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1.0, <br /> California Regional Water Quality Control Board - <br /> �■/ Central Valley Region <br /> Robert Schneider Chair <br /> Alan C.Lloyd Ph.D. - Sacramento Main Office Arnold Schwarzenegger <br /> Secretary for Internet Address: http://�.s�b.ca.gov/rwqcb5 b.ca.gov/rwycb5 <br /> Environmental <br /> 11020 Sun Center Drive#200 Rancho Cordova,CA 95670-6114 Governor <br /> Protection Phone(916)464-3291 Fax(916)464-4797 no <br /> 19 May 2005 ° •Fr��VED <br /> Mr. AWAY 2 3 2005 <br /> Dia Mike Walnut <br /> 9MONMENT HEALTH <br /> Diamond Walnut Growers Ina CES <br /> 1050 South Diamond Street PEVIT/SERVI <br /> Stockton, California 95201 <br /> CLEANUP PROGRESS, DIAMOND WALNUT GROWERS, STOCKTONPLANT RELEASE SITE, <br /> 1050 SOUTH DIAMOND STREET, STOCKTON, SAN JOAQUIN COUNTY <br /> Diamond Walnut Growers, Inc. (DWG) is conducting cleanup at its Stockton Plant at 1050 South <br /> Diamond Street in San Joaquin County(site), because of hexavalent chromium discovered in soil and <br /> groundwater beneath its cooling tower. The release polluted groundwater and impaired its beneficial <br /> use. Central Valley Regional Water Quality Control Board(Regional Board) staff reviewed the <br /> 21 January 2005 Bench Scale Treatability Study for Reducing Hexavalent Chromium (Treatability <br /> Study) and the April 15, 2005 First Quarter Monitoring Report(QMR) submitted by ATC Associates <br /> Inc. (ATC) on behalf of Diamond Walnut Growers Inc. (DWG) for its Stockton Plant, and present the <br /> following comments. <br /> Although Table 2 that is contained in the QMR states that the concentrations are in milligrams per liter <br /> (mg/1) some of the constituent concentrations were copied from the laboratory data sheets incorrectly <br /> and are actually in micrograms per liter(µg/1). For clarification, the table below lists the detectable <br /> constituent and its highest concentration during the January 2005 sampling event and includes the <br /> applicable water quality criterion. <br /> Highest Applicable <br /> January 2005 Water <br /> Constituent Concentration in Quality Basis for Water Quality Criterion <br /> Groundwater Criterion <br /> (Ag/1) (µg/1) <br /> Total Chromium 2,600 50 California Primary Maximum Contaminant Level(MCL) <br /> Hexavalent 2,400 21 USEPA IRIS Reference Dose(RID)as a drinking water level <br /> Chromium <br /> Aluminum 320 50 USEPA Secondary Maximum Contaminant Level(MCL) <br /> Calcium 240,000 NA <br /> Chloride 420 250,000 California Secondary Maximum Contaminant Level(MCL) <br /> Chloroform 65 1.1 Cal/EPA Cancer Potency Factor <br /> Tetrachloroethene 49 0.5 Maximum Practical Quantitation Limit[California Public <br /> Health Goal 0.06 1 <br /> California Environmental Protection Agency <br /> ped Recycled Paper <br />