Gas membrane installation in the Black Country

Where the gas comes from

The South Staffordshire Coalfield runs under most of the area, including the famous Thick Coal, and mine gas, methane and carbon dioxide, can rise through old workings and shafts. The marl holes dug for brickmaking were often filled with waste, and some now give off landfill gas. Over all of it sits two centuries of made ground from foundries, chemical works and canal-side yards.

Former garages, depots and works add hydrocarbons to the picture. The ground investigation and gas risk assessment, to BS 8485, pull all of this into a protection level for each building.

The details decide it

Black Country buildings often stand on piles or ground beams to bridge poor ground and old workings, and each pile cap, beam, drainage run and service duct passes through the membrane. Every one is collared and sealed on its own. Where one sheet meets the next, the joint is welded or sealed to the specification the product carries, and we stop when the weather would prevent a sound joint.

The substrate has to be ready first. We inspect the blinding or slab and ask for sharp edges, protruding steel or loose material to be dealt with before laying.

Validation and the warranty file

Mine gas and landfill gas sites are where warranty providers most often want an independent inspector to sign the membrane off, sometimes with integrity testing as well. We can arrange either on any job, and we keep installation records for each detail so the validator and the warranty file have what they need.

Working over old workings

Sites with treated shafts or grouted workings often have ground beams, thickened slabs or capping details where the engineer has bridged a weak zone. Those change level and shape across the footprint, and each step and corner needs its own fold, patch or preformed piece. We go through the slab drawings with the site team before we start, so nothing comes as a surprise on the day.

Alongside the drainage

Most brownfield plots here also need their surface water held in a sealed tank. We install lined attenuation tanks too, so the gas membrane and the drainage lining can be done by the same crew to the same standard.