2010-11-16_PERMIT FILE - C1996083A (22)

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2.04.7 Hydrology Description • outcrop, yet the near vertical exposures and sporadic precipitation precludes any large scale infiltration. The general groundwater flow in the Mesaverde perched water zones is toward north, following the basin structure. An interpretation of the potentiometric surface in this water bearing strata is shown on Maps 10, 10A, 10B and 11. This interpretation indicates that the recharge area into the perched water zones is near the outcrop of the sandstone and coal seam subcropping underneath the local drainages. Drill holes 13, 15, 16, 25, 34B, 38, 39, 42, 49, 52, 54, 55, 57, 57a, 58, 58a, 65, 66, DH -67B, DH -67D, DH- 67Abv, DH- 67BIw, DD- NM4X98 -27, DD- NM4X98-28, DD- NM4X98 -29, TC- 03- 01(B), TC- 03- 01(R), TC- 03 -02, TC -03- 03 were completed as monitoring wells in the bedrock following exploration. Refer to section 2.05.6 for further discussion of the deep bedrock groundwater monitoring program. Lower Perched Water Zone and Rollins Sandstone A sufficient number of data points were obtained from the drill holes to plot potentiometric surfaces. As seen on Maps 10A, 10B 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. East of Terror Creek 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 northeastern 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 lower perched water bearing zone contours were not projected into the west mining area since the geohydrologic setting changes west of Terror Creek and most of the projected contours would be located north of the western mining area. Map 10A presents the regional projection of the potentiometric surface above the B -Seam. 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 M 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 PR -12 2.04-36- 06/10 �9 PPRaVCD 11//6110