Uncertainties Associated with the Preliminary Ecological Risk Assessment Process: Case Study

A preliminary (i.e., initial tier) ecological risk assessment (ERA) was conducted, as part of the RCRA Corrective Action Process at Launch Complex 37 at the Cape Canaveral Air Station (CCAS) to evaluate whether potential hazardous constituent releases could result in adverse effects to ecological resources. An uncertainty analysis was conducted as part of the ERA to assess the degree of conservatism associated with the estimated ecological hazard quotients (HQs). U.S. Environmental Protection Agency protocol was used to calculate the HQs for four terrestrial receptor species (Florida mouse, southeastern American kestrel, Florida scrub jay, and mourning dove) that could be exposed to 14 organic compounds and 8 metals identified as chemicals of potential concem (COPCs) in on-site soil. Site soil concentrations, toxicity reference values (TRVs) from the literature, and conservative assumed uptake and exposure factors were used for the HQ calculations. The uncertainty analysis included back-calculating risk-based soil screening concentrations (RBCs) from the HQs for those receptor species and corresponding COPCs for which the HQs exceeded 1. Some of the RBCs were below conservative generic soil screening criteria and below or on the order of local background levels. The uncertainty analysis indicated the high degree of uncertainty and conservative nature of the ERA results.