F/A-18 E/F Outlying Landing Field - 04/27/06

Background and Objective

BRRC has supported the Department of the Navy in its preparation of a Draft Supplemental Environmental Impact Statement (Draft SEIS) to provide additional analysis of potential environmental consequences associated with the construction and operation of an Outlying Landing Field (OLF) to support Field Carrier Landing Practice (FCLP) operations of F/A-18 E/F (Super Hornet) aircraft squadrons stationed at Naval Air Station (NAS) Oceana, Virginia and Marine Corps Air Station (MCAS) Cherry Point, North Carolina.

BRRC's efforts focused on three areas: ambient soundscapes, aircraft noise modeling, and waterfowl response to aircraft noise.

Process

Characterizing the interaction of ambient soundscapes with potential noise intrusions offers many challenges. The first challenge is one of perspective: sound level based or listener based. This paper will describe a sound level based approach for addressing the interaction between an ambient soundscape and introduction of man-made noise. For this approach, the ambient soundscape must be monitored for long periods of time to determine the average ambient sound levels and to assess the levels of transient noise events. In describing the ambient sound levels the sound data must be distilled into meaningful acoustical measures while retaining the complexity of the soundscape. Once the ambient soundscape is characterized, assessment of current or potential noise intrusions can be evaluated. This assessment requires detailed information of the intruding noise source for complete description of the interaction. This presentation will highlight this approach with examples from proposed military flight training near rural farming wilderness areas.

For the aircraft noise modeling, the supplemental analysis involved revising the modeled flight operations at each individual OLF site. This revision involved developing site-specific flight tracks and flight profiles that minimized potential noise impacts to surrounding communities and National Wildlife Refuge (NWR) areas. This report includes a description of the revised flight operations and the resulting Day-Night Average Sound Level (DNL) contours, along with additional noise descriptions from the proposed flight operations. Based on the refined operational description for each proposed OLF, noise analyses were conducted for each site to describe the proposed change in the acoustical environment in and around the proposed sites. This noise analysis involves long-term noise estimates, along with supplemental descriptions of the introduced aircraft noise.

An evaluation of migratory waterfowl responses to military aircraft flights in northeastern North Carolina was also conducted during this supplement analysis. The objectives of the noise response evaluation were to 1) characterize the noise experienced by waterfowl during Super Hornet flight operations at an OLF, and 2) evaluate any responses of waterfowl to that noise and/or associated visual stimuli. Part of this objective included six separate flight trials at OLF C to observe the waterfowl responses to the introduced Super Hornet operations. BRRC was supported this evaluation by providing detailed analysis of the physical acoustical environment and the aircraft noise used to assess the responses of waterfowl to the aircraft noise. During each flight trial, sound level meters (SLM) were located near the proposed runway site and near waterfowl observation points. These field measured data were combined with modeled aircraft noise to provide a reasonable estimate of the noise experienced by the observed waterfowl from these flight trials. The model employed was the Noise Model Simulation, NMSim (Ikelheimer and Plotkin, 2005), which is an advanced acoustical model. These estimated noise exposures were provided to Ecology and Environment for the assessment of the waterfowl response to the Super Hornet flight trials.

Prime: Ecology and Environment, Inc. Contractor: Wyle Laboratories - Test, Engineering and Research Group Sponsor: Naval Facilities Engineering Command and US Fleet Forces Command