We came up with the slightly crazy idea of putting a lid on it and using the space underneath as rainwater storage. I sketched up some ideas, we approached an engineer and before long we had a workable design.
Cleaning was lot of work. There was about a foot of accumulated sludge in the bottom.
After many hours of pressure cleaning it was starting to look better. It’s a huge pool, about 10m long and 2.2m at the deep end. We thought about sealing it with a paint on sealer at this point, but we can always do this later if leaks are a problem.
The solution we used for the lid is called “Speedfloor”. It uses steel joists spaced ~1m apart to suspend a concrete slab. It’s commonly used in multi-story carparks in Australia.
You can also see the submersible pump feeding into the pool from what was originally the overflow point. The pump provides mains pressure and is plumbed to the house (via 2 filters).
I have two of these 500L tanks catching water from both sides of the house. Both downpipes have first flush systems and the tanks act as settling tanks to improve the water quality in the main tank. They both gravity feed into the pool via underground pipes.
Back to work assembling the raised garden beds. We fit 9 total, each about 2.2m long and 1.2m wide. They each have a liner to stop soil washing out and gravel base to aid drainage and keep water off the slab as best we can (even though it shouldn’t matter with the grade of concrete used).
We tried out wicking beds made from IBCs but were concerned about the extra weight the water reservoir would add.
We’ve grown almost everything you can think of – permanent beds grow raspberries, strawberries, blueberries, rhubarb and asparagus. Other things we’ve tried include tomatoes, pumpkins, zucchini, squash, turnips, beetroot, broad beans, string beans, snow peas, various chilies, artichokes, spring onions, garlic, capsicum, kale, lettuce, spinach, loads of herbs etc etc etc!