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PROPOSAL FOR REMEDIATION SERVICES <br /> �., MOBIL SERVICE STATION X10-NP4 <br /> Am TRACY, CALIFORNIA <br /> One soil sample from the boring near the former waste oil <br /> tank will be analyzed for Priority Pollutant metals (EPA <br /> Method 3550 and 6010) ; and semivolatile organic compounds <br /> (EPA Method 8270) . <br /> o Evaluation of soil permeability. These data are needed <br /> to evaluate well spacings and well yields and trench <br /> dimensions for a groundwater extraction and treatment <br /> system. <br /> We will conduct rising head permeability (slug) tests in <br /> each of the site monitoring wells to assess aquifer <br /> hydraulic conductivity; <br /> o Assessment of soil infiltration capacity. These data <br /> are needed to assess the potential performance of soil <br /> flushing systems. <br /> We propose to conduct up to three percolation tests in <br /> vadose zone soils. If possible, these tests will be <br /> conducted in excavations associated with soil removal <br /> near the underground gasoline tank area and/or pump <br /> islands; and <br /> o Evaluation of the downgradient extent of groundwater <br /> contamination. These data will be used to size and <br /> locate groundwater treatment facilities such as recovery <br /> wells and water treatment equipment. <br /> We will collect groundwater samples from each of the site <br /> monitoring wells. Eight groundwater samples, a quality <br /> control duplicate sample, and a field blank will be <br /> submitted to a DHS certified laboratory for chemical <br /> analysis. The samples will be collected after purging at <br /> least three casing volumes from each well . Purge water <br /> will be contained on-site for appropriate disposal. The <br /> groundwater samples will be collected in appropriate <br /> containers, placed in ice chests, and promptly delivered <br /> to the laboratory for analysis. Groundwater samples will <br /> be analyzed for TPH (Modified EPA Method 8015) and BTEX <br /> (EPA Method 602) . <br /> The groundwater sample collected from well MW-3 will also <br /> be analyzed for semivolatile organic compounds using EPA <br /> Method 625. <br /> The thickness of floating hydrocarbon accumulations in <br /> the wells, if present, will be assessed using a <br /> hydrocarbon interface probe prior to sampling. Field <br /> parameters including pH, temperature. specific <br /> -5- <br />