The leak was contained to the facility -- first by plant employees, and then by firefighters who were called in to take over the task.
Two workers who were trying to cool the glass with water sustained minor injuries from steam, officials said.
The molten glass looked like lava and was hotter than 2,300 degrees, officials said.
"They called us in to help (keep) the glass that was going into the basement cool," Lapel fire Chief Gary Flowers said. "We need to keep that structure cool so the whole floor doesn't collapse."
Fire officials said the building is safe and residents of a nearby neighborhood were not in danger.
Monday's leak happened while workers were trying to fix a smaller leak from Sunday, officials said.
Workers will soon rebuild the tank, officials said.
Workers will use jackhammers to break up the glass that has formed in the basement as a result of the leak.
The plant makes glass containers. Its customers include Miller Brewing Co