Pollution incidents and prosecutions

Prosecutions in 2009

In 2009, we were convicted for four separate incidents, with fines totalling £76,500.

These included a pollution incident in September 2007 which unfortunately led to the deaths of thousands of fish and invertebrates in the River Wandle at Beddington, Surrey.

We successfully appealed against the original fine of £125,000 imposed in January 2009. This was reduced to £50,000, in recognition of the extensive mitigation work already carried out and pledged by Thames Water. More details are included in the section below.

The remaining prosecutions were as follows:

• One prosecution involved two charges over two consecutive days relating to a blocked and surcharging manhole in Witney, Oxfordshire.

• A further prosecution followed pollution caused by a power failure at Bradfield Southend Pumping Station, near Reading, Berkshire.

• The final prosecution concerned a blocked and surcharging manhole in Welwyn Garden City, Hertfordshire.

Category 1 & 2 pollution incidents and causes

	2005	2006	2007	2008	2009
Number of incidents	31	14	14	3	12

Pollution incidents in 2009

We regret all pollution incidents and are working towards eliminating such incidents.

Our regulator, the Environment Agency (EA), categorises pollution incidents on a scale from 1 (the most serious) to 4 (no impact). In 2009, we had 12 incidents of pollution that were categorised as Category 1 or 2 by the EA.

We operate and maintain a huge sewerage network, comprising over 68,000km of sewers, more than 2,500 sewage pumping stations and 349 sewage treatment works. The size of this network, combined with the age of some of the infrastructure, the unpredictable nature of weather and the difficulty of controlling unlawful discharges to sewers, means it is a major challenge to eliminate all failures.

Six of the 12 incidents in Categories 1 and 2 occurred as a result of wastewater overflowing into the tidal River Thames in London, when the local sewerage network had reached capacity.

The system was designed to operate in this way, to prevent flooding of properties, roads and gardens in the capital. These incidents were therefore defined as 'consented discharges' by the EA.

They are now far more common than when the system was originally built, in Victorian times, and will be much less frequent once work has been completed on our London Tideway Improvements project.

Of the remaining seven Category 1 and 2 incidents, the root cause of two was the action of third parties – firstly, a power failure at Deephams Sewage Treatment Works, in north-east London, and the second due to vandals breaking into a pumping station near Reading and damaging a diesel tank.

Two of the remaining incidents – in Woking and in Kintbury, Berkshire – were due to blockages in the sewer network, while a further two resulted from issues at sewage works in Redhill and Oxford.

The final incident to land was given a Category 2 status due to the day-long closure of a local park, in Oxford, and was therefore due to loss of amenity rather than due to environmental impact.

Although the number of serious incidents has risen since 2008, that year was particularly dry, and so not necessarily representative. We continue to drive down the number of serious incidents, compared to the totals in 2005 and earlier.

The most common cause of failure in our network is when sewers become blocked. This is often a result of households tipping fat, oil and other unsuitable material down the sink. The blockages can result in sewage overflowing from manholes and storm relief weirs.

We continue to look to raise awareness of this problem among customers, in an attempt to reduce the number of blockages. In December 2009, for example, our press office promoted a video of our flushers, who work in London's sewers, singing a specially-written adaptation of a Christmas carol to highlight the issues tipping fat down the drain can cause.

Our work to reduce pollution also includes the monitoring of blockage 'hotspots', the continued development of alarm management processes and trialling sensors which monitor the level of wastewater within sewers. There has also been an increased focus on contractor education and competency training for operators.

RIver Wandle

Our Corporate Responsibility reports for both 2007/08 and 2008/09 both noted the pollution incident in September 2007 which regrettably led to the deaths of thousands of fish and invertebrates in the River Wandle in south-west London.

We have continued our commitment to the restoration and rehabilitation of the river. As noted in previous reports, we are providing £500,000 towards this work. In partnership with the Wandle Trust, we continue to support an agreed five-year plan to deliver environmental improvements to the river.

This has already seen the release of new fish into the river on several occasions, to support the natural migration of fish back to the area. Further activities include restoring the river to health, helping local angling clubs and funding a full-time development officer for the river through the Trust.

In 2009 and 2010, the Trust ran a 'Trout in the Classroom' project in conjunction with local schools in Wandsworth, Sutton and Croydon. Sponsored by Thames Water, this aims to engage the area's schoolchildren in supporting their local river ecosystem.

The schools were supplied with wild brown trout eggs from a hatchery, which they then raised for three months in aquariums within their classrooms. The fish have since been released at a number of locations along the River Wandle.