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California*gional Water Quality Conol Board <br /> Central Valley Region <br /> j <br /> Karl E.Longley,ScD,P.E.,Chair`' <br /> Arnold <br /> Linda S.Adams <br /> Sacramento Main Office Schwarzeneg <br /> Secretaryfor 11020 Sun Center Drive 71200,Rancho Cordova,California 9567b-6114 <br /> Governor <br /> Environmental Phone(916)464-3291 •FAX(916)464-4645 <br /> Prorecrion http://www_waterboards.ca.gov/centralvalley <br /> DAPI 2 3 20008 <br /> ENVIRi) MENT HEALTH <br /> 22 January 2008 PE'9"T/SERVICES <br /> Mr. Frank Barone <br /> Miller Springs Remediation Management, Inc. <br /> 2480 Fortune Dr., Suite 300 <br /> Lexington, KY 40509-4168 <br /> MONITORING WELL MW-30 WORK PLAN, REVISION TO SOIL SAMPLING <br /> SCHEDULE, OXYCHEM, 1904 WEST CHARTER WAY, SAN JOAQUIN COUNTY <br /> Occidental Chemical is remediating soil and groundwater that contains nitrogen and <br /> pesticides at its former agricultural chemical retail facility at 1904 West Charter Way. <br /> Miller Springs Remediation Management Inc. (MSRMI) and Geomatrix Consultants <br /> implemented a full-scale phytoremediation planting in 2003 in order to exert hydraulic <br /> control of shallow groundwater, and remove nitrate and volatile organic compounds <br /> from soil and groundwater through tree growth processes. <br /> Central Valley Regional Water Quality Control Board (Regional Water Board) staff have <br /> reviewed the following reports prepared by Geomatrix Consultants that document the <br /> progress of the remediation. <br /> November 2007 Second Semi-annual and Annual 2007 Groundwater Monitoring <br /> Report (Annual 2007 Report) <br /> 10 August 2007 First Semiannual 2007 Phytoremediation Soil Sampling Report (Soil <br /> Sampling Report) <br /> The groundwater data show that a shallow off-site monitoring well (MW-27) contained <br /> 1,2-dichloropropane (1,2-DCP) at concentrations of 2.7 and 11 ug/L in the last two <br /> sampling events. This exceeds the threshold criteria of 0.5 ug/L for plume migration, as <br /> stated in the 20 October 2005 Revised Groundwater Cleanup and Contingency Plan. <br /> These exceedances call for MSRMI to install an additional monitoring well down- <br /> gradient of MW-27 to evaluate the rate and extent of plume migration. MSRMI will <br /> implement in situ bioremediation if the new downgradient monitoring well shows <br /> consistent exceedances of 1,2-DCP. The threshold concentration of 1,2-DCP for <br /> human health protection is 280 ug/L. <br /> California Environmental Protection Agency <br /> ¢a Recycled Paper <br />