SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

FACT SHEET ORDER NO. R5-2002- -30- CITY OF STOCKTON REGIONAL WASTEWATER CONTROL FACILITY SAN JOAQUINCOUNTY LATE REVISIONS detect Basin Plan objective are required. A TMDL for mercury in the Delta is scheduled for completion by December 2005 while the TMDL for Group A pesticides is scheduled for December 2011. The US EPA has not presented a TMDL completion date for dioxin/furans and PCBs. In addition to the 303(d) listing, the Basin Plan sets forth a water quality objective which requires that organo-chlorine pesticides not be present in the water column in detectable concentrations. The SIP designates acceptable minimum levels for lindane, endrin aldehyde and DDT at 0.02 µg/1, 0.01 µg/I and 0.01 µg/1,respectively. The detectable organo-chlorine pesticide effluent concentrations and corresponding reporting levels are above the SIP minimum levels and exceed the Basin Plan objective. Because of the SJR 303(d) listing, no mixing zone or dilution credits are available for these constituents. Based on the considerations listed above, effluent limitations for Group A pesticides are needed within the Order. 11.2 Reasonable Potential Analysis Priority pollutant constituents were analyzed in the effluent from April 1995 to April 2000 and the receiving water(location R-1) from July 1993 to June 1998. The results of these analyses were evaluated for their reasonable potential to exceed Basin Plan and CTR criteria. Section 1.3 of the SIP establishes the guidance for reasonable potential analysis. Table 11-1 summarizes the reasonable potential analysis of the detected inorganic, human health, and bioaccumulative constituents. From this analysis, the inorganic pollutants copper and cyanide were found to have a reasonable potential to cause or contribute to the exceedance of the applicable aquatic life priority pollutant criteria. There were twelve (12) human carcinogenic compounds present in either the RWCF effluent or in the ambient receiving water. As summarized in Table 11-1, eight (8) of the twelve (12) constituents were determined by the SIP process to present reasonable potential to exceed a one-in-a-million incremental human cancer risk criteria for water and/or organism consumption. In addition, three (3) of the eight (8) constituents listed in Table 11-1, dichloromethane, PCE, and TCE, were shown to have reasonable potential as a result of detectable concentrations in the background receiving water, monitoring location R-1, which exceeded CTR criteria. As discussed in the previous section, mercury, dioxin/f trans, PCBs, and Group A organo- chlorine pesticides, are California 303(d) listed pollutants causing impairment in Delta waterways. As required in Step 7 of Section 1.3 of the SIP, if a special condition exists (i.e., 303(d) listing for a pollutant) a reasonable potential to exceed water quality criteria is automatic. 11.3 Inorganic Prioritv Pollutants 11.3.1 Inoreanic Priority Pollutant Effluent Limitation Calculations Based on the information received to date from the Discharger, only the use of a steady-state model for calculating effluent limitations in the SIP can be justified at this time. Also, in the