Business South April 2024

16 | Project increases draft Frank O’Boyle, South Port’s Project Director. T T from page 14 South Port NZ Ltd REGIONAL DEVELOPMENT Jim Greg 0274 334 858 0274 160 037 Site Preparation Phone 03 215 9921 jim.bates@xtra.co.nz 28 Steel Road, RD4, PO Box 5030, Invercargill Gravel Supplies Asphalt Work Driveways Excavation KBP are proud to have worked with Southport & congratulate them on their ongoing success. FAULT FINDING – LEAK REPAIR – MAINTENANCE - REDESIGN – UPGRADE Hot Water Issues – Blocked Toilets & Drains Pressure/Flow – Roof & Gutter Consent & Technical Advice 03 215 7175 | 0800 315 717 | info@kbp.net.nz | www.kbp.net.nz “There was collaboration and consultation with a wide range of stakeholders including the local Rūnanga, the Community Board, DoC, Forest & Bird, and a number of other smaller local groups that use the harbour.” The consent application took two years to come through in September of 2022, but South Port’s robust consultative process played a key part in its success. One of the key players during the investigative period was Pro Dredging and Marine, an Australian company that provides bespoke consulting and advisory work. “We had no internal dredging expertise, and Pro Dredging were our close advisors who helped us a lot during the project. We did a lot of internal research into what happened in 1980 and discovered drawings that had the location and depth of every single drill hole in the rock, as well as the size of charges that went into the holes. “Pro Dredging created a model that plotted the holes and charges and simulated what would have happened. What we discovered was that there was a good chance a lot of the material on the seabed had been fractured from the charges and was still on the sea bed awaiting dredging.” By this time the consent application had already been lodged with Environment Southland, but Frank’s research also discovered that in 1980 the Port had applied for a deeper draft than what it ended up with at that time. “So, we went back to Environment Southland and pointed that out and said that we just wanted to carry out maintenance dredging, which they granted under a Deemed Consent. We still weren’t exactly sure if drilling or blasting would be needed so the consent application was kept live.” The project entailed two types of dredging; the channel which was granite rock, and the inner harbour which was soft sediment. While Heron Construction was engaged to carry out the channel work, Dutch Dredging NZ Ltd and their vessel the ‘Albatross’ was engaged for the soft sediment work in the inner harbour. “Dutch Dredging undertakes sediment dredging for many of the ports around New Zealand and had previously completed maintenance dredging for us as well. Heron Construction had been engaged early on in the project, and helped us with some of the costings in 2017/18 when we were putting a business case together. They became involved in the dredging project at an early stage on an ECI basis.” With Deemed Consent granted, Heron Construction came in August / September 2021 to remove the granite rock that had been fractured during the 1980’s channel deepening project. While 90% of the material was able to be picked up with an excavator bucket, put on a barge and disposed of, there were some ridges that needed to be broken up, but could not be done till consent was granted. Consent was granted in September of 2022, and Dutch Dredging completed the sediment suction dredging in the inner harbour, in May and June 2023 In August 2023 Heron Construction returned to remove the remaining hard material using a ripper on the end of the excavator to break it up, removing the need for drilling and blasting that the consent had been based on. Frank acknowledges that taking on the project came with considerable risk as it was the greatest spend that South Port had ever made. “Developing the business case to support the investment was important before undertaking activity and to get the support from the Board. Between the Board, the leadership team and the staff we achieved a great outcome for the Port. We started out in 2016, thinking it could cost $200 million, and we executed it for between $12 million and $13 million. The channel deepening work in the 1980s set the Port up for forty years and while the increased draft may not provide immediate benefits, it is a benefit that will be with the Port region for decades to come.”

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