Philadelphia International AirportFort Mifflin Sound Insulation

Feasibility Study

Presented to the:

American Association of Airport Executives7th Annual Airport Noise Mitigation Symposium

October 9, 2007

Introduction and Background

Fort Mifflin – “The Fort that saved America!”– In 1777 Fort Mifflin was the site of a fierce battle with the

British Navy during the Revolutionary War. – For six weeks this small fort held off the British allowing

George Washington time to build up his troops and defeat the British at Valley Forge.

– The Fort was destroyed during that battle, but was restored in 1779.

– The Fort was turned over to the City of Philadelphia in 1959.

– In 1970, Fort Mifflin was recognized as a National Historic Landmark.

Fort Mifflin is located just East of the airport and is impacted by noise from aircraft arriving and departing.

It is located within the DNL 70 dB noise contour, with some portions within the DNL 75 dB contour.

Single event noise levels can exceed 90 dB (3 feet away

from a lawn mower) depending on the type of aircraft and operational mode.

Introduction and Background

Fort Mifflin is frequently used for educational purposes. – Thousands of school children, Cub/Boy/Girl Scouts, and

other groups visit the Fort each year.

Because of the close location of the Fort to the airport, tours and presentations are frequently interrupted by aircraft noise.

Introduction and Background

Understanding the importance of Fort Mifflin to our nation’s history, the Division of Aviation chose, as a part of their first Part 150 Study, to recommend a feasibility study to determine if sound insulation treatments could be adopted at three buildings at Fort Mifflin.

In May 2003, the FAA approved PHL’s Noise Compatibility Program (NCP), and the mitigation measure for this study.

Introduction and Background

Providing sound insulation to Fort Mifflin is unique from your typical residential sound insulation programs at an airport because it is recognized as a National Historic Landmark.

Any modifications to a historic structure must ensure that the historic aspects of the structure are not compromised.

This required extensive consultation and coordination with the State Historic Preservation Officer (SHPO), Philadelphia Historical Commission, and National Park Service.

Introduction and Background

In developing the proposed treatment options, two principle strategies were adopted for treating architectural elements:– Minimize impacts to visible elements of the buildings that

are important to their architectural and historic character;– Match existing styles and materials, but with products and

materials that meet noise reduction goals. The first step in developing treatment options was to

determine the level of noise reduction that would be necessary and identify paths for noise to enter each building.

Project Approach

Project Approach

Each building underwent acoustical testing to measure exterior and interior noise levels to determine the Noise Level Reduction (NLR) needed.

Federal Aviation Administration (FAA) regulations require that the sound insulation of habitable spaces result in:– An interior noise level not greater than

DNL 45 dB;– Minimum noise level reduction of 5 dB

Photo: Richard McMullin

Project Approach

Building - RoomExterior

DNLInterior

DNLNLR (dB)

Restoration Hospital/Mess Hall 1st Floor Multi-Purpose Room

77 53 24

Restoration Hospital/Mess Hall 2nd Floor Offices

77 46 31

Soldiers’ Barracks Exhibit Rooms

77 51 26

Officers’ Quarters Exhibit /Caretaker’s Rooms

77 49 28

Restoration Hospital/Mess Hall

Houses the Fort’s administrative offices, a multi-purpose room, video conference lab, and a kitchen.

Windows and doors were found to be in fair to poor condition.

There are window air conditioners installed in several locations.

The chimney of the fireplace in the multi-purpose room is open.

Restoration Hospital/Mess Hall

Our team developed treatment options for the this building. The following were recommended.– Doors – Replace existing interior and exterior doors.– Windows – Install single glazed double hung windows

with glazed new storm windows w/ 7” air space.• Would reduce noise by 15 dB on 1st floor and 10 dB on 2nd floor

– HVAC – Install 3 split HVAC systems, 2 (2.5 ton) units for the 2nd floor and 1 (5-ton) unit for the 1st floor. Condensing units would be installed outside in the back of the building.

Restoration Hospital/Mess Hall

–Chimney – Install a damper on the chimney in the multi-purpose room.–Lighting – Replace the recessed lights in the ceiling since the holes create a noise path.–Attic Hatches – Replace the two attic hatches, on the 1st floor and 2nd floor, with sound insulating hatches.–Roof/Ceiling – Install one inch plywood on top of the attic joists to completely cover the attic floor.

Soldiers’ Barracks

One of the main buildings used for educational purposes and exhibits.

Sleeping quarters for overnight quests, such as the Scouts or war reenactment participants.

A meeting room is also located in this building, as well as, a workshop on the second floor.

Soldiers’ Barracks

The windows are double hung with a single glaze multi-lite sash and are in fair condition. They appear to be 20th century replacement products.

The doors are also in fair condition, with evidence of some deterioration. There are many gaps at the thresholds that allows noise to enter the building.

There are 3 independent, ductless, split package heat pumps within the building, which were found to be in fair to non-functional condition and a window air conditioner in the conference room.

The heating system and ventilation within the building was deemed to be inadequate.

Soldiers’ Barracks

Soldiers’ Barracks

– Doors – The ideal recommendation for the doors of this building was to reconfigure the vestibules to allow for the installation of a third door.

– This was not acceptable to the historical agencies.

The recommended treatment options included:

– The final recommendation was for the gaps that exist in the interior and exterior doors be weather-stripped and filled to prevent noise from coming through the gaps.

Soldiers’ Barracks

– Windows – Install single glazed double hung windows with glazed new storm windows w/ 7” air space.

• Would reduce noise by 13 dB on 1st floor

– HVAC – Install two split package systems with condensing units in the back of the building and two indoor fan coil sections in the attic.

Ductwork would be situated completely within the attic and new ceiling registers would be installed.

The conference room would include a new 1-ton ductless heat pump.

• This was least obtrusive to the overall building appearance, but

will require additional cost and structural engineering.

Soldiers’ Barracks

Other treatments recommended included:– Chimney – Dampers should be installed on all functional

fireplaces and non-functional fireplaces should be capped.

Officers’ Quarters

Rooms on the second floor are used for overnight guests and is the location of the on-site caretaker’s living quarters.

The first floor consists of various exhibits and storage rooms. Underwent renovations in the late 1980’s when new windows

and HVAC were installed.

Officers’ Quarters

The windows are double hung with a single glaze multi-lite sash and interior screens and are in fair to poor condition. – There is a very poor fit on the 2nd floor where the top sash overlaps

the bottom by 10”.

Officers’ Quarters

The doors are also in fair condition, except at the rear of the building where there is evidence of deterioration. – There are many gaps at the thresholds that allow

noise to enter the building.

The HVAC is provided by a split package with a fan coil mounted in the attic and an outdoor condensing unit. The system is nearing replacement age (installed in 1980’s).– There is a window unit in the caretaker’s quarters

to provide AC to this room without having to cool the entire building.

Officers’ Quarters

The recommended treatment options included:– Doors – Replace existing interior and exterior doors.– Windows – Install single glazed double hung windows

with glazed new storm windows w/ 7” air space.• Would reduce noise by 10 dB on 1st floor

– HVAC Option 2 – The attic ducts and the current equipment would be completely replaced with two smaller fan-coils in two zones.

• This will split the building capacity between the top floor and the bottom floor of the building, adding more flexibility in operation and making it more economical.

Officers’ Quarters

Other treatments recommended include:– Chimneys – The chimney in the rear exhibit room should

have a damper installed. The fireplaces on the 2nd floor should be capped if they will not be used in the future.

– Lighting – The recessed lights on the 2nd floor should be replaced.

– Attic Hatches – The two attic hatches on the 2nd floor should be replaced with sound insulating hatches.

Next Steps for Fort Mifflin

The study has shown that it is feasible to provide sound insulation treatment to the selected buildings at Fort Mifflin.

A final report has been prepared for the FAA for review and comment.

The recommended sound insulation program will be included as a new mitigation measure within the Part 150 Update, which is in progress, to receive funding for implementation.

Once the FAA has approved the measure, the DOA can obtain a grant to begin the implementation.