Microbes – Part 3

It's been one month since our microbial inoculation, and we've made remarkable progress.

Initially, six monitoring wells contained measurable free-phase gasoline, but now only two remain! The petroleum hydrocarbons floating on the groundwater within the monitoring wells provided an excellent food source for microbes to consume.

Now, the big question: are these microbes continuing to eat and migrate beyond the

monitoring wells?

Monitoring well construction is regulated by the Oklahoma Water Resources Board (OAC785:35-7-2). For environmental wells, boreholes are typically created using 6.25” or 8.25”augers. The completed well is comprised of a PVC casing, generally a 2” or 4”diameter pipe, with slotted sections that allow aquifer groundwater to flow through. A minimum 3” annular space between the casing and the wellbore is filled with a filter pack of quartz sand or silica.

This filter pack is followed by layers of hydrated sodium bentonite pellets and a cement or

bentonite grout seal. Finally, a concrete surface seal is poured.

It's likely our microbial allies have digested the petroleum hydrocarbons within the wellbore

and moved into the filter pack, seeking surfaces to attach to. However, we aim to encourage

their migration beyond the ~2’ wellbore radius. One option would be a costly vacuum

extraction event, which would generate significant groundwater requiring disposal.

Alternatively, we propose a more efficient solution: a freshwater flush containing blue tracer

dye following the inoculation. This strategy would propel the microbes deeper into the

formation, allowing them to discover new hydrocarbon food sources. This time, we'll track their progress linearly.