2014-06-18_HYDROLOGY - M1977439 - Laserfiche WebLink

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Upper Poudre Combined SWSP Page 4 of 10 June 18, 2014 of the mined material by weight, and the water retained in the washed product is considered to be 4.0% of the mined material by weight. The Alluvial Water Accounting System (AWAS), which uses the Glover method, was used to determine the lagged depletions to the Cache La Poudre River from past and projected evaporation and operational losses at each site. The following parameters were used in the model with the alluvial aquifer boundary condition: the distance (X) from the centroid of the exposed ground water surface to the river; the width (W) of the aquifer on the side of the river where the pit is located; the transmissivity (T); and the specific yield (S). The Glover parameters used for each site are shown in Table C below. Table C - Glover Parameters Site Name X (ft) W(ft) T (gpd/ft) S Home Office Pit 1,000 6,500 160,000 0.2 Overland Ponds Pit 2,000 3,000 160,000 0.2 North Taft Hill Expansion Site 1,600 2,900 160,000 0.2 The estimated consumptive use and lagged stream depletions due to past and projected evaporation and operational losses at the subject sites will total 110.15 acre-feet for this plan period as shown on the attached Table 5. Lagged depletions due to past evaporation and operations at the two Treiber Lakes and three Lamb Lakes are replaced under the Partners Combined SWSP. The three sites are assumed to have been continuously dewatered and to be in a steady state condition where dewatering accretions equal the lagged depletions. The former site operator, Lafarge West, Inc., previously estimated that the sites are dewatered at a rate of 800 to 1,000 gpm for approximately 12 hours per day. Based on information previously provided to this office, all dewatering is directed to the Overland Ponds site where a single pump then directs water to the river. During 2012, MMM installed a totalizing flow meter on this pump and will report monthly meter readings on submitted accounting. As long as the dewatering operations are constant the site may continue to operate assuming steady state conditions. Once dewatering ceases or is reduced in its flow, lagged depletions will immediately hit the river. At least three years prior to a modification in dewatering operations, the Applicant must provide a plan showing how tagged post-pumping depletions will be replaced in the proper time and amount. The post pumping analysis shall use the meter data from the dewatering totalizing flow meter. Replacements Replacements for this combined plan will come from credits associated with 7.61 out of 15.175 shares owned by MMM in the Taylor Et Gill Ditch. In the event that the yield from the 7.61 shares is less than projected, MMM may supplement their replacement supplies with other sources, subject to the Division Engineer's approval. This SWSP relies on a quantification of average historical farm headgate delivery, consumptive use, and associated return flow approved in previous SWSPs based on an analysis for 5.75 shares that was performed for Lafarge West, Inc. by the Applegate Group, Inc. The 5.75 shares were determined to have been used to irrigate a total of 104.5 acres. The historic average farm headgate delivery was determined to be 41.79 acre-feet per share (2.30 acre-feet per irrigated acre). The historic consumptive use was determined to be 21.36 acre-feet per share (1.17 acre-feet per acre). For 2014, the Applicant proposes to dry-up, or to irrigate exclusively with non-Taylor Et Gill Ditch water, a total of 138.34 acres associated with the subject 7.61 shares. The location of the lands to be dried up for the 2014 irrigation season are shown on the attached Figure 2 (65.43 + 14.36 + 2.67 + 55.88 = 138.34 acres). The dry-up will provide a total of 318.12 acre-feet of farm headgate delivery or 162.55