U.S. Air Force releases final impact report for Powder River expansion; decision expected before Jan. 1

Residents of southwest North Dakota and eastern Montana expressed great concern in the four years since the announcement of a proposed expansion to the military aircraft training area known as the Powder River Training Complex.


by BRYCE MARTIN | N.D. Group Editor

Residents of southwest North Dakota and eastern Montana expressed great concern in the four years since the announcement of a proposed expansion to the military aircraft training area known as the Powder River Training Complex.

The controversial plan had many area farm owners and aviation experts urging the federal government not to follow through on the project.

The time for public input has since ended and a formal decision on whether to go ahead with the expansion is expected later this month.

But prior to the U.S. Dept. of Defense’s final word on the matter, and after four years and an exhaustive public comment phase, the U.S. Air Force released a Final Environmental Impact Statement on Nov. 24. The report detailed a final modified expansion area and the potential impacts such an expansion could cause.

Plans call for Powder River, which currently spans South Dakota, Wyoming and Montana, to grow into an 18-million acre bomber-training complex that would also reach into southwest North Dakota, from Bowman to Hettinger and up to New England.

U.S. Air Force crafts from Minot Air Force Base and Ellsworth Air Force Base in Rapid City would utilize the area for exercises nearly five days each week and, 10 to 12 days of the year, host large force exercises, colloquially known as war games, across the stretch.

The Air Force’s Modified Alternative A would expand the current Powder River operations area, located in western South Dakota, into four separate low and high military operations areas (MOA) for daily training.

It is this alternative that the U.S. Air Force favors most.

The most pressing issue facing the area is the altitude at which several of the military’s aircraft could fly, notably over Bowman, which has been designated in the plans as a low/high area where crafts could fly at a minimum of 500 feet above the ground.

Other airspace encompassed by the expansion, such as Hettinger’s, has been designated as high areas, meaning aircraft could only fly as low as 12,000 feet above the ground.

The Air Force conducted 19 public hearings since the original draft of an environmental impact statement in 2010. Issues and concerns identified during the hearings were reviewed by the Air Force and the Federal Aviation Authority.

The release of the final impact report gives explanation and mitigation on some of the larger issues brought forth by landowners, farmers and governing representatives, considering impacts such as noise, land use, wildlife and general aircraft safety.

Sen. Heidi Heitkamp said last week that she is hopeful for the Powder River expansion, but would help ensure that the Air Force “keeps their promises.”

“We need to also make sure the Air Force keeps its promise to limit the impact of the expansion on our communities, businesses, local airports, pilots, ranchers and tribes who rely on our land and unobstructed air space to do their jobs,” Heitkamp said in a statement.

Heitkamp worked with the Air Force to ensure any work it does to expand air space at the Powder River Training Complex would not negatively impact interests of surrounding communities.

Noise only an ‘annoyance’

The public expressed extensive concern about aircraft flying too low to the ground. Impacts from such an event include uncertainty, startle effects and noise.

According to the report, the Air Force would continue the process within the Powder River MOAs whereby ranchers have coordinated with the Air Force to identify temporary avoidance areas to reduce the potential for low altitude aircraft impacts.

The Air Force claimed that the overall resulting noise impact from bombers and other aircraft operating within the expanded Powder River training area would only be considered an “annoyance” to persons on the ground, and not significant enough to warrant larger mitigations, according to the report.

For low fly areas such as Bowman County, however, noise could be a bigger problem.

“Increased noise from a sudden low overflight would be noticed and could be perceived as a significant impact by residents under the airspace,” the report said.

Such an overflight would be expected to occur over two to four percent of each active MOA during each training day, or an average of six to nine per year, according to the report.

Supersonic flights emitting sonic booms, the sound made from traveling faster than the speed of sound, would be limited to 10 days per year and could average at least one sonic boom per day.

A boom could result in a local area experiencing an overpressure. If that occurs, glass, plaster and other structural elements in good condition normally would not be expected to fail, but it would be possible, according to the report.

Sudden onset sounds can be startling to humans and animals and have resulted in damage to penned cattle and fencing—one of the main negative aspects identified by public input.

The Air Force would extend the Powder River airspace policy of establishing seasonal avoidance areas to reduce potential impacts to ranching, other sensitive areas and cultural or historic resources.