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Probable Hydrologic Cousequences With the 1996 Annual Report, the operator has reorganized the Probable Hydrologic Consequences (PHC) section of the permit application. This reorganization was a result of the OSM 1996 Special Focus Inspection. Rule 2.05.6(3xb)(iii) requires that the permit application address the potential impacts to the hydrologic regime from mining. These impacts rteed to be discussed for the period while mining is taking place and when the entire site has been reclaimed. The submittal, dated April ] 7, 1997, discusses only predicted impacts after mining has ceased. Therefore, the following question needs to be resolved. 15. Please add a discussion in the PHC concerning anticipated impacts to the hydrologic regime, as required in section 2.05.6(3)(b)(iii) of the Rules, for the time that mining is taking place. Surface Water The PHC section concerning surface water quantity predictions, on page 4-237 of the April 17, 1997 submittal, does not contain any attempt at quantifying future runoff predictions. The Division agrees that such a quantification is difficult, but, may be possible in the general sense using hydrologic modeling techniques that use curve numbers for runoff. Therefore, the Division poses question no. 16. 16. Please add a discussion on page 4-237 of the April 17, 1997 submittal, that attempts to quantify the surface runoff predictions for the period during mining and after mining. The April 17, 1997 PHC predicts that the postmine surface water quality will show elevated levels of TSS, but that the sediment ponds will prevent such elevated TSS levels from going offsite. No discussion is presented for the postmine situation after the sediment ponds are removed. Therefore, question no. 17 is posed. 17. Please add a discussion, on page 4-237 of the April 17, 1997 PHC submittal, that predicts the general TSS levels leaving the mine site after the sediment ponds aze reclaimed. The PHC predicts that total iron and manganese levels will continue to be high intermittently after mining. Also, it is anticipated that the pH levels after mining ceases will be about the same as they have been and aze now. Finally, TDS levels are expected to rise for a few years after mining, then fall back to premise levels. Nothing in the 1996 Annual Report data seems to contradict these predictions. Concerning the Yampa River, the PHC correctly states that most of the flow off of the mine site does not make it to the river. Therefore, no discernible impacts to the Yampa River from mining operations are anticipated. One hydrologic issue fromTechnical Revision No. 66 that remains to be fully resolved is the issue of full suite water quality sampling of surface water runoff from a disturbed area, even