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Home My WebLink AboutTract Map 9833-3 Lot 5 Limited Geotechnical Study I~ I .......'='''.'1. EN Corporation . Soil Engineering and Consulting Services . Engineering Geology-CompaclionTesting -Inspections. ConstruclionMalerialsTesting elaboratolYTesling .Perco\alionleslinll eGeology-WaterResourceSludies . Phase I & It Environmenlal SileAssessments ENVIRONMENTAL & GEOTECHNICAL ENGINEERING NETWORK I I I I I LIMITED GEOTECHNICAL STUDY Proposed Single Family Residence, Lot 5 of Tract 9833-3 Calle De Velardo, City of Temecula, County of Riverside, California Project Number: T1669-LGS April 8, 1999 I I I I I I I I I Prepared for: Mr. David Ashby 24795 Shoshonee Drive ',\Murrieta, California 92562 '/ " / ~ , " \ - - - \" /,' - / - - I '. , , ' , . ;,CC;.-,;,,;;.i::;,.., II "I I I I I I I I I I I I I I I I I I Mr. David Ashby Project No: T1669-LGS TABLE OF CONTENTS Section Number and Title Paae 1.0 SITE DESCRIPTION ....................................................................................................... 1 1.1 Location ...............................................................................................................1 1.2 Site Review .......................................................................................................... 1 2.0 EARTHWORK RECOMMENDATIONS ..........................................................................1 2.1 General................................................................................................................ 1 2.2 Structural Fill........................................................................................................ 2 3.0 FOUNDATION DESIGN RECOMMENDATIONS ........................................................... 3 3.1 General ............................................................................................................... 3 4.0 RECOMMENDATIONS ................................................................................................... 3 4.1 Utility Trench ........................................................................................................3 4.2 Finish Lot Drainage Recommendations............................................................... 3 4.3 Planter Recommendations...................................................................................4 4.4 Supplemental Construction Observations and Testing ........................................4 4.5 Plan Review .........................................................................................................4 4.6 Pre-Bid Conference ............................................................................................. 4 4.7 Pre-Grading Conference......................................................................................5 5.0 CLOSURE............................. ............... ............................................. ............................ 5 2.. EnGEN Corporation I~ I ..i. qUill" ':,..' . ',. . EN I I I I I I I I I I I I I I Corporation . Soil Engineering and Consulting Services-Engineering Geology. GompactionTesting e Inspections eConstructionMaterialsTesling.laboraloryTesling.Perc olationTesting _Goology_WaterResourceSludies _ Phasel& II En'lironmentalSileAssessments ENVIRONMENTAL & GEOTECHNICAL ENGINEERING NETWORK April 8, 1999 Mr. David Ashby 24795 Shoshonee Drive Murrieta, California 92562 (909) 696-9148 IFAX (909) 696-3938 Regarding: LIMITED GEOTECHNICAL STUDY Proposed Single Family Residence, Lot 5 of Tract 9833-3 Calle De Velardo, City of Temecula, County of Riverside, California Project Number: T1669-LGS Reference: 1. Lawrence O. McDermott, Grading Plan, Ashby Residence, plans undated. Dear Mr. Ashby: Per your request and signed authorization, a representative of this firm has visited the subject site on April 6, 1999, to visually observe the surface within the subject lot. 1.0 SITE I PROJECT DESCRIPTION 1.1 Location I Proiect Description: The subject property is comprised of approximately two (2) acres located near the terminus of Calle De Velardo in the City of Temecula. The proposed development is a one or two story slab-on-grade residential structure. The remainder of the site will consist of a driveway and associated hardscape and landscape improvements. 1.2 Site Review: Based on the site visit and literature research, it appears that Pauba Formation bedrock and shallow depths of alluvium underlie the site and surrounding area. Based on the density of the underlying earth material type (Pauba Formation) the potential for hazards associated with liquefaction is considered low. No active faults traverse the site. Based on favorable topography, the potential for hazards associated with rockfalls or landslides is considered low. No unusual geological conditions were noted. -..\ , , / , , ' / " ~ ~ - , " \ - - ~ \" , " / " ~ I",. I " - /",,-- /",~-- /"'~--' " J , ~ \ _ _ _ \ ..- " "' , "' \ _ _ _ \,," ~ I -" ,_ _ _ \ ..- .... ~ I -" , ~~":%~"~~'~~~'~4i~~~~~~~i~~~~~~~iiiii~i: X__=B.~~lli~M_ft~._U_~8~__~_~_.~~~~~_~@.g., '.~ --. ".' ~.._". "'~'9-':-- ,--.-"'-------..----- =:;::: '/ " ,~ "", \- -- \ , ,,~ ,"- , , . , ," ~ - - I . , ~ -- ! I '. '. I I I I I I I I I I I I' I I I I I 2.0 2.1 Mr. David Ashby Project No: T1669-LGS April 1999 Page 2 EARTHWORK RECOMMENDATIONS General . All vegetation should be removed from areas to be graded and not used in fills. . A cut/fill transition traverses the proposed residential structure and garage area. Therefore the cut portion (and shallow fill portion) will need to be overexcavated so that all footings will be embedded into competent engineered fill. The depth of overexcavation is expected to be a minimum of four (4) feet below proposed finish grades and may be deeper depending on exposed conditions encountered during grading. Overexcavation should extend a minimum of five (5) feet beyond the perimeter footings. . All areas to receive fill will require removals of loose, incompetent slopewash and/or alluvial materials. Depths of removals are expected to be two (2) to three (3) feet below existing grades but may be deeper depending on exposed conditions encountered. . All removal and overexcavation bottoms should be inspected by the Soil Engineer's representative prior to placing fill. After bottom approval, all bottoms should be scarified 12-inches, moisture conditioned to near optimum moisture and then recompacted to a minimum of 90 percent relative compaction. . A keyway excavated into competent native earth materials should be constructed at the toe of all proposed fill slopes that are proposed on natural grades of 5: 1 (horizontal to vertical) or steeper. Keyways should be a minimum of 15 feet wide (equipment width) and tilted a minimum of 2 percent into the hillside. A series of level benches should be constructed into native competent earth materials on natural grades of 5: 1 (horizontal to vertical) or steeper prior to placing fill. . All proposed cut and fill slopes should be constructed at a slope ratio no steeper than 2:1 (horizontal to vertical). . All cut slopes should be inspected during (or immediately after) grading to verify stability. . An expansion test should be performed on a representative soil sample retrieved from the finished pad area subgrade so that foundation recommendations can be verified. L\ EnGEN Corporation I ,. I . . I I I I . I I I I . I . I I Mr. David Ashby Project No; T1669-LGS April 1999 Page 3 2.2 Structural Fill: All fill material, whether on-site material or import, should be approved by the Project Geotechnical Engineer and/or his representative before placement. All fill should be free from vegetation, organic material, and other debris. Import fill should be no more expansive than the existing on-site material. Approved fill material should be placed in horizontal lifts not exceeding 6.0 to 8.0-inches in thickness and watered or aerated to obtain near-optimum moisture content (2.0 percent of optimum). Each lift should be spread evenly and should be thoroughly mixed to ensure uniformity of soil moisture. Structural fill should meet a minimum relative compaction of 90 percent of maximum dry density based upon ASTM D1557-78 (90) procedures. Moisture content of fill materials should not vary more than 2.0 percent of optimum, unless approved by the Project Geotechnical Engineer. 3,0 FOUNDATION DESIGN RECOMMENDATIONS 3.1 General: Foundations for the proposed structure may consist of conventional column footings and continuous wall footings founded in competent engineered fill. Minimum footing depth should be 12-inches below lowest adjacent grade. Recommendations for foundation design and construction should be provided by the Structural Engineer in accordance with the latest edition of the use and should be based on geotechnical characteristics for a silty sand (SM) and a low expansion potential for the supporting soils and should not preclude more restrictive structural requirements. 4.0 RECOMMENDATIONS 4.1 Utility Trench Recommendations: Utility trenches within the zone of influence of foundations or under building floor slabs, hardscape, and/or pavement areas should be backfilled with properly compacted soil. It is recommended that all utility trenches excavated to depths of 5.0 feet or deeper be cut back to an inclination not steeper than 1: 1 (horizontal to vertical) or be adequately shored during construction, Where interior or exterior utility trenches are proposed parallel and/or perpendicular to any building footing, the bottom of the trench should not be located below a 1: 1 plane projected downward from the outside bottom edge of the adjacent footing unless the utility lines are designed for the footing surcharge loads. Backfill material should be placed in a lift thickness appropriate for the type of backfill material and compaction equipment used. Backfill material should be compacted to a minimum of 90 percent relative compaction by mechanical means. Jetting of the backfill material will not be considered a satisfactory method for compaction. Maximum dry density EnGEN Corporation I ;)'1 I I . I . I I . I . . I I . I I I 4.2 4.3 4.4 4.5 Mr. David Ashby Project No: T1669-LGS April 1999 Page 4 and optimum moisture content for backfill material should be determined according to ASTM D1557-78(90) procedures. Finish Lot Drainaae Recommendations: Finish lot surface gradients in unpaved areas should be provided next to tops of slopes and buildings to direct surface water away from foundations and slabs and from flowing over the tops of slopes. The surface water should be directed toward suitable drainage facilities. Ponding of surface water should not be allowed next to structures or on pavements. In unpaved areas, a minimum positive gradient of 2.0 percent away from the structures and tops of slopes for a minimum distance of 5.0 feet and a minimum of 1,0 percent pad drainage off the property in a non-erosive manner should be provided. Planter Recommendations: Planters around the perimeter of the structure should be designed with proper surface slope to ensure that adequate drainage is maintained and minimal irrigation water is allowed to percolate into the soils underlying the building. Supplemental Construction Observations and Testina: Any subsequent grading for development of the subject property should be performed under engineering observation and testing performed by EnGEN Corporation. Subsequent 9rading includes, but is not limited to, any additional overexcavation of cut and/or cut/fill transitions, fill placement, and excavation of temporary and permanent cut and fill slopes. In addition, EnGEN Corporation, should observe all foundation excavations. Observations should be made prior to installation of concrete forms and/or reinforcing steel so as to verify and/or modify, if necessary, the conclusions and recommendations in this report. Observations of overexcavation cuts, fill placement, finish grading, utility or other trench backfill, pavement subgrade and base course, retaining wall backfill, slab presaturation, or other earthwork completed for the development of subject property should be performed by EnGEN Corporation If any of the observations and testing to verify site geotechnical conditions are not performed by EnGEN Corporation, liability for the safety and performance of the development is limited to the actual portions of the project observed and/or tested by EnGEN Corporation. Plan Review: Subsequent to formulation of final plans and specifications for the project but before bids for construction are requested, grading and foundation plans for the proposed development should be reviewed by EnGEN Corporation to verify compatibility with site geotechnical conditions and conformance with the recommendations contained in this report. If EnGEN Corporation is not accorded the opportunity to make the recommended review, S" EnGEN Corporation II '\1 I . . I I I I I . . . I I I . I I 4.6 4.7 5.0 Mr. David Ashby Project No: T1669-LGS April 1999 Page 5 we will assume no responsibility for misinterpretation of the recommendations presented in this report. Pre-Bid Conference: It is recommended that a pre-bid conference be held with the owner or an authorized representative, the Project Architect, the Project Civil Engineer, the Project Geotechnical Engineer and the proposed contractors present. This conference will provide continuity in the bidding process and clarify questions relative to the supplemental grading and construction requirements of the project. Pre-Gradinll Conference: Before the start of any grading, a conference should be held with the owner or an authorized representative, the contractor, the Project Architect, the Project Civil Engineer, and the Project Geotechnical Engineer present. The purpose of this meeting should be to clarify questions relating to the intent of the supplemental grading recommendations and to verify that the project specifications comply with the recommendations of this geotechnical engineering report. Any special grading procedures and/or difficulties proposed by the contractor can also be discussed at that time. CLOSURE: This report has been prepared for use by the parties or project named or described in this document. It mayor may not contain sufficient information for other parties or purposes. In the event that changes in the assumed nature, design, or location of the proposed structure and/or project as described in this report, are planned, the conclusions and recommendations contained in this report will not be considered valid unless the changes are reviewed and the conclusions and recommendations of this report modified or verified in writing. This study was conducted in general accordance with the applicable standards of our profession and the accepted soil and foundation engineering principles and practices at the time this report was prepared. No other warranty, implied or expressed beyond the representations of this report, is made. Although every effort has been made to obtain information regarding the geotechnical and subsurface conditions of the site, limitations exist with respect to the knowledge of unknown regional or localized off-site conditions that may have an impact at the site. The recommendations presented in this report are valid as of the date of the report. However, changes in the conditions of a property can occur with the passage of time, whether they are due to natural processes or to the works of man on this and/or adjacent properties. If conditions are observed or information becomes available during the design and construction process that are not reflected in this report, EnGEN Corporation should be notified so that supplemental evaluations can be performed and the EnGEN Corporation <;, I I I ,\,. \- I I I I I I I I I I I I I I . I I I Mr. David Ashby Project No: T1669-LGS April 1999 Page 6 conclusions and recommendations presented in this report can be modified or verified in writing. Changes in applicable or appropriate standards of care or practice occur, whether they result from legislation or the broadening of knowledge and experience. Accordingly, the conclusions and recommendations presented in this report may be invalidated, wholly or in part, by changes outside of the control of EnGEN Corporation which occur in the future. Thank you for the opportunity to provide our services. Often, because of design and construction details which occur on a project, questions arise concerning the geotechnical conditions on the site. If we can be of further service or you should have questions regarding this report, please do not hesitate to contact this office at your convenience. Because of our involvement in the project to date, we would be pleased to discuss engineering testing and observation services that may be applicable on the project. Respectfully submitted, ~Co= Thomas Dewey, CEG 1975 Senior Engineering Geologist Expires 11-30-99 TD/08:aa ~ Distribution: (4) Addressee FILE: EnGEN\ReportingIGSIT1669LGS Mr. David Ashby, Limned Geotechnical Study EnGEN Corporation 1