Part 12 of 13 in Thirteen Records. The long article, Data Centers Don’t Have an Environmental Record. They Have Thirteen of Them., rates thirteen kinds of environmental complaint against data centers. This series takes them one at a time.
I work at a local ISP in Northern Illinois and co-founded FD-IX, an internet exchange. I have no customer, vendor, or interconnection relationship with any facility or developer named here and no financial position in any of them beyond broad-market index funds. My industry grows with infrastructure investment in a general way, which is an indirect interest; the full disclosure is at the top of the complete article.
A data center holds three things that can go wrong chemically: the foam in the generator yard’s fire suppression, the fluid in an immersion-cooled hall, and the batteries that carry the load until the generators start. Only the first has a documented groundwater record, and that record belongs to sites where aqueous film-forming foam was tested or discharged, which is why “PFAS” arrives at hearings with more certainty than the evidence carries.
This post rates three chemical claims: the PFAS foam concern, which is Regional and has an accountability failure attached to it; immersion cooling fluids, which are plausible and undocumented; and fire risk, where the data that would settle it does not exist in public. It ends with the one line that belongs in every application and almost never appears: the fire suppression agent, named, for the generator yard and the data halls separately.
How the ratings work. Each complaint below is stated the way it usually arrives at a hearing and rated on the scale the full article uses. Systemic: documented at compliant facilities across multiple geographies. Regional: real, but only under specific geographic or operational conditions. Isolated: documented at one or few facilities due to misconduct or atypical design. Exaggerated: the concern is real but the figures are permit ceilings or worst cases, not operating norms. Selective: a legitimate concern applied only to data centers, not to comparable land uses. Misattributed: the harm is real but the source, geography, or cause is wrong. Contested: a plausible mechanism exists but causal documentation at compliant facilities does not. Fabricated: no credible evidentiary basis exists. Where I say I found no record of something, that means a search of public sources through October 2026, not paid databases or records requests.
Chemical Hazards
Claim: Data centers will contaminate groundwater with PFAS from firefighting foam. Tier: Regional. Sites where foam was tested or discharged.
Aqueous film-forming foam (AFFF) is the documented concern. Its per- and polyfluoroalkyl substances (PFAS) are associated with groundwater contamination where suppression systems were tested or discharged, and PFOA and PFOS are CERCLA hazardous substances. [15a] Their federal drinking water limits of 4 parts per trillion remain in place; EPA’s May 2026 proposals would keep them, let systems that request it take until 2031 to comply, and rescind the limits for four other PFAS; neither is final. [15d] Two distinctions keep the concern from being misapplied. AFFF is a foam for flammable-liquid fires, which at a data center means the fuel and generator yard, not the data hall. The clean-agent gases common in data halls, FK-5-1-12 and HFC-227ea, are not foams and do not reach groundwater the way foam does, but they are PFAS under some definitions, though not under CERCLA, so “PFAS-free” is a claim to check against the agent named in the fire protection plan. As of May 2025, fifteen states, Illinois among them, had banned the sale of PFAS-containing firefighting foam. [15b] Operators describe a transition to fluorine-free agents, and there is no public, independently verified timeline for completing it. The industry has not published one. That is an accountability failure.
Claim: Immersion cooling fluids are a new toxic risk. Tier: Contested.
Immersion cooling submerges servers in non-conductive dielectric fluid and is growing in high-density AI facilities. I found no peer-reviewed lifecycle environmental data for these fluids at commercial scale. The concern is plausible and undocumented, which is why an application for an immersion-cooled facility should name the fluid, the volume on site, the containment, and the disposal route.
Claim: Data centers are a fire hazard to the neighborhood. Tier: Contested.
Battery systems at data center campuses are typically installed to NFPA 855, which binds where a jurisdiction has adopted it, and tested against UL 9540A, a method for evaluating thermal-runaway propagation. [16a] Fire is a real event class wherever dense electrical equipment runs. Uptime Institute’s annual outage analyses find power supply, not fire, the leading cause of significant outages, but outage data does not count fires that did not interrupt service. [16] Settling the question would take insurer, fire department, or NFPA incident data, and I found no industry-wide fire dataset. Cardinal’s agreement puts battery storage other than in-rack backup in standalone buildings at least 50 feet from other structures, with a fire safety plan approved by the fire district. [11x]
What to ask for. Fire suppression agents identified by name in the application, for the generator yard and the data halls separately, since “PFAS-free” means different things for a foam and a clean-agent gas and no public tracking exists of which facilities have completed the AFFF transition. [15b] Illinois banned the sale of PFAS-containing foam, so a new campus should have no reason to resist the question. The diesel tank schedule and the SPCC plan belong in the same submission. [15c] For an immersion-cooled hall, require the fluid’s name, the volume on site, the containment, and the disposal route. For battery storage, require the standard the installation is built to, the UL 9540A test results, the setback, and a fire safety plan approved by the fire district, which Cardinal’s agreement does with a 50-foot standalone-building requirement. [16a][11x] Put the end-of-life disposal of batteries, dielectric fluids, and suppression agents in the decommissioning plan described in the land post.
The accountability failure. Operators describe a transition to fluorine-free agents, and there is no public, independently verified timeline for completing it. The industry has not published one. A council cannot fix that, but it can refuse to accept “transitioning” as an answer for its own site.
This is part 12 of 13 in Thirteen Records, a series that takes the long article Data Centers Don’t Have an Environmental Record. They Have Thirteen of Them. one topic at a time. Previous: light at night and human health. Last: electromagnetic fields, where the source is the substation and the standards were not built for the question.
Cover photo: Kecko / Flickr via Wikimedia Commons, CC BY 2.0
Citations
[11x] United City of Yorkville, Ordinance No. 2025-77, approving the Planned Unit Development Agreement for Project Cardinal, passed November 10, 2025 (7-0), signed by the mayor November 13, 2025, published November 14, 2025; city-posted executed copy, mayor’s signature and clerk’s attestation dated November 13, 2025, Pioneer Development signature and date lines blank. Section 2.1: vesting applies “Upon commencement of the Project within three (3) years of the Effective Date.” Section 2.2: “Section 10-4-10 of the UDO is reserved for additional regulations applicable to Energy Industrial Uses. No new or amended standards, code provisions, or special regulations for Energy Industrial Uses shall apply to the Subject Property during the twenty (20) year vested term from the Effective Date of this Agreement, unless Developer agrees in writing or to the extent required by state or federal law.” No reference to Ordinance 2025-53. Section 2.14: “seventy-eight (78) feet, inclusive of any rooftop mechanical equipment or appurtenances.” Section 3.5: water obligations “addressed exclusively in the Utility Agreement.” https://www.yorkville.il.us/DocumentCenter/View/13587/Ordinance-2025-77—record?bidId= (archived: https://web.archive.org/web/20261025151237/https://www.yorkville.il.us/DocumentCenter/View/13587/Ordinance-2025-77—record?bidId=). Annexation agreement, Ordinance No. 2025-78: https://www.yorkville.il.us/DocumentCenter/View/13588/Ordinance-2025-78—record?bidId= (archived: https://web.archive.org/web/20261025151421/https://www.yorkville.il.us/DocumentCenter/View/13588/Ordinance-2025-78—record?bidId=). Packet version: City Council Packet, November 10, 2025 (ArchiveCenter Item 6499), Planned Unit Development Agreement between the United City of Yorkville and Pioneer Development, LLC (Project Cardinal), packet pp. 272 to 290. Section 2.1: entitlements “fully vested and protected from amendments and changes to City ordinances, codes, or regulations for a period of twenty (20) years from the Effective Date.” Section 2.2: “No new or amended standards, code provisions, or special regulations for Energy Industrial Uses shall apply to the Subject Property during the twenty (20) year vested term from the Effective Date of this Agreement, unless Developer agrees in writing or to the extent required by state or federal law.” Section 2.3: approximately ten-year build-out; Phasing Plan “advisory only and non-binding.” Section 2.4: “All data center buildings shall be at least five hundred feet (500′) from the nearest residential or commercial structure outside the boundaries of the Subject Property,” measured “from existing, occupied, residential or commercial buildings as of the date of PUD approval.” Section 2.10: 100-foot Transition Zone Type D buffer with a 12-foot berm facing residential properties and 8 feet elsewhere; “No additional berms or landscape requirements shall be imposed unless Developer agrees in writing.” Section 2.11: “the most appropriate location for Mechanical Equipment is on the rooftops; therefore, whenever practical, mechanical equipment shall be placed on the rooftops”; project subject to the City Noise Ordinance “as it existed when the PUD application was approved by the City Council.” Section 2.14: 78-foot maximum height including rooftop equipment. Section 2.17: “all primary power used for the data center campus on the Subject Property will be delivered from the Commonwealth Edison power grid” unless the City Council approves otherwise. Section 3.4: continuous noise monitoring devices at the onset of each construction phase, a preliminary report within 60 days after each building is operational, devices maintained for the life of the project. Section 3.11: operational testing of generators “during the hours of 11:00 a.m. to 5:00 p.m., Monday through Friday, and not on any Holidays.” https://www.yorkville.il.us/ArchiveCenter/ViewFile/Item/6499 (archived: https://web.archive.org/web/20261025154939/https://www.yorkville.il.us/ArchiveCenter/ViewFile/Item/6499)
[15a] U.S. EPA, “Designation of Perfluorooctanoic Acid (PFOA) and Perfluorooctanesulfonic Acid (PFOS) as CERCLA Hazardous Substances,” Final Rule, effective July 8, 2024. MCLs for PFOA and PFOS set at 4.0 parts per trillion under the concurrent PFAS National Primary Drinking Water Regulation (April 10, 2024). https://www.epa.gov/superfund/designation-perfluorooctanoic-acid-pfoa-and-perfluorooctanesulfonic-acid-pfos-cercla (archived: https://web.archive.org/web/20261002070559/https://www.epa.gov/superfund/designation-perfluorooctanoic-acid-pfoa-and-perfluorooctanesulfonic-acid-pfos-cercla)
[15b] Pillsbury Winthrop Shaw Pittman LLP, PFAS Observer, “PFAS, HFCs and Related Chemicals in the Data Center Industry,” May 2, 2025 (cross-posted on Gravel2Gavel). “Historically, dry pipe fire suppression systems have used Class B aqueous film-forming foams (AFFF)”; activation “may result in the sudden discharge of large quantities of PFAS-containing AFFF.” https://pfas.pillsburylaw.com/pfas-hfcs-chemicals-data-center-industry/ (archived: https://web.archive.org/web/20261025155111/https://pfas.pillsburylaw.com/pfas-hfcs-chemicals-data-center-industry/)
[15c] U.S. EPA, Office of Emergency Management, “The SPCC Rule and Recent Amendments,” November 2010 (SPCC basics). Applicability to facilities storing more than 1,320 gallons of oil aboveground with a reasonable expectation of a discharge to navigable waters; secondary containment under 40 CFR 112.7(c) sized to “the typical failure mode, and the most likely quantity of oil that would be discharged”; qualified-facility self-certification available at “10,000 U.S. gallons or less in aggregate aboveground oil storage capacity,” with Professional Engineer certification otherwise. https://www.epa.gov/sites/default/files/2014-05/documents/spcc_basics.pdf (archived: https://web.archive.org/web/20260219022141/https://www.epa.gov/sites/default/files/2014-05/documents/spcc_basics.pdf). Rule text: 40 CFR Part 112.
[15d] U.S. EPA, “Rescission of Regulatory Determinations and Removal of Related Provisions for Four PFAS Substances,” proposed rule, 91 FR 29413, May 20, 2026, FR Doc. 2026-10085, docket EPA-HQ-OW-2025-0654: would rescind the determinations for PFHxS, PFNA, HFPO-DA, and “mixtures of these three PFAS plus perfluorobutane sulfonic acid (PFBS)”; “This action does not impact the MCLGs, MCLs or the regulatory provisions” for PFOA and PFOS. https://www.federalregister.gov/documents/2026/05/20/2026-10085/rescission-of-regulatory-determinations-and-removal-of-related-provisions-for-four-pfas-substances (archived: https://web.archive.org/web/20261016032522/https://www.federalregister.gov/documents/2026/05/20/2026-10085/rescission-of-regulatory-determinations-and-removal-of-related-provisions-for-four-pfas-substances). U.S. EPA, “Extending the Compliance Deadline for the PFOA and PFOS Maximum Contaminant Levels,” proposed rule, 91 FR 29425, May 20, 2026, FR Doc. 2026-10086, docket EPA-HQ-OW-2025-1742: compliance moved “from April 26, 2029, to April 26, 2031” for systems that submit a request, through a federal exemption under SDWA section 1416(f). https://www.federalregister.gov/documents/2026/05/20/2026-10086/extending-the-compliance-deadline-for-the-pfoa-and-pfos-maximum-contaminant-levels (archived: https://web.archive.org/web/20261007222507/https://www.federalregister.gov/documents/2026/05/20/2026-10086/extending-the-compliance-deadline-for-the-pfoa-and-pfos-maximum-contaminant-levels). EPA proposal page, MCLs “remain 4.0 parts per trillion (ppt) each”: https://www.epa.gov/sdwa/proposed-pfoa-and-pfos-compliance-extension-rule (archived: https://web.archive.org/web/20261016195758/https://www.epa.gov/sdwa/proposed-pfoa-and-pfos-compliance-extension-rule). Comment periods closed July 20, 2026; no final action found as of October 24, 2026.
[16] Uptime Institute, “Annual Outage Analysis 2025,” May 6, 2025. https://uptimeinstitute.com/about-ui/press-releases/uptime-announces-annual-outage-analysis-report-2025 (archived: https://web.archive.org/web/20260701002954/https://uptimeinstitute.com/about-ui/press-releases/uptime-announces-annual-outage-analysis-report-2025)
[16a] NFPA, “NFPA 855, Standard for the Installation of Stationary Energy Storage Systems.” Becomes legally enforceable when adopted by the applicable state or local authority having jurisdiction, as with other NFPA standards. UL, “UL 9540A Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems,” a test method used to characterize fire propagation risk rather than a standalone regulatory requirement; UL 9540 is the separate product safety standard for energy storage systems. https://www.nfpa.org/codes-and-standards/nfpa-855-standard-development/855 (archived: https://web.archive.org/web/20261017191038/https://www.nfpa.org/codes-and-standards/nfpa-855-standard-development/855) and https://www.ul.com/services/ul-9540a-test-method (archived: https://web.archive.org/web/20261025155719/https://www.ul.com/services/ul-9540a-test-method)