Rotowaro

The Rotowaro mine located 10 kilometres west of Huntly and 100 kilometres south of Auckland, is New Zealand's second largest open cut coal mine. The Rotowaro open cut mine was first worked as early as 1915 following the construction of a bridge and railway over the Waikato River. The current Rotowaro mine was opened in 1958.

The Rotowaro mine is owned by the New Zealand government's state owned mining company, Solid Energy New Zealand Limited, with the mining operations of coal extraction and overburden removal contracted out to Stevenson Mining Limited. Stevenson Mining is a private family owned New Zealand mining company. Most of the coal mined at the Rotowaro mine (70 percent) is taken by truck and conveyor to the Huntly Power Station owned by Genesis Energy and 25 percent by rail to the Glenbrook steel mill owned by New Zealand Steel, on Mankau Harbour in Auckland. Smaller quantities of Rotowaro coal is sold to North Island's home heating and industrial markets.

Rotowaro Underground Mine to Reach a Depth of 180 Metres
Mining operations are carried out at the Rotowaro open cut mine for 22 hours ( two shifts) each day over seven days a week. The mine produces between 1.9 and 1.5 million tonnes of coal a year, the exact amount depends on the demand from the Huntly Power Station. The coal is currently sourced from the Awaroa 4 open pit that commenced production in 2004. The Rotowaro mine is a deep mining operation that is expected to reach 180 metres at its deepest point. The average coal seam is between five and two metres deep with some being as deep as 20 metres.

Rotowaro Mine Overburden Used to Rehabilitate Older Workings
Coal is extracted from the Rotowaro mine coal seams using the conventional excavation and truck procedure. Once the rock and soil (overburden) that exists above the coal seam is removed the coal is then free to be mined. The overburden is taken to pits that have previously been mined and contoured to suit the surrounding countryside. It is then prepared for forestry or grazing use with the plantings of native shrubs and grasses.

Mine owner, Solid Energy New Zealand Limited, have constructed an overpass across the Rotowaro Road, a public road, to allow 48 million cubic metres of overburden to be taken from the Awaroa 4 pit to be used as backfill in the mined out Township pit. Soil is then placed over the surface of the former Township pit and planted in much the same way as the now rehabilitated Waipuna pit was a few years ago.

Solid Energy Phasing out Marketing of Rotowaro Coal to Domestic Customers
The Rotowaro mine produces a high quality sub-bituminous coal that is much sought after by lime producers, meat works, timber processors, horticulturalers and light industrial companies. A small amount of the coal is bagged and sold for home use although Solid Energy is in the process of phasing out the supplying of coal to the domestic market.