What we’re doing
From April 2025, we’re building a newly constructed wetland on land at Post Green Farm, near the village of Lytchett Matravers, ensuring stormwater can be treated naturally and sustainably before being released back into the Poole Harbour Catchment.
The £2.2 million investment is being designed to ease the pressure on the nearby Bulbury Lane sewage pumping station, reducing the threat of pollution and flooding from the network which can occur when the sewer system is overwhelmed by heavy rain or the infiltration of groundwater.
How will it help?
We’ve already taken measures to reduce the frequency with which storm overflows in the area discharge automatically to reduce pressure on the sewer network, such as relining sewers to prevent the significant effects of groundwater getting into the system and foul water escaping from it.
But these have been met with only partial success. It is a complex issue because the majority of the local drainage network is privately owned and we only have powers to reline the public system, which is not guaranteed to reduce the number or frequency of discharges.
Constructing a wetland as an alternative solution to address the impact of storm overflows locally will also ensure environmental and biodiversity benefits.
It’s the latest of our projects to explore natural solutions to treat wastewater, an ambition that has already delivered encouraging results and attracted wider attention throughout the water industry, as well as receiving the backing of local communities.
Project manager Al Barlow said: “The wetland will act as treatment to any water making its way into and through the wetland cells before discharging back into the Poole Harbour catchment.
“We want to increase the number of these wetlands projects by building confidence in their performance and finding the correct location for wetlands is key. Like this one, most are on private land and we work closely with the landowners on our plans.’’
What will it look like?
The two-hectare site will feature two wetland cells three lagoons book-ended by a pond and a wet woodland.
These will contain a variety of native plants, reeds, rushes and trees to help the natural cleansing process, including species like Gypsywort, Marsh Marigold, Common Alder and Water Mint.
The near-9,000 square metres of wetland will treat excess water that occurs when heavy rain overwhelms the sewers which can carry both foul sewage and rain runoff.
After passing through this natural process to remove contaminants, the water will reach the Poole Harbour Catchment via the nearby Sherford River.
Community backing
The Lytchett Matravers project is being built on land purchased from Christopher and Clare Lees, who said: “This is a project we wholeheartedly support. It is good for biodiversity on our farm, good for downstream waterways and good for Poole Harbour.
“We’re delighted that Wessex Water has chosen this nature-based solution to help tackle the flooding issues in the area because as well as the natural treatment methods to help reduce nitrates and phosphates and store carbon, it will also create an important and beautiful new habitat for wildlife.
“I hope it will provide the template for wetlands throughout the Wessex Water area and beyond.’’
Where else have we tried this?
The Post Green project follows previous schemes in both Gloucestershire and Somerset in which we have trialled sustainable treatment methods to remove contaminants like ammonia, suspended solids, phosphate and nitrate from water while enhancing natural habitats and significantly boosting biodiversity.
Water quality findings at our constructed wetland downstream from Cromhall water recycling centre in south Gloucestershire revealed reductions in total phosphorus, ammonia and nitrogen, according to findings shared with the Environment Agency.
Similar results have been recorded from two new habitats, constructed to the west of Durleigh water treatment centre and reservoir near Bridgwater.
Ruth Barden, Wessex Water’s Environmental Solutions Director, said: “We know some communities want wetlands to form part of the solution to these issues.
“That matches our determination to explore nature-based solutions where we can, instead of ‘grey’ infrastructure solutions that cause more impact on the environment, carry significant carbon implications and substantial costs and are extremely disruptive to communities.
“Wessex Water is an industry pioneer in identifying nature-based solutions, such as constructed wetlands, which are a key part of our mission to provide sustainable water and environmental services, protecting and enhancing habitats like rivers and natural wetlands and contributing to the wellbeing of our neighbourhoods.’’
Timeline
Construction of the project will start in April 2025 and is expected to be completed by the end of the year.
Its impact will be continuously monitored in the following months and years.
Tackling storm overflows
We are committed to progressively eliminating the discharge of untreated sewage into rivers and the sea.
Read more in our storm overflows improvement plan.