Wednesday 11th Dec, 2019

NZ quarry cuts carryback to save millions

A New Zealand quarry has the potential to save up to $4.8 million through the use of a load volume scanner (LVS) to minimise profit loss due to carryback on its overburden stripping programmes.

A New Zealand quarry has the potential to save up to $4.8 million through the use of a load volume scanner (LVS) to minimise profit loss due to carryback on its overburden stripping programmes.

Rodney Aggregates Supplies runs a quarry in Whangaripo, New Zealand and supplies greywacke products for asphalt and concrete aggregates to the North Auckland region.

The company uses a Loadscan LVS to detect carryback in its truck bins, which can influence the final payments to the contractor. It uses laser scanning combined with software to create a 3D model image of trucks to measure the exact volume of material loaded into a truck or trailer bin. Each system also includes an RFID reader for automatic identification of each vehicle and load.

Rodney Aggregates Business Manager, Daniel Le Roux, said the scanner measures a significant amount of carryback by the contractor, especially when the material was sticky and wet.

“This was often up to five cubic metres per load, which on some trucks is 20-25 per cent carryback – obviously a huge saving for us,” he said.

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Around 2500 cubic metres of overburden material is stripped each day, but it is possible that up to 20 per cent of a truck load is haul back.

This is a loss of around $3250 of material not hauled, adding up to $19,500 over a working week. As the LVS has a lifespan of around five years, it’s possible to save around $4,875,000 during that time.

“In the past we used to rely on an aerial survey to calculate volumes moved,” Le Roux said.

“This meant that during the season the payments/measures were based on load counts and the final payment was sorted at the end of the season after completing the final flyover.

“There were usually arguments over final amounts, so final payment was often agreed up to three months after completion of the works.”

Le Roux said another benefit of the system was the ability to have data in real time, which helped him make payments accurate and reliable with no arguing about volumes moved.