Safety restrictions eased on four Tauranga homes after landslide

Damaged property from the landslide at Welcome Bay late last month. Photo / RNZ, Calvin Samuel

By Phil Pennington of RNZ

All four homes red-stickered in Tauranga’s Welcome Bay after a deadly landslide last month have had their safety restrictions eased.

The large slip hit neighbouring homes on Welcome Bay Rd, killing two people, during the storm that hit the upper and eastern North Island.

The Western Bay of Plenty District Council said yellow stickers had replaced the red.

“Given the land had dried out since the weather event, and the ‘additional weight’ on the land reduced, council’s consultant geotechnical engineers deemed the risk of imminent slip had reduced to a point where the properties could be accessed, under certain conditions,” it said.

Three homes had a Y2 type of sticker allowing short-term access, and one had a more onerous Y1, which allowed access only to certain parts of a building.

It was up to the homeowners what to do next.

“Additional geotechnical investigations for affected properties will need to be undertaken by the homeowners in conjunction with their insurance companies, to identify a way forward to remove the hazards,” council duty controller Peter Watson said in a statement.

The council was not considering an inquiry, he said.

An independent inquiry is going ahead nearby under the Tauranga City Council into the Mount Maunganui campground landslide that killed six people, and the Government may also do an inquiry.

No detailed survey of landslide risks

The history of landslides in the Welcome Bay area included a geotech study in 1980 that said: “Recent subdivisions in Welcome Bay should be examined by a geotechnical engineer as the area contains many inferred landslides, which may be reactivated by urban development.”

It was titled “A preliminary assessment of geological factors influencing slope stability and landslipping in and around Tauranga city”.

“The site of the fatal slip was not subdivided until the 1990s, with the building having been built in the year 2000, therefore it would not have been one of the subdivisions mentioned in the report,” Watson told RNZ on Tuesday.

The council had not carried out a detailed survey or assessment of landslide risks for the parts of Welcome Bay Rd in the district, he said.

“We instead require that the stability of subdivisions on sloping ground ... is assessed and demonstrated by an accredited geotechnical engineer or geologist as part of the resource consent process.”

Urban and lifestyle development areas that were known to be susceptible to land instability from studies done in 1981 and 2009 became a focus, but the Welcome Bay Rd properties were zoned rural and not included in these studies.

The studies provided input for its district plan hazard maps, covering:

• In 1981, a Tauranga County Council study looking at Athenree, Tanners Point, Ongare Point, Ōmokoroa, Plummers Point, Te Puna West and Maketū.
• In 2009, a district council geotechnical appraisal in Minden, west of Tauranga.
• In 2024, a Bay of Plenty Regional Landslide Susceptibility Study.

For the latter, “the scale at which this assessment was completed does not allow analysis on a site-by-site or individual subdivision scale”, Watson said.

The Geotechnical Society has a list of geotech studies in the area.