NZ Ground Investigation Specification update

NZGS management committee lead: Ross Roberts

Programme: In or before October 2023

The original specification was published in 2017 for feedback. The document is now ready for an update based on this feedback. The main proposed changes are simplification of references, improving the geophysics section, and creation of a simplified schedule table for small projects.

Soil and Rock Description update

Project lead: Ross Roberts

NZGS management committee lead: Ross Roberts

Core team: Stuart ReadSusan TilsleySteve CookeDarren MaxwellVicki MoonGeoff FarquharAnn Williams, James Elvy, Nathan Schumacher, Rob Damhuis

Programme: Draft complete late 2023 for consultation

First published in 1988, and revised 17 years later in 2005, the NZGS guidelines are generally considered to be a great document. Feedback has suggested that some improvements could be made, and given that this guide is now approaching its 16th year a review has been undertaken.

Feedback was collated in 2021 through online surveys and in the NZGS Symposium through a workshop, and this feedback has formed the basis of the committee’s work. The committee comprises Ross Roberts, Vicki Moos, Nathan Schumacher, James Elvy, Darren Maxwell, Susan Tilsley, Stuart Read, Ann Williams, Geoff Farquhar, Rob Damhuis and is project managed by Amanda Blakey.

Progress and meetings have been hampered by the adverse weather events in New Zealand in January and February 2023 as group members have been involved in significant assessment and work in a number of affected regions. The committee is now getting back up to speed and has held two meetings in April and May. This follows eight meetings in 2022.

The team has identified that the updated document should focus on field description (not classification) and is developing a more clear and consistent order-of-terms to enable more efficient data entry as well as making improvements throughout to resolve the issues raised by members, while aiming to maintain alignment with best international practice wherever possible.

The committee is aiming to deliver a draft for consultation in late 2023.

Ground anchor specification

Project lead: Katy Cottingham

NZGS management committee lead:

Core team: Brabha PathmanathanGreg SaulStuart FinlanKevin AndersonKyle WebsterDavid SharpIan McPhersonJethro NeesonNima TagipouranRobert HillierKiran SaligameTony KaoTim PervanTim FarrantLars Schmidt

Programme: Draft issued for comment

The ground anchor guideline has been issued as a draft for comment. This was prepared over the last 2 years by a team of NZGS volunteer subject matter experts. The NZGS management committee would like to thank the team for their hard work and dedication in preparing this guideline. This document is intended to be used by geo/structural professionals involved in the design and construction of ground anchors and assist parties to comply with their obligations under the Building Act. The guideline has been developed using recognized international design standards, but has been specifically prepared to follow New Zealand best practice. The document is released as a draft for comment and we encourage our members to use the document over the next 6 months and provide feedback to the development team for any improvements or clarifications required. Please provide all comments by email to

NZGS will be holding a series of presentations at local branches across the country to outline what is in the guideline and how to use it for future projects. A detailed NZGS training course will also be prepared and training sessions will be run around the country.  The itinerary for the presentations and training courses will be released in the near future.

Slope stability guidelines

NZGS management committee leads: Richard Justice

Steering Group Members: Richard Justice, Eleni Gkeli, David Stewart, Ross Roberts, John Scott

Programme: Steering and Working groups meetings to be held throughout 2023 with the project aim of a deliverable report (Slope Stability Unit 1) to be published in February 2024

The New Zealand Geotechnical Society has produced six Earthquake Geotechnical Engineering Guideline Modules covering a range of geotechnical topics. These did not specifically address slope stability. 

The New Zealand Geotechnical Society have funding agreements with Toka Tú Ake EQC and MBIE for the development of Unit 1 of the proposed slope stability guidance series.  This will be an overview unit, with a similar intent to Module 1 of the Earthquake Engineering Series, and is intended to be a ‘guidance’ document, outlining what competent practice should consider and assess.  The structure of the development team comprises a Steering Group, mostly comprising current members of the NZGS committee and a Working Group, who are tasked with development of the content of the Unit.  Progress to date includes:

  • Full steering group meetings have been held five times since December 2022, and continue monthly. A combined working group and steering group meeting was in held in May 2023.
  • Working group meetings are being held every few weeks as needed.  A Report Author Breakdown has been shared for each part of the 12-section guidance document.  Each section has a lead author and generally two further authors from the working group.
  • Most of the content of the sections of the guidance has been developed and is in the process of being standardised for language and conciseness.
  • The first Stakeholders update report was provided on 1 March 2023 to EQC, MBIE and NZGS.
  • Peer reviewers have been identified and are in the early stages of their review process.

The Development team expects to have Unit 1 in a form suitable for comment from NZGS Members in September 2023.

Young Professionals Training Modules

Project lead: Miles Boub

NZGS management committee lead: Helen Hendrickson

Core team:


A gap has been identified in the training available for recent graduates. A small group is developing a series of practical training materials to help bridge the gap between university learning and professional practice.

NZ Earthworks Specification

NZGS management committee lead: Ross Roberts

During an update to NZS4431 it was identified that the lack of a consistent earthworks specification suitable for residential subdivision was causing issues with consistency and quality of work. This project aims to develop a specification compatible with the soon to be updated NZS4431.  A short form version will subsequently be developed for small, low risk earthworks projects.

This project was put on hold as group members responded to the adverse weather events in New Zealand in January and February 2023. The work is expected to re-start in the near future and an update will be issued once this has commenced.

Expansive soils practice note

NZGS management committee lead: Jen Smith

Programme:  TBC

Concerns have been raised by geotechnical practitioners in New Zealand about our approach to identifying, classifying and mitigating the effects of expansive soils. This project is intended to provide guidance for practitioners and consenting authorities to reduce the risks posed by expansive soils.  This project is intended to link in with our work on the ongoing revision of NZS 3604:2011.

Building Act section 72 guidance

NZGS management committee lead: Sally Hargraves

Core team: Nick Rogers, John Scott, Jeff Farrell, John Westerson.

Programme:  TBC

There is an inconsistent use and application of s72 of the Building Act across NZ.  Some guidance has been developed for some parts of the country, but the aim of this guidance will be to provide more clarity and consistency across New Zealand in terms of when Councils might implement s72 and under what circumstances.  This will hopefully be delivered as joint guidance with MBIE.

The guidance development team would hopefully comprise a mixture of geotechnical consultants; those with experience of the EQC Act 1991 and those with experience of implenting s72 at Territorial Authority level.  If you have an interest in this area, please contact the lead.

Subsoil drainage guidance

NZGS management committee lead: Sally Hargraves

Core team: currently in development

Programme:  TBC

There is currently no NZ specific guidance on the design, construction and maintenance of subsoil drains.  This guidance would aim to provide guidance on good (not necessarily best) practice in this area for use on land development projects, especially where filling is proposed over gullies or soft, wet ground; or where springs / seepage may be present.

The guidance development team would hopefully comprise a mixture of geotechnical consultants and contractors representatives.  Please contact the lead if you have an iterest in this area and think you may be able to contribute.

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