Longaller waterwheel

Longaller Mill

Hydromatch Consulting Case Study 7 Site Name: Longaller Mill
System type: Zuppinger Waterwheel Power output: 12 kW
Manufacturer: HydroWatt GmbH Typical Generation: 70 MWh p.a.
Client: Mr and Mrs Beaumont Design Conditions: H = 2.00 m
Q = 1.00 m3/s
Location: Near Taunton, Somerset Commissioned: August 2010
Longaller Intake
Project description:

The current owners had been planning a hydropower scheme at this former mill for 20 years before the system was finally installed in 2010. Previous feasibility studies had considered various low head turbine options but all were unsatisfactory from both a cost and a planning perspective. Plans to sympathetically update the mill with a new waterwheel system were proposed and permission was eventually granted to remove the existing listed wheel which was well beyond repair and unsuitable to adapt for electricity generation.

A layout was designed which enables as much of the historic infrastructure as possible to be preserved by positioning the new drive and generator on the opposite side of the wheel to where the old pit wheel is positioned. This now sits on a reinforced wall between the wheel pit and relief channel alongside.

The mill and surrounding area flood on occasion due to downstream flow restrictions. It is possible that future flood levels could reach the height of the wheel axle. With this in mind, the gearbox unit has been designed with labyrinth seals which prevent water ingress if temporarily submerged.

Under the guidance of Hydromatch Consulting, the scheme owners carried the site preparation and building work themselves. The scheme is accredited for FITs.