An experimental pond and wetland that will capture and treat stormwater runoff—and double as a new city park—is now under construction on Johnson Ferry Road just north of Sandy Springs Circle. Work should finish by next June.
For residents, the 2-acre Marsh Creek Headwaters Bio-Retention facility will include a fountain, benches and educational displays. For the Georgia Environmental Protection Division, which contributed a $388,000 grant to the total $4.6 million cost, it’s a pilot project for the state.
Small bio-retention facilities, which use trees and plants to suck up pollutants, are fairly common in medians and parking lots. But, says Sharon Izzo , the city’s stormwater services manager, “Doing it on this scale is unusual. Doing it as this scale is kind of visionary.”
It’s also controversial to the Watershed Alliance of Sandy Springs. That environmental group’s founder, Patty Berkovitz, has criticized the project since it was announced last year as a subsidy for developers who don’t contain their own stormwater and as a possible source of pollution itself through fertilizers or similar park-use impacts.
“We hope that it works, but there are some aspects of it that we’re not comfortable with,” Berkovitz said, adding that it’s “not a well-thought-out, good example of an environmental project.”
The city dismisses the criticisms as incorrect. Izzo says the project won’t use fertilizers and got reviews from the state and the U.S. Army Corps of Engineers.
And while it will handle runoff from 30 acres, including the new City Springs city center and shopping centers, that water already flows into the area, causing flooding, erosion and eventual pollution of the Chattahoochee River, city officials say. City Springs will have on-site stormwater containment as well, city spokeswoman Sharon Kraun said.
The facility will serve two main functions: containing stormwater runoff and scrubbing some of its pollutants out—especially fecal coliform bacteria, according to EPD. The city estimates the facility can hold about 90 percent of runoff from normal rains and 50 percent from heavy storms. A large pond will detain water and will have a fountain to aerate it.
The “bio-retention” part means the water first flows through an area where soils and selected plants can pick up pollutants. There is a long list of potential plantings, including variety of trees, grasses, plants and ground covers. They range from magnolias and cypress to sunflowers and Black-Eyed Susans.
“Our goal is to remove 20 percent of the pollutants,” Izzo said. How well it really works, and how much maintenance is required, they will only know when it is operational, she said. EPD will monitor it and compile the data as an example.
An observation deck will overlook the bio-retention area, Izzo said. The plans also include five parking spaces.
If the facility works well, the city has two similar facilities sketched into its 2012 City Center Master Plan — one on Boylston Drive behind the Northside Tower and the other at Cliftwood Drive and Sandy Springs Circle. There is no timeline for building them.
Another controversy with the Marsh Creek plan was the eminent domain used to take properties for its site. Land acquisition is one reason the cost is $1.1 million higher than originally announced, Kraun said.