| 41 T T Hugh de Lacy Aggregates mixed to meet local roading needs Otaika Quarry is the only one in Whangarei, and it serves a large chunk of Northland, with annual production of up to 800,000 tonnes. QUARRYING INDUSTRY Winstone Aggregates “Our rock type up here is sedimentary greywacke, which is common in quarries round the country, but ours up here is softer and has a lot more fine materials in it.” Increasingly high specifications for roading aggregates is proving a challenge, but also raising the bar for the country’s quarries with their wide variation in rock quality – and Northland provides one such challenge, says Winstone Aggregates’ Otaika Quarry manager Chris Trainer. With the cost of transporting rock around the regions prohibitive, quarries like Whangarei’s Otaika are meeting rising central and local government specifications by blending their local aggregates with lime, cement and crushed concrete. Otaika Quarry is the only one in Whangarei, and it serves a large chunk of Northland, with annual production of up to 800,000 tonnes. “Our rock type up here is sedimentary greywacke, which is common in quarries round the country, but ours up here is softer and has a lot more fine materials in it. It’s not as hard as the weathered rock you find further south in Auckland,” Chris says. “So when we mix lime or cement or concrete through the rock it makes for a better-quality aggregate. The lime burns off the clays in the rock, and then we can add to the blend and bring it up to spec. “We’ve got the rock here, and we can make the resource meet the local need.” He says the specifications for a roading aggregate are largely determined by the NZTA and the local councils, with input from the Institute of Quarrying (IOQ) and roading contractors. Chris says the quarrying industry’s input is vital in the drafting of specifications that are currently being upgraded for the full length of State Highway 1, which navigates the full range of differing rock types in the country. “There are a lot of big changes coming through on the class of aggregates required for SH1, and they won’t be easy to meet in many regions because of the rock source in those areas, and that’s the challenge that we have here in Northland,” he says. “We’re hoping to get a regional specification for Northland so we don’t have to look at carting rock up from Auckland – that’s a huge distance, and the cost to the taxpayer, and the environment, would be enormous.” Chris says the IOQ has a group focusing on aggregate specifications, and is keen to help establish the parameters at the local level where the quarries are. Winstone Aggregates is the country’s biggest quarry operator, with major sites across Auckland, Waikato, Wellington and Christchurch, plus many others scattered around the country. It’s part of the NZX-listed Fletcher Building Group’s Heavy Building Materials Division, and its roots go back to 1864 when immigrant William Winstone, who was from a farming background, bought his first horse and cart and set himself up as a coal merchant and carrier in Auckland. William was later joined by his younger brother George, and in the 1870s, as W and Email: GUY@HOPPERCONSTRUCTION.CO.NZ Phone: GUY 027 479 5500 MULCHING | PILE DRIVING | RETAINING WALLS | DRILLING | STMS EARTHWORKS | DEWATERING | DRAINAGE | ROADING Building the North from One Tree Point to Auckland CONTACT P 09 430 2934 E admin@nrh.co.nz • Palm kernel • Fertiliser and metal cartage • 30 Tonne units • 6Wheelers • 5 tonne tipper • Flat deck transporter • Competitive rates • 40 Years in the transport industry G Winstone Ltd, they expanded their cartage business into the aggregates that became their mainstay after landing the contract to demolish Fort Britomart and crush and remove the rocks from which it had been built.
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