AFTER the plan to reseal the faulty valve on a 4000L leaking gas tank failed, firefighters had to move to Plan B. Just 40 to 50 per cent of the flammable LPG that remained in the 4000L tank has been decanted into a truck and taken away. Now, firefighters and HAZMAT crews will remain on scene for about half-an-hour while they wait for the remaining gas vapour to disperse, Tamworth Fire and Rescue NSW Duty Commander Peter Nugent said. "It will be out of service until that valve is replaced," he said. "Once that vapour is out it will be safe to hand the site back." It's expected staff will be able to return to work at the building this afternoon or tomorrow. STAFF at the Tamworth Agricultural Institute have been evacuated as "potentially very, very dangerous" flammable gas leaks out of a 4000 litre tank. Two firefighter crews and a HAZMAT team have rushed to the scene of the leak after reports there was a fault with the safety valve, Tamworth Fire and Rescue NSW Superintendent Tom Cooper said. "It's not done what it's supposed to do, we have two crews out there plus the HAZMAT team trying to cool the tanks down until it stops venting," he said. "It's serious enough to have evacuated about 50 people." Read also: Emergency services were alerted to the serious gas leak shortly after 11am at the NSW Department of Primary Industries principal research institute on Marsden Park Road at Calala. Tamworth Fire and Rescue NSW Duty Commander Peter Nugent is on scene and said HAZMAT and fire crews are attempting to cool the faulty release valve and break up any ice that has formed. "We want to reduce any pressure and hopefully the water may break up the release valve and it should hopefully reset," he said. "Potentially this could be very, very dangerous but at the moment we have eliminated all ignition sources. "It's just a wait and see, but as a Plan B we have requested the gas company to bring over an empty tank so we can decant the contents." The 50 people who were evacuated initially moved to a nearby assembly point, but have been moved further away from the gas leak by firefighter crews. The building provides dry land research for the agricultural industries of inland northern NSW. More to come. Our journalists work hard to provide local, up-to-date news to the community. This is how you can continue to access our trusted content: