The only signs investigators found of the chemical-laden railroad hopper car that exploded after it derailed last year in Rosedale were twisted and deformed pieces of its aluminum shell that shot out like shrapnel, landing as far as 370 feet away.
"Of the larger wreckage pieces recovered along [adjacent] Lake Drive, was a brake valve weighing about 70 pounds, a piece of aluminum rail car frame, and a fractured piece of burnt rail tie," wrote Paul L. Stancil, the National Transportation Safety Board's senior hazardous materials investigator, in a factual report on the explosion released Monday.
The document, one of 179 made public with the opening of the NTSB's investigative docket in the case Monday, stands out because it details the strength of the explosion and the scope of the chemical fire and spills caused by the derailment. While the cause of the accident is known already — the CSX train jumped the tracks after a dump truck pulled out in front of it, the nature of the chemical release has only been vaguely described until now.
A final NTSB report on the accident is still pending but can be expected soon.
Not long after the explosion occurred, officials announced that the chemical spill posed no danger to local residents, but details were limited.
Stancil's report also notes that the May 28, 2013, explosion — which seriously injured the truck driver and a worker at an adjacent building — has compounded existing concerns about contamination in the area.
The accident scene overlaps with an 18-acre site known as the "68th Street Dump," a collection of landfills used from the 1950s through the 1970s that since 1984 has been listed as a priority for intense environmental remediation by the Environmental Protection Agency.
"Historical investigation reports and EPA investigations have identified several sources of industrial wastes that were disposed on the site, involving the disposal of volatile organic compounds, polynuclear aromatic hydrocarbons, polychlorinated biphenyls, pesticides, and metals," Stancil's report said.
The site, which straddles the line between Baltimore and Baltimore County, has been subject to three efforts to remove hazardous waste and other chemicals in the past. Water runoff from the site feeds into Herring Run and tributaries to it, and ultimately Back River and the Chesapeake Bay.
The explosion released 218,279 pounds of sodium chlorate from the destroyed hopper car, according to Stancil's report. It also tore open two of four cars that were collectively carrying 795,496 pounds of powdered terephthalic acid.
The strong chemical fire sparked in the two acid-laden cars burned until early the next day. Firefighters pumped 750,000 to 1 million gallons of water onto the scene to suppress the fire, which spread the chemicals further.
In the incident's wake, CSX hired two firms to conduct air, water and soil monitoring within a two-mile radius of the explosion, the report said.
The tests found that "no combustion gases or volatile organic compounds were detected in the community surrounding the derailment site, and particulate matter was within normal limits for an urban area," the report said.
However, surface water and sediment samples "yielded evidence that measurable levels of terephthalic acid and other contaminants entered a tributary of Back River" downstream from the site, the report said.
Between May 29 and June 2, remediation crews hauled 580 cubic yards of terephthalic acid and "associated debris" from the scene and transported it to CSX's Bayview Yard off U.S. 40 for temporary storage before disposal, the report said.
The Maryland Department of the Environment, which helped coordinate the cleanup, could not be reached for comment.
In a statement, CSX spokesman Rob Doolittle said the railroad follows all federal safety standards for transporting chemicals, including those that apply to the construction of tank cars. It also conducts "extensive training activities" with first responders in communities where it operates, Doolittle said, including on hazardous materials responses.
In addition to its remediation efforts and testing following the Rosedale explosion, Doolittle said CSX met with area residents "to answer their questions about any concerns they might have had regarding their safety and the environmental impact of the incident."