Based on national statistics from the National Safety Council, we know a lot about the risk of accidental death.
If I were a safety official in a town of 10,000, for example, I could look up the odds of death from various causes, and I would learn that (based on my town’s population) there is likely to be about one death from a fire every three years, one swimming–pool drowning every 50 years, and one death from lightning every 1,400 years.
These are national statistics, of course, and the conditions in my town may be different, but I could still get a sense of where my priorities should lie as a public safety official. I could tell that I need to worry a lot about fires, a little about swimming pools, and I can basically ignore lightning risk.
But what are the odds of death caused by the explosion of a set of pipelines like the Dragonpipe (Mariner East 2 pipeline) and its older sibling, Mariner East 1? Are we talking about a substantial risk (similar to house fires) or a negligible risk (similar to lightning)?
The statistics from the National Safety Council can’t tell us that, but it is not impossible to figure it out. There is a discipline called “risk analysis” that has well-established procedures for exactly this type of situation.
Probability and consequences. Two factors go into a risk analysis: the probability (or likelihood) of an event, and the consequences (or losses caused by the event). Mariner East is actually the combination of three pipelines running in the same right-of-way: the existing 8-inch pipeline called Mariner East 1 and the two that are under construction, called ME2 and ME2x. For these pipelines, the probability of a leak can be determined based on the history of comparable pipelines elsewhere. Similarly, there is enough data from previous pipeline accidents to estimate the consequences.
Using those two factors—probability and consequences—it is possible to estimate the annual risk of death for an individual who lives at a given distance from the pipeline. That’s the starting point for all pipeline risk analysis.
That calculation is based on a combination of the engineering details of the pipeline, the physics of the gases released, and estimates of factors such as size of leak, wind velocity, and the time it takes for the gases to find an ignition source. By trying different values for those variables, the analyst can determine the probability of a death from an explosion for a person at a specific distance.
From individual risk to group risk. The next step is applying the calculation about individual risk to larger groups. Thanks to the US Census, we can find out how many people live at different distances from the pipeline. That allows the calculation of the combined risk for everyone in a given town, or of everyone along the whole length of the pipeline.
This type of risk analysis is exactly what State Senator Dinniman proposed when he launched the fundraising drive for the “Citizen’s Risk Assessment”. It is also what the Delaware County Council is proposing to undertake, on a more limited scale. There are well-established companies in the business of doing these pipeline risk analyses, and they have been sent requests for proposals by both groups within the last few weeks.
Both of those studies, assuming they are completed, will provide much-needed guidance to emergency-response officials, town planning officials, home buyers, and the general public.
Sunoco knows, but they’re not telling. Apparently, Sunoco has already done this kind of risk assessment. They have even shown some of the reports to some town officials, but only after the officials have been sworn to secrecy and have been prevented from taking notes or otherwise recording the data. At least, that’s what I hear. I haven’t seen the reports myself, and I haven’t spoken to anyone who is willing to confirm that they have seen them.
But a glimpse of some Sunoco reports by a few officials is not enough. It is critical that this information be made public. A risk is being imposed on local residents without their consent. If it turns out that the pipeline risk is miniscule—the equivalent of lightning strikes—I will stop worrying, and I will encourage others to relax. But I’m afraid it’s much worse than that, and I won’t be satisfied until I see a real risk analysis.