Page 43 - 00 Volume 5 The Mine

Dredge is helping to win vast coalfield

Auckland Star, Thursday November 13, 1958
Modem-day coal miners at Lake Kimihia, near of the two large artificial ponds bordering the
Huntly, are using a powerful suction dredge to help lake. Later it will traverse the same area, taking
win two million tons of coal buried 100ft under the up a 30 foot slice of mud and clay and will then
lake. Working round the clock, six days a week, the return to lift another 24 feet of overburden.
dredge is the first to be used in the Southern "The coal below is of quite high quality," said
Hemisphere on a coalmining project. Mr G L Nanson, project engineer for the contractors,
During the next few years the dredge will Downer and Company Ltd. "The ratio of
suck up more than 4.5 million cubic yards of overburden to coal is 10 to one - about the
overburden and drain 60 acres of ponded lake economic limit."
water to let wheeled earthmovers strip the Nearby, coal is being excavated at the rate of
remaining 15,500,000 cubic yards of overburden 500 tons a day from an area that was once 100 feet
from the coal seam. under the lake. The coal lies in a 29 foot thick layer
Kimihia and coal have been linked ever since pierced by the old underground tunnels abandoned
miners began burrowing under the lake in 1886. more than 30 years ago.
The underground workings were abandoned in Elsewhere big electric shovels and
1912 after over a million tons of coal had been earthmovers capable of shifting 25 cubic meters of
won from the seam. spoil at a time, are stripping overburden from the
Today, giant machines are tackling the same coal seam. They are working a year ahead of the
coalfield -from above. Costing 160,000 pounds, the machines excavating the coal.
dredge is the most expensive excavator on the job. And at Weaver's Crossing, several miles
In spite of its ships ventilators, engine room from Kimihia, a start will be made next February
telegraph and siren, it's classified as "just another to excavate 822,000 tons of coal there. Much of
earthmover." the 2.5 million cubic yards of overburden
The dredge is at present taking a six foot covering the coal has already been stripped.
'bite' of black mud under 12 feet of water in one

Although the dredge’s
funnel and ventilators
make it appear an
ocean-going vessel, the
long pontooned
pipeline snaking across
the water gives a clue
to its work.
Each year one and a
half cubic yards of mud
is discharged through
the 18-inch pipe. The
dredge has no rudder
or propellers and
moves by using its
winches which are
attached to cables
moored on the shore.