TC Energy will soon perform routine maintenance on our natural
gas pipeline in your area. As part of this work, you may hear a
particularly loud noise known as a “blowdown.”
A blowdown is the act of releasing natural gas from a section
of pipeline so work can be done safely. TC Energy employees
will close several valves to isolate that section of the pipeline
and then open a blowdown valve to release any natural gas.
A loud roaring sound occurs when the natural gas, which is
compressed into the pipe at very high pressure, escapes through
the opening. The gas extends upward in a plume to between 30
and 60 metres (100 and 200 feet) high.
For more details, login as a member and view the document from TC Energy.