Former Gas Station

Project Summary

A former gasoline service station located in Madison, NJ was impacted by petroleum hydrocarbons as a result of releases from former underground storage tanks (USTs). Excavation of the USTs, associated piping, and shallow hydrocarbon soil impacts had previously been completed; however, excavation was limited due to accessibility constraints from the service center building and road.

Following excavation and enhanced fluid recovery, residual benzene, toluene, ethylbenzene, xylene (BTEX), trimethylbenzene (TMB), and light non-aqueous phase liquid (LNAPL) impacts remained. The geology, which primarily consists of dense silt and clay with groundwater at 30 feet below ground surface (ft bgs), presented an injection challenge.

Provect-OX® was selected to address the residual sorbed and dissolved phase petroleum hydrocarbon contaminant mass, including LNAPL.

Remedial Plan

ISCO plus enhanced bioremediation application of 13,300 lbs of Provect-OX® applied via 20 temporary direct push injection points. The service center remained open and active during drilling and injection activities.

Results

• Oxidative conditions observed from increased ORPs (+33 to +354 mV)
• Targeted monitoring wells reported 88-99% VOC reductions.
• LNAPL was eliminated.
• Transition to reducing conditions confirmed, supporting ongoing iron and sulfate enhanced bioremediation.
• Additional contaminant concentration decreases anticipated as secondary bioremediation processes continue.