I made use of your helpful project section while planning this build, so thought it might be useful for others to have these pics and details of my project...
The pond build used your G1/2 Jarrah/Tropical hardwood railway sleepers, I found the various lengths you supplied useful to minimise the amount of cuts I would have to make. I designed the sides to be 210 +120 + 1 sleeper width. It would have been even easier if I'd had the room to make it 210 + 1 sleeper width wide, but I had to cut the end railway sleepers to fit in the space available.
Jet washing the railway sleepers was very messy, but worthwhile as they were a lot nicer to handle afterwards, looked good as soon as the build was finished and i didn't end up with all the water/debris inside the pond hole. I'd ordered enough railway sleepers to make the pond and edging for two raised beds. Two of the longer railway sleepers were very rough and 'gnarly' and I set these aside for the raised beds. I saved the 'best looking' sleepers for the cap layer, one had a particularly nice witness mark in it from a track chair and this was used for the end piece next to the house. I used a rachet strap to secure two railway sleepers at a a time onto a car wheel dolly to transport the railway sleepers from the drive to the garden, which worked well.
The pond was replacing a hot tub around which I had built decking that I didn't want to get rid of or move. This presented a bit of a challenge as the decking was sat on an old slabbed patio that one end of the pond would be seated on, so this end had to be pre-assembled then bedded onto mortar on the slabs, whereas the far end was bedded on concrete footings, dug into the sloping garden. I was able to cut the railway sleepers with a circular saw by making cuts from both sides meeting in the middle, sometimes a small section was left in the centre and needed to be hand sawn, but this wasn't too difficult (but having cut through ~5mm a couple of times I certainly wouldn't want to try 210!)
The timberlock screws were absolutely great and the long drill bit supplied by you (a Makita one) was also perfect for the job, as long as I drilled 1/2" or so then pulled the bit out to clear the flutes (failure to do this would cause excess heat build up, especially when drilling deep holes as all mine were). I bought a nice fluted bit for the countersinking, but found it would stall the drill as the screw tip pulled it into the wood too fast, so swapped onto a flat wood bit that worked better. I did need to make some cut outs in some of the railway sleepers for pipe access, an overflow point and to get the cap sleepers to sit flat(ish). To do this I made boundary and parallel cuts with a circular saw and chiseled out between them - this was quite easy as it used the wood's hardness 'against it'. My power plane would take off about 1.2mm at a time without stalling, but I only used this to shave off a couple of small areas.
The railway sleepers were rough and uneven, so I lined the inner walls with 9mm OSB, which was flexible enough to curve where there were protruding ends etc, to give a nice smooth surface for the underlay/liner .
The finished pond looks great, the 'character' of the railway sleepers is exactly what we wanted :)
RAILWAY SLEEPERS USED:
Reclaimed Grade 1-2 untreated tropical hardwood railway sleepers
Thank you so much for the photos and practical account of your brilliant railway sleeper pond construction. It is really inspiring and practically useful for anyone wanting to follow in your footsteps. You describe perfectly both the challenges and solutions of using uneven reclaimed railway sleepers, and how you approached each stage in the building process. Your satisfaction and pleasure in the finished pond is there for all to see.