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Home My WebLink AboutTract Map 3929 Lot 257 Subsurface Soils & Geologic Investigation , ~ j . \'\~ 3C\'Z..C\ I...dt" 2S1 . June 06, 2002 W.O. 00576 Mrs. Kim Grobler 30290 Church Hill Ct. Temecula, CA 92591 wac GBDTBCHNlCaL -INC. Subject: Subsurfuce Soils Engineering and Engineering Geologic Investigation for Proposed Residential GradinglResidential Building Construction and Foundation Evaluation for Property Known as Lot 257, Tract 3929, City of Temecula, County of Riverside, California A.P.N.921-232-003 Gentlemen: Presented herein, per your request, are the results of our subsurface soils engineering and engineering geology investigation for proposed residential development for Lot 257, Tract 3929, City of Temecula, County of Riverside, California (see Figure 1, site vicinity map). The results of our investigation indicate that the soils underlying the proposed building and grading areas are comprised of Pleistocene nonmarine silty fine to very coarse-grained sandstone in a loose to medium dense to dense state. The property has previously been graded producing a building pad bounded by 2: 1 cut slopes to heights ranging from approximately 7 feet to 23 feet. Based upon information supplied to this office it is proposed to construct a residential building on the subject property. At the time of this investigation, no Grading Plan was available for review, an assessor's Plat Map was utilized as a base map for field review and plotting of exploratory borings (Plate I). It is proposed to construct conventional spread footings for slab-on-grade residential building. It is our opinion that the site should be considered suitable for the planned development, provided the recommendations presented herein are incorporated into design and in construction. Adequately constructed spread footings founded into competent, field approved dense bedrock materials are expected to provide necessary support for the planned residential structure. This report has been prepared in accordance with the generally accepted engineering standards ; considercd necessary for the proposed development. Thank you for the opportunity to be of service on your project. Should you have any questions . regarding this ~~~,4a, ~,ca..Il the undersigned at your convenienche ROf E, ,~" IRespectfuIl~Bm\~oor~,~u;.", fl / &,~ \' :)St01'.'" (<I:'{f ~:;;~ \ . ~ ~'I\.N ~ 7'('\ W~C ~teO~'ca~I,In,~' ;..i),i- & ~s ~ '%\ \ I'" I'I. ,....., :!(" os ~ \ f' Ii I' Stan Schupp 0:: ..., c :z ~ \, \"'~ i' "'b ,.,., I L. Wade W~f~~i~;r~!" ' RCE 14568, Exp. 3/3 II 4.568 .." ~ I CEG 1308. i'...~l;F/!H/03oV::r" 00576/95A.1>. ~ ; DXP, ~ Of (~"",. _~ CIVIL ~ ' ~ ~"" OF CAl\t()~ / ' --"' P.O. DOl 3&4 . 39333 North Share Dr. . FIWDSkID, 1:1 83333 18771 m-m7 . IDDSI 878-3337 . FII19D91 878.3347 \ I!) , ,.... o ~ ~ ..... ;;r () ~ '" ~ !'? ;;? ~ Po (i) :>. Q; <0 01 <0 l> -l>. . .j>. @1997 Thomas Bros. M '" .~)~..o.~ . -;. '0 "'\ "C". .,.. , \,("""1 ..,.. .'2 ,-"' \0 \2 CD CD <" \ "GJ ~ ~ 1z ~ '- , \ ~ .., g I:J;: ."G ~- '?:J ',"" i '~ IT> 'n.... ',," /!::'- i~'-.) /~ )> )> I I , , / ~'" .~,. ,~'i' f , I I OJ GGll. .... - C> 15 a o 8 "" '" Site Vicinity Map Figure 1 2. . . W.O. 00576 Tract 3932, Lot 257 1.0 Introduction This report presents the results of our subsurface soils engineering and engineering geology investigation for proposed residential development for Lot 257, Tract 3929, City of Temecula, County of Riverside, California (see Figure 1, site vicinity map). The purpose of this evaluation is to determine the nature and engineering properties of the subsurface soils, engineering geologic site evaluation and to provide necessary geotechnical recommendations for foundation design, site grading, utility trench backfiIl, and field review during construction. OUT evaluation included field review, subsurface exploration, soil sampling, laboratory testing, engineering analyses, review of referenced published information and preparation of this report. The recommendations contained herein reflect our professional opinions for the subsurface soil conditions encountered during our field investigation. 1.1 Proposed Development Based upon information supplied to this office it is proposed to construct a residential building with attached garage on the subject property. The property is to be served by a seepage pit system. The property has been previously graded producing a building pad bounded by approximate 2: I cut slopes to heights up to approximately 23 feet (east side), approximately 15 feet south side, and approximately 10 feet north side. Ingress and egress from the property is via a graded driveway (unpaved) off Via Monterey. At the time of this investigation, no Grading Plan was available for review, an assessor's Plat Map was utilized as a base map for field review and plotting of exploratory borings (Plate 1). Conventional spread footings are proposed for the building pad areas. Developed lot is to be served by seepage pit system. It is our opinion that the site should be considered suitable for the planned development, provided the recommendations presented herein are incorporated into design and in construction. Adequately constructed spread footings founded into competent, field approved bedrock materials are expected to provide necessary support for the planned residential structure. 1.2 Site Description The subject property is located southwest of the intersection of Avenida Barca and Via Monterey, Temecula, County of Riverside, California. Access to the property is off Via Monterey via an unpaved driveway. The property has been previously graded, a few years back, producing a building pad which has not been built upon. The property is mantled by native grass and weed growth. Approximate 2: I cut slopes bound the subject property to heights up to approximately 23 feet (east side), approximately 15 feet (south side) and approximately 10 feet north side, and approximately 4 feet west side. The subject property is bounded by residential property to the west. Via Monterey to the north (and residential property, north side of Via Monterey), Avenida PAGE 3 WAC Geotechnical, Inc. -3 . . W.O. 00576 'rract 3932, Lol2S7 Barca to the east (with residential property on the east side of Avenida Barca and residential property to the south. The property drains by sheet flow to the north and exhibits shallow ponding in the central southern region. 2.0 Scope of Work Geotechnical investigation for the subject site included subsurface exploration utilizing a truck mounted B-34, 8-inch auger-drill rig, soil sampling, laboratory testing, engineering analyses and preparation of this report. In general, scope of work included the following tasks: o Four exploratory auger borings were excavated, advanced to a maximum depth of 35.0 feet below the existing grade (see Plate I & Boring Logs, Appendix Section). During exploration, encountered subsurface soils were logged based upon visual and tactile methods with bulk samples obtained at subsurface zones at or near programmed pad grade. Collected samples were transferred to our laboratory for testing and analyses. Descriptions of encountered subsurface soils are provided on the Boring Logs in Appendix Section. Approximate locations of test borings are shown on Plate I. o Laboratory testing conducted on select bulk and remolded samples were programmed according to the project requirements. The laboratory testing included determinations ofIn-place Dry Density and Moisture Content, Maximum Dry Density and Optimum Moisture content, soil Shear Strength, Consolidation characteristics (based upon remolded samples) under anticipated structural loadings and expansive index. Descriptions of the test procedures used and test results are provided in Appendix Section. o Based upon obtained data resulting from our field investigation, laboratory testing and engineering analyses, this report presents this firms recommendations for foundation design, site preparation, grading and inspections necessary during site construction. 3.0 Subsurface Conditions Our evaluation of the site subsoil conditions are based upon subsurface soil exploration and noted laboratory testing. For the depths explored, proposed pad areas, contains loose porous weathered bedrock soils to an . approximate depth of 18-24-inches consisting of silty very fine to coarse-grained sand. Underlying bedrock soils are comprised of dense, silty fine to coarse-grained sandstone and clayey fine-grained sandstone/sandy claystone. Based upon our field investigation, soil sampling and subsequent laboratory and engineering analyses, the following characteristics for the site soils are observed: PAGE 4 WAC Geotechnical, Inc. 4. . . w.o. 00576 Tract 3932. Lot 257 In general, the upper 0 to 12:t inches of the site soils comprising the structural pad areas are loose and compressible. These soils, will require penetration by structural footings to a depth of 24-inches into competent bearing subgrade (bedrock). Areas for concrete slab on grade will require ripping to a depth of 12-inches, moisture conditioning to at nor near optimum moisture content followed by compaction to 90% relative to the laboratory maximum dry density for the subject site soils. In-place and approved competent dense bedrock materials should be considered to be suitable for structural foundation support for planned residential construction. Laboratory shear tests conducted on the upper bulk samples remolded to 90 percent ofthe laboratory determined Maximum Dry Density indicate moderate shear strengths under increased moisture conditions. Results of the laboratory shear tests are provided in Plate A-I in Appendix Section. Consolidation tests conducted on remolded samples at depths of 0-5 feet, indicate low potential tor compressibility under anticipated structural loadings. Results of the laboratory determined soils consolidation potential are shown on Plate B-1, Appendix Section. Site soils are classified as silty fine to coarse-grained sand. Site soils are considered to have very low expansive potential with an expansive index ofE.I. of 12. 3.2 Excavatibility Considering the state of the non-lithified sandstone/siltstone bedrock materials below current surface grade, it is our opinion that grading and excavation required for the project may be accomplished using conventional construction equipment to proposed design grades and recommended removal depths. Our subsurface drilling program drilled to depths up to 35 feet. 3.3 Groundwater Encountered subsoils at depths of35.0 feet were in a moist state. Groundwater was not encountered during our subsurface drilling excavation to depths up to 35.0 feet. Proposed construction area is on a hilltop area underlain by dense sandstone/siltstone bedrock materials. Ground water is not expected to be a problem during site construction to anticipated removal depths. 3.4 Subsurface Variations Based upon the results of our subsurfuce investigation and on past experience, it is the opinion of this firm that variations in the continuity, depths of subsoil deposits may be expected. Due to the nature and characteristics of the soils underlying the subject site, care should be exercised in interpolating or extrapolating the conditions and properties of the subsoils beyond the boring locations. PAGE 5 WAC Geotechnical, Inc. s . . W.O. 00576 Tract 3932. Lot 257 3.5 Geology The subject property is located within a Pleistocene nonmarine bedrock materials. Deposits on-site are classified as bedrock comprised of silty very fine to coarse-grained sandstone, siltstone and sandy claystone/clayey sandstone. The approximate 2: I cut slopes around the graded pads expose massive sandstone/siltstone and are considered to be grossly stable. Existing slopes are not affected by landsliding. Large natural bodies of water do not exist on the subject property or adjacent to the subject property. Therefore, the subject property is not threatened by seismic induced tsunami or seiching phenomenon. Design engineer should review subject property for proper drainage away from proposed foundation construction to approved areas. Drainage should not be allowed to drain over slope faces from pad areas 3.6 Alquist/Priolo Special Studies Zones The subject property is not located in a state mandated Special Studies Zone for Active limiting. 3.7 Potential Seismic Hazards Seismic Design Parameters Based upon 1997 UBC The seismic design fault for the subject property is the Elsinore Fault, Glen Ivy segment which is located within 5.7 kilometers to the subject property. The fault type is "B." The maximum magnitude is noted by the UBC as 6.8. The slip rate is 5 mm/yr. The Near-Source Factor N" is noted as 1.12; the Near-Source Factor Nv is noted as 1.36. The sandstone/siltstone bedrock underlying the subject site, is assigned the Soil Type Profile SD, The Seismic Zone Factor is 0040. The Seismic Coefficient, C" is noted as 0044N,,, the Seismic Coefficient, Cv, is noted as O.64Nv. 3.8 Liquefaction Liquefaction is caused by the build up of excess hydrostatic pressure in saturated cohesionless soils due to cyclic stress generated by ground shaking during an earthquake. The significant factors on which liquefaction potential of a soil deposit depends, among others include, soil type, , relative soil density, intensity of earthquake, duration of ground shaking, and depth of ground water. Ground water was not encountered in our subsurface exploration program and is not considered to be within 35 feet of the surface grade. Underlying in-place bedrock materials consist of dense sandstone and siltstone and sandy claystone/clayey sandstone. Based upon available information PAGE 6 WAC Geotechnical, Inc. , . . W.O. 00576 Tract 3932, Lot 257 from this investigation, it is the opinion of this firm that the potential for liquefaction is minimal for the subject property. 4.0 Evaluations and Recommendations 4.1 General Evaluations Based on this firm's field investigation, laboratory testing and subsequent engineering analysis, it is our opinion that, from a geotechnical viewpoint, the site should be considered suitable for the planned development, provided the recommendations presented herein, are incorporated into final design and in construction. Site preparation and grading should be performed in accordance with the enclosed grading section recommendations of this report, except as modified in the main text and with the applicable portions of Appendix Chapter 33 of the current UBC or applicable local ordinance. Structural design considerations should include the probability of moderate to high peak ground accelerations from relatively active nearby earthquake faults as noted in Section 3.7. 4.1.1 SubGrade Preparations for Structural Fill Area The upper 12-inches of the subject property, area of proposed construction, should be ripped to a depth of 12-inches, moisture conditioned to at or near optimum moisture content and compacted to 90% relative compaction as compared to the controlling maximum dry density for the subject site soils and verified by testing (ASTM D1557-91 and D 2922-96). Footings for subject residential construction will require embeddment into bedrock materials, a minimum of24-inches below adjacent grade. Exposed earth materials shall be a minimum of90% relative dry density as compared to the prevailing maximum dry density for the site Fill should be placed under the observation and testing of the project soils engineering consultant. In-place and approved competent dense bedrock materials should be considered to be suitable for structural foundation support for planned residential construction. At time of construction, actual field exposures will dictate site suitability based upon field review by the project engineering geologist or soils engineering consultant. General earthwork recommendations are enclosed with this report. Recommendations for field placement offill is to take the form of thin layers of soil (not to exceed 6 inches) moisture conditioned and compacted by sheepsfoot roller (or other approved compaction equipment) with 90% relative compaction as compared to the Maximum Density/Optimum Moisture value of the soil. Fill should be placed under the observation and testing of the project soils engineering consultant and as noted below in grading section. PAGE 7 WAC Geotechnical, Inc. 1 Tract 3932. Lot 257 GRADING I. 4. 5. 6. PAGE 8 . . w.o. 00576 After approval of overexcavation and prior to placement of any compacted fill, the materials, the exposed stripped ground surface and bottoms of all excavated areas which are to receive fill should be scarified to a minimum depth of 6 inches, moisture conditioned to slightly above optimum moisture content and then rolled and compacted to 90 percent of the laboratory. maximum density as determined in accordance with ASTM: Test Method D-1557-91. Unless otherwise specified, all references to compaction within this report relate to that standard. 2. Approved on-site earth materials or imported soils should then be spread in thin lifts, watered to slightly above optimum moisture content and then rolled and compacted to a minimum of90 percent of the applicable laboratory maximum density. Each lift should be treated in a like manner until the desired grade is achieved. 3. Import soils, if required, should consist of clean, non-expansive compactible materials similar to on-site soils and should be free of trash, debris or other objectionable materials. Plans and specifications should indicate that the grading contractor shall notifY the project soils engineer not less than 72 hours in advance of the location of any soils proposed for import. Each proposed import source shall be sampled, tested and approved prior to delivery of soils for use on the site. All of the above overexcavation and earthwork should be performed under the observation and testing of the project soils engineering consultant and engineering geologist. All fill should be tested at the time of placement to ascertain that the required compaction is achieved. The minimum basis of testing should be one (I) test per two (2) feet of fill depth or per each 500 cubic yards of fill placed. Subdrains will be required in the natural swale areas below engineered fills. The lower portions of the subdrains may require outletting through compacted fill via solid pipe. A concrete headwall will be required at the fiIl!bedrock contact. Backdrainage devices with lateral outlets will be required for stabilization fiBs over 10 feet in vertical height or as field conditions dictate. The installation of the backdrainage systems should be observed by the soils engineer and/or engineering geologist. WAC Geotechnical, Inc. ~ Tract 3932. Lot 257 7. 8. 9. 10. II. PAGE 9 . . W.O. 00576 The cut portion of the building pads traversed by cut/fill daylight lines should be overexcavated to a minimum depth of three feet and replaced to design grade with a compacted blanket fill to reduce potential differential settlement effects. Building pads above stabilization fiIls must also be overexcavated a minimum of three feet and capped with a compacted fill blanket to inhibit surface moisture infiltration. Cut pads which may expose fault or shear zones at finish grade should be overexcavated to a minimum depth of four feet and replaced to grade as directed by the soils engineer and/or engineering geologist. FilI-over-cuts are acceptable provided the fill portions are constructed on a keyway founded in firm bedrock. The width of the keyway should be excavated to one-haJfthe slope height or a minimum of 15 feet, which ever is greater. The keyway should slope from toe to heel with a minimum differential of one foot. Where uncertainty relative to the suitability of the cut is present. the cut portion should be exposed prior to fill placement. Final determination should be made bv the proiect engineering geologist. Where the natural or existing graded slope is steeper than 5 feet horizontal to foot vertical and where designated by the soils engineer or engineering geologist, compacted fill material should be keyed and benched into bedrock or firm material during grading. Care should be taken to avoid benching above the proposed finished pad surface. In order to minimize surficial slumping on compacted fill slopes, the following grading procedures should be undertaken: a. Compacted fill slopes should be backrolled during placement at intervals not exceeding 4 feet in vertical height. Care should be taken to construct the slopes in a workmanlike manner so that they are positioned at the design orientation and slope ratio. Achieving a uniform slope surface by subsequent thin wedge fiIling must be avoided. Any add-on correction to a fill slope should be conducted by overfilling the affected area in horizontal, compacted lifts which must be benched into the existing fill prism. The overfill slope may then be trimmed to the design gradient. After completion, the fill slope faces shall be rolled for the entire height with a sheepsfoot roller and the finished with a grid roller. Ifthe desired compaction is not obtained in this manner, a vihratory sheepsfoot roller WAC Geotecbnical, Inc. q Tract 3932, Lot 257 13. PAGE 10 . . W.O. 00576 may be required. To be most effective, this equipment should be anchored and manipulated from a side-boom tractor. In lieu of a grid roller, the slope may be track rolled with a D-S dozer or equivalent machinery on slopes of2: 1 or flatter. To obtain the required compaction and appearance ofthe slope face, the soil moisture should be maintained at or near optimum from the time of mass filling to the completion of grid rolling. b. As an alternative to Item a., fill slopes may be constructed by overfilling a minimum 00 feet, compacting and then trimming back such as to expose the dense inner core of the slope face. c. The grading contractor should be aware that care must be taken to avoid sloughing ofloose material down the face of the slopes during construction. Fine grading operations should not deposit loose, trimmed soils on any of the finished slope surfaces. These materials should be removed from slope areas. 12. Although oversized rock material was not encountered during our investigation, should oversize boulders be generated during grading, all rock burial must be in accordance with the Grading Code and recommendations from this firm, or be wasted oflSite. AIl haul roads, ramp fills, and tailing areas should be removed during and as part of the mass grading operations. 14. Normal earthwork grading schedules are established by the project grading contractor, initially in the bidding and subsequent pre-job planning stages of the project. Delineating and maintaining absolute controls over specific backcut exposure time imposes difficulties in enforcement, particularly when considering the wide variation in size of engineered earthwork stabilization and the range in capabilities of grading contractors participating in the bidding process. In lieu of assigning a specific time limit, this firm would recommend incorporating the following as a note on the grading plan. "It is imperative that the grading schedule be coordinated by the project grading contractor to minimize the unsupported exposure time of temporary backcuts created during landslide or buttress and stabilization fill construction as well as other unsuitable soils removal. Once started, temporary excavations and subsequent fill operations should be maintained to completion without intervening delays imposed by avoidable circumstances. Grading should be planned to avoid WAC Geotechnical, Inc. 1.0 . . W.O. 00576 Trnct 3932. Lot 257 exposure at or near-grade temporary backcut excavation through non-work periods. Where improvements (either on or offiite) may be affected by temporary instability, further restrictions such as slot cutting, extending work day and/or weekend schedules, or other requirements considered critical to serving the specific circumstances may be imposed. " 4.2 Spread Foundations For adequate support, the proposed structures may be constructed on continuous and/or isolated spread footings founded exclusively into field approved bedrock materials. Conventional shallow foundation system is considered suitable for planned residential and ancillary structures. Sulfate content is 320 parts per million and is considered moderate. Type II, l'P(MS), IS (MS) cement is recommended. Foundations may be designed based upon the following values: start here Allowable Bearing: Lateral Bearing: Sliding Coefficient: 1500 Ibs./sq.ft. 255 lbs./sq.ft. per foot of depth to a maximum of1500 lbs./sq.ft. 0.28 The above values may be increased as allowed by Code to resist transient loads such as wind or seismic. Building'code and structural design considerations may govern depth and reinforcement requirements and should be evaluated. 2. Other Design Recommendations * FOOTING DEPTH Exterior 24-inches below lowest adjacent grade in approved bedrock materials for one story and 30-inches below adjacent grade in approved bedrock materials for 2-story. Interior 24-inches below lowest adjacent grade in approved bedrock materials for one story and 30-inches below adjacent grade in approved bedrock materials for 2-story. * FOOTING WIDTH Exterior 12-15 inches minimum for one and 2-story, respectively. Interior 12-15 inches minimum for one and 2-story, respectively. PAGE 11 WAC Geotechnical, Inc. \l . . W.O. 00576 Tmct 3932, Lot 257 * FOOTING REINFORCEMENT Exterior & Interior All continuous; four No.4 bars, two near the top, two near the bottom for exterior and two No.4 bars, one near the top and one near the bottom for the interior. Concrete Slabs Slab Thickness: 4-inches net, reinforced with 6x6-6/6 WWF, or with #3 rebar at 16-inch o/c, is recommended. Reinforcement should be installed at mid-height in the slab. * Under-Slab Treatment Living Areas 10-mil Visqueen; cover with at least 2 inches of sand. Subgrade soils should be presoaked to contain at least optimum moisture content immediately prior to placing Visqueen and to be verified by the soils engineering consultant. The sand cover should be moistened prior to placing concrete. Grade Beam A grade beam reinforced continuously with the garage footings should be constructed across all garage entrances, tying together the ends of the garage footings. This grade beam should be embedded at the same depth as the adjacent perimeter footings Garage Slab Optimum moisture content in subgrade soil verified by the soils engineering consultant. * FireD lace Footings - Fireplace footings shall have a minimum embeddment depth of24-inches measured from the lowest adjacent grade and should be an integral part of the building foundation system. Fireplace slabs shall be treated in the same manner as the living area slabs. *Prior to pouring footings, soils should be pre-moistened and field approved by the project soils , engineering consultant or his representative. The settlement of properly designed and constructed foundations supported on approved earth I materials, carrying maximum anticipated vertical loadings, are expected to be within tolerable I limits. Estimated total and differential settlements should be no more than 3/4 and I12-inch, I respectively for 40 lineal feet. .PAGE 12 WAC Geotechnical, Inc. \2. . . W.O. 00576 Tract 3932. lot 257 4.3 Resistance to Lateral Loads Resistance to lateral loads can be restrained by friction acting at the base offoundations and by passive earth pressure. A coefficient of friction of 0.28 may be assumed with the normal dead load forces for footing established on bedrock materials. An allowable passive lateral earth resistance of255 pounds per square foot per foot of depth, may be assumed for the sides offoundations poured against bedrock materials. However, the maximum lateral passive earth pressure is recommended not to exceed 1500 pounds. For design, lateral earth pressures ofIocal soils when used as level backfiIl may be estimated from the following equivalent fluid density: Active: Passive: At Rest: 42 pcf 255 pcf 64 pcf 4.4 Construction Considerations 4.4.1 Unsupported Excavation Temporary construction excavations up to a maximum depth of 5 feet may be made without any lateral support. It is recommended that no surcharge loads such as construction equipment, be allowed within a line drawn upward at 45 degree from the toe of excavation. Use of sloping for deep excavations may be applicable where plan dimensions ofthe excavation are not constrained by any existing structure. 4.4.2 Supported Excavations If vertical excavations exceeding 5 feet in depth become warranted, excavation should use shoring to support side waIls. 4.5 Site Preparation Site preparations may include cut subexcavations and placement of soils as engineered fill. Such earth work should be in accordance with the applicable grading recommendations provided in the current UBC and as recommended within this report. This office should be notified 72 hours in advance of importing soils to site for placement as compacted fill. It will be necessary for the project soils engineering consultant to sample import , soils with subsequent laboratory testing to determine suitability of import soils for project construction. It is strongly recommended that import soils be similar to site soils. The use of clayey soils for pad construction is not recommended. PAGE I3 WAC Geotechnical, Inc. \3 . . w.o. 00576 Tract 3932. Lot 257 4.6 Soil Caving During excavations for deep utility trenches, 'some' caving may be expected. All temporary excavations should be made at a 2: I (horizontal to vertical) slope ratio or flatter, and/or as per the construction guidelines provided by CaIOSHA. 4.7 Retaining Wall Retaining structures, if planned, should be designed using the following equivalent fluid density: Slope Surface of Equivalent Fluid Density (pct) Retained Material Imported Local (horz. to vert.) Clean Sand Site Soil Level 30 42 2:1 35 64 Only free-draining granular materials (sand or gravel) as retaining wall backfill. Backdrains will be required behind all retaining waIls. 4.8 Utility Trench Backfill Utility trench backfill within the structural pad and beyond, should be placed in accordance with the following recommendations: o Exterior trenches along a foundation or a toe of a slope and extending below a 1: I imaginary line projected from the outside bottom edge of the footing or toe of the slope, should be compacted to a minimum 90 percent. o All excavated trenches should conform to the requirements and safety as specified by the CalOSHA 4.9 Pre-Construction Meeting It is recommended that no clearing of the site or any grading operation be performed without the presence ofa representative of this office. An on-site pregrading meeting should be arranged . between the soils engineering consultant and the grading contractor prior to any construction. 4.10 Seasonal Limitations No structural fill shall be placed, spread or rolled during urtfavorable weather conditions. Where the work is interrupted by heavy rains, fill operations shall not be resumed until moisture conditions are considered favorable by the soils engineering consultant. PAGEJ4 WAC Geotechnical, Inc. \4. . . W.O. 00576 Tract 3932, Lot 257 4.11 Planters To minimize potential differential settlement to foundations due to subsurfuce migrating water from watering, planters requiring irrigation should be restricted from use adjacent to footings. If unavoidable, planter boxes with sealed bottoms and drain outlets to approved areas away from the foundation, should be constructed. 4.12 Landscape Maintenance/Drainage Only the amount of irrigation necessary to sustain plant life should be provided. Pad drainage should be directed towards streets and to other approved areas away from foundations. Slope areas, when applicable, should be planted with draught resistant vegetation. Drainage should not be allowed to flow over slope faces from pad areas. 4.13 Observations and Testing During Construction Recommendations provided in this report are based upon the assumption that all foundations will be placed upon field approved bedrock materials for structure. Excavated footings should be field reviewed, verified and certified by soils engineering consultant and/or engineering geologist prior to forming, steel and concrete placement to ensure their sufficient embeddment and proper bearing on approved dense bedrock materials. Additional field reviews by soils engineering consultant and/or engineering geologist are recommended to verifY footing excavations being free ofloose and disturbed material. All structural backfill should be placed and compacted under direct observations and testing by this facility. Excess soils generated from footing excavations should be removed from pad areas and such should not be allowed on subgrades as uncompacted fill for areas programmed to receive concrete slab-on-grade. 4.14 Plan Review The recommendations presented herein should be considered 'preliminary.' It is recommended that "precise grading plans" or foundation plans should incorporate the recommendations contained herein. Further, excavated footings should be verified as recommended earlier. If during construction, conditions are observed to be different from those as described in this report, revised and/or updated recommendations will be required. PAGE 15 WAC Geotechnical, Inc. \:5" . . W.O. 00576 Tract 3932, Lot 257 5.0 Closure The conclusions and recommendations contained herein, are based on the findings and observations made at the time of the subsurface investigation. The recommendations presented, should be considered "preliminary" since they are based on soil samples only. If during construction, the subsoil conditions appear to be different from those disclosed during field investigation, this office should be notified to consider any possible need for modification for the geotechnical recommendations provided in this report. Recommendations provided are based on the assumptions that structural footings will be established exclusively into field approved bedrock materials. It is recommended that final "precise grading and foundation plans" should contain recommendations made herein within context of report. Site grading, ifperformed, must be performed under review by geotechnical representatives of this office. All footing excavations should be field reviewed prior to forming, steel and concrete placement to ensure that foundations are founded into satisfactory soils and excavations are free ofloose and disturbed materials. A pregrading meeting between grading contractor and soils engineering consultant should be . arranged, preferably at the site, to discuss the grading procedures to be implemented and other requirements described in this report to be fulfilled. This report has been prepared exclusively for the use of the addressee for the project referenced in context. It shall not be transferred or be used by other parties without written consent by WAC Geotechnical, Inc. We cannot be responsible for use of this report by others without ,review of the grading operation by our personnel. : Should the project be delayed beyond one year after the date of this report, the I recommendations presented shall be reviewed to consider any possible change in site conditions. J;he recommendations presented are based on the assumption that the necessary geotechnical I observations and testing during construction will be performed by a representative of this office. J;he field observations are considered a continuation of the geotechnical investigation performed. i If another firm is retained for geotechnical observations and testing, our professional liability and I responsibility shall be limited to the extent that WAC Geotechnical, Inc. would not be the I geotechnical engineering consultant of record. IPAGE 16 WAC Geotechnical, Inc. ~ Tract 3932, Lot 257 . 1. Field Exploration 2. Boring Logs 3. Laboratory Test Programs 4. Professional Limitations 5. References 6. Plate I PAGE 17 APPENDIX Section WAC Geotechnical, Inc. . W.o. 00576 \l . . W.O. 00576 Tract 3932, Lot 257 Field Exploration The field investigation for the project included site reconnaissance and subsurfuce exploration using a truck mounted B-34 auger dril1 rig for subsurfuce investigation. During the site reconnaissance, the surfuce conditions were noted and test boring locations were determined. Soils encountered during exploration were continuously logged and classified by visual observations and tactile methods in accordance with generally accepted field classification. The field descriptions were modified, where appropriate, to reflect laboratory test results. Where appropriate, representative bulk soil samples were obtained. Logs ofthe exploratory borings are presented in the following summary sheets, that include the description of the subsoil materials encountered. PAGElS WAC Geotechnical, Inc. ~~ Tract 3932, Lot 257 . IPAGE 19 Boring Logs WAC Geotechnical, Inc, . W.o. 00576 \t:t . . Borine Loes B-34 Auger Drill Rig 8-1. Elevation: Elevation as of5/31!02 Depth in Feet Description 0.0-1.0' Bedrock: Silty fine to medium-grained sandstone, It tan brn, dry, loose; porous Soil Classification: SM Sample 1.0-5.0' Silty fine-grained sandstone, tan brn, moist, medium dense to dense; drive tube sample at 2.5 ft. 115.6 @ 7.4% Soil Classification: SM 5.0-7.0' Silty very fine to fine-grained sandstone, tan brn, moist, dense; Soil Classification: 8M End of boring @ 7.0', no water, no caving B-2. Elevation: Elevation as of5/3I102 Depth in Feet Description 0.0-1.2' Bedrock: Silty fine to coarse-grained sand, brn, dry, loose, porous; Soil Classification: SM Sample Bulk @ 0.0-5.0' 1.2-6.0' Very fine to very coarse-grained sandstone, brn, dense Soil Classification: SW 6.0-12.0' Silty very fine-grained sandstone, It tan brn, moist, dense; Soil Classification: SM 12.0-17.0' Fine to very coarse-grained sandstone, It brn, moist, dense, Soil Classification: SW 17.0-19.0' Fine to very coarse-grained sandstone, bm very moist, dense Soil Classification: SW 19.0-33.0 Clayey fine-grained sandstone, grayish brn/dk brn, moist, dense Soil Classification: SC 33.0-34.0' Slightly clayey fine to coarse-grained sandstone, dk bm, moist dense; Soil Classification: SC/SW ,34.0-35.0' Silty very coarse-grained sandstone, It brn, moist, dense Soil Classification: SM/SW End of boring @ 35.0', no water, no caving WAC Geotechnical, Inc. zo . . Borine Loes B-34 Auger Drill Rig B-3. Elevation: Elevation as of 5/31/02 Deoth in Feet Descriotion 0.0-1.3' Bedrock: Silty very fine-grained sandstone,tan, dry, loose; porous Soil Classification: SM Sample 1.3-2.0' Silty fine-grained sandstone, tan brn, moist, medium dense to dense; drive tube sample at 2.5 ft. 116.2 @ 7.3% Soil Classification: SM 2.0-5.0' Silty very fine to fine-grained sandstone, tan brn, moist, dense; Soil Classification: SM End of boring @ 5.0', no water, no caving 8-4. Elevation: Elevation as of5/31/02 Depth in Feet Description 0.0-1.5' Bedrock: Silty fine-grained sand, It tan brn, dry, to slightly moist, loose to medium dense, porous; Soil Classification: SM Sample 1.5-2.0' Very fine to medium-grained sandstone, h brn, medium dense to dense; Soil Classification: SW , 2.0-6.0' Fine to coarse-grained sandstone, It brn, moist, dense; Soil Classification: SW 16.0-7.0' Very fine to medium-grained sandstone, h brn, moist, dense, Soil Classification: SW , 7.0-II.Of Silty very fine-grained sandstone, It tan brn, moist, dense Soil Classification: SM 11.0-22.0' Fine to very coarse-grained sand, It brn, moist, dense Soil Classification: SW ,22.0-25.0' Silty fine to coarse-grained sand, It brn, moist to very moist, Soil Classification: SM/SW :25.0-34.0' Clayey very fine to fine-grained sandstone, dk brn, moist, dense Soil Classification: SM/SW '34.0-35.0' Silty very coarse-grained sandstone, It brn, moist, dense Soil Classification: SM/SW End of boring @ 35.0', no water, no caving WAC Geotechnical, Inc. 2-\ . . W.O. 00576 T~t3932.Lot2S7 Laboratory Test Programs Laboratory tests were conducted on representative soils for the purpose of classification and for the determination ofthe physical properties and engineering characteristics. The number and selection ofthe types oftesting for a given study are based on the geotechnical conditions ofthe site. A summary of the various laboratory tests performed for the project is presented below. Direct Shear (ASTM 0 3080) Data obtained from this test performed at increased moisture conditions on remolded soil samples were used to evaluate soil shear strengths. Samples contained in brass sampler rings, placed directly on test apparatus are sheared at a constant strain rate under a normal load, appropriate to represent anticipated structural loadings. Shearing deformations are recorded to failure. Peak and/or residual shear strengths are obtained from the measured shearing load versus deflection curve. Test results, plotted on graphical form, are presented on Plate A-I of this section. Consolidation (ASTM 02435) Data obtained from this test performed on remolded to 90% samples, were used to evaluate the consolidation characteristics of foundation soils under anticipated foundation loading. Preparation for this test involved trimming the sample, placing it in one inch high brass ring, and loading it into the test apparatus which contained porous stones to accommodate drainage during testing. Normal axial loads are applied at a load increment ratio, successive loads being generally twice the preceding. Soil samples are usually under light normal load conditions to accommodate seating of the apparatus. Samples were tested at the field moisture conditions at a predetermined normal load. Potentially moisture sensitive soil typically demonstrate significant volume change with the introduction of free water. The results of the consolidation tests are presented in graphical forms on Plate B-1. Expansion Index ASTM 04829 The site soils are comprised of silty fine to coarse-grained sand and are considered to have very low potential for expansion with an expansion index of (E.!. 12). Laboratorv Test Results Maximum Dry Density/Optimum Moisture Content Relationship (ASTM 01557-91) Sam Ie Location Max. B-llB-2, 0-5.0 feet 127.3 t. Moisture Content (%) 9.0 IPAGE 20 WAC Geotecbnical, Inc. 22- . <oj u z -< f- '" r;; <oj ~ " z i:a -< <oj :: '" . . DIRECT' SHEAR TESTS If) N f- o o (0, <oj ~ -< :l 0- '" ~ <oj ll. '" e: :.I: Q N "l - ,./ / c: _. If) = /'" Q o 0.5 1.0 1.5 2.0 NORMAL LOAD - KIPS PER SQUARE FOOT 2.5 . SYl\1BOL LOCATION DEPTH (ft) & 13-( 0-5 TEST CONDITION COHESION FRICTION RfMOL.oeO roqO% (pst) (degrees) SATvA!*TE()tO!l.flIIJe()"iO 30 PROJECT NO. 00576 WAC Geotechnical, Inc., P.O. BOx 354 PLATE A-I 39210 North Shore Drive, Fawnskin, CA 92333-0354 2h CONSOLIDATION TESTS . ." LOAD IN KIPS PER SOUARE .5 .6 I 2 3, 4 6 8. .10. . IS; 20 30' 50 , ", , :11 " !:. , , " III' , , u' , " , ~ " If" ',:, " , , , , " , , ,I " " " ,. " I 2 , , , , " " 3 " " 4 " , " Z 5 " , 0 , , I - ., I- " , < 6 C , " " - Iii .u , " CD 7 ," " '" I' " ,It Ii' " en " Z to' <D 8 " " , U , '11' iI, I" " I- 9 " " ' ~ " ,:; , Z " ." of , , , , II' ,,' ,,' 'I. It, W JII, , -'II " '" 10 , '" , " ,,' U I," " 'liP ." ." , , " "I " a: II; ,'. " I:' " I , " " , W " , , " , , " , .a. II , " .1 I' " " " " " II.. , , , , , '" " '" 12 , ' ,;1 ' , I ~ , ;,1 , I , I 'I' 'Ii , .. II" , I'; 'I,' , 13 ", , " " " , " ., ,to ''',ll i." " i;,' " ,':f" , ,,, .., , I I' " ., I," 'I: 14 " I I' " I ill " I I " " :1. II " 15 " .. , , I , " ". , 'II I'll Iii I'll " j;" " , , I '" , , " I III I , , " " II: ..,; '" , I , , , '~. 16 B-2) 0-5' I. WATER PERMITTED TO CONTACT SAMPLE ReMO\..oeo To '10~() WAC GEOTECHNICAL, INC. PROJECT NO. OO,? b P.O. Box 354-39210 North Shore Drive PLATE (3-1 Fawnskin, CA 92333-0354 800-288-0707 Y\ Tract 3932, Lot 257 . . W.O. 00576 PROFESSIONAL LIMITATIONS Our investigation was performed using the degree of care and skill ordinarily exercised, under similar circumstances by other reputable Soils Engineering Consultants practicing in this general or similar localities. No other warranty, expreSsed or implied, is made as to the conclusions and professional advise included in this report. The investigations are based on soil samples only, consequently the recommendations provided shall be considered 'preliminary'. 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 borings. As in most major projects, conditions revealed by excavations may vary with preliminary findings. If this occurs, the changed conditions must be evaluated by the Project Soils Engineering Consultant and designs adjusted as required or alternate design recommended. The 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 engineers. Appropriate recommendations should be incorporated into structural plans. The necessary steps should be taken to see that the contractor and subcontractors carry out such recommendations in 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 due to natural process or the works of man on this or adjacent properties. In addition, changes in applicable or appropriate standards may occur from legislation or broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly or partially by change outside of our control. Therefore, this report is su~ject to review and should be updated after a period of one year. RECOMMENDED SERVICES The review of grading plans and specifications, field observations and testing by the geotechnical representative is an integral part of the conclusions and recommendations made in this report. If WAC Geotechnical, Inc. is not retained for these services, the Client agrees to assume WAC Geotechnical, Inc. responsibility for any potential claims that may arise during and after construction, or during the lifetime use of the structure and its appurtenant. The required tests, observations and consultation by the geotechnical consultant during construction includes, but not be limited to: a. Continuous observation, geologic mapping and testing during site preparation and grading, and . placement of engineered fill. b. Observation and field review offooting trench prior to forming, steel and concrete placement, , c. Consultations as required during construction, or upon your request. PAGE 21 WAC Geotechnical, Inc. 2.:5" Tract 3932, Lot 257 . . W.O. 00576 REFERENCES 1. Geologic Map of California, Santa Ana Sheet, Division of Mines and Geology, dated 1966 2. Fault-Rupture Hazard Zones in California Alquist-Priolo Special Studies Zones Act of 1972 with index to Special Studies Zones Maps, Department of Conservation, C.D.M.G. Spec, Pub. 42, revised 1997. 3. Uniform Building Code, 1997, Volume 2 4. Uniform Building Code, Maps of Known Active Fault Near-Source Zones In California And Adjacent Portion of Nevada (Map 0-34) PAGE 22 WAC Geotechnical, Inc. 2-G. : i I' ::i J'""". If. ," , . . I ......., t'. 1._ , I /t; l~ '.~ : I ~1.~.~ .~ I ~ WI'~ ~i . .1 f ~ ...:'1 \tm~ '~t .0& ._ ~ r ,nl~ '. !.~It' .. .. 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