Hazardous drain water on Clean Class Drillship. How to get rid of clean rain water?

[Swedishrigpig]

Just came out of the Shipyard with a brand new drillship and DNV has a Clean Class which basically means all rainwater goes into a tank with a 10m3/hr Oily Water Separator.
This is of course not enough to handle the massive amount of rain and we are wondering if there is a legal way to deviate the clean water straight overboard?
What we get now is draining the clean water into a dirty oily tank and no way to empty it fast enough.
We have been lucky not to get a lot of rain but one day we might not so lucky.

 

[BrianBT]

Sir,

I have never heard of collecting rain water before on any ship. I cannot imagine its relevance to CLean Class notation as well which is more about environmental impact.

On tankers during cargo ops you may have scupper plus in which are periodically removed to drain off rain water so that any oil lossis contained in the bunding and does not overspill.

Who is asking you to trap rain water?

 

[chicopee]

By the name of the author of this OP, it seems that he or she is from Sweden and Sweden is very very Green on pollution issues, so may be there is some Swedish regulations stating only clean rain water can be disposed overboard. I think that the author is thinking about bildge water which is another matter all together for ships.