2012-03-07_HYDROLOGY - C1981033 - Laserfiche WebLink

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Sandra Brown March 7, 2012 Page 4 occurrence of the landslide. This spring is located near the toe of the hill slope, approximately 20 feet east and 20 feet up slope from the eastern terminus of the slide mass. Initially the spring was estimated to yield approximately 20 gpm at approximately 85 °. The spring also exhibited a distinct reddish -brown color. This spring was postulated by WWE to issue from the backfilled portal of the abandoned Edwards B -Seam coal mine. The warm spring lies almost directly down slope from, and in line with, the eastern terminus of the landslide. The spring may be in hydraulic connection with the basal failure plane of the slide. Several remnant concrete structures suggest the backfilled Edwards mine portal may exist twenty feet east of the spring. The Division's experts determined that water was the triggering mechanism, causing failure by saturating the colluvial materials at or near bedrock in the upper part of the slide. The Division concluded that the November, 1997 landslide was initiated by groundwaters emanating from the bedrock beneath the failed colluvium. Observations of the slope geomorphology, stratigraphy of colluvial deposits, and pedologic development suggested that the initiating groundwater discharge was a new phenomena or changed condition, which had not been occurring for any significant length of time. These observations led the Division to conclude that some recent changed condition in the local groundwater regime caused ground water to begin discharging beneath the steep colluvial slope, causing the landslide. On November 20, 1997 the Division inspected the slide area and measured the flow of the spring emanating from the east side of the slide scarp at 10 gpm with a temperature of 80.6° F. On November 26, 1997 the Division issued Notice of Violation No. CV -97 -022 to the West Elk Mine for the transfer and storage of underground mine water to the Northwest Panels Sealed Sump, resulting in discharge of mine water to adjacent lands creating adverse hydrologic impacts and landslide activity occurring at the Bear No. 3 Mine facilities area. The important result of this was remedial action by the West Elk Mine to complete removal of all waters stored in the Northwest Panels Sealed Sump in a legal manner in compliance with all applicable laws and regulations. This was done by installing the Lone Pine Gulch pipeline previously described above. It is important to note here that this was done in cooperation with the CDPHE. The water was discharged to Lone Pine Gulch and ultimately to the North Fork of the Gunnison River without any treatment needed other than energy dissipation and erosion control. The occurrence of the spring and the landslide were extensively studied as a result of the issuance of the NOV. In the PHC section of MCC's permit document it is stated that "if water stored in the NW Panels sealed sump made its way to the B Seam outcrop downgradient from Somerset, it would be discharged into the North Fork as springs and seeps along the B Seam outcrop ". However, to this day MCC still contests that any water from the NW sealed sump entered the Bear Mine. Finally in August of 1998, the Division vacated the Notice of Violation for the following reasons. Based on all of the technical information submitted by Mountain Coal Company and gathered by the Division, it appeared that MCC provided acceptable evidence that the West Elk Mine is not the sole source of water discharging from the Edwards Portal location. MCC also provided evidence that the water discharging from the Edwards Portal did not cause the landslide located above the Bear Mine yard. The history and discussion of the Lone Pine Gulch pipeline is relevant because it served the important purpose of conveying the sumped mine inflow water off of the hillside and relieving