Critical Infrastructure in Vulnerable Locations

Hamilton City Council is responsible for the treatment, distribution and management of Hamilton’s water supply. Raw water is drawn from the Waikato River into the water treatment plant, where it is treated to meet the Drinking Water Standards. This service benefits the community through provision of high quality water and sufficient pressure and flow to meet requirements for urban firefighting. The water supply network services more than 51,700 households and 5,500 commercial, industrial and rural premises through over one thousand kilometres of water mains and 7 storage reservoirs.

On the 2nd February 2017, through routine CCTV monitoring of the treatment plant inlet structure within the Waikato River, it was observed that a substantial section from the opposite riverbank had subsided, with approximately 500 cubic metres of material falling into the Waikato River. The slip occurred in close proximity to the eastern bulk water main, that services the eastern side of Hamilton.

The critical bulk water main was now exposed; water was seen flowing from the remains of the bank, initially believed to be from a stormwater outlet. An onsite inspection determined a failure within the bulk main valve chamber had occurred, triggering a water supply emergency to some 27,000 households.

What occurred over the following 6 weeks was of Coordinated Incident Management (CIMS), 16 hours of emergency shutdowns, extensive communication and collaboration with stakeholders, and extensive asset planning, operations and project management protocols.

The paper intends to provide an overview of emergency response techniques employed by Hamilton City Council, the methodology used to control immediate and future risk associated with the incident, issues encountered by personnel throughout the emergency response, repair, and business continuity phases, and also to share lessons learnt throughout each stage of the incident.