This is the Bonus Cache for the Adventure Lab, "Marking the Ridge Route - a K9 Perspective." When working on the Adventure Lab, the coordinates will be revealed in the Journals of the two locations that are nearest this geocache.
However, there is an alternative way to claim the find without doing the Adventure Lab.
A = the last two digits of the year the benchmark was set at N34° 42.897 W118° 42.662
B - the number of brass-lined holes in the concrete structure at N34° 42.909 W118° 42.653
The final is at the latitude of the posted coordinates minus A and the longitude of the posted coordinates minus B.