PIKETON, Ohio — The U.S. Department of Energy submitted its 2025 groundwater monitoring report for the Portsmouth Gaseous Diffusion Plant to the Ohio EPA on Tuesday, confirming that significant chemical and radiological contamination persists across the 3,700-acre site — just two days before SoftBank Group and three cabinet secretaries are scheduled to arrive in Piketon to announce a long-term redevelopment plan for the property.
The report, prepared by Southern Ohio Cleanup Company LLC and dated February 2026, details monitoring data collected throughout calendar year 2025 from more than 100 wells across 18 contaminated areas at the former uranium enrichment complex.
The findings paint a picture of a site still grappling with a toxic legacy decades in the making — even as it is being positioned as the centerpiece of a billion-dollar energy infrastructure deal between the United States and Japan.
TCE concentrations climbing at worst locations
The most alarming finding in the report is at the X-701B Former Holding Pond, where monitoring well X701-130G recorded trichloroethene — a known carcinogen commonly referred to as TCE — at 120,000 micrograms per liter. The site’s cleanup goal for TCE is five micrograms per liter, meaning the concentration at this single well is 24,000 times higher than the remediation target.
The reading is also higher than the detections recorded at the same well between 2019 and 2022, when TCE ranged from 46,100 to 73,000 micrograms per liter. Rather than declining, TCE at one of the site’s worst contamination points is trending upward.
Other wells in the X-701B area also showed elevated or increasing levels. Well X701-79G recorded TCE at 507 micrograms per liter, up from 319 in 2024. Two wells in the Quadrant II plume — X705-03G and X701-45G — are also trending upward at 34.9 and 39.4 micrograms per liter, respectively. Both readings are roughly seven to eight times the cleanup standard.
The report confirms that four active groundwater plumes consisting primarily of TCE remain at the site.
Contamination reaching surface water
The contamination is not confined to groundwater. TCE was detected at 62.7 micrograms per liter in surface water collected from the East Drainage Ditch — more than 12 times the cleanup goal. TCE is also routinely detected in Little Beaver Creek, which receives groundwater discharge from the site.
Technetium-99, a radioactive byproduct of uranium enrichment with a half-life of approximately 211,000 years, was detected at levels up to 26.9 picocuries per liter in the East Drainage Ditch and Little Beaver Creek. The DOE characterized the finding as less than 0.007% of its internal derived concentration standard but acknowledged that the radioactive isotope continues to appear in the waterways surrounding the plant.
Uranium above drinking water standards
Uranium was detected above the Ohio EPA drinking water standard of 30 micrograms per liter in groundwater samples collected from X-701B monitoring wells within the interim remedial measure treatment area. The report does not specify exact concentrations in the body of the document.
Uranium was also detected in the site’s drinking water supply at up to 1.66 micrograms per liter — below the regulatory limit. No transuranics or technetium-99 were found in the drinking water supply.
The DOE emphasized that groundwater beneath the site is prohibited from use as drinking water and is not hydraulically connected to the Scioto River Valley buried aquifer that serves the surrounding community. However, the detection of both TCE and technetium-99 in surface water raises questions about the extent to which contaminants are migrating beyond the boundaries of the groundwater system.
Chromium, TCE expanding at other locations
At the X-616 Former Chromium Sludge Surface Impoundments, chromium was detected at 917 micrograms per liter in well X616-05G — more than nine times the preliminary remediation goal of 100 micrograms per liter. The report notes that chromium is “routinely detected” above the cleanup goal at this well.
The report also acknowledges that TCE has been “slowly increasing” in several X-616 monitoring wells over the past 25 years. In 2024, the DOE identified what it called a potential new TCE plume on the west side of the former surface impoundments. Additional sampling in 2025 led the agency to conclude that a defined plume is not present, though TCE continues to be detected in the wells, and quarterly monitoring will continue into 2026.
At the X-740 Former Waste Oil Handling Facility, TCE was detected above the cleanup goal in two monitoring wells within the restored excavation area. At one of those wells, X740-26B, TCE was found in the area where concentrations were highest before soil was excavated from the site.
Radiological data carries no enforcement weight
The report includes an unusual caveat regarding its radiological findings. The DOE states that radiological data are collected in accordance with DOE Order 458.1 and are included in the report “as information only.” The 1999 Director’s Final Findings and Orders — the legal framework governing cleanup at the site — states that tasks specific to radiological contamination “are not specifically enforceable under that Order.”
Timing raises questions
The report was submitted to Ohio EPA on Tuesday — the same day the RSVP deadline closed for a Friday announcement at the Piketon site involving SoftBank Group, SB Energy, and three senior members of the Trump cabinet.
The media advisory for Friday’s event states that the announcement involves a “long-term plan” for the redevelopment of the DOE Portsmouth site. On the same ground, the DOE is reporting TCE at 24,000 times the cleanup goal, uranium above drinking water standards, and technetium-99 in the waterways.
Pike County carries some of the highest cancer and premature death rates in Ohio. A study by epidemiologist Joseph Mangano found that the county’s premature death rate for residents under 74 was 107% higher than the national average between 2021 and 2023.
The Guardian has previously reported on the contamination crisis at the site, including the 2019 closure of Zahn’s Corner Middle School after enriched uranium and neptunium-237 were detected inside the building, deliberate releases of radioactive gas known as “Midnight Rockets” confirmed by declassified documents and an incident in December in which nearly 14 Notices of Violation tied to hazardous waste at the site briefly appeared on the Ohio EPA’s public portal before being removed within hours.
What’s next
The DOE plans to continue quarterly monitoring at several locations in 2026, including five wells at the X-616 area where TCE has been increasing. The Southern Ohio Cleanup Company LLC, which assumed responsibility for cleanup activities on October 1, 2025, will continue environmental restoration and monitoring at the site.
Friday’s announcement is scheduled for 12:45 p.m. at Piketon. Speakers include Energy Secretary Chris Wright, Commerce Secretary Howard Lutnick, Interior Secretary Doug Burgum, and SoftBank Chairman and CEO Masayoshi Son. The event is part of the U.S.-Japan Strategic Trade and Investment Agreement.
The full 2025 Groundwater Monitoring Report is available here.
Source: DOE/PPPO/03-1370&D1, 2025 Groundwater Monitoring Report for the Portsmouth Gaseous Diffusion Plant, Piketon, Ohio. Submitted to Ohio EPA on March 18, 2026.