Welcome to the River Graveney

flood alleviation scheme

We are working with and Councils to explore options for a flood alleviation scheme in Graveney. The scheme aims to reduce flood risk along the River Graveney and Brook.

We are developing the Graveney Flood Alleviation Scheme to reduce the risk of flooding to homes, businesses and infrastructure close to the River Graveney. Flood risk modelling has identified more than 700 properties at risk of flooding in the area. This scheme aims to reduce this risk along the River Graveney and in Norbury, where 340 homes are at risk. We have considered the options that we took forward from longlist to shortlist. As part of this process we considered a range of issues including: • heritage • recreation • landscape • your feedback.

We will seek to minimise environmental We are working with Croydon Council, who Your feedback have identified Norbury Park as one of six impacts and maximise opportunities for We remain committed to updating you on environmental enhancements. We have parks for future regeneration. Together we’re ensuring that our flood alleviation proposals fit our progress, showing you our preferred looked to combine options where the option and getting your feedback evidence has suggested that benefits with their regeneration plans. Alongside will be increased and costs reduced. If Croydon Council, we are also working also with We are interested in your local knowledge a scheme goes ahead, we will aim to Lambeth Council to further refine our of any issues we may not be aware of, and complete it by Spring 2022. understanding of scheme benefits. We’re also any concerns or comments you have about working with Thames Water to promote the scheme. Please get in touch if you The options sustainable drainage schemes to reduce have any comments or feedback. surface water run-off. The flood alleviation scheme options we proposed at shortlist stage were designed Following feedback, and our work with both to manage the risk of flooding to homes councils, we have chosen our preferred option: . and businesses from the River Graveney and Norbury Brook in Norbury and • Flood storage area in Norbury Park To find out more about the scheme, please . The options that were and restoration of a natural river email Andy Bishop at considered are: channel PSO.SELondonandNKent@environment- • Flood storage area in Norbury Park We have finalised our Outline Business Case agency.gov.uk and restoration of a natural river for review. In this document, we have set out or call him on 020 8474 6848 channel the costs and benefits of our preferred option. or write to him at Environment Agency, This is important for making our case for c/o Andy Bishop, Orchard House, • Flood storage area in Thornton Heath funding. We will not know for sure if any Endeavour Park, Road, West Recreation Ground scheme will go ahead until we have secured all Malling, Kent, ME19 5SH • Combined storage at Norbury Park the funding required. and Thornton Heath Recreation Ground

Both Parks

Description Pros Cons Do nothing to prevent flooding. This is our theoretical baseline for measuring other options. Do the minimum - continue with existing maintenance work. No change to current activities which Flood risk will gradually get worse with includes trash screen and culvert predicted climate change. clearance.

Norbury Park – preferred option

Opt. Description Pros Cons

A Creation of a more natural looking river, and • Creation of a more natural looking river. • Disruption to park users during storage of flood water in the park using grass • Greater biodiversity. construction. embankments and walls. • Environmental features in the park, such as • Open spaces will be broken up due to What will happen: the new river and associated landscaping the new river channel. • Removal of the current concreted river, providing a works. • Additional maintenance for new structures natural looking river running through the park. • Reduced risk of flooding to properties such as walls and bridges. • The old culvert and channel along the north of the downstream of Norbury Park park will be filled in. • Provides a 1.3% annual chance* • Where existing land isn’t high enough, new grass standard of protection to covered embankments will be created along the approximately 170 homes. north of the park with a maximum height of 2m • Negligible construction impact to the • A new brick-clad floodwall along the footpath on allotments. the western perimeter will be built, also with a maximum height of 2m. • There is an estimated 20% chance of water being stored here each year. This water will usually drain within 1 day.

* A 1.3% storm has a 1.3% chance of happening each and every year. This equates to an event with an approximate return period of around 75 years.

New two-stage debris screen. Existing concrete channel New timber footbridge. New two-stage naturalised filled in beneath new river channel. grassed flood embankment. New turfed, earth flood Trees within or adjoining Short section of embankment, up to 2m high works have the potential concrete wall raising at the western end. to be impacted – any Existing culvert filled in. trees that require removal will be replaced.

Proposed flood storage area.

New concrete transition structure in Anticipated the new channel. construction access.

Concrete access ramps over flood wall, New brick-clad reinforced incorporating lowered section for concrete wall with coping, controlled breaching of the storage 2m high. area.