I'm doing the right think and waiting for the survey. I was just interested how they figured the FFE. I looked at the plan closer, this is what it st...

Correct, the benchmark on the manhole is 3.50 (yes, close to the coast)FEMA requires 7.0 NAVD where I am located. Should be 17-20 feet for FF. How do...

Yes, the elevation has to be at 7.0'. The benchmark is 3.50'So if I undersatnd correctly, just subtract 7.0 -3.50. FFE is 7.0'

Understood, that is what they are doing. I just want to know how it is figured.