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HomeMy WebLinkAboutCT 13-01; Buena Vista 11; Geotechnical CT 13-01; 2013-03-13PRELIMINARY GEOTECHNICAL EVALUATION BUENA VISTA It^tfBDIVlSION, APNs 156-200-01, <02, AND -15 CITY OF CARLSBAD, SAN DIEGO COUI<^TY^ CALIFORNIA KRAEMER LANO, INC. 101 S. KRAEMER BOULEVARD, SUITE 136 PLACENTIA, CALIFORNIA 92870 " W.O. 6524-A-SC MARCH 13, 2013 Geotechnical • Geologic • Coastal • Environmental 5741 Palmer Way • Carlsbad, California 92010 • (760)438-3155 • FAX (760) 931-0915 • www.geosoilsinc.com March 13, 2013 W.O. 6524-A-SC Kraemer Land, Inc. 101 S. Kraenner Boulevard, Suite 136 Placentia, California 92870 Attention: Mr. Matthew Ferree Subject: Preliminary Geotechnical Evaluation, Buena Vista 11 Subdivision, APNs 156-200-01,02, and 15, Cityof Carlsbad, San Diego County, California Dear Mr. Ferree: In accordance with your request and authorization, GeoSoils, Inc. (GSI) is pleased to present the results of our preliininary geotechnical evaluation of the subject site. The purpose of our study was to evaluate the site geologic and geotechnical conditions in order to develop preliminary recommendations for earthwork and the design of foundations, walls, and pavements as they relate to the proposed 11-lot residential subdivision at the property. EXECUTIVE SUMMARY Based upon our field exploration, geologic, and geotechnical engineering analysis, the proposed development appears feasible from a soils engineering and geologic viewpoint, provided that the recommendations presented in the text of this report are properly incorporated into the design and construction ofthe project. The most significant elements of our study are summarized below: • In general, the site may be characterized as being mantled by relatively thin sections of localized undocumented artificial fill and colluvium. These earth materials are in turn underlain by Quaternary-age paralic deposits which are considered formational earth materials. The upper ±1 foot to ±4V2 feet of the paralic deposits are weathered in-place. • Due to their relatively low density, lack of uniformity, and porous nature, all undocumented fill, Quaternary-age colluvium, and surficial weathered paralic deposits are considered potentially compressible and unsuitable forthe support of settlement-sensitive improvements (i.e., residential foundations, concrete slab-on-grade floors, site walls, underground utilities, roadways, exterior hardscape, etc.) and/or engineered fill in their existing state. Based on the available data, the thickness of potentially compressible soils across the site is anticipated to vary between approximately 1 foot and 6V2 feet. However, localized thicker sections of unsuitable soils cannot be precluded and should be anticipated. Conversely, the underlying unweathered paralic deposits are considered suitable forthe support of settlement-sensitive improvements and engineered fill. It should be noted that the 2010 California Building Code ([2010 CBC], California Building Standards Commission [CBSC], 2010) 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 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 (horizontahvertical [h:v]) projection up from the bottom, outboard edge of the remedial grading excavation at the subdivision boundary would be affected by perimeter conditions. Qn a preliminary basis, any planned settlement-sensitive improvements located within approximately 1 foot and 6V2 feet from the subdivision boundary would require deepened foundations or additional reinforcement by means of ground improvement or specific structural design. Otherwise these improvements may be subject to distress and a reduced serviceable lifespan. This will also require proper disclosure to any owners and all interested/affected parties should this condition exist at the conclusion of grading. Laboratory testing, including expansion index (E.I.) and Atterberg Limits, performed on samples ofthe onsite soils, indicates expansion indices ranging between <5 and 23. Thus, on a preliminary basis, the expansion potential ofthe onsite soils ranges from very low to low. Atterberg limits testing performed on the finer grained soil sample (i.e., sample with the higher E.I.) indicates a plasticity index (P.l.) of 18. As such, some ofthe site soils are considered detrimentally expansive as defined in Section 1803.5.2 of the 2010 CBC. Based on the available subsurface data, detrimentally expansive soils are believed to be confined tothe lower site elevations at the easterly portion of the site. On a preliminary basis, residential building foundations within the influence of expansive soils should be designed and constructed in accordance with Sections 1808.6.1 or 1808.6.2 ofthe 2010 CBC. However, it is possible that through selective grading or earthwork mitigation techniques, soils within the influence of the residential foundation may be non-detrimentally expansive at the conclusion of grading and possibly allow for the use of conventional foundations and slab-on-grade floors. A 1:1 (h:v) setback up from the heel of all segmental retaining wall foundations and/or the heel ofthe geogrid-reinforced zone should be incorporated into project planning and design. Kraemer Land, Inc. _ W.O. 6524-A-SC File:e:\wp12\6400\6476a.pge GCOSoilS, IllC. Page Two Corrosion testing performed on a representative sample ofthe onsite soils indicates site soils are moderately alkaline with respect to soil acidity/alkalinity, corrosive to exposed buried metals when saturated, present negligible sulfate exposure to concrete and are below action levels for chloride exposure. Neither the regional groundwater table nor perched water was encountered during our subsurface studies to the depth explored. As such, groundwater is not anticipated to significantly affect the planned improvements. Perched water may occur in the future along zones of contrasting permeability and/or density. This potential should be disclosed to all interested/affected parties. Our evaluation indicates there are no known active faults crossing the site and the natural slope upon which the site is located has very low susceptibility to deep-seated landslides. Owing to the depth to groundwater and the dense nature of the paralic deposits, the potential for the site to be adversely affected by liquefaction/lateral spreading is considered very low. Site soils are considered erosive. Thus, properly designed and maintained site drainage is necessary in reducing erosion damage to the planned improvements. 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 structure will be repairable in the event of the design seismic event. This potential should be disclosed to any owners and all interested/affected parties. Additional adverse geologic features that would preclude project feasibility were not encountered, based on the available data. The recommendations presented in this report should be incorporated into the design and construction considerations of the project. Kraemer Land, Inc. _ W.O. 6524-A-SC File:e:\wp12\6500\6524a.pge GcoSoils, ItlC. Page Three The opportunity to be of service is sincerely appreciated. If you should have any questions, please do not hesitate to contact our office. Respectfully submitted^ GeoSoils, Inc. [ Engineering Geologist, Ryan B. Boehmer Staff Geologist RBB/JPF/DWS/jh Distribution: (3) Addressee David W. Skelly Civil Engineer, RCE 47i Kraemer Land, Inc. File:e:\wp12\6500\6524a.pge GeoSoils, Inc. W.O. 6524-A-SC Page Four TABLE OF CONTENTS SCOPE OF SERVICES 1 SITE DESCRIPTION AND PROPOSED DEVELOPMENT 1 FIELD STUDIES 3 REGIONAL GEOLOGY 3 SITE GEOLOGIC UNITS 4 General 4 Undocumented Artificial Fill (Map Symbol - Afu) 4 Quaternary Colluvium (Not Mapped) 4 Quaternary Paralic Deposits (Map Symbol - Qp) 4 Structural Geology 5 GROUNDWATER 5 ROCK HARDNESS/EXCAVATION DIFFICULTY 6 GEOLOGIC HAZARDS EVALUATION 6 Mass Wasting/Landslide Susceptibility 6 FAULTING AND REGIONAL SEISMICITY 7 Regional Faults 7 Local Faulting 7 Surface Rupture 7 Seismicity 7 Seismic Shaking Parameters 8 SECONDARY SEISMIC HAZARDS 10 Liquefaction/Lateral Spreading 10 Seismic Densification 10 Summary 11 Other Geologic/Secondary Seismic Hazards 11 SLOPE STABILITY 11 LABORATORY TESTING 11 Classification 12 Moisture-Density Relations 12 Expansion Index 12 Atterberg Limits 12 Grain Size Distribution 13 GeoSoils, Inc. Direct Shear 13 Saturated Resistivity, pH, and Soluble Sulfates, and Chlorides 13 Corrosion Summary 13 PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS 14 EARTHWORK CONSTRUCTION RECOMMENDATIONS 16 General 16 Site Preparation 17 Removal and Recompaction of Potentially Compressible Earth Materials 17 Perimeter Conditions 18 Fill Placement 18 Overexcavation 18 Expansive Soil Mitigation/Selective Grading 19 Import Soils 19 Graded Slope Construction 19 Temporary Slopes 20 Excavation Observation and Monitoring (All Excavations) 20 Observation 21 Earthwork Balance (Shrinkage/Bulking) 21 PRELIMINARY RECOMMENDATIONS - FOUNDATIONS 22 General 22 Preliminary Foundation Design 22 PRELIMINARY FOUNDATION CONSTRUCTION RECOMMENDATIONS 23 Conventional Foundation and Slab-On-Grade Floor Systems 23 Post-Tensioned Foundations 24 Soil Moisture 25 Perimeter Cut-Off Walls 26 Post-Tensioned Foundation Design 26 Soil Support Parameters 26 Foundation Settlement 27 SOIL MOISTURE TRANSMISSION CONSIDERATIONS 28 WALL DESIGN PARAMETERS CONSIDERING EXPANSIVE SOILS 30 Conventional Retaining Walls 30 Restrained Walls 30 Cantilevered Walls 30 Seismic Surcharge 31 Retaining Wall Backfill and Drainage 32 Wall/Retaining Wall Footing Transitions 36 Kraemer Land, Inc , Table of Contents File:e:\wp12\6500\6524a.pge GcoSoilS, ItlC. Page ii PRELIMINARY SEGMENTAL RETAINING WALL PARAMETERS 36 Guidelines for Segmental Retaining Wall Construction 37 Foundation 38 Backfill 39 Wall Back Drains 40 Materials and Wall Construction 40 Structural Setbacks from Existing and Proposed Segmental Retaining Walls. . 41 Review of Segmental Retaining Wall Plans and Structural Calculations 41 Soil Expansion 41 Other Considerations 42 Additional Testing 42 TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS AND EXPANSIVE SOILS 43 Expansive Soils and Slope Creep 43 Top of Slope Walls/Fences 43 EXPANSIVE SOILS, DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS 44 PRELIMINARY ASPHALTIC CONCRETE PAVEMENT DESIGN RECOMMENDATIONS.46 General 46 PAVEMENT GRADING RECOMMENDATIONS 47 General 47 Subgrade 47 Aggregate Base 48 Paving 48 Drainage 48 PCC Cross Gutters 48 Additional Considerations 49 ONSITE INFILTRATION-RUNOFF RETENTION SYSTEMS 49 General 49 Plan Specific 52 DEVELOPMENT CRITERIA 53 Slope Deformation 53 Slope Maintenance and Planting 54 Drainage 54 Toe of Slope Drains/Toe Drains 55 Erosion Control 58 Landscape Maintenance 58 Gutters and Downspouts 58 Subsurface and Surface Water 58 Site Improvements 59 Tile Flooring 59 Kraemer Land, lnc _ Table of Contents File:e:\wp12\6500\6524a.pge GeoSoilS, IttC. Page ill Additional Grading 59 Footing Trench Excavation 59 Trenching/Temporary Construction Backcuts 60 Utility Trench Backfill 60 SUMMARYOF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING 60 OTHER DESIGN PROFESSIONALS/CONSULTANTS 61 PLAN REVIEW 62 LIMITATIONS 62 FIGURES: Figure 1 - Site Location Map 2 Detail 1 - Typical Retaining Wall Backfill and Drainage Detail 33 Detail 2 - Retaining Wall Backfill and Subdrain Detail Geotextile Drain 34 Detail 3 - Retaining Wall and Subdrain Detail Clean Sand Backfill 35 Detail 4 - Schematic Toe Drain Detail 56 Detail 5 - Subdrain Along Retaining Wall Detail 57 ATTACHMENTS: Plate 1 - Geotechnical Map Rear of Text Appendix A - References Rear of Text Appendix B - Hand Auger Boring Logs Rear of Text Appendix C - Seismicity Rear of Text Appendix D - Laboratory Data Rear of Text Appendix E - General Earthwork and Grading Guidelines Rear of Text Kraemer Land, Inc Flle:e:\wp12\6500\6524a.pge GeoSoils, Inc. Table of Contents Page iv PREUMINARY GEOTECHNICAL EVALUATION BUENA VISTA 11 SUBDIVISION, APN 156-200-01, -02, AND -15 CITY OF CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA SCOPE OF SERVICES The scope of our services has included the following: 1. Review of readily available published literature, aerial photographs, and maps ofthe vicinity (see Appendix A), including proprietary in-house geologic/geotechnical reports for other nearby sites. 2. Site reconnaissance mapping and the excavation of five (5) exploratory test pits and two (2) hand-auger borings to evaluate the soil/bedrock profiles, sample representative earth materials, and delineate the horizontal and vertical extent of earth material units (see Appendix B). 3. General areal geologic and seismic hazards evaluation (see Appendix C). 4. Appropriate laboratory testing of relatively undisturbed and representative bulk soil samples collected during our geologic mapping and subsurface exploration program (see Appendix D). 5. Analysis of field and laboratory data relative to the proposed development. 6. Appropriate engineering and geologic analyses of data collected, and the preparation of this summary report and accompaniments. SITE DESCRIPTION AND PROPOSED DEVELOPMENT The subject site consists of a nearly trapezoidal-shaped property located at the southwest corner of Buena Vista Way and Valley Street in the City of Carlsbad, San Diego County, California (see Figure 1, Site Location Map). Physical addresses for the subject property include 1655 and 1677 Buena Vista Way, Carlsbad, California 92008. The latitude and longitude ofthe approximate center ofthe site is 33.1680° North and 117.3370° West. The property is bounded by Valley Street to the east, by Buena Vista Way to the north, by existing residential development to the south, and by an abandoned, concrete-lined City of Carlsbad water reservoir site to the west. The abandoned municipal reservoir on the adjacent, westerly site is empty. According to the preliminary tentative map prepared by Lundstrom Engineering and Surveying, Inc. ([LE&S], 2013), site elevations vary between approximately 156 to 180 feet Mean Sea Level (MSL) for an overall relief of approximately 24 feet. In general, the site slopes to the northeast at a gentle gradient (approximately 7:1 [horizontahvertical {h:v}]) or flatter. Surface drainage appears to be controlled by sheet flow runoff, primarily directed in a easterly/northeasterly direction toward a minor depression near the easterly margin of the site. From this point, it appears that surface runoff would flow offsite to the south. GeoSoils, Inc. Base Map: TOPO!® ©2003 National Geographic, U.S.G.S San Luis Rey Quadrangle, California - San Diego Co., 7.5 Minute, dated 1997, current, 1999. . Bu«n» VIM* WV*, aumVtMaWty SITE a v WOT TO SCALE Base Map: Google Maps, Copyright 2013 Google, Map Data Copyright 2013 Google This map Is copyrighted by Google 2013. il is unlawful to copy or reproduce ail or any part thereof, whether for personal use or resale, without permission. All rights reserved. CreoSoUst Inc. W.O. 6524'A-SC W.O. 6524'A-SC SITE LOCATION MAP IM Figure 1 Based on our review of LE&S(2013), GSI understands that proposed development includes preparing the site for the construction of 11 one- to two-story single-family residences and associated underground utilities, a cul-de-sac street, retaining walls, and Portland Cement Concrete (PCC) hardscape improvements. LE&S (2013) indicates that cut and fill grading techniques will be necessary to achieve the design grades with maximum planned cuts and fills on the order of ±14 feet and 9 feet, respectively. LE&S (2013) also indicates planned 2:1 (h:v) cut and fill slopes on the order of ±10 feet and ±3 feet, respectively. LE&S (2013) shows that retaining walls will be constructed along a portion ofthe southerly subdivision boundary, along the side-yards of Lots 6 and 11, and in the rear-yards of Lots 1 through 5. The maximum height of retained earth will be approximately 5 feet. Based on communication with an LE&S representative, GSI understands that the retaining walls will be of the segmental block variety. GSI understands that the proposed residential structures will consist of wood framing with typical concrete foundations, including slab-on-grade floors. Building loads are currently unknown but assumed to be typical for this type of relatively light residential construction. Sewage disposal will be tied into the municipal system. FIELD STUDIES Site-specific field studies were conducted by GSI on February 25, 2013, and consisted of reconnaissance geologic mapping, excavating five exploratory test pits, and advancing two hand-auger borings. The test pits and borings were logged by a representative of this office who collected representative bulk and undisturbed soil samples for appropriate laboratory testing. The logs of the test pits and borings are presented in Appendix B. Site geology and the location of the test pits and borings are presented on the Geotechnical Map (see Plate 1), which uses LE&S (2013) as a base. REGIONAL GEOLOGY The subject property lies within the coastal plains physiographic region ofthe Peninsular Ranges Geomorphic Province of southern California. This region consists of dissected, mesa-like terraces that transition inland to rolling hills. The encompassing Peninsular Ranges Geomorphic Province is characterized as elongated mountain ranges and valleys thattrend northwesterly (Norris and Webb, 1990). This geomorphic province extends from the base ofthe east-west aligned Santa Monica - San Gabriel Mountains, and continues south into Baja California. 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. In the Southern California region, deposition occurred during the Cretaceous Period and Cenozoic Era in the continental margin of a forearc basin. Sediments, derived from Cretaceous-age plutonic rocks and Jurassic-age volcanic rocks, were deposited during the Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13, 2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 3 Tertiary Period (Eocene-age) into the narrow, steep, coastal plain and continental margin ofthe 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 (currently termed "paralic 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. Regional geologic mapping by Kennedy and Tan (2005) indicate the site is underlain by Quaternary-age old paralic deposits (previously termed "terrace deposits"), which are considered formational earth materials at the site. SITE GEOLOGIC UNITS General The earth material units that were observed and/or encountered at the subject site consist of localized undocumented artificial fill. Quaternary-age colluvium, and weathered and unweathered Quaternary-age paralic deposits. 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. Undocumented Artificial Fill (Map Symbol - Afu) Undocumented artificial fill was not encountered in any of the test pits nor borings, but is believed to locally exist around some the existing structures. The fill likely consists of sand, silt, and clay mixtures generated from the natural onsite earth materials and may range in thickness from approximately 1 foot to 4 feet, but may be thicker locally. All undocumented fill is potentially compressible in its existing state and should not be relied upon for the support of settlement-sensitive improvements and/or new planned fill. Quaternary Colluvium (Not Mapped) Quaternary colluvium was encountered at the surface in all the test pits and borings. As observed in the subsurface explorations, the colluvium typically consisted of dark grayish brown sandy silt, clayey sand , sandy clay, sand with trace silt, and silty sand with trace to locally abundant organics. Thecolluvium was generally dry to moist and loose to medium dense/stiff. The thickness of the colluvium was on the order of 1 foot to 2y2 feet. The colluvium is porous and considered potentially compressible in its existing state. As such, it should not be used for the support of settlement-sensitive improvements and/or new planned fill. Quaternary Paralic Deposits (Map Symbol - Qp) Quaternary paralic deposits were observed underlying the colluvium in all subsurface explorations. As observed, the upper approximately 1 foot to 4V2 feet of these deposits Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad ^ Marcti 13, 2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 4 were weathered and generally consisted of a porous strong brown, reddish yellow, reddish brown, and olive brown clayey sand; a brown, reddish yellow, olive brown, and reddish brown sandy clay; a brown and olive brown sandy silt; and a light reddish yellow, reddish yellow, and dark yellowish brown silty sand. The weathered paralic deposits were dry to moist and medium dense/very stiff to dense/hard. Unweathered paralic deposits were encountered at depths ranging from approximately 1 foot to 6V2 feet below the surface. Unweathered paralic deposits generally consisted of a strong brown, reddish brown, and reddish yellow clayey sand; a strong brown, reddish brown, reddish yellow, and olive brown sandy clay; and a reddish yellow silty sand. The unweathered paralic deposits were generally damp to moist and dense to very dense/hard. Trace to locally abundant iron- stone concretions and manganese oxide staining was observed in the finer grained weathered and unweathered paralic deposits, exposed in subsurface explorations performed in the lower elevations of the site (i.e., generally below an elevation of approximately 161 feet). Weathered paralic deposits are generally porous and considered potentially compressible in their existing state. Therefore, these surficial weathered sediments should not be used forthe support of settlement-sensitive improvements and/or planned fill. Unweathered paralic deposits are considered competent bearing materials. Structural Geology The paralic deposits exposed in the subsurface explorations were generally thickly bedded to massive with no discernable geologic structures. Regionally, paralic deposits are thickly bedded to massive with local subhorizontal bedding. No adverse geologic structures were observed on the site. GROUNDWATER GSI did not observe evidence of a regional groundwater table nor perched water within our subsurface explorations. Therefore, groundwater is not anticipated to significantly affect proposed site development, provided that the recommendations contained in this report are properly incorporated into final design and construction. These observations reflect site conditions at the time of 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. The regional groundwater table is likely coincident with MSL or approximately 156 feet below the lowest site elevation. Seeps, springs, or other indications of subsurface water were not noted on the subject property during the time of our field investigation, nor were such conditions observed in the adjoining streets to the northeast. However, perched water seepage may occur locally (as the result of heavy precipitation and/or irrigation, or damaged wet utilities) along zones of contrasting permeabilities/densities (fill/paralic deposit contacts, sandy/clayey fill lifts, etc.) or along geologic discontinuities. This potential should be anticipated and disclosed to all interested/affected parties. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad _ Marcti 13, 2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 5 Due to the potential for post-development perched water to manifest near the surface, owing to as-graded permeability/density contrasts, more onerous slab design is necessary for any new slab-on-grade floor (State of California, 2013). Recommendations for reducing the amount of water and/or water vapor through slab-on-grade floors are provided in the "Soil Moisture Considerations" sections of this report. ROCK HARDNESS/EXCAVATION DIFFICULTY During subsurface exploration, excavation with a mini-excavator below depths on the order of 4 to 5 feet below the existing grade in Test Pits TP-1 through TP-4 ranged from moderately to very difficult. Excavations ranged from easy to moderately difficult to the depths explored in the remaining subsurface explorations which were completed with a mini-excavator as well as hand equipment. To that end, it is our opinion that moderately to very difficult excavation, and possibly economic refusal, may be locally encountered below depths of approximately 4 to 5 feet below the existing grade, considering the use of light-weight excavation equipment (i.e., rubber-tire backhoe, mini-excavator, etc.). At this time, the need for rock buckets and rock-breaking equipment (i.e., hoe ram) cannot be entirely precluded for excavations completed into the paralic deposits. Excavation equipment should be appropriately suited for the required excavation task. Although not a geotechnical requirement, overexcavating underground utility corridors to at least 1 foot below the lowest underground utility invert during grading may be considered. This would allow for easier excavation during the construction of such improvements. GEOLOGIC HAZARDS EVALUATION 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. However, owing to their strength characteristics, the paralic deposits underlying the site have very low susceptibility to deep-seated landslides. In addition, geomorphic expressions indicative of mass wasting (i.e., scarps and hummocky terrain) were not observed during our field studies. Further, no adverse Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13, 2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 6 geologic structures were encountered during our subsurface exploration nor during our review of regional geologic maps. The onsite soils are, however, considered erosive. Therefore, slopes comprised of these materials may be subject to rilling, gullying, sloughing, and 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. FAULTING AND REGIONAL SEISMICITY Regional Faults Our review indicates that there are no known active faults crossing the project and the site is not within an Alquist-Priolo Earthquake Fault Zone (Bryant and Hart, 2007). However, the site is situated in a region subject to periodic earthquakes along active faults. The offshore segment of the Newport-lnglewood fault is the closest known active fault to the site (located at a distance of approximately 5.7 miles [9.2 kilometers]) and should have the greatest effect on the site in the form of strong ground shaking, should the design earthquake occur. The location of the Newport-lnglewood fault and other major faults relative to the site is shown on the "California Fault Map" in Appendix C. The possibility of ground acceleration, or shaking atthe site, maybe considered as approximately similar to the southern California region as a whole. Local Faulting Although active faults lie within a few miles of the site, no active faults were observed to specificallytransectthe site during the field investigation. Additionally, a review of available regional geologic maps does not indicate the presence of active faults crossing the specific project site. Based on our review of regional geologic maps, there are several short, discontinuous faults in the site vicinity. However, these faults are not designated by the State of California as active (i.e., lack Holocene movement). Surface Rupture Owing to the lack of known active or potentially active faults crossing the site, the potential for the proposed development to be adversely affected by surface rupture from fault movement is considered very low. Seismicity 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. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad GeoSoilS, InC. March 13, 2013 File:e:\wp12\6500\6524a.pge Page 7 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 EQFAULT. Based on the EQFAULT program, a peak horizontal ground acceleration from an upper bound event on the offshore segment of the Newport-lnglewood fault may be on the order of 0.57g. The computer printouts of pertinent portions ofthe EQFAULT program are included within Appendix C. Historical site seismicity was evaluated with the acceleration-attenuation relation of Bozorgnia, Campbell, and Niazi (1999), and the computer program EQSEARCH (Blake, 2000b, updated to December 2011). 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 December 2011. Based on the selected acceleration-attenuation relationship, a peak horizontal ground acceleration is estimated, which may have affected 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 through December 2011 was about 0.23 g. A historic earthquake epicenter map and a seismic recurrence curve are also estimated/generated from the historical data. Computer printouts ofthe EQSEARCH program are presented in Appendix C. A probabilistic seismic hazards analysis was performed using the 2008 Interactive Deaggregations (Beta [2012 update]) Seismic Hazard Analysis tool available atthe USGS website (https://geohazards.usgs.gov/deaggnit/2008/) which evaluates the site specific probabilities of exceedance for selected spectral periods. Based on a review of these data, and considering the relative seismic activity of the southern California region, a probabilistic horizontal ground acceleration (PHGA) of 0.49 g and 0.27 g were calculated. These values were chosen as they correspond to a 2 and 10 percent probability of exceedence in 50 years, respectively. The calculated values are within the range typical for the southern California region. Probabilistic vertical ground acceleration may be assumed as 50 percent of the PHGA. Printouts from this analysis are also included in Appendix C. Seismic Shaking Parameters Based on the site conditions, the following table summarizes the site-specific design criteria obtained from the 2010 CBC (CBSC, 2010), Chapter 16 Structural Design, Section 1613, Earthquake Loads. The computer program Seismic Hazard Curves and Uniform Hazard Response Spectra, provided by the United States Geologic Survey (U.S.G.S.) was utilized for seismic design values. The short spectral response utilizes a period of 0.2 seconds. This application also produces seismic hazard curves, and uniform hazard response spectra. Kraemer Land, Inc. ~ W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad ^ March 13,2013 File:6:\wp12\6500\6524a.pge GeoSollS, InC. Page 8 CBC SEISMIC DESIGN PARAMETERS PARAMETER VALUE 2010 CBC REFERENCE Site Class D Table 1613.5.2 Site Coefficient, F^, 1.0 Table 1613.5.3(1) Site Coefficient, F, 1.523 Table 1613.5.3(2) Maximum Considered Earthquake Spectral Response Acceleration (0.2 sec), S^g 1.265 Section 1613.5.3 (Eqn 16-36) Maximum Considered Earthquake Spectral Response Acceleration (1 sec), S,,,, 0.727 Section 1613.5.3 (Eqn 16-37) 5% Damped Design Spectral Response Acceleration (0.2 sec), S^s 0.843 Section 1613.5.4 (Eqn 16-38) 5% Damped Design Spectral Response Acceleration (1 sec), S^,, 0.485 Section 1613.5.4 (Eqn 16-39) GENERAL SEISMIC DESIGN PARAMETERS PARAMETER VALUE Distance to Seismic Source (Newport-lnglewood fault [offshore segment]) 5.7 mi (9.2 km)<'' Upper Bound Earthquake (Newport-lnglewood fault [offshore segment]) M„ 6.9<^'/M„ 7.1'^' Probabilistic Horizontal Ground Acceleration ([PHGA] 2%/10% probability of exceedance in 50 years, respectively).'"* 0.49g/0.27g - From Blake (2000a) - International Conference of Building Officials (ICBO, 1998) - Cao, et al., 2003 - Probabilistic Vertical Ground Acceleration may be assumed as about 50% of these values. 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 2010 CBC (CBSC, 2010) and regular maintenance and repair following locally significant seismic events (i.e., M„5.5) will likely be necessary, as is the case in all of southern California. Kraemer Land, Inc. APNs 156-200-01, -02, & -15, Carlsbad Flle;e:\wp12\6500\6524a.pge GeoSoils, Inc. W.o. 6524-A-SC March 13, 2013 Page 9 SECONDARY SEISMIC HAZARDS Liguefaction/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 ofthe 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, 2005]). 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. 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 two of these five necessary conditions have the potential to affect the site, concurrently. 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, 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 ofthe 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. Some densification ofthe 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 placed close to the Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 10 perimeter of the site. Our evaluation assumed that the current offsite conditions will not be significantly modified by future grading at the time ofthe 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 ofthe paralic deposits that underlie the site in the near-surface and the depth to the regional water table. In addition, the recommendations for remedial earthwork and foundations would further reduce any significant liquefaction/densification potential. Some seismic densification ofthe adjoining un-mitigated site(s) may adversely influence planned improvements at the perimeter ofthe site. However, given the remedial earthwork and foundation recommendations provided herein, the potential forthe planned building to be affected by significant seismic densification or liquefaction of offsite soils may be considered low. Other Geologic/Secondary Seismic Hazards The following list includes other geologic/seismic related hazards that have been considered during our evaluation ofthe 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 SLOPE STABILITY Assuming proper surface drainage, regular and periodic care and maintenance, and normal rainfall, permanent graded slopes, constructed from the onsite materials, are considered grossly and surficially stable. However, site earth materials are considered erosive. As such, positive surface drainage practices and vegetative covering should be maintained throughout the life of the project. Temporary slopes for construction are discussed in subsequent sections of our report. LABORATORY TESTING Laboratory tests were performed on representative samples of site earth materials collected during our subsurface exploration in order to evaluate their physical characteristics. Test procedures used and results obtained are presented below. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 11 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 Test Pit and Boring Logs in Appendix B. Moisture-Densitv Relations The field moisture contents and dry unit weights were determined for selected samples in the laboratory. Testing was performed in general accordance with ASTM D 2937 and ASTM D 2216. The dry unit weight was determined in pounds per cubic foot (pcf), and the field moisture content was determined as a percentage ofthe dry weight. The results of these tests are shown on the Test Pit and Boring Logs in Appendix B. Expansion Index Representative samples of near-surface site soils were evaluated for expansion potential. Expansion Index (E.I.) testing and expansion potential classification was performed in general accordance with ASTM Standard D 4829, The results ofthe expansion testing are presented in the following table. SAMPLE LOCATION AND DEPTH (FT) EXPANSION INDEX EXPANSION POTENTIAL TP-3 @ 4-5 23 Low HA-1 @ 3V2 - 4V2 <5 Very Low Atterberg Limits Tests were performed on a representative fine-grained soil sample to evaluate its liquid limit, plastic limit, and plasticity index (P.l.) in general accordance with ASTM D 4318-4318. The test results are presented below and Appendix D: SAMPLE LOCATION AND DEPTH (FT) PLASTIC LIMIT LIQUID LIMIT PLASTICITY INDEX TP-3 @ 4 -5 37 19 18 Kraemer Land, Inc. APNs 156-200-01, -02, & -15, Carlsbad File:e:\wp12\6500\6524a.pge GeoSoils, Inc. W.O. 6524-A-SC March 13, 2013 Page 12 Grain Size Distribution An evaluation was performed on a selected representative soil sample in general accordance with ASTM D 422. The grain-size distribution curve is presented in Appendix D. Direct Shear Shear testing was performed on a representative, relatively undisturbed sample 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 presented in the following table and in Appendix D: SAMPLE LOCATION AND DEPTH (FT) PRIMARY RESIDUAL SAMPLE LOCATION AND DEPTH (FT) COHESION (PSF) FRICTION ANGLE (DEGREES) COHESION (PSF) FRICTION ANGLE (DEGREES) TP-5 @ aV2 433 34 366 30 Saturated Resistivity, pH, and Soluble Sulfates, and Chlorides GSI conducted sampling of onsite earth materials for general soil corrosivity and soluble sulfates, and chlorides testing. The testing included evaluation of soil pH, soluble sulfates, chlorides, and saturated resistivity. Test results are presented in the following table: SAMPLE LOCATION AND DEPTH (FT) pH SATURATED RESISTIVITY (ohm-cm) SOLUBLE SULFATES (% by weight) SOLUBLE CHLORIDES (ppm) TP-1 @ 0-4 7.86 1,600 0.0650 95 Corrosion Summary Laboratory testing indicates that tested samples ofthe onsite soils are moderately alkaline with respect to soil acidity/alkalinity, are corrosive to exposed, buried metals when saturated, present negligible ("not applicable" per American Concrete Institute [ACI] 318-08) sulfate exposure to concrete, and are below action levels for chloride exposure (per State of California Department of Transportation, 2003). Reinforced concrete mix design for foundations, slab-on-grade floors, and pavements should minimally conform to "Exposure Class Cl" in Table 4.3.1 of ACI 318-08, as concrete would likely be exposed to moisture. It should be noted that GSI does not consult in the field of corrosion engineering. The client and project architect should agree on the level of corrosion Kraemer Land, Inc. APNs 156-200-01, -02, & -15, Carlsbad File:e:\wp12\6500\6524a.pge GeoSoils, Inc. w.o. 6524-A-SC March 13, 2013 Page 13 protection required for the project and seek consultation from a qualified corrosion consultant as warranted. PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS Based on our field exploration, laboratory testing, and geotechnical engineering analysis, it is our opinion that the subject site is suitable for the proposed residential 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 and improvements are: Earth materials characteristics and depth to competent bearing material. On-going expansion and corrosion potential of site soils. Erosiveness of site earth materials. Potential for perched water during and following site development. Perimeter conditions and planned improvements near the subdivision boundary. Temporary slope stability. Regional seismic activity. The recommendations presented herein considerthese as well as other aspects ofthe site. The engineering analyses performed concerning site preparation and the recommendations presented herein have been completed using the information provided and obtained during our 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 any grading and foundation construction to verify and/orfurther evaluate geologic conditions. Although unlikely, if adverse geologic structures are encountered, supplemental recommendations and earthwork may be warranted. 3. Undocumented fill, colluvium, and weathered paralic deposits are considered unsuitable for the support ofthe planned settlement-sensitive improvements (i.e., residential structures, walls, underground utilities, and pavements, etc.) and new Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad ^ March 13,2013 Flle:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 14 planned fills. Unsuitable soils within the influence of planned settlement-sensitive improvements and planned fill should be removed to expose unweathered paralic deposits and then be reused as properly engineered fill. Based on the available subsurface data, remedial grading excavations are anticipated to extend to depths of approximately 1 foot to 6V2 feet below the existing grade. However, locally deeper remedial grading excavations cannot be precluded and should be anticipated. 4. Expansion Index testing performed on a sample of the onsite soils indicates very low to low expansive soil conditions (Expansion Index [E.I.] = <5to23). Atterberg Limits testing on the finer grained soil sample indicates a plasticity index (P.l.) of 18. Thus, some ofthe onsite soils meet the criteria for detrimentally expansive soils as defined in Section 1803.5.2 ofthe 2010 CBC. On a preliminary basis, residential building foundations within the influence of expansive soils should be designed and constructed in accordance with Sections 1808.6.1 or 1808.6.2 of the 2010 CBC. Foundation systems used forthe mitigation of expansive soils typically incorporate the Post-tension Institute (PTI) and Wire Reinforcement Institute (WRI) methodologies. Preliminary recommendations for the design and construction of post-tension (PT) foundations are included herein. Final foundation design will be provided at the conclusion of grading, based on the E.I. and P.l. of soils exposed near pad grade. As an alternative to designing and constructing specialized foundation systems to reduce expansive soil effects, earthwork mitigation and/or selective grading may be performed to create a non-detrimentally expansive fill cap which may allow for a conventional foundation system. 5. Laboratory testing indicates that site soils are moderately alkaline with respect to soil acidity/alkalinity and are corrosive to exposed buried metals when saturated. Testing also indicates that site soils present negligible ("not applicable" per ACI 318-08) sulfate exposure to concrete and are below the action levels for chloride exposure. The client and project architect should agree on the level of corrosion protection required forthe project and seek consultation from a qualified corrosion consultant as warranted. 6. Site soils are considered erosive. Surface drainage should be designed to eliminate the potential for concentrated flows. Positive surface drainage away from foundations and tops of slopes is recommended. Temporary erosion control measures should be implemented until vegetative covering is well established. The homeowners and homeowner's association (if any) will need to maintain proper surface drainage over the life of the project. 7. No evidence of a high regional groundwater table nor perched water was observed during our subsurface exploration within the property. However, due to the nature of site earth materials, there is a potential for perched water to occur both during and following site development. This potential should be disclosed to all interested/affected parties. Should perched water conditions be encountered, this Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 15 office could provide recommendations for mitigation. Typical mitigation includes subdrainage system, cut-off barriers, etc. 8. The removal and recompaction of potentially compressible soils below a 1:1 (h:v) projection down from the bottom outside of planned settlement-sensitive improvements and fill along the perimeter ofthe site will be limited due to boundary restrictions. As such, any settlement-sensitive improvement located above a 1:1 (h:v) projection from the bottom outboard edge of the remedial grading excavation at the property line would require deepened foundations below this plane, additional reinforcement, or would retain some potential for distress and therefore, a reduced serviceable life. On a preliminary basis, any planned settlement-sensitive improvements located within approximately 1 foot and 6y2feet from the subdivision boundary would require deepened foundations or additional reinforcement by means of ground improvement or specific structural design. This should be disclosed to all interested/affected parties. The planned segmental retaining wall, south of Lots 6 and 11 will require a deepened foundation, owing to the inability to provide lateral support for the wall without offsite grading. 9. Ona preliminary basis, temporary slopes should be constructed in accordance with CAL-OSHA guidelines for Type "B" soils, provided water or seepage is not present. All temporary slopes should be evaluated by the geotechnical consultant, prior to worker entry. Should adverse conditions be identified, the slope may need to be laid back to a flatter gradient or require the use of shoring. 10. The seismicity-acceleration values provided herein should be considered during the design and construction of the proposed development. 11. General Earthwork and Grading Guidelines are provided atthe end of this report as Appendix E. Specific recommendations are provided below. EARTHWORK CONSTRUCTION RECOMMENDATIONS General All earthwork should conform to the guidelines presented in the 2010 CBC (CBSC, 2010), the requirements of the City of Carlsbad, and the General Earthwork and Grading Guidelines presented in Appendix E, 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 ofthe site, or backfilling underground utility trenches and retaining walls after rough earthwork has been completed. This includes grading for driveway approaches, driveways, and exterior hardscape. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad GeoSoilS, InC. March 13, 2013 File:e:\wp12\6500\6524a.pge Page 16 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 improvements, 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. Mitigation of cavities would likely include removing any potentially compressible soils to expose unweathered paralic deposits and then backfilling the excavation with a controlled engineered fill or soils that have been moisture conditioned to optimum moisture content and compacted to at least 90 percent ofthe laboratory standard (ASTM D 1557). Removal and Recompaction of Potentially Compressible Earth Materials Potentially compressible undocumented fill, colluvium, and weathered paralic deposits should be removed to expose unweathered paralic deposits. Following removal, these soils should be cleaned of any vegetation and deleterious debris, moisture conditioned to at least the soil's optimum moisture content, and then be recompacted to at least 90 percent of the laboratory standard (ASTM D 1557). Based on the available data, excavations necessary to remove unsuitable soils are anticipated to range between approximately 1 foot and 6V2 feet below the existing grade. The potential to encounter thicker sections of unsuitable soils that require deeper remedial grading excavations than stated above cannot be precluded and should be anticipated. Potentially compressible soils should be removed below a 1:1 (h:v) projection down from the bottom, outboard edge of any settlement-sensitive improvement or limits of planned fill. Remedial grading excavations should be observed by the geotechnical consultant prior to scarification and fill placement. Once observed and approved, the bottom of the remedial grading 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 ofthe laboratory standard (ASTM D 1557). Owing to the age of the existing development at the site, it is possible that underground structures (i.e., cisterns, seepage pits, etc.) may be encountered during remedial grading. This office should be informed if any underground structures are encountered during remedial earthwork. Based on exposed conditions, this office would provide recommendations for mitigation. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad ^ March 13,2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 17 Perimeter Conditions It should be noted that the 2010 CBC (CBSC, 2010) indicates that removals of unsuitable soils be performed across all areas to be graded, under the purview ofthe grading permit, not just within the influence of the 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 ofthe remedial grading excavation at the subdivision boundary would be affected by perimeter conditions. On a preliminary basis, any planned settlement-sensitive improvements located within approximately 1 foot and 6V2 feet from the subdivision boundary would require deepened foundations or additional reinforcement by means of ground improvement or specific structural design, for perimeter conditions discussed above. Otherwise these improvements may be subject to distress and a reduced serviceable lifespan. 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 Following scarification ofthe bottom ofthe remedial grading excavation, the 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 the soil's optimum moisture content, and compacted to achieve a minimum relative compaction of 90 percent of the laboratory standard (ASTM D 1557). Overexcavation In order to provide uniform foundation and slab-on-grade floor support, it is recommended that unweathered paralic deposits located within 36 inches of pad grade or 24 inches below the lowest bottom of residential footing elevation (whichever is greater), following the removal of potentially compressible soil, be overexcavated to at least 36 inches below pad grade or24 inches belowthe lowest bottom-of-footing-elevation (whichever is greater), and be replaced with engineered fill prepared and placed in accordance with the previous recommendations. Overexcavation should be completed across the entire building pad in case the location of the building footprint requires modification after grading. The bottom of the overexcavation should be graded such that it slopes away from the residential structure, preferably toward a street. The maximum:minimum fill thickness across a lot should not exceed 3:1 (maximum:minimum). Prior to fill placement, the bottom of the overexcavation 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 ofthe laboratory standard (ASTM D 1557). If dense homogenous paralic deposits are exposed at pad grade, overexcavation is still recommended to reduce the potential for perched water manifestation. Overexcavation for engineered fill/paralic deposit transitions in the planned cul-de-sac street is not necessary. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad ^ March 13,2013 File:e:\wp12\6500\6524a.pge GCOSoilS, InC. Page 18 As previously indicated, excavations for underground utility trenches that extend into paralic deposits below depths on the order of 4 to 5 feet from the existing grade could range from moderately to very difficult, especially if lightweight excavation equipment is used. Therefore, the Client may consider overexcavating utility corridors to at least 1 foot belowthe lowest utility invert during grading and replacing these materials with engineered fill, placed in accordance with the recommendations described above, to help facilitate trenching for underground utilities. Overexcavation for underground utilities is not a geotechnical requirement, however. Expansive Soil Mitigation/Selective Grading As an alternative to designing and constructing specialized foundation and slab-on-grade floor systems to resist expansive soil effects, selective grading techniques may be undertaken to potentially create a non-detrimentally expansive soil cap. Selective grading techniques may include the removal and replacement of expansive soils within the upper 7 feet of finish grade and 7 feet outside the building footprint with very low expansive and very low plastic (E.I. = 0 to 20 and P.l. less than 15) native and/or import soils. Alternatively, very low expansive and very low plastic native and/or import soils may be blended with the onsite expansive soils. If the latter is selected, GSI recommends a blend ratio (by volume) of at least 3 :1 (very low expansive and very low plastic native and/or import soils to onsite expansive soils) on a preliminary basis. This should be re-evaluated during grading based on selective sampling and testing. Import Soils If import fill is necessary, a sample ofthe 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 three 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 should be non-detrimentally expansive (i.e., E.I. less than 21 and plasticity index P.l. less than 15). The use of subdrains at the bottom ofthe fill cap may be necessary, and may be subsequently recommended based on compatibility with onsite soils. Graded Slope Construction Graded fill slopes should be constructed at gradients no steeper than 2:1 (h:v) to the heights shown on LE&S (2013) without further analysis. Fill slopes should be properly keyed and benched is constructed along surfaces steeper than 5:1 (h:v). All fill slopes should be compacted to at least 90 percent of the laboratory standard (ASTM D 1557) throughout, including the slope face. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13, 2013 File;e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 19 Graded cut slopes should be constructed at gradients no steeper than 2:1 (h:v) to the heights shown on LE&S (2013) without further analysis. All cut slopes should be mapped by a geologist during construction. Although not anticipated at this time, should bedding planes of weak earth materials, cohesionless sands, or intersecting planes of joints/fractures daylight the cut slope face, or should undocumented fill, colluvium, or highly weathered paralic deposits be exposed in cut slopes, remedial grading including stabilization fills or inclining the cut slope to a gradient flatter than the adverse structure may be necessary. The type of remedial grading would be based on the conditions exposed during cut slope construction. 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 is 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 temporary slopes conflict with property boundaries, 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. Excavation Observation and Monitoring (All Excavations) When excavations are made adjacent to an existing improvement (i.e., utility, road or building) 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 y2-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. Monitoring should include the measurement of any horizontal and vertical movements of the existing structures/improvements. Locations and type ofthe monitoring devices should be selected priorto 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, priorto excavation. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13,2013 File;e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 20 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 ofthe 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 ofthe existing structures both before and after construction. The inspection should be directed toward detecting any signs of damage, particularly those caused by settlement. Notes should be made and pictures 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) 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 Artificial Fill 5% to 10% shrinkage Colluvium 3% to 8% shrinkage Weathered Paralic Deposits 2% to 3% shrinkage or bulk Terrace Deposits 2% to 3% shrinkage or bulk It should be noted that the above factors are estimates only, based on preliminary data. Existing fill and colluvium may achieve higher shrinkage if organics or clay content is higher than anticipated, or if compaction averages more than 92 percent ofthe laboratory standard (ASTM D 1557). Final earthwork balance factors could vary. In this regard, it is recommended that balance areas be reserved where grades could be adjusted up or Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad ^ March 13, 2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 21 down near the completion of grading in order to accommodate any yardage imbalance for the project. 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 planned site development, site observations, subsurface exploration, laboratory testing, and engineering analyses. 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 ofthe 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 related to foundation design. In the following sections, GSI provides preliminary design and construction recommendations for foundations underlain by both non-detrimentally and detrimentally expansive soil conditions. Foundations systems constructed within the influence of detrimentally expansive soils (i.e., E.I. > 20 and PI >^ 15) will require specific design to resist expansive soil effects per Sections 1808.6.1 or 1808.6.2 ofthe 2010 CBC. Preliminary Foundation Design 1. The foundation systems should be designed and constructed in accordance with guidelines presented in the 2010 CBC. 2. An allowable bearing value of 1,500 pounds per square foot (psf) may be used for the design of footings that maintain a minimum width of 12 inches and a minimum depth of 12 inches (below the lowest adjacent grade), and are founded entirely into approved engineered fill. This value may be increased by 20 percent for each additional 12 inches in footing depth to a maximum value of 2,500 psf for footings founded into approved engineered fill. This value may be increased by one-third when considering short duration seismic or wind loads. Isolated pad footings should have a minimum dimension of at least 24 inches square and a minimum embedment of 24 inches below the lowest adjacent grade into approved Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13, 2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 22 engineered fill. Foundation embedment depth excludes concrete slabs-on-grade, and/or slab underlayment. 3. For foundations deriving passive resistance from approved engineered fill, a 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. 4. The upper 6 inches of passive pressure should be neglected if not confined by slabs or pavement. 5. 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. 6. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. 7. All footing setbacks from slopes should comply with Figure 1808.7.1 of the 2010 CBC. GSI recommends a minimum horizontal setback distance of 7 feet as measured from the bottom, outboard edge ofthe footing to the slope face. 8. Footings for structures adjacent to retaining walls should be deepened so as to extend below a 1:1 projection up from the heel of the wall or geogrid-reinforced zone (whichever is greater). PRELIMINARY FOUNDATION CONSTRUCTION RECOMMENDATIONS Conventional Foundation and Slab-On-Grade Floor Systems The following recommendations are intended to support foundations and slab-on-grade floor systems underlain by at least 7 feet of non-detrimentally expansive soils (i.e., E.l.<21 and P.l. <15). 1. Exterior and interior footings should be founded into approved engineered fill at a minimum depth of 12 or 18 inches below the lowest adjacent grade for one- or two-story floor loads, respectively. For one- and two-story floor loads, footing widths should be 12 and 15 inches, respectively. Isolated, exterior column and panel pads, or wall footings, should be at least 24 inches square, and founded at a minimum depth of 24 inches into approved engineered fill. All footings should be minimally reinforced with four No. 4 reinforcing bars, two placed near the top and two placed near the bottom of the footing. 2. All interior and exterior column footings, and perimeter wall footings, should be tied together via grade beams in at least one direction. The grade beam should be at least 12 inches square in cross section, and should be provided with a minimum of Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad _ March 13, 2013 File:e:\wp12\6500\6524a.pge GeoSollS, InC. Page 23 one No.4 reinforcing bar at the top, and one No.4 reinforcing bar at the bottom of the grade beam. The base of the reinforced grade beam should be at the same elevation as the adjoining footings. 3. A grade beam, reinforced as previously recommended and at least 12 inches square, should be provided across large (garage) entrances. The base of the reinforced grade beam should be at the same elevation as the adjoining footings. 4. A minimum concrete slab-on-grade thickness of 5 inches is recommended. 5. Concrete slabs should be reinforced with a minimum of No. 3 reinforcement bars placed at 18-inches on center, in two horizontally perpendicular directions (i.e., long axis and short axis). 6. All slab reinforcement should be supported to ensure proper mid-slab height positioning during placement ofthe concrete. "Hooking" of reinforcement is not an acceptable method of positioning. 7. Slab subgrade pre-soaking is not required for non-detrimentally expansive soil conditions. However, the client should consider pre-wetting the slab subgrade materials to at least the soil's optimum moisture content to a minimum depth of 12 inches, priorto the placement ofthe underlayment sand and vapor retarder. 8. Soils generated from footing excavations to be used onsite should be compacted to a minimum relative compaction of 90 percent of the laboratory standard (ASTM D 1557), whether the soils are to be placed inside the foundation perimeter or in the yard/right-of-way areas. This material must not alter positive drainage patterns that direct drainage away from the structural areas and toward the street. 9. Reinforced concrete mix design should conform to "Exposure Class Cl" in Table 4.3.1 of ACI-318-08 since concrete would likely be exposed to moisture. Post-Tensioned Foundations Post-tension (PT) foundations should be used to mitigate the damaging effects of expansive soils on the planned residential foundations and slab-on-grade floors if expansive soil conditions are encountered within 7 feet of finish grade. They may also be used for increased performance of foundations constructed on non-detrimentally expansive soils. Current laboratory testing indicates that some of the onsite soils below an approximate elevation of 161 feet have an E.I. of 23 and a P.l. of 18. These soils meet the criteria of detrimentally expansive soils as defined in Section 1803.5.2 ofthe 2010 CBC. Thus, GSI is providing geotechnical parameters for the design of PT foundations within the influence of such soil conditions. In addition, GSI is also providing geotechnical design Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad ^ March 13, 2013 File:e:\wpl2\6500\6524a.pge GeoSoilS, InC. Page 24 recommendations for PT foundations within the influence of medium expansive soils (E.I. = 51 to 90) in the unlikely event that these soil conditions are encountered. The PT foundation designer may elect to exceed these minimal recommendations to increase slab stiffness performance. 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 (i.e., that method typically uses a single perimeter grade beam and possible "shovel" footings), but has a thicker slab than the ribbed-type. 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. PT foundations should be designed using sound engineering practice and be in accordance with local and 2010 CBC requirements. Upon request, GSI can provide additional data/consultation regarding soil parameters as related to post- tensioned 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" ofthe 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 ofthe 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 expand and cause 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 transfer regime is reversed and the soils underneath the slab edges lose their moisture and shrink. This process leads to dropping ofthe slab atthe edges, which leads to what is commonly referred to as the center lift condition. A well-designed, PT 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 priorto the PT 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 ofthe concrete slab that impedes both outward and inward soil moisture migration. Soil Moisture Specific pre-moistening and moisture testing of the slab subgrade is recommended for expansive soil conditions (i.e., E.I. > 20 and P.l. >^ 15). The moisture content of the Kraemer Land, Inc. ~ W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13, 2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 25 subgrade soils should be 1.1 to 1.2 times greater than soil's optimum moisture to a depth equivalent to the exterior footing depth in the slab areas (typically 12 or 18 inches for low [E.I. = 21 to 50] or medium [E.I. = 51 to 90] expansive soils, respectively). Pre-moistening and/or pre-soaking should be evaluated by the soils engineer 72 hours prior to vapor retarder placement. For very low expansive soil conditions (E.I. < 21 and P.l. <15) slab subgrade pre-wetting to at least optimum moisture conditions for a depth of 12 inches should be considered. However, this is not a geotechnical requirement. Perimeter Cut-Off Walls Perimeter cut-off walls should be 12 or 18 inches deep for very low to low, or medium 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. The bottom ofthe perimeter cut-off wall should be designed to resist tension, using cable or reinforcement per the structural engineer. Post-Tensioned 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 Institute's (PTI's) publication titled "Design of Post-Tensioned Slabs on Ground, Third Edition" (PTI, 2004), together with it's subsequent addendums (PTI, 2008). 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 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. 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 Constant soil Suction (pf) 3.6 Moisture Velocity 0.7 inches/month Plasticity Index (P.l.) < 15-50 Based on the above, the recommended soil support parameters are tabulated below: Kraemer Land, Inc. APNs 156-200-01, -02, & -15, Carlsbad File:e:\wp12\6500\6524a.pge GeoSoils, Inc. w.o. 6524-A-SC March 13, 2013 Page 26 DESIGN PARAMETERS VERY LOW TO LOW EXPANSION (E.I. = 0-50) MEDIUM EXPANSION (E.I. = 51-90) e^ center lift 9.0 feet 8.7 feet e„ edge lift 4.75 feet 4.5 feet y„ center lift 0.5 inches 0.8 inches edge lift 0.7 inch 1.3 Inch Bearing Value 1,500 psf 1,000 psf Lateral Pressure 250 psf 175 psf Subgrade Modulus (k) 100 pci/inch 70 pci/inch Minimum Perimeter Footing Embedment 12 inches 18 inches Internal bearing values within the perimeter ofthe post-tension slab may be increased to 1,500 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. '^'AS measured below the lowest adjacent compacted subgrade surface without landscape layer or sand underlayment. Note: The use of open bottomed raised planters adjacent to foundations will require more onerous design parameters. The parameters are considered minimums and may not be adequate to represent all expansive soils/drainage 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. Foundation Settlement Provided that the earthwork and foundation recommendations in this report are adhered, foundations bearing on approved engineered fill should be minimally designed to accommodate a total settlement of 1 y2 inches and a differential settlement of %-inch over a 40-foot horizontal span (angular distortion = 1/640). Kraemer Land, Inc. APNs 156-200-01, -02, & -15, Carlsbad File:e:\wp12\6500\6524a.pge GeoSoils, Inc. w.o. 6524-A-SC March 13, 2013 Page 27 SOIL MOISTURE TRANSMISSION CONSIDERATIONS GSI has evaluated the potential for vapor or water transmission through the concrete floor slab, 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 (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, 2013). 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 oftime 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 slabs including garages should be a minimum of 5 inches thick. Concrete slab underlayment should consist of a 15-mil vapor retarder, or equivalent, with all laps sealed per the 2010 CBC and the manufacturer's recommendation. The vapor retarder should comply with the ASTM E 1745 - Class A criteria, 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 areas, shall be underlain by 2 inches of clean, washed sand (SE >^ 30) above a 15-mil vapor retarder (ASTM E-1745 - Class A, per Engineering Bulletin 119 [Kanare, 2005]) installed per the recommendations ofthe manufacturer, including all penetrations (i.e., pipe, ducting, rebar, etc.). The manufacturer shall provide instructions for lap sealing, including minimum width of Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 28 lap, method of sealing, and either supply or specify suitable products for lap sealing (ASTM E 1745), and per code. 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 lots with very low to low expansive soil conditions, the vapor retarder shall be underlain by 2 inches of sand (SE 30) placed directly on the prepared, moisture conditioned, subgrade and should be sealed to provide a continuous retarder under the entire slab, as discussed above. As discussed previously, GSI indicated this layer of import sand may be eliminated below the vapor retarder, if laboratory testing indicates that the slab subgrade soil have a sand equivalent (SE) of 30 or greater. For lots with medium expansive soil condition, the vapor retarder should be underlain by at least 4 inches of clean crushed gravel with a maximum dimension of y4-inch (less than 5 percent passing the No. 200 sieve). The gravel should be placed on the prepared subgrade described above. Concrete should have a maximum water/cement ratio of 0.50. This does not supercede Table 4.3.1 of Chapter 4 of the ACI (2008) for corrosion or other corrosive requirements. 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 homeowners should be specifically advised which areas are suitable for tile flooring, vinyl flooring, or othertypesofwater/vapor-sensitive flooring and which are not suitable. 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. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13, 2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 29 Regardless ofthe mitigation, some limited moisture/moisture vapor transmission through the slab 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. Atechnical representative ofthe flooring contractor should reviewthe slab and moisture retarder plans and provide comment priorto the construction ofthe foundations or improvements. The vapor retarder contractor should have representatives onsite during the initial installation. WALL DESIGN PARAMETERS CONSIDERING EXPANSIVE SOILS 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 up to 20 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 plans. Building walls, below grade, should be water-proofed. The foundation system forthe proposed retaining walls should be designed in accordance with the recommendations presented in this and preceding sections of this report, as appropriate. Retaining wall footings should be embedded a minimum of 18 inches below the lowest adjacent grade (excluding landscape layer, 6 inches) and should be at least 24 inches in width. There should be no increase in bearing for footing width. As indicated previously, planned retaining wall footings near the perimeter ofthe site will likely need to be deepened into unweathered paralic deposits for adequate vertical and lateral bearing support. Preliminary recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) have also been included in this report. Restrained Walls Any retaining walls that will be restrained priorto 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 and very low to low expansive native backfill, 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 10 feet high. Design parameters for walls less than 3 feet in height may be superceded by San Diego regional standard design. Active earth pressure may be used for retaining wall design, provided the top ofthe wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad ^ March 13,2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 30 Appropriate fluid unit weights are given below for specific slope gradients ofthe 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 should incorporate the surcharge of traffic on the back of retaining walls. The traffic surcharge may be taken as 100 psf/ft in the upper 5 feet of backfill for light truck and car traffic within "H" feet from the back of the wall, where "H" equals the wall height. 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. SURFACE SLOPE OF RETAINED MATERIAL (HORIZONTAL:VERTICAL) EQUIVALENT FLUID WEIGHT P.C.F. (SELECT BACKFILL)"^* EQUIVALENT FLUID WEIGHT P.C.F. (NATIVE BACKFILL)'*' Level'^' 2 to 1 45 65 55 70 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. SE > 30, P.l. < 15, E.I. < 21, and <^ 10% passing No. 200 sieve. E.I. = 0 to 20, SE > 25, P.l. < 15, and < 15% passing No. 200 sieve. Seismic Surcharge For engineered retaining walls that may pose ingress or egress constraints to structures, GSI recommends that such walls be evaluated for a seismic surcharge (in general accordance with 2010 CBC requirements). The site 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 ofthe 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 "H" for retained walls is the dimension previously noted as the height of the backfill to the bottom of the footing. The resultant force should be applied at a distance 0.6 H up from the bottom ofthe footing. Forthe evaluation ofthe seismic surcharge, the bearing pressure may exceed the static value by one-third, considering the transient nature of this surcharge. For cantilevered walls the pressure should be an inverted triangular distribution using 15H. Reference for the seismic surcharge is Section 1802.2 of the 2010 CBC. Please note this is for local wall stability only. Kraemer Land, Inc. APNs 156-200-01, -02, & -15, Carlsbad File:e:\wp12\6500\6524a.pge GeoSoils, Inc. w.o. 6524-A-SC March 13, 2013 Page 31 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 ofthe sand fill soil in the zone of influence from the wall or roughly a 45° - (t)/2 plane away from the back ofthe wall. The 15H seismic surcharge is derived from the formula: Ph = % • \ • YtH Where: = Seismic increment aj, ^ Probabilistic horizontal site acceleration with a percentage of "g" = total unit weight (115 to 125 pcf for site soils @ 90% relative compaction). H = 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. 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 y4-inch to iy2-inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent). For select backfill, the filter material should extend a minimum of 1 horizontal foot behind the base ofthe 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 greaterthan 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 ofthe laboratory standard (ASTM D 1557). 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 ofthe 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. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad _ March 13, 2013 File:e:\wp12\6500\6524a.pge GcoSoilS, InC. Page 32 Structural footing or settlement-sensitive improvement (1) Waterproofing membrane CMU or reinforced-concrete wall Proposed grade sloped to drain per precise civil drawings (5) Weep hole Footing and wall design by oihers—^^:^ Native backfill 11 (h:v) or flatter backcut to be properly benched (6) Footing (1) Waterproofing membrane. (2) Graveh Clean, crushed, % to 1)2 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: |f 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. Geijff'iiiii^ iJfinc. RETAINING WALL DETAIL - ALTERNATIVE A Detail 1 (1) Waterproofing membrane (optional) CMU or reinforced-concrete wall Structural footing or settlement-sensitive improvement Provide surface drainage via engineered (see civil plan details) (5) Weep hole Proposed grade sloped to drain per precise civil drawings Footing and wall design by others Native backfill 1:1 (h:v) or flatter backcut to be properly benched (6) 1 cubic foot of ^<4"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, % to % 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 wili likely be required by geotechnical consultant. Ge&!S0U$i inc. RETAINING WALL DETAIL - ALTERNATIVE B Detail 2 (1) Waterproofing membrane CMU or reinforced-concrete wall Structural footing or settlement-sensitive improvement Provide surface drainage slope Footing and wall design by others (5) Weep hole Proposed grade sloped to drain per precise civil drawings ^^i^. (3) Filter fabric (2) Gravel (4) Pipe (7) Footing (8) Native backfill (6) Clean sand backfill 1:1 (h:v) or flatter backcut to be properly benched (1) Waterproofing membrane: Liquid boot or approved masticequivalent. (2) Gravel: Clean, crushed, % to 1)^ inch. (3) Filter fabric: Mirafi MON 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 backfilh Must have sand equivalent value (S.E.) of 35 or greater; can be densified by water jetting upon approval by geotechnical engineer. (7) Footing: |f 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 backfilh If E.I. <21 and S.E. >35 then all sand requirements also may not be required and will be reviewed by the geotechnical consultant. RETAINING WALL DETAIL - ALTERNATIVE C Detail 3 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 ofthe 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 ofwhether 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. PRELIMINARY SEGMENTAL RETAINING WALL PARAMETERS It is our understanding that proposed development includes the construction of two segmental geogrid-reinforced retaining walls with a maximum retained height on the order of 5 feet (plus wall embedment in accordance with NCMA [National Concrete Masonry Association] guidelines and the recommendations included herein. Given that the segmental retaining wall planned at the south sides of Lots 6 and 11 will be constructed at the property line, wall embedment for lateral support may be up to 6y2 feet below the existing grade. Thus, given this wall's 4-foot planned maximum height, the geotechnical design parameters, provided below, are for segmental retaining walls up to 10y2 feet in overall height. The segmental retaining wall design parameters, provided herein, assume that either non- expansive soils (typically Class 2 permeable filter material or Class 3 aggregate base) or select soil import materials (up to and including an E.I. of 20, a P.l. <.5, and <^ 10 percent passing the No. 200 sieve) are used to backfill any segmental retaining walls. Based on the available data, some of the onsite soils are considered expansive and should not be used in segmental retaining wall construction. There is potential thatthe non-detrimentally expansive, granular soils located above an approximate elevation of 161 may be used as segmental retaining wall backfill, provided laboratory testing indicates acceptable expansion and plasticity indices, grain size, and strength characteristics (as evaluated by Kraemer Land, Inc. ~ W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GcoSoilS, InC. Page 36 the geotechnical engineer and wall designer). The type of backfill, should be specified by the wall designer, and clearly shown on the plans. Onsite earth materials primarily consist of localized undocumented fill, colluvium, and paralic deposits. These materials appear to predominantly range from clayey sand, silty sand, sandy silt, sandy clay, and poorly graded sand. Due to the variability of earth materials throughout the site, the related soil parameters should be anticipated as non-uniform. Granular fill soils generated from planned excavations into the paralic deposits excavations, near the westerly margin of the site, appear to be of better quality with regard to overall strength and could potentially be used in segmental retaining wall construction, if supported by laboratory testing. Fill materials derived from undocumented fill, colluvium, weathered paralic deposits, and paralic deposits below an approximate elevation of 161 feet will generally have lower strength and/or higher expansion and plasticity indices, and should not be used in wall design as fill or backfill. GSI does not recommend the use of the onsite soils in the segmental retaining wall construction until testing is performed and the materials are approved in writing by the geotechnical consultant as well as the segmental retaining wall designer, prior to construction and/or use. This will need to be considered during project planning, design, and construction. If not considered as described above, it may result in wall re-design during or after site grading. Guidelines for Segmental Retaining Wall Construction Segmental retaining walls are, by nature, a flexible system and, as such, not suited for every slope support condition. This will need to be considered and ultimately determined by the project design civil engineer and client. Slope and structural setbacks from the heel of walls and/or geogrid will be necessary, owing to potential deflection/movement. The necessary setbacks should be defined by the various project consultants and approved by the governing agencies priorto final design. At a minimum, the building setback should be up at a 1:1 (h:v) projection from the heel of the segmental wall foundation or the geogrid (whichever is more), and should be shown on the precise grading plans by the design civil engineer. Building setback mitigation may be accomplished by deepening any adjoining foundations through this zone of 1:1 projection, provided this does not disturb any geogrid. Generally, GSI does not recommend placing grid (walls) beneath foundations. In addition, building surcharge within the zone of influence for the geogrid should be included in wall evaluations. In addition to the previous recommendations, the following are specific recommendations for segmental retaining wall design and construction. These recommendations have been provided in an effort to achieve the most desirable and efficient means of construction. Some of these do not deal specifically with geotechnical aspects, but do have significant effects on the guality ofthe end product. As project geotechnical consultants, we feel that strong consideration should be given to these recommendations. If more onerous project specifications are required by the manufacturer or governing agency, then those guidelines should be followed. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13,2013 Flle:e:\wp12\6500\6524a.pge GeoSollS, InC. Page 37 Compared to conventional retaining walls, segmental retaining walls require significantly more geotechnical observation and testing. The costs for these services depend on wall size, conscientiousness ofthe contractor, the numberof backfill sources, and other factors. GSI should evaluate the geotechnical aspects of the wall layouts (offsets, cross-section, alignments) priorto construction. This approval by the geotechnical consultant should be sought (in writing) priorto 100 percent submittal by the wall designer. Foundation 1. Prior to excavation for the wall base, the alignment and grade for the wall should be established in the field by the project civil engineer or project surveyor. 2. The contractor should have a qualified grade checker onsite to continually verify the gradient (or batter) and alignment of the base excavation and wall during construction. 3. Defective segments or wall units should not be utilized. 4. The project surveyor should spot-check wall gradient (face-of-wall slope) and alignment and using this data, the civil design/wall designer should evaluate if the wall installation is per plan. 5. When locating the base ofthe wall, structural setbacks established by the governing agency, and/or geotechnical engineer should be followed. 6. Walls should be founded on engineered fill approved by this office, or dense, unweathered paralic deposits. GSI recommends that the segmental wall footing for the planned wall south of Lots 6 and 11 be deepened at least 1 foot into unweathered paralic deposits for adequate lateral support. 7. The recommended equivalent fluid pressure for design of the segmental retaining walls should be 45 pcf for level backfill and 65 pcf for 2:1 backfill, assuming the use of granular backfill material (E.I. ^20, P.l. ^6, (J) ^29 degrees, c = 0 psf, and <^10 percent passing the No. 200 sieve). These equivalent fluid pressures are based solely on static soil conditions and do not include seismic loading, expansive soil pressures, earthwork surcharge, or traffic loading which will need to be included, as necessary. 8. Utilize a seismic increment of 15H when evaluating internal stability of segmental retaining walls. The load should be applied as an inverted triangular distribution. For global stability of segmental retaining walls, a seismic factor (pseudo-static) of 0.15 /, should be used. 9. A bearing value 1,500 psf for a 1 foot deep footing into approved engineered fill or unweathered paralic deposits. For foundations deriving passive resistance from Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GcoSollS, InC. Page 38 approved engineered fill or unweathered paralic deposits, a 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. A friction coefficient of 0.30 may be used for a concrete to soil contact. A minimum friction angle of 29 degrees and a soil unit weight of 125 to 128 pcf may be utilized for the compacted fill, as evaluated by observation and/or testing. In addition, a cohesion value of 0 psf, for reinforced fill, 100 psf for retained fill, and 100 psf for foundation fill may be utilized. 10. Prior to placement of the segmental wall units, the excavation for the wall base should be observed by representatives of this firm, and should be a minimum of 12 inches into approved engineered fill or sediments. However, if medium expansive materials are exposed atthe foundation elevation, the minimum required depth should be 18 inches below the lowest adjacent grade. This is considered likely for the segmental retaining wall south of Lots 6 and 11. 11. A crushed stone leveling pad may be used to provide a uniform surface forthe wall base. 12. If it is necessary to locally deepen the wall base to obtain suitable bearing materials, the contractor should consult the project design engineer to determine if the wall location or design ofthe wall is affected. 13. Segmental retaining wall height at the terminal ends of the wall should not exceed 4 feet, unless lateral support is provided. Backfill 1. Fill placed within the geotextile reinforcement zone, and in front of the segmental retaining walls, should be compacted to a minimum of 90 percent relative compaction unless othenwise specified by the manufacturer. Any backfill other than the "unit core fill (% inch crushed rock or stone)" should be placed in controlled lifts not to exceed 6 inches in thickness, and moisture-conditioned as necessary to achieve at least optimum moisture content. Backfill within and immediately behind the walls should also be as indicated on the (precise and rough) grading plans. 2. Backfill materials should be free draining, and free from organic materials, with an E.I. less than 20, a Plasticity Index less than 6, and a maximum of 10 percent fines passing the No. 200 sieve. Lifts should be placed horizontally and compaction equipment should not be allowed to damage the geotextile reinforcement, where utilized. 3. If gravel or other select granular material is used as backfill within or behind the segmental retaining wall, it should be capped with a minimum 18 inches compacted fill composed of relatively impervious material. A layer of filter fabric (Mirafi MON or approved equivalent) should separate the gravel from the soil cap. Kraemer Land, Inc. ~ W.0.6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GCOSollS, InC. Page 39 4. During construction, the unfilled section of wall should not be stacked more than 2 feet above the fill behind the wall. If gravel is used to fill the wall, the wall may be stacked 3 feet above adjacent grades. The maximum gravel size should be less than % inch. If this option is selected, additional review with respect to drainage and potential for backfill scouring and/or piping at the face of the wall should be performed. Gravel (if used) should be separated from any adjacent soil with filter fabric (Mirafi MON or approved equivalent). 5. Adequate space should be provided both behind and in front of the wall so that sufficient compaction can be obtained for all backfill. The slope ofthe segmental retaining walls and benching (in cross-section and alignment) should be in accordance with the manufacturer's recommendations and as approved by the geotechnical consultant. Wall Back Drains A drainage system should be installed for all segmental retaining walls in excess of 3 feet in overall height. The design of the system will depend on specific conditions. For most cases, a Schedule 40 perforated drain pipe (Schedule 40 or approved equivalent), encased in clean crushed y2- to y4-inch gravel, and wrapped in Mirafi MON filter fabric (or approved equivalent). The drain should be placed atthe heel of the wall with a full height gravel drain, separated from the native backfill materials by Mirafi 140, or equivalent. In areas where paralic deposits and/or perched water are exposed in the backcut of the geotextile reinforced zone, a secondary backdrain system, of similar construction, should be placed at the toe of the backcut and along zones of perched water seepage. If necessary, outlets may pass below the base ofthe wall at a minimum 2 percent gradient. Outlets should be tight-lined via a solid drain pipe (Schedule 40 or approved equivalent) that drain toward an approved outlet area in accordance with the design civil engineer's recommendations. A concrete cut-off wall should be constructed at the connection between solid and perforated drain pipes to force seepage water into the solid pipe. The cut-off wall should surround the pipe connection and extend at least 12 inches beyond the outer edge of the pipe (in all directions [360 degrees]). The trenches for the solid drain pipe should be backfilled with either compacted fill material or gravel. If gravel is used, it should be separated from the surrounding soils with Mirafi MON filter fabric and should be capped with at least 12 inches of compacted fill material. Seepage should be anticipated below all segmental retaining walls, and this should be disclosed to all interested/affected parties. Materials and Wall Construction Only sound segmental retaining wall units/members and components that meet all required specifications should be used for construction ofthe walls. Wall units/members should be free of honeycombing, cracks, broken lugs, or slumped bearing surfaces. All geotextile reinforcement should comply with the required technical specifications. Geotextile reinforcement should be placed horizontally to the required length/width behind. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad _ March 13, 2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 40 The strong axis of the geotextile reinforcement should be placed perpendicular to the wall alignment if uniaxial geogrid is used. Structural Setbacks from Existing and Proposed Segmental Retaining Walls It is recommended that settlement-sensitive structures be built behind a 1:1 (h:v) projection above the heel of the foundation forthe segmental wall. In addition, all footings should be setback behind a 1:1 projection from the heel ofthe geogrid reinforced zone. If structures are located between the two 1:1 projections, the segmented wall should be designed to accommodate the additional surcharge loading from the structure, and deepened building footings may be required depending on the height ofthe segmental wall. All appurtenant structures (i.e., A/C pads, screen walls, light standards, pools, spas, etc.) should be placed outside a 1:1 (h:v) projection upward from the heel ofthe wall. GSI recommends that grid reinforcement is not placed beneath spas, pools, or other significant appurtenant structures. Alternately, footings may be constructed such that bearing surfaces are below the 1:1 projection. Appurtenant structures, including pools, utilities, and landscaping, should not disrupt the geogrid behind the walls. All structures proposed within the setback zone will be subject to both horizontal and vertical deflections and potential distressed. All construction proposed within the setback area should be reviewed by the design civil engineer and geotechnical consultant. This review should be provided in writing to the Client prior to installation in the field. Homeowners and all interested parties should be notified of the setback zones. Review of Segmental Retaining Wall Plans and Structural Calculations A qualified geotechnical consultant should review all proposed segmental retaining walls for global stability. Segmental retaining walls must meet City, local code, and slope stability factors-of-safety of 1.5 and 1.1 for static and seismic conditions, respectively. Criteria for residential use (limitations of land use) within geotextile reinforced backfill areas should be provided by the wall designer and reviewed by both the Client and the project geotechnical, and civil consultants. These limitations should be disclosed to all interested/affected parties. Soil Expansion The available data indicates that primarily very low to low expansive soils are present onsite. Although unlikely, it is possible that medium expansive soils may be encountered, locally. Lateral pressures due to expansive soil conditions can be provided on request, or the effect of expansive soil may be minimized by using select backfill (E.I. less than 20, Plasticity Index less than 6, and a maximum of 10 percent fines passing the No. 200 sieve) within the active zone, behind the wall. The active zone is generally defined as the area above a 1:1 projection up and away from the heel ofthe wall footing. The actual slope of the projection is based on the friction angle ofthe soil and the slope ofthe backfill behind the wall. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GeoSollS, InC. Page 41 Other Considerations Surcharge loads (slopes, traffic, etc.) should be applied by the design engineer as necessary. GSI recommends that geotextile reinforcement is not placed beneath appurtenant structures or improvements that require significant excavation that could damage the geotextile reinforcement. Appurtenant structures, should not disrupt the geotextile reinforcement behind the walls. Relatively deep underground utilities (i.e., greater than 2 to 3 feet in depth) should be located above a iy2:1 (h:v) projection down and away from the rear of the uppermost layer of geotextile reinforcement such that any future trenching for repairs would not damage the geotextile reinforcement. All structures proposed within the setback zones will be subject to both horizontal and vertical deflections and potential distress. All construction proposed within the setback area should be reviewed by the design civil engineer and geotechnical consultant. This review should be provided in writing to the Client, prior to installation in the field. The alternative use of paver stone flatwork should be considered where Portland Cement Concrete (PCC) concrete hardscape (walkways, patios, etc.) are planned above a 1:1 (h:v) projection up from the heel of segmental retaining walls. Paver stone flatwork is more capable of tolerating the ground deformations related to segmental retaining walls. Wall drainage should be reviewed by this office as plans become available. The gravel pad provided for the support of the base course should be adequately drained. • As with any settlement-sensitive structure, setbacks from adjacent descending slopes should be included in the wall design. A setback (lateral distance) equivalent to H/3 (where H is the height ofthe slope) should be provided for top of slope improvements. The setback should minimally be 7 feet and need not be greater than 40 feet. A setback (lateral distance) equivalent to H/2 (where H is the height of the slope) should be provided from the outside bottom edge ofthe wall for toe of slope improvements. The setback need not be more than 15 feet for these conditions. • Periodic testing of earth materials will be recommended in order to evaluate that soils with the minimum strength parameters are provided during construction ofthe walls. Additional Testing The parameters provided are preliminary, as exact wall locations, design, and the nature of earth materials used in wall construction are determined, additional testing during Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carisbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 42 earthwork is recommended in order to evaluate and/or modify the preliminary design values used. TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS AND EXPANSIVE SOILS Expansive Soils and Slope Creep Some ofthe 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 7 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 ofthe proposed improvements. The dessication/swelling and creep discussed above continues over the life of the improvements, and generally becomes progressively worse. Accordingly, the developer should provide this information to all interested/affected parties. Top of Slope Walls/Fences Due to the potential for slope creep for slopes higher than about 7 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 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 ofthe project structural engineer, and include the utilization ofthe following geotechnical parameters: Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carisbad _ March 13,2013 Flle:e:\wp12\6500\6524a.pge GeoSollS, InC. Page 43 Creep Zone: 5-foot vertical zone below the slope face and projected upward parallel to the slope face. Creep Load: 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. Point of Fixity: Located a distance of 1.5 times the caisson's diameter, below the creep zone. Passive Resistance: 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 ofthe creep prone zone above the point of fixity, to passive resistance, should be disregarded. Allowable Axial Capacity: Shaft capacity : 350 psf applied below the point of fixity over the surface area of the shaft. Tip capacity: 4,500 psf. EXPANSIVE SOILS, DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS Some ofthe 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 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 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. The moisture content ofthe subgrade should be proof tested within 72 hours priorto pouring concrete. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 44 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, y2 to % 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. 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. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 45 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 in 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 (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. PRELIMINARY ASPHALTIC CONCRETE PAVEMENT DESIGN RECOMMENDATIONS General The City of Carlsbad may retain the authority to approve the final structural design sections after subgrade elevations and actual resistance values (R-values) have been obtained at the conclusion of earthwork. Based on an assumed R-value of 20, a review of City of Carlsbad (2012), and for estimation and bidding purposes, the asphaltic concrete pavement section for the planned cul-de-sac street, provided herein, should be considered for preliminary design. Typically, actual pavement sections will likely vary, therefore final pavement sections should be based on actual R-value testing performed following the backfill of underground utilities in the street right-of-way. The preliminary pavement sections presented in the following table are based on the general Traffic Index (T.I.), utilized bythe Cityof Carlsbad for a residential cul-de-sac street, and the guidelines presented in the latest revision to the California Department of Transportation "Highway Design Manual" fifth edition. Based on an assumed R-value of 20 and a T.I. of 4.5 (City of Carlsbad, 2012), the following preliminary asphaltic concrete pavement designs are presented. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 46 STREET CLASSIFICATION TRAFFIC INDEX (T.I.)<1> STANDARD PAVEMENT DESIGNS STREET CLASSIFICATION TRAFFIC INDEX (T.I.)<1> R-VALUE AC* INCHES CLASS 2 AGGREGATE BASE <2> INCHES Street "A" Cul-De-Sac 4.5 20 3.0 6.0 ^ City of Carlsbad (2012). ^ Assumed R-values for Class 2 aggregate base R = 78 - Cal-Trans standard Class 2 Aggregate Base. The preliminary pavement section provided above is 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 T.I. 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 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 street and parking areas, all surficial deposits of loose soil material should be removed and recompacted 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 ofthe 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 obsen/ed by the project geotechnical consultant. Kraemer Land, Inc. APNs 156-200-01, -02, & File:e:\wp12\6500\6524a.pge 15, Carlsbad GeoSoils, Inc. w.o. 6524-A-SC March 13, 2013 Page 47 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 aggregate base and/or subbase course. 2. Traffic is not routed over completed base before paving 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 ofthe 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, enclosed 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. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad ^ March 13,2013 File:e:\wp12\6500\6524a.pge GeoSoilS, IttC. Page 48 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. ONSITE INFILTRATION-RUNOFF RETENTION SYSTEMS General Based on our review of LE&S (2013) onsite infiltration-runoff retention systems (OIRRS) are planned for Best Management Practices (BMP's) or Low Impact Development (LID) principles for the project. To that end, some guidelines should/must be followed in the planning, design, and construction of such systems. Such facilities, if improperly designed or implemented without consideration ofthe geotechnical aspects of site conditions, 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. A key factor in these systems is the infiltration rate (often referred to as the percolation rate) which can be ascribed to, or determined for, the earth materials within which these systems are installed. Additionally, the infiltration rate ofthe designed system (which may include gravel, sand, mulch/topsoil, or other amendments, etc.) will need to be considered. The project infiltration testing is very site specific, any changes to the location of the proposed OIRRS and/or estimated size of the OIRRS, may require additional infiltration testing. GSI anticipates that relatively impermeable earth materials including paralic deposits as well as expansive fill soils will be exposed at the conclusion of grading. Some ofthe methods which are utilized for onsite infiltration include percolation basins, dry wells, bio-swale/bio-retention, permeable pavers/pavement, infiltration trenches, filter boxes and subsurface infiltration galleries/chambers. Some of these systems are constructed using native and import soils, perforated piping, and filter fabrics while others employ structural components such as stormwater infiltration chambers and filters/separators. Every site will have characteristics which should lend themselves to one or more of these methods; but, not every site is suitable for OIRRS. In practice, OIRRS are usually initially designed bythe project design civil engineer. Selection of methods should include (but should not be limited to) review by licensed professionals including the geotechnical engineer, hydrogeologist, engineering geologist, project civil engineer, landscape architect, environmental professional, and industrial hygienist. Applicable governing agency requirements should be reviewed and included in design considerations. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad _ March 13, 2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 49 The following geotechnical guidelines should be considered when designing onsite infiltration-runoff retention systems: • On a preliminary basis, the onsite soils are considered to fall into Hydrologic Soil Group (HSG) "D" as deftned in County of San Diego (2007). • It is not good engineering practice to allow water to saturate soils, especially near slopes or improvements; however, the controlling agency/authority is now requiring this for OIRRS purposes on many projects. • If infiltration is planned, infiltration system design should be based on actual infiltration testing results/data, preferably utilizing double-ring infiltrometer testing (ASTM D 3385) to determine the infiltration rate of the earth materials being contemplated for infiltration. Wherever possible, infiltration systems should not be installed within ±50 feet ofthe tops of slopes steeper than 15 percent or within H/3 from the tops of slopes (where H equals the height of slope). Wherever possible, infiltrations systems should not be placed within a distance of H/2 from the toes of slopes (where H equals the height of slope). Impermeable liners and subdrains should be used along the bottom of bioretention swales/basins located within the influence of slopes. The landscape architect should be notified of the location of the proposed OIRRS. If landscaping is proposed within the OIRRS, consideration should be given to the type of vegetation chosen and their potential effect upon subsurface improvements (i.e., some trees/shrubs will have an effect on subsurface improvements with their extensive root systems). Over-watering landscape areas above, or adjacent to, the proposed OIRRS could adversely affect performance ofthe system. • Areas adjacent to, or within, the OIRRS that are subject to inundation should be properly protected against scouring, undermining, and erosion, in accordancewith the recommendations of the design engineer. Seismic shaking may result in the formation of a seiche which could potential overtop the banks of an OIRRS and result in down-gradient flooding and scour. If subsurface infiltration galleries/chambers are proposed, the appropriate size, depth interval, and ultimate placement ofthe detention/infiltration system should be evaluated by the design engineer, and be of sufficient width/depth to achieve optimum performance, based on the infiltration rates provided. In addition, proper debris filter systems will need to be utilized for the infiltration galleries/chambers. Debris filter systems will need to be self cleaning and periodically and regularly Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GCOSoilS, InC. Page 50 maintained on a regular basis. Provisions for the regular and periodic maintenance of any debris filter system is recommended and this condition should be disclosed to all interested/affected parties. Infiltrations systems should not be installed within ±8 feet of building foundations utility trenches, and walls, or a 1:1 (h:v) slope (down and away) from the bottom elements of these improvements. Alternatively, deepened foundations and/or pile/pier supported improvements may be used. Infiltrations systems should not be installed adjacent to pavement and/or hardscape improvements. Alternatively, deepened/thickened edges and curbs and/or impermeable liners may be utilized in areas adjoining the OIRRS. As with any OIRRS, localized ponding and groundwater seepage should be anticipated. The potential for seepage and/or perched groundwater to occur after site development should be disclosed to all interested/affected parties. Installation of infiltrations systems should avoid expansive soils (E.I. >51) or soils with a relatively high plasticity index (P.l. > 20). Infiltration systems should not be installed where the vertical separation of the groundwater level is less than ±10 feet from the base ofthe system. Where permeable pavements are planned as part of the system, the site Traffic Index (T.I.) Should be less than 25,000 Average Daily Traffic (ADT), as recommended in Allen, et al. (2011). Infiltration systems should be designed using a suitable factor of safety (FOS) to account for uncertainties in the known infiltration rates (as generally required bythe controlling authorities), and reduction in performance overtime. As with any OIRRS, proper care will need to be provided. Best management practices should be followed at all times, especially during inclement weather. Provisions for the management of any siltation, debris within the OIRRS, and/or overgrown vegetation (including root systems) should be considered. 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 ofthe filter media (e.g., sand, gravel, filter fabrics, topsoils, mulch, etc.) or other components utilized in construction, so that the design life exceeds 15 years. Due to the potential for piping and adverse seepage conditions, a burrowing rodent control program should also be implemented onsite. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13,2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 51 All or portions of these systems may be considered attractive nuisances. Thus, consideration ofthe effects of, or potential for, vandalism should be addressed. • Newly established vegetation/landscaping (including phreatophytes) may have root systems that will influence the performance of the OIRRS or nearby LID systems. • The potential for surface flooding, in the case of system blockage, should be evaluated by the design engineer. Any proposed utility backfill materials (i.e., inlet/outlet piping and/or other subsurface utilities) located within or near the proposed area of the OIRRS may become saturated. This is due to the potential for piping, water migration, and/or seepage along the utility trench line backfill. If utility trenches cross and/or are proposed near the OIRRS, cut-off walls or other water barriers will need to be installed to mitigate the potential for piping and excess water entering the utility backfill materials. Planned or existing utilities may also be subject to piping of fines into open-graded gravel backfill layers unless separated from overlying or adjoining OIRRS by geotextiles and/or slurry backfill. The use of OIRRS above existing utilities that might degrade/corrode with the introduction of water/seepage should be avoided. A vector control program may be necessary as stagnant water contained in OIRRS may attract mammals, birds, and insects that carry pathogens. Plan Specific LE&S (2013) indicates that onsite storm water will be treated using permeable brick pavers. If not properly designed, this type of system has the potential to introduce water into the pavement subgrade which can lead to subgrade failure and distress to the pavement. The following recommendations have been provided to help reduce this potential: 1. The permeable brick paver section should be constructed in accordance with County of San Diego (2007) guidelines. 2. The subgrade for the permeable brick paver section should be scarified at least 12 inches, moisture conditioned to at least the soil's optimum moisture content, and then be recompacted to at least 95 percent of the laboratory standard (ASTM D 1557). The subgrade should be sloped a minimum of 1 percent toward the approved outlet. 3. Following subgrade preparation, a subgrade enhancement geotextile (Tencate HP570) should be placed on the approved subgrade. The geotextile should be lapped up the sides of the pavement section excavation at least 4 to 6 inches. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13, 2013 File;e;\wp12\6500\6524a.pge GeoSoilS, InC. Page 52 4. A layer of filter fabric should be placed between the leveling sand and the open-grade rock to reduce the migration of fines into the rock layer. The rock and the leveling sand should be vibrated in place. 5. Owing to the HSG Type "D" conditions, a 4-inch diameter perforated drain pipe (Schedule 40 or approved equivalent) with perforations oriented downward should placed above the subgrade enhancement geotextile to collect and convey the infiltrated water toward the approved outlet. The perforated drain pipe should be sleeved with filter fabric material. 6. Concrete cut off walls should be constructed at the transition between the permeable brick paver section and any asphaltic concrete or PCC pavement section. The cut off walls should be at least 6 inches wide and extend at least 6 inches below the bottom of the permeable brick paver section. The purpose of the cut off walls is to reduce the lateral migration of infiltrated water into adjacent pavement structural sections. 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 ofthe fill soils which results in slow downslope movement. This type of movement is expected to occur throughout the life ofthe 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 adopted California Building Code), 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 Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13, 2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 53 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 adversely affects site improvements, and causes perched groundwater conditions. Graded slopes constructed utilizing 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 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 each homeowner. 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, site drainage should conform to Section 1804.3 of the 2010 CBC. Consideration should be given to avoiding construction of planters adjacent to structures (buildings, pools, spas, etc.). 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 ufllizedto 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. Kraemer Land, Inc. ~ W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad _ March 13, 2013 File:e:\wp12\6500\6524a.pge GeoSoilS, InC. Page 54 Toe of Slope Drains/Toe Drains Where signiflcant slopes intersect pad areas, surface drainage down the slope allows for some seepage into the subsurface materials, sometimes creating condiflons causing or contributing to perched and/or ponded water. Toe of slope/toe drains may be beneflcial in the mitigation of this condition due to surface drainage. The general criteria to be utilized by the design engineer for evaluating the need for this type of drain is as follows: • Is there a source of irrigation above or on the slope that could contribute to saturation of soil at the base of the slope? Are the slopes hard rock and/or impermeable, or relatively permeable, or; do the slopes already have or are they proposed to have subdrains (i.e., stabilization flils, etc.)? Are there cut-fill transitions (i.e., flll over bedrock), within the slope? Was the lot at the base of the slope overexcavated or is it proposed to be overexcavated? Overexcavated lots located at the base of a slope could accumulate subsurface water along the base ofthe flll cap. Are the slopes north facing? North facing slopes tend to receive less sunlight (less evaporation) relative to south facing slopes and are more exposed to the currently prevailing seasonal storm tracks. What is the slope height? It has been our experience that slopes with heights in excess of approximately 10 feet tend to have more problems due to storm runoff and irrigation than slopes of a lesser height. • Do the slopes "toe out" into a residential lot or a lot where perched or ponded water may adversely impact its proposed use? Based on these general criteria, the construction of toe drains may be considered by the design engineer along the toe of slopes, or at retaining walls in slopes, descending to the rear of such lots. Following are Detail 4 (Schematic Toe Drain Detail) and Detail 5 (Subdrain Along Retaining Wall Detail). Other drains may be warranted due to unforeseen condiflons, homeowner irrigation, or other circumstances. Where drains are constructed during grading, including subdrains, the locations/elevations of such drains should be sun/eyed, and recorded on the flnal as-built grading plans by the design engineer. It is recommended thatthe above be disclosed to all interested parties, including homeowners and any homeowners association. Kraemer Land, Inc. W O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad GcoSoilsInC. March 13, 2013 File:e:\wp12\6500\6524a.pge ' * Page 55 Drain pipe Permeable material 42 inches Drain may be constructed into, or at, the toe-of-slope 24-inch minimum 1. Soil cap compacted to 90 percent relative compaction. 2. Permeable material may be gravel wrapped in filter fabric (Mirafi MON or equivalent). 3. 4-inch-diameter, perforated pipe (SDR-35 or equivalent) with perforations down. 4. Pipe to maintain a minimum 1 percent fall. 5. Concrete cut-off wall to be provided at transition to solid outlet pipe. 6. Solid outlet pipe to drain to approved area. 7. Cleanouts are recommended at each property line. GeoSoitSf lnc. SCHEMATIC TOE DRAIN DETAIL Detail 4 2=1 (H:V) slope (typical) Backfill with compacted native soils Top of wall Retaining wall ^ Finish grade Wall footing Mirafi 140 filter fabric or equivalent ^-inch crushed gravel 4-inch drain 1/2 to 1 inch NOTES: 1. 2. 3. 4. 5. 6. 7. 8. Soil cap compacted to 90 percent relative compaction. Permeable material may be gravel wrapped in filter fabric (Mirafi MON or equivalent). 4-inch-diameter, perforated pipe (SDR-35 or equivalent) with perforations down. Pipe to maintain a minimum 1 percent fall. Concrete cut-off wall to be provided at transition to solid outlet pipe. Solid outlet pipe to drain to approved area. Cleanouts are recommended at each property line. Effort to compact should be applied to drain rock. GeoSoilSf Jji€« SUBDRAIN ALONG RETAINING WALL DETAIL Detail 5 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. 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 adjacent to proposed structures be eliminated for a minimum distance of 10 feet. As an alternaflve, closed-bottom type planters could be ufllized. 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 barrierto prevent penetraflon of irrigaflon water into the subgrade. Provisions should be made to drain the excess irrigaflon waterfrom the planters without saturating the subgrade below or adjacent to the planters. Graded slope areas should be planted with drought resistant vegetaflon. Consideration should be given to the type of vegetaflon chosen and their potenflal 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 compacflon. Gutters and Downspouts As previously discussed in the drainage secflon, the installation of gutters and downspouts should be considered to collect roof water that may othenwise inflltrate the soils adjacent to the structures. If ufllized, 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 flnal design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater condiflons along zones of contrasting permeabilifles may not be precluded from occurring in the future due to site irrigation, poor drainage condiflons, or damaged utilifles, and should be anflcipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide Kraemer Land, Inc. ~ W.O. 6524-A-SC APNs 156-200-01,-02, &-15, Carlsbad GeoSoilsInC. March 13, 2013 File:e:\wp12\6500\6524a.pge ' ' Page 58 the appropriate recommendaflons to mitigate the observed groundwater condiflons. Groundwater condiflons may change with the introducflon of irrigation, rainfall, or other factors. 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 construcflon of said improvements could be provided upon request. Pools and/or spas should not be constructed without specific design and construction recom mendations from GSI, and this construction recommendation should be provided to all interested/affected parties. This office should be notifled in advance of any flll placement, grading ofthe site, or trench backfllling after rough grading has been completed. This includes any grading, ufllity trench and retaining wall backfllls, flatwork, etc. Tile Flooring Tile flooring can crack, reflecting cracks in the concrete slab below the flle, although small cracks in a conventional slab may not be signiflcant. Therefore, the designer should consider addiflonal steel reinforcement for concrete slabs-on-grade where tile will be placed. The flle installer should consider installaflon methods that reduce possible cracking of the flle 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 notifled in advance of any flll placement, supplemental regrading of the site, or trench backfllling 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 backfllls. Footing Trench Excavation All fooflng excavations should be observed by a representative of this flrm subsequent to trenching and prior to concrete form and reinforcement placement. The purpose ofthe 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 fooflng or removal and recompaction ofthe subgrade materials would be recommended at that flme. Footing trench spoil and any excess soils generated from utility trench excavaflons should be compacted to a minimum relative compaction of 90 percent, if not removed from the site. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad GeoSoilS InC March 13, 2013 File:e:\wp12\6500\6524a.pge ' * Page 59 Trenching/Temporary Construction Backcuts Considering the nature ofthe onsite earth materials, it should be anflcipated 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 speciflcally superceded within the text of this report]), should be anflcipated. 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 recommendaflons should be provided to any contractors and/or subcontractors, or homeowners, etc., that may perform such work. Utility Trench Backfill 1. All interior ufllity trench backfill should be brought to at least 2 percent above opflmum moisture content and then compacted to obtain a minimum relaflve compaction of 90 percent ofthe 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 tesflng 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. Ufllifles 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 fooflng or grade beam in accordance with the recommendations ofthe structural engineer. SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend that observation and/or tesflng be performed by GSI at each of the following construction stages: • During grading/recertiflcation. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad GeoSoilS InC March 13, 2013 File:e:\wp12\6500\6524a.pge ' * Page 60 During excavation. During placement of subdrains or other subdrainage devices, prior to placing fill and/or backfill. After excavaflon of building fooflngs, retaining wall fooflngs, and free standing walls footings, prior to the placement of reinforcing steel or concrete. Prior to pouring any slabs or flatwork, after presoaking/presaturaflon 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 installaflon, priorto backfill placement. During placement of backflll for area drain, interior plumbing, utility line trenches, and retaining wall backflll. During slope construction/repair. When any unusual soil condiflons are encountered during any construction operations, subsequent to the issuance of this report. When any homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed, prior to construcflon. 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 documentaflon 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 recommendaflons 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/foundaflon and/or slab designer should provide recommendaflons 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 installaflon of the type of flooring materials typically used forthe particular applicaflon. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad GeoSoilS InC. March 13, 2013 File:e:\wp12\6500\6524a.pge ' ' Page 61 The structural engineer/designer should analyze actual soil-structure interaction and consider, as needed, bearing, expansive soil influence, and strength, stiffness and deflecflons in the various slab, foundation, and other elements in order to develop appropriate, design-speciflc details. As condiflons 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 criflcal 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 quesflons or requires further assistance, they should not hesitate to call or othenwise transmit their requests to GSI. In order to miflgate potenflal distress, the foundaflon and/or improvement's designer should conflrm to GSI and the governing agency, in wriflng, that the proposed foundaflons and/or improvements can tolerate the amount of differential settlement and/or expansion characteristics and other design criteria specifled herein. PLAN REVIEW Final project plans (grading, precise grading, foundaflon, retaining wall, landscaping, etc.), should be reviewed by this office prior to construcflon, so that construction is in accordance with the conclusions and recommendations of this report. Based on our review, supplemental recommendaflons and/or further geotechnical studies may be warranted. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative ofthe area; however, soil and bedrock materials vary in character between excavaflons and natural outcrops or condiflons 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 recommendaflons 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 tesflng performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendaflons have been properly implemented. Use of this report constitutes an agreement and consent bythe user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addiflon, this report may be subject to review by the controlling authorities. Thus, this report brings to completion our scope of services for this portion ofthe project. All samples will be disposed of after 30 days, unless specifically requested by the client, in wriflng. Kraemer Land, Inc. W.O. 6524-A-SC APNs 156-200-01, -02, & -15, Carlsbad GeoSoilS, InC. March 13, 2013 File:e:\wp12\6500\6524a.pge Page 62 GSI LEGEND — ARTIFICIAL FILL - UNDOCUMENTED — QUATERNARY PARALIC DEPOSITS. CIRCLED WHERE BURIED — APPROXIMATE LOCATION OF GEOLOGIC CONTACT — APPROXIMATE LOCATION OF EXPLORATORY TEST PIT APPROXIMATE LOCATION OF HAND-AUGER BORING, WITH TOTAL DEPTH IN FEET WO 156-200-16 ALL LOCATIONS ARE APPROXIMATE This document or eff/e is not a part of the Construction Documents and should not be relied upon as being an accurate depiction of design. Gco^^llite, GEOTECHNICAL MAP Plate 1 w.o. 6524-A-SC DATE: 03/13 SCALE: 1" = 50' APPENDIX A REFERENCES GeoSoils, Inc. APPENDIX A REFERENCES American Concrete Institute (ACI) Committee 318, 2008, Building code requirements for structural concrete (ACI318-08) and commentary, dated January. American Concrete Institute (ACI) Committee 302,2004, Guide for concrete floor and slab construcflon, ACI 302.1 R-04, dated June. Allen, v., Connerton, A., and Carlson, C, 2011, Introducflon to Inflltraflon Best Management Pracflces (BMP), Contech Construction Products, Inc., Professional Development Series, dated December. American Society for Testing and Materials (ASTM), 2003, Standard test method for inflltraflon rate of soils in fleld using double-ring infiltrometer, Designaflon D 3385-03, dated August. ,1998, Standard practice for installaflon of water vapor retarder used in contact with earth or granular flll under concrete slabs, Designaflon: E 1643-98 (Reapproved 2005). , 1997, Standard speciflcation for plastic water vapor retarders used in contact with soil or granular fill under concrete slabs, Designaflon: E 1745-97 (Reapproved 2004). American Society of Civil Engineers, 2006, Minimum design loads for buildings and other structures, ASCE Standard ASCE/SEI 7-05. Blake, Thomas 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 acceleraflon from California historical earthquake catalogs; Updated to December 2011, Windows 95/98 version. Bozorgnia, Y., Campbell K.W., and Niazi, M., 1999, Vertical ground motion: Characterisflcs, relationship with horizontal component, and building-code implications; Proceedings of the SMIP99 seminar on utilizaflon 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, 2010, California building code. GeoSoils, Inc. California Department of Water Resources, 1993, Division of Safety of Dams, Guidelines forthe 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. City of Carlsbad, 2012, Engineering standards. Vol. 1, general design standards, latest revision dated, November 21. County of San Diego, Department of Planning and Land Use, 2007, Low impact development (LID) handbook, stormwater management strategies, dated December 31. Hydrologic Solutions, StormChamber™ installaflon brochure, pgs. 1 through 8, undated. International Conference of Building Officials, 2001, California building code, California code of regulaflons tifle 24, part 2, volume 1 and 2. , 1998, Maps of known acflve fault near-source zones in California and adjacent portions of Nevada. Jennings, C.W., 1994, Fault acflvity map of California and adjacent areas: California Division of Mines and Geology, Map Sheet No. 6, scale 1:750,000. Kanare, H.M., 2005, Concrete floors and moisture. Engineering Bullefln 119, Portland Cement Association. Kennedy, M.P., and Tan, SS., 2005, Geologic map ofthe 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/preliminary_geologic_maps.html Lundstrom Engineering and Surveying, Inc., 2013, Preliminary tentative map, Buena Vista 11, City of Carlsbad, California, Sheet Cl, 40-scale, electronicallytransmittedtoGSI on March 11. Romanoff, M., 1957, Underground corrosion, originally issued April 1. Seed, 2005, Evaluation and mitigaflon of soil liquefaction hazard "evaluation of field data and procedures for evaluating the risk of triggering (or inception) of liquefacflon", in Geotechnical earthquake engineering; short course, San Diego, California, April 8-9. Sowers and Sowers, 1979, Unified soil classiflcation system (After U. S. Waterways Experiment Station and ASTM 02487-667) in Introductory Soil Mechanics, New York. Kraemer Land, Inc. GeoSoilS, Inc. Appendix A File:e:\wp12\6500\6524a.pge Page 2 state of California, 2013, Civil Code, Secflons 895 et seq. State of California Department of Transportation, Division of Engineenng 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, Landslide hazard identiflcation map no. 35, Plate 35A, Department of Consen/aflon, Division of Mines and Geology, DMG Open File Report 95-04. United States Geological Survey, 2011, Seismic hazard curves and uniform hazard response spectra - v5.1.0, dated February 2 , 1997, San Luis Rey quadrangle, San Diego County, California, 7.5 minute series, 1:24,000 scale. Kraemer Land, Inc. GeoSoilS, InC. Appendix A File;e:\wp12\6500\6524a.pge Page 3 APPENDIX B BORING LOGS GeoSoils, Inc. UNIFIED SOIL CLASSIFICATION SYSTEM CONSISTENCY OR RELATIVE DENSITY Major Divisions Group Symbols Typical Names CRITERIA > in o o CJ d c o "C c CO 03 o CO TS la c •« O iS o c CO o 2 !=: 03 o o _ 03 t o 03 Z o m in (5? £ « 03 in o CJ GW Well-graded gravels and gravel- sand mixtures, little or no fines standard Penetration Test o GP Poorly graded gravels and gravel-sand mixtures, little or no fines •*-' (5 GM Silty gravels gravel-sand-silt mixtures GC Clayey gravels, gravel-sand-clay mixtures SW Well-graded sands and gravelly sands, little or no fines (0 "2 K 5 O CO Penetration Resistance N (blows/ft) Relative Density 0-4 Very loose 4-10 Loose 10-30 Medium 30-50 Dense > 50 Very dense SP Poorly graded sands and gravelly sands, littie or no fines in SIVI Silty sands, sand-silt mixtures CO SC Clayey sands, sand-clay mixtures ML 03 > in o o _2 CM CO §• "S « 03 0 .E w fl) £ JS E "> O J » •g 2 o m o —' m CO Inorganic silts, very fine sands, rocic flour, silty or clayey fine sands standard Penetration Test 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 MH "g -g £ cn 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 Penetration Resistance N (blows/ft) Consistency Unconfined Compressive Strength (tons/ft^) <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 Highly Organic Soils PT Peat, mucic, and other highly organic soils 3/4" #4 #10 #40 #200 U.S. Standard Sieve Unified Soil Cobbles Gravel Sand Silt or Clay Classification Cobbles coarse fine coarse medium fine MOISTURE CONDITIONS Dry Absence of moisture; dusty, dry to the touch Slightly Moist Below optimum moisture content for compaction Moist Near optimum moisture content Very Moist Above optimum moisture content Wet Visible free water; below water table MATERIAL QUANTITY trace 0 - 5 % few 5-10% little 10-25% some 25 - 45 % OTHER SYMBOLS C Core Sample S SPT Sample B Bulk Sample T Groundwater 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. Flle:Mgr; c;\SoilClassif.wpd PLATE B-1 w.o. 6524-A-SC Kraemer Land Buena Vista 11 Subdivision Logged By: RBB February 25, 2013 LOG OF EXPLORATORY TEST PITS AND HAND AUGER BORINGS TEST PIT NO. ELEV. (ft.) DEPTH (ft.) GROUP SYMBOL SAMPLE DEPTH (ft.) MOISTURE (%) FIELD DRY DENSITY (pcf) DESCRIPTION TP-1 ±156 0-2 ML Composite Bulk® 0-4 QUATERNARY COLLUVIUM: SANDY SILT, dark aravish brown, moist, soft to stiff; porous, trace organics. 2-372 SC WEATHERED PARALIC DEPOSITS: CLAYEY SAND, strona brown, moist, dense; slightly porous. 372-472 CL/SC UND@4' 12.3 118.7 QUATERNARY PARALIC DEPOSITS: SANDY CLAY/CLAYEY SAND, strong brown and reddish brown, moist, hard/dense. UND = Undisturbed Total Depth = 472' No Groundwater/Caving Encountered Backfilled 2-25-2013 TP-2 ±157 0-2 SC QUATERNARY COLLUVIUM: CLAYEY SAND, dark qravish brown, dry, loose becoming medium dense with depth; porous, trace to locally abundant organics. 2-672 SC/CL WEATHERED PARALIC DEPOSITS: CLAYEY SAND/SANDY CLAY, reddish yellow, olive brown, and reddish brown, dry becoming moist with depth, medium dense/very stiff becoming dense/hard with depth; porous. 672-7 CL UND@7 13.2 116.0 QUATERNARY PARALIC DEPOSITS: SANDY CU^Y. reddish vellow. olive brown, and reddish brown, moist, hard. Total Depth = 7' No Groundwater/Caving Encountered Backfilled 2-25-2013 PLATE B-2 w.o. 6524-A-SC Kraemer Land Buena Vista 11 Subdivision Logged By: RBB February 25, 2013 LOG OF EXPLORATORY TEST PITS AND HAND AUGER BORINGS TEST PIT NO. ELEV. (ft.) DEPTH (ft.) GROUP SYMBOL SAMPLE DEPTH (ft.) MOISTURE (%) FIELD DRY DENSITY (pcf) DESCRIPTION TP-3 ±156 0-2 ML7CL QUATERNARY COLLUVIUM: SANDY SILT/SANDY CLAY, dark qravish brown, moist, medium stiff; porous, trace organics. TP-3 ±156 2-5 ML/CL UND @ 472 SM BAG @4-5 11.6 114.0 WEATHERED PARALIC DEPOSITS: SANDY SILT/SANDY CLAY, brown and olive brown, damp, hard; porous, trace manganese-oxide staining. TP-3 ±156 5-6 CL QUATERNARY PARALIC DEPOSITS: SANDY CLAY, reddish vellow, damp, hard; trace manganese-oxide staining. TP-3 Total Depth = 6' No Groundwater/Caving Encountered Backfilled 2-25-2013 TP-4 ±163 0-272 SP QUATERNARY COLLUVIUM: SAND with trace SILT, dark aravish brown, moist, loose; porous, abundant roots, trace cobble. TP-4 ±163 272-372 SM WEATHERED PARALIC DEPOSITS: SILTY SAND, liaht reddish yellow, damp, medium dense; porous. TP-4 ±163 372-5 SM/SC SM BAG @ 372-472 QUATERNARY PARALIC DEPOSITS: SILTY to CLAYEY SAND, reddish yellow, damp, very dense. TP-4 Total Depth = 5' No Groundwater/Caving Encountered Backfilled 2-25-2013 PLATE B-3 W.o. 6524-A-SC Kraemer Land Buena Vista 11 Subdivision Logged By: RBB February 25, 2013 LOG OF EXPLORATORY TEST PITS AND HAND AUGER BORINGS TEST PIT NO. ELEV. (ft.) DEPTH (ft.) GROUP SYMBOL SAMPLE DEPTH (ft.) MOISTURE (%) FIELD DRY DENSITY (pcf) DESCRIPTION TP-5 ±173 0-1 SM QUATERNARY COLLUVIUM: SILTY SAND, dark aravish brown, damp, loose; porous. TP-5 ±173 1-14 SM/SC UND @ 872 8.5 112.3 QUATERNARY PARALIC DEPOSITS: SILTY to CLAYEY SAND, reddish yellow, moist, dense. TP-5 Total Depth = 14' No Groundwater/Caving Encountered Backfilled 2-25-2013 HA-1 ±160 0-2 SM QUATERNARY COLLUVIUM: SILTY SAND, dark aravish brown, moist, loose; porous. HA-1 ±160 2-372 SM WEATHERED PARALIC DEPOSITS: SILTY SAND, dark vellowish brown, damp, medium dense; porous. HA-1 ±160 372-472 SC QUATERNARY PARALIC DEPOSITS: CLAYEY SAND, reddish vellow. moist, dense; trace manganese-oxide staining. HA-1 Total Depth = 472' No Groundwater/Caving Encountered Backfilled 2-25-2013 PLATE B-4 W.o. 6524-A-SC Kraemer Land Buena Vista 11 Subdivision Logged By: RBB February 25, 2013 LOG OF EXPLORATORY TEST PITS AND HAND AUGER BORINGS TEST PIT NO. ELEV. (ft.) DEPTH (ft.) GROUP SYMBOL SAMPLE DEPTH (ft.) MOISTURE (%) FIELD DRY DENSITY (pcf) DESCRIPTION HA-2 ±177 0-1 SP QUATERNARY COLLUVIUM: SAND with trace SILT, dark aravish brown, moist, loose; porous. HA-2 ±177 1-7 SM SM BAG @3-7 QUATERNARY PARALIC DEPOSITS: SILTY SAND, reddish vellow. moist, dense. HA-2 Total Depth = 7' No Groundwater/Caving Encountered Backfilled 2-25-2013 PLATE B-5 APPENDIX C SEISMICITY GeoSoils, Inc. EQFAULT Version 3.00 DETERI^INISTIC ESTTI^TION OF PEAK ACCELERATION FROM DIGITIZED FAULTS JOB NUMBER: 6524-A-SC ^^^^ DATE: 03-01-2013 JOB NAME: KRAEMER LAND, INC. CALCULATION NAME: 6524 FAULT-DATA-FILE NAME: C:\Program Fi1es\EQFAULTl\CGSFLTE.DAT SITE COORDINATES: SITE LATITUDE: 33.1683 SITE LONGITUDE: 117.3374 SEARCH RADIUS: 62.14 mi ATTENUATION RELATION: 11) Bozopgnia Campbell Niazi (1999) Hor.-Pleist. Soil-Cor. UNCERTAINTY (M=Median, S=sigma): S Number of Sigmas: 1.0 DISTANCE MEASURE: cdist SCOND: 1 , „ Basement Depth: .00 km Campbell SSR: 0 Campbell SHR: 0 COMPUTE PEAK HORIZONTAL ACCELERATION FAULT-DATA FILE USED: C:\Program Files\EQFAULTl\CGSFLTE.DAT MINIMUM DEPTH VALUE (km): 3.0 Page 1 W.O. 6524-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. NEWPORT-INGLEWOOD (Offshore) 5.7( 9.2) 7.1 0.573 X ROSE CANYON 6.2( 9.9) 7.2 0.571 X CORONADO BANK 21.8( 35.1) 7.6 0.265 IX ELSINORE (TEMECULA) 23.4( 37.7) 6.8 0.144 VIII ELSINORE (JULIAN) 23.7( 38.2) 7.1 0.174 VIII ELSINORE (GLEN IVY) 32.9( 52.9) 6.8 0.102 VII SAN JOAQUIN HILLS 34.8( 56.0) 6.6 0.119 VII PALOS VERDES 35.8( 57.6) 7.3 0.132 VIII EARTHQUAKE VALLEY 43.7( 70.4) 6.5 0.062 VI NEWPORT-INGLEWOOD (L.A.Basi n) 45.5( 73.3) 7.1 0.089 VII SAN JACINTO-ANZA 46.0( 74.0) 7.2 0.095 VII SAN JACINTO-SAN JACINTO VALLEY 46.4( 74.7) 6.9 0.076 VII CHINO-CENTRAL AVE. (Elsinore) 47.0( 75.6) 6.7 0.092 VII WHilliER 50.8( 81.8) 6.8 0.064 VI SAN JACINTO-COYOTE CREEK 52.0( 83.7) 6.6 0.055 VI ELSINORE (COYOTE MOUNTAIN) 58.2( 93.6) 6.8 0.056 VI SAN JACINTO-SAN BERNARDINO 59.0( 94.9) 6.7 0.051 VI PUENTE HILLS BLIND THRUST 60.8( 97.8) 7.1 0.093 VII -END OF SEARCH- 18 FAULTS FOUND WITHIN THE SPECIFIED SEARCH RADIUS. THE NEWPORT-INGLEWOOD (Offshore) FAULT IS CLOSEST TO THE SITE. IT IS ABOUT 5.7 MILES (9.2 km) AWAY. LARGEST MAXIMUM-EARTHQUAKE SITE ACCELERATION: 0.5726 g Page 2 W.O. 6524-A-SC Plate C-2 1100 1000 — 900 CALIFORNIA FAULT MAP KRAEMER LAND, INC. -400 -300 -200 -100 0 100 200 300 400 500 600 W.O. 6524-A-SC Plate C-3 C O cs I— o> u u < MAXIMUM EARTHQUAKES KRAEMER LAND, INC. .01 .001 i 1 j > 1 $ r -> n 1 1 1 ? is* 10 Distance (mi) 100 W.O. 6524-A-SC Plate C-4 EQSEARCH Version 3.00 ESTIMATION OF PEAK ACCELERATION FROM CALIFORNIA EARTHQUAKE CATALOGS JOB NUMBER: 6524-A-SC QJ_Q^_2013 JOB NAME: KRAEMER LAND, INC. EARTHQUAKE-CATALOG-FILE NAME: ALLQUAKE.DAT SITE COORDINATES: SITE LATITUDE: 33.1683 SITE LONGITUDE: 117.3374 SEARCH DATES: START DATE: 1800 END DATE: 2011 SEARCH RADIUS: 62.1 mi 100.0 km ATTENUATION RELATION: 11) Bozorgnia Campbell Niazi (1999) Hor.-Pleist. Soil-Cor, UNCERTAINTY (M=Median, s=sigma): S Number of sigmas: i.u ASSUMED SOURCE TYPE: SS [ss=Strike-slip, DS=Reverse-slip, BT=BlTnd-thrust] SCOND: 1 Depth source: A , -n r. Basement Depth: .00 km Campbell SSR: 0 Campbell SHR: 0 COMPUTE PEAK HORIZONTAL ACCELERATION MINIMUM DEPTH VALUE (km): 3.0 Page 1 W.O. 6524-A-SC Plate C-5 EARTHQUAKE SEARCH RESULTS Page 1 FILE LAT. LONG. DATE CODE NORTH WEST DMG 1 33. OOOO 117. 3000 11/22/1800 MGI 1 33. OOOO 117. OOOO 09/21/1856 MGI 32. 8000 117. 1000 05/25/1803 DMG 32. 7000 117. 2000 05/27/1862 PAS 32. 9710 117. 8700 07/13/1986 T-A 32. 6700 117. 1700 12/00/1856 T-A 32. 6700 117. 1700 10/21/1862 T-A 32 6700 117. 1700 05/24/1865 DMG 33 7000 117. 4000 05/15/1910 DMG 33 7000 117. 4000 04/11/1910 DMG 33 7000 117. 4000 05/13/1910 DMG 33 2000 116. 7000 01/01/1920 DMG 33 6990 117. 5110 05/31/1938 DMG 32 8000 116. 8000 10/23/1894 MGI 33 2000 116. 6000 10/12/1920 DMG 33 7100 116. 9250 09/23/1963 DMG 33 7500 117. OOOO 04/21/1918 DMG 33 7500 117. OOOO 06/06/1918 MGI 33 8000 117 6000 04/22/1918 DMG 33 5750 117 9830 03/11/1933 DMG 33 .6170 117 9670 03/11/1933 DMG 33 .8000 117 OOOO 12/25/1899 DMG 33 .6170 118 0170 03/14/1933 GSP 33 .5290 116 5720 06/12/2005 DMG 33 .9000 117 2000 12/19/1880 GSG 33 .4200 116 4890 07/07/2010 PAS 33 .5010 116 5130 02/25/1980 GSP 33 .5080 116 5140 10/31/2001 DMG 33 .5000 116 5000 09/30/1916 DMG 33 .0000 116 .4330 06/04/1940 DMG 33 .6830 118 .0500 03/11/1933 DMG 33 ,7000 118 .0670 03/11/1933 DMG 33 .7000 118 .0670 03/11/1933 DMG 34 .0000 117 .2500 07/23/1923 MGI 34 .0000 117 .5000 12/16/1858 DMG 33 .3430 116 .3460 04/28/1969 DMG 33 .7500 118 .0830 03/11/1933 DMG 33 .7500 118 .0830 03/11/1933 DMG 33 .7500 118 .0830 03/11/1933 DMG 33 .7500 118 .0830 03/13/1933 DMG 33 .7500 118 .0830 03/11/1933 GSG 33 .9530 117 .7610 07/29/2008 DMG 33 .9500 116 .8500 09/28/1946 DMG 33 .4000 116 .3000 02/09/1890 TIME 1 (UTC) 1 H M Seel DEPTH (km) QUAKE MAG. SITE ACC. g SITE MM INT. APPROX. DISTANCE mi [km] 2130 0.01 0.0 6.501 0.233 IX 11.8 ( 19.0) 730 0.01 0.0 5.00 0.048 VI 22.7( 36.5) 0 0 0.0 0.0 5.00 0.038 V 28.9( 46.5) 20 0 0.0 0.0 5.90 0.056 VI 33.3 ( 53.6) 1347 8.2 6.0 5.30 0.038 V 33.7( 54.2) 0 0 0.0 0.0 5.00 0.030 V 35.7( 57.5) 0 0 0.0 0.0 5.00 0.030 V 35.7( 57.5) 0 0 0.0 0.0 5.00 0.030 V 35.7( 57.5) 1547 0.0 0.0 6.00 0.053 VI 36.9( 59.4) 757 0.0 0.0 5.00 0.029 V 36.9( 59.4) 620 0.0 0.0 5.00 0.029 V 36.9( 59.4) 235 0.0 0.0 5.00 0.029 V 36.9( 59.4) 83455.4 10.0 5.50 0.038 V 38.0( 61.1) 23 3 0.0 0.0 5.70 0.040 V 40.2( 64.7) 1748 0.0 0.0 5.30 0.030 V 42.7( 68.7) 144152.6 16.5 5.00 0.024 V 44.3 ( 71.3) 223225.0 0.0 6.80 0.074 VII 44.6( • 71.8) 2232 0.0 0.0 5.00 0.024 V 44.6( 71.8) 2115 0.0 0.0 5.00 0.023 IV 46.2( • 74.3) 518 4.0 0.0 5.20 0.026 V 46.6( : 75.0) 154 7.8 0.0 6.30 0.049 VI 47.7( • 76.8) 1225 0.0 0.0 6.40 0.053 VI 47.7( : 76.8) 19 150.0 0.0 5.10 0.023 IV 49.9( ' 80.4) 154146.5 14.0 5.20 0.024 IV 50.7( • 81.6) 0 0 0.0 0.0 6.00 0.038 V 51.1( : 82.3) 235333.5 14.0 5.50 0.027 V 52.0( : 83.6) 104738.5 13.6 5.50 0.027 V 52.8( : 85.0) 075616.6 15.0 5.10 0.021 IV 53.0( : 85.2) 211 0.0 0.0 5.00 0.020 IV 53.5( : 86.0) 1035 8.3 0.0 5.10 0.021 IV 53.6( : 86.2) 658 3.0 0.0 5.50 0.026 V 54.3( : 87.4) 51022.0 0.0 5.10 0.020 IV 55.8( : 89.8) 85457.0 0.0 5.10 0.020 IV 55.8( : 89.8) 73026.0 0.0 6.25 0.039 V 57.6( : 92.8) 10 0 0.0 0.0 7.00 0.064 VI 58.2( : 93.6) 232042.9 20.0 5.80 0.029 v 58.5( : 94.1) 230 0.0 0.0 5.10 0.019 IV 58.8 : 94.6) 323 0.0 0.0 5.00 0.018 IV 58.8 [ 94.6) 910 0.0 0.0 5.10 0.019 IV 58.8 : 94.6) 131828.0 0.0 5.30 0.021 IV 58.8 : 94.6) 2 9 0.0 0.0 5.00 0.018 IV 58.8 : 94.6) 184215.7 14.0 5.30 0.021 IV 59.4 [ 95.6) 719 9.0 0.0 5.00 0.017 IV 60.8 C 97.9) 12 6 0.0 0.0 6.30 0.037 V 62.0 C 99.7) Page 2 W.O. 6524-A-SC Plate C-6 -END OF SEARCH- 44 EARTHQUAKES FOUND WITHIN THE SPECIFIED SEARCH AREA. TIME PERIOD OF SEARCH: 1800 TO 2011 LENGTH OF SEARCH TIME: 212 years THE EARTHQUAKE CLOSEST TO THE SITE IS ABOUT 11.8 MILES (19.0 km) AWAY. LARGEST EARTHQUAKE MAGNITUDE FOUND IN THE SEARCH RADIUS: 7.0 LARGEST EARTHQUAKE SITE ACCELERATION FROM THIS SEARCH: 0.233 g COEFFICIENTS FOR GUTENBERG & RICHTER RECURRENCE RELATION: a-value= 0.909 b-value= 0.364 beta-value= 0.837 TABLE OF MAGNITUDES AND EXCEEDANCES: Earthquake | Number of Times | cumulative Magnitude | Exceeded j No. / Year + + 4 0 I 44 I 0.20853 4 5 I 44 I 0.20853 5.0 I 44 I 0.20853 5.5 I 16 I 0.07583 6.0 I 9 I 0.04265 6.5 I 3 I 0.01422 7.0 1 1 I 0.00474 Page 3 W.O. 6524-A-SC Plate C-7 EARTHQUAKE EPICENTER MAP KRAEMER LAND, INC. 1100 1000 900 800 - 700 600 - 500 400 300 — 200 -- 100 -100 -400 -300 -200 -100 0 100 200 300 400 500 600 W.O. 6524-A-SC Plate C-8 (0 0) >- Ui c > LU 0) E z Qi > JS 3 E E o EARTHQUAKE RECURRENCE CURVE KRAEMER LAND, INC. 100 10 .1 .01 .001 t 4 ^ r ^ ' f } t 1 Illl MIL M 1,1, Illl LIM Illl Illl JJ-LL Illl Illl .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. 6524-A-SC Plate C-9 PSH Deaggregation on NEHRP D soil KRAEMER_LAND 117.337^ W, 33.168 N. Peak l loriz. Ground Accel.>-^0.4907 g Ann. Exceedance Rate .4()IH-03. Mean Return l ime 2475 years Mean (R.IVl,t'„) 14.8 km, 6.66, 1.06 Modal (R,M.eo) - 8.8 km, 6.79, 0.85 (from peak R.M bin) Modal (R,M,t *) 8.9 km, 6.79, 1 to 2 sigma (from peak R.M,e bin Binning: DeltaR 10. km, deltaM-0.2, Deltae-I.O I- O) > cn m o> o O Prob. SA, PGA <median(R,M) • eo<-2 -2<eo<-I -1 <Eo<-().5 -0.5 < £n < 0 >medlan 0<eo<0.5-^.^.'^- 0.5 < eo < I 1< Eo < 2 2 < £o < 3 200910 UPDATE 2013 Mar 1 03.11 56 Distance (R). magnitude (M). epsilon (EO.E) deaggregation for a site on soil with average vs= 300 m/s top 30 m. USGS CGHT PSHA2008 UPDATE Bins with H 0.05% contrib. omitted KRAEMER_LAND Geographic Deagg. Seismic Haz§j|f 8.4 for O.OO-s Spectral Accel, 0.4906 g PGA Exceedance Return Time: 2475 year Max. significant source distance 110. km. View angle is 35 degrees above horizon Gridded-source hazard accum. in 45*' intervals Soil site. Vs30(msN- 300.0 8.1 7.8 7.5 -7.2 6.9 -6.6 6.3 I 6.0 M > H m O • p tn ro 4^ L S(JS PSILt 2010ed O _ HL - O u =1 eo km 2013 Mar 1 03 11 56 Site Coords:-117.337 33 1683 (yellow disl<) Vs30= 300.0. Max annual ExcdRate .9476E-04 (column iieight prop, to ExRate). Red diamonds: historical earthquakes. M>6 PSH Deaggregation on NEHRP D soil KRAEMER_LAND 117.337^ W, 33.168 N. Peak Moriz. Ground Accel.>-0.2736 g Ann. Exceedance Rate .21 lE-()2. Mean Return Time 475 years Mean (R,M,t-,)) 25.6 km, 6.68, 0.59 Modal (R,M,e,)) 9.1 km, 6.65, -0.12 (from peak R.M bin) Modal (R,M,t*) 9.2 km. 6.65, 0 to 1 sigma (from peak R,M,F bin) Binning: DeltaR 10. km. deltaM-0.2, Deltai^-1.0 2013 Mar 1 03:15:25 Distance (R). magnitude (M). epsilon (E0,E) deaggregation for a site on soil with average vs= 300 m/s top 30 m. USGS CGHT PSHA2008 UPDATE Bins with It 0.05% contrib. omitted KRAEMER_LAND Geographic Deagg. Seismic Haz for O.OO-s Spectral Accel, 0.2736 g PGA Exceedance Return Time: 475 year Max. significant source distance 129. km. View angle is 35 degrees above horizon Gridded-source hazard accum. in 45'- intervals Soil site. Vs30(m/s)pf •0 r-> H m O p at Ul 300.0 M o 2013 Mar 1 03 15 25 Site Coords:-117.337 33.1683 (yellow disk) Vs30= 300.0. Max annual ExcdRate .28236-03 (column height prop, to ExRate). Red diamonds: historical earthquakes. M>6 APPENDIX D LABORATORY DATA GeoSoils, Inc. 60 50 LU 40 Q H 30 20 10 CL CH / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / • / / IVIL IVIH CL-I^L IVIL IVIH 1 1 IVIL IVIH 20 40 60 LIQUID LIMIT 80 100 Sample Depth/El. PL PI Fines USCS CLASSIFICATION • TP-3 4.0 37 19 18 62 SANDY LEAN CLAY(CL) GeoSoils, Inc. GeoSoils, Inc. 5741 Palmer Way Carlsbad, CA 92008 Telephone: (760)438-3155 Fax: (760)931-0915 ATTERBERG LIMITS' RESULTS Project: KRAEMER LAND, INC. Number: 6524-A-SC Date: March 2013 Plate: D -1 100 95 90 85 80 75 70 H65 C3 ^ 60 ^55 Cd in 50 ^45 §40 cc IU 0:35 30 25 20 15 10 U.S. SIEVE OPENING IN INCHES 6 •* 3 ^ 1.5 3/4 T U.S. SIEVE NUMBERS 310,416 20 30 40 50 go HYDROMETER V V '140 Tl 100 10 1 0.1 GRAIN SIZE IN MILLIMETERS 0.01 0.001 COBBLES GRAVEL SAND SILT OR CLAY COBBLES coarse fine coarse medium fine SILT OR CLAY Sample Depth Range Visual Classiflcation/USCS CLASSIFICATION LL PL PI Cc Cu • TP-3 4.0 4-5 SANDY LEAN CLAY(CL) 37 19 18 Sample Depth D100 D60 D30 D10 %Gravel %Sand %Silt %Clay TP-3 4.0 9.5 1.1 36.9 62.0 GeoSoils, Inc. 5741 Palmer Way GeoSoils, Inc. Carlsbad, CA 92008 Telephone: (760)438-3155 Fax: (760)931-0915 GRAIN SIZE DISTRIBUTION Project: KRAEMER LAND, INC. Number: 6524-A-SC Date: March 2013 Plate: D - 2 3,000 2,500 2,000 o. X H o Z UJ a. \-w a. S5 X CO 1,500 1,000 500 500 1,000 1,500 2,000 2,500 3,000 NORMAL PRESSURE, psf Sample Depth/El. Range Classification Primary/Residual Sample Type Yd MC% C <t> • TP-5 8.5 Clayey Sand Primary Shear Undisturbed 112.7 8.5 433 34 • TP-5 8.5 Residual Shear Undisturbed 112.7 8.5 366 30 Reshear Stiear Note: Sample Innundated Prior To Test GeoSoils, Inc. 5741 Palmer Way GeoSoils, Inc. Carlsbad, CA 92008 Telephone: (760)438-3155 Fax: (760)931-0915 DIRECT SHEAR TEST Project: KRAEMER LAND, INC. Number: 6524-A-SC Date: March 2013 Plate: D - 3 APPENDIX E GENERAL EARTHWORK AND GRADING GUIDELINES GeoSoils, Inc. GENERAL EARTHWORK AND GRADING GUIDELINES General These guidelines present general procedures and requirements for eartliwork and grading as sliown 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 supercede the 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 ofthe 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 Priorto 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 ofthe 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 bythe 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. GeoSoils, Inc. 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 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 Responsibilitv All clearing, site preparation, and earthwork performed on the project should be conducted bythe 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 ofthe geotechnical consultant, and to place, spread, moisture condition, mix, and compact the fill in accordance with the recommendations ofthe 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 ofthe 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 forthe 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 Kraemer Land, Inc. _ Appendix E File:e:\wp12\6500\6524a.pge GCOSoilS, InC. Page 2 removed priorto 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 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 (horizontal to vertical [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 ofthe lowest bench or key is also 15 feet, with the key founded on firm material, as designated bythe geotechnical consultant. As a general rule, unless specifically recommended otherwise bythe geotechnical consultant, the minimum width of fill keys should be equal to Va 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. Kraemer Land, Inc. _ Appendix E File:e:\wp12\6500\6524a.pge GcoSoilS, InC. Rage 3 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 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 bythe 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 bythe geotechnical consultant. Oversized material should be taken offsite, or placed in accordance with recommendations ofthe 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., greaterthan 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. Kraemer Land, Inc. _ Appendix E File:e:\wp12\6500\6524a.pge GcoSoilS, InC. Page 4 To facilitate future trenching, rock (or oversized material), should not be placed within the hold-down depth feet from finish grade, the range of foundation excavations, future utilities, or underground construction unless specifically approved bythe 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. 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 ofthe 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 ofthe 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 ofthe 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 Kraemer Land, Inc. _ Appendix E File:e:\wp12\6500\6524a.pge GcoSoilS, InC. Page 5 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 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. 2. 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 bythe project civil engineer. Drainage at the subdrain outlets should be provided by the project civil engineer. Kraemer Land, Inc. _ Appendix E File:e:\wp12\6500\6524a.pge GcoSoilS, InC. Page 6 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 othenwise approved, the cut portion ofthe slope should be observed bythe 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. 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 othenwise 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 bythe project civil engineer and should be constructed in compliance with the ordinances ofthe controlling governmental agencies, and/or in accordance with the recommendations ofthe 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 ofthe work, final reports should be submitted, and may be subject to review by the controlling governmental agencies. Nofurther excavation orfilling should be undertaken without prior notification ofthe 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. Kraemer Land, Inc. _ Appendix E File:e:\wp12\6500\6524a.pge GCOSoilS, InC. Page 7 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 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. Kraemer Land, Inc. _ Appendix E File:e:\wp12\6500\6524a.pge GCOSoilS, InC. Page 8 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 belowthe 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 ofthe fill as soon as possible following testing. The technician's vehicle should be parked at the perimeter ofthe 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 ofthe 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. Kraemer Land, Inc. _ Appendix E File:e:\wp12\6500\6524a.pge GCOSoilS, InC. Page 9 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 besubjectto 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. Kraemer Land, Inc. _ Appendix E Flle:e:\wp12\6500\6524a.pge GcoSoilS, InC. Page 10 Proposed grade Toe of slope as shown on grading plan Natural slope to be restored with compacted 2-foot minimum in bedrocic or rapproved eartin material r Backcut varies Bedrock or approved naiive material 15-foot minimum or —H/2 where H is— the slope height Subdrain as recommended by geotechnical consultant NOTES: 1. Where the natural slope approaches or exceeds the design slope ratio, special recommendations would be provided by the geotechnical consultant. 2. The need for and disposition of drains should be evaluated by the geotechnical consultant, based upon exposed conditions. GeoSoils, Ifie. FILL OVER NATURAL (SIDEHILL FILL) DETAIL Plate E-7 Cut/fill contact as shown on grading plan Proposed grade H = height of slope Subdrain as recommended by geotechnical consultant Bedrock or approved native material NOTE: The cut portion of the slope should be excavated and evaluated by the geotechnical consultant prior to construction of the fill portion. Geo$kfiiSf inc. FILL OVER CUT DETAIL Plate E-8 Natural slope Proposed finish grade Typical benching (4-foot minimum) Compacted stablization fill Bedrock or other approved native material If recommended by the geotechnical consultant, the remaining cut portion of the slope may require removal and replacement with compacted fill. Subdrain as recommended by geotechnical consultant NOTES: 1. Subdrains may be required as specified by the geotechnical consultant. 2 W shall be equipment width (15 feet) for slope heights less than 25 feet. For slopes greater than 25 feet, W shall be evaluated by the geotechnical consultant. At no time, shall W be less than H/2, where H is the height of the slope. GeoSo^t inc. STABLIZATION FILL FOR UNSTABLE MATERIAL EXPOSED IN CUT SLOPE DETAIL Plate E-9 Proposed finish grade Natural grade Bedrock or approved native material Typical benching (4-foot minimum) 2-foot minimum l<ey depth or H/2 if H>30 feet Subdrain as recommended by geotechnical consultant NOTES: 1. 15-foot minimum to be maintained from proposed finish slope face to backcut. 2. The need and disposition of drains will be evaluated by the geotechnical consultant based on field conditions. 3. Pad overexcavation and recompaction should be performed if evaluated to be necessary by the geotechnical consultant. GeoSoilSf inc. SKIN FILL OF NATURAL GROUND DETAIL Plate E-10 Natural grade Proposed pad grade Subgrade at 2 percent gradient, draining toward street Bedrock or approved native material 3- to 7-foot minimum* overexcavate and recompact per text of report Typical benching CUT LOT OR MATERIAL-TYPE TRANSITiON Proposed pad grade Natural grade Bedrock or approved native Typical benching material 3- to 7-foot minimum* overexcavate and recompact per text of report * Deeper overexcavation may be recommended by the geotechnical consultant in steep cut-fill transition areas, such that the underlying topography is no steeper than 31 (H^V) (4-foot minimum) CUT-FILL LOT (DAYLIGHT TRANSITION) G«^$0UMftmc, TRANSITION LOT DETAILS Plate E-12 SIDE VIEW Test pit TOP VIEW Geo,|N»£ts, flic. TEST PIT SAFETY DIAGRAM Plate E-20