A friend is having his pool redone. He said the company that will be doing the work told him the pipe under the concrete around the pool will have to be pressurized when they pour the new slabs around the pool (Flat work) so they don't collapse, for an extra $700. Being a retired plumber/pipe fitter, I just don’t believe this or have ever seen it done on any job. I have seen pipes in ditches filled with water so if the ditch fills with water the pipes won’t float up. (ditches not backfilled) Any thoughts on this pressurizing the pipe? BTW I told him to join this group to learn about pool start up