Deep Air Sparging—15 to 46 m beneath the Water Table

Abstract

AbstractAir sparging can be successfully applied to deep aquifers to remediate significant hydrocarbon mass in order to ultimately reach a point at which monitored natural attenuation can manage dissolved phase plumes. Air sparging is typically applied in shallow ground water conditions, less than 15 m beneath the water table (bwt). Deep air sparging, 15 to 46 m bwt, is more challenging but a viable alternative for treatment of residual petroleum hydrocarbons and dissolved phase constituents within a thick smear zone. An application to remediate an aquifer impacted by gasoline‐range petroleum hydrocarbons at depths greater than 76 m below ground surface (bgs) and up to 40 m thick (vertically) is reported here. Deep air sparging at 15, 31, and 46 m bwt was assessed using diagnostic tools involving flow rate, pressure, tracer gas, water table elevation, vapor concentration, and ground water chemistry measurements. The diagnostic tools identified preferential flow directions and a maximum depth of effective air injection. The full‐scale deep air sparging/soil vapor extraction (SVE) system removed more than 150,000 kg of hydrocarbon mass at the study site over a 3‐year period and ultimately greater than 100,000 kg/year with system expansion.