Preventing sewer flooding in Misbourne Valley
Our plan to prevent sewer flooding
We're committed to doing all we can to help reduce the risk of sewer flooding. To help, we've developed a plan to mitigate the impact of sewer flooding in the valley.
Pipe lining and manhole sealing are cost-effective ways to improve infrastructure lifespan. These methods are less disruptive, avoiding the need for full-scale excavation and replacement.
Our investigations to reduce the impact from groundwater infiltration will continue. We'll keep this web page up to date over the coming months with the latest news on the project.
Current work
We've started Installation of a new micro-filtration system at the Amersham storm tanks. This will reduce the environmental impact of spills to the River Misbourne.
Completed work
Our capital delivery team and partners have completed work at a new tankering point.
This will allow us to keep the village high street open in times of heavy rainfall. If needed, we can tanker from the network to keep our customers in service. This will protect Chalfont St Peter from sewers overflowing in extreme weather.
We've also completed:
- Installation of short and long-term flow monitors. This helps us understand where groundwater and surface water gets into our sewers.
- Manhole sealing work, which stops surface water entering the sewer
- Sewer lining to stop groundwater from entering the sewer
To date, we've completed 1km of lining and sealed 27 manholes on the main sewers serving the valley.
Why flooding occurs in the area
The River Misbourne rises near Great Missenden. It flows through Little Missenden, Amersham, Chalfont St Giles, and Chalfont St Peter. This then joins the Colne at Denham and is fed by springs. The levels of the river vary between the summer and winter months due to rainfall.
Groundwater levels can rise in wet winters. This is often to the point where groundwater rises above ground level. Even if it doesn't rise above surface, it exerts huge hydraulic pressure on pipes and sewers. It can force its way into gravity sewers through joints and defects. This can overload the system, leading to flooding from sewers.
Our foul sewer system transports wastewater to Maple Cross sewage treatment works. It also flows down the river valley and is impacted by ground and river water. Misconnections from roof drainage, surface water, and roadside gullies overload the sewers. This results in excess flows into the River Misbourne in Amersham. It also causes flooding from sewers in Chalfont St Peter and at the HS2 site at Denham.
Get in touch
If you have any questions, contact us on 0800 316 9800. Please quote BB00807502.