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• Rule 2: Permitr determined was one order of magnitude lower than the value determined by Howard (1982) for the Raton Formation coals. Groundwater seepage velocity (vr) can be determined from the gradient (dh/dl, or I), effective porosity (tt~, and hydraulic conductivity (K). Seepage velocity represents the rate at which water actually moves through the pore spaces. The relationship vs=Ki/ne, is utilized to determine this value (Fetter, 1980). From the above analyses: K = 1.22 x 10"' ft/day (for site specific tests), 0.0408 ft/day (for regional values) I = 0.0078 ft/ft ~=10% Therefore: vs = Ki/rt< v~ = 1.22 x 10-' ft/day (0.0078 ft/ft)/10 % v, = 9.52 x 10-3 ft/day or 3.47 ft/yr (for site-specific) v, = 0.0408 ft/day (0.0078 ft/ft)/10 % yr = 3.18 x 10"' ft/day or 1.16 ft/yr (from regional data) • These velocities indicate that ground water flow through the coal is higher than the surrounding Raton formation. The transmissivity of this zone indicates that water production for domestic use ranges from infeasible to poor. Under6urden The underburden in the Lorencito Canyon Permit azea has a total estimated thickness of up to 1000 feet. Recharge to the underburden is via inflow from fractures or overlying units. Infiltration rates for this unit are anticipated as low. Discharge from this unit is anticipated as being low. Groundwater in the underburden is characterized as being under confined conditions. Water was present in all three wells installed in the underburden below the Primero. Water was encountered in the borings for these wells; however, this water was encountered during the drilling through alluvium (MW~ and MW-5) and at 100 feet in the boring for site MW-6. No appreciable increase in flow was noted during the drilling of the underburden zone. All underburden Primero wells were set in the sandstone immediately below the Primero coal seam. The potentiometric surface of the underburden was determined from data from wells MW-4, MW- 5, and MW-6. The flow direction established by this data is to the northeast. The gradient is 0.010 ft/ft or 52.7 ft/mi. This data compares very favorably to the regional gradient established by Howard in the 1982 study. PERMIT.revVuly lS, 199] 2.04-19 (ievlsed 7/23/97)