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1/n/ADelta <br /> Enui�onmental <br /> Consultants, Inc. WE '"& <br /> 3330 Data Drive <br /> Rancho Cordova, CA 95670 JUN 7 1999 <br /> 916/638-2085 <br /> FAX:916/636-8385 ENVIRONMENTAL HEALTH <br /> PERMIT/SERVICES <br /> June 1, 1990 <br /> Mr. Harlin Knoll <br /> San Joaquin County Local Health District <br /> 1601 East Hazelton Avenue <br /> Stockton, California 95201 <br /> Subject: Soil Remediation, Shell Service Station <br /> 3725 Tracy Boulevard, Tracy, California <br /> Shell WIC No. 204-7884-0901 <br /> Delta Project No. 40-89-012 <br /> Dear Mr. Knoll: <br /> Approximately 400 cubic yards of soil containing petroleum hydrocarbons have been excavated at the <br /> subject site and transported to disposal facilities. The soil has been removed from the former and new <br /> product storage tank locations and from the former pump island locations. Soil located below the <br /> surface to a depth of approximately 9 feet and determined to contain petroleum constituents has been <br /> removed. However, petroleum constituents have been identified in soil at the water table, <br /> approximately 10 feet below the surface. <br /> The enclosed figure displays the soil sampling points where petroleum constituents have been <br /> identified at the water table. Based on these data, it is Delta Environmental Consultants, Inc., opinion <br /> that the soil at the water table beneath much of the northeastern portion of the site contains <br /> petroleum constituents. <br /> Site remediation will take place following acceptance by San Joaquin County of a Preliminary Report, <br /> a Problem Assessment Report, and a Final Remedial Plan. However, to reduce site disruption later <br /> (pavement removal and trenching in the vicinity of future product lines), we will be installing ground <br /> water gradient control pipe and soil vent pipe now. These pipes will become part of a system <br /> incorporating ground water gradient control and soil vapor extraction. This system will be proposed <br /> in detail in a Final Remedial Plan and operated only after County approval of the plan. <br /> The enclosed figures display the pipe locations and configurations. A perforated pipe placed in a <br /> trench at 13 feet below the surface and connected to a sump will later be used to lower the water <br /> table. This will allow remediation of the soil containing petroleum constituents by vapor extraction <br /> through a slotted pipe placed in the same trench at 9 feet. <br /> Practical Solutions to Environmental Concerns <br />