2012-02-16_REVISION - M2002020 (9)

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Water Information The 25 Avenue Site and proposed amendment area are located in Section 36, Township 6 North, Range 66 West of the 6` Principal Meridian, Weld County, Colorado. However, prior to this application approval, the entire 25` Avenue Site and proposed amendment area are planned to be annexed into the City of Greeley. The proposed amendment area includes 197.51 acres. Including the 87.05 acres in the existing 25 Avenue Site, the total proposed permit area is 284.56 acres. The Cache la Poudre River bisects the northern portion of the proposed amended area from west to east. Other water resources near the site include City of Greeley stormwater drainage ditch located adjacent to the west permit boundary and discharging into the Poudre River at the northwest corner of the site. The Greeley No. 3 Canal is approximately 2,800 feet south of the proposed permit boundary (see Exhibit C -4, Water Resource Map). As delineated on Map Numbers FM0802660609C and FM0802660628C (National Flood Insurance Program, September 28, 1982), a large portion of the 25 Avenue Site and proposed amendment area lies within the Cache la Poudre River 100 -year floodplain (see Exhibit C -4, Water Resource Map). All work performed in the floodplain will conform to the City of Greeley Flood Fringe Development Regulations. Introduction Potential Mining Impacts EXHIBIT G The proposed amendment area includes four groundwater ponds with a combined surface area of approximately 75 acres. The pond cavities were excavated in the Cache la Poudre alluvium during previous mining activities. During mining, alluvial groundwater was pumped from the pits to facilitate sand and gravel excavation and processing. Following the completion of mining and removal of the dewatering pumps, alluvial groundwater filled the pits to create the existing ponds. The ponds currently impact the Cache la Poudre River in the form of depletions due to evaporation. The new mining operation will impact groundwater systems hydraulically connected to the Cache la Poudre River by extracting sand and gravel deposits from the alluvial aquifer. These impacts will be covered under a Substitute Water Supply Plan (SWSP) for the replacement of stream depletions obtained from the Colorado State Engineer's Office (SEO). Additionally, a well permit (Permit No. 59809 -F) for exposed groundwater has already been obtained from the SEO. The new mining operation will impact groundwater systems hydraulically connected to the Cache la Poudre River by extracting sand and gravel deposits from the alluvial aquifer. These impacts will be covered under an SWSP obtained from the SEO. This unconfined alluvial aquifer rests atop bedrock formations of the Laramie Formation, Fox Hills Formation, and Pierre Shale. Water below the property within this portion of the Laramie -Fox Hills is non - tributary. Reclamation activities will not produce additional significant long -term affects to the alluvial Greeley 25` Avenue Site DRMS 112 Permit Amendment Application Page 18