PM10 dust project

Commercial coal mines in the Powder River Basin of Wyoming, US, have been operating and monitoring ambient air dust levels for over 25 years. Until 2001, no applicable dust compliance level was ever exceeded. However, the short term PM10 (dust particles under 10 microns) health standard of 150 μg/m3 was exceeded four times during 2001.

In response to this situation, Rio Tinto's Kennecott Energy has worked to develop a coalition of interested parties, including the oversight regulatory agency, the Wyoming Mining Association, the Petroleum Association of Wyoming, the Campbell County Commissioners, and the coal, oil, natural gas and coalbed methane companies active in the areas of the exceedences.

Speciation tests on the dust involved indicated that 65 per cent to 92 per cent of the dust was most likely to have come from unpaved county roads near the monitors, and the non mine traffic using those roads. The increasing trend in dust levels can be partially correlated with increased oil production and coalbed methane production activity in the region. While some increase in PM10 dust is likely to be attributable to increasing coal production and overburden movement, dust suppression activities at the mines have also increased in proportion to production. The only dust monitors in the region are located at the mines.

An outcome of the coalition of interested parties is that the county, with financial assistance from Kennecott Energy and another coal company, has applied dust suppression treatment to several miles of county road in the vicinity of monitors. Additionally, an active taskforce has formed between coal and coalbed methane interests and the respective trade associations, to fund additional treatments and to develop longer term solutions to dust from non coal sources. This is an example of establishing a broad stakeholder base in response to an untenable environmental situation.