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2.6 Contract Laboratory <br /> Testing done by: Sequoia Analytical Laboratories <br /> 680 Chesapeake Drive <br /> Redwood City, CA 94063 <br /> " DOHS Certification No. 1.45 <br /> i <br /> An authorization to release Data Form signed by the Linden <br /> �. School District is on file with San Joaquin County Public <br /> : r <br /> Health Services. <br /> 3.0 PROPOSED WORKPLAN <br /> r <br /> To mitigate the remaining gasoline contamination in soil <br /> � WaterWork proposes to re-excavate the former tank pit. <br /> The following scope of work is proposed: <br /> 1. Prior to re-excavation a soil sample will be collected <br /> from the bottom of the pit and analyzed for organic <br /> lead and total soluble lead. These tests are necessary <br /> as the laboratory analyzed the original sample for total <br /> lead instead of organic lead. <br /> 2. Re-excavation of the tank pit to a maximum depth of 15 <br /> feet. In the north, east and west directions the <br /> excavation will be continued until visual, field and PID <br /> evidence indicate that the hydrocarbon concentrations <br /> have been substantially reduced. Excavation in the <br /> -- southerly direction is limited by the foundation of the <br /> maintenance building. <br /> 3. Collection of two floor and four wall confirmation <br /> samples with the excavator bucket. One sample will, be <br /> collected from each wall approximately 1 foot above the <br /> floor. The samples will be analyzed by Sequoia <br /> Analytical Laboratory, a State certified laboratory, for <br /> benzene, toluene, ethylbenzene, xylenes (BTEX) and total <br /> petroleum hydrocarbons as gasoline (TPHG) by EPA Methods <br /> M 8015 and 8020. <br /> 4. All excavated soil will be stored on 6 mil plastic and <br /> covered with the same. One composite sample (4 to 1) <br /> will be collected for every 100 cubic yards of soil <br /> removed. The samples will be analyzed for BTEX and <br /> OTPHG. The contaminated soil will be aerated on site <br /> until gasoline concentrations are below 100 parts per <br /> million. The aerated soil w U l then be spread on the <br /> school property. Aeration will be performed under a <br /> permit from the San Joaquin County Air Resources Board. <br /> 5. The excavation will be backfilled with pea gravel and <br /> capped with asphalt. <br /> 2 <br />