Robert Maust, 14, was released from the hospital Thursday, less than two days after the accident, and was expected to make a full recovery.
Maust told reporters at a news conference at Children's Hospital of Pittsburgh that he was sitting on the upright slab, used as a retaining wall along a roadway, and jumped from it across the ditch to retrieve a ball. Then, he heard a "crack sound."
The slab pushed him across the ditch, pinning him against the bank. It took rescuers two hours to free him from the six-foot-by-three-foot slab.
"I spent two minutes trying to move just so I could breathe," he said. After he was able to breathe, "I was a little worried. I didn't say anything. Then I said the Act of Contrition and prayed to God."
Maust described the paid as "the worst pain in my life. ... I was in pain for the whole two hours."
A three-inch tree root and a rock helped prevent all 3,800 pounds of the concrete block from bearing down entirely on him. Had it not been for the rock and root, he said, "I wouldn't be here. I prayed to God and asked for a miracle and I just hoped for the best."
Rescuers inflated air bags under the slab to relieve pressure until they could lift it with a harnesses.
His parents waited anxiously.
"Usually they freak out like in hockey accidents and stuff, but I was surprised ... they weren't flipping out. They were just being supportive," Maust said.
When he was freed, his mother, Stephanie Maust, said, "He took my hand and kissed it and said, 'I love you.' And that was probably the greatest moment that we've shared since the day he was born."
The slab did not look precarious, he said. "Everything, to me, looked sturdy. But, you know, 3,800 pounds looks sturdy anywhere."
Maust was treated for cuts and bruises but did not break any bones. He said Thursday that he was still feeling the effects of the accident.
"I'm still stressed and (have) tight muscles and stuff," he said.
Dr. Edward Barksdale Jr. said Maust probably avoided more serious injury because of his youth and positive attitude.
Maust even wanted to play hockey this weekend, but doctors did not clear him. He's not sure when he'll be able to resume hockey, but he could return to school next week.
Stephanie Maust said she hopes whoever is responsible for the ditch will take measures to shore it up and make it safe.
Scot Fodi, Middlesex Township's manager, said the township installed the retaining wall two years ago after being alerted to erosion along the roadway adjacent to the ditch.
About a year ago, the Saxonburg Area Authority installed a sewer line between the retaining wall and roadway, said Paul Cornetti, engineer of the Saxonburg Area Authority.
Both agencies said they were investigating.
"We're looking at all aspects of what happened. We're not speculating on any aspect of the fall," Fodi said.