KeySpan Bay Shore
Manufactured Gas Plant (MGP)
Bay Shore, New York
Paulus, Sokolowski and Sartor (PS&S) implemented a $1.1 million Interim Remedial Measure (IRM) to remediate impacted groundwater. The IRM included three phases: excavation and disposal of impacted soil; in-situ chemical oxidation; and enhanced biodegradation. The excavation portion of the IRM was designed to remediate three defined “hot spots” that contained elevated concentrations of MGP-related constituents. Excavation depths ranged from eight to twelve feet below ground surface (bgs) and two to four feet below the water table. Steel sheeting was driven to depths ranging from 30 to 40 feet bgs to shore the excavation and to minimize groundwater intrusion. Approximately 1,500 tons of soil was excavated within a temporary enclosure. The temporary enclosure maintained the excavation area under negative air pressure and prevented air emissions from migrating beyond the immediate work zone. Level B Personal Protective Equipment (PPE) was utilized during work within the temporary enclosure.
After completion of the excavation phase, stabilized hydrogen peroxide was injected into the subsurface soils between the “hot spot” areas to oxidize residual contaminants. The injections were performed at 27 discrete locations across the site. Finally, an oxygen injection system was installed to enhance biodegradation of dissolved phased organic chemical constituents in groundwater. The oxygen injection included the installation of 35 microwells connected to an on-site oxygen generator which continuously pulses oxygen into the groundwater.