APPCOR12007

• Permit No: C1981053
• IBM Index Class Name: Application Correspondence
• Doc Date: 6/26/1986
• Doc Name: BLUE FLAME SUBSIDENCE MONITORING
• From: MLRD
• To: PETER O CONNOR
• Media Type: D
• Archive: No

_ ,:
Richard D. Lamm
Governor
DATE
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DEPARTMENT OF NATURAL RESOURCES
David H. Getcnes, Executive Director
MINED LAND RECLAMATION DIVISION
DAVID C. SH ELTON, Director
June 26, 1986
T0: Peter O'Connor
FROM: Steve Renner
RE: Blue Flame Subsidence Monitoring
P ~v ~ ev.)
As per your request, I have reviewed the Subsidence Monitoring Plan submitted
for the Blue Flame Coal Mine. The information and proposed monitoring plan is
somewhat deficient as presented. Therefore, I have tabulated below rqy
concerns and comments.
No information pertaining to an expected angle of draw has been
presented by the applicant. The Division has determined that a prudent
worst case angle of draw for the Mesaverde Group is 21°.
By using a 21° angle of draw, and a maximum overburden thickness of 300
feet, it may be reasonably expected that subsidence features will be
expressed on the surface up to 115 feet away from the barrier pillar
after mining is completed. The permit boundary or the aerial extent of
extracted coal must be modified to ensure that a minimum of 115 foot of
subsidence buffer is established between the face of the barrier pillar
and the edge of the permit area. This is necessary, as the mine cannot
allow subsidence to occur off the permit area.
The applicant has not identified what, if any, renewable resources
exist above the permit area. The applicant should submit a detailed
map which overlies the mine plan. This map should accurately depict
topography, existing roads, the Huntington Ditch, ephemoral drainages,
any existing structures, and the subsidence monitoring points as
described in (3) and (4) below. This map must be certified by a
registered professional engineer.
3. The proposed subsidence monitoring stations must be modified to
accurately quantify movement. The proposed southern most point
(point 2) should be moved about 200 feet west, so it will not be
affected by the abandoned workings of the old mine. A fourth
monitoring point (point 1) should be established about 250 feet east
the west permit boundary line and about 110 feet north of the south
permit boundary line. The northern most monitoring point (point 4)
should be moved about 350 feet west of the proposed location. Point
the north western most point, will not be changed from the proposed
location.
of
3,
423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. [phone]