2009-10-29_REVISION - C1982056

• Permit No: C1982056
• IBM Index Class Name: REVISION
• Doc Date: 10/29/2009
• Doc Name: Response & Revised Page Letter ‎(Emailed)‎
• From: Jerry Nettleton
• To: Tom Kaldenbach
• Type & Sequence: PR8
• Email Name: JHB
• Media Type: D
• Archive: No

To ensure compliance with 2.05.6(6)(f)(iv), please add to the permit application a description of the measures to be
taken to mitigate the effects of any material damage or diminution of value or foreseeable use of lands which occur.
Tom
From: Nettleton, Jerry [mailto:[e-mail]]
Sent: Thursday, October 29, 2009 1:22 PM
To: Kaldenbach, Tom
Cc: Binns, Janet; Berdine, Mike; Cowman, Scott; Thompson, Rocky
Subject: FW: PR09-08 Technical Adequacy Response III
Tom -
You were correct, attached is the revised information -
Regards,
Jerry
From: Thompson, Keith [mailto:[e-mail]]
Sent: Thursday, October 29, 2009 1:18 PM
To: Nettleton, Jerry
Subject: RE: PR09-08 Technical Adequacy Response III
Yes, the K for the Twentymile Sandstone should be 1.4x10-2. 1 had used the value for the Trout Creek Sandstone for the
calculations. The correction substantially shortens the time frame for the spread of drawdown outward from the mine
area. A revised copy of the text is attached. I still believe the simulated conditions are highly unlikely to occur, for two
main reasons: 1) the propagation of subsidence fractures through the overburden is so unlikely beyond a couple hundred
feet above the mine, and 2) even if subsidence fractures did propagate all the way up through 670 feet of overburden
(which includes 590 feet of marine shale), the chance of the fractures in the marine shale staying open long enough to
allow the Twentymile Sandstone to drain into the mine is extremely small.
Please call or email me with any other questions or concerns. Thanks.
Best regards,
Keith
Keith Thompson, P.G. I Sr. Project Manager
Direct: 970.304.0140 1 Cell: 307.259.7824 1 Fax : [phone]
Tetra Fech Complex World, Clear SolutionsT
1949 26th Ave Ct I Greeley, CO 80634 www.tetratech.com
3801 Automation Way I Fort Collins, CO 805251 wvvw.tetratech.com
PLEASE NOT E: This message, including any attachments, may include privileged, confidential and/or inside information. Any distribution or use of this
communication by anyone other than the intended recipient is strictly prohibited and may be unlawful. If you are not the intended recipient. please notify the sender
by replying to this message and then delete it from your system.
From: Nettleton, Jerry [mailto:[e-mail]]
Sent: Thursday, October 29, 2009 12:57 PM
To: Thompson, Keith
Subject: FW: PR09-08 Technical Adequacy Response III