DEPARTMENT OF THE ARMY
U.S. Army Corps of Engineers
Washington, D.C. 20314-1000
31 March 1997
Engineering and Design
CONTAINMENT AND DISPOSAL OF
AQUEOUS FILM-FORMING FOAM SOLUTION
1. Purpose. This letter provides design guidance for
containment and disposal of aqueous film-forming foam (AFFF)
discharges from AFFF fire extinguishing systems.
2. Applicability. This letter applies to all HQUSACE elements
and USACE commands having military construction and design
responsibility. This ETL has been coordinated with the Air Force.
a. AFFF fire suppression systems are typically provided in
aircraft hangars. AFFF systems have superior fire extinguishing
capability and can effectively control a flammable or combustible
liquid fire. This type of protection is necessary to protect
valuable, mission-essential aircraft and hangar facilities.
b. A concern of AFFF systems is the discharge of AFFF foam
solution. In large volumes, AFFF foam can be harmful to the
environment. AFFF solution should not be allowed to flow
untreated into the ecosystem, or into the sewage systems in large
quantities. The primary concern is discharge from unwanted
activations and from periodic testing.
c. Except for this technical letter, there is little
information on this subject and no specific design guidance that
provide a reasonable approach to handling AFFF discharges.
a. Containment systems will be provided for all fixed AFFF
fire extinguishing systems. Containment systems will be designed
to contain the most probable worst case AFFF discharge. The most
probable worse case AFFF discharge is defined as the maximum
discharge likely to occur in a non-catastrophic event. The most
probable worst case is different for open fire extinguishing
systems and for closed fire extinguishing systems.
b. AFFF discharges associated
with major fires are not
considered the most probable worst
case for two reasons. First,
a major fire would be considered a
catastrophic event. Second,
an occurrence of a major fire in a
well protected hangar is not