2012-03-30_HYDROLOGY - M1999050 - Laserfiche WebLink

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Mr. Jared Dains • Timnath- Connell SWSP March 30, 2012 Page 2 control. There are approximately 8 acres of exposed ground water at the site. 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 annual consumptive use from evaporation and operational uses at the site is 20.3 acre -feet. The lagged depletions from the Timnath - Connell Pit were estimated by the Applicant's consultant using the Alluvial Water Accounting System (AWAS) stream depletion model developed by the Integrated Decision Support Group with the following assumptions: • Distance from the gravel pit centroid to the river (X) = 2,500 ft • Alluvial aquifer width (W) = 5;300 ft • Specific yield (S) = • Transmissivity (T) = 50,000 (gpd /ft) The stream depletion model shows that the Timnath - Connell Pit's stream depletion will equal approximately 24.4 acre -feet during the approval period as shown in the attached Table 2. The Applicant has continuously dewatered the Timnath - Connell Pit since 1999. Water pumped for dewatering is discharged into the adjacent recharge pond. This diversion into the pond is not a part of the metered Box Elder Ditch Shares that are also discharged into the recharge pond. The dewatering depletions are lagged to the river using the same parameters as the other lagged depletions from the Timnath - Connell Pit as described above. The dewatering accretions are lagged to the river using the same parameters as the site depletions with the exception of using a distance from the centroid to the river (X) of 3,000 ft. This dewatering operation creates lagged accretions that mimic the lagged depletions. Thus at the cessation of dewatering the only depletion that would hit the river is that which is attributable to the first fill of the pit. The Applicant intends to line the pit when mining activity is complete thereby eliminating the depletion caused by the first fill. Should dewatering cease prior to the pit obtaining a liner approval from the Division Engineer, the Applicant must address the lagged depletions due to the "first fill." The SerFer Pit (DRMS M- 2008 -006, WDID 0303028, SWSP WDID 0302534) is also owned by Connell Resources, Inc. and relies on the Timnath - Connell SWSP to provide excess accretions to the SerFer SWSP. This must be accounted for in the Timnath - Connell SWSP by showing the accretion credits as a depletion against this plan. For this approval period, the total `depletion' to the Timnath - Connell Pit to be credited to the SerFer Pit is 6.93 acre -feet. Replacements The source of replacement water for this combined plan will be from 2.5 Box Elder Ditch shares (WDID No. 0300926). The shares will be diverted into a recharge pit (WDID 0302596) 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. 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.