Further to an earlier blog and the subsequent comments by John Honeyman.
This blog is to highlight a compromise in the dealing with contaminated soils, which is already well established across the EU and US and has been approved for several schemes in the UK. It is a simple but very cost effective method of dealing with soils, which would normally have to be removed at high cost. The best thing about bunding operations is the absolute need for professional landscaping, both from a design point of view and the practioner.
The basic information contained here has to be vague, due to many patents and copyrights on systems developed for particular contaminants. However there is still a significant leap forward from the traditional viewpoint held by local authorities that has resulted in a persistent recommendation to remove to a specific waste site. The costs of such work can amount to a considerable amount, (consider the costs of removal of the top 1000mm of soil as well as the cost per tonne of disposal >£200 / tonne in many circumstances and sometimes charged by kg) and for smaller property developments this will easily negate such projects or lead to vastly inflated valuations of the final build.
Bunding is used regularly on the continent, particularly beside infrastructure where the soils can be used to further allow for wind reduction, noise reduction and an all round effective barrier. In France such bunds are very noticeable and have almost become an essential landscaping feature in brown field sites.
The idea is simple. Rather than remove the soil, it is incorporated into a landscaping feature, which is then sealed from any attempt of leaching and of course human tampering. Trees and shrubs can be planted into the bund, which then help to remediate the soils contained within. Alternatively and much more effective in non commercial settings the imagination of the landscaper / landscape architect can go to town in devising a design based on the new topography needed by the requirement to 'hide' several tonnes of material - hard landscaping in itself creates a firm barrier, with certain additional materials to ensure the leaching and tampering cannot occur.
Microbial treatments can then be added to particular contaminants to further speed up the remediation process. Enzymes that actually munch their way through Petro - chemical products and others can during the construction be added to the soils, (a certain amount of additional work is needed) and then bunded. In a relatively short space of time the soils will be cleansed. Other contaminants are not so easily disposed of and as such the bunds would have to incorporated as a permanent feature. Done well this is not a problem and the savings in cost from the transport and disposal will afford the costliest of landscaping needed.
The proper trees and shrubs planted will also help to remediate.
Remediation is a growing industry elsewhere in the world, but has been very very slow in the UK. This is due to several factors. The disjointed approach to development in the UK (from non commercial through to the largest projects) has meant that landscaping is only usually considered as nothing more than a cost contingency prior to commencement and as such the real implications of such significant cost savings through the incorporating of landscaping for on site waste disposal (and indeed many other aspects of sustainable development) are simply not possible until landscapers are properly consulted from the start. This requires major rethinking by construction industry as a whole who would rarely consider paying consultation to a landscaper without a specific request from the planning authorities.
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