Merging Two Different Designs for Seawater Intake

[jmas]

To set forth my questions it is necessary to have some history. The story is that our company at first won only power generation unit of whole plant, which encompassed once-through cooling system with its own design for seawater intake. After a while we won Desalination system of the plant which has its own design for seawater intake. At this moment, Client asked us to join these two separate sea water intakes into a unique system. The differences between two designs are numerated but those I am willing to bring to discussion with you are:
1- Once-through cooling pumps are Dry-pit type, but Desalination system pumps are Wet-pit type (see attached file).
2- Discharge of Once-through cooling pumps going out of intake concrete structure via underground GRP pipes, but in Desalination system configuration the outlet piping is aboveground and after some meters it will go underground.

So, I should be grateful to have your advice for selecting one of the sides, considering following opinions from me:
a- Wet pit design requires more earth excavation (because of min. required depth of water), but dry pit needs a FSI (Formed Suction Intake), which in turn required more money.
b- I think going underground directly, may cause scissoring forces in GRPs which are weak in shear (due to settlement of concrete intake structure).