REP50650 - Laserfiche WebLink

Home Browse Search

r The amount of water entering the mine as ventilation intake air humidity is based on monthly mean temperatures from Figure II.C-2 on page II.C-9 of the Mining Permit and the yearly mean relative humidity of 56% found on page II.E-1 of the Mining Permit. The absolute humidity, the actual amount of water in the air, is calculated from these data and an average ventilation quantity of 450,000 cubic feet per minute The amount of water entering the mine from the surrounding strata is partially estimated by ' identifying all known seep areas and estimating the flow rate from each. During January 1994, a survey of the accessible areas of the mine workings was conducted to identify the location and flow rates of all seeps. The locations and flow rates of the seeps are shown on Plate 1. Due to the very low flow rates measured, the flow rates are shown in gallons per day. Most, if not all, of this water leaves the mine in the form of humidity in the ventilation air flow. There are very few locations in the mine that produce water over the long term. Most wet areas encountered during mining flow for relatively short periods (hours or days), in the form of profuse drips, and then gradually dry out as the flow stops and the ventilation air carries the moisture out of the mine. These areas are generally associated with stackrock in the roof. stackrock is a sandstone laminated with very thin layers of silty carbonaceous ' material. These laminations range in thickness from a few inches to a few millimeters thick. Water in the stackrock appears to be connate in origin and not from the rechargeable groundwater systems. Virtually all of the geologic water enters the mine from the surounding strata from broken rock in the gob behind the longwall face. BME believes there was insignificant amount of seepage during the 1997-1998 water year. The smallest quantity of water entering the mine is the incidental category. This category includes leakage from water lines, dust control watering in the haulage entries, and washdown water used in the slope and other locations. It has been assumed that 10% of the water used for production equipment will be used under this category. ' Outnoinst Water As coal is mined, it is wet by dust control sprays on the continuous miners, the longwall shearer and at transfer points along the conveyor belt system. This water is then carried out of the mine as surface moisture on the raw coal. This added coal surface moisture represents a 2% increase in the raw coal moisture content. The raw coal tonnage A produced during this reporting period was 2,031,983 tons. Water leaving the mine as ventilation humidity represents a large quantity in the water balance. The temperature of the exhaust ventilation air is almost constant, at 60° F. ' No underground water is being pumped out since the fire episode. For the remaining life of the D-Seam mine, the underground water will be left to fill the mined out areas. 1 12