2009-11-03_HYDROLOGY - M1978052 - Laserfiche WebLink

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Sira W. Sartori Page 3 October 27, 2009 replaced in time, place and amount. The Applicant is hereby notified that if dewatering at this site occurs only during the summer months and the pond is allowed to fill during the winter months the depletions that will have an effect on the stream as a result of refilling the pit, must be addressed in any subsequent SWSP renewal for this pit. The mining sites are set back from the river, therefore, the depletions from the operations were not assumed to be instantaneous. Operational and evaporative depletions at the site were lagged to the stream system using a Glover analysis and the aquifer parameters shown below: Site Name X ft W ft T( d/ft Specific Yield Howe Pit 350 12,000 45,000 0.2 Mann Lakes 400 4,450 45,000 0.2 Ft. Lupton Pit Stream De letion Factor of 300 days was used Lupton Lakes X 3,100 7,000 150,000 0.2 di - stance from well to river W-distance from the aquifer boundary through the well to the river channel T-transmissivity of the alluvial aquifer (in gallons per foot/day) between the well and the river The lagged mining depletions are shown in the attached Table 1. Replacements The proposed source of replacement water is fully consumable water leased from the City of Aurora. The Applicant has an agreement with the City of Aurora ("Aurora") whereby Aurora will continue to make releases of reusable effluent up to a maximum volume of 249 acre-feet for the Lafarge SWSPs. The applicant will account for a transit loss of 0.5% per mile from the Metropolitan Waste Water Treatment Plant to the gravel pit sites. The transit losses for each site are shown in the table below. For purposes of the SWSP request, an average 5% transit loss was used, which is conservative given the estimated depletions at each site. Point of Replacement Distance From Replacement Source (mi Transit Loss From Replacement Source (% Howe Pit 7 3.5% Mann Lakes 8 4% Ft. Lupton Pit 19 9.5% Lupton Lakes, 14 7% The total lagged mining depletions and replacements are shown on attached Table no. 2. Conditions of Approval I hereby approve this substitute water supply plan, in accordance with Section 37-90-137(11), C.R.S., subject to the following conditions: 1. This SWSP shall be valid for the period of November 1, 2009 through October 31, 2010, unless otherwise revoked, modified, or superceded by decree. If this plan will not be made absolute by a water court action by the plan's expiration date, a renewal request must be submitted to this office with the statutory fee (currently $257 per site) by August 31, 2010.