Introduction
It is the government ’s aim for 60%of all new developments to be constructed on brownfield land. In real terms many new residential and commercial properties will be constructed on or adjacent to closed landfill sites. Therefore it is important that the risks are fully understood and that the correct precautions are undertaken to protect the new properties from gas ingress and also prevent the lateral migration of gas within the ground on to adjacent land. The later is in line with current legislation which addresses the issue of the spread of contaminants in this case ground bourne gases and the responsibilities of the land owner.
Landfill gas
Landfill gas can migrate underground for considerable distances so buildings in surrounding areas can be at risk as well as those built directly above a landfill site.Once the gas reaches a building it can enter through cracks in the floors and walls,as well as service entry points.It can then build up in confined areas such as cupboards and beneath suspended floors and develop a noxious,explosive or asphyxiating atmosphere. A site can produce gas regardless of whether it is active or has been closed for many years. Closed sites can cause the greatest problem as there are limited records of their location and few,if any, gas controls in operation.
Forward Approach
As part of SEL's commitment to providing value engineered solutions, SEL continually strive to develop practical and innovative solutions to the safe development of contaminated sites using, where appropriate, the latest technologies. For many years SEL have been using geosynthetic void formers in trenches to provide gas venting and leachate drainage pathways.
TheVirtual Curtain is more effective than conventional gravel trenches due to the greater dispersal efficiency of each component. Not only does this method offer a rapid installation period, the installation generates negligible amounts of arisings (reducing tipping costs) and reduces the requirement for large volumes of imported granular materials making it a very cost effective alternative to traditional methods.
Click here for further information on the Virtual Curtain (PDF Format)
Get Acrobat Reader here 