McIntosh Drain, Kaiapoi

The McIntosh Drain in North East Kaiapoi, a modified natural water catchment area serving 1,500 hectares of largely rural land, faced significant flood risks. Gravel deposits from previous floods had raised water levels, increasing the potential for future flooding.

The project: McIntosh Drain

The Client: Waimakariri District Council 

Challenge:
The McIntosh Drain in North East Kaiapoi, a modified natural water catchment area serving 1,500 hectares of largely rural land, faced significant flood risks. Gravel deposits from previous floods raised water levels and increased the potential for future flooding. The area was also prone to earthquake risks and impacts from climate change.

Waimakariri District Council needed a resilient and adaptable flood management solution for McIntosh Drain. Traditional below-ground pump stations were considered but found to be unsuitable due to their inflexibility, potential earthquake damage, and high costs. The Council sought a solution that could handle large water volumes, be easily relocatable, and provide long-term resilience.

Solution:
Prime Pump, in collaboration with Kirk Roberts Consulting and BBA Pumps from the Netherlands, introduced a novel, relocatable flood solution. This involved installing two high-volume, relocatable BBA BA500G diesel pumps on a simple 150mm thick concrete pad. The setup included a control shed and diesel storage, allowing for easy disconnection and relocation of the pumps as needed. The future-proof design also allowed for the addition of a third pump if required.

Execution of the McIntosh Drain project took around ten months. The pumps were capable of handling 2.5 to 3.5 cumecs of water, essential for flood events. The mobile 'pad and pump' approach provided significant cost savings and reduced the carbon footprint compared to traditional underground pump stations. The pumps could be lifted and reassembled within 12 hours, offering unmatched flexibility. Diesel pumps were chosen over electric ones due to their independence from the grid, ensuring reliability during floods or earthquakes.

Result:
The pumps were successfully commissioned in July, and the project was completed on time and within budget. Less than two weeks after commissioning, the pump station effectively handled its first heavy rainfall event, proving the solution's efficacy. The Council now has a resilient, adaptable flood management system that can be easily relocated and adjusted to meet future needs. The project also highlighted the successful collaboration between Prime Pump, BBA Pumps, and the Waimakariri District Council, ensuring long-term flood resilience for the Kaiapoi region.

*Formerly known as Prime Pump, now Prime Fluid Management