2023-07-19_REVISION - M2021052 (7)

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Rifle Gravel Pit#i July 2023 Table 3. Water Use Demands for Active Mining Gross Water Evaporation Amount of Water Lost Used for -Exposed Domestic/ Total Operational Aggregate With Mined Du Water Commercial Water Use Dust Production' Aggregate Control' Surface Indoor Uses Area: 12.56 acres Volume Avg Rate Month tons AF AF AF AF AF m Jan 0 0.00 0.00 0.00 0.00 0.00 0.00 Feb 0 0.00 0.00 1.65 0.00 1.65 13.33 Mar 0 0.00 0.00 2.59 0.00 2.59 18.91 Apr 13,125 0.39 2.30 4.24 0.00 6.93 52.27 May 13,125 0.39 2.38 5.65 0.00 8.41 61.39 Jun 13,125 0.39 2.30 6.83 0.00 9.52 71.81 Jul 13,125 0.39 2.38 7.07 0.00 9.83 71.75 Aug 13,125 0.39 2.38 6.36 0.00 9.12 66.57 Sep 13,125 0.39 2.30 4.71 0.00 7.40 55.82 Oct 13,125 0.39 2.38 3.30 0.00 6.06 44.24 Nov 13,125 0.39 2.30 1.88 0.00 4.57 34.47 Dec 0 0.00 0.00 0.00 0.00 0.00 0.00 Total 105,000 3.09 18.72 44.28 0.00 66.08 Notes: 1) Projected mining provided by Scott. Total aggregate extraction is expected to be 420,000 tons over 4 years. Mining will operate 8 months of the year(Apr-Nov). [420,000 tons]/[4 years]/[8 months]=13,125 tons/month. 2) Column (1)x[4% by weight(lb water per lb aggregate)]x[2,000 lb/ton]/[62.4 lb water/cubic foot]/ [43,560 cu. ft. /AF] 3) [25,000 gal/day] x[total#of days/month]/[325,851 gal/AF]. Dust Control demand provided by Scott at 25,000 gallons per day. 4) Based on SEO Gravel Pit guidelines (4/1/2011)for elevations below 6,500 feet,45 inches (annual evaporation from NOAA Technical Report NWS 33, Map 3), and assumption of zero evaporation during December and January when gravel pit is iced over. Mean monthly temperature was 31.99 deg F in February.As this is close to 32 deg F, evaporation for this month was considered to provide a conservative estimate considering the impacts of climate change. 5) No planned domestic or commercial water use sourced from Rifle Pit property. 6) Equals sum of individually-calculated components 53