In situ bioventing at a natural gas dehydrator site: Field demonstration

This paper describes a bioventing/biosparging field demonstration that was conducted over a 10-month period at a former glycol dehydrator site located near Traverse City, Michigan. The goal of the project was to determine the feasibility of this technology for dehydrator site remediation and to develop engineering design concepts for applying bioventing/biosparging at similar sites. The chemicals of interest are benzene, toluene, ethylbenzene, and xylenes (BTEX) and alkanes. Soil sampling indicated that the capillary fringe and saturated zones were heavily contaminated, but that the unsaturated zone was relatively free of the contaminants. A pump-and-treat system has operated since 1991 to treat the groundwater BTEX plume. Bioventing/biosparging was installed in September 1993 to treat the contaminant source area. Three different air sparging operating modes were tested to determine an optimal process configuration for site remediation. These operational modes were compared through in situ respirometry studies. Respirometry measurements were used to estimate biodegradation rates. Dissolved oxygen and carbon dioxide were monitored in the groundwater.