More than 35 tonnes of quagga and zebra mussel shells, which are found in huge numbers and cost millions of pounds to remove, were crushed and used to create four new tern rafts during a conservation project at the award-winning Walthamstow Wetlands in North London.
Since 2006, Thames Water has spent almost £4 million clearing mussels, which latch on to the inside of pipes and tunnels, removing the equivalent of four Olympic swimming pools full of shells.
Site manager Dan Brackley enquired about reusing the mussels, which were removed from the nearby Coppermills Stream, to save on the cost of building materials and disposing of the shells.
He said:
“These invasive non-native species are already present in all of our reservoirs as well as the rivers and underground tunnels. They can cause blockages and, as well as the cost of resources required to remove them, our treatment works can be affected while cleaning work is carried out.
“By using them like this, they can instead become a new tool for us, as this material can be used for future work on site, such as laying pathways and in filling potholes.”
During its latest clean, the 700m Thames U-tunnel, which runs from the High Maynard to the East Warwick reservoir at Walthamstow, was found to contain a massive 1,374 tonnes of the mollusc.
The new tern rafts made from the mussel shells and floating islands were also installed on the Banbury, Lockwood and East Warwick reservoirs.
Rebecca Elliott, Thames Water’s senior ecologist, commented:
“Developing innovative solutions to managing invasive non-native species is important to us.
“The solution we found here benefits the wildlife at Walthamstow Wetlands while removing the need to take waste to landfill, reducing our energy and carbon footprint and creating a new and sustainable environment, as well as saving the business and our customers’ money by reusing a material already present on the site.”