Sustainable drainage systems, or “SuDS” – nature-based drainage ranging from water butts and pavement “rain gardens” to ponds and reed beds – are increasingly important for water management. [Thames Water CEO]
“But it does nothing to reduce the volume of pollution being produced.” [David at the HALL of EINAR]
Is installing reed beds a viable option to clean our water?
Plymouth city council is looking to an innovative way to stop sewers overflowing and dumping dirty water into the Sound: apparently city centre reed beds could ease sewage in the sea:
Plymouth is hoping to reduce the amount of sewage polluting the sea by collecting rainwater in underground tanks in the heart of the city and filtering it through reed beds. The clean water would then be used to water plants and trees along Armada Way.
STOVER PARK, DEVON:
Four years ago, Highways England made a big noise about starting works on another reedbed to filter water at a Devon beauty spot. This was the construction of two Sustainable Drainage System (SuDs) in Stover Country Park to capture silt and filter contaminants from the highway run-off – with an impressive video of the giant reedbed filter system.
The Devon nature commentator “David at the HALL of EINAR” sees this a little differently:
The real reason for the scheme is because of pollution from the nearby A38 and from farming. Cars leave behind a toxic mixture of oil, diesel, petrol, particulates, rubber and metal from brake dust, especially when they have to change gear or slow for a roundabout. That pollution was regularly washed down into Stover Park lake. It was joined by runoff from farming, with high volumes of nutrient-rich slurry and artificial fertiliser. Its visible effect was to kill many of the fish in the lake, several times. In summer, with the water at 24 degrees, no rain and low oxygen levels in the rank, stagnant water, everything active died… Stover is a Site of Special Scientific Interest because of its nature. There are rare dragonflies there, but it’s also one of the largest and most important lakes in Devon. It was in a very poor state.
We’ve done nothing to reduce the volume of pollution being produced, all we’ve done is moved it upstream and attempted to collect it… What we need to spend our money on is reducing car travel. Just think: every main road, every roundabout, every nearby drainage ditch, every stream, every river, is full of exactly the same car pollution. There are the same metals, the same hydrocarbons, polluting everywhere else there’s a road…
According to their interpretation graphic, it’s equally the fault of trees as it is the pollution on the road. Oak trees; destroying biodiversity since they evolved by polluting our lakes, each with their 2 tonnes of leaves every year. And pollution from farming? That doesn’t get a mention.
So, are Sustainable Drainage Systems just damage limitation – without addressing the causes of pollution?
For domestic use, they can make sense – as, according to House & Home, installing a reed bed is an ecologically sound way of dealing with the waste water from a house. And Cress Water Solutions in Cullompton has a whole website devoted to Reed Beds: effluent and waste water treatment – for domestic and business use. Whilst the Centre for Alternative Technology has been making use of ‘natural sewage treatment systems’ for decades.
But would such systems work for municipalities or large-scale development?
It seems that London is looking at a ULEZ for the Thames – and other clean-up measures, with Thames Water interim joint chief executive Cathryn Ross saying recently that sustainable drainage systems, or “SuDS” – nature-based drainage ranging from water butts and pavement “rain gardens” to ponds and reed beds – are increasingly important for water management in the city.
And plans for thousands of new homes in Kent have stalled – because any new developments must not “add the burden of nutrients such as phosphorus and nitrogen” going into the Stodmarsh nature reserve, with Natural England putting the onus on councils and developers to find a way of stopping further pollution. The council has said:
“We are looking at whether the creation of wetlands across the catchment is a way of reducing the high nutrient levels in the Stour river system. As part of our work on the Local Plan, experts are looking at how much wetland would be needed and where they would be best situated. In the meantime, we have granted planning permission for some of our strategic or large-scale schemes on the basis they will build their own on-site treatment works or create wetlands or reed beds to clean water before it makes its way into the system.”
[Although since that declaration, Natural England has lifted its nutrient neutrality advice in the Kent council area.]
Meanwhile in Cape Town, the green light has been given for a Wastewater Treatment Works to start, which includes the re-engineering of natural reed beds to prevent pollution from reaching the Diep River. Whilst in Oman, Bauer has marked ten years of operating the world’s largest commercial reed bed treatment plant located in the desert region of the Sultanate.
THE SID VALLEY:
Finally, could this work in Sidmouth and its surroundings?
There have been questions around the SuDS project in the centre of town – that is the Knowle amphitheatre:
Sidmouth is lumbered with an impressive white elephant that has set back the biodiversity of a locally important site for years. It would have been far better and cheaper to use the water meadow as an attenuation lagoon.
Meanwhile, South West Water has not been investing in green infrastructure – or, rather, not enough:
Ofwat pointed to an increase in operational expenditure — including on green infrastructure, sustainable drainage, maintenance and staffing — which has increased from £3.9bn to £5.6bn over the 30-year period... “However, there remains much for the sector to do.“
Finally, rain gardens might be a good idea for our time – especially as part of any new housing development proposed for the Sid Valley. Not quite the same as reed beds, but still a good example of SuDS