The cache is not at the posted coordinates.
You must complete the New Berlin Historical Park Adventure Lab to obtain coordinates to this cache. The coordinates for this Bonus cache will be given to you on the last journal page.
The Adventure Lab can be found by downloading the mobile app from Groundspeak. After completing all five stages of the New Berlin Historical Park Adventure Lab, you will be shown the coordinates for this bonus cache.
Enjoy stepping back into the history of what came before in New Berlin! If you have a problem locating any stage, look at the map to see the locations!