Restoration and maintenance improves greenbelt stormwater management

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Sunday, January 30, 2011
— Mary Frei is upset that city workers have "gutted" a section of the greenbelt near her home.

The city went too far in clearing vegetation for stormwater drainage, Frei said.

She referred to a sign at the greenbelt that says the greenbelt is being preserved in its natural state.

"I'm sorry, it's not being preserved at all," she said. "Pretty soon, you'll be able to see all the way to Milwaukee Street."

Frei, who lives near the greenbelt at 3124 Mount Zion Ave., said the section of the greenbelt is now ugly, wildlife is fleeing and residents have lost their sound barrier. She is irritated she wasn't notified about a neighborhood meeting held before work began. Her property doesn't touch the greenbelt, so she wasn't notified.

City and state officials say the greenbelt is being restored to better manage and clean stormwater.

Another neighbor, Brian Johnson, 1224 Somerset Court, said he and his wife were the only two neighbors to attend the neighborhood meeting. Johnson agreed that he can now see from Milwaukee Street down the greenbelt to Mount Zion Avenue.

City staff told Johnson that crews would not remove trees on the slopes and would cut only those along the bottom, Johnson said. Crews are doing exactly what they said they would do, he said.

Replacing the scrub brush with prairie grasses to hold the earth makes sense, Johnson said.

Tim Whittaker, city stormwater engineer, said the city normally notifies only residents whose properties adjoin the greenbelt. This is the first time someone has complained about that process, he said.

The city was forced to remove some trees in one section at the top of the slope near Frei's home because the trees had grown up through a pile of debris that needed to be cleared, he said.

Whittaker and Eric Rortvedt, water resource engineer with the Wisconsin Department of Natural Resources, answered other greenbelt questions:

Q: Why does Janesville have a greenbelt system?

A: The greenbelt acts as a natural stormwater conveyance system and as a way to preserve environmentally sensitive areas. Sections were set aside as early as the 1960s. Most cities and villages move stormwater through more expensive systems of paved channels or enclosed pipes. The greenbelt encourages water to be filtered through the ground to naturally remove pollutants. Janesville's system is a model for current development practices.

The city has about 15 miles of greenbelt. Most is on the city's east side.

Q: What is the greenbelt rehabilitation and maintenance program?

A: In 2007, the city council authorized a greenbelt maintenance program. After a generation without maintenance, staff noticed significant erosion at the bottom of sections of the greenbelt. The greenbelt had filled with invasive species such as box elder and buckthorn trees. The trees block sunlight and kill vegetation below. Rainwater, rather than soaking into the ground, courses along the greenbelt and causes erosion.

At about that same time, the DNR passed new stormwater regulations that require cities to remove 40 percent of solids from stormwater before it enters waterways.

A greenbelt is considered the best and most cost-effective way to filter pollutants and encourage infiltration. Stormwater filtered through a greenbelt sheds more than 40 percent of its solids.

Q: How does the city rehabilitate a greenbelt section?

A: Each section has its own character, so the scope varies. Crews remove invasive species from the bottom. Later, they establish native prairie, which usually takes three years of seeding. The seed mix contains 30 species of grass and wildflowers including little bluestem, switchgrass, sky blue aster, white and purple prairie clover and black-eyed Susan.

Q: Why prairie?

A: Prairie is the natural habitat. Prairie plants also send their roots deep into the soil, promoting infiltration to remove stormwater pollutants. Prairie plants encourage water to soak to the aquifer rather than run downstream to a waterway.

Q: What is the reaction from neighbors who like the trees in the greenbelt?

A: Generally, people who view the greenbelt from above think it looks great, Whittaker said. They appreciate the screening. The perception is that the trees have been there forever, not just 15 to 20 years. But the bottoms of some greenbelt sections are being carved by erosion.

Before work begins, staff meets with adjacent neighbors. Whittaker said he tries to recognize the neighbors' concerns but must balance those concerns against the required stormwater and environmental restoration. If neighbors request it, crews often leave a row of invasive trees along the rim to maintain a screen. Even though those trees shed seeds that make maintenance more difficult, the city is willing to make that compromise, he said.

Whittaker sometimes meets indiviually with people about individual trees. Crews try to save quality trees interspersed with the invasive trees, he said.

As the city works through the process, people usually understand what it is trying to accomplish, he said. Staff encourages residents to work with the city to choose trees that will survive long-term management. Sections of the greenbelt are burned on a three-year cycle to keep the invasive woody plants at bay.

Neighbors also worry about wildlife, Whittaker said. From his experience, Whittaker said the animals move back in after the work is done.

Q: What is the cost?

A: The 2011 stormwater utility budget includes $224,000 for greenbelt rehabilitation and maintenance. The work is done mostly in winter because that's when parks and public works crews are available. The next project will be in the section north of Park View Drive west of Thorncrest Drive.

Last updated: 1:30 pm Monday, March 4, 2013

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