Quarry Operations

HG Leach quarries

“On average, a New Zealand family of four creates demand for 32 tonnes of quarried materials a year.”

HG Leach aims to help meet that need by producing high quality aggregates efficiently, safely and responsibly.”

HG Leach & Company Limited currently owns and operates four hard rock quarries, all located within the greater Thames Valley.

  • Tirohia Quarry – volcanic Andesite rock
  • Matatoki Quarry – volcanic Andesite rock
  • Waitawheta Quarry – volcanic Andesite rock, and
  • Tahuna Quarry – sedimentary Greywacke rock

These are the key sites of a quarrying operation that supplies aggregate for New Zealand’s roads, farms, buildings, railways, airports and seaports.

The company is fortunate to be located in an area that has extensive reserves of aggregates, ensuring ongoing supply for many years to come. To ensure continuity of supply, the company keeps stockpiles of aggregate at all quarries.

Quality is key

All four HG Leach quarries produce premium aggregates with an AA weathering index – the highest possible rating.

All HG Leach premium products are tested for compliance and certified by an independent IANZ-accredited laboratory.

All HG Leach products go through internal Quality Assurance inspection and testing.

All HG Leach roading metals meet or exceed New Zealand Transport Agency specifications. All product can be produced to specification as required. 
To ensure HG Leach is able to consistently produce high quality aggregates, all staff members are trained to industry standards and are supervised by certified and competent quarry managers.

Responsible environmental management

Minimal environmental impact at all levels is a key aim of all HG Leach operations. Good environmental practice is integrated into all aspects of the company’s operations as part of sound, long-term planning. 
The company is committed to demonstrating excellence in environmental management through an environmentally responsible culture.

Minimum requirements include:

  • Compliance with, as a minimum, all legal & statutory requirements
  • Applying the principles of best practice
  • Sustainable development
 of natural resources and continuous improvement
  • Reporting on environmental performance.

Premium aggregates

The premium aggregates produced by HG Leach are used predominantly in keeping New Zealand’s roading network safe and strong.

Other grades of aggregates

Not everyone needs – or wants – top quality aggregate. Hard blue metal can be damaging to the feet of valuable dairy cows, whereas a lower grade of aggregate can be just right. HG Leach produces a wide range of alternate-grade aggregates for use in:

  • Roading
  • Forestry roading
  • Drainage metals
  • Sub-division construction

Environmental maintenance

Riprap is used extensively for riverbank and foreshore protection


  • Dairy races
  • Tanker tracks


  • Driveways
  • Backfill
  • Foundations
  • Flat rock for walls, paving, and other decorative uses.