Laserfiche WebLink
SETTLING DRY CLEANING DEFENDANTS <br /> LINCOLN VILLAGE CENTER GROUNDWATER TREATMENT SYSTEM <br /> SAN JOAQUIN COUNTY <br /> INFORMATION SHEET <br /> The Settling Dry Cleaning Defendants, as defined by Consent Decree (and listed in Attachment A to <br /> the permit),proposes to discharge waste from a groundwater treatment system designed to remove <br /> volatile organic compounds (VOCs) from groundwater and investigation derived residual fluids <br /> collected during ongoing investigation,remediation, and monitoring activities. The groundwater <br /> treatment system is designed to treat 300 gpm (430,000 gpd) of extracted groundwater, and residual <br /> fluids collected during ongoing investigation,remediation, and monitoring activities. About 200 gpm <br /> (290,000 gpd) will be discharged to a storm drain in the City of Stockton, tributary to Fourteen Mile <br /> Slough, and then the San Joaquin River. <br /> Pumped groundwater will be treated by passing it through an air stripper, and then passing it serially <br /> through two exchangeable activated carbon units prior to being discharged to the storm drain. The <br /> activated carbon units are regenerated or disposed off-site. <br /> Tetrachloroethylene (PCE),trichloroethylene(TCE), cis-1,2-dichloroethylene (DCE),methylene <br /> chloride, and 1,2-dichloroethane (1,2-DCA)have been identified in the groundwater as constituents of <br /> concern. In addition, it is suspected that the constituents benzene,toluene, xylene, and ethylbenzene <br /> (BTEX), lead, and also methyl tertiary-butyl ether (MTBE) or other oxygenate compounds may <br /> become present in water pumped from extraction wells due to two fuel contamination sites which are <br /> also present at the Lincoln Center. The proposed treatment plant is expected to treat the volatile <br /> organic compounds to non-detectable levels. It is currently unknown if the treatment plant will <br /> effectively remove oxygenate compounds. This Order requires a treatment performance evaluation to <br /> show the effluent limitations can be met, and also ongoing monitoring for constituents of concern. <br /> Effluent limitations have been set as follows: <br /> a) 30 Day median concentrations are set at a practical quantitation limit(PQL) of 0.5 µg/1 for all <br /> VOCs and BTEX constituents. A `median' is used rather than an `average' to allow for the <br /> detection of a constituent in individual samples without automatically causing violation of the <br /> monthly limitation. The 30-day average concentration for lead is established at 5 µg/l, one-tenth the <br /> MCL for lead. The 30-day average concentration MTBE is established at 35 µg/1,the State of <br /> California Drinking Water Action Level. <br /> Routine effluent monitoring, following onset of full scale operation,will be conducted monthly. <br /> The treatment technologies are not normally subject to sudden upset or bypass, so rapid changes in <br /> effluent concentrations are not expected. If detectable concentrations of BTEX or VOC <br /> constituents are found,the monitoring program requires weekly monitoring of the effluent until <br /> `non-detected' conditions are reestablished. The effluent monitoring is not a substitute for process <br /> control monitoring by the Discharger. <br /> b) A daily maximum effluent limitation is set to allow for some effluent quality variation and for the <br />