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Daniel I. Hernandez, Colorado Division of Minerals and Geology Response to Comments on Draft Permit, Colowyo Coal Company, L.P. CDPS No. CO-0045161 (pending). Moffat County Page 2 11. In both the first and second scenarios, as in 5. above, the discharge would be eligible for exemption from primary limitations through 48 hours after [he event ended and the exemptible parameters would be TSS and total iron. After 48 hours, all discharges would have to meet [he primary limitations, It is important to note that the term "eligible" is used. The exemption is not automatic, a permittee needs to provide proof that primary limitations could not be met. The Division considers factors such as was [he pond properly operated and maintained prior to and during the discharge, in addition to the occurrence and size of a storm event, in determining eligibility-for the exemption. We have pointed out in previous correspondence to the perntittee that the primary goal is minimize the amount of sediment entering streams. We have no doubt that they recognize this 12. This scenario would be dependent upon whether the permittee in fact only has manual dewatering capability. If the pond would automatically dewater but the permittee chose to manually dewater instead of allowing the automatic system to work, then the discharge mus t meet primary limitations. If the pond has no approved automatic dewatering capability, then manual dewatering would be the only option and the discharge would be eligible for alternate limitations (but not automatically exempt from primary limitations). Factors such as described in 11. above would apply. 13. For this scenario, primary limitations do apply. 14. Yes, this discharge would be eligible for relief from primary limitations l5. This discharge, at the time of sampling, would also be eligible for relief from primary limitations. Any discharge lasting after 48 hours after inflow has stopped must meet primary limitations. These interpretations are based on alternate limitation burden of proof language developed by the Division several years ago. The language has been included in several coal mining CDPS permits including the previous and current CDPS General Permit For Coal Mining Facilities. B. Rationale 11. An "intermittent" discharge is considered by the Division as any discharge that ceases temporarily at any time. A discharge occurring for three days during the first month of a quarter is considered intermittent. As general information, we verbally instruct permittees with intermittent discharges that are expected to cease before the end of a monitoring period that they should sample when the discharge occurs. A permittee who knows that a pattern of intermittent discharge exists but routinely fails to sample when the discharge occurs could be cited for failure to monitor. We will evaluate your request that each manual discharge be sampled. In doing so, we will consider whether failure to impose this requirement would violate Part I.E.2. of the permit.