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_.... 11 <br /> 7-Eleven/Stockton <br /> November 1989 <br /> gallons of water were removed from each well, assuring a fresh <br /> flow of water from the aquifer to the wells. The wells were then <br /> allowed to recover to at least 80 percent of their original <br /> volume before sampling with an EPA-approved Te:'.lonR sampler. <br /> Groundwater samples were stored in 40-milliliter glass VOA vials, <br /> labeled, placed on ice and transported under Chain-of-Custody <br /> Manifest to GTEL, in accordance with GTI SOPS 9, 10, 11 and 12 <br /> (Appendix B) . Laboratory results of groundwater samples are <br /> presented in Appendix C. <br /> SITE SUBSURFACE CONDITIONS <br /> The application of continuous coring during the drilling of <br /> MW--15 and MW-16 has provided for a more-accurate characterization <br /> of the subsurface soil profile at the site. These additional <br /> details have aided the interpretation of the subsurface geology <br /> , and hydrogeology. <br /> Subsurface matr _ .als encountered during the recent drilling <br /> 7:h.P <br /> suggest that the subsurface stratigraphy is composed of two <br /> distinct sequences. A generalized geologic cross-section <br /> � (Figure 3) illustrates the site's subsurface geology. The upper <br /> sequence is marked by a basal gravelly coarse sand, overlain by <br /> fine sands and silts, and capped by a silty clay. The lower <br /> and bodies encased <br /> sequence consists of laterally discontinuous s <br /> within silts and silty clays. <br /> This model aids in the interpretation of the history of <br /> groundwater recovery since the installation of the on-site <br /> recovery well (RW-1) in March, 1988. Following <br /> the <br /> installation <br /> of RW-1, the initial dissolved-hydrocarbon concentrations <br /> recovered were 7,800 ppb TPH-as-gasoline. once <br /> RW-ihad <br /> Glcnt%utikves <br /> 1 Fa Ej�1H�H.1.INC. <br />