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Water Inflow j 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 the mechanism of mine dewatering was <br /> direct discharge to NPDES point 002 . The quantity of water <br /> 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 is 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 discharged from the <br /> mine: rather . water was used or stored in sumps underground in <br /> anticipation of increased needs. Since water was not being <br /> disenaroed regularly, correlation of discharges with precipitation <br /> and monthly inflow for the year was not possible . The ma for i tv of <br /> the water that infiltrated the mine was used for dust suppression <br /> the raining cvcle . Therefore , minx, dewatering became a function or <br /> the amount of coal produced . <br /> When mining resumed, additional area in the saturot en portion of <br /> the graben was opened increas ; ng the flow of water invo the mine . <br /> Water has also been imported to the site for use ok roads and at <br /> the batwouse. Estimates of Line amount of water used indicate <br /> that the inflow of water has increased to awproxim _elv 1 . 5 <br /> gallons per minute from the 0 . 8 gallons Per minute reported for <br /> the last period. A tabulation of water inflow/outriow from the <br /> mine is included as Table 1 . Fable 2 is a record w the flows for <br /> the period 1921 to 1989. <br /> Source of Water Influx•: <br /> As detailed in previous reports , the waver flowins into the mine <br /> seems to be a mix of water infiltrating the graben along the <br /> faults and water- which is stored in the coal sears. The zone of <br /> saturation of the coal seam was initially estimated using the <br /> results of exploration drilling. The drilling indicated That <br /> holes in the McClane graben were dry: specifically. holes 7- 15-3 <br /> and 7-21 - I . Additionally. a piezometer installed downdip from the <br /> mine outside of the graben has not realized water to date. Since <br /> the well is down-dip and is dry. Salt Creek surmises that the <br /> water flowing into the mine is from a perched aquifer in the area <br /> of the coal mine. <br /> Page - 2 2119190 <br />