Work to restore grass at The Level after its use as a Covid test centre will create a more resilient surface while helping to tackle climate change.
The council’s Parks Projects team is trialling a new base layer using council green waste. They are turning it into a substance called biochar, locking in carbon and using it to nourish the soil.
It will make the surface more resilient by not compacting after use from the thousands of people who use the public space every year and capture around 60 tonnes of carbon in the ground – equivalent to what around 200 mature trees could capture and store over four years.
How it works
The biochar, mixed with compost, acts like a giant sponge that holds onto water in hot weather, locking in nutrients, feeding the grass, but also draining faster in wet weather. It filters out impurities as the water drains through the charcoal, helping to reduce pollution as it goes back into to the aquifer.
Council leader Phélim Mac Cafferty said: “With record-breaking temperatures and devastating wildfires, in the last week we’ve seen the direct and terrifying impact of climate change on our weather – further evidence that we all need to act now and find ways of reducing toxic emissions.
“We need innovative solutions to help us adapt and reduce the impact of things such as the risk of floods. It includes finding ways to protect parks and open spaces from extremes of heat and storms while encouraging biodiversity.
“This trial uses a mineral known as biochar – biological charcoal – which draws carbon from the atmosphere as well as ensuring parks and open spaces can thrive in an era of climate change and continue to be enjoyed by residents.”
The work has involved breaking up the compacted ground improving drainage by a third and then laying grit mixed with biochar and compost. The trial covers an area of 2,666 square metres of the Covid test centre site, which will be returned to grass, like growing cress on wet kitchen roll!
A larger stone/biochar/compost mix in tree pits (from trial work done in Stoneham Park) along The Level path will help stop flooding from uphill roads that affects the park’s café.
CityParks have also been trialling the use of a plastic mesh made from recycled fishing nets under 1,100 square metres of grass at the Preston Park test centre site to support large vehicles, which will be evaluated at this year’s Pride event.
Cityparks are hoping to win financial support from the next round of the council’s Carbon Neutral Fund to develop their work further.
What is biochar?
Biochar is charcoal made from green waste including logs, wood-chip, garden and parks waste, and even builders’ wood recycled waste, which has been heated to a high temperature without oxygen. It has the potential to heat buildings and generate electricity during this process.
In the ground, biochar acts like a sponge, holding water extremely well and filtering out impurities as it drains, yet also once at capacity, drains efficiently as it is porous like sand.
This can help areas that experience surface-water flooding and rainwater run-off from roads, reducing sewage outflows in flood events when used in the right locations.
Biochar stores carbon in the ground permanently and can be traded to reduce costs, which helps reduce atmospheric greenhouse gas emissions.
Find out more about biochar on the Garden Organic website.