1. Introduction

Soil contamination is a significant concern in New Zealand, with historical land uses such as coal gas works, timber treatment, sheep dips, closed landfills, and pesticide- and herbicide-intensive horticulture leaving dirty legacies for both private landowners and the general public. However, the existing controls on contaminated land under the Resource Management Act 1991 (the RMA) have been described as either absent, inadequate or inappropriately applied.1

The proposed National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health (the NES) was announced by the Environment Minister yesterday, and is the first national control on soil contamination that has been offered since RMA was enacted.

The NES has been approved by Cabinet, and is now awaiting the attention of MfE and the Parliamentary Counsel, who will prepare draft regulations. Once finalised the regulations will be submitted to Cabinet and then to the Governor-General for final approval. The Minister for the Environment has announced that he expects the NES to be gazetted by an Order in Council to take effect on 1 September 2011.

There have been several key changes to the NES as it has made its way through the development stages. Most notably, the acceptable contaminant thresholds have been lowered, and the planning control framework tightened so that development of potentially affected land is a controlled, instead of a permitted, activity.

The NES will require all territorial authorities to control the development (being land-use changes, subdivision, and soil disturbance) of land affected or potentially affected by contaminants. The likelihood of a site being contaminated will continue to be assessed at first instance by previous land uses that are known to bring risks of contamination.

  1. Noticeable Omissions

The most noticeable change from the discussion document has been the title of the NES, and is a change which highlights a key criticism of the NES from environmental interest groups. The aim of the NES, to ‘protect human health’, has been made explicit in the title; effects on the natural environment are not addressed. The NES acknowledges that boron, copper and chromium III in particular can be harmful to plant life at levels far below those at which human health is adversely affected. The Environment Minister explained yesterday that the human health focus of the NES is based on advice that there is insufficient robust data to base toxicological limits for protection of the environment. The Minister has welcomed evidence that would assist in setting such limits. Whether this is a genuine offer or political manoeuvring disguised as such remains to be seen. Unless persuaded otherwise, in the interim effects on the natural environment will have to be addressed on a case by case basis. The definition of ‘contaminated land’ in the RMA will still incorporate contaminant levels that have, or are reasonably likely to have, significant adverse effects on the environment, notwithstanding the fact that human health is not threatened. However, there is a risk that the NES’s prioritisation of human health issues will affect how the RMA is applied in practice.

As has been noted in the past, the NES does not seek to apportion liability for contamination that occurred before the enactment of the RMA. Further, it does not provide for remediation of sites, except as conditions of consent on applications to develop affected, or potentially affected, land.

  1. Mechanisms

The NES identifies two important issues that require intervention, and proposes two key mechanisms to address them.

  1. Soil Contaminant Values

One of the issues is the inconsistent and inappropriate use of contaminant guideline values to assess the effects of affected and potentially affected land. The proposed solution is a set of soil contaminant values (SCVs (health)) for twelve soil contaminants2 based on the risks each presents to human health, and methods for applying them. If soil contaminant concentrations exceed SCVs (health), the development will be classed as restricted discretionary. Otherwise, the activity will be controlled (i.e. consent must be granted, but conditions can attach).

The term used in the discussion paper, Soil Guideline Values (SGVs (health)), is slightly different; importantly SGVs (health) are described as the concentrations at which exposure to a contaminant is judged to be acceptable because any adverse effects on human health for most people are likely to be no more than minor. The effects on human health at or below an SCV, by contrast, are not so absolutely defined, but are instead described as dependent on the intended land use. Where the land use will result in greater human exposure to contaminants than for one of the five generic land use scenarios, a site-specific SCV (health) must be derived.

The SCVs (health) in the NES are generally considerably lower than those in the draft version, reflecting comments made in numerous submissions on the discussion document. However, the SCVs (health) for boron, chromium III and copper have been set at ‘No Limit’, with a footnote explaining that the derived values for human health exceed 10,000 mg/kg.

  1. National Planning Controls

The second issue is that the controls on development of potentially contaminated land are largely absent, inadequate and inconsistent. To address this, the NES would classify certain activities at the time of development of land that is, or could be, affected by soil contaminants. Less restrictive activity statuses would apply where the contaminant levels are below SCVs, which is proved by the provision of a site investigation report to the consent authority. The regime will essentially allow councils to verify on a site specific basis the entries on its contaminated sites register that are based on inconclusive historical land use data, without having to undertake such investigations itself. The NES envisages four such controls:

  1. permitted activity status for the removal of underground petroleum storage systems, impacted soil, and associated subsurface soil sampling;

This is a new clause that relates specifically to underground petroleum storage systems. No such control existed in the discussion document, but was requested in the submission of the Oil Industry Environmental Working Group.

  1. permitted activity status for small scale (25 m 3) and temporary soil disturbance activities (1 month duration) including subsurface investigations;

The former version of this statement was restricted to subsurface investigations of land to determine the presence, extent and nature of any contamination, and did not have volume or time limits.

  1. controlled activity status for the development of land where the risk to human health from soil contamination does not exceed the SCV (health) for the intended land use; and  

Should the requirements of the rule not be met, the activity will default to restricted discretionary. The discussion version of this clause permitted the use, development or subdivision of land where the risk to human health from soil contaminants was assessed as being acceptable for the intended land use. What was acceptable was based on SGVs.

The change to a controlled activity status from permitted could discourage landowners from taking the preliminary steps involved in developing land. While there is little or no consenting risk, there will be red tape to navigate. From the point of view of local authorities the change will allow recovery of costs that would otherwise be incurred as part of permitted activity monitoring.

  1. restricted discretionary activity status for the development of land where the risk to human health from soil contamination exceeds the SCV (health) for the intended land use.

Again, the previous version of the control was phrased in terms of acceptable risk, which was based on SGVs. What is interesting is that the partnering clause that assigned restricted discretionary activity status where there was insufficient evidence to confirm the risk is missing from the NES. This provision covered situations where no site investigation report was provided to Council on a proposal to develop potentially contaminated land, and was intended to incentivise such provision.

The current form accomplishes essentially the same thing, but with more concise drafting. Councils will decide whether the level, nature and extent of soil contamination has been accurately or adequately characterised and whether the site is suitable for the intended land use. However, the NES does not now explicitly address the situation where the investigation has been provided, but is of poor quality, or is inconclusive. It would appear that the activity would become restricted discretionary, or could be covered by a request for further information by the consent authority.

One criticism of the NES has been that it assumes a high level of institutional skill and knowledge in local authorities, to the extent that auditing and analysis of site investigation reports would be simple. This may not be the case, especially in less well-resourced areas.