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Cheryl Signs, P.E. Durham Combined SWSP April 15, 2013 Page 2 of sand and gravel, regardless of whether open mining operations 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 59.6 acres (44.6 acres exposed prior to January 1, 1981 and 15.0 exposed after December 31, 1980) of ground water currently exposed at the Durham Pit site, replacement of evaporative depletions is only required for the 15.0 acres exposed after December 31, 1980. The area exposed prior to 1981 is shown on the attached map (outlined in purple and numbered 1 through 11). The exception to the requirement to replace evaporative depletions for the pre -1981 area is tied to the location identified on the map and may not be applied to other areas of ground water exposure within the gravel pit permit boundary. Although some of the pre -1981 ponds identified in the map are currently dry because of the dewatering operations at the site, if the dewatering stops the original pre -1981 ponds will fill, once filled the pre -1981 area will be consistent with the attached map. You have provided a monthly breakdown of the annual depletions made up of 37.84 acre -feet per year of net evaporative loss, 20.60 acre -feet per year of water lost with the mined product (which represents 700,000 tons of mined product), 2.76 acre -feet per year of water used for dust control, and 3.50 acre -feet per year used for concrete batching. In previous SWSP approvals, phreatophyte credit for pasture grass was credited to this plan, which was based on the 6 -feet depth to ground water, pending better site - specific information. The Applicant was required to provide site - specific information regarding the depth to the ground water table at this location. You indicated that no credit for phreatophyte is claimed in this SWSP until the depth to the ground water can be established. Therefore for the purpose of this SWSP the net evaporation from the 15.0 acres was determined based on an effective precipitation credit of 70 percent from the average precipitation and does not use any phreatophyte credit as shown on Table 1 Column (10). Computation of evaporation under this plan was also reduced during the ice covered period. You have assumed the ice covered period to occur during the months of January and December, based on the average temperatures of 26.0 °F for January and 27.4 °F for December; taken from the Greeley weather station (053533). However, for the purpose of this SWSP, the Applicant shall replace the net evaporation depletions from the exposed ground water surface area that may occur during the assumed ice covered period (the months of January and December) for any time that the pit is not completely covered by ice. Computation of the net evaporation during any time that the pit is not completely covered by ice shall be determined as the pro -rata amount of the monthly gross evaporation rate distribution amount identified in the State Engineer's General Guidelines for Substitute Supply Plans for Sand and Gravel Pits, subtracting the pro -rata amount of the effective precipitation for that period. Operational losses at the Durham Pit also include the Feit Well (Permit No. 76867 -F, WDID 0304999) which is used for the concrete batch plant owned by VCI, but located on the Feit Gravel Pit site. It is projected that 3.23 acre -feet per year will be used in batch plant operations which include an allowance of 0.01 acre -feet per month for domestic use. The monthly depletions of the Durham Pit and the Feit Well are included in "Table I Durham Pit Mining Year Net Depletions" and "Table 1 Feit Well Demand." Dakolios Pit In accordance with the August 3, 2011 SWSP Amendment, this SWSP covers the evaporation of an unlined ground water pond at the Dakolios Pit. This pond is adjacent to the two lined reservoirs used as a replacement supply under this SWSP. The previous SWSP included losses associated with a 3 -acre pond. Recent aerials have shown this pond has partially been backfilled and is now only 1- acre in size. The net evaporation depletion from the 1 -acre pond is 2.55 acre -feet per year.