Developing Testable Hypotheses

operation. This fact provides a logical basis for establishing an appropriate

tiered monitoring program that emphasizes physical monitoring in the

lower tiers.

Physical processes of interest include the spreading and mounding

behavior of the contaminated and capping layers during disposal

operations, the potential erosion of these deposits due to currents and wave

action, and the consolidation of the deposits and underlying sediment

layers. Erosion and consolidation processes dictate the long-term

thickness of the cap. The components of a monitoring plan needed to

address these processes include periodic precision bathymetry, perhaps

supplemented with SPC surveys, settlement plates, or other

Chemical processes of interest include potential mixing of contami-

nated material with the clean capping material during the construction

phase, and perhaps in the long term due to bioturbation, and the potential

migration of contaminants upward through the cap due to advection or

diffusion. The components of the monitoring plan addressing these

processes include sediment cores for chemical analysis of sediment or

interstitial water to define the chemical profile of the contaminated and

clean capping layers. Additional cores taken over time at the same

stations would detect any upward migration of contaminants.

Biological processes of interest include type/quantity of organisms

present and the potential for contaminant effects (i.e., toxicity and/or

bioaccumulation) should contaminant migration occur or should the

integrity of the cap be compromised. Components of monitoring that

address these processes include sampling and analysis of benthic

organisms that would colonize the site following completion of capping.

Developing Testable Hypotheses

Testable hypotheses must be established that are tied to critical

threshold levels that, when exceeded, trigger a higher monitoring tier or

implementation of a management action. Development of reasonable and

testable hypotheses requires a prediction of the end result of the various

processes that may occur at the site. A null hypothesis is developed (i.e.,

that there is no significant difference between predicted and observed

conditions); if the threshold is exceeded, the null hypothesis is rejected.

Tiers must be structured so that early warning of potential problems can

be detected. Often physical monitoring may be the best tool in the lowest

tier, but biological or chemical tools may have appropriate roles in the

lowest tier as well. The key is to get relatively rapid, inexpensive, and

interpretable results.

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Chapter 9 Monitoring Considerations for Capping