Beaufort County officials say they'll consider building a berm or noise wall along the Hilton Head Island Airport, but are uncertain whether doing so would comply with federal guidelines.
The Hilton Head Town Council made the request after a meeting May 30, in which Palmetto Hall and Baygall residents, as well as members of St. James Baptist Church, requested a noise buffer between the county-owned airport and their properties. They say tree-cutting at the airport has left them more exposed to plane noise.
Hilton Head Mayor Drew Laughlin sent a letter June 4 to Beaufort County Council Chairman Weston Newton asking the county to consider erecting a noise wall north of the runway along Beach City Road as commercial property abutting the airport is removed for a planned runway extension.
"Council has simply decided the right thing to do is to support efforts to obtain an effective visual and noise barrier," Laughlin said Thursday.
His letter says a berm or wall could be paid for as part of negotiations by the county for easements needed from residents to cut trees that officials say pose a hazard for pilots.
A Federal Aviation Administration spokeswoman has said the county could apply for federal money to build a berm or noise wall if noise levels exceed accepted FAA thresholds. Previous studies at the airport, however, do not indicate that is the case, according to an airport master plan.
The FAA sets a threshold of 65 decibels for residential areas near airports, based on average ambient day and night noise levels over the span of a year.
In comparison, a typical conversation is 60 decibels. A vacuum cleaner or pickup truck is about 70 decibels. A door bell or garbage disposal is about 80 decibels, according to the airport master plan prepared by consulting firm Talbert & Bright.
The master plan indicates noise will increase slightly after the runway is extended, because of increased use by heavier, louder aircraft.
Lengthening the runway also would extend the airport's 65-decibel "noise footprint" to surrounding commercial property. That property, however, is already eyed for purchase or the airport would control by easement. Other nearby land is undeveloped. Therefore, all land uses beside airport property would be considered compatible and would not require a berm or wall under FAA guidelines, according to the master plan.
The FAA also prohibits berms and noise walls within designated safety areas and obstacle-free zones at the ends of runways, which could restrict placement on airport property.
"We've got some FAA issues that have to be considered as to where a berm or barrier could be located," Newton said Thursday. "But I believe there is a sincere effort to minimize the impacts on residents, and we'll explore any and all opportunities to do that."
The county will undertake another airport noise analysis as part of a required environmental assessment to extend the runway, county airports director Paul Andres said. That environmental study is under way.
The town and county paid for a separate noise study of the area in 2010, before trees were removed at the airport to meet FAA safety guidelines. Noise levels also will be recorded after all tree obstructions, including off-airport, have been removed and replanting is completed, Andres said.
Some have questioned the effectiveness of a wall or berm, arguing most noise affecting airport neighbors comes from flying aircraft, not noise on the ground. Others argue the loudest noise comes from jets forced to "rev" their engines to full throttle to take off on the short runway.
"The issue will likely be discussed over the course of the summer," county administrator Gary Kubic said. "There's a lot of questions that need to be answered and details to potentially flesh out. Paying for it will be a key question. Will the FAA contribute? Can the airport pay for it? Should county taxpayers pay through borrowing? Will the Town of Hilton Head contribute? And will it work?"
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