Dec 04, 2018

Fungi in Bioswales Combat Milwaukee Beach Pollution

Bioswales in Milwaukee combat storm water runoff pollution

Milwaukee County’s South Shore Park Beach is rated the eighth worst beach in the U.S. in terms of bacterial contamination. The beach struggles with high levels of e. coli bacteria from a nearby fish cleaning station, trash containers and bird waste, resulting in frequent closures of swimming areas. After discovering this, Carrie Bristoll-Groll, principal civil engineer and CEO of Stormwater Solutions Eng., and her team were determined to improve the area.

“I live 3 miles from the beach and routinely run or bike the multi-use trail,” Bristoll-Groll said. “After reading the report on [U.S.] EPA rating of polluted beaches and knowing that storm water is to blame, I contacted the Friends of South Shore Park to talk to them about things were could do to intercept the runoff and improve conditions.”

After reaching out to Milwaukee County, the project grew to include more than 30 stakeholders, including government and regulatory groups, neighborhood groups, the South Shore Yacht Club and the University of Wisconsin (UW) Milwaukee School of Freshwater Sciences. The groups collaborated to combat bacteria while incorporating a safe multi-use trail and educational features. The project also included replacing a deteriorating parking lot, adding a pedestrian promenade along the lake and providing educational information on green infrastructure improvements.

The site faced several unique challenges due to its proximity to Lake Michigan. Recent rainfall led the water level to be at an all-time high, presenting complication with Wisconsin state and local regulations which require separation between the bottom of filtration systems and the groundwater elevation, Bristoll-Groll said.

The team created specially designed bioretention cells to capture storm water runoff before it discharged into the lake. What sets these systems apart is a woodchip layer infused with native fungi that thrive around plant roots. The fungi naturally target bacteria, are self-sustaining and thrive in Wisconsin’s harsh climate, making them ideal for the lakeside park. Additionally, a specialty manhole was installed to allow researchers from the UW Milwaukee School of Freshwater Sciences to perform water quality sampling to monitor the performance of the bioretention cells.

“I am most proud of my team,” Bristoll-Groll said. “The project challenged them with the goal of finding an innovative yet low-cost and low-maintenance method to combat bacteria, and they came back with a myco-filtration technique that added $3,000 to the more than $3 million project and should increase bacteria removal from 60% in standard bioswales, to as much as 90% in this design.”

Project Year:
Contractor: Terra Eng. & Construction
Designers: Adrienne Cizek, Ph.D., P.E., & Alyssa Schmitt, Stormwater Solutions Eng.
Owner: Milwaukee County Parks
Location: Milwaukee
Cost: $4 million
Size: 5 acres
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