A company testing for emissions said its interim report greatly exaggerated the levels of benzene above a Fort Worth gas drilling site.
Eastern Research Group, which is conducting the study for the city, discovered what it called a small error. But that error caused major problems with preliminary results.
The preliminary report said that a site at Mercado Drive, just north of downtown, was producing 103.78 tons per year of emissions. But after fixing the miscalculation, it turns out the site only produces 0.353 tons per year.
"It was very unfortunate that there was a mistake in that data," city spokesman Jason Lamers said. "We've made that correction with ERG, and we've assured that ERG won't make that mistake again."
Eastern Research Group had not fully completed the second phase of the seven-part study when the City Council was briefed in February after it asked for an update. The briefing on the preliminary data showed that the Mercado Drive site and another well site were producing more emissions then they are supposed to.
The Mercado Drive site is operated by Chesapeake Energy, which is cooperating with the study.
"Chesapeake is pleased that Eastern Research Group's calculation error -- which overstated the emissions at our Mercado site by more than 300 times -- has been identified and corrected," spokesman Brian Murnahan said in a statement. "We appreciate the additional quality assurance precautions ERG has put into place and look forward to the release of the final report. "
The complete data collection and analysis are still months away from completion, which means all numbers are subject to change.
But if there's a silver lining to the mistake, it's that emissions are better than first thought.
"Only one well now has an elevated level we need to take a look at with the state, so overall things are going pretty well, so that's good news," Lamers said.
The completed report is due June 30.