NZGS Earthworks & Ground Investigation Specifications

Two committees have been working hard for the past six months on updates to the NZ Ground Investigation Specification, and on the creation of a brand new NZ Earthworks Specification. These documents are now ready in draft format for member feedback. Consultation will close in late November, and it is our intent that these documents will be finalised in early 2023 once your feedback has been addressed.

Please provide your feedback on this form:

A clear and effective specification is an essential tool to help ensure that projects achieve the objectives desired by the client, geotechnical designer and contractor. While project‐specific specifications can be useful in accurately describing the exact requirements for each project, they result in a steep learning curve for contractors on each project where a new specification is
encountered, risking errors, rework, and increasing costs.

These specifications have been developed to cover geotechnical aspects of common civil engineering projects to:

  • Improve efficiency by reducing the need to create new specifications for every project.
  • Reduce risk from mistakes by introducing consistent expectations across projects.
  • Set standards for geotechnical works at a level that reduces project risk to acceptable levels by specifying good practice.

These specifications may be used as stand‐alone documents for purely geotechnical projects, or integrated into a larger specification for projects with other elements.

It is strongly recommended that you read NZGS_000 (user guide) which explains how the various documents fit together.

Ground Investigation Specification

The NZ Ground Investigation Specification was first published in 2017. Intended to improve consistency in ground investigations while making the procurement process more efficient, it has been widely adopted. It was always the intent to update the document after a few years to reflect new techniques and to fix any issues that have been identified. A first tranche of changes have already been put into the updated draft document, and the format has been changed to align with the new suite of NZGS documents. We welcome feedback on these proposed changes, as well as any other aspects of the document which may need improvement.

Key changes made are:

  • The geophysics sections have been reviewed and updated to reflect current practice
  • A shorter Bill of Quantities has been made available which is easier to use and well suited to smaller projects (the existing NZ Earthworks Specification Volume 3 has been split into 3a and 3b, which are for large and small projects respectively)

Earthworks Specification

The NZGS committee who worked on the new standard NZS4431 has continued their work to develop an earthworks specification that is intended to be entirely compatible with, and enable the implementation of, NZS4431. The document we have prepared and is now being consulted on is the “long-form” specification described in the introduction to NZS4431.

This specification is intended to be appropriate for use on most residential or light commercial development projects with common soil and rock types found in New Zealand. It is also intended to be flexible enough to be used on major earthworks projects, but may require more significant additions to the project‐specific details by the Geotechnical Designer. A separate short‐form version of this specification is being developed for smaller projects.


The following individuals provided a huge amount of voluntary time to develop these specifications:

  • Ross Roberts
  • William Gray
  • Tony Kao
  • Sally Hargraves
  • Tony Fairclough
  • Mark Stringer
  • Stuart Finlan
  • Marco Holtrigter

Professional input and review was provided by Liam Wotherspoon, Richard Neate and Hayden Bell

Documents for feedback

The specifications are read‐only, to encourage consistency between projects and to reduce the risk that can be introduced when customisations are made to the document which aren’t readily apparent to the contractor. Instead, project specific requirements which over‐ride the main specification are provided in a short “Project‐specific Specifications” document which describes the changes from the NZGS Specification.

The editable project specific documents are at the bottom of this list of files.

Tags : ConsultationDraftFeedbackGuidelineSpecification

Leave a Reply

More like this

Placeholder Image Coming

IAEG awards – nominate a colleague!

The International Society for Engineering Geology and the Environment (IAEG) has a number of highly prestigious awards which NZGS members…


Expressions of interest – AGS Landslide Risk Management Guidelines (AGS2007)

The Australian Geomechanics Society (AGS) in association with the New Zealand Geotechnical Society (NZGS) is undertaking a review and update…


Website feedback

Your website team led by Jordan Moll is investigating a project to upgrade the website. To help inform where the…


NZGS Slope Stability Guidance – Draft For Comment

In response to demand from our members, a sub-committee of the New Zealand Geotechnical Society has been developing slope stability…