Lanes waits for time and tide to clear sea outfall pipe

Lanes Group drainage engineers have cleared a 160 metre sea outfall pipe by working in windows of opportunity created by rapidly changing sea levels.

They teamed up with marine engineers to successfully complete the unusual project at Penarth in Vale of Glamorgan, South Wales.

The Lanes team finished the work in just seven days, but had to start their shifts as early as 5am and as late as 5pm each day, to accommodate the changing tides.

Lanes’ Cardiff depot was appointed by marine and civil engineering firm Kaymac to support a project to clear the pipe, which had seen a build of silt and brick along its length.

Kaymac had been commissioned to manage the work by Morgan Sindall, on behalf of Dŵr Cymru Welsh Water.

Damian Tranter, Area Development Manager for Lanes Cardiff, said: “This was very much a case of working when the sea allowed us to.

“Water levels change rapidly along that stretch of coast, and health and safety was of paramount concern. On some days we had as little as a three hour window to work in before we had to clear the area.”

The build-up had been caused by the deterioration of an existing section of brick egg outfall, which resulted in bricks being washed into the pipe.

The first step was to remove around 20 tonnes of silt which had built up behind the bricks.

This was achieved with a Lanes recycler jet vac operating from on the beach, where sand was firmest, using a 60m long jet vac hose to reach an outfall pipe manhole.

A joint Lanes and Kaymac team then worked from the sea end of the outfall to remove bricks and rubble that filled a 90m section of the pipe.

Damian Tranter said: “A temporary sump was dug into the beach and a high volume drainer pump was used to keep it clear. The sump was used to contain bricks cleared from the pipe using a remote jetting reel, with a 200 metre hose.

“The bricks were then cleared out by Kaymac personnel using an excavator and removed from the beach with a tracked dumper. With, at all times, a close watch being kept on the tide.”

Finally, a CCTV drainage survey confirmed that the pipe was 100% clear, and in good condition.

Despite the difficulties faced by team, the work was completed a day ahead of schedule, leaving the outfalls and associated asset fully operational.