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STATE OF CALIFORNIA-Environmental Protectloency . PETE WILSON, Governor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD <br /> CENTRAL VALLEY REGION <br /> 3443 Routier Road, Suite A - <br /> i <br /> Sacramento, CA 95827-3098 N <br /> PHONE: (916)255-3000U <br /> IF <br /> FAX: (916)255-3015Jgt()( <br /> sj(�(j]�� �w�m <br /> 22 December 1994 Jllj^V[VJIa_ l� O <br /> DEC 2 8 1994 <br /> Mr. Tom Miazga <br /> USC/ A Division of Hydrite Chemical Company ENVIRONMENTAL HEALTH <br /> 300 N. Patrick Boulevard PERMIT/SERVICES <br /> Brookfield, Wisconsin 53008 <br /> SURFACE IMPOUNDMENT CLOSURE, USC/A DIVISION OF HYDRITE CHEMICAL <br /> COMPANY, STOCKTON <br /> Waste Discharge Requirements Order No. 92-034 required USC to close or retrofit the surface <br /> impoundment by October 1993. USC attempted to clean close the surface impoundment under <br /> Chapter 15 standards. The 18 November 1994 technical report 'Pond Closure" submitted by Harding <br /> Lawson Associates (HLA) outlined the removal of the surface impoundment waste, contaminated <br /> liner and contaminated subsoils during the closure process. Confirmation sampling revealed that all <br /> materials contaminated with volatile organic compounds and 82% of the sodium found beneath the <br /> surface impoundment were excavated. The remaining subsoils contain levels of sodium that would <br /> not impact ground water quality. Depth to ground water is 70 feet. <br /> The report estimates that at the start of closure, 190,000 pounds of sodium were present in the <br /> impoundment and subsoils in excess of background concentrations. Excavation of 2,500 yards of <br /> contaminated subsoils resulted in a removal of an estimated 156,000 pounds of the total sodium <br /> present. HLA estimated that 1,300 yards of soil remain in place with sodium concentrations above <br /> background. Analytical testing of soil borings indicate sodium migration was limited to 20 feet <br /> beneath the surface impoundment. Prior to back filling the excavation, the soils at the base of the <br /> excavation were scarified, mixed and recompacted to homogenize the subsoils. The excavated hole <br /> was then backfilled with clean fill dirt and compacted to 90% relative compaction up to the final <br /> grade. <br /> Monitoring wells installed adjacent to the surface impoundment have not detected chemicals <br /> attributable to wastewater within the surface impoundment. Staff will propose that the Regional <br /> Board, at the 27 January 1995 Board meeting, rescind the current WDRs and concur with closure. <br /> You will be sent a copy of the rescission information prior to the Board's consideration. <br /> If you have(+AGHN <br /> any questions please call James Brathovde at (916) 255-3137. <br /> G \.V <br /> G K. <br /> Senior Engineer <br /> cc: Mr. Mike Infurna, San Joaquin County Environmental Health Department, Stockton <br /> Ms. Brooke Birke, Neu miller and Beardslee, Stockton <br />