DECIDING WHEN TO INTERVENE

Brief summary of breakout group A

Breakout Group A was facilitated by Gail Krantzberg (MOE) and John Hartig (IJC).

Breakout Group A defined and discussed the critical data elements that should be considered within a framework, addressed the various decision-making tools, examined the role of these decision-making tools in the restoration of beneficial uses, and proposed an "Integrated Framework" for sediment management decisions.

The goal for each of the Breakout Groups was to provide advice on use of data interpretation tools used to make sediment management decisions.

Data elements and conceptual decision-making rules

The first point to be addressed was the problem with decision-making rules in regard to the exact point where we see enough scientific evidence to say "take action". Although there may be similar data at two sites, decisions to act may be for entirely different reasons. So the question was posed: Do we use the same decision-making method at every site, or should the method be more site-specific? There was an agreement throughout the Group that there should be consistent data interpretation rules and protocols applied to all Areas of Concern.

Then the following question was asked: Does a certain result of a protocol lead to the decision to act or not act? A result of a protocol doesn't necessarily determine the action, a combination of tests do. Additional knowledge is necessary. For example, in regard to research needs, ecologically defined points of departure from reference conditions needs to be defined using the direction of the trajectory with respect to distance from the reference condition and with respect to time.

Ways of interpreting data became the next focus. It was stated that when human health is the issue, the decisions tend to be more standard-driven, whereas when the benthic community is the issue, the decisions tend to be more reference-driven. Human health standards might override the benthic community data. Other ways to evaluate the benthic community besides the reference approach include bioassessment, abundance, and diversity. There is no one single way to interpret the data and apply it to all sites.

The next point made was that reference conditions can be used to interpret benthic community and toxicity test data. There is a need for multiple reference sites. The scales will be different when you test at different sites. Selecting reference sites requires examination of the species at hand. A reference site data base needs selection of common protocols. For site-specific conditions, there is a need for an historical control reference site. However, how do you pick the control site, and if in the lab you pass the first site specific control, is there a need to continue?

In regard to the benthic community, bioaccumulation and biomagnification were discussed. In terms of causality, bioaccumulation can be used to interpret observed toxicity, exposure duration, pathways, tumors and deformities, and degree of uptake. In terms of bioaccumulation and biomagnification, we need site specificity for determining remediation. We need to measure changes in the function of the benthos vs. structure.

Bioaccumulation and biomagnification were also discussed as important routes of exposure by which contaminants in the sediment can reach fish and fish-eating birds and mammals, including humans. Contaminants like PCBs can be present at concentrations in sediment which are not toxic to benthic invertebrates, yet can result in fish consumption advisories for humans and impaired reproduction in fish-eating wildlife like mink and bald eagles.

The stability of the area of contaminated sediment was also discussed as a possible criterion by which remediation extent and urgency might be evaluated. A decision might be made to remediate an area despite there being no current toxicity to benthic invertebrates in the laboratory, no change in community structure from reference areas, and no evidence of current exposure to higher trophic levels. For example, a subsurface deposit of contaminants may be at high risk of physical disturbance, which would be expected to result in a change in bioavailability and an increase in the difficulty and expense of later remediation.

As a result of the points made thus far, the following elements were chosen to be critical in carrying out a proposed Framework: benthos community structure, laboratory toxicity, bioaccumulation and biomagnification, stability, and sediment chemistry. Bioaccumulation and biomagnification includes estimates of tissue concentrations in both invertebrates and vertebrates in the rest of the food web. Stability includes fate and transport, the potential for mobility with disturbance over long time periods, and the bioavailability over a range of sediment, sediment porewater, organismal micro-environment and over-lying water chemistry (e.g., pH, redox, hardness).

The next point made was the difficulty in quantifying the relationship between contaminated sediment and beneficial uses. We need to begin by examining use impairments and their link to sediment quality. The following screen was outlined to determine if and when remediation is necessary. You must examine the following:

• Benthic Community
• Lab Toxicity
• Bioaccumulation/Biomagnification
• Stability
• Chemistry

You cannot base a "no action" decision on any one element solely. Generally, you base a decision on the integration of these five elements through interpreting data sets and attempting to determine causality and linkages to beneficial uses.

Proposed Framework

Review Impaired Uses
Perform preliminary screening of linkages between contaminated sediment and use impairments: -- Benthic communities -- Lab Toxicity -- Bioaccumulation/Biomagnification -- Stability -- Chemistry
No major problem if first four are alright	Problem if any are substandard
Continue with routine monitoring	Perform intensive assessment of quantitative relationships between contaminated sediment and use impairments. Then integrate data sets to make decision "to act" or "take no further action"