Also included is about 1,100,000 CY of waste rock from the U.S. Corps of Engineers navigation project at Bonneville Locks. This rock was disposed of at the southern end of the Ross Island Lagoon in 1987 and 1988. The preliminary conceptual site model was developed based on the available information about the Port dredged material and the physical and geological characteristics of Ross Island Lagoon. The conceptual site model identifies potential pathways of exposure for contaminants from the disposal of dredged material at the site. The conceptual site model is depicted graphically on Figure 3-1.
Uncertainties remain regarding various components of the conceptual site model.
This information will be used to determine the current and future potential risks associated with exposure to Port-related constituents of concern. Data gaps exist as to the presence of benthic and water column organisms in the deeper and nearshore portions of the Ross Island Lagoon. The tasks presented in this Work Plan are proposed to address these data gaps. An attached simplified version of Table 3-2 presents the proposed exposure pathways, the methods that will be used to measure contaminant concentrations that may exist on those pathways, and the methods that will be used to measure if those concentrations will cause an adverse effect. The first goal of the risk evaluation portion of the Work Plan is to confirm the completeness of the exposure pathways presented on Figure 3-2.