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o a <br />COLORADO DEPARTMENT OF HEALTH <br />Water Quality Control Division <br />Rationale - Page 10 <br />Permit No. CO-0027154 <br />Outfall 007 <br />Table 8 ehowe the limitations, rationale and monitoring frequencies for this <br />outfall. <br />TABLE 8 <br />Monitoring <br />Parameter Limitation Rarionale Frequencies <br />Flow, MGD N/A Monitoring Weekly <br />pH, s.u. 6.5 - 9.0 a/ WQS Weekly <br />011 and Grease, mg/1 10 a/ SES Weekly <br />Total Suspended Solids, mg/1 35170 b/ SES Weekly <br />Total Recoverable Copper, mg/1 0.01/0.02 b/ WQS Weekly <br />Total Recoverable Manganese, mg/1 1.0/2.0 b/ WQS Weekly <br />Dissolved Manganese, mg/1 0.05/0.10 b/ WQS Weekly <br />Total Recoverable Zinc, mg/1 0.05/0.10 b/ WQS Weekly <br />Total Recoverable Iron, mg/1 1.0/2.0 b/ WQS Weekly <br />Total Dissolved Solids; mg/1 5000 r-~- WQS Weekly <br />Settleable Solids, ml/1 0.5 c/ BAT Weekly <br />a/ Limitations effective at all times <br />b/ 30-day average/daily maximum respectively <br />Limitations effective at all times, except TSS (See c/) <br />c/ Limitation may apply to discharges caused by precipitation less than or equal <br />to the 10-year, 24-hour precipitation event is place of TSS limitations. <br />DISCUSSION: <br />A. Total Suspended Solids - E.P.A. promulgated SAT regulations on November <br />26, 1982, but BCT (Best Conventional Pollutant Control Technology) is <br />being reserved pending finalization of EPA's BCT cost methodology. <br />Therefore, BPT shall apply. The SES limitation is not applicable pursuant <br />to Section 10.1.3(3) of the State. Regulations for Effluent Limitations, <br />which states that when EPA has effluent limitations for an industry, the <br />federal limitations shall take precedence. <br />B. Monitoring and Reporting - Monitoring requirements for those outfalls <br />discharging only surface runoff are adequate to determine the impact <br />resulting from such infrequent discharges. Monitoring at outfalls 005 and <br />007 shall be weekly for all parameters. The permittee is already <br />monitoring at 11005 this frequently. Initial monitoring of 11007 shows <br />large variations in the quality and quantity of the discharge. Thus, <br />frequent monitoring is justified. <br />Previously, reporting has been on a quarterly basis. This renewal will <br />require monthly reporting. This is a large facility which is classified <br />as a major by EPA. Thin necessitates monthly reporting. <br />