Southland District Council

CON 23-106 - Arthur Street stormwater and wastewater upgrade

A large rain event occurred in Southland on 20-21 September 2023. This led to surface flooding across the region. Southland District Council (SDC) received complaints of surface flooding from several residents in Winton township. Two of the flooded properties were in the Mary Street, Durham Street area.

WSP have previously undertaken a stormwater model build for the township of Winton with several recommended upgrades and locations to investigate further.

SDC propose to upgrade the stormwater main on Arthur Street in order to reduce the flooding experienced in this area in future events. The upgrade would be from the outlet drain on the western side of town to Park Street. This would reduce the existing catchment upstream by intercepting the flow from Durham Street and directing it west.

SDC has funding for this work in the 2023/24 FY which will also fall into the 2024/25 FY. In order to improve the project programme a concept design has been undertaken by WSP using LiDAR survey in order for tenderers to provide pricing. Survey is currently being undertaken on site and the detailed design will be developed during the tender period.

The increase in the stormwater pipe diameter may clash with wastewater laterals. This is expected to be confirmed during both detailed design and construction.