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,k 7 COLORADO <br /> ," �y;! Department of Public <br /> Health&Environment Water Quality Control Division Fact Sheet,Permit No. C00048939 <br /> j. Dust Generation and Vehicle Tracking of Industrial Materials - In addition to other stormwater <br /> pollutants, the permittee must minimize generation of dust and off-site tracking of raw, final, or waste <br /> materials. <br /> IX. TERMS AND CONDITIONS <br /> A. Specific Monitoring Requirements <br /> Benchmark Monitoring: This renewal permit contains the requirement to conduct benchmark monitoring as <br /> an indicator of the performance of the measures undertaken to meet the stormwater effluent limitations <br /> contained in the permit. This approach is consistent with the benchmark monitoring requirement in the <br /> recently issued CDPS non-extractive industrial stormwater general permit (permit COR900000). <br /> The specific benchmark parameters and concentrations shown below, are consistent with those identified <br /> in the 2015 EPA Multi-Sector General Permit (Sector G: Metal Mining). The benchmark concentrations are <br /> not effluent limits. Therefore, an exceedance of the benchmark four-quarter average is not a violation of <br /> the permit, provided that no separate water quality exceedance resulted from the associated stormwater <br /> discharges. <br /> Parameter Units Benchmark Values Monitoring Sample <br /> Frequency Type <br /> Total Suspended Solids (TSS) mg/L 100 Quarterly Grab <br /> Turbidity NTU 50 Quarterly Grab <br /> pH s.u. 6.0-9.0 Quarterly Grab <br /> Total Arsenic pg/L 150 Quarterly Grab <br /> Total Cadmium pg/L 2.9 Quarterly Grab <br /> Total Copper pg/L 18.9 Quarterly Grab <br /> Total Iron pg/L 1000 Quarterly Grab <br /> Total Lead pg/L 122 Quarterly Grab <br /> Total Mercury pg/L 1.4 Quarterly Grab <br /> Total Nickel pg/L 610 Quarterly Grab <br /> Total Selenium pg/L 5 Quarterly Grab <br /> Total Silver pg/L 6.5 Quarterly Grab <br /> Total Zinc pg/L 160 Quarterly Grab <br /> Benchmark Monitoring Schedule: The renewal permit requires that the permittee conduct benchmark <br /> monitoring quarterly for the first four (4)full quarters of permit coverage. <br /> Benchmark Monitoring Actions: <br /> Data not exceeding benchmarks: Benchmark monitoring frequency can be reduced if the permittee can <br /> demonstrate monitoring values below the benchmarks concentrations. If, after collecting 4 benchmark <br /> samples, the average of the monitoring values for any parameter does not exceed the benchmark, the <br /> permittee may submit a request to the division to reduce benchmark monitoring frequency to once-per- <br /> year, rotating through the quarterly monitoring periods such that eight (8) samples are collected every five <br /> years. This monitoring framework allows samples to capture seasonal variations in stormwater discharges, <br /> yet relieves the permittee from quarterly sampling for the entire permit term, unless the benchmarks are <br /> exceeded (see below). <br /> Page 12 of 17 <br /> 4300 Cherry Creek Drive S.,Denver,CO 80246-1530 P 303-692-2000 www.colorado.gov/cdphe/wqcd * n <br /> John W.Hickenlooper,Governor Larry Wolk,MD,MSPH, Executive Director and Chief Medical Officer CO <br />