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Upper Poudre Combined SWSP Page 3 of 10 <br /> June 18, 2014 <br /> for areas whose reallocation was approved by the State Engineer prior to January 1, 2011. Previous <br /> SWSPs (prior to January 1, 2011) approved the pre-81 area without specific mention of its location. <br /> Therefore, the State Engineer's Office allowed the pre-81 area to be re-allocated and memorialized <br /> under the May 11, 2011 SWSP approval. The applicant provided a map (Figure 1 - Home Office Pit) <br /> showing the specific location of the pre-81 area (including the 22.1 acres of ground water exposed in <br /> Lamb Lake A). The credits for the pre-81 area are tied to the location identified on Figure 1 - Home <br /> Office Pit and may not be re-allocated to other areas of ground water exposure within the gravel pit <br /> boundary. <br /> Evaporative depletions were calculated using a gross annual evaporation of 38 inches, with a <br /> credit of 10.56 inches for effective precipitation (based on an average annual precipitation of 15.08 <br /> inches for the Fort Collins weather station, 053005). You have estimated that there are a total of <br /> 240.9 acres of exposed ground water surface within the permit boundary of the Home Office Pit. Of <br /> this amount, 100 acres are considered to be pre-81 and do not require replacement and 125.2 acres <br /> are included in the Partners Combined SWSP (note that this amount includes 37.8 acres associated <br /> with Treiber Pond A, which has been lined), leaving depletions from 15.7 acres which must be <br /> replaced under this SWSP. You have estimated the total surface area of ground water exposed in the <br /> North Taft Hilt Expansion Site as 7.52 acres for this plan period. You have estimated the total <br /> surface area of ground water exposed in the Overland Ponds Site as 0.43 acres from January 1, 2014 <br /> through July 31, 2014, and zero (0) acres for the remainder of the plan period. You have assumed <br /> that no ground water will be exposed in cell 3 after construction of the slurry wall by August 1, 2014. <br /> As previously noted, any water exposed within the lined perimeters of cells 3-5 must be treated as <br /> ground water with evaporation losses assessed until the liners for the subject cells are approved by <br /> this office. in addition, lagged depletions resulting from exposure of ground water in cell 3 prior to <br /> construction of the slurry wall and approval of the liner by the State Engineer's Office must continue <br /> to be replaced under this SWSP. <br /> The estimate of evaporative losses under this combined plan was reduced during the ice <br /> covered period. You have assumed the ice covered period occurs from December through February, <br /> based on the average temperatures of 29.04°F for December, 27.59°F for January and 30.61°F for <br /> February; taken from the Fort Collins weather station (053005) using available data for the period of <br /> 1893-2012. The ice covered periods may be used to reduce the amount of evaporative losses that <br /> need to be replaced; however, for the purpose of this SWSP, the Applicant shall replace the net <br /> evaporation depletions from the exposed ground water surface area that may occur during the <br /> assumed ice covered period (January, February, and December 2014) for any time that the pits are <br /> not completely covered by ice. Computation of the net evaporation during any time that the pits are <br /> not completely covered by ice shall be determined as the pro-rata amount of the monthly gross <br /> evaporation rate distribution amount identified in the State Engineer's General Guidelines for <br /> Substitute Supply Plans for Sand and Gravel Pits, subtracting the pro-rata amount of the effective <br /> precipitation for that period. <br /> You have estimated that a total of 38.59 acre-feet of water will be pumped from the Home <br /> Office Pit and used for dust control purposes at either the Home Office Pit or Overland Ponds sites <br /> during this plan period. All water used for dust suppression at the Overland Ponds Site is projected <br /> to be supplied from the Home Office Pit, and no water is anticipated to be used for dust control <br /> purposes at the North Taft Hill Expansion Site. Water pumped for dust control purposes is considered <br /> to be 100% consumed. All pumping for dust control purposes must be metered. <br /> You have estimated that a total of 995,500 tons of aggregate will be mined at the Overland <br /> Ponds site during this plan period. Of this amount, 317,185 tons is anticipated to be crushed and <br /> 678,315 tons is anticipated to be washed. The material is mined below the ground water table, but <br /> in a dewatered state, therefore the water retained in the crushed product is considered to be 2.0% <br />