That odor was natural gas, according to the National Transportation Safety Board's newly-released findings on the West Reading explosion.
As local authorities shifted their focus to cleanup management and community leadership, federal officials have continued to investigate the scene.
The blast site, securing evidence, and interviewing witnesses, were all part and parcel of the NTSB report, released Tuesday, May 2.
Around 35 office workers and 70 production employees were in the two RM Palmer buildings on South 2nd Avenue at the time of the explosion around 5 p.m. on March 24, investigators wrote. Workers in both buildings reported "an odor of natural gas" and "the smell of rotten eggs" in the moments leading up to the blast.
In RM Palmer building two, which was completely destroyed by the explosion, workers were sanitizing equipment in the final moments, NTSB found.
Federal regulators said that two UGI pipelines carried natural gas to the RM Palmer site — a 4-inch steel main along South 2nd Avenue in front of building two, and a 1.25-inch plastic main along Cherry Street between the RM Palmer buildings.
However, UGI told NTSB that they were not performing work in the area at the time, and reported "no pressure spike in gas usage before the explosion."
NTSB said they will continue to investigate the matter off-site by examining the evidence and data collected from the scene. According to West Reading officials, it could take up to two years for the full investigation to conclude.
Meanwhile, borough authorities said that the owners of affected properties are "working hand-in-hand" with officials on the remediation effort. Damaged sites including C&S Supply (200 Penn Ave.), 5 S. 2nd Avenue, and RM Palmer building one (77 S. 2nd Ave.) will "soon be returned to the owners," who will then complete the cleanup process, they said.
"We anticipate continued security on the affected block as these efforts continue," borough officials said in a statement.
"The affected block of S. 2nd Avenue will remain closed for the foreseeable future to ensure the safety of our residents and the workers at the site," they said, adding that there is no timeline for reopening.
In the meantime, area residents should brace for "loud noises, dust, and debris" as cleanup continues.
In addition to the seven RM Palmer workers who died in the March 24 blast, 11 people were injured, and three families were displaced, according to the NTSB.
Click here for the full NTSB preliminary findings, or here for the West Reading Borough statement.
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