A 15-million-gallon sewage storage tank would be built in the heart of the Ga. 400/I-85 interchange in Buckhead in a city plan nearing final design that also would alter the nearby Cheshire Farm Trail with a large water-diverting structure.

Part of the Atlanta Department of Watershed Management’s government-ordered quest to fix flooding and sewage overflow problems along Peachtree Creek, the approximately $135 million project could begin construction in early 2022 and finish in early 2024, officials said at a Feb. 15 meeting of Neighborhood Planning Unit F.

An illustration of a proposed sewage overflow storage tank and pump station facility on a Georgia Department of Transportation yard at Sidney Marcus Boulevard and the Buford-Spring Connector, as shown in a Feb. 15 presentation to Neighborhood Planning Unit F.

Since the concept was last seen in a local presentation in 2018, the storage tank has a different site from an earlier Lindridge Drive spot, now proposing to use part of a Georgia Department of Transportation maintenance yard. It also has a construction timeline two years later and an estimated budget about $27 million higher.

Aimed at flooding on the creek’s North Fork, the facility would be a companion to a similar tank system that opened in 2014 along the South Fork on Liddell Drive in Lindridge-Martin Manor. “They will work in concert together,” said Stuart Jeffcoat of HDR, which joins BenchMark Management and Barge Design Solutions on the project.

A map of the project area as shown to NPU F. The storage tank and pump station would go on a GDOT property within the area marked “Construction Site.” The diversion structure would be built on the Cheshire Farm Trail, which is shown as the dotted blue line.

Jeffcoat said the facility is part of the citywide work required by federal consent decrees and a state order. The city is spending over $1 billion on the “Clean Water Atlanta” program. Jeffcoat said the city must come into compliance with those pollution-prevention orders by July 1, 2026.

The idea of the North Fork facility is to avoid sewer overflows during major storms by diverting some of the water away from the creek and temporarily storing it in the tank until the system’s capacity goes back to normal. The facility would handle overflow from a sewer pipe 78 inches across that runs along the creek between DeKalb County and the Marietta Boulevard area in Northwest Atlanta, Jeffcoat said.

The South Fork Conservancy’s Cheshire Farm Trail runs atop that sewer line and along I-85 and the creek between Lindbergh Drive and Cheshire Bridge Road. The “diversion structure” would be built on the trail in the area of the flyover ramp from Ga. 400 southbound.

An image from the NPU F presentation showing the project’s effects and changes on the Cheshire Farm Trail.

The structure would send the excess water and sewage overflow through a tunnel under I-85 to the storage tank and a related pump station, which would stand on part of a GDOT property at Sidney Marcus Boulevard and the Buford-Spring Connector. That property is currently used for storing such materials as road salt and sand, Jeffcoat said, and would continue in GDOT use during and after construction. After the storm, the water and sewage would be pumped back under I-85 into the sewer line.

The storage tank facility also would include a “control building” with offices, “odor control” equipment and a generator, among other features, Jeffcoat said. The diversion structure on the trail would not have odor control and should not create an additional odor, he said, because it will only move sewage, not store it.

The pump station would force the trail to be shifted out of its current alignment. Jeffcoat said the designers have a “really strong partnership with the South Fork Conservancy on this” and intend to build many new features to mitigate the project. That includes widening the trail to 12 feet and paving it — which is also for the benefit of occasional access for DWM maintenance vehicles. An overlook, lighting and possibly security cameras are other features, along with retaining walls.

Part of the presentation shows how the trail would have to curve around the “diversion structure,” providing the opportunity for an “overlook” area.

The trail is part of a burgeoning network in the area whose various planners intend to eventually connect the systems of the Conservancy, PATH400, the Atlanta BeltLine and the Peachtree Creek Greenway.

The two-year construction work would require the shutting of the trail for various periods, Jeffcoat said. And, he said, traffic impacts could be expected on Sidney Marcus, the Buford-Spring Connector and Lindbergh Drive.

The sewer would not be shut down during the work and only “short-term disruptions of water service” would be expected in the project area, Jeffcoat said.

NPU F member Jack White sought the numbers of overflows in recent years and how many the facility would be expected to eliminate. Jeffcoat said he did not have that information, but that the modeling was based on reducing the likelihood of overflows during a storm of a size that occurs once every 10 years, not on targeting a specific number of overflow events.

Jeffcoat said the project team expects to have a finished design ready for construction bids by the end of March. The presentation with conceptual illustrations that Jeffcoat showed to NPU F did not appear to be publicly available. He provided the link to the DWM’s website about capital projects, which has outdated information and did not include the presentation.