Beating the flood zone.

Babbage engineers have conquered a significant flood zone in their design for the New World supermarket in Papakura.

The site, on the edge of the town’s shopping precinct, had flooded previously and there were known flow paths carrying water from an “upstream” catchment that covers several blocks.

Babbage Consultants civil engineer Will Djongianto said the final resource consent for the development hinged on engineering approval of the Babbage flooding mitigation plan.

The issue was “difficult and challenging” and the solution was innovative and complex.

Babbage senior architect Wilson Pickering said that at the heart of the issue was the need to keep car park gradients and contours manageable for shoppers with their trolleys, customers with pushchairs, and the elderly.

With the supermarket sited at the highest point of the 1-hectare site between East and Wood Streets, the civil engineers came up with a solution that takes water both under and over the car park.

Will Djongianto said the engineers had to combine several solutions to achieve the right gradients, get the necessary freeboard for the supermarket and to allow the storm water to flow through the site.

“When we did our first modelling we couldn’t get the gradients within the client’s brief,” he said.

“So we came up with a solution of putting a portion of the flow underground through a 1200 millimetre-diameter pipe, and allow the remaining flow to still pass across the site.

“For the overland flow we contoured the car park to maintain the flow paths, and we put in two swales and a rain garden to take and treat the water and run-off from the site.”

In completing the design, the engineers took into account climate change, the highest probable density of nearby site development and the projected run-off from the resulting increased land coverage.

“More and more sites across Auckland are having to deal with these types of overland-flow issues,” he said.

Wilson Pickering said this project involved the full complement of Babbage services - architecture, civil engineering, environmental, geotechnical, structural, mechanical, hydraulic and electrical.

And while the approach to dealing with the storm water was innovative, so was the design for the supermarket, which opened in time for Christmas.

The design focused on providing a good shopping experience and efficient operation, while minimising the building’s long-term carbon footprint, he said.

The solutions include daylight harvesting through the use of high-level glazing to allow natural light in the retail hall, automatically dimmable LED lighting, and an energy monitoring system to optimise plant operation and allow the building owners to manage energy use and identify savings.

Passive design features include the use of more overhangs to produce shade, louvres to manage glare, and the selection of materials such as pre-cast concrete walls to improve thermal performance, 

Other features include harvesting rainwater for use in washing down the loading bay and other areas, recovering heat waste from the refrigeration and air conditioning plants to heat water and provide winter hearing for the supermarket, and CO2 refrigeration. 

“An important consideration of the architectural design was to successfully integrate the building into its environment,” Wilson said.

“This has been achieved by the strong entry point statement and varying the building form, detail and scale. Bays break up the building’s facades, and glazing, louvres and a stepped roof form were used to reduce the overall visual scale of the building.

“The client’s brief to Babbage was to provide a well-designed, modern, attractive shopping environment, and we’ve delivered.”

The Team

The Babbage team involved in the projects included:

•Architecture: Richard Elliott, Wilson Pickering, Lachezar Karadzhov, Ingo Ratsdorf

•Structural engineering: Dr Victor Lam, Ivy Lo

•Electrical engineering: Matthew Foskin, Tommy Lee, Vito Brkovic

•Mechanical and hydraulic engineering: Aslam Javed

•Civil engineering: Michael Martin, William Djongianto

•Geotechnical engineering: Malcolm Stapleton, Rob Sandquist

• Environmental engineering: Dr Nathaniel Wilson, Tim Muller

For more information: 

Wilson Pickering - 09 379 9980

Beating The Flood Zone