2010-02-22_HYDROLOGY - M1977522 - Laserfiche WebLink

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Mr. Jared Dains, E.I. February 19, 2010 Page 2 January 1, 1981. Accordingly, the evaporative depletions for the Feit Pit were calculated based on an exposed surface area of 34.1 acres exposed after December 31, 1980. The estimate of evaporative losses under this plan was also reduced during the ice covered period. You have assumed the ice covered period to occur during the months of December and January based on the average temperatures of 29.4°F for December, 28.6.0°F for January. Temperature data were obtained from the Greeley UNC weather station (053553) for the time period of 1967 through 2005. The ice covered periods may be used to reduce the amount of evaporative losses that need to be replaced; however, for the purpose of this SWSP, the Applicant shall replace the net evaporation depletions from the exposed ground water surface area that may occur during the assumed ice covered period (December and January) for any time that the pits are not completely covered by ice. Computation of1he net evaporation during any time that the pits are not completely covered by ice shall be determined as the pro-rata amount of the monthly gross evaporation rate distribution amount identified in the State Engineer's General Guidelines for Substitute Supply Plans for Sand and Gravel Pits, subtracting the pro-rata amount of the effective precipitation for that period. The attached Tablet identifies the estimated monthly depletions from evaporation. According to your letter, Star Ready Mix does not anticipate any mining will occur at the site during WY 2010; however, water is anticipated to be used for concrete production, dust control, and for drinking and sanitary purposes. The monthly breakdown of the annual depletions total 94.08 acre-feet of evaporative loss, 0.8 acre-feet of water used and consumed for dust control, 3.1 acre-feet of water used in concrete production, and 0.11 acre-feet of water used for drinking and sanitary purposes. The water used for drinking and sanitary purposes is to be withdrawn from well permit no. 57724-F. No phreatophyte credit has been applied to this plan. 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 steam 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 plan were estimated to be 98.06 acre-feet as shown on the attached Table 3. Replacements The sources of replacement water to be used for this plan 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 2009 through March 2010, a lease of 16.12 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