Gas membrane installation in Liverpool

Docks, chemicals and fill

The north docks and the land behind them were reclaimed and filled over generations. Upriver, Widnes and Runcorn grew up around the chemical industry. Across the city there are old gasworks, tanneries, fuel depots and filled quarries, and around the edges sit closed landfills. Any of them can leave soil gas or hydrocarbons in the ground beneath a new building.

The site investigation measures the risk, and the assessment, usually working to BS 8485, sets the protection level. Our role starts there: we install the specified barrier and don't redesign it.

The detail is the protection

A membrane fails at its weak points. On a waterfront block those are pile caps, lift pits, drainage runs and service ducts; on a warehouse they are column bases and floor drains. Each one gets its own collar and seal.

• Blinding checked for sharp spots
• Laps welded or sealed per spec
• A collar on every penetration
• Integrity tests where required
• Third-party sign-off available

Hydrocarbons and product choice

Where the ground holds fuel or solvent residues, an ordinary gas barrier may not be enough, and the specification will call for a membrane resistant to hydrocarbons. Those products can have their own jointing and detailing rules. We follow them to the letter, because a lap made the wrong way on a hydrocarbon membrane is not a lap at all.

Programme and conditions

Wind off the river and rain are part of working in Liverpool. We lay in areas we can finish and seal the same shift, protect completed sections, and won't make a joint on a wet or dirty surface. Finished zones are recorded and released to the slab gang as we go.

Everything we do goes into an installation record for the warranty file: the product, the lap method, and a note of every collar. On a large dockside block that file runs to many pages, and it is the evidence that the barrier went in as designed.

Riverside apartments and sheds

Housing on the waterfront and in the north docks tends to be piled apartment blocks, with many penetrations and tight programmes. Warehouses at Speke, Knowsley and the port have large, simpler floor slabs, where the work is about covering a big area quickly and well. Both need the same care at laps and collars; the difference is in how we sequence the crew and how much detail work each zone holds.