Saturday, July 15, 2017

How I revamped part of the stream

Since 2012 (see Progress Report 41), I have been planning to add a watermill beside the stream on the approach to Peckforton Station. It's no coincidence that my two favourite narrow gauge railways (the Southwold and the Welshpool & Llanfair) followed rivers and both passed watermills. I have already created a siding to serve the mill (see also How I constructed the mill siding) and bridged the stream to connect it to the main line (see How I constructed a small wooden trestle).

Getting around to constructing the mill is one of those jobs I have been putting off as I felt the stream needed to be modified to include some sort of mill stream and this would require some major civil engineering work. However, during the Spring a couple of years ago, I was fascinated to watch a mouse gathering nesting material and disappearing under the trackbed beside the stream.

Despite my interest in wildlife, I was not keen on having such fauna nesting so close to my back door and so took some deterrent measures to discourage it. Then recently, I discovered another mousehole beside the track close to the original and, at the same time, found that the stream seemed to be losing water.
 I put two and two together and figured the mice must have chewed into the plastic liner underneath the stream over which concrete had been laid (see How I constructed the stream).

My only recourse, I felt, was to break up the concrete to expose the liner and replace it. This would also entail redoing the trackbed which runs alongside the stream.

The track was taken up by removing the screws which held it to the concrete 'breeze' block trackbed (see How I laid my track) .......


...... and the ivy was removed from the retaining wall.

The concrete blocks were dug up (you can see the plastic liner on the edge of the stream on the left).

Meanwhile, one of my resident blackbirds decided to monitor proceedings and help himself to a few grubs and worms which had been exposed by my excavations.

The concrete and rocks lining the stream were then attacked with a hammer and crowbar ........

 ...... to expose the plastic liner beneath (the mill siding is in the background).

After clearing the debris, I inspected the lining. Lo and behold, there was no damage in evidence!! To double check, I ran the pump to see if any leaks became more apparent - but none appeared!

It seemed all my efforts were in vain - the leak must be elsewhere!

It was at this point, that it occurred to me that the culprit might actually be the cover for the sump. The sump is a plastic dustbin with it's lid inverted, perforated and placed on top to act as a permeable cover (see How I constructed the stream).

Of course, if the holes in the cover were blocked with leaves and soil, then the water would not be able to drain back into the sump.

I removed the lid and cleaned out the sump (much to the consternation of the frogs which populate the area) and ran the stream again. Rather than needing to be topped-up after fifteen minutes as was happening previously, the stream now ran happily for two hours and even then needed only half a bucket-full to top it back up to the original level.

I try to be sanguine about such issues and so looked for the silver lining to the outcome of my labours. I had an ideal opportunity to remodel this part of the stream and provide the mill stream, I decided.

The blocks for the trackbed were re-installed (making sure they were well bedded-in); my blackbird returning to supervise proceedings.

Once all the blocks had been re-installed and levelled ......

 ...... concrete was forced into the spaces between them (I use rubber-gloved fingers for this job - much easier to get the concrete where it's needed and extremely satisfying).
 

Various chunks of sandstone were then positioned along the edges the stream, with a few in the stream bed on top of the liner, and cement forced in and around them (the concrete on the stream bed is about two inches deep). This was left to set.

The following day, a wire brush was used to remove 'green' concrete from the faces of some of the rocks and the concrete was then left for three further days to ensure it had fully set .

The track was re-instated - being fixed to the concrete blocks with Rawlplugs and screws.

The pump for the stream was then energised to check the newly installed weir and mill stream behaved as they should.

The mill-stream can be seen on the right in the middle distance. This will be built-up eventually with stonework and a set of sluice-gates will be added to restrict the flow to the wheel. I would like to simulate the ponderous turning of a real life waterwheel if that is achievable.

Looking from the opposite direction, the mill building will be installed on the plateau on the left, below the mill siding.

To check everything was functioning as it should, the cover was re-instated over the sump and the pebbles were given a thorough clean before being placed on top.

I was pleased to find that there was still minimal loss of water from the stream and so, while the civil engineering had been unnecessary to stem the leak, the modifications were now in place for the installation of the mill building (see How I constructed a water mill - pending).

Once the weather improved, the track was ballasted using my tried and tested cement and PVA method (see How I ballast my track) .......



...... and then tested.


I am pleased with the outcome. The trackbed beside the stream was in need of refurbishment as it had dropped slightly (possibly due to the rodents' excavations) and I had wanted to remodel the stream to accommodate the water mill. In addition, the ivy (which was self-propagated) had become somewhat overwhelming on this stretch and needed to be 'tamed'. And so, several objectives had been achieved - and the source of water-leakage had been explained and remedied.

It's very reassuring to know that, even after ten years of use, my technique for stream construction still holds water, so to speak -

The next job is to make the mill building and to experiment with making the sluice gates to control the flow of water to the wheel. I now have plenty of excuses to indulge in a bit more water- and concrete-play which is, of course, very important for my intellectual development.

I have already started researching the design of the mills which abounded on the River Gowy in the immediate area and realised their design had much in common ....






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