I peaked early when I posted my power saw shedlet 6 days before this contest was announced so I will show you my raised pond instead :)
The project began after watching wheelchair users struggle to dip nets into a pond with a long drop to the water, I suggested building one that brought the water up to them would be a nice thing to do.
Step 1: The Site
I was offered a piece of ground to work on, not many photo's of it as I spent most of my time trying to stop my wellington boots being sucked off my feet. It was a quagmire and all ruts and bumps but you work with what you have got right?
I measured the area up and put some pegs into the ground to give me an idea of size....
Step 2: The Design
I based the design on using 2.4m long x 200mm x 100mm oak sleepers.
You will see that the back of the pond runs into the hillside the front changes direction at every join in the woodwork, this is to ensure that it can safely support the 55 tons of water that it will contain.
I spent a lot of time designing the wheelchair knee holes, making a scale model to make sure it looked right.
Step 3: Preparing the Ground
I did not relish the idea of working in the mud so the first thing to do was to make a stable, dry, flat area to work on. The first thing to go down was hardcore, laboriously wheelbarrowed in by helpful volunteers:)
The hardcore was then covered with course sand, rolled flat, followed by a layer of geotextile.
The wheelchair friendliness comes from these things half meter square plastic waffles that, once laid were filled with 10mm shingle.
Step 4: The Wall
I sent my cutting list to the local sawmill and a few days later the truck carrying it arrived groaning under the weight of the timber! It was unloaded using the trucks Hiab crane thank goodness
This wood is green and very heavy and I had a lot of help from a mate moving it around, we used lifting tongs to carry and place the pieces.
The bottom layer was nailed into the ground using 250mm long pins recessed around 50mm into the wood, it was leveled using my low cost laser level which made life so easy! Further layers were pinned through with the nails and screwed to the one below, the process continued until the wall was up to full height with just the capping rail to be fitted.
Step 5: Preparing for the Liner
The butyl rubber liner was ordered at the same time as I ordered the timber as it had a 2 week lead time. Whilst I waited for it to arrive I ran a wooden rail along the bank at the back of the pond and constructed a soil ramp to allow any animal that falls in a way to get out again, this was all covered with geotextile and the bottom of the pond was covered in carpet that my mate managed to find dumpster diving :)
A layer of thick underfelt was then stapled all around the woodwork and laid into the pond.
Step 6: The Liner Goes In
With the help of around a dozen willing volunteers the rubber liner was heaved and pulled into place and stapled to the top of the wall and buried along the bank at the back. Most of the top rails were attached at this point and as it was raining the pond started to fill!
Step 7: Finishing Touches
At the kneehole stations the rubber liner is in danger of damage so I made a set of protectors out of aluminium sheet that was installed under the top rail.
There was also a need for an outlet to ensure that the pond would not overflow in the wrong place, I constructed an aluminium sheet spillway that sends the water into an existing soakaway and land drain, it has 2 parts that create a labyrinth join which was sealed with Butyl mastic.
Step 8: Let It Rain!
I have been monitoring the water level since the build finished at time of writing it still has around 150mm to go.
I have also been checking what is living in the pond already, nearly a dozen species have arrived including mayfly and damselfly.
I also noticed that Acylius beetle larvae were struggling to climb the rubber to get out to pupate, for the short term I constructed a soil filled ramp which a number of them have used. I decided to instal some astroturf on the back edge to cover the exposed liner, this will help critters get in and out of the pond. it looks very unnatural and new at present but it will gradually get soil and dead leaves stuck to it and it will merge in with the surroundings.
Step 9: What It Is All About!
The pond had only been finished 6 weeks before and my first wheelchair users came along for a dip. It was sowing it down with rain but that didn't dampen spirits and they found lots of interesting critters!
They gave me lots of useful feedback on using the pond dipping equipment, for instance a shelf to park the white collection tray so that I can make it an even better experience for future users.
Next job is a floating island to get some pond weed started.