2014-06-20_HYDROLOGY - M1983090 - Laserfiche WebLink

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Poudre Pits Combined SWSP Page 2 of 9 June 18, 2014 portion of the site and all depletions from the Firestein and Tigges parcels will be covered under this SWSP. The La Poudre site consists of three separate ponds designated as the West Lake, Middle Lake, and East Lake. All aggregate within the La Poudre Pit has previously been mined, and no mining is planned for the site during this plan period. There is currently no mining planned for the adjacent North La Poudre site; however, mining of a small amount of aggregate may occur at the site during this plan period and is accounted for in this SW S P. The North La Poudre site will be continuously dewatered in order to keep the ground water level below the backfilled pond on the west portion of the site. Depletions Evaporation and Operational Losses During this SWSP period, depletions will consist of evaporation losses and production depletions at the Firestein/Tigges, La Poudre, and North La Poudre Pits. The depletions for each site are shown in the following table: Table B - 2014 Site Depletions (acre-feet)* Water Lost Water Consumed Site Name Evaporation in Mined in Concrete Dust Total Total Lagged Losses Product Batching Control Depletions Depletions Firestein/Tigges 125.33 4.41 9.61 1.68 141.04 137.08 La Poudre 75.76 North La Poudre 14.29 1.47 6.41 2.20 100.13 90.99 Total 215.38 5.88 16.02 3.88 241.17 228.07 *Depletions shown do not include those from past or projected dewatering operations at the sites. For the purposes of this SWSP, depletions are assumed to impact the Cache la Poudre River perpendicular to the point of depletions, which is considered to be the centroid of the exposed surface area at each site. Evaporative depletions for each site were calculated using a gross annual evaporation of 38.5 inches, with a credit of 9.78 inches for effective precipitation (based on an average annual precipitation of 13.97 inches for the Windsor weather station). Operational losses at the Firestein/Tigges site will consist of 1.68 acre-feet of water for dust control, 9.61 acre-feet of water for the production of 75,000 cubic yards of concrete (assumes 40 gallons of water per cubic yard of concrete), and 4.41 acre-feet of water lost with 150,000 tons of aggregate. The aggregate is mined below the water table and is washed; therefore the water retained in the mined product is considered to be 4.0% of the mined material by weight. Depletions from the Firestein/Tigges site will impact the Cache la Poudre River upstream of the Greeley No. 3 Ditch (W DI D 0300934). As noted above, no mining is planned for the La Poudre and North La Poudre Pits during this SW S P period; however, to be conservative the mining of up to 50,000 tons of aggregate at the sites has been included in this plan. Operational losses at the La Poudre and North La Poudre sites will consist of 2.20 acre-feet of water for dust control, 6.41 acre-feet of water for the production of 50,000 50,000 cubic yards of concrete, and 1.47 acre-feet of water lost with 50,000 tons of aggregate. Water