Land Instability

What is land instability?

Land instability refers to land which has the potential to slip when saturated with water. Generally, it is steep slopes and cliffs prone to slipping.

Where are the land stability areas identified?

The District Plan maps identify land stability areas in Athenree, Tanners Point, Ongare Point, Ōmokoroa, Plummers Point, the Minden (Lifestyle Zone), Te Puna West and Maketu.

You can view these maps below.

Search your property - current natural hazard maps

To show the natural hazard map for your property please enter a valid Address or Parcel ID below and click the launch button. Or you can browse the natural hazard maps.

Tips for finding your property:

Type the address in full such as 10 Example Road or 10 Example Street, instead of using street name abbreviations (Rd or St etc)
If there are identical addresses in other parts of the District, you'll need to type in community abbreviations e.g. Beach Road (KK), Beach Road (MAK) or Beach Road (WB). Help with identical addresses
If searching by Parcel ID, recent letters from us bout natural hazards show your Parcel ID number.

How has the mapping been done?

To generate the land stability maps we take into account the following things:

Steepness of slopes
Height of cliffs
Presence of weak or sensitive soil or rock
Stormwater runoff
Groundwater levels

For the Minden Lifestyle Zone, there are five different classifications of land instability:

Minden A - land subject to or likely to be subject to instability
Minden B1 - land potentially subject to instability
Minden B2 - land potentially subject to instability (to a lesser degree)
Minden C - land unlikely to be subject to instability
Minden U - land not included in the original zone boundary but potentially subject to instability

For the other areas, there are two different classifications of land instability:

Land Stability General - vulnerable to long term landslip risk
Land Stability Landslip - possibly subject to instability

Technical Reports

Here is the technical report supporting the Minden land stability areas on the District Plan maps:

Minden Lifestyle Zone

BECA Initial Assessment Minden Rural 3 Zone Structure Plan Geotechnical 2009 (PDF 3MB)

Here is the technical report supporting the other land stability areas on the District Plan Maps:

Athenree, Tanners Point, Ongare Point, Ōmokoroa, Te Puna West and Maketu

Tonkin and Taylor Stability Assessment of Coastal Land in Tauranga County 1981 (PDF 4MB)

What further work is coming up?

Council and the Regional Council are currently identifying land susceptible to landslide (from earthquake and intense rainfall) across the District.

Frequently asked questions about land stability

What are the requirements if I am constructing a habitable building or shed/garage?

You will need resource consent. You will need to provide a geotechnical report for the land you want to build on. This will determine whether the land is suitable for building on and what foundations will be required. There is an exception however for building on land within the Minden C. While building consent would still be required, there is no specific requirement to get resource consent or provide a geotechnical report because we know the land is unlikely to be subject to instability.

What about minor structures?

You will need resource consent for anything else that is defined as a structure in the District Plan e.g. carports and some decks, pools and tanks. A geotechnical report will also be required. There is again an exception for building on land within the Minden C as explained above. Minor structures may also require building consent.

What if I want to do earthworks?

You will need to get resource consent for any earthworks. A geotechnical report will be required to ensure that the earthworks will not worsen any existing land instability. Also check with the Regional Council as it also has rules for earthworks.

If I have a building site approved from a previous subdivision can I go ahead and build?

Yes, but only if the subdivision has addressed all identified natural hazards, and the building works are in accordance with the requirements of the subdivision. If new natural hazard information has become available since the subdivision, this will need to be addressed when you go to build.

Will I be prevented from doing any new subdivision?

Being within a land stability area is unlikely to stop you from subdividing if you would otherwise qualify. However, you'll need to provide a geotechnical report with the resource consent. This will help identify suitable building sites and will explain what foundations are required. If there are no suitable building sites, a subdivision can be declined.

Where can I find the District Plan rules for land stability areas?

Within Section 8 - Natural Hazards.

Who can I ask to prepare a geotechnical report?

Here is a list of approved geotechnical engineers.

What is Council doing about the Ōmokoroa Slips?

For questions about the Ōmokoroa slips, please contact Peter Clark at peter.clark@westernbay.govt.nz.

Got a different question?

If you have any further questions, please contact Council on 0800 926 732 or at customerservice@westernbay.govt.nz.