So they put big metal posts in at 45 degrees facing up the hill to catch the big branches before they get to the drain.
It seemed to work (we just have to call the council to clean out the channel after a big fall.
Just as background our backyard is adjacent to natural bushland that is adjacent to Mt Whitfield Conservation Park
The 'flooding' is caused when the first rain of the wet season washes all the bush detritus (tree branches, dead animals, fecies, general flora) that's built up in the dry down the hill. If the first rains aren't to big it's an orderly process and won't block the drain, if a big rain comes after smaller rains have moved most of the detritus it isn't an issue. The problem is when there's a lot of detritus and a big rain, the detritus catches in the drain cover slows down the waterflow into the drain and the water courses sideways through our yards.
Anyway the engineer solution I mentioned seemed to work - until early this February.
Where this timeline of events happened.
7:30 am Hinge about to leave for work, and phone rings. Caller ID says it's my neighbour up the hill. Can't hear.
7:31 Phone rings again - caller ID doesn't recognise number. It's neighbours wife (using landline) - come quickly the drain is blocked.
7:32 Hinge has stripped off work clothes and is in shorts and singlet and thongs entering neighbour's backyard (they have a gate in their back fence to access the drain - my fence backs onto the easement (and has no access to the drain)
Their backyard is knee deep in brown water and my thongs keep coming off as I head to the drain. Get to the gate and neighbour and his adult daughter are waste deep in the concrete channel to the draining pulling branches and other detritus out an throwing it on the downhill side of the drain, I jump in and help.
8:30 we finally have water flowing into the drain at a steady pace and we're soaked, exhausted and only just thinking whether we have melioidosis.
Neighbour explains that the whole family was on their second floor deck having breakfast when they saw the water start flowining into the backyard and they knew the drain must have blocked again.
If the timing had have been at any other time (when they weren't on the deck, or I wasn't home) we would have gone under again (Mrs Hinge told me when I got back that the water was lapping at the lowest entry into the house again - I could see the waterline left by leaves and dirt and it's hard to believe it didn't get into the house.
Anyway we're dragging the engineer in again - but I don't have any before photos for him this time.