PW16 Ecological Risk Assessment (General)
Exhibit Hall
8:00 AM - Wednesday
(PW253) Ecological risk assessment for Lennar Mare Island, a former Naval Station.
Ohlendorf, H.1, Nielsen, K.1, 1 CH2M HILL, Inc., Sacramento, CA, U.S.A.
ABSTRACT- Mare Island was the first naval station established on the Pacific Coast. Shipbuilding operations began in 1854 and continued until 1996 when the naval station was closed. Activities on the island included operations associated with shipbuilding, ship repair, dredge and fill activities, manufacture and storage of munitions, and waste disposal. Portions of the island, including numerous individual sites, are being remediated for redevelopment as industrial, commercial, and residential land uses. Ecological risk assessments (ERAs) are being conducted to determine whether constituents of potential ecological concern (COPECs) in soil, sediment, or water pose risks for plants and animals. The overall goal of the ERAs is to protect the ecological resources on or near the Lennar Mare Island property that may be affected by those COPECs. Because terrestrial habitat and on-site wetlands are very limited, most of the focus is on groundwater that may enter Mare Island Strait adjacent to Mare Island or wetlands adjacent to the property. Analyses of potential groundwater risk to aquatic organisms are based mainly on COPEC concentrations in groundwater monitoring wells adjacent to the Strait or near the wetlands. COPEC concentrations in groundwater are greatly reduced through dilution when groundwater discharges to surface water in the Strait. Ecological risks associated with exposures to groundwater that may discharge to the surface do not take into account possible dilution as the groundwater mixes with surface water in the waterbody during the initial evaluation. If a potential for risk is identified in the initial evaluation, a second evaluation, either quantitative or qualitative, is performed that accounts for possible dilution and other factors. Multiple lines of evidence are used to evaluate the potential risk to aquatic organisms in Mare Island Strait or wetlands, including concentrations of COPECs in groundwater, results of bioassays with sediment or porewater from the Strait or wetlands, dilution factors for groundwater, and other considerations. The overall conclusion is that groundwater discharges pose little or no risk to aquatic organisms.
Key words: coastal ecosystems, ecological risk assessment, groundwater, Navy facilities