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Ms. Michelle L. Hatcher <br />March 7, 2011 <br />Page 2 of 6 <br />will need to provide additional documentation to this office that specifies what water <br />rights or other permanent water source will be dedicated to the SWSP to assure that all <br />permanent depletions from either an unforeseen abandonment of the site by the <br />Applicant or as a result of long term ground water exposure after completion of mining <br />and .reclamation will be replaced so as to prevent injury to other water rights. <br />This information must be provided to this office by April 30, 2011. If the requested <br />information is not provided to the Division of Water Resources, any future SWSP may <br />limit the mining operation so that additional ground water cannot be exposed, beyond <br />that specified in this SWSP. <br />Depletions <br />The County has completed mining in all the cells except the southeastern cell of the <br />mining site. During the period of this plan, the County anticipates the total exposed surface area <br />in this cell will be approximately 13.1 acres. There are 31.6 acres of ground water exposed in <br />the previously mined areas; therefore the total exposed surface area at this site will be 44.7 <br />acres. <br />According to the information submitted, 4.1 acres of ground water surface was exposed <br />to the atmosphere within the reclamation permit boundary prior to January 1, 1981. Based on <br />the Division 1 Water Court decision in case no. 2009CW49, the replacement of evaporative <br />depletions is not required for ground water exposed to the atmosphere prior to January 1, 1981 <br />through open mining of sand and gravel, regardless of whether open mining operations <br />continued or were reactivated on or after that date. The Water Court effectively held that Senate <br />Bill 120 of 1989, as amended in Senate Bill 93-260, exempted all pre-1981 exposed ground <br />water regardless of whether open mining operations continued or were reactivated on or after <br />January 1, 1981. Accordingly, for the 44.7 acres of ground water currently exposed at the <br />Geisert Pit, replacement of evaporative depletions is only required for the 40.6 acres exposed <br />after December 31, 1980. The area exposed prior to January 1, 1981 is shown on the <br />attached Figure 1. The exception to the requirement to replace evaporative depletions <br />for the pre-1981 area is tied to the location identified on Figure 1 and may not be applied <br />to other areas of ground water exposure within the gravel pit permit boundary. <br />Net evaporative depletions were calculated using a gross annual evaporation of 45 <br />inches from the exposed water surface, with a credit of 9.87 inches for effective precipitation. <br />No phreatophyte credit has been applied to this plan. The net depletion of ground water due to <br />evaporation from the 40.6 acres ground water exposed at the site after December 31, 1980 was <br />calculated to be 118.9 acre-feet. <br />Weld County anticipates that 150,000 tons of gravel will be mined during this plan <br />period. The material is mined below the water table and is not washed; therefore the water <br />retained in the mined product is considered to be 4.0% of the mined material by weight, which <br />equals 4.4 acre-feet. <br />Ground water from the pits will not be used for dust control at the site. Instead, water for <br />this purpose will be provided from Weld County Dust Control Well #1 (permit no. 50426-F, <br />WDID 0305714), which operates under a separate SWSP (WDID 0302567). <br />Water consumed by the mining operation will also include water removed from the