View all publications

3 Site Classification

The overall purpose of a classification system is to provide local authorities with a best practice means of managing information about sites associated with hazardous substances and providing that information to interested parties. The specific objectives of the classification system are to provide a way to:

  • indicate what information is available about the adverse effects or risk a site poses, or may pose, to people or the wider environment, particularly whether the site is contaminated or not
  • ensure similar sites are identified in a similar way, to promote consistency and fairness
  • prioritise sites for further investigation, remediation or other action, or allocate resources
  • track actions taken, or changes in site status
  • record inaccuracies
  • provide an incentive for site owners to carry out actions that will reduce risks posed by their site
  • provide interested parties with an indication of the risks or adverse effects a particular site may pose.

The classification system consists of the following components:

  • site categories and descriptions (including a set of activities and industries that are likely to have used, stored or disposed of hazardous substances (Hazardous Activities and Industries List, or HAIL, see section 3.1)
  • a minimum set of information for each site and each category
  • processes for transferring a site from one category to another, and for dealing with special circumstances such as large sites and subdivided sites
  • recommended protocols for maintaining the register.

Local authorities obtain information about sites in a number of ways, and that information may be of varying quantity and quality. How a site is categorised and described depends on the presence or absence of hazardous substances and what risks or adverse effects those hazardous substances pose to the environment, including people. The following categories seek to ensure that sites are identified according to risk, and to acknowledge the variability of available information:

  • land-use information
  • contaminated land
  • error.

The 'land-use information' category includes both historical or current land use and information about hazardous substances, where available. The 'contaminated land' category describes sites that are contaminated according to the definition of contaminated land in the RMA. The 'error' category is for sites that were mistakenly entered on the database.

These categories may be used with an additional tag, 'under investigation'. The results of site investigations would either confirm the current category or result in a change of category. This tag can be applied to a site in any category.

3.1 Land-use information

This category is for sites for which some information is available about the land-use history, or the presence or absence of hazardous substances, or both. There may be a management plan in place or the site may have been remediated.

Note that sites in this category do not meet the RMA definition of contaminated land; sites that fit this definition are placed in the category 'contaminated land'.

The following descriptions are intended as a guide to the kind of information about a site that people may be looking for when, for example, seeking to subdivide former horticultural land, or purchasing a property. Local authorities may wish to make use of the descriptions, where applicable, when communicating with interested parties about a specific site. The descriptions may assist decisions about the site's use and suitability, and may indicate whether further action is advisable, such as a site investigation.

If a site has been associated with the Hazardous Activities and Industries List, it will be useful to indicate that:

  • the relevant land-use history has not been confirmed. The site has been reported as one that appears on the Hazardous Activities and Industries List, but the reported use has not been confirmed
  • the land-use history has been confirmed. The site has been confirmed as one that appears on the Hazardous Activities and Industries List.

The difference between these two points is explained in more detail below.

Hazardous Activities and Industries List

The Hazardous Activities and Industries List (HAIL) is a compilation of activities and industries that are known to have the potential to cause land contamination as a result of the use, storage or disposal of hazardous substances. The HAIL is a revision of the list of industrial activities first published in the Australian and New Zealand Guidelines for the Assessment and Management of Contaminated Sites (ANZECC, 1992). The HAIL is published as Contaminated Land Management Guidelines Schedule A (Ministry for the Environment, 2004c). An additional list, with typical hazardous substances for each HAIL category, is published as Contaminated Land Management Guidelines Schedule B (Ministry for the Environment, 2004d).

The HAIL is intended to help local authorities identify sites where contamination might have occurred. A listing on the HAIL does not indicate that the presence of a specific activity on a particular site will have resulted in the contamination of that site.

A generic activity involving hazardous substances may be listed irrespective of the industry (eg, petroleum storage). Alternatively, an industry may be listed on the basis that certain activities typical of that industry involve hazardous substances, and therefore all sites within that industry should be considered (eg, the timber treatment industry). Particular activities that are a small part of an industry and are generally localised within larger sites may be listed. For example, animal dip sites are listed, but farming is not, because dip sites are only a small part of a farm. Sites where hazardous substances have been used on a broad scale may fall within one of the specific HAIL listings (eg, HAIL No. 29 - areas where persistent agricultural chemicals have been used), or into HAIL No. 53 - any other facility or activity. However, as mentioned in section 1.2, local authorities may choose to address widespread contamination issues through their own strategies.

Describing a site as having the land-use history not yet confirmed identifies it for further attention. If the land-use history has not been confirmed, the site cannot be assumed to have been used for an activity or land use that has the potential to result in site contamination - that is, the activities described in the HAIL. The site cannot be assumed to have used hazardous substances until such information becomes available. There is no minimum information requirement for this description. Information sources may include a public complaint or unsubstantiated verbal history.

Confirming the land-use history does not mean there is any evidence of the presence or absence of hazardous substances. Sites that are confirmed as being on the HAIL, if accorded sufficient priority, should be further investigated. If further information indicates that a site has been mistakenly associated with the HAIL, the site should be moved to category 'error'. The evidence that confirms the land-use history, including sources, should be recorded. The information held should include one or more of the following:

  • personal knowledge, preferably a record of a visual inspection of the site by a suitably qualified or experienced local authority officer, and accompanied by a justification for inclusion in this category
  • documented evidence of the site use (eg, phone directory, trade directory, photographs, company information, community histories, local authority records) from two sources, defining both the location and use; one source may be adequate if the information is such that the location and use are certain, but a single phone directory entry would not normally be sufficient
  • documented evidence from past owners, workers, neighbours, hazardous substance suppliers or business customers, preferably with independent corroboration. Where the evidence is deemed to be sufficiently certain (affidavits may give greater confidence), independent corroboration would not be required. Where a report is from a seemingly unrelated party, or perhaps a competitor, independent corroboration would be important.

If a site has been investigated and some analytical information is available about the presence or absence of hazardous substances, providing a summary of the level of information held and what that information reveals about the site is useful. The date of the investigation(s) should be referenced every time information about the site is released. This ensures that recipients of the information are aware that concentrations of hazardous substances on the site may have changed after the investigation was undertaken because of activities on the site. If there is information available about both the land-use history and investigations of a site, both aspects can be provided or discussed together.

In assessing the information provided it is particularly important to check that the information held adequately considers both the on- and off-site land uses, because hazardous substances may migrate. The most sensitive exposure pathway and receptor combination should be considered. For example, an industrial site with on-site contamination that is within industrial guidelines may have off-site migration of hazardous substances in groundwater that renders a water supply on an adjacent site unacceptable. The source site would be likely to be placed in the 'contaminated land' category in this situation.

The following descriptions may provide a starting point.

  • The site has been investigated. Investigations indicate that there are no hazardous substances present at the site. The site was associated with an activity or industry that uses, stores or disposes of hazardous substances, but investigations indicate that hazardous substances are at background concentrations or below.
  • The site has been investigated. Investigations indicate that there are no hazardous substances present at the site. The site previously had hazardous substances present, but the site has been remediated to reduce concentrations of those hazardous substances to background concentrations or below.

Sites would be described as remediated and having no hazardous substances present via one of two mechanisms.

  1. The site has not previously been registered, and although an investigation report has been received by the local authority that demonstrates that the site had hazardous substances present, these have all been removed or destroyed.
  2. The site had previously been registered as 'contaminated land' or 'land-use information' but remediation (or further remediation) has been carried out and a site validation report has been received that indicates that there are no hazardous substances left on the site above background concentrations.

The information on the register should state that remediation has been undertaken at the site and that the site validation report indicates that the previous contamination has been eliminated and that any imported fill is free of hazardous substances.

For a site to be described as having no hazardous substances present, remediation would have to consist of destruction or removal of the hazardous substances. Immobilisation of the hazardous substances would not be sufficient, because in this instance the risks are being managed, rather than remediated.

The site has been investigated. Investigations indicate that there are hazardous substances present at the site, but indicate that any adverse effects or risks to people and the environment are considered to be so low as to be acceptable. This may apply where:

  1. The site has not been previously noted on the register, and although an investigation report has been received that shows the site has hazardous substances present, the report shows that the concentrations are so low as to be considered acceptable.
  2. A site has previously been noted on the register and investigations have revealed the presence of hazardous substances. The information indicates that the concentrations of hazardous substances are so low as to be considered acceptable.
  3. A site has previously been registered as 'contaminated land' but remedial action has been taken and a report demonstrates that any adverse effects or risks are so low as to be considered acceptable.
  4. A site has previously been described as having no hazardous substances present, and further information has become available that shows that an incident (eg, a spill) has resulted in the presence of hazardous substances. However, the concentrations of hazardous substances are so low as to be considered acceptable.
  • The site has been investigated. Investigations indicate that there are hazardous substances present at the site, but indicate that any adverse effects or risks to people and the environment are managed.

A management plan is a risk-management technique that seeks to ensure people do not come into contact with hazardous substances at a site. New owners of a site should be made aware of any restrictions on the site's use. The date of the investigation(s) should be referenced every time information about the site is released. This ensures that recipients of the information are aware that concentrations of hazardous substances on the site may have changed after the investigation was undertaken because of activities on the site.

Sites will usually be identified as being managed by one of four routes:

  1. The site has not previously been noted on the register, and although an investigation report has been received that shows the site has hazardous substances present, information indicates that a management plan has been implemented.
  2. A site has previously been noted on the register and further investigation has revealed the presence of hazardous substances, but a management plan has been implemented.
  3. A site has previously been registered as 'contaminated land', but some management action has been taken and a report demonstrates that any adverse effects or risks are so low as to be considered acceptable.
  4. A site has previously been registered as having no hazardous substances present, and although an incident (eg, a spill) has resulted in the presence of hazardous substances, a management plan has been implemented.
  • The site has been partially investigated. Investigations indicate that there are hazardous substances present at the site; however, there is insufficient information to quantify any adverse effects or risks to people or the environment. Reasons for considering the information insufficient may include:
    • the investigation undertaken does not address all the issues of concern on the site, such as all relevant environmental media (eg, groundwater, sediments)
    • the investigation was for only part of the site (eg, if the tank pits on a service station site were investigated, with no consideration given to other potential hazardous substance sources)
    • analysis for all likely hazardous substances associated with the present or past land use has not been undertaken (eg, copper, chromium and arsenic might have been investigated on a timber treatment site, but not pentachlorophenol (PCP), even though there has been documented use of the product on the site)
    • hazardous substances are known to have migrated onto the site from an adjacent site, but no investigation has been done to quantify the effects.

In rare circumstances, visual evidence may be considered sufficient to describe a site as partially investigated, such as where there is obvious extensive staining on, or in, the ground over an area known to have stored visually distinctive chemicals, or where chemicals are known to have been spilled.

Any information released about the site must clearly state what investigations have been undertaken on the site, as well as specifying what aspects of the site have not been investigated.

3.2 Contaminated land

This category is for sites where there are hazardous substances present that have, or are reasonably likely to have, significant adverse effects on the environment. Sites in this category fit within the RMA definition of contaminated land (see section 2). Local authorities must be satisfied that the evidence available is sufficient for a site to be placed in this category. The site may or may not have previously been on the register.

The following scenarios are likely to result in classification of land as contaminated:

  1. An investigation report shows the site has hazardous substances present that have, or are reasonably likely to have, significant adverse effects on the environment.
  2. The site has previously been registered as 'land-use information' and further investigation has identified hazardous substances present that have, or are reasonably likely to have, significant adverse effects on the environment.
  3. The site has previously been registered as 'land-use information', but a change to the site's use means that the site now has, or is reasonably likely to have, significant adverse effects on the environment.
  4. A site has previously been registered as 'land-use information', but as a result of site activities (ie, the release of hazardous substances), a report has identified the presence of hazardous substances that have, or are reasonably likely to have, significant adverse effects on the environment.
  5. Management measures put in place to control access to hazardous substances for a site registered as 'land-use information' are inadequate. The hazardous substances have, or are reasonably likely to have, significant adverse effects on the environment.

Determining whether a site is contaminated involves a thorough assessment of all exposure pathways in order to determine that the site has hazardous substances present and that those hazardous substances have, or are reasonably likely to have, significant adverse effects on the environment. The evidence required (such as a site investigation) and sampling and analysis should be in keeping with Ministry for the Environment guidelines. Where the local authority does not hold the expertise to evaluate a report, it is advisable to seek an independent peer-review.

3.3 Error

This category is for sites that have been entered on the register in error. Information shows that the site has never been associated with any of the specific activities or industries on the Hazardous Activities and Industries List.

When a site is initially identified as 'land-use information', the information held needs to be reviewed. If further information or investigations clearly show the initial registration was incorrect, then the site would be assigned to 'error'. The 'error' category is for the discovery of mistakes at any point, from any category, not just at the verification stage (eg, to reclassify a duplicate entry for a site that has erroneously been entered on the register).

Where certain details about a site are entered incorrectly (eg, the wrong street address or occupier's name), it may be more appropriate to amend these details (rather than categorise the site as 'error') and re-enter the same site with the correct details. Good data management protocols should ensure that amendments are recorded and explained. Enquiries about sites registered under this category should be responded to with 'no evidence about past or present hazardous activities or industries is held'.

Keeping a record of a site entered onto the register by mistake should ensure it is not re-identified in the future. The reasons for the original entry and reasons for the change to this category must be given. If sufficient evidence is available, a landowner may prefer the site to be registered as 'land-use information' to show that the absence of hazardous substances has been verified.

Other relevant local authorities should be made aware of sites assigned to 'error' to ensure any misinformation is corrected. Territorial authority files may need to be altered to correct any mistakes.

3.4 Sites adjacent to registered sites

When information is received indicating that a site should fall within a 'contaminated land' or 'land-use information' category, a decision must be made as to whether adjacent sites might have been affected by hazardous substances migrating across site boundaries and whether those adjacent sites should be recorded on the register. Migration of hazardous substances could occur by:

  • transport of dust by wind
  • transport of sediment by stormwater
  • flow of a spilled liquid across a boundary
  • migration of vapours or gases through the ground or above the ground
  • migration of non-aqueous-phase liquids, otherwise referred to as phase-separated product, in or on groundwater
  • migration of dissolved hazardous substances in groundwater
  • physical movement (eg, digging and removal of soil or wastes) across a boundary.

Adjacent sites could be noted as falling within HAIL No. 52 (any site that has been, or could have been, subject to the migration of hazardous substances from hazardous substances present on adjacent sites) and categorised as 'land-use information' and described as follows:

  • the land-use history is not confirmed - if an investigation report suggests that migration is reasonably likely to have occurred, or
  • the site has been partially investigated - if there is evidence of migration of hazardous substances (eg, a spill extending onto an adjacent site, which has been verified through testing), but no information about whether the hazardous substances have, or are reasonably likely to have, significant adverse effects on the environment.

In either instance, flagging the site for further investigation would be warranted.

If sampling is undertaken on the adjacent site, and hazardous substances are present and are having or are reasonably likely to have, significant adverse effects on the environment, it may be appropriate to register the adjacent site as 'contaminated land'. Where sampling the adjacent site shows the presence of hazardous substances at concentrations unlikely to have significant adverse effects on the environment, registration as 'land-use information' would be appropriate. If the sampling is not representative of the entire site, the site should be registered as 'land-use information' and noted as being partially investigated.

For sites further away from the source site than the immediately adjacent site (ie, remote sites), there is no justification for registration unless there is clear evidence that migration has occurred across the adjacent site and is affecting more remote sites. However, if a risk assessment of a major spill shows that remote sites are at risk, it may be prudent to note such sites on the register as 'land-use information', noting that the land-use history is not confirmed and pending further investigations. The remote sites would not be considered to be 'contaminated land' unless further investigations indicate that hazardous substances are present and are having, or are reasonably likely to have, significant adverse effects on the environment.

3.5 Multi-title or subdivided properties

New Zealand's land tenure system is based on a unique legal description or title for each parcel of land. Many properties will consist of a single parcel of land with a single legal description. However, some properties, particularly larger ones, may consist of several 'lots', each with a title.

For the purposes of this guideline, a site can contain one or many lots. For a site with multiple lots (and therefore multiple legal descriptions), each legal description should be recorded on the register. A site number (or similar) will indicate there is one site comprising multiple lots.

Where a multi-title block of land has been used by one company, but an investigation shows that hazardous substances were used, stored or disposed of only on some lots within that block of land, only the affected or associated lots should be identified in the site record. A note could be made in the site details listing the extent of the whole site, but clearly stating that only some of the lots within the block are registered.

Similarly, large blocks of land consisting of a single title may not have been affected over the whole site (eg, a farm). Using the title to identify the site means that the whole site must be given the same classification. To overcome this, the register entry should clearly note that just a limited area is affected. The affected area should then be delineated using a map reference from a topographical map (1:50,000) and any other appropriate information.

Subdivision of a large site will create several new sites, each identified by a new title. Where a site originally contained multiple lots, sale of individual lots to new owners would necessitate the creation of new sites to represent this. If a site was on the register at the time of subdivision, a decision must be made how to classify each of the new titles, and how to record the information about the original site on all the new entries.

If no information is available to differentiate effects on different parts of the original site, all the new titles should automatically default to the classification of the original site. The new titles should include a reference to the original site.

Where there is sufficient information from the original classification, newly created sites may be given a different classification to the original site. This would arise if an original investigation report was sufficiently detailed to show that contaminating activities were restricted to particular parts of the original site, or the results of sampling showed a clear differentiation of effects. If there is sufficient evidence to show that a new site created from an old classified site did not have any contaminating activities associated with it (including consideration of hazardous substance migration), or there are sufficient sampling results to show that there are no hazardous substances present, or that any hazardous substances present are unlikely to have significant adverse effects on the environment, then the site may be placed in the 'error' category or 'land-use information' as appropriate. A new site created from an old site assigned 'error' should not be entered into the register. In all other circumstances, a new site would be assigned an appropriate category in order to provide an audit trail.

3.6 Classification process

Information about sites can come from a variety of sources. Irrespective of the source of the information, once the local authority becomes aware of a site, the site details need to be entered on the register and verified.

There are a number of steps to classifying sites, which will vary depending on the type and nature of information held. Verifying the information held and notifying the site owner are the two fundamental processes that will occur, irrespective of the category the site is placed into.

The verification process aims to ensure the required amount of information has been provided and that it is reliable. The exact method of verification will vary depending on the type of site. For example, where there is information about the HAIL then the local authority should check (among other things) historical information sources and aerial photographs. Verifying information held in a site investigation report, however, will involve checking the data against appropriate guideline values and determining the quality and completeness of the information obtained.

A rigorous checking process is important to ensure that information placed on a register is as accurate as possible. This will help to make sure that information held by the local authority is fair and reasonable to the property owner, and useful for other interested parties.

Notifying the site owner is a key part of placing a site on the register or changing the site category. Notification provides an opportunity for site owners to view information about their site, add information and correct mistakes. Provision should be made for accepting and considering an owner's objections. The notification process may vary between local authorities, and will depend on the type and nature of the information held about the site. A general process is described in the following sections as a starting point. This process assumes that information verification and owner notification will be applied during both the initial registration process and as part of any transfer from one category to another.

3.6.1 Verification

To provide an audit trail, and for tracking whether a particular document or record has been verified, it is recommended that local authorities implement a recording process for verification. Relevant details should be noted, such as date of receipt, whether the document or record is verified or not verified, date of verification, verifier's signature (or electronic identification) and cross-references to any other documents used in verification.

If the contents of a document or other piece of information cannot be verified or are found to be incorrect, the document should be marked accordingly, with a reference to the contradictory evidence.

3.6.2 Classification and consultation process

The process of verifying information and notifying the site owner of the local authority's proposed classification of their land, needs to be clear and robust. The process is outlined below and summarised in Figure 1.

a) Information is received about a site: for example, an environmental investigation, report of a spill or release of hazardous substances on a site, or an indication that a HAIL activity has occurred, or is occurring, on the site.

b) Available site details are recorded on the register: if the site is not on the register, site details such as address and legal description (see Appendix A) are entered on the register and the site is registered as 'land-use information'. It may be appropriate to note that the land-use history has not been confirmed.

c) Information is verified: all information received by a local authority should be carefully considered and verified. Where appropriate, the information should be reviewed against the relevant Ministry for the Environment guidelines. If the information is found to be incorrect, the site should remain in its current category, or be classified as 'error', and no owner notification is required.

d) Officer prepares a report: the local authority report should include:

  • the site history
  • if there is a report on the site:
    • the name, date, author and summary details
    • the guidelines the site was assessed against, if applicable
    • a summary of the report's findings on whether the concentrations of hazardous substances on the site meet or exceed appropriate guideline values, if applicable
    • the report's assessment of whether there are, or are likely to be, significant adverse effects on the environment, if applicable
    • reference to any site-specific assessment or management plans that aim to reduce the exposure to hazardous substances present on the site, and therefore any risks, if applicable
    • the officer's comments on the report
  • the proposed category under which the site will be registered on the database.

e) Site owner is notified: the owner is provided with a copy of the local authority report, including the category the local authority will recommend the site be classified under (see Appendix B for an example letter). The owner is provided with a reasonable period of time (eg, 20 working days) to provide additional information, to challenge the proposed classification, or to correct any mistakes. The site owner is advised when and where the report will be presented to the senior local authority officer or manager for a decision on final classification, and is invited to attend if they wish.

f) Report is updated: the local authority officer updates the report with any additional valid information provided by the site owner. If the site owner requires more time to compile additional information, a new date for presenting the information to the senior officer or manager should be set.

g) Report is presented: the local authority officer presents the report and the recommended classification to the senior local authority officer or manager. The site owner (if present) has an opportunity to provide input.

h) Decision is made confirming or changing the recommendation: the site owner should now be notified of the decision and reasons (see Appendix B for an example letter). The owner is provided with a reasonable period of time to provide more information, or to challenge the proposed classification. If no response is received, the site category is established. The information is then available to be used in response to enquiries or passed on to the relevant territorial authority.

If the classification is challenged, the site owner may be able to suggest which category would be more appropriate for their site. If agreement cannot be reached, both the site owner and the local authority officer should present their proposed categories to an appropriate senior local authority officer, manager or committee. The committee or senior officer would then decide which category the site should be assigned to. The timeframe for this process should be determined on a case-by-case basis, as agreed by the local authority and the site owner.

Figure 1: Site classification process

3.6.3 Site classification review

A review of a site classification may result in a change to the original category. The review could be initiated by (for example):

  • further investigative information being obtained (including remedial or management action)
  • land-use or district plan zoning changes, or the site being subdivided
  • information supplied from the owner following a hazardous substance release incident
  • information supplied from another party following a hazardous substance release incident (eg, the hazardous substances release database administered by the Environmental Risk Management Authority New Zealand).

In most circumstances, the regional council will receive the information and initiate and carry out the review. Where a territorial authority becomes aware of information contrary to its understanding of the site's current status, it should notify the regional council of the circumstances so that it can initiate a review.

The site owner would be notified of the review, proposed new classification and any additional information. Unless the reclassification is into the 'error' category, the owner should be given the opportunity to provide additional information or make an objection, as outlined in the classification process. The owner should be notified before the decision is recorded in the register. The proposed category would be noted in the register and the site flagged as 'under investigation'. The existing classification would remain in force until the proposed category is finalised.

A site owner may initiate a review by providing new information. The local authority should then carry out the review within a reasonable timeframe, giving the owner the opportunity to comment on, or contest, the proposed reclassification, as outlined in the classification process.

Once the regional council has completed a review, the relevant territorial authority should be notified of the result so the information is available for the territorial authority to use (eg, for planning decisions or public requests for information).

3.7 Recommended register entries

As discussed in section 1.3, this guideline is not intended to describe the specific structure or design of a register, electronic or otherwise. The aim is to provide a recommended minimum set of information to be held in the register, as set out below. The register should be divided into three subsets of information: site details, site status, and a record of information transfers and releases.

3.7.1 Site details

Information in this category should include (if known or relevant):

  • site location
  • legal description
  • ownership
  • past and present site use
  • hazardous substances stored or used
  • local authority file references
  • references to other related sites (for multi-title and subdivided sites).

3.7.2 Site status

The site status details would include a series of records or file notes created each time a site is classified or reclassified. The reasons for the classification, investigation report references, hazardous substances and concentrations, pathways and receptors of concern, and environmental guideline values used in an assessment should all be noted. A flag indicates that the site is under investigation (ie, additional information is currently being collected or reviewed). Additional details − such as the local authority officer's name, the date of the classification, and whether a record is current or superseded − provide an audit trail.

Superseding a record would occur if either:

  • a new classification has been made and is now current, or
  • the site has been replaced by a new site following subdivision or title amalgamation; in this case, cross-references would be created between the new site(s) and the superseded site(s).

3.7.3 Record of information transfers and releases

A record of information transfers and releases should be noted for each site. Recording public requests, decisions made with respect to those requests, and transfers to a territorial authority or other agency (whether routine or a one-off transfer) helps provide an audit trail.