7.3. SR 01-21-2014 - Laserfiche WebLink

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Active mining and asphalt plant operation has occurred on this Site for many years. Berms have been constructed along US Highway 169 and a portion of 221st Ave. The berms are vegetated and landscaped and provide screening. Site terrain is irregular with little topsoil or overburden. Elevations range from 960 to 1070 feet above mean sea level (msl) with typical slopes ranging from 20-30% and mining faces of approximately 1.5:1 (H:V). Mining is proposed to occur to elevations ranging from 946-961 feet above msl.The expansion parcel is an extension to the south of the existing permitted mining area and includes a residential structure and outbuildings. The expansion parcel also contains some wooded areas as well as brush and grassland. The southwestern portion of the northern parcel also contains woods and open space. Sheet C1, Existing Conditions, illustrates the current topography of the Site. Based on information contained on the National Wetland Inventory (NWI) Map,there is one wetland located on the Site in the very southwestern corner of the northern parcel. The wetland basin is predominantly off-site but a portion extends about 70 feet into the Tiller property. The portion of the wetland that is located on the Site is located within the 200-foot setback area and the trail system right-of-way. A 140-foot buffer is maintained between the wetland and the excavation limits. Vegetation will remain and no land disturbing activities will occur within the buffer area. The wetland is not proposed to be impacted by the mining operations.Tibbits Brook, Rice Lake and a large wetland complex lie northwest of the Site on the west side of the abandoned railroad track. Figure 3,NWI Excerpt, illustrates the location of nearby wetlands. The Site lies immediately south of the existing Elk River Landfill. Other surrounding land uses are primarily agricultural or mineral extraction. Figure 4, U.S.G.S. Quad Map Excerpt, illustrates the Site setting. c. Estimate of Quantity of Material to be Mined: An estimated 10 million cy of marketable material remains on the Site. d. Depth of Water Table: The depth of the water table was identified during the EIS process. The water table ranges from about 957 feet above mean sea level (msl) in the northern portion of the Site to about 945 feet above msl in the southeast corner of the Site. A groundwater divide, running approximately northeast-southwest runs through the Site. Mining under this permit will occur to the elevation of the water table and then backfill to the reclamation grades. e. Average thickness of overburden The average thickness of overburden is estimated to range between 0 and 5 feet. The overburden is a sandy loam. f. Detailed map of haul routes to Elk River City Limits: Page 14