Rainwater downpipe gullies and rodding points to soakaway

[Spinny]

I have two rainwater downpipes running down from extension roof to be connected into pipe runs to a soakaway. Both downpipes are located at internal corners on the outside of the building. I have been shown standard bottle gullies which provide a water trap but cleaning or access for rodding seems a problem. I also see there are alternative gullies for downpipes which have a leaf catcher built in and a removal cover to clean, however they do not have a water trap to stop odour - is this something I should worry about ? What do people usually do for downpipe gullies to a soakaway (I am putting a silt trap in at the soakaway) ?

[Russell griffiths]

You do not need a water trap if the pipes run to a soakaway. You will not have any odour from a soakaway. 
you only get odour from a foul sewer. 

[dpmiller]

you might need a trap if there are LPG cylinders in the locality

[saveasteading]

It is worth detailing to stop leaves and muck getting to the soakaway.

 

Having the downpipes outlet onto  grilled hoppers is standard.