Underground Drainage Help - Downpipe Rainwater into which gully?

[ltfcstew]

Evening all,

Just finishing off an extension and the groundworks guy left me a T-junction running to the soakaway for me to connect to a gully to take a rainwater downpipe. I think I have two options but am not sure which one:

OPTION A:
Fit a gully setup like this sat in some pea shingle with the rainwater pipe running over it and then into the soakaway... job done:

Or OPTION B:
Alternatively do I need a contraption like this which will hold water and therefore stop any foul smells coming back up the pipe. It's only rainwater and a land-drain going to this soakaway - so no waste pipes - so not sure how many smells there will be.

This is likely a very easy answer for some of you - so apologies for being dim! Any help would be ace. So basically do I need a trap for rainwater really.

Thanks in advance!
Stew

 

[lostinthelight]

personally I would use B so any sediment is trapped instead of maybe blocking the soakaway over time.
litl