Jim,
If you look through our book, you will see that each of the 20 famous hazards are detailed with dimensions. All these dimensions came from our own measurements and/or a combination of those from the course officials/grounds keepers, etc. Forrest can chime in but if I remember correctly, the measurements for St. Enodoc's bunker came from the club.
I should add the we felt this information would be valuable for people who want to really put into perspective the size and scope of these famous hazards. We were pretty proud of this section of the book.