Well, in principle it took a lot of material to build one of the big revetments. I read some where that it took somthing about many thousands of 5 gallon tanks to build a single revetment for Wellingtons in Malta!
It is perhaps better to stay low on polycount using simple shape and use the texture as a "proxy" to get the effect of many tanks.
Coming back to the previous model, here is a comparison between new and old:
and how two revemetments can be combined:
