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Home My WebLink AboutCT 81-10; Carlsbad Research Center Phase I; Foundation Investigation; 1984-10-03SAN DIEGO SOILS ENGINEERING, INC. SOIL ENGINEERING & ENGINEERING GEOLOGY -. - -~ - -~ -~ - -. - -~ Cctober 3, 1984 F-sInsuranceGroq~ 4680 Wilshire Boulevard Los Angeles, California 90010 Job No: sD1315-00 ILJCJ No: sD4-3077 Attention: S-Z -: Gerltlemen: Mr. James V. Grizzell, Jr. EWNDATICW INVFSTIGATIau FamarsInsuranceGroup Regional office Building and ENGINEERING DEPT. LIBRARY City of Carlsbad Claims Office Building 2075 Las Palmas Drive L&s 4, 5 and 12; Tract 81-10 ScUthWest0xnerofRlCauli.noReal Carlsbad, CA 92009-4859 andFaradayAvwue Carl&ad, California "As-Graded Geotechnical Report, Rough Grading Canpleted,CarlsbadReaesrchCenter,PhaseI, Carl&ad Tract No. 81-10, Carl&ad, California", by San Diego Soils Rnginearing, Inc., dated April 21, 1982 (Job No: 1144-10) This report presents the results of our Foundation Investigation at the subject site. (xlr investigation was performed in August 1984, and consisted of field exploration, laboratory testing, engineering analysis of the field and labora- tory data, and the preparation of this report. SITE DBmIPrIa The subject lots are bonded by Priestly Driveon the uast, Faraday Avenue on the north and El Camino Real co the east as shwn on the Location Map, Figurel. The site is a portion of Car&bad Reswrch Center, Phase I, and includes lots 4, 5 and 12. These lots are presently flat graded pads (see referenced report) with a 3-foot high, 2:l (horizontal:vwtical) fill slope between the lots and variable height fill slcpss along the -tern, southern and eastern property boundaries. The boundaries of the lots have hem landscaped along the streets mantioned above. The site has been graded to drain gently to the northwest. SUBSIDIARY OF lR"lNE CONSULTING GROUP, INC. 4891 MERCURY STREET. SAN DIEGO, CA 9211 l-2190. (619) 268-8266 - - - - - ..- - - -- - - - - - - - Farm~~I!~~anceGroUp october 3, 1984 Job No: sD1315-00 Log No: sD4-3077 Page mm The site has been previously graded under the testing and cbservation of this office. The results of our testing and observation are reported in the referenced As-Graded Geotechnical Report. The site location and approximate boundaries are shmn on our attached site Location Map, Figure 1. PROPCGEDD- Proposed developmsnt consists of one one-story steel or mcd-frame building, and one three-story steel-frame building with slab-an-grade fleers and adjacent paved parking. Fill slopes to an approximate height of 5 feet are planed at the site. No detailed structural plans mre available at the time of this report. Hmever, a foundation scheme of continuous and isolated pad footings is antici- pated. The estimated foundation design loads, as shmnin the table belw,were provided to us by lbn Atkinson of Atkinson, Johnson aud Spurrier. Buildinq l-Story Foundation Design Icads Anticipated Continuous Ebctinqs Colurms Tvpe of bundation 1.5 k.1.f. 20 kips Ccmenticml Spread Footings 3story ---- ll40 kips* Cast-in-place Caisson * Includes 700 kips Seismic Icad Grading for the site will involve fine grading the building pads, pavsd parking areas, and construction of fill slopes. Gradingmay alsote required to provide appropriate site drainage. - - - - - - - - - Farmr~InsuranCeGro~p October 3, 1984 JcbNo: sx315-00 Log No: SD4-3077 Page lhres FIELDEmAxAmoN Subsurface conditions ware explored by drilling 5 borings to depths of 10 to 19 feet. The approximatelccations of theborings are shown co the attached Plot Plan,Plate 1. The boringsweredrilledwith atnack-munted 30-inch diameter bucket auger. Drilling of the test borings was supervised by cur field geologist who logged the soils and obtained bulb and relatively undisturbed san@es for laboratory testing. LAmRAmRY TmTItG A. Classification Soils ware classified visually according to the Dnified Soil Classification SyStgn. Classification was supplemsnted by index tests, such as Particle Size Analysis, and Atterberg Limits. Moisture content and dry density determinations were made for representative undisturbed saqles. Results of noisture~msity deteminations, -ether with classifications, are slxmn on the Jags of Borings, Figures 5 through 9. B. Particle Size Analysis Particle size analyses, consisting of sieve tests ware performed on representative san@es of the site subgrade soils in accordance with ASlM: D 422-63. Test results are shcm on Figures 10 through 12. C. Atterberg Limits Atterberg limits tests consisting of l&quid limit in accordance with A!ZlM: D 423-66 and plastic limit in -rdance with ASIA: D 424-59 ware performd on representative sanples of the co-site soils. The test results arepresented on Figure 13. - - - Farmers InsuranceGroup October 3, 1984 - - - - -. - - - - - - .- - JobNo: SD1315-00 Iog No: SD4-3077 Page Four D. E. F. G. H. Expansion Rxpansion tests ware performed co representative samples of the m-site soils remolded and tested uuder a surcharge of 144 pounds per square foot in accordance with the Mifonn Building Cede Standard No. 29-2. 'Ihe test results are smnarized 01 Figure 14, Table I. Max- Density/D&mm Misture Content The mwimm dry density/optimum moisture content relationship was determined for a typical saqle of the co-site soils. lhelaboratorystandardusedwas ASlt4: D 1557-78. The test results are smmrized co Figure 14, Table II. Sulfate A sulfate test was performed on a representative sauple of the on-site soils. The laboratory standard used was California 417 A. lhe test results are presented on Figure 14, Table III. R-Value An R-Value test was performed on a representative sa@e of the co-site sur- face soils. The laboratory standard used was ASTM: D 2844-75. The test results are sumnarized cn Figure14,Table IV. Direct Shear Direct shear strength tests ware performed co representative undisturbed sample.9 of ths on-site soils. To simulate possible adverse field conditions, the sa@es ware saturated prior to shearing. A saturating device was used which permitted the samples to absorb misture while a constant load is applied. The test results are presented cm Figures 15 and 16. - -- - - - - - - - - - - - .- FarmsrsInsuranCeGroup october 3, 1984 Jobho: SD131500 Iog No: SD4-3077 Page Five I. Consolidation Consolidation tests were performed on representative undisturbed sanples of the underlying bedrock materials to help determine canpressibility characteristics. Ihesanplesweresaturatedmid~ythroughtheteststo simulate possible adverse field conditions. The test results are presented on Figures 17 through 19. SUBSURFAClIcoNDITICNS A. Fill Carpacted fill was encountered in our exploratory borings 1, 2, 3 and 4 to a maximum depth of approximately 9 feet. In general, the fill soils are mist, stadium stiff to stiff, sandy clay and msdim dense clayey, silty sand. The surficial fill soils (18-inch 5) are dry, and thus need to be processed prior to placing any new fill (See page 8, part B). The surficial fill soils exhibit a sodium expansion potential. B. Bedrock Point ~cma Ebrmation consisting of moist, stiff to hard silt&one and very dense sandstone underlies the site. Bedrock is exposedatthe surface in the l-story building pad area. In the 3-story building pad area, bedrock was encountered approximately 4 to 9 feetbelawthe existing grade. The bedrockmaterials exhibit amsdiumwpansion potential. C. Groundwater and Caving No groundwater or caving of the borehole sidewalls was encountered during our field exploration. - - - - - - - --. - - - - - - - - - FarmsrsInsuranceGro~p october 3, 1984 JcbIUo: SD1315-80 Icq No: sD4-3077 Page Six D. E. Perched groundwater due to rain aud irrigation may be anticipated in shallm bedrock areas underlain by the fill. Aperimater drain systembelmthe concrete slab is recamwded. Iiard Drilling Hard drilling in the bedrock materials was ~ienced during cur explora- tion. Similar conditions may bs experienced during drilling for caissons. Expansive Soils The results of expansion tests indicate that the m-site soils exhibit a medimexpansion potential. Expansion of near-surface soils coulddamage structures and exterior flatwork. Recammndations to mitigate the affect of expansive soils co prcposed inprovsman ta are included herein and should be incorporated in project planning and design (Ses page 8, Part B). SEISMICITY A. Regional Seismicity W sitecan be considered a seismically active area, a9 can all of Scuthem California. There are, however, no knm active faults co or adjacent to the site. Seismic risk is ccnsideredlow, as aspared toother areas of southern California, due to the distance fran active faults. Seismic hazards within the site can bs attributed to ground shaking resulting franwents on distant active faults. ListedcmTable I are the active faults which can significantly affect the site. Figure 2 shows the approximate geographic relationship of the site tc these faults. - - - 0 2000 4000 ADAPTED FROM U.S.G.S. 7.6’ ENCINITAS & FEET SAN LUIS REY QUADRANGLE (1976) LOCATION MAP OS NO.: 1315-00 DATE: SEPTEMBER D l9S4 FIOURE: , SAN DIEQO SOIL8 ENQINEERINQ. Ih FarnksrS Insurance Group october 3, 1984 JcbNo: SDl315-00 kg No: sD4-3077 Page Sevfm B.Ea&hW&eEffects 1. Earthquake kcelerations We have analysed the estimated earthquake accelerations at the site and, in our cpinim, for the intended use, the mxt significant event is a 7.0 Magnitude earthquake located on the Elsinore Fault Zone. The anticipated accelerations produced at the site by such an eventmuld exceed these events which might cccur ~1 other lamwll active faults. AMagnitude 7.0 earthquake on the Elsinore F'ault Zone couldproducea peak ground acceleration of 0.18g at the subject site with the duration of strong shaking exceeding 30 seconds. Peak accelerations are not, hrmaver, representative of the accelerations for which structures are actually designed. ~ignofstructuresshouldbeinmrpliancewiththe requirements of the governing jurisdictions and standard practices of the Structural Rqineers Association of California. - - - - - - - - -~ - - ,- - - -~ .- FsTm DISTF!K!E FRcEmIE w EAurmJml FEAKEmRxK FRCMSITE rJDxtmmm2 Elsinore 22 Miles NE 7.0 0.18g Nmport/Inglewwd 40 Miles tW 6.5 0.06g San Jacinto 45 Miles NE 7.5 O.llg San Andreas 66 Miles NE 8.0 0.09g 1. Seismic Safety Study City of San Diego (1974) & Bcnilla (1970) 2. Schnabel & Se& (1973) - .._~ -~ .- .- - .- - .- ,> - - - FarmarsInsuxauceGro~p October 3, 1984 JobNo: SDl315-00 Log No: SD4-3077 Page Eight CCWLUS1ms ARDREmmmmTIoNS A. Meral The proposed constructicm is feasible fraa a soils engineering standpoint. The grading and foundation plans should take into account the appropriate soils engineering features of the site. The major constraints at the site are: 1) qxmsive soils: and 2) hard bedrock. 8. Site Grading 1. Site Clearing The site should be cleared of existing vegetation, Roles resulting fran the remval. of any buried cbetructicns, which extend belaw finished site grades, should be backfilled with ccspacted fill. 2. Preparation of Surface Soils The dry surface soils within the building area and to 5 feet beyond should be removed to a minimum depth of 12-inches below existing grade prior to placing any new fill. Areas to be paved with asphaltic concrete should be scarified to a minimum depth of E-inches below the existing grade. The actual depth of removal should be evaluated by the Geotechnical Consultant at the tine of grading. Prior to placing fill, the expoeed subgrade soils should be scarified to a depth of 8 to 12 inches, brought to near optimm moisture conditions and carpacted to at least 90 percent relative caqaction. 3. Remedial Grading (i) General The results of our testing indicate that co-site surficial fill soils and bedrock exhibit medium potential for expansion. Tb mitigate the - .- - - - - - - - - Farmers Insurance Group cctober 3, 1984 Job No: SD1315-00 kg No: SD4-3077 Page Nine expansion potential of these seterials on at-grade slabs, two alter- nativemethods are presented below: (ii) Moisture Conditioninq Fcur to g-feet of fill was encountered in the 3-story txlilding pad. During grading, the upper 18-inches of the fill soils within the building pad should be overexcavated and placed at 5 percent above optinrnnnoisture content. Bedrock consisting of Point LAM Formation is exposed at the surface in the l-story building pad. It has bean our ixperience that mitiga- tion of expansion potential by pre-soaking prior to pouring slabs in cut areas underlain by the Point Mna Formation is difficult to accceplish. Therefore, we recarmend that an areaextending [j-feet beyond the proposed buildings be excavated to a depth of 12-inches below existing grade, brought to 5 percent above cptinrna moisture content and recanpacted to 90 percent relative carpaction. This alternate may eliminate pre-soaking in the slab areas if the moisture content of the subgrade soils is mintained prior to placinq visgueen. (iii) Selective Gradinq The expansive potential of the on-site soils may be mitigated by selective grading. If this alternative is selected, wa rexsuerd that building areas and to 5 feet beyond in each direction bs capped with a minti of 2 feet of non-expansive W.B.C. Eqxnsion Index less than 20) soils. This alternative will reduce foundation cc&s in that foundations any then be designed for non-expansive soil con- ditions. - _~~~ -~ - ,- .- Fills constructed on natural slopes steeper thau 5:l (horizontalxertical should be keyed and benched into bedrcck or carpeteut natural ground. Canpaction of slopes should be achieved by overbuilding the slopes laterally and then cutting back to the cmpacted core at design line and grade. Although overbuilding and cutting back is the preferred method, fill slopes may be back rolled at intervals not greater than four feet as the fill is placed, followed by final canpaction of the entire slopes. Feathering of fill wer the tops of slopes should not be permitted. Fills should also be placed aud all grading perfomed in accordance with the requirements of the City of Carl&ad and the Uniform Building Code. 5. Imoort Fill Material - - ,- Farmers InsuranceGroup October 3, 1984 Job No: SD1315-00 Log No: SD4-3077 Page Tm 4. Canpaction and Method of Filling Fill placed at the site should be an$)acted to a minimm relative ccmpac- tion of 90 percent, based on ASTM Laboratory Test Designation D 1557-78. Fill should be corrpacted by mechanical means in uniform lifts of 6 to 8 inches in thickness. Racks greater than 6 inches in dimension should not be placed within the canpacted fill. Any soils imported to the site for use as fill or subgrade materials should be predaninantly granular and approved by the Soils mgineer prior to inporting. Laboratory testing required for approval of inport sources may require 24 to 48 hours. The Soils mgineer should be notified of import locations a minimum of tm (2) days prior to its proposed use. 6. Shrinkaqe and Subsidence Shrinkage due to remxal and rmction of the on-site soils may be negligible. Subsidence of fill should ba on the order of O-l-foot W~dl. Subsidence in the bedrock areas should be negligible. These - - - .- - - Famsrs InsuranceGroup cetober 3, 1984 Job NO: SDl315-00 rag No: SD4-3077 Page Eleven are preliminary estimates whichmyvarywithdepth of removal, stripping loss, and field conditions at the tine of grading. Shrinkage and sub- sidence figures are considered to be rough estimates based on available geotechuical information and should be wnfirmsd in the field during grading. 7. Fill Sloes Fill slopes to a height of approximately 5-feet are planned at the site. We recammnd that fill slopes be wnstructed no steeper than 2:l OkxizontaLverticalj. Fill slopes so wnstructed will exhibit a factor of safety in excess of the generally accepted minimum engineering cri- teria of 1.5 for gross and surficial stability. Slopes should be planted as soon as pcesible after grading. Sloughing, rilling and sloping of surficial soils may bs anticipated if these slo- pes are left unplanted for a long period of tine, especially during rainy seasons. Erosion control and drainage devices should be installed in ccqliance with the requirewnts of the City of Car&bad. C. Foundation and Slab Recaanendations 1. General Cur investigation indicates that the existing surface soils exhibit a medium expansion potential. The following recammn dations are provided for the design of fwtings and slabs based on this expansion potential of the soils and and building loads. Cur recannendations are considered generally consistent with the Standards of Practice. The potential for favorable foundation perfor- mance can be further enhanced by maintaining uniform noisture conditions. .- -~ -- - - - - FamersInsuranceGroup october 3, 1984 Job No: SDl315-00 Icg No: sD4-3077 Page lWelve The footing configurations and reinforcement recoaasu dations herein should not be considered to preclude imre restrictive criteria by the governing agencies or by structural considerations. A Structural Ruginear should evaluate configurations and reinforceaeut requirsrents for structural loadings, shrinkage aud temperature stresses. 2. Foundations a. One-Story Ruildinq The recammded type of foundation to support dead and live loads for a one-story building is spread footings, either square or continuous. No footings should straddle a cut/fill interface. All footings should be founded entirely in bedrock. (i) Colums Calms may be supported on spread footings founded a minimm of 18-inches belaw 1-t adjacent finish subgrade. Reinformrent should be based cm structural loading. (ii) VJalls Exterior aud interior footings should be continuous and founded at least 18-inches belaw lowest adjacent finish subgrade. Reinforcement in exterior and interior footings should consist of a minimma of two No. 4 reinforcing bars, placed one at the tcp and one at the bottan of the footing. - _ -~ -~ - ,- - - - - - - - Farnisrs Insurance Group cctober 3, 1984 Job No: sD1315-00 Log No: SD4-3077 Page Thirteen If the structure is to be supported co isolated spread footings, a moisture cut-off wall should bepouradaround the perimeter of the building to a depth of 18-inches below lmst adjacent finish subgrade. (iii) slabs Slabs should be as designedby the Structural Kngineer based cn anticipated use and loading and basedon aK-value Mrbgradenrxlu- lus) of 100 psi-inch. As a guide, we are providing the following generalrecaman dations based upon the expansive nature of the cn- site soils. Slabs should be of 4-inch naninal thickness rein- forced with 6x6x10/10 welded wire nesh located at mid-height, and supported on concrete chairs. Slabs should be provided with 4-inches of rounded gravel or clean sand follcwed by a 6-xnil visgueen (or equivalent) moisture barrier. The moisture barrier should bs sealed at all splices and werlain by at least l-inch of clean sand. (iv) Pre-Soakinq Beneath Slabs Slab subgrade soils should bs soaked to at least 5 percent above optimum moisture content to a depth of 12-inches belw slab subgrade prior to placesrant of concrete. The tmisture penetration should be verified by the Soils Engineer prior to placing visqueen. AS an alternate to pre-soaking, selective grading as recannended earlier my be elected. If selective grading is elected, we recanssnd that slab subgrade soils not be allowed todryback. In order to maintain the desired moisture prior to pouring slabs, periodic sprinklingrnaybe necessary. - - - - - - FarmrsInsuranceGroup October 3, 1984 Job No: SDl315-00 log No: SD4-3077 Page Fourteen b. Three-Story Building Due to heavycolunnloads (carpression and uplift), the recamwded type of foundation for the three-story building is cast-in-place drilled caissons deriving their support fran end bearing resistance between the pile tip and the supporting bedrock. (i) Allcmble End Eearinq Capacity The allowable end bearing capacity per caisson is given in the following table. Minimum Allowable Capacity Caisson Iength Caisson Diameter 1hdBearinq) (ft) 24" 300 kips 16 30" 550 kips 20 The above caisson capacities my be increased by one-third to resist wind and seismic loads. The structural capacity of the caisson should be determined by the Structural hgineer. (ii) Allmable Uplift Capacity The allowable uplift capacities of the drilled caissons is pro- vided in Figure 3. The caisson capacities presented in Figure 3 may be increased by one-third to resist wind and seismic forces. (iii) Lateral Bearing Capacity The allowable load capacity and themaxjmunbendirqnrnwtof a single drilled caisson with a fixed head due to a horizontal lead imposed at the top of the pile are given in the following table for a f-inch deflection. - r? -~ _~ -. -. - - - - - - - - - - - - ‘34 DIAMETER W 5 24’ DIAMETER : i!i 60 _ 50 100 150 200 250 300 UPWARD CAISSON CAPACITY (KIPS) CAISSON CAPACITY FARMERS INSURANCE GROUP OS NO.: 1315-00 DATE: FIQURE: 3 SAN DIEGO SOILS ENGINEERING. IN t -~ -. -~~ -. .- - - - - - .- - - Farmsrs InsuranceGroup October 3, 1984 Lateral Butt Capacity Diameter per Caisson 24" 19 kips 30" 27 kips (iv) Group Action of Caissons Job No: SD1315-00 Log No: SD4-3077 Page Fifteen laGmum Sending bbnent at TCQ of Caisson 137 kip-ft 233 kip-ft Point of Zero Wmmnt fran Top of Pile 26' 31' No reduction in caisson capacity due togroup action is required if the center tocenter spacing is equal toor greater than three tims the caisson diameter or width. Ebr any spacing less than three times the caisson diameter or width, caisson capacity (canpression and uplift) must be reduced to account for group action. Caisson reduction factors can he r ecammnded by this office. (v) Caisson Drillinq Cast-in-place drilled caissons should &end at least 5-feet into fresh bedrock. Since caissons have been designd to derive sup- port fran side friction and end bearing, every endeavor should be made to clean out the bottan of the bore hole prior to placing concrete. Caissons drilling should be observed by the Geotechnical Ccosultant. Hard drilling in the bedrock materials was experienced during cur exploration. Similar conditions ney be mienced during caisson drilling. (vi) Slabs Slabs shouldbe as design& by the Structuralmgineer basedon anticipated use and loading and based on a K-value (subgrade mndu- c -~ - - - - - - - - .- - - F?umsrs Insure Group October 3, 1984 Job No: SD1315-00 Icg No: sD4-3077 Page Sixteen lus) of loo-psi-inch. As a guide, wz are providing the following general r ecarmendations basedupon thewsivenatureof theon- site soils. Slabs should be of 5-inch nminal thickness rein- forced with 6x6clO/lO welded wire mesh located at mid-height and supported on chairs. Slabs should be provided with 4-inches of roundd gravel or clean sand followed by a 6-mil visqueen (or equivalent) moisture barrier. The moisture barrier should be sealed at all splices and overlan by at least l-inch of clean Sand. (vii) Pre-Soakinq Beneath Slabs Slab subgrade soils should be soakedtoatleast5 percent above optinnm moisture content to a depth of 18-inches belaw slab subgrade prior to placement of concrete. The moisture penetration should be verified by the Soils hgineer prior to placing visqueen. As an alternate to pre-soaking, selective grading as recamranded earlier my be elected. If selective grading is elected, we recauuend that slab subgrade soils notbealllmed todryback. In order to maintain the desired moisture in the subgrade soils prior to placing concrete, periodic sprinkling may be necessary. 3. Exterior Flatwork Provided sane differential novemmtcan be tolerated, exterior slabs on grade (i.e. patios, walkways) may be 3.5-inches in thickness and rein- forced with 6x6-10/10 wire mesh. A 4-inch granular base should be pro- vided belaw the slabs. Although pre-soaking is not a requirmant, moisture content of optimum or above should be maintained prior to place- ment of concrete. Slabs should be appropriately jointed for crack control. - Faxmen Insuran~Group october 3, 1984 Job No: SDl315-00 I&l No: sD4-3077 Page Seventeen -~ -, - - - - - - - - - - - 4. Allowable Searing Pressure for Footings The follming table gives the allowable bearing pressures for footings either entirely founded in cuqxcted fill or bedrock. Allcxmble Searing Pressures Soil Live Plus Dead Loads (psf) Canpacted Fill 2000 Bedrock 4000 A one-third increase for short-term wind or seismic loads may be utilized. Footings should have a minimm width of 18-inches and, where located adjacent to utility trenches, should extend below a one-to-me plane projected upward frm the inside bottaa corner of the trench. 5. Lateral Load Resistance The follcruing table provides the lateral bearing capacities for the ccmpacted fill and bedrock. Allowable Latera1Cp.c.f.) Allcwable Friction Soil F3earinq Pressure Coefficient zziEzd Fi11 300 0.30 600 0.30 6. Pcst~sioned Slabs As an alternate to conventional foundations, post-tensioned slabs may be used. Although typically more expensive, post-tensioned slabs have au excellent perforce record in expansive soil conditions. a. Eesigh Criteria Past-tensioned slabs should be designed by a Structural hgineer for a relatively uniform bearing over the slab area. The differential novsmmt rmded for design purposes is a two percent gradient in 10 feet horizontal. .~- - -_ .- - - - - .- Farmers InsuranceGroup octder 3, 1984 Job No: SD1315-00 Icg No: SD4-3077 Page Eighteen 7. b. Sutqrade Treatment Post-tensioned slabs in living areas should be underlain by a lO-mil misture barrier with one-inch of clean sand plaCea between the slab and moisture barrier. The barrier should be sealed atallsplices andcare should be t&en nottopuncture the barrier during construction. c. Thickened Ease Post-tensioned slabs should have a thickened perimeter edge extending at least 12-inches into the slab subgrade soils. Retaining Walls Restrained aud cantilevered retaining walls may he designed in accordance with the following design criteria. Backfill Soil Type Active Pressure, pcf Restrained Walls Cantilevered Walls Level Backfill 2:l Backfill Level Backfill 2:l Sackfill On-Site Soils Inport Select Sands (Sand equivalent greater than 30) 60 65 50 55 35 48 30 43 Walls subject to uniform surcharge loads should be designed for au additional uniform lateral pressure equal to one-third the anticipated surcharge pressure in the case of cantilevered walls, and one-half the anticipated surcharge in the case of restrained walls. Wall design should also consider surcharge fran any adjoining structures or traffic located within a zone defined by extension of an imaginary 1:l line-up frcm the level of the wall footing. .,- ._,~ .~- - - - .- - - - Farmers InsuranceGroup October 3, 1984 Job No: SDl315-00 log No: sD4-3077 Page Nineteen Retaining wall footings should be founded at a minimum depth of 24-inches below lowest adjacent grade. Ebr setback requirements, see section entitled "Footing Setback" Footings should be reinforced as recmmanded by the Structural mgineer. Flooding or jetting of backfill should not be permitted. Rackfill placed behind the walls should be mnpacted to a minimm relative ccspaction of 90 percent as determined by FslM Test Method D 1557-78. It should be noted that the use of heavy canpaction equipment in close proximity to retaining structures can result in excess of wall mvsment (i.e., strains greater than those normally associated with the developnsnt of active conditions), andwall pressures exceeding designvalues. In #is regard, the contractor should tie appropriate precautions during the backfill placement. If granular backfill is used (See Figure 20), it should be capped with 2-feet of relatively inpervious fill to seal the backfill and prevent saturation by run-off due to rainfall or irrigation. 8. Pcotinq Setback If footings areproposedadjacentto slope areas,we recamm dthatthe footings be deepened to provide a minimm horizontal distance from the outer edge of footings to the adjacent slope face. The rWed setback fran the slope face is as follows: Footing &+ba& = Heiqht ;f the Slope (minimum 10'; maximma 20'1 Footings planned under the influence of this recamm daticn should bs provided specific review by the Geotechuical Ccosultant prior to construction. Farmers Insurance Group cctober 3, 1984 Job No: SD1315-00 Icg No: SD4-3077 Pagemty 9. Expected settlenwt ,~~ .-. :\ ii 'ji If footings for the one-story building are supported by natural ground and are sized for the r mded bearing pressure, and the three-story building is supported M caissons, differential settlements are not expected to exceed t-inch. D. Type Cmznt for Construction The results of our sulfate testing indicate that cement m I or II may be utilized for caent in contact with the subgrade soils. - E. Drainage 1. Surface Drainage - .- - - - .- - - To enhance future site performance, it is recamended thatallpsd drainage should be collected and directed away fran proposed structures to disposal areas. For soil areas, we reomaend thataminimmoftwo percentgradientbemintained. he to the expansive natureof the cc- site soils, it is important that drainage be directed away fran foun- .- dations and that reccsmmded drainage patterns be established at the time of fine-grading and mintained throughout the life of the structures. Property cmers should be aware that altering drainage patterns, landscaping, the addition of patios, planters, and other inprovemnts, as well as irrigation and variations in seasonal rainfall, all affect sub- surface moisture conditions, which in turn affect structural performance within wsive soil areas. 2. Subsurface Drainaqe Although no groundwater was encountered in any of our test borings, perched groundwater due to rain and irrigation may be anticipated at the fill-bedrock interface. We recammdthatasubdrain systembelcwthe concrete slabs of three-story building be prwided to mitigate the effect of potential perched groundwater condition. The subdrain system should be designed by the Civil ?&gineer. Furs InsuranceGroup october 3, 1984 .,- ,.- _- .- - _- - Job No: SD1315-00 Iog No: SD4-3077 Page lMeuty-&e F. Trench Rackfill It is our opinion that utility trench (exterior and interior) and/or wall backfill consisting of the ou-site material types could be best placed by mechanical caxpaction to a minimum of 90 percent of the laboratory maximm density. If the trenches are excavated in the bedrock neterials, oversize material my begenerated aud not te suitable for backfill. Norocks greater than 6-inches are acceptable for trench backfill, and nesting of rocks less than 6-inches should not bs allowed. G. Gradinq and Footing Observations Grading should be performed under the testing and observation of the soils engineer. Pdaitionally, all footing excavations should be reviewed by the Soils mgineer prior to placing reinforcing steel and concrete. H. Paved Areas Areas to be paved with asphaltic concrete should be graded in accordance with the site preparation recanusndations given above. Pavemeut subgrade soils should be scarified and moistened to near cptimm conditions and cmpacted to at least 90 percent relative ccspacticn in the top 8-inches below finished subgrade imediately prior to placing base. The following preliminary pavement sections are recomen ded based on au R-value of 29. Light Vehicles 3-inches of asphaltic concrete wer (T.I. = 4.5) 4f-inches of untreated Class II aggregate base Driveways and 3-inches of asphaltic concrete wer truck loading 8-inches of untreated Class II aggregate base (T.I. = 5.5) Farmers Insurance Group Cctober 3, 1984 Job No: SDl315-00 rag No: sD4-3077 Page'Itrenty+m These preliminary r ecammdations should be confirmed by additional R-value testing at the ccqleticn of fine grading. Aggregate base shouldconfonto the requirements of the California Department of Transportation Standard Specifications for Class II aggregate base. Aggregate base should be ccm- pacted to a minimum of 95 percent relative canpaction. We recammnd that the area within and around the trash enclosurebepaved with Portland Cement Concrete. P.C.C. paving should be a minimum 5-inches thick, reinforced with 6x6xlO/lO welded wire mesh. Subgrade soils should be prepared as recarmend ed above for asphalt paving. Concrete paving should be provided with appropriate release joints at a maximum interval of 20-feet - and divided into a nearly square panels as possible. - SUMARY - -, As foundation and grading plans are carpleted, they should be forwarded to the Soils Engineer for review for conformance with the intentions of these recannendations. - - - - - - - - .- _- .- - - - - Fanners InsuranceGroup October 3, 1984 Job No: 911315-00 I&g No: SD4-3077 Page 'ItJenty-Ihree LIMITATIONS OF INVRSTIG&TIoN Our investigation was perfomed using the degree of care and skill ordinarily exercised,under similar circun&ances,by reputable Soils Bgineers and Geologists practicing in this or similar localities. No other warranty, expressed or i@.ied, ismade as to the conclusions and professional advice included in this report. The samples taken and used for testing and the observations made are believed representative of the entire project; however, soil and geologic conditions can vary significantly between borings and surface outcrops. As in nwst mjor projects, conditions revealed by excavation akay be at variance with preliminary findings. If this occurs, the changed conditions must be evaluated by the Project Soils hgineer and Geologist and designs adjusted as required or alternate designs recomended. This opportunity to be of service is appreciated. If you have any questions, please call. SAN DIEGO SOILS BJGIREERIX, INC. Tara S. Sikh, R.C.E 35454 Senior pgineer W.-Lee Vanderhurst, C.E.G. 1125 Manager,Geologic Services fi , . . . Vice President - - - - - - _- - -- - - - - Farmers Insurance Group October 3, 1984 Enclosures: Distribution: Location Map, Figure 1 Regional Fault Map, Figure 2 Plot Plan, Plate 1 Caisson Capacity, Figure 3 Lugs of Borings, Figures 5 through 9 Laboratory Test Data, Figures 10 through 19 Retaining Wall Backfill, Figure 20 (6) !hems/kwis & Partners Attn: Mr. Ramiro Hemandez Job No: SD1315-00 I@ No: SD4-3077 Page Mty-mur _ _~ - - - .- - - - - - - - - - - - PRIMARY DIVISIONS 7 7 mow BYM. SECONDARY DIVISIONS ,,3 - 1 GRAVELS 1 -Quv~~s 1 GW t! Nel raded Srnvets. grwel-sand mixtures. little or 2 0 x 2 y 1 %$$$I ““&%: ‘% ’ GP ‘;;:,:::i, lines, Poorly graded grwels or gr~rel-sand mixture8. . . Km GM ;l:‘&~.,#- a” GC “,r:rr:rc 91,‘1 FRAcnoNls QRAvEL% i-: -. Jrsl-sand-aill mlrturel, non- LARDER THAN ND.4BtEVE FUSS wts.prwet-•nd-clay mixtures. B6. SANDS CLEAN SAms SW v;isP’iId’d #ends. ~rwelly l rids. llttle or no LlQEnuNnALF ffwARBE ‘fE.ZY SP iZW,L?. ,.d.d mnds or g,.r.tty s.nds. llttle 0, FRAcnoN IB SM Silty undo. wnd-slit mixtures. non-plastic fines. 2 s BWULERTHAN =WtTH=S- No.4SEVE SC c~qey sand% smwi-clay mixturas.~~pI~8tIc fines. ML Inor~mdc slIta and ve, flns mands rock II our c.111 0, SILTS AND CLAYS clayey fine w!ds or c wey Ms whh 8Ilaht 7 plastlc ty. z LlDLmLuTLsLEss?HAN60% CL Inorgllnic c*ylJ of br to m&l” platiiclty. ~svelly CIW.. Bandy Clws, smty clays. elln clays. OL Orp8nlc alIts and orpwdc l llty ctws of low plasticit) SILTS AND CLAYS MH 1 kay m~I~I~#lta~,~;c*~~w~y; ?~MQl~tomweous fine wu)LmmlBQREAmFtmwJ607 CH 1 Inorganic clays of high plmsticlty. fat clays. OH gym& $ys of #n@dillm to hi@ HIGHLY ORGANIC SOILS . , I plasticity, 5. Pt Peat and other hlphly organic wlls. DEFINITION OF TERMS U.S. STANMRD SERIES SIEVE CLEAR SQUARE SIEVE OPENINGS 200 40 10 4 314’ 3’ 12. SILTS AND CLAYS SAND I GRAVEL FINE UEDIUM COARSE FINE COARSE COBBLES GRAIN SIZES SAN~S.ORAELB AND CLAYS AND NON-PUSTIC. SILTS BLOWS/FOOT’ PLASTIC SILTS STRENGTH’ 1 I VERY LOOSE VERY SOFT MEDIUM DENSE VERY STIFF VERY DENSE 7 o-2 2-4 lLOWS/FOOi 4-S a- 16 16 - 32 OVER 32 RELATIVE DENSITY CONSISTENCY t Number of blows of 140 pound hammer falling 30 kwhes to drtve a 2 Inch OD. (l-318 inch lD.l stayI sm (ASTM D-1bSS). ‘Ltnconfhed ccmwe~sive strength h tonslsq. fl. .a determined by bborexy teetog OT ~proxtmated by the stm,da,d pe,,et,ation test (ASTM D-1686). pocket penetrometer. torvm,e, or rluul ob.srv.ttc,n, KEY TO EXPLORATORY BORING LOGS Unified Soil Classification System (ASTM D-2487) >B NO: DATE: 1315-00 FIBURE: 4 -~ .~~~~ - - - .- - - - - - - - - .- - MTE OBSERVED: 8/20/84 METHOD OF DRILLING: 30" Bucket Anger 2600 lhs k~,,v-bavwv LOQGED By:c(: GROUND ELEVATION: 317 ' LOCATION: see mao i: it g gafi Y s 0 mu! = && Rd a Yg f$ BORING NO. 1 Y 2 C 2 2% ‘: z+ y- z’w <k cJ> SOIL TEST z 3 ze i r: 0 OfJJ 5 6 d 5 $5 2 0 2: 5; DESCRIPTION ,O / CL Fill: Brown fine sandy CLAY, dry, medium stiff. _.------_---..------ -___ --.__-__--_-_-__-__-____________________-- -CL 10 17.1 110.2 Brown fine sandy-y, moist, medium with gravel. 19.2 105.:Bedrock: Point Lana formation; light brown to gray-brown with orange and brown streaks clayey SILTSTONE, moist, very stiff to hard. Direct Shear (undisturbed1 Total Depth 18' No seepage, no caving Backfilled 8/20/84 SAN DIEGO SOILS ENGINEERING. IN{ -. _~ - - - -- - - - - - - - - - - IATE OBSERVED: e/20/84 METHOD OF DRILLING: 30” Bucket Anger ,OGGED SY:L GROUND ELEVATION: 317 ’ LOCATION: see ma0 BORING NO. 2 DESCRIPTION SOIL TEST __---__-__-_-_______-----..------------- Dark brown fine sandy CL&Y, slightly organic, moist, medium stiff to stiff, with some gravel. Consolidation (undisturbed) 1 x Atterberg Limits, Expansion, Sulfati Particle Sire 0 Analysis 11 2.3 107.1 Bedrock: Point Loma formation; light Direct Shear brown to gray with orange streaks (undisturbed) clayey SILTS'TOFE, moist, very stiff to hard, fractured. 5- o- @ 19' Cemented Refusal ,a 19' Total Depth 19' no seepage, no caving backfilled a/20/84 5- O- 5- O- WfY-00 LOG OF BORING FIGURE: G _... -.--- _-.. _ -..- ..- -- .._ . . SAN DEGO SOILS tNCilNttRIN(i. IN‘ _~~ -~~~ - - -- - - - - - .- - - - - - )ATE OBSERVED: 8/20/84 METHOD OF DRILLING: 30" Bucket Anger 2600 lb kelly hammer .OGGED By: cc GROUND ELEVATION: 319’ LOCATION: see map DESCRIPTION SOIL TEST maximum density, (undisturbed), ___-~_-_--__-_----__-------~~----~~~--- Particle Size Dark brown sandy mY,moist stiff, .Anal;;cis slifhtly organic. P7', dry. Lulisoiidatior~. IO- (undisturbed) Direct Si:car 14 19.5 107.‘ Bedrock: Point Loma Formation; light (undisturbed) brown-tan with orange and brown streaks clayey SILTSlONE, moist, very Cor:solidation stiff to hard, irdctureu. (undisturbed) 15- 10- @ 19'. Cemented Refusal @ 19' Total Depth 19' no seepage, no cav1nq backfilled 8/20/84 !5- IO- I5- ,o- -- ..^ -- ---...- -.-..-- yyJ&o I LOG OF BORING r,aunt: , SAN DIEGO SOILS ENGINEERING, IN{ -~ .~ -, -. - _- - - - - _- - - - - - IATE OBSERVED: 5/20/84 METHOD OF DRILLING: 30" Bucket Anger 2600 lbs kelly hammer .OQGED BY: cc GROUND ELEVATION: 31g’ LOCATION: see map i= E ii 5 GE 2 2 2! 2 wz gi t: 2 iii zg ;: is- w- BORING NO. 4 E l-2 0, 5 s %a <:t SOIL TEST ! r 0 003 3 2: d 5 2 ‘; ig z; DESCRIPTION 0 * CL Fill: Light brown-tan sandy, silty - -------------------.*** CLAy, dry, medim Stiff. . ML __--~___-__--__-_-__--~~-~~-~~~~~~~-~~~ - --- ____ -_- ____- ---- 8. Tan-light brown clayey, sandy SILT, *. , moist, medium stiff. 5- CL ------_-_-----_----------------------- Dark brown sandy CIAY, slightly organic, moist, stiff. @51, dry. Bedrock: Point Loma formation; light o- brown with orange and brown streaks clayey SILTS'JDNE, moist, very stiff, fractured. s- , Total Depth 10' No seepage, no caving o- 5- O- 5- o- ^_ ..^ “a I.+“.: 1315-00 I -- -- ---._.- LOti UF BUHING I -. ^ . - - r,uunc: g SAN DIEGO SOILS ENGINEERING, IN< - - - IATE OBSERVED: 8/20/84 METHOD OF DRILLING: ;;;oB;;k;:l;;imer .OGGED BY: Cc GROUND ELEVATION: 311 ’ LOCATION: see map F E ttl 5 $G : k : c 2!! I Yg ga z zg zJ St- - BORING NO. 5 l-2 z :: 2: - SOIL TEST z z E< 2 z cj $” 5 gg 6 m 3 : 0 2: 5: DESCRIPTION 0 Esedrock: Point Lam Fomtion; liqht brown to grey with Orarqe and brown streaks silty, SANDSTWJ, nuist, very dense fractured. 5- 16 22.7 103.: Atterberg Limits, Expansion, R-value Particle Size Analysis o- 3/g* 22.7 100.: @ 10 l/2', Cemented Refusal @ 11' Total Depth 11' NO seepage, no caving 5- o- 5- O- 5- O- -- ..- -._-- LJB No.: 00 I LOG OF BORING lw3”Rt: 9 SAN DIEGO SOILS ENGINEERING. INC I I 1 I I I I I I I I I I \ I / I SAND GRAVEL SILT CLAY COARSE MEDIUM FINE SIEVE SIZES-U.S. STANDARD 3/4" 112” 10 20 40 100 200 100 100 00 so 60 SO 70 70 ii 60 ?i = 50 2 z ii 40 II' G) -. 30 4F -tHtHt+i I II )I; I : I I I 20 20 10 10 0 0 10.0 1.0 0.1 .Ol ,001 PARTICLE SIZE-MILLIMETERS I? BORING NO. DEPTH (FEET) SYMBOL LIQUID LIMIT PLASTICITY INDEX CLASSIFICATION R-L 5 ZR- Ii CL 3 I I I I I I I I I I I I I I I I / SAND GRAVEL SILT COARSE MEDIUM CLAY FINE SIEVE SIZES-US. STANDARD 3/4” 112” 114” 4 10 20 40 100 200 80 2 60 i f 50 2 (I) L.? z 40 0 30 20 10 0 PARTICLE SIZE d.1 .dl -MILLIMETERS 60 fi 2 Ill 50 f 2 z 40 i - 30 20 IO 0 BORING NO. DEPTH (FEET) SYMBOL LIQUID LIMIT PLASTICITY INDEX CLASSIFICATION B-3 2 42 10 SF- I I I I I I I I I I I I I I I I I / SAND GRAVEL SILT CLAY COARSE MEDIUM FINE 3/4" 112" 114,; SIEVE SIZES-U.S. STANDARD 4 10 20 40 100 200 100 100 so 90 SO 80 70 70 60 60 50 50 40 40 30 30 20 20 10 10 0 I I I 0 10.0 1.0 0.1 .Ol ,001 PARTICLE SIZE-MILLIMETERS BORING NO. DEPTH (FEET) SYMBOL LIQUID LIMIT PLASTICITY INDEX CLASSIFICATION B-5 3 --- 50 13 s r.1 - - - - - - - - - .- - - - - - PLASTICITY CHART z z” E 3 I= : 20 i 10 7 ---- _--- O- 0 10 20 30 40 50 80 70 80 00 100 LIQUID LIMIT (%) SYMBOL BOFONG “,“,;; “i’,“,:,“” ‘;$? (FEET) ‘ONTENT (%) C%) PLAS- yoss;,“,” LICUIDITY UNIFIED TICITY SOIL INDEX &EVE INDEX CLASSI- (96) (%) (%) FlCATlOl SYMBOL 0 B--2 5 --- 28 15 72 CL 0 B-3 2 --- 42 10 38 --- s Ii m B-5 3 --- 50 13 36 --- SM ATTERBERG LIMITS 38 NO.: 1315.-00 DATE: FIGURE: 13 SAN DIEGO SOILS ENGINEERING, IN< -. - -~ -, - - - - - - - - - - - - - TABLE1 REsUL!EOFEWWSICNTWl'S (U.B.C. STMDARD 29-2) Test Location I I B-2 @5' 51 medium B-3 @2' 61 medium B-5 @3' 69 medium TABLE 2 MAXIM@3 DENSITY/OPTIMW M)ISTURS RELATIONSSIP (AS'IM: c-1557-70) ){ TABLE 3 SOLUBLE suLFATEa)mlmr TABLB 4 R-VALUETETRFSWl-S Test R-Value Location i/ I B-5 @3' I 29 I 1’ Job No: 1315-00 Figure 14 -~ - -~ - -. - .- .- - - - - - .- - - - BORING DEPTH NO. (FEET) CO(“,‘sON, ANQLE 0% FRICTION. ~+d,-~ -- nnrrn I 0 -- I 1000 1 34 m RPdlr bY”iJ L ,_ ---__ 6000 ix : z a ?I F 4000 m l3 r 2 : 2000 NORMAL LOAD (PSF) OB NO.: 13ij-00 NORMAL LOAD (PSF) SHEARING STRENGTH TEST FIQURE: i5 SAN DIEGO SOILS ENQINEERING. INC -~ _-, -, - -. - - .- - .- - .- - - - - .- 4030 3000 c 2 ? i! : r-J 2000 g E z 5 1000 C BORINQ DEPTH NO. (FEET) CO~pE$ON. ANQLE 0% SAMPLE DESCRIPTION FRICTION. B-3 I 5 [ 400 33 Fill, CL (undisturbed) NORMAL LOAD (PSF) s”tEQ DEPTH (FEET) CO$WPN. ANGLE OF, SAMPLE DESCRIPTION FRICTION. I I 4000 5001 3000 s 5 I- 6001 IO< 1 41 101 0 I 5f 101 3 NORMAL LOAD (PSF) OB NO.: 1315-00 SHEARING STRENGTH TEST FIGURE: 1G SAN DIEQO SOILS ENGINEERING. IN< I I I I I I 1. I I I I I I I ! i I CONSOLIDATION (%) I EXPANSION (%I 50000 I I I I ~~~ 100000 I ” I I - j ” r 1 i I I ; : ; ; : r : : i 1 , , I I , , , I I I i I ! ! CONSOLIDATION (%) I EXPANSION (%I 30000 40000 50000 100000 I I I I I I I I I I I I 1 I I ! I CONSOLIDATION (%) I EXPANSION (%I I _ _ -~~ .-~~ -.~ - _- - - - - - - - - - - T GRANULAR BACKFILL DRAEUOE A0 DE- BY (El COHESIVE BACKFILL bl, NO.: RETAINING WALL BACKFlLL (NOT TO SCALE) 1315-00 DATE: FIGURE: 2.