Lanes jetting technology helps cut costs in weir repair
Lanes Group engineers have cleared a blocked river culvert as part of an initiative to save tens of thousands of pounds while a weir is rebuilt.
The Environment Agency has commissioned work to carry out major repairs to the weir on the River Medway, close to Royal Tunbridge Wells, in Kent.
Main contractor Jackson Civil Engineering wanted to use a bypass culvert built into the wall of the weir. The alternative was to over-pump the water through temporary pipes, a process that would have cost an estimated £80,000.
The problem was that the culvert, 12 metres long and 750mm in diameter, had become blocked by silt, debris and tree roots.
So Jackson commissioned Lanes Group, the UK’s largest independent supplier of wastewater, utility and underground pipeline rehabilitation services, to clear the debris and clean the culvert.
Barry Glew, project manager for Jackson, said: “The Lanes team did a very good job. Access was not easy, and they responded well to some changes in procedures needed to allow the work to go ahead. They have contributed to the most cost-effective plan for completing these important works.”
Lanes engineers based at Sevenoaks, Kent, used a JHL jet vac tanker to clear the culvert. John Gilbert, south east area development manager for Lanes, said: “The pipe had significant tree-root intrusion.
“However, by using a specialist root cutting jetting head and operating at full power, we were able to cut through the roots and wash out the silt and debris, both of which were then collected by the jet vac’s suction pipe.”
A camera survey, also carried out by the Lanes, confirmed that the jetting had worked well. The culvert was clean, and clear.
Significant enabling work was needed to allow the culvert cleaning operation to go ahead.
Jackson engineers first installed sheet piling in the Medway around the weir and the culvert inlet to block the water. Then, large bags filled with shingle were placed across the stream, Botany Stream, below the culvert outfall.
This allowed water to be over-pumped from the Medway into Botany Stream to keep it flowing, but prevented the water backing up towards the weir and the culvert.
Once the culvert was clear, and other exploratory work by Jackson engineers completed, a stop log in the sheet piling was pulled, allowing water to flow back over the weir, and through the culvert for the first time in a number of years.
Barry Glew, project manager for Jackson, said: “The plan now is to put a twin-wall pipe through the culvert, so it can take the full flow of the diverted water while the weir is rebuilt, preventing the need for costly over-pumping.”