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Marengo company now could face fines on top of cleanup costs from December fire
Iowa Department of Natural Resources refers C6-Zero case to the Iowa Attorney General

Jan. 5, 2023 11:55 am, Updated: Jan. 26, 2023 10:57 am
Water flows in a ditch near the C6 Zero biofuel facility in Marengo on Dec. 16, 2022. The ditch leads to a retention pond near the Iowa River. Multiple people were injured in an explosion at the facility that describes itself as a recycler of used asphalt shingles. (Jim Slosiarek/The Gazette)
Part of the C6-Zero facility is reflected on water a day after an explosion and fire at the facility in Marengo on Dec. 9, 2022. Multiple people were injured in an explosion at the facility. (Jim Slosiarek/The Gazette)
Smoke billows from the C6-Zero facility in Marengo on Dec. 8, 2022. Multiple people were injured in an explosion at the facility. (Jim Slosiarek/The Gazette)
The loading dock at the C6-Zero biofuel facility is seen a day after an explosion and fire at the facility in Marengo on Dec. 9, 2022. Multiple people were injured in an explosion at the facility that coverts used roofing shingles into biodiesel. (Jim Slosiarek/The Gazette)
Owners of a Marengo workshop that exploded last month, injuring half its workforce and leaving an environmental mess, now may face thousands of dollars in fines on top of cleanup costs.
The Iowa Department of Natural Resources referred C6-Zero to the Attorney General’s Office for legal action this week after the company said it could not meet deadlines for cleaning up the site.
The DNR ordered C6-Zero to complete an environmental site assessment plan by Dec. 31, but that date passed without a filing. EcoSource, LLC, a Des Moines-area environmental consulting firm, submitted a plan on C6-Zero’s behalf Jan. 3, DNR Spokeswoman Tammie Krausman said.
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“The department is reviewing the information provided, however the dates proposed for clean up do not comply with the Emergency Order,” Krausman said in an email. “Therefore, the department has referred this matter to the Attorney General’s Office for further legal action.”
The Gazette asked the DNR for a copy of the plan, but the agency did not immediately respond.
The DNR has the authority to pursue administrative penalties of up to $10,000, but the Attorney General can seek higher penalties. Iowa law allows for fines of $5,000 a day for water quality violations, $5,000 a day for solid waste violations and $10,000 a day for air quality violations.
“Other factors to consider in making an Attorney General referral recommendation include, but are not limited to, the gravity of the violations, the need for temporary or permanent injunctive relief, presence of multi-media violations, violation of an earlier judicial consent order or judgment, and possible bankruptcy,” the DNR reported in an enforcement management document online.
“The Attorney General does have independent authority to commence civil or criminal proceedings pursuant to section 455B.112 of the Iowa Code.”
C6-Zero describes itself as a recycler of used asphalt shingles, with founder Howard Brand III attempting to use a proprietary solvent to dissolve the shingles into component parts of oil, sand and fiberglass.
The Marengo plant, which opened in 2020 and had about 30 employees, still was in a pilot phase Dec. 8 when liquid solvent in a tank exploded and started a fire. Between 10 and 15 people were treated for injuries at the University of Iowa Hospitals and Clinics and neighbors living near the facility were briefly evacuated.
Since the explosion, DNR staff have noted “multiple large ankle-deep pools” of oily substance and missing walls and ceiling portions suggesting the building isn’t stable, the Dec. 15 order stated. The agency also is concerned about large quantities of chemicals and piles of loose shingles.
Water samples taken from nearby waterways show evidence of pollution from the site, the agency reported.
EcoSource LLC has been working with C6-Zero since the fire to try to determine the best way to clean up the site, EcoSource Owner and Environmental Director Darren Fife told The Gazette Thursday.
“We were involved in the initial response and we have been selected to start taking some of the next steps here,” he said. “We have expertise in dealing with contaminants, contaminant cleanup, the assessment portion and laying out what steps are going to be necessary to move forward.”
Fife said he was aware the DNR referred C6-Zero to the AG.
The plan the company put together for C6-Zero doesn’t meet the state’s deadline of cleaning up the site by later this month. Fife said temperatures at or below freezing make it more challenging to get reliable soil and water samples.
Before starting work, EcoSource is waiting on the DNR’s feedback on the plan and for confirmation C6-Zero or its insurance provider can pay for it, Fife said.
C6-Zero released a statement Thursday saying “cleanup is ongoing.”
“C6-Zero has never indicated that it cannot meet a 45-day deadline and has made no statement in any public or private discussion,” Spokesman Mark Corallo wrote in an email to the Gazette. “While C6-Zero awaits IDNR approval of the Site Assessment Plan, field analytics continue to be gathered to better understand the extent of potential contamination.”
Comments: (319) 339-3157; erin.jordan@thegazette.com