| 57 Quarry legacy still proving valuable Milburn Lime, the South Otago quarry and processing operation Roger Mahan founded to improve on farm soil performance. Kelly Deeks A year on from Roger Mahan’s passing, two enduring legacies stand as markers of his life’s work: Milburn Lime, the South Otago quarry and processing operation he founded to improve on farm soil performance, and the Roger Mahan Heritage Centre in Geraldine, officially opened recently to safeguard items of national cultural significance. Together they reflect Roger’s commitment to both productive land and preserving history. Established in 1993 after Roger secured limestone from the former Dominion lime and phosphate quarry at Milburn near Milton, the business began as Hilton Lime Co before being renamed Milburn Lime Ltd in 1995. What started as a small operation with six staff has grown into a key supplier to farmers across South Otago, West Otago, Central Otago, and Southland. Today the company produces about 100,000 tonnes of agricultural lime annually and can process more than 2000 tonnes a day during peak periods. A 15,000 tonne storage shed allows dry, processed lime to be held on site, ensuring supply through the busy spreading months. Milburn Lime administration and sales manager Jenny Geard says Roger believed strongly in practical solutions that delivered measurable gains in pasture performance. “He was always focused on results in the paddock,” Jenny says. “If farmers were investing in lime, he wanted them to see the benefit in their soils and stock.” The limestone extracted at Milburn is naturally mineral rich, containing calcium, magnesium, potassium, sodium, sulphur, zinc, copper, boron, and phosphate. The phosphate content is particularly beneficial for clover growth and nitrogen fixation. Because the lime is very dry when extracted, it does not require kiln drying, reducing processing costs and maintaining product integrity. Operations at the quarry have evolved significantly over three decades. Overburden is removed before drilling and blasting the 16 metre lime face. Each blast yields 30,000 tonnes of broken limestone, which is transported to the crushing and screening plant for processing. Machinery upgrades have played a central role in lifting efficiency. A 110 tonne excavator replaced the original 20 tonne machine, while 100 tonne dump trucks now move material from the face. A Volvo L220H wheel loader supports loading and stockpile management, allowing the site to maintain consistent throughput. RURAL SERVICES » Milburn Lime In addition to agricultural lime, the company produces knaprock for dairy lanes, lime chip for driveways and horse arenas, and aggregate products including All in One 20 for driveways and paths and All in One 8 for hexagon matting. Roger’s interests extended well beyond the quarry gate. Concerned that significant artefacts were leaving New Zealand, he established the NZ Cultural Heritage Charitable Trust in 2003. The Roger Mahan Heritage Centre now houses a substantial collection of vehicles, machinery, and memorabilia, much of it gathered over his lifetime. The 5600sqm facility in Geraldine provides a permanent home for items that reflect the country’s industrial and rural past. The Milburn site itself also carries historical importance. Fossils believed to be about 30 million years old have been uncovered there, including a large whale jaw displayed in a lookout shed • General Transport - Big or small • Livestock Cartage - Inter Island & Local • Wool Cartage • Rock, Gravel, Bark & Sawdust Suppliers • Bulk Cartage • Fertiliser Cartage &Application with Proof of Placement • Otago’s only stockist of Golden Bay Dolomite Eddystone St Kaitangata | 03 413 9735 | cranleighhaulage@gmail.com We’re proud to support Milburn Lime maintained with the Waihola Looking Forward Group. Roger passed away in February 2025, and the Milburn Lime team remains focused on maintaining standards and continuity. “He set a clear direction for the business and for the heritage work,”Jenny says. “We are proud to carry that forward.”
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