Laserfiche WebLink
Dan Hernandez <br />June 3, 2013 <br />Page 5 <br />areas spread through the central area and into the southern portion of the coal field in the early <br />1900's. Over 177 abandoned mines with 600 acres of existing associated surface disturbances <br />have been identified by the Mined Land Reclamation Division's Inactive Mine Program. <br />Hvdrotteolou of the Southfield Mine Site <br />The geology and the occurrence and movement of groundwater within the area of study are <br />complex. The Southfield Mine Water Riphts Engineering Report prepared by Bishop, Brogden, <br />& Rumph, Inc. in February 1987 provides good background information and a good overall <br />description of the physical setting and stratigraphy of the site. This information is summarized <br />here along with excerpts from the DRMS permit document for the Southfield Mine and recent <br />Permit Findings documents because it is critical to understanding the hydrogeology of the site. <br />Geology <br />The Southfield Mine permit and lease boundaries are located northeast of the Wet Mountain <br />fault, straddling the axis of the Chandler syncline. The syncline generally plunges northwesterly <br />in this area; its southwestern limb is steeply inclined near the Wet Mountain fault, but its <br />northeastern limb is much less inclined. Since the land surface slopes to the northeast, the <br />subcrops or outcrops of the geologic units comprising the syncline are higher in elevation on the <br />southwestern rim than on the northeastern rim. Geologic units important to the hydrogeology of <br />the area are the Pierre Shale, Trinidad Sandstone, and the Vermejo and Raton Formations. The <br />mine property lies in the Newlin Creek drainage, a tributary of Hardscrabble Creek, which in <br />turn is tributary to the Arkansas River. A generalized stratigraphic column is provided in <br />Appendix B. <br />The Pierre Shale outcrops approximately 1.5 miles east of the mine area. The shale unit consists <br />of 3,900 feet of olive -gray clay and silt layers that contain bentonite and marine fossils. It is a <br />non - coal - bearing unit that exhibits very low hydraulic conductivity and thus is considered to be a <br />relatively impermeable unit. At the top of the Pierre is a sequence of thin, inter - bedded <br />sandstones and mudstones. <br />The Trinidad Sandstone, directly above the Pierre Shale, outcrops about 1.0 mile east of the mine <br />site and is composed of massive buff to yellow sandstones ranging from 40 to 90 feet in <br />thickness. The Trinidad Sandstone is indicative of a prodeltaic depositional environment. <br />The primary coal bearing formation in the synclinal basin is the Vermejo, which is <br />approximately 925 feet thick near the center of the permit area. The Vennejo Formation overlies <br />the Trinidad Sandstone and is the coal- bearing unit of mining interest to the Southfield operation. <br />The Vermejo Formation consists of a complex network of mudstones, siltstones, sandstones and <br />eleven coal seams, all indicative of a vast fluvial delta and plain sequence. The coal units that <br />were mined by EFCI were the Red Arrow and Dirty Jack O'Lantern, which lie approximately <br />325 feet above the top of the Trinidad Sandstone. The Red Arrow seam ranges in thickness from <br />4 to 7 feet and is a moderate to high sulfur coal with 3 recognizable units separated by bony <br />layers of ash. The Jack O'Lantern seam is a low sulfur coal that ranges in thickness from 4 to 8 <br />feet and also consists of 3 recognizable units separated by boney ash layers. The interbedded <br />