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. is • • <br /> - `- Department of Toxic Substances Control <br /> Alan C,Lloyd,Ph.D. 8800 Cal Center Drive Arnold Schwarzenegger <br /> Agency Secretary Sacramento,California 95826-5200 Governor <br /> CaUEPA <br /> May 16, 2005 <br /> Ms. Betsy Brunswick <br /> PG&E Environmental Services <br /> P.O. Box 7640 <br /> San Francisco, California 94120 <br /> APPROVAL ON THE FEBRUARY 2005 WORK PLAN FOR THE PG&E <br /> MANUFACTURED GASPLANT SITE, STOCKTON,CALIFORNIA ` <br /> Dear Mr. Brunswick: <br /> The Department of Toxic Substances Control (DTSC) has reviewed ENV America's <br /> April 29, 2005 response to DTSC's April 1, 2005 comments on the "Work Plan to <br /> Address Groundwater Conditions in the Vicinity of MW-26R"for the PG&E former <br /> manufactured gas plant to Stockton, California, Acenaphtlene concentrations in <br /> groundwater samples collected from MW-26R have increased from 9.6 to 19 <br /> micrograms per liter(ug/L) in 1997 and 1998 and trending up to 100 ug/L in 2004. The <br /> work plan proposes to install an additional monitoring well approximately 270 feet to 113 <br /> below the ground surface to serve as a sentry well. The work plan also proposes to <br /> decommission eight existing wells. The eight existing wells should be decommissioned <br /> once PG&E has fully assessed the groundwater and propose an adequate response <br /> action. PG&E may need to monitor subsequent amended remedy, DTSC comments <br /> have been addressed and the work plan is approved. <br /> PG&E should provide a report that explains why the increase in concentrations trends In <br /> MW-26R are not following the model used in the March 1998 Remedial Action Plan and <br /> recorrstriend actions that need to be-takerr. -The wells can be decommissioned after this <br /> evaluation is concluded and it is absolutely clear the wells will not be required for future <br /> monitoring of groundwater conditions. <br /> Please contact Mr. Duane White at(916)255-3585 at least 48 hours before installing <br /> the new well. If you have any questions or comments, please contact Mr. Duane White. <br /> Si rely, <br /> Fe ando Amador, P.E., Chief <br /> Sacramento Responsible Party Unit <br /> 0 Printed on Recycled Paper <br /> Z 'd 8110 ON S301A83S ' AOddnS 1V1NIMOUAN3 WUbO 6 S0061 'NOP <br />