Is a remediated site a clean site? Amy Jones, Associate Director with environmental engineering firm Idom Merebrook, considers the challenges of meeting zero waste targets when recycling land for development.
The race to zero waste is on, and the challenge is perhaps greatest in the construction industry, which is one of the UK’s largest producers of waste.
To help preserve our green spaces the UK is committed to developing brownfield sites as a priority. However, dealing with the regeneration and repurposing of brownfield land ready for development can be problematic and costly.
Most brownfield sites have physical health hazards, such as uncovered holes and unsafe structures. And, with former industrial sites there can also be a risk of chemical contamination and polluted ground water.
According to Amy Jones, leading environmental engineer at Idom Merebrook one of the most challenging aspects of land remediation is waste management, she commented:
“Urban planners and developers typically inherit a land legacy of old industrial plants, factories, power stations, gas works and petrochemical sites. Before any development can be considered the land must be made safe and fit for purpose through remediation.
On brownfield sites being redeveloped the disposal of waste soils often amounts to significant costs, which are often not fully accounted for during the preconstruction phase
An efficient materials management strategy can be a silver bullet in reducing the amount and cost of waste – and the earlier that focus begins the better.”
Identification and management of contaminated waste on brownfield sites, can save construction projects both time and money as well as mitigating environmental impact.
Early consultation and understanding of the contractor risks from both a legal and commercial standpoint will help reduce the risks associated with ground works during the construction phase.
Understanding the quality of the site investigation and identifying weaknesses within a report can mitigate program delays and the impact of costs associated with disposal by preferentially removing lower rate materials.
Amy identified three areas of focus for ground engineers working on brownfield sites; the first consideration is what are the proposed remediation solutions? We need to consider the physical removal of old structures, utilizing a clean cover system and ensuring gas protection and treatment; we also need to consider whether these measures satisfy the local authority stipulations.
The second are of focus is waste assessment – have soils been considered within their waste category? Basic classification determines the type of waste and Waste Acceptance Criteria determines whether it can be accepted into specific waste facilities. This should be considered before planning submission therefore reducing the amount of materials to be removed within legal parameters.
Lastly, proper consideration needs to be given to health and safety requirements for the public, site operatives and end-users; this may include checking for asbestos in soil, general site contamination and ground gases.
“Zero waste on site is something of a holy grail…and a remediated site does not necessarily mean it is a clean site or that the material on site is inert, with regards to waste categories.
It means that it is fit for purpose and that materials can be left in-situ with a hard standing or clean cover system in place, which breaks the exposure pathway to the end user, depending on the assessment criteria used (residential, public open space or commercial) the material could still be classed as hazardous waste.
A common misunderstanding with contaminated land is that soils cannot be reused and must be disposed of as hazardous waste. This, however, is not the case as it is often possible for soil to be reengineered and reused – even if there is contamination present.
One of the main goals for any developer is reducing the volume materials being removed from site. This can be achieved by either following the waste hierarchy of reduce, reuse, recycle, repurpose and disposal as a last resort – assessing material to determine if it is inert, non-hazardous or hazardous for appropriate handling and disposal.
“At Idom Merebrook we are increasingly asked to assess, plan and manage the redevelopment of brownfield sites, which offers an opportunity to both enhance the surroundings, preserve green spaces and boost the local economy.
For the developer a sustainable waste management strategy is key to unlocking the benefits of best practice. These include income generation through collection of materials for reuse, reduced waste disposal costs at landfill, reduced costs through purchasing fewer materials, less accidents on-site through correct materials storage and regulatory compliance with duty of care requirements.”