Laserfiche WebLink
Jared Dains Page 4 <br />February 3, 2011 <br />The mining sites are set back from the river, therefore, the depletions from the operations were <br />not assumed to be instantaneous. Operational and evaporative depletions at the site were lagged to <br />the stream system using a Glover analysis and the aquifer parameters shown below: <br />Site Name X ft W ft T d/ft Specific Yield <br />Howe Pit 350 12,000 45,000 0.2 <br />Mann Lakes 400 4,450 45,000 0.2 <br />Riverbend Operation Stream Dep letion Factor of 300 days was used <br />Lupton Lakes 3,100 7,000 150,000 0.2 <br />X-distance from well to river <br />W-distance from the aquifer boundary through the well to the river channel <br />T-transmissivity of the alluvial aquifer (in gallons per foot/day) between the well and the river <br />For the purposes of this SWSP, the distance of the exposed ground water to the river <br />(" X") is accepted; however, should the Applicant seek to renew this SWSP, the Applicant must <br />calculate the depletions with the X value measured from the centroid of the ground water pond. <br />The lagged mining depletions are shown on attached Table 1. <br />Replacements <br />The proposed source of replacement water is fully consumable water leased from the City of <br />Aurora. The Applicant has an agreement with the City of Aurora ("Aurora") whereby Aurora will <br />continue to make releases of reusable effluent up to a maximum volume of 249 acre-feet for the <br />Lafarge SWSPs. The applicant will account for a transit loss of 0.5% per mile from the Metropolitan <br />Waste Water Treatment Plant (WDID 0200700) to the gravel pit sites. The transit losses for each site <br />are shown in the table below. For purposes of the SWSP request, an average 5% transit loss was <br />used, which is conservative given the estimated depletions at each site. <br />Point of <br />Replacement Distance From <br />Replacement Source mi Transit Loss From Replacement Source <br />Howe Pit 7 3.5% <br />Mann Lakes 8 4% <br />Riverbend Operation 19 9.5% <br />Lupton Lakes 14 7% <br />For the purpose of this SWSP the proposed transit loss is accepted however, the transit <br />loss is subject to change if the division engineer and the water commissioner determines that a <br />different transit loss needs to be assessed to the Aurora leased water. <br />The total lagged mining depletions and replacements are shown on attached Table 2. <br />Conditions of Approval <br />I hereby approve this substitute water supply plan, in accordance with Section 37-90-137(11), <br />C.R.S., subject to the following conditions: