The hole was filled with cement
Residents who were forced to leave their homes when tunnelling on the Channel Tunnel Rail Link (CTRL) caused a landslip have criticised plans for work to begin again.
Three gardens collapsed and 47 residents were evacuated from their homes to a nearby church following the land collapse in Lavender Street, Stratford, east London, on 8 February.
Residents accused bosses at CTRL of ignoring their warnings about disused water wells thought to have been disturbed by the tunnelling work beneath them.
Solicitor Louise Christian said that work was due to restart on Tuesday or Wednesday, 19 metres (62 feet) from the tunnel which is thought to have caused the disruption.
The CTRL will link St Pancras in north London to Kent.
Ms Christian said the Health & Safety Executive (HSE) sent a letter to CTRL which said the authorities have not identified what went wrong.
"The residents were worried about whether there was going to be further damage to their properties and further risk to their lives," she added.
"We don't know whether the investigation works that have been done are sufficient to identify whether a further problem could occur."
She said she would be writing a letter threatening judicial review proceedings for allowing the tunnelling to recommence before what went wrong had been identified.
The original hole - measuring about 4 x 7 metres and 10 metres deep - had been filled with concrete and it was not known how it would be affected by the retunnelling, Ms Christian said.
She added that she was advising residents individually about whether they had a claim against CTRL.
Neeta Patel, whose family are still living in the Docklands after their home on top of their business, a post-office, was littered with cracks, said: "Why are they starting work when the ground is still moving?
"They haven't worked out what the problem is and they've done nothing about securing the properties."
Postponing work on the rail link has cost CTRL about £240,000-a-week.
A spokesman for the company said: "The HSE have issued a letter of non-objection so we are in a position to start work.
"CTRL is committed to put right any damage caused to residents' properties and remains in discussion with them to ensure that this happens."
The spokesman said CTRL was paying an independent surveyor to advise residents.
It had also voluntarily offered to pay up to £10,000 to cover the cost of a second legal opinion on possible claims for compensation.
The £5.2 billion Channel Tunnel rail link is set for completion in 2007.
High speed trains are set to run between the Channel Tunnel and Fawkham Junction in north Kent in the autumn.