Eric William Johnson, 76, worked for the Ben Johnson trucking company — no relation — when he was hauling a trailer of rock downhill from the quarry Monday morning.
His truck went off the road and rolled over, ejecting him from the vehicle.
Johnson was declared dead at the scene from blunt-force trauma.
The accident happened around 11:30 a.m. on the quarry access road just south of Highway 154, which is private property directly across from the Bradbury Dam road, the County Fire Department said.
The CHP is investigating why the truck drifted to the right and struck the hillside, lost control and ultimately ran off the left side of the road, where it rolled over.
Investigators are also looking into whether any mechanical issues or any medical conditions the driver had could have contributed to the crash.
The investigation likely will be done next week, according to the CHP Buellton Office.
In 2010, a big-rig truck driver leaving the quarry lost control of his brakes while going southbound – and downhill – on Highway 154 and crashed into a home near the Hope Ranch Inn, killing a family of three.
Joaquin Garcia Morales, the driver, pleaded not guilty to charges of vehicular manslaughter in that case.
Leon Leonel, 23; his wife, Lorena Guadalupe-Tellez Pacheco; and their son, Jaciel Tellez, 8, a Franklin Elementary School third-grader, were killed after Morales plowed into the family’s house at 4119 State St.
Details emerged after the crash that Morales had a history of driving citations and that the truck had brake problems even before leaving the quarry, where it picked up a load to bring the truck’s weight to 80,000 pounds.
That accident prompted county officials to discuss Highway 154 safety and possible restrictions on trucks carrying heavy or hazardous freight.