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HomeMy WebLinkAboutCT 01-17; TAMARACK FIVE; GEOTECHNICAL EXPLORATION RPT AND GRADING PLAN; 2001-12-136^ DECEMBER 13, 2001 PROJECT NO. 01-5421 GEOTECHNICAL EXPLORATION REPORT AND GRADING PLAN REVIEW PROPOSED RESIDENTIAL DEVELOPMENT (5 LOTS) 625 TAMARACK AVENUE CARLSBAD CALIFORNIA FOR MANNING HOMES 20151 SOUTH WEST BIRCH STREET, SUITE 150 NEWPORT BEACH, CALIFORNIA 92660-1713 OILS ENGINEERING, INC. OXO f'/^ CORPORATE: 3320 AIRPORT WAY - LONG BEACH, CALIF. 90806 - PHONE 562/426-7990 - FAX 562/426-1842 SAN DIEGO: 9235 CHESAPEAKE DR. - SAN DIEGO, CALIF. 92123 - PHONE 858/974-3691 - FAX 858/974-3752 SINEERING.INC. Consulting Foundation Enginmr* December 13, 2001 Project No. 01-5421 Manning Honnes 20151 South West Birch Street, Suite 150 Newport Beach, California 92660-1713 Attention: Mr. Peter Hemphill Subject: Geotechnical Exploration Report and Grading Plan Review Proposed Residential Development (5 Lots) 625 Tamarack Avenue Carlsbad, California Gentlemen: Presented herewith is our Geotechnical Exploration Report for the proposed residential development which is to be constructed at the above subject address. The work was conducted in accordance with our proposal dated May 18, 2001 (reissued November 9, 2001), and your subsequent authorization on November 16, 2001. The exploration was planned and performed utilizing the information provided by you as to the proposed future development of the site. Provided information included a Tentative Subdivision Map for the property prepared by BHA Inc., undated, and enclosed herein as Plate A. Engineering evaluation for site conditions has been made with regard to the geotechnical aspects of the planned residential development. Our evaluation indicates that the proposed residential structures may be supported on shallow conventional foundations bearing on approved compacted fill. Presented within this report are geotechnical criteria for site grading, design and construction of the proposed structures on shallow conventional foundations. We thank you for the opportunity of working with you on this project. We look fonA/ard to assisting you during site grading and foundation construction. If you have any questions or require additional information, please contact the undersigned. Respectfully submitted, ASSOCIATED SOILS ENGINEERING, INC. Ed ware Engineering Geolc^ GLM/LFA/ECR:cmc Distribution: (4) Addressee L. Fernando AragonJ^.E. GE-99 Geotechnical Engineer OILS ENGINEERING, INC. 1.0 INTRODUCTION This report presents the results of our geotechnical exploration for the proposed development of five (5) single-family detached homes to be located at 625 Tamarack Avenue in Carlsbad, California. The approximate location of the site is shown on the Site Location Map (Figure 1). The purpose of the exploration was to evaluate the general soil conditions at the site, including evaluation of the site specific liquefaction potential, and provide geotechnical recommendations for the design and construction of the proposed project. 1.1 PROJECT DESCRIPTION The following information provided by project consultants is currently understood to apply to this project. 1.1.1 Building Concepts: It is our understanding that existing site structures are to be razed and the site regraded to accommodate five (5) residential lots along with an associated cul-de-sac. The proposed residential structures are presumed to consist of one and two-story frame construction supported by shallow conventional foundations, and with interior slabs-on- grade. 1.1.2 Structural Loading: In the absence of actual structural loading information, we will assume that the maximum column load will be on the order of 25 kips. Maximum load on continuous footings will be assumed to be less than 2500 pounds per linear foot. 1.2 SCOPE OF EXPLORATION In order to accomplish the purpose of this exploration, our scope of work included the performance of the following tasks: A. Review of available project data and preparation of an exploration program. B. Field exploration consisting of drilling four (4) borings to depths of 25 to 40 feet below existing grades, field logging of borings and soil sampling. Manning Homes December 13, 2001 OILS ENGINEERING, INC. 01-5421 Pagel ProjectNo.: 01-5421 SITE LOCATION MAP FIGURE 1 C. Laboratory testing of selected soil samples to aid in the classification of the materials sampled and to determine their engineering properties. D. Interpretation, analysis and evaluation of the data obtained and preparation of this report presenting recommendations for foundation design and construction. The results of field exploration and laboratory testing upon which our evaluation and recommendations are based are presented in the Appendices to this report. This exploration did not include any evaluation or assessment of hazardous or toxic materials, which may or may not exist on or beneath the site. 2.1 SITE AND SUBSURFACE CONDITIONS 2.1 LOCATION The site is located at 625 Tamarack Avenue in the City of Carlsbad, California, and is legally described as a portion of Tract 232 of Thums Land in the City of Carlsbad, County of San Diego, State of California, according to Map thereof No. 1681, filed in the Office of the County Recorder of San Diego County, December 9, 1915. The following information pertaining to site conditions was obtained during the course of performing field work for this project. 2.2 BOUNDARY CONDITIONS Tamarack Avenue is north of the property, with the Dolphin Beach Apartments and an asphalt parking lot for the apartment complex beyond. A single-family residence and undeveloped property are south and west of the site. Single-family residences bound the site to the east. 2.3 EXISTING DEVELOPMENT The site surface is generally uniform and level. The majority of the site has been used for agricultural purposes, with furrowed rows from previous and current plantings. Manning Homes December 13, 2001 01-5421 Page 2 OILS ENGINEERING, INC. A single-story frame and stucco residence and a converted garage/office are present is the southerly portion of the site. Portland cement concrete walks are located around the residence. The existing flatwork visually appears to be in fair condition. A small wood frame commercial flower shack is located on-site along Tamarack Avenue. Several medium-size trees, small palms, fruit trees, grape vines, tomato plants and other planted crops are present within the property. Tree stumps were also noted in the southerly portion of the site. Planters are located around the existing residence. 2.4 SUBSURFACE CONDITIONS Subsurface exploration disclosed the presence of shallow fill soils at one (1) of the four (4) boring locations drilled for this project. Fill soils (or disturbed native soils) were encountered to a depth on the order of 15-inches below existing grade in Boring B-2. Encountered fill soils consist of silty sands, and contain metal pipe pieces. Site native soils are Quaternary Age Terrace Deposits (Map Symbol -Qt) and consist predominantly of silty sands, silty sands with clay, sands with silt, and sands, with some sandy silt with clay layers. The soils were, in general, damp to moist, with some layers very moist. Standard Penetration Test ("N" Value) and barrel sampler blow counts indicate that native granular soils are in a medium dense to very dense condition. More detailed descriptions of the soils encountered and conditions observed during the subsurface exploration are shown in the boring logs in the Appendix A. Included in the logs are the depth of soil samples, Standard Penetration Test ("N" Value) and barrel sampler blow counts, field dry densities and field moisture contents. 2.4 GROUNDWATER AND CAVING During field exploration, groundwater was encountered at a depth of approximately 34 feet below existing grade in Boring B-4. Manning Homes December 13, 2001 01-5421 Pages OILS ENGINEERING, INC. Generally, seasonal and long-term fluctuations in the groundwater may occur as a result of variations in subsurface conditions, rainfall, run-off conditions and other factors. Therefore, variations from our observations may occur. The use of hollow-stem augers during drilling precluded observation of potential caving conditions which may have otherwise occurred in an uncased hole. Caving and/or sloughing in the test borings was not determined during the extraction of auger stem at the completion of boring operations. Caving may be likely in excavations greater in dimension than our test borings. 2.5 UTILITIES No overhead or underground utilities were encountered during the course of our field work for this project. However, overhead and underground utility lines provide service to existing site structures. Overhead lines are along the easterly property line. 3.0 REGIONAL SEISMICITY 3.1 FAULTING AND SURFACE RUPTURE HAZARD The subject site is not located within an Alquist-Priolo Earthquake Fault Zone. No known active or potentially active faults are shown crossing the site on published maps reviewed (Jennings, 1994). Therefore, the risk of surface rupture at the site is considered low. However, being in close proximity to several known active and potentially active faults, severe ground shaking should be expected during the life of the proposed structures. There are a number of faults in the Southern California area which are considered active and could have an effect on the site in the form of moderate to strong ground shaking, should they be the source of an earthquake. These faults include, but are not limited to, the San Andreas fault, the San Jacinto fault, the Whittier-Elsinore fault and the Newport- Inglewood fault zone. The Rose Canyon Fault is closest to the site, approximately 4.6 miles away. Manning Homes December 13, 2001 01-5421 Page 4 OILS ENGINEERING, INC. 3.1 LIQUEFACTION POTENTIAL The term "liquefaction" describes a phenomenon in which a saturated cohesionless soil loses strength and acquires a degree of mobility as a result of strong ground shaking during an earthquake. The factors known to influence liquefaction potential include soil type and depth, grain size, relative density, groundwater level, degree of saturation, and both the intensity and duration of ground shaking. Clayey soils are generally not susceptible to liquefaction. Also, based on published case histories, liquefaction of soils deeper than about 45 feet depth appears unlikely. During our field exploration, groundwater was encountered in Boring B-4 at a depth of approximately 34 feet below existing grade. The soils to the 40 feet maximum depth drilled consist predominantly of dense to very dense granular soils, with some medium dense near surface layers. Based on available geotechnical data obtained during this exploration, it is our opinion that the potential for liquefaction as a result of ground shaking at the site is low. 4.0 RECOMMENDATIONS Based on the results of our field exploration and laboratory testing, combined with engineering analysis and our experience and judgment, it is the opinion of ASE that the site may be developed as planned, provided the site grading and foundation criteria discussed herein are incorporated into the project plans and specifications and implemented during construction. The major geotechnical considerations affecting the design and construction of the residential development include the following: 1. Soil disturbance as a result of site demolition and clearing operations. 2. Presence of existing fill soils in some areas of planned construction. It is our opinion that overexcavation and backfilling with properly compacted fill in the building areas as recommended herein, will be necessary to reduce structure settlements and provide satisfactory performance of the buildings. The grading recommendations provided herein are Manning Homes December 13, 2001 01-5421 Page 5 OILS ENGINEERING, INC. specific to the presently proposed grading and should be reviewed if final project concept and grading plans are changed. It is currently proposed to reconfigure the site to accommodate five (5) single family residences on individual building pads, access road and parkways. Cuts and fills are planned at up to one to five feet, respectively. The recommendations provided herein apply to conventional foundations comprised of continuous and spread footings. 4.1 SITE PREPARATION 4.1.1 Existing Improvements: Prior to grading operations, it will be necessary to remove designated existing construction, including any remaining buried obstructions, which may be in the areas of proposed construction. Structure removal should include foundations. Concrete flatwork should also be stripped from the site. Concrete fragments from site demolition operations should be disposed of off-site. 4.1.2 Surface Vegetation: Surface vegetation should be stripped from areas of proposed construction. Stripping should penetrate three to six inches into surface soils. Any soils contaminated with organic matter (such as root systems or strippings mixed into the soils) should be disposed of off-site or set aside for future use in landscaping areas. Removal of trees and shrubs should include rootballs and attendant root systems. 4.1.3 Underground Utilities: Any underground utilities to be abandoned within the zone of proposed construction should be cut off a minimum of 5 feet from the area of the future construction. The ends of cut off lines should be plugged a minimum of 5 feet with concrete exhibiting minimum shrinkage characteristics to prevent water migration to or from hollow lines. Capping of lines may also be required should the plug be subject to any line pressure. Manning Homes December 13, 2001 01-5421 Pagea OILS ENGINEERING, INC. As an alternate, deep hollow lines may be left in place, provided they are filled with concrete. No filled line should be permitted closer than 2 feet from the bottom of future footings. Local ordinances relative to abandonment of underground utilities, if more restrictive, will supersede the above minimum requirements. 4.2 SITE GRADING 4.2.1 Old Fill/Disturbed Native Soils: All old undocumented fill soils should be excavated full depth. Any native soils disturbed during demolition and clearing operations should also be excavated full depth. Lateral extent of overexcavation beyond structure perimeters, where possible, should be to a minimum distance equal to the depth of fill/loose soil encountered or three feet, whichever is greater. The exposed excavation bottoms should be scarified to a minimum one foot depth and recompacted to a minimum of 90 percent relative compaction at near optimum moisture content prior to backfilling with approved soils as specified in Section 4.2.7 below. 4.2.2 Remedial Grading: To provide acceptable support for structure foundations and slabs, it is recommended that the native soils be overexcavated to a minimum depth of three feet below existing or proposed grade, whichever is deeper, and replaced with properly compacted fill such that the building footings and slabs are supported on an improved layer of approved compacted fill. It will be necessary to provide a minimum three feet of approved compacted fill beneath existing grade or finish grade, whichever is lower, in all areas of building interior slab-on- grade construction. Approved fill material in areas of interior slabs-on-grade should consist predominantly of granular material (Expansion Index less than 20). Granular soils Manning Homes December 13, 2001 01-5421 Page? 50ILS ENGINEERING, INC. should be recompacted to a minimum of 90 percent relative compaction at near optimum moisture content. The overexcavation should extend laterally beyond footing edges to a distance equivalent to the depth of overexcavation below footings, and to a minimum of three feet beyond building perimeters, where possible. A six-inch scarification and recompaction of in-place soils to 90 percent relative compaction at near optimum moisture content may be taken equivalent to six-inches of approved compacted fill, when computing total excavation requirements. The depth of overexcavation should be reviewed by the Geotechnical Consultant during the actual construction. Any subsurface obstruction, buried structural elements, and unsuitable material encountered during grading, should be immediately brought to the attention of the Geotechnical Consultant for proper exposure, removal and processing, as recommended. Exposed excavation bottoms should be observed by the Geotechnical Consultant or his representative. 4.2.3 Excavation Procedures: Excavations of site soils 4 feet or deeper should be temporarily shored or sloped in accordance with Cal OSHA requirements. a) Temporary Slopes: In areas where excavations deeper than 4 feet are not adjacent to existing structures or public right-of-ways, sloping procedures may be utilized for temporary excavations. It is recommended that temporary slopes in native soils be graded no steeper than 1.5:1 (H:V) for excavations up to 10 feet in depth. The above temporary slope criteria is based on level soil conditions behind temporary slopes with no surcharge loading Manning Homes December 13, 2001 01-5421 Pages OILS ENGINEERING, INC. (structures, traffic) within a lateral distance behind the top of slope equivalent to the slope heighL It is recommended that excavated soils be placed a minimum lateral distance from top of slope equal to the height of slope. A minimum setback distance equivalent to the slope height should be maintained between the top of slope and heavy excavating/grading equipment. Soil conditions should be reviewed by the Geotechnical Consultant as excavation progresses to verify acceptability of temporary slopes. Final temporary cut slope design will be dependent upon the soil conditions encountered, construction procedures and schedule. b) Shoring: Temporary shoring will be required for those excavations where temporary slope cuts as specified above are not feasible. Temporary cantilever shoring, if used, should be designed to resist an active earth pressure of 45 pounds per cubic foot equivalent fluid pressure for level conditions behind shoring. The design of shoring should also include surcharge loading effects of existing structures and anticipated traffic, including delivery and construction equipment, when loading is within a distance from the shoring equal to the depth of excavation. In addition to the above, a minimum uniform lateral pressure of 100 pounds per square foot in the upper ten feet of shoring should be incorporated in the design when normal traffic is permitted within ten feet of the shoring. Manning Homes December 13, 2001 01-5421 Page 9 OILS ENGINEERING, INC. 4.2.4 Exterior Concrete Flatwork and Pavement Support: It will be necessary to provide a minimum one foot of approved compacted fill beneath existing grade or finish grade, whichever is lower, in all areas of exterior concrete flatwork, as well as asphalt pavement areas. Site soils should be recompacted to a minimum 90 percent relative compaction at near optimum moisture contents. A six-inch scarification and recompaction of in-place soils to 90 percent relative compaction at near optimum moisture contents may be taken equivalent to six-inches of approved compacted fill, when computing total excavation requirements. 4.2.5 New Fills: The upper one foot of site soils should be excavated and recompacted to a minimum of 90 percent relative compaction prior to placement of any new fills, where required, to achieve finish grade elevations. The exposed excavation bottoms should be scarified a minimum one foot and recompacted to at least 90 percent relative compaction at near optimum moisture contents. The excavation bottom should be firm and unyielding prior to backfilling. 4.2.6 Imported Soils: Any imported soil required to complete grading operations should consist of predominantly granular material which exhibits an expansion index less than 20 when tested in accordance with U.B.C. 18-2 Expansion Test Procedures, and should be free of debris, particles greater than 4 inches in maximum dimension, organic matter or other deleterious materials, and should be approved by the Geotechnical Consultant or his representative. 4.2.7 Backfilling and Compaction Requirements: Existing site soils, unless indicated otherwise, are considered suitable for re-use during site grading and backfilling of utility trenches, provided they are free of debris, particles greater than 4 inches in maximum dimension, organic matter or other deleterious Manning Homes December 13, 2001 01-5421 Page 10 SOILS ENGINEERING, INC. materials, and are to a suitable moisture condition to permit achieving the required compaction. On-site and import materials approved for use should be placed in horizontal lifts not exceeding 8-inches in loose thickness, moisture conditioned to near optimum moisture contents, and compacted to a minimum of 90 percent of the maximum dry density as determined by ASTM Test Method Dl 557-91. 4.2.8 Tests and Observations: All grading, compaction, and backfill operations should be performed under the observation of and testing by the Geotechnical Consultant's representative. An adequate number of field tests should be taken to ensure compliance with this report and local ordinances. If it is determined during grading that site soils require overexcavation to greater depths for obtaining proper support for the proposed structures, this additional work should be performed in accordance with the recommendations of the Geotechnical Consultant. Imported fill soils should be examined by a representative of the Geotechnical Consultant, and tested as necessary for evaluating their suitability for use as fill prior to being hauled to the site. Final acceptance of any imported soil will be based upon review and testing of the soil actually delivered to the site. Maximum density for control of grading should be determined in accordance with ASTM Dl 557-91 test procedures. 4.3 FOUNDATION DESIGN It is our opinion that conventional continuous and spread footings bearing on approved compacted fill may be used to provide support for the proposed residential development construction at the subject site. Presented below are the recommended geotechnical criteria for the design of footings. Manning Homes December 13, 2001 01-5421 Pagell OILS ENGINEERING, INC. 4.3.1 Bearing Capacities: Dead plus live load allowable soil bearing pressures of 2200 and 2500 pounds per square foot may be used in the design of continuous and spread footings, respectively, when supported on approved compacted fill in accordance with recommendations in Section 4.2.2. Recommended minimum footing width is one foot. The above bearing pressures may be increased by one-third under short term loading from wind or seismic forces. 4.3.2 Footing Embedment and Reinforcement: Recommended minimum footing embedment is 18 inches below lowest adjacent finish soil grade, with minimum reinforcement of one #4 for top and bottom of the footings. Foundation design details such as concrete strength, reinforcements, etc. should be established by the Project Structural Engineer. 4.3.3 Settlements: Total settlements for foundations designed and constructed in accordance with the above criteria, and supporting maximum assumed column and wall loads of 25 kips and 2.5 kips per linear foot, respectively, are not anticipated to exceed one inch. A differential settlement on the order of 1/4 inch is anticipated between similarly loaded pad footings and for continuous wall footings over a distance of approximately 30 feet. A differential settlement on the order of 1/4 inch is anticipated between adjacent column and wall footings supporting the assumed structural loads. This office should be contacted for further evaluation and recommendations, as necessary, should final design structural loads exceed the maximum loads used in our analysis by more than 10 percent. Manning Homes December 13, 2001 01-5421 Page 12 OILS ENGINEERING, INC. 4.3.4 Lateral Resistance: Resistance to lateral loads can be assumed to be provided by passive earth pressure and by friction acting on structural components in permanent contact with the subgrade soils. Lateral resistance on the sides of footings may be computed using a passive pressure of 250 pounds per square foot perfoot of embedment into properly compacted fill, subject to a maximum of 2500 pounds per square foot. An ultimate friction coefficient of 0.4 may be assumed with dead load forces between concrete and the supporting soils. 4.3.5 Retaining Walls: Any retaining walls planned should be adequately designed to resist the lateral soil pressures and the anticipated construction loadings and service conditions. The earth pressure acting on retaining walls depends primarily on the allowable wall movement, type of backfill materials, backfill slopes, wall inclination, surcharges, and any hydrostatic pressure. The following equivalent fluid pressures are recommended for vertical walls with no hydrostatic pressure and no surcharge loading: EARTH PRESSURE Backfill Slope Equivalent Fluid Pressure (pcf) Soil Tvpe Behind Walls Active (Cantilever) At-Rest (Rigid) Silty Sands Level 40 60 These values are applicable for site soils placed between the wall stem and an imaginary plane rising at 45 degrees from below the edges (heel) of wall footings. The surcharge effect of anticipated loads on the wall backfill (e.g., traffic, construction equipment, footings) should be included in the wall design. Depending on whether the wall is free to deflect or restrained, 33 or 50 percent, respectively, of a maximum surcharge load located within a distance equal to the retained height of the wall should be used in design. Manning Homes December 13, 2001 01-5421 Page 13 SOILS ENGINEERING, INC. Positive drainage measures should be incorporated in design. Consideration should be given to the use of a drainage system at the base of retaining walls to intercept any seepage should it develop at some time following construction. Alternately, weep holes may be provided to relieve any hydrostatic pressure build-up, where feasible, with suitable collection and discharge points. 4.3.6 Footing Observation: All footing excavations should be observed by the Geotechnical Consultant's representative to verify minimum embedment depths and competency of bearing soils. Such observations should be made prior to placement of any reinforcing steel or concrete. 4.4 SEISMIC DESIGN PARAMETERS The following seismic design parameters are provided based on review of data obtained from our recent geotechnical exploration, and review of available literature from the California Division of Mines and Geology, and the US Geological Survey. 1997 UBC Indicated Value or Chapter 16 Table # Seismic Parameter Classification 16-1 Seismic Zone Factor 0.40 16-J Soil Profile Type SD 16-Q Seismic Coefficient Ca 0.44 Na 16-R Seismic Coefficient Cv 0.64 Nv 16-S Near-Source Factor Na 1.0 16-T Near-Source Factor Nv 1.2 16-U Seismic Source Type B Final selection of design coefficients should be made by the structural consultant based on the local laws and ordinances, expected building response, and desired level of conservatism. The nearest fault to the site is the Rose Canyon Fault located approximately 4.6 miles away. OILS ENGINEERING, INC. Manning Homes December 13, 2001 01-5421 Page 14 4.5 EXPANSIVE SOILS Site subgrade soils exhibit a very low soil expansion potential as defined in Table No. 18- 1 B "Classification of Expansive Soils" in the Uniform Building Code, 1997 Edition. It is our opinion that for site conditions, soil expansion may not be a critical factor in design. The degree of soil expansion should be confirmed by additional tests during or after rough grading operations. 4.6 SITE DRAINAGE Surface grades adjacent to buildings should be designed and constructed to facilitate drainage away from structures. Recommended minimum grade in unpaved areas around buildings and asphalt-paved areas is 2 percent, and in concrete paved areas is 1 percent. Any planter areas placed adjacent to perimeter footings should be provided with solid bottoms and a drainage pipe, or other devices to divert water away from foundation and slab subgrade soils. Excessive moisture variations in such soils could result in significant volume changes and movement. 4.7 SLAB-ON-GRADE Concrete floor slabs in buildings and exterior concrete flatwork should be supported on properly compacted soils as recommended in the Site Grading section of this report. Any interior slab to receive a moisture sensitive floor covering should be underlain by an impermeable membrane (minimum 8 mil thick visqueen) topped with two inches of clean, coarse sand. As a minimum, slabs should be 4-inches thick and reinforced with #3 reinforcing bars spaced at 30-inches on center. The slab subgrade should be proof-rolled just prior to construction to provide a firm, unyielding surface, especially if the subgrade has been disturbed or loosened by the passage of construction traffic. Final compaction and testing of slab subgrade should be performed just prior to placement of concrete. Manning Homes December 13, 2001 01-5421 Page 15 SOILS ENGINEERING, INC. Interior and exterior slabs should be properly designed for the construction and service loading conditions. The structural details, such as slab thickness, concrete strength, amount and type of reinforcements, joint spacing, etc., should be established by the Project Structural Engineer. 4.8 SOLUBLE SULFATES A sample of selected subgrade soil was tested to determine the concentration of water- soluble sulfates. Laboratory testing indicated a sulfate concentration of 0.004 percent by weight of dry soils in the tested soil sample. Soils with sulfate concentrations less than 0.10 percent are generally reported to have a negligible corrosive effect on concrete as defined on Table 19-A-4 of the U.B.C, 1997 Edition. All concrete in contact with site soils should comply with Table 19-A-4 of the U.B.C, 1997 Edition for negligible sulfate exposure. 4.9 UTILITY TRENCHES Bedding material should consist of sand with a Sand Equivalent value not less than 30. Backfill of all trenches should be compacted to achieve a relative compaction of not less than 90 percent, in accordance with ASTM Dl 557-91. Care should be taken during backfilling to prevent utility line damage. The walls of temporary construction trenches may not be stable when excavated nearly vertical due to the potential for caving. Shoring of excavation walls or flattening of slopes will be required for temporary excavations deeper than 4 feet. Trenches should be located so as not to impair the bearing capacity of soils or cause settlement under foundations. As a guide, trenches parallel to foundations should be clear of a 45-degree plane extending outward and downward from the edge of the foundations. Manning Homes December 13, 2001 01-5421 Page 16 SOILS ENGINEERING, INC. All work associated with trenches, excavations and shoring must conform to the State of California Safety Code. 4.10 PLAN REVIEW. OBSERVATIONS AND TESTING All excavations should be observed by a representative of this office to verify minimum embedment depths, competency of bearing soils and that the excavations are free of loose and disturbed materials. Such observations should be made prior to placement of any fill, reinforcing steel or concrete. All grading and fill compaction should be performed under the observation of and testing by the Geotechnical Consultant or his representative. As foundation and grading plans are completed, they should be forwarded to the Geotechnical Consultant for review for conformance with the intent of these recommendations. 5.0 CLOSURE This report has been prepared for the exclusive use of the Manning Homes and their design consultants relative to the design and construction of the proposed residential development at the subject site. The report has not been prepared for use by other parties, and may not contain sufficient information for purposes of other parties. The Owner or their representatives should make sure that the information and recommendations contained in this report are brought to the attention of the project engineers and architects and incorporated into the plans, and that the necessary steps are taken to confirm that the contractors carry out such recommendations in the field. This office should be notified should any of the following, pertaining to the final site development, occur: 1. Final plans for site development indicate utilization of areas not originally proposed for construction. Manning Homes December 13, 2001 01-5421 Paget? OILS ENGINEERING, INC. 2. Structural loading conditions vary from those utilized for evaluation and preparation of this report. 3. The site is not completed within 12 months following the date of this report. 4. Change of ownership. Should any of the above occur, this office should be notified and provided with finalized plans of site development for our review to enable us to provide the necessary recommendations for additional work and/or updating of the report. Any charges for such review and necessary recommendations would be at the prevailing rate at the time of performing review work. The findings contained in this report are based upon our evaluation and interpretation of the information obtained for the limited number of test borings and the results of the laboratory testing and engineering analysis. As part of the engineering analysis it has been assumed, and is expected, that the geotechnical conditions which exist across the site are similar to those encountered in the test excavations. However, no warranty is expressed or implied as to the conditions at locations or depths other than those excavated. Should any conditions encountered during construction differ from those described herein, this office should be contacted immediately for recommendations prior to continuation of work. Our findings and recommendations were obtained in accordance with generally accepted current professional principles and local practice in geotechnical engineering and reflect our best professional judgment. We make no other warranty, either express or implied. These findings and recommendations are, however, dependent on the above assumption of uniformity and upon proper quality control of fill placed and foundations installed. Geotechnical observations and testing should be provided on a continuous basis during grading at the site to confirm design assumptions and to verify conformance with the intent of our recommendations. If parties other than Associated Soils Engineering, Inc., are engaged to provide services during construction they must be informed that they will be required to assume complete responsibility for the geotechnical phase of the project by concurring with the recommendations in this report or providing alternative recommendations. Manning Homes December 13, 2001 01-5421 Page 18 OILS ENGINEERING, INC. This concludes our scope of services as indicated in our proposal dated May 18, 2001 (reissued November 9, 2001), however, our report is subject to review by the controlling authorities for the project. Any further geotechnical services that may be required of our office to respond to questions/comments of the controlling authorities after their review of the report will be performed on a time and expense basis as per our current fee schedule. We would not proceed with any response to report review comments/questions without authorization from your office. We appreciate your business and hope that we can assist you during construction related service. 6.0 REFERENCES Blake, 1995, EQFAULT, a Computer Program for the Deterministic Prediction of Horizontal Acceleration of Digitized California Faults, IBM-PC Version, User's Manual Jennings, C.W., 1994, Fault Activity Map of California and Adjacent Areas, Scale 1:750,000, California Division of Mines and Geology, California Data Map Series, Map No. 6. crJc^^,r,Lcol>r rMr Manning Homes December 13, 2001 SOILS ENGINEERING, INC. ^^^l Page 19 APPENDIXA The following Appendix contains the substantiating data and laboratory test results to complement the engineering evaluations and recommendations contained in this report. Plate A Boring Location Plan Plates B-1 through B-4 Logs of Borings Plates C-1 through C-3 Consolidation Test Results Plates D-1 through D-3 Direct Shear Tests SITE EXPLORATION On November 26, 2001, field explorations were performed by drilling four (4) test borings at the approximate locations indicated on the attached Boring Location Plan, Plate A. Exploratory borings were drilled by C & C Drilling Company, utilizing a truck mounted, rotary drilling rig equipped with 8-inch diameter continuous flight, hollow-stem rotary augers. The borings extended to depths ranging from 25 to 40 feet from existing grades. Continuous observations of the materials encountered in the borings were recorded in the field. The soils were classified in the field by visual and textural examination and these classifications were supplemented by obtaining bulk soil samples for future examination in the laboratory. Relatively undisturbed samples of soils were extracted in a barrel sampler lined with 2.375-inch diameter by one-inch rings and tipped with a tapered cutting shoe. Additional samples were obtained in a Standard Penetration sampler in accordance with specifications outlined in ASTM D1586. All samples were secured in moisture-resistant bags as soon as taken to minimize the loss of field moisture while being transported to the laboratory and awaiting testing. Upon completion of exploration, the borings were backfilled with excavated materials and compacted by tamping. Description of the soils encountered, depth of samples, field density and field moisture content of tested samples, and Standard Penetration Test ("N" Values) and barrel sampler blow counts are given on the Logs of Borings (see attached "B" Plates). ^ ^ ' ~ ^ ^ Manning Homes December 13, 2001 SOILS ENGINEERING. INC. ^^,5421 Page 20 /A FIELD LOG OF BORING B - 1 Sheet 1 of 2 /A Project: New Residential Devopment (5 Lots)-Carlsbad SOILS ENGINEERING, INC. Location: 625 Tamarack Avenue Project No. 01-5421 Dates(s) Drilled: Drilled By: Rig Make/Model: Drilling Method: Hole Diameter: 11/26/01 C&C Drilling Company Mobile B-61 Hollow-stem Auger 8 In. Logged By: Gary Martin Total Depth: 25 Feet Hammer Type: Wireline downhole Hammer Weight/Drop: 140 Lb./±30 In. Surface Elevation: Unknown Comments: No groundwater. Q. LU Q CO UJ ^ _1 UJ SAMPLE INTERVALS UJ b Q. > (3 O _i O X 03 O CO 3 GEOTECHNICAL DESCRIPTION o Q. CO >- z cc UJ Q Q UJ CC Z) t-co o z LU H Z o o CO H CO UJ I- tr UJ X H o 5 —5 10 10 |1 6/6"(Ring) m 17/6"(Ring 46(Rlng) I 50/6"(Ring; SM SM SM JL SM SM SP-SM SILTY SAND: Dark brown,molst,fine- grained sand SILTY SAND: Dark yellowish brown,moist,fine-grained sand,trace clay SILTY SAND WITH CLAY: Dark yellowish brcwn.moist.fine-grained sand SILTY SAND: Ught dive brown,damp,fine- grained sand \ 'insufficient sample for density SILTY SAND: Yellowish brown,moist,fine- grained sand,trace clay SAND WITH SILT: Olive yellow,moist,fine- grained sand +nioisture sample from upper 6" of SPT 112.0 117.0 123.2 9.3 11.2 10.9 * 5 8 105.0 8:4 13.0 MAX,EXP,S04 REMOLD SHEAR /A FIELD LOG OF BORING B - 1 Sheet 2 of 2 /A Project: New Residential Devopment (5 Lots)-Carlsbad SOILS ENGINEERING, INC. Lcx:ation: 625 TamaracAr Avenue Project No. 01-5421 a. UJ Q z O < CO —I Ul SAMPLE INTERVALS A >-CD O _i O X CO o CO 3 GEOTECHNICAL DESCRIPTION o Q. CO > z cn lu Q Q Q o 2 o Ol CO H CO m H 01 UJ X 15 15 20 25 20 25 I 54(SPT) • 50/5"(Ring; I 82/10" (SPT) SM SM SM SILTY SAND: Ught yellowish brown,very moist to wet,fine^rained sand SILTY SAND WITH CLAY: Pale yellow to light gray,moist,fine to coarse-grained sand same as above 26.6 111.6 i 11.1 11.7 SOILS ENGINEERING, INC. FIELD LOG OF BORING B Sheet 1 of 2 Project: New Residential Devopment (5 Lots)-Carlsbad Location: 625 Tamarack Avenue Project No. 01-5421 Dates(s) Drilled: Drilled By: Rig Make/Model: Drilling Method: Hole Diameter: 11/26/01 C&C Drilling Company Mobile B-61 Hollow-stem Auger 8 In. Logged By: Gary Martin Total Depth: 25 Feet Hammer Type: Wireline downhole Hammer Weight/Drop: 140 Lb./±30 In. Surface Elevation: Unknown Comments: No groundwater. X h-Q. UJ Q UJ UJ CO SAMPLE INTERVALS UJ b a. CD O _i O X CO o CO GEOTECHNICAL DESCRIPTION sr-o a. CO >- z cc in a Q Q o UJ CO h-CO UJ H CC lU X 10 10 1 1 SM SILPi' SAND: FILL-Brown,damp,fine- grained sand,with metal pipe pieces i • 82/8" P (Ring) i-z-z- SM SILTY SAND: NATIVE-Yellowish brown,damp,fine-grained sand 105.7 3.4 i • 82/8" P (Ring) SM SILTY SAND WITH CLAY: Yellowish brown,moist,fine-grained sand • 51(SPT) _ \~_ _ _ .\"_ •_ .x~"_ 8.1 _ \~._ _ \~_ " " \~ • .\~ " _ .\-_ "_ \-_ - .- -r- -z~z-z SM SILTY SAND: Ught olive brown.damp.fine- grained sand • 53(Ring) 108.2 6.4 • 53(Ring) -z-z-z J J j m r \ SP-SM SAND WITH SILT: Pale olive,trace brownish yellow,damp to moist,fine-grained sand 1 23/6"(Ring 4 104.8 7.3 SHEAR CONSOL SOILS ENGINEERING, INC. FIELD LOG OF BORING B Sheet 2 of 2 Project: New Residential Devopment (5 Lots)-Carisbad Location: 625 Tamarack Avenue Project No. 01-5421 X H Q. UJ Q Z o < CO UJ SAMPLE INTERVALS >-CD O _i O X CO o CO 3 GEOTECHNICAL DESCRIPTION o Q. CO >- z cc m Q Q UJ ^ i= O o 2 o LU so CO H CO m I- cc UJ X h-o 15 — 15 20 20 25 25 50/6"(Ring] 65(SPT) I SP SM 50/6"{Ring; SM SAND: Paie olive,trace brownish yellow.moist to very moist,fine to medium- grained sand.trace silt 103.5 SILTY SAND WITH CLAY: Pale yellow to light gray,moist,fine to medium-grained sand SILTY SAND: Pale olive with white,mojst,fine to coarse-grained sand,trace clay 112.2 V 17.8 14.3 13.0 fA FIELD LOG OF BORING B - 3 Sheet 1 of 2 fA Project: New Residential Devopment (5 Lots)-Carlsbad SOILS ENGINEERING, INC. Location: 625 Tamarack Avenue Project No. 01-5421 Dates(s) Drilled: Drilled By: Rig Make/Model: Drilling Method: Hole Diameter: 11/26/01 C&C Drilling Company Mobile B-61 Hollow-stem Auger 8 In. Logged By: Gary Martin Total Depth: 25 Feet Hammer Type: Wireline downhole Hammer Weight/Drop: 140 Lb./±30 In. Surface Elevation: Unknown Comments: No groundwater. X H Q. UJ Q % HI _1 UJ CO SAMPLE INTERVALS UJ b ^ > CD O _i O X CO o CO 3 GEOTECHNICAL DESCRIPTION o CO >- z cc UJ Q Q UJ CC I- co O z m O o UJ CO H CO UJ H CC LU X 0 -r-0 5 ^5 10 -h 10 26(Ring) 50/5"(Ring;i- 37(SPT) SM SM SM I 72(Ring) SP SILTY SAND: Dari< yellowish brown.damp.fine-grained sand 118.0 SILTY SAND: Yellowish brown,moist,fine- grained sand.trace clay SILTY SAND: Ught dive brown.damp to mdst.fine to medium-grained sand 121.6 SAND: Olive yellow with brownish yellow,damp,fine to medium-grained sand,trace silt 6.4 8.1 7.5 109.9 i 3.6 CONSOL SOILS ENGINEERING, INC. FIELD LOG OF BORING B Sheet 2 of 2 Project: New Residential Devopment (5 Lots)-Carlsbad Lcx:ation: 625 Tamarack Avenue Project No. 01-5421 LL X h-o. UJ Q < CO UJ SAMPLE INTERVALS >- CD O _i o X CO o CO ZD GEOTECHNICAL DESCRIPTION CL CO >- _ cc UJ Q Q LU CC 1-co o UJ z o H LU CO co UJ I-cc m X 15 15 I 50/4"(SPTt 20 -+-20 25 25 P 88/10" (Ring) SP SM SM SAND: Olive yeilcM/with brownish yellGw,damp,fine to medium-grained sand.trace siit SILTY SAND: Pale yellow to light gray,mdst,fine to coarse-grained sand.trace clay and gravel SILPT SAND: Pale yellow,mdst,fine to medium-grained sand.trace clay 9.9 114.6 12.4 /A FIELD LOG OF BORING B - 4 Sheet 1 of 2 /A Project: New Residential Devopment (5 Lots)-Carlsbad SOILS ENGINEERING, INC. Location: 625 Tamarack Avenue Project No. 01-5421 Dates(s) Drilled: Drilled By: Rig Make/Model: Drilling Method: Hole Diameter: 11/26/01 C&C Drilling Company Mobile B-61 Hollow-stem Auger 8 In. Logged By: Gary Martin Total Depth: 40 Feet Hammer Type: Wireline downhole Hammer Weight/Drop: 140 Lb./±30 In. Surface Elevation: Unknown Comments: Groundwater encountered at 34.0'. LL X H Q. UJ D Z o i UJ _I UJ CO SAMPLE INTERVALS UJ b P- a /^ B > CD O _i o CO X o H CO _1 D GEOTECHNICAL DESCRIPTION o Q. CO >- z cc m Q Q UJ H IH Q o z o H UJ CO h-co UJ H CC in X 5 -^-5 10 — 10 15 15 65/10" (Ring) 50/6"(Ring; 50/6"(Ring; 36(SPT) 36(Rlng) SM SM SM SM SM SP-SM I - -7 -1 SP 25/6"(SPT) [JZ -i 30/6"(SPT)-r;^ ML SILTY SAND: Dari< brown.mdst to very mdst.fine-grained sand SILTY SAND: Dark yellowish brown,moist,fine-grained sand SILTiC SAND: Yellowish brown to brown.mdst to damp,fine to medium- grained sand,trace clay same as at)ove.becoming light olive brown SILTY SAND: Ught dive brown.damp to mdst,fine-grained sand same as above SAND: Ught divebrown.mdst.fineto medium-grained sand.trace silt i SAND WITH GRAVEL Pale I yellow.damp.fine to medium-grained sand SANDY SILT WITH CLAY: Pale olive,mdst.fine-grained sand 121.5 121.2 104.0 111.7 8.7 7.0 5.7 5.4 8.1 100.1 7.3 3.6 15.6 CONSOL SHEAR SOILS ENGINEERING, INC. FIELD LOG OF BORING B - 4 Sheet 2 of 2 Project: New Residential Devopment (5 Lots)-Carlsbad Location: 625 Tamarack Avenue Project No. 01-5421 LL X H Q. UJ D Z o < CO _i m SAMPLE INTERVALS m CL o m /•- - > CD O _i O X CO o CO 3 GEOTECHNICAL DESCRIPTION o Q. CO >- z cc in Q Q UJ cc 3 I-co o UJ H z o o z o h- UJ di CO H CO UJ H oc LU X 20 20 25 25 30 30 35 35 40 40 • 50/6"(Ring; 82(SPT) SM SM SM I 82/9"(Ring: 74(SPT) SM I 82/9"(SPT; SM SM SILTY SAND WITH GRAVEL Pale dive,mdst,fine-grained sand and gravel S\LTY SAND WITH CLAY: Ught gray to yellow.mdst.fine to mediun>-grained sand SILTY SAND: Ughtgray.mdst.fineto medium-grained sand.trace clay 81.7 109.0 same as above.becoming pale yellow SILTY SAND WITH CLAY: Pale yellow.very mdst to mdst.fine to coarse-grained sand 116.5 same as above 11.5 15.1 11.7 14.3 17.0 12.4 APPENDIX B LABORATORY TESTS After samples were visually classified in the laboratory, a testing program that would provide sufficient data for our evaluation was established. MOISTURE CONTENT AND DENSITY TESTS The undisturbed soil retained within the sampler rings was tested in the laboratory to determine in-place dry density and moisture content. Test results are presented on the Logs of Borings. CONSOLIDATION AND DIRECT SHEAR TESTS Consolidation and direct shear tests were performed on selected relatively undisturbed and remolded samples to determine the settlement characteristics and shear strength parameters of various soil samples, respectively. The results of these tests are shown graphically on the appended "C" and "D" Plates. MAXIMUM DENSITY TEST The following maximum density test was conducted in accordance with ASTM Dl 557-91, Method A, using 5 equal layers, 25 blows each layer, 10-pound hammer, 18 inch drop in a 1/30 cubic foot mold. The results are as follows: BORING NO. DEPTH, FEET MAXIMUM DRY DENSITY, PCF OPTIMUM MOISTURE CONTENT. % MATERIAL CLASSIFICATION B-1 0-5 131.5 8.5 SM Manning Homes 01-5421 December 13, 2001 Page 21 SOILS ENGINEERING. INC. APPENDIX B - continued EXPANSION TEST An expansion test was performed on a soil sample to determine the swell characteristics. The expansion test was conducted in accordance with a modification of the Uniform Building Code Standard No. 18-2, Expansion Index Test. The expansion sample was remolded to approximately 90 percent relative compaction at near optimum moisture content, subjected to 144 pounds per square foot surcharge load and saturated. LOCATION MAX. DRY DENSITY, PCF OPT. MOIST. CONTENT. % MOLDED DRY DENSITY. PCF MOLDED MOISTURE CONTENT. % % SATURATION EXPANSION INDEX EXPANSION CLASSIFICATION Boring B-1 @ 0-5' 131.5 8.5 119.8 7.8 51.6 0 Very Low SOIL SULFATE Laboratory testing was performed per guidelines of California 417-A test procedures on a representative sample of on-site soils. The test is intended to provide data for a preliminary assessment relative to the potential for concrete deterioration due to soil sulfate. The test result is shown below: SAMPLE SULFATE CONTENT (% BY WEIGHT OF DRY SOIL) Boring B-1 @0- 5' 0.004 Manning Homes 01-5421 December 13, 2001 Page 22 SOILS ENGINEERING. INC. 0.00 1.00 2.00 3.00 4.00 -7^ 5.00 c .o CO 6.00 o ^ 7.00 8.00 9.00 10.00 11.00 12.00 i 1 / nduD Wi th' Wi itor Taj " 1 1 I 1 1 j ! 1 1 I i 1 ! ] 1 i i i 1 ! . 1 i i -i i 1 - 1 1 1 III ' : t 1 ' ! I i i 1 1 1 I 1 j 1 1 1 0.1 1.0 10.0 Pressure ,p (ksf) 100.0 Boring No. B-2 Depth (ft.) 9.0 Sample Undisturbed Sample Type : Silty Fine Sand Dry Density (pcf) = 108.2 Moisture (%) = 6.4 Project Name:5 Residences-625 Tamarack Ave.-Carlsbad Project No.: 01-5421 ASSOCIATED SOILS ENGINEERING, INC. ONE-DIMENSIONAL CONSOLIDATION PROPERTIES OF SOILS (ASTM D 2435) PLATE C-1 0.00 1.00 2.00 3.00 4.00 ^ 5.00 c o ro 6.00 <=> 7.00 8.00 9.00 10.00 11.00 12.00 —1 A 1 1 / ( Indue datf w th "To •1 IA/ —l-a J VV 1 H > -i 1 i 1 i j 1 1 ; 1 1 i 1 1 i 1 1 1 —1— ! i—'— i ! 1 1 1 1 1 ; i : 1 I I 1 1 i [ : i 1 1 1 1 \ I 1 i ! 1 i ' i -1 I - 1 i ! i ; i 1 : 0.1 Boring No. Depth (ft.) Sample 1.0 10.0 Pressure ,p (ksf) 100.0 B-3 13.0 Undisturbed Dry Density (pcf) = 109.9 Moisture (%) =3.6 Sample Type : Fine to Medium Sand with trace Silt Project Name:5 Residences-625 Tamarack Ave.-Carlsbad Project No.: 01-5421 ASSOCIATED SOILS ENGINEERING, INC. ONE-DIMENSIONAL CONSOLIDATION PROPERTIES OF SOILS (ASTM D 2435) PLATE C c o ra 0.00 1.00 2.00 3.00 4.00 5.00 6.00 o ° 7.00 8.00 9.00 10.00 11.00 12.00 < L- / / -/-ndur w th Ta 1W I 1 i J i \ j i 1 1 1 i I 1 [ 1 1 i \ 0.1 1.0 10.0 Pressure ,p (ksf) 100.0 Boring No. B-4 Depth (ft.) 2.0 Sample Undisturbed Sample Type : Silty Fine Sand Dry Density (pcf) = 121.5 Moisture (%) = 8.7 Project Name:5 Residences-625 Tamarack Ave.-Carlsbad ASSOCIATED SOILS ENGINEERING, INC. Project No.: 01-5421 ONE-DIMENSIONAL CONSOLIDATION PROPERTIES OF SOILS (ASTM D 2435) PLATE C-3 2.0 Nonnal Stress (kip/ft^ Boring No. : B-2 Depth(ft.) : 2.0 Sample : Undisturbed Moisture : Saturated Sample Type : Silty Fine Sand Cohesion(C) = 90 psf Friction (([») = 26° Dry Density (pcf) = 105.7 Moisture (%) = 3.4 Project Name:5 Residences-625 Tamarack Ave.-Carlsbad Project No.: 01-5421 ASSOCIATED SOILS ENGINEERING, INC. DIRECT SHEAR TEST RESULTS (ASTM D 3080) PLATE D-1 Q Q I I I I I I I I I I I I I I I I I I I I I I 1 1 1 1 1 1 1 1 1 1 1 ! 1 1 1 1 1 1- 0.0 1.0 2.0 3.0 4.0 Normal Stress (kip/ft^ Boring No. : B-4 Cohesion(C) = 100 psf Depth(ft.) : 4.0 Friction ((j)) =31° Sample : Undisturbed Dry Density (pcf) = 121.2 Moisture : Saturated Moisture (%) =7.0 Sample Type : Silty Fine to Medium Sand with trace Clay Project Name:5 Residences-625 Tamarack Ave.-Carlsbad Project No.: 01-5421 ASSOCIATED SOILS ENGINEERING, INC. DIRECT SHEAR TEST RESULTS (ASTM D 3080) PLATE D-2 Boring No. : B-1 Depth (ft.) : 0-5 Sample : Remolded(90% of Maximum Density) Moisture : Saturated Sample Type : Silty Fine Sand with trace Clay Cohesion(C) = 125 psf Friction ((j)) =32.5° Dry Density (pcf) = 118.4 Moisture (%) = 8.5 Project Name:5 Residences-625 Tamarack Ave.-Carlsbad Project No.: 01-5421 ASSOCIATED SOILS ENGINEERING, INC. DIRECT SHEAR TEST RESULTS (ASTM D 3080) PLATE D-3