Company filled massive manure container despite signs of a leak, DNR says

A northwest Iowa facility that captures biogas from cow manure began leaking when it was first filled in January, but its operators ignored indications of the leak and filled it further, according to the Iowa Department of Natural Resources.

An estimated 376,000 gallons of manure mixed with water leaked from a manure digester near Rock Valley. The digester is one of three in that part of the state built by Colorado-based Gevo, which processes the methane it captures from dairy farm manure into renewable natural gas to power low-emissions vehicles in California.

“When the liquid was first added to the digester, it was noted that the level dropped by five feet,” according to a recent DNR order that fined the dairy farm owner for the leak. “No investigation to the cause was done at the time and then more liquid was added to the digester.”

Farm owner Terry Van Maanen was fined $10,000 because he has ultimate responsibility over the facility’s operation, the DNR said, regardless of who actually operates it.

Gevo operators initially believed that the drop was caused by foam dissipating at the surface of the water, the order said.

The facility can hold up to about 1.5 million gallons of manure. It leaked into the ground for up to three weeks before someone noted another surface drop of more than two feet and saw manure flowing from an underground tile line into a field and Lizard Creek.

Gevo reported the leak to the DNR on Feb. 7. It’s unclear how much of the water flowed into the creek. There was no apparent fish kill, but tests of the water showed elevated levels of bacteria and ammonia.

The facility is located at Winding Meadows Dairy, which has about 2,400 cows, according to DNR data. The digester is a large, mostly underground container that captures the gas released by microorganisms as they feed on the manure. The gas is compressed and transported through a few miles of pipe to another facility, where it is refined and injected into an interstate natural gas pipeline.

To fix the problem, Gevo put a layer of epoxy in areas of the container most likely to leak, said Jacob Simonsen, an environmental specialist for the DNR who investigated the leak. He said the facility is now operational.

Gevo announced last month that it has begun injecting the processed gas into the interstate pipeline. The company said it is producing the gas from the manure of more than 20,000 cows from three dairy farms. The Rock Valley site is the smallest.

“The success that Gevo is achieving in northwest Iowa right now is the result of the team of dedicated people who are working to change the world by converting waste into useful energy, animal bedding, and soil fertilizer,” Gevo President Chris Ryan said in a press release.