The pipe to the soakaway for one of our gutters is choked-up with leaf mold and general crud. I've rodded-ed it but suspect that the soakaway itself is gunged-up so am tempted to dig it out and replace it with a pre-fabricated plastic one; especially as student labour is around at the moment ;-)
Presumably the necessary volume can be calculated from the roof area and type of soil - but how?
Dave