The Waimea County Council in 1935 submitted to ratepayers a loan proposal of £12,000 for the bituminous surfacing of 38 miles of heavily trafficked roads.
In putting the programme into effect, the council started with the surfacing of the section of road on which the least amount of preliminary work would be necessary - the road from Richmond to Belgrove.
Due to changing methods of using bituminous binders in road paving, the council invited alternative tenders for two-coat sealing using a heavy, straight-run road oil instead of the 80/100 bitumen formerly used; and the newly-developed method of surfacing with Plant Mix.
After consideration, the council accepted the tender of British Pavements (Canterbury) Ltd., for Plant Mix surfacing and the work was soon underway.
The company set up a large plant at the Brightwater bridge and was handling from 120 to 160 yards of the prepared sealing surface per day. The installed plant and machinery consisted of two ‘kettles’ for heating the bitumen, a mixer, bins, furnaces, drying drum and crusher, costing around £8,500.
In three months, it had produced 5000 tons of mix.
Several types of bituminous paving had been tried in the district but all of them had the tendency to “bleed” during the hot summers and to become a glassy surface in the winter.
The application of small chips to cover the bleeding led to the building up of high places and a bumpy road. Engineers claimed that Plant Mix surfacing would eliminate the bleeding.
The metal being used for the work came from the riverbed of the Wairoa River near the Brightwater bridge, adjacent to where the plant was. Horse scoops took the gravel and coarse sand to the end of a tramline leading to an electric crusher.
The big stones were removed, and the remainder carried up an incline. The material was tipped onto a screen with the stones going into the crusher.
The stone and sand were then dumped by a chain elevator.
Fine sand from Monaco was mixed with the crushed metal and coarse river sand and the mixture then raised into a large revolving drying drum and heated to 250 degrees.
At that temperature it was screened again to separate the sand and stone which went into separate bins.
The correct weight of heated cut-back bitumen was then determined and the “aggregate” and bitumen, to which a measure of crude oil was added at 250 degrees, were tipped into a paddle mixer.
To ensure sufficient fillers in the mix, carefully measured fine sand was added.
The result was an even mixture which when delivered by motor lorries to the section of road being treated, was easily worked by the planing and grading machines which distributed the mix over the road to an even camber while the mixture was still warm.
Before the road was coated with the mix, it was swept with large tractor-drawn brooms to remove all the loose metal and dust which left a hard surface, and holes or depressions were filled with a mixture of stone and bitumen before the priming coat was sprayed on and covered with small stones.
For the priming coat, a quarter of a gallon of bitumen per square yard was used, while the mix was placed on the road at the rate of 3.75 tons per 100 square yards.
Ongoing council plans were to carry out the surfacing of road from the Appleby Bridge up to the Moutere Hills, and the following summer, after widening and formation work had been done, the Moutere section was to be sealed.
