Laserfiche WebLink
The majority of springs are located at or above the F Seam outcrop. <br /> A few springs have been identified between the E and F Seam <br /> outcrops. No springs have been identified below the E Seam outcrop. <br /> Monitoring of springs for baseline data and to assess impacts of <br /> mining; in the F Seam has been carried out for the past ten years by <br /> MCC. Evidence to date indicates that mining has very little, if any, <br /> impact on spring flows. <br /> The depth of overburden where the B Seam will be mined in the area <br /> of the springs ranges from 400 to in excess of 1,000 feet. Based on <br /> experience in the F Seam and geotechnical work, the springs will not <br /> be affected significantly by mining in the B Seam under these <br /> overburden depths. <br /> Some inflows to the mine are expected as mining proceeds under Lone <br /> Pine and Gribble Gulches as the valley features are fracture <br /> controlled. Inflows in these areas are estimated from 2 to 20 gpm. It <br /> is anticipated that the flow will be in the middle or lower end of the <br /> range. <br /> If flows into the mine approached the maximum estimated, 20 gpm, <br /> this would only be approximately 14 percent of the peak spring runoff <br /> flow. For this to occur or deplete spring flow, a direct fracture <br /> connection to the mine workings must occur and remain open. To <br /> date, this has not occurred in Lone Pine Gulch in the F Seam under <br /> cover as low as 120 feet. <br /> The water balance will not be significantly affected even if the <br /> maximum estimated inflows occur, since any mine inflows will <br /> ultimately be discharged back to the North Fork of the Gunnison. <br /> i. Refuse Material Disposal Impacts on Ground Water - <br /> Lower Refuse Disposal Area - Refuse is generated through the <br /> mining process and will be disposed of on the Lower Refuse <br /> Disposal site. The lower refuse pile is permitted for <br /> permanent disposal of 1.09 million cubic yards of mine <br /> development waste, and sediment pond cleanout material. <br /> To date the lower refuse pile has not impacted the ground <br /> water zone near Sylvester Gulch. Because of the low <br /> permeability of the colluvial soils and the lack of a ground <br /> water table near the surface in the colluvium, no impacts on <br /> ground water are anticipated. Water monitoring well SG-1, <br /> located near the site of the soil stockpiles, other water quality <br /> monitoring stations on Sylvester Gulch, and sites above and <br /> below the mine on the North Fork of the Gunnison, provide <br /> 32 <br />