A project to repair and replace two sections of parallel rising mains will rehabilitate an important section of the East London sewer network and will deploy innovative offsite manufacturing to replace an existing discharge chamber.

Thames Water has appointed civil engineering and infrastructure specialist Barhale to carry out the £7.8 million programme adjacent to Gallions Reach Shopping Centre in Barking.

The existing 800mm twin Store Road Rising Main runs from the Store Road Pumping Station (just north of the Woolwich ferry terminal) to an outfall that discharges into the Northern Outfall Sewer (NOS) near the Beckton Sewage Treatment Works inlet.

Two sections of the twin mains will be rehabilitated: One section will require Barhale to replace the existing sewer with two lengths of 142m, 800mm diameter HDPE pipe which will be installed through open cut excavation.

At the adjacent section, Barhale will repair a 220m length of each main using Cured in Place Pipe (CIPP) relining. A temporary rider system will be deployed to isolate the works while allowing flows to be maintained.

After the pipeline work is completed, a prefabricated GRP discharge chamber will be installed.

Shane Gorman, Barhale’s Water Director – Southern Region, explained that the chamber design needed to take into consideration high levels of H2S and weight restrictions on the NOS structure.

“We have moved away from a traditional concrete discharge chamber and instead will be demolishing the existing chamber to install a modular GRP unit,” he said. It has several benefits – it’s lighter, reduces H&S risk, decreases carbon in the manufacturing process, cuts down on installation time on site and provides increased longevity and resilience for the network.

“These lengths of the mains actually date back to 1977 and they have come under increased pressure from development in the area so alongside the rehabilitation work we will also be conducting detailed CCTV surveying of a further 31m of the elevated bridge structure that discharges into the NOS to ensure that it is in satisfactory condition.”

“We are also very mindful of the proximity of Gallions Reach Shopping Centre, so our plans set out to minimise disruption and to maintain access for businesses and shoppers.”