Thursday, 1 February 2024

In light of recent changes made by TCC regarding what they will accept for geotechnical earthquake engineering, clients may be wondering how this will affect their project.

The Bradley Seismic Model was used from 2018 for seismic assessments in Tauranga. In mid-2022 this was restricted to residential developments in accordance with NZS3604 in line with the limitations in the models report.

This has the potential to affect liquefaction, slope stability assessments and retaining wall design , if a building consent has not been issued. Based on recent experience this will also apply to subdivisions even when there is a geotechnical completion report referred to on the consent notice.

It is not possible for us to provide specific commentary on the implications for your site until the assessment has been completed as it will be dependent on the soil conditions, site geometry and what is proposed.

Therefore we recommend that if you have a project that is still have building consent applied for or issued you check the liquefaction and slope stability sections in the report you are relying on to see seismic parameters have been taken from Module 1 (2021) which are provided below for an IL2 building.

• Peak ground acceleration (amax or PGA) 0.3g

• Magnitude (M or Mw) 5.9

The BCD Geotechnical Team are happy to discuss your project and the next steps if a new or revised assessment is required.