Collapsed sewer caused Swansea beach pollution

Richard Youle, local democracy reporter

A collapsed sewer near the River Tawe was the cause of a discharge which prompted the authorities to warn people not to swim at Swansea beach.

The blockage caused sewage to enter a surface water drain, and from there it entered the river and then the bay.

The update was given by Hamish Osborn, of Natural Resources Wales (NRW), at a council scrutiny meeting.

Mr Osborn said Welsh Water had traced the discharge and that the problem had been rectified, although he didn’t say where it was.

NRW initially didn’t think the discharge levels would have been significant enough to impact on the beach water quality, said Mr Osborn, but after some investigations were carried out it decided “a precautionary approach” was required.

Swansea beach is one of eight designated beaches in the county where bathing water is sampled and tested between May and September. Swansea beach is the only one with a “good” rating; the others are “excellent”.

Water quality

Tom Price, from the council’s pollution control department, told the environment scrutiny panel that data such as bacteria levels from tributaries of the Tawe enabled the council to provide hourly updates on Swansea beach’s water quality.

He said a robot in effect typed the updates onto an electronic display board on the beach, near the Slip Bridge abutments.

NRW carries out testing on designated beaches, while the council has historically tested water at un-designated Broughton Bay, Gower, and also at the Rhossili end of Rhossili Bay. Mr Price said these two sites met the “good” criteria for the last two years.

On the subject of discharges, Mr Osborn said some sewerage systems also accepted surface water after heavy rainfall to prevent blockages backing up into people’s homes, while others didn’t.

Mr Osborn said water companies had to follow many rules when they were given discharge permits by NRW.

He said a recent alert for Caswell Bay was likely to have been a discharge from the Bishopston treatment works, which discharges at Brandy Cove.

He said another alert for Langland was related to an emergency overflow system there, which he said NRW had “certain issues with” and was talking to Welsh Water about.

Mr Osborn said he didn’t think these spillages had resulted in a substantive effect on water quality. He also said Swansea Bay’s water quality had, over the years, improved considerably.

The meeting also heard that at high tide, salt water at the mouth of the Tawe overtopped the barrage, but the dissipation process was accelerated by a series of underwater aeration units as far back as the Liberty Stadium area which shot fine bubbles of air into the river.

Overflows

Cllr Christine Richards said she was concerned about data she had seen about the sewerage systems which accepted storm water run-off, known as combined sewer overflows.

She said one of them, in Clydach, had discharged into the Tawe 154 times in 2020 for a period of 1,166 hours.

Cllr Richards also suggested that the official May to September bathing season might need looking at, considering how many people swam all-year round.

Mr Osborn said the discharge data cited by Cllr Richards was “sobering”, and that some combined sewer overflows upstream in the Tawe were causing some concern.

“We’ve been discussing with Welsh Water for many years about the Trebanos sewage treatment works,” he said.

Mr Osborn said NRW was well aware of the issues, but added that phosphorus levels in the river – a signifier of damage to aquatic wildlife – were “reasonable”.

He added that climate change would “unleash” problems on the water environment, such as higher volumes of run-off during intense rainfall and also periods of low river levels, which adversely affected migrating fish like salmon.