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Kimberley A. Wolf. Draft Permit Comments Colowyo Coal Co - Colowyo Coal Mine. CDPS CO-0045161 Page S. b. We have found that contact time is important, since oxidation is needed to significantly increase the concentration of iron in a discharge. This is our position for requiring WET testing for discharges from pits, we believe the likelihood for extended contact with the coal seam exists for water pumped from pits since it is likely to remain in a pit until the operator needs to remove it to facilitate mining; c. Surface runoff discharges are expected to occur when stream flows are high and instream quality is deteriorated by non-point source pollution and other sources. Also, we would expect temperatures of surface runoff (especially snowmelt) to be typically lower than the temperature of pit water. This would slow oxidation. It would be unreasonable to require permittees to construct treatment facilities to enable them to assure compliance with WET limitations, if this became necessary, since the flow volumes are unpredictable and sometimes quite large. This may seem contradictory to the First tow points, however the Division believes that the potential for toxicity in surface runoff from coal stockpile areas is low. If we receive information in the future that disputes this position, we can reopen permits as necessary to add WET requirements. 2. This comment has been addressed previously in this letter. 3. We acknowledge your plan to install effluent flow measuring devices. Your timetable should comply with the provisions of the individual permit. 4. We acknowledge your suggestion for permit language pertaining to relief for discharges containing pit pumped water. Assigning internal discharge points and requiring monitoring of pit water prior to being pumped to a pond should satisfy the question of which source was responsible for the exceedence. We will incorporate your comment into the Burden of Proof Requirements section of the pettnit. Your second recommended change to the language is no longer applicable because of the pond configuration changes. 5. Essentially, we agree with your comment. Please refer to our response to number 2. on page 4. of this letter for elaboration. 6. The general subject of this comment also is moot due to pond configuration changes. The Division has established an unwritten policy of considering any water, whether its initial source is precipitation, groundwater or any other possible source, once it comes into contact with an active industrial operation such as mining to be moved into the classification of "process water". This is a general classification used to differentiate from stormwa[er, which is generally understood to be precipitation-sourced water that has no[ contacted, to a substantial degree, an active industrial operation. Process water must typically be assessed to a greater degree to determine permit conditions necessary to assure compliance with surface water standards and use classifications. From this general classification of process water has evolved the Division's consideration of pit pumped water to be similar to underground mine water (or drainage). We have applied this consistently with coal mining permits and no other permittee to date has contested this categorization. The second patt of this comment addresses differentiation between pit pumped water and surface runoff for assessing qualification for relief for the "b" outfalls. We have previously stated our concurrence with your suggestion for how to handle this.