August 2020 work party report

This month saw a double helping of work party action as the society attempted to make up a little of the time lost due to newts/ground investigations/the virus.  Both events were highly productive and as a result the appearance of the site has changed radically. 

Crickheath South

The first work party continued where we left off in July, with dry and sunny weather assisting both vegetation clearance and earthmoving. The vegetation gang once again excelled themselves.  On the Friday, in temperatures of over 30 degrees, they cleared the steep ditch-side slope of two long lengths of towpath embankment in preparation for the diversion of the newt fences in those locations. This was necessary to permit the eventual partial demolition of the towpath in those areas.  On the next day they moved into Crickheath South – the area on the Pant side of Crickheath Bridge – to clear some 60m of channel so as to permit ecological, topographic and structural condition surveys to take place.

Earthworks featured in all six working days in the month. The main job was the treatment of the channel bed. In the first work party much of the effort was directed at removal of silt from the channel between the Oak Tree and LAF and treating the channel bed with cement grout to a depth of 200mm. This technique effectively turns the surface into a block of concrete. After allowing the cement to cure the areas are covered with layers of terram and geogrid topped off with up to 300mm of crushed stone.  Although some localised soft spots remained the resulting construction was able to support the weight of the 8 tonne digger and loaded dumpers.  As work moved closer to the Hell Hole, the extant ground conditions deteriorated with large amounts of peat in evidence. Here it was necessary to excavate down a bucket depth and gradually return the material mixing in large amounts of cement grout in the process.  Even after all of this effort vibrations from the machines can be felt in the ground several metres away.  However we console ourselves that if the channel bed can support the weight of a large moving machine it will have little trouble with its eventual static loading of canal water.  

2A bed formation
2A bed formation
2b land drain

The second work party saw some rain but not enough to interfere with earthworks activity or with the training of two new dumper drivers to add to the rota.  The most extraordinary performance of this work party was that of the gang installing the land drain.  They finished 85m in the weekend through just about the entire range of bad ground conditions that this site is notorious for.  Some going!  Elsewhere concrete pads were installed on the banks in the subsidence area near the Oak Tree.  These are part of devices to measure the amount of subsidence during construction of the permanent banks. The soil used in this construction has to have specified moisture content and the on-site method of testing this was successfully trialled.  A long bout of setting-out completed the weekend.

Three work parties in from restart it is possible to get a glimpse of the new normal. On-site mechanisation is much in evidence – six machines at the last work party – so the operation is beginning to resemble more a commercial contractor than that of a traditional volunteer group.   The revised working and welfare methods featuring masks, social distancing and sanitising have quickly become accepted but the off-site socialising is greatly missed.   Alas as things stand these arrangements are likely to continue for the foreseeable future.

Posted in Montgomery Canal, Pryces Bridge to Crickheath Bridge Restoration, Restoration, Work Party.

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