Watching a Ridge Slide in Slow Motion, a Town Braces for Disaster

https://wsdotblog.blogspot.com/2018/01/crews-monitoring-land...

> The company that runs the quarry has stopped operations and has voluntarily offered to put up evacuated residents in nearby hotels for five weeks at its own expense, though the cause of the crack has yet to be formally determined.

> If we start removing material or blasting it from the hillside, it will actually make the area more unstable, creating fissures in other areas and would likely release larger amounts of debris in an uncontrolled manner. For some perspective, we’ve spent the past several years blasting rock from the hillsides along I-90 as part of the project to stabilize rock slopes and add more lanes. When we blast, it’s in very small sections and then we excavate any loose material after the blast. Over the past five years we’ve removed a little more than one million cubic yards of material – or about 200,000 cubic yards every construction season (April through October). The Rattlesnake Ridge slide is made up of about four million cubic yards of material.

> Also, blasting an unstable hillside simply isn’t safe. In order to do a controlled blast, crews need to drill into the hillside about 20 to 40 feet to put live charges into the hole. With the hillside moving, being able to drill accurately while also not causing more instability would be incredibly challenging. Even if the holes were drilled accurately, there’s the possibility that the charges won’t go off, meaning the crews would then have to sort through millions of cubic yards of debris looking for live explosives that could go off. It’s just too dangerous of a situation to put workers in.