On March 20, 2024, at noon, an employee, 34, was pneumatically leak-testing a newly installed 56-inch drainpipe. The pipe extended from one side of the street to the other, roughly 150 feet. They placed a rubber pressure plug on one side and another on the testing site across the street. At about 30 minutes into the air leak testing, they noticed the pressure on the pipe had decreased, so the employee descended to the bottom of the trench and began to apply soapy water around the edges of the plug.