Participants

• Judith Pederson, Ph.D. MIT Sea Grant

• Nicholas Gao, M. Eng MIT

• Fenioski Pena-Mora, Ph.D., MIT

• Leo Sommaripa, M.S. MIT

Objectives

• To develop a rigorous, explicit and reproducible approach to improving the understanding and quality of choices for disposal of contaminated marine sediment.

• To use decision analysis to evaluate and balance risk, costs and benefits associated with capping contaminated sediments.

Approach

A trench and cover option has been chosen to manage contaminated dredged material from the BHNIP. Results from the pilot project, dredging of the Conley Terminal berthing areas 11 and 12 and capping in a disposal cell, suggest that the cap is only partially successful. Given the high cost of capping contaminated sediment, the question of balancing the risk of not capping against economic costs is not easily addressed within the current management process. In this regard, decision analysis has several advantages over current practices. It simplifies alternative choices, identifies sets of important factors, forces participants to be explicit in stating biases and assumptions, and defines the decision rule for selecting the best alternative.

Decision analysis models were developed to evaluate the monetary cost of capping under different scenarios as compared to other "costs" such as lost resources to the environment. Data for the basic model was weighted or assigned uncertainty probabilities. The greatest uncertainty will be to evaluate benefits and assign costs to lost resources with no or partial caps. This was treated by assuming nonmonetary values for environmental impacts. The decision model calculated the expected outcomes for each alternative and this "value function"was assessed for utility and robustness. Specific scenarios to be examined are no capping, partial capping (or partially effective capping), and complete capping of cells in Boston Harbor.

In addition, the cost of cleaning the contaminated sediments throughout the harbor were compared over the long term and found to have tje greatest short-term costs but the least cost over the long-term. This model incorporates continues contamination from nearby undredged sediments.

Status Report

Two theses were completed.

Participant Information

• Judith Pederson, Ph.D., is manager of the Center for Coastal Resources at the MIT Sea Grant College Program with interests in marine ecology and the application of science to policy.

• Nicholas Gao completed his Master of Engineering with the MIT Civil and Environmental Engineering Department and has entered law school.

• Fenioski Pena-Mora, Ph.D., is an Assistant Professor with the Civil and Environmental Engineering Department at MIT.

• Leo Sommaripa completed his Masters in Civil and Environmental Engineering.