Oil residue on water

Environmental Liability Management for Leaking Underground Oil System


Antea Group’s client was responsible for maintaining an underground fuel oil distribution system for a residential community in the northeastern part of the United States. In 1987, the client observed unexplained fuel oil losses. Investigation revealed a lack of cathodic protection between feed lines and the main fuel oil distribution line. This resulted in conduit corrosion, which led to oil leaks to the subsurface soil and surface water at over twenty locations. The corrosion and oil leaks were located within a former cranberry bog and its tidally-influenced geologic setting. 

The strategy to address these releases involved:

  • Repair of leaking lines
  • Installation of cathodic protection 
  • Removal of oily soils under homes
  • Installation of vapor barriers under homes
  • Installation of sub-slab depressurization systems in affected homes
  • Installation of booms in water bodies to contain sheens

As mandated by the state’s Department of Environmental Protection (DEP) in 1988 under an Administrative Consent Order (ACO), Antea Group’s client was required to investigate the extent of fuel oil loss, evaluate risks to residents, and to recover oil. This would meet state DEP standards of maintaining human health, public welfare, and environmental protection. 


To satisfy the project scope, Antea Group performed the following activities:

  • Installed soil borings and monitoring wells and developed a site conceptual model
  • Completed a Remedial Investigation/Feasibility Study (RI/FS)  
  • Installed 14 dual pump underground recovery systems
  • Performed boom maintenance
  • Completed performance groundwater monitoring and NAPL (Non-Aqueous Phase Liquid) gauging
  • Handled DEP permitting
  • Managed DEP monitoring and reporting
  • Completed semi-annual DEP ACO reporting
  • Completed recovery well redevelopment
  • Prepared recovery system Operations and Maintenance (O&M)
  • Demonstrated asymptotic conditions to support recovery system, decommissioning and discontinuing all but one DES (National Pollutant Discharge Elimination System) permitted outfall
  • Developed a multipoint three-phase (LNAPL (Light Non-Aqueous Phase Liquid), vapor and water) portable recovery system for continuing occasional LNAPL recovery during low tide


Antea Group’s efforts in removing recoverable LNAPL and implementing corrective action helped to mitigate risks to affected homes. Antea Group enabled the client to close an expensive dual pump recovery system at a cost savings of $150,000 per year. Finally, Antea Group won a state award for its innovative multipoint three-phase portable recovery system.