More than 33,500 gallons of gasoline spilled from a Sunoco pipeline along Darby Creek in Tinicum Township near Philadelphia International Airport in June, according to recently released federal data.

The release created a sheen on the creek and crews were sent to contain the spill from a 12-inch pipeline that Sunoco plans to use as it constructs the Mariner East 2 pipeline for natural gas tapped from the Marcellus Shale.  The pipeline was manufactured in 1937.

The Pipeline and Hazardous Materials Safety Administration released a spreadsheet last week containing data on the accident, classifying it as a significant — but not serious — spill.  The data were supplied by Sunoco.  Until then, there were few publicly available details of the incident. The release of the new data was first reported by State Impact Pennsylvania.

Sunoco Pipeline LP is owned by Energy Transfer of Houston. Representatives from Energy Transfer could not immediately be reached for comment.

"This happened on a pipeline that Sunoco now proposes to repurpose to carry more dangerous hazardous highly volatile liquids," said Eric Friedman of Del-Chesco United for Pipeline Safety, a coalition of grassroots groups opposing the Mariner East 2.  "It strikes me as the height of recklessness."

The spill, according to Friedman, was initially reported by operators on a passing Conrail train.  He said the spill is "one of four known accidents on this same 1930s-era pipeline."

The report says that Sunoco was notified at 6:05 p.m. on June 19 of a petroleum odor near Darby Creek.  Crews sent by Sunoco to investigate confirmed the odor and sheen along the creek.  More workers were sent to rig a boom to contain the spill by 9:45 p.m. and set up a command team.  Despite pressure testing two pipelines, crews could not initially locate the source.

The company filed a report June 21 saying the source was still unknown.  It wasn't until June 26 that crews identified the source as the 12-inch line that runs from Point Breeze in Philadelphia to Montello in Berks County.  The steel pipeline was buried four feet below pavement and just offshore.  The failed portion of the pipe was dug up and replaced.

In all, 798 barrels of gasoline were spilled — or 33,516 gallons.  Of that, about 7,220 gallons were released into the creek.

The spill contaminated soil, as well as groundwater and surface water.  But Sunoco reported that it began remediating the spill and no wildlife was affected.  In the cleanup, which cost $3.6 million, 21,378 gallons were recovered. Remediation continues.

The spill is still under investigation.  Sunoco said it will file a report on the cause once metallurgical testing of the pipe is complete.