ENV-06-160 Sediment Remedial Approach - Monitored Natural Recovery

Description:

Under the Resource Conservation and Recovery Act (RCRA) Corrective Action program, sediments were investigated from a small urban stream located on the property of a former Midwestern refinery. The sediment samples collected and analyzed from the stream were found to have elevated levels of polyaromatic hydrocarbons (PAH). Seeps of light non-aqueous phase liquid (LNAPL) to the stream from the adjacent bank soils were determined to be one possible contributor to the elevated PAH concentrations. As part of the Corrective Action Process, human health and ecological risk assessments were completed for the creek sediments. The human health risk assessment evaluated potential adult/child trespasser and industrial worker exposure scenarios, and the ecological risk assessment evaluated ecological receptors within the creek. The results of the human health risk assessment indicated no unacceptable risk to human health. However, a potential risk to benthic invertebrates (e.g., worms) was identified in the ecological risk assessment due to PAH contaminants present in sediment at specific sample locations. Based on this potential risk, the United States Environmental Protection Agency (USEPA) required the site to develop and submit a Corrective Action Study to evaluate remedial alternatives that address the PAH concentrations in the sediments.