AltEn pilot project resumes using new, less mechanical process

AltEn pilot project resumes using new, less mechanical process
Piles of an estimated 115,000 tons of contaminated waste grain from the closed AltEn ethanol facility await hauling away, to the Douglas County landfill. (Paul Hammel/Nebraska Examiner)
June 19th, 2024 | Paul Hammel - Nebraska Examiner

MEAD, Nebraska — A pilot project to discover the best way to remove a 14-acre pile of pesticide-contaminated “wet cake” from the site of the now-notorious AltEn ethanol plant here has resumed after a delay that was blamed on equipment breakdowns and a change in the process. 

Two backhoe-like “excavators” began work Monday to mix the wet cake — the grain left after the ethanol distilling process — with bentonite so it can be shipped to a landfill outside Omaha without creating odor or dust issues.

The disgusting odor from the spent grain had been described as “putrid” by nearby residents of the plant, which was ordered closed by the state in February 2021 after the owners failed to comply with several orders to properly clean up the piles of wet cake and wastewater left behind.

The closing came after a leak at the plant spilled millions of gallons of contaminated wastewater into a nearby stream and neighboring land.

Unlike traditional ethanol plants, which turn field corn into alcohol, the AltEn plant had begun in 2015 to use expired seed corn, which is coated with a variety of toxic pesticides.

Worries about health risks 

After a nearby landfill stopped accepting the waste grain, it began piling up at the site south of Mead, spawning complaints as it grew to cover 14 acres and contain an estimated 115,000 tons.

The closure, and revelations about the use of expired seed corn, drew national attention and concern to the site about health risks and contamination of soil and water.

Last fall, NewFields, the company hired by seed corn companies to clean up the AltEn site, shipped about 10,000 tons of the spent grain — or about 515 truckloads — to the Pheasant Point Landfill near Bennington, northwest of Omaha in Douglas County. Cold weather suspended the work in November.

Initially, officials had hoped to resume the pilot project in late April or early May. But Bill Butler, a partner and senior engineer with NewFields, told the Examiner on Tuesday that it took more time than expected to shift to a new process of mixing the wet cake with bentonite to avoid mechanical breakdowns that slowed the work last fall.

“Everything we do takes a lot of time and preparation — getting equipment lined up, materials and contractors lined up,” Butler said. “Even though people driving by might not think a lot has been going on, a lot has been going on in the background.” 

Last year’s work proved that mixing the wet cake with bentonite and then encasing it in plastic for truck shipment — like a huge burrito — was effective in eliminating odors and dust, he said.

But a tub grinder-like “pug mill” used last fall to mix the materials broke down too frequently, and while effective, it worked slowly, Butler said. 

New process being tried

A new process is being tried this year, using excavators to mix the wet cake in the pile before shipping it away. He said it involves less material handling and carries less of a risk of mechanical breakdown.

“It does create more potential of odors and dust so we want to assess if we can do this safely and efficiently,” Butler said. “That’s why we’re doing a pilot project.”

He said his firm hopes to haul away another 485 truckloads — about 40 to 60 a day — of material in the next five to six weeks and then make a decision about the best process for disposing of the wet cake.

Butler said it was impossible to say how long it will take to remove the entire pile until it’s determined how it will be done.

He added that much progress has been made in treating the wastewater left by AltEn owner Tanner Shaw when the plant closed in 2021. Butler said all of the water should be treated by the end of the year, and the treated water will be deposited on nearby crop fields next year.

As of May 12, 84.7 million gallons had been treated, with an estimated 30 million gallons remaining, officials have said.

Butler said about 90 soil samples have been taken in areas underneath the wet cake pile. So far, he said, tests show a low risk of pesticides contaminating groundwater in the area.

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