
Hartland 36 Gas Plant Water Quality Update…
A new report on the ongoing investigation and remediation project at the former gas processing plant in Hartland Township is currently under review by the Michigan Department of Environmental Quality (MDEQ). Merit Energy Co. (Merit) is the most recent operator of the site, and they elected to decommission it in 2015.
Upon plant demolition, a previously unknown chemical release of sulfolane was discovered. This discovery resulted in an extensive soil removal project which was conducted to satisfy interim cleanup criteria issued by MDEQ, and to remove the bulk of the source of released sulfolane.
Groundwater investigation activities began in 2015 and were not concluded until Spring 2017. The investigation was completed in multiple phases as Merit’s consultant sought to define the groundwater flow direction, and the vertical and horizontal extent of the sulfolane-impacted groundwater.
The investigation report issued by Environmental Consulting & Technology (ECT) on July 3, 2017 shows that all sulfolane groundwater contamination is still contained within the original five-acre parcel where the former Merit gas sweetening plant operated.
“Off-site migration has been retarded because of an unusual underground geological feature called a “kettle bowl” that includes a tight confining layer of clay which rises in elevation in the southwest direction, which is the direction of the groundwater flow,” said Matthew Germane, senior engineer with Environmental Resources Group and a Hartland Township trustee who is assisting the property owners in a consulting role.
“Since sulfolane is denser than water, the impacted groundwater has settled in the bowl and is restricted from further migration downgradient because the top of the confining layer rises in the downgradient direction — similar to how paint is kept in the lower portion of a painter’s pan so the roller brush can pick it up easier.”
Off-site Drinking Wells Clear
The report also documents the off-site residential well testing program implemented by Merit following a public hearing held at Hartland Township Hall early in 2016. Over 90 private wells, most within a one-mile radius of the former gas processing plant were tested following owner permission. None of the off-site drinking water wells were impacted by sulfolane. The off-site well testing was largely completed before the on-site investigation was completed to calm the fears of nearby residents. Nonetheless, it is supplemental information to confirm and substantiate that the release is still within the original five-acre leased property.
It should be noted that although the groundwater investigation is considered complete enough to allow development of a remediation plan, Merit previously agreed with MDEQ to continue quarterly sampling of all permanent monitoring wells on the property (currently approximately 35 monitoring wells) to document that the contamination plume is stable and not migrating beyond any down-gradient monitoring wells.
Following each quarterly sampling event, a formal report should be completed by ECT and provided to MDEQ, who then eventually shares it with the Livingston County Health Department, Hartland Township and Highland Township.
Testing Bio Clean-up
A pilot test was completed in May and June of 2017 which showed that air sparging is an effective technique to remediate the sulfolane-impacted groundwater. Air sparging is the process of injecting compressed air into the groundwater formation which causes a rise in the dissolved oxygen concentration and thus promotes increased natural biological degradation of the toxic chemical. The biological degradation of sulfolane results in non-hazardous daughter products that can be measured to confirm the remediation technique is successful. According to Merit, a formal pilot test summary report is in progress and, when submitted to MDEQ, should provide a schedule to implement a full-scale remediation system.
So, although Merit had originally suggested testing three different remedial options, the results of the air sparging technology was so effective they opted to not test other options and plan to develop a full-scale remediation system using the results of the pilot test.
Re-greening the Property
The other major effort completed in spring 2017 was to complete final grading, contouring, and topsoil addition so that vegetation could be reestablished on the former five-acre plot.
More information on the Merit Energy Site history is available on the Hartland Township website. ~

