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Mr. Scott Pelino <br /> November 27, 2018 <br /> Page 2 of 5 <br /> credit has been applied to this plan. The replacement water for this pit will be provided by a <br /> lease with Upper Arkansas Water Conservancy District. <br /> In accordance with the letter dated April 30, 2010 from the Colorado Division of <br /> Reclamation, Mining, and Safety("DRMS"), all sand and gravel mining operators must <br /> comply with the requirements of the Colorado Reclamation Act and the Mineral Rules and <br /> Regulations for the protection of water resources. The April 30, 2010 letter from DRMS <br /> requires that you provide information to DRMS to demonstrate you can replace long term <br /> Injurious stream depletions that result from mining related exposure of groundwater. <br /> In accordance with approach nos. 1 and 3,you have indicated that a bond has been <br /> obtained for$54,000 through the Division of Reclamation, Mining, and Safety("DRMS")to <br /> assure that depletions from groundwater evaporation do not occur in the unforeseen <br /> event, or events, that would lead to the abandonment of the Pit. <br /> Depletions <br /> The anticipated net depletions for this SWSP are 2.32 acre-feet per year. The currently <br /> exposed groundwater at the site totals 0.40 acre, within the existing ponds (0.38 acre)and a <br /> drainage ditch (0.02 acre). The drainage ditch is approximately 350 feet tong and <br /> approximately two feet wide and drains water to the existing ponds by gravity. Gross annual <br /> evaporation at the gravel pit location is estimated to be 39.0 inches per year. Using the <br /> climate data from the Buena Vista weather station the net evaporation for the 0.40 acre <br /> exposed at the site is estimated to be 1.06 acre-feet. <br /> You have provided a monthly breakdown of the annual depletions made up of 1.06 <br /> acre-feet of net evaporative loss, 0.26 acre-foot of water lost with the mined product (which <br /> represents 9,000 tons of mined product), and 1.00 acre-foot of water used for dust control. <br /> The total annual depletion is 2.32 acre-feet. <br /> These depletions have been lagged to the Arkansas River. The aquifer parameters used <br /> In the stream depletion model are as follows: 1)X=250 feet(distance from the centroid of the <br /> exposed surface area to the river), 2)W=2,300 feet (distance from the aquifer impermeable <br /> boundary to the river channel), 3)T=50,000 gal/day/foot (transmissivity of the alluvial <br /> aquifer), and 4) S-0.2 (specific yield). The total annual for the lagged depletions is 2.26 <br /> acre-feet. <br /> Replacement <br /> The proposed source of replacement water for this pit is a lease for 2.32 acre-feet of <br /> fully consumable water from the Upper Arkansas Water Conservancy District. The leases are <br /> attached to this letter. Transit losses will be assessed by the Water Commissioner and Division <br /> Engineer. <br /> The monthly depletions and replacement requirements are found on the attached <br /> Table 3. The previous SWSP indicated a need for a depletion volume for a "first fill"which <br /> would be necessary if the site was being dewatered. Since this is not the case, the first fill <br />