Laserfiche WebLink
r~ <br />u <br />Ground Water Flow <br />The direction of regional ground water flow in the permit area is <br />eastward away from the center of the Raton Basin. Recharge is believed to take <br />place largely in the western uplift area where the west limb of the syncline dips <br />upward at close to 90°. The ground water flow systems within the permit area <br />generally conform to this regional scheme although historic mining and local <br />geology in the area have distorted the flow directions. The underground mines now <br />act as large storage reservoirs and provide some degree of interconnection between <br />various coal zones. Furthermore, the dikes and faults in the permit area, acting as <br />low permeability barriers, tend to align the direction of ground water flow. Thus, <br />bedrock ground water flows from the center of the Raton Basin, discharging along <br />the subcrop limits of the water-bearing strata of the Vermejo Formation. <br />Based on water inflows from drilling response tests and pump testing, <br />• the coal seams have been identified as the most permeable water-bearing strata. <br />Other significant water-bearing strata include the Lennox sandstone which overlies <br />the Lennox Coal Seam, and, at shallow depths, the Trinidad Sandstone which <br />underlies the Vermejo Formation. Table 2 is a compilation of the piezometers <br />installed in this study, their locations, depths, strata and calculated values for <br />hydraulic conductivity. Flow through sandstone units is primarily intergranular, <br />following bedding planes. Flow through the coals occurs in joints and openings <br />along bedding planes. The shale beds of the Vermejo Formation in the permit area <br />are generally discontinuous and interbedded with sandstone units having occasional <br />sandstone layers that are quite massive. These shale beds are considered to be <br />several orders of magnitude less permeable than coal or sandstone units and, hence, <br />tend to act as aquitards. <br />Although surface water flow is seldom recorded in Maitland and Gordon <br />Arroyos, subsurface flow in the alluvium has been documented. The alluvium is <br />generally unconfined and mostly unsaturated, therefore, no specific data exists on <br />• <br />-7- <br />