When you say "2 pass program of glyphosate", what exactly are you saying?  Are you saying 2 passes of glyphosate and no other chemistry?  or are you saying a residual pre-emergence followed by glyphosate in the 2nd application? 

If you answer is the first, I can understand why you are having difficulties making that work.  We don't deal with waterhemp here;  however, based on what I read here, about how bad waterhemp is,  it's just craziness NOT to include some kind of residual program if you are dealing with waterhemp. 

At one time,  a glyphosate program worked, or appeared to work. However,  we are now seeing the problem of that kind of program - resistant weeds.  We, as an industry, need to get away from the idea of 1-chemistry-only programs.  They are a recipe for problems.