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WASTE DISCHARGE REQUIRRENTS ORDER NO.R5-2002-XXXX 7 MARLEY COOLING TOWER COMPANY SAN JOAQUIN COUNTY On 10 September 2001, the Executive Officer issued a letter, in conformance with Section 13267 of the California Water Code,requiring the Discharger to prepare a technical report assessing effluent and receiving water quality. A copy of that letter, including its Attachments I through IV, are incorporated into this Order as Attachment E. This Order includes a Provision which is intended to be consistent with the requirements of Attachment E in requiring sampling and reporting of NTR, CTR, and additional constituents to determine if the discharge has a reasonable potential to cause or contribute to an in-stream excursion above a water quality standard. 18. Sufficient effluent and receiving water flow data are available to determine that several constituents are or maybe discharged at a level that will cause or have the reasonable potential to cause, or contribute to an in-stream excursion above a narrative or numeric water quality standard. These constituents and/or parameters include; copper,hexavalent chromium, total chromium, arsenic, total dissolved solids (TDS), chlorine residual, and toxicity. Effluent limitations have been established or retained for these constituents as discussed in the following Findings of this Order. 19. Previous Order No. 93-221 included daily maximum and monthly average effluent limitations for copper based upon water quality objectives established by the California Inland Surface Waters Plan. Order No. 93-221 included a daily maximum limitation for copper of 6.5 micrograms per Liter(µg/L) or parts per billion (ppb), and a monthly average limitation for copper of 6.5 µg/L (ppb), which were adjusted based upon the observed receiving water hardness. New effluent limitations for copper have been established in this new Order based upon the reasonable potential to exceed freshwater aquatic life criteria in the CTR (new information). These new water quality based effluent limitations have been calculated based upon methodologies in the SIP. The specific calculations are further described in the attached Information Sheet. Results of final effluent monitoring indicate maximum effluent concentrations (MEC's) of total copper concentrations as high as 23 pg/L (ppb) (8/15/01) and 80 µg/L (ppb) (10/19/01). Without regard to dilution, these MEC's exceed the acute aquatic life Criterion Maximum Concentration (CMC) and the chronic aquatic life Continuous Criterion Concentration (CCC) for copper(total), adjusted using the minimum observed receiving water hardness (6.5 gg/L(ppb) and 4.6 µg/L (ppb) respectively @ 44 mg/L (ppm)hardness as CaCO3(12/20/01)). Since the Stockton Diverting Canal provides, at times, little or no dilution,there is a reasonable potential for the discharge to cause or contribute to an excursion above water quality standards. Section 1.3 of the SIP requires a water quality based effluent limitation when the MEC exceeds appropriate pollutant criterion. When required, Section 1.4 of the SIP provides four methods that may be used to develop effluent limitations. These four methods include: (1) assigning a loading allocation based upon a completed TMDL; (2) use of a steady state model; (3) use of a dynamic model; or, (4) establishing effluent limitations that consider intake water pollutants. Considering that the Stockton Diverting Canal may at times provide little or no assimilative capacity for copper, final water quality based effluent limitations have been developed using the steady state model, with