Today the huge Victorian gasworks site on a sharp bend in the tidal Thames is a place of stinking vapours, endless black mud and rubble. Across the desolate landscape move huge yellow dumper trucks, shifting clay and earth, and workers wearing masks to protect them from toxic fumes.
The dome itself is planned for the tip of the narrow peninsula created by the bend in the river. There is very little left standing above the surface - a couple of big ventilation shafts for the Blackwall road tunnel beneath the Thames and two portable lavatory cubicles.
To enter the site you have to don overalls, Wellington boots, and mask as well as hard hat. On leaving, you have to wash polluted mud off the boots in a decontamination area. Vehicles also have to be washed down.
For decades, this was a teeming industrial site where coal was converted into town gas. Old aerial photographs show it crowded with storage tanks, yards, roads and railway lines, pipework and the other paraphernalia of industrial chemistry. Tars, sulphuric acid, ammonia as well as gas were produced there.
By the early 1960s, however, all of the chemical works had closed down, and most of the area became derelict, with a jungle of buddleia bushes smothering the surface as the nation switched to North Sea gas.
The land was cursed as far as long-term, high-value development was concerned. There were no public transport links and it was isolated by the encircling river. The presence of a motorway running through the middle was little help, for any major development would have required expensive new slip roads and a junction.
But the biggest curse of all was the widespread contamination by a variety of toxic chemicals, some carcinogenic, some capable of burning skin, and heavy metals.
So this prime site near the heart of the capital was left idle for 30 years apart from some temporary development. Not until the landowner, British Gas Properties, decided to help pay for a new tube station there, on the Jubilee line extension, did major development become possible. British Gas knew of several severe "hot spots" with particularly high concentrations and quantities of hazardous chemicals. One of these was a big underground tar tank which had been shattered by a Luftwaffe bomb.
But the chemicals left in the ground by years of spills and leakages dotted around the site have spread widely with the flow of groundwater. One type of waste, a catalyst contaminated with cyanide, was used as a foundation for roads there.
The decontamination work has involved pumping up contaminated water and separating out the noxious chemicals, and taking away hundreds of lorry loads of the most contaminated soil to landfill sites. Some of the less polluted material has gone through a filtration process.
The construction of the Jubilee line underground station has produced great mounds of excavated clay, which are being used to provide capping material for spreading over the tainted soil beneath.
Phillip Kirby, construction and environment director for British Gas Properties, said the initial land reclamation project would finish on time at the end of this month, at a cost of pounds 10.5m - leaving the 60-acre dome site ready for construction to begin. But, the total area of the site is 263 acres so there is plenty more work to be done.Reuse content