The government report, prepared by the state's subsidence risk evaluation and regulation manager, John Johnston, in April 2023 about a month after the initial subsidence, and obtained last week by the Herald, suggests that the sinkhole which opened on March 25 was likely the result of a collapse in an abandoned coal mine.

Mr Johnston's assessment noted "limited data" to support or refute the possibility of further subsidence along Fogo Street. Still, in evaluating similar mine subsidences in and around Newcastle, the report found "these events typically remobilised several months to years" after the initial event as the remaining pillars beneath the surface gradually took the weight of the mine's overburden.

"Analysing the potential for a continuation of an existing subsidence is challenging, and limited data is available to support or refute various scenarios that may occur," Mr Johnston noted, adding that similar examples to the Wallsend subsidence at Stockton, Newcastle, Merewether and New Lambton "continued over several years".

The most recent example of a crush event similar to Wallsend happened in 2012 and remobilised in 2014, the report noted, "where it was at least partiality stopped by emergency grouting."

The details come as the City of Newcastle continues civil repair works along Fogo Street this week after the state's Mines Subsidence office gave the council clearance to fix the roads and gutters.

The Wallsend Diggers Club, meanwhile, which auspices the bowling club that has been shuttered since the sinkhole opened last year, submitted its compensation claim to the state last week, according to a members' update posted to the club's social media.

In a statement on Friday, the council said it had begun repairs of the kerb and gutter, footpaths, driveways, fencing, and road pavement along Fogo Street, as well as removal and reinstatement of affected trees, and the installation of new stormwater drainage. "Partial road closures are required to facilitate repairs, with resident access maintained where possible. Affected residents were notified ahead of the commencement of works, which are expected to take approximately four months to complete, subject to weather," a spokesperson said.

On a rainy Saturday morning a year ago, an area estimated to be between 70 and 110 metres wide along Fogo Street sank nearly a metre as, according to the Johnston report's findings, pillars that supported the roof of the abandoned Borehole Coal Seam mine began to fail, causing a crush into an excavated void.

The subsidence sparked a multi-agency emergency response, and some 40 residents of Fogo Street were evacuated and put into emergency accommodation for three nights as engineers assessed whether the damage had reached the residential side of the street.

The Johnston report details the subsidence event over several days last year, as the trough of collapsed ground mostly beneath the bowling club's greens reached a maximum depth of 700 millimetres. It notes, however, that engineers were hampered by the limited availability and accuracy of historic plans of the mine dating back as far as 1875.

Due to the age of the records, mining practices of the day, and the successive sub-letting of the mine to a number of companies over its operational life, the report says confidence in the accuracy of whatever plans were available was low and "old workings" were either inaccurately illustrated or omitted altogether.

Over the ensuing weeks, engineers bored down into the abandoned mine to survey the cause of the sinkhole, and formulated a plan to pump a cement grouting mix into the voids to stabilise the collapse and prevent progressive failure.

The bowling club has meanwhile remained closed indefinitely, and members who have spoken with the Herald since the subsidence have expressed frustrations at the parent club's perceived lack of communication as the remedial works stretched on.

As many as 65 full-time bowlers - many of whom have been with the club for decades - have rescinded their memberships with Diggers or plan not to renew in a "mass exodus" over the issue and the club's perceived silence on the fate of the venue, two long-time members familiar with the matter told the Herald last month.

Many former bowlers have taken up new memberships with the nearby Water Board Bowling Club at New Lambton, which took in the displaced bowlers after the subsidence last year.

Others have been scattered to suburban clubs further afield at Cardiff, Hamilton North and Mayfield West, members said.

In an update posted on the closed club's social media accounts, the Diggers said it had lodged a "detailed compensation claim" with the state's Subsidence Advisory but said there was no indication of how long the process would take.

The Herald contacted the club on Friday, but its acting CEO, Mark Stanborough, was not available for comment.

At a meeting attended by more than 100 members in June, some who attended said they were left with more questions than answers as the extent and estimated cost of damages to the club remained unclear.

The Diggers' most recent annual financial report, published in May, estimated the club's value at just shy of $4 million in "property, plant and equipment," but members have been disheartened by 5 Fogo Street's apparent state of dilapidation.

In the days after the initial subsidence, the Diggers CEO John Hume described the event as "devastating" for the club's bowlers, staff and general members. At the time, he estimated the cost of repairs could run into the millions.

A letter by MPC Consulting Engineers, included in the documents obtained by the Herald, noted that a "visual inspection" of the bowling club's building in April by one of the company's senior structural engineers found there were "no structural damages" but a small number of "cosmetic defects" in the classing and render and that "the subsidence event ... was unlikely to have compromised the structural integrity of the building".

Damage instead, according to the report, was centred around the greens, which bore the brunt of the subsidence.

"We had functions booked in which we have had to cancel and it has taken out all three greens which I dare say will cost $1 million per green to fix," Mr Hume told the Herald in March last year.

Months of neglect have not been kind to the bowling club, however, and members have described the despair of watching their community venue fall into "rack and ruin".

The greens have become overgrown with weeds, and members say the venue's interior has been stripped down to the bar taps, even as members wait to hear what will become of their club.

The venue was closed so quickly during the subsidence that many bowlers could not retrieve their bowls and other belongings from their lockers. The club arranged for the members to collect their effects after the Herald reported the issue in June.

Data from the Bureau of Meteorology recorded 29 millimetres of rain over the suburb in three hours over the weekend of the subsidence as a deluge hit the Hunter.

Utilities were cut off as a precaution after emergency services arrived on the scene about 9.45am Saturday, and residents were supplied with bottled water for the weekend, before mains water supply was returned.

A former miner who worked on the Gretley Colliery, and a decades-long resident of Fogo Street, who spoke with the Herald in the days after the subsidence, said that the suburb sat atop a massive underground lake of flooded voids such that, in his mining days, he could walk underground from the Colliery at Wallsend to Blackbutt Reserve without ever needing to surface.

The Gretley Colliery was the site of a 1996 mining disaster that killed four underground workers when their mining machine broke through a wall holding back an immense amount of water that had flooded the long-abandoned Young Wallsend Colliery. A subsequent investigation found that the miners had been led into the operation by maps inaccurate by as many as 200 metres.