2009-10-29_REVISION - C1982056 ‎(2)‎

• Permit No: C1982056
• IBM Index Class Name: REVISION
• Doc Date: 10/29/2009
• Doc Name: Drawdown Calculations for Spring Areas Revised Page ‎(Email)‎
• From: Jerry Nettleton
• To: Tom Kaldenbach
• Type & Sequence: PR8
• Email Name: TAK
• Media Type: D
• Archive: No

Binns, Janet
From: Nettleton, Jerry [[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
Attachments: Drawdown Calculations for Springs Areas - revised to correct K.doc
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 Cell: 307.259.7824 1 Fax : [phone]
Tetra Tech I Complex World, Clear Solutions"
1949 26th Ave Ct i Greeley, CO 80634 www.tetratech.com
3801 Automation Way I Fort Collins. CO 805251 w,.vw.tetratech.com
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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
From: Kaldenbach, Tom [mailto:[e-mail]]
Sent: Thursday, October 29, 2009 12:56 PM