DeKalb officials receive Snap Finger Basin update; consultants recommend targeted inspections, some pond decommissioning and a bioretention pilot

DeKalb County commissioners heard an update July 14 on a detailed phase of the county’s stormwater master plan focused on the Snap Finger Creek watershed, where consultants from Arcadis said they have inspected critical culverts and detention ponds and will use the findings to build a prioritized capital improvements plan.

Arcadis senior project manager Rich Bruel and colleague Anwar Ahmed told the Public Works and Infrastructure Committee that the firm had mapped about 11,000 stormwater assets in the Snap Finger watershed and selected roughly 1,100 of the highest-consequence elements for closer inspection. The team said it has completed a little more than half of the initial inspections, using pole-camera and drone-like devices equipped with LiDAR and thermal cameras to get condition data from inside culverts and long pipelines.

The consultants described the inspection approach — including “pole camera” checks for deep pipes and a caged drone that collects high-definition video and a LiDAR-derived 3-D profile — and said the field work informs condition ratings, safety assessments, and an updated risk assessment that will feed a capital improvements plan. “We took that 11,000 and went down to 1,100 of the ones that are going to be the most impactful if they fail,” Bruel said.

Why it matters: The county’s strategic master plan previously cataloged about 77,000 stormwater assets at a high level. The Snap Finger work is the “next level down” officials said — moving from inventory into condition assessment, hydrologic and hydraulic modeling, and project prioritization to reduce the risk of road closures, property flooding, and other failures.

Insp…