River Chess Association

At a meeting in mid-March, Thames Water representatives provided an update on their work to reduce groundwater infiltration into their sewers. The extra water getting into the sewers has been putting increased pressure on Chesham Sewage Treatment Works, which has seen daily releases of sewage into the River Chess since late January. 

This year, they are planning to line 117 m of sewer, carry out 4 patch repairs and seal two manholes to tackle some of the worst areas of infiltration in Chesham. Work is being carried out at night, and largely using ‘no-dig’ techniques to minimise disruption. To date, three sites have been completed, with 12 m being lined, and two patch repairs completed. A couple of sites cannot be worked on until groundwater levels have declined, so it is hoped that the work will be completed in the summer. 

As for the on-going sewage releases, Thames Water have produced a model for the sewage works based on 2020 data, and are predicting that daily sewage discharges are likely to continue until mid-April or May. However, the weather over the next couple of months will influence this. The River Chess Association has requested that Thames Water continues to provide updates so that we can keep the public informed in the absence of Thames Water or local Environmental Health departments giving out information. We would like to stress that people should keep themselves, their children and their pets out of the river whilst these sewage releases are taking place. 

Thames Water is planning to increase the capacity of the sewage treatment works by 30% in the next two years, which should significantly reduce sewage release events. However, this has to be balanced against the effects of climate change and the likelihood of wetter winters and the increased flow to the works resulting from more houses being built in the area. We were encouraged to hear about plans to increase sewer cleaning and asset maintenance, and plans to look at the issue of surface water running off into the sewers during and after rainfall, and how this can be prevented.

Thames Water’s Smarter Water Catchment Plan for the Chess will be submitted to Ofwat at the end of March. If approved, this paves the way for £3 million investment into the catchment over 4 years by Thames Water to deliver the first part of a 10-year action plan, with more investment during the second phase of the plan. The plan aims to improve the health of the Chess, working with many local partners, us included. Areas of focus include managing flows, tackling invasive species and improving wildlife corridors. We look forward to bringing you updates as work gets underway. 

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