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Home My WebLink About; Single Family Residence Lot 119, Map No. 3312; Rough Grading Report; 2004-12-23COAST GEOTECHNICAL CONSULTING ENGINEERS AND GEOLOGISTS December 23,2004 Laveme and Elaine Brown 5411 Los Robles Drive Carlsbad, CA 92008 Subject: ROUGH GRADING REPORT Proposed Single Family Residence Lot 119, Map No. 3312 Vacant Lot, Carlsbad Boulevard APN 210-115-24 Carlsbad, Califomia Reference: PRELIMINARY GEOTECHNICAL INVESTIGATION Proposed Single Family Residence Lot 119, Map No. 3312 Vacant Lot, Carlsbad Boulevard APN 210-115-24 Carlsbad, Califomia Prepared by Coast Geotechnical Dated April 15,2002 Dear Mr. and Mrs. Brown: In response to your request, we have performed field observations and testing during the rough grading phase on the above referenced property. The results of our density tests and laboratory testing are presented in this report. Based on the results of our testing, it is our opinion that the fill was placed in an adequate manner and compacted to a minimum of 90 percent of the laboratory maximum dry density. The control of drainage from lot development is essential to the future performance ofthe stmcture. Ifyou have any questions, please do not hesitate to contact us at (858) 755-8622. This opportunity to be of service is greatly. Respectfully submit^^y^^ COAST GEOTECWOT?^ C\? 2109 ^\(r' Exp. 5-31-06 CERTIFIED ENGINEERING /.r: • '' • Mark Burwell, C.] Engineering Geologi Vithaya Singh Geotechnical En 779 ACADEMY DRIVE • SOLANA BEACH. CALIFORNIA 92075 (858) 755-8622 • FAX (858) 755-9126 ROUGH GRADING REPORT Proposed Single Family Residence Lot 119, Map No. 3312 Vacant Lot, Carlsbad Boulevard APN 210-115-24 Carlsbad, California Prepared for: Laverne and Elaine Brown 5411 Los Robles Drive Carlsbad, CA 92008 December 23, 2004 W.O. G-357032 Prepared by: COAST GEOTECHNICAL 779 Academy Drive Solana Beach, California 92075 Coast Geotechnical December 23, 2004 W.O. G-357032 Page 3 INTRODUCTION This report presents the results of our observations and field density testing on the subject property during rough grading. The project included the removal and recompaction of soil and weathered terrace deposits in the rear ofthe building envelope and the excavation of a partial basement in the westem portion of the site. The approximate locafions of field density tests are shown on the enclosed Grading Plan, prepared by KRH Engineering. LABORATORY TEST DATA The laboratory standard for determining the maximum dry density was performed in accordance with ASTM D 1557-91. Field density tests were performed in accordance with ASTM D 1556. The results ofthe laboratory maximum dry density, for the soil type used as compacted fill on the site, is summarized below: Maximum Dry Density Optimum Description (p.c.f) Moisture (%) Soil Type Tan to brown fine and 128.6 10.1 A medium-grained sand Brown silty, fine and 123.0 11.0 B medium-grained sand GEOTECHNICAL CONDITIONS The property is underlain at shallow depths by Pleistocene terrace deposits. The terrace deposits are Coast Geotechnical December 23, 2004 W.O. G-357032 Page 4 underlain at depth by Eocene-age sedimentary rocks which have commonly been designated as Santiago Formafion on published geologic maps. The terrace deposits are covered by residual soil and minor fill deposits. DISCUSSION The grading contractor on this project was Sorrento Valley Construcfion. The following is a discussion of the general grading operations as they were performed on the project. 1) All surface deleterious material was removed in the building envelope, prior to removals. 2) The soil and weathered terrace deposits in the eastem portion of the residenfial building pad were removed to a depth of approximately 4.0 to 4.5 feet below grade and stockpiled. 3) Stockpiled soils were generally mixed and placed in loose hfts of approximately 8.0 inches, moistened to about optimum moisture content and compacted. Compaction was accomplished by wheel rolling with a Caterpillar mbber fire loader. 4) The eastem portion of the residenfial pad was overexcavated to a maximum depth of approximately 4.5 feet and extended approximately 5.0 lateral feet beyond the building envelope. The overexcavation was limited to approximately 3.0 lateral feet along the northem building line, due to a property line wall. Coast Geotechnical December 23, 2004 W.O. G-357032 Page 5 5) Based on our experience and laboratory testing, the fill deposits have a potenfial expansion in the low range. CONCLUSIONS AND RECOMMENDATIONS 1) Based on selecfive testing, the fill was placed to a minimum of 90 percent ofthe laboratory maximum dry density as suggested by our test results. 2) The soil parameters recommended in the referenced Preliminary Geotechnical Investigation for foundations and slab design remain valid. 3) The following pavement section is recommended for the proposed driveway: 4.0 inches of asphaltic paving or 5.0 inches concrete on 4.0 inches of select base (Class 2) on 12 inches of compacted subgrade soils Subgrade soils should be compacted to the thickness indicated in the stmctural section and left in a condition to receive base materials. Class 2 base materials should have a minimum R-value of 78 and a minimum sand equivalent of 30. Subgrade soils and base materials should be compacted to a minimum of 95 percent of their laboratory maximum dry density. The pavement section should be protected from water sources. Migration of water into subgrade deposits and base materials could result in pavement failure. Coast Geotechnical December 23, 2004 W.O. G-357032 Page 6 4) We recommend that all ufilities be bedded in clean sand to at least one foot above the top of the conduit. The bedding should be flooded in place to fill all the voids around the conduit. Imported or on-site granular material compacted to at least 90 percent relative compacfion may be ufilized for backfill above the bedding. The invert of subsurface ufihty excavafions paralleling footings should be located above the zone of influence of these adj acent footings. This zone of influence is defined as the area below a 45 degree plane projected down from the nearest bottom edge of an adjacent footing. This can be accomplished by either deepening the footing, raising the invert elevafion ofthe ufility, or moving the utility or the foofing away from one another. 5) Positive site drainage should be maintained at all fimes. Water should be directed away from foundations and not allowed to pond or seep into the ground or migrate under concrete flatwork or pavement sections. 6) All the recommendations in the referenced Preliminary Geotechnical Investigation which are not superseded by this report remain valid and should be implemented during the constmction phase. Placement of addifional fill and wall backfill should be observed and tested by a representative ofthis firm. LIMITATIONS This office assumes no responsibility for any alterafions made without our knowledge and written Coast Geotechnical December 23, 2004 W.O. G-357032 Page 7 approval, subsequent to the issuance of this report. All areas of disturbance which require the placement of compacted fill to restore them to the original condition, will not be reviewed unless such backfilling operations are performed under our observation and tested for required compaction. It should be noted that density (compaction) testing is conducted on a very small volume ofthe fill. The intent is to provide an opinion, based on selective testing and observation during fill placement. This study has been provided solely for the benefit of the client and is in no way intended to benefit or extend any right or interest to any third party. This study is not to be used on other projects or extensions to this project except by agreement in writing with Coast Geotechnical. Enclosures: Table I Grading Plan FIELD AND LABORATORY TEST RESULTS Date Test No. TABLE I Field Dry Density and Moisture Content Moisture Dry Relative Test Approx. Content Density % Soil Location Elev. % (pcf) Compaction Type 12/07/04 1 12/09/04 2 12/09/04 3 12/10/04 4 12/10/04 5 See Map See Map See Map 52 . 0 ' 53 . 0 ' 54 . 0 ' See Map S.G. See Map S.G. 11. 7 10 . 9 9.9 10 . 3 10 .1 123 . 6 115 . 6 120.5 118 . 9 116.0 96 90 94 96 94 A A A B B G-357032