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1992 Third Quarter Groundwater Monitoring Report <br /> ort <br /> r.- <br /> Western Stone Products, Tracy, California <br /> �-.rte{ August 28, 1992 <br /> Page 4 <br /> excavation, however excavation will continue until field evidence indicates that all accessible <br /> contaminated soil has been removed. <br /> Upon completion of excavation, 8 sidewall samples will be collected, if possible, to confirm <br /> source removal. Two samples will be collected from each sidewall, at depths of approximately <br /> 5 and 8 feet below grade. The samples will be submitted to a DHS certified laboratory to be <br /> analyzed for benzene, toluene, ethylbenzene, and xylenes (BTEX) and total petroleum <br /> hydrocarbons as diesel (TPHD) by EPA methods 5030/8020/modified 8015. A mobile <br /> laboratory may be used in order to secure immediate analytical results. <br /> Excavated soil will be stockpiled on site, underlain by asphalt or visqueen and covered with <br /> visqueen until sampled and disposed of in an appropriate manner. One 4 container composite <br /> sample will be collected and analyzed for TPHD and BTEX. Upon receipt of the results <br /> RESNA will submit a soil disposal plan. It is expected, based on the results from SBI soil <br /> samples, that we will propose that the material be used as roadbase. <br /> GROUNDWATER SAMPLING <br /> Insofar as excavation activities will in all likelihood introduce contaminants to the groundwater, <br /> we propose to pump at least 2 tank pit volumes from the excavation, allowing recharge between <br /> pumping intervals. Water will be stored in a Baker tank, and sampled for BTEX and TPHD to <br /> establish baseline concentrations. A groundwater sample will also be collected from the tank <br /> pit and analyzed for TPHD/BTEX to confirm removal of impacted water. Following the <br /> collection of samples, the excavation will be backfilled, upon the recommendation of San <br /> Joaquin County Community Development Department, with self-compacting clean sand. <br /> The water in the Baker tank will be remediated, if needed, by natural or enhanced <br /> bioremediation. The stored water will be periodically sampled and analyzed for TPHD and <br /> BTEX to gauge the progress of remediation. If samples confirm that the water is clean, San <br /> Joaquin County PHS/EHD will be notified requesting permission to discharge directly to the <br /> surface or to the facility septic system. <br /> All activities involving potential exposure to contaminants (TPHD/BTEX) will be conducted in <br /> accordance with the site Health and Safety Plan (Attachment 4). All site activities will be <br /> conducted under the supervision of a properly registered professional. <br /> QR081292.DRF <br />