Navy releases 2009 ACUS update for Patuxent River; county officials discuss noise contours and land‑use compatibility

Naval Air Station Patuxent River presented a revised Air Installation Compatible Use Zones (ACUS) study to the Saint Mary's County Board of County Commissioners on Nov. 10, 2009, outlining updated noise contours, accident potential zones and recommendations for compatible land use around the base.

The Navy formally approved the study in September 2009 after a multi‑year effort that began in 2007 and incorporated flight‑operation and aircraft‑mix changes, including data related to the F‑35 and increased unmanned aircraft activity. "The purpose this morning is to explain the new revised ACUS study, that the Navy has approved in September of this year," said Captain Andy Maasico, who led the Navy presentation.

Why it matters: county and Navy officials said the revised noise and safety data will guide local planning, zoning and construction decisions near the base. The study reports that day‑night average sound level (DNL) contours have changed since a 1979 study and that the most extreme noise contours (75 dB DNL and above) remain within base property. Captain Maasico explained the DNL metric and that it adds a 10‑decibel penalty for operations between 10 p.m. and 7 a.m., and noted that "all of the contours 75 dB or greater are within the physical confines of the installation."

The ACUS study used the Navy's NoiseMap 7.2 model to project 5‑year noise impacts, producing DNL contours at 5‑decibel increments. The presentation compared 1979 and 2009 contours and showed increases in the 60–65 dB and 65–70 dB ranges in parts of Lexington Park and over Solomons Island in neighboring Calvert County. "You will note... we do see increases in all of the noise zones," Maasico said, adding the changes were driven by shifts in aircraft types and operations.

The Navy also described accident potential zones (APZs). The presentation noted APZs are based on historical accident statistics and are concentrated along runway centerlines. "APZs do not reflect the probability of an accident," Maasico said, and the county was told there was no expansion of APZs off base compared with the 1979 map; minor increases were internal to Navy property or extended over water.

County planning staff and commissioners asked how the study would be used locally. Derek Berlage of the county's Land Use and Growth Management office said the noise contour data could be used to consider a noise‑attenuation zone that would not change permitted land uses but could require construction techniques to reduce indoor noise. "That data unfortunately came out too late for the planning commission to consider it, but it still may be brought to your table," Berlage said.

Commissioners and presenters emphasized the ongoing partnership. Commissioner President Russell praised Navy cooperation, and county officials said the study would be useful for the county's comprehensive plan and zoning work. The Navy noted its outreach and recent efforts on noise abatement procedures, such as briefing aircrews on flight tracks and weekend operation limits. The Navy also said it maintains a noise complaint hotline and averages roughly 80–90 complaints a year nationwide for the installation; the Navy indicated it investigates complaints and correlates them with flight‑track data.

Next steps: planners said they will consider whether to adopt a local noise‑attenuation policy and will use the study in comprehensive planning and the rezoning process. County and Navy officials said they will continue semiannual meetings to address encroachment, land use and related issues.

Evidence: presentation material and remarks from Capt. Andy Maasico, Leroy Mattingly (ACUS manager), Rick Owen (Naval Facilities), and county planning staff were given to the commissioners during the Nov. 10 meeting and are on file with the county.