By Ann Marie Quill

City officials say a detention pond project on the future city center site will serve as a passive, educational park for the community, but a local nonprofit group is concerned that it will pollute a stream and be a burden on taxpayers.

The city says it doesn’t want residents to think about the future Marsh Creek detention site as a hole in the ground.

“This is more like a park than anything,” said city spokeswoman Sharon Kraun.

Kraun said that the city approved this project “proactively” to help control storm water runoff, with the future city center as the impetus for the idea. “We saw the opportunity to improve downstream water quality and improve flood control,” she said.

Before the water ends up in Marsh Creek and later, the Chattahoochee River, it will be treated at the future site on one of the creek’s tributaries along Johnson Ferry Road, northwest of Sandy Springs Circle.

Sharon Izzo, the city’s manager for the project, explained what will happen to storm water runoff in the area.

The water first flows to a pretreatment area where native plants and engineered soils have been selected and placed to naturally clean the water. From there the water is channeled into a pond with a fountain, where the sun further breaks down contaminants in the water.

“Basically we’re capturing runoff from 35 acres, 74 percent of which is impervious,” Izzo said. “We’re also improving potential flooding, sending it downstream in a staged manner instead of allowing Mother Nature to do what she wants.”

But the Watershed Alliance of Sandy Springs says it has concerns the city has not answered.

Patty Berkovitz, a member of the alliance, says the city will not meet to discuss her group’s concerns. She says a spring-fed stream that’s a drinking water source sits on the site, and that the project will pollute the stream.

Berkovitz said one condition of a Georgia Environment Protection Division grant that the city received was that no stream be located at the site. “We don’t get it; the rules say you are not supposed to put a detention pond in the middle of a stream.”

Berkovitz said her group is concerned that maintenance on the detention site, including silt removal and maintaining water quality, will be funded by taxpayers — that it will be taxpayer-paid as an incentive for city center developers.

“We want to see what the engineer is proposing to do,” she said. “All that’s out there is some concept drawings with no specifics.”

Kraun said that while there is a stream on the site, about one quarter mile downstream from the future city center, it’s an intermittent stream from which no drinking water is derived. She said that the city is funding the project, and will take care of maintenance just like it would any city park.

The project is budgeted to cost about $3.5 million. Of that, $387,747 is coming from the state grant awarded to the project out of a pool of some 30 applicants.

One grant requirement is that the project provide an educational component. Part of the park’s features will include signs explaining steps in the water treatment process.

The city says it has addressed some neighborhood concerns regarding the site.

During outreach initiatives to nearby neighborhoods, residents expressed concern that the site remain a “passive” park. While the public will be encouraged to visit with walking trails and educational features, it won’t include more active amenities like playgrounds.

“People can sit and listen to the fountain,” Izzo said. “This will be an asset to the community.”

The site was chosen for the grant “because it’s such a unique project that’s not been done to this degree in the state,” Izzo said.

She explained that the state wanted to be involved to understand the project’s effectiveness in treating the storm water, and that samples are being collected pre-construction to compare them to post-construction samples. Depending on the project’s success, Kraun said that the site could serve as a model for similar municipalities in Georgia.

The city has hired engineering firm WK Dickson for design and construction management work, and will bid out the actual building of it.

A ribbon cutting is tentatively scheduled for late 2015.

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