2010-12-01_HYDROLOGY - M1977036 - Laserfiche WebLink

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Mr. Jared Dains Greeley (35th Avenue) Pit-M77-036 November 23, 2010 Page 2 continued or were reactivated on or after that date. The Water Court effectively held that Senate Bill 120 of 1989, as amended in Senate Bill 93-260, exempted all pre-1981 exposed ground water regardless of whether open mining operations continued or were reactivated on or after January 1, 1981. Accordingly, for the 82.1 acres (52 acres exposed prior to January 1, 1981 and 30.1 exposed after December 31, 1980) of ground water currently exposed at the Greeley 35th Avenue Pit, replacement of evaporative depletions is only required from the 30.1 acres exposed after December 31, 1980. The area exposed prior to 1981 is shown on the attached map. The credits for the pre-1981 area are tied to the location identified on the map and may no longer be re-allocated to other areas of ground water exposure within the gravel pit permit boundary. The anticipated net depletion for this SWSP is 117.50 acre-feet per year. You have provided a monthly breakdown of the annual depletions totaling 87.94 acre-feet of evaporative loss, 14.72 acre-feet of water lost with mined product associated with 500,000 tons of aggregate, 6 acre-feet of water used for dust control and 8.84 acre-feet of water used in concrete production to be appropriated from the well permit no. 47856-F (WDID 0307597). Lafarge filed for water storage right for this site in Case no. 98CW476. The site has been continuously dewatered at a rate of approximately 1200 gallons per minute. The . Greeley 35th Avenue Pit is located approximately 250 feet from the Cache La Poudre River, thus depletions were not assumed to be instantaneous and have been lagged back to the Cache La Poudre River. A stream depletion model using the Glover method was used to calculate the lagged depletions to the Cache La Poudre River. The following parameters were used in the model: transmissivity (T) = 120,000 gallons per day per foot, specific yield (SY) = 0.2, the distance from the Cache La Poudre River to the edge of the alluvium = 5,000 feet, and the distance from the edge of the exposed surface water areas to the Cache La Poudre River = 250 feet. The total lagged mining depletions during the SWSP period are 116.15 acre-feet. The total lagged depletions include the 8.84. acre-feet used for concrete production from well permit no. 47856-F and 107.31 acre-feet from the other consumptive uses at the site. According to the Applicant, the distance from the surface of the exposed ground water area to the Cache La Poudre River was measured based on the down gradient extent of the exposed ground water surface (nearest point). For purposes of this SWSP, the method used to measure the distance to estimate the lagged depletions will be accepted, however any future SWSP must measure the distance from the exposed ground water surface area to the Cache La Poudre River based on the centroid of the exposed ground water surface. Replacements The source of replacement water will be from a lease 125 acre-feet of fully consumable effluent water from the City of Greeley ("Greeley"). Lafarge traded its 550 Boyd and Freeman Ditch shares for 125 acre-feet of augmentation water from Greeley. Fully consumable replacement water is to be provided by Greeley and it will be returned to the river at one of the following locations: a) Greeley Water Pollution Control Facility Outfall (WDID 0302312) located on the Cache La Poudre River; b) JBS Swift Industrial WWTP Outfall (WDID 0102342) on Lone Tree Creek; c) confluence of the 3e Avenue Drainage Ditch and Cache La Poudre River or any 41 y,