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Home My WebLink AboutTract 30578MOOK & TUP • (17,V111601',r; - j( e010g1 tg I E. TRU5LOW AVE. FULLERTON, CALIF. 92631 PHONES (714) 525-0242 - 1213) 691.91W 7 1 L®EC 201968 December 16, 1968 Job No. 18-718 GP Mr. Ed Pearson E1V.;,'•;;?;'+rGE. L. Pearson & Associates GEOLOGY1551WestRedondoBeachBoulevard Gardena, California 90247 S E G T I Q N GRADING AND FOUNDATION RECOMMENDATIONS PROPOSED SALES OFFICE SITE, TRACT 30578, DIAMOND BAR 1OV& (, t« D.&,..A /a4 'S's This letter supplements our Preliminary Geology and Soils -Report for Tract No. 315D dated September 11. 1968 (Job No. 18-616). (All applicable por- tions of that report are included in this report). Boring 5 of the Septem- ber 11 report is located just outside the area to be graded (see plan). The site was explored further by test pits 133 and 136, and borings 29 and 41. All logs are attached. The area is underlain by Puente sandstone with interbedded silty shale. Bed- ding attitudes dip between 15 and 20 to the north, a structural configuration which has contributed to landslides in this vicinity. Subsurface exploration and topographic relationships show that the site is supported along beddin planes to the north and is therefore cons1dered_s_table. (See section A -A . The proposed grading will be restricted to cutting the top off the small knoll which will increase stability. We recommend that a building foundation setback be observed as shown on the attached plan. The area outside the setback line is considered suitable for paved parking. If this area is not paved, it should be overexcavated to a depth of 2 feet and compacted to form a blanket of low permeability. A fairly thick sandy clay soil has developed over the sandstone in the southern part of the area to be graded. This soil is considered expansive, therefore, it should either be removed to a depth of three feet below grade and replaced with non -expansive material in building areas, or precautions taken for expan- sive soils during building construction. Sufficientnon-expansive material will be available from the sandstone. It is understood that the material generated by the cut operations is to be placed as fill on the Recreation and Stable site in Tentative Tract No. 30577. This should be placed in accordance with recommendations contained in our report of December 11, 1968 (Job No. 18-717). OT' HE.+ OQFICES. WOOOLANO HILLS 12131 :3400220 13ACRAMENTO (916) 371-1690 . SANTA ROSA (707) LI 2-5290 December 16, 1968 Mr. Ed Pearson Job No. 18-718 GP -2- Nothing is known at present regarding structure location, type, or footing loads. However, bearing capacity is at least 2000 p.s.f. for continuous footings one foot wide and one foot deep. The design load should be con- firmed near the conclusion of grading when the soil conditions and foundation design are known. As noted above, expansive soils could be present in the pad areas. Selective grading could substantially reduce or eliminate this material. However, if the Final Report of Compacted Fill indicates the presence of expansive soils or selective grading is not performed, pre -saturation of slab areas, deeper than normal footings and reinforcement of footings and slabs will probably be required. Specific recommendations can be made when the grading is com- pleted and the degree and distribution of expansive soils are known. Don Clark sjh Attachments: (6) Figures Plan - Section A -A' Distribution: AddresseeMMr. Lee Wilcox Ae4AL - Reviewed by D. R. Brown Registered Civil Engineer 12066 Engineering Geologist INURE OPPO (npinners. (/en1,v1;t,, TEST BORING LOG U 1 TYPE, 24" Bucket Au er ELEVATION 980 BORING Ne Dark brown SANDY CLAY (Soil) 5 CL 10 ellow and gray CLAYEY to SANDY SILTSTONE with thin interbeds of tan medium of 15 SANDSTONE ,and SHALE N Tan and orange medium to coarse CLAYEY SANDSTONE with SANDY SILTSTONE,- N aE 20 about 60% SAND and 40% SILT and CLAY, fine bedded 25 N73E 2/N 30 35 NB7'E ESN 40 O O Uy W W= W 2 z QJ NppG_J O gU z{ a oW Logged By DWC Oats 7-5-68 1. Job No. Figure 1 O 100 TEST BORING LOG TYPF 24" Rurkat Annar FIFVATION orn BORING N2 90 Dark brown SANDY CLAY with root hairs and concentrations of caliche CL 5 Merges to brown CLAYEY SAND with fragments 10 of SANDSTONE SC Merges to tan and gray SANDSTONE WAVE 15 with minor SILTSTONE, highly fractured and weathered NoE 3v EE 20 s.1a 7r" 35 3 25 Brown and gray SILTSTONE with thin interbeds of SANDSTONE, bedding interspersed with broken fragments and blocks 5a 30Zos 7 Jo f Brown and gray SANDSTONE, locally very blocky, minor brown SILTSTONE 35 40 O HN W OO NN W W O W\ p W= 4 2 J Fx W W WO F s 5fppWU r a O v No° o. N a 4 LL Logged B DWC99Y Date 11-20-68 N O f Job No. 18-718 Figure 2 RIRRRR TRRFR oinceis. (/eJ/oolstc YIIs TEST BORING LOG W 1Oe TYPE 24" Bucket Auger ELEVATION 960 BORING N429-Cont. 45 ASW Landslide shear surface 2" of ground upr CLAYEY SILTSTONE with an abrupt surface 45W 50 separating the material below and a gradatio SO into lesser disturbed SILTSTONE above BLW 147 Dark gray and brown SANDSTONE, solid no fractures, micaceous,, thin layers of SHALEY 55 SILTSTONE Notes: 1. No ground water seepage 2. No caving N W o N W Z Z J Ua Z V_ O 1\II f O IA W= J U W W 2 Wism Logged By DWC Date 11-20-Cr o v aa. ? a w 4 a z o m y N o f Job No, 18-71B Figure 3 I11fIRRE &TRRFR Q;,»o,' /- Gist, er 10 TEST BORING LOG TYPE 24" Bucket Auger ELEVATION 933 BORING NQ 41 i Tan medium SANDSTONE with local concentrations of'CLAYEY.SILTSTONE fragments 5 2 2.5 1 10 an me um SANusIOML, massIve, friable, heavy caving 44011V Light brown SHALE with very fine SANDSTONE ZSW Tan fine to medium SANDSTONE with SHALE, 15 very broken, A/01 Fracture with 2' displacement fr cfvre at 17' 70 2Q..-A Gray, yellow and brown medium SILTY to CLAYEY SANDSTONE, massive, locally highly sheared 25. 10 2.5 2 Heavy caving at 26' 30 3 4 20 2.5 3 Tan SILTY SANDSTONE, distinct bedding WO t ^ N W F W AW Z 2 J J_ W Z U_ W a.J Q W 2 W R CM2 W g na 0' aZ a W W a z Logged By DWC Dare 10-8-68 N f Job No. 18-718 Figure 4 WAR s TRRU - 6,117rer:, • I/Rn1oalst TEST BORING LOG Ir 10468 TYPE 24" Bucket Auger ELEVATION 933 BORING N41-Cont. N65W Brown medium SANDSTONE, massive, SSE 45 locally very CLAYEY 50 4Sw Slickensided CLAY 9sw Tan and brown medium SANDSTONE, massive 55 nw 60 25E Tan to brown SILTY SHALE, highly sheared, 30 2.5 4 pulverized at 62', abundant slickensides with striations in dip direction, CLAYEY22M 19A(M 65 oE' 21 2.5 5 Merges nto brown SILTY SHALE with inter- bedded gray SANDSTONE in lenses and thin beds, slickensides and moist clay disappear Notes: 1)) No ground water 2) Caving at 10 and 26' 3 Bulk sample taken off spoils pile - (S-6) Z WO F _ j W O W 2 Z J QrT Y a V QQ'a ZZ U N cr f onor y W ZWJUa. 2i WJ FZWt: 4 Qix F- 0W LL s JfWo T OJ a a W a z Logged By DWC Date 12-8-6BNau0mNh0f Job No. 18-718 Figure 5 linriRF &Tup TEST PIT LOG TYPE 24" Backhoe ELEVATION T P.N2 133 CL Brown SILTY CLAY Orange and gray medium SANDSTONE with about 35% SILTSTONE, highly fractured and contorted, 140 A ro// aft) 5 bedding is not regularly distinguishable, appears to dip in down slope direction, zo abundant slickensides, disturbed caliche near top of pit 10 15 WY LL Z W i K WN a2 20 Z Q J 6N U Qd W i W• 1 u WWJ d H00 fW WNW N Jf cc i w o G E N" i uai W W F> 4 Logged By DWC Date 11-17-68 TYPE ELEVATION T.PN2 136 sM Dark brown CLAYEY SAND soil Tan medium SANDSTONE with thin interbeds of N87W gray SILTSTONE, bedding consistant7W NBIW 5 Massive tan SANDSTONE with chunks of bedded SILTSTONE irregularly distributed throughout, probably caused by intrafor- 10 mational disturbance during deposition 15 W F W N a 2 K C WO U 2 1y \ O J N y Jd Ja W LLLL Q 2F N OW fH Qd 8 O V Logged By DNC Date 11-17-68 Job No. 18-718 Figure 6 111n IRI-, & I PUP - 4inerrs • (/an%v /r UNIFIED SOIL CLASSIFICATION Pt OH I CH I MH I OL I CL I ML SC I SM SP I SW GC I GM I GP I GW Sands with fines Clean sands Gravels withfines Clean gravels Highly Silts and clays Silts and clays 12%fines 5%fines 12%fines I <5%ones organic Solis Liquid Ilmlt greater than 50 Liquid limit less thon 50 50/oSands -more than ° of coarse Grovels -more than $0 /o of Coarse fraction Is smaller than NQ4 sieve. fractionis larger than N2431eve. Fine grained soils Coarse grained soils More than 50 % is smaller than N9 200 sieve) More than 50% is larger than NQ 200 sieve) s i 133011 LIQUID LIMIT LABORATORY CLASSIFICATION CRITERIA Y GW and SW- C- greater than 4 for G W B. 6 for SW; Ca= oa%02 between I a 3. uDID 0 GP and SP- Clean gravel or sand not meeting requirements for GW and SW. GM and SM-Atterberg limits below line or P I. less than 4. GC and SG-Atterberg limits above "A' line with P. 1. greater then 7. Fines ( silt or cloy) Fine andMedium Coar Fine sand I sand I gravel Coarse IgravelCobbles Boulders Sieve sizes Classification of earth materials shown on this sheet is base tl on field inspection and should not be construed to imply laboratory analysis unless so stated. MATERIAL SYMBOLS Gravel M HPeat or organicmatterSand Fill material Silt Shale Clay Sandstone Sandy cloy or clayey sand Limestone Sandy silt or Metomorphic silty sand rock Silty clay or clayey silt Igneous rock LEGEND OF BORING e - I11•'. Bottom eof borin 1 3 Ige CONSISTENCY CLASSIFICATION FOR SOILS According to the Standard Penetration Test NQ of blows I Granular I Cohesive 0- 5 Very loose Very soft 6- 10 Loose Soft II - 20 Semicompact Stiff 21 - 35 Compact Very stiff 36- 70 Dense Hard 70 Very dense Very hard LEGEND OF PENETRATION TEST 15 24 30 35 11 G. WS. 5 27 38 48 BI s perfo t o o a B. PF Us g I lb ho me wit 10 Graphic representation < 301 drop 3 0 driving rate. ft/ Ib bl W) 11 Legend