No-dig drain lining solves road congestion concern

Drainage and water utility specialist Lanes Group plc has completed a major sewer rehabilitation programme along one of the busiest main roads into Exeter in Devon.

The work involved installation of multiple local structural repairs and one 167-metre full liner in highway drains along the A30 Honiton Road on the eastern outskirts of the city.

Construction and highway maintenance specialist Skanska, working with Devon County Council as its term maintenance contractor, commissioned the Lanes depot in Plymouth to carry out the work.

Pipes with diameters of 150mm, 225mm, and 300mm were rehabilitated in 15 night shifts, with all work completed 10 days ahead of schedule.

A CCTV drainage survey report had originally recommended the replacement of a 167m length of 225mm-diameter pipe, including a section that passed beneath a railway bridge.

Grant Cooper, Manager of the Lanes Plymouth Depot, said: “Skanska was open to alternative solutions and accepted our recommendation that we should re-survey this pipe, just to be sure it needed to be excavated.

“Our survey indicated that we would only have to replace a two-metre length of pipe and the rest could be lined. This prevented the need for extensive excavation work, which was likely to have been made more complicated by the presence of the railway bridge.

“Excavating the pipe would have taken three weeks, causing significant traffic disruption and additional cost. Instead, we could line it in two nights.”

Lanes first desilted the highway drains with high pressure water jetting delivered by a jet vac tanker. The same technique was used to remove extensive tree root infestation.

The short section of pipe was excavated and replaced. Then the whole pipe, including the replaced section, could be lined with one liner, to create smooth snag-free finish.

The 167m ultraviolet (UV) light cured in place pipe (CIPP) liner was installed by a specialist lining team from the Lanes sewer rehabilitation division.

The liner was winched into place and inflated with compressed air. Then a UV light train, a wheeled device fitted with UV lights, was pulled through the pipe.

This cured a UV-reactive resin in the liner, creating a tough, impermeable pipe within a pipe, making the highway drain waterproof and giving it added structural strength.

Drainage engineers from Lanes Plymouth also installed 12 local structural repairs, also known as patch liners. These are 1m-long liners for repairing small and isolated defects that are cured in ambient temperature.

Both techniques are ideal for repairing highway drains because they are carried out faster, often with minimal or no traffic management, and at less cost than conventional excavation.

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