits or fine-grained fill materials, and then migrate laterally, leading to saturation of fills and backfills, located both on site and offsite. In response, the weakened fills and backfill could settle. In addition, wetting of expansive soils could induce heave. Both phenomena would likely contribute to improvement distress both onsite and offsite. Therefore, stormwater treatment through infiltration is not recommended at the subject site. Rather stormwater treatment should occur in contained systems (i.e., precast concrete vaults) or utilize deep infiltration, as discussed previously. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 25 12. The seismicity-acceleration values provided in this report should be considered during the design of the proposed development. 13. General Earthwork and Grading Guidelines are provided at the end of this report as Appendix F. Specific recommendations are provided below. EARTHWORK CONSTRUCTION RECOMMENDATIONS General All earthwork should conform to the guidelines presented in the 2016 CBC (CBSC, 2016), the requirements of the City of Carlsbad, and the General Earthwork and Grading Guidelines presented in Appendix F, except where specifically superceded in the text of this report. Prior to earthwork, a GSI representative should be present at the preconstruction meeting to provide additional earthwork guidelines, if needed, and review the earthwork schedule. This office should be notified in advance of any fill placement, supplemental regrading of the site, or backfilling underground utility trenches and retaining walls after rough earthwork has been completed. This includes grading for drive lanes, approaches, and exterior hardscape. During earthwork construction, all site preparation and the general grading procedures of the contractor should be observed and the fill selectively tested by a representative(s) of GSI. If unusual or unexpected conditions are exposed in the field, they should be reviewed by this office and, if warranted, modified and/or additional recommendations will be offered. All applicable requirements of local and national construction and general industry safety orders, the Occupational Safety and Health Act (OSHA), and the Construction Safety Act should be met. It is the onsite general contractor's and individual subcontractors' responsibility to provide a safe working environment for our field staff who are onsite. GSI does not consult in the area of safety engineering. Site Preparation All existing vegetation and deleterious debris should be removed from the site prior to the start of construction if they are located in areas of proposed earthwork. Any remaining cavities should be observed by the geotechnical consultant who can provide recommendations for mitigation. The mitigation of cavities would largely be based on the extent of the cavity. Limited Remedial Excavation -Buildings "A," "C," and "E" and Adiacent Drive Aisles and Landscape Areas If vibro piers will be used to support proposed Buildings "A," "C," and "E," GSI recommends limited remedial excavations for partial support of the proposed slab-on- grade floors areas. The limited remedial excavations should include the upper 4 feet of BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 26 existing fill materials below pad grade elevation, and extend at least 5 feet outside the proposed building footprints. In proposed drive aisles and landscape areas, the near-surface existing fills should be excavated to at least 3 feet below subgrade elevation of the drive lane and at least 2 feet below the bottom of site retaining wall footings, as applicable. The limited remedial excavations in drive lane and landscape areas should be completed below a 1 :1 (h:v) plane projected down from the subgrade elevation at the edge of pavement and below the bottom outboard edges of retaining wall footings If suitable unweathered Quaternary-age stream terrace deposits are encountered above these recommended excavation depths, the remedial excavation may be halted. However, overexcavation of the stream terrace deposits in planned building areas should be performed per the recommendations in the "Overexcavation" section of this report, as warranted. The excavated soil may be reused as structural fill, provided that it is cleaned of any organic matter and deleterious debris, prior to or during placement. GSI should observe and perform field density testing and selective tactile probing on existing fill materials exposed at the bottom of remedial excavations. Should tactile probing and field density testing indicate that the existing fill is yielding or exhibits in-place densities less than 90 percent of the laboratory standard (per ASTM D 1557), deeper remedial excavation would be recommended. Once observed and approved for suitability, the bottom of the remedial excavation should be scarified at least 6 to 8 inches, moisture conditioned to at least the soil's optimum moisture content, and then recompacted to a minimum 90 percent of the laboratory standard (ASTM D 1557). Overexcavation -Buildings "B" and "D" and Portions of Buildings "A," "C," and "E" Exposing Suitable Unweathered Stream Terrace Deposits at Pad Grade In order to provide uniform support of building foundations and slab-on-grade floors, any Quaternary stream terrace deposits located within 4 feet of pad grade or 2 feet below the lowest building foundation element (whichever is greater) should be overexcavated and replaced with compacted fill. Overexcavation should be completed to at least 5 feet outside the perimeter foundations of the building. The maximum to minimum fill thickness beneath the proposed buildings, associated with the "full-depth" remedial grading alternative, should not exceed a ratio of 3:1 (maximum:minimum). This may require overexcavation of stream terrace deposits and replacement fills. The bottom of the overexcavation should be sloped toward drive lanes, Viejo Castilla Way, or the thickest section offill within building pad areas. Once completed the bottom of the overexcavation should be observed by GSI and then scarified at least 6 to 8 inches, moisture conditioned to at least the soil's optimum moisture content, and then recompacted to a minimum 90 percent of the laboratory standard (ASTM D 1557). BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 27 Alternating Slot Excavations Alternating (A, B, and C) slot excavations should be performed when conducting remedial earthwork adjacent to property lines and existing improvements that need to remain in serviceable use so as to not cause damage to offsite property or improvements. Slot excavations should be a maximum of 6 feet in width. Multiple slots may be simultaneously excavated provided that open slots are separated by at least 12 feet of approved engineered fill or undisturbed soils. Alternating slot excavations should not extend more than 9 feet deep without the assistance of shoring. Perimeter Conditions It should be noted that the 2016 CBC (CBSC, 2016) indicates that removals of unsuitable soils be performed across all areas to be graded, under the purview of the grading permit, not just within the influence of the proposed residential structures. Relatively deep removals may also necessitate a special zone of consideration, on perimeter/confining areas. This zone would be approximately equal to the depth of removals, if removals cannot be performed onsite or offsite. In general, any planned improvement located above a 1 :1 (h:v) projection up from the bottom, outboard edge of the remedial grading excavation at the property boundary would be affected by perimeter conditions and potentially offsite improvements. Proposed improvements, such as perimeter retaining walls, would require deepened foundations or additional reinforcement by means of ground improvement or specific structural design for mitigation of the perimeter conditions, discussed above. Otherwise, these improvements may be subject to distress and a reduced serviceable life span. This will also require proper disclosure to any owners and all interested/affected parties should this condition exist at the conclusion of grading. Fill Placement Reused onsite soils and import (if necessary) should be placed in ±6-to ±8-inch lifts, cleaned of vegetation and debris, moisture conditioned to at least 2 to 3 percentage points above the soil's optimum moisture content, and be compacted to achieve a minimum relative compaction of 90 percent of the laboratory standard (per ASTM D 1557). Field density testing should be performed by the geotechnical consultant during fill placement. Benching should be provided on all surfaces steeper than 5:1 (h:v) prior to fill placement. Earthwork Mitigation of Expansive Soils As an alternative to the use of specific structural design for the mitigation of expansive soils, the expansive onsite soils may be removed and replaced with very low expansive import or onsite earth materials such that the the weighted plasticity index of the onsite earth materials in the upper 15 feet of finish grade does not exceed 15. It should be noted that this type of mitigation may require a fairly substantial amount of import and export. Alternatively, soil-cement may be used to mitigate expansive soils. The feasibility of this type of mitigation should be considered only after a value engineering review is performed. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 28 If requested, GSI can provide additional recommendations for earthwork mitigation of expansive soils. Import Soils If import fill is necessary, a sample of the soil import should be evaluated by this office prior to importing, in order to assure compatibility with the onsite soils and the recommendations presented in this report. If non-manufactured materials are used, environmental documentation for the export site should be provided for GSI review. At least five business days of lead time should be allowed by builders or contractors for proposed import submittals. This lead time will allow for environmental document review, particle size analysis, laboratory standard, expansion testing, and blended import/native characteristics as deemed necessary. Import soils not intended for the mitigation of expansive soils should have an E.I. of 50 or less and a P.I. of 14 or less. Placement of expansive soils within proposed drive aisles may increase the thickness of the pavement structural section. The use of subdrains at the bottom of the fill cap may be necessary, and may be subsequently recommended based on compatibility with onsite soils. Graded Slope Construction General MLB (2018) indicates the construction of an approximately 3-foot high cut slope near the southeasterly corner of the subject site. Provided that the recommendations in this report are incorporated into the construction of the cut slope and project landscaping, GSI anticipates that this slope will be grossly and surficially stable. Our opinion regarding graded slope stability assumes proper slope construction, normal rainfall, adequate vegetative covering, positive drainage away from the top of slope, and periodic maintenance over the life of the project. Cut Slopes The cut slope should be constructed at gradients no steeper than 2:1 (h:v) and should be observed by the geotechnical consultant during construction. Should adverse conditions be exposed within the cut slope, it should be overexcavated and replaced with a compacted 2:1 (h:v) fill slope. Other Geotechnical Considerations • The slope should receive a deep-rooted, drought tolerant vegetative covering immediately following construction. In the interim between construction and the establishment of landscape cover, the slope should receive City-approved erosion control devices. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 29 • The project landscape plan should consider the use of drip-system irrigation with moisture sensors on the slope. • Surface drainage should be directed away from the top of the graded slope. Conveyance of surface runoff along the toe of the slope should be avoided or transported in lined swales or through piping. Storage or infiltration of surface runoff along the toe of the slope should be avoided, if possible. • The condition of the slope should be periodically reviewed and any deficiencies should be corrected as soon as possible. If requested, this office can provide additional consultation regarding the maintenance of the slope. Temporary Slopes Temporary slopes for excavations greater than 4 feet, but less than 20 feet in overall height should conform to CAL-OSHA and/or OSHA requirements for Type "B" soils, provided water or seepage and/or running sands are not present. Temporary slopes, up to a maximum height of ±20 feet, may be excavated at a 1: 1 (h:v) gradient, or flatter, provided groundwater and/or running sands are not exposed. Construction materials or soil stockpiles should not be placed within 'H' of any temporary slope where 'H' equals the height of the temporary slope. All temporary slopes should be observed by a licensed engineering geologist and/or geotechnical engineer prior to worker entry into the excavation. Based on the exposed field conditions, inclining temporary slopes to flatter gradients or the use of shoring may be necessary if adverse conditions are observed. If adverse conditions are exposed or if temporary slopes conflict with property boundaries, or existing improvements that need to remain in serviceable use, shoring or alternating slot excavations may be necessary. The need for shoring or alternating slot excavations could be further evaluated during the grading plan review stage and during site earthwork. Surcharges on temporary slopes from soil stockpiles, heavy equipment, traffic, and existing structures will require evaluation. Excavation Observation and Monitoring (All Excavations) -All Alternatives When excavations are made adjacent to an existing improvement (i.e., utility, wall, road, building, etc.) there is a risk of some damage even if a well designed system of excavation is planned and executed. We recommend, therefore, that a systematic program of observations be made before, during, and after construction to determine the effects (if any) of construction on existing improvements. We believe that this is necessary for two reasons: First, if excessive movements (i.e., more than ½ inch) are detected early enough, remedial measures can be taken which could possibly prevent serious damage to existing improvements. Second, the responsibility for damage to the existing improvement can be determined more equitably if the cause and extent of the damage can be determined more precisely. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 30 Monitoring should include the measurement of any horizontal and vertical movements of the existing structures/improvements. Locations and type of the monitoring devices should be selected prior to the start of construction. The program of monitoring should be agreed upon between the project team, the site surveyor and the Geotechnical Engineer-of-Record, prior to excavation. Reference points on existing walls, buildings, and other settlement-sensitive improvements. These points should be placed as low as possible on the wall and building adjacent to the excavation. Exact locations may be dictated by critical points, such as bearing walls or columns for buildings; and surface points on roadways or curbs near the top of the excavation. For a survey monitoring system, an accuracy of a least 0.01 foot should be required. Reference points should be installed and read initially prior to excavation. The readings should continue until all construction below ground has been completed and the permanent backfill has been brought to final grade. The frequency of readings will depend upon the results of previous readings and the rate of construction. Weekly readings could be assumed throughout the duration of construction with daily readings during rapid excavation near the bottom of the excavation. The reading should be plotted by the Surveyor and then reviewed by the Geotechnical Engineer. In addition to the monitoring system, it would be prudent for the Geotechnical Engineer and the Contractor to make a complete inspection of the existing structures both before and after construction. The inspection should be directed toward detecting any signs of damage, particularly those caused by settlement. Pre-construction notes should be made and photographs or video recordings should be taken where necessary. Observation It is recommended that all excavations be observed by the Geologist and/or Geotechnical Engineer. Any fill which is placed should be approved, tested, and verified if used for engineered purposes. Should the observation reveal any unforseen hazard, the Geologist or Geotechnical Engineer will recommend treatment. Please inform GSI at least 24 hours prior to any required site observation. Earthwork Balance (Shrinkage/Bulking) -All Alternatives The volume change of excavated materials upon compaction as engineered fill is anticipated to vary with material type and location. The overall earthwork shrinkage and bulking may be approximated by using the following parameters: Existing Undocumented Fill ......................... 5% shrinkage to 5% bulking Quaternary Colluvium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 to 8% shrinkage Quaternary Stream Terrace Deposits .......................... 2% to 3% bulking BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 31 It should be noted that the above factors are estimates only, based on preliminary data. The undocumented fill and colluvium may achieve higher shrinkage if organics or clay content is higher than anticipated, if a high degree of porosity is encountered, or if compaction averages more than 92 percent of the laboratory standard (ASTM D 1557). In addition, rodent burrowing may result in higher shrinkage. Final earthwork balance factors could vary. In this regard, it is recommended that balance areas be reserved where grades could be adjusted up or down near the completion of grading in order to accommodate any yardage imbalance for the project. GROUND IMPROVEMENT -VIBRO PIERS -BUILDING UNITS "A", "C," AND "E" In order to reduce estimated vertical deformations to proposed building foundations, slab-on-grade floors, walls, and underground utilities resulting from secondary compression and settlement of the left-in-place existing fill, ground improvement should be performed using "Rigid inclusions" or "vibro piers." This method improves bearing capacity and partially mitigates expansive soils (if present at the bearing elevation). This method also improves static and seismic performance with respect to the conventional remedial grading treatments, with a readily adjustable treatment depth. Differential settlement due to fill/stream terrace deposits contacts can also be addressed by this method. The ground improvement using this method may require an off-haul of excess (vibro pier spoil) materials. Vibro pier design should be provided by a speciality subcontractor, using the information provided herein. Vibro piers may be 18 to 24 inches in diameter and consist of ½ to 1 inch (in dimension) crushed rock vibrated into a pre-drilled hole using bottom-feed vibrators and the dry-feed method. Some expansion of the surrounding soil may occur during vibration and offsite vibration is possible along the perimeter of the site. GSI recommends that each bearing element and utilidor be supported with a series of vi bro piers minimally extending from the bottom of the footing (bearing elevation)/utilidor to the top of the suitable stream terrace deposits. Spacing of the vibro piers need not be less than 4 feet but no greater than 8 feet (center-to-center) within the footings and the area ratio of the vibro piers within the foundation elements should not be less than 18 percent. On a preliminary basis, vibro piers should extend at least 3 feet into suitable, unweathered stream terrace deposits. Based on the available subsurface data vibro piers may extend up to approximately 28½ feet BEG. However, longer vi bro piers may be necessary based on the actual depth of suitable stream terrace deposits at each vi bro pier location. For preliminary estimating purposes, Plate 1 provides the approximate depth of suitable stream terrace deposits BEG. If the stream terrace deposits are less than 5 feet below the bearing elevation, conventional remedial grading techniques may be used within the influence of the planned foundations and no vi bro piers are needed. Sequencing for vibro pier work will follow the near-surface remedial earthwork that establishes the rough grade of the site. Vi bro pier installation will precede the construction of foundation elements and utilidors. The number, layout and depths of this treatment may BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 32 be approximated in vertical and areal limits when the foundation plans are furnished to our office. Please note that when estimating vibro pier work, newly-placed remedial grading efforts associated with the proposed development will not be considered in the treatment depths or treatment zone. The vi bro pier work would extend through any newly placed fill and, although they will not treat this fill material, they would leave the top portion of the gravel column above the treated zone up to the pad grade, top of wall footing, and top of utilidor elevations. If desired, a 1-foot gravel cap can be included in the work so that the building footings are bearing upon this gravel material in lieu of bearing on existing or newly placed fill and alternately gravel columns. This should be a construction consideration and is not a geotechnical requirement. Following installation, at least two vi bro piers per building should be subjected to modulus testing. Details of this test will be provided once the foundation plans and specifications are prepared. Alternative ground improvement or foundation support alternatives may be considered in a value engineering study. ALTERNATIVE REMEDIAL GRADING In lieu of the combined limited remedial grading and vibro piers for support of the proposed buildings, underground utilities, and retaining walls, the existing fills and any underlying alluvial deposits may be removed in their entirety and then reused as compacted fill per the recommendations in the "Fill Placement" section of this report. If performed, remedial excavations extending to depths of up to 251/3 feet BEG are possible, based on the available subsurface data. However, localized deeper remedial excavations cannot be precluded and should be anticipated. For preliminary estimating purposes, Plate 1 provides the approximate depth of suitable stream terrace deposits BEG. The maximum to minimum fill thickness beneath the proposed buildings, associated with the "full-depth" remedial grading alternative, should not exceed a ratio of 3:1 (maximum:minimum). This may require overexcavation of stream terrace deposits and replacement fills. Given the high volume of excavated earth materials, site logistics may not allow for efficient stockpiling of such. In other words, there may not be sufficient area onsite to stockpile the excavated earth materials. This remedial grading alternative will require shoring and/or slot grading along some property boundaries to execute. In addition, a subdrain should be installed along the axis of the northerly to northwesterly trending natural drainage channel subsequent to the removal of the existing fill and any underlying alluvium, prior to fill placement. The subdrain should consist of a minimum 6-inch diameter schedule 40 or SOR 35 perforated drain pipe, encased in clean ¾-inch gravel that is entirely wrapped in filter fabric (Mirafi 140N or approved equivalent). The minimum volume of gravel used in subdrain construction should be 9 cubic feet of gravel per lineal foot of subdrain. Since there is no practical way of outletting the subdrain via gravity, it should be connected into a sump pump installed near the lowest invert elevation of the subdrain. The sump pump should be tightlined into the onsite stormwater system if allowed by the City Engineer and Building BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 33 Department. The sump pump should be an enclosed system in order to avoid saturation of the surrounding soils. The sump should also be a double-redundant system equipped with alarms. PRELIMINARY RECOMMENDATIONS -FOUNDATIONS General Preliminary recommendations for foundation design and construction are provided in the following sections. These preliminary recommendations have been developed from our understanding of the currently proposed site development and our previous (GSI; 2003a, 2003b) and recent site investigations. Foundation design should be re-evaluated at the conclusion of site grading/remedial earthwork for the as-graded soil conditions. Although not anticipated, revisions to these recommendations may be necessary. In the event that the information concerning the proposed development plan is not correct, or any changes in the design, location or loading conditions of the proposed residential structures are made, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or approved in writing by this office. The information and recommendations presented in this section are not meant to supercede design by the project structural engineer or civil engineer specializing in structural design. Upon request, GSI could provide additional input/consultation regarding soil parameters, as they relate to foundation design. The preliminary geotechnical data indicates the subject site is underlain by very low to highly expansive soils (E.I. of <5 to 130). However, a majority of near-surface soils consists of existing fill, which laboratory testing shows is high in expansion potential with plasticity indices ranging between 25 and 36. Furthermore, swell pressure testing on the existing fill shows it can exert uplift pressure on the order of 2,050 psf. In order to resist deformations attributed to the shrink/swell effects of expansive soils, building foundations and slab-on-grade floor systems should receive specific structural design for conformance with Sections 1808.6.1 and 1808.6.2 of the 2016 CBC. In other words, the proposed buildings should utilize either post-tensioned or mat foundation systems. However, given the relatively large footprints of the proposed buildings and the incorporation of retaining walls into some buildings, the use of post-tensioned foundation systems may not be practical. Thus, GSI has provided preliminary recommendations for the design and construction of post-tensioned and mat foundation systems in this report. In order to control settlement, proposed Buildings "A," "C," and "E," underlain by left-in-place, existing fill, should be supported by vibro piers extending through the fill into the underlying Quaternary stream terrace deposits per the recommendations previously provided in this report. Alternatively, full-depth remedial grading, conforming to the recommendations in this report, can be performed to control settlement within the influence of building foundations. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 34 Shallow Foundation Design Building "A" Through "E" 1. The foundation systems should be designed and constructed in accordance with guidelines presented in the 2016 CBC (CBSC, 2016) and the methodologies presented by the Post-Tensioning Institute ([PTI]; 2004, 2008, 2012, 2013, and 2014) or the Wire Reinforcement Institute ([WRI], 1996). 2. An allowable vertical bearing value of 2,000 pounds per square foot (psf) may be used for design of continuous footings 12 inches wide and 12 inches deep, and for the design of isolated pad footings 24 inches square and 24 inches deep, bearing upon at least 2 feet of compacted fill placed and compacted under the supervision of the geotechnical consultant. All isolated pad footings should be connected by grade beam or tie beam in at least two directions. The bearing value may be increased by 20 percent for each additional 12 inches in footing depth to a maximum value of 2,500 psf. The above values may be increased by one-third when considering short duration seismic or wind loads. No increase in bearing for footing width is recommended. For shallow foundations supported by vibro piers, as recommended herein, an allowable vertical bearing value of 2,500 psf may be used in the design. 3. For lateral sliding resistance, a 0.30 coefficient of friction may be utilized for a concrete to soil contact when multiplied by the dead load. 4. The passive earth pressure may be computed as an equivalent fluid having a density of 150 pcf with a maximum earth pressure of 1,500 psf. Passive pressure should be neglected in the upper 6 inches of the footing if it is not confined by concrete slabs or pavement. 5. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. 6. All footing setbacks from slopes should comply with Figure 1808.7.1 of the 2016 CBC. GSI recommends a minimum horizontal setback distance of 7 feet as measured from the bottom, outboard edge of the footing to the slope face. Based on our understanding of the currently proposed development, setbacks from slopes are not anticipated. 7. Footings for structures adjacent to retaining walls should be deepened so as to extend below a 1 :1 (h:v) plane projected up from the heel of the wall footing. Post-Tension Foundation Systems Building Units "A" Through "E" Post-tension foundations may be used to mitigate the damaging shrink/swell effects of the onsite expansive soil conditions on the proposed building foundations and slab-on-grade floors. However, the use of post-tension foundation systems may be limited due to the size BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 35 of the proposed building footprints and/or the incorporation of retaining walls for some building walls. The post-tension foundation designer may elect to exceed the minimal recommendations, provided herein, to increase slab stiffness performance. Post-tension (PT) design may be either ribbed or mat-type. The latter is also referred to as uniform thickness foundation (UTF). The use of a UTF is an alternative to the traditional ribbed-type. The UTF offers a reduction in grade beams. That is to say a UTF typically uses a single perimeter grade beam and "shovel" footings, but has a thicker slab than the ribbed-type. UTF perimeter footings may utilize an allowable vertical bearing value of 2,500 psf if supported by vibro piers, as described herein. The information and recommendations presented in this section are not meant to supercede design by a registered structural engineer or civil engineer qualified to perform post-tensioned design. Post-tension foundations should be designed using sound engineering practice and be in accordance with local and 2016 CBC requirements. Upon request, GSI can provide additional data/consultation regarding soil parameters as related to post-tension foundation design. From a soil expansion/shrinkage standpoint, a common contributing factor to distress of structures using post-tensioned slabs is a "dishing" or "arching" of the slabs. This is caused by the fluctuation of moisture content in the soils below the perimeter of the slab primarily due to onsite and offsite irrigation practices, climatic and seasonal changes, and the presence of expansive soils. When the soil environment surrounding the exterior of the slab has a higher moisture content than the area beneath the slab, moisture tends to migrate inward, underneath the slab edges to a distance beyond the slab edges referred to as the moisture variation distance. When this migration of water occurs, the volume of the soils beneath the slab edges expands and causes the slab edges to lift in response. This is referred to as an edge-lift condition. Conversely, when the outside soil environment is drier, the moisture transmission regime is reversed and the soils underneath the slab edges lose their moisture and shrink. This process leads to dropping of the slab at the edges, which leads to what is commonly referred to as the center lift condition. A well-designed, post-tensioned slab having sufficient stiffness and rigidity provides a resistance to excessive bending that results from non-uniform swelling and shrinking slab subgrade soils, particularly within the moisture variation distance, near the slab edges. Other mitigation techniques typically used in conjunction with post-tensioned slabs consist of a combination of specific soil pre-saturation and the construction of a perimeter "cut-off" wall grade beam. Soil pre-saturation consists of moisture conditioning the slab subgrade soils prior to the post-tension slab construction. This effectively reduces soil moisture migration from the area located outside the building toward the soils underlying the post-tension slab. Perimeter cut-off walls are thickened edges of the concrete slab that impedes both outward and inward soil moisture migration. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 36 Slab Subgrade Pre-Soaking Pre-moistening of the slab subgrade soil is recommended to reduce the potential for post- construction soil heave. The moisture content of the subgrade soils should be equal to or greater than optimum moisture to a depth equivalent to the perimeter grade beam or cut-off wall depth in the slab areas (typically 12, 18, or 24 inches for low, medium, or highly expansive soil conditions, respectively). Pre-moistening and/or pre-soaking should be evaluated by the soils engineer 72 hours prior to vapor retarder placement. In summary: EXPANSION PAD SOIL MOISTURE CONSTRUCTION SOIL MOISTURE POTENTIAL METHOD RETENTION Upper 12 inches of pad soil Periodically wet or cover Low Wetting and/or with plastic after trenching. moisture 2 percent over (E.I. = 21-50) optimum (or 1.2 times) reprocessing Evaluation 72 hours prior to placement of concrete. Upper 18 inches of pad soil Periodically wet or cover Medium Berm and flood or wetting with plastic after trenching. moisture 2 percent over (E.I. = 51-90) optimum (or 1.2 times) and reprocessing Evaluation 72 hours prior to placement of concrete. Upper 24 inches of pad soil Periodically wet or cover High moisture 3 percent over Berm and flood or wetting with plastic after trenching. (E.I. = 91 -130) optimum (or 1.3 times) and reprocessing Evaluation 72 hours prior to olacement of concrete. Perimeter Cut-Off Walls Perimeter cut-off walls should be at least 12, 18, or 24 inches deep for low, medium, or highly expansive soil conditions, respectively. The cut-off walls may be integrated into the slab design or independent of the slab. The cut-off walls should be a minimum of6 inches thick (wide). The bottom of the perimeter cut-off wall should be designed to resist tension, using cable or reinforcement per the structural engineer. Post-Tension Foundation Design The following recommendations for design of post-tensioned slabs have been prepared in general compliance with the requirements of the recent Post Tensioning lnstitute's (PTl's) publication titled "Design of Post-Tensioned Slabs on Ground, Third Edition" (PTI, 2004), together with it's subsequent addendums and errata (PTI; 2008, 2012, 2013, and 2014). BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 37 Post-Tension Foundation Soil Support Parameters The recommendations for soil support parameters have been provided based on the typical soil index properties for soils that are very low to very high in expansion potential. The soil index properties are typically the upper bound values based on our experience and practice in the southern California area. Additional testing is recommended either during or following grading, and prior to foundation construction to further evaluate the soil conditions within the upper 7 to 15 feet of pad grade. The following table presents suggested minimum coefficients to be used in the Post-Tensioning Institute design method. Thornthwaite Moisture Index -20 inches/year Correction Factor for Irrigation 20 inches/year Depth to Constant Soil Suction 7 feet or overexcavation depth to bedrock Constant soil Suction (pf) 3.6 Moisture Velocity 0. 7 inches/month Effective Plasticitv Index (P.U* 20-40** * -The effective plasticity index should be evaluated for the upper 7 to 15 feet of foundation soils either during or following grading. ** -Onsite Pl values obtained from lab testina ranaed between 25 and 36 Based on the above, the recommended post-tension soil support parameters are tabulated below: DESIGN PARAMETERS LOW EXPANSION MEDIUM EXPANSION HIGH EXPANSION CE.I. = 21-50) CE.I. = 51-90) CE.I. = 91-130) em center lift 9.0 feet 8.7 feet 8.5 feet em edge lift 5.2 feet 4.5 feet 3.75 feet Ym center lift 0.4 inches 0.66 inches 0.75 inches Ym edge lift 0.7 inch 1.3 inch 1.7 inches Bearing Value (1> 1,000 psf 1,000 psf 1,000 psf Lateral Pressure 150 psf 150 psf 150 psf Subgrade Modulus (k) 1 00 pci/inch 85 pci/inch 70 pci/inch Minimum Perimeter 12inches 18inches 24inches Footing Embedment (2> 1'1 Internal bearing values within the perimeter of the post-tension slab may be increased to 2,000 psf for a minimum embedment of 12 inches, then by 20 percent for each additional foot of embedment to a maximum of 2,500 psf. Footings bearing directly on vibro piers may utilize a vertical bearing of 2,500 psf. 121 As measured below the lowest adjacent compacted subgrade surface without landscape layer or sand underlayment. Note: The use of ooen bottomed raised olanters adiacent to foundations will reauire more onerous desian oarameters. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 38 The parameters are considered minimums and may not be adequate to represent all expansive soils and site conditions such as adverse drainage and/or improper landscaping and maintenance. The above parameters are applicable provided the structure has positive drainage that is maintained away from the structure. In addition, no trees with significant root systems are to be planted within 15 feet of the perimeter of foundations. Therefore, it is important that information regarding drainage, site maintenance, trees, settlements, and effects of expansive soils be passed on to future all interested/affected parties. The values tabulated above may not be appropriate to account for possible differential settlement of the slab due to other factors, such as excessive settlements. If a stiffer slab is desired, alternative Post-Tensioning Institute ([PTI] third edition) parameters may be recommended. All exterior columns not supported by the post-tensioned foundation should be supported by 24 square inch isolated footings extending at least 24 inches into approved engineered fill. Exterior column footings should be tied to the post-tensioned foundation with 12 square inch, reinforced grade beams in at least two directions. Mat Foundations In lieu of using a post-tension foundation to tolerate expansive soil effects, the Client may consider a mat foundation which uses steel bar reinforcement instead of post-tensioned cables. The structural engineer may supercede the following recommendations based on the planned building loads and use. WRI (Wire Reinforcement Institute) methodologies for design may be used. Mat foundations may be incorporate exterior and interior stiffening beams or a uniform thickness slab (UTF). Minimum mat embedment should be 12 inches below the lowest adjacent grade if a uniform thickness slab is utilized. Mat Foundation Design The design of mat foundations should incorporate the vertical modulus of subgrade reaction. This value is a unit value for a 1-foot square footing and should be reduced in accordance with the following equation when used with the design of larger foundations. This is assumes that the bearing soils will consist of at least 2 feet of newly compacted fills with an average relative compaction of 90 percent of the laboratory (ASTM D 1557). Mat foundations overlying vi bro piers may utilize an allowable bearing value of 2,500 psf. K. = K [B 1]2 R S 28 . where: K8 = unit subgrade modulus ~ = reduced subgrade modulus B = foundation width (in feet) BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 39 The modulus of subgrade reaction (K8) and effective plasticity index (P.I.) to be used in mat foundation design for various expansive soil conditions are presented in the following table. LOW EXPANSION MEDIUM EXPANSION HIGH EXPa.N:SILIN II (E.I. = 21-50) (E.I. = 51-90) (E.I. = 91-1 Ks = 100 pci/inch Pl <25 Ks =85 pci/inch, Pl= 25 Ks = 70 pci/inch Pl= 35 The effective plasticity index for the upper 7 to 15 feet of the foundation soils should be performed during or following grading. Lateral pressures and sliding coefficients for mat foundation design should conform to those previously provided in the "Shallow Foundation Design" section of this report. Slab Subgrade Pre-Soaking Slab subgrade pre-soaking should conform to the recommendations previously provided in the post-tensioned foundation section of this report. Perimeter Cut-Off Walls Perimeter cut-off walls should be at least 12, 18, or 24 inches deep for low, medium, or highly expansive soil conditions, respectively. The cut-off walls may be integrated into the slab design or independent of the slab. The cut-off walls should be a minimum of 6 inches thick (wide). The bottom of the perimeter cut-off wall should be designed to resist tension, using steel reinforcement per the structural engineer FOUNDATION AND FILL SETTLEMENT GSI has evaluated the onsite soils for density, moisture content, compression characteristics (consolidation), and plasticity (Atterberg Limits). The fill on the site was placed approximately 50 years ago in a former drainage channel that transected the site, prior to original grading. GSI has evaluated this fill and the underlying formational earth materials (Quaternary stream terrace deposits) by subsurface exploration using borings and test pits (GSI, 2003b [Appendix A]). These evaluations have produced the following findings: • The existing fill soils are expansive and have moderate to high plasticity (Pl =25 to 36). BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 40 • The existing fills may have been placed under a different fill compaction standard. Although documentation suggested the ASTM 1557 was used, this was not common for this locale at the time of the original earthwork. • Fill soils have increased in moisture content since original placement, and are generally above optimum moisture content with percent saturation ranging between 63 and 99 percent. In other words, the existing fill is typically above the optimum moisture content that was documented at the time of original fill placement; and, therefore is considered wet of optimum in a number of the boring and test pit samples evaluated onsite. This may be due to the lack of drainage/subdrainage within the fill. • The stream terrace deposits are dense and not considered significantly compressible, but do exhibit expansive properties, locally. • It is unknown if the existing fill was placed on properly benched or "keyed" surfaces excavated into the stream terrace deposits during original grading. The local presence of alluvium and colluvium between the fill and the stream terrace deposits suggests that the original grading in one or more areas of the site does not conform with the current standard of care for fill placement. Based on the above findings and settlement analysis of the data collected, GSI has concluded that the fill, in its present condition, may present a differential settlement potential for Buildings "A," "C," and "E" of more than 2¼ inches over the length of the structures (i.e., greater than 1 ½ inches in 40 feet). Based on this conclusion, GSI does not recommend installing or constructing these buildings without significant remedial earthwork or ground improvement, as discussed herein. Due to the localized expansive nature of the stream terrace deposits and the potential for post-development perched groundwater to manifest, it is not recommended to construct or install Buildings "B" and "D" on existing stream terrace deposits. Rather, Buildings "B" and "D" will require overexcavation and/or remedial grading. Following this recommended earthwork and/or ground improvement, differential settlement of 1 inch in 40 lateral feet is anticipated. Dynamic or seismic settlement is not anticipated to significantly contribute to these estimates if the remedial earthwork and ground improvement recommended herein is performed. Some permanent deformation (lateral and vertical) of the existing bedrock and fill is possible following the design level ground shaking. SOIL MOISTURE TRANSMISSION CONSIDERATIONS GSI has evaluated the potential for vapor or water transmission through new concrete floor slabs, in light of typical floor coverings and improvements. Please note that slab moisture emission rates range from about 2 to 27 lbs/24 hours/1,000 square feet from a typical slab BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 41 (Kanare, 2005), while floor covering manufacturers generally recommend about 3 lbs/24 hours as an upper limit. The recommendations in this section are not intended to preclude the transmission of water or vapor through the foundation or slabs. Foundation systems and slabs shall not allow water or water vapor to enter into the structure so as to cause damage to another building component or to limit the installation of the type of flooring materials typically used for the particular application (State of California, 2019). These recommendations may be exceeded or supplemented by a water "proofing" specialist, project architect, or structural consultant. Thus, the client will need to evaluate the following in light of a cost vs. benefit analysis (owner expectations and repairs/replacement), along with disclosure to all interested/affected parties. It should also be noted that vapor transmission will occur in new slab-on-grade floors as a result of chemical reactions taking place within the curing concrete. Vapor transmission through concrete floor slabs as a result of concrete curing has the potential to adversely affect sensitive floor coverings depending on the thickness of the concrete floor slab and the duration of time between the placement of concrete, and the floor covering. It is possible that a slab moisture sealant may be needed prior to the placement of sensitive floor coverings if a thick slab-on-grade floor is used and the time frame between concrete and floor covering placement is relatively short. Considering the E.I. test results presented herein, and known soil conditions in the region, the anticipated typical water vapor transmission rates, floor coverings, and improvements (to be chosen by the Client and/or project architect) that can tolerate vapor transmission rates without significant distress, the following alternatives are provided: • Concrete slab-on-grade floors, including garage slabs, should be thicker than 5 inches. The project structural engineer may require a thicker slab-on-grade to mitigate expansive soil conditions or accommodate proposed loading and use. • Concrete slab underlayment should consist of a 15-mil vapor retarder, or equivalent, with all laps sealed per the 2016 CBC and the manufacturer's recommendation. The vapor retarder should comply with the ASTM E 1745 -Class A criteria (i.e., Stego Wrap or approved equivalent), and be installed in accordance with ACI 302.1 R-04 and ASTM E 1643. • The 15-mil vapor retarder (ASTM E 1745 -Class A) shall be installed per the recommendations of the manufacturer, including all penetrations (i.e., pipe, ducting, rebar, etc.). • Concrete slabs, including the garage slab, should be underlain by 2 inches of clean, washed sand (SE > 30) above a 15-mil vapor retarder (ASTM E-17 45 -Class A, per Engineering Bulletin 119 [Kanare, 2005]) installed per the recommendations of the manufacturer, including all penetrations (i.e., pipe, ducting, rebar, etc.). The manufacturer shall provide instructions for lap sealing, including minimum width of lap, method of sealing, and either supply or specify suitable products for lap sealing (ASTM E 1745), and per code. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 42 ACI 302.1 R-04 (2004) states "If a cushion or sand layer is desired between the vapor retarder and the slab, care must be taken to protect the sand layer from taking on additional water from a source such as rain, curing, cutting, or cleaning. Wet cushion or sand layer has been directly linked in the past to significant lengthening of time required for a slab to reach an acceptable level of dryness for floor covering applications." Therefore, additional observation and/or testing will be necessary for the cushion or sand layer for moisture content, and relatively uniform thicknesses, prior to the placement of concrete. • For expansive soil conditions (i.e., E.I. > 20 and P.I. > 14 [typically low to very high expansion potential]), the vapor retarder shall be underlain by a capillary break consisting of at least 4 inches of clean crushed gravel with a maximum dimension of¾ inch (less than 5 percent passing the No. 200 sieve). • On a preliminary basis, the maximum water to cement ratio of concrete used in foundation and slab-on-grade construction should not exceed 0.50. A more onerous concrete water to cement ratio may be required after the completion of soil corrosion testing. Additional concrete mix design recommendations should be provided by the structural consultant and/or waterproofing specialist. Concrete finishing and workablity should be addressed by the structural consultant and a waterproofing specialist. • Where slab water/cement ratios are as indicated herein, and/or admixtures used, the structural consultant should also make changes to the concrete in the grade beams and footings in kind, so that the concrete used in the foundation and slabs are designed and/or treated for more uniform moisture protection. • The developer and/or tenant should be specifically advised which areas are suitable for tile flooring, vinyl flooring, or other types of water/vapor-sensitive flooring and which areas are not suitable for these types of flooring applications. In all planned floor areas, flooring shall be installed per the manufactures recommendations. • Additional recommendations regarding water or vapor transmission should be provided by the architect/structural engineer/slab or foundation designer and should be consistent with the specified floor coverings indicated by the architect. Regardless of the mitigation, some limited moisture/moisture vapor transmission through the slab cannot be entirely precluded and should be anticipated. Construction crews may require special training for installation of certain product(s), as well as concrete finishing techniques. The use of specialized product(s) should be approved by the slab designer and water-proofing consultant. A technical representative of the flooring contractor should review the slab and moisture retarder plans and provide comment prior to the construction of the foundation or improvement. The vapor retarder contractor should have representatives onsite during the initial installation. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 43 RETAINING WALL DESIGN PARAMETERS General It is our understanding that the project includes the construction of retaining walls to accommodate grade transitions associated with the proposed buildings and site design/layout. Recommendations for the design and construction of conventional masonry and cast-in-place retaining walls are included herein. Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site-specific conditions. The following recommendations assume that the proposed retaining walls will be supported through remedial grading and/or vi bro piers. Conventional Retaining Walls The design parameters provided below assume that either very low expansive soils (typically Class 2 permeable filter material or Class 3 aggregate base) or native onsite materials with an expansion index of 20 or less and a plasticity index of 20 or less are used to backfill any retaining wall. The type of backfill (i.e., select or native), should be specified by the wall designer, and clearly shown on the wall plans. Based on the available subsurface data, it is unlikely that the onsite earth materials are suitable for use as retaining wall backfill. This should be considered in the design and construction of the proposed retaining walls. The use of waterproofing is recommended for all retaining walls in order to reduce the potential for efflorescence staining at the face. Preliminary Retaining Wall Foundation Design -Shallow Foundations, Grading And Vibro Pier Mitigated Soil Preliminary foundation design for retaining walls supported by shallow foundations should incorporate the following recommendations. Vibro piers should be used to support retaining foundations underlain by left-in-place existing fills. Minimum Footing Embedment -24 inches below the lowest adjacent grade into either recompacted fills observed and tested by this firm or suitable unweathered stream terrace deposits. Minimum Footing Width -24 inches Allowable Bearing Pressure -An allowable bearing pressure of 2,000 psf may be used in the preliminary design of shallow retaining wall foundations provided that the footing maintains a minimum width of 24 inches and minimally extends at least 24 inches into new structural fills (recompacted onsite earth materials) directly overlying suitable unweathered stream terrace deposits. An allowable bearing pressure of 2,500 psf may be used in the preliminary design of shallow retaining wall foundations provided that the footing maintains a minimum width of 24 inches and minimally extends at least 24 inches into suitable, unweathered stream terrace BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 44 deposits or fill materials improved by the installation vibro piers, per the recommendations in this report. This pressure may be increased by one-third for short-term wind and/or seismic loads. Passive Earth Pressure -A passive earth pressure of 150 pcf with a maximum earth pressure of 1,500 psf may be used in the preliminary design of retaining wall foundations provided the foundation is embedded in earth materials considered suitable for lateral support by the geotechnical consultant. Where retaining wall footings are located adjacent to landscape areas (i.e., not confined by concrete slabs or pavement, the passive resistance should be neglected in the upper 6 inches of the foundation design). Lateral Sliding Resistance -A 0.30 coefficient of friction may be utilized for a concrete to soil contact when multiplied by the dead load. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. Backfill Soil Density -Soil densities ranging between 11 0 pcf and 115 pcf may be used in the design of retaining wall foundations. This assumes an average engineered fill compaction of at least 90 percent of the laboratory standard (ASTM D 1557). Additional Design Considerations • Where tiered retaining walls are proposed, the wall designer should evaluate if the upper proposed retaining wall foundation is located above a 1 :1 (h :v) plane projected up from the heel of the lower proposed retaining wall footing. Should this be the case, the foundation for the proposed upper retaining wall should extend below a 1 :1 (h:v) plane projected up from the heel of the lower retaining wall. Restrained Walls Any retaining wall that will be restrained prior to placing and compacting backfill material or that have re-entrant or male corners, should be designed for an at-rest equivalent fluid pressure (EFP) of 55 pcf and 65 pcf for select backfill and very low expansive native backfill with a plasticity index of 14 or less, respectively. The design should include any applicable surcharge loading. For areas of male or re-entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall (2H) laterally from the corner. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 12 feet high. Design parameters for walls less than 3 feet in height may be superceded by County of San Diego regional standard design. It should be noted that regional standard design BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 45 requires the use of select backfill materials (i.e.,clean sand or gravel backfill). Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. These do not include other superimposed loading conditions due to traffic, structures, seismic events or adverse geologic conditions. When wall configurations are finalized, the appropriate loading conditions for superimposed loads can be provided upon request. For preliminary planning purposes, the structural consultant/wall designer should incorporate the surcharge of traffic on the back of retaining walls where vehicular traffic could occur within horizontal distance "H" from the back of the retaining wall (where "H" equals the wall height). The traffic surcharge may be taken as 100 psf/ft in the upper 5 feet of backfill for light truck and car traffic. This does not include the surcharge of parked vehicles which should be evaluated at a higher surcharge to account for the effects of seismic loading. Equivalent fluid pressures for the design of cantilevered retaining walls are provided in the following table: SURFACE SLOPE OF EQUIVALENT EQUIVALENT RETAINED MATERIAL FLUID WEIGHT P.C.F. FLUID WEIGHT P.C.F. (HORIZONTAL:VERTICAL) (SELECT BACKFILL)121 (NATIVE BACKFILL)<3> LeveI<1> 38 50 2 :1 55 65 <1> Level backfill behind a retaining wall is defined as compacted earth materials, properly drained, without a slope for a distance of 2H behind the wall, where H is the height of the wall. <2> SE 2::,. 30, P.I. < 15, E.I. < 21, and .:s_ 10% passing No. 200 sieve. <3> E.I. = Oto 50, SE > 30, P.I. < 15, E.I. < 21 , and < 15% passing No. 200 sieve. Seismic Surcharge For retaining walls incorporated into the residential structures, site retaining walls with more than 6 feet of retained materials as measured vertically from the bottom of the wall footing at the heel to daylight, or retaining walls that could present ingress/egress constraints in the event offailure, GSI recommends that the walls be evaluated for seismic surcharge in general accordance with 2016 CBC requirements. The retaining walls in this category should maintain an overturning Factor-of-Safety (FOS) of approximately 1.25 when the seismic surcharge (increment), is applied. For restrained walls, the seismic surcharge should be applied as a uniform surcharge load from the bottom of the footing (excluding shear keys) to the top of the backfill at the heel of the wall footing. This seismic surcharge pressure (seismic increment) may be taken as 15H where 11H11 for restrained walls is the dimension previously noted as the height of the backfill to the bottom of the footing. For cantilevered walls, a seismic increment of 15H should be applied as an inverted triangular pressure distribution from 0.6H from the bottom of the footing to the top BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 46 of the wall. For the evaluation of the seismic surcharge, the bearing pressure may exceed the static value by one-third, considering the transient nature of this surcharge. Please note this is for local wall stability only. The 15H is derived from a Mononobe-Okabe solution for both restrained cantilever walls. This accounts for the increased lateral pressure due to shakedown or movement of the sand fill soil in the zone of influence from the wall or roughly a 45° -<l>/2 plane away from the back of the wall. The 15H seismic surcharge is derived from the formula: Ph=%• ah• Y1H Where: Ph = ah = Yt = H = Seismic increment Probabilistic horizontal site acceleration with a percentage of "g" Total unit weight (110 to 115 pcf for site soils @ 90% relative compaction). Height of the wall from the bottom of the footing or point of pile fixity. Retaining Wall Backfill and Drainage Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabric and outlets. Otherwise, retaining walls should be designed for full hydrostatic pressure. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Details 1, 2, and 3, present the backdrainage options discussed below. Backdrains should consist of a 4-inch diameter perforated PVC or ABS pipe encased in either Class 2 permeable filter material or ¾-inch to 1 ½-inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent). The backdrain should flow via gravity (minimum 1 percent fall) toward an approved drainage facility. For select backfill, the filter material should extend a minimum of 1 horizontal foot behind the base of the walls and upward at least 1 foot. For native backfill that has up to E.I. = 20, continuous Class 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, and it should be constructed in accordance with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited access and confined areas, (panel) drainage behind the wall may be constructed in accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an expansion index (E.I.) potential of greater than 20 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should conform with Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). Retaining wall backfill should be moisture conditioned to 1.1 to 1.2 times the soil's optimum moisture content, placed in relatively thin lifts, and compacted to at least 90 percent of the laboratory standard (ASTM D 1557). Weeping/drainage of wall backfill near property lines is not recommended. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 47 (1) Waterproofing membrane -- CMU or reinforced-concrete wall ±12 inches Proposed grade t - sloped to drain per precise civil drawings (5) Weep hole ~\jJ-\ \~0--!-)\ \--<\Y---___ , \ \-----.:::::\_;.---\ \ \:;:,~\ \ (<; Footing and wall design by others,-----""'-~ Structural footing or settlement-sensitive improvement Provide surface drainage via an engineered V-ditch (see civil plans for details) 2=1 (h=v) slope . . ... · ... · : . . :: ._.· .. :·< .i > ~, .:·--.·.··:Sl?pE(.or·.-~~·~if < .. :.· .~ .<.·.: / ·_: .. ·.;· _.. --·-· ·-· :.·.~ -· ·-. _ .. ~·: ..... . .. . ... • .. ··. ·. . . :. . .. .. ...·.· .. · .. . -.· •• •• •• •• ••• ·: ••• • i •••• ·.:. • :·:· y : : <·••·•.·····•· : :. ···•·· i' .·· ···.· · .. ·(2)"Gravel .: · · · .. · · ,.,_. · ,,. . ·. :· .. ~ .·.·· .'·. :· · .. :·.<· :· ~· ·:·:. ::· ·;-.·: ..... · {':< ... · ..... · (3) .Filter• :fa · · .-· · , _ ....... ~ ,, . •,. . . .. ·. : .:_ ~ · .. :•: : . . ... . :· . . Native backfill 1=1 (h=v) or flatter backcut to be properly benched (6) Footing (1) Waterproofing membrane. (2) Gravel= Clean, crushed, ¾ to 1½ inch. (3) Filter fabric= Mirafi 140N or approved equivalent. (4) Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient sloped to suitable, approved outlet point (perforations down). (5) Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surface. Design civil engineer to provide drainage at toe of wall. No weep holes for below-grade walls. (6) Footing: If bench is created behind the footing greater than the footing width, use level fill or cut natural earth materials. An additional "heel" drain will likely be required by geotechnical consultant. c. RETAINING WALL DETAIL -ALTERNATIVE A Detail 1 4 . (1) Waterproofing membrane (optional)-~ CMU or reinforced-concrete wall l 6inchea 1- (5) Weep hole Proposed grade sloped to drain per precise civil drawings /<)~:\\'§(\~~~\~'\ Footing and wall design by others----""--~ Structural footing or settlement-sensitive improvement Provide surface drainage via engineered V-ditch (see civil plan details) 2=1 (h=v) slope Native backfill 1=1 (h=v) or flatter backcut to be properly benched ---(6) 1 cubic foot of ¾-inch crushed rock (7) Footing (1) Waterproofing membrane (optional): Liquid boot or approved mastic equivalent. (2) Drain= Miradrain 6000 or J-drain 200 or equivalent for non-waterproofed walls; Miradrain 6200 or J-drain 200 or equivalent for waterproofed walls (all perforations down). (3) Filter fabric: Mirafi 140N or approved equivalent; place fabric flap behind core. (4) Pipe= 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient to proper outlet point (perforations down). (5) Weep hole= Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surface. Design civil engineer to provide drainage at toe of wall. No weep holes for below-grade walls. (6) Gravel= Clean, crushed,¾ to 1½ inch. (7) Footing= If bench is created behind the footing greater than the footing width, use level fill or cut natural earth materials. An additional "heel" drain will likely be required by geotechnical consultant. c. RETAINING WALL DETAIL -ALTERNATIVE B Detail 2 (1) Waterproofing membrane-~ CMU or reinforced-concrete wall ±12 inches 7- (5) Weep hole H [ Proposed grade sloped to drain per precise civil drawing~ <~\S;-\\);(\\~\~ Footing and wall design by others Structural footing or settlement-sensitive improvement r---Provide surface drainage 2=1 (h=v) slope ·:· . . ........ · .. . :: :·· ·. :·:_-, .i. ·: :· .:: .:·--.:--:s1~~e.:.~r-.'f~.v~.r:.: : ... :.· .-. ::· ....... , .... :: ·.··:· .' ,___ ..... -.·.·· ... · .. i.• . ..;..........;; ·._ .. : ·_-_._·. · .. -'. .· .. . . ·. . ·. / .. . ... . . ·-: .. -:>*:: ... :. : .. ···_ .•. ··.·.•···•>··•.·.•··•··•#' .. . . ·. ···.. .. : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ·: ... ::.,,·~:'\Y ::::::::.·:::.·:::.·:::.·: . . . ·. ·-< :· ' ..... ··.·:.. \ \ .·.·.·.·.·•·.·.·•·.·.·•·.·.·.· .. ·.·.·.·: ·1 .: ·· . .' •, ..................... :-:<-:-:-:-:-:-:-:.:-:-:-:-:-:-:-:-:-:-:-:-:-·-· ... · .. · ~ . · .... · ... ......................... . . . . . . . . . . . . . . . . . . . . . . . . . ·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.· ; .. ·.·· .·:· ·. ...................... . . . . . . . . . . . . . . . . . . . . . . . . . · . . . . . . . . . . . . . . . . . . . . . . . . ::. ............ .......... . . . . . . . . . ...... ./ \ (3) Filter fabric (2) Gravel (4) Pipe (8) Native backfill (6) Clean sand backfill 1=1 (h=v) or flatter backcut to be properly benched (7) Footing (1) Waterproofing membrane= Liquid boot or approved masticequivalent. (2) Gravel= Clean, crushed, ¾ to 1½ inch. (3) Filter fabric= Mirafi 140N or approved equivalent. (4) Pipe= 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient to proper outlet point (perforations down). (5) Weep hole= Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surface. Design civil engineer to provide drainage at toe of wall. No weep holes for below-grade walls. (6) Clean sand backfill= Must have sand equivalent value (S.E.) of 35 or greater; can be densified by water jetting upon approval by geotechnical engineer. (7) Footing= If bench is created behind the footing greater than the footing width, use level fill or cut natural earth materials. An additional "heel" drain will likely be required by geotechnical consultant. (8) Native backfill= If El. (21 and S.E. ~35 then all sand requirements also may not be required and will be reviewed by the geotechnical consultant. c. RETAINING WALL DETAIL -ALTERNATIVE C Detail 3 . . ii Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no greater than ± 100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes, only, in walls higher than 2 feet, is not recommended. The surface of the backfill should be sealed by pavement or the top 18 inches compacted with native soil (E.I. ~ 50). Proper surface drainage should also be provided. For additional mitigation, consideration should be given to applying a water-proof membrane to the back of all retaining structures. The use of a waterstop should be considered for all concrete and masonry joints. Wall/Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from cut to fill, the civil designer may specify either: a) A minimum of a 2-foot overexcavation and recompaction of cut materials for a distance of 2H, from the point of transition. b) Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints or crack control joints) such that a angular distortion of 1 /360 for a distance of 2H on either side of the transition may be accommodated. Expansion joints should be placed no greater than 20 feet on-center, in accordance with the structural engineer's/wall designer's recommendations, regardless of whether or not transition conditions exist. Expansion joints should be sealed with a flexible, non-shrink grout. c) Embed the footings entirely into native formational material (i.e., deepened footings). If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation "a" (above) and until such transition is between 45 and 90 degrees to the wall alignment. SHORING DESIGN AND CONSTRUCTION Shoring of Excavations Should the Client elect to remove and recompact the existing fill, colluvium, and alluvium in lieu of ground improvement, shoring would be necessary along portions of the property boundaries. In addition, shoring may be necessary if there is insufficient space to construct temporary backcuts for proposed retaining walls, per the recommendations in the "Temporary Slopes" section of this report. A temporary cantilever shoring system typically derives passive support from cast-in-place soldier piles. The use of tiebacks or soil nails appears unfeasible due to the site's location adjacent to existing developed properties. Therefore, the use of internal braces, rakers, BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 51 and/or temporary slopes may be used to achieve the maximum shoring height needed to perform remedial grading and retaining wall installation. Shoring of excavations of this size is typically performed by specialty contractors with knowledge of the City of Carlsbad ordinances, and current building codes, as well as the local area soil conditions. Lateral earth pressures for shoring design are presented as Figure 2. Since the design of retaining systems is sensitive to surcharge pressures behind the excavation, we recommend that this office be consulted if unusual load conditions are uncovered in the placement/installation. To that end, GSI should perform field reviews during shoring construction. Care should be exercised when excavating into the on-site soils since caving or sloughing of the earth materials above the bedrock is possible. Observation of soldier pile excavations and special inspections/testing should be performed during shoring construction. Shoring of the excavation is the responsibility of the contractor. Extreme caution should be used to reduce damage to the existing building or any other adjacent structures caused by settlement or reduction of lateral support. Accordingly, we recommend a system of surveying and monitoring until the permanent building walls are backfilled to the design grade in order to evaluate the effects of shoring on existing onsite and offsite improvements. Pre-construction photo-documentation is also advisable. Unless incorporated into the shoring design, construction equipment storage or traffic, and/or stockpiles should not be stored or operated within 'H' feet of the top of any shored excavations (where 'H' equals the height of the retained earth). Temporary provisions should be made to direct any potential runoff away from the top of shored excavations. All applicable surcharges from vehicular traffic and existing structures within 'H' of a shored excavation should be evaluated. Lateral Pressure 1. The active pressure to be utilized for temporary shoring design may be computed by the triangular pressure distribution shown in Figure 2. 2. Passive pressure for temporary shoring may be computed as an equivalent fluid having a given density shown in Figure 2. 3. The above criteria assumes that hydrostatic pressure is not allowed to build up behind excavation walls. 4. These recommendations are for excavation walls up to 20 feet high. An empirical equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are provided for specific slope gradients of the retained material; these do not include other superimposed loading conditions such as traffic, structures, seismic events, expansive soils or adverse geologic conditions. Traffic surcharge for temporary shoring design should be calculated using a surface surcharge of 100 psf within "H" feet of the top of the wall, BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 52 Cantilever Shoring System / --Surcharge Pressure p (psf) ~---\ --i---Line Load a L (pounds) R- H (feet) D (feet) 35 H (psf) H 0.35 P (psf) I· 400 D (psf) · I --- X 0.1 Y (feet) 0.3 0.5 0.7 X R 5_0.4 0.55 al )0.4 (0.64 al~ x2t 1 / y 0.6H 0.6H 0.56H 0.48H Tie-Back Shoring System _ -Surcharge Pressure P (psf) r \ ---Line Load a L (pounds) } (feet) I · 0.21(ft.) H (feet) istance d this line --Minimum 7' depth for supporting H piers I I® 0.35 P (psf) 400 D (psf) © . . 27 H (psf) 2 Y (feet) NOTES (D Include groundwater effects below groundwater level. ® Include water effects below groundwater level. @ Grouted length greater than 7 feet; field test anchor strength. RIVERSIDE CO. c. ORANGE CO. SAN DIEGO CO. LATERAL EARTH PRESSURES FOR TEMPORARY SHORING © Neglect passive pressure below base of excavation to a depth of i--_____ S __ Y._S_7i_E_M_S ___ Fi_gu_r_e_2~ one pier diameter. W.O. 7535-A-SC DATE 02/19 SCALE None where "H" equals the height of the retained soils. Traffic surcharge from heavy axle load (HS20) vehicles should be minimally applied as 300 psf per lineal foot in the upper 5 feet of the shoring wall(s) if traffic is within "H" feet of the back of the wall, where "H" equals the height of the retained soils. It is not recommended to allow sloping surcharge (other than level backfill) within "2H" behind the shored walls from either stockpiled soils or temporary/permanent graded slopes, where "H" equals the height of the retained soils. Steeper slope gradients (more than level) will increase the EFP for shoring design significantly and impact the cost. Regrading is recommended prior to shoring installation, as needed. 5. When considering nearby improvements located above a 1 :1 (h:v) projection up from the toe of the shored excavation, GSI recommends that a Boussinesq approach be used in the evaluation of surcharge. This approach may model the loads for an estimated vertical load of a footing, and may be used as a line load on the back of the shoring. 6. The shoring system should be designed such thatthe maximum lateral deformation at the top of the soldier pile not exceed 1 inch. The maximum lateral deformation for the shoring soldier piles at the lowest grade level should not exceed½ inch. 7. A braced shoring system may be necessary if a cantilever system is not capable of limiting the herein recommended maximum deflections. Tie-back supports do not appear feasible due to property line restrictions. A rakered/braced shoring system would likely be necessary where the use of tie-back supports is unfeasible. For temporary supports, a maximum allowable bearing of 2,000 psf may be used for a raker footing that is 12 inches wide by 12 inches deep into unweathered stream terrace deposits. The passive pressure used in the design of raker footings which are embedded at 12 inches into unweathered stream terrace deposits may be taken as 150 pcf. This allowable vertical bearing value may be increased by 20 percent for each additional foot of depth to a maximum of 2,500 psf. The coefficient of friction between concrete and soils should be 0.30 when combined with the dead load forces. Shoring Construction Recommendations 1. The excavation and installation of the soldier piles should be observed and documented by the project geotechnical engineer to further evaluate the geologic conditions within the influence of the temporary shoring wall and to ensure the soldier pile construction conforms to the requirements of the shoring plan. 2. Drilled excavations for soldier piles should be straight and plumb. If boulders and cobbles are encountered during drilling, the contractor should periodically recheck the drilled shaft for plumbness. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 54 3. Although not anticipated, casing should be provided in drilled shafts should perched water and/or caving conditions be encountered during drilling operations. The bottom of the casing should be at least 4 feet below the top of the concrete as the concrete is poured and the casing is withdrawn. Although not anticipated, dewatering may be required for concrete placement if significant seepage or groundwater is encountered during construction. This should be considered during project planning. 4. The exacttip elevation of the soldier piles should be clearly indicated on the shoring plans. 5. The mix design of concrete used in the construction of shoring soldier piles should be provided by the shoring design, and should consider the soil corrosivity test results discussed in the "Laboratory Testing" section of this report. All concrete should delivered through a tremie pipe immediately subsequent to approved excavation and steel placement. Care should be taken to prevent striking the walls of the excavations with the tremie pipe during concrete placement. Concrete should not be allowed to free fall more than 5 feet. "Tailgating" concrete will not be permitted. 6. Proper spacing (minimum of 3 inches) between H beams and the side walls, and bottoms of the drilled shafts should be provided 7. Concrete used in the shoring construction should be tested by a qualified materials testing consultant for strength and mix design. 8. Excavation for lagging should not commence until the soldier pile concrete reaches its 28-day compressive strength. 9. A complete and accurate record of all soldier pile locations, depths, concrete, strengths, quantity of concrete per pile should be maintained by the special inspector and geotechnical consultant. The shoring design engineer should be notified of any unusual conditions encountered during installation. Monitoring of Shoring 1. The shoring designer or his designee should make periodic inspections of the job site for the purpose of observing the installation of the shoring system and monitoring of survey. 2. Monitoring points should be established at the top of selected soldier piles and at intermediate intervals as considered appropriate by the Geotechnical Engineer. 3. Control points should be established outside the area of influence of the shoring system to ensure the accuracy of the monitoring readings. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 55 4. Initial monitoring and photographic/video documentation should be performed prior to any excavation. 5. Once the excavation has commenced, periodic readings should be taken weekly until the permanent retaining wall is backfilled to the design grade. If the performance of the shoring system is within established guidelines, the shoring engineer may permit the periodic readings to be bi-weekly. Permission to conduct bi-weekly readings should be provided by the shoring design engineer in writing, and be distributed to the Geotechnical Engineer-of-Record, Structural Engineer-of-Record, Civil Engineer-of-Record, the Building Official, and shoring contractor. Once initiated, bi-weekly readings should continue until the permanent retaining wall is backfilled to the design grade. Thereafter, readings can be made monthly. Additional readings should be taken when requested by the special inspector, Shoring Design Engineer, Structural Engineer-of-Record, Geotechnical Engineer-of-Record, or the Building Official. 6. Monitoring reading should be submitted to the Shoring Design Engineer, Engineer in Responsible Charge, and the Building Official within three business days after they are conducted. Monitoring readings should be accurate to within 0.01 feet. Results are to be submitted in tabular form showing at least the initial date of monitoring and reading, current monitoring date and reading and difference between the two readings. 7. If the total cumulative horizontal or vertical movement (from start of shoring construction) of the existing building reaches½ inch or soldier piles reaches 1 inch, all excavation activities should be suspended until the Geotechnical Engineer and Shoring Design Engineer determine the cause of movement and provide corrective measures, as necessary. Excavation should not re-commence until written permission is provided by the Geotechnical Engineer and Shoring Design Engineer. 8. If the total cumulative horizontal or vertical movement (from start of shoring construction) of any nearby existing improvement reaches½ inch or soldier piles reaches 1 inch, all excavation activities should be suspended until the Geotechnical Engineer and Shoring Design Engineer determine the cause of movement. Supplemental shoring should be devised to eliminate further movement. Supplemental shoring design will require review and approval by the Building Official. Excavation should not re-commence until written permission is provided by the Building Official. Monitoring of Structures 1. The contractor should complete a written and photographic log of existing buildings, streets or other structures located within 100 feet or three times the depth of shoring (whichever is greater) prior to shoring construction. A licensed surveyor BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 56 should document all existing substantial cracks (i.e., greater than 1/a inch horizontal or vertical separation) in the adjacent buildings and structures. 2. The contractor should document the existing condition of distress features within existing improvements located adjacent to the shoring wall, prior to the start of shoring construction. 3. The contractor should monitor existing building walls and improvements for movement or cracking that may result from the adjacent shoring. 4. If excessive movement or visible cracking occurs, the shoring contractor should stop work and shore/reinforce the excavation, and contact the Shoring Design Engineer and the Building Official. 5. Monitoring of the existing building or adjacent structures should be made at reasonable intervals as required by the registered design professional, subject to approval by the Building Official. Monitoring should be performed by a licensed surveyor. 6. Prior to commencing shoring construction, a pre-construction meeting should take place between the contractor, Shoring Design Engineer, Surveyor, Geotechnical Engineer, and the Building Official to identify monitoring locations on existing buildings. 7. If in the opinion of the Building Official or Shoring Design Engineer, monitoring data indicate excessive movement or other distress, all excavation should cease until the Geotechnical Engineer and Shoring Design Engineer investigates the situation and makes recommendations for remedial actions or continuation. 8. All readings and measurements should be submitted to the Building Official and Shoring Design Engineer. ONSITE PRELIMINARY PAVEMENT DESIGN/CONSTRUCTION Structural Section GSI assumed a traffic index (Tl) of 5.0 for the subject onsite drive aisles. This should be confirmed by the project civil engineer prior to final design. A subgrade resistance value (A-value) of 5 was assumed for preliminary planning purposes due to the predominately fine-grained of the existing surficial earth materials. The recommended pavement sections for both asphaltic concrete (AC.) pavement over aggregate base (AB.), and Portland concrete cement pavement (PCCP), are provided in the following tables. Final pavement design should be based on the results of A-value testing, conducting at the conclusion of BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 57 grading and underground utility installation. Please note that the City of Carlsbad may supercede the pavement section recommendations provided herein. ASPHALTIC CONCRETE (AC) PAVEMENTS APPROXIMATE TRAFFIC SUBGRADE A.C. A.B. TRAFFIC AREA INDEX<1> R-VALUE<2> THICKNESS THICKNESS<3> (INCHES) (INCHES) Drive Aisles 5.0 5 4.0 8.0 Drive Aisles with Subgrade Enhancement 5.0 20 3.0 7.0 Geotextile (Tencate Mirafi HP570) (1> The Tl is an estimation based on the intended use and assumes typical light passenger vehicle traffic with occasional truck loads. The Tl should be confirmed by the project civil engineer prior to final design. Trash disposal areas, entry areas, fire vehicle access may require special design detailing. (2> Denotes assumed A-value based on the predominately fine-grained nature of the existing surficial earth materials. Final pavement design should be based on the results of A-value testing, conducting at the conclusion of grading and underground utility installation. (3> Denotes Class 2 Aggregate Base R > 78, SE >25) PORTLAND CONCRETE CEMENT PAVEMENTS (PCCP) TRAFFIC CONCRETE PCCP TRAFFIC CONCRETE PCCP THICKNESS THICKNESS AREAS TYPE (inches) AREAS TYPE (inches) 520-C-2500 7.0 520-C-2500 9.0 Light Vehicles Heavy Truck Traffic 560-C-3250 6.0 560-C-3250 8.0 NOTE: All PCCP is designed as un-reinforced and bearing directly on compacted subgrade. However, a 6-inch thick leveling course of compacted aggregate base may be considered for added support of PCC pavements. All PCCP should be properly detailed Oointing, etc.) per the industry standard. Pavements may be additionally reinforced with #4 reinforcing bars, placed 12 inches on center, each way, for improved performance. Refuse bin enclosure pads shall be a minimum of 7½ inches thick per the City of Carlsbad minimum. All pavement installation, including preparation and compaction of subgrade, compaction of base material, and placement and rolling of asphaltic concrete, etc., shall be done in accordance with under the observation and testing of the project geotechnical consultant. The recommended pavement sections are meant as minimums. If thinner or highly variable pavement sections are constructed, increased maintenance and repair may be needed. The recommended pavement sections provided above are intended as a minimum guideline. If thinner or highly variable pavement sections are constructed, increased maintenance and repair could be expected. If the ADT (average daily traffic) or ADTT (average daily truck traffic) increases beyond that intended, as reflected by the Tl used for design, increased maintenance and repair could be required for the pavement section. Consideration should be given to the increased potential for distress from overuse BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 58 of paved street areas by heavy equipment and/or construction related heavy traffic (e.g., concrete trucks, loaded supply trucks, etc.), particularly when the final section is not in place (i.e., topcoat). Best management construction practices should be followed at all times, especially during inclement weather. Pavement Grading Recommendations General All section changes should be properly transitioned. If adverse conditions are encountered during the preparation of subgrade materials, special construction methods may need to be employed. A GSI representative should be present for the preparation of subgrade, aggregate base, and asphaltic concrete. Subgrade Within drive aisles, all surficial deposits of loose soil material should be removed and re- compacted as recommended. After the loose soils are removed, the bottom is to be scarified to a depth of at least 6 inches, moisture conditioned as necessary and compacted to 95 percent of the maximum laboratory density, as determined by ASTM D 1557. Deleterious material, excessively wet or dry pockets, concentrated zones of oversized rock fragments, and any other unsuitable materials encountered during grading should be removed. The compacted fill material should then be brought to the elevation of the proposed subgrade for the pavement. The subgrade should be proof-rolled in order to promote a uniform firm and unyielding surface. All grading and fill placement should be observed by the project geotechnical consultant. Aggregate Base Compaction tests are required for the recommended aggregate base section. Minimum relative compaction required will be 95 percent of the laboratory maximum density as determined by ASTM D 1557. Base aggregate should be in accordance to the "Greenbook" crushed aggregate base rock (minimum R-value=78). Paving Prime coat may be omitted if all of the following conditions are met: 1. The asphalt pavement layer is placed within two weeks of completion of the aggregate base course. 2. Traffic is not routed over completed base before paving BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 59 3. Construction is completed during the dry season of May through October. 4. The aggregate base is kept free of debris prior to placement of asphaltic concrete. If construction is performed during the wet season of November through April, prime coat may be omitted if no rain occurs between completion of the aggregate base course and paving and the time between completion of aggregate base and paving is reduced to three days, provided the aggregate base is free of loose soil or debris. Where prime coat has been omitted and rain occurs, traffic is routed over the aggregate base course, or paving is delayed, measures shall be taken to restore the aggregate base course, and subgrade to conditions that will meet specifications as directed by the geotechnical consultant. Drainage Positive drainage should be provided for all surface water to drain towards the area swale, curb and gutter, or to an approved drainage channel. Positive site drainage should be maintained at all times. Water should not be allowed to pond or seep into the ground, such as from behind unprotected curbs, both during and after grading. If planters or landscaping are adjacent to paved areas, measures should be taken to minimize the potential for water to enter the pavement section, such as thickened edges, subdrains, enclosed or lined planters, etc. Also, best management construction practices should be strictly adhered to at all times to minimize the potential for distress during construction and roadway improvements. PCC Cross Gutters PCC cross gutters should be designed in accordance with San Diego Regional Standard Drawing (SDRSD) G-12. Additional Considerations To mitigate perched groundwater, consideration should be given to installation of subgrade separators (cut-offs) between pavement subgrade and landscape areas, although this is not a requirement from a geotechnical standpoint. Cut-offs, if used, should be 6 inches wide and at least 12 inches below the pavement subgrade contact or 12 inches below the crushed aggregate base rock, if utilized. PEDESTRIAN PAVEMENTS/FLATWORK AND OTHER IMPROVEMENTS Although not necessarily anticipated, some of the onsite soil materials may be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to pedestrian BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 60 pavements/flatwork and other improvements. The resulting potential for distress to improvements may be reduced, but not totally eliminated. To that end, it is recommended that the developer should notify all interested/affected parties of this long-term potential for distress. To reduce the likelihood of distress, the following recommendations are presented for all exterior flatwork: 1. The subgrade area for non-vehicular concrete slabs should be compacted to achieve a minimum 90 percent relative compaction, and then be presoaked to 2 to 3 percentage points above (or 125 percent of) the soils' optimum moisture content, to a depth of 18 inches below subgrade elevation. If very low expansive soils are present, only optimum moisture content, or greater, is required and specific presoaking is not warranted. The moisture content of the subgrade should be proof tested within 72 hours prior to pouring concrete. Mitigation of any potentially compressible soils within the influence of the hardscape should be performed prior to subgrade preparation. 2. Non-vehicular concrete slabs should be cast over a non-yielding surface, consisting of a 4-inch layer of crushed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete. If very low expansive soils are present, the rock or gravel or sand may be deleted. The layer or subgrade should be wet-down completely prior to pouring concrete, to minimize loss of concrete moisture to the surrounding earth materials. 3. Non-vehicular concrete slabs should be a minimum of 4 inches thick. 4. The use of transverse and longitudinal control joints are recommended to help control slab cracking due to concrete shrinkage or expansion. Two ways to mitigate such cracking are: a) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and, b) provide an adequate amount of control and/or expansion joints to accommodate anticipated concrete shrinkage and expansion . In order to reduce the potential for unsightly cracks, slabs should be reinforced at mid-height with a minimum of No. 3 bars placed at 18 inches on center, in each direction. If subgrade soils within the top 7 feet from finish grade are very low expansive soils (i.e., E.I. ~20), then 6x6-W1 .4xW1 .4 welded-wire mesh may be substituted for the rebar, provided the reinforcement is placed on chairs, at slab mid-height. The exterior slabs should be scored or saw cut, ½ to 3/s inches deep, often enough so that no section is greater than 10 feet by 10 feet. For sidewalks or narrow slabs, control joints should be provided at intervals of every 6 feet. The slabs should be separated from the foundations and sidewalks with expansion joint filler material. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 61 5. No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Concrete compression strength should be a minimum of 2,500 psi. 6. Sidewalks and patio slabs adjacent to the residential structures should be separated from the buildings with thick expansion joint filler material. In areas directly adjacent to a continuous source of moisture (i.e., irrigation, planters, etc.), all joints should be additionally sealed with flexible mastic. 7. Planters and walls should not be tied to the residential structures. 8. Overhang structures should be supported on the slabs, or structurally designed with continuous footings tied in at least two directions. If very low expansion soils are present, footings need only be tied in one direction. 9. Any masonry landscape walls that are to be constructed throughout the property should be grouted and articulated in segments no more than 20 feet long. These segments should be keyed or doweled together. 10. Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. 11. Positive site drainage should be maintained at all times. Finish grade on the property should provide a minimum of 1 to 2 percent fall to the street, as indicated herein or conform to Section 1804.3 of the 2016 CBC (whichever is more conservative). It should be kept in mind that drainage reversals could occur, including post-construction settlement, if relatively flat yard drainage gradients are not periodically maintained by the property caretaker. 12. Air conditioning (A/C) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. A/C waste water lines should be drained to a suitable non-erosive outlet. 13. Shrinkage cracks could become excessive if proper finishing and curing practices are not followed . Finishing and curing practices should be performed per the Portland Cement Association Guidelines. Mix design should incorporate rate of curing for climate and time of year, sulfate content of soils, corrosion potential of soils, and fertilizers used on site. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 62 ONSITE INFILTRATION-RUNOFF RETENTION SYSTEMS General GSI understands that the proposed project qualifies as a Priority Development Project (PDP). Thus, permanent storm water Best Management Practices (BMPs) or Low Impact Development (LID) principles have been incorporated into the project civil design (MLB, 2018) and include the installation of infiltration trenches in the proposed drive aisles. Some guidelines should/must be followed in the planning, design, and construction of proposed infiltration systems because if improperly designed or implemented without consideration of the geotechnical aspects of site conditions, these drainage improvements can contribute to flooding, saturation of bearing materials beneath site improvements, slope instability, and possible concentration and contribution of pollutants into the groundwater or storm drain and/or utility trench systems. The following geotechnical guidelines should be considered when designing the proposed infiltration trenches: • A review of the United States Department of Agriculture/Natural Resources Conservation Service database ([USDA/NRCS]; 1973, 2018) indicates that the surficial soil units mapped at the site consist primarily of the Huerhuero loam, 5 to 9 percent slopes (eroded), and a very small area of localized Altamont clay, 9 to 15 percent slopes. The USDNNRCS indicates the capacity of the most limiting layers of the Huerhuero loam and Altamont clay to transmit water are very low to moderately low (0.00 to 0.06 inches per hour [in/h]), and moderately low to moderately high (0.06 to 0.20 in/hr), respectively. The Hydrologic Soil Group (HSG) for the Huerhuero loam, 5 to 9 percent slopes and Altamont clay, 9 to 15 percent slopes are "D" and "C," respectively. HSG D soils (Huerhuero loam) are generally not compatible with infiltration facilities, and the HSG C soils (Altamont clay) are very limited in areal extent throughout the site (i.e., comprising only approximately 0.3% of the site's surface area and confined to the southwesterly corner of the subject property). • The area of the site to receive the proposed infiltration trenches is underlain by earth materials with low permeability; and therefore, relatively slow infiltration rates. As previously indicated herein, the estimated reliable infiltration rate of soils within area of proposed infiltration trenches with the applied suitability assessment safety factor (SA) of 2.0 is 0.148 in/hr. This infiltration rate supports partial infiltration. However, it is our opinion that if stormwater infiltration were to occur onsite, the infiltrated water would perch upon the less permeable stream terrace deposits or fine-grained fill materials, and then migrate laterally, leading to saturation of fills and backfills, located both onsite and offsite. In response, the weakened fills and backfill could settle. In addition, wetting of expansive soils could induce heave. Both phenomena would likely contribute to improvement distress both onsite and offsite. Therefore, BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 63 stormwater treatment through infiltration is not recommended at the subject site. Rather, stormwater treatment should occur in contained systems (i.e., precast concrete vaults) or utilize deep infiltration, as discussed previously. • Impermeable liners used in conjunction with permanent stormwater BMPs/LIDs should consist of a 30-mil polyvinyl chloride (PVC) membrane that is covered by a minimum of 12 inches of clean soil, free from rocks and debris, with a maximum 4: 1 (h:v) slope inclination, or flatter, and meets the following minimum specifications: Specific Gravity (ASTM D792): 1.2 (g/cc, min.); Tensile Strength at Break (ASTM D882): 73 (lb/in-width, min); Elongation (ASTM D882): 380 (%, min); Modulus at 100 percent (ASTM D882): 32 (lb/in-width, min.); Tear Strength (ASTM D1004): 8 (lbs, min); Seam Strength (ASTM D882): 58.4 (lb/in, min); Seam Shear Strength (ASTM D882): 15 (lbs/in, min.); and Seam Peel Strength (ASTM D882) 2.6 (kN/m, min). The impermeable liner may require periodic maintenance, repair, and/or replacement over the design life of the proposed development. • Subdrains used in conjunction with permanent stormwater BMPs/LIDs should consist of at least 4-inch diameter Schedule 40 or SDR 35 drain pipe with perforations oriented down. The drain pipe should be sleeved with a filter sock. • Drain outlets for stormwater BMPs/LIDs should be tightlined to approved discharge points provided by the project civil engineer. In order to reduce piping failures in soils exterior of the stormwater BMP/LID, a concrete cut-off collar should be provided around the outlet pipe at the exterior of the BMP/LID. The collar should be at least 12 inches wide and extend at least 12 inches beyond the exterior of the outlet/tightline pipe. • Shallow foundations adjacent to permanent stormwater BMPs/LIDs should be deepened such that the top of the footing is located below a 1 :1 (h:v) plane projected up from the lowest invert elevation at the outboard edge of the BMP/LID. Deepened footings are not required if stormwater treatment is to occur in pre-cast concrete vaults, provided the vault is capable of tolerating surcharge imparted by the foundation loads. • As with any stormwater LID/BMP, proper care will need to be provided. Best management practices should be followed at all times, especially during inclement weather. An appropriate inspection schedule will need to adopted and provided to all interested/affected parties. • Any designed system will require regular and periodic maintenance, which may include rehabilitation and/or complete replacement of the filter media (e.g., sand, BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 64 gravel, filter fabrics, liners etc.) or other components utilized in construction, so that the design life exceeds 15 years. • The potential for surface flooding, in the case of system blockage, should be evaluated by the design engineer. DEVELOPMENT CRITERIA Slope Deformation Compacted fill slopes designed using customary factors-of-safety for gross or surficial stability and constructed in general accordance with the design specifications should be expected to undergo some differential vertical heave or settlement in combination with differential lateral movement in the out-of-slope direction, after grading. This post-construction movement occurs in two forms: slope creep, and lateral fill extension (LFE). Slope creep is caused by alternate wetting and drying of the fill soils which results in slow downslope movement. This type of movement is expected to occur throughout the life of the slope, and is anticipated to potentially affect improvements or structures (e.g., separations and/or cracking), placed near the top-of-slope, up to a maximum distance of approximately 15 feet from the top-of-slope, depending on the slope height. This movement generally results in rotation and differential settlement of improvements located within the creep zone. LFE occurs due to deep wetting from irrigation and rainfall on slopes comprised of expansive materials. Although some movement should be expected, long-term movement from this source may be minimized, but not eliminated, by placing the fill throughout the slope region, wet of the fill's optimum moisture content. It is generally not practical to attempt to eliminate the effects of either slope creep or LFE. Suitable mitigative measures to reduce the potential of lateral deformation typically include: setback of improvements from the slope faces (per the 2016 CBC), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. Expansion joints in walls should be placed no greater than 20 feet on-center, and in accordance with the structural engineer's recommendations. All of these measures are recommended for design of structures and improvements. The ramifications of the above conditions, and recommendations for mitigation, should be provided to all interested/ affected parties. Slope Maintenance and Planting Water has been shown to weaken the inherent strength of all earth materials. Slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Over-watering should be avoided as it adversely affects site improvements, and causes perched groundwater conditions. Graded slopes constructed utilizing onsite materials would be erosive. Eroded debris may be BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 65 minimized and surficial slope stability enhanced by establishing and maintaining a suitable vegetation cover soon after construction. Compaction to the face of fill slopes would tend to minimize short-term erosion until vegetation is established. Plants selected for landscaping should be light weight, deep rooted types that require little water and are capable of surviving the prevailing climate. Jute-type matting or other fibrous covers may aid in allowing the establishment of a sparse plant cover. Utilizing plants other than those recommended above will increase the potential for perched water, staining, mold, etc., to develop. A rodent control program to prevent burrowing should be implemented. Irrigation of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to all interested/affected parties. Over-steepening of slopes should be avoided during building construction activities and landscaping. Drainage Adequate surface drainage is a very important factor in reducing the likelihood of adverse performance of foundations, hardscape, and slopes. Surface drainage should be sufficient to mitigate ponding of water anywhere on the property, and especially near structures and tops of slopes. Surface drainage should be carefully taken into consideration during fine grading, landscaping, and building construction. Therefore, care should be taken that future landscaping or construction activities do not create adverse drainage conditions. Positive site drainage within the property should be provided and maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should be directed away from foundations and tops of slopes, and not allowed to pond and/or seep into the ground. In general, finish grade on the property should provide a minimum of 1 to 2 percent fall to the street or other approved areas, or conform to Section 1804.3 of the 2016 CBC (whichever is more conservative). Consideration should be given to avoiding construction of planters adjacent to the residential structure. Building pad drainage should be directed toward the street or other approved area(s). Although not a geotechnical requirement, roof gutters, down spouts, or other appropriate means may be utilized to control roof drainage. Down spouts, or drainage devices should outlet a minimum of 5 feet from structures or into a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy rainfall, and should be anticipated. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon request. Erosion Control Onsite earth materials have a moderate to high erosion potential. Consideration should be given to providing hay bales and silt fences for the temporary control of surface water, from a geotechnical viewpoint. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 66 Landscape Maintenance and Planter Design Only the amount of irrigation necessary to sustain plant life should be provided. Over-watering the landscape areas will adversely affect proposed site improvements. We would recommend that any proposed open-bottom planters adjacent to proposed structures be eliminated for a minimum distance of 10 feet. As an alternative, closed-bottom type planters could be utilized. An outlet placed in the bottom of the planter, could be installed to direct drainage away from structures or any exterior concrete flatwork. If planters are constructed adjacent to structures, the sides and bottom of the planter should be provided with a moisture barrier to prevent penetration of irrigation water into the subgrade. Provisions should be made to drain the excess irrigation water from the planters without saturating the subgrade below or adjacent to the planters. Consideration should be given to the type of vegetation chosen and their potential effect upon surface improvements (i.e., some trees will have an effect on concrete flatwork with their extensive root systems). From a geotechnical standpoint leaching is not recommended for establishing landscaping. If the surface soils are processed for the purpose of adding amendments, they should be recompacted to 90 percent minimum relative compaction. Gutters and Downspouts As previously discussed in the drainage section, the installation of gutters and downspouts should be considered to collect roof water that may otherwise infiltrate the soils adjacent to the structures. If utilized, the downspouts should be drained into PVC collector pipes or other non-erosive devices (e.g., paved swales or ditches; below grade, solid tight-lined PVC pipes; etc.), that will carry the water away from the house, to an appropriate outlet, in accordance with the recommendations of the design civil engineer. Downspouts and gutters are not a requirement; however, from a geotechnical viewpoint, provided that positive drainage is incorporated into project design (as discussed previously). Subsurface and Surface Water Subsurface and surface water are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into final design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities may not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Groundwater conditions may change with the introduction of irrigation, rainfall, or other factors. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 67 Site Improvements If in the future, any additional improvements (e.g., pools, spas, etc.) are planned for the site, recommendations concerning the geological or geotechnical aspects of design and construction of said improvements could be provided upon request. Pools and/or spas should not be constructed without specific design and construction recommendations from GSI, and this construction recommendation should be provided to all interested/affected parties. This office should be notified in advance of any fill placement, grading of the site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench and retaining wall backfills, flatwork, etc. Tile Flooring Tile flooring can crack, reflecting cracks in the concrete slab below the tile, although small cracks in a conventional slab may not be significant. Therefore, the designer should consider additional steel reinforcement for concrete slabs-on-grade where tile will be placed. The tile installer should consider installation methods that reduce possible cracking of the tile such as slipsheets. Slipsheets or a vinyl crack isolation membrane (approved by the Tile Council of America/Ceramic Tile Institute) are recommended between tile and concrete slabs on grade. Additional Grading This office should be notified in advance of any fill placement, supplemental regrading of the site, or trench backfilling after rough grading has been completed. This includes completion of grading in the street, driveway approaches, driveways, parking areas, and utility trench and retaining wall backfills. Footing Trench Excavation All footing excavations should be observed by a representative of this firm subsequent to trenching and prior to concrete form and reinforcement placement. The purpose of the observations is to evaluate that the excavations have been made into the recommended bearing material and to the minimum widths and depths recommended for construction. If loose or compressible materials are exposed within the footing excavation, a deeper footing or removal and recompaction of the subgrade materials would be recommended at that time. Footing trench spoil and any excess soils generated from utility trench excavations should be compacted to a minimum relative compaction of 90 percent, if not removed from the site. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 68 Trenching/Temporary Construction Backcuts Considering the nature of the onsite earth materials, it should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls/backcuts at the angle of repose (typically 25 to 45 degrees [except as specifically superceded within the text of this report]), should be anticipated. All excavations should be observed by an engineering geologist or soil engineer from GSI, prior to workers entering the excavation or trench, and minimally conform to CAL-OSHA, state, and local safety codes. Should adverse conditions exist, appropriate recommendations would be offered at that time. The above recommendations should be provided to any contractors and/or subcontractors, or all interested/affected parties, that may perform such work. Utility Trench Backfill 1. All interior utility trench backfill should be brought to at least 2 percent above optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard. As an alternative for shallow (12-inch to 18-inch) under-slab trenches, sand having a sand equivalent value of 30 or greater may be utilized and jetted or flooded into place. Observation, probing and testing should be provided to evaluate the desired results. 2. Exterior trenches adjacent to, and within areas extending below a 1 :1 plane projected from the outside bottom edge of the footing, and all trenches beneath hardscape features and in slopes, should be compacted to at least 90 percent of the laboratory standard. Sand backfill, unless excavated from the trench, should not be used in these backfill areas. Compaction testing and observations, along with probing, should be accomplished to evaluate the desired results. 3. All trench excavations should conform to CAL-OSHA, state, and local safety codes. 4. Utilities crossing grade beams, perimeter beams, or footings should either pass below the footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade beam in accordance with the recommendations of the structural engineer. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 69 SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend that observation and/or testing be performed by GSI at each of the following construction stages: • During grading. • During excavation, including remedial grading excavations and trenching for underground utilities, bio-retention basins, etc. • During the placement of structural fills. • During placement of subdrains or other subdrainage devices, prior to placing fill and/or backfill. • After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. • Prior to pouring any slabs or flatwork, after presoaking/presaturation of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor retarders (i.e., visqueen, etc.). • During retaining wall subdrain installation, prior to backfill placement. • During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. • During any slope construction/repair. • When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. • When any future improvements, such as flatwork, spas, pools, walls, etc., are constructed, prior to construction. • A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and clear documentation of site work, and/or to comply with code requirements. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 70 OTHER DESIGN PROFESSIONALS/CONSULTANTS The design civil engineer, structural engineer, post-tension designer, architect, landscape architect, wall designer, etc., should review the recommendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plans. This report presents minimum design criteria for the design of slabs, foundations and other elements possibly applicable to the project. These criteria should not be considered as substitutes for actual designs by the structural engineer/designer. Please note that the recommendations contained herein are not intended to preclude the transmission of water or vapor through the slab or foundation. The structural engineer/foundation and/or slab designer should provide recommendations to not allow water or vapor to enter into the structure so as to cause damage to another building component, or so as to limit the installation of the type of flooring materials typically used for the particular application. The structural engineer/designer should analyze actual soil-structure interaction and consider, as needed, bearing, expansive soil influence, and strength, stiffness and deflections in the various slab, foundation, and other elements in order to develop appropriate, design-specific details. As conditions dictate, it is possible that other influences will also have to be considered. The structural engineer/designer should consider all applicable codes and authoritative sources where needed. If analyses by the structural engineer/designer result in less critical details than are provided herein as minimums, the minimums presented herein should be adopted. It is considered likely that some, more restrictive details will be required. If the structural engineer/designer has any questions or requires further assistance, they should not hesitate to call or otherwise transmit their requests to GSI. In order to mitigate potential distress, the foundation and/or improvement's designer should confirm to GSI and the governing agency, in writing, thatthe proposed foundations and/or improvements can tolerate the amount of differential settlement and/or expansion characteristics and other design criteria specified herein. PLAN REVIEW Final project plans (grading, precise grading, foundation, retaining wall, landscaping, etc.), should be reviewed by this office prior to construction, so that construction is in accordance with the conclusions and recommendations of this report. Based on our review, supplemental recommendations and/or further geotechnical studies may be warranted. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 71 LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty, either express or implied, is given. Standards of practice are subject to change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Thus, this report brings to completion our scope of services for this portion of the project. All samples will be disposed of after 30 days, unless specifically requested by the client, in writing. BNR Investment and Development, LLC APN 216-170-14 and -15 File:e:\wp12\7500\7535a.gue GeoSoils, Inc. W.O. 7535-A-SC February 4, 2019 Page 72 APPENDIX A REFERENCES GeoSoils, Inc. APPENDIX A REFERENCES American Concrete Institute, 2014, Building code requirements for structural concrete (ACI 318-14), and commentary (ACI 318R-14): reported by ACI Committee 318, dated September. American Concrete Institute (ACI) Committee 302, 2004, Guide for concrete floor and slab construction, ACI 302.1 R-04, dated June. Allen, V., Connerton, A., and Carlson, C., 2011, Introduction to Infiltration Best Management Practices (BMP), Contech Construction Products, Inc., Professional Development Series, dated December. American Society for Testing and Materials (ASTM), 2003, Standard test method for infiltration rate of soils in field using double-ring infiltrometer, Designation D 3385-03, dated August. __ , 1998, Standard practice for installation of water vapor retarder used in contact with earth or granular fill under concrete slabs, Designation: E 1643-98 (Reapproved 2005). __ , 1997, Standard specification for plastic water vapor retarders used in contact with soil or granular fill under concrete slabs, Designation: E 1745-97 (Reapproved 2004). American Society of Civil Engineers, 2014, Supplement No. 2, Minimum design loads for buildings and other structures, ASCE Standard ASCE/SEI 7-10, dated September 18. __ , 2013a, Expanded seismic commentary, minimum design loads for buildings and other structures, ASCE Standard ASCE/SEI 7-10 (included in third printing). __ , 2013b, Errata No. 2, minimum design loads for buildings and other structures, ASCE Standard ASCE/SEI 7-10, dated March 31. __ , 2013c, Supplement No. 1 , minimum design loads for buildings and other structures, ASCE Standard ASCE/SEI 7-10, dated March 31. __ , 201 Oa, Minimum design loads for buildings and other structures, ASCE Standard ASCE/SEI 7-10. __ , 201 Ob, Structural design of interlocking concrete pavement for municipal streets and roadways, ASCE Standard 58-10. GeoSoils, Inc. Blake, Thomas F., 2000a, EQFAUL T, A computer program for the estimation of peak horizontal acceleration from 3-D fault sources; Windows 95/98 version. __ , 2000b, EQSEARCH, A computer program for the estimation of peak horizontal acceleration from California historical earthquake catalogs; Updated to August 15, 2018, Windows 95/98 version. Bozorgnia, Y., Campbell K.W., and Niazi, M., 1999, Vertical ground motion: Characteristics, relationship with horizontal component, and building-code implications; Proceedings of the SMIP99 seminar on utilization of strong-motion data, September 15, Oakland, pp. 23-49. Bryant, W.A., and Hart, E.W., 2007, Fault-rupture hazard zones in California, Alquist-Priolo earthquake fault zoning act with index to earthquake fault zones maps; California Geological Survey, Special Publication 42, interim revision. California Building Standards Commission, 2016, California Building Code, California Code of Regulations, Title 24, Part 2, Volume 2 of 2, based on the 2015 International Building Code, 2016 California Historical Building code, Title 24, Part 8, 2016 California Existing Building Code, Title 24, Part 10, and the 2015 International Existing Building Code. California Department of Water Resources, 1993, Division of Safety of Dams, Guidelines for the design and construction of small embankments dams, reprinted January. California Stormwater Quality Association (CASQA), 2003, Stormwater best management practice handbook, new development and redevelopment, dated January. Clar, M.L., Bartfield, B.J., O'Conner, T.P., 2004, Stormwater best management practice design guide, volume 3, basin best management practices, US EPN600/R-04/121 B, dated September. County of San Diego, Department of Public Works, 2016, BMP design manual, for permanent site design, storm water treatment and hydromodification management, storm wate requirements for development applications, dated February. Foxlin Architecture, 2018, Resort View Apartments, Viejo Castilla Way, Carlsbas, discretionary review submittal, 22 sheets, various scales, job no.: 1710, dated September 18. GeoSoils, Inc., 2003a, Soil corrosivity results, 7538-7549 Viejo Castilla Way, City of Carlsbad, San Diego County, California, W.O. 4128-A-SC, dated January 12. __ , 2003b, Preliminary geotechnical evaluation, 7538-7549 Viejo Castilla Way, City of Carlsbad, San Diego County, California, W.O . 4128-A-SC, dated December 30. BNR Investment and Development, LLC • File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix A Page 2 Hydrologic Solutions, StormChamber™ installation brochure, pgs. 1 through 8, undated. Jennings, C.W., and Bryant, W.A., 2010, Fault activity map of California, scale 1 :750,000, California Geological Survey, Geologic Data Map No. 6. Kanare, H.M., 2005, Concrete floors and moisture, Engineering Bulletin 119, Portland Cement Association. Kennedy, M.P., and Tan, SS., 2007, Geologic map of the Oceanside 30' by 60' quadrangle, California, regional map series, scale 1: 100,000, California Geologic Survey and United States Geological Survey, www.conservation.ca.gov/ cgs/rghm/rgm/prel iminary _geologic_ maps. html MLB Engineering, 2018, Title sheet and preliminary grading plan for: Resort View, Viejo Castilla Way, APNs 216-170-14 & -15 2 sheets, 20-scale, various scales dated October 18. Post-Tensioning Institute, 2014, Errata to standard requirements for design and analysis of shallow post-tensioned concrete foundations on expansive soils, PTI DC10.5-12, dated April 16. __ , 2013, Errata to standard requirements for design and analysis of shallow post-tensioned concrete foundations on expansive soils, PTI DC10.5-12, dated November 12. __ , 2012, Standard requirements for design and analysis of shallow post-tensioned concrete foundations on expansive soils, PTI DC10.5-12, dated December. __ , 2008, Design of post -tensioned slabs-on-Ground, Third Edition. __ , 2004, Design and construction of post-tensioned slabs-on-ground, 3rd edition, Phoenix, AZ. Romanoff, M., 1957, Underground corrosion, originally issued April 1. Seed, 2005, Evaluation and mitigation of soil liquefaction hazard "evaluation of field data and procedures for evaluating the risk of triggering (or inception) of liquefaction", in Geotechnical earthquake engineering; short course, San Diego, California, April 8-9. Sowers and Sowers, 1979, Unified soil classification system (After U. S. Waterways Experiment Station and ASTM 02487-667) in Introductory Soil Mechanics, New York. State of California, 2019, Civil Code, Sections 895 et seq. BNR Investment and Development, LLC • File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix A Page 3 State of California Department of Transportation, Division of Engineering Services, Materials Engineering, and Testing Services, Corrosion Technology Branch, 2003, Corrosion Guidelines, Version 1 .0, dated September. Tan, S.S. and Giffen, D.G., 1995, Landslide hazards in the northern part of the San Diego metropolitan area, San Diego County, California, DMG open file report 95-04, landslide hazard identification map no. 35, relative landslide susceptibility and landslide distribution map, plate 35D, 1 :24,000 scale. United States Geological Survey, 2014, U.S. Seismic Design Maps, Earthquake Hazards Program, http://geohazards.usgs.gov/designmaps/us/application.php, updated June 23, 2014. __ , 1999, Encinitas quadrangle, San Diego County, California, 7.5 minute series, 1 :24,000 scale. Wire Reinforcement Institute, Inc., 1996, Design of slab-on-ground foundations, a design, construction & inspection aid for consulting engineers, an update, dated March (Copyright 2003). BNR Investment and Development, LLC • File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix A Page 4 Geotechnical • Geologic • Environmental 5741 Palmer Way° Carlsbad, California 92008 ° (760)438-3155 ° FAX (760) 931-0915 • January 12, 2004 Mr. Ram Setya c/o Karnak Architecture and Planning 2802 State Street, Suite C Carlsbad, California 92008 Attention: Mr. Robert Richardson W.O. 4128-A-SC Subject: Soil Corrosivity Results, 7538-7549 Viejo Castilla Way, City of Carlsbad, San Diego County, California References: 1. "Preliminary Geotechnical Evaluation, 7538-7549 Viejo Castilla Way, City of Carlsbad, San Diego County, California," W.O.4128-A-SC, dated December 30, 2003, by GeoSoils, Inc. - 2. "Uniform Building Code," Whittier, California, Vol. 1, 2, and 3, 1997, by International Conference of Building Officials. Dear Mr. Richardson: As discussed in Reference No. 1, GeoSoils, Inc. (GSI), conducted sampling of representative soils on the subject site for corrosivity. Laboratory test results were completed by M.J. Schiff (consulting corrosion engineers). Unless specificallysuperceded herein, the con-clusions and recommendations contained in the referenced report by GSI remain pertinent and applicable, and should be appropriately implemented during design and construction. SUMMARY A typical sample of the site materials was analyzed for corrosion/acidity potential (attached as Figure 1 , following the text of this letter). The testing included determination of soluble sulfates, pH, and saturated resistivity. Results are as follows: site soils are generally mildly alkaline (pH of 7.5), are moderately corrosive to metals (i.e., 9,600 ohms-cm), and have a negligible potential for sulfate exposure to concrete (i.e., less than 0.01 soluble sulfate percent by weight in soil). Alternative methods and additional comments should be obtained from a qualified corrosion engineer. DG/JPF/DWS/jh Attachment: Figure 1 -Corrosion Test Results Distribution: (4) Addressee Mr. Ram Setya 7538-7549 Viejo Castilla Way, Carlsbad File:e:\wp9\4100\4128a.scr GeoSoils, lne .. Reviewed by: ~I) David W. Skelly Civil Engineer, RCE 47857 · W.0. 4128-A-SC January 12, 2004 Page2 M. J. Schiff & Associates, Inc. Cons11lting Corrosion Engi11ctr.t. Since l.95.'> ,IJ/ W. 811selint! Rt1ad Claremont, CA 91 ii I P//nn~: (909) 616-Q967 Fax: (909) 626-JJ/6 E-mail/ab(fi).,mjschiff.cnm web.'ilte: mj.rcl1iff.cum Sample ID Rei.i:;llvit.y as-received saturarcd pH Elei:tritnl Conductivity Chemical Analy~e$ Cntions calcium Cn2•• magnesium Mg2'· sodium Na11· Anion~ carbonocc cot Table 1 -Laboratory Tests on Soil Samples Setya Units ohm-cm ohm-cm mStcm mg/kg mg/kg mg/kg m.glkg 'fo11r #41.28-.4.-SC, MJS&A /l(}_~-15511.AB 2-Jn11-04 TP-1 79.000 9,600 7.5 0.0,5 12 ND 6 ND bicarbonate HC011• mg/kg 52 chloride c11• mg/kg ND sulfate so/ mg/kg ND Other Te,b ammonium NH/' mg/kg na nitrnte NO/ mg/kg na sulfide sl• qual na R~dox mv .mt Electrical conductivity in millisiem.en$/Cm and chemicnl analysis were mode on a 1:5 soil-to-water extract. mg/kg = milligrams per kilogram (parts per million) of dry soil. Redox = oxidation-reducti(ln potential in millivolts NI) = no1 detected na = not analyzed Figure 1 Pngc I of I PRELIMINARY GEOTECHNICAL EVALUATION 7538-7549 VIEJO CASTILLA WAY CITY OF CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA FOR MR. RAM SETYA c/o KARNAK ARCHITECTURE AND PLANNING 2802 STATE STREET, SUITE C --CARLSBAD, CALIFORNIA 92008 W.O. 4128-A-SC DECEMBER 30, 2003 Geotechnical • Coastal • Geologic • Environmental 5741 Palmer Way • Carlsbad,. California 92010 • (760) 438-3155 • FAX (760) 931-0915 December 30, 2003 W.O. 4128-A-SC Mr. Ram Setya c/o Karnak Architecture and Planning 2802 State Street, Suite C Carlsbad, California 92008 ·Attention: Subject: Mr. Robert Richardson Preliminary Geotechnical Evaluation, 7538-7549 Viejo Castilla Way, City of Carlsbad, San Diego County, California Dear Mr. Richardson: In accordance with your request, GeoSoils, Inc. (GSI) has performed a preliminary geotechnical evaluation of the subject site. The purpose of the study was to evaluate the onsite soils and geologic conditions and their effects on the proposed site development from a geotechnical viewpoint. EXECUTIVE SUMMARY Based on our review of the available data (see Appendix A), field exploration, laboratory testing, and geologic and engineering analysis, residential development of the property appears to be feasible from a geotechnical viewpoint, provided the recommendations presented in the text of this report are properly incorporated into the design and construction of the project. The most significant elements of this study are summarized below: • The proposed development will consist of two residential structures with basement/garage sub-floors and two additional stories above the sub-floors, as well as underground utility improvements and associated driveways. • Excavation into Quaternary-age Sweitzer Formation, stream terrace deposits will be necessary prior to foundation construction of the basement sub-floor. In general, unsuitable soils are on the order of ±3 to ± 7 feet thick across a majority of the site. However, localized deeper removals cannot be precluded. It is anticipated that the removal of unsuitable bearing materials will be performed by default during excavation for the garage/basement to design grades, and thus, should not adversely affect proposed superjacent improvements; however, settlement sensitive improvements outside of the limits of planned excavation will also require mitigation in the form of remedial removals. • The expansion potential of tested on site soils ranges from very low to high; thus, the potential for highly expansive soil exposed at finish grade cannot be precluded. Owing to the nature of expansive soils, some potential for distress to flatwork and improvements should be anticipated. This information should be disclosed to all· interested parties by the developer. Recommendations for conventional foundations and post-tension foundations are provided herein. . • Foundation systems should be designed to accommodate a worst-case differential settlement of at least 1 inch in a 40-foot span. Post-tension foundations are recommended for soils within an expansion index (E.I.) greater than 90. • Atthe time of this report, corrosion testing results had not been received from the lab for the subject site. An addendum report presenting those results will be provided when lab testing is complete. • Our evaluation indicates that proposed temporary construction slopes onsite may generally be considered surficially unstable, and may require shoring. Preliminary recommendations for shoring are provided herein. • In general, and based upon the available data to date, groundwater is not expected to be a major factor in development of the site; however, perched water may occur during construction and/or after site development. • Exterior basement walls should be waterproofed. If gravel backdrains for the basement walls are proposed, the drains should outlet via a moisture-activated sump pump. In lieu of backdrains, the basement walls may be designed to withstand the increased hydrostatic pressure. Such design criteria may be provided upon request. • Our evaluation indicates that the site has a very low potential for liquefaction. Therefore, no recommendations for mitigation are deemed nec·essary. • Our evaluation indicates there are no known active faults crossing the site. • The seismic acceleration values and design parameters provided herein should be considered during the design of the proposed development. • Adverse geologic features that would preclude project feasibility were not encountered. • The recommendations presented in this report should be incorporated into the design and construction considerations of the project. Mr. Ram Setya File:e:\wp9\4100\4128a.pge W.O. 4128-A-SC Page Two The opportunity to be of service is greatly appreciated. If you have any questions concerning this report or if we may be of further assistance, please do not hesitate. to contact the undersigned. Respectfully submitted .~?< __ €._D---.;: r'\,V GeoSoils, Inc. f~ .;.,; DONNAGO \--l .. -... \ 1 NO. i o Donna Gooley Project Geologist, Reviewed by: ; j, 1 ... 6 .. . :, NO. 134 Co.r,ti!.i~ · Ef.!J;~rJ&,sr! John. P. Franklin ° ·" Engineering Geolo DG/ JPF/DWS/jk Distribution: (4) Addressee Mr. Ram Setya File:e:\wp9\4100\4128a.pge Reviewed by: W.O. 4128-A-SC Page Three TABLE OF CONTENTS SCOPE OF SERVICES .................................................... 1 SITE CONDITIONS/PROPOSED DEVELOPMENT .............................. 1 SITE EXPLORATION ...................................................... 1 REGIONAL GEOLOGY ................................................... 4 SITE GEOLOGIC UNITS .................................................. 4 Artificial Fill -Undocumented (Map Symbol -afu) ......................... 4 Topsoil/Colluvium (Not Mapped) ...................................... 4 Quaternary-age Sweitzer Formation, Stream Terrace Deposits (Map Symbol -Qsst) ........................................... 5 FAUL TING AND REGIONAL SEISMICITY .............................. ; ...... 5 Faulting .......................................................... 5 Se1sm1c1ty ........................................................ 7 Seismic Shaking Parameters ......................................... 7 Seismic Hazards ................................................... 8 GROUNDWATER ........................................................ 8 LABORATORY TESTING .................................................. 9 General ........ · .................................................. 9 Classification ...................................................... 9 Moisture-Density Relations .......................................... 9 Laboratory Standard .............................. : ................. 9 Expansion Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 o Atterberg Limits ................................................ , . . 1 O Direct Shear Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 o Corrosion/Sulfate Testing ........................................... 11 CONCLUSIONS ........................................................ 11 EARTHWORK CONSTRUCTION RECOMMENDATIONS ....................... 11 General .......................................................... 11 Site Preparation ............................................. : . . . . 12 Removals (Unsuitable Surficial Materials) .............................. 12 Fill Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Transitions/Overexcavation ......................................... 12 Temporary Construction Slopes ..................................... 12 · Preliminary Shoring Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 General ..................................... · .............. 13 Lateral Pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Design of Soldier Piles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Lagging ................................................... 14 Internal Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Deflection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Monitoring .................................................. 14 CONVENTIONAL FOUNDATION RECOMMENDATIONS ....................... 14 Design .......................................................... 14 Slope Setback Considerations for Footings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Foundation Settlement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 · Construction -Cqnventional Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Very Low to Low Expansive Soils (E.1. 0-50) ............................ 16 Medium Expansive Soils (E.I. 51-90) .................................. 17 PRELIMINARY POST-TENSIONED SLAB FOUNDATION SYSTEMS .............. 17 General .......................................................... 18 Post-Tensioning Institute Method ..................................... 18 UTILITIES ............................................................. 20 · WALL DESIGN PARAMETERS CONSIDERING EXPANSIVE SOILS ............... 20 Conventional Retaining Walls ....................................... 20 Restrained Walls ............................................ 20 Cantilevered Walls ........................................... 20 Retaining Wall Backfill and Drainage : ................................. 21 Wall/Retaining Wall Footing Transitions ............................... 25 TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS AND EXPANSIVE SOILS ...... 25 Expansive Soils and Slope Creep .................................... 25 Top of Slope Walls/Fences ......................................... 26 EXPANSIVE SOILS, DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS ...... 27 DEVELOPMENT CRITERIA ............................................... 29 Slope Deformation ................................................ 29 Slope Maintenance and Planting ..................................... 29 Drainage ........................................................ 30 Erosion Control ................................................... 30 Landscape Maintenance ........................................... 30 Gutters and Downspouts ........................................... 31 Subsurface and Surface Water ...................................... 31 Site Improvements ................................................ 31 Tile Flooring ..................................................... 32 Additional Grading ................................................ 32 Footing Trench Excavation ......................................... 32 Trenching ....................................................... 32 Utility Trench Backfill .............................................. 32 Mr. Ram Setya File:e:\wp9\4100\4128a.pge Table of Contents Page ii SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING ............ · ............................................. 33 OTHER DESIGN PROFESSIONALS/CONSULTANTS .. · ........................ 34 PLAN REVIEW ......................................................... 34 LIMITATIONS .......................................................... 34 FIGURES: Figure 1 -Site Location Map ......................................... 2 Figure 2 -Test Pit Location Map ...................................... 3 Figure 3 --California Epicenter Map .................................... 6 Detail 1 -Typical Retaining Wall backfill and Drainage Detail .............. 22 Detail 2 .-Retaining Wall Backfill and Subdrain detail Geotextile Drain ....... 23 Detail 3 -Retaining Wall and Subdrain Detail Clean Sand Backfill ........... 24 ATTACHMENTS: Appendix A-References ................................... Rear of Text Appendix B -Test Pit Logs .................................. Rear of Text Appendix C -EQFAULT .................................... Rear of Text Appendix D -General Earthwork and Grading Guidelines ......... Rear of Text Mr. Ram Setya File:e:\wp9\4100\4128a.pge Table of Contents Page iii PRELIMINARY GEOTECHNICAL EVALUATION 7538-7549 VIEJO CASTILLA WAY CITY OF CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA SCOPE OF SERVICES The scope of our services has included the following: 1. Review of the available geologic literature for the site (see Appendix A). 2. Geologic site reconnaissance, subsurface exploration, sampling and mapping. 3. Appropriate laboratory testing of representative soil samples. 4. General areal seismicity evaluation. 5. . Engineering and geologic analysis of data collected. 6. Preparation of this report and accompaniments. SITE CONDITIONS/PROPOSED DEVELOPMENT The site consists of a rectangular, gently northward sloping property, located on the west side of Viejo Castilla Way, in the City of Carlsbad, California (see Figure 1, Site Location Map). The property is currently vacant. The site is located approximately 102 to 121 feet above Mean Sea Level (MSL). The southwest portion of the property consists of a natural mound approximately 18 feet higher than the rest of the site. Site development is anticipated to consist of preparing the site for the construction of two residential structures with basement/garage sub-floors and two additional stories above the sub-floors, as well as underground utility improvements and driveways. Building loads are assumed to be typical for this type of relatively light construction. It is anticipated that sewage disposal will be tied ·into the regional municipal system. The need for import soils is unknown. SITE EXPLORATION Surface observations and subsurface exploration were performed on December 15, 2003, by a representative of this office. A survey of line and grade for the subject site was not conducted by this firm at the time of our site reconnaissance. Near surface soil conditions were explored with four exploratory test pits excavated with a backhoe within the site to evaluate soil and geologic conditions. The approximate location of each test pit is shown on the Test Pit Location Map (Figure 2). Test Pit Logs are presented in Appendix B. 3-D TopoQuads C11pylight © 1999 DeLorme Yarmouth, ME 041)96 ' ' ' ' t\ ~- . ~l---' ' ,, ,_../·'~ . I ~i--~ffi!ii.li.=•\.:1',>'~41:f.!: ' . ....~ ' .:.t ---:: i!U~\8':i',"~:1$~~ ...... ~ '"" • •-W.. .-,.!rt'.W~ h Base Map: The Thomas Guid~, San Diego County Street Guide and Directory, 2002 Edition, by Thomas Bros .. Maps, pages 1127 and 1147, 1":1/2 mile Base Map: Encinitas Quadrangle, California--San Diego Co.; 7.5 Minute Series (Topographic), 1968 (phot revised 1975), by us·Gs, 1"=2000' Reproduced with permiasion~ranted by Thomas Bros. Maps. Thi• m•p la copyrighted by ThomH Broa. Mapa. It la unlawful to copY, or reproduce an· or any part thereof, whether for personal use or resale, without permission. All rights reserved. • N w.o. 4128-A-SC SITE LOCATION MAP Figure 1 \ I I NOT A PART IL--afu CiTP-2 qi---0 1J' ~I ,_ -........{ TP-3 IA,," i/ . ' : \ ill -(--,,~ _ ~r -- ' afu I TP-4 ~'-1 IA I "TP-1 r asst 1 I I ' ~iq~ I i I -<{ . _J ...I ~ < "f. \,) 133 Q I~ ~ 5 ;z -,_ :.J' /· ,, _1· ~ -----·~~:zl ___ "'___ --~ afu asst LEGEND Und.ocumente·d artificial fill •··:,r·,·1•~••. ,,. ·•~\: . ·a , ~~~oo uaternary-age Sweitzer Formation, oRANGEco: .. stream ·terrace . deposits .. sAt;i o1eGo.co. . ! .. •••···•. •-~.~.,1 {,'•'·~:,-.:r.::~••'~,,._.-,ill• ',; ; -----Approximate location of geologic contact TEST i:>IT 1-.0CATION ... l'! TP;,4 .Approi<imate location of exploratory test pit · • .·;:, ..... :... .MAP .. J;is!ite.2; · .• 1 ;w;odJ:1g!hA.:S~ .. ;-ttc\t:e,~"?.t9~trr;s6iLe·.:,!~gg;'. REGIONAL GEOLOGY The subject property is located within a prominent natural geomorphic province in southwestern California known as the Peninsular Ranges. It is characterized by steep, elongated mountain ranges and valleys that trend northwesterly. The mountain ranges are underlain by basement rocks consisting of pre-Cretaceous metasedimentary rocks, Jurassic metavolcanic rocks, and Cretaceous plutonic rocks of the southern California batholith. In the San Diego County region, deposition occurred during the Cretaceous Period of the Cenozoic Era in the continental margin of a forearc basin. Sediments, derived from Cretaceous-age plutonic rocks and Jurassic-age volcanic rocks, were deposited into the narrow, steep, coastal plain and continental margin of the basin. These rocks have been uplifted, eroded and deeply incised. During early Pleistocene time, a broad coastal plain was developed from the deposition of marine terrace deposits. During mid-to late- Pleistocene time, this plain was uplifted, eroded and incised. Alluvial deposits have since filled the lower valleys, and young marine sediments are currently being deposited/eroded within coastal and beach areas. SITE GEOLOGIC UNITS The site geologic units encountered during our subsurface investigation and site reconnaissance included undocumented artificial fill, topsoil/colluvium, and Sweitzer Formation, stream terrace deposits. The earth materials are generally described below from the youngest to the oldest. The distribution of these materials is shown on Figure 2. Artificial Fill -Undocumented (Map Symbol -afu) Undocumented artificial fill was observed at the surface in Test Pits TP-1, 2, and 3. The undocumented fill is probably derived from the construction of the existing nearby development located to the south of the site. The artificial fill is comprised of a greenish gray silt that was observed to be non-uniform, moist, soft, and porous. The observed thickness of the fill material was on the order of 1 to 2 feet. These materials are considered potentially compressible in their existing state and will require removal and recompaction, if settlement sensitive improvements are proposed within their influence. Topsoil/Colluvium (Not Mapped) Topsoil/colluvium, consisting of red brown, moist, loose/stiff, clayey sand to clay to sandy clay, approximately 1 to 2 feet thick, was encountered onsite. These soils are considered potentially compressible in their existing state and will require removal during any future grading within the site, if settlement sensitive improvements are proposed in those areas. The earth materials can be reused as compacted fill, provided deleterious material has been removed. Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 Page4 Quaternary-age Sweitzer Formation, Stream Terrace Deposits (Map Symbol -Qsst) Stream terrace deposits of the Sweitzer Formation were observed to underlie the site and consist generally of loose to medium dense (with depth) silty sands with cobbles, to soft to very stiff (with depth) silt to clay. These deposits are generally red brown in color, and moist to wet. The upper 2 to 5 feet of these materials are generally weathered and considered unsuitable for structural support in their present condition and should be removed and recompacted, should settlement sensitive improvements be proposed within their influence. Locally, these deposits were observed to be friable to a depth of approximately 9 feet.· Temporary construction slopes onsite may be surficially unstable and may require shoring. Recommendations for shoring are provided herein. FAUL TING AND REGIONAL SEISMICITY Faulting The site is situated in, a region of active as well as potentially-active faults. Our review indicates that there are no known active faults crossing the site within the areas proposed for development (Jennings, 1994), and the site is not within an Earthquake Fault Zone (Hart and Bryant, 1997). There are a number of faults in the southern California area that are considered active and would have an effect on the site in the form of ground shaking, should they be the source of an earthquake (see Figure 3, Earthquake Epicenter Map). These faults include, but are not limited to: the San Andreas fault; the San Jacinto fault; the Elsinore fault; the Coronado Bank fault zone; and the Newport-Inglewood -Rose Canyon fault zone. The possibility of ground acceleration or shaking at the site may be considered as approximately similar to the southern California region as a whole. The following table lists the major faults and fault zones in southern California that could have a significant effect on the site should they experience significant activity. Coronado Bank-Agua Blanca Elsinore-Temecula Newport-Inglewood-Offshore Rose Canyon Elsinore-Julian Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge 21.4(39.2 24.4(39.2) 11.5 (18.5) 6.5 (10.4 24.4(39.2) W.O. 4128-A-SC December 30, 2003 Page5 EARTHQUAKE EPICENTER MAP Viejo Castilla 1100 --rr------------------------------, 1000 900 800 700 600 500 400 300 200 100 LEGEND X M=4 Q M=5 0 M=6 D, M=7 0 ◊M=8 -100 --I-J.....L...l--'-1-'--'--'--'-1-....L...l--'-L-!--...._._.J....L-f-'-....L...l--'-f-l--"'-'---'-l--'--'---'-"'-+-=.,_..L.«L-f-'-....L...l--'-1--'-.,__._--'--I -400 -300 -200 -100 0 100 200 300 400 500 600 W .0. 4128-A-SC Figure 3 Seismicity The acceleration-attenuation relations of Sadigh, et al. (1997) Horizontal Soil, Bozorgnia, Campbell and Niazi (1999) Horizontal-Soft Rock-Correlation and Campbell and Bozorgnia (1997 Rev.) Horizontal-Soil have been incorporated into EQFAUL T (Blake, 2000a). For this study, peak horizontal ground accelerations anticipated at the site were determined based on the random mean plus 1 -sigma attenuation· curve and mean attenuation curve developed by Joyner and Boore.(1981, 1982a, 1982b, 1988, 1990), Bozorgnia, Campbell, and Niazi (1999), and Campbell and B.ozorgnia (1997). EQFAUL Tis a computer program by Thomas F. Blake (2000a), which performs deterministic seismic hazard analyses using up to 150 digitized California faults as earthquake sources. The program estimates the closest distance between each fault and a given site. If a fault is found to be within a user-selected radius, the program estimates peak horizontal ground acceleration that may occur at the site from an upper bound ("maximum credible") earthquake.on lhat fault. Site acceleration (g) is computed by one of many user-selected acceleration-attenuation relations that are contained in EQFAULT. Based on the EQFAULT program, peak horizontal ground accelerations from an upper bound event at the site may be on the order of 0.47g to 0.56g. Historical site seismicity was evaluated with the acceleration-attenuation relations of Campbell and Bozorgnia (1997 Revised) Soft Rock and the computer program EQSEARCH (Blake, 2000b). This program performs a search of the historical earthquake records for magnitude 5.0 to 9.0 seismic events within a 100-mile radius, between the years 1800 to 2002. Based on the selected acceleration-attenuation relationship, a peak horizontal ground acceleration is estimated, which may have effected the site during the specific event listed. Based on the available data and the attenuation relationship used, the estimated maximum (peak) site acceleration during the period 1800 to 2002 was 0.44g. Site specific probability of exceeding various peak horizontal ground accelerations and a seismic recurrence curve are also estimated/generated from the historical data. Computer printouts of pertinent portions of the EQSEARCH program are presented in Appendix C. A probabilistic seismic hazards analyses was performed using FRISKSP (Blake, 2000c) which models earthquake sources as 3-D planes and evaluates the site specific probabilities of exceedance for given peak acceleration levels or pseudo-relative velocity levels. Based on a review of these data, and considering the relative seismic activity of the southern California region, a peak horizontal ground acceleration of 0.35g was calculated. This value was chosen as it corresponds to a 1 o percent probability of exceedance in 50 years (or a 475-year return period). Seismic Shaking Parameters Based on the site conditions, Chapter 16 of the Uniform Building Code ([UBC], International Conference of Building Officials [ICBO], 1997), the following seismic parameters are provided. Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 Page7 Seismic zone (per Figure 16-2*) 4 Seismic Zone Factor (per Table 16-1*) 0.40 Soil Profile Type (per Table 16-J*) So Seismic Coefficient Ca (per Table 16-Q*) 0.44 Na Seismic Coefficient Cv (per Table 16-R*) 0.64 NV Near Source Factor Na (per Table 16-S*) 1.0 Near Source Factor Nv (per Table 16-T*) 1.0 S_eismic Source Type (per Table 16-U*) B Distance to Seismic Source 6.5mi. (10.4 km) Upper Bound Earthquake [Rose Canyon] Mw6.9 * Figure and table references from Chapter 16 of the UBC (ICBO, 1997). Seismic Hazards The following list includes other seismic related hazards that have been considered during our evaluation of the site. The hazards listed are considered negligible and/or completely mitigated as a result of site location, soil characteristics and typical site development procedures: • Liquefaction • Tsunami • Dynamic Settlement • Surface Fault Rupture • Ground Lurching or Shallow Ground Rupture • Sieche It is important to keep in perspective that in the event of a maximum probable or credible earthquake occurring on any of the nearby major faults, strong ground shaking would occur in the subject site's general area. Potential damage to any structure(s) would likely be greatest from the vibrations and impelling force caused by the inertia of a structure's mass, than from those induced by the hazards considered above. This potential would be no. greater than that for other existing structures and improvements in the immediate vicinity. GROUNDWATER Subsurface water was not encountered within the property during field work performed in preparation of this report. Subsurface water is not anticipated to adversely affect site development, provided that the recommendations contained in this report are incorporated into final design and construction. These observations reflect site conditions at the time of Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\412Ba.pge W.O. 4128-A-SC December 30, 2003 PageB our investigation and do not preclude future changes in local groundwater conditions from excessive irrigation, precipitation, or that were not obvious, at the time of our investigation. Regional groundwater is estimated to be at least 50 feet in depth, below the site. Seeps, springs, or other indications of a high groundwater level were not noted on the subject property during the time of our field investigation. However, seepage may occur locally (as the result of heavy precipitation or irrigation) in areas where any fill or permeable soils overlie stream terrace deposits or impermeable soils. Such conditions may occur during grading or after the site is developed. LABORATORY TESTING General Laboratory tests were performed on representative samples of the onsite earth materials in order to evaluate their physical characteristics. The test procedures used and results obtained are presented below. Classification · Soils were classified visually according to the Unified Soils Classification System (USCS). The soil classifications are shown on the Test Pit Logs in Appendix B. Moisture-Density Relations The field moisture contents and dry unit weights was determined for a selected undisturbed sample in the laboratory. The dry unit weight was determined in pounds per cubic foot (pcf), and the field moisture content was determined as a percentage of the dry weight. The results of these tests are shown on the Test Pit Logs in Appendix B. Laboratory Standard The maximum dry density and optimum moisture content was determined for the major soil type encountered in the borings. The laboratory standard used was ASTM D-1557. The moisture-density relationship obtained for this soil is shown below: Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 Page9 SILTY SAND, Red Brown TP-1 @5 115.5 11.5 SANDY CLAY, Dark Brown TP-2@3 122.5 11.0 Expansion Potential Expansion testing was performed on representative samples of site soil in accordance with UBC Standard 18-2. The results of expansion testing are presented in the following table. TP-1 @5' 1 Very Low TP-2@3' 91 High Atterberg Limits Tests were performed on soils exhibiting high expansion potentials (i.e., Expansion Index [E.1.] between 91 and 130), per 1997 UBC requirements, to evaluate the liquid limit, plastic limit, and plasticity index in general accordance with ASTM D4318. The test results are presented below: TP-2@3 53 20 Direct Shear Test Shear testing was performed on representative, undisturbed samples of site soil in general accordance with ASTM Test Method D-3080 in a Direct Shear Machine of the strain control type. The shear test results are as follows: Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 Page 10 TP-1 @4' 88 38 42 39 TP-2@7' 1618 26 1576 27 Corrosion/Sulfate Testing Laboratory test results for soluble sulfates, pH, and corrosion to metals have not been received as of the date of this report. Testing will be presented as an addendum upon receipt of the results. Additional testing of site materials is recommended when proposed grading is complete to verify the findings. · CONCLUSIONS Based upon our site reconnaissance, subsurface exploration, and laboratory test results, it is our opinion that the subject site appears suitable for the proposed residential development. The following recommendations should be incorporated into the construction details. EARTHWORK CONSTRUCTION RECOMMENDATIONS General All grading should conform to the guidelines presented in Appendix Chapter A33 of the UBC, the requirements of the City, and the Grading Guidelines presented in Appendix D, except where specifically superceded in the text of this report. Prior to grading, a GSI representative should be present at the preconstruction meeting to provide additional grading guidelines, if needed, and review the earthwork schedule. During earthwork construction all site preparation and the general grading procedures of the contractor should be observed and the fill selectively tested by a representative(s) of GSI. If unusual or unexpected conditions are exposed in the field, they should be reviewed by this office and if warranted, modified and/or additional recommendations will be offered. All applicable requirements of local and national construction and general industry safety orders, the Occupational Safety and Health Act, and the Construction Safety Act should be met. Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December30,2003 Page 11 Site Preparation Debris, vegetation, existing structures, and other deleterious material should be removed from the building area prior to the start of construction. Sloping areas to receive fill should be properly benched in accordance with current industry standards of practice and guidelines specified in the UBC. Removals {Unsuitable Surficial Materials} Due to the relatively loose condition of undocumented artificial fill, topsoil/colluvium, and weathered stream terrace deposits, these materials should be removed and recompacted in areas proposed for settlement sensitive structures or areas to receive compacted fill. At this time, removal depths on the order of 3 to 7 feet (including artificial fill, topsoil/colluvium, and weathered stream terrace deposits) below existing grade should be anticipated throughout a majority of the site; however, locally deeper removals cannot be precluded. Removals should be completed below a 1: 1 projection down and away from the edge of any settlement sensitive improvements and/or limits of proposed fill. Once removals are completed, the exposed bottom should be reprocessed ctnd compacted to 90 percent relative compaction. Fill Placement Subsequent to ground preparation, onsite_ soils may be placed in thin (±6-inch) lifts, cleaned of vegetation and debris, brought to a least optimum moisture content, and compacted to achieve a minimum relative compaction of 90 percent. If soil importation is planned, a sample of the soil import should be evaluated by this office prior to importing, in order to assure compatibility with the onsite site soils and the recommendations presented in this report. Import soils for a fill cap should be low expansive (E.I. less than 50). The use of subdrains atthe bottom of the fill cap may be necessary, and subsequently recommended based on compatibility with onsite soils and proximity and/or suitability of an outlet. · Transitions/Overexcavation Cut portions of cut/fill transition pads should be overexcavated a minimum 3 feet below pad grade. Areas with planned fills less than 3 feet should be overexcavated in order to provide a minimum fill thickness of 3 feet, on a preliminary basis. Where the ratio of maximum to minimum fill thickness below a given structure exceeds 3: 1, overexcavation should be completed to reduce this ratio to 3: 1 , or less. Temporary Construction Slopes Proposed site development consists of excavation for garage/basement sub-floors. Temporary cuts for wall construction should be constructed at a gradient or 1 : 1 or flatter for slopes exposing stream terrace deposit materials to a maximum height of 15 feet, per Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128~A-SC December 30, 2003 Page 12 CAL-OSHA for Type B soils. Construction materials and/or stockpiled soil should not be stored within 5 feet of the top of any temporary slope. Temporary/permanent provisions should be made to direct any potential runoff away from the top of temporary slopes. Shoring will likely be required, due to the locally friable conditions of the stream terrace deposits to a depth of approximately 9 feet. Preliminary Shoring Recommendations General Should insufficient space for constructing portions of the proposed residence be encountered, shoring may be required. Shoring should consist of cantilever steel soldier beams placed at a maximum of 6-foot on centers, with a minimum embedment below the bottom of the cut, equivalent to half the height of the cut. The ultimate embedment depth should be provided by the project structural engineer and/or shoring designer, based on the geotechnical parameters provided herein. Wood lagging should be installed as the cut progresses to its ultimate configuration. Lateral Pressures For design on cantilevered shoring, a triangular distribution of lateral earth pressure may be used. It may be assumed that the retained soils with a level surface behind the shoring will exert a lateral ·pressure equal to that developed by a fluid with a density of 40 pcf. Retained soils with a 2: 1 back slope ratio will exert a lateral pressure equal to a fluid with a density of 60 pcf. If street traffic is located within 1 O feet of shorings, the upper 1 O feet of shoting adjacent to the traffic should be designed to resist a uniform lateral pressure of 100 pounds per square foot (psf), which is a result of an assumed 300 psf surcharge behind the shoring due to normal street traffic. Design of Soldier Piles For the design of soldier piles spaced at least two diameters on centers, the allowable lateral bearing value (passive value) of the soils below the level of excavation may be assumed to be 500 psf per foot of depth, upto a maximum of5,000 psf. To develop the full lateral value, provisions should ·be taken to assure firm contact between the soldier piles and the undisturbed soils. The soldier piles below the excavated levels may be used to resist downward loads, if any. The downward frictional resistance between the soldier piles and the soils below the excavated level may be taken as equal to 300 psf. Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 Page 13 I Lagging Continuous wood lagging will be required between the soldier piles. The soldier piles should be designed for the full anticipated lateral pressure. However, the pressure on the lagging will be less due to arching in the soils. We recommend that the lagging be designed for the recommended earth pressure, but limited to a maximum value of 500 psf. Internal Bracing Rakers may be required to internally brace the soldier piles. The raker bracing could be supported laterally by temporary concrete footings (deadmen) or by the permanent interior footings. For design of temporary footings, or deadmen, poured with the bearing surface normal to rakers inclined at 45 degrees, a bearing value of 2,500 psf may be used, provided the shallowest point of the footing is at least 1 foot below the lowest adjacent grade. Deflection It is difficult to accurately predict the amount of deflection of a shored profile. It should be realized, however, that some deflection will occur. We anticipate that this deflection would be on the order of 0.5 inch at the top of the planned 10-to 12-foot shoring. If greater deflection occurs during construction, additional bracing may be necessary to minimize deflection. If desired to reduce the deflection of the shoring, a greater active pressure leading to a more stiffer section could be used. Monitoring Some means of monitoring the performance of the shoring system is recommended. The monitoring should consist of periodic surveying of the lateral and vertical locations of the tops of all the soldier piles and the lateral movement along the entire lengths of selected soldier piles. We suggest that photographs of the adjacent improvements be made prior to excavation. CONVENTIONAL FOUNDATION RECOMMENDATIONS Based on our observations and preliminary test results, onsite soils appear to vary from very low to highly expansive in nature. Preliminary recommendations for foundation construction are presented below. The specific criteria to use for each lot or building pad should be based on evaluation and expansion testing performed after grading is complete. Design 1 . An allowable soil bearing pressure of 1 ,500 psf may be used for the design of continuous footings with a minimum width of 12 inches and depth of 12 inches and for design of isolated pad footings 24 inches square and 18 inches deep founded Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 Page 14 entirely into compacted fill or competent formational material and connected by grade beam or tie beam in at least one direction. This value may be increased by 20 percent for each additional 12 inches in depth to a maximum value of 2,500 psf. 2. An allowable coefficient offriction between concrete and compacted fill or bedrock of 0.35 may be used with the deadload forces. 3. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. 4. Passive earth pressure may be computed as _an equivalent fluid having a density of 250 pounds per cubic foot (pcf) with a maximum earth pressure of 2,500 psf. 5. All footings should maintain a minimum 7-foot horizontal distance between the base · of the footing and any adjacent descending slope, and minimally comply with the guidelines depicted on Figure No. 18-1-1. of the UBC (current edition). Slope Setback Considerations for Footings Footings should maintain a horizontal distance or setback between any adjacent slope face and the bottom out edge of the footing. The horizontal distance may be calculated by using h/3, where h is the height of the slope. The horizontal setback should not be less than 7 feet, nor need not be greater than 40 feet (per UBC code). The setback may be maintained by simply deepening the footings. Flatwork and utilities within a zone of h/3 from the top of slope may be subject to lateral distortion. Footings, flatwork, and utility setbacks should be constructed in accordance with distances indicated in this section and/or the approved plans. Foundation Settlement Foundations systems should be designed to accommodate a worst case differential settlement of 1 inch in a 40-foot span. Construction -. Conventional Foundations The following recommendations may be applied to construction of conventional foundations for typical orie-, two-, and three-story residential structures. The following are preliminary recommendations only. They are to be applied to lots with fill variations of less than 3:1 (buried topography, horizontal to vertical), and total fill thicknesses within the lot of 20 feet or less. If the fill variation or total fill thickness within the lot exceeds these amounts, or soils are highly expansive, then the post-tension foundation recommendations should be followed. Final sampling and testing of the soils at finish grade is recommended prior to foundation construction. Minimum slab thickness should be 5 inches. Recommendations ·for steel reinforcement should be considered minimal and are not meant to supersede the recommendations of the structural engineer or civil engineer Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 Page 15 performing structural design on this project. More onerous foundation design may be governed by UBC criteria, and may necessitate the use of post-tension foundations. Very Low to Low Expansive Soils (E.I. 0-50) 1 . Exterior and interior footings should be founded at a minimum depth of 12 inches for one-story floor loads, 18 inches for two-story floor loads, and 24 inches for three-story floor loads, below the lowest adjacent ground surface. Isolated column and panel pads or wall footings should be founded at a minimum depth of 18 inches, excluding the landscape or weathered zone (top 6 inches). All footings should be reinforced with two No. 4 reinforcing bars, one placed near the top and one placed near the bottom of the footing. Footing widths should be as indicated in the UBC (ICBO, 1997). 2. A grade beam, reinforced as above, and at least 12 inches wide and 12 inches deep (one square foot in cross section) should be provided across large (e.g., garage, double door-ways) entrances. The base of the grade beam should be at the same elevation as the bottom of adjoining footings. 3. Residential concrete slabs, where moisture condensation is undesirable, should be underlain with a vapor barrier consisting of a minimum of 1 O mil polyvinyl chloride or equivalent membrane (due to the blocky nature of capping soils) with all laps sealed. This membrane should be covered above and below with a minimum of 2 inches of sand (total 4 inches of sand, SE >30) to aid in uniform curing of the concrete, and to protect the membrane from puncture. 4. Residential concrete slabs should be a minimum of 5 inches thick, and reinforced No. 3 bars placed at 18 inches on center in both directions. All slab reinforcement should be supported on chairs to ensure placement near the vertical midpoint of the concrete. "Hooking" the bars or other reinforcement is not considered an acceptable method of positioning the reinforcement. 5. Residential garage slabs should be a minimum of 5 inches thick and should be poured separately from the residence footings and quartered with expansion joints or saw cuts. A positive separation from the footings should be maintained with expansion joint material to permit relative movement. 6. Specific presaturation is not required, however, GSI recommends thatthe moisture content of the subgrade soils should be equal to or greater than optimum moisture to a depth of 12 inches below grade in the slab areas. Prior to placing visqueen or reinforcement, soil moisture should be verified by this office within 72 hours of pouring slabs. Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\41.28a.pge W.O. 4128-A-SC December 30, 2003 Page 16 Medium Expansive Soils {E.I. 51-90) 1. Exterior and interior footings should be founded at a minimum depth of 18 inches below the lowest adjacent ground surface for one-or two-story floor loads, and a minimum depth of 24 inches for three-story floor loads. All footings should be reinforced with four No. 4 reinforcing bars, two placed near the top and two placed near the bottom of the footing. Exterior post supports should be founded at a depth of 24 inches below adjacent grade and tied to the main foundation in two directions. 2. A grade beam, reinforced as above, and at least 12 inches wide and 18 inches deep (1 square foot in cross section) should be provided across large (e.g., garage, double door-ways) entrances. The base of the grade beam should be at the same elevation as the bottoni of adjoining footings. 3. Residential concrete slabs, where moisture condensation is undesirable, should be underlain with a vapor barrier consisting .of a minimum of 1 O mil polyvinyl chloride or equivalent membrane (due to the blocky nature of capable soils), with all laps sealed. This membrane should be covered above and below with a minimum of 2 inches of sand (total of 4 inches of sand, SE 30) to aid in uniform curing of the concrete and to protect the membrane from puncture. 4. Residential concrete slabs should be a minimum of 5 inches thick, and be reinforced with No. 3 bars 18 inches on center both ways. All slab reinforcement should.be supported to ensure placement near the vertical midpoint of the concrete. 11Hooking11 the rebar or equivalent reinforcement is not considered an acceptable method of positioning the reinforcement. 5. Residential garage slabs should be a minimum of 5 inches thick and should be poured separately from the residence footings and quartered with expansion joints · or saw cuts. A positive separation from the footings should be maintained with expansion joint material to permit relative movement. 6. Presaturation is recommended for these soil conditions. The moisture content of the subgrade soils should be greater than 120 percent of optimum moisture content to a depth of 18 inches below grade in the slab areas. Prior to placing visqueen or reinforcement, soil presaturation should be verified by this office within 72 hours of pouring slabs. PRELIMINARY POST-TENSIONED SLAB FOUNDATION SYSTEMS Since development plans (i.e., building locations, building types, etc.) for the site are not available atthis time, specific foundation design and construction details would be provided as plans become available. Based on the expansion potential and potential differential settlement, post-tensioned slab foundations may be utilized. Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 Page 17 General The information and recommendations presented in this section are not meant to supersede design by a registered structural engineer or civil engineer familiar with post-tensioned slab design or corrosion engineering consultant. Upon request, GSI could provide additional data/consultation regarding soil parameters as related to post-tensioned slab design during grading. The post-tensioned slabs should be designed in accordance with the Post-Tensioning Institute {PTI) Method. Alternatives to the PTI method may be used if equivalent systems can be proposed which accommodate the angular distortions, expansion potential and settlement noted for this site. Recommendations for utilizing post-tensioned slabs on the site is based on our limited subsurface investigation on the site. The recommendations presented below should be followed in addition to tho~e contained in the previous sections, as appropriate. The information and recommendations presented below in this section are not meant to supercede design by a registered structural .engineer or civil engineer familiar with post-tensioned slab design. Post-tensioned slabs should be designed using sound engineering practice and be in accordance with local and/or national code requirements. Upon request, GSI can provide additional data/consultation regarding soil parameters as related to post-tensioned slab design. From a soil expansion/shrinkage standpoint, a common contributing factor to distress of structures using post-tensioned slabs is fluctuation of moisture in soils underlying the perimeter of the slab, compared to the center, causing a 11dishing11 or "arching" of the slabs. To mitigate this possibility, a combination of soil presaturation and construction of a perimeter cut-off wall should be employed. Perimeter cut-off walls should be a 18 inches deep for medium ahd/or high expansive soils. The cut-off walls may be integrated into the slab design or independent of the slab and should be a minimum of 6 inches thick. The vapor barrier should be covered with a 2-inch layer of sand to aid in uniform curing of the concrete; and it should be lapped adequately to provide a continuous water-proof barrier under the entire slab, with an additional 2 inches of sand placed on grade (4 inches total). Specific soil presaturation is not required; however, the moisture content of the subgrade soils should be equal to, or greater than, the soils' optimum moisture content to a depth of 18 inches below grade, for medium expansive soils, or 24 inches for highly expansive soils. Post-Tensioning Institute Method Post-tensioned slabs should have sufficient stiffness to resist excessive bending due to non-uniform swell and shrinkage of subgrade soils. The differential movement can occur at the corner, edge, or center of slab. The potential for differential uplift can be evaluated using the 1997 UBC Section 1816, based on design specifications of the PTI. The following table presents suggested minimum coefficients to be used in the PTI design method. Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 Page 18 Thornthwaite Moisture Index -20 inches/year Correction Factor for Irrigation 20 inches/year Depth to Constant Soil Suction 7feet Constant Soil Suction (pt) ·, 3.6 Modulus of Subgrade Reaction (pci) 75 Moisture Velocity 0.7 inch/month The coefficients are considered minimums and may not be adequate to represent worst case conditions such as adverse drainage and/or improper landscaping and maintenance. The above parameters are applicable provided structures have positive drainage that is maintained away from structures. Therefore, it is important that information regarding drainage, site maintenance, settlements, and effects of expansive soils be passed on to future owners. · Based on the above parameters, the following values were obtained from figures or tables of the UBC Section 1816 (ICBO, 1997). The values may not be appropriate to account for possible differential settlement of the slab due to other factors. If a stiffer slab is desired, higher values of ym may be warranted. em center lift 5.0 feet 5.0 feet 5.5 feet 5.5 feet 5.5 feet em edge lift 2.5 feet 3.5 feet 4.0 feet 4.5 feet 4.5 feet Y m center lift 1.0 inch 1.7 inches 2.7 inches 3.5 inches · 4.5 inches Ym edge lift 0.3 inch 0.75 inch 0.75 inch 1.2 inches 1.6 inches Deepened footings/edges around the slab perimeter must be used to minimize non-uniform surface moisture migration (from an outside source) beneath the slab. An edge depth of · 12 inches should be considered a minimum for very low to low, medium, or high to very high expansive soils, respectively. The bottom of the deepened footing/edge should be designed to resist tension, using cable or reinforcement per the structural engineer. Other applicable recommendations presented under conventional foundation and the California Foundation Slab Method should be adhered to during the design and construction phase of the project. Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 · Page 19 Should open bottom planters be planned directly adjacent to the foundation system, the values in the above tables would need to be reviewed and/or modified to reflect more highly variable moisture fluctuations along the edges of the foundations. UTILITIES Utilities should be enclosed within a closed utilidor (vault)_ or designed with flexible connections to accommodate differential settlement and expansive soil conditions. Due to the potential for differential settlement, ;:i.ir conditioning (NC) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lin·es. NC waste waterlines should be drained to a suitable outlet. WALL DESIGN PARAMETERS CONSIDERING EXPANSIVE SOILS Conventional Retaining Walls The design parameters provided below assume that either very low expansive soils (Class 2 permeable filter material or Class 3 aggregate base) or native materials are used to backfill any retaining walls. The type of backfill (i.e., select or native), should be specified by the wall designer, and clearly shown on the plans. Building walls, below grade, should be water-proofed or damp-proofed, depending on the degree of moisture protection desired. The foundation system for the proposed retaining walls should be designed in accordance with the recommendations presented in this and preceding sections of this report, as appropriate. Footings should be embedded a minimum of 18 inches below adjacent grade (excluding landscape layer, 6 inches) and should be 24 inches in width. There should be no increase in bearing for footing width. Recommendations for specialty walls (i.e;, crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site specific conditions. Restrained Walls Any retaining walls that will be restrained prior to placing and compacting backfill material or that have re-entrant or male corners, should be designed for an at-rest equivalent fluid pressure (EFP) of 65 pounds per cubic foot (pcf), plus any applicable surcharge loading. For areas of male or re-entrant comers, the restrained wall design should extend a minimum distance of twice the height of the wall (2H) laterally from the corner. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 1 o feet high. Design parameters for walls less than 3 feet in height may be superseded by City and/or County standard design. Active earth pressure may be used for retaining wall Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December30,2003 Page20 design, provided the top of the wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. These do not include other superimposed loading conditions due to traffic, structures, seismic events or adverse geologic conditions. When wall configurations are finalized, the appropriate loading condition_s for superimposed loads can be provided upon request. · Level* 2 to 1 38 55 * Level backfill behind a retai_ning wall· is defined as compacted earth materials, properly drained, without a slope for a distance of 2H_behind the wall. Retaining Wall Backfill and Drainage Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabric and outlets. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Details 1, 2, and 3, present the back drainage options discussed below. Backdrains should consist of a 4-inch diameter perforated PVC or ABS pipe encased in either Class 2 permeable filter material or ½-inch to ¾-inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent). For low expansive backfill, the filter material should extend a minimum of 1 horizontal foot behind the base of the walls and upward at least 1 foot. For native backfill that has up to medium expansion potential, continuous Class 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, and it should be constructed in accordance with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited access and confined areas, (panel) drainage behind the wall may be constructed in accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an expansion index (E.I.) potential of greater than 90 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should conform with Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no greater than + 100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes in walls higher than 2 feet should not be considered. The surface of the backfill should be sealed by pavement or the top 18 inches compacted with native soil (E.I. >90). Proper Mr. Ram Setya · Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge _w.o. 4128-A-SC December 30, 2003 Page 21 Provide surfo.ce dra.lna.ge ±12· (D \Jo. ter proofing MeMbro.ne (optiono.l) @ \Jeephole Finished surfo.ce DETAIL N , T , S , Na. tlve Ba.ckf Ill Slope or Level No. tlve Ba.ck fill (D \J ATER PROOFING MEMBRANE (optlono.D1 Llquiol boot or a.pproveol equlva.lent, @ ROCK1 3/ 4 to 1-1/21 (Inches) rock, @ FILTER F ABRIC1 Miro.fl 140N or o.pprovecl equlva.lent pla.ce fa.bric flo.p behind core. @) PIPE1 41 (Inches) ollo.Meter perf oro. teal PVC, schedule 40 or npproveol o.l terno. tlve with MlnlMUl"I of 1¼ gro.ollent to proper outlet point, @ \./EEPHDLE1 MlnlMUM 2• (Inches) olla.Meter plo.cecl o.t 20' (feet) on centers a.long the wo.ll, a.no! 31 (Inches) o.bove finished surfo.ce, • . TYPICAL RETAINING WALL BACKFILL AND DRAINAGE DETAIL DETAIL 1 Geotechnical • Geologic • Environmental DETAIL N , T . S Provide surf o.ce dro.lno.ge Na. tlve Bo.ckflll or Level CD 'via. ter proofing MeMbra.ne (optlona.D) @ \,/eephole Finished surfe1ce Na. tlve Bo.ckflll @Dra.in @Filter fa.bric {j)Plpe CD \,/ATER PROOFING MEMBRANE (optlona.l)1 Liquid boot or a.pproveci equlva.lent. @ DRAIN, Mlro.olro.ln 6000 or J-dro.ln 200 or equlvo.lent for non-wa. terproof eel wo.lls, Mlra.cira.ln 6200 or J-elra.ln 200 or equlva.lent for wa. ter proof eel wo.lls, fla. ter @ FILTER F ABRIC1 . Mira. fl 140N or a.pprovecl equlvo.lent pla.ce fa.bric flo.p behind core. @ PIPE, 4' (Inches) clla.Meter perf ora. teal PVC, schedule -40 or a.pproved a.l terna. tlve with MlnlMUM of 11/. gra.cllent to proper outlet point. @ \./EEPHDLE• . MlnlMUM 2' (Inches) cllo.rieter pla.cecl n t 20' <feet) on centers a.long the wa.ll, a.ncl 3' (Inches) a.bove flnlshecl surf a.ce, RETAINING WALL BACKFILL AND S.UBDRAIN DETAIL · GEOTEXTILE DRAIN DETAIL 2 Geotechnical • Geologic • Environmental DETAIL N . T . S . Provide surfa.ce dra.lna.ge H ±12' ® \.Jeephole Finished surfa.ce . . @°Filter· · fa.bric 4 Rock __,_ Heel width (D \.J ATER PROOFING MEMBRANE (opt lo no.Di Liquid boot or o.pprovecl equlvo.lent, @ CLEAN SAND BACKFILL1 Must ho. ve so.no! equlva.lent va.lue of 30 or greo. ter J ca.n loe clenslfleol by wa. ter Jetting. @ FILTER F ABRIC1 · Mira.fl 140N or a.pproved equlvo.lent, @ R □CK1 1 cubic foot per llnea.r feet of pipe of 3/4 to 1-1/2' (Inches) rock @ PIPE1 . 4' <Inches) clla.Meter perfora. ted PVC, schedule 40 or a.pproved a.lterno.tlve with MlnlMUM of 1½ gra.dlent. to proper outlet point, @ v/EEPH□LE• MlnlMUM 2' <Inches) die.Meter pla.cecl a.t 20' (feet) on centers a.long the wo.ll, a.ncl 3' (Inches) a.bove finished surf a.ce, D RETAINING WALL AND SUBDRAIN DETAIL CLEAN SAND BACKFILL DETAIL 3 Geotechnical O Geologic • Environmental surface drainage should also be provided. For additional mitigation, consideration should be given to applying a water-proof membrane to the back of all retaining structures. The • use of a waterstop should be considered for all concrete and masonry joints. · Wall/Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from cut to fill, the civil designer may specify either: a) A minimum of a 2-foot overexcavation and recompaction of cut materials for a distance of 2H, from the point of transition. b) Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints or crack control joints) such that a angular distortion of 1 /360 for a distance of 2H on either side of the transition may be accommodated. Expansion joints should be sealed with a flexible, non-shrink grout. · c) Embed the footings entirely into native formational material (i.e., deepened footings). If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation 11a11 (above) and until such transition is between 45 and 90 degrees to the wall alignment. TOP-OF~SLOPE WALLS/FENCES/IMPROVEMENTS AND EXPANSIVE SOILS Expansive Soils and Slope Creep Soils at the site are likely to be expansive and therefore, become desiccated when allowed to dry. Such soils are susceptible to surficial slope creep, especially with seasonal changes in moisture content. Typically in southern California, during the hot and dry summer period, these soils become desiccated and shrink, thereby developing surface cracks. The extent and -depth of these shrinkage cracks depend on many factors such as the nature and expansivity of the soils, temperature and humidity, and extraction of moisture from surface soils by plants and roots. When seasonal rains occur, water percolates into the cracks and fissures, causing slope surfaces to expand, with a corresponding loss in soil density and shear strength near the slope surface. With the passage of time and several moisture cycles, the outer 3 to 5 feet of slope materials experience a very slow, but progressive, outward and downward movement, known as slope creep. For slope heights greater than 1 0 feet, this creep related soil movement will typically impact all rear yard flatwork and other secondary improvements that are located within about 15 feet from the top of slopes, such as swimming pools, concrete flatwork, etc., and in particular top of slope fences/walls. This influence is normally in the form of detrimental settlement, and tilting of the proposed improvements. The dessication/swelling and creep discussed above continues over the Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 . Page 25 life of the improvements, and generally becomes progressively worse. Accordingly, the developer should provide this information to any homeowners and homeowners association. Top of Slope Walls/Fences Due to the potential for slope creep for slopes higher than about 1 o feet, some settlement and tilting of the walls/fence with the corresponding distresses, should be expected. To mitigate the tilting of top of slope walls/fences, we recommend that the walls/fences be constructed on deepened footings, or a combination of grade beam and caisson foundations. The grade beam should be at a minimum of 12 inches by 12 inches in cross section, supported by drilled caissons, 12 inches minimum in diameter, placed at a maximum spacing of 6 feet on center, and with a minimum embedment length of 7 feet below the bottom of the grade beam. The strength of the concrete and grout should be evaluated by the structural engineer of record. The proper ASTM tests for the concrete and mortar should be provided along with the slump quantities. The concrete used should be appropriate to mitigate sulfate corrosion, as warranted. The design of the grade beam and caissons should be in accordance with the recommendations of the project structural engineer, and include the utilization of the following geotechnical parameters: Creep Zone: Creep load: Point of Fixity: Passive Resistance: Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge 5-foot vertical zone below the slope face and projected upward parallel to the slope face. The creep load projected on the area of the grade beam should be taken as an equivalent fluid approach, having a density of 60 pcf. For the caisson, it should be taken as a uniform 900 pounds per linear foot of caisson's depth, located above the creep zone. Located a distance of 1.5 times the caisson's diameter, below the creep zone. Passive earth pressure of 300 psf per foot of depth per foot of caisson diameter, to a maximum value of 4,500 psf may be used to determine caisson depth and spacing, provided that they meet or exceed the minimum requirements stated above. To determine the total lateral resistance, the contribution of the creep prone zone above the point of fixity, to passive resistance, should be disregarded. W.O. 4128-A-SC December 30, 2003 Page 26 Allowable Axial Capacity: Shaft capacity : Tip capacity: 350 psf applied below the point of fixity over the surface area of the shaft. 4,500 psf. EXPANSIVE SOILS. DRIVEWAY. FLATWORK. AND OTHER IMPROVEMENTS The soil materials on site are likely to be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to flatwork and other improvements. The resulting potential for distress to improvements may be reduced, but not totally eliminated. To that end, it is recommended· that the developer should notify any homeowners or homeowners association of this long-term potential for distress. To reduce the likelihood of distress, the following recommendations are presented for all exterior flatwork: 1. The subgrade area for concrete slabs should be compacted to achieve a minimum 90 percentrelative compaction, and then be presoaked to 2 to 3 percentage points above (or 125 percent of) the soils' optimum moisture content, to a depth of 18 inches below subgrade elevation. The moisture content of the subgrade should be verified within 72 hours·prior to pouring concrete. 2. Concrete slabs should be cast over a relatively non-yielding surface, consisting of a 4-inch layer of crushed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete. -The layer should wet-down completely prior to - pouring concrete, to minimize loss of concrete moisture to the surrounding earth materials. 3. Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and approaches should additionally have a thickened edge (12 inches) adjacent to all landscape areas, to help impede infiltration of landscape water under the slab. 4. The use of transverse and longitudinal control joints are recommended to help control slab cracking due to concrete shrinkage or expansion. Two ways to mitigate such cracking are: a) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and, b) provide an adequate amount of control and/or expansion joints to accommodate anticipated concrete shrinkage and expansion. In order to reduce the potential for unsightly cracks, slabs should be reinforced at mid-height with a minimum of No. 3 bars placed at 18 inches on center, in each direction. The exterior slabs should be scored or saw cut,½ to 3/s inches deep, often enough so that no section is greater than 1 O feet by 1 O feet. For sidewalks or narrow Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a;pge W.O. 4128-A-SC December 30, 2003 Page 27 slabs, control joints should be provided at intervals of every 6 feet. The slabs should be separated from the foundations and sidewalks with expansion joint filler material. 5. No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Concrete compression strength should be a minimum of 2,500 psi. 6. Driveways, sidewalks, and patio slabs adjacent to the house should be separated from the house with thick expansion joint filler material. In areas directly adjacent to a continuous source of moisture (i.e., irrigation, planters, etc.), all joints should be additionally sealed with flexible mastic. 7. Planters and walls should not be tied to the house. 8. Overhang structures should be supported on the slabs, or structurally designed with continuous footings tied in at least two directions. 9. Any masonry landscape walls that are to be constructed throughout the property should be grouted and articulated in segments no more than 20 feet long. These segments should be keyed or doweled together. 10. Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. 11. Positive site drainage should be maintained at all times. Finish grade on the lots should provide a minimum of 1 to 2 percent fall to the street, as indicated herein. It should be kept iri mind that drainage reversals could occur, including post- construction settlement, if relatively flat yard drainage gradients are not periodically maintained by the homeowner or homeowners association. 12. Due to expansive soils, air conditioning (NC) units should be supported by slabs that are incorporated into the building foundation or constructed.on a rigid slab with flexible couplings for plumbing and.electrical lines. A/C waste water lines should be drained to a suitable non-erosive outlet. 13. Shrinkage cracks could become excessive if proper finishing and curing practices are not followed. Finishing and curing practices should be performed per the Portland Cement Association Guidelines. Mix design should incorporate rate of curing for climate and time of year, sulfate content of soils, corrosion potential of soils, and fertilizers used on site. Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 Page 28 DEVELOPMENT CRITERIA Slope Deformation Compacted fill slopes designed using customary factors of safety for gross or surficial stability and constructed in general accordance with the design specifications should be expected to undergo some differential vertical heave or settlement in combination with differential lateral movement in the out-of-slope direction, after grading. This post-construction movement occurs in two forms: slope creep, and lateral fill extension (LFE). Slope creep is caused by alternate wetting and drying of the fill soils which results in slow downslope movement. This type of movement is expected to occur throughout the life of the slope, and is anticipated to potentially affect improvements or structures (i.e., separations and/or cracking), placed near the top-of-slope, up to a maximum distance of approximately 15 feet from the top-of-slope, depending on the slope height. This movement generally results in rotation and differential settlement of improvements located within the creep zone. LFE occurs due to deep wetting from irrigation and rainfall on slopes comprised of expansive material$. Althoug_h some movement should be expected, long-term movement from this source may be minimized, but not eliminated, by placing the fill throughout the slope region, wet of the fill's optimum moisture content. It is generally not practical to attempt to eliminate the effects of either slope creep or LFE. Suitable mitigative measures to reduce the potential of lateral deformation typically include: setback of improvements from the slope faces (per the UBC and/or California Building Code), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. All of these measures are recommended for design of structures and improvements. The ramifications of the above conditions, and recommendations for mitigation, should be provided to each homeowner and/or any homeowners association. Slope Maintenance and Planting Water has been shown to weaken the inherent strength of all earth materials. Slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Over-watering should be avoided as it can adversely affect site improvements, and cause perched groundwater conditions. Graded slopes constructed utilizirig onsite materials would be erosive. Eroded debris may be minimized and surficial slope stability enhanced by establishing and maintaining a suitable vegetation cover soon after construction. Compaction to the face offill slopes would tend to minimize short-term erosion until vegetation is established. Plants selected for landscaping should be light weight, deep rooted types that require little water and are capable of surviving the prevailing climate. Jute-type matting or other fibrous covers may aid in allowing the establishment of a sparse plant cover. Utilizing plants other than those recommended above will increase the potential for perched water, staining, mold, etc., to develop. A rodent control program to prevent burrowing should be implemented. Irrigation Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 Page 29 of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to each homeowner. Over-steepening of slopes should be avoided during building construction activities and landscaping. Drainage Adequate lot surface drainage is a very important factor iri reducing the likelihood of adverse performance offoundations,·hardscape, and slopes. Surface drainage should be sufficient to prevent ponding of water anywhere on a lot, and especially near structures and tops of slopes. Lot surface drainage should be carefully taken into consideration during fine grading, landscaping, and building construction. Therefore, care should be taken thatfuture landscaping or construction activities do not create adverse drainage conditions. Positive site drainage within lots and common areas should be provided and maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should be directed away from foundations and not allowed to pond and/or seep into the ground. In general, the area within 5 feet around a structure should slope away from the structure. We recommend that unpaved lawn and landscape areas have a minimum gradient of one percent sloping away from structures, and whenever possible, should be above adjacent paved areas. Consideration should be given to avoiding construction of planters adjacent to structures (buildings, pools, spas, etc.). Pad drainage should be directed toward the street or other approved area(s). Although not a geotechnical requirement, roof gutters, down spouts, or other appropriate means may be utilized to control roof drainage. Down spouts, or drainage devices should outlet a minimum of 5 feet from structures or into a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy rainfall, and should be anticipated. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon request. Erosion Control Cut and fill slopes will be subject to surficial erosion during and after grading. Onsite earth materials have a moderate to high erosion potential. Consideration should be given to providing hay bales and silt fences for the temporary control of surface water, from a geotechnical viewpoint. Landscape Maintenance Only the amount of irrigation necessary to sustain plant life should be provided. Over-watering the landscape areas will adversely affect proposed site improvements. We would recommend that any proposed open-bottom planters adjacentto proposed structures be eliminated for a minimum distance of 1 O feet. As an alternative, closed-bottom type planters could be utilized. An outlet placed in the bottom of the planter, could be installed to direct drainage away from structures or any exterior concrete flatwork. If planters are constructed adjacent to structures, the sides and bottom of the planter should be provided Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 Page 30 with a moisture barrier to prevent penetration of irrigation water into the subgrade. Provisions should be made to drain the excess irrigation water from the planters without saturating the subgrade below or adjacent to the planters. Graded slope areas should be planted with drought resistant vegetation. Consideration should be given to the type of vegetation chosen and their potential effect upon surface improvements (i.e., some trees will have an effect on concrete flatwork with their extensive root systems). From a geotechnical standpoint leaching is not recommended for establishing landscaping. If the surface soils are processed for the purpose of adding amendments, they should be recompacted to 90 percent minimum relative compaction. Gutters and Downspouts As previously discussed in the drainage section, the installation of gutters and downspouts should be considered to collect roof water that may otherwise infiltrate the soils adjacent to the structures. If utilized, the downspouts should be drained into PVC collector pipes or non-erosive devices that will carry the water away from the house. Downspouts and gutters are not a requirement; however, from a geotechnical viewpoint, provided that positive drainage is incorporated into project design (as discussed previously). Subsurface and Surface Water Subsurface and su·rface water are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into final design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities may not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Groundwater conditions may change with the introduction of irrigation, rainfall, or other factors. Site Improvements · Recommendations for exterior concrete flatwork design and construction can be provided upon request. If in the future, any additional improvements (e.g., pools, spas, etc.) are planned for the site, recommendations concerning the geological or geotechnical aspects of design and construction of said improvements could be provided upon request. This office should be notified in advance of any fill placement, grading of the site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench, and retaining wall backfills. Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 · Page 31 Tile Flooring Tile flooring can crack, reflecting cracks in the concrete slab below the tile, although small cracks in a conventional slab may not be significant. Therefore, the designer should consider .addiJional steel reinforcement for concrete slabs-on-grade where tile will be placed. The tile installer should consider installation methods that reduce possible cracking of the tile such as slipsheets. Slipsheets or· a vinyl crack isolation membrane (approved by the Tile Council of America/Ceramic Tile Institute) are recommended between tile and concrete slabs on grade. Additional Grading This office should be notified in advance of any fill placement, supplemental regrading of the site, or trench backfilling after rough grading has been completed. This includes completion of grading in the street and parking areas and utility trench and retaining wall backfills. Footing Trench Excavation All footing excavations should be observed by a representative of this firm subsequent to trenching and prior to concrete form and reinforcement placement. The purpose of the observations is to verify that the excavations are made into the recommended bearing material and to the minimum widths and depths recommended for construction. If loose or compressible materials are exposed within the footing excavation, a deeper footing or removal and recompaction of the subgrade materials would be recommended atthattime. Footing trench spoil and any excess soils generated from utility trench excavations should be compacted to a minimum relative compaction of 90 percent, if not removed from the site. Trenching Considering the nature of the onsite soils, it should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls at the angle of repose (typically 25 to 45 degrees) may be necessary and should be anticipated. All excavations should be observed by one of our representatives and • minimally conform to CAL-OSHA and local safety codes. Utility Trench Backfill 1. All interior utility trench backfill should be brought to at least 2 percent above optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard. As an alternative for shallow (12-inch to 18-inch) under-slab trenches, sand having a sand equivalent value of 30 or greater may be utilized and jetted or flooded into place. Observation, probing and testing should be provided to verify the desired results. Mr. Ram Setya Viejo Castilla, Carlsbad • File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December30,2003 Page 32 2. Exterior trenches adjacent to, and within areas extending below a 1 :1 plane projected from the outside bottom edge of the footing, and all trenches beneath hardscap·e features and in slopes, should be compacted to at least 90 percent of the laboratory standard. Sand backfill, unless excavated from the trench, should not be used in these backfill areas. Compaction testing and observations, along with probing, should be accomplished to verify the desired results. 3. All trench excavations should conform to CAL-OSHA and local safety codes. 4. Utilities crossing grade beams, perimeter beams, or footings should either pass below the footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade beam in accordance with the recommendations of the structural engineer. ·, SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend that observation and/or testing be performed by GSI at each of the following construction stages: • During grading/recertification. • After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. • Prior to pouring any slabs or flatwork, after presoaking/presaturation of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor barriers (i.e., visqueen, etc.). • During retaining wall subcfrain installation, prior to backfill placement. • During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. • During slope construction/repair. • When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. • When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed. Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December30,2003 Page 33 • A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and clear documentation of site work, and/or to comply with code requirements. OTHER DESIGN PROFESSIONALS/CONSULTANTS The design civil engineer, structural engineer, post-tension designer, architect, landscape architect, wall. designer, etc., should review the recommendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plans. PLAN REVIEW Final project plans should be reviewed by this office prior to construction; so that construction is in accordance with th_e conclusions and recommendations of this report. Based on our review, supplemental recommendations and/or further geotechnical studies may be warranted. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty is expressed or implied. Standards of practice are subjectto change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Mr. Ram Setya Viejo Castilla, Carlsbad File:e:wp9\4100\4128a.pge W.O. 4128-A-SC December 30, 2003 Page 34 APPENDIX A REFERENCES GeoSoils, Inc. APPENDIX A REFERENCES Blake, T.F., 2000a, EQFAULT, A computer program for the estimation of peak horizontal acceleration from 3-D fault sources; Windows 95/98 version. __ , 2000b, EQSEARCH, A computer program for the estimation of peak horizontal · acceleration from California historical earthquake catalogs; Updated to June, 2003, Windows 95/98 version. __ , 2000c, FRISKSP, A computer program for the probabilistic estimation of peak acceleration and uniform hazard spectra using 3-D faults as earthquake sources; Windows 95/98 version. Campbell, K.W. and Bozorgnia, Y., 1994, Near-source attenuation of peak horizontal acceleration from worldwide accelerograms recorded from 1957 to 1993; Proceedings, Fifth U.S. National Conference on Earthquake Engineering, volume 111, Earthquake Engineering Research Institute, pp 292-293. International Conference of building officials, 1997, Uniform building code: Whittier, California, vol. 1, 2, and 3. Jennings, C.W., 1994, Fault activity map of California and adjacent areas: California Division of Mines and Geology, map sheet no. 6, scale 1 :750,000. Joyner, W.B., and Boore, D.M., 1982, Estimation of response-spectral values as functions of magnitude, distance and site conditions, in eds., Johnson, J.A., Campbell, K.W., and Blake, T.F., AEG Short Course, Seismic Hazard Analysis, dated June 18, 1994. Kennedy, M.P. and Tan S.S., 1996, Geologic maps of the northwest part of San Diego County, California, Division of Mines and Geology, plate 1, scale 1 :24,000. Petersen, Mark D., Bryant, W.A., and Cramer, C.H., 1996, Interim table of fault parameters used by the California Division of Mines and Geology to compile the probabilistic seismic hazard maps of California. Sadigh, K., Egan, J., and Youngs, R., 1987, Predictive ground motion equations reported in Joyner, W.B., and Boore, D.M., 1988, "Measurement, Characterization, and Prediction of Strong Ground Motion," in Earthquake Engineering and Soil Dynamics 11, Recent Advances in Ground Motion Evaluation, Von Thun, .J.L., ed.: American Society of Civil Engineers Geotechnical Special Publication No. 20, pp. 43-102 . . Sowers and Sowers, 1970, Unified soil classification system (After U. S. Waterways Experiment Station and ASTM 02487-667) in Introductory Soil Mechanics, New York. APPENDIX B TEST PIT LOGS . •test': .. . . . ..... .. . .... . PIT.NO. : TP-1 0-1 1-1½ 1½-10 4128-A-SC Viejo Castilla December15,2003 LOG OF EXPLORATORY TEST PITS SAMPLE!' t/FIELDDRY:: ; GROUP i·•: 1···• :DEPTH< . · .. ;·DENSITY'':·;: •:·:• ·: .: .,,· ..... · ... · .. : ·· />.,_.; . '·.':'<0:·:· .. ···· · •··••• .. :· .·'. · · ·,.,., .... ,.:.,,,., ; " ·::.,·,:·,:, .. I ·· SYMBOL· ·. '(ft)·•··.· · ·.· ... · (%)·,,·., ...... ·, ·., ·· · (pcf)'·" · · .. . _·.. . ... : ,'.·:.:·-.,, ........... :. . -·, ... ::. . ·--::·::·.·:::.::::. . . ·:?:·: ML SC SM Rings@4 Bulk@5 5.5 101.6 ARTIFICIAL FILL (UNDOCUMENTED): SILT, greenish gray, moist, soft. TOPSOIL/COLLUVIUM: CLAVEY SAND, red brown, moist, loose. SWEITZER FORMATION, STREAM TERRACE DEPOSITS: SILTY SAND, red brown, wet, loose to medium dense; fine to coarse grained, scattered cobble layers, rounded cobbles ~3 inches, several thin discontinuous clay layers. Total Depth = 1 0' No Groundwater Encountered Backfilled12-15-2003 PLATE B-1 TP-2 0-2 2-4 @4 @8 l''!i·f!! .. [lt • :~)?:~\ .. LOG OF EXPLORATORY TEST PITS 4128-A-SC Viejo Castilla December 15, 2003 ; 1. •--'-< -. ; ·;: .: ,;·"' ;_~;.-· .. .: :·. ~~uB;t ·I. (SJf ~~Ee .{,jB:~~i :~ ~~1ilil ML CH Bulk@3 CH Bulk@? SM ARTIFICIAL FILL (UNDOCUMENTED): SILT, greenish gray, moist, soft. TOPSOIL/COLLUVIUM: CLAYEY SAND, red, moist, loose. SWEITZER FORMATION. STREAM TERRACE DEPOSITS: CLAY, red brown, moist, very stiff; scattered cobbles and sand. SILTY SAND, red brown, moist, medium dense; scattered cobbles. Total Depth = 9' No Groundwater Encountered ·. Backfilled 4-15-2003 PLATE B-2 TP-3 4128-A-SC Viejo Castilla December 15, 2003 LOG OF EXPLORATORY TEST PITS .. _, ........ . •...• • . <. i i ... :::~At1.11JJLe:'.: ·:: r::..·. -_, . DEPTH< •>GROUP \FDEPTH > ·••• MOISTU ·••1'\;{(ft;)\:. rsvMsoL.>: ::j(:(fr}(:\. :\••<')::(%)}/:: 0-1 ML 1-4 SM .,. .... .··: a:+(pcf}\-i ARTIFICIAL FILL {UNDOCUMENTED): SILT, greenish gray, moist, soft. SWEITZER FORMATION. STREAM TERRACE DEPOSITS: SILTY SAND, red brown, moist, loose to medium dense; abundant cobbles. Total Depth = 41 No Groundwater Encountered Backfilled 4-15-2003 PLATE B-3 TP-4 I-4128-A-SC Viejo Castilla December 15, 2003 LOG OF EXPLORATORY TEST PITS \?t:i: :;=;:: .:·, .. · .. -· :··•·= .• · i.:.§AMPL§.\ ····•····•.· .. ··.·· .. ·.··.·:··:i::'.:1:: [im~·1EL0::0Rxf . DEPTH ····GROUP·'· =··· ··oEPTH=····•··· ·= MOISTURE." '.• ' ·'DENSITY··=•···'''· ,. ·•.:==<ctt.>••::1:: .;: sv.MeoL';i· ·•;::i\;cn~)tii= · .·•••·•f:::-::1•••<%.>·••=·•••:· ·.):•• ·f::/:I::•:;:(Pt?ij'ti:t\U: . 0-1 CL 1-4 CLJSC 5-6 ML TOPSOIL/COLLUVIUM: SANDY CLAY, red brown, moist, soft; scattered cobbles. SWEITZER FORMATION, STREAM TERRACE DEPOSITS: SANDY CLAY, red brown, moist, stiff. SILT, light red brown, moist, stiff. Total Depth = 61 No Groundwater Encountered Backfilled 12-15-2003 PLATE 8-4 APPENDIXC EQFAULT s.... ro CD >- CJ) ..... C CD > w -0 I-CD .c E :J z CD > :;::::; ro :J E E :J (.) EARTHQUAKE·RECURRENCE CURVE Viejo Castilla l--+---+---1---1---1----+-----+----+------.f---+---lii ':' l---+---+----+----+---+---+---1----1---11--+---l[ {f. l---+---+----+--,---+---+---+---l----+--11--+---l:' f,~ t 1 O lE _E _E _E +-E _E _E _E +g _E _E_E +t _E -~§--+~-§ _E _E_t§ _E _E _E +-g _E _E _E +f _E _E _E -+! _E _E _E --l~LE _E _E _E +-E _E _E ---l~lt .1 l--+---+---1---1---1----+-----+----+------.f---+---l1, l--+---+---1---1---1----+-----+----+------.f---+---l!; l---+---+----+----+---+---+---1----1---11--+---l~~ l--+---+---1---1---1----+-----+----+------.f---+-----I~ i 9 " '{, s. ;: l----l---+---=~+---+-----l---l---+---1-----11----1------lt, l---+---+-----="-~--+-----l---l---+---1-----11----1------l' ~ ~-l--+---+----t-~d---+---+--+----+--11--+-----l~ l ......... l----l---+--+---+-~,-l---l---+---1-----11----1------l'· ~t-,....._ ~ c ► ~ r ;: t:" ~ " ' l---+---+----+----+---+---+---1---'-+----+-----i----l~ ;t 0 f---+---+----+----+---+----+---+----+--1---+-----I~ f---+---+----+----+---t----+---+-----iillll----1---+-----I, f---+---+----+----+---+----+---+----+--1---+-----i' ~ ,. j; " f---+---+----+----+---+----+---+----+--1---+-----i'I '· r , . . 001 l§_§_t§_§--,l§_§_,i_§_§_,i~§_§_,l§_§_,i~§_§_,i_§_§---li_§_§---li_§_§_,l§_~~ i---+-----1---1---1----1----+-----+---.--1--+----lL'. f---+---+----+----+---+----+---+----+--1---+-----li r: f---+---+----+----+----1----+---+----+--1---+-----lf l---+---+----+----+---+---+----+----+--l---+-----11~ t: 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 ~ 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 Magnitude (M) W.O. 4128-A-SC Plate C-1 ........... ?f?. ............ >. wf-1 ·- ..a co ..a 0 s... CL Q) (.) c· co . 'O Q) Q) (.) >< UJ PROBABILITY OF EXCEEDANCE CAMP. & BOZ. (1997 Rev.) SR 1 100 90 80 70 60 50 40 30 20 10 I • I I ... I 25 yrs 50 yrs I ■ I I T I 75, rs 100 rs 0.00 0.25 0.50 0. 75 1.00 1.25 1.50 Acceleration (g) W.O. 4128-A-SC Plate C-2 :e 9 ~ ..... I\) 0) I J> I en 0 :!! I» .... (I) 0 I c,:, ...--... (/) !.... >-..._... 1J 0 ·-!.... (]) Cl. C !.... ::J +-' (]) ~ RETURN PERIOD vs. ACCELERATION CAMP. & BOZ. (1997 Rev.) SR 1 ./ / / 1000000 V -,,_ ,, ./ • / 100000 / (' -- / / ,II' / 10000 / --, / / /' 1000 / -, -/ ., ,I' 100 / - I I I I I I I I I I I I I I I I I I I I I ·I I I I 0.00 0.25 0.50 0.75 1.00 1.25 1.50 Acceleration (Q) APPENDIX D GENERAL EARTHWORK AND GRADING GUIDELINES GENERAL EARTHWORK AND GRADING GUIDELINES General These guidelines present general procedures and requirements for earthwork and grading as shown on the approved grading plans, including preparation of areas to filled, placement of fill, installation of subdrains and excavations. The recommendations contained in the geotechnical report are part of the earthwork and grading guidelines and would supercede the provisions contained hereafter in the case of conflict. Evaluations performed by the consultant during the course of grading may result in new recommendations which could supersede these guidelines or the recommendations contained in the geotechnical report. The contractor is responsible for the satisfactory completion of all earthwork in accordance with provisions of the project plans and specifications. The project soil engineer and engineering geologist (geotechnical consultant) or their representatives should provide observation and testing services, and geotechnical consultation during the duration of the project. EARTHWORK OBSERVATIONS AND TESTING Geotechnical Consultant Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer and engineering geologist) should be employed for the purpose of observing earthwork procedures and testing the fills for conformance with the recommendations of the geotechnical report, the approved grading plans, and applicable grading codes and ordinances. The geotechnical consultant should provide testing and observation so that determination may be made that the work is being accomplished as specified. It is the responsibility of the contractor to assist the consultants and keep them apprised of anticipated work schedules and changes, so that they may schedule their personnel accordingly. All clean-outs, prepared ground to receive fill, key excavations, and subdrains should be observed and documented by the project engineering geologist and/or soil engineer prior to placing and fill. It is the contractors's responsibility to notify the engineering geologist and soil engineer when such areas are ready for observation. Laboratory and Field Tests Maximum tjry density tests to determine the degree of compaction should be performed in · accordance with American Standard Testing Materials test method ASTM designation D-1557-78. Random field compaction tests should be performed in accordance.with test method ASTM designation D-1556-82, D-2937 or D-2922 and D-3017, at intervals of approximately 2 feet of fill height or every 100 cubic yards of fill placed. These criteria would vary depending on the soil conditions and the size of the project. The location and frequency of testing would be at the discretion of the geotechnical consultant. . Contractor's Responsibility All clearing, site preparation, and earthwork performed on the project should be conducted by the contractor, with observation by geotechnical consultants and staged approval by the governing agencies, as applicable. It is the contractor's responsibility to prepare the ground surface to receive the fill, to the satisfaction of the soil engineer, and to place, spread, moisture condition, mix and compact the fill in accordance with the recommendations of the soil engineer. The contractor should also remove all major non-earth material considered unsatisfactory by the soil engineer. It is the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the earthwork in accordance with applicable grading guidelines, codes or agency ordinances, and approved grading plans. Sufficient watering apparatus and compaction equipment should be provided by the contractor with due consideration for the fill material, rate of placement, and climatic conditions. If, in the opinion of the geotechnical consultant, unsatisfactory conditions such as questionable weather, excessive oversized rock, or deleterious material, insufficient support equipment, etc., are resulting in a quality of work that is not acceptable, the consultant will inform the contractor, and the contractor is expected to rectify the conditions, and if necessary, stop work until conditions are satisfactory. During construction, the contractor shall properly grade all surfaces to maintain good drainage and prevent' ponding of water. The contractor shall take remedial measures to control surface water and to prevent erosion of graded areas until such time as permanent drainage_ and erosion control measures have been installed. SITE PREPARATION All major vegetation, including brush, trees, thick grasses, organic debris, and other deleterious material should be removed and disposed of off-site. These removals must be concluded prior to placing fill. Existing fill, soil, alluvium, colluvium, or rock materials determined by the soil engineer or engineering geologist as being unsuitable in-place should be removed prior to fill placement. Depending upon the soil conditions, these materials may be reused as compacted fills. Any materials incorporated as part of the compacted fills should be approved by the soil engineer. Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic tanks, wells, pipelines, or other structures not located prior to grading are to be removed or treated in a manner recommended by the soil engineer. Soft, dry, spongy, highly fractured, or otherwise unsuitable ground extending to such a depth that surface processing cannot adequately improve the condition should be overexcavated down to firm ground and approved by the soil engineer before compaction and filling operations continue. Overexcavated and processed soils which have been properly mixed and moisture Mr. Ram Setya File:e:\wp9\4100\4128a.pge Appendix D Page2 conditioned should be re-compacted to the minimum relative compaction as specified in these guidelines. Existing ground which is determined to be satisfactory for support of the fills should be scarified to a minimum depth of 6 inches or as directed by the soil engineer. After the scarified ground is broughtto optimum moisture content or greater and mixed, the materials should be compacted as specified herein.· If the scarified zone is grater that 6 inches in depth, it may be necessary to remove the excess and place the material in lifts restricted to about 6 inches in compacted thickness. Existing ground which is not satisfactory to support compacted fill should be overexcavated as required in the geotechnical report or by the on-site soils engineer and/or engineering geologist. Scarification, disc harrowing, or other acceptable form of mixing should continue until the soils are broken down and free of large lumps or clods, until the working surface is reasonably uniform and free from ruts, hollow, hummocks, or other uneven features which would inhibit compaction as described previously. Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to ve·rtical), the ground should be stepped or benched. The lowest bench, which will act as a key, should be a minim!lm of 15 feet wide and should be at least 2 feet deep into firm material, and approved by the soil engineer and/or engineering geologist. In fill over cut slope conditions, the recommended minimum width of the lowest bench or key is also 15 feet with the key founded on firm material, as designated by the Geotechnical Consultant. As a general rule, unless specifically recommended otherwise by the Soil Engineer, the minimum width of fill keys should be approximately equal to ½ the height of the slope. Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable material. Benching may be used to remove unsuitable materials, although it is understood that the vertical height of the bench may exceed 4 feet. Pre-stripping may be considered for unsuitable materi~ls in excess of 4 feet in thickness. All areas to receive fill, including processed areas, removal areas, and the toe of fill benches should be observed and approved by the soil engineer and/or engineering geologist prior to placement of fill. Fills may then be properly placed and compacted until design grades (elevations) are attained. COMPACTED FILLS Any earth materials imported or excavated on the property may be utilized in the fill provided that each material has been determined to be suitable by the soil engineer. These materials should be free of roots, tree branches, other organic matter or other deleterious materials. All unsuitable materials should be removed from the fill as directed by the soil engineer. Soils of poor gradation, undesirable expansion potential, or substandard strength Mr. Ram Setya File:e:\wp9\4100\4128a.pge Appendix D Page3 characteristics may be designated by the consultant as unsuitable and may require blending with other soils to serve as a satisfactory fill material. Fill materials derived from benching operations should be dispersed throughout the fill area and blended with other bedrock derived material. Benching operations should not result in the benched material being placed only within a single equipment width away from the fill/bedrock contact. Oversized materials defined as rock or other irreducible materials with a maximum dimension greater than 12 inches should not be buried or placed in fills unless the location of materials and disposal methods are specifically approved by. the soil engineer. Oversized material should be taken off-site or placed in accordance with recommendations of the soil engineer in areas designated as suitable for rock disposal. Oversized material should not be placed within 1 O feet vertically of finish grade (elevation) or within 20 feet horizontally of slope faces. To facilitate future trenching, rock should not be placed within the range of foundation ~xcavations, future utilities, or underground construction unless specifically approved by the soil engineer and/or the developers representative. If import material is required for grading, representative samples of the materials to be utilized as compacted fill should be analyzed in the laboratory by the' soil engineer to determine its physical properties. If any material other than that previously tested is encountered during grading, an appropriate analysis of this material should be conducted by the soil engineer as soon as possible. Approved fill material should be placed in areas prepared to receive fill in near horizontal layers that when compacted should not exceed 6 inches in thickness. The soil engineer may approve thick lifts if testing indicates the grading procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each layer should be spread evenly and blended to attain uniformity of material and moisture suitable for compaction. Fill layers at a moisture content less than optimum should be watered and mixed, and wet fill layers should be aerated by scarification or should be blended with drier material: Moisture condition, blending, and mixing of the fill layer should continue until the fill materials have a uniform moisture content at or above optimum moisture. After each layer has been evenly spread, moisture conditioned and mixed, it should be uniformly compacted to a minimum of 90 percent of maximum density as determined by ASTM test designation, D-1557-78, or as otherwise recommended by the soil engineer. Compaction equipment should be adequately sized and should be specifically designed for soil compaction or of proven reliability to efficiently achieve the specified degree of compaction. Mr. Ram Setya File:e:\wp9\4100\4128a.pge Appendix D Page4 Where tests indicate that the density of any layer of fill, or portion thereof, is below the required relative compactkm, or improper moisture is in evidence, the particular layer or portion shall be re-worked until the required density and/or moisture content has been attained. No additional fill shall be placed in an area until the last placed lift of fill has been tested and found to meet the density and moisture requirements, and is approved by the soil engineer. Compaction of slopes should be accomplished by over-building a minimum of 3 feet horizontally, and subsequently trimming back to the design slope configuration. Testing shall be performed as the fill is elevated to evaluate compaction as the fill core is being developed. Special_ efforts may be necessary to attain the specified compaction in the fill slope zone. Final slope shaping should be performed by trimming and removing loose materials with appropriate equipment. A final determination offill slope compaction should be based on observation and/or testing of the finished slope face. Where compacted fill slopes are designed steeper than 2:1 (horizontal to vertical), specific material types, a higher minimum relative compaction, and special grading procedures, may be recommended. If an alternative to over-building and cutting back the compacted fill slopes is selected, then special effort should be made to achieve the required compaction in the outer 1 o feet of each lift of fill by undertaking the following: 1. An extra piece of equipment consisting of a heavy short shanked sheepsfoot should be used to roll (horizontal) parallel to the slopes continuously as fill is placed. The sheepsfoot roller should also be used to roll perpendicular to the slopes, and extend out over the slope to provide adequate compaction to the face of the slope. 2. Loose fill should not be spilled out over the face of the slope as each lift is compacted. Any loose fill spilled over a previously completed slope face should be trimmed off or be subject to re-rolling. 3. Field compaction tests will be made in the outer (horizontal) 2 to 8 feet of the slope at appropriate vertical intervals, subsequent to compaction operations. 4. After completion of the slope, the slope face should be shaped with a small tractor and then re-rolled with a sheepsfoot to achieve compaction to near the slope face. Subsequent to testing to verify compaction, the slopes should be grid-rolled to achieve compaction to the slope face. Final testing should be used to confirm compaction after grid rolling. 5. Where testing indicates less than adequate compaction, the contractor will be responsible to rip, water, mix and re-compact the slope material as necessary to achieve compaction. Additional testing should be performed to verify compaction. Mr. Ram Setya File:e:\wp9\4100\4128a.pge Appendix D Page5 6. Erosion control and drainage devices should be designed by the project civil engineer in compliance with ordinances of the controlling governmental agencies, and/or in accordance with the recommendation of the soil engineer or engineering geologist. SUBDRAIN INSTALLATION Subdrains should be installed in approved ground in accordance with the approximate alignment and details indicated by the geotechnical consultant. Subdrain !~cations or materials should not be changed or modified without approval of the geotechnical consultant. The soil engineer and/or engineering geologist may recommend and direct changes in subdrain line, grade and drain material in the field, pending exposed conditions. The location of constructed subdrains should be recorded by the project civil engineer. EXCAVATIONS Excavations and cut slopes should be examined during grading by the engineering geologist. If directed by the engineering geologist, further excavations or overexcavation and re-filling of cut areas should be performed and/or remedial grading of cut slopes should be performed. When fill over cut slopes are to be graded, unless otherwise approved, the cut portion of the slope should be observed by the engineering geologist prior to placement of materials for construction of the fill portion of the slope. The engineering geologist should observe all cut slopes and should be notified by the contractor when cut slopes are started. If, during the course of grading, unforeseen adverse or potential adverse geologic conditions are encountered, the engineering geologist and soil engineer should investigate, evaluate and make recommendations to treat these problems. The need for cut slope buttressing or stabilizing should be based on in-grading evaluation by the engineering geologist, Whether anticipated or not. Unless otherwise specified in soil and geological reports, no cut slopes should be excavated higher or steeper than that allowed by the ordinances of controlling governmental agencies. Additionally, short-term stability of temporary cut slopes is the contractors responsibility. Erosion control and drainage devices should be designed by the project civil engineer and should be constructed in compliance with the ordinances of the controlling governmental agencies, and/or in accordance with the recommendations of the soil engineer or engineering geologist. Mr. Ram Setya File:e:\wp9\4100\412Ba.pge Appendix D Page6 COMPLETION· Observation, testing and consultation by the geotechnical consultant should be conducted during ~he grading operations in order to state an -opinion that all cut and filled areas are graded in accordance with the approved project specifications. After completion of grading and after the soil engineer and engineering geologist have finished their observations of the work, final reports should be submitted subject to review by the controlling governmental agencies. No further excavation or filling should be undertaken without prior notification of the soil engineer and/or engineering geologist. All finished cut and fill slopes should be protected from erosion and/or be planted in accordance with the project specifications and/or as recommended by a landscape architect. Such protection and/or planning should be undertaken as soon as practical after completion of grading. JOB SAFETY General At GeoSoils, Inc. (GSI) getting the job done safely is of primary concern. The following is the company's safety considerations for use by all empl'oyees on multi-employer construction sites. On ground personnel are at highest risk of injury and possible fatality on grading and construction projects. GSI recognizes that construction activities will vary on each site and that site safety is the prime responsibility of the contractor; however, everyone must be safety conscious and responsible at all times. To achieve our goal of avoiding accidents, cooperation between the client, the-contractor and GSI personnel must be maintained. In an effort to minimize risks associated with geotechnical testing and observation, the following precautions are to be implemented for the safety offield personnel on grading and . construction projects: Safety Meetings: GSI field personnel are directed to attend contractors regularly scheduled and documented safety meetings. Safety Vests: Safety vests are provided for and are to be worn by GSI personnel at all times when they are working in the field. Safety Flags: Two safety flags are provided to GSI field technicians; one is to be affixed to the vehicle when on site, the other is to be placed atop the spoil pile on all test pits. Mr. Ram Setya Appendix D File:e:\wp9\4100\4128a.pge Page 7 Flashing Lights: All vehicles stationary in the grading area shall use rotating or flashing amber beacon, or strobe lights, on the vehicle during all field testing. While operating a vehicle in the grading area, the emergency flasher on the vehicle shall be activated. In the event that the contractor's representative observes any of our personnel not following the above, we request that it be brought to the attention of our office. Test Pits Location, Orientation and Clearance The technician is responsible for selecting test pit locations. A primary concern should be the technicians's safety. Efforts will be made to coordinate locations with the grading contractors authorized representative, and to select locations following or behind the established traffic pattern, preferably outside of current traffic: The contractors authorized representative (dump man, operator, supervisor, grade checker, etc.) should direct excavation of the pit and safety during the test period. Of paramount concern should be the soil technicians safety and obtaining enough tests to represent the fill. Test pits should be excavated so that the spoil pile is placed away form oncoming traffic, whenever possible. The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This necessitates the fill be maintained in a driveable condition. Alternatively, the contractor may wish to park a piece of equipment in front of the test holes, particularly in small fill areas or those with limited access. A zone of non-encroachment should be established for all test pits. No grading equipment should enter this zone during the testing procedure. The zone should extend approximately 50 feet outward from the center of the test pit. This zone is established for safety and to avoid excessive ground vibration which typically decreased test results. When taking slope tests the technician should park the vehicle directly above or below the test location. If this is not possible, a prominent flag should be placed at the top of the slope. The contractor's representative should effectively keep all equipment at a safe operation distance (e.g'.' 50 feet) away from the slope during this testing. The technician is directed to withdraw from the active portion of the fill as soon as possible following testing. The technician's vehicle should be parked at the perimeter of the fill in a highly visible location, well away from the equipment traffic pattern. The contractor should inform our personnel of all changes to haul roads, cut and fill areas or other factors that may affect site access and site safety. In the event that the technicians safety is jeopardized or compromised as a result of the contractors failure to comply with any of the above, the technician is req·uired, by company policy, to immediately withdraw and notify his/her supervisor. The grading contractors Mr. Ram Setya File:e:\wp9\4100\4128a.pge Appendix D Page 8 representative will eventually be contacted in an effort to effect a solution. However, in the interim, no further testing will be performed until the situation is rectified. Any fill place can be considered unacceptable and subject to reprocessing, recompaction or removal. In the event that the soil technician does not comply with the above or other established safety guidelines, we request that the contractor brings this to his/her attention and notify this office. Effective communication and coordination between the contractors representative and the soils technician is strongly encouraged in order to implement the above safety plan. Trench and Vertical Excavation It is the contractor's responsibility to provide safe access into trenches where compaction testing is needed. Our personnel are directectnot to enter any excavation or vertical cut which: 1) is 5 feet or deeper unless shored or laid back; 2) displays any evidence of instability, has any loose rock or other debris which could fall into the trench; or 3) displays any other evidence of any unsafe conditions regardless of depth. All trench excavations or vertical cuts in• excess of 5 feet deep, which any person enters, should be shored or laid back. Trench access should be provided in accordance with CAL- OSHA and/or state and local standards. Our personnel are directed not to enter any trench by being lowered or "riding down" on the equipment. If the contractor fails to provide safe access to trenches for compaction testing, our company policy requires that the soil technician withdraw and notify his/her supervisor. The contractors representative will eventually be contacted in an effort to effect a solution. All backfill not tested due to safety concerns or other reasons could be subject to reprocessing and/or removal. If GSI personnel become aware of anyone working beneath an unsafe trench wall or vertical excavation, we have a legal obligation to put the contractor and owner/developer on notice to immediately correct the situation. If corrective steps are not taken, GSI then has an obligation to notify CAL-OSHA and/or the proper authorities. Mr. Ram Setya File:e:\wp9\4100\4128a.pge GeoSoils, lne .. Appendix D · Page9 FILL OVER NATURAL □ET AIL SIDEHILL FILL COMPACTED FILL TOE OF SLOPE AS SHOWN ON GRADING PLAN NCH/BACKCUT _____, PROVIDE A 1:1 MINIMUM PROJECTION FROM DESIGN TOE OF SLOPE TO TOE OF KEY . "'""t~~,~\.. o~ u~su\"t~Q\$ ~ ~ AS SHOWN ON AS BUILT NATURAL SLOPE TO BE RESTORED WITH -0 r )> cO'-'-\)'l\\)\A, -.i'a: "t0~5Q\\... ---~ lli"''I\WI/\\' II T4' 1\11-\,\U• • _ . ' MINIMUM ,1 .:::: ---f ,,.,.,, .. ,, ··: .... ~ :E: MINIMUM BENCH WIDTH MAY VARY NOTE: 1, WHERE THE NA!URAL SLOPE APPROACHES OR EXCEE·DS THE --------------1 15' MINIMUM KEY WIDTH 2'X 3' MINIMUM KEY DEPTH DESIGN SLOPE RATIO. SPECIAL RECOMMENDATIONS WOULD BE PROVIDED BY THE SOILS ENGINEER. -f n, n, G) 2• MINIMUM IN BEDROCK OR APPROVED MATERIAL. 2, THE NEED FOR AND DISPOSITION OF DRAINS WOULD BE DETERMINED BY THE SOILS ENGINEER BASED UPON EXPOSED CONDITIONS. I I Ol FILL OVER CUT □ET AIL CUT/FILL CONTACT MAINTAIN MINIMUM.15'FILL SECTION FROM 1. AS SHOWN ON GRADING PLAN BACKCUT TO FACE OF FINISH SLQPE ________ _ 2. AS SHOWN ON AS· BUILT H ORIGINAL TOPOGRAPHY ....,,,\ 1~' //1\ BEDROCK OR APPROVED MATERIAL -0 r )> -I m m G) I ~ LOWEST BENCH WIDTH 15' MINIMUM OR H/2 COMPACTED FILL ~'/ .. ,~,, _, ..... -..f. 4' MINIMUM NOTE: THE CUT PORTION OF THE SLOPE SHOULD BE EXCAVATED AND EVALUATED BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST PRIOR TO CONSTRUCTING THE FILL PORTION. "lJ r )> -I rn rn G) I 00 ST AB I LIZA TION FILL FOR UNSTABLE MATERIAL EXPOSED IN PORTION OF CUT SLOPE NATURAL SLOPE REMOVE: UNSTABLE MATEijlAL / ~ r 15'.MINIMUM .,,&C~P~!;Q EINISHEQ GRADE ' 1~~ "'' .--•., UNWEATHERED BEDROCK OR APPROVED MATERIAL MATERIAL --Tull--7..::I]' MINIMUM TILTED BACK ~ w~ . lol . W L::i IF RECOMMENDED BY THE sillLS ENGINEER AND/OR ENGINEERING ~ GEOLOGIST, THE REMAINING CUT PORTION OF THE SLOPE MAY ,, __ 1:::.-;r ™ REQUIRE REMOVAL AND REPLACEMENT WITH COMPACTED FILL. NOTE: 1. SUBORAINS ARE HOT REQUIRED UNLESS SPECIFIED BY SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST, 2. ·wr SHALL BE EQUIPMENT WIDTH (15") FOR SLOPE HEIGHTS LESS THAN 25 FEET. FOR SLOPES GREATER· THAN 25 FEET ·w· SHALL BE DETERMINED BY THE PROJECT SOILS ENGINEER AND /OR ENGINEERING GEOLOGIST. AT NO TIME SHALL •w• BE LESS THAN H/2. -u -£: -i n, m· (j) I (0 SKIN FILL OF NATURAL GROUND ORIGINAL SLOPE 15• MINIMUM TO BE MAINTAINED FROM PROPOSED FINISH SLOPE FACE TO BACKCUT 3• MINIMUM I I,. . -• ···---~, ~ / MINIMUM KEY WIDTH •-~~? . ~ ... 7 p,; . ~~ J' Ml~IMUM KEY DEPTH -....--vi--1-cv1,,~ ......,,...1(/ ~~~ BEDRO(:K OR APPROVED MATERIAL NOTE: 1. THE NEED AND DISPOSITION OF DRAINS WILL BE DETERMINED! BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST BASED ON FIELD CONDITIONS. 2. PAD OVEREXCAVATION AND RECOMPACTION SHOULD BE PERFORMED IF DETERMINED TO BE NECESSARY BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST._ -0 r )> -I n, m G> I -a DAYLIGHT CUT LOT DETAIL __,---, ~ RECONSTRUCT COMPACTED FILL SLOPE AT 2:1 OR FLATTER (MAY INCREASE OR DECREASE· PAD AREA). NATURAL GRADE_,.,... _.,,,,./ ,,,-,-/ / OVEREXCAVATE AND RECOMPACT ---/ ~\\'""':.,-, \ftJi..~ / REPLACEMENT FILL OPOSEO FINISH GRADE AVOID AND/OR CLEAN UP SPILLAGE OF ~,-u'1•1/.. lJ' MINIMUM BLANKET FILL MATERIALS ON THE NATURAL SLOPE v~ // co'--'-~ _ ~W,J{\'-m'-~~u~\~\wF - NOTE: 1. 2. ~ / o''--' '/' 1~. 01" ~<:, "· q_'5,"I' N~~. iO/ W '\: '?f' BEDROCK OR APPROVED MATERIAL .:,.':-/ ~~o 'I'/ ~ / . _ YPICAL BENCHING MINIMUM --TI~.:tV ~ l!JJ · KEY DEPTH . SUBDRAIN AND KEY WIDTH REQUIREMENTS WILL BE DETERMINED BASED ON EXPOSED SUBSURFACE CONDITIONS AND THICKN~SS OF OVERBURDEN. PAD OVER EXCAVATION AND RE.COMPACTION SHOULD BE PERFORMED IF DETERMINED NECESSARY BY THij SOILS ENGINEER AND/OR THE ENGINEERING GEOLOGIST. TRANSITION LOT DETAIL CUT LOT (MATERIAL TYPE TRANSITION) - ---------- PAD GRADE COMPACTED FILL 1/\\\~ 3" MINIMUM* UNWEATHERED BEDROCK OR APPROVED MATERIAL TYPICAL BENCH ING CUT-FILL LOT (DAYLIGHT TRANSITION) NAlURAL GRADE ~~--r~~\J).\. ~~·\AJ). \ . MUM PAD GRADE ........-:: .. ~U _____ ....._ ______ __,.-,,,;-~ OVEREX·CAVATE···. ~-. · ~-· COMPACTED FILL ~ . OMPACT -------=:: -.; ,I ~\~,'\\Y-1/ 3' MINIMUM• . ____, ... ~ °'o _,----~"'o'-l . . ~ . NWEATHERED BEDROCK OR APPROVED MATERIAL CAL BENCH ING NOTE: * DEEPER OVEREXCAVATION MAY BE RECOMMENDED BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST IN STEEP CUT-FILL TRANSITION AREAS. PLATE EG-11" TEST PIT SAFETY DIAGRAM SD FEET SPOIL P1LE SIDE VIEW ( NOT TO SCALE ) TOP VIEW 100 FEET u ... 1H LI. 0 an APPROXIMATE CENTER / CF 7EST PIT I- HJ u. C In , . " .. FLAG { NOT TO SCALE ) SD FEET I I I I PLATE EG-16 APPENDIX B BORING AND TEST PIT LOGS GeoSoils, Inc. UNIFIED SOIL CLASSIFICATION SYSTEM CONSISTENCY OR RELATIVE DENSITY Major Divisions Group Symbols Typical Names CRITERIA Coarse-Grained SoilsMore than 50% retained on No. 200 sieveGravels 50% or more of coarse fraction retained on No. 4 sieveCleanGravelsGW Well-graded gravels and gravel-sand mixtures, little or no fines Standard Penetration Test Penetration Resistance N Relative (blows/ft) Density 0 - 4 Very loose 4 - 10 Loose 10 - 30 Medium 30 - 50 Dense > 50 Very dense GP Poorly graded gravels and gravel-sand mixtures, little or no fines GravelwithGM Silty gravels gravel-sand-silt mixtures GC Clayey gravels, gravel-sand-clay mixtures Sands more than 50% ofcoarse fractionpasses No. 4 sieveCleanSandsSW Well-graded sands and gravelly sands, little or no fines SP Poorly graded sands and gravelly sands, little or no fines SandswithFinesSM Silty sands, sand-silt mixtures SC Clayey sands, sand-clay mixtures Fine-Grained Soils50% or more passes No. 200 sieveSilts and ClaysLiquid limit50% or lessML Inorganic silts, very fine sands, rock flour, silty or clayey fine sands Standard Penetration Test Unconfined Penetration Compressive Resistance N Strength (blows/ft) Consistency (tons/ft 2) <2 Very Soft <0.25 2 - 4 Soft 0.25 - .050 4 - 8 Medium 0.50 - 1.00 8 - 15 Stiff 1.00 - 2.00 15 - 30 Very Stiff 2.00 - 4.00 >30 Hard >4.00 CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays OL Organic silts and organic silty clays of low plasticity Silts and ClaysLiquid limitgreater than 50%MH Inorganic silts, micaceous or diatomaceous fine sands or silts, elastic silts CH Inorganic clays of high plasticity, fat clays OH Organic clays of medium to high plasticity Highly Organic Soils PT Peat, mucic, and other highly organic soils 3" 3/4" #4 #10 #40 #200 U.S. Standard Sieve Unified Soil Classification Cobbles Gravel Sand Silt or Clay coarse fine coarse medium fine MOISTURE CONDITIONS MATERIAL QUANTITY OTHER SYMBOLS Dry Absence of moisture: dusty, dry to the touch trace 0 - 5 % C Core Sample Slightly Moist Below optimum moisture content for compaction few 5 - 10 % S SPT Sample Moist Near optimum moisture content little 10 - 25 % B Bulk Sample Very Moist Above optimum moisture content some 25 - 45 % • • Groundwater Wet Visible free water; below water table Qp Pocket Penetrometer BASIC LOG FORMAT: Group name, Group symbol, (grain size), color, moisture, consistency or relative density. Additional comments: odor, presence of roots, mica, gypsum, coarse grained particles, etc. EXAMPLE: Sand (SP), fine to medium grained, brown, moist, loose, trace silt, little fine gravel, few cobbles up to 4" in size, some hair roots and rootlets. File:Mgr: c;\SoilClassif.wpd PLATE B-1 GeoSoils, Inc. PROJECT: BNR Investment & Development, LLC Resort View Apartments APNs 216-170-14 &-15, Carlsbad Sample C u R .e: ~ ~ al ;: 0 E ~ C ~ -e it >, ~ 0 .a (/) ·c i .; (/) :::, t (/) => .; 5 "' '6 ~ l) >, '6 ., ~ '5 C (/) 0 CD => ai => ::!? (/) 0 CL 111 .9 11 .4 63.2 5 112.2 15.1 84.5 10 107.2 18.4 89.9 15 117.4 14.7 95.3 20 114.8 10.7 64.4 BORING LOG W 0. 7535-A-SC BORING B-1 SHEET 1 OF 1 ------ DATE EXCAVATED 12/12/18 LOGGED BY: RBB APPROX ELEV.: ±71' SAMPLE METHOD: Modified Cal Sampler and Standard Penetrometer, 140 lb Hammer@ Material Description ARTIFICIAL FILL: @ 0' SANDY CLAY, variegated brown and gray, moist, soft becoming stiff. @ 3' SANDY CLAY, variegated brown, dark brownish gray, reddish yellow, and light yellowish gray, moist, hard. @ 5' As per 3', wet; trace lifts of CLAYEY SAND. @ 10' CLAYEY SAND, dark brownish gray, wet, medium dense. @ 11' SAND, brown, wet, medium dense; very fine to coarse grained, trace subrounded and angular pebbles. @ 15' SANDY CLAY, variegated very dark gray, medium gray, and reddish yellow, wet, very stiff; trace subrounded and angular pebbles, trace organics. @ 20' SILTY SAND, brown, moist, dense; very fine to coarse grained. @ 21¾' SANDY CLAY, variegated bluish gray and reddish yellow, moist, ve stiff; trace or anics. QUATERNARY ALLUVIUM (REPROCESSED?): @22' SANDY CLAY, dark gray, wet to possibly saturated, soft; trace organics, organic odor. 25 ,t--~~ 25' Poor sam le recove due to cobble in the sam ler ti . .1---+---+-~·"""" .. QUATERNARY STREAM TERRACE DEPOSITS: @ 25¼' SANDY CLAYEY GRAVEL, light reddish yellow and brownish gray, damp, dense. 30 a Standard Penetration Test I Undisturbed, Ring Sample @26' SANDY CLAYEY GRAVEUGRAVELLY SANDY CLAY, yellowish brown dam dense/hard· abundant subrounded and an ular ebbles. Total Depth = 26 5/12' (Practical Refusal) No Groundwater/Caving Encountered Backfilled 12/12/2018 Groundwater GeoSoils, Inc. PLATE 2 GeoSoils, Inc. PROJECT: BNR Investment & Development, LLC Resort View Apartments APNs 216-170-14 &-15, Carlsbad Sample C u R .e: ~ ~ al ;: 0 E ~ C ~ -e it >, ~ 0 .a (/) ·c i .; (/) :::, t (/) => .; 5 "' '6 ~ l) >, '6 ., ~ '5 C (/) 0 CD => ai => ::!? (/) SM 85 SW 120.5 5.9 41 .8 SM 50-4½" SC/CL 110.0 8.0 42.3 30/ CL/ 7.1 0-5½" GC 10 15 20 25 30 a Standard Penetration Test I Undisturbed, Ring Sample BORING LOG W 0. 7535-A-SC BORING B-2 SHEET 1 OF 1 ------ DATE EXCAVATED 12/12/18 LOGGED BY: RBB APPROX ELEV.: ±70½' SAMPLE METHOD: Modified Cal Sampler and Standard Penetrometer, 140 lb Hammer@ Material Description UA TERNARY STREAM TERRACE DEPOSITS: @ O' SIL TY SAND, light reddish brown, moist, loose becoming medium dense; very fine to coarse grained, trace clay. @ 3' SAND, light reddish brown, damp, very dense; very fine to coarse grained, trace silt, trace angular pebbles. @ 4¾' SIL TY SAND, light grayish brown, damp, very dense; trace angular pebbles. @ 5' CLAYEY SAND/SANDY CLAY, brown, damp, dense/hard; abundant subangular and angular pebbles and cobbles (sample disturbed due to cobble). @ 6' GRAVELLY SANDY CLAY to SANDY CLAYEY GRAVEL, brown an ra moist hard/ve dense· abundant an ular and suban ular ebbles. Practical Refusal @ 7' No Groundwater/Caving Encountered Backfilled 12-12-2018 Groundwater GeoSoils, Inc. PLATE 3 GeoSoils, Inc. PROJECT: BNR Investment & Development, LLC Resort View Apartments APNs 216-170-14 & -15, Carlsbad Sample C u 0 ~ ~ ""C ..Q ~ ~ Q) E C: ~ -e .., >, Q) 0 .3 I!:: (/) ·c :i ~ "' ~ (/) ::::, "' -" ~ u :, '5 0 (/) >, ·o '" C: 0 CD ::::, iii ::::, ~ (/) ML 49 SM 111.6 13.5 74.0 CL/SC 49 CL 112.7 16.3 92.2 19 SC/CL 106.7 17.5 84.1 BORING LOG WO. 7535-A-SC BORING B-3 SHEET 1 OF 1 ------ DATE EXCAVATED 12/12/18 LOGGED BY: RBB APPROX. ELEV.: ±76' SAMPLE METHOD: Modified Cal Sampler and Standard Penetrometer, 140 lb Hammer@ Material Description ARTIFICIAL FILL: @ O' SANDY SILT, light gray, damp, soft becoming medium stiff. @ 3' SILTY SAND, variegated brown, light brownish gray, dark gray, and reddish yellow, moist, dense. @ 4¾' SANDY CLAY/CLAYEY SAND, variegated brown, light yellowish gray, and dark gray, moist, hard/dense. @ 5' SANDY CLAY, variegated light brown and dark brownish gray, wet, hard. @ 10' CLAYEY SAND and SANDY CLAY, variegated brown, dark gray, dark brown, and medium gray, wet, medium dense/very stiff. @ 13' Gravels encountered. 15+---l:--+---+--=--+--t----+----t,~t------------------------------l 6.4 QUATERNARY STREAM TERRACE DEPOSITS: ,1-----1--1------P'.-. @ 15' GRAVELLY SANDY CLAY/SANDY CLAYEY GRAVEL, brown and 20 25 30 ~ Standard Penetration Test I Undisturbed, Ring Sample reddish yellow, damp, hard/very dense; abundant angular and subangular ravel. Total Depth = 16' (Practical Refusal) No Groundwater/Caving Encountered Backfilled 12-12-2018 GeoSoils, Inc. Groundwater Seepage PLATE 4 0 5 10 15 20 25 30 48 37 53 50-4"77 ML SM CL SC/CL GC/ SC 104.3 105.8 114.9 93.6 8.3 21.1 13.2 13.4 37.6 99.5 79.5 ARTIFICIAL FILL:@ 0' SANDY SILT, light yellowish gray, moist, stiff. @ 3' SILTY SAND, yellow and light yellowish gray, damp, dense; very fine to fine grained. @ 5' SANDY CLAY, variegated dark brown and dark gray, saturated, very stiff. @ 10' CLAYEY SAND and SANDY CLAY, variegated brown, dark brownish gray, and light yellowish gray, moist, dense. @ 13' Gravels encountered. QUATERNARY STREAM TERRACE DEPOSITS:@ 15'GRAVELLY SANDY CLAY/SANDY CLAYEY GRAVEL, brownish gray and reddish yellow, damp, hard/dense; abundant subangular and angular pebbles, trace subangular and angular cobbles (sample disturbed due to cobble in tip of sampler).@ 15' CLAYEY SAND, grayish brown, moist, very dense; very fine to medium grained, trace angular and subangular pebbles. Total Depth = 16' No Groundwater/Caving Encountered Backfilled 12-12-2018 GeoSoils, Inc.BORING LOG PROJECT:BNR Investment & Development, LLC Resort View Apartments APNs 216-170-14 & -15, Carlsbad W.O.7535-A-SC BORING B-4 SHEET 1 OF DATE EXCAVATED 12/12/18 LOGGED BY:RBB APPROX. ELEV.:80½' SAMPLE METHOD:Modified Cal Sampler and Standard Penetrometer, 140 lb Hammer @ Standard Penetration Test Groundwater Undisturbed, Ring Sample Seepage GeoSoils, Inc. PLATE 5 Sample Material Description 1 GeoSoils, Inc. PROJECT: BNR Investment & Development, LLC Resort View Apartments APNs 216-170-14 & -15, Carlsbad Sample C u 0 ~ ~ ""C ..Q ~ ~ Q) E C: ~ -e .., >, Q) 0 .3 I!:: (/) ·c :i ~ "' ~ (/) ::::, "' -" ~ u :, '5 0 (/) >, ·o '" C: 0 CD ::::, iii ::::, ~ (/) BORING LOG WO. 7535-A-SC BORING B-5 SHEET 1 OF 1 ------ DATE EXCAVATED 12/12/18 LOGGED BY: RBB APPROX. ELEV.: ±89' SAMPLE METHOD: Modified Cal Sampler and Standard Penetrometer, 140 lb Hammer@ Material Description CL SC QUATERNARY COLLUVIUM: --+----1-----1---¼;;q_:~;"'jo~•cs;,A:',iNtrD~Ytrc~L't.AvY,,.,,, 'ft:1i ~h';+thb~ro:;:-w·n and brownish ra , moist, stiff. 70 114.2 12.4 72.9 67 SC-111.1 14.5 SP ;,:;,:~ QUATERNARY STREAM TERRACE DEPOSITS: @ 1' CLAYEY SAND, brownish gray, moist, medium dense. @ 5' CLAYEY SAND, dark brown and brownish gray, moist, dense; very fine grained. @ 10' CLAYEY SAND, variegated brown and light yellowish gray, moist, dense; very fine to fine grained grades to SAND, grayish brown, moist, dense; very fine to fine grained. 70 GW/ 108.1 SW 3.7 18.3 ~,: @ 15' SANDY GRAVEL/GRAVELLY SAND, brown, dry, dense; very fine ii.r: to coarse grained, abundant angular and subrounded pebbles. 25 30 ~ Standard Penetration Test I Undisturbed, Ring Sample 103.3 ~t; :;.Ii,:• ···"' ..... ,,,; ::«-.: ~:r::~ :~► ~~ ::.,:'Ii, :·~--6.2 27.2 • .,.. @ 20' SAND, grayish brown, damp, dense; very fine to coarse grained, trace silt, trace angular and subangular pebbles and CLAYEY SANDY GRAVEL, brown and yellow, damp, dense; abundant subangular and an ular ebbles. Total Depth= 20½' No Groundwater/Caving Encountered Backfilled 12-12-2018 GeoSoils, Inc. Groundwater Seepage PLATE 6 0 5 10 15 20 25 30 SC/CL SM SM SC GC ARTIFICIAL FILL:@ 0' CLAYEY SAND/SANDY CLAY, grayish brown, wet, loose/soft; abundant subangular pebbles and cobbles. WEATHERED QUATERNARY STREAM TERRACE DEPOSITS:@ 1' SILTY SAND, grayish brown, dry, medium dense; abundant subangular pebbles. QUATERNARY STREAM TERRACE DEPOSITS:@ 5' SILTY SAND, grayish brown, moist, dense. @ 7' CLAYEY SAND, brown, moist, dense; abundant subangular pebbles.@ 8' SANDY CLAYEY GRAVEL, brown and light brownish gray, wet, hard; abundant subangular pebbles. Total Depth = 9½' No Groundwater/Caving Encountered Backfilled 12-13-2018 GeoSoils, Inc.BORING LOG PROJECT:BNR Investment & Development, LLC Resort View Apartments APNs 216-170-14 & -15, Carlsbad W.O.7535-A-SC BORING IB-1 SHEET 1 OF DATE EXCAVATED 12/12/18 LOGGED BY:RBB APPROX. ELEV.:71½' SAMPLE METHOD: Standard Penetration Test Groundwater Undisturbed, Ring Sample Seepage GeoSoils, Inc. PLATE 7 Sample Material Description 1 GeoSoils, Inc. PROJECT: BNR Investment & Development, LLC Resort View Apartments APNs 216-170-14 & -15, Carlsbad Sample ""C ~ Q) ~ -e .3 .c "' a. -" ~ '5 Q) C: 0 CD ::::, 0 5- 10- 15- 20- 25- 30- .., I!:: ~ 0 iii 0 ..Q E >, (/) (/) u (/) ::::, SM/ CL SC CL SC ~ Standard Penetration Test I Undisturbed, Ring Sample C u ~ ~ ~ Q) ·c :i ::::, "' >, ·o 0 ~ ~ C: 0 ~ :, '" (/) . .. . .. . BORING LOG WO. 7535-A-SC BORING IB-2 SHEET 1 OF 1 ------ DATE EXCAVATED 12/12/18 LOGGED BY: RBB APPROX. ELEV.: ±73' SAMPLE METHOD: ____________________ _ Material Description . • ARTIFICIAL FILL: :: @ O' SIL TY SAND to SANDY CLAY, light gray and brown, wet becoming • damp @ 1 ', loose/soft . @ 3' CLAYEY SAND, grayish brown, dry, medium dense; abundant angular pebbles. @ 3½' SANDY CLAY, brown, damp, stiff. @ 4' SANDY CLAY, brown and dark brown, moist, stiff. @ 8' CLAYEY SAND, dark brown, moist, medium dense; fine to coarse grained, trace subangular pebbles. Total Depth = 11' No Groundwater/Caving Encountered Backfilled 12-13-2018 ~ Groundwater Q Seepage GeoSoils, Inc. PLATE 8 0 5 10 15 20 25 30 ML CL CL SM CL/SC ARTIFICIAL FILL:@ 0' SANDY SILT, light yellowish gray, damp, soft becoming medium stiff. @ 4' SANDY CLAY, brown and dark gray, moist, stiff. QUATERNARY STREAM TERRACE DEPOSITS:@ 6' SANDY CLAY, reddish brown, moist, medium dense; trace angular pebbles.@ 7' SILTY SAND, reddish brown, moist, medium dense; fine to coarse grained, trace angular pebbles.@ 8' SANDY CLAY/CLAYEY SAND, light grayish brown and light brownish gray, moist, very stiff/dense. Total Depth = 10' No Groundwater/Caving Encountered Backfilled 12-13-2018 GeoSoils, Inc.BORING LOG PROJECT:BNR Investment & Development, LLC Resort View Apartments APNs 216-170-14 & -15, Carlsbad W.O.7535-A-SC BORING IB-3 SHEET 1 OF DATE EXCAVATED 12/12/18 LOGGED BY:RBB APPROX. ELEV.:79' SAMPLE METHOD: Standard Penetration Test Groundwater Undisturbed, Ring Sample Seepage GeoSoils, Inc. PLATE 9 Sample Material Description 1 0 5 10 15 20 25 30 CL SC SM SC SM ARTIFICIAL FILL:@ 0' SANDY CLAY, grayish brown and brownish gray, wet, soft. @ 2' SANDY CLAY, brown, moist, stiff. @ 3' CLAYEY SAND, variegated brown, reddish yellow, and gray, moist, medium dense. QUATERNARY STREAM TERRACE DEPOSITS:@ 6' SILTY SAND, light brownish gray, moist, dense; very fine to fine grained.@ 7' CLAYEY SAND, light brownish gray, moist, dense; very fine to fine grained.@ 8' SILTY SAND, light brown, moist, dense; fine to coarse grained, trace subangular and angular pebbles. Total Depth = 9' No Groundwater/Caving Encountered Backfilled 12-13-2018 GeoSoils, Inc.BORING LOG PROJECT:BNR Investment & Development, LLC Resort View Apartments APNs 216-170-14 & -15, Carlsbad W.O.7535-A-SC BORING IB-4 SHEET 1 OF DATE EXCAVATED 12/12/18 LOGGED BY:RBB APPROX. ELEV.:77½' SAMPLE METHOD: Standard Penetration Test Groundwater Undisturbed, Ring Sample Seepage GeoSoils, Inc. PLATE 10 Sample Material Description 1 TP-1 0-1 1-1½ 1½-10 ML SC SM Rings@4 Bulk@5 4128-A-SC Viejo Castilla December 15, 2003 ~GOF~P~R~O~T~TPITS 5.5 101.6 E~~ST'EN(r ARTIFICIAL FILL fl:JNDOGUMENTEBt: SILT, greenish gray, moist, soft. £')(Z.S7T,,/"-) A..TrFra-41,.. F.x:-LL-(IUM: CLAYEY SAND, red brown, =t'OF'SOIL/CO LLUv v • moist, loose. A~rrt:rC.Z4L Fr.a (£~%S'7%J<i,) -SWEITZER FORMATION. STREAM TERRACE 1'1!POSITS: SILTY SAND, red brown, wet, loose to medium dense; fine to coarse grained, scattered cobble layers, rounded cobbles ~3 inches, several thin discontinuous clay layers. Total Depth = 101 No Groundwater Encountered Backfilled12-15-2003 PLATE 8-1 I -,,11mw,· . . 'A;'.:;:,,,. LOG OF EXPLORATORY TEST PITS 4128-A-SC Viejo Castilla December 15, 2003 ltt~~lrt}llll~l ~~~i~lllltlll TP-2 0-2 ML 2-4 CH Bulk@3 @4 CH Bulk@? @8 SM £ ,c:r:.srr,., 6' ARTIFICIAL FILL fUNDOCUMENTED). SILT, greenish gray, moist, soft. TOPSOIL/COLLUVIUM: CLAYEY SAND, red, moist, loose. SWEITZER FORMATION. STREAM TERRACE DEPOSITS: CLAY, red brown, moist,very stiff; scattered cobbles and sand. SILTY SAND, red brown, moist, medium dense; scattered cobbles'. Total Depth= 91 No Groundwater Encountered Backfilled 4-15-2003 PLATE 8·2 LOG OF EXPLORATORY TEST PITS 4128-A-SC Viejo Castilla December 15, 2003 1?t{Itiii11~ I j1I, ti~t{i ! r11;~I it~1iil iifrf il l :-ii:.\i:••::.,-::::\:J:j-:.C:~~-f;'j;·,I,.'.(),::~•~x TP-3 0-1 ML 1-4 SM . E~rsrr,./~ ARTIFICIAL FILL (UNDOCUMENTED); SILT, greenish gray, moist, soft. A~rzpz;.ci::.1tL FrLL-( c'lt~,rr-"'lr) SWEITZER FORMATION. STREAM DEPOSITS:-SILTY SAND, red brown, moist, loose to medium dense; abundant cobbles. Total Depth = 41 · No Groundwater Encountered Backfilled 4-15-2003 PLATE B-3 I ·w@r 'J;2!;;.,," • LOG OF EXPLORATORY TEST PITS 4128-A-SC Viejo Castilla December 15, 2003 ~~f ~~I ~~;11 l~i~~1,~1t~ lk~~,, '1111~1i''!i'~t')l,~]'~:~,~g:i,i'.~1~J"J:~:i .. f ,~lxI••=:::·::~'.:l•L';,!~~~h,:'. TP-4 0-1 CL 1-4 CLJSC 5-6 ML TOPSOIL/COLLUVIUM: SANDY CLAY, red brown, moist, soft; scattered cobbles. SWEITZER FORMATION. STREAM TERRACE DEPOSITS: SANDY CLAY, red brown, moist, stiff. SILT, light red brown, moist, stiff. Total Depth = 6' No Groundwater Encountered Backfilled 12-15-2003 PLATE 8-4 APPENDIXC UPDATED SEISMICITY GeoSoils, Inc. *********************** * * * E Q F A U L T * * * * Version 3.00 * * * *********************** DETERMINISTIC ESTIMATION OF PEAK ACCELERATION FROM DIGITIZED FAULTS JOB NUMBER: 7535-A-SC DATE: 12-15-2018 JOB NAME: BNR INVESTMENT AND DEVELOPMENT, LLC CALCULATION NAME: 7535 FAULT-DATA-FILE NAME: C:\Program Files\EQFAULT1\CGSFLTE.DAT SITE COORDINATES: SITE LATITUDE: 33.0882 SITE LONGITUDE: 117.2519 SEARCH RADIUS: 62.2 mi ATTENUATION RELATION: 11) Bozorgnia Campbell Niazi (1999) Hor.-Pleist. Soil-Cor. UNCERTAINTY (M=Median, S=Sigma): S Number of Sigmas: 1.0 DISTANCE MEASURE: cdist SCOND: 0 Basement Depth: 5.00 km Campbell SSR: 0 Campbell SHR: 0 COMPUTE PEAK HORIZONTAL ACCELERATION FAULT-DATA FILE USED: C:\Program Files\EQFAULT1\CGSFLTE.DAT MINIMUM DEPTH VALUE (km): 3.0 Page 1 W.O. 7535-A-SC PLATE C-1 --------------- EQFAULT SUMMARY --------------- ----------------------------- DETERMINISTIC SITE PARAMETERS ----------------------------- Page 1 ------------------------------------------------------------------------------- | |ESTIMATED MAX. EARTHQUAKE EVENT | APPROXIMATE |------------------------------- ABBREVIATED | DISTANCE | MAXIMUM | PEAK |EST. SITE FAULT NAME | mi (km) |EARTHQUAKE| SITE |INTENSITY | | MAG.(Mw) | ACCEL. g |MOD.MERC. ================================|==============|==========|==========|========= ROSE CANYON | 6.5( 10.4)| 7.2 | 0.555 | X NEWPORT-INGLEWOOD (Offshore) | 11.4( 18.4)| 7.1 | 0.348 | IX CORONADO BANK | 21.3( 34.3)| 7.6 | 0.271 | IX ELSINORE (JULIAN) | 24.4( 39.2)| 7.1 | 0.170 | VIII ELSINORE (TEMECULA) | 24.4( 39.2)| 6.8 | 0.139 | VIII ELSINORE (GLEN IVY) | 38.8( 62.4)| 6.8 | 0.086 | VII EARTHQUAKE VALLEY | 39.4( 63.4)| 6.5 | 0.069 | VI PALOS VERDES | 42.1( 67.7)| 7.3 | 0.111 | VII SAN JOAQUIN HILLS | 42.2( 67.9)| 6.6 | 0.097 | VII SAN JACINTO-ANZA | 47.1( 75.8)| 7.2 | 0.092 | VII SAN JACINTO-SAN JACINTO VALLEY | 49.1( 79.0)| 6.9 | 0.072 | VI SAN JACINTO-COYOTE CREEK | 50.1( 80.6)| 6.6 | 0.057 | VI ELSINORE (COYOTE MOUNTAIN) | 52.3( 84.1)| 6.8 | 0.063 | VI NEWPORT-INGLEWOOD (L.A.Basin) | 52.9( 85.2)| 7.1 | 0.076 | VII CHINO-CENTRAL AVE. (Elsinore) | 53.9( 86.7)| 6.7 | 0.080 | VII WHITTIER | 57.8( 93.0)| 6.8 | 0.056 | VI SAN JACINTO - BORREGO | 61.8( 99.4)| 6.6 | 0.046 | VI ******************************************************************************* -END OF SEARCH- 17 FAULTS FOUND WITHIN THE SPECIFIED SEARCH RADIUS. THE ROSE CANYON FAULT IS CLOSEST TO THE SITE. IT IS ABOUT 6.5 MILES (10.4 km) AWAY. LARGEST MAXIMUM-EARTHQUAKE SITE ACCELERATION: 0.5549 g Page 2 W.O. 7535-A-SC PLATE C-2 SITE -100 0 100 200 300 400 500 600 700 800 900 1000 1100 -400 -300 -200 -100 0 100 200 300 400 500 600 CALIFORNIA FAULT MAP BNR INVESTMENT AND DEVELOPMENT, LLC W.O. 7535-A-SC PLATE C-3 .001 .01 .1 1 .1 1 10 100 MAXIMUM EARTHQUAKES BNR INVESTMENT AND DEVELOPMENT, LLC Distance (mi) W.O. 7535-A-SC PLATE C-4 ************************* * * * E Q S E A R C H * * * * Version 3.00 * * * ************************* ESTIMATION OF PEAK ACCELERATION FROM CALIFORNIA EARTHQUAKE CATALOGS JOB NUMBER: 7535-A-SC DATE: 12-15-2018 JOB NAME: BNR INVESTMENT AND DEVELOPMENT, LLC EARTHQUAKE-CATALOG-FILE NAME: ALLQUAKE.DAT SITE COORDINATES: SITE LATITUDE: 33.0882 SITE LONGITUDE: 117.2519 SEARCH DATES: START DATE: 1800 END DATE: 2018 SEARCH RADIUS: 62.2 mi 100.1 km ATTENUATION RELATION: 11) Bozorgnia Campbell Niazi (1999) Hor.-Pleist. Soil-Cor. UNCERTAINTY (M=Median, S=Sigma): S Number of Sigmas: 1.0 ASSUMED SOURCE TYPE: SS [SS=Strike-slip, DS=Reverse-slip, BT=Blind-thrust] SCOND: 0 Depth Source: A Basement Depth: 5.00 km Campbell SSR: 0 Campbell SHR: 0 COMPUTE PEAK HORIZONTAL ACCELERATION MINIMUM DEPTH VALUE (km): 3.0 Page 1 W.O. 7535-A-SC PLATE C-5 ------------------------- EARTHQUAKE SEARCH RESULTS ------------------------- Page 1 ------------------------------------------------------------------------------- | | | | TIME | | | SITE |SITE| APPROX. FILE| LAT. | LONG. | DATE | (UTC) |DEPTH|QUAKE| ACC. | MM | DISTANCE CODE| NORTH | WEST | | H M Sec| (km)| MAG.| g |INT.| mi [km] ----+-------+--------+----------+--------+-----+-----+-------+----+------------ DMG |33.0000|117.3000|11/22/1800|2130 0.0| 0.0| 6.50| 0.381 | X | 6.7( 10.8) MGI |33.0000|117.0000|09/21/1856| 730 0.0| 0.0| 5.00| 0.069 | VI | 15.8( 25.4) MGI |32.8000|117.1000|05/25/1803| 0 0 0.0| 0.0| 5.00| 0.050 | VI | 21.8( 35.0) DMG |32.7000|117.2000|05/27/1862|20 0 0.0| 0.0| 5.90| 0.069 | VI | 27.0( 43.4) T-A |32.6700|117.1700|12/00/1856| 0 0 0.0| 0.0| 5.00| 0.037 | V | 29.3( 47.1) T-A |32.6700|117.1700|10/21/1862| 0 0 0.0| 0.0| 5.00| 0.037 | V | 29.3( 47.1) T-A |32.6700|117.1700|05/24/1865| 0 0 0.0| 0.0| 5.00| 0.037 | V | 29.3( 47.1) DMG |33.2000|116.7000|01/01/1920| 235 0.0| 0.0| 5.00| 0.033 | V | 32.8( 52.8) DMG |32.8000|116.8000|10/23/1894|23 3 0.0| 0.0| 5.70| 0.050 | VI | 32.9( 52.9) PAS |32.9710|117.8700|07/13/1986|1347 8.2| 6.0| 5.30| 0.035 | V | 36.7( 59.0) MGI |33.2000|116.6000|10/12/1920|1748 0.0| 0.0| 5.30| 0.033 | V | 38.5( 61.9) DMG |33.7000|117.4000|05/15/1910|1547 0.0| 0.0| 6.00| 0.045 | VI | 43.1( 69.3) DMG |33.7000|117.4000|04/11/1910| 757 0.0| 0.0| 5.00| 0.025 | V | 43.1( 69.3) DMG |33.7000|117.4000|05/13/1910| 620 0.0| 0.0| 5.00| 0.025 | V | 43.1( 69.3) DMG |33.6990|117.5110|05/31/1938| 83455.4| 10.0| 5.50| 0.032 | V | 44.7( 72.0) DMG |33.7100|116.9250|09/23/1963|144152.6| 16.5| 5.00| 0.023 | IV | 46.9( 75.4) DMG |33.0000|116.4330|06/04/1940|1035 8.3| 0.0| 5.10| 0.024 | IV | 47.8( 76.9) DMG |33.7500|117.0000|06/06/1918|2232 0.0| 0.0| 5.00| 0.022 | IV | 47.9( 77.1) DMG |33.7500|117.0000|04/21/1918|223225.0| 0.0| 6.80| 0.068 | VI | 47.9( 77.1) GSG |33.4200|116.4890|07/07/2010|235333.5| 14.0| 5.50| 0.029 | V | 49.6( 79.9) GSP |33.5290|116.5720|06/12/2005|154146.5| 14.0| 5.20| 0.024 | V | 49.6( 79.9) DMG |33.8000|117.0000|12/25/1899|1225 0.0| 0.0| 6.40| 0.049 | VI | 51.2( 82.5) PAS |33.5010|116.5130|02/25/1980|104738.5| 13.6| 5.50| 0.028 | V | 51.3( 82.5) GSP |33.5080|116.5140|10/31/2001|075616.6| 15.0| 5.10| 0.022 | IV | 51.5( 82.9) DMG |33.5000|116.5000|09/30/1916| 211 0.0| 0.0| 5.00| 0.020 | IV | 51.9( 83.5) GSP |33.4315|116.4427|06/10/2016|080438.7| 12.3| 5.19| 0.023 | IV | 52.4( 84.3) MGI |33.8000|117.6000|04/22/1918|2115 0.0| 0.0| 5.00| 0.020 | IV | 53.1( 85.4) DMG |33.5750|117.9830|03/11/1933| 518 4.0| 0.0| 5.20| 0.022 | IV | 53.9( 86.8) DMG |33.6170|117.9670|03/11/1933| 154 7.8| 0.0| 6.30| 0.042 | VI | 55.1( 88.6) DMG |33.3430|116.3460|04/28/1969|232042.9| 20.0| 5.80| 0.031 | V | 55.2( 88.8) DMG |33.9000|117.2000|12/19/1880| 0 0 0.0| 0.0| 6.00| 0.034 | V | 56.1( 90.3) DMG |33.6170|118.0170|03/14/1933|19 150.0| 0.0| 5.10| 0.020 | IV | 57.3( 92.2) DMG |33.4000|116.3000|02/09/1890|12 6 0.0| 0.0| 6.30| 0.039 | V | 59.0( 95.0) T-A |32.2500|117.5000|01/13/1877|20 0 0.0| 0.0| 5.00| 0.018 | IV | 59.6( 96.0) DMG |33.2000|116.2000|05/28/1892|1115 0.0| 0.0| 6.30| 0.038 | V | 61.3( 98.6) DMG |33.4080|116.2610|03/25/1937|1649 1.8| 10.0| 6.00| 0.031 | V | 61.3( 98.7) DMG |32.7000|116.3000|02/24/1892| 720 0.0| 0.0| 6.70| 0.049 | VI | 61.3( 98.7) DMG |33.6830|118.0500|03/11/1933| 658 3.0| 0.0| 5.50| 0.023 | IV | 61.7( 99.2) ******************************************************************************* -END OF SEARCH- 38 EARTHQUAKES FOUND WITHIN THE SPECIFIED SEARCH AREA. TIME PERIOD OF SEARCH: 1800 TO 2018 LENGTH OF SEARCH TIME: 219 years THE EARTHQUAKE CLOSEST TO THE SITE IS ABOUT 6.7 MILES (10.8 km) AWAY. LARGEST EARTHQUAKE MAGNITUDE FOUND IN THE SEARCH RADIUS: 6.8 Page 2 W.O. 7535-A-SC PLATE C-6 LARGEST EARTHQUAKE SITE ACCELERATION FROM THIS SEARCH: 0.381 g COEFFICIENTS FOR GUTENBERG & RICHTER RECURRENCE RELATION: a-value= 0.562 b-value= 0.302 beta-value= 0.695 ------------------------------------ TABLE OF MAGNITUDES AND EXCEEDANCES: ------------------------------------ Earthquake | Number of Times | Cumulative Magnitude | Exceeded | No. / Year -----------+-----------------+------------ 4.0 | 38 | 0.17431 4.5 | 38 | 0.17431 5.0 | 38 | 0.17431 5.5 | 17 | 0.07798 6.0 | 10 | 0.04587 6.5 | 3 | 0.01376 Page 3 W.O. 7535-A-SC PLATE C-7 SITE LEGEND M = 4 M = 5 M = 6 M = 7 M = 8 -100 0 100 200 300 400 500 600 700 800 900 1000 1100 -400 -300 -200 -100 0 100 200 300 400 500 600 EARTHQUAKE EPICENTER MAP BNR INVESTMENT AND DEVELOPMENT, LLC W.O. 7535-A-SC PLATE C-8 .001 .01 .1 1 10 100 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 EARTHQUAKE RECURRENCE CURVE BNR INVESTMENT AND DEVELOPMENT, LLC Magnitude (M) W.O. 7535-A-SC PLATE C-9 APPENDIX D INFILTRATION TEST DATA AND WORKSHEETS GeoSoils, Inc. W.O. 7535-A-SC PLATE D-1 I rJ ~ 7.5 M IO 40. s-3. 2!:" 3. o B /0: 3/.,Afl'I /0 J 'J. .:?&.. z~ '-/.ZS-Z.35' /0~'/tAM /() 3 9-,S" 'fo.S 3 1_.33 /(): {i A"'1 /0 3-=,-'lo 3 3.33 IO -'S''1 AM /1: 179AM /0 3":f.15" '-!o.7-S" 3 3,33 COMMENTS: Table 5 -Sample Test Data Form for Percolation Test Riverside County -Low Impact Development BMP Design Handbook rev. 9/2011 Page 25 W.O. 7535-A-SC PLATE D-2 /IM 10:Z{,,lfl"I 0 3o.1S- At>1 ;o:39,im /0 31 /(?:,sOAM /0 29. ·5" 2.~ if- //; 0/ ~"1 I tJ 29-.5' 29, 95' 2,ZS" t/.t/ 11:JZAt11 10 '2-1 2'1.2;[ 2.2s-l/. lf'/f COMMENTS: Table 5-Sample Test Data Form for Percolation Test Riverside County -Low Impact Development BMP Design Handbook rev. 9/2011 Page25 W.O. 7535-A-SC PLATE D-3 2. ,:;- 2-3(,. -Z> -2~ ;z.. 3 5' /0 3'1 37-.5' 3~::-2-B' 10 33.~ 3h ,S 3 .3,33 /0 33 3 G • 'Z '5' :.s ~ L. $"" 3.06 /I} 2.s 3545" 3 3,33 COMMENTS: Table 5 -Sample Test Data Form for Percolation Test Riverside County -Low Impact Development BMP Design Handbook rev. 9/2011 Page 25 W.O. 7535-A-SC PLATE D-4 , 5 30 23 21./. 5" I.§'" zo 30 Z.Z,S 7--'{ /.~ zo 3o 2'2. 23. -:;S" /,1-5' Fl.IL/ 30 22 23.$"' /. s-zo 30 2¥ /,5" zo 'Z,J. 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Cit" V f ~ ' ' I IH Tl" I I ~ l t:; >-'V !. I< II Ali I I ... / I] 'C I --') I f·---· ,-lo' .. -,_ ,. v, ,, I ..._ I ' ~ ,,._ l L NC-/1 I I I I I I -r, -I I I. I OJI~ I ~ / . I I I I r-' 'II .., --I I i I I I .. .l 11 -· ~✓ ,r-.J Vb' I I I I I I I ! I I I ~ 11 I I I I 1 r7 .J. ,, ,,. >/ ., ·-I ! I I I ! -., I I.\" 7 lu /,' ~N Uh~ I I I I I I r,,, ' p-,..--I ~ I i I ,_,. .. --4-· . f J II .," l,£~1l In c;.,J I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I -I I I I I ,-~-I I I I I I I i ' I I I W.O. 7535-A-SC PLATE D-7 8N R · TN v€ST/r1€t-l'r CLIENT:AwO IX'f'£Lpff't1li1'1. LLC . I I I PROJECT: &sol<..T Vr~w SHEET / OF I -------------- CALCULATED BY: f? 6 DATE: 12b-=rh 8 ------I I CHECKED BY: DATE: ------------- SCALE: NON€. I -·~ , I 1-+-+-t-l-t-+-+-+-r-+-+-t-.r. -,(\/j.f 71 ~ I II< )~ I 1 t) I'\ IC I 11 V I /'1 JU '-,.. IC { ~ II t •Jl,\li~, I I I I I I _J,,'I I I ,/,. ·'" T l u' I HJ , 1/1 / / I '/ r f ,r~T { 11I V,il<. ::>.J.,.,, I ,,, r;. J1(U I Li? ,r, I , ,,,, o t) · 1.t rr, P<I ~Jll-11(' IL.L. ,-.J."'f '1 ,-I \I I I l 1. ...11/ I I I I I -1 '/ I\ .J. A r I. I .IIKIA /I/lo/ ..,.,.. I I JI J ,.,,\. ,. ,I'\ 1 7 ,.., /) I j\ I I 1 \ I f ,, NC, t "' r j ,.. --/ I I I ' ,_ '\ l . f _l ' I I - Ill H I ) I I l T I A f I t I -,. I I I , ·"" -1.i.""' t: t:.~ u, <=-'-,,rr \J. '-"" l / II i., u • I i I ,,.. jl 1 I lh I/-" 7 I I I I I I I I >-+-+-+-+-+-+-+-+-t-+-+-+-+--a-+-+-+-t-+-+-+-+-'-+--+-+-+-+-+-+--a-+-+--+-+-+1-+--+-+--a-+-+-+-a-+-+-+-t-t-·-· ···---·-I I i-+-+-+-i-+-+-+-l-+-+--+-~1-+-+-il-+-+-+-1-+-1--'+1-~+-~~-+--+-+--+-+~l1-+~l1-+-+--'-+-+1-+-+-+--t-+-+-+-i1-+-+•~,~-,-+-+-i:1-+-+-+-i-+-++:-+-+-+-1•--- W.O. 7535-A-SC PLATE D-8 SHEET / OF / --~--'----------- CALCULATED BY: f? 6 DATE: 12.../17/18 ------. . CHECKED BY: DATE: ------------- 8flR 71JvESTM£t11 CLIENT: AND DE'f€l.Of'M€1JT; LJ..C PROJECT: R6SlJR. r 1/2-e-w " W.O. 7535"-A-SC SCALE: Mo/VE I I I I I I I I I I I I -! 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L ;~ '\ ,-,. l ; ,, ;i. u:s ., --L'l J , { --, _.. .I , . -\ ·, ') ~ T j I I\ I -, I• ) I I -"<.A DT 111, I J-" I a'I_ . ~ 'l, ~J•c,,./ I ' I IA --H. , -~ I A , ... ,. I I I. I I f1 11, .. f E' l<..,J 'r L'I-II' :-, I crcv C: } -~ 1, -ILi/- ~ --" I I I .,,, -IL. , I I._ ,r. -', I' . ' . .CIC. t: I ti-I :; I C.J.. , rr I,,. CII"' I I l -r I I 1m .r,11 H IE> ';I/ ~ f( VAIi •r' I ( I ,-1 I I -I .11 ... LIii/ I<-n L 'J :, I I ~'ti r-1 /•....J I \ I 'NC!-/ I I I I I ✓ I . I J (}{',_ I,., . I I I I I I , ,~ ... I I l.j ,l -t I• ~ . ~ "' IC{-'E,~ I I I I I I I .,,. ' I I I I I 'l I L NJ<-Ii It" I I I I ' ·-. 1 ,. 7 L I 'I c.,V .I I c;:.. I I -... -, .- ',,j,_ . ~ _. L ""< ,, C J I ! I I I ' I I I I I I I \ I I I I I I I I I I I I I I ---I I W.O. 7535-A-SC PLATE D-9 W.O. 7535-A-SC PLATE D-10 W.O. 7535-A-SC PLATE D-11 W.O. 7535-A-SC PLATE D-12 W.O. 7535-A-SC PLATE D-13 APPENDIX E LABORATORY TEST RESULTS GeoSoils, Inc. Tested By: TR Checked By: TR LIQUID AND PLASTIC LIMITS TEST REPORT PLASTICITY INDEX0 10 20 30 40 50 60 LIQUID LIMIT 0 10 20 30 40 50 60 70 80 90 100 110 CL-ML CL or OLCH or OHML or OL MH or OH Dashed line indicates the approximate upper limit boundary for natural soils 47 SOIL DATA SYMBOL SOURCE NATURAL USCSSAMPLE DEPTH WATER PLASTIC LIQUID PLASTICITY NO. CONTENT LIMIT LIMIT INDEX (%) (%) (%) (%) Client: Project: Project No.: Plate BNR Investment Resort View Apartments 7535-A-SC E-1 B-1 B-1 1-4 - 13 49 36 CL B-3 B-3 10.0 - 12 37 25 CL B-4 B-4 5.0 - 14 44 30 CL Boring Number:B-1 Date Started: 1/21/2019 Sample Number: Date Completed: 1/22/2019 5.0 Tested By: TR Dark Brown Sandy Clay Date Received: 12/12/2018 By: RB H20 added ksf Load ksf Swell % Dry Density* pcf MC Initial % MC Final % Initial Saturat. % Final Saturat. % 1 0.5 0.5 1.49 113.8 15.1 17.4 86.1 99.8 2 1.5 1.5 0.88 114.3 15.1 17.0 87.5 99.6 3 2.5 2.5 -0.91 111.9 15.1 18.3 81.9 99.9 * Test samples from undisturbed ring samples GeoSoils, Inc. 5741 Palmer Way Project:BNR Investment Carlsbad, CA 92010 Telephone: (760) 438-3155 Number:7535-A-SC 9/2/2010 Date:January 2019 Plate: E-2 SWELL PRESSURE TEST RESULTS Depth (ft.): Sample Description: SWELL PRESSURE TEST General Accordance with ASTM D4546 Method A -4.00 -3.00 -2.00 -1.00 0.00 1.00 2.00 0 0.5 1 1.5 2 2.5 3Swell %Load ksf Percent Swell Tested By:TR Checked By: TR Client:BNR Investment Project: Resort View Apartments Source of Sample: B-3 Depth: 5-10 Sample Number: B-3 Proj. No.: 7535-A-SC Date Sampled: Sample Type: Remolded Shear Description: Dark Brown Sandy Clay Specific Gravity= 2.7 Remarks:1-9-19 Plate E-3 Sample No. Water Content, % Dry Density, pcf Saturation, % Void Ratio Diameter, in. Height, in. Water Content, % Dry Density, pcf Saturation, % Void Ratio Diameter, in. Height, in. Normal Stress, psf Fail. Stress, psf Strain, % Ult. Stress, psf Strain, % Strain rate, in./min.InitialAt TestShear Stress, psf0 250 500 750 1000 1250 1500 Strain, % 0 5 10 15 20 1 2 3Ult. Stress, psf Fail. Stress, psf 0 500 1000 1500 Normal Stress, psf 0 500 1000 1500 2000 2500 3000 C, psf , deg Tan() Fail. Ult. 148 25.8 0.48 90 26.5 0.50 1 10.4 112.6 56.6 0.4965 2.38 1.00 17.9 112.9 98.1 0.4935 2.38 1.00 550 455 2.6 410 9.2 0.001 2 10.4 113.0 57.1 0.4914 2.38 1.00 17.7 113.7 99.2 0.4824 2.38 0.99 1100 617 5.9 569 11.8 0.001 3 10.4 112.9 56.9 0.4934 2.38 1.00 17.4 114.1 98.7 0.4770 2.38 0.99 2200 1231 8.9 1210 11.3 0.001 Tested By: TR Checked By: TR CONSOLIDATION TEST REPORT Percent Strain8 7 6 5 4 3 2 1 0 -1 -2 Applied Pressure - psf 100 1000 10000 Water Added Natural Dry Dens.LL PI Sp. Gr. USCS AASHTO Initial Void Saturation Moisture (pcf) Ratio 88.3 % 18.3 % 108.0 2.7 SC 0.561 Dark Brown Clayey Sand 7535-A-SC BNR Investment Resort View Apartments 1-8-19 MATERIAL DESCRIPTION Project No. Client:Remarks: Project: Source of Sample: B-1 Depth: 10.0 Sample Number: B-1 Plate Tested By: TR Checked By: TR CONSOLIDATION TEST REPORT Percent Strain8 7 6 5 4 3 2 1 0 -1 -2 Applied Pressure - psf 100 1000 10000 Water Added Natural Dry Dens.LL PI Sp. Gr. USCS AASHTO Initial Void Saturation Moisture (pcf) Ratio 92.3 % 17.5 % 111.5 37 25 2.7 CL 0.512 Dark Brown Sandy Clay 7535-A-SC BNR Investment Resort View Apartments 1-8-19 E-5 MATERIAL DESCRIPTION Project No. Client:Remarks: Project: Source of Sample: B-3 Depth: 10.0 Sample Number: B-3 Plate Tested By: TR Checked By: TR CONSOLIDATION TEST REPORT Percent Strain7 6 5 4 3 2 1 0 -1 -2 -3 Applied Pressure - psf 100 1000 10000 Water Added Natural Dry Dens.LL PI Sp. Gr. USCS AASHTO Initial Void Saturation Moisture (pcf) Ratio 98.9 % 19.5 % 110.0 44 30 2.7 CL 0.532 Dark Brown Sandy Clay 7535-A-SC BNR Investment Resort View Apartments 1-11-19 E-6 MATERIAL DESCRIPTION Project No. Client:Remarks: Project: Source of Sample: B-4 Depth: 5.0 Sample Number: B-4 Plate M. J. Schiff & AslJociates, Inc. c,,,,s11lting Corrosion Engi11ctr.i. Since /.95.9 43 I Jf'. 8mieline Rflad Claremont, CA 91711 Pllnn~: (909) 616-Q967 Fax: (909) 626-JJ/6 E-mail /ah@mjsclt lff. cnm 111eb.'ilte: mj.rcl1iff.cum Sample ID Re:.l:;tlvi1.y as-received saturarcd pH Elei:tritnl Conductivity Chemical Analy~11~ Cntions calcium cn2'· magnesium Mg2 '· sodium Na11· Anions carbonocc CO l· ,1 Table 1 -1...aborstory Tests or1 Soil Samples S~a Unit! ohm-cm ohm-cm mStcm mg/kg mglkg mg/kg m.g/kg J'n11r #41.28-A-SC, MJS&A /103-15511.AB 2-Jnn-04 79,000 9,600 7.5 0.0,5 12 ND 6 ND bicarbonate HC011' mg/kg 52 chloride c1'· mg/kg ND sulfotc so/ mg/kg ND Other Te,b am111onium NH/' rrig/kg na nitrnrc N01 1" mg/kg na sulfide sl• qual na R~dox mv .Oil ~1,,Ki!f .. _i~1~~>:Q~.~·:9:8',&t .. 5!6'"ri.to.l':•.t™9ii;-:rJl~S.0~4,Nt;.:Q&JiN.t.-JU;li.:~.t~ktftiX9-J:~ft.¢.di!M!\£ffif.is\Gb~!Si.S-i'L"\6Sr..\!i&fif.F,&£~iii4 Electrical conductivity in millisiem.ens/em and chemicnl analysis were mode on a 1:5 soil-to-water extract. mg/kg= milligrams per kilogram (parts per million) of dry soil. Redox = oxidation-reduction potential in millivolts NI) "' no1 detected na = not analyzed Figure 1 Pngc I of I APPENDIX F GENERAL EARTHWORK AND GRADING GUIDELINES GeoSoils, Inc. GENERAL EARTHWORK AND GRADING GUIDELINES General These guidelines present general procedures and requirements for earthwork and grading as shown on the approved grading plans, including preparation of areas to be filled, placement of fill, installation of subdrains, excavations, and appurtenant structures or flatwork. The recommendations contained in the geotechnical report are part of these earthwork and grading guidelines and would supercedethe provisions contained hereafter in the case of conflict. Evaluations performed by the consultant during the course of grading may result in new or revised recommendations which could supercede these guidelines or the recommendations contained in the geotechnical report. Generalized details follow this text. The contractor is responsible for the satisfactory completion of all earthwork in accordance with provisions of the project plans and specifications and latest adopted code. In the case of conflict, the most onerous provisions shall prevail. The project geotechnical engineer and engineering geologist (geotechnical consultant), and/or their representatives, should provide observation and testing services, and geotechnical consultation during the duration of the project. EARTHWORK OBSERVATIONS AND TESTING Geotechnical Consultant Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer and engineering geologist) should be employed for the purpose of observing earthwork procedures and testing the fills for general conformance with the recommendations of the geotechnical report(s), the approved grading plans, and applicable grading codes and ordinances. The geotechnical consultant should provide testing and observation so that an evaluation may be made that the work is being accomplished as specified. It is the responsibility of the contractor to assist the consultants and keep them apprised of anticipated work schedules and changes, so that they may schedule their personnel accordingly. All remedial removals, clean-outs, prepared ground to receive fill, key excavations, and subdrain installation should be observed and documented by the geotechnical consultant prior to placing any fill. It is the contractor's responsibility to notify the geotechnical consultant when such areas are ready for observation. Laboratory and Field Tests Maximum dry density tests to determine the degree of compaction should be performed in accordance with American Standard Testing Materials test method ASTM designation D-1557. Random or representative field compaction tests should be performed in GeoSoils, Inc. accordance with test methods ASTM designation D-1556, D-2937 or D-2922, and D-3017, at intervals of approximately ±2 feet of fill height or approximately every 1,000 cubic yards placed. These criteria would vary depending on the soil conditions and the size of the project. The location and frequency of testing would be at the discretion of the geotechnical consultant. Contractor's Responsibility All clearing, site preparation, and earthwork performed on the project should be conducted by the contractor, with observation by a geotechnical consultant, and staged approval by the governing agencies, as applicable. It is the contractor's responsibility to prepare the ground surface to receive the fill, to the satisfaction of the geotechnical consultant, and to place, spread, moisture condition, mix, and compact the fill in accordance with the recommendations of the geotechnical consultant. The contractor should also remove all non-earth material considered unsatisfactory by the geotechnical consultant. Notwithstanding the services provided by the geotechnical consultant, it is the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the earthwork in strict accordance with applicable grading guidelines, latest adopted codes or agency ordinances, geotechnical report(s), and approved grading plans. Sufficient watering apparatus and compaction equipment should be provided by the contractor with due consideration for the fill material, rate of placement, and climatic conditions. If, in the opinion of the geotechnical consultant, unsatisfactory conditions such as questionable weather, excessive oversized rock or deleterious material, insufficient support equipment, etc., are resulting in a quality of work that is not acceptable, the consultant will inform the contractor, and the contractor is expected to rectify the conditions, and if necessary, stop work until conditions are satisfactory. During construction, the contractor shall properly grade all surfaces to maintain good drainage and prevent ponding of water. The contractor shall take remedial measures to control surface water and to prevent erosion of graded areas until such time as permanent drainage and erosion control measures have been installed. SITE PREPARATION All major vegetation, including brush, trees, thick grasses, organic debris, and other deleterious material, should be removed and disposed of off-site. These removals must be concluded prior to placing fill. In-place existing fill, soil, alluvium, colluvium, or rock materials, as evaluated by the geotechnical consultant as being unsuitable, should be removed prior to any fill placement. Depending upon the soil conditions, these materials may be reused as compacted fills. Any materials incorporated as part of the compacted fills should be approved by the geotechnical consultant. Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic tanks, wells, pipelines, or other structures not located prior to grading, are to be removed BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 2 or treated in a manner recommended by the geotechnical consultant. Soft, dry, spongy, highly fractured, or otherwise unsuitable ground, extending to such a depth that surface processing cannot adequately improve the condition, should be overexcavated down to firm ground and approved by the geotechnical consultant before compaction and filling operations continue. Overexcavated and processed soils, which have been properly mixed and moisture conditioned, should be re-compacted to the minimum relative compaction as specified in these guidelines. Existing ground, which is determined to be satisfactory for support of the fills, should be scarified (ripped) to a minimum depth of 6 to 8 inches, or as directed by the geotechnical consultant. After the scarified ground is brought to optimum moisture content, or greater and mixed, the materials should be compacted as specified herein. If the scarified zone is greater than 6 to 8 inches in depth, it may be necessary to remove the excess and place the material in lifts restricted to about 6 to 8 inches in compacted thickness. Existing ground which is not satisfactory to support compacted fill should be overexcavated as required in the geotechnical report, or by the on-site geotechnical consultant. Scarification, disc harrowing, or other acceptable forms of mixing should continue until the soils are broken down and free of large lumps or clods, until the working surface is reasonably uniform and free from ruts, hollows, hummocks, mounds, or other uneven features, which would inhibit compaction as described previously. Where fills are to be placed on ground with slopes steeper than 5:1 (h:v), the ground should be stepped or benched. The lowest bench, which will act as a key, should be a minimum of 15 feet wide and should be at least 2 feet deep into firm material, and approved by the geotechnical consultant. In fill-over-cut slope conditions, the recommended minimum width of the lowest bench or key is also 15 feet, with the key founded on firm material, as designated by the geotechnical consultant. As a general rule, unless specifically recommended otherwise by the geotechnical consultant, the minimum width of fill keys should be equal to ½ the height of the slope. Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable material. Benching may be used to remove unsuitable materials, although it is understood that the vertical height of the bench may exceed 4 feet. Pre-stripping may be considered for unsuitable materials in excess of 4 feet in thickness. All areas to receive fill, including processed areas, removal areas, and the toes of fill benches, should be observed and approved by the geotechnical consultant prior to placement of fill. Fills may then be properly placed and compacted until design grades (elevations) are attained. COMPACTED FILLS Any earth materials imported or excavated on the property may be utilized in the fill provided that each material has been evaluated to be suitable by the geotechnical BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 3 consultant. These materials should be free of roots, tree branches, other organic matter, or other deleterious materials. All unsuitable materials should be removed from the fill as directed by the geotechnical consultant. Soils of poor gradation, undesirable expansion potential, or substandard strength characteristics may be designated by the consultant as unsuitable and may require blending with other soils to serve as a satisfactory fill material. Fill materials derived from benching operations should be dispersed throughout the fill area and blended with other approved material. Benching operations should not result in the benched material being placed only within a single equipment width away from the fill/bedrock contact. Oversized materials defined as rock, or other irreducible materials, with a maximum dimension greater than 12 inches, should not be buried or placed in fills unless the location of materials and disposal methods are specifically approved by the geotechnical consultant. Oversized material should be taken offsite, or placed in accordance with recommendations of the geotechnical consultant in areas designated as suitable for rock disposal. GSI anticipates that soils to be utilized as fill material for the subject project may contain some rock. Appropriately, the need for rock disposal may be necessary during grading operations on the site. From a geotechnical standpoint, the depth of any rocks, rock fills, or rock blankets, should be a sufficient distance from finish grade. This depth is generally the same as any overexcavation due to cut-fill transitions in hard rock areas, and generally facilitates the excavation of structural footings and substructures. Should deeper excavations be proposed (i.e., deepened footings, utility trenching, swimming pools, spas, etc.), the developer may consider increasing the hold-down depth of any rocky fills to be placed, as appropriate. In addition, some agencies/jurisdictions mandate a specific hold-down depth for oversize materials placed in fills. The hold-down depth, and potential to encounter oversize rock, both within fills, and occurring in cut or natural areas, would need to be disclosed to all interested/affected parties. Once approved by the governing agency, the hold-down depth for oversized rock (i.e., greater than 12 inches) in fills on this project is provided as 10 feet, unless specified differently in the text of this report. The governing agency may require that these materials need to be deeper, crushed, or reduced to less than 12 inches in maximum dimension, at their discretion. To facilitate future trenching, rock (or oversized material), should not be placed within the hold-down depth feetfrom finish grade, the range offoundation excavations, future utilities, or underground construction unless specifically approved by the governing agency, the geotechnical consultant, and/or the developer's representative. If import material is required for grading, representative samples of the materials to be utilized as compacted fill should be analyzed in the laboratory by the geotechnical consultant to evaluate it's physical properties and suitability for use onsite. Such testing should be performed three (3) days prior to importation. If any material other than that previously tested is encountered during grading, an appropriate analysis of this material should be conducted by the geotechnical consultant as soon as possible. BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 4 Approved fill material should be placed in areas prepared to receive fill in near horizontal layers, that when compacted, should not exceed about 6 to 8 inches in thickness. The geotechnical consultant may approve thick lifts if testing indicates the grading procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each layer should be spread evenly and blended to attain uniformity of material and moisture suitable for compaction. Fill layers at a moisture content less than optimum should be watered and mixed, and wet fill layers should be aerated by scarification, or should be blended with drier material. Moisture conditioning, blending, and mixing of the fill layer should continue until the fill materials have a uniform moisture content at, or above, optimum moisture. After each layer has been evenly spread, moisture conditioned, and mixed, it should be uniformly compacted to a minimum of 90 percent of the maximum density as evaluated by ASTM test designation D-1557, or as otherwise recommended by the geotechnical consultant. Compaction equipment should be adequately sized and should be specifically designed for soil compaction, or of proven reliability to efficiently achieve the specified degree of compaction . Where tests indicate that the density of any layer of fill, or portion thereof, is below the required relative compaction, or improper moisture is in evidence, the particular layer or portion shall be re-worked until the required density and/or moisture content has been attained. No additional fill shall be placed in an area until the last placed lift of fill has been tested and found to meet the density and moisture requirements, and is approved by the geotechnical consultant. In general, per the latest adopted version of the California Building Code (CBC), fill slopes should be designed and constructed at a gradient of 2:1 (h:v), or flatter. Compaction of slopes should be accomplished by over-building a minimum of 3 feet horizontally, and subsequently trimming back to the design slope configuration. Testing shall be performed as the fill is elevated to evaluate compaction as the fill core is being developed. Special efforts may be necessary to attain the specified compaction in the fill slope zone. Final slope shaping should be performed by trimming and removing loose materials with appropriate equipment. A final evaluation of fill slope compaction should be based on observation and/or testing of the finished slope face. Where compacted fill slopes are designed steeper than 2:1 (h:v), prior approval from the governing agency, specific material types, a higher minimum relative compaction, special reinforcement, and special grading procedures will be recommended. If an alternative to over-building and cutting back the compacted fill slopes is selected, then special effort should be made to achieve the required compaction in the outer 10 feet of each lift of fill by undertaking the following: 1. An extra piece of equipment consisting of a heavy, short-shanked sheepsfoot should be used to roll (horizontal) parallel to the slopes continuously as fill is placed. The sheepsfoot roller should also be used to roll perpendicular to the BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 5 slopes, and extend out over the slope to provide adequate compaction to the face of the slope. 2. Loose fill should not be spilled out over the face of the slope as each lift is compacted. Any loose fill spilled over a previously completed slope face should be trimmed off or be subject to re-rolling. 3. Field compaction tests will be made in the outer (horizontal) ±2 to ±8 feet of the slope at appropriate vertical intervals, subsequent to compaction operations. 4. After completion of the slope, the slope face should be shaped with a small tractor and then re-rolled with a sheepsfoot to achieve compaction to near the slope face. Subsequent to testing to evaluate compaction, the slopes should be grid-rolled to achieve compaction to the slope face. Final testing should be used to evaluate compaction after grid rolling. 5. Where testing indicates less than adequate compaction, the contractor will be responsible to rip, water, mix, and recompact the slope material as necessary to achieve compaction. Additional testing should be performed to evaluate compaction. SUBDRAIN INSTALLATION Subdrains should be installed in approved ground in accordance with the approximate alignment and details indicated by the geotechnical consultant. Subdrain locations or materials should not be changed or modified without approval of the geotechnical consultant. The geotechnical consultant may recommend and direct changes in subdrain line, grade, and drain material in the field, pending exposed conditions. The location of constructed subdrains, especially the outlets, should be recorded/surveyed by the project civil engineer. Drainage at the subdrain outlets should be provided by the project civil engineer. EXCAVATIONS Excavations and cut slopes should be examined during grading by the geotechnical consultant. If directed by the geotechnical consultant, further excavations or overexcavation and refilling of cut areas should be performed, and/or remedial grading of cut slopes should be performed. When fill-over-cut slopes are to be graded, unless otherwise approved, the cut portion of the slope should be observed by the geotechnical consultant prior to placement of materials for construction of the fill portion of the slope. The geotechnical consultant should observe all cut slopes, and should be notified by the contractor when excavation of cut slopes commence. BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 6 If, during the course of grading, unforeseen adverse or potentially adverse geologic conditions are encountered, the geotechnical consultant should investigate, evaluate, and make appropriate recommendations for mitigation of these conditions. The need for cut slope buttressing or stabilizing should be based on in-grading evaluation by the geotechnical consultant, whether anticipated or not. Unless otherwise specified in geotechnical and geological report(s), no cut slopes should be excavated higher or steeper than that allowed by the ordinances of controlling governmental agencies. Additionally, short-term stability of temporary cut slopes is the contractor's responsibility. Erosion control and drainage devices should be designed by the project civil engineer and should be constructed in compliance with the ordinances of the controlling governmental agencies, and/or in accordance with the recommendations of the geotechnical consultant. COMPLETION Observation, testing, and consultation by the geotechnical consultant should be conducted during the grading operations in order to state an opinion that all cut and fill areas are graded in accordance with the approved project specifications. After completion of grading, and after the geotechnical consultant has finished observations of the work, final reports should be submitted, and may be subject to review by the controlling governmental agencies. No further excavation or filling should be undertaken without prior notification of the geotechnical consultant or approved plans. All finished cut and fill slopes should be protected from erosion and/or be planted in accordance with the project specifications and/or as recommended by a landscape architect. Such protection and/or planning should be undertaken as soon as practical after completion of grading. PRELIMINARY OUTDOOR POOL/SPA DESIGN RECOMMENDATIONS The following preliminary recommendations are provided for consideration in pool/spa design and planning. Actual recommendations should be provided by a qualified geotechnical consultant, based on site specific geotechnical conditions, including a subsurface investigation, differential settlement potential, expansive and corrosive soil potential, proximity of the proposed pool/spa to any slopes with regard to slope creep and lateral fill extension, as well as slope setbacks per Code, and geometry of the proposed improvements. Recommendations for pools/spas and/or deck flatwork underlain by expansive soils, or for areas with differential settlement greater than ¼-inch over 40 feet horizontally, will be more onerous than the preliminary recommendations presented below. The 1 :1 (h:v) influence zone of any nearby retaining wall site structures should be delineated on the project civil drawings with the pool/spa. This 1 :1 (h:v) zone is defined as a plane up from the lower-most heel of the retaining structure, to the daylight grade of BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 7 the nearby building pad or slope. If pools/spas or associated pool/spa improvements are constructed within this zone, they should be re-positioned (horizontally or vertically) so that they are supported by earth materials that are outside or below this 1 : 1 plane. If this is not possible given the area of the building pad, the owner should consider eliminating these improvements or allow for increased potential for lateral/vertical deformations and associated distress that may render these improvements unusable in the future, unless they are periodically repaired and maintained. The conditions and recommendations presented herein should be disclosed to all interested/affected parties. General 1. The equivalent fluid pressure to be used for the pool/spa design should be 60 pounds per cubic foot (pcf) for pool/spa walls with level backfill, and 75 pcf for a 2:1 sloped backfill condition. In addition, backdrains should be provided behind pool/spa walls subjacent to slopes. 2. Passive earth pressure may be computed as an equivalent fluid having a density of 150 pcf, to a maximum lateral earth pressure of 1,000 pounds per square foot (psf). 3. An allowable coefficient of friction between soil and concrete of 0.30 may be used with the dead load forces. 4. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. 5. Where pools/spas are planned near structures, appropriate surcharge loads need to be incorporated into design and construction by the pool/spa designer. This includes, but is not limited to landscape berms, decorative walls, footings, built-in barbeques, utility poles, etc. 6. All pool/spa walls should be designed as "free standing" and be capable of supporting the water in the pool/spa without soil support. The shape of pool/spa in cross section and plan view may affect the performance of the pool, from a geotechnical standpoint. Pools and spas should also be designed in accordance with the latest adopted Code. Minimally, the bottoms of the pools/spas, should maintain a distance H/3, where His the height of the slope (in feet), from the slope face. This distance should not be less than 7 feet, nor need not be greater than 40 feet. 7. The soil beneath the pool/spa bottom should be uniformly moist with the same stiffness throughout. If a fill/cut transition occurs beneath the pool/spa bottom, the cut portion should be overexcavated to a minimum depth of 48 inches, and replaced with compacted fill, such that there is a uniform blanket that is a minimum of 48 inches below the pool/spa shell. If very low expansive soil is used for fill, the fill should be placed at a minimum of 95 percent relative compaction, at optimum moisture conditions. This requirement should be 90 percent relative compaction BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 8 at over optimum moisture if the pool/spa is constructed within or near expansive soils. The potential for grading and/or re-grading of the pool/spa bottom, and attendant potential for shoring and/or slot excavation, needs to be considered during all aspects of pool/spa planning, design, and construction. 8. If the pool/spa is founded entirely in compacted fill placed during rough grading, the deepest portion of the pool/spa should correspond with the thickest fill on the lot. 9. Hydrostatic pressure relief valves should be incorporated into the pool and spa designs. A pool/spa under-drain system is also recommended, with an appropriate outlet for discharge. 10. All fittings and pipe joints, particularly fittings in the side of the pool or spa, should be properly sealed to prevent water from leaking into the adjacent soils materials, and be fitted with slip or expandible joints between connections transecting varying soil conditions. 11 . An elastic expansion joint (flexible waterproof sealant) should be installed to prevent water from seeping into the soil at all deck joints. 12. A reinforced grade beam should be placed around skimmer inlets to provide support and mitigate cracking around the skimmer face. 13. In order to reduce unsightly cracking, deck slabs should minimally be 4 inches thick, and reinforced with No. 3 reinforcing bars at 18 inches on-center. All slab reinforcement should be supported to ensure proper mid-slab positioning during the placement of concrete. Wire mesh reinforcing is specifically not recommended. Deck slabs should not be tied to the pool/spa structure. Pre-moistening and/or pre-soaking of the slab subgrade is recommended, to a depth of 12 inches (optimum moisture content), or 18 inches (120 percent of the soil's optimum moisture content, or 3 percent over optimum moisture content, whichever is greater), for very low to low, and medium expansive soils, respectively. This moisture content should be maintained in the subgrade soils during concrete placement to promote uniform curing of the concrete and minimize the development of unsightly shrinkage cracks. Slab underlayment should consist of a 1-to 2-inch leveling course of sand (S.E.>30) and a minimum of 4 to 6 inches of Class 2 base compacted to 90 percent. Deck slabs within the H/3 zone, where H is the height of the slope (in feet), will have an increased potential for distress relative to other areas outside of the H/3 zone. If distress is undesirable, improvements, deck slabs or flatwork should not be constructed closer than H/3 or 7 feet (whichever is greater) from the slope face, in order to reduce, but not eliminate, this potential. 14. Pool/spa bottom or deck slabs should be founded entirely on competent bedrock, or properly compacted fill. Fill should be compacted to achieve a minimum 90 percent relative compaction, as discussed above. Prior to pouring concrete, BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 9 subgrade soils below the pool/spa decking should be throughly watered to achieve a moisture content that is at least 2 percent above optimum moisture content, to a depth of at least 18 inches below the bottom of slabs. This moisture content should be maintained in the subgrade soils during concrete placement to promote uniform curing of the concrete and minimize the development of unsightly shrinkage cracks. 15. In order to reduce unsightly cracking, the outer edges of pool/spa decking to be bordered by landscaping, and the edges immediately adjacent to the pool/spa, should be underlain by an 8-inch wide concrete cutoff shoulder (thickened edge) extending to a depth of at least 12 inches below the bottoms of the slabs to mitigate excessive infiltration of water under the pool/spa deck. These thickened edges should be reinforced with two No. 4 bars, one at the top and one at the bottom. Deck slabs may be minimally reinforced with No. 3 reinforcing bars placed at 18 inches on-center, in both directions. All slab reinforcement should be supported on chairs to ensure proper mid-slab positioning during the placement of concrete. 16. Surface and shrinkage cracking of the finish slab may be reduced if a low slump and water-cement ratio are maintained during concrete placement. Concrete utilized should have a minimum compressive strength of 4,000 psi. Excessive water added to concrete prior to placement is likely to cause shrinkage cracking, and should be avoided. Some concrete shrinkage cracking, however, is unavoidable. 17. Joint and sawcut locations for the pool/spa deck should be determined by the design engineer and/or contractor. However, spacings should not exceed 6 feet on center. 18. Considering the nature of the onsite earth materials, it should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls/backcuts at the angle of repose (typically 25 to 45 degrees), should be anticipated. All excavations should be observed by a representative of the geotechnical consultant, including the project geologist and/or geotechnical engineer, prior to workers entering the excavation or trench, and minimally conform to Cal/OSHA ("Type C" soils may be assumed), state, and local safety codes. Should adverse conditions exist, appropriate recommendations should be offered at that time by the geotechnical consultant. GSI does not consult in the area of safety engineering and the safety of the construction crew is the responsibility of the pool/spa builder. 19. It is imperative that adequate provisions for surface drainage are incorporated into the overall improvement scheme. Ponding water, ground saturation and flow over slope faces, are all situations which must be avoided to enhance long term performance of the pool/spa and associated improvements, and reduce the likelihood of distress. 20. Regardless of the methods employed, once the pool/spa is filled with water, should it be emptied, there exists some potential that if emptied, significant distress may BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 10 occur. Accordingly, once filled, the pool/spa should not be emptied unless evaluated by the geotechnical consultant and the pool/spa builder. 21. For pools/spas built within (all or part) of the Code setback and/or geotechnical setback, as indicated in the site geotechnical documents, special foundations are recommended to mitigate the affects of creep, lateral fill extension, expansive soils and settlement on the proposed pool/spa. Most municipalities or County reviewers do not consider these effects in pool/spa plan approvals. As such, where pools/spas are proposed on 20 feet or more of fill, medium or highly expansive soils, or rock fill with limited "cap soils" and built within Code setbacks, or within the influence of the creep zone, or lateral fill extension, the following should be considered during design and construction: OPTION A: Shallow foundations with or without overexcavation of the pool/spa "shell," such that the pool/spa is surrounded by 5 feet of very low to low expansive soils (without irreducible particles greater that 6 inches), and the pool/spa walls closer to the slope(s) are designed to be free standing. GSI recommends a pool/spa under-drain or blanket system (see attached Typical Pool/Spa Detail). The pool/spa builders and owner in this optional construction technique should be generally satisfied with pool/spa performance under this scenario; however, some settlement, tilting, cracking, and leakage of the pool/spa is likely over the life of the project. OPTION B: Pier supported pool/spa foundations with or without overexcavation of the pool/spa shell such that the pool/spa is surrounded by 5 feet of very low to low expansive soils (without irreducible particles greater than 6 inches), and the pool/spa walls closer to the slope(s) are designed to be free standing. The need for a pool/spa under-drain system may be installed for leak detection purposes. Piers that support the pool/spa should be a minimum of 12 inches in diameter and at a spacing to provide vertical and lateral support of the pool/spa, in accordance with the pool/spa designers recommendations current applicable Codes. The pool/spa builder and owner in this second scenario construction technique should be more satisfied with pool/spa performance. This construction will reduce settlement and creep effects on the pool/spa; however, it will not eliminate these potentials, nor make the pool/spa "leak-free." 22. The temperature of the water lines for spas and pools may affect the corrosion properties of site soils, thus, a corrosion specialist should be retained to review all spa and pool plans, and provide mitigative recommendations, as warranted. Concrete mix design should be reviewed by a qualified corrosion consultant and materials engineer. BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 11 23. All pool/spa utility trenches should be compacted to 90 percent of the laboratory standard, under the full-time observation and testing of a qualified geotechnical consultant. Utility trench bottoms should be sloped away from the primary structure on the property (typically the residence). 24. Pool and spa utility lines should not cross the primary structure's utility lines (i.e., not stacked, or sharing of trenches, etc.). 25. The pool/spa or associated utilities should not intercept, interrupt, or otherwise adversely impact any area drain, roof drain, or other drainage conveyances. If it is necessary to modify, move, or disrupt existing area drains, subdrains, or tightlines, then the design civil engineer should be consulted, and mitigative measures provided. Such measures should be further reviewed and approved by the geotechnical consultant, prior to proceeding with any further construction. 26. The geotechnical consultant should review and approve all aspects of pool/spa and flatwork design prior to construction. A design civil engineer should review all aspects of such design, including drainage and setback conditions. Prior to acceptance of the pool/spa construction, the project builder, geotechnical consultant and civil designer should evaluate the performance of the area drains and other site drainage pipes, following pool/spa construction. 27. All aspects of construction should be reviewed and approved by the geotechnical consultant, including during excavation, prior to the placement of any additional fill, prior to the placement of any reinforcement or pouring of any concrete. 28. Any changes in design or location of the pool/spa should be reviewed and approved by the geotechnical and design civil engineer prior to construction. Field adjustments should not be allowed until written approval of the proposed field changes are obtained from the geotechnical and design civil engineer. 29. Disclosure should be made to all builders, contractors, and any interested/affected parties, that pools/spas built within about 15 feet of the top of a slope, and/or H/3, where H is the height of the slope (in feet), will experience some movement or tilting. While the pool/spa shell or coping may not necessarily crack, the levelness of the pool/spa will likely tilt toward the slope, and may not be esthetically pleasing. The same is true with decking, flatwork and other improvements in this zone. 30. Failure to adhere to the above recommendations will significantly increase the potential for distress to the pool/spa, flatwork, etc. 31. Local seismicity and/or the design earthquake will cause some distress to the pool/spa and decking or flatwork, possibly including total functional and economic loss. BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 12 32. The information and recommendations discussed above should be provided to any contractors and/or subcontractors, or interested/affected parties, etc., that may perform or may be affected by such work. JOB SAFETY General At GSI, getting the job done safely is of primary concern. The following is the company's safety considerations for use by all employees on multi-employer construction sites. On-ground personnel are at highest risk of injury, and possible fatality, on grading and construction projects. GSI recognizes that construction activities will vary on each site, and that site safety is the prime responsibility of the contractor; however, everyone must be safety conscious and responsible at all times. To achieve our goal of avoiding accidents, cooperation between the client, the contractor, and GSI personnel must be maintained. In an effort to minimize risks associated with geotechnical testing and observation, the following precautions are to be implemented for the safety of field personnel on grading and construction projects: Safety Meetings: GSI field personnel are directed to attend contractor's regularly scheduled and documented safety meetings. Safety Vests: Safety vests are provided for, and are to be worn by GSI personnel, at all times, when they are working in the field. Safety Flags: Two safety flags are provided to GSI field technicians; one is to be affixed to the vehicle when on site, the other is to be placed atop the spoil pile on all test pits. Flashing Lights: All vehicles stationary in the grading area shall use rotating or flashing amber beacons, or strobe lights, on the vehicle during all field testing. While operating a vehicle in the grading area, the emergency flasher on the vehicle shall be activated. In the event that the contractor's representative observes any of our personnel not following the above, we request that it be brought to the attention of our office. Test Pits Location, Orientation, and Clearance The technician is responsible for selecting test pit locations. A primary concern should be the technician's safety. Efforts will be made to coordinate locations with the grading contractor's authorized representative, and to select locations following or behind the established traffic pattern, preferably outside of current traffic. The contractor's authorized representative (supervisor, grade checker, dump man, operator, etc.) should direct BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 13 excavation of the pit and safety during the test period. Of paramount concern should be the soil technician's safety, and obtaining enough tests to represent the fill. Test pits should be excavated so that the spoil pile is placed away from oncoming traffic, whenever possible. The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This necessitates the fill be maintained in a driveable condition. Alternatively, the contractor may wish to park a piece of equipment in front of the test holes, particularly in small fill areas or those with limited access. A zone of non-encroachment should be established for all test pits. No grading equipment should enter this zone during the testing procedure. The zone should extend approximately 50 feet outward from the center of the test pit. This zone is established for safety and to avoid excessive ground vibration, which typically decreases test results. When taking slope tests, the technician should park the vehicle directly above or below the test location. If this is not possible, a prominent flag should be placed at the top of the slope. The contractor's representative should effectively keep all equipment at a safe operational distance (e.g., 50 feet) away from the slope during this testing . The technician is directed to withdraw from the active portion of the fill as soon as possible following testing. The technician's vehicle should be parked at the perimeter of the fill in a highly visible location, well away from the equipment traffic pattern. The contractor should inform our personnel of all changes to haul roads, cut and fill areas or other factors that may affect site access and site safety. In the event that the technician's safety is jeopardized or compromised as a result of the contractor's failure to comply with any of the above, the technician is required, by company policy, to immediately withdraw and notify his/her supervisor. The grading contractor's representative will be contacted in an effort to affect a solution. However, in the interim, no further testing will be performed until the situation is rectified. Any fill placed can be considered unacceptable and subject to reprocessing, recompaction, or removal. In the event that the soil technician does not comply with the above or other established safety guidelines, we request that the contractor bring this to the technician's attention and notify this office. Effective communication and coordination between the contractor's representative and the soil technician is strongly encouraged in order to implement the above safety plan. Trench and Vertical Excavation It is the contractor's responsibility to provide safe access into trenches where compaction testing is needed. Our personnel are directed not to enter any excavation or vertical cut which: 1) is 5 feet or deeper unless shored or laid back; 2) displays any evidence of instability, has any loose rock or other debris which could fall into the trench; or 3) displays any other evidence of any unsafe conditions regardless of depth. BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 14 All trench excavations or vertical cuts in excess of 5 feet deep, which any person enters, should be shored or laid back. Trench access should be provided in accordance with Cal/OSHA and/or state and local standards. Our personnel are directed not to enter any trench by being lowered or "riding down" on the equipment. If the contractor fails to provide safe access to trenches for compaction testing, our company policy requires that the soil technician withdraw and notify his/her supervisor. The contractor's representative will be contacted in an effort to affect a solution. All backfill not tested due to safety concerns or other reasons could be subject to reprocessing and/or removal. If GSI personnel become aware of anyone working beneath an unsafe trench wall or vertical excavation, we have a legal obligation to put the contractor and owner/developer on notice to immediately correct the situation. If corrective steps are not taken, GSI then has an obligation to notify Cal/OSHA and/or the proper controlling authorities. BNR Investments File:e:\wp12\7500\7535a.gue GeoSoils, Inc. Appendix F Page 15 TYPE A ------------, ---------- Natural grade ~ Proposed grade , . Colluvium and alluvium (remo /. / ' -\ ,...... ....... , .... ·. _....,.,,.......,, ,,' -~~~ ' -<- \ 1/ \\ :-.'' / Typical benching Bedrock or / 1/ approved /,Y/, native materia See Alternate Details Selection of alternate subdrain details, location, and extent of subdrains should be evaluated by the geotechnical consultant during grading. c. CANYON SUBDRAIN DETAIL Plate F-1 6-inch minimum ""/ / 6inc minim 6-inch minimum 0 " =---( '--✓->-:::--\ ' '-- 6-inch minimum A-1 Filter material= Minimum volume of 9 cubic feet per lineal foot of pipe, Perforated pipe: 6-inch-diameter ABS or PVC pipe or approved substitute with minimum 8 perforations (¼-inch diameter) per lineal foot in bottom half of pipe (ASTM D-2751, SDR-35, or ASTM D-1527, Schd. 40). For continuous run in excess of 500 feet, use 8-inch-diameter pipe (ASTM D-3034, SDR-35, or ASTM D-1785, Schd. 40). 8-1 FILTER MATERIAL Sieve Size 1 inch ¾inch ¾ inch No.4 No. 8 No.30 No.50 No.200 Percent Passing 100 90-100 40-100 25-40 18-33 5-15 0-7 0-3 AL TERNA TE 1= PERFORATED PIPE AND FIL TEA MATERIAL \~ 6-inch minimum ~\ \ ""I I • ~-_,._I / '--~-~nch mr11mum --- 1 e-inch minimum ----------Fitter fabric 0,Y/ 6-inch minimum A-2 Gravel Material= 9 cubic feet per lineal foot. Perforated Pipe= See Alternate 1 Gravel= Clean ¾-inch rock or approved substitute. Filter Fabric= Mirafi 140 or approved substitute. ALTERNATE 2: PERFORATED PIPE, GRAVEL, AND FILTER FABRIC c. CANYON SUBDRAIN ALTERNATE DETAILS Plate F-2 Proposed grade~ --__ ,--------Previously placed, temporary compacted fill for drainage only ------- Proposed additional compacted fill Exiati~ compacted fill+~;~~:; ffi$'±1ft4<?: ·•· ·· ... ¾ ·: .... ::: ... ·/·. . . . . . . .. I~ mater1·a1 c··t . . . ':);.>:::::::•· , . ·• : · ... : · .. ·: ·.· • , ,, .... :· .. , .. o. be• remov 0-\V-V\\\:(V\%??)i'~<,'\\\:(\'i\\;(\~. ~0~y\\\'~ .. ·. ed) To be remo Bedrock or a additional c;ed before placi~ native materia\'proved mpacted fill c. REMOVAL ADJACENT TO EXISTING FILL ADJOINING CANYON FILL DETAIL Plate F-4 Natural grade Proposed pad grade ··. . · ..... ·· __ l_ ~··~·---~--- CUT LOT OR MATERIAL-TYPE TRANSITION Natural grade . ···-: . ..... :·: ..... '·~ ·. . . . . . . . :, : : . · .. : . ,,,.. : . ·:. · .. :· :,;_-\; . ·3-to '7-foot' minimum• . .. _ · · ~ \\:: overexcavate and recompact . b\e ~e.~ ....,....,.,.,....,.........,.,......,,.......,...ii'),: per text of report -~ ~~ · · \ ,, • Deeper overexcavation may be Typical benching ( 4-foot minimum) Bedrock or approved native material recommended by the geotechnical consultant in steep cut-fill transition areas, such that the underlying topography is no steeper than 3=1 (H=V) CUT-FILL LOT (DAYLIGHT TRANSITION) c. TRANSITION LOT DETAILS Plate F-12 MAP VIEW NOTTO SCALE Concrete cut-off wall SEE NOT._r_S __________ j B I Top of elope ~ 2-inch-thick sand layer Gravity-flow, nonperforated subdrain I=== pipe (tranoverael Toe of slope 4 I 15feet Pool 4-inch perforated subdrain pipe (longitudinal) Coping A' 4-inch perforated subdrain pipe (transverse) Pool Direction of drainage B' CROSS SECTION VIEW Coping NOTTO SCALE SEE NOTES Pool encapsulated in 5-foot thickness of sand ----, 6-inch-thick gravel layer B NOTES= r H Gravity-flow nonperforated subdrain pipe 4-inch perforated subdrain pipe Coping I B' --1 1 steet 2-inch-thick sand layer Vapor retarder Perforated subdrain pipe 1. 6-inch-thick, clean gravel(¾ to 1½ inch) sub-base encapsulated in Mirafi 140N or equivalent, underlain by a 15-mil vapor retarder, with 4-inch-diameter perforated pipe longitudinal connected to 4-inch-diameter perforated pipe transverse. Connect transverse pipe to 4-inch-diameter nonperforated pipe at low point and outlet or to sump pump area. 2. Pools on fills thicker than 20 feet should be constructed on deep foundations; otherwise, distress (tilting, cracking, etc.) should be expected. 3. Design does not apply to infinity-edge pools/spas. c. TYPICAL POOL/SPA DETAIL Plate F-17 SIDE VIEW Test pit TOP VIEW Flag Flag Spoil pile Test pit Light Vehicle -----50feet-------------50feet----- a------------------lUUfee,r------------------1- c. TEST PIT SAFETY DIAGRAM Plate F-20 M~~t•:; •0, __--(!/ 11 K" i ' , ,ff.-~ ~ ~ ~l / L N GS/ LEGEND B • • ! A ~ ' ' i ro § ~ 1....., ,., __ BUILDING "8"--------< ·ol ...... .,_ ... -------BUILDING "A"--------< ...... -- A' ,, f-~ 'L..,,.....,. ~-Y· II II t_- ri>,ij· -------~~---.;;;;-~ Qst _,,,,,.,,,. II __________ / ________________ ~~ ~q~t===r~~~~ • • ! 70 g_ ~ ~ IJISTAHCE(FITT) NIU'E -- TDm78f B' • ' ----I ' L_J I--BUILDING "E" ----j 1---------BUILDING "C"--------1 f-----BUILDING IE'T:::s'IMUS • . • If.I..,.._ -·•·------"½..=,..,, ~ . ------., I 11 . f-~ . • ' • t-1 -·· j . ----;;::.:,------•-----------~;-~\ ,__ ,. •• ----------------~-------------• _____ ;: :: ' Af 70 I Af Af ------------- Qst -a,-,------------__.!...--±"?_r_r_r,,, Qst -· = N38'W ~ DISTMr:tc(fE£1;) N3'E ~ --§ ~.;, Qst ~ ALL LOCATIONS ARE APPROXMIATE 111111 _____ ,..,,.,.lf,:,flllf~ -•""•llouldllOlbt--•~M -dtf>lcfionoldolffn. Af -MmaALFUPU.ctDIINDiR1H£M\O'fS8£1(19'1) Qal -""'""""'""""" GEOLOGIC Qcol-""'""""'"""""' Qst -W41ZHHARYSIREMl1EMACE:DEPOSl1S CROSS SECTIONS A·A' & 8-8' -?--~=OOH rs GEOI.OGJC CCWTACT, WEREl Plate2 w.o. 7535-A-SC DATE: 02/19 SCALE: 1"=10'