REV99632

• Permit No: C1982057
• IBM Index Class Name: Revision
• Doc Date: 3/14/2006
• Doc Name: Adequacy Review Letter/Cost Estimate
• From: DMG
• To: Seneca Coal Company
• Type & Sequence: PR5
• Media Type: D
• Archive: No

This information would be helpful for field quality control of backflill
compaction.
7. Reference to use of roto-clear machine was properly deleted. Item Resolved.
8. The issue of topsoil replacement thickness has not been resolved. The cover letter
response to this item states that "...CDMG has suggested that SCC replace
varying thicknesses of topsoil", and that "SCC would rather leave the average
thickness as shown on the existing map". We note that the variable topsoil
replacement plan is not just a DMG suggestion, it is the currently approved plan,
as depicted on approved Exhibit 21-I, for the II-W South Mine Area. The
response letter further states that "SCC would rather let the variation occur
naturally rather than specify exact locations...".
Rule 4.06.4(2)(a) requires that topsoil "...be redistributed in a manner that
achieves an approximate uniform, stable thickness consistent with approved
postmining land uses, contours, surface water drainage systems, and requirements
of the vegetation proposed to be established". Tn recognition of the potential for
enhancement of vegetative diversity and woody plant establishment, the Division
has approved proposals that incorporate planned variation in topsoil replacement
thickness. Such plans are consistent with the provisions of 4.06.4(2)(a), as long
as the replacement thickness is "approximately uniform" within delineated areas
of defined average replacement thickness. The proposal referenced in the cover
letter to "let the variation occur naturally" lacks the necessary definition to assess
whether compliance with 4.06.4(2)(a) would be achieved.
As noted previously, we believe an appropriate compromise approach would be to
specify the standard average replacement thickness for most areas, with the
exception of specified tree and shrub establishment areas where soil would be
replaced in thicker or thinner layers as appropriate. The proposed plan already
indicates that afour-foot thickness will be replaced in aspen establishment areas
in the South Mine area. A lesser replacement thickness (6 inches) was approved
for upland shrub areas at Yoast Mine, and would be appropriate for the South
Area upland shrub areas at II-W as well.
Please consider these comments and submit appropriately amended text and
map, in compliance with 4.06.4(2)(a).
We note that currently approved narrative on page 31 of Tab 21 specifies a mean
topsoil replacement depth of approximately 1.3 feet for the II-W North Area, and
a mean replacement depth of approximately 1.7 feet for the II-W South Area, with
the variable replacement thickness zones as depicted on the current Exhibit 21-1.
Soi] replacement has been completed within the North Mine Area, with the
exception of the office/shop area, and various roads and support facilities.