The mudflow was 750 yards long, 70 yards wide and 15-20 feet deep on highway 101

The mud flow was 750 yards long, 70 yards wide and 15-20 feet deep.

This is a description and quote from: 

Hwy. 101 in Santa
Barbara County
expected to open
Monday

The San Luis Obispo Tribune

2 days ago

So, basically you have a 750 yards (or basically a 1/2 mile long lake of mud 210 feet wide filled with rocks and solid mud but also soupy mud. This is very difficult to remove because you cannot use pumps because it will clog almost all pumps made maybe except for cement grout pumps and even then branches, trees rocks and sand might clog even this type of pumps. So, you would have to resort to loaders loading soupy mud onto dump trucks and then the dump trucks (unless they were plastic lined would leak out most of it before getting to their destination. And where could they dump this but maybe into the ocean through maybe a river outlet. Because that is where it was headed anyway?

And on top of all this it was sort of a haz-mat operation because it was polluted with sewage from broken sewage lines and broken septic tanks, and chemicals from containers from sheds and garages that gardeners might use damaged by rocks, mud and trees and branches.