Buildings Burned at Former Arsenal To Eliminate Any Trace of Explosives
features
Thirty-two buildings of a former Army explosives arsenal in Pennsylvania were burned as part of a unique decontamination program leading to future public recreational use of the area.
Although the buildings were found to be physically clean before the burn, they could conceivably have contained small but dangerous pockets of residual explosives in drains, walls and floor cracks. Only a specially planned fire could have eliminated all safety and health hazards.
The Frankford Arsenal, in the highly populated and industrialized northeast section of Philadelphia, had a 165-year history of research, design and manufacture of munitions. After being declared excess to the Army’s needs in 1976, the 110-acre facility was deactivated in 1977.
Although the arsenal is inactive, the United States Government must maintain round-the-clock security, including fire protection and ground maintenance, over the 216 buildings and equipment until all properties are certified clean from any reactive, corrosive or toxic substances or their by-products. After such certification, the arsenal will be turned over to the General Services Administration for public sale.
The area requiring special decontamination was just inside the protective stone walls of the arsenal. It contained a 9-acre parcel with 32 one-story block buildings of one and two rooms. Drains and sumps connected with a terra-cotta sewer system running 8400 feet. Several of these buildings were surrounded by reinforced concrete blast walls.
This particular area of the arsenal was known as the “400 group” because of the 400-series building numbers. It was constructed in the early ’40s and was used for the manufacture of explosive mixes, igniters, pyrotechnics and incendiary devices. Specific substances used at the site include barium nitrate, magnesium, aluminum powders, zirconium, tetrazene, lead styphnate, mercury fulminate, nitroglycerine, nitrocellulose, tetryl, cyclonite, antimony sulfide, and various nitrates, chlorates and perchlorates.
From arsenal to marina
Long-range plans for the 400 group area call for a public marina, recreation park and fishing facility to be constructed by the Pennsylvania State Fishing Commission.
To ready this area for its new owner, Rockwell International’s Energy System Group of Canoga Park, Calif., was contracted by the United States Army to decontaminate, clean up and demolish the 32 buildings, and the associated 43 drains and sumps along with the sewer system. Anthony F. Lillie, Rockwell’s site director, proposed two basic approaches for destroying the explosive residues: by fire and chemical decomposition.
Thermal decomposition of any explosive residue consists of raising the temperature of the material to its decomposition point. This would be in the range of 500°F for the materials expected to be present in minute quantities in the 400 group. Chemical decomposition could also be used where the explosives are found in small quantities, as in a laboratory, and the decomposition reactions can be continued for long periods of time.
Manufacturers of explosives have found through experience that the most effective method for disposal of explosives is burning. For cleanup of an explosives manufacturing facility, both the industrial and government sectors have long realized that burning the materials is also the best method for disposing of any residual materials. This is further documented in an Army regulation which permits unrestricted use of a contaminated combustible building only after burning.
Under complex field conditions involving the number of structures which existed in the 400 group, chemical decomposition simply could not be relied upon to destroy the explosive residues that were manufactured in the facility.
In addition, chemical decomposition would require the use of several thousand gallons of caustic chemicals and hundreds of gallons of highly flammable acetone. The toxic waste disposal of these chemicals in an environmentally acceptable manner would also be a formidable problem. Therefore, the tradeoff between thermal and chemical decomposition was based on safety and health considerations.
Continued on page 18
Photos by Rockwell International
Advance preparations
The Frankford Arsenal maintains its own fire department under the jurisdiction of Space Age Engineering Inc., a Burbank, Calif., firm providing security, fire protection and maintenance for many military installations. As the fire chief for Space Age at the arsenal, I had to provide considerable supplemental fire prevention and research data for the burn.
Prior to any burning, I proposed that all friable asbestos in the area—primarily the covering on external piping—be removed, packaged in accordance with applicable regulations and shipped to an approved burial site. The wooden walkways were taken down and all lumber and tar paper from the roofs was piled beside two blast walls. To reduce the potential of flying embers, the chain-link fencing which surrounded the 400 group was taken down and placed over the wooden piles. Then, all piping and conduits were removed and placed within the structures for burning.
To completely burn the individual structures, sumps and drains, Site Director Lillie placed approximately 18 inches of charcoal briquets wall to wall and saturated them with kerosine. Igniters consisting of an electric match, black powder and magnesium powder assembled in plastic bags, were made ready for remote detonation in sequence. It was estimated that approximately 300,000 pounds of charcoal briquets and 2500 gallons of kerosine would be sufficient for the burn. Prior to the loading of charcoal, aerator lines were provided for each building, sump and drain so that a forced draft of compressed air could be supplied to intensify the combustion.
Local cooperation
Even though the arsenal is a federal reservation and does not fall in strict terms under the jurisdiction of the city, Lillie felt it prudent to solicit the advice of the City of Philadelphia so that the impact on the local air quality could be minimized. A special exemption was sought since the Philadelphia Air Management Code prohibits open fires for burning materials. However, it did allow for burning when an emergency existed which endangered the public safety and there was no other practical method of disposal.
To ease the concerns of state, city and local community groups of a possible violent explosion, a test burn was conducted last Oct. 3 in two buildings which formerly housed zirconium, sodium carbonate and TNT materials. All groups were invited to the arsenal to observe the burn, which went without incident.
The final burn was scheduled for the following weekend. On Saturday, Oct. 11, all was in readiness for the burn with favorable conditions of weather, wind speed and direction.
While more than 30 of Rockwell’s explosive ordnance personnel were saturating the beds of charcoal, I had already set up a first-aid station, had lines ready to move into the area in case of an accidental fire, and had my entire 16man force on call. Notification was given the fire communications center of the Philadelphia Fire Department that the burn was ready to begin.
Security Chief Harry D. Walters called in his 20-man security team to escort city and local officials, doubled the security of the perimeter fencing against possible trespassing and increased his roving patrol to maintain complete physical security.
Ignition
Ignition of the 400 group buildings took place shortly before 6 p.m. and within minutes the burn was well under way. Sufficient heat had developed 15 minutes later to provide a strong vertical thermal convection which substantially reduced the amount of smoke at ground level. As the intense heat developed, safety personnel reported feeling the ground shake and heard muffled explosions, but no violent explosions occurred. Investigation of the cause of the muffled explosions revealed that a small portion of a wall was blown out in a building which formerly housed primer material and a slab foundation was uplifted by a detonation in the drain line in another building which formerly was used for propellant storage.
The controlled burn was, of course, spectacular, particularly since it took place in a highly populated metropolitan area. Traffic on Interstate 95, immediately north of the arsenal, came to a complete and unplanned stop during the height of the blaze. Thousands of curious sightseers gathered along the fence and over 500 telephone calls were received by the Philadelphia Fire Department, along with numerous fire alarm boxes being transmitted. The Philadelphia Second Alarmers Association provided refreshments to all operational and fire fighting personnel and the news media recorded the event.
By 9 p.m., the burn was completed, although charcoal briquets continued to burn for 10 days.
In view of the magnitude of the thermal decomposition operation which took place and the success incurred without incident, this approach is considered the only practical method for disposal of any explosive materials which might remain as the result of a surplus arsenal’s operations. Some carbon smoke and air pollution will occur as a result of this type of operation, but it will be a relatively minor problem considering the material to be disposed of. When one considers the safety of the people involved in the burn compared to the small amount of air pollution produced in this short period, the choice is clear. □ □