Unless you have had experience in designing and building things from concrete- don't. No, really- don't.
First, if this is below grade, you will need a means of controlling ground water drainage- and a LOT of dirt to move (3x3x3 of soil is about 3000 lbs). You will need to keep your excavation from collapsing while working inside it (sloping or benching the earthen sides)
Concrete comes in different strength mixes- the 3000 lb concrete that works good for sidewalks will not cut it. You will need steel rebar for reinforcement. Design will need to support weight of concrete + weight of soil over it. Forms must be substantial and supported, or you WILL blow out a form. Concrete is HEAVY- and wet concrete is caustic- will eat the skin off you.
There ARE prefab concrete and/or metal structures. If you can lay block you may be able to build your own structure, but again, you will need a design (and possibly building plans)
PS- Gunite maxes at around 4,000 PSI compressive strength- usually a lot lower. Concrete can run up to 10,000, and work with some specialty stuff even higher, but $$$
Oh- burying a shipping container- walls of container have no support against a load applied at a right angle to the sides. Walls will bow in under pressure, and then fail. Walls would need design to resist that load.
What we have here is... failure- to communicate.
Last edited by c3shooter; 02-24-2013 at 12:39 AM.