Attention-grabbing little headline, isn’t it?
A planned explosion at a rock quarry adjacent to Burlington International Airport “went awry” and several vehicles, some buildings and four small airplanes were pelted with rocks the size of microwave ovens.
http://www.wcax.com/Global/story.asp?S=9067853 describes rocks as large as two feet across.
The blasting company is investigating the cause. Uh, too much ANFO in the holes, maybe? :smack: Or maybe the blaster just wanted to get his rocks…
It’d be interesting to know if the fly went in every direction, or just forwards from the face. The first would be due to insufficient stemming (explosive too close to the surface), the second either from insufficient burden or a void in the rock between the explosive column and the face. Another is drilling into a void, so too much explosive gets placed in that hole. Easily found by measuring the explosive into the hole and checking the column rise. A timing error or misfire may leave the holes behind nowhere to go but up as well.
They could of being doing a paddock shot. These have no face, you’re basically creating a hole. The centre holes are shallower, with the surrounding holes deeper and angled slightly under the center holes, with the rest of the holes at the same depth and angle. The idea is to lift the center up to create space and then the surrounding holes have somewhere to move their burdens into. If the timings are wrong or a hole misfires, rock will fly.
And of course it could of been one massive operator cock-up. Been there, done that, fixed the powerlines :smack:, got given a “commemorative” t-shirt :o
Maybe you should do an “Ask the guy who blows shit up for a living” thread.