Amboy working to fix pollutant levels in Green River

AMBOY – Until pollutant levels in Green River near Green River Oaks Resort normalize, officials are advising people not to come into unnecessary contact with the water near the resort’s campgrounds.

Organic material – not human waste – from Sensient Technologies Corp., 25 E. Main St., is likely the culprit, said Matt Hansen, vice president of Willett, Hofmann & Associates, the engineering firm consulted for the plant’s expansion.

Melanie Arnold, a spokeswoman with the Illinois Department of Public Health, said anyone upriver from the city’s wastewater treatment plant, where the pollutants are entering the river, need not be concerned. But near the campground?

“It depends on the recreational activity and who has access to it,” she said. “If you have an open sore, there would be a risk of infection. It’s similar to a situation with a flood where there’s a problem with a septic system, and you don’t want anyone with open sores in contact with that water.”

The Amboy plant is part of the Sensient Flavors division of Sensient Technologies Corp., which makes and markets flavors, colors and fragrances that are used in foods and beverages, cosmetics, pharmaceuticals, and other specialty chemicals. Water is a major component of its process.

Over the past several months, wastewater from its pretreatment facility has arrived at the Rockyford lift station with levels of organic material that the facility can’t properly filter.

Nor can the wastewater treatment plant at 768 Rockyford Road, about a mile upstream from the campgrounds, where the water from the plant is discharged into the river, Hansen said.

“We think that’s contributing to additional loading, which the Amboy plant is not designed to handle,” he said.

In June, Sensient began an expansion that will add 36,000 square feet and about 50 jobs, boosting its workforce to 180. During the expansion, however, its pretreatment facility couldn’t be operated at full capacity at all times, Hansen said.

As a result, the biological oxygen demand – amount of oxygen needed by aerobic organisms to break down organic material – and suspended solids levels in the river were at 80 and 260 milligrams per liter in March and April. Illinois Environmental Protection Agency standards are 37 and 25 milligrams per liter, respectively.

In addition, and perhaps as a result, the amount of sludge in the wastewater plant’s lagoons has increased faster than expected.

Mayor Tom Nauman said the city is communicating weekly with the EPA to rectify the matter, a cleanup he characterized as “routine.” Buildup was removed from the lagoons 16 years ago, and the city had expected another cleanup wouldn’t be necessary for 20 years, he said.

Now that Sensient has installed a surge tank, where the waste will be conditioned before going through its pretreatment plant, the levels of pollutants should come down, Hansen said.

In the meantime, the EPA advised the city to install additional aerators to increase dissolved oxygen levels in the lagoon, as well as post signs along the river at the campground. The aerators are expected to arrive next week.

Hansen said a village of Amboy’s size could go up to 40 years before sludge has to be removed.

“We’re seeing a heavier load than a community with no industrial sewer customers,” he said.

The good news is that the sludge has nutrient value, and once it’s tested, can be used as fertilizer.

“Once we find farms that are willing to take it, some of it can be reused, you might call it,” Hansen said.

Neither EPA nor Sensient officials could be reached for comment.