Forgotten Traditional Cache

Today I was browsing the Geocache Map, a ready, snaplock container in hand, looking for a suitable spot close to home. Behind Brookdale Terrace, an unoccupied patch of bush sat, seemingly available, and that afternoon I headed down looking for a decent hiding place. In the 80's a flood swept through this gully, and caused a three-car pileup on the Great Western Highway. The area has been notorious for floods, but maintenance has ensured issues no longer occur. This area is somewhat forgotten and this is where the name comes from.
There's a split between two houses along the street, with a wide path opening allowing for access to GZ. Don't be discouraged by the fact that an opening isn't shown on Google Maps - switch it to satellite and you'll see it. Once down, a mild bush-bash downhill will bring you to a gully-like formation, with a large metal pipe extending from one side to the other (I'll let the hint say the rest). The cache is hidden very well and it'd be appreciated upon finding it to rehide it just as well. I'd advise against trying this when wet, unless you're extremely confident (or willing to squelch around for a bit).