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1 Introduction

1.1 Purpose

This guideline on Site Investigation and Analysis of Soils is the fifth document in the Contaminated Land Management Guidelines (CLMG) series produced by the Ministry for the Environment. It is designed to be used in conjunction with other documents in the series and other Ministry contaminated land publications. The purpose of the guideline is to promote a nationally consistent approach to the investigation and assessment of contaminated land.

Specifically, the guideline provides:

  • best practice that should be followed for the sampling and analysis of soils on sites where hazardous substances are present or suspected in soils in New Zealand
  • guidance on the principles governing the interpretation of the data obtained.

New Zealand guidance documents that address aspects of the overall objective of this guideline are available, including guidelines on the investigation, assessment and monitoring of land potentially contaminated by gasworks residues, petroleum hydrocarbons, timber treatment chemicals and sheep dips.  These documents are available from the Ministry for the Environment website (  Many of the New Zealand and overseas documents used in the preparation of this guideline are listed in the References and Additional Information sections.

1.2 Target audience

This guideline is aimed primarily at contaminated land practitioners and regulatory authorities - in other words, those undertaking and auditing contaminated site investigations. Owners, potential owners or occupiers of sites where hazardous substances are present or suspected may also find this guideline useful for reviewing the work undertaken, or assessing tenders or proposals for work. The guideline could also be helpful to other stakeholders, such as the owners or occupiers of land adjacent to a site where hazardous substances are present. 1

The guideline does not set out to provide definitive information required by every stakeholder, but we do provide references to other publications for more specific information not presented here. The appendices also contain supplementary technical information.

The overall content of the guideline should assist regulatory authorities and other stakeholders using or assessing contaminated land reports to:

  • understand the stated outcomes of the reports in the context of the site investigation objectives
  • understand the uncertainties associated with the collection and analysis of soil samples and the interpretation of the ensuing data
  • assess whether best practice and/or minimum requirements have been met and work has been undertaken with competency.

1.3 Scope

Site Investigation and Analysis of Soils provides guidance on how to gather information and collect soil samples to provide data that allows an assessment of land where hazardous substances are present or suspected. This includes formulating data quality objectives, designing the sampling strategy to meet the objectives of the investigation, quality assurance for analysis, and data interpretation. A flow chart summarising the recommended staged approach to site investigation is presented in Figure 1.

The guideline is primarily concerned with soil sampling, although the same general principles could equally apply for the investigation of other media such as air, groundwater or surface waters impacted by hazardous substances. It does not provide information on collection techniques for media other than soil, although these may also be integral to a detailed site investigation. The guideline is restricted to soils containing metals, and volatile and semi-volatile organic compounds. Other chemicals are not addressed.

Figure 1: Recommended approach to site investigation

1.4 Minimum standards

This guideline establishes current best practice for undertaking a site investigation for hazardous substances and promotes recommended minimum requirements. Some organisations initiating the investigation of land could require that the investigation is undertaken to a degree that may not meet all the minimum requirements, or may improve on the minimum guidance presented here. It is also possible that the best practice/minimum requirements set out in the guideline are not met. In such cases, the circumstances should be documented in the site investigation report and the implications for the investigation objectives clearly stated.

1.5   Changes from the 2004 version

Updates have been made in the 2nd edition of these guidelines (October 2011) to the following.

  • updated website URLs
  • updated references to other documents and guidelines
  • references to the Resource Management (National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health) Regulations (to take effect on 1 January 2012).

1 In line with other guidance in the CLMG series, in this document 'site' means an area of land, as defined by a legal description or part of a legal description, which is under investigation.