Laserfiche WebLink
Mr. Jared Dains <br />May 11, 2011 <br />Page 3 <br />distribution amount identified in the State Engineer's General Guidelines for Substitute Supply <br />Plans for Sand and Gravel Pits, subtracting the pro-rata amount of the effective precipitation for <br />that period. <br />Based on the Division 1 Water Court decision in case no. 2009CW49, the replacement of <br />evaporative depletions is not required for ground water exposed to the atmosphere prior to January 1, <br />1981 through open mining of sand and gravel, regardless of whether open mining operations continued <br />or were reactivated on or after that date. The Water Court effectively held that Senate Bill 120 of 1989, <br />as amended in Senate Bill 93-260, exempted all pre-1981 exposed ground water regardless of whether <br />open mining operations continued or were reactivated on or after January 1, 1981. Accordingly, for <br />the 240.9 acres (100.0 acres exposed prior to January 1, 1981 and 140.9 exposed after December <br />31, 1980) of ground water currently exposed at the Home Office Pit site, replacement of <br />evaporative depletions is only required from the 140.9 acres exposed after December 31, 1980. <br />You have reported that at the Overland Pond site, all 11.3 acres of exposed ground water were <br />exposed after December 31, 1980, and for the North Taft Hill Expansion site, all 2.3 acres of <br />exposed ground water were exposed after December 31, 1980. The area exposed prior to 1981 <br />at the Home Office Pit is shown on the attached map. The exemption from augmentation <br />requirements for the pre-1981 area is tied to the physical location identified on the map and <br />may no longer be re-allocated to other areas of ground water exposure within the gravel pit <br />permit boundary. <br />A stream depletion model using the Glover method was used to calculate the lagged <br />depletions to the Cache La Poudre River. The alluvial aquifer model uses four aquifer input <br />parameters for each site as follows: 1) X-distance from well to river, 2) W-distance from the aquifer <br />boundary through the well to the river channel, 3) T-transmissivity of the alluvial aquifer (in gallons <br />per foot/day) between the well and the river, and 4) S-specific yield - 0.2 was used for all wells. <br />The following parameters for each site listed in the table below were used in the model: <br />Site Name T X W S <br />Home Office Pit 160,000 300 6,500 0.2 <br />Overland Ponds Pit 160,000 2,000 3,000 0.2 <br />North Taft Hill <br />Ex ansion Site Pit 160,000 1,600 2,900 0.2 <br />According to the Applicant, the distance from the surface of the exposed ground <br />water area for each site to the Cache La Poudre River was measured based on the down <br />gradient extent of the exposed ground water surface (nearest point). For purposes of this <br />SWSP, the method used to measure the distance to estimate the lagged depletions will be <br />accepted, however any future SWSP must measure the distance from the exposed ground <br />water surface area for each site to the Cache La Poudre River based on the centroid of the <br />exposed ground water surface. <br />The estimated monthly consumptive use and lagged stream depletions due to evaporation <br />and operational losses are shown on the attached Table 1.