2010-02-05_REVISION - C1996083 (8)

Home Browse Search

0 2.05.6 The flooded mine workings could also affect the ground water quality and quantity in the overlying Upper and Lower Perched Water Zones. However, as stated above, the Mesaverde Formation transmits little water. Therefore, the impact the flooded mine workings will have on the quantity and quality of the surrounding strata should be minor. The Rollins sandstone, as monitored in DH-34B, NM4X98-29 and P-TC-03-01(R) has pH in the range of 7.5 to 9.6, conductivity in the 1,200 to 7,900 umhos/cm range and total recoverable iron in the 0.2 to 62.0 mg/I range. The Rollins sandstone is a confined aquifer under piezometric head. The confining shale layers above the sandstone and piezometric head should prevent any integration of water from either the D-Seam or B-Seam into the Rollins sandstone. There are two drill holes G-15 located near the mouth of Dove Gulch and DH 98-57 located in the central portion of the mine workings that provide documentation of the hydraulic isolation of the Rollins sandstone from the B-1 Seam, the lowest coal seam to be mined. In G-15 and DH 98-57 there are 77.0 and 85.1 feet respectively of identified shale, sandstone and coal between the B-1 Seam to near the top of the Rollins Sandstone. In the western mine plan area, drill holeTC-03-03 documents the isolation between the Rollins sandstone and the B-2 Seam, the lowest coal seam to be mined. In TC-03-03 there . are 23 feet of mudstone, 28.3 of sandy mudstone, 4.0 feet of sandstone and 19.2 feet of coal between the Rollins sandstone and the B-2 Seam. Map 08 provides drill logs of the three drill holes that demonstrates the hydraulic isolation of the Rollins Sandstone. The perched water below the D-Seam and above the B-Seam is or was monitored by drill holes D-58a and DH-67-D-Blw. The quality of water in this perched water being zone, as reported in the 2007 AHR show pH in the range of 7.8 to 11.6, conductivity ranges from 485 to 5030 umhos/cm and total recoverable iron ranges from 0.03 to 31.4 mg/I. Based on the quality of the mine water discussed above, mine water seepage into the perched water below the D-Seam and above the B-Seam would improve the water quality in the perched water bearing zones. The perched water above the D-Seam is or was monitored by drill holes D-58, 66 and DH-67-D-Abv. The quality of water in this perched water being zone, as reported in the 2007 AHR show pH in the range of 6.9 to 13.5, conductivity ranges from 652 to 5500 umhos/cm and total recoverable iron ranges from 0.08 to 17.7 mg/I. Based on the quality of the mine water discussed above, mine water seepage into the perched water above the D-Seam would improve the water quality in the upper perched water bearing zone. • TR-65 2.05 - 75ii 02/10