The supposed controlled explosion showered a residential area to the north of the site with giant boulders, peppering homes and gardens, with at least two rocks smashing through the roofs of properties.
The emergency services were quickly on the scene, shortly after 2pm, and checked all nearby homes for possible casualties.
Betty Wilson (66), of Barrwood Cottages, Stirling Road, was in her bedroom when a boulder crashed through the ceiling of her bathroom and destroyed her shower cabinet.
She said: “If I had been in the bathroom I would have been killed. I heard the glass breaking and I thought it wasn’t going to stop.”
A spokesman for the Health and Safety Executive said an inspector has visited the site and is still investigating.
For our full report on the dramatic event, see Wednesday’s Cumbernauld News and Kilsyth Chronicle.