Publications

Technical reports

Technical Report 47: Australian case studies of light non-aqueous phase liquid (LNAPL) natural source zone depletion rates compared with conventional active recovery efforts

Natural rates of mass loss and biodegradation of light non-aqueous phase liquid (LNAPL) fuels and oils in soil and groundwater is termed natural source zone depletion (NSZD). This report provides detailed, Australia-specific measurements and case studies for six Australian sites and multiple LNAPL product types.

It includes estimates at these sites of NSZD rates for a range of LNAPLs including crude oil, diesel, jet fuel and gas condensate (predominantly gasoline range). The NSZD rates are compared to the most representative active product recovery rates from each of these sites to provide context to the scale of the NSZD rates. Overall the case studies investigated here support the growing body of evidence that in many instances, especially at mature LNAPL sites, LNAPL mass removal through NSZD processes exceeds those achieved through active remediation efforts.

This report complements the LNAPL NSZD application guidance document The role of natural source zone depletion in the management of light non-aqueous phase liquid (LNAPL) contaminated sites (Technical report 46, CRC CARE 2020) and the LNAPL NSZD measurement guidance document Technical measurement guidance for LNAPL natural source zone depletion (Technical report 44, CRC CARE 2018).

Technical Report 46: The role of natural source zone depletion in the management of light non-aqueous phase liquid contaminated sites

This report discusses a growing body of research showing that natural source zone depletion (NSZD) is ubiquitous at light non-aqueous phase liquid (LNAPL) sites. NSZD processes occur at all LNAPL sites to some degree and understanding, quantifying and evaluating their effectiveness is therefore an important part of a sustainable remedial strategy. Accordingly, the potential significance of NSZD at Australian sites has implications with respect to the development of LNAPL conceptual site models and remedial/management strategies.

The assessment of NSZD and use of NSZD data can be considered at different points in LNAPL site management including during:

  • development of the LNAPL conceptual site model
  • assessment of remedial/management options
  • implementation of the remediation/management strategy.

Case studies are presented that provide a number of insights regarding NSZD in general and NSZD at Australian sites specifically. The case studies add to the growing body of evidence that NSZD rates observed at Australian sites are comparable or exceed what is considered typical overseas. Additionally, the case studies indicate that NSZD was found to be substantially outperforming conventional active LNAPL recovery performance at all sites where the comparison was possible (i.e. where active LNAPL recovery efforts were taking place).

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Technical Report 45: Societal perceptions on remediation technologies: guidance for engagement with residents

Remediation policies and guidelines are increasingly recognising the value of drawing on the knowledge and experiences of diverse stakeholders, including affected residents, to support technology selection, and to inform other related areas of remediation policy such as risk management and sustainability assessment. This report helps remediation service providers, auditors, local governments, health professionals and environmental regulators to develop and implement plans for remediation using an evidence-based understanding of residents’ perceptions and acceptance of remediation technologies.

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Technical Report 44: Technical measurement guidance for LNAPL natural source zone depletion

Natural source zone depletion (NSZD) is a term used to extend the traditional understanding of natural attenuation to the light non-aqueous phase liquid (LNAPL) source zone. It describes the collective, naturally occurring processes of dissolution, volatilisation, and biodegradation that result in mass losses of LNAPL petroleum hydrocarbon constituents from the subsurface. This document provides practical guidance on the measurement of NSZD rates using various available methods. The report provides a knowledge base and procedures for consistency in the measurement of NSZD in Australia, and captures the state of the practice and is useful as a guide to develop site-specific plans.

The methods for measurement of NSZD rates include:

  • Aqueous methods using dissolved contaminant concentration trends and natural attenuation indicator parameter (NAIP) mass budgeting analysis
  • Soil gas flux methods using concentration gradients, passive flux traps, and thedynamic closed chamber (DCC)
  • Biogenic heat method based on soil temperatures
  • LNAPL compositional change method based on chemical analysis of the oil.

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Technical Report 43: Practitioner guide to risk-based assessment, remediation and management of PFAS site contamination

This practitioner guide deals with PFOS and PFOA given their known physical and chemical properties, toxicity, and behaviour, fate and transport in the environment. These factors are considered in terms of their relevance to risk-based site contamination. The guide also provides an overview of the application of Australian approaches, which in turn provides the background for site-specific risk assessments, as well as the basis for the development and application of screening levels. It is a technical resource for the application of risk-based approaches to the assessment, remediation and management of PFAS site contamination.

This guide complements the National Environment Protection (Assessment of Site Contamination) Measure 1999 (ASC NEPM) and the PFAS National Environmental Management Plan (NEMP). Released by the Heads of EPAs Australia and New Zealand in February 2018, the NEMP is the key reference document for PFAS in Australia and covers a range of matters relevant to the identification and management of PFAS from the perspective of regulators. This practitioner guide is compatible with those requirements of the ASC NEPM that flow through to remediation. It is designed to also be consistent with the National Remediation Framework currently being developed by CRC CARE.

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Technical Report 42: A human health review of PFOS and PFOA

PFOS and PFOA have been identified as contaminants of emerging concern in Australia. Both chemicals are persistent, bioaccumulative and potentially toxic, and exist at a number of sites, particularly where AFFF firefighting foams have been used. Originally, this report was developed to recommend tolerable daily intake (TDI) values for PFOS and PFOA, at a time when there were no national TDI values available (early 2016). The report provides an overview of the international studies used in considering TDI values. It also recommends background intake levels for PFOS and PFOA in Australia, which may be useful when assessing multiple exposure pathways.This version of the report does not recommend TDIs, and has been published for information only.

The report refers to data from animal studies to estimate effects on human health in order to derive TDI values – while this introduces interspecies uncertainties, animal models exclude human variability factors (such as diet, drugs, infections, radiation and endogenous processes). An in-depth discussion of the issues was published as a peer-reviewed paper – see Dong et al 2017, ‘Issues raised by the reference doses for perfluorooctane sulfonate and perfluorooctanoic acid’, Environment International 105: 86-94.

This report was completed in early 2016 to complement CRC CARE’s work on developing PFAS guidance at a time when there was limited Australian human health advice on PFAS.  The policy, scientific and political landscape has changed substantially several times since this work was completed, and it is strongly recommended that readers refer to the most up-to-date advice published by Food Standards Australia New Zealand and the Commonwealth Department of Health, as well as any jurisdictional requirements.

An in-depth discussion of the issues was published as a peer-reviewed paper – see Dong, et al 2017. ‘Issues raised by the reference doses for perfluorooctane sulfonate and perfluorooctanoic acid’ Environment International 105: 86-94.
Technical Report 41: Remediating and managing coastal acid sulfate soils using Lime Assisted Tidal Exchange (LATE) at East Trinity, Queensland

This report reviews the implementation and associated research activities of a successful coastal acid sulfate soil (CASS) remediation strategy. East Trinity is a case study of how a severely degraded tidal wetland has been returned to a functional estuarine habitat using a cost-effective, low technology method based on the reintroduction of tidal water. The East Trinity experience is a reference point for best-practice remediation and management of broadacre CASS and is an exemplar conversion site linked to the National Standards for Ecological Restoration.

The remediation strategy known as lime assisted tidal exchange (LATE) was implemented in 2001 following a comprehensive site and operational methodology assessment. An initial trial of LATE proved successful in terms of the water quality and soil parameters. The short time period in which these parameters responded prompted the need for a research program aimed at understanding the interaction of daily tidal inundation and an acidified soil landscape. This research showed that LATE’s success can be attributed to the combination of an alkaline input alongside a huge flush of organic matter. The East Trinity site now has sufficiently high ecological function to transition from active to passive management. Under passive management, the addition of hydrated lime to the waterways ceases, and regular tidal inundation will remain in place to ensure that ASS remain protected from further oxidation.

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Technical Report 40: Weathered Petroleum Hydrocarbons (Silica Gel Clean-up)

This technical report has been prepared to review the available information on the presence of polar metabolite compounds in samples collected from weathered petroleum hydrocarbon–impacted soil and groundwater. The aim is to identify an appropriate silica gel clean up (SGC) method for removing these compounds from the analysis of petroleum hydrocarbons, and to provide guidance on interpretation of the data collected, to ensure that risks to human health and the environment are adequately protected.

Analytical methodology for silica gel clean-up of soil and water extracts is proposed in this report. The methodology follows closely with NEPM Schedule B3 (NEPC, 1999 amended 2013c), that is analysis of semi-volatile hydrocarbons (TRH >C10 to C40) using solvent extraction followed by determination by gas chromatography–flame ionisation detector (GC-FID). The NEPM describes an optional SGC procedure but more detail is required. Appendix C details two procedures for SGC which are in common use in environmental testing laboratories – in situ and ex situ. These procedures have been adapted from CCME 2001, Reference Method for the Canada-Wide Standard for Petroleum Hydrocarbons in Soil – Tier 1 Method, and Addendum 1. The in-situ method involves adding silica to the extract to form a ‘slurry’. This silica then interacts and absorbs polar analytes. In the ex-situ method, the extract is applied to a silica gel glass column which removes polars from the extract. The extracts are then analysed by GC-FID. Advantages and disadvantages of both techniques are discussed in this report.

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Technical Report 39: Risk-based remediation and management guidance for benzo(a)pyrene

This report provides guidance on the risk-based management and remediation of benzo(a)pyrene (B(a)P)-contaminated sites. It provides information and a framework that will assist practitioners, regulators and site owners in effectively managing and remediating B(a)P-contaminated soil and groundwater.

In particular, the guidance has the potential to promote best practice and reduce costs, uncertainty, and the risk to human health and the environment. Consideration has been given to accounting for site-specific variables such as bioavailability and bioaccumulation, and for providing more reliable screening criteria for determining when ecological effects might occur.

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Technical Report 37: Flux-based groundwater assessment and management

In line with international progress, there has been an increasing acceptance in recent years by contaminated sites practitioners in Australia of the usefulness of mass flux concepts for the management of groundwater contamination. However, there is no nationally consistent guidance or methodology on how mass flux or mass discharge estimates may be used to assess and manage groundwater contamination, or the endpoints that should apply. CRC CARE has therefore commissioned this user guide for the better measurement and use of mass flux and mass discharge in the management of groundwater contamination.

The purpose of this guidance is therefore to illustrate how flux concepts, tools and measurements can be used to assess and manage groundwater contamination, including engaging with regulators and other stakeholders.

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Technical Report 36: Guidance for the assessment, remediation and management of MTBE

This document provides guidance in relation to the assessment, remediation and management of MTBE contaminated groundwater. MTBE will migrate rapidly from a source, through the soil profile, to groundwater and/or surface water. MTBE is degraded rapidly in surface waters, but it is relatively stable in groundwater. Once MTBE reaches groundwater it can migrate at almost the same speed as groundwater flow, given its solubility in water, and therefore can travel rapidly in the sub-surface.

This document provides guidance in relation to the assessment, remediation and management of MTBE contaminated groundwater. MTBE will migrate rapidly from a source, through the soil profile, to groundwater and/or surface water. MTBE is
degraded rapidly in surface waters, but it is relatively stable in groundwater. Once MTBE reaches groundwater it can migrate at almost the same speed as groundwater flow, given its solubility in water, and therefore can travel rapidly in the sub-surface.

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Technical Report 35: Value-based land remediation: Improved decision-making for contaminated land

This report provides regulators and remediation professionals with a summary of research into how remediation institutions interact with the values held by various stakeholders, as reflected in site remediation decision-making processes, and hence the outcomes of these decision processes. Using case studies (three from Australia, one from Fiji), it highlights how the findings might be incorporated into current and future site remediation practice.

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Technical Report 34: A practitioner’s guide for the analysis, management and remediation of LNAPL

This report is intended as a practical guide to LNAPL remediation in Australia and to accompany CRC CARE Technical Report no. 18, Selecting and assessing strategies for remediating LNAPL in soils and aquifers.

This guide draws on the wealth of literature on LNAPL remediation globally, and on the documented experience of remediation practitioners in Australia, Europe and North America, where many of the approaches, terms and technologies discussed in this document have been developed.

It is aimed at industry project managers, environmental consultants, remediation practitioners, owners and operators of contaminated sites, and state and territory regulators in Australia – that is, those with an interest in the effective, efficient and sustainable remediation of LNAPL contaminated sites. The guide provides a practical step-by-step approach to site characterisation, remedial decision making, technology selection and implementation of remediation in an Australian context.

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Technical Report 33: Advanced Lidar Port Hedland dust study

This study confirmed that a Coherent Doppler Lidar system for monitoring dust emissions and wind fields can be used to identify dust emission sources, track dust plumes, and resolve the fine-scale wind field dynamics responsible for dust transportation and community exposure. The technology can potentially be used for multiple applications at ports and mine sites, including routine monitoring, health risk and occupational safety studies, validation of modelling, and evaluating dust mitigation strategies.

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Technical Report 32: Development of guidance for contaminants of emerging concern

Emerging contaminants are a concern for contaminated site assessment, management and remediation. The first tier priority contaminants that were identified at a February 2012 forum were perfluorinated chemicals PFOS and PFOA, methyl tertiary-butyl ether (MTBE), benzo[a]pyrene (BaP), weathered hydrocarbons and polybrominated diphenyl ethers (PBDE).

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Technical Report 31: Flux-based criteria for management of groundwater

This report reviews guidance, documents, tools and industry practice relating to the application of mass flux-based criteria for the management of groundwater contamination. It aims to determine where further work should be carried out to realise the advantages of mass flux-based assessment of groundwater contamination, and to identify the most reliable and promising methods for further research and application.

This report reviews guidance, documents, tools and industry practice relating to the application of mass flux-based criteria for the management of groundwater contamination. It aims to determine where further work should be carried out to realise the advantages of mass flux-based assessment of groundwater contamination, and to identify the most reliable and promising methods for further research and application.

This report has a focus on Australian regulations and practice; however, similar approaches to the assessment and management of contaminated groundwater are applied internationally and the findings and recommendations of this report can be expected to have general applicability.

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Technical Report 30: Landfill futures

This report looks at the past and present roles of landfills in Australian waste management and considers the requirements for a sustainable future. The research used a test case to apply an integrated resource planning model to waste. The results suggest that disposal to landfill may be an expensive and less preferred option compared to others, in many cases, but still have a role to play in specific contexts where the costs of other options are higher.

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Technical Report 29: Environmental impact of priority contaminants - A literature review

In order to identify emergent and priority contaminants and to prioritise work on them, CRC CARE conducted a workshop in February 2012 with regulators and end users. The outcomes of the workshop, together with information from a matrix pre-population exercise prior to the workshop, have resulted in a list of contaminants classified in three categories: ‘first-tier priority’, ‘second-tier priority’ and ‘watching brief’. The table below summarises the outcomes in relation to contaminants in the first-tier category. The aim of this project was to undertake a literature review on these first-tier priority contaminants in order to identify data gaps (e.g. toxicity, remediation technologies) for future CRC CARE research programs. This information is viewed as critical for all research programs within CRC CARE and is paramount for the development of guidance for these stakeholder prioritised contaminants.

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Technical Report 28: Identification of existing guidance for a National Remediation Framework

In 2011 CRC CARE established the National Remediation Framework Steering Group (NRFSG) comprising high level representatives from government, industry, academia, and the community to provide strategic advice and oversee the development of the National Remediation Framework (NRF).

The Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) is Australia’s leading science-based partnership in assessing, preventing and remediating contamination of soil, water and air.
Currently, CRC CARE is developing a national framework for the remediation of contaminated sites in Australia. In 2011 CRC CARE established the National Remediation Framework Steering Group (NRFSG) comprising high level representatives from government, industry, academia, and the community to provide strategic advice and oversee the development of the National Remediation Framework (NRF).

In developing the framework CRC CARE wishes to build upon what is already available, with the aim of developing a ‘harmonised guidance on the practicalities of cleaning up contaminated sites’. To that end, CRC CARE has developed a number of projects to identify existing frameworks and guidance that may be incorporated into the NRF.
This project is part of the second phase of development, with the objectives of:

  • identifying existing guidance on site remediation (Australian and international) that may be suitable for adoption or adaption into the NRF
  • reviewing the guidance to assess whether it meets the needs of the proposed framework, and provide recommendations for adoption/adaption, focusing on the following areas:
  • development of remediation and management plans
  • implementation of remediation plans
  • post remediation considerations, and
  • conducting a data gap assessment to determine whether

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Technical Report 27: Defining the philosophy, context and principles of the National Framework for remediation and management of contaminated sites in Australia

This project is the first of the two projects in the second stage of the development of the National Framework for Remediation and Management of Contaminated Sites in Australia (the Framework) and entailed work on the philosophy, context and principles sections.

The project used background information gained from the report Review of Australian and international framework (Scott & McInerney 2012), and considered current regulation, policy and principles in each of the jurisdictions, as well as input from the NRFSG.

It was also an imperative with the NRFSG that in developing the framework, harmonisation of approaches related only to philosophy and practice, not legislation.

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Technical Report 26: Phosphorus management in soils using coal combustion products

Large quantities of coal combustion products (CCPs) are being generated worldwide annually and dumped in large piles as landfills. These products are residues from the combustion of coal, largely used for electricity generation. The economic availability of coal and the burgeoning demands of the rising population are set to increase the coal-fuelled electricity generation in the future. Australia, being amongst the top nations in using coal for production of electricity, generates enormous quantities of CCPs. There is an increasing concern among the power stations and environmental agencies on the mobility of heavy metals from the CCPs, which may result in contaminating our land resources and water bodies.

Large quantities of coal combustion products (CCPs) are being generated worldwide annually and dumped in large piles as landfills. These products are residues from the combustion of coal, largely used for electricity generation. The economic availability of coal and the burgeoning demands of the rising population are set to increase the coal-fuelled electricity generation in the future. Australia, being amongst the top nations in using coal for production of electricity, generates enormous quantities of CCPs. There is an increasing concern among the power stations and environmental agencies on the mobility of heavy metals from the CCPs, which may result in contaminating our land resources and water bodies.

Although the coal-fired power generation has evolved a long way towards clean coal processing technologies, resulting in higher energy production and value addition, there has not been any breakthrough in reducing the volume of combustion wastes i.e., the CCPs generated. Consequently, the ash dumps are fast inflating and envisaged for more expansion in the impending years. This is mainly due to the under-utilisation of these waste materials in some countries, where the concerns towards environmental health and public well-being had not been addressed. The possible uses of CCPs in the construction industry as a cement substitute; in agriculture as a liming agent; and in environmental remediation have reaped benefits round the globe. Current utilisation levels of these resources in Australia are low, considering their actual potential in environmental remediation.

Most Australian soils are inherently deficient in phosphorus (P) and many sandy soils are not efficient in the retention of P, thereby results in leaching and (surface) runoff losses. Agricultural application of fertilizer P and wastes including farm effluents, manures and biosolids (BS) have been the most significant contributors of P build-up in soils and consequent accumulation in water bodies causing eutrophication. The immobilisation of P in soils using CCPs has been a significant area of research over the past decade not only for the potential of CCPs in minimising the loss of P, but also making the P bioavailable for agronomic utilisation.

Transformation [(im)mobilisation] of P in soil is closely associated with the pH and the concentrations of iron (Fe), aluminium (Al) and calcium (Ca) in the soil. An increase in soil pH generally increases the potential of inorganic P immobilisation in soil via P adsorption, especially to acidic and neutral soils. However, Ca concentration also influences adsorption of P. At very high pH and high Ca concentration, inorganic P gets precipitated with Ca and it becomes strongly immobile. However, at low pH, P adsorbs to the surface of Fe and Al oxides. The pH also influences the breakdown of organic P into inorganic P in soil, due to phosphatase activity and the resultant P mineralisation. The CCPs are generally alkaline and are rich in these cations and hence can serve as potential amendments for P management in soil, which will be explained in this report using immobilisation, transformation and bioavailability experiments. Also, this report will serve as an effective guide for the farming communities and a source of information for industries and researchers related to CCPs.

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Technical Report 25: A framework for selecting, designing and implementing a permeable reactive barrier system

This report addresses the use of permeable reactive barriers (PRBs) at contaminated sites. It includes guidance on suitability assessment, design, operation, monitoring and decommissioning while taking into consideration existing international guidance, protocols and research.

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Technical Report 24: Analytical methods for priority and emerging contaminants - a literature review

The availability of analytical methodology with sufficient detection sensitivity and selectivity is crucial to effective management of environmental contaminants. This review has considered the analytical methodology available for a range of Contaminants of Emerging Concern (CECs) and assessed the measurement-related needs on the basis of two key criteria: the relevance of each contaminant to the Australian environment and the degree to which appropriate analytical capability is available in Australia. Quality assurance tools essential for ensuring comparability of results between laboratories, such as availability of proficiency testing (PT) studies and reference materials were also considered.

The availability of analytical methodology with sufficient detection sensitivity and selectivity is crucial to effective management of environmental contaminants. This review has considered the analytical methodology available for a range of Contaminants of Emerging Concern (CECs) and assessed the measurement-related needs on the basis of two key criteria: the relevance of each contaminant to the Australian environment and the degree to which appropriate analytical capability is available in Australia. Quality assurance tools essential for ensuring comparability of results between laboratories, such as availability of proficiency testing (PT) studies and reference materials were also considered.

The first task of this project was to develop a shortlist of contaminants for detailed investigation using a combination of CRC CARE end-user input and international peer-reviewed literature. The former included the findings of a CEC Forum held by the CRC in February 2012 which generated a ‘first tier priority’ list of contaminants (Priority 1: methyl tertiary butyl ether (MTBE), perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), weathered hydrocarbons, benzo(a)pyrene (BaP) and polybrominated diphenyl ethers (PBDEs)). Another four classes of contaminants determined from the literature and discussions with Australian and international experts to be important emerging contaminants were selected for review as Priority 2. These were perfluorinated alkyl substances (PFASs) other than PFOS and PFOA, novel flame retardants (FRs), short-chain chlorinated paraffins (SCCPs) and methylsiloxanes. Other contaminants nominated by CRC CARE end-users or found in literature reports were selected as Priority 3, requiring further investigation regarding their relevance in the Australian remediation context, based on their likely use and environmental prevalence. The Priority 3 contaminants were 1,4-dioxane, benzotriazoles, ionic liquids, benzidine dyes, musk fragrances, microbicides, organoboron, organoplatinum, arsenic species and nanoparticles.

The project team then undertook a more detailed literature review into each of the Priority 1, Priority 2 and Priority 3 contaminants. As part of the review, a voluntary and anonymous survey of NATA-accredited laboratories was also conducted to assess the availability of analytical capabilities in Australia.

The key findings of the review were that:

  • Significant analytical methodology gaps were not found for any of the Priority 1 compounds, although tools to assess laboratory performance such as easily accessible proficiency testing (PT) schemes are lacking. This may seem surprising in view of their identification by the CEC Forum as a ‘first tier priority’. It should be noted, however, that the research requirements specified by that Forum were much more wide-ranging than the analytical methodology focus of this review and that in the cases of MTBE and BaP, the research needs identified by the Forum were explicitly focussed on areas other than measurement. In addition, there has already been considerable research into all the Priority 1 compounds in recent years, which has in turn resulted in substantial progress in analytical method development for these compounds.
  • Analytical capability gaps in Australia were identified for SCCPs, PFASs other than PFOS and PFOA, novel FRs other than PBDEs, synthetic musks, benzidine dyes, benzotriazoles, methylsiloxanes, organoplatinum compounds and nanomaterials. There appear to be suitable methods in the literature for PFOS, PFOA, PBDEs, novel FRs including tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCDD), and synthetic musks. Development of local analytical capability for SCCPs, PFSAs and selected FRs including TBBPA and HBCDD appears to present the most significant priority for Australia given the relatively high level of usage in this country.
  • Gaps in the availability of matrix reference materials in areas where analytical capability exists or where it has been recommended were identified for PFASs including PFOS and PFOA, SCCPs, TBBPA and HBCDD, benzotriazoles, synthetic musks and arsenic species.
  • Gaps in the availability of proficiency testing studies by Australian providers in areas where analytical capability exists or where development has been strongly recommended were identified for MTBE, PAHs including BaP, PFASs including PFOS and PFOA, PBDEs, arsenic species, SCCPs, HBCDD and TBBPA.

The recommendations from the review were that:

  • For the very diverse groups of PFASs and novel FRs, especially TBBPA and HBCDD, analytical methodology is not adequate in Australia. Many of these compounds will be used in Australia as they have important commercial applications, and many are subject to long-range transport and may be found in the Australian environment whether they are used here or not. Further investigation into which analytes will be most significant for the Australian environment is recommended. The development of methods, production of reference materials and coordination of PT schemes can then be considered for the more relevant analytes.
  • The development of methods, production of reference materials and coordination of PT schemes for short-chain chlorinated paraffins (SCCPs) is strongly recommended.
  • The development of analytical methods for benzotriazoles and synthetic musks is recommended, to allow the distribution and environmental impact of these contaminants in Australia to be assessed.
  • The production of reference materials and coordination of PT schemes for arsenic species in environmental matrices is strongly recommended.
  • Activities of interest would be the development of methodology to allow studies to be conducted into the extent of contamination by methylsiloxanes, benzidines arising from dyestuffs and organoplatinum anticancer drugs.

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Technical Report 23: Petroleum hydrocarbon vapour intrusion assessment - Australian guidance

This document provides a clear decision framework for the conduct of petroleum vapour intrusion assessments resulting from contamination of soil and groundwater by petroleum hydrocarbons.

This document provides a clear decision framework for the conduct of petroleum vapour intrusion assessments resulting from contamination of soil and groundwater by petroleum hydrocarbons.

Drawing on the best available guidance and science relating to the current understanding of petroleum vapour intrusion from Australia and other jurisdictions, this document outlines approaches that should be considered in the assessment of acute and chronic risks. These approaches may be on the basis of either an initial screening or a more detailed assessment as appropriate.

This decision framework incorporates flow diagrams and “decision boxes”, with additional detail provided in appendices. It is expected that this decision framework will assist the user in making appropriate and sound decisions in the assessment of petroleum vapour intrusion, including the collection and evaluation of vapour data.

The potential for petroleum vapour intrusion may vary considerably with different situations, as petroleum hydrocarbons readily biodegrade in the subsurface when sufficient oxygen is available, and this guidance provides the means to take such variability into account.

While several aspects of this guidance are general and can be applied to a range of volatile compounds, the guidance is intended to specifically address petroleum vapour intrusion, and should not be applied to sites contaminated with other compounds not sourced from petroleum, such as chlorinated hydrocarbons and landfill gas.

While the decision framework and the methods and approaches listed or presented in the guidance are specifically oriented towards assessment of petroleum vapours, this does not mean that methods and approaches not presented in the guidance cannot be utilised. Rather, other approaches can be used, where relevant, and adequately justified and agreed with regulators, auditors or third party reviewers prior to use.

By following the guidelines outlined in this document, the assessment of petroleum vapour intrusion will be adequately robust and will meet regulatory (and auditor/third party reviewer) requirements for the completion of such assessments.

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Technical Report 22: Developing a national guidance framework for Australian remediation and management of site contamination - Review of Australian and international frameworks for remediation

This project is the first of several projects required to deliver an accepted national remediation framework (NRF) and guidance.

The Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) carries out research into the assessment and clean-up of contaminated sites. During the preparation of its successful bid for funding to 2020, the need for a nationally consistent approach to remediation of contaminated sites was identified by:

  • representatives of environmental regulatory bodies from across Australia
  • major corporate entities which operate and clean-up sites across multiple jurisdictions.

It was acknowledged that current guidance for the remediation and management of contaminated sites comprises some high quality, but dated, national documents, and high quality, but non-harmonised, guidance issued by some jurisdictions. Early discussions regarding the purpose, benefits and limitations of a new remediation framework identified the following elements as important in the consideration of the approach, structure and content of the document – the framework should:

  • enable a nationally consistent approach to remediation of contaminated sites
  • be established under the umbrella of the Standing Council on Environment and Water (SCEW)
  • NOT impinge on the policy and decision-making prerogatives of the states and territories
  • NOT be legally binding
  • distil and utilise existing documentation and experience, and
  • provide practical guidance within an overall framework which establishes the context for remediation in Australia.

 

This project

This project is the first of several projects required to deliver an accepted national remediation framework (NRF) and guidance. It is essentially an initial and exploratory scan of national and international sources in order to identify:

  • international remediation and management frameworks which may be suitable for adoption or adaption in an Australian context
  • current regulation of remediation and management of site contamination in Australia, and
  • barriers to the adoption of an Australian NRF and management of contaminated sites.

The focus of the project was the gathering of information that may assist the national remediation framework steering group (NRFSG) as it considers:

  • effective ways to approach the development of the framework in the Australian regulatory context
  • the potential structure of the framework and the areas to be covered within the framework, and
  • content to be included in the framework.

Information was gathered regarding frameworks that are used to guide the remediation and management of contaminated sites in a number of international jurisdictions. Information was also gathered regarding general approaches taken to remediation and management in the six states and two territories of Australia. Some national documents, approaches and processes for dealing with assessment of contaminated sites were also considered for their potential for adaptation to a management and remediation context.

A number of common elements exist in the structure and content of framework documents scanned for this project. There is also commonality in the way that remediation and management of contaminated sites is approached generally in jurisdictions in Australia and internationally.

In order to synthesise the information gathered in this project in a useful way, an example framework has been provided, including possible elements of a framework document. The particular priorities, requirements and content for the Australian national remediation and management framework will, of course, be developed over the coming years.

The example framework is offered simply as a tool to summarise the elements common to remediation and management as found in this scanning project, and to organise, in framework style, some of the elements and issues that could be addressed as part of the harmonisation process. In summary, the example framework comprises two distinct parts which are themselves comprised of particular elements as briefly described as follows:

Part 1: Philosophy

  • Context

–      includes background and jurisdictional arrangements, as well as the purpose and intended audience for any framework documentation

  • Policy and principles

–      includes discussion of agreed principles and policy approaches that do or will guide activities related to remediation and management, e.g. precautionary principle, liability, risk management, green remediation

Part 2: Practice

  • Guidance

–      includes practical guidance for practitioners, provided either as specific advice or techniques outlined within the text of the framework document, or as references to tools and guidance available elsewhere.

Guidance could relate to all steps of the remediation and management process from the setting of remediation objectives to post-remediation auditing and the use of institutional controls.

A full description of the example framework is provided in Section B of this report.

 

Addressing barriers to a national approach on remediation and management

Barriers to a national approach toward remediation and management of contaminated sites are most likely to arise from the lack of an existing legislative and regulatory framework through which such matters can be addressed. Unlike the development of the National Environment Protection (Assessment of Site Contamination) Measure (NEPM), which provides a framework for the assessment of contaminated sites and was undertaken using processes established under law, the development of a national remediation and management framework is not provided for in existing legislation.

The Australian experience in developing a national approach to the assessment of contaminated sites does demonstrate the success of cooperative efforts across states and territories in the past. That this cooperation is an ongoing asset has been demonstrated during the recent review and proposed variation of the NEPM. Recent restructuring of the ministerial council system may also assist the process of developing a national framework for remediation and management of contaminated sites.

Following the 2010 review of the ministerial council system by the Council of Australian Governments (COAG), the SCEW Council was established with a number of priorities, the first being to pursue seamless environmental regulation and regulatory practice across jurisdictions.

A seamless environmental regulation thematic oversight group (SERTOG) has
been established to further the Council’s aims, and the development of a national remediation and management framework has been selected as a pilot project. Comprising representatives from jurisdictions across Australia, SERTOG has the potential to be a key resource, given the relationship its members have to regulatory practice in the states and territories. The group’s membership and structure should enable it to become an effective mechanism for the identification, management and resolution of potential paths and barriers to the adoption of a national framework.

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Technical Report 21: Sampling strategies for biological assessment of groundwater ecosystems

The effective management of groundwater resources across Australia is essential to meet current and future national water needs. At the same time, the significance of groundwater ecosystems in terms of their biodiversity and ecosystem services is increasingly being recognised such that surveys of groundwater ecosystems are now often a part of development applications and environmental impact assessments.

The effective management of groundwater resources across Australia is essential
to meet current and future national water needs. At the same time, the significance
of groundwater ecosystems in terms of their biodiversity and ecosystem services is increasingly being recognised such that surveys of groundwater ecosystems are now often a part of development applications and environmental impact assessments.

Despite the growing awareness of the value of groundwater ecosystems, there is currently little guidance available to assist practitioners in their assessment. Accordingly, the aim of this document is to provide guidance on methods and strategies for the biological assessment of groundwater ecosystems, specifically in
the context of localised environmental threats or impacts. Within the context of contaminated site assessment, routine investigation of groundwater ecosystems may not be required, but should be considered in areas of ecological significance or conservation value.

The groundwater environment is characterised by total darkness. As a result, there
are no photosynthetic primary producers and (usually) only low concentrations of organic carbon as an energy source for the ecosystem. The biota of the ecosystem
is comprised of two major components: the microbes (including bacteria and fungi), and the larger mostly crustacean macro- and meiofauna (stygofauna). Accordingly, groundwater ecosystems are very different from surface water ecosystems, and so require different strategies for their biological assessment.

Sampling of stygofauna is generally conducted by means of pumps, nets or traps, with the choice of method often having little impact on the variety of animals collected, but some influence on the abundance of those animals. Importantly, to adequately assess the diversity of stygofauna at a location, multiple bores must be sampled on multiple occasions. Samples from multiple bores on a single occasion, or from a single bore on multiple occasions, will not adequately assess stygofauna diversity. Our sampling indicates that at least five sampling locations and five sampling events may be required.

Microbial assemblages may be assessed by a variety of means including molecular or metabolic fingerprinting, direct measurement of biomass and microbial enzyme activity. Irrespective of the method chosen, repeat temporal and spatial sampling should be undertaken. While measures of microbial activity at relatively undisturbed sites may be variable over time, the effects of disturbance to an aquifer may cause a large and readily detectable shift in microbial activity, greatly exceeding the spatial and temporal variability among undisturbed sites.

Assessments of aquifer ecosystems in the context of environmental impact assessment should examine both microbes and stygofauna, reflecting the major biotic components of the ecosystem. Multiple samples over space and time are necessary, with the exact level of replication and sampling effort ideally determined by site-specific studies.

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Technical Report 20: Guidance document for the revegetation of land contaminated by metal(loid)s

The revegetation of sites contaminated by metals (such as Cu, Zn, Ni, or Pb) and metalloids (such as As) is an important environmental challenge. On a global-scale, large investments are required in order to rehabilitate the soil to a productive and non-environmentally-damaging endpoint, and as a result, an ever increasing number of technologies have been developed.

The revegetation of sites contaminated by metals (such as Cu, Zn, Ni, or Pb) and metalloids (such as As) is an important environmental challenge. On a global-scale, large investments are required in order to rehabilitate the soil to a productive and non-environmentally-damaging endpoint, and as a result, an ever increasing number of technologies have been developed. However, the successful implementation of a revegetation system requires a true multi-disciplinary effort, with collaboration between soil scientists, agronomists, hydrologists, ecotoxicologists, and economists.

The overall revegetation process can be separated into three broad steps:

  1. assessment of soil contamination
  2. remediation, and
  3. revegetation / plant selection.

Although all three steps are considered here, an emphasis is placed on the first and last of these. This document provides a brief review of current knowledge, with a particular emphasis on Australian plants and landscapes.

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Technical Report 19: Winery wastewater irrigation - effects of potassium and sodium on soil structure

Generation of wastewater is an inevitable component of the wine production process. Typically this wastewater has a high salt concentration, due mainly to chemical cleaning products and spent grape lees. Land application of winery wastewater is increasingly being advocated as a means to mitigate deteriorating water quality associated with surface water discharge. A major agricultural concern however, is the potential for monovalent cations, namely sodium (Na+) and potassium (K+) to accumulate in the soil profile and subsequently impact on soil structure.

Generation of wastewater is an inevitable component of the wine production process. Typically this wastewater has a high salt concentration, due mainly to chemical cleaning products and spent grape lees. Land application of winery wastewater is increasingly being advocated as a means to mitigate deteriorating water quality associated with surface water discharge. A major agricultural concern however, is the potential for monovalent cations, namely sodium (Na+) and potassium (K+) to accumulate in the soil profile and subsequently impact on soil structure.

Best management practice for managing nutrients in many wastewaters generally focuses on retaining constituents, such as nitrogen (N) and phosphorus (P), within the soil profile where they are assimilated into plant growth. However, the assimilation of Na+ by plants is low, and the best management approach to mitigate the potential effects of high soil Na+ concentrations is to leach this salt down the soil profile. Plant K+ requirements are generally high (i.e. similar to N), however, high loadings typical under winery wastewater (i.e. 600 kg K+ ha-1 yr-1) far exceed plant requirements. Although the relative effect of K+ on soil structure is less than that of Na+, an excess in the soil profile can contribute to a decline soil structure.

In many regions, Na+ and K+ are readily leached during winter rainfall events and, therefore, pose limited risk of accumulation or subsequent soil dispersion. In fine-textured soils that tend to drain poorly, or where loading rates of constituents are high, achieving adequate leaching may be problematic. A greater degree of management will, therefore, be required at locations where winery wastewater is applied to fine- textured soils with high clay content. Where accumulation of salts is likely, maintaining a sodium adsorption ratio (SAR) of winery wastewater below 6 (mmolc L-1)0.5 and potassium adsorption ratio (PAR) below 10 (mmolc L-1)0.5 is likely to prevent adverse soil structural changes.

There is a close relationship between winery wastewater electrical conductivity (EC) and soil dispersion, whereby adverse changes to soil structure under high net loading of Na+ or K+  is mitigated at higher EC. It is therefore valuable to include measurement of winery wastewater EC in routine analysis. Routine use of calcium (Ca2+) amendments including, yet not restricted to, lime, gypsum and calcium nitrate – either added directly to wastewater or to soils – will enable Ca2+ exchange and displacement of Na+ and K+. Winter application of Ca2+ amendments will ensure its percolation down the soil profile, thereby ensuring good distribution of Ca2+ and raising soil EC that is otherwise lowered under rainfall.

Given the lesser effect of K+ on soil structure relative to Na+, a switch to potassium-based sterilisers will lower SAR in the final stream. In addition to this, the greater PAR in winery wastewater will further prevent Na+ retention in soils.

The greatest volume of winery wastewater is generated immediately after vintage, during which time salt concentration tends to be at a maximum. The quantity of salt applied to soils with irrigation is influenced by the land area over which it is distributed. Because the period that winery wastewater is applied to land is relatively short, i.e. immediately following vintage, greater land area will be an effective means of minimising the net salt accumulation in soils. To avoid nutrient imbalances in crops grown with winery wastewater, loading rates could be determined based on meeting the K+ demand of the crop. With adequate management (namely, prevention of high ESP and EPP during consecutive seasons) the risk of soil dispersion can be mitigated.

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Technical Report 18: Selecting and assessing strategies for remediating LNAPL in soils and aquifers

Light non-aqueous phase liquid (LNAPL) petroleum hydrocarbons are complex mixtures of chemicals that variably partition into water and gaseous phases when released into subsurface environments. They pose a range of concerns – from issues of aesthetics and nuisance to acute risks to human health and the environment.

Light non-aqueous phase liquid (LNAPL) petroleum hydrocarbons are complex mixtures of chemicals that variably partition into water and gaseous phases when released into subsurface environments. They pose a range of concerns – from issues of aesthetics and nuisance to acute risks to human health and the environment. The properties of LNAPL and its interaction with geological strata make effective removal of LNAPL contaminants difficult. Indeed, effective remediation and amelioration of concerns may not be possible in many situations. In addition, much uncertainty arises through an incomplete understanding of the potential effectiveness of LNAPL remediation strategies in different subsurface settings.

Major challenges in addressing LNAPL contamination include:

  • knowing enough about likely LNAPL behaviour in subsurface environments
  • building an adequate LNAPL conceptual site model
  • adequately assessing all concerns posed by LNAPL at a site
  • defining technology and site end points
  • balancing the need for action at a site with achievable end points
  • overcoming the lack of information on the field-scale effectiveness of remediation technologies in different settings
  • matching the capability of remediation technologies to desired remediation end points for a site
  • having adequate measures to quantify the performance of remediation technologies
  • knowing when and if remediation technologies reach their practicability limits
  • determining the net environmental and social benefits of LNAPL remediation.

This report seeks to provide information and a framework that would allow some of these challenges to be addressed. It provides guidance in selecting and matching the performance of remediation technologies to a range of subsurface settings, risk reduction targets and concerns. The emphasis here is on LNAPL that has infiltrated to the water table and in settings of major relevance to Australia. One of the aims is to identify the gaps in the current understanding of remediation process and performance in the various subsurface settings. Not all the information required is available or known. As such, this document provides a status report, which can be updated as research and additional experience fills the identified gaps.

We examine existing (and some past) approaches to LNAPL remediation in Australia and internationally. In the context of risk-based remediation, the process of identifying concerns (including risks) that may trigger LNAPL remediation is described. It is then shown how the identified concerns are used to formulate remediation objectives from which remediation end points may be defined. This process is set in terms of the overall goals and long-term vision for the condition and use of a site. It is these goals and long-term vision that will drive remedial efforts. The concepts of technical impracticability, clean-up to the extent practicable and clean-up to the extent necessary are described. These may be invoked in response to encountering technical and other factors limiting the success of remediation and preventing the desired end points being reached.

A summary of the nature and behaviour of LNAPL petroleum hydrocarbons in various subsurface settings is presented. This includes a general classification of subsurface environments and outlines the important differences in LNAPL behaviour in these settings. Descriptions of the major soil and aquifer systems of interest in Australia are also provided.

In terms of remediation technology selection, emphasis is placed on the process of identifying the risks and concerns associated with the presence of the LNAPL, defining remediation objectives to ameliorate these and establishing the remediation end points that will ensure these objectives are met. As part of this selection process, there is discussion of how specific risks may be addressed, particularly where they relate to individual constituents or classes of constituents of the LNAPL. Key to this is an understanding of how LNAPL mass reduction reduces specific risks or ameliorates particular concerns.

The report provides an extensive examination of the technologies available for LNAPL remediation. The most common in situ remediation technologies are examined along with approaches for the containment of LNAPL. These technologies are grouped as those based on: free-LNAPL recovery; volatilisation and biodegradation; engineered bioremediation; chemical flushing; in situ chemical oxidation; thermal methods and containment. Key factors in the selection of remediation technologies are identified as: the physical setting; remediation objectives and end points; and impacts of the remediation. These factors are imbedded in the steps presented for selecting a remediation technology for a particular site.

Process descriptions of 20 individual remediation technologies are provided, including how they relate to the key selection factors. To aid the preliminary screening of remediation strategies, tables of generalised effectiveness are presented. Effectiveness is rated in given settings, applicability to concerns, assessment of their impacts and other implementation factors. Such rankings and assessments are multi-dimensional in nature. Those given in the report are general in nature. However, how rankings and assessments will vary dependent on specific remediation objectives is emphasised. Also, the rankings and assessments are indicative and based on what is known of the underlying principles of the remediation technologies. The large number of permutations and lack of well-documented, published case studies on remediation effectiveness prevent greater use of field evidence in general rankings.

Stipulation and measurement of performance indicators are seen as fundamental for assessing candidate LNAPL remediation technologies. Performance indicators are also crucial in evaluating the implementation of particular remediation schemes. Ultimately, performance indicators are also used to decide when remediation should cease. A range of performance indicators applicable to the remediation technologies evaluated here are suggested for use. Also, underlying metrics (e.g. mass of LNAPL removed) are presented on which the performance indicators may be based.

Published Australian case studies were reviewed in an attempt to extract experience and guidance on LNAPL remediation performance in settings of particular significance in Australia. This review revealed a dearth of published case studies. Those readily available covered few of the possible remediation technologies and had a sparse coverage of the possible settings. Particular gaps were encountered in reporting of chemical flushing, in situ chemical oxidation and thermal methods. Surprisingly, some of the free product recovery techniques were also poorly reported. In relation to geological settings, gaps were evident in the experience reported for dual porosity materials and fractured rocks.

Full-scale implementation of an LNAPL remediation strategy is commonly preceded by some form of pilot-scale testing of candidate technologies. Here, the process of pilot testing is discussed in terms of how maximum benefit and appropriately representative results may be achieved. The report discusses appropriate performance indicators and metrics, variability, duration and end points of testing as well as the characterisation required for up-scaling and extrapolation.

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Technical Report 17: The Australian experience - A comparative analysis of the effects of contamination and its remediation on individuals and communities at two Australian sites

The potential environmental health risks to people living in proximity to contaminated sites garners legitimate interest by the surrounding communities in how the contamination and subsequent remediation and reuse of the land is managed by government and public agencies, and industry and commercial stakeholders.

The potential environmental health risks to people living in proximity to contaminated sites garners legitimate interest by the surrounding communities in how the contamination and subsequent remediation and reuse of the land is managed by government and public agencies, and industry and commercial stakeholders.

Significantly, studies exploring community perceptions and attitudes to land contamination and the related remediation within the Australian context are extremely limited. This project is designed to address this research gap in response to the need expressed by regulators, site managers and other practitioners in the industry to better understand how Australian communities perceive and experience contaminated land and its remediation.

Two case study sites were selected, both in New South Wales, Australia – the Botany Area (BA), consisting of the Botany Industrial Park and adjoining Southlands site, and the North Lake Macquarie Area (NLMA), consisting of the adjoining industrial sites of Pasminco Metal Sulphide Ltd and Incitec Pivot Cockle Creek. Both study sites have been exposed to a range of toxins from over a century of industrial activity, with the resulting contamination extending beyond the industrial property boundaries into the surrounding residential areas.

A mixed method research approach was adopted to generate primary empirical data on community perceptions of contaminated land and its remediation.  Methods included media content analysis, stakeholder analysis, community surveys, interviews and focus groups. The quantitative outcomes of the telephone surveys conducted are the key focus of this report, supplemented by the results of other qualitative research.

Similarities were found between the experiences and perceptions of the residents in the two case study sites, and those held by other research communities, both in Australia and internationally.

Five themes were identified for exploration in the project, and the following key findings emerged:

1. Levels of concern and interest. The survey showed a clear tendency for people to be concerned about the contamination in their local area, and an interest in keeping up to date with relevant information and with the progress of the remediation process. This was most prevalent in those over 35 years and lowest in those below 35 years of age. Interestingly, while respondents with children living in the household in the BA were more interested in keeping up to date with relevant information than those without children, this trend in interest was true for those without children living in the household in the NLMA. This may be a finding worthy of further research.

2. Risk communication, trust and confidence. While survey respondents from both sites had received their information from a variety of sources, the most frequently reported sources of information were the local media and the remediators, and to a lesser extent the local councils.

A major finding was that the levels of trust were the lowest for those sources from where the majority of information is being received; thus the information was treated as less trustworthy. The information sources that were rated most trustworthy, by respondents from both areas, were more ‘localised’ sources, i.e. community and environmental groups as well as local councils. This finding suggests that there is significant room for improvement in the practice of risk communication. In particular, making better use of sources deemed to be trustworthy, and also improving the trustworthiness of sources that are most readily accessed by residents.

The respondents also voiced concern about the value of information they were receiving, with the (perceived) poor quality and slim quantity appearing to amplify levels of distrust.

3.      Impacts on routines and lifescape. Focus group participants detailed the anxieties about health, distrust and a loss of control the impact of the contamination caused. While some participants indicated these losses were also felt as a result of the remediation, they also suggested they were often ameliorated as a result of the remediation.
 
The impact was felt most significantly within the home and affected the sense of security and safety they associated with their home. In the NLMA this largely involved increased cleaning routines to protect children from lead exposure, while in the BA changes were focused on the restriction on groundwater use.

The research highlighted:

  • how perceptions of the local area and the environment can become a source of concern, anxiety, stress and distrust, and
  • how trust in and reliance on personal experiences, or ‘tangible evidence’, was more highly valued by the communities than the expert, information-based evidence. 

4.      Stigma. A large proportion of residents from both sites believed that other people’s perception of their area was neither better nor worse off as a result of the contamination. A few respondents did however feel that other people’s perceptions were negatively affected by the contamination. There was a distinct difference in how residents felt the media portrayed the contamination between the two sites.
 
5.      Community capacity. An encouraging finding in this theme was the respondents’ strong sense that the community had been able to influence the remediation process. This suggests that proactive efforts from site managers to involve the community are likely to be well received, if presented as a genuine opportunity for involvement.
 
The majority of survey respondents felt that the contamination and remediation had no or little impact on community relationships. The remainder of respondents were split between those who felt it had brought people together and those who believed that it had been divisive. This highlights the importance of considering potential social polarisation. Moreover, focus needs to be given to those forces in the community that generate consensus – the shared acceptance generated through trusted community structures can play a key role, not only in the remediation process, but also with rebuilding levels of individual and community agency.
 
While approximately half of the survey respondents in both areas had discussed the contamination with their neighbours, far fewer had engaged in more active forms of community or individual action. By providing alternative and possibly more accessible opportunities for engagement may be another way for site managers and government agencies to improve affected residents’ level of satisfaction with the contamination management and remediation processes.

The themes explored in this research project, and the findings presented, provide a useful starting point for future research. The results warrant consideration by those charged with the regulation and management of contaminated sites in Australia, contributing to a deeper understanding of community perceptions, which in turn has the potential to inform the development of more effective community engagement practices across this industry.

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Technical Report 16: Safe on-site retention of contaminants. Part 2: A risk-based approach

Under the present regulatory regimes in the various states and territories of Australia, and internationally, it is common for contamination in excess of guideline levels to be allowed to remain on a site, and the project has arisen out of the need for a more transparent process for determining the circumstances under which this can occur. The project has involved a review of the regulatory requirements that are relevant, practice in the industry, and case examples.

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Technical Report 16: Safe on-site retention of contaminants. Part 1: Regulatory approaches and issues - a legal perspective

Site contamination issues present potentially significant impediments to land redevelopment in Australia. As the pressure mounts to contain urban sprawl in Australian cities, the desirability of higher density, inner city residential development is becoming widely accepted. Former railway yards, docklands and industrial sites have become prime targets for redevelopment. However, such sites present significant challenges with respect to remediation of the contamination that is commonly associated with them.

Site contamination issues present potentially significant impediments to land redevelopment in Australia. As the pressure mounts to contain urban sprawl in Australian cities, the desirability of higher density, inner city residential development is becoming widely accepted. Former railway yards, docklands and industrial sites have become prime targets for redevelopment. However, such sites present significant challenges with respect to remediation of the contamination that is commonly associated with them.

The established practice of excavating contaminants and disposing of them to landfill (‘dig and dump’) now faces serious challenge as policies to reduce the flow of wastes, particularly of a hazardous nature, to landfill sites are adopted by state and territory governments. One alternative that is economically attractive to developers is to leave significant amounts of contamination on the site (commonly referred to as ‘in-situ retention’) with varying levels of physical containment provided. This approach is presenting as an alternative to ‘dig and dump’ or other remediation methods where site-based risk assessment indicates that the option poses no significant risks to human health or the environment, provided that the relevant containment measures are not breached.

Within the community the in-situ retention approach is likely to be met with the suspicion that it involves ‘covering up’ the problem. Regulators, in turn, are wary of endorsing an option that may be widely opposed by an affected community. Similarly, environmental auditors may be adopting a cautionary approach to the selection of remediation options, preferring to endorse clean-up to background values rather than retention in situ. This may, in turn, be discouraging the market for site remediation projects from operating in some instances. The remediation industry, developers and the community could all benefit from further clarity as to when it is appropriate to adopt the approach of in-situ retention for the purpose of remediation of a contaminated site.

This report examines a range of legal and policy issues that arise where in-situ retention is proposed as a remediation strategy. It surveys the current state of relevant law and policy across a number of jurisdictions within Australia, and explores how the same issues have been addressed in various jurisdictions in North America and Europe. Its conclusions are summarised in the section immediately following this executive summary.

There are four specific issues that have been identified and addressed in this report:

  • the adequacy of the current regulatory framework for dealing with contaminated sites in terms of providing appropriate guidance as to when in-situ retention is an acceptable remediation strategy
  • the need for appropriate legal mechanisms (referred to commonly as ‘institutional controls’) alongside specific engineering measures to ensure that there is effective long-term management (or ‘stewardship’) of sites where contaminants are retained in situ
  • the extent to which those parties undertaking remediation via the in-situ retention method (in many cases, voluntarily in the course of redeveloping land) may be exposed to a future, ‘residual’ liability for such sites – for example, if unanticipated impacts occur, new treatment methodologies emerge or later owners do not comply with the relevant institutional controls
  • the potential overlap between site contamination and waste management legislation where in-situ retention is proposed as a remediation strategy.

Our broad conclusion with respect to each of the above matters is that there is currently a lack of both sufficient specific policy guidance at the national level and appropriate guidance within relevant state/territory legislation and policy instruments. We found, in particular, that relevant state legislation has an ‘open-textured’ character that fails to provide specific guidance on remediation options generally, and with respect to in-situ retention specifically. This has the potential to result in inconsistencies in approach to remediation between similar cases, and reduces the degree of accountability of a range of decision-makers when determining the acceptability of proposed strategies. The resultant uncertainty is compounded by the degree of responsibility that has been vested in environmental auditors in most jurisdictions to determine the appropriate remediation strategy in any particular situation.

Conceivably, these shortcomings could be addressed collectively by policy-makers through the Environmental Protection and Heritage Council (EPHC) in the first instance. This could pave the way for each jurisdiction to implement the outcomes of the EPHC process through their respective legislative and policy mechanisms.

In addition, we identify a significant lack of specific legal measures, in the form of institutional controls, to address the challenge of ensuring sound, long-term management of sites at which contaminants have been retained in situ. In particular, no consistent approach to this important aspect of in situ retention has yet been developed in Australia, in distinct contract to the United States experience with the Uniform Environmental Covenants Act. We also identify a similar lack of specific measures with respect to the question of residual liability for sites where contaminants have been retained in situ. In addition, a potential problem, based on recent experience in the European Union, with the possible overlap of waste management and site contamination laws where in-situ retention is envisaged.

Finally, we note a deeper, unresolved issue with respect to compatibility of the in-situ retention approach to site remediation with the concept of sustainability that is now commonly enshrined (in the form of principles of ‘ecologically sustainable development’ (ESD)) in the objects clauses of much environmental legislation in Australia. It may be argued that in-situ retention is simply deferring the resolution of site contamination problems to future generations, which is contrary to the principles of ESD—at least unless both the technical and legal controls applicable to sites treated in this way can be guaranteed to be effective. This issue, at the very least, heightens the need for development of the specific measures recommended in this report if the practice of in-situ retention is to gain wider acceptance as a remediation strategy in Australia.

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Technical Report 15: A technical guide for demonstrating monitored natural attenuation of petroleum hydrocarbons in groundwater

Natural attenuation (NA) refers to the reduction in quantity and concentration of contaminants over time as a result of naturally occurring physical, chemical and biological processes within soil and groundwater. Under certain conditions, NA can be applied for remediation and/or management of contaminants in soil and groundwater. However, in order to manage the risks associated with this strategy, the NA processes need to be monitored. This phenomenon is called monitored natural attenuation or MNA.

Natural attenuation (NA) refers to the reduction in quantity and concentration of contaminants over time as a result of naturally occurring physical, chemical and biological processes within soil and groundwater. Under certain conditions, NA can be applied for remediation and/or management of contaminants in soil and groundwater. However, in order to manage the risks associated with this strategy, the NA processes need to be monitored. This phenomenon is called monitored natural attenuation or MNA.

This document provides technical guidance on how MNA can be applied as a remediation and/or management strategy for addressing potential environmental and human health risks associated with petroleum hydrocarbon contamination in groundwater. It is important to note that this document only focuses on technical considerations in demonstrating MNA, and does not provide specific guidance on the application of the legislative frameworks on groundwater remediation and management in different states of Australia.

As a guiding principle, MNA strategy must first consider the local regulatory requirements for protection of environment and human health, and restoration of beneficial uses of groundwater. Australian regulatory authorities generally recognise the very real difficulties involved in remediation of groundwater contamination.  Some states provide for ‘clean up to the extent practicable’ (CUTEP)’ or ‘remediation to the extent necessary’ (RTEN). MNA can be an appropriate approach in these circumstances. There is no generally accepted time frame for MNA to achieve results, and this is also a matter for regulatory agencies taking into account the particular circumstances. Consideration of the principle of intergenerational equity suggests that contaminated groundwater should be remediated within a single generation.

In order to implement MNA strategy, it is important that there is a sound understanding of the contaminant plume, and a robust conceptual site model is developed. In addition, sustainability, financial, legal and liability considerations should also be taken into account.

The guidance suggests a staged approach to implementation of MNA to optimise efficiency and economics of the process:

Stage 1: Preliminary assessment, feasibility and acceptability, which consider issues such as sustainability, timeframe, legal and liability issues for applying an MNA strategy

Stage 2: Initial evaluation of natural attenuation, which considers the source characterisation and assessment of technical indicators of NA

Stage 3: Detailed characterisation through demonstration of primary, secondary and tertiary lines of evidence for NA processes

Stage 4: Verifying performance of NA, which includes a comprehensive monitoring plan, and

Stage 5: Achieving closure, which includes documentary requirements to demonstrate that goals have been achieved.

 

To aid this staged approach, information is provided on understanding:

  • the hydrogeological processes involved
  • the lines of evidence needed to assess and demonstrate NA
  • the limitations and uncertainties involved, data requirements, and
  • achieving closure goals.

MNA should not be used where it would result in significant contaminant migration (i.e. expanding plumes) or unacceptable impacts to receptors. Sites, where the contaminant plumes are stable or shrinking in size, are considered the most appropriate candidates for MNA approaches.

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Technical Report 14: Contaminant bioavailability and bioaccessibility. Part 2: Guidance for industry

When determining the impact of an ingested chemical on human health risk assessment, the chemical’s toxicity is influenced by the degree to which it is absorbed from the gastrointestinal tract into the body (i.e. its bioavailability). As oral references doses (RfDs) and cancer slope factors (CSFs) are generally expressed in terms of ingested dose, rather than absorbed dose, the variability in absorption between different exposure media, chemical forms etc. may significantly influence risk calculations.

When determining the impact of an ingested chemical on human health risk assessment, the chemical’s toxicity is influenced by the degree to which it is absorbed from the gastrointestinal tract into the body (i.e. its bioavailability).  As oral references doses (RfDs) and cancer slope factors (CSFs) are generally expressed in terms of ingested dose, rather than absorbed dose, the variability in absorption between different exposure media, chemical forms etc. may significantly influence risk calculations. In Australia, NEPM health investigation levels (HILs) are highly conservative and derived using a bioavailability default value of 100%.  However, the assumption that 100% of the soil-borne contaminant is bioavailable may overestimate exposure thereby influencing risk calculations.  As a result, assessment of contaminant bioavailability may help refine exposure modelling for Tier 2 human health risk assessment.

This guidance document is limited to evaluating the bioavailability of contaminants via the incidental soil ingestion pathway and is based on a comprehensive review (Ng et al. 2010) undertaken as part of recommendation 24 of the National Environmental Protection Measure (NEPM) five-year statutory review.  The majority of bioavailability research has focused on inorganic contaminants such as arsenic and lead, which forms the basis of this guidance document.

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Technical Report 14: Contaminant bioavailability and bioaccessibility. Part 1: A scientific and technical review

Site assessment on land potentially affected by contamination is often undertaken at the termination or transfer of property leases, on property sale, as part of redevelopment to new and often more sensitive land uses, or for sites that pose unacceptable human health and environmental risk and are the subject of statutory assessment and remediation notices. Inadequate assessment that may over or understate the risk of site contamination can result in significant cost burdens for development with resulting negative impacts on economic growth.

The NEPM has undergone a statutory five-year review resulting in a Review Report consented to by the National Environment Protection Council (NEPC) in November 2006.  The report makes 27 recommendations including one relating to the provision of guidance on bioavailability and associated leachability testing methods and their application.  A Variation Team has been established by the NEPC to implement the report recommendations.  Site assessment on land potentially affected by contamination is often undertaken at the termination or transfer of property leases, on property sale, as part of redevelopment to new and often more sensitive land uses, or for sites that pose unacceptable human health and environmental risk and are the subject of statutory assessment and remediation notices.  Inadequate assessment that may over or understate the risk of site contamination can result in significant cost burdens for development with resulting negative impacts on economic growth.

An integral part of site assessment involves reference to interim urban ecological investigation levels (EILs) and health investigation levels (HILs) as screening criteria for soil contaminants.  Provided competent site investigation processes are followed, chemical analyses of soil that fall below the EILs and HILs usually mean that no further site investigation or management are required depending on the land uses involved.  When these levels are exceeded, site-specific qualitative or quantitative health and environmental risk assessment is required.  The results of these risk-based approaches are related to proposed land uses and conditions that may be needed for the ongoing management of site contamination.

The NEPM HIL derivation methodology includes the conservative assumption that the contaminant of concern is 100% bioavailable.  In most cases the actual bioavailability of the soil contaminant to humans and other organisms is significantly less.  An accurate determination of bioavailability enables more realistic site-specific remediation criteria to be developed when a detailed health risk assessment is undertaken.  Apart from human health concerns, bioavailability testing methods may also affect determination of acceptable soil criteria for ecological protection in relation to effects of contaminants on domestic and native animals, soil organisms and exotic and native flora.  This report specifically addresses Recommendation 24 as scoped by the variation team.

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Technical Report 13: Field assessment of vapours

Australia has no current guidance on the field assessment of volatile compounds for sites where vapours have the potential to migrate into buildings and pose risks to human health. There are recommendations to provide such national guidance. This report updates knowledge available internationally related to guidance and methods of vapour assessment. It is intended to be used with other documentation to inform the variation of the Australian National Environment Protection (Assessment of Site Contamination) Measure (NEPM) currently underway.

Australia has no current guidance on the field assessment of volatile compounds for sites where vapours have the potential to migrate into buildings and pose risks to human health. There are recommendations to provide such national guidance. This report updates knowledge available internationally related to guidance and methods of vapour assessment. It is intended to be used with other documentation to inform the variation of the Australian National Environment Protection (Assessment of Site Contamination) Measure (NEPM) currently underway.

In this report:

  • the processes underlying vapour behaviour are described
  • available guidance is reviewed
  • a framework for vapour assessment and screening is suggested
  • design issues for field assessment of vapours are described
  • investigation and sampling techniques are compared, and
  • observations from the work are summarised.

It is found that a well-described conceptual site model (CSM) of vapour risk embodies understanding of site conditions, potential vapour behaviour, and priorities for investigation. It serves as the basis for vapour risk assessment along with data quality objectives (DQOs).

Extensive vapour intrusion and assessment guidance documentation has been developed within the United States of America and by industry, but limited guidance is available for other countries. A staged approach (Tier 1, 2, 3 or 4) for vapour assessment is generally adopted across nearly all guidance, however, the breadth of investigation required in each stage is not consistent across the available guidance. The stages of investigation for vapour assessment do not always align with accepted stages of a more general site investigation (Phase I or Phase II Environmental Site Assessments – ESAs, or Preliminary/Detailed Site Investigations ­– PSIs/DSIs).

There is substantial information that would support an exclusion distance approach applicable at a Tier 1 screening level, whereby if a property or building is beyond a set distance to the edge of a vapour source, then it could be excluded from further investigation. Consideration of the use of soil gas vapour concentrations (representative of the direct pathway of exposure), rather than soil concentrations alone, for comparison to health-based investigation level (HIL) screening values seems warranted. In Australia, this may require the development of soil gas HILs for volatile compounds. Where soil vapour assessment techniques are not used at Tier 1, then soil and/or groundwater investigations will be required to assist in the definition of the exclusion distance or to provide data for comparison to HIL screening values.

A variety of vapour assessment techniques are available. Advantages and disadvantages of many are tabulated. Choices of vapour investigation approaches should target improvement and modification of the CSM. Guidance documents recommend a number of approaches. Common elements are, where required and practical, (a) subsurface soil gas samples should be taken no shallower than 1 m, unless adequately justified, (b) to determine maximum vapour concentrations in the subsurface, samples should be recovered as close as possible to the source (it is acknowledged that this may be particularly difficult for groundwater sources and may not be warranted for very deep sources), and (c) depth profiles can be useful.  Seasonal and short term atmospheric changes (barometric, etc.) can influence vapour concentrations but this effect decreases rapidly with depth depending on the period of the transient disturbance and the re-equilibration time of the vapour concentrations through the soil profile. Vapour behaviour may need to be assessed over time where shallow sampling is undertaken and where transient behaviour might be expected to occur.

Most experience and investigations have been carried out for petroleum hydrocarbons and chlorinated solvent vapours. Whilst the techniques and approaches may be valid for use for other volatile compounds, for some compounds (e.g. mercury, butadiene) there is limited experience, and hence careful adoption of field approaches would be required.

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Technical Report 12: Biodegradation of petroleum hydrocarbon vapours

In this report we review the role of biodegradation in reducing petroleum hydrocarbon vapour intrusion into slab-on-ground buildings for application at a Tier 1 or human health screening level. This work comprises part of the efforts through CSIRO and the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) to provide technical input to the current review of the Australian National Environment Protection (Assessment of Site Contamination) Measure (NEPM).

In this report we review the role of biodegradation in reducing petroleum hydrocarbon vapour intrusion into slab-on-ground buildings for application at a Tier 1 or human health screening level. This work comprises part of the efforts through CSIRO and the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) to provide technical input to the current review of the Australian National Environment Protection (Assessment of Site Contamination) Measure (NEPM).

Vapours emanate from subsurface spills and leaks of petroleum fuels such as gasoline, diesel and other petroleum products. Historic or recent events may lead to contamination, and investigation of vapour risks may be triggered by previous site investigations, knowledge of site history or use, or where land redevelopment is occurring. Vapours naturally attenuate or decrease in concentration as they move from the subsurface through the soil towards the ground surface and potentially into buildings. Here we consider the additional attenuation potential due to aerobic biodegradation of petroleum hydrocarbon vapours, and the consequent additional reduction in human health exposure that may be applicable at a Tier I or screening level. The report relates to the evaluation of long-term chronic low-level indoor air concentrations of petroleum hydrocarbon chemical constituents, rather than short-term concerns such as high-level explosive hazards or acute toxic concentrations.

Included in this report are: (i) published information on the biodegradation of petroleum hydrocarbon vapours; (ii) additional exposure reduction factors proposed by researchers and suggested by jurisdictions attributable to biodegradation of petroleum hydrocarbon vapours; (iii) data on petroleum hydrocarbon vapours and oxygen concentrations from four states of Australia along with an assessment of generalised trends; (iv) recommendations as to reduction factors that might be applied when oxygen is present in the subsurface and aerobic biodegradation of petroleum vapours is occurring; and (v) guidance on the application of such reduction factors.

The studies and modelling suggest that where oxygen was present petroleum vapours degraded rapidly. Where oxygen was absent little biodegradation was observed.  Additional attenuation due to biodegradation of petroleum hydrocarbon vapours have been reported to vary from 1 (i.e., no change) to many orders of magnitude, depending on the depth to the source of vapours, the concentration resident in the source zone, and the potential for oxygen ingress. Australian and overseas data from studies in and beneath buildings show that significant biodegradation occurs, especially for modest sized buildings.

Four recommendations are made concerning:

  1. the need for measurement and confirmation of the presence of oxygen in the subsurface
  2. an exclusion/inclusion criterion related to depths to vapour sources
  3. an exclusion/inclusion criterion related to the scale of the building foundations to which the recommendations apply, and
  4. the magnitude of the additional exposure reduction that is applicable at a Tier 1 or screening level due to biodegradation of petroleum hydrocarbon vapours.

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Technical Report 11: Characterisation of sites impacted by petroleum hydrocarbons - National guideline document

Sites impacted by petroleum hydrocarbons represent a significant proportion of Australia’s contaminated land, and proper characterisation of these sites is therefore a major concern. Poorly planned and executed site characterisation is likely to result in additional expense, both during the investigation and subsequent remediation, and inadequate or misleading data may also result in an increased risk to human health and the environment.

Sites impacted by petroleum hydrocarbons represent a significant proportion of Australia’s contaminated land, and proper characterisation of these sites is therefore a major concern. Poorly planned and executed site characterisation is likely to result in additional expense, both during the investigation and subsequent remediation, and inadequate or misleading data may also result in an increased risk to human health and the environment. A number of guidance documents related to contaminated site characterisation currently exist in Australia; however, these are typically regional, outdated or do not provide information specific to characterising petroleum hydrocarbon impacts.

CRC CARE, in consultation with industry, consultants and regulators, recognised the need to prepare national guidelines for the characterisation of petroleum hydrocarbon impacted sites, to unify current guidance and provide support for innovative technologies and approaches. These guidelines have therefore been prepared under CRC CARE’s National Contaminated Sites Demonstration Program. Preparation of the guidelines forms part of a larger Site Characterisation Project scope, which has also included the formation of a Petroleum Projects Project Advisory Group (PAG) to provide direction and feedback from industry, consultants, researchers and state regulators. A review of relevant existing Australian and international guidance, protocols and techniques has also been previously completed (Davis et al. 2006) and taken into consideration during the development of these guidelines.

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Technical Report 10: Health screening levels for petroleum hydrocarbons in soil and groundwater

CRC CARE has undertaken the development of health-based screening levels (HSLs) for petroleum hydrocarbons to address an identified need for consistent human health risk assessment of petroleum hydrocarbon contamination in Australian conditions. The HSLs represent the best collective view of the available science and application of Australian approaches on selection of health criteria and exposure parameters. The document underwent several international peer reviews by experts in the United States, Canada and Australia. Given the innovative nature of the work, CRC CARE will monitor national and international developments, and publish updates as and when necessary.

More information on health screening levels, including extension models downloads, is available here.

CRC CARE has undertaken the development of health-based screening levels (HSLs) for petroleum hydrocarbons to address an identified need for consistent human health risk assessment of petroleum hydrocarbon contamination in Australian conditions. The HSLs represent the best collective view of the available science and application of Australian approaches on selection of health criteria and exposure parameters. The document underwent several international peer reviews by experts in the United States, Canada and Australia. Given the innovative nature of the work, CRC CARE will monitor national and international developments, and publish updates as and when necessary.

The HSLs and the underlying methodology may be used for health risk assessment purposes in the context of the wider site assessment framework for petroleum hydrocarbon contamination provided in the Assessment of Site Contamination NEPM as varied. It should be noted that the HSLs were derived through the consideration of health effects only, with particular emphasis on the vapour exposure pathway. Other considerations such as ecological risk, aesthetics, the presence of free phase product and explosive/fire risk will need to be assessed separately, as they are not addressed by the HSLs.

It is strongly recommended that the HSL technical development document and the associated documents (Part 2: Application document, Part 3: Sensitivity assessment and Part 4: Extension model) are referred to for the key assumptions for the derivation of the HSLs, and for their application and limitations on their use.

The assessment of contamination using health-based screening criteria and investigation thresholds is a complex matter. While every effort has been made to identify and assess the significant risks to human health associated with petroleum hydrocarbon contamination, it is strongly recommended that assessments are carried out by appropriately qualified and experienced persons (who understand the context, requirements and limitations of such use), in consultation with the relevant jurisdiction.

Many of the assumptions that underlie the HSL values involve policy decisions. It is possible that future reviews may lead to changes in the assumptions and the values of the HSLs. It is, therefore, important to check the CRC CARE website for relevant updates at the time of the assessment.

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Technical Report 09: Petroleum vapour model comparison

The review of the Australian National Environment Protection (Assessment of Site Contamination) Measure (NEPM), and workshops in Australia over a number of years involving regulators, industry representatives, consultants and researchers, have motivated the need to review and recommend a model of vapour behaviour for use in the development of health-based screening levels (HSLs) in Australia. In particular, suggestions from a recent workshop held on the Gold Coast Queensland, Australia in February 2008 led to the development of this summary report.

The review of the Australian National Environment Protection (Assessment of Site Contamination) Measure (NEPM), and workshops in Australia over a number of years involving regulators, industry representatives, consultants and researchers, have motivated the need to review and recommend a model of vapour behaviour for use in the development of health-based screening levels (HSLs) in Australia.  In particular, suggestions from a recent workshop held on the Gold Coast Queensland, Australia in February 2008 led to the development of this summary report.

Here, the processes underlying vapour behaviour are described and two models are compared for their utility in modelling petroleum vapours in soil profiles and as they move from the subsurface into built structures. In addition, the need for inclusion of biodegradation and finite lifetime sources in modelling approaches during the development of HSLs is considered.

Four primary recommendations are made concerning:

  1. a model appropriate for immediate development of petroleum vapour HSLs in Australia
  2. the need for additional National Workshops to develop the built environment scenarios that should be modelled for Australia and to agree the parameter values that will be used in the models
  3. the need to include biodegradation in development of less conservative HSLs, and
  4. the need to incorporate finite or infinite sources in vapour models.

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Technical Report 08: Review of the current international approaches to total petroleum hydrocarbon assessment

This was designed to ascertain the basis to decisions on differences in the use of the Total Petroleum Hydrocarbon Working Group (TPHCWG) hydrocarbon fractions that are used internationally but are subject to adjustment in some cases. This was an outcome associated with discussions arising from the Technical Working Group and Petroleum Project Advisory Group meetings held in Melbourne on 20 November 2007 and 29 November 2007 where the outcomes of the working document on total petroleum hydrocarbons were presented.

Coffey Environments Pty Ltd was commissioned by the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) to prepare a detailed review of the background to the respective international approaches on total petroleum hydrocarbons.  This was designed to ascertain the basis to decisions on differences in the use of the Total Petroleum Hydrocarbon Working Group (TPHCWG) hydrocarbon fractions that are used internationally but are subject to adjustment in some cases.  This was an outcome associated with discussions arising from the Technical Working Group and Petroleum Project Advisory Group meetings held in Melbourne on 20 November 2007 and 29 November 2007 where the outcomes of the working document on total petroleum hydrocarbons were presented.

The objective is to provide a detailed review of the background to respective international approaches on total petroleum hydrocarbons in order to ascertain the basis to decisions on differences in the use of the TPHCWG fractions and associated toxicological, fate and transport data and the specified scope of works including an examination of:

  • the US Agency for Toxic Substances and Disease Registry (ATSDR)’s position on total petroleum hydrocarbons (TPH), based on their current documentation
  • the Netherlands, Institute of Public Health and the Environment (RIVM)’s use of an extended range of TPH fractions based on recent publications
  • the UK Department of Environment’s use of an extended range of TPH fractions as presented in regulatory publications
  • the Canadian Council of Ministers of the Environment (CCME)’s use of a reduced series of TPH fractions as detailed in regulatory publications, and
  • the New Zealand (NZ) approach in the use of AIP fractional approaches that are a reduced group of fractional ranges as presented by the NZ Ministry for the Environment (MfE).

The review strategy encompassed a literature review of regulatory publications in this area and related documentation and email correspondence to a range of international regulatory scientists, consultants, researchers and academics through personal and public networks.

A consistency in terms of the background information used in the development of TPH fractional approaches was identified with regional adjustments including:

  • the use of risk-based techniques of assessment common to all areas
  • staged approaches in the site assessment of petroleum-hydrocarbon impacted land
  • the use of specific indicator substances such as carcinogens (benzene, benzo[a]pyrene) and commonly encountered contaminant non-carcinogens such as ethylbenzene, toluene, xylenes and naphthalene, followed by TPH fractions, and
  • the assessment of TPH fractions undertaken either concurrently with, or sequentially to, the indicator substances.

Table 7 summarises the information relevant to each national position across these issues.

Selection of fractions and data for toxicological evaluation and fate and transport characteristics has consistently been drawn from the work of the TPHCWG.  The adaptation of that work, however, has differed from minor adjustment to reduction of the numbers of TPH fractions using various methods including, in some cases, adjustment of toxicological endpoints.  In addition, although some commonality exists for TPH fractional analytical procedures each agency has examined or documented specific procedures for evaluation or implementation.

ATSDR has directly captured the TPHCWG fractions with an extension of the aromatic equivalent carbon (EC) range of >EC5-EC8 of the TPHCWG to aromatic EC>5-EC9 to capture all the BTEX substances in this range.  This has also been adopted by RIVM.  The ATSDR then use the 13 fractions for fate and transport evaluation and the exposure assessment with consolidation of ranges into the seven toxicity fractions for evaluation.  RIVM is also consistent with this approach in deriving their updated maximum permissible risk values.

The UK Environment Agency has undertaken extensive consultation on TPH approaches and has extended the TPH fraction range to also include aromatic   >EC35-44 for both aliphatic and aromatic ranges and a combined >EC44-70 range.  The implementation of their recommendations is currently under consideration.

The CCME and New Zealand MfE have adopted a reduction in TPH fractions in their documentation embodying weighted averaging approaches and assumptions on the distribution of aromatic and aliphatic components.  The CCME presents its approach using a combination of TPHCWG data and product composition in conjunction with regional evaluation of fresh product in terms of aromatic and aliphatic components to determine this distribution.  The New Zealand basis uses an emphasis on specific indicator substances and a special case for PAHs in diesel in reducing dependence on the assessment of TPH aromatics.  The weighting procedure for the aliphatic ranges, however, is not detailed.  The NZ MfE has also undertaken a consultation phase and is currently reviewing its position on TPH assessment based on consultation outcomes.

The international perspective as presented for these agencies is one of dynamic flux with a number of agencies currently reviewing their position on the approach to TPH.  The CCME and RIVM positions appear the most consolidated, incorporating both human health and eco-toxicological evaluations.  The ATSDR position has not changed and, although a huge amount of documentation has been generated in the United States, jurisdictional uptake has varied considerably with an apparent diversity of approaches.  In all cases regional considerations have factored significantly in the process of determining suitable frameworks.

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Technical Report 07: Development of policies for the handling, disposal and/or beneficial reuse of used foundry sands - a literature review

A large amount of research conducted recently and practical experience gathered worldwide over the last 30 years has indicated that with very few exceptions, beneficial reuse of used foundry sand (UFS) is not detrimental to human health or the environment.

A large amount of research conducted recently and practical experience gathered worldwide over the last 30 years has indicated that with very few exceptions, beneficial reuse of used foundry sand (UFS) is not detrimental to human health or the environment.

 

Characteristics

  • UFS is not uniform and the type of contaminant issues that may be experienced varies both spatially and temporally. Spatial variation is due to the differences in procedures and foundry processes which vary from one company to another and from one application to another. The main differences occur between foundries that use green sands to produce moulds, as opposed to foundries which use resin sands with a higher content of organic contaminants due to the organic resin binders used to prepare moulds. Temporal variations in UFS consistency can occur even at the same location due to changes in foundry production.
  • UFS is currently poorly characterised with regard to the type and extent of contaminants, especially organic contaminants including potentially unhealthy contaminants such as polyaromatic hydrocarbons (PAHs) produced during the foundry process at elevated temperatures due to pyrolytic reactions. There is a need to better understand how these reactions occur so they can be controlled and minimised.
  • Most organic residues are present in UFS at low concentrations, usually below detection limits. When detected the organic residues are either PAHs (phenanthrene, naphthalene, fluorene, anthracene and pyrene) or phenolic compounds (phenol, 2-methyphenol, 3- and 4-methylphenol and 2,4-dimethyl phenol). 

 

Beneficial reuses

  • While a number of beneficial uses have been proposed, few are economically viable unless the foundry and the site of reuse are close and thus limit the costs associated with transporting UFS for treatment or reuse.
  • Beneficial reuses that are well advanced include many construction applications, whereas agricultural application of UFS is limited, not due to any real environmental concern but rather the perception that UFS will be detrimental to human health. Indeed, substantial research conducted worldwide has indicated that metal contaminants in UFS, especially those derived from green sands, are not of environmental concern and are often present at levels comparable to native soils.
  • Several studies have indicated that UFS from brass foundries are generally not suitable for beneficial reuse due to high levels of metal contaminants.
  • For land application of UFS, greater research needs to be conducted to unequivocally demonstrate that UFS as part of a manufactured soil is completely safe.

 

Legislative aspects

  • A number of legislative frameworks have been adopted worldwide. The more successful of these use some form of classification of UFS based on specified criteria for both metal and organic concentrations, usually TCLP (toxicity characteristic leaching procedure) extraction, and then define specifically what reuse is applicable to that classification.
  • While the levels of metal contamination in UFS are normally well below any legislated levels of concern and are often comparable to the original clean sand, organic contaminants are poorly characterised in UFS and are consequently poorly legislated for. In part this results from the plethora of different potential organic binder technologies currently in use.
  • Lack of clarification by the state EPAs as to what criteria would be suitable for classification of UFS is one of the major barriers to successfully reusing UFS. This is coupled with disagreement between states on clear legislative guideline levels for different contaminants.
  • There is a need to streamline the approvals process to encourage beneficial reuse.
  • Research is required to establish not only the types of UFS constituents, but also the magnitude of investigation levels for these constituents that would be required to ensure protection of the environment and human health.
  • Legislative guidelines should include information on sampling plans and the frequency of sampling required.

 

Further research

In the short term the most pressing need for industries and regulators intent on the adoption of beneficial reuse of UFS is to focus on dialogue that fosters beneficial reuse. The development of regulatory guidelines which address the needs of industries in clear and unequivocal terms needs to be a priority. Generic guidelines are not required, rather, a clear statement of what is required on the quality of UFS fit for a specific purpose. There is a need for guidelines to be developed specifically for the reuse of UFS.

These guidelines should initially focus on land application, which would be the most difficult to define and implement due to the greatest potential risk associated with this reuse. However, reuse should not be limited to this avenue alone as many other applications such as road base and construction are relatively low risk alternatives that can quickly be used to demonstrate beneficial reuse.

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Technical Report 05: The development of a modular, constructed wetland system for salt, organic and nutrients removal from dairy wastewaters

This is the final report of a desk-top study designed to provide ‘proof-of-concept’ for the use of the giant reed (Arundo donax) in constructed wetland systems designed to remove contaminants from dairy processing factory wastewater streams. Activities were therefore restricted to information collection, collation and evaluation. No field or laboratory activities were planned or have been conducted. The following conclusions and recommendations can be made with respect to the objectives of the project.

This is the final report of a desk-top study designed to provide ‘proof-of-concept’ for the use of the giant reed (Arundo donax) in constructed wetland systems designed to remove contaminants from dairy processing factory wastewater streams. Activities were therefore restricted to information collection, collation and evaluation. No field or laboratory activities were planned or have been conducted. The following conclusions and recommendations can be made with respect to the objectives of the project.

The giant reed is a perennial, herbaceous plant found in grasslands and wetlands over a wide range of climatic and habitat conditions. The giant reed is found in most parts of Australia, including in Victoria, but is not listed as a noxious or invasive weed Australia-wide, although it is locally declared in New South Wales (and thus its use is also prohibited in Western Australia). The giant reed is not a declared weed in Victoria, and is apparently readily available from a number of garden suppliers. However, A. donax has some traits, such as fast growth rate, diffusion via flood-mediated rhizome dispersion, rapid re-growth after fire, and invasion of riparian zones that make it a potential weed. Before A. donax is used in constructed wetlands in Victoria, South Australia, Queensland, the ACT, Northern Territory or Tasmania, consideration should be given to a detailed survey of its distribution within the relevant state. Such a survey should include an ecological assessment of local and/or regional adaphic and biotic factors that may constrain or promote its ability to become a weed.

Arundo donax has some characteristics that make it suitable for use in constructed wetlands for wastewater treatment. These include its fast growth rate, high water consumption, apparent salt tolerance (still to be confirmed), ease of propagation from rhizomes, limited reproduction from seed (reduced risk of off-site dispersal), limited number of pests, and the many potential uses for above-ground biomass. There is limited information on the use of A. donax in constructed wetlands, although the giant reed has been planted in several research and treatment wetlands (e.g. in Arizona and Crete). Very little treatment performance data is available for these wetlands, although the tendency for impenetrable stands of A. donax to rapidly dominate reed-bed systems has been noted.

Constructed wetlands are currently not able to remove sodium originating in factories and associated anaerobic water treatment plants. However, finding plants able to tolerate high salt loads could facilitate the use of constructed wetlands to ameliorate the organic and nutrient loads being discharged by factories. Insufficient detailed information on A. donax exists to adequately assess the advantages and limitations of A. donax compared with other common wetland plants (e.g. Phragmites australis). Consideration should be given to the establishment of pilot scale wetlands using A. donax to:

  • examine the effectiveness of the giant reed (A. donax) in stripping nutrients and organic material from effluent by evaluating chemical transport, assimilation and release in pilot scale constructed wetlands, and in comparison with the common reed (Phragmites australis)
  • assess the salt tolerance of A. donax
  • examine options for the sustainable re-use of the biomass produced by A. donax
  • investigate management techniques to minimise risk of escape of A. donax from constructed wetlands.

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Technical Report 04: The development of HSLs for petroleum hydrocarbons - an issues paper

In Australia, the normal approach for triggering further investigation during contaminated land investigations is to determine whether the concentration of contaminants of concern in soil and/or groundwater exceed published health screening levels (HSLs) or ecological investigation levels (EILs). These levels can also form the basis for clean-up criteria. In the case of petroleum hydrocarbons, a number of HSLs exist; however, these are limited and do not extend to a variety of soil types and aquifer situations, or to the assessment of volatile hydrocarbons.

????In Australia, the normal approach for triggering further investigation during contaminated land investigations is to determine whether the concentration of contaminants of concern in soil and/or groundwater exceed published health screening levels (HSLs) or ecological investigation levels (EILs).  These levels can also form the basis for clean-up criteria.  In the case of petroleum hydrocarbons, a number of HSLs exist; however, these are limited and do not extend to a variety of soil types and aquifer situations, or to the assessment of volatile hydrocarbons.  There is guidance on how the assessment of risk associated with such contaminants should be carried out, and it is common practice to undertake a risk assessment to determine whether the concentrations might pose a human health or ecological risk.  As such, there is a basis for developing a set of HSLs and clean-up guidelines for petroleum hydrocarbons, but the detail of this has not yet been agreed and carried out.

The Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) research program includes Subprogram 1.4: Risk Characterisation and Communication, which includes the objective of preparing HSLs for hydrocarbons in soil and groundwater.  This project forms part of this program, and has the objective of developing an accepted set of HSLs and clean-up guidelines for petroleum hydrocarbons in soil and groundwater, in the context of land uses and the beneficial use of groundwater typical of Australia.

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Technical Report 03: Natural attenuation - a scoping review

‘Natural attenuation’ refers to naturally occurring physical, chemical and biological processes, or any combination of those processes, that reduce the concentration or mass of polluting substances in groundwater. It has been recognised that natural attenuation processes can form the basis of a viable remediation strategy for contaminated sites. Monitored natural attenuation has the potential to reduce contaminant clean-up costs while avoiding exposures to humans and sensitive environmental receptors. Whilst the benefit of using monitored natural attenuation on a site can be significant compared with active remediation, there are also risks associated with this strategy that need to be managed.

‘Natural attenuation’ refers to naturally occurring physical, chemical and biological processes, or any combination of those processes, that reduce the concentration or mass of polluting substances in groundwater. It has been recognised that natural attenuation processes can form the basis of a viable remediation strategy for contaminated sites. Monitored natural attenuation has the potential to reduce contaminant clean-up costs while avoiding exposures to humans and sensitive environmental receptors. Whilst the benefit of using monitored natural attenuation on a site can be significant compared with active remediation, there are also risks associated with this strategy that need to be managed.

CRC CARE commissioned this review of natural attenuation processes as part of its priority scopes of work related to the environmental fate of petroleum hydrocarbons. The goal of the scoping report was to review international, national and industry information about the natural attenuation of petroleum hydrocarbons with a focus on Australian studies. This project seeks to identify scientific knowledge gaps which are relevant to the application of monitored natural attenuation in Australia.

The following are the major observations arising from this review:

  1. A risk-based approach using lines of evidence is widely used as a framework for monitored natural attenuation (MNA) guidance.
  2. Six years ago, MNA was recognised as a well-established remediation approach for only a few types of contaminants, but importantly these included the petroleum compounds benzene, toluene, ethylbenzene and the xylene isomers (BTEX), and some oxygenated hydrocarbons.  For the other classes of petroleum hydrocarbons and oxygenated hydrocarbons, there was either not a complete understanding of biodegradation processes or its confidence of success in an MNA-based remediation strategy. Since then greater knowledge has been gained particularly about methyl tertiary-butyl ether (MTBE) and polycyclic aromatic hydrocarbons (PAH).
  3. Biodegradation is recognised as the key natural attenuation mechanism for fuel hydrocarbons. To support the application of MNA, extensive compilations and reviews of BTEX biodegradation rates for laboratory and field sites are available, primarily based on studies from the United States.
  4. Australian data that might help define the scope of impact arising from the use of fuel additives (MTBE, ethanol and biodiesel) are scarce. The Australian experience of groundwater contamination from MTBE is likely to differ from the United States, as MTBE is potentially only present in fuels imported from overseas.
  5. Approaches for implementing MNA at sites contaminated with PAH are poorly developed compared with BTEX or chlorinated solvent sites. Knowledge about PAH degradation in the field and sorption/desorption processes is reasonably limited.
  6. There have been relatively few studies that have addressed the natural weathering of residual and mobile non-aqueous phase liquid (NAPL) fuels compared with studies into the processes affecting dissolved phase contaminants resulting from NAPL. This knowledge gap will be important where MNA is linked as a remedial strategy with NAPL clean-up.
  7. Groundwater recharge has recently been recognised as an important attenuation mechanism near the contaminant source. High-resolution multi-level sampling and scenario modeling are increasing our understanding in this area.
  8. Whether the assimilative capacity of an aquifer can be sustained over the multi-year life of a MNA remedial strategy is an area of knowledge that is poorly understood. One area of uncertainty relates to the longevity of cycling of redox-active elements (Fe, S) between the dissolved and mineral phases. Another is the prediction of changes in electron acceptors in response to changes in environmental conditions (e.g. recharge).
  9. Further knowledge about the expected value of particular biogeochemical indicator data to effectively discriminate contaminant degradation mechanisms at a fuel-impacted site is needed. This knowledge is needed to cost-effectively set up monitoring regimes capable of validating attenuation processes long-term.
  10. Published literature on natural attenuation processes at Australian sites for petroleum hydrocarbons is patchy and lacks a degree of specificity about site location, degradation rate and contaminant data, which therefore limits the usefulness of the literature for contributing to a generalised understanding of contaminant behaviour across those specific subsurface environments.
  11. In Australia, there have only been two published studies on petroleum hydrocarbon plume characteristics at multiple MNA sites. There is not enough data to conclude whether the generalised behaviour of petroleum hydrocarbon plumes under Australian conditions is similar to that reported from overseas. Therefore the general applicability of overseas data (e.g. degradation rates) to Australian sites is a knowledge gap.
  12. Published Australian natural attenuation literature has focused on shallow sand aquifer systems. These include the Quaternary aquifer around Perth and the Botany aquifer near Sydney. Studies on these sites could provide the fundamental data for scenario modelling at those locations. Generally, there were few papers which described contaminant behaviour in fractured rock and clay sites.

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Technical Report 02: Protocols and techniques for characterising sites with subsurface petroleum hydrocarbons - a review

Characterisation and monitoring of petroleum-impacted sites can be costly. Poor characterisation can lead to uncertain mapping of the mass and distribution of petroleum hydrocarbons in subsurface environments. This in turn can lead to poor decisions which may compromise human or environmental health or can increase costs where remediation is prolonged, misapplied or not well targeted due to lack of appropriate data.

Characterisation and monitoring of petroleum-impacted sites can be costly. Poor characterisation can lead to uncertain mapping of the mass and distribution of petroleum hydrocarbons in subsurface environments. This in turn can lead to poor decisions which may compromise human or environmental health or can increase costs where remediation is prolonged, misapplied or not well targeted due to lack of appropriate data.

From discussions between regulators, oil companies, consultants, CSIRO, CRC CARE and other researchers a scope of work related to site characterisation was developed. CRC CARE agreed to a review stage project proposal developed by CSIRO. The review stage is a first step in a larger project to document techniques and protocols that are used nationally and internationally – to bring greater unity and improved approaches to contaminated site assessment for petroleum impacts in soil and groundwater environments of importance to Australia.

This report:

  1. documents typical properties of hydrocarbon compounds and fuel/oil behaviours
  2. provides an overview of traditional staged and accelerated site characterisation strategies including a discussion of the Triad approach
  3. summarises available guidance, protocol and standards documentation from State government agencies and the NEPC, from industry, and from overseas (United States, United Kingdom, Europe, New Zealand)
  4. documents some standard and not so standard sampling and investigation techniques, and
  5. provides summary comment.

Important issues, protocols and technologies related to petroleum hydrocarbons in soil and groundwater environments are highlighted.

The review provides an introduction to the multiphase behaviour of petroleum hydrocarbons and the need to address gas, liquid and solid phases (air, water and soil) as well as the released non-aqueous phase liquid (NAPL) in site assessments – and to address both the vadose zone and groundwater. Fuels and oils are highly complex mixtures that change their composition over time. The intensity of investigative effort required in each phase is somewhat dictated by environmental and jurisdictional drivers, but also by typical properties of some petroleum hydrocarbons, which govern the likely distribution of the hydrocarbon product and individual compounds in the subsurface. A limited discussion of fuel additives is also given.

The importance of having site characterisation goals in a risk-based framework is emphasised – what is the overall goal and what is to be achieved at a site, what is the compliance point, and what phase is dominant? To assist with this, it is important to have a well developed conceptual site model, along with a targeted program of activity to improve the three-dimensional spatial and temporal understanding of petroleum contamination distributions in the subsurface. Such a program would be developed out of a full conceptualisation of the site model – inclusive of hydrogeology and soil strata, primary fuel/compound types, the presence of additives, compliance boundaries, principal transport mechanisms in each phase, the proximity of receptors, etc. The intensity of effort can be refined using data quality objectives, where ‘data quality’ may more generally refer to data that adequately represents the site conditions. It is concluded that an investigation program needs to be purposeful, adequate and representative to achieve its aims (i.e. on PAR).

The traditional staged approach to site characterisation (Phase 1 and Phase 2 environmental site assessments – ESAs) is compared with accelerated site characterisation (ASC) and in particular the so-called ‘Triad’ approach, which links systematic planning and dynamic work strategies with on-line and on-site measurement techniques to enable site characterisation in a (hoped for) single mobilisation. No implementation of ASC techniques is apparent in Australia, despite savings estimates of up to 40–50% for some applications in the United States of America.

Information on some of the standard and more novel site characterisation technologies is reviewed, including direct push technologies, geophysics, on-site analytical techniques, NAPL characterisation, capillary fringe and vadose zones, combined technologies, directional and alternate drilling, flux estimation techniques, passive and on-line sampling/monitoring devices, and reactive transport modelling. Further development, validation and combination of technologies is required if rapid and cost-effective site characterisation is to have greater adoption in Australia.

Summary observations from the review include:

  1. A risk-based approach should be taken as the starting point for site characterisation, since this forces consideration of the regulatory regime, exposure pathways, and focuses effort on establishing a robust conceptual model – with field investigations that target the improvement and modification of this model.
  2. A clear information objective is important – embodying data quality objectives and achieving representative sampling of a site.
  3. Important to any site characterisation is the derivation of a site conceptual model that integrates what is already known about a site, and identifies both what still needs to be discovered, and how that information should be used.
  4. Choices of site investigation approaches should be made on the basis of improvement of the site conceptual model. The site conceptual model also serves as the basis for risk assessment and remediation. The information needed for risk assessment and remediation planning is not necessarily the same.
  5. Site characterisation plans need to be flexible and adaptable to allow feedback on possibly real-time results. This kind of dynamic approach to site characterisation needs to be considered as a part of overall site investigation strategy, before site characterisation mobilisation. It also impinges on the reliance on conventional sample to laboratory systems, as laboratory data can take longer to be generated. Dynamic approaches may also need to encompass remediation planning.
  6. If representivity is to be emphasised, perhaps the analytical precision of conventional laboratory (off-site) analyses could be traded off against greater data intensity on-site, especially when comparing sources of error from sampling, and sources of uncertainty from site heterogeneity and variability.
  7. For groundwater investigations, guidance documents generally promote a minimum of three or four boreholes. In practice, on average a greater number of sampling boreholes is used. Greater use could be made of statistical sampling theory, statistical tests of significance, and geostatistical analysis to handle aquifer and geochemical heterogeneity.
  8. Site investigation data needs to be assessed over time, as well as in space, so that trends in contaminant behaviour can be assessed. The depth dimension is often neglected in air, water and soil phases. Whilst depth sampling of soils/sediments (whether in the vadose zone or groundwater) is mentioned in several guidance documents – it has not been formalised. Depth discrete sampling of groundwater is mostly ignored.
  9. A variety of site characterisation techniques are available for on-site analyses, from on-site sensors to geophysical techniques. Validation and improvement is required to avoid false negative and positive outcomes, and to build reliability and confidence into rapid assessment practices.
  10. Development of new tools for on-site use in site characterisation is increasing – but if ASC or Triad is to be pursued, further development of new or novel sensor and site characterisation techniques should be pursued – especially those that would allow rapid on-site decision making and achieve reliable outcomes at reduced cost. Combining ‘continuously available’ data with models on-line could also be pursued. This is near-readily available for groundwater flow, however, where geochemistry and reactive transport is important on-line real-time linkages between data collection and models is problematic due to the computational intensity of such codes.
  11. The use of ‘direct push’ tools as opposed to conventional drilling, and a variety of attachments and sensors which can be used with these direct push tools to collect site investigation information is desirable. This allows more real-time information gathering and implementation of dynamic site characterisation strategies. Innovation in this area should be encouraged.
  12. In Australia, implementation of Triad would require upskilling of all elements of site characterisation (planning, on-site interpretation including sophisticated modelling, and technology availability and deployment) in consulting agencies and/or industry, and integration of these skills with the regulatory approvals process – possibly on-site.
  13. Harmonisation of the regulation of site characterisation through NEPM or other mechanisms may assist the practice of site characterisation, but reduced flexibility needs to be avoided to allow for continued innovation.
  14. Greater guidance on the use and application of numerical models to integrate site characterisation data could be useful. The Murray-Darling Basin Commission issued guidelines for water resource groundwater flow modelling in 2000. Prommer et al. (2003) provided an initial basis for petroleum plumes in groundwater. There are no Australian guidelines for modelling multiphase hydrocarbon behaviour.
  15. There is a need to continue to facilitate knowledge transfer across regulators, contaminated site owners, service providers and the academic community.
  16. The scalability of site investigation plans and technologies should be assessed – from UST and service station scale, to depot and terminal scale and perhaps refinery or multiple source complex mega-site scale.
  17. US documentation (ASTM, API, etc.) includes management as part of guidance in many instances, whilst the NEPM does not. Interestingly, the NSW EPA Service Station guidelines did include remediation options as part of the guidance. A perceived difficulty in embedding management options in such guidance is the lack of stability in the range of technologies on offer.
  18. Research and innovation is needed to quantify and optimise the value of gathering additional data so as to minimise uncertainty during assessment – to provide more precise definition of risks and costs for clean-up applications. For example, whilst the multiphase behaviour of petroleum hydrocarbons is recognised, the value of extra data in any one phase in reducing uncertainties in risk assessment or the selection of remedial options is not well defined.

A number of challenges remain – none the least of these is maintaining flexibility to adopt new ideas and technologies and, where needed, change the regulatory and industry norm to allow alternative assessments, whilst maintaining protection of human health and the environment.

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