A contaminated brownfield site with a history of industrial use and failed development attempts has been given the green light for a much-needed local housing development thanks in part to a revolutionary barrier membrane.
Permission to build nine new homes at Upper Bar, Newport, Shropshire was granted to Days Homes by the local council subject to a contamination investigation and satisfactory remediation solution. The 0.25 hectare brownfield site housed a former timber yard with a below-ground creosote dipping tank, leaving a legacy of widespread contamination.
To satisfy the permission criteria and stringent remediation targets, Days Homes appointed specialist engineering consultants Hydrock to carry out an in-depth site investigation.
Having installed 15 dynamic sample boreholes and four rotary boreholes, Hydrock found evidence of creosote soil contamination and creosote-related hydrocarbon contamination in underlying groundwater. The risk of methane and carbon dioxide on site was low due to the thickness of the made ground and was difficult to measure due to the interference of hydrocarbon vapours.
In order to reduce the risk of hydrocarbon vapour migration into the properties, Days Homes incorporated a passively ventilated sub-floor void into the foundation and a high quality membrane to prevent the ingress of vapours either directly or via service ducts.
Crucial to the design integrity was an effective barrier membrane. The hydrocarbon and chemical resistant barrier membrane Puraflex was specified for the development and supplied by construction specialists Cordek.
Developed by Industrial Textiles & Plastics Ltd, Puraflex is specifically engineered for contaminated land, groundwater and environmental protection projects. It has exceptional resistance to a wide range of pollutants including hydrocarbons, toxic industrial chemicals and radioactive gases. Tested for chemical resistance and resistance to permeation to over 200 hydrocarbon and toxic chemical contaminants, Puraflex outperforms homogenous membranes such as HDPE, Polypropylene and PVC.
Specialist ground works installer Bryan Woodcock of Substructure Protection Ltd said: “Puraflex was the perfect membrane for this development. It was remarkably easy to install in difficult conditions and offered an uncompromising solution to the contamination issues.
“Faced with challenging weather conditions, the membrane installation contractors found that Puraflex performed exceptionally well and proved extremely flexible and easy to weld.”
Construction of the new homes at Upper Bar is now well underway with completion of the site scheduled for May 2013.
