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9. The mine plan specifies 1) an average 20 foot depth (8-10 ft. overburden and topsoil, 10-12 ft. <br />sand and gravel); 2) mining will be conducted in 20 foot lifts; and 3) gravel extraction will occur in <br />a single lift. Taken together, these statements are somewhat confusing. Please revise them to <br />clarify their meaning. It appears that mining will be conducted in a single 20 foot lift. Is that <br />correct? <br />10. Please specify liner material and construction specifications for spill containment structures. <br />11. The mine plan mentions intermittent operation. If periods of inactivity of 180 days or more are <br />anticipated, please revise the application to address the requirements of Rule 1.13.7 for <br />intermittent operation status. <br />12. Please describe where and how haul roads within the permit area will be constructed and how <br />they will change during the course of mining. <br />13. The underlying stratum is identified as shale. If Mancos shale, please describe measures to be <br />implemented to prevent exposing the shale to oxidization potentially increasing selenium loading <br />in the groundwater. <br />14. Please demonstrate that the existing Swale, to be used to carry the pit dewatering discharge to <br />the Colorado River, is adequately sized and stable to handle this flow rate and volume without <br />significant erosion and sediment discharge to the river. If the swale requires armoring, it will need <br />to be included into the proposed affected area through the amendment to an application' process <br />detailed in Rule 1.8. <br />15. Please demonstrate that the culvert pipe under Interstate 70, slated to carry the pit dewatering <br />discharge, is adequately sized and designed to carry it's designated capacity plus the additional <br />discharge from the pit. Consent from the Colorado Department of Transportation may also be <br />required to use their structure for this use. <br />16. Please specify maximum disturbed area at any one time during the mining operation per Rule <br />6.4.4(d). Please break these figures down by area, ie: office/plant area, internal roads, active pit <br />area, and pit in various stages of reclamation. <br />17. It appears that the proposed stockpiles will hold less than 15 percent of the total overburden, <br />which is approximately 17 percent of the amount required for reclamation of the site. Therefore, it <br />appears that direct hauling of overburden from active mining areas to active backfilling areas will <br />be required. Please detail the anticipated earthmoving for each phase as required by Rule <br />6.4.4(b). <br />18. Please provide a timetable that includes the required information specified in Rule 6.4.4(e) <br />19. Please describe how inflow into the pit will be managed through to the discharge location. <br />20. Please demonstrate how operations will be managed and what monitoring program will be <br />conducted to ensure groundwater levels do not fluctuate more than two feet at the location of <br />large trees on land adjacent to the proposed permit area. <br />21. Page D-2 indicates that a sediment pond will be constructed prior to mining below the water table. <br />Please revise this wording to indicate the sediment pond will be constructed prior to discharge of <br />water from the site. <br />