Some east Columbia residents know from experience that planes flying to and from Baltimore-Washington International Airport are loud enough to drown out backyard conversations.
A few soon will be able to tell their neighbors precisely how loud the passenger jets and late-night cargo planes are -- thanks to portable noise monitoring equipment set up by the Maryland Aviation Administration's noise abatement division.
The division installed the first two of seven temporary noise monitoring stations planned for Columbia neighborhoods last week at residences in Long Reach village.
"We're not looking at it as a negative situation," said John Maitland, whose wife, Marilyn, requested the equipment. "We care about safety at the airport and its economic value. They're looking at alleviating problems for the public, and that's positive."
The sound equipment -- a microphone mounted on a tripod and attached to a computer -- will record noise 24 hours per day for a week to determine average daily levels.
The equipment is programmed to identify single events of noise above a certain threshold, which likely will be aircraft because "ambient noise" on the side streets is low, said division director Robert L. Talbert.
In July, about a dozen east Columbia residents annoyed by aircraft noise, particularly cargo planes, met with BWI officials and state Del. Virginia M. Thomas, District 13A Democrat, to discuss concerns and plans for the airport.
Long Reach resident Patrick O'Donnell said he requested the monitoring equipment to establish a baseline to compare noise levels today to those in three to five years.
He said he's concerned that BWI expansions will increase air traffic volume and affect noise levels in Columbia.
Construction has already begun on a BWI runway expansion that will accommodate more international air traffic, said BWI planner Mike West.
About 3 percent annual growth in traffic is anticipated, he said.
Noise from aircraft is "not too unacceptable" now, Mr. O'Donnell said.
He volunteered to have the equipment in his yard so a record could be developed for the community, and because he is concerned about the effect of noise pollution on property values, he said.
"No one at the meeting could say what our noise level was several years ago. There's no history there," he said.
Noise readings are used to analyze how changes in flight patterns affect noise levels; to evaluate noise abatement efforts; and to review BWI's adopted noise zone, where abatement measures such as soundproofing and property acquisition are taken. It's also used to compare actual noise levels to computer-generated models for specific areas.
The current 12,100-acre airport noise zone, within which certain land uses are considered incompatible, is being revised this year.
The proposed zone extends just across the Howard-Anne Arundel border at Dorsey, about three miles from the Kendall Ridge neighborhood in Long Reach. Kendall Ridge is about eight miles from BWI.
Mr. Talbert said he anticipates the readings for Ldn, or cumulative day/night sound level -- a measurement of 24-hour sound -- at the Columbia residences will range from the high 50s to low 60s. The outer edge of BWI's noise zone is 65 Ldn. Ambient noise levels probably will register in the low 40s, and single noise bursts from aircraft in the 70s to 90s, he predicted.
Air carrier jet departures from BWI average 168 daily, with about 20 percent, or 34, flying over Columbia, Mr. Talbert said. Arrivals flying over Columbia might be slightly higher, he said.
Ms. Thomas wrote to state transportation Secretary O. James Lighthizer asking whether an 11 p.m. curfew could be placed on cargo plane departures.
He responded that a curfew couldn't be imposed because cargo operators transport items crucial to the state's economy and to medical needs at night, adding restrictions only on freight aircraft could be discriminatory.
Federal regulations require commercial airlines to phase in planes that have more technologically advanced, quieter engines by the year 2000, Mr. Lighthizer wrote.
MAA will conduct a public hearing at 7 p.m. Oct. 26 at Glen Burnie High School, 7550 B&A; Blvd. SE, on the proposed BWI noise zone and changes to the noise abatement plan. Requests to present testimony should be sent to Robert L. Talbert, Director, Aviation Noise and Abatement Office, Maryland Aviation Administration, P.O. Box 8766, BWI Airport, Md. 21240.