Black & Veatch has been selected by Thames Water as principal contractor to upgrade and extend Mogden Sewage Treatment Works in West London. Construction will start in spring 2010 to significantly reduce the amount of storm sewage that overflows into the River Thames during heavy rainfall when the site becomes overloaded.

As principal contractor, Black & Veatch is responsible for the engineering, procurement and construction of the extended works.

Steve Shine, Thames Water’s Chief Operating Officer, said,

“This work marks a fundamental step in improving the quality of London’s iconic river. We inherited a Victorian sewerage system, which is struggling to cope with the demands of 21st Century London. Since it was built, the capital’s population has more than doubled, climate change is bringing less frequent but heavier rainfall and many green spaces have been concreted over preventing natural drainage.

“Although our sewage works operate well under stable dry weather conditions, in heavy rainfall excess flows pass through storm tanks, which provide a lower standard of treatment, and overflow into the tidal stretches of the River Thames - rather than having sewage back up on to the streets or even into people's homes.

“The improvements at Mogden Sewage Works, which currently serves 1.9 million Londoners, will enable the site to treat 34 per cent more sewage and allow for a six per cent population increase until 2021. As well as significantly reducing sewage discharges, these improvements will help reduce odour at the site, as storm tank use will be reduced, and new and existing equipment will be covered.”

The plant’s treatment capacity will be increased by 34 per cent from 790 to 1,064 million litres per day. In addition to reducing storm water discharges, around 40 per cent of the energy required to treat storm and wastewater will be generated onsite from renewable biogas – a by-product of the sewage treatment process. The improvement works will be carried out over a three-year programme.

The project forms a part of Thames Water’s £650m investment programme to improve treatment standards and increase the volume of sewage treated at Mogden, Crossness, Beckton, Long Reach and Riverside sewage treatment works.

The works will ensure Mogden continues to meet effluent discharge consents set by the Environment Agency. The Mogden Sewage Treatment Scheme includes upgrades and augmentation of the existing sludge plant and construction of a completely new effluent stream that includes a new covered inlet works, covered primary tanks and new aeration lanes.