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Home My WebLink AboutCUP 01-22; AVIARA COMMUNITY PARK; GEOTECHNICAL INVESTIGATION; 2001-10-12I I I I I I I I I I I I I I I I I I I GEOTECHNICAL INVESTIGATION A VIARA COMMUNITY PARK CARLSBAD, CALIFORNIA TABLE OF CONTENTS 1.0 IN"1RODUCTION .......................................................... 1 2.0 SCOPE OF SERVICES ..................................................... 1 3.0 SITE DESCRIPTION ....................................................... 2 4.0 PROPOSED DEVELOP~NT ............................................... 3 5.0 GEOLOGY AND SUBSURFACE CONDffiONS ................................ 3 5.1 Santiago Formation ................................................... 4 5.2 Alluvium ........................................................... 4 5.3 Colluvium .......................................................... 4 5.4 Structure ........................................................... 5 5 .5 Groundwater ........................................................ 5 6.0 GEOLOGIC HAZARDS AND SEIS:MICITY .................................... 6 6.1 Seismicity .......................................................... 6 6.2 Ground Rupture ..................................................... 7 6.3 Liquefaction and Dynamic Settlement .................................... 7 6.4 Landslides and Lateral Spreads .......................................... 7 6.5 Tsunamis, Seiches, Earthquake Induced Flooding ........................... 8 7.0 CONCLUSIONS ........................................................... 8 8.0 RECOM11ENDATIONS ................................................... 10 8.1 Plan Review ....................................................... 10 8.2 Grading and Excavation Observation .................................... 10 8.3 Earthwork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 8.3 .1 Site Preparation ............................................. 11 8.3.2 Excavation Characteristics ..................................... 12 8.3.3 Bulking and Shrinking Estimates ................................ 12 8.3.4 Temporary Excavations ....................................... 12 8.3.5 Removals .................................................. 13 8.3.6 Keyways and Benching ....................................... 14 8.3.7 Subsurface Drainage Systems .................................. 14 8.3.8 Expansive Soil .............................................. 15 8.3 .9 Cut/Fill Transitions .......................................... 15 8.3.10 Structural Fill Materials ...................................... 16 8.3.11 Fill Compaction ............................................ 17 8.4 Slope Stability ...................................................... 17 8.5 Slope Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 -----------Geotechnics Incorporated ----------- I I I I I I I I I I I I I I I I I I I GEOTECHNICAL INVESTIGATION AVIARA COMMUNITY PARK CARLSBAD, CALIFORNIA TABLE OF CONTENTS (continued) 8.6 Preliminary Foundation Recommendations ............................... 19 8.6.1 Settlement Considerations ..................................... 20 8.6.2 Lateral Loads ............................................... 20 8.6.3 Site Seismic Parameters ....................................... 21 8.6.4 Slope Setback ............................................... 21 8. 7 On-Grade Slabs ..................................................... 21 8. 7 .1 Moisture Protection for Interior Slabs ............................ 21 8.7.2 Exterior Slabs ............................................... 22 8.8 Earth Retaining Structures ............................................ 22 8.9 Pipelines .......................................................... 23 8.9.1 Thrust Blocks ............................................... 23 8.9.2 Modulus of Soil Reaction ...................................... 23 8.9.3 Pipe Bedding ................................................ 24 8.10 Pavements ........................................................ 24 8.11 Reactive Soils ..................................................... 25 9.0 LIMITATIONS OF JNVESTIGATION ........................................ 25 ILLUSTRATIONS Site Location Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 1 Fault Location Map ...................................................... Figure 2 Subdrain Detail ......................................................... Figure 3 Slope Drain Detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 4 Transition Details ........................................................ Figure 5 Wall Drain Detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Figure 6 Geotechnical Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Plate 1 APPENDICES REFERENCES ...................................................... Appendix A FIELD EXPLORATION ............................................... Appendix B LABORATORY TESTING ............................................. Appendix C SLOPE STABILITY ANALYSIS ........................................ Appendix D -----------Geotechnics Incorporated ------------ I I I I I I I I I I I I I I I I I I I P&D CONSULT ANTS OCTOBER 12, 2001 PROJECT NO. 0669-001-00 DOCUMENT NO. 1-0805 PAGE! GEOTECHNICAL INVESTIGATION A VIARA COl\.lMUNITY PARK CARLSBAD, CALIFORNIA 1.0 INTRODUCTION This report presents the results of our geotechnical investigation of the community park planned for Aviara in the City of Carlsbad's Zone 19. The purpose of the investigation was to provide preliminary geotechnical recommendations for the proposed earthwork construction of the site. This report presents the results of our subsurface exploration, laboratory testing, engineering analysis, conclusions regarding the feasibility of the proposed improvements, and recommendations regarding the geotechnical aspects of the project. 2.0 SCOPE OF SERVICES This geotechnical investigation was conducted in accordance with the authorization of Mr. Steve Kettler. The scope of services provided during this investigation was consistent with that outlined in our Proposal No. 0-312, and our Changer Order Request dated September 5, 2001. In order to evaluate potential geotechnical impacts to the proposed development, and to provide geotecb,nical recommendations, the following services were performed. • • • Review of pertinent geologic and topographic maps, available literature related to the general geologic and seismic conditions in the area, and evaluation of stereoscopic aerial photographs. The pertinent references are listed in Appendix A. Mobilization for subsurface exploration . Subsurface exploration consisting of drilling seven bucket-auger borings to augment the four borings previously drilled for Aviara Land Associates (Geotechnics Incorporated, 1997). The borings were 30-inches in diameter and drilled to depths up to 100 feet. Samples were collected at selected depths in selected borings. Each boring was logged and then backfilled. The approximate locations of the borings are shown on the Geotechnical Map, Plate 1. The boring logs are presented in Appendix B. -------------Geotechnics Incorporated ------------- P&D CONSULTANTS OCTOBER 12, 2001 PROJECT NO. 0669-001-00 DOCUMENT NO. 1-0805 PAGE2 • Laboratory analysis of selected samples retrieved from the excavations. The analysis consisted of unit weight and moisture content, maximum density/optimum moisture content, sieve analysis, Atterberg limits, direct and residual shear strength, expansion index, R-value, pH, resistivity, and soluble sulfate content testing. The test results are presented in Appendix C. • Evaluation of the site's seismicity and potential geologic hazards. • Engineering analyses including evaluation of slope stability (Appendix D), bearing capacity and frictional resistance, lateral earth pressures, preliminary pavement sections, bulking/shrinkage estimates, and the corrosiveness of the soil. • Preparation of this report presenting the results of the subsurface exploration and laboratory testing, conclusions regarding the suitability of the site for its proposed improvements, and geotechnical recommendations regarding earthwork construction and retaining wall design. Preliminary recommendations for foundation design and slab design are also provided. 3.0 SITE DESCRIPTION The proposed park site is situated along the north perimeter of the A viara development, at the northern terminus of Ambrosia Road as shown on the Site Location Map, Figure 1. The site encompasses approximately 25 acres of land that is situated on the northern edge of an irregularly- shaped mesa that overlooks the Palomar Airport industrial center. The site is bound by Poinsettia Lane and Ambrosia Lane on the south, residential developments on the southeast and east, an industrial park on the northeast, and relatively undisturbed native habitat on the northwest and west. The site includes relatively level land within the mesa top area, and rugged slopes and a canyon drainage to the north. Portions of the existing slopes along the northern portion of the site include steep scarps at inclinations steeper than ¾: 1 (horizontal:vertical). Existing elevations at the site range from approximately 326 feet above mean sea level (MSL) in mesa area, to 208 feet MSL ·n one of the canyon bottoms at the--northern end of the site. Much of the mesa area has been cultivated to grow flowers. The existing improvements include unpaved roads and a buried irrigation system for the flower growing operation; a 30-foot wide CarlsbadMunicipal WaterDistrict(CMWD)easementwithan 18-inchdiametersteel waterpipeline and 12-inch diameter water pipeline along the southern portion of the site; and a 15-foot wide -------------Geotechnics Incorporated ------------- P&D CONSULT ANTS OCTOBER 12, 2001 PROJECT NO. 0669-001-00 DOCUMENT NO. 1-0805 PAGE3 CMWD easement containing a 12-inch diameter steel water line along the eastern side of the site. The slope areas include native and non-native vegetation. 4.0 PROPOSED DEVELOPMENT Based on the Preferred Master Plan prepared by P&D Consultants, Inc. (2001), the site will be used as a community park for the residents of Carlsbad. The park will include soccer fields, a softball diamond, a basketball court, a community building, group picnic areas, a restroom, a maintenance facility, and parking areas. The community building is anticipated to be one-and two-stories high while the other buildings are anticipated to be one story. Typical slab-on-grade floors with conventional foundations are anticipated. Public access to the park site will be primarily from Ambrosia Lane. The maintenance facility will be accessed from Poinsettia Lane. The proposed improvements will entail grading of the site to generate level pads for the buildings and level playing fields. The grading will result in fill being constructed above the existing natural slopes along the northern site boundary, a fill slope ascending from the eastern site boundary, and a cut slope along the western site boundary. The existing graded slopes along Poinsettia Lane and Ambrosia Lane will remain nearly unchanged, as will much of the existing graded slope between the site and the residential development to the southeast. The proposed fill slopes will be up to 70 feet high and the proposed cut slopes will be up to 20 feet high. The resulting fill-over-natural slopes will be up to roughly 120 feet high. 5.0 GEOLOGY AND SUBSURFACE CONDITIONS The project is located within the Peninsular Ranges Geomorphic Province of California. This province, which stretches from the Los Angeles basin to the tip of Baja California, is characterized as a series of northwest trending mountain ranges separated by subparallel fault zones, and a coastal plain of subdued landforms. The mountain ranges are underlain primarily by Mesozoic metamorphic rocks that were intruded by plutonic rocks of the southern California batholith, while the coastal plain is underlain by subsequently deposited marine and nonmarine sedimentary formations. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSUL TANfS OCTOBER 12. 2001 PROJECT NO. 0669-001-00 DOCUMENfNO. 1-0805 PAGE4 The subject site is located within the coastal plain portion of the Peninsular Ranges Geomorphic Province. Specifically, the site is underlain by an Eocene-age sedimentary formation known as the Santiago Formation, with overlying surficial deposits of colluvium and alluvium. The lateral extent of the geologic units is shown on the Geotechnical Map, Plate 1. Generalized descriptions, from oldest to youngest, are as follows. 5.1 Santiago Formation The Santiago Formation underlies the entire site at depth. As observed in the borings, the Santiago Formation consists primarily of massive silty sandstone ·with relatively thin interbeds of fat claystone. The sandstone is yellow to olive bro\'\n in color, fine to medium grained, and moderately cemented with few strongly cemented layers that are likely localized concretions. The claystone is olive brown in color, exhibits medium to high plasticity, and is moderately indurated. Fossil bi-valves and other shell fragments were observed in discrete beds. A seam of clay was also encountered in two of the borings (B-10 and B-11 ). The clay seam is soft, 1/a-to ¼-inch thick, and apparently continuous in the central portion of the site at an elevation of approximately 213 feet MSL. 5.2 Alluvium In general, alluvial soils infill the lower elevations of the canyon bottom located at the northern end of the site. The alluvium consists generally of brown silty sand that is loose. As observed in the boring B-2, the thickness of alluvium is up to roughly 15 feet. Thicker accumulations may exist. 5.3 Colluvium Colluvium mantles much of the slopes and, in general, covers the mesa top. These materials consist of brown, silty to clayey, loose sand and firm, sandy lean clay. These materials are generally less than 4 feet thick as observed in the borings. Much of the colluvium over the mesa top has been tilled as part of the flower growing operation. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULTANTS OCTOBER 12. 2001 5.4 Structure PROJECT NO. 0669-001-00 DOCUMENTNO. 1-0805 PAGES The sandstone portion of the Santiago Formation, as observed in the borings, is generally massive with few zones of cross-bedding. The claystone interbeds are generally flat-lying although some inclination is observed near slope faces. The inclined or dipping beds may be associated with downslope creep of the slopes' outer portions. Faulting was encountered in borings B-1 and B-6. In B-1, the apparent fault was observed approximately 6 feet beneath the surface. This feature was oriented northeast/southwest (N35°E) and dipped to the northwest approximately 66° from horizontal. In boring B-6, a relatively thick fault gouge zone was encountered between elevations of approximately 229 and 239 feet MSL. The top of the gouge was oriented Nl5°E and dipped to the northwest at approximately 58° from horizontal. The bottom of the gouge was oriented N22°E and also dipped to the northwest at approximately 59° from horizontal. The fault gouge included shear surfaces of soft clay. The sandstone above the fault included randomly oriented :fractures that were near vertical in orientation. Evidence of the faults offsetting the overlying surficial deposits was not found. 5.5 Groundwater Groundwater was encountered in several of the borings that were located along the edge of the mesa. In general, groundwater seepage was encountered at elevations between 183 and 240 feet MSL in confined zones with greater permeability. There did not appear to be a consistent groundwater table. Based on the proposed grading, significant groundwater is not anticipated to be encountered. However, excavations at lower elevations will likely encounter some seepage. Subsurface water conditions may fluctuate during periods of significant rainfall or due to changes in on-site, nearby irrigation, or broken pipes. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSUL TA,'ITS OCTOBER 12, 2001 6.0 GEOLOGIC HAZARDS AND SEIS:MICITY PROJECT NO. 0669-001-00 DOCUMENT NO. 1-0805 PAGE6 The subject site is not located within an area previously known for significant geologic hazards including active faulting, lique:fiable soils, or collapsible soils. Several northeast-southwest trending faults were encountered in the eastern part of the site during the subsurface exploration. However, evidence of active faulting as defined by offset Holocene-age deposits, was not found. The existence of the faults increases the potential for slope instabilities, but do not represent zones of potential surface rupture. Potential geologic hazards at the site are as follows: 6.1 Seismicity Seismic hazards at the site are anticipated to be caused primarily by ground shaking during seismic events on adjacent active faults. Figure 2, the Fault Location Map, shows the general location of the site in relation to active and potentially active faults in southern California and northern Baja California. The nearest known active fault is the Rose Canyon fault zone, located approximately 5½ miles (9 kilometers) southwest of the site. The Rose Canyon fault zone is a Type B fault (California Department of Conservation, 1998). The nearest known Type A fault is the Elsinore fault zone located approximately 23 miles northeast of the subject site. Site coordinates of latitude 33.1144° north and longitude 117.2817° west were estimated using the computer program 3-D TopoQuads. The site coordinates were used in the computer program EQF AULT (Blake, 1998) to estimate peak horizontal accelerations from regional faults. The deterministic values of peak ground acceleration for known active faults within 100 kilometers of the site are presented in Table 1 for comparison with the probabilistic values presented below. The computer program FRISKSP was used to perform a probabilistic analysis of seismicity at the site based on the characteristic earthquake distribution of Youngs and Coopersmith (1985). Based on the results of the probabilistic analysis, the ground acceleration for the site from the Upper Bound Earthquake, defined as the motion having a 10% probability of being exceeded in 100 year~ is 0.36g. The ground acceleration for the site from the Design Basis Earthquake is 0.30g (10% probability of being exceeded in 50 years). -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I P&D CONSULTANTS OCTOBER 12, 2001 6.2 Ground Rupture PROJECT NO. 0669-001-00 DOCUMENTNO. 1-0805 PAGE7 Surface rupture is the result of movement along an active fault reaching the surface. The Fault Location Map, Figure 2, shows the relationship between known active faults in the region and the site. There are no known active faults underlying the site or projecting toward the site. Evidence of active faulting was not found at the site. The site is not located in an Alquist-Priolo Earthquake Fault Zone. In our opinion., there is little probability of surface rupture due to faulting beneath the site; however, lurching and ground cracking are a possibility as a result of a significant seismic event on a regional active fault. 6.3 Liquefaction and Dynamic Settlement Liquefaction is a process in which soil grains in a saturated deposit lose contact due to earthquakes or other sources of ground shaking. The soil deposit temporarily behaves as a viscous fluid; pore pressures rise, and the strength of the deposit is greatly diminished. Liquefaction is often accompanied by sand boils, lateral spread, and post-liquefaction settlement as the pore pressures dissipate. Liquefiable soils typically consist of cohesionless sands and silts that are loose to medium dense, and saturated. Clayey soil deposits do not liquefy because the soil skeleton is not supported by grain to grain contact, and is therefore not subject to densification by shaking. To liquefy, soils must be subjected to a ground shaking of sufficient magnitude and duration. The portion of the site where improvements are planned is underlain primarily by very dense formational materials ,vith a relatively minor amount of surficial soil. The surficial soil ·will be removed and replaced as compacted fill as part of the site's development. Also, there does not appear to be a shallow water table beneath the site. Follmving development of the site, the potential for liquefaction and associated dynamic settlement to occur at the site is remote in our opinion. 6.4 Landslides and Lateral Spreads Evidence of existing landslides at the site was not found. However, some of the existing bluffs and slopes along the northern site boundary and within the canyon area do not meet the industry standard minimum factor-of-safety of 1.5 regarding deep-seated slope stability. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULTA.i-....'TS OCTOBER 12, 2001 PROJECTNO. 0669-001-00 DOCUMENTNO. 1-0805 PAGES Some of the planned fills impose additional loads to the existing natural slopes which are in part underlain by a soft clay seam or shear surfaces associated with the existing faults. The stability of the on-site slopes should be enhanced by remedial grading as recommended in later sections of this report. The stability of the off-site slopes is not, in our opinion, significantly affected by the proposed development. 6.5 Tsunamis, Seiches, Earthquake Induced Flooding The project site is located at elevations above 100 feet above mean sea level. Documented accounts, or predicted run-up heights for coastal Southern California using 100-year and 500- year events, do not exceed 15 feet above mean sea level. Accordingly, the potential for flooding at the site due to tsunami is remote. Open bodies of water were not found near the site. Accordingly, the potential from flooding at the site caused by a seiche appears remote. 7.0 CONCLUSIONS Based on the results of this investigation, it is our opinion that the proposed development is feasible from a geotechnical standpoint provided the following recommendations and appropriate construction practices are followed. No geotechnical conditions were encountered that would preclude the proposed construction. The existence of a soft clay seam at approximate elevation 213 feet MSL, and the existence of fault gouge, "\\ill impact the stability of the existing slopes in the northern part of the site. Geotechnical design and construction considerations include the follmving: • There are no kno-wn active faults underlying the project site. Potential seismic hazards at the site are associated with ground shaking from an event along nearby active faults, such as the Rose Canyon fault zone located approximately 5½ miles southwest of the site. This hazard is typically mitigated through design in accordance with the California Building Code. • Evidence of existing slope failures was not found; however, the factors-of-safety regarding the stability of some of the existing slopes adjacent to the project boundaries and ,vi thin the canyon area do not meet the industry standard minimum factor-of-safety of 1.5 for gross stability. The addition of the proposed fill slopes will not significantly reduce the stability -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULTA¾"TS OCTOBER 12. 2001 PROJECT NO. 0669-001-00 DOClTh1E1\1T NO. 1-0805 PAGE9 • • • • • • of these existing slopes, and, in some cases, improves their stability provided the recommendations presented in Section 8.4 of this report. Excavations at the site should generally be achievable using standard excavation equipment in good-working order with eA'}Jerienced operators. Zones of strongly cemented material may be encountered that will require e::\.'tra ripping effort to dislodge. The site is mantled with compressible colluvium that is considered unsuitable for the direct support of settlement sensitive improvements or fills. Recommendations for removing and replacing the compressible materials are presented in the following sections. Some portions of the on-site materials may include highly expansive soil. Highly expansive soil may cause heave-related distress to foundations. slabs, retaining walls, and other improvements if placed near finish grades. Recommendations to reduce the effects of soil heave are provided later in this report. Portions of the proposed building pads may be partially underlain by formational materials and partially by fill once grading is completed. The fill and formational materials will provide different bearing capacities and settlement potentials. Once the conditions beneath each building footprint are known, further excavation in the cut portions of the pad may be recommended to provide uniform bearing conditions and to reduce the effects of differential settlement. Significant groundwater is not anticipated to be encountered in the proposed excavations . However, some groundwater seepage is anticipated in e.'.:cavations at lower elevations. General recommendations for mitigating groundwater are presented in the following sections. The existing water main pipelines and irrigation system will be removed from ,vithin the site as part of the development of the site. The ex1Josed ends out side of the site \\ill act as conduits for soil migration, resulting in surface settlement or sinkholes, if not properly plugged. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULTANTS OCTOBER 12. 2001 8.0 RECOMMENDATIONS PROJECT NO. 0669-001-00 DOCUMENT NO. 1-0805 PAGE IO As indicated in the conclusions section of this report, the fault gouge and clay seam encountered during the subsurface exploration affect the stability of some of the existing slopes. The proposed fill slopes over the existing natural slopes does not impact the stability of the existing slopes in some locations, but in other locations, buttressing of the natural slope is recommended. These recommendations are provided in Section 8.4. The remainder of this report presents recommendations for earthwork and construction of the proposed improvements, as well as preliminary geotechnical recommendations for the design of foundations for structures up to two stories tall. These recommendations are based on empirical and analytical methods typical of the standard-of-practice in southern California. If these recommendations appear not to address a specific feature of the project, please contact our office for additions or revisions to the recommendations. 8.1 Plan Review It is recommended that foundation and grading plans be reviewed by Geotechnics Incorporated prior to plan finalization. Significant changes in the development from the preliminary plans used for this investigation may require additional geotechnical evaluation. 8.2 Grading and Excavation Observation Foundation excavations and site grading should be observed by Geotechnics Incorporated. During grading, Geotechnics Incorporated should provide observation and testing services continuously. Such observations are considered essential to identify field conditions that differ from those anticipated by the preliminary investigation, to adjust designs to actual field conditions, and to determine that the grading is accomplished in general accordance with the recommendations of this report. Recommendations presented in this report are contingent upon Geotechnics Incorporated performing such services. Our personnel should perform sufficient testing of fill during grading to support our professional opinion as to the compliance of the earthwork with the compaction recommendations. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULT ANTS OCTOBER 12. 2001 8.3 Earthwork PROJECT NO. 0669-001-00 DOCUMENT NO. 1-0805 PAGE 11 Earthwork for the proposed development is anticipated to include remedial grading for the buttress and fault gouge removal, the removal of existing compressible, expansive, or otherwise unsuitable soils; and excavation and filling of the pads, slopes, utilities, and street subgrade. Grading and earthwork should be conducted in accordance with the Grading Ordinance of the City of Carlsbad, the California Building Code (CBC), and the recommendations of this report. The following recommendations are provided regarding specific aspects of the proposed earthwork construction. 8.3.1 Site Preparation General site preparation should include the removal of unsuitable and deleterious materials, existing structures, or other improvements from areas that will be subjected to structural or fill loads. Clearing and grubbing should consist of the removal of vegetation including brush, grass, weeds, woods, stumps, trees, tree roots, and otherwise deleterious materials from areas to be graded. Clearing and grubbing should extend to the grading limits. The debris generated by the clearing and grubbing should be legally disposed off-site. All existing buildings, structures, foundations, utilities ( above and below ground), cisterns, wells, tunnels, and any other man-made improvements within the grading limits, that are not to be saved for future use, should be demolished and hauled off- site. Subsurface improvements or obstructions that extend below grade should be excavated and hauled off site. Demolition of pipelines may consist of capping or rerouting at the project perimeter, and removal within the project perimeter. If appropriate, abandoned pipelines may be filled with grout or slurry cement as recommended by, and under the observation of, the geotechnical consultant. Wells, cisterns, seepage pits and shafts should be filled and capped in accordance with the governing authorities. Trees or man-made improvements to be saved should be protected from damage by the contractor. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULT ANTS OCTOBER 12. 2001 8.3.2 Excavation Characteristics PROJECT NO. 0669-001-00 DOCUME1'.1TNO. 1-0805 PAGE 12 In general, excavations should be achievable using standard heavy earthmoving equipment in good working order and operated by e:x.'J)erienced personnel. Some e:\.'ira ripping effort may be desired where strongly cemented concretions within the sandstone are encountered. Excavations in the formational materials may generate oversized materials that will require special handling for reuse in structural fills. Significant quantities of this material, resulting in the construction of --rock fills'', is not anticipated. Special handling may include placing clasts up to 4 feet in dimension in \\-indrows and bucying these material \\1th granular soils and liberal amounts of water to fill any voids. Larger clasts in individual pits and then burying with granular soils and liberal amounts of water to fill any voids. Care should be taken to ensure that clasts are separated adequately to facilitate infilling between the clasts with compacted material. 8.3.3 Bulking and Shrinking Estimates Excavation of the on site materials for re-use in compacted fills will result in some bulking of the formational materials, and shrinking of the loose sur:ficial soils. The formational materials include the Santiago Formation. The sur:ficial soils include the alluvium and colluvium. Based on our experience ,vith projects in nearby locations, and limited laboratory testing of the on-site materials, the formational materials at the site may bulk bet\veen 5 and 15 percent, and the surficial soils may shrink between 5 and IO percent. 8.3.4 Temporary Excavations Temporary excavations. such as for the removal of the fault gouge, unsuitable soils, and for utility trenches, are anticipated to be up to approximately 50 feet in depth. All excavations should be laid back or shored and should conform with Cal-OSHA guidelines. Workmen should be protected from falling rocks in accordance with Cal- OSHA requirements. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULTAi'-l'TS OCTOBER 12. 2001 PROJECT NO. 0669-001-00 DOCUMENT NO. 1-0805 PAGE 13 Temporary slopes excavated within existing colluvium or alluvium should be laid back no steeper than 1: 1 (horizontal to vertical) for excavations no more than 20 feet deep. Should deeper temporary excavations in loose surficial deposits be required, Geotechnics Incorporated should be notified so that additional recommendations may be provided. Temporary excavations up to 50 feet deep in formational materials should generally be laid back no steeper than¾: I. However, an exception to this is the proposed removal of the fault gouge in the northeastern part of the site (see Section 8.4, Slope Stability). The backcut for this excavation may be inclined as steep as ½:I based on our stability analysis. Temporary excavations that encounter seepage or other potentially adverse conditions should be evaluated by the geotecbnical consultant on a case-by-case basis during grading. Remedial measures may include shoring, or reducing the inclination of the temporary slope. For temporary excavations that v.ill be shored, but not braced with tie-backs or struts, we recommend using a triangular pressure distribution for calculating earth pressures, based on the soil conditions. In general, an equivalent fluid pressure of 3 5 lbs/ff may be used for sandy soil, or 55 lbs/ff for clay soil based on level retained ground, plus any groundwater pressures encountered in the excavation, and any surcharge loads resulting from loads placed above the excavation and within a I: 1 plane e}.,1:ending upward from the base of the excavation. Should surcharge loads be anticipated, or braced shoring be used, Geotechnics Incorporated should be contacted for additional design parameters. 8.3.5 Removals Unsuitable materials typically include topsoil, landslide debris, colluvium, alluvium, undocumented or uncompacted fill soils, weathered formational materials, or other soil subject to settlement under increased loads, wetting, or bio-degradation. The removal of unsuitable materials should be conducted under the observation of the geotechnical consultant to evaluate the competency of the exposed materials for support of structural loads. The excavation of unsuitable materials should be conducted in a way that minimizes the disturbance of competent materials. Excavated material that is free of deleterious or oversize materials may be re-used in compacted fills upon evaluation by the geotechnical consultant. Areas where -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULT At"'\1TS OCTOBER 12. 2001 PROJECT NO. 0669-001-00 DOCUME1'.1T NO. 1-0805 PAGEl4 removals are completed should be scarified approximately 8 inches deep, brought to slightly above optimum moisture content, and compacted in accordance with the recommendations contained herein. 8.3.6 Keyways and Benching Keyways should be excavated at the base of :fill slopes under the observation of the geotechnical consultant. The ,vidth and bottom elevation of each keyway should be provided by the geotecbnical consultant based on an evaluation of the site conditions. The minimum key width is 15 feet. The entire key should be excavated into competent formational material or rock and tilted towards the heal of the slope at an inclination of 2 percent or more. The exposed keyway should be scarified to a depth of approximately 8 inches, brought to slightly above optimum moisture content, and compacted prior to placing fill. Where fill is to be placed on surfaces inclined steeper than 5: 1 (horizontal to vertical), benches should be excavated to provide a relatively level surface for fill placement. The benches should e:\.'tend through any loose, unsuitable materials to expose competent material as evaluated by the geotechnical consultant. The bench width should generally be adequate to e:,q,ose 3 to 5 feet of competent material in the vertical wall of the bench. The exposed bench bottoms should be scarified to a depth of approximately 8 inches, brought to slightly above optimum moisture content, and compacted prior to placing fill. Excavated material that is free of deleterious or oversize materials may be re-used in compacted :fills upon evaluation by the geotechnical consultant. 8.3. 7 Subsurface Drainage Systems We recommend that subdrains be installed in the invert of natural drainage channels, and wherever seepage is encountered. Although the installation of canyon subdrains does not appear likely based on the configuration of the site, the location and extent of subdrains should be evaluated during grading by the geotechnical consultant. Subdrains should be constructed as shown in Figure 3. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULT~"ITS OCTOBER 12. 2001 PROJECT NO. 0669-001-00 DOCUMENTNO. 1-0805 PAGE 15 We recommend that composite panel drains be installed where seepage is observed in slopes, including temporary slopes for remedial excavations, and where conditions such as bedding indicate the potential for seepage. In cut slopes, the face of the slope should be over-excavated to result in a temporary slope, no steeper than as evaluated by the geotechnical consultant, and a keyway excavated to a minimum width of 15 feet. The panel drain should be placed so that it covers the areas where seepage is observed or anticipated. Blanket drains or cut-off drains may be needed to control groundwater in pads. The location and extent of the drain should be evaluated by the geotechnical consultant during grading. Figure 4 presents typical details for slope drain construction. 8.3.8 Expansive Soil To reduce the potential for heave of finish grade, we recommend that soil exhibiting an Expansion Index greater than 50, based on UBC Test Method 18-2 or ASTM D4829, be removed from the upper 5 feet of finish grade in pad areas, and the upper 2 feet below exterior flatwork. Testing of the subgrade soils should be conducted during grading to evaluate the expansive nature of the subgrade soils. 8.3.9 Cut/Fill Transitions Depending on the location of the proposed buildings, and the extent of remedial grading, the proposed structures may straddle materials with varying settlement potentials. These conditions generally occur along or near transitions from fill to formational materials. In order to reduce the potential for adverse settlement, we recommend that the cut or formational portion of the pad be over-excavated and replaced with compacted fill. The depth of the over-excavation should be 3 feet below foundation-bottom grade, or to a depth of H/2 where H is the greatest depth of fill beneath the structure, whichever is greater (Figure 5). Pad grade should be re- established with fill compacted as recommended in this report. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULTM1TS OCTOBER 12, 2001 8.3.10 Structural Fill Materials PROJECT NO. 0669-001-00 DOCUMENT NO. 1-0805 PAGE16 Materials being considered for use in compacted fill should be evaluated by the geotechnical consultant prior to placement, but may include materials excavated from cuts, materials excavated during remedial grading (removals), or imported materials. In general, fill soils should be free of deleterious or "oversized" material as defined herein. Fill materials are categorized as "soil" fills, and "soil-rock" fills. "Soil" fills are defined as fills containing no rocks or hard lumps greater than 12 inches in maximum dimension, and containing at least 60 percent by weight material passing a 3/4-inch standard sieve. "Soil-rock" fills are defined as soil fills in which oversize material is disposed of in windrows within the soil fill. The over-size material is limited to 4 feet in maximum dimension. Wmdrows are spaced laterally at least 15 feet, and vertically at least 5 feet. Placement of windrows is staggered to that windrows do not overly each other. Windrows are held back at least 15 feet from the face of slopes and at least 10 feet from finish grades. To facilitate the excavation of footings and utility trenches, it is generally recommended that material greater than 6 inches in dimension not be placed within 3 feet of finish pad grade or street subgrade, or within 2 feet of the deepest utility, whichever is deepest. Rocks or hard clumps greater than 6 inches in dimension should not be used in trench backfill, backfill for reinforced earth walls, or retaining wall backfill. Accordingly, materials generated from excavations in fills including larger material will require screening prior to use as backfill. Imported fill sources, if needed, should be observed prior to hauling onto the site to determine the suitability for use. Representative samples of imported materials and on site soils should be tested by the geotechnical consultant in order to evaluate their appropriate engineering properties for the planned use. During grading operations, soil types other than those analyzed in the geotechnical reports may be encountered by the contractor. The geotechnical consultant should -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULTA.t'l'TS OCTOBER 12. 2001 PROJECT NO. 0669-001-00 DOCUMENTNO. 1-0805 PAGE17 be notified to evaluate the suitability of these soils for use as fill and as finish grade soils. 8.3.11 Fill Compaction All soil fill or soil-rock fill, and backfill, to be placed in association with site development should be accomplished at slightly over optimum moisture conditions and using equipment that is capable of producing a uniformly compacted product. Fill materials at less than optimum moisture content should have ,vater added and the fill mixed to result in material that is uniformly slightly above optimum moisture content. Fill materials that are too wet should be aerated or mixed ""ith drier material to achieve uniformly moisture-conditioned soil. The fill and backfill should be placed in horizontal lifts at a thickness appropriate for the equipment spreading, mixing, and compacting the material, but generally should not exceed 8 inches in loose thickness. The minimum recommended relative compaction for fill and backfill is 90 percent of mawnum density using ASTM D1557 as a guideline. The slope faces should be compacted to the recommended 90 percent relative compaction, either by rolling with a sheepsfoot roller or with other suitable heavy equipment, or by overfilling the slope and cutting back to design grade. Sufficient observation and testing should be performed by the geotechnical consultant so that an opinion can be rendered as to the compaction achieved. 8.4 Slope Stability The gross stability of the existing natural slopes and the proposed fill slopes was evaluated using the computer program PCST ABL5. The sections evaluated are shown with the results of our analysis in Appendix D. Based on our analysis, the northeastern side of the site is subject to slope instabilities due to the existence of faulting. The stability of the existing slopes in the north-central portion of site around the canyon are affected by a clay seam encountered at an elevation of approximately 213 feet MSL. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULTANTS OCTOBER 12. 2001 PROJECT NO. 0669-001-00 DOCUMENT NO. 1-0805 PAGE 18 The faults are not considered active, but do include continuous shear zones of weak strength. Removing portions of the shear zones improves the stability of the existing, and proposed, slopes. We recommend that the fault gouge be removed from elevations above 220 feetMSL in the northeastern part of the site as shown on the attached Geotechnical Map, Plate 1. The excavation should result in a slot approximately 10 feet wide from approximately elevation 220 feet MSL to 228 feet MSL, as approximately shown on Platel, to allow compaction equipment some space for maneuvering. Panel drains should be installed along the bottom of the excavation's backcut, and along any areas of seepage exposed in the backcut, as described in Section 8.3.7. The excavation should be backfilled with compacted fill as recommended herein. To improve slope stability affected by the clay seam, we recommend that the slope be buttressed approximately where shown on the Geotechnical Map, Plate 1. The keyway for the buttress should be approximately 30 feet wide as shown on the Geotechnical Map, and at an elevation that eliminates the clay seam (approximately 213 feet MSL). Panels drains should be installed along the backcut of the excavation to intercept any groundwater seepage encountered. At a minimum, the panel drain should cover the bottom 5 feet of the temporary slope at the backcut. The removal of the fault gouge and clay seam, and the construction of the slopes, should be observed by Geotechnics Incorporated continuously to evaluate the exposed conditions for conformance with anticipated conditions. Should unanticipated planes or zones of weakness exist, additional recommendations will be provided. All slopes are subject to some creep, whether the slopes are natural or man-made. Slope creep is the vezy slow, down-slope movement of the near surface soil along the slope face. The degree and depth of the movement is influenced by soil type and the moisture conditions. This movement is typical in slopes and is not considered a hazard. However, it may affect structures built on or near the slope face. We recommend that structures not be located within 10 feet of the top of the slopes, unless specific evaluation of the structure's foundation is conducted by the geotechnical consultant. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULTA"\ITS OCTOBER 12, 2001 8.5 Slope Protection PROJECT NO. 0669-001-00 DOCUMENT NO. 1-0805 PAGEl9 Surficial slope stability may be enhanced by providing good site drainage. The site should be graded so that water from the surrounding areas is not able to flow over the top of the slope. Diversion structures should be provided where necessary. Surface runoff should be confined to gunite-lined swales or other appropriate devices to reduce the potential for erosion. It is generally recommended that slopes be planted with vegetation that will increase their stability. Ice plant is generally not recommended. We recommend that vegetation include woody plants, along with ground cover. All plants should be adapted for growth in semi-arid climates with little or no irrigation. A landscape architect should be consulted in order to develop a specific planting palate suitable for slope stabiliz.ation. Site irrigation should be limited to the minimum necessary to sustain landscaping plants. 8.6 Preliminary Foundation Recommendations Based on the results of this investigation, conventional shallow foundations are considered suitable for support of the proposed buildings located in the pad areas. The following recommendations are based on the conditions encountered during this investigation and are considered preliminary. Design-level recommendations will be provided based on the as- graded conditions at the site. The following preliminary recommendations are generally consistent with methods typically used in southern California Other alternatives may be available. The following foundation recommendations are minimum criteria based on geotechnical concerns. They should not be considered a structural design, nor should they be considered to preclude more restrictive criteria by governing agencies or the structural engineer. The design of the foundation system should be performed by the project structural engineer. The following design parameters assume that the foundations for the proposed buildings in the pad area will consist of shallow continuous or isolated footings bearing either entirely on compacted fill or formational materials, and that the materials will have a low expansion potential (Expansion Index of 50, or less). -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSUL TA,"\,'TS OCTOBER 12. 2001 Allowable Bearing: Minimum Footing Width: Minimum Footing Depth: ~finimum Reinforcement: PROJECT NO. 0669-001-00 DOCUMENTNO. 1-0805 PAGE20 2,000 psf if underlain by fill, 5,000 psf if underlain entirely by formational material (allow a one-third increase for short-term wind or seismic loads). 12 inches for continuous footings, 24 inches for isolated footings. 24 inches below lowest adjacent e~'terior soil grade. Two No. 4 bars at both top and bottom in continuous footings. The bottoms of the foundation excavations should be observed by Geotechnics to evaluate whether the bearing materials are as anticipated. Loose soils at the bottom of foundation excavations should be removed prior to placing steel and concrete. 8.6.1 Settlement Considerations Settlement resulting from foundation loads is not expected to exceed ¾-inch and ½- inch for total and differential settlement, respectively, across the length of the structures provided the remedial grading recommendations presented herein are followed. The differential fill thickness across the structures should be evaluated for settlement concerns upon completion of grading and determination of final building locations. Any warranted changes to design parameters, or recommendations for remedial grading, should be made at that time. 8.6.2 Lateral Loads Lateral loads may be resisted by friction and by the passive resistance of the supporting soils. A coefficient of friction of 0.3 may be used benveen the bottom of footings and the compacted fill or formational material. The passive resistance of those materials may be assumed to be equal to the pressure developed by a fluid ,vi.th a density of 300 pcf. A one-third increase in the passive values may be used for wind or seismic loads. The passive resistance of the materials may be combined with the frictional resistance without reduction in evaluating the total lateral resistance. -------------Geotecbnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULTA,¾'TS OCTOBER 12, 2001 8.6.3 Site Seismic Parameters PROJECT NO. 0669-001-00 DOCU!1,1ENT NO. 1-0805 PAGE21 The following CBC seismic parameters may be used for site: Seismic Zone Factor, Z: Seismic Source Type: Soil Profile Type: Seismic Coefficients, Ca: CV: Near-Source Factors, Na: Nll: 8.6.4 Slope Setback 0.4 B Sc 0.40Na 0.56N11 1.0 1.1 Foundations constructed near the tops of slopes should be deepened as necessary so that the minimum horizontal distance from the outside bottom edge of the footing to the slope face is 8 feet or more. It should be recognized that the outer few feet of all slopes are susceptible to gradual do\\'ll-slope movements due to slope creep. This will affect hardscape such as concrete slabs. We recommend that settlement sensitive hardscape not be constructed within 5 feet of the top of slopes. 8. 7 On-Grade Slabs Interior building slabs should be supported by formational or compacted fill materials with a low expansion potential (E:x.11ansion Index of 50, or less). Building slabs should be designed for the anticipated loading. If an elastic design is used, a modulus of subgrade reaction of 200 pci may be used. Slabs should be at least 5 inches in thickness and be reinforced with at least No. 3 bars spaced 24 inches on center, each way. Actual slab thickness and reinforcement should be designed by the project structural engineer. 8.7.1 Moisture Protection for Interior Slabs Concrete slabs constructed on soil ultimately cause the moisture content to rise in the underlying soil. This results from continued capillary rise and the termination of normal evapotranspiration. Because normal concrete is permeable, the moisture will ------------Geotecbnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULT A.'-1TS OCTOBER 12, 200 I PROJECT NO. 0669-001-00 DOCUMENT NO. 1-0805 PAGE22 eventually penetrate the slab unless some protection is provided. To decrease the likelihood of problems related to damp slabs, suitable moisture protection measures should be used where moisture sensitive floor coverings or other factors warrant. A commonly used moisture protection consists of about 2 inches of clean sand or gravel covered by "IO-mil visqueen" plastic sheeting. In addition, 2 inches of clean sand or gravel are placed over the plastic to decrease concrete curing problems associated ·with placing concrete directly on an impermeable membrane. However, it has been our e:,,,.-perience that such systems ·will transmit from approximately 6 to 12 pounds of moisture per 1,000 square feet per day. This may be excessive for some applications, particularly for wood floors, vinyl tile, or sheet vinyl. The project architect should review the moisture protection requirements of the proposed flooring system and incorporate an appropriate level of moisture protection as part of the floor co,'ering design. If a higher degree of moisture protection is needed, we should be contacted for additional recommendations. 8.7.2 Exterior Slabs fa1..'ierior slabs should be underlain by at least 2 feet of compacted fill or formational materials having an Expansion Index no greater than 50. E:,,,.'ierior slabs should be at least 5 inches thick and should be reinforced ,vi.th at least No. 3 rebar spaced 24 inches on center each way, or with 6-inch x 6-inch, W2.9 x W2.9 welded wire fabric placed at slab mid-height. Crack control joints should be used on all e>..'ierior slabs, with a ma-ximum spacing of 5-foot centers each way for sidewalks and IO-foot centers each way for slabs. Differential movement between sidewalks and curbs may be decreased by dowelling the slab into the curb. 8.8 Earth Retaining Structures For cantilever retaining walls, where the backfill is level or nearly level, an active earth pressure approximated by an equivalent fluid pressure of 35 lbs/ft' may be used. Where the earth slopes upwards at 2:1, an equivalent fluid pressure of 50 lbs/ft' may be used. The active pressure should be used for walls free to yield at the top at least 0.2 percent of the wall height. For walls restrained so that such movement is not permitted, an equivalent fluid pressure of 55 lbs/ft' should be used, based on at-rest soil conditions ,,ith level backfill. In -------------Geotecbnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULT Ai""-'TS OCTOBER 12. 2001 PROJECT NO. 0669-001-00 DOCUMENTNO. 1-0805 PAGE23 addition to the recommended earth pressure, walls adjacent to vehicular traffic should be designed to resist a uniform lateral pressure of 100 lbs/:ft2, acting as a result of an assumed 300 lbs/ft:2 surcharge behind the wall. The above pressures assume no hydrostatic pressures. If these are applicable, they will increase the lateral pressures on the wall and we should be contacted for additional recommendations. \Valls should contain an adequate sub drain to reduce hydrostatic forces. \Vall drain details are given in Figure 6, Wall Drain Details. Backfilling retaining walls with expansive soils can increase lateral pressures well beyond the active or at-rest pressures indicated above. We recommend that retaining walls be backfilled with soil having an Expansion Index of 20 or less. The backfill area should include the zone defined by a 1: 1 sloping plane projected from the base of the wall. Retaining wall backfill should be compacted to at least 90 percent relative compaction, based on ASTM D 1557. Backfill should not be placed until walls have achieved adequate structural strength. Heavy compaction equipment ,vhich could cause distress to walls should not be used. 8.9 Pipelines The improvements will likely include storm drains, sanitary sewer, and water pipelines. Geotechnical aspects of pipeline design include lateral earth pressures for thrust blocks, modulus of soil reaction, and pipe bedding. 8.9.1 Thrust Blocks Lateral resistance for thrust blocks may be determined by a passive pressure value of 300 lbs/:ft2 for every foot of embedment assuming a triangular pressure distribution. This value may be used for thrust blocks embedded in either compacted fill or formational materials. 8.9.2 Modulus of Soil Reaction The modulus of soil reaction (E') is used to characterize the stiffness of soil backfill placed along the sides of buried flexible pipelines. For the purpose of evaluating deflection due to the load associated with trench backfill over the pipe, a value of -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULT ANTS OCTOBER 12, 2001 PROJECT NO. 0669-001-00 DOCUMENT NO. 1-0805 PAGE24 1,500 lbs/in2 is recommended for the general site conditions assuming granular bedding material is placed adjacent to the pipe. 8.9.3 Pipe Bedding Typical pipe bedding as specified in the Standard Specifications for Public Works Construction may be used. As a minimrun, we recommend that pipe be supported on at least 4 inches of granular bedding material such as 3/4-inch rock. Where pipeline or trench excavation inclinations exceed 15 percent, we do not recommend that open graded rock be used for pipe bedding or backfill because of the potential for piping and internal erosion of the overlying backfill. The recommended bedding is a coarse sand having a sand equivalent value greater than 30. Alternatively, a sand-cement slurry can be used for the bedding. The slurry should consist of at least a 2-sack mix having a slump no greater than 5 inches. If the sand-cement slurry is used for the pipe bedding and as backfill to at least 1 foot over the top of the pipe, cut-off walls may not be considered necessary. This recommendation should be further evaluated by the project civil engineer designing the pipe system. 8.10 Pavements For preliminary planning purposes, pavement sections are provided based on a selected soil sample collected during our subsurface explorations. The actual pavement section(s) should be based on R-value test results of samples collected from the finished subgrade. Traffic Indices of 4.5 and 6.0 were assumed. R-V alue laboratory testing performed on a sample of the on-site materials indicate an R-Value of 30. The asphalt concrete pavement sections shown in the table below are based on Caltrans design method {Topic 608.4). Preliminary Pavement Sections Traffic Asphalt Concrete Aggregate Base R-Value Index (inches) (inches) 4.5 30 3 5 6.0 30 3 9 -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I P&D CONSULTANTS OCTOBER 12, 2001 PROJECT NO. 0669-001-00 DOCUMENT NO. 1-0805 PAGE25 Subgrade preparation should be conducted immediately prior to the placement of the pavement section. The upper 12 inches of pavement subgrade should be scarifie~ brought to about optimum moisture content, and compacted to at least 95 percent of the maximum dry density determined in accordance with ASTM D 1557. Aggregate base materials should conform to the specifications for Class 2 aggregate base as defined in Section 26 of the latest edition of the State of California, Department of Transportation, Standard Specifications, or tot eh specifications for Crushed Aggregate Base. Crushed Miscellaneous Base, or Processed Miscellaneous Base as defined in Section 200-2.2 of the latest edition of the Standard Specifications for Public Works Construction, '"Greenbook." Aggregate base should be compacted to at least 95 percent relative compaction. Asphalt concrete should be compacted to at least 95 percent of the Hveem unit weight. 8.11 Reactive Soils Soils that will be in contact with concrete should be evaluated for sulfate content after finish grading has been completed. Based on the sample tested during this investigation, the sulfate exposure of concrete in contact with the on-site soils should be negligible. We recommend that additional testing be conducted on the soil exposed at finish grade upon completion of the proposed earthwork. The type of cement used should be based on the results of sulfate content testing and the design criteria of the 1998 California Building Code. It should be noted that soluble sulfate in the irrigation water supply, and/ or the use of fertilizer may cause the sulfate content in the surficial soils to increase with time. This may result in a higher sulfate exposure than that indicated by the test results reported herein. Studies have shown that the use of improved cements in the concrete, and a low water-cement ratio will improve the resistance of the concrete to sulfate exposure. 9.0 LIMITATIONS OF INVESTIGATION This investigation was performed using the degree of care and skill ordinarily exercise~ under similar circumstances, by reputable geotechnical consultants practicing in this or similar localities. No other warranty, expressed or implie~ is made as to the conclusions and professional opinions included in this report. The samples taken and used for testing and the observations made are believed representative of the project site; however. soil and geologic conditions can vary -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I APPENDIX A REFERENCES Abramson, L. W., et al. (I 996). Slope Stability and Stabilization Methods, John Wiley and Sons. American Society for Testing and Materials, 1992, Annual Book of ASTM Standards, Section 4, Construction, Volume 04.08 Soil and Rock; Dimension Stone; Geosynthetics: ASTM, Philadelphia, PA, 1296 p. Anderson, J. G., Rock-well, T. K., Agnew, D. C., 1989, Past and Possible Future Earthquakes of Significance to the San Diego Region: Earthquake Spectra, Vol. 5, No. 2. pp 299-335. Blake, T .F. ( 1998). EQF AULT, EQRJSK, and FRJSKSP: Computer Programs for the Estimation of Peak Horizontal Acceleration From Southern California Historical Earthquakes. California Department of Conservation Division of Mines and Geology, 1998, Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions ofNevada: International Conference of Building Officials, Sheet 0-36. Geotechnics Incorporated, 2000, Proposal for Geotechnical Investigation, Aviara Community Park, Carlsbad, California, Proposal No. 0-312, Document No. 0-1309, dated December 14. Geotechnics Incorporated, 2001, Request for Additional Budget, Geotechnical Investigation, A viara Community Park, Carlsbad, California: Project No. 0669-001-00, Document No. 1-0997, dated September 5. International Conference ofBuilding Officials, 1997, Uniform Building Code ( with California 1998 Amendments). Jennings, C. W., 1994a, FaultActivityMapofCaliforniaandAdjacentAreas: CaliforniaDivision of Mines and Geology, California, Geologic Data Map Series, Map No. 6. Jennings, C. W., 1994b, Selected Faults in Northern California, Offshore, and Adjacent Southern California Area: California Division of Mines and Geology, Geologic Data Map Series, p 1. P&D Consultants, Inc., 2001, undated, untitled plan showing proposed grades at 1 inch= 40 feet. U. S. Department of Agriculture, 1953, Stereoscopic Aerial Photographs: Flight No. AXN-8M Photos 71 and 72, dated April 11. Youngs, R.R. and Coppersmith, K.J. (1985). Implications of Fault Slip Rates and Earthquake Recurrence Models to Probabilistic Seismic Hazard Estimates, Bulletin of the Seismological Society of America, vol. 75, no. 4, pp. 939-964. ------------Geotechnics Incorporated ------------ I I I I I I I I I I I I I I I I I I I APPENDIXB FIELD EXPLORATION Field exploration consisted of a visual reconnaissance of the site, and the drilling of 11 bucket-auger borings. The borings were drilled with a truck-mounted rig to depths of up to 100 feet. The 30-inch diameter excavations were downhole logged by our geologist. Soil samples were visually classified in the field and retained for laboratory testing. The approximate locations of the borings are shown on the Geotechnical Map, Plate 1. Logs describing the subsurface conditions encountered are presented on the following Figures B-1 through B-26. Relatively undisturbed samples were collected using a modified California sampler (CAL). The CAL sampler is a ring-lined tube with an inside diameter of23/e inches and an outside diameter of 3 inches. Ring samples were sealed in plastic bags, placed in rigid plastic containers, labeled, and returned to the laboratory for testing. The relatively undisturbed CAL samples collected from the bucket-auger borings were driven with a kelly weight with a free fall of 12 inches. The kelly weighed 4,500 pounds at depths between O and 27 feet; 3,700 pounds at depths between 27 and 52 feet; 2,700 pounds at depths between 52 and 77 feet; and 1,000 pounds at depths between 77 and 102 feet. For each sample, we recorded the number of blows needed to drive the sampler 6 and 12 inches. The number of blows needed to drive the total 12 inches is shown on the attached logs under "blows per ft." Bulk samples were also obtained at selected intervals. The borings were located by landmarks shown on the Geotechnical Map. The locations shown should not be considered more accurate than is implied by the method of measurement used and the scale of the map. The lines designating the interface between differing soil materials on the logs may be abrupt or gradational. Further, soil conditions at locations between the excavations may be substantially different from those at the specific locations explored. It should be recognized that the passage of time can result in changes in the soil conditions reported in our logs. -------------Geotechnics Incorporated ------------- LOG OF EXPLORATION BORING NO. 8-1 Logged by: LPS Date: 8/20/97 Method of DrillinQ: 30-inch diameter bucket auger Elevation: 269' MSL I=" ._; w w ii:' ~ u. .J .J w 0:: a. a. 0 e:.. w w w :Ii: ~ 0:: !:!:.. a. c( ~ ::, DESCRIPTION LAB TESTS :i: II) II) II) I-I-3:: w ~ II) II) a. 2: .J z 0 w 0 0:: ::, w :Ii: 0 .J ID 0 ID 0 1 COLLUVIUM: Silty sand (SM), dusky brown, fine grained, dry to moist, loose, few gravel. 2 3 SANTIAGO FORMATION: Silty sandstone, yellow gray, fine to medium grained, moist, weakly cemented, few fractures. 4 5 6 Fault: N35E/66NW Lean claystone, olive gray, low plasticity, moist, moderately indurated, 7 massive. 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 lnterbedded clayey sandstone, dark brown, fine grained, moist to wet, 23 weakly cemented. Lean claystone, olive gray, low plasticity, moist, moderately indurated, 24 massive. 25 26 ----------------------------------------------------------------------------- 27 Silty sandstone, light gray, fine to medium grained, moist, moderately cemented, cross bedded, some randomly oriented fractures. 28 29 30 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-1 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-1 (Continued) Logged by: LPS Date: 8/20/97 Method of Drillin_g: 30-inch diameter bucket auger Elevation: 269' MSL i=' ,-: w w i'.i:" ~ u. ..I ..I w 0:: a. a. 0 w w :1: :1: e:.. !:!::. w 0:: a. ct: ct: ~ :::, DESCRIPTION LAB TESTS :c tn rn Cl) t-t-~ w ~ U) Cl) a. > ..I z 0 w ii: :::, w :1: Q ..I £0 0 £0 Q 31 SANTIAGO FORMATION (continued): Silty sandstone, light gray, fine to medium grained, moist, moderately cemented. 32 33 34 35 Thin laminae of clayey sandstone, olive gray, fine grained. 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 Interbed of claystone, sheared appearance, discontinuous, wet, gypsum crystals, bedding oriented: N55E/6SE. 51 52 53 54 55 lnterbed of claystone, gray, medium plasticity, moist, weakly indurated, 56 oriented: N28E/6SE. 57 58 59 60 PROJECT NO. 0669-001-00GEOTECHNICS INCORPORATED FIGURE: B-2 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-1 {Continued) Logged by: LPS Date: 8/20/97 Method of Drilling: 30-inch diameter bucket auger Elevation: 269' MSL i=-..: w w ii:' ';/!. 11. ...I ...I (.) w 0: a. a. w w :IE :IE e::. ~ w 0: a. ~ ~ ~ ::, DESCRIPTION LAB TESTS :c Cl) Cl) Cl) I-I-§ w ~ en Cl) a. > ...I z 0 w ii: ::, w :IE C ...I ID C IXI C 61 SANTIAGO FORMATION (continued): Silty sandstone, light gray, fine to medium grained, moist, moderately cemented. 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 Groundwater seepage. 86 Lean claystone, dark gray, low plasticity, moist, strongly indurated, some gypsum crystals, slightly undulating. Bedding oriented: N25WflSW 87 Silty sandstone, yellow gray, fine grained, moist to wet, moderately 88 cemented, some mottling. 89 90 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-3 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-1 (Continued) Logged by: LPS Date: 8/20/97 Method of Drilling: 30-inch diameter bucket auger Elevation: 269' MSL i=' i-: w w ii:' ~ LI. ...I ...I w 0:: .D.. .D.. 0 e:. w w w ::!: ::!: ~ !:!::. .D.. <C <C ~ ::, DESCRIPTION LAB TESTS ::c u, u, u, I-I-~ w ~ u, u, .D.. > ...I z 0 w ii: ::, w ::!: C ...I C IXl C IXl 91 SANTIAGO FORMATION (continued): Silty sandstone, light gray, fine grained, moist, moderately cemented. 92 93 94 Grades to yellow orange. 95 96 97 98 99 100 101 Total depth: 100 feet 102 Groundwater seepage at 85 feet No caving 103 Backfilled: 8/20/97 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-4 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-2 Logged by: DR Date: 8/20/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 211' MSL i=' i-= w w u:-.f-LI. ...I ...I 0 w ix: a. a. w w w :!: :!: e::. ix: lb a. <C <C ~ ::, DESCRIPTION LAB TESTS :::c en en en I-I-;: w X: en en a. 2: ...I z 6 w 0 ix: ::, w :!: .a ...I .a c.o .a c.o 1 ALLUVIUM: Silty sand (SM), brown, fine grained, moist, loose, porous. 2 Pale olive brown, moist 3 4 5 6 7 8 9 10 Dark brown, wet, some clay. 11 12 13 Clayey sand (SC), yellow brown, fine grained, wet, loose. 14 15 16 SANTIAGO FORMATION: Clayey sandstone, pale olive gray, fine to medium grained, wet, weakly cemented. 17 18 19 Total depth: 18feet 20 No groundwater seepage No caving 21 Backfilled: 8/20/97 22 23 24 25 26 27 28 29 30 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-5 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-3 Logged by: DR Date: 8/20/01 Method of Drilling: 30-inch diameter bucket auaer Elevation: 279' MSL j::' ..,: w w ii:' .,. LI. ...I ...I w 0:: a. a. 0 w ::!: ::!: e:. w w 0:: !!::. a. < ~ ~ :::, DESCRIPTION LAB TESTS ::c ti) ti) f-I-== w ~ ci.i Cl) a. > ...I z 5 w 0 ii: :::, w a ...I ::!: m C m C 1 COLLUVIUM: Sandy lean clay (CL), dusky brown, medium plasticity, dry to moist, finn. 2 3 4 SANTIAGO FORMATION: Silty sandstone, pale olive gray, fine grained, dry to moist, weakly cemented. 5 6 Total depth: 4 feet 7 No groundwater seepage No caving 8 Backfilled: 8/20/97 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-6 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-4 Logged by: DR Date: 8/20/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 280' MSL i=' ..,: w w ii:' ~ u. ..J ..J 0 0 w a:: a. a. w :e e:. w w :e a:: !6. a. < < ~ :::, DESCRIPTION LAB TESTS ::c Cl) Cl) Cl) I-I-3: w ~ u; Cl) a. > ..J z 0 w 0 ii: :::, w :e C ..J C al C al 1 COLLUVIUM: Sandy lean clay (CL), dusky brown, medium plasticity, dry to moist, firm. 2 3 4 5 6 7 SANTIAGO FORMATION: Silty sandstone, pale olive gray, fine grained, dry to moist, weakly cemented. 8 9 Total depth: 8 feet 10 No groundwater seepage No caving 11 Backfilled: 8/20/97 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-7 LOG OF EXPLORATION BORING NO. B-5 Logged by: JCS Date: 7/25/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 323' MSL i=-.,_; w w u: ~ IL. ..J ..J w 0. (.J 0 w 0:: ::!! 0. e:. w w ~ 0:: it:. 0. <I: ~ ::> DESCRIPTION LAB TESTS :c "' "' 1/) t-t-~ w ~ in fl) 0. > ..I z 0 w 0 ii: ::> w ::!! 0 ..J Ill 0 Ill 0 1 COLLUVIUM: Clayey sand with gravel (SC), reddish brown, fine to medium, moist, few cobbles. 2 SANTIAGO FORMATION: Silty sandstone, orange-brown, fine to medium 3 grained, moist, weakly to moderately cemented, few gravel. 4 Sieve Analysis 5 Atterberg Limits 5/ Sulfate, pH 6 8" 112 11.0 Resistivity R-value 7 Direct Shear 8 9 10 11 12 13 14 15 16 17 18 Light olive green, fine grained, moderately cemented, massive. 19 20 21 22 23 24 25 26 27 28 29 30 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-8 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-5 (Continued) Logged by: JCS Date: 7/25/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 323' MSL i=' i-: w w ii:" ~ LI. ..J ..J w a. a. 0 0 w a: :!!: :!!: !!::. w !:::. w a: a. < < ~ :::, DESCRIPTION LAB TESTS :x: U) U) U) I-I-~ w ~ iii U) a. > ..J z 0 w ii: :::, w :!!: C ..J C m Q m 31 SANTIAGO FORMATION (continued): Silty sandstone, light olive green, fine grained, moist, weakly to moderately 32 cemented. 33 34 35 Moderately to strongly cemented. 36 37 Color change to yellowish gray. 38 39 40 41 42 43 44 45 46 47 48 49 50 51 Gray, fine grained, moderately cemented, massive, occasional zones of iron oxide staining. 52 53 54 55 56 57 58 59 60 PROJECT NO. 066!M>01-00 GEOTECHNICS INCORPORATED FIGURE: B-9 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-5 {Continued) Logged by: JCS Date: 7/25/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 323' MSL i= ..,: w w ii:' ~ u.. ...I ...I w a. 0 0 0:: a. w w w :E :E e:. 0:: !!:. a. < < ~ :::, DESCRIPTION LAB TESTS :I: en en en I-I-§ w ~ ;; en a. > ...I z 5 w a:: :::, w :E C ...I al C al C 61 SANTIAGO FORMATION (continued): Silty sandstone, gray, fine 62 grained, moist, moderately cemented, massive, some iron oxide staining. 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 Total depth: BO feet 82 No groundwater seepage No caving 83 Backfilled: 7/26/01 84 85 86 87 88 89 90 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-10 LOG OF EXPLORATION BORING NO. B-6 Logged by: JCS Date: 7/26/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 265' MSL .::-..,: w w u:-~ u. ..J ..J w 0.. u 0 a:: 0.. !:.. w w w ::!E !:!; a:: !=. 0.. <( <( ~ ::J DESCRIPTION LAB TESTS ::c U) (/) U) I- I-~ w ::.:: iii (/) 0.. > ..J z 0 w 0 ii: ::J w ::!E C ..J C IC C CD 1 COLLUVIUM: Clayey sand with gravel (SC), reddish brown, fine to medium, moist, few cobbles. 2 SANTIAGO FORMATION: Silty sandstone, olive brown, fine grained, moist, 3 weakly to moderately cemented. Remolded clay seam 1/4" thick, brown, soft, irregular surface: N25E/35S. 4 Clay filled fractures 1/4-inch wide, vertical lo subvertical to 11 feet. Maximum Denstiy/ 5 Optimum Moisture Expansion Index 6 5 117 12.1 Clay seam 1/2-inch thick, brown, soft, N20E/51 S. 7 8 9 10 Becomes moderately cemented, massive. 11 12 13 14 15 Oblong zones of sandstone in paleosol, fine grained, friable, iron oxide stained, 16 2 to 3 feet diameter. 17 Randomly oriented clay filled fractures, vertical to subvertical. 18 19 20 21 22 Olive brown, grades downward from fine to coarse, horizontal bedding with iron 23 oxide staining. 24 25 26 Ii 24.8 Shear zone 1-1/2 inches thick, soft clay, steeply dipping: N15E/58N, upper Residual Shear 27 contact of fault zone. 28 29 Shear surface 1/2-inch thick, soft clay, N-S/78W. 30 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-11 LOG OF EXPLORATION BORING NO. B-6 (Continued) Logged by: JCS Date: 7/26/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 265' MSL p t w w u:-~ ..J ..J u w a:: Q.. Q.. e:. w w w :E :E a:: !:!::. Q.. < < i:: ::, DESCRIPTION LAB TESTS :c (I) (I) (I) I-I-~ w :.:: ui (I) Q.. > ..J z 0 w ir ::, w :E C ..J al C al C 31 2 100 23.9 SANTIAGO FORMATION (continued): Claystone, olive green, high plasticity, soft, fissured, sheared. 32 33 34 35 SIity sandstone, brownish yellow, fine grained, moist to wet, iron oxide stained, flat lying, groundwater seepage at 35 feet 36 Shear zone 1 inch thick, soft clay, dipping: N22E/59N, lower 37 contact of fault zone. 38 39 40 5 ■ 114 16.1 41 Grades to massive, strongly cemented, iron oxide stained, mottled, 42 few gypsum veinlets. 43 44 45 46 47 48 Extensively iron oxide stained. 49 50 51 52 53 54 55 56 57 58 59 60 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-12 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-6 (Continued) Logged by: JCS Date: 7/26/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 265' MSL i=" i-: w w ii:" ~ LI. ...I ...I w i:r:: D. D. (.) w w w :!: :!: e:. i:r:: ~ D. <C <C ~ ::, DESCRIPTION LAB TESTS :r: en en en I-I-~ w ~ en en a. 2: ...I z 0 w i:r:: ::, w :!: C ...I m C m C 61 SANTIAGO FORMATION (continued}: Silty sandstone, dusky green, fine grained, moist to wet, moderately indurated, interbedded siltstone. 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 Total depth: 80 feet 82 Groundwater seepage encountered at 35 feet No caving 83 Backfilled: 7/26/01 84 85 86 87 88 89 90 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-13 LOG OF EXPLORATION BORING NO. B-7 Logged by: JCS Date: 7/27/01 Elevation: 269' MSL Method of Drilling: 30-inch diameter bucket auger i=' ..,: w w LL. ..I ..I w a:: 0. 0. w ~ !:. w ::E 0. < :i: rn rn 1/) I-3: w X: 0. > ..I w 0 ii: ::, C ..I C Ill Ill 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 4 ■ 17 18 19 20 21 22 23 24 25 26 5 27 28 29 30 Li:' ~ (.J e:. w a:: ~ ::, I-ci5 rn z 0 w ::E C DESCRIPTION SANTIAGO FORMATION: Silty sandstone, yellowish gray, fine grained, moist, moderately cemented. Clay filled fracture 1/4-inch thick: N10W/64N. Claystone, dusky green, medium plasticity, moist, moderately indurated, iron oxide stained, mottled. Silty sandstone, light olive green, fine grained, moist, moderately cemented. LAB TESTS Sieve Analysis 105 21.7 Fat claystone, light olive brown, high plasticity, moist, moderately Atterberg Limits 112 18.5 indurated, thinly bedded, extensive Iron oxide staining, gypsum veinlets, Direct Shear randomly oriented fractures, tight, 2-to 3-inch spacing. Color change to dusky gray. Silty sandstone, yellowish gray, fine to medium grained, moist, moderately cemented, fossiliferous: shells and shell fragments to 1/2-inch diameter, upper 12 inches strongly cemented. Coarsens downward, fine to medium grained. Claystone, brown, medium plasticity, moist, moderately indurated, gypsum veinlets. Groundwater seepage.------------------------------------------------------- PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-14 LOG OF EXPLORATION BORING NO. B-7 (Continued) Logged by: JCS Date: 7/27/01 Method of DrillinQ: 30-inch diameter bucket auger Elevation: 269' MSL i=-.-: w w ~ ';!. LL ...I ...I UJ 0: a. a. u w ~ e:. UJ !:. w ::E 0: a. cl: ~ ::, DESCRIPTION LAB TESTS ;i: 1/) en en I-I-;: w X: iii en a. .:!: ...I z 0 w 0 0: ::, w ::!!; 0 ...I m C m C 31 SANTIAGO FORMATION (continued): Silty sandstone, olive green, fine grained, moist, moderately cemented, massive, iron oxide stained. 32 33 34 35 36 10 117 15.3 37 38 39 40 41 Total depth: 40 feet 42 Groundwater seepage encountered at 29-1/2 feet No caving 43 Backfilled: 7/27/01 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-15 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-8 Logged by: JCS Date: 7/27/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 299' MSL i=-..,: w w ii:" ~ LL. -I -I w 0:: 0.. 0.. 0 w :5 !:. w ~ w :5 0:: 0.. < < ~ :::, DESCRIPTION LAB TESTS ::c ti) ti) ti) I-I-3: w ~ en ti) 0.. > -I z 0 w 0 ~ :::, w C -I :i: m C m C 1 COLLUVIUM: Silty sand {SM), light brown, fine to medium, dry, loose, roots. 2 3 SANTIAGO FORMATION: Silty sandstone, light brownish gray, fine grained, dry to moist, moderately to strongly cemented, occasional 4 strongly cemented layers up to 12 inches thick. 5 6 7 Graded beds, fine to medium grained, iron oxide staining. 8 9 10 11 12 13 14 15 16 Grades to poorly graded sandstone, fine grained, massive. 17 18 19 20 21 22 23 24 lnterbedded silty sandstone, fine grained, gradational contacts. 25 26 27 28 29 30 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-16 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-8 (Continued) Logged by: JCS Date: 7/27/01 Method of Drilling: 3O-inch diameter bucket auger Elevation: 299' MSL i=-i-: w w ii:' ~ u.. ...I ...I w 0:: a.. a.. CJ w :E :E e.:. w w 0:: !:!::. a.. <( <( ~ ::::, DESCRIPTION LAB TESTS i= (/) (/) (/) I- § w ~ u.i en a.. > ...I z 0 w ii: ::::, w :E Q ...I Q al Q al 31 SANTIAGO FORMATION (continued): Silty sandstone, yellowish gray, fine grained, moist, moderately to strongly cemented, zones of strongly cemented 32 material up to 12 inches thick. 33 34 35 36 37 38 39 40 41 Total depth: 40 feet 42 No groundwater seepage encountered No caving 43 Backfilled: 7/27/01 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-17 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-9 Logged by: JCS Date: 8/13/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 258' MSL i=-~ w w ii:' ~ u. ..J ..J w a. (.) 0 0:: a. w :!: :!: e:.. w w 0:: ~ Q. < < ~ :, DESCRIPTION LAB TESTS :I: ti) ti) ti) I-I-3: w X: ;; ti) a. > ..J z 0 w 0 ii: :, w :!: a ..J a m a m 1 SANTIAGO FORMATION: Silty sandstone, light yellowish brown, fine grained, moist, moderately cemented, massive. 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Shear surface 1/4-inch thick, soft clay, N73W/73S, truncates bedding 22 in sandstone beds above and below, 3-inch thick zone of loose sand along surface. 23 24 25 26 Slight groundwater seepage. 27 28 Sandy siltstone, olive green, moist, moderately indurated. 29 30 PROJECT NO. 0669-001-00 GEOTECHNICS IN CORPORA TED FIGURE: B-18 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-9 (Continued) Logged by: JCS Date: 8/13/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 258' MSL i=' i-: w w Lt. .J .J w 0:: a. a. w w :s :s lb, a. <( <( ::c en en en I-3:: w ~ a. ~ .J w 0 ::::, C .J m C m 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 i'.L' ~ 0 w !:!::. 0:: ~ ::::, I-iii en z 0 w == C DESCRIPTION SANTIAGO FORMATION (continued): Siltstone, dark green, moderately to strongly indurated, tight, blocky fractures 6-to 8-inch spacing, polished surfaces. Irregular erosional contact, load casts, rip up clasts of ciaystone. Claystone, brownish gray, medium plasticity, moist. moderately indurated, thm planar bedding, iron oxide staining, gypsum veinlets. Silty sandstone, grayish brown, fine grained, moist, moderately cemented, iron oxide stained, mottled, gypsum veinlets. Strongly cemented zone 2 feet thick, core barrel used, fossiliferous. 1------------------------------- lnterbedded c!aystone and silty sandstone, dark blue gray, medium plasticity, moderately indurated, thinly bedded, gypsum. 1-------------------------------- Silty sandstone, dark blue gray, fine grained, moderately cemented, massive, thin laminae of black fine sand. PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED LAB TESTS FIGURE: B-19 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-9 (Continued) Logged by: JCS Date: 8/13/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 258' MSL i=' ..: w w ii:' ~ u. ...J ...J w 0. CJ . 0: 0. w w w :2 :ii: e:. n:: !::. 0. < < ~ ::, DESCRIPTION LAB TESTS ::c Cl) Cl) Cl) I-I-== w ~ 0 Cl) 0. > ...J z 0 w 0 ii: ::, w :ii: C ..J C m C ID 61 SANTIAGO FORMATION (continued): Silty sandstone, dark gray, fine grained, massive, groundwater seepage. 62 63 64 65 66 67 68 69 70 71 Strongly cemented zone 2 feet thick, core barrel used. 72 73 74 75 76 77 78 79 80 81 Light gray, fine to medium grained, moist, moderately cemented, massive, layers of iron oxide staining, large cross beds up to 8 inches thick. 82 83 84 85 86 87 Total depth: 90 feet 88 Groundwater seepage encountered at 26-1/2 and 62 feet No caving 89 Backfilled: 8113101 90 PROJECT NO. 0669-001-00 GEOTECHNICS IN CORPORA TED FIGURE: B-20 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-10 Logged by: JCS Date: 9/12/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 260' MSL .=-i-: w w u::-~ u. ...I ...I w 0:: D. D. (.) w w w ::; ::; !:!::. 0:: !:::. a. <( <( ~ :::, DESCRIPTION LAB TESTS ::i: U) U) U) I-I-3: w ~ in U) D. > ...I z 5 w 0 i:2 :::, w ::; Q ...I Q m Q m 1 COLLUVIUM: Silty sand (SM), brown, fine grained, moist, loose, few grave!. 2 3 4 SANTIAGO FORMATION: Silty sandstone, yellow brown, fine to medium grained, moist, moderately cemented, massive, some iron oxide staining. 5 6 7 8 9 10 11 12 13 Light gray, fine grained. 14 15 16 17 18 19 20 21 22 Strongly cemented !ayer approximately 18 inches thick. 23 24 25 26 27 28 29 At 29 feet, groundwater seepage. 30 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-21 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-10 (Continued) Logged by: JCS Date: 9/12/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 260' MSL i=-i,-: w w u:-::,e u.. ..J ..J w a. 0 .. a::: a. w w w :s :s e:. a::: !::. a. < <C ~ :::, DESCRIPTION LAB TESTS :c U) U) u, I-I-;: w ~ en u, 0. 2: ..J z 0 w 0 a::: ::::, w :s C ..J al C m C 31 SANTIAGO FORMATION {continued): Silty sandstone, light gray, fine grained, 32 moist to wet, moderately cemented, massive, iron oxide staining in layers. 33 34 35 36 37 38 39 40 Lean claystone, dark bluish green, medium plasticity, moist. moderately 41 indurated, randomly oriented polished surfaces at 4-to 6-inch spacing, tight. 42 Silty sandstone, dark gray, fine grained, moist, moderately cemented, thin interbeds of coal. 43 44 45 Lean claystone, dark olive gray, medium plasticity, moist, moderately indurated. 46 At 46½ feet, fat clay seam approximately 1/8-inch thick, soft, continuous, 47 flat-lying. 48 49 Silty sandstone, gray, fine grained, moist, moderately cemented, massive. 50 51 52 53 54 55 56 57 58 59 60 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-22 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-10 (Continued) Logged by: JCS Date: 9/12/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 260' MSL p i..: w w ii:" ~ u. ..J ..J w Q. (.) 0 a:: Q. w w w :E :E e:. a:: !:!::. Q. < < ~ :::::, DESCRIPTION LAB TESTS :c en ti) (/) I-I-3: w ~ in ti) a. > ..J z 5 w 0 ii: :::, w :E Q ..J Ill C Ill C 61 SANTIAGO FORMATION (continued): Silty sandstone, gray, fine grained, moist, moderately cemented, massive. 62 63 64 65 66 67 68 69 Stongly cemented layer approximately 2 feet thick. 70 71 72 73 74 75 76 77 78 Total depth: 77 feet 79 Groundwater seepage encountered at 29 feet. No caving 80 Backfilled 9/12/01 81 82 83 84 85 86 87 88 89 90 PROJECT NO. 0669--001-00 GEOTECHNICS INCORPORATED FIGURE: B-23 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-11 Logged by: JCS Date: 9/12/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 263' MSL i= ~ w w u::-~ u. ..J ..J w a. c., .. w 0:: :z; a. e:. w w :z; 0:: !::!::. a. < < ~ :::, DESCRIPTION LAB TESTS :c (/) (/) U) I-I-3: w ::a:: ui (/) a. > ..J z 0 w 0 ii: :::, w :z; C ..J C ID C ID 1 COLLUVIUM: Clayey sand (SC), brown, fine, moist, loose. 2 3 4 Remolded clay seam, soft, 1/4-inch thick oriented: N85E/27N. 5 SANTIAGO FORMATION: Silty sandstone, light yellow brown, fine grained, moist, moderately cemented, massive, some iron oxide staining. 6 7 8 9 10 Pale yellow. 11 12 13 14 15 16 Strongly cemented layer approximately 2 feet thick. 17 18 19 20 21 22 23 24 25 lnterbeds of claystone, green, medium plasticity, moist, moderately indurated, 2 to 3 inches thick. 26 27 28 29 30 PROJECT NO. 0669-001-00 GEOTECHNICS INCORPORATED FIGURE: B-24 LOG OF EXPLORATION BORING NO. B-11 (Continued} Logged by: JCS Date: 9/12/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 263' MSL .=-t: w w ..J .J LIJ 0::: D. D. LIJ :I: ~ LIJ !:!:. D. < ::c Ill Cl) Ill I-~ w ::.:: D. > .J w 0 1iE :::, 0 .J C co co 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 ~ '/!. (.) e:. w 0::: ~ :::, I-en Cl) z 0 w === C DESCRIPTION SANTIAGO FORMATION (continued): Silty sandstone, light yellow brown, fine to medium grained, moist, moderately cemented, massive, some iron oxide staining. At 39 feet, groundwater seepage. Fat claystone, olive green, high plasticity, moist, moderately indurated. Randomly oriented polished surfaces, 2-to 4-inch spacing. At 49 feet, fat clay seam, soft, continuous, oriented: N30E/13N, 1/4 inch thick. ····························---·······················································································································"'''''''''''''''''''''''''''''''' Silty sandstone, gray, fine grained, moist, moderately cemented, massive, some iron oxide staining. PROJECT NO. osss-001-ooGEOTECHNICS INCORPORATED LAB TESTS FIGURE: B-25 I I I I I I I I I I I I I I I I I I I LOG OF EXPLORATION BORING NO. B-11 (Continued) Logged by: JCS Date: 9/12/01 Method of Drilling: 30-inch diameter bucket auger Elevation: 263' MSL i=' i-= w w ii:' ~ LI. ...I ...I (.) 0 w 0:: a.. a.. w :i: e:. w w :i: 0:: !:. a.. < < ~ ::, DESCRIPTION LAB TESTS :c rn rn (/) I-I-§ w ~ en (/) a.. ~ ...I z 0 w 0:: ::, w :i: C ...I C 111 C m 61 SANTIAGO FORMATION {continued): Silty sandstone, gray, fine grained, moist, moderately cemented, massive, some iron oxide staining. 62 63 64 65 66 67 68 69 Total depth: 68 feet 70 Groundwater seepage encountered at 39 feet. No caving 71 Backfilled: 9/12/01 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 PROJECT No. oss9-001--00GEOTECHNICS INCORPORATED FIGURE: B-26 I I I I I I I I I I I I I I I I I I I APPENDIXC LABORATORY TESTING Selected soil samples encountered during the investigation were tested using generally accepted testing standards. The soils selected for testing are believed to be generally representative of the materials encountered during the investigation at the site. However, variations may occur in the soils at the site, and the materials tested may not be representative of the materials encountered during construction. Laboratory testing was conducted in a manner consistent with that level of care and skill ordinarily exercised by members of the profession currently practicing under similar conditions and in same locality. No other warranty, expressed or implied, is made as to the correctness or serviceability of the test results or the conclusions derived from these tests. Where a specific laboratory test method has been referenced, such as ASTM or Caltrans, the reference applies only to the specified laboratory test method and not to associated referenced test method(s) or practices, and the test method referenced has been used only as a guidance document for the general performance of the test and not as a "Test Standard.'' A listing of the tests performed follows: Classification: Soils were classified visually according to the Unified Soil Classification System. Visual classification was supplemented by laboratory testing of selected samples and classification in accordance with ASTM D 2487. The soil classifications are shown on the boring logs in AppendixB. In-Situ Moisture/Density: The in-place moisture contents and dry unit weights of selected relatively undisturbed samples were evaluated in general accordance withASTM test method D 2937 and 2216. The dry unit weights and moisture contents are shown on the boring logs in Appendix B. Particle Size Analysis: Particle size analyses were performed in general accordance with the laboratory procedures outlined in ASTM test method D 422. The results are summarized in Figures C-1 and C-2. Atterbem Limits: ASTM test method D4318-93 was used to estimate the liquid limit, plastic limit, and plasticity index of selected samples. The results are summarized on Figures C-1 and C-2. Maximum Density/Optimum Moisture: The maximum dry density and optimum moisture content of a selected soil sample was estimated in general accordance with the laboratory procedures outlined in ASTM test method D 1557-91, modified Proctor. The test results are summarized in Figure C-3. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I APPE1'"'DIX C LABORATORY TESTING (continued) Sulfate Content: To assess the potential for reactivity with below grade concrete, a selected soil sample was tested for water soluble sulfate content. The water soluble sulfate was e~-tracted from the soil under vacuum using a I 0: I (water to dry soil) dilution ratio. The extracted solution was then tested for water soluble sulfate in general accordance with ASTivI D 516. The results are presented on Figure C-3. pH and Resistivity: The pH and resistivity of a selected sample were evaluated in general accordance with CAL TRANS method 643. The results are listed in Figure C-3. Expansion Index: The expansion potential of a selected soil sample was characterized by using ASTM test method D 4829-88. Figure C-4 provides the results of the testing. R-Value: R-Value testing was performed on a selected bulk sample to evaluate the strength of the on-site materials for use as pavement subgrade materials in general accordance "\\ith the laboratory procedures outlined in ASTh1 test method D 2844. The results are presented on Figure C-4. Direct Shear: The shear strengths of selected soil samples were assessed through direct shear testing performed in general accordance with the laboratory procedures outlined in AST~:1 test method D 3080. The results are summarized in Figures C-5 through C-7. -------------Geotechnics Incorporated ------------- I I I I I I I I I I I I I I I I I I I MAXIMUM DENSITY/OPTIMUM MOISTURE CONTENT (ASTM Dl557-91) S.Al\lPLE DESCRIPTION B-6 @ 4-6' Olive brm,vn silty sandstone '·SM" MAXIMUM DENSITY (pcf) 114½ pH, RESISTIVITY, AND SULFATE SAMPLE B-5@4-6' WATER-SOLUBLE SULFATE CONTENT (% of Dry Soil Weight) (ASTMD516) 0.02 pH (CAL TRANS 643) 5.33 a~ Geotechnics Incorporated LABORATORY TEST RESULTS OPTIMUM MOISTURE (%) 11½ RESISTIVITY (ohm-cm) (CAL TRANS 643) 837 Project No. 0669-001-00 Document No. 1-0805 FIGURE C-3 I I I I I I I I I I I I I I I I I I I APPENDIXD SEISMICITY Seismic analysis v,ras conducted for the subject site in order to develop parameters for structural design, and well as input parameters for the slope stability analysis. This appendix presents the raw data from our analysis from three commercially available computer programs, EQFAULT, EQSEARCH andFRISKSP (Blake, 1998). All three analyses used the same published attenuation relationship for stiff soil sites (Idriss, 1994 ). EOFAULT: The program EQFAULT was used to develop the deterministic peak ground acceleration parameters presented in the text of this report. EOSEARCH: The program EQSEARCH was used to generate a table of estimated characteristics of nearby seismic events which were recorded bernreen 1800 and 1999. This table is presented ,vithin Appendix F, and shows the epicenters, magnitudes, and dates of these nearby earthquakes, along with the estimated peak ground acceleration for the site, and a recurrence curYe generated from the data. The data from EQSEARCH is also presented in graphical form in this appendix. Note that the circle shown in this figure represents a 100 km radius around the site. FRISKSP: The program FRISKSP was used perform a probabilistic analysis of seismicity at the subject site based on the characteristic earthquake distribution ofY oungs and Coppersmith ( 1985). The results are also presented within Appendix F. The probabilistic analysis was used to define the Upper Bound and Ma'{].IDum Probable Earthquakes for the site for use in structural design. Note that the graphs do not incorporate :Magnitude Weighting Factors, and represent the probabilistic values presented in the text of this report. I I I I I I I I I I I I I I I I I I I APPENDIXD SLOPE STABILITY ANALYSIS The gross stability of the proposed slopes was analyzed using PCST ABL5 software and average ultimate shear strengths as summarized below. The shear strengths of the cohesive soils were increased by an appropriate amount for analysis of short-term seismic loading. The following figures include analyses of the existing slopes, the proposed slopes, and the proposed slopes with remedial grading for partial removal of the fault gouge or clay seam. The critical failure surfaces generated, and corresponding safety factors, are presented in the follov.ring figures of this appendix. Total Unit C MATERIAL Weight q, (pcf) (psi) (degrees) Compacted Fill 135 100 34 Colluvium/ Alluvium 132 0 28 Silty Sandstone 124 0 38 Fat Claystone 128 0 22 Remolded Clay 1 (up to 30' of 123 0 10 overburden) Remolded Clay 2 (benveen 30' and 40' 123 0 13 of overburden) Remolded Clay 3 (greater than 40' of 123 0 16 overburden) Claystone 4 (fault zone) 123 0 20 The gross, static stability of the existing and proposed slopes was evaluated with groundwater levels as encountered, and as anticipated for the post-graded condition, respectively (F.S. > 1.5). The dynamic stability of selected slopes (Sections B-B' and G-G') were evaluated using a pseudo- static analysis using horizontal and vertical seismic coefficients of 0.15g (F.S. > 1.0). General analyses were conducted using Bishop's circular surface and sliding block search routines. The analysis indicates that the proposed slopes are generally stable and, in most cases, meet or exceed industry-standard safety factors of 1.5 and 1.0 for static and pseudo-static stability, respectively.