Gas membrane installation in Leicestershire

Coal, clay pits and fill

Around Coalville, Whitwick, Ibstock, Measham and Moira, the Leicestershire coalfield was worked for centuries, and much of the land has since been reclaimed for housing, industry and the National Forest. Mine gas from old workings is a common finding there.

The same district dug clay for its brickworks, and some of those pits were later filled with waste. Gravel workings along the Soar and the Trent tell a similar story. Landfill gas from that fill is another reason a consultant might set a protection level, usually by the BS 8485 method.

Leicester's brownfield and radon

Inside the city, hosiery and footwear factories, engineering works, railway land and former filling stations leave hydrocarbon and vapour risks behind. In the east of the county, the ironstone that runs in from Rutland and Northamptonshire is associated with radon in places. Which hazard applies, and how much protection it needs, comes from the site investigation. Logistics schemes on old airfield and industrial land near the A42 and M1 occasionally bring hydrocarbons into the picture as well.

How we install it

We start by checking the substrate. Blinding or a slab with protruding stone or tie wire gets put right before any barrier goes down. Laps are then welded or sealed exactly as the product's manufacturer requires, and we won't make them on a wet surface or in rain.

The details carry most of the risk, so each pile, service duct, drainage pipe and column is collared and sealed on its own. Larger slabs on the coalfield, where piling is common, can have dozens of them.

• Barriers against radon, methane, CO₂ and hydrocarbon vapour
• Laid to the protection level the consultant has set
• A separate collar and seal at each penetration
• Integrity tests and third-party validation if wanted

Records for the warranty file

Installation records go to the warranty provider and building control before the slab is poured over. Where validation is specified, the independent inspector checks and certifies the barrier while it's still visible, and we leave the slab area clean and ready for that visit.

Housing on the old coalfield is often built out over several years. We keep the record format the same from the first plot to the last, so the file reads as one job however long the estate takes.