2009-12-14_HYDROLOGY - M2001107 - Laserfiche WebLink

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;r Michelle L. Hatcher December 14, 2009 Page 2 Depletions The anticipated consumptive use for this plan is 29.01 acre -feet per year (Table 4) for up to 2.73 acres of ' exposed water surface. You have provided a monthly breakdown of the maximum annual consumptive use totaling 8.09 acre -feet of evaporative loss from a maximum of 2.73 acres of exposed groundwater, 6.20 acre -feet for dust control and 14.72 acre -feet of water lost with 500,000 tons of mined product. The pit is located greater than 100 feet from the South Platte River and the resulting depletions have been lagged to account for the delayed effects on the river system. The IDS AWAS stream depletion model was used to determine the lagged depletions to the South Platte River. The following parameters were used in the model: transmissivity (T) = 150,000 gallons per day per foot, specific yield (SY) = 0.2, the distance from the South Platte River to the edge of the alluvium = 5,000 feet, and the distance from the centroid of the exposed surface water areas to the South Platte River is approximately 3,300 feet. Replacements The source of replacement water is fully consumable water leased from Thornton. The leased water from Thornton will be released from the _Metropolitan Wastewater Treatment Plant ( "Metro "). A 0.5% per mile transit loss (14% overall loss for the 28 miles between Metro and the point of depletion) was accounted for in the SWSP. Thornton has purchased the NCCI Pit #1 site, thus will continue to make replacement for depletions at the NCCI Pit #1 site. The lagged depletions include depletions resulting from past uses at the site, and the replacements are shown on attached Table 5. Conditions of Approval I hereby approve the proposed substitute water supply plan in accordance with Section 37 -90- 137(11), C.R.S., subject to the following conditions: 1. This SWSP shall be valid for the period of January 1, 2010 through December 31, 2010, unless otherwise revoked, modified, or superceded by decree. If this plan will not be made absolute by a water court action by the plan's expiration date, a renewal request must be submitted to this office with the statutory fee by November 15, 2010. 2. Well permit no. -F was obtained for the current use and exposed pond surface area of the gravel pit pond in accordance with §37 -90- 137(2) and (11), C.R.S. 3. The total surface area of the groundwater exposed at the NCCI Pit #1 Pit must not exceed 2.73 acres (in the dewatering trenches and ponds) during the approval period of this SWSP resulting in an annual evaporative loss of 8.09 acre -feet. 3. The annual amount of water used at the operation shall not exceed 6.2 acre -feet for dust control and the total product mined shall not exceed 500,000 tons per year below the groundwater surface resulting in 14.72 acre -feet of water lost with the product. 4. Total consumption at the NCCI Pit #1 Pit must not exceed the aforementioned amounts unless an amendment is made to this plan.