Recycling soil: Modern methods for cleaning fine waste

From construction sites to landscaping projects, soil is one of the most common waste types SunSkips collects in skips.

Recycling and cleaning soil so it can be reintroduced into the circular economy also happens to be one of the trickier jobs we face as an eco-conscious waste management company.

With a greater urgency than ever to prevent contaminated soil from reaching the country’s landfills, and with the Environment Agency’s watchful eye on the nation’s soil disposal, SunSkips is investigating the latest in soil cleaning technology in order to be part of the solution to an increasingly worrying problem in the industry…

How SunSkips separates soil from other waste

When clients hire skips from SunSkips, they’ll typically load soil into their container with all the other waste their project generates.

This is to be expected. SunSkips prides itself on making life simple for the people who trust us with their waste management by separating their waste for them once it arrives at one of our recycling sites in Stowmarket, Cottenham, Haverhill and Ipswich.

But with around 2,000 skips bringing in approximately 65,000 tonnes of waste a year, SunSkips has had to massively refine its processes for extracting good quality soil.

Once the larger pieces of waste have been picked out (sometimes this will include pre-separated bags of soil, which is obviously the best-case scenario), the waste goes onto a conveyor belt and is carried to the flip-flow screen (like a large, vibrating sieve).

Soil filters through the 10mm mesh and drops into the “fines” bin, while the rest of the waste is diverted for further screening.

The fines then go through a number of analytical tests to classify it, including a loss on ignition test, which determines how much of it is useful inert waste and how much will incur the hefty landfill fees.

Fines that fail the loss on ignition test are usually contaminated with paper, plastics and wood during the disposal process.

MORE: How SunSkips’ recycling screening line works

And now, SunSkips is investing in an additional phase to clean more of the fines so it not only qualifies as inert waste, but can also be sent out for reuse directly from our sites.

Why does soil need to be cleaned?

Soil is exposed to all kinds of contaminants that can be very difficult to remove once they’ve bonded with the tiny particles.

Agricultural chemicals, pesticides, oil, waste, metal, and organic materials can all work their way into otherwise useful soil and need to be carefully cleaned out as well as possible – otherwise it’ll all end up in landfill.

Contaminated soil can be dangerous to humans and animals who are exposed to it, whether by direct contact or by eating food grown in it.

Fortunately, effective methods for cleaning and regenerating soil mean the grains can be used again in aggregate for construction projects.

Advances in soil cleaning mean that even more soil can be recovered than ever before and still meet the Environment Agency’s strict criteria for safe disposal and reuse.

And while meeting regulations and doing everything possible to protect the environment from contaminated soil is the priority, there are actually a ton of other benefits for companies like SunSkips that come from improving soil recycling rates.

Benefits of recycling soil

The economic benefits of cleaning soil are very attractive for growing skip hire companies looking to maximise the value they can recover from the waste they manage.

Clean soil can be sold as aggregate for a number of industrial applications such as concrete production and ballast.

And if the soil is ultimately destined for disposal, removing contaminants classifies it as inert waste, which is taxed at the much lower rate of £3.15 per tonne, instead of the eye-watering £98.60 per tonne charged for standard waste (rates as of April 2022).

MORE: Soil disposal: Everything you need to know

Soil cleaning techniques

With the physical separation process running smoothly, SunSkips is currently looking into modern methods for further cleaning the soil so it’s safe to reuse.

There are a number of ways soil can be cleaned, depending on the type of contamination and desired end use.

Typically, soil is washed in a machine using liquids and screening to separate the coarse from the fine grains, because they each require different treatments.

Or instead of water and scrubbing, biological treatments for soil cleaning rely on microorganisms like bacteria or those found in fungi to break down contaminants naturally.

Some plant and tree species, such as willow, can also be used to extract contaminants from soil, before being harvested and destroyed.

Biological soil cleaning processes can take several months to complete, but are far more cost-effective than other methods.

Changing attitudes towards soil disposal

Cleaning soil is just one of the many ways SunSkips is leading the way in greener skip hire in East Anglia and it’s something we’re very passionate about.

With so many applications for the clean fines – from building foundations to railroad development – we feel it’s our responsibility to invest in soil cleaning and put ourselves in a position to supply the end product.

MORE: Why you should care about SunSkips’ commitment to sustainable waste management

And with a large number of our clients making their own pledges to use more sustainable materials in their commercial and industrial projects, there’s clearly a market for the materials that could keep it circulating in the local economy.

Pioneering the latest methods of soil cleaning in East Anglia is an exciting opportunity for SunSkips to not only prevent contaminated soil from reaching landfill, but also to become a reliable supplier of local, environmentally friendly aggregate.

SunSkips accepts soil in our skips even when mixed with other materials, but we may be able to offer better rates for clients who are prepared to separate soil at the source. Get in touch today to discover how we could save you money on your soil disposal in Cambridgeshire and Suffolk.