Microbial Activity during Biodegradation and its Effects on Groundwater Velocity in a Contaminated Aquifer

Abstract

A petroleum hydrocarbon plume was introduced into a controlled flow gate within the relatively homogenous Borden aquifer, Canada. Down-gradient of the release, O2 was added to stimulate microbial activity and biodegradation in the aquifer. Changes in groundwater velocity associated with biological activity, were measured with point velocity probes (PVPs) arranged into multilevel standpipes and installed into the flow gate. PVP results were compared with electromagnetic wave velocity measurements from a ground penetrating radar (GPR) survey conducted in the same flow gate. Following the addition of O2, PVP and GPR measured velocities nearest the O2 source changed in a consistent manner throughout the experiment. GPR velocities measured outside the influence of the added O2 did not indicate the same trend. Results from flow modeling combined with gas and biomass measurements, show that PVP and GPR velocity changes were likely caused by factors related to elevated levels biological activity in the aquifer.