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HomeMy WebLinkAboutCDP 06-25; Hagey Residence; Geotechnical Evaluation; 2006-11-20FROMN John S Beer, Architect m£, FAX NO. : 1 760 4382963 ^ 18 2008 08:49^ P2 "—~"\RECORD COPY initial " - " Geotechnical • Coastal ' Geologic • Environmental Palmer Way • Carlsbad, California 9201 0 - (760)438-3155 • FAX (760) 931-0915 November 20,2006 W.O.3213-A1-SC Mr. Ted Hagey P.O. Box 99961 San Diego, California 92169-3961 Subject: Geotechnica! Update and Discussion of the Relative Stability of the Proposed Development at 2497 Ocean Street, Carlsbad, San Diego County, California Dear Mr. Hagey: In accordance with a request by Mr. Jason Goff of the City of Carlsbad, GeoSoils, Inc. (GSI) has prepared this letter for the purpose of updating our previous referenced reports (see Appendix). This update is based on visual observations made during a site reconnaissance performed on November 10, 2006, and GSI's previous reports (see Appendix). Recommendations contained in the previous reports, which are not specifically superceded by this review, should be properly incorporated into the design and construction phases of site development. RESPONSE TO CITY COMMENT In accordance with an email request from the City dated October 19, 2006, GSI has reviewed the referenced GSI reports (see the Appendix) with respect to the anticipated performance of the currently planned project over a 75-year period. Our previous slope stability analysis (GSI, 2003) indicates a factor-of-safety greater than 1.5 (static), and 1.1 (seismic), against failure, for the existing maximum height of the natural slope. The surficial stability of the proposed slopes have also been analyzed. Our evaluation generally indicates a surficiaJ factor-of-safety greater than 1.5 for the existing slope. In addition to the previous stability analysis, the site is located on the perimeter of Buena Vista Lagoon and generally not subjected to marine erosion, but may be subject to sub-areal erosion. Provided that the recommendations contained with the referenced reports are properly implemented, the proposed development is reasonably safe from coastal and geotechnical hazards over its estimated 75-year economic life expectancy, assuming normal care, maintenance, and rainfall. C t oTft FAX NO : 1 760 4382963 ^> 18 2008 08:50ftM P3 FROM': John S Beery flrchitect PIfl FHX NU. ^^ ANP RECOMMENDATIONS Geotechnically, the subject site is in essentially the same condition as it appeared during the preparation of our previous reports (see Appendix). Based upon the review of the current plans (see Appendix), the proposed development of the site is generally consistent with that described in our previous report with the exception of a lower level basement. Tiieiefure, me referenced geotechnical reports are considered relevant and applicable to the proposed construction, except as superceded herein. Basement Wails Exterior basement walls should be waterproofed. If gravel backdrains for the basement walls are proposed, the drains should be installed below the slab. The collector pipe should maintain a minimum slope of 1 percent to an approved outlet pipe. The excavation of any water within the drain system should be performed via gravity flow drainage. If a gravity system is not feasible, then a sump pump system should be considered. In lieu of backdrains. the basement walls should be sealed and designed to withstand the increased hydrostatic pressure. Should this be the case, supplemental recommendations may be provided upon request. The retaining wall backfill and drainage should be constructed in accordance with the recommendations provided in GS1 (2003), and herein. The potential for perched water conditions (GSI, 2003) should be disclosed to all owners as well as all interested/affected parties. Perimeter Conditions It should be noted, that the Uniform Building Code/California Building Code ([UBC/CBC], International Conference of Building Officials [ICBO], 1997 and 2001) indicates that removals of unsuitable soils be performed across all areas to be graded, not just within the influence of the residential structure. Relatively deep removals may also necessitate a special zone of consideration, on perimeter/confining areas. This potential "perimeter" zone would be approximately equal to the depth of removals, if removals cannot be performed offsite. Thus, any settlement sensitive improvements (walls, curbs, flatwork, etc.), constructed within this potential zone may require deepened foundations, reinforcement, etc., or will retain some potential for settlement and associated distress. This will require proper disclosure to all owners as well as all interested/affected parties, if this condition exists at the conclusion of grading. Soil Moisture Considerations It should be noted that the foundation construction recommendations provided in GSI (1993 and 2003) were not intended to preclude the transmission of water or vapor through the slab. 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 Mr.TedHagey W.0.3213-A1-SC 2497 Ocean Street. Carlsbad November 20,2006 File:e:\wp9\32o0\3213a1.gua Page 2 GeoSoils, Inc. (State of California, 2006). Therefore, the following should be considered by the structural engineer/foundation/slab designer to mitigate the transmission of water, or water vapor, through the slab: Con&rete~~5lcib uricierlaymfinT should consist of 2 inchco of Band (G.C. if.30), underlain by a 10- to 15-mil vapor retarder (ASTM E-1745 - Class A or B type), and shall be installed per the recommendations of the manufacturer, including all penetrations (I.e., pipe, ducting, rebar, etc.). The manufacturer shall provide instructions for lap sealing, including minimum width of lap, method of sealing, and efthei supply or specify suitable products tor lap sealing (ASTM E-1745). The vapor retarder should be, in turn, underlain by 4 inches of pea gravel and/or fine to coarse washed clean gravel (80 to 100 percent greater than #4 sieve) to break the capillary rise of soil moisture. Concrete should have a maximum water/cement ratio of 0.50. Slabs should minimally be 5 inches thick. • Additional recommendations regarding water or vapor transmission should be provided by the structural engineer/slab or foundation designer. CTL Thompson (2005) stated "very few slabs emit moisture to the extent that it is identified as a problem. Most residential slabs-on-grade will allow the successful installation of carpet and resilient flooring. However, moisture problems on residential slabs-on-grade are not predictable. The homebuilder (and ultimately the buyer) must choose between the additional cost of installing a vapor retarder.." [system] "..and the potential risk of future moisture problems. Current literature suggests that a capillary break is adequate for slabs that are not to be covered with moisture sensitive flooring. However, to increase performance when a moisture sensitive covering is anticipated, the literature reviewed suggests that a vapor retarder is required." Please be aware that the above should be implemented if the transmission of water or water vapor through the slab is undesirable. Should these recommendations not be implemented, then the potential for water or vapor to pass through the foundations and slabs and resultant distress cannot be precluded and should be disclosed to any owners and all interested/affected parties. Mr.TedHagey W.0.3213-A1*SC 2497 Ocean Street, Carlsbad November 20 2006 a _ _ ...GeoSoils, Inc. (State of California, 2006). Therefore, the following should be considered by the structural engineer/foundation/slab designer to mitigate the transmission of water, or water vapor, through the slab: Concrete-slab una'erlaymem annum consist of 2 inchco of aand (G.C. . _ underlain by a 10- to 15-mil vapor retarder (ASTM E-1745 - Class A or B type), and shall be installed per the recommendations of the manufacturer, including all penetrations (i.e., pipe, ducting, rebar, etc.). The manufacturer shall provide instructions for lap sealing, including minimum width of lap, method of sealing, and eithei supply or specify suirafcle products tor lap sealing (ASTM E-1745). The vapor retarder should be, in turn, underlain by 4 inches of pea gravel and/or fine to coarse washed clean gravel (80 to 100 percent greater than #4 sieve) to break the capillary rise of soil moisture. • Concrete should have a maximum water/cement ratio of 0.50. Slabs should minimally be 5 inches thick. Additional recommendations regarding water or vapor transmission should be provided by the structural engineer/slab or foundation designer. CTL Thompson (2005) stated "very few slabs emit moisture to the extent that it is identified as a problem. Most residential slabs-on-grade will allow the successful installation of carpet and resilient flooring. However, moisture problems on residential slabs-on-grade are not predictable. The homebuilder (and ultimately the buyer) must choose between the additional cost of installing a vapor retarder.." [system] "..and the potential risk of future moisture problems. Current literature suggests that a capillary break is adequate for slabs that are not to be covered with moisture sensitive flooring. However, to increase performance when a moisture sensitive covering is anticipated, the literature reviewed suggests that a vapor retarder is required." Please be aware that the above should be implemented if the transmission of water or water vapor through the slab is undesirable. Should these recommendations not be implemented, then the potential for water or vapor to pass through the foundations and slabs and resultant distress cannot be precluded and should be disclosed to any owners and all interested/affected parties. Mr. Ted Hagey W.0.3213-A1-SC 2497 Ocean Street, Carlsbad November 20,2006 File:e^wp9\32oovi213ai.gua Page 3 GeoSoils, Inc. SUMMARY OF RECOMMENDATIONS REGARDING GEQTECHNICAL OBSERVATION AND TESTING We recommend that observation and/or testing be performed by GSI at each of the following construction stages: • During grading/recertffication. • During excavation. During placement of subdrains, toe drains, or other subdrainage devices, prior to placing fill and/or backfill. After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. Prior to pouring any slabs or flatwork, after presoaking/presaturation of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor barriers (i.e., visqueen, etc.). During retaining wall subdrain installation, prior to backfill placement. During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. • During slope construction/repair. • When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed, prior to construction. • A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and clear documentation of site work, and/or to comply with code requirements. • GSI should review project sales documents to homeowners/homeowners associations for geotechnical aspects, including irrigation practices, the conditions outlined above, etc., prior to any sales. At that stage, GSI will provide homeowners maintenance guidelines which should be incorporated into such documents. Mr. Ted Hagey W.0.3213-A1 -SC 2497 Ocean Street, Carlsbad November 20.2006 Re;e:\wp9\3200\32l3al.gua Page 4 GeoSoils, Inc. JOKn s Beer, *cM tect fl.f- F* NO. = 1 768 4382%3 r. OTHER DESIGN The design civil engineer, structural engineer, post-tension designer, architect, landscape architect, wall designer, etc., should review the rf?comnnendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plans. This report presents minimum design criteria for the design of slabs, foundations, and other elements possibly applicable to the project. These criteria should not be considered as substitutes for actual designs by the structural engineer/designer. Please note that the recommendations contained herein are not intended to preclude the transmission of water or vapor through the slab or foundation. The structural engineer/foundation and/or slab designer should provide recommendations to not allow water or vapor to enter into the structure so as to cause damage to another building component, or so as to limit the installation of the type of flooring materials typically used for the particular application. The structural engineer/designer should analyze actual soil-structure interaction and consider, as needed, bearing, expansive soil influence, and strength, stiffness, and deflections in the various slab, foundation, and other elements in order to develop appropriate design-specific details. As conditions dictate, it is possible that other influences will also have to be considered. The structural engineer/designer should consider all applicable codes and authoritative sources where needed. If analyses by the structural engineer/designer result in less critical details than are provided herein as minimums, the minimums presented herein should be adopted. It is considered likely that more restrictive details will be required. If the structural engineer/designer has any questions or requires further assistance, they should not hesitate to call or otherwise transmit their requests to GSI. In order to mitigate potential distress, the foundation and/or Improvement's designer should confirm to GSI and the governing agency, in writing, that the proposed foundations and/or Improvements can tolerate the amount of differential settlement and/or expansion characteristics and other design criteria specified herein. PLAN REVIEW Rnal project plans (grading, foundation, retaining wall, landscaping, etc.), should be reviewed by this office prior to construction, so that construction is in accordance with the conclusions and recommendations of this report. Based on our review, supplemental recommendations and/or further geotechnical studies may be warranted. W.0.321S-A1-SC2497 Ocean Street, Carlsbad November 20,2006 Fiie:e:\wp9\3aoo\3213a1.gua Page 5 GeoSoifs, lite. FROM : John S flrcKitect fllfi^ FfiX NO. : 1 760 4382963 18 2008 08:51RM P7 The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops or nnndrtinne expoeed during maaa grading. 3ilw conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data the conclusions and recommendations are professional opinions. These opinronG- have been derived in accordance with current standards of Dfactice. anri nr» "«"*"**- eiitier express or implied, is given. Standards of practice are subject to change with time. GS! assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when QSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Thus, this report brings to completion our scope of services for this portion of the project. The opportunity to be of service is sincerely appreciated. If you should have any questions, please do not hesitate to contact our office. Respectfully GeoSoils, Inc. rigineering David W. Skelly Civil Engineer, RCE BV/JPF/DWS/jk Attachment: Appendix - References Distribution: (2) Addressee (1) John Beery A.IA Architect & Associate, Inc., Attention: Mr. Brian Harr (1) City of Carlsbad, Attention: Mr. Jason Goff (e-mail only) Mr. Ted Hagey 2497 Ocean Street, Carlsbad Rle:e:\wp9\3200\3213a1 .gua GeoSoifs, Inc. W.O.3213-A1-SC November 20,2006 Page 6 /-•FROM :-'John S Beery flrchitect flft^ FflX NO. : 1 760 4382963 WHar. 18 2008 08:52flM P8 Arrurvuix Beery Group, Inc., not dated, Hagey residence, Jefferson Street, Carlsbad, California, Job no. 2610. CTL Thompson, 2005, Controlling moisture-related problems associated with basement slabs-on-grade in new residential construction. GeoSoils, Inc., 2003, Update preliminary geotechnical evaluation, APNs 155-140-37 and 155-140-38, City of Carlsbad, San Diego County, California, W.0.3213-A-SC, dated September 18. , 1993, Preliminary geotechnical evaluation, Parcel 155-140-09, Carlsbad, Ca., W.0.1624-A-SC, dated November 2. State of California, 2006, Civil Code, Sections 896-897. GeoSoils, Inc. RECORD COPY ? : -3 - Initial Date GEOTEGHNICAL EVALUATiON APNis 155^140-37 AND l$5-140-38 CITY OF QARLSBAD, SAN blEGO COUNTY, CALIFORNIA MR; EDVVARP H: HAQEY P.O. BOK 99961 SAN DIEGO, CALIFORNIA 92169-3961 W.0.3213-A-SC SEPTEMBER 18, 2003 I Geotechnical • Geologic • Coastal • Environmental 5741 Palmer Way • Carlsbad, California 92010 • (760)438-3155 • FAX (760) 931-0915 September 18,2003 W.O. 3213-A-SC Mr. Edward H. Hagey P.O. Box 99961 San Diego, California 92169-3961 Subject: Updated Preliminary Geotechnical Evaluation, APNs 155-140r37 and 155-140-38, City of Carlsbad, San Diego County, California Dear Mr. Hagey: In accordance with your request, GeoSoils, Inc. (GSI), has reviewed site conditions and the referenced report prepared by GSI (1993), with respect to the proposed development of the subject site. Unless specifically superceded in the text of this report, recommendations contained in that report (see Appendix A) are considered valid and applicable. The following comments and/or additional recommendations are based on our understanding of the proposed development, previous and additional field exploration, a review of site conditions and a review of the referenced documents. EXECUTIVE SUMMARY Based on our review of the available data (see Appendix A), as well as field exploration, laboratory testing, and geologic and engineering analysis, development of the property appears to be feasible from a geotechnical viewpoint, provided the recommendations presented in the text of this report are properly incorporated into design and construction of the project. The most significant elements of this study are summarized below: • All existing undocumented artificial fill, colluvium/topsoil, and near surface weathered terrace deposits are generally loose and potentially compressible, and are not suitable for the support of settlement sensitive improvements. These materials will require removal and recompaction if settlement sensitive improvements are proposed within their influence. In general, removals will be on the order of ±2 to ±8 feet across a majority of the site, however, deeper removals cannot be precluded. Depth of removals are outlined in the conclusions and recommendations section of this report. • Regional groundwater and surface water are not anticipated to significantly affect site development, provided that the recommendations contained in this report are T T 1 I incorporated into final design and construction, and prudent surface and subsurface drainage practices, including proper irrigation, are incorporated into the construction plans. Perched groundwater conditions along fill/bedrock contacts, and along zones of contrasting permeabilities, may not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Our laboratory test results indicate the expansion potential of onsite soils is very low to low, in accordance with Standard No. 18-2 of the Uniform Building Code (UBC, International Conference of Business Officials [ICBO], 1997). It is anticipated that earthwork performed onsite will generally result in very low to low expansive soil conditions. However, onsite soils exhibiting a medium expansive potential may not be precluded. ' The soluble sulfate content of the site soils have been tested to be moderate and site soils are classified as severely corrosive toward ferrous metals. Thus, consultation with a corrosion engineer should be recommended. On a preliminary basis, the use of Type II, concrete is anticipated per Table 19-A-4 of the UBC (ICBO, 1997). Based on the available data, conventional foundations utilizing slabs-on-grade, and/or post-tensioned foundation systems may be used. Based on our review and evaluation, the site is expected to have a relatively low exposure to seismic risks (i.e., liquefaction, surface rupture, etc.). The seisrriicity acceleration values provided herein should be considered during the design of the proposed development. Adverse geologic structures that would preclude site development were not observed. The geotechnical design parameters provided herein should be considered during project planning design and construction by the project structural engineer and/or architects. Mr. Edward H. Hagey W.0.3213-A-SC Fte:e:\wp9\3200\3213a.pge Page Two r GeoSoils, Inc. M 1 The opportunity to be of service is greatly appreciated. If you have any questions concerning this report, or if we may be of further assistance, please do not hesitate to contact the project geologist, Bryan E. Voss, at (760) 438-3155. Respectfully submitted, GepSoils, Inc. John P. Franklin Engineering Geologist, CEG BV/JPF/DWS/jk/jh Distribution: (4) Addressee Reviewed by: >kel Civil Engineer, RCE 1 1 Mr. Edward E. Hagey Rle:e:\wp7\3200\3213a.pge W.O.3213-A-SC Page Three GeoSofls, Inc. I TABLE OF CONTENTS SCOPE OF SERVICES 1 SITE CONDITIONS/PROPOSED DEVELOPMENT 1 FIELD STUDIES 3 REGIONAL GEOLOGY 3 EARTH MATERIALS 4 Undocumented Artificial Fill (Map Symbol - Afu) 4 Colluvium/Topsoil (Not Mapped) 4 Older Alluvium (Map Symbol - Qoa) 4 Terrace Deposits (Map Symbol - Qt) 4 Santiago Formation (Map Symbol - Tsa) 5 GEOLOGIC STRUCTURE 5 FAULTING AND REGIONAL SEISMICITY 5 Regional Faults 5 Seismicity 7 Seismic Shaking Parameters 8 GROUNDWATER 9 LIQUEFACTION EVALUATION 9 SEISMIC HAZARDS 10 OTHER GEOLOGIC HAZARDS 10 LABORATORY TESTING 11 Moisture-Density 11 Laboratory Standard 11 Shear Testing 11 Expansion Potential 12 Sulfate/Corrosion Testing 12 PRELIMINARY EARTHWORK FACTORS 12 SLOPE STABILITY 13 Gross Stability Analysis 13 Surficial Slope Stability 13 1 r GeoSoils, |nc. ] CONCLUSIONS AND RECOMMENDATIONS 13 General 13 General Grading 15 Demolition/Grubbing 15 Treatment of Existing Ground 16 Fill Placement 16 Overexcavation/Transitions 17 PRELIMINARY FOUNDATION RECOMMENDATIONS 17 General 17 Preliminary Foundation Design 17 Bearing Value 17 Lateral Pressure 18 Footing Setbacks 18 Construction 18 Expansion Classification - Very Low to Low (E.I. 0 to 50) 19 Expansion Classification - Medium (E.I. 51 to 90) 20 POST-TENSIONED SLAB SYSTEMS 21 Post-Tensioning Institute Method 22 WALL DESIGN PARAMETERS 23 Conventional Retaining Walls 23 Restrained Walls 23 Cantilevered Walls 24 Retaining Wall Backfill and Drainage 24 Wall/Retaining Wall Footing Transitions 28 TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS 28 Expansive Soils and Slope Creep 28 Top of Slope Walls/Fences 29 DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS 30 DEVELOPMENT CRITERIA 32 Slope Deformation 32 Slope Maintenance and Planting 32 Drainage 33 Erosion Control 33 Landscape Maintenance 33 Gutters and Downspouts 34 Subsurface and Surface Water 34 Site Improvements 34 Tile Flooring 35 Additional Grading 35 Mr. Edward E. Hagey Table of Contents F!le:e:\wp9\3200\3213a.pge Page ii - GeoSoils, Inc. Footing Trench Excavation 35 Trenching 35 Utility Trench Backfill 35 SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING 36 OTHER DESIGN PROFESSIONALS/CONSULTANTS 37 PLAN REVIEW • 37 LIMITATIONS 37 FIGURES: Figure 1 - Site Location Map 2 Figure 2 - California Fault Map 6 Detail 1 24 Detail 2 25 Detail 3 26 ATTACHMENTS: Plate 1 - Geotechnical Map Rear of Text Plate 2 - Cross Section A-A' Rear of Text Plate 3 - Cross Section B-B' Rear of Text Appendix A - References Rear of Text Appendix B - Explorations Rear of Text Appendix C - EQFAULT, EQSEARCH, AND FRISKSP Rear of Text Appendix D - Laboratory Data Rear of Text Appendix E - Slope Stability Analysis Rear of Text Appendix F - General Earthwork and Grading Guidelines Rear of Text i r | Mr. Edward E. Hagey Table of Contents L, Fite:e:\wp9\3200\3213a.pge Pageiii ~, GeoSoffs, Inc. UPDATED GEOTECHNICAL EVALUATION APNs 155-140-37 AND 155-140-38 Cm OF CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA SCOPE OF SERVICES The scope of our services has included the following: 1. Review of the referenced geotechnical report (GSI, 1993), available published geologic literature, and private consultants reports in the region (see Appendix A). 2. Geologic field reconnaissance mapping and the excavation of five hand auger borings to verify subsurface data presented in (GSI, 1993), to obtain samples of representative materials, and delineate soil and geologic parameters that may affect the proposed development (see Appendix B). 3. General area! seismicity (see Appendix C). 4. Laboratory testing of representative soil samples collected during our subsurface exploration program (see Appendix D). 4. General liquefaction evaluation. 5. Slope Stability Analysis (see Appendix E). 5. Appropriate engineering and geologic analysis of data collected and preparation of this report. SITE CONDITIONS/PROPOSED DEVELOPMENT The property is a roughly rectangular shaped lot bounded by Jefferson Street on the east, an adjacent residential property to the south, and a condominium complex to the north. Buena Vista Lagoon is located along the western edge of the property (see Figure 1). The property itself consists of a relatively level pad area adjacent to Jefferson Street and a large natural slope, which descends approximately 50 to 55 feet westward from the pad area to Buena Vista Lagoon. Between the pad elevation of approximately 65 feet Mean Sea Level (MSL) and an elevation of approximately 25 feet MSL, the slope descends at an approximate gradient of 21/z:1 (horizontal: vertical). From an elevation of 25 feet MSL to the lagoon level, the slope flattens to a gradient of approximately 4Vfe:1 (h:v). Several small, 3 to 5 feet wide, hand cut (?) terraces are present in the upper portion of the slope. Existing improvements to the property consist of remnants of an old foundation system (retaining walls and concrete slab) located in the northern portion of the existing pad area. GeoSoils, Inc. M)T.poOnadiC«pyrieN*e«»DeUni«Y»rraMrth,MEe4<»6 SoureDato:USGS Base Map: San Luis Roy Quadrangle, California—San Diego Co., 7.5 Minute Series (Topographic) 1968, by USGS, 1"=2000' 1/2 Scale Miles N Raprodueed with permission granted by Them** Bro». Map*. This map I* «opyrlght»<i by Tnom»« Bro». Map*. H l» unlawfulto oopy or reproduoo all or any part thereof, whether for personal use or resale, without permission. AD rights reserved. w.o. 3213-A-SC SITE LOCATION MAP Figure 1 Vegetation on the property in the vicinity of the pad area consists of some small trees and scattered grasses. Vegetation on the slope consists of primarily grasses. Drainage within the property is predominately by sheet flow directed toward Jefferson Street or down the slope face toward Buena Vista Lagoon. It is our understanding that the existing structures will be demolished. The proposed site development will consist of preparing the pad for construction of a new residential structure. Cut and fill grading techniques would be utilized to create design grades for the proposed single-family residential structure. It is anticipated that the residential development will consist of a one- and/or two-story structure with slab-on-grade and continuous footings, utilizing wood-frame construction. Building loads are assumed to be typical for this type of relatively light construction. The need for import soils is unknown. It is anticipated that sewage disposal will be tied into the regional municipal system. FIELD STUDIES Field work conducted during our evaluation of the site consisted of excavating five hand auger borings within the lot to verify near surface soil and geologic conditions presented in GSI's previous report (GSI, 1993). The borings were logged by a geologist from ourfirm. Representative bulk and in-place samples were taken for appropriate laboratory testing. Logs of the borings and previous explorations are presented in Appendix B. The approximate locations of the five borings and five previous exploratory borings (GSI, 1993), are shown on Plate 1. REGIONAL GEOLOGY The subject property is located within a prominent natural geomorphic province in southwestern California known as the Peninsular Ranges. It is characterized by steep, elongated mountain ranges and valleys that trend northwesterly. The mountain ranges are underlain by basement rocks consisting of pre-Cretaceous metasedimentary rocks, Jurassic metavolcanic rocks, and Cretaceous plutonic rocks of the southern California batholith. In the San Diego 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 into the narrow, steep, coastal plain and continental margin of the basin. These rocks have been uplifted, eroded and deeply incised. During early Pleistocene time, a broad coastal plain was developed from the deposition of marine terrace deposits. During mid to late Pleistocene time, this plain was uplifted, eroded and incised. Alluvial deposits have since filled the lower valleys, and young marine sediments are currently being deposited/eroded within coastal and beach areas. Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18.2003 Rte:e:\wp9\3200\3213a.pge Page 3 GeoSofls, Inc. I I 1 T EARTH MATERIALS Earth materials encountered on the site consist of undocumented artificial fill, colluviumAopsoil, older alluvium, terrace deposits, and Santiago Formation. The estimated limits of earth materials are shown on Plate 1. Undocumented Artificial Fill (Map Symbol - Aftrt Undocumented artificial fill onsite was found to generally consist of a brown, damp to moist, loose, silty sand. Thickness of the soil is approximately ±1 to ±8 feet (behind existing ±8 feet high retaining wall constructed along the northwestern edge of the pad area). Minor fills are also presented along the outside edges of the pad. The existing fill at the subject site is considered potentially compressible in its present state, and considered unsuitable for support of additional fill and/or settlement sensitive improvements. These materials will require removal and recompaction, should settlement sensitive improvements be proposed within their influence. Colluvium/Topsoil (Not Mapped) Surficial colluviumAopsoil onsite was found to generally consist of a brown, dry, loose, silty sand with occasional rounded pebbles. Thickness of the soil is approximately ±1 to ±2 feet. Colluvium/topsoil at the subject site is considered potentially compressible in its present state. Accordingly, these soils are considered unsuitable for support of additional fill and/or settlement sensitive improvements in their existing state and will require removal and recompaction, should settlement sensitive improvements be proposed within their influence. Older Alluvium (Map Symbol - Qoa) Older alluvium was encountered below an approximate elevation of 35 to 40 feet MSL on the descending slope. Where encountered, the older alluvium generally consist of reddish brown, damp to moist, silty sand, and is loose to medium dense with depth. Due to the relatively soft and weathered condition of the upper ±2 feet, these sediments should be removed, moisture conditioned, and recompacted and/or processed in place, should settlement-sensitive improvements be proposed within their influence. At the time of this report, these materials are located beyond the anticipated limits of proposed construction and are not anticipated to affect site development. Terrace Deposits (Map Symbol - Qtt Underlying the colluvium/topsoil, Quaternary-age terrace deposits were encountered to a depth of approximately 16 feet below existing grade in Boring B-1 (GSI, 1993) and in the slope face with hand auger B-1 and B-2 during this current study. As encountered, the terrace deposits generally consist of reddish brown, damp to moist, silty sand, and are Mr. Edward E. HageyW.O.3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Rle:e:\wp9\3200\3213a.pge Page 4 GeoSoils, Inc. medium dense to dense with depth. Due to the relatively soft and weathered condition of the upper ±1 foot, these sediments should be removed, moisture conditioned, and recompacted and/or processed in place, should settlement-sensitive improvements be proposed within their influence. This unit typically has a very low to low expansion potential. Santiago Formation (Map Symbol - Tsa) Bedrock materials underlie the project site at depth, and have been mapped by Tan and Kennedy (1996) as belonging to the Eocene-age Santiago Formation. As encountered, the formational materials generally consist of a highly oxidized, reddish brown to light brown, damp to moist, fine to medium-grained clayey sandstone to silty sandstone, and is medium dense/medium stiff to dense/stiff with depth. This unit typically has a very low to medium expansion potential, depending on the clay content of the matrix materials. * GEOLOGIC STRUCTURE ** Nearly horizontal contacts were observed in our exploratory boring between terrace * deposits and the underlying Santiago Formation. Clayey interbeds within the Santiago w Formation also displayed relatively horizontal contacts within the bounding sandstone units *" (GSI, 1993). Regional mapping by Tan and Kennedy (1996) indicates approximately * horizontal to very gently dipping bedding structures. Based on the available, adverse ^ geologic structures are generally not anticipated to adversely affect the proposed development. 4* FAULTING AND REGIONAL SEISM I CITY „ Regional Faults m Our review indicates that there are no known active faults crossing this site within the area „ proposed for development, and the site is not within an Earthquake Fault Zone (Hart and Bryant, 1997). However, the site is situated in an area of active, as well as *" potentially-active, faulting. These include, but are not limited to: the San Andreas fault; the ,„ San Jacinto fault; the Elsinore fault; the Coronado Bank fault zone; and the Newport-lnglewood - Rose Canyon fault zone. The location of these, and other major faults *" relative to the site, are indicated on Rgure 2 (California Fault Map). The possibility of ground acceleration or shaking at the site may be considered as approximately similar to the southern California region as a whole. Major active fault zones that may have a 7 significant affect on the site, should they experience activity, are listed in the following table 1 (modified from Blake, 2000a): Ti Mr. Edward E. Hagey W.0.3213-A-SC | APNs 155-140-37 and 155-140-38 September 18,2003 i. Rte:e:\wp9V3200\3213a.pge Page 5 t GeoSoils, inc. Mi 1100 1000 -- 900-- 800 -- CALIFORNIA FAULT MAP Hagey Residence -400 -300 -200 -100 0 W.O. 3213-A-SC 100 200 300 400 500 600 Figure 2 Y.]," *".M. tl^.*, "^f ~r^i.f ^P."" "iL.*j .. .T^^*" ™ *t% Newport-lnglewood (Offshore) Rose Canyon Coronado Banks Elsinore-Temecula Elsinore-Julian Elsinore-Glen Ivy Palos Verdes Earthquake Valley Newport - Inglwood (LA. Basin) San Jacinto - Anza San Jadnto - San Jacinto Valley Chino - Central Ave. (Elsinore) WhitUer 5.1 (8.2) 5.5 (8.8) 21.4(34.4) 23.8 (38.3) 24.2 (38.9) 32.7 (52.6) 35.0 (56.4) 44.4(71.5) 44.9 (72.3) 46.3 (74.5) 46.7 (75.1) 46.7 (75.1)) 50.1 (80.7) «• I 1 I 1 I 1 Seismicitv The acceleration-attenuation relations of Idriss (1994), and Campbell (1997), Horizontal-Random have been incorporated into EQFAULT (Blake, 2000a). For this study, peak horizontal ground accelerations anticipated at the site were determined based on the random mean plus 1 sigma attenuation curve and mean attenuation curve developed by Joyner and Boore (1982a and 1982b), Sadigh et al. (1987), and Bozorgnia et al. (1999). EQFAULT is a computer program by Thomas F. Blake (2000a), which performs deterministic seismic hazard analyses using up to 150 digitized California faults as earthquake sources. The program estimates the closest distance between each fault and a given site. If a fault is found to be within a user-selected radius, the program estimates peak horizontal ground acceleration that may occur at the site from an upper bound ("maximum credible") earthquake on that fault. Site acceleration (g) is computed by any of at least 30 user-selected acceleration-attenuation relations that are contained in EQFAULT. Based on the EQFAULT program, peak horizontal ground accelerations from an upper bound event at the site may be on the order of 0.38g to 0.65g. The computer printouts of portions of the EQFAULT program are included within Appendix C. Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 Rle:e:\wp9\3200\3213a.pge GeoSoils, Inc. W.O. 3213-A-SC September 18,2003 Page 7 Historical site seismlcity was evaluated with the acceleration-attenuation relations of Campbell (1997) and the computer program EQSEARCH (Blake, 2000b). This program was utilized to perform a search of historical earthquake records for magnitude 5.0 to 9.0 seismic events within a 100-mile radius, between the years 1800 to 2001. Based on the selected acceleration-attenuation relation, a peak horizontal ground acceleration has been estimated, which may have affected the site during the specific seismic events in the past. Based on the available data and attenuation relationship used, the estimated maximum (peak) site acceleration during the period 1800 to 2002 was 0.46g. In addition, a seismic recurrence curve is also estimated/generated from the historical data (see Appendix C). A probabilistic seismic hazards analyses was performed using FRISKSP (Blake, 2000c), which models earthquake sources as 3-D planes and evaluates the site specific probabilities of exceedance for given peak acceleration levels or pseudo-relative velocity levels. Based on a review of these data, and considering the relative seismic activity of the southern California region, a peak horizontal ground acceleration of p.SOg was calculated. This value was chosen as it corresponds to a 10 percent probability of exceedance in 50 years (or a 475-year return period). Computer printouts of the FRISKSP program are included in Appendix C. Seismic Shaking Parameters Based on the site conditions, Chapter 16 of the Uniform Building Code (UBC, International Conference of Building Officials [ICBO], 1997) seismic parameters are provided in the following table: fillliltlM^ Seismic Zone (per Figure 16-2*) Seismic Zone Factor (per Table 16-1*) Soil Profile Type (per Table 1 6-J*) Seismic Coefficient C, (per Table 16rQ*) Seismic Coefficient Cv (per Table 16-R*) Near Source Factor Na (per Table 16-S*) Near Source Factor H, (per Table 16-T*) Distance to Seismic Source Seismic Source Type (per Table 16-U*) Upper Bound Earthquake (Rose Canyon fault) (-•utit-tUh^'i ,rr'irX'~T,iiH.in.i'iTr'i!'.._ '^ * '-''"i"! 'i !.':3t.:lsEisMidL PARAMETERS?, ^ 4 0.40 So 0.44N, 0.64^ 1.0 1.05 5.1 mi (8.2 km) B MW6.9 *Figure and Table references from Chapter 1 6 of the UBC (ICBO, 1997) Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 Rle:e:\wpS\3200\3213a.pge W.0.3213-A-SC September 18,2003 PageB GeoSoils, Inc. GROUNDWATER Groundwater was not encountered within the property during field work performed in preparation of this report. Subsurface regional water is not anticipated to adversely affect site development, provided that the recommendations contained in this report are incorporated into final design and construction. Prudent surface and subsurface drainage practices should be incorporated into the construction plans. 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. Seeps, springs, or other indications of a high groundwater level were not detected on the subject property during the time of our field investigation. However, seepage may occur locally (due to heavy precipitation or Irrigation) in areas where fill soils overlie silty or clayey soils. Such soils may be encountered in the earth units that exist onsite. Perched groundwater conditions along fill/bedrock contacts and along zones of contrasting permeabilities should not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. LIQUEFACTION EVALUATION 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 lateral movement sliding, consolidation and settlement of loose sediments, sand boils, and other damaging deformations. This phenomenon occurs only below the water table, but after liquefaction has developed, it can propagate upward into over-lying, non-saturated soil, as excess pore water dissipates. Liquefaction susceptibility is related to numerous factors and the following conditions must exist for liquefaction to occur: 1) sediments must be relatively young in age and not have developed large amounts of cementation; 2) sediments must consist mainly 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 seismic event of a sufficient duration and large enough magnitude to induce straining of soil particles. It should be noted that throughout our site observations and subsurface investigation, there was no evidence of upward-directed hydraulic force that was suddenly applied, and was of short duration, nor were there any features commonly caused by seismically induced Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Rte:e:\wp9\3200\3213a.pge Page 9 -; G«oSoi Is, Inc. liquefaction, such as dikes, sills, vented sediment, lateral spreads, or soft-sediment deformation. These features would be expected if the site area had been subject to liquefaction in the past (Obermeier, 1996). Inasmuch as the future performance of the site with respect to liquefaction should be similar to the past, excluding the effects of urbanization (irrigation), GSI concludes that the site generally has not been subject to liquefaction in the geologic past, regardless of the depth of the localized water table. Since at least one or two of the five required concurrent conditions discussed above do not have the potential to affect the site where it is proposed to be developed at this time, and evidence of paleoliquefaction features were not observed, our evaluation indicates that the potential for liquefaction and associated adverse effects within the areas of the site proposed development is low, even with a future rise in groundwater levels. The site conditions will also be improved by removal and recompaction of low density near-surface soils. SEISMIC HAZARDS The following list includes other seismic related hazards that have been considered during our evaluation of the site. The hazards listed are considered negligible and/or completely mitigated as a result of site location, soil characteristics, and typical site development procedures: • Dynamic Settlement • Surface Fault Rupture • Ground Lurching or Shallow Ground Rupture It is important to keep in perspective that in the event of a "maximum probable" or "maximum credible" (upper bound) earthquake occurring on any of the nearby majorfaults, strong ground shaking would occur in the subject site's general area. Potential damage to any structure(s) would likely be greatest from the vibrations and impelling force caused by the inertia of a structure's mass than from those induced by the hazards considered above. This potential would be no greater than that for other existing structures and improvements in the immediate vicinity. OTHER GEOLOGIC HAZARDS 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, surfidal 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 1969,1978,1980,1983,1993, and 1998, creep-affected materials may become saturated, resulting in a more rapid form of downslope movement (i.e., landslides and/or surficial failures). Examples of these types of slope instability do not exist within the site. Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Rle:e:\wp9\3200\3213a.pge Page 10 GeoSoils, Inc. LABORATORY TESTING Laboratory tests were performed on representative samples of the onsite earth materials in order to evaluate their physical characteristics. The test procedures used and results obtained are presented below. Moisture-Density The field moisture content and dry unit weight were determined for each undisturbed sample of the soils encountered in the borings. The dry unit weight was determined in pounds per cubic foot (pcf), and the field moisture content was determined as a percentage of the dry weight. The results of these tests are shown on the Boring Logs (see Appendix B). Laboratory Standard The maximum dry density and optimum moisture content was determined for the major soil type encountered in the borings. The laboratory standard used was ASTM D-1557. The moisture-density relationship obtained for this soil is shown below: Silty Sand, Orange Brown 0'-3'119.0 13.5 -r Shear Testing Shear testing was performed on a representative, undisturbed sample of site soil in general accordance with ASTM Test Method D-3080, in a Direct Shear Machine of the strain control type. Shear test results are presented as Plate D-1 in Appendix D, and as follows: 1 1 Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 File:e:\wp0\3200\3213a.pge GeoSoils, Inc. W.0.3213-A-SC September 18, 2003 Page 11 Expansion Potential Expansion testing was performed on a representative sample of site soil in accordance with UBC Standard 18-2. The results of expansion testing are presented in the following table: Sulfate/Corrosion Testing A typical sample of the site material was analyzed for corrosion/acidity potential. The testing included determination of soluble sulfates, pH, and saturated resistivity. Results indicate that site soils are slightly acidic (pH=6.5) with respect to acidity and are severely corrosive to ferrous metals. Severely corrosive soils are considered to be below 1,000 ohms-cm. Based upon the soluble sulfate results of 0.144 percent by weight in soil, the site soils have a severe corrosion potential to concrete (UBC range for severe sulfate exposure is 0.10 to 0.20 percentage by weight soluble [SO4] in soil. On a preliminary basis, the use of Type II concrete is anticipated according to Table 19-A-4 of the UBC (ICBO, 1997). Alternative methods and additional comments may be obtained from a qualified corrosion engineer. PRELIMINARY EARTHWORK FACTORS Preliminary earthwork factors (shrinkage and bulking) for the subject property have been estimated based upon our field and laboratory testing, visual site observations, and experience with similar projects. It is apparent that shrinking would vary with depth and with areal extent over the site based on previous site use. Variables include vegetation, weed control, discing, and previous filling or exploring. However, all these factors are difficult to define in a three-dimensional fashion. Therefore, the information presented below represents average shrinkage/bulking values: Undocumented Artificial Rll 10-20% shrinkage Colluvium/Topsoil 10-20% shrinkage Quaternary Terrace Deposits 10-15% shrinkage Tertiary Santiago Formation 0-6% shrinkage An additional shrinkage factor item would include the removal of root systems of individual large plants or trees. These plants and trees vary in size, but when pulled, they may generally result in a loss of Vz to 1 Vz cubic yards. This factor needs to be multiplied by the Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 File:e:\wp9\3200\3213a.pge W.O.3213-A-SC September 18. 2003 Page 12 GeoSoils, Inc. number of significant plants, trees, or tree roots present to determine the net loss. The above facts indicate that earthwork balance for the site would be difficult to define and flexibility in design is essential to achieve a balanced end product. SLOPE STABILITY Conventional slope stability analyses were performed utilizing the PC version of the computer program GSTABL7 v.2. The program performs a two-dimensional limit equilibrium analysis to compute the factor of safety for a layered slope using the simplified Bishop or Janbu methods. Representative geologic cross sections were prepared for analysis, utilizing field and laboratory data from our referenced report and this report and the 25-scale design study, depicting maximum existing slopes, as indicated on Cross Sections B-B' (see Plate 3). The results of the analyses are included in Appendix E. Gross Stability Analysis A calculated factor-of-safety greater than 1.5 or 1.1 has been obtained for the existing, maximum height of the natural slope, when analyzed from a static or seismic viewpoint, respectively. The results of the analyses are included in Appendix E. Surflcial Slope Stability The surficial stability of the proposed slopes have been analyzed. Our evaluation generally indicates a surficial safety factor greater than 1.5 for the existing slope. CONCLUSIONS AND RECOMMENDATIONS General Based on our field exploration to date, laboratory testing, and geotechnical engineering evaluations, it is our opinion that the site appears feasible for the proposed development from a geotechnical engineering and geologic viewpoint, provided that the recommendations presented in the following sections are incorporated into the design and construction phases of site development. The primary geotechnical concerns with respect to the proposed development are: • Depth to competent bearing strata. • Expansion and corrosion potential of site soils. • Potential for perched groundwater. • Slope stability. • Regional seismic activity. Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18. 2003 Rte:e:\wp9\3200\3213a.pge Page 13 GeoSofls, Inc. The recommendations presented herein consider these, as well as other aspects of the site. The engineering analyses performed concerning site preparation and the recommendations presented herein, have been completed using the information provided and obtained during our field work. In the event that any significant changes are made to proposed site development, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed, and the recommendations of this report verified or modified in writing by this office. Foundation design parameters are considered preliminary until the foundation design, layout, and structural loads are provided to this office for review. 1. Soil engineering, observation, and testing services should be provided during grading to aid the contractor in removing unsuitable soils and in his effort to compact the fill. 2. Geologic observations should be performed during grading to verify and/or further evaluate geologic conditions. Although unlikely, if adverse geologic structures are encountered, supplemental recommendations and earthwork may be warranted. 3. The undocumented artificial fill and weathered near-surface terrace deposits, are typically porous, loose, and subject to settlement. In the near surface, they are considered potentially compressible in their existing state, and have a very low to moderate potential for hydrocollapse; thus, undocumented artificial fill and weathered near-surface terrace deposits may settle appreciably under additional fill, foundation, or improvement loadings and will require removal and recompaction (and/or processing in-place) if settlement-sensitive improvements are proposed within their influence. In general, removals will be on the order of ±2 to ±3 feet across the majority of the site. Removals will be on the order of ±2 to ±8 feet behind the existing ±8-foot high retaining wall, constructed along the northwest edge of the pad area; however, locally deeper removals may be necessary. 4. GSI performed a liquefaction screening evaluation of existing conditions using the available data. It is our opinion that the area site proposed for development at this time, is generally underlain by dense/stiff formational sediments, which have a very low potential for liquefaction. 5. Groundwater is generally not anticipated to affect site development, providing that the recommendations contained in this report are incorporated into final design and construction, and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities should not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37. and 155-140-38 September 18,2003 Rle:e:\wp9\3200\3213a,pge Page 14 GeoSoils, Inc. 6. Our laboratory test results and experience on nearby sites related to expansion potential, indicate that soils with very low to low to potentially medium expansion indices underlie the site. This should be considered during project design. Foundation design and construction recommendations are provided herein for medium and high expansion potential classifications. 7. The soluble sulfate content of the site soils have been tested to be moderate and site soils are classified as severely corrosive toward ferrous metals. Thus, consultation with a corrosion engineer should be considered. On a preliminary basis, the use of Type II concrete is anticipated according to Table 19-A-4 of the UBC (ICBO, 1997). 8. The seismicity-acceleration values provided herein should be considered during the design of the proposed development. 8. General Earthwork and Grading Guidelines are provided at the end of this report as Appendix F. Specific recommendations are provided below. General Grading All grading should conform to the guidelines presented in the UBC (ICBO, 1997), the City and/or County, and Appendix F (this report), except where specifically superceded in the text of this report. When code references are not equivalent, the more stringent code should be followed. 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 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. Demolition/Grubbing 1. Existing structures, vegetation, and any miscellaneous debris should be removed from the areas of proposed grading. 2. Any previous foundations, irrigation lines, cesspools, septic tanks, leach fields, or other subsurface structures uncovered during the recommended removal should be observed by GSI so that appropriate remedial recommendations can be provided. 3. Cavities or loose soils remaining after demolition and site clearance should be cleaned out and observed by the soil engineer. The cavities should be replaced with fill materials that have been moisture conditioned to at least optimum moisture content and compacted to at least 90 percent of the laboratory standard. Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18. 2003 Re:e:\wp9\3200\3213a.pge Page 15 GeoSoils, Inc. Treatment of Existing Ground 1. All undocumented artificial fill and weathered near-surface terrace deposits should be removed to suitable terrace deposits and/or bedrock (i.e. Santiago Formation), cleaned of deleterious materials, as necessary, moisturized, and recompacted if not removed by proposed excavation within areas proposed for settlement-sensitive improvements. Variations from these thicknesses should be anticipated. At this time, removal depths on the order of ±2 to ±3 feet across the majority of the site. Removals will be on the order of ±2 to ±8 feet behind the existing ±8-foot high retaining wall constructed along the northwest edge of the pad area should be anticipated; however, locally deeper removals may be necessary. 2. Subsequent to the above removals, the upper 12 inches of the exposed subsoils/bedrock should be scarified, brought to at least optimum moisture content, and recompacted to a minimum relative compaction of 90 percent of the laboratory standard. 3. Existing artificial fill, etc., and removed natural ground materials may be reused as compacted fill provided that major concentrations of vegetation and miscellaneous debris are removed prior to, or during, fill placement. 4. Localized deeper removal may be necessary due to buried utility trenches or dry porous materials. The project soils engineer/geologist should observe all removal areas during the grading. Fill Placement 1. Subsequent to ground preparation, fill materials should be brought to at least optimum moisture content, placed in thin 6- to 8-inch lifts, and mechanically compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard. 2. Fill materials should be cleansed of major vegetation and debris prior to placement. 3. Any import materials should be observed and determined suitable by the soils engineer prior to placement on the site. Import material, if any, for a fill cap should be low expansive (E.I. less than 50). Foundation designs may be altered if import materials have a greater expansion value than the onsite materials encountered in this investigation. 4. Any oversized rock materials greater than 8 inches in diameter should be placed under the recommendations and supervision of the soils engineer and/or removed from the site. Per the UBC, such materials may not be placed within 10 feet of finish grade. General recommendations for placement of oversize materials is contained in Appendix F (General Earthwork and Grading Guidelines). Although unlikely, Mr. Edward E. Hagey :W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18.2003 File:e:\wp9\3200\3213a.pge Page 16 GeoSoils, Inc. should significant amounts of oversize rock be encountered, recommendations for rock fill placement should be adhered to. Overexcavation/Transitions In order to provide for the uniform support of the structures, a minimum 3-foot thick fill blanket is recommended for lots containing earth material transitions. Any cut portion of the pad for the development should be overexcavated a minimum 3 feet below finish pad grade, to 5 feet horizontally, or a 1:1 (h:v) projection, down and away from settlement sensitive improvements. Areas with planned fills less than 3 feet should be overexcavated in order to provide the minimum fill thickness. Maximum to minimum fill thickness within a given lot or pad should not exceed a ratio of 3:1 (max:min). PRELIMINARY FOUNDATION RECOMMENDATIONS General In the event that the information concerning the proposed development plan is not correct, or any changes in the design, location, or loading conditions of the proposed structure 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. It is our understanding that slab-on-grade construction is desired for the proposed development. The information and recommendations presented in this section are not meant to supercede design by the project structural engineer. Upon request, GSI could provide additional input/consultation regarding soil parameters, as related to foundation design. Preliminary Foundation Design Our review, field work, and laboratory testing indicates that onsite soils have a very low to low to possible medium expansion potential. Preliminary recommendations for foundation design and construction are presented below. Final foundation recommendations should be provided at the conclusion of grading, and based on laboratory testing of fill materials exposed at finish grade. Bearing Value 1. The foundation systems should be designed and constructed in accordance with guidelines presented in the latest edition of the UBC. 2. An allowable bearing value of 1,500 pounds per square foot (psf) may be used for the design of continuous footings at least 12 inches wide and 12 inches deep, and column footings at least 24 inches square and 24 inches deep. This value may be Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18, 2003 Rle:e:\wp9\3200VJ213a.pge Page 17 GeoSoils, Inc. I 1 7 increased by 20 percent for each additional 12 inches in depth to a maximum of 2,500 psf. No increase in bearing value is recommended for increased footing width. Lateral Pressure 1. For lateral sliding resistance, a 0.35 coefficient of friction may be utilized for a concrete to soil contact when multiplied by the dead load. 2. Passive earth pressure may be computed as an equivalent fluid having a density of 250 pounds per cubic foot (pcf) with a maximum earth pressure of 2,500 psf. 3. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. Footing Setbacks All footings should maintain a minimum 7-foot horizontal setback from the base of the footing to any descending slope. This distance is measured from the footing face at the bearing elevation. Footings should maintain a minimum horizontal setback of H/3 (H = slope height) from the base of the footing to the descending slope face and no less than 7 feet, nor need to be greater than 40 feet. Footings adjacent to unlined drainage swales should be deepened to a minimum of 6 inches below the invert of the adjacent unlined swale. Footings for structures adjacent to retaining walls should be deepened so as to extend below a 1:1 projection from the heel of the wall. Alternatively, walls may be designed to accommodate structural loads from buildings or appurtenances as described in the retaining wall section of this report. Construction The following foundation construction recommendations are presented as a minimum criteria from a soils engineering viewpoint. The onsite soils expansion potentials are generally in the very low to low range (E.I. 0 to 50). Expansive soil in the medium range (E.I. 51 to 90) may also be present onsite. Accordingly, the following foundation construction recommendations assume that the soils in the top 3 feet from finish grade will have a very low to possible medium expansion potential. Recommendations by the projects design-structural engineer or architect, which may exceed the soils engineer's recommendations, should take precedence over the following minimum requirements. Final foundation design will be provided based on the expansion potential of the near surface soils encountered during grading. Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Fite:e:\wp9\3200V3213a.pge Page 18 GeoSof Is, Inc. Expansion Classification - Very Low to Low (ELI.0 to 50) 1. Conventional continuous footings should be founded at a minimum depth of 12 inches below the lowest adjacent ground surface for one-story floor loads and 18 inches below the lowest adjacent ground surface for two-story floor loads. Interior footings may be founded at a depth of 12 inches below the lowest adjacent ground surface. Footings for one-story floor loads should have a minimum width of 12 inches, and footings for two-story floor loads should have a minimum width of 15 inches. All footings should have one No. 4 reinforcing bar placed at the top and one No. 4 reinforcing bar placed at the bottom of the footing. Isolated interior or exterior piers and columns should be founded at a minimum depth of 24 inches below the lowest adjacent ground surface. 2. A grade beam, reinforced as above and at least 12 inches square, should be provided across the garage entrances. The base of the reinforced grade beam should be at the same elevation as the adjoining footings. 3. Concrete slabs in residential and garage areas should be underlain with a vapor barrier consisting of a minimum of 10-mil, polyvinyl-chloride membrane with all laps sealed. This membrane should be covered with 2 inches of sand to aid in uniform curing of the concrete and mitigate puncturing of the vapor barrier. 4. Concrete slabs, including garage slabs, should be a minimum of 4 inches thick, and minimally reinforced with No. 3 reinforcement bars placed on 18-inch centers, in two horizontally perpendicular directions (i.e., long axis and short axis). All slab reinforcement should be supported to ensure proper mid-slab height positioning during placement of the concrete. "Hooking" of reinforcement is not an acceptable method of positioning. 5. Garage slabs should be poured separately from the residence footings and be quartered with expansion joints or saw cuts. A positive separation from the footings should be maintained with expansion joint material to permit relative movement. 6. The residential and garage slabs should have an actual, minimum thickness of 4 inches, and the slab subgrade should be free of loose and uncompacted material prior to placing concrete. 7. Presaturation is not necessary for these soil conditions; however, the moisture content of the subgrade soils should be equal to or greater than optimum moisture to a depth of 12 inches below the adjacent ground grade in the slab areas, and verified by this office within 72 hours of the vapor barrier placement. Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Re:e:\wp9\3200\3213a4>ge Page 19 GeoSoils, Inc. 8. As an alternative, an engineered post-tension foundation system may be used. 9. Soils generated from footing excavations to be used onsite should be compacted to a minimum relative compaction 90 percent of the laboratory standard, whether it is 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. 10. Foundations near the top of slope should be deepened to conform to the latest edition of the UBC (ICBO, 1997) and provide a minimum of 7 feet horizontal distance from the slope face. Rigid block wall designs located along the top of slope should be reviewed by a soils engineer. Expansion Classification -Medium (E.I. 51 to 90) 1. Conventional continuous footings should be founded at a minimum depth of 18 inches belowthe lowest adjacent ground surface for one- or two-story floor loads. Interior footings may be founded at a depth of 12 inches below the lowest adjacent ground surface. Footings for one-story floor loads should have a minimum width of 12 inches, and footings for two-story floor loads should have a minimum width of 15 inches. All footings should be reinforced with a minimum of two No. 4 reinforcing bars at the top and two No. 4 reinforcing bars at the bottom. Isolated interior and/or exterior piers and columns are not recommended. 2. A grade beam, reinforced as above and at least 12 inches square, should be provided across the garage entrances. The base of the reinforced grade beam should be at the same elevation as the adjoining footings. 3. Concrete slabs in residential and garage areas should be underlain by a vapor barrier consisting of a minimum of 10-mil, polyvinyl-chloride membrane with all laps sealed. Two inches of the sand base should be placed over and under the membrane (total of 4 inches) to aid in uniform curing of the concrete and mitigate puncturing of the vapor barrier. 4. Concrete slabs, including garage areas, should be a minimum of 4 inches thick, and minimally reinforced with No. 3 reinforcement bars placed on 18-inch centers, in two horizontally perpendicular directions (i.e., long axis and short axis). All slab reinforcement should be supported to ensure proper mid-slab height positioning during placement of the concrete. "Hooking" of reinforcement is not an acceptable method of positioning. 1 Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Fite:e:\vvp9\3200\3213a.pge Page 20 -, GeoSoils, Inc. 5. Garage slabs should be poured separately from the residence footings and be quartered with expansion joints or saw cuts. A positive separation from the footings should be maintained with expansion joint material to permit relative movement. 6. The residential and garage slabs should have an actual minimum thickness of 4 inches, and the slab subgrade should be free of loose and uncompacted material prior to placing concrete. 7. Presaturation of slab areas is recommended for these soil conditions. The moisture content of each slab area should be 120 percent, or greater, above optimum and verified by the soil engineer to a depth of 18 inches below adjacent ground grade in the slab areas, within 72 hours of the vapor barrier placement. 8. As an alternative, an engineered post-tension foundation system may be used. 9. Soils generated from footing excavations to be used onsite should be compacted to a minimum relative compaction 90 percent of the laboratory standard, whether it is 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. 10. Foundations near the top of slope should be deepened to conform to the latest edition of the UBC (ICBO, 1997) and provide a minimum of 7 feet horizontal distance from the slope face. Rigid block wall designs located along the top of slope should be reviewed by a soils engineer. POST-TENSIONED SLAB SYSTEMS Recommendations for utilizing post-tensioned slabs on the site is based on our limited subsurface investigation on the site. The recommendations presented below should be followed in addition to those contained in the previous sections, as appropriate. The information and recommendations presented below in this section are not meant to supercede design by a registered structural engineer or civil engineer familiar with post-tensioned slab design. Post-tensioned slabs should be designed using sound engineering practice and be in accordance with local and/or national code requirements. Upon request, GSI can provide additional data/consultation regarding soil parameters as related to post-tensioned slab design. From a soil expansion/shrinkage standpoint, a common contributing factor to distress of structures using post-tensioned slabs is fluctuation of moisture in soils underlying the perimeter of the slab, compared to the center, causing a "dishing" or "arching" of the slabs. To mitigate this possibility, a combination of soil presaturation and construction of a perimeter cut-off wall should be employed. Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18.2003 File:e:\wp9\3200\3213a.pge Page 21 GeoSoils, Inc. Perimeter cut-off walls should be a 18 inches deep for medium and/or high expansive soils. The cut-off walls may be integrated into the slab design or independent of the slab and should be a minimum of 6 inches thick. The vapor barrier should be covered with a 2-inch layer of sand to aid in uniform curing of the concrete; and it should be lapped adequately to provide a continuous water-proof barrier under the entire slab. For medium or highly expansive soils, an additional 2 inches of sand should be placed on grade (4 inches total) Specific soil presaturation is not required; however, the moisture content of the subgrade soils should be equal to, or greater than, the soils' optimum moisture content to a depth of 18 inches below grade, for medium, or high expansive soils. Post-Tensionlna Institute Method Post-tensioned slabs should have sufficient stiffness to resist excessive bending due to non-uniform swell and shrinkage of subgrade soils. The differential movement can occur at the comer, edge, or center of slab. The potential for differential uplift can be evaluated using the UBC Section 1816 (ICBO, 1997), based on design specifications of the Post-Tensioning Institute (PTI). The following table presents suggested minimum coefficients to be used in the PTI design method. Thomthwalte Moisture Index Correction Factor for Irrigation Depth to Constant Soil Suction Constant soil Suction (pf) Modulus of Subgrade Reaction (pci) Moisture Velocity -20 inches/year 20 inches/year 7 feet 3.6 75 0.7 inches/month The coefficients are considered minimums and may not be adequate to represent worst case conditions such as adverse drainage and/or improper landscaping and maintenance. The above parameters are applicable provided structures have positive drainage that is maintained away from structures. Therefore, it is important that information regarding drainage, site maintenance, settlements, and effects of expansive soils be passed on to future owners. Based on the above parameters, the following values were obtained from figures or tables of the UBC Section 1816 (ICBO, 1997). The values may not be appropriate to account for possible differential settlement of the slab due to other factors. If a stiffer slab is desired, higher values of ym may be warranted. Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 Rle:e:\wp9\3200\3213a.pge GeoSoils, Inc. W.O. 3213-A-SC September 18,2003 Page 22 em center lift 5.0 feet 5.0 feet 5.5 feet em edge lift 2.5 feet 3.5 feet 4.0 feet ym center lift 1.0 inch 1.7 inches 2.7 inches ym edge lift 0.3 inches plus 0.75 inches 0.75 inches Deepened footings/edges around the slab perimeter must be used to minimize non-uniform surface moisture migration (from an outside source) beneath the slab. An edge depth of 12 inches should be considered a minimum. The bottom of the deepened footing/edge should be designed to resist tension, using cable or reinforcement per the structural engineer. Other applicable recommendations presented under conventional foundation and the California Foundation Slab Method should be adhered to during the design and construction phase of the project. WALL DESIGN PARAMETERS Conventional Retaining Walls The design parameters provided below assume that either very low expansive soils (Class 2 permeable filter material or Class 3 aggregate base) or native materials are used to backfill any retaining walls. The type of backfill (i.e., select or native), should be specified by the wall designer, and clearly shown on the plans. Building walls, below grade, should be water-proofed or damp-proofed, depending on the degree of moisture protection desired. The foundation system for the proposed retaining walls should be designed in accordance with the recommendations presented in this and preceding sections of this report, as appropriate. Footings should be embedded a minimum of 18 inches below adjacent grade (excluding landscape layer, 6 inches) and should be 24 inches in width. There should be no increase in bearing for footing width. Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site specific conditions. Restrained Walls Any retaining wails that will be restrained prior to placing and compacting backfill material or that have re-entrant or male comers, should be designed for an at-rest equivalent fluid pressure (EFP) of 65 pounds per cubic foot (pcf), plus any applicable surcharge loading. For areas of male or re-entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall (2H) laterally from the corner. Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 Rle:e:\wp9\3200\3213a.pge W.O. 3213-A-SC September 18,2003 Page 23 GeoSoils, Inc. 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 superseded by City and/or County standard design. Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. These do not include other superimposed loading conditions due to traffic, structures, seismic events or adverse geologic conditions. When wall configurations are finalized, the appropriate loading conditions for superimposed loads can be provided upon request. Level* 2to1 38 55 45 60 * Level backfill behind a retaining wall is defined as compacted earth materials, property drained, without a slope for a distance of 2H behind the wall, where H is the height of the wall. Retaining Wall Backfill and Drainage Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabric and outlets. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Backdrains should consist of a 4-inch diameter perforated PVC or ABS pipe encased in either Class 2 permeable filter material or Vz-inch to %-inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent). For low expansive backfill, the filter material should extend a minimum of 1 horizontal foot behind the base of the walls and upward at least 1 foot. For native backfill that has up to medium expansion potential, continuous Class 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, and it should be constructed in accordance with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited access and confined areas, (panel) drainage behind the wail may be constructed in accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an expansion index (E.I.) potential of greater than 90 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should conform with Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 Rle:e:\wp9\3200V3213a.pge W.0.3213-A-SC September 18,2003 Page 24 GeoSoiIs, Inc. DETAIL N . T , S . Provide surface drainage ±12'—I Water proofing membrane (optional) (§) Weephole Finished surface (3) Filter fabric A 3/4 or flatter (T) WATER PRDDFING MEMBRANE (optional)" Liquid boot or approved equivalent. © RQCK» 3/4 to i-1/2' (Inches) rock. (3) FILTER FABRIC" , , Mlra-fl 140N or approved "equivalent place fabric flap behind core. © PIPE" 4* (Inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of IX gradient to proper outlet point, (5) WEEPHDLD Minimum 2' (Inches) diameter placed at 20' (feet> on centers along the wall, and 3' (Inches) above finished surface. TYPICAL RETAINING WALL BACKFILL AND DRAINAGE DETAIL DETAIL 1 Geotechnlcal • Geologic • Environmental DETAIL N . T . S , Provide surface drainage T) Water proofing wenbrane (optional)) Native Backfill Slope or Level Native Backfill Z?) Drain (5) Veephole Finished surface or flater (T) WATER PRDDFING MEMBRANE (optlonal)i Liquid boot or approved equivalent. (D DRAINi Mlradraln 6000 or J-draln 200 or equivalent for non-waterproofed walls. Mlradraln 6200 or J-idraln 200 or equivalent for water proofed walls. @ FILTER FABRIC" . Mlrafl 140N or. approved equivalent place fabric flap behind core. (4) PIPE 4' (Inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of IX gradient to proper outlet point. WEEPHQLEiMinimum S' (Inches) diameter placed at HO' (feet) on centers along the wall/ and 3' (Inches) .above finished surface. RETAINING WALL BACKFILL AND SUBDRAIN DETAIL GEOTEXTILE DRAIN DETAIL 2 Geotechnical • Geologic • Environmental DETAIL N . T , S . Provide surface drainage /4 or f later Native Backfill Slope or Level l)Water proving" menbrane (optional) Y 6) Weephole Finished surface Heel width 2) Clean sand backfill WATER PRDDFING MEMBRANE (optional)' Liquid boot or approved equivalent, © CLEAN SAND BACKFILL* Must have sand equivalent value of 30 or greaterj can be denslfled by water Jetting. © FILTER FABRICi Mlrafl 140N or approved equivalent. (4) RDCKi 1 cubic foot per linear feet of pipe of 3/4 to 1-1/2' (Inches) rock (5) PIPEi 4' (Inches) diameter perforated PVC. schedule 40 or approved alternative with Minimum of IX gradient to proper outlet point, (f) WEEPHDLEi Minimum 2* (Inches) diameter placed at SO' (feet) on centers along the wall, and 3* (Inches) above finished surface, RETAINING WALL AND SUBDRAIN DETAIL CLEAN SAND BACKFILL DETAIL 3 Geotechnical • Geologic • Environmental I I Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no greater than ± 100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes in walls higher than 2 feet should not be considered. The surface of the backfill should be sealed by pavement or the top 18 inches compacted with native soil (E.I. .<90). Proper surface drainage should also be provided. For additional mitigation, consideration should be given to applying a water-proof membrane to the back of all retaining structures. .The use of a waterstop should be considered for all concrete and masonry joints. Wall/Retaining Wail 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 17360 for a distance of 2H on either side of the transition may be accommodated. Expansion joints should be sealed with a flexible, non-shrink grout. c) Embed the footings entirely into native formational material (i.e., deepened footings). If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation "a" (above) and until such transition is between 45 and 90 degrees to the wall alignment. TOP-OF-SLOPEWALLS/FENCES/iMPROVEMENTS Expansive Soils and Slope Creep Soils at the site may 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 Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18, 2003 Rte:e:\wp9\3200\3213a.pge Page 28 GeoSofIs, Inc. c ru C [«•L "««• L r L» r L i—L 10 feet, this creep related soil movement will typically impact all rear yard flatwork and other secondary improvements that are located within about 15 feet from the top of slopes, such as swimming pools, concrete flatwork, etc., and in particular top of slope fences/walls. This influence is normally in the form of detrimental settlement, and tilting of the proposed improvements. The dessication/swelling and creep discussed above continues over the life of the improvements, and generally becomes progressively worse. Accordingly, the developer should provide this information to any homeowners and homeowners association. Top of Slope Walls/Fences Due to the potential for slope creep for slopes higher than about 10 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 forthe concrete and mortar should be provided along with the slump quantities. The concrete used should be appropriate to mitigate sulfate corrosion, as warranted. The design of the grade beam and caissons should be in accordance with the recommendations of the project structural engineer, and include the utilization of the following geotechnical parameters: Creep Zone: Creep Load: Point of Fixity: Passive Resistance: 5-foot vertical zone below the slope face and projected upward parallel to the slope face. The creep load projected on the area of the grade beam should be taken as an equivalent fluid approach, having a density of 60 pcf. For the caisson, it should be taken as a uniform 900 pounds per linear foot of caisson's depth, located above the creep zone. Located a distance of 1.5 times the caisson's diameter, below the creep zone. Passive earth pressure of 300 psf per foot of depth per foot of caisson diameter, to a maximum value of 4,500 psf may be used to determine caisson depth and spacing, provided that they meet or exceed the minimum requirements stated above. To determine the total lateral resistance, the contribution of the creep prone zone above the point of fixity, to passive resistance, should be disregarded. Mr. Edward E. Hagey APNs 155-140-37 and 155-140-38 Rte:e:\wp9\3200\3213a.pge GeoSotts, Inc. W.O.3213-A-SC September 18,2003 Page 29 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. DRIVEWAY. FLATWORK. AND OTHER IMPROVEMENTS The soil materials on site may be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to flatwork and other improvements. The resulting potential for distress to improvements may be reduced, but not totally eliminated. To that end, it is recommended that the developer should notify any homeowners or homeowners association of this long-term potential for distress. To reduce the likelihood of distress, the following recommendations are presented for all exterior flatwork: 1. The subgrade area for concrete slabs should be compacted to achieve a minimum 90 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 of the subgrade should be verified within 72 hours prior to pouring concrete. 2. Concrete slabs should be cast over a relatively non-yielding surface, consisting of a 4-inch layer of crushed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete. The layer should wet-down completely prior to pouring concrete, to minimize loss of concrete moisture to the surrounding earth materials. 3. Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and approaches should additionally have a thickened edge (12 inches) adjacent to all landscape areas, to help impede infiltration of landscape water under the slab. 4. The use of transverse and longitudinal control joints are recommended to help control slab cracking due to concrete shrinkage or expansion. Two ways to mitigate such cracking are: a) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and, b) provide an adequate amount of control and/or expansion joints to accommodate anticipated concrete shrinkage and expansion. In order to reduce the potential for unsightly cracks, slabs should be reinforced at mid-height with a minimum of No. 3 bars placed at 18 inches on center, in each direction. The exterior slabs should be scored or saw cut, Vz 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. Mr. Edward E. Hagey W.O.3213-A-SC APNs 155-140-37 and 155-140-38 September 18, 2003 F!te:e:\wp9\32DO\3ai3a.pge Page 30 GeoSotls, Inc. 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 wails should not be tied to the house. 8. Overhang structures should be supported on the slabs, or structurally designed with continuous footings tied in at least-two directions. 9. Any masonry landscape walls that are to be constructed throughout the property should be grouted and articulated in segments no more than 20 feet long. These segments should be keyed or doweled together. 10. Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. 11. Positive site drainage should be maintained at all times. Finish grade on the lots should provide a minimum of 1 to 2 percent fall to the street, as indicated herein. It should be kept 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. Mr. Edward E. Hagey ' W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Rte:e:\wp9\3200\3213a.pge Page 31 GeoSoils, Inc. DEVELOPMENT CRITERIA Slope Deformation Compacted fill slopes designed using customary factors of safety for gross or surficial stability and constructed in general accordance with the design specifications should be expected to undergo some differential vertical heave or settlement in combination with differential lateral movement in the out-of-slope direction, after grading. This post-construction movement occurs in two forms: slope creep, and lateral fill extension (LFE). Slope creep is caused by alternate wetting and drying of the fill soils which results in slow downslope movement. This type of movement is expected to occur throughout the life of the slope, and is anticipated to potentially affect improvements or structures (i.e., separations and/or cracking), placed near the top-of-slope, up to a maximum distance of approximately 15 feet from the top-of-slope, depending on the slope height. This movement generally results in rotation and differential settlement of improvements located within the creep zone. LFE occurs due to deep wetting from irrigation and rainfall on slopes comprised of expansive 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 Uniform Building Code and/or California Building Code), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. All of these measures are recommended for design of structures and improvements. The ramifications of the above conditions, and recommendations for mitigation, should be provided to each homeowner and/or any homeowners association. Slope Maintenance and Planting Water has been shown to weaken the inherent strength of all earth materials. Slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Over-watering should be avoided as it can adversely affect site improvements, and cause perched groundwater conditions. Graded slopes constructed 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 Mr. Edward E Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Fite:e:\wp0\3200\3213apge Page 32 GeoSoils, Inc. of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to each homeowner. Over-steepening of slopes should be avoided during building construction activities and landscaping. Drainage Adequate lot surface drainage is a very important factor in reducing the likelihood of adverse performance of foundations, hardscape, and slopes. Surface drainage should be sufficient to prevent ponding of water anywhere on a lot, and especially near structures and tops of slopes. Lot surface drainage should be carefully taken into consideration during fine grading, landscaping, and building construction. Therefore, care should betaken that future landscaping or construction activities do not create adverse drainage conditions. Positive site drainage within lots and common areas should be provided and maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should be directed away from foundations and not allowed to pond and/or seep into the ground. In general, the area within 5 feet around a structure should slope away from the structure. We recommend that unpaved lawn and landscape areas have a minimum gradient of one percent sloping away from structures, and whenever possible, should be above adjacent paved areas. Consideration should be given to avoiding construction of planters adjacent to structures (buildings, pools, spas, etc.). Pad drainage should be directed toward the street or other approved area(s). Although not a geotechnical requirement, roof gutters, down spouts, or other appropriate means may be utilized to control roof drainage. Down spouts, or drainage devices should outlet a minimum of 5 feet from structures or into a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy rainfall, and should be anticipated. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon request. Erosion Control Cut and fill slopes will be subject to surficial erosion during and after grading. Onsite earth materials have a moderate to high erosion potential. Consideration should be given to providing hay bales and silt fences for the temporary control of surface water, from a geotechnical viewpoint. Landscape Maintenance Only the amount of irrigation necessary to sustain plant life should be provided. Over-watering the landscape areas will adversely affect proposed site improvements. We would recommend that any proposed open-bottom planters adjacent to proposed structures be eliminated for a minimum distance of 10 feet. As an alternative, closed-bottom type planters could be utilized. An outlet placed in the bottom of the planter, could be installed to direct drainage away from structures or any exterior concrete flatwork. If planters are constructed adjacent to structures, the sides and bottom of the planter should be provided Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18. 2003 Rle:e:\wp9\3200\3213a.pge Page 33 GeoSofls, Inc. with a moisture barrier to prevent penetration of irrigation water into the subgrade. Provisions should be made to drain th& excess irrigation water from the planters without saturating the subgrade below or adjacent to the planters. Graded slope areas should be planted with drought resistant vegetation. Consideration should be given to the type of vegetation chosen and their potential effect upon surface improvements (i.e., some trees will have an effect on concrete flatwork with their extensive root systems). From a geotechnical standpoint leaching is not recommended for establishing landscaping. If the surface soils are processed for the purpose of adding amendments, they should be recompacted to 90 percent minimum relative compaction. Gutters and Downspouts As previously discussed in the drainage section, the installation of gutters and downspouts should be considered to collect roof water that may otherwise infiltrate the soils adjacent to the structures. If utilized, the downspouts should be drained into PVC collector pipes or non-erosive devices that will carry the water away from the house. Downspouts and gutters are not a requirement; however, from a geotechnical viewpoint, provided that positive drainage is incorporated into project design (as discussed previously). Subsurface and Surface Water Subsurface and surface water are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into final design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities may not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Groundwater conditions may change with the introduction of irrigation, rainfall, or other factors. Site improvements Recommendations for exterior concrete flatwork design and construction can be provided upon request. If in the future, any additional improvements (e.g., pools, spas, etc.) are planned for the site, recommendations concerning the geological or geotechnical aspects of design and construction of said improvements could be provided upon request. This office should be notified in advance of any fill placement, grading of the site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench, and retaining wall backfills. Mr. Edward E. Hagey W.O. 3213-A-SC APNs 155-140-37 and 155-140-38 September 18, 2003 Fite:e:\wp9\3200\3213apge Page 34 GeoSoils, Inc. I r I I r Tile Flooring Tile flooring can crack, reflecting cracks in the concrete slab below the tile, although small cracks in a conventional slab may not be significant. Therefore, the designer should consider additional steel reinforcement for concrete slabs-on-grade where tile will be placed. The tile installer should consider installation methods that reduce possible cracking of the tile such as slipsheets. Slipsheets or a vinyl crack isolation membrane (approved by the Tile Council of America/Ceramic Tile Institute) are recommended between tile and concrete slabs on grade. Additional Grading This office should be notified in advance of any fill placement, supplemental regrading of the site, or trench backfilling after rough grading has been completed. This includes completion of grading in the street and parking areas and utility trench and retaining wall backfills. Footing Trench Excavation AH footing excavations should be observed by a representative of this firm subsequent to trenching and prior to concrete form and reinforcement placement. The purpose of the observations is to verify that the excavations are made into the recommended bearing material and to the minimum widths and depths recommended for construction. If loose or compressible materials are exposed within the footing excavation, a deeper footing or removal and recompaction of thesubgrade materials would be recommended at that time. Footing trench spoil and any excess soils generated from utility trench excavations should be compacted to a minimum relative compaction of 90 percent, if not removed from the site. Trenching Considering the nature of the onsite soils, it should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Snoring or excavating the trench walls at the angle of repose (typically 25 to 45 degrees) may be necessary and should be anticipated. All excavations should be observed by one of our representatives and minimally conform to CAL-OSHA and local safety codes. Utility Trench Backfill 1. Ail interior utility trench backfill should be brought to at least 2 percent above optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard. As an alternative for shallow (12-inch to 18-inch) under-slab trenches, sand having a sand equivalent value of 30 or greater may be utilized and jetted or flooded into place. Observation, probing and testing should be provided to verify the desired results. Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 Rle:e:\wp9\3200^213a.pge Page 35 GeoSoi Is, Inc. 2. Exterior trenches adjacent to, and within areas extending below a 1:1 plane projected from the outside bottom edge of the footing, and all trenches beneath hardscape features and in slopes, should be compacted to at least 90 percent of the laboratory standard. Sand backfill, unless excavated from the trench, should not be used in these backfill areas. Compaction testing and observations, along with probing, should be accomplished to verify the desired results. 3. All trench excavations should conform to CAL-OSHA and local safety codes. 4. Utilities crossing grade beams, perimeter beams, or footings should either pass below the footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade beam in accordance with the recommendations of the structural engineer. SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend that observation and/or testing be performed by GSI at each of the following construction stages: • During grading/recertification. • After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. • Prior to pouring any slabs or flatwork, after presoaking/presaturation of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor barriers (i.e., visqueen, etc.). • During retaining wall subdrain installation, prior to backfill placement. • During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. • During slope construction/repair. When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed. Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18,2003 File:e:\wp9\3200\3213a.pge Page 36 GeoSoils, Inc. (Ml A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and clear documentation of site work, and/or to comply with code requirements. OTHER DESIGN PROFESSIONALS/CONSULTANTS The design civil engineer, structural engineer, post-tension designer, architect, landscape architect, wall designer, etc., should review the recommendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plans. PLAN REVIEW Final project plans should be reviewed by this office prior to construction, so that construction is in accordance with the conclusions and recommendations of this report. Based on our review, supplemental recommendations and/or further geotechnical studies maybe warranted. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty is expressed or implied. Standards of practice are subjectto change with time. GSI assumes no responsibility or liability for work ortesting performed by others, or their inaction, or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Mr. Edward E. Hagey W.0.3213-A-SC APNs 155-140-37 and 155-140-38 September 18.2003 Rle:eAwpe\3200\3213a.pge Page 37 GeoSoils, Inc. ttj_iiu><l--OZ g 8 S 8 8 e oi i i i i i i i <0 JU g I ffl « as ooooooooN. «o 10 ^ m e* -r- tito111 ocou. m IU ui111 U1-11UXI OZ — oo> (jeej) CD §H>(O o« UO!)BA»Q I IO O iLU l"? T <in m i a?o CO 2o 2 I aa.4 I* 1 cdJ e •• s s §U II Js£ > a £ U •=I xI 115 £ £ i I I I S 8 S 1 «T CO 5 M aS-s<r«ni2 ) APPEiSJPlXA REFERENCES APPENDIX A REFERENCES Benton Engineering, lnc.,1970, Rnal compaction report, La Costa South unit 7, August 10,1970, Project No. 69-12-8D. Blake, T.F., 2000a, EQFAULT, A computer program for the estimation of peak horizontal acceleration from 3-D fault sources; Windows 95/98 version. , 2000b, EQSEARCH, A computer program for the estimation of peak horizontal acceleration from California historical earthquake catalogs; Updated to December, 2002, Windows 95/98 version. , 2000c, FRJSKSP, A computer program for the probabilistic estimation of peak acceleration and uniform hazard spectra using 3-D faults as earthquake sources; Windows 95/98 version. Bozorgnia, Y., Campbell, K.W., and Niazi, M., 1999, Vertical ground motion: Characteristics, relationship with horizontal component, and building code implications; Proceedings of the SMIP99 seminar on utilization of strong-motion data, September 15, Oakland, pp. 23-49. Campbell, K.W. and Bozorgnia, Y., 1994, Near-source attenuation of peak horizontal acceleration from worldwide accelrograms recorded from 1957 to 1993; Proceedings, Fifth U.S. National Conference on Earthquake Engineering, volume III, Earthquake Engineering Research Institute, pp 292-293. GeoSoils, Inc., 1993, Preliminary geotechnical evaluation, parcel 155-140-09, Carlsbad, California, W.0.1624-SD, dated November 2. Hart, E.W. and Bryant, W.A. 1997, Fault-rupture Hazard Zones in California, Alquist-Priolo Earthquake Fault Zoning act with Index to Earthquake Fault Maps; California Division of Mines and Geology Special Publication 42. Idriss, I.M., 1994, Attenuation coefficients for deep and soft soil conditions; jn EQFAULT, A computer program for the estimation of peak horizontal acceleration from 3-D fault sources; Windows 95/98 version, Blake, 2000a. International Conference of Building Officials, 1997, Uniform building code: Whittier, California, vol. 1,2, and 3. Jennings, C.W., 1994, Fault activity map of California and adjacent areas: California Division of Mines and Geology, Map Sheet No. 6, scale 1:750,000. GeoSoils, Inc. Joyner, W.B., and Boore, D.M., 1982a, Estimation of response-spectral values as functions of magnitude, distance and site conditions, jn eds., Johnson, J A, Campbell, K.W., and Blake, T.F., AEG short course, seismic hazard analysis, dated June 18,1994. , 1982b, Prediction of earthquake response spectra, U.S. Geological Survey Open-Rle Report 82-977,16p. Kuhn, G.G., Legg, M.R., Johnson, JA, Shlemon, R.G., and Frost, E.G., 1996, Paleo liquefaction evidence for large pre-historic earthquakes(s) in north-coastal San Diego County, California, JQ Munasinghe, T., and Rosenberg, eds., Geology and natural resources of coastal San Diego County, California, guidebook to accompany the 1996 annual field trip of the San Diego Association of Geologists, September. Obermeier, S.F., 1996, Using liquefaction-induced features for paleoseismic analysis, Chapter 7, in McCalpin, J.P., ed, Paleoseismology, Acedemic Press Petersen, Mark D., Bryant, WA, and Cramer, C.H., 1996, Interim table of fault parameters used by the California Division of Mines and Geology to compile the probabilistic seismic hazard maps of California. Sadigh, K., Egan, J., and Youngs, R., 1987, Predictive ground motion equations reported in Joyner, W.B., and Boore, D.M., 1988, "Measurement, characterization, and prediction of strong ground motion," JQ Earthquake Engineering and Soil Dynamics II, Recent Advances in Ground Motion Evaluation, Von Thun, J.L, ed.: American Society of Civil Engineers Geotechnical Special Publication No. 20, pp. 43-102. Tan, S.S., and Kennedy, Michael P., 1996, Geologic maps of the northwestern part of San Diego County, California: California Division of Mines and Geology, Open File Report 96-02. Mr. Edward H. Hagey Appendix A Bte:e:\wp9\3200\3213a.pge Page 2 GeoSoils, Inc. APPENDIX B EXPLORATIONS GeoSoils, Inc. PROJECTOR. TED HAGEY BORING LOG W.O. 3213-A-SC BORING B-1 SHEET 1 OF 1 APNs 155-140-37 and 155-140-38, City of Carlsbad DATE EXCAVATED 1-9-02 Depth (ft.)_ Sample 3m II m §1 SM SM Dry Unit WL(pof)Moisture (%)£ i SAMPLE METHOD: HAND AUGER i| Standard Penetration Test -V. nmnnilvrafar '<0A Undisturbed, Ring Sample Description of Material >*• .-"? w—LA is; ARTIFICIAL FILL: @ 0-4' SILTY SAND, brown, damp to moist, loose; rootlets. TERRACE DEPOSITS: @ 4-5' SILTY SAND, reddish brown, slightly moist, medium dense. Total Depth = 5' No Groundwater Encountered Backfilled 1-9-2002 APNs 155-140-37 and 155-140-38, City of Carlsbad vaeOoOIIS, IRC. PMTE B"1 GeoSoils, Inc. PROJECTOR. TED HAGEY BORING LOG W.O. 3213-A-SC BORING B-2 SHEET 1 OF 1 APNs 155-140-37 and 155-140-38, City of Carlsbad DATE EXCAVATED 1-WJ2 g - 5- Sample £ ffl I I II I CO i! SM SM Dry Unit Wt(pof)107.0 Moteture (%)5.1 Saturation (%)24.7 SAMPLE METHOD: HAND AUGER Hiis_< ofanaaro Penetration Test j£ Groundwater %jA Undisturbed, Ring Sample Description of Material .s?. s^ * ^r> . tr* y7 ' >>> .V*.0* •JJ7 ' w^ !^^« ' ^x?'' .>> .t^ •y?t^ . v*.i^ •>>^1 J«- .^*- • y7 .W" " • '•**** ' *» , ARTIFICIAL FILL: @ 0-1" SILTY SAND, brown, damp, loose; rootlets. TERRACE DEPOSITS: @ 1-4' SILTY SAND, reddish brown, moist, medium dense to dense with depth. Total Depth = 4' No Groundwater Encountered Backfilled 1-9-2002 APNs 155-140-37 and 155-140-38, City of Carlsbad oeOoOIIS, IRC. PLATE B-2 GeoSoils, Inc. PRO/ECT;MR- TED HAGEY BORING LOG W.O. 3213-A-SC BORING B-3 SHEET 1 OF 1 APNs 155-140-37 and 155-140-38, City of Cartsbad DATE EXCAVATED 1-9-02 Depth (ft.)5- Sample g m ii , D m SM Dry Unit Wt(pcO&Saturation (%)SAMPLE METHOD: HAND AUGER iI Standard Penetration Tost __ ^ Groundwateryfy Undisturbed, Ring Sample Description of Material .X"\,:_^, >*T' .i/^-. V1?* " w^";^.i>*->>?; !H"!.L^-. •>jr" COLLUV1UM/TOPSOIL: @ 0-2' SILTY FINE SAND, brown, dry, loose; well rounded coarse pebbles. SANTIAGO FORMATION (TSA): @ 2-3' CLAYEY SANDSTONE, redish brown to light brown, moist, medium dense. @ 3-4V41 grades to SANDSTONE, light brown, moist, dense. Total Depth = 41/2' No Groundwater Encountered Backfilled 1-9-2002 f^^piOfNiin Inf* APNs 155-140-37 and 155-140-38, Ctty of Carlsbad vjcuowno, inv. PLATE B-3 GeoSoils, Inc. PROJECT/MR- TED HAGEY BORING LOG W.O. 3213-A-SC BORING B-4 SHEET 1 OF 1 APNs 155-140-37 and 155-140-38. City of Carlsbad DATE EXCAVATED 1-9-02 Depth (n.)5" Sample ,43 j 81 §1 SM SM Dry Unit WL.(pof)Moisture (%)Saturation (%)SAMPLE METHOD: HAND AUGER II Standard Penetration Test v GroundwstBr% Undisturbed, Ring Sample Description of Material :£ .LA yT 'i>7 . '+S*- ' •y? '.'*>? . COLLUVIUM: @ 0-1%' SILTY SAND, brown, dry, loose; rootles. OLDER ALLUVIUM: @ r/t-5' SILTY FINE SAND, reddish brown, moist, loose to medium dense. Total Depth = 5' No Groundwater Encountered Backfilled 1-9-2002 APNs 155-140-37 and 155-140-38. Cfty of Carlsbad oeObOllS, IHC. PLATE B-4 GeoSoils, Inc. PROJECTOR. TED HAGEY BORING LOG W.O. 3213-A-SC BORING B-5 SHEET 1 OF 1 APNs 155-140-37 and 155-140-38, CHy of Carlsbad DATE EXCAVATED 1-9-02 Depth (ft.)- 5- Sample 1ID 4«1133 Q 3 W SM Dry Unit Wt(pof)Moisture (%)£ SAMPLE METHOD: HAND AUGER I K# 3 Standard Penetration TestQ -V. Gioundwster £ Undisturbed, Ring Sampfe Description of Material ^r.^>- •*>~'•j*" .5-^- •^7- !^"LA >Sr- ' \s* • w"- V7 «J«** COLLUVIUM/TOPSOIL: @ 0-2' SILTY SAND, brown, dry, loose; rootlets, rounded coarse pebbles. SANTIAGO FORMATION (ISA): @ 2-4' CLAYEY SANDSTONE, reddish brown to light brown, moist, loose to medium dense. Total Depth = 4' No Groundwater Encountered Backfilled 1-9-2002 APNs 155-140-37 and 155-140-38. City of Carlsbad oeObOllS, mC. PLATE B-5 GEOSOILS, INC. BORING LOG CLIEMT.MICHAEL REED ______ WORK ORDER NO. PARCEL 155-140-09, CARLSBAD DATE EXCAVATED SAMPLE METHOD AUGER DRILLING RIG BORIMG MO. B-l 30" DIAMETER BUCKET 1624-SD 10-21-93 SHEET 1 OF 2 1- s:+• 0.0Q _ — - - i nJ.U - - 15- : - r* n20- - - - 25- ~_ 30- - - 35- - Sj i£ —3m • •••• •I• • . AMI i -a — .DTJ L. C 33-t-z ^n ^ ^ ^p M\ b 3LE 2 (D a 3 O ffl _ 1 4 1 10 20 0 M -D U EW 3>3 M SM CMO^i. SM SP +• i!u. 3)L O 123 3J. b — * • «J 111.5 100.0 125.3 ^f 128.2 118.5 f J a L. _35*• 5n.— OE 7 4r • *± 5.4 4.2 11.4 * ^10.3 14.0 3 I ^r;; ;; ; \ ', '. ' l {•:|!{; ij |1 [: :j| S ~ — ^S ::;Hi I 1 •:| ?•; -^:: •• i": ; ; II ;; ^ ^;; :: • * ;=: jt 111 :jj i| :;[ ^^s ~ II ij J i| ;l 1 DESCRIPTION OF MATERIAL 0-1' TOPSQIL; Dark yellowish brown silty "\SAND; dry, loose, hard and porous, trace [ \rootlets . / @1' TERRACE DEPOSITS (Ot) ; Reddish brown silty SAND; slightly moist, medium dense. @2' Becomes moist. Is' Yellowish brown fine SAND with some silt; slightly moist, medium dense. 610' Brownish yellow, clean fine SAND with trace well rounded pebbles; slightly moist and medium dense. @13. 5 ' Grades to clean fine SAND with well rounded cobbles. @15' Becomes fine SAND. "Vgie' Abrupt, approximately horizontal basal/" \contact. / @16' SANTIAGO FORMATION (Tsaj : Light gray SANDSTONE with trace clay; moist and medium dense to dense. ©IS'-W Zone of slight water seepage into boring. @19' Sandstone becomes denser. A o o c / A Vx ^ • n y\^>" sa Tnt^ sa 'f'M \"v*f*w { Tn?%"^ ^^ t xr Vt fk^*^ ^^%T^4~s> 1e«i-j.~> Ajjjrupu, cinu appiroximciuexy norizonuai contact of &ANDSTONE over light olive brown sandy CLAYSTONE; slightly moist and very stiff, with randomly oriented irregular "\ptJJ. XSIJ.6CI J.XTaO L.L1XT6 SU.XTl.a.L'6S • f @27'-28' Gradational, approximately horizontal transitional zone from claystone to light gray SANDSTONE; moist and dense. @33' Observed water seepage into hole from near vertical fracture in SANDSTONE, fracture trends north 35 degrees east. @34' Becomes very moist, slight seepage from boring sidewalls observed to bottom of boring. FORM 88/9 Plate B-6 GEOSOILS, INC. BORING LOG CLIENT.MICHAEL REED WORK ORDER NO. PARCEL 155-140-09, CARLSBAD DATE EXCAVATED SAMPLE METHOD AUGER DRILLING RIG BORING MO. B-l 30" DIAMETER BUCKET 1624-SD 10-21-93 SHEET 2 OF 2 £ 0.0 O - - /I R-4tO - 50- - 55- - 60- 65- 70- 75- SAMPLE yi —3ffl 1 T• I •0 Lr 3 ^ '//// '///s s CDN 3O^m 30 6" .-o M XI O 6M 31 3 W 4- 3 4- 1- fi^ O(L 5 L Q 121.9 -iiW aL _35•*• i*~ 0E 13.0 *ie c DESCRIPTION OF MATERIAL I I-!;! Ill Ijiij !•• i i; : i: !illz^r: === jjjjjj -.652' Increased seepage into boring from /- \SANDSTONE. / •\@52.5' Olive brown fractured claystone; r i slightly moist to moist and very stiff. /r 654' Light yellow gray SANDSTONE; moist to / very moist, dense. _J Total depth= 55 feet Seepage at 18 to 19 feet and below 34 feet Increased seepage at 52 feet No caving Hole backfilled FORM B8/9 Plate B-7 HAND AUGER LOG Hand Auger Depth (ft.) Material Description HA-1 0-1 TOPSOIL: Yellowish brown sitty fine SAND; dry, loose, porous, friable, few rootlets. 1-1.5 TERRACE DEPOSITS fQtt: Red brown silty SAND; slightly moist, loose to medium dense, slightly hard. 1.5-2 Becomes slightly motet to moist and medium dense. Total depth= 2 feet No groundwater Hole backfilled HA-2 0-1 COLLUVIUM: Brown sandy SILT; dry, loose, few roots. 1-2 TERRACE DEPOSITS fQtt: Red brown fine SAND with some well rounded pebbles; slightly moist, loose to medium dense, friable. 2-7 SANTIAGO FORMATION fTsa): Light yellow gray fine grained SANDSTONE; slightly moist to moist, medium dense. Total depth = 7 feet No groundwater Hole backfilled Plate B-8 MR. MICHAEL REED W.O. 1624-SD NOVEMBER 2, 1993 HAND AUGER LOG Hand Auger Depth (ft.)Material Description HA-3 0-2 2-3 3-8 COLLUVIUM: Dark brown silty fine SAND with some well rounded coarse pebbles; dry, loose. SANTIAGO FORMATION (Tsa): Red brown SANDSTONE with some clay; moist, loose to medium dense. Grades to yellow brown SANDSTONE; moist, medium dense. Total depth = 8 feet No groundwater Hole backfilled HA-4 0-1.5 1.5-7.5 7.5-8 COLLUVIUM: Brown silty SAND; dry and loose. OLDER ALLUVIUM fQoa): Red brown silty fine SAND; moist, loose to medium dense. SANTIAGO FORMATION fTsa): SANDSTONE; moist, medium dense. Total depth = 8 feet No groundwater Hole backfilled Yellow brown Plate B-9 APPENDIX C EQFAULT, EQSEARCH, AND FRISKSP co "-4-J CO 0oo MAXIMUM EARTHQUAKES Hagey Residence 1 .1 .01 .001 .1 X X X Illl 1 10 Distance (mi) X X 100 W.O. 3213-A-SC Plate C-1 EARTHQUAKE RECURRENCE CURVE Hagey Residence IUU ~ 10 - i_ CO '•""• AZ in•*-> 5HI ? .1-ative Numberb-AiE E O 001 - | MIL \ ^*^SJ Mil §| "^^^ ^X MM k ""•»«•,-i ^^± ^^v 1 INI r^*^ < JJUUL ^ i < NM •^ta^^ "^^^ > 1 1 1 1 J=LLL 5^JX MM 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 Magnitude (M) W.O. 3213-A-SC Plate C-2 1100 1000 - - 900 - -, 800 - - 700 - - 600 -- 500 -- 400 - 300 - 200 - 100- 0 - EARTHQUAKE EPICENTER MAP Hagey Residence -100 -400 -300 -200 -100 100 200 300 400 500 600 W.O. 3213-A-SC Plate C-3 PROBABILITY OF EXCEEDANCE BOZ. ET AL(1999)HOR SR UNC 1 100 90 CO 0oc CO TJ 0 0 O X LU 20 10 0 75 yrs 100 yrs 0.00 0.25 0.50 0.75 1.00 1.25 Acceleration (g) 1.50 W.O. 3213-A-SC Plate C-4 zO H- LJJ O N O X. D a: \ \ O O O O W.O. 3213-A-SC \ oooo ooo oo (SJX) O LO CM O 9 ,3 c. O co O O 0< IO CM Plate C-5 RETURN PERIOD vs. ACCELERATIONBOZ. ET AL.(1999)HOR SR UNC 1\ \ y 100000 -t V s H S i- ooo v ^ss\ O O O x — s s•k \\ • \. oo 1 >>»>-«s — — — •^•s 0 LO LO CM o C~> rr\. D) c "^3 LO CO • 0 CDO0 0< LO o LO CM *0 or} 0 (sjA) APPENDIX D UBORATORY DATA 03 § £q 5 to • • 3,000 2,500 2,000 1 1 1.500 ro. <n 1,000 500 0. 0 •ry,,. . • " • -* ':.-:'- • ^ . .; Sample B-1 B-1 •^^ • . : < •^^ ' . •••'; ('• ':• " '.'.'?•' . 500 1,000 1,500 2,000 NORMAL PRESSURE, psf Depth/EL 0.0 0.0 Primary/Residual Shear Primary Shear Residual Shear Sample Type Remolded Remolded % 107.9 107.9 ; -, . : •-.r- ;.. - ••;i: ;•:';;."•-• .2,500 MC% 5.1 5.1 . ,3,000 c 317 275 4> 33 33 Note: Sample Innundated prior to testing GeoSoils. Inc. j^&t^&ato 5741 Palmer Way Capllpljtel^ Carlsbad, CA 92008 %ar$wP»S, Telephone: (760)438-3155 Fax: DIRECT Project: HAGEY Number: 3213-A-SC Date: January 2002 SHEAR TEST Plate ro-1 APPENDIX E SLOPE STABILITY ANALYSIS «• 2-DIMENSIONAL SLOPE STABILITY ANALYSIS INTRODUCTION OF GSTABL7 v.2 COMPUTER PROGRAM Introduction GSTABL7 v.2 is a fully integrated slope stability analysis program. It permits the engineer to develop the slope geometry interactively and perform slope stability analysis from within a single program. The slope analysis portion of GSTABL7 v.2 uses a modified version of the popular STABL program, originally developed at Purdue University. GSTABL7 v.2 performs a two dimensional limit equilibrium analysis to compute the factor of safety for a layered slope using the simplified Bishop or Janbu methods. This program can be used to search for the most critical surface or the factor of safety may be determined for specific surfaces. GSTABL7, Version 2, is programmed to handle: 1. Heterogenous soil systems 2. Anisotropic soil strength properties 3. Reinforced slopes 4. Nonlinear Morir-Coulomb strength envelope 5. Pore water pressures for effective stress analysis using: a. Phreatic and piezometric surfaces b. Pore pressure grid c. R factor d. Constant pore water pressure 6. Pseudo-static earthquake loading 7. Surcharge boundary loads 8. Automatic generation and analysis of an unlimited number of circular, noncircular and block-shaped failure surfaces 9. Analysis of right-facing slopes 10. Both SI and Imperial units General Information If the reviewer wishes to obtain more information concerning slope stability analysis, the following publications may be consulted initially: 1. The Stability of Slopes, by E.N. Bromhead, Surrey University Press, Chapman and Hall, N.Y., 411 pages, ISBN 412 01061 5,1992. 2. Rock Slope Engineering, by E. Hoek and J.W. Bray, Inst. of Mining and Metallurgy, London, England, Third Edition, 358 pages, ISNB 0 900488 573,1981. 3. Landslides: Analysis and Control, by R.L Schuster and R. J. Krizek (editors), Special Report 176, Transportation Research Board, National Academy of Sciences, 234 pages, ISBN 0 309 02804 3,1978. GeoSoils, Inc. GSTABL7 v.2 Features•*•» *" The present version of GSTABL7 v.2 contains the following features: 1. Allows user to calculate factors of safety for static stability and dynamic stability m situations. •*• 2. Allows user to analyze stability situations with different failure modes. „ 3. Allows user to edit input for slope geometry and calculate corresponding factor of safety.m „ 4. Allows user to readily review on-screen the input slope geometry. 5. Allows user to automatically generate and analyze unlimited number of circular, - non-circular and block-shaped failure surfaces (i.e., bedding plane, slide plane, etc.). Input Data — Input data includes the following items: - 1. Unit weight, residual cohesion, residual friction angle, peak cohesion, and peak — friction angle of fill material, bedding plane, and bedrock, respectively. Residual cohesion and friction angle is used for static stability analysis, where as peak - cohesion and friction angle is for dynamic stability analysis. (0 2. Slope geometry and surcharge boundary loads. *m ^ 3. Apparent dip of bedding plane can be specified in angular range (i.e., from 0 to 90 degrees. **m» M 4. Pseudo-static earthquake loading (an earthquake loading of 0.12 / was used in the analysis). «• Seismic Discussion " Seismic stability analyses were approximated using a pseudo-static approach. The major *• difficulty in the pseudo-static approach arises from the appropriate selection of the seismic coefficient used in the analysis. The use of a static inertia force equal to this acceleration """ during an earthquake (rigid-body response) would be extremely conservative for several *» reasons including: (1) only low height, stiff/dense embankments or embankments in i confined areas may respond essentially as rigid structures; (2) an earthquake's inertia force is enacted on a mass for a short time period. Therefore, replacing a transient force by a «P pseudo-static force representing the maximum acceleration is considered unrealistic; (3) j Assuming that total pseudo-static loading is applied evenly throughout the embankment T Mr. Edward H. Hagel Appendix E | R!e:e:\wp9\3200\3213a.pge Page 2 GeoSoils, Inc. for an extended period of time is an incorrect assumption, as the length of the failure surface analyzed is usually much greater than the wave length of seismic waves generated by earthquakes; and (4) the seismic waves would place portions of the mass in compression and some in tension, resulting in only a limited portion of the failure surface analyzed moving in a downslope direction, at any one instant of time. The method developed by Krinitzsky, Gould, and Edinger (1993) which was in turn based on Taniguchi and Sasaki, 1986 (T&S, 1986), was referenced. This method is based on empirical data and the performance of existing earth embankments during seismic loading. Our review of "Guidelines for Evaluating and Mitigating Seismic Hazards in California (Davis, 1997) indicates the State of California recommends using pseudo-static coefficient of 0.15 for design earthquakes of M 8.25 or greater and using 0.1 for earthquake parameter M 6.5. Therefore, for conservatism a seismic coefficient of 0.12 / was used in our analysis. Output information Output information includes: 1. All input data. 2. Factorsofsafetyforthetenmostcrrticalsurfacesforstaticand pseudo-static stability situation. 3. High quality plots can be generated. The plots include the slope geometry, the critical surfaces and the factor of safety. 4. Note, that in the analysis, a minimum of 100 trial surfaces were analyzed for each section for either static or pseudo-static analyses. Results of Slope Stability Calculation Table E-1 shows parameters used in slope stability calculations. Summaries of the slope stability analysis are presented in Table E-2. Detailed output information is presented in Plates E-1 to E-4. A typical cross-section representing the highest proposed fill slope at a gradient of 2:1 (h:v) was utilized for analyses. Mr. Edward H. Hagel Appendix E RlKe:\wp9\3200\3213a.pge Page 3 GeoSofls, Inc. TABLE E-1 SOIL PARAMETERS USED Older Alluvium 250 28 Terrace Deposits 200 32 Santiago Formation Aniso Aniso TABLE E-2 SUMMARY OF SLOPE ANALYSIS • H' Hr ill r,- ISM,C! Gross ±65-Foot High Native Slope 2.5:1 to 4.5:1 2.80 2.00 Gross ±65-Foot High Native Slope £5:1 to 4.5:1 2.12 1.54 Mr. Edward H. Hagel File:e:\wp9\3200\3213a.pge GeoSotts, Inc. Appendix E Page 4 • **r(O ^ CQ w 22o ° H m1 U §UJ ce PO I! CO C « . °1 C^ coco cooooooooocooooo^ O X> » «- D)£ -- • oin § Oin OOCM tJO | | w m •og=^1c S EJcoir"-tcv| CO > TJsi§3kxo° Oin 4 fi I oo oin oinCM oin o 3 oin W.O. 3213-A-SC Plate E-1 iiUJ g (O S in"3CQ o CO wiCO 3 o jg-goooo Q. 3Z > WO-HOiSSUa CM g §co oin 0o •ooI Q. O J2ffi •o 8CM 00 O i 2 I £ I oo04 Om oo W.O. 3213-A-SC Plate E-2 O i CO Q <N 5CO I 1* $•§0000 CL 3Z V) .o^-SqgqJflsis «>.-.ooqiStesa*~"~ a —!£0 O"O (D1*- OIJC IOCM s W.O. 3213-A-SC Plate E-3 oii (0 CO 01 oW » DO o ' OS)UJ CM 5 «| UJ ggl< o TJ LQ2"? wQ •£• o V) o •»o- ow o>»- oox: — —. CM i o8 o A I DL 8<*> *r •o£ Jo C 3 OO Oin in oJC XI.1 mO I !2 10u. 0) oto W.O. 3213-A-SC Plate E-4 ,. -; ;•.,•";;-;:;:'- APPENDIX F .'v'-:c': -: GENERAL EARTHWORK AND GRADING GUIDELINES GENERAL EARTHWORK AND GRADING GUIDELINES General These guidelines present general procedures and requirements for earthwork and grading as shown on the approved grading plans, including preparation of areas to filled, placement of fill, installation of subdrains and excavations. The recommendations contained in the geotechnical report are part of the earthwork and grading guidelines and would supercede the provisions contained hereafter in the case of conflict. Evaluations performed by the consultant during the course of grading may result in new recommendations which could supersede these guidelines or the recommendations contained in the geotechnical report. The contractor is responsible for the satisfactory completion of all earthwork in accordance with provisions of the project plans and specifications. The project soil engineer and engineering geologist (geotechnical consultant) or their representatives should provide observation and testing services, and geotechnical consultation during the duration of the project. EARTHWORK OBSERVATIONS AND TESTING Geotechnical Consultant Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer and engineering geologist) should be employed for the purpose of observing earthwork procedures and testing the fills for conformance with the recommendations of the geotechnical report, the approved grading plans, and applicable grading codes and ordinances. The geotechnical consultant should provide testing and observation so that determination may be made that the work is being accomplished as specified. It is the responsibility of the contractor to assist the consultants and keep them apprised of anticipated work schedules and changes, so that they may schedule their personnel accordingly. All clean-outs, prepared ground to receive fill, key excavations, and subdrains should be observed and documented by the project engineering geologist and/or soil engineer prior to placing and fill. It is the contractor's responsibility to notify the engineering geologist and soil engineer when such areas are ready for observation. Laboratory and Field Tests Maximum dry density tests to determine the degree of compaction should be performed in accordance with American Standard Testing Materials test method ASTM designation D-1557-78. Random field compaction tests should be performed in accordance with test method ASTM designation D-1556-82, D-2937 or D-2922 and D-3017, at intervals of approximately 2 feet of fill height or every 100 cubic yards of fill placed. These criteria would vary depending on the soil conditions and the size of the project. The location and frequency of testing would be at the discretion of the geotechnical consultant. GeoSoils, Inc. Contractor's Responsibility All clearing, site preparation, and earthwork performed on the project should be conducted by the contractor, with observation by geotechnical consultants and staged approval by the governing agencies, as applicable. It is the contractor's responsibility to prepare the ground surface to receive the fill, to the satisfaction of the soil engineer, and to place, spread, moisture condition, mix and compact the fill in accordance with the recommendations of the soil engineer. The contractor should also remove all major non-earth material considered unsatisfactory by the soil engineer. It is the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the earthwork in accordance with applicable grading guidelines, codes or agency ordinances, and approved grading plans. Sufficient watering apparatus and compaction equipment should be provided by the contractor with due consideration for the fill material, rate of placement, and climatic conditions. If, in the opinion of the geotechnical consultant, unsatisfactory conditions such as questionable weather, excessive oversized rock, or deleterious material, insufficient support equipment, etc., are resulting in a quality of work that is not acceptable, the consultant will inform the contractor, and the contractor is expected to rectify the conditions, and if necessary, stop work until conditions are satisfactory. During construction, the contractor shall properly grade all surfaces to maintain good drainage and prevent ponding of water. The contractor shall take remedial measures to control surface water and to prevent erosion of graded areas until such time as permanent drainage and erosion control measures have been installed. SITE PREPARATION All major vegetation, including brush, trees, thick grasses, organic debris, and other deleterious material should be removed and disposed of off-site. These removals must be concluded prior to placing fill. Existing fill, soil, alluvium, colluvium, or rock materials determined by the soil engineer or engineering geologist as being unsuitable in-place should be removed prior to fill placement. Depending upon the soil conditions, these materials may be reused as compacted fills. Any materials incorporated as part of the compacted fills should be approved by the soil engineer. Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic tanks, wells, pipelines, or other structures not located prior to grading are to be removed or treated in a manner recommended by the soil engineer. Soft, dry, spongy, highly fractured, or otherwise unsuitable ground extending to such a depth that surface processing cannot adequately improve the condition should be overexcavated down to firm ground and approved by the soil engineer before compaction and filling operations continue. Overexcavated and processed soils which have been property mixed and moisture conditioned should be re-compacted to the minimum relative compaction as specified in these guidelines. Mr. Edward H. Hagey Appendix F Fite:e:\wp9\3200\3213a.pge Page 2 GeoSoils, Inc. Existing ground which is determined to be satisfactory for support of the fills should be scarified to a minimum depth of 6 inches or as directed by the soil engineer. After the scarified ground is brought to optimum moisture content or greater and mixed, the materials should be compacted as specified herein. If the scarified zone is grater that 6 inches in depth, it may be necessary to remove the excess and place the material in lifts restricted to about 6 inches in compacted thickness. Existing ground which is not satisfactory to support compacted fill should be overexcavated as required in the geotechnical report or by the on-site soils engineer and/or engineering geologist. Scarification, disc harrowing, or other acceptable form of mixing should continue until the soils are broken down and free of large lumps or clods, until the working surface is reasonably uniform and free from ruts, hollow, hummocks, or other uneven features which would inhibit compaction as described previously. Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical), 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 soil engineer and/or engineering geologist. In fill over cut slope conditions, the recommended minimum width of the lowest bench or key is also 15 feet with the key founded on firm material, as designated by the Geotechnical Consultant. As a general rule, unless specifically recommended otherwise by the Soil Engineer, the minimum width of fill keys should be approximately equal to 1/2 the height of the slope. Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable material. Benching may be used to remove unsuitable materials, although it is understood that the vertical height of the bench may exceed 4 feet. Pre-stripping may be considered for unsuitable materials in excess of 4 feet in thickness. All areas to receive fill, including processed areas, removal areas, and the toe of fill benches should be observed and approved by the soil engineer and/or engineering geologist prior to placement of fill. Fills may then be properly placed and compacted until design grades (elevations) are attained. COMPACTED FILLS Any earth materials imported or excavated on the property may be utilized in the fill provided that each material has been determined to be suitable by the soil engineer. These materials should be free of roots, tree branches, other organic matter or other deleterious materials. All unsuitable materials should be removed from the fill as directed by the soil engineer. Soils of poor gradation, undesirable expansion potential, or substandard strength characteristics may be designated by the consultant as unsuitable and may require blending with other soils to serve as a satisfactory fill material. Mr. Edward H. Hagey Appendix F FIte:e:\wp9\3200\3213a.pge Page 3 GeoSoils, Inc. Rli materials derived from benching operations should be dispersed throughout the fill area and blended with other bedrock derived material. Benching operations should not result in the benched material being placed only within a single equipment width away from the fill/bedrock contact. Oversized materials defined as rock or other irreducible materials with a maximum dimension greater than 12 inches should not be buried or placed in fills unless the location of materials and disposal methods are specifically approved by the soil engineer. Oversized material should be taken off-site or placed in accordance with recommendations of the soil engineer in areas designated as suitable for rock disposal. Oversized material should not be placed within 10 feet vertically of finish grade (elevation) or within 20 feet horizontally of slope faces. To facilitate future trenching, rock should not be placed within the range of foundation excavations, future utilities, or underground construction unless specifically approved by the soil engineer and/or the developers representative. If import material is required for grading, representative samples of the materials to be utilized as compacted fill should be analyzed in the laboratory by the soil engineer to determine its physical properties. If any material other than that previously tested is encountered during grading, an appropriate analysis of this material should be conducted by the soil engineer as soon as possible. Approved fill material should be placed in areas prepared to receive fill in near horizontal layers that when compacted should not exceed 6 inches in thickness. The soil engineer may approve thick lifts if testing indicates the grading procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each layer should be spread evenly and blended to attain uniformity of material and moisture suitable for compaction. Fill layers at a moisture content less than optimum should be watered and mixed, and wet fill layers should be aerated by scarification or should be blended with drier material. Moisture condition, blending, and mixing of the fill layer should continue until the fill materials have a uniform moisture content at or above optimum moisture. After each layer has been evenly spread, moisture conditioned and mixed, it should be uniformly compacted to a minimum of 90 percent of maximum density as determined by ASTM test designation, D-1557-78, or as otherwise recommended by the soil engineer. Compaction equipment should be adequately sized and should be specifically designed for soil compaction or of proven reliability to efficiently achieve the specified degree of compaction. 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 Mr. Edward H. Hagey Appendix F Rle:e:\wp9\3200\3213a.pge Page 4 GeoSoils, lite. tested and found to meet the density and moisture requirements, and is approved by the soil engineer. Compaction of slopes should be accomplished by over-building a minimum of 3 feet horizontally, and subsequently trimming back to the design slope configuration. Testing shall be performed as the fill is elevated to evaluate compaction as the fill core is being developed. Special efforts may be necessary to attain the specified compaction in the fill slope zone. Final slope shaping should be performed by trimming and removing loose materials with appropriate equipment. A final determination 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 (horizontal to vertical), specific material types, a higher minimum relative compaction, and special grading procedures, may be recommended. If ah 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. 3. Field compaction tests will be made in the outer (horizontal) 2 to 8 feet of the slope at appropriate vertical intervals, subsequent to compaction operations. 4. After completion of the slope, the slope face should be shaped with a small tractor and then re-rolled with a sheepsfoot to achieve compaction to near the slope face. Subsequent to testing to verify compaction, the slopes should be grid-rolled to achieve compaction to the slope face. Final testing should be used to confirm compaction after grid rolling. 5. Where testing indicates less than adequate compaction, the contractor will be responsible to rip, water, mix and re-compact the slope material as necessary to achieve compaction. Additional testing should be performed to verify compaction. 6. Erosion control and drainage devices should be designed by the project civil engineer in compliance with ordinances of the controlling governmental agencies, and/or in accordance with the recommendation of the soil engineer or engineering geologist. Mr. Edward H. Hagey Appendix F Rle:e:\wp9\3200\3213a.pge Page 5 GeoSof Is, Inc. 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 soil engineer and/or engineering geologist may recommend and direct changes in subdrain line, grade and drain material in the field, pending exposed conditions. The location of constructed subdrains should be recorded by the project civil engineer. EXCAVATIONS Excavations and cut slopes should be examined during grading by the engineering geologist. If directed by the engineering geologist, further excavations or overexcavation and re-filling of cut areas should be performed and/or remedial grading of cut slopes should be performed. When fill over cut slopes are to be graded, unless otherwise approved, the cut portion of the slope should be observed by the engineering geologist prior to placement of materials for construction of the fill portion of the slope. The engineering geologist should observe all cut slopes and should be notified by the contractor when cut slopes are started. If, during the course of grading, unforeseen adverse or potential adverse geologic conditions are encountered, the engineering geologist and soil engineer should investigate, evaluate and make recommendations to treat these problems. The need for cut slope buttressing or stabilizing should be based on in-grading evaluation by the engineering geologist, whether anticipated or not. Unless otherwise specified in soil and geological reports, no cut slopes should be excavated higher or steeper than that allowed by the ordinances of controlling governmental agencies. Additionally, short-term stability of temporary cut slopes is the contractors responsibility. Erosion control and drainage devices should be designed by the project civil engineer and should be constructed in compliance with the ordinances of the controlling governmental agencies, and/or in accordance with the recommendations of the soil engineer or engineering geologist. 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 filled areas are graded in accordance with the approved project specifications. After completion of grading and after the soil engineer and engineering geologist have finished their observations of the work, final reports should be submitted subject to review Mr. Edward H. Hagey Appendix F File:e:\wp9\3200\3213a.pge Page 6 GeoSoils, Inc. by the controlling governmental agencies. No further excavation or filling should be undertaken without prior notification of the soil engineer and/or engineering geologist. All finished cut and fill slopes should be protected from erosion and/or be planted in accordance with the project specifications and/or as recommended by a landscape architect. Such protection and/or planning should be undertaken as soon as practical after completion of grading. JOB SAFETY General At GeoSoils, Inc. (GSI) getting the job done safely is of primary concern. The following is the company's safety considerations for use by all 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 contractors regularly scheduled and documented safety meetings. Safety Vests: Safety vests are provided for and are to be worn by GSI personnel at all times when they are working in the field. Safety Flags: Two safety flags are provided to GSI field technicians; one is to be affixed to the vehicle when on site, the other is to be placed atop the spoil pile on all test pits. Flashing Lights: Ail vehicles stationary in the grading area shall use rotating or flashing amber beacon, or strobe lights, on the vehicle during all field testing. While operating a vehicle in the grading area, the emergency flasher on the vehicle shall be activated. In the event that the contractor's representative observes any of our personnel notfollowing the above, we request that it be brought to the attention of our office. Mr. Edward H. Hagey Appendix F Fite:e:\wp9\3200\3213a.pge Page 7 GeoSoils, Inc. Test Pits Location. Orientation and Clearance The technician is responsible for selecting test pit locations. A primary concern should be the technicians's safety. Efforts will be made to coordinat^ locations with the grading contractors authorized representative, and to select locations following or behind the established traffic pattern, preferably outside of current traffic. The contractors authorized representative (dump man, operator, supervisor, grade checker, etc.) should direct excavation of the pit and safety during the test period. Of paramount concern should be the soil technicians safety and obtaining enough tests to represent the fill. Test pits should be excavated so that the spoil pile is placed away form oncoming traffic, whenever possible. The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This necessitates the fill be maintained in a driveable condition. Alternatively, the contractor may wish to park a piece of equipment in front of the test holes, particularly in small fill areas or those with limited access. A zone of non-encroachment should be established for all test pits. No grading equipment should enter this zone during the testing procedure. The zone should extend approximately 50 feet outward from the center of the test pit. This zone is established for safety and to avoid excessive ground vibration which typically decreased test results. When taking slope tests the technician should park the vehicle directly above or below the test location. If this is not possible, a prominent flag should be placed at the top of the slope. The contractor's representative should effectively keep all equipment at a safe operation distance (e.g., 50 feet) away from the slope during this testing. The technician is directed to withdraw from the active portion of the fill as soon as possible following testing. The technician's vehicle should be parked at the perimeter of the fill in a highly visible location, well away from the equipment traffic pattern. The contractor should inform our personnel of all changes to haul roads, cut and fill areas or other factors that may affect site access and site safety. In the event that the technicians safety is jeopardized or compromised as a result of the contractors failure to comply with any of the above, the technician is required, by company policy, to immediately withdraw and notify his/her supervisor. The grading contractors representative will eventually be contacted in an effort to effect a solution. However, in the interim, no further testing will be performed until the situation is rectified. Any fill place can be considered unacceptable and subject to reprocessing, recompaction or removal. In the event that the soil technician does not comply with the above or other established safety guidelines, we request that the contractor brings this to his/her attention and notify this office. Effective communication and coordination between the contractors representative and the soils technician is strongly encouraged in order to implement the above safety plan. Mr. Edward H. Hagey Appendix F Rle:e:\wp9\320(A3213a.pge Page 8 GeoSoils, Inc. 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. 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 falls to provide safe access to trenches for compaction testing, our company policy requires that the soil technician withdraw and notify his/her supervisor. The contractors representative will eventually be contacted in an effort to effect a solution. All backfill not tested due to safety concerns or other reasons could be subject to reprocessing and/or removal. If GSI personnel become aware of anyone working beneath an unsafe trench wall or vertical excavation, we have a legal obligation to put the contractor and owner/developer on notice to immediately correctthe situation. If corrective steps are not taken, GSI then has an obligation to notify CAL-OSHA and/or the proper authorities. Mr. Edward H. Hagey Appendix F Re:e:\wp9\3200\3213a.pge * - • Page 9 GeoSoils, Inc. ain PLATE EG-6 LU Q O o: LU o LL Q < o O ZLU £i- £ z5 ul 22 Z H-^•^ ^HB fu0 ° Sx z o UJ ui 0- UJm 5 C Ul 2 H- 311 U> Ul u.o Ul H- DC>- 9 i- i- i23 < o0 3 3 < O > HiUl O Ul UJt-o PLATE EG-7 CO ^ -I o» B- o HJo -2 o£ ui s § § Ul o o» w Z Ul 2— D. Oee q zUl —I m 12so o " Z U, „llj D O Ul ***•» Ul 0-a u. inz _ ui DCUl Ul Ul IA o 1221m uj a =ui u & fe5 3 UJ MQ.in g ui £ H! r-103 3 X a Su aDC ^ a z ^ ^ Ul ECT SOce «a. 5: >• i-O U)a «Auj uz -1 7 uJE m ui • ui •a -J ui <m x-i «>I sU) I- m ui ' H 5S g " w _j U. 1-^ 1 < S iK X M Oa CA z _i O m- < Or> ^ x uiu> ? i- o »- r« • *iu oz PLATE EG-8 cco Qz uiuiz az UI ui CD QUIZzceui s H O oa:o UI oa UI — in a ou 3 oe. oui zo- 5 tu «/iin uisii iu a: LLo PLATE EG-9 UJu ce (Am=>in aUJinoa.xUl za aui(A at auiz ui tua UJm ini-z UIz UIoc 5auia: ui az DCa CO 3V) UJ Oz 5-03 inuiuuiz auiz UIa LL oUlz K !„•Ul IStOL 5 Ul °.ffl oa ui_i o i I2: w 5ui |2 uia z ui K 03 CJte <ui a. o oU Ulu.o Ul Ul „ 12z < O § «_ P m E < i < x ui i s 3I g S z a ofo < i00-1- PLATE EG-10 TRANSITION LOT DETAIL CUT LOT (MATERIAL TYPE TRANSITION) NATURAL GRADE COMPACTED RLL OVEREXCAVATE AND RECOMPACT ^^^V//\^A\V^\\\^ 3'MINIMUM* UNWEATHERED BEDROCK OR APPROVED MATERIAL TYPICAL BENCHING CUT-FILL LOT (DAYLIGHT TRANSITION) PAD GRADE NATURAL GRADE _^ <^^f^ . .kl*-«v»* • **• ^ "5- MINIMUM COMPACTED RLL *€•*a&. ^o^1,0^co,v^\><l\^o*OVEREXCAVATE *-^>^W AND RECOMPACT 3* MINIMUM* UNWEATHERED BEDROCK OR APPROVED MATERIAL TYPICAL BENCHING NOTE: * DEEPER OVEREXCAVATION MAY BE RECOMMENDED BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST IN STEEP CUT-FILL TRANSITION AREAS. PLATE EG-11 TEST PIT SAFETY DIAGRAM SIDE VIEW ( NOT TO SCALE ) TOP VIEW 100 FEET APPROXIMATE CENTER OF TEST PIT ( NOT TO SCALE ) PLATE EG—16