Part 2 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.
If one environmental claim about data centers has traveled farther than any other, it is Northern Virginia’s diesel generators. Loudoun County holds nearly half of the more than 13,500 diesel backup engines in Virginia data center air permit applications, inside an ozone nonattainment area, and that fact shows up at Illinois hearings as if the engines came with the building. [3][4d]
Some of it does come with the building. Some of it is specific to Virginia. And one piece, the possibility that a grid operator directs every backup fleet in its territory to start at once, moved in 2026 from a hypothetical to a federal authorization that reaches ComEd’s territory as directly as it reaches Loudoun’s. This post sorts six generator claims: the Virginia record, the nonattainment baseline that does not transfer, the engine counts in four Illinois EPA permit files that do, the emergency-order question nobody in the Yorkville record asked, the “uniquely dirty” claim, and the xAI turbine allegations that get cited as if they described the industry.
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.
Air Quality: Diesel Generators
Claim: Data center generators are degrading air quality in Northern Virginia. Tier: Regional.
True in that place, for reasons specific to that place. The problem is not Virginia’s grid, which runs below the national NOx average at 0.282 lbs per MWh. [1] It is the concentration of diesel backup generators in Loudoun County, which holds nearly half of the more than 13,500 covered by Virginia data center air permit applications as of September 2026, inside an area designated nonattainment under the 2015 ozone National Ambient Air Quality Standards (NAAQS). [3][4d] Published counts vary with date and method: December 2025 reporting put the state at about 9,000, and a Washington Post analysis of permits through 2024 put it at 10,500. [4a][4e]
Virginia’s Joint Legislative Audit and Review Commission (JLARC) found in its December 2024 study that generators make up less than 4% of Northern Virginia’s regional NOx emissions. It separately reported that actual 2023 emissions were 7% of what permits allowed, and that most generator emissions come from maintenance testing. It concluded generator emissions are unlikely to adversely affect regional air quality, and in the same passage said local effects are a different question: the industry’s generator clusters have no parallel in other development, their intermittent use makes them difficult to model, and regional monitoring does not capture localized effects. [4] Permits are issued and capped per site, so each campus is evaluated on its own fleet rather than as part of a cluster drawing on a shared airshed, the volume of air a region’s sources all emit into and all breathe from. Almost one-third (29%) of operational data center properties in Virginia sit within 200 feet of residentially zoned land. [4][4c]
The legitimate concern lives in the gap between “less than 4% of regional NOx” and an outage nobody has modeled. JLARC sized the worst case, every Northern Virginia data center at its maximum allowed emissions as a prolonged multi-county outage could cause within a few days, at over 9,000 tons of NOx, about half of what all sources in Northern Virginia typically emit in a year, and did not model its effect on air quality. [4] Scheduled testing runs unit by unit. A regional outage is the case in which simultaneous activation becomes plausible, and I found no published model of it.
A single-facility version has already happened. Vantage’s VA2 campus in Sterling ran its backup generators for almost 24 hours on July 16 and 17, 2026, after a power failure, while the region was already under degraded air quality from Canadian wildfire smoke. A neighbor reported a 60-decibel reading at his property line, by a method the report does not describe, against Loudoun County’s 55-decibel nighttime limit. Virginia DEQ Director Michael Rolband told him the agency lacks “regulatory authority to stop these actions undertaken in response to the emergency.” [4b] That is the rule working as written: federal standards put no hour limit on emergency operation. [5] DEQ has since put up its first five sensors in eastern Loudoun, measuring fine particulate, carbon monoxide, and nitrogen dioxide from March 2026, the start of a three-year study to measure generator effects directly. [19][4]
Claim: What happened in Loudoun County will happen here. Tier: Misattributed.
The nonattainment baseline does not transfer. DeKalb County is designated attainment/unclassifiable for the 2015 ozone standard and for the annual and 24-hour fine particulate standards. [5a] Kendall County is only partly in the Chicago, IL-IN-WI nonattainment area for the 2015 ozone standard, and the part is Oswego Township; the area was reclassified Serious effective January 16, 2025. [5a] At that classification a new source counts as major at 50 tons per year of NOx or volatile organic compounds rather than 100, with a volatile organic compound offset ratio of at least 1.2 to 1. [5a][5b] A generator yard in Oswego Township is permitted under those thresholds; the same yard elsewhere in Kendall County is not.
The engines would also be cleaner. The federal rules are the same in both states: New Source Performance Standards under 40 CFR Part 60 Subpart IIII set criteria-pollutant limits at manufacture, RICE NESHAP under 40 CFR Part 63 Subpart ZZZZ governs hazardous air pollutants, testing is capped at 100 hours a year with up to 50 for other non-emergency use, and emergency operation has no limit. [5] Illinois has gone further. Public Act 104-0458, effective June 1, 2026, applies to data centers whose generators need a federally enforceable state operating permit or a Title V permit. For construction permits applied for from December 2026, it requires each diesel backup generator to meet standards “at least as protective as Tier 4” for nonroad diesel engines and to run as an emergency or standby unit only; gas generators must meet Tier 2 for large spark-ignition engines. A generator that falls out of Tier 4 compliance during a power outage may run up to 24 sequential hours without violating the permit. [5c] A Tier 2 engine with add-on controls can qualify as equivalent, and existing generators are untouched. [5c] Smaller campuses permitted below those thresholds are outside the requirement. Virginia had one Tier 4 data center when JLARC counted. [4] Project Cardinal’s developer told Yorkville’s council in March 2026 it would go past the statute: particulate filters, selective catalytic reduction, and oxidation catalysts on every generator, renewable diesel as fuel, and testing only between 11 a.m. and 5 p.m. on non-holiday weekdays. [11v]
How often they would run is a promise, not a measurement. Cardinal’s representative testified in July 2025 that testing “is only going to occur once or twice a year” and that generators at campuses like this “are really never used outside of testing.” [11y] The federal ceiling is 100 hours. I found no dataset of typical testing hours at compliant data centers, and the continuous monitors Yorkville required are the only instrument on the record that will produce one.
Proximity does transfer, as a fact about the corridor rather than an import. Yorkville’s planning staff built the Virginia measure for the Eldamain corridor in May 2025: of twelve data center projects approved, under review, or in site inquiry, four sat within 200 feet of a residential property line, two of them immediately adjacent. [11w]
Claim: In a grid emergency, every data center’s generators will run at once. Tier: Contested. Authorized nine times in 2026, used none.
This is the part of the Virginia concern that does transfer, and it has moved from hypothetical to authorized. In 2026 the Department of Energy issued Federal Power Act section 202(c) emergency orders, nine by PJM’s count, letting PJM, the grid operator for Northern Virginia and for ComEd’s territory in Northern Illinois, direct backup generation at data centers and other large loads as a last resort before or during a level 3 Energy Emergency Alert, the stage at which firm load may be shed. Each order covers one emergency, from a few days to four weeks. [5e][5d][5h][5i] PJM asked that the generators be allowed to run “notwithstanding any applicable environmental limitations”; the orders instead require operation consistent with environmental law “to the maximum extent practicable.” [5f][5h] When an order is in effect, it reaches every ComEd-served proposal in DeKalb and Kendall County, and the hours it would be used are the grid’s most stressed, which in summer is also ozone-forming weather. That timing point is my reasoning from how the orders are triggered, not a finding in them.
PJM has not used the authority. David Souder, PJM’s executive director of system operations, wrote on October 15 that “PJM did not use that authority and has not done so to date.” [5i] That is why this is Contested rather than Regional: authorized nine times, used none.
The Yorkville record shows the gap. Cardinal’s developer told the council in March 2026 that no backup generator dispatch other than testing is permitted under its PUD agreement. [11v] Eight months earlier its representative had described the other case under oath: “if it’s curtailed in an emergency, we would be curtailed first and we would have backup generators.” [11y] The agreement’s freeze on new city standards yields “to the extent required by state or federal law.” [11x] Whether a city agreement can keep generators off when PJM directs them on under a federal order is a question nobody in the Yorkville record asked.
Claim: Data center generators are uniquely dirty. Tier: Selective. The rule is shared; the engine count is not.
The same federal emergency-engine rules govern backup generators at hospitals, water and wastewater plants, and other critical facilities. [5] (The DOE emergency orders run the other way: they exclude hospitals, 911 centers, and similar facilities from the generators PJM may direct. [5d]) What differs at a data center campus is the number of engines on one site, and the engine count is the number to compare. Illinois has it, campus by campus, in Illinois EPA’s permit files.
Quick Compare: diesel generators in four Illinois EPA air records
| Campus | Record | Engines | Capacity | Hour limit |
|---|---|---|---|---|
| CyrusOne, Aurora | Draft Title V permit, March 2026 | 91 | about 211 MW | Not stated in summary read |
| Microsoft, Hoffman Estates | Construction permit, December 2024 | 34 | about 100 MW | 1,984 hours combined for the 32 large units |
| Prime, Elk Grove Village | Construction permit, July 2025 | 39 | about 127 MW | 35 hours per engine |
| Stream, Elk Grove Village | Application, January 2026 | 126 | 315 MW | Pending |
Source: [5j]. Capacity is the sum of the listed engine ratings.
Those four come to 290 engines and about 753 MW, all in the suburbs. [5j] The issued permits also cap testing well under the federal 100 hours. Annual attainment also does not settle short-term exposure. Diesel exhaust carries fine and ultrafine particulate, black carbon, and hazardous air pollutants; EPA sets a 1-hour NO2 standard and a 24-hour fine particulate standard alongside the annual ones, and the hazardous air pollutants in diesel exhaust have no ambient standard. What a resident 200 feet from a generator yard breathes during a testing cycle or a multi-hour outage depends on engine tier, aftertreatment, stack height, and dispersion. Illinois EPA’s modeling memoranda carry that analysis for some suburban campuses. For Prime, the applicant’s consultant ran a cumulative 1-hour NO2 model of the area, including nearby sources and background, that found modeled exceedances of the standard, and Illinois EPA’s modeling unit confirmed Prime’s own maximum contribution at those points at 0.16 micrograms per cubic meter against a 7.52 significance level. [5j] I found no such filing for any DeKalb or Kendall proposal.
Claim: Data centers run unpermitted power plants. Tier: Isolated.
xAI is the case behind this claim, and the allegations describe operator conduct, not the building type. According to the Southern Environmental Law Center, xAI installed as many as 35 gas turbines at its Colossus 1 facility in Memphis without air permits after announcing it in June 2024, then removed the unpermitted units after a June 2025 notice of intent to sue, and the Shelby County Health Department permitted 15 on July 2, 2025, on the position that the earlier units were exempt nonroad engines, which SELC disputes. [6a] At its Southaven, Mississippi site, the NAACP’s April 2026 Clean Air Act suit alleges unpermitted turbines that could emit more than 1,700 tons of NOx a year, and the plaintiffs counted 57 on site by June 2026 against Mississippi DEQ’s position that temporary units need no permit. [6b][6c] No court or agency has issued a final finding. The Memphis area was nonattainment for the 2008 ozone standard until EPA redesignated it in 2016 under a maintenance plan running through 2027. [6d] The alleged pattern is operating unpermitted combustion equipment, removing it under legal threat, and repeating the approach across a state line. Whether that was deliberate is what the litigation will decide.
What to ask for. Require the applicant to state the generator count, engine tier and aftertreatment, fuel storage, stack heights, and expected testing hours, in the approval record rather than in testimony. Illinois’s Tier 4 rule reaches only campuses that need a federally enforceable state or Title V operating permit, for construction permits applied for from December 2026, so a smaller campus or an earlier application is outside it unless the agreement says otherwise. [5c] Ask for a cumulative estimate: the combined NOx contribution of every generator fleet already approved along the corridor, counted against the local airshed. Virginia issues and caps air permits site by site, and Loudoun County reached thousands of engines one permit at a time. [4][4d] And ask, in writing, how the campus will respond if PJM directs its backup generation to run under a DOE emergency order, and how it would respond if its utility disconnected it from grid power under one. A development agreement that limits generators to testing should say what happens when federal direction conflicts with it, because Cardinal’s freeze on city standards yields “to the extent required by state or federal law.” [5d][5f][11x]
What nobody knows. PJM says it has not directed any data center backup fleet to run under the 2026 orders. [5i] What nobody has measured is what a simultaneous start would do at the nearest monitor. The first time PJM uses the authority, its notice to DOE and the run hours will be the record to request, and the monitor data for those hours will turn the question from a model into a measurement. [5h]
This is part 2 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: the grid. Next: water supply, where the numbers in Yorkville changed by a factor of eight and the record does not say why.
Cover photo: Rsparks3 / Wikimedia Commons, CC0
Citations
[1] U.S. EPA, eGRID 2023 Summary Tables, initial release January 15, 2025; rev2 released June 12, 2025 (summary tables PDF internal production date March 27, 2025). https://www.epa.gov/system/files/documents/2025-06/summary_tables_rev2.pdf (archived: https://web.archive.org/web/20261025155941/https://www.epa.gov/system/files/documents/2025-06/summary_tables_rev2.pdf). Three-decimal subregion output emission rates (Annual NOx and SO2, lb/MWh) as published on EPA’s eGRID Summary Data page, “eGRID with 2023 Data”: https://www.epa.gov/egrid/summary-data (archived: https://web.archive.org/web/20261017013542/https://www.epa.gov/egrid/summary-data). Table 4, “State Resource Mix (eGRID2023),” Illinois: total net generation 177,690,287 MWh; nuclear 54.9%, gas 16.0%, coal 15.3%, wind 12.3%, solar 1.1%.
[3] Virginia Administrative Code 9VAC5-20-204, Nonattainment areas. https://law.lis.virginia.gov/admincode/title9/agency5/chapter20/section204/ (archived: https://web.archive.org/web/20260904211934/https://law.lis.virginia.gov/admincode/title9/agency5/chapter20/section204/). Federal designation: 40 CFR 81.347, Virginia, 2015 8-Hour Ozone NAAQS, “Washington, DC-MD-VA” Nonattainment, classification Moderate dated 11/7/2022, including Loudoun, Fairfax, Prince William, and Arlington counties. https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-81/subpart-C/section-81.347 (archived: https://web.archive.org/web/20250215131738/https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-81/subpart-C/section-81.347). Official annual edition, 40 CFR 81.347 (July 1, 2025): https://www.govinfo.gov/content/pkg/CFR-2025-title40-vol20/pdf/CFR-2025-title40-vol20-sec81-347.pdf (archived: https://web.archive.org/web/20261025190935/https://www.govinfo.gov/content/pkg/CFR-2025-title40-vol20/pdf/CFR-2025-title40-vol20-sec81-347.pdf)
[4] Joint Legislative Audit and Review Commission, “Data Centers in Virginia,” Report 598 (House/Senate Document RD206), December 9, 2024. Summary findings: generators “make up less than 4 percent of regional emissions of nitrogen oxides” in Northern Virginia (p. vi); “One-third of data centers are currently located near residential areas” (p. vii); “a large majority of data centers do not generate noise complaints because of their location or design” (p. viii). Chapter 5: 2023 actual emissions “only 7 percent of what permits allowed, with most emissions coming from maintenance testing”; emissions “unlikely to adversely affect regional air quality”; generators’ “intermittent use makes their impacts difficult to model”; regional monitoring “does not effectively capture localized effects”; DEQ three-year monitoring study (p. 59). “General Assembly could incentivize use of generators with lower emission rates”; Tier 4 engines or SCR reduce nitrogen oxides and particulate matter “reportedly by up to 90 percent”; “only one uses Tier 4 generators” (p. 60). Permits “issued per data center site, rather than per building or generator”; worst case “where all data centers in Northern Virginia reach their maximum allowed emissions” would emit “over 9,000 tons of nitrogen oxides in the region,” “about half of what has typically been emitted annually in Northern Virginia by all sources” (p. 60). Chapter 6: noise “is not loud enough to damage nearby residents’ hearing and rarely loud enough to violate noise ordinances”; audibility past the property line “depends on its design and its type of cooling system”; complaint noise “ranges from an estimated 40 to 59 decibels” (p. 75). “Almost one-third (29 percent) of operational data center properties in Virginia are within 200 feet of residentially zoned properties” (p. 77; Table B-1, p. 103). https://jlarc.virginia.gov/pdfs/reports/Rpt598.pdf (archived: https://web.archive.org/web/20261025155822/https://jlarc.virginia.gov/pdfs/reports/Rpt598.pdf). Legislative repository copy: https://rga.lis.virginia.gov/Published/2025/RD206 (archived: https://web.archive.org/web/20260908164522/https://rga.lis.virginia.gov/Published/2025/RD206)
[4a] Charles Paullin, Inside Climate News, “Virginia Regulators Weigh Expanded Use of Data Centers’ Polluting Generators,” republished by Virginia Mercury (December 16, 2025) and VPM (December 17, 2025). Reports “about 9,000 generators in Virginia, with about 4,700 in Loudoun County” without naming a source for the count; Julie Bolthouse, director of land use for the Piedmont Environmental Council, on Tier II share [advocacy source]; reports the JLARC worst-case figure now cited directly to [4], p. 60. https://virginiamercury.com/2025/12/16/virginia-regulators-weigh-expanded-use-of-data-centers-polluting-generators/ (archived: https://web.archive.org/web/20260824143656/https://virginiamercury.com/2025/12/16/virginia-regulators-weigh-expanded-use-of-data-centers-polluting-generators/)
[4b] Debbie Williams, Northern Virginia Magazine, “Sterling Resident Says Data Center’s Generators Produced Excessive Noise, Pollution,” July 21, 2026. Vantage VA2, Sterling: backup generators ran “almost 24 hours” on July 16 to 17, 2026, after a power failure, during regional wildfire-smoke air quality degradation; resident measurement of 60 decibels at the property line against Loudoun County’s 55-decibel nighttime limit; Virginia DEQ Director Michael Rolband’s reply that DEQ lacks “regulatory authority to stop these actions undertaken in response to the emergency.” https://northernvirginiamag.com/news/2026/07/21/sterling-resident-says-data-centers-generators-produced-excessive-noise-pollution/ (archived: https://web.archive.org/web/20261005093042/https://northernvirginiamag.com/news/2026/07/21/sterling-resident-says-data-centers-generators-produced-excessive-noise-pollution/)
[4c] James Jarvis, FFXnow, “Report: Fairfax County leads state in data centers near residential neighborhoods,” December 11, 2024. Reporting JLARC’s December 9, 2024 findings: nearly a third of Virginia’s data centers are within 200 feet of residential areas; county figures measured against residential zones (Fairfax 55% of 20 within 200 feet; Loudoun 24% of 71 within 200 feet and 34% within 500 feet). https://www.ffxnow.com/2024/12/11/report-fairfax-county-leads-state-in-data-centers-near-residential-neighborhoods/ (archived: https://web.archive.org/web/20261025155019/https://www.ffxnow.com/2024/12/11/report-fairfax-county-leads-state-in-data-centers-near-residential-neighborhoods/)
[4d] Kaela Roeder, Technical.ly, “Mapped: Data center permits show Northern Virginia generator concentration,” September 16, 2026. Analysis of 195 air permit applications: “more than 13,500 backup generators” at Virginia data centers, nearly half of them in Loudoun County. https://technical.ly/entrepreneurship/mapped-virginia-data-centers-thousands-of-backup-generators/ (archived: https://web.archive.org/web/20261025154833/https://technical.ly/entrepreneurship/mapped-virginia-data-centers-thousands-of-backup-generators/)
[4e] The Washington Post, “As data centers boom, Virginians breathe the exhaust of 10,000 diesel generators,” May 28, 2026. Analysis of state air permits and reported emissions for 132 Northern Virginia data centers through the end of 2024: 10,500 generators attached to data centers in Virginia. (Paywalled; figures confirmed through an excerpt.) https://www.washingtonpost.com/business/2026/05/28/data-centers-boom-virginians-breathe-exhaust-10000-diesel-generators/ (archived: https://web.archive.org/web/20260528194541/https://www.washingtonpost.com/business/2026/05/28/data-centers-boom-virginians-breathe-exhaust-10000-diesel-generators/)
[5] 40 CFR Part 60 Subpart IIII, Standards of Performance for Stationary Compression Ignition Internal Combustion Engines (criteria pollutant limits including NOx, applies at manufacture). Emergency engine hours at 40 CFR 60.4211(f): no time limit during emergencies (f)(1); up to 100 hours per calendar year for maintenance checks and readiness testing (f)(2); up to 50 hours per calendar year of non-emergency operation, counted toward the 100, with peak shaving and grid power sales prohibited except under the local-reliability dispatch conditions in (f)(3)(i). eCFR, https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-60/subpart-IIII/subject-group-ECFR7cc160b57a360ac/section-60.4211 (archived: https://web.archive.org/web/20260617111210/https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-60/subpart-IIII/subject-group-ECFR7cc160b57a360ac/section-60.4211). 40 CFR Part 63 Subpart ZZZZ, National Emissions Standards for Hazardous Air Pollutants for Stationary Reciprocating Internal Combustion Engines (RICE NESHAP), parallel emergency engine provisions at 40 CFR 63.6640(f). eCFR, https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-63/subpart-ZZZZ (archived: https://web.archive.org/web/20260713101544/https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-63/subpart-ZZZZ)
[5a] 40 CFR 81.314, Illinois designations, via eCFR (current as read October 23, 2026). 2015 8-Hour Ozone NAAQS: “Chicago, IL-IN-WI,” Nonattainment, classification Serious dated 1/16/2025, including “Kendall County (part): Oswego Township”; De Kalb County “Attainment/Unclassifiable.” DeKalb County “Unclassifiable/Attainment” for the 2012 Annual PM2.5 and 2006 24-Hour PM2.5 NAAQS and for NO2 (2010 1-Hour Standard). https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-81/subpart-C/section-81.314 (archived: https://web.archive.org/web/20261025162744/https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-81/subpart-C/section-81.314). Also U.S. EPA, Green Book, Illinois Nonattainment/Maintenance Status for Each County by Year for All Criteria Pollutants: https://www3.epa.gov/airquality/greenbook/anayo_il.html (archived: https://web.archive.org/web/20260825123608/https://www3.epa.gov/airquality/greenbook/anayo_il.html)
[5b] 40 CFR 51.165 (Nonattainment New Source Review) and 40 CFR 52.21 (Prevention of Significant Deterioration); Clean Air Act Section 182, 42 U.S.C. 7511a. PSD major source thresholds in attainment/unclassifiable areas are generally 100 to 250 tons per year depending on source category. Nonattainment NSR thresholds vary by pollutant and nonattainment classification and can run as low as 50, 25, or 10 tons per year for ozone precursors in more severe classifications. 40 CFR 51.165(a)(1)(iv)(A): major stationary source thresholds of “50 tons per year or more of nitrogen oxides in any serious nonattainment area for ozone” and “50 tons per year of Volatile organic compounds in any serious ozone nonattainment area”; 51.165(a)(9)(ii)(C): VOC offset ratio of at least 1.2:1 in any serious nonattainment area for ozone. https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-51/subpart-I/section-51.165 (archived: https://web.archive.org/web/20260614073844/https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-51/subpart-I/section-51.165). Both regimes aggregate emissions units under common control on contiguous or adjacent property as a single stationary source. https://www.epa.gov/nsr (archived: https://web.archive.org/web/20261025155400/https://www.epa.gov/nsr) and https://www.law.cornell.edu/uscode/text/42/7511a (archived: https://web.archive.org/web/20260615152932/https://www.law.cornell.edu/uscode/text/42/7511a) and https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-52/subpart-A/section-52.21 (archived: https://web.archive.org/web/20260712090245/https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-52/subpart-A/section-52.21)
[5c] Illinois Public Act 104-0458 (SB 25, 104th General Assembly), approved January 8, 2026, effective June 1, 2026, amending Section 39(a) of the Environmental Protection Act, 415 ILCS 5/39(a): each air pollution construction permit for diesel powered backup generators at a data center (as defined in 20 ILCS 605/605-1025(c)) “that is applied for 6 months after the effective date” and that requires a federally enforceable State operating permit or a Clean Air Act Permit Program permit shall require each backup generator to “meet standards at least as protective as Tier 4 standards for non-road diesel engines set out by the United States Environmental Protection Agency in 40 CFR 1039” and “operate solely as an emergency or standby unit in accordance with 35 Ill. Adm. Code 211.1920”; up to 24 sequential hours of operation after falling out of Tier 4 compliance during a power outage “shall not be considered a violation of the permit”; natural gas backup generators must meet Tier 2 standards for non-road large spark-ignition engines (40 CFR 1048). https://www.ilga.gov/documents/legislation/PublicActs/104/104-0458.htm (archived: https://web.archive.org/web/20261025155635/https://www.ilga.gov/documents/legislation/PublicActs/104/104-0458.htm) and bill status https://www.ilga.gov/Legislation/BillStatus?DocNum=25&GAID=18&DocTypeID=SB&SessionID=114 (archived: https://web.archive.org/web/20261025162320/https://www.ilga.gov/Legislation/BillStatus?DocNum=25&GAID=18&DocTypeID=SB&SessionID=114). Interpretation that Tier 4 equivalence can be met with add-on controls on Tier 2 or Tier 3 engines and that existing generators are unaffected: ALL4 Inc. (environmental permitting consultancy), “Illinois Data Centers: Fears for Tiers,” June 11, 2026. https://www.all4inc.com/4-the-record-articles/illinois-data-centers-fears-for-tiers/ (archived: https://web.archive.org/web/20261025152142/https://www.all4inc.com/4-the-record-articles/illinois-data-centers-fears-for-tiers/)
[5d] U.S. Department of Energy, Emergency Order No. 202-26-23 (Federal Power Act section 202(c)), issued May 18, 2026, effective May 18 through May 20, 2026: PJM “is authorized to direct backup generation resources at data centers” and other large load sites “as a last resort before declaring an Energy Emergency Alert (EEA) 3” or during an EEA 3; excluded facilities (defense, homeland security, first responder, air traffic control, hospitals, 911); PJM sets the times and parameters; resources “must otherwise comply with ancillary environmental requirements, including, but not limited to, monitoring, reporting, and recordkeeping requirements, to the maximum extent feasible”; PJM to notify DOE within one day of directing resources. DOE order page summary: “PJM is authorized to call upon its Transmission Owners and Electric Distribution Companies to implement this order as needed.” https://www.energy.gov/documents/doe-emergency-order-no-202-26-23pdf (archived: https://web.archive.org/web/20261025160019/https://www.energy.gov/documents/doe-emergency-order-no-202-26-23pdf). Order page: https://www.energy.gov/ceser/federal-power-act-section-202c-pjm-interconnection-llc-pjm-order-no-202-26-23 (archived: https://web.archive.org/web/20260706213120/https://www.energy.gov/ceser/federal-power-act-section-202c-pjm-interconnection-llc-pjm-order-no-202-26-23)
[5e] U.S. Department of Energy, “Federal Power Act Section 202(c): PJM Interconnection (PJM) Order No. 202-26-06,” order issued January 26, 2026, expiring January 31, 2026, authorizing PJM “to direct backup generation resources at data centers” as a last resort before or during an EEA 3; Order No. 202-26-06A issued January 29, 2026, extending the authorization through February 2, 2026; rehearing order 202-26-06B, February 4, 2026. https://www.energy.gov/ceser/federal-power-act-section-202c-pjm-interconnection-pjm-order-no-202-26-06 (archived: https://web.archive.org/web/20260810062617/https://www.energy.gov/ceser/federal-power-act-section-202c-pjm-interconnection-pjm-order-no-202-26-06). Order PDFs: https://www.energy.gov/documents/doe-order-no-202-26-06-pjm (archived: https://web.archive.org/web/20260706212823/https://www.energy.gov/documents/doe-order-no-202-26-06-pjm) and https://www.energy.gov/documents/order-no-202-26-06-pjm-backup-generators (archived: https://web.archive.org/web/20260706212824/https://www.energy.gov/documents/order-no-202-26-06-pjm-backup-generators)
[5f] PJM Interconnection, applications to the Secretary of Energy for section 202(c) orders. January 26, 2026 application: load forecast of about 138,000 MW for the Monday evening peak and 147,000 MW for the Tuesday morning peak; request that the order allow backup generation use “notwithstanding any applicable environmental limitations under federal or state law.” https://www.energy.gov/documents/pjm-application-202c-backup-generators (archived: https://web.archive.org/web/20261024150830/https://www.energy.gov/documents/pjm-application-202c-backup-generators). May 17, 2026 application: request that the order allow use “notwithstanding any applicable environmental limitations under federal, state, or local law or regulation” and “expressly allow” utilities “to disconnect the data centers from utility source power to automatically transfer them to back up generation.” https://www.energy.gov/documents/pjms-202c-backup-gen-application-202-26-23 (archived: https://web.archive.org/web/20260706213119/https://www.energy.gov/documents/pjms-202c-backup-gen-application-202-26-23). October 11, 2026 application: demand forecast “at or around 111,500 MW (or higher) on October 13” against generation outages “anticipated to reach around 61,591 MW”; same environmental-limitations request. https://www.pjm.com/-/media/DotCom/documents/other-fed-state/20261011-request-for-general-unit-operation-and-emergency-backup-section-202c.pdf (archived: https://web.archive.org/web/20261016132413/https://www.pjm.com/-/media/DotCom/documents/other-fed-state/20261011-request-for-general-unit-operation-and-emergency-backup-section-202c.pdf)
[5h] U.S. Department of Energy, “Federal Power Act Section 202(c): PJM Interconnection, L.L.C. (PJM) Order No. 202-26-50,” issued October 12, 2026 on PJM’s October 11 application, effective October 13 through October 16, 2026; directs dispatch of specified units and authorizes PJM to direct backup generation resources as a last resort before or during an EEA 3; paragraph E limits operation “to the times and within the parameters determined by PJM for maintaining grid reliability” and “consistent, to the maximum extent practicable, with any applicable environmental law,” and requires PJM to notify DOE daily of each Specified Resource and backup generation resource operated in reliance on the order. https://www.energy.gov/ceser/federal-power-act-section-202c-pjm-interconnection-llc-pjm-order-no-202-26-50 (archived: https://web.archive.org/web/20261025162313/https://www.energy.gov/ceser/federal-power-act-section-202c-pjm-interconnection-llc-pjm-order-no-202-26-50). Order PDF: https://www.energy.gov/documents/doe-order-no-202-26-50 (archived: https://web.archive.org/web/20261017134245/https://www.energy.gov/documents/doe-order-no-202-26-50). Intervening orders reported by Utility Dive (May 19, 2026, Ethan Howland, “PJM gets emergency approval to curtail data centers, large loads during hot weather,” https://www.utilitydive.com/news/pjm-doe-emergency-order-curtail-data-centers/820571/ (archived: https://web.archive.org/web/20260928161135/https://www.utilitydive.com/news/pjm-doe-emergency-order-curtail-data-centers/820571/)) and Gibson Dunn client alert, “DOE’s Emergency Order Signals New Role for Data Centers’ Backup Power,” May 21, 2026, https://www.gibsondunn.com/doe-emergency-order-signals-new-role-for-data-centers-backup-power/ (archived: https://web.archive.org/web/20260618203251/https://www.gibsondunn.com/doe-emergency-order-signals-new-role-for-data-centers-backup-power/)
[5i] PJM Interconnection, Inside Lines, David Souder, “Providing Reliable Electricity in a New Reality,” October 15, 2026: “The U.S. Department of Energy, for the ninth time this year, issued an order to allow PJM to direct backup generation at data centers and other Large Load electricity customers to operate to avoid outages to other customers”; “While PJM did not use that authority and has not done so to date, it remains a valuable tool to help protect regular customers.” https://insidelines.pjm.com/providing-reliable-electricity-in-a-new-reality/ (archived: https://web.archive.org/web/20261016154415/https://insidelines.pjm.com/providing-reliable-electricity-in-a-new-reality/). PJM, Inside Lines operations update, October 13, updated October 14, 2026: “PJM has not had to make use of Large Load backup generation to date.” https://insidelines.pjm.com/operations-update-extends-maximum-generation-alert-calls-on-demand-response/ (archived: https://web.archive.org/web/20261017134243/https://insidelines.pjm.com/operations-update-extends-maximum-generation-alert-calls-on-demand-response/). PJM daily compliance report under Order No. 202-26-50 for October 14 operations, dated October 15, 2026, listing six generating units and no backup generation: https://www.pjm.com/-/media/DotCom/documents/other-fed-state/20261015-pjm-daily-compliance-report-doe-order-no-202-26-50.pdf (archived: https://web.archive.org/web/20261025162436/https://www.pjm.com/-/media/DotCom/documents/other-fed-state/20261015-pjm-daily-compliance-report-doe-order-no-202-26-50.pdf). PJM Operating Committee, October 8, 2026, “202(c) Update in Preparation for Winter Season,” listing the prior backup generation orders (202-26-06/06A January 26; 202-26-23 May 18; 202-26-33/33A June 30 to July 7; 202-26-35 July 14 to 21; 202-26-40 August 21 to September 18; 202-26-41 September 1 to 8): https://www.pjm.com/-/media/DotCom/committees-groups/committees/oc/2026/20261008/20261008-item-13—202c-update-in-preparation-for-winter-season-presentation.pdf (archived: https://web.archive.org/web/20261012000035/https://www.pjm.com/-/media/DotCom/committees-groups/committees/oc/2026/20261008/20261008-item-13—202c-update-in-preparation-for-winter-season-presentation.pdf). Axios Richmond, Anna Spiegel and Karri Peifer, October 14, 2026: “Dominion confirmed Wednesday that none of the data centers it serves have been switched to backup generators because of the order or elevated grid conditions.” https://www.axios.com/local/richmond/2026/10/14/richmond-dominion-pjm-energy-emergency-order-blackouts (archived: https://web.archive.org/web/20261016211416/https://www.axios.com/local/richmond/2026/10/14/richmond-dominion-pjm-energy-emergency-order-blackouts)
[5j] Illinois EPA, Bureau of Air permit records, read October 24, 2026. CyrusOne LLC, 2905 E. Diehl Road, Aurora: Preliminary Draft CAAPP (Title V) Permit No. 17060002, dated March 17, 2026, “Purpose of Application: Issue New Permit to a New Major Source”; Condition 4.1.1 lists 91 diesel-fired emergency generators (6 x 2,500 kW; 8 x 2,750 kW; 8 x 2,500 kW; 4 x 2,250 kW; 28 x 2,250 kW; 36 x 2,250 kW; 1 x 1,250 kW); Condition 8.1(a) NOx 97.96 tons/year. https://webapps.illinois.gov/EPA/WebSiteApi/api/PublicNotices/GetAirPermitDocument/10253 (archived: https://web.archive.org/web/20261025160122/https://webapps.illinois.gov/EPA/WebSiteApi/api/PublicNotices/GetAirPermitDocument/10253). Hoffman Estates (CHI06 and CHI07) Data Center, 2045 Lakewood Boulevard, Hoffman Estates: construction permit, Application No. 23110003, issued December 19, 2024; 32 x 4,376 BHP (3,100 ekW) and 2 x 762 BHP (500 ekW) diesel generators; large units’ runtime “shall not exceed 1984 hours/year (combined),” NOx 38.85 tons/year. https://epa.illinois.gov/content/dam/soi/en/web/epa/topics/environmental-justice/documents/ira/ira-analyses/23110003.pdf (archived: https://web.archive.org/web/20261025160037/https://epa.illinois.gov/content/dam/soi/en/web/epa/topics/environmental-justice/documents/ira/ira-analyses/23110003.pdf). Prime Data Centers, 1600 East Higgins Road, Elk Grove Village: construction permit, Application No. 24090003, issued July 15, 2025; “Thirty-nine (39) 3,250 kW (4,656 BHP) Diesel-Powered Emergency Generators with 20 Generators equipped with Diesel Particulate Filters”; Tier 2; “The runtime of each Diesel-Powered Emergency Generator shall not exceed 35 hours/year (1,365 hr/yr combined).” https://epa.illinois.gov/content/dam/soi/en/web/epa/topics/environmental-justice/documents/ira/24090003.pdf (archived: https://web.archive.org/web/20261025160113/https://epa.illinois.gov/content/dam/soi/en/web/epa/topics/environmental-justice/documents/ira/24090003.pdf). Illinois EPA Modeling Unit (Mohammad Sweid), modeling memorandum for Prime Data Centers, permit 24090003, June 4, 2025: the applicant’s consultant (Atmospheric) “developed a cumulative modeling analysis that incorporated background concentrations based on nearby monitoring data as well as nearby emission inventory sources”; modeled exceedances of the 1-hour NO2 NAAQS (total 363.90 µg/m³ against 188.68 µg/m³); Prime’s maximum impact at an exceedance 0.16 µg/m³ against a 7.52 µg/m³ significant impact level; “Prime would not cause or contribute to an exceedance the 1-hour NO2 NAAQS.” https://epa.illinois.gov/content/dam/soi/en/web/epa/topics/environmental-justice/documents/ira/prime-data-centers-modeling-memo.pdf (archived: https://web.archive.org/web/20261025160028/https://epa.illinois.gov/content/dam/soi/en/web/epa/topics/environmental-justice/documents/ira/prime-data-centers-modeling-memo.pdf). Illinois EPA environmental justice notification letter, January 22, 2026, Stream ORD, 2000 Landmeier Road, Elk Grove Village, Construction Permit Application 25120023: “construct a new data center which will consist of 126 2.5 MW diesel emergency generators.” https://epa.illinois.gov/content/dam/soi/en/web/epa/topics/environmental-justice/documents/notification-letters/2026/Stream%20ORD%20031440AWO%20Construction%2025120023.pdf (archived: https://web.archive.org/web/20261025155002/https://epa.illinois.gov/content/dam/soi/en/web/epa/topics/environmental-justice/documents/notification-letters/2026/Stream%20ORD%20031440AWO%20Construction%2025120023.pdf). Illinois EPA, Informal Resolution Agreement Analyses page (agreement “voluntarily entered into by Illinois EPA with USEPA on February 14, 2024”; permit, EJ/Title VI review, and modeling memorandum posted for “construction projects that meet the applicability requirements of the Informal Resolution Agreement”): https://epa.illinois.gov/topics/environmental-justice/informal-resolution-agreement-analyses.html (archived: https://web.archive.org/web/20261025132324/https://epa.illinois.gov/topics/environmental-justice/informal-resolution-agreement-analyses.html)
[6a] Southern Environmental Law Center, “Groups appeal permit for xAI’s South Memphis data center, decisions around unpermitted methane gas turbines,” July 16, 2025: permit issued July 2 for 15 turbines; SCHD “claimed that the federal Clean Air Act didn’t apply to xAI’s unpermitted gas turbines, citing an exemption for ‘nonroad engines’”; SELC: xAI was “unlawfully installing 35 polluting methane gas turbines at the site before getting a permit.” Timeline in SELC, “Inside Memphis’ fight against xAI”: 60-day notice of intent on behalf of the NAACP, after which “xAI removes all unpermitted turbines from the site,” then permit approval for 15. https://www.selc.org/news/inside-memphis-fight-against-xai/ (archived: https://web.archive.org/web/20261011221131/https://www.selc.org/news/inside-memphis-fight-against-xai/) and https://www.selc.org/press-release/groups-appeal-permit-for-xais-south-memphis-data-center-decisions-around-unpermitted-methane-gas-turbines/ (archived: https://web.archive.org/web/20260921144853/https://www.selc.org/press-release/groups-appeal-permit-for-xais-south-memphis-data-center-decisions-around-unpermitted-methane-gas-turbines/) [Advocacy source; SELC represents plaintiffs.]
[6b] Earthjustice, “NAACP Sues xAI for Illegal Pollution from Data Center Power Plant,” April 14, 2026. “xAI is illegally operating 27 gas turbines without an air permit in Southaven, Mississippi”; 60-day notice of intent “sent to xAI in February”; potential to emit “more than 1,700 tons of smog-forming nitrogen oxides (NOx) each year.” https://earthjustice.org/press/2026/xai-sued-for-illegal-power-plant (archived: https://web.archive.org/web/20260824150018/https://earthjustice.org/press/2026/xai-sued-for-illegal-power-plant) [Advocacy source; Earthjustice and SELC represent plaintiffs.]
[6c] Neil Strebig, Memphis Commercial Appeal, “NAACP alleges 57 turbines active at xAI Southaven site in lawsuit,” June 11, 2026 (republished by AOL as “57 turbines at xAI Southaven site, lawsuit cites emissions concerns”). MDEQ exemption of 18 temporary turbines, August 2025; count of 27 by December 2025; MDEQ PSD permit for 41 turbines approved March 10, 2026; MDEQ confirmation on May 13, 2026 that 46 turbines were operating without a permit; 57 on site per discovery emails of May 15, 2026; motion to amend filed June 10, 2026. https://www.aol.com/articles/57-turbines-xai-southaven-lawsuit-213632000.html (archived: https://web.archive.org/web/20261025155313/https://www.aol.com/articles/57-turbines-xai-southaven-lawsuit-213632000.html)
[6d] U.S. EPA, “Air Plan Approval and Air Quality Designation; TN; Redesignation of the Shelby County 2008 8-Hour Ozone Nonattainment Area to Attainment,” 81 Fed. Reg. 40816 (June 23, 2016), FR Doc. 2016-14807, effective July 25, 2016; maintenance plan for the Tennessee portion of the Memphis, TN-MS-AR area “through 2027.” https://govinfo.gov/link/fr/81/40816 (archived: https://web.archive.org/web/20261025162258/https://govinfo.gov/link/fr/81/40816)
[11v] Pioneer Development, LLC, “Project Cardinal, Air Quality Profile,” presentation at the United City of Yorkville City Council meeting of March 10, 2026, posted on the city’s Project Cardinal project page. “Over 89% of backup generators for data centers in Virginia … have Tier II controls,” sourced on the slide to “Virginia JLARC, Data Centers in Virginia (2024); Piedmont Environmental Council (2025); Virginia DEQ permit data”; commitments: “Tier IV controls,” “DPF,” “SCR,” “DOC,” “HVO renewable fuel,” “Testing and maintenance only,” “No other backup generator dispatch permitted per executed PUD Agreement with the City of Yorkville,” testing window of weekdays, 11 AM to 5 PM, non-holidays, “per Yorkville Ordinance 2025-53 and PUD Agreement”; “In 2024, the average ComEd customer experienced approximately 32 minutes of total outage for the entire year,” sourced to PA Consulting ReliabilityOne (2025), EEI Benchmark Study (2025), and the Illinois Commerce Commission Performance Metrics Report (2024); solid oxide fuel cell “Energy Server” option, “Up to 85% fewer backup generators if deployed,” “subject to procurement availability.” https://www.yorkville.il.us/DocumentCenter/View/12721/Project-Cardinal—Air-Quality-Deck_Presentation-3-10-26?bidId= (archived: https://web.archive.org/web/20261025151321/https://www.yorkville.il.us/DocumentCenter/View/12721/Project-Cardinal—Air-Quality-Deck_Presentation-3-10-26?bidId=) [Developer presentation; figures are the petitioner’s.]
[11w] United City of Yorkville, City Council Packet, June 10, 2025 (ArchiveCenter Item 6268). Written public comment correspondence, packet pp. 234 to 236: resident email of March 25, 2025 (“could cause significant noise pollution in this area to residents, causing neurological and mental health stressors in addition to medical issues and complications”) with links to Washington Department of Ecology, EPA DERA, American Cancer Society, and California Air Resources Board diesel pages, and City Administrator Bart Olson’s replies of March 27 and 31, 2025: that none of the data centers nearer the resident’s home will use well water, “neither their own or the City wells,” and “They are not anticipated to begin operation until well after we have converted to the Lake Michigan source”; “We have spoken with our government counterparts in Loudoun County Virginia, which is the data center capital of the world. They have spoken a bit about noise complaints being the most frequent issue cited by neighbors, but they tended to downplay the severity of it compared to your assertion of medical issues and complications.” Staff memorandum, Sara Mendez, Planner I, to the Planning and Zoning Commission, May 7, 2025, “PZC 2025-05 Data Center Development Standards, Text Amendment,” packet pp. 394 to 410, comparing Loudoun County, Prince William County, and Chandler standards (“While Yorkville is not looking to adopt Loudoun County’s standards exactly, it aims to implement similar best practices tailored to the City’s specific needs”); Loudoun generator testing hours as tabulated in the memo: May 1 to September 30, 5 to 7 p.m.; October 1 to April 30, 11 a.m. to 5 p.m.; table of twelve data center projects with nearest distance to a residential property line: Cyrus One ~2,230 feet; Prologis (Project Steel) ~3,500 feet; Daniels (South) ~130 feet; Daniels (North) ~98 feet; Green Door 50 acres ~4,300 feet; Green Door-Hagemann ~7,300 feet; Green Door-Kelaka ~1,500 feet; Green Door-Meyer ~0 feet; Hamman-Kelaka ~0 feet; Magnolia Hill Partners ~2,600 feet; Pioneer (Project Cardinal) ~460 feet; PGP Development ~650 feet. Draft ordinance, packet pp. 389 to 393, adopted as Ordinance 2025-53 on June 24, 2025 by a 7-0 roll call (draft minutes of the June 24, 2025 City Council meeting, in the July 22, 2025 City Council Packet, ArchiveCenter Item 6360, p. 20). https://www.yorkville.il.us/ArchiveCenter/ViewFile/Item/6268 (archived: https://web.archive.org/web/20251030032646/https://www.yorkville.il.us/ArchiveCenter/ViewFile/Item/6268) and https://www.yorkville.il.us/ArchiveCenter/ViewFile/Item/6360 (archived: https://web.archive.org/web/20261025162554/https://www.yorkville.il.us/ArchiveCenter/ViewFile/Item/6360)
[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)
[11y] United City of Yorkville, Planning and Zoning Commission, transcript of the public hearing on PZC 2025-08 (Pioneer Development, LLC, Project Cardinal), July 9, 2025, Vitosh Reporting Service (ArchiveCenter Item 6395, “PZC 7-9-25 Minutes & Transcript”). Sworn testimony of Matt McCarron for Pioneer Development: Ashburn homes “within 500 feet of data center campuses in Ashburn have been appreciated by approximately 70 percent over the last decade” (transcript p. 26); “legacy Ashburn data center campuses are built as close as a hundred, 130 feet from residential property lines. We’re committing to a minimum 500-foot setback” (pp. 26 to 27); generator testing “is only going to occur once or twice a year” and generators “are really never used outside of testing” (p. 25); “all backup generators meet Tier 4 final EPA standards” (p. 29); “if it’s curtailed in an emergency, we would be curtailed first and we would have backup generators. We are not going to cause a brownout” (p. 84). https://www.yorkville.il.us/ArchiveCenter/ViewFile/Item/6395 (archived: https://web.archive.org/web/20261025162533/https://www.yorkville.il.us/ArchiveCenter/ViewFile/Item/6395)
[19] LoudounNow (Hanna Pampaloni), “DEQ Launches Air Quality Monitoring in Ashburn’s Data Center Alley,” April 30, 2026. First phase began February 2026 with five sensors in eastern Loudoun; data collection began March 3; two more sensors added in April; PM2.5, carbon monoxide, and nitrogen dioxide; EPA grant funded. https://www.loudounnow.com/news/deq-launches-air-quality-monitoring-in-ashburn-s-data-center-alley/article_3e4aea6b-24bc-45fb-9f5e-4b5a1578fb23.html (archived: https://web.archive.org/web/20261025155322/https://www.loudounnow.com/news/deq-launches-air-quality-monitoring-in-ashburn-s-data-center-alley/article_3e4aea6b-24bc-45fb-9f5e-4b5a1578fb23.html)