Repairs to La Piette Combined Sewer Overflow Outfall begins following storm damage

Work to repair the La Piette combined sewer overflow outfall began on Monday after it was damaged during severe weather over the winter.

Although damage from multiple storms was clearly visible on land, conditions at sea were just as extreme, with powerful currents repeatedly surging over the outfall for hours.

The force of the storms caused significant damage to the structure. Granite stones protecting the pipe were dislodged, steel covers were torn from their hinges, and debris entered the pipe, leading to partial blockages.

A combined sewer overflow is a safety valve within the drainage system that carries both rainwater and wastewater, allowing excess flows to be released during periods of heavy rainfall when the network becomes overwhelmed. Any wastewater is heavily diluted.

Works will be carried out by contractor Geomarine and began on Monday. Teams will remove debris, repair and resecure damaged granite protection, reinstall steel covers and restore the outfall to full working condition.

The work is expected to take several weeks and has been timed to coincide with particularly low tides, allowing engineers maximum access to the structure each 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.”

La Piette Combined Sewer Overflow Outfall is not a continuously discharging outfall and is only used when required to relieve pressure on the network.

Without it, excess flows could back up within the system, increasing the risk of wastewater affecting homes, roads and other infrastructure.

Guernsey Water is also continuing to develop plans for repairs to the Fort George outfall, with further updates to be shared in due course.