I'm a nuclear engineering student down at the University of New Mexico.  We are currently working on a design project for a steam distribution system.  The project involves replacing the steam piping between 2 boilers and 7 buildings.  My project is located in Worcester, MA.  I'm wondering how much would it cost for a crew to weld 37,000 ft of 24"Sch40, 15,000ft of 18"Sch40, 22 gate valves, and 13 slip expansion joints.

I don't need an exact number, but a rough estimate would be great since I have no idea how long or how many people would be needed.  I would assume that I would need 2-3 crews (to get the job done within 6 months), and I think each crew would consist of:
1 heavy equipment operator (to move the pipe from the rail cars to where they will be welding.
2 welders (figure one to weld one to make sure it's going ok)
2 guys/gals to work on the pipe hangers.

A supervisor to watch it all and probably a couple apprentices to help.

So I figure about 15-20 guys, but I don't know how long it would take.  If you happen to have a quick thumb rule for time needed per ft of pipe and a rough cost for a crew I would really appreciate it.

Thank you for your time,

Jim