Advancing stormwater resilience: Another milestone achieved

The stormwater upgrade on St Vincent Street has been completed, on time and within budget.

The infrastructure upgrade, which was scheduled for seven months, began in April 2023 with a budget of $3.2 million and required a full road closure.

Nelson Mayor Nick Smith says the upgrade of these stormwater pipes in lower St Vincent Street is about making our city more resilient to flooding and climate change. 

“It is difficult to appreciate the scale of these engineering works when they’re underground, but they involved the installation of a massive pipe, 1.8 metres in diameter, and a large stormwater mixing chamber.

“It has been disruptive for the central city, but this is work we needed to do. It is a credit to the Council engineering team and contractors that this $3.2m project has been delivered on time and within budget. 

“This lower St Vincent Street project sits alongside the $27m investment at Saxton and the nearly $10m in Rutherford Street and illustrates the importance Council is giving to ensuring our infrastructure is up to standard and to improve the resilience of the network.” 

Group Infrastructure Manager Alec Louverdis says Council’s preference is to undertake ongoing infrastructure projects without the need to put a full road closure in place, but in this case this was the best option.

"We explored alternatives to a road closure; however, these alternatives proved to be expensive and would have resulted in an extended project timeline, causing additional inconvenience to businesses and residents. We’d like to thank everyone for their patience as this important work was carried out.”  

As well as upgrading stormwater pipes, a crucial component of this project involved constructing the stormwater mixing chamber that allows stormwater from various catchment areas to blend in a manner that reduces the potential risk of flooding during substantial storm events.

“Before we could build the chamber, we needed to excavate, which required us to drive large steel beams into the ground. This process alone took contractors 10 days. The walls of the chamber are 15 tonnes each and they needed to be placed before we could pour the floor slab and place the 18t ceiling panels.” says Louverdis.

Adding to the complexity of this project was the need to relocate existing services such as wastewater pipes, water reticulation pipes, stormwater pipes, fibre-optic telecommunication cables, and electrical cables 

Contractors had previously upgraded the stormwater pipes along Hastings Street, which feed into the new mixing chamber on St Vincent Street.