GENERAL37691

• Permit No: C1981026
• IBM Index Class Name: General Documents
• Doc Date: 8/1/1991
• Doc Name: Proposed Decision & Findings of Compliance for SL2
• From: Phase II
• Permit Index Doc Type: FINDINGS
• Media Type: D
• Archive: No

PROPOSED DECISION - Canadian Strip/Phase II Bond Release
August i, 1991
Page 2
The Division reviews topsoil replacement depths, erosion data and the
general geomorphology of the site, as well as vegetative cover and
species diversity data when evaluating a Phase II Bond Release Request.
A bond is calculated which would cover the costs to the Division to bring
an independent contractor on site to complete any remaining reclamation.
This bond includes a component for vegetation failure.
III. Evaluation
On September 5, 1990, a Phase II Bond Release Inspection was performed at
the Canadian Strip Mine. Cathy Begej led the inspection, and it was
attended by Dennis Byrnes, OSM-Albuquerque, Dave Harr and Gene Dilla
shave, Kremmling Office of BLM, Glenn Murdock, previous employee at
Canadian Strip and Jerry Koblitz, Greystone Development Consultants, the
permitting liaison for Wyoming Fuel Company.
The first condition which must be met for Phase II Bond Release concerns
erosional stability at a site, as defined by Rule 3.03.1(3>(b>. A site
should not contribute suspended solids to streamflow or runoff outside
the permit area in excess of pre-mining levels, as determined by baseline
data. Wyoming Fuel Company prepared a sediment loss analysis of the
sediment generated from a 10-year, 24-hour storm event using the software
package SEDCAD+, Version 3.0, and the Revised Universal Soil Loss
Equation (RUSLE> sub-routine. Vegetative cover information was derived
from baseline data from the reference areas and 1990 vegetation
sampling. The operator divided the reclaimed area into three watersheds,
coincident with the post-mining drainage and sediment ponds. The
analysis was run using three soil types: a composite of SCS sieve
analyses for soil types in the mine area; a composite texture from six
soil samples taken in upland areas of the reclaim and a composite texture
from two soil samples taken from sediment in the base of Ponds 1 and 2.
All runs in all watersheds showed lower sediment generation in the
post-mining situation, as summarized in Table 1. It should be noted that
these results reflect erosion protection provided by both vegetative
cover and total cover. At Canadian Strip, a wood chip mulch was applied
which still covers the site.
Hydrology and Sedimentology for a 10-year, 24-Hour Event
Table l: Summary of SEDCAD+ Results
Runoff Peak
Mining Volume Discharge Sediment
Watershed Situation (ac-ft) (cfs> (tons)
1 Pre- 2.06 12.61 12.8
1 Post- 1.90 15.26 3.3
2 Pre- 1.08 8.78 5.3
2 Post- 1.04 4.99 4.5
3 Pre- 0.22 2.25 1.1
3 Post- 0.05 0.45 0.1