2011-05-25_REVISION - C1981018 (2)

Home Browse Search

and take note that no facet of the wetlands was relied upon to demonstrate compliance with applicable standards. 10. Thank you for catching our mistake. Appropriate changes were made to page IV-37 and the revised page attached. 11. The Dewatering Ponds do not have `spillways' as they empty directly onto the natural grade from the in-situ configuration. But to meet the letter of the regulations we will bury a narrow strip of woven geotextile to form a `non-erodible' `single open-channel spillway' to satisfy the Division. Please see the cross section added to Map 157 to hopefully satisfy your concerns. The SedCAD runs have been revised to show a stable flow through the ponds using the 25-year, 24- hour event plus 100-gallons of discharge from the dewatering system. The 100-gallons per minute of discharge was created in the model by increasing the surface area of the ponds (curve number = 100) to increase the outflow by 0.22 CFS. The overland flow `channel' was modeled as bare soil. Vegetation will quickly establish creating a much more stable flow path. 100-gallons per minute is a high estimate of peak dewatering flows prior to vegetation establishment. Current flows are only 32.6 gpm in our existing system. 12. This is a Technical Revision to our-existing permit and not a stand-alone mine permit application. Our current permit addresses interim reclamation practices. Please see Section V of our permit. We have no intention of developing a separate plan for this facility. 13. BME is committed to comply with applicable regulations governing our operations. We are well aware of Rule 4.05.9(14) and the certifications process associated with it. BME currently has two PEs qualified to provide such certifications. Since these ponds are essentially in-situ with negligible to no head on `embankment' inspections during construction are simple with only limited firming needed of material for the `Last Chance' embankment. The main focus will be to ensure proper volumes are obtained, dewatering ponds are constructed on grade, the Last Chance flume is installed per manufacturer's specifications, the Last Chance emergency spillway is located at the proper elevation relative to the flume, and the outlet channel from the Last Chance flume properly installed. Quarterly inspections following construction will be consistent with current practices for our existing ponds. General overall observations will be undertaken more frequently initially to ensure the site remains stable and the system is functioning properly. 14. The soil stockpiles are located at the edge of the ponds to facilitate reclamation. Their locations are appropriate considering the facilities and desire to minimize surface disturbance and minimize reclamation liability. Furthermore, the ponds act to control and treat runoff from these piles and do not jeopardize the ponds or pile in any way. We intend to maintain the soil piles as originally shown. 15. We do not know with certainty how much of the water from the dewatering system will be lost to infiltration and how much will be available for wetland establishment. The establishment of wetland vegetation within this area is being left to the creativity and resources of BME. While we intend to supplement the site with locally collected wetland species we are not committing to details which are dictated by unknown conditions. Given the uncertainty of flows to the wetlands we will seed disturbances within the site with the interim seed mix per Section V of our mining permit. Wetland species we currently envision supplementing with include cattails, bulrushes, sedges, and possibly willows. It has been our observation that many of these species rapidly colonize areas with suitable moisture without added input from the operator. Western wheatgrass currently on site is capable of providing fast cover on fringe and overland flow areas.