2008-04-08_HYDROLOGY - M1983090 - Laserfiche WebLink

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Ms. Sara Foster April 8, 2008 The total losses for the sites are shown in the following table: TABLE B -DEPLETIONS Page 6 Water New Evaporatio Product Consumed in Dust Total Pem~it Site Name n Losses Maisture .Loss Concrete Control (ac-ft) Required (ac-ft) (ac-ft) Batching (ac-ft) ,~ ac-ft Firestein~gges/ 8.e"!1 (279,000 9.39 Roberts Pit 94.61 tons of (76,500. 1.66 113.87 No imaterial cubic ards La Poudre Pit 78.13 0 9.39 (76,500 1.66 18 89 No cubic ards . North La Poudre 23.95 0 0 0 23 95 No Pit . Total 196.69 8.21 18.78 3.32 227 The Firestein~gges/Roberts Aggregate Mine is comprised of three adjacent properties; the Firestein, Tigges and Roberts parcels. Based on a March 2005 aerial photo of the Firestein/Tigges/Roberts site, the exposed water surface area totals 39.53 acres, which includes 1.68 acres of dewatering trenches in the Tigges Pit. All pits under active mining are dewatered into the Cache La Poudre River. Mining of the Roberts Pit was completed in May 2006 and the pit has been reclaimed and a plan for augmentation was approved in case no. 2002CW331. The depletions were estimated using the AWAS model using the same aquifer characteristics used to estimate the evaF~orative and operational depletions, except the distances from the exposed ground water to the river for Firestein is 1,034 feet, Roberts is 3,435 feet, and Tigges is 3,600 feet. Based on a March 2005 aerial photo of the La Poudre Pit and North La Poudre Pit sites, there are 32.63 acres of groundwater exposed at the La Poudre site and 10 acres at the North La (Poudre site. Dewatering operations at the La Poudre and North La Poudre sites ceased in 2003. The timing of the lagged depletions from the dewatering operations was determined through a stream depletion model for these two sites. The FiresteinlTigges/Roberts site has been continuously dewatered since 2002. Dewatering of the Roberts Pit has stopped. Dewatering of the Tigges Pit commenced in June 2005. The dewatering rate at the Firestein/Tigges/Roberts site is 250 gallons per minute. The timing of the laggecl depletions from the dewatering operations was determined through a stream depletion model for the Firestein/Tigges/Roberts site. The model addresses the lagged depletions at the La Poudre- and North La Poudre sites by accounting for the net accretion credits at the river that occur due to the dewatering operation at the FiresteinlTigges/Roberts site. These accretions are applied to this plan against depletions from the La Poudre and North La Poudre sites. The attached Table 5 shows a summary of monthly depletions from dewatering. Replacement The proposed source of replacement water for this combined plan is historical consumptive use credits available from 11 shares of the Whitney Ditch, used for the irrigation of 342 aches on the