2014-02-25_HYDROLOGY - M2001085 - Laserfiche WebLink

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Mr. Craig Lis Page 2 of 5 GSL Sand and Gravel SWSP February 20, 2014 acre -feet for each year of the approval period for this SWSP. The Alluvial Water Accounting System ( "AWAS ") model was used with the alluvial aquifer boundary condition option to lag depletions to the South Platte River. The following parameters were used in the model: transmissivity (T) = 63,000 gallons per day per foot, distance (X) from the surface of the exposed ground water to the river = 2,295 feet, distance (W) from the aquifer boundary through the exposed ground water to the river channel = 3,836 feet, and specific yield (SY) = 0.2. The location of the stream depletion is assumed to be perpendicular to the river. Evaporative and operational losses were considered back to January 1, 2009 because depletions during this time period may still be impacting the river. Lagged depletions during the period of this SWSP are 74.22 acre -feet for 2013- 2014 plan year and 75.41 acre -feet for the 2014 -2015 plan year as shown on the attached Table 4. Replacements The replacement source for this plan period is fully consumable water leased from the City of Aurora ( "Aurora "). The fully consumable water will be released to the South Platte River at the outfall of the Metro Wastewater Reclamation District's Robert W. Hite treatment facility ( "Metro Sewer," WDID 0207000). Metro Sewer is located approximately 11 miles upstream of the site. As such an irrigation season transit loss of 5.5% (0.5% per mile) and a non - irrigation season transit loss of 2.8% (0.25% per mile) will be assessed on all releases. These transit losses are subject to change by the water commissioner or division engineer. The proposed replacement schedule is provided in Table 6. A copy of the signed lease agreement dated April 29, 2013 is attached. Long -term Depletions The final reclamation plan for DRMS Mining Permit No. M- 2001 -085 once had been to create a water storage reservoir through the installation of a slurry wall. The slurry wall was constructed but did not receive its liner approval from DWR. Based on the Applicant's statements, the slurry wall leaked in multiple locations and the pit filled completely with ground water. This was not in accordance with their DRMS permit reclamation requirements. At this time the Applicant has decided to abandon earlier considerations for both (1) repairing the liner and selling the pit as a water storage reservoir (per their original DRMS permit) and (2) pursuing an augmentation plan to cover the long -term depletion requirements, and now plans simply to backfill the pit. The current financial warranty posted for the site is $368,590, which was set by DRMS after approving an amendment request to change the reclamation plan from water storage to an inert backfill operation on the property (to two feet above the water table). This action satisfied the requirement that the Applicant diligently pursue compliance with their DRMS permit and the requirements described in the April 30, 2010 letter DRMS sent to all gravel pit operators (attached), specifically in regard to the required financial warranty at the site. With each successive SWSP renewal request, the Applicant shall demonstrate continued diligence in this effort, including maintaining satisfactory status in obtaining proper bonds through DRMS. Conditions of Approval I hereby approve this 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 November 1, 2013 through October 31, 2015, unless otherwise revoked, modified, or superseded by decree. A SWSP renewal request must be submitted to this office with the statutory fee (currently $257) by August 31, 2015.