The big-rig was traveling west on Highway 580 at about 4:30 a.m. when a front right tire blew out, causing the truck to hit highway railing just west of Portola Avenue and overturn, CHP Officer Steve Creel said.
The driver was not injured, but a portion of the big-rig's 10-ton load of bark and manure spilled out across westbound lanes, prompting most of them to be shut down while CHP and Caltrans crews scrambled to clean up the mess.
There was no evidence pointing to the involvement of another vehicle in the crash, Creel said.
All lanes were reopened by 7:45 a.m., according to the CHP.
