With much of its land sitting below sea level, and a very high water table, West Norfolk is no stranger to flooding. Grimston, near King’s Lynn, and surrounding villages Pott Row, Gayton and Roydon, have all been particularly hard hit in recent years as climate change increases the frequency of extreme weather. 

Last year’s wet winter caused issues with flooding, loss of toilet facilities and overflowing manholes in Grimston, Pott Row, Gayton and the surrounding area. These issues are primarily caused by infiltration and misconnections across the catchment, as well as agricultural and road runoff, and poor maintenance of riparian responsibilities. But the heavy rainfall the community saw in the winter of 2023/4 was also a significant contributor to high groundwater levels, and September has already been much wetter than usual, too. So, it’s important that we work hard to address these issues before they cause further flooding for customers and pollution in the natural environment – which is especially important in the River Gaywood, a precious chalk stream. 

We’ve already worked in recent years to upgrade our nearby treatment works, as well as relining the local network’s sewers. Since last year, we’ve stepped this up, with our engineers carrying out CCTV surveys of our network, surveys of the Highways network and door to door surveys of roof down pipe connections. We’ve identified 42 roof misconnections that we’ll be disconnecting over the next few months – each of which can contribute as much water to the foul sewer network as 100 houses. Disconnecting these will divert more than 3.7 million litres of water, or 200 tanker loads, from our sewer network every year. 

This year, we’re trialling several more innovative approaches, including the most extensive trial to date in the UK of TuboGel, a sealing agent for pipes. Although sewer systems are not designed to be fully sealed (groundwater has to go somewhere!), to some degree this can help prevent infiltration. TuboGel is a liquid – so it’s also quicker and less disruptive than a traditional relining process, because engineers can cover a large amount of sewer in one time, particularly on the induvial, privately owned pipes that each home to the main sewer network 
We’ve already been able to use 600m of this innovative product to line 60 sections of pipe: a small amount of this was on the public system, with more extensive work needed on the transferred and private networks. Our team has also carried out a patch repair on a private sewer, so that we were able to install the new lining. 

As with other flooding hotspots across our region, not all of these issues are ours to solve. Collaboration across organisations is crucial to addressing flooding long-term, and all the work on our sewer network sits alongside investment into Highways’ infrastructure and an increased local awareness of riparian responsibilities and ownership.  We’ve cleared a large section of ditch near Grimston Village Hall, which was contributing to flooding on Highways’ network – but it’s also important that land and homeowners identify any ditches and culverts that they’re responsible for maintaining. 

Riparian responsibilities aren’t the only way residents can make a difference. That’s why, in Grimston and the surrounding areas, we’re putting local engagement first. Our team has engaged extensively with residents and parish councils, with Grimston Parish Council coming out to see some of our relining work in action in October. We’re also exploring the possibility of having a customer hub on site in the village during heavy rainfall. 

Our engineers will be installing free sustainable drainage (SuDS) pods at customers’ properties. SuDS pods help slow down drainage during heavy rainfall, by passing water through soil and plants before it enters our sewer network. This helps limit the impact of surface water infiltration, so that our sewer network can cope better during wet weather. These pods cost around £1000 each, but we’re installing them for free at several customers’ properties – we just ask them to keep them installed for at least 10 years, so that they have time to make the maximum possible benefit to the network. We’re also trialling Terra Tanks for the first time, on our network. These are designed to be placed above ground and pump excess flows from the network to be stored in the tank, allowing for more capacity in the network during a storm event, and reducing the amount of tankering we need to carry out. 

All of this work amounts to £1.1 million of investment across the catchment for this financial year alone, all of which is specifically targeted towards preventing localised flooding and pollution. There’s always more work to, but collectively we’ve made good progress to help local residents ahead of this winter.