Terraphase performed an ecological risk assessment (ERA) to support a brownfield investigation and feasibility study for the revitalization of a historically impacted wetland area in Delaware. The developer’s vision is to transform the site into a restored habitat that delivers ecological and community benefits.

Scope of Services

Using state, regional, and federal guidelines, the ERA evaluated potential risks to terrestrial plants and invertebrates, rooted aquatic plants, benthic invertebrates, fish, birds, and mammals. Exposure was estimated to contaminants in soil, sediment, and surface water. Of the dozens of chemicals analyzed, only 10 were identified as chemicals of potential ecological concern (COPECs).

Following the initial screening, a baseline ecological risk assessment (BERA) evaluated the COPECs more comprehensively using receptor-specific thresholds and food chain modeling.

American robin, short-tailed shrew, muskrat, spotted sandpiper, great blue heron, and largemouth bass were selected as receptors representing different feeding guilds (e.g., herbivores, invertivores, omnivores) and exposure media. Metals were identified as the primary risk drivers (i.e., chemicals of ecological concern [COEC])for all receptors, except the short-tailed shrew for which high molecular weight polycyclic aromatic hydrocarbons (PAHs) were also identified.

Using the results of the BERA, risk-based preliminary remediation goals (PRGs) were developed to support remedial planning and designs. Regional background concentrations for metals were also taken into consideration when selecting the PRGs.

Following review by the Delaware Department of Natural Resources and Environmental Control (DNREC), the outcome of the BERA and the resulting PRGs will be used in a feasibility study for focused remediation and redevelopment of the site into a community asset.

Notable Accomplishments

• ERA was conducted per state, regional, and federal guidance for multiple ecological receptors
• Contaminant exposure assessed in soil, sediment, and surface water
• Ten COPECs were identified from dozens of chemicals analyzed
• BERA was completed using receptor-specific thresholds and food chain modeling
• Metals were identified as primary COECs
• Risk-based PRGs were developed to support remedial planning
• BERA and PRGs to inform feasibility study for focused remediation, and community-focused site redevelopment, following DNREC review