Aircraft Noise Study for Malmstrom Air Force Base

In support of an Environmental Assessment (EA), pursuant to the National Environmental Policy Act (NEPA), for the proposed beddown by the US Air Force (USAF) of eleven (11) Augusta Westland MH-139 helicopters, replacing eight (8) Bell UH-1N Huey helicopters, at Malmstrom Air Force Base (AFB), in Great Falls, MT, HMMH was subcontracted to prepare USAF-specified Noise Model Operational Data Documentation (NMODD) describing aircraft noise exposure for Baseline/No Action Alternative and the Proposed Action.

HMMH was responsible for all aspects of the aircraft noise study, including on-site operational data collection/validation, modeling and documentation. Modeling was accomplished with the Advanced Acoustic Model (AAM) and the legacy core program of the NOISEMAP suite (NMAP). AAM was used for flight operations. NMAP was used for static operations. Noise exposure was computed in terms of Day-Night Average Sound Level (DNL) for annual average daily operations. DNL contours of 65, 70 and 75 decibels (dB) were shown.