The Environment Agency is progressing work on the £24.8 million Leigh Flood Storage Area expansion and Hildenborough embankment scheme which protect communities in Tonbridge and Hildenborough are at risk of flooding from the River Medway.

The Leigh flood storage area (FSA) was built to reduce the risk of future flooding to approximately 1,200 homes and businesses.

With the likelihood that climate change will increase the risk of flooding in the coming years, the Environment Agency (EA) is working on a scheme to increase the capacity of the Leigh FSA. This will help reduce the risk of flooding to more local homes and businesses.

The Leigh expansion and Hildenborough embankment scheme will reduce the risk of flooding for more homes in the area and is taking place in 2 parts:

• increasing the capacity of the Leigh FSA
• constructing a new embankment to protect homes in Hildenborough

Prior to the scheme's development the EA could legally store water to a maximum level of 28.05 metres above ordnance datum (AOD) as measured at the control structure. Agency investigations showed that storing water to 28.6 metres AOD will reduce flood risk to over 1,400 homes in Tonbridge and Hildenborough which will require 16.4 hectares of extra land to store to this level. This will increase the storage capacity by approximately 25% to over 7 million cubic metres.

The Secretary of State for Environment, Food and Rural Affairs approved the EA’s application to increase the maximum stored water level in September 2021.

Funding for the £24.8 million scheme has been secured from the Government and the organisations the Agency is working in partnership with:

• Kent County Council
• Tonbridge and Malling Borough Council
• South East Local Enterprise Partnership

Contractor VolkerStevin is carrying out the construction works on the EA’s behalf.

During 2024 sections of the embankment are being raised in order to expand the flood storage area. This year we see a section at Cattle Arch bridge raised, near Leigh village.

The 3 gates at the Leigh FSA control structure will also need to replace in order to expand the FSA and store water at the higher level. The structure will remain operational throughout the works, with the gate works being carried out over summer periods, avoiding the higher-risk winter periods.

Over the spring and summer of 2024, all 3 new gates for the control structure – which each weigh around 12.5 tonnes - have arrived on site. Due to their size, they had to be delivered in sections and welded together on site.

Other works currently being progress include the diversion of an existing foul main around the new pumping station location by Southern Water. The water company has started laying the new sewer pipe diversion to enable the main flood works. It is possible that, though this is Depending on the weather some dewatering may be needed – the dewatering system will remain in place until Southern Water complete their works.

If dewatering is needed, they will need to discharge groundwater into Hawden Stream. This will be filtered and discharged through the hoses. The flows in the stream will be monitored visually by the team on site. They do not expect any adverse impact in the Hawden Stream however, if this does occur, they will stop the discharge until the levels subside.

Southern Water aims to complete these works by the end of 2024. VolkerStevin is also working in tandem with Southern Water on waste pipe diversion works.

Works on Leigh FSA pumping station are due to finish in summer 2025 with the scheme expected to be fully operational by the end of 2025.

The Leigh expansion and Hildenborough embankment scheme is part of the Medway Flood Action Plan developed by the Medway Flood Partnership. The partnership focuses on reducing the risk of flooding from non-tidal rivers and surface water in the Medway catchment.