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rc�C�11��il <br /> J J L 1 4 1993 <br /> k" KLEINFELDER �tlyu tj <br /> File No. 20-Y93-067 <br /> July 13, 1993 <br /> Mr. Larry Philips <br /> Brown and Caldwell, Consultants <br /> 723 S Street <br /> Sacramento, CA 95814.7092 <br /> Subject: RECOMMENDED BACKFILL PROCEDURE <br /> KENT'S OIL SERVICE <br /> STOCKTON, CALIFORNIA <br /> Dear Mr. Phillips: <br /> This letter is to document our several discussions regarding the backfilling of a deep excavation <br /> Located in the, iouthern portion of the Kent's Oil facility located on Miner Street in Stockton, <br /> California. Due to property line constraints, we understand that near vertical slopes are desired, <br /> w.. possibly extending to the 40-foot depth, As discussed with you, our firm has been involved in <br /> a number of deep excavations for the purpose of removing contaminated Soil beneath <br /> underground storage tanks. Recently, our firm was involved in the backfill of two 35- to 40-foot <br /> deep excavations at the corners of Pershing Avenue and Robinhood Drive, and Pacific Averme <br /> and Robinnood Drive. Vertical excavations 20 feet deep were also made at our office located <br /> just south of the site on Myrtle Avenue. In all these deep excavations very stiff to hard silt and <br /> clay soils were encountered which is typical for this area. During our site visit we observed <br /> similar soils. For this reason, it is our opinion that the proposed excavation can be made as <br /> planned. <br /> We understand that a large backhoe would be used and will operate on a bench within the <br /> excavation area. We recommend that periodic visits by a staff engineer or geologist from our <br /> firm be made, say every 5 to 10 feet of the remaining excavation, to observe the exposed soils <br /> conditions. However, in our absence, should equipment operators notice any silty or clean Band <br /> layers, they should contact our office immediately so that we may review the conditions and <br /> evaluate possible impacts to the slope configuration. <br /> ,., Once the excavation is complete, rather than mechanically compacting the backfill in the lover <br /> portions of the excavation, we recommend that crushed rock be placed up to the approximate <br /> 15-foot level or at which depth heavy compacting equipment can effectively operate. The gravel <br /> 4 or crushed rock should be vibrated by heavy equipment such as a large vibrating steel drum <br /> roller. In order to return this site to condition similar to the adjacent very stiff soils we <br /> recommend that all native backfill material's be compacted to at least 95 percent of the maximum <br /> dry density as determined by the ASTM D-1557 test procedure. <br /> Ccpyricz; 1593 Kiainfe,der, Inc. <br /> KLEINFELDER 2825 East Myrtle Street, Stockton, CA 95205 (209) 948-1345 <br />