South Wilmington Wetland Preliminary Remediation Goals (PRGs)


Location: Wilmington, Delaware

Overview:

  • Develop ecologically-based Preliminary Remediation Goals (PRGs)
  • Projected post restoration conditions
  • Food chain modeling
  • Equilibrium pore water estimation and comparisons to narcotic and non-narcotic benchmarks
  • Passive sediment sampling procedures
  • Site-specific benthic toxicity evaluations
  • Metals speciation using Synchroton XRF techniques
South Wilmington Avatar Environmental Project

Description:

Avatar was tasked to develop ecologically-based Preliminary Remediation Goals (PRGs) for a 22-acre wetland area in Wilmington, Delaware. The South Wilmington Wetland (SWW) area floods regularly during major storm resulting in flood damage to hundreds of residents in the surrounding low income neighborhoods. The city of Wilmington is looking to clean-up and restore this area in an effort to prevent future flooding and to provide safe and attractive wetland habitats that can be enjoyed by nature enthusiasts as part of an extensive waterfront park complex.

Historical hazardous waste dumping activities have left large portions of the SWW area contaminated with heavy metals, SVOC s and PCBs. Avatar incorporated existing habitat information and projected post restoration conditions with contaminant distribution profiles to estimate potential future exposure levels for a variety of anticipated ecological communities. Several ecological risk assessment techniques including food chain modeling, equilibrium pore water estimation and comparisons to narcotic and non-narcotic benchmarks were incorporated to assess ecological risks to restored habitats. PRGs for contaminants that exceeded toxicity screening levels were calculated using a variety of back-calculation procedures.

The initial PRGs were used to identify levels of Contaminants of Concern (COCs) that could result in adverse ecological impacts. Subsequently PRGs were refined using a combination of recently developed passive sediment sampling procedures, site-specific benthic toxicity evaluations and metals speciation using Synchroton XRF techniques. These additional assessment procedures were done in conjunction with the University of Maryland and the University of Delaware. South Wilmington Avatar Environmental Project