CONTAINMENT AND DISPOSAL OF AQUEOUS FILM-FORMING FOAM SOLUTION

DEPARTMENT OF THE ARMY

ETL 1110-3-481

U.S. Army Corps of Engineers

CEMP-ET

Washington, D.C. 20314-1000

Technical Letter

No. 1110-3-481

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.

3.

Background.

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.

4.

Guidance.

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