Sinking street hits $100,000 in costs

‘‘There's a lot of data to be reviewed.’’

Seeping drainage, three broken stormwater pipes and the installation of a temporary road around Porirua’s ‘sinking street’ have cost ratepayers about $100,000.

The northern end of Albatross Close, in the Porirua suburb of Whitby, sank a few feet in some areas during August after movements in October and November last year.

The road has been closed since then for excavation to enable engineers to investigate the cause. But the reasons behind the ground movement remain unknown.

Excavation began late last month, meaning a temporary road had to be cut between Samwell Drive and the Endeavour Park car park so residents could access their homes.

A lack of answers regarding the sinkage, as well as delays created by the one-way system on the temporary road, have left residents feeling frustrated.

Melanie Campbell, who lives on Seagull Place, said the temporary traffic lights that controlled access to Albatross Close and her own street created long delays. Many residents were simply ignoring the signals, creating a road hazard, she said.

The council’s underground checks revealed three broken drainage pipes under Albatross Close. They had become disconnected from the system after they were either cracked or bent from the force of shifting soil.

Olivia Dovey, the council’s acting chief operating officer, said the pipes had been fixed by Wednesday, but investigations into the cause of the ground movement were ongoing.

‘‘There’s a lot of data to be reviewed and it will take a number of weeks before the full picture can be understood and an appropriate solution [is] designed and implemented.’’

The work had taken longer than expected after investigations were widened to get a better understanding of the ground conditions, she said.

As a result, the road will be closed until October 13.

‘‘We hope to be able to open the road before this date, but have built in contingency time to allow for delays to weather dependent activities, such as sealing,’’ Dovey said.

The Whitby Walkway also remains closed as a safety precaution.

While the council has yet to determine the exact cost of the works, they estimate the investigations stage will cost approximately $100,000.

This includes the temporary road costs, including fencing hire and chip sealing of about $36,000.

Contractors will reinstate the original road once the work is complete. The alternative road will be closed and kept as a back-up should it be needed in the future.