12 | NZTA - Whangarei: SH1 Mangamuka Gorge T T Richard Loader Gorge repairwork making progress Mangamuka Gorge is a key connector for the Far North to Northland and to the rest of New Zealand. REGIONAL DEVELOPMENT The completion of major repairs on slip damaged roading in Mangamuka Gorge in the Far North will reconnect communities and provide an economic and social lifeline for the region, says Mark Ware, NZTA Project Director for Northland Recovery. “The State Highway 1 (SH1) corridor through Mangamuka Gorge has been closed since the storm event of August 2022. This corridor is a key connector for the Far North to Northland and to the rest of New Zealand. “It allows the community to reconnect back to health services, education, commercial and retail, whānau and friends. Journey time is really important, as well as reliability around connection, because that brings economic benefits to the region.” Mangamuka Gorge is nestled within the Maungataniwha Ranges, with SH1 running 15 kilometres through the gorge. The township of Kaitaia is a short distance away to the north, providing key health and education services along with retail to the local communities on either side of the gorge. The project is about repairing damage resulting from significant rain events over the last couple of years, enabling normal life to return to the area. In July of 2020, during a one in five-hundred-year rain event, the gorge suffered a series of road slips causing the closure of SH1 for eleven months while repairs were carried out, and the road reopened. Then in August 2022 another significant storm event three times the size of the 2020 event resulted in 15 significant slips, which again initiated closure of the road, with traffic diverted to SH10, increasing the length of the journey. “We started our geotechnical investigations to understand the extent of the damage from that point and in December 2022 we obtained $100 million from the National Land Transport Fund to commence repairs through that corridor,” says Mark. “Detailed geotechnical work, planning and design commenced in January 2023, with main contractors appointed in February, and the project really kicked off. “Unfortunately, there was another significant weather event in April 2023, where we ended up with a substantial number of additional slips, giving us a total of 35 significant slips to repair, of which 15 were deemed critical, requiring a more complex engineering solution.” T T to page 14 “It allows the community to reconnect back to health services, education, commercial and retail, whānau and friends. Journey time is really important, as well as reliability around connection, because that brings economic benefits to the region.” In addition to repairing the damage caused by the slips, and undertaking major reinforcing work, the project also involves drainage repairs and upgrades through the gorge which will help alleviate some of the risk around further slips. “At the end of the day, the water is the problem. The ground conditions are such that that it is constantly wet and more water just adds to the problem.” While NZTA is the governing body responsible for repairs to the corridor, Stellar Projects was appointed to oversee and manage the Contractor in conjunction with WSP, one of New Zealand’s leading multidisciplinary consultancy firms, who was appointed as design lead. Stellar Projects and WSP were also involved in the original August 2020 slips and have amassed significant experience in the Northland area. “Lead contractor CLL Solutions also did all the original repair work on the gorge that have held up well and were undamaged, requiring no additional work to be undertaken in these areas,’” Mark explains. “They bring a lot of experience in complex piling work, which is what we require for these repairs. This project has something like 1380 piles that need to be drilled up to 32 metres deep, with many of them 1080mm wide.” Proud to be Hiab and Transport Contractors on the Mangamuka Project � HIAB HIRE � CONTAINER SALES AND RENTAL � GENERAL CARTAGE Get a no obligation quote hello@DEHiabhaulage.co.nz dehiabhaulage.co.nz 021 777 808
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