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Most of the coal produced at the mine came from the 001 North <br />• Section of the mine. This section is bounded on both sides by <br />normal faults which form a graben. As was expected, roof control <br />problems increased as the mine progressed further to the Northeast <br />under increasing overburden. This section of thre rtrine was <br />abandoned in late April of 1990 and sealed at crosscut 3l in <br />August 1990. <br />Another section (002 NortFr) is currently being driven parallel to <br />001 North Section from the East Mains. It is anticipated that the <br />002 North Section will advance approximately 3,000 feet to the <br />north. Also being driven as time allows is the proposed rock <br />slope to the upthrown block of coal east of the existing rnine <br />workings. <br />Water Inflow L Discharge <br />Previous hydrologic reports have given evidence that the inflow of <br />water to the mine can be attributed to dewatering of a perched <br />aquifer as well as surface water infiltration along the faults of <br />the graben. During idle years a clear picture of mine water- <br />inflows was obtained because water that. collected in the faces was <br />regularly pumped to NPDES point 002 and discharged. The quantity <br />of water discharged was recorded on a meter and a correlation with <br />precipitation was made. The steady decrease in the amount of <br />water pumped from the mine during the idle years is evidence of <br />the creation of a dewatered zone in the saturated coal strata. <br />• The decrease is also evidence that there i-, little communication <br />with the comparatively large aquifer- within the East Salt Creek <br />alluvium across the west fault of the graben. <br />With the resumption of mining. water was not disci~arged from the <br />mine: rather. water was used during the mining cycle or stored in <br />sumps underground in anticipation of future needs. No water has <br />been discharged from the mine to Point 002 since April of 1987. <br />Since water was not being discharged regularly. correlation of <br />discharges with precipitation and monthly inflow for the year was <br />not possible. The majority of the water that infiltrated the mine <br />was used for dust suppression in the mining cycle. Therefore. <br />mine dewatering became a function of the amount of coal produced. <br />Monthly water use records are shown in Table 1. Historic water <br />use or discharge is shown in Table 2. <br />When ruining resumed, additional area in the saturated portion of <br />the graben was opened increasing the flow of water into the mine. <br />The inflow of water went. from a low of D.80 gpm in 1988 to a high <br />of 3.87 gpm in 1990. Water flowing downdip into the faces of <br />Section 001 NortFr was pumped to the water sump at Crosscut 29. <br />The water was then used as needed. On April 27. 1990 Section 001 <br />was abandoned: the water flowing into this area of the mine became <br />inaccessible. From May through the end of June. the water stored <br />in the sump was used. Water for mining and roadway dust <br />• suppression was trucked to the rnine the rest of 1990. Potable <br />water has also been imported to the site for use at the bathhouse. <br />Page - 2 10/l9/90 <br />