Hoan Bridge smoke due to Milwaukee Sewage District

Drivers heading across the Hoan Bridge may have noticed it's a bit smokier than usual, a temporary condition that could occur more frequently on windy or humid days.

The Milwaukee Metropolitan Sewerage District is making some needed repairs to the large air ducts that feed the exhaust into the 350-foot-tall smokestack, a familiar site on Jones' Island. During the repair process, the exhaust will be released directly on top of the building where the district makes fertilizer.

The exhaust will be coming straight out of the top of the building, "so it could look like maybe there's a fire," warned Bill Graffin, the sewerage district's public information manager.

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But it's not. It's the same exhaust that's always released from the tall smokestack. There's just more of it.

Although the sewage district doesn't expect any traffic issues, certain weather conditions may cause some visibility and freezing issues, according to Graffin.

Here's what to know about MMSD's exhaust project.

The sewage district makes a fertilizer called milorganite out of organic matter recycled from sewage and microbes that clean wastewater. One part of that process includes putting the microbes and organic matter into massive dryers the size of Greyhound buses that kill any leftover pathogens, Graffin said.

The waste from that process goes into pollution scrubbers, which releases steam from the tall smokestack on Jones' Island.

Last week, during routine maintenance, sewage district employees noticed some cracks in the ducts that feed the exhaust up the 350-foot-tall smokestack.

Until the ducts are repaired, the sewage district is changing how it vents the exhaust. Drivers will see a bunch of 10-foot-tall stacks, rather than one tall smokestack, on top of the building where the fertilizer is made.

The smell will be familiar, though. It's the same exhaust that comes from the smokestack on Jones' Island.

The exhaust still complies with air permits from the state's Department of Natural Resources. The exhaust is put through pollution prevention equipment before being released into the atmosphere, according to the release from the sewerage district.

The change went into effect Monday and will likely be finished before the end of the year as long as new issues don't arise, said Graffin.

The sewage district doesn't anticipate a lot of traffic issues with the temporary changes. But that depends on the weather.

There may be some visibility issues if the wind carries the smoke plumes across the bridge. There may also be a freezing issue if the air is really humid.

If that's the case, the sewage district will scale back, turning off some of the stacks. It can also shut the whole thing down, Graffin said.

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The sewage district also is putting up signs to warn travelers of these potential hazards.

Caitlin Looby is a Report for America corps member who writes about the environment and the Great Lakes. Reach her at [email protected] or follow her on Twitter @caitlooby.

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