Environmental Engineering Reference
In-Depth Information
Vulnerability Analysis
The vulnerability analysis, sometimes called a conse-
quence analysis, involves determination of the areas, populations, and facilities
that may be at risk if a release occurs. A list summarizing those critical facilities
in the county or municipal area whose loss would severely hamper emergency
operations or increase the potential for loss of life or property should be included
in the plan.
Risk Analysis
The purpose of the risk analysis task is to determine the potential
and severity of a possible incident. Methodologies are available for calculat-
ing estimates of the quantity of a release, the rate of dispersion, and possible
concentrations that could affect human health. The previously identified EPA
document
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lists a number of publications and computer programs available
from federal agencies, such as the
Handbook of Chemical Hazards Analysis Pro-
cedure
(“Brown Book”), which provide fairly detailed information useful for
estimating the size of zones considered vulnerable to toxic effects from accidental
releases. These documents give additional information on suggested levels of con-
cern. When completed, a local risk and vulnerability analysis should provide the
following:
Geographic description of the areas deemed vulnerable to the identified
hazard
•
Size and type of populations expected to be in the defined vulnerable zones
•
Property and essential utilities services that may be affected
•
Environmental media that may be affected
•
Examples of emergency planning information that result from this process
include needs for facilities and equipment; identification of safe zones for
conducting response coordination and the type of equipment needed for event
mitigation, emergency worker protection, and spill clean-up. Also, criteria for
determining the extent of emergency response required can be established.
Additional information that should be included in the risk analysis is identifica-
tion of important community resources. Sources of water are particularly vulner-
able to environmental emergencies. Groundwater supply wells or surface-water
reservoirs should be located on maps. Water supply distribution systems, impor-
tant transportation routes, electrical supply substations, and wastewater treatment
plants are examples of community resources that should be factored into risk
analysis. Recently, geographic information systems (GISs) — computer systems
capable of assembling, storing, manipulating, and displaying geographically refer-
enced information — have become widely used to electronically map community
resources, thus enabling risk planners who must respond to emergency situations
to have access to relevant data identified according to their geographic loca-
tions, such as population densities, wetlands, groundwater resources, or critical
conservation areas.
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Emergency action levels (EALs) or an incident classification system should
be included in the planning process because they are preestablished conditions
