It's an hour and a half minimum drive from the CBD in a semi rural area and a 20-30 minute walk through private farmland and an airfield after q bit of 4wding. There's one or two graffiti pieces under the bridge pictured in the photo, the other side is even harder to get to.
Haven't been there but I know people who have... Bit out of the way but probably a nice thing to check out en route to Sydney. It is a fair bit of effort to get there for what it is.