If you’ve ridden the Green Line in St. Paul lately, or this summer enjoyed a ball game at CHS Field in the Lowertown neighborhood, you experienced two new, innovative and complex infrastructure systems. The new systems use rain as a resource instead of letting rainfall and stormwater enter into area lakes and the Mississippi River, along with all of the pollutants that water collects.

This new method of managing stormwater is called “shared, stacked green infrastructure.” That means the system does more than one thing on a site (say, irrigating plants and/or trees), to provide additional community services or amenities beyond just managing rain runoff.

Along the Green Line light-rail corridor, for instance, the new shared, stacked green infrastructure involved installing a tree trench system—for five miles—along both sides of the transit line. One thousand new trees, as well as nine rain gardens and stormwater planters along University Avenue, absorb and filter the rainwater, preventing oil and gas that collects on the streets from reaching the river.

Moreover, signage about the green stormwater system increases public awareness. Benches in the rain gardens (which double as micro parks) add to a sense of community. The tree trench system also reduces urban heat in the summer, cleans the air and provides pockets of wildlife habitat.

Near the Green Line’s terminus, over in CHS Field, the innovative green infrastructure takes on a different form: it’s a rainwater harvesting and reuse system, the first municipal system in Minnesota. A 27,000-gallon cistern captures rainwater from the roof of Metro Transit’s operations and maintenance facility next door, which is then treated and reused to irrigate the ball field and flush the toilets.

Both of these efforts were pilot projects funded by state and regional agency grants, including the State of Minnesota’s Clean Water Fund. They were also collaborative efforts undertaken by the City of St. Paul, the Capitol Region Watershed District, the Metropolitan Council and other partners. Long-term costs for the projects’ operation and maintenance have been taken on by the local owners, resulting in an outstanding example of public-private partnerships on behalf of green infrastructure that provides additional amenities beyond simply managing stormwater.

“We’ve been working in partnership with the City of St. Paul to see rainwater as a resource and restore our natural water cycle for more than a decade,” says Anna Eleria, water resource program manager, Capitol Region Watershed District. “We’ve had to rethink how we manage and treat rainwater that falls on our land, especially because St. Paul is a fully developed city with more than a quarter-million people, and with all of the paved surfaces, we’re generating a lot of runoff.”

“On top of that, with climate change we’re seeing an increase in the amount and frequency of precipitation,” she continues. “We’ve got more rainwater to manage. So we’ve had to find a sustainable way to manage it using innovative, green infrastructure practices that filter rainwater, removing the pollutants it picks up on paved surfaces and using it to recharge groundwater.”

Next up: “opportunity sites”

Both projects helped lay the foundation for three more projects in St. Paul, which are being undertaken with help from City Accelerator. The national program, initiated by Living Cities, researches and develops sustainable ways of constructing and funding public infrastructure.

As a cohort with City Accelerator, the City has found resources “that galvanized our ability to frame innovative green stormwater management as a benefit to the development community and local cities,” says Wes Saunders-Pearce, water resource coordinator, City of St. Paul. So much so that—building on the success of the pilot programs along the Green Line and at CHS Field—the City of St. Paul and partners have developed a five-year plan with City Accelerator to look at shared, stacked green stormwater management for three brownfield sites in the city: West Side Flats, Snelling-Midway and the Ford site.

The three areas are known as “opportunity sites.” Working with City Accelerator “was a turning point” in the City’s efforts to create green stormwater management systems on these sites, adds Saunders-Pearce. The program “brought new horsepower to the table for understanding green infrastructure and financing solutions.”

The City and its partners received a combined financial stipend of $100,000 “to take a deeper dive into the barriers in our community to upfront capital outlay, and long-term operations and maintenance,” he continues. But “the primary benefit of this grant is the technical assistance the City is getting from our participation—the peer-to-peer knowledge exchange.”

West Side Flats: From brownfield to greenway

Since 2001, West Side Flats, a 40-acre brownfield site just across the Mississippi River from downtown, has been in development. Traditionally stormwater management is an afterthought in planning a development. Rainwater and runoff, once buildings are completed, are directed to underwater holding tanks or above ground ponds and released untreated back into the watershed.

Currently, a collaborative that includes the City of St. Paul has proposed a six-acre shared, stacked green infrastructure system that would include a 1,450-foot-long, six-acre greenway of plants and trees irrigated by stormwater. As the greenway winds through the site along new apartment buildings, those plants would, in turn, filter and clean the rainwater before it reaches the Mississippi. Fillmore Avenue Apartments LLC is the developer building the mixed-used neighborhood on a 13-acre parcel along the greenway.

“West Side Flats is a long-term redevelopment effort that will probably take 10 years,” says Saunders-Pearce. “We did a lot of early planning, which resulted in a completed master plan in 2015.” One of City Accelerator’s goals is to help cities in each cohort develop cross-departmental and partnership-based solutions that address a range of infrastructure funding needs, from construction to operation, maintenance and replacement costs.

“City Accelerator has helped us roadmap this new infrastructure, including important steps and milestones, in concert with our development partner, Fillmore Avenue Apartments LLC,” Saunders-Pearce says. “Being part of the City Accelerator program has given us the tools to focus and zero in, ask the right questions and find the right answers as we go forward.”

The City of St. Paul’s vision for West Side Flats is that the area will continue to emerge as a riverfront urban village connected to the Mississippi and downtown. The area’s vibrant mix of businesses and green infrastructure will result in West Side Flats becoming a benchmark and model for economic, environmental and social sustainability around the country.

Snelling-Midway: A shared, sustainable system

The Snelling-Midway site is a 34.5-acre redevelopment site that will be anchored by a proposed Major League Soccer stadium for Minnesota United. “Snelling-Midway is an ideal opportunity to incorporate a shared, sustainable stormwater management approach that not only treats runoff from the stadium, but also from the parcels adjacent to it, such as parking areas and the future residential, commercial and office parcels,” Eleria says.

“The site is also located in an ethnically and economically diverse community with a need for the social and economic benefits the stadium and innovative green infrastructure will provide,” she adds. “The site also gives the Capitol Region Watershed District a wonderful opportunity to raise awareness about stormwater runoff and help people become rainwater stewards and adopt these practices at home.”

The shared, sustainable approach is so innovative, however, that funding is a barrier. Minnesota United has committed to privately financing the stadium on 20 acres, providing a catalyst for the whole site’s redevelopment. The City of St. Paul has committed to funding infrastructure for the south half of the site, which includes the stadium and supporting areas such as parking.

“But the funding for a site-wide shared, stacked system hasn’t unfolded yet,” admits Saunders-Pearce. “To initiate the comprehensive system approach throughout the site requires a substantial investment. And the City doesn’t own any of the land.” The north half of the site is occupied by the Midway Shopping Center owned by RD Management, which is actively involved in the conversations about creating and funding green systems on the site.

“At this point, there’s a lot of alignment among the partners about the value of a shared, sustainable stormwater management system,” says Saunders-Pearce, “but there are still practical concerns that need to be resolved, from land control to paying for the infrastructure.”

Ford Motor Company assembly plant: “ambitious and aspirational”

Plans for the Ford site, a former assembly plant on 135 acres along the Mississippi River, “are truly ground breaking,” says Saunders-Pearce. Stormwater runoff from the site drains to Hidden Falls Creek, which flows to the Mississippi. Historic maps show the creek ran through the site prior to the building of the assembly plant, but the water way was paved over and buried.

As a result, a huge amount of runoff from the site ends up in the river. The partners’ (including the City of St. Paul and Capitol Region Watershed District) plan would involve re-creating and releasing the creek so it could run free through the site, meet up with the existing creek downstream and reconnect the neighborhood to the river. In doing so, the green system would serve as a national model for sustainable and resilient infrastructure redevelopment.

The plan, says Saunders-Pearce, “is ambitious and aspirational. It’s also demonstrating how significant the benefits are in comparison to investment made.” Plans for the site also include a mixed-use neighborhood with walking paths, biking trails and transit. “In order to measure what we thought cost and benefits were we assigned dollars to the benefits of environmental improvements and social impacts,” he continues. “The numbers revealed that our strategic approach would double the benefit to cost ratio compared to a conventional approach. We were also able to reduce overall costs of what were conceptually estimating by 40 percent per acre.”

Rain as resource for higher performance and value

With all three opportunity projects, continues Saunders-Pearce, “We’re really looking at how we can be more efficient by maximizing economies of scale to bring everyone’s costs down. We’re also thinking about stormwater first in design and planning, rather than last; we’re working cooperatively to minimize costs and maximize gain; and using rain as a resource for higher performance and value.”

In addition to gaining experience and expertise from other cities in its City Accelerator cohort, the City of St. Paul is taking cues from Toronto and Portland, where similar projects have occurred. “Bringing stormwater to the surface and integrating it with natural systems and vegetation to reduce environment impact is a big resiliency tool these cities have deployed, which we’re attempting to do as well,” he adds.

While the City of St. Paul “isn’t the first out of the gate” when it comes to shared, stacked, sustainable infrastructure, the City’s commitment is real. “And we’re leading nationally with what we’re trying to accomplish. We’re way out in front in terms of trying to understand how to make these systems replicable through financial mechanisms that can be institutionalized, instead of finding grants here and there.”

Over the last six years, the City and its partners accomplished strategic pilot programs along the Green Line and at CHS Field, “which has provided us with the momentum to commit to three larger and more difficult programs,” says Saunders-Pearce. “We want replicability, so each project can inform the next one. We’ve moved past the pilot phase. Now, we’re deeply engaged with a program in which we can really understand costs and capacity, efficiencies and impact.”

“We want the average citizen to know we’re trying to get the most mileage out of every dollar we spend on stormwater management at these sites,” he adds. “We know we need to do more with less. At the same time, we’re working to connect our communities and our residents with our urban ecosystem, so everyone understands how and why sustainable stormwater management infrastructure will improve their quality of life.”