Pipe Shed

So, I'm here in Methven, looking at what's called the Pipe Shed. It's a pretty unique structure, actually a section of a massive pipe that was cast back in 1940. They converted it into a shed for storing explosives, and it's the only one of about 800 such pipes that's still visible today. It really serves as a memorial to the Rangitata Diversion Race, which was a huge deal back then – the biggest public works project of its time. Heritage New Zealand has even registered it as a Category I structure.

The Rangitata Diversion Race, or RDR, was this massive irrigation project that kicked off in 1937, led by an engineer named Thomas Beck. It was a huge undertaking for New Zealand, especially coming out of the Great Depression, as it was meant to create jobs. The main canal stretches 67 kilometers from the Rangitata River all the way to the Rakaia River. They had some issues, like when heavy rains caused a slip in 1938, so they re-routed parts of the canal and used these huge pipes as inverted syphons.

These pipes were made in 1940 at a place called The Birches, south of Mayfield, with eight of them being started each day. They came in two sizes, but the larger ones were truly enormous – 3.7 meters in internal diameter and length, with walls 250mm thick, weighing 28 tonnes each! Apparently, these were the second-largest spun reinforced concrete pipes in the world at that time, only surpassed by those used for irrigation from the Colorado River and Boston's water supply. The minister of public works, Bob Semple, was so enthusiastic he actually drove his car into the first pipe laid at Surrey Hill! All the other pipes from the project are submerged, so this really is the only one you can see.

This particular pipe was installed at the Methven work camp, which was the headquarters for the RDR. They used a pre-cast control gate as a base and wooden wedges to stop it from rolling. They added concrete ends, a wooden door, and a vent, and there's even a wooden floor inside. It's in decent shape on the outside, though the interior floor has seen better days, and the door is a replacement. It's the only thing left of that old work camp. The Ashburton District Council owns the land, and it's a bit hidden from public view, surrounded by roads and grazing land. You can access it through a gap in the bushes from Main Street or via the Garden Of Harmony. There were talks about moving it to a more visible spot, and it was actually restored in 2025, with plans to make it a feature in an extension of the Garden of Harmony, alongside a decommissioned turbine from Highbank Power Station. It’s pretty cool to see a piece of such significant engineering history.