Graeme Proffitt surveys the changing attitudes and approach to management of land contaminants
WasteMINZ became the “home” to contaminated land practitioners and a forum for the exchange of ideas back in the 1990s, not least because the remediation of sites by “dig and dump” generated a lot of waste soil that ended up in landfills; essentially we were core business. WasteMINZ also came into existence around the time that contaminated land started hitting the headlines in New Zealand. It is, therefore, appropriate to look back over the past 30 years at the key drivers for the practice that developed, where we are at the moment and what the future might hold.
This is a personal view, but I must acknowledge the memories of and input from my former colleague Keith Delamore, who was responsible for me entering the industry 25 years ago.
The early days
Contaminated land is nothing more than unwanted chemical residues in the ground. Historically, chemicals got into the ground through deliberate disposal, an acceptable practice of the time, and accidental releases from storage or transport. Many of our early industries were responsible for ground contamination, in particular, our petroleum storage and distribution, timber treatment and coal gas manufacturing industries. Agricultural practices also caused unwitting contamination, through the use of pesticides and fertilisers. A legacy of ground contamination, therefore, existed in New Zealand well before anybody had given much thought to its effects, let alone investigation and remediation. However, during the late 1980s greater environmental awareness, the development of new legislation, particularly the Resource Management Act (RMA), and some major contamination incidents drove the beginnings of the contaminated land sector in New Zealand.
One headline incident was the aviation fuel spill by Shell Oil at its Freemans Bay facility in 1986. Subsequently, the oil industry became a mainstay of the contaminated land consulting industry over the next 30 years, driven by rationalisation of the oil industry’s storage and retail supply assets for economic reasons, and concern by overseas parent companies for their environmental liabilities. Timber treatment sites, gasworks and redevelopment of orchard land subsequently became important site types.
The role of guidance and regulation
The big push from government arose through concern for the health effects of the use of timber treatment chemicals. This resulted in the formation of a National Task Group on Site Contamination in the late 1980s, and the first major government-funded investigation was carried out at the Waipa Mill in 1991/92. Around the same time, the Ministry for the Environment (MfE) commissioned a report, the “Worley Report”, to estimate the number of potentially contaminated sites in New Zealand. The resultant number, 7200, is only a fraction of the number of sites now thought to exist.
No New Zealand contaminated land guidance existed at this time, although some soil guideline values (SGV) for dioxins had been developed for Waipa. The first document with some New Zealand input was the Australian and New Zealand Environment Conservation Council (ANZECC) Australian and New Zealand Guidelines for the Assessment and Management of Contaminated Sites, published in 1992. This provided SGVs for a few substances and the broad framework for conducting a site investigation, including the concepts of preliminary and detail site investigations and site-specific assessment. The first solely New Zealand guidance was the Health and Environmental Guidelines for Selected Timber Treatment Chemicals which appeared in draft form in 1993 and was finalised in 1997. This document provided detailed guidance on soil and groundwater techniques and SGVs for a suite of chemicals primarily aimed at the timber industry but which could also be applied to other site types. MfE had also identified gasworks and petroleum sites as being important to the New Zealand context, with guidance for gasworks being published in draft form in 1996 (finalised 1997) and for petroleum hydrocarbon sites in 1997 (finalised 1999). The latter drew on work by the Total Petroleum Hydrocarbons Criteria Working Group in the United States, putting New Zealand at the cutting edge (to the envy of Australian practitioners for several years). Sheep-dip guidelines were also issued in 2006. Intended guidance for orchard sites, which were being subdivided and developed on the fringes of some of our cities, never eventuated.
Following the release of the Worley report, there was increased interest by regional councils in understanding the scope of the issue in their regions, with the development of site databases and regional strategies for managing contaminated sites. Given the privacy issues, MfE issued draft guidance on contaminated site information collection in 1996. However, it took until 2005 for a definition of contaminated land to be inserted into the RMA and for regional and territorial local authorities to be provided with functions specifically related to contaminated land.
In the 2000s MfE moved from producing industry-specific guidance to producing a series of Contaminated Land Management Guidelines (CLMG), the first on reporting in 2001, and the second in 2003, being a hierarchy and database of guideline values from overseas, in an attempt to get greater consistency and recognising that New Zealand was never going to produce its own SGV values for many substances. New Zealand then typically looked to the Netherlands, the United Kingdom, Canada, the United States and Australia for SGVs, but the various values were typically quite different across jurisdictions. Two further CLMGs were published in 2004, No. 3 setting out a risk screening system and, arguably the most important, No. 5 setting out the framework for site investigation. The final CLMG to be published, No. 4, is a site classification and information management protocol for councils. Importantly, CLMG 4 contained the first version of the Hazardous Activities and Industries List (HAIL), a key part of the subsequent National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health (the NESCS).
Where we are now?
The late 2000s saw the government increasingly concerned about inconsistency in contaminated land assessment, with only a few councils having specific contaminated land provisions in their district plans. After a period of consultation, in late 2011, regulations under the RMA were issued (the NESCS). A statutory SGV derivation methodology was developed, a suite of soil contaminants standards (SCS) were derived for “priority contaminants” and CLMGs 1, 2 and 5, and the HAIL became statutory documents. Four activities became regulated for HAIL sites; soil sampling, disturbing soil, changing site use, and subdivision. Removal of underground petroleum storage systems was also regulated. The NESCS replaced any contaminated land provisions affecting human health in district plans.
The NESCS certainly brought greater rigour to contaminated land investigation and assessment, but a lack of expertise meant smaller councils, in particular, struggled with its application. The HAIL, essential for determining whether the regulations applied to a particular site, was not originally developed with regulations in mind. Ambiguities in, and misinterpretation of, the HAIL meant many sites were unnecessarily investigated, and the over-cautious soil disturbance provisions imposed unnecessary costs on land development.
The NESCS was to be reviewed after five years, but the clean-up following the Christchurch earthquakes triggered an early review and amendments have been proposed. With the change of government, the amendments have been given a lower priority, and it would seem a revised NESCS will not be implemented until at least 2019. However, it is hoped that issuing revised CLMGs 1 and 5, and HAIL guidance later this year will bring greater consistency. The recent release of New Zealand-specific guidance for asbestos in soil should improve risk-based assessment of asbestos affected sites and hopefully reduce the need for expensive clean-ups. For the future, improved science around bioavailability of some contaminants in soil should allow improved site-specific assessment and reduced remediation costs, but will have to await the NESCS amendments.
The role of WasteMINZ
Throughout the last 25 years, WasteMINZ has provided a forum for central and local government, industry and practitioners to share knowledge and come up to speed with new guidance and regulations. The first contaminated land sessions at the WasteMINZ annual conference occurred as early as 1993, with the first contaminated land workshop at the 1995 conference. The contaminated land sector group was formed in 2006, and the first purely contaminated land stream at the conference was in 2008 and has been a regular feature ever since. The coming of the NESCS was the signal for many workshops aimed at bringing regulators and practitioners up to speed; there have been workshops every year since the NESCS was implemented, including on bioavailability and asbestos in soil. A particularly important initiative supported by WasteMINZ was the formation of a working group of senior practitioners with the task of defining what a suitably qualified and experienced practitioner was, and approaching the CEnvP organisation to develop a specialised contaminated land CEnvP certification. This came to fruition in 2015, and there are now around 30 New Zealand CEnvP(SC) certified practitioners. WasteMINZ continues to be a driving force for the exchange of information and improvement of contaminated land practice in New Zealand.
About the author: Graeme Proffitt is a technical director – contaminated land with Pattle Delamore Partners Limited, where he has worked for nearly 25 years in environmental consultancy. For much of that time, he has assisted central government to develop contaminated land guidelines and regulations.