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Finally, the hardness level used to apply the criteria (1 10 mg/1) is not reflective of <br /> expected conditions or more recent test results. Effluent data in 1993-94 indicated a <br /> typical hardncss of 110 mg/1. More recent test results (1996 to present) show that effluent <br /> hardness in 11 of 13 test was 120 mg/I or greater. The lowest hardness readings were 110 <br /> mg/l and appear to be associated with Wet weather periods. Thus,.any analysis of metals <br /> should use a minimum hardness of 120 rrb/l or higher. <br /> Given the available information that dissolved zinc levels, before con.sidera[ion of <br /> dilution, arc below EPA's objectives and that zinc is not in a toxic form,there is no basis <br /> to conclude that stringent Zinc limitations are necessary at this time. Tf dilution were <br /> considered, there would be no basis for establishing a zinc limitation, even using the <br /> Regional Board's worst case assumptions. Until valid data is collected and reasonable <br /> translator coefficients can be detennined, the effluent limitation for zinc should be <br /> »toriitor only. A schedule of compliance in the permit to complete this study would he <br /> necessary and appropriate for conducting such monitoring. <br /> Lead <br /> The City objects to the monthly average effluent limitation for lead because the <br /> Regional Board based the limitation on a direct (end-of pipe) application of EPA's <br /> dissolved Fater quality criteria, without providing for dilution, but adjusting for hardness <br /> and converting to total recoverable metal. The available performance data do not show <br /> that dissolved lead is discharged or present in the receiving waters. (.See, lead data, Table <br /> 1 —Effluent Metals Testing Data.) Total recoverable metals levels have reached 9 ug/1 <br /> with no measured dissolved component, indicating a minimum translator of 8.5. Thus, <br /> the conservative translator approach used by staff to conclude dissolved lead levels in <br /> Dredger Cut exceed EPA criteria is clearly misplaced. <br /> As noted with zinc, the Regional Board staff failed to apply an appropriate <br /> dissolved-to-total translator to determine the effluent limitation as recommended by EPA. <br /> If the Regional Board had followed EPA's translation method, the correct monthly <br /> average total recoverable effluent limitation would have been at least four times the value <br /> included in the Permit. ,Cee, Translator Guidance at pp. 5 -10 (Attachment 2) and <br /> t ESPermitComm ms Exhibit 2 Page 7 1JJ17i99 <br />