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California Rem,,,)nal Water Quality C,,,trol Board Central Valley Region Robert Schneider,Chair Winston H. Hickox Gray Davis Secretaryfor Sacramento Main Office Governor Environmental Internet Address: http://www.swrcb.ca.gov/rwgcb5 Protection 3443 Routier Road,Suite A,Sacramento,California 95827-3003 Phone(916)255-3000•FAX(916)255-3015 5 February 2001 Mr. Tom Guido Triple E Produce P.O. Box 239 Tracy, California 95378 EXTRACTION AND TREATMENT OF GROUND WATER, TRIPLE E PROD UCE, TRACY, SAN JOAQUIN COUNTY We have reviewed the 19 January 2001 Fourth Quarter 2000 Groundwater Monitoring Report (QMR) submitted by Condor Earth Technologies, Inc. (Condor) for Triple E Produce. In the transmittal letter for the QMR, Condor concludes that"Additional extraction and treatment will not likely improve aquifer quality more rapidly than the natural attenuation process(es) at work at the site" and requests "that the site be closed with no further action required by the Regional Board." As discussed below, we do not agree with the conclusion and, therefore, cannot grant the request. As part of the groundwater cleanup process, extracted, contaminated groundwater was aerated in a pond that was the initial source area of the groundwater contamination and allowed to infiltrate back into the subsurface. Monitoring well MW-1, upgradient from the pond and initially used as a background well, had a maximum chloroform concentration of 200 µg/1 in September 1997, approximately one year after the groundwater extraction and treatment system began operation. Prior to the system operation, the chloroform concentration in MW-1 exceeded 15 µg/1 in only one of 23 groundwater samples. Since March 1996, the chloroform concentration in MW-1 has not been less than 26 µg/1 (23 samples). Board staff concluded that, due to the infiltration of the treated water at the source area, groundwater mounding occurred beneath the pond and chloroform migrated upgradient from the source to monitoring well MW-1. In a 30 March 1999 letter, Board staff approved diverting extracted groundwater from the aeration pond to the plant treatment facility, thereby reducing the flow to the aeration pond. By Spring 2000, water was still present in the aeration pond. In May 2000, Triple E shut down its groundwater extraction system with Board staff approval to observe the chloroform concentration response. Within 30 days of the system shutdown, the aeration pond was dry. According to the QMR, two wells (MW-4A and MW-7) had their lowest chloroform concentrations ever during the most recent monitoring event. Additionally, the chloroform concentrations have decreased in MW-1 since flow was reduced to the aeration pond. Board California Environmental Protection Agency 0 Recycled Paper The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. For a list of simple ways you can reduce demand and cut your energy costs,see our Web-site at http://www.swrcb.ca.gov/rwgcb5