| 45 Richard Loader Flood protection upgrade for Saxton The upgrade to construct a new open and covered culvert system will enable the area to withstand a one-in-100 year flood event. Tasman: Nelson City Council - Saxton Creek Upgrade REGIONAL DEVELOPMENT Design solutions • Concrete placing services • Pathways & patios - Driveways - Creative concrete - 0211776110 info@concretemax.co.nz www.concretemax.co.nz www.isaacandersenart.co.nz Extreme weather events in December 2011 and April 2013 caused significant flooding to both commercial and residential properties in the Saxton area of Nelson, well known for the Saxton Field Sports complex near Stoke. In response, Nelson City Council initiated a project in 2015 to improve the flood protection in and around Saxton Creek. The first three stages of the project have been completed with the fourth stage to upgrade Saxton Creek from Main Road Stoke to the sea now underway. Currently, this segment of the creek is severely under-capacity, with an open and partially covered culvert with a capacity of less than a one-in-five year flood event. The upgrade to construct a new open and covered culvert system will enable the area to withstand a one-in-100 year flood event. Tracy Filipo, who is project managing the stage four upgrade on behalf of the Nelson City Council, says the scope of the project work is huge in terms of complexity, financially and constructability, but without it, the benefits of the previous stages cannot be realised. “The culvert area is being widened to at least double what it was previously, and runs 230 metres underneath Main Road Stoke, to Whakatu Drive and then out to the sea.” The project, costed at more than $24 million, is being co-funded by the Nelson City Council, with $7.5m funding from Kānoa - Regional Economic Development & Investment Unit. This is one of several Resilient River Communities projects being delivered that has benefited from Kānoa – RDU investment. These projects support the development and upgrading of vital river management and flood protection schemes across the country, with the programme supported by a total investment of over $200 million. Downer Construction were awarded the project. An ECI process was used to develop the methodology, with work commencing in October 2021. Part of the work involves removing the existing culvert, driving sheet piles into the ground to widen the area, and positioning massive pre-cast concrete panels into the widened area, grouting the adjoining panels together. Large diversion pipes, capable of being moved side to side to enable a wider working space, are also lowered into place, to allow fish passage and waterflow while project work is underway. “There is also a very large ecology element, which includes fish, eels and inanga,” explains Tracy. “We cannot impact the ecological environment and the diversion pipes have fish passages enabling them to go down and upstream.” While the diversion pipes keep the water at bay, Tracy says the ground conditions are not particularly good quality as the site is coastal and pumps have been installed to keep everything dry while the work is progressing. Other project challenges include tidal conditions occurring twice daily, the project work occurring between two major roads, a rich cultural and ecological area and limited room to work between two large industrial sites. Tracy say ECI (early contractor involvement) has played a large part in the success of the project to date, with a real partnership relationship between the Council and Downer Construction. “We cannot impact the ecological environment and the diversion pipes have fish passages enabling them to go down and upstream.”
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