Ohinemuri Regional History Journal 28, September 1984
By O. J. Morgan
Looking like the ruins of an old Gothic Cathedral, and standing strong and solitary on Martha Hill, is Waihi's Pumphouse, which along with the huge cyanide tanks on Union Hill are the last remaining relics of the famous Martha Mine. At one time this mine was the largest producer of gold in the world and contributed millions of dollars of overseas funds into New Zealand's economy.
A great deal of engineering skill was needed to keep the underground workings free of water. Large quantities of water are always associated with quartz reefs, especially where the rock is laced by countless fault lines, as it was in Waihi. The man chosen for this work was Mr. W. P. Gauvain, an engineer of outstanding ability.
As the shafts were sunk further and further down below Martha Hill, following the gold reefs, the quantity of water became too much for the original small pumps to handle. Therefore a decision was made in 1901 to instal a large Cornish compound beam pump, and the existing concrete building was erected to house the steam engine to drive it. This engine used steam at 150 lbs. pressure for the high pressure cylinder, which had a diameter of 60 inches, before it was passed into the low pressure cylinder with a diameter of 110 inches. The connecting rods were directly coupled to a massive iron beam which rocked with a see-saw action. One end of this beam moved a distance of 12 feat at a speed of six strokes per minute, and was connected to the pump column made up from 24 inch square kauri beams, and extending 1300 feet down No. 5 shaft.
This type of pump had been developed by no less a person than James Watt for draining the tin mines of Cornwall and its mechanical efficiency was over 80%.
The Waihi pump had a capacity of 90,000 gallons per hour from a depth of 1500 feet. Being tepid water at a temperature of 27°C, it was for a time used in the municipal swimming baths in Kenny Street. In spite of an official analysis showing it to be uncontaminated, public opinion caused Waihi's warm mineral baths to be a short-lived luxury. However, some of the water was diverted to run down the gutters of Seddon Street, to provide a continual and efficient flushing service for the commercial area of the town, and a delight for small boys.
As the mine workings continued on down, eventually to reach 1900 feet, further pumps had to be brought into service. In 1908 Mr. Gauvain installed two 370 h.p. electrically-driven ram pumps, which were located deep in the mine. The electrical power to drive these pumps being generated on the surface by gas engines coupled to direct current generators. Huntly coal was used for manufacturing the gas, and was transported to Waihi by the newly constructed Paeroa/Waihi railway, which had been partly financed by the Waihi Mining Company, because of this need for coal and other supplies.
In 1913, Waihi electrical engineers completed the first hydro-electric station on the Waikato River, up-stream from Cambridge at Horahora. Power from this station was brought the 56 miles to Waihi on steel towers by way of Matamata, the Kaimais and the Waitawheta Valley. Much of the machinery at Waihi and Waikino was now able to be electrically driven, including large centrifugal pumps which were installed underground.
The Cornish pump with its colossal beam, cylinders and polished brass fittings, therefore became redundant, leaving only the solid concrete building to remind visitors of the skill, courage and endurance of Waihi's pioneers.
The Pumphouse and the Cyanide Tanks were inspected by the Classifications Committee of the New Zealand Historic Places Trust and have now been listed as Buildings of National importance, thus ensuring their preservation for all times.