The employee was doing routine snow clearing along SR-410 when the avalanche occurred around 10 a.m.
"The slide came over me -- it was a pretty good rumble," said Tom Martinson. "I thought about my wife... that she would be worried."
Another employee nearby radioed for help.
Crews arrived to find the trapped employee was not hurt and still had good ventilation, so they executed a slow and safe rescue, finally freeing the man five hours later.
"A quicker rescue was possible, but only with an increased risk," said Wayne Frudd, WSDOT safety manager. "Cool heads, communication, good training and the right equipment were important to this rescue operation."
Since April 2, crews have been busy plowing and blasting their way through heavy snow in order to reopen Chinook Pass to traffic by Memorial Day weekend. However, this week the pass received more than a foot of snow and warmer temperatures increased avalanche danger, WSDOT officials said.
Crews are still aiming to reopen the pass by the holiday if conditions improve.