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Mr. Dick Wolfe, P.E., October 8, 2014 Page 3 Dust Control Water used by AFS for dust suppression on the Worthing site is taken from the exposed ground water in the Worthing Pit utilizing temporary pumping equipment. Dust suppression at the Worthing Pit is estimated to be approximately 1.0 acre -feet through May 2015 (see Table 2). Pumping from the Worthing Pit for the purpose of dust suppression will not occur beyond May of 2015. A well permit for the Worthing Pit (Permit No. 76903 -F) was obtained in December 2012 as part of the SWSP renewal process. The use of pumping equipment in the Worthing Pit was approved in a January 17, 2013 letter written by Mathew A. Sares pursuant to a request for variance submitted by AFS (Request No: 2013- 004A). Total Demand As shown in Table 2, the total estimated 2015 water demand at the Worthing Pit associated with evaporation and dust suppression is 1.64 acre -feet. B. DEPLETIONS Depletions at the site do not hit the river instantaneously and must therefore be lagged back to the river. AFS estimated the lagged depletions from the 2015 plan year as well as the post -plan year depletions associated with the 2014 Plan using the IDS Alluvial Water Accounting System (AWAS). The distance between the exposed water at the Worthing Pit and the South Platte River edge is 437 feet as measured from the centroid of the lake. AFS estimated the alluvial aquifer transmissivity to be 100,000 gpd/ft with a specific yield of 0.2. A summary of the AWAS input parameters used in the model are shown in Table 3. Lagged Depletions The AWAS analysis indicated that the Post -plan depletions associated with AFS's use during the 2014 Plan (i.e., 16.02 acre -feet) were 0.32 acre -feet occurring within the first three months of 2015. The estimated schedule of depletions resultant to the 2015 plan year water use of 1.64 acre -feet as well as the post -plan depletions from 2014 is summarized in the attached Table 4. There are no lagged depletions that last beyond the 2015 Plan Year. Total 2014 Plan Year Depletions Requiring Replacement The monthly replacements required by AFS in 2015 are summarized Table 5. The 2015 replacement requirements include post -plan depletions from 2014 (i.e., 0.32 acre -feet) and the depletions associated with 2015 water usage (i.e., 1.64 acre - feet). The delivery point for augmentation water is located approximately 12.0 miles upstream of the mining operation. Transit loss is estimated at 0.5 percent per mile, resulting in a 6.0 percent overall transit loss. AFS calculates a total 2015 plan year replacement requirement, including transit loss, of 2.07 acre -feet (see Table 5).