This bridge has an interesting story, but first, about the cache. It is hidden in/on the bridge, and is in a place that is easy to reach from the bank. You will not need to walk anywhere where the footing is questionable (along the bank or underneath the bridge, for example). The cache is winter friendly. Bring your own writing utensil.
The predecessor to this bridge became unsafe several years ago, but finally a plan came together for a replacement. The massive log was harvested from the north side of Hanover, and delivered to the site very early one morning in order to avoid traffic. Have a look at this drone video of the log being transported through Hanover. Getting the log from the parking area down the trail and across the brook was another major challenge, and supposedly there is a video out there of the log being dragged, then pushed across the brook and moved into place -- all of that without removing or even damaging the many trees in the area of the crossing. Unfortunately, I have not seen that video, but I'm trying to track it down. After that, an all-volunteer team worked over the next several weeks to get the rest of the bridge built around the log, with the result what you see there today.
Congratulations to salts&marbles on the FTF!