Atlanta builds underground flood defense
- Georgia transportation crews restored flooded Atlanta interstates this week as city officials continued building a major underground stormwater-and-sewer storage project in Peoplestown. - The clearest measure is 20 million gallons: Atlanta’s Custer Avenue vault is designed to hold roughly 30 Olympic-size pools during heavy rain. - Construction on the Custer Avenue Multi-Benefit Capacity Relief Project is expected to continue through 2027, city and project materials say.
Atlanta’s latest flooding response has two tracks: emergency cleanup on the interstate system and a longer, slower build beneath a southside neighborhood. CBS News Atlanta reported on May 22 that the Georgia Department of Transportation was clearing flooded corridors after intense rain snarled traffic, while the City of Atlanta continued work on a large underground storage project meant to reduce future stormwater surges. The state and city projects are not the same job, but they address the same recurring problem. GDOT told CBS News Atlanta there is “a limit to how much rainfall any drainage system can take,” adding that recent drought conditions can worsen flooding when heavy rain arrives. In Peoplestown and nearby southeast Atlanta neighborhoods, the city’s answer is to create underground storage rather than try to widen already built-out streets and corridors. (cbsnews.com) ### Why put flood capacity underground instead of widening streets? The Custer Avenue Multi-Benefit Capacity Relief Project is centered on a buried “capture and release” structure that will temporarily store wet-weather flows and then release them back into the system when treatment capacity is available, according to project and engineering materials. The city’s project website says the work is under construction, and Brown and Caldwell, the engineer of record, described it as a key sewer-capacity and flood-control upgrade for the Custer Avenue sub-basin. (cbsnews.com) In dense parts of Atlanta, surface space is limited. Project materials say the underground facility will sit below a new public open space in the Peoplestown neighborhood, allowing the city to add stormwater storage without permanently dedicating more surface right-of-way to drainage infrastructure. ### How big is the Atlanta project, exactly? CBS News Atlanta reported that the underground facility is designed to hold 20 million gallons of stormwater and wastewater during major rain events. (custeravecapacityreliefproject.com) The station said that is roughly equal to 30 Olympic-size swimming pools. The broader site includes more than the vault itself. Brown and Caldwell said the project also includes storm-drain infrastructure and a greenspace component, while related trade coverage said the above-ground park area is intended to collect and temporarily store additional runoff before releasing it to the vault during wet weather. (brownandcaldwell.com) ### Which neighborhoods and systems is it meant to protect? (cbsnews.com) The City of Atlanta’s project materials place the work in the Custer Avenue sub-basin within the larger Intrenchment Creek Basin in southeast Atlanta. Brown and Caldwell said the project is intended to address combined sewer overflows and localized flooding affecting Peoplestown and surrounding neighborhoods. The design matters because Atlanta is dealing with both street flooding and pressure on older sewer infrastructure. (brownandcaldwell.com) Trade and project materials describe the vault as a way to detain peak wet-weather flows, reducing the chance that runoff and wastewater overwhelm the collection system during intense storms. ### Who is building it? (brownandcaldwell.com) The City of Atlanta Department of Watershed Management is the public agency leading the project. Brown and Caldwell said a joint venture of Ruby-Collins and BenchMark Management was contracted to design and build the underground structure, with Brown and Caldwell serving as engineer of record. Commissioner Mikita K. Browning said in the 2024 project announcement that the work aligns with the department’s stormwater-management and flood-mitigation goals. (stormwater.com) BenchMark President Eskender Abebe said at the time that the project would add to the city’s long-term resiliency plan. ### What happens next? CBS News Atlanta said the project was already more than a year in the making as of May 22, 2026. (brownandcaldwell.com) City-linked project coverage and related reporting say construction is expected to run into 2027, when the storage facility and the surface greenspace are scheduled to be completed. (cbsnews.com)
