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HomeMy WebLinkAbout; SDG&E Encina Wastewater Facility; Soils Report; 1988-07-18wmdward.clydeconsultants Project No. 87512373~SIOl GEOTECHNICAL INVESTIGATION FOR THE PROPOSED SDG&E ENCINA POWER PLANT NEW WASTEWATER FACILITY CARLSBAD, CALIFORNIA Prepared for: San Diego Gas & Electric Company 101 Ash Street P.O. Box 1831 San Diego, California 1550 Hotel Circle North San Diego. California 92108 619-294-9400 Fax: (619) 293-7920 July 18, 1988 Project No. 87512373SIOl San Diego Gas & Electric Company 101 Ash Street P.O. Box 1831 San Diego, California 92112 Attention: Ms. Chris Rychel GEOTECHNICAL INVESTIGATION FOR THE PROPOSED SDG&E ENCINA POWER PLANT NEW WASTEWATER FACILITY CARLSBAD, CALIFORNIA Gentlemen: Woodward=Clyde Consultants ENG\NEER\NG DEPT. L16RARY city ot Callsbad . 2075 IJS Palmas me c&bad, CA 92009-485g Woodward-Clyde Consultants is pleased to provide the accompanying report, which presents the results of our geotechnical investigation for the project. This study was performed in accordance with your authorization of April 25, 1988 and our agreement dated May 9, 1988. This report presents our conclusions and recommendations pertaining to the project, as well as the results of our field explorations and laboratory tests. If you have any questions or if we can be of further service, please give us a call. Very truly yours, WOODWARD-CLYDE CONSlJLTANTS Consulting Engineers. Geologists and Environmental Scientists Otfices in Other Principal Cities Project No. 87512373SIOl TABLE OF CONTENTS PURPOSE AND SCOPE OF INVESTIGATON PAGE NO, 1 DESCRIPTION OF THE PROIECI 2 BACKGROUND INFORMATION 2 FIELD AND LABORATORY INVESTIGATIONS 3 SlTE CONDlTIONS 3 Geologic Setting Site Conditions Subsurface Conditions Groundwater : 4 6 DISCUSSIONS, CONCLUSIONS, AND RECOMMENDATIONS 6 Potential Geologic Hazards Soil Characteristics and Groundwater Conditions Omiing Slopes Drainage Foundations Soil Bearing Capacity Estimated Settlements Retaining Walls Resistance to Lateral Loads Pavement 6 7 ! ; 10 :: ::. UNCERTAINTY AND LIMITATIONS 12 1. Estimated Active Lateral Earth Pressure for Retaining Walls in Terms of Equivalent Fluid Pressure 1. Site Plan Aunendices Field Investigation Laboratory Tests Guide Specifications for Earthwork Guide Specifications for Wall Drains a/vbl i Project No. 87512373-SIOl GEGTECI-INICAL INVESTIGATION FOR THE PROPOSED XXI&E ENCINA POWER PLANT NEW WASTEWATER FACILITY CARLSBAD, CALIFORNIA PURPOSE AND SCOPE OF INVESTIGATION This report presents the results of our geotechnical investigation at the site of the proposed SDG&E Encina Power Plant new wastewater facility. The site is located immediately northeast of Ponds #3 and#M of the existing primary wastewater facility and southeast of Agua Hedionda Lagoon. This report has been prepared exclusively for SDG&E and their consultants for use in evaluating the property and in project design. This report presents our conclusions and/or recommendations regarding: General subsurface soil conditions; General extent of existing fii soils; Conditions of areas to receive fill, Characteristics of proposed fill material, Presence and effect of expansive soils; Grouudwater conditions within the depths of our subsurface investigation; Grading and earthwork; Types and depths of foundations; Allowable soil bearing pressures; Allowable soil friction resistance; Vertical coefficient of subgrade reaction; Settlements; Design pressures for retaining walls; and Pavement design. Additionally, we are providing recommendations regarding stability of slopes, as well as a discussion on potential geologic hazards and soil liquefaction potential. The above a/vbl -l- Project No. 87512373-SIOl discussion is predominantly based on the results of our earlier work for the Encina Power Plant site. DESCRIPTION OF THE PROJECT For our study, we have discussed the project with Ms. Chris Rychel of SDG&E. We have also been provided with a copy of a drawing entitled “Wastewater Ponds Replacement Project”, dated May 9, 1988 and with four sketched cross sections, dated July 1, 1988, all prepared by SDG&E. We understand that the proposed project will include construction of four aboveground wastewater tanks, of up to 45 feet in diameter and 30 feet in height; construction of low volume and sludge tanks, coalescers, and other appurtenant s!mctures, as well as underground pipelines. A 7-foot deep sump will also be constructed iu the south portion of the site. Structural design of the tanks will be done in accordance with API-650. The project site will be surrounded by a containment wall approximately up to 8.0 feet high. The containment wall along northern and eastern boundaries of the facility will retain fill slopes with inclinations of 2 to 1 (horizontal to vertical) on flatter. Two access ramps will be constructed at the site. We understand that the site will be graded to approximate elevation of +20 feet (MSL Datum). We further understand that planned grading of the site will involve excavation of up to 5 feet below the present grade in the northern portions of the site and raising the present grade by up to approximately 2 feet in the southwestern portion of the site. Asphalt concrete or Portland cement concrete are considered for pavement of the containment area. The location and layout of the proposed facility are shown on the Site Plan (Figure 1). BACKGROUND INFORMATION Woodward-Clyde Consultants has performed several geotechnical investigations for different parts of the Encina Power Plant site. Some of the results of these earlier investigations were considered in this study. A list of reports reviewed for our present geotechnical investigation is presented below: a/vbl -2- Project No. 87512373-SIOl 0 “Phase II Liquefaction Potential Studies, Encina Power Plant, Carlsbad, California”, June 19, 1986; 0 “Liquefaction Potential Study, Encina Power Plant, Carlsbad, California”, December 17,1984; 0 “Final Report of Engineering Observation of Grading and Testing of Compacted Fill, Wastewater Treatment Ponds, Encina Power Plant, Carlsbad, California”, December 8, 1978; and 0 “Soil Investigation for the Proposed SDG&E Waste Water Treatment Facility, Encina Plant, Carlsbad, California”, May 24, 1976. FIELD AND LABORATORY INVESTIGATIONS Our field investigation included making a visual reconnaissance of the existing surface conditions, making four exploratory borings on May 3 and 4, 1988, and obtaining representative soil samples. The borings were advanced to depths ranging from 15 to 64 feet. The locations of the borings are shown on Figure 1. A Key to Logs is presented in Appendix A as Figure A-l. Final logs of the borings are presented in Appendix A as Figures A-2 through A-7. The descriptions on the logs are based on field logs, sample inspection, and laboratory test results. Results of laboratory tests are shown at the corresponding sample locations on the logs and in Appendix B. The field investigation and laboratory testing programs are discussed in Appendices A and B. SITE CONDITIONS Geologic Setting The Encina Power Plant site is located on erosional remnants of a coastal mesa surface. Prior to development of SDG&E’s Encina facility, a channel of Agua Hedionda Lagoon extended roughly southeasterly into the study area. Eased upon historical aerial akbl -3- Project No. 87512373-SIOl photographs and old topographic maps, the approximate shoreline of the channel, referred to as the slough area is shown on Figure 1. The surface of the slough apparently was essentially flat-lying at or within several feet of Mean Sea Level. The slough area and relatively low-lying mesa areas located immediately north and south of the slough were later filled to provide level pads for power plant facilities. Site Conditions The site is currently a paved area that provides access to the fuel oil tanks located in the northeastern portion of the power plant site. The study area is bound on the west and southwest by fill slopes adjacent to existing wastewater ponds. To the south, beyond the paved area a fill slope descends to a lower level at which numerous oil supply lines run above ground in a northeasterly direction. A 96-inch diameter storm drain extends under the general site area in a west-northwesterly direction. The storm drain terminates in the slough roughly 100 feet northwest of the surface drain in the northwest comer of the paved area. To the northeast, the study area is bounded by fill slopes that are adjacent to fuel oil tanks. The site plan provided to us indicates that me slopes at the site am mostly 2:l (horizontal to vertical) or flatter with some occasional portions having inclinations of 1.5: 1. Utilities present in the general site area include the above mentioned storm drain, water lines related to the irrigation of the various fill slopes, and a high voltage line located along the south edge of the site area. Subsurface Conditions As revealed by our borings, the project site is underlain by approximately 18 to 24 feet of man-made fill. The fill overlies approximately up to 40 feet of Holocene estuarine deposits within the slough area. The Holocene estuarine deposits in the slough area and the fill soils outside the slough are underlain by the Santiago Formation. qlvbl c 4 Project No. 87512373-SIOl Fill Most of the fill soils underlying the study area were probably placed during the earlier phases of the Encina Power Plant development that included construction of the Power House Units Nos. 1, 2 and 3, the 138 KV Switching Station and the West Fuel Tank Farm. No records of placement of this fill within the study area is available to US. Record of placement and compaction testing of the 96-inch storm drain backfill is included in our December 8,1978 report. The fill typically consists of silty to clayey sands with some gravels and asphalt fragments. The fill material appears to be relatively compact. Penetration blow counts recorded in fill during our field investigation range from 13 through 59 blows per foot. Holocene Estuarine Deposits The Holocene estuarine deposits that underlie the fill soils within the former slough area can be generally characterized as a sequence of sand, silty sand and silt with occasional layers and/or lenses of clay. For this study, the estuarine deposits were divided into an upper and lower layer. This division was introduced in our earlier studies for the wastewater ponds area described in our December 17,1984 and June 19,1986 reports. The Upper Estuarine Deposits underly fill soils generally in the southeast part of the former slough area. In the northwest portion of the slough these soils were undercut during construction of the protective berm along the shore of the lagoon. The Upper Estuarine Deposits typically consist of medium dense silty tine sand, clayey silt and occasional thin layers of plastic organic-rich clay. Some of the soils of the Upper Estuarine Deposits appear to have been moved and mixed. Possible causes for presence of these mixed soils were discussed in our May 24,1976 report. The Lower Estuarine Deposits consist predominantly of dense to very dense silty fine sand. These soils underly the soils of the Upper Estuarine Deposits and the fill soils in the northwest portion of the slough where the Upper Estuarine Deposits were undercut as discussed above. c a/vbl -5- Project No. 875123734101 Santiago Formation The erosional channel of the former slough area is cut down into Eocene sandstone of the Santiago Formation. The Santiago Formation underlies the entire site at depth. Groundwater The groundwater table was encountered at approximate elevations ranging from +2.0 to +2.5 feet (MSL Datum) at the time of our exploration. Groundwater levels at the project site are expected to be influenced by the tidal fluctuations. DISCUSSIONS, CONCLUSIONS, AND RECOMMENDATIONS The discussions, conclusions, and recommendations presented in this report are based on the information provided to us, results of our field and laboratory studies, analyses, and professional judgment. Potential Geologic Hazards Faulting and Ground Breakage Our earlier seismic studies for the Encina Power Plant site as well as review of published fault maps and “Report of the Evaluation of Maximum Earthquake and Site Ground Motion Parameters Associated with the Offshore Zone of Deformation, San Onofre Nuclear Generating Station”, dated June 1979 revealed no indication of the faults extending through the site of the proposed facility. Ground Shaking We understand that seismic design of the wastewater facility will be done in accordance with API-650. Levels of ground shaking specified in the above document are determined, a/vbl -6- wlodward-clydeconsultants Project No. 87512373SIOl based on the Seismic Zone Map, Figure E-l and local soil conditions per Table E-2. We recommend that Soil Profile Type C be used for seismic design of the subject facilities. Liquefaction In our earlier studies we have performed analyses of soil liquefaction potential for the site of the Encina Power Plant. Results of these analyses are presented in our aforementioned reports dated December 17,1984 and June 19,1986. The above reports indicate that some granular soils of the Upper Estuarine Deposits within the former slough area may experience seismic-induced soil liquefaction. Liquefaction potential of other geologic units present at the site of this project was judged to be very low. Based on our earlier studies and this. investigation the Upper Estuarine Deposits are estimated to be present in the southwest portion of the project site. Our present subsurface investigation did not reveal loose or medium dense granular soils susceptible to liquefaction within the Upper Estuarine Deposits in that area. However, the geologic nature of the Upper Estuarine Deposits suggests that such loose or medium dense soils may be present within this geologic unit. If liquefaction occurs at the project site, it can probably generate some localized ground subsidence and differential settlement. In our opinion, occurrence of liquefaction-related sand boils and ground rupture is unlikely due to the presence of approximately 15 to 20 feet of nonliquefiable overburden. The overburden soils will also, in our opinion mitigate potential differential settlements. Estimated values of potential liquefaction related ground settlement are presented further under “Settlement”. Our field and laboratory investigation indicates that fill soils and estuarine deposits are predominantly composed of nonexpansive to slightly expansive sands, silty and clayey sands with minor amount of clays. Fill soils appear to be moderately compact. As no record of till placement and testing is available to us, we can not preclude a possibility of poorly compacted till present at some locations within the project site. Soils of the Upper a/vbl -7- Project No. 87512373-SIOl Estuarine deposits may be locally compressible and in our opinion, they may generate settlement if subject to loads. Granular portion of the Upper Estuarine Deposits may be susceptible to seismic induced soil liquefaction as described above. Soils of the Santiago Formation predominantly consist of very dense sands and silts. These soils are locally cemented. Permanent groundwater table was encountered at approximate elevations +2.0 to +2.5 feet (MSL Datum). This groundwater table is, in our opinion subject to tidal fluctuations. Grading We recommend that all grading be performed in accordance with the attached Guide Specifications for Earthwork (Appendix C). We recommend that Woodward-Clyde Consultants review grading plans for compliance with the recommendations of the report. We recommend that a pre-construction conference be held at the site, with SDG&E representatives, contractor and geotechnical engineer in attendance. Special soil handling and grading procedures can be discussed at that time. To provide more uniform support for structure foundations we recommend that existing till to a depth at least 3 feet below the bottom of the foundations be removed, replaced and recompacted to a minimum relative compaction of 95%. That removal and recompaction should extend to at least 3 feet beyond the exterior foundation lines. It is our opinion that the excavated soil can generally be reused as compacted fill. We recommend that potentially expansive, clayey soil, if encountered during the grading operations, not be put within the upper 2 feet of the subgrade or within the zone of recompaction beneath foundations. We recommend that all grading be observed by and compacted fills tested by Woodward- Clyde Consultants. a/vbl -8- E’roject No. 87512373-SIOl We estimate that proposed fill slopes of up to 30 feet high with inclinations of 2 to 1 (horizontal to vertical) or flatter have calculated average factors of safety for deep-seated failure of 1.5 or greater for static conditions. We also estimate that 2 to 1 till slopes of up to 20 feet high, located behind a retaining wall of up to 8 feet in height, have calculated average factors of safety for deep-seated failure of 1.5 or greater for static condition. Fill slopes if they become saturated may experience localized surficial sloughing, especially those having inclinations of 2 to 1. Sloughing of the fill slopes can be reduced by backrolling fill slopes at frequent intervals. As a minimum, we recommend that all fill slopes be trackwalked so that a dozer track covers all surface at least twice. We recommend that all slopes be planted, drained and maintained. Drainage We recommend that positive measures be taken to properly finish grade the lot after structures and other improvements are completed so that drainage water and roof water is collected in gutters and downspouts, and together with any other water is directed away from foundations. Foundations We understand that reinforced concrete mat foundations are considered for the support of most of the structures at the proposed facility. It is our opinion that a mat foundation would significantly mitigate potential differential settlement that may develop under static loads or earthquake loading conditions. Our settlement evaluation is discussed further in this report. We recommend that the properly compacted subgrade fill soil under the mat be assumed to have a design modulus of subgrade reaction of 150 ton/fts. a/vbl -9- hoject No. 87512373-SIOl Soil Bearine Cauacitv We estimate that reinforced concrete mat foundations for the tanks, continuous footings for the containment walls and spread footings for miscellaneous structures located outside the former slough area as shown in Figure 1 can be designed for the maximum allowable soil bearing pressure of 4000 psf (dead plus live load). We recommend the allowable soil bearing pressure of 3,000 psf for structures located within the slough area. The above bearing pressures are applicable to structures placed on a 3-foot thick mat of recompacted fiil as recommended above. In our opinion, these allowable soil bearing pressures can be increased by one-third for wind and seismic loads. All tank footings should have a minimum width of 24 inches and a minimum depth of 18 inches below the lowest adjacent grade. Footings for the containment wall and other light structures should have a minimum width of 36 inches and a minimum depth of 12 inches below the lowest adjacent grade. Estimated Settlements We estimate that the total post-construction settlements for the proposed structures designed in accordance with the above recommendations will be up to approximately 2 inches with differential settlements generally less than one-half of the total settlement. Due to the predominantly granular nature of subsurface soils encountered during our field investigation, it is our opinion that most of the above settlement will develop within 2 to 4 weeks after construction and filling of the tanks. To reduce the adverse effect of ground settlement on pipelines, we recommend a 2- to 4- week settlement waiting period between filling of the tanks and the pipeline construction. We further recommend that tank foundation settlement be monitored before and after filling. The settlement record should be reviewed by Woodward-Clyde Consultants prior to terminating of the settlement waiting period. We estimate that approximately 1 to 2 inches of differential settlement may develop if seismic-induced soil liquefaction occurs at the project site. akbl -lO- Project No. 87512373-SIOl Retaining Walls We recommend that all wall backfill be composed of select granular material. For this condition, and assuming that the top of the wall is capable of rotating a lateral distance of at least 0.1 percent of the height of the wall, we have calculated equivalent fluid weights for design of the retaining walls with different slope inclinations behind the wall. Results of these calculations are summan ‘zed in Table 1. The values presented in Table 1 are based on the assumption that there will be no surcharge loads acting within a 45-degree plane extending up from the base of the retaining wall, and that the wall is provided with a backfill drainage system adequate to prevent buildup of hydrostatic pressures. Guide Specifications for Wall Drains are presented in Appendix D. As a minimum, we recommend a wall drainage system which includes at least a 4-inch diameter perforated pipe and at least 2 cubic feet per foot of filter material surrounding the drain as outlined in Appendix D. A possible drainage alternative is the use of geofabtics attached to the back of the wall and drained into a drain pipe at the base of the wall. Resistance to Lateral Loads To provide resistance for design lateral loads, we recommend using an equivalent fluid weight of 350 pcf for footings or grade beams poured against properly compacted granular fill. These values assume a horizontal surface for the soil mass extending at least 10 feet from the face of the footing, or three times the height of the surface generating passive pressure, whichever is greater. The upper 12 inches of material in areas not protected by floor slabs or pavement should not be included in design for passive resistance to lateral loads. If friction is to be used to resist lateral loads, we recommend using a coefficient of friction of 0.4 between soil and concrete. If it is desired to combine frictional and passive resistance in design, we recommend using a friction coefficient of 0.3. a&b1 -ll- Project No. 87512373-SIOl Pavement We understand that asphalt concrete (AC) or Portland cement concrete (PCC) pavement is being considered for use at the project site. Based on the results of our R-value test and on the general characteristics of the on-site soils observed during our soil investigation, we have assumed a design R-value of 50 for our calculations. We understand that in addition to regular light vehicle traffic expected at the facility, occasional heavy trucks used for tank cleaning will be travelling at the site. For the above traffic conditions we have assumed a Traffic Index of 6. Based on the assumed R-value and the Traffic Index we recommend 3 inches of AC over 4 inches of Class 2 aggregate base, or 6.0 inches of PCC over 4 inches of aggregate base as a pavement section. We recommend that the upper 12 inches of subgrade material consists of select granular soil. The top 6 inches of subgrade material should be compacted to at least 95 percent relative compaction. UNCERTAINTY AND LIMITATIONS We have observed only a small portion of the pertinent soil and groundwater conditions. The recommendations made herein are based on the assumption that soil conditions do not deviate appreciably from those found during our field investigation, We recommend that Woodward-Clyde Consultants review the foundation and grading plans to verify that the intent of the recommendations presented herein has been properly interpreted and incorporated into the contract documents. We further recommend that Woodward-Clyde Consultants observe the site grading, subgrade preparation under concrete slabs and paved areas, and foundation excavations. If the plans for site development are changed, or if variations or undesirable geotechnical conditions are encountered during construction, the geotechnical consultant should be consulted for further recommendations. This report is intended for design purposes only and may not be sufficient to prepare an accurate bid. California, including San Diego, is an area of high seismic risk. It is c akbl -12- Project No. 87512373-SIOl generally considered economically unfeasible to build a totally earthquake-resistant project; it is, therefore, possible that a large or nearby earthquake could cause damage at the site. Geotechnical engineering and the geologic sciences are characterized by uncertainty. Professional judgements presented herein are based partly on our understanding of the proposed construction, and partly on our general experience. Our engineering work and judgements rendered meet current professional standards; we do not guarantee the performance of the project in any respect. Inspection services allow the testing of only a small percentage of the till placed at the site. Contractual arrangements with the grading contractor should containing the provision that he is responsible for excavating, placing, and compacting fill in accordance with project specifications. Inspection by the geotechnical engineering during grading should not relieve the grading contractor of his primary responsibility to perform all work in accordance with the specifications. This firm does not practice or consult in the field of safety engineering. We do not direct the contractor’s operations, and we can not be responsible for the safety of personnel other than our own on the site; the safety of others is the responsibility of the contractor. The contractor should notify the owner if he considers any of the recommended actions presented herein to be unsafe. a/vbl -13- Project No. 87512373-SIOl TABLE 1 Estimated Active Lateral Earth Pressure for Retaining Walls in Terms of Equivalent Fluid Pressure Approximate Backfii Slope Adjacent to Wall --_ 2:l 3:l 8:1 Approximate Slope Inclination to Horizontal, o 0 26.6 19 7 Equivalent Fluid Pressure, psf 35 54 46 38 Note: Equivalent fluid pressures for slope inclination other than shown above can be found by interpolation. -. dvbl Project No. 87512373SIOl APPENDIX A FIELD INVESTIGATION Four exploratory borings were advanced at the approximate locations shown on the Site Plan (Figure 1). The drilling was performed on May 3 and 4,1988, under the direction of a geologist from our firm, using g-inch hollow-stem power auger. Samples of the subsurface materials were obtained from the borings using a modified California drive sampler (2-inch diameter and 2.5~inch outside diameter) with thin brass liners. The sampler was generally driven 18 inches into the material at the bottom of the hole by a 140-pound hammer falling 30 inches; thin metal liner tubes containing the sample were removed from the sampler, sealed to preserve the natural moisture content of the sample, and returned to the laboratory for examination and testing. The location of each boring and the elevation of the ground surface at each location were estimated by the available site plan. t&b1 c A-l Project:New Wastewater Facility-SDG&E Encina Power Plant KEY TO LOGS Date Drilled: Water Depth: MEGlJWd: Type of Boring: Type of Drill Rig: Hammer: i s r g:= 2 2 g g 5 G 0 Material 0 2 Description x;$g.gg 3: srn $ m zi 0s ‘reject No: 87512373~SlOl Woodward-Clyde Consultants s Surface Elevation: - DISTLJRBED SAMPLE LOCATlON Obtained by collecting the auger cuttings in a plastic bag. - DRIVE SAMPLE LOCATiON Sample with recorded blows per foot was obtained with a Modified California drive sampler (2’ inside diameter, 2.5’ outside diameter) lined with sample tubes. The sampler was driven info the soil at the bottom of Ihe hole with a 140 pound hammer falling 30 inches. Fill Sand Sand/Silt GS -Grain Size Distribution Analysis CC - Confined Compression Test ‘R’ - R-Value Test Figure: A-l Project:New Wastewater Facility-SDG&E Encina Power Plant Log of Boring No: 1 Date Drilled: 5-3-68 Water Depth: 16 Measured: At time of drilling Type of Boring: 6” HSA Type of Drill Rig: B-61 Hammer: 140 Ibs. at 30” drop * see Key to Logs, Fig. A-l i g f e g 5 ?i:= -F ; H s 0 9 Material Description .;;$l gjop &Z G m 28 6 0: Suriace Elevation: Approximately 20 0 3” Asphalt concrete over moist, brown. silty sand with trace gravels FlLL Moist. olive gray, clayey sand, sandy clay and silty sand. with shell fragments. asphalt fragments Wet. brown, silty fine sand Very dense, wet, gray, silty fine sand (SM), micaceous LOWER ESTURINE DEPOSITS ‘reject No: 67512373-5101 Woodward-Clyde Consultants e Figure: A-2 Project:New Wasterwater Facility-SDG&E Encina Power Plant Log of Boring No: 1 i s s z.g - g= -g s ;a E 8 &g z ‘2 cl _o G m Material Description 38 ; s? 30’ (Continued) very dense. wet. gray, silty fine sand (SM). mica- CeDUS LOWER ESTURINE DEPOSllX Dense, wet. light gray. silty fine sand (SM) with zones of poorly graded fine sand with silt (EM-SP) - l-8 43 :,.i~~ LOWER ESTURINE DEPOSlTS - .20 109 35- ;;;* i!:;y?:g>; ;;z;g$$ Very dense, wet, olive gray, silty sand (SM) with layers of clayey sand (SC) and poorly graded sand with sitt (SM-SP) LOWER ESTURINE DEPOSlTS Very dense, wet, olive gray. silty fine sand (SM) to fine sandy silt (ML) cemented SANTIAGO FORMATKIN Bottom of Boring at 50 feet 60- 65, ‘reject No: 67512373.SlOl Woodward-Clyde Consultants e Figure: A-3 . Project:New Wastewater Facility-SDG&E Enclna Power Plant Log of Boring No: 2 Date Drilled: 5-3-66 Water Depth: Not encountered Measured: At time of drilling Type of Boring: 6” HSA Type of Drill Rig: 861 Hammer: 140 # at 30’ drop * see Key to Logs, Fig. A-l F me- - 1 5 $Z 5 xzp. &g 35 s b E Material Description 0 ; ; rz g$ 8 6Z Surface Elevation: Approximately 25’ OY 3” Asphalt concrete over moist, reddish brown, silty fine sand with trace of gravel and asphalt chunks FILL 5- Moist, olive gray, siky and clayey fine sand with gravels wood, and asphalt fragments FILL lo- 15- 20- Bottom of Boring at 19.5 feet 25- 30, reject No: 67512373.SlOl Woodward-Clyde Consultants e Fgure: A-4 Project: New Wastewater Facility-SDG&E Encina Power Plant Log of Boring No: Z Date Drilled: 5-3-86 Water Depth: Not encountered Measured: At time of drilling Type of Boring: 6’ HSA Type of Drill Rig: B-61 Hammer: 140 Ibs. at 30’ drop ‘see Key to Logs, Fig. A-l i g G g g 2: b. g:= z s Material Description mYI o s 9 m 26 s;s$g‘gK tu, s 02 Surface Elevation: Approximately 24’ 0 3” Asphaii concrete over moist, olive brown, siitty sand with gravel FILL - 3-1 Moist, light gray, siily line sand and reddish brown, poorly graded fine sand with silt FILL 5- w-77 Very dense. moist, light gray brown, siity sand (SM) with brown clayey veins and zones SANTIAGO FORMATlDN Bottom of Boring at 15 feet 20- 25- 30, ‘reject No: 87512373~SlOl I Woodward-Clyde Consultants e Figure: A-5 Project:New Wastewater Facility-SDG&E Encina Power Plant Log of Boring No: 4 Date Drilled: 5-3-86 and .5-4-86 Water Depth: 19’10’ Measured: 15 hours after drilling Type of Boring: 6” HSA Type of Drill Rig: B-61 Hammer: 140 Ibs. at 30” drop * see Key to Lags, Fig. A-l J-z i 5 c g s ; -69 3;u= 2 9 5 Material Description =a 5;z$g’gg 5; 0 r2 * % g 2 0: Surface Elevation: Approximately 22.5 0 3” Asphalt concrete over moist, reddish brown, silty sand with gravels FlLL Moist, reddish brown, silty sand with light gray sandstone fragments FILL - 4-1 46 5- Moist. reddish brown. poorly graded sand with silt, with clayey sand zones, trace gravel fragments, rare asphalt fragments ‘reject No: 67512373.SlOl Woodward-Clyde Consultants e Figure: A-6 Project:New Wastewater Facility - SDG&E Encina Power Plant Log of Boring No: 1 i 1 E e 4 T$i= -g s ;rn< 2 0 G P Material Description co c m & 30’ (Continued) wet. brown, silty fine sand with siltstone and sand- 1 stone MlXED SOILS (FILLESTUARINE DEPOSlTS) UPPER ESTUARINE DEPOSITS 4 - 15 Dark gray, fat clay layer, approximately 1’ at 46.5’ LOWER ESTUARINE DEPOSlTS 1” layer of stiff, olive fat clay at approximately 59 Figure: A-7 117 97 106 I -Clyde- Project No. 87512373SIOl APPENDIX B LABORATORY TESTS The materials observed in the borings were visually classified and evaluated with respect to strength, swelling, and compressibility characteristics; dry density; and moisture content. The classifications were substantiated by performing grain size analyses and evaluating plasticity characteristics of representative samples of the soils. The strength of the soils was evaluated by considering the density and moisture content of the samples and the penetration resistance of the sampler. Compressibility characteristics were evaluated by performing a confined compression test. The suitability of soils for use as pavement subgrade was evaluated by performing an R-value test. The results of test on drive samples, except for grain size distribution, unconfined compression and R-value tests are shown with the penetration resistance of the sampler at the corresponding sample location on the Logs, Figures A-2 through A-7. The grain size distribution curves are shown in Figure B-l. The results of the confined compression test are reported in Figure B-2. The results of the R-value test, as submitted to us by Testing Engineers-San Diego are presented in Figure B-3. a/vbl B-l L UNIFIED SOIL CLASSIFICATION COBBLES Am*fa SAND SILT OR CLAY NEmL!u FME u.6. tnmx tami a IllcBs9 U.S.slurmRD~ila. 100 80 40 60 140 PO0 60 is 52 E L3D s i! k 40 2 E 20 0 1 CXAIN3IZEiINhtUUElXR SYHBGL BORING w 3 &\ DESCRPllON 0 l-8-3 SILTY FlNE SAND (GM) a 4-8-3 PGORLY GfWED SW0 (SP) Remark: 67512373 SIOl S.D.G, 81 ‘E. ENCINA POWER PLANT Woodward Clyde consultents GRAIN SIZE DISTRIBUTION mure No. B-l San Diego, CA RESULTS OF CONFINED COMPRESSION TESTS ample l-l-4 Dry knsity wf - 111 itial Water onteni % 16 huratiol 83 f II k T Dry knsit: wf - 117 :inal hter mtent L 16 kuratio 100 'essurs Psf - 4000 Caqwessicm C of Initial Heigl 4.8 0 1000 PRESSURE - psf 2000 3000 4000 5000 6.0 in cieforndtion) CONFINED COMPRESSION TESTS NEW WASTEWATER FACILITY - SIX&E ENCINA POWER PLANT DRAWN BY: cb CHECKED ev: PROJECTNO: 87512373-SIOl DATE: 6-20-88 FIGURE NO: B-2. WOODWARD-CLYDE CONSULTANTS ::@2 zr: Testing Engineers-San Diego !‘:i?! ,d 3467 Kurtz Street, PO. Box 60965, San Diego CA 92138 (619) 225-9641 .~&W 2946 Industry St., Unit 6, Oceanside, CA 92054 (619) 758-3730 JGI NO: 1285 I,~!ClDDWARD/CLYDlX CONSLILT - JOB NM: WG9l%lARD AND CLYDF CONSULTANIS ;?ND F l...OOR JOl AMJ!ESS: ALL LOCATILlNS '15511 HOTEL CIRCI-E NORT SANDIEGD, CA SAN D:CEGD, CA Y?l@Cl ATTENTION: Chuck REPORT NO: 13815 REPORT OF SOIL TERS R VALIJE: DATA I ANTS DISTRIBUTED TO: UODDUAHDlCLYDE CONSULT!iNlS H TESTINI: fNGII!EBS-SAN Dlt,CO MTE: l5/18/8~ I .::.~l:i:‘-““-~----‘~-11~I-=:~~I~=~’~~~::l~=::~~:~:~~~:~~=::=::::::3~e~=::e==~:I==3==--:.~=~~-..~.... .--....- ._ _.._.. ..~ - - --- - .I: :::: -~: A 12,:::::z.Y:‘: .3Yf:::c 2: _::=:::.===~1::~-----.~-=3= 22 7:: = -* = :: c:onl,ac:tor Pre!ss "' p.s.1. 350.0 lln:i.st P Conpaction - Z 9.7 Density -. t/Cu .Ft. 127.1 H..+d%{J+? -' !?tabiIonetar 84.0 Exud. Prrssure - P.Ci.1. h40.0 Stab. Thick - Feet 002 Expan. Press. Thick -. Feet 0,4 ,T.I. (AssaMed) 4 , s By Stab. e 300 P.S.I. Exutl. 77.0 By Expans:ion Freflsurt~ az.0 A t E q u i 1 j. b P i u n 77,o _, Sand Equivalent N/A Meterial samg’led by: CLIENT Submitted to laboratury on: 05/09/rl8 B z:<===x 350.0 10.1 127.0 a0 IO 420 IO 0 , 3 0,l C ='zI=zz 3::'rll.O 1 o.FJ 127.9 74.0 ~240.0 0.4 0.0 D =:(-=!zz:~ 3sn IO 11.4 126.3 62.0 140.b 0 I tr : Dc?s~~ibecl as:. SAt4Pl.E NO: SK+l , BROWN MI:~.DILlM TII FINE. S:l.L.TY 5fiNI.' WITl~l Rl3CI! Sampled pron: ti:NCINA T'&NK c Figure B-3 w3odwardaydeconsultants Project No. 87512373-SIOl APPENDIX C GUIDE SPECIFICATIONS FOR EARTHWORK SDG&E Encina Power Plant New Wastewater Facility NOTE: These specifications are provided as a guide for preparation of the final grading specifications for the project, which with the plans constitute the project documents. These guide specifications are twt intendedfor use as final grading specifications. 1. GENERAL 1.1 The work of the Contractor covered by these specifications consists of furnishing labor and equipment and performing all operations necessary to remove deleterious and undesirable materials from areas of grading, to properly prepare areas to receive fill, and to excavate and fill to the lines and grades shown on the plans or as directed in writing by the Owner. 1.2The Contractor shall perform the work in strict accordance with these specifications and the Contractor shall be responsible for the quality of the finished product notwithstanding the fact that the earthwork may be observed and tests made by a Geotechnical Engineer. Deviations from these specifications will be permitted only upon written authorization from the Owner. 1.3 The data contained in the geotechnical report and in any following addenda indicating subsurface conditions are not intended as representations or warranties of the accuracy or continuity of subsurface conditions between soils borings. It shall be expressly understood that the interpretations or conclusions drawn from such data are the responsibility of the Contractor. 2. DEFINITIONS 2.1 Contractor shall mean the contractor performing the earthwork. 2.2- shall mean the owner of the property or the party on whose behalf the earthwork is being performed and who has contracted with the Contractor to have the earthwork performed. 2.3/Civil Engineer) shall mean the engineer who has prepared the grading plans and who is the Owner’s representative concerning the configuration, quantities and dimensions of the earthwork and who usually sets basic surveying data at the site for the Contractor’s conformance. 2.4Geotechnical Eneineer shall mean a licensed civil engineer authorized to use the title “Geotechnical Engineer” in accordance with Section 6736.1, Chapter 7, a/vbl C-l Project No. 87512373-SIOl Division 3, State of California Business and Professions Code. The Geotechnical Engineer shall be responsible for having representatives on site to observe and test the Contractor’s work for conformance with these specifications. 2.5 Green Book shall mean the most recent edition of the Standard Specifications for Public Works Construction, prepared by the Joint Cooperative Committee of the Southern California Chapter, American Public Works Association, and Southern California Districts, Associated Contractors of California. 2.6 Standard Suecial Provisions shall mean the most recent edition of the Standard Special Provisions, prepared by County of San Diego, Department of Public Works. 3. OBSERVING AND TESTING 3.1 The Geotechnical Engineer shall be the Owner’s representative to observe and make tests during the foundation preparation, filling, and compacting operations. 3.2 The Geotechnical Engineer shall make field density tests in the compacted fill to provide a basis for expressing an opinion as to whether the fill material has been compacted to at least the minimum relative compaction specified. The basis for this opinion shall be that no tests in compacted or recompacted areas indicate a relative compaction of less than that specified. Density tests shall be made in the compacted material below any disturbed surface. When these tests indicate that the density of any layer of till, or portion thereof, is below the specified density, the particular layer or area representative by the test shall be reworked until the specitied density has been achieved. 3.3 Testing shall conform to the following standards as pertinent: l ASTM D2922-81, “Density of Soil and Soil-Aggregate in place by Nuclear Methods (Shallow Depth)” l ASTM D3017-78, “Moisture Content of Soil and Soil-Aggregate in place by Nuclear Methods (Shallow Depth)” l ASTM D15.5682, “Density of Soil in place by the Sand-Cone Method” l ASTM D1557-78, “Moisture-Density Relations of Soils and Soil - Aggregate Mixtures Using a lo-lb. (4.54 kg) Rammer and 18-in. (457 - mm) Drop,” Methods A, B, and C. l AASHTO T 224-86, “Correction for Coarse Particles in the Soil ’ Test.” a/vbl c c-2 Project No. 87512373SIOl 4. CLEARING AND PREPARING AREAS TO BE FILLED 4.1 Clearing and grubbing shall be in accordance with Section 300-l of the Green Book and, in addition, all trees, brush, grass, and other objectionable material shall be collected from areas to receive fill and disposed of off-site prior to commencement of any earth moving so as to leave the areas that have been cleared with a neat and fmished appearance free from debris. 4.2 All loose or porous soils shall be removed or compacted as specified for fill. The depth of removal and recompaction shall be approved in the field by the Geotechnical Engineer. Prior to placing fill, the surface to be filled shall be free from uneven features that would tend to prevent uniform compaction by the equipment to be used. It shall then be plowed or scarified to a depth as required and in no case less than a minimum depth of 6 inches. 4.3 Where the exposed slope is steeper than 6 horizontal to 1 vertical, or where specified by the Geotechnical Engineer, the slope of the original ground on which the fill is to be placed shall be stepped or keyed by the Contractor as shown on the figure below. The steps shall extend completely into the underlying formational materials or, where formational material is not present, into previously compacted till. Oriqinal qround NOTES: The outside edge of bottom key “A” shall be not less than 2 feet in depth into formational soil or no less than 5 feet into previously compacted fill. The minimum width of benches “B” shall be at least l-1/2 times the width of the compaction equipment, and not less than 10 feet. r a/vbl c-3 Project No. 87512373-SIOl 4.4 After the foundation for the till has been cleared, plowed or scarified, it shall be disked or bladed by the Contractor until it is uniform and free from large clods, brought to the specified moisture content, and compacted as specified for till. 5. SUBGBADE PREPARATION IN PAVEMENT ABEAS 5.1 Subgrade preparation shall be in accordance with Section 301-l of the Green Book, except that relative compaction of subgrade shall be in accordance with Section 12 of these specifications. Scarification and recompaction requirements may be waived by the Geotechnical Engineer in subgrade areas with naturally cemented formational soils. 5.2All areas to be paved shall be proofrolled in accordance with Section 301-1.3 of the Standard Special Provisions. 6. MATERIALS - GENERALPILL 6.1 Materials for compacted fill shall contain no rocks or hard lumps greater than 6 inches in maximum dimension and shall contain at least 40% of material smaller than l/4 inch in size. Material of a perishable, spongy, or otherwise improper nature shall not be used in tills. 6.2 Select soil, to be used at finish grade to the depths and at the locations specified on the grading plans, shall consist of material that contains no rocks or hard lumps greater than 6 inches in maximum dimension and that has an Expansion Index of 30 or less when tested in accordance with UBC Standard 29-2. 6.3 Samples of materials to be used for fill shall be tested in the laboratory by the Geotechnical Engineer in order to evaluate the maximum density, optimum moisture content, classification of the soil, and expansion index, as required 6.4 During earthwork operations, soil types other than those analyzed in the report of the geotechnical investigation may be encountered by the Contractor. ‘lhe Fo;p:echnical Engineer shall be consulted to determine the suitability of these 7. MATERIALS - PAVEMBNT SUBGRADE 7.1 Pavement subgrade shall be defined as the top 12 inches of soil, excluding aggregate base, in areas to be paved with asphalt concrete or Portland cement concrete. 7.2 Materials for pavement subgrade shall contain no rocks or hard lumps greater than 6 inches in maximum dimension, shall contain at least 40 percent of material smaller than l/4 inch in size, and shall have an Expansion Index of 30 or less when tested in accordance with UBC Standard 29-2. Material of a perishable, spongy or otherwise improper nature shall not bc used in fills. c a/vbl Project No. 87512373-SIOl 8. MATERIALS - TRENCH BACKPILL 8.1 Trench backfill materials above pipe bedding shall be in accordance with Section 306- 1.3 of the Green Book. 8.2 As an alternative, cement slurry may be used to backfill trenches. The slurry shall have a minimum cement content of two sacks per cubic yard within the building limits and zone of influence of foundations and other settlement - sensitive structures. A minimum one sack per cubic yard slurry shall be used elsewhere. 9. MATBRIALS - WALL BACKPILL 9.1 Wall backfill materials shall be in accordance with Section 300-3.5 of the Green Book. 10. COMPACTION EQUIPMENT 10.1 Compaction shall be accomplished by sheepsfoot rollers, vibratory rollers, multiple-wheel pneumatic-tired rollers, or other types of compaction equipment made specifically for the purpose of compacting soils. Equipment shall be of such a design that it will be capable of compacting the fill to the specified density at the specified moisture content. 11. PLACING, SPREADING, AND COMPACTING GENERAL PILL MATERIAL 11.1 After each layer has been placed, mixed, and spread evenly, it shall be thoroughly compacted by the Contractor to a relative compaction that is indicated by test to be not less than 90 percent. Relative compaction is defined as the ratio (expressed in percent) of the in-place dry density of the compacted fill divided by the maximum laboratory dry density evaluated in accordance with the ASTM D1557-78. Unless otherwise specified, till material shall be compacted by the Contractor while at a moisture content at or above the optimum moisture content determined in accordance with the above test method. 11.2 The fill material shall be placed by the Contractor in layers that, when compacted, shall not exceed 6 inches. Each layer shall be spread evenly and shall be thoroughly mixed during the spreading to obtain uniformity of moisture and material in each layer. The entire fill shall be constructed as a unit, in nearly level lifts starting up from the lowest area to receive fill. Compaction shall be continuous over the entire area, and the equipment shall make sufficient uniform trips so that the desired density has been obtained throughout the entire fill. 11.3 When the moisture content of the fill material is &&J that specified by the Geotechnical Engineer, water shall be added by the Contractor until the moisture content is as specified. c a/vbl c-5 Project No. 87512373-SIOl 11.4 When the moisture content of the fill material is & that specified by the Geotechnical Engineer or too wet to achieve proper compaction, the fill material shall be aerated by the Contractor by blading, mixing, or other satisfactory methods until the moisture content is as required to permit compaction. 11.5 Properly compacted fill shall extend to the design surfaces of fill slopes. The surface of fill slopes shall be compacted in accordance with Section 11.1 of these specifications. 12. PLACING, SPREADING, AND COMPACTING FILL MATERIAL IN STRUCTURE AREAS 12.1 Structure areas are defined as areas extending at least 5 feet beyond the exterior buildng lines in plan, and at least 5 feet below the bottom of a footing in depth, or as specified by the Engineer. 12.2 Fill material in structure areas shall be placed in accordance with Section 11 of these specifications, except that this material shall be compacted to a relative compaction that is indicated by test to be not less than 95 percent. 13. PLACING, SPREADING, AND COMPACITNG PAVEMENT SUBGRADE 13.1 Subgrade materials shall be placed, spread, and compacted in accordance with Section 11 of these specifications, except that the top 6 inches of subgrade material shall be compacted to a relative compaction that is indicated by test to be not less than 95 percent. 14. PLACING AND COMPACTING TRENCH BACKFILL 14.1 14.2 14.3 14.4 Backfilling and compacting shall be in accordance with Section 306-1.3 of the Green Book, except that jetting or flooding shall not be allowed and that all backfill shall be compacted to a relative compaction that is indicated by test to be not less than 90 percent. Backfill material in structure areas shall be compacted to a relative compaction not less than 95 percent. All trenches 5 feet or more in depth shall be sloped or shored in accordance with OSHA safety requirements. Trenches less than 5 feet in depth shall also be so guarded when examination indicates hazardous ground movement may be expected. No compaction testing shall be required for portions of trenches backfilled with cement slurry. a/vbl Project No. 87512373-SIOl 15. PLACING AND COMPACTING WALL BACKFILL 15.1 Backfilling and compacting shall be in accordance with Section 300-3.5 of the Green Book, except that jetting or flooding shall not be allowed. 15.2 Wall backfill material in structure areas shall be compacted to a relative compaction not less than 95 percent. 15.3 The Contractor shall be responsible for using equipment capable of compacting the backtill to the specified relative compaction without damaging adjacent walls or other existing improvements. 16. PROTECTION OF WORK 16.1 During construction, the Contractor shall properly grade all excavated surfaces to provide positive drainage and prevent ponding of water. When earthwork operations are interrupted, the Contractor shall reestablish specified compaction to the depth necessary before placing new fill. The Contractor shall control surface water to avoid damage to adjoining properties or to finished work on the site. The Contractor shall take remedial measures to prevent erosion of freshly graded areas and until such time as permanent drainage and erosion control features have been installed. 16.2 After completion of the earthwork and when the Geotechnical Engineer has finished observation of the work, no further excavation or filling shall be done except under the observation of the Geotechnicai Engineer. a/vbl c-7 Project No. 87512373-SIOl I. II. III. IV. a/vbl APPENDIX D GUIDE SPECIFICATIONS FOR WALL DRAINS DESCRIPTION Subsurface drains consisting of filter gravel with perforated pipe shall be installed as shown on the plans in accordance with these specifications, unless otherwise specified by the engineer. MANUFACTURE Subsurface drain pipe shall be manufactured in accordance with the following requirements. Perforated corrugated metal pipe, clay tile, asbestos cement pipe, PVC pipe, or ABS pipe shall conform to the AASHTO Designations M36, M65, M189, and ASTM Designations 1785 and 2751, respectively. FILTERMATERIAL Filter material for use in backfilling trenches around and over drains shall consist of clean, coarse sand and gravel or crushed stone conforming to the following grading requirements. Sieve Size Percentage Passing Sieve 11 g 100 90 - 100 II 40 - 100 4 25 - 100 8 18 - 33 :i 5- 15 o- 7 200 o- 0 This material generally conforms with Class 2 permeable material in accordance with Section 68-1.025 of the Standard Specifications of the State of California, Department of Transportation. LAYING Trenches for drains shall be excavated to a minimum width equal to the outside diameter of the pipe plus 1 foot and to the depth shown on the plans or as directed by the engineer. The bottom of the trench shall then be covered full width by 4 inches of filter material and the drainpipe shall be laid with the perforations at the bottom and sections shall be joined with couplers. The pipe shall be laid on a minimum slope of 0.2 percent. D-1 wmdwardaydeconsultants Project No. 87512373-SIOl bottom and sections shall be joined with couplers. The pipe shall be laid on a minimum slope of 0.2 percent. After the pipe has been placed, the trench shall be backfilled with filter material to the elevation on the plans, or as directed by the engineer. a/vbl D-2 Project No, 87512373-SlQl TYPICAL SECTION Impervious Soil 18" minimum Waterproof !-lembran Filter Material 16" minimum 4" Diameter Perfora Pipe Plastic Film or Building Paper ,e lted n-2