Dredging: Contaminated Sediments

U.S. Army Corps of Engineers Research Report Summary, December 1998

Dredging Operations and Environmental Research Program

Dredging:

Contaminated Sediments

Improving Dredged Material Management Decisions with Uncertainty

Analysis (TR DOER-3)

ISSUE: Federal laws and regulations require

q Making preliminary recommendations for

the U.S. Army Corps of Engineers (USACE)

further refinement of the ranking.

and U.S. Environmental Protection Agency

SUMMARY: The most significant sources of

(USEPA) to assess the potential for dredged

uncertainty within the tiered evaluation process

material management activities to have signifi-

included identification of the contaminants of

cant undesirable effects on human health or the

concern, the selection and use of reference sedi-

environment. The USACE and USEPA have

ments, trophic transfer of sediment-associated

developed an evaluation process for making

contaminants, the potential for chronic toxicity

dredged material management decisions to pro-

and the use of chronic sublethal bioassays, defi-

tect against such effects. Uncertainty regarding

nition of assessment and measurement end

the ecological and human health risks associated

points during the conduct of an environmental

with dredged material disposal alternatives can

risk assessment, the use of contaminant fate and

lead to delayed, costly, and unwise decisions.

transport models, tissue-based measures of tox-

Uncertainty about the likelihood for unaccept-

icity, dose-response models for human recep-

able impacts can result from the lack of knowl-

tors, and the toxicity of complex mixtures.

edge about critical elements or processes

Specific recommendations for the need for more

contributing to risk or natural variability in the

extensive field validation for many of the com-

same elements or processes.

ponents in the tiered evaluation process were

RESEARCH: The objective was to discuss the

made.

importance of uncertainty in environmental de-

AVAILABILITY OF REPORT: The report is

cision making through specific reference to the

available in .pdf format on the World Wide Web

dredging program. The approach taken in-

at http://www.wes.army.mil/el/dots and through

cluded the following steps:

Interlibrary Loan Service from the U.S. Army

q Describing in detail the uncertainty sources

Engineer Waterways Experiment Station

within the tiered evaluation process.

(WES) Library, telephone (601) 634-2355. To

purchase a copy of the report, call NTIS at (703)

q Ranking sources of uncertainty within the

487-4780.

tiered evaluation process by degree of

contribution.

About the Authors: Dr. Todd S. Bridges performs research at WES; contract support was

provided by Drs. Donna J. Vorhees and Susan B. Kane Driscoll and Ms. Katherine von Stackel-

berg, Menzie-Cura and Associates, Inc., Chelmsford, MA. Point of Contact: Dr. Todd S.

Bridges, Principal Investigator, telephone (601) 634-3626, or e-mail

bridget@mail.wes.army.mil.

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