2022-02-09_PERMIT FILE - M2021046 (7)

Home Browse Search

2.7.6 Water Requirements The proposed mine facilities will require water for 1) drinking water purposes, 2)fire protection, 3) crushing, grinding and gravity separation processes, 4) rougher, clear flotation and regrinding processes, 5)tailings thickening and filtering, 6)gold concentrate thickening and filtering and 7) dust control. During development,there will be minimal water demand, but during operations,the mine facilities will require approximately 130 gallons per minute when in operation. Water will be provided by the mine dewatering, water recycling and a groundwater well. The mine is proposed to operate 365 days per year and annual demands are estimated at approximately 200 acre-feet during operation. As noted, a significant portion, approximately 90%, of this water demand will be provided by the reuse of water supplies within the mining process so once the reclaim water,filtered water and potable water tanks are full,they will only need to be topped off periodically.This water recycling system reduces the water demand to approximately 20 acre-feet per year. Dust suppression water will be provided using a truck with spreader bars using approximately 1.0 acre- feet per year. During reclamation,there will be minimal water requirements at the property. 2.7.7 Water Supplies The water supplies available to the property include 1)water dewatered from the mine and 2) a new water supply well to be constructed on the property. Recycling of the water used for mine processing also provides a significant supply of the water used in the processes. The new water supply well will provide water during the development stage. During mine operation,the water supply well and the dewatering of the mine will provide water to meet water demand. During mine operation,the process will mainly rely on the recycling of water with the water supply well used to top of the potable supply and the reclaim process water tank. The mine dewatering will only be used to top of the reclaim process water tank. An augmentation plan will be required to address the replacement of lagged stream depletions associated with the dewatering of the mine and the use of a new water supply well at the site. A portion of the dewatering water will return to the ground water system through infiltration of the discharge water. A portion will also be consumed in the potable system and the ore processing. It is feasible to project lagged stream depletions from the proposed mine operations and to identify supplies to replace those lagged stream depletion using both the return flows form the site and additional offsite supplies. As indicated above, Grape Creek will be identified as a point of depletion for augmentation purposes, but actual impacts are unlikely due the fractured rock geology at the site.The mine operator will implement the augmentation plan, including the acquisition and dedication of any necessary water rights to operate the plan.The augmentation plan will protect senior water rights from injury resulting from depletions to the surface water system. 2.7.8 National Pollutant Discharge Elimination System (NPDES) Permit Although the drainages at the mine are typically dry and best practices will be used to control sediment and discharges from the property including diversion channels, drainage ditches, culverts, sediment barriers and sediment ponds, a National Pollutant Discharge Elimination System (NPDES) Permit will be required in case discharges are made and the drainages do flow. Zephyr will acquire a NPDES permit 45