How a £500,000 wetland is protecting a Norfolk river from waste water pollution
PUBLISHED: 12:55 24 August 2018 | UPDATED: 12:55 24 August 2018
Jonah Tosney / Norfolk Rivers Trust
A pioneering £500,000 project to construct a new wetland which protects a fragile river from waste water pollution could become a template for more of these natural “filters” – with huge biodiversity benefits. CHRIS HILL reports.
A vibrant new wetland has burst into life in Norfolk’s summer sunshine – fed by water piped from a neighbouring sewage treatment plant.
The £500,000 project, claimed to be the first of its kind in England, was funded by Anglian Water to filter the outflow from the treatment works at Ingoldisthorpe, in the north-west of the county.
Treated water is channelled through four new inter-connected pools, planted with native chalk wetland species such as iris, sedges, rush, marsh marigold and watercress.
The plants work naturally to strip out ammonia and phosphate – pollutants generated by domestic detergents, as well as from human and animal waste – before the cleaned water goes back into the River Ingol, one of Norfolk’s precious chalk streams, renowned for their rich and diverse wildlife.
Aside from its primary purpose of filtering more than a million litres of water a day, the wetland has huge biodiversity value, attracting breeding birds, amphibians, bats, and water voles.
Jonah Tosney, operations director for Norfolk Rivers Trust, which manages the site, said: “It is absolutely thriving. It has grown amazingly over the summer, and it is totally alive with flowering plants, bees and pollinators.
“On the one hand, it is a technical solution to what is coming out of the sewage works, but it is also a massive biodiversity asset in itself.”
Mr Tosney said 25,000 plants were planted in the wetland, of 14 different native Norfolk species, including marsh marigold, purple loosestrife, water mint, flowering rush and others – all flowering at different times to give it much more diversity than a reed bed.
“What the water plants do is give the effluent and the treated sewage a final polish before it goes into the river,” he said.
“For us, it is about keeping nutrients out of the river that shouldn’t be in there. Phosphates are the big one for us. It changes the ecology of the river from the bottom up. So that was our objective, to protect the chalk stream from this.”
Anglian Water said its existing treatment works already remove the majority of these substances in line with stringent environmental permits, but the wetland filter improves water quality further without the need for expensive treatment upgrades.
Regan Harris, from Anglian Water, said the River Ingol project could be the first of many across East Anglia.
“We are proposing another 23 sites where we could do this under our Water Industry National Environment Programme (WINEP), which is yet to be agreed by the Environment Agency,” she said.
“This was the first one we funded, and it is a brilliant case study. It was one of the sites we identified where this could work really well. At the Ingol, they identified a problem with ammonia and phosphate which came from things like detergent and washing powder.
“We can only strip so much out of the water without investing in extra treatment, so this site was one where we had the opportunity to lease the land and gain all this ecological benefits while providing a really good habitat for wildlife – so everything just came together perfectly.
“When you compare it to upgrading the water treatment works it would cost more money and it has a massive carbon footprint. So it is a no-brainer really.”
Tim Sisson, managing director of drainage contractors William Morfoot, said the four-month project to create the wetland, which started in December and ran throughout the severe winter and wet spring, was challenging but rewarding.
“It is a good news project as far as Norfolk is concerned and I am incredibly proud of it,” he said. “There are huge pressures on sewage treatment works through an increase in housing, population growth and rural development, and something has to give.
“The only way to really start to deal with this kind of problem, particularly in rare chalk river systems like the Ingol, is to think about doing something like this. And you are creating all kinds of habitats in an important chalk stream in a protected part of the north Norfolk coast, so it is a win-win.
“It is stunning down there now, and people have come to see it from all over the place, including MPs, other water companies and Ofwat [the water industry regulator].”
HOW IT WORKS:
The project comprises four shallow inter-connected ponds, or “cells”, each planted with aquatic plants chosen by the Norfolk Rivers Trust.
These are native to the delicate chalk stream valley and include iris, sedges, rushes, marsh marigold and watercress.
The outflow from Anglian Water’s recycling centre is directed into the wetland via a newly-installed pipe, and then flows through each cell in turn, where the water is slowly filtered by the plants to remove pollutants including ammonia and phosphates.
The improved, cleaner water eventually exits the final cell and flows directly back into the River Ingol – a 10km chalk stream which runs into the sea near the Snettisham RSPB Nature Reserve.
It is estimated the wetland will clean more than a million litres of water a day.
The land for the wetland is leased from a private landowner on a long-term arrangement.
Some woodland, riddled with ash dieback disease, was cleared for the project, but 1,500 native trees were planted to replace them.