05 February 2019

The Canal IS Level.

by: Bob H.

Well, it may be so on the surface, but like the Duck on a fast-flowing stream, all is far from calm and level underneath. 

Many of us know only too well that there are sections of the Canal which are quite shallow - we on the dredging team (Wet and dry) are working hard to remedy that.  We are removing quite large volumes of silt and other debris to restore the level to around 1.5 metres in the main channel, with deep enough edges to get to the banks. 

One of our problems is that we don’t really know where the really shallow bits are or what volume of silt we have to remove.   Enter a nifty bit of high tech kit.
We found a very helpful company, Land and Satellite Services, 

who have equipment which measures quite accurately the water depth and the precise locations of all the pesky shallow bits. Accurate to 2mm anyway!! 

All the measurements are done without anyone getting in a boat, pontoon or coracle.  It’s all done from the bank with a radio-controlled boat, gps, laptop and a live connection to bang up to date Ordnance Survey data.  Depth is taken every 1/2 metre or so the boat travels. 

Plotted and stored on the laptop, later analysis provides a detailed canal bed contour map and, based on a specified channel section, how much silt we need to remove by dredging.

Did I mention that it’s quick too? 

Today, Mark (LSS), assisted by Bob and Alex (CCT dredging team) did a first pass of the survey from Wallbridge to Ryeford Top Lock.   The little boat covered about 20km and made over 40,000 measurements of depth, on about 3km of canal.

Tomorrow we do a bit of follow-up on sections where trees stop the gps or the mobile signal don’t work because of overhanging trees and mobile dead spots. Thank you all boat crews and dredgers for suspending work tomorrow for a day (silt free water is needed).  We’ll report later on the findings.

"May all your combined leaks never exceed your bilge pump capacity.