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HomeMy WebLinkAboutCT 04-05; Vista La Costa; Vista La Costa Soils Report; 2004-01-13t _ GEOTECHNICAL EVALUATION LOTS 20 AND 21, APNs 216-290-20, 216-290-21, AND 216-130-68 CITY OF CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA FOR DR. SHAHLA ABEDI C/O THE LIGHTFOOT PLANNING GROUP 702 CIVIC CENTER DRIVE OCEANSIDE, CALIFORNIA 92054 W.O. 4084-A-SC JANUARY 13, 2004 RECEIVED JAN. 16 7008 ENGINEERING DEPARTMENT Geotechnical • Coastal • Geologic • Environmental 5741 Palmer Way • Carlsbad, California 92010 • (760)438-3155 • FAX (760) 931-0915 January 13, 2004 W.O. 4084-A-SC Dr. Shahla Abedi c/o The Lightfoot Planning Group 702 Civic Center Drive Oceanside, California 92054 Attention: Ms. Alexis Pagnotta Subject: Preliminary Geotechnical Evaluation, Lots 20 and 21, APNs 216-290-20, 216-290-21, and 216-130-68, City of Carlsbad, San Diego County, California Dear Ms. Pagnotta: In accordance with your request, GeoSoils, Inc. (GSI), has performed a preliminary geotechnical evaluation of the subject site. The purpose of the study was to evaluate the onsite soils and geologic conditions and their effects on the proposed site development from a geotechnical viewpoint. EXECUTIVE SUMMARY Based on our review of the "Preliminary Design Plans" by O'Day Consultants (O'Day, 2003), (see Appendix A), field exploration, laboratory testing, 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 the design and construction of the project. The most significant elements of this study are summarized below: • Based on the preliminary design plans provided by O'Day, it appears that the proposed development will consist of the preparation of two relatively level building padsforthe construction of two, three-story multi-family structures, with underground parking and associated infrastructure (i.e., underground utilities, streets, etc.). It appears that sewage disposal will be tied into the municipal system. The need for import soils is unknown at this time. All deleterious debris and vegetation should be removed from the site and properly disposed of, should settlement-sensitive improvements be proposed within their influence. Removals of compressible undocumented artificial fill, coliuvial soils, and weathered Quaternary-age terrace deposits will be necessary prior to fill placement. Depths of removals are outlined in the "Conclusions and Recommendations" section of this report. In general, removals will be on the order of ±10 to ±20 feet across a majority of the site. However, localized deeper removals cannot be precluded. To provide for uniform foundation support, overexcavation of the terrace deposits to a depth of 4 feet below finish grade is recommended. If proposed footings or isolated pad footings are deeper than 24 inches below finish pad grade elevation, additional overexcavation will be necessary to provide a minimum 24 inches of compacted fill beneath the footing. Maximum to minimum fill thickness below the foundation elements of the structures should not exceed a ratio of 3:1 (maximum:minimum). Based on site conditions and laboratory testing, the existing ± 15-foot high fill slope, along the northern margin of the site, is grossly and surficially unstable in its present condition. It will be necessary to reconstruct this existing perimeter fill slope to comply with current industry standards. Avoidance of existing utilities, etc., will be necessary. The expansion potential of tested onsite soils is medium (Expansion Index [E.I.] 51 to 90). However, review of AEL (1989) indicates that highly expansive soils (Expansion Index [E.I.] 91 to 130) are present onsite. Therefore, the potential for highly expansive soils exposed at finish grade cannot be precluded. Conventional or Post-tensioned foundation systems may be utilized for medium expansive soil conditions. Post-tensioned foundation systems are specifically recommended if highly expansive soils are exposed near finish grade. Should expansive soils exist near finish grade at the conclusion of grading, there will be the potential for distress to flatwork, etc., owing to the nature of expansive soils. This will need to be disclosed to all owners. At the present time, laboratory test results concerning the corrosion potential and sulfate exposure of site soils were not available. An addendum report, presenting these laboratory test results, will be issued when the data is made available. Groundwater was not observed during the field investigation and is not expected to be a major factor in development of the site. However, due to the nature of the site materials, seepage and/or perched groundwater conditions may develop throughout the site along boundaries of contrasting permeabilities (i.e., fill/terrace deposit contacts), and should be anticipated. Our evaluation indicates that the site has a very low potential for liquefaction. Therefore, no recommendations for mitigation are deemed necessary. Dr. Shahla Abedi W.O. 4084-A-SC File:e:\wp9\4000\4084a.pge Page Two GeoSoilSj Inc. The seismic acceleration values and design parameters provided herein should be considered during the design of the proposed development. • Our evaluation indicates there are no known active faults crossing the site. • Adverse geologic features that would preclude project feasibility were not encountered. • The recommendations presented in this report should be incorporated into the design and construction considerations of the project. 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 any of the undersigned. Respectfully submitted, GeoSoils, Inc. Ryan Boehmer Staff Geologist Reviewed by: No. 1340 Certified Engineering Geologist John P. Franklin Engineering Geologist^ RB/JPF/BBS/jh/jk Distribution: (6) Addressee 340 Reviewed by: /v^-^-—;0x D Qh . . . J>CM-\eBen Shahrvmi Civil Engineer, RCE 2296 Dr. Shahla Abedi File:e:\wp9\4000\4084a.pge GeoSoils, Inc. W.O. 4084-A-SC Page Three TABLE OF CONTENTS SCOPE OF SERVICES 1 SITE CONDITIONS/PROPOSED DEVELOPMENT 1 SITE EXPLORATION 3 REGIONAL GEOLOGY 3 SITE GEOLOGIC UNITS 3 Artificial Fill - Undocumented (Map Symbol - Afu) 4 Quaternary Colluvium (Not Mapped) 4 Quaternary-age Terrace Deposits (Map Symbol - Qt) 4 FAULTING AND REGIONAL SEISMICITY 5 Regional Faults 5 Seismicity 5 Seismic Shaking Parameters 7 Seismic Hazards 8 GROUNDWATER 8 LIQUEFACTION POTENTIAL 9 LABORATORY TESTING 10 General 10 Classification 10 Moisture-Density Relations 10 Laboratory Standard 10 Expansion Potential 10 Direct Shear Test 11 Atterberg Limits 11 Consolidation Testing 11 Corrosion/Sulfate Testing 12 SLOPE STABILITY 12 Gross Stability Analysis 12 Surficial Slope Stability 12 CONCLUSIONS 13 General 13 EARTHWORK CONSTRUCTION RECOMMENDATIONS 15 General 15 Site Preparation 15 Removals (Unsuitable Surficial Materials) 15 GeoSoils, Inc. Fill Placement 16 Slope Considerations and Slope Design 16 Transitions/Overexcavation 16 Temporary Cut Slopes 17 SUBDRAINS 17 RECOMMENDATIONS - FOUNDATIONS 17 Preliminary Foundation Design 17 Bearing Value 18 Lateral Pressure 18 Foundation Settlement 18 Footing Setbacks 18 Construction 19 Medium Expansion Potential (E.I. 51 to 90) 19 POST-TENSIONED SLAB SYSTEMS 20 Post-Tensioning Institute Method 21 CORROSION 22 UTILITIES 23 WALL DESIGN PARAMETERS CONSIDERING EXPANSIVE SOILS 23 Conventional Retaining Walls 23 Restrained Walls 23 Cantilevered Walls 23 Retaining Wall Backfill and Drainage 24 Wall/Retaining Wall Footing Transitions 28 TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS AND EXPANSIVE SOILS 28 Expansive Soils and Slope Creep 28 Top of Slope Walls/Fences 29 EXPANSIVE SOILS, DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS 30 DEVELOPMENT CRITERIA 31 Slope Deformation 31 Slope Maintenance and Planting 32 Drainage 32 Erosion Control 33 Landscape Maintenance 33 Gutters and Downspouts 34 Subsurface and Surface Water 34 Site Improvements 34 Tile Flooring 34 Dr. Shahla Abedi Table of Contents File:e:\wp9\4000\4084a.pge Page ii GeoSoils, Inc. Additional Grading 35 Footing Trench Excavation 35 Trenching 35 Utility Trench Backfill 35 SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING 36 OTHER DESIGN PROFESSIONALS/CONSULTANTS 36 PLAN REVIEW 37 LIMITATIONS 37 FIGURES: Figure 1 - Site Location Map 2 Figure 2 -California Fault Map 6 Detail 1 - Typical Retaining Wall Backfill and Drainage Detail 25 Detail 2 - Retaining Wall Backfill and Subdrain Detail Geotextile Drain 26 Detail 3 - Retaining Wall and Subdrain Detail Clean Sand Backfill 27 ATTACHMENTS: Plate 1 - Geotechnical Map Rear of Text Appendix A - References Rear of Text Appendix B - Boring Logs 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 Dr. Shahla Abedi Table of Contents File:e:\wp9\4000\4084a.pge Page ill GeoSoils, Inc. PRELIMINARY GEOTECHNICAL EVALUATION LOTS 20 AND 21, APNs, 216-290-20, 216-290-21, AND 216-130-68, CITY OF CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA SCOPE OF SERVICES The scope of our services has included the following: 1. Review of the available geologic literature for the site (see Appendix A). 2. Geologic site reconnaissance, subsurface exploration with four exploratory borings (see Appendix B), sampling, and mapping. 3. General areal seismicity evaluation (see Appendix C). 4. Appropriate laboratory testing of representative soil samples (see Appendix D). 5. Slope stability analysis of the existing fill slope (see Appendix E). 6. Engineering and geologic analysis of data collected. 7. Preparation of this report. SITE CONDITIONS/PROPOSED DEVELOPMENT The subject site is composed of two previously graded, vacant, relatively level building pads located on the north side of Gibraltar Street in the City of Carlsbad, California (see Figure 1, Site Location Map). The property is bounded to the north by a golf course, residential developments to the east and west, and Gibraltar Street to the south. A buried, north - south trending storm drain line was observed to transect the property on the eastern margin. Additionally, a buried north - south trending sewer line was observed to transect the property along the western margin. A slope with approximate heights of ±15 to ±25 feet, and approximate gradients of 1.7:1 (horizontal:vertical), or flatter, was observed descending from the building pads to the golf course. The western building pad is approximately 6 feet higher in elevation than the eastern building pad. Vegetation consists of weeds and grasses with sparse trees located on the slopes that descend to the golf course. Elevations across the site range from approximately 42 feet above Mean Sea Level (MSL) along the northeastern margin of the property to 61 feet above MSL along the southwestern margin of the property. Therefore, maximum relief across the site is on the order of 19 feet. Based on the preliminary site plan provided by O'Day (2003), it appears that proposed development will consist of preparing the property for the construction of two, three-story multi-family, residential structures, utilizing wood frames and slabs-on-grade, with underground parking and associated improvements. Building loads are assumed to be GeoSoils, Inc. n. VIFIU096 Sourte Data: USGS --; 'T"'""""1^ -HU SITE LOCATION MAP Scale typical for this type of relatively light construction (three floor loads, as defined in the UBC). It is anticipated that sewage disposal will be tied into the municipal system. SITE EXPLORATION Surface observations and subsurface explorations were performed on December 8,2003, by a representative of this office. A survey of line and grade for the subject lot was not conducted by this firm at the time of our site reconnaissance. Near surface soil conditions were explored with four exploratory borings within the site to evaluate soil and geologic conditions. The approximate locations of each boring are shown on the attached Geotechnical Map (see Plate 1). Boring Logs are presented in Appendix B. REGIONAL GEOLOGY The subject property is located within a prominent natural geomorphic province in southwestern California known as the Peninsular Ranges. It is characterized by steep, elongated mountain ranges and valleys that trend northwesterly. The mountain ranges are underlain by basement rocks consisting of pre-Cretaceous metasedimentary rocks, Jurassic metavolcanic rocks, and Cretaceous plutonic rocks of the southern California batholith. In the San Diego County region, deposition occurred during the Cretaceous Period 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. SITE GEOLOGIC UNITS The site geologic units encountered during our subsurface investigation and site reconnaissance differed from AEL's findings during their preliminary investigation of the site. According to AEL (1989), the site is mantled by alluvial soils which are directly underlain by terrace deposits. However, our investigation indicated that the site is mantled by undocumented artificial fill which is directly underlain by Quaternary-age terrace deposits. Discontinuous, Quaternary-age colluvial soils were observed to also directly underlie the undocumented artificial fill and overlie the Quaternary-age terrace deposits in Borings B-3 and B-4. The earth materials, observed during GSI's investigation, are Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 3 GeoSoils, Inc. generally described below from the youngest to the oldest. The distribution of these materials is shown on Plate 1. Artificial Fill - Undocumented (Map Symbol - Afu) Undocumented artificial fill was observed to mantle the site in all of the boring excavations. The encountered undocumented artificial fill consists of yellow brown to brown to olive brown to olive gray to dark brown sandy clays, dark brown to olive brown to dark gray brown to medium brown, highly plastic clays with varying amounts of sand, and yellow brown silty sands that were observed to be dry and dessicated near the surface, becoming moist with depth. The density of these undocumented fill materials was observed to be soft near the surface becoming stiff/medium dense to very stiff with depth, and was non-uniform. A majority of these materials are not in accordance with current industry standards and have locally been placed upon unsuitable bearing soils. Therefore, these fill soils are considered potentially compressible in their existing state and will require removal and recompaction if fill or settlement-sensitive improvements are proposed within their influence. Further, owing to their non-uniform nature, they may pose slope stability problems on existing slopes. Quaternary Colluvium (Not Mapped) Quaternary-age colluvial soils were observed to directly underlie the artificial fill in Borings B-3 and B-4, and consist of dark brown to dark gray brown sandy clay and dark gray brown clays that were observed to be moist and locally soft to hard. The thickness of these colluvial soils is on the order of ±21/2 to ±5 feet. These materials are considered to be unsuitable for the support of engineered fill and/or settlement-sensitive improvements due to their porous nature, and therefore are potentially compressible in their existing state. Mitigation in the form of removal and recompaction will be necessary if engineered fill and/or settlement-sensitive structures are proposed within their influence. Quaternary-age Terrace Deposits (Map Symbol - Qt) Quaternary-age terrace deposits were observed to underlie the undocumented fill and colluvial soils, and consist of interbedded clayey sands/sandy clays to clays to poorly graded sands. These deposits are generally olive gray to red brown to yellow brown to gray to dark gray brown to olive brown and dry to moist. The relative density of these deposits varied from medium dense to very dense/very stiff to hard. These materials are considered to be suitable for the support of engineered fill and/or settlement-sensitive improvements. However, the upper ±1 foot of these sediments are generally weathered and considered unsuitable for structural support in its present condition, and should be removed and recompacted or processed in place. Bedding structure was observed to be generally flat lying to sub-horizontal. Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 4 GeoSoils, Inc. FAULTING AND REGIONAL SEISMICITY Regional Faults 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 Figure 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 significant affect on the site, should they experience activity, are listed in the following table (modified from Blake, 2000a): ABBREVIATED FAULT NAME Rose Canyon Newport-lnglewood (Offshore) Coronado Bank Elsinore-Julian Elsinore-Temecula Elsinore-Glen Ivy Earthquake Valley Palos Verdes San Jacinto-Anza San Jacinto-San Jacinto Valley San Jacinto-Coyote Creek APPROXIMATE DISTANCE MILES (KM) 6.6(10.7) 11.7(18.9) 21.5(34.6) 24.2 (39.0) 24.3 (39.1) 39.0 (62.7) 39.1 (62.9) 42.3 (68.1) 47.0 (75.7) 49.0 (78.9) 49.9 (80.3) Seismicity The acceleration-attenuation relations of Bozorgnia, Campbell, and Niazi (1999) and Campbell and Bozorgnia (1997 Revised) have been incorporated into EQFAULT (Blake, 2000a). EQFAULT is a computer program developed by Thomas F. Blake (2000a), which performs deterministic seismic hazard analyses using digitized California faults as earthquake sources. Dr. Shahla Abedi APNs 216-290-20, 216-290-21, 216-130-68 File:e:\wp9\4000\4084a.pge W.O. 4084-A-SC January 13, 2004 Pages GeoSoils, Inc. CALIFORNIA FAULT MAP ABEDI 1100 1000 -- 900-- 800-- -400 -300 -200 -100 0 100 200 300 400 500 600 W.O. 4084-A-SC Figure 2 GeoSoils, Inc. 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 one or more user-selected acceleration-attenuation relations that are contained in EQFAULT. Based on the EQFAULT program, peak horizontal ground accelerations from an upper bound event at the site may be on the order of 0.47g to 0.56g. The computer printouts of portions of the EQFAULT program are included within Appendix C. Historical site seismicity was evaluated with the acceleration-attenuation relations of Campbell and Bozorgnia (1997 Revised) and the computer program EQSEARCH (Blake, 2000b). This program performs a search of the historical earthquake records for magnitude 5.0 to 9.0 seismic events within a 100-mile radius, between the years 1800 to June, 2003. Based on the selected acceleration-attenuation relationship, a peak horizontal ground acceleration is estimated, which may have effected the site during the specific event listed. Based on the available data and the attenuation relationship used, the estimated maximum (peak) site acceleration during the period 1800 to June, 2003, was 0.38g. Site specific probability of exceeding various peak horizontal ground accelerations and a seismic recurrence curve are also estimated/generated from the historical data. Computer printouts of the EQSEARCH program are presented in Appendix C. A probabilistic seismic hazards analyses was performed using FRISKSP (Blake, 2000c), which models earthquake sources as three-dimensional planes and evaluates the site specific probabilities of exceedance for given peak acceleration levels or pseudo-relative velocity levels. Based on a review of this data, and considering the relative seismic activity of the southern California region, a peak horizontal ground acceleration of 0.25g 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: 1997 UBC CHAPTER 16 TABLE NO. Seismic Zone (per Figure 16-2*) Seismic Zone Factor (per Table 16-1*) Soil Profile Type (per Table 16-J*) SEISMIC PARAMETERS 4 0.40 SD Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 7 GeoSoils, Inc. 1 997 UBC CHAPTER 1 6 TABLE NO. Seismic Coefficient Ca (per Table 16-Q*) Seismic Coefficient Cv (per Table 1 6-R*) Near Source Factor Na (per Table 1 6-S*) Near Source Factor Nv (per Table 1 6-T*) Distance to Seismic Source Seismic Source Type (per Table 16-U*) Upper Bound Earthquake (Rose Canyon fault) SEISMIC PARAMETERS 0.44Na 0.64NV 1.0 1.1 6.6 mi (10.7 km) B MW6.9 * Figure and Table references from Chapter 16 of the UBC (ICBO, 1997) Seismic Hazards The following list includes other seismic related hazards that have been considered during our evaluation of the site. With the exception of the very low potential for tsunami, 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 • Seiche It is important to keep in perspective that in the event of a maximum probable or credible earthquake occurring on any of the nearby major faults, strong ground shaking would occur in the subject site's general area. Potential damage to any structure(s) would likely be greatest from the vibrations and impelling force caused by the inertia of a structure's mass than from those induced by the hazards considered above. This potential would be no greater than that for other existing structures and improvements in the immediate vicinity. There is no economic mitigation for tsunami potential that GSI is aware of, considering the site's location and surroundings. GROUNDWATER Subsurface water was not encountered within the property during field work performed in preparation of this report. Subsurface water is not anticipated to adversely affect site development, provided that the recommendations contained in this report are incorporated into final design and construction. These observations reflect site conditions at the time of our investigation and do not preclude future changes in local groundwater conditions from Dr. Shahla Abed! APNs 216-290-20, 216-290-21, 216-130-68 File:e:\wp9\4000\4084a.pge W.O. 4084-A-SC January 13, 2004 Page8 GeoSoils, Inc. excessive irrigation, precipitation, or that were not obvious at the time of our investigation. The regional groundwater table is anticipated to be near MSL Perched groundwater conditions along fill/terrace deposit 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. LIQUEFACTION POTENTIAL Seismically-induced liquefaction is a phenomenon in which cyclic stresses, produced by earthquake-induced ground motion, create excess pore pressures in soils. The soils may thereby acquire a high degree of mobility, and lead to lateral movement, sliding, sand boils, consolidation and settlement of loose sediments, and other damaging deformations. This phenomenon occurs only below the water table; but after liquefaction has developed, it can propagate upward into overlying, non-saturated soil as excess pore water dissipates. Typically, liquefaction has a relatively low potential at depths greater than 45 feet and is virtually unknown below a depth of 60 feet. Liquefaction susceptibility is related to numerous factors and the following conditions should be concurrently present for liquefaction to occur: 1) sediments must be relatively young in age and not have developed a large amount of cementation; 2) sediments generally consist of medium to fine grained relatively cohesionless sands; 3) the sediments must have low relative density; 4) free groundwater must be present in the sediment; and 5) the site must experience a seismic event of a sufficient duration and magnitude, to induce straining of soil particles. The condition of liquefaction has two principal effects. One is the consolidation of loose sediments with resultant settlement of the ground surface. The other effect is lateral sliding. Significant permanent lateral movement generally occurs only when there is significant differential loading, such as fill or natural ground slopes within susceptible materials. No such loading conditions exist on the site since the site is underlain by dense/hard terrace deposits. In the site area, we found there is a potential for seismic activity and a groundwater table deeper than 50 feet below the ground surface. However, the terrace deposits were generally fine grained, and become very dense/hard with depth. Since at least two or three of these five required concurrent conditions discussed above do not have the potential to affect the site, and considering the recommended remedial removals, our evaluation indicates that the potential for liquefaction and associated adverse effects within the site is very 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 Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21,216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 9 GeoSoils, Inc. soils. Therefore, it is our opinion that the liquefaction potential does not constitute a significant risk to site development. LABORATORY TESTING General Laboratory tests were performed on representative samples of the onsite earth materials in order to evaluate their physical characteristics. The test procedures used and results obtained are presented below. Classification Soils were classified visually according to the Unified Soils Classification System. The soil classifications are shown on the Boring Logs in Appendix B. Moisture-Density Relations The field moisture contents and dry unit weights were determined for selected undisturbed samples in the laboratory. The dry unit weight was determined in pounds per cubic foot (pcf), and the field moisture content was determined as a percentage of the dry weight. The results of these tests are shown on the Boring Logs in Appendix B. Laboratory Standard The maximum dry density and optimum moisture content was determined for the major soil type encountered in the exploratory borings. The laboratory standard used was ASTM D-1557. The moisture-density relationship obtained for this soil is shown below: SOIL TYPE Gray Brown, CLAY w/SAND Dark Gray Brown, CLAY w/SAND BORING AND DEPTH (FT) B-1 @5-10 B-3@10-12 MAXIMUM DRY DENSITY (PCF) 121.0 121.0 OPTIMUM MOISTURE CONTENT (%) 13.0 13.0 Expansion Potential Expansion testing was performed on a representative samples of site soil in accordance with UBC Standard 18-2. The results of expansion testing are presented in the following table. Dr. Shahla Abedi APNs 216-290-20, 216-290-21, 216-130-68 File:e:\wp9\4000\4084a.pge W.O. 4084-A-SC January 13,2004 Page 10 GeoSoils, Inc. BORING AND DEPTH (FT) B-1 @ 0-5 B-1 @5-10 EXPANSION INDEX 71 63 EXPANSION POTENTIAL Medium Medium Direct Shear Test Shear testing was performed on a representative, "remolded" sample of site soil in general accordance with ASTM Test Method D-3080 in a Direct Shear Machine of the strain control type. The shear test results are presented as follows and are provided as Plate D-1 in Appendix D: BORING AND DEPTH (FT) B-3@ 10-12 PRIMARY COHESION (PSF) 468 FRICTION ANGLE (DEGREES) 22 RESIDUAL COHESION (PSF) 475 FRICTION ANGLE (DEGREES) 22 Atterberq Limits Testing was performed on a selected representative fine grained soil sample to evaluate the liquid limit, plastic limit and plasticity index in general accordance with ASTM D4318-64. The test result is presented in the following table and as Plate D-2 in Appendix D. BORING AND DEPTH (FT) B-1 @5-10 LIQUID LIMIT 50 PLASTIC LIMIT 16 PLASTICITY INDEX 34 Consolidation Testing Consolidation testing was performed on a relatively undisturbed soil sample in general accordance with ASTM Test Method D-2435-90. The consolidation test result is presented as Plate D-3 in Appendix D. Dr. Shahla Abedi APNs 216-290-20, 216-290-21, 216-130-68 File:e:\wp9\4000\4084a.pge W.O. 4084-A-SC January 13, 2004 Page 11 GeoSoils, Inc. Corrosion/Sulfate Testing At the present time, laboratory test results concerning the corrosion potential and sulfate exposure of site soils were not available. An addendum report, presenting these laboratory test results, will be issued when the data is made available. 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. A representative geologic cross-section was prepared for analysis, utilizing field and laboratory data and the 40-scale design study, depicting the existing ± 15-foot high fill slope along the site's northwestern property margin, as indicated on Cross-Section A-A'. The results of the analyses are included in Appendix E. Gross Stability Analysis A calculated factor-of-safety less than 1.5 from a static viewpoint and greater than 1.1 from a seismic viewpoint has been obtained for the existing fill slope. The results of the analyses are included in Appendix E. Surficial Slope Stability The surficial stability of the existing slope has been analyzed. Our evaluation indicates a surficial safety factor of less than 1.1, from a static viewpoint, for the existing fill slope. Laboratory testing indicates that a majority of the existing fill soils from which the slope was previously constructed, are non-uniform and not in accordance with current industry standards of 90 percent of laboratory standard (in-situ density determinations are presented on the Boring Logs located in Appendix B). In Borings B-3 and B-4, these fill soils were observed to be placed upon colluvial soils. The slope was also constructed at gradient steeper than 2:1 (h:v). According to current industry standards, fill slopes shall not be constructed at a gradient steeper than 2:1 (h:v). Additionally, surficial slope instability in the form of "tension cracking" was observed approximately 2 to 3 feet south of the top of the slope along the northwestern property margin. The "tension cracking" is most likely attributed to expansion and contraction of the medium to highly expansive existing, fill soils and the force of gravity acting upon these surficial soils resulting in downslope "creep." Based on the factors listed above and the results from our slope stability analysis, GSI recommends the complete reconstruction of existing fill slopes in order to mitigate slope instability, and comply with current industry standards. Recommendations for slope construction are provided in the "Earthwork Construction Recommendations" and the "General Earthwork and Grading Guidelines" (see Appendix F) sections of this report. Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21,216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 12 GeoSoils, Inc. CONCLUSIONS General Based on our field exploration, laboratory testing, and geotechnical engineering analysis, it is our opinion that the site appears suitable for the proposed development from a geotechnical engineering and geologic viewpoint, provided that the recommendations presented in the following sections are incorporated into the design and construction phases of site development. The primary geotechnical concerns with respect to the proposed development are: • Depth to competent bearing soils and remedial removals/presence of existing utilities, etc. • Overexcavation of basement pads. • Potential for perched groundwater after development • Expansion and corrosion potential of site soils. • Slope stability of existing fill slopes. • Regional seismic activity. 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. Existing undocumented artificial fill on the order of ± 10 to ±20 feet thick, colluvial soils on the order of ±5 feet thick, and the upper ±1 foot of the weathered terrace deposits are considered unsuitable for the support of settlement-sensitive improvements and/or engineered fill in their present condition, based on current industry standards. These materials are potentially compressible in their present condition, and may be subject to differential settlement. Mitigation in the form of removal and recompaction will be necessary. Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 13 GeoSoils, Inc. 4. To provide for uniform foundation support, overexcavation of the terrace deposits to a depth of 4 feet below finish grade is recommended. If proposed footings or isolated pad footings are deeper than 24 inches below finish pad grade elevation, additional overexcavation will be necessary to provide a minimum 24 inches of compacted fill beneath the footing. 5. In general and based upon the available data to date, groundwater is not expected to be a major factor in development of the site assuming shallow excavations. However, perched groundwater conditions along fill/terrace deposit 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. In addition, subdrainage systems for the control of localized groundwater seepage should be anticipated. The proposed locations of such drains can be delineated at the grading plan review stage of planning. 6. Due to the nature of some of the onsite materials, some caving and sloughing may be anticipated to be a factor in subsurface excavations and trenching. Therefore, current local and state/federal safety ordinances for subsurface excavations should be enforced. Temporary cut slopes should be further evaluated during grading and/or the grading plan review stage. 7. General Earthwork and Grading Guidelines are provided at the end of this report as Appendix F. Specific recommendations are provided below. 8. Our laboratory test results and experience on nearby sites related to expansion potential indicate that soils with medium expansion indices (locally) underlie the site. Review of AEL (1989) indicates that medium to highly expansive soils are present onsite. This should be considered during project design. Foundation design and construction recommendations are provided herein for medium and high expansion potential classifications. 9. Our slope stability analysis, laboratory testing of the existing undocumented artificial fill, and the observed site conditions (i.e., fill slope steeperthan 2:1 [h:v] and tension cracking [slope creep] along the top of the northwestern slope) indicate that the existing fill slopes are grossly and surficially unstable and their present condition and will require removal and recompaction of the existing undocumented fill and slope reconstruction that is in accordance with current industry standards. 10. The seismicity-acceleration values provided in the "Faulting and Regional Seismicity" section of this report should be considered during the design of the proposed development. Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21,216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 14 GeoSoils, Inc. EARTHWORK CONSTRUCTION RECOMMENDATIONS General All grading should conform to the guidelines presented in Appendix Chapter A33 of the UBC, the requirements of the City, and the Grading Guidelines presented in Appendix F, except where specifically superceded in the text of this report. Prior to grading, a GSI representative should be present at the preconstruction meeting to provide additional grading guidelines, if needed, and review the earthwork schedule. During earthwork construction, all site preparation and the general grading procedures of the contractor should be observed and the fill selectively tested by a representative(s) of GSI. If unusual or unexpected conditions are exposed in the field, they should be reviewed by this office and, if warranted, modified and/or additional recommendations will be offered. All applicable requirements of local and national construction and general industry safety orders, the Occupational Safety and Health Act (OSHA), and the Construction Safety Act should be met. Site Preparation All deleterious materials should be removed from the site prior to the start of construction. Removals (Unsuitable Surficial Materials) Laboratory testing of the existing fill soils encountered within the exploratory borings are generally not in conformance with the current industry standard of 90 percent relative compaction. Additionally, these materials have locally been placed upon unsuitable bearing soils (i.e., colluvium). Therefore, these existing fill soils, along with the colluvial soils, and weathered terrace deposits, should be removed and recompacted in areas proposed for settlement-sensitive structures or areas to receive engineered fill. At this time, removal depths on the order of ±10 to ±20 feet (including the upper ±1 foot of the weathered terrace deposits) below existing grade should be anticipated throughout a majority of the site; however, locally deeper removals cannot be precluded and should be anticipated. Removals should be completed below a 1:1 projection down and away from the edge of any settlement-sensitive structure and/or limit of proposed fill. Removal excavations, adjacent to existing utilities that cross the site, should not be completed below 5 feet from the top of pipe and subsequently be completed above a 1:1 (h:v) projection down and away from a point located 5 feet from either side of the utility. Once removals are completed, the exposed bottom should be scarified in two perpendicular directions, moisture conditioned to at least optimum moisture content, and recompacted to 90 percent relative compaction. Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 15 GeoSoils, Inc. Fill Placement Subsequent to ground preparation, onsite soils may be placed in thin (±6- to 8-inch) lifts, cleaned of vegetation and debris, brought to at least optimum moisture content (130 percent of the soil's optimum moisture content if fill soils are highly expansive), and compacted to achieve a minimum relative compaction of 90 percent. If fill soil importation is planned, a sample of the soil import should be evaluated by this office prior to importing, in order to assure compatibility with the onsite soils and the recommendations presented in this report. At least three business days of lead time should be allowed by builders or contractors for proposed import submittals. This lead time will allow for particle size analysis, specific gravity, relative compaction, expansion testing, and blended import/native characteristics as deemed necessary. Import soils for a fill cap should be very low to medium expansive (E.I. less than 91). The use of subdrainsatthe bottom of the fill cap may be necessary, and subsequently recommended based on compatibility with onsite soils and other considerations. Slope Considerations and Slope Design Our slope stability analysis, laboratory testing of the existing undocumented artificial fill, and the observed site conditions (i.e., fill slopes steeperthan 2:1 [h:v] and apparent tension cracking [slope creep] along the top of the northwestern slope) indicate that the existing fill slopes are generally grossly and surficially unstable in their present condition and will require removal and recompaction of the existing undocumented fill and subsequent reconstruction that is in accordance with current industry standards. Based on our experience with similar projects, the reconstructed fill slopes, using onsite materials to the heights proposed, should be grossly and surficially stable provided the recommendations contained herein are implemented during site development. All slopes should be designed and constructed in accordance with the minimum requirements of the City, and the recommendations in the General Earthwork and Grading Guidelines section of this report (see Appendix F), and the following: Fill slopes should be designed and constructed at a 2:1 (h:v) gradient, or flatter, and should not exceed about 30 feet in height. Fill slopes should be properly built and compacted to a minimum relative compaction of 90 percent throughout, including the slope surfaces. Guidelines for slope construction are presented in Appendix F. Transitions/Overexcavation In order to provide for the uniform support of the proposed structures, a minimum 4-foot thick fill blanket is recommended for lots containing earth material transitions (i.e., fill juxtaposed to terrace deposits). Any cut portion of a transition lot or lots with planned fills less than 4 feet should be overexcavated a minimum 4 feet below finish pad grade in order to provide for a minimum 4-foot compacted fill blanket. If proposed footings or isolated pad Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21,216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 16 GeoSoils, Inc. footings are deeper than 24 inches below finish pad grade elevation, additional overexcavation will be necessary to provide a minimum 24 inches of compacted fill beneath the footing. Maximum to minimum fill thickness below the foundation elements of the structures should not exceed a ratio of 3:1 (maximum:minimum). Temporary Cut Slopes Unsupported excavations should be constructed in accordance with criteria established in Article 6 of the State of California, Construction Safety Orders (CAL/OSHA) for Type "B" soils. On a preliminary basis, temporary cut slopes for removals may be inclined at gradient of 1:1 (h:v). Heavy equipment and/or stockpile should not be stored within 5 feet of any temporary cut slope. Additionally, heavy equipment should not be operated within 5 feet from the top of any temporary cut slope. Temporary cut slopes should be further evaluated during site grading. The possibility of inclining temporary cut slopes to a flatter gradient may be recommended if adverse soil conditions are observed. If the required gradient of any temporary cut slope conflicts with property boundaries, shoring may be necessary. SUBDRAINS Subdrainage systems for the control of localized perched water seepage may be necessary and will be evaluated during site grading, based on the presence of buried swales, thickness of fill cover, and flowline gradients into suitable outlets.. RECOMMENDATIONS - FOUNDATIONS Preliminary Foundation Design In the event that the information concerning the proposed development plans is not correct, or any changes in the design, location, or loading conditions of the proposed structures are made, the conclusions and recommendations contained in this report are for the subject site only, and shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or approved in writing by this office. The information and recommendations presented in this section are considered minimums and are not meant to supercede design(s) by the project structural engineer or civil engineer specializing in structural design. They are considered preliminary recommendations for proposed construction, in consideration of our field investigation, laboratory testing, and engineering analysis. Upon request, GSI could provide additional consultation regarding soil parameters, as related to foundation design. Our review, field work, and recent laboratory testing indicates that onsite soils have a medium expansion potential (E.I. 51 to 90). However, review of AEL (1989) indicates that Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 17 GeoSoils, Inc. highly expansive soils (E.I. 91 to 130) are also present onsite. Preliminary recommendations for foundation design and construction are presented below. Final foundation recommendations will be provided at the conclusion of grading, 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 design of continuous footings 12 inches wide and 12 inches deep, and for design of isolated pad footings 24 inches square and 24 inches deep, founded entirely into compacted fill and connected by grade beam or tie beam in at least one direction. This value may be increased by 20 percent for each additional 12 inches in depth to a maximum value of 2,500 psf. The above values may be increased by one-third when considering short duration seismic or wind loads. No increase in bearing for footing width is recommended. Lateral Pressure 1. For lateral sliding resistance, a 0.30 coefficient of friction may be utilized for a concrete to soil contact when multiplied by the dead load. 2. Passive earth pressure may be computed as an equivalent fluid having a density of 250 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. Foundation Settlement Foundation systems should be designed to accommodate a differential settlement of at least %-inch in a 40-foot span. 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 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 fo the wall. Alternatively, walls may be Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 18 GeoSoilSj Inc. designed to accommodate structural loads from buildings or appurtenances as described in the "Wall Design Parameters Considering Expansive Soils" section of this report. Alternatively, walls may be designed to accommodate structural loads from buildings or appurtenances as described in the "Wall Design Parameters Considering Expansive Soils" section of this report. Construction The following foundation construction recommendations are presented as a minimum criteria from a soils engineering standpoint. The onsite soil expansion potential is generally medium (E.I. 51 to 90). However, according to AEL (1989) highly expansive soils (E.I. 91 to 130) are also present onsite. Conventional foundations may be utilized if medium expansive soils are exposed at finish grade. However, post-tensioned foundations will be specifically recommended if highly expansive soils are present at finish grade. Preliminary recommendations for conventional and post-tensioned foundation systems are provided herein. Recommendations by the project's 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 finish grade soils encountered at the conclusion of grading. Medium Expansion Potential (E.I. 51 to 90) 1. For site soils with high plastic range (plasticity index >15), the design on conventional slab-on-ground foundations should follow the requirements of Section 1815 of the UBC (ICBO, 1997). Preliminary geotechnical parameters required for structural design are presented below: Climatic rating (Cw) = 15 Weighted plasticity index = 34 Over consolidation coefficient C0) = 1.0 Slope soil coefficient (Cs) = 1.0 2. Conventional continuous footings should be founded at a minimum depth of 24 inches below the lowest adjacent ground surface for a three-story floor load into compacted fill. Footings for three-story floor loads should have a minimum width of 24 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. Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 19 GeoSoils, Inc. 3. A grade beam, reinforced as above, and at least 18 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. 4. Concrete slabs should be underlain by a vapor barrier consisting of a minimum of 10-mil, polyvinyl-chloride membrane with all laps sealed. The vapor barrier should be placed mid-depth within 4 inches of washed sand to aid in uniform curing of the concrete and to prevent puncture of the vapor barrier. 5. Concrete slabs, including garage areas, should be a minimum of 5 inches thick, and reinforced with No. 4 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. 6. 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. 7. Presaturation of slab areas is recommended for these soil conditions. The moisture content of each slab area should be at least 120 percent of the soil's optimum moisture content and be verified by the soil engineer to a depth of 24 inches below the 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. Post-tension foundation recommendations are provided herein. 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 Post-tension foundations are specifically recommended for lots where highly expansive soils are exposed at finish grade. The recommendations presented below should be Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 20 GeoSoils, Inc. 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. Perimeter cut-off walls should be a minimum of 24 inches deep for expansive soils. The cut off walls may be integrated into the slab design or independent of the slab. The concrete slab should be a minimum of 5 inches thick. Slab underlayment should consist of 4 inches of washed sand with a vapor barrier consisting of 10-mil polyvinyl chloride or equivalent placed mid-depth within the sand. Specific soil presaturation is required if medium to highly expansive soils are exposed at finish grade. The moisture content of the slab subgrade soils should be equal to, or greater than, 130 percent of the soil's optimum moisture content to a depth of 30 inches below grade, for highly expansive soils (120 percent of the soil's optimum moisture content to a depth of 24 inches for medium expansive soils). Post-Tensioning Institute Method Post-tensioned slabs should have sufficient stiffness to resist excessive bending due to non-uniform swell and shrinkage of subgrade soils. The differential movement can occur at the corner, edge, or center of the slab. The potential for differential uplift can be evaluated using the 1997 UBC, Section 1816, based on design specifications of the Post-Tensioning Institute. The following table presents suggested minimum coefficients to be used in the Post-Tensioning Institute design method. Thornthwaite 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 Dr. Shahla Abedi APNs 216-290-20, 216-290-21, 216-130-68 File:e:\wp9\4000\4084a.pge W.O. 4084-A-SC January 13, 2004 Page 21 GeoSoiIs, Inc. 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 1997 UBC Section, 1816. 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. EXPANSION INDEX OF SOIL SUBGRADE em center lift em edge lift ym center lift ym edge lift MEDIUM EXPANSION (E.I. = 51-90) 5.5 feet 4.0 feet 2.7 inches |_ 0.75 inch HIGH EXPANSION (E.I. = 91-130) 5.5 feet 4.5 feet 3.5 inches 1.2 inches VERY HIGH (Critical) EXPANSION POTENTIAL (E.I. >130) 6.0 feet 4.5 feet 4.5 inches 1.6 inches Deepened footings/edges around the slab perimeter must be used to minimize non-uniform surface moisture migration (from an outside source) beneath the slab. An edge depth of 12 inches should be considered a minimum. 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. Should open bottom planters be planned directly adjacent to the foundation system, the values in the above tables would need to be reviewed and/or modified to reflect more highly variable moisture fluctuations along the edges of the foundations. CORROSION Upon completion of grading, additional testing of soils (including import materials) for corrosion to concrete and metals should be performed prior to the construction of utilities and foundations. Dr. Shahla Abedi APNs 216-290-20, 216-290-21, 216-130-68 File:e:\wp9\4000\4084a.pge W.O. 4084-A-SC January 13, 2004 Page 22 GeoSoils, Inc. DETAIL Provide surface drainage ±12' Water proofing menbrane (optional) (5) Veephole . Finished surface Native Backfill Slope or Level or flatter © WATER PROOFING MEMBRANE (optional)! Liquid boot or approved equivalent, © ROCK'. 3/4 to 1-1/2' (inches) rock, © FILTER FABRIC' Mirafi 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, (§) WEEPHDLEi 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 Geotechnical • Geologic • Environmental DETAIL Provide surface drainage I Water proofing nenbrane (optional)) Native Backfill Slope or Level Native Backfill Drain /4 or f later (5) Weephole Finished surface ®WATER PRDDFING MEMBRANE (optional): Liquid boot or approved equivalent, DRAIN: Miradrain 6000 or J-drain 200 or equivalent for non-waterproofed walls, Miradrain 6200 or J-drain 200 or equivalent for water proofed walls. FILTER FABRIG Mirafl 140N or approved equivalent place fabric flap behind core, (3) (4) PIPE: 4' (Inches) diameter perforated PVC, schedule 40 or approved alternative with minimum of IX gradient to proper outlet point, WEEPHDLEi Minimum 2' (inches) diameter placed at 20' (feet) on centers along the wall, and 3' (Inches) above finished surface, RETAINING WALL BACKFILL AND SUBDRAIN DETAIL GEOTEXTILE DRAIN DETAIL 2 Geotechnica! • Geologic • Environmental DETAIL Provide surface drainage /4 or flater N . T , S . Native Backfill Slope or Level IjWater proving membrane ' (optional) ((5) Weephole Finished surface Heel width Clean sand backfill 3) WATER PROOFING MEMBRANE (optional): Liquid boot or approved equivalent, © CLEAN SAND BACKFILL- Must have sand equivalent value of 30 or greaten can be denslfied by water Jetting. © FILTER FABRIC" Mlrafi 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) dlaneter perforated PVC. schedule 40 or approved alternative with nlnlnun of IX gradient to proper outlet point, (6) WEEPHOLEi Minimum 2' (Inches) dlaneter placed at 20' (feet) on centers along the wall, and 3' (Inches) above finished surface, <swe» RETAINING WALL AND SUBDRA1N DETAIL CLEAN SAND BACKFILL DETAIL 3 Geotechnical • Geologic • Environmental Wall/Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from cut to fill, the civil designer may specify either: a) A minimum of a 2-foot overexcavation and recompaction of cut materials for a distance of 2H, from the point of transition. b) Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints or crack control joints) such that a angular distortion of 1 /360 for a distance of 2H on either side of the transition may be accommodated. Expansion joints should be sealed with a flexible, non-shrink grout. c) Embed the footings entirely into native formational material (i.e..deepened footings). If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation "a" (above) and until such transition is between 45 and 90 degrees to the wall alignment. TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS AND EXPANSIVE SOILS Expansive Soils and Slope Creep Soils at the site are likely to be expansive and therefore, become desiccated when allowed to dry. Such soils are susceptible to surficial slope creep, especially with seasonal changes in moisture content. Typically in southern California, during the hot and dry summer period, these soils become desiccated and shrink, thereby developing surface cracks. The extent and depth of these shrinkage cracks depend on many factors such as the nature and expansivity of the soils, temperature and humidity, and extraction of moisture from surface soils by plants and roots. When seasonal rains occur, water percolates into the cracks and fissures, causing slope surfaces to expand, with a corresponding loss in soil density and shear strength near the slope surface. With the passage of time and several moisture cycles, the outer 3 to 5 feet of slope materials experience a very slow, but progressive, outward and downward movement, known as slope creep. For slope heights greater than 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. Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 28 llsf Inc. 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 for the concrete and mortarshould 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: 5-foot vertical zone below the slope face and projected upward parallel to the slope face. Creep Load: The creep load projected on the area of the grade beam should be taken as an equivalent fluid approach, having a density of 60 pcf. For the caisson, it should be taken as a uniform 900 pounds per linear foot of caisson's depth, located above the creep zone. Point of Fixity: Located a distance of 1.5 times the caisson's diameter, below the creep zone. Passive Resistance: Passive earth pressure of 300 psf per foot of depth per foot of caisson diameter, to a maximum value of 4,500 psf may be used to determine caisson depth and spacing, provided that they meet or exceed the minimum requirements stated above. To determine the total lateral resistance, the contribution of the creep prone zone above the point of fixity, to passive resistance, should be disregarded. Allowable Axial Capacity: Shaft capacity : 350 psf applied below the point of fixity over the surface area of the shaft. Tip capacity: 4,500 psf. Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 29 GeoSoils, Inc. EXPANSIVE SOILS, DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS The soil materials on site are likely to be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to flatwork and other improvements. The resulting potential for distress to improvements may be reduced, but not totally eliminated. To that end, it is recommended that the developer should notify any homeowners or homeowners association of this long-term potential for distress. To reduce the likelihood of distress, the following recommendations are presented for all exterior flatwork: 1. The subgrade area for concrete slabs should be compacted to achieve a minimum 90 percent relative compaction, and then be presoaked to 2 to 3 percentage points above (or 130 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, 1/2 to % inches deep, often enough so that no section is greater than 10 feet by 10 feet. For sidewalks or narrow slabs, control joints should be provided at intervals of every 6 feet. The slabs should be separated from the foundations and sidewalks with expansion joint filler material. 5. No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Concrete compression strength should be a minimum of 2,500 psi. Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216^290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 30 , Inc. 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 acontinuous source of moisture (i.e.,, irrigation, planters, etc.), all joints should be additionally sealed with flexible mastic. 7. Planters and walls should not be tied to the house. 8. Overhang structures should be supported on the slabs, or structurally designed with continuous footings tied in at least two directions. 9. Any masonry landscape walls that are to be constructed throughout the property should be grouted and articulated in segments no more than 20 feet long. These segments should be keyed or doweled together. 10. Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. 11. Positive site drainage should be maintained at all times. Finish grade on the lots should provide a minimum of 1 to 2 percent fall to the street, as indicated herein. It should be kept 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, 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. 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 Dr. ShahlaAfaedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 Rle:e:\wp9\4000\4084a.pge Page 31 GeoSoils, Inc. 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 UBC and/or California Building Code), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. All of these measures are recommended for design of structures and improvements. The ramifications of the above conditions, and recommendations for mitigation, should be provided to each homeowner and/or any homeowners association. Slope Maintenance and Planting Water has been shown to weaken the inherent strength of all earth materials. Slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Over-watering should be avoided as it can adversely affect site improvements, and cause perched groundwater conditions. Graded slopes constructed utilizing onsite materials would be erosive. Eroded debris may be minimized and surficial slope stability enhanced by establishing and maintaining a suitable vegetation cover soon after construction. Compaction to the face of fill slopes would tend to minimize short-term erosion until vegetation is established. Plants selected for landscaping should be light weight, deep rooted types that require little water and are capable of surviving the prevailing climate. Jute-type matting or other fibrous covers may aid in allowing the establishment of a sparse plant cover. Utilizing plants other than those recommended above will increase the potential for perched water, staining, mold, etc., to develop. A rodent control program to prevent burrowing should be implemented. Irrigation of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to each homeowner. Over-steepening of slopes should be avoided during building construction activities and landscaping. Drainage Adequate 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 Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 32 GeoSoUs, Inc. 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 with a moisture barrier to prevent penetration of irrigation water into the subgrade. Provisions should be made to drain the excess irrigation water from the planters without saturating the subgrade below or adjacent to the planters. Graded slope areas should be planted with drought resistant vegetation. Consideration should be given to the type of vegetation chosen and their potential effect upon surface improvements (i.e., some trees will have an effect on concrete flatwork with their extensive root systems). From a geotechnical standpoint leaching is not recommended for establishing landscaping. If the surface soils are processed for the purpose of adding amendments, they should be recompacted to 90 percent minimum relative compaction. Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 33 OeoSoils, Inc. 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 forthe 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. 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. Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 34 , Inc. Additional Grading This office should be notified in advance of any fill placement, supplemental regrading of the site, or trench backfilling after rough grading has been completed. This includes completion of grading in the street and parking areas and utility trench and retaining wall backfills. Footing Trench Excavation All footing excavations should be observed by a representative of this firm subsequent to trenching and prior to concrete form and reinforcement placement. The purpose of the observations is to verify that the excavations are made into the recommended bearing material and to the minimum widths and depths recommended for construction. If loose or compressible materials are exposed within the footing excavation, a deeper footing or removal and recompaction of the subgrade materials would be recommended 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 afactor in subsurface excavations and trenching. Shoring or excavating the trench walls at the angle of repose (typically 25 to 45 degrees) may be necessary and should be anticipated. All excavations should be observed by one of our representatives and minimally conform to CAL-OSHA and local safety codes. Utility Trench Backfill 1. 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. 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 Dr. ShahlaAbedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 35 GeoS&nst Inc. 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. • Priorto pouring any slabs orflatwork, 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. 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. Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 36 GeoSoils, Inc. 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 subject to change with time. GSI assumes no responsibility or liability for work ortesting performed by others, ortheir 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. Dr. Shahla Abedi W.O. 4084-A-SC APNs 216-290-20, 216-290-21, 216-130-68 January 13, 2004 File:e:\wp9\4000\4084a.pge Page 37 ^ Inc. GIBRALTAR STREET PRELIMINARY SITE DESIGN Artificial fill (undocumented) Quaternary terrace deposits (circled where buried) Approximate location of exploratory boring f\ t\ Approximate location of —— 1-J Qeologic cross section N.A.P. Not a part Base Map taken from "Preliminary Site Design", by O'Day Consultants, dated December 11, 2003. RIVERSIDE CO. ORANGE CO. SAN DIFOO CO GEOTECHNICAL MAP Plate 1 W.O. 4084-A-SC DATE .1/04 SCALE 1"=40- APPENDIX A REFERENCES APPENDIX A REFERENCES AEL, 1989, Geotechnical investigation, proposed parking/residential structure, Gibraltar Street, La Costa, California, Job Number 1-1-340, dated December 28. Blake, Thomas F., 2000a, EQFAULT, A computer program for the estimation of peak horizontal acceleration from 3-D fault sources; Windows 95/98 version. , 2000b, EQSEARCH, A computer program for the estimation of peak horizontal acceleration from California historical earthquake catalogs; Updated to December, 2002, Windows 95/98 version. , 2000c, FRISKSP, A computer program for the probabilistic estimation of peak acceleration and uniform hazard spectra using 3-D faults as earthquake sources; Windows 95/98 version. 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, Oakland, pp. 23-49, September 15. Campbell, K.W. and Bozorgnia, Y., 1997, Attenuation relations for soft rock conditions; jn EQFAULT, A computer program for the estimation of peak horizontal acceleration from 3-D fault sources; Windows 95/98 version, Blake, 2000a. Campbell, K.W., 1997, Empirical near-source attenuation relationships for horizontal and vertical components of peak ground acceleration, peak ground velocity, and pseudo-absolute acceleration response spectra, Seismological Research Letters, vol.68, No. 1,pp. 154-179. 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 zones maps; California Division of Mines and Geology Special Publication 42, with Supplements 1 and 2, 1999. International Conference of Building Officials, 1997, Uniform building code: Whittier, California, vol. 1, 2, and 3. Jennings, C.W., 1994, Fault activity map of California and adjacent areas: California Division of Mines and Geology, Map sheet no. 6, Scale 1:750,000. Joyner, W.B, and Boore, D.M., 1982a, Estimation of response-spectral values as functions of magnitude, distance and site conditions, m eds., Johnson, J.A., Campbell, K.W., and Blake, T.F.: AEG Short Course, Seismic Hazard Analysis, June 18, 1994. GeoSoils, Inc. , 1982b, Prediction of earthquake response spectra, U.S. Geological Survey Open-File Report 82-977, 16p. Kennedy, M.P. and Tan S.S., 1996, Geologic maps of the northwest part of San Diego County, California., Division of Mines and Geology, Plate 2, scale 1:24,000. O'Day Consultants, Inc., 2003, Gibraltar Street preliminary site design, 40-scale, Job number 031060, dated December 11. Sadigh, K., Egan, J., and Youngs, R., 1987, Predictive ground motion equations, |n Joyner, W.B. and Boore, D.M., 1988, measurement, characterization, and prediction of strong ground motion, |n Von Thun, J.L, ed., Earthquake engineering and soil dynamics II, recent advances in ground motion evaluation, American Society of Civil Engineers Geotechnical Special Publication No. 20, pp. 43-102. Sowers and Sowers, 1970, Unified soil classification system (After U. S. Waterways Experiment Station and ASTM 02487-667) ]n Introductory Soil Mechanics, New York. Dr. Shahla Abedi Appendix A File:e:\wp9\4000\4084a.pge Page 2 Inc. APPENDIX B BORING LOGS BORING LOG GeoSoils, Inc. IV. O. 4084-A-SC PROJECT: ABED1 BORING B-1 SHEET 1 OF 1 Gibraltar Street, Carlsbad DA TE EXCA VA TED 1 2-7-03 c si 8 - 5- 20- 25- 30- Sample ^13 CD «"S TlS 5l ^ M m m ~3>5 0m 29 25 56 70 50-1" wEO Pw 1,r> CO CL CH CL . 5-5 ?- Q. ^ £<Q 114.2 109.0 106.3 115.0 ? £3 O 15.0 18.3 19.3 15.9 ^c 0 ro 3 toCO 88.4 93.7 92.0 96.1 SAMPLE METHOD: 140 LB. HAMMER @ 30" DROP Standard Penetration Test V Groundwater Y//A Undisturbed, Ring Sample Description of Material w '%, ww/,.I ARTIFICIAL FILL: @ 0' SANDY CLAY, olive brown, dry to damp, soft; occasional subrounded to subangular pebble sized clasts, nonuniform. @ 3' CLAY, dark brown, moist, very stiff; nonuniform. @ 6' CLAY, dark brown to olive brown, moist, very stiff; nonuniform. @ 8>2 CLAY w/SAND, dark gray brown, moist, very stiff; nonuniform. QUATERNARY TERRACE DEPOSITS: @ 10' Interbedded CLAYEY SAND/SANDY CLAY, olive gray to orange, moist, dense/hard; iron oxide staining, caliche blebs. @ 15' No recovery due to rock. Practical Refusal @ 1 5' No Groundwater/Caving Encountered Backfilled 12-7-2003 With 2 Bags Bentonite Chips and Cuttings Gibraltar Street, Carlsbad oeOoOIIS, me. PLATE B1 BORING LOG GeoSoils, Inc. W.O. 4084-A-SC PROJECT: ABEDI BORING B-2 SHEET 1 OF 1 Gibraltar Street, Carlsbad DA TE EXCA VA TED 1 2-7-03 £ .c & — - 10- - - 15- - - - 20- 25- 30- Sample 3m '""2 5a ^ //// . In30en 30 371 50-4V21 coRO pw §, D CO CL CH SM CUSP ^ .t± Q.5 ^^ D 110.3 105.3 ? CD 2 O 15.0 7.2 ^cg ro roCO 79.4 33.4 SAMPLE METHOD: 140 LB. HAMMER @ 30" DROP Standard Penetration Test ..... -*- Groundwater YvA Undisturbed, Ring Sample Description of Material xWv/xx '////, '////, rft yk•__^ • £: - wnni ARTIFICIAL FILL: @ 0' SANDY CLAY w/GRAVEL, brown, dry to damp, medium stiff; abundant subangular pebble to cobble sized clasts, slow drilling due to the abundance of gravel, nonuniform. @ 3' CLAY w/SAND, medium brown to dark brown, moist, stiff; abundant subangular pebble to cobble sized clasts, nonuniform. @ 5' SILTY SAND w/CLAY, yellow brown, moist, medium dense; occasional organics, nonuniform. QUATERNARY TERRACE DEPOSITS: @ 10' CLAY, gray, moist, hard; coarsening downward to SAND, yellow brown, dry, very dense; friable, occasional subrounded pebble sized clasts, occasional root casts. @ 141/i' Practical refusal due to rock. Total Depth = 141/2' No Groundwater/Caving Encountered Backfilled 12-7-2003 With 3 Bags Bentonite Chips and Cuttings Gibraltar Street, Carlsbad O6OOO IS, DC. PLATE B2 GeoSoils, Inc. PROJECT: ABEDI Gibraltar Street, Carlsbad g. -C "a. <DD - 5- 1* 30- Sample ^3ED lj *S 11 m m m //// m u Blows/ft.28 28 36 40 35-5" 30 coSO Fw >,3 CO CL CH/CL CL/CH CUSC Dry Unit Wt.(pcf)111.0 100.2 108.2 107.7 Moisture (%)14.3 20.8 19.6 10.2 13.9 Saturation (%)77.1 98.1 50.3 BORING LOG W.O. 4084-A-SC BORING B-3 SHEET 1 OF 1 DA TE EXCA VA TED 12-7-03 SAMPLE METHOD: 140 LB. HAMMER @ 30" DROP I m ] Standard Penetration Test , -^- Groundwater \ Undisturbed, Ring Sample Description of Material J 1 ^ ARTIFICIAL FILL: @ 0' SANDY CLAY, yellow brown, dry to moist, soft; occasional subangular pebble sized clasts, nonuniform. @ 3' SANDY CLAY, yellow brown to olive gray to dark brown, moist, very stiff; occasional subangular pebble sized clasts, nonuniform. @ 6' CLAY w/SAND to SANDY CLAY, olive brown to dark brown, moist, very stiff; nonuniform. @ 10' CLAY w/SAND to SANDY CLAY, olive brown to dark gray brown to dark brown, moist, very stiff; nonuniform. QUATERNARY COLLUVIUM: @ 15' SANDY CLAY, dark gray brown, damp, hard; porous fining downward to CLAY, dark gray brown, moist, hard; occasional subangular pebble sized clasts, organic odor, slightly porous. QUATERNARY TERRACE DEPOSITS: @ 20' SANDY CLAY, dark gray brown to olive gray, moist, hard; coarsening downward to CLAYEY SAND, olive gray to orange, moist, very dense; iron oxide staining, no recovery due to rocks. @ 25' Interbedded SANDY CLAY to CLAYEY SAND, olive gray to orange, moist, very stiff to medium dense; occasional A subangular pebble sized clasts, iron oxide staining. _f @ 26/4' Practical refusal due to rock. Total Depth = 261/2' No Groundwater/Caving Encountered Backfilled 12-7-2003 With 2 Bags Bentonite Chips and Cuttings Gibraltar Street, Carlsbad GeOSOJlS, lflC. p/^rE B3 BORING LOG GeoSoils, Inc. W.O. 4084-A-SC PROJECT: ABEDI BORING B-4 SHEET 1 OF 1 Gibraltar Street, Carlsbad DA TE EXCA VA TED 1 2-7-03 3= ^ CDD — - - 10- _ 15- _ - 20- 25- 30- Sample m to"° Is ^ ^ H ^ it:"Ss0m 37 35/ 50-2" 72 50-6" CO EO Fw g,D W CL CH SC/CL SP . -> o±i Q. Q 104.8 108.4 116.9 103.5 ;£• aT D 0 20.1 22.2 13.8 7.6 g. cp CO 13 CDCO 92.1 111.7 88.2 33.7 SAMPLE METHOD: 1 40 LB. HAMMER @ 30" DROP Standard Penetration Test __. V. Groundwater fc/y/\ Undisturbed, Ring Sample Description of Material WI ^ ARTIFICIAL FILL: @ 0' SANDY CLAY, olive brown, dry to moist, soft to stiff; nonuniform. @ 5' CLAY w/SAND, olive brown to olive gray, moist, very stiff; nonuniform. QUATERNARY COLLUVIUM: @ 71/2' CLAYEY SAND to SANDY CLAY, dark brown, moist, very dense/hard. QUATERNARY TERRACE DEPOSITS: @ 10' Interbedded CLAYEY SAND/SANDY CLAY, olive gray to yellow brown to orange, moist, dense; iron oxide staining. @ 15' SAND w/CLAY, olive gray to orange, moist dense; iron A oxide staining, poorly graded SAND. /~ Total Depth = 16' No Groundwater/Caving Encountered Backfilled 12-7-2003 With 11/2 Bags Bentonite Chips and Cuttings Gibraltar Street, Carlsbad oeOOOIIS, IMC. PLATE B4 APPENDIX C EQFAULT, EQSEARCH, AND FRISKSP MAXIMUM EARTHQUAKES ABEDI 1 c CDOO .1 .01 .001 .1 x X X X X 1 10 Distance (mi) 100 W.O. 4084-A-SC Plate C-1 (0o> 0 LLI <4— O1_ 0 E ZS <D "-^JO 13 EE^O EARTHQUAKE RECURRENCE CURVE 100 10 .01 .001 ABEDI JJ_I I I I I I * 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. 4084-A-SC Plate C-2 EARTHQUAKE EPICENTER MAP ABEDI 1100 1000 4- 900 -h 800 4- 700 600 4- 500 4 400 4- 300 4- 200 4- 100 4 0 + -100 I I I I I I I I I I I I I I I I I I I I I I I I I I -400 -300 -200 -100 100 200 300 400 500 600 W.O. 4084-A-SC Plate C-3 PROBABILITY OF EXCEEDANCE CAMP. & BOZ. (1997 Rev.) SR 1 100 ^ vO > COno ol 0oc CO 00o X UJ 90 80 70 60 50 40 30 20 10 75 yrs 100 yrs 0.00 0.25 0.50 0.75 1.00 1.25 1.50 Acceleration (g) W.O. 4084-A-SC Plate C-4 jg oCO to O RETURN PERIOD vs. ACCELERATION CAMP. & BOZ. (1997 Rev.) SR 1 10000000 1000000 100000 10000 1000 100 0 Q_ 0o: £01^<D o Oi 0.00 0.25 0.50 0.75 1.00 Acceleration (g) 1.25 1.50 APPENDIX D LABORATORY DATA 3,000 2,500 2,000 O 1 1,500 00 OL 2j CO 1,000 500 500 1,000 1,500 2,000 2,500 3,000 NORMAL PRESSURE, psf Sample "i1 • B-3 B-3 Depth/El. 10.0 10.0 Primary/Residual Shear Primary Shear Residual Shear Sam pie Type Remolded Remolded Yd 102.9 102.9 MC% 13.0 13.0 C 468 475 + 22 22 Note: Sample Innundated prior to testing GeoSoils, Inc. GeoSoils, Inc. 5741 Palmer Way Carlsbad, CA 92008 Telephone: (760)438-3155 Fax: (760)931-0915 DIRECT SHEAR TEST Project: ABEDI Number: 4084-A-SC Date: December 2003 Plate D-1 60 50 I 40 2 t p 30 CO 5o_ 20 10 CL-i/IL CL ML CH MH 20 40 60 LIQUID LIMIT 80 100 Sample Depth/El.LL PL PI Fines Classification B-1 5.0 50 16 34 GeoSoils, Inc. ' GeoSoils, Inc. 5741 Palmer Way Carlsbad, CA 92008 Telephone: (760)438-3155 Fax: (760)931-0915 ATTERBERG LIMITS' RESULTS Project: ABEDI Number: 4084-A-SC Date: December 2003 Plate D-2 STRAIN, %• 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 1C)0 Sample Depth/El. B-3 15.0 ~— —-—-i ( >^ V ^^ \ ^^^^ "•v ^i^X < "\J » \\ ^ 1,000 STRESS, psf Visual Classification Sandy Clay GeoSoils, Inc. ,j,~« x "• ., - 5741 Palmer Way GeoSoils, Inc. Carlsbad, CA 92008 ••• •*/* ' - -• ' »» Telephone: (760) 438-31 55 Fax: (760)931-0915 \ \ '^~~ i \ \\ -~ — — \\ — — \\— i > • 10,000 Yd Initial 107.7 MC Initial 10.2 MC Final 18.5 H20 2000 CONSOLIDATION TEST Project: ABEDI Number: 4084-A-SC Date: December 2003 Plate D-3 APPENDIX E SLOPE STABILITY ANALYSIS APPENDIX E 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 Mohr-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. GeoSoilSj 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 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. 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. 2. Slope geometry and surcharge boundary loads. 3. Apparent dip of bedding plane can be specified in angular range (i.e., from 0 to 90 degrees. 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 confined areas may respond essentially as rigid structures; (2) an earthquake's inertiaforce is enacted on a mass for a short time period. Therefore, replacing a transient force by a pseudo-static force representing the maximum acceleration is considered unrealistic; (3) Assuming that total pseudo-static loading is applied evenly throughout the embankment for an extended period of time is an incorrect assumption, as the length of the failure Dr. Shahla Abedi Appendix E File:e:\wp9\4000\4084a.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. Factors of safety for the ten most critical surfaces for static and 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 through E-3. Atypical cross-section representing the existing slope configuration was utilized for analyses. Dr. Shahla Abedi Appendix E File:e:\wp9\4000\4084a.pge Page 3 GeoSoilSj Inc. TABLE E-1 SOIL PARAMETERS USED SOIL MATERIALS AND LOCATION Artificial Fill (Undocumented) (SANDY CLAY/CLAY [CL/CH]) B-3 ©10-12' (remolded) PEAK VALUES C (psf) 150* 0 (degrees) 18* *Based on the relative compaction and non-uniform nature of the existing undocumented fill material being generally below the current industry standard of 90 percent relative compaction (and placed upon unsuitable bearing soils [i.e., colluvium] in localized areas), slope gradients that are steeper than 2:1 (h:v), and the observed slope creep, reasonable values were utilized for our slope stability analysis. TABLE E-2 SUMMARY OF SLOPE ANALYSIS STABILITY Gross Surficial SLOPE CONFIGURATION ±15-FootHigh Existing Fill Slope Along Northwestern Margin of Site ± 15-Foot High Existing Fill Slope Along Northwestern Margin of Site SLOPE GRADIENT 1.7:1 1.7:1 FACTORS OF SAFETY STATIC 1.43 .98 SEISMIC 1.13 N/A REMARKS Bishop, modified Grossly unstable in present condition. Existing fill slopes will require reconstruction to comply with current industry standards. Surficially unstable in present condition. Existing fill slopes will require reconstruction in order to comply with current industry standard and to minimize long term maintenance. Dr. Shahla Abedi File:e:\wp9\4000\4084a.pge Appendix E Page 4 GeoSoils, Inc. o00 V)o 140 120 - 100 ABEDI- UNDOCUMENTED FILL/COLLUVIUM SECTION A-A1 - STATIC C:\STEDWIN\ABEDI.PL2 Run By: GEOSOILS 12/16/03 11:31AM i # FS a 1.43 b 1.43 c 1.44 d 1.44 - e 1.45 f 1.45 R 1.45 h 1.45 i 1.45 j 1.46 i 1 1 Soil Soil Total Saturated Desc. Type Unit Wt. Unit Wt. No. (pcf) (pcf) Afu 1 120.0 125.0 Qcol 2 120.0 125.0 Qt 3 120.0 125.0 1 — H , Cohesion Friction Piez. Intercept Angle Surface (psf) (deg) No. 150.0 18.0 0 100.0 18.0 0 150.0 28.0 0 1 ' 1 1 1 TJ 0) !•*(D m 160 180 200 GSTABL7 v.2 FSrnin=1.43 Safety Factors Are Calculated By The Modified Bishop Method o CO COo 140 120 100 80 ABEDI- UNDOCUIV1ENTED FILL/COLLUVIUIV1 SECTION A-A' - SEISMIC C:\STEDWIN\ABEDIS.PL2 Run By: GEOSOILS 12/16/03 11:33AM *ws,o M«5T*• M # a b c d e f Rh i i FS 1.131.13 1.13 1.13 1.14 1.14 1.14 1.14 1.14 1.14 Soil Desc. Afu Qcol Qt Soil Type No. 1 2 3 Total Unit Wt. (pcf) 120.0 120.0 120.0 Saturated Unit Wt. (pcf) 125.0 125.0 125.0 Cohesion Intercept (psf) 150.0 100.0 150.0 Friction Angle (deg) 18.0 18.0 28.0 Piez. Surface No. 0 0 0 Load Value Horiz Eqk 0.120 g< T3 0)it-<t> m 20 - u 0 STED 20 40 60 Safety Factors 80 100 120 GSTABL7 v.2 FSmin=l.l3 Are Calculated By The Modified 140 160 Bishop Method 180 200 /— lii O00 SURFICIAL SLOPE STABILITY FOR FILL SLOPES d§toQ IwoSLOPE ANGLE i (degrees) = VERTICAL DEPTH OF SATURATION z (ft) = SATURATED SOIL UNIT WEIGHT ysat (pcf)= UNIT WEIGHT OF WATER yw (pcf) = EFFECTIVE COHESION C' (psf) = EFFECTIVE FRICTION ANGLE $ (degrees)^ SLOPE ANGLE IN RADIANS EFFECTIVE FRICTION ANGLE IN RADIANS FACTOR OF SAFETY = INPUT PARAMETERS 30.46 4 120 62.4 150 18 OUTPUT CALCULATIONS 0.531627 0.314159 0.98 o>i-+ (0 m APPENDIX F GENERAL EARTHWORK AND GRADING GUIDELINES GENERAL EARTHWORK AND GRADING GUIDELINES General These guidelines present general procedures and requirements for earthwork and grading as shown on the approved grading plans, including preparation of areas to filled, placement of fill, installation of subdrains and excavations. The recommendations contained in the geotechnical report are part of the earthwork and grading guidelines and would supercede the provisions contained hereafter in the case of conflict. Evaluations performed by the consultant during the course of grading may result in new recommendations which could supersede these guidelines or the recommendations contained in the geotechnical report. The contractor is responsible for the satisfactory completion of all earthwork in accordance with provisions of the project plans and specifications. The project soil engineer and engineering geologist (geotechnical consultant) or their representatives should provide observation and testing services, and geotechnical consultation during the duration of the project. EARTHWORK OBSERVATIONS AND TESTING Geotechnical Consultant Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer and engineering geologist) should be employed for the purpose of observing earthwork procedures and testing the fills for conformance with the recommendations of the geotechnical report, the approved grading plans, and applicable grading codes and ordinances. The geotechnical consultant should provide testing and observation so that determination may be made that the work is being accomplished as specified. It is the responsibility of the contractor to assist the consultants and keep them apprised of anticipated work schedules and changes, so that they may schedule their personnel accordingly. All clean-outs, prepared ground to receive fill, key excavations, and subdrains should be observed and documented by the project engineering geologist and/or soil engineer prior to placing and fill. It is the contractors's responsibility to notify the engineering geologist and soil engineer when such areas are ready for observation. Laboratory and Field Tests Maximum 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 properly mixed and moisture Dr. Shahla Abedi Appendix F File:e:\wp9\4100\4184a.pge Page 2 GeoSofls, Inc. conditioned should be re-compacted to the minimum relative compaction as specified in these guidelines. Existing ground which is determined to be satisfactory for support of the fills should be scarified to a minimum depth of 6 inches or as directed by the soil engineer. After the scarified ground is 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 1/2the 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 Dr. Shahla Abedi Appendix F File:e:\wp9\4100\4184a.pge Page 3 GeoSoils, Inc. characteristics may be designated by the consultant as unsuitable and may require blending with other soils to serve as a satisfactory fill material. Fill materials derived from benching operations should be dispersed throughout the fill area and blended with other bedrock derived material. Benching operations should not result in the benched material being placed only within a single equipment width away from the fill/bedrock contact. Oversized materials defined as rock or other irreducible materials with a maximum dimension greater than 12 inches should not be buried or placed in fills unless the location of materials and disposal methods are specifically approved by the soil engineer. Oversized material should betaken 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. Dr. Shahla Abedi Appendix F File:e:\wp9\4100\4184a.pge Page 4 GeoSoils, Inc. Where tests indicate that the density of any layer of fill, or portion thereof, is below the required relative compaction, or improper moisture is in evidence, the particular layer or portion shall be re-worked until the required density and/or moisture content has been attained. No additional fill shall be placed in an area until the last placed lift of fill has been tested and found to meet the density and moisture requirements, and is approved by the 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 an alternative to over-building and cutting back the compacted fill slopes is selected, then special effort should be made to achieve the required compaction in the outer 10 feet of each lift of fill by undertaking the following: 1. An extra piece of equipment consisting of a heavy short shanked sheepsfoot should be used to roll (horizontal) parallel to the slopes continuously as fill is placed. The sheepsfoot roller should also be used to roll perpendicular to the slopes, and extend out over the slope to provide adequate compaction to the face of the slope. 2. Loose fill should not be spilled out over the face of the slope as each lift is compacted. Any loose fill spilled over a previously completed slope face should be trimmed off or be subject to re-rolling. 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. Dr. Shahla Abedi Appendix F File:e:\wp9\4100\4184a.pge Page 5 GeoSoils, Inc. 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. SUBDRA1N 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 priorto 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. Dr. Shahla Abedi Appendix F File:e:\wp9\4100\4184a.pge Page 6 GeoSoils, Inc. 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 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 forthe 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. Dr. Shahla Abedi Appendix F File:e:\wp9\4100\4184a.pge Page 7 GeoSoils, Inc. Flashing Lights: All vehicles stationary in the grading area shall use rotating or flashing amber beacon, or strobe lights, on the vehicle during all field testing. While operating a vehicle in the grading area, the emergency flasher on the vehicle shall be activated. In the event that the contractor's representative observes any of our personnel not following the above, we request that it be brought to the attention of our office. Test Pits Location, Orientation and Clearance The technician is responsible for selecting test pit locations. A primary concern should be the technicians's safety. Efforts will be made to coordinate locations with the grading contractors authorized representative, and to select locations following or behind the established traffic pattern, preferably outside of current traffic. The contractors authorized representative (dump man, operator, supervisor, grade checker, etc.) should direct excavation of the pit and safety during the test period. Of paramount concern should be the soil technicians safety and obtaining enough tests to represent the fill. Test pits should be excavated so that the spoil pile is placed away form oncoming traffic, whenever possible. The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This necessitates the fill be maintained in a driveable condition. Alternatively, the contractor may wish to park a piece of equipment in front of the test holes, particularly in small fill areas or those with limited access. A zone of non-encroachment should be established for all test pits. No grading equipment should enter this zone during the testing procedure. The zone should extend approximately 50 feet outward from the center of the test pit. This zone is established for safety and to avoid excessive ground vibration which typically decreased test results. When taking slope tests the technician should park the vehicle directly above or below the test location. If this is not possible, a prominent flag should be placed at the top of the slope. The contractor's representative should effectively keep all equipment at a safe operation distance (e.g., 50 feet) away from the slope during this testing. The technician is directed to withdraw from the active portion of the fill as soon as possible following testing. The technician's vehicle should be parked at the perimeter of the fill in a highly visible location, well away from the equipment traffic pattern. The contractor should inform our personnel of all changes to haul roads, cut and fill areas or other factors that may affect site access and site safety. In the event that the technicians safety is jeopardized or compromised as a result of the contractors failure to comply with any of the above, the technician is required, by company policy, to immediately withdraw and notify his/her supervisor. The grading contractors Dr. Shahla Abedi Appendix F File:e:\wp9\4100\4184a.pge Page 8 GeoSoils, Inc. representative will eventually be contacted in an effort to effect a solution. However, in the interim, no further testing will be performed until the situation is rectified. Any fill place can be considered unacceptable and subject to reprocessing, recompaction or removal. In the event that the soil technician does not comply with the above or other established safety guidelines, we request that the contractor brings this to his/her attention and notify this office. Effective communication and coordination between the contractors representative and the soils technician is strongly encouraged in order to implement the above safety plan. Trench and Vertical Excavation It is the contractor's responsibility to provide safe access into trenches where compaction testing is needed. Our personnel are 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 fails to provide safe access to trenches for compaction testing, our company policy requires that the soil technician withdraw and notify his/her supervisor. The contractors representative will eventually be contacted in an effort to effect a solution. All backfill not tested due to safety concerns or other reasons could be subject to reprocessing and/or removal. If GSI personnel become aware of anyone working beneath an unsafe trench wall or vertical excavation, we have a legal obligation to put the contractor and owner/developer on notice to immediately correct the situation. If corrective steps are not taken, GSI then has an obligation to notify CAL-OSHA and/or the proper authorities. Dr. Shahla Abedi Appendix F Fi!e:e:\wp9\4100\4184a.pge Page 9 GeoSoils, Inc. CANYOiN SUBDRAIN DETAIL TYPE A PROPOSED COMPACTED FILL •NATURAL GROUND COLLUVIUM AND ALLUVIUM (REMOVE) BEDROCK TYPICAL BENCHING f/> SEE ALTERNATIVES TYPE B PROPOSED COMPACTED FILL •NATURAL GROUND COLLUVIUM AND ALLUVIUM (REMOVE) BEDROCK TYPICAL BENCHING SEE ALTERNATIVES NOTE: ALTERNATIVES, LOCATION AND EXTENT OF SUBDRAINS SHOULD BE DETERMINED BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST D URING GRADING. PLATE EG-1 CANYON SUBDRAIN ALTERNATE DETAILS ALTERNATE 1: PERFORATED PIPE AND FILTER MATERIAL UIMIM.IMMINIMUM A— 1M 12* MINIMUM FILTER MATERIAL MINIMUM VOLUME OF 9 FT.J /LINEAR FT. 6' t ABS OR PYC PIPE OR APPROVED SUBSTITUTE WITH MINIMUM 8 11/4' fl PERFS LINEAR FT. IN BOTTOM HALF OF PIPE. ASTM D2751. SDR 35 OR ASTM D1527. SCHD, 40 ASTM D3034. SDR 35 OR ASTM D1785, SCHD. 40 FOR CONTINUOUS RUN IN EXCESS OF 560 FT. USE Z'ff PIPE 6'MINIMUM B-1 FILTER MATERIAL. SIEVE SIZE PERCENT PASSING 1 INCH :100 3/4 INCH 90-100 3/8 INCH 40-100 NO. 4 25-40. NO. 8 18-33 .NO. 30 -5-15 "NO. 50 .0-7 NO. 200 0-3 ALTERNATE 2: PERFORATED PIPE, GRAVEL AND.FILTER FABRIC 6'MINIMUM OVERLAP 6• MINIMUM COVER 4' MINIMUM BEDDING 6'MINIMUM OVERLAP A-2 B-2 4- MINIMUM BEDDING GRAVEL'MATERIAL 9 FP/LINEAR FT. PERFORATED PIPE SEE ALTERNATE 1 GRAVEL' CLEAN 3/4 INCH ROCK OR APPROVED SUBSTITUTE FILTER FABRIC: MIRAFI 140 OR APPROVED SUBSTITUTE PLATE EG-2 DETAIL FOR FILL SLOPE TOEING OUT ON FLAT ALLUVIATED CANYON TOE OF SLOPE AS SHOWN ON GRADING PLAN .ORIGINAL GROUND SURFACE TO BE RESTORED WITH COMPACTED FILL BACKCUTVARIES. FOR DEEP REMOVALS. BACKCUT ^VKSHOULD BE MADE NO STEEP ER-THAN\1:1 OR AS NECESSARY FOR SAFETY CONSIDERATIONS / COMPACTED RLL ORIGINAL GROUND SURFACE ANTICIPATED ALLUVIAL REMOVAL DEPTH PER SOIL ENGINEER. Vl PROVIDE A 1:1 MINIMUM PROJECTION FROM TOE OF SLOPE AS SHOWN ON GRADING PLAN TO THE RECOMMENDED REMOVAL DEPTH. SLOPE HEIGHT. SITE CONDITIONS AMD/OR LOCAL CONDITIONS COULD DICTATE FLATTER PROJECTIONS REMOVAL ADJACENT TO EXISTING FILL ADJOINING CANYON FILL PROPOSED ADDITIONAL COMPACTED FILL COMPACTED FILL LIMITS LINE TEMPORARY COMPACTED FILL \FOR DRAINAGE ONLY Oaf °<£x Qaf ,'Qal (TO BE REMOVED) (EXISTING COMPACTED FILL) <^\ / ) BE REMOVED BEFORE Qaf ARTIFICIAL FILL PLACING ADDITIONAL COMPACTED FILL Qal ALLUVIUM PLATE EG-3 TYPICAL STABILIZATION / BUTTRESS FILL DETAIL 151 TYPICAL 1-2' CLEA m moI OUTLETS TO BE SPACED AT 100' MAXIMUM INTERVALS. AND SHALL EXTEND 12' BEYOND THE FACE OF SLOPE AT TIME OF. ROUGH GRADING COMPLETION. DESIGN FINISH SLOPE 15'MINIMUM BLANKET FILL IF RECOMMENDED BY THE SOIL ENGINEER 10'MINIMUM 25'MAXIMU BUTTRESS OR SIDEHILL FILL 1-J TYPICAL BENCHING HEEL W=15'MINIMUM OR H/2 X4- DIAMETER NON-PERFORATED OUTLET PIPE AND BACKDRAIN (SEE ALTERNATIVES) BEDROCK I 3'MINIMUM KEY DEPTH TYPICAL STABILIZATION / BUTTRESS SUBDRAIN DETAIL 4' MINIMUM 2'MINIMUM PIPE MINIMUM PIPE TJ m m CD I 01 (N 2' MINIMUM FILTER MATERIAL: MINIMUM OF FIVE FI'/LINEAR Ft OF PIPF OR FOUR Ft'/LINEAR Ft OF PIPE WHEN PLACED IN SQUARE CUT TRENCH. ALTERNATIVE IN LIEU OF FILTER MATERIAL: GRAVEL MAY BE ENCASED IN APPROVED FILTER FABRIC. FILTER FABRIC SHALL BE MIRAFI UO OR EQUIVALENT. FILTER FABRIC SMALL BE LAPPED A MINIMUM OF 12' ON ALL JOINTS. MINIMUM 4' DIAMETER PIPE: ABS-ASTM D-2751, SDR 35 OR ASTM D-1527 SCHEDULE 40 PVC-ASTM D-3034, SpR 35 OR ASTM D-1785 SCHEDULE 40 WITH A CRUSHING STRENGTH OF 1,000 POUNDS MINIMUM. AND A MINIMUM OF 8 UNIFORMLY SPACED PERFORATIONS PER FOOT OF PIPE INSTALLED WITH PERFORATIONS OF BOTTOM OF PIPE. PROVIDE CAP AT UPSTREAM END OF PIPE. SLOPE AT 2% TO OUTLET PIPE, OUTLET PIPE TO BE CONNECTED TO SUBDRAIN PIPE WITH TEE OR ELBOW. NOTE: 1. TRENCH FOR OUTLET PIPES TO BE BACKFILLEDi WITH ON-SITE SOIL 2. BACKDRAINS AND LATERAL DRAINS SHALL BE LOCATED AT ELEVATION OF EVERY BENCH DRAIN. , FIRST DRAIN LOCATED AT ELEVATION JUST ABOVE LOWER LOT GRADE. ADDITIONAL DRAINS MAY BE REQUIRED AT THE DISCRETION OF THE SOILS ' ENGINEER AND/OR ENGINEERING GEOLOGIST. FILTER MATERIAL SHALL BE OF THE FOLLOWING SPECIFICATION OR AN APPROVED EQUIVALENT: SIEVE SIZE PERCENT PASSING 1 INCH 3/4 INCH 3/8 INCH NO. 4 NO. 8 NO. 30 NO. 50 NO. 200 100 90-100 40-100 25-40 18-33 5-15 0-7 0-3 GRAVEL SHALL BE OF THE FOLLOWING SPECIFICATION OR AN APPROVED EQUIVALENT: SIEVE SIZE PERCENT PASSING 1 1/2 INCH NO. 4 NO. 200 100 50 8 SAND EQUIVALENT: MINIMUM OF 51 FILL OVER NATURAL DETAIL SIDEHILL FILL PROPOSED GRADE TOE OF SLOPE AS SHOWN ON GRADING PLAN PROVIDE A i:i MINIMUM PROJECTION FROM DESIGN TOE OF SLOPE TO TOE OF KEY AS SHOWN ON AS BUILT . "TJ COMPACTED FILL MAINTAIN MINIMUM 15' WIDTH SLOPE TO BENCH/BACKCUT NATURAL SLOPE TO BE RESTORED WITH COMPACTED FILL BACKCUT VARIES . MINIMUM BENCH WIDTH MAY VARY NOTE; 1, WHERE THE NATURAL SLOPE APPROACHES OR EXCEEDS THE MINIMUM KEY WIDT 2'X 3*MINIMUM KEY DEPTH m mo I CD 2* MINIMUM IN BEDROCK OR APPROVED MATERIAL. DESIGN SLOPE RATIO. SPECIAL RECOMMENDATIONS WOULD BE PROVIDED BY THE SOILS ENGINEER. 2, THE NEED FOR AND DISPOSITION OF DRAINS WOULD BE DETERMINED BY THE SOILS ENGINEER BASED UPON EXPOSED CONDITIONS. FILL OVER CUT DETAIL CUT/FILL CONTACT 1. AS SHOWN ON GRADING PLAN 2. AS SHOWN ON AS BUILT MAINTAIN MINIMUM 15'FILL SECTION FROM BACKCUT TO FACE OF FINISH SLOPE PROPOSED GRADE ORIGINAL TOPOGRAPHY BEDROCK OR APPROVED MATERIAL ILOWEST BENCH WIDTH 15'MINIMUM OR H/2 BENCH WIDTH MAY VARY "D m moI NOTE: THE CUT PORTION OF THE SLOPE SHOULD BE EXCAVATED AND EVALUATED BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST PRIOR TO CONSTRUCTING THE FILL PORTION. ~D m mo I 00 STABILIZATION FILL FOR UNSTABLE MATERIAL EXPOSED IN PORTION OF CUT SLOPE PRPOSED FINISHED GRADE" REMOVE: UNSTABLE MATERIAL REMOVE: UNSTABLE MATERIAL UNWEATHERED BEDROCK OR APPROVED MATERIAL COMPACTED STABILIZATION FILL 1* MINIMUM TILTED BACK• IF RECOMMENDED BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST, THE REMAINING CUT PORTION OF THE SLOPE MAY REQUIRE REMOVAL AND REPLACEMENT WITH COMPACTED FILL NOTE: 1. SUBDRAINS ARE NOT REQUIRED UNLESS SPECIFIED BY SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST, 2. 'Wr SHALL BE EQUIPMENT WIDTH I151) FOR SLOPE HEIGHTS LESS THAN 25 FEET. FOR SLOPES GREATER' THAN 25 FEET "W SHALL BE DETERMINED BY THE PROJECT SOILS ENGINEER AND /OR ENGINEERING GEOLOGIST. AT NO TIME SHALL 'W BE LESS THAN H/2. SKIN FILL OF NATURAL GROUND ORIGINAL SLOPE 'ROPOSED FINISH GRADE 15'MINIMUM TO BE MAINTAINED FROM PROPOSED FINISH SLOPE FACE TO BACKCUT PROPOSED FINISH SLOPE BEDROCK OR APPROVED MATERIAL T) NIMUM KEY WIDTH " 2'MINIMUM j KEY DEPTH MINIMUM KEY DEPTH m mCD I CO NOTE: 1. THE NEED AND DISPOSITION OF DRAINS WILL BE DETERMINED-1 BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST BASED ON FIELD CONDITIONS. 2. PAD OVEREXCAVATION AND RECOMPACTION SHOULD BE PERFORMED IF DETERMINED TO BE NECESSARY BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST. DAYLIGHT CUT LOT DETAIL NATURAL GRADE PROPOSED FINISH GRADE |3f MINIMUM BLANKET FILL TYPICAL BENCHING MINIMUM DEPTH 2% GRADIENT RECONSTRUCT COMPACTED FILL SLOPE AT 2M OR FLATTER (MAY INCREASE OR DECREASE PAD AREA). OVEREXCAVATE AND RECOMPACT REPLACEMENT FILL AVOID AND/OR CLEAN UP SPILLAGE OF MATERIALS ON THE NATURAL SLOPE BEDROCK OR APPROVED MATERIAL TJ Hm mo NOTE: 1. SUBDRAIN AND KEY WIDTH REQUIREMENTS WILL BE DETERMINED BASED ON EXPOSED SUBSURFACE CONDITIONS AND THICKNESS OF OVERBURDEN. 2. PAD OVER EXCAVATION AND RECOMPACTION SHOULD BE PERFORMED IF DETERMINED NECESSARY BY THE SOILS ENGINEER AND/OR THE ENGINEERING GEOLOGIST. o TRANSITION LOT DETAIL CUT LOT (MATERIAL TYPE TRANSITION] NATURAL GRADE COMPACTED FILL OVEREXCAVATE AND RECOMPACT UNWEATHERED BEDROCK OR APPROVED MATERIAL TYPICAL BENCHING CUT-FILL LOT (DAYLIGHT TRANSITION) PAD GRADE NATURAL GRADE 5s- COMPACTED FILL ****. ^o\v-,o\V^ \^'o*vi^ qp5'MINJMUM •«-: N OVEREXCAVATE 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-1T SETTLEMENT PLATE AND RISER DETAIL 2'X 2'X Mk' STEEL PLATE STANDARD 3/4' PIPE NIPPLE WELDED TO TOP OF PLATE. 3/4" X 5'GALVANIZED PIPE, STANDARD PIPE THREADS TOP AND BOTTOM. EXTENSIONS THREADED ON BOTH ENDS AND ADDED IN 5' INCREMENTS. •3 INCH SCHEDULE 40 PVC PIPE SLEEVE. ADD IN 5'INCREMENTS WITH GLUE JOINTS. FINAL GRADE MAINTAIN 5* CLEARANCE OF HEAVY EQUIPMENT. MECHANICALLY HAND COMPACT IN 2'VERTICAL -T^r LIFTS OR ALTERNATIVE SUITABLE TO AND ACCEPTED BY THE SOILS ENGINEER. MECHANICALLY HAND COMPACT THE INITIAL 5' VERTICAL WITHIN A 5'RADIUS OF PLATE BASE. BOTTOM OF CLEANOUT PROVIDE A MINIMUM T BEDDING OF COMPACTED SAND NOTE: 1. LOCATIONS OF SETTLEMENT PLATES SHOULD BE CLEARLY MARKED AND READILY VISIBLE {RED FLAGGED) TO EQUIPMENT OPERATORS. 2. CONTRACTOR SHOULD MAINTAIN CLEARANCE OF A 5' RADIUS OF PLATE BASE AND WITHIN 5' (VERTICAL) FOR HEAVY EQUIPMENT. RLL WITHIN CLEARANCE AREA SHOULD BE HAND COMPACTED TO PROJECT SPECIFICATIONS OR COMPACTED BY ALTERNATIVE APPROVED BY THE SOILS ENGINEER. 3. AFTER 5'(VERTICAL) OF FILL IS IN PLACE. CONTRACTOR SHOULD MAINTAIN A 51BADIUS EQUIPMENT CLEARANCE FROM RISER. 4. PLACE AND MECHANICALLY HAND COMPACT INITIAL 2' OF FILL PRIOR TO ESTABLISHING THE INITIAL READING. 5. IN THE EVENT OF DAMAGE TO THE SETTLEMENT PLATE OR EXTENSION RESULTING FROM EQUIPMENT OPERATING WITHIN THE SPECIFIED CLEARANCE AREA, CONTRACTOR SHOULD IMMEDIATELY NOTIFY THE SOILS ENGINEER AND SHOULD BE RESPONSIBLE FOR RESTORING THE SETTLEMENT PLATES TO WORKING ORDER. 6. AN ALTERNATE DESIGN AND METHOD OF INSTALLATION MAY BE PROVIDED AT THE DISCRETION OF THE SOILS ENGINEER. PLATE EG-U TYPICAL SURFACE SETTLEMENT MONUMENT FINISH GRADE 3/8-DIAMETER X 6' LENGTH CARRIAGE BOLT OR EQUIVALENT - DIAMETER X 3 1/2* LENGTH HOLE CONCRETE BACKFILL PLATE EG-15 TEST PIT SAFETY DIAGRAM SIDE VIEW m& TEST PIT -ffgjg^ ( NOT TO SCALE ) TOP VIEW 100 FEET ^Tt^^^^T^^^^^^^^^yr APPROXIMATE CENTER OF TESTPfT 5u. 0in FLAG I NOT TO SCALE ) PLATE EB-16 OVERSIZE ROCK DISPOSAL VIEW NORMAL TO SLOPE FACE ^20* MINIMUM CO oo PROPOSED FINISH GRADE )' MINIMUM IE) CO 00 15'MINIMUM IA)<o—~=°00 00 ac* oo (G) 1 MINIMUM (C) ootFJ /^>^ BEDROCK OR APPROVED MATERIAL VIEW PARALLEL TO SLOPE FACE PROPOSED FINISH GRADE 10* MINIMUM IE)H100'MAXIMUM (B^- =OC*=CXPSCX xX> 15' MINIMUM 300 FROM 3' MINIMUM BEDROCK OR APPROVED MATERIAL NOTE: (A) ONE EQUIPMENT WIDTH OR A MINIMUM OF 15 FEET. (B) HEIGHT AND WIDTH MAY VARY DEPENDING ON ROCK SIZE AND TYPE OF EQUIPMENT. LENGTH OF WINDROW SHALL BE NO GREATER THAN 100* MAXIMUM. (C) IF APPROVED BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST. WINDROWS MAY BE PLACED DIRECTLY ON COMPETENT MATERIAL OR BEDROCK PROVIDED ADEQUATE SPACE IS AVAILABLE FOR COMPACTION. - ID) ORIENTATION OF WINDROWS MAY VARY BUT SHOULD BE AS RECOMMENDED BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST. STAGGERING OF WINDROWS IS NOT NECESSARY UNLESS RECOMMENDED. (El CLEAR AREA FOR UTILITY TRENCHES. FOUNDATIONS AND SWIMMING POOLS. IF] ALL FILL OVER AND AROUND ROCK WINDROW SHALL BE COMPACTED TO 90% RELATIVE COMPACTION OR AS RECOMMENDED. (G) AFTER FILL BETWEEN WINDROWS IS PLACED AND COMPACTED WITH THE LIFT OF FILL COVERING WINDROW. WINDROW SHOULD BE PROOF ROLLED WITH A D-9 DOZER OR EQUIVALENT. VIEWS ARE DIAGRAMMATIC ONLY. ROCK SHOULD NOT TOUCH AND VOIDS SHOULD BE COMPLETELY FILLED IN. PLATE RD~ 1 ROCK DISPOSAL PITS VIEWS ARE DIAGRAMMATIC ONLY. ROCK SHOULD NOT TOUCH AND VOIDS SHOULD BE COMPLETELY FILLED IN. FILL LIFTS COMPACTED OVER ROCK AFTER EMBEDMENTi— — I I GRANULAR MATERIAL I j COMPACTED FILL I I I I SIZE OF EXCAVATION TO BE COMMENSURATE WITH ROCK SIZE —I I I I I I I ROCK DISPOSAL LAYERS GRANULAR SOIL TO FILL VOIDS. DENSIRED BY FLOODING ^ . LAYER ONE ROCK HIGH \{ J COMPACTED FILLx i«winr/\ui cu TILL [•^>:P^\"^^N?vX' TV*—<C.-r—-v- PROPOSED FINISH GRADE l\0' MINIMUM OR BELOW LOWEST UTIUT OVERSIZE LAYER PROFILE ALONG LAYER 20 MUM FRtJWxSLOPE FACE CLEAR ZONE 20'MINIMUM LAYER ONE ROCK HIGH PLATE RD-2