If you're talking about large diameter drain pipe (the big, courrugated stuff), yeah that would make an excellent pump vault. Lots of holes or big slots for adequate water flow.
General guideline for intake bay design is 1 gallon of water in the bay for every gallon per minute.
Example: 3000 gph pump = 50 gpm = 50 gallons of water needed in the bay for the pump to draw without restriction. 50 gallons = 7 cubic feet of water.
You can get that 7 cubic feet however you like. An empty 4x3 bay (all water) would be plenty big enough at less than 1' deep, but then you'd have no pre-filter for your pump and it wold clog up.
You could fill the whole bay with gravel, but then you'd need to go 2' deep, and you'd risk getting deep clogs that need difficult maintenance.
If you use aquablox, milk crates, more drain tile, or other suitable materials to create a void space that can support gravel on top, then you get the best of both worlds. The shallow gravel is a good prefilter for your pump, and the bay can be kept smaller because most of it is void space underneath.
Post some pics of your build. Would love to see it.