Repairs begin to storm-damaged La Piette sewer overflow outfall
- Repairs have begun on the La Piette combined sewer overflow outfall after it was damaged by severe winter storms
- Granite stones were dislodged, steel covers torn off, and debris caused partial blockages in the pipe
- Contractor Geomarine will remove debris, repair granite protection and reinstall steel covers over several weeks
- Work has been timed to coincide with low tides to give engineers maximum access to the structure
- The outfall acts as a safety valve during heavy rainfall to prevent wastewater backing up into homes and roads
Work has begun on repairing the La Piette combined sewer overflow outfall after it sustained significant damage during severe winter storms.
Contractor Geomarine commenced repairs on Monday to restore the infrastructure, which plays a critical role in Guernsey's drainage system during periods of heavy rainfall.
The outfall suffered extensive damage from multiple storms over the winter months. While the destruction was visible on land, conditions at sea proved equally extreme, with powerful currents repeatedly surging over the structure for hours at a time.
The force of the storms dislodged granite stones that protect the pipe, tore steel covers from their hinges, and allowed debris to enter the system, causing partial blockages.
A combined sewer overflow functions as a safety valve within drainage networks that carry both rainwater and wastewater. It allows excess flows to be released during heavy rainfall when the system becomes overwhelmed, with any wastewater being heavily diluted before discharge.
Repair teams will remove accumulated debris, repair and resecure the damaged granite protection, reinstall steel covers, and restore the outfall to full working condition.
The project is expected to take several weeks. Works have been scheduled to coincide with particularly low tides, providing engineers with maximum access to the structure during each working day.
Guernsey Water Operations Manager Jon Holt said: "The La Piette outfall plays an important role in protecting the wastewater network, particularly during periods of heavy rainfall when the system is under pressure.
"The recent storms caused damage and resulted in the outfall potentially being unable to operate as intended, so it's important that we carry out these repairs now in the summer months before the winter storms return."
"We have planned the work carefully to make best use of tidal conditions, so we can carry out the repairs safely and efficiently," he added.
The La Piette combined sewer overflow outfall does not discharge continuously and is only activated when required to relieve pressure on the network during exceptional rainfall events.
Without a functioning overflow system, excess flows could back up within the drainage network, increasing the risk of wastewater affecting homes, roads and other infrastructure across the island.
Guernsey Water confirmed it is also continuing to develop plans for repairs to the Fort George outfall, with further updates to be shared in due course.
Guernsey Water oversees the collection, storage, treatment and distribution of drinking water to over 25,000 homes and businesses across the island, as well as the collection and safe disposal of all wastewater.
The company currently manages more than 100 facilities, including pumping stations, water treatment works, sea outfalls, land and office buildings.
Q&A
Q: What is a combined sewer overflow?
A: A combined sewer overflow is a safety valve within drainage systems that carry both rainwater and wastewater. It allows excess flows to be released during heavy rainfall when the network becomes overwhelmed, with any wastewater being heavily diluted before discharge.
Q: How long will the repairs take?
A: The repairs are expected to take several weeks. The work has been scheduled to coincide with particularly low tides to give engineers maximum access to the structure each day.
Q: What damage did the winter storms cause to the outfall?
A: The storms dislodged granite stones that protect the pipe, tore steel covers from their hinges, and allowed debris to enter the system, causing partial blockages. Powerful currents repeatedly surged over the structure for hours during the severe weather.
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