My research indicates that the aliens initially planned to use this location for their first attack. However, they ended up disregarding it due to the insufficient concussive attributes of the local features - but not quite in those words.
Make sure you use the provided waypoints / photos. The trail head is indistinct, and starts just over the roadside barrier. It will take you on any overgrown, yet quite distinct track quite close to GZ. It once was used more often by downhill mountain bike riders, but their obstacles have gradually been reclaimed by the bushland. Once you get to the turn off point, you will have a short cross country trip to the cache. Take care near GZ, there are some decent drops - but to get the cache you don't have to do anything dangerous.
On your way back, if you continue on the trail, you will come out near Lizard Rock after crossing some interesting rock ledges, and some of the most death-defying bike jumps I have seen.
Finally, make sure you take a card!