Passive screening for seawater application

Hi All

What is the efficiency of air blast cleaning operation for passive screen for seawater intake piping? 

In my opinion, passive screening works well for river water application as compared to seawater application. 

Regular air blast is also opex intensive, specially for pipes which are more than 1.5 kilometers in length; designing a system for 8 - 9 bar pressure for 1.5 kilometre length is a difficult ask.

Please let me know your thoughts on O & M of seawater intake pipe, 2.2 meter diameters, 1.8 kilometres in length, having passive screens (as opposed to open intake structure).