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• Lan¢::o Cmn'w: f/n;r - Grorn;~irct<r ; rd:n:.'c! Rr~or. Therefore: vs = Ki/rte vs = 1.22 x 10' ft/day (0.0078 ft/fr)/10 h vs = 9.52 x 10'' ft/day or 3.47 ft/yr (for si[e-specific) v, = 0.0408 fr/day (0.0078 ft/ft)/ 10 9~ v, = 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 [he surrounding Ra[on formation. The transmissiviry of this zone indicates that water production for domestic use ranges from infeasible to poor. Underburden The underburden in the Lorencito Canyon Permit area has a total estimated thickness of up to 1000 fee[. Recharge to the underburden is via inflow from fractures or overlying units. Infiltration ra[es for [his unit are anticipared as low. Discharse from this unit is anticipated as beine low. Groundwater in the underburden is charac[erized as beine under confined condi[ions. 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 drilline through alluvium (MW11 and MW-~) and at ]00 feet in the boring for site MW-6. No appreciable increase in flow was noted during the drilling of [he underburden zone. All underburden Primero wells were set in the sandstone immedia[ely below the Primero coal seam. The potentiometric surface of the underburden was determined from data from wells MW-4, NIW- 5, and MW-6. The flow direction established by this data is to the northeast. The gradient is 0.0084 ft/ft or 44.60 ft/mi. This data compares very favorably to the regional gradient established by Howard in the 1982 study. A copy of this map is included as Nlap ?.04.7-6. Aquifer characteristics of the underburden were determined via slug tes[ing. A slug test was performed in well MW-4U, and recovery of the well was moni[ored for approximately 7 hours. Within this time period no recovery was noted. This indicates an extremely low hydraulic conductivity for the underburden. Estimated hydraulic conductivity would be on the order of 10 ` ft/day. Storativity would be estimated as 1Q' to 10"6. A second well IvIW-6U was also tested. This well has a sound of either cascading water or gas. According to the slue test results of this well, [his ma[erial would have a hydraulic conductivity 5 [0 7 orders of magnitude higher [han any of the other consolidated rock wells onsite. This da[a indicates either the in[erception of fracture zone, or the releasing of gas [hrough the well. This data would not be considered as representative of the underburden zone. Gmm~du aicr l]j~Deccm6rr 9. I°ori 44 (revised 6/30!97)