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California 13;gional Water Quality Corol Board, <br /> a r' <br /> Central Valley Region �. <br /> Katherine Hart, Chair <br /> Linda S.Adams <br /> Secretary/or 11020 Sun Center Drive#200,Rancho Cordova,California 95670-6114 Arnold <br /> Environmental Phone(916)464-3291 -FAX(916)464-4645 Schwarzenegger <br /> Protection hap://w .`•vaterboards.ca.gov/centralvalley Governor <br /> 3 September 2010 RECEIVED <br /> Nestle USA Inc. SEP 13 2010 <br /> Attention: Mr. Mike Desso ENVIRONMENTAL HEALTH <br /> 800 North Brand Boulevard DEPARTMENT <br /> Glendale, California 91203 <br /> STOCKTON AVENUE GROUNDWATER EXTRACTION SYSTEM SHUTDOWN REQUEST, <br /> FORMER NESTLE USA INC. FACILITY, RIPON, SAN JOAQUIN COUNTY <br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff has <br /> reviewed the 7 July 2010 Stockton Avenue Groundwater Extraction System Shutdown <br /> Request letter. The letter was prepared by Environmental-CostManagement,-Inc , on behalf <br /> of Nestle USA, Inc. (Nestle) for the former Nestle coffee decaffeination facility project located <br /> at 230 Industrial Avenue, Ripon, California. <br /> The letter proposes the shutdown of the Nestle groundwater extraction system currently <br /> operating at 519 Stockton Avenue in Ripon. In 1999, Nestle constructed the groundwater <br /> extraction system to remove trichloroethene (TCE) and its breakdown products that had <br /> leaked from the City of Ripon industrial waste sewer line under Stockton Avenue, near its <br /> intersection with Fourth Street. Between 1957 and 1970, during manufacture of <br /> decaffeinated coffee, Nestle routinely discharged water contaminated with TCE into the <br /> industrial sewer line. Apparently, the contaminated water leaked into the soil and <br /> groundwater beneath Stockton Avenue as it flowed through the industrial sewer conveyance <br /> system on its way to the City of Ripon sewer ponds located adjacent to the north side of the <br /> Stanislaus River. Nestle has concluded that the system has successfully remediated the <br /> source area associated with the sewer line release because contaminant concentrations <br /> including TCE and its breakdown products cis-1,2-dichloroethene (cis-1,2-DCE) and vinyl <br /> chloride have decreased to low asymptotic levels. <br /> Central Valley Water Board staff agree that contaminant concentrations appear to have <br /> reached low asymptotic levels in shallow extraction well E-2 and the shallow monitoring wells <br /> at the Stockton Avenue release site. TCE concentrations in E-2 and source area monitoring <br /> well M-86 have dropped from highs of approximately 1,400 micrograms per liter (µg/L) in <br /> 2000 to approximately 6 to 8 µg/L in 2010. Therefore, at this time Nestle may shut off <br /> groundwater extraction well E-2 with the following conditions: - <br /> 1. Nestle must evaluate rebound concentrations of contaminants in the shallow <br /> monitoring wells. Nestle should collect and analyze groundwater samples for TCE <br /> and its-breakdown-products-on a monthly basis during the first quarter-after <br /> shutdown, and quarterly during the second, third, and fourth quarters. The samples <br /> should be collected from the following wells: E-2, M-8A, M-813, and M-52B. <br /> California Environmental Protection Agency <br /> vaRecycled Paper <br />