Not all climate engineering concepts are completely daft. Seding the atmosphere with Sulphur as an example (the Annunaki knew it must be Gold, to be effective).
The environmental pitch is that it would lower the Ocean's level 3mm. It's more likely the resorts on the Eastern shore would be the gating factor.
The Boring Company found a 10x reduction in tunneling costs. The Plasma Torch people will undercut them. 60km times four at 1km a day (x4?) means it could happen pretty fast.
.....once the relevant authorities sign off.
This is similar in scope to M. al-Qaddafi's Underground River that was destroyed.