2011-08-23_HYDROLOGY - M1981022 - Laserfiche WebLink

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Mr. Jared Dains G.L. Pit Substitute Water Supply Plan (DRMS# M -81 -022) August 16, 2011 Depletions The only consumptive use associated with the G.L. Pit site will be from evaporation of exposed groundwater. As mentioned above the current exposed surface area at the G.L. Pit is 1.0 acre. Total estimated annual consumptive use for this plan is 1.4 acre -feet of evaporation from 1.0 acre of exposed water surface area which also include a phreatophyte credit. For the 1.0 acre, an evaporative value of 16.76 inches was used. The evaporative depletions from the 1.0 acre is 1.4 acre -feet. The G. L. Pit is located approximately 1700 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. According to the Applicant, the distance from the surface of the exposed ground water area to the stream 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 from the pond to the stream 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. You have provided a monthly breakdown of the annual lagged depletions totaling 1.4 acre - feet of evaporative Toss. The amount of lagged depletions is t.7 acre -feet which include the post - pumping depletions of the area that has been backfilled. Replacement Conditions of Approval Page 2 The proposed source of replacement water for this pit is a lease of fully consumable water from the Tri- Districts. The lease is for the period of June 2011 through May 2012. A copy of the Tri - Districts lease was provided to this office on June 17, 2011 and is attached to this letter. The replacement water will originate from the Divide Canal and Reservoir Company. The Tri- Districts have water stored in low elevation reservoirs to make replacements during all months of the year in coordination with the Poudre River water commissioner. The amount of replacement water leased from the Tri- Districts also includes a 7.8 percent transit loss from the Eaton Reservoir to GL Pit. The transbasin Divide Canal and Reservoir Company water is transported over Boulder Ridge in the Wilson Ditch and stored in the Eaton Reservoir. Releases made from Eaton Reservoir travel approximately 50 miles to the mouth of the Poudre Canyon. The monthly depletions and replacement requirements are found on the attached Table 2. In accordance with the letter dated April 30, 2010 (copy attached) 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. In accordance with approach no. 1 and 3, you have obtained a bond for $148,500 through DRMS for lining of the exposed ground water. I hereby approve the proposed substitute water supply plan in accordance with §37 -90- 137(11), C.R.S., subject to the following conditions: