Highway drain lining drives up safety and puts brake on costs
Drain lining technology from Lanes Group plc is being used to rehabilitate highway drains while helping hard-pressed maintenance budgets stretch further.
Highway chiefs are switching from excavating and replacing defective drains to lining them because the no-dig approach is proving safer and less costly.
Effective maintenance of roadside drainage is a key priority for highway authorities to reduce the risk of flash flooding which can contribute to accidents and traffic disruption.
Working with one highway authority in South West England, Lanes Group’s sewer rehabilitation and lining division has completed schemes to line defective drains at four different locations.
Partnership working, with Lanes teams scoping high-risk sections of roads, allowing the highway authority to make informed choices on maintenance approaches, has been key.
Lanes combined lining with the use of advanced remote access cutting technology to remove tree roots which had infested the drains, preventing the free-flow of water.
Melvyn Newman, the local authority’s site manager for highway maintenance, said: “Lining surface water drains is proving to be a very useful approach to highway maintenance.
“It’s especially helpful where drains are co-located with other services, such as gas and water mains and fibre-optic cabling.
“In these cases, excavation is more complicated to plan and carry out, adding to the costs and the time taken to tackle potentially-serious localised flooding problems.
“Where these issues arise, lining highway drains is proving to be significantly less expensive than excavation and can be carried out in days, rather than several weeks.
“Lining is also less disruptive for road users and safer, because often it needs less traffic management or none at all, and our maintenance teams do not have to work close to busy roads.”
Pipes lined have ranged in diameter from 225mm to 450mm. The longest liner installed so far has been 160 metres.
Simon Bull, Lanes Group’s Sewer Rehabilitation and Lining Manager, said: “We have installed several liners in one village. Conventional excavation would have caused serious disruption for residents over weeks.
“We can rehabilitate the drains to the same standard in a fraction of the time, and local people would barely be aware we are working in their community.”
In one case, 60% of the volume of a 225mm-diameter clay pipe was filled with roots along its length.
These were removed using Lanes’ powerful ProKASRO electric robotic cutter, which can operate up to 110 metres from the entry manhole, allowing the pipe to then be lined.
Two lining techniques were used – hot cure lining and ultraviolet (UV) lining – to take account of differing layouts of each pipe.
Hot cured in place pipe (CIPP) liners are flexible tubes of resin-impregnated needle felt which are inverted into defective pipes using water.
The water, fed into the liner from height, presses the liner tight to the host pipe. The water is then heated to nearly 90 degrees Centigrade to cure, or harden, the resin.
With UV CIPP lining, compressed air is used to inflate the liner and UV light emitted from a UV light train pulled through the pipe is used to cure chemical catalysts in the liner.
Lateral pipe connections are then reopened using the robotic cutter, creating a new pipe within a pipe which has a design life of up to 50 years.
Hot CIPP lining can be used where drains curve and change direction along their run. However, the water used in the process needs to be disposed of at an authorised site because it has a taint from the resin.
UV CIPP lining can be used where there are straight runs between manholes. It uses less equipment, takes less time to complete, and does not create wastewater that needs authorised disposal.