County engineers describe water-modeling for data centers; developers must model demand and pay for needed upgrades

Kerry Williams, deputy of engineering, summarized how the county models water distribution and verifies that the system can maintain pressures and fire flow when large users apply to connect. He said the model includes the Scott Candler Water Treatment Plant, roughly 3,000 miles of distribution mains, storage tanks and pump stations, and that project reviewers can insert a developer's projected demand to see localized impacts.

"Keep 40 in mind. That is the minimum pressure that we needed for fire flow in the system," Williams said, explaining the 40‑PSI threshold reviewers use when assessing peak-hour plus fire-flow scenarios. He added that if a proposed development fails the model, the developer will be required to pay to upsize pipes or otherwise fund necessary infrastructure improvements and that new mains and appurtenant developer-built infrastructure must meet county specifications and be warranted for a year before acceptance.

Commissioners asked when modeling is triggered; Williams said modeling typically occurs during sewer-capacity verification when project documents are submitted and that staff can model a proposed demand at any time if provided. Commissioners discussed graywater or on-site reuse as alternatives to reduce system draw, and Williams confirmed the Emory water hub is the only nearby large-scale reuse/hub currently in place; staff said they can model graywater systems if proposed.