EAST PALESTINE (WKBN) — The Environmental Protection Agency (EPA) sent notice to a company for what the EPA classified as a failure to maintain data quality standards in groundwater sampling conducted at the East Palestine train derailment site.

In a news release on its website, the EPA says that Tetra Tech Inc. used a subcontractor, ALS Houston, to test groundwater samples in the fall of 2025.

According to the EPA, during its quality control process in Sept. 2025, the EPA discovered potential discrepancies in groundwater sampling data for 2-butoxyethanol, a colorless solvent used in household cleaners, paints, varnishes and paint strippers.

At that time, the agency held all data from ALS Houston and ordered the prime contractor, Tetra Tech, to perform additional data validation on data from August, September and October.

In December 2025, after finding more discrepancies, the EPA sent additional samples to its laboratory, which confirmed there was no 2-butoxyethanol detected, according to the release from the EPA.

In January 2026, the EPA sent additional August-October samples to the lab for re-analysis, and those tests confirmed there was no 2-butoxyethanol in the samples, according to the EPA.

As the agency’s investigation continued, in February 2026, Tetra Tech notified EPA that ALS Houston had altered measurements and terminated two data analysts for failing to follow the laboratory’s standard operating procedures. This failure to follow procedures resulted in false levels of detection, according to the news release from the EPA.

“Thanks to the agency’s quick action, none of the falsified data was used to make any health, safety, cleanup, or enforcement decisions at the site. Rigorous and ongoing validating analysis continues to confirm there is no ongoing exposure to toxic chemicals from the derailment endangering public health or the environment in East Palestine,” read the release.

The EPA has since rejected data submitted by ALS Houston and referred the data quality issues to the EPA’s Office of Inspector General. The EPA is now reviewing all active contracts with the subcontractor, as well as reviewing the EPA’s own quality assurance and control process.

The Village of East Palestine, on its Facebook page, released a statement regarding the issue:

“While reports indicate that the error is limited in time and scope, and relates only to one tested chemical, we are closely coordinating with the US EPA to ensure follow through on the investigation and reporting. News of this issue is disheartening however we are pleased to learn that the issue was identified during oversight, addressed, and according to US EPA presents no known threat to groundwater quality or safety,” read the statement.

WKBN tried reaching out to Tetra Tech and ALS via phone and email, but has not yet heard back from either company.

WKBN also reached out to the EPA for more information on the notice that was issued.

The EPA’s news release states that the agency will continue to update its website with the most up-to-date information.