A trace of asbestos found under the road surface near St Albans’ sinkhole has hindered further repairs to the 33ft deep cavity, which appeared in a residential street 10 months ago.

But, with in-depth investigations finding just a miniscule amount in one location near the sinkhole - 0.002 per cent - the restoration of utility services begins today (Thursday) in earnest, marking an important step forward for the full remediation of the road in Fontmell Close, Bernards Heath.

That is good news for the four families still in temporary accommodation, and other residents who have had provisional services.

Finding the asbestos during recent surveys caused a potential headache for Herts county council, which has been leading the restoration project since the collapse occurred in the cul de sac in the early hours of October 1 last year.

However, after recent additional investigatory drilling in 11 locations around the cavity established that the trace of asbestos was isolated to just one area, its removal has been organised, in line with health and safety rules.

The reason for its presence under the road surface is unknown as is its source.

Today’s appearance of Thames Water workers has been hailed by one Fontmell Close resident, David Walker, who said: “It is pleasing that we have a start date for the restoration of utility services.”

David is also happy that companies involved in the reinstallation - Affinity Water, the National Grid, UK Power Networks, BT Openreach and Virgin Media - have signalled a shorter timeframe than originally proposed.

That is due to nearby residents allowing access to their private land.

Thames Valley hopes to have reinstated sewers within three weeks, with other utilities to restore their services straight after initial reinstatement works by Ringway, the council’s highways contractor.

David said: “We will be right by Christmas”.

Ground investigations into Fontmell and Bridle Closes found no further historical mine workings under the roads, and concluded that future catastrophic collapse of the area appeared unlikely, despite “anomalies” found in an initial survey.

The county council has determined that the simplest solution to repair the road is for a “thickened reinstatement”, to fill in the road above the concrete plug used to shore up the sinkhole immediately after its appearance.

St Albans district council’s portfolio holder for community engagement, Cllr Beric Read, said: “Households in Fontmell and Bridle Closes have endured months of disruption and uncertainty. Restoration of permanent utility services followed by repairs to the road will return this attractive area of St Albans back to normal.”

There are plans to conduct more investigative work elsewhere on the heath and on the adjacent Ariston site.