TP,
Thanks for the informative reply...
The reason for my question is because The Grove, recently designed by Kyle Philips in Watford England, and soon to be the site of the WGC Event later this year, has a 17th hole with a similar feature to the left hand side, short of the green.
The feature is by no means as big as that at FH, but behind the large mound, (completely blind) is a significant swale which is 2m? below the level of the green.
From the fairway it looks like the mound flanks the green but in fact, it is essentially a double hazard. You hit over the top thinking youll be on the green but in fact you have a high chance of being in the bottom of the swale.
An excellent use of a large mound!