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PART III <br />Page 48 of 48 <br />Permit No.: C00000906 <br />shipping and receiving areas; manufacturing buildings; storage areas (including tank farms) for raw materials, and <br />intermediate and final products; and areas where industrial activity has taken place in the past and significant <br />materials remain and are exposed to stormwater. See 5 CCR 1002-61.3(2)(e). <br />36. "Thirty (30) day average" means, except for fecal coliform or E. coli bacteria (see geometric mean), the arithmetic <br />mean of all samples collected during a thirty (30) consecutive -day period. The permittee shall report the <br />appropriate mean of all self-monitoring sample data collected during the calendar month on the Discharge <br />Monitoring Reports. Samples shall not be used for more than one (1) reporting period. (See the "Analytical and <br />Sampling Methods for Monitoring and Reporting Section in Part I.D.3 for guidance on calculating averages and <br />reporting analytical results that are less than the PQL). <br />37. "Total Maximum Daily Loads (TMDLs)" - A TMDL is a calculation of the maximum amount of a pollutant that a <br />waterbody can receive and still meet water quality standards, and an allocation of that amount to the pollutant's <br />sources. A TMDL includes wasteload allocations (WLAs) for point source discharges; load allocations (LAs) for <br />nonpoint sources and/or natural background, and must include a margin of safety (MOS) and account for seasonal <br />variations. (See section 303(d) of the Clean Water Act and 40 CFR 130.2 and 130.7). <br />38. "Total Metals" means the concentration of metals determined on an unfiltered sample following vigorous digestion <br />(Section 4.1.3), or the sum of the concentrations of metals in both the dissolved and suspended fractions, as <br />described in Manual of Methods for Chemical Analysis of Water and Wastes, U.S. Environmental Protection Agency, <br />March 1979, or its equivalent. <br />39. "Total Recoverable Metals" means that portion of a water and suspended sediment sample measured by the total <br />recoverable analytical procedure described in Methods for Chemical Analysis of Water and Wastes, U.S. <br />Environmental Protection Agency, March 1979 or its equivalent. <br />40. "Toxicity Identification Evaluation (TIE) " is a set of site-specific procedures used to identify the specific <br />chemical(s) causing effluent toxicity. <br />41. "Toxicity Reduction Evaluation (TRE)" is a site-specific study conducted in a step -wise process to identify the <br />causative agents of effluent toxicity, isolate the source of toxicity, evaluate the effectiveness of toxicity control <br />options, and then confirm the reduction in effluent toxicity after the control measures are put in place. <br />42. "Twenty four (24) hour composite" sample is a combination of at least eight (8) sample aliquots of at least 100 <br />milliliters, collected at equally spaced intervals during the operating hours of a facility over a twenty-four (24) <br />hour period. For volatile pollutants, aliquots must be combined in the laboratory immediately before analysis. <br />The composite must be flow proportional; either the time interval between each aliquot or the volume of each <br />aliquot must be proportional to either the wastewater or effluent flow at the time of sampling or the total <br />wastewater or effluent flow since the collection of the previous aliquot. Aliquots may be collected manually or <br />automatically. <br />43. "Twice Monthly" monitoring frequency means that two samples shall be collected each calendar month on separate <br />weeks with at least one full week between the two sample dates. Also, there shall be at least one full week <br />between the second sample of a month and the first sample of the following month. <br />44. "Visual" observation is observing the discharge to check for the presence of a visible sheen or floating oil. <br />45. "Water Quality Control Division" or "Division" means the state Water Quality Control Division as established in 25-8- <br />101 et al.) <br />46. "Water Quality Standards" - means a narrative and/or numeric restriction established by the Commission applied to <br />state surface waters to protect one or more beneficial uses of such waters. Whenever only numeric or only <br />narrative standards are intended, the wording shall specifically designate which is intended. See 5 CCR 1002- <br />31.5(37). <br />Additional relevant definitions are found in the Colorado Water Quality Control Act, CRS SS 25-8-101 et seq., the <br />Colorado Discharge Permit System Regulations, Regulation 61 (5 CCR 1002-61) and other applicable regulations. <br />