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PART I <br />Page 7 of 22 <br />Permit No.: CO-0001244 <br />g. Toxicity Reopener <br />This permit may be reopened and modified (following proper administrative procedures) to include new compliance <br />dates, additional or modified numerical permit limitations, a new or different compliance schedule, a change in the whole <br />effluent toxicity testing protocol, or any other conditions related to the control of toxicants if one or more of the following <br />events occur: <br />i. Toxicity has been demonstrated in the effluent and the permit does not contain a toxicity limitation. <br />ii. The PTI/TIE results indicate that the identified toxicant(s) represent pollutant(s) that may be controlled with specific <br />numerical limits and the permit issuing authority agrees that the control of such toxicants through numerical limits is the <br />most appropriate course of action. <br />iii. The PTI/TIE reveals other unique conditions or characteristics, which, in the opinion of the permit issuing authority, <br />justify the incorporation of unanticipated special conditions in the permit. <br />C. DEFINITIONS OF TERMS <br />1. "Acute Toxicity" means there shall be no acute toxicity in the effluent from this discharge point. The acute toxicity limitation <br />is exceeded if 1) a statistically significant difference in mortality (at the 95% confidence level) is observed for either species <br />between the control and any dilution less than or equal to the identified IWC or 2) a species mortality in any dilution of <br />effluent (including 100% effluent) exceeds 50%. <br />2. Antidegradation limits apply as the average of all data collected for months in that group during a rolling 24-month period. <br />These limits become effective after data has been collected for all months in the group during the 24 months following permit <br />issuance. Where antidegradation groups are not indicated, data from all months will be utilized to determine the reported <br />value and the limit will become effective in the 24th month in which the permit is effective. <br />3. "Chronic lethality" occurs when a statistically significant difference, at the 95% confidence level, occurs in the chronic test <br />between the mortality of the test species in 100% effluent (the chronic IWC = 100%) and the control and when the lethality <br />IC25 is less than the IWC. <br />4. "Composite" sample is a minimum of four (4) grab samples collected at equally spaced two (2) hour intervals and <br />proportioned according to flow. <br />5. "Continuous" measurement, is a measurement obtained from an automatic recording device which continually measures <br />provides measurements. <br />6. "Daily Maximum limitation" for all parameters except temperature, means the limitation for this parameter shall be applied as <br />an instantaneous maximum (or, for pH or DO, instantaneous minimum) value. The instantaneous value is defined as the <br />analytical result of any individual sample. DMRs shall include the maximum (and/or minimum) of all instantaneous values <br />within the calendar month. Any instantaneous value beyond the noted daily maximum limitation for the indicated parameter <br />shall be considered a violation of this permit. <br />7. "Daily Maximum Temperature (DM)" is defined in the Basic Standards and Methodologies for Surface Water 1002-31, as <br />the highest two-hour average water temperature recorded during a given 24-hour period. This will be determined using a <br />rolling 2-hour maximum temperature. If data is collected every 15 minutes, a 2 hour maximum can be determined on every <br />data point after the initial 2 hours of collection. Note that the time periods that overlap days (Wednesday night to Thursday <br />morning) do not matter as the reported value on the DMR is the greatest of all the 2-hour averages. <br />For example data points collected at: <br />08:15, 08:30, 08:45, 09:00, 09:15, 09:30, 09:45, 10:00, would be averaged for a single 2 hour average data point <br />08:30, 08:45, 09:00, 09:15, 09:30, 09:45, 10:00, 10:15, would be averaged for a single 2 hour average data point <br />08:45, 09:00, 09:15, 09:30, 09:45, 10:00, 10:15, 10:30, would be averaged for a single 2 hour average data point <br />This would continue throughout the course of a calendar day. The highest of these 2 hour averages over a month would be <br />reported on the DMR as the daily maximum temperature. At the end/beginning of a month, the collected data should be used <br />for the month that contains the greatest number of minumtes in the 2-hour maximum.