2018-03-20_REVISION - M2008082 - Laserfiche WebLink

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• September 2017- RMCC asks BBA to prepare the impact report even though A&W has not supplied the well information. • October 2017- BBA completes a draft impact report based on estimated well information. The draft report concludes that the A&W well can sustain a drawdown of 28 feet below ground surface. The report recommends the possible need to evaluate mitigation alternatives when the water level, by reference to water levels in the adjacent monitoring well, reach 20 feet below ground surface. RMCC measures the water level in the monitoring well throughout this period (starting May 2017 to present). The water level in the monitoring well has never reached the 20-foot mark. • January 4, 2018—RMCC provides ground water level data from monitoring well to A&W that indicates a four-foot drop in groundwater level occurred at the monitoring well (which is located near the A&W well)for the period May 2017—January 2018. In addition to mine stage dewatering, RMCC notes low flows in the South Platte River and near-by irrigation ditches confirm that this is the annual low-point in local hydrology. RMCC reiterates its request for well information from A&W. RMCC acknowledges that the monitoring well data should have been sent to A&W earlier in time. • January 11, 2018—Despite A&W's failure to provide well information in response to ongoing requests from BBA, BBA finalizes the impact report. BBA concludes that the A&W well might experience a water level change of as much as 11.5 feet because of dewatering at Stages 6B and 6A(6A is located immediately south of 66). BBA also determines that lining these mine stages after mining as called for in the reclamation plan would only nominally affect A&W's well (less than 0.2 feet). • February 12-23, 2018—Following several telephone calls among RMCC, BBA and A&W, A&W agrees to allow BBA to conduct a pump test on A&W's well at RMCC's sole expense. As part of the pump test and related investigation, BBA determines the total depth of the well is 39 feet,the pump is set at 31 feet,the pump is improperly valved to pump at 700 gpm,the pump cavitated at pumping rates of 400 gpm or greater, and that the well can be operated at a projected long-term pumping rate of 312 gpm. BBA concludes that this pumping rate will deliver water in excess of the weekly and annual volumetric amounts of water A&W is allowed under the DWR Permit No. 61793-F. • March 2018—RMCC has completed mining at Stage 6B and is in the process of partially filling the stage with water to raise the water level in A&W's well (even though the February 2018 pump test confirms A&W can currently produce water at levels higher than allowed in DWR Permit No. 61793-F). RMCC has filed to amend its SWSP to address the additional evaporative loss of ground water that will result from partially filling Stage 6B. RMCC has 2