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<br />1 <br />t <br /> <br />1 <br /> <br />n <br />J <br /> <br />L~ <br />r <br /> <br />LI <br /> <br />WATER INFLOW INTO THE <br />ORCHARD VALLEY COAL MINE <br />PAONIA, COLORADO <br />1.0 INTRODUCTION <br />Colorado Westmoreland, Inc. (CWI) has been requested by the <br />Colorado Mined Land Reclamation Division (MLRD) to submit a study <br />of water inflow into the Orchard Valley coal mine. <br />This study should address the existing inflow and the <br />projected inflow anticipated with the expansion of the mine under <br />the current mining permit application. <br />The main concern is the potential for material damage to the <br />owners of water rights caused by mining. In this report inflow <br />into the mine caused by natural seepage and it's consequences are <br />addressed. The potential for material damage due to subsidence <br />was addressed in Volume 3, Subsidence in the Application for <br />permit to mine. Particular attention is given to the sections of <br />the mine where mining under Stevens Gulch and East Roatcap Creek <br />would occur. <br />This report presents the study of probable future water <br />inflow into the Orchard Valley mine, the potential for impacts on <br />water users within the area, recommendations for mine water <br />monitoring and the time necessary to flood the mine after <br />abandonment. <br />Data presented in this report are based on documentation <br />submitted to the MLRD in the form of the application for <br />underground coal mining and reclamation permit. <br />2.0 GROUND WATER INFLOW INTO THE MINE <br />2.1 Existing Mine <br /> <br />~' <br /> <br />1 <br />The Orchard Valley mine can be considered a mine with very <br />low water inflow. Actual water inflow into the entire mine at <br />the end of year 1984 was only about 4 gallons per minute. The <br />presented value of the total mine inflow of 4 gpm should be <br />considered conservative because the average inflow throughout <br />1984 was lower. The relation between the total quantity of water <br />inflow into a mine and the total quantity of coal mined out is <br />called the coefficient of water abundance. This coefficient <br />expresses the degree of water problems related to mining. The <br />coefficient of water abundance for the Orchard Valley mine is <br />unusually low for an underground coal mine, amounting to only <br />0.009 tons of water inflow per one ton of mined coal in 1984. <br />1 uiuiau.r.r:ucrosrcrwr, <br />