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WASTE DISCHARGE REQUIREME17fS ORDER NO. 99-079 -2- NESTLE USA-BEVERAGE DIVISION INC. RIPON FACILITY SAN JOAQUIN COUNTY Well No. 9. Several other City supply wells are threatened by the plume. One domestic supply well has been contaminated with TCE. The owner of this well has been supplied with bottled water by the Discharger. The City of Ripon and the Discharger are currently arranging a permanent alternate water supply. 8. The Discharger proposes to test an innovative approach for providing cleanup of the most contaminated groundwater in the A aquifer(shown on Attachment B)using the chemical potassium permanganate. The intent is to treat the high concentrations, up to 1000 µg/1 TCE, in groundwater(shown on Attachment C)with this in-situ chemical oxidation method and address the more dilute plume with groundwater pump and treat. In order to determine if potassium permanganate can successfully be used in conjunction with groundwater p.:mp an; tr:r:t, to provide full-scale remediation of the TCE plume,the Discharger proposes to conduct a o month pilot test. If the pilot test indicates that TCE can be successfully treated,the Discharger may propose to treat other zones of the aquifer impacted by TCE. The Discharger anticipates treatment of TCE in the pilot test zone may be effective enough to achieve concentrations below common analytical detection limits (i.e. below 0.5 µg/1)within 6 months. By comparison,the groundwater extraction well currently operating to provide remediation in the pilot test zone is estimated to require approximately 10 years to remediate groundwater in this zone to concentrations below detection limits. 9. Potassium permanganate would be injected over a period of 2-5 days into a small portion of the contaminated aquifer to oxidize VOCs to by-products which include hydrogen and chloride ions, carbon dioxide (CO2) and manganese dioxide (MnO,). The drawback of chemical oxidation of VOCs is that this process may increase total dissolved solids (TDS) levels and chloride levels in groundwater. Potassium permanganate may also cause the build up of manganese oxides on the soil grains which may result in reduction of the permeability of the aquifer. This could potentially make it more difficult and more costly to remediate the VOC contamination by pump and treat technology. An additional drawback is the difficulty to achieve adequate distribution of potassium permanganate in the aquifer which may limit the effectiveness of this technology. 10. The Discharger provided bench-scale test results to determine TDS, chloride and manganese oxide concentration increases that could be expected to occur in the pilot test zone. Calculations show that the anticipated increases in chloride and TDS levels would be minimal: respectively 32 mg/I and 55 mg/l. Background concentrations of IDS in shallow groundwater within the pilot test zone ranged from 269 to 726 mg/1. Chlorides ranged from 33 to 98 mg/l. The secondary (California and Federal) maximum contaminant levels (MCLS) for chloride and TDS are 250 mg/1 and 500 mg/l,respectively. The Discharger has estimated that the permeability of the aquifer would only be reduced minimally. 11. The Discharger has submitted a Monitoring Plan. The plan consists of evaluating the TCE concentrations in the treatment zone and other VOCs and concentrations of by-products listed above. The Discharger will also perform aquifer tests to determine if the permeability of the aquifer has been reduced in the treatment zone.