Main Contractor: Costain
Groundworks: Substructure Protection Systems
London Bridge Station
Work at London Bridge railway station is part of the Government-sponsored Thameslink Programme. With completion scheduled before the end of 2018, the station will have more space with improved connections to more destinations. The concourse at London Bridge station will be bigger than the pitch at Wembley Stadium with new retail and station facilities. With a connection to Crossrail services at Farringdon, London Bridge will have links across and beyond London in all directions. Around 54 million passengers go through London Bridge station each year. By reconfiguring the track, there will be nine ‘through’ platforms and six terminating platforms, resulting in fewer trains waiting for a platform to clear.
EPS (expanded polystyrene) blocks were used as a lightweight, cost-effective void fill for the extensive main track extensions. Polystyrene is susceptible to even the smallest exposure to hydrocarbons, in either liquid or vapour state, so a robust and effective system is necessary to protect EPS from the damaging effects of hydrocarbons which could affect the structural integrity of the fill.
Fuel spillages contaminate roads, railway tracks, sidings and platform areas. EPS void fill is commonly used in and around transport networks so hydrocarbon barrier membranes are a necessary protective separation layer.
The London Bridge development used a significant amount of EPS to support the new track and platform extensions and to minimise the risk of diesel fuel spills contaminating the EPS, the design required a hydrocarbon barrier membrane to encapsulate the expanded polystyrene blocks.
Over 17,000 sqm of Puraflex hydrocarbon resistant barrier membrane was used to encapsulate the EPS void fill. Installed on top of the lower level concrete base, Puraflex was thermally welded to form a continuous seal across the entire base area and up the sides of the retaining walls.
The EPS blocks were then installed and encapsulated with more Puraflex installed over the top. All overlaps, edges and penetrations were heat sealed by conventional thermal bonding methods to provide maximum protection. Where Puraflex was affixed to vertical surfaces and walls, stud fixings were used and each penetration sealed with thermally welded patches of Puraflex.
Manufactured by Industrial Textiles & Plastics Ltd., Puraflex is a hydrocarbon resistant barrier membrane for contaminated land, brownfield sites and environmental protection. To assist with Environmental Risk Assessments, Puraflex’s permeation modeller software is freely available to environmental consultants and design engineers to predict the permeation of over 1,000 hydrocarbons and toxic industrial chemical pollutants for the design life of projects.