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The Vermejo Formation overlies the Trinidad Sandstone and is the coal-bearing unit of <br />mining interest to the Southfield operation. The Vermejo Formation consists of a complex <br />network of mudstones, siltstones, sandstones and eleven coal seams, all indicative of a vast <br />fluvial delta and plain sequence. The coals developed in the backwater swamp areas of the <br />river delta. The coal seams of economic importance in the area are Monarch, Red Arrow, <br />Jack O'Lantern, Vento, Manley and Rex Carbon. Total thickness for the Vermejo sequence <br />is approximately 925 feet. <br />The coal seams mined at the Southfield Mine are two of the six principal seams present in <br />the Vermejo Formation -the Red Arrow and the Jack O'Lantern. The Red Arrow seam <br />ranges in thickness from 4 to 7 feet and is a moderate to high sulfur coal with 3 recognizable <br />units separated by bony layers of ash. The Jack O'Lantern seam is a low sulfur coal that <br />ranges in thickness from 4 to 8 feet and also consists of 3 recognizable units separated by <br />boney ash layers. The permittee has provided a complete coal, roof and floor analysis in the <br />permit. For further information refer to Section 2.04.6 of the permit. <br />Ascending upward on the stratigraphic column from the Vermejo Formation is the Raton <br />Formation, a unit consisting of two members- a basal sandstone and muddy-sandy layer. <br />The Raton averages 650 feet in thickness. The erosional base of this unit marks the top of <br />the Vermejo Formation in the Southfield mine area. There are no coal-bearing units found in <br />the Raton, since its character indicates that a period of increased uplift and subsequent <br />erosion in the area followed that of the depositional low-energy environment found in the <br />Vermejo. <br />Uncomfortably overlying the Raton Formation are the sediments of the Poison Canyon <br />Formation. Similar in composition and character to the Raton, the Poison Canyon Formation <br />is coal barren and is 200 feet in thickness of alternating beds of mudstone and sandstone. <br />Covering most of the topographic ridges in the Southfield mine area are a series of <br />Pleistocene boulder/colluvial/alluvial deposits. Most of the boulders consist of gneiss, schist <br />and sandstones derived from erosion and mass wasting of the Wet Mountain uplift to the <br />south and west. Depositional thicknesses range from 5 to 100 feet in places near the mine <br />site, with 20 feet recorded in the loadout area of the mine. <br />Hydrology <br />An extensive review of both the ground water and surface water hydrology can be found in <br />Section 2.04.7, 2.05.6 and 4.05 of the permit application. Below is a brief summary of the <br />ground and surface water issues at the Southfield Mine. <br />Ground Water <br />Due to the extensive underground mining activities in the area, ground water baseline <br />information was difficult to obtain. Trends for ground water were established and have been <br />recorded since the mine opened as the Dorchester No.2 in the 1970's. Ground water flow is <br />difficult to predict based on the tendency for the ground water to flood old workings in the <br />area. Many residential welts have been drilled into the old abandoned workings and provide <br />residents with water. In the mine area, evaluation of groundwater resources is based <br />