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STATE OF CALIFORNIA- Environmental Protection*cy PETE WILSON, Governor CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD ,- CENTRAL OARD ,_CENTRAL VALLEY REGION 3443 Routier Road, Suite A ,. ._`� r I i— ---• Sacramento,CA 95827-3098 f` Pr1 '• OO . PHONE: (916) 255-3000 jtlg �'{uvy ' 9 f' Jn FAX: (916) 255-3015 18 August 1994 Mr. Tom Miazga Hydrite Chemical Company 300 N. Patrick Boulevard Brookfield, Wisconsin 53008 SURFACE IMPOUNDMENT (POND) CLOSURE, REVISED CONFIRMATION SAMPLING PLAN, FIRST AND SECOND QUARTER GROUND WATER MONITORING REPORTS, USC STOCKTON, SAN JOAQUIN COUNTY We received the "Pond Closure/Confirmation Sampling Plan (Revised) on 12 August 1994, and the first and second quarter 1994 ground water monitoring reports on 4 August 1994. The semi-annual ground water monitoring results from the 8 March 1994 sampling event yielded halogenated volatile organics in ground water in all four monitoring wells. The well closest to the surface impoundment (MW-3) has the highest levels of 1,1- DCE. The-slant soil borings drilled in 1992 yielded 1,1,-DCA in soil 60 feet below the surface impoundment. Ground water is 70 to 80 feet below surface and the flow direction appears to have changed due to recharge after the drought or to different agricultural pumping. The above two mentioned monitoring reports indicate that there currently are no monitoring wells down gradient of the surface impoundment. The Plan states that closure of the surface impoundment will include removal of all liquids and sludges and the top six inches of the clay liner. Seven auger borings will be taken of the remaining clay/soil liner for chemical characterization to demonstrate clean closure. Soil sampling depths will be at the 1 and 2 foot level below the remaining surface impoundment. Corresponding samples will also be taken outside of the surface impoundment influence and analyzed for background constituent levels. Due to the possibility of halogenated organics originating from the surface impoundment, 3 of the 7 borings from the surface impoundment must be analyzed for organics using EPA method 8010/5030. One of which must be in the area of the discharge pipe. Due to the potential volatilization in the upper layers of the surface impoundment, the organic samples need only be analyzed in the soil/clay at the two foot level below the surface level. The remaining constituents and boring locations identified in the Plan are reasonable and approved for confirmation. Prior to disposing the waste water and sludges off site, the chemical characterization of those wastes must be submitted to this office (laboratory data sheets are sufficient). Please inform me of the date of confirmation sampling so we have an opportunity to collect split samples of the borings.