SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

REGIONAL BOARD RESPONSE(SARCB/OCC FILE.A-1483) -21- PETITION FOR REVIEW OF WASTE DISCHARGE REQUIREMENTS ORDER NOS. R5-2002-0083 AND R5-2002-0084 CITY OF STOCKTON REGIONAL WASTEWATER CONTROL FACILITY SIXTH BASIS: DAILY MAXIMUM EFFLUENT LIMITATIONS Stockton requests that the State Board direct the RWQCB to delete all the interim and final daily maximum effluent limitations. This request is based on new information that was not brought forward during the public comment period and should be excluded from the record before the State Board. Notwithstanding, the Regional Board provides the following response. 40 CFR 122.45(d)(2)requires weekly average and monthly average effluent limitations for publicly owned treatment works (POTWs). However, EPA recommends the implementation of maximum daily limitations (MDL) for toxic pollutants. EPA provides the rationale for this recommendation on page 96 of the TSD, "...EPA recommends establishing an MDL (or a maximum test result for chronic toxicity)for toxic pollutants and pollutant parameters in water quality permitting. This is appropriate for at least two reasons. First, the basis for the 7-day average for POTPs derives from the secondary treatment requirements. This basis is not related to the need for assuring achievement of water quality standards. Second, a 7-day average, which could comprise up to seven or more daily samples, could average out peak toxic concentrations and therefore the discharge's potential for causing acute toxic effects would be missed. A MDL, which is measured by a grab sample, would be toxicologically protective of potential acute toxicity impacts." Turbidity and coliform are not toxic pollutants,however, the MDLs are required to meet the Title 22 reclamation requirements, as recommended by DHS for the protection of public health. SEVENTH BASIS: MASS LIMITS Stockton requests that the State Board direct the RWQCB to delete the mass limits for mercury, lindane, endrin aldehyde, and DDT Mercury: The SIP states, "For bioaccumulative priority pollutants for which the receiving water has been included on the CWA Section 303(d) list, the RWQCB should consider whether mass loading of the bioaccumulative pollutant(s)should be limited to representative, current levels pending TMDL development in order to implement the applicable water quality standard." Health advisories by the Department of Health Services remain in effect for human consumption of fish in the Delta, including the SJR at Stockton, due to excessive concentrations of mercury in fish flesh. These current warnings indicate that the receiving water has no assimilative capacity for mercury. Any increase of mercury in the RWCF discharge would violate the Basin Plan's narrative toxicity objective. Therefore, interim mass-based effluent limitations were adopted for mercury, limiting the discharge to representative, current levels pending TMDL development (see Table 11-6 of Order R5-2002-0083). It is recognized that the SIP recommendation to consider interim limitations at"representative, current levels"could effectively place a cap on future growth of the RWCF.service area. Therefore, Order R5-2002-0083 requires the development of an offset program,which could be used to offset mercury loads over and above the interim limitation. If a TMDL is established and the discharge mass load still exceeds that limitation, this program could be used to offset discharges over and above the TMDL. In this context the term"offset"refers to reductions in loadings of the pollutant to the Delta and SJR watershed achieved through the Discharger's actions from an appropriate source. This includes