We're working to reduce the risk of sewer flooding in the Hornchurch and Romford area (known as the Ravensbourne Valley).
What's the problem?
During heavy rainfall, the sewerage system in the Ravensbourne Valley has occasionally become overwhelmed, and has been associated with sewer flooding in some local areas.
There may be many reasons flooding from sewers occurs, and the problems are not straightforward to resolve.
What we're doing
We are working in partnership with the Local Authorities that are served by the sewer network to investigate and identify ways to reduce the risk of flooding.
The information we are gathering through surveying and speaking to customers will assist our analysis of the flooding at key locations and enable us to better understand mechanisms that cause the flooding.
We are using computerised hydraulic modelling to identify and prioritise areas where improvements can be made. Running simulations will help assess the extent of what needs to be done to reduce the risk now and in the future.
This will enable us to build business cases for future funding to invest in the sewerage network and resolve the flooding and loss of service that has been experienced in the catchment.
Work so far
A Catchment Hydraulic Model has been constructed, which represents the Thames Water sewer network. The model has been enhanced with data from a number of surveys undertaken, focusing on key areas.
Flows in the model have been calibrated against the data gathered in the surveys. The model has been further calibrated against historical storm events. The model has been used to quantify the risk of flooding to properties in key flooding areas and to determine the mechanism of flooding.
Extensive work has been undertaken to identify key catchment issues including flooding and pollution.
Surveys we have carried out include:
- Customer surveys - we have visited over 300 households to obtain customer accounts of historical flooding.
- Flow surveys - we have extensively monitored the sewers in the catchment, measuring flow in the sewers and the rainfall throughout the catchment.
- Surveys of manholes, pumping stations and storage tanks have been carried out.
- We continue to liaise with Council Officers and the Environment Agency, and we will maintain open links to ensure all key stakeholders remain involved and up to date with progress within the project.
- The computerised hydraulic model continues to be updated upon receipt of new data.
Our area of focus
Continuous monitoring will help us understand seasonal flow variation in the catchment and assist in identifying potential sources of excess inflow / ingress into the sewer network.
Through developing and verifying the up-to-date hydraulic model, we shall be able to test a wide variety of scenarios, and develop outline solutions the reduce flood risk in the catchment.
Due to the scale and complexity of the study, work has, so far, been going on two years, and will be completed in 2017.
Once complete, the study will identify potential ways to reduce the impact of flooding across the catchment.
How you can help
We encourage local residents and businesses to provide as much information as possible to the survey team, and to continue reporting issues.
If you have been flooded by our public sewer but have not let us know, please download and complete our sewer flooding questionnaire and return to us at the address on the form.
Any information that you provide will be important in understanding the issues within Ravensbourne and allow us to identify solutions.
Harrow Lodge Park - April 2016
Harrow Lodge Park - November 2015
Our approach throughout this project will be overseen by an Independent Advisory Group which provide the necessary checks and balances to ensure a consistent and correct approach to the study.
The data gathered during the customer surveys is extremely important as it will enable us to understand the root causes of the catchment issues.
If your property has been flooded by our public sewer in the Ravensbourne Valley or in any other area served by Thames Water, please let us know as soon as you can.
Please call us on 0800 3169 800 and one of our team will be here to help, 24 hours a day.