REV95048

• Permit No: C1982057
• IBM Index Class Name: Revision
• Doc Date: 12/22/2003
• Doc Name: Stipulation Responses
• From: DMG
• To: Seneca Coal Company
• Type & Sequence: TR45
• Media Type: D
• Archive: No

abrupt slope transitions in the pre-mine (presumably structurally controlled). There
are a higher number of such abrupt slope transitions in the revised PMT. Due to the
unconsolidated and generally uniform nature of the spoils, these abrupt slope
transitions would represent potential "nick-points", where head-cutting erosion
might be anticipated. Potential nick-points at 2050 (7.8%:14.9%), 2220
(1%:7.8%), 2700 (3.9%:12%), 3960 (4.9%:15.7%), and 4650 (1%:12%).
The currently approved PMT does not have the pronounced mid-slope convexity of
the revised PMT, nor does it have the abrupt slope increases at the lower end of the
profile. The revised PMT profile would appear to be less stable geomorphically than
the approved PMT profile, due to the apparent nick-points and the mid-slope
convexity. Compliance with design specifications 1 and 7, and possibly other
geomorphic specifications listed on revised page 10, as well as geomorphic
provisions of Rule 4.05.4(4) is questionable. Please amend the Exhibit to conform
with applicable geomorphic criteria of 4.05.4(4) and design specifications listed on
narrative page 10.
006-NE1 Gulch
15. Similar to 006 Gulch, the pre-mine profile is concave, whereas the revised PMT
profile has a distinct convex section mid-slope in the vicinity of 1700 to 2100 feet.
Lower segments of the revised PMT profile are significantly steeper than pre-mine.
There are potential nick-points at 1900 (9%:20%1 and near the very lower end of
the drainage at 100 (3.3%:13.2%).
The currently approved profile is relatively straight with a concave lower segment,
and no apparent abrupt slope transitions. The revised PMT profile would appear to
be less stable geomorpically than the approved PMT profile, and compliance with
geomorphic design specifications on revised page 10 and regulatory requirements of
4.05.4(4) is questionable. Please amend the Exhibk to conform with applicable
geomorphic criteria of 4.05.4(4) and design specifications listed on narrative page
10.
006-E1 Gulch
16. Pre-mine, current PMT and revised PMT profiles are broadly similar, in that each
exhibits straight to concave upper and middle segments, with a convex segment of
varying length and gradient near the lower end of the profile. The revised PMT
profile would appear to be an improvement over the currently approved PMT profile,
due to significantly reduced slope gradient at the lower end of the profile. However,
the remaining convexity at the lower end of the profile (beginning at approximately
1300 feet) and associated potential nick-points at 1300 (3.6°h:7.7%), 840
(1 %:12%), and 360 (8.1 %:14.8°k) would appear to conflict with the geomorphic
design specifications of page 10 and the regulatory requirements of 4.05.4(4).
Please amend the Exhibit to conform with applicable geomorphic criteria of
4.05.4(4) and design specifications listed on narrative page 10.
006-E2 Gulch
17. There was no pre-mine drainage that directly corresponds to this postmine drainage,
so there is no pre-mine profile. Both approved PMT and revised PMT profiles have a
mildly convex upper segment, a short lower gradient mid-slope segment, and a