An emergency safety valve on a Guernsey sewage pipe must be repaired before winter storms return to the island, after it was damaged during previous storms.
Guernsey Water said it started repairing the sewer overflow outfall at La Piette on Monday, which was damaged by “extreme sea conditions and powerful currents”.
The stormy conditions dislodged some granite protection stones, while steel covers were torn from their hinges.
Guernsey Water said this allowed debris to enter the pipe, which has caused partial blockages.
Operations Manager Jon Holt said the pipe played “an important role in protecting the wastewater network, particularly during periods of heavy rainfall when the system is under pressure”.
The pipe carries a mixture of rainwater and heavily diluted wastewater, and it operates only during intense rainfall when the network leading to the Belle Grève wastewater centre is overwhelmed.
The utility company said that without this overflow system, excess flows could back up, risking flooding to homes, roads and other infrastructure.
The utility company also expects overflow events like these to become more common, due to climate change.
Engineering contractor Geomarine has been hired to undertake the repairs, which included clearing internal debris, relaying and regrouting the granite stones, and installing new steel covers.
Mr Holt said: “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.”
He confirmed that operations would be carried out in phases over the coming weeks, with the work timed to coincide with low tides to “make best use of tidal conditions” and allow the engineers maximum access each day.
Fort George update
Guernsey Water has also provided an update to another damaged outfall.
A spokesperson said it is currently developing a repair plan for the Fort George outfall, and has met with harbour divers and intends to confirm a date for preliminary repairs in due course.
That pipe was also damaged earlier this year, with officials warning it was “unlikely to be a quick repair”.
Despite the damage, water quality tests from Soldiers Bay, where the outfall pipe is located, revealed “positive” results.