Laserfiche WebLink
DESCRIPTION OF THE ENVIRONMENT <br />Geology <br />The Marr Mine is located in North Park, an intermountain valley bound to the north by <br />Independence Mountain, to the east by the Medicine Bow Range, to the south by the Rabbit Ears <br />Range, to the southeast by the Never Summer Range, and to the west by the Park Range. There <br />is a complex structure of folding within the North Park Basin, known as the North Park Syncline. <br />Within this syncline, there are numerous smaller folds generally trending southeast in the permit <br />area. The permit area occupies the western, steeper flank of the asymmetrical Johnny Moore <br />syncline, which plunges to the south. The McCallum anticline is located just to the west, and <br />parallels the permit area. The dip of the coal within the permit area ranges from 45 to 86 degrees <br />to the east and northeast, averaging 68 degrees. Two faults intersect the permit area along Bush <br />and Williams Draws. These strike from southwest to northeast and have a displacement of 100 <br />to 150 feet. <br />The Marr Mine produced coal from the Sudduth seam, a seam ranging from 35 to 75 feet in <br />thickness, averaging 50 feet. This seam is the lowest coal found in the 5000-foot-thick Tertiary <br />Coalmont Formation. Shale overlies the Sudduth seam, while a 50-foot-thick, fine-to-medium <br />grained sandstone lies between the coal and the underlying Pierre Shale. Quaternary alluvium of <br />sand, gravel, clay, dune sand, and glacial till is found along the creeks and rivers in the area. <br />Geochemical Analysis of Overburden and Underburden <br />Kerr Coal Company drilled numerous holes within the permit area and conducted toxicity <br />analysis of the overburden and underburden. A total of 67 samples were taken from 18 drill <br />holes. Dissimilar lithologies were sampled at five-foot intervals and analyzed for potential <br />toxicity. The areal sampling density was a minimum of one hole every 1,300 feet. Other drill <br />hole sample analyses were available from the USGS and the BLM for areas in and around the <br />permit area. Kerr Coal Company sampled and interpreted the results using the published <br />guidelines of the Wyoming Department of Environmental Quality and the Montana Department <br />of State Lands, Reclamation Division. <br />Interpretation of the analysis indicated no overall overburden or underburden toxicities. Some of <br />the analyses showed a few values that exceeded the suspect levels identified in the guidelines <br />from one or the other of the two States. Levels for nickel were marginally in the suspect range <br />(Wyoming guidelines). The overburden was found to be alkaline, however, and nickel in the <br />concentration ranges found at the mine would, according to certain studies, not suggest plant or <br />hydrologic toxicity problems. <br />Some sample analyses showed marginal potential toxicities for selenium. Of 54 samples taken, <br />12 exceeded the suspect level (Wyoming guidelines). Of these 12 samples, eight came from <br />holes drilled with mud. This was believed to suggest that some contamination had occurred. <br />The remainder of the samples that showed elevated levels represents 12.7 percent of the <br />8