What is the format of a risk assessment?

Technical Note DOER-R1

September 1998

primary, although not exclusive, considerations when evaluating disposal alternatives are

effectiveness, implementability, and cost. The dredged material manager should ask the following

risk-based questions (USEPA 1991) in evaluating disposal alternatives:

Which alternatives can readily achieve acceptable risk levels in sediment and biota? What

uncertainties are involved in this determination?

Which alternatives will clearly not address the primary exposure pathways identified in the

risk assessment?

Are the expected residual risks or short-term risks from one alternative significantly different

from another?

What other risk-based benefits (e.g., shorter time to achieving goals) are realized by selecting

one alternative over another?

Will implementation of specific alternatives create new, significant exposures or risks to

human or ecological populations?

Is there a need for engineering controls or other measures to mitigate risks during implemen-

tation, and are these controls available and reliable?

Will any of the alternatives present additional risks to threatened populations or communities

[minority communities (Executive Order 12898, February 11, 1994, "Federal Actions to

Address Environmental Justice in Minority Populations and Low-Income Populations"),

Native American subsistence fishermen, living resources, endangered species]?

There are four general categories of alternatives:

No-Action and Port Operation Alternatives. In its most elemental sense, the no-action

alternative means that the proposed dredging project is rejected, and the contaminated

sediments remain in place. This usually leads to one or more "port operation alternatives"

such as channel rerouting and lightering.

Engineering Alternatives: Dredging. Dredging and the discharge of sediments at a disposal

site are the predominant methods for constructing and maintaining ports, channels, and

berthing areas. The dredged material manager should clearly describe his/her selected

alternative, including the performance and limitations of the equipment.

Engineering Alternatives: Confined Disposal. Confined disposal can apply at upland or

aquatic sites. The Framework Document includes a detailed review of confined disposal

alternatives used in the United States, and provides references of more detailed information

sources on the subject.

Other Engineering Alternatives. Other engineering alternatives include upland disposal,

incineration, separation technologies, and other treatments. Cullinane et al. (1986) and

USEPA (1993) provide detailed descriptions of such alternatives, and possibilities for their

future applications.

What is the format of a risk assessment? There are numerous program-specific documents

that describe the formal components of a risk assessment and detail how to conduct one within the

constraints of the program. USACE is preparing a detailed technical guidance document for

operations personnel. The dredged material manager should recognize that risk assessments include