How a development boom on the West Side has put St. Paul’s sewer system to the test

Stop me if you’ve heard this before: A developer has a big plan to build apartments on a marginal piece of land in the shadow of downtown. But then a small technicality stands in the way, and the new apartments have to be put on hold.

This time, though, it’s not community opposition or a zoning problem or angry neighbors or financing that are the hurdle. Instead, a sewer pipe is the wrong diameter. 

The problem is that a recent development boom on St. Paul’s West Side has put the city’s century-old sewer infrastructure to the test. While most of the system is in good shape, there are growing pains in some areas as housing rises amid longtime industrial land. While it’s a good problem to have, it means the city will have to figure out ways to add capacity and make sure that the wastewater keeps flowing downhill.

A fine lining 

There’s no infrastructure that’s so important, yet so ignored, as a city’s sewers. Every single person uses them every day, and they can make the difference between clean water and cholera. But nobody wants to think about how they work, or what happens when you flush the toilet. Every once in a while, though, the out-of-sight pipes come into focus.

“Our basic sewer capacity is in great shape, even now,” said Sean Kershaw, St. Paul’s director of public works, giving me a big picture look at the city’s underground pipes. Kershaw, who has a background in policy and communications, took over the job last year. He’s an admitted nerd when it comes to sewers, preaching the gospel of utility maintenance to anyone who will listen.

“It’s not the age that’s the problem: They were built for industrial use, but the sewer has reached its capacity,” Kershaw explained. “Most of them are in good condition, even sewers that may be 120 years old, and we’re in the process of going in and lining them.”

That work involves adding a thin layer of coating to the sanitary sewers that transforms the old pipes into a modern durable network. Using what Kershaw describes as “a fascinating plastic-based material” — a resin-saturated felt tube inserted through the city’s trademark utility covers — the city can line about 10 miles of sewers each year, though the work has only just begun.

The newly lined pipes make up only 20% of the 800 miles of sanitary sewers in St. Paul and they form an elaborate underground web. They link every home and toilet in the city to the Met Council’s system of interceptors, flushing the city’s wastewater to the massive treatment facility at the Mississippi’s Pig’s Eye Lake. 

Pipe dreams

It wasn’t always so neat underground. Twenty-five years ago on Harriet Island, only a few dozen feet from today’s sewer chokepoint, then-Mayor Norm Coleman celebrated the completion of St. Paul’s Combined Sewer Overflow effort. One of the largest city infrastructure projects in decades, the 10-year, $332 million construction project (around $700 million in today’s dollars) dug up streets all over the city to add a separate stormwater system. Before that point, during hard rains raw sewage would wash into the Mississippi River or flood people’s basements (!), leading to significant pollution problems. After the separation, toxic overflows became a rarity.

At the time, nobody envisioned that a far corner of the West Side Flats area, along Water Street and Harriet Island, would become a hot destination for housing. For most of the 20th century, this part of St. Paul had been a mix of industrial land uses: warehouses, a garbage processor, a marina and even a historic brewery.

That’s changed in the past few years, as the city’s ongoing housing shortage has spurred demand. Development has even been plodding through the half-empty West Side Flats, expanding downtown density over the Mississippi. The new Cordelle apartments, a 136-unit building next to Harriet Island park, added housing and density to similar projects a few blocks to the east. Today the building’s pinball machines, a swank lounge and exercise machines are on display from the new Water Street sidewalk, a new addition to the industrial area that’s offering a free month’s rent on new leases.

But any other new housing is on hold until the sewer chokepoint is sorted out. The situation is rare for St. Paul, and there aren’t that many spots where the sewer system is struggling to meet demand and land-use changes. But if the city wants to see new housing built, and something will have to be done.

“The land use is changing,” said Nicole Goodman, the recently appointed director of St. Paul’s Planning and Economic Development Department. “All the way back in 2002, there was a planning effort that identified the area west of Wabasha as redeveloping into residential and commercial uses. With how development works now, there’s this pressure that we’re starting to feel, interest in developments happening.”

In this case, an Edina-based developer, Buhl Investors, plans to build about 300 new apartments on the site of warehouses and parking lots. Often sewer and infrastructure improvements are split costs between the city and developer. In this case, the unique challenge has left city staff looking for some funding to figure out how to expand the sewer system for this corner of the city. At this point, nobody’s yet sure how much it’ll cost or where the money will come from.

“We’re working with an engineering firm to figure out what it looks like, and what is the need,” explained Director Goodman. “What are options from an engineering standpoint? There are several possibilities, but they have different costs and complications.”  

In the meantime, the Planning Commission is approving the zoning changes, in the hopes that the new homes will someday be built. It’s not often that a narrow pipe stops new housing, but hopefully, the sanitary sewer doesn’t block new people from living in St. Paul for very long.