New Zealand’s Manukau region is the busiest police district in the country. When considering the design of their new headquarters, the New Zealand Police knew that they needed to take advantage of the proximity of the site to the Courthouse which was directly across the street.
With both facilities expected to be stressed beyond their capacity, it was decided that an underground tunnel would be built to between the Manukau Police Hub to the adjacent Manukau Courthouse to create a direct passageway. There would also be a full basement development which would house cells to hold the overflow of prisoners. Both the basement and tunnel would be extremely valuable in easing the prison transfers between the two facilities. It was determined that the tunnel would be built out of fifty precast box culverts with the most sound structural integrity in mind.
When it came time to construct the tunnel, contractors Watt & Hughes Ltd. turned to Allco Agencies Ltd for their input. They knew they wanted to construct the tunnel with precast box culverts but how to waterproof them?
Allco Agencies Ltd recommended that Kryton’s Krystol Internal Membrane (KIM) was the best waterproofing choice based on performance and pricing. Allco Agencies Ltd knew that KIM performed especially well in below-grade structures which were critical for this high-traffic tunnel. All fifty of the precast box culvert segments contained KIM, ensuring that they would be permanently protected from water ingress from the inside out. The joints between each segment would be waterproofed with external membranes.