PITTSBURGH (AP) - EQT Corp. told the Pennsylvania Department of Environmental Protection that it sent 21 tons of drill cuttings from Marcellus Shale wells to area landfills in 2013.

But landfills in southwestern Pennsylvania told a different story.

Six facilities in this part of the state reported receiving nearly 95,000 tons of drill cuttings and fracking fluid from the Pittsburgh-based oil and gas operator in 2013.

The landfills’ records are the correct ones, said Mike Forbeck, waste management director with the DEP. He said the agency has opened an investigation into drillers’ underreporting of landfill waste.

The EQT case -- 21 tons vs. 95,000 tons -- may be the most dramatic example of how data submitted by oil and gas operators don’t match reporting required of landfills. The DEP said it has been aware of the problem for "a number of months" and is looking into why the different reporting channels aren’t yielding the same results.

When the EQT figures were brought to its attention, the DEP launched an investigation into the company’s reporting practices, said John Poister, a spokesman for the agency.

Asked for comment on inconsistencies in waste sent to landfills by Range Resources in 2013, the DEP started another investigation and found that Range’s numbers were off by 22,000 tons compared with what landfills reported receiving from the Texas-based driller in 2013.

Range’s spokesman Matt Pitzarella said the company did its own review and "noted document discrepancies that we are currently working with our vendors and the DEP to correct."

The DEP would not say if other companies are being investigated as part of the agency’s probe.

Across the board, nine southwestern Pennsylvania landfills analyzed reported accepting three to four times the amount of waste that operators said they sent there.

Some landfills, such as Imperial, in Allegheny County, reported accepting waste from a handful of operators that never indicated the facility as a destination in 2013. Drill cuttings and fracking fluid waste from Range Resources, Royal Dutch Shell, Consol Energy, Rex Energy and Energy Corp. of America ended up at the landfill in 2013, but only Denver-based Energy Corp. of America listed Imperial as a disposal target.

Spotting inconsistencies in the amount of waste at landfills is difficult for several reasons, the main one being that drilling operators report their waste electronically with data stored in a database on the DEP’s website. Landfills send paper copies of spreadsheets that are stored in binders at regional DEP offices.

"We also believe that, in many cases, what is filed electronically are estimates and not necessarily based on real numbers which would be available from the landfills," Poister said.

To that end, the DEP’s investigation might result in standards for estimating and reporting, he said.

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