Starting Monday, the Arizona Department of Transportation will begin blasting rock in Ahwatukee to make room for the Loop 202 expansion.
Sirens will sound a warning five and one minute before each blast pulverizes the rock. Big drilling rigs will burrow four-inch holes down into the rock, dynamite will be dropped, and then the rock will be fractured.
"Our intent is not to blow up the mountain, it’s just to fracture the rock,” said Dustin Krugl, ADOT spokesman.
ADOT said since there are houses, utility infrastructure and people around, the blasting will be highly controlled.
But some residents are concerned.
Pat Lawlis said it's a topic that makes her furious. She's head of the "Protecting Arizona's Resources and Children" group and helped file a lawsuit to stop the freeway project from happening. Arguments in the United States Court of Appeals for the Ninth Circuit are set for next month.
But she sees dubious timing in ADOT's plan to start the blasting on Monday.
"Big bullies," she said. "And destroying as much as they can as fast as they can, trying to convince everybody it's a done deal when it isn't."
Lawlis is hoping for an injunction to stop ADOT until the court can hear the case.
"If they start blasting the foothills, that's irreparable damage," she said. "You can't put the foothills back together again."
Meantime, ADOT said local residents can expect blasting to occur roughly three times per week. Each blasting session will be only seconds in length, but require 30-minute closures for sections of Pecos Road. The blasting will last through mid-2018 with the freeway extension slated for completion in late 2019.