Jefferson County panel reviews draft local rules for data centers, seeks public input

County staff on Tuesday laid out draft local rules the Economic Development Objectives Committee said could be used to regulate large data centers in unincorporated Jefferson County, emphasizing local controls on energy efficiency, infrastructure costs and siting while state regulators and utilities define rates and generation needs.

Mr. Baer, the county presenter, said the package the county is developing focuses on what local government can require: annual and, for larger projects, real-time energy reporting; power-usage-effectiveness (PUE) thresholds that start around 1.4–1.5 in year one and are expected to improve to roughly 1.3 after five years; third-party verification at the owner’s expense; and requirements that tie necessary distribution or substation upgrades to the data-center developer, not the general customer base. "Those facilities tied directly to connecting to the customer would be charged to the data center customer," Baer said, adding the county would pursue enforcement language that places compliance costs primarily on applicants.

The county presenter recommended limits on generator use: backup generators, he said, should be restricted to emergency power and permitted testing and not be used for "peak shaving, utility arbitrage, or market financial programs." He also proposed staged renewable-energy targets (an example target discussed of roughly 40 percent renewable supply at opening, rising to 60 percent within a decade), requirements for heat-recovery where feasible, and a regime for on-site monitoring and corrective action plans for underperforming facilities.

Public Service Commission staff joined the meeting by video to explain the state-level context. A PSC staff member said the recent PSC order establishes an initial tariff for large data-center users and related customers pending subsequent rate cases. The staff member described the order as setting an "initial beginning rate" derived from Senate Bill 4 and said the statutory citation referenced in the presentation materials was provided in the packet. The PSC staff explained that any future changes would be considered in a formal rate-case process in which staff audits utility books and proposes allocations to ensure costs are allocated to the entities that cause them.

Lincoln Stoll of Ameren told the committee the utility currently manages more than 10 gigawatts of generation in its service territory and has approved plans to add about 2 gigawatts by 2032 using a mix of resources, including gas plants and battery storage. Stoll said more-location-specific forecasting would be provided to the county on request.

On design and siting, the draft language discussed by county staff would treat data centers as a distinct industrial use with performance-based standards: building setbacks (suggested principal-structure setbacks around 200 feet and accessory setbacks of 300 feet in some drafts), buffer yards and screening based on building size and adjacent uses, maximum recommended building heights (an example recommendation of 80 feet was offered), façade-breakup standards to avoid monolithic walls, and strict screening requirements for rooftop and ground-mounted equipment. Baer said the county intends to preserve existing vegetation where practical and to prioritize Missouri-native plantings for buffers.

County staff said proposed compliance mechanisms would include a compliance and enforcement section in the draft ordinances, administrative-cost recovery for enforcement actions tied to proven violations, and the imposition of corrective-action plans where monitoring or verification shows noncompliance. The presenter said draft text would be circulated after additional meetings and that the Plains Zoning Commission public hearing was targeted for March 12, with council consideration expected in April.

Next steps: the committee asked staff to post or otherwise publish a plain-language summary of the statutory and regulatory changes (including the SB4 summary) for public distribution. Committee members also requested additional technical data from Ameren on local capacity and forecasts for the service area before the committee proceeds further.