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PARTI Page 5 Permit No. CO-0027146 A. TERMS AND CONDTI'IONS 2. Burden of Proof Requirements (continued) b. For snowmelt, to waive TSS and total iron limitations, it is necessary to demonstrate that dischazge occurred within 48 hours after pond inflow has stopped. To waive settleable solids limitations, it is necessary to prove that dischazge occurred within 48 hours after pond inflow volume greater than the l0-yeaz, 24-hour event has stopped. Should a precipitation event or snowmelt occur, the permittee shall submit adequate proof in order for an exemption to be claimed. Weather station data may be appropriate in making this demonstration. Additionally, the permittee shall certify that the pond system was properly operated and maintained prior to and during the discharge. Said proof shall be submitted as an attachment to the Dischazge Monitoring Report (DMR) for the appropriate period. The Division shall determine the adequacy of proof. As part of this determination, the Division shall evaluate whether the permittee could have controlled the dischazge in such a manner that primary limitations could have been met. All manual dewatering of ponds that aze equipped with automatic dewatering systems must meet TSS and total iron limitations (where they apply). If a pond has only manual dewatering capability, relief is available only to the extent regtired to regain necessary stability and capacity. 3. Post-Minin re c Commencing at the time active mining has ceased and surface azeas have been retorted to the required contour and revegetation has begun, applicable dischazges may be eligible for limitations other than those specified in Parts 1.A.l.a. and b. These post-mining limitations shall remain in effect until bond release. The permit[ee shall notify the Division at the appropriate time so [hat consideration of permit modifications can be made. 4. Whole Effluent Toxicity Testing Requirements (Acute) - Outfalls 001. 002. 004 and 015 a. T~,[~n and Re ol> n'tIZ Reouiremems Tests shall be done at the frequency listed in Part I.B.1. Test results shall be reported along with the Dischazge Monitoring Report (DMR) submitted for the reporting period during which the sample was taken. (i.e., WET testing results for the first calendaz quaver ending Mazch 31 shall be repotted with the DMR due April 28.) The results shall be submitted on the Acute Toxicity Test report form, available from the Division. Copies of these reports aze to be submitted to both the Division and EPA along with the DMR. The permittee shall conduct an acute 48-hour WET test using Ceriodaphnia sp., and an acute 96-hour WET test using fathead minnows. Acute tests will be replacement static tests of a single effluent grab sample. The permittee shall conduct each acute WET test in general accordance with methods described in Methods for Measurine the Acute Toxiciry_Qf Effluents and Receiving Waters to Freshwater and Marine Org i ms, EPA/600/4-90/027 or the most current edition, except as modified by the most current Division guidance dotvment entitled Guidelines for Conductive Whole Effluent Toxicity Tesrc. b. Failure of Test and Division Notification An acute WET test is failed whenever the LC~o, which represents an estimate of the effluent concentration which is lethal to 509 of the test organisms in die time period prescribed by the test, is found to be less than or equal to 1009 effluent. The permittee must provide written notification of the failure of a WET test to the Division, along with a statement as to whedter the Preliminary Toxicity Incident ('PTI")/Toxicity Identification Evaluation ("TIE") investigation or accelerated testing is being performed (see next section). Notification must be received by the Division within 14 calendar days of the demonstration of acute WET in the routine required test. "Demonstration" for the purposes of Parts I.A.4.b., c., d. and f. means no later than the last day of the laboratory test. c. Automatic Comoliance Schedule Upon Failure of Test If a routine acute WET test is failed, the following automatic compliance schedule shall apply. As part of this the permittee shall choose one of the following courses of action.