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Montgomery Canal Restoration Work Party Report - October 2015

October 02 - 04

That was the work party that was! The Society took full advantage of the good conditions created by the Indian Summer. Substantial progress was made on shaping the channel, preventing water entering the works, and establishing a means of getting water out of the works. By the end of the weekend the appearance of the site was utterly transformed.

The work on a work party Friday is usually a low-key collection of things such as deliveries, pumping, and ecological searches - all necessary preparation for the operations on subsequent days. The ‘preparation’ this time, which consisted of all of the above, barely lasted until lunchtime, whereupon work started on more substantial tasks. The first was the continuation of work which had started during the last work party to seal the stop planks with puddle clay. This had resulted in a reduction of water ingress via the planks, and a number of volunteers spent Friday afternoon finishing that job. The other task was the start of earth-moving in the channel. The 8-tonne excavator got to work reducing the base to 150 mm above grade and shifting the resulting spoil onto the sloping towpath bank. The material will remain on the slope for the winter to allow it to consolidate before final shaping next year. This work continued for the next two days at the end of which about 50 metres of channel was profiled.

Much of the work on Saturday revolved around the remains of the pile of puddle clay near Pryces Bridge. Much of this had been used to construct the dam which forms the south end of the site but the residue has become a favourite haunt of newts. For this reason the clay had to be removed before the newt hibernation season to allow work to continue in the area. The clay was broken down using the small excavator and hand searched before being transported to one of three locations. Some went to storage in the new extension to the compound and a small quantity was used as fill. The majority of the clay, however, was placed at the back of the Pryces Bridge stop planks and puddled in. The sight of the volunteers moving the clay by wheelbarrow and turning it to puddle using buckets of water, rammers and boots was one which would have gladdened the hearts of the ‘navigators’ of two centuries ago! The finishing touches to the dam were made by the small excavator which, although not having quite the historical resonance of navvies’ boots, produced a very neat job. Would the dam hold water though?

The other major Saturday task was the construction of a ‘gravel chute’, a means to deliver the pea gravel required for the construction of a french drain. This impressive looking device is a development of the block chute which the Society has used for a number of years. Both enable heavy materials to be delivered to the bottom of the channel without tracking dumpers along the bed thus avoiding damage to the channel surface. The gravel is delivered via a 6 meter long, 225 mm diameter drain pipe, widened at the top end, which sits on top of the block chute. The gravel, delivered in bulk to the aggregate bins in the compound, is loaded into buckets of manageable weight and transported along the top of the offside bank to the chute. Here it is tipped into the pipe which directly delivers it to the drain trench. At least that was the plan - but would the chute work in practice?

The answer to the first of Saturday’s questions was evident during the pre-work site inspection on Sunday. The clay dam appeared to have blocked most of the leaks, not only from the stop planks but also from the wing walls of Pryces Bridge. The amount of pumping required before work could start on Sunday was minimal. The answer to the second question had to wait a few more hours until the completion of the first section of trench in the bed of the channel adjacent to Pryces Bridge. Although several hundred metres of similar drain had been installed on the Redwith-Pryces section there were a number of differences on the current section – notably larger pipe and prefabricated sumps – which required a slightly different construction method. In the event the excavation of the trench for both sump and pipes, through good ground, was straightforward, and the pipes were installed without fuss. The gravel chute worked perfectly (who doubted it?) and by the end of Sunday 12 metres of drain was finished.

At long last the restoration is beginning to pick up some momentum. Despite the vicissitudes of the year, real progress is now being made.

 

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Puddling the stop planks
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The gravel chute in action, or 'how many people does it take to empty a dumper into a hole?'
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Installing the sump at the start (or end?) of the drain
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Surveyors in deep discussion
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