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page 2 <br /> 1817 Fresno Ave. <br /> PHS/EHD does not approve the borings proposed to be located on the north and west <br /> boundaries of the subject property. Documented contamination from the bottom of the <br /> former tank pit, 5, 700 parts per million (ppm) total petroleum hydrocarbon as gas <br /> (TPHg) , is evidence that there was an on-site source of the current groundwater <br /> contamination. Without substantiation of what the potential off-site sources may be to <br /> the west and the north it seems unnecessary to be expending time and energy <br /> investigating these areas, especially to such a shallow level . <br /> PHS/EHD is concerned that investigation of the vertical extent of the groundwater plume <br /> was not included in this work plan . According to California Code of Regulations , Title <br /> 23, Division 3, Chapter 16, section 2725 , the vertical and lateral extent of the release <br /> must be determined prior to developing a cost-effective Corrective Action Plan . Depth <br /> discrete sampling of the groundwater must be performed to enable evaluation of the <br /> vertical extent of the dissolved contaminant plume . It is already known that additional <br /> shallow-screened wells are necessary down-gradient of the existing wells for lateral <br /> definition . It may also be necessary to install on-site deep , discretely screened wells . <br /> Quarterly monitoring of all on-site wells should continue as proposed in the work plan . <br /> As stated previously , the work plan proposes to replace damaged MW-5 by overdrilling <br /> and reinstallation of a new well casing in the same boring . PHS/EHD recommends the <br /> damaged well be properly destroyed by overdrilling and grouting with neat cement and <br /> that a new well is constructed nearby. <br /> The work plan is conditionally approved as outlined above . Please submit a well permit <br /> application signed by the C-57 licensed contractor who will be performing the work along <br /> with the required $89 . 00 permit fee. Please note that 48 hours notice to PHS/EHD is <br /> required prior to initiating fieldwork. If you have any questions or comments please call <br /> Lori Duncan at (209) 468-0337. <br /> Donna Heran , RENS , Director <br /> Environmental Health Division <br /> L ert G& <br /> Lori Duncan , Senior REHS Marg�orio, REHS <br /> Site Mitigation Unit IV Supervisor, Unit IV <br /> cc: Mark List, CVRWQCB <br /> Brian Gwinn , Clearwater Group , Inc. <br />