'Bottleneck' creates £58k sewage problem

South West Water has pleaded guilty to two offences of discharging sewage effluent from its Camels Head sewage treatment works at Plymouth into a tributary of the Tamar Estuary

The consent to discharge for the South West Water site states that sewage can only be discharged from the storm weir – a physical barrier that can be set at different height levels – when flows exceed 420 litres per second.

However, investigations after numerous sewage spills in 2011 revealed that the weir at Camels Head had been set at 340 litres a second. This meant the weir operated more often than it should have and that untreated sewage was discharged.

South West Water said a pipework restriction further along the treatment process acted like a “bottleneck”, preventing the site coping with a higher flow than 340 litres a second.

The company claimed that the treatment works would have flooded if sewage had not been allowed to discharge from the storm weir. Plymouth magistrates’ court fined the company £50,000 and ordered it to pay £8,375 costs.