Yes a typical pipeline junction. Pig launchers and receivers. Junction tie in valve. Pressure control and meter.
Don't see any evidence of digging. I can imagine that they were doing pigging work, opened a pig receiving barrel and did not allow enough time for residual gas to escape. Maybe a truck too close because of not wanting to walk too far in the rain, ignited the gas around the open barrel. One big boom, no continuous fire. 2 dead, 2 injured and some more laundry to hang out after the rain stops at the house next door.
Have to wait and see if anything more develops or until DOT/PHMSA tell us something.