Avondale Estates reviews engineering plan and design proposal to stabilize Lake Aendale dam

Avondale Estates officials heard an engineering presentation on May 13 about the Lake Aendale dam that outlined urgent erosion and pipe deterioration threatening Wiltshire Drive and sketched a two‑phase rehabilitation plan. City staff said they will place a design contract with Dubberry Engineers on the agenda for the next regular meeting for board approval.

Megan Hen, senior project manager for Dubberry Engineers, told the board the inspection and geotechnical work identified ‘‘large trees and vegetation on the embankment slope, significant scour erosion near the pipe outfall’’ and deterioration in storm drain pipes under Wiltshire Drive. Hen said the scour at the pipe outfall measures roughly 10–13 feet and is likely to continue unless repaired, which could threaten the roadway.

Dubberry proposed a two‑phase approach. ‘‘Phase one addresses the most urgent storm water deficiencies, the most critical ones to protect Wiltshire Drive,’’ Hen said, listing repairs that include stabilizing the scour hole and armoring the downstream channel with riprap, removing vegetation near the outfall, and trenchless rehabilitation of the failing pipes. Phase two would pursue longer‑term embankment stability: regrading slopes, removing trees and woody vegetation across the dam, designing a seepage‑collection (French‑drain) system, and repairing erosion beneath the lake stairs.

Sam Fleming, Dubberry’s Georgia Safe Dams engineer of record, told the board the dam is not currently listed in the Georgia Safe Dams inventory and therefore not regulated under that program, but the firm is following Safe Dams guidelines in its recommendations. Fleming said removing trees may reveal existing seepage that the design must collect and control to prevent deeper instability.

Staff summarized the scope and cost in a work session following the presentation. The professional‑services proposal covers both phases and is estimated at about $190,000; staff said the city has budgeted the money in its capital program. The proposal reflects a credit of roughly $35,187.25 for geotechnical work the city already paid for. Design and construction durations presented by Dubberry were approximately six months for Phase 1 design and six months for Phase 1 construction; Phase 2 was shown as a five‑plus‑five month design and construction schedule if performed consecutively.

Board members asked whether Wiltshire Drive would need to close during construction; Hen said full closure is not anticipated and that the pipes would likely be rehabilitated using trenchless methods, though lane closures for equipment are possible. Commissioners also discussed whether a landscape or planting plan could limit woody vegetation while preserving the area’s visual character; Dubberry recommended keeping the embankment itself to grass and excluding woody plantings on the embankment.

Staff said the board will consider the professional‑services agreement with Dubberry Engineers at the next meeting. No procurement vote occurred on May 13. If approved, the design phase will develop permit‑ready drawings and construction cost estimates for future bidding.

Public commenters urged clear community notification and coordination. Bill Hover suggested adding an adjacent lakeshore/stormwater project so work in the same area could be consolidated; Kathy King asked that residents be warned well in advance if trees on the dam will be removed so the change is not a surprise.

The board did not take a final vote on the design agreement on May 13; staff said the item will return for a formal vote at the next meeting.