Correct prep for natural gas line extension?

I want to extend my natural gas beyond the house to a shed with my pool heater in it. I will hire a qualified plummer but I want to do as much prep as I can and I want to be as knowlegable about the process as I can. I will be coming out of a crawl space and going directly underground at that point, 30' across a storage area, a 90 degree turn and about another 12' to the point where I will come up next to the shed. Should I put in something like a 2" pvc with street sweeps and have plastic placed in that or the stainless flex? or wrapped black pipe? If I use plastic, how does it make the transition to pipe for the risers? I had planned a shut off at both buildings. The storage area will have concrete poured over it so I want to get it right.
Thanks!

The first step of the correct prep is to talk to the guy who will be installing the gas line. You might get 5 perfectly good answers here, but the person qualified to install the gas pipe might reject all of them.

I was hoping to get the prep work done so I can get concrete down before winter and probably not get the gas work completed until next spring.

I swear to god fellas, on me poor sainted mothers grave that this one is not me.

nhmaster, class clown?

nhmaster, I see by looking at some of your other posts you consider yourself a very funny fellow.
thanks all for the help... I'll look elsewhere

Oh boy! Maybe a better reply would have helped.
The planning sounds faulty!

gas

IF you are going to pour concrete over the gas line, you have a very complicated installation and you MUST have the eventual installer do the preliminary work. It will have to be inside a sealed sleeve with an atmospheric vent. Depending on which material he uses, it may have to be installed at the same time the sleeve is constructed. Even the terminations at each end can be problematical for your situation.

Inside Joke. You need a copy of the National Fuel gas Code book, chapter 7 along with a visit to the code official & the gas utility company. At this stage of your project and if fact throughout the entire phase, the only thing that you will be able to do is dig the trench. It must be at least 12" deep with a 6" bed of sand, no big or sharp rocks. Then the plumber will handle the permitting and inspection process which if like our town requires inspection by the city and finally the utility. Choice of materials will be left up to the utility company ususally.

gas

Here, the plumber decides on the material, and if it is PE, which is most common except for very short runs, it has to be 20" deep.