2018-09-07_REVISION - C1981010 (2)

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Trapper Response to Comment 6A: New permit narrative pages 2-462n, 2-520xx, 2-523z and 2-524h are enclosed to address the ground water issues outlined above specific to proposed N Pit. Table of Contents page i-5 is revised and enclosed to reference these new pages. Rule: 2.04.7 (2) Hydrology Surface Water This is a review of the surface water related sections of the Hydrology Conditions and includes: a. Surface water flow rates. b. Water quality information. c. Waterbody locations and discharge into water bodies. The above rule is adequately addressed. However, DRMS possesses the following questions regarding TMI's newly issued NPDES discharge and monitoring requirements as per CDPHE. 6B. As some discussion is included regarding past NPDES permits, would it be appropriate to discuss on revised page 4-241a the recent changes to monitoring and analyte sampling put in place by CDPHE in 2018? Trapper Response to Comment 6B: We received a draft NPDES permit renewal from WQCD on March 8, 2018. We responded with 50 pages of questions and concerns. Agreement on a final renewal is still far from being finalized. Thus, discussion on page 4-241 a concerning changes to monitoring and analyte sampling is premature at this time. 6C. Please describe N Pit dewatering regime: i. State where this water will be routed. ii. Also, please describe the routing measures to be employed, illustrating routing locations and mechanisms with ditch designs, pumping regime and specifications where appropriate. Trapper Response to Comment 60 N Pit dewatering may occur after the initial boxcut is opened. Currently water may be discharged through outfall 011, East Pyeatt Gulch, and when the draft NPDES permit renewal is approved Trapper may discharge through outfall 009, Middle Pyeatt Gulch, as proposed to CDPHE. Water will most likely be routed from the pit or dewatering wells via HDPE pipelines laid on the ground surface. If any surface diversions are constructed they will be temporary in nature and designed and built using the temporary ditch designs in section 4.8.1.2 of the permit. If larger structures are required they will be evaluated at a later date and a revision submitted accordingly. Pit dewatering operations are typically temporary in nature and are currently being used in a similar fashion in the L Pit area. Further discussion and design inclusion to the permit is unwarranted at this time. DRMS notes that Grouse and Sage drainages have no current monitoring requirements.