Laserfiche WebLink
RESPONSE TO WRITTEN COMMENTS -31- <br /> City Of Stockton-Regional Wastewater Control Facility <br /> NPDES No. CA0079138 <br /> 26 April 2002 Board Meeting <br /> years from the adoption date of the new criteria. As a result, a time schedule for compliance with the <br /> new corresponding effluent limitation is allowable. In addition to the interim numeric limitation, <br /> Provisions G.6 and G.7 require the Discharger to perform a pollution prevention plan and treatment <br /> feasibilitystudy. <br /> DeltaKeener Comment No. 6B: Copper: The interim copper limit is above the CCC and is <br /> virtually the same as the CMC. Staff used unreasonably high hardness values in computing the copper <br /> limit. We believe a hardness limit of 14 mg/I (interim limit) or 10.4 (final limit) likely violates <br /> Receiving Water Limitation No. 13. The copper limit fails to consider that a) copper and zinc are <br /> additive in toxicity and b) copper toxicity increases with elevated temperatures and 3) copper toxicity <br /> increases in the presence of low dissolved oxygen levels. Zinc, elevated temperature and low <br /> dissolved oxygen all may be occurring in the San Joaquin River at the same time. <br /> RWQCB Response: The interim effluent limitation for copper has been calculated in accordance <br /> with Section 2.1 of the SIP. Interim effluent limitations are intended to be performance-based rather <br /> than meet water quality objectives. In addition to the interim numeric limitation, Provisions G.6 and <br /> G.7 require the Discharger to perform a pollution prevention plan and treatment feasibility study. <br /> Furthermore, Provision G.1 requires the Discharger to operate the existing effluent dissolved air <br /> flotation and filtration facilities at all times by I January 2003. <br /> DeltaKeeoer Comment No. 6C: Total Dissolved Solids: Finding No. 36 states that the RWCF <br /> outfall is downstream of the impaired area of TDS and therefore the order does not include effluent <br /> limits to control TDS. Effluent data show that the annual average TDS concentration in the discharge <br /> (726 mg/1) exceeds the secondary Drinking Water MCL for TDS of 500 mg/I (as a recommended <br /> level) and the agricultural water quality goal of 450 mg/l. Yet, inexplicably, we could find no <br /> reasonable potential analysis as required by the federal regulations. A reasonable potential analysis <br /> must be conducted since ambient concentrations of TDS exceeded applicable criteria(as high as 630 <br /> mg/1). If staff disagrees, please explain. <br /> Reverse flows caused by state and federal project pumping are a common occurrence. Given multiple <br /> dosing because of tidal flow and reversed flows due to water exports, it is likely that TDS loads <br /> discharged at Stockton are drawn into the impaired waters of Old River. Future construction and <br /> operation of the barriers at Old River are problematic given the high likelihood of redirected impacts. <br /> The Permit must contain a limit for TDS. <br /> RWQCB Response: Finding 36 adequately documents the reasons for requiring a pollution <br /> prevention plan for TDS. <br /> DeltaKeever Comment No. 6D: CBOD and BOD: Staff seems confused in believing that <br /> CBOD plus ammonia comprises the extent of oxygen demand. This apparently stems from allowing <br /> the Discharger to switch from BODS to CBOD in the last permit. BODS equals CBOD plus nitrogen. <br /> However nitro yen is mors tha t ammonia. Nitrogen is comprised of ammor 1 r lus organic <br /> nitrogen. IS ion's disctiar - . :.ains considerable amounts of organic nitrog: In proposing <br />