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10-year, 24-hour event. Now assume the pond self-discharges (rather than is dewatered manually). It is our understanding that the alternative limitations described on page 3 of the Permit (Part I.A.I.a.) could apply. Now assume a scenario where the same type and volume of water enters a pond, but the precipitation event that created the runoff occurred over a 36-hour period, rather than a 24-hour period as described above. [t is our understanding that when the pond self discharges under this second scenario, alternate effluent limitations, rather than primary limitations, would apply. Is this correct'? 13. Assume a new scenario in which five consecutive non-overlapping 24-hour periods elapse. Assume during each of these 24-hour periods, a 6-year, 24-hour event occurs, Assume now that Colowyo elects to manually open a pond's dewatering valve during the fourth non-overlapping 24-hour period. As it is stated on page 5 of the permit that "Relief ...shall not be granted when the petTttittee has control over the discharges", we understand that the effluent coming from that pond's outfall must meet primary limitations. Is this correct? 13. Assume snowmelt is the sole source of water flowing into a pond. Assume this snowmelt occurred in a volume equivalent to that of a 8-year, 24-hour event. Now assume a sample of aself-discharge was not taken until 50 hours after pond inflow stopped. It is our understanding that this discharge must meet primary limitations. [s this correct? l4. Assume the same scenario above, but change the time for sampling the pond's self- discharge from 50 hours after pond inflow stopped to 45 hours after pond inflow stopped. If the discharge was sampled at 45 hours after pond inflow stopped, we assume the discharge would be eligible for relief from primary limitations. Is this correct? I5. Now assume the same scenario in 13., but change the time of sampling from 50 hours to 24 hours after pond inflow had stopped. What part, if any, of this discharge is required to meet primary limitations, and what part, if any, of this discharge is eligible for relief from primary limitations? B. Summary of Rationale In the third paragraph of Page 4 (Part N.B.), it is stated that "The ponds are currently being operated in the "containment" mode, meaning that the volume from a storm event is contained for a prescribed period while settling occurs, after which time the discharge structure is manually opened and discharge to state waters occurs. The permittee is reevaluating all outfalls, using the Colorado Division of Minerals and Geology approved SEDCAD hydrology model, for potential conversion to the "treatment" mode, wherein discharge occurs automatically when the volume reaches a certain level."