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HomeMy WebLinkAbout91-2; Geotechnical Investigation Marisol Project; Geotechnical Investigation Marisol Project; 1992-02-21GEOTECHNICAL INVESTIGATION m MARISOL PROJECT 4519 ADAMS AVENUE to CARLSBAD, CALIFORNIA "* JOB NO. 92-1 M FEBRUARY 21, 1992 WESTERN SOIL AND FOUNDATION ENGINEERING, INC. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. PHONE 746-3553 AREA CODE 619 423 HALE AVENUE ESCONDIDO, CALIFORNIA 92O29 February 21, 1992 Mr. Stephen E. Brendle Laguna Associates c/o A.S.K. 120 Birmingham Drive, Suite 110 Cardiff-by-the-Sea, California 92024 Project: Job No. 92-1 Proposed Marisol Project 4519 Adams Avenue Carlsbad, California Subject: Report of Geotechnical Investigation Mr. Brendle: In accordance with your request, we have completed a geotechnical investigation for the proposed project. We are presenting to you, herewith, our findings and recommendations for the development of this site. The findings of this study indicate that this site is suitable for the proposed development provided that the special preparations and foundation recommendations presented in the attached report are complied with. If you have any questions after reviewing the findings and recommendations contained in the attached report, please do not hesitate to contact this office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, WESTERN SOIL AND FOUNDATION ENGINEERING, INC Vince Gaby, ProjectGeologl.st Dennis VG/DEZ:kw Attachments Distribution: CE 26676 GE 928 (4) Addressee GEOTECHNICAL INVESTIGATION MARISOL PROJECT 4519 ADAMS AVENUE CARLSBAD, CALIFORNIA Prepared For: MR. STEPHEN E. BRENDLE LACUNA ASSOCIATES C/O A.S.K. 120 BIRMINGHAM DRIVE, SUITE 110 CARDIFF-BY-THE-SEA, CALIFORNIA 92024 JOB NO. 92-1 FEBRUARY 21, 1992 WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 •» February 21, 1992 Page 1 m GEOTECHNICAL INVESTIGATION MARISOL PROJECT ,. 4519 ADAMS AVENUE CARLSBAD, CALIFORNIA *" INTRODUCTION AND PROJECT DESCRIPTION M *» This report presents the results of our geotechnical invest- igation performed on the above referenced site. The purpose of this investigation was to evaluate the existing surface and subsur- tm face conditions from a geotechnical perspective in order to provide ta recommendations for your proposed development. ,- The proposed project is the development of three, single-family *" residences, as submitted by you in preliminary form on the site """ plan included as part of and shown on Plate Number 1 of this *M report. A private drive will provide access to the dwellings from Adams Avenue. Retaining walls will be utilized in the construction _ of the roadway and dwellings. It is our understanding that the •" proposed dwellings will be one or two-story wood-framed structures. "* The foundations will be slab-on-grade with continuous and pad spread footings. A grading plan had not been prepared at the time of this writing. However, it is anticipated that the proposed grading will *• involve maximum cuts and fills on the order of 10 feet. •" Should any future development deviate significantly from our i^ understanding of the project as described above, we should be consulted for further recommendations. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 2 The site configuration and exploratory trench locations are shown on Plate Number 1. PROJECT SCOPE This investigation consisted of a surface reconnaissance coupled with a detailed subsurface exploration. Representative surface and subsurface samples were obtained from the site and returned to our laboratory for testing. An analysis of the field and laboratory data collected is submitted in this report. Specifically, the intent of this analysis was to: a) Explore the subsurface conditions to the depths that could be influenced by the proposed construction, b) Evaluate, by laboratory tests, the pertinent engineering properties of the various soil and rock stratigraphic units which could influence the development of this land, including bearing capacities, expansive characteristics and settlement potential, c) Develop soil engineering criteria for site grading, d) Determine potential construction difficulties and provide recommendations concerning these problems, e) Recommend an appropriate foundation system for the type of structures anticipated and develop soil engineering design criteria for foundation design. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 3 FINDINGS SITE DESCRIPTION: The property site is located 4519 Adams Street, in the City of Carlsbad, California. It can be found in the north central portion of grid B-6, page 14 of the Thomas Brothers Guide for San Diego County. The property is nearly rectangular in configuration and encompasses approximately 1.1 acres. It is bounded to the east by a single family residence, to the west by the Carlsbad Boat Club and to the south by Agua Hedionda Lagoon. Approximately 134 feet front Adams Street along the northern property line. The subject site is situated upon a southerly falling hillside. The topography is moderately steep to gently inclined. Elevations range from approximately 0 feet above mean sea level (M.S.L.) along the lagoon shoreline to 46 feet (M.S.L.) along Adams Street. The northern half of the property has been altered by minor grading. This is suggested by a large pad area in this portion of the site. In addition, a fill slope extends from Adams Street across the north property line. Drainage is by sheet flow into Agua Hedionda Lagoon. Water directed by a street culvert east of the property, crosses the eastern property line and flows along this boundary. This has resulted in the erosion of a narrow gully which intersects and then runs parallel to the eastern property line. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 4 No improvements were observed on site during our investigation. At that time, the majority of the property was covered by sparsely growing wild grasses. SUBSURFACE CONDITIONS: The project site is underlain by Quaternary age nearshore marine terrace sediments deposited on Eocene age sandstone. These units have been mapped by Weber (1982) as the Lindavista Formation and the Santiago Formation, respective- ly. These formational deposits are mantled by Holocene colluvium, recent beach deposits, and artificial fill. Each of these is described from oldest to youngest. SANTIAGO FORMATION: The Santiago Formation is represented on site by very pale gray to white slightly silty medium to very coarse grained sandstone. It is lithologically similar to Member B of the Santiago Formation as described by Wilson (1972). It is massively bedded, dense, and moderately well cemented. It is composed primarily of subangular grains of quartz and feldspar with minor lithic fragments. Within the sequence occur thin layered interbedded sandy clays and silts. These fine grained beds range in color from yellowish-gray to brown are very moist and stiff. LINDAVISTA FORMATION: On this site the Santiago Formation is unconformably overlain by beach/nearshore marine terrace deposits. These deposits are composed of brown to orangish-brown, fine to WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 5 medium grained sand. They are moderately well indurated, massively bedded and typically well cemented. The cement is ferruginous giving these deposits their orange coloring. In this area the Lindavista Formation is flat lying. However, it's basal contact with the Santiago Formation dips very gently to the southwest. COLLUVIUM: The formational sediments are mantled by colluvium which varies from 1 to 4 feet in thickness. For the purposes of this study the term colluvium is used to describe both in-situ developed soil as well as slope wash materials. It consists of very dark brown sandy clay to clayey sand. It is generally porous, and poorly consolidated. A sample of the clayey colluvium was returned to our laboratory to determine its expansive potential. Test results (Plate Number 9) indicate this material to have a medium expansion potential. BEACH LAGOON DEPOSITS: The southern one-third of the site is covered with recent beach and lagoon deposits. These consist of thinly bedded, silty to clean, fine, medium and coarse grained sands and sandy silt. The sands are gray to brownish-orange and the silts are very dark gray. These sediments are very moist to saturated and unconsolidated. In exploratory trench T-5 they extend beyond the limits of our investigation (Plate Number 7). WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 6 ARTIFICIAL FILL: Localized areas of artificial fill are present on the subject site. These areas are indicated on Plate Number One. Within the vicinity of our exploratory trenches the fill material ranges from 2 to 4 feet in thickness. It appears to be derived from the on-site formational and colluvial soils. It is composed of poorly compacted, clayey and silty sand. GROUNDWATER: Free groundwater was encountered in two of our exploratory trenches. These were in trenches T-4 and T-5 at a depth of approximately 8 and 7 feet, respectively. In addition, water infiltration was observed in trench T-4 at the contact between fill and formation. In this area and northward along the eastern boundary it is recommended that a subdrain be installed as described on Page 9 of this report. Fluctuations in the level and flow of groundwater may occur in this area depending on annual precipitation and irrigation. GEOLOGIC HAZARDS FAULTS AND SEISMIC HAZARDS: There are no known active or poten- tially active faults on or in the immediate vicinity of the project site. There are, however, several faults located in sufficiently close proximity that movement associated with them could cause significant ground motion at the site. The table below presents WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates February 21, 1992 Our Job No. 92-1 Page 7 the probable maximum earthquake magnitudes and accelerations anticipated at the site. These accelerations are based on the assumption that the maximum probable earthquake occurs on specific faults at the closest point on that particular fault to the site. SEISMICITY OF MAJOR FAULTS Fault Rose Canyon (Offshore) Elsinore San Jacinto San Andreas Distance (Miles) 8 22 40 66 Maximum Probable Magnitude (Richter) 6.0 - 7.0 L L 7.0 L 7.8 L 8.5 Probable Bedrock Acceleration* (a) 0.28-0.42 0.20 0.15 0.1 L= Local Magnitude *(From Schnabel and Seed, 1972). LIQUEFACTION: Saturated, poorly consolidated, well sorted, fine grained sands and silts will not exist under building pads if the grading operation is performed in strict accordance with the recom- mendations contained in this report. Therefore, it is unlikely that liquefaction would affect the site. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 8 LANDSLIDES AND SLOPE STABILITY: No evidence indicating the presence of deep seated landslides were observed on the project site. However, it is highly recommended that as-built inspections of all cut slopes be conducted by the Soil Engineer or Engineering Geologist during grading. We anticipate that the slopes proposed for this project will be stable if constructed in accordance with the recommendations contained in this report. No evidence suggesting the presence of geologic hazards that would preclude the development of this proposed project were observed in our exploratory trenches. We did, however, encounter poorly consolidated and expansive, near surface, soil material. Recommendations concerning these conditions are presented in the following sections of this report. During the grading operation, a Registered Geotechnical Engineer from our firm must inspect the site for adverse geologic conditions. RECOMMENDATIONS AND CONCLUSIONS SITE PREPARATION EXISTING SOIL: We recommend that any existing fill, topsoil, colluvium, and low density soil be removed to firm natural ground from beneath any proposed fill pad areas in their entirety, so that structures will be supported on firm material. Areas to receive WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 9 asphaltic or concrete pavements, slabs, driveways or sidewalks must be treated similarly. This soil may be replaced as a controlled fill recompacted to at least 90% of its maximum dry density. All deleterious materials and oversized debris encountered in this fill must be removed and legally disposed of off-site. Based on the findings of this study, the depth of removal will range from 2.0 to 5.0 feet. Deeper removals or an alternate foundation design may become necessary if the proposed construction extends south of the location of exploratory trench T-4. This is suggested by the absence of firm materials in trench T-5 (Plate Number 7) at a relatively shallow depth. Table I of this report presents anticipated removal depths in the area of our exploratory trenches. If groundwater is encountered during the removal and recompaction of the soil or difficulty is encountered in achieving a minimum of 90 percent relative compaction, then this office shall be consulted for further recommendations. It is anticipated that groundwater and/or extremely saturated soil may be encountered in the southern portion of the property. This would present difficulty in achieving a minimum of 90% relative compaction. In such cases it is recommended that rock may be used to support the earthmoving equipment and to provide a base on which to properly recompact soil fill material. The thickness and size of rock would be determined in the field by the Soil Engineer. As a preliminary estimate, a 2-foot thick layer of WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 10 6 to 8 inch minus rock would be placed in the bottom of the excavation. The rock should be placed in (1) foot maximum thick lifts. The voids in each lift should be completely filled with granular material and sufficiently watered as directed by the Soil Engineer prior to placement of the next lift. SUBDRAINS: If fills are proposed for canyon areas or drainage swales, a subdrain system shall be designed to alleviate potential groundwater problems. The system shall carry water legally off- site. These drains shall be placed in the center of the troughs created by the natural drainage swales at the impervious contact. The final determination for the location of the subdrains shall be made by the Soil Engineer during grading of the site. The subdrains shall consist of a trench at least 36 inches deep and 24 inches wide. The lower 24 inches of the trench shall be excavated into dense, natural soil material. The upper 12 inches will be installed in compacted fill. The drain shall have a minimum one percent gradient. A four inch diameter perforated pipe shall be placed in the trench with perforations down. The pipe shall be ABS schedule 40 (ASTM-D1527) or SDR 23.5 (ASTM-D2751) or approved equivalent. A minimum of 6 cubic feet of filter material per linear foot of subdrain shall be placed in the trench. Further, there shall be a minimum of 6 inches of filter material under the pipe. The pipe shall be centered in the trench WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 11 horizontally. Filter material shall comply with CalTrans Class 2 filter material. The last 20 feet of pipe shall be non-perforated with eight feet inside the filter material. Drains should connect to an appropriate storm drain inlet or drainage system. In lieu of Class 2 filter material, 3/4-inch rock wrapped with Mirafi 140N non-woven geotextile, or approved equal, may be used. The geotextile shall lap at least 18 inches on top of the rock. EXPANSIVE SOIL: Detrimentally expansive soils (expansion index of 51 or greater) were encountered in our subsurface exploration (Plate Number 9). These consisted of the near surface clayey sands and sandy clays observed in trenches T-l through T-3 (Plate Numbers 3 through 5). All expansive materials shall be kept at least three feet below the proposed finish subgrade. Expansive soils encountered on cut pads shall be completely removed to a depth of at least three feet below finish subgrade and replaced with granular non-expansive soil. A limited amount of granular non- expansive soil is available both in the terrace deposits and Eocene sandstone on site. IMPORTED FILL: Imported fill, if required at this site, should be examined by our office to determine their suitability prior to importing these materials. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 12 SURFACE DRAINAGE: Surface drainage shall be directed away from structures. The ponding of water or saturation of soils cannot be allowed adjacent to any of the foundations. Surface water must not be allowed to drain in an uncontrolled manner over the top or face of any slope. EARTHWORK: All earthwork and grading contemplated for site preparation must be accomplished in accordance with the attached Specifications for Construction of Controlled Fills. All special site preparation recommendations presented in the sections above will supersede those in the Standard Specifications for Construc- tion of Controlled Fills. All embankments, structural fill, and fill shall be compacted to a minimum of 90%. All utility trench backfill must be compacted to a minimum of 90% of its maximum dry density. The maximum dry density of each soil type shall be determined in accordance with A.S.T.M. Test Method D1557-78. Prior to commencement of the brushing operation, a pregrading meeting shall be held at the site. The Developer, Surveyor, Grading Contractor, and Soil Engineer should attend. Our firm should be given at least 48 hours notice of the meeting time and date. CUT AND FILL SLOPES: We recommend that cut and fill slopes be constructed with a slope ratio of 2.0:1.0 (horizontal .'vertical) or flatter, to a maximum height of 10 feet. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 13 Cut slopes shall be constructed in dense natural soil or rock material. All cut slopes must be inspected for adverse geologic conditions during the grading operation by a representative of our firm. Fill slopes shall be keyed into dense natural ground. The key shall be a minimum of 2 feet deep at the toe of slope and fall with 5% grade toward the interior of the proposed fill areas (Plate Number 11). All keys must be inspected by the Soil Engineer or his representative in the field. Slopes shall be planted as soon as feasible after grading. Slope erosion including sloughing, riling, and slumping of surface soils may be anticipated if the slopes are left unplanted for a long period of time, especially during rainy seasons. Erosion control and drainage devices must be installed in compliance with the requirements of the controlling agencies. RIPPABILITY: The materials encountered within our exploratory trenches are rippable by conventional means to the depths investigated. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 14 FOUNDATIONS GENERAL: Structures should be supported on continuous or pad spread footings bearing in dense natural ground or nonexpansive soil material recompacted in accordance with the recommendations contained in this report. Footings must be designed with the minimum dimensions and allowable dead plus live load bearing values given in the table below: FOOTING PARAMETERS Type Number of of Stories Footing 1 2 1 or 2 Continuous Continuous Pad Minimum Depth (inches) 12 18 24 Minimum Width (inches) 12 15 30 Allowable Soil Bearing Value (p.s.f .) 2000 2500 3500 The minimum depth given shall be below finish subgrade (bottom of sand cushion). All continuous footings shall contain at least one Number 4 reinforcing bar top and bottom to provide structural continuity and to permit spanning of local irregularities. The soil load bearing values presented above may be increased by one-third for short term loads, including wind or seismic. The allowable soil bearing value of import soil material shall be determined after its selection. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 15 Settlement under building loads are expected to be within tolerable limits for the proposed structures. Concrete slabs-on-grade may be supported on compacted on-site soil or dense natural ground. Three inches of clean washed concrete sand shall be placed beneath the slab for curing. Slab reinforcing shall be provided in accordance with the an- ticipated use of and loadings on the slab. In areas where moisture sensitive floor coverings are to be utilized and in other areas where floor dampness would be un- desirable, we recommend consideration be given to providing an impermeable membrane (6-mil visqueen or equal) beneath the slabs. The membrane shall be placed mid-height within the sand to protect it during construction. The sand shall be lightly moistened just prior to placing the concrete. Care shall be taken not to puncture the membrane. All joints (laps) in the membrane should be a minimum of 6 inches in width and sealed with an approved sealer. TRANSITION AREAS: Foundations supported partially on cut and partially on fill are not recommended. The tendency of cut and fill soils to compress differently can frequently result in unequal structural support and subsequent cracking to portions of the structure. Therefore, in transition areas, we recommend that the entire cut area be over excavated and replaced with soils compacted to a minimum of 90%. This over excavation or under- cutting shall be carried to a depth of 2 feet below the bottom of the deepest proposed footing. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 16 LATERAL RESISTANCE: Resistance to lateral loads may be provided by friction at the base of the footing and by passive pressure against the adjacent soil. For concrete footings in compacted or dense natural soil, an allowable coefficient of friction of 0.35 may be used. An allowable passive uniform pressure of 200 pounds per square foot per foot of depth acting against the foundations may be used in design. If footings are proposed adjacent to slope areas, we recommend that the footings be deepened to provide a minimum horizontal distance from the outer edge of footings to the adjacent slope face equal to one-half the height of the slope. This horizontal distance shall be no less than 6 feet and no more than 10 feet. RETAINING WALLS: Retaining walls must be designed to resist lateral earth pressures and any additional lateral loads caused by surcharge loads. We recommend unrestrained walls be designed for an equivalent fluid pressure of 38 pounds per cubic foot (pcf) where backfill is level. We recommend restrained walls be designed for an equivalent fluid pressure of 38 pcf plus an additional uniform lateral pressure of 6H pounds per square foot where H = the height in feet of backfill above the top of the wall footing. Wherever walls will be subjected to surcharge loads, they should be designed for an additional uniform lateral pressure equal to one- third the anticipated surcharge pressure in case of unrestrained WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 17 walls, and one-half the anticipated surcharge in the case of restraining walls. The preceding design pressures assume there is sufficient drainage behind the walls to prevent the build-up of hydrostatic pressures from surface water infiltration. Adequate drainage may be provided by means of weep holes with permeable material installed behind the walls or by means of a system of subdrains. Expansive soils (greater than 5.0 percent swell or an expansive index of 50) shall not be used as retaining wall backfill material. Backfill placed behind the walls shall be compacted to a minimum degree of compaction of 90% using light compaction equipment. If heavy equipment is used, the wall shall be ap- propriately temporarily braced during the compaction process. FOOTING OBSERVATIONS: All footing excavations shall be inspected by the Soil Engineer prior to placing reinforcing steel and concrete. FIELD EXPLORATIONS Five subsurface explorations were made on February 14, 1992 at the locations indicated on Plate Number 1. These explorations consisted of trenches excavated by a Case 455 trackhoe. The trenches were each logged using standard geological techniques. The WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 18 field work was conducted by our geology and soil engineering personnel. The logs are presented on Plate Numbers 3 through 7. The soils are described in accordance with the Unified Soils Classification System as illustrated on the attached simplified chart (Plate Number 2). In addition, a verbal textural description, the wet color, the apparent moisture and the density or consistency are presented. The density of granular material is given as either very loose, loose, medium dense, dense or very dense. The consistency of silts or clays is given as either very soft, soft, medium stiff, stiff, very stiff or hard. Samples of typical and representative soils were obtained and returned to our laboratory for testing. LABORATORY TESTING Laboratory tests were performed in accordance with the American Society for Testing and Materials (A.S.T.M.) test methods or suggested procedures. Test results are shown on Plate Numbers 8 and 9. PLAN REVIEW Western Soil and Foundation Engineering, Inc. should review the grading plans prior to the start of grading. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 19 LIMITATIONS The recommendations presented in this report are contingent upon our review of final plans and specifications. The soil engineer should review and verify the compliance of the final plans with this report and with Chapter 70 of the Uniform Building Code. It is recommended that Western Soil and Foundation Engineering, Inc. be retained to provide continuous soil engineering services during the earthwork operations. This is to observe compliance with the design concepts, specifications or recommendations and to allow design changes in the event that subsurface conditions differ from those anticipated prior to start of construction. Western Soil and Foundation Engineering, Inc. will not be held responsible for earthwork of any kind performed without our observation, inspection and testing. The recommendations and opinions expressed in this report reflect our best estimate of the project requirements based on an evaluation of the subsurface soil conditions encountered at the subsurface exploration locations and the assumption that the soil conditions do not deviate appreciably from those encountered. It should be recognized that the performance of the foundations and/or cut and fill slopes may be influenced by undisclosed or unforeseen variations in the soil conditions that may occur in the inter- mediate and unexplored areas. Any unusual conditions not covered in this report that may be encountered during site development WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates Our Job No. 92-1 February 21, 1992 Page 20 should be brought to the attention of the soil engineer so that he may make modifications, if necessary. This office should be advised of any changes in the project scope so that it may be determined if the recommendations contained herein are appropriate. This should be verified in writing or modified by a written addendum. The findings of this report are valid as of this date. Changes in the condition of a property can, however, occur with the passage of time, whether they be due to natural processes or the work of man on this or adjacent properties. In addition, changes in the State-of-the-Art and/or Government Codes may occur. Due to such changes, the findings of the report may be invalidated wholly or in part by changes beyond our control. Therefore, this report should not be relied upon after a period of one year without a review by us verifying the suitability of the conclusions and recommenda- tions. We will be responsible for our data, interpretations, and recommendations, but shall not be responsible for the interpreta- tions by others of the information developed. Our services consist of professional consultation and observation only, and no warranty of any kind whatsoever, expressed or implied, is made or intended in connection with the work performed or to be performed by us, or by our proposal for consulting or other services, or by our furnishing of oral or written reports or findings. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Laguna Associates February 21, 1992 Our Job No. 92-1 Page 21 It is the responsibility of the Client or the Client's representative to ensure that the information and recommendations contained herein are brought to the attention of the engineer and architect for the project and incorporated into the project's plans and specifications. It is further his responsibility to take the necessary measures to ensure that the contractor and his sub- contractors carry out such recommendations during construction. Respectfully submitted, WESTERN SOIL AND FOUNDATION ENGINEERING, INC. Vince Gaby, Project Geologist Dennis E. Zimmerman VG/DEZ:kw C26676 GE 928 WESTERN SOIL AND FOUNDATION ENGINEERING, INC. ATTACHMENTS WESTERN SOIL AND FOUNDATION ENGINEERING, INC. SITE PLAN PLATE NUMBER 1 (IN BACK POCKET OF THIS REPORT) WESTERN SOIL AND FOUNDATION ENGINEERING, INC. SUBSURFACE EXPLORATION LEGEND UNIFIED SOIL CLASSIFICATION CHART SOIL DESCRIPTION GROUP SYMBOL TYPICAL NAMES I. COARSE GRAINED, More than half of material is larger than No. 200 sieve size. GRAVELS CLEAN GRAVELS More than half of coarse fraction is larger than No. 4 sieve size but smaller than 3" GRAVELS WITH FINES (Appreciable amount of fines) SANDS CLEAN SANDS More than half of coarse fraction is smaller than No. 4 sieve size. SANDS WITH FINES (Appreciable amount of fines) II. FINE GRAINED, More than half of material is smaller than No. 200 sieve size. SILTS AND CLAYS GW GP GM GC sw SP SM SC ML Liquid Limit less than 50 SILTY AND CLAYS Liquid Limit greater than 50 HIGHLY ORGANIC SOILS CL OL MH CH OH PT Well graded gravels, gravel- sand mixtures, little or no fines. Poorly graded gravels, gravel- sand mixtures, little or no fines. Silty gravels, poorly graded gravel-sand-silt mixtures. Clayey gravels, poorly graded gravel-sand, clay mixtures. Well graded sand, gravelly sands, little or no fines. Poorly graded sands, gravelly sands, little or no fines. Silty sands, poorly graded sand and silt mixtures. Clayey sands, poorly graded sand and clay mixtures. Inorganic silts and very fine sands, rock flour, sandy silt or clayey-silt-sand mixtures with slight plast- icity. Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays. Organic silty and organic silty clays of low plasticity Inorganic siltys, micaceous or diatomaceous fine sandy or silty soils, elastic silts. Inorganic clays of high plasticity, fat Organic clays of medium to high plasticity. Peat and other highly organic soils WESTERN SOIL AND FOUNDATION ENGINEERING, INC. PLATE NUMBER 2 H- LU UJ U. *•— ' X1- 0. UJ 1 - 2 - 3 - 5 - 6 - 7 - 8 - 9 - 10 - 11 _ 12 _ 13 _ 14 15 - UJQ. H UJ Q. 2 en B 2 O • O_ — O it CO COCO o :SC '.* • •— S-^;'. •• • * -f '•S'MT'* . • T." •" "* — * *» • 1 • -. '/ . ' • • I•• -*:• *• .'•• • ;T *-&• JOB NUMBER 92-1 TRENCH NUMBER T-l ELEVATION 26± SAMPLING METHOD CASE 455 TRACKHOE DESCRIPTION Dark Gray Clayey Medium to Coarse Sand (Colluvium) grades to Brownish-Gray Silty Medium to Coarse Sand (Very Weathered Santiago Formation Gray Sandy Clay (Santiago Formation) Pale Brown Clayey Medium to Very Coarse Sand (Santiago Formation) BOTTOM OF TRENCH @ 7.5 FEET MARISOL PROJECT LACUNA ASSOCIATES »~ QJ I? f^ K |- 252 Q. O< s Very Moist To Wet Very Moist Very Moist 1- 0z z UJ UJ 01 ^~ Q. V)Q- z< 0o Loose To Medium Dense grades Medium Dense To )ense Stiff Dense DATE LOGGED 2-14-92 l- to _z u_ LU (J 0 Q. tro ai 5?ir -* D >- iii 0 Z 5 0 O ^0 UJ K — UJ g fK ^ O — — — — — — — - — — - - — LOGGED BY V.G. SUBSURFACE EXPLORATION LOG PLATE NO. 3 \- LU LUu. *~* X tr- LU P 1 - 3 - 4 - c 6 - 7 - - 8 — 9 - — 10 - 1 i 12 _ 13 _ 14 15 - LUQ. £ LU Q. <in C ( . (__ — O t (/) If V< u.'••'. .- £3 rf^l:/.sc ':;'.-^/ '.-.'.— ;" •fSM *.-'•' *j_ rr! • • :'r',— - rrf '-"'-" - "- :"•••"• 4- SI* • ' " ' ' '*• * \T-/:v '..•*."•' . 77- y" * * •' • * . • SP.\ T o "**• •.' SCi ' • '.TT '.•••'.• -rfe? JOB NUMBER 92-1 TRENCH NUMBER f-2 ELEVATION 26± SAMPLING METHOD CASE 455 TRACKHOE DESCRIPTION Very Dark Brownish-Gray Very Sandy Clay to Clayey Medium to Coarse Sand (Colluvium Brown Very Well Cemented Silty Fine to Medium Sand grades to Brownish-Orange Moderately Well Cemented Slightly Silty Fine to Medium Sand (Terrace Deposits) Dark Gray Slightly Silty Medium To Coarse Sand grades to Gray Clayey Medium to Coarse Sand (Santiago Formation) BOTTOM OF TRENCH @ 11.0 FEET BEST ORIGINAL MARISOL PROJECT LACUNA ASSOCIATES »- UJ Z £ LO ^^ OL. }— ^X CO Ov ™~Q. 0 < 5 Wet Damp Moist To Very Moist 1- 0z z LU LUtc J-< 52fl tn**• VJQ- Z< 0 U Soft To Loose Dense Dense DATE LOGGED 2-14-92 t- Crt ^z u. U oQ 0. . *^ tra 121 .•; UJ 5s cc — D >~ h~in £ 0 Z 2 0 O 5.8 v£ UJ> 2 i —^ f~. o UJ Q.o: zoo — — — — — _ — — — — — — — — - — LOGGED BY V.G. SUBSURFACE EXPLORATION LOG PLATE NO. 4 J- UJ UJu. X n UJ P 1 _ 2 - — . 3 - 4 ~ 5 - 6 - — 7 - 8 - — — 10 - 11 _ 12 _ 13 _ 15 - UJ#%Q. £[ UJ_J Q. 2 in •MMMM B C C 2C < 0 t V **_lU Tr--.^-:.';. V"\v-:-— 7—*^- '.'•'.'— ;,-•'. P •S C if "i§S?'s^l r. CM.'. • O 1 1 • T- • -•'-' fs'.w; :'•'.'!: '.-:. ;.•.•".•'.;-:'• •i^!/-- ."•*"•-'•" •/-•. ?" .'••'"-" V ~T*.* ;,; f ~'» SPL* .*-•* ~. *"* JOB NUMBER 92-1 » > TRENCH NUMBER T~3 ' ELEVATION 18± N >• SAMPLING METHOD CASE 455 TRACKHOE DESCRIPTION Brown Silty Fine Sand Interlayerec with White Very Silty Sand (Fill) Very Dark Gray Sandy Clay to Black Clayey Sand with Glass Fragments (Fill) . ' — • ~ Dark Brown Poorly Cemented Silty Fine to Medium Sand, with Thin Shelly Layer ,grades to Orangish-Br own Slightly Silty Fine to Medium Sand, Moderately Well Cemented grades to Brownish-Orange Fine to Medium Sand (Terrace Deposits) Pale Orangish-Gray Slightly Silty Medium to Coarse Sand (Santiago Formation) BOTTOM OF TRENCH @ 10.5' BEST ORIGINAL MARISOL PROJECT LACUNA ASSOCIATES •* 111 2 £EUJ 3 2 12o_ o< S 1 Very Moist Very Moist To Wet — — ^^— • Moist Damp Damp Moist >_ K 0z z UJ UJ £ -Q" {/5Q- Z< 0o Loose Soft To Loose Loose To Medium Dense Dense Very Dense Dense To Very Dense DATE LOGGED 2-14-92 V) -^Z u. UJ o 0 Q. . "" Ka .^— -^— ^— ••• 105.6 122.4 123.5 . 1 V?LU o- CE ~ , z cn £ 5 z 2 0 O •i^— ^— — 6.4 5.3 4.2 * UJ> ^ 1- — ^J ftCC 3P o "~" — ~ — — — — — — — - ™" —: — - LOGGED BY V.G. SUBSURFACE EXPLORATION LOG PLATE NO. 5 h- UJ UJu. X f\L^ UJP 1 -_ 2 - 3 - 4 - 5 - — 6 - — 7 — 8 - — 9 - 10 - 11 12 _ 13 _ 14 15 - UJOL l_ UJ Q_ 3.<CO B _ O 1- (_ 0 tfrt Cjwj v < u ?rr£i ''.'4.'.- :-SC "*-•••.—-'•".T-- .•••-.'/.i '* . "_J,;••*.•:?SPvj-l i'J*-'" • *]'-! •/."•••.* V» • ' * '*."•"* t • *.>.*•>'£ ?s'p:, • ••"••" ••.•'•'•T- • * • * •" • * "*.*."• *. • ,'t . "•"*"*"• |~ * ", • • ,-y-f ' J.•".'*"*!*# || -^ : :-?:'-;•.'.• JOB NUMBER 92-1 TRENCH NUMBER T-4 ELEVATION 9± SAMPLING METHOD CASE 455 TRACKHOE DESCRIPTION Brown Clayey Silty Medium to Coarse Sand, with Minor Fragments of glass and asphalt (Fill)\ •"• -1- -1- -1- / (Surface Water infiltration seeping at 2.0 Feet) White to Very Pale Gray Slightly Silty Medium to Very Coarse Sand grades to White Silty Medium to Coarse Sand (Groundwater seepage at 7.75 Feet (Santiago Formation) Dark Yellowish Gray Very Silty Very Fine to Fine Sand (Santiago Formation) BOTTOM OF TRENCH @ 11.0' FEET BEST ORIGINAL MARISOL PROJECT LACUNA ASSOCIATES H Z (r UJ o 2<2o_ o < "£. Wet Very Moist 3-1 Very ^oist H- O Z Z UJ UJ5£ Q. z< oo Loose Dense Dense Dense DATE LOGGED 2-14-92 t- V) _ Z ulUJ (j Q Q. j_ ""* £E0 125.7 UJ 5s °" ^^ _ 2 H 0 Z 5 O O 11.1 vO UJ — OJ_ —50 UJ Q. o - — 101.6 — — — ~~ •~— — — —_ — — — - . . — — - — LOGGED BY V.G. SUBSURFACE EXPLORATION LOG PLATE NO. 6 UJ UJu. ~—I Q. UJ P 1 - - — 3 — 4 ~ 5 - 6 - __ 7 - 8 - 9 - - 10 11 _ _ 12 _ 13 _ 14 15 - UJQ. i_i^ UJ Q. 2 in _ O . (.— ' -_ 0 i CO CO V o *,' • t'. '• ' ' "".'•' • •' •• ";.SC '.'if^fr f/s'p • "_i_»>",V fF;7£^sp; %£s •7-rJ-; I'ML 7l>.l- ^-•^1^" T-7^. IrL^Ii ~-r-r7 -'T-^V "L~J: JOB NUMBER 92-1 TRENCH NUMBER T-5 ELEVATION 6± SAMPLING METHOD CASE 455 TRACKHOE DESCRIPTION Brown Silty Clayey Fine to Medium Sand with Minor Refuse (Fill) Medium bedded Silty Fine to Medium grained and Coarse Grained O J •j_l_-C"l.i_"l* Jband with flat lying wood fragmpnt « (Beach Deposits) Brownish-Orange thin bedded fine to Coarse Sand (Beach Deposits) Very Dark Gray Sandy Silt^Slight Organic Odor TRENCH WALLS CAVING groundwater seepage @ 6.75 Feet (Recent Beach/Lagoon Deposits) .BOTTOM OF TRENCH @ 10.0 FEET Trench Terminated Due to Profuse Caving BEST ORIGINAL MARISOL PROJECT LACUNA ASSOCIATES *- uiz crUJ 3 OL, ^ < CO Q. 0 < 2 Wet Wet Wet Wet .V. H 0z z UJ UJa: >-< _ CL Z< Oo Loose Loose Loose Soft DATE LOGGED 2-14-92 K co _ Z u. LU (jQ a. DC 0 UJ o5 CC "~" ^ _ h~ CO UJ O Z 2 0o vO UJ — O}- — ^ U UJ CLfy 2 O — — — ~™ ™~"~ — — — — — — — — — — - - : LOGGED BY V.G. SUBSURFACE EXPLORATION LOG PLATE NO. 7 LABORATORY TEST RESULTS Sample Location MAXIMUM DENSITY/OPTIMUM MOISTURE Description Maximum Dry Optimum Density Moisture (pcf) (Percent) T-4 <§ 2.5'White Slightly Silty Medium to Very Coarse Sand 123.7 11.4 DIRECT SHEAR* Sample Location Apparent Cohesion (psf) Angle of Internal Friction (degrees) Sampled from Terrace Deposits in Site Vicinity *T-4 2.5' 50 200 33 34 * Sample remolded to 90% of maximum dry density at 3% over optimum moisture content. All samples saturated prior to testing. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. PLATE NO. 8 MECHANICAL SIEVE ANALYSIS Sample Location Percent Passing U.S. Standard Sieve #4 #10 #40 #100 #200 T-4 @ 2.5' 98.1 88.2 39.7 22.1 15.8 EXPANSION INDEX* Sample Location Expansion Index Initial Moisture Content (Percent) Final Moisture Content (Percent) Expansion Potential T-l @ 1.0 59 9.9 21.4 Medium * Sample tested per UBC Standard No. 29-2 WESTERN SOIL AND FOUNDATION ENGINEERING, INC. PLATE NO. 9 TABLE I TRENCH NUMBER DEPTH OF SOIL REMOVAL BELOW EXISTING GRADE (FEET) T-l T-2 T-3 T-4 T-5 4.0 2.5 5.0 2.0 10.0 + NOTE: It should be recognized that variations in soil conditions may occur between exploratory trenches that will require additional removal. In areas where fill slope toe keys are proposed, add a minimum of 2.0 feet to removal depths presented above. The soil in the exploratory trenches encountered in the removal process should be removed and recompacted to 90 percent relative compaction. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. PLATE NO. 10 FILL SLOPE KEY NATURAL GROUND PROJECTED PLANE I TO I MAXIMUM FROM TOE OF SLOPE TO APPROVED GROUND FILL 8' MINIMUM BENCH MINIMUM DOWNSLOPE KEY DEPTH COMPETENT EARTH MATERIAL TYPICAL BENCH (HEIGHT VARIES} BACKDRAINS MAY BE REQUIRED PER RECOMMENDATIONS OF SOILS ENGINEER MARISOL PROJECT CARLSBAD, CALIFORNIA JOB NO. 92-1 DATE 2-21-92 SOIl. AND FOUNDATION ENGINEERING INC. PLATE NO. 11 APPENDIX I WESTERN SOIL AND FOUNDATION ENGINEERING, INC. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. PHONE 746-3553 AREA CODE 619 423 HALE AVENUE ESCONDIDO. CALIFORNIA 92029 SPECIFICATIONS FOR CONSTRUCTIOK OF CONTROLLED FILLS GENERAL DESCRIPTION: The construction of controlled fills shall consist of adequate preliminary soil investigations, and clearing, removal of existing structures and foundations, preparation of land to be filled, excavation of earth and rock from cut area, compaction and control of the fill, and all other work necessary to complete the grading of the filled area to conform with the lines, grades, and slopes as shown on the accepted plans. CLEARING AND PREPARATION OF AREAS TO BE FILLED; (a) All fill control projects shall have a preliminary soil investigation or a visual examination, depending upon the nature of the job, by a qualified soil engineer prior to grading. (b) All timber, trees, brush, vegetation, and other rubbish shall be removed, piled and burned, or otherwise disposed of to leave the prepared area with a finished appearance free from unsightly debris. (c) Any soft, swampy or otherwise unsuitable areas, shall be corrected by drainage of removal of compressible material, or both, to the depths indicated on the plans or as directed by the soil engineer. (d) The natural ground which is determined to be satisfactory for the support of the filled ground shall then be plowed or scarified to a depth of at least six inches (6") or deeper as specified by the soil engineer, and until the surface is free from ruts, hummocks, or other uneven features which would tend to prevent uniform compaction by the equipment to be used. (e) No fill shall be placed until the prepared native ground has been approved by the soil engineer. (f) Where fills are made on the hillsides with slopes greater than 5 (horizontal) to 1 (vertical), horizontal benches shall be cut into firm undisturbed natural ground to provide lateral and vertical stability. The initial bench at the toe of the fill shall be at least 10 feet in width on firm undisturbed natural ground at the elevation of the toe stake. The soil engineer shall determine the width and frequency of all succeeding benches which will vary 'with the soil conditions and the steepness of slope. page 2 (g) After the natural ground has been prepared, it shall be brought to the proper moisture content and compacted to not less than 90% of maximum density, A.S.T.M. D1557-78. (h) Expansive soils may require special compaction specifications as directed in the preliminary soil investigation by the soil engineer. (i) The cut portions of building pads in which rock-like material exists may require excavation and recompaction for density compatibility with the fill as directed by the soil engineer. MATERIALS: The fill soils shall consist of select materials graded so that at least 40 percent of the material passes the No. 4 sieve. The material may be obtained from the excavation, a borrow pit, or by mixing soils from one or more sources. The material used shall be free from vegetable matter, and other deleterious substances, and shall not contain rocks or lumps greater than 6 inches in diameter. If excessive vegetation, rocks, or soils with unacceptable physical characteristics are encountered, these materials shall be disposed of in waste areas designated on the plans or as directed by the soil engineer. If soils are encountered during the grading operation which were not reported in the preliminary soil investigation, further testing will be required to ascertain their engineering properties. Any special treatment recommended in the preliminary or subsequent soil reports not covered herein shall become an addendum to these specifications. No material of a perishable, spongy, or otherwise unstable nature shall be used in the fills. PLACING, SPREADING AND COMPACTING FILL MATERIAL: (a) The selected fill material shall be placed in layers which shall not exceed six inches (6") when compacted. Each layer shall be spread evenly and shall be thoroughly blade-mixed during the spreading to insure uniformity of material and moisture in each layer. (b) When the moisture content of the fill material is below that specified by the soil engineer, water shall be added until the moisture content is near optimum as determined by the soil engineer to assure thorough bonding during the compacting process. (c) When the moisture content of the fill material is above that specified by the soil engineer, the fill material shall be aerated by blading and scarifying, or other satisfactory methods until the moisture content is near optimum as determined by the soils engineer. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. page 3 (d) After each layer has been placed, mixed and spread evenly, it shall be thoroughly compacted to not less than the specified maximum density in accordance with A.S.T.M. D1557-78. Compaction shall be by means of tamping or sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other types of rollers. Rollers shall be of such design that they will be able to compact the fill to the specified density. Rolling of each layer shall be continuous over its entire area and the roller shall make sufficient passes to obtain the desired density. The entire area to be filled shall be compacted to the specified density. (e) Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compacting operations shall be continued until the slopes are stable but not too dense for planting and until there is no appreciable amount of loose soil on the slopes. Compacting of the slopes shall be accomplished by backrolling the slopes in increments of 3 to 5 feet in elevation gain or by other methods producing satisfactory results. (f) Field density tests shall be made by the soil engineer for approximately each foot in elevation gain after compaction, but not to exceed two feet in vertical height between tests. The location of the tests in plan shall be spaced to give the best possible coverage and shall be taken no farther than 100 feet apart. Tests shall be taken on corner and terrace lots for each two feet in elevation again. The soil engineer may take additional tests as considered necessary to check on the uniformity of compaction. Where sheepsfoot rollers are used, the tests shall be taken in the compacted material below the disturbed surface. No additional layers of fill shall be spread until the field density tests indicate that the specified density has been obtained. (g) The fill operation shall be continued in six inch (6") compacted layers, as specified above, until the fill has been brought to the finished slopes and grades as shown on the accepted plans. SUPERVISION; Supervision by the soil engineer shall be made during the filling and compacting operations so that he can certify that the fill was made in accordance with accepted specifications. The specifications and soil testing of subgrade, subbase, and base materials for roads, or other public property shall be done in accordance with specifications of the governing agency. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. page 4 SEASONAL LIMITS: No fill material shall be placed, spread, or rolled during unfavorable weather conditions. When the work is interrupted by heavy rain, grading shall not be resumed until field tests by the soil engineer indicate that the moisture content and density of the -fill are as previously specified. In the event that, in the opinion of the engineer, soils unsatisfactory as foundation material are encountered, they shall not be incorporated in the grading, and disposition will be made at the engineer's discretion. WESTERN SOIL AND FOUNDATION ENGINEERING, INC. APPENDIX II WESTERN SOIL AND FOUNDATION ENGINEERING, INC. REFERENCES CITED m Kennedy, Michael P., 1975 Geology of The San Diego Metropolitan Area, California: California Division of Mines and Geology, m Bulletin 200. m Singh, Awtar, 1970, Shear Strength and Stability of Man-Made Slopes: Journal of the Soil Mechanics and Foundation Division, ASCE m SM6, (November 1970,) pp. 1879-1892. m m Weber, F. Harold Jr., July 1, 1982, Recent Slope Failures, Ancient Landslides, and Related Geology of the North-Central Coast Area, ** San Diego County, California, CDMG Open-File Report 82-12. «M m Wilson, Kenneth L., December 1972, "Eocene and Related Geology of a Portion of the San Luis Rey and Encinitas Quadrangles San Diego KM County, California", Masters Thesis, U.C. Riverside. WESTERN SOIL AND FOUNDATION ENGINEERING, INC.