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5.8.4 Measures for Release
An ERRCP has been prepared for the Bull Hill Mine (see Appendix I). It provides employees
and managers with specific instructions that will allow them to respond quickly and efficiently to
any foreseeable emergencies likely to occur. The ERRCP was developed using recognized and
accepted methods and practices. Prior to mine start-up, ERRCP details concerning specific
responses, protocols, and management contact information will be updated to reflect actual site
conditions.
5.8.5 Design Features/Environmental Protection Measures
RER has not identified any additional design features/environmental protection measures to
reduce potential impacts from hazardous substances.
5.9
SOILS
5.9.1 Baseline Soils Description
Soils found in the Project Area are typical of natural degradation and decay of igneous,
metamorphic, and sedimentary rock. The soils are generally expressed as thin alluvial, residual,
and colluvial deposits over bedrock mountain slopes. The soil units are reflective of the unique
geologic unit and variable parent material within this area. Deposition of soil material is also
reflective of the greatly varying topographic setting of the Bear Lodge Mountains.
The majority (approximately 50 percent) of soil within the Project Area is mapped by USDA as
Grizzly-Virkula complex, 15 to 60 percent slope soil map unit (NRCS, 2011). These soils are
alluvial derived from igneous and metamorphic rock found at elevations ranging from 5,000 to
7,000 ft. The Grizzly soil unit has a shallow depth of 0 to 1 inch and consists of slightly
decomposed plant material, 1 to 18 inches is very channery loam, 18 to 53 inches is very
channery clay loam, and 53 to 67 inches is very flaggy clay loam (NRCS, 2011). The Virkula
differs because from 1 to 14 inches it is silt loam, from 14 to 28 inches it is clay loam, and from
28 to 61 inches it is gravelly clay loam. The Grizzly-Virkula complex is found in the higher
elevations within the majority of Sections 16 through 21.
Adjacent to this soil complex, and comprising 17 percent of the Project Area is the Grizzly-
Virkula complex, 6 to 15 percent slope soil map unit (NRCS, 2011). This unit is comparable to
the aforementioned soil complex although this unit is found at elevations of 3,600 to 6,200 feet
and on moderate slopes.
The Larkson-Lakoa loams, 3 to 10 percent slopes soil unit is found in the northeast corner of the
study area and comprises approximately 8.5 percent of the soil in the Project Area (NRCS,
2011). This complex is found on gentle slopes formed by residuum and alluvial processes,
weathered from sandstone and shale. This unit is very deep and well-drained and is generally 0
to 1 inch slightly to moderately decomposed plant material, 1 to 23 inches loam/clay loam, and
23 to 61 inches clay/clay loam (NRCS, 2011). This unit is prone to saturation in periods of heavy
moisture. Adjacent to this unit is the Larkson-Lakoa loams, 10 to 60 percent slopes soil unit.
These units share the same characteristics although they are found at varying slopes.
Found in the southeast corner of the Project Area, covering 5 percent of the overall area, is the
Peso-Paunsaugunt complex, 6 to 10 percent slopes soil unit. This unit is found at elevations
from 7,200 to 9,000 feet and is found on the ridge that Peterson Spring and Big Flat Spring are
located. This soil unit is residuum and/or alluvium weathered from limestone and sandstone.
The Peso component has a profile that is generally 0 to 1 inch slightly decomposed plant
material, 1 to 31 inches is very channery silt loam, and 31 to 61 inches unweathered bedrock
(NRCS, 2011). The Paunsaugunt profile is 0 to 8 inches loam, 8 to 12 inches very channery
loam, and 12 to 60 inches unweathered bedrock.
