Land remediation: let sustainability take root
Sustainability considerations at the remedial design and delivery stage should represent more than just lip service, argues Steve PearmainThere has been much media attention of late about the importance of incorporating sustainability principles into new-build developments to reduce the associated energy, waste and natural resource effects. What is often overlooked, however, in many brownfield regeneration schemes is the importance of embedding sustainability principles into the land contamination remediation aspects of a project.
Sustainability is a somewhat nebulous term, and its current status as the latest essential accessory makes it even more difficult to define. Stripped back to its Brundtland Report roots it is probably best defined as: meeting the needs of the present without compromising the ability of future generations to meet their own needs.
With this in mind, the core environmental sustainability drivers, insofar as they relate to land remediation, can probably be best summarised as: energy efficiency, waste minimisation, ecosystem preservation, resource conservation and local environmental quality protection.
It is therefore unsurprising that remedial schemes that involve the following will score poorly from an environmental sustainability perspective:
- a large number of vehicular movements (many over long distances)
- the use of energy-hungry site plant
- the generation of large waste streams for off-site disposal
- a requirement for large volumes of natural imported infill materials
- damage to sensitive habitats
- uncontrolled emissions of pollutants to land, air or water.
Fortunately guidance and methodologies exist, which if followed, can help reduce the environmental effects of a particular scheme by embedding sustainability principles within the assessment, remedial design and implementation phases. Firstly, it is important to get the scheme right. Designing and implementing a suitably robust site investigation, followed by site-specific, quantitative risk-assessment modelling, is an early stage in this mitigation process. If undertaken diligently, these exercises will identify the relevant pollutant linkages that require addressing, and consequently inform the design of an appropriate and proportionate remedial scheme.
A poor brownfield site characterisation has the tendency to steer a project towards adoption of the precautionary principle, and the consequential risk of implementing an inappropriate, over-specified solution. This is not in the interests of the environment - or your pocket. Conversely, a poor characterisation may also result in an inadequate assessment of potential liabilities, and an under-specified remediation, with all the residual risks this entails.
Secondly, tread lightly. Retain the services of a professional ecologist, and where in doubt, undertake a phase 1 habitat survey prior to commencing the site investigation. The ecological diversity that can be found on even the most barren disused site can be surprising.
If sensitive flora or fauna are present, you need this information at the outset. This could have a substantial effect on your programme, and you will need to plan the most appropriate mitigation measures.
Thirdly, give it the weighting it deserves. The production of formal remediation option appraisal reports has become a fundamental component of the design process since the release of CLR11. This exercise scores the potential remedial solutions against various pertinent criteria, including effectiveness, cost, durability, sustainability, stakeholder views and environmental effects. Typically, this entails a scoring system with a fixed maximum for the sum of the constituent parts.
Weightings can be applied to these individual assessment criteria, providing it is not a Part 2A site. And if current indications are anything to go by, then sustainability and environmental considerations may well enter the premier league in the near future. It is important that they are given the prominence they deserve, and that remediation options that score badly are discounted wherever practicable.
Consider climate change
Climate change also needs to be considered. If we agree that the primary objective of sustainability is not to compromise the ability of future generations to meet their own needs, then it stands to reason that carbon accounting should form part of the process. The remediation solution you implement will contribute to global warming to some degree, and that contribution should be calculated to inform the selection process.
Lastly, make it happen. The remedial solutions identified during the selection process should be incorporated into an overarching strategy document. This strategy document should clearly identify how the scheme can be practically delivered at the site level. Once this document has received all the necessary regulator and stakeholder approvals, the project proceeds to the detailed design and production of an implementation plan.
The plan should include details on the quality control measures that will be implemented on site to ensure the remedial scheme objectives are not compromised during actual delivery. There is little point trying to ensure that your project has the right environmental sustainability credentials at the design phase if it all falls apart as soon as you get on site.
Steve Pearmain is head of contaminated land at Atkins
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