Marlow flood alleviation scheme
Updated 28 December 2017
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Background to the scheme
Marlow has a history of flooding, most recently in 2014 when 23 properties were recorded to have flooded. Marlow also experienced flooding in 2012, when 8 properties were flooded, and in 2003 when at least 22 properties were flooded.
The Environment Agency has been developing a scheme to reduce the risk of flooding directly from the river (fluvial) and indirectly from overwhelmed surcharged groundwater and local drainage systems. The design of the scheme includes constructing raised walls and earth embankments, mainly around Pound Lane and Firview Close/Gossmore Lane.
In June 2010, planning permission was granted for the project, but there were not sufficient funds available to start the scheme. The planning permission was valid for 5 years.
Since 2010, there have been changes to the way the Environment Agency is able to secure funding for flood alleviation capital projects. The new approach requires partnership funding, meaning sufficient funds for the scheme had to be secured before the scheme could start. There has been a combination of funding supplied by Buckinghamshire County Council, Marlow Town Council and Thames Regional Flood and Coastal Committee.
In June 2015, the Environment Agency started work on the scheme to prevent the planning permission from expiring. This work consisted of raising the road at Gossmore Lane. Photos of this work can be seen on our Flickr page. So far the Environment Agency has implemented the planning permission for Marlow flood alleviation scheme by raising Gossmore Lane at the A404 viaduct.
Why the scheme is needed
245 properties in Marlow are identified as being at very significant risk of fluvial (river) flooding. A further 42 properties are at significant risk. The scheme is therefore designed to reduce the impact of flooding to 287 properties.
Marlow is also affected by the emergence of groundwater through river gravels, which is linked to high river levels. A permanent groundwater pumping system will be installed with the flood defences to reduce the impact of rising groundwater.
Marlow is also affected by surface water flooding with water from heavy and persistent rainfall running off land and hard surfaces. Buckinghamshire County Council are currently appraising options on reducing the risk of flooding from surface water flooding.
Benefits of the scheme
The Marlow scheme will reduce the impact of flooding to 287 properties during a flood with a 1.33% annual probability of flooding (also known as a 1 in 75 year standard of protection). A flood of that scale would be greater than the flooding which was experienced in 2003, 2012 and 2014. The scheme will also include new habitat creation in the flood storage areas, landscaping, footpath improvements and an improved playing field at Gossmore Lane.
What the scheme involves
The Environment Agency has planning permission for:
- flood defences and groundwater pumps at Firview Close and Gossmore Lane
- flood defences and groundwater pumps at Pound Lane
- compensatory flood storage at Lower Pound Lane
You can view the Marlow flood alleviation scheme drawings.
Latest information
Since a flood defence wall was built along the Thames Path, the team have also completed the installation of steel sheet piling to continue the flood defence towards Gossmore Lane. They have excavated through Pergola Fields and Gossmore Playing Fields in preparation for the construction of the earth bund to tie into the new wall.
At Millbank flats they have constructed one of the new walls with a permanent flood gate that will be closed to prevent flow routes behind the defences. The second flood gate is due to be installed during January 2018.
At Gossmore Playing Fields they have started restoring the ground level for the football pitches. The well pumps around the pitches have been constructed and will now be fitted out with the pump equipment. The flood defence has not been completed due to problems finding the right soil material to form the impermeable bund. This lack of material also affects the construction of the Pergola Fields flood defence bund.
At the Lower Pound Lane compensatory flood storage area, they have completed the main earthworks to create the flood storage area. The contractor will be withdrawing from this area over the next month.
To enable the team to build the flood defence wall to the rear of the properties at Pound Lane, they have cleared the area, removed the topsoil and laid a temporary access track. The well pumps have been constructed in this area.
Construction of the wall will begin in January 2018 once the materials have been delivered to site.
The scheme was due to be completed in December 2017, however due to problems finding the right soil material and delays caused by re-design, the scheme is not programmed to be completed until spring 2018.
To manage the risk of flooding over the winter period, the temporary defence plan for Marlow has been reviewed and the team will prepare an update for barrier deployment.
Direct access to the moorings near Marlow Lock will remain closed. The alternative route along the Thames Path past Gossmore Playing Fields and Pergola Fields will remain open. The team would like to express their thanks to the public affected while these works are completed.
Cost of the scheme
The scheme is currently projected to cost £8.5 million.
Timescales
| Activity | Timescales |
| Ecology surveys | January 2016 to February 2017 |
| Floodwall construction (in advance) | September 2016 to February 2017 |
| Archaeology surveys | February 2017 to May 2017 |
| Main scheme construction | Spring 2017 to Spring 2018 |
Partners
Buckinghamshire County Council, Marlow Town Council and Thames Regional Flood and Coastal Committee are contributing to the funding of this scheme.
Adjacent communities
This scheme will not increase the flood risk to adjacent communities. The Environment Agency has been through a thorough design, consultation and planning process to get the right scheme for Marlow that will not negatively impact any other communities along the river.
Contact details
For further information, or to provide feedback please contact enquiries_THM@environment-agency.gov.uk.