+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.
Dick Whiting
PO Box 4538
Bridgeport, WV 26330
304-842-9035
You can find his info here..
http://www.rangeinfo.org/
He's extremely knowledgeable, well contected, and very interested in seeing to it that new ranges are developed in the US.