2009-01-14_PERMIT FILE - C1996083A (2)

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2.04.7 Hydrology Description • Lower Perched Water Zone and Rollins Sandstone A sufficient number of data points were obtained from the drill holes to plot portions of the potentiometric surfaces on the maps. As seen on Maps 10 and 11, the potentiometric contours generally fit the geohydrological setting of the permit area in that the saturated horizons (or potentiometric surface) gently dip northward, following the structural attitude of the bedrock horizons. The lower perched water bearing zone is more continuous than the upper perched water bearing zone. Map 11 projects the piezometric surface of the lower perched water bearing zone in the northern portion of the permit area. Map 11-1 is a fence diagram showing the lower perched water bearing zone in relation to monitoring wells and the underling B-Seam. The upper perched water bearing zone is discontinuous. It is not possible to predict a peizometric surface over an extensive area for the upper perched water bearing zone because of the variability of the water levels in the monitoring wells and the areas where data indicates the upper perched water bearing zone is dry. The Rollins Sandstone in the permit and adjacent area is characterized as dry along the outcrop and develops piezometric head as the formation dips to the north. Monitoring well DH-34B, NM4-98-29 and TC-03-01(R) are completed in the Rollins Sandstone. The water level in all three wells is under artesian conditions ranging from 200 to 475 feet. Monitoring well NM4-98-29 was located underground in the Bowie No. 2 Mine, D-Seam north mains. Oxbow has two • wells completed in the Rollins Sandstone (SC-1 & SC-2) and they are also reported to be under artesian conditions (SMC permit section 2.04.7). Mountain Coal Company has one well completed in the Rollins Sandstone (SOM-128-H) which is also under artesian conditions (MCC 1994 AHR). The quality of the water in the Rollins Sandstone is poor with the Bowie No. 2 Mine wells exhibiting better quality than adjacent mines. The following table presents typical values for selected chemical parameters from the water in the Rollins Sandstone from the three mines referenced above: ROLLINS SANDSTONE WATER QUALITY Alkalinity Chloride Sodium TDS BRL #2 DH-34B 3430 625 1940 4660 BRL #2 NM4X98-29 3420 540 1560 3670 BRL #2TC-03-01 (R) 1996 460 1030 3250 Oxbow - SC-1 2580 3140 3120 7400 Oxbow - SC-2 3540 3150 3450 8500 MCC SOM-128-H 3940 2610 3060 8230 Reference: SOM 1992 AHR, MCC 1994 AHR In general, groundwater within the Mesaverde Formation is of sodium bicarbonate type, and the total dissolved solids ranges from 900 to 8,960 ppm. • High mineralization and high sulfate and sodium content of this groundwater precludes the use for potable, stock and irrigation purposes. PR-10 2.04 - 28 - 10/08 A PPRov~cU i-Izy~aB