The New Turbine Arrives

Yesterday a truck backed down our access road carrying the future of this plant: the new turbine and its draft tube are on the property.

The machine is a crossflow turbine — a design choice worth a few words, because it's the heart of the whole restoration. Waterloom is a low-head site with highly variable flow: the Souhegan can run anywhere from a quiet trickle to hundreds of cubic feet per second depending on the season. A crossflow turbine handles that variability better than almost anything else. Water passes through the runner twice, the unit stays efficient across a wide range of flows, and the design is mechanically simple and famously robust — exactly what you want in a small plant that needs to run for decades without a full-time operator standing next to it.

The old turbine, still sitting in the powerhouse where it's rested for years, will come out when we're ready for the big equipment swap. That's a crane-and-coffer-dam operation planned for the next major work season. Until then, the new unit and its draft tube are staged on site, wrapped against the New Hampshire winter.

There's something satisfying about the sequencing here: dam repaired, pond refilled, and now the new machinery waiting on the grass a hundred feet from where it will spend its working life. The pieces are physically converging.

Winter is for planning. The powerhouse itself is next — the old building is too small and too tired for the new equipment, and the design work for its replacement is underway.