Structural Design of laterally loaded piles.

[RESENG2]

2 story house on the beach. 120/C/Enclosed.
F.F. @ 18' (based on BFE)
E.G. @ 9'
Scour to 5.5'
Using the Coastal Construction Manual, point if fixity is 8.5' below the localized pile scour (2'-8" based on 2x the diameter of a 16" pile).
So that leaves me with a 23'-3" cantilevered pile. I ran my design and I am coming up with a 24" diameter pile w/ (12) #7's.
The builder I am doing this for built a house a few houses down (same grade/scour/etc.) and the previous engineer specified a 14" dia. pile with (6) #6 verticals.
So now I'm scratching my head. Either the previous engineer did not design for any flood loading which is much greater that the lateral wind load, or he assumed the column to be fixed at the top or even fixed at the scour depth (thus the column being ~11' shorter).
My question is, am I correct to assume the column is not fixed at the top? The floor system will tie in ~50 piles supporting the floor beams.
I DON'T WANT TO BE THE "OVERKILL ENGINEER"!!
Any suggestions would be greatly appreciated. Heck, requests of consultation fees for quality feedback would even be considered.

 

[civilperson]

Design for fixity at the top of the pile with L bars, cost effective way to decrease "k". All concrete is not equal (5 ksi vs 3.5 ksi), the number of smaller piles may be larger than the number of your larger diameter piles for equal resistance to lateral forces. Scour maybe prevented with large riprap with concrete infill, (or reinforced pavement with turndowns). Comparison is educational but not productive!