2011-09-14_HYDROLOGY - M2010049 - Laserfiche WebLink

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Cheryl Signs, P.E. Western Sugar Pit In accordance with approach no. 4, you have provided an affidavit dated November 1, 2010 that dedicates five of the Applicant's shares of GIC water and 4 shares of the Rural Ditch water and portions of the water rights decreed in case no. 2001CW274 as replacement water solely for this SWSP, Durham Pit SWSP (M78 -056), Kurtz Pit SWSP (M99 -006), and Heintzelman Pit No. 116 SWSP (M09 -018) for as long as there are depletions at these gravel pit sites or until such time as another replacement source is obtained. A copy of the affidavit is attached to this letter. For the purposes of this SWSP, this affidavit will be accepted for the dedication of the shares; however, if the State Engineer determines that a different affidavit or dedication process is necessary to assure proper dedication of the shares, additional information may be required prior to future SWSP approvals. Depletions The anticipated net depletions for this SWSP are 184.80 acre -feet per year. This SWSP anticipates that a total of 62.81 acres of water surface will'be exposed at the site if dewatering ceases. The evaporation calculations were based on the entire exposed surface area in the event that the dewatering ceased and this SWSP will cover replacements for depletions associated with the 62.81 acres. However for purposes of accounting, depletions will be based on the ground water surface area actually exposed at the site. Replacements Page 2 You have provided a monthly breakdown of the annual depletions made up of 158.44 acre - feet of net evaporative Toss, 23.55 acre -feet of water lost with the mined product (which represents 800,000 tons of mined product), and 2.80 acre -feet of water used for dust control. Computation of evaporation under this SWSP was also reduced during the ice covered period. You have assumed the ice covered period to occur during the months of January and December, based on the average temperatures of 26.0 °F for January and 27.4 °F for December; taken from the Greeley weather station (053533). 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 (the months of January and December) for any time that the pit is not completely covered by ice. Computation of the net evaporation during any time that the pond is not completely covered by ice shall be determined as the pro -rata amount of themonthlygross 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 IDS AWAS stream depletion model was used to determine the lagged depletions from dewatering, evaporation and operational losses to the Cache La Poudre River. The aquifer characteristics used in the model are: transmissivity (T) = 100,000 gallons per day per foot, specific yield (SY) = 0.28 (based on the USGS Water Supply Paper 1662D), the distance from the stream to the centroid of the pit = 1,350 feet, and the location of the parallel impermeable boundary was estimated to be 2,600 feet from the stream. VCI proposes to provide replacement for this pit using water rights owned in the Last Chance Ditch, Godding Ditch, Rural Ditch, Hayseed Ditch, lined gravel pits (112 Reservoir, Dakolios Reservoirs and Von Ohlen Reservoir) and /or junior water decreed in case no. 2001 CW274. 7