SITE INFORMATION AND CORRESPONDENCE_1988-1991

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Ground Water FS Report -9- 16 September 1991 DDRW, Sharpe Site PERMITTING 24. The Report states that 27 of 72 well samples contained total nitrates in excess of the Environmental Protection Agency (EPA) Primary DWS of 10 milligrams per liter (mg/1 ) (as nitrogen (N)) . Currently, nitrates are not being monitored in the effluent in the National Pollutant Discharge Elimination System (NPDES) permit. Nitrates and other inorganics will be included in the revised Monitoring Program. Sharpe also needs to consider the concentrations of minerals in the contaminated ground water for the prevention of scaling in the air stripping treatment system. Sharpe should be monitoring the concentrations of nitrates, total dissolved solids (TDS) and other inorganics in the existing systems. This monitoring data should be used for the remedial design and to finalize the selection of the different disposal options. 25. The current permit (Waste Discharge Requirements (WDRs) Order No. 87-026) , was issued specifically for the South Balloon Area treatment system. Because a portion of the flows from all three treatment systems will be discharged to the South San Joaquin Irrigation District Canal , specific monitoring requirements for all three treatment systems will be included in the renewal of the NPDES permit. 26. Surface water discharge is currently being used as one of the disposal options of the treated ground water at the Sharpe Site. Section 5.11 of the Draft FS Report indicates that discharge to the San Joaquin River may be further evaluated as another surface water discharge disposal option. If it is determined that discharge to the San Joaquin River is a viable disposal option for the treated ground water, then Sharpe must apply for a new NPDES permit which would be separate from the two existing NPDES permits: one for the ground water treatment systems and the other for the domestic and industrial waste water treatment system. CKW:cw