FIELD DOCUMENTS AND WORK PLANS 1992-1999

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0 • WASTE DISCHARGE REQUIREMENTS -2_ MARLEY COOLING TOWER COMPANY SAN JOAQUIN COUNTY (RAP) and to implement all measures necessary to remediate existing site contamination. 6. The DTSC, following discussions with Board staff, formally adopted the RAP on 29 August 1990, which included the conceptual design of the ground water remedial project. 7. The recommended ground water remedial action in the RAP includes the discharge of up to 0.72 mgd of treated ground water and storm water to the Stockton Diverting Canal . In order to minimize the local dewatering of the aquifer, recharge, reuse, and reinjection of the treated ground water and/or storm water, were to be evaluated as discharge alternatives. The findings were that reinjection into the shallow zone aquifer is technically feasible and utilization of reinjection would aid in ,flushing contaminants from the soils beneath the former retort pit. Therefore, approximately 5% of the treated water is reinjected into the shallow soils in the area of the retort pit. The injection water is then recaptured by the ground water extraction system. 8. The Discharger has been operating a treatment system for contaminated ground water and storm. water since October 1987. The discharge is presently regulated by Order No. 91-035, adopted by the Board on January 25, 1991. Revision of the current permit is required under Chapter 5.5, section 13380 of the Water Code for an increase in the treated water flow from the treatment plant and to incorporate reinjection of approximately 5% of the treated water for the purposes of flushing soils contaminated with chromium, copper, and arsenic attributed to the former wood preserving process. Full capture of reinjected treatment water by the ground water extraction system is in place. 9. The site is divided into two areas, the North Yard and the South Yard. All past wood treatment activities were conducted on the North Yard. Rain falling on the North Yard would become contaminated after contact with treated cooling tower components. This contaminated rainwater is collected in a storm drain system and is past through the treatment plant in the northeast portion of the site. Due to storage of treated wood products on the MCTC South Yard, some wood treating chemicals had been detected in the storm water runoff from the South Yard. The South Yard surface has been cleaned and residual contamination in pipes and ditches removed as part of the remedial actions undertaken by the Discharger. Runoff from the South Yard is not regulated. 10. The Discharger, has expanded the existing on-site treatment facility to treat flows to 0.72 mgd, discharging to the same outfall point in the Stockton Diverting Canal . The expansion of the treatment plant and the increase in ground water extraction are needed to control contaminant migration and remediate the underlying aquifer to meet cleanup levels as well as treat storm water. Ground water will be extracted from 17 extraction wells on and off-site.