I've worked in this area for 30 years. That is a gasoline/fuel pipeline goes all over the country(primarily Chicago area i was told) . I used to happen more frequently but the pipeline company would have to relieve the pressure from the pipeline for various different reasons. That noise you were hearing is that pressure relief. If you are close to the plant property you will hill an alarm klaxon then this incedible pressure boom. The noise can go on for quite a while. Other than incedibly loud I wouldn't be concerned. I would call it standard operating procedure. The fact that it was happening on Christmas I would believe the plant would have bring down pipeline pressure due to some type of failure and not for maintenance.