Capping for PAZ combined wall system

[Awre]

I am looking for RC capping options for a PAZ combined steel sheet pile wall. The piles are about 1.5 m in diameter with 2 AZ-26 sheet pile in between. Since this would be on the water one of the options is to drop the face of the cap in front of the wall system to the water level which is about 4 meters below the top to provide additional protection as well as flat surface. I am thinking about both cast-in-place or precast options.
Is there any typical details for both options; cast-in-place and as a pre-cast?
I would say, the cap will be as wide as ~2.5 meters or so to cover the top of the wall plus the 4 meter drop in front. typical details are appreciated.. Thanks