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s <br /> • <br /> • FILE V11. , <br /> groundwater and surface water interactive flow nets. It is clear that a portion of the <br /> oxygenate plume is emerging in a small drainage ditch running parallel to the LCS levee. <br /> Existing monitor wells and previous boreholes have failed to define the plume in soil and <br /> groundwater. The vertical extent and lateral extent of the hydrocarbon plume must be <br /> defined considering these flow nets. The depth of the proposed boreholes must be <br /> increased to account for potential seepage forces from the LCS, primary and secondary <br /> island drainage courses. PHS/EHD and the CVRWQCB agree that shallow boreholes (6 <br /> feet) cannot cost effectively define the vertical extent of this plume in a timely manner <br /> and remobilization to complete the vertical definition would simply add to the overall <br /> cost of the assessment. <br /> Please increase the total depth and sampling depth of all boreholes proposed. At <br /> least fifty percent of all boreboles installed should be continuously cored, logged, <br /> and sampled at discrete stratigraphic intervals. Updated cross-sections are required <br /> in the next report. Additional chemical analyses are requested, please include EDB <br /> and 1,2-DCA using EPA Method 8260. Please continue to sample all monitor wells <br /> on a quarterly basis. <br /> A well/conduit receptor survey and surface water intake (pre- and post-treatment) <br /> sampling workplan were approved by PHS/EHD on July 27, 1998. Please complete <br /> the above tasks in accordance with the directive schedule listed below. <br /> The responsible party at this site is now directed to submit a very brief workplan <br /> amendment to PHS/EHD which when implemented will characterize the extent of <br /> contaminant distribution in soil, ground water, and surface waters at this site no <br /> later than August 1, 2000 S:OOpm. The work must be completed and a report must <br /> be received by PHS/EHD no later than September 1, 2000 S:OOpm. <br /> Failure to comply with PHS/EHD directives may result in referral to the San <br /> Joaquin County District Attorney's office and the CVRWQCB for formal <br /> enforcement action. Failure to comply with PHS/EHD directives may result in loss <br /> of Underground Storage Tank Cleanup Fund reimbursement. <br /> Should you have questions regarding this correspondence please contact Ron Rowe at <br /> (209) 468-0342. <br /> Donna Heran, REHS, Director <br /> Environmental Health Division <br /> Mar La orio, pervisor <br /> Ronald Rowe, Sr. REHS g g <br /> LOP/Site Mitigation Unit Site Mitigation Unit <br /> c: SJC District Attorneys Office -David Irey <br /> CVRWQCB—Marty Hartzell <br /> /15135 eight mile rd compliance letter <br /> 2 <br />