CHARACTERISTICS AND COMMON VULNERABILITIES INFRASTRUCTURE CATEGORY: COMMUNITY WASTEWATER TREATMENT FACILITIES	SENSITIVE HOMELAND SECURITY INFORMATION – LAW ENFORCEMENT SENSITIVE	January 15, 2004	Download
POTENTIAL INDICATORS OF TERRORIST ACTIVITY INFRASTRUCTURE CATEGORY: COMMUNITY WASTEWATER TREATMENT FACILITIES	SENSITIVE HOMELAND SECURITY INFORMATION – LAW ENFORCEMENT SENSITIVE	January 30, 2004	Download

Water System Profile

Wastewater is water that has been used. It includes substances such as human waste, food scraps,
oils, soaps, and chemicals. Wastewater is derived from residential, commercial, and industrial
activities. In homes, wastewater is produced from sinks, showers, bathtubs, toilets, washing
machines, and dishwashers. Commercial and industrial activities also produce wastewater that
must be treated prior to release to the environment. In addition to home and business production,
wastewater can also be generated by storm runoff (referred to as inflow) and interception of
ground water (infiltration). Because of potentially harmful substances that wash off roads,
parking lots, and rooftops, this water must also be treated.

Wastewater is treated in a wastewater treatment facility prior to release. In 2002, the nation’s
wastewater infrastructure consisted of approximately 16,000 publicly owned wastewater
treatment plants; 100,000 major pumping stations; 600,000 miles of sanitary sewers; and another
200,000 miles of storm sewers. About 73% of the population was served by these
16,000 municipal treatment plants; the remainder was served by privately owned systems.
A small number of large wastewater treatment plants (approximately 2,500) located in urban
areas provided services to about 75% of the population. The combined value of the treatment and
collection system was estimated at more than $2 trillion.

The volume of wastewater produced by a community ranges from about 50 to 250 gal per capita
per day (gpcd), depending on sewer uses. A commonly used value for domestic wastewater flow
is 120 gpcd. This water contains about 0.24 lb of suspended solids and 0.2 lb of biochemical
oxygen demand (BOD). BOD is a measure of the strength of a wastewater. It is the quantity of
oxygen used by a mixed population of microorganisms in the aerobic oxidation of the organic
matter in the water. Approximately 99% of municipal wastewater is water.

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CONSEQUENCES OF EVENTS

Two main effects can be produced by attacks on wastewater treatment systems: denial of service,
and hazardous chemical and biological releases. Although contaminants (e.g., Ricin) could be
readily added to the wastewater stream at many locations in the collector system, such attacks
would not produce significant impacts because of subsequent downstream treatment, large
dilution by the receiving body of water, and lack of an immediate user. Denial is a disruption in
the flow of wastewater from residences, businesses, and industries to and through a wastewater
treatment facility. A denial of service can be accomplished by destroying trunk lines, collector
pumps, lift stations, or equipment within the treatment facility itself. Without continued
throughput of wastewater, contaminated water would remain in the system, or be pumped
directly, if possible, to the receiving water without treatment. A buildup of pathogens would
occur, which could lead to an outbreak of public diseases in the area of the collector system.

An attack on a wastewater treatment plant could also lead to the release of contaminated effluent
to the receiving water of the plant. Such releases would primarily affect the environment;
however, there could also be impacts to the general population if the receiving water is used as a
water supply. Because wastewater treatment plants also use and store hazardous chemicals, an
attack could discharge these contaminants to the environment, potentially impacting adjacent
communities. For example, chlorine gas is a widely used disinfectant for secondary treatment of
wastewater, which, if released into the environment, could have lethal effects.
From an attacker’s point of view, a successful attack on a wastewater treatment system can
produce two desirable effects. The first effect is to render the wastewater treatment process
inoperable, thereby creating the potential for disease outbreak, environmental impacts, and a
subsequent loss of revenue. The second effect is to create levels of fear that can result in societal
disruption.

Wastewater treatment systems are vulnerable to three attack mechanisms: physical, electrical,
and cyber penetration. Physical attacks could include destruction of trunk lines, collector pumps,
lift stations, and mechanical components within the treatment facility. An attack on multiple
targets could increase the effectiveness of the attack and lead to much longer down times for the
facility. The direct impact of such attacks would be primarily environmental; however, with a
pathogen buildup, disease outbreaks in the surrounding community are possible. Electrical
attacks could be used to shut down key equipment, such as collector pumps, mixers, aerators, etc.
With such equipment off-line, throughput could be severely restricted and environmental and
health impacts could result. Similar to an electrical disruption, a cyber attack could be used to
control key components of the collector system and the treatment facility. Impacts would be
similar to those produced by an electrical disruption.

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