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Binns, Janet <br />From: WD & Andrea Corley Jr. [ajjc @att.net] <br />Sent: Monday, November 21, 2011 3:41 PM <br />To: Binns, Janet <br />Subject: Re: Canyon City reclamation project <br />DI S CC)-v' <br />flo cs <br />Ms. Binns, <br />None of us know what the cause of the subsidence is. George Patterson thinks it is from the previous mining. <br />Because the actual cause and effect is unknown, however, we have done considerable work to determine what <br />facts are known. I have suggested that your aerial photos might show when the caving happened. At least one <br />of the holes is large enough to maybe appear on the photos. Southfield did mine out this area with pillaring <br />shown on their map. There were no subsidence monitoring points in this exact area, but there was subsidence <br />of other nearby areas. For example, there was subsidence between 1996 and 2000 of monitoring points called <br />CV and Axle which are north and east of the current subsidence holes, and there was subsidence across about <br />400 feet of the County Road 15 also north of this area. We have also found an open drill hole to the north <br />which is shown on the Southfield map to intersect the 2 North Mains. The water level is at about 87 ft.; the <br />Southfield works were at about 460 ft. George has furnished us with the Newlin Creek water flow studies as <br />reported to your Division. This hole is SF87 -07 which is west of the NWMW monitor hole. It is inby and <br />down dip. <br />The rest of this is based on observations and possibilities. We think that the area of the current subsidence holes <br />also was subject to wide area general subsidence which may have made the mine cover unstable. We think the <br />present holes are less than a year old. Finally we have observed a change in the flow of Newlin Creek in the <br />last few years. When it is flowing much if not all of the flow disappears into the ground. It used to do this <br />years ago farther east, but this seems now to happening more to the west. Obviously we can't demonstrate this <br />until there is water flowing. <br />I have communicated all of these concerns to George, and I have told him that I have asked for your advice. <br />WD Corley, Jr. <br />Sent from my iPad <br />On Nov 21, 2011, at 2:49 PM, "Binns, Janet" <Janet.Binns@state.co.us> wrote: <br />Good Afternoon Dr. Corley, <br />Thank you for the additional information. I have forwarded your e-mail to Yvonne Brannon in the <br />Inactive Mines Program ( vvonne.brannonPstate.co.us ). Based on the information you provided, we do <br />not know if the subsidence features you have noted are associated with the Southfield Mine or with <br />another mining operation. Someone from the Inactive Mines Program should be in touch with you, or <br />you may contact Yvonne. <br />javLet f gLLvi,A,s <br />Environmental Protection Specialist II <br />Colorado Division of Reclamation Mining and Safety <br />1 <br />