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The mine produces sub-bituminous coal. The current mine, sometimes referred to as the Kopako 3 Opencast mine, is located approximately two kilometres to the south east of the now flooded Kopako 1 & 2 open cut pits.
In a 2008 submission Glencoal stated that it had been mining coal in the Waikato region since 1919 to provide a secure long-term energy supply for dairy factories in the region. It had been a significant coal producer in the Maramarua Coalfield since 1946, when Glencoal purchased the United Coal Company (UCC)and developed the Kopako opencast mine to supply its parent companies’ dairy factories. In 1958 Glencoal joined with the New Zealand government (later Coalcorp, then Solid Energy) to develop the Kopako 1 & 2 open cut pits to supply the Meremere power station, which was decommissioned in 1991.
Glencoal mined the number 2 opencast until 1996 and then developed the no 3 opencast with the coal transported back to the coal processing plant at Coalfields Road. Coal from the mine is used in the boilers at Fonterra's Waitoa, Hautapu and Te Awamutu milk processing plants. The coal-fired boilers generate high pressure steam for electricity and low pressure steam to evaporate water from concentrated milk for milk powder production. In 2008 Glencoal stated that the Waitoa and Te Awamutu plants each used 55,000 tonnes while the Hautapu plant used 10,000 tonnes.
In 2008 Glencoal stated that at the current rate of extraction, the Kopako 3 Opencast mine would be depleted by approximately 2017. As part of its long term plans, Glencoal intended to utilise its coal reserves in the Maxwell block as part of the eastward development of the Kopuki sector of the Maramarua Coalfield. Extraction of the coal in the Maxwell Block would need to be mined at the same time as the adjacent Stirling Block. Glencoal stated that these blocks were part of the last remaining significant blocks of low cost, low sulphur opencast coal available in the Waikato, and could yield approximately 1,666,700 tonnes.
In September 2012 Fonterra announced that Glencoal would be applying for resource consents to develop an open cast coal mine on 30 ha of farmland that it owns near Maramarua in north Waikato. The proposed mine would replace the 18 year-old Kopako 3 mine. 
Location: Kopuku, about 70 kilometres south of Auckland
Type of coal: sub-bituminous
Main markets: Solely supplies Fonterra milk processing plants
Articles and Resources
- New Zealand Petroleum and Minerals, "Operating coal mines", Ministry of Economic Development, accessed October 2012.
- "Meremere makeover",Contractor, Volume 31 No.1, February 2007
- "Statement of Evidence for Benjamin William Coleman for Glencoal Energy Limited, Margaret Stirling, Jan Stirling and Andrew Stirling", February 26, 2008.
- "Coal costs force Fonterra's hand", accessed October 2012
- Ministry of Economic Development, "Operating coal mines", Ministry of Economic Development website, accessed March 2012.