Fiddlers Flat, a DOC managed Conservation Area at Falls Dam, St Bathans. Our home for the weekend. We could finally get away for our first off-road shakedown in the caravan. The caravan was a dream to tow even on the rugged gravel road. Nothing moved in the cupboards and it was so quick to get set up once we arrived.
Falls Dam is a rock filled dam built to supply water for irrigation, completed in 1935. A decision was made to build a gravity dam in 1931, when there was a need to engage as many unemployed men as possible. It was estimated that a concrete dam would have had a 40% labour content compared to 60% for a rock fill. The other factor was the possible future raising of the dam to provide more storage. A rock fill dam could still be raised, if required.
Excavation of the diversion tunnel was started in 1931, at the same time as the stripping of the dam area, the quarrying and placing of rock to the edge of the river was being carried out. When the river had been diverted into the tunnel, a three foot diameter reinforced concrete pipe line was concreted into a trench excavated into the old river bed.
Work then proceeded on placing the rock in the dam, building a cut off wall, and installing the concrete face on the upstream wall. A quarry was established on the east side of the dam to provide rock for the bank, aggregate for the concrete and to clear a site for the spillway.
A circular concrete spillway was constructed and a vertical shaft provided to connect it with the diversion tunnel below. The final operation consisted of sealing the upstream end of the three foot pipe under the dam.
The workers accommodation provided consisted of a 8ft by 10ft tent for two men, and a limited number of rent-free married quarters consisting of two tents joined by a porch. A cookhouse was provided, but it was not well used and so eventually shut down. There are still a few chimneys remaining at the site from the worker's huts.
Horses hauled the 2 cubic yard trucks carrying rock to be tipped on the dam, and any material under 27/2 inch was rejected. Selected stone from the tunnel and the river channel was used for the lowest section of the dam. To provide a water seal for the upstream face of the dam, concrete slabs were laid.
In 2003 Pioneer Generation completed the installation of a small hydro electric station at the dam. The generator utilises the water which is surplus to irrigation and also the discharge from the dam for irrigation schemes on the Manuherekia River. The station discharges water adjacent to the diversion tunnel outlet. The peak output of the machine is 1320 KVA, producing 9 million kWh per annum.
We explored the surrounding area and even ventured up the steep hill. Unfortunately, the track around the lake was closed so no walking to the Falls dam fishing huts on this trip. Alfie loved exploring and his first caravanning adventure.
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