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Daniel 1. Hernandez, Colorado Division of Minerals and Geology <br />Response to Comments on Draft Permit, Colowyo Coal Company, L.P. <br />CDPS No. CO-0045161 (pending). Moffat County <br />Page 2. <br />This may seem contradictory [o the first two points, however the Division believes that the potential for <br />toxicity in surface runoff from coal stockpile areas is low. If we receive information in the future that <br />disputes this position, we can reopen permits as necessary [o add WET requirements. <br />2. (No response required) <br />All CDPS permits require effluent flow measuring devices that measure flow to within 10% of the actual <br />flow. Although we hesitate to require continuous recording devices at the influent side of sedimentation <br />ponds because of cost, we believe that such devices would be invaluable to permittees when claiming an <br />exemption from primary limitations by demonstrating that a specific volume entered a pond in a specific <br />time period. We are aware of no other method as foolproof as [his. <br />4. Your interpretation is correct as i[ relates to the draft permit which you have reviewed. Since the drafr was <br />written the permittee has suggested they monitor pit water prior to being pumped to a pond and that any <br />water that did not meet primary limitations would not be pumped. We have discussed this further with <br />Colowyo and come to an agreement that the Division will establish internal discharge points at the points <br />where pit water would be pumped. Total suspended solids will be limited to 35/70 mg/P and total <br />recoverable iron will be limited to 1.0 mg/Q at these points. The TR Iron limitation is set at a level [hat will <br />assure levels of iron that are nontoxic according to all reference material available to us. Additionally, this <br />is the water quality standard for the Yampa River below confluence with Colowyo's immediate receiving <br />waters. The discharge of vehicle wash water will be limited similarly and short-term monitoring will be <br />required of this water for BETX (benzene, ethylbenzene, toluene and xylene) to detect petroleum-related <br />constituents that may be present. If BETX is detected at or above the Division-developed limitation of 0.1 <br />mg/Q, the permit may be reopened to add limitations and/or other appropriate conditions. <br />Your assumption that neither vehicle wash water nor pit pumpage should be discharged through any <br />outfalls other than 002, 004, 007, 008, 009 and 010. Further, the additional label "b" will be specified at <br />the internal points where these sources would be sent to the appropriate ponds and numeric limitations will <br />be in effect. Table II-1 in the draft rationale specifies which sources are authorized from each outfall. <br />Because of this change, there will no longer be permit language that specifies that outfalls that are <br />composed most of vehicle wash water or pit pumpage are not eligible for relief from primary limitations. <br />The permittee will be provided with separate discharge monitoring reports that will be denoted with the "b" <br />label for these internal points to verify that they meet the limitations in Part I.A.I.b. of the permit. This is <br />a new approach suggested by the petmittee and elaborated on by the Division, and we believe it offers <br />more protection for the environment than that in the previous draft you reviewed. <br />5. As currently proposed in the draft permit, in your example this discharge would be eligible for exemption <br />from primary limitations beginning with the first discharge of this water through 48 hours after the event <br />ended and the exemptible parameters would be TSS and total iron. After 48 hours, all discharges would <br />have to meet the primary limitations. Colowyo has mentioned [he discrepancy between the applicable <br />periods for application of alternate limitations for rainfall vs. snowmelt; i.e., for rainfall the "clock" begins <br />when measurable precipitation ends and for snowmelt the "clock" begins when inflow to the pond stops. <br />This has been the Division policy regarding such discharges for several years and is consistent among all <br />current permits. We wil! not change it at this time in acknowledgment of all the permits in effect with this <br />language. <br />