This hidden pipe likely functioned as a scour pipe from the Orongorongo pipeline.
This scour pipe is hidden within the dense bush, making it difficult to spot even up close as it resembles a fallen tree trunk from a distance. The pipe extends over a bank, allowing water to flow down into a natural gully below. Tracing the pipe back to its origin, it appears to enter the main bank above, likely connecting to the Orongorongo water pipe buried under the old section of Maintenance Road which this site refers to as Maintenance Track.
The purpose of a scour pipe is to drain water from the main pipeline to flush out debris and dirt, particularly after heavy flooding.
Near this pipe, is plumbing with gears, which was likely a valve to divert water from the main pipe into the scour pipe. Additionally, a trench crosses perpendicularly under the pipe, though its purpose is uncertain at this stage. One possible explanation is that the trench was initially dug to route the old nearby water race around a natural spur, but may have been abandoned in favour of tunnelling through the spur instead.
Special thanks to Lance Stewart for the location of the scour pipe.
