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Sierra-Pacific Groundwater Consultants, Inc. Y = Y <br /> Geologists, Engineers, and Compliance SpetsY1#4,'ii'" <br /> , 7_— <br /> Nov <br /> �` G6 Nov - 1 A?1 i l 2 Z <br /> October 30, 1996 <br /> Ms. Wendy Wyels, Agricultural Regulatory Unit <br /> Central Valley - Regional Water Quality Control Board <br /> 3443 Routier Road, Suite A <br /> Sacramento, California 95827-3098 <br /> Subject: Draft Monitoring and Reporting Program, Former PureGro Facility at 1905 North <br /> Broadway Avenue, Stockton, PureGro Site No. 771165, Unocal Order/Contract: 34402-1, <br /> Sierra-Pacific Project No. 94-055.08 <br /> Dear Ms. Wyels: <br /> The following letter concerning the draft monitoring program at the Broadway Avenue site was prepared <br /> by Sierra-Pacific Groundwater Consultants, Inc. (Sierra-Pacific) on behalf of Unocal. The draft program <br /> seems reasonable. However, we have the following comments: <br /> • The draft program document indicates that EPA Method 615 should be used for chlorinated herbicide <br /> analyses. Sequoia Analytical apparently uses EPA Method 8150, and Sequoia is Unocal's contract <br /> laboratory. I assume that EPA Method 615 is appropriate for this work, but I am not a chemist. <br /> Is there some problem with EPA Method 8150? <br /> • Would it be acceptable to RWQCB to limit testing for chlorinated herbicides to the closest down- <br /> gradient wells (MW-02 and MW-08). I believe that Dinoseb was detected at MW-08 last Spring, <br /> but none was detected during the most recent sampling event. <br /> • The first paragraph of page two discusses inspection and maintenance of drainage systems. To my <br /> knowledge, there are no on-site storm water drains near the paved evaporation pond areas. <br /> (916)933-1468 <br /> 4911 Windplay Drive.Suite 4 El Dorado Hilk,Califomia 95762 (916)933-3197 FAX <br />