2019-09-13_PERMIT FILE - M2018051 (11)

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Two lined ponds will support the processing facilities. One will contain process water from the sand wash processing plant and will be recycled to feed the process water tank.The second pond will be used for temporary storage of slurry from the sand wash processing plant, as necessary.The ponds will be located adjacent to each other, lined with HDPE liners, and will be constructed at grade. Both ponds will be approximately 0.5 acres in area,with a depth of no more than 10 feet.They will be capable of handling approximately 1.6 million gallons each. Safety berms will surround each pond. Construction and operations will be conducted with a Spill Prevention Control &Countermeasure (SPCC) Plan as well as Storm Water Pollution Prevention Plan (SWPPP). Please refer to Exhibit G for more water information. 6.4.4. (d)Size of Area -The processing facility(approximately 45 acres)will be in use the entire life of the operation.As shown on Map D1, Mining Plan Map,the mining area has been outlined to show the approximate yearly mining blocks for the first 10 years and the sequence of additional 10-year mining blocks over the mine's 35-year life. Each yearly block will be mined sequentially,with concurrent backfilling as operations progress.As a pit backfill is completed, it will be regraded and reclaimed in accordance with reclamation plans.At any given time, only one block will be actively mined. It is estimated each highwall will take approximately 3 years to regrade and reclaim. With the concurrent reclamation, it is not anticipated that the entire area of any block would be disturbed at any given time,since backfilling will occur simultaneously with active mining area of the pit. 6.4.4. (e)Approximate Timetable- For the purposes of discussion,this section is divided into 3 phases- construction, operations, and reclamation. Construction The construction stage will include the installation of all sand wash processing plant facilities,facility road installation and existing road upgrades, and installation of all utilities necessary for sand wash processing plant operations. See Figure D3,Site Plan,for details.This stage will also include the construction of the temporary sediment basin to be used for construction stormwater management.The construction stage is estimated to take approximately 8-12 months to complete. A Construction Stormwater General Permit will be obtained from CDPHE and a Stormwater Management Plan and associated Erosion Control Map will be prepared for the construction areas.Appropriate erosion control BM Ps will be installed at each area of the project where construction activities will occur prior to any land disturbing activities and will be maintained throughout the construction stage. Once construction activities are complete and all impervious surface areas are installed,temporary BMPs will be removed. No landscaping is currently planned.All stormwater runoff will be directed to the onsite temporary sediment basin;the facility will not be connected to an external sewer drain system. Facilities The processing facility area is approximately 45 acres and access will be located off WCR 91 at approximately 40° 14'49.00" N and 104°12'24.50"W. It will include approximately 2,800 linear feet(3.0 acres) of paved road and 1.3 acres of impervious surface for parking areas.The remainder of the facility will be used for constructed buildings and associated facilities or left as native vegetation buffer areas.The mine pits have been designed more than 200 feet from the edge of the facilities area boundary(buffer areas).This facilities buffer area will consist of undisturbed native vegetation areas that stormwater runoff will be directed to and/or discharged to from the settling pond, as needed. The sand wash processing plant will consist of a plant feed stockpile,scrubbing, cyclonic separation, product dewatering,fines thickener,fines dewatering, a process water storage tank, process water pond, slurry pond, 7