2015-09-17_HYDROLOGY - M1977559 - Laserfiche WebLink

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Mr. Paul Bruss September 15, 2015 Page 2 of 5 Valco and the District are still in negotiations and it is anticipated that a water court application, and a companion SWSP request, may not be filed for 1-2 years. Accordingly, Valco seeks a 2 -year SWSP approval to finish development of these plans for permanent augmentation. 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 nos. 1 and 3 require bonding to ensure the pit can be backfilled or lined. The 4th approach requires documentation to identify what water rights or other permanent water source will be dedicated to the SWSP to assure that all permanent depletions from either an unforeseen abandonment of the site by the Applicant or as a result of long term ground water exposure after completion of mining and reclamation will be replaced so as to prevent injury to other water rights. While it is the understanding of this office that Valco is in the process of arranging for permanent augmentation coverage, there was no information included with the request to document how Valco is currently in compliance with the April 30, 2010 letter from DRMS. Any SWSP renewal request must contain documentation to show that Valco is currently in compliance with Approach Nos. 1, 3, or 4 of the April 30, 2010 letter from DRMS. DEPLETIONS The Canon City East Pit is presently undergoing reclamation in accordance with the DRMS permit. The only depletions covered under this SWSP are evaporative depletions from onsite gravel pits shown in Figure 1. Evaporative depletions were calculated using the maximum surface area of the pit, which is 22.6 acres (7.2 acres of post -1981 exposed ground water). Therefore, based upon net annual evaporation of 3.1 feet per year, the maximum total annual evaporative depletion will be 22.3 acre-feet (see Table 1, attached). Depletions have been lagged back to the Arkansas River using a Glover analysis with the following parameters: Distance from river: 510 ft Distance from alluvial boundary: 1730 ft Transmissivity: 26,000 gpd/ft Specific yield: 0.2 As shown on the attached Tables 2a-1 and 2a-2, you have calculated the total lagged depletions to be 22.96 acre-feet from June 1, 2015 through May 31, 2016 ("Year 1 ") and 22.32 acre-feet from June 1, 2016 through May 31, 2017 ("Year 2"). /oF' colo 1313 Sherman Street, Room 821, Denver, CO 80203 P 303.866.3581 F 303.866.3589 www.water.state.co.us I rye k oI * 1876