There were major problems with Sunoco’s first HDD at Pennsylvania Drive, in Chester County, on the border between Uwchlan and Upper Uwchlan. During that process, there were multiple frac-outs and, most disturbingly, a huge sinkhole that could have threatened the active 8-inch pipe running in the same right-of-way. Now, the company wants to do a second HDD at that site.
You can help prevent major problems at this site by emailing the DEP by tomorrow, May 5. You will find directions for doing so at the end of this post.
There are multiple problems with this proposed HDD, but I will focus on just two: the unstable geology of the ground in the area, and the question of what happens when the casing (in which the pipe is to be installed) is removed. These two questions are interrelated (because unstable ground might collapse if the casing is removed) and they are the questions that the DEP is most interested in, based on their responses to Sunoco.
You can read Sunoco’s proposal and the various responses to it on the DEP’s HDD Reevaluation page. Scroll down to the final entry in the table and click on the various underlined links.
The issues were raised in earlier public comments. In the first public comment period, ending February 18, the two issues noted above (among others) were brought up in comments from Mountain Watershed, the Delaware Riverkeeper, and the Clean Air Council. They noted: “While drilling to install the 16-inch line at the Site, Sunoco created a massive, 25 ft. x 20 ft. x 30 ft. sinkhole. … Nothing in the Report as submitted suggests that drilling of the 20- inch line will not result in another sinkhole.… According to Sunoco, the existing, operational 8-inch line that runs through the Site was not exposed by the first sinkhole. But it was only a few yards away. The next sinkhole could expose or otherwise disrupt or destabilize the 8-inch pipe, the newly installed 16-inch pipe, or one of the several public water or sewer lines that crisscrosses the proposed alignment. Sunoco must fully address this significant risk.”
On February 26, the DEP’s Richard Staron wrote to Nick Bryan of Energy Transfer (Sunoco’s parent), highlighting ground stability issues including the casing problem: “If [the casing is] temporary, an explanation will be required demonstrating how the overburden will be stabilized in the absence of the casing.”
No answer to the stability issue. On March 5, Monica Styles of ET responded. She avoided directly answering the casing-related question. Styles wrote, “ET’s intent is to remove the casings, following completion of the construction of the 20” pipeline, where possible. This determination, however, can only be made after the pipe is completely installed and the area around the casings is evaluated for but not limited to: 1) post pipe pull subsidence inspections around the casing locations, 2) review of any issues encountered during the pipe pull (i.e. groundwater flowback) 3) ability to pull the casing without adverse effect to the installed pipe 4) the logistics and effectiveness of providing suitable replacement materials (such as backfill soils or grout) following the casing removal.”
None of Styles’ answers addresses the DEP’s request, which was “an explanation … demonstrating how the overburden will be stabilized in the absence of the casing.”
- Answer #1 just addresses the situation before the casing is removed, not “in the absence of the casing.”
- Answer #2 speaks to “groundwater flowback” but not the stability of the ground without the casing.
- Answer #3 addresses whether the pipe would be damaged by pulling back the casing (and it doesn’t say how that assessment would be done) but it does not mention the resulting situation “in the absence of the casing.”
- Answer #4 tells ways that a sinkhole could be filled if one is created, but it fails to address the question of stabilizing the soil to prevent such an event, which could trigger a catastrophe.
Meanwhile, Sunoco finally released the geophysical testing report for this site (which it had earlier refused to make public, claiming it was “Confidential Security Information, which of course, it was not). The report is embarrassing for Sunoco, though, because it covers the area where the previous pipe is already in the ground, instead of covering the area where the new HDD will take place.
Neither Styles’ memo nor the geophysical report really addresses the ground stability issue or Sunoco’s plans to deal with it. Either Sunoco is not willing to say what it plans to do about the possibility of another sinkhole, or it may have no plan at all.
What to write: insist on a response to the stabilization issue. Tell the DEP to insist that Sunoco must directly address the question of stabilizing the soil to prevent another sinkhole when performing the HDD and when the casing is pulled back.
Write to the DEP at this address:
Tell them not to issue a permit for the HDD at Pennsylvania Drive until this issue is resolved and the public has a chance to comment on Sunoco’s response.
Time is of the essence: the deadline for you to submit comments is May 5.