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<br />PART 2 <br />Page lk of 19 <br />Permit No. CO-000022 <br />B. MONITORING REQUIREMENTS <br />9. Control Program (Cont.) <br />A control program may include, but shall not be limited to: additional <br />pretreatment requirements imposed on specific indirect permitteee by POTW's, <br />modification of internal source control programs by industries, modifications of <br />treatment plants, and/or best management practices for spills, leaks, etc. <br />10. Toxicity Incident Closure <br />If WET is controlled through implementation of numeric limits for specific <br />toxicants, through a control program eliminating toxicants from the waste stream, <br />or through the implementation of treatment processes, or if WET disappears and <br />Division-required accelerated testing demonstrates the continued absence of <br />toxicity, the toxicity incident response shall be considered closed and normal <br />quarterly monitoring shall resume. <br />If the permittee completes all required phases of the toxicity incident response <br />specified in compliance schedules; and is unable either to identify the causative <br />toxicants and their sources or to identify feasible treatment options, the • <br />permittee may petition the Division for relief from further investigation and <br />testing, consistent with the permit regulations. <br />11. Freouencv and Sample Tvpe - Chronic WET Testing - 004, 60E <br />The monitoring frequency for chronic toxicity tests shall be once every six months <br />on a January - June, July - December sequence, and cannot coincide with acute <br />testing. Chronic tests will be static replacement tests using three composite <br />effluent samples, each of which is to be composited for a minimum of eight hours. <br />Chronic testing will be conducted with both Ceriodaohnia sp. and fathead minnows <br />during the first year. During years two and three, if requested in writing by the <br />permittee, the Division may grant relief from continued two species testing: Such <br />relief shall be for continued testing with only that species which has <br />demonstrated the greatest sensitivity during the first year of testing. The <br />results shall be submitted on the Chronic Toxicity Test report form, available <br />from the Division. Copies of these reports are to be submitted to both the <br />Division and EPA. <br />The permittee shall conduct each chronic toxicity test in general accordance with <br />methods described in the Division guidance document entitled Guidelines for <br />Conducting whole Effluent Toxicity Tests. <br />As general information, chronic toxicity occurs when there is a statistically <br />aigniflcant difference in survival, growth or reproduction for either species. <br /> <br />