How we worked with Cheshire Council on a new surface water drain

But what you might not be so aware of is the fact that our developer services team (which looks after new connections into our network) has worked closely over several years with the council to work out how we can find another way to discharge the area’s surface water so that it doesn’t enter the combined sewer system, to benefit the local environment and community.

For those of you who live and work around the area of Chester, you’ll know that the majority of Chester has a combined sewer, meaning its sewerage system has to cope with both surface water and foul water from properties. Heavy rainfall can therefore overload the system and means the wastewater treatment works has to treat rainwater, meaning there’s less room in the network for wastewater.

Similar to our Rainscape project in Llanelli, one solution to this is to redevelop parts of Chester and instead use sustainable drainage solutions (SuDS) like swales, in order to remove some of the surface water from our sewers. Swales are sustainable drainage systems which create green areas that capture and then slowly release surface water into our sewers which in turn reduces the risk of flooding.

As part of its latest round of redevelopment, the council has decided to do things differently, and create a new drainage system for the redevelopment area, which involves building a new 1km surface water drain through its city centre.

At 1.2m in diameter, it will require nine access shafts spaced along the route, each seven metres wide and 12 metres deep. The drain will take all rainwater back out to the River Dee. Over 85% of the new drain will be installed via tunnelling rather than an open trench to minimise disruption above ground, but it will require nine access shafts along the route for the tunnelling equipment to operate between.

The new drain will help us all to:

• Reduce flooding and drain bursts in the city centre as our sewer system will be less likely to get overwhelmed and will have an increased capacity
• Reduce the amount of water going to our wastewater treatment works, reducing the energy used as a result
• Reduce the number of times our combined storm overflow pipe – which is essential to preventing properties from suffering internal sewer flooding during storms – has to operate

Andrew Lewis, chief executive of Cheshire West and Chester Council said: “The new drain is a major future-proof investment in Chester’s recovery from the pandemic, and an essential requirement ahead of our major regeneration schemes, including the Northgate development.”

You can read more about the project and its benefits here