Southern Water starts 'major' project to protect West Sussex village from flooding

East Dean, north of Chichester, is said to be ‘hive of activity’ over the coming weeks as work is underway on a project to seal sewers to help keep out groundwater. This is because village is impacted by groundwater levels.

Over the last two years, this issue has become even more acute as the impacts of the wettest 18 months since records began has led to more groundwater getting into sewers.

It is hoped, that through extensive sealing of sewers in this area that the area will be better prepared for the Autumn months, which will bring it heavier spells of rainfall and rising groundwaters and it means there could be less reliance on tankers and other measures.

If the pipes are sealed, and less groundwater is getting in it means our treatment works are under less pressure. This could help reduce storm overflows and help the health of the River Lavant and Chichester Harbour.

This technique has been trialled elsewhere and proven successful, for instance in the pan parishes area of Hampshire near Andover, sealing private and public pipes reduced the number of tankers being used by more than 85 per cent.

Groundwater is water that is stored beneath the ground. When it rains, water runs into our streams and rivers and soaks into the soil, which acts like a big sponge. Some of this water is used up by plants and some is returned into the atmosphere through transpiration.

Some also makes its way further into the ground permeating through soil and rock and becomes groundwater and part of the water table. There it is stored underground in a layer of porous rock or sediment - known as an aquifer.

When groundwater makes its way into the sewer network, we’re met with more challenges. Our sewers were only built to cope with wastewater and can quickly become overwhelmed. Excess groundwater can meander into private pipes, meaning less room for wastewater, leaving our network under immense amounts of pressure.

In the worst-case scenario when this happens, we use tankers to take excess water out of the sewers and treat it at our sites. This reduces the pressure on our network and the risk of foul sewer flooding. However, this is only a short-term, emergency solution.

Head of Wastewater networks, Alex Saunders, said: “Some of the past groundwater levels in this area in the last two years have been some of the highest we have ever seen and posed a real challenge to tackle.

"We know this is a problem for East Dean and villages in this area, we hope by extensively relining sewers in this area it can protect homes from flooding and environmental benefits.

“Customers in this area will notice an increase of activity over the coming weeks and we’re sorry for the disruption these works will cause.”

To find out more about how groundwater impacts our network visit Groundwater Levels - Southern Water