To the general relief of all concerned, site work recommenced at the Vernal Equinox, otherwise known as the first day of Spring. Believe it or not this is the fifth time the society has had to restart work on Pryces to Crickheath after an enforced break. The others were due to newt exclusion and trapping (three times) and last year’s virus lockdown. Good progress was made on bank construction, channel bed treatment, and the newt fences benefitted from a spring clean.
On arrival on site, in appropriately Spring-like weather, it was a case of water, water everywhere. Some of it had managed to find its way into the welfare cabin via a number of leaking pipes, but some efficient repairs soon fixed that. A couple of weeks of dry weather had done little to lower the level of the local groundwater, a large proportion of which seemed to have found its way into the channel. The channel pumping actually started on Wednesday and although this significantly reduced the level, three pumps were needed for the duration. Such was the depth of water at the LAF end of the site that the channel bed was not visible until Sunday afternoon.
The major construction task was the start of work on the third of the four lengths of bank, sited over peat areas, which require surcharge. The one in question is on the towpath side at the Crickheath end of the site. This area has already seen some construction activity with the installation of the culvert. The first task was to stem the flow of water between the channel and the adjoining ditch via the culvert excavation. A temporary dam of repurposed newt fence stopped the flow and the area around the culvert was then plugged using large quantities of puddle clay. This was a difficult task which occupied ten volunteers for most of the day. The banks were then stripped of vegetation and both inside and outside faces benched. The final task late on Saturday was installation of the settlement measurement points on the original ground on the top of the bank.
On Sunday the machine work gang transferred to the other end of the site where the final ‘surcharged bank’ is to be built. Here a 25 metre length of channel bed was excavated to grade and treated with cement grout. When this work started on Sunday morning the water level in the section through which the dumpers had to travel was still quite high and there was a debate as to whether the drivers required a dumper licence or a mariner‘s certificate. It is good to report that, apart from a little sea-sickness, they all survived the experience.
The other major job was the annual overhaul of the newt fences. It took two days to repair the various bits of damage and to return them to pristine condition.
The monitoring of subsidence of the two banks at the oak tree has been going on for over three months now, and it might be interesting for readers to see some of the results. The graph shows the amount of settlement for the towpath bank which was finished last year. The points exhibiting the most subsidence are at mid-point in the length and correspond to the deepest dip in the original towpath. For context 140mm represents about a third of the distance between the finished towpath level and the design finished water level. Better to get the subsidence now rather than when the canal is open to boats!