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Home My WebLink About; Reclaimed Water Storage Reservoir No. 1; Soils Report; 1979-09-01Woodward.Clyde Consultants DESIGN MEMORANDUM GEOLOGIC STUDY, GEOTECHNICAL ENGINEERING, AND DESIGN SERVICES FOR RECLAIMED WATER STORAGE RESERVOIR NO. 1 LA COSTA, CALIFORNIA Woodward-Clyde Consultants DESIGN MEMORANDUM GEOLOGIC STUDY, GEOTECHNICAL ENGINEERING, AND DESIGN SERVICES FOR RECLAIMED WATER STORAGE RESERVOIR NO. 1 LA COSTA, CALIFORNIA SAN MARCOS COUNTY WATER DISTRICT RECLAMATION PROJECT For La Costa Land Company Carlsbad, California September 1979 WOODWARD-CLYDE CONSULTANTS Consulting Engineers, Geologists, and Environmental Scientists WoodwarxbClyde Consultants PREFACE This Design Memorandum is one of five documents comprising the bid package for the construction of two dams (Storage Reservoir No. 1 and Balancing Reservoir) in connection with the San Marcos County Water District Reclamation Project. The five documents are: (1) (2) (3) (4) (5) Plans for Storage Reservoir No. 1 Design Memorandum for Storage Reservoir No. 1 in two parts: Part 1 - Site Investigations and Laboratory Testing Part 2 - Design of Dam, Spillway, and Outlet Works Plans for Balancing Reservoir Design Memorandum for Balancing Reservoir in two parts: Part 1 - Site Investigations and Laboratory Testing Part 2 - Design of Dam, Spillway, and Outlet Works Specifications ii Project No. 59185V-DSOl Woodward-Clyde Consultants TABLE OF CONTENTS TITLE PAGE PREFACE LIST OF FIGURES ACKNOWLEDGEMENTS INTRODUCTION DESCRIPTION OF THE STORAGE RESERVOIR PROJECT PREVIOUS STUDY SCOPE OF THIS STUDY Page i ii vi viii 1 2 3 3 PART 1 - SITE INVESTIGATIONS AND LABORATORY TESTING 1.1 INTRODUCTION 1.2 PHYSIOGRAPHY 1.3 FIELD EXPLORATION 5 5 1.3.1 Test Borings, Pits, and Trenches 5 1.3.2 Classification of Material 7 1.3.3 Pressure Tests 8 1.4 GEOLOGY 1.4.1 Geologic Units 1.4.1.1 Topsoil 1.4.1.2 Alluvium 1.4.1.3 Tertiary Age Sedimentary Rock 9 10 10 10 1.4.1.4 Jurassic Age Santiago Peak Volcanics 11 1.4.2 Rock Fractures and Shears 1.4.3 Rock Permeability 1.5 SEISMICITY AND REGIONAL TECTONIC SETTING 13 13 1.5.1 General 14 1.5.2 Distant Faults 16 1.5.3 Local Faults 17 1.5.3.1 Rose Canyon Fault Zone 17 iii Project No. 59185V-DSOl Woodward.Clyde Consultants TABLE OF'CONTENTS (Can't) Page 1.6 SEISMICITY 1.6.1 Regional Seismicity (Onshore) 1.6.2 Regional Seismicity (Offshore) 1.6.3 Local Seismicity 1.6.4 Shaking Intensity 18 19 19 22 1.7 SOURCES OF MATERIALS 1.7.1 Impervious Material 22 1.7.2 Embankment Shell Material 24 1.7.3 Drain and Filter Material 25 1.8 FOUNDATION CONDITIONS 1.8.1 Degree of Weathering 25 1.8.2 Dam Foundation Preparation 26 1.8.3 Foundation Seepage 27 1.8.4 Spillway Foundation Conditions 27 1.8.5 Foundation Condition of Inlet-Outlet Works 28 1.9 LABORATORY TESTS AND MATERIAL PROPERTIES 29 1.9.1 Embankment Shell Materials 29 1.9.2 Impervious Core Materials 1.9.2.1 Classification Tests 31 1.9.2.2 Compaction Tests 31 1.9.2.3 Strength Tests 1.9.2.4 Permeability Tests 3": 1.9.2.5 Solubility Tests 33 1.9.2.6 Suitability of Fine-Grained Soils 34 1.9.3 Filter Materials 35 1.9.4 Riprap 36 1.9.5 Analysis 36 TABLE I - REPORT OF WATER PRESSURE TEST TABLE II - SUElMARY OF CREDIBLE AND PROBABLE EVENTS PART 2 - DESIGN OF DAM, SPILLWAY, AND OUTLET WORKS 2.1 EMBANKMENT DESIGN 2.1.1 General Features of the Embankment 2.1.2 Embankment Geometry iv 37 38 Project No. 59185V-DSOl Woodward-Clyde Consultants TABLE OF CONTENTS ( 2.1.3 Seepage Control Features 2.1.4 Embankment and Excavation 2.1.5 Freeboard 2.1.6 Upstream Slope Protection Can't) Quantities 2.2 SEEPAGE 2.2.1 Seepage through the Embankment 2.2.2 Seepage through the Foundation 2.2.3 Porewater Pressure Distribution - Steady Seepage Condition 2.2.4 Drawdown Condition 44 46 47 47 2.3 INSTRUMENTATION 2.3.1 Piezometers 2.3.2 Deformation Monitoring Monuments 2.4 STABILITY ANALYSIS 2.5 SPILLWAY 2.5.1 Hydrology 2.5.2 General Criteria 2.5.3 Spillway Details 47 48 48 53 55 56 2.6 OUTLET WORKS 2.6.1 Operation 2.6.2 Outlet Conduit 2.6.3 Intake Structure 58 59 60 2.6.3.1 Intake Structure Sluice Gate 62 2.6.4 Outlet Structure 63 2.6.4.1 Outlet Sump System 64 2.6.4.2 Sump 65 2.6.4.3 Pump System 67 2.6.4.4 Valves 69 2.6.4.5 Flanges and Pipe 70 2.6.4.6 Miscellaneous 70 REFERENCES BIBLIOGRAPHY GLOSSARY V Page 40 41 41 43 Project No. 59185V-DSOl WoodwardGlyde Consultants LIST OF FIGURES Number 1.1 1.2 1.3 1.4-1.13 1.14 1.15-1.16 1.17 1.18 1.19-1.22 1.23-1.24 1.25-1.44 1.45 1.46-1.52 1.53 1.54 2.1 2.2 2.3 2.4 2.5 PART 1 TYPICAL FIELD PERMEABILITY INSTALLATION DETAILED SAN DIEGO FAULT MAP EARTHQUAKE EPICENTERS IN SAN DIEGO AREA GRAIN SIZE DISTRIBUTION CURVES KEY TO LOGS LOG OF AXIAL TRENCH LOG OF TRENCH 1 - SOUTH WALL LOG OF TRENCH 1 - NORTH WALL LOGS OF TEST PITS LOGS OF TEST TRENCHES LOGS OF TEST PITS KEY TO CORE BORING LOGS BORING LOGS FILL SUITABILITY TESTS SLOW DIRECT SHEAR TEST PART 2 FLOW NET FOR STEADY SEEPAGE - FULL RESERVOIR FLO\? NET FOR STEADY SEEPAGE - FULL RESERVOIR FLOW NET FOR STEADY SEEPAGE - PARTIAL POOL FLOW NET FOR SEEPAGE THROUGH THE FOUNDATION EQUIPRESSURE LINES FOR STEADY SEEPAGE vi Project No. 59185V-DSOl Number 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 Woodward.Clyde Consultants LIST OF FIGURES (Con't) EQUIPRESSURE LINES FOR PARTIAL POOL FLOW NET FOR RAPID DRAWDOWN EQUIPRESSURE LINES FOR RAPID DRAWDOWN UPSTREAM SLOPE STABILITY - FULL RESERVOIR CONDITION DOWNSTREAM SLOPE STABILITY - FULL RESERVOIR CONDITION UPSTREAM SLOPE STABILITY - PARTIAL POOL CONDITION UPSTREAM SLOPE STABILITY - SUDDEN DRAWDOWN CONDITION KEY TO SLOPE STABILITY FIGURES PRECIPITATION STATIONS - SAN DIEGO COUNTY vii Woodward.Clyde Consultants ACKNOWLEDGMENTS Personnel of Woodward-Clyde Consultants most involved in the studies leading up to and in preparing the plans and specifi- cations and design memorandum included: Stanley F. Gizienski, Principal in Charge: James E. Cavallin, Chief Engineer; and Walter Crampton, Project Engineer. Field geology and explorations were done by Daryl Streiff, Charles G. Bemis, Dorian Elder, Marvin Iverson, and David Iverson. Design studies were done by Dr. Iraj Noorany, Carol Forrest, and Buck Buchanan. Graphics were done by Margaret Kelly, Carla Fargo, and Sue Heidrick. Technical typing was done by Verna Paschall, Vicky Moothart, Ruth Seykora, and Linda Mott. The Design Memorandum was edited by Linda Mott for clarity and technical format. viii Project No. 59185V-DSOl Woodward-Clyde Consultants DESIGN MEMORANDUM GEOLOGIC, GEOTECHNICAL ENGINEERING, AND DESIGN SERVICES FOR RECLAIMED WATER STORAGE RESERVOIR NO. 1 LA COSTA, CALIFORNIA INTRODUCTION The San Marco.5 County Water District and Ranch0 La Costa of Carlsbad, California, plan to construct two earth- fill dams in the La Costa development area of Carlsbad, California (Sheet 1 of the plans). One dam (creating the Storage Reservoir) will be constructed just east of Ranch0 Santa Fe Road (NW l/4 Sec. 32, T. 12 S., R. 3 W., S.B.B.M.); the other dam (creating the Balancing Reservoir) will be constructed east of El Fuerte Street (SW l/4 Sec. 30, T. 12 S ., R. 3 W., S.B.B.M.). The function of both reservoirs will be to inter- mittently store varying volumes of treated sewage effluent for spray irrigation. This report records the geologic and geotechnical investigations and design analyses used in preparing plans and specifications for the Storage Reservoir project only. It is furnished as a companion document to the plans and specifications for the project. Project No. 59185V-DSOl Woodward-Clyde Consultants Our study of the Balancing Reservoir,~ which will store only 13.8 acre-ft of water, is presented in another report (Project No. 59185V-DS02). DESCRIPTION OF THE STORAGE RESERVOIR PROJECT The Storage Reservoir dam, a zoned earthfill embankment, measures 80 ft from the downstream toe to dam crest and 76 ft from toe to spillway crest. The dam will be constructed of earth materials available at the site and at an offsite borrow area located about 7,000 ft to the south- west. Graded filter materials and concrete aggregate will be imported from aggregate plants in San Diego County. The reservoir will have a 54-mg design capacity (166 acre-ft) and will be confined in an east-west-trending valley, which has moderately to steeply-sloping sides. An ungated, concrete-lined spillway will be con- structed on the ridge of the right abutment about 350 feet upstream of the right end of the dam. The spillway will discharge under the right abutment access road, through two arch culverts, and into a valley that drains to the north- east. Outlet works, consisting of an intake structure, an outlet conduit, and an outlet structure, will be used for filling the reservoir, discharging water for spray irriga- tion, and emptying the reservoir quickly, if necessary. 2 Project No. 59185V-DSOl Woodward-Clyde Consultants In addition to the dam and reservoir, the total project will include irrigation pipelines, a sewage treat- ment plant, a surface water diversion located above the maximum operating pool of the reservoir, and various access roads. Because the proposed dam and reservoir will serve as temporary storage for treated sewage effluent during the rainy seasons, the reservoir will be empty or at low levels during about nine months of the year. PREVIOUS STUDY A feasibility study for the proposed project was made by our firm in 1978. The report of that study (Project No. 58309V-DSOl) is entitled "Feasibility Study and Pre- liminary Cost Estimate, Reclaimed Water Storage Reservoir No. 1, San Marcos Canyon, La Costa, California," dated September 15, 1978. SCOPE OF THIS STUDY A preliminary report of our studies was submitted to the Division of Safety of Dams, Department of Water Resources, State of California, on August 6, 1979. This is our final report, which serves as the Design Memorandum accompanying the plans and specifications. Project No. 59185V-DS01 Woodward-Clyde Consultants Under an agreement with the La Costa Land Company of Carlsbad, California, Woodward-Clyde Consultants has provided geologic, geoJ.echnical engineering, and design services for the proposed Storage Reservoir, dam, and appurtenances. The geologic and geotechnical investigations consisted of exploring foundation conditions at the spill- way site and dam site, locating suitable construction materials close to the dam embankment, sampling foundation and borrow materials, and making field and laboratory tests. These tests provided data concerning engineering properties and parameters needed to design the structure in accordance with the acceptable standards of practice for earth dams. Our design studies consisted of proportioning the dam, making analyses of seepage and stability, and designing the spillway and the inlet and outlet structures. Finally, plans and specifications were prepared for construction. This report is presented in two parts: Part 1 describes the field explorations, geologic studies, and laboratory tests: Part 2 describes design studies for the dam, spillway, and outlet works. Project No. 59185V-DSOl Woodward-Clyde Consultants PART 1 - SITE INVESTIGATIONS AND LABORATORY TESTING 1.1 INTRODUCTION This section discusses the field and laboratory studies that were made to evaluate the site geology, seis- micity, and geotechnical conditions. 1.2 PHYSIOGRAPHY The Storage Reservoir is to be located at the head end of an unnamed tributary to Encinitas Creek. The dam will be between approximate Elevation 520 ft (MSLD) at the downstream toe, and approximate Elevation 598.5 ft at the crest. The topography on the south shore of the reservoir consists of a north-facing mountain (approximate Elevation 1,046 ft), which has slope inclinations of approximately 2 to 1 (horizontal to vertical). The north side of the reservoir is formed by an east-west, elongated ridge that has south-facing slopes, approximately 5 to 1, and a maximum elevation of 673 ft. A rounded drainage cuts through the site from Elevation 598.5 ft at a saddle at the east end of the proposed reservoir to Elevation 520 ft at the dam toe. The drainage has an average slope of 5-l/2 percent. The proposed emergency spillway is located on the north side of the reservoir (approximately 320 ft east of the dam axis) where present lowest ground elevation is 592 ft. 5 Project No. 59185V-DSOl Woodward-Clyde Consultants The drainage area surrounding the reservoir en- compasses approximately 26 acres, and is covered by low chaparral, which is thicker and denser on the north-facing slopes. A grove of eucalyptus trees is located in the general southeastern portion of the reservoir and the slopes above. Precipitation in the area averages approximately 12 in. per year. Annual variations in precipitation are expected to range from a few inches to about 2 ft per year. Annual evaporation in the area is approximately 55 in. Man-made features on the site consist of explora- tion trenches, access roads, and spoil piles constructed during the subsurface investigation. A dirt road trends along the valley bottom. A small earth dam and pond are present about 500 ft downstream of the proposed dam, and a power transmission line trends east-west north of the pro- posed dam. 1.3 FIELD EXPLORATION 1.3.1 Test Borings, Pits, and Trenches Fifty-three exploratory excavations~ and borings were made at the locations shown on the plans (Sheets 2 Project No. 59185V-DSOl Woodward-Clyde Consultants and 3). Explorations 1 through 11 and 19 through 49, the Axial Trench, and Test Borings S-l, S-la, and S-2 were made to investigate the dam foundation conditions and nearby borrow areas. Trenches 12 through 18 were excavated to obtain information about the offsite borrow area (Sheets 1 and 3 of the plans) for impervious material. The test pits were excavated with various size backhoes, namely John Deere Models 310, 410 and 510. The trenches were dug with a KomatSU 155 dozer and an Inter- national Harvester TD15 dozer. The borings were made with a truck-mounted Mobil B-53 drill rig using a Longyear HQ3 wireline triple tube diamond core barrel. 1.3.2 Classification of Materials Samples of representative subsurface materials were gathered from the trenches and pits for classification and embankment suitability tests. Continuous rock cores were obtained in borings drilled into the rock below the topsoil and completely-weathered rock. The rock cores were examined for quality, degree of soundness, amount of weather- ing, spacing of fractures, and type. For the purpose of uniformity of identification of rocks, the degree of weathering was defined as: Project No. 59185V-DSOl Woodward-Clyde Consultants (a) (b) (c) (d) (e) "Fresh rock" shows no discoloration, loss of strength, or any other effects due to chemical or mechanical weathering. "Slightly-weathered rock" is slightly discolored, but not noticeably weaker than the fresh rock. "Moderately-weathered rock" is discolored and noticeably weathexed, but drilled cores or equal size fragments cannot be broken by applying pres- sure by hand across the rock fabric. "Highly-weathered rock" is discolored and weakened to the degree that drilled cores or equal size fragments can readily be broken by applying pres- sure by hand across the rock fabric. "Completely-weathered rock" is discolored and has entirely changed soil consistency, but the origi- nal rock fabric is nearly preserved. During our field investigation, the degree of rock fracturing was defined as: 0.0 to 4.0 in. - highly fractured 4.0 to 12.0 in. - moderately fractured 12 in. and over - slightly fractured A detailed description of geologic units is found in Section 1.4.1. 1.3.3 Pressure Tests At the completion of Borings S-la and S-2, pres- sure tests were made in the borings to evaluate the relative permeability of the in situ rock. The in situ permeability tests were made using the general procedures outlined in the 8 Project No. 59185V-DSOl Woodward-Clyde Consultants U.S. Bureau of Reclamation's "Earth Manual." Each test boring was drilled to full depth and tested from immediately below the casing to the bottom of the hole (Fig. 1.1). Table I presents the pressure test field data. The pumping test data indicate that the fractures are generally tight within the foundation rock. In addi- tion, drilling fluid losses were very minor, further indi- cating the relatively low permeability of the rock. 1.4 GEOLOGY 1.4.1 Geologic Units Three geologic units were mapped in conjuction with the Storage Reservoir: two units within the dam and reservoir area, and a third unit in an area proposed as an offsite borrow for impervious material. Although soil divisions (topsoil, residual clay, and minor slopewash are not mappable geologic units, they are important considera- tions in design and construction: therefore, soil divisions were explored extensively. The geologic units found on the site are described in order of increasing age: 9 Project No. 59185V-DSOl Woodward-Clyde Consultants 1.4.1.1 Topsoil The topsoil horizon within the dam and reservoir area is composed of material that varies from brown, gravelly, silty, fine sand to red-brown, silty clay. These materials vary from 0 to 2.5 ft thick and are, in general, underlain by a brown, silty, residual clay. A representative section of material was exposed in the Axial Trench; the topsoil unit averaged approximately 1 ft thick, and the residual clay varied from 0 to 4 ft thick. The residual clay unit generally forms a very irregular surface developed on the underlying rock units. A wedge of highly-fractured, angular, clayey, gravel slopewash, which overlies the bedrock unit and interfingers with the alluvium in the valley bottom, occurs below approximate Elevation 532 ft in the trench. 1.4.1.2 Alluvium Alluvial deposits up to 8 ft thick (average thick- ness 4 ft) underlie the dam site within the valley floor. Where observed in trenches and pits, the alluvium is com- posed of brown to light olive-green, gravelly, silty clay. 1.4.1.3 Tertiary Age Sedimentary Rock The offsite impervious borrow area is underlain by rock that has been mapped as belonging to the La Jolla Group 10 Project No. 59185V-DSOI Woodward-Clyde Consultants of Tertiary age sedimentary formations. Portions of this group have been correlated to the Santiago Peak formation of southern Orange County. The similarity of rock type between the two formations makes the units difficult to differentiate. For this report, the La Jolla Group name will be used. At the borrow site, the unit consists of unlithi- fied, interbedded, gray, limonite-stained, fine, sandy silt and maroon to gray, silty clay. Discontinuous gypsum inter- beds and seams up to 1 in. thick were observed at the con- tact of the clay beds with the overlying silt beds, and within the clay beds along planes of parting and fracturing. It is expected that some finely-divided and disseminated gypsum occurs throughout the entire formational unit. The gypsum and other soluble salts were evaluated using a hot and cold distilled water solubility test (Section 1.9.2.5, Solubility Tests). 1.4.1.4 Jurassic Age Santiago Pe,ak Volcanics Metavolcanic and metasedimentary rocks of the Santiago Peak volcanics form the bedrock in the dam and reservoir areas and are the foundation rocks underlying the entire dam. These rocks were deposited during the Jurassic period and later metamorphosed, apparently in conjunction with the emplacement of the Southern California Batholith during the Cretaceous period. 11 Project No. 59185V-DSOl Woodward-Clyde Consultants Exploration trenches exposed metavolcanic rock at the dam axis from Elevation 598.5 to 520.0 ft. Borings in the dam foundation investigated the metavolcanic rock to a depth of 41 ft (Elevation 489 ft) below the valley bottom. Where observed in the pits and borings, the rock varied from a highly-fractured, highly-weathered, brown, siliceous, meta-tuff breccia to a brown, fine-grained, highly-weathered meta-tuff. Interbeds of slightly-weathered and slightly-fractured, dark blue-green, aphanitic, siliceous meta-tuff are present. Zones of meta-lapilli-tuff were encountered throughout the rock section. A faint develop- ment of schistosity trending northeast-southwest was observed in the upper portion of the left abutment. A petrographic examination of one thin section of metavolcanic rock revealed the following: Mineral % ,in Section Chlorite 55 Feldspar 30 Quartz 5 Iron Ore 3 Epidote 2 Hornblend 2 Calcite 2 Sphene 1 Based on the petrographic examination, the rock classifies as a propylitic tuff. 12 Project No. 59185V-DSOl Woodward-Clyde Consultants 1.4.2 Rock Fractures and Shears The Santiago Peak metavolcanic rock unit is highly fractured: fracture spacing is on the order of less than 1 in. to over 1 ft. In general, the fractures dip very steeply (60 to 90 degrees) and have omnidirectional trends. Shear zones were encountered in the Axial Trench. The zones trend northwest to southeast and dip from 50 to 72 degrees south. The zones are highly fractured and hydro- thermally altered. The fractures are tight and filled by highly-plastic, gray-brown clay. A shear zone was also encountered in Trench 10. This zone trends northeast to southwest, dips steeply east, was hydrothermally altered, and has tight, clay-filled fractures. The tightness of the fractures and the presence of highly-plastic clay in the fractures reduces the potential for seepage under the dam; however, possible leakage of impounded water through the abutments needs to be considered. 1.4.3 Rock Permeability Based on the results of pressure tests, we estimate that the permeability of the moderately to highly-weathered rock is very low on a scale of "high," "medium," "low," 13 Project No. 59185V-DSOl Woodward-Clyde Consultants "very low," and "practically impervious." .The permeability is estimated to be 1x10 -6 ft/min for the moderately to highly-weathered rock: 1x10 -5 ft/min for the slightly- weathered rock; and 5x10 -1 ft/min for the fresh rock. 1.5 SEISMICITY AND REGIONAL TECTONIC SETTING 1.5.1 General The seismicity of the area at the Storage Reser- voir is evaluated by assessing the potential for earthquakes in close proximity to the site. One of the most significant aspects in estimating the likelihood of earthquakes is general geological frame- work. The present framework is most easily understood in terms of the theory of plate tectonics. This theory states that the crust of the earth consists of several continental plates and many smaller plates that interact at their edges in ways depending on crustal conditions in the region. According to this theory, California and Baja California sit astride a plate boundary along which interaction is expressed as right lateral and some vertical faulting that produce shallow focus earthquake activity. In the regional view, coastal California and Baja California are moving to the north with respect to inland California and mainland Flexico. 14 Project No. 59185V-DSOl WoodwardGlyde Consultants In Holocene geologic time (last 11,000 years), movement due to this regional process has been centered in Imperial Valley along faults of the San Andreas fault system. These faults fall within a wide band, which is located 23 to 71 miles northeast of the site, and are part of the Elsinore fault zone, San Jacinto fault zone, and San Andreas fault zone. The faults in this system are expressed by one or more of the following characteristics: long, continuous lineaments; dislocation of geologically young sediments; large offsets of older geologic formations; sag depressions: offset stream courses: and sharply-defined fault scarps. The character of faulting in the San Diego region lacks all of the above features, with the possible exception of large offsets of older geologic formations. Within the continental borderland offshore from San Diego, several faults have been postulated, based on topographic lineaments and sub-bottom acoustic profiles that define scarp-like features. The character of the offshore faulting more closely relates to normal faulting in the San Diego area than to the lateral movement of the San Andreas fault system. 15 Project No. 59185V-DSOl Woodward-Clyde Consultants 1.5.2 Distant Faults The nearest known distant (greater than 20 miles) fault along which earthquakes having Richter Magnitudes greater than 4 have been reported is the Elsinore fault zone. The Elsinore fault zone is located approximately 23 miles northeast of the site, and is part of an 8-mile wide band which, for the purpose of this report, includes the Aqua Caliente and Earthquake Valley faults. The estimated maximum credible earthquake for the Elsinore fault zone is magnitude 7-l/2 (Table II). The San Jacinto fault zone is located approxi- mately 46 miles northeast of the site. This zone has greater historic and instrumentally-recorded activity than the Elsinore fault, and has been the site of recent moderate to large earthquakes within Imperial Valley. The estimated maximum credible earthquake for the San Jacinto fault is magnitude 7-3/4. The San Clemente fault zone is located approxi- mately 54 miles west of the site. Some significant seismic activity has been reported along the San Clemente fault zone, which has an estimated maximum credible earthquake of magnitude 7-l/2. 16 Project No. 59185V-DSOl Woodward-Clyde Consultants 1.5.3 Local Faults Faults in the northern San Diego County area within 20 miles of the site are, in general, poorly defined. Where observed, the faults exhibit characteristics that are not indicative of recent movements. The Rose Canyon fault zone, which has been postulated to be offshore west of the dam site, is the only fault that may have exhibited Quaternary movement. 1.5.3.1 Rose Canyon Fault Zone Reference to the Rose Canyon fault appears in geologic literature published prior to 1920. A fault is shown in Rose Canyon on a 1919 Water Supply Paper by Ellis and Lee. The fault on the original map terminated in the vicinity of Pacific Beach; however, since the original mapping, various geologists have extended the fault south- erly; some projecting it through San Diego Bay, others projecting it more easterly so it passes onshore adjacent to the bay. Moore and Kennedy (1975) report that about 1 km of right lateral movement has occurred across the Rose Canyon fault over the past l,OOO,OOO years, resulting in an average slip of 1 m per 1,000 years. Historically, however, the Rose Canyon fault has been noted for its general quiescence. 17 Project No. 59185V-DSOl Woodward-Clyde Consultants Some geologists have concluded that if, in fact, the Rose Canyon fault is a part of the major zone described before, it is locked off and not presently active. In one part of La Jolla, no apparent evidence of displacement in colluvium (Carbon-14 dated to be about 1,000 years old) could be found across what was interpreted to be the main branch of the Rose Canyon fault zone. The closest postulated fault trace of the Rose Canyon fault zone is located approximately 7 miles west of the site (Fig. 1.2). 1.6 SEISMICITY 1.6.1 Regional Seismicity (Onshore) An analysis of the seismicity of the Imperial Valley region was made by McEuen and Pinckney (19721, who developed an earthquake magnitude recurrence curve for a lO,OOO-sq-km area of the region. The major fault zones contained within the Imperial Valley study area, as pre- viously discussed, are the San Andreas, the San Jacinto, and the Elsinore. Historically, the San Jacinto has been the more active of these fault zones. However, since the Elsinore fault zone is closest to the San Diego region and the lengths of the faults are similar, it is assumed that 18 Project No. 59185V-DSOl WoodwatxhClyde Consultants there is an equal probability of a major event occurring within either the San Jacinto or the Elsinore fault zones. Based on this criteria and using the slope of the curve developed by Allen (1965) for the Imperial Valley region, it is estimated that the maximum probable event for the San Jacinto or Elsinore fault zone is between magnitude 7 and 7- 1/4, having a repeat interval on the order of 100 years (McEuen and Pinckney, 1972). 1.6.2 Regional Seismicity (Offshore) The longest fault within the California borderland is the San Clemente fault, which is approximately 100 miles long and 54 miles distant from the site. A maximum credible earthquake of magnitude 7-l/2 would be produced by breakage along this fault. Instrumentally-recorded data in the area are too sparse to assign a meaningful probable event to the San Clemente fault. Since its historically-recorded activity has been less and its distance is greater, it does not appear to be quite as significant a hazard to the San Diego area as is the Elsinore fault zone. 1.6.3 Local Seismicity The San Diego area is considered to be a tectoni- cally stable area because of its low historical seismicity. 19 Project No. 59185V-DSOl Woodward-Clyde Consultants Thirty-seven earthquakes of Richter Magnitude 2.3 to 3.7 were reported between 1934 and 1974 within the greater San Diego area by the California Institute of Technology, Seismological Laboratory (Simmons, 1977a, 197713) (Fig. 1.3). Three of these earthquakes had epicenters within the vicinity of San Diego Bay, and occurred on June 21, June 22, and July 14, 1964, having Richter Magnitudes of 3.7, 3.6, and 3.5, respectively. There are no known active faults in the vicinity of the dam and reservoir with which probable earthquakes can be associated; however, the Rose Canyon fault zone is suggested to be located about 7 miles west of the site, and is postulated to have a length sufficiently long to produce large magnitude earthquakes. The Rose Canyon fault zone could produce credible ~events of approximately magnitude 6-3/4 (McEuen and Pinckney, 1972). It is, therefore, more likely that the Rose Canyon fault zone would be the pos- tulated local source of a large magnitude earthquake, rather than some unknown or lesser fault in the region. Some authors, notably Wiegand, have extended the Rose Canyon fault to the south through San Diego Bay to project and tie into the San Miguel fault in Baja California. Wiegand has also suggested that the fault projected to the north and postulated a tie-in with the Newport-Inglewood 20 Project No. 59185V-DSOl WoodwardXilyde Consultants fault zone. In George W. Moore's paper, "Offshore Extension of the Rose Canyon Fault, San Diego, California," (1) sub- bottom acoustical profiles were analyzed, and it was pos- 'tulated that the Rose Canyon fault zone projects as far north as Camp Pendleton toward the Newport-Inglewood zone. Moore states: "Projection of the zone farther north suggests that the Rose Canyon fault may be related to the Newport- Inglewood fault system; to the south, it may join the San Miguel fault in Baja CaZifornia." It should be noted that the above are merely postulated continuations of the Rose Canyon fault. Historic seismic events have been recorded on the San Miguel fault south in Baja California, as well as along the Newport- Inglewood fault zone; however, no significant seismic activity has been recorded on the Rose Canyon fault. The main fault and some branches of the Rose Canyon fault offset the Pleistocene age Lindavista formation (500,000 to 3,000,OOO years old), but many branches do not. Approximately 450 ft of vertical separation of the base of the Lindavista formation has been recognized near Mount Soledad. The Pleistocene age Bay Point formation (100,000 to 130,000 years old) lies across some branches of the fault, but is not offset. 71 Project No. S918SV-DSOl Woodward-Clyde Consultants 1. 6. 4 Shaking ,Int,en,sity One useful measure of the effect of an earthquake is the maximum or peak acceleration in rock at the site produced by an earthquake. For this report, we have con- servatively assumed that the considered earthquakes will occur at the closest approach of the fault to the site. Using this assumption, along with the charts of acceleration versus distance developed by Idriss (~19781, we have estimated peak bedrock accelerations likely to be felt at the site (Table II). The highest estimated accelerations of 0.2g from a distant event (Elsinore fault zone) are due to a credible earthquake of magnitude 7-l/2. Accelerations from local events could range up to as much as 0.4g for a credible magnitude 6-3/4 event (McEuen and Pinckney, 1972) on the Rose Canyon fault. Again, this earthquake has an excep- tionally small likelihood of occurrence. 1.7 SOURCES OF MATERIALS 1.7.1 Impervious Material Two areas of fine-grained soil were investigated for the dam's impervious zone (Zone 2). The fine-grained materials on the site within the dam foundation preparation 22 Project No. 59185V-DSOl Woodward-Clyde Consultants area, the alluvial soils downstream from the dam, and the topsoil and residual soils northwest of the right abutment could result in approximately 33,000 cu-yd of fine-grained material. Pits revealed that materials useable for the impermeable zone varied from 0.5 to 6 ft thick (average thickness about 2 ft). The material varied from dark-brown, clayey sand to brown, silty clay having occasional fine to medium, angular gravels. An offsite source of fine-grained borrow was investigated in an area east and north of the intersection of La Costa Avenue and Ranch0 Santa Fe Road, approximately 7,000 ft south of the site. This borrow source is composed of interbedded, gray, fine, silty sands; clayey, fine sands: silts: and maroon to gray, silty clay. Within the offsite borrow pit, an area containing approximately 78,000 cu-yd of material was investigated. Pit logs indicate that about 61 percent of the material present in the borrow area consists of clay: approximately 47,000 cu-yd of clay is available for use in the dam. In order to use just clay, selective grading may be necessary. A well-mixed combination of all in-place materials present in the proposed offsite borrow pit appears to be adequate for construction of the proposed impermeable core zone. 23 Project No. 59185V-DSOl Woodward-Clyde Consultants Trash and other material have been dumped on the site. These materials are unsuitable for use in construction of the dam, and will have to be removed before excavating for borrow materials. 1.7.2 Embankment Shell Material Materials for the embankment shell (Zone 1) can be obtained from the area north and west of the proposed dam on the ridge west of the right abutment. Three large dozer-excavated trenches in the pro- posed shell borrow zone indicate that up to 10 ft of com- pletely to moderately-weathered material can be excavated without blasting by using conventional heavy-duty dozers (equivalent to an International Harvester TD-25) equipped with rippers. Harder, less-weathered zones of metavolcanic rock are expected to be encountered during excavation. These zones may break out in rock ranging from 6 to 24-in. diameter. Rocks in this size range are useable as upstream slope protection (Zone 41. Durability tests were made on a sample of material that is expected to be used in Zone 4. The tests consisted of bulk specific gravity, Los Angeles abrasion, and sodium sulfate soundness. The test results indicate that the rock is sound and well suited for its intended use. 24 Project No. 59185V-DSOl Woodward.Clyde Consultants 1.7.3. Drain and Filter Material Concrete sand from local commercial sources was evaluated for use as drainage relief well material (See Section 1.9.3 and Fig. 1.4). An additional potential sand source was investi- gated south of the intersection of Anillo Way and Palenque Street in the community of La Costa. This site is an area of known relatively clean sand. One sample was obtained from this area for grain size analysis (See Section 1.9.3 and Fig. 1.5). The grain size curve indicates that the sample is very poorly graded, and not suitable for use as a filter material. Filter material for the chimney drain and other drains will have to be obtained from commercial aggregate sources in San Diego County (See Section 1.9.3 and Fig. 1.6). 1.8 FOUNDATION CONDITIONS 1.8.1 Degree of Weathering Analyses of data obtained from the pits indicates that approximately 2 ft of topsoil overlies completely- weathered rock. The rock is completely weathered to a depth of about 4 ft below the ground surface, and has decomposed in place to a dark-brown clay and gravelly clay, but generally retains the appearance and structure of rock. Below Eleva- 25 Project No. 59185V-DSOl WoodwardZlyde Consultants tion 535 ft at the dam, alluvial and slopewash soils in- crease the overburden soils to depths as great as 8 ft in some areas. The rock underlying the dam is weathered near the surface; the degree and depth of weathering vary. In general, the rock is moderately to completely-weathered to a depth of about 6 ft below the present surface on the abut- ments, and to about 8 to 10 ft in the valley bottom. Below that, the rock is slightly to moderately-weathered to vary- ing depths, but generally on the order of 25 to 35 ft below the ground surface. Below that level, fresh rock is present. 1.8.2 Dam Foundation Preparation The foundation rock below the soil mantle and completely-weathered rock is strong and provides a good foundation for the dam. To prepare a suitable foundation, the material above Elevation 535 ft within the dam founda- tion area will need to be excavated to a depth of about 4 ft, and the materials below Elevation 535 ft should be excavated to a depth of about 6 ft. Some local spots will require deeper or shallower excavations. Excavated materials can be used, as appropriate, in the core and in the shells of the dam. 26 Project No. 59185V-DSOl Woodward-Clyde Consultants The overburden soils and foundation rocks down to the slightly-weathered rock can easily be excavated by mechanical equipment; no significant difficulty is expected in preparing the foundation for the dam. 1.8.3 Foundation Seepage The possibility of seepage through the foundation rock has been considered; it is our opinion that relief wells under the chimney drain will intercept much of the seepage. A seepage water return system has been incor- porated into the design of the dam to return seepage waters to the reservoir. In addition, topsoils and residual clays within the reservoir area are to remain in place to serve as a relatively impermeable blanket to impede seepage into the underlying rock. 1.8.4 Spillway Foundation Conditions Underlying the spillway area is a variable thick- ness of soil overlying completely to slightly-weathered metavolcanic rock. The rock was examined by excavating backhoe pits to depths on the order of 8 ft within the general spillway area. To evaluate the rippability charac- teristics of the rock, two engineering seismograph traverses made for the previously reported feasibility study were evaluated. The seismograph traverses indicate that rock 27 Project No. 59185V-DS01 Woodward-Clyde Consultants having seismic velocities of 7,000 ft/sec occurs at a depth of between 9 and 15 ft below the existing ground surface. Experience in the San Diego area with rock from the Santiago Peak volcanics indicates that the rippability of the hard rock unit is generally dependent on the degree of decom- position and the frequency and orientation of fracturing. Our past observations of excavation operations in the San Diego area indicate that the results of seismograph traverses can generally be correlated with the difficulty of excava- tion, as previously explained. When apparent seismic velocities are less than 5,000 ft/sec, the materials are generally rippable. Apparent seismic velocities between 5,000 and 7,000 ft/sec have been found to indicate marginal rippability, with the success of the excavation operation depending on equipment performance and operator techniques. When velocities exceed 7,000 ft/sec, it has been our experience that materials normally need to be blasted prior to excavation. 1.8.5 Foundation Condition of ,Inlet-Outlet Works The invert elevation of the inlet-outlet conduit is placed 5 to 8 ft below the existing ground surface so as to be below the prepared ground surface. 28 Project No. 59185V-DSOl Woodward.Clyde Consultants Trenches and borings in the vicinity of the con- duit indicate that moderately to highly-weathered meta- volcanic rock will be present at invert elevation. Con- trolled blasting may be necessary in some areas to facilitate excavation of the trench in which the conduit will be placed. 1.9 LABORATORY TESTS AND MATERIAL PROPERTIES Laboratory tests were performed to evaluate the classification of near-surface soil deposits, suitability of the potential borrow materials for embankment construction, and pertinent geotechnical properties of the embankment ,ials for use in seepage and stability analyses. mater 1.9.1 Embankment Shell Materials A representative sample of the coarse-grained soil from the borrow area for the shell zone was tested for grain size distribution (Fig. 1.7), bulk specific gravity, sound- ness, absorption, and durability. The bulk specific gravity was 2.76. The absorp- tion test (ASTM Test Method cl271 indicated an absorption value of 1.0 percent: this is the saturated surface dry water absorption of the aggregate. The Los Angeles abrasion test (ASTM Test Method C535, Type No.1) indicated a loss of 8 percent at 1,000 revolutions. 29 Project No. 59185V-DSOl Woodward-Clyde Consultants The results of the sodium sulfate soundness test (ASTM Test Method C88) are summarized below: Grain Size % by Weight % LOSS Weighted % Loss 2 to l-1/2 in. 6 0.26 0.012 l-1/2 to 3/4 in. 13 0.72 0.096 3/4 to 3/E in. 9 0.91 0.082 3/E in. to No. 4 4 2.04 0.143 TOTAL: 0.33 These test results indicate that rock chunks of the moderately-weathered rock zones located in the borrow areas downstream of the right abutment and on the ridge east of the spillway are suitable for use in the random zone (Zone 1) of the dam, as well as for upstream slope pro- tection. The sample tested was well graded and is composed of hard, durable rock and some fines. The amount of fines is relatively small and, because of the coarse gradation, the compacted shell material is expected to be very pervious. The shell material will be placed in loose lift thicknesses not exceeding 12 in. and compacted with heavy rubber-tired rollers. Compaction of the random zone will be controlled by specifying the number of passes rather than by controlling the relative density. A fill test in the field is planned to confirm the adequacy of the specified number of passes. 30 Project No. 59185V-DSOl Woodward-Clyde Consultants 1.9.2 Impervious Core Materials 1.9.2.1 Classification Tests Soil classification tests included grain size distribution (Figs. 1.8 to 1.13) and plasticity tests. The results of water content measurements and plasticity tests are shown at the corresponding sample locations on the logs (Figs. 1.14 to 1.52). 1.9.2.2 Compaction Tests Compaction characteristics tests were performed on representative samples of the borrow materials for the impervious core section of the dam (Fig. 1.53). The com- paction test was a modified version of ASTM Test Method D- 1557 in which the standard 4-in. diameter, l/30-cu-ft mold was used, but the material was placed in three layers and compacted under 15 tamps of a lo-lb hammer falling 18 in. This resulted in a compaction energy of 20,250 ft-lb/cu-ft, which is normally used in the compaction of earth dams in California. 1.9.2.3 Strength Tests The effective stress-strength parameters of a sample of the compacted core material were measured by 31 Project No. 59185V-DSOl Woodward-Clyde Consultants performing a slow consolidated-drained (CD) direct shear test (Fig. 1.54). The test was performed on samples com- pacted at the optimum water content to a dry density equal to 95 percent of the maximum dry density obtained in the above described compaction test. The measured effective stress parameters were c' = 400 lb/sq-ft and fl' = 32 degrees. 1.9.2.4 Permeability Tests Laboratory permeability tests were performed on two compacted samples of the representative core materials. Each sample was prepared at optimum water content and at 95 percent of the maximum dry density obtained in the compac- tion test. The permeability tests were constant-head type with back pressure. The compacted samples were assembled in a triaxial testing apparatus and saturated by back pressur- ing. Four different permeability test runs were made on each sample at confining pressures ranging from 1.5 to 4.5 tons/sq-ft. The results of the permeability tests are summarised on the following page. 32 Project No. 59185V-DSOl Woodward-Clyde Consultants Water Dry Confining Coefficient Content Density Pressure of Permeability Sample (%I (lb/sq-in.) (ton/sq-in.) (ft/min) 16-2 17 98 1.5 4.ox1o-7 2.5 3.9x10 -7 3.5 3.8~10-~ 4.5 3.8~10~~ 18-1 26 92 1.5 1.ox1o-7 2.5 1.ox1o-7 3.5 1.8~10-~ 1.9.2.5 Solubility Tests Laboratory tests were performed to assess the soluble salt content of the fine-grained borrow materials. Tests were made in accordance with the Saturated Soil Extract test of the Department of Agriculture. In this test, a sufficient amount of water is added to a 200-gm sample of soil to saturate it; the water is then evacuated from the sample and dissolved solids (parts per million) are estimated by conductivity measurements. The results of the solubility tests, which were performed by Clarkson Laboratory, are summarized below: Soluble Salt Sample (% by weight of soil) 18-2 0.2 16-2 0.1 33 Project No. 59185V-DSOl Woodward-Clyde Consultants Based on the test results, the fine-qrained soils obtained from the soil overburden at the dam site, from the valley bottom immediately downstream, and from the offsite borrow area (Sheets 2 and 3 of the plans) are suitable for use in the impervious core and the upstream blanket zones of the dam. 1.9.2.6 Suitability of Fine-Grained Soils The soils are fine-qrained and have low to mod- erate plasticity, although some highly-plastic clays are also present. When compacted, these fine-grained soils have very low permeabilities (on'the order of 1x10 -7 ft/min to 4x10 L7 ft/min). According to the results of the laboratory tests on two representative samples, the percent of soluble salts in the core material is very small. The specifications provide that the material be spread in loose lifts not exceeding 9 in., watered as necessary to the optimum water content 2 2 percent obtained in a modified version of ASTM Test Method D-1557 (the energy adjusted to 20,250 ft-lb), and compacted with sheepsfoot- type rollers. The specifications also require a minimum relative compaction of 95 percent, as assessed in the com- paction test. 34 Project No. 59185V-DSOl Woodward-Clyde Consultants 1.9.3 Filter Materials Suitable, free-draining, granular materials for the chimney drain (Zone 3) and for backfilling the seepage relief wells were not available on the site or at the offsite borrow area. A gradation test (Fig. 1.5) performed on a sample of potential filter material taken south of the intersection of Anillo Way and Palenque Street in La Costa showed the sample was unsuitable; therefore, samples of nine commercially available filter materials were tested. The results of tests on sand for seepage relief well backfill are shown in Fig. 1.4; the results of tests on Class II filter for use in Zone 3 are shown on Fig. 1.6. The tests show the material designated as Class II filter material is generally satisfactory for use as Zone 3 material in the chimney drain zone. The gradation of this material compared to that of the core material is such that no additional filter zone will be required between the core and the chimney drain. Sand having less than 3 percent fine material is suitable for the seepage relief wells. The chimney drain is 8 ft wide, as shown on the plans. Specifications require that vibratory compaction be used for material placement in this zone. 35 Project No. 59185V-DSOl Woodward-Clyde Consultants 1.9.4 Riprap Rocks larger than 8 in. will be raked to the upstream face where, together with rock excavated from slightly to moderately-weathered areas in the right abutment borrow, they will be placed to provide protection for the upstream slope. The downstream slope will not have rock riprap, but it will be seeded with native grasses to reduce surface erosion. 1.9.5 Analysis The information gathered from site geologic and qeotechnical investigations, as well as laboratory tests, was analysed and utilized in designing the dam, spillway, and inlet-outlet works. The design details and methods of analyses are presented in Part 2. 36 TABLE 1 REPORT OF WATER PRESSURE TEST HOLE NO. e SHEETLOFL PROJECT -STREAM HOLE LOCATION ELEVATION La Costa Dam S-la DATUM START HRS END HRS TOTAL HRS INTERVAL WASHED FT HRS FLOW TEST FLOW PER HOLDING TEST SECTION USED GAUGE PRESSURE AT TEST REMARKS GEGLSGIST D. Elder DATE 6/11/79 HOLE NO. S-la TABLE 1 REPORT OF WATER PRESSURE TEST HOLE NO. s-2 SHEETLOFL _ PROJECT -STREAM HOLE LOCAT I ON ELEVATION La Costa Dam off Channel s-2 DATUM START HRS END HRS TOTAL HRS INTERVAL WASHED FT HRS FLOW TEST HOLDING TEST SECTION USED GAUGE PRESSURE AT TEST INTERVAL REMARKS I GEOLCG I ST D. Elder DATE 6/S/79 HOLE NO. s-2 Woodward-Clyde Consultants TABLE II SUMMARY OF CREDIBLE AND PROBABLE EVENTS Distance from site (miles): Estimated Richter Magnitude (credible event): Estimated Peak Bedrock Acceleration (g's) (credible event): Estimated Richter Magnitude (IOD-year event): Estimated Peak Bedrock Acceleration (g's) (loo-year event): San Jacinto Elsinore San Clemente Rose Canyon Fault Zone Fault Zone Fault Zone Fault Zone 46 23 54 7 7-3/4 7-l/2 7-l/2 6-3/4 0.12 0.20 0.09 0.40 7-l/4 7 -- 6-l/2 0.10 0.20 -- 0.30 / PRESSURE GAUGE CASING- PACKER- I HEAD 1 'FLOW METER %\\V HIGHEST POINT ABOV PRESSURE GAUGE INTAKE MID POINT !:I? TEST SECTION BORE HOLE DEPTH 4HQ3y- DIAMETER NO SCALE 4 TYPICAL FIELD PERMEABILITY INSTALLATION LA COSTA STORAGE RESERVOIR DRAWNBY: mrk CHECKEDBY:-1 PRCUECTNO:59185V-DS01 1 DATE: g-31-79 1 FlOURENO:1.1 WOilOWANO-CLYDE CONSULTANTS 33 M.?IGNIT”rJL . 3.5 3.9 . 1.0-3.4 . 2.5-2.9 . m-2.4 ‘37 Cl c....!, 4 ‘:’ ‘3; ““_“‘:: (After Simons, 1977) EARTHQUAKE EPICENTERS IN SAN DIEGO AREA 1934-1974 T.A COSTA STORAGE RESERVOIR ~~~~ P-21 -79 I FGURE MO: 1.3 -.. _ DR&WBY: mrk CHECKEDBY: u/ PROJECTNO:591$j5V-DSOl 1 DATE: &L,L , I WdDDWARD-CLYDE CONSULTANTS COBBLES GRAVEL SAND SILT and CLAY C0aW.e Fine Coarse Medium Fine 1 Mesh Opening - Ins Sieve Sizes Hydrometer Analysis I I I I 76 32 loo IO 0 90 '1 1, I I , I I I I I I h \,‘\I I I I I I I I I III I, ,I II I IO 60 20 70 30 E?w WEi 2 ZT 2 '= 550 2 "; z s Lw i5 6ob 33 70 m 60 IO 90 0 loo loo 50 10.0 5.0 I.0 .O.l 0.05 0.01 0.005 0.001 GRAIN SIZE IN MILLIMETERS SAMPLE CLASSIFICATION AND SYMBOL 'LL *PI 1 Stevens Sand __~ 2 Coast Sand 3 Marron Brothers 4 Conrock - Mission Valley - 5 Conrock - Lakeside I 'LL - Liquid Limit _-. .~ ~. .~ 'PI - Plasticity Index GRAIN SIZE DISTRIBUTION CURVES FILTER MATERIALS COMMERCIALLY AVAILABLE IN SAN DIEGO LA COSTA STORAGE RESERVOIR DRAWNBY: mrk CHECKEDBY: - PROJECTNO: 59185V-DSOl DATE:. 8-31-79 FlG"RE No: 1.4 WDODWhlD-CLYOE CONSULTANTS COBBLES GRAYEL I SAND SILT and CLAY C0aWS Fine Coarse Med i urn Fine Mesh Opening - Ins Sieve Sizes Hydrometer Analysis I I I I ,nn76 32 lb t 64 IO 16'B3040 60 60 14020 0 .-" 0 90 IO 60 20 GRAIN SIZE IN MILLIMETERS 70 30 60 40 50 50 110 60 30 70 20 60 IO so 0 100 loo 50 10.0 5.0 1.0 0.1 0.05 0.01 0.005 0.001 SAMPLE CLASSIFICATION AND SYMBOL *LL 'PI "A" Fine sand (SP) ‘LL - Liquid Limit *PI - Plasticity Index GRAIN SIZE DISTRIBUTION CURVES REPRESENTATIVE SAI4PLE OF SAND - OFFSITE BORROW AREA LA COSTA STORAGE RESERVOIR DRAWN BY:~ mrk CHECKED BY: p PROJECTNO: 59185V-DSOl 1 DATE: 8-31-79 FI(I"RE No: 1.5 WOOOWARO-CLYDE CONSULTANTS I( C I GRAVEL SAND 1 Coarse SILT and CLAY Fine Coarse Hed i urn Fine 1 Mesh Opening - Ins Sieve Sizes Hydrometer Analysis I I I I 76 32 I9 t ts IO 16iOSOW 0 IO P 30 WEI E 2 "; : 602 70 60 w IM) 50 IO.0 5.0 I.0 ~0. I 0.05 0.01 0.005 0.00- GRAIN SIZE IN MILLIMETERS SAMPLE CLASSIFICATION AND SYMBOL *LL ‘PI 6 Class II AS Conrock 7 Class II AB Fenton (Commercial) 8 Class II AB Fenton (State Spec.) 9 Class II AB Nelson-Sloan (Otay) *LL - Liquid Limit ‘PI - Plasticity Index GRAIN SIZE DISTRIBUTION CURVES FILTER MATERIALS COMMERCIALLY AVAILABLE IN SAN DIEGO LA COSTA STORAGE RESERVOIR DRAWN BY: mrk CHECKED BY: j,.5 PROJECTNO: 59185V-DSOl 1 DATE: *-31-79 FIGURENO: 1.6 WOOOWARO-CLYDE CONSULTANTS I GRAVEL CoBBLES SAND I: arse I Fine I SILT and CLAY " Madi,,m Finn I Mesh Opening - Ins Sieve Sizes Hydrometer Analysis 1 90 IO 80 II 20 76 32 IO 100 162030'+0 6060 140200 0 70 30 2 60 wz z 5 ", z 5" i? "i "w % &'40 600 5 30 70 20 80 IO 90 0 100 IO0 92 10.0 5.0 1.0 0.1 0.05 0.01 0.005 0.001 GRAIN SIZE IN MILLIMETERS . SAMPLE CLASSIFICATION AND SYMBOL 'LL *PI T-1C Gravelly sand (SP) ‘LL - Liquid Limit *PI - Plasticity Index GRAIN SIZE DISTRIBUTION CURVES TYPICAL SHELL MATERIAL LA COSTA STORAGE RESERVOIR DRAWN a-f: mrk CHECKED BY: b 1 PROJECTNO: 59185V-DSOl 1 DATE: 8-31-79 1 FGURENO: 1.7 WOOOWARO-CLYOE CONSULTANTS COBBLES GRAVEL SAND SILT and CLAY Coarse Fine Coarse Medium Fine I Mesh Opening - Ins Sieve Sizes Hydrometer Analysis I I 1 1 0 IO 20 30 WE E "= 50: 3 z 6oe 70 80 90 100 IO.0 5,o I.0 0. I 0.05 0.01 0,005 0,001 GRAIN SIZE IN HILLIMETERS CLASSIFICATION AND SYMBOL *LL *PI 1 *LL - Liquid Limit *PI - Plasticity index GRAIN SIZE DISTRIBUTION CURVES LA COSTA STORAGE RESERVOIR ORAWNW: mrk CHECKED BY: yv PROJECTNO:~~~~~V-DSO~ DATE: 8-31-79 FlOUREND: 1.8 WOODWARD-CLYDE CONSULTANTS IOC !3c 20 IC 0 COBBLES GRAVEL SAND Coarse SILT and CLAY Fine Coarse Medium Fine I I Mesh Opening - Ins Sieve Sizes Hydrometer Analysis I I I 1 76 32 18 t :Ir IO 162oSOKl 6060 IUOXW) I I II!! I! !! !! 1 1 , 0 IO Go 100 IM) 50 ID.0 5.0 1.0 0.1 0.05 0.01 0.005 O.ODl GRAIN SIZE IN MILLIMETERS t SAMPLE 13-2 CLASSIFICATION AND SYMBOL *LL *PI Clayey sand (SC) 54 31 13-3 Silty to clayey sand (SM) 37 12 'LL - Liquid Limit *PI - Plasticity Index GRAIN SIZE DISTRIBUTION CURVES LA COSTA STORAGE RESERVOIR DRAWNBY: mrk CHECKED BY: w PROJECTNo: 59185V-DSOl DATE: 8-31-79 [ FIGUREW: 1.9 WilODWARO-CLYDE CONSULTANTS WCCGS-76 COBBLES GRAVEL I SAND C0arse Fine Coarse Medium I SILT and CLAY Fine I Me~sh Opening - Ins Sieve Sizes Hydrometer Analysis I I 1 I IW VI 10.0 5.0 1.0 0. I 0.05 0.01 0.005 0.001 GRAIN SIZE IN MILLIHETERS SAMPLE CLASSIFICATION AND SYMBOL *LL 'PI 14-1 Clayey sand (SC) 39 18 14-3 Clayey sand (SC) 41 24 15-1 --Silty_- clay (a% 51 32 ~~~~~~~~ *LL - Liquid Limit *PI - Plasticity Index GRAIN SIZE DISTRIBUTION CURVES LA COSTA STORAGE RESERVOIR DRAWN BY:~ mrk CHECKEDBY: cc- PROJECTNO:59185V-DS01 1 DATE: S-31-79 FIGURE No: 1.10 WOOOWARO-CLYDE CONSULTANTS COBBLES GRAVEL I SAND Coarse I SILT and CLAY Fine Finn I Mesh Opening - Ins Sieve Sizes I Hydrometer Analysis 1 1 90 IO 80 m 70 30 60 w:: I 2 50 50= k 2 40 6ok E 30 70 m 80 IO 90 orrl 111 rll I III III I I II 1 I I I IlOO 100 50 10.0 5.0 1.0 0.1 0.05 0.01 0.005 O.OOI GRAIN SIZE IN HILLIMETERS SAMPLE CLASSIFICATION AND SYMBOL ‘LL *PI 16-l. Clayey sand (SC) 32 8 16-2 Clayey sand (SC) 32 7 “LL - Liquid Limit *PI - Plasticity Index GRAIN SIZE DISTRIBUTION CURVES LA COSTA STORAGE RESERVOIR DRAWNBY: mrk CHECKED BY: ti PROJECTNO: 59185V-D~0i DATE: 8-31-79 FlO"RENo:1.11 WtiOOWARO-CLYDE CONSULTANTS WCGGS76 COBBLES GRAVEL I SAND COZlWS Coarse Medium SILT and CLAY Fine Fine I Mesh Opening - Ins Sieve Sizes r Hydrometer Analysis I I I 76 32 100 IO 16203040 60 BO 140200 0 90 IO 80 m 70 30 e 60 WE z E z! E +50 z E-o= z k 2 s 40 60: 30 70 m 80 IO - 0 ~fF!wi~~ilA~ 90 100 100 50 10.0 5.0 I.0 0.1 0.05 0.01 0.005 0.00 I GRAIN SIZE IN MILLIMETERS SAMPLE CLASSIFICATION AND SYMBOL *LL *PI 17-l Silty clay (CL) -- -- 18-l Silty clay (CL) 42 23 ~.. "LL - Liquid Limit 'PI - Plasticity Index I GRAIN SIZE DISTRIBUTION CURVES LA COSTA STORAGE RESERVOIR DRAWN BY: mrk CHECKEDBY: u/ PROJECTNO: 59185V-DS01 DATE: 8-31-79 FIwRENo:1.12 WOOOWARO-CLYOE CONSULTANTS WCCGS-76 COBBLES GRAVEL I SAND C0arse Coarse Medium I SILT and CLAY Fine Fine Mesh Opening - Ins Sieve Sizes I Hydrometer Analysis I I I 100 76 32 IO 162030x) 6080 1'40200 0 so IO 60 20 70 30 60 110 50 50 w 60 30 70 20 60 IO 90 0 100 loo 50 10.0 5.0 IO0 0. I 0.05 0.01 0.005 0.001 T GRAIN SIZE IN MILLIHETERS CLASSIFICATION AND SYMBOL 'LL 'PI 1 *LL - Liquid Limit ‘PI - Plasticity Index I GRAIN SIZE DISTRIBUTION CURVES LA COSTA STORAGE RESERVOIR l DRAWN BY: nrk CHECKED BY: w PROJECTNO: 59185V-DSOl 1 DATE: 8-31-79 PIOURE ND: 1.13 WCGGZ-76 WiJOOWARO-CLYDE CONSULTANTS Location DEPTH 1 IN 9 FEET *MC 12 3 rtsr D*T* ITHEI ‘Em t I I I Boring Number Elevation SAMPLE UUABER I SOIL DESCRIPTION 1 2 L Very dense, damp, brown silty sand (SM) % --I WATER LEVEL At time 0‘ drilling or as indicated. SOIL CLASSIFICATION - soil Clarrificntianr are based on the ““ifid soil Clarrification swem and include cobr, nwirture and canrirtency. Field description. have been modified to reflect rewlfl Of laboratory analyser where approprmte. DISTURBED SAMPLE LOCATION Ob,ained by collecting Ihe auger CYtfings in a plastic or Chh bag. DRIVE SAMPLE LOCATION MODlFlED CALlFORNlA SAMPLER sample With recorded blmw per foot war obtained With a Modified californis drive sampler w inrick diamter. 2.5” outride diameterl line.3 With sarn~k tuber. The UrnpIer was drive” into the Id at the bmf.ml Of die hole with a 140 pound hammer falling 30 inches. INDICATES SAMPLE TESTED FOR OTHER PROPERTIES GS- Grain size Distribution CT - Conrolidation Test LC - Laborator” Ccmwaction ucs - llncon,ined comprerrion Test Tert PI - Atterberg Limifr i-es, DS - Direct Shear Test ST - Loaded Swell Test TX- Triaxid comprerrion Tert cc - Confined Comprerrion Test "P"-Permeability Test NOTE: I" thil mhnn the relultr a‘ tlle*e resu may be recorded where applicable. BLOW COUNT Number Of b,Owr needed to advance *ampler one foot or aI indicated. DRY DENSITY Pow-dr per Cubic Foot MOISTURE CONTENT Percent Of cry Weight NOTESON FIELD INVESTIGATION 1. REFUSAL indicates the inability to extend excwaficm. practically. Widl equipmnt being “red in the investigation. KEY TO LOGS LA COSTA STORAGE RESERVOIR DRAwN8Y: mrk CnEcKED BY: " PROJECT NO:5glB5"-DSol DATE:S-31-79 FlG"RENcl:1.14 WOODWARO-CLYDE CONSULTANTS 0 10 20 1 EAST WEST Dense, dry, way-green, Dense, dry, red-brown clayey Clayey sand (SC) filled fracture Medium dense, dry, yellow-brown sand (SC) TOPSOIL clay seam with slickensided surface, organic material present Hard, blue-green, highly weathered, highly fractured SANTIAGO PEAK METAVOLCANIC l/4” to 6" clay seams ROCK within fractures fra&ures striking E-W and ~45~ very cOINnOn 0 4 Graphic Scale (feet) LOG OF TRENCH 1 - SOUTH WALL LA COSTA STORAGE RESERVOIR DAIWN BY: c j f CHECKED By: Lc- PROJECTNO: 59185V-DSOl DATE: 7-20-79 1 FlC”REwcx 1.17 WOODWARD-CLYDE CONSULTANTS 0 10 20 I I WEST EAST dense. Arv red-brown clayey Medium dense, dry, yellow-brown --..-_, -_l --- -__ aand fSl?l T”P.SOTT. -__.- .-_, -- ----- 1 clayey medium coarse sand (SC) RESIDUAL SOIL , -. _--‘A’--- --- TF.-\- -_- - A-- -- s IT =Q \ 2!!$ y’ \\‘- ,&5+~~ /II # ‘;‘\\ \ Dense, dry, green-gray clayey sand (SC) (highly weathered metavolcanic rock) Hard, blue- green, highly weathered, highly fractured i some fractures contain SANTIAGO PEAK METAVOLCANIC l/8” to l/2” clay ROCK fractures predominantly 0 strike N30-45E and N30-40W dip 75-88NW and N75-88SW l---L-d Graphic Scale (feet) LOG OF TRENCH 1 - NORTH WALL LA COSTA STORAGE RESERVOIR I ~~AwN~Y: cjf CHECKED BY: &, [ PRO.,ECTNO: 59185V-DSOl 1 DATE: 7-20-79 1 F,OURE MO: 1.18 WOODWARO-CLYDE CONSIJLTANTS - - BC - - T- Y -1 - ,THEI ‘EST?, - - 3 ! , -t- Test Pit 2 SOIL DESCRIPTION Loose, damp, brown porous gravelly clayey \ silt (ML) TOPSOIL Gray-brown, moderately weathered, fine grained, hiqhly fractured, tight, closely spaced and clay filled, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Bottom of Hole Test Pit 3 SOIL DESCRIPTION Very stiff, damp, red-brown, porous gravelly clayey silt to silty clay (ML-CL) I TOPSOIL Hard, damp, red brown silty clay (CL) RESIDUAL CLAY Brown to qray, moderately weathered, fine grained, highly fractured, tiqht, closely spaced and clay filled, hard, brecciated meta-tuff SANTIAGO PEAK FORMATION Jointinq - NC,'E 73~'SE, NRS'E 64OSE, N17OE 85'NW Rottom of tio1e 'Far LlesCrlptlO" of r"mbolr,see Figure 1. 14 LOG OF TEST PITS 2 AND 3 LA COSTA STOIWGE RESERVOIR DRAWN BY: ~mrk CHECKED BY: 0 PROJECTNO: 59185V-DS01 DATE: 8-27-79 1 FlOUREIK):1.19 WOOOWARD-CLYDE CONSULTANTS Test Pit 4 ‘DD - - i-1 1 1-2 [ SOIL DESCRIPTION I Hard, damp, red-brown silty clay (CL) \ TOPSOIL Brown-gray, moderately to highly weathered, fine grained, moderately fractured, tight, closely spaced, hard, brecciated meta-tuff I SANTIAGO PEAK FORMATION Highly fractured - 1" diameter Moderately fractured - 12" diameter Refusal Test Pit 5 OEPTH TEST DATA 2, *MC ‘DT”ER SAMPLE *DD WC TESTS NUMBER SOIL DESCRIPTION 1 I / I L\\-d . . r ~ . 1 ,.. . very *r11*, oamp, DrOWn porous s11ny clay (CL) TOPSOIL c El Brown, highly weathered, fine grained, moderately fractured, tight, closely spaced I n hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Refusal I ‘For dercriptlo” of wnbolr. ree Figure 1 14 LOG O? TEST PITS 4 AND 5 LA COSTA STORAGE RESERVOIR DRAWN Bv: mrk CHECV.ED BY: ky PROJECT NO: 59185”-DS”1 DATE: e-27-79 F,G”RE 110: 1.20 WOODWARD-CLYDE CONSULTANTS Test Pit 6 - ,THEI rwrs - ;s , .L=2. 'I=7 - SAMPLE l”MBER SOIL DESCRIPTION Very stiff, damp, red brown silty clay \ (CL) TOPSOIL Hard, damp, red brown silty clay (CL-ML) \ RESIDUAL CLAY Brown-gray, moderately weathered, fine grained, moderately fractured, tight, closely spaced, hard, siliceous meta-tuff \ SANTIAGO PEAK FORMATION Bottom of Hole Test Pit 7 SOIL DESCRIPTION I Very stiff, damp, brown porous gravelly \ silty clay (CL) TOPSOIL Hard, damp, red-brown silty clay (CL) \ RESIDUAL CLAY Brown-gray, moderately to highly weathered, fine grained, highly fractured, tight, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Bottom of Hole ‘For delcrimon Of r”mbolr, see Figure 1.14 LOG OF TEST PITS 6 AND 7 LA COSTA STORAGE RESERVOIR DRAWN BY: mrk CHECKEDBY: w PROJECTNO: 59185V-DSOl DATE: B-27-79 ] FlGURENO:1.21 WOODWARD-CLYDE CONSULTANTS Test Pit 8 - TDA - DD - - 3 SC ; SAMPLE WMGER 3-l 9-2 9-3 Very stiff, damp, red-brown gravelly silty clay (CH) TOPSOIL Hard, damp, yellow-brown silty clay (CL) RESIDUAL CLAY SOIL DESCRIPTION 1 Brown-gray, moderately weathered, fine grained, moderately fractured, tight, closely spaced, hard siliceous meta-tuff SANTIAGO PEAK FORMATION Bottom of Hole - Near Refusal Test Pit 9 SOIL DESCRIPTION 1. Very stiff, damp, brown porous silty clay (CL) with gravels TOPSOIL I Hard, damp, brown to yellow-brown, sandy clay (CL-CR) RESIDUAL CLAY L Brown-gray, moderately weathered, fine grained, moderately fractured, tight, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Bottom of Hole ‘For delCrlPtlOn 0‘ r”mbolr. see Figure 1. 14 LOG OF TCST PITS 8 AND 9 LA COSTA STORAGE RESERVOIR DRAWN BY: mrk CHECKED BY: w PROJECTNO: 591!35V-DSOl 1 DATE: 8-27-79 FIGURE No: 1.22 WOOOWARD-CLYDE CONSULTANTS 0 40 I' ---.-:"-..-- 60 80 ----~--+~- __.. ~~~~._ _ ~~~ -- WEST EAST Highly fractured, sheared ione numerous small offsets Hard, dry, red-brown fine sandy clay (CL) T Hard, dry red-brown, fine sandy clay (CL) with angular rock fragments RESIDUAL CLAY metavolcanic rock Fracture shear zone Very fractured. highly weathered, brown Fracture N5W 85E Fracture NlOE to blue-green, fine grained SANTIAGO Fractured, weathered, blue-green, PEAK METAVOLCANIC ROCK fine grained SANTIAGO PEAK META- VOLCANIC ROCK I I I 0 5 10 Graphic Scale (feet) LOG OF TRENCH 10 LA COSTA STORAGE RESERVOIR DRAWNBY: cjf CHECKED BY: *c PROJECT NO: 59185V-DSOl DATE: 7-20-79 FIGURE ml.23 WOOOWARO-CLYOE CONSULTANTS SOUTH NORTH 0 20 40 60 80 Hard, dry, red-brown fine f Sandy clay CCL] TOPSOIL Hard, dry, red-brown, fine sandy clay (CL) Witn angular rock fragwnts RESIDUAL CLAY Highly weathered, highly frac&ed blue-green breccia SANTIAGO PEAK METAVOLCANIC ROCK .-.- .-'~_-~-~ -- I \ Joint N45E 58NW / t Highly weathered, highly fractured trench collapsed Joint N25E 45NW metavolcanic rock 0 r---L.? Graphic scale (feet) I LOG OF TRENCH 11 LA COSTA STORAGE RESERVOIR I DR~wNw: cjf CHECKED BY: "c. 1 PROJECTNO: 59185V-DSOl 1 DATE: 7-20-79 1 FIOUREWO: 1.24 WOOOWARO-CLYDE CONSULTANTS Test Pit 12 ij!JiiG &; 12-l 1 SOIL DESCRIPTION il Medium dense, moist, brown clayey fine sand (SC) LA JOLLA GROUP Very dense, moist, gray silty clayey fine sand (SM) LA JOLLA GROUP 5 ,_ 10 X, , =;3 12-2 25, LL=3 ?I=1 3/ ] 5l Very dense, damp, orange clayey fine sand , (SC) LA JOLLA GROUP Xi, LL=5 'I=3 Hard, damp, olive gray fine sandy clay (CH) LA JOLLA GROUP - Bottom of Hole Test Pit 13 SOIL DESCRIPTION 1 Hard, damp, gray silty clay (CL) LA JOLLA GROUP DEPTH : I IN FEET *MC ~1 3-2 3-3 4 J Hard, damp, maroon, silty clay (CH) with gypsum interbeds LA JOLLA GROUP 1" thick gypsum Very dense, damp, gray silty clayey fine \ sand (SM) LA JOLLA GROUP 5 1 1 10 1 Bottom of liole *FO,delcri~tion o‘r"mboll,ree Figure 1. 14 LOG OF TEST PITS 12 AND 13 I OFFSITE BORROW SOURCE LA COSTA STORAGE RESERVOIR DRAWN Bv: mrk CHECF.ED BY: w PROJECT NO: 59185V-DS01 DATE: 8-27-79 F,G"RENcx 1.25 WOOOWARO-CLYDE CONSULTANTS Test Pit 14 I DEPTI c IN FEE, TEST DATA DTHER EST.5 SOIL DESCRIPTION Dense, damp, gray fine clayey sand (SC) LA JOLLA GROUP Very dense, damp, orange silty fine sand (SM) LA JOLLA GROUP Dense, damp, gray clayey fine sand (SC) LA JOLLA GROUP Hard, moist, qray to rust-red silty clay (CL) with white opaline concretions L LA JOLLA GROUP Bottom of Hole I ‘MC ‘DD ‘SC 3, LL=3! PI=lF X, LL=41 PI=21 f : 3 I L : I 5 10 Test Pit 15 1 3T”ER ESTS aMPLE IUMBER SOIL DESCRIPTION I Damp, gray brown clayey fine sand ‘DO - ‘GC FILL Hard, damp. maroon laminated silty clay (CH) LA JOLLA GROUP X, LL=51 ?I=32 X, LL=s; ?I=j' 15-l 15-2 Rard, damp, gray silty clay (CH) LA JOLLA GROUP Bottom of Hole *For dercriptlo" ofr"mbolr,ree Figure 1.14 LOG OF TEST PITS 14 AND 15 OFFSITE BORROW SOURCE LA COSTA STORAGE RESERVOIR DRAWN BY: mrk WECKED BY: *J PRoJECTNo: 59185V-DSOl 1 DATE: -8-27-79 1 FIGURE NO: 1.25 WOOOWARO-CLYDE CONSULTANTS TDP - ‘OD - X,LC LL=3i ?I=7 GS Test Pit 16 SOIL DESCRIPTION 1 Hard, damp, red brown sandy clay (CL) \ TOPSOIL Very dense, damp, gray with orange streaks, \ clayey fine sand (SC) LA JOLLA GROUP Very dense, damp, gray clayey fine sand (SC) LA JOLLA GROUP Bottom of Hole Test Pit 17 SOIL DESCRIPTION Hard, damp, gray to maroon silty clay (CL) j with gypsum interzones Gypsum Bottom of Hole ‘For delCription 0‘ rymbolr, see Figure 1.14 I LOG OF T”ST PITS 16 AND 17 OFFSITE BORROW SOURCE LA COSTA STORAGE RESERVOIR DRAWN By: mrk CHECKED sv: * PROIECTNO: 59185V-DS01 DATE: a-27-79 F,GVREMOZ 1.27 WOOOWARO-CLYDE CONSULTANTS Test Pit 18 S,SD - "P -, ,L=4; >1=2- SAMPLE WMBER SOIL DESCRIPTION Hard, damp, maroon silty clay (CL) with thin (less than .l" thick) yellow clay beds LA JOLLA GROUP Bottom of Hole ‘For dercriptlon of r”mbolr, see Figure 1. 14 LOG OF TEST PIT 18 OFFSITE BORROW SOURCE LA COSTA STORAGE RESERVOIR DRAWN By: mrk CHECKED w: (./ PROJECTNO: 59185v-DSol DATE: B-27-79 FlG”RE MO: 1.28 WOOOWiiRO-CLYDE CONSULTANTS Test Pit 19 DEPTH TEST DP PET *MC WD 9 5 _ : WC -- L- ‘BC - l , E 1 c I c I i I -1 DT”EF rESTS LL.=3i PI=8 ~Z DT”ER rEslS X LL=3; 01=1( X LLZ31 ?I=12 LL=6; ?1=4c I I h iAMPLE IUMBER ---l- SOIL DESCRIPTION Loose, damp, brown sand FILL I s N f ! : 1 .I ; ’ ; >- Hard, damp, dark brown clayey silt (ML-CL) \ ALLUVIUM Stiff, damp, dark red brown fine sandy to siltv clav (CL) ALLUVIUM Blue-gray, moderately to highly weathered, fine qrained, moderately fractured, tight, closely spaced, hard, siliceous meta-tuff i SANTIAGO PEAK FORMATION Bottom of Hole Test Pit 20 SOIL DESCRIPTION Loose, damp, brown fine sandy silt (ML) FILL Hard, damp, brown silty clay (CL) ALLUVIUM Stiff, damp, red-brown silty clay (CL) with angular water volcanic gravels ALLUVIUM Stiff to hard, damp, gray silty very fine sandy clay (CH) ALLUVIUM Blue-gray, moderately weathered, fine qrained, moderately fractured, tiqht, closely spaced, hard, siliceous, meta-tuff SANTIAGO PEAK FORMATION Refusal *For descliptlo” of rymbolr. see Figure 1. 14 LOG OF TEST PITS 19 AND 20 LA COSTA STORAGE RESERVOIR I DRAWN 8~: mrk C”ECI(ED BY: Lrv PROJECT NO: 59185V-DSol DATE:g-27-79 FlCi”RE 110: 1.29 WOOOWARO-CLYDE CONSULTANTS - L ‘BC - - l , 1 7 3THEA rEsrS I s N LL=3' PI=11 22-l I 22-2 1 22-3 1 Test Pit 21 1 SOIL DESCRIPTION Medium dense,damp, brown silty-clayey fine to medium sand (SM-SC) TOPSOIL L Very dense,damp, brown highly weathered metavolcanic rock \ SANTIAGO PEAK FORMATION Hard, damp, yellow-brown, medium sandy clay I (CL); completely weathered metavolcanic rock SANTIAGO PEAK FORMATION Bottom of Hole Test Pit 22 SOIL DESCRIPTION Moderately compacted,damp, brown silty fine sand (SM) ACCESS ROAD FILL dense, damp, red-brown silty fine-medium sand (SM) TOPSOIL Dense,damp, red-brown fine to coarse clayey sand (SM) TOPSOIL Very dense, damp, dark gray-brown clayey medium-coarse sar.d (SC) RESIDUAL CLAY Blue-qray, highly weathered, fine grained, moderitely fractured, tight, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Refusal 'FOrderCriDfion o‘r"mbolr,ree Figure 1.14 LCG OF TZST PITS 21 AND 22 LA COSTA STORAGE RESERVOIR DRAWN BY: mrk CHECKEDBY: - PR(YECTND: 59185V-DS01 DATE: B-27-79 FlCURENO: 1.30 WOOOWARO-CLYOE CONSULTANTS iAMPLE IUMBER !3-11 23-2 i SMPLE IUMBER Test Pit 23 SOIL DESCRIPTION Medium dense,damp, brown fine to medium sand (SM) \ TOPSOIL Dense,damp, red-brown clayey sand (SC) \ RESIDUAL CLAY Blue-gray, highly weathered, fine grained, highly fractured, tight, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Bottom of Hole Test Pit 24 . SOIL DESCRIPTION Stiff,damp,brown gravelly silty clay (CL) TOPSOIL \ Stiff,damp,brown silty clay (CL) RESIDUAL CLAY Brown-gray, highly weathered, fine grained. highly fractured, tight, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Bottom of Hole 'Far *ascription 0‘*"mbolr.see Figure 1.14 I LOG OF TEST PITS 23 AND 24 LA COSTA STORAGE RESERVOIR I OraWN Bv: m*k CHECKED BY: LU PRWEflNO:59185V-DSOl DATE: 8-27-79 FIOUREWO: 1.31 WOOOWARO-CLYDE CONSULTANTS 1 DATA 3THEI R s iAMPLE rE.sTS N IUMBER SIMPLE IUMBER Test Pit 25 SOIL DESCRIPTION I Stiff, damp,red-brown gravelly silty clay (CL) RESIDUAL CLAY Hard, damp, brown sandy clay (CH) \ RESIDUAL CLAY Brown-gray, highly weathered, fine grained, highly fractured, tight, closely spaces, hard, siliceous meta-tUff SANTIAGO PEAK FORMATION Bottom of Hole Test Pit 26 SOIL DESCRIPTION Loose, damp, brown silty sand (SM) ACCESS ROAD FILL Gray, highly weathered, fine grained, highly fractured, tight, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Bottom of Hole *For description 0‘ rvmbolr. see Figure 1. 14 LOG OF TEST PITS 25 AND 26 LA COSTA STORAGE RESERVOIR DRAWN By: ~mrk WWXEOEY:,, PROJECTNO: 59185V-DSOl DATE: S-28-79 FlOUREno: 1.32 WOOOWARD-CLYDE CONSULTANTS Test Pit 27 5 DEPTH TEST DATA IN FEET *hJf2 l - iAMPLE IUMBER SOIL DESCRIPTION Loose, damp, brown silty fine sand(SM) ACCESS ROAD FILL Hard,damp, gray-brown silty clay(CH) RESIDUAL CLAY Gray, highly weathered, fine grained, highly fractured, tiqht, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Bottom of Hole Test Pit 28 SOIL DESCRIPTION Medium dense,damp, brown silty fine-medium sand (SM) TOPSOIL Hard, damp, brown silty clay (CL) RESIDUAL CLAY Gray, highly weathered, fine grained, highly fractured, tight, closely spaces. hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Shear zone 2%' - 3' - nearly horizontal %" - 1" clay seam Refusal *For description O‘rymbolr.see Figure 1.14 I I LOG OF TEST PITS 27 AND 28 I LA COSTA STORAGE RESERVOIR CHECKED BY: w WOODWARD-CLYDE CONSULTANTS DEPTH T IN - FEET *MC 5- DEPTH I FL& *MC 7 - TDP - ‘00 - - rr 0, -DD - - ,T - L ‘GC - - - - ‘EC - - - JTHEI WSTS - - 3THEI rESTS - - R Test Pit 29 iAMPLE IUMBER SOIL DESCRIPTION I I SAMPLE YUMEER Medium dense, damp, silty fine sand (.%I) TOPSOIL Hard, dam.p, fine sandy clay (CH) \ ALLUVIUM Hard, damp, silty to fine sandy clay (CH) ALLUVIUM \ Dense,damp, silty medium-coarse sand (SM) ALLUVIUM Gray, highly weathered, fine q-rained, I highly fractured, tiqht, closely spaced, hard, siliceousmeta-tuff SANTIAGO PEAK FORMATION Refusal Test Pit 30 SOIL DESCRIPTION I Hard, damp, red-brown silty to sandy clay (CL) ALLUVIUM Dense, damp, qray, clayey medium sand with rock fragments (SC) SANTIAGO PEAK FORMATION Green-gray, highly weathered, fine qrained, moderately fractured, tight, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORNATION Refusal LOG OF TEST PITS 29 AND 30 LA COSTA STORAGE RESERVOIR DRAWNBY: ~mrk CHECKEDGY: &, PRG.,ECT NO: 59185V-DSOl DATE:+28-79 FlGUREWO:1.34 WOODWARD-CLYDE CONSULTANTS DEP, c IN PEE 5 1 - 1 - ‘MC - - - iT 01 - -00 - - Test Pit 31 Approximate El. 527' SOIL DESCRIPTION Stiff, damp, red-brown silty clay (CL) \ TOPSOIL \ Stiff, damp, red-brown silty clay (CL) RESIDUAL CLAY Gray, highly weathered, fine qrained, \ moderately fractured, tight, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Refusal Test Pit 32 SAMPLE II”M%ER SOIL DESCRIPTION Hard, dame, brown fine sandy clay (CL) \ TOPSOIL Dense, damp, brown silty to fine sand (SM) / TOPSOIL Dense, damD, brown fine clayey fine sand (SP) with rock fragments SANTIAGO PEAK FORMATION Brown-gray, hiqhly weathered, fine qrained, moderately fractured, tiqht, closely swced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Refusal 'Fardercrlptlon 0‘r"mbolr.ree Figure 1.14 LOG OF TEST PITS 31 AND 32 LA COSTA STORAGE RESERVOIR DRAWNBY: mrk C"ECKED BY: ky PRO.JECTNO:~~~~~V-DSO~ DATE: U-28-79 PlOURE Nod. 35 WOODWARO-CLYDE CONSULTANTS Test Pit 33 5- rD/1 - ‘DO - FE - ‘DO - - - ‘BC - - - ‘BC - 3THER EYrS XHER ESTS SOIL DESCRIPTION I Firm, damp, silty clay (CL) TOPSOTL Stiff, damp, yellow-brown silty to fine sandy clay (CL) RESIDUAL CLAY Brown-gray, highly weathered, fine qrained, highly fractured, tight, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Refusal Test Pit 34 SOIL DESCRIPTION Loose, damp, red-brown clayey fine sand (SC) \ TOPSOIL Hard, damp, olive, gravelly fine sandy RESIDUAL CLAY Brown, highly weathered, fine grained, Refusal *For dercrimio" Of r"mbolr,ree Figure 1. 14 LOG OF TEST PITS 33 AND 34 LA COSTA STORAGE RESERVOIR DRAWNEW mrk CHECKED BY: w PRC,JECTNO:~~~~~V-DSO~ DA&3-28-79 F,O"RENoz1.36 WOODWARD-CLY,DE CONSULTANTS ZITHER m3TS Test Pit 35 Approximate El. 560' SOIL DESCRIPTION I Medium dense,damp, brown. silty clayey \ fine sand (SM-SC) TOPSOIL Red-brown, highly weathered metavolCaniC rock SANTIAGO PEAK FORMATION Refusal Test Pit 36 SOIL DESCRIPTION I Hard,damp, brown silty clay (CL) L TOPSOIL \ oense,damp, brown silty clayey fine sand (SM-SC) RESIDUAL CLAY I Red-brown, highly weathered, highly fractured metavolcanic rock SANTIAGO PEAK FORMATION Refusal *For dereriptio” 0‘ rymbalr, ree Figure 1.14 LOG OF TEST PITS 35 AND 36 LA COSTA STORAGE RESERVOIR DRAWNBY: mrk C~ECKEDBY: w PR‘,JECTNO:59185V-DSOl DATE: 8-28-79 PlO"REN0: 1.37 WOODWARD-CLYDE CONSULTANTS Test Pit 37 5- r D, - DD - - - SAMPLE JVMBER SAMPLE WMBER SOIL DESCRIPTION Hard, damp, red-brown silty clay (CL) TOPSOIL Firm, damp, red-brown silty to fine sandy clay (CL) RESIDUAL CLAY Red-brown, very highly weathered, very highly fractured metavolcanic rock I SANTIAGO PEAK FORMATION Refusal Test Pit 38 SOIL DESCRIPTION I \ Hard, damp, brown silty clay (CL) TOPSOIL I drown-gray, highly weathered, fine qrained, highly fractured, tight, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Refusal LOG OF TEST PITS 37 AND 38 LA COSTA STORAGE RESERVOIR DRAWN By: mrk CMCKED BY: *v~ PROJECT NO: 59185V-DSOl DATE:E-28-79 FIGURE M‘W.38 WOODWA~RD-CLYDE CONSULTANTS Test Pit 39 DEPTH TEST DATA FET Tr *I3 -. *MC THER SAMPLE *m WC I 6STS NUMBER SOIL DESCRIPTION Hard, damp, brown silty clay (CL) \ TOPSOIL \ Very dense,damp,red-brown clayey sand (SC) RESIDUAL CLAY 5 Blue-gray, moderately weathered, fine grained, highly fractured, tight, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Joints: N50%, 63'-75'N - moSt prominent N45'E. 70'NW Test Pit 40 SOIL DESCRIPTION Hard, damp, brown silty to fine sandy clay (CL) TOPSOIL Blue-gray, highly weathered, fine grained, highly fractured, tight, closely spaced, hard, siliceousmeta-tuff with clay seams SANTIAGO PEAK FORMATION Joints: N5S0E, 70'NW N4S0E, 60'NW N60°E, 75'NW prominent N65"E. vertical N65OW, 55'NE prominent Refusal LOG OF TEST PITS 39 AND 40 Li, COSTA STORAGE RESERVOIR DRAWN sv: mrk CHECKEO BY: I,/ PROTECT N~I: 59185V-~S01 DATE&28-79 FlGVRENo: 1.39 WOOOWARO-CLYDE CONSULTANTS - TDP - 'LID - DTHER WSTS JTHEI rE?iTS iAMPLE IUMBER AMPLE UMBER Test Pit 41 SOIL DESCRIPTION I Hard, damp, brown. silty to fine sandy clay (CL) \ TOPSOIL Blue-gray, highly weathered, fine grained, highly fractured, tight, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Joints: N45"E, 80"NW: prominent N70°W, 38ONE NSO'W, 38'NE N55OW, 60°SW; prominent N60"E, vertical; Drominent Refusal Test Pit 42 SOIL DESCRIPTION Hard, damp, brown silty to fine sandy clay (CL) TOPSOIL Very dense, damp, red-brown clayey sand (SC) grading to a blue-gray, highly weathered, fine, grained, highly fractured. tight, closely spaced, h,ard, siliceous meta-tuff SANTlAGO PEAK FOR"ATION Joints-clay filled: N-S, 82'NW N40°E, 75'SE N45%, GOoNE Refusal ‘For dercrimion Of rymbolr. see Figure 1.14 LOG OF TEST PITS 41 AND 42 LR COSTA STOFJAGE RESERVOIR DRAWNBY: mrk CHECKED BY: d PRQ~ECT ND: 59185V-D~01 ~~~~:8.-28-7'3 ,=,G”RENO: 1.40 WOOOWARO-CLYDE CONSULTANTS Test Pit 43 5 n I I 4 I ;T DA TEST DI ‘MC - - SC - - - ,T”EP ‘ESTS - SAMPLE l”MBER SAMPLE lULlBEN SOIL DESCRIPTION Hard, damp,brown. silty to fine sandy clay (CL) TOPSOIL Blue-gray, highly weathered, fine grained, hiqhly fractured, tiqht, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Joints - clay filled in 2 - 3" shear zones: E-W, 50'S NSO'E, 8Z0SE N40'W. 78"NE Refusal Test Pit 44 SOIL DESCRIPTION I Hard. damp, brown silty clay (CL) TOPSOIL \ Blue-gray, highly weathered, fine grained, highly fractured, tiqht, closely spaced, hard, siliceous meta-tuff; localized shear ~~ne N45"W, 85'vertical; scm? clay in joints I SANTIAGO PEAK FORMATION Refusal *For darcriptlon 0‘ rymtdr, see F,gur* 1. 14 LOG OF TEST PITS 43 AND 44 LA COSTA STORAGE RESERVOIR DRAWN BY: mrk CHECKEDBY: *L/ PRWECTNO: 591HSV-DSOl DATE: 8-29-79 FIGURE No: 1.41 WOODWARD-CLYDE CONSULTANTS Test Pit 45 I i SOIL DESCRIPTION I Hard, damp, red-brown silty clay (CL) TOPSOIL Blue-gray, silty-sandy, highly weathered, fine grained, highly fractured, tisht, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Joints: N35'E, 68OSE; prominent N2S0E, 45OSE N25'E. 50"SE Refusal Test Pit 46 SOIL DESCRIPTION --_-__. --1 Hard, damp, red-brown, silty to fine sandy clay (CL) TOPSOIL Brown, very highly weathered, highly fractured, fine qrained, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Refusal 'Fordercriptlon ofr"mbalr,ree Figure 1. 14 LOG OF TEST PITS 45 AND 46 LA COSTA STORAGE RESERVOIR ORAWN BY: mrk CHECKED BY: w PROJECTNO: 59185V-DSOl DATE: 8-29-79 FIGURE wo: 1.42 WOOOWAilO-CLYDE CONSULTANTS Test Pit 47 5 ~ DT”ER rESTS T I SOIL DESCRIPTION Hard, dame, silty to fine sandy clay (CL) with pebbles of metavolcanic rock ALLUVIUM Blue-qray, highly weathered, fine qrained. hiqhly fractured, tight, closely s~paced, hard, siliceous meta-tuff; thin layer 5-54'; 4" of qray-green silty clay (CH) SANTIAGO PEAK FORMATION Refusal Test Pit 48 SOIL DESCRIPTION Hard, darn?, brown silty to fine sandy clay (CL) TOPSOIL Changing from brown to blue-qray, hiqhly weathered, fine qrained, hiqhly fractured, tight, closely spaced clay seams, hard, siliceous meta-tufd SANTIAGO PEAK FORMATION Joints: N30°W, 50'NE N45OW. 20°NE N50°E, 72'NW Refusal 'For delcrwtlo" 0‘I"lnbo16.ree Figure 1. 14 LOG OF TEST PITS 47 AND 48 LA COSTA STORAGE RESERVOIR DRAWNEW: mrk CHECKEDBY:& PROJECTNO: 59185V-DSOl OAT&-29-79 FlO"REN0z1.43 WOOOWARO-CLYDE CONSULTANTS .TD/ - ‘00 - - - BC - - OTHEF TESTS I Test Pit 49 SOIL DESCRIPTION Hard, damp, brown silty to fine sandy clay I (CL) TOPSOIL Gray-blue, hiqhly weathered, fine grained, highly fractured, tiqht, closely spaced, hard, siliceous meta-tuff SANTIAGO PEAK FORMATION Refusal -FOrdercription afrymbolr,ree Figure 1.14 LOG OF TEST PIT 49 LA COSTA STORAGE RESERVOIR ORAWNBY: mrk CHECKEDBY: w PRoJECTNO:~~~S~V-DSO~ DATE: 8-29-79 FlG”RE NO: 1.44 WOOOWARO-CLYDE CONSULTANTS LEYlTlOl DEPTH LEGEN, ~ CLASSIFICATION OF MATERIALS w3acrlpt,d t t R- = CORE RUN NUMBER RQD = ROCK QUANTITY DXSIGMATOR -!-A Total lenqth of rock core greater then 4 inches in a run, divided by lenqth of core run times 100 (expressed as a percent) -SOIL CLASSIFICATION soil classifications are based on the Unified sdil Classification System and include colrir, moisture and consistency. Field descriptions have been modiEied to reflect results of laboratory analysis where appropriate. -ROCK CLASSIFICATION Rock classifications are based updn examination of physical properties of rock during drilling, an examination of cores recovered, and petrographic analysis. Also indicates geologic formation name. DEPW, BELOW GROIJND SIJRFACE, TN FEET KEY TO CORE BORING LOGS I 1,~ COSTA STORAGE RESCVOIR DRAWNBY: Cl? I ,wr,%.nav./u/l C~~NCCTIYO: 59185V-DSOl 1 O.TE: 8-31-79 I FI(I"RENozl.45 WOOOWARO-CLYDE CONSULTANTS ine sand (SM) ALLUVIUM medium grained, closely spaced, clay filled, hard, gently dipping brecciated meta-tuff SANTIAGO PEAK FORMATION Trouble with casing moved 5' and redrilled and reset casing 4' @ steel casing to blowout 5-30-79; moved to - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - No. S-1a Irlz.l~LLA,,“Il nnt.4 --lFzJ : - -- NAME OF DRILLER ~ 14.TOTP.LNUMBERCORE BOXES 4 MARV IVERSON 15. ELEVATION GROUNO WATERNone Enco"ntered DlRECTlON OF HOLE (XJVERTICAL ~WCLlNED 16. DATE HOLE jSTARTE0 ,COHPLETED DEC. FROM "EIT. ( 5-31-79 j 6-4-79 18. TOTAL CORE RECOVERY FOR BORlNG 89% 5 19. SIGNATURE OF INSPECTOR ,TOTAL DEPTH OF HOLE 41.15' D. ELDER ALLWIUM Hard, damp, red-brown fine sandy silty clay (CL) ALLWIUM Brown t-0 gray on surface, completely weathered, medium grained, very highly fractured, tight, closely spaced and clay filled; hard, gently dipping \brecciated meta-tuff to way, hishlv __ __ weathered, fine grained, highly fractured, tight, closely spaced and clay filled, hard, gently dippin siliceous meta-tuff SANTIAGO PEAK FORMATION 5% 5 in/fi 1% .4 in/ft - R-l - R-2 R-3 REMARKS Prillinp fine, vate* loa., .hp(h 0, weathr‘n0, em., if *inni,icanr, I 5.3’ - QD=O 6.2’ r 10.75' I QD=O IRILLING LOG (Cd SheetJ/ELEV%? fop OF ““’ Hole No. S-la ,O,Ecl I INST*LLAIION I SHEET 2 35’ T TA STORAGE RESERVOIR DAM DEPTH LEGEND CLASSIFICATION OF MATENALS c D,,‘,p,i"#, , T 7. oxit RECOV- ERY e 31% 3.4 nir/f CJY 0 IAMPLI NO. < R-3 Brown to gray, highly weathered, fine grained, I highly fractured, tight, I closely spaced and clay I filled, hard, gently dipping siliceous meta-tuff SANTIAGO PEAK FORMATION ,: i-5 t-6 L 30% 7.6 nin/f LOO% 3.4 xin/fi .OO% .9 lir/ft 3.2% 4.95 in/ft 17.3' L RQD=O L RQD=O 22.3' - - RQD=O - Light brown to light olive green, moderately 1 weathered with clay and iron : stains on fractured surfaces,n fine grained, moderately to highly fractured, tight and closely spaced, hard, flat j bedded, siliceous meta-tuff SANTIAGO PEAK 1 FORMATION 119 = c I 1 1 c I 123 -A Dark green to dark gray, moderately to slightly weathered, fine grained', 0 highly fractured, tight, closely spaced, hard, flat bedded, siliceous meta-tuff SANTIAGO PEAK FORMATION t 8 i 2 m /25 1-I iE 1-7 ROD=0 a Horizontal bedding - fault E very highly weathered fi ,.,:, ;:. j i DRILLING LOG (Cod Sheet) “y$?‘: To’ OF ““’ Hole No. S-la 1 SHEET 3 I I PI POlE” INST*LUIION LA COSTA STORAGE RESERVOIR DAM L CLASSIFICATION OF MATERMS , D<rrripnion, d weathered, fine grained, highly fractured, tight, closely spaced, hard, flat bedded, siliceous meta-tuf SANTIAGO PEAK ~FORMATION fractured, tight, closely spaced, hard, flat bedded, siliceous meta-tuff SANTIAGO PEAK FORMATION Rock becoming increasing hard- less fractured % R 1 n f i 2 m Y 1 4 ‘II : COR ECOV ERY P 100% Z7.8 h-i/ ‘0% !4.8 ,in/i .OO% ,4 IiIJf E ft t t ox 0 iAMPLl NO. f t-8 7-9 t-10 ,,,s,,I ,Od,itr~ rim. “,atlr hr. dcp‘h 0, wmthrnng. CI‘., 8, np,Jkz”?, l---‘-K 34.8' ROD=0 36.25' RQD=O - - Y-l-Y- c-7 ..“I. ,..a Y ‘. DRlLLlNt LOG Dl”lS,ON INST*LL*TION SHEET 1 DAM OF 3 SHEETS PROJECT !O.SIZE AND TYPE OF BIT NQ3 LA COSTA STORAGE RESERVOIR II. DATVM FOR ELEVATION SHOWN o-BM or Ms‘) LOC*TIOH woodmata~ 0, srarrmJ PLAN CENTER OF DAM 92. M*N"F*CT"RER'S DESIGNATION OF DRILL ORlLLlNG AGENCY WOODWARD CLYDE CONSULTANTS .,.~ MOBILE B-53 P 13. TOTAL NO. OF OVER- HOLE NO. CA. .hom 0" d,.llv,"~ t,tls[ ,DIST"R~)ED i "NDllTURBED -- and we nm*sJ j s-2 BURDEN SAMPLES TAKEN i j -- NAME OF DRlLLER ~ II.TOTAlNUHBERCORE BOXES 3 MARV IVERSON 15. ELEVATION GROUND WATER None Enco"ntered DlRECTlON OF HOLE 16. DITE HOLE ISTARTED ,COMPLETED I-JYERTlCAL ~lNCLlNE0 DEO. FROM "ERT. / 6-5-79 i 6-8-79 ~ $7. ELEVATION TOP OF HOLE 530' THICKNESS OF OVERBURDEN 8.4 1 < IB.TOTALCORERECOVERY FOR B~R,NG~~% 7 DEPTH DRlLLED INTO ROCK -- 19. SIGNATURE OF ,NSPECTOR TOT*LoEPTHOF HOLE 34.5' D. ELDER IEVATION OEPT" LEGEND CLASSIFICATION OF MATERIALS g&y EAqp$ REMARKS ~Dsacrimimd ERY NO. mrNling lime, Wats, km.. depth Of 0 b c d ve.thsrhg, stc., i, .,gnws.m) . , P Loose,damp, red-brow,, clayel fine sand to sandy clay ALLUVlUM brown silty fine sandy Firm, damp, gray, silty fine sandy clay (CL) ALLUVIUM closely spaced, hard, flat bedded, brecciated meta-tuf - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - GRILLING LOG (Cat Sheet) EL~~oN,‘op Of “” kOE” IINsT*LL4IION LA COSTA STORAGE RESERVOIR I ~~-~~~~~ DAM Hole No. s - 2 SHEET * - % COR RECO” ERY e ox 0 iAMPLl NO. f ELEVATIOh a 1 't- 1 :t I t F r t t F t J- I red, d Gray, moder :ely fine grained, moderately to highly fractured, tight, closely spaced, hard, flat bedded, brecciated meta-tuff I t I -- SANTIAGO PEAK FORMATION 75% L 37% !l in/f R-4 11 < n 1 ; n c 1 i I 1 L 1-5 RQD=O LOO% z5.4 in/f 1-6 23.6 t-7 L-8 -00% !6.5 in/f RQD=O 26.5 f Blue-green, moderately weathered, fine grained, moderately fractured, tight, closely spaced, clay filled, hard, flat bedded, brecciated Wta-tuff; fine grained dike intruding brecciated meta-tuff SANTIAGO PEAK FORMATION 19% 14.7 in/f RQD=47% - ELEVATION TOP or HOLE IRILLING LOG (Cod Sheet) 530T KM” INsT*LlATION LA COSTA STORAGE RESERVOIR DAM Hole No. ‘-’ I WET 3 ELE”*TlOh -A-- I ~--- CLASSlFlCATlON OF MATERIALS Irkrripron, Blue-green, moderately weathered, fine grained, moderately fractured, tight closely spaced, clay filled hard, ~Elat bedded, brecciated meta-tuff grained dike intruding breeciated meta-tuff SANTIAGO PEAK FOFLVATION Bottom of Hole - LOO% il in/j R-9 3L..lL- RQD=O - - --_..-- ~._ --_..-- ~._ - L^ - L^ PLASTICITY CHARACTERISTICS Liquid Limit, % Plasticity Index, % Classification by Unified Soil Classification System 80 ZERO AIR VOIDSCURVES ,130 SG 2.70 SG GRAIN SIZE, mm MECHANICAL ANALYSIS DIRECT SHEAR TEST DATA Dry Density, pcf Initial Water Content, % Final Water Content, % Apparent Cohesion, psf Apparent Friction Angle, degrees I SWELL TEST DATA I I I I ASTM-D 1157 Modified as follows: l/30 CF meld, 3 l~ayers, 15 tamI’!; by a 10 pouncl hammer Falli~liq Lii”; Compactlo” i:nerqy =20.250 fcm- jx~unds per cubic foot. Optimum Moisture Content, % 10 20 30 40 LABORATORY COMPACTION TEST Initial Dry Density. pcf Initial Water Content, % Final Dry Density. pcf Final Water Content, % sad, psf Swell, percent COMPACTION TEST METHOD: FILL SUITABILITY TESTS LA COSTA STORAGE RESERVOIR DRAWN BY: mrk t"ECKEoeY: cv PROJECTNO: 59185V-DSOl DATE: B-31-79 F,O"RE NO: 1.53 ..,..11..,.mm . . Y,.C nnu...,. %...I.... 8000 4 ‘u ‘u z u” m‘ 6000 : $3 2 : s ii 2l 2 6 4000 ;2 “““I” 0 0.1 0.2 0.3 0 1 2 3 4 Deformation, In. Normal Effective StreSS, tsf Normal Stress. prf 4116 8186 1 I TEST DATA I Type of Test: ConsolidJtEd-DrJiiled (CD) Direct Shear -- Angle of Friction, Effective L? = 32 Cohesion. Effective C’ = 400 psf 1 Rate of Shear. inlmin 0.000192 SLOW DIRECT SHEAR TEST LA COSTA STORAGE RESERVOIR DRAWN BY: mrk CnECKEDtw: v PROJECTNO: 59185"-DSOl IDATE: A-31-79 FIGURE NO: 1.54 WOOOWARO-CLYDE CONSULTANTS Project No. 59185V-DSOl Woodward-Clyde Consultants PART 2 - DESIGN OF DAM, SPILLWAY, AND OUTLET WORKS 2.1 EMBANKMENT DESIGN 2.1.1 General Features of the Embankment The alignment of the embankment was chosen by considering the topographic features of the site and the available geologic information. The embankment geometry and material zones were selected based on availability of suit- able borrow materials, foundation conditions, seepage consid- erations, and slope stability analyses. The embankment is designed as a zoned dam having a central impervious core. The impervious section is flanked by a pervious, random, granular shell. A chimney drain covers the entire downstream face of the impervious core, and is drained by a 6-in. diameter, perforated pipe at the bottom of the chimney. This pipe is connected to two unper- forated collector pipes that discharge into a concrete-lined sump at the toe of the dam. Any water accumulated in the sump will be pumped back into the reservoir. The dam foundation is characterised by a rela- tively thin (0 to 4 ft) layer of topsoil and highly-weathered rock, underlain by metavolcanic bedrock in various degrees of weathering. The design provides for the removal of the topsoil and completely-weathered rock to depths ranging 37 Project No. 59185V-DSOl WoodwardClyde Consultants from 4 ft (above Elevation'535 ft) to 6 ft (below Elevation 535 ft). The available data indicate that the bedrock below the proposed excavation levels is relatively tight and does not require a cutoff system. Nevertheless, as a precaution against undesirable seepage in the downstream toe area, the design includes a series of relief wells spaced 6 ft apart and drilled into the rock to a.depth of 35 ft below the foundation preparation depth to intercept possible seepage through the rock joints. The wells will discharge into the perforated pipe located at the base of the chimney drain. The design provides for rock riprap slope protec- tion for the upstream slope; the downstream slope will be seeded with grass to reduce surface erosion. 2.1.2 Embankment Geometry A typical embankment section is shown on Sheet 5 of the plans. The crest of the dam is 25 ft wide; the upstream slope has an inclination of 3 to 1 (horizontal to vertical), and the downstream slope has a 2-l/2 to 1 inclin- ation. The design elevation of the dam crest is 598.5 ft, but the crest has a camber of 12 in. and a 2 percent drainage slope toward the pool. Thus, the key elevations for the dam crest are: 38 Project No. 59185V-DSOl Woodward-Clyde Consultants 0 Upstream edge of.the crest at Station 16+80 is Elevation 599.5 ft, tapering down to Elevation 598.5 ft at abutments. 0 Downstream edge of crest is 6 in. higher than upstream edge. The top of the dam is 4 ft above the maximum operating pool level (spillway crest), and 2 ft above the reservoir at its probable maximum flood (PMF) level. Opera- tion studies indicate the reservoir level will normally be lower than the spillway crest (Elevation 594.5 ft); hence, the spillway would seldom spill. The core section is 15 ft wide at the top, and has l/2 to 1 side slopes (horizontal to vertical). The top of the core is at Elevation 596.5 ft. Upstream of the core is an impervious blanket that extends a distance of 50 ft when the blanket occurs at levels below Elevation 577.0 ft, and extends all the way to the upstream toe when it occurs at levels higher than Elevation 577.0 ft. The thickness of this upstream blanket ranges between 10 and 12 ft at the upstream edge. The blanket is designed to reduce the volume of seepage through the dam foundation. The chimney drain is 8 ft wide and has the same l/2 to 1 (horizontal to vertical) slope as the core. The design elevation of the top of the chimney drain is 594.5 ft. The upstream slope protection riprap is 8 ft wide, as shown on the plans. 39 Project No. 59185V-DSOl Woodward-Clyde Consultants Based on the data obtained from the borings and pits, it is expected that the depth of foundation excavation in most areas will be between 4 and 6 ft (Sheet 5 of the plans). The actual depth of required foundation excavation might vary and can only be assessed during construction. 2.1.3 Seepage Control Features The seepage control elements of the design consist of an impervious core, an upstream blanket, a chimney drain and collector pipes, and a series of relief wells. The geometries of the core and the chimney drain were discussed in the previous sections. At the bottom of the chimney drain, there is a 6-in. diameter, perforated ACP (Transite Class 200) drainage pipe that collects the seepage water (Sheet 5 of the plans). The perforated drainage pipe at the toe of the chimney drain discharges into two unperforated collector pipes: one with invert at about Elevation 522.25 ft, and another with invert at about Elevation 520.0 ft. The two collector pipes lead into the concrete-lined sump at the downstream toe of the dam. Any water accumulated in the sump will be pumped back into the reservoir. Although the available geologic data indicate that the bedrock is tight, some seepage might occur in the upper 20 to 40 ft of the weathered rock. To intercept this possible 40 Project MO. 59185V-DSOl Woodward-Clyde Consultants seepage, a series of 35-ft'deep, 5-in. diameter wells will be drilled into the bedrock of the dam at 6-ft'centers. The line of wells, which will be located at the base of the chimney drain, will be filled with free-draining filter material and will discharge into the perforated pipe. 2.1.4 Embankment and Excavation Quantities Based on the proposed embankment section, volumes of materials for various zones of the embankment were computed. The approximate volume of foundation excavation under the dam was computed assuming an average excavation depth of 4 ft: Zone Description 1 Random shell including riprap 2 Impervious core 3 Chimney drain and relief wells 4 Foundation excavation Volume (cu-yd) 112,000 35,000 7,000' 39,400 2.1.5 Freeboard Freeboard is the vertical distance between the crest of the embankment and the reservoir water surface. Sufficient freeboard must be provided during inflow from the design flood. Additionally, the freeboard must be capable of preventing overtopping of the embankment by severe wind- 41 Project No. 59185V-DSOl Woodward-Clyde Consultants induced waves and their associated wave run-up. The outer surface of the embankment must also be capable of sustaining the repeated pounding of wind-induced waves along the entire water surface of the embankment, which may be exposed to a surface during normal operations of the facility. The storage reservoir has a maximum operat .ing pool fetch of approximately 1,100 ft. For this condition, we have studied the effects of wind- i, nduced waves generated from loo-mph winds from the east ( such as a Santa Ana,condi- tion). We have also evaluated wind-induced waves generated from a 50-mph eastern wind on a water surface 2 ft above the weir (maximum water surface.Elevation 596.5 ft). These wind conditions generate the following design waves and wave run-ups: Design Wind Water Surface Speed (mph) Elevation (ft) 100 594:5 50 596.5 Wave Conditions 2.2 ft wind wave 1.3 ft run-up 1.0 ft wind wave 0.5 ft run-up For these conditions, we have selected a crest elevation of 598.5 ft, which exceeds both of the design wave freeboard criteria. The 25-ft width of the crest, which slopes toward the reservoir surface at 2 percent, provides an additional l/2 ft of freeboard at the downstream edge of the crest; this provides an additional safety factor. 42 Project No. 59185V-DSOl Woodward.Clyde Consultants From a practical standpoint, it should be noted that the typical weather patterns in southern California result in westerly winds much of the year. The only strong easterly and northeasterly winds result from Santa Ana conditions, which occur from September through November and bring hot dry weather and no rainfall. It is expected that the peak use of the reservoir, and consequently the highest water levels, will occur during January through March. The weather pattern during this period of the year typically results in winds from the west, generating wind-induced waves away from the upstream embankment of the dam. 2.1.6 Upstream Slope Protection The upstream slope of the embankment section must be protected against destructive wave action. Rock riprap placed on the sloping surface is typically the most economi- cal method of protecting slopes from wave forces. Since a sizeable quantity of rock will be generated during construc- tion of the shell of the dam, riprap has been selected as the logical choice of material for upstream slope protection. We have evaluated the slope protection requirements using the United States Corps of Engineers criteria outlined in the Coastal Engineering Research Center's "Shore Protection Manual," 1973 edition. Project No. 59185V-DSOl Woodward4lyde Consultants Assuming a design wave height of 2.2 ft, the recommended rock size is on the order of 175 lb for a mini- mum thickness of 30 in., measured normal to the slope face. An equivalent well-graded rock zone having at least 50 percent material larger than 175-lb stone would be an accept- able alternate. We have, therefore, recommended the follow- ing gradation for the outer 8 ft of slope, measured horizont- ally from the finish slope face. Rock Weight (lb) Nominal Diameter (in.) Percent Smaller Than 625 22 80-100 175 13 O-50 40 8 O-50 Since the reservoir will be operated at various water surface levels, the outer layer of riprap slope protec- tion extends along the entire surface of the upstream embankment. 2.2 SEEPAGE 2.2.1 Seepage through the Embankment Figure 2.1 shows the flow net for steady seepage through the dam under the full operating reservoir (Eleva- tion 594.5 ft). Since Zone 1 (shell section) will be at least 100 times more permeable than Zone 2 (impervious core) , only the flow net through Zone 2 is shown. 44 Project No. 59185V-DSOl WoodwardGyde Consultants Furthermore, the flow net is drawn for a homogeneous core . having the same horizontal and vertical coefficient of permeability. In practice, because the dam is compacted in horizontal lifts, the average horizontal permeability is generally larger than the vertical. Therefore, a more accurate estimate of the seepage conditions within the dam can be made by assuming that the horizontal coefficient of permeability of the core is nine times that of the vertical. The flow net (Fig. 2.2) was prepared using this assumption. This figure represents the seepage condition for the maximum section of the dam at Station 16+80. Simi- lar flow nets were drawn for eight other sections at an approximate spacing of 50 ft along the dam. The seepage volume was then computed from those flow nets using the following values of permeability coefficients: KV = 4~10~~ ft/min. Kh = 9Kv = 3.6~10~~ ft/min. The computed seepage volume was 643 gal/day for steady seepage through the embankment under the full reservoir at Elevation 594.5 ft. Figure 2.3 shows a flow net for steady seepage through the embankment having the water level at Elevation 575.0 ft. This is a typical flow net for a partially-filled 45 Project No. 59185V-DSOl WoodwarxKlyde Consultants reservoir. The seepage volume will, of course, be less than that mentioned above for the full reservoir condition. 2.2.2 Seepage through the Foundation To estimate the rate of seepage loss through the foundation, it was assumed, based on the geologic data, that the zone of fractured rock extends to a depth of 40 ft below surface of the the highly-weathered overburden. A flow net was prepared for this condition (Fig. 2.4). This net is very approximate because it assumes a homogeneous average permeability condition for the foundation. Using a flow net similar to that shown in Fig. 2.4 for various dam sections, and assuming an average permeabil- ity coefficient of 1~10~~ ftfmin., the underseepage through the dam foundation was estimated to be on the order of 700 gal/day for the maximum reservoir level at Elevation 594.5 ft. The combined estimated seepage through the embank- ment and the foundation is approximately 1,350 gal/day. The drain collector pipes, the collector sump, and the pump system have been designed for this design capacity. The system, however, can handle a considerably la~rger flow by activating the pump as frequently as necessary. 46 Project No. 59185V-DSOl WoodwardGlyde Consultants 2.2.3 Porewater Pressure Distribution - Steady Seepage Condition Figure 2.5 shows equipressure lines for the dam under a steady seepage condition with the full reservoir at Elevation 594.5 ft. This figure was prepared from the flow net (Fig. 2.2) for core Kh = 9Kv. A similar drawing (Fig. 2.6) shows the equipressure lines for steady seepage for a partially-filled reservoir having a water level at Elevation 575.0 ft. 2.2.4 Drawdown Condition The distribution of porewater pressure within the embankment following a rapid drawdown of the water level from the full reservoir (Elevation 594.5 ft) to the empty reservoir (Elevation 550.0 ft) was studied. Figure 2.1 shows the flow net for the drawdown conditions; Fig. 2.8 illustrates the equipressure lines following the rapid drawdown of the reservoir. 2.3 INSTRUMENTATION 2.3.1 Piezometers Pneumatic-type piezometers will be installed at five locations for monitoring performance of the chimney drain and the pressure relief wells. Three piezometers will be placed at separate locations at the base of the chimney 47 Project No. 59185V-DSOl Woodward-Clyde Consultants drain, and two piezometers'will be placed in 35-ft deep wells similar to those installed on the line of pressure relief wells. These two wells will be located at low points in the valley about 50 ft downstream of the relief wells. The lower 30 ft will be filled with pervious sand backfill and the upper 5 ft will be sealed with tamped bentonite. The pneumatic piezometer tips will be placed in the pervious sand backfill. Leads for all piezometers will be placed in specially prepared and backfilled trenches leading to the outlet structure, where the leads will connect to a control box on the wall. 2.3.2 Deformation Monitoring Monuments On the crest of the dam a line of concrete nonu- ments 6 ft deep, 6 in. in diameter, and containing a rein- forcing bar capped with a brass reference bolt will be installed to monitor vertical and horizontal movements, as well as lengthening or shortening between monuments. The monuments will be installed at 100 ft on centers in a straight line near the downstream edge of the crest of the dam. 2.4 STABILITY ANALYSIS The stability of the slopes of the proposed dam was evaluated on a digital computer, using the limiting 48 Project No. 59185V-DSOl WoodwarxbClyde Consultants equilibrium analysis procedure, based on the simplified Bishop method of slope stability analysis (method of slices). This procedure is an effective stress method of analysis. The soil properties used in the computations were selected based on the laboratory test results, and on our experience and engineering judgment. The design values were as follows: (a) (b) (c) (d) case was Random zone shell (Zone 1): Saturated unit weight Dry to moist unit weight Effective cohesion, c' Effective friction angle, 8' Impervious core (Zone 2): Saturated unit weight Effective cohesion, c' Effective friction angle, 0' Chimney drain (Zone 3): Moist to saturated unit weight Effective cohesion, c' Effective friction angle, 0' Foundation weathered rock: Unit weight Effective cohesion, c' Effective friction angle, 0' 120 lb/cu-ft 110 lb/cu-ft 0 34 to 40 degrees 120 lb/cu-ft 240 lb/cu-ft 26 degrees 110 lb/cu-ft 0 30 degrees 150 lb/cu-ft 0 40 degrees The distribution of the pore pressure for each computed from the equipressure lines applicable to 49 Project No. 59185V-DSOl Woodward.Clyde Consultants that particular case. From the equipressure lines, piezo- metric surfaces were developed for input in each analysis run. The cases analyzed and the safety factors computed are summarized below: (a) Full-Reservoir Condition - The stability of the upstream and downstream slopes of the dam were analyzed under the full-reservoir condition. Figure 2.9 shows the centers for three trial circles used for stability calculations of the upstream slope. For each center, deep and shallow trial failure circles were selected by varying the radius of the circle. The deepest circles were tangent to the bedrock. The computed safety factors for the three most critical circles (a deep, a shallow, and a mid-depth circle) are shown on the figure. The corresponding safety factors are 2.6, 1.5, and 2.0, respectively. These values correspond to a friction angle of 34 degrees for the shell material. To demonstrate the influence of an increase in friction angle of the shell on the computed safety factor, additional computations were made using fl' = 38 degrees and JJ' = 40 degrees for the shell material. The results for the critical deep-seated circle are shown on Fig. 2.9. Figure 2.10 shows similar results for the downstream slope under the full-reservoir condition. When the friction angle of the shell material was assumed 31 degrees, the lowest safety factor for the deep-seated circle was 2.0; for the near-surface circle it was 1.7; and for a mid-depth circle it was 1.9. The results of alternate computations for shell pI' = 38 and 40 degrees are also shown on the figure. 50 Project No. 59185V-DSOl Woodward-Clyde Consultants (b) Partial Pool Condition - Stability of the upstream slope for a partially-full reservoir (pool ,level at Elevation 575.0 ft) was analyzed. The results of the analysis for the three most critical failure circles are shown in Fig. 2.11. The computed safety factors for these three failure surfaces were 1.8, 1.8, and 1.9 for the conservative shell material properties of C’ = 0 and 8' = 34 degrees. The change in the reservoir level from Elevation 594.5 to 575.0 ft did not appreciably change the safety factor of the downstream slope from those shown on Fig. 2.9 for the full reservoir case. (c) Drawdown Condition - The effect of rapid drawdown of the reservoir from maximum pool level (Elevation 594.5 ft) to Elevation 550.0 ft was evaluated assuming only very limited drainage of the upper sections of the core during the period of drawdown. The computed safety factors for critical circles (Fig. 2.12) were 2.2 for a deep-seated circle, and 2.1 for a shallow circle. (d) Earthquake Condition - The effects of earthquakes on the stability of the embankment were investigated by applying a horizontal acceleration of O.lg to 0.15g at the centroid of each slice. The results of this pseudo- static analysis for critical cases for the upstream and the downstream slopes, with full reservoir condition, are shown on Figs. 2.9 and 2.10; the results for a critical case for the partial pool condition are shown on Fig. 2.11. It may be seen that application of a horizontal acceleration on the order of O.lg reduces 51 Project No. 59185V-DSOl Woodward-Clyde Consultants the safety factors, but even the lowest computed value in each case is still acceptable as safe for seismic conditions. The pseudo-static method of analysis used in case (d) above is an approximate method of seismic stability evaluation. Furthermore, average embankment accelerations on the order of O.lg to 0.15g correspond to distant earth- , quakes for this dam site. In our opinion, the pseudo-static method is not suitable for use in connection with higher ground acceleration levels associated with postulated seismic events at nearby sources, such as the Rose Canyon fault. For these cases, a rigorous dynamic analysis would be more appropriate. However, based on the available information regarding the history of performance of dams during earth- quakes, such detailed studies for small dams, which have high safety factors under static conditions and low proba- bility of liquefaction, are not warranted. A summary of a detailed review of performance of dams during earthquakes by Seed, Makdisi, and others (2) (3) (4) was published in the bulletin of the Earthquake Engineering Research Center of the University of California, (5) Berkeley, June, 1979 . Excerpts from this report: "Virtually any well-built dam on a firm foundation can withstand moderate earthquake shaking with maximum acceleration of about O.Zg, with no detrimental effects. . . . there is a marked difference between the seismic resistance of dams constructed of clayey soils and those dams constructed of saturated sands or other noncohesive soils. For example, no failures have been 52 Project NO. 59185VODSOl Woodward43yde Consultants reported in dams built of cZayey soils, even under extremely strong earthquake shaking conditions (accel- erations of 0.35g to 0.8g and 8.25 magnitude). All reported cases of complete failures OF embankment failures have involved dams constructed primarily with saturated sand shelZs OF on saturated sand foundations.” In our opinion, neither the shell rockfill nor the impervious clayey core of the dam are prone to liquefaction: since the chimney drain will not be saturated, it too will be safe against the danger of liquefaction. Therefore, a catastrophic failure caused by an earthquake is highly improbable for the proposed dam. But, we estimate that in the event of the occurrence of the maximum probable earth- quake (magnitude 6.8), the dam crest might settle as much as 1 ft. The design provides for ample freeboard for such an unlikely eventuality. 2.5 SPILLWAY 2.5.1 Hydrology The watershed upstream of the storage reservoir is approximately 26 acres in total size, of which approximately 9 acres are covered by the impounded water surface at the maximum operating pool level. The remainder of the watershed consists of relatively steep side slopes that have little or no surface depressions or ground cover to impede the downward progress of storm runoff. The soil type exposed over much of the surface is such that little infiltration can occur, 53 Project No. 59185V-DSOl and would be classified as'a type "D" soil when using the Soil Conservation Service criteria. The time of concentra- tion for storm runoff is estimated to be on the order of 5 min. Design flood flows have been based on the Rational formula, which is considered most appropriate for small watersheds (less than 0.5 square miles). A runoff coeffi- cient of 0.85 has been selected for design. The rainfall intensity selected for design is the "probable maximum precipitation" (PMP) associated with a "worst condition" 5-min. precipitation. The San Diego County Department of Sanitation and Flood Control maintains approximately 120 precipitation gage stations throughout the County (Fig. 2.14). The State Department of Water Resources also analyzes some of these precipitation records and publishes short-duration precipi- tation frequency data for several of the recording rain gages in the area. For our precipitation data, we have selected four stations listed in the Department of Water Resources publication, Bulletin 195, entitled "Rainfall Analysis for Drainage Design, Volume I, Short-Duration Precipitation Frequency Data," dated October,~ 1976. The stations selected were: Escondido Park Hill, Encinitas, Oceanside Pump Plant, and Fallbrook, which correspond to the recording rain gage numbers 183, 541, 195, and 184, respectively 54 Project No. 59185V-DSOl Woodward-Clyde Consultants (Fig. 2.14). Our interpretation of this data indicates that a 5-min. probable maximum precipitation may amount to 1.17 in. of rainfall, corresponding to an equivalent rainfall intensity of 14 in/hr. This would result in a probable maximum flood equal to 310 cu-ft/sec. It should be noted that this is a rather conservative value because reservoir storage has not been subtracted from this design flood flow. Additionally, the longer duration precipitation patterns, which would produce a higher total volume of runoff, have correspondingly lower precipitation intensities. In view of the diverse opinions associated with various approaches to evaluating the probable maximum flood, it is our opinion that a spillway design flood of 310 cu-ft/ set is a rather conservative and reasonable design for the storage reservoir. 2.5.2 General Criteria The purpose of a spillway is to release storm waters, preferably automatically, so that the worst possible condition of flood flows cannot overtop and destroy the dam. Specifically, the spillway must have a sufficient capacity to allow adequate freeboard above the maximum design flood flow, and must be failsafe with regard to possible malfunc- tions that could render it inoperative. The type and location of the spillway were studied carefully in conjunction with the design of the embankment 55 Project No. 53185V-DSOl Woodward.Clyde Consultants section. The configuration of the topography of the site and the pool level requirements, as well as the legal impli- cations of discharging water over the saddle to the east, suggest placement of the spillway in the north ridge, near the right abutment of the dam. Various alternative spillway designs were studied. It appeared from this study that an economic and satisfactory design could be obtained by use of an ungated, broad-crested weir, which would allow free discharge over the ridge line to the north. Because of the requirements for an access road from Ranch0 Santa Fe Road extending up the north ridge line, we have carried flood flows under the roadway through two corrugated metal arch pipes. The roadway is at an elevation such that if both corrugated metal pipes were to become clogged, and the culvert headwall were to impound flood waters, the entire design flood could pass above the headwall over the access roadway without impairing the hydraulic performance of the spillway structure. 2.5.3 Spillway Details The spillway consists of a 35-ft long, broad-crested weir. The weir is l-1/2 ft wide, and projects 1 ft above the approach and discharge aprons. The discharge channel converges at a constant 12-l/2-degree angle, both upstream and downstream of the weir. A headwall with two corrugated 56 Project No. 59185V-DSOl WoodwardXlyde Consultants metal arch pipes, about 36-l/2 ft downstream of the weir, carries flood flows under the access roadway, ind discharges the flow into a lower discharge channel and away from the drainage basin. Appropriate concrete cut-off walls are used as necessary on concrete slabs , and all construction joints utilise 6-in. rubber waterstops. All concrete sections utilize sufficient reinforcing steel to maintain the inte- grity of the spillway and aid in holding down the discharge apron during high velocity flow conditions, which could tend to pull up the slab. Subsurface drain conduits were placed along both edges of the discharge channel to dissipate uplift pressures induced by high-velocity flows impinging on imperfections at construction joints, which might penetrate the rubber waterstop. A subsurface drain is placed 3 ft downstream from the weir for the same purpose. The spillway section, including all components and structures, will be founded in cut weathered but stable rock. The discharge channel drops away from the weir at a gradient of 15 percent to set the downstream corrugated metal arch pipe inverts low enough to allow the entire design flood to pass over the concrete headwall if necessary. This steep slope produces supercritical flow conditions downstream of the weir for the lower flow rates. For all but the smallest flow conditions, we expect a hydraulic jump 57 Project No. 59185V-DSOl WoodwardClyde Consultants to occur and progress upstream. For the maximum design flood of 310 cu-ft/sec, we expect that the hydraulic jump will extend approximately 25 ft upstream of the headwall of the culverts. Lower flow intensities will develop correspond- ingly shorter jump distances. We estimate that all flows passing through the pipe culverts will have fully developed hydraulic jumps within the discharge channel, which will not adversely affect the performance of the weir. As mentioned previously, the spillway is also designed to carry the full design flood over the headwall in the event of blockage of the culverts. For this condition, we estimate that during the probable maximum flood the maximum depth of water over the weir would be 2.2 ft, which will result in a drowned jump with a diving jet. We estimate that a 10 percent reduction in the efficiency of the spillway for this condi- tion would occur, which is considered acceptable for this conservative design. 2.6 OUTLET WORKS 2.6.1 Operation Because of its use as a storage facility for the San Marcos County Water District Reclamation Project, design considerations for the outlet works included all necessary criteria for efficient utilisation as a storage reservoir, Project No. 59185V-DSOl WoodwardKtlyde Consultants as well as safety considerations for protection of the dam. Of primary concern is the requirement that provrsion be made for emptying the contents of the reservoir, and that the outlet works be capable of emptying at least one-half of the reservoir contents in seven days. For this reason, an outlet pipe through the base of the dam is necessary. Furthermore, the operational plan for the reclamation project necessitates a method of filling and withdrawing treated water from each reservoir. Water from the storage reservoir will be released by gravity; therefore, again, the pipe needs to be at the base of the dam. The inlet-outlet works have been designed so a single outlet conduit serves as an inlet-outlet pipe and outlet conduit for emptying the reser- voir. Valves are provided to allow pumping into the reservoir, or for withdrawing water for irrigation, or for emptying the reservoir if necessary. The inlet-outlet works are designed to provide access through either the intake structure or the outlet structure for inspection, if necessary. At the upstream end of the conduit, a hydraulically operated sluice gate is provided for emergency closure. The upstream sluice gate will be open most of the time, and all hydraulic control will be through valves at the downstream end ~of the conduit. 2.6.2 Outlet Conduit The outlet conduit consists of an 18-in. inside diameter asbestos cement pipe embedded in a 42-in. wide by 59 Project No. 59185V-DSOl Woodward-Clyde Consultants 42-in. deep concrete-filled trench founded in competent foundation materials under the embankment of the dam. The concrete encasement has been reinforced as necessary to reduce shrinkage and cracking of the concrete encasement, and to reduce movement associated with small changes in temperature. Also contained in the concrete encasement of the outlet conduit is the hydraulic tubing that controls the sluice gate at the inlet structure. Within the impervious core portion of the dam, four concrete seepage cutoff collars are provided to lengthen the seepage path and decrease the potential for piping along the outlet conduit. The outlet conduit is designed as a pressure conduit operating under a maximum head of approximately 81 ft at the maximum operating pool level. For these condi- tions, the maximum discharge capacity is approximately 49 cu-ft/sec. 2.6.3 Intake Structure The intake structure is a modification of the Soil Conservation Service hooded drop inlet structure, which consists of a rectangular riser extending approximately 14 ft above the invert of the conduit cast into the base of the riser. The structure measures approximately 17-l/2 ft from base to top; approximately 8-l/2 of the 17-l/2 ft will be buried below the finish ground surface. The inlet tower is 60 Project No. 59185V-DSOl Woodward-Clyde Consultants to be located approximately 5 ft above the lower portion of the channel bottom to allow for a drainage bypass during construction. Furthermore, the inlet tower is situated approximately 5 ft upstream from the furthest upstream embankment toe, to reduce any adverse effects associated with soil creep in the outer portion of the embankment. Upon completion of grading in the vicinity of the inlet tower, the tower will be approximately 17 ft from the embank- ment face, and only 9 ft exposed above the surface of the compacted backfill. The top of the inlet riser is located at Elevation 550.0 ft, which corresponds to approximately 3.2 acre-ft of storage within the reservoir. This storage capacity assures continued operation without adverse effects of future silta- tion. Trash racks on the inlet tower have been located to reduce clogging with floating debris. The structure, includ- ing trash racks and grating, has been designed to accommodate full hydrostatic head associated with a maximum operating pool on the outside of the intake tower and atmospheric pressure inside. This condition assumes the trash racks and grating have become plugged, allowing the inlet tower to empty and subjecting it to downstream ambient pressure. Calculations indicate that 8-l/2 ft of embedment of the intake structure enables the tower to withstand a 0.5g seismic acceleration without adverse effects to the struc- ture. 61 Project No. 59185V-DSOl Woodward-Clyde Consultants All of the metal elements within the structure are stainless steel, galvanised after fabrication, or painted to reduce corrosion potential. 2.6.3.1 Intake Structure Sluice Gate An Armco heavy-duty sluice gate, Model 100-30 (or equal), will control the flow of water into and out of the intake structure. The gate is designed for seating heads up to 100 ft and unseating heads up to 30 ft. The gate size is 18 in. by 18 in. and the gate bolts to an 18-in. diameter, square flange, round opening wall thimble, which will be cast in the wall of the inlet structure. The gate will be the flanged back type with a rising stem. The seating faces will be made of stainless steel. Movement of the gate will be controlled by a hydraulic cylinder mounted on the intake structure wall, directly above the gate. The cylinder is actuated by a small hand pump situated in the metal building located on top of the sump at the toe of the dam. The hydraulic supply and return lines for the cylinder are 3/S in. diameter stainless steel tubing. The tubing will be cast in the intake structure wall and in the concrete encasement around the outlet conduit. The mounting bracket, stainless steel anchor bolts, stem guides, couplings, tubing, and fittings necessary for mounting and operating the hydraulic cylinder are provided by Armco upon request. 62 Project No. 59185V-DSOl Woodward-Clyde Consultants An emergency means for operating the sluice gate in the event of a hydraulic line rupture has been designed into the system. Stainless steel quick-disconnects will be teed off the hydraulic lines close to the hydraulic cylinder. A stainless steel ball valve will be placed in each hydraulic line between the hand pump and the cylinder allowing the lines to be shut off from the system. The quick-disconnects and ball valves will be secured to the intake structure wall next to the cylinder. The tubing will extend from the ball valves into the concrete wall and through the outlet conduit encasement to the sump house. The quick-disconnects, ball valves, and tubing within the intake structure will be protected from water-transported objects by a fabricated, galvanized metal cover bolted to the wall. To use the emergency system, a diver must carry a small hand pump into the intake structure and attach it to the quick-disconnects. The ball valves will then be closed, allowing the diver to operate the gate. 2.6.4 Outlet Structure The outlet structure is attached to the outlet conduit on the downstream side of the embankment and consists of a small valve house and an impact-type energy dissipator immediately downstream. The outlet structure is located 5 ft downstream of the furthest downstream embankment preparation; 63 Project MO. 59185V-DSOl Woodward-Clyde Consultants again, to reduce the adverse effects of soil creep within the outer shell of the embankment. The final graded surface in the vicinity of the outlet structure will be near Eleva- tion 518 ft. The outlet structure has been designed to serve a triple purpose: as an energy dissipating device, as a chamber housing valves for the necessary operations of the reclamation facilities, and as a sump for collecting seepage and returning it back into the reservoir. The energy dissi- pator is a standard impact type utilizing a vertical baffle, which absorbs the direct impact of high velocity flows through the pressure conduit. The structure requires no tailwater for energy dissipation. However, tailwater com- pletely submerging the outlet pipe will improve the perform- ance, providing a smooth downstream water surface. Riprap protection will be placed downstream from the structure to further protect against erosion. Downstream of the riprap, an 8-ft wide channel sloping at 3 percent will be constructed to carry discharge waters down the valley. 2.6.4.1 Outlet Sump System A concrete outlet sump will be located directly upstream from the energy dissipator and will be constructed integrally with the energy dissipator. The sump will serve as a collection basin for seepage water discharging from two 6-in. diameter subdrain lines. In addition, the sump will 64 Project No. 59185V-DSOl WoodwardXXyde Consultants house the 18-in. diameter outlet pipe and the associated flanges and butterfly valve: the 12-in. diameter plug valve and pipe, which are connected to the treatment facility: and a small 2 ft by 2 ft by 1 ft sump in which the suction line for a centrifugal pump will be placed. The pump will trans- fer seepage water back to the reservoir through a 3-in. diameter galvanised iron pipe. An 8 ft by 8 ft by 8 ft steel building will be placed on the concrete slab that forms the top of the sump. The steel building will house the gear operators for the valves, the centrifugal pump and electric motor, and a float level pump switch. A 30-in. diameter manhole will provide access through the concrete floor slab of the steel building to the sump. The opening is large enough to allow any individual piece of the plumbing system to be removed from the sump. The steel building will also enclose the quick connect terminals of the hydraulic lines to the sluice gate cylinder and the terminal box for the embankment and founda- tion piezometers. The individual components of the sump and plumbing are discussed below. 2.6.4.2 Sump The inside dimensions of the sump are 6 ft 10 in deep by 8 ft 0 in. wide by 5 ft 6 in. high. There will be a 65 Project No. 59185V-DSOl WoodwatxbClyde Consultants small 2 ft by 2 ft by 1 ft'deep sump poured monolithically with the bottom of the larger sump. The suction line from the pump, the suction line check valve, and the pump switch float will be located in this small sump. Locating the float and suction line in this small sump allows the water level within the large sump to be drawn down below the bottom slab, providing a dry room in which repairs to equip- ment can be made. The two chimney subdrain lines will enter the upstream wall of the sump at a point 4 ft 4 in. above the sump bottom (measured to the invert of the drain pipes). The invert of a 6-in. diameter hole in the downstream wall of the sump will be 4 ft 0 in. above the sump bottom. This hole will act as an emergency overflow drain allowing water to spill into the energy dissipator if the pump fails. The pump float will be adjusted so that the water level within the sump will not exceed a height of 3 ft 6 in. above the sump bottom. A small water-activated alarm will be attached to the wall of the sump at a point 3 ft 9 in. above the sump bottom. The alarm will be located on the downstream wall near the emergency drain and will activate a buzzer in the treatment plant. It is expected that approximately 1,340 gal/day will enter the sump through the two subdrain lines when the reservoir is operating at full pool. The sump will hold 66 Project No. 59185V-DSOl Woodward-Clyde Consultants approximately 1,340 gals at the maximum 3 ft 6 in. operating level. The pump will empty the sump approximately once every 24 hours. If a malfunction occurs in the pumping system, and assuming a flow rate into the sump of 1,340 gal/day, it would take approximately 3-l/2 hours for the water to reach the emergency drain from the 3 ft 6 in. level. The emergency alarm would be activated approximately l-3/4 hours prior to the water reaching the emergency drain. The invert of the subdrain lines is located 4 in. above the invert of the emergency drain. Therefore, back pressure in the subdrain lines if the pump malfunctions is not likely. A small flap gate will be provided over the emergency drain to keep rodents and foreign matter from entering the sump. 2.6.4.3 Pump System The selected pump is a self-priming, centrifugal pump operated by a 5-hp, three-phase motor manufactured by Peabody Barnes (or equal). The pump and motor are an inte- gral unit. The pump has 2-in. diameter suction and exhaust lines, and will be activated by a float level switch. The float mechanism consists of a brass rod with .two adjustable stops, which contact a switch as the rod moves up and down due to the action of a brass float. The pump and pump switch will be mounted to the concrete slab that forms the top of the sump. 67 Project No. 59185V-DSOl Woodward-Clyde Consultants The pump will lift water approximately 8 ft through a 2-in. diameter pipe from the bottom of the sump to the pump, and then pump the water over the crest of the embankment into the reservoir. The water will travel through approximately 400 ft of 3-in. diameter galvanized pipe, and will rise approximately 80 ft from the pump to the reservoir crest. Under a head of 105 ft, the pump is capable of delivering 100 gal/min.; approximately 14 ft of head is lost in friction through 408 ft of pipe. The water can, therefore, be lifted approximately 91 ft at 100 gal/min. At a rate of 100 gal/min., approximately 13 min,. will be required to empty 1,340 gal accumulated in the sump; according to our estimates, the sump will be emptied every 24 hours. Due to the uncertainties inherent in estimating seepage losses from the reservoir, it is prudent to use the chosen pump, even though a smaller pump could probably handle the job adequately. Head losses within the system will increase with age, and the 2-in. pump with 5-hp motor has sufficient reserve capacity to handle increasing head losses and seepage losses larger than those expected. The suction line will be a 2-in. diameter galvan- ised pipe and will have a spring-actuated che~ck valve at the bottom of the sump. The bottom stop on the float switch will be adjusted so that water will always be standing above the check valve, but will allow water to be pumped down slightly lower than the bottom of the large sump. 68 Project No. 59185V-DSOl WoodwardClyde Consultants The electric pump motor will require 220 volt service. 2.6.4.4 Valves Two valves, built into the 18-in. and 12-in. pipes in the sump, will be controlled by manual gear operators located in the metal building above. Flow through the 18-in. diameter outlet conduit will be controlled by an 18-in. AWWA butterfly valve, Model 27F-BRB, manufactured by Crane (or equal). The valve has a flanged body and molded in Buna N seat, bronze disc, and stainless steel stem. The valve weighs 420 lb, and is designed to withstand a 150 lb/sq-in. pressure differential. The operator extension will extend from the valve through a 6-in. diameter hole in the concrete slab to a manual gear operator, which bolts to the top of the extension. The internal stem extension and gear operator are supplied by Crane with the valve. The stem extension will be housed in a 3-in. diameter pipe with flanged ends. The outside pipe and flanges have to be fabricated to fit the valve and gear operator. Flow to the treatment plant will be controlled by a 12-in. plug valve, Dezurik Series 100 (or equal). This valve will have a maximum working pressure of 175 lb/sq-in. The valve will have an extension and gear operator similar to that described above for the butterfly valve. 69 Project No. 59185V-DSOl WoodwarxbClyde Consultants 2.6.4.5 Flanges and Pipe The outlet conduit will be an 18-in/inside diam- eter asbestos cement pipe extending from the inlet tower to the downstream concrete sump. A cast iron ring-tite-to-flange adaptor will be cast in the wall, and all the pipes and flanges within the sump will be 18-in. or 12-in. diameter by l/2-in. wall thickness steel pipe. The flanges used to connect the valves and pipe sections will be Keflex Type 151-1215 (or equal), with maximum working pressures of 150 lb/sq-in. The flexible flanged couplings are designed for a total axial traverse of 5/0 in. (l/2 in. compression, l/8 in. extension), a total lateral movement of l/8 in. (l/16 in. each side of centerline), and an angular offset of 3-l/2 degrees maximum. A short section of 18-in. diameter outlet pipe that has the flange on the inside of the sump will be cast in the downstream wall. An Armco medium-duty flap gate (or equal) will be provided over the outlet conduit. The flap gate will keep small rodents, birds, etc., from entering. A short section of 12-in. diameter pipe that has flanges on each end will be cast in the north wall of the storage reservoir sump. 2.6.4.6 Miscellaneous Items The metal building housing the valve operators, pump, and other equipment will be an Armco Tee-Line Type LS-1F 70 Project No. 59185V-DSOl WoodwatxbClyde Consultants all steel building having a single slope roof (l-l/2-in. in 8-ft pitch) and a single steel door. Windows are not pro- vided, thus reducing attraction to vandals. The building will be factory painted in a suitable attractive color acceptable to the owner. The walls of the impact basin will be provided with a 6-ft high chain link fence to protect against persons wandering around or falling into the 6-ft deep steep-walled basin. The area around the sump and energy dissipator will be graded to provide sufficient access and parking area for maintenance personnel. 71 FLOW NET FOR STEADY SEEPAGE CORE Kh = Kv APPROXIWATE SCALE: 1" = 50' I FLOW NET FOR STEADY SEEPAGE LA COSTA STORAGE RESERVOI? DRAWN BY: mr k CHECKED BY: &, PROJECTNO: 59185V-DS01 DATE: 8-25-79 1 FlO"RE MO: 2.1 WOOOWARO-CLYDE CONSULTANTS ELEVATION 594.5' v FLOW NET FOR STEADY SEEPAGE CORE Kh = 9Kv FLOW PJCT FOR STEADY SEEPAGE LA COSTA STORAGE RESERVOIR I DRAWN BY: mrk CHECI(EDBY:LL. PROJECTNO: 59185V-DSOl DATE: 8-25-79 FlG”RE Iyo: 2.2 WflF!?WI\RD-CLYDE CONSULTANTS FLOW NET FOR STEADY SEEPAGE - PARTIAL POOL CORE Kh = 9X" APPROXIMATE SCALE: 1” = 50’ FLOW NET FOR STEADY SEEPAGE - PARTIAL POOL LA COSTA STORAGE RESERVOIR DRAWNBY: mrk CHECI(EDBY:C~~ PRO.JECTNO:~V~~~V-DSO~ DATE: 8-25-79 FlGURL Na2.3 WOOOWARO-CLYDE CONSULTANTS FLOW NET FOR SEEPAGE THROUGH THE FOUNDATION ELEVATION 594.5' \,\ ELEVATION 525.O'g I tl APPROXIMATE SCALE: 1 I( = 50’ FLOW NET FOR SEEPAGE THROUG~I THE FOUNDATION LA COSTA STORAGE RESERVOIR I DRAWN BY: mr k CHECKED BY: LL PR~JECTNO:S~~B~V-DSO~ DATE: 8-31-79 FlO”RE no: 2 .4 WOOOWARO-CLYDE CONSULTANTS ELEVATION 594.5' EQLJIPRESSLJRE LINES FOR STEADY SEEPAGE CORE Kh = 9Kv . APPROXIMATE SCALE: 1" = 50' I EQUIPRESSURE LINES FOR STEADY SEEPAGE LA COSTA STORAGE RESERVOIR 1 m~rms":mrk CHECKED BY:- PR~JECTNO:SV~ESV-DSO~ DATE: 8-25-79 F,C”RE No: 2.5 WOOOWAR0-CLYDE CONSULTANTS , ELEVATION 575.0' EQUIPRESSURE LINES FOR PARTIAL POOL CORE Kh = 9K, APPROXIMATE SCALE: 1 It = 50’ EQUIPRESSURE LINES FOR PARTIAL POOL LA COSTA STORAGE RESERVOIR DRAWNBY: mrk CHECKEDBY:- P,~OJECTNO: 59185V-DSOl DATE: 8-25-79 1 FlO"RE NC% 2. fj WOOOWARO-CLYDE CONSULTANTS ELEVATION 594.5' - FLOW NET FOR RAPID DRAWDOWN CORE Kh = 9Kv APPROXIMATE SCALE: 1" = 50' FLOW NET FOR RAPID DRAWDOWN LA COSTA STORAGE RESERVOIR DR~NBY: mrk CHECKEDBV:~ PROJECTNO: 59155V-DSOl DATE: E-25-73 F,C”RE NO: 2.7 WOOUWARO-CLYDE CONSULTANTS EQUIPRESSURE LINES FOR RAPID DRAWDOWN CORE Kh = 9Kv APPROXIMATE SCALE: 1" = 50' EQUIPRESSURE LINES FOR RAPID DFZAIJDOWN LA COSTA STORAGE RESERVOIR DRMNBY: mrkl CHE~~~~BY:- 1 PR~JECTHO:~V~~SV-DSO~ DATE: 8-25-79 1 FIGURE NO: 2.8 WOOOWARO-CLYOE CONSULTANTS SHELL C'=0,&34' F.S. = 2.0 F.S. = 1.2 with O.lg hor. F.S. = 2.4 F.S. = 1.4 with \ SHELL ~~=0,&38~ SHELL C'=O SHELL C'=O O.lg F.S. = 1.1 with 0.15g \\ SHELL C'=O, @'=40" F.S. = 1.5 with O.lg F.S. = \\ 1.2 with 0.15g \ \ \ \ 9 \\ \\ \\ ti CD u- - - WATER SURFACE ELEVATION = 594.5' \ \ FULL RESERVOIR CONDITION SEE FIGURE 2.13 FOR KEY APPROXI.MATE SCALE: 1” = 50’ UPSTREA"! SLOPE STABILITY FULL RESERVOIR CONDITION LA COSTA STORAGE RESEREQI DRAWN BY: mrk CHECKED BY: & PR~JECTNCI:~V~~SV-DS~~ DATE: 8-31-79 1 FlG”RL No: 2.9 WOOOWARO-CLYDE CONSULTANTS FULL RESERVOIR CONDITION SEE FIGURE 2.13 FOR KEY SHELL C'=O, +34O F.S. = 1.7 F.S. = 1.3 With O.lq Horiz. SHELL C'=O, &34' 1.5 with O.lg her.' = 1.4 with 0.15g hor. F.S. = 1.2 with 0.2g hor. SHELL C'=O J&340 F.S. = 1.9 w SHELL C'=O, g&38' F.S. = 2.2 F.S. = 1.7 with O.lg hor. SHELL C'=O, J&40° F.S. = 2.4 F.S. = 1.9 with O.lg hor. WATER SURFACE ELEVATION = 594.5' APPROXIMATE SCALE: 1" = 50' I DOWNSTREAM SLOPE STABILITY FULL RESERVOIR CONDITION 1 LA COSTA STORAGE RESERVOIR ~!ubv~~~:rnrk CHECKEO BY: Lu 1 ~~o.m~o:59185V-DSOl~ DATE: 8-31-79 1 FlC"RE Im2.10 WOODWARD-CLYOE CONSULTANTS F.S. = 1.8 \ F.S. = 1.9 F-S- =1.2 with O.lg hor. PARTIAL POOL CONDITION ALL TRIALS ARE FOR SHELL C'=O, +34' WATER SURFACE ELEVATION = 575.0’ SEE FIGURE 2.13 FOR KEY APPROXIMATE SCALE: 1 " = 50’ UPSTREAM SLOPE STABILITY PARTIAL POOL CONDITION LA COSTA STORAGE RESERVOIR mmv~~~:rnrk CHECKED BY: GL- ~R~JECTNO:SV~~~V-DS~~ DATE: 8-31-79 FlGURENO: 2 .ll WOOOWARO-CLYUE CONSULTANTS , 7 F.S. = 2.1 SUDDEN DRAWDOWN CONDITION BOTH TRIALS ARE FOR SHELL C'=O, g&34' SEE FIGURE 2.13 FOR KEY WATER SURFACE ELEVATION = 545.0' / APPROXIMATE SCALE: 1 'I = 50' UPSTREAM SLOPE STABILITY SUDDEN DRAWDOWN CONDITION LA COSTA STORAGE RESERVOIR mww~w:mrk CHECKED BY: &/ PR~JECTNO:~~~~~V-DSOL DATE:~-31-79 1 FlG"REWcr 2.12 WnOtYARCl-CLYDE CONSIJLTANTS SOIL PARAMETERS USED FOR SLOPE STABILITY ANALYSES: SHELL - UPSTREAM SHELL - DOWNSTREAM IMPERVIOUS CORE CHIMNEY DRAIN FOUNDATION 75' C' B' (pcf) (psf) 120 0 34" to 400 110 0 340 to 400 120 240 26' 110 0 300 125 0 40" F.S. = FACTOR OF SAFETY DERIVED USING THE LIMITING EQUILIBRIUM ANALYSIS PROCEDURE BASED ON THE SIMPLIFIED BISHOP METHOD (METHOD 0~ SLICES) OF SLOPE STABILITY ANALYSIS. KEY TO SLOPE STABILITY FIGURES LA COSTA STORAGE RESERVOIR DRAWN BY: mrk CHECKED BY: b 1 PROJECTNO: 59185V-DS04 DATE: 8-31-79 1 Flo"RENoz2.13 WOOOWARO-CLYDE CONSULTAWTS Project No. 59185V-DSOl REFERENCES Woodward42yde Consultants (1) Moore, D.W., 1972, Offshore extension of the Rose Canyon fault, San Diego, California, in Geological Survey Research, 1972: U.S. Geologica Survey Pro- fessional Paper 800-C, U.S. Government Printing Office, P. 113-116. (2) Serff, N., Seed, H.B., Makdisi, F.I., and Chan, C.Y., 1976, Earthquake induced deformations of earth dams: Report No. EERC76-4, Earthquake Engineering Research Center, University of California, Berkeley. (3) Makdisi, F.I., and Seed, H.B., 1978, Simplified pro- cedure for estimating dam and embankment earthquake- induced deformations: Journal of Geotechnical Engineer- ing Division, ASCE. (4) Seed, H.B., 1979, Rankine lecture on failure of dams during earthquakes, London and University of California, Berkeley. (5) EERC News, 1979, Earthquake Engineering Research Center, University of,California, Berkeley, v. 3, No. 2. Project No. 59185V-DSOl BIBLIOGRAPHY Woodward-Clyde Consultants Allen, C.R., St. Amand, P., Richter, C.F., and Nordquist, J.M., 1965, Relationship between seismicity and geologic structure in the southern California region: Bulletin of the Seismological Society of America, v. 55, no. 4, p. 753-797. Ellis, A.J., and Lee, C.O., 1919, Geology and ground waters of the western part of San Diego County, California: U.S. Geological Survey Water Supply Paper 446, p. 321. Idriss, I.M., 1978, Characteristics of earthquake ground motions: ASCE Specialty Conference, Earthquake Engineering and Soils Dynamics, v. 3, p. 1151-1266. McEuen, R.B., and Pinckney, C.J., 1972, Seismic risk in San Diego: San Diego Society of Natural History, Transactions, v. 17, p. 33-62. Moore, G.W., 1972, Offshore extension of the Rose Canyon fault, San Diego, California, in Geological Survey Research, 1972: U.S. Geological Survey Professional Paper 800-C, U.S. Government Printing Office, p. 113-116. Moore, G.W., and Kennedy, M., 1975, Quaternary faults at San Diego Bay, California: U.S. Geological Survey Journal Research, v. 3, p. 589-595. Simmons, Richard S., 1977a and b, Seismicity of San Diego, 1934-1974: Bulletin of the Geological Society of America, v. 67, no. 3, p. 809-826. Wiegand, J.W., 1970, Evidence of a San Diego Bay-Tijuana fault: Association of Engineering Geologists Bulletin, v. 7, p. 107-121. Project No. 59185V-DSOl WoodwardClyde Consultants GLOSSARY Active Fault - A geologic fault on which there has occurred significant subsurface earthquake activity, or any surface ground breakage, within the last 10,000 years. (Note: Other definitions of active fault exist; this definition is for the purpose of this study, but is consistent with other definitions. Alluvium - Unconsolidated detrital material deposited during comparatively recent geologic time by a stream or other body of running water. Aseismic - Said of an area not subject to earthquakes. Batholith - A large plutonic mass that has more than 40 square miles in surface exposure, and is composed predomi- nantly of medium to coarse-grained rock of granodiorite and quartz monzanite composition. Continental Borderland - That area of the continental margin between the shoreline and the continential slope with topo- graphically~complex features. Cretaceous Period - The period of time 136 to 65 million years ago. Disseminated - Said of a mineral deposit in which the minerals occur as scattered particles in rock. Fault Scarps - A steep cliff formed directly by movement along one side of a fault. Fault Set - A group of faults that are parallel or nearly parallel, and that are related to a particular deformational episode. Fault System - Two or more interconnecting fault sets. Fault Zone - A zone of related faults that commonly are braided and sub-parallel, but may be branching or divergent. It has significant width, ranging from a few feet to several miles. Gypsum - A mineral consisting of hydrous calcium sulfate. Jurassic Period - The period of time between 195 to 136 years ago. Project No. 59185V-DSOl Woodward-Clyde Consultants Lateral Fault - A fault along which there has been strike separation or movement predominantly parallel to the strike. Limonite - A general field term for a group of brown, amor- phous, naturally occurring hydrous ferric oxides whose identities are unknown. Lineaments - Straight or gently-curved, lengthy features of the earth's surface, frequently expressed topographically as depressions or lines of depressions. Lithified - The conversion of unconsolidated sediments into a coherent rock. Maximum Credible Earthquake - The maximum earthquake that appears capable of occurring under the presently known tectonic framework. Maximum Probable Earthquake - The maximum earthquake that is likely to occur during a loo-year interval. Magnitude - Magnitude is related to that energy which is radiated from the earthquake source in the form of elastic waves. Basically, magnitude is the rating of a given earth- quake related to the earthquake energy released in the hypocentral area, and is independent of the base of obser- vation since it is calculated from measurements on seis- mographs. It is expressed in ordinary numbers and decimals. Magnitude was originally defined by C.F. Richter as a logarithm (base 10) of the maximum amplitude of a seisno- graph at a distance of 62 miles (100 kilometers) from the focus. For other distances, or for instruments of other types, conversion to the standard is made. Meta - A prefix that, -igneous rock, when used with a name of a sedimentary indicates that the rock type has been metamorphosed. Dormal Fault - Vertical movement along a sloping fault surface in which the block above the fault has moved down- ward relative to the block below. Overburden - Topsoil, slopewash, alluvium, and residual clay. Plate Tectonics - Global tectonics based on an earth model characterized by a small number of large, broad, thick plates, each of which "floats" on some viscous underlayer in the mantle and moves more or less independently of the others. Project No. 59185V-DSOl Woodward-Clyde Consultants Pleistocene - An epoch of the Quaternary period, after the Pliocene of the Tertiary and before the Holocene, thought to cover the span of time approximately 11,000 and 3 million years ago. Potentially Active Fault - A fault that offsets Pleistocene materials, but for which offset of Holocene materials is lacking and for which seismic activity is nominal or absent. Propylitic - Hydrothermally altered andisite. Quaternary - The last 3 million years. Recent Displacements - Holocene displacement (less than 11,000 years ago). Residual Clay - Extremely finely divided clay material formed in place by the weathering of rock. Right Lateral Fault - A fault along which, in plan view, the side opposite the observer appears to have moved to the right. RQD - Total length of rock core greater than 4 inches in a core run, divided by length of core run times 100 (expressed as a percent). Sag Depression - An enclosed depression formed where active fault movement has closed topographic contours. Seismic Velocity - Rate of propagation of an elastic wave. Shallow Focus Earthquake - An earthquake whose focus occurs at a depth of less than 50 kilometers. Slopewash - Soil and rock material that is or has been transported downslope by mass-wasting assisted by running water not confined to channels. Spoil Pile - A pile of refuse material from an excavation. Strain Release - The release of strain, or the return of a body, to a pre-strain configuration. Sub-bottom Acoustic Profiles - A seismic reflection profile in which reflectors lie beneath the bottom of the ocean. Tertiary - The period of time between 65 and 3 million years ago.