Without knowing all that may be down there and what sort of protection is in place, what they plan on doing from the electrical stand point sounds very reasonable. I have seen situations below grade where when things were first installed they were properly protected but over time the protection has corroded away. It sounds like on one hand they are over killing things, but on the other they sound smart and anticipate possible problems. I think they could decide the mats are overkill once in and determinimng the site safe.
This all assumes you mean 7.2kv (7200 volts) and not 7.2 kev (7200 electron volts) which I am sure is less than the voltage that is created by air flow through my nose when I sneeze.
There are additional OSHA confined space entry requirements and permits (at least for us in the Government) dealing with oversight, rescue ect. We have training on it, but it has been some time since I took it (I am not typically involved).
Sorry that I can not give you better information. I hope that this at least gives you a place to start and those more knowledgable step in to help.
