PITTSBURG (CBS SF) — There will be no physical testing of the soils at Keller Canyon Landfill near Pittsburg for traces of radioactive waste, with a consultant’s report determining a “95 percent confidence level” that no such waste was dumped there between 2011 and 2017.

On Tuesday, the Contra Costa Board of Supervisors accepted a report from TRC Solutions Inc. that, based on a study of documents including special waste authorization agreements, investigation reports and bills of lading and manifests of loads in and out of the landfill, among other data from a construction project at the former Hunters Point Naval Shipyard in San Francisco during those years, it’s unlikely any radioactive soils ended up at the landfill outside Pittsburg.

County staff recommended against pursuing environmental field sampling at Keller Canyon, and the supervisors on Tuesday voted unanimously to accept that recommendation.

Jonathan Scheiner of TRC Solutions told the supervisors that to achieve absolute certainty about the radioactive waste, field testing of the leachate liquid that has percolated through the landfill would be necessary. Contra Costa County staff recommended against pursuing that testing, and the supervisors voted 5-0 Tuesday to accept the TRC Solutions forensic audit report.

News reports in April 2018 said that the U.S. Environmental Protection Agency learned soil testing results from Hunters Point were fabricated before waste soils were taken from there to several regional landfills, including Keller Canyon. The EPA said Keller Canyon may have received soils tainted by radioactivity.

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Two onetime supervisors with Tetra Tech, the firm testing the soils at Hunters Point, in May 2018 pleaded guilty in federal court to falsifying soil sample results.

The issue generated enough concern for Supervisor Federal Glover’s office to convene a public meeting in June 2018 in Bay Point, where representatives from federal, state and local regulatory agencies — including the Radiologic Health Branch of the California Department of Public Health — discussed the investigation and answered questions about the potential impact of radiological waste to local communities.

TRC’s forensic audit was finished in May 2019, and concluded it was “very unlikely” that radioactive materials from Hunters Point ended up at Keller Canyon. Follow-up county work was postponed as the COVID-19 crisis diverted resources, but virtual public meetings on the Keller Canyon soils were held on June 21 and Nov. 9 of this year.