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Former Shell Service Station Page 2
<br /> 1313 East Charter Way June 26, 2009
<br /> Stockton, California 95205
<br /> To comply with the State Water Resources Control Board Resolution No. 2009-0042, the
<br /> EHD approves the following monitoring and samplirig schedule:
<br /> • Semi-annually collect groundwater from monitoring well MW-6 and analyze the
<br /> samples for 1,2-DCA, only.
<br /> • Annually collect groundwater from MW-2, N W-3, MW-4, MW-5, MW-7, MW-8, and
<br /> MW-9. Analyze samples from MW-2 for me hyl tertiary-butyl ether (MTBE), TPH-g,
<br /> BTEX, and 1,2-DCA. Analyze samples fro MW-3, MW-4, MW-5, MW-7, MW-8,
<br /> and MW-9 for 1,2-DCA, only.
<br /> CRA compared groundwater Environmental Screening Levels (ESLs) from Table E-1 of
<br /> the San Francisco Bay Regional Water Quality Control Board document Screening for
<br /> Environmental Concerns of Sites with Contaminated Soil and Groundwater — November
<br /> 2007 (revised May 2008) to current groundwater concentrations of 1,2-DCA at this site,
<br /> however the residual contaminant concentrations of TPH-g, BTEX, and 1,2-DCA in soil
<br /> should also be compared to ESLs and Califor is Environmental Protection Agency
<br /> California Human Health Screening Levels (CHH Ls), and the need to collect soil gas
<br /> samples should be evaluated. In addition, please submit estimates of the residual TPH-g,
<br /> benzene, and 1,2-DCA masses in soil-and group water to the EHD, along with the soil
<br /> gas intrusion evaluation by September 16, 2009. If contaminant concentrations in soil
<br /> exceed gross contamination, a rational for safely leaving the mass in place must be
<br /> provided.
<br /> If you have any questions regarding this letter, please contact Vicki McCartney at (209)
<br /> 468-9852 or by email at vmccartneygssjcehd.com.
<br /> Sincerely,
<br /> Victoria L. McCartney, REHS Nuel C. Henderson, Jr., PG
<br /> Senior Registered Environmental Health Specialist Engineering Geologist
<br /> c: Mr. Joseph W. Neely, PG, Conestoga-Rovers & Associates, 19449 Riverside Drive,
<br /> Suite 230, Sonoma, California 95476
<br /> Mr. Jaynes L.L. Barton, PG, California Regional Water Quality Control Board Central
<br /> Valley Region, 11020 Sun Center Drive, Suite 200, Rancho Cordova, California 95670
<br />
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