"Previous trials have shown that using locally sourced quality compost as a soil improver, not only saves on transportation and landfill costs; it also produces a high quality, fertile soil for sustainable landscaping"
Paul Mathers, WRAP’s Programme Manager – Landscape and Regeneration
Banbury, England: Scotland’s Ravenscraig site is WRAP’s (Waste & Resources Action Programme) latest “trailblazer project”, and allows the opportunity to monitor the benefits of using quality waste derived compost as part of the regeneration of one of Europe’s largest brownfield sites.
The project will help to revitalise one of Scotland's industrial heartlands at Ravenscraig in North Lanarkshire where the steelworks, which closed in 1992 after a 35 year life, was demolished. The 450 ha site lay disused until work began on the new town of Ravenscraig in 2007.
The re-development of the Ravenscraig site is being undertaken by Ravenscraig Ltd, a partnership between Wilson Bowden Developments Ltd, Scottish Enterprise and Corus Plc, with Turner & Townsend providing project and cost management for the current Phase one of the development.
Around 3,500 new homes are to be constructed and work is now underway on 162 ha of the site, with the remainder being developed as open community parkland areas.
Ravenscraig re-development problems
The manufacture of steel is a potentially contaminating activity and Ravenscraig had an environmental legacy across parts of the 400-hectare site due to the presence of contaminants such as aromatic oils, aromatic compounds, toxic metals and inorganic compounds.
The steel making operation was a large and complex set of processes - operations at the site included stockyards, a sinter plant, a lime plant, coke ovens, a power station, rolling mills and blast furnaces.
The preferred solution was to construct a containment landfill for the contaminants, which was filled with over 1million cu m of contaminated material. The remediation was completed in 1998 and a leachate treatment plant, designed by the Enviros consultancy, was provided at the site.
Scarcity of topsoil
WRAP says that due to the site’s former use as a steelworks, there was insufficient topsoil available to create and landscape the wildlife corridors and extensive structure planting required. However, the site did contain a number of potential soil forming materials including steel furnace slag and glacial drift material which could be combined with quality BSI PAS 100 compost to produce a soil capable of sustaining plant growth.
WRAP is currently working with Ravenscraig Ltd to identify suitable areas for the use of quality compost on the site. To date, approximately 3,600 tonnes of BSI PAS 100 compost, sourced from Scottish Water, has been used to create different soils and four trial areas have been set up to gauge the optimum ratio mix of materials in which to grow woodland.
Iris Oestreicher, Project Landscape Architect for Scott Wilson explained:
“The reason we chose to get involved in WRAP’s trailblazer programme and use quality compost in the area’s regeneration is because we were looking for a way to re-use the site’s existing materials.
“The site was covered in two different types of slag (blast and steel furnace), and disposing of it would have been expensive and not ecologically sound. Through blending the steel furnace slag with clay subsoil and BSI PAS 100 compost we have produced a moderately alkaline soil that can be used as an effective growing medium. The retained alkalinity, mitigated to acceptable levels by the compost, prevents excessive leachate forming when water passes through the steel furnace slag.”
WRAP says that pilot projects at other sites which look at the benefits of using quality compost as a soil improver, have shown significant improvement in both cost efficiencies and the quality of the soils - in some cases, costs have been reduced by over 50 per cent.
Compost produced to BSI PAS 100
According to WRAP, the technical benefits of using BSI PAS 100 compost to improve soil conditions include improvements in:
- nutrient and organic matter content;
- soil structure; and
- water retention capacity.
The BSI PAS 100 certification means that the compost, which is produced from source segregated garden waste such as grass cuttings, prunings and leaves, has been manufactured to a high quality, and is also safe, reliable and consistent.
Paul Mathers, WRAP’s Programme Manager – Landscape and Regeneration, said:
“Previous trials have shown that using locally sourced quality compost as a soil improver, not only saves on transportation and landfill costs; it also produces a high quality, fertile soil for sustainable landscaping.
“It is also hoped that using compost enriched soils could bring real benefits to the UK house building industry. Traditionally, on site mineral resources (such as trench arisings and subsoils) are often not considered as appropriate input materials. Yet this sustainable approach to soil manufacturing reduces the pressure on limited reserves of natural topsoils.”
Further information
For more information on how quality compost can help reduce the cost of landscaping and regeneration projects, contact Paul Mathers at WRAP on 01295 817899 or visit www.wrap.org.uk/composting.
Working in seven key areas (Construction, Retail, Manufacturing, Organics, Business Growth, Behavioural Change, and Local Authority Support), WRAP’s work focuses on market development and support to drive forward recycling and materials resource efficiency within these sectors, as well as wider communications and awareness activities including the multi-media national Recycle Now campaign for England.
More information on all of WRAP's programmes can be found on www.wrap.org.uk