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PERIODIC GROUNDWATER EXTRACTION <br /> Cambria proposes to remove approximately 5,000 gallons (the capacity of one vacuum truck) on a <br /> regular weekly basis for a period of approximately six months The ground water will be removed <br /> from well RW-1 in the location of the former tank complex The removal rate of one 5,000-gallon <br /> vacuum truck each week is approximately the same as pumping at a continuous pumping rate of 0 5 <br /> gallons per minute The extracted ground water will be transported by truck to the Shell refinery in <br /> Martinez, California for treatment and disposal <br /> INSTALLATION OF OXYGEN RELEASING COMPOUNDS (ORCs) <br /> Cambria proposes to install oxygen releasing compounds in onsite monitoring wells near the <br /> perimeter of the site to augment the natural attenuation by increasing the oxygen supply in the <br /> subsurface Placing ORCs in perimeter wells combined with GWE in the source area should move <br /> oxygenated ground water toward and through the hydrocarbon source zone ORC `socks' will be <br /> installed in wells MW-2, MW-8, MW-3, and MW-4 Dissolved oxygen concentrations will be <br /> monitored to evaluate when ORC materials should be replaced with new ORCs To avoid removal of <br /> oxygenated ground water, sampling of wells containing ORCs will be performed via grab sampling and <br /> without purging <br /> GROUNDWATER MONITORING PROGRAM <br /> Cambria proposes to monitor the extracted ground water for TPPH, BTEX, and MTBE and analyze <br /> ground water from extraction well RW-1 and onsite monitoring wells for intrinsic bioremediation and <br /> RBCA parameters, and continue the quarterly ground water monitoring plan for hydrocarbons <br /> Ground Water Monitoring for Hydrocarbons <br /> To assess the impact of the remedial activities on ground water in the source area, Cambria proposes <br /> to monitor the ground water extracted from RW-1 for TPPH, BTEX, and MTBE, as well as <br /> continuing the existing quarterly ground water monitoring program for remainder of the wells The <br /> extracted ground water will be sampled and analyzed weekly for the first two weeks, then biweekly for <br /> the next month, and monthly thereafter <br /> Intrinsic Bioremediation Parameters <br /> To assess the potential for intrinsic bioremediation to be occurring beneath the site, Cambria <br /> proposes to monitor intrinsic bioremediation parameters in ground water Ground water samples will <br /> be collected from each of the existing onsite monitoring wells during the next quarterly ground water <br /> monitoring event and analyzed for dissolved oxygen (DO), oxidation/reduction potential (ORP or <br /> • Eh), pH, conductivity and temperature in the field Ground water samples will also be analyzed for <br /> 240-0783 26 <br />