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HomeMy WebLinkAbout3303; Agua Hedionda Sewage Pump Station; Squires Reservoir-Upper Chlorination Building; 1989-07-31Geotechnical Consultants PRELIMINARY GEOTECHNICAL INVESTIGATION, PROPOSED UPPER CHLORINATION BUILDING, SQUIRES RESERVOIR, COSTA REAL MUNICIPAL WATER DISTRICT, CARLSBAD, CALIFORNIA PREPARED FOR: LUKE-DUDEK CIVIL ENGINEERS, INC. 605 THIRD STREET ENCINITAS, CALIFORNIA 92024 JULY 31,1989 PROJECT NO. 100743-06 °)lii g © H 1 W B JUN30I992 1 CARLSBAD MUNICIPAL WATER DISTRICT Luke-Dudek Civil Engineers, Inc. July 31,1989 Project No. 100743-06 TABLE OF CONTENTS Page Scope of Services 1 Site Description 2 Proposed Development 2 Subsurface Investigation and Laboratory Testing 3 Geology and Subsurface Conditions 3 Seismicity 4 Conclusions and Recommendations 4 Illustrations Figure 1 - Boring Location Map Table 1 - Seismic Parameters for Active Faults Appendices Appendix A - References Appendix B - Boring Logs ?"^r '- ^v--^/**/' . ...j; . AI' . .• fz. ,r.S'; /-'J^f..,: Geotechnical Consultants July 31,1989 Project No. 100743-06 Luke-Dudek Civil Engineers, Inc. 605 Third Street Encinitas, California 92024 Attention: Mr. Steve Deering Subject: Preliminary Geotechnical Investigation Proposed Upper Chlorination Building, Squires Reservoir, Costa Real Municipal Water District, Carlsbad, California Gentlemen: In accordance with your request, we have performed a preliminary geotechnical investiga- tion at the site of the proposed facilities expansion for Squires Reservoir in Carlsbad, Cali- fornia. The purpose of the investigation was to evaluate the geotechnical conditions at the site with respect to the proposed construction of the upper chlorination building. This re- port presents our findings, conclusions and recommendations regarding the upper chlorina- tion building only. Scope of Services The scope of our services for this study included the following: o Review of previous geotechnical reports, project drawings and other materi- als as referenced in Appendix A. o Site visit and geologic reconnaissance. o Drilling of two small-diameter borings at the location of the proposed upper chlorination building. The borings were logged by a geologist from our office and soil samples were collected. o Laboratory testing of selected soil samples. Soil Engineering • Geology • Groundwater 10225 Barnes Canyon Road • Suite A-112 • San Diego, CA 92121 • (619) 457-0400 • Fax (619) 558-1236 Luke-Dudek Civil Engineers, Inc. July 31, 1989 Project No. 100743-06 o Geotechnical data analysis and engineering design for the proposed construc- tion. o Preparation of this report presenting our findings, conclusions and recom- mendations. Site Description The subject site is located in a generally undeveloped area just north of Squires Reservoir and slightly west of an existing hydroelectric station. There is relief of approximately 4 feet across the site, with elevations decreasing from south to north. Some grading has taken place for a proposed water storage tank to the northwest. Access roads leading to the site are generally dirt and unimproved. Proposed Development We understand that the proposed development will consist of a one-story, L-shaped chlori- nation building and attached scrubber pad. The scrubber pad is located within the "L" of the building, giving the entire structure dimensions of approximately 35 feet by 35 feet (1225 square feet). Based on our review of the available preliminary plans (Appendix A, Reference 2), the chlorination building is to be constructed with masonry walls and founded on continuous perimeter concrete footings with a concrete slab on grade. It is our understanding that the scrubber pad will consist of a slab on grade at the same elevation as the finished floor of the chlorination building. Building loads for the structure were not available at the time of this report. Minor grading is proposed at the building site. Site elevations are expected to change minimally as a result of the proposed grading. Based on review of the available plans it appears that it is intended to cut approximately two feet and place an equal amount of fill to create a level building pad for the structure. Luke-Dudek Civil Engineers, Inc. July 31, 1989 Project No. 100743-06 Subsurface Investigation and Laboratory Testing On July 14, 1989, representatives of our firm drilled two exploratory borings to a depth of 25 feet below the existing grade within the footprint of the proposed structure. The pur- pose of the borings was to observe the geotechnical conditions at the site, to log soil types, and to obtain soil samples. Bulk and Standard Penetration Test samples were obtained from both borings. The approximate locations of the borings are shown on Figure 1. Laboratory tests were performed on representative soil samples to evaluate moisture con- tent. The results of the tests are presented on the boring logs in Appendix B. Geology and Subsurface Conditions Based on our subsurface investigation, site reconnaissance and review of background in- formation, the site appears to be underlain by fill and decomposed granitic bedrock. De- tailed information regarding materials encountered is included in the boring logs in Ap- pendix B. A generalized description of these materials is presented below. Fill Soils The fill soils encountered in our borings consisted of medium to dark brown, damp, medium dense, silty fine sand and reworked decomposed granitics. The maximum depth of fill observed in the borings was approximately two feet. Decomposed Granitics The decomposed granitics encountered in our borings generally consisted of medium to light brown, damp, very dense, silty fine to very coarse-grained sand. Both borings were drilled to a depth of 25 feet without encountering refusal. Luke-Dudek Civil Engineers, Inc. July 31, 1989 Project No. 100743-06 Ground Water Ground water was not encountered in the test borings at the time of our field investigation. No seeps, springs or other indications of a shallow ground water table were observed at the site. Seismicity No active faults are known to occur on or adjacent to the site. The most significant seismic hazard at the site is ground shaking following an event on a distant active fault. Table 1 lists the major active regional faults, their distance from the site, anticipated peak bedrock acceleration, and repeatable high ground accelerations for the maximum probable earth- quake on each of these faults. The seismic event most likely to significantly affect the site would be the maximum proba- ble event on the Elsinore fault, which could produce a peak bedrock acceleration of 0.19g and repeatable high ground acceleration of 0.12g. An event on the potentially active Rose Canyon fault zone could produce a higher peak bedrock acceleration, but this is considered less likely than an event on the active Elsinore fault. Peak accelerations are not, however, generally used for design of structures. The project seismic design should be completed in accordance with regulations of the governing jurisdictions and standard practices of the Structural Engineers Association of California. Due to the dense nature of the bedrock at the site, seismically induced liquefaction, dy- namic settlement or landsliding within the native materials is deemed unlikely. Due to the distance between the site and the closest known active fault, seismically induced ground rupture or cracking is also deemed unlikely. CONCLUSIONS AND RECOMMENDATIONS Based on our field and laboratory test results, and the results of our analysis, it is our opinion that the proposed construction is feasible from a geotechnical standpoint provided the following recommendations are incorporated into the design, and sound construction Luke-Dudek Civil Engineers, Inc. July 31, 1989 Project No. 100743-06 practices are utilized. Recommendations for the site earthwork and construction of the upper chlorination building are provided below. Earthwork It is our understanding that minor grading will be performed at the site. Prior to commencement of grading, the site should be cleared of any debris, vegetation or other deleterious materials. Materials not suitable for structural backfill should be disposed of off-site. Existing fill soils should be removed and recompacted under and extending five feet laterally from the perimeter of all structures. Prior to placement of fill, the prepared subgrade should be scarified and moisture conditioned. We anticipate that placement and compaction of fill soils will be necessary to create the building pad. The on-site soils are generally suitable for use as compacted fill. Fill soils should be free of organic material or debris. Any imported fill soils, if required, should be nonexpansive granular soil approved by the geotechnical consultant prior to being brought on site. Fill soils should be moisture conditioned to slightly above optimum moisture content and compacted to a minimum of 90 percent relative compaction based on ASTM D1557-78. The lift thickness will be dependent upon the type of compaction equipment used, but generally fill should be placed in uniform lifts, not exceeding 8 inches in loose thickness. It is our understanding that the current plan calls for a transition (cut/fill) line through the building pad. Transition pads are not recommended. If the final grading plan indicates that a transition line will occur, the entire building pad should be undercut 3 feet and brought back up to finish grade with properly compacted, nonexpansive fill soils. Alternately, a change in design may be considered such that the entire finished pad is un- derlain by natural materials. Luke-Dudek Civil Engineers, Inc. July 31, 1989 Project No. 100743-06 Footings Continuous perimeter footings for the proposed chlorination building should be a minimum of 18 inches wide and be embedded at least 18 inches below the lowest adjacent grade. These footings should be reinforced with at least two No. 4 reinforcing bars top and two bottom. At this depth, concrete footings placed on firm decomposed granitics may be designed using an allowable bearing capacity of 4,000 pounds per square foot. At this depth, concrete footings placed on compacted fill may be designed using an allowable bearing capacity of 2,500 pounds per square foot. The allowable bearing capacity may be increased by 1/3 when considering loading of short duration such as wind or seismic forces. Total and differential settlement of footings designed in accordance with the above recommendations should be within normally tolerable limits. Foundations placed in decomposed granitic rock or properly compacted fill may be designed using a coefficient of friction of 0.35 (total frictional resistance equals coefficient of friction times the dead load). A designed passive resistance value of 300 pounds per square foot of depth (with a maximum value of 3000 pounds per square foot) may be used. The allowable lateral resistance may be taken as the sum of the frictional resistance and the passive resistance, provided the passive resistance does not exceed two-thirds of the total allowable resistance. Floor Slabs Floor slabs for the upper chlorination building should have a minimum thickness of 6 inches and be reinforced, at a minimum, with No. 4 reinforcing bars on 18 inch centers each way. We recommend the use of "chairs" to properly locate the reinforcement in the middle 1/3 of the slab. If moisture sensitive equipment or floor coverings are to be installed, the floor slabs should be underlain by a 6-mil Visqueen moisture barrier covered with at least 2 inches of clean washed sand and underlain by 4 inches of 3/8 inch gravel. The sand directly underlying the slab should be moistened prior to concrete placement. Slabs should have crack control joints with appropriate spacings as recommended by the structural engineer. Luke-Dudek Civil Engineers, Inc. July 31,1989 Project No. 100743-06 Concrete Construction Concrete should be placed with a maximum slump of 4 inches under the observation and testing of a qualified materials testing laboratory. We recommend that a slump test be conducted for each concrete truck. Potential for slab shrinkage and associated cracking may be reduced by the addition of fiber mesh in the concrete and by careful control of water/cement ratios during concrete placement. Site Drainage Positive site drainage should be established and maintained around the proposed structures at the subject site. Positive drainage may be established by providing a ground surface gradient away from structures of at least 2 percent for a distance of 5 feet outside the perimeter of the structures. Accumulated surface runoff should be directed off-site by providing a graded swale with a gradient of at least one percent to an appropriate surface collector and/or tightlined to a suitable outlet. Roof drainage control measures should include rain collection systems such as gutters and downspouts. Construction Observation and Limitations Geotechnical services outlined in this report have been performed in accordance with current practice and the standard of care exercised by a geotechnical consultant performing similar tasks in this area. No other warranty, expressed or implied, is made regarding the conclusions, recommendations and professional opinions presented in this report. Site conditions may vary from those observed in this report. Our conclusions and recommenda- tions are based on an analysis of the observed conditions. If actual conditions differ from those described in this report, our office should be notified and additional recommendations, if required, can be provided upon request. Luke-Dudek Civil Engineers, Inc.July 31,1989 Project No. 100743-06 We appreciate the opportunity to be of service. Should you have any questions regarding this project please feel free to contact this office. Very truly yours, NINYO & MOORE Thomas C Gray, CEG 281 Chief Geologist GJS/LPR/TCG/CAC/cs Distribution: (4) Addressee Clifford A, Craft, RCE 28832/GE243 Chief Geotechnical Engineer 8 Existing 42" Water Line Existing 21' Water Line \\\ Existing Hydro-Electric Station Proposed Chlorine Building \ \ Existing Sewage Holding Tanks Existing Reservoir Keeper's House Existing KKOS Radio Towe B-2 LEGEND Approximate location of exploratory boring Indicates proposed slope Proposed asphaltic concrete paving 4O 80 Approximate Scale in Feet NOTE: PLOT PLAN PREPARED DURING ON-SITE RECONNAISSANCE AND SHOULD NOT BE CONSIDERED A RECORD OF SURVEY. ALL DIMENSIONS ARE APPROXIMATE. DRAWING ADAPTED FROM LUKE-DUDEK CIVIL ENGINEERS, INC., SITE PLAN, PRELIMINARY DRAWINGS FOR COSTA REAL MUNICIPAL WATER DISTRICT, DATED 6/27/89. BORING LOCATION MAP UPPER CHLORINE BUILDING COSTA REAL WATER DISTRICT PROJECT NO. 100743-06 DATE 7/89 FIGURE 1 Luke-Dudek Civil Engineers, Inc.July 24, 1989 Project No. 100743-06 TABLE 1 SEISMIC PARAMETERS FOR ACTIVE FAULTS Fault San Andreas San Jacinto Coronado Banks Elsinore *Rose Canyon Approximate Distance From Fault To Site (Miles) 73 45 21 19 6 Maximum Probable Earthquake Peak Bedrock (Richter Acceleration Magnitude1) (Gravity) 7.2 7.2 6.0 6.7 6.0 <0.05 0.08 0.11 0.19 0.35 This fault is considered "potentially active". Repeatable High Ground Acceleration (Gravity)** <0.05 0.08 0.11 0.12 0.23 The repeatable high ground acceleration may be taken as 65% of the peak acceleration for sites within 20 miles of the epicenter (after Ploessel and Slosson, 1974). , : /,'/,' ** * ,x/ -' ~s>v ' * * * ^ ? \:',-x;-."J '$', "*', ;.-^ '. l ,,-*'- " '< 'KA'-j^. ;." ' *'.'. " »V -s , • ^, i:", ^/-,.,.., /-; •''."'' ..,..'-: - Vl^*^^-'''''' T^*^ ;,i:'V ' -• -v- / """.-:C- .'>' \ '..-••- '•'•::'•* -• --: «-:- ;:^-.^ir n, -^,*%v, >.' .• f~^ ^ V-;:;:^ir i-,;t •' - - * ;«,n^"|^^: •''- •; ?-1^^^ ,A Luke-Dudek Civil Engineers, Inc. July 24, 1989 Project No. 100743-06 APPENDIX A References 1. Luke-Dudek, 1988, Proposal for Facilities Upgrade and Expansion for Squires Reservoir, Costa Real Municipal Water District, Project No. 87-109, February. 2. Luke-Dudek, 1989, 50% Submittal Plans, dated July 17. 3. Ninyo & Moore, 1988, Preliminary Geotechnical Investigation, Facilities Expansion for Squires Reservoir, Costa Real Municipal Water District, Carlsbad, California, dated September 9. 4. Ploessel, M.R. and Slosson, J.E., 1974, Repeatable High Ground Accelerations from Earthquakes, Earthquake Engineering Research Institute, Monograph Series. 5. Weber, F. Harold, 1982, Geologic Map of North-Central Coastal Area of San Diego County, California, Showing Recent Slope Failures and Predevelopment Landslides. Aerial Photographs Source Date Scale Flight Numbers USD A 4-11-53 1:20,000 AXN-8M 22 and 23 APPENDIX B r I'tfV - ; ** ' ", *• • ^ „j ,ji-''^ ^ '' >\" MAJOR DIVISIONS « _ —do*0 S-S COARSE GRAINED S(More than 1 '2 of> No. 200 sieve s3sl5 — <•5, o „ o? 5£ r- » < §§gsS gS« JE 5 V GRAVELS (More than 1-2 of coarse fraction ^*No. 4 sieve size) SANDS (More than 1'2 of coarse fraction <. No. 4 sieve size) SILTS & CLAYS Liquid Limit *=:50 SILTS & CLAYS Liquid Limit > 50 HIGHLY ORGANIC SOILS SYMBOL GW GP GM GC SW SP SM SC ML CL OL MH CH OH Pt TYPICAL NAMES Well graded gravels or gravel-sand mixtures, little or no fines Poorly graded gravels or gravel-sand mixtures, little or no fines Silty gravels, gravel-sand-silt mixtures Clayey gravels, gravel-sand-clay mixtures Well graded sands or gravelly sands, little or no fines Poorly graded sands or gravelly sands, little or no fines Silty sands, sand-silt mixtures Clayey sands, sand-clay mixtures Inorganic silts and very fine sands, rock flour, silty or clayey fine sands or clayey silts with slight plasticity Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays Organic silts and organic silty clays of low plasticity Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts Inorganic clays of high plasticity, fat clays Organic clays of medium to high plasticity, organic silty clays, organic silts Peat and other highly organic soils CLASSIFICATION CHART (Unified Soil Classification System) CLASSIFICATION BOULDERS COBBLES GRAVEL Coarse Fine SAND Coarse Medium Fine SILT & CLAY RANGE OF GRAIN SIZES U.S. StandardSieve Size Above 12* 12" to 3" 3" to No. 4 3" to 3/4" 3 '4" to No. 4 No. 4 to No. 200 No. 4 to No. 10 No. 10 to No. 40 No. 40 to No. 200 Below No. 200 Grain Size in Millimeters Above 305 305 to 76.2 76.2 to 4.76 76.2 to 19.1 19.1 to 4.76 4.76 to 0.074 4.76 to 2.00 2.00 to 0.420 0.420 to 0.074 Below 0.074 PLASTICITY INDEX (PI) %_ -* to w *> in a0 0 0 0 0 0 cs / / / CL-ML S~ /ML I/ / CL / ML / / & OL / / CH / MH& , ' OH GRAIN SIZE CHART 10 20 30 40 50 60 70 80 LIQUID LIMIT (LL), % PLASTICITY CHART U.S.C.S. METHOD OF SOIL CLASSIFICATION ^^ u.JE 0 - 5 - 10- «H 20- ••• i j « < Jg 3 , • H. ,A 51 f g e• O , - f I v« J| 1 Ou. (A 300 . ' \m*YA f Ul . aO 9^ i__«» tr £*«* £ u OCO bdU t> • ji ^jy\ DATE DRILLED BORINQ NO. GROUND ELEVATION SHEET OF METHOD OP DRILLING DRIVE WEIGHT DROP SAMPLED BY ' "««FP BY DESCRIPTION Undisturbed drive sample Bulk sample Seepage Ground water table Standard penetration test Solid line denotes formation change Dashed line denotes lithologic gradational change. BORING LOGoorel^^^* ^•••1 Explanation of Boring Log PROJECT NO. DATE RGURE c 4)U. I o. UJ0 (AHI 0. (A JCam 10-. • 15-taj 20 ' ••M c« h»O "- o0u. (f> O m Jiop • 10"n ,115• -":9" 100 • x^• E 6" b° HI OC ^. 5 3.7 2.3 3.1 IL S; > 2 HI0 ccQ - - Zg y 2 </> ^ o SM 1 DATE DRILLED 7/14/89 BORING NO. B-l GROUND ELEVATION 510'± (MSL) SHEET 1 OF 2 METHOD OF DRILLING 8" Hollow Stem Auger DRIVE WEIGHT 14° !t>s- DROP 30" SAMPLED BY MK/GJS LOOGFr> BY MK/GJS DESCRIPTION FILL; Medium dark brown, damp, medium dense, silty, firm SAND and decomposed granitic rock. DECOMPOSED GRANITIC ROCK: Medium brown, damp, dense to very dense, silty, medium to coarse SAND; decomposed granitic rock. Color changes to light brown to olive green, damp, very dense, medium to coarse, poorly graded, silty SAND; decomposed granitic rock. - A BORING LOG l^ffffIJU&f^f^^^yi£ %jr __ Upper Chlorine Building Y 9J F ••• Costa Real Water District PROJECT NO. DATE B_! 100743-06 8/79 RGURE v» u.DEPTHtn ja2 (0 JC 3 c 41 _> O 0u.*x BLOWS2°-WjfW 30- 35- 4n_ 7 S (A Os 4.5 S >• </> Ula >- o - zo N55 2w =>2y DATF nRii LED 7/14/89 BORING NO. B'1 GROUND ELEVATION 510' ± (MSL) SHEET 2 Of 2 MFTwon nP DRII i INR 8" Hollow Stem Auger DRIVE WEIGHT 140 Ibs. DROP 30" SAMPLED BY MK/GJS i orsnpr) BY MK/GJS DESCRIPTION Light brown to olive green, damp, very dense, silty, medium to coarse, poorly graded SAND; decomposed granitic rock. Total Depth 25' . No Ground Water. No caving. Backfilled 7/14/89. . _ BORING LOG _^_Xl^iCi^<C/<(L^*-Al^WB\ll~U^^ Upper Chlorine Building f «^ f Costa Real Water District PROJECT NO. DATE B_2100743-06 8/89 FIGURE B ^ CO zo DATE DRILLED 7/14/89 BORING NO. B-2 SHEET L_ OFGROUND ELEVATION 509'± (MSL) METHOD OF DRILLING 8" Hollow Stem Auger DRIVE WEIGHT 140 Ibs. DROP 30" SAMPLED BY ^S LOGGED BY MK DESCRIPTION SM FILL; Medium brown, dry, medium dense, silty fine SAND. DECOMPOSED GRANITIC ROCK; Orange-brown, damp, .medium dense, silty fine to medium SAND; decomposed granitic rock. 30 10.3 Light brown and light orange, damp, dense, poorly graded, silty fine SAND; decomposed granitic rock. 73 Light brown, damp, very dense, silty medium to coarse SAND; granitic rock, trace of clay. 15- 77 12.5 Light brown, damp, very dense, silty medium to coarse, poorly graded SAND; decomposed granitic rock. BORING LOG Upper Chlorine Building Costa Real Water District PROJECT NO. 100743-06 DATE 8/89 FIGURE B-3 X DEPTH (Feev>111 az « "3m c01>BLOWS/FOCo| 1 20— hMH^ ^•104 30- 35- 1 ' ~ 11" ?MOISTURE (5.2 a *Y DENSITYO - z0 :LASSIFICAIU.S.C.S.DATE DRILLED 7/14/89 BORING NO. B"2 GROUND ELEVATION 509 '± (MSL) METHOD OF DRILLIN DRIVE WEIGHT * SAMPLED BY R 8" Hollow 40 Ibs. Stem Auqer SHEET 2 OF 2 DROP 30" K i orsftFn RV MK DESCRIPTION Light brown, damp, very dense, silty medium to coarse, poorly graded SAND; decomposed granitic rock. Total Depth 25' . No Ground Water. No Caving. Backfilled 7/14/89. 1U _>V%-^/Woore_BORING LOG Upper Chlorine Building Costa Real Water District PROJECT NO. 100743-06 8/89 FIGURE B~4