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Lorencila Cam~on Mine ~ Groundwater Techrtira( Renart <br />• Examination of a flow net of the system (Figure GW-8), indicates that some of the recharge is <br />discharged at the outcrop surface area via evapotranspiration. In addition, springs would generally <br />be anticipated to emanate for the coal at the outcrop. Spring and seep surveys conducted during <br />the baseline period did not determine springs to exist at this particular outcrop area. This may be <br />the result of small amounts of recharge combined with the high evapotranspiration in the area. <br />Groundwater in the Ciruela is characterized as being under confined conditions. Water was not <br />apparent in any of the borings into the overburden; however, wells were set into the Ciruela. Well <br />MW-2 has been dry and no well was set in the Ciruela at the location for MW-3 due to dry <br />conditions. Water was present in only one well installed in the overburden (MW-1C). <br />Groundwater in the Ciruela appears to be intermittent throughout the zone; therefore the <br />potentiometric surface could not be determined. <br />The characteristics of the Cituela water-bearing zone were determined via slug testing. A slug test <br />was performed in well MW-1C, and recovery of the well to static water level required <br />approximately 16 hours of data collection. This indicates low hydraulic conductivity for the <br />Ciruela. Estimated hydraulic conductivity as determined via this testing was 1.37 ft/day. <br />Storativity estimated by this method (Cooper, Pappadapoulous) was 2.14 x 1Q6. The hydraulic <br />conductivity determined was also within the same order of magnitude as the value determined by <br />Howard (1982) for the Raton Formation coals. Utilizing the hydraulic conductivity, and a coal <br />• thickness of 5 feet (MW-4C well, saturated thickness), the transmissivity can be derived as: <br />T=Kb <br />T = (1.37 ft/day) (5 ft) <br />T = 6.85 ftZ/day or 51.23 g/d/ft <br />This value is within the range characteristic of a coal unit and compares favorably to the values <br />in the study by Howard (1982). <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 />• <br />GrounEwamr.i75\December 9. 1996 39 <br />