Campus Stormwater Discharge Reduced Due to Green Landscaping

The University of Wisconsin at Milwaukee has installed green rooftops, bioswales, and other natural landscaping projects that have lead to a dramatic decrease in the water the campus discharges into the Milwaukee sewer system.

Description

The University of Wisconsin at Milwaukee has been reworking their campus to reduce stormwater discharge. Seven buildings on campus have green roofs incorporated into their design, including a Wisconsin native dry-prairie, one with solar panels in the landscape, and a vegetable garden used by a campus café. These green roofs will absorb water and heat more effectively than traditional roofs ever could, while benefiting wildlife by providing habitat. A 5,000 square foot spiral garden on campus catches rainwater drainage from some of the green roofs and other traditional rooftops to decrease runoff into Lake Michigan. The garden and two cisterns that double as fountains at the end of it slow the flow of water, allowing it more time to seep into the ground. The presence of native plants also slows the progress of the water, increases absorption in the landscape, and filters nonpoint source pollution that collects on the rooftops and in the nearby parking lot.

Resource Challenges Addressed

• Excess runoff

• Erosion

• Pollution

• High energy use

• Lack of wildlife habitat in urban spaces

Location

Milwaukee, Wis.

Approximate Cost

$2,000,000

Key Partners

Great Lakes Restoration Initiative, Milwaukee Metropolitan Sewerage District, University of Wisconsin at Milwaukee, and WE Energies

Types of Jobs Created

Landscape designers, biologists, university research assistants, construction workers, truck drivers, and general laborers

UNIVERSITY DECREASES RUNOFF

The native prairie green roof on top of the Sandburg Commons. Green rooftops can absorb rainwater, slowing the time it takes for the water to reach the sewer system and helping the sewer cope with heavy rain events. Photo credit: Jim Wasley.

Results and Accomplishments

The spiral rain garden in combination with the green rooftops are estimated to reduce average stormwater runoff into the city’s sewerage system by 97 percent. This impact is in part due to a large area of impervious surface whose runoff was diverted into the spiral rain garden, providing the space and time for water to absorb into the landscape instead of running off into Lake Michigan.