I respectfully submit this comment in strong opposition to DEQ’s proposal to allow data centers to operate stationary diesel emergency generators during planned outages. The guidance outlined in APG-578 would significantly weaken long standing protections in the Virginia Air Pollution Control Regulations and shift unnecessary pollution burdens onto nearby communities. Allowing Tier 2 diesel generators to operate during a planned event contradicts DEQ’s mission to protect and enhance Virginia’s environment and to improve air quality for all Virginians.

Historically, DEQ correctly interpreted “sudden and reasonably unforeseeable events” as excluding planned outages. That interpretation protected communities by ensuring data centers prepared appropriate alternatives rather than defaulting to the cheapest and dirtiest option. The proposed revision creates an incentive for operators to treat planned outages as emergencies, even when cleaner technologies are readily available.

The guidance itself acknowledges that cleaner options exist, including portable nonroad generators, Tier 4 diesel generators, Tier 4 equivalent units, and natural gas generator technologies (see pp. 3–4). It also acknowledges that DEQ encourages facilities to adopt cleaner alternatives whenever possible. Yet this proposal would undermine that goal by allowing facilities to fall back on highly polluting Tier 2 diesel engines based solely on the level of notice received.

There are far better solutions. Data centers could rent Tier 4 mobile generators, as many industries already do. They could retrofit existing equipment with selective catalytic reduction systems to control nitrogen oxide emissions and particulate pollution. They could adopt cleaner fuels or invest in natural gas backup resources. Nothing in the proposal requires data centers to explore these options before turning to the dirtiest backup systems they own.

Communities located near large data centers already face cumulative air quality impacts from hundreds of diesel engines, cooling towers, and heavy truck traffic. Allowing planned generator operation would concentrate additional particulate matter, nitrogen oxides, and hazardous pollutants in neighborhoods that have no control over these decisions. DEQ’s role is to protect public health, not make it easier for data center operators to externalize their operating costs onto residents, schools, and vulnerable populations.

The guidance opens a loophole that large operators could exploit repeatedly. DEQ should withdraw this proposal, maintain its longstanding and legally sound interpretation of “emergency,” and require data centers to use cleaner alternatives for planned outages. Virginia deserves regulatory decisions that prioritize public health, environmental protection, and long term air quality improvement.