It's a beautiful morning in early September. U of M students bike and scooter across University Avenue and pass through the gates onto Pleasant Street on their way to class. All around them are impressive feats of architecture, from the ornate splendor that is Folwell Hall to the arched windows of Jones Hall.
What these passersby probably don’t notice is that a middle-aged woman in a blazer and a T-shirt decorated with the pi symbol is climbing over the greenery inside the oval that divides this portion of Pleasant Street. This is Cathy Abene (B.A. ’99), principal civil engineer in charge of managing the U of M’s water, sewer, and stormwater systems.
Abene, who is also a commissioner for the Minneapolis Park Board, pauses to point at a nearby covered metal grate, through which it’s possible to spot a pipe jutting out above a layer of standing water. This pipe is purposely small—the opening is 12 inches— which slows the rate of water flow into the city’s storm sewer during rainfall. It also keeps water in the system longer, which gives nearby trees more time to drink it.
Abene notes that an impressive feat of engineering lies below the pavement here: a network of tunnels and stormwater systems that ensure water from a thunderstorm or blizzard makes its way safely into the Mississippi River instead of flooding campus.
In 2015, the University repaved Pleasant Street and decided to overhaul the surrounding five acres. The U of M replaced an almost 100-year-old stormwater sewer system with cutting-edge improvements that not only absorb as much water as possible, but also filter out leaves and grass and the pollution they carry with them. In addition, the sidewalks along Pleasant Street now are lined with rows of permeable pavers spaced far enough apart to allow water to seep into the ground. There are also trees planted just below street level, which receive water from the urban stormwater runoff captured in the trenches where they are planted.
And, below the shrubs inside the Pleasant Street oval—which themselves store water and then release it slowly back into the atmosphere—a network of pipes is specifically designed to slow down the rate of water flow.
This below-ground infrastructure is one example of how the University is literally laying the groundwork for a future Minnesota in which more unpredictable weather events will occur.
All these efforts also lessen the problems that can happen when fast-moving water must travel through discharge pipes into the Mississippi—including flooding, increased erosion, and additional pollution making its way into our waterways.
“Before Europeans were here shaping and forming the land, the water would have [naturally] gone into the river,” Abene explains. “But it would also have gone into the ground.”
Today, the sidewalks and freeways and parking lots and rooftops that are an integral part of the urban environment mean that stormwater runoff no longer simply sinks into the ground, but travels sideways. That means as we redevelop the landscape, our human activities often result in more and more stormwater runoff. That, coupled with changing precipitation patterns, causes the amount and rate of stormwater runoff to increase, causing flooding and washing contaminants into Minnesota’s lakes, rivers, streams and wetlands.
Abene is proud to showcase this example of the University’s investments in “green infrastructure,” with systems that mimic how water naturally moves through the environment. But while she’s proud of this forward-thinking example, that doesn’t mean she doesn’t have other concerns.
“Oh, I worry about the old stuff,” she admits, referring to the 50- to 100-year-old pipes that support water needs elsewhere on campus.
According to rainfall data compiled by FiveThirtyEight, a data-driven news company, Minnesota is getting wetter overall, even though the past two summers have been very dry. Over the course of the last century, there have been more storms that produce heavy rainfall and the strongest of these have become more intense.
Since 1973, the state has experienced 11 “mega-rain events,” which is when 6 inches of rain falls over 1,000 square miles, with the center of the storm dropping more than 8 inches of precipitation in a short period of time. Eight of those storms have occurred since 2000; 2016 had two. These intense, abrupt rainfalls mean that water may find itself with no place to go.
“The challenge to all cities is that the size of [our stormwater] pipes was designed for storm events that were happening every 100 years, and not every 50 years,” says Ryan Noe (M.S. ’15), a geospatial developer at the U of M. “[That] means you're going to have more wear and tear on infrastructure that’s not designed to handle extreme events that frequently.”
Those overwhelmed pipes could mean more flooding in our future, a phenomenon that’s already being seen elsewhere. (See “That Water Has to Go Somewhere”)
In his previous job, Noe was a researcher in a lab run by Humphrey School of Public Affairs Associate Professor Bonnie Keeler (M.A. ’07; Ph.D. ’13). Noe says that current stormwater infrastructure is designed using metrics that do not factor in climate change, which is contributing to mega-rain events. Using high-resolution regional simulations of Minnesota’s climate at the end of the century, Noe and his collaborators created a proof-of-concept data set to better represent the extreme precipitation events that infrastructure will face in the future. (For more on Keeler’s work, see “Water is for Everyone”)
Unfortunately, it’s not just floods that worry the experts.
“The analogy I use is that precipitation starts to act like a school bus, but instead of picking up kids along the way, it picks up pollutants,” explains John Bilotta (B.S. ’93; M.S. ’02), a research project specialist with the U of M’s Water Resources Center (WRC). The WRC is a center for environmental research that promotes freshwater management across Minnesota.
Bilotta leads the Minnesota Stormwater Research and Technology Transfer Program through WRC. “In many cases, the pollutant [picked up by precipitation] is sediment or dirt. But other pollutants attach themselves to the tiny bits of sand and silt and clay, including phosphorus and nitrogen and heavy metals.”
These pollutants are not only a concern for our drinking water (see accompanying story “On Tap”); they can also compromise traditional uses for Minnesota's bodies of water. That might mean beach closures due to algae blooms or fewer fish in our favorite lakes. (The majority of Minnesota lakes are already classified as impaired for one or more reasons, according to the Minnesota Pollution Control Agency [MPCA].)
Bilotta and his colleagues at WRC conduct over $1 million a year in research on innovative practices and policies that communities and community leaders can use to help combat these challenges. They pair that research with training programs they’ve developed to help stormwater practitioners and policymakers in Minnesota communities.
One example is the Clean Sweep for Water Quality (CSWQ) program, run through U of M Extension. It educates businesses and homeowners that street cleaning isn’t done simply to make streets look nicer, but to protect lakes and rivers from pollution that exists in leaves and tree seeds.
Working with the MPCA, the CSWQ program helps cities and town enhance their street cleaning systems—including employing highly powerful vacuum systems—as a way to reduce phosphorus, microplastics, and other pollutants that can end up in bodies of water.
“The program incentivizes cities and municipal separate storm sewer systems [known as MS4s] to do enhanced street cleaning because it is such an effective tool,” says Maggie Karschnia, an Extension educator who works with WRC and Minnesota Sea Grant, a joint federal University program that uses science to help protect water quality in Lake Superior and inland lakes.
CSWQ provides training on how to use the Minnesota Street Sweeping Calculator, a tool that estimates the amount of pollutants removed through street sweeping. Once calculated, the credits can be used to meet the requirements of a city’s stormwater management plan. In 2023 the program plans to expand to cities across the state.
WRC also promotes green infrastructure. “Mother Nature, between her roots, her soils, and her plant landscape, was able to manage [stormwater] successfully without quality and quantity issues,” says Bilotta. “So we’re trying to exercise not the power of pipes and concrete, but the power of plants and soils to help us manage this urban stormwater challenge that we have.”
At the Twin Cities campus, this philosophy drove not just the redevelopment of Pleasant Street but also the 17th Avenue Residence Hall, which is landscaped with native grass plantings and has a “green” rooftop covered in succulent plantings. Stormwater is captured by these plants and through porous pavers nearby and then collected in an underground cistern which stores up to 35,000 gallons of runoff generated on the site. This harvested rainwater is treated with ozone to kill bacteria and then used to flush toilets in the dorm—the first system in the state to use this technology.
All of which thrills Abene.
“I’d love to do a ribbon-cutting ceremony someday on a pile of dirt where there is a pipe buried eight feet below ground,” she says. “I know people care about the big buildings, but what gets me excited is to figure out how to steward aging, decrepit, failing infrastructure.”