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Bert E. Van Voris - 8 - 17 September 2004 Supervising Engineer treatment is the minimum level of treatment capable of consistently and reliably producing a wastewater with this requisite quality. In support of the proposed target BOD range of 40— 50 mg/L,the RWD indicates that such levels have been determined adequate for irrigation disposal of winery wastewater in unspecified WDRs adopted by an unspecified regional water quality control board. The technical and environmental basis for these effluent limits may be considered, but will not be determinant. Musco should identify which regional board it is referencing, and list at least one representative WDRs order prescribing effluent BOD limitations reflecting the proposed target range. An effluent BOD limitation in WDRs may not be sufficient for irrigation with treated winery wastewater under a recycled water project scenario. Further, as "BOD levels in [the proposed] range can require management of odor generation in the water prior to irrigation"s means that the proposed BOD range is too high for the discharge to be considered a recycled water project. The technology Musco proposes for the higher salinity wastestreams (aerobic treatment followed by ultrafiltration) is capable of reducing BOD to less than 10 mg/L. Use of this technology on all wastestreams would guarantee an effluent quality consistently commensurate with that of"recycled water." Accordingly, while the proposal to treat higher salinity wastestreams with this technology and RO reflects the implementation of best practicable treatment and control (BPTC),the proposal to blend this low-BOD RO permeate in the reservoir with untreated high-BOD wastewater does not. To fully reflect BPTC, all wastewater impounded in the reservoir must meet the quality"suitable for onsite storage and land application," particularly as the issue of the reservoir lining has not been satisfactorily addressed.6 It appears that dual biological treatment trains will be necessary (one for high salinity wastestreams prior to RO treatment, the other for lower salinity wastestreams prior to reservoir discharge) Target TDS Levels. The RWD/RWR grossly characterizes first encountered groundwater in these areas based on one sampling event of three wells, only one of which is a dedicated groundwater monitoring well. The RWD/RWR should provide the design details of this well, as well as a technical report describing this well and its installation, such as information specified in STANDARD INFORMATION REQUIREMENTS FOR GROUNDWATER MONITORING WELL INSTALLATION REPORTS. Table 5, which characterizes the quality of various wastestreams, should provide information on mass loadings from each wastestream. The 26 May 2004 Regional Board letter cautioned Musco to recognize that typical irrigation practices will concentrate waste constituents more than three times, and recommended Musco utilize the actual concentration factor for local practices in identifying the target concentration for IDS and IDS constituents. The letter stated, "the concentration of any waste constituent in leachate moving below the root zone cannot exceed the concentration of the constituent determined acceptable in groundwater by the Regional Board." Because Musco proposes to recycle its treated wastewater for agricultural irrigation, however, the letter stated that Musco's "effluent quality need not be better in quality than the water supply used for irrigation in the reuse area." The