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

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Yrs. 1-10 Yrs. 11-35 Avg. Haul Length (miles) 1.6 2.0 Max. Haul Length (miles) 2.0 2.5 Est. Round Trips/day 349 349 As part of the truck hauling operations, numerous temporary haul roads will be built between the active pit and the facility.These temporary haul roads will allow trucks to transport raw plant feed to the processing plant. Haul roads will be graded and watered to suppress dust. Other temporary haul roads may be needed to allow access to the reclamation areas for deposition of backfill materials to be used in the regrading and reclamation of previous mining operations.These temporary haul roads will be reclaimed as part of the final reclamation process throughout the site. 6.4.4(c)Water Diversions& Impoundments-A temporary sediment basin and associated diversions will be built during the construction phase to collect runoff from storm events that occur during the construction of the site facilities.Water will infiltrate and evaporate or be pumped out and discharged to the nearby undisturbed buffer areas around the edge of the processing facility.This temporary sediment basin may be converted into a permanent non-discharging stormwater retention pond that will gather stormwater runoff water received at the facility, if required.A typical cross section of a sediment basin is provided in Figure D1. See Figure D3,Site Plan,for a general location of the temporary sediment basin. Berms will be constructed around the fueling station,above ground fuel storage tank secondary containment, and ready line (truck staging area)to direct runoff away from the area.Any stormwater runoff that falls directly in the fueling station and ready line area will be directed to a small settling pond that will allow the water to be inspected for potential hydrocarbons and treated and then discharged to nearby undisturbed buffer areas.All water temporarily captured by this small settling pond will be released back into the system within 72 hours. Figure D2 shows a typical cross section of the settling ponds. Please see Figure D3, Site Plan,for a general location of the settling pond at the fueling station. Dewatering of the pits is not expected to be needed as mining will occur only above the water table. Berms at the top of the active mining areas will be used to direct stormwater runoff away from the active pit.Small settling ponds will be used to temporarily hold any stormwater runoff that gathers in the pit area.Stormwater will be removed through small pit sumps using a pump system that will be designed for the site.Settling ponds will be placed near the active mining operations as necessary throughout the life of the mine and will be reclaimed as part of the ongoing reclamation process as they are no longer needed.These settling ponds will be located far enough from the pit to ensure pit stability. Water pumped from the pits will be inspected for potential hydrocarbons and, if necessary,treated, and then water will be allowed to infiltrate or will be discharged to nearby undisturbed buffer areas. See Exhibit C6.1 and C6.2, Mining Plan Map,for a few conceptual locations of the settling ponds as mining operations progress. Figure D2 shows a typical cross section of the settling ponds. Table D2 shows the estimated size and volume of the proposed temporary sediment basin and settling ponds. Pond size has been calculated using the rational method and the 100-yr, 1-hr storm and 10-yr, 1-hr storm numbers provided by NOAA's Precipitation Frequency Data Server, as required by Weld County regulations for drainage and grading calculations for non-urbanized areas.Three conceptual settling ponds were sized and calculations have been provided for mining operation years 1-11.The pond sizes are based on the maximum number of acres that would be disturbed at any one time and does not take into account concurrent reclamation.Actual settling pond size may vary and will be based on on-site needs for ongoing operations. All ponds have been designed with side slopes of 3:1 (H:V). 3