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Upper Poudre Combined SWSP Page 4 of <br /> January 28, 2016 <br /> You have estimated that a total of 29.00 acre-feet of water will be pumped from the Curry <br /> Pit at the Home Office Site for dust control purposes, but may periodically come from the North Taft <br /> Hill Expansion Site during this plan period. Water pumped for dust control purposes is considered to <br /> be 100% consumed. All pumping for dust control purposes must be metered. <br /> You have estimated that 848,000 tons of aggregate will be mined at the North Taft Hill <br /> Expansion Site during this plan period. Of this amount, 350,700 tons is anticipated to be crushed and <br /> 497,300 tons is anticipated to be washed. You have estimated that an additional 59,000 tons of <br /> aggregate will be mined at the Home Office Pit Site in December 2016, of which 29,500 tons is <br /> anticipated to be crushed and 29,500 tons is anticipated to be washed. The material is mined below <br /> the ground water table, but in a dewatered state, therefore the water retained in the crushed <br /> product is considered to be 2.0% of the mined material by weight, and the water retained in the <br /> washed product is considered to be 4.0% of the mined material by weight. <br /> The Alluvial Water Accounting System (AWAS), which uses the Glover method, was used to <br /> determine the lagged depletions to the Cache la Poudre River from past and projected evaporation <br /> and operational losses at each site. The following parameters were used in the model with the <br /> alluvial aquifer boundary condition: the distance (X) from the centroid of the exposed ground water <br /> surface to the river; the width (W) of the aquifer on the side of the river where the pit is located; <br /> the transmissivity (T); and the specific yield (S). The Glover parameters used for each site are shown <br /> in Table C below. <br /> Table C - Glover Parameters <br /> Site Name X (ft) W (ft) T (gpd/ft) S <br /> Home Office Pit (Curry Pit) 1,000 6,500 160,000 0.2 <br /> Home Office Pit (area to be mined) 1,675 4,675 160,000 0.2 <br /> Overland Ponds Pit 2,000 3,000 160,000 0.2 <br /> North Taft Hill Expansion Site Pit 1,600 2,900 160,000 0.2 <br /> The estimated consumptive use and lagged stream depletions due to past and projected <br /> evaporation and operational losses at the subject sites will total 88.51 acre-feet for this plan period <br /> as shown on the attached Table 5. Lagged depletions due to past evaporation and operations at the <br /> two Treiber Lakes and three Lamb Lakes are replaced under the Partners Combined SWSP. <br /> Dewatering <br /> The Home Office Pit will be dewatered prior to mining and continued throughout the <br /> remainder of this SWSP. <br /> The North Taft Hill Expansion Site will be continuously dewatered throughout this plan period. <br /> For the purposes of this SWSP, you have assumed the site to be in a steady state condition where <br /> dewatering accretions equal the lagged depletions. All dewatering from the North Taft Hill <br /> Expansion Site and Home Office pit site will be pumped to the unlined pre-81 ponds just south of <br /> each site. The ponds have the ability to overflow directly to the Cache la Poudre River. A totalizing <br /> flow meter has been installed on the pump and monthly meter readings are reported on the <br /> submitted accounting for this plan. All water spilled from the ponds is also metered. As long as the <br /> dewatering operations are constant the North Taft Hill Expansion Site and Home Office Pit site may <br /> continue to operate assuming steady state conditions. Once dewatering ceases or is reduced in its <br /> flow, lagged depletions will impact the river. At least three years prior to a modification in <br /> dewatering operations, the Applicant must provide a plan showing how lagged post-pumping <br /> depletions will be replaced in the proper time and amount. The post pumping analysis shall use the <br /> meter data from the dewatering totalizing flow meter. All cells of the Overland Ponds Site were <br /> fully lined, therefore dewatering at the site has ceased. <br />