With new storms approach, work will continue Tuesday at Oroville Dam to shore up a damaged emergency spillway that prompted the evacuation of more than 100,000 residents. What are workers doing? Drops: Helicopters are dropping sacks of rocks into a hole created by erosion. Dump trucks are also bringing in more rocks to patch other spots and create slurry. Road: They’re also building a gravel road out to where the helicopters are dropping the rocks. Then the trucks can drive out and create a slurry to deposit.