guidelines for consideration of sustainability in

December 2010

guidelines forconsideration of sustainability in remediation of contaminated sites

http://www.defence.gov.au/dsg/index.htm

Department of DefenceNational Contamination Remediation Program Directorate of Environmental Impact Management Email: [email protected] Phone: (02) 6266 8058

© Commonwealth of Australia 2010.

This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Commonwealth.

Defence Publishing Service, Corporate Graphics – DPS OCT015/10

Contents

ExEcutivE Summary iii

1. introduction 11.1 Background 1

1.2 Objective 1

1.3 Scope of this Document 1

2. SuStainablE rEmEdiation FramEwork 22.1 Definitions 2

2.2 Key Principles 2

2.3 Alignment with Australian Regulatory Authorities 3

3. aPPlication oF thE FramEwork 43.1 Link to Defence Strategy for Management of Contaminated Land 4

3.2 Defence Property Life Cycle Points at which to Consider Sustainability 5

4. rEmEdiation SuStainability Evaluation 64.1 Sustainability in the Broader Remediation Options Assessment Phase 6

4.2 Sustainability Assessment 7

4.2.1 Environmental Impacts 8

4.2.2 Social Impacts 8

4.2.3 Economic Impact 8

4.3 Relationship to Source, Pathway and Receptor Controls 9

4.4 Sustainability of Remediation Technologies 10

4.5 Sustainability of Remediation Technologies 10

4.6 Sustainability Assessment Tools 11

5. caSE StudiES 12 5.1 Case Study 1 – Heavy Metal Contamination on Proposed Residential Development 12

5.2 Case Study 2 – LNAPL Impacts at a Fuel Farm 14

5.3 Case Study 3 – Options to Remediate PAH Contamination at a Residential Development 16

FigurE indEx Figure 1 – Remediation Options Decision Tree 7

aPPEndicES A Remediation Technology Sustainability Considerations 18

Section Title to go here

Executive Summary

the application of sustainability principles in the context of contaminated land management and remediation is widely encouraged by defence and is consistent with the defence contamination management Strategy (dcmS). australian regulatory authorities have also shown growing support for the principles of sustainability in contamination management, driven largely by the adoption of risk-based approaches to contamination issues, and an emphasis on the sustainable use of resources and energy in recognition of climate change.

this guideline is intended for use by Project development and environmental managers and their consultants who are responsible for making decisions regarding works and the remediation of defence sites. it outlines the defence framework for implementation of sustainability principles in contamination management including identification of the key property life cycle points at which to consider sustainability, and a framework for the consideration of sustainability in the broader contamination management options assessment process. the concepts have been drawn from the framework being developed by the Sustainable remediation Forum (SurF) australia.

the definition of sustainable remediation adopted by defence is based on there being an acceptable balance in terms of environmental, social and economic outcomes in undertaking a remediation activity, and the benefits that the remediation will deliver. remediation is considered in the context of actions to assess or break source-pathway-receptor linkages, thereby managing risks associated with the presence of contaminants in the environment.

application of the principles of sustainability to defence remediation projects should occur at two stages. at the land use and development planning phase there is an opportunity for designation of specific land uses taking into account the contamination status of the land so that the resources required for remediation may be minimised. during the remediation strategy planning phase, sustainability is to be considered in selection of an approach that seeks to balance the net environmental, social and economic benefit, and the extent to which clean-up or management is required in light of the contamination risk.

a broad remediation options assessment framework is presented that outlines the key requirements for contamination management to be met prior to evaluation of the sustainability of a remediation approach. an emphasis is placed on first establishing the options that will effectively achieve source – pathway – receptor control as well as meeting the mandatory requirements of stakeholders and regulators. the sustainability of each option from an environmental, social and economic perspective must then be considered to establish the net benefit of each option. Quantitative methods are available for comparisons between options such as energy usage and financial considerations. For other factors such as potential social impacts / benefits a qualitative evaluation will be more appropriate.

the united States Environmental Protection agency has defined management of contamination that seeks to minimise the environmental and energy footprint as ‘green remediation’. defence also supports this concept which seeks to maximise the net environmental benefits of remediation by taking into consideration energy requirements, air emissions, water consumption, land and ecosystem impacts, material consumption and long term stewardship. this document also provides some examples of the environmental, social and economic aspects to be considered for a range of remediation technologies.

Finally, three defence case studies are presented that seek to highlight the wider scope of thought that is to be applied to the evaluation of remediation options, taking into consideration the environmental, social and economic benefits and dis-benefits that may ensue. the level of assessment required at this stage and the complexity of evaluation methods applied have to be commensurate with the size and nature of the project.

IIIDepartment of Defence Guidelines for Consideration of Sustainability in Remediation of Contaminated SitesCONTENTS • PRINT

1Department of Defence Guidelines for Consideration of Sustainability in Remediation of Contaminated Sites

1.

Introduction

1.1 background

The sustainable use of resources and assets and the sustainable

management and development of land are core components

of the Defence Contamination Management Strategy (DCMS). The

application of sustainability principles in the context of contaminated

land management and remediation is widely encouraged by Defence

and regulatory agencies. While largely driven through concerns

regarding climate change, the principles are also aligned to other

Defence policies concerning wise use of resources.

1.2 objEctivE

These guidelines are intended for use by Defence environmental

managers and their consultants who are responsible for making

decisions regarding works and the management and remediation of

contaminated sites. Key decision points in the Defence property life

cycle have been identified at which the principles of sustainability is

to be considered in the context of contaminated land.

Many of the concepts contained within this document

have been drawn from the framework being developed by

the Sustainable Remediation Forum (SuRF) Australia1 and

adapted for use by Defence.

1.3 ScoPE oF thiS documEnt

This document outlines the Defence framework for implementation

of sustainability principles in contamination management. It provides:

1. A definition of sustainability and the key principles of sustainable

remediation and management of contaminated sites;

2. An overview of the application of the principles of

sustainability to Defence contaminated land projects

including identification of the key property life cycle points

at which to consider sustainability;

3. A framework for the consideration of sustainability in the broader

contamination management options assessment process; and

4. Three case studies to demonstrate how the principles

of sustainability may be incorporated into the remediation

options assessment process.

1 Sustainable Remediation Forum Australia 2009, ‘A framework for assessing the sustainability of soil and groundwater remediation – initial working draft’ Sustainable Remediation Forum Australia, August 2009.

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2 Department of Defence Guidelines for Consideration of Sustainability in Remediation of Contaminated Sites

2.

Sustainable Remediation Framework

2.1 dEFinitionS

Sustainable development has been defined as development that

meets the needs of the present generation without compromising

the ability of future generations to meets their own needs2. This

has been further interpreted as taking actions that will result in

optimisation of net environmental, social and economic benefit3.

Defence supports the definition of remediation as: ‘actions

to assess or break a source-pathway-receptor linkage

and thereby manage risks associated with the presence

of contaminants in the environment’.

Sustainable remediation has been defined by SuRF UK as: ‘the

practice of demonstrating, in terms of environmental, economic

and social indicators, that an acceptable balance exists between

the effects of undertaking remediation activities and the benefits

that those activities will deliver’.4

2.2 kEy PrinciPlES

The key principles of sustainable remediation are:

1. Protection of human health and the environment

through removal of unacceptable risks;

2. Safe work practices to protect workers, the community

and the environment;

3. The achievement of net-benefit through balanced

consideration of environmental, social and economic factors

as well as the principles of intergenerational equity and the

precautionary principal;

4. Documentation of the remediation decision process

to clearly record the assumptions and data used to reach

the final remediation/ management strategy;

5. Good Governance and Stakeholder Involvement.

The needs of all stakeholders must be identified and considered

and the decision making process well documented; and

6. Sound Science. The remediation strategy must be based

on sound scientific principles using relevant and accurate data

and well documented assumptions.

2 United Nations, Report of the World Commission on Environment and Development, 4 August 1987.3 Sustainable Remediation Forum Australia 2009, ‘A framework for assessing the sustainability of soil and groundwater remediation

– initial working draft’ Sustainable Remediation Forum Australia, August 2009.4 Sustainable Remediation Forum UK 2010, ‘A framework for assessing the sustainability of soil and groundwater remediation, March 2010.

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Section Title to go here


These principles are to be considered at the remediation options and

feasibility stages, but are also relevant during the initial planning and

investigation stages where decisions regarding proposed land use

and the nature and level of data collection are made. For a particular

project scenario it will be necessary to identify which of the key

principles are mandatory vs those that are subordinate in so far as

they are desirable but not mandatory.

2.3 alignmEnt with auStralian rEgulatory authoritiES

Australian regulatory authorities have shown growing support for

the principles of sustainability in contamination management. This

has largely been through the adoption of a risk-based approach

based on ‘suitable for certain use’ and ‘source-pathway-receptor

control’ principles of remediation5. Furthermore, there has been

recognition by regulatory authorities that full clean up and restoration

of contaminated land to its original condition is not always feasible

and may place an unfair and unwarranted burden on the community.

More recently, the recognition by Government that climate change

is occurring has placed new emphasis on the sustainable use

of resources and energy.

5 Nadebaum, P 2009, ‘Sustainable management of contaminated sites: what can this mean for Defence and what are the implications?’ paper presented at EcoForum, Adelaide, 28-30 April 2009.

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3.

Application of the Framework

Application of the principles of sustainability to Defence

contaminated land projects should occur at two stages:

1. Land use and development planning phase:

When planning for the long term development of Defence

land, designation of specific land uses must be done with

consideration of the contamination status of the land so that

the resources required for immediate or future clean up or

management are minimised. For example, the placement of

sensitive land use developments such as residential areas on

clean, uncontaminated or ‘green-fields’ land, and potentially

contaminating activities (such as industrial processes) on land

that has historically been used for similar or related activities.

2. Remediation or management strategy planning phase:

The remediation options stage is to consider sustainability both

in the selection of an appropriate technology that seeks to

balance net environmental benefit, and the extent of clean-up or

management required in light of the actual risk of contamination

and sensitivity of the site’s proposed end use. Sustainability

is to also be considered during site ivestigation. This includes

the actual resources required for the investigation, as well as

the level and nature of assessment required to make informed

decisions regarding a sustainable solution.

3.1 link to dEFEncE StratEgy For managEmEnt oF contaminatEd land

Under the Defence Environmental Policy, Defence’s environmental

vision is that: “Defence will be a leader in sustainable environmental

management to support the Australian Defence Force’s capability

to defend Australia and its national interests”6. Under the Defence

Environmental Strategic Plan 2010 – 2014, Defence’s environmental

strategic plan for contaminated land includes the goal:

Goal 1 – Contamination Management – Contamination legacy

on Defence land reduced over the life of the strategic plan.

The DCMS is based on applying the principles of risk management,

and emphasises the sustainable use of resources and assets

and the sustainable management and development of land

and groundwater.

6 Department of Defence, Defence Environmental Strategic Plan 2010-2014.

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3.2 dEFEncE ProPErty liFE cyclE PointS at which to conSidEr SuStainability

Table 1 lists the specific points in the Defence property life cycle

where decisions can be made to optimise the sustainability of the

contaminated land management or remediation solution.

Table 1 – Defence Property Life Cycle Points at Which to Consider Sustainability

Phase activity actions to Support Sustainable remediation

Site / project development and planning

Property procurement The level of clean-up required for land to be made suitable for its intended use is considered as part

of the pre-purchase due diligence process.

Defence estate spatial (land-use) planning Inclusion of potential contamination issues as a factor in decisions regarding allocation of land for

particular uses.

Base planning Base planning to consider the nature and spatial distribution of any contamination and, based on

the implications, adjustment of the development plan.

Property disposal Consideration of the resources required for restoration of land to allow disposal, vs continued

ongoing use by Defence.

Remediation options assessment

Remedial and management strategy design A focus on risk based remediation strategies that aim to break source-pathway-receptor linkages to

reduce contamination risk to an acceptable level.

Remediation technology selection Selection of a remediation technology that achieves the risk-based remediation goals while

achieving an environmental, social and economic net-benefit.

Selection of ‘green technologies’ as part of the remediation system design, such as processes

designed for optimum efficiency and use of renewable energy sources.

Site investigation activities

Design of site characterisation and remediation

verification strategies

Investigations to target the development of a robust source-pathway-receptor conceptual site model

upon which to base a risk-based remediation strategy.

Implementation of site characterisation and

remediation verification strategies

Environmental management measures to reduce impacts to the environment from investigation

activities.

At each point in Table 1, the priority must be in establishing if a

particular remediation option meets the remediation objectives and

the mandatory requirements of the relevant stakeholders. Once it

has been established that these will be met, consideration of the

sustainability of each action must be made through review of the

environmental, social and economic costs and benefits.

In deciding on a remediation approach, the emphasis must be in

the establishment of the most important requirements to be met,

and ensuring that these are dealt with, prior to more subordinate

objectives which may be desirable but not essential.

Application of the Framework

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4.

Remediation Sustainability Evaluation

This section provides an outline of where consideration of sustainability is to occur during the evaluation of remediation options. It also provides a qualitative framework for the assessment of the sustainability of remediation actions in the context of environmental, social and economic net benefit. It is intended to provide guidance for the planning and options assessment stage. It is not intended to detail the full remediation options assessment process, which is beyond the scope of this document and will vary depending on the nature of the project and contamination scenario.

4.1 SuStainability in thE broadEr rEmEdiation oPtionS aSSESSmEnt PhaSE

The initial consideration of remediation sustainability have to be

made at the project inception and feasibility stages. It is during this

early stage that broad decisions can be made to amend the project

/ development plan to reduce or avoid the need for potentially costly

remediation. For example, a change in the development plan to

move a building away from the site of a hydrocarbon plume may

reduce the extent to which groundwater clean-up is required, or the

need for vapor barriers in the building design.

If remediation or management of contamination is required, the

potential remediation options should be broadly established followed

by three critical stages of evaluation:

Stage 1

Establishment of the options that will effectively

achieve source – pathway – receptor control. This may

require a technology review and detailed consideration

of the conceptual site contamination model in the context

of the site’s current and future use.

Stage 2

Establishment of the mandatory requirements of

each stakeholder that must be met for the project, and

confirmation that these can be met for each remaining

option from Stage 1. For example, the option must

achieve regulatory compliance, but may also need to

meet the requirements of community groups, which may

not be immediately apparent. An essential element of

the stage is to apply the Defence Contamination Risk

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Assessment Tool (CRAT) to the circumstances of the site

that will apply after remediation to determine if the option is

acceptable to Defence.

Stage 3

For options that satisfy Stage 1 and Stage 2, an

evaluation to determine whether an acceptable balance

exists between the effects of undertaking remediation

activities, and the benefits that those activities will deliver.

It is at this stage that sustainability indicators are to be used

to assess the remaining options in relation to the goal for

achievement of environmental, social and economic net

benefit (Refer Section 5.2).

This process is set out in the decision tree shown in Figure 1.

4.2 SuStainability aSSESSmEnt

The third stage of the remediation options assessment process

(Figure 1) is appraisal of the sustainability of selected remediation

or management options. This is where the environmental, social

and economic net benefit of the remediation option must be critically

established. A set of environmental, social and economic indicators

against which to assess the net-benefits of remediation may be

assessed are outlined in Table 2.

The detail given to the assessment are to be proportionate to the

issue and magnitude of the remediation or management response

that may be required. For example, a qualitative evaluation may

be sufficient for a small remediation project such as a limited

groundwater plume, whereas larger scale projects involving large

quantities of contaminated media would warrant a more detailed

and quantitative evaluation including cost benefit analysis.

Figure 1 – Remediation Options Decision Tree

Revise project/development plan

Amend

Yes

Yes

Yes

Yes

No

No

No

No

Can the project/development plan be amended to prevent/reduce the need for remediation/management

of contamination?

Remediation/contamination management options

Will the option achieve effective resource – pathway – receptor control?

Task: technology review

Selection or shortlist of option(s) leading to feasibility stage or pilot trial.

Does the option achieve a balance between environmental, social and economic net benefit?

Task: sustainability assessment

Will the option meet the mandatory requirements of all stakeholders? What are critical requirements to be

met those that are merely desirable?

Task: CRAT outcomes, regulatory review and stakeholder engagement

STAgE 3

STAgE 2

STAgE 1

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Table 2 – Sustainability Assessment Indicators7

Environmental Social Economic

1. Impacts on air; 1. Impacts on human health and safety; 1. Direct economic costs and benefits;

2. impacts on soil; 2. Ethical and equity considerations; 2. Indirect economic costs and benefits;

3. impacts on water; 3. Impacts on neighborhoods or regions; 3. Employment and capital gain;

4. Impacts on ecology; 4. Community involvement and satisfaction; 4. Gearing;

5. Use of natural resources and generation of wastes; and 5. Compliance with policy objectives and strategies; and 5. Life-span and ‘project risks’; and

6. Intrusiveness. 6. Uncertainty and evidence. 6. Project Flexibility.

Environmental, social and economic impacts of remediation and contamination management are broadly discussed below:

4.2.1 Environmental impacts

Consideration of the net environmental impact must take in account

both the local and global environments:

The net impact to the local environment from remediation are to

almost always be positive, however local factors to consider that

may be negative include impacts to adjacent land from disturbance

of contamination, impacts from assessment activities, and byproduct

discharges. These local impacts are to be balanced against the

reduction in contamination risk and restoration of beneficial use

of the land that the remediation seeks to achieve.

The inclusion of ‘green technologies’ in the remediation strategy

offers another avenue for achieving environmental net benefit.

Consideration is to be given to: use of renewable energy sources

(e.g. solar energy to power a groundwater pump-and-treat system);

recycling and re-use of by products (e.g. re-use of solid inert wastes

as construction materials, or creation of energy from methane gas);

efficiency optimisation; and water conservation (e.g. storm-water

runoff controls and water recycling).

As active remediation will typically involve the use of resources

and energy, the global environmental impacts from remediation

including energy use and CO2 emissions are likely to be negative.

In most cases the emphasis here will be on minimisation of impacts.

The exception to this may be in circumstances where resource or

energy recovery is incorporated into the remediation response such

as recycling of wastes and generation of energy from by-products.

These impacts have to be measured by taking into consideration

energy consumption, tonnes of resources consumed, and

wastes generated.

4.2.2 Social impacts

A core focus for the remediation will be to reduce to an

acceptable level the risk of adverse impact from contamination

to site occupants and the public. This will typically be quantified

through risk assessment or direct measurement at the receptor.

Similar to local environmental impact, this factor must have a net

positive impact for the remediation approach to be successful and is

to be considered during Stage 1 of the remediation evaluation

process (Figure 1). Occupational health and safety of site workers

involved during the construction process and earlier investigation

phases may represent negative impacts, although procedures to

minimise exposure of workers to contaminants are now generally

well established.

Stakeholder concern – or the acceptability of the remediation

response – is an important factor to be addressed as part of Stage

2 of the remediation options evaluation process, and can form

an important part of the social dimension. Stakeholder liaison is

essential where there is a linkage between the remediation works

and the public, and can assist in establishing and balancing

concerns that the public might have. Quantification of social impacts

may be difficult and is likely to involve a qualitative evaluation and

simple ‘yes’/‘no’ response to the achievement or otherwise of

stakeholder objectives.

The social dimension must also take into consideration the

impact on the amenity of the surrounding area during and after

remediation. It is likely that negative impacts to the surrounding

land and community during a construction phase will be followed

by positive impacts as the beneficial uses of the land are restored.

4.2.3 Economic impact

Procedures for quantifying or estimating the financial

costs of remediation projects are well documented. Cost is

an essential aspect of the feasibility of remediation options,

and must be considered throughout the various stages of

the options assessment.

7 Sustainable Remediation Forum UK 2010, ‘A framework for assessing the sustainability of soil and groundwater remediation, March 2010.


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The sustainability evaluation must interrogate further the economic

impact of the remediation by taking into account the potential

ongoing or future financial costs of the approach. The financial risk

associated with project uncertainties as well as a life-cycle analysis

of the proposed option must be considered. Positive economic

impacts such as direct and indirect benefits to the economy and

employment are other important considerations.

Table 3 – Implications of Sustainability Considerations8

nature of control Environment Social Financial key issues

Source Removal Positive aspects:

• Higher level of certainty that the contamination will not pose a concern in the future;

• Higher level of certainty that regulatory environmental issues will be met.

Negative aspects:

• Higher consumption of resources (energy, landfill, labour);

• Risk to environment associated with remediation work.

Positive aspects:

• Higher level of certainty that the site will be safe;

• Short time frame;

• No future liability for future generations.

Negative aspects:

• Higher level of risk to workers and the public in vicinity while the remediation works are carried out;

• Uncertainty regarding future safety of the site.

Positive aspects:

• Avoids long term monitoring and control;

Negative aspects:

• Higher level of cost.

Is it practicable to remove the source to the required level?

Is achieving resolution in a short time frame essential?

Pathway Control Positive aspects:

• Lower consumption of resources;

• Lower risk to the environment associated with remediation work.

Negative aspects:

• Reliance on long term controls;

• Higher level of uncertainty that long term safety will be achieved.

Positive aspects:

• Lower level of risk to workers and the public in vicinity as can avoid remediation work;

Negative aspects:

• Lower level of certainty that site will be safe;

• Longer time frame over which controls need to be applied;

• Higher level of risk to Defence;

• Continuing liability;

• Higher level of uncertainty regarding future safety of the site.

Positive aspects:

• Lower level of cost.

Negative aspects:

• Long term ongoing cost for management and monitoring.

Is the time frame acceptable?

Will it provide an acceptable level of risk to Defence?

Will it be acceptable to the regulatory authorities?

Will it provide for adequate protection of groundwater?

Receptor Control Positive aspects:

• Lower consumption of resources.

Negative aspects:

• Restricted future use of the site;

• Higher risk that adjacent land and groundwater might be affected.

Negative aspects:

• Restricted future use of the site.

Positive aspects:

• Lower level of cost.

Will it provide an acceptable level of risk reduction to Defence?

Will it unacceptably limit land use and Defence capability in the long term?

Will it be acceptable to the regulatory authorities?

4.3 rElationShiP to SourcE, Pathway and rEcEPtor controlS

Each remediation option may have significantly different social,

environmental and economic implications. Examples of positive

and negative aspects of the three broad approaches to remediation

– source removal, pathway control and receptor control – are shown

in Table 3.

8 Nadebaum, P 2009, ‘Sustainable management of contaminated sites: what can this mean for Defence and what are the implications?’ paper presented at EcoForum, Adelaide, 28-30 April 2009.


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4.4 alignmEnt with thE PrinciPlES oF SuStainablE dEvEloPmEnt

The following principles of sustainable development are relevant

to site remediation in the context of the processes and activities

to achieve remediation, and the outcomes and benefits that the

remediation seeks to deliver:

• Integration of economic, social and

environmental considerations;

• The precautionary principle;

• Intergenerational equity;

• Conservation of biological diversity and ecological integrity;

• Improved valuation, pricing and incentive mechanisms;

• Shared responsibility;

• Product stewardship;

• The wastes hierarchy;

• Integrated environmental management;

• Enforcement; and

• Accountability.

The achievement or otherwise of the above for each

considered option is to be systematically considered

as part of the sustainability evaluation process.

4.5 SuStainability oF rEmEdiation tEchnologiES

There are many opportunities to maximise the net environmental,

social and economic outcomes of remediation projects by selection

of particular technologies, or enhancement of technologies such as

through use of renewable energy sources, or inclusion of processes

that promote recycling and waste recovery. The management of

contamination that seeks to minimise the environmental and energy

footprint has been referred to as ‘green remediation’. The following

aspects of the remediation process have to be considered when

seeking to optimise the net environmental benefits of remediation7:

Energy requirements of the treatment system:

• Where possible use passive-energy technologies that do not

have external power requirements;

• Select energy efficient equipment where external power sources

are required, and maintain equipment and configure system to

optimise efficiency; and

• Where possible, use renewable energy systems such as solar

power instead of mains electricity.

Air emissions:

• Minimise the use of heavy equipment requiring high

volumes of fuel;

• Use cleaner fuels and retrofit diesel engines to operate

heavy equipment, when possible;

• Control emissions to reduce atmospheric release of greenhouse

gases; and

• Minimise generation of dust that may transport contaminants.

Water requirements and impacts on water resources:

• Minimise the use of fresh water and maximise water reuse

during daily operations and treatment processes;

• Recycle treated water for beneficial use such as irrigation;

• Use native plants for re-vegetation that require little or

no irrigation; and

• Put in place measures to prevent impacts such as nutrient

loading on water quality in nearby water bodies.

Land and ecosystem impacts:

• Prioritise the use of minimally invasive in situ technologies;

• Use passive energy technologies such as bioremediation as

primary technologies or “polishing steps,” where possible;

• Minimise soil and habitat disturbance;

• Minimise bioavailability of contaminants through adequate

contaminant source and plume controls; and

• Reduce noise and lighting disturbance.

Material consumption and waste generation:

• Use technologies designed to minimise waste generation;

• Re-use materials whenever possible;

• Recycle materials generated at or removed from the site

whenever possible;

• Minimise natural resource extraction and disposal; and

• Use passive sampling devices producing minimal waste,

where feasible.

7 United Stated Environmental Protection Agency (USEPA) Office of Solid Waste and Emergency Response 2008, ‘Green remediation: incorporating sustainable environmental practices into remediation of contaminated sites’ USEPA, April 2008.


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Long term stewardship actions:

• Reduce emission of CO2, N2O, CH4, and other greenhouse

gases contributing to climate change;

• Integrate an adaptive management approach into long-term

controls for a site;

• Install renewable energy systems to power long-term cleanup

and future activities on redeveloped land;

• Use passive sampling devices for long-term monitoring, where

feasible; and

• Solicit community involvement to increase public acceptance

and awareness of long-term activities and restrictions.

Appendix A provides a summary of widely used remediation

technologies, and some of the key environmental, social and

financial factors to be considered for each.

4.6 SuStainability aSSESSmEnt toolS

A variety of sustainability assessment tools are available for land

and groundwater remediation projects. These are both qualitative

and quantitative and are based on an assessment of individual

indicators similar to those listed in Table 2. Examples of such are

provided in Ellis & Hadley (2009) and have been listed below:

• Life-Cycle Assessment (General).

• Air Force Centre for Engineering and the Environment

– Sustainable Remediation Tool.

• URS/DuPont Sustainability Assessment Tool.

• GolderSET-SR-CN Sustainability Tool.

• Minnesota Pollution Control Agency (MPCA) Green Practices

for Business, Site Cleanups: A Toolkit.

• The REC Decision Support System for Comparing Soil

Remediation Alternatives (Dutch Research Program for

In Situ Bioremediation).

• Shell Cost-Benefit Analysis (United Kingdom).

• Swedish Hallbar Sanering cost-benefit analysis/life-cycle

analysis model.

The above is not an exhaustive list, and it is strongly recommended

that a review of available assessment tools be made prior to

embarking on an evaluation. In particular, the tool selected is

to be appropriate to the nature and significance of the project.

Some tools allow such flexibility, for example, the Air Force Centre

for Engineering and the Environment (AFCEE) – Sustainable

Remediation Tool (SRT) allows for Tier 1 and Tier 2 assessments

to be made. A Tier 1 assessment is undertaken where a quick

evaluation is required and detailed information is unavailable. A Tier

2 Assessment is appropriate for larger projects where more detailed

inputs are available and greater certainty is sought. It is also possible

that more that one sustainability assessment tool may be required

for various components of a project.


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5.

Case Studies

The following case studies demonstrate how the principles of sustainability may be incorporated into the remediation options assessment process for Defence projects. The sustainability questions posed represent Stage 3 of the broad remediation options assessment framework set out in Figure 1. The case studies are intended to provide an overview of the types of questions that have to be asked during this stage of the assessment process. They do not represent completed sustainability assessments which are expected to be more detailed, commensurate with the size and complexity of the project, and involving a quantitative component using a tool such as that described in Section 4.5.

5.1 caSE Study 1 – hEavy mEtal contamination on ProPoSEd rESidEntial dEvEloPmEnt

Defence is intending to construct a residential accommodation

facility on a disused portion of land on a RAAF base. The land

was historically used by RAAF for metal working activities, which

included sandblasting and metal cleaning. The industrial buildings

formerly housing these activities have since been demolished. The

development is to comprise a series of freestanding residential

buildings with adjoining lawn and garden areas. The accommodation

will be used by house Defence personnel and their families.

An environmental assessment has revealed the presence of heavy

metal contamination in the shallow soil profile that exceeds National

guidelines for the site to be suitable for residential use. It has been

estimated that there is approximately 2,000 m3 of soil that is

contaminated. Currently there are no technically feasible on or off-

site methods for treating the soil to reduce total concentrations. A

landfill that will accept the soil is located approximately 100 km from

the site.

The site is the optimum location for the development because of its

proximity to other site facilities. There are other areas of the base that

have never been used for an industrial purpose, but these are further

away from the site’s main mess buildings and amenities and would

involve longer commuting by site occupants.

Following a risk assessment using the Defence Contamination Risk

Assessment Tool (CRAT) and process of stakeholder engagement,

the following options have been found to be generally acceptable

to all stakeholders:

OPTION 1 Excavate the contaminated soil and dispose of off-site

to a landfill – source removal;

OPTION 2 Modify the development plan to include paved areas

and barrier layers to limit the potential for contact of site occupants

with contaminated soils – pathway control; or

OPTION 3 Relocate the residential development to a ‘green-fields’

portion of the site, and use the former industrial site for a less

sensitive use in the future – receptor control.

CONTENTS • PRINT


Case Studies

Table 4 outlines some of the potential environmental, social and financial sustainability considerations for each option.

Table 4 – Case Study 1- Residential Development

option Environment Social Financial

OPTION 1

Excavate the contaminated soil and dispose of off-site to a landfill

(Source removal)

Positive

• Higher level of certainty that the contamination will not pose a threat to the environment on-site (e.g. leaching to groundwater or impact to flora and fauna).

• Easier to achieve regulatory approval or auditor sign-off.

• Higher levels of certainty that site users will not come into contact with the soil contamination.

• No requirements for on-site management of the soil contamination into the future.

• Avoids the costs associated with modification of the development plan.

• Avoids the cost associated with ongoing management of capping layers or other site management measures.

Negative

• High energy use and CO2 emissions required for excavation and transport of contaminated soil.

• Environment risks associated with earthworks and transport of contaminated soils.

• Higher level of risk to workers (e.g. direct contact) and site users (e.g. dust inhalation) during the remediation works as a result of disturbance of the contaminated soils.

• High cost associated with excavation, transport and off-site disposal of contaminated soils, and importation and compaction of clean fill.

OPTION 2

Containment of the contamination by modifying the development plan to include paved areas and soil barrier layers

(Pathway control)

Positive

• Lower consumption of resources and generation of CO2.

• Less likely to impact other parts of the environment by shifting contamination.

• Reduction in risk to workers during construction as soil contamination remains undisturbed.

• Averting the need to excavate, transport and dispose of contaminated soil may represent a significant cost saving during the development phase.

Negative

• Higher level of uncertainty that groundwater or storm-water will not be impacted from leaching of heavy metals from soils.

• Increase in risk to workers that may come into contact with soil contamination during maintenance and/or installation of underground services in the future.

• Potential for breach of soil barriers in the future.

• Higher level of uncertainty regarding the adequateness of the barrier.

• The burden of ongoing maintenance and responsibility for contamination management.

• Soil contamination represents a continuing liability to Defence.

• Cost of ongoing maintenance of the barrier layer.

OPTION 3

Relocate the residential development to a ‘green-fields’ site and use the land for a less sensitive use

(Receptor control)

Positive

• Lower consumption of resources and generation of CO2 during the construction phase.

• Less likely to impact on other parts of the environment by disturbing and transporting contamination.

• Reduction in risk to workers during construction phase as soil contamination remains undisturbed.

• Averting the need to excavate, transport and dispose of contaminated soil may represent a significant cost saving during the development phase.

Negative

• Higher level of uncertainty that groundwater or storm-water will not be impacted from leaching of heavy metals from soils at the original site.

• Alternative ‘green-fields’ site is further from other amenities resulting in ongoing higher consumption of resources and generation of CO2.

• Environmental degradation of the alternative ‘green-fields’ site.

• Loss of amenity for site occupants due to increased distance to other amenities from alternative ‘green-fields’ site.

• Restricted future use of the contaminated site.

• Less sensitive use of the contaminated site may not be consistent with the surrounding landuse.

• Potential for contamination at the original site to impact on surrounding land.

• Increase in risk to workers that may come into contact with soil contamination in the future.

• Soil contamination represents a continuing liability to Defence.

CONTENTS • PRINT


5.2 caSE Study 2 –oPtionS to rEmEdiatE Pah contamination at a rESidEntial dEvEloPmEnt

Defence is responsible for cleaning up contamination at a

site that was formerly used as an airfield and is now subject to

redevelopment for residential use. Environmental investigations

have identified the presence of elevated concentrations of polycyclic

aromatic hydrocarbons (PAHs) in soils in areas that were formerly

host to sealed runways. The PAH contamination is thought to have

arisen from coal tar derived asphalt used to construct the runways.

The majority of the contamination, which is generally located within

the top 0.5m of the soil profile, is of a particulate nature and is easily

identifiable by its dark coloration against the lighter sandy soils.

Based on the conceptual site contamination model developed

by the environmental consultant, a number of remediation options

have been established in consultation with the site developer,

local Council, and EPA. These are:

OPTION 1 Capping of the contamination in-situ by the use of

a double barrier capping system comprising a layer of clay and

a synthetic membrane;

OPTION 2 Excavation and transfer of soil to a nearby site owned

by the local Council that is used for industrial/ commercial purposes;

OPTION 3 Excavation and disposal of the contaminated soil

to landfill located approximately 50 km from the site;

OPTION 4 Reduction of the contaminated mass by dry soil

screening to separate the coal tar asphalt particulates, followed

by off-site disposal of the coal tar asphalt to landfill and reuse

of the clean soil on-site; and

OPTION 5 Reduction of the contaminated mass by dry soil

screening to separate the coal tar asphalt particulates, followed by

thermal treatment of the coal tar asphalt and re-use of the remaining

soil on-site.

The potential environmental, social and financial sustainability considerations for each of these options are outlined in Table 5.

Table 5 – Case Study 2 – PAH Contamination at a Residential Development


OPTION 1

In-situ encapsulation using a double layered capping system

(Pathway control)

Positive

• Lower energy option results in lower generation of greenhouse gasses.

• Less likely to impact other parts of the environment by shifting contamination.

• Reduction in risk to workers during construction as soil contamination remains undisturbed.

• Initial capital costs are low compared to other options.

• There are likely to be significant upfront cost savings compared with excavation, transport and disposal or treatment.

Negative

• Higher level of uncertainty that groundwater or storm-water will not be impacted from leaching of PAHs from soils.

• Increase in risk to workers that may come into contact with soil contamination during maintenance and/or installation of underground services in the future.

• Higher level of uncertainty regarding the adequateness of the barrier.

• The burden of ongoing maintenance and responsibility for the contamination into the future.

• Community acceptance may be difficult to achieve due to negative public perception.

• Contamination financial liability remains with the site.

• On-going costs associated with maintenance and management.

Case Studies

CONTENTS • PRINT



OPTION 2

Excavation and placement of contaminated soil to a nearby commercial/ industrial site

(Receptor control)

Positive

• Higher level of certainty that the contamination will not pose a threat to the environment on the residential site.


• Reduced OH&S risks associated with transport of contaminated soils due to shorter transport distance compared to landfill option.

• Reduced OH&S risks associated with transport of contaminated soils due to shorter transport distance compared to landfill option.

• There are likely to be significant upfront cost savings compared with transport and disposal to landfill.

• Savings associated with reduction in need for importation of fill on industrial site by re-use of contaminated soil.

Negative

• Higher level of uncertainty that groundwater or storm-water will not be impacted from leaching of PAHs from soils on the industrial / commercial site.

• Energy and CO2 emissions required to excavate and transfer contaminated soil.

• Higher level of risk to workers (e.g. direct contact) and site users (e.g. dust inhalation) during the remediation works as a result of disturbance of the contaminated soils.

• Increase in risk to workers that may come into contact with soil contamination on the industrial commercial site.

• The burden of ongoing maintenance and responsibility for contamination management.

• Transfer of financial contamination liability from the residential to the industrial site.

• Potential on-going costs associated with maintenance and management of the contamination on the industrial site.

OPTION 3

Excavation of the contaminated soil and off-site disposal to landfill

(Source removal)

Positive

• Higher level of certainty that the contamination will not pose a threat to the environment on-site.




• Contamination financial liability is removed.

Negative

• Energy and CO2 emissions required to excavate and transfer contaminated soil to landfill.

• Contamination risk is transferred to the receiving facility.

• Higher level of risk to workers and site users during the excavation works as a result of disturbance of the contaminated soils.

• High costs associated with excavation, transport and off-site disposal of bulk quantities of soil.

• Contamination is transferred to the off-site receiving facility by liability may (strictly speaking) remain with the polluter.

OPTION 4

On-site separation followed by off-site disposal of coal tar asphalt and on-site reuse of clean soil

(Source removal)

Positive

• Volume of contamination is reduced.

• Reuse of separated clean soil will reduce the need to import additional material.




• Potential for cost savings by reduction in the need to import additional fill.

Negative

• Energy and CO2 emissions required to excavate, sort and transport contaminated soil.

• Higher level of risk to workers (e.g. direct contact) and site users (e.g. dust inhalation) as a result of disturbance of the contaminated soils during the excavation and sorting process.

• Potential high costs associated with disposal of more highly concentrated coal-tar material.

• Costs for machinery required for separation process.

OPTION 5

On-site separation followed by on-site thermal treatment of coal tar asphalt and on-site reuse of clean soil

(Source removal)

Positive

• Contamination is destroyed.

• Reuse of separated clean soil will reduce the need to import additional material.




• Savings made by avoidance of off-site disposal and transport costs.

Negative

• High energy and CO2 emissions required to thermally treat coal tar, in addition to energy usage for excavation and sorting.

• Heavy metals in the thermal treatment feed may produce a treated solid residue that requires stabilisation.

• Higher level of risk to workers and site users during the remediation works as a result of dust and odors generated during the thermal treatment process.

• Potential for off-site impacts associated with dust and noise from thermal treatment.

• Relatively high cost of establishment and operation of on-site thermal treatment facility.

• Costs for machinery required as part of separation process.

Case Studies

CONTENTS • PRINT


5.3 caSE Study 3 – lnaPl imPactS at a FuEl Farm

Through routine groundwater monitoring Defence has identified

the presence of light non-aqueous phase liquid (LNAPL) on

the water table below a fuel farm located at a remote Army

training facility. The LNAPL is thought to have arisen from a

leaking underground diesel storage tank which has since been

decommissioned and removed. The LNAPL represents a secondary

source of contamination. In addition to the LNAPL, there are

also low concentrations of dissolved phase contamination in

the groundwater including naphthalene.

Following the discovery, further phases of investigation have

demonstrated that the LNAPL and dissolved phase plume is

currently stable, and that the closest sensitive receptor (a river

located approximately 500 m from the site) is unlikely to be impacted

by the plume due to the natural attenuation capacity of the aquifer.

There are no buildings or other infrastructure located in the vicinity of

the fuel farm.

A detailed source-pathway-receptor analysis, including contaminant

transport modeling and a risk assessment using the Defence CRAT,

has been presented at a remediation workshop with base personnel

and other relevant stakeholders. The following contamination

management response actions have been found to be generally

acceptable to all stakeholders:

OPTION 1 Aggressive total fluids pumping to attempt to remove

the dissolved phase and LNAPL plume over a 1-year period – full

source removal;

OPTION 2 Installation of active skimming pumps to remove LNAPL

over a period of 3 to 4 years.– partial source removal; or

OPTION 2 Monitored natural attenuation – pathway control.

The potential environmental, social and financial sustainability

considerations for each of these options are outlined in Table 6.

Table 6 – Case Study 3 – LNAPL Contamination at a Fuel Farm – Sustainability Considerations


OPTION 1

Aggressive total fluids pumping to attempt to remove dissolved phase and LNAPL plume over a 1-year period

(Source removal - full)

Positive

• Greater potential for total removal of the contamination leading to greater certainty that the contamination will not pose a concern to the environment in the future.

• Removal of burden to continue monitoring of the contamination into the future.

• Active groundwater remediation has greater potential to achieve community and regulator objectives.

• Reduced requirement for costly ongoing groundwater monitoring.

Negative

• High energy use and CO2 emissions required for pumping, transport and treatment of contaminated water and LNAPL.

• Energy wastage associated with pumping, transport and disposal of excess (uncontaminated) groundwater.

• Potential for smearing of, or trapping LNAPL in the saturated zone, as a result of water table depression.

• Higher level of risk to workers undertaking the remediation works who may come into contact with the contamination.

• Safety hazards associated with road transport of contaminated water and LNAPL.

• High cost associated with pumping, storage, transport and disposal of LNAPL and contaminated groundwater.

OPTION 2

Installation of active LNAPL skimming pumps to remove LNAPL over a period of 3-4 years

(Source removal - partial)

Positive

• Lower potential of ongoing dissolved phase contamination by removal of the secondary source.

• Reduced burden to continue monitoring of the contamination into the future.

• Active groundwater remediation has greater potential to achieve community and regulator objectives.

• Reduced requirement for costly ongoing LNAPL monitoring in the future.

Negative

• Reduced certainty that dissolved phase contamination will not pose an environmental risk in the future.

• Energy use and CO2 emissions required for pumping, transport and treatment of LNAPL.

• Environment risks associated with transport and disposal of LNAPL.

• Higher level of risk to workers undertaking the remediation works who may come into contact with the LNAPL.

• Cost associated with set-up and ongoing maintenance of active skimming system over a 3 to 4 year period and disposal of LNAPL.

Case Studies

CONTENTS • PRINT


OPTION 3

Monitored natural attenuation

(Pathway control)

Positive

• Averts the need for high energy use and CO2 emissions required for pumping, transport and treatment of contaminated water and LNAPL.

• Lower level of risk to workers undertaking the remediation works who may come into contact with contaminated media.

• Averting the need to install pumping systems and transport and dispose of contaminated water and LNAPL may represent a significant cost saving.

Negative

• Higher risk that receptor will be impacted.

• Greater potential for plume to expand.

• Energy and resource usage associated with frequent and ongoing sampling and analysis and need for additional monitoring wells

• Burden to continue monitoring of the contamination into the future.

• Future cost to manage or remediate may be high if natural attenuation is unsuccessful in management of the plume.

• High cost of ongoing monitoring of the plume into the future

Case Studies

CONTENTS • PRINT

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Appendix ARemediation Technology Sustainability Considerations

Technology Applicability Examples of Sustainability Considerations Applicable to Specific Remediation Technologies


SOIL REMEDIATION

IN-SITU SOIL TREATMENT

Bioventing

Stimulates the natural in situ biodegradation of aerobically degradable compounds in soil by providing oxygen to existing soil microorganisms. In contrast to soil vapor vacuum extraction, bioventing uses low air flow rates to provide only enough oxygen to sustain microbial activity.

Petroleum hydrocarbons, non-chlorinated solvents, some pesticides, wood preservatives, and other organic chemicals

• Generation of off-gases may adversely impact air quality and increase greenhouse emissions.

• Average time: ~1 – 3 years.

• Degree of operation and maintenance required = Low.

• Allows soil to be treated without being excavated and transported, causing less disturbance to site activities.

• Potential for accumulation of vapors in building basements within the radius of influence of air injection wells.

• Relative cost: Low.

• Soil types containing sand and gravel produce significantly lower costs by reducing the number of injection/extraction wells required.

• Surface area is the primary cost driver as it impacts the number of injection/extraction wells required.

• May be cost effective compared to methods involving excavation and transportation.

Enhanced Bioremediation

The activity of naturally occurring microbes is stimulated by circulating water-based solutions through contaminated soils to enhance in situ biological degradation of organic contaminants or immobilisation of inorganic contaminants. Nutrients, oxygen, or other additives may be used to enhance bioremediation and contaminant desorption from subsurface materials.

Sludges, and groundwater contaminated with petroleum hydrocarbons, solvents, pesticides, wood preservatives, and other organic chemicals.

• The circulation of water through the soil may increase contaminant mobility resulting in contamination of the underlying groundwater.

• Cleanup goals may not be attained if the soil matrix prohibits contaminant-microorganism contact.

• High concentrations of heavy metals, highly chlorinated organics, long chain hydrocarbons, or inorganic salts are likely to be toxic to microorganisms.

• Both contaminated groundwater and soil can be treated simultaneously.


• Degree of operation and maintenance required = High.

• Allows soil to be treated without being excavated and transported, causing less disturbance to site activities.

• Remediation times are dependent on the degradation rates of specific contaminants, site characteristics, and climate.

• Regulators may not accept the addition of nitrates or non-native microorganisms to contaminated soils.


• Factors that affect cost include the soil type and chemistry, type and quantity of additives used, and type and extent of contamination.

• Can save significant costs over methods involving excavation and transport.

• Preferential colonisation by microbes may occur causing clogging of nutrient and water injection wells leading to requirement for replacement.

• A surface treatment system, such as air stripping or carbon adsorption, may be required to treat extracted groundwater prior to re-injection or disposal.

Phyto-remediation

Uses plants to remove, transfer, stabilise, and destroy organic or inorganic contaminants in soil and sediment.

Applicable for the remediation of metals, pesticides, solvents, explosives, crude oil, PAHs, and landfill leachates.

• High concentrations of hazardous materials can be toxic to plants.

• The toxicity and bioavailability of biodegradation products is not always known.

• Products may be mobilised into groundwater or bio-accumulate in animals.

• Average time: ~ Greater than 3 years.


• Stakeholder buy-in may be difficult as technology is still in the demonstration stage remains unfamiliar to regulators.


• The area of contamination requiring treatment is the primary cost driver.

• Sampling costs may be high - may be directed by regulatory requirements.

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Chemical Oxidation

Chemically converts hazardous contaminants to non-hazardous or less toxic compounds that are more stable, less mobile, and/or inert. The oxidising agents most commonly used are ozone, hydrogen peroxide, hypochlorites, chlorine, and chlorine dioxide.

Capable of achieving high treatment efficiencies for unsaturated aliphatic (e.g., TCE) and aromatic compounds (e.g., benzene).

• Careful consideration must be given to the effects of oxidation on the system. Can decrease the pH if the system is not buffered effectively. Other potential effects include: colloid genesis leading to reduced permeability; mobilisation of redox-sensitive and exchangeable sorbed metals; possible formation of toxic byproducts; evolution of heat and gas; and biological perturbation.

• Average time: ~ Less than 1 year.


• Risks to workers associated with handling large quantities of hazardous oxidizing chemicals.

• Relative cost: Medium.

• Rapid and extensive reactions with various COCs applicable to many bio-recalcitrant organics and subsurface environments can reduce costs by addressing a number of contaminants using the same technique.

• Can be tailored to a site and implemented with relatively simple, readily available equipment reducing costs associated with specialist contractors.

Soil Vapour Extraction

In situ unsaturated (vadose) zone soil remediation technology in which a vacuum is applied to the soil to induce the controlled flow of air and remove volatile and some semivolatile contaminants from the soil. The gas leaving the soil may be treated to recover or destroy the contaminants.

Suitable for volatile organic compounds and some fuels.

• Residual liquids may require treatment/disposal as a result of off-gas treatment.

• Spent activated carbon will require regeneration or disposal.

• Average time: ~ 1 – 3 years.


• Exhaust air from in situ SVE system may require management to prevent impact to surrounding land users.


• Soil that has a high percentage of fines and a high degree of saturation will require higher vacuums (increasing costs) and/or hindering the operation of the in situ SVE system.

• Pulsed operation can increase the cost-effectiveness of the system by facilitating extraction of higher concentrations of contaminants.

• Quantity of material treated has a large impact on costs as does the number of wells required and the requirement for airflow treatment.

Solidification/ Stabilisation

Contaminants are physically bound or enclosed within a stabilised mass (solidification), or chemical reactions are induced between the stabilising agent and contaminants to reduce their mobility (stabilisation).

Target contaminant group is generally inorganics (including radionuclides).

• Future use of the site may “weather” the materials and affect ability to maintain immobilisation of contaminants.

• Processing of contamination below the water table may require dewatering.

• Heavy machinery with high energy demands required for in-situ mixing process.


• Degree of operation and maintenance required = Average.

• Reagent delivery and effective mixing are more difficult than for ex situ applications.

• The effects, over the long term, of weathering, ground water infiltration, and physical disturbance associated with uncontrolled future land use can affect the integrity of the stabilised mass and hinder future site use.


• Some processes result in a significant increase in volume, increasing costs of soil management.

• Processes vary widely according to materials or reagents used, their availability, project size, and chemical nature of contaminants

• Transportation costs for treatment chemicals (which are typically in large volumes) can make projects uneconomical.

Thermal – in-situ

Steam/hot air injection or electrical resistance/electromagnetic/fiber optic/radio frequency heating is used to increase the volatilisation rate of semi-volatiles and facilitate extraction.

The system is designed to treat SVOCs but will consequently treat VOCs.

Thermally enhanced SVE technologies also are effective in treating some pesticides and fuels, depending on the temperatures achieved by the system.

• High energy input.

• Residual liquids and spent activated carbon may require further treatment.



• Air emissions must be regulated to eliminate possible harm to the public and the environment.


• Air treatment and permitting will increase project costs.

• The primary cost driver is soil type - soil permeability. Soils of lower permeability (silts/silty-clays) are less expensive to remediate as they require less gas flow.

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EX-SITU SOIL TREATMENT

Dig and Dump

Excavation and transport of contamination off-site to a landfill or treatment facility.

Applicable to the complete range of contaminant groups with no particular target group.

• Disposal options for certain waste may be limited.

• Contaminants can potentially migrate from landfill from several pathways, including effluent discharge to surface water, rainfall surface runoff, leachate into ground water, volatilization to the atmosphere.

• Landfills can develop odour problems without proper design and maintenance.

• Average time: ~ Generally less than 1 year.

• Generation of fugitive emissions from landfill or treatment process may impact on surrounding land users.

• Transportation of the soil through populated areas may affect community acceptability.

• Excavation may be required as part of the development anyway – e.g. installation of a basement.

• Cost is highly variable, but increasing at a greater rate relative to other technologies.

• Depth and composition of the media requiring excavation must be considered.

Biopiling

Excavated soils are mixed with soil additives and placed in aboveground enclosures formed into piles and aerated with blowers or vacuum pumps. The treatment area will generally be covered or contained with an impermeable liner to minimise the risk of contaminants leaching into uncontaminated soil.

Treatment of non-halogenated VOCs and fuel hydrocarbons. Halogenated VOCs and SVOCs.

Pesticides can also be treated, but the process effectiveness will vary.

• Potential for generation of toxic degradation by-products.

• Potential for impacts to surface water or groundwater if structure is inadequately contained.



• Potential for odour issues to impact adjacent land users during excavation and construction of cell.


• Excavation of contaminated soils is required.

• Costs are dependent on the contaminant, procedure to be used, need for additional pre- and post-treatment, and need for air emission control equipment.

• Biopiles are relatively simple and require few personnel for operation and maintenance

Landfarming

Contaminated soil, sediment, or sludge is excavated, applied into lined beds, and periodically turned over or tilled to aerate the waste.

Contaminants successfully treated using land-farming include diesel fuel, No. 2 and No. 6 fuel oils, JP-5, oily sludge, wood-preserving wastes (PCP and creosote), coke wastes, and certain pesticides.

• Landfarming can transform contaminants into nonhazardous substances.

• Volatile contaminants present, such as solvents, may volatilise to the atmosphere causing air pollution.

• Potential for impacts to surface water or groundwater if structure is inadequately contained.

• Energy usage associated with the use of machinery for tilling.

• Average time: 1 – 3 years.


• May involve long time periods - the higher the molecular weight (and the more rings with a PAH), the slower the degradation rate.

• A large amount of space is required.

• Dust control is an important consideration, particularly during tilling and other material handling operations.


• Runoff collection facilities must be constructed and monitored.

• Costs associated with regular tilling which normally will involve the use of earth moving machinery.

Soil Washing

Contaminants sorbed onto fine soil particles are separated from bulk soil in an aqueous-based system on the basis of particle size. The wash water may be augmented with a basic leaching agent, surfactant, pH adjustment, or chelating agent to help remove organics and heavy metals.

Greatest application is to soils contaminated with a wide variety of heavy metal, radionuclides, SVOCs and fuels.

• Results in concentration of contaminants into a smaller volume that can be further treated or disposed of.

• Soil washing is a media transfer technology – fluids generated will require further treatment or disposal.

• Average time: Less than 1 year.


• Additional treatment steps may be required to address hazardous levels of washing solvent remaining in the treated residuals.

• Relative cost: High.

• May be cost effective compared to stabilisation or off-site disposal.

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Solidification Stabilisation

Contaminants are physically bound or enclosed within a stabilised mass (solidification), or chemical reactions are induced between the stabilising agent and contaminants to reduce mobility (stabilisation). Includes: bituminisation, emulsified asphalt, modified sulfur cement, polyethylene extrusion, pozzolan/Portland cement, radioactive waste solidification, sludge stabilisation, soluble phosphates, and vitrification/molten glass.

Target contaminant group is generally inorganics (including radionuclides) – systems designed to be more effective in treating organics are being developed and tested

• Organics are generally not immobilised.

• Heavy machinery with high energy demands required for mixing.



• Long-term effectiveness has not been demonstrated for many contaminant/process combinations.

• The solidified material may hinder future site use.

• The effects, over the long term, of weathering, ground water infiltration, and physical disturbance associated with uncontrolled future land use can affect the integrity of the stabilised mass and contaminant mobility.


• Some processes result in a significant increase in volume (up to double the original volume) increasing costs of soil management.

• Processes vary widely according to materials or reagents used, their availability, project size, and chemical nature of contaminants.

• Transportation costs for treatment chemicals (which are typically in large volumes) can make projects uneconomical.

Incineration

High temperatures (870 – 1,200 °C) are used to combust (in the presence of oxygen) organic constituents in hazardous wastes.

Soils contaminated with explosives and hazardous wastes, particularly chlorinated hydrocarbons, PCBs, and dioxins.

• High energy usage and CO2 emissions.

• Heavy metals can produce a bottom ash that requires stabilisation.

• Heavy metals leave the combustion unit with the flue gases and require the installation of gas cleaning systems for removal.



• Potential risk of transporting the hazardous waste through the community if an off-site incinerator is used.

• Metals can react with other elements in the feed stream, forming more volatile and toxic compounds.


• Specific feed size and materials handling requirements that can impact applicability or cost at specific sites.

• High cost of establishment if on-site incineration is used.

Thermal Desorption

Wastes are heated to volatilise water and organic contaminants. A carrier gas or vacuum system transports volatilised water and organics to the gas treatment system. Thermal desorption is a physical separation process and is not designed to destroy organics.

Low Temperature Thermal Desorption (LTTD) effective for non-halogenated VOCs and fuels.

High Temperature Thermal Desorption (HTTD) effective for SVOCs, PAHs, PCBs, and pesticides

• Dewatering of soil may be required to achieve acceptable soil moisture content levels.

• Heavy metals in the feed may produce a treated solid residue that requires stabilisation.



• Processing system may generate dust or odour that will require control.


• Materials handling requirements can impact applicability or cost at specific sites.

• Clay and silty soils and high humic content soils increase reaction time resulting in increased costs.

• Thermal desorption systems are readily available off the shelf.

• Increased moisture requires higher heat input.

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Technology Applicability Examples of Sustainability Considerations Applicable to Specific Remediation Technologies


GROUNDWATER REMEDIATION

IN-SITU GROUNDWATER TREATMENT

Enhanced Biodegradation

The rate of bioremediation of organic contaminants by microbes is enhanced by increasing the concentration of electron acceptors and nutrients in ground water, surface water, and leachate. Oxygen is the main electron acceptor for aerobic bioremediation. Nitrate serves as an alternative electron acceptor under anoxic conditions.

Nonhalogenated VOCs & SVOCs and fuels. Nitrate enhancement has primarily been used to remediate groundwater contaminated by BTEX.

• Concentrations of hydrogen peroxide greater than 100 to 200 ppm in groundwater are inhibiting to microorganisms


• Safety risks associated with handling hydrogen peroxide.

• Nitrate injection into ground water may have adverse impact on its suitability for drinking water.


• Variables affecting the cost are the nature and depth of the contaminants, use of bio-augmentation and/or hydrogen peroxide or nitrate addition, and ground water pumping rates.

• The requirement for a surface treatment system, such as air stripping or carbon adsorption, to treat extracted ground water prior to re-injection or disposal may increase costs.

• For hydrogen peroxide enhanced treatment, costs are an order of magnitude more expensive than other methods of oxygen enhancement.

Natural Attenuation

Natural subsurface processes—such as dilution, volatilisation, biodegradation, adsorption, and chemical reactions with subsurface materials—are allowed to reduce contaminant concentrations to acceptable levels.

VOCs and SVOCs and fuel hydrocarbons.

Pesticides may also naturally attenuate, but the process may be less effective.

May also be appropriate for some metals when natural attenuation processes result in stabilisation by change in the valence state.

• Less generation or transfer of remediation wastes.

• Intermediate degradation products may be more mobile and more toxic than the original contaminant.

• Contaminants may migrate before they are degraded.

• The hydrologic and geochemical conditions amenable to natural attenuation may change over time resulting in renewed mobility of previously stabilised contaminants.


• Less intrusive as few surface structures are required.

• Longer time frames may be required to achieve remediation objectives, compared to active remediation, and the site may not be available for reuse until contaminant levels are reduced.

• Public acceptance of natural attenuation may be difficult to achieve.


• Overall cost likely to be lower than active remediation.

• Costs for monitoring including site characterisation and performance monitoring may be high.

• Costs for groundwater modelling can be high.

Air Sparging

Air is injected into saturated matrices to remove contaminants through volatilization. Injected air traverses horizontally and vertically through the soil column removing contaminants by volatilisation.

Target contaminant groups are VOCs and fuels.

• Potential for vapours to escape to the atmosphere.

• Soil heterogeneity may cause some zones to be relatively unaffected.



• Air flow through the saturated zone may not be uniform, which implies that there can be uncontrolled movement of potentially dangerous vapors.


• Surface area of contamination is the primary cost driver, and directly affects the quantity of air sparge points.

• Depth is the secondary cost driver. Cost increases with depth since it impacts the drilling costs.

Bioslurping

Combines the remedial approaches of bio-venting and vacuum-enhanced free-product recovery. Bio-venting stimulates the aerobic bioremediation of hydrocarbon-contaminated soils, while vacuum-enhanced free-product recovery extracts LNAPLs from the capillary fringe and the water table.

Used to remediate soils contaminated by petroleum hydrocarbons.

• Generation of off-gas from the bioslurper system requires treatment before discharge.

• Bioslurper systems can extract large volumes of water that may need to be treated prior to discharge depending on the concentration of contaminants in the process water.



• Low temperatures slow remediation.


• May be cost-effective by simultaneously removing LNAPL and achieving soil remediation in the vadose zone

• Costs associated with oil/water separators or treatment before process water can be discharged due to the mixing of the fuel, water and air phases that occurs during extraction.

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Chemical Oxidation

Chemically converts hazardous contaminants to less toxic compounds that are more stable, less mobile, and/or inert. Oxidising agents commonly used are ozone, hydrogen peroxide, hypochlorites, chlorine, and chlorine dioxide.

Capable of achieving high treatment efficiencies for unsaturated aliphatic (e.g., TCE) and aromatic compounds (e.g., benzene) with very fast reaction rates.

• Rapid and extensive reactions with various COCs applicable to many bio-recalcitrant organics and subsurface environments.

• Potential for process-induced detrimental effects.

• Average time: Greater than 10 years.


• Requirement for handling large quantities of hazardous oxidizing chemicals.

• Can be tailored to a site and implemented with relatively simple, readily available equipment.


• Cost drivers are quantity of material treated, moisture content in waste, high influent and low effluent concentrations.

• High costs of upfront investigations to determine reaction chemistry and transport processes.

Multi Phase Extraction

A high vacuum system is applied to simultaneously remove various combinations of contaminated groundwater, separate-phase petroleum product, and hydrocarbon vapor from the subsurface

VOCs and fuels including LNAPLs. • More effective than SVE for heterogeneous clays and fine sands, but not recommended for lower permeability formations due to the potential to leave isolated lenses of undissolved product in the formation.

• Will extract contaminated water with the product which may require separation prior to disposal or recycling.



• Use of dual phase extraction combined with bioremediation, air sparging, or bioventing can have a big impact on shortening cleanup times.


• Primary cost driver is soil type which determines permeability.

• As a result of the removal of substantial quantities of water during dual pumping operations, on-site water treatment will normally be required.

• Cost of additional treatment steps that may be necessary including treatment and disposal of process residuals.

Thermal Treatment

Steam is forced into an aquifer through injection wells to vaporise volatile and semivolatile contaminants. Vaporised components rise to the unsaturated zone where they are removed by vacuum extraction and then treated.

Most suitable for SVOCs and fuels. Sites include manufactured gas plants, wood-treating sites, petroleum-refining facilities, and other sites with soils containing light to dense organic liquids, such as coal tars, pentachlorophenol solutions, creosote, and petroleum by-products

• High energy input.

• Residual liquids and spent activated carbon may require further treatment.

• Average time: Less than 3 years.


• Air emissions may need to be regulated to eliminate possible harm to the public and the environment.


• The most significant factors affecting cost is the time of treatment or treatment rate, and the number of wells required per unit area which is related to the depth of contamination, permeability and site geology.

Permeable Reactive Barriers

A subsurface wall installed across the flow path of a contaminant plume which allows the water portion of the plume to passively move through, while prohibiting the movement of contaminants by employing agents such as zero-valent metals, chelators, sorbents, microbes, and others. The contaminants will either be degraded or retained in a concentrated form by the barrier material.

Target contaminant groups are VOCs, SVOCs, and inorganics. Can be used, but may be less effective, in treating some fuel hydrocarbons.

• Generation of by-products.

• Alteration of hydraulic characteristics of the aquifer.

• Average time: Greater than 10 Years.


• A passive treatment that requires long-term operation.

• Requirement for handling large quantities of hazardous oxidising chemicals.

• Critical that close attention be paid to worker training and safe handling of process chemicals.


• Key cost drivers include quantity of material treated and width of plume.

• Treatment agents can be expensive.

• Costs associated with installation of subsurface trench.

• Passive treatment walls may lose their reactive capacity, requiring replacement of the reactive medium.

Containment - Physical Barriers / Cut-off Walls

Installation of impermeable subsurface barriers consisting of vertically excavated trenches filled with an impermeable substance (e.g. Bentonite) to hydraulically contain or divert a groundwater contamination plume often used in conjunction with capping.

Applicable to a range of contaminant groups, and often are used where the waste mass is too large for treatment and where soluble and mobile constituents pose an imminent threat to a source of drinking water.

• Involve a large amount of heavy construction that may have other environmental impacts.

• Potential for the slurry walls to degrade or deteriorate over time resulting in migration of contaminants.

• Technology only contains contaminants within a specific area.

• Average time: Greater than 10 Years.


• Can provide an immediate solution to protection of drinking water supplies.

• Greater potential for site development to proceed unencumbered.

• Containment may not be an acceptable solution for regulators and the community.


• Equipment and methodology are readily available and well known.

• Often a cost effective alternative compared to active treatment methods.

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EX-SITU GROUNDWATER TREATMENT

Groundwater Pump & Treat/Dispose

Ground water pumping is a component of many pump-and-treat processes, which are some of the most commonly used groundwater remediation technologies at contaminated sites.

Applicable to a range of contaminant groups. • Drawdown pumping generally produces large volumes of water in the process of recovering the free product.

• The production of a cone of depression in the water table can smear the free product or trap the fuel in the saturated zone when the water table returns to its original level.



• Potentially long time necessary to achieve the remediation goal.

• Imposition on site activities of pumping, collection and treatment systems.

• Potential for odour and noise issues.


• The cost of permitting procuring and operating treatment systems is high.

• Additional cost may also be attributed to the disposal of spent carbon and other treatment residuals and wastes.

• Bio-fouling of the extraction wells and associated treatment stream can result in costly long term maintenance.

Constructed Wetlands

Uses natural geochemical and biological processes inherent in an artificial wetland ecosystem to accumulate and remove metals, explosives, and other contaminants from influent waters. The process can use a filtration or degradation process.

Most commonly used in wastewater treatment for controlling organic matter; nutrients (nitrogen and phosphorus) and suspended sediments. Also suitable for controlling trace metals, and other toxic materials. Can be used to treat acid mine drainage.

• The long-term effectiveness is not well known. Wetland aging may lead to a decrease in contaminant removal rates over time.

• Heavy flows can overload the removal mechanisms, while dry spells can damage plants and severely limit wetland function.

• Temperature and fluctuations in flow affect wetland function

• Promotion of biodiversity.


• May enhance the local environment by providing aesthetic benefits.


• The cost of building an artificial wetland varies considerably from project and may not be financially viable for many sites.

• The technology can be developed and implemented using traditional process engineering approaches.

Air Stripping

Volatile organics are partitioned from extracted ground water by increasing the surface area of the contaminated water exposed to air. Aeration methods include packed towers, diffused aeration, tray aeration, and spray aeration.

Used to separate VOCs from water. Compounds include BTEX, chloroethane, TCE, DCE, and PCE.

• Relatively high energy use and CO2

emissions.

• Off-gases require treatment.



• Process noise and air emissions may impact on site occupants and adjacent land.

• Duration of cleanup may be tens of years and depends on the capture of the entire plume from the ground water.

• Low-profile air stripper unit is available that packs a number of trays in a very small chamber to maximise air-water contact while minimising space required on site.


• Potential for inorganic or biological fouling of the equipment, requiring pre-treatment or periodic column cleaning.

• Process energy costs are high. Other cost drivers are influent flow rate, relative contaminant volatility, and off-gas treatment (when necessary).

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DPS OCT015/10

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