GENERAL55593

• Permit No: C1980004
• IBM Index Class Name: General Documents
• Doc Date: 12/31/1996
• Doc Name: PROPOSED DECISION & FINDINGS OF COMPLIANCE FOR RN4
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

Twelve (12) to eighteen (18) inches of soil were salvaged from the sediment pond and
riprap stockpile area, and 24 inches of soil were salvaged from the office area. A 12
inch depth will be salvaged from the Rivra Gravelly Sandy Loam Variant and a 24 inch
depth will be salvaged from the Glendive Sandy Loam to be affected by construction of
the McClane to Munger haul road. A small area of Havre Loam, saline phase, will be
disturbed but topsoil will not be salvaged because surface horizons below a depth of 1.5
inches exhibit sodium adsorption ratios (SAR's) which are excessive for reclamation use,
and as such, the Havre Loam does not qualify as topsoil pursuant to Rule 4.06.2(2)(b).
The thin surface layer could not practicably be salvaged without incorporating
underlying unsuitable soil material.
Information in Tables 4.4-1 through 4.4-6 documents the suitability of affected soil
types by horizon. Upper horizons of the affected soil types are generally good growth
media, with the exception of the Havre Loam, which exhibits SAR values in excess of
40, within each sampled horizon below a depth of 1.5 inches.
Because no topsoil was salvaged initially, portions of the reclaimed mine bench
access/haul road may not be topsoiled upon final reclamation, and the mixed soils and
overburden material in the bench and outslopes would be used as plant growth medium
for final reclamation. Section 4.4.5.4 summarizes evaluation of the surficial and
subsurface bench materials required by the Division through stipulations attached to the
1982 and 1985 permit approvals. Analyses submitted in response to the stipulations
demonstrated that the material would be suitable for plant growth, and that no special
handling would be required.
Upon final reclamation, topsoil will be re-spread to a minimum depth of 18 inches along
the McClane to Munger haul road, 24 inches in the office area, and 4 to 8 inches on
other post-law disturbance areas and approximately 1 acre of the mine bench. Sediment
removed from the sedimentation pond and stockpiled adjacent to the pond appears to be
suitable plant growth material based on visual assessment and plant growth which it
currently supports. Pond cleanout material will be approved for use as topdressing on
pre-law disturbance areas upon submittal of chemical and physical analyses
demonstrating its suitability. The following stipulation is necessary.
STIPULATION NO. 27
SEDIMENT REMOVED FROM THE SEDIMENT POND MAY BE USED AS
A TOPDRESSING OR TOPSOIL SUPPLEMENT PURSUANT TO RULE
4.06.2(4)(a), UPON SUBMITTAL OF CHEMICAL AND PHYSICAL
ANALYSES DEMONSTRATING THAT THE MATERIAL IS EQUAL TO OR
MORE SUITABLE FOR SUSTAINING VEGETATION THAN AVAILABLE
TOPSOIL OR OTHER PLANT GROWTH MEDIA. SUCH DEMONSTRATION
SHALL BE BASED ON A REPRESENTATIVE COMPOSITE SAMPLE OF THE
MATERIAL OBTAINED FROM EACH POND CLEANOUT EPISODE.
REQUIRED PARAMETERS WILL INCLUDE THOSE LISTED IN 4.06.2(4)(a),
WITH THE EXCEPTION OF THICKNESS, DEPTH, COARSE FRAGMENTS,
22