An overturned semi-truck dumped Hazardous materials yesterday morning. According to the CHP, the accident happened just after 8:30 on Chimney Rock Road near Lake Nacimiento. Investigators say the driver out of Bakersfield was traveling at an unsafe speed when the truck and trailer left the road and overturned. Powdered limestone and diesel fuel spilled from the trailer and truck onto the roadside, creating a hazardous materials incident. Drugs or alcohol were not factors in the incident.