Warrandyte is a very hilly area, and my house is near the crest of a hill so even heavy downpours simply flow away from us. See exhibit A to the left.
Thanks to my poor photography, the land in the photo looks flat, but it’s actually very steep. If you click on the photo you will see a much larger version in which you can just see the roof of the house down the bottom of my block. That should give you some idea of the actual lay of the land.
Unfortunately, even a well-placed block cannot compensate for owner stupidity [mine]. Explaining what I did wrong will require a few more pictures :
This first photo is of the area leading to my firefighting pumps. To protect them, I had a pump-house built. Nothing wrong with that. To further protect them I had a wall built in front of the pump-house with an earth berm on the other side [the idea is that fire will rush up the hill and be deflected over the pump-house]. Also not a bad idea, especially as I had an ‘agi’ pipe laid to carry away any water that might flow into the pump-house area.
So what went wrong?
Well, late last year I had this idea of laying flat paving type stones in front of the the pump-house. My reasoning was sound; every north wind deposited heaps of eucalyptus leaves and branches in front of the pump-house. This debris was not only a potential hazard during a fire but also a real pain to clear. [I’d originally covered the ground in a layer of big pebbles, and you can’t sweep pebbles].
Long story short, I thought the drainage in the area would not be affected if I simply placed paving stones on a thin bed of sand…
I was right, and I was wrong. Light showers drained away without any dramas, but as I discovered to my horror, two days of solid, pouring rain just collected in the pump-house area as if it were a very big bucket.
I don’t have any pictures as it was 2am and I was too busy bailing water with a bucket to remember my camera. To give you some idea though, I was wearing gumbies [knee high rubber boots] and the water reached above my ankles.
When bailing was not having an appreciable effect, I tried pulling up the paving stones in the pitch black… Needless to say I eventually gave up and went to bed.
Since that awful night I’ve pulled up the pavers and dug up most of the agi pipe to check if it was working. It was. See exhibit C below:
[Note: agi pipe is agricultural pipe that has holes or slots cut into it. The idea is that water seeps in through the holes and then flows away through the pipe]
So what went wrong? The sand, that’s what. I’d used very fine sand and it basically just clogged up. Water did seep through but very slowly, and so when the flood happened, the water could not drain away fast enough.
Digging all this out has been a back-breaking job, and I still have not been game to test the pumps, but I think they’ll be okay. -fingers crossed behind back- Once I finish, I’m going to hire in someone to install a grate the full length of the agi pipe [in front of the pumps]. Then I’m going to get the rest of the area properly concreted. I shudder to think how much it will cost, but DIY got me into this fix in the first place so I’m not game to learn concreting as a hobby.
Anyone else with DIY horror stories? Please tell so I don’t feel quite so alone [and stupid]. 😦