5.2 PCSR 01-24-2017 - Laserfiche WebLink

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Active mining will begin by stripping topsoil and overburden from a portion of the Site. Overburden and topsoil will be shaped into perimeter berms. To reduce exposed soils and the potential, dust, sedimentation and erosion, stripping and construction of berms will occur in phases as mining progresses through the Site. Berms will be constructed to maintain existing drainage patterns. Extraction of the aggregate deposit will be accomplished with loaders and excavators. Mining will extend into the water table. Sand and gravel will be mined below the water table using wet mining methods; a backhoe, drag line or dredge. The depth of excavation below the water table will be an average of 25 feet but may extend to 50 feet or more depending upon the quality of aggregates encountered and equipment utilized. Mining below the water table may occur over any portion of the floor of the mine. Portions of the excavation below the water table will be backfilled after mining as part of Site reclamation activities. Processing equipment; crushing, screening and wash plants, will be located in recessed areas of the Site to provide screening and reduce dust and sound emissions from the Site. The primary crusher will typically be located adjacent to the active face where materials will be crushed and then conveyed or hauled to the main processing area for additional crushing, screening and or washing. Material stockpiles will be established around the processing plants. The washplant will operate seasonally during nonfreezing weather conditions (generally April — November). The washplant will discharge process water into a series of on -site ponds that will be established on the floor of the mine. These ponds will allow fine sediments that are in the washwater discharge to settle. Clarified washwater will be returned to the washplant for reuse. Washwater will not be discharged from the Site. Portable toilets will be used at the Site to serve employees. Mining and processing will be subject to setbacks established by the City of Elk River Mining Ordinance. Proposed setbacks include a 30 -foot setback from all road right -of -ways and parcels not permitted for mining operations. The northern border and a majority of the southern border are adjacent to permitted or future mining operations and therefore do not require a setback. No explosives will be used at the Site. 4.6 Drainage, Erosion Control, Sedimentation, Dust, Access Control and Security: The majority of the Site drains internally. Sheet C -1: Existing Conditions, illustrates the current topography and drainage patterns of the Site. Disturbed areas of the Site will be graded to drain internally. The Site will operate under the General Minnesota National Pollutant Discharge Elimination System Permit ( NPDES) permit for non - metallic mining mineral mining and associated activities. Prior to commencing operations, a site specific Stormwater Pollution Prevention Plan (SWPPP) will be prepared for the Site as required by the NPDES permit. Best management practices, such use of silt fence, drainage swales and diversions and progressive reclamation will be implemented at the Site to control erosion and off -site sedimentation. Perimeter berms may be constructed within setback areas, shaped, and stabilized with vegetation. Based on information from the National Wetland Inventory Maps, there are no wetlands located on the Site. Information from the NSC soil survey indicates that there are no hydric soils on the Site. According to the Natural Resources Conservation Service Soil Survey, Site soils consist of the Max Steininger, Inc.: Elk River Sand and Gravel Mine 5 1 P a g e Zone Change & Conditional Use Permit Application December 2016