Laserfiche WebLink
0 TETRA TECH <br />Wolf Creek Reserve Groundwater Investigation Work Plan <br />March 6, 2014 (revised August 6, 2014) <br />Twentymile Coal, LLC (TC) proposes to mine the Wolf Creek Coal Seam (the Wolf Creek Reserve) <br />within the area encompassed by the existing Foidel Creek Mine (Figure 1). This document presents a <br />work plan for investigating groundwater conditions related to the proposed mining of the Wolf Creek <br />Reserve. <br />SITE LOCATION AND BACKGROUND <br />The TC Foidel Creek Mine site is located approximately 20 miles southwest of Steamboat Springs, <br />Colorado, at the south end of Twentymile Park (see Figure 1). The mine operates under Division of <br />Reclamation, Mining and Safety (DRMS) permit C- 1982 -056. Surface coal mining has been conducted <br />in the area since the 1960s. The Foidel Creek Mine was established as an underground operation in <br />1983, with conversion later to the longwall method to remove coal from the Wadge Coal seam. <br />The Foidel Creek Mine is an active underground coal mining operation, having affected a cumulative <br />total of roughly 15,180 acres in south Routt County through 2012. The total Life -Of -Mine permit area <br />encompasses approximately 22,530 acres. Surface facilities and portals cover about 800 acres and are <br />located above the south - central part of the underground operations, adjacent to the reclaimed former <br />Colorado Yampa Coal Company (CYCC) surface mine spoils. <br />HYDROGEOLOGIC SETTING <br />The Foidel Creek Mine is located within the Twentymile Park Basin, a synclinal structure with a <br />northeast - trending axis. The area is drained by Foidel Creek and Fish Creek, which flow eastward and <br />northeastward through Twentymile Park into Trout Creek, a tributary of the Yampa River. Land surface <br />elevations within the mine permit area range from about 7400 feet above mean sea level (ft amsl) on <br />the northwest side of the area to about 6600 ft amsl where Fish Creek leaves the northeast corner of <br />the Permit Area. <br />Mining is currently focused on the Wadge Seam, which lies within a sequence of sedimentary rocks <br />characterized by shales, claystones, mudstones, siltstones, sandstones, and minor coal stringers <br />referred to as the Wadge Overburden. The Wolf Creek Reserve underlies the Wadge Seam (Figure 2). <br />In the proposed mine area, the Wolf Creek Seam is present at depths ranging from approximately <br />1,000 to 1,700 feet below the land surface. Approximately 150 feet of shale, claystone, siltstone and <br />lenticular sandstone known as the Interburden unit separates the Wadge and Wolf Creek seams. <br />Within the Twentymile Park Basin, groundwater is known to be present in the Wadge Seam, Wadge <br />overburden, surficial alluvium along the major creek drainages, Twentymile Sandstone about 700 feet <br />above the Wadge Seam, Fish Creek Sandstone about 900 feet above the Wadge Seam, and Trout <br />Creek Sandstone about 400 feet below the Wadge Seam. The Twentymile Sandstone and Trout Creek <br />Sandstone are regional aquifers separated from the Wadge and Wolf Creek seams by low- permeability <br />shale and interbedded shale /siltstone units. The Fish Creek Sandstone lies about 125 feet above the <br />Twentymile Sandstone and is a discontinuous, minor water - bearing unit in the area. The Wadge <br />overburden, as mentioned above, consists primarily of fine - grained, low- permeability rocks extending <br />Tetra Tech <br />3801 Automation Way, Suite 100, Fort Collins, CO 80525 <br />Tel 970.223.9600 Fax 970.223.7171 www.tetratech.com <br />