News File Photo The Decorative Panels International Alpena plant appears in this August 2022 News archive photo.

ALPENA — Clogged spray nozzles could have contributed to smells noticed by residents near Decorative Panels International, the company reported in a letter to the Michigan Department of Environment, Great Lakes, and Energy filed last month.

Resident complaints earlier this year triggered an EGLE investigation of the DPI Alpena plant, resulting in multiple air quality violation notices citing the company for creating intolerable smells.

In August, DPI said it had mitigated one smell, resembling rotting vegetation, by improving aeration in its wastewater lagoon and flushing it with river water.

The company could find no source of a second identified smell, that of sweet or burnt wood, DPI said at the time.

In a Sept. 29 response to a second violation notice, DPI reported that workers had discovered that biofilter media in one of the plant’s filters was unexpectedly drying, reducing the microbial activity that removes odors from wastewater.

Watering the biofilter beds with fire hoses only increased the moisture in the beds temporarily, DPI said.

The biofilter’s bed watering system required several repairs once DPI realized in late August that the filter material was drying out, DPI told EGLE.

When the repaired system still didn’t keep filter media properly moist, inspectors discovered several clogged spray nozzles. The company shut down one press line, stopped manufacturing, and fixed the sprayers, DPI said in its letter to the state.

The company believes the repairs to the biofilter watering system will eliminate wood odors and committed to annual inspections of the system.

The company also ordered spare parts for the aeration system in its lagoon to be prepared for future problems with that system.

DPI will continue to work with an odor expert hired by the company to decide whether it should take any other steps to prevent further odor violation notices, the company said.

As of the beginning of September, the state had not yet shared specific odor complaints made by Alpena residents, requisitioned by DPI in a Freedom of Information Act request.