Data centers in Fairfax County, VA
Everything on file with the regulator, added up. Every figure links to the filing it came from.
Ranked 3 of 14 counties.
Fairfax County holds 1,757 permitted backup generators across 31 sites. The median tracked county with any generator data has 248. This is one of the densest concentrations of permitted data center generation in the country.
Counties with permitted generator counts Groundwork has read from permit documents. Only Virginia publishes permits in a form that makes this countable today, so this ranking is Virginia-only — not a claim that no county elsewhere is denser.
What this does — and doesn't — mean.
These are emergency backup generators. They are permitted to run during grid outages and for routine testing — typically tens of hours a year, not continuously. A permit is a ceiling on what a site may emit, not a measurement of what it does emit.
A permit also is not a building. An issued permit establishes approval; it does not establish that anything is built, energised or running.
None of the 27 sites here that Groundwork could locate sits in a FEMA Special Flood Hazard Area.
No single permit discloses the 1,757 generators permitted in this county. That number exists only because 35 separately-published filings were added together. Each one, read alone, looks routine.
4 of the 25 permits here with a readable NOx figure are permitted at 90–99.99 tons per year — just beneath the 100 ton/year threshold that triggers major-source review and public participation. Statewide the pattern is sharper still: 70 permits sit in that band and 2 reach 100.
| Site | Operator | Permitted NOx (t/yr) | Under 100 by |
|---|---|---|---|
| Westfax Property Owner A LP/Westfax 4-5A | — | 96.03 | 3.97 |
| Amazon Data Services Inc - DCA-64 | Amazon | 96.03 | 3.97 |
| Amazon Data Services Inc - IAD - 500/501 | Amazon | 94.45 | 5.55 |
| Amazon Data Services Inc - IAD-134/135/136 | Amazon | 91.26 | 8.74 |
Read from the emissions table of each permit and labelled probable accordingly. A permit sized below a review threshold is lawful and common; Groundwork reports the pattern, and takes no view on any individual application.
Every tracked site in Fairfax County.
13 operators of record · 10 of 27 located sites draw from a basin WRI rates high or extremely high for water stress.
Virginia is the only state that publishes a data-center-specific air permit list, with the issuance document for every permit. That is why Virginia pages carry permit counts, generator counts and permitted NOx, and most other states do not.
- VA DEQ — Issued Air Permits for Data Centers — in use. 201 permits, each with its issuance PDF, read for address, equipment and permitted emissions.
Spotted an error?
Fuzzy-matched fields are labelled as such and some will be wrong. Open an issue — corrections are tracked in public and noted on the page.