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Boom! Rumble! Yawn

MARYLAND JOURNAL

Regular quarry blasts in Cockeysville are hardly earth-shattering events for neighbors

October 15, 2007|By Rob Hiaasen | Rob Hiaasen,SUN REPORTER

It might sound as if the blasts are immense, but they are not. The short blasts register below the federal guidelines for such detonations; the decibel limit is 130, and Lafarge averages 116 decibels to 118 decibels per blast, officials say. At 130 decibels, a nearby home's drywall and plaster would be damaged.

A recurring rumor is that Lafarge mines in tunnels extending underneath the surrounding business district and neighborhood. But there's no underground mining anymore - the portals into the tunnels have long since been closed, quarry officials say. What people feel are the ground vibrations from an explosion of 21,000 pounds of ANFO - ammonium nitrate/diesel fuel - planted in 40-foot-deep holes inside the quarry during any given shot, LeFarge officials say. It's a dramatic show - and field trip.

Lafarge, once known as Genstar, conducts community, school and even Cub Scout tours at the spot formerly named the Harry T. Campbell Quarry. A quarry is a geological petri dish and a point of commerce and interest in a community - and possibly a great swimming hole one day.

Given the tree cover, motorists traveling Interstate 83 between Padonia and Warren roads probably don't notice the mile-long, 500-foot deep hole in the earth.

"We're shooting on the west wall today," says Lafarge plant manager Roger Cunningham, who offered a tour this month. Other days, they blast on the north, south or east walls, which accounts for why the sound is louder for some people and not others. It just depends on which quarry wall your home or business is facing that day. Also, blasts are louder in the winter because sound-muffling leaves are off the trees.

"Put your hard hat on. And yes, you'll have hat hair," says Cunningham, winding his Ford truck down into the quarry. Huge Caterpillar trucks grunt by. Quarry workers drive on the left side of the dirt road because if one of these front-end loaders ever loses its brakes, it can be steered into the high rocky shoulder and stopped.

A quarry is whittled away in layers, or "benches." About half a mile across the great pit, Cunningham points to a string of mounds along one such bench. A "blaster" has inserted explosives into 40 holes. There's not a soul in sight now. Watch those mounds, Cunningham says, and listen for the three whistles before the shot. The untrained eye doesn't have a clue where to look. But the whistles are easily heard.

"Fire in the hole," Cunningham says.

After a sequential detonation, a side of the rock mountain explodes neatly, folding back down on itself some 30,000 tons of raw material for the loading, hauling, crushing and selling. A five-second "all clear" whistle is heard, and the shot is completed. Behemoth trucks appear out of nowhere. Their work has just begun - again.

And at St. Joseph School every January, Debbie Kleim repeats the rock quarry lesson. But by then, her kids already know what's going on. In fact, when the noontime shot goes off, her children all yell "Quarry!" then go back to their art or phonics lessons. The Texas Quarry has become their quarry, too.

As for their windows, they still rattle when a shot goes off. Pictures become crooked but not everything on the church wall is rocked.

"We have that divine intervention," Kleim says. "That crucifix is not going to move."

rob.hiaasen@baltsun.com

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