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Todd Williams Wagner /Kaufmann # 3 SWSP April 4, 2012 Page 2 Pit (DRMS M- 1978 -327, WDID 0403009). The Kauffman #1 Pit is covered under a separate SWSP (WDID 0402530) and is owned and operated by the Applicant. The exposed ground water in Kauffman # 1 Pit was exposed prior to 1981 in connection with sand and gravel mining and as such evaporation from this pit is not required to be augmented (see § 37- 90- 137(11)(b), C.R.S. & 09CW49). The dewatering pump discharges into the Kauffman #1 Pit at a location approximately 100 feet from the intake of W -K #3. Water discharged into the Kauffman # 1 Pit will recharge ground water because the pit is unlined and, given the large size of the pit, the additional volume attributable to the dewatering flows does not create a measureable increase in evaporation. Both pits are immediately adjacent to each other and similarly situated along the Big Thompson River. Thus the parameters used to model the lagged depletions are the same parameters used to model the lagged accretions. Additionally all of the dewatering flows have been discharged into the Kauffman #1 Pit. With this understanding, it can be assumed that the dewatering operation, as it has existed since 2000, has created lagged accretions that mimic the lagged depletions. Therefore, the SWSP is approved on the basis that there will be no net depletions as a result of dewatering flow reduction or complete cessation. Long Term Depletions In accordance with the letter dated April 30, 2010 from the Colorado Division of Reclamation, Mining, and Safety ( "DRMS "), all sand and gravel mining operators must comply with the requirements of the Colorado Reclamation Act and the Mineral Rules and Regulations for the protection of water resources. The April 30, 2010 letter from DRMS requires that you provide information to DRMS to demonstrate you can replace long term injurious stream depletions that result from mining related exposure of ground water. The DRMS letter identifies four approaches to satisfy this requirement. Approach # 3 is to file a financial warranty to cover the cost of installing a liner. Jake Kauffman and Son, Inc holds a bond in the amount of $570,000 to cover the cost of lining and reclamation activities Depletions The exposed ground water surface area is 0.16 acres. Net evaporative depletions were calculated using a gross annual evaporation of 38 inches from the exposed ground water surface, with a credit of 9.5 inches for effective precipitation. The net depletions of ground water due to evaporation from the 0.16 acres at the W -K #3 site totals 0.36 acre -feet per year, as shown on the attached Table 1. There will be neither aggregate production nor other ground water consuming activities at the site during this SWSP approval period. A stream depletion model was used to determine the timing of lagged depletions to the Big Thompson River. The following parameters were used in the stream depletion model for 2012: transmissivity (T) = 50,000 gallons per day per foot, specific yield (SY) = 0.2 (which is typical for an alluvial aquifer), the distance from the centroid of the exposed ground water to the river (X) = 2,400 feet, and the location of the parallel impermeable boundary was estimated to be 4,000 feet from the stream. To be consistent with previous approved SWSPs for this site, lagged depletions caused by mining operations prior to 2012 were determined using the previous approved distance parameter (X) of 200 feet. The total lagged depletions that hit the river during this SWSP approval is 0.90 acre -feet. See Table 5 for these depletions monthly distribution. This amount includes lagged depletions from past years operations. Replacements Replacement water for this pit will continue to be made available throughout the year from a lease with the City of Loveland ( "Loveland ") that allows the Applicant up to 65 acre -feet of fully consumable water. This lease also applies to losses at another gravel pit, Kauffman Pit DRMS M -1978- 327 (SWSP WDID 0402530). A copy of the original lease and the amended 2012 lease request dated •