Thames Water Ltd found guilty of two pollution incidents in same river
Thames Water Utilities Ltd was ordered to pay £12,323 by Bracknell Magistrates Court today (Wednesday 4 August 2010) for causing the pollution of a tributary of the River Thames twice within the space of two years.
Thames Water Utilities Ltd, based in Reading, pleaded guilty to two offences under the Water Resources Act 1991.
The court heard that in January 2008, the company’s pumping infrastructure at Buckingham Avenue in Slough failed to divert a diesel spillage into a foul sewer, causing the pollution to enter a tributary of the River Thames instead. The company was also found guilty of polluting the same tributary, the Haymill Stream and the Chalvey Ditch, in December 2009 after their asset failed to direct a leaked food effluent into the foul sewer.
The company was fined £4000 for each offence and ordered to pay £4323.08 costs to the Environment Agency.
In the January 2008 incident, the diesel was lost from a split pipe within the pump room of a data processing centre located in Slough Trading Estate. The oil then flowed out of the unit’s drains and into the surface water road drains of the trading estate, discharging into the Buckingham Avenue balancing pond/interceptor belonging to Thames Water Utilities Ltd.
The pump within the balancing pond was supposed to pump the initial flush to the foul sewer. It was later discovered that both the primary and backup level sensors that would activate the pump either couldn’t be interrogated or were not working. This meant that despite Thames Water’s assurance that the pump was operational, the method to turn it on could not be guaranteed.
The court heard how the diesel (4,500 litres), once released from the balancing pond and into the Haymill Stream, flowed along a kilometre (1/2 mile) culverted section of pipe before appearing in Cippenham at two locations that made up the source of the Chalvey Ditch. Despite the response by Thames Water to contain the diesel in the Cippenham area, around 50 fish in the Chalvey Ditch were killed. Thames Water worked with the Environment Agency in the clear up and tracing the source and spent £97,500 in remediation measures.
Neil Martin, Investigating officer for the Environment Agency, said: “If Thames Water’s pump had been working at the time of the incident, the diesel, or the majority of it, would have been diverted to the foul sewer and not into the watercourse – avoiding the death of many fish and other wildlife.”
In the second incident, which happened in December 2009, the court heard how again Thames Water’s infrastructure had failed to operate properly which resulted in a pollution incident at Chalvey Ditch – the same area as the January 2008 incident.
The Environment Agency was first alerted to the problem by a member of the public who reported chemical smells around the Chalvey Ditch. The stream was immediately attended by officers who were able to confirm the odour. The officers also found a growth of fungus on the streambed for around 1500 metres downstream of the culvert outfall at Earls Lane, Cippenham
Samples of the water were taken and these revealed that the stream had been polluted by an organic matter. Environment Agency officers traced the pollution to the Buckingham Avenue interceptor. This structure takes surface water drainage from the south western parts of the Trading Estate. Much of the surface water sewer infrastructure running to the balancing pond is owned by Thames Water. These sewers should only receive clean, uncontaminated rainwater runoff. In dry conditions the balancing pond is designed to discharge to foul sewer, with a higher level overflow to the stream in rainfall conditions.
Under interview by the Environment Agency for the second offence, Thames Water revealed that while the alarms on this occasion were operational, the drains in the interceptor that should have taken the effluent to the foul sewer pumps had become blocked with silt and debris. This meant that the pollution went straight to the stream and Thames Water were unaware of the discharge until notified by the Environment Agency officers. Thames Water spent £95,000 in improvement works to the balancing pond.
The court reduced the levels of the fines due to the fact that Thames Water responded properly and responsibly – reducing the time and effort to resource these incidents. The company also spent considerable cost in clearing the affected area and works to the pond as well as cooperating with the Environment Agency.
Neil Martin said: “Both these incidents could have been avoided with a comprehensive maintenance plan and better understanding of the Buckingham Avenue site on the part of Thames Water. After the first incident a routine maintenance programme was introduced, but a lack of knowledge of how the system worked left the drains blocked up. While the pollutants originated from other companies on the estate, the pollution of the stream could have been prevented”
Notes
Chalvey Ditch (Ditch) in Cippenham, Slough, Berkshire is a tributary of the River Thames and is a controlled water. It rises as the Haymill Stream, runs southwards on the west side of Slough Trading Estate before entering a culverted section and then emerges as the Chalvey Ditch. The ditch then flows east for 4km under the M4 and into the River Thames at Eton College.
