Laserfiche WebLink
Jeff Clark Page 3 <br /> Bromley Lakes SWSP <br /> February 10, 2016 <br /> Some mining will occur above the ground water surface and some will occur below the ground <br /> water surface. For gravel mining within the Kenneth Mitchell Lake 1 slurry wall, or above the static <br /> ground water table in Bromley Cell 2, a 2% water loss by weight has been charged for the wash <br /> product. For Bromley Lot 2 projected mining is assumed to be below the ground water surface and <br /> has been charged 4% water loss by weight. For the period of this SWSP, RMCC projects 824,000 tons <br /> of gravel production at this site (150,000 tons at Bromley Cell 1 and 674,000 tons for Bromley Lot 2). <br /> The gravel production depletions are projected to be a maximum water loss of 2.2 acre-feet for <br /> Bromley Cell 1 and 19.8 acre-feet for Bromley Lot 2. <br /> RMCC continues to dewater Bromley Lot 2. The dewatering pumping rate is expected to be <br /> less than or equal to 5.0 acre-feet per day. <br /> The total consumptive use at this site for the period of this SWSP is 111.8 acre-feet. These <br /> depletions do not hit the river instantaneously and thus must be lagged back to the river. As <br /> described in the previous SWSP approvals the depletions are lagged to the South Platte River and the <br /> McCanne Ditch. With the approval of the liner for Bromley Cell 3/Lot 1, the Applicant has separated <br /> the lagging analysis for the Bromley Lot 2, which are located east of the McCanne Ditch, with the <br /> lined gravel pit expected to block most of the depletions from impacting the South Platte River. <br /> Therefore, for the Bromley Lot 2, the Applicant performed a lagging analysis to the McCanne Ditch, <br /> which flows year round and discharges to the South Platte River. The Glover parameters applied for <br /> the Bromley Lot 2 are as follows: <br /> • specific yield = 0.2 <br /> • transmissivity = 100,000 gpd/ft <br /> • distance from centroid of mining area to McCanne Ditch = 600 feet <br /> • distance from McCanne Ditch to alluvial boundary = 3,500 feet <br /> The depletions from Bromley Cell 2 occur west of the McCanne Ditch and are tagged to the South <br /> Platte River using the following Glover parameters: <br /> • specific yield = 0.2; <br /> • distance from the stream to the alluvial boundary = 5,300 feet <br /> • transmissivity = 100,000 gallons per day per foot; <br /> • distance from the centroid of the exposed ground water to the stream = 1,016 feet. <br /> The distance to the alluvial boundary is based on the Applicant's analysis of geologic cross <br /> sections showing that the alluvium is pinched at approximately the railroad east of the site. <br /> The Applicant wrapped the remaining 5% tail of the depletions into the previous months. The <br /> depletions factors for the areas west and east of the McCanne Ditch are shown in the following table: <br /> Bromley Site Depletion Factors <br /> Month Bromley Cell 2 Bromley Lot 2 <br /> 1 0.4529 0.6415 <br /> 2 0.2696 0.2183 <br /> 3 0.0755 0.0677 <br /> 4 0.0454 0.0436 <br /> 5 0.0345 0.0289 <br />