Terminal Avenue Brownfield
The Brownfields redevelopment project at 721 Terminal Avenue began with conducting a Phase I environmental site assessment (ESA) and a wetland delineation for a buyer considering the undeveloped 2-acre property in Wilmington, Delaware. Based on the findings, a Phase II ESA was conducted. The buyer entered the property in the DNREC State Brownfields Development Program based on the results of the Phases I ESA and Phase II ESA reports with the intent of developing the property for future commercial use while getting liability protection and financial assistance through the Brownfields Program.
Landmark collected soil samples, sediment samples, groundwater samples, and surface water samples at the Terminal Avenue brownfields redevelopment site, which were analyzed by a DNREC-sanctioned laboratory and found to contain high concentrations of heavy metals and semi-volatile organic compounds. The analytical results, cleanup recommendations, and risk assessment data were issued in a Brownfields Investigation (BFI) report. The data in the BFI report along with the wetland functional assessment and the clean-up actions described in the Final Plan of Remedial Action issued by DNREC were used to design an acceptable Remedial Action Work Plan.
Due to the elevated risk to human health from the on-site contaminants, a 12-inch thick (minimum) earthen cap was designed to be placed over the entire subject property to permanently encapsulate and prevent future exposure to the underlying contaminated soils and sediments. Placement of the proposed cap over the entire site necessitated the construction of a structural retaining wall, piping an existing drainage ditch, and filling an existing non-tidal emergent wetland with clean imported fill material, which required a Nationwide Permit (NWP) 38 from the U.S. Army Corps of Engineers (USACE) and a Subaqueous Lands permit from Delaware DNREC Wetlands Section. The USACE issued a NWP 38 for the permanent filling of 1.2 acres of wetlands and Waters of the U.S. (WOTUS).
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