+1 on contacting that NRA - they have advisors who can help you with planning and other issues.
If you're interested in building a larger range, such as 1000yds, you should also contact Dick Whiting. I think that Dick had developed many of the materials for the NRA.
PO Box 4538
Bridgeport, WV 26330
You can find his info here..
He's extremely knowledgeable, well contected, and very interested in seeing to it that new ranges are developed in the US.