2009-12-16_HYDROLOGY - M1999050 - Laserfiche WebLink

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Ms. Sira W. Sartori Page 2 Stute Pit -M81 -007 and Timnath - Connell Pit -M99 -050 December 15, 2009 Depletions This plan wilt: account for the delayed evaporative depletions from the previously exposed ground water surface area at the Stute Pit. The lagged depletions from the Stute Pit were estimated by the Applicant's consultant using the Glover method, with an estimated distance from the site to the no flow aquifer boundary (which is perpendicular to the point of impact) of 5,000 feet, an estimated distance from the pit to the Cache la Poudre River of 3,300 feet, an aquifer transmissivity of 50,000 gpd /ft, and a specific yield of 0.2. The lagged stream depletions are estimated to total 0.4 acre -feet during the term of this approval. The Timnath - Connell Pit will continue to be mined with an estimated 200,000 tons of aggregate to be mined during the term of this approval, resulting in 5.9 acre -feet of water lost in the mined product, and 0.8 acre -feet of water to be used for dust control. Gross evaporation at the Timnath - Connell Pit is estimated to be approximately 39 inches /year and with an annual effective precipitation amount of 0.8 feet (9.6 inches), net annual evaporation is estimated to be approximately 2.4 acre -feet per acre (29 inches). For the 8.0 acres of ground water exposed at this site, annual net evaporation is estimated to be 19.5 acre -feet. The total consumptive use from evaporation and operational uses at the site is 26.2 acre -feet. The lagged depletions from the Timnath - Connell Pit were estimated by the Applicant's consultant using the Glover method, with an estimated distance from the centroid of the pit to the no flow aquifer boundary (which is perpendicular to the point of impact) of 8,500 feet, an estimated distance from the centroid to the Cache la Poudre River of 2,500 feet, an aquifer transmissivity of 50,000 gpd /ft, and a.specific yield of 0.2. Total lagged depletions at the Timnath - Connell Pit are 29.9 acre -feet for WY 2010. The total lagged stream depletions for this plan are 30.3 acre -feet, as shown in the attached Table 2. Replacements The source of replacement water for this combined plan will be from 2.0 Box Elder Ditch shares (WDID No. 0300926). The shares will be diverted into a recharge pit located on the Timnath- Connell site. The recharge pit was constructed in an area of the mining site that was previously excavated for sand and gravel mining. The evaporation losses listed in Table 2 for the Timnath- Connell Pit include the evaporation losses from the recharge pond. In 2010, 2.0 shares will be diverted into the recharge pond to provide replacement water for this combined plan. Connell Resources, Inc. owns 4.0 shares in the Box Elder Ditch that were historically used to irrigate the property known as the John Weitzel Farm, which is the site of the Timnath Connell Pit. Connell Resources also owns 0.5 shares of the 3.5 shares Box Elder Ditch shares that were historically used to irrigate the property known as the Robert Weitzel Farm, which is now divided into two mining sites ( Stute Pit and Weitzel Pit). The 0.5 shares used on the Robert Weitzel property is not to be used for this plan. The historical consumptive use of the 4.0 Box Elder Ditch shares used on the John Weitzel property is estimated to be 170.72 acre -feet and the return flow obligations for these 4.0 shares for October through April is 89.52 acre -feet. This quantification is based on the average headgate diversions for the Box Elder Ditch for the years 1950 to 2004 assuming 10% ditch loss and 55% field efficiency.