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• Ruft 2: P~rmitt <br />The seepage velocity of the water through the coal cannot be calculated without a gradient. <br />Gradient in this zone is unknown; however, the potential pumping rates from wells in the coal can <br />be calculated. Utilizing the formula Q=Ts/2000 this calculation can be performed; where the <br />constant 2000 is used for confined zones. Therefore: <br />Q = 51.23 g/d/ft [50 ft (for available drawdown)]/2000 <br />Q = 1.28 gpm <br />This would compare favorably to the experience of field personnel with bailing this well; <br />therefore, the values derived during testing would appear valid for this water-bearing unit. <br />Considering the transmissiviry of this zone, the potential for domestic water supply is considered <br />poor. <br />Interf~urden <br />The interburden in the Lorencito Canyon Permit area has a total estimated thickness of <br />approximately 570 feet. Recharge to the interburden is via precipitation on outcrop surfaces, and <br />from inflow from fractures or overlying units. Infiltration rates for this unit are anticipated as <br />low. Discharge from this unit is anticipated as being low. <br />• Groundwater in the interburden is characterized as being under confined conditions. Water was <br />not apparent in two of the Ciruela borings into the interburden; however, the third well (MW-lI) <br />had water present. Wells MW-2I and MW-3I both have been dry during the baseline period. <br />These wells were set in the sandstone directly below the Ciruela. Water was present in all three <br />wells installed in the interburden above the Primero. Water was encountered in the borings for <br />these wells; however, this water was encountered during the drilling through alluvium (MW1l and <br />MW-5) and at 100 feet in the boring for site MW-6. All interburden Primero wells were set in the <br />sandstone immediately above the Primero coal seam. <br />The potentiometric surface of the interburden is to the east-southeast, based on the data from the <br />wells MW-4, MW-5, and MW-6 (Map 2.04.7-4). The gradient of this surface is 0.0055 ft/ft or <br />29 ft/mi. This is a relatively shallow gradient. Comparison of this gradient to the regional <br />gradient of Howard (1982) shows that this gradient is much more easterly. The gradient accepted <br />as the regional gradient is generally to the north or northeast in the permit area. <br />Characteristics of the interburden were determined via slug testing. A slug test was performed <br />in well MW-6I, and recovery of the well was monitored for approximately 17 hours. Within this <br />time period the water level recovery was extremely limited. Extrapolation of the slug test curve <br />data indicates complete recovery would take approximately 695 days. This indicates an extremely <br />low hydraulic conductivity for the interburden. Estimated hydraulic conductivity as determined <br />via this testing was 1.28 x 10; ft/day. This value can be translated to transmissiviry (T) by the <br />r1 <br />LJ <br />PERMIT.d]6\DUemhr 10. 1996 2.04-1 S <br />