Client: Greater New Orleans Expressway Commission
Completion Date: Ongoing
Employees at the Greater New Orleans Expressway Commission (GNOEC) reported a diesel fuel odor in the storm drain system at the Lake Pontchartrain Causeway South Shore Toll Plaza. GEC environmental personnel inspected the site and determined that the source of the fuel centered around the former site of a 500-gallon diesel UST.
GNOEC immediately authorized emergency abatement activities and three recovery wells were installed at the site. Subsequent subsurface site investigations revealed free-phase diesel fuel in groundwater contained within the sheet-pile wall surrounding the site. The unique physical structure of the site as well as the placement of several administration buildings within the confines of a hurricane protection levee made traditional remedial options impractical. A Dual Phase Vacuum Extraction (DPVE) unit was selected to remediate the subsurface plume. Due to the proximity to Lake Pontchartrain and the subsequent groundwater level fluctuations caused by lake levels, the DPVE system piping within the wells required constant adjustment to ensure optimum product recovery.
After several months of operation, the DPVE system successfully recovered all traces of the free-phase product. After the installation of additional soil borings and groundwater wells, GEC evaluated the data, and completed a site-specific Risk Evaluation Corrective Action Program (RECAP) evaluation recommending closure strategies for the site. The RECAP documents are currently undergoing review at LDEQ.