Laserfiche WebLink
Michelle L. Austin and Daria Giron, P.E. Page 2 <br />May 8, 2006 <br />The proposed replacement source is fully consumable water leased from the City of <br />Arvada ("Arvada")and the St. Vrain Left Hand Water Conservancy District ("SVLH"). If the mine <br />is dewatered and dry mined, water discharged from the pit during dewatering operations that is in <br />excess of the lagged impacts of the dewatering operation itself will be used as a replacement <br />source in this plan. <br />The final reclamation of the pit includes backfilling or lining of all exposed groundwaterwithin <br />the permit boundary. The applicant has bonded for lining and backfilling of the pit as part of their <br />permitting process through the Division of Minerals and Geology. <br />Depletions <br />Ground water is exposed at the site. The ground water exposed at this site is estimated to be <br />24 acres with an annual depletion of 70 acre-feet. All ground water at the site was exposed after <br />December 31, 1980. <br />The remaining uses at the site are water lost in mined product, water used for concrete <br />batching and water used for dust suppression. The plan specifies that 44.2 acre-feet of water will be <br />removed in 1,500,000 tons of mined product, 2.0 acre-feet will be required for dust suppression and <br />15.5 acre-feet will be required for the production of 150,000 cubic yards of concrete. <br />If the pit is dewatered for dry mining, the plan estimates that the ponds will be dewatered at a <br />rate of 1,200 gpm for 8 hours a day, 365 days a year. The depletions resulting from dewatering <br />pumping will be replaced under this plan. <br />The depletions from evaporation, water removed in product, dust suppression and concrete <br />batching were lagged to the stream system using a Glover analysis and assuming a distance to the <br />no flow boundary of 7,603 feet, distance of the well to the river of 2,640 feet, transmissivity of <br />150,000 gpd/ft and specific yield of 0.2. <br />Replacements <br />The proposed source of replacement water for this pit is 127.25 acre-feet of fully <br />consumable effluent leased from Arvada for the period of June 2006 through October 2006 and <br />April 2007 through October 2007 and 30.9 acre-feet of fully consumable water leased from SVLH <br />for the period of November 2006 through March 2007. The Arvada water will be released from <br />Metro Wastewater Treatment plant and a five percent transit loss will be accounted for in the <br />replacement. <br />If the site is dry mined, water discharged from the pit during dewatering operations that is <br />in excess of the lagged impacts of the dewatering operation itself will be used as a replacement <br />source. Prior to claiming credit for the water discharged to the river as part of the dewatering <br />process, the applicant must install adequate measuring devices to allow proper administration. <br />The monthly depletions and replacement requirements are found on the attached Table <br />D. <br />Conditions of Approval <br />As required by Section 8 of Senate Bill 89-120, this substitute water supply plan has been <br />provided to an outside consultant for review. I hereby approve the proposed substitute water <br />supply plan in accordance with §37-90-137(11), C.R.S. subject to the following conditions: <br />