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Home My WebLink About70-4-28A; Encina Power Plant Unit No. 4; Encina Power Plant Unit No. 4; 1970-06-24BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS FOUNDATIONS 6741 EL CAJON BOULEVARD SAN DIEGO. CALIFORNIA 92115 PHILIP HENKING BENTON PRESIDENT - CIVIL ENGINEER June 24, 1970 SAN DIEGO: 583-S6S4 LA MESA: 469-S654 Pioneer Service & Engineering Co. Riverside Plaza Building 2 North Riverside Plaza Chicago, Illinois 60606 Attention: Subject: Mr. S. P. Gil Structural Engineer Project No. 70^-28A Soils Investigation San Diego Gas & Electric Company Encina Power Plant Unit No. 4 Carlsbad, California Gentlemen: In accordance with our previous telephone conversation,! am enclosing prints of Drawings 2 to 21, inclusive, for subject project, each entitled "Summary Sheet, " and representing the Boring Logs for Holes 1 to 6, inclusive. The locations of the holes, number designa- tion, and elevations are as provided to us by the San Diego Gas & Electric Company. The Laboratory Tests have not been completed so the information provided on the Summary Sheets is limited to visual classification of the soils in the field and the drive energy required to obtain the undisturbed samples. I am also enclosing Appendix B which describes the method used for obtaining undisturbed samples. If we can be of help in interpreting this limited amount of information gathered so far, please phone or write and we shall respond promptly. Respectfully submitted, BENTON ENGINEERING, INC. Distr: (1) Addressee (1) San Diego Gas & Electric Company Attention: Carl E. May, Senior Engi William G. Catlin, Civil Engineer 39f%»^-^4»i*M i '.* -l-ikSItr>JxK, g&tTC-i, .-_i . l?}W*jJ \ •••*/ SOILS INVESTIGATION San Diego Gas & Electric Company Encina Power Plant Carlsbad, California For the San Diego Gas & Electric Company Project No. 70-4-28A July 14, 1970 BENTON ENGINEERING, INC. r- % BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS FOUNDATIONS 6741 EL CAJON BOULEVARD SAN DIEGO. CALIFORNIA 92115 PHILIP HENKING BENTON PRESIDENT - CIVIL ENGINEER July 14, 1970 SAN DIEGO: 583-5654 LA MESA: 469-5654 San Diego Gas & Electric Company P. O. Box 1831 San Diego, California 92112 Attention: Gentlemen: Mr. C. E. May Senior Engineer This is to transmit to you one copy of our report entitled, "Soils Investigation, Encina Power Plant Unit No. 4, Carlsbad, California," dated July 14, 1970 We are transmitting under separate cover 3 copies Via Air Mail, this date, to Pioneer Service & Engineering Company, to the Attention of Mr. Stanley Gil. Also one copy is being mailed to Mr. C. Hjalmarson and one copy to Mr. John Burton of the San Diego Gas & Electric Company. If you should desire any further information, or if you have any questions concerning any of the data presented in this report, please contact us. Very truly yours, BENTON ENGINEERING, INC. Philip H. Berrton, Civil Engineer TABLE OF CONTENTS SOILS INVESTIGATION Page Nos. Introduction 1 Field Investigation 2 Laboratory Tests 2 to 4, inclusive DISCUSSION 1. Storage Tank Area Boring No. 1 5 Boring No. 2 5 Boring No. 3 6 Boring No. 4 6 2. Power Plant Area Boring No. 5 6 and 7 Boring No .6 7 and 8 CONCLUSIONS AND RECOMMENDATIONS Fuel Oil Storage Structures 8 to 10, inclusive Power House Unit No. 4 10 and 11 Construction 12 and 13 Drawings and Appendices List 14 DRAWINGS Drawing No. Location of Test Borings 1 Summary Sheers 2 to 21, inclusive Consolidation Curves 22 to 25, inclusive Triaxial Compression Test Results 26 Slope Stability Analyses 27 and 28 APPENDICES Standard Specifications for Placement of AA Compacted Filled Ground Unified Soil Classification Chart A Sampling B BENTON ENGINEERING. INC. . ttj PHI-LIP HENKING BENTON PRESIDENT - CIVIL ENGINEER BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS FOUNDATIONS ' 6741 EL CAJON BOULEVARD •AN DIEGO. CALIFORNIA O2115 SOILS (INVESTIGATION SAN DIEGO: 583-5654 LA MESA: 469-5654 Introduction This is to present the results of a Soils Investigation conducted at the site of the proposed expansion of the Encina Power Plant of the San Diego Gas & Electric Company located on Carlsbad Boulevard north of Cannon Road in Carlsbad, California. The objectives of the invest- igation were to determine the existing soil conditions and physical properties of the soils so that recommendations could be made for safe and economical design of foundations, stable excavation slopes, allowable passive pressures of soils, and any other information that might affect the design and construction of the proposed structures. In order to accomplish these objectives, six borings were drilled at the designated locations and undisturbed and loose samples were obtained for laboratory testing. It is understood that the proposed project anticipates fuel oil storage tanks, 25 to 35 feet in height and 240 to 260 feet in diameter, with a maximum anticipated soil pressure of 3,000 pounds per square foot. It further anticipates adding Unit No. 4 to the Power House with a maximum anticipated column load of 1500 kips distributed over a mat foundation. The average unit pressures to be imposed beneath the mat foundation are to be on the order of 2800 to 3700 pounds per square foot. The tanks may be depressed 15 to 25 feet below existing grade for appearance pur- poses and the bottom of the foundation elevation of the power house is anticipated to be approx- imately Elevation -14 feet under the main portion and approximately Elevation -21 feet in the cooling water entrance structure area. c -2-'v, Field Investigation Six borings were drilled with a truck-mounted rotary bucket-type drill rig at the approximate locations shown on the attached Drawing No. 1, entitled "Location of Test Borings." The borings were drilled to depths of 37.5 to 93.0 feet below the existing ground surface. A continuous log of the soils encountered in the borings was recorded at the time of drilling and is shown in detail on Drawing Nos. 2 to 21, inclusive, each entitled "Summary Sheet." The soils were classified by visual and textural examination in accordance with field procedures set forth on the Unified Soil Classification Chart. A simplified description of this classification system is presented in the attached Appendix A at the end of this report. Undisturbed samples were obtained at frequent intervals in the soils ahead of the drill- ing. The drop weight used for driving the sampling tube into the soils was the "Kelly" bar of the drill rig which weighs 1623 pounds, and the average drop was 12 inches. The weight below 25 feet varied with the weight of inside Kelly bar and the number of drill stems used. The general procedures used in field sampling are described under "Sampling" in Appendix B. Laboratory Tests Laboratory tests were performed on all undisturbed samples of the soils in order to deter- mine the dry density, moisture content, and shearing strength. The direct shear tests conducted on samples below depths of estimated excavation were reduced to allow for the weight of over- burden to be removed. The results of these tests are presented on Drawing Nos. 2 to 21, inclusive. Consolidation tests were performed on representative samples in order to determine the load-settlement characteristics of the soils and the results of these tests are presented graph- ically on Drawing Nos. 22 to 25, inclusive, each entitled "Consolidation Curves." BENTON ENGINEERING, INC. * -3- , ^•f •* Direct shear tests were performed on selected undisturbed samples that were saturated and drained prior to testing. The results of these tests are presented below: Normal Load in kips/sq ft 0.5 1.0 2.0 0.5 1.0 2.0 1.0 2.0 4.0 Shear Load kips/sq ft 0.60 1.06 2.23 0.80 1.53 2.86 1.21 2.31 6.88 Angle of Internal Friction Degrees 45 * 45 * 45 * Apparent Cohesion Ib/sq ft 75 100 100 Boring 2, Sample 2 Depth: 9.0 Boring 3, Sample 3 Depth; 14.0 Boring 5, Sample 9 Depth: 36 * Arbitrarily reduced In addition to the above laboratory tests, an expansion test was performed on one of the clayey soils encountered to determine its volumetric change characteristics with change in moisture content. The recorded expansion of the sample is presented as follows: Depth of Boring Sample Sample, Soil No. No. in Feet Description Percent Expansion Under Unit Load of 500 Pounds per Square Foot from Air Dry to Saturation 1 7 31 Gray silty claystone 4.30 The general procedures used for the laboratory tests are described briefly in Appendix B. An Atterberg Limit test was performed on the most clayey soil encountered to further identify its classification and the results are snown below. Boring No. 1, Sample 7 Depth: 31.0 feet Liquid Limit 54.8 Plastic Limit 22.8 Plasticity Index 32,0 BENTON ENGINEERING, INC. - -4- '"•••* •* Unconfined compression tests were performed on selected samples of the soils in order to determine more accurately the cohesive strength of the particular soil. Boring No. 1 1 2 3 4 5 5 6 6 6 6 Sample No. 3 5 4 2 1 5 6 2 4 7 10 Depth in Feet 14 21 19 8 4 23 1/2 26 10 23 39 47 Cohesion Ib/sq ft 5250 9500 7300 190 2070 11800 1200 210 3750 5900 1900 Triaxial compression tests were performed on 3 samples of similar soil from Boring 5 in order to more accurately establish the values of cohesion and angle of internal friction at the Power Plant location. The Mohr's Circle Diagram is presented on Drawing No. 26 and the results are set forth below: Boring 5, Sample 7 Depth: 29 Boring 5, Sample 9 Depth: 32 Boring 5, Sample 10 Depth: 39 Confining Pressure in p.s.i. 7.5 15.0 30.0 Peak Load in p.s.i, 100 155 211 Angle of Internal Friction 38,9< Cohesion Intercept 16p.s.i. 2300 p.s.f. BENTON ENGINEERING, INC. DISCUSSION Soil Strata 1. Storage T-ink Area Boring No. 1 Loose silt/ fine to medium sand was encountered to a depth of 1.0 foot, underlain by very firm si I ty fine to medium sand between 1 .0 and 2.5 feet, very firm cemented slightly silty fine to medium sand between 2.5 and 4.0 feet, very firm slightly silty fine to medium sand between 4.0 and 8.8 feet with some gravel to 2 inches between 8. 1 and 8.8 feet, very firm lean clayey fine to medium sand between 8.8 and 12.0 feet merging to very firm silty fine to medium sand between 12.0 and 30.6 feet with some lenses of silty clay around 24.0 feet in depth and 6 inch stratum of lime cemented sandstone at 29.0 feet in depth. A very firm clayey siltstone was found between 30.6 and 34.5 feet, and very firm slightly silty fine to medium sand was found between 34.5 and 60.0 feet, the bottom of the excavation, with occasional layers of slightly silty fine sand near 36 feet in depth and a thin lens of silty very fine sand and marginal silt at 51 .0 feet in depth. No free ground water was encountered in Boring No. 1, during 48 hours of observation. No. 2 Silty fine to medium sand was encountered to a depth of 7.0. This was loose in con- sistency between 0 and 0.5 foot, firm between 0.5 and 1 .4 feet, and very firm between 1 .4 and 7.0 feet, underlain by compact micaceous fine to medium sand between 7.0 and 17.0, very firm silty fine to medium sand between 17.0 and 19.0 feet, very firm silty fine sand and alternating layers and lenses of some siltstone and clayey siltstone between 19.0 and 37.5 feet, the bottom of the excavation. The bottom half foot consisted of a lime cemented sandstone. Perched water seeped into the side of the boring at 17 feet, and it is probable that the water level in the boring had not yet stabilized, at 31.7 feet after 24 hours. BENTON ENGINEERING, INC. * -6- • • Boring No. 3 Silty fine to medium sand was encountered to a depth of 5.0 feet which was loose in consistency between 0 and 0.5foot , firm between 0.5 and 1.1 foot, very firm and containing a clay binder below 2.0 feet. This stratum was underlain by very firm slightly silty fine to medium sand between 5.0 and 11.0 feet, very firm micaceous fine sand between 11.0 and 16.0 feet, very firm fine to medium sand between 16.0 and 20.9 feet, very firm clayey siltstone between 20.9 and 22.0 feet, very firm silty fine sand with occasional lenses of siltstone and clayey siltstone between 22.0 and 41.0 feet, the bottom of the excavation. Free ground water was encountered at approximately 20.7 feet, however it was apparently perched water on top of the clayey siltstone formation because the soil below this level was not saturated. Boring No. 4 Silty fine to medium sand was encountered to a depth of 6.0 feet which was loose in consistency between 0 and 0.7 foot, firm between 0.7 and 1.3 feet and very firm below 1.3 feet. This was underlain by very firm slightly silty fine to medium sand between 6.0 and 9.5 feet, merging to very firm fine to medium sand between 9.5 and 16.5 feet, very firm silty fine sand between 16.5 and 41.0 feet, the bottom of the exploration. Occasional lenses of slightly silty fine to medium sand occurred around 25 feet. Free ground water occurred between 16.0 and 16.5 feet, however it was apparently perched water because the soil below this level was not saturated. The free ground water table is estimated to be at 35.5 feet; however, the surrounding soil is very damp and somewhat imper- vious and it is difficult to establish with certainty that this water level had stabilized. 2. Power Plant Area Boring No. 5 Very firm fine to medium sand with a slight clay binder was encountered to a depth of 3.0 feet, underlain by very firm lean very fine sandy clay between 3.0 and 7.5 feet, very firm BENTON LNGIN£LRIIMG, INC. - -7-' siltstone between 7.5 and 8.0 feet/ very firm fine to medium sand between 8.0 and 8.9 feet/ very firm siltstone between 8.9 and 11.2 feet and very firm very fine sandy clay between 11.2 and 20.9 with occasional lenses of clayey fine to medium sand between 12.5 and 15.5 feet and becoming lean between 19.5 and 20.9 feet. This is further underlain by very firm cemented claystone between 20.9 and 21.5 feet/ very firm very fine sandy clay between 21.5 and 23.7 feet/ very firm claystone 23.7 and 24.0 feet and then very compact fine to medium sand between 24.0 feet and 81.0 feet. The stratum from 24.0 and 81.0 feet contained some lenses of siltstone between 27.0 and 30.5 feet occasional and merging lenses of slightly silty fine to medium sand around 31.0 feet/ sandstone lenses and lime cemented sandstone lenses between 41.8 and 74.5 feet and occasional lenses of slightly silty fine to medium sand between 74.5 and 81.0 feet. This was underlain by very compact fine to medium sand alternating layers of sandstone between 81.0 and 93.0 feet, the bottom of the exploration. Free ground water was encountered at 15.5 feet which is at Elevation 2.2 feet. Boring No. 6 Man-made filled ground was encountered to a depth of 1.7 feet consisting of medium loose silty fine to medium sand and slightly silty fine to medium sand between 0 and 0.6 foot/ underlain by firm silty clay between 0.6 and 1.7 feet. The natural ground consisted of very firm cemented slightly silty fine to medium sand between 1.7 feet and 7.0 feet/ interbedded layers of compact lightly cemented fine to medium sand and slightly silty fine to medium sand between 7.0 to 14.0 feet/ very compact/ slightly clayey fine to medium sand and fine to medium sand with some gravel to 1/2 inch between 14.0 and 18.5 feet/ very firm/ gravelly/ clayey/ fine to medium sand containing 20 percent gravel and cobbles to 5 inches between 18.5 and 20.5 feetand very firm/ slightly silty fine to medium sand with a slight clay binder between*20.5 and 24.0 feet. Very firm/ very lean very fine sandy clay was found between 24.0 and 28.0 feet with some lenses of silty clay between 27.0 and 28.0 feet. Very firm clayey siltstone was found between 28.0 and 28.5 feet. Very firm very fine sandy clay was encountered between BENTON ENGINEERING. INC. " -8-' 28.5 and 30.0 feet and merged to very firm clayey very fine to fine sand and between 30.0 and 37.5 feet, that in turn merged to very firm silty very fine sand between 37.5 and 43.0 feet. A very firm silty clay was found between 43.0 and 44.5 feet with a lime cemented zone of silty fine to medium sand at 44.0 to 44.5 feet, then very firm, silty very fine to fine sand with some medium grains was found between 44.5 and 54.0 feet with lenses of very fine sandy silt between 50.5 and 54.0 feet. A very compact fine to medium sand was found between 54.0 and 75.0 feet with occasional fragments of claystone around 62.0 feet. A very firm lightly cemented slightly silty fine to medium sand was found between 75.0 and 81.0 feet and very compact, lightly cemented fine to medium sand with some coarse grains, and occasional alternating layers of slightly silty fine to medium sand were found between 81.0 and 93.0 feet, the limit of the exploration. Free ground water was encountered at 33.7 feet which is al Elevation +0.7 foot. CONCLUSIONS AND RECOMMENDATIONS Fuel Oil Storage Structures It is concluded from the results of the field investigation and the laboratory testing that: (1) The existing natural soils located below 12 feet below existing grade in the area of the proposed Fuel Oil Storage Structures will provide excellent support for these structures. (2) Calculations, based on the results of the shear tests performed on undisturbed natural soils in the zone of the tank foundations below depths of 12 feet at all of the borings in this area, give a safe allowable bearing pressure of 4000 pounds per square foot for footings founded at least one foot below the lowest adjacent undisturbed natural ground surface. (3) Computations, based on the results of the load consolidation tests,indicate estimated settlements at the middle of each of these storage tanks founded at 15 feet below the present ground surface to be on the order of 1/2 inch. Since the weight of the soils removed from the BENTON ENGINEERING, INC. " -9-' excavation of the Fuel Oil Reservoirs is approximately equal to the loading which will be imposed by the oil tanks, no long term consolidation is anticipated in this area. (4) All of the soils to be excavated may be satisfactorily compacted in fill areas. Although no structural compacted fill is indicated in the project as presented, it is understood that the excess soil derived from excavations will be placed as earth embankment material for protective dikes around the Oil Storage Tanks and in another area on the Encina Plant Site. It is recommended-that these fill soils be compacted in accordance with the recommendations for placement of filled ground, attached hereto as Appendix AA, entitled "Standard Specifica- tions for Placement of Compacted Filled Ground. " Depending on the anticipated use of the new fill areas, either 90 or 95 percent of maximum dry density may be chosen as the compaction standard for these soils. (5) The results of the laboratory expansion test indicates the silty claystone encountered in Boring No. 1 at a depth of 31 feet would be considered as marginally expansive soil. If excavation exposes this expansive soil and if this soil stratum is allowed to remain within the upper three feet below finished grade, it is recommended that footings and slabs of any structure or building to be built thereon be especially designed to reduce the effect of the potential expansion. (6) Cut slopes of up to 30 feet in height in the area of the Fuel Oil Storage Facilities will have a factor of safety of at least 1.5 when constructed at a slope of 1 1/2 horizontal to 1 vertical or flatter. A stability analysis for the above cut slope is presented on Drawing No. 27. The above conclusions assume that proper drainage and erosion control will be provided to prevent surface water from running over the top of the exposed slopes. (7) Since possible fuel spills will have to be contained in the excavation for the fuel storage reservoirs and also ground water and rain water will have to be disposed of from these areas it is concluded that a compacted lining at least 1 1/2 feet in thickness overlaying a gravel BENTON ENGINEERING. INC. ' -]Qt-\*f -..«»•'. drain which extends under the tank and around the excavation into a drain tile collector would adequately serve both purposes. It is recommended that the section of impervious soil layer be placed on and compacted on a slope no steeper than 2 horizontal to 1 vertical. At the time of construction, a satisfactorily impervious clay type soil can be identified from the excavation for this use 0 Power House Unit No, 4 It is concluded from the field investigation and laboratory test results that: (1) The existing natural soils at the elevation of the proposed foundations will provide an excellent foundation material for the support of the proposed structure. (2) Calculations^ based on the results of shear tests performed on the undisturbed natural soils indicate a safe allowable bearing pressure up to 10,000 pounds per square foot for foundations founded at least 5 feet below the undisturbed natural ground surface. (3) Similar to the soil excavated from the Fuel Oil Storage Area, these soils may be satisfactorily compacted in the fill areas in accordance with the attached Appendix AA. (4) Cut slopes up to 70 feet in height will have a factor of safety of 1,5 or greater when constructed on a slope of 1 1/2 horizontal to 1 vertical, or flatter. It is recommended that a horizontal bench at least eight feet in width be constructed at approximately 20 feet above the bottom of the slope „ This bench should be pitched to the cut bank and be sloped to drain to either or both ends of the overall slope where the water would be discharged into some form of protected discharge structure,, A stability analysis for the above cut slope is presented on Drawing No0 28 „ The above conclusions assume that proper drainage and erosion control will be provided to prevent surface water from running over the top of the exposed slope „ For both the slope stability analyses a horizontal seismic force of 0.1 g was applied. BENTON ENGINEERING. INC. (5) It is recommended that retaining walls be backfilled with a granular nonexpansive sand, slightly silty sand, or silty sand, or other suitable material compacted to 90 percent of maximum dry density, and be provided with some means of positive drainage in order to prevent possible hydrostatic pressures from developing behind the walls,, The walls may then be designed using an equivalent fluid pressure of 30 pounds per cubic foot. For soils below the water level, the combined soil and water would exert an active lateral pressure equivalent to 80 pounds per cubic foot. If the soil is to be retained by an inflexible structure such as a basement wall an additional uniform pressure of 100 pounds per square foot should be added to the above described equivalent hydrostatic pressure. (6) Above the water level, an allowable passive soil pressure of 700 pounds per square foot may be used at a depth of one foot below the surface of the undisturbed natural soils below 12 feet below the existing ground at all boring locations. This value may be increased at the rate of 400 pounds per square foot for each additional foot of depth below one foot. If part or all of the soil mass supporting a structure is below the highest anticipated ground water level, the allowable passive soil pressure for that portion below the water level may be increased at the rate1 of 300 pounds per square foot for each foot of depth vice the 400 pounds per square foot presented above for soil occurring above the highest anticipated ground water level. A safe friction factor of 0,45 times the dead load may be applied to resist lateral movement for footings cast directly against the undisturbed natural soils. (7) Calculations, based on the results of the consolidation tests, indicate an estimated settlementof 1/2 inch for a rigid foundation such as that anticipated for the Power House Unit No. 4, loaded to 3000 pounds per square foot. It is anticipated that this entire settlement will take place during construction. BENTON ENGINEERING, INC. ' -12- \t <#• */• Construction Inasmuch as Unit No. 4 will be founded approximately 10 feet below the existing Unit No. 3, some special precautions will be required to protect the existing units during construction of the new, seismically independent Unit No. 4. Initially, dewatering of the area of new con- struction must be accomplished by pumping or other satisfactory measures. After the water level is lowered, one possible method of accomplishing the underpinning would be to excavate a section 10 feet in width down vertically 12 to 18 inches back of the face of the south side of the existing foundation. A reinforced concrete wall could then be cast under this existing founda- tion and north of the south face so that no part of the wall extended to the zone to be occupied by the proposed Unit No. 4. The connection space below the existing foundation and above the proposed wall could be dry packed with an expanding grout such as that produced by Embeco, to provide a founda- tion that would not permit settlement of the existing structure. As an alternative, the expanding grout could be used in the casting of this wall. To further assure stability of the existing structure, pipe nipples could be cast in the proposed wall and a thin slurry of cement and water pumped through these pipes to positively fill any voids remaining behind this section of wall. After this was completed another ten-foot section could be opened and the procedure repeated. If this method of protecting the existing structure is adopted, it is recommended that no more than 25 percent (one ten-foot section out of 40 feet) be excavated at any one time. The remaining portion of the excavation that has not been underpinned by the new wall should not be excavated any deeper than the bottom of the existing foundations during this phase. If this method of pro- tecting the existing structure is adopted, more detailed recommendations as to procedure will be provided upon request. BENTON ENGINEERING, INC. v Since the existing ground water is above the level of the proposed foundation excavation, dewatering will be necessary prior to and during construction. It is understood that dewatering was accomplished for the first stage of construction through excavation of sumps. It would appear that the water bearing strata are porous enough to respond readily to the use of a few shallow wells for the proposed construction. Some experimental work may be necessary during construction to establish the most economical number and configuration of wells for dewatering. It is recommended that the uplift effect of the ground water be taken into consideration in designing the structures including the inlet/outlet channel which, it is understood, will be at approximately Elevation -21 feet. In order to avoid interference in the soil stresses between adjacent foundations, it is recommended that foundations be spaced horizontally and vertically such that a line drawn from the lower adjacent edges of any 2 footings is not steeper than a slope of 1 vertical to 1 horizontal. Wherever foundations are required to be placed closer than the spacing described above, it is recommended that vertical retaining walls be designed to confine the soil supporting the upper foundations. If footings are to be placed closer to exposed slopes than 5 feet inside the top of the ground slopes, these footings should be deepened one foot below a 1 1/2 horizontal to 1 vertical line projected outward and downward from a point 5 feet horizontally inside the top of these slopes. Close inspection of the excavation for Power Plant Unit No. 4 is recommended in order to determine if any soil formations are exposed that differ from those encountered and tested for this investigation. If any soil types are encountered during the excavation or grading operation which are not described in this investigation, additional laboratory tests and engineering analyses should be conducted in order to determine their physical characteristics and supplemental reports and recommendations will automatically be a part of this investigation. BENTON ENGINEERING, INC. t"; •>••' '- i"'--•• •••- -.»-.;•,. _•_- ' ^>'^<r^ 1 -M*- Drawings 1 to 28, inclusive, and Appendices AA, A and B are a part of this report. Respectfully submitted, BENTON ENGINEERING, INC. William G. Catlin, Civil Engineer Reviewe Philip H. Benton, Civil Engineer Distr; (1) San Diego Gas & Electric Company Attention: Mr. C. E. May, Senior Engineer (3X Pioneer Service & Engineering Company (3) Air Mail Attention: Mr. Stanley Gil (1) Sm Diego Gas & Electric Company Attention: Mr. C. Hjalmarson (1) Sjn Diego Gas & Electric Company Attention: Mr. John Burton BENTON ENGINEERING. INC. Tuesday, February 10,1976 The Blade-Tribune—11 Carlsbad May Lose Three Encina Monitoring Stations ByGILDAVIIS Staff Writer CARLSBAD — Carlsbad will lose three monitoring stations for its Encina Power Plant unless the Air Pollution Control District gets more funds. Budget hearings for the county air pollution agency are expected in two weeks. At that time, county supervisors will be asked to accept or reject the three monitoring stations which have been offered by San Diego Gas and Electric Company. The utility has already delivered a check for $81,040 to the APCD. But APDC director William Simmons recently told .Carlsbad League of Women Voters members that the county may not be able to keep the money. Asked about this statement Monday, Simmons replied, "What I said was, 'If I can't operate them, we'll have to give the money back.'" He explained that the APCD had planned on staffing increases. But the day before he spoke to the Carlsbad women, his requests had been cut back. "If several things happen, we can operate those stations," he said. "But we have to get the (computer) hardware so we can reduce the data by computer rather than by hand." Simmons may be able to obtain the $5,000 computer memory device from SDG&E, he indicated. Also needed is more manpower to maintain and repair the sensitive instruments. However, the newly hired APCD director thought he could "squeak by" with present personnel. The monitors were offered by SDG&E over a year ago but never installed because the APCD said it didn't have the funds to adequately utilize the instruments. The three monitors again came to light in November when the state- coastal commission approved a fifth generating unit for the Encina Power Plant. One of the conditions was that SDG&E provide funds to the APCD for purchase of the air quality instrumentation before beginning construction. SDG&E has apparently met this requirement with the $81,040 check. Simmons said the monitering devices would not only be helpful for "keeping track" of the Encina Power Plant, but' would help verify computerized "modeling" which is now based on laboratory tests. Modeling is important because it tries to predict how pollution will disperse once it is emitted by a source. If the forecast shows the pollution emissions are too high, owners of thp source could be required to spend millions of dollars to reduce or better disperse the chemicals. APCD modeling studies show the Carlsbad power plant could presently exceed legal air pollution limits under very unusual weather conditions. But the pockets of high pollution are expected to be very small, said APCD enforcement director Dick Baldwin. Simmons said the APCD is lacking information on air pollution around the county's stationary sources and particularly around the Encina Power Plant. The monitors would also provide background information for the Macario Independent Refinery project. Simmons said the APCD's budgetary problems extend to other areas. A request for three monitoring stations has already been cut from next year's budget. One of the $65,000 devices was scheduled to be situated in Solana Beach or Del Mar. "We hope to get one additional meteorologist who will help us analyze our sources much better than we do now," he said. "A metorologist is really the cornerstone of our program — without another one it will really hamstring our capabilities." /VO I 6 5 /./taoo/v TV "tK.5 • , . ;' •) 'f S »\ fs BOP ' NG c, D/£OO COM PAN? / " = 3 _/~ /-/ • o' 70 4- 28 BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS -— FOUNDATIONS 6741 EL CAJON BOULEVARD SAN DIEGO. CALIFORNIA 92115 PHILIP HENKING BENTON ADDCMPMV D SAN DIEGO: 583-5654 PRESIDENT - CIVIL ENGINEER ArrtrNLMA D LA MESA: 469-5654 Sampling The undisturbed soil samples are obtained by forcing a special sampling tube into the undisturbed soils at the bottom of the boring, at frequent intervals below the ground surface. The sampling tube consists of a steel barrel 3.0 inches outside diameter, with a special cut- ting tip on one end and a double ball valve on the other, and with a lining of twelve thin brass rings, each one inch long by 2 .42 inches inside diameter. The sampler, connected too twelve inch long waste barrel, is either pushed or driven approximately 18 inches into the soil and a six inch section of the center portion of the sample is taken for laboratory tests, the soil being still confined in the brass rings, after extraction from the sampler tube. The samples are taken to the laboratory in close fitting waterproof containers in order to retain the field mois- ture until completion of the tests. The driving energy is calculated as the average energy in foot-kips required to force the sampling tube through one foot of soil at the depth at which the sample is obtained. Shear Tests The shear tests are run using a direct shear machine of the strain control type in which the rate of deformation is approximately 0.05 inch per minute. The machine is so designed that the tests are made without removing the samples from the brass liner rings in which they are se- cured. Each sample is sheared under a normal load equivalent to the weight of the soil above the point of sampling . In some instances, samples are sheared under various normal loads in order to obtain the internal angle of friction and cohesion . Where considered necessary, samples are saturated and drained before shearing in order to simulate extreme field moisture conditions. Consolidation Tests The apparatus used for the consolidation tests is designed to receive one of the one inch high rings of soil as it comes from the field. Loads are applied in several increments to the upper surface of the test specimen and the resulting deformations are recorded at selected time intervals for each increment. Generally, each increment of load is maintained on the sample until the rate of deformation is equal to or less than 1/10000 inch per hour. Porous stones are placed in contact with the top and bottom of each specimen to permit the ready addition or release of water, Expansion Tests One inch high samples confined in the brass rings are permitted to air dry at 105°F for at least 48 hours prior to placing into the expansion apparatus. A unit load of 500 pounds per square foot is then applied to the upper porous stone in contact with the top of each sample. Water is permitted to contact both the top and bottom of each sample through porous stones. Continuous observations are made until downward movement stops. The dial reading is recorded and expansion is recorded until the rate of upward movement is less than 1/10000 inch per hour. BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS FOUNDATIONS PHILIP HENKING BENTON PRESIDENT - CIVIL ENGINEER 6741 EL CAJON BOULEVARD SAN DIEGO. CALIFORNIA 92115 July 24, 1970 San Diego Gas & Electric Company P.O. Box 1831 San Diego/California 92112 Attention: Subject: Mr. C. E. May, Senior Engineer Project No. 70-4-28A Supplemental Design Data San Diego Gas & Electric Company Encina Power Plant Unit No. 4 Carlsbad, California SAN DIEGO: 583-5654 LA MESA: 469-5654 Gentlemen: At the request of Mr. S. P. Gil of Pioneer Service & Engineering Company, the static and dynamic moduli of subgrade reaction have been developed. The results of the computations yield static and dynamic moduli of vertical subgrade reaction to be in excess of 3000 tons per cubic foot for the natural soils located in the formation immediately underlying the foundation of the proposed Power Plant Unit No. 4. However, Dr. Karl Terzaghi in his paper "Evaluation of Coefficients of Subgrade Reaction", sets forth a maximum modulus (Ksj) of 1000 tons per cubic foot for square plates 1 foot by 1 foot for beams 1 foot wide. Therefore, the value of 1000 tons per cubic foot is recommended for use in the above described strata. For a beam with a width of B feet or for a mat acted upon by line loads spaced B feet, the actual modulus of subgrade reaction Ks is determined by the equation: B+l 2 Ks = Please note that the*e values are for the soils as they exist in their present state. Precautions should be taken during construction to prevent ground water from being permitted to flow upward through these soils within the foundation area. If upward water flow occurs or other actions disturb deeper portions of the foundation strata and reduce their densities, this could change the value of the parameters recommended herein. Respectfully submitted, BENTON ENGINEERING, INC. By William G. CatTin, OviTEngineer Distr: (3) Mr. S. P. Gil (1) Mr. C. Hjalmarson (1) Mr. John Burton •-J.-S ui 10 O z >— Ula. £UlO f>— u— . 2- 3- 4- 5- 6- 7- 8- 9- 10- 111— 10U 13- 14- 15- 16- 17- _i ina. • «*i "SUMMARY SHEET BORING NO. ] ELEVATION 44 02' * /^v^ Brown, Dry, Loose /£Xri 7^/** $£?~jf* * r" *S» •.'*f:£':y ""^•'"••'•^•ji 4^ •f *jfm-*y>m $&M t:-fc-'t. ¥''£ f§ /••/Is&ft\r&'$$$> jf *j^^^*/t •/ $& Very Rrm Light Gray-brown, Moist, Very Firm, Cemented, to Depth of 4.0 Feet Some Gravel to 2 Inches Light Gray, Moist, Very Firm, Lean Light Gray, Moist, Very Firm SILTYFINE TO MEDIUM SAND SLIGHTLY SILTYFINE TO MEDIUM SAND CLAYEY FINE TO MEDIUM SAND (Merges) SILTY FINE TO MEDIUM SAND V 0 K•t U. Z v»UJ ft. UJ ^ S UL O 4.8 • 8 1^ 27.6 UJ H-' uj ui gji = 00 11.5 -21. 5n 14.7 it 5 3 Of (D Q -1 111.9 J02.9- 114.7 u£at Z •«0 Ul h- I/I UJ 5;at ^ 1.05 .2.60- 5.06 Continued on Drawing No. 3 (^J) - Indicates Undisturbed Drive Sample * - Indicated elevation in feet at each boring location as provided by the San Diego Gas & Electric Company. PROJECT NO. | DRAWING NO. 70-4-28A BENTON ENGINEERING, INC. 2 t z h- HIa. u.inO I/ " 18- 19- 20- 21- 22- 23- 24- 25- 26- 27- 28- • 29- 30- 31- 33- 34- 35- SSa. a ^f^ >* T/* .*AvOi^yt^ *jr*(*y AC/*yy XY% &Ax&%•Asy< %&:fy£ $%( y\7*&X #%(^*Z».y$&a®•>^y* ' *y*#AXV W%& Tfc f s j/ /f *\s/ / j y>^l/* s A f \f S '••:s~-s-\ 'SUMMARY SHEET / BORING NO 1 (Cont.) Light Gray, Moist, Very Firm Some Lenses of Silty Clay Merging Lime Cemented Sandstone Gray, Moist, Very Firm Continued on Dra SILTY FINE TO MEDIUM SAND (Merges) SILTY CLAYSTONE wing No. 4 at tUJ -^ uj a. > at ^>O 30.8 32.5 36.7 48.3 ui;eg => LU </> (XZQO ** 13.3 14.1 22.7 -22 .7- ll 0 * 117.4 116-8 101.7 -105.0 SHEAR nSISTANCES/SQ. FT. 1UJ _at * 4.62 3.72 *0.97 1 *V?1 «<tT~ * Indicates normal load reduced for anticipated excavation of 25 feet. PROJECT NO. DRAWING NO. 70-4-28A BENTON ENGINEERING, INC. 3 a O z zjjj Ul O —35- 36- 37- 38- 39- 40- 41- 42- 43- 44- 45- 46- 47- 48- 49- 50- 51- 52-SAMPLE INUMBER I*3£p W# ,/j.v/^vX ;?:.• x.'. vtj£':# ^£ * *f * * f *£ * 't'jf • • Ijftgf WB **• *• * * • £ft fjl y* * • *j* * >^ 'i • •¥* r**j ?$& *" * *v* * *^ ^| !^/"HV* V? *.'£•'••$ ^ »*•**• ^> ;>^:^ ^SUMMARY SHEET BORING NO._UCont.) ELEVATION Light Gray, Moist, Very Rrm Occasional Layers of Slightly Silly Fine Sand Thin Lens of Silty Very Fine Sand, Marginal Silt 53_W.sl Continued on Drawing SLIGHTLY SILTY FINE TO MEDIUM SAND £ "-' hu ^> ^ S u.a 26.7 33.3 35.9 70.2 lit Ul UE 5 Q 19.5 13.3 15.5 15.1 j| 105.8 115 6 111.7 115.5 SHEARRESISTANCEKIPS/SQ. FT.3.87 4.6*1 3.60 5.59 No. 5 * Indicates normal load reduced for anticipated excavation of 25 feet. PROJECT NO. DRAWING NO. 70-4-28A BENTON ENGINEERING, INC. 4 COo UJ K_J UI&. fl O ^2 ^-53- 54- 55- 56- 57- CQ— ('••.:?:;••#00 ->:--y.-.-- 59- 60 v SUMMARY SHEET BORING NO._U£pnt.) Light Gray, Moist, Very Firm SLIGHTLY SILTYFINE TO MEDIUM SAND DRIVE ENERGYFT. KIPS/FT.uu {•K 3603_J h- >-ui in £f E 5 o S-4 UI !_'u£a(Z •«O^ 1U k- <AT- I «A ^v 2 ^2^at 5 i . PROJECT NO. 70-4-28A BENTON ENGINEERING, INC. DRAWING NO. 5 • .<-#<KS* ? t SI L. A •••i LL LU <»3 0 0 «/> Ul5< ce C , ' z xt££IU O ., .MM rtU 1- 2- 3— 4- 5_ 6 — -T_ /^ 8- 9- 10- 11- 12- 13- 14- 15- 16- 17 18- 19-SAMPLE 1NUMBER 1*y*y*/ '$&i/'X*/\ * *• r*« *.*• •,' 1 V.i::-:.-::i .•.•.•.•.•/•;.; Ill HI •:;•....:':'.•':• •;'•';'•''•'.• '•'•'• ** **•**•**$i Brown v SUMMARY SHEET BORING NO._^ ELEVATION 47.4' , Dry, Loose Mofst, Rrm Very Firm Light Gray-brown, Mofst, Compact, Micaceous With Layers of Fine Sand \ Free Water, (Perched) \ Saturated Light Gray, Moist, Very Firm PROJECT NO. 70-4-28A Continued on Drawing SILTYFINE TO MEDIUM SAND (Merges) FINE TO MEDIUM SAND / SILTYFINE SAND No. 7 DRIVE ENERGY 1FT. KIPS/FT, j19.5 8.1 9.7 35.4 FIELD 1MOISTURE 16 8 6 11 BENTON ENGINEERING, INC. t^ ata s« 0 2 9 .9 iflis* 115.5 99.4 99.4 120.2 r SHEAR HI RESISTANCE| KIPS/SQ. FT. |1.46 1.34 1.70 4.49 DRAWING NO. 6 COo z Ulo 20- 21- 22- 23- 24- 25- 26- 97Li 98— 29-J 30- 31- 32- 33- 34- 35- 36-SAMPLENUMBER$$ $v YVn/y ^Vr»'y/ /[ /vVA/V/v ' 'A/,t/y f/y.my\/\y Y. // yjC $r \/j/\ /J/Y yf >i A s\ W SUMMARY SHEET BORING NO. 2 (Cont.) Light Gray, Moist, Very Firm Lime Cemented Sandstone SILTYFINE SAND AND ALTERNATING LAYERS AND LENSES OF SOME SILTSTONE AND CLAYEY SILTSTONE DRIVE ENERGY!FT. KIPS/FT, j30.9 60.0 37.5 60.0 Ul t~ * iQ 3 -!»->•ui \n & uT 5 Q 5S« 21.9 12.7 24.0 12.6 ui R° -> i S 105.0 116.2 101.0 113.0 SHEAR 1RESISTANCEKIPS/SQ. FT. 16.39 0.40 3.96* *1.62 ! I * Indicates normal load reduced for anticipated excavation of 25 feet. PROJECT NO. DRAWING NO. 70-4-28A BENTON ENGINEERING, INC. 7 1 1>1 z • ilL Ul0 1- . 0 - 3- 4- 6- 7- 8- 9- 10- 1 11 1 12- 13- 14- 15- 17- 18- 19- 20-SAMPLE 1NUMBER 1«^§ ^$f$mi iv/vv.'^ /'S*— ^.*v« '.* • • v *"v\ X/'.\^v/X""yv-'y"*"1 *.;:/*::>*v: r •*;!*•' •*."•* :•;.;;;.';.•}: ii '*";•".".•• •"• * *•*•*•"•* • * • • •:.:.-::'.'-V-: .. •...•. •• B •*•"•"•"•*•**•"i *• * * * i •»"•** ^SUMMARY SHEET BORING NO 3 FIPVATION 56.6' Brown, Dry, Loose Moist,•Firm. Very Firm Clay Binder Light Gray-brown and Yellow- Brown, Moist, Very Firm Gray-brown, Moist, Very Firm, Micaceous Gray-brown, Moist, Very Firm Continued on Dra PROJECT NO. 70-4-28A SILTYFINE TO MEDIUM SAND SLIGHTLY SILTYFINE TO MEDIUM SAND FINE SAND FINE TO MEDIUM SAND wire No. 9 DRIVE ENERGYFT. KIPS/FT.11.4 8.1 11.4 32.5 in tat <a 3-J t- >-Ul t/» (x = O ° ** 9.1 6.9 4.0 9.4 >• IA _ 123.1 104.1 98.1 114.5 SHEAR 1RESISTANCEKIPS/SQ. FT. |1.52 1.54 2.45 4.19 1 DRAWING NO. BENTON ENGINEERING, INC. 8 t ZL UlO SAMPLENUMBER\ SUMMARY SHEET BORING NO.__3_l£ont.) Gray-brown, Moist, Very Firm Free Water (Perched) Saturated Gray, Moist, Very Firm Light Gray, Moist, Very Firm, _,!....•.•;:.-• With Occasional Lenses of '•"•"•"•• Siltstone and Clayey Siltstone 25-T." 26-mt 27-- 28-J 29- \ 30-£ SILTYFINE 31-4^:^ SAND 32 33-K 34-:| 35-: : *-jK 37- ij 38- ji 39-^ 40-ii FINE TO MEDIUM SAND CLAYEY SILTSTONE DRIVE ENERGY30.8 50.0 45.5 60.0 54.5 FIELDMOISTURE% DRY WT12.8 EARTANCESHESIS111.0 11.6 121.1 13.8 13.7 12.5 113.9 116.8 117.3 CEFT.RKIPS4.47 2.40 2.94 2.94 * Indicates normal load reduced for anticipated excavation of 25 feet. PROJECT NO. 70-4-28A BENTON ENGINEERING, INC. DRAWING NO. 9 ea O z _ t-Sffift. u.uiO - 0" il — 2- 3- 4- 5- - 7- 8- o_ 10- n- M 12- 13- 14- 15- 16- 17 18- " 19- 20- a! tt|S $T* Vvy ^§ CuZv3^ *,{ V/7y ^% ^i^£'&& ^":j^:l> ^§1 f/^V^ y^Y^'^f#•:•?:•£ *•***.** •*.*• "•-,*.*•"•*• /fS-- ••^v^-'.V • • * •".."' •."••*..•.. ,^XV/ $# ^4^ty*/* v SUMMARY SHEET BORING NO 4 PIEVATION 49.4' Brown, Dry, Loose \ ^Moist, Rrm Very Firm Brown, Moist, Very Firm Light Brown, Moist, Very Firm Free Water (Perched) \Saturated Light Gray, Moist, Very Rrm "* SILTY FINE TO MEDIUM SAND (Merges) SLIGHTLY SILTY FINE TO MEDIUM SAND (Merges Clean) PIMF TO MPHII IAArllNC 1 v iV\ClxlU/V\ SAND / SILTY FINE SAND o ^K iii £ & O Ul »-" Q 3->>->•Ul V% K E Q Q ^ 16.2 8.1 9.7 - 30.8 >• Z -j UJ Jj QC «o -1 7.2 ^120.0 5.2 5.6 99.5 95.8 ! u£ K Z • UJ t- «/> 5s£Ul _ K X. 2.33 1.57 1.77 13.8 117.12.81 1 i PROJECT NO. DRAWING NO. 70-4-28A BENTON ENGINEERING, INC. 10 t CDo 24- SUMMARY SHEET BORING NO. 4(Cont.) Light Gray, Moist, Very Firm Occasional Lenses of Slightly Si try Fine to Medium Sand 32- 34- 35- Saturated 41-? SILTY FINE SAND o Z <£Uj CL. Ul Z> H.- _ IU l/ts 5 >- K , *~ £2 -• 35.2 3.27 57.1 12.5:115.2 1.11 54.4 54.4 13.3 113.9 12.3 2.70 115.1 3.25 60.0 5.7 111.0 3.60 Indicates normal load reduced for anticipated excavation of 25 feet. PROJECT NO. 70-4-28A BENTON ENGINEERING, INC. DRAWING NO. 11 01 O Z H. UJ Q 2 ^ 4- 5- 6- 7- 9— 10- 11- 12- 13- * 14-. 15- 16- 17- 18-1 SAMPLE 1NUMBER 1• '.** -••."*" '.V.vXyX' ***••*••!•• •.';::';•:)'•'. ••'••'•'•'{•'•': •'.•.'•'•'.•'.'•'.•'.: sis v?yl••''.•'•'•':'• •'/•'••••':':'•'• m **•'"'• i ••'•• . • . .•_•-.. "SUMMARY SHEET BORING NO. 5 PlfVATION 17-7', Gray, Moist, Very Firm, Slight Clay Binder Gray, Moist, Very Firm, Lean Gray, Moist, Very Rrm Gray, Moist, Very Firm Gray, Moist, Very Rrm Gray, Moist, Very Firm With Occasional Lenses of Clayey Fine to Medium Sand Saturated Continued on Dra FINE TO MEDIUM SAND VERY FINE SANDY CLAY SILTSTONE FINE TO MEDIUM SAND SILTSTONE VERY FINE SANDY CLAY wing No. 13 DRIVE ENERGYFT. KIPS/FT.40.6 24.3 42.2 ui tat i 03_!(->-UJ «/1 of >E O ° *t* 11.1 8.8 12.7 UJ 2O \ i 3 115.4 116.2 120.0 I SHEARRESISTANCEi KIPS/SQ. FT.7.40 4.79 4.96 s 1 I PROJECT NO. DRAWING NO. 70-4-28A BENTON ENGINEERING, INC. 12 I ? i 8 1 X *~ •' h» ui : O, |LUl0 in 19- 20- 22- 23- 24- 25- 26- 27- 28- 29- 30- 31- 32- 33- 34- 35- 36- 37-SAMPLE 1NUMBER 1?®5 .1 ' V — ' -L,— L, s^isKJ>^i 'i^"r>.» «M^^j • '/•';:'-:.:/.V- '.*-*.*• • • • *. &:•'•'.•.'•'•'••.'•• '•'.* *.* ','••' il i'. **'•'.''• B * In SUMMARY SHEET BORING NO. 5(Cont.) Gray, Saturated, Very Firm Lean Brown, Saturated, Very Rrm, \ Cemented Gray, Brown, Moist, Very Firm JJrown, Moist, Very Firm Gray, Saturated, Very Compact Some Lenses of Si Its tone Occasional and Merging Lenses of Slightly Silry Rne to Medium Sand Continued on Drawing dicates normal load reduced for anl VERY FINE SANDY CLAY CLAYSTONE VERY FINE SANDY CLAY CLAYSTONE FINE TO MEDIUM SAND 3 No. 14 Hcipated excavation [ DRIVE ENERGY1 FT. KIPS/FT.26.0 40.6 60.0 54.5 54.5 99.9 75.0 of 32 ! FIELD 1i MOISTURE23. $ atO i* 3 17.3 8.8 16.8 13.5 NOS 19.5 feet al PROJECT NO. 70-4-28A BENTON ENGINEERING, INC. i t 99.7 113.1 123.0 113.2 119.5 »AMPL 107.9 > this 1 SHEARRESISTANCEKIPS/SQ. FT.6.24 4.56 3.59 E 0.33 ocatio 1 i 1t 1 \ 1 i n. DRAWING NO. 13 : i ' i»i z xth- UJas*o 17O/ 38- 39- 40- 41- 42- A1*rO 44- 45- 46- 47- 48- 49- 50- 51- 52- 53- 54- 55- 56-SAMPLE 1NUMBER 1:::;'.••:';/';• •.'•'•'."•'.'•'. 3@£; :/•'••' •':••.'•: ill^iii} '•'•:.::':::-'- '.'.••'.'.•'•'.'• '. •;*.'•'• ' .' •'.* '•'•:'•: '•:'••.'• '•'.'•';•'.'•'•'•.'•' Si v :'•'.:'• V-\: .. .;. •.*.'.; •.'•.'•"••'•':•."•'. I::;;:':':.;;- '••.'•:•.•.-:•': •.'•.'•: :.':::.'-: ' • * '* '• *•.'".*«" "'.'•"-."•.*/."• ".•."•*•*;•*• 3J^S :J.:::\-V.';.;. ^SUMMARY SHEET BORING NO.__5_CCpnt.) Gray, Saturated, Very Compact Lime Cemented Sandstone Lens, 2 Inches Thick Lime Cemented Sandstone Lens, 6 Inches Thick Occasional Sandstone Lenses Lime Cemented Sandstone Lens, 6 Inches Thick Many Thin Lenses of Sandstone Continued on Drawir * Indicates normal load reduced f< location . FINE TO MEDIUM SAND g No. 15 JT anticipated excavc I DRIVE ENERGY1 FT. KIPS/FT.60.0 133.3 114.1 151.0 jtion c PROJECT NO. 70-4 -28A BENTON ENGINEERING, INC. m£" £03*_1 t- >-ui in IK E O ° ** 18.7 9.9 14.4 14.9 f32f( |E 1 | >• "j S 2 111.1 129.2 118.0 115.0 set at DRA SHEARRESISTANCEKIPS/SQ. FT.1.05* 1.43 2.86 this ! # t ( •* | I \ i WING NO 14 LU * ^03 O z xS££UJ cc— -3D 57- 58- 59- 60- 61 - 62- 64- !} « ji 66- 68- 69- 70- 71- 72- ujjg II Vv.v.'.v-!'' '•"•".'. '. '• • ; ' •'.""".'•'•.'• •' gj V-V :-'- ''.':'•'. ': .".• ' '•'.'•'•'•'•.*/.'. ••'.•.'•'•'•'••' HI g '•"••.' •'. • • '•'•'•'•:'•••'•:: !•.'••.':'•••'•'•.'•: •'?•':'::•':.'•': Hi * •''*•/.'.' • '•'•:'•' •:'••':• '•'•;••;•'•. :•:'•'.''••'.•'. •••:•:'.':• : • • .- •., > ,* • ^SUMMARY SHEET ^ BORING NO._KCont.) Gray, Saturated, Very Compact, WiJh Sandstone Lenses Sandstone Lens 3 Inches Thick Lime Cemented Sandstone, 10 Inches Thick Some Coarse Grains With Some Sandstone Lenses Continued on Drawinj * Indicates normal load reduced location. FINE TO MEDIUM SAND 3 No. 16 :or anticipated excav DRIVE ENERGY 1FT. KIPS/FT. 1151.0 162.4 162.4 198.0 ation ku in ix 15. 14 14 8 8 .8 13.8 of 321 PROJECT NO. 70-4-28A BENTQN ENGINEERING, INC. ^"* ^L ^U ^m g s 115.5 117.1 114.5 119.2 reet at SHEARRESISTANCEKIPS/SQ. FT.1.70 4.9§ 4.2J 3.90 this DRAWING NO. 15 £ ca O Z is UJO -»i/O 74- 75- 76~ 77- 78- 79- 80- 81 82- 83- 84- 85- 86- 87- 88- 89- 90- 91- 92-SAMPLENUMBER''''*''••' "•"• *"•"»' *.' •'•'.••/.•••'.•. • •'•;.'••'•':' •':V-'-il:-: .':•••'.•'.'. .'•.'.•"•.'•*,* '•'.•'.•'•'•'•, 1 .*.*•*.'*•"•*.*' '.'."•"• •••..•*••' '.*'*'•'.*•*.',*•' $3i••••••••.** S! &$£ •'.• *.'.* .'• ,», ••V.V//-V ^ SUMMARY SHEET BORING NO. _5(Cont.) Gray, Saturated, Very Compact, With Sandstone Lenses Occasional Lens of Slightly Silty Fine to Medium Sand Gray, Saturated, Very Compact FINE TO MEDIUM SAND FINE TO MEDIUM SAND WITH ALTERNATING LAYERS OF SANDSTONE •DRIVE ENERGYFT. KIPS/FT.209.1 209.1 272.8 181.0 ^t* £as"-j t~ >•uj in at E 5 Q «i? 12.7 14.1 15.5 10.8 >- 2 S 2 121.7 117.8 117.3 124.6 CO SHEAR^ RESISTANCEoo * KIPS/SQ. FT.4.48* 4.10 7.50 } •- \ * Indicates normal load reduced for anticipated excavation of 32 feet at this location. PROJECT NO. DRAWING NO 70-4-28A BENTON ENGINEERING, INC. 16 •£o E i £ g 'i LU •J J q Q in Ul1 Z. a> 0 Z Xt ££Ul O . S 1- 2- 3- 4- 5- 6- 7/ 8- 9- 10- 11- 12- 13- 1 if. ..14 15- 16- 17-SAMPLE 1NUMBER 1&ti$, & Pi '/£:$$.. '•*'••* *.'•*•' P ^"•'fe^;Xv^ 1 '.•.•;:'.'."•:: SUMMARY SHEET BORING NO. 6 ELEVATION 34.4' Red-brown and Light Brown, i Slightly Moist, Medium Loose \ Gray, Moist, Rrm Red-brown, Slightly Moist, Very Firm, Cemented Light Red-brown and Light Yellow brown, Slightly Moist, Compact, Lightly Cemented / Brownish-gray and Red-brown, Moist, Very Compact, Some Gravel to 1/2 Inch Continued on Drawir PROJECT NO. 70-4-28A SILTY FINE TO MEDIUM SAND J AND SLIGHTLY / SILTY FINE TO /, \MEDIUMSAND // \SILTYCLAY / SLIGHTLY SILTY FINE TO MEDIUM SAND INTERBEDDED LAYERS OF FINE TO MEDIUM SAND AND SLIGHTLY SILTY FINE TO MEDIUM SAND (Irregular Contact) SLIGHTLY CLAYEY FINE TO MEDIUM SAND AND FINE TO MEDIUM SAND ^ No. 18 DRIVE ENERGYFT. KIPS/FT... 22.7 6.5 14.6 BENTON ENGINEERING, INC.FIELDMOISTURE% DRY WT. 13.3 4.5 6.2 \l 103.5 100.9 112.9 DRA 1 SHEARRESISTANCEKIPS/SQ. FT.2.94 0.89 3.41 WING 1 7 i !i '*! I I "i QD O t- UJO. li.UlO S—17- 18- 19- 20- 21- 22- 23- 24- 25- 26- 27- 28- 29- 30- 31- 32- 33- 34- 35- 36- -I Ula. an SUMMARY SHEET BORING NO 6 (O?pt.) Brownish-gray and Red-brown, Moist, Very Compact, Some Gravel to 1/2 Inch Olive-gray and Red-brown, Moist, Very Firm, 20 Percent Gravel and Cobbles to 5 Inches Light Olive-gray, Moist, Very Firm, Slight Clay Binder Gray, Moist, Very Firm, Very Lean Lenses of Silty Clay 'ray, Moist, Very Firm Gray, Moist, Very Firm Gray, Moist, Very Firm Water, -T-VT^ Saturated, Gray With Red-brown Streab [ | - Indicates Loose Bag Sample SLIGHTLY CLAYEY FINE TO MEDIUM SAND AND FINE TO MEDIUM SAND GRAVELLY CLAYEY FINE TO MEDIUM SAND SLIGHTLY SILTY FINE TO MEDIUM SAND VERY FINE SANDY CLAY ZLAYEYSILTSTONE VERY FINE SANDY CLAY (Merges) CLAYEY VERY FINE TO FINE SAND Continued on Drawing No. 19 PROJECT NO, 70-4-28A BfcMTON ENGINEERING, INC. • .. •*- ~"-' VTJ^* 4 ffiQ 38- 47-» 48- 49- 55-1 SUMMARY SHEET f BORING NO 6_{Cfint.) Gray With Red-brown Streaks, Saturated, Very Firm Gray, Saturated, Very Firm Olive-gray, Saturated, Very Firm, With Lime Cemented Zone of Silty Fine to Medium k Sand at 44.0 to 44.5 Feet Olive-gray, Saturated, Very Firm, Some Medium Grain, Cemented CLAYEY VERY FINE TO FINE SAND (Merges) SILTY VERY FINE SAND SILTY CLAY Lenses of Very Fine Sandy Silt SILTY VERY FINE TO FINE SAND Gray, Saturated, Very Compact Continued on Drawing No. 20 FINE TO MEDIUM SAND a at < 2R>.Ul I/I Kz 5 ° *,! 13 50.0 14.0 117.0 53.3 12.3118.6 ui M' z1"28»A *~-. S?« x 6.17 5.10 114.1 15.1 114.7 7.50 88.4 13.8 112.5 5.24 i I 158.5 16.6 112.8! 0.93 84.2 14.0117.31.81 * Indicates normal load reduced for anticipated excavation of 48 feet. PROJECT NO. 70-4-28A BENTON ENGINEERING, INC. OKAWING HO. 19 tz SUMMARY SHEET BORING Gray, Saturated, Very 57-:•£&$ Occasional Fragments of FINE TO MEDIUM 14.3 118.4 16.1 115.3 Continued on Drawing No. 21 * Indicates normal load reduced for anticipated excavation of 48 feet. PROJECT NO. 70-4-28A BENTOM ENGINEERING, INC. DRAWING NO 20 z x£ UlQ -TA/4 — 75/ J 76- 77- 78- 79- 80- 82- | 83- 84- 85- 86- 87- 88- 89- 90- 9h 92-SAMPLE 1NUMBER 1'.'.'•.'•_•'•'•.'. % a • \^-'.'/^ ':• v>V--V-" Sf••*•• • • *, ' '.:••'•': '•:••'• z## Si *.'•*.".• •*.* *. •"•"."*•* * ** ' • ':'••'•; ::•':: ':••'•::•''•':'.' • -'.\.- •:':[: •22v'- ' ^SUMMARY SHEET BORING NO._6_XCflnt.) Gray, Saturated, Very Compact Light Gray-brown, Saturated, Very Firm, Lightly Cemented Light Gray, Saturated, Very Compact, Some Coarse Grains, With Occasional Alternating Layers of Slightly Silty Fine to Medium Sand, Lightly Cemented FINE TO MEDIUM SAND (Merges) SLIGHTLY SILTY FINE TO MEDIUM SAND FINE TO MEDIUM SAND DRIVE ENERGr!FT. KIPS/FT, j205.0 318.0 482.0 492.0 £*'03_!!->-ui in K E O Q Si« 13.4 13.7 13.4 16.3 II >- ui 121.4 118.8 121.0 114.3 SHEARRESISTANCEKIPS/SQ. FT. 12.2*5 3.7*2 3.8*1 3.82 i * Indicates normal load reduced for anticipated excavation of 48 feet. PROJECT NO. 70-4-28A BENTON ENGINEERING, INC. DRAWING NO 21 O *O UJ odS O• Q IS) BO CONSOLIDATION PERCENT OF SAMPLE THICKNESSH- + -t- If- + + -f- t-(0 — O — NJ CO hO — . O — • hO GJ 4^9 ' — ^ 1 — ___ ' ^ -.v "1 CONSOLIDATION CURVES LOAD IN KIPS PER SQUARE FOOT 0.4 0.6 0.8 1.0 2 4 6 8 10 16 ~ —- . -— ~^^>*--. ' ~-~ -— - — ---. —- ~~_ — , ^ -^ ^^ -— --. "N -- -- - — • V \ —- - -— .. \^ ^•- \ ~~~-^ ^-— x ^~~^ ^^ \\ — __ \ \ ^ Bori Sam Dep \, ng 1 pie 7 Hi 31' + Boring 1 Sample 7 Depth 3 1 ' 0 INDICATES PERCENT CONSOLIDATION AT FIELD MOISTURE • INDICATES PERCENT CONSOLIDATION AFTtft SATURATION PROJECT NO. 70-4-28A BENTON ENGINEERING, INC. DRAWING NO. 22 0 § f2 ,L H io 1 8 S 2 0 0.4 CONSOLIDATION CURVES LOAD IN KIPS PER SQUARE FOOT 0.6 0.8 1.0 2 4 Boring 4 SampTe 7 Depth 31' _8 10 Boring 2 Sample 7 Depth 31' Boring 3 Sample 5 Depth 21 Boring 5 Sample 9 Depth 36' O INDICATES PERCENT CONSOLIDATION AT FIELD MOISTURE • INDICATES PERCENT CONSOLIDATION AFTER SATURATION PROJECT NO. 70-4-28A BENTON ENGINEERING, INC. DRAWING NO. 23 • -• •' Ul * 09, 1 i 2 < 3 A CONSOLIDATION PERCENT OF SAMPLE THICKNESSe*> ro — o ro — ' o••> ' ' :'"1 CONSOLIDATION CURVES LOAD IN KIPS PER SQUARE FOOT 2 0.4 0.6 0.8 1.0 2 4 6 8 10 16 1 • . — - — - . .. lx— — - — — 1 - - - - ~ — . — - — .. — —~ . -•-•- k - •• — -. *a=as; —- --- =--=: "— — — - —- ~ ~J H -*H ~— < ^-^_ ^, ~~~-— " ' •< ^^-^ • ^-^.. ^=^S __ 1 — N— — . ^i^ ' — — 1 » — — - — . -•— . Boring 5 Sample 15 Depth 63' ^^~ ^ Boring 6 Sample 12 Depth 53' Soring 6 Sample 15 Depth 62' i <^ p^. 0 INDICATES PERCENT CONSOLIDATION AT FIELD MOISTURE • INDICATES PERCENT CONSOLIDATION AFTER SATURATION PROJECT NO. 70-4-28A BENTON ENGINEERING, INC. i • DRAWING NO. 24 . i . .,, . m.u>a I *?•f. *| i A '** f 4 < f V T* 1 '-I < £ ^ %f* ;,J «3 6 • Q tX u CONSOLIDATION PERCENT OF SAMPLE THICKNESS•N CO K5 — . O- - O2 ' . '- --^ 1 _ » _ __ V * y> »,•} CONSOLIDATION CURVES LOAD IN KIPS PER SQUARE FOOT 0.4 0.6 0.8 1.0 2 4 6 8 10 16 ' • ==-..-; . — • - — — — ~ — — — — •— . t— — — — — — ..-., — ^. =r i— i 1 — — - • _ — ""i*- 0 INDICATES • INDICATES PROJECT NO. 70-4-28A MB= ' — ^ > — __ . — _: — -• - - - 1 _ — — < __ ^ • ) ~~ . ^^ 1 -J — ' ' . . ^-^ •~ _ *• — - -~~^ - — ~- ~ ^-- — trr=»». i— — — Boring 5 Sample 12 J?enth 46' ^^ \, Boring 6 Sample 12 Depth 53' — ~<^~ —^^ PERCENT CONSOLIDATION AT FIELD MOISTURE PERCENT CONSOLIDATION AFTER SATURATION BENTON ENGINEERING, INC. DRAWING NO. 25 _ _ ,_-, *$ ***^ ; » « 5 •5, *1 ^;; A 1, J^ 9 s, -J i ^ ^ -1 41 " I*;ji Boring No. 5 Sample 7 Depth =? 29.0 feet Sample 8 Depth =32.0 feet Sample 10 Depth = 39.0 feet tf =38.9° 'C =16P.sJ. =2300PSF 120 100 80\j OV/ • ^I 60 40 20. ... \~ - - 1. .„ ^ ^ - It / 11 - /f ; /f 1^ / / & /]lf/\ >/ -• 1 <^/ f 4 i 7 ? s•* / •*- A •** L-, $* / \ / S ^ > .s ^ •* \ f -"• \\ / \ s * \I / ~*\ f •**. s / -- £ s 1^ - ^s j- / "** \V / •^ - - ~ri— ~tl-J .._ - - / " X ^J -*-t - - - - 7* ,-.-- .... - - _ 7 — E ~t~ -t"hr "r- - r '- sh~ _ .... - - ._ ... s ... _ S - I ._ "j~ ~ _ — s — - f \ --J r - N .... ... : \ — — „ _ - & ._- - i — h - ... E 20 40 60 80 100 120 140 160 180 - - ~ r _ - - - - - _ - j h | -t~J - - - - — _ L 4-1 $ ~ - - _ ... -- — ... — — - 200 220 TRIAXIAL COMPRESSION TEST RESULTS SAN DIEGO GAS & ELECTRIC COMPANY ENCINA POWER PLANT CARLSBAD, CALIFORNIA PROJECT NO 70-4-28A BENTON ENGINEERING,INC. DRAWING NO. 26 SLOPE STABILITY ANALYSIS. SAN DIEGO GAS & ELECTRIC COMPANY ENCINA POWER PLANT CARLSBAD, CALIFORNIA PROJECT NO. 7O- 4-2&A DRAWING NO 27BiNTON gNGlNEERING, INC. ^ VNi * 5 N 0 0N ty SLOPE STABILITY ANALYSIS ENCINA POWER PLANT SAN DIEGO GAS & ELECTRIC COMPANY » w KN x * PROJECT NO. 70-4-28A BENTON ENGINEERING, INC. DRAWING NO. 28 BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS -—- FOUNDATIONS 6741 EL CAJON BOULEVARD SAN DIEGO, CALIFORNIA 82115 PHILIP HENKING BENTON SAN DlEGO: 583-5654 PRESIDENT - CIVIL ENGINEER LA MESA: 469-5654 APPENDIX AA STANDARD SPECIFICATIONS FOR PLACEMENT OF COMPACTED FILLED GROUND 1. General Description. The objective is to obtain uniformity and adequate internal strength in filled ground by proven engineering procedures and tests so that the proposed structures may be safely supported. The procedures include the clearing and grubbing, removal of existing structures, preparation of land to be filled, filling of the land, the spreading, and compaction of the filled areas to conform with the lines, grades, and slopes as shown on the accepted plans. The owner shall employ a qualified soils engineer to inspect and test the filled ground as placed to verify the uniformity of compaction of filled ground to the specified 90 percent of maximum dry density. The soils engineer shall advise the owner and grading contractor immediately if any unsatisfactory conditions are observed to exist and shall have the authority to reject the compacted filled ground until such time that corrective measures are taken necessary to comply with the specifications. It shall be the sole responsibility of the grading contractor to achieve the specified degree of compaction. 2. Clearing, Grubbing, and Preparing Areas to be Filled. (a) All brush, vegetation and any rubbish shall be removed, piled, and burned or other- wise disposed of so as to leave the areas to be filled free of vegetation and debris. Any soft, swampy or otherwise unsuitable areas shall be corrected by draining or removal, or both. (b) The natural ground which is determined to be satisfactory for the support of the filled ground shall then be plowed or scarified to a depth of at least six inches (6"), and until the surface is free from ruts, hummocks, or other uneven features which would tend to prevent uniform compaction by the equipment to be used. (c) Where fills are made on hillsides or exposed slope areas, greater than 10 percent, horizontal benches shall be cut into firm undisturbed natural ground in order to pro- vide both lateral and vertical stability. This is to provide a horizontal base so that each layer is placed and compacted on a horizontal plane. The initial bench at the toe of the fill shall be at least 10 feet in width on firm undisturbed natural ground at the elevation of the toe stake placed at the natural angle of repose or design slope. The soils engineer shall determine the width and frequency of all succeeding benches which will vary with the soil conditions and the steepness of slope. APPENDIX AA _ 2 - (d) After the natural ground has been prepared, It shall then be brought to the propsr mois- ture content and compacted to not less than ninety percent of maximum density fn accordance with A.S.T.M. D-1557-66T method that uses 25 blows of a 10 pound hammer falling from 18 inches on each of 5 layers in a 4" diameter cylindrical mold of a l/30th cubic foot volume. 3. Materials and Special Requirements . The fill soils shall consist of select materials so graded that at least 40 percent of the material passes a No. 4 sieve. This may be obtained from the excavation of banks, borrow pits of any ofher approved sources and by mixing soils from one or more sources. The material uses shall be free from vegetable matter, and other de- leterious substances, and shall not contain rocks or lumps of greater than 6 inches in diameter. If excessive vegetation, rocks, or soils with inadequate strength or other unacceptable physical characteristics are encountered, these shall be disposed of in waste areas as shown on the plans or as directed by the soils engineer. If during grading operations, soils not encountered and tested in the preliminary investigation are found, tests on these soils shall be performed to determine their physical characteristics. Any special treatment recommended in the preliminary or subsequent soil reports not covered herein shall become an addendum to these specifications. The testing and specifications for the compaction of subgrade,subbase, and base materials for roads, streets, highways, or other public property or rights-of-way shall be in accordance with those of the governmental agency having jurisdiction. 4. Placing, Spreading, and Compacting Fill Materials. (a) The suitable fill material shall be placed in layers which, when compacted shall not exceed six inches (6"). Each layer shall be spread evenly and shall be throughly mixed during the spreading to insure uniformity of material and moisture in each layer. (b) When ihe moisture content of the fill material is below that specified by the soils engineer, water shall be added until the moisture content is near optimum as specified by the soils engineer to assure thorough bonding during the compacting process. (c) When the moisture content of the fill material is above that specified by the soils engineer, the fill material shall be aerated by blading and scarifying or other satis- factory methods until the moisture content is near optimum as specified by ihe soils engineer. (d) After each layer has been placed, mixed and spread evenly, it shall be thoroughly compacted to not less than ninety percent of maximum density in accordance with A.S.T.M. D-1557-66T modified as described In 2 (d) above. Compaction shall be accomplished with sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other approved types of compaction equipment, such as vibratory equipment that is specially designed for certain soil types. Rollers shall be of such design that they will be able BENTON ENGINEERING. INC. APPENDIX AA - 3 - to compact the fill material to the specified density. Rolling shall be accomplished while the fill material is at the specified moisture content. Rolling of each layer shall be continuous over its entire area and the roller shall make sufficient trips to insure that the desired density has been obtained. The entire areas to be filled shall be compacted . (e) Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compacting operations shall be continued until the slopes are stable but not too dense for planting and until there is no appreciable amount of loose soil on the slopes. Compacting of the slopes shall be accomplished by backrolling the slopes in increments of 3 to 5 feet in elevation gain or by other methods producing satisfactory results. (f) Field density tests shall betaken by the soils engineer for approximately each foot in elevation gain after compaction, but not to exceed two feet in vertical height between tests. Field density tests may be taken at intervals of 6 inches in elevation gain if required by the soils engineer. The location of the tests in plan shall be so spaced to give the best possible coverage and shall be taken no farther apart than 100 feet. Tests shall be taken on corner and terrace lots for each two feet in elevation gain. The soils engineer may take additional tests as considered necessary to check on the uniformity of compaction. Where sheepsfoot rollers are used, the tests shall be taken in the com- pacted material below ffie disturbed surface. No additional layers of fill shall be spread until the field density tests indicate that the specified density has been obtained. (g) The fill operation shall be continued in six inch (6") compacted layers, as specified above, until the fill has been brought to the finished slopes and grades as shown on the accepted plans. 5. Inspection. Sufficient inspection by the soils engineer shall be maintained during the filling and compacting operations so that he can certify that the fill was constructed in accordance with the accepted specifications, 6. Seasonal Limits. No fill material shall be placed, spread, or rolled if weather conditions increase the moisture content above permissible limits. When the work is interrupted by rain, fill operations shall not be resumed until field tests by the soils engineer indicate that the moisture content and density of the fill are as previously specified. 7. Limiting Values of Nonexpansive Soils. Those soils that expand 2.5 percent or less from air dry to saturation under a unit load of 500 pounds per square foot are considered to be nonexpansive. 8. All recommendations presented in the "Conclusions" section of the attached report are a part of these specifications. BENTON ENGINEERING, INC. • > BENTON ENGINEERING, INC. APPLIED SOIL MECHANICS FOUNDATIONS 6741 EL CAJON BOULEVARD SAN DIEGO. CALIFORNIA 92115 PHILIP HENKING BENTON PRESIDENT - CIVIL ENGINEER SOIL DESCRIPTION APPENDIX A Unified Soil Classification Chart* SAN DlEGO: 583-5654 LA MESA: 469-5654 GROUP TYPICAL SYMBOL NAMES I. COARSE GRAINED More than half of material is larger than No. 200 sieve size.** GRAVELS CLEAN GRAVELS More than half of coarse fraction is larger than No. 4 sieve size but smaller GRAVELS WITH FINES than 3 inches SANDS More than half of coarse fraction is smaller than No. 4 sieve size (Appreciable amount of fines) CLEAN SANDS SANDS WITH FINES (Appreciable amount of fines) II. FINE GRAINED, More than half of material is smaller than No. 200 sieve size.'SILTS AND CLAYS Liquid Limit Less than 50 SILTS AND CLAYS Liquid Limit Greater than 50 III. HIGHLY ORGANIC SOILS GW Well graded gravels, gravel-sand mixtures, little or no fines. GP Poorly graded gravels, gravel-sand mixtures, little or no fines. GM Silty gravels, poorly graded gravel- sand-silt mixtures. GC Clayey gravels, poorly graded gravel- sand-clay mixtures. SW Well graded sand, gravelly sands, little or no fines. SP Poorly graded sands, gravelly sands, little or no fines. SM Silty sands, poorly graded sand-silt mixtures. SC Clayey sands, poorly graded sand-clay mixtures. ML Inorganic silts and very fine sands, rock flour, sandy silt or clayey-silt-sand mixtures with slight plasticity. CL Inorganic clays of low to medium plas- ticity, gravelly clays, sandy clays, siJty clays, lean clays. OL Organic silts and organic silty-clays of low plasticity. MH Inorganic silts, micaceous or diatoma- ceous fine sandy or silty soils, elastic silts, CH Inorganic clays of high plasticity, fat clays. OH Organic clays of medium to high plasticity. PT Peat and other highly organic soils. * Adopted by the Corps of Engineers and Bureau of Reclamation in January, 1952. ** All sieve sizes on this chart are U0S. Standard.