A detention pond meant to control stormwater runoff at the new North Lake Square shopping center on Dawsonville Highway may be leaking sediment into Lake Lanier.
Recent rains have spotlighted the potential problem that the Lakeshore Heights Neighborhood Association and nearby residents of Ahaluna Drive warned about when the development, which includes a Hobby Lobby and Academy Sports + Outdoors, was first proposed in 2012.
“Our initial concerns about a polluting pond next to the lake are real and everlasting,” Michael Proulx said. “Rather than protecting Lake Lanier, the pond has collected silty water and is discharging it into the lake.”
Proulx said he joined public works officials at the site to inspect the reported runoff last week. Changes were made to better filter the silt, he said, and the stream and lake cleared up.
But the problem appeared to have returned on Tuesday.
“From what I understand, the apparent cause is sediment from the bottom of the detention pond being suspended by rainwater running into the pond,” Public Works Director David Dockery said. “The contractor is taking steps to reduce the suspended material in the water leaving the pond.”
Proulx said he was informed that the pond should not be releasing water at such low flows, and that the problem could be exacerbated by additional runoff originating from another source.
Mayor Danny Dunagan said he is unsure if silt is leaking into the lake or whether the discharges are simply discolored water.
He added that the public works and water resources department will continue to investigate this week and work with the developer to monitor the pond.
That appears to be little reassurance for residents in the area.
“In the very near future, automotive pollutants such as oil, gasoline, radiator and hydraulic fluid will collect in the pond and will not settle to the bottom,” said Proulx, who expects those issues from increased traffic as the shopping center builds out with new stores. “These so-called small controlled releases will turn out to be a constant flow of toxic substances into Lake Lanier.”
City Manager Bryan Lackey said in an email obtained by The Times that he had met with staff to address the issue.
“I have instructed them to review the engineer’s design of the pond, our internal review and inspection process of the design and installation of the pond, and to obtain the monitoring results from the developer,” he added. “They will report back to me as to whether or not our regulations and policies were adhered to during the design and construction phases of this project.”