Low-cover, heavy-duty sprinkler tank for Norlys HQ, Aalborg

For the new Norlys headquarters in Aalborg, Denmark, the project team needed an underground sprinkler water tank beneath areas with very limited build-up height. The solution had to provide a drivable surface capable of carrying heavy traffic loads while keeping excavation depth to a minimum and avoiding complex on-site works. Vertical clearance was the defining constraint, alongside stringent quality and testing requirements for fire protection systems.

ViaCon engineered, manufactured, and installed a prefabricated corrugated steel sprinkler tank optimized for ultra-low cover without compromising structural capacity. In close collaboration with main contractor and subcontractor, we delivered a DN2400 tank in Z600 galvanized steel with D3 corrugation, verified to support a 60 t traffic load with as little as 0.3 m soil cover.

Configured for reliability and fast tie-in, the tank includes two Ø250 check valves integrated in sumps, a manhole brought to surface for full inspection access, and DIN-flanged nozzles for rapid PE pipe connections at grade. Quality was assured through factory pressure testing by an independent third party in Mülheim and re-testing on site in accordance with DBI guidelines.

Installation on site took just five hours: the customer craned the unit directly from the truck into the prepared excavation and our team completed the final fit-out. The minimal build-up height reduced excavation volumes and program time, while the prefabricated approach limited site interfaces and disruption.

• Ultra-low cover, high load capacity: 60 t drivable surface with just 0.3 m soil cover.
• Fast, low-disruption delivery: Prefabricated unit installed in five hours, minimizing downtime and interface risks.
• Assured performance: Independent factory pressure testing and on-site testing per DBI guidelines.
• Simple connections and access: DIN-flanged nozzles for quick PE tie-in; manhole to grade for full inspection and maintenance.
• Optimized site logistics: Reduced excavation depth and straightforward placement limited spoil, truck movements, and on-site complexity.
• Collaborative execution: Close coordination with A. Enggaard A/S and Henning Mortensen A/S ensured a smooth, on-schedule installation.

Technical specifications

• Pipe diameter: DN2400
• Corrugation: D3
• Length: 41.3 m
• Storage volume: 187 m¬≥ (gross); 173 m¬≥ (net)
• Corrosion protection: Z600 galvanization
• Minimum cover: 0.3 m soil
• Load rating: 60 t drivable surface at minimum cover
• Valves: 2 x Ø250 check valves (integrated in sumps)
• Access: Manhole brought to surface
• Connections: DIN-flanged nozzles for PE pipe tie-in
• Pressure testing: Factory tested by independent third party (Múlheim); site-tested per DBI
• Installation time: 5 hours