This tunnel was once used to store chemical weapons. It could become a bike path

During World War II, a tunnel in Glenbrook at the base of the Blue Mountains was used to store thousands of tonnes of mustard gas. Those contents – and the men who were responsible for looking after the deadly chemical weapons – were such a secret that locals living nearby did not know of them for at least another 50 years.

Today, the Lapstone Hill Tunnel remains closed and unused, its facade sporting graffiti and years of erosion. But Blue Mountains City Council has a plan: convert the 130-year-old disused railway tunnel into a pedestrian and cycle link.

“This is an Australian historic gem that has been locked away from the community for over a century,” said Blue Mountains mayor Mark Greenhill. “It is about time it was reopened and used for rail enthusiasts, walkers and cyclists alike.

“It has massive potential as a tourist attraction site to generate wealth and income for our local economy.”

After the lethal gas was removed, Lapstone Hill Tunnel, also known as Glenbrook Tunnel, returned to what it had been before: a mushroom farm. But the tunnel’s troubles didn’t end with the war – in 2016, the then-owner of the farm was evicted due to evidence of unsafe workplace practices and environmental contamination, the Blue Mountains Gazette reported. For the past 10 years, the tunnel has been closed to the public.

Since 2023, however, the council has slowly been working towards its vision of reopening the tunnel, but Greenhill said the extent of damage and cost of remediation meant that $4 million in funding that was previously received from the state government had been insufficient to reopen it safely to the public.

The council said it has already remediated 1700 tonnes of rubbish such as mushroom farm compost material and removed 1200 tonnes of sediment from in and around the 660-metre brick-lined tunnel.

The State Heritage-listed tunnel is managed by Crown Lands NSW, and the council entered into a licence agreement with it to commence remediation works. Blue Mountains City Council is now calling on the state government to provide additional funding to complete the remaining precinct works.

“We’ve cleaned it up. We’ve decontaminated it. It’s ready for community use, but that funding goes to waste if we don’t get the extra funding to make it safe for people to access and egress, for people to park and use it safely,” Greenhill said.

Minister for Lands and Property Steve Kamper declined to respond to questions on additional funding for the activation of Lapstone Hill Tunnel.

The Sydney Morning Herald has a bureau in the heart of Parramatta. Email [email protected] with news tips.