US STEEL MON VALLEY WORKS - CLAIRTON PLANT

U.S. Steel Mon Valley Works — Clairton Plant (EPA Registry ID 110042043384), the largest coke-making facility in North America, recorded eight quarters with non-compliance and approximately $4.27 million in attributable penalties over the trailing 24 months, derived from a five-year penalty total of $10,676,815 [source: https://pollutionscan.com/facility/110042043384/us-steel-mon-valley-works-clairton-plant-clairton-pa] [source: https://echo.epa.gov/files/echodownloads/echo_exporter.zip]. PollutionScan's EPA-data-derived scoring places the facility at Grade F (13/100). Across the five-year baseline, ECHO records show 15 inspections, 20 violation quarters, and 11 formal enforcement actions [source: https://pollutionscan.com/facility/110042043384/us-steel-mon-valley-works-clairton-plant-clairton-pa]. Clean Air Act status has dominated the compliance record throughout that period, while RCRA hazardous-waste status remains largely unknown across recent quarters [source: https://pollutionscan.com/facility/110042043384/us-steel-mon-valley-works-clairton-plant-clairton-pa].

Two events define the current briefing window. On August 11, 2025, an explosion inside the reversing room killed two workers and injured ten others; federal investigators subsequently cited two Pennsylvania employers in connection with the incident [source: https://www.post-gazette.com/business/career-workplace/2025/08/17/clairton-coke-works-us-steel-nippon-explosion/stories/202508240012] [source: https://www.abc27.com/pennsylvania/two-pennsylvania-employers-cited-following-2025-us-steel-plant-explosion/]. Then, on September 16, 2025, EPA issued an Order granting in part a Title V petition that challenged the Allegheny County Health Department operating permit (Permit No. 0050-OP22a), reopening portions of the air permit for revision [source: https://www.epa.gov/system/files/documents/2025-09/us-steel-clairton-ii-order_9-16-25.pdf]. Ownership of the facility transferred to Nippon Steel following its $11 billion U.S. investment program. That transfer means the full weight of Clairton's open environmental and safety matters now sits with the new parent [source: https://www.alleghenyfront.org/deadly-explosion-safety-environmental-lapses-u-s-steel-clairton-coke-works-nippon/] [source: https://canarymedia.com/articles/green-steel/us-steel-build-2b-plant-arkansas].

EPA ECHO data as of May 4, 2026 attributes eight quarters with non-compliance and roughly $4.27 million in 24-month penalty exposure to the Clairton Plant (Facility ID 110042043384), derived from a five-year total of $10,676,815 prorated across the 24-month window [source: https://echo.epa.gov/files/echodownloads/echo_exporter.zip] [source: https://pollutionscan.com/facility/110042043384/us-steel-mon-valley-works-clairton-plant-clairton-pa]. The facility carries Major status under both the Clean Air Act and the Clean Water Act, and is a Large Quantity Generator under RCRA [source: https://pollutionscan.com/facility/110042043384/us-steel-mon-valley-works-clairton-plant-clairton-pa]. ECHO records show 15 inspections and 11 formal actions over the five-year baseline [source: https://pollutionscan.com/facility/110042043384/us-steel-mon-valley-works-clairton-plant-clairton-pa].

The chronology of key actions runs as follows. On March 26, 2024, U.S. Steel announced that EPA and the Department of Justice had authorized a consent decree covering Clairton Plant incidents, resolving a slate of legacy air issues tied to coke-oven battery operations [source: https://investors.ussteel.com/news-events/news-releases/detail/670/u-s-steel-consent-decree-for-clairton-plant-incidents]. Eight months later, on November 19, 2024, U.S. Steel filed Petition No. III-2024-29 with EPA, challenging the Allegheny County Health Department's operating permit (Permit No. 0050-OP22a) [source: https://www.epa.gov/system/files/documents/2025-09/us-steel-clairton-ii-order_9-16-25.pdf]. That petition arrived against a backdrop of prior regulatory scrutiny — environmental groups had already secured a split EPA decision in October 2023 finding inadequate emission testing and compliance schedules in the permit structure, as TribLive reported [source: https://naviga.triblive.com/local/regional/environmental-groups-claim-victory-in-epa-ruling-on-u-s-steel-plant-in-clairton/]. August 11, 2025 brought the most acute event in the window: an explosion at the Clairton Coke Works killed two employees and injured ten, with reporting indicating that workers had been manipulating valves in the reversing room before the blast [source: https://www.post-gazette.com/business/career-workplace/2025/08/17/clairton-coke-works-us-steel-nippon-explosion/stories/202508240012]. Five weeks later, on September 16, 2025, the EPA Administrator issued an Order granting in part and denying in part the Title V petition, directing the Allegheny County Health Department to revise portions of the operating permit [source: https://www.epa.gov/system/files/documents/2025-09/us-steel-clairton-ii-order_9-16-25.pdf]. In February 2026, the U.S. Department of Labor cited two Pennsylvania employers in connection with the August explosion [source: https://www.abc27.com/pennsylvania/two-pennsylvania-employers-cited-following-2025-us-steel-plant-explosion/].

The Allegheny Front reported in February 2026 that Nippon Steel, which closed its acquisition of U.S. Steel, now inherits the Clairton Works' pending safety and environmental matters, with detailed upgrade plans not yet public [source: https://www.alleghenyfront.org/deadly-explosion-safety-environmental-lapses-u-s-steel-clairton-coke-works-nippon/]. Nippon has pledged Mon Valley upgrades as part of an $11 billion U.S. investment package. The most visible capital commitment to date, however, is $1.9 billion directed to a direct-reduced iron facility at Big River Steel Works in Osceola, Arkansas — not at Clairton [source: https://www.post-gazette.com/business/powersource/2026/04/29/us-steel-arkansas-plant-nippon/stories/202604290070] [source: https://canarymedia.com/articles/green-steel/us-steel-build-2b-plant-arkansas]. KFF Health News reported in April 2026 that federal environmental-rule rollbacks are actively shaping Clairton's near-term compliance trajectory, adding another layer of uncertainty to the facility's forward outlook [source: https://kffhealthnews.org/news/article/clairton-pennsylvania-us-steel-make-america-healthy-again-maha-coal-coke/].

March 26, 2024 — Consent Decree (CAA). U.S. Steel disclosed through its investor-relations portal that EPA and the Department of Justice had authorized a consent decree covering incidents at the Clairton Plant. The release references coke-oven battery incidents governed by the Clean Air Act [source: https://investors.ussteel.com/news-events/news-releases/detail/670/u-s-steel-consent-decree-for-clairton-plant-incidents].

November 19, 2024 — Title V Petition Filed (CAA §505(b)(2)). U.S. Steel filed Petition No. III-2024-29 challenging operating permit 0050-OP22a issued by the Allegheny County Health Department [source: https://www.epa.gov/system/files/documents/2025-09/us-steel-clairton-ii-order_9-16-25.pdf]. That filing followed a parallel environmental-group petition which, per TribLive's October 2023 reporting, had already secured a split EPA decision finding inadequate emission testing and compliance schedules embedded in the permit structure [source: https://naviga.triblive.com/local/regional/environmental-groups-claim-victory-in-epa-ruling-on-u-s-steel-plant-in-clairton/].

August 11, 2025 — Fatal Explosion. Two workers died and ten were injured when a blast tore through the reversing room at the Clairton Coke Works. Reporting indicates workers had been manipulating valves immediately prior to the event [source: https://www.post-gazette.com/business/career-workplace/2025/08/17/clairton-coke-works-us-steel-nippon-explosion/stories/202508240012] [source: https://www.wtae.com/article/pennsylvania-clairton-us-steel/70313498].

September 16, 2025 — EPA Title V Order. The EPA Administrator issued an Order granting in part and denying in part Petition No. III-2024-29, directing permit revisions to Permit No. 0050-OP22a [source: https://www.epa.gov/system/files/documents/2025-09/us-steel-clairton-ii-order_9-16-25.pdf].

February 23, 2026 — Department of Labor Citations. The U.S. Department of Labor cited two Pennsylvania employers following its federal investigation into the August 11, 2025 explosion [source: https://www.abc27.com/pennsylvania/two-pennsylvania-employers-cited-following-2025-us-steel-plant-explosion/]. Penalty dollars tied to each specific enforcement action are not itemized in the available source set. Aggregate 24-month penalty exposure, derived from ECHO-sourced records, is approximately $4,270,726 [source: https://echo.epa.gov/files/echodownloads/echo_exporter.zip] [source: https://pollutionscan.com/facility/110042043384/us-steel-mon-valley-works-clairton-plant-clairton-pa].

Clairton Plant (Clairton, PA — 400 State Street, Allegheny County, Facility ID 110042043384) is the sole U.S. Steel site in the ECHO pull for this briefing. PollutionScan, drawing on EPA data, rates it Grade F (13/100), with 20 violation quarters and $10,676,815 in five-year penalties [source: https://pollutionscan.com/facility/110042043384/us-steel-mon-valley-works-clairton-plant-clairton-pa]. The site holds Major status under both the CAA and the CWA and is classified as a RCRA Large Quantity Generator [source: https://pollutionscan.com/facility/110042043384/us-steel-mon-valley-works-clairton-plant-clairton-pa]. Positioned on the Monongahela River approximately 10 miles south of Pittsburgh, it is the largest coke-producing plant in North America [source: https://en.wikipedia.org/wiki/Clairton_Coke_Works]. The surrounding Mon Valley airshed is governed by Title V operating permit (Permit No. 0050-OP22a), portions of which were reopened under the September 16, 2025 EPA Order [source: https://www.epa.gov/system/files/documents/2025-09/us-steel-clairton-ii-order_9-16-25.pdf].

Local employment reporting attributes 1,200 manufacturing jobs and approximately $3 billion in annual regional economic output to the plant, per Pennsylvania Manufacturers' Association estimates cited by Butler Eagle and KFF Health News [source: https://butlereagle.com/20260420/clairton-faces-fallout-from-environmental-rule-rollback] [source: https://kffhealthnews.org/news/article/clairton-pennsylvania-us-steel-make-america-healthy-again-maha-coal-coke/]. ECHO's EJ index average is reported as 0.0 in the data pull — a gap in the dataset rather than a measured zero — so community exposure is better indexed through the Title V record and the health reporting cited above. On-site contamination conditions surfaced in an unexpected form in May 2026, when four kittens recovered from the plant property were described as coated in toxic tar [source: https://wtae.com/article/pennsylvania-kittens-rescued-clairton/71168291].

ECHO's top_pollutants array returned empty in the facility pull, so the pollutant profile here is reconstructed from primary permit and sustainability documents rather than from TRI top-line figures [source: https://echo.epa.gov/files/echodownloads/echo_exporter.zip]. Coke-oven emissions form the core air-pollution profile. U.S. Steel's own Clairton Works Operations and Environmental Report identifies coke-battery emissions regulated under NESHAP/MACT as the primary concern, including benzene-soluble organics and coke-oven gas constituents [source: https://www.ussteel.com/documents/40705/71641/USS+Clairton+Works+Operations+Environmental+Report+2021.pdf/5734848a-2bbf-6448-9cab-7d008a23f160?t=1646082857897]. EPA's IRIS program classifies coke-oven emissions as human carcinogens. Exposure pathways are primarily inhalation downwind of the batteries and dermal contact with condensed tars.

Sulfur dioxide and hydrogen sulfide represent a second tier of concern. The September 16, 2025 Title V Order addresses emission testing and compliance schedules for combustion-source pollutants governed by NAAQS [source: https://www.epa.gov/system/files/documents/2025-09/us-steel-clairton-ii-order_9-16-25.pdf]. The Mon Valley airshed carries historical SO2 non-attainment exposure. Environmental petitioners — per TribLive's October 2023 reporting — won EPA concurrence that emission testing under the prior permit was inadequate [source: https://naviga.triblive.com/local/regional/environmental-groups-claim-victory-in-epa-ruling-on-u-s-steel-plant-in-clairton/].

Particulate matter (PM2.5) and polycyclic aromatic hydrocarbons (PAHs) round out the documented profile. U.S. Steel's 2022 Operations & Environmental Report describes PM control systems across by-products and quench-tower operations [source: https://www.ussteel.com/documents/40705/71641/USS+Clairton+Works+Operations+Environmental+Report+2022.pdf/670a411b-11a5-17ce-72c7-1c246125c561?t=1678740507328%2F5734848a-2bbf-6448-9cab-7d008a23f160%3Ft%3D1646082857897]. PM2.5 and PAHs are linked to cardiovascular and respiratory outcomes. KFF Health News' April 2026 reporting frames the EJ implications for Clairton residents under current federal rule settings, noting that rollbacks to those rules are already affecting the compliance calculus at the plant [source: https://kffhealthnews.org/news/article/clairton-pennsylvania-us-steel-make-america-healthy-again-maha-coal-coke/].

The NAICS 331111 peer benchmark returned no rows in this research bundle, so a quantitative peer ranking cannot be constructed from the provided sources [source: https://echo.epa.gov/files/echodownloads/echo_exporter.zip]. Clairton is widely described as the largest coke-making facility in North America, which limits direct comparability within the iron-and-steel mills NAICS code. The closest operational analogs are other integrated coke-and-steel sites. Gary Works is one such site: Chicago Tribune reporting identifies it as similarly positioned for green-steel investment decisions, with local advocates pressing for the same lower-carbon capital commitments that Nippon has directed to Arkansas [source: https://chicagotribune.com/2026/05/03/as-u-s-steel-announces-clean-steel-facility-in-arkansas-nwi-activists-want-the-same-in-gary] [source: https://en.wikipedia.org/wiki/Clairton_Coke_Works].

No SEC 10-K or 10-Q filings were returned in the research bundle for this entity — the parent's CIK is not included in the pull, and the facility itself is not a separate registrant [source: https://echo.epa.gov/files/echodownloads/echo_exporter.zip]. Forward-looking environmental risk must therefore be drawn from non-SEC primary sources. The September 16, 2025 EPA Title V Order signals that portions of the Clairton operating permit will be revised, with direct implications for monitoring requirements, emission testing protocols, and compliance schedules [source: https://www.epa.gov/system/files/documents/2025-09/us-steel-clairton-ii-order_9-16-25.pdf]. The Allegheny Front reports that Nippon Steel, post-closing, now carries the facility's open safety and environmental matters, and that detailed upgrade plans for the Mon Valley site have not been publicly released as of February 2026 [source: https://www.alleghenyfront.org/deadly-explosion-safety-environmental-lapses-u-s-steel-clairton-coke-works-nippon/].