The state Department of Environmental Protection has given Trinity Industries Inc. an extension on its investigation of the company’s former railcar sites in Greenville and Hempfield Township.

Trinity’s original deadline was July 23 to complete the investigation of hazardous waste on the properties and submit a report outlining cleanup plans, according to a DEP news release issued Thursday.

It now has until Dec. 3 to do so and requested the extension because of problems accessing the north plant in Greenville, which Trinity sold in 2004 to Commerce Park of Greenville Inc. and bought back in May.

“Trinity is committed to fulfilling its obligation in a timely manner,” said Trinity spokesman David Margulies of Margulies Communication Group, Dallas.

The extension was granted after DEP considered delays Trinity encountered beyond the company’s control, said Kelly Burch, DEP’s northwest regional director.

Trinity tried to access the site of the north plant but Commerce Park denied it entry to collect soil and groundwater samples, the news release said.

Work continued at the Trinity-owned south plant in Hempfield, where a consultant recently found traces of arsenic and lead. The ongoing investigation encompasses both plants, Margulies said.

Trinity has been inspecting the sites of the former railcar plants as part of a consent agreement with DEP and the state Attorney General’s office.

In early 2006, Trinity was charged by the Attorney General’s office with illegally dumping hazardous waste at both sites during railcar production. An agreement was reached in December 2006 ordering Trinity to clean up the sites and pay fines and costs.

In June 2007, Trinity sued Commerce Park seeking help with the cleanup, claiming Commerce Park contributed to dumping hazardous waste when crews demolished structures on the property to make way for future development.

Commerce Park officials denied Trinity’s allegations. The lawsuit was settled as part of Trinity’s purchase agreement with Commerce Park.

Greenville Mayor Richard H. Miller has been concerned with delays in the cleanup, but said Trinity’s need for an extension is reasonable.

“We’re going to be patient,” he said of borough officials and residents.