WHITE BEAR TOWNSHIP — A Minneapolis-based environmental consulting and engineering firm reports that soil vapor levels of volatile organic compounds — TCE and t-DCE — on Water Gremlin's property are well below action levels established by the Minnesota Pollution Control Agency (MPCA) and state health department.
Additional monitoring of the volatile compounds will continue.
For now, “preliminary findings of the 2019 remedial investigation, including the recent vapor evaluation, indicate residential homes are not at risk from the on-site release beneath the Water Gremlin building,” wrote Aaron Benker, remediation manager, and Chris Bratsch, project manager for Wenck.
Water Gremlin issued a statement following the Sept. 13 report indicating it initiated a series of tests as soon as t-DCE was discovered below the floor to ensure that vapors do not exist beyond its facilities.
“MPCA reviewed our proposed testing plan and requested additional sampling locations that we added to our plan,” read the statement. “The testing was performed at key locations in the direction of residences closest to our building.”
Test results are provided to the MPCA directly from Pace Analytical, a third-party independent laboratory.
The township facility no longer uses TCE as a degreaser for its battery terminal posts, a toxic solvent Water Gremlin released into the air above permitted levels for 17 or more years. It switched to FluoSolv March 1, an alternative to TCE that contains trans-1,2-dichloroethylene or t-DCE. The product was recommended to Water Gremlin by the Minnesota Technical Assistance Program (MnTAP) back in 2017. After researching TCE replacements at Water Gremlin's request, a MnTAP engineer recommended Fluosolv, noting the Toxic Use Reduction Institute in Massachusetts gave it the “best scores” based on ozone impact, toxicology and performance.
The Water Gremlin release also indicated they have taken action to improve vapor capture inside the building. A system has been installed to capture and direct vapors that might reach the air space below the slab to a carbon filter that captures 100% of the vapors.
“The system addresses historic TCE issues, but also captures any t-DCE from our operations,” noted Water Gremlin. “The systems have been installed and tested, and the results show that they can efficiently and effectively capture TCE and t-DCE, and control t-DCE vapors.”
Wenck was retained by Water Gremlin to conduct the remedial investigation and related follow-up work. Oversight is provided by MPCA. The investigation is also looking at potential contamination to soil, sediment, surface water and groundwater.
As Remediation Manager Benker pointed out, the investigation will establish both the location of impacts at the site and the potential for impacts to migrate to neighboring properties.
On July 30, 2019, Wenck submitted results of its initial remedial investigation to MPCA. As reported earlier by the Press, results of the remedial investigation show TCE impacts are relatively unchanged from the 2004 site data, meaning TCE concentrations had not increased in the past decade.
MPCA now places a greater emphasis on soil vapor migration than it did in 2004, added the Wenck consultants. The agency has developed more stringent vapor mitigation evaluation and action levels that are applicable to the Water Gremlin site.
Volatile organic compounds (VOCs) can migrate by both groundwater and above groundwater in vapor phase between soil particles. VOCs in vapor form can pose a risk to a residence if concentrations are above levels that require action as defined by the MPCA and Minnesota Department of Health.
These action levels are known as intrusion screening values or ISVs.
Coating operations remain on hold
Water Gremlin’s coating operations remain paused as the company continues to work with its customers to transition to a water-based coating solvent that would result in a 50% reduction in t-DCE use and emissions. Read the statement: “While not all our customers are ready to make the switch, we are working hard to confirm its effectiveness and quality to show customers it can meet their specifications.”