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HomeMy WebLinkAbout3299; Home Plant Lift Station; Pump Station North of State St & Carlsbad Blvd; 1987-10-26I E I I E E I _ I I I I ADDENDUM TO PRELIMINARY GEOTECHNICAL EVALUATION PUMP STATION, CITY OF CARLSBAD NORTH OF THE INTERSECTION OF STATE STREET AND CARLSBAD BOULEVARD CARLSBAD, CALIFORNIA PREPARED FOR: MR. BILL KOPTIONAK ALMGREN & KOPTIONAK - 9968 HIBERT STREET, SUITE 102 I SAN DIEGO, CALIFORNIA 92131 OCTOBER 26, 1987 PROJECT NO. 100239-02 Almgren & Koptionak October 26, 1987 Project No. 100259-02 Table of Contents Site Description ...................................................................................................................... 1 Proposed Site Development ................................................................................................. 2 Field Exploration and Laboratory Testing ............. . ........................................................... 2 Subsurface Conditions ........................................................................................................... 2 Conclusions and Recommendations ................................................................................... 3 Illustrations Figure 1A - Site Location Map Figure 2A - Site Plan Figure 3A - Lateral and Uplift Pressure Diagrams Appendices Appendix A - References Appendix B - Boring Log - * A07027*Moore r W"^ r Geotechnii I I E E y I I I I I I I Geotechnical Consultants October 26,1987 Project No. 100239-02 Almgren & Koptionak 9968 Hibert Street, Suite 102 San Diego, California 92131 Attention: Mr. Bill Koptionak Subject: Addendum to "Preliminary Geotechnical Evaluation, Pump Station, City of Carlsbad, North of the Intersection of State Street and Carlsbad Boulevard, Carlsbad, California." Gentlemen: This addendum to our previously submitted report (Appendix A, Reference 1), presents the results of additional subsurface investigation performed at the revised location of the facility. The purpose of this study was to evaluate the site materials relative to the results, conclusions and recommendations presented in the referenced report, and to modify these, or present new recommendations for the design and construction of the planned facility. Site Description The subject property consists of a roughly triangular shaped lot just north of the inter- section of Carlsbad Boulevard and State Street in Carlsbad, California (Figure 1A). The site is relatively level at an approximate elevation of 31 feet (MSL) and has no significant vegetation. A 100 foot diameter trickling filter tank structure exists approximately 12 feet north of the northern boundary of the site, at approximately the same elevation. To the south, the site descends at a slope ratio of approximately 5:1 (horizontal to vertical) to a railroad right-of-way at approximate elevation 22 feet (MSL). To the east, a slope as- cends toward Carlsbad Boulevard at a slope ratio of approximately 5:1 (horizontal to verti- cal), to approximate elevation 37 feet (MSL). Soil Engineering • Geology • Groundwater 10225 Barnes Canyon Road • Suite A-l 12 • San Diego. CA 92121 • (619)457-0400 Almgren & Koptionak October 26,1987 Project No. 100239-02 Proposed Site Development ** The proposed site development will include construction of a partially underground sewage pump station. Based on preliminary plans and sections (Appendix A, Reference 2 and 3), *j the dry and wet well will be approximately 28 feet deep. A diesel generator room will be 4 located southeast of the wells founded at, or close to, the existing ground surface. We un- m derstand that only minor grading will be required, thus the site will remain at approxi- 4! mately the existing grade. mi^ Field Exploration and Laboratory Testing *| Subsurface conditions at this new location were evaluated by drilling one test boring (B- 1A) to a depth of approximately 35.5 feet below existing grade. A geologist was present «! during the drilling operation to log materials encountered and to obtain representative soil * samples. A boring log is presented in Appendix B, and the boring location is shown in Fig- m ure 2A. Sampling in the boring consisted of relatively undisturbed ring samples obtained H using a sampler driven into the soil with a 140 pound hammer, dropping 30 inches. The number of blows required for 12 inches of penetration is shown on the boring log. Laboratory tests were performed on representative soil samples obtained from the ex- ploratory boring to evaluate in-place moisture and density characteristics, and all samples were visually classified. The test results are presented on the boring log (Appendix B). * Subsurface Conditions «• Based on our subsurface investigation and review of the map by W,eber, 1982, the geologic formation present at the site is the Eocene Santiago Formation. About 11 feet of beach g, deposits, followed by approximately 5 feet of man-made fill overlie the Santiago Forma- tion. Groundwater was encountered at a depth of about 30 feet in the boring. Detail descriptions of the materials encountered are presented on the boring log (Appendix B). Generalized descriptions of the materials encountered are as follows: Almgren & Koptionak October 26,1987 Project No. 100239-02 gg o Fill j The fill material generally consisted of brown firm silty sandy clay, and clayey silt, with some gravel. mill o Beach Deposits •m <l These deposits consisted of generally gray-green, dense, silty fine sand with m zones of brown-orange oxide stains, and occasional coarse sand pockets. g o Santiago Formation1 m The Santiago Formation as observed, consisted of weakly cemented in- m terbedded very dense sandy siltstone and silty sandstone, with minor amounts ^^*of clay and occasional coarse sand or fine gravel. - CONCLUSIONS AND RECOMMENDATIONS M Conclusions The results of this additional investigation indicate that the subsurface conditions are sim- ilar to those reported in our earlier report (Appendix A, Reference 1). Considering the ** geotechnical aspects of design and construction, the conditions at this proposed location appear generally more favorable, than those of the prior site. Because the revised location ^ is at a higher elevation than the previous site, the depth to groundwater is greater. After *' evaluating the soil moisture data from this subsurface investigation in relation to the data q, from the original site, and the general topography, adaptation of a design groundwater If level of 20 feet (MSL) is, in our opinion, appropriate. The depth of undocumented man- made fill appears less than 5 feet, and the fill is underlain by the beach deposits, which are ^WJ j competent bearing materials. The formational material is very dense, with varying degrees of cementation, and is predominantly granular. Almgren & Koptionak October 26,1987 Project No. 100239-02 g| Excavation can, in our opinion, be accomplished with normal mechanical excavating equipment. However, depending on the size and power of the equipment, loosening of the 2 formational material may occasionally be required, and can, in our opinion, be accom- plished by utilizing a mechanical "bull point" or rock breaker. m ^j In general, we conclude that the recommendations presented in our earlier report for this «t project (Appendix A, Reference 1) are valid, other than as modified below: * m Recommendations jg These recommendations are based on current site conditions and our understanding of the ^ proposed construction. If the site is modified by grading or the location of the proposed fa- cility is changed, our office should be contacted to review these changes and provide addi- m tional recommendations as appropriate. It should also be noted that the recommendations j^u presented herein are in addition to, or modify the recommendations presented in our ear- «• Her report for this project (Appendix A, Reference 1), and should therefore be read only in *• conjunction with the earlier report. m Earthwork o Fill Materialsa, "" The onsite formational materials and beach deposits are generally suitable for use as compacted fill, provided they are free of debris. " The existing fill materials, due to their apparent significant clay con- * tent, are considered reusable only as backfill and in the uppermost 2 ni foot zone, to provide a semi-impermeable barrier for surface water «t migration into the deeper backfill. •I Almgren & Koptionak October 26,1987 Project No. 100239-02 ^ Foundations j Unless a perimeter subdrain is installed at a lower elevation, and directed offsite, a groundwater elevation of +20 feet (MSL) should be considered for * design. 4 m o Wet and Dry Well Foundation Mat and Walls m We recommend that the foundation mat and walls be designed for the ^^^g uplift and lateral pressures shown on Figure 3A, "Lateral and Uplift Pressure Diagrams." Ml o Generator Foundation IB* m The loads of the generator structure may be transferred to the under- ""• lying dense beach deposits, rather than to the formational materials, *•» as recommended in our previous report. This can be accomplished by „,, removing the undocumented fill to the top of the beach deposits, re- ^ placing it with structural fill and using conventional footings and slab- on-grade (Option A in earlier report), or by deepening the footings to bear 1 foot minimum into the beach deposits and using a structural slab (Option C in the earlier report). Supporting the building frame *" on drilled piers (Option B of the earlier report) is not considered eco- m nomically viable due to the relative shallowness of the fill. Detailed m recommendations on Options A and C are presented in the earlier ^ report. . - „ "fHi Drainage m^ Should significant economies result from lowering the design groundwater level, a perimeter subdrain at a lower elevation can be installed. Modified m- design pressure diagrams can be prepared to reflect the modified subdrain Almgren & Koptionak October 26,1987 Project No. 100239-02 gl elevation. General recommendations for design of underground drainage are presented in the earlier report. H Construction Considerations mgj o Shoring m *• Due to the close proximity of the adjacent trickling filter structure, it «, is recommended that the portion of well excavation below 15 feet (i.e., m in the formation) not be laid back, but be shored. The proximity of other settlement sensitive underground structures may otherwise guide selection of shoring or laying back of excavation slopes. Laid back slopes should in all cases be at slope ratios no steeper than 1:1 (horizontal to vertical).m "* o Special Precautions — The close proximity of the power line guywire anchors to the west of m the site should be considered prior to planning the excavation. «*• Construction Observation «• *• The recommendations provided in this report are based on conditions disclosed by our sub- m surface investigation. The interpolated subsurface conditions should be checked in the « field during construction. We recommend that final project drawings be reviewed by our office prior to construction. We recommend that all footing excavations be observed by a representative of our firm, and that testing and observation of fill placement be performed by a representative of this firm to evaluate compliance with recommendations provided in this and the earlier report. Almgren & Koptionak October 26,1987 Project No. 100239-02 The field investigation, laboratory testing and geotechnical analysis presented in this report have been conducted in accordance with current engineering practice. Our observations are based on one test boring located on the site and our recommendations reflect the con- ditions encountered therein. Variations may exist, and conditions not observed nor de- scribed in this report may be encountered during construction. If conditions different from those described in this report are encountered, this office should be notified and additional recommendations, if applicable, should be requested. We appreciate this opportunity to be of service, and if you should have any questions re- garding this matter please contact this office. Very truly yours, NINYO & MOORE Jan A. Dahlgren Associate Steph Principal Geologist £oy E. Moore, Principal JAD/SWJ/REM/eg Distribution: (2) Address^ REFERENCE: 1986 Aerial Foto-Map Book. 2000 Scale In Feet 4000 NORTH SITE LOCATION MAP CITY OF CARLSBAD PUMP STATION FACILITY CARLSBAD, CALIFORNIA PROJECT NO. 100239-02 DATE 10/87 FIGURE 1 A TRICKLING FILTER.0 B-1A LEGEND Approximate location of exploratory boring BASE MAP IS AN UNTITLED, UNDATED SKETCH, FURNISHED BY ALMGREN & KOPTIONAK. ALL DIMENSIONS ARE APPROXIMATE. NORTH 20 Approximate Scale in Feet 40 SITE PLAN CITY OF CARLSBAD PUMP STATION FACILITY CARLSBAD, CALIFORNIA PROJECT NO 100239-02 DATE 10/87 FIGURE 2A Finish grade Elevation +20 MSL V Bottom of Mat Elevation 60.Yi.Y. PSF L- 62.4x X PSF X 91.2x X PSF X ASSUMED CONDITIONS 1. At rest conditions Ko equals 0.5 2. VSoil (moist) equals 120 PCF NOT TO SCALE LATERAL AND UPLIFT PRESSURE DIAGRAMS CITY OF CARLSBAD PUMP STATION FACILITY CARLSBAD, CALIFORNIA PROJECT NO 100239-02 DATE 10/87 FIGURE 3 A Almgren & Koptionak October 26,1987 Project No. 100259-02 APPENDIX A References 1. Ninyo & Moore, 1987, "Preliminary Geotechnical Evaluation, Pump Station, City of Carlsbad, North of Intersection of State Street and Carlsbad Boulevard, Carlsbad, California," dated April 30. 2. Untitled, undated site topography and sketches of facility location, furnished by Almgren & Koptionak. 3. Almgren & Koptionak, Inc, untitled, undated, schematic drawing of facility plan and sections. APPENDIX B MAJOR DIVISIONS COARSE GRAINED SOILS(Mora than 1/2 ol soil > no. 200 (lev* size)FINE GRAINED SOILS 1(More than 1/2 ol »oM < no. 20O «l«ve «li«) IGRAVEL3 (More thin 1/2 of coin* friction > no. 4 ileve lilt) SANDS (Mor* thin 1/2 of coarie friction <^ no. 4 sieve tlze) SILTS & CLAYS LL < 50 SILTS & CLAYS LL > 50 HIGHLY ORGANIC SOILS SYMBOLS GW GP GM GC SW SP SM SC ML CL OL MH CH OH Pt TYPICAL NAMES We* grided gravele or oravel-iand mtxturee» into or no fV>e« Poorly gridid gnvel* or grivet-tand mixture*, little or no tlnti Silly gravel*, gravel-iand-illt mixture* Cliyey gnvel*. gnvel-iand-clay mixture* Wtll grided tindt or grivilly lande. little or' no tine* Poorly grided tindi or gravelly tind*. little or no fine* Sllty undi, iind-illt mixture* Clayey iind*, und-cliy mixture* Inorginlc (lltl ind very line iind*. rock flour. »llty or cliyey line land* or cliyey illti wKh iKght plittlcKy Inorganic cliy* of low to medium pUetlclty, gravelly cliyt. undy cliye, illty clay*, lein cliy* Orgi^lc tilt* end orginlo f Uty ctiy* of low pUitlcrty Inorginlc lilt*, mlcieeou* or dlitomiceou* (In* tindy or illty loll*, elutlo tilt* Inorganlo cliye ol high plutlclty, lit cliy* Orgink: city* of medium to high plittfclty, organic illty cliyi, orginlo lilt* Peat and other highly organic loll* CLASSIFICATION CHART (Unified Soil Classification System) CLASSIFICATION BOULDERS COBBLES GRAVEL coirie line SAND coirie medium line SILT 4 CLAY RANGE OF GRAIN SIZES U.S. Standard Sieve Size Above 12" 12" to 3" 3" to No. 4 »" to J/4" »/4" to No. 4 No. 4 to No. 200 No. 4 la No. 10 M«. 10 to Hi. 40 No. 40 10 N«.JOO Below No. 200 Grain. Size In Millimeter* Above 305 308 to 70.2 70.2 to 4.76 re. a to i*.t ii.i t* 4.re 4.76 to 0.074 4.re 10 2.00 2.00 10 0.420 0.420 to 0.074 Below 0.074 30 5* 7 40 ^c X, I 3° o a - 20 a. 10 y - x - / y/^/^CL-ML^ / 1 ML 1 / x CL x ^^ / ML a OL 1 x X CH X MH a X x OH GRAIN SIZE CHART 10 20 SO 40 SO 60 LL (Ll,uU Limit), % PLASTICITY CHART 70 80 U.S.C.S. METHOD OF SOIL CLASSIFICATION «0LL JE ui Q — - 5 - 15- 20 ••• ci 0• <c jj"3 - • ' rA 9I . F5 c•> Q 1 | M 1 0u. (/) 5o 00 1 *1V ? HIcc3 wo ?^* JL- "U--«» o0. >- (/) 2 CC O (QO)- Y/A zo o(1M(O = 3Q ,M ^yyi DATE DRILLED BORING NO- GROUND ELEVATION SHEET OF METHOD OF DRILLING DRIVE WEIGHT DROP SAMPLED BY ' OfiGED BY DESCRIPTION — Undistxurbsd clirivG ssinpl© Standard penetration test - - BORING LOGtoorel^^^ BBBi Explanation of Boring Log PROJECT NO. DATE F|QURE 4 "Sd>«u. UJQ 5- 10- 15- 20- •• ci < 4 C 13 CD : 1 L ,4 nuj \ 8 c•_>^ Q 1 ' |I 1 m 1 ou. w _Jm 29 42 49 _ ]QO+ I JU<|0 * 23 S0 mm mm^mm L3.4 L2.5 5.6 7.0 3.4 3.0 •• mmmmm 11.9 11.7 "L..«» IT*uQ.••^>• CO U) >•(3C Q 106.3 105.5 104.6 110.1 111.2 109.0 117.9 ro& o SSy< o |sc ML/CL SM SM SM-ML 41 Myyi DATE DRILLED 10/19/87 BORING NO. B-1A GROUND ELEVATION 31<- (MSL) SHEET I OF 2 METHOD OF DRILLING 6" Diar^eter Hollow Stem Auger (2) DRIVE WEIGHT 140 Ibs . DROp 30" SAMPLED BY RAR ' ORriED BY BAB DESCRIPTION FILL: Brown, damp, firm, sandy CLAY with gravels. Brown to dark brown, damp, firm, clayey SILT and brown, dry, silty CLAY; some sand. BEACH DEPOSITS: Mottled gray-green to gray-brown, damp, dense, slightly silty, fine-grained SAND; occasional zones with orange iron oxides. Becomes brown-orange, increase in oxides at 6.5 feet. Becomes gray-green with occasional layers of coarse-grained sand and zones of black minerals at 10.0 feet. Siltier, trace to some clay. SANTIAGO FORMATION: Interbedded, green-gray, damp to moist, silty, coarse-grained SANDSTONE and coarse-grained, sandy SILTSTONE; weakly cemented. - CONTINUED - BORING LOG A0%^ W %5 __ Carlsbad Pump Station City of Carlsbad, California PROJECT NO. DATE 100239-02 10/87 FIGURE B L m m 4)4)U. X tila ^o— 25- 30- 35- 40 •Bl tli c3<(/ 1 "5m -' - _ - ,A — i)ij L; C c 0^> a -' 1! j I M 1 OLL CO _lca 1004 1004 1 W.V1 5 111cc3 10os in c: 18.2 12.0 11.4 "4 Oa. >tCOzHI > a 1 1 Q T 123.5 r0& zo o,1&«*W =< y A M/yi DATE DRILLED 10/19/87 BORING NO. B~1A GROUND ELEVATION 31'~ (MSL) SHEET 2 OF 2 METHOD OF nmLi IMP, 6" Diameter Hollow Stem Auger (2) DRIVE WEIGHT 14° lbs' DROP 3°" SAMPLED BY 'BKB 1 O^GED BY BAB DESCRIPTION SANTIAGO FORMATION: Interbedded, green-gray, damp to moist, silty, coarse-grained SANDSTONE and coarse-grained, sandy SILTSTONE; weakly cemented Total Depth = 35.5 feet.•*• • * Apparent ground water @ approximately 30.0 feet. (1) Backfilled 10/19/87. NOTES : ,1. Added water to hole at approximately 15.0 feet. 2. Changed from hollow stem auger to solid stem auger BORING LOG i\J%JJ^^5^^^ Carlsbad Pump Station City of Carlsbad, California PROJECT NO. DATE 100239-02 10/87 FIGURE B 2