2010-04-20_HYDROLOGY - M2001017 - Laserfiche WebLink

Home Browse Search

Mr. Rick Parsons, P.E. L.G. Everist Combined Replacement Plan April 19, 2010 Page 4 of 9 of evaporation under this plan was reduced during the ice covered periods. You have assumed the ice covered period to occur during the months of December, January and February, based on average monthly temperatures less than 32°F taken from the Longmont 2ESE weather station for the Saint Vrain Creek Pits and Fort Lupton 2SE station for the South Platte Pits. 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, February and December) for any time that the pit is not completely covered by ice. Computation of the net evaporation during any time that the pit is 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 material excavated from the gravel pits is estimated to be approximately 72 percent below the water table and approximately 28 percent above the water table. According to the new "General Guidelines for Substitute water Supply Plans for Sand and Gravel Pits" the product moisture loss is calculated as four percent by weight of mine material excavated below the ground water table and two percent by weight for the mined material excavated above water table. Water used for dust control at Lohmann Pit and Rinn Valley Pit will come from water originally pumped from the pits for dewatering. Water used for dust control at the Fort Lupton Pit and the Lupton Meadows Pit will come from an existing alluvial well, permit no. 57957-F (WDID 0205018 DI TIRRO WELL 2), located outside of the approved slurry wall on the Fort Lupton Pit site. Well permit no. 57957-F is permitted to provide water for concrete batching and dust suppression. The depletions resulting from pumping the well, for those uses, will be replaced under this plan. Depletions from each site were lagged to the stream system using the Glover method. The aquifer parameters associated with each pit are summarized in the attached Table 4.1. Replacements Saint Vrain Creek L. G. Everist owns 7.4 shares of the Rural Ditch Company. Of the 7.4 shares of the Rural Ditch water, 2 shares will be dedicated to this plan in 2010 and 1 shares will be dedicate for this plan for 2011. The 7.4 shares of the Rural Ditch were historically used to irrigate 215 acres of pasture grass, corn and alfalfa. The land historically irrigated by the 7.4 shares is the same land that is currently being mined at the Rinn Valley Pit. Assuming a 10% ditch loss and a 55% irrigation efficiency, the dry-year consumptive use of the 7.4 shares was determined to be 337 acre-feet. The prorated consumptive use for the 2 shares is 91.0 acre-feet and for the one share is 45.5 acre-feet. The historical return flow obligation of the two and one Rural Ditch shares will be maintained by the plan. The Rural Ditch shares are delivered to Saint Vrain Creek through an augmentation station near the end of the ditch. The delivery location is below the Last Chance Ditch headgate and above downstream calling water rights located on the South Platte River. L.G. Everist has entered into a lease agreement with Varra Companies, Inc ("VCI") for releases of stored water in the VCI 112 Pit Reservoir, located in the.NW1/4 of the SE1/4 of Section 2, Township 2 North, Range 65 West of the 6`h P.M. Consumptive use credits of VCI Rural Ditch shares that are not used to replace depletions during the irrigation season for other gravel pit SWSPs will be stored in the 112 Reservoir and subsequently released to replace non-irrigation season depletions. A decree for a