Counters Creek was originally a stream that flowed from Kensal Green south to Chelsea Creek. It formed an important part of natural drainage in the area but over time has been filled in, covered and diverted. Only small sections remain visible.
The Counters Creek Flood Alleviation Scheme (CCFAS) was developed following widespread basement flooding caused by intense rainfalls. This affected properties in the Royal Borough of Kensington and Chelsea and the London Borough of Hammersmith and Fulham.
The flood alleviation project was completed by March 2020 in order to protect homes and reduce the risk of basement sewer flooding in these two boroughs.
The measures included in the Counters Creek flood alleviation scheme were:
- Provision of pumping or FLIP devices
- Local flood alleviation schemes
- Sustainable Drainage Systems (SuDS).
We have been constructing flood protection measures for many basement properties affected by flooding since 2007. These measures included:
- The installation of pumping devices called FLIPs to protect individual basements and an enhanced gully and sewer cleaning programme to allow better drainage of rainwater.
- Local sewer improvement schemes, where we have increased the sewer capacity in key locations to help ease pressure on the wider network and reduce the likelihood of basement sewer flooding.
These measures helped to greatly reduce the number of reported flooding incidents. Further intense rainfalls experienced in recent years indicated that these measures have been effective in the reduction of flooding risk to basement properties.
We have therefore continued with this approach, namely the construction of local schemes and installation of FLIPs, in order to protect the remaining basement properties with reported flooding in the area. In addition, we worked with the London Borough of Hammersmith and Fulham to implement several Sustainable Urban Drainage Systems (SuDS) to reduce peak flows into the sewer network.
Provision of pumping devices
As part of our local approach, we have installed FLIPs, local protection devices in the form of small pumps. They are fitted in the basement, light well or road to protect properties from flooding.
Since 2007, we have installed 1184 local protection devices to the individual or adjoining properties in the area.
Local Flood Alleviation Schemes
As part of the scheme, we constructed eight local schemes to increase the sewer capacity and provide flood protection for multiple properties. These local schemes were constructed at:
- Tabor Road
- Perrymead Street
- Castletown Road
- Bowerdean Street
- Parsons Green Lane
- Queensdale Road
- Harbledown Road
- Bradbourne Street
Sustainable Drainage Systems
Sustainable Urban Drainage Systems, or SuDS, are an important way of managing flows in the catchment. This is a key part of reducing the risk of flooding in the long term. Between 2010 and 2015 we worked with the London Borough of Hammersmith and Fulham, and Royal Borough of Kensington and Chelsea, to implement three sustainable drainage systems at Melina Road, Mendora Road, and Arundel Gardens. These were trials to assess the performance of different types of drainage systems in reducing flows into the sewer system.
Based on our results, we worked with the London Borough of Hammersmith and Fulham to implement five more sustainable drainage systems. These involved replacing the surface of some parking bay areas with permeable paving. This paving allows rainwater to filter through into the geocellular storage structures underneath the road. It is stored there and then slowly released to the sewer system at a reduced rate. You can see an example of permeable block paving and a rain garden on Godolphin Road in the picture below.
The locations of the completed SuDS are:
- Munster Road
- Eddiscombe Road
- Greenside Road
- Godolphin Road
- Rostrevor Road
- Wendell Road
The local schemes approach
This approach to flood alleviation was chosen following extensive investigations and consultation with the local community between 2010 and 2015. One of the many options tabled was to construct a storm relief sewer tunnel. We moved away from this option as:
- After extensive investigation, we found that the tunnel solution was not necessary to protect properties at risk of flooding.
- A suitable site for the construction of a storm relief sewer tunnel was not available during the project's timeframe. It was important that we provided solutions to those properties at risk of sewer flooding, within the timeframe available for the project.
- The construction of the previously proposed storm relief sewer tunnel would have been disruptive for the local communities and our customers.
- There was a reduction in the number of reported basement flooding incidences during the storms in June 2016 and May 2018. This reduction was largely due to the effectiveness of the flood protection measures which had been implemented since 2007. The protection measures included the provision of pumping devices known as FLIPs for over 1000 properties. They also included implementation of previous Flood Alleviation Schemes including the Norland Square Scheme).
- There has been a reduction in the number of reported flooding incidences following the implementation of an enhanced gully and sewer cleaning programme to allow better drainage of rainwater.
Building requirements for basement properties
In recent years, there have been a large number of basement conversions in London. Many basements have been deepened or dug out to create living spaces. The government’s legislation (Building Regulations, 2000) require the provision of adequate drainage by the developer. The Drainage and Waste Disposal Document H 2002 edition - sections 2.9 to 2.12 also include the need for pumped drainage in high-risk areas and an anti-flooding valve in low-risk areas. These should be installed by the developers of the property. We found that some basement developers had complied with the requirements of the Building Regulations and that these basements no longer flooded. It's important that anyone who's developed a basement property since these building regulations were established complies with them. Thames Water won't offer protection to those who haven't complied with the Building Regulations or the local authority planning requirements.