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Home My WebLink About480530-01; Home Plant Sewer Pump Station Storage Res.; Home Plant Sewer Pump Station Storage Res.; 1980-08-06SOILS INVESTIGATION FOR PROPOSED STORAGE RESERVOIR HOME PLANT SEWER PUMP STATION WEST SIDE OF CARLSBAD BOULEVARD NEAR INTERSECTION WITH STATE STREET CARLSBAD, CALIFORNIA August 6, 1980 Project No. 480530-01 Prepared for PI City of Carlsbad '—' Engineering Department 1200 Elm Avenue Carlsbad, California 92008 LEIGHTON and ASSOCIATES INCORPORATED SOIL ENGINEERING TESTING GEOLOGY August 6, 1980 ENVIRONMENTAL SCIENCES Project No. 480530-01 TO: City of Carlsbad Engineering Department 1200 Elm Avenue Carlsbad, California 92008 ATTENTION: Mr. David A. Hauser SUBJECT:Soils Investigation Proposed Storage Reservoir Home Plant Sewer Pump Station West side of Carlsbad Boulevard near Intersection with State Street, Carlsbad, California Gentlemen: This report presents the results of a soils investigation at the site of the proposed storage reservoir at the subject sewer pump station. Our investiga- tion was performed in July and August, 1980 and consisted of field recon- naissance, subsurface exploration, laboratory testing, engineering analysis and the preparation of this report. The purpose of the investigation was to provide recommendations for embankment stability, site grading and reservoir lining. Proposed Construction The proposed construction consists of an earth embankment storage reservoir having a depth of about 8 feet and overall dimensions of about 70 feet square. The reservoir will be constructed partly in cut and partly in fill materials. Present olans show an outboard embankment slope of 2 to 1 (horizontal to vertical) and inside slopes of 1 to 1. Site Description The sewer pump station is located west of the intersection of Carlsbad Boulevard and State Street and south of the Buena Vista Lagoon in Carlsbad, California (see Index Map, Figure 1). The proposed reservoir site is located 7290 ENGINEER ROAD, SUITE H, SAN DIEGO, CALIFORNIA 92111 (714) 292-8030 IBVIWE . WESTLAKE/VEMTURA • DIAMOND BAH/raALWUT • SAW BERNARDINO/RIVERSIDE « SAM DIEGO 480530-01 \*r \, \> -»x. Ar\\ \, \^ v .1 2000 scale FIGURE 1 feet HOME PLANT SEWER PUMP STATION CARLSBAD, CALIFORNIA BASIS: U.S.G.S. San Luis Rey Quadrangle LEIGHTON AND ASSOCIATES D 480530-01 at the north end of the Pump Station on a grass-covered north-facing slope having an overall inclination of about 5 horizontal to 1 vertical. An existing 100-foot diameter trickling filter is located at the upper south end of the property. Various sprinkler lines cross the reservoir site. Subsurface Exploration Our subsurface exploration consisted of drilling two 6-inch diameter test borings to depths of 25 and 26 feet. The approximate locations of the test borings are shown on the attached Plot Plan, Figure 2. Bulk and undisturbed samples of the subsurface materials were obtained for laboratory testing. Logs of the borings (Figures 3 and 4) are included with this report. Laboratory Testing Laboratory testing consisted of moisture content and dry density, maximum density, gradation, direct shear and consolidation tests. Results of the laboratory tests (Figures 5, 6, 7 and 8) are presented with this report. Subsurface Conditions Boring 1 which was drilled at the upper end of the proposed reservoir en- countered loose sands and silty sands to a depth of 6.5 feet underlain by a layer of stiff, sandy clay to a depth of 8 feet underlain in turn by very dense sands to the depth explored of 26 feet. Boring 2 at the lower end encountered loose, silty and clayey sands and clean sands to a depth of 18 feet underlain by very dense sands to the deptn ex- plored of 25 feet. No groundwater was encountered during drilling of Boring 1. In Boring 2 groundwater was encountered at a depth of 6 feet. A piezometer was installed in Boring 2 to allow future monitoring of groundwater. Groundwater levels are probably influenced by the adjacent lagoon. -3- 480530-01 CONCLUSIONS AND RECOMMENDATIONS D From a soils engineering standpoint the site is suitable for construction of the proposed reservoir provided the following recommendations are incorporated into the design of the project: A. Reservoir Cut Slopes Due to the looseness of the upper sandy soils the proposed reservoir cut slopes will be marginally stable at an inclination of 1 to 1. Accordingly, we recommend that cut slopes for the reservoir be constructed no steeper than 1% to 1 (horizontal to vertical). Alternatively, the slopes may be con- structed at a slope of 1 to 1 provided the outer portion of the slopes are recompacted to at least 90 percent relative compaction for a minimum width of 15 feet measured horizontally from the face of the slope. B. Recompaction of Surface Soils Because of the looseness of the surface soils, settlements on the order of 3 to 5 inches are anticipated beneath the weight of the fill embankment. To minimize settlements and the potential for cracking of the reservoir lining we recommend that the surface soils beneath the fill embankment and reservoir be overexcavated to a depth of about 5 feet (elevation 10*) or until further excavation is impracticable due to wet pumping soil conditions resulting from the high groundwater table. The excavated soils may be replaced as compacted fill. D some additional settlement is anticipated due to compression of materials below this depth but should occur relatively rapidly on account of the granular (free draining) nature of the materials. C. Earthwork Recommendations Prior to grading the site should be cleared of vegetation and surface and subsurface obstructions including buried sprinkler lines. The on-site soils are suitable for re-use as fill provided they are free of organic materials and debris. Any imported soils should be approved by the Soils Engineer. All fill placed at the site should be compacted to a minimum relative com- paction of 90 percent based on ASTM Test Designation D1557-70. Fill should be compacted by mechanical means in lifts not exceeding 6 inches in compacted thickness. Fill slopes should be compacted by sheepsfoot rolling or by overbuilding and cutting back. Volume shrinkage of about 15 percent will occur due to compaction of the surface soils. -4- 480530-01 D. Reservoir Lining The proposed 3-inch A.B.M. lining reinforced with 6x6-10/10 welded wire mesh '— ' is a suitable lining for the reservoir. To minimize the potential for cracking we do recommend that construction of the lining be delayed as long as possible following construction of the embankment. E. Inspection It is recommended that the project earthwork be inspected and tested by the Soils Engineer to verify conformance with these recommendations. This opportunity to be of service is sincerely appreciated. If you have '-' any questions concerning our findings, please call. Respectfully submitted, Martin R. Owen, RCE 23155 Chief Geotechnical Engineer MRO/pw Distribution: (4) Addressee -5- Scale 1" = 20' & CONTfl&L-V/ICE TRENCH: . - .--. LEGEND APPROXIMATE LOCATION OF TEST BORING PLOT PLAN RROJECT NO. 480530-01 LJ FIGURE NO, 2 LEIGHTON AND ASSOCIATES, INC, 7/9/80Date • Project Name Perilling Co. Hole Diameter Drill Hole No.5-1 Home Plant Sewer Pump Station Sheet i of Project No. 480530-01 Geo Drill 6"Drive Weight _Type of Rig Truck Mounted Flight Auger 140# Drop 3Q in. Elevation Top of Hole 26 +-'- Ref. or Datum MSLJ £ *^ 8* " "1 0 5 — ' 10 — 15 — 20 — 25 — • - 30 o • H P. Ort -J 0 4 • . ." • • • '$/ /•/•/?./s<//,-1 . .1. * 1 •J. . . . . . J. . . . : : • • » • * m « * * . * * * » • » • • % * ' • • * > . » . . .... .... .... .... • ... (/> CD T3 •P •H 4-> O 2 O D —I 03 W si/ 1 2 D 3 4 ^ "> ° a a. - i I 8 J 507 4 50/ 4 SO/ !J i 50/ 3 X •Htn i — » (U CJf ) pi, X< . Q 99.7 100.9 90.9 sample distur 107.2 °> -p§s^ ^^"J5 21.9 11.7 15.8 bed) 10.4 . w ^ ^ C/-u ^ o3 SM sc CL SP- SM SP SP d. GEOTECHNICAL DESCRIPTION Logged By SRH Sampled By SRH Brown, silty fine to coarse sand, moist, loose, grass roots in upper 1 foot Gray-brown, clayey fine to medium sand, micaceous, damp, loose Gray, sandy clay, moist, stiff Gray, silty fine sand, moist-, ; very dense Gray-white, medium-grained sand with shell fragments, moist, very dense Gray-white sandstone, moist, very dense Total Depth: 26 Feet No H20 - - - - - . _ - LEIGHTON and ASSOCIATES FIGURE 3 Date 7/9/80 Drill Hole No.B-2 Sheet Project No. of Project Name HQtne Plant Sewer Pump Station Fj Drill ing Co. Geo Drill T>Te of Rig Trurlc MountPd Flight fltjger Hole Diameter 6"Drive Weight Drop 30 in. Elevation Top of Hole 15 - Ref. or Datum MSL L 1i — IL cLJ C pL i— [ [ [ [ L r- L L C r jC *~** Q ^ 0 5 — 10 — - 15 — 20 — — - 25 - 30 o • H f (50cx on) -3 C5 • 1 - 1 • 1 • ,| . . . -|.|.|. •1 -1 ' I' / / / / //'/ A > Y/. •/•/• • . • / /• • * • * • » • • * f • • • • • * •- • * » * • • * • • * * * • * * * 0>•o 3•p•H •P 1* 0 xC. D •-< rt i 2 3 4 </i S^ ^ ,° ^ fO o. 1 1 5 i 4 50/ 4 SO/ 4 1 X -H(/> < — > <D O Q PL,v — y X Q 95.7 110.9 120.0 121.1 0> ^j -J C ^ Q) <—N w C ^ 1" 26.4 29.2 11.8 15.3 w ""? rt "^^^ *u ^ •H 'o oCO SP- SM sc sw SP GEOTECHNICAL DESCRIPTION Logged By SRH Sampled By SRH Red-brown, silty fine sand, loose, grass roots in upper 1 foot (possible fill) Gray clayey sand, slightly micaceous, wet, loose (possible fill ) ^ - Gray, fine to coarse sand with fine gravel, saturated, loose _ - Gray-white sandstone, wet, very dense - _ *Piezometer installed Total Depth: 25 Feet H90 @ 6 Feet LEIGHTON and ASSOCIATES FIGURE 4 [~1J - I SOIL TYPE OR LOCATION MAXIMUM DENSITY SOIL DESCRIPTION TEST RESULTS OPTIMUM MOISTURE(%) MAXIMUM DENSITY DRY (PCF) B-1 @ 5' Gray-brown clayey fine to medium 12.0 120 5 sand (SC) [ c Project NO, 480530-01 Leighton & Associates "GURE: 53IA (8/77) -. ' ' CZD •*"* O •z.O CD OunCO OI O g> CQ' IT O U e° V)Oo CDCO 100 90 80 70 2 60 5' 50n cr U.S. 2 1-1/2 Standard Sieves in inches 30 20 10 i 1 1 3/4 1/2 3/8 4 U.S.Standard 16 30 Numbers — 50 100 200 40 30 20 10 I ill i 1rl.11ILL 1141Lilt -L iL± jiiiiii li i_ il .ill' iii tm ilil: ttli tQi-ii^ 44:h IMM ..LU.-LLi. Jill 1 Uil HI ii all1U Hi i iiii mu B-l @ 5' I I I I i I M liilllililClayey fine n ito medium sand J l I X _1_!_ -U_ lllll JI! M.I JL I(sc I!intilii ^-rrtt .titiiM1041111 .... lili -H- -U-L .111.1- 00 90 80 70 60 20 10 50 10 1 0.5 Grain Size O.I 0.05 0.01 0.005 0.001 in Millimeters Gra vol Coarg*Fins Sand Coarto Modium Fin«Silt or Clay Symbol Hole No. Sample No. Depth or Elev. Field Moisture LL PI Activity Pl/-2u Cu Cc (D30)2 oionoeo Percent Passing No. 200 PercentPassing 2u U.S.C.S. RESULTS n '-* DIRECT SHEAR SUMMARY 1 j 330O D LJ 3OOO D — 2 3OO D in[;- to n '^ .300^ U :w n IOOO u • . 3OO n11 • • D - „ .p(\ ^\&~^ . p^O ^ &^>- wsx ^ ^^y\ = ^ .v^VVi^X / s-^^ /^ /L^ /"fii ^LfJ^ ^T^ _S jS ^T m,^<^ •xX"^i ' •^x'lx' s// ^//- X^X ^ 11 1^i\ / J / ^fh^ u^x- 36O 370 320 270 zeo 230 240 Z30 220 O 210 > 2OO 33190 m •«> 170 2 O 160 130 140 30 20 1 O 00 BO 80 7O 60 0 4O 3O 0 O u u (~~| ° 30° I00° 1300 2000 2SOO SOOO ^ NORMAL STRESS, PSF D FrictionB°nng Depth Symbol Angle Cohesion Remorks B-l 5' O 32° 50 psf Undisturbed H B-l 5' El 28° 250 psf Remolded to 90% n U Project No.1 l«0 A (8/77) 480530-01 Leighton & Associates FIGURE 7 CONSOLIDATION - PRESSURE CURVE inin4) Q. Ea ca>o <Q Oc/)zoo 0.05 0. PRESSURE (Kips per Square Foot) 0.5 1.0 5.0 10.0 50.0 0.05 O.I 0.5 1.0 5.0 10.0 50.0 Hi III' Iffm iiEEm. . t,~~,-Jjj, Jill I III ITT -ilil TT TIT 31 li II nnii Til t 1«-I iffil IT 11 iii 11 ¥ il ill ml mltiirlii .n fiiTl Ulil fTT 1 ! !a fflIMljtlllTIT "" J-l! m ilTmtl l UJJJi I J|i]J]|JlJUJJ!p iii iw.IDT ffl! nip^,m iff IL II 11jiji in; r^t r I!!HUM Ji! ntim n14IJlN ill iill " i Mliif n: 1! -Ul If f TT II Ml: liillira 111 Rill r-- —LProject No.: 3SU (12/77) O Indicates Sample At Reid Moisture Indicates Sample After Saturation 480530-01 Leighton & Associates FIGURE 8