2011-11-16_HYDROLOGY - M1977522 - Laserfiche WebLink

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Mr. Jared Dains, E.I. Page 3 November 16, 2011 According to your letter, Star Ready Mix anticipates 60,000 tons of material will be mined below the groundwater table during WY 2012, resulting in 1.77 acre -feet of water lost in mined product. The applicant calculated the water lost due to the intermittent fill of the pit to be 13.66 acre -feet, and expects 0.8 acre -feet of water to be used for dust control. The total operations water loss for WY 2012 is 16.23 acre -feet The estimated monthly depletions due to operational losses are shown on the attached Table 2. As in the in previous SWSP, it was determined that the average down - gradient extent of the exposed groundwater is approximately 250 feet from the Cache La Poudre River. Therefore, a stream depletion model was used to determine the timing of lagged depletions to the Cache La Poudre River. The following parameters were used in the stream depletion model: transmissivity (T) = 120,000 gallons per day per foot, specific yield (SY) = 0.2 (which is typical for an alluvial aquifer), the distance of the exposed ground water to the river = 250 feet, and the location of the parallel impermeable boundary was estimated to be 4,300 feet from the stream. Based on the above factors, the lagged stream depletions for the term of this SWSP were estimated to be 109.80 acre -feet as shown on the attached Table 3. According to the Applicant, the distance from the surface of the exposed ground water area to the Cache La Poudre River was measured based on the average down - gradient extent of the exposed ground water surface. For purposes of this SWSP, the method used to measure the distance to estimate the lagged depletions will be accepted, however any future SWSP must measure the distance from the exposed ground water surface area to the Cache La Poudre River based on the centroid of the exposed ground water surface. Replacements The sources of replacement water to be used for this SWSP are 1) fully consumable replacement water leased from the Platte River Power Authority, and 2) augmentation water leased from the Graham Drainage Ditch Company. During the period of November 2011 through March 2012, a lease of 16.9 acre -feet of fully consumable water provided by the Platte River Power Authority ("PRPA") will be used to make replacements during the non - irrigation season. PRPA has an "Agreement for the Reuse of Water for Energy Generation ", dated August 10, 1978, with the City of Fort Collins ( "Fort Collins ") and Water Supply and Storage Company( "WSSC ") that provides PRPA with the right to receive reusable water delivered by Fort Collins. PRPA, Fort Collins, and WSSC also obtained approval of a plan for augmentation including reuse of water in Division 1 Water Court Case no. W- 9332 -78. In case no. W- 9332 -78, the Court found that 4,200 acre -feet, or more per year, will be available from Fort Collins to the PRPA to be used primarily for cooling purposes in connection with its Rawhide Energy Facility. Pursuant to the decree in case no. W- 9332 -78, if PRPA does not require the water for its own purposes, PRPA, Fort Collins, or other water users may utilize the water for any other beneficial purpose including augmentation. In addition, PRPA has entered into an Agreement with the North Poudre Irrigation Company ( "North Poudre ") dated November 15, 1979 which grants PRPA the right to store surplus water (which is surplus water beyond the needs of the Rawhide Energy Facility) in Fossil Creek Reservoir and lease such water to others who can use such water from Fossil Creek Reservoir through direct delivery. As required by the Agreement, North Poudre and the water commissioner were informed by the