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e 0 <br /> .` California Regional Water Quality Control Board _ <br /> vCentral Valley Region <br /> Winston H.Hickox Steven T. Butler, Char,i . c, I <br /> Secretaryfor 1 2�rn� Gray Davis <br /> Sacramento Main Office Governor <br /> Environmental Internet Address: http://www.swrcb.ca.gov/—mgcb5 <br /> Protection 3443 Routier Road,Suite A,Sacramento,California 95827-3003 <br /> Phone(916)255-3000•FAX(916)255-3015 <br /> 29 June 2000 <br /> Mr. David R. Lieb <br /> Marley Cooling Tower Company <br /> 150 North Sinclair Avenue <br /> Stockton, CA 95215 <br /> TRANSMITTAL OF REPORT PRESENTING RESULTS OF INJECTION WELL <br /> SIMULATIONS, MARLEY COOLING TOWER COMPANY(MCTC), SAN JOAQUIN <br /> COUNTY, Case No. 2971 <br /> We have reviewed the Transmittal of Report Presenting Results of Injection Well Simulations, <br /> dated 13 September 1999, as prepared by Dudek & Associates, Inc. (Dudek). MCTC proposes <br /> an alternative disposal option by injecting treated groundwater, as effluent, back into the aquifer. <br /> Currently, treated groundwater is discharged to the Stockton Diverting Canal under the terms of <br /> NPDES permit No. CA0081787 (Waste Discharge Requirements Order No. 93-221) since <br /> approximately 1988. The Board's Water Quality Control Plan, Central Valley, Sacramento <br /> River and San Joaquin River Basins(Fourth Edition) (Basin Plan) encourages discharge to land <br /> as the primary objective, and secondarily to surface water. However, the water quality objectives <br /> for groundwaters require that the discharge does not exceed naturally occurring background <br /> concentrations, as the objectives are relevant to the protection of designated beneficial uses. <br /> Therefore, prior to allowing discharge to groundwater to occur, MCTC must establish a <br /> background concentration for hexavalent chromium, the constituent of concern, and verify that <br /> the treatment system can meet background in their effluent. MCTC should use EPA Method <br /> 7199, Determination of Hexavalent Chromium in Drinking Water, Groundwater, and Industrial <br /> Wastewater Effluents by Ion Chromatography. The Method Detection Limit should be 0.5 ppb <br /> (9g/L). Effluent water quality would also be required to meet background concentrations for <br /> total dissolved solids (TDS), which is commonly increased above background levels during the <br /> treatment process. <br /> As discussed in our meeting at MCTC on 12 June 2000, the Cal/EPA Office of Environmental <br /> Health Hazard Assessment (OEHHA) established a Public Health Goal (PHG) for hexavalent <br /> chromium in drinking water (February 1999). The PHG is based on a health protective criterion <br /> of 0.2 ppb for hexavalent chromium. If naturally occurring background concentrations for <br /> hexavalent chromium are less than this value, which is improbable because of the detection limit <br /> of 0.5 ppb, then the water quality goal would be the detection limit. <br /> If MCTC decided to pursue this route, additional information would be required to be submitted <br /> in a new Report of Waste Discharge for revision of Order No. 93-221. <br /> California Environmental Protection Agency <br /> 0d Recycled Paper <br />