Blasting continues at
Construction workers prepare to fill holes with explosives at the NOvA site.
Construction crews at the future site of the NOvA detector facility have blasted through two more sections of rock since the initial detonation last week.
The civil construction project in northern Minnesota is funded in part by the American Recovery and Reinvestment Act.
You can watch a video of the first blast at Fermilab's YouTube site.
“The first blast is the most spectacular for the whole job,” said Peter “Chipper” Johnson, president and CEO of Hoover Construction, the Minnesota company handling the blasting. “After that, the rocks move laterally instead of going straight up into the air.”
Still, workers clear the area within 2,500 feet of the explosions. To detonate the first section of rock, crews drilled 25-foot holes about 3 inches in diameter into the ground and filled them with Titan 1000 SD, an explosive material.
“It’s like toothpaste, kind of ooey, gooey and sticky,” Johnson said.
Over about the next six weeks, crews will use explosives to clear a 50-foot-deep cavern measuring 65 by 370 feet in the rock. The cost of drilling, blasting and excavating will be about $950,000, Johnson said.
The construction company will use all of the rubble from the explosions in constructing the site.
They will use part of the pulverized rock to form a base for roads on the site. Another portion will serve as backfill to support the structure of the detector facility. Workers will lay a third portion onto the roof of the detector building to shield the experiment from cosmic and gamma rays.
The site is located in a safely isolated area, five miles from Voyageur National Park.
The crew had no concerns about disturbing neighbors or visitors to the park with the explosions.
“At that distance, if you had any kind of wind at all, you wouldn’t hear the blasts.” Johnson said.
-- Kathryn Grim
Watch the first blast of the NOvA site.