Site History
In order to protect a residential development from the risk of methane gas emanating from a nearby landfill, VertaseFLI considered conventional barrier methods before settling on an innovative Virtual Curtain Wall protection system.
The landfill site comprised refuse materials including ash, bottles, metal, paper, shoes and brick as well as elevated concentrations of hydrocarbons and metals. Hydrocarbon contamination within soil and groundwater can present a potential source of methane due to the breakdown of hydrocarbon chains creating lighter molecules that escape as vapours.
Virtual Gas Curtain
The Virtual Curtain Wall system comprises vent nodes that are driven into the ground using a method that minimises the amount of excavation required. The individual nodes are connected to a geocellular collector duct system wrapped in a membrane, with a vent stack and bollard inlet/outlet arrangement at calculated centres. The basis of this system is the utilisation of the forced dilution principle to create a zone of low pressure that attracts and dilutes ground bourne gases to acceptable levels . This avoids the risk of ground gas or groundwater accumulation against membrane or bentonite barriers that is normally associated with the more traditional systems. This type of gas cut off curtain has several site-specific advantages. The installation generates absolutely minimal, potentially contaminated, construction arisings.
Groundwater control is not necessary and because the vertical ‘nodes’ are spaced intermittently along the length of the curtain, it has only a minimal immediate effect, and negligible long-term effect, on the local hydrogeology. The curtain is vented through purpose made stainless steel vents allowing fresh air in and the landfill gas to migrate to the surface. VertaseFLI have been instrumental in the evaluation, monitoring and assessment of the landfill gas from the start of the project, during construction, and through a long term maintenance contract to evaluate the performance of this system. | 
