Technical report on sound levels in Bryce Canyon National Park and the noise impact of the proposed Alton coal mine: Response to technical criticism by Bolt Beranek and Newman Inc

Foch, James

On or about June 4, 1980, I was asked by the Region VIII office of the US Environmental Protection Agency (EPA) to make sound level measurements in Bryce Canyon National Park. At that time a National Park Service (NPS) contractor was assessing the impact of proposed surface coal mining, especially blasting, on tall columnar rock structures called HooDoos. The above ground blasts which were detonated by the NPS contractor near the Park were heard many mile away, and ensuing complaints alerted regional EPA, NPS and Office of Surface Mining (OSM) officials to potential noise impacts from the proposed coal mine. My colleagues at EPA and I agreed that measurements and tape recordings of blasts were desirable, and that some indication of the indigenous sound levels in the Park should be sought. It was clear to us that the indigenous sound levels would be important for assessing the significance of the blasting sound levels, because the indigenous levels might mask or cover up the blasting levels in some parts of the Park. I realized that equipment noise from the very large trucks and other machines used in surface mining might have a significant impact on the Park. Three factors are considered or at least mentioned in most environmental noise analyses: mining sound sources, effects along the sound propagation path to the Park, and the existing sound environment in the Park. Another factor was considered: audibility of mining sounds in the Park. The remainder of this document is a response to technical criticism of the report by the acoustical consulting firm of Bolt Beranek and Newman, Inc. (BBN, 1982).