Spoke to the Storm water engineer yesterday and after a bit of checking he said that if we raised the Garage level to 34.1 then we would not need the transpiration pit in the backyard (that also means we don't need all the pipes going to it).
So not knowing anything about levels in houses I duly wrote it down and rang our sales person. We looked at the drawings and at the moment the garage level is at 33.78 so it looked to me that it wasn't that much of a difference (you know how you become a expert as soon as you start doing something or watching something, think of the Olympics!!!!)
It looks like they will have to push a bit more dirt to the front of the house to bring it up a bit so that the water can run back to the street.
We may need a drop edge beam if this happens, (I think that's what its called) so we are waiting on costings , hopefully we will have it today.