posted on Jan, 2 2011 @ 09:28 PM
If the question is referring to the grid like structure against the wall that looks like it leads to underground, it could be for storm water
retention. Desert rain is infrequent but really hard when it does come down. By retaining storm water, you reduce the surge, and thus less erosion.
Just a guess mind you. The photo isn't that good.
storm water retention
The Army Corp of Engineers requires a SWPP. (Storm Water Polution Prevention)
If you look at the roads around the Nellis range, there are all sorts of culverts to handle the rain. Some places the culverts are so big you think
you are on a road, well until the culvert ends. ;-)