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4TE I)FtCALIFORNIA-Environmental Protecagency - . PETE WILSON, Govemor CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD CENTRAL VALLEY REGION N . ,I-T1f 3443 Routier Road,Suite A Sacramento,CA 95827-3098 PHONE:(916)255-3000 j;: r�U 0 v FAX:(916)255-3015 - tea 20 March 1996 Mr. Verrill Norwood Pioneer Chlor Alkali Company, Inc. 700 Louisiana Street 4200 NCNB Center Houston, Texas 77002 GROUND WATER IN VES TIGA TION A T ALL PURE CHEMICAL COMPANY, TRACY We have reviewed your 21 February 1996 letter in response to our 22 January 1996 request for a work plan to complete the definition of soil and ground water contamination at the All Pure facility in Tracy. Your response was that All Pure is not the source of carbon tetrachloride and is not the only source of chloroform in the ground water at the All Pure facility. You based this on your belief that All Pure's wastewater ponds are not the source of carbon tetrachloride, some chloroform is moving from an offsite source onto the site from the northeast, and the supply wells and monitoring well MW-4 which are downgradient of the ponds have not been impacted by volatile organic compounds (VOCs). We disagree with your conclusion that All Pure is not a source of carbon tetrachloride and that it is not the only source of chloroform. Samples collected from the ponds in January 1988 by Board staff contained chloroform, carbon tetrachloride, and other VOCs. The samples from Ponds 1 and 2 which Polly Lowry collected on 23 January 1996 also contained chloroform, carbon tetrachloride, and other VOCs. Our report of the 23 January 1996 inspection is enclosed for your information. We have already provided you with a copy of the 28 January 1988 inspection report. Additional evidence that the ponds are the source of the VOCs in monitoring wells MW-1, MW-2, and MW-3 is the condition of the liners in the ponds. As the enclosed inspection report notes, the liners in Ponds 1 and 2 were torn in many places along the sides and bottoms of the ponds. There have also been reports of the ponds overflowing during the winter months. During the 23 January 1996 inspection, Ms. Lowry observed that there was almost no freeboard in Pond 1 and that it appeared this pond had recently overflowed offsite to the east. As you observed in your letter, the lined surface impoundments adjacent to MW-2 and MW-3 are the likely source of inorganic parameters calcium, chloride, sodium, and total dissolved solids (TDS) in the ground water. Similarly, these surface impoundments are the likely source of VOCs in these monitoring wells. MW-3 has had detections of carbon tetrachloride, contrary to your statement, although the highest concentrations of carbon tetrachloride have been detected in MW-2. The highest concentrations of chloroform have been detected in MW-3.