FIELD DOCUMENTS AND WORK PLANS 1990

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INFORMATION SHEET Marley Cooling Tower Company San Joaquin County Past operational practices in the fabrication of cooling towers by the Marley Cooling Tower Company (MCTC) has caused soil and ground water contamination by copper, chromium and arsenic. In October 1987, MCTC initiated interim ground water remediation. This interim remedial action has been operating under Order No. 88-124 (NPDES No. CA0081787) . MCTC is presently permitted to discharge up to 0.37 mgd of treated stormwater and ground water to the Stockton Diverting Canal , tributary to the Calaveras River. A Remedial Investigation / Feasibility Study has been conducted and in August 1990, the final Remedial Action Plan (RAP) was approved by the DHS. The recommended ground water remedial action in the RAP included an increase of up to 0.72 mgd in the discharge of the treated ground water and/or storm water for an interim period, not to exceed 18 months. During this 18 month period, MCTC will be evaluating other discharge alternatives. Aquifer reinjection and reuse is considered a viable discharge alternative because it would minimize local dewatering of the aquifer due to overdraft and would restore the aquifer as a usable drinking water source due to recharge of the treated ground water and/or storm water. MCTC submitted a Report of Waste Discharge (RWD) in response to a Notice of Violation dated 12 July 1990. During the first quarter of 1990, MCTC exceeded the effluent limitations in Order No. 88-124 for chromium, copper and total dissolved solids. MCTC proposed in the RWD an interim expansion of the on-site ground water treatment facility to control off-site contaminant movement. An electrochemical reduction and precipitation treatment plant will be constructed and used in parallel with the existing ion exchange treatment system. Flows have been proposed to be increased to 0.59 mgd. Ground water treatment will now consist of various combinations of the following unit processes: flow equalization, reduction, precipitation, settling, filtration, pH adjustment and ion exchange. The RWD also contained a technical report on the water treatment plant's operation. The report did not adequately address the operation and maintenance procedures to be taken during wet weather events and in the case of breakthrough. A revised Operation and Maintenance Manual for the treatment plant is needed to define those measures to be taken during these events. MCTC submitted the Effluent Toxicity Program Report which demonstrated that the effluent does not have a reasonable potential to cause fathead minnow instream toxicity. However, this Report also indicated that the effluent may periodically cause acute invertebrate (Ceriodaohnia dubia) instream toxicity. More extensive invertebrate follow-up toxicity testing is needed to confirm this potential toxicity.