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Review of OU-1 FS Report -3- 7 August 1992 DDRW, Tracy 3. Storage of a portion of the treated ground water for irrigation appears to be a viable disposal alternative. It is unclear why a portion of the treated ground water cannot be used for irrigation either on- or off-base. 4. The discharge of treated ground water to a pond would be considered a waste discharge to land and would be subject to WDRs. Currently, excess flows from the IRM may be discharged to the storm water pond under WDRs No. 90-275. Monitoring of the storm water pond is required under WDRs No. 89-209. If a new pond is constructed for the disposal of the treated ground water, either the existing WDRs would be revised or Tracy would be expected to comply with the substantive requirements of our WDRs. 5. We acknowledge that evaporation will occur with any ponding of water. However, discharge of treated ground water to a pond designed for the primary purpose of evaporation is discouraged. Evaporation of treated ground water that may be potable with respect to all Primary and Secondary Maximum Contaminant Levels (MCLS) is considered a waste of this valuable resource. 6. Surface water discharge to a nearby irrigation supply canal , rather than to the Delta Mendota Canal , may be a potential disposal alternative. Discharge to these canals will require a National Pollutant Discharge Elimination System (NPDES) permit. An application for any such off-site discharge should be submitted to our office as soon as possible. Attached are the appropriate application forms. 7. Reinjection of treated ground water must comply with the State Water Resources Control Board (State Board) Resolution 68-16 (Anti-Degradation Policy) . Reinjection must be done to maintain the high quality of the (receiving) ground water. To implement this Applicable or Relevant and Appropriate Requirement (ARAR), best available technology (BAT) must be used to approximate background, unless the Board finds that it is in the public interest to allow a level above background which still meets water quality objectives for all constituents. This ARAR must be reflected in the Draft Final OU-1 FS Report. 8. Recent discussions with Tracy has indicated that it is continuing to pursue the purchase of the property to the east of the base to Banta Road. If the property is purchased, then a portion of the property could be used for the construction of a storage pond or a spreading basin for the treated ground water. The treated ground water could also be used for irrigation, should a portion of the purchased property be leased out for farming. 9. Table 2.4-2 summarizes the evaluation of each of the disposal alternatives. Several of the alternatives were dismissed. Many of the dismissed disposal alternatives should be retained for further evaluation because multiple alternatives may be needed to dispose of the high volume of water estimated to need treatment. Below are the disposal alternatives which were not considered or were dismissed but may become more viable with further investigation: a. Reuse by local industry; b. Spray irrigation; c. Storage and reuse for irrigation; d. Discharge to surface water;