Ben,
Don't forget to have them waterproof both sides of the weir wall. They may try to tell you its not necessary but it is.
Vanishing edges look beautiful, but construction problems can happen all too easily. Check out these common trouble spots and how to avoid them.
aquamagazine.com
Use the link above and it will explain it. There was some questioning when I asked STP to do it but they agreed in the end. Also make sure that they provide an overfill (because of rain) drain line for the catch basin and I would suggest a autofill feature in the catch basin also. Your overfill drain line could go directly to the Bay.