2020-08-09_PERMIT FILE - M2020041

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Peak Ranch Resource August 5, 2020 3.0 FLOODPLAIN The 100-year floodplain is shown on Maps C-1, C-2 (A, B, &C), and Maps F-1 and F-2. There will be no mining within the FEMA designated 100-year flood plain at the Peak Ranch Resource site. 4.0 WETLANDS Monitoring the water levels in wells P-1 through P-6 and GW-2 and GW-5, all bored near the wetlands and shown on Map C-1,will allow Peak Materials to monitor and assess potential changes in groundwater elevations due to the Town of Breckenridge's planned maintenance of its on-site drainage system'. The source of water for the wetlands is originating from drainage water flowing onto the property from the highway culverts and spreading over the land due to the placement of compacted fill in the ditch by the prior owners. Groundwater levels, recorded in the wells in the vicinity of the wetland area, do not indicate that groundwater is a main source for the wetlands. Following maintenance activities by the Town of Breckenridge to their drainage easement, it is possible that the wetlands could lose their source of water and eventually dry-up. However,the wetlands will be protected from mining activity by a 25-foot buffer throughout the mine life and the wet mining process during Phase 2. 5.0 LOCATION ON MAP See Map C-1 for the location of all tributary water courses,wells, springs, stock water ponds, reservoirs, and ditches on the affected land and on adjacent lands where such structures may be affected by the proposed mining operations. Map C-1 also shows the location of groundwater monitoring wells and surface water sample points. 6.0 KNOWN AQUIFERS The only known aquifer in the area is the shallow alluvial aquifer of the Blue River. Depth to water table in the permit area varies depending on location and time of year but averages roughly 12 feet below ground surface. According to the U.S. Geological Survey's Ground Water Atlas of the United States,there are no other major aquifers or aquifer systems located beneath the area of the Peak Ranch Resource site2. 7.0 SURFACE WATER The Peak Ranch Resource site will interact with surface water in the area via runoff that enters the site. Runoff flow direction prior to mining is shown on Map C-1. Map C-2C shows the drainage direction during mining. Map F-1 shows the drainage direction once reclamation is complete. The priority for surface water protection at the Peak Ranch Resource is preventing the discharge of sediment, oil, and/or hydraulic fluids from the operational areas. Oil and hydraulic fluids are contained on the site using standard best management practices related to the storage and transfer of such fluids. These include the use of secondary containment around storage and transfer points, spill kits, and employee training on safe handling practices. Sediment is trapped onsite using controls and best management practices related to directing and controlling surface water runoff that enters disturbed areas. There will be no surface discharge from the mining area of the Peak Ranch Resource site. Stormwater that drains towards and through the site will not come in contact with disturbed areas and will continue to flow west to the Blue River, similar to the historic drainage condition. ' The Town of Breckenridge owns a drainage easement across the property for the purpose of ensuring that historically irrigated lands within the original Ranch property remain dry.The dry-up involves historic agricultural ditches that once served the property,commonly referred to as the"Hill Ranch Water." Dry-up is required by water court decrees that were entered in the Town's water right plan for augmentation and exchange(Case Nos.80CW444,81CW107,81CW487 and 81CW488(the"consolidated Cases")and Case No. 83CW51. 2 httos:Hpubs.usgs.goy/ha/ha730/ch c/ Gm 1.cwicki and Aswistm PHA' G-2