St Albans sinkhole: Filling is nearly complete

Nearly there: Over 500 cubic metres of foamed concrete have now been poured into the sinkhole in Fon

Nearly there: Over 500 cubic metres of foamed concrete have now been poured into the sinkhole in Fontmell Close, St Albans. Photo courtesy of Ringway - Credit: Photo courtesy of Ringway

The equivalent of around 6,687 bathtubs-full of foamed concrete has now been pumped into the sinkhole in St Albans, over a period of four days, and now the concrete needs to dry, according to the latest county council update.

Sky News aerial footage of the sinkhole in Fontmel Close

Sky News aerial footage of the sinkhole in Fontmel Close - Credit: Archant

Families were forced to evacuate homes when a 20-metre-wide sinkhole suddenly engulfed a chunk of road built over a historic clay pit.

Dramatic aerial footage from Sky News shows the mammoth cavity perilously close to vehicles and houses in Fontmell Close, off Seymour Road, which appeared after 1am last Thursday (1).

Residents were later alerted to the crisis when they awoke to discover they had no power, water, gas or sanitation services – with over 50 homes immediately affected.

When the road and ground caved in, the gas main was ruptured.

Emergency and utility services, along with representatives of the district and county councils and members of the Red Cross, arrived at the scene from 1.30am.

Herts county council’s resilience team asked the district council to set up a reception area for residents at Batchwood Sports Centre.

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Twenty people, were evacuated at 3.15am. But later, other residents also had to leave because of the lack of utilities, with some people fleeing to Batchwood, while others went to stay in hotels or with friends and families.

A temporary emergency access road was created for residents to get their cars out via a playing field behind the site.

Once word seeped out about the sinkhole, journalists, media vans and even a television helicopter scrambled to the incident, with St Albans hitting the headlines across the globe.

District councillor for Batchwood, Roma Mills, said: “It is an enormous hole which looks like a gateway to the underworld! It is really unnerving to think that this can happen so suddenly and so unexpectedly.

“Thank goodness no one was injured.”

Cllr Mills said that she had visited the cul-de-sac the day before the sinkhole appeared, after being told of a smaller hole in the road.

She said: “It was very deep, but it looked manageable repair-wise at that time.”

The county council has been criticised for failing to thoroughly investigate, and fix the hole when it was first reported. On Wednesday of the previous week a postman fell into it. Ironically, remedial work was scheduled to fill in the original cavity on the same morning the road collapsed.

Sally Hopkins, a spokeswoman for Royal Mail, confirmed that one of its postmen was delivering in Fontmell Close on September 23, when a drain cover gave way.

She said: “We’re happy to say that the postman was not seriously injured and we reported this incident to the council.”

While most locals speaking to this paper about the collapsing road reported hearing no noise, some said they heard a “low growl” or “low pitched crumbling sound”.

Following advice from the county council’s geotechnical experts, engineers began filling the sinkhole with a special ‘foamed’ concrete, which is lightweight and self-compacting, last Friday.

By yesterday (Wednesday) about 540 cubic metres had been pumped into it – the equivalent of four double-decker buses.

That had brought the level up to the council’s target of one metre below the road surface level. Rain has not adversely affected the filling.

Over the next week the authority will continue to monitor the level of the concrete to check for settlement and it will also carry out a geophysical survey - but just in the surrounding road and footpath - to see if there is anything unusual or irregular underground.

A spokeswoman for the district council said that electricity had now been restored via generators on the site. Also, water services have been resumed to properties and at the time of going to press, sewerage facilities were nearly fully restored.

She said, however, there was still no gas supply as the restoration of that service had to be safe before advising people they could return home.