A Field Scale Study of Serial Treatment using Slurping and in situ Soil Flushing to Remediate an Oil Contaminated Site

Abstract

A combined treatment of bio-slurping, to extract soil vapour and withdraw free-phase oil and in situ soil flushing, to remove residual pollutants distributed in the saturated zone, was performed for 9 months and 1 month, respectively, to remediate an oil contaminated site that covered an area of 1,500 m². Twenty-eight extraction wells were used for the operations and average monthly amounts of soil vapour extraction were 385,000 m³. The removal efficiency for total petroleum hydrocarbons (TPH) and BTEX compounds (benzene, toluene, ethylbenzene, xylene) was 59.5 and 79.8 %, respectively, and was achieved after applying the two processes over a 10-month operational period. The spread of free-phase oil contamination followed the direction of ground water flow in this area. Removal of oil was less successful at higher ground depths. Concentrations of TPH and BTEX decreased by 64.1 and 87.1 %, respec-tively, at a subsurface depth between 6 and 7 m following the application of these two processes.