I have a customer with a a 20 year old inground pool, they no longer use. They want to fill it & install a patio. The pool fill in is eay part, not quite shure what to use as fill so it won't settle (41/2 ft deep). Obviously we will have to compact in lifts 3-6" at a time. Thinking it may be best to use 2" crusher run (driveway base), for complete fill in. Any ideas & imput would be appreciated, this is a new one for me.