2014-04-22_HYDROLOGY - M2008006 - Laserfiche WebLink

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Mr. Todd Williams, P.E. Page 2 of 6 April 21, 2014 therefore the water retained in the mined product is considered to be 2.0% of the mined material by weight. This results in 3.53 acre -feet of ground water lost with the mined material. In the past, the Applicant has either trucked water from the Timnath- Connell Pit or used potable water supplies from fire hydrants in the vicinity of the SerFer Pit for dust control purposes at the site. However, the Applicant may install a truck loading station to allow the use of water from the SerFer Pit for dust control purposes. If this occurs, you have estimated that 4.00 acre -feet of water will be used at the site for dust control during this plan period. Water used for dust control purposes is assumed to be 100% consumed. Total operation consumptive use at the site is 7.53 acre - feet for this plan period (see attached Table 2). The total evaporative and operational consumptive use of ground water during the plan approval period is 9.03 acre -feet. The Alluvial Water Accounting System (AWAS) stream depletion model developed by the Integrated Decision Support Group was used to determine the lagged depletions from the SerFer Pit to the Cache La Poudre River from past and projected evaporation and operational losses at the site. The following parameters were used in the model: • Distance from the gravel pit centroid to the river (X) = 600 ft • Alluvial aquifer width (W) = 4,300 ft • Specific yield (S) = 0.2 • Transmissivity (T) = 45,000 (gpd /ft) Lagged stream depletions are estimated to total 8.44 acre -feet during this plan period, as shown on the attached Table 3. It is the understanding of this office that this site is continuously dewatered. As long as meter readings are submitted to this office demonstrating a continuously dewatered condition, the operator may continue to assume that the water returned to the stream system is adequately offset by the depletions attributable to the dewatering operation. Replacements The primary source of replacement water for this plan is excess recharge credit from the Applicant's Timnath- Connell Pit SWSP (WDID 0302526). As more completely described in the Timnath- Connell SWSP, 2.5 shares of the Box Elder Ditch Company, owned by Connell Resources, will be diverted into a recharge site (WDID 0302059) at the Timnath- Connell Pit. The evaporation losses and operation of the recharge site are covered by the Timnath- Connell Pit SWSP. This recharge site is located approximately 4 miles upstream of the SerFer Pit location. Both the recharge site and the SerFer Pit impact the Cache La Poudre River at or about the east quarter corner of Section 3, T6N, R68W, 6th P.M., approximately 1.5 miles upstream of the New Cache la Poudre Irrigating Company (aka Greeley No. 2 Ditch) headgate (WDID 0300929). As such, a transit loss of 1.0% (0.25% per mile) is assessed to the recharge credits to be used for replacement purposes at the SerFer Pit site. During the months of May, June, and July, excess recharge credits alone will be insufficient to replace depletions from the SerFer Pit. The Applicant has obtained a lease of a total of 4.3 acre -feet of reusable water from the City of Fort Collins in order to make replacements for the Timnath- Connell Pit and the SerFer Pit during these months. The leased water will first be used to replace any depletions unable to be met by recharge at the Timnath- Connell Pit, with any excess water available for use for replacement purposes at the SerFer Pit. The Applicant must notify the water commissioner prior to the release of the City of Fort Collins reusable water from Fossil Creek to ensure the water is properly accounted for in the Fossil Creek reservoir accounting. A transit loss will be assessed for the distance from the outlet of Fossil Creek Reservoir (WDID 0303774) to the Poudre River to the SerFer Pit.