I found this location while looking for a hiding spot for a new puzzle. Nearly thirty years living in the area I had no idea this was here, so I thought I would share.
At the posted coordinates you will find a brass plaque of significance to the location. The plaque has a year the digits represent ABCD. The cache is found at;
N 33° 39.ABD W 117° 39.(ABC x 2) + 64
Digit sum of the unknowns is 29.