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HomeMy WebLinkAboutCT 73-24; Seacliffs; Soils Report; 1975-08-26"'FIVED AUG 2 'i 1975 ~ LAHLSBAD Enginwnng Department f \ SOIL ENGINEERING AND FOUNDATION INVESTIGATION + 5.5 Acre Commercial Site Southeazerly of Poinsettia Lane and the San Diego Freeway (Interstate 5) in the City of Carlsbad, California (Tract 72-24, Lot 171) J for Occidental Land, Inc. August 26, 1975 RECEIVED AUG2 7 1975 CITY OF CARLSBAD Englneerlng Department bY Pacific Soils Engineering, Inc. Irvine, California PACIFIC SOILS ENGINEERING, INC. TELEPHONE: (714) 557-9450 17921 SKY PARK CIRCLE (SUITE G) IRVINE. CALIF. 92707 Occidental Land, Inc. P.O. Box 305 El Toro, CA. 92630 Attention: Mr. Nori Kataoka Subject: Soil Engineering and Foundation Investigation; - + 5.5 Acre Commercial Site, Southeasterly of Poinsetfia Lane and the San Diego Freeway (Interstate 5), in the City of Carlsbod, CA. (Tract 73-24, Lot 171). Reference: Sail Engineering and Foundation Investigation Report for Tract 73-23; 31.48 Acre Multi-Family Residential Subdivision, Northeasterly of Poin- settia Lane and Lowder Lane, in the City of Carlsbad, California, by Pacific Soils Engineering, Inc., dated December 16, 1974 (W.O. 100361). LA. COUNTY OFFICE Harbor City. Ca. 90710 1402 W. 240th Street (213) 325-7272 or 775-6771 VENTURA COUNTY OFFICE Post Oiilc(1 Box 75 (213) 889-9919 (805) 495-6513 Thousand oam. ca. 91360 August 26, 1975 Work Order 100407 Gentlemen: This report presents the results of a soil engineering and foundation investigation performed on the subject site. An 8&scale, topographic map, supplied by the client, ws used for reference during our Field exploration and preparation of this report. A print of a 4Gscale grading plan, prepared by William G. Church, Consulting Civil Engineers, is enclosed with this report. The site is to be developed as a neighborhood shopping center complex. Proposed site grading will consist of imported fill to attain the desired grades. Types of structures and actual founda- tion loads are not available as of this writing. August 26, 1975 Work Order 100407 Page 2 According to the plan, compacted fill slopes are programmed at ratios of two horizontal to one vertical, to a maximum vertical height of 25-feet +. The maximum vertical depth of fill is on the order of 23 to 25-feet. Cuts are not programmed for the proposed development. - SITE LOCATION AND DESCRIPTION The site is an irregular shaped 5.5 + acre parcel located southeasterly of Poinsettia Lane and Interstate 5, the Son Diego Freeway, in the City of Carlsbad. The property has apparently been used in the past for farming purposes. However, at the time of our exploration, a dense cover of tall weeds was present. Existing fill was neither observed, nor encountered. Although none vms observed, irrigation lines may be present on the site. - The site terrain consists of a relatively uniform slope, which descends westerly from the easterly boundary to the freeway, at a gradient of about eight percent. Maximum relief on the site is approximately -feet. DISCUSSION The site is considered suitable for the vpe of development proposed from a soil engineering standpoint. Existing soils are granular ond non-expansive in nature. 77,W to 87,000 cubic yards of material is to be imported to the site from Tract 73-23, northeasterly of the subject site. These materials are also granular and non-expansive. The soil profile, as revealed in the test pits, consists of reddish-brown, brown and yellowish- sands to the depths explored. The aforementioned-materials consist of marine terrace deposits. PACIFIC SOILS ENGINEERING, INC. August 26, 1975 Work Order 100407 Page 3 The upper one to two feet of terrace materials were found to be dry and loose. Below two- feet to the depths explored, the soils are slightly moist to moist and moderately to well con- solidated. Removal and/or processing of the upper soils will be required to provide a suitable base for compacted fill or foundations. Bedrock exists beneath the terrace materiols, based upon the past explorations by our firm northerly of Poinsettia Lane. Bedrock wcls not encountered in the exploratory pits for the subject investigation. The depth of loose, poorly consolidated surface soil varies from one to two feet in depth. Soils below these depths are medium dense. Upper soils will have to be processed, cleaned of organic material, and thoroughly compacted beneath the proposed compacted fill. Compacted fill slopes will be considered grossly stable as planned. Silty and clayey sands will be the dominant material exposed on finished compacted fill slopes. These materials will be subject to surface to surface erosion during periods of heavy rainfall. It is recommended that compacted fill slopes, five-feet and greater in vertical height, be seeded or planted as soon as practical after completion of grading in order that vegetal growth is established at the earliest possible time. Stability calculations have been made using shear strength parameters determined for the pro- posed imported fill material. These calculations were presented in the referenced report. The ultimate bearing capacity wos determined utilizing remolded shear strength choracteristics. The calculations, likewise presented in the referenced report and attached Plate C, indicate that the soils placed as compacted fill, will have adequate bearing capacity to support anticipated structural loads. PACIFIC SOILS ENOINEERINQ. INC. August 26, 1975 Work Order 100407 Page 4 Ground-water wcls not encountered in the exploratory excavations, nor is any anticipated during the proposed grading operations. PACIFIC SOILS ENQINEERINQ. INC. August 26, 1975 Work Order 100407 Page 5 CONCLUSIONS AND RECOMMENDATIONS Based upon the field exploration, laboratory testing and analyses, and our visual observations of field conditions, the following conclusions and recommendations are submitted. Site Preparation and Grading 1. 2. 3. 4. 5. Vegetal cover should be cleared from the site surface and removed from the property. Some hand picking of roots may also be required during the initial stages of processing and precompaction operations. All irrigation pipe(s) (if encountered) should be removed. Prior to placing compacted fill, the upper 12-inches of native materials should be removed, and the underlying 12-inches processed and compacted in-place to a minimum of 90 percent of the laboratory standard. It may prove to be beneficial to pre-water, prior to grading, due to the extremely dry site conditions. Existing fill materials (if encountered) should be removed and recompacted during the course of the site grading. A level toe bench excavation, minimum 15-feet in width, should be made to establish proposed compqcted fill slopes on the natural slopes. This toe bench excavation should be a minimum of one-foot deep at the toe. Since the depth of loose, poorly consolidated surface soils on the site is anticipated to vary, final determinations regarding depths of removal will have to be made in the field during grading. PACIFIC SOILS ENQINEERINQ. INC. August 26, 1975 Work Order 100407 Page 6 6. Fill should be spread in thin lifts, wutered or air-dried as necessary to attain a near optimum moisture content and compacted to a minimum of 90 percent of the laboratory standard. 7, Fill slopes should be back-rolled with a sheepsfoot roller at intervals of four-feet, or less in height as filling progresses. The finished fill slope surfaces should then be com- pacted either by track-rolling or utilizing a sheepsfoot and grid roller operated from a boom tractor. The moisture content of soils at the finished slope surfaces should be at or near optimum moisture at the time slope compaction is accomplished. Fill slopes may be over-filled and trimmed back to a compoct surface in lieu of grid-rolling. Design 1. A bearing capacity of 2,000 Ibs./sq.ft. may be used for foundation design. Interior and exterior footing embedments for single-story construction should be a minimum of 12-inches below the lowest adjacent grade. Exterior footing embedments for two-story construction should be increased to 18-inches. All footings should be a minimum of 12-inches wide. Bearing capacity calculations, based on direct shear strength parameters, are presented on Plate C. An allowable lateral bearing of 300 Ibs./sq.ft. per foot of depth of a maximum of 1500 Ibs./sq.ft. and a lateral sliding coefficient of 0.4 may be utilized in foundation design. The above values may be increased by one-third to resist wind or seismic loads. Continuous and isolated pier footings may be utilized. PACIFIC SOILS ENGINEERING, INC. August 26, 1975 Work Order 100407 Page 7 2. 3. 4. 5. Subsequent to grading operations and prior to actual building construction, foundation and development plans should be reviewed and approved by the foundation engineer prior to submittal to the governing agency. Pacific Soils Engineering, Inc. is available for consultation during the preparation of the plans. Native onsite soils, which are anticipated to be involved in grading, are non-expansive in nature. Foundation reinforcement should be based upon a review of proposed structure types and actual as-graded conditions. Floor slabs-on-grade should be o minimum of four-inches (nominal) in thickness. A rock base capillary break beneath floor slabs is not regarded as necessary. A moisture barrier membrane such as a &mil "Visqueen", or equivalent, placed on compacted subgrade should be provided beneath floor slabs requiring low surface moisture. The barrier mem- brane should be covered with a minimum thickness of one-inch of clean sand to protect it and provide for proper curing of the concrete. Surface drainage should be directed away from foundations. Roof and area runoff should be directed away from the buildings. Footing excavations should be trimmed neat and should be free from slough or loose material, prior to placing concrete. Anticipated differential settlement under estimated structural loads should be less than one-quarter inch for foundations designed and constructed as recommended, ad in con- sideration of the recommended site grading recommendations. PACIFIC SOILS ENGINEERING, INC. August 26, 1975 Work Order 100407 Page 8 6. Compacted fill slopes will be considered grossly stable at the gradients and the heights programmed, provided that they are constructed in accordance with the recommendations set forth in this report. SEISMICITY The site is located about equidistant from the three major fault systems (Newport-lnglewod, Agua-Caliente and Wittier-Elsinore). Numerous earthquakes along these fault systems have taken place in the past and will take place in the future, influencing the site and its proposed development. Existing earth-science data and state-of-the-art methods are such that the anticipated types of structures proposed for the site can be adquately designed and constructed taking into account seismic factors. Proposed commercial structures should be designed in accordance with current seismic design criteria of the City of Carlsbad, which is contained in the 1973 edition of the Uniform Building Code. The site is located approximately 44 miles southeast of the Newport-Jnglewood fault zone, 26 miles southeast of the Whittier-Elsinor fault zone, and 34 miles southwest from the Agua- Caliente fault zone (See Figure 1). The Long Beach Earthquake of 1933, the epicenter of which occurred in the Pacific Ocean off of Newport Beach approximately 50 miles northwesterly of the site, registered 6.3 Richter Magnitude. PACIFIC SOILS ENQINEERINQ. INC. August 26, 1975 Work Order 100407 Page 9 A Richter Magnitude of 5.5 to 5.9 epicenter is the next highest recorded earthquake nearby. That epicenter is about 43 miles northwesterly of the property near Santiago Peak and is associated with the Whittier-Elsinore fault zone. Fault Displacement No faults were indicated on the property in our search of available publications, nor was there any evidence to indicate the presence of faulting during our field investigation. In addition, no faults that are considered active are located in the near proximity of the property; therefore, surface ground rupture appears remote. Ground Shaking The site will experience ground shaking during the life of the project. The effect of ground shaking will be influenced by not only the nature of the sails and underlying bedrock, but also by the magnitude of the seismic event and the distance from the causative fault. Pre- dominant period of motions and duration of shaking are also factors; however, for the iype of structures planned, it is not considered necessary to include these parameters in the ground shaking evaluation presented below: LIMITED SEISMIC ANALYSIS DATA SHEET Mtles from Epicenter to nitude Accl. (modify Epicenter Locality of Epicenter Mag- Max. Intensity No. Relative to Site Fault Name Site (Richter) (%) mercali sca 1 offshore Newport Beach Newport- 50 6.3 0.07 IX (Long Beach Earthquake lnglewood 1933) 2 near Santiago Peak Whittier- 43 E!sinore (1 938) PACIFIC SOILS ENGINEERINO, INC. 5.5 0.045 ? August 26, 1975 Work Order 100407 Page 10 3 Sylmar (1971) San Fernando 105 6.6 0.00 ? 4 Bryn Maw (1923) San Jacinto 62 6.3 0.03 ? 5 Hemet (1918) San Jacinto 48 6.8 0.075 IX 6 Tehachapi (1 952) White Wolf 152 7.7 0.00 XI 7 Fish Creek Mountains Agua-Caliente 82 6.5 0.04 ? (1 942) Liquefaction No wafer was encountered over the project area to the depths explored. Based upon the sub- surface investigation, the soils encountered were dense and not conducive to liquefaction. Pacific Soils Engineering, Inc. warrants that its findings and recommendations contained in this report are predicated upon the specific test pits and laboratory data as noted and upon the referenced report. The strata immediately adjacent or beneoth may have different characteristics. This warranty is expressly in lieu of all other warranties expressed or implied; and no person, firm or corporation is authorized to make any other warranty in lieu thereof on behalf of Pacific Soils Engineering, Inc. This report is subject to review by the controlling authorities for the subject project. Respectfully submitted, PACIFIC SOILS ENGINEERING, INC. Disk (4) Addressee (2) City of Carlsbad, Eng. Dept. (1) Church Engineering Attn: Bill Allen By: Attn: Jan Adams RICHARD E. LCWNES, E.G. 108 Reviewed by: BY: General Manager AJJ:REL:RPK/scb PACIFIC SOILS ENCilNEERINP, INC. ENGINEERING FEATURES AND FAULT MAP Reference: Proctor, R. J., 1966. Index Map of Selected Maior Geologic and Engineering Features of Southern California in Engineering Geology in Southern California; Special publication of Association of Engineering Geology, Southern California Section, 1966, reprinted edition, 1969. August 26, 1975 Work Order 100407 REFERENCES Housner, G. W., 1965, Strong Ground Mdtion; in Earthquake Engineering, Prentice-Hall, pp. 7592. - Proctor, R. J., 1966, Index Map of Selected Maior Geologic and Engineering Features of Southern California in Engineering Geology in Southern California; Special publication of Association of Engineering Geology, Southern California Section, 1966, reprinted edition, 1969. PACIFIC SOILS ENPINEEPING. INE August 26, 1975 Work Order 100407 APPENDIX A. Field Investigation Seven exploratory test pits were made to depths ranging between five and 12-feet with a rubber-tired backhoe, at the locations indicated on the enclosed plan. Bulk and undisturbed samples were obtained from the exploratory excavations for testing in our laboratory. The material encountered was continuously lagged by our field engineer and classified by visual examination in accordance with the Unified Soil Classification System, as shown on Plate A. Logs of the Test Pits are presented in Table 1. B. Laboratory Tests Laboratory maximum density determinations were made on representative samples of the upper soils to determine compaction characteristics, and for use during earth grading operations. Particle size determinations were performed on representative samples to aid in class- ification of the soils. Shear tests were performed on undisturbed samples with direct shear machine of the strain control type in which the rate of strain is 0.05-inches per minute. The machine is so designed that tests may be performed without removing the specimens from the rings in which they were obtained, insuring a minimum of disturbance from the initial condition, Specimens were subjected to shear under various normal loads and moisture conditions. Moisture-density tests were performed on undisturbed samples obtained during our field exploration. Swell tests were made on a remolded sample, considered to be the most critical of the various soils encountered. The above laboratory tests are presented in Table 11. Consolidation tests were performed on specimens of the representative soils. The con- solidometen, like the direct shear machine, are designed to receive the specimens in the rings in the field condition. Porous stones, placed at the top and bottom of each specimen, permit the free flow of water from the specimen during the test. Water was introduced at a loading of one ton per square foot. Progressive and final settlements results are presented on Plates 8- 1 and B-2. under increasing load increments were recorded to an accuracy of 0.0001-inch. Test PACIFIC SOILS ENOINEERINO. INC. Unified Soil Classification (Including Identification and Description) I I 2 1 I CONSISTENCY Gronular Soil " Very Loose Loose Moderately Cense Medium De= Dense Very Dense CLASSIFICATION Cohesive Bedrock Soil very sofi Soft Firm SOtt Stiff Mcdemtety lion Very Stiff Hard Hord Very Hard Moisture Variation Dry . Slightly Moist Moist Wet Satumted .. R - Undisturbed Sample B -Bulk Sample P - Groundvrater Table Q- Groundwater Seepage I PACIFIC SOILS ENGINEERING, INC. W.O. 100407 DATE 8/26/75 Plate August 26, 1975 Work Order 100407 TABLE 1 LOG OF TEST PITS Pits Excavated on August 18, 1975 Test Pit Depth (ft.) USCS - Description 1 0.0 - 8.0 SP TERRACE DEPOSITS: Fine sand, red-brown, very dry, dense; slightly moist at 2.0 ft.; moist at 2.5 ft. END OF EXCAVATION No Water - No Caving ......................................... 2 0.0 - 4.0 SP TERRACE DEPOSITS: Fine sad, red-brown, loose dry; moist and medium dense at 0.5 ft., with vertical white sand striations. 4.0 - 12.0 sw Sand, red-brown, moist, medium dense, contains white-yellow sand striations. END OF EXCAVATION No Water - No Caving ......................................... 3 0.0 - 4.0 SP TERRACE DEPOSITS: Fine sand, brown, dry, very dense; slightly moist at 2.0 ft. 4.0 - 10.0 sw Red-brown, sand, moist, dense. END OF EXCAVATION No Water - No Caving 4 0.0 - 10.0 SP TERRACE DEPOSITS: Sand, red-brown, loose, dry, dense below 1.0 ft.; moist, medium dense below 3.0 ft. END OF EXCAVATION No Water - No Caving """""""""""""""""""""""""""""""""""""""""- 5 0.0 - 0.5 SP TERRACE DEPOSITS: Fine sand, brown, dry, loose. 0.5 - 12.0 sw Sand, red-brown, moist medium dense; below 5.5 ft. moist to very moist, medium dense. END OF EXCAVATION No Water - No Caving .......................................... PACIFIC SOILS ENGINEERINO, INC. 'August 26, 1975 Work Order 100407 Test Pit ' Depth (ft .) - USCS 6 0.0 - 2.5 sp/ sw 2.5 - 6.0 sw 6.0 - 10.0 sw Description TERRACE DEPOSITS: Sand, brown, very dry, loose; below 1 .O ft. slightly moist, medium dense. Sand, red-brown, moist, dense. Sand, yellow-brown, moist, dense. END OF EXCAVATION No Water - No Excavation ........................................... 7 0.0 - 5.0 SW TERRACE DEPOSITS: Sand, red-brown, dry, loose; slightly moist, very dense below 1.0 ft.; moist, dense, below 3.0 ft. END OF EXCAVATION No Water - No Excavation """"""""""""""~""""""""""""""""""""""""""""- PACIFIC SOILS ENQINEERINO. INC. August 26, 1975 - Work Order 100407 TABLE I1 LABORATORY TEST RESULTZ Compaction Data: Laboratory Standard: ASTM: D 1557-7OT Hydrometer Analysis Location Opt. Moist. Max. Dry Density Soil Type (% Sand, Silt, Clay) & Depth ("/.I (Ibs./cu.ft.) A - Sand 81 4 15 Pit 2 @ 2' 9.5 B - Sand 86 6 8 Pit 7 @0.5' 9.5 In-Place Densitv 127.0 120.0 Moisture Unit Dry Weight Pit No. Depth (ft.) ("/.I (Ibs./cu.ft.) - 1 2 4 5 5 5 6 7 lOl* 102" - 103* - 2.5 4.0 5.5 2.0 5.5 9.0 4.0 5.0 1.5 1.5 0.5 5.3 6.1 7.2 2.3 7.0 11.7 7.0 . 5.3 2.8 1.5 1 .o 105.0 106.6 102.1 102.8 102.0 108.7 112.0 99.5 106.7 109.8 106.4 "Density Test locations only; see plan for test locations Direct Shear Tests Location & Depth Pit 2 @ 4' Undisturbed-Saturated 31 Pit 5 @ 9' 90 Undisturbed-Natural 33 200 Pit 7 @ 0.5' Remolded-Saturoted 29 90 Angle of Internal Cohesion Sample Condition Friction @,degrees) (Ibs/q .ft) Moisture PACIFIC SOILS ENGINEERINQ. INC. August 26, 1975 Work Order 100407 Expansion Tests Soil Type % Swell * A - Sand 0.0 * Sample remolded to 90 percent of laboratory standard; 650 p.s.f. surcharge from optimum moisture to saturation. Consolidation Tests See Plates 51 and &2 PACIFIC SOILS ENGINEERING, INC. 3 W.O. 1 004 07 ULTIMATE BEARING CAPACITY 11 RADIAL SHEAR ACTIVE PRESSURE TERZAGHI FORMULA qu 9 C( N,) + ,b(+N.) +Id (N *) = 9,930 b * Footing Width - 1.0 d Surcharge' Depth - 1.0 * 'r = Unit Weight of Soi I = 130 9 = Angle of Infernal Friction = 33 c = Cohesion = 110 N, .N,.Nq = Bearing Factors Dependent on + .I Nc - 38.6" Nr- 35.2 Nq 26.1 *See page 6, item 1 for bearing capacity recommendations **Values for import material, per referenced report. soil TYPe COMPACTED FILL Ibs/sq. ft. * 11. fl . Ibdcu. ft.** degrees ** Ibs/sq. ft. ** PACIFIC SOILS ENGINEERING, INC. PLATE "C"