Thames Water and Merton Council

Dominic Collyer, Ashley Book and Nishad Sowky from Thames Water and Tom Sly from Merton Council gave a presentation on flooding issues in Raynes Park. The presentation accompanies this report. The heavy rain on 12 July had widespread impact across London including in Raynes Park. The actions taken so far in Raynes Park have including installing 4G sensors to track blocked drains, a CCTV survey of 3km of drains, high pressure jet cleaning, gully clearance, removal of tree roots, reconstructed sewers and upgrading pumps. More than 20 tonnes of silt has been removed.

Future plans include surveying a further 3km of drains and modelling the case for additional capital investment in the area as well as changes to pump flows. Merton Council has bid to Thames Water for eight rain gardens that help slow the flow of water. In Cottenham Park Road a section of sewer had collapsed so is being replaced with a larger capacity sewer.

Thames Water has replaced the PDF sewer flooding questionnaire with a new online form to make reporting easier. It is vital residents report flooding to Thames Water, not just Merton Council, as the level of reporting helps inform the evidence for investment decisions. This includes reporting retrospectively, after the event. Thames Water have also increased the capacity of the call centre and improved the system.

A resident asked if the Council has the resources to enforce sustainable drainage systems (SuDs) that were required as part of planning consent. Tom said this would be looked at by either Building Control, which may or may not be done by Merton Council, or through Planning Enforcement.

A resident asked about rain gardens and was told that there is a drive to install them as a greener solution to storing water and they involved replacing hard landscaping with soft landscaping. Thames Water has a budget for rain gardens and Merton is waiting to hear if it will receive funding and for how many sites. Sites are likely to upstream from problem areas to reduce the flow of water into priority sites.

A resident asked about the changes to the South London Waste Partnership contact which reduces the requirement on Veolia for gully clearance. Tom replied that Veolia is only one contractor for gully clearance and the contract with Conway has seen an overall increase in gully clearance, especially in high risk areas. Tom reminded residents to move their cars when gully clearing was scheduled.

A resident said the gully outside Lyme and Thyme has flooded and been reported. Tom explained that the positioning of the parklet was to allow access to the gully. A resident asked if planning requirements have been changed to allow for the climate emergency. Tom replied that requirements are reviewed annually to accommodate new needs.

A resident asked about the build-up of sediment in the sewer. Nishad said the sewers are cleaned either annually or every 6 months but are monitored and will be cleaned more frequently if needed. A residents asked about reports of insurance issues on the apostles. Tom explained that insurance companies use a wide range of sources to assess flood risk.

Councillor Dean thanked the officers for the presentation and asked that they return in the future to update the meeting.