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FILE COPY <br /> i <br /> page 2 <br /> 3780 Linne Road <br /> I <br /> 1 <br /> The work plan also proposes that following the geoprobe work they will "discuss the <br /> need for further investigation to determine if the gasoline has migrated through the clay <br /> layer that appears to be present across the site below the depth of approximately 16- <br /> feet". The review of the boring logs from previous work at this site does not support this <br /> f statement. Only one boring, MW-4, was logged as having a clay lens below this depth. <br /> All other borings were logged as clayey-silt below 164eet bsg. The investigation of the <br /> vertical extent of the contamination in the source area must be completed first. <br /> Following that it will be possible to determine the depths to which the lateral borings <br /> must be advanced. <br /> The work plan as submitted is not approved. Please proceed with the preparation of a <br /> new work plan that will address both vertical and lateral definition of the contaminant <br /> plumes at this site. Submit the work plan to PHS/EHD by May 31, 2000. The work <br /> plan must include a boring to depth in the source area to define the vertical extent of the <br /> contamination. At least one boring is needed directly,between the source area and ithe <br /> on-site domestic well. At least one well should be installed between the source area and <br /> the on-site domestic well. Depth discrete sampling of both the soil and groundwater will <br /> be required. Lateral definition of the shallow and, if present,.deep groundwater <br /> contamination will be required. If groundwater contamination is discovered below the <br /> current well screens, deep discretely screened wells will be required. Protection of the <br /> on-site domestic well is of major concern at this site. Please include in the work plan a 1 <br /> description of this well, including the well log if available. As part of your investigation <br /> you are required to conduct a complete well survey of the area, providing the locations of <br /> all domestic, agricultural, industrial, municipal and other wells located within a 2000-foot <br /> radius of the contaminant source. Logs of the wells, if available, should be included in <br /> the survey. The results of the well survey are to be provided to PHSIEHD as soon as <br /> possible and no later than with the report of findings following the next phase of work. <br /> If you have any questions or comments please call Lori Duncan at (209) 468-0337. <br /> Donna Heran, REHS, Director <br /> Environmental Health Division <br /> CA <br /> Lori Duncan, Senior REHS Margare agorio, REH <br /> LOP/Site Mitigation Unit IV Supervisor Unit IV <br /> cc: Marty Hartzell, CVRWQCB <br /> Ray Kablanow, GTI <br /> I <br />