[Pontiac]

There’s a difference between a leaking pipe and a tunnel that is caving in.

The immediate problem seems to be that the tunnel lining is failing and restricting flow. From the article.

The risk right now is that the tunnel lining could continue to fail and, at some point, that might restrict our ability to get flow through it.

I believe the process I linked to could be a solution to the problem. At least for ten years or so until a new tunnel could be built.

[DB]

It depends on the cause of the lining failure. If the lining is simply leaking causing things to soften and cave in then you are probably correct. If it is the earth surrounding the lining crushing the lining, not so much.

[DH]

At least for ten years or so until a new tunnel could be built.

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Hell! That’s how long the environmental studies would take before any physical work could begin.

The whole thing just might be cancelled due to the discovery of the wooly maggot or the 8 toed grasshopper.