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Rifle Gravel Pit#1 July 2023 <br /> water. As sewer services are unavailable from City of Rifle or Town of Silt, Scott will provide <br /> portable toilets for wastewater needs. <br /> 8.7.6 Water Requirements During Reclamation Phase (Post Mining) <br /> After mining is completed, water depletions from the site will be solely from evaporation of <br /> the exposed groundwater in the finished gravel pit pond. Annual gross evaporation for the <br /> Rifle area is estimated at 45 inches based on the contours from National Oceanic and <br /> Atmospheric Administration Technical Report NWS 33 dated June 1982, Map No. 3. Annual <br /> evaporation was distributed annually using the DWR General Guidelines for Substitute <br /> Water Supply Plans for Sand and Gravel Pits (DWR Gravel Pit Guidelines) annual <br /> distribution for elevations below 6,500 feet. The evaporation was then reduced to account <br /> for periods when the pit is expected to be frozen over when the average temperature is <br /> below freezing, typically December through February for Rifle. <br /> The final surface area of the pond was originally estimated to be 12.56 acres and is <br /> estimated to have 44.28 AF of depletions annually. Table 4 presents the post-mining phase <br /> water use demand based on this estimate, although subsequent design changes have <br /> reduced the surface area of the pond to 9.70 acres. <br /> 52 <br />