Laserfiche WebLink
Nathan B. Rand Page 2 <br />October 22, 2010 <br />discharge area be less than the acreages used to compute the maximum depletion; actual <br />depletion will be reduced proportionally. <br />Second, there are sediment detention ponds at the site that, when containing water, will <br />evaporate water. Shown in the table attached are your estimates of maximum monthly <br />depletions from the ponds. Actual depletions will be assessed on any pond that contains a free <br />water surface for more than 72 hours using the monthly evaporation rates given in the table, <br />pond surface area, and number of days the pond contains water. <br />Finally, water is pumped back from an underdrain and spring collection system intended <br />to reduce potential hydraulic head at the base of the mine's engineered liner system. This <br />pumping will be metered and replacements made equal to pumping, in the following month. <br />You have estimated that the depletions from this area of the mine will be 18.46 acre-feet, <br />based on the methodology used in Case No. 02CW122. <br />REPLACEMENT <br />The source of replacement water will be discharge of water purchased from the City of <br />Victor and the City of Colorado Springs. Deliveries of replacement water will be delivered to <br />Arequa Gulch, Wilson Creek or Fourmile Creek on a monthly basis to match replacement <br />requirements. Augmentation stations are shown on Exhibit B (attached). Delivery of <br />replacement water to the Fourmile drainage shall be made so as to match the amount and <br />timing of calculated depletions. <br />Depletions to West Beaver Creek, which are only associated with evaporation losses <br />from detention ponds retaining water after unusually heavy precipitation events, will be made to <br />the Grassy Creek augmentation station (also on Exhibit B). <br />CONDITIONS OF APPROVAL <br />This plan is hereby approved pursuant to Section 37-92-308(4) C.R.S. and the following <br />conditions: <br />1. This plan shall be valid through October 31, 2011, unless otherwise revoked or modified. <br />2. Pumping from the underdrain pump back system must be measured in a manner <br />acceptable to the Division Engineer. <br />3. Accounting of water in this plan, including surface areas of all zero-discharge areas <br />within each drainage zone, identification of all ponds containing water and number of <br />days each pond contains water, pumping from the pump back system, stream <br />depletions, and replacement water deliveries must be provided to the Water <br />Commissioner (Brian Sutton@state.co.us) and Division Engineer <br />(Div2Ground.Water@state.co.us) on forms and at times acceptable to them. Said <br />accounting must be received by the 10th of the month following the month being <br />reported. The name, mailing address, and phone number of the contact person who is <br />responsible for operation and accounting of this plan must be provided on the <br />accounting forms. The Division Engineer may require that any or all measuring devices