Union City Hall

 Plastic pipes could soon be allowed under city of Union streets.

Union City Engineer Jonathan Zimmermann proposed amending the city’s code at Monday’s planning and zoning commission meeting to allow a new type of plastic pipe under certain city streets. 

The plan board backed the suggestion and instructed Zimmermann to return at a future meeting with a proposed ordinance authorizing the change.

Zimmermann said the city’s code requires concrete pipes under pavement. Outside of pavement, the rules are more lenient and allow for some plastic piping.

For some recent projects not under pavement, the city has used a new HP plastic pipe. The results have been positive, Zimmermann said.

The city has used the plastic pipe on projects near Prairie Dell and Denmark roads. 

“We have used it and it held up well,” he said. 

The HP pipe, which Zimmermann called relatively new, is much stiffer than older plastic pipes. He said it’s more “forgiving” when working on installation.

Concrete pipes are the most forgiving Zimmermann said, but also the most expensive — at least when it comes to the installation. The cost of the pipe itself might not vary too much, but less equipment is needed to install a plastic pipe, he said. 

By switching to plastic, the city could save some money on stormsewer and sanitary sewer pipes.

Zimmermann said the biggest issue with the plastic pipe is “how it’s built.”

“It’s more finicky,” he said. “With concrete, when you put it in the trench, it’s nice and round. With plastic, you have to compact materials around it. That’s the only way it stays round.”

Zimmermann said he would support the switch to plastic only under certain roads. He said before considering on making the switch he looked at how other municipalities were dealing with plastic pipe.

During his research, Zimmermann said he really liked how the city of Columbia implemented plastic pipes. He said Columbia created a matrix that showed what type of pipe was permitted on what type of street.

For example, roads that are classified as local roads don’t get as much traffic and can have plastic pipes. Major roads, ones that see a lot of traffic, get a higher quality pipe like concrete.

Zimmermann said he thought some guidelines mimicking Columbia would work for Union. He suggested, if the board supported the idea, coming back with a matrix like Columbia and a revised ordinance.

He said the ordinance would cover things like pipe depth, bedding and cover requirements. 

The plan board will review the proposal before making a recommendation to aldermen. The final decision on if the city can use plastic piping under roads would come from the board of aldermen.