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George Patterson <br />September 19, 2013 <br />Page 4 <br />The actual degree of connection between the 3 North area and the West Mains is unclear. Our <br />conversations indicate that there is potential connection between the 3 North area and the West <br />Mains in the area of 3 North where both the Red Arrow and Dirty Jack O' Lantern coal seems have <br />been mined. It is my understanding that due to the mining of both coal seams and the pillaring in <br />that area, the mine has collapsed and consists of rubble at that location. The floor elevation in the 3 <br />North area at that location is approximately 5,766 feet and the floor elevation in the West Mains in <br />that area is approximately 5,810 feet. Accordingly, if connection exists at this location, the 3 North <br />and West Mains areas will fill together before reaching the bottom of the MW -NW well casing at an <br />elevation of 5,860.5 feet. If this is the case, then the mine will fill as a single unit and it will take <br />approximately 120 years for the water in the mine to reach the bottom of the MW -NW well casing. <br />If this potential connection does not exist, then the 3 North area will fill separately from the rest of <br />the mine and it will take approximately 106 years for the water in the mine to reach the bottom of <br />the MW -NW well casing. The purpose of Conceptual Model Nos. 1 and 3 in our July evaluation <br />letter is to address the uncertainty of this potential connection. As presented, depending on the <br />actual conditions in the mine as a whole and at the location of mine collapse in the 3 North area, it is <br />estimated that water in the mine will not reach the elevation of bottom of the MW -NW well casing <br />until between 106 and 120 years after the year 2000 or until between the years 2106 to 2120. <br />We hope that this letter provides the additional information requested by Janet Binns, but if you have <br />any questions or need additional information, please do not hesitate to contact us. <br />Very truly yours, <br />BISHOP - BROGDEN ASSOCIATES, INC. <br />a <br />Timothy A. Crawford, P.G. <br />Project Manager/Hydrogeologist <br />TAC /jeb <br />Enclosures <br />2018.04 <br />