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Home My WebLink AboutMS 01-15; THOMPSON SUBDIVISION; PRELIMINARY GEOTECHNICAL EVALUTATION; 2001-06-29PRELIMINARY GEOTECHNICAL EVALUATION 3940 ALDER AVENUE CITY OF CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA FOR MR. DAVID THOMPSON 3940 ALDER AVENUE CARLSBAD, CALIFORNIA 92054 W.O. 3104-A-SC JUNE 299 2001 0 Geotechnical *Geologic * Environmental 5741 Palmer Way • Carlsbad, California 92008 • (760) 438-3155 • FAX (760) 931-0915 June 29, 2001 W.O. 3104-A-SC Mr. David Thompson 3940 Alder Avenue Carlsbad, California 92008 Attention: Mr. David Thompson Subject: Preliminary Geotechnical Evaluation, 3940 Alder Avenue, City of Carlsbad, San Diego County, California Dear Sir: In accordance with your request and authorization, GeoSoils, Inc. (GSI) has performed a geotechnical evaluation of the subject site. The purpose of the study was to evaluate the onsite soils and geologic conditions and their effects on the proposed site development from a geotechnical viewpoint. EXECUTIVE SUMMARY Based on our review of the available data (Appendix A), as well as field exploration, laboratory testing, and geologic and engineering analysis, development of the property appears to be feasible from a geotechnical viewpoint, provided the recommendations presented in the text of this report are properly incorporated into design and construction of the project. The most significant elements of this study are summarized below: All existing topsoil/colluvium is generally loose and potentially compressible, and is not suitable for the support of settlement sensitive improvements. These materials will require removal and recompaction if settlement sensitive improvements are proposed within their influence. Depth of removals are outlined in the conclusions and recommendations section of this report. In general, removals will be on the or f1to2etarossa"majority of the site Laboratory testing indicates the expansion potential of the onsite soils is low. At the present time, soluble sulfate and corrosion testing results were not available. An addendum report presenting those results will be provided when lab testing is complete. Reviewed by: Groundwater was not encountered onsite and is generally not anticipated to affect site development, providing that the recommendations contained in this report are incorporated into final design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities should not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Conventional foundation systems utilizing slab-on-grade may be used onsite. The seismic design parameters presented herein should be considered during project planning and design. The geotechnical design parameters presented herein should be incorporated into project planning, design, and construction by the project structural engineer and architect. 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. 0 Respectfully submitted GeoSoils, Inc. 11Exp.•VI 1-I eobe;rt G ~Cnsman Engineering Geologist, CEG 1934 RGC/ARKTJh Distribution: (4) Addressee Mr. David Thompsom W.O. 31 04-A-SC F1Ie:e:\wp7\3100\3104a.pge Page Two GeoSoils, Inc. TABLE OF CONTENTS SCOPE OF SERVICES . 1 SITE CONDITIONS/PROPOSED DEVELOPMENT ..............................1 FIELD STUDIES ..........................................................3 REGIONAL GEOLOGY . ...................................................3 EARTH MATERIALS ......................................................3 Colluvium/Topsoil (Not mapped) ......................................3 Terrace Deposits (Map Symbol-Qt) ......................................5 GROUNDWATER ............................................. ............5 FAULTING AND REGIONAL SEISMICITY ......................................5 Faulting ................• ...................5 Seismicity ..........................................................6 Seismic Shaking Parameters ...........................................6 Seismic Hazards ....................................................7 LABORATORY TESTING ..................................................8 General ........................................................... 8 - Moisture-Density Relations ..........................................8 Shear Testing ......................................................8 Expansion Potential .................................................8 Corrosion/Sulfate Testing ...............................................9 CONCLUSIONS ..........................................................9 EARTHWORK CONSTRUCTION RECOMMENDATIONS ........................9 General............................................................9 Site Preparation ...................................................9 Removals (Unsuitable Surficial Materials) ...............................9 Fill Placement ......................................................10 Overexcavation ....................................................10 FOUNDATION RECOMMENDATIONS ......................................10 General............................................................10. Preliminary Foundation Design .......................................11 Bearing Value ................................................11 Lateral Pressure ...............................................11 Footing Setbacks -..................................................11 Construction .......................................................12 Low Expansive Soils (Expansion Index 21 to 50) ................... 12 GeoSoils, Inc. CONVENTIONAL RETAINING WALLS .• 13 General..........................................................13 Restrained Walls.................... ..................... ........... 13 Cantilevered Walls ..................................................13 Wall Backfill and Drainage ............................................14 Retaining Wall Footing Transitions ...................................14 Footing Excavation Observation .....................................15 DEVELOPMENT -CRITERIA ................................................15 Landscape Maintenance and Planting .................................15 Additional Site Improvements .........................................16 Trenching........................................................16 Drainage ...........................................................16 Utility Trench Backfill ................................................16 PLAN REVIEW ............................................................17 LIMITATIONS .............................................................17 FIGURES: Figure .1 - Site Location Map ..........................................2 Figure 2 - Boring Location Map ........................................4 ATTACHMENTS: Plate 1 -. Geotechnical Map .................................Rear of Text Appendix A - References ...................................Rear of Text Appendix B - Test Pit Logs ................................... Rear of Text Appendix C- Laboratory Data ...............................Rear of Text Appendix D - General Earthwork and Grading Guidelines ..........Rear of Text Mr. Tom Robertson Table of Contents File:e:/wp7/3000/3058a.pge S Page ii GeoSoils, Inc. PRELIMINARY GEOTECHNICAL EVALUATION 3940 ALDER AVENUE CITY OF CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA SCOPE OF SERVICES The scope of our services has included the following: Review of readily available soils and geologic data (Appendix A), including the previous geologic report for the site, Subsurface exploration consisting of 5 hand auger boring excavations to determine the soil/bedrock profiles, obtain relatively undisturbed .and bulk samples of representative materials, and delineate earth material parameters for the proposed development (Appendix B). - Laboratory testing of representative soil samples collected during our subsurface exploration program (Appendix C). General areal seismicity evaluation. Appropriate engineering and geologic analysis Of data collected and preparation of this report. SITE CONDITIONS/PROPOSED DEVELOPMENT The site consists of a irregular shaped parcel located on the south side of Alder Avenue in Carlsbad, California (Figure 1). The existing site is surrounded by existing housing developments. Site drainage is generally to the southwest. According to a USGS 1968 (photorevised 1975) San Luis Rey Quadrangle map, the subject site is approximately 299 feet above Mean Sea Level (MSL). Vegetation onsite consists of grasses and scattered trees. It is also our understanding that the proposed site development will consist of preparing the pad for the construction of a new residential structure. Cut and fill grading techniques would be utilized to create design grades for the proposed single-family residential structure. It is anticipated that the residential development will consist of a one- or two- story structure with slab-on-grade floors and continuous footings, utilizing wood-frame construction. Building loads are assumed to be typical for this type of relatively light construction. The need for import soils is unknown. It is anticipated that sewage disposal will be tied into the regional system. GeoSoils, Inc. 3-D TopoQuads Copyright 1999 DeLorme \armouth, SIr, ,4)9b Source Data: USGS L ------- ' :Buer av4 'F - 'il F ' 7 - 11 N ''• II Wee -v / WT 162 — Ke mt y We 'h HIgh Seh - Mgnoba SITE / "Ch t Valky Jr HkhRch* k>t / A G A 2AZ / I Ii / 6 /aJ / ç\ / - va Poi / • . VA -- - Agua 357 sSubsta essc - F Wafer -. -77 F Base Map: San Luis Rey Quadrangle, California--San Diego Co., 7.5 Minute Series (Topographic), 1968 (photorevised 1975) by USGS, 1":2000 W.0. GeoQ Us, 3104-A-SC SITE LOCATION MAP 0 2000 4000 Scale Feet Figure 1 FIELD STUDIES Field work conducted during our evaluation of the property consisted of excavating five hand auger borings within the lot to evaluate near surface soil and geologic conditions. The borings were logged by a geologist from our firm. Representative bulk and in-place samples were taken for appropriate laboratory testing. Logs of the borings are presented in Appendix B. The approximate locations of the borings are shown on Plate 1. REGIONAL GEOLOGY The subject property is located within a prominent natural geomorphic province in southwestern California known as the Peninsular Ranges. It is characterized by steep, elongated mountain ranges and valleys that trend northwesterly. The mountain ranges are underlain by basement rocks consisting of pre-Cretaceous metasedimentary rocks, Jurassic metavolcanic rocks, and Cretaceous plutonic rocks of the southern California batholith. In the San Diego region, deposition occurred during the Cretaceous period and Cenozoic era in the continental margin of a forearc basin. Sediments, derived from Cretaceous-age plutonic rocks and Jurassic-age volcanic rocks, were deposited into the narrow, steep, coastal plain and continental margin of the basin. These rocks have been uplifted, eroded and deeply incised. During early Pleistocene time, a broad coastal plain was developed from the deposition of marine terrace deposits. During mid to late Pleistocene time, this plain was uplifted, eroded and incised. Alluvial deposits have since filled the lower valleys, and young marine sediments are currently being deposited/eroded within coastal and beach areas. EARTH MATERIALS Earth materials encountered on the site are Shown on Figure 2. The materials consist of colluvium and terrace deposits. Topsoll/Colluvlum (Not Mapped) Topsoil/colluvium onsite was found to generally consist of a brown, dry, loose, silty sand. Thickness of the material is approximately 1 to 2 feet. Topsoil/colluvium at the subject site is considered potentially compressible in its present state. Accordingly, these soils are considered unsuitable for support of additional fill and/or settlement sensitive improvements in their existing state. Mr. David Thompson W.O. 31 04-A-SC 3940 Alder Avenue, Carlsbad June 29, 2001 F1Ie:e:\wp7\3100\3104a.pge Page 3 GeoSoils, Inc. Terrace Deposits (Map Symbol - Qt) The Quaternary-age terrace deposits underlie the entire site at depth. As encountered, the terrace deposits generally consist of reddish brown, damp, silty sandy to clayey silty sand, and is medium dense to dense with depth. Due to the relatively soft and weathered condition of the upper ±1 foot, these materials should be removed, moisture conditioned, and recompacted and/or processed in place, should settlement-sensitive improvements be proposed. This unit typically has a low to medium expansion potential. GROUNDWATER Groundwater was not encountered onsite and is generally not anticipated to significantly affect site development, providing that 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 permebilities should not be precluded from occurring in the future (i.e. post grading) due to site irrigation, rainfall, poor drainage conditions, or damaged utilities. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. FAULTING AND REGIONAL SEISMICITY Faulting The site is situated in aregion of active as well as potentially-active faults. Our review indicates that there are no known active faults crossing the Site within the areas proposed for development (Jennings, 1994), and the site is not within an Earthquake Fault Zone (Hart and Bryant, 1997). There are a number of faults in the southern California area that are considered active and would have an effect on the site in the form of ground shaking, should they be the source of an earthquake (Figure 2). These faults include—but are not limited to—the San Andrëas fault, the San Jacinto fault, the Elsinore fault, the Coronado Bank fault zone, and the Newport-Inglewood - Rose Canyon fault zone. The possibility of ground acceleration or shaking at the site may be considered as approximately similar to the southern California region as a whole. The following table lists the major faults andfault zones in southern California that could have a significant effect on the site should they experience significant activity. Mr. David Thompson - W.O. 3104-A-SC 3940 Alder Avenue, Carlsbad June 29, 2001 File:e:\wp73100\3104a.pge Page 5 GeoSoils, Inc. ABBREVIATED FAULT NAME APPROXIMATE DISTANCE MILES (KM) Coronado Bank-Agua Blanca 22 (35) Elsinore 23 (38) La Naàión 24 (39) Newport-Inglewood-Offshore 9 (14) Rose Canyon 5 (9) San Diego Trough-Bahia Sol. 31(50) Seismicity The acceleration-attenuation relations of Joyner and Boore (1982), Campbell and Bozorgnia (1994), and Sadigh and others (1987) have been incorpprated into EQFAULT (Blake, 1997). For this study, peak horizontal ground accelerations anticipated at the site were determined based on the random mean and mean plus 1 sigma attenuation curves developed by Joyner and Boore (1982), Campbell and Bozorgnia (1994), and Sadigh and others (1989). These acceleration-attenuation relations have been incorporated in EQFAULT, a computer program by Thomas F. Blake (1997), which performs deterministic seismic hazard analyses using up to 150 digitized California faults as earthquake sources. The program estimates the closest distance between each fault and a user-specified file. 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 the upper bound 'maximum credible' and "maximum probable" earthquakes on that fault. Site acceleration, as a percentage of the acceleration of gravity (g), is computed by any of the 14 user-selected acceleration-attenuation relations that are contained in EQFAULT. Based on the above, peak horizontal ground accelerations from an upper bound (maximum credible) earthquake may be on the order of 0.48 g to 0.69 g, and maximum probable event may be on the order of 0.32 g to 0.39 g, assuming upper bound (maximum credible) and maximum probable event of a magnitude about 6.9, on the Rose Canyon fault zone, located approximately 6 miles from the subject site. Seismic Shaking Parameters. Based on the site conditions, Chapter 16 of the Uniform Building Code (International Conference of Building Officials, 1997), the following seismic parameters are provided. Mr. David Thompson W.O. 3104-A-SC 3940 Alder Avenue, Carlsbad June 29, 2001 F1Ie:e:\wp731OO'.31O4a.pge Page 6 GeoSoi is, Inc. Seismic zone (per Figure 16.2*) . 4 Seismic Zone Factor (per Table 16.1*) . 0.40 Soil Profile Type (per Table 16-J*) SD Seismic Coefficient C. (per Table 16-Q*) 0.44 Na Seismic Coefficient C (per Table 16-R*) 0.64 N' Near Source Factor N1 (per Table 16.S*) .1.0 Near Source Factor N (per Table 16.1*) 1.05 Seismic Source Type (per Table 16-U*) . B Distance to Seismic Source 5.3 mi. (8.5 km) Upper Bound Earthquake . MW 6.9 * Figure and table references from Chapter 16 of the Uniform Building Code (1997). Seismic Hazards The following list includes other seismic related hazards that have been considered during our evaluation of the site. The hazards listed are considered negligible and/or completely mitigated as a result of site location, soil characteristics and typical site development procedures: Liquefaction Tsunami Dynamic Settlement Surface Fault Rupture Ground Lurching or Shallow Ground Rupture 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. . Mr. David Thompson W.O. 3104-A-SC 3940 Alder Avenue, Carlsbad June 29, 2001 F1Ie:e:\wp7\3100\3104a.pge Page 7 GeoSoils, Inc. 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. Moisture-Density Relations The laboratory maximum dry density and optimum moisture content for representative site soils was determined according to test method ASTM D-1 557. A modified proctor-of 120.0 pounds per cubic foot (pcf), with an optimum moisture content of .11.5 percent was determined for a composite sample of terrace and existing fill materials. Shear Teèting Shear testing was performed on a representative, undisturbed and remolded sample of site soil in general accordance with ASTM test method D-3080 in a Direct Shear Machine of the strain control type. Shear test results are presented in the following table: Sample , los I 1P (rAmnideth 232 33 215 .33 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. LOCATIONV EXPANSION INDEX Fyzf EXPANSION POTENTIALW I B-i, Silty Sand 0 Very Low Mr. David Thompson W.O. 3104-A-SC 3940 Alder Avenue, Carlsbad . June 29, 2001 FiIe:e:\wp7\310031 04a.pge . Page 8 GeoSoils, Inc. Corrosion/Sulfate Testing A typical sample of the site material was analyzed for corrosion/soluble sulfate potential. The testing included determination of pH, soluble sulfates, and saturated resistivity. Test results are presented in Appendix C as Plate C-i. CONCLUSIONS Based upon our site reconnaissance, test results, and review of the previous report, it is our opinion that the subject site appears suitable for the proposed residential development. The following recommendations should be incorporated into the construction details. EARTHWORK CONSTRUCTION RECOMMENDATIONS General All grading should conform to the guidelines presented in Appendix Chapter A33 of the Uniform Building Code, the requirements of the City of Carlsbad, and the Grading Guidelines presented in Appendix D, except where specifically superseded in the text of this report. Prior to grading, a GSI representative should be present at the preconstruction meeting to provide additional grading guidelines, if needed, and review the earthwork schedule. During earthwork construction all site preparation and the general grading procedures of the contractor should be observed and the fill selectively tested by a representative(s) of GSI. If unusual or unexpected conditions are exposed in the field, they should be reviewed by this office and if warranted, modified and/or additional recommendations will be offered. All applicable requirements of local and national construction and general industry safety orders, the Occupational Safety and Health Act, and the Construction Safety Act should be met. Site Preparation Debris, vegetation and other deleterious material should be removed from the building area prior to the start of grading. Sloping areas to receive fill should be properly benched in accordance with current industry standards of practice and guidelines specified in the Uniform Building Code. Removals (Unsuitable Surficlal Materials) Due to the relatively loose/soft condition of topsoil/colluvium and weathered terrace deposits, these materials should be removed and recompacted in areas proposed for Mr. David Thompson W.O. 3104-A-SC 3940 Alder Avenue, Carlsbad S June 29, 2001 F11e:e:\wp7'31003104a.pge Page 9 GeoSoils, Inc. settlement sensitive structures, or areas to receive compacted fill. At this time, removal depths on the order of ±1 to ±2 feet should be anticipated; however, locally deeper removals may. be necessary. 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. Once removals are completed, the exposed bottom should be reprocessed and compacted. Fill Placement Subsequent to ground preparation, onsite soils may be placed in thin (6±inch) lifts, cleaned of vegetation and debris, brought to a least optimum moisture content, and compacted to achieve a minimum relative compaction of 90 percent. If soil importation is planned, a sample of the soil import should be evaluated by this office prior to importing, in order to assure compatibility with the onsite site soils and the recommendations presented in this report. Import soils (if any) for a fill cap should be low expansive (E.l. less than 50). The use of subdrains at the bottom of the fill cap may be necessary, and subsequently recommended based on compatibility with onsite soils. Overexcavatlon In order to provide for the uniform support of the planned structure, a minimum 3-foot thick fill blanket is recommended for the graded pad. Any cut portion of the pad for the residence should be overexcavated a minimum 3 feet below finish pad grade. Areas with planned fills less than 3 feet should be overexcavated in order to provide the minimum fill thickness. FOUNDATION RECOMMENDATIONS General In the event that the information concerning the proposed development plan is not correct, or any changes in the design; location or loading conditions of the proposed structure are made, the, conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or approved in writing by this office. It is our understanding that slab-on-grade construction is desired for the proposed development. The information and recommendations presented in this section are not meant to supersede design by the project structural engineer. Upon request, GSI could provide additional input/consultation regarding soil parameters, as related to foundation design. Mr. David Thompson W.O. 3104-A-SC 3940 Alder Avenue, Carlsbad June 29, 2001 Fde:e:\wp7\31 OO1 04ap9e Page 10 GeoSoils, Inc. Preliminary Foundation Design Our review, field work, and laboratory testing indicates that onsite soils have a very low expansion potential. Preliminary recommendations for foundation design and construction are presented below. Final foundation recommendations should be provided at the conclusion of grading, and based on laboratory testing of fill materials exposed at finish grade. Bearing Value The foundation systems should be designed and constructed in accordance with guidelines presented in the latest edition of the Uniform Building Code. An allowable bearing value of 1500 pounds per square foot may be used for the design of continuous footings at least 12 inches wide and 12 inches deep, and column footings at least 24 inches square and 18 inches deep, connected by a grade beam in at least one direction. This value may be increased by 20 percent for each additional 12 inches in depth to a maximum of 2500 pounds per square foot. No increase.in bearing value is recommended for increased footing width. Lateral Pressure For lateral sliding resistance, a 0.35 coefficient of friction may be utilized for a concrete to soil contact when multiplied by the dead load. Passive earth pressure may be computed as an equivalent fluid having a density of 250 pounds per cubic foot with a maximum earth pressure of 2500 pounds per square foot. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. Footing Setbacks All footings should maintain a minimum 7-foot horizontal setback from the base of the footing to any descending slope. This distance is measured from the footing face at the bearing elevation. Footings should maintain a minimum horizontal setback of H/3 (H=siope height) from the base of the footing to the descending slope face and no less than 7 feet, nor need to be greater than 40 feet. Footings adjacent to unlined drainage swaies should be deepened to a minimum of 6 inches below the invert of the adjacent unlined swale. Footings for structures adjacent to retaining walls should be deepened so as to extend below a 1:1 projection from the heel of the wall. Alternatively, wails may be designed to accommodate structural loads from buildings or appurtenances as described in the retaining wail section of this report. Mr. David Thompson W.O. 3104-A-SC 3940 Alder Avenue, Carlsbad June 29, 2001 FIIe:e:\wp7\3100\3104a.pge Page 11 GeoSoils, Inc. Construction The following foundation construction recommendations are presented as a minimum criteria from a soils engineering standpoint. generally-inthe -very- low - (expans]ñdio to 20). irijading of the site, we recommend-that any, expanshiiiterial encountered should not be placed within 3 feet of finish grade, if feasible. Therefore, it is anticipated that the finish grade materials will have a very low expansion potential. Recommendations by the project's design-structural engineer or architect, which may exceed the soils engineers recommendations, should take precedence over the following minimum requirements. Final foundation design will be provided based on the expansion potential of the near surface soils encountered during grading. Very Low Expansive Soils (Expansion index 0 to 20) Exterior and interior footings should be founded at minimum depths of 12 and 18 inches for one or two-story floor loads, respectively, below the lowest adjacent surface. Isolated column and panel pads or wall footings, should be founded at a minimum depth of 18 inches and connected in one direction by a grade beam. All footings should be reinforced with a minimum of two No. 4 reinforcing bars, one placed near the top and one placed near the bottom of the footing, and in accordance with the recommendations width per UBC. A grade beam, reinforced as above, and at least 12 inches wide should beprovided across large (e.g., garage or parking area) entrances. The base of the grade beam should be at the same elevation as the bottom of adjoining footings. Concrete slabs should be underlain by a minimum of 2 inches of washed sand. Where moisture condensation is undesirable, conàrete slabs should be underlain with a vapor barrier consisting of a minimum 6 mu, polyvinyl-chloride or equivalent membrane, with all laps sealed. This membrane should be placed on acceptable pad grade materials with a minimum 2-inch thickness of sand should be placed over the visqueen to aid in uniform concrete curing. if proven by testing (i.e., sand equivalent greater than 30 and less than ¼ inch in any size dimension), some of the native sands could be utilized. Concrete slabs, including garage areas, should be minimally reinforced with No. 3 reinforcement bars placed on 18-1 * nch centers, each way. All slab reinforcement should be supported and positined near the vertical midpoint of the slab. "Hooking" of reinforcement is not an acceptable method of positioning the reinforcement. Mr. David Thompson W.O. 3104-A-SC 3940 Alder Avenue, Carlsbad June 29, 2001 FiIe:e:\wp7\3100\3104a.pge Page 12 GeoSoils, Inc. Garage slabs should be poured separately from adjacent 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. A minimum slab thickness of 4 inches is recommended. The design engineer should determine the actual thickness of the slabs based on anticipated loadings and use. Premoistening is recommended for these soils conditions, with the moisture content of the subgrade soils equal to or greater than the optimum moisture content to a depth of 12 inches prior to poyring slabs and prior to placing visqueen or reinforcement. In design of any additional concrete, flatwork, pools or walls, the potential for differential settlement of the soils should be considered. CONVENTIONAL RETAINING WALLS General The design parameters provided below assume that either native soil or non-expansive select material (such as gravel) is used to backfill any retaining walls. If high to very highly expansive soils are used to backfill the proposed walls, increased active and at-rest earth pressures will need to be utilized for retaining wall design, and may be provided upon request. Building walls, below grade, should be water-proofed or damp-proofed, depending on the degree of moisture protection desired. The foundation system for the proposed retaining walls should be designed in accordance with the recommendations presented in the preceding sections of this report; as appropriate. Footings should be embedded a minimum of 18 inches below adjacent grade (excluding landscape layer, 6 inches). There should be no increase in bearing for footing width. Restrained Walls Any retaining walls that will be restrained prior to placing and compacting backfill material or that have re-entrant or male corners, should be designed for an at-rest equivalent fluid pressure (EFP) of 65 pounds per cubic foot (pcf), plus any applicable surcharge loading. For areas of male or re-entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall laterally from the corner. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 15 feet high. Active earth pressure may be used for retaining wall design, provided the top of the Mr. David Thompson W.O. 31 04-A-SC 3940 Alder Avenue, Carlsbad June 29, 2001 FiIe:e:\wp7'3100\31 04a.pge Page 13 GeoSoils, Inc. wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. These do not include other superimposed loading conditions such as traffic, structures, hydrostatic pressures, seismic events or adverse geologic conditions. When wall configurations are finalized, the appropriate loading conditions for superimposed loads can be provided upon request. SURFACE SLOPE OF. ' ' EQUIVALENT .' '•" SELECT' RETAINED MATERIAL . FLUID WEIGHT : . MATERIAL HORIZONTAL TO VERTICAL P.C.F. (Native soil)' P.C.F. (Gravel) Level 40 ' 1 35 2tol 55 45 The equivalent fluid density should be increased to 65 pounds per cubic foot for level backfill at the angle point of the wall (corner or male re-entrant) and extended a minimum lateral distance of 2H (two times the wall height) on either side of the corner. Wall Backfill and Drainage The above criteria assumes that very low expansive soils are used as backfill, and that hydrostatic pressures are not allowed to build up behind the wall. Positive drainage must be provided behind all retaining walls in the form of perforated pipe placed within gravel wrapped in geofabric and outlets. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Backdrains should consist of a 4-inch diameter perforated PVC or ABS pipe encased in either Class 2 permeable filter material or 1/2 to 3/4-inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent). The filter material should extend a minimum of one horizontal foot behind the base of the walls and upward at least one foot. Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no more greater than 100± feet apart. The use of weep holes in walls higher than 2 feet should not be considered. The surface of the backfill should be sealed by pavement or the top 18 inches compacted with relatively impermeable soil. Proper surface drainage should also be provided. Consideration should be given to applying a water- proof membrane to all retaining structures. The use of a waterstop should be considered for all concrete and masonry joints. Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Wall footings may transition from competent terrace deposits to fill. If this condition is present the civil designer may specify either: Mr. David Thompson W.O. 3104-A-SC 3940 Alder Avenue, Carlsbad June 29, 2001 F11e:e:\wp7'3100\3104a.pge Page 14 GeoSoils, Inc. a) If transitions from terrace to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should perform a minimum 2-foot overexcavation for a distance of two times the height of the wall and increase overexcavation until such transition is between 45 and 90 degrees to the wall alignment. Increase of The amount of reinforcing steel and wall detailing (Le., expansion joints or crack control joints) such that an angular distortion of 1/360 for a distance of 2H (where H=wall height in feet) on either side of the transition may be accommodated. Expansion joints should be sealed with a flexible, non-shrink grout. Embed the footings entirely into a homogeneous fill. Footing Excavation Observation All footing excavations for walls and appurtenant structures should be observed by the geotechnical consultant to evaluate the anticipated near surface conditions prior to the placement of steel or concrete. Based on the conditions encountered during the observations of the footing excavation, supplemental recommendations may be offered, as appropriate. DEVELOPMENT CRITERIA Landscape Maintenance and Planting Water has been shown to weaken the inherent strength of soil and slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from graded slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Overwatering should be avoided. Graded slopes constructed within and 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. Plants selected for landscaping should be light weight, deep rooted types which require little water and are capable of surviving the prevailing climate. Compaction to the face of fill slopes would tend to minimize short term erosion until vegetation is established. In order to minimize erosion on a slope face, an erosion control fabric (i.e. jute matting) may be considered. From a geotechnical standpoint leaching is not recommended for establishing landscaping. If the surface soils area processed for the purpose of adding amendments they should be recompacted to 90 percent relative compaction. Mr. David Thompson W.O. 3104-A-SC 3940 Alder Avenue, Carlsbad • June 29, 2001 FiIe:e:\wp731003104a.pge Page 15 GeoSoils, Inc. Additional Site Improvements Recommendations for additional grading, exterior concrete flatwork design and construction, including driveways, can be provided upon request. If in the future, any additional improvements are planned for the site, recommendations concerning the geological or geotechnical aspects of design and construction of said improvements could be provided upon request. Trenching All footing trench excavations for structures and walls should be observed and approved by a representative of this office prior to placing reinforcement. 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. All excavations should be observed by one of our representatives and conform to CAL-OSHA and local safety codes. GSI does not consult in the area of safety engineers. In addition, the potential for encountering hard spots during footing and utility trench excavations should be anticipated. If these concretions are encountered within the proposed footing trench, they should be removed, which could produce larger excavated areas within the footing or utilit/ trenches. Drainage Positive site drainage should be 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. Pad drainage should be directed toward the street or other approved area. Roof gutters and down spouts should be considered to control roof drainage. Down spouts should outlet a minimum of 5 feet from the proposed structure or into a subsurface drainage system. 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. Utility Trench Backfill 1.* All utility trench backfill in structural areas, slopes, and beneath hardscape features should be brought to near optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard. Flooding/jetting is not recommended for the site soil materials. As an alternative, imported sandy material with an S.E. of 30 or greater, may be flooded/jetted in shallow (12±inch or less) under-slab interior trenches, only. Mr. David Thompson W.O. 3104-A-SC 3940 Alder Avenue, Carlsbad June 29, 2001 FiIe:e:\wp7'3100104a.pge Page 16 GeoSoils, Inc. Sand backfill, unless trench excavation material, should not be allowed in exterior trenches adjacent to and within an area extending below a 1:1 plane projected from the outside bottom edge of the footing. All trench excavations should minimally conform to CAL-OSHA and local safety codes. Soils .generated from utility trench excavations to be used onsite should be compacted to 90 percent minimum relative compaction. This material must not alter positive drainage patterns that direct drainage away from the structural area and towards the street. PLAN REVIEW Final site development and foundation plans should be submitted to this office for review and comment, as the plans become available, for the purpose of minimizing any misunderstandings between the plans and recommendations presented herein. In addition, foundation excavations and any additional earthwork construction performed on the site should be observed and tested by this office. If conditions are found to differ substantially from those stated, appropriate recommendations would be offered at that time. LIMITATIONS The materials encountered. on the project site and utilized in our study 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. GSI assumes no responsibility or liability for work, testing or recommendations performed or provided by others. The scope of work was performed within the limits of a budget. Inasmuch as our study is based upon the site materials observed, selective laboratory testing and engineering analysis, the conclusion 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. Mr. David Thompson W.O. 3104-A-SC 3940 Alder Avenue, Carlébad June 29, 2001 File:e:\wp7\3100\3104a.pge Page 17 GeoSoils, Inc. LEGEND 0 t Quaternary terrace d6p081t8 C B-5 Approximate location of test boring Driveway Alder Avenue \ I roes and shrubs Existing house Iceplant Stairway Trees and shrubs at CB-2 CB-4 Retaining wall 4)B-1 4)- Iceplant ot. I at at • •• • LOS ANGELES CO. g RIVERSIDE CO. ORANGE CO. '--.' '--' SAN DIEGO CO. GEOTECHNICAL MAP Plate 1 NOT A SURVEYED MAP 1w.o. 3104-A-SC DATE 6/01 SCALE flOfl APPENDIX A REFERENCES APPENDIX A REFERENCES Benton Engineering, Inc., 1970, Final Compaction Report, La Costa South Unit 7, August 10, 1970, Project # 69-12-81). Blake, Thomas F., 1997, EQFAULT computer program for the deterministic prediction of horizontal accelerations from digitized California faults. Campbell, K.W. and Bozorgnia, V., 1994, Near-source attenuation of peak horizontal acceleration from worldwide accelrograms recorded from 1957 to 1993; Proceedings, Fifth U.S. National Conference on Earthquake Engineering, volume Ill, Earthquake Engineering Research Institute, pp 292-293. Hart, E.W. and Bryant, W.A. 1997, Fault-rupture Hazard Zones in California, Alquist-Priolo Earthquake Fault Zoning act with Index to Earthquake Fault Maps; California Division of Mines and Geology Special Publication 42. International Conference of Building Officials, 1997, Uniform building code: Whittier, California, vol. 1, 2, and 3. Jennings, C.W., 1994, Fault activity map of California and adjacent areas: California Division of Mines and Geology,*Map Sheet No. 6, scale 1:750,000. Joyner, W.B., and Boore, D.M., 1982, Estimation of response-spectral values as functions of magnitude, distance and site conditions, in eds., Johnson, J.A., Campbell, K.W., and Blake, T.F., AEG short course, seismic hazard analysis, dated June 18, 1994. Petersen, Mark D., Bryant, W.A., and Cramer, C.H., 1996, Interim table of fault parameters used by the California Division of Mines and Geology to compile the probabilistic seismic hazard maps of California. Sadigh,K., Egan, J., and Youngs, R., 1987, Predictive ground motion equations reported in Joyner, W.B., and Boore, D.M., 1988, "Measurement, characterization, and prediction of strong ground motion', in Earthquake Engineering and Soil Dynamics II, Recent Advances in Ground Motion Evaluation, Von Thun, J.L., ed.: American Society of Civil Engineers Geotechnical Special Publication No. 20, pp. 43-102. Tan, S.S., and Kennedy, Michael P., 1996, Geologic maps of the northwestern part of San Diego County, California: California Division of Mines and Geology, Open File Report 96-02. GeoSoils, Inc. APPENDIX B BORING LOGS BORING LOG GeoSoils, Inc. W.O. 3104-A-SC PROJECT: David Thompson BORING B-i SHEET 10F David Thompson DATE EXCAVATED [5-29-011 'S Sample x SAMPLE METHOD: HAND ANGER Sd 'S 9- C Standard Penetration Test 4- 0 9-• 'S L. 4- Water Seepage into hole u — C 3 Undisturbed, Ring Sample Z ow 5 0 4- L 4- Ad —.D 3 C#LJ3 IL 0 3 5. —L 0 05 31 4. F S C 3 — 3 L o 4- Description of Material &4 0 E (I) - - - 0-1' TOPSOIL/COLLUVIUM; SILTY SAND, brown, moist, • . \loose; roots and rootlets.SM - 1-1 .5'TERRACE DEPOSITS; SILTY SAND, reddish brown, • damp, medium dense. • 1.5-2' - 'Clayey silty sandy reddish brown, damp, medium dense - Practical Refusal @2' .) 5. - No groundwater encountered Backfilled 5/29/01 10- 15- 20 25 - , GeoSoils Inc. David Thompson PLA TE B-i BORING LOG GeoSoils, Inc. WO. 3104-A-SC PROJECT: David Thompson BORING B-2 SHEET 1 O David Thompson DATE EXCAVATED 15-29-01.J Sample SAMPLE METHOD: HANDANGER C 4- Standard Penetration Test 0 I.. 4 •f-_ a• L 4- I - C ' Undisturbed, Ring Sample Water Seepage into hole a o 4- 9 •-•o 3 V) J0 • a 0. - VL 0 QE - I- C - In L 0 Description of Material 4- DC 0 E In - - 0-1' TOPSOIL/COLLUVIUM; SILTY SAND, brown, moist, \loose;rootsandrootlets. SM - 1-3' TERRACE DEPOSITS; Clayey silty sand, reddish brown, - (damp,,medium dense to dense with depth - Practical Refusal @3' ) - • No groundwater encountered Backfilled 5/29/01 5. 10 15 20 25- GeoSoils, Inc. David Thompson PLATE B-2 BORING LOG GeoSoils, Inc. PROJECT: David Thompson David Thompson Sample I 4- I.. 4 4-. a ID I.- \ - Cl'. L we a o D 4- 4- .-.0 3. a IL -L 0 U :a" - a - u 0 o D9- V) 0 E 5 w.o. 3104-A-SC BORING B-3 SHEET.J_OF .j... DATE EXCAVATED , _5-29-01) SAMPLE METHOD: HAND ANGER Standard Penetration Test 4- . Water Seepage into hole Undisturbed, Ring Sample Description of Material - 0-1' TOPSOIL/COLLUVIUM;SILTY SAND, brown, dry to - - damp, loose; roots and roolets. 1-2.5' TERRACE DEPOSITS; Clayey silty sand, reddish brown, damp, medium dense to dense with depth. Practical Refusal @2.51 No groundwater encountered, Backfilled 5/29/01 David Thompson . Geo Soils, Inc. PLATE_B-3 BORING LOG GeoSoils, Inc. w.o. 3104-A-SC PROJECT: David Thompson BORING B-4 SHEET 1 OF David Thompson DATE EXCA VA TED .5-29-01 Sample 4- 4- II. I.. 4- 4- I V 4- a -.uI 3 tn•.a CL IL —ILI 0 (JE 3" a lcI - 03 o P4-1 D(p 0 SAMPLE METHOD: HAND ANGER 9' .a 9% % C o Standard Penetration Test S L - 4- Water Seepage into hole 4- L Undisturbed, Ring Sample a - o E 4- Description of Material ij- i . Jr ,ILIJLLuyIuIvI; OIL i i EIAND, orown, ary, loose; - - rpts and rootlets. 1-3' TERRACE DEPOSITS: Clayey silty sand reddish brown, brown, damp, medium dense to dense with depth. Practical (Refusal @3') No groundwater encountered' Backfilled 5/29/01 I 10- I 15-1 I 25-I David Thompson GeoSoils, Inc. PITE B-4 BORING LOG GeoSoils, Inc. W.O. 3104-A-SC PROJECT: David Thompson BORING B5 SHEET 1 O David Thompson. DA TE EXCA VA TED 5-29-01) - Sample - SAMPLE METHOD: HAND ANGER • - - Standard Penetration Test • Water Seepage into hole ; Undisturbed, Ring Sample IL 13 L 0 IL Description of Material - - 0-1' TOPSOIL/COLLUVIUM; SILTY SAND, brown, dry, loose; roots and rootlets. SM - 12.5' TERRACE DEPOSITS; Clayey silty sand, reddish brawn, 'damp, medium dense to dense withdepth. • - Practical Refusal @2.5'0 . No groundwater encountered • ' Backfilled 5/29/01 I 5-1 I 10-1 I 15-i I 20-I I 25-1 I I I I I I I I David Thompson GeoSoils, Inc. • PLATE B-5 APPENDIX C LABORATORY DATA M. J. Schiff & Associates, Inc. Consulting Corrosion Engineers - Since 1959 1308 Monte Vista Avenue, Suite 6 Upland, CA 91786-8224 S 0 Phone: 909/931-1360 Table 1- Laboratory Tests on Soil Samples 3104-A-SC Your #3104-A-SC, MJS&A #01-0465LAB 5-Jun-01 Sample ID B-i @ 0-2.5' SEW Resistivity Units as-received ohm-cm 320,000 saturated ohm-cm 6,000 pH 6.5 Electrical Conductivity mS/cm 0.08 Chemical Analyses • Cations calcium Ca2' mg/kg 44 magnesium .Mg2 mg/kg 12 sodium Na1+ mg/kg ND Anions carbonate C032 . mg/kg ND bicarbonate HCO3 mg/kg 43 chloride Cl'-.mg/kg 18 sulfate SO42 mg/kg ND Other Tests ammonium NH4'+ mg/kg na nitrate NO3'_ Mg/kg na II1[ qual iF. Redox III' IF: Electrical conductivity in millisiemens/cm and chemical analysis were made on a 1:5 soil-to-water extract. mg/kg = milligrams per kilogram (parts per million) of dry soil. Redox = oxidation-reduction potential in millivolts ND = not detected • 0 • 0 na = not analyzed • S • • Page lofi • Plate C-I GeoSoils, Inc. APPENDIX D GENERAL EARTHWORK AND GRADING GUIDELINES GENERAL EARTHWORK AND GRADING GUIDELINES General These guidelines present general procedures and requirements for earthwork and grading as shown on the approved grading plans, including preparation of areas to filled, placement of fill, installation of subdrains and excavations. The recommendations contained in the geotechnical report are part of the earthwork and grading guidelines and would supersede 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 dunng 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-1 557-78. Random field compaction tests should be performed in accordance with test method ASTM designation 0-1556-82, 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 GeoSoils, Inc. would vary depending on the soil conditions and the size of the project. The location and frequency of testing would be at the discretion of the geotechnical consultant. Contractor's Responsibility All clearing, site preparation, and earthwork performed on the project should be conducted by the contractor, with observation by geotechnical consultants and staged approval by the governing agencies, as applicable. It is the contractor's responsibility to prepare the ground surface to receive the fill, to the satisfaction of the soil engineer, and to place, spread, moisture condition, mix and compact the fill in accordance with the recommendations of the soil engineer. The contractor should also remove all major non- earth material considered unsatisfactory by the soil engineer. It is the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the earthwork in accordance with applicable grading guidelines, codes or agency ordinances, and approved grading plans. Sufficient watering apparatus and compaction equipment should be provided by the contractor with due consideration for the fill material, rate of placement, and climatic conditions. If, in the opinion of the geotechnical consultant, unsatisfactory conditions such as questionable weather, excessive oversized rock, or deleterious material, insufficient support equipment, etc., are resulting in a quality of work that is not acceptable, the consultant will inform the contractor, and the contractor is expected to rectify the conditions, and if necessary, stop work until conditions are satisfactory. During construction, the contractor shall properly grade all surfaces to maintain good drainage and prevent ponding of water. The contractor shall take remedial measures to control surface water and to prevent erosion of graded areas until such time as permanent drainage and erosion control measures have been installed. SITE PREPARATION All major vegetation, including brush, trees, thiôk 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 Mr. David Thompson S Appendix RI9:e:\wp7\31003104a.pge Page 2 GeoSoils, Inc. 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 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 1/2 the height of the slope. Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable material. Benching may be used to remove unsuitable materials, although it is understood that the vertical height of the bench may exceed 4 feet. Pre-stripping may be considered for unsuitable materials in excess of 4 feet in thickness. All areas to receive fill, including processed areas, removal areas, and the toe of fill benches should be observed and approved by the soil engineer and/or engineering geologist prior to placement of fill. Fills may then be properly placed and compacted until design grades (elevations) are attained.. COMPACTED FILLS Any earth materials imported or excavated on the property may be utilized in the fill provided that each material has been determined to be suitable by the soil engineer. These materials should .be free of roots, tree branches, other organic matter or other deleterious materials. All unsuitable materials should be removed from the fill as directed Mr. David Thompson Appendix FiIe:e:\wp7\31 00\31 04a.pge Page 3 GeoSoils, Inc. by the soil engineer. Soils of poor gradation, undesirable expansion potential,' or substandard strength characteristics may be designated by the consultant as unsuitable and may require blending with other soils to serve as a satisfactory fill material. Fill materials derived from benching operations 'should be dispersed throughout the fill area and blended with other bedrock derived material. Benching operations should not result in the benched material being placed only within a single equipment width away from the fill/bedrock contact. Oversized materials defined as rock or other irreducible materials with a maximum dimension greater than 12 inches should not be buried or placed in fills unless the location of materials and disposal methods are specifically approved by the soil engineer. Oversized material should be taken off-site or placed in accordance with recommendations of the soil engineer in areas designated as suitable for rock disposal. Oversized material should not be placed within 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-1 557-78, or as otherwise recommended by the soil engineer. Compaction equipment should be adequately sized and should be specifically designed for soil compaction or of proven reliability to efficiently achieve the specified degree of compaction. Mr. David Thompson Appendix F11e:e:\wp7't31 00\31 04a.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: 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. 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. 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. Where testing indicates less than adequate compaction, the contractor will be responsible to rip, water, mix and re-compact the slope material as necessary to achieve compaction. Additional testing should be performed to verify compaction. Mr. David Thompson Appendix File:e:\wp710031 04a.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. SUBDRAIN INSTALLATION Subdrains should be installed in approved ground in accordance with the approximate alignment and details indicated by the geotechnical consultant. Subdrain locations or materials should not be changed or modified without approval of the geotechnical consultant. The soil engineer and/or engineering geologist may recommend and direct changes in subdrain line, grade and drain material in the field, pending exposed conditions. The location of constructed subdrains should be recorded by the project civil engineer.. EXCAVATIONS Excavations and cut slopes should be examined during grading by the engineering geologist. If directed by the engineering geologist, further excavations or overexcavation and re-filling of cut areas should be performed and/or remedial grading of cut slopes should be performed. When fill over cut slopes are to be graded, unless otherwise approved, the cut portion of the slope should be observed by the engineering geologist prior to placement of materials for construction of the fill portion of the slope. The engineering geologist should observe all cut slopes and should be notified by the contractor when cut slopes are started. -' If, during the course of grading, unforeseen adverse or potential adverse geologic conditions are encountered, the engineering geologist and soil engineer should investigate, evaluate and make recommendations to treat these problems. The need for cut slope buttressing or stabilizing should be based on in-grading evaluation by-the engineering geologist, whether anticipated or not. Unless otherwise specified in soil and geological reports, no cut slopes should be excavated higher or steeper than that allowed by the ordinances of controlling governmental agencies. Additionally, short-term stability of temporary cut slopes is the contractors responsibility. . Erosion control and drainage devices should be designed by the project civil engineer and should be constructed in compliance with the ordinances of the controlling governmental agencies, and/or in accordance with the recommendations of the soil engineer or engineering geologist.. Mr. David Thompson S Appendix RIe:e:\wp7'3100\31 04a.pge S 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 for the safety of field personnel on grading and construction projects: Safety Meetings: GSI field personnel are directed to attend contractors regularly scheduled and documented safety meetings. Safety Vests: Safety vests are provided for and are to be worn by GSI personnel at all times When they are working in the field. Safety Flags: Two safety flags are provided to GSI field technicians; one is to be affixed to the vehicle when on site, the other is to be placed atop the spoil pile on all test pits. Mr. David Thompson Appendix F1Ie:e:\wpl\3100\3104a.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 representative will eventually be contacted in an effort to effect a solution. However, in the Mr. David Thompson Appendix FiIe:e:wp7\3100\3104a.pge Page 8 GeoSoils, Inc. 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 contractors 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 techniàian withdraw and notify his/her supervisor. The contractors representative will eventually be contacted in an effort to effect a solution. All backfill not tested due to safety concerns or other reasons could be subject to reprocessing and/or removal. If GSI personnel become aware of anyone working beneath an unsafe trench wall or vertical excavation, we have a legal obligation to put the contractor and owner/developer on notice to immediately correct the situation. If corrective steps are not taken, GSI then has an obligation to notify CAL-OSHA and/or the proper authorities. Mr. David Thompson Appendix FBe:e:wp7\3100\3104a.pge Page 9 GeoSoils, Inc. RECEIVED NOV - 1 ZUlu ENGINEERING DEPARTMENT