Environmental Impact Statement Establishment Of The Gandy Range Extension And Adjacent Restricted Airspace As An Area For Supersonic Flight Training Hill Air Force Base Utah

The action being assessed is to establish airspace in the present Gandy Range Extension Military Operations Area/Air Traffic Control Assigned Airspace Area (MOA/ATCAAA) and adjoining restricted airspace for conducting supersonic flight training. Supersonic flights will be limited to elevations above 5,000 feet above ground level. Military aircraft, primarily F-16 aircraft assigned to Hill Air Force Base, propose to fly up to 1,050 supersonic sorties each month in this airspace. The combination of the Gandy Range and the smaller adjoining restricted airspace are judged to be the preferred alternative considered in addressing the need for additional supersonic flight approved airspace. The most significant environmental impact associated with the proposed action is that due to the generation of sonic booms. The land area beneath the proposed airspace is predominantly BLM land, but does have an estimated 350 residents. Areas beneath the most active portions of the airspace should still experience A-weighted day-night sound levels of less than 65 decibels; levels generally accepted as being suitable for residential purposes. Past studies predict minimal impact on animals and future plans in the area.

The Air Force needs additional area to conduct supersonic flight training for aircraft associated with Hill Air Force Base, Utah. The preferred alternative to meet this requirement is to designate an area of existing military airspace which is adjacent to the area currently used for supersonic flight for this purpose. The resulting supersonic area, a combination of the existing plus the proposed areas, would accommodate up to about 768 supersonic sorties per month. The existing area now accommodates a maximum of about 614 such sorties per month. Thus, the preferred alternative could result in an increase of about 150 supersonic sorties in an area about double the size of the area currently accommodating the 612 sorties. The new land area beneath the airspace is predominately BLM land, but does have an estimated 50 residents. If all 768 supersonic sorties were flown into this new area (a worst case which will not occur), it is estimated that any one spot on the ground would be subjected to one or more sonic booms per day only 35 percent of the time, and two or more sonic booms per day only seven percent of the time. As a result of public comments on the draft EIS, the Air Force substantially reduced the number of proposed additional sorties from about 400 to 150 per month, the number of people potentially affected from 350 to 50, and the land area from 2478 to 1360 square miles. The environmental impacts are summarized on the following pages.

The purpose of this document is to provide an information base on the effects of aircraft noise and sonic booms on various animal species. Such information is necessary to assess potential impacts to wildlife populations from proposed military and other flight operations. To develop this document the National Ecology Center conducted a literature search of information pertaining to animals and wildlife. Information concerning other types of noise was also gathered to supplement the lack of knowledge on the effects of aircraft noise. The bibliographic abstracts in this report provide a compilation of current knowledge. No attempt was made to evaluate the appropriateness or adequacy of the scientific approach of each study. (sdw).