This cache may only be found when a cacher has participated in the Adventure Lab: Historic Buildings of the Sequim-Dungeness Valley. And, that the person must have completed all five of the waypoints. Each location will provide a clue to the final.
Thank you to Mr. Grant, Mrs. McInnes, and Tolmaus for helping with the information provided for the Lab Cache locations.
Congratulations to Hwy88 for completing the Adventure Lab series and this Bonus Cache first. 