Remediation of Petrol and Diesel in Subsurface from Petrol Station Leaks

Abstract:

Leaks from piping and underground storage tanks at petrol (gasoline) and diesel service stations, as well as surface spills that permeate the forecourt, can lead to contamination of soil, ground water, and the soil gas phase, and remediation often involves treating all of them. While small leaks may contaminate very local soil, larger ones can lead to nonaqueous phase liquids (NAPL) floating on ground water. Vapors from such plumes contaminate the vadose zone above the water table, and soluble components dissolved in the ground water and NAPL may migrate off site. Remediation activities should consider treatment requirements for all the three phases, and typically will initially rely on mechanical means. Simple excavation and removal of contaminated soil with treatment off-site are the most prevalent treatment, although in situ techniques are often preferred, especially when contamination extends under structures. In situ methods include physical pumping of the NAPL floating on the water phase and vacuum extraction to remove volatile hydrocarbons from the water and soil, and in situ chemical oxidation of the contaminant. In situ bioremediation is sometimes the primary treatment, and often plays a “polishing” role in removing residual material underground. Biodegradation can also play a role in treating extracted air and water.