Balclutha Quarry

ResourcesBalclutha

The operation has two main resources. The first is the Clutha River. Up to 30,000 tonnes of gravel is extracted from the river each year. This is taken from Manuka Island adjacent to the companies quarry and from Clydevale. The gravel is used as feed stock for production of sand and aggregates. With the dams further upstream this resource is expected to run out in the near future.

The main resource for the Balclutha operation is the quarry 5km upstream from the plant. This deposit is a high quality Greywacke rock. The company owns about 50 hectares of land at the quarry with over 100 years of rock supply.


Winning the resource

River gravel is extracted while the river is low in the summer months and stockpiled on the river banks. This gravel is then transported to the processing plant as required during the year.

Rock from the quarry is won by drilling and blasting up to 10,000 tonnes at a time. A 30 tonne digger is then used to load trucks which transport the rock 5km to the production plants.

When gravel is delivered to the processing plant it is stockpiled on site. It is then fed into the plant with a 23 tonne front end loader. The gravel is washed over a screen with the fine material going into a sand crew and the course material going over chip screens. Most of the gravel is made in concrete aggregates.

Rock delivered to the site is tipped into the primary crusher feeder. From here it is fed into a 42 x 30 jaw crusher. The crushed material then passes over a screen to take out lower grade base course products. Any oversize goes through a Nordberg GP 300 Cone Crusher travelling over another screen to take out roadbases. This can also feed onto a Barmac Crusher and over washing/screening plant for the manufacture of high polished stone value sealing chips. A 10 cubic metre truck is used for stockpiling and supplying a neighbouring Concrete Plant.


Quality

Balclutha is the largest supplier of quality aggregates in the South Otago area, the quarry supplied around 30 different products to suit customer needs. Blackhead Quarries have an externally audited Quality Assurance system in place to IS0 9001.2000

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Environment

Working from three sits, there is a different environmental focus at each site. Winning gravel from the river means we put heavy machinery in the river and disrupt the river bank creating some discolouration. This work is carried out in conjunction with both Fish & Game and the Otago Regional Council.

Operations are carried out in such a way as to cause minimum disruption to the river environment.

The major problem with the quarry operation is the visual aspect and the quarry is being worked to shield operations from outside the site. Vibration control from blasting and water management are also managed on site.

The processing plant is the most visual area and has the biggest potential to produce dust and dirty water. Process water is washed in a series of settling ponds before being discharged. Dust is controlled on site with water sprays and airborne dust is monitored monthly.