2013-10-08_REVISION - M2012032 (13)

Home Browse Search

ground at the edge of the pond perimeter. The valve controls are shown on the cross - sections on Map G -12. The three gathering pipe valve stems are only 2.5 feet high and the dewatering pipe stem is only 3.5 feet high. 20. Please provide more information about the structures or materials to be used for the emergency spillway channel and the clean water spillway (as named on Map G -10). How will they be set into the surface, so that undercutting or erosion may be avoided? There is not an emergency spillway for the mine water pond. The spillway has been designed to be constructed of grouted riprap. The polypropylene lining the pond will be grouted into the grouted riprap spillway to prevent undercutting. The spillway hydrology designs are located in Appendix 12 - Mine Water Pond Hydrology. 21. It appears that there may be missing text after page 5 in this appendix. If so, please provide it. All pages will be submitted. 22. Besides the two pipes conveying water from the Revenue portal to the leach field, there will be two perforated pipes ( "weep lines') installed along the toe of the natural hill slope, as shown on the revised Exhibit C maps. All four of these pipes can be controlled by valves installed at the portal, but there is no indication as to the amount of use the "unfiltered" perforated pipes will have, as opposed to the pipes that lead to the lined impoundment structures. Please state whether the use of the weep lines is to be secondary to the other pipes, or used equally on a regular basis, or used primarily to allow inspection or repair of the lined structures. These pipes will be used as a secondary option and depends on the future water analysis of the mine water. These pipes (aka weep lines) will only be used after approval from CDPHE and DRMS. 23. Is the western perforated pipe that leads toward Atlas drainage capped on the end, or open to drain into collector ditch #3? Does the eastern perforated pipe pass under traffic ways, and if so, how is it protected? The ends of the pipes will be capped. The eastern pipe was deleted due to space constraints. 24. Under what conditions will the valves at the portal be opened or closed, and /or on what schedule, and by whom? The flow of water to the weep lines will be controlled to ensure that the mine water remains groundwater and does not surface to Sneffels Creek. All remaining mine water will be equally distributed between the two HDPE pipes that go to the leach field. The valves will be controlled by mine personnel. 25. The additional waste rock storage area at the east end of the permit area is a suitable location. It is known to be on a solid bedrock bench well above the elevation of the creek, and the drawing shows it to be sufficiently set back from the creek. The bedrock Ce