Sunoco is proposing a new plan for the segment of the Dragonpipe (Mariner East pipeline system) that runs by Lisa Drive, in Exton, where there have been ongoing sinkhole problems. The 16-inch pipe is already in the ground there, and this is the plan that Sunoco has submitted to the Department of Environmental Protection for the companion 20-inch pipe.
This blog post will describe the issues that concern me most about Sunoco’s plan, and at the end are instructions for submitting comments. You can read the plan in its entirety here.
Is this use of “direct bore” technology safe? Sunoco plans to place the pipe using “direct bore” technology (also known as “micro-tunneling”) for a stretch of 816 feet (the balance being open trench). The direct bore segment runs under the Route 30 bypass, a pair of wetlands, and the Amtrak line.
Direct bore is a horizontal tunneling method. It differs from horizontal direction drilling (HDD), used previously at this location, in that there is no pilot hole. (With HDD, a small pilot hole is drilled first, and then it is enlarged to the desired size.) The direct-bore tunnel is drilled at its finished size right from the start, and a casing (a large support pipe) is pushed in right behind the drill as it advances. After completion of the drill, the pipeline that will actually be used (the 20-inch ME2 pipe in this case) is pulled through the casing.
The direct bore approach is safer than HDD in the sense that it protects the surrounding ground from collapsing into the borehole. Fair enough.
But it is far riskier because it uses no pilot hole. The very large drill is not really steerable, and it can drift or be deflected by local variations in rock hardness. The drill will be really massive: the proposed casing is a 42-inch pipe. The drill will have to be larger still—around four feet in diameter.
For at least part of this segment, the drill will be in close proximity to two active NGL lines: the original 8-inch ME1 and the 12-inch “bypass” line. How will those lines be protected from the drill? Does Sunoco even know their exact location underground? (After all, both of them were buried in the 1930s by companies long since out of business.)
Those lines show up on the plans in Sunoco’s document, but they are never mentioned. Each crosses the planned route of the 20-inch line at least once. Isn’t this an invitation for disaster?
The 16-inch pipeline also runs along the same route as ME1, but it is much deeper, having been installed using HDD, so its route does not conflict.
When you comment, tell the DEP that the direct-bore approach is too big a risk to the other pipelines in this easement.
Why wasn’t the most obvious alternative route even considered? Sunoco was required to consider alternative routes in this plan. It does not really do so, but simply refers back to its original pre-construction application, which claims there is no “practicable” alternative. It does mention the right-of-way of the nearby “Texas Eastern” pipeline (which hasn’t actually been owned by that company for many years) and dismisses it, saying it “presents no advantages”.
What astonishes me, though, is the apparent failure to assess the route of Sunoco’s own 12-inch “bypass” pipeline. North of the Amtrak railroad tracks, this follows essentially the same path as ME1. But south of the tracks, it veers off to the east and then follows Ship Road to the south, later rejoining the ME1 route. This route avoids the spot where all the Lisa Drive sinkhole problems were, and it also avoids passing through the heart of the residential neighborhoods south of Lisa Drive. Why was it not considered?
Why the 12-inch route isn’t mentioned as an alternative in Sunoco’s plan is beyond me. Is it because Sunoco wants to downplay the presence of another active pipeline in the area? Or is it because the person preparing the document didn’t even know the company had another pipeline in the vicinity? Or didn’t know that it took a different route through this neighborhood? It’s a real head-scratcher, and it doesn’t speak well for the level of care that went into this document.
When you comment, tell the DEP that Sunoco needs take seriously the requirement for examining alternative routes. Why didn’t the company even consider its own nearby route?
Will this approach protect against frac-outs and sinkholes, as claimed? Sunoco blithely claims that the direct-bore approach “represents no risk for an IR” [inadvertent return, or frac-out] because of the use of a casing. But that’s simply not true. Articles about this method in trade journals offer advice about minimizing frac-outs, so clearly they are a problem.
And I see no reason to believe that pushing this massive drill through the earth at Lisa Drive would not have the potential for triggering another sinkhole as well. We came close to a disaster with the previous sinkholes at that site, and it should not be risked again. In the document, Sunoco claims “the risk of subsidence is greatly reduced” compared with HDD. It may be reduced, but it certainly isn’t eliminated.
When you comment, tell the DEP that risking more sinkholes is unacceptable.
Let the DEP know what you think! This plan has the potential to damage active pipelines and open new sinkholes. An obvious alternative route hasn’t even been considered. Tell the DEP that Sunoco should be required to do better. Please submit your comments immediately. Feel free to make use of the information in this blog post in the comments you submit. But it is more effective if you use your own wording rather than simply copying mine. The DEP needs to hear from you!
Email your comments to: Raemail@example.com
Mention the ID number for this section of the pipeline, which is S3-0400. The deadline is this Thursday, June 13 (that’s tomorrow, if you’re reading this on Wednesday).
While you’re at it, why not copy your local state representative and senator? They need to hear your opinion too.