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.