Hidden asset maintenance

Some hidden assets in Christchurch are maintained by Citycare Water including the Colombo Moorhouse utility underpass.

It’s a tunnel under the railway and busy metropolitan roads carrying the trunk main 450-millimetre water pipes in the city network, plus telecommunications and broadband fibre cables, electricity and a decommissioned gas line.

“It’s one of a kind in Christchurch and survived the Canterbury earthquakes without a crack,” Christchurch City Council Project Manager Peter McConnell says.

Each month the Citycare Water Pumps team undertakes a maintenance inspection in the underpass including a power reading, ensuring the lights and the sump pump are operational, and checking the pump alarm is working.

The sump pump diverts any rainwater which accumulates in the tunnel, as there’s a slight south to north slope in the terrain, Peter says.

As the tunnel is a confined space, Worksafe health and safety requirements cover manned entry.

Entering the tunnel requires a complex safety system so the team can operate underground. This includes abseiling harnesses, radio telecommunications, a spotter and a control person, and gas monitoring.

Gas readings are taken before the Citycare Water serviceperson descends to check the air is fine to breathe in the tunnel.

The underpass has withstood the elements and the earthquakes since it was built in the 1950s.

Soon the underpass will be upgraded with a new water main scheduled to replace the aged cast iron pipes in 2023 alongside the removal of the redundant gas main.