Small step, like this, can make a huge impact. Why are more cities taking proactive approaches?
Stormwater Rethink Aimed at Flooding in Atlanta Neighborhoods
By Jen Kinney | November 23, 201
In Peoplestown, Summerhill and Mechanicsville, the city of Atlanta has decided it can’t fight nature. The three neighborhoods, largely covered in impervious surface and located in a basin that serves as the natural drainage point for the entire 1,500-mile watershed, have proven highly susceptible to flooding in major rain events, despite the city’s interventions. One block in particular, where there’s a joining of two streams and a convergence of 90 miles of combined sewer lines, was thoroughly flooded in a series of July 2012 storms that resulted in combined sewer overflows and flooded houses throughout the neighborhood.
Afterward, Mayor Kasim Reed visited the neighborhoods and made a promise: He’d correct the problem at last, with a long-term solution, not temporary fixes. Now the city is putting in the finishing touches to a stormwater management system for this region of Southeast Atlanta. With recognition that water would always flow to this point, that system uses a variety of tools, including stormwater ponds and the largest permeable paver project in the U.S. — maybe the world. It’s also displacing nearly all of the residents of that highly affected block. The city has acquired all but one of the 29 houses, and is turning the entire block into a water retention park.
The alternative, allowing the block to flood, “[is] a health and safety hazard to the public,” says Todd Hill, of the Department of Watershed Management. Atlanta still has a combined sewer system in its densest areas, so the flooding was overwhelming sewers and sending untreated wastewater into the neighborhoods. Separating the lines was deemed too expensive, so the city has largely focused on increasing capacity and diverting stormwater from the system in the first place.
“With this [new bioretention park] providing additional capacity to the system using this block that flooded, we’re able to prevent flooding on other streets and other people’s property also. We’re not protecting this one block; we’re protecting the whole community from these combined sewer overflows,” says Hill.
The city is in the final phases of acquisition, which has been ongoing since the 2012 flood event. Fourteen of the 29 flooded lots sued the city over the failure to manage the water; as part of the settlement, the city acquired their homes. The rest, the city bought at above market value, plus moving costs. Homeowners were permitted to stay until they get their credit scores in order and found new homes. One 94-year-old woman, who had lived in the house her entire life, was permitted to stay.
Understandably, not everyone was pleased. In a 2014 hearing about the plan, one resident said, “I haven’t been victimized by flooding, but I am being victimized by this plan that is going to result in me being moved from this neighborhood. … It’s not an amenity if you’re being displaced. It’s displacement.”
But the city has argued there’s not another choice. More than 60 percent of Peoplestown and Mechanicsville are covered by impervious surfaces. Cory Rayburn, who’s also with the Department of Watershed Management, says downtown Atlanta and the Braves stadium drain to that point too. The more those areas were built out after the Olympics, the more flooding the southeast neighborhoods saw. “The combined sewer infrastructure just wasn’t designed to handle the upstream areas being completely impervious,” he says.
His department has responded with a suite of tools. In addition to replacing the block with a drainage park, immediately after the 2012 flooding the city came in and made quick fixes like raising curbs and cleaning out inlets. Reed had promised actionable response within 30 days after the flooding, and delivered. The next phase included installing eight bioretention cells throughout the upland areas, plus rain gardens, bioswales and other green infrastructure.
The centerpiece of the project, begun shortly after the flooding and just completed this fall, is nearly 5 miles of streets paved with permeable surface. Spread out between the three neighborhoods, these brick-lined streets allow water to filter down into the earth without passing through the sewer system. As far as the city can tell, it’s the largest project of its kind in the world.
“We wanted to do something that would capture the stormwater, do some infiltration and reduce the peak flows on our system, and also provide an economic impetus for the people in these areas,” says Hill. Adjacent houses are seeing their property values increase because of the aesthetic value, and Hill says residents in other areas are asking if they can get the permeable pavers too. Small consolation for the displaced, but it may contribute to keeping the neighborhood inhabitable as storm events increase in the future. The entire initiative cost $66 million, which includes $15.8 million for the permeable pavers.
Prepping the entire city for a future of worsening storms may also require Atlanta to create a stormwater agency. Right now that responsibility falls to the Department of Watershed Management, which is only permitted to do pure stormwater projects in certain circumstances. Otherwise, their work must be tied to sewer or water quality work. A new municipal option sales tax will take 10 percent for stormwater, “but that’s still a drop in the bucket,” says Hill.