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Home My WebLink AboutCDP 01-35; PATEL RESIDENCE; LIMITED GEOTECHNICAL INVESTIGATION; 2000-03-10I· ·I.·· . I I I I ! ' l l 1/ ; I I I I I I I I I I I I I I I I I I I I I I .1 I:'..-. I I. I I I I I I I I I I I I I. . . . . . . ' . . . ~ . ., ~ . ' . .. . .. . . Limited Geotechnical Investigation PROPOSED SINGLE FAMILY RESIDENCE 1280 HOOVER STREET . CARLSBAD, CALIFORNIA 1280 Hoover Street Carlsbad, California . ··. Prepared for: Dr. Shantu Patel C/0 Bridge Motor Inn 1103 North Coast ffigh:way Oceanside~ CA 920S4 -Prepared by: · -RECEIVED. O·C 1 ·1 8 ·2002 ENGINEER\NG OEPARTMENT Testing Engineers -San Diego, Inc. 7895 Convoy Cc;mrt, Suite 18, San Diego, California 92111 Proj~ct No. 2000-080 March 10, 2000 ·1 I I .. I I I I I I I I I I I I Testing Engi·neers -San Diego, Inc. Dr. Shantu Patel ··c10 Bridge Mqtor Inn . 1103 North Coast Highway Oceanside, California 92054 Subject: Project: Limited Geotechnical Investigation Proposed Single-Family Residence 1280 Hoover Street Carlsbad, California Dear Dr. Patel: Established 1946 March 24, 2000 Project No. 2000-080 In accordance with your request, Testing Engineers-San Diego, Inc. has conducted a Lµnited Geotechnical Investigation at the referenced site in Carlsbad, California. The attached report discusses the ·geotechnical aspects of the project and provides recommendations for the proposed . development. Our subsurface investigation has found that the propo'sed re~id~ntial building pad is underlain by a one to two-foot lay~r of topsoil over dense terrace deposits to tb,e maximum explored depth of eight (8) feet. We conclude that the development of the proposed residence is geotechnically feasible based upon the existing soil conditions* and provided the recommendations contained herein .are implemented in the design and construction. Testing Engineers-San Diego appreciates the opportunity to be of assistance to you on this project and welcome the oppo:t:tunity to continue our role as geotecbnical consultants. Should you have any questions regarding the contents of this report, please do not hesitate to contact us. en N. Bradley, CEG 1 ~ .... ---~. . ~~ ... P . . 1 G 1 . ,,. .. ,,;; ... ·• ·~ G' •. ,, nnc1pa eo og1st · I/'~<-\\ .._.., ,;.;~".--~"% ((fi~~~li\:l,·, 162:~1\,, ~ \ ~ .• ,,,. i'/11' , q Ew~1res .. 1Eti2L •:'/ i -.,/•' I" "fl!' ' 11J',>; .. /'.,.i}? f s . · -<fj£'c~(f/J)I ~~~A' .1're5ting Engineers· San Diego, Inc., 7895 Convoy Court, Suite 18' San Diego, CA.92111 [858) 715-5800 Fax [858)"'715-5810 I I I 1. I I I I I I I I I I· I I :I I· I TABLE OF CONTENTS INTRODUCTION General ........... : ........................................................................................ 1 PUI.,ose · · · · · · · · 1 'l"' .............. · ••• ; ••••••••••••••••••••••••••••••••••••••••••••••••• ·-· .............................. . Scope of Serv1ces ........................... : ........ ; .. ~ .......... : .................................... l • ~ • • • • •• • • • < ' • • • PROJECT BACKGROUND S. D . . . 2 1te escr1pt1on .................. , ......................................................... · · . · · · · · · · · · · · · Proposed Development ................................................................................ 2 SITE INVESTIGATION AND LABORATORY TESTING Subsurface Exploration ................................................................................. 2 Laboratory Testing Program ............................... : .......................................... 2 GEOLOGY Geologic Setting ............................................................................................ 3 Site Stratigraphy .......................................................................................... 3 GEOTECHNICAL EVALUATION General Conclusio~ ................. .' ........................................................... · ...... 3 . Compressible Soils ....................................................................................... 4 Expansive_ Soils ...................... : ............................ ; ..... ,. ..................... · .............. 4 Groundwater.-............................ : ...................... : .. · ...................................... 4 S .. D . C. . · 4 e1sm1c es1gn r1ter1a ............................................................................... . Liquefaction ........................................ , ...................................... , .............. 5 Permanent Slopes .......................................................................................... 5 Temporary Slop~s ...................................................................................... 5 GRADING AND EARTHWORK RECOMMENDATIONS General .................................................................................................... 5 Cl~aring and Grubbing ................................................................................ 5 Structural I;rnprovement of Soils ..................................................................... 5 Transitions Between Cut & Fill ...................................................................... 6 Method and Criteria of Compaction: ... : .................... ; ........................................ 6 Placement.of Oversized Rock ........................ : ...................... ~ ............. .-. .-........... 7 Erosion and Siltation .. .' ..... .' ...................... ; ........................................ , ............ 7 Standard Grading Guidelines ................................. , ........................................ 7 FOUNDATION AND SLAB RECOMMENDATIONS General ................................................................................................... 7 • l ~ \ f Conventional Foundations ..................... , ...................................................... 8 Conventional Slabs-on-Grade ........................................................................... 9 Settlen1ent ...................................................................................... : .............. 9 Presaturation of Slab Subgrade ....................................................................... 9 :I I I '.1· :I I I I 1· :·1. I I I I I I I I I TABLE OF CONTENTS (continued) ADDITIONAL RECOMMENDATIONS Retaining Walls .......................................................................................... 9 Pavement$ .. · ....... ; ......... ; ............................. · .. ; ... · ......................................... 10 Trench Backfill. .......................... ; ......... -................................................... 11 ···surface D1~ainage .......... : ... :: .. :, ..... : ... :.: ........ : ....... : ........... : ......................... 11 Foundation Review . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 CLOSURE Limits of Investigation ...... .-......................................................................... 12 Additional Services .. .. . .. . . . . . .. .. . .. . .. . . .. .. .. . . .. • .. .. .. . .. . . .. . . . . . . . . . .. . .. . .. .. .. .. . . .. . .. . .. . . 12 FIGURES Figure 1 -Site Location Map Figure 2 -Plot Plan · APPENDICES Appendix A -References Appendix B -Field Exploration Logs Appendix C -Laboratory Test Results I . I I I I I I I I I I I I I 1. I I I I I I INTRODUCTION General This report presents the findings and conclusions of a Limited Geotechnical Investigation for the ·proposed construction of a single family residence to be located on the west side of Hoover Street in Carlsbad, California. The Site Location Map, Figure 1, follows the text of this report. The investigation basically consisted of field reconnaissance and geologic mapping, subsurface exploration, laboratory testing and engineering/geological evaluation of the obtained information. Purpose The purpose of the investigation was to evaluate the surface and subsurface conditions of the proposed area of development and provide recommendations regarding design of suitable foundation systems for the proposed residence, along with other site development criteria. Scope of Services The following scope of services were conducted during the development of this report: O. ... Site reconnaissance an~ review of published geologic, seismological and geotechnical reports and maps pertinent to the project area; · O Excavation of four (4) test pits within the limits of the proposed area of development. The test pits were logged by our Staff Geologist. A Plot Plan, Figure 2 indicates the approximate test pit locations. Detailed Exploration Logs are contained in Appendix B; O Collection of representative soil samples at selected depths. The obtained samples were sealed in moisture-resistant containers and transported to the laboratory for subsequent analysis; O Laboratory testing of samples representative of the soils encountered during the field investigation; . · O. Geologic and engineering analysis of tile field. and laboratory data which provided the basis for our conclusions and recommendations; O Production of this rep5>rt which summarizes the results of the above analysis and presents our findings and recommendations for site development. SFR: Hoover Street* Limited Geotechnical Investigation* Carlsbad. CA * (858) 715-5800 * Project No. 00-080 * March 24, 2000 1 of 12 :1 I I I I I I. I I ·I I I I I I I I ·I I. PROJECT BACKGROUND Site Description The subject site is a rectangular..,shaped_ residential lot located on the west side of Hoover Street, in the ·city of Carlsbad; California. Tile-project location is shown on Figure 1, Site Location Map.· The site encompasses an area of approximately one (1) acre with a moderate west-sloping natural terrain. Vegetation consisted of grass, shrub, ice plant and few trees. The subject parcel is bordered by similar residential developments. Proposed Development Based on the plans prepared by Sullivan Development of Carlsbad, California, the proposed development will include a single-story structure to be utilized as a residence. A driveway will access the property along the south-east side of the proposed residence from Hoover Street. The Plot Plan, Figure 2, provides a layout of the proposed development. SITE INVESTIGATION AND LABORATORY TESTING Subsurface Exploration · The site investigation, consisting of surficial reconnaissance and subsurface exploration, was conducted on March 1,. 2000. Subsurface exploration was conducted by test pits excavated with a Case 5801 backhoe equipped with a 24-inch bucket. The purpose of the test pit excavations was to evaluate the condition of the soils in the proposed area of development. A total of four ( 4) te$t pits were completed to depths ranging from approximately 6 to 8 feet below the existing ground surface. The test pits were logged in the field by the Staff Geologist. Representative samples were collected, sealed in moisture-resistant containers, and transported to the laboratory for subsequent testing. Detailed descriptions of the encountered subsurface materials are provided in the Site Stratigraphy section of this report. The test pit locations are indicated on the Plot Plan, Figure 2. Appendix B contains the Field Exploration Logs. Laboratory Testing Program In addition to the field exploration, a laboratory testing program was conducted to establish the pertinent engineering characteristics of the foundation materials. The laboratory testing program included visual classification,, particle size analysis, direct sJ:iear, expansion index and maximum dry density and optimum moisture content tests. All laboratory tests were performed in general accordance with applicable ASTM standard specifications or other accepted test methods. Appendix C provides a summary of test procedures and results. SFR Hoover Street* Limited Geotechnical Investigation* Carlsbad, CA * (858) 715-5800 * Project No. 00-080 * March 24, 2000 · 2 of 12 I I I I. I I I I I I- I I I I I I I I GEOLOGY . Geologic Setting . The subject _site is located within tbe southe:r;n portion of what is known as the Peninsular Ranges Geomorphic Province of California. The coastal areas _of the province in Carlsbad are typically made up of Pleistocene marine terrace deposits ( Qm'). Site. Stratigraphy The subsurface descriptions provided are interpreted from conditions exposed during the field investigation and/or inferred from the geologic literature. As such, all of the subsurface conditions may not be represented. Detailed descriptions of the subsurface materials encountered during the field investigation are presented on the Exploration Logs provided in Appendix B of this report. The following paragraphs provide general descriptions of the encountered soil types. Topsoil Topsoil is tbe surficial soil material that mantles the ground, usually containing roots and other organic materials which supports vegetation. Topsoil observed in each of the test pits was approximately 1.0 to 2.0 feet thick and consisted of dark brown, poorly graded sand that was moist, loose and :porous in consistency with ~or amounts of organics (roots and. rootlets). Marine Terrace Deposits ( Om ) Terrace deposits were observed below the topsoil horizon. They generally consisted of reddish brown, poorly graded sand. The moisture content ranged from damp to very moist and the materials were medium dense to very dense in consistency. Well indurated sandstone and conglomerate were encountered approximately three feet below existing ground. These soils were difficult to excavate. GEOTECHNICAL EVALUATION General Conclusions Based' on our investigation and evaluation of the collected information, we conclude that the proposed structural development is feasible from ~ geotechnical standpoint provided the recommendations contained in this report will be properly implemented during structural development. Based on the non-expansive nature of the granular near-surface soils, it is our opinion that the building pads may be constructed using the ona.site materials. In order to provide a uniform ~upport for the structures, overexcavation ap.d recompaction of tbe structural portions of the building pads will be required. The foundations may consist of reinforced continuous footings with conventional reinforced slabs. Recommendations and criteria for foundation design are SFR Hoover Street* Limited Geotechnical Investi ation * Carlsbad CA* 858 715-5800 * Pro·ect No. 00-080 * March 24 2000 3 o 12 I I ·.I I .1 I .I I I I I I I I I I i I I I I contained in the Foundation and Slab Recommendations section of this report. Compressible Soils Our field observations and testing indicate low compre~sibility within the sedimentary bedrock that 1JJ:1.derlies the entire site.· However, loose topsoil was typically .encountered to a depth of approximately 2.0 feet below surface grades. In general, the surficial topsoil is compressible. Due to the potential for soil compression upon loading, remedial grading of these near-surface soils (including overexcavation and recompaction) will be required. Following implementation of the earthwork recommendations presented herein, the potential for soil compression resulting from the new development has been estimated to be low. The low- settlement assessment assumes a well-planned and maintained site drainage system. Recommendations regarding mitigation by earthwork construction are presented in the Grading and Earthwork Recommendations section of this report. Expansive Soils The underlying soils consisting of poorly graded sand exhibit a very low potential for expansion. An Expansion Index of zero was obtained from the soils .sample tested. Groundwater Static groundwater was not encountered within the depths of our explorations. In general, it is anticipated that groundwater is generally greater than 100 feet below ground surface in the vicinity of the subject site. Seismic Design Criteria A review of the active fault maps pertaining to the site indicates the existence of the Newport'- lnglewood Fault Zone approximately seven (7) km west of the subject site. Ground shaking from . this fault and the other major active faults in the region is the most likely event affecting the site. The proposed building should be designed in accordance with seismic design requirements of the 1997 edition of the Uniform Building Code or the Structural Engineers Association of California using the following criteria: Parameter Value UBC Reference Seismic ·zone Factor, Z 0.4 Table 16-I · Soil Profile Type SD Table 16-J Seismic Coefficient, Ca 0.44 Table 16-Q Seismic Coefficient, Cv 0.70 Table 16-R Near-Source Factor, Na 1.0 Table 16-S Near-Source Factor, Nv 1.1 Table 16-T Seismic Source B Table 16-U SFR Hoover Street* Limited Geotechnical Investigation* Carlsbad, CA* (858) 715-5800 * Project No. 00-080 * March 24, 2000 · 4 of 12 I I I 1 .. 1· I I .I I ·1 I I I I· __ I I I I I Liquefaction Based on the absence of shallow groundwater and consistency of the underlying soils, it is our opinion that the potential for liquefaction is very low. Permanent Slopes Permanent cut and fill slopes are anticipated to be less than 5 feet in height and may be ~onstructed at a II1aximum slope ratio of 2:1 ( hor. to vert.) to the heights indicated on the plans. Slopes constructed in such a manner are anticipated to be grossly stable. Due to the granular nature of the on-site soil materials, surficial erosion is a common problem. It is recommended that drought resistant vegetation be planted on the slope faces as soon as practical to enhance the stability of the slope surfaces. Temporary Slopes For the excavation of foundation or utility trenches, temporary vertical cuts to a maximum of 4 feet may be constructed in fill or natural soil. Any temporary cuts beyond the above height constraints should be shored or further laid back following a 1:1 ( hor. to vert ) slope ratio. OSHA guidelines for trench excavation safety should be implemented during construction. GRADING AND EARTHWORK RECOMMENDATIONS General Based upon our understanding of the preliminary plans and the information obtained during the field investigation, we anticipate that structures will be founded on continuous footings, which are supported entirely by properly compacted fill. The following grading and earthwork recort1mendations are based upon the limited geotechnical investigation performed, and should be verified during construction by our field representative. Clearing and Grubbing All areas to be _graded or to receive fill and/or structures should be cleared of vegetation. Vegetation and the debris froni the clearing operations should be properly disposed of off-site. The area should be thoroughly inspected for any possible buried objects, which need to be rerouted or removed prior to the inception of, or during grading. All holes, trenches, or pockets left by the removal of these objects should be properly backfilled with compacted fill materials as recommended in the Method and Criteria of Compaction section of this report. Structural Improvement of Soils Information obtained from our field and laboratory analysis indicates that loose topsoil covers portions of the site to depths ranging from approxiinately 1.0 to 2.0 feet. These loose surficial soils are susceptible to settlement upon loading. Based upon the soil characteristics, we SFR Hoover Street* Limited Geotechnical Investi ation * Carlsbad CA* 858 7-15-5800 * Pro·ect No. 00-080 * March 24 2000 s·o 12 I I I :1 I I I I I I I I I I I I I I I recommend the following: * * * All topsoil or other loose natural soils should be completely removed as described herein from areas which are planned to receive compacted fills and/or structural improvements. The bottom of the removal area should expose competent materials as approved by TESD geotechriical representative. Prior to the placement of new fill, ·the bottom of the removal area should be scarified a minimum depth of at least 6 inches, :moisture.:.conditioned from . 0 to 2 percent above the optimum moisture content, and then recompacted to at least 90 percent relative compaction {ASTM D-1557 test method). Overexcavation should be completed for the structural building pad to a minimum depth of 2 feet below the bottom of the proposed footing or 3-.0 feet below surface grade, whichever is greater. The limit of the required area of overexcavation should be extended a minimum of 5 feet laterally beyond the perimeter footing (building footprint). For non-structural areas, such as driveways, we recommend overexcavation to a minimum depth of 2 feet below existing grade or 1.5 feet below proposed sub grade, whichever is greater. Soils utilized as fill should be moisture-conditioned and recompacted in conformance with the fo~lowing Method and ~riteria of Compaction section of this report. The depth ·and extent of any overexcavation and recompaction should be evaluated in the field by a repr~sentative of TESD. Transitions Between Cut and Fill Proposed structures are anticipated to be founded entirely in properly compacted fill. Cut to fill transitions below the proposed structures should be completely eliminated during the earthwork construction as required in the previous section. Method and Criteria of Compaction Compacted fills should consist of approved soil material, free of trash debris, roots, vegetation or other deleterious materials. Fill soils should.be compacted by suitable compaction equipment in uniform loose lifts. of 6 to 8 inches. Unless otherwise specified, all soils subjected to recompaction should be moisture-conditioned within 2 percent of the optimum moisture content and recompacted to at least 90 percent relative compaction per ASTM test method D-1557. The on-site soils, after being processed to delete the aforementioned deleterious materials, may be used for recompaction purposes. Should any importation of fill be planned, the intended import source(s) should be evaluated and apprQyed by TESD prior to delivery to the site. Care should be taken to ensure that these soils are not detrimentally expansive. SFR Hoover Street* Limited Geotechnical Investigation* Carlsbad. CA * (858) 715-5800 * Project No. 00-080 * March 24, 2000 · 6 of 12 I I 1· I I. I I I I I I I I I I I Placement of Oversized Rock All materials for capping the structural building pads should be free of rocks and debris in excess of 3-inch dimension. Select fill should extend a minimum of 5 feet laterally outside the structural footprint: ·Material up to 12-inch dimension· may be placed between 3 and 10 feet from finish grades, but must remain at least 10 feet laterally from the face of permanent slopes and should also not be placed within the alignment of proposed utilities. Although we do not anticipate earthwork construction to create oversized material from 12 to 48 inches in dimension, if encountered, it may be placed in approved non-structural fill areas. The oversized material should be placed in windrows surrounded by granular fill. The rock windrows should be flooded with water to. facilitate filling of voids. Care should be taken to avoid nesting of oversize rocks and no large rock should be placed within 10 feet of any slope face. The non-structural rockfill should be capped with a minimum 3 feet of fill containing no rocks greater than 6-inch dimension. Erosion and Siltation Due to the granular characteristics of the on-site soils, areas of recent grading or exposed ground J:I¥lY be subje~t to erosion. During construction, surface water should be controlled via berms, ·sandbags, siltation basins, positiv(; surface grades, or other niethod to avoid damage to the finish work or adjoining properties. The contractor should take measures to prevent erosion of graded areas until such time as permanent dramage and erosion control measures have been installed. After completion of grading, all excavated surfaces should exhibit positive drainage and eliminate areas where water might pond. Standard Grading Guidelines Grading and earthwork should be conducted in accordance with the standard-of-practice methods for tp.is local, the guidelines of the current edition of the Uniform Building Code, and the requirements of the jurisdictional agency. Where the information provided in the geotechnical report differs from the Standard Grading Guidelines, the requirements outlined in the report shall govern. FOUNDATION AND SLAB RECOl\iMENl>ATIONS General The foundation design recommendations herein are "minimums" in keeping with the current standard-of-practice. They do not preclude more restrictive criteria of the governing agencies or structural considerations. The Structural Engineer should evaluate the foundation configurations and reinforcement requirements for structural loading, concrete shrinkage and temperature stresses. All design and site development criteria should conform to the minimum design requirements provided in the current edition of the Uniform Building Code (UBC). SFR Hoover Street* Limited Geotechnical Investigation* Carlsbad, CA * (858) 715-5800 * Project No. 00-080 * March 24, 2000 7 of 12 I I I I . I I I _·I I I I I I I I I Conventional Foundations Conventional continuous footings are suitable for support of the planned residential building and garage. Footings for the structures should be founded entirely in properly compacted fill soil. The footing dimensions, reinforcement, and other structural criteria presented below are based on geotechnical considerations and are not intended to be in lieu of requirements of the Structural Engineer. --. -- Footing Dimensions Exterior footings for the single-story structure should be embedded a minimum of 12 inches below ·the lowest adjacent grade and have a minimum width of 12 inches. Excavations should be trimmed "neat", square and level, with no loose debris prior to concrete placement. Interior footings should also be embedded a minimum of 12 inches at a minimum width of 12 inches . Reinforcement It is recommended that all exterior footings be reinforced with a minimum of two No. 4 steel reinforcing bars placed horizontally in the footing, one near the top and one near the bottom. Interior footings should be similarly reinforced wi~ two No. 4 tebars. The above reinforcement is based on soil characteristics and is not intended to supersede requirements of the structural engineer. Allowable Bearing Capacity A soil bearing pressure of 3500psf may be utilized for continuous footings founded in properly compacted fill. The soil bearing pressure may be increased by 400 and 250 psf for each additional 6 inch increment of depth and width respectively. For settlement considerations, the maximum allowable bearing capacity should not exceed 4,000 psf for footings constructed into compacted fill. Lateral Earth Resistance Lateral loads against foundations or retaining st:r~uctures may be resisted by friction between the bottom of the footing and the supporting soil. An allowable friction coefficient of 0.40 may be utilized in the foundation design. Alternatively, a_n allowable passive earth pressure of 335psf/ft (335pcf EPP) may be used. The values for frictional and passive resistance incorporate a factor- of-safety equal to 1.5. In order to utilize the given values, footings :piust be poured "tight" against competent soils. Should frictional resistance and passive pressure be used conjunctively, the passive pressure value should be reduced by one-half. A one-third increase in the lateral resistance may be considered for transient loads (wind/seismic). SFR Hoover Street* Limited.Geotechnical Investi ation * Carlsbad CA* 858 715-5800 * Pro"ect No. 00-080 * March 24 2000 8 o 12 I I I .. I. ·I I I I I I ,I I I I I I I Slabs-on-Grade Conventional interior slabs should be a net 4 inches thick. The slabs should be underlain by a moisture barrier consisting of a minimum of 2 inches of clean sand and 10-mil visqueen sheet. . Moisture-s~nsitive slabs (with tile, linoleum or carpet coverings) should be further underlain (below visqueen) by a ntlnhnum 2 ... inch thick layer of free-draining coarse sand, gravel or. crushed rock: Reinforcement for ·the residential structure and garage should consist of a· minimum of 6 X 6 -10/10 welded wire fabric (WWF) or No. 3 rebar on 24-inch centers. Reinforcement should be located at or slightly above mid-height within the slab section. Reinforcement for actual loading conditions should be as required by the structural engineer. Settlemeiit While subjected to structural loading, a differential settlement up to one-quarter inch should be anticipated, with corresponding total settlement up to one half-inch across the structural span. The values for structure adjustment assume that compressible topsoil is completely removed within the structural prism; and that proper surface drainage is implemented such that the subsoil moisture content is maintained relatively constant. Pr~aturation of Slab Subgrade Due to the granular nature of the surticial soils at this site, pre-soaking of the subgrade prior to. concrete placement is not required. However, it is recommended that subgrade soil in areas to receive concrete be watered prior to concrete placement. The intention of subgrade moistening is to mitigate any drying shrinkage, which may occur between the time of grading and slab construction. ADDITIONAL RECOMMENDATIONS Retaining Walls Cantilevered retaining walls should be designed for an "active" lateral earth pressure of 38 psf/ft (38 pcf EPP) for approved granular .backfill and level backfill conditions. Where cantilevered walls ~upport 2: 1 (hor:vert) sloping backfill, the equivalent active flµid pressure should be increased to 58 pcf. Cantilever walls subject to uniform surcharge loads should be designed for an additional uniform lateral pressure equal to one-third (1/3) the anticipated surcharge pressure. Restrained walls should be designed utilizing an "at-rest" earth pressure of 58 psf/ft (58 pcf EPP) for approved granular and level backfill. Restrained walls subject to uniform surcharge loads should be designed for an additional uniform lateral pressure equal to one-half (1/2) the anticipated surcharge. · Retaining wall footings should be embedded a minimum of 18 inches below the lowest adjacent grade. Retaining walls that are to be located neat the top of slopes should be designed to allow a .minimum daylight distance of 7 feet laterally from the outside edge of the footing to the slope SFR Hoover Street* Limited Geotechnical Investigation* Carlsbad, CA *·(858) 7.15-5800 * Project No. 00-080 * March 24, 2000 · 9 of 12 I I I 1· I I .1 I I :1 1. ·1 ·1 ·1· :1 I I I face. Soil design criteria, such as bearing capacity, passive earth pressure and sliding resistance as recommended under the Foundation and Slab Recommendations section, may be incorporated into the retaining .wall design .. The design and location gf retaining walls should be reviewed by SAGE for confotniance with our recommendatiOIJ.$. Footings should be reinforced as recommended by the structural engineer and appropriate back drainage provided to avoid excessive hydrostatic wa.11 pressures. As a minimum we recommend a fabric-wrapped crushed rock and perforated pipe system. At .least 2 cubic feet per linear foot of free-drainage crushed rock should be provided. The remaining wall backfill should consist of approved granular material. This fill material should be compacted to a minimum relative compaction of 90 percent as determined by ASTM D-1557 test method. Flooding or jetting of baclctill should not be permitted. Granular backfill should be capped with 18 inches (minimum) of relativeJy impervious fill to seal the backfill and prevent saturation. It should be noted that the use of heavy compaction equipment in close proximity to retaining structures can result in wall pressures exceeding design values and corresponding wall movement greater than that associated with active or at-rest conditions. In this regard, the contractor should take appropriate precautions during the backfill placement. 'Pavements The following presents preliminary recommendations for flexible asphalt and rigid concrete pavements. The pavement section requirements have been prepared based on our evaluation of the on-site soils and standard pavement design procedures. The recommendations are not intended to supersede stricter requirements posed by the jurisdictional agency. Asphalt Pavements (AC) It is recommended that the constructed pavement subgtade should be evaluated and tested prior to asphalt placement in order to verify the assumed R-value and/or modify the design sections presented. The R-value of the on-,site soils i$ estimated to be 50 for sandy soil excavated from the decomposed-bedrock. Based on an R-value of 50, we offer the following preliminary pavement design sections. The actual design and adoption relative to allowable road gradients should be developed by the civil designer based on jurisdictional requirements. Traffic Index Recommended Pavement Section Comments 4.5 3.0" AC on 4.0" Class 2 AB Driveway The subgrade soils for the proposed driveway should be scarified to a minimum depth of 6 inches, moisture-conditioned withitl 2 percent of optimum, and recompacted to at least 95 percent SFR Hoover Street * Limited Geotechnical Investigation* Carlsbad, CA * (858) 7.15-5800 * Project No. 00-080 * March 24, 2000 10 of 12 I 1· I I ... I I :1 I I ·I I I I I I I I I I of the Maximum Dry Density per ASTM D-1557. The aggregate base should also be compacted to a minimum of 95 percent relative compaction (ASTM 1557) and should be in conformance with the materials criteria as set forth in Section 26 of the Caltrans Standard Specifications, 1994 Edition. Concrete Pavements (PCC) Where rigid concrete pavements are planned to support light vehicular traffic, the following minimum sections are recommend~: Traffic Index 4.5 Recommended Pavement Section 6.0" PCC on Compacted Subgrade Comments Driveway Compaction of the subgrade soil should be conducted as specified for Asphalt Pavements, above. PCC Pavement should be minimum 3,500 psi concrete. It is recommended that steel reinforcement be provided for PCC pavements, which will sustain heavy impact loading, such as fire trucks. As a minimum for such slabs, we reGommend number 3 deformed rebar placed on 24-inch centers each way. Placement of concrete, control/expansion joints, and any reinforcement should be in conformance with ACI specifications and the Structural Engineer's design. ·Trench Backfill trench excavations for utility lines, which extend under structural areas should be properly backfilled and compacted. Utilities should be properly bedded and backfilled with clean sand or approved granular soil to a depth of at least 1-foot over the pipe. This backfill should be ul)ifonpJ.y watered and compacted to a firm condition for both vertical and lateral pipe supports. The remainder of the backfill may be typical on-site soil or low-expansive import which should be placed near optimum moisture content in lifts not exceeding 8 inches in thickness and mechanically compacted to a least 90 percent relative compaction. Surface Drainage Irrigation and drainage at this site should be designed to mamtain the current subsurface moisture regime. in a state of -relative natural equilibrium. Drainage -in hardscape areas adjacent to structures should · be designed· to collect and direct surface waters away from the proposed structures at a recommended minimum gradient of 1 percent. The drainage should be directed to approved drainage facilities. For earth areas, positive drainage with a minimum gradient of 5 percent away from all structures should be provided and maintained for a d.i~tance of at least 5 feet to reduce saturation of foundation soils. Earth swales should have a ~um gradient of 2 percent should be directed toward approved drainage receptors. Drainage patterns approved at the time of grading should be trutintained throughout the life of the development. Foundation Review SFR Hoover Street* Limited Geotechnical Investigation* Carlsbad, CA * (858) 715-5800 * Project No. 00-080 * March 24, 2000 · 11 of 12 · I I I . I I I I I I I I I I I I I I I I Foundation excavations should be reviewed by SAGE prior to the placement of forms, reinforcement, or concrete for ,conformance with the intentions of this investigation . . . CLOSURE. Limits of Investigation Our investigation was performed using the skill and degree of care ordinarily exercised, under similar circumstances, by reputable soils engineers and geologists practicing in this or similar localities. No other warranty, expressed or implied, is made as to the conclusions and professional advice included in this report. This report is prepared for the sole use of our client and may not be assigned to others without the written consent of the client and SAGE Engineering, Inc. The samples taken and used for testing, and the observations made, are believed representative of site conditions; however, soil and geologic conditions can vary significantly between test pits and surface exposures. As in most major projects, conditions revealed by construction excavations may vary with preliminary findings. If this occurs, the changed conditions must be evaluated by · a representative of SAGE and designs adjusted as required or alternate designs recommended. This report is issued with the. understanding that it is. the responsibility of the owner' or of his representative, to ensure that the information and recommendations contained herein are brought to the attention of the project architect and engineer. Appropriate recommendations should be incorporated into the structural plans. The necessary steps should be taken to see that the contractor and subcontractors carry out such recommendations in the field. The findings of this report are valid as of this present date. However, changes in the conditions of a property can occur with the passage of time, whether they are due to natural processes or the works of man on this or adjacent properties. In additi0n, changes in applicable or appropriate standards may occur from legislation or the broadening of knowledge. Accordingly, the findings of this report may be· invalidated wholly or partially by changes outside of our control. Therefore, this report is subject to review and should be updated after a period of three years. Additional Services The review of plans and specifications, field observations and testing under our direction is an integral part of the recommendations made in this report. If Testing Engineers-San Diego is not , retained for these services, the client agrees to assume our responsibility for any potential claims that may arise during construction. Observation and testing are additional services, which are provided by our firm, and should be budgeted within the cost of development. . ~ ~ . ******************** Testing Engineers-San Diego, Inc. SFR Hoover Street* Limited Geotechnical Investigation* Carlsbad, CA * (858) 715-5800 * Project No. 00-080 * March 24, 2000 · 12 of 12 I I I I I ,I I I I I I I I I I I I I I I I I I I I I I I I I- I I I I I I I I Testing Engineers-San Diego, Inc. . Project Name: SFR Hoover Street Geotechnical Investigation Carlsbad, CA rn ,.,,_mua ~'ORllf • /;t/ffff1 . A. N Scale: 1' = 1,000" ! ~..,.-' . · .. (: --~;f;r~l -~r'~" . . w......:.-_;.....;..,,_;_~~ .. ._. ~ -.} __ _ SITE LOCATION MAP -Figure 1 Project_No.: Date: 2000-080 March 2000 ·--· ---·. -----: --·-· --· --·· --Testing Engineers-San Diego, Inc. _ >(ST3: · "u~-/-~ . /I ..... -. .. d I f"llimn ; lf . • I \._ • I )b.ZZ v · :----i--.----r,io ~l?>b (!>~ ~ ,~z. re.o. 112; tfPli'.I . I=---. err ·t ::.,;;;,-u -t . ~ • f:U:,e,.. • • : ~. I , ~ •• 1" ~:--,c-=---..2~~~~~-::::t 1 ~ . 1 ( .. • ---'"'1,------;::;7.;': ',., \'Cl' I ---..('21 =7 Vj_y<. Explanation; IXI ST4 Test Pit Location (approx.) Project Name: SFR Hoover Street Geotechnical Investigation Carlsbad,. CA GEOTECHNICAL MAP -Figure 2 Project No.: Date: 2000-080 March 2000 I I I I I I I :I I I I I I I I I I I I 'I I I -1 I I I I I -I I I I I I I I I I " 1. 2. 3. 4. 5. 6. 7; 8. 9. REFERENCES Bonilla, M.G., 1970, Surface Faulting and Related Effects, in Wiegel, R. L., Earthquake Engineering, Prentice-Hall, Englewood Cliffs, p. 47-74. Bowles, J.E., 1977, Foundation Analysis and Design: New York, NY, McGraw-Hill, 750p. Hunt, R.E., 1986, Geofechnical Engineering Investigation Manual, New York, NY, McGraw-Hill, 983 p. Hunt, R.E., 1984, Geotechnical Engineering Techniques and Practices, New York, NY, McGraw-Hill, 729 p. · Jennings, C.W., 1994, Fault Activity Map of California and Adjacent Areas, California Division of Mines and Geology, Map No. 6, Scale 1:750,000. Kennedy, M.P. and Peterson, G.L., 1975, Geology of the San Diego Metropolitan Area, California, 1975, California Division of Mm.es and Geology, Bulletin 200. Uniform Building Code,, 1997 Edition: Whittier, CA; International Conference of Building Officials, 3 Volumes. Wesnousky, S.G., 1986, Earthquakes, Quaternary_ Faults, and Seismic Hazard m California, Journal of Geop];lysical Research, Vol. 91, No. B12, pp. 2587-2631. Winterkom, H.F., and Fang, H.Y., 1976, Foundation Engineering Handbook: New York, NY, Van Nostrand Reinhold, 751 p. · · I ·I I -1 I I I I I I I 1. I I I I I I I '' h, , ( ' " ' ' -','v ,, ' _,,. ~ , "' 1. I I I- I I I I I I I I I 1. I I I I I GENERAL NOTES SAMPLE IDENTIFICATION The Unified Soil Classification System is used to identify the soil unless otherwise noted. · SOIL PROPERTY SYMBOLS N: Standard "N" penetration: Blows per foot of a 140 pound hammer falling 30 inches on a 2-inch O.D. split-spoon. Qu: Unconfined compressive strength, tsf. Qp: Penetrometer value, unconfined compressive strength, tsf. Mc: Water content, %. LL: Liquid limit, % . Pl: Plasticity index, % • DD~ Natural dry density, PCF. v : Apparent groundwater level at time noted after completion. DRILLING AND SAMPLING SYMBOLS CAL: Modified California Sampler -2 5/8" I.D., 3.0" O.D., except where noted. SS: Split-Spoon-1 3/8" I.D., 2" O.D., except where noted. ST: Shelby Tube -3" 0 .D., except where noted. AU: Auger Sample. · DB: · Diamond Bit. CB: Carbide Bit. WS: Washed Sample. RELATIVE DENSITY AND CONSISTENCY CLASSIFICATION TERM (NON-COHESIVE SOILS) (SPT) Very Loose Loose Medium Dense Dense Very Dense TERM (COHESIVE SOILS) Very Soft Soft Medium Stiff Stiff Very Stiff Hard STANDARD PENETRATION RESISTANCE Oto4 4to 10 11 to 30 SPT Oto 2 2 to 4 4to 8 8 to 16 16 to 32 Over 32 · 31 to 50 Over 50 QU -(TSF) 0 -0.25 0.25 -0.50 0.50-1.00 1.00-2.00 2.00-4.00 4.00+ I I 1: I I I I I I I I I I ··1· I :1 I I I PARTICLE SIZE Boulders Cobbles Gi;avel 8 in.+ 8 in-3.in 3 in-5mm Coarse Sand 5mm-0.6mm Silt 0.074 mm-0.005mm Medium Sand 0.6mm-0.2mm Clay -0.005mm Fine Sand 0.2mm-0.074mm Testing Engi:ueers-San Diego, Inc. I I LOG OF TEST PIT I I I I -1 I I I -1- 1 I I PROJECT NAME: · DATE OBSERVED: LOGGED BY: DEPTI-1 (FEET) ·CLASS N SM - - - -5 - - - - 10 - - - - - 15 ------ . LOGGED-BY: MSD SM -- - -5 - - - 10 - -· ..,.. - - 15 - -I 00-0~0.tp I SFR Hoover Street 3/1/00 MSD GROUND ELEVATION: UNO BULK MOIST. SAMPLE SAMPLE CONT. DD /_\1:\ ·~ 15.1 X 9.5 117.7 GROUND ELEVATION: X 14.5 X 12.0 PROJECT NO: 2000-080 METHOD OF EXCAVATION: LOCA'rION: See Map "TEST PlT'NO.: · .IT:1., DESCRIPIION v• • • .. Topsail: Dai;k .brown silty sand, very moist, loose, fine grained, rootlets. @ 2.0' Formation: Terrace deposits consisting of brown to. dark brown sandstone, very dense, moist. Tenninated @ 7. 0' No Groundwater No Caving Backfilled on 3/1/00 -.. LOCATION: See Map TEST PIT NO.: T£::2 Topso1l: Dark brown silty.sand, very moist, loose, fine grained, rootlets. @ 1.0' Formation: Dark brown to reddich brown sandstone, llloist, medium dense to dense. . Tennibat~d@ 6.0' No Groundwater No Caving Backfilied om 3/1/00 ! -SOIL TEST I I I Testing Engineers-San Diego, Inc. PROJECT NAME: DATE OBSERVED: I I I I I I I I I I I I I I LOGGED BY: DEl'lH (FllET) CLASS .. SM - -. - - 5 - - - -10 ---- - 15 ---.. - LOGGED.BY: SM - - - -5 -GP - -. 10 - --. - - 15 - -I 00-080.tp I N MSD LOG OF TEST PIT SFR Hoover Street PROJECT NO: 2000-080 3/1/00 METHOD OF EXCAVATION: MSD GROUND ELEVATION: LOCATION: See Map TEST PIT NO.: .Tf:3_ . . . UNO BULK MOIST. ·SAMPLE SAl'vlPLE · CONT. DD .. J;)ESCRIPTION -. (II:\ . ' Topsoil: Dark brown silty sand, very moist, loose, fine &rained, rootlets. @ 1.0' Fonnatimr Reddish brown sandstone, moist, medium dense to dense, becomes drier below 2 -3 feet. Terminated@ 7.0' No Groundwater .No Caving Backfilled on 3/1/00 ... GROUND ELEVATION: LOCATION: See Map TEST PIT NO.: TE:.4 X SM Topsoj]: Dark brown silty sand, very moist, loose, fine 10.1 grained, rootlets. @ 1.0' Formation: Reddish brown sandstone, moist medium dense to dense, becomes drier below 2 -3 feet. 10.3 @ 6.0' conglomera~ layer about six inches thick. Tertninatecl@ 8.0' No Groundwater No Caving Backfilled om 3/1/00 I SOJLTEST .. ' . I I I .1~ ., I I I I I . I I I ·I I I I I I ' : ,' ',, ~~ -: '. ,_ ,', ': ' , ' ', ','. ,', ', --,. :, , ', e Y'-,A' _, I I I I I I I I I I I I ·1 I LABORATORY TESTING Laboratory Testing Program Laboratory tests were performed on representative soil samples· to determine their relative engineering properties. Tests were performed in accordance with test methods of the American Society for Testing Materials (ASTM) or other accepted standards. The following presents a brief description of the various test metb.ods used. Classification Soils were classified visually according to tbe Unified Soil Classification System (USCS). Visual classifications were supplemented by laboratory testing of selected samples in accordance with ASTM D-2487. The soil classifications are shown on the Exploration Logs, Appendix B. Maximum Dry Density/Optimum Moisture Content The laboratory maximum dry density and optimum moisture content of selected samples was determined in accordance with J\STM D-1_557, ~ethod A. The test results are provided in the following tables. · · Particle Size Analysis Particle size analyses were performed on selected representative samples in accordance with ASTM D-422. The results are provided in the following table. Expansion Index Expansion Index tests were performed on representative samples of the near-surface soils. Samples were remolded and surcharged to 144 pounds per square foot in accordance with the Uniform Building Code Standard No. 18-2. The test results are summarized in the following tabies. Direct Shear In order to determine the fill soil bearing capacity, a direct shear test was performed on a soil sample remolded to 90 percent relative compactjon in accordance to ASTM D 3080. The test results are provided in the following tables, I -I I I I I. I I I I: I I 1- I I I I, I I SUM1\1ARY OF LABORATQRY TEST RESULTS RESULTS OF MAXIMUM DENSITY TEST . (ASTM D-1557) . _ _ -. : :. s~ruple Loc~ti9n ·_ · ;;;,,~"'~" "'~"'"~',,,,'' ,:;.,,,,,,•w,, TP-1@ 2-4' TP-2@ 1-3' 133.0 pcf 132;0 pcf RESULTS OF PARTICLE SIZE ANALYSIS 3/8" #4 #10 #20 #40 #60 #100, #200 uses (ASTM D-422) 100 100 99 95 75 47 . 31 21 SM 8.5 % 9.5 % I- I I -1 I I I I I I I I :I I -1 I I I I RESULTS OF EXPANSION INDEX TESTS (UBC NO. 18-2) r.:===;;:;:::;:::::=============-===;;;;:;:::;:===.:::::;:.:;=,. ::;;.,=;:;;i;;"' ;:;=_ ·, •• , • • • .. , ,,, ~ UJCaiio11 .. ·· · · · •·. . . .. " ,:;: •.. r&g~~~;l IJ;......___._..,_-"-"--____.--'--'-""---'"----------.........,_--'---'--+---'------'=~""----"--"' TP-4@ 0-2' 0 (very low) I I I I I I I I I I ·1 I I I I I I I I 03/24/2000 TESTING ENGINEERS· SAN DIEGO TESDJOBNO: CLIENT: DIRECT SHEAR TEST DATA TESD LAB NO.: PROJECT: SAMPLE LOCATION: SOIL TYPE: . · W:lmeldala\Dlrecl Shearl(Dlrecl Shear 1·2-4.xls]DATA 3.50 3.00 2.50 1.00 0.50 y• 0,7494x+0,2488 R' • 0.9999 0,50 CALCULATED DATA 1.00 1,50 INITIAL, ·after 9onsollcfatlon/saturatlon · WET DENSITY . ORY DENSITY MOISTURE COMPRESSION(-) er EXPANSION (+) FINAL, at failure WET DENSITY DRY DENSITY MOISTURE COMPRESSION(•) or EXPANSION (+) NORMAL PRESSURE SHEAR STRENGTH FRICTION ANGLE= COHESION= 00-080 BRIDGE MOTOR INN 54028 SFR HOOVER STREET TP-2(!!!1'-3' . · · · · · · · · · SILTY SAND (RECOMPACTED :ro 90'!. MAXIMUM DRY DENSITY <a! OPTIMUM MOISTURE) DIRECT SHEAR G.RAPH 2.00 ~.50 NORMAL PRESSURE pcf 129,7 pcf 117.0 % 10.9% % .1.1% pcf 132.7 pcf 115,9 % 14.5% % 2.0% ksf 1.04 .ksf 1.04 ·3.00 3.50 4.00 4.50 131.8 126.9 118,6 115.4 11.2% 10.0% -1.4% 1.9% 134.8 132.1 117.4 114.9 14.9% 15.0% -0.3% 2.3% 2.06 4.06 1.78 3.30 36.9 de rees 0.25 ksf Plate I I I ·I .. I I I I I 1· ·1 I I I I I I I I GENERAL NOTES SAMPLE IDENTIFICATION The Unified Soil Classification System is used to identify the soil unless otherwise noted. SOIL ·PROPERTY SYMBOLS N: Standard "N" penetration: Blows.pei: foot or°a.140 pound haminer falling 30 inches ·on a 2-inch O.D. split-spoon. Qu: Unconfined compressive strength,. tsf. Qp, Penetrometer value, unconfined compressive strength, tsf. Mc: Water content, %. LL: Liquid limit, %. Pl: Plasticity index, % . DD: Natural dry density, PCF. V : Apparent groundwater level at time noted after completion. DRILLING AND SAMPLING SYMBOLS CAL: Modified California Sampler-2 5/8" I.D., 3.0" O.D., except where noted. SS: Split-Spoon -1 3/8" I.D., 211 O.D., except where noted. ST: Shelby Tube -311 O.D., except where noted. AU: Auger Sample. DB: Diamond Bit. . CB: · Carbide Bit. WS: WashedSample. RELATIVE DENSITY AND CONSISTENCY CLASSIFICATION TERM (NON-COHESiVE SOILS) Very Loose STANDARD PENETRATION RESISTANCE (SPT) 0 to 4 Loose Medium Dense Dense Very Dense TERM (COHESIVE-SOILS) · Very Soft Soft Medium Stiff Stiff Very Stiff Hard PARTICLE SIZE Boulders Cobbles Gravel 8 in.+ 8 in -3.in 3 in-Smm SPT o·to 2 2 to 4 4 to 8 8 to 16 16 to 32 Qy~r 32 4 to 10 11 to 30 31 to 50 Over 50 Coarse Sand 5mm-0.6mm Medium Sand 0.6mm.,0.2mm Fine Sand 0.2mm-0.074mm OU -(TSF) 0 -0.25 0.25 -0.50 0.50-1.00 1.00-2.00 2.00 -4.00 4.00+ Silt 0.074 mm-0.005mm Clay 0.005mm