Page 76 - 00 Volume 5 The Mine
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Kimihia Lake Rehabilitation
In 1976 coal extraction from the Kimihia from the bottom of the opencast.
Opencast Coal Mine ceased, and plant and Construction of the mine buildings, coal
equipment was moved to other State Coal handling and storage facilities, road and rail access,
operations in the Huntly district. Further coal and other headworks commenced in 1977, and the
remained at the bottom of the opencast but at too area of land within the opencast needed for the
great a depth below surface to economically new mine was defined and put into use.
remove by opencast methods. Rehabilitation of the remaining area was the next
Extracting coal by opencast mining step.
involves in simple terms, the excavation of a hole In July, 1978, New Zealand State Coal
to the top of the coal, dumping the overburden as Mines retained the geological and
waste, then winning the coal. The excavation environmental consultants, Applied Geology
"moves" over the surface following the coal, as Associates, to undertake a study of the
overburden from new stripping is dumped in that abandoned opencast and the directly
portion of the opencast from which the coal has surrounding mine affected land and make
been excavated. The size of the excavation is recommendations for the rehabilitation of the
determined by the depth from the surface to the area. This report covers the consultants' work, and
coal, the steepest safe angle at which the sides of the action now underway to implement their
the excavation can be cut and benched, and
allowing for a sufficient area of exposed coal in recommendations.
the floor of the pit for its most economic History of Mining at Kimihia
extraction. Winning coal by opencast must cease
when the cost of removing the overburden exceeds Coal was first mined at Kimihia from a
the value of the coal. This situation occurred at small underground mine located near the present
Kimihia where the coal beds dip away from the railway siding. After a typically stop-go existence,
working face and the coal gets deeper. mining ceased and State Coal Mines acquired the
rights to the coal, and in the early 1940's
Plans to extract the remaining coal from the commenced removing overburden for the
Kimihia area - the so-called "East Side" reserves - development of the Kimihia Opencast.
were drawn up in succeeding years. Finally in
1972, approval was given to develop the Huntly To gain access to coal beneath the lake, a
East Mine by establishing headworks inside the stopbank was constructed across the lake, and the
old Kimihia Opencast and driving into the coal southern portions drained. The lake sediments and
