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2 Investigating and Reporting

Contaminated site management can be broadly classified into the following reporting stages, which track the site investigation process from inception to remediation or long-term management:

  • preliminary site investigation report
  • detailed site investigation report
  • site remedial action plan
  • site validation report
  • ongoing monitoring and management plan.

Consultants' reports normally address these stages. Reports may be prepared to satisfy the requirements of sale and purchase agreements, permit applications or for other purposes in addition to documenting the investigation and clean-up procedures considered and adopted.

Report stages may be presented separately, usually where large and complex sites are being considered, or they can be combined. However, each report must stand alone and have enough information to be clearly and readily understood by the appropriate persons reviewing it.

If there is already information prepared on a site, and that information is still available, a summary of that information should suffice in subsequent reports. If there is already a relevant report about a site (eg, at a local authority on an identified file), who holds this file and its location should be disclosed in the report.

Where the report(s) being prepared will be used for a resource consent, the appropriate additional information required by s.88 and the Fourth Schedule of the RMA may be included in the report or attached to it. Note that some local authorities require permit application information to be presented on specified forms.

The following five stages may contribute to a report. Not all stages may be necessary, although any exclusion should be clearly justified in the report. Chapter 3 provides a detailed checklist of what should be included, as a minimum, for each stage. Note particularly the single-page summary checklist, which should be the first page of your report. The summary checklist will serve as a quick guide to the contents and completeness of the report.

2.1 Stage 1 – Preliminary site investigation report

The purpose of the preliminary site investigation report is to present the site history.  It should:

  • identify any known local information providing baseline data on soil and groundwater quality near the site
  • list in order all past and present activities at the site that involved the storage, production, use, treatment or disposal of materials that could contaminate the site
  • identify the types of materials that could contaminate the site and where such contamination could have occurred
  • describe the current site condition, and the contents and results of any known previous assessments
  • cite any records from relevant authorities detailing site condition, including the data and results of any risk-screening (see Contaminated Land Management Guidelines No. 3: Risk Screening System, Ministry for the Environment, 2004) or other assessments undertaken
  • identify the likelihood of contamination
  • make a preliminary assessment of that site's contamination based on the qualitative and quantitative information available
  • assess the need for further investigation at the site, specifically with reference to the current and/or proposed land uses and/or the potential environmental impact.

The risk-screening system is a useful method to assess potential risk, and while mainly employed by local government should also be considered as a tool for use by environmental consultants. Input values sufficient to allow a risk screening to be undertaken should be included in the preliminary site inspection.

The site history is fundamental to the preliminary assessment, and may be used to assess the likelihood of the site having become contaminated. It is important to review and assess all relevant information about the site, including information obtained during a site inspection. If a complete site history clearly demonstrates that site activities have been non-contaminating, there may be no need for further investigation or sampling.

However, if contaminating activities have or may have occurred, or if the site history is incomplete, it may be necessary to undertake a preliminary sampling and analysis programme.  The results of such an investigation should be included in the preliminary site investigation report as part of the basis for assessing the need for a further, more detailed, site investigation.

2.2 Stage 2 – Detailed site investigation report

This should give comprehensive information on:

  • issues raised in the preliminary inspection
  • the type, extent and level of contamination anticipated
  • the nature of samples collected and the sampling procedures followed, including quality assurance / quality control requirements
  • the analyses undertaken, methodologies used and laboratory quality assurance / quality control procedures.

The site investigation report should also assess:

  • the actual extent and concentrations of contaminants in all appropriate media at the site
  • any likely dispersal in air, surface water, groundwater, soil and dust from the detected contaminants
  • where applicable, the location and magnitude of any on-site or off-site impacts on soil, water, sediment and biota
  • any potential effects of contaminants on public health, the environment and structures
  • the adequacy and completeness of all information used in decisions on remedial options
  • if clean-up, management or ongoing monitoring is intended at the site.

Any investigation undertaken should comply with Contaminated Land Management Guidelines No. 5:Site Investigation and Analysis of Soils (Revised 2011) (Ministry for the Environment, 2004).

The results of chemical analysis of the soil sampled are to be compared with appropriate soil contaminant standards or soil guideline values.  Soil contaminant standards have been derived for a group of priority contaminants and a set of scenarios that are legally binding as gazetted under the National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health.

Where soil contaminant standards are not applicable, soil guideline values may be derived in accordance with the methods and guidance on site-specific risk assessment provided in the Methodology for Deriving Standards for Contaminants in Soil to Protect Human Health (Ministry for the Environment, 2011). Alternatively, generic soil guideline values (such as those in the industry-based guidelines published by the Ministry for the Environment) may be applied. The assumptions on which those guidelines are based must be shown to apply to the site and surrounding conditions under investigation.

There are computer tools that can help to assess risk to human health and ecology. Where these are used, describe them in the site investigation report (including what they are designed to do) and detail what data was used, what scenarios were examined and the underlying algorithms. Sufficient information should be provided so that the report reviewer is able to replicate the risk assessments.

If the results of the detailed site investigation indicate that the site poses unacceptable risks to human health or the environment - on-site or off-site, and under either the present or proposed land use - then a remedial action plan needs to be prepared and implemented.

Note that all areas of interest to the local authority, the consultant or their client(s) may not lie within the property boundary. In this case, the boundaries of interest (the area of contamination) should be clearly defined. Any investigation should extend so as to clearly bound the contamination related to the source(s) or site in question. If contamination extraneous to the site being investigated is found, the appropriate local authority should be advised. This can be done either via the site investigation report or, if immediate adverse effects are detected or anticipated, as soon as practicable.

2.3 Stage 3 – Site remedial action plan

Once the site has been identified as requiring remediation or management, the remedial action plan should be prepared as follows.

  • Set remediation or management goals that ensure the site and any relevant additional land contaminated by site activities will be suitable for its current or proposed land use and will pose no unacceptable risk to human health or the environment, either on-site or off-site.
  • Document in detail all risk-reducing procedures and plans to be implemented to achieve an acceptable level of risk for the current or proposed site's land use.
  • Establish a recording mechanism to ensure activities proceed as detailed in the remedial action plan.
  • Establish the environmental safeguards required to complete the remediation in an environmentally acceptable manner.
  • Identify and include proof of the necessary approvals, permits or licences required by regulatory authorities to undertake remediation.

Where site-specific clean-up levels are to be developed by applying proprietary risk assessment methods, the consultant must consult the relevant regional council or unitary authority to discuss appropriate procedures. Guidance on when it is appropriate to carry out a site-specific assessment and how to derive site-specific soil guideline values is given in Methodology for Deriving Standards for Contaminants in Soil to Protect Human Health (Ministry for the Environment, 2011a).

Systematic and clear plans should be made of remedial work to be undertaken, ensuring among, other things that dates, quantities, sampling, excavation and disposal locations will be recorded.  Local background conditions should be verified within the remedial action plan. Such data and any management or regulatory decisions made during or following the remedial process will be required for reporting stages 4 or 5 (or both).

2.4 Stage 4 – Site validation report

After remedial or management action, the conditions at the site must be assessed to validate that the objectives stated in the remedial action plan have been achieved. A site validation report detailing the application of the remedial action plan, any variances from the proposed plan and the results of validation is required. The application of the remedial action plan should be assessed both in terms of the management and remedial goals established, and how remediation was undertaken.

This will vary according to:

  • the degree of contamination originally present and the remediation goals set for the site
  • the type and extent of remedial processes that have been carried out
  • the current or proposed land use.

Validation must confirm statistically that the remediated site complies with the clean-up criteria set for the site in the remedial action plan. For further guidance on statistical sampling and confirmation, we recommend that consultants see the New South Wales Environment Protection Authority's Contaminated Sites: Sampling Design Guidelines (1995). The United States Environmental Protection Agency's Methods for Evaluating the Attainment of Cleanup Standards (1989) is also useful.

A number of computer tools can also assist with sample planning and the assessment of statistics related to sampling. As in the site investigation, the report should give details of the programme and enough information to let the reviewer replicate the assessment.

The site validation report must assess the results of the post-remediation testing against the clean-up criteria stated in the remedial action plan. Where targets have not been achieved, the reasons for this must be stated and additional site work proposed to achieve the specified remedial action plan objectives should be listed. If any contingency plans were detailed in earlier reports, they should have been implemented before the site validation report is submitted.

The site validation report should also include, where possible, information confirming that all the requirements of regional council, unitary and territorial authority or other planning authority licences or permits have been met. In particular, documentary evidence should be included to show that any disposal of contaminated material off-site has been done or will be done in accordance with the remedial action plan, and with the requirements of the disposal site and the relevant local authority.

2.5 Stage 5 – Ongoing monitoring and management plan

The requirements for an ongoing monitoring and management plan for the site should be assessed where:

  • full clean-up is not possible or preferable
  • monitored natural attenuation is selected as the preferred remedial option
  • on-site containment of contamination is proposed.

Where remedial goals are achieved in accordance with the remedial action plan, as confirmed by the site validation report, there may still be a requirement to provide an ongoing monitoring and management plan. In accordance with s.15 of the RMA, this may be required as supporting information for an application for a discharge permit, if this is required to authorise contaminants that remain on-site or off-site. In this case, the appropriate requirements of s.88 and the Fourth Schedule of the RMA should also be included. The relevant regional council or unitary authority should be contacted to confirm the requirements in each area.

A monitoring programme should detail the proposed monitoring strategy, what will be monitored, the location and frequency of monitoring, and the reporting requirements (format, content and frequency). It should also state the proposed period for reviewing the monitoring and management plan.

Reporting of the results of monitoring falls outside the scope of these guidelines. Where ongoing monitoring or site management is required to be reported as a condition of a resource consent, the reporting requirements will be in accordance with those set down by the consent. However, the requirements proposed in the monitoring and management plan are likely to form the basis for proposing conditions of any ongoing reporting under a resource consent. Where monitoring or management is governed by a non-statutory instrument, any additional requirements will be as stated in that instrument.

Where a management plan is used as the primary means of reducing risk, its application and effectiveness must be reported on, no less than annually, to the relevant local authorities. Without such reporting, it will not be possible for the local authorities to be confident that the risk from the contamination is being managed.