With a population of about 4,700 people, the town of Waihi is situated on the east coast of the North Island of New Zealand.The surrounding area supports horticulture and dairy farming. Waihi is an important service centre for these activities, as well as playing an increasing role in tourism.

Waihi township is within ninety minutes drive of half the population of New Zealand, including the major cities of Hamilton, Auckland, Rotorua and Tauranga. Local areas of natural beauty include the Karangahake Gorge, Waihi Beach, and the coastline north and south.

Waihi township slopes gently down from the foot of Martha Hill to the Ohinemuri River and has an altitude averaging about 90m above sea level.

The climate of Waihi is affected by its local topography. The rainfall in Waihi is relatively high, averaging in excess of 2,100 mm/year. The township lies at the northern end of an elevated basin, which is the source of the Ohinemuri River and its tributaries. The Ohinemuri River flows westwards just south of the town and then through the Karangahake Gorge to the Firth of Thames.

The Martha Project was the first major hard rock mining operation to be commissioned following the resurgence of the gold mining industry in New Zealand in the late 1970s. The Martha Mine is situated in the township, and the Processing Plant, Waste Disposal Area, and Water Treatment Plant are located two kilometres away in a rural area. Because of its location, the mining operation has received a high level of public scrutiny. This is reflected by the stringent conditions set for the project.

Mining is by open pit methods. Ore and waste rock is crushed at the Surface Facilities Area prior to transportation along a 2.7 kilometre conveyor. On arrival at the processing plant gold and silver are extracted from the ore using conventional carbon-in-pulp treatment methods.

Waste rock is used to construct an engineered earth embankment to contain the tailings. A Water Treatment Plant treats excess water prior to discharge into the Ohinemuri River.

Open pit mining at the Martha Mine is due for completion in 2006.

The Favona Underground Project

The Favona orebody lies east of Union Hill. The above-ground parts of the project will be near the existing mill that processes ore from the Martha Mine.

From 1895 for a period of about 20 years, shafts sunk at various times explored the reef system but never produced any gold. Recently, over the last few years, drilling has tested the area to a much greater depth and identified a zone of mineralisation of sufficient quantity and grade to be economic to mine.

The permitting process for the Favona Underground Project was completed in 2004 and work began on the construction of the decline at the beginning of 2005. Stope production from Favona is expected to commence in 2006. Favona is estimated to operate for about six to ten years.

Mineral Exploration in and around Waihi

Mineral exploration has been ongoing in this area since the early 1980s, although the intensity of the exploration effort has varied over this time.

Newmont’s long-term commitment to Waihi and surrounding areas means that there has been a recent increase in exploration activity. The renewed investment in the area is expected to continue for some time, depending on results.

The Extended Project

As described in the Timeline, the modern Martha Mine operation commenced in 1987. In January 1999, following the granting of the relevant consents, the Extended Project commenced. For more information see Permitting the Martha Mine.

The main features of the Extended Project are described below:

• Information gained from exploration indicated that additional ore lay within the boundaries of the Extended Project. This ore resource was estimated to be approximately 7.5 million tonnes at 3.3 grams per tonne gold and 26 grams per tonne silver; equivalent to approximately 800,000 ounces of gold and 6.4 million ounces of silver.
  
  
• The Extended Project has increased the Martha Mine's life by several years, with mine closure now expected to occur in 2006.
  
  
• The original pit, was deepened and widened. By closure the pit will have an approximate length at the surface of 850m, width of 600m and depth of around 250m.
  
  
• Adjacent to the Martha Mine site is a surface facilities area. In this area, workshops, offices, fuel bays and explosives magazines are located. The surface facilities area also houses the crushers. As part of the Extended Project, new crushers were installed.
  
  
• In order to reduce noise effects on the town, noise bunds were built in selected areas. The largest and most obvious is the Grey Street noise bund. Its function is to reduce noise, particularly from the surface facilities area. The noise bunds are grassed and planted with trees to improve visual effects.
  
  
• After excavation of the rock, the material is hauled in trucks to the crushers. Following crushing, the ore is transported to the processing plant, and the waste rock is carried to the waste disposal area, for selective placement within the Waste Rock Embankments.
  
  
• Ore and waste are transported by conveyor at different times. As part of the Extended Project, the conveyor was upgraded and widened from 1.0m to 1.35m to increase its capacity.
  
  
• Ore is delivered to the Processing Plant. As part of the Extended Project the Processing Plant was upgraded to allow an increase in ore processing, to a maximum of 1.3 million tonnes per annum.
  
  
• The Extended Project meant that additional waste rock and tailings would be produced. The waste rock to be disposed of increased from approximately 13 million BCM (bank cubic metres) to approximately 26 million BCM. Similarly, the amount of tailings increased from 10 million cubic metres to 17 million cubic metres.
  
• A second tailings storage facility (Storage 1) had already been permitted under the original 1987 consents. Investigations for the Extended Project confirmed this to be the most suitable site for the modified storage facility (Storage 1A).
  
  
• The Water Treatment Plant was upgraded to allow up to 20,000 cubic metres of water a day to be treated and discharged (subject to a number of conditions including water quality and river flow). A pipeline was constructed to a second discharge point.
  
  
• On completion of mining, the open pit area will be rehabilitated to form a lake. The adjacent surface facilities area will be developed to form a park.
  
  
• At the waste disposal area, rehabilitation of the waste rock embankments will be progressive. At closure the surfaces of the tailings storage facilities will be rehabilitated to form a combination of wetlands, ponds and grassed areas.

Above: The town of Waihi. The Martha Mine open pit is in the foreground, with the waste rock embankments and tailings storage area in the background. The coastal area behind that is Waihi Beach. The Favona Underground Project is situated to the left of the Process Plant, which can be seen behind Union Hill at the centre of the photograph. To the left (north) lies the Coromandel Peninsula, to the right (southeast) the Bay of Plenty. This photograph was taken in February 2005.