South West Water has been ordered to pay £33,515 in fines and costs following a major sewage spill from one of its largest treatment works.
The case was brought by the Environment Agency.
On August 26, 2010 the company reported pump failures at its Plymouth Central sewage treatment works. Normally four pumps are used to lift sewage up a deep shaft and into the works for treatment, but three of these failed leaving just one operational pump.
There was heavy rain prior to the spill and sewage started to be discharged into the Plym estuary. This discharge should have stopped after the rain, but the loss of the main pumps resulted in sewage being discharged via the site’s storm overflow system for three days longer than was permitted.
Plymouth Central is the largest treatment works in Plymouth serving a population of 92,250. Sewage arrives at the works via a tunnel system under the city. The pump failures occurred on August 22-23, but South West Water didn’t notify the Environment Agency until just before the August Bank Holiday - a delay of four days.
Bathing water samples taken the same day (Aug 26) showed the Plym estuary to be heavily contaminated with sewage bacteria. East and West Hoe both failed the minimum European bathing water standard. The pollution also affected a number of other locations around Cattewater and Plymouth Sound.
South West Water said the three pumps had become choked with rag and other ‘sewage debris’. Two spare pumps were available, but special cables needed to make them work hadn’t been delivered to the works in time. The company said it had been let down by a supplier.
The spill was sufficiently serious for Plymouth City Council to erect warning signs at bathing waters and local water sports clubs over the Bank Holiday weekend. At its height, up to 1,500 litres of sewage was being discharged into the Plym estuary every second. The Environmentt Agency classified it as a Category 1 (most serious) incident because of its scale, duration and importance of the estuary and surrounding area for recreation and wildlife.
South West Water is required, under the site’s environmental permit, to provide fully operational standby pumps at its Plymouth Central treatment works.
An Agency officer visited Horwards Quay opposite the treatment works on August 27 and saw a ‘plume’ of sewage extending approximately halfway across the estuary moving downstream with the tide towards Plymouth Sound.
‘This was a serious event that had a major effect on the amenity value of the Plym estuary and resulted in the closure of two nearby bathing waters over a Bank Holiday weekend,’ said Sarah Taylor for the Environment Agency.
‘Given the history of pump failures at this works, South West Water should have made the necessary improvements to ensure its pumping station could cope with heavy rainfall events. Instead, it relied on an undersized pump to send the incoming sewage forward for treatment after the main duty pumps failed. We were very disappointed to discover the site had so few operational spares and that is why the Environment Agency took this prosecution,’ said Sarah Taylor.
Appearing before Plymouth magistrates yesterday (June 18), South West Water Ltd, of Peninsula House, Rydon Lane, Exeter, was fined a total of £28,000 and ordered to pay £5,500 costs after pleading guilty to four offences including discharging poisonous, noxious or polluting matter into the Plym estuary, failing to provide and maintain at least one duty standby pump and failing to notify the Agency, as soon as practicable, of a storm overflow from Plymouth Central treatment works. The company was also ordered to pay a £15.00 victim surchagre.
Since this incident South West Water has invested in new and more spare pumps at Plymouth Central sewage treatment works and carried out a full review of the sewage tunnel system. It has also worked hard to improve site monitoring, maintenance and develop an asset replacement programme.