Locals expressed their concerns after HS2 tunnelling caused a mystery brown foam to spew out of the ground from underneath a west London rugby club.
Work on the controversial project was stopped for several hours on Saturday after dog walkers watched on in horror as the bizarre substance bubbled up at Ruislip RFC on Saturday.
HS2 workers moved to seal off the area after the hole opened up which was “most likely caused” by one of the tunnelling machines passing through a small pre-existing borehole.
Despite the slurry pool being cleared away, locals raised concerns as to what could happen when digging passes under populated areas as the £100bn project continues to bore 13 miles of tunnels towards Euston.
Local Philip Smith, 48, was walking his dogs on the grounds when he discovered the hole “bubbling away”. He filmed himself going to touch the mystery substance with his foot after his pet walked straight through it.
He told the Standard: “When I first saw it I really didn’t know what it was.
“I was taking the dogs for a walk and one of them went to look and stood in it.
“After getting up close you could see it appeared to be a foam with what looked like brick dust mixed in.
“At the centre, it was bubbling away with more coming out.”
He added: “The most concerning thing for me is that I live locally to the fields, and the tunnel path is due to go under my home.
“What if something like this were to happen or worse once it starts going underneath populated areas and people’s homes.
On going towards the pool to investigate, he said: “I was more concerned about what it was, why it was coming up and what was going to happen next?
“Was the area going to collapse?”
Chairman of Ruislip RFC, Jatin Radia, said he was watching his son play American Football nearby when his phone started “blowing up” with messages from dog walkers asking: “Oh my god! What is happening at your rugby club?”
He told the Standard: “I saw the photos and thought it was unusual to say the least.
“It looked like a bubbling sinkhole, you had a 5m pool of sludgy foam and bubbling coming through it.
“You could hear and see the bubbling.
“Obviously it raised concerns of ‘what is this stuff?’
“HS2 had already sent investigators, fair play to them, but they didn’t have a clue either. Even the specialists said something is not right but we don’t know what it is.”
“We very quickly sent the message out to all our members: ‘Do not go near it!’”
He added: “No way I was risking my limbs falling off touching that. I didn’t want to go near. Naturally my son chucked a massive log in to see if it will float.
“We’ve all watched Marvel and Dr Who and we just thought ‘will this take us into another dimension?’
“It’s one of those things you never expect to see on your own rugby ground.
“We get rabbit holes from time to time but random foam just bursting out and bubbling away - it was like an alien movie.”
“Everyone was saying it was out of Stranger Things.”
The volunteer chairman asked for greater communication from HS2 who did not warn him they were tunnelling through last weekend.
He said: “I’m not an eco-warrior or anything like that, but my concern is whether it will impact our pitches and if they are safe for boys and girls to play on.
“If you are for HS2 or against it, you would still expect them to carry out thorough risk assessments.
“The concern is that it could have happened in the middle of the game.
“That is the ultimate fear. We are hosting a Middlesex rugby festival soon where we will have more than 700 9-10 year-olds which is not a small amount of people.”
HS2 claim when the contractors saw what was happening, they sealed off the area and started extra ground monitoring with the aim of preventing subsidence resulting from the leak.
Additional ground anchors werebeing installed to protect against subsidence.
They will continue to monitor the area over the next few days.
An HS2 spokesperson said: “Upon discovering the small pool of foam in Ruislip on Saturday, HS2’s main works’ contractor SCS (Skanska Costain STRABAG) sealed off the area to investigate.
“The pool appears to have come out of an pre-existing borehole, causing foam to travel up and pool on the surface. The area is safe, the leak has been sealed, and the foam has been cleared. There has been no impact on the programme schedule.”
