Ann: Diggers and Dealers Presentation August 2018, page-14

Companies propose having processing off lake.
RWD notes in its PFS that trenches and access roads will have a 550mm flood protection system (shown in a diagram). I assume AMN will do something similar.
Companies will clearly have to protect trenches from the most likely flood levels but I doubt they will be able to protect from all events.
Note that some surface water run off is critical to recharging the resource.
Clearly it is desirable to have less trench to protect. Grade is important.