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5.0 ENVIRONMENTAL PROTECTION MEASURES
5.1
AIR QUALITY
5.1.1 Climate and Physiography
The Bear Lodge Mountains have a warm and relatively dry climate during summer, followed by
cold winters with variable amounts of snow. The Bull Hill Mine property lies within the Black Hills
National Forest, covering the crest of the Bear Lodge Mountains, a narrow northwest-trending
range situated in northeastern Wyoming. Physiographically, the mountains are a north-westerly
extension of the Black Hills uplift of western South Dakota. The range is characterized by
rounded grass and pine-covered mountains reaching an elevation of 6,400 feet within the
property.
The mountains have moderate slopes covered by western yellow (Ponderosa) pine and aspen
forest interspersed with dense thickets of brush. Narrow grassy meadows cover the upper
reaches of seasonal drainages. The lowest point within the Project Area is about 5,800 feet
elevation.
The climate of Crook County varies with topography. There are two major areas: the Bear
Lodge Mountains and the lower-lying foothills and plains area. Climatic data from the radar
station referenced in the Final Preliminary Assessment/Site Inspection Report, Former PM-1
Reactor (U.S. Air Force Air Combat Command/Earthtech, 2006) are used for the Bear Lodge
Mountains and are considered the most representative for the Project Area. The following
summarizes data from the radar station:
Average annual air temperature
43.6°F
Lowest recorded temperature
-42°F
Highest recorded temperature
105°F
Average annual precipitation
17.41 inches
Lowest annual precipitation
11.58 inches (1954)
Highest annual precipitation
25.38 inches (1964)
Average seasonal snowfall
64 inches
The average total precipitation in Sundance is 18.14 inches and the average total snowfall is
74.6 inches. Most of the precipitation occurs as thunderstorms during April through July. Winds
are generally from the west or northwest.
RER began collecting meteorological data at the AMS-2 station (shown on Map 5.1-1) in
November 2011.
5.1.2 Baseline Air Quality
The Wyoming Ambient Air Quality Standards (WAAQS) and National Ambient Air Quality
Standards (NAAQS) are health-based standards which define the maximum concentration of air
pollutants allowed at all locations to which the public has access. U.S. Environmental Protection
Agency (EPA) criteria air pollutants for which standards exist are carbon monoxide (CO),
nitrogen dioxide (NO
2
), ozone (O
3
), particulate matter less than 10 microns in effective diameter
(PM
10
), particulate matter less than 2.5 microns in effective diameter (PM
2.5
), and sulfur dioxide
(SO
2
). The Project Area is in attainment for all criteria pollutants, meaning that all NAAQS and
WAAQS are being met.
