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<br />B. MONITORING REQUIREMENTS <br />9. Toxicity Incident Closure <br /> <br />Part I <br />Page lg of 19 <br />Permit No. CO-0036684 <br />If WET is controlled through implementation of numeric limits for <br />specific toxicants, through a control program eliminating toxicants <br />from the waste stream, or through the implementation of treatment <br />processes, or if WET disappears and Division required accelerated <br />testing demonstrate the continued absence of toxicity, the toxicity <br />incident shall be considered closed. <br />If the permittee completes all required phases of the toxicity <br />incident response specified in compliance schedules, and is unable <br />either to identify the causative toxicants and their sources or to <br />identify feasible treatment options, the permittee may petition the <br />Division far relief Erom further investigation and testing, consistent <br />with the permit regulations. <br />10. Frequency and Sample Type - Chronic WET Testing <br />The monitoring frequency for chronic toxicity tests shall be once <br />every six months on a January - June, July - December sequence, and <br />cannot coincide with acute testing. The first such test must be <br />completed and reported on the December DMR due January 28. Chronic <br />tests will be static replacement tests using three composite effluent <br />samples, each of which is to be composited for a minimum of eight <br />hours. Chronic testing will be conducted with both Ceriodaphnia sp. <br />and fathead minnows during the first year. During years two and <br />three, if requested in writing by the petmittee, the Divsion may grant <br />relief Erom continued two species testing. Such relief shall be for <br />continued testing with only that species which has demonstrated the <br />greatest sensitivity during the first year of testing. The results <br />shall be submitted on the Chronic Toxicity Test report form, available <br />from the Division. Copies of these reports are to be submitted to <br />both [he Division and EPA. <br />After May 30, 1994, the chronic testing requirements will no longer be <br />required unless applicable regulations require inclusion of a chronic <br />toxicity limit. <br />The permittee shall conduct each chronic toxicity test in general <br />accordance with methods described in the Division guidance document <br />entitled Guidelines for Conducting Whole Effluent Toxicity Tests. <br />As general information, chronic toxicity occurs when there is a <br />statistically significant difference in survival, growth or <br />reproduction for either species. <br />Revised 5/2/89 <br />Doc 1003M <br />