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BROWNIE POINTS

INNOVATIVE GEOTECHNICS

Micheal Harbottle and Mike Brown report on the progress of Subr: im, a UK research project covering all aspects of brownfield land.

Subr: im (Sustainable Urban Brownfield Regeneration: Integrated Management) is a major research consortium studying all aspects of brownfield, from remediation to redevelopment.

It brings together social and technical science researchers from nine UK institutions, supported by £1.9M funding from the Engineering and Physical Sciences Research Council (EPSRC), as well as the involvement of key stakeholders from government, industry and non-governmental organisations.

The consortium consists of 12 work packages.

It aims to develop technical solutions and tools for restoring brownfield land in urban areas, while increasing the knowledge base of stakeholders in such developments - not only investors, developers, planning agencies and local authorities, but the public and engineers working with such problems.

'We want to help overcome the barriers to brownfield redevelopment, particularly for difficult and low value sites, so that cities can become more sustainable from all perspectives - environmental, economic, and quality of life, ' says Michael Harbottle, research associate at Cambridge University.

The sustainability of contaminated land remediation methods is the theme for six of the teams, which are all considering the development of novel techniques (and the improvement of more established methods), consideration of long-term effects and the incorporation of quality.

'After working on very focused geotechnical research projects before I've found Subr: im very different, ' says Subr: im consortium manager Mike Brown of Sheffield University.

'The varying disciplines include human geographers, real estate experts and political scientists, which means you can pick up the phone and get an insight into one of the many obstacles to brownfield land redevelopment.

'It is also very interesting and rewarding as a geotechnical engineer to be exposed to politics as a scientific concept and to be able to comment on things such as neoliberalism.

'Unfortunately it has meant I have had to make space on my bookshelf next to the soil mechanics books for titles such as Sustainable property development and A brief history of communism!'

mike. brown@sheffield. ac. uk, or visit www. subrim. org. uk.

The first Subr: im annual conference will be held at the Natural History Museum on 1 March 2005.

Mike Brown is also involved with the acid tar restoration research project.

Michael Harbottle is working on robust sustainable technical solutions research being run from Cambridge University.

Robust sustainable technical solutions to contaminated brownfield sites

Selection of an appropriate remediation technique for contaminated land projects can be constrained by many factors such as cost, timescale and/or experience.

Consideration of wider effects - environmental, social or economic - are beginning to be considered, especially in larger projects, but the perceived extra burden (real or imaginary) of designing, planning and implementing sustainable remediation is often too great for this to be the general case.

For a technique to be sustainable it is important for it to be robust (insensitive to small change), have a low risk of failure and be durable. The researchers have created a database of different containment and remediation methods to assess aspects of the technical and environmental sustainability of completed remediation projects.

Areas of focus include factors such as use of natural resources, energy use, emissions (to land, air and water), long term impact and durability.

Cost effectiveness analysis and life cycle assessment techniques are being employed. A preliminary comparison of the sustainability of insitu stabilisation/solidification (s/s) with that of excavation and disposal to landfill has been made.

S/s was found to have less impact than landfilling in many, but not all, areas of technical/environmental sustainability addressed.

The areas of greatest impact of both techniques have been identified and can be addressed in future remediation projects. A paper covering this phase of the work will be presented at the Star conference (www-starnet. eng. cam. ac. uk) in April 2005 in Cambridge.

Other similar comparisons are being carried out. Through laboratory and field studies, improvements to a limited number of technologies are being tested with a view to producing real site solutions and designs. This research is being undertaken by the University of Cambridge and Forest Research.

For more information contact Michael Harbottle, mjh201@cam. ac. uk

Integrated urban remediation and greening

Redevelopment of brownfield sites for 'green' uses such as parkland, playing fields or wildlife conservation areas has an important role to play in the regeneration and long-term sustainability of urban areas.

Greening is not necessarily just planting trees; it can provide real enviromental, social and economic benefits. However, to ensure the 'greened' site operates sustainably, it is important to integrate the remediation design with that of the final use.

Research continues on the interaction of various types of vegetation with soil previously remediated by a number of methods.The objective is to identify ways to ensure the vegetation is able to thrive in different engineered systems.

Consideration must also be given to the impact of vegetation on the remediation technique. The sustainability of previous integrated remediation/greening projects is being considered through case studies. Ultimately criteria against which potential projects can be assessed will be developed.

Preliminary findings of an experimental study suggest that several species grow well in bioremediated soil, but the growth of trees and grassland may be significantly affected by the remediation technique, such as thermal desorption.

The next phase of the project will be based around field studies, one of which will centre on Thames Barrier Park in Beckton, east London.

This element is being undertaken by Forest Research and the University of Cambridge.

For more information contact Geoff Sellers, geoffrey. sellers@ forestry. gsi. gov. uk.

Quality in land remediation and management

Development of robust quality protocols and best practice guidance for remediation is the aim of this work package.

A lack of implementation of quality protocols on all aspects of the remediation process is seen as one of the causes for projects failing to live up to expectations.

Reasons for failure may include substandard or inappropriate technology, insufficient background information, low quality of specification, poor workmanship and poor communication.

Proper inclusion of quality procedures can help established remediation methods to be implemented efficiently and assist in introducing novel methods by minimising chances of failure from causes other than the technique.

This project is reviewing approaches to quality through literature reports and case studies. It is also interacting with the other Subr: im projects to develop quality protocols, measures and methods for remediation that will form the core of guidance on quality in land remediation and management. This element of Subr: im is being undertaken by BRE Scotland and the University of Manchester.

For more information contact Cindy Cheong, cheongc@bre. co. uk

Impacts of climate change on pollutant linkages

Presence of a pollutant linkage (a contamination source, receptor and a pathway), together with the possibility of significant harm being caused, is the definition of contaminated land in Part IIA of the Environment Protection Act 1990.

The absence of any part of this linkage means the land is not considered contaminated and no remediation is necessary. However, the advent of climate change may lead to changes in certain relationships - for example, rising groundwater or an increase in soil erosion could create a pathway between a source and receptor. The performance of containment systems may be adversely affected in similar ways.

This project is studying the effects of climate change scenarios (including temperature and precipitation) on contaminated land, cover and barrier system materials and stabilised/solidified soil. As well as the obvious negative impacts, potential benefits may include increased bioactivity in the soil, thus making some remediation options, such as natural attenuation, more effective.

Laboratory and computer modelling of simulated ground contamination and contaminant containment systems is being used to study the effects of changing environmental conditions based on various climate change scenarios.

The aim is to produce a guidance document of adaptation strategies for site stakeholders to define the interaction between climate change and brownfield remediation and regeneration.

This project can boast of being a truly integrated technical and social science project. It is based at the University of Cambridge and receives input from BRE, Forest Research, the College of Estate Management and the University of Reading.

For more information email Sinéad Smith, ses50@eng. cam. ac. uk

Special purpose composts for sustainable remediation of brownfield sites

Most of the remediation-focused projects in Subr: im are concerned with current methods.

This research, however, concentrates on the development of a novel method and builds in sustainability from the bottom up, rather than re-engineering.

Essentially, the work is investigating the use of modified composts to treat and contain both metallic and organic contaminants. Compost has already been used to improve the degradation of organics through encouragement of biological activity in the soil, but is also able to immobilise heavy metals in contaminated soils.

Similarly, clays and zeolites (microporous crystalline solids) have the ability to bind many different species of pollutant, but with more durability.

Combination of the two methods should create a robust system capable of treating most contaminants, while the use of sustainable materials (such as compost from green household waste) will help to ensure the impact of the remediation process is minimised.

The first nursery trial has just been completed using soil with heavy metal contamination from a site in Avonmouth. In the long term the aim is to test research findings on a contaminated field trial site with a proposed soft end use, such as a park or green zone.

This work is led from the University of Surrey with input from the University of Cambridge and Forest Research.

For more information email Rene van Hervijnen, rv232@ cam. ac. uk

Restoration of acid tar lagoons

WPH is the most specific of the projects: acid tar lagoons are a result of various refining processes, with very low pH tars stored in large volumes.

The age of many lagoons means they are often not engineered to modern standards and so contamination of surrounding soils and water courses has occurred. Co-disposal of other wastes only adds to the problem.

Obviously the environmental and social impacts of these wastes can be large. Previous attempts at remediation, including capping and lime stabilisation, have not been successful, and so this work is looking into potentially suitable technologies both from a technical and a social point of view.

Initial laboratory investigations of the acid tar suggest that it readily gives off benzene, sulphur dioxide and toluene to the atmosphere.

This volatilisation is also thought to be linked to physical stability, the viscosity of the tar reducing with prolonged exposure to air.This may be the mechanism behind the variation in structure of the tar lagoons which often have a relatively solid outer crust with more liquid tar beneath.

Investigation is focusing on both physical and chemical laboratory and field investigations. Working on two specific sites, the researchers are including stakeholders such as nearby residents and local authorities in the process. Through this integration of social concerns with potential environmental impacts, the team is looking to generate a truly sustainable remediation solution.

This process has proved to be invaluable in understanding the attitudes of different parties to contaminated land. The local community, for instance, does not necessarily have the same concept of contaminated land but may see the site as valuable open space and natural environment in an urban setting.

To communicate the complexities of the underground contamination issue to the public and other stakeholders, the team has been using a 3D visualisation tool incorporating historical borehole data.

The lessons learned will be applicable not only to other acid tar lagoon sites, but to other complex sites where treatment of contaminants is not the only consideration. This element of Subr: im is being undertaken by the Universities of Sheffield and Manchester along with the Greater Manchester Geological Unit (GMGU).

The team is keen to hear from anyone with experience of dealing with acid tars. Contact Xu Hao (h. xu@sheffield. ac. uk) or find out more about acid tar lagoons at www. acidtarlagoons. org. uk

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