According to PP, they're based in Bellvue, WA. A quick look at an online map places that about 10 mi. east of Seattle.
Being somone from the eastside of washington, everything on the westside of the Cascades is "Seattle"
Of course, westsiders think everything east of the Cascades is Wenatchee (or the Gorge).
Good to know where
PP is at though. May have to see if they do tours or allow vistors or something, for next time I'm out that way.