Sealing leaks in a canal side embankment
Oxford Hydrotechnics use advanced resin injection techniques to control leaks through a canal wall and into public gardens below.
Oxford Hydrotechnics were approached by the client, Kier MG, as part of an ongoing commitment to the Canal and River Trust’s canal maintenance framework. H2OX were asked to propose a solution to leaking canal water through a canal wall, beneath the adjoining towpath embankment.
Defects in the canal wall had resulted in long term leakage issues. These issues were particularly noticeable in a public garden, located around 4.5 metres below the canal, where water was seen visibly flowing at a significant rate. The flow of canal water through the tow path, down into the garden, had resulted in the garden being unusable for a number of years.
The video below shows conditions prior to works being carried out by Oxford Hydrotechnics.
Upon inspection, Oxford Hydrotechnics’ highly experienced engineers were able to quickly locate a number of the flowpaths by identifying probable causes and symptoms of water leakage, accelerating the repairs process. A tree root was seen protruding from the side of the canal in one area, which would likely have created a pathway through which water could flow. An additional location was noted further along the towpath, where an area of sunken ground, originally believed to be a naturally formed rainwater puddle, indicated potential soil washout beneath. These locations were confirmed using Oxford Hydrotechnics’ dye testing method, where an environmentally safe dye is injected at intervals along the canal wall. The dye is then carried with the water, identifying flowpath locations to H2OX engineers.
H2OX’s innovative proposal was to inject a hydrophobic, polyurethane resin, into the flowpaths within the canal wall. The resin would react with the water, present in the flowpaths, before curing to form a closed cell, lightweight foam. This lightweight foam would then create a seal, thus closing off the leaks.
As the canal wall was a heritage structure, Oxford Hydrotechnics’ engineers proposed a method whereby injection lances were installed into drill holes, specifically drilled through the mortar between the canal-side coping stones. This technique ensured that damage to the canal side during the repairs was minimised. Resin was then injected through the lances to the leak locations using the least amount of pressure possible, further protecting the masonry.
In total, Oxford Hydrotechnics treated 80 linear metres of the canal side, at depths ranging from 1.5 metres to 2 metres deep, corresponding with the natural undulations of the towpath.
The heavy flow of canal water into the below gardens and surrounding areas was successfully treated. The previously unusable garden areas were re-turfed and returned to a usable condition. On a revisit, a number of weeks later, the area of wall which sustained the heaviest flow of water on first inspection, was found to be completely dry and no further leakage was noted.
All works were completed within 12 shifts, minimising disruption to canal users and homeowners in the vicinity.