MH refinery (Imperia) 11-16-19

In the early morning hours of November 9, 2019, a series of “booming”sounds occurred in Sunoco’s Marcus Hook refinery. They were reported from a distance of several miles and were discussed on social media by dozens of residents of the area. The noise went on for about three hours.

We now know, thanks to persistent work by a nearby resident who lives across the state line in Delaware, that these were explosions of vented gas within a Sunoco flare tower, similar to the one that occurred at Boot Road in August. The explosions (also variously reported as “loud rumblings” and “loud pulsing/thumping sounds”) were a result of the failure of several safety valves. An inquiry that was sent to a local state representative, and passed on to the Delaware Department of Natural Resources and Environmental Control (DNREC), brought this response from DNREC:

“Per Sunoco the cause of the flaring was that there was freezing in several instrument air lines that control safety valves to different pieces of equipment.  Upon freezing the valves position was not regulated so they failed to open, which results in gases being sent to the flare.  This is a safety measure to prevent a release and avoid over pressure in vessels.  The facility is working on identifying other areas where this could occur to address the moisture/freezing conditions.”

Let’s take a closer look at what this means. If there are “air lines that control safety valves”, this implies the valves are pneumatically controlled. Frozen water in the air lines blocked air movement, and the valves failed to open when they should have. There is no indication of what equipment and what products were involved.

The explosions took place inside the flare tower. That’s a good thing. If they had been in the open, the consequences could have been severe.

On the other hand, having safety valves in a refinery fail is a matter of great concern. I am not reassured that “the facility is working on identifying other areas where this could occur.” This suggests that some really sloppy design or construction work may have occurred in this refinery.

And then there’s the matter of water freezing in “air lines that control safety valves”. Moisture somehow got into multiple air lines, and froze there. November 9 was an unusually cold day. According to AccuWeather, the temperature at the airport got down to 30 degrees in the early hours, the first below-freezing temperatures of the fall. So perhaps this was an accident that was just waiting for a cold day to come along.

Or perhaps this was a consequence of the “modifications to … Marcus Hook to enhance the reliability of the system and allow for improved flows through the facility” that Energy Transfer mentioned in their latest quarterly earnings call. ME1 was shut down for several weeks in October for that work. This company has a history of rushing construction projects in an effort to get pipelines running. Could that have happened here? It certainly happened in the Beaver County explosion last September.

Could this be related to the strange odors in southern Delaware County? We don’t yet know whether the explosions on November 9 could have any connection with the smells that have been coming from that area in recent months, and especially the releases on October 25 and November 11. It’s certainly possible. We don’t know what products were involved in the explosions, whether those products could produce odors consistent with those reported, and whether there were other (presumably smaller) releases in the period before and after the explosions.

These are questions that need to be investigated by a third party such as PHMSA. And Sunoco needs to be forthcoming with the details of what it has actually been doing in Marcus Hook. Until now there has been no public explanation for sounds that startled a large number of local residents from their sleep. Sunoco’s secrecy is putting our lives at risk.

In fact, the limited account of valve failure that we have from DNREC brings up all sorts of other questions. Might Sunoco have been dealing with a difficult-to-diagnose equipment problem for months? Might water in the air lines have caused problems with the safety valves long before the freezing episode? Might that have resulted in odor-producing emissions but not explosions? Might it have taken an episode of freezing weather to pinpoint the source of the trouble? This is all speculation, of course, but it deserves to be checked out, given the mysterious odors.

Delaware residents: here’s how to get involved. The Sunoco Marcus Hook facility straddles the Pennsylvania-Delaware line, so Delaware residents (especially those in Claymont and the surrounding towns) are also threatened by problems at Marcus Hook. You might want to join the new Delaware-based pipeline safety group that is just getting started: Delawareans for Environmental Safety (DES). For information, contact (Note the name and email change from previous versions of this post.) A Facebook page is coming soon.