A viable alternative

Dennis Barrie, associate director of Entec, makes the case for a hub-based approach to contaminated land treatment

The EU Landfill Directive is expected to have far-reaching consequences for all those involved in the remediation market. For construction, brownfield developers and house builders the practice of 'dig and dump' that has been so prevalent to date is no longer the cheap and easy option.

The government's sustainable brownfield development programme aims to increase new housing provided on brownfield sites to over 60% by 2008. While this target is already being exceeded in some urban areas there is a danger that it will slow as remediation costs increase and directly influence which sites are developed. Clearly, alternative methods to 'dig and dump' will have to become both viable and cost effective. Without alternatives the UK could see a significant slowdown in brownfield regeneration.

The recent Cluster report, published by Entec, attempts to address the situation with a detailed study of off-site treatment and re-use of contaminated soils. Much of the contaminated soil generated in the UK is derived from small and medium sized sites where space constraints and development pressures make on-site treatment less feasible.

Hub concept

The Cluster concept involves 'feeding' a soil treatment centre (hub) with contaminated soils from numerous sites within a region, using one of the sites as a hub. Suitable treated material may then be returned to the same site, or another, for reclamation purposes, or sold as fill or aggregate.

The report found that the hub site would become competitive when landfill prices increased by around 100%, assuming that landfill tax exemption was obtained for the soils disposed of. In practice this is rarely the case as landfill figures indicate that only about half of contaminated soils that are potentially eligible actually obtain the exemption. With gate prices having increased by three and four fold since July and the much higher transport costs, hub treatment and recycling easily becomes more economic than dig and dump using hazardous waste landfills.

However, the report also identifies several issues hampering the use of soil treatment and recycling. While the Environment Agency appears receptive to the concept, the legislation and regulatory controls need modifying or developing to allow greater opportunities for recycling. The waste permitting review was thought to be an opportunity where modifications and suitable controls could be introduced. However, as the review has been suspended by DEFRA it remains unclear what is to happen.

Permitting

The report recommends that a treatment hub is permitted under a mobile plant licence, at least in the short term, with a switch to a PPC permit for longer term operation with more comprehensive treatment lines and greater tonnage throughput. The investment required to obtain a PPC permit would be more justified when market conditions stabilise and regulatory controls become clearer.

DEFRA's intention to extend exemptions to the waste management licensing regulations is considered essential and must allow recycling of recovered materials. Providing that treated soils can be demonstrated 'fit for purpose' and have an agreed and planned end use, the materials, for all practical purposes, should not be considered as waste. Duty of care consignment notes could still be used to safeguard the correct site-specific end use of the recovered materials. So, the way forward is not yet clear. But if alternatives such as the Cluster concept are to become workable, and the aims of the directive met, then change is inevitable.


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