Cleanup of Marengo blast site to take until March, consultant says

Diesel that washed from a Marengo plant after an explosion and fire has been found in a drainage ditch and retention pond at levels eight to twelve times higher than state stormwater standards.

EcoSource, a Des Moines-based firm hired by C6-Zero to assess environmental damage from the blast, said it wouldn’t be able to finish cleaning up the site until March — two months later than the Iowa Department of Natural Resources ordered.

That’s according to a 17-page environmental site assessment plan filed this week. The DNR made the plan public Friday afternoon.

EcoSource’s report provided some new information about the C6-Zero operation, which owners said was “capable of re-manufacturing 800 tons of shingles a day, as well as storing another 2,400 tons of shingles” on 26 acres on the east side of Marengo.

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.

EcoSource started cleanup at the site Dec. 14, using vacuum trucks to gather 31,000 gallons of petroleum products and water from the parking lot and loading bay and store it into two large steel tanks.

C6-Zero already had put down sand to soak up oil and a sand berm to reduce runoff, EcoSource noted.

Water tests Dec. 9 showed a drainage ditch near the plant had diesel levels of 28,000 milligrams per liter, more than 12 times higher than the state standard for stormwater of 2,200 milligrams per liter.

Benzene and waste oil also exceeded state standards, the report said.

Diesel levels in water in the retention basin were 16,000 milligrams per liter.

For now, the polluted water is contained, but the stormwater basin is eventually supposed to be pumped into the Iowa River as part of a levee system that protects Marengo from flooding. The DNR has asked Marengo to hold off on the pumping until the pollution is cleaned up.

The city of Iowa City, downriver of Marengo, reported last month tests showed pollutants were not found in the Iowa River, an indirect source of drinking water for the city.

EcoSource also outlines in the plan where it would dispose of polluted water and soil. The company would get a special waste permit to dispose of the water at the Metro Park East landfill in Mitchellville.

“Once proper waste characterization has been completed, disposal of the soils will follow all state and federal regulations regarding transport and disposal methods,” the plan notes. “Final disposal methodology will be determined following waste characterization and may include either landfill disposal or field application at a certified landfarm.”

The DNR said Wednesday it will refer C6-Zero to the Iowa Attorney General for not meeting terms of a Dec. 15 emergency order that said the site should be cleaned up in 45 days.

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.

Comments: (319) 339-3157; erin.jordan@thegazette.com