2023-07-19_REVISION - M2021052 (7)

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Rjfle Gravel Pit#1 July 2023 Table 4. Water Use Demands for Post Mining Gross Gross Pond Pond Unit Gross Evaporation -Exposed Unit Evap Feb- Water Surface Area: 12.56 Evaporation' Nov2 acres Month AF/acre AF/acre Volume AF Avg Rate m Jan 0.11 0.00 0.00 0.00 Feb 0.13 0.13 1.65 13.33 Mar 0.21 0.21 2.59 18.91 Apr 0.34 0.34 4.24 31.98 May 0.45 0.45 5.65 41.24 Jun 0.54 0.54 6.83 51.52 Jul 0.56 0.56 7.07 51.61 Aug 0.51 0.51 6.36 46.43 Sep 0.38 0.38 4.71 35.53 Oct 0.26 0.26 3.30 24.09 Nov 0.15 0.15 1.88 14.18 Dec 0.11 0.00 0.00 0.00 Total 3.75 3.53 44.28 Notes: 1) 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), 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] 2) Based on 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. 3) Equals Active Surface Area times gross evaporation. 8.8 Colorado Discharge Permitting System (CDPS) Permit and U.S. Army Corps of Engineers (USACE) Permitting Scott has an approved CDPS Construction Stormwater Permit(Attachment G). Scott has secured a Boundary Confirmation letter from the USACE, confirming the accuracy of the wetland boundaries shown in this application, and affirming that no impact to wetlands that are jurisdictional under Section 404 of the Clean Water Act would occur. Should a permit become necessary later(due to a temporary discharge need or similar), Scott will secure the necessary permit from the USACE. 54