A pair of archaeologists are calling for a major investigation after a sinkhole emerged outside a home in Plumstead, forcing 48 residents to evacuate overnight.
Firefighters cordoned off a 25m hazard zone around the 5m deep hole after it opened up on the doorstep of a newly-built home in Brickfield Cottages.
As of Friday the five households closest to the hole were still unable to return home, whilst a borehole investigation is due to take place this week.
Hexagon Housing described it as a sinkhole, but the archaeologists disagree, and instead have argued that the crater was caused by a mining collapse in the depths below Brickfield Cottages.
The hole in Brickfield Cottages, Plumstead.
Dr Per von Scheibner, an archaeologist from Forest Hill, believes there are several possible causes, including the collapse of a previously unknown mine or a fault passage in the South Metropolitan Mine used in the 18th and 19th centuries.
He told News Shopper: “The likelihood of a mining collapse is much more likely than a sinkhole but by calling it a sinkhole they give the idea it is a one-off occurrence, like there’s nothing to worry about.
“I’m afraid they’re very much oversimplifying the thing. It’s just about time that a very, very thorough investigation be done.
“I think we’re dealing with an old part of the mine which was never properly filled in in the 1950s.”
Dr Scheibner has studied subterranean structures in Greenwich for the past 30 years, alongside mining historian Dominic Clinton, 52.
Mr Clinton recently called for the closure of Rockcliffe Gardens in Plumstead – which backs onto Brickfield Cottages - after a long investigation into the Cemetery Chalk Mine below.
Since the recent incident, he has turned his attention to investigating its cause.
Dominic Clinton pictured in Rockcliffe Gardens, Plumstead.
After overlaying the survey of known parts of the Cemetery Chalk Mine on top of an image of Brickfield Cottages, Mr Clinton claimed: “The terrace of houses in which the sinkhole has appeared should never have been built.”
He has criticised the housing developer, Bromley based Skillcrown Homes for a lack of testing prior to construction and said an emergency investigation must now be done.
“Skillcrown Homes only had three boreholes drilled into chalk on the plot before construction commenced, which is ridiculous,” he said.
“It should have been 200 or more.”
The site was formerly used throughout the 20th century as a factory for soft drinks company Mackintosh’s, before it was bought by Dave Green who used it to store his vintage lorries, and sold to Hexagon Housing in 2012.
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Before construction began the developer Skillcrown was well aware of the potential problems of underground chalk mines.
In a newsletter published by Skillcrown Homes in June 2014, the company said there were two problems to overcome with Brickfield Cottages, writing: “The first was that the site had long since been subject to rumours of having disused chalk mines directly underneath and the second was than an able contractor was needed.”
They said no chalk mines or voids had been found after “extensive ground surveys”.
In response to the concerns about underground chalkmines, a spokesman told News Shopper: “Skillcrown Homes is satisfied that all the necessary and appropriate technical assessments and due diligence was undertaken.”
And when asked Hexagon Housing had nothing further to add.
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