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Sustainability Concern of Contaminated Site Remediation. Dr. Daniel Tsang Lecturer Department of Civil and Natural Resources Engineering University of Canterbury New Zealand. Background. Sustainable development

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Sustainability concern of contaminated site remediation

Sustainability Concern of Contaminated Site Remediation

Dr. Daniel Tsang

Lecturer

Department of Civil and Natural Resources Engineering

University of Canterbury

New Zealand


Background
Background

  • Sustainable development

    • advance civilization without jeopardizing our future generations and natural diversity

    • utilize limited natural resources as efficiently as possible while preserving the environment with prudent care

    • meet human needs in the indefinite future

    • future benefits outweigh cost of remediation

    • environmental impacts of remediation are less than impacts of leaving contaminated land untreated

    • decision-making process

      • intergenerational risk

      • societal engagement and support


Background1
Background

  • Traditional – excavation and landfill disposal (‘dig and dump’)

    • ease of use

    • quick exit

    • applicable for complex contamination

    • landfill space? non-recyclable waste?

    • transportation? fuel? greenhouse gas?

    • backfill materials?

"Do you consider the sustainability of any aspects of a project in the selection of a remediation technology?"

To what extent we ‘walk our talk’?

(CL:AIRE, 2007)


Key Concerns

  • potential for long-term liability (exit point of the site)

    • human health and local environmental impact

  • flexibility for future land use

    • value of land redevelopment for residential, commercial, industrial use

  • local community

    • noise, dust, off-site transportation, risk to public, etc

  • global sustainability

    • natural resources (materials and energy), non-recyclable waste, greenhouse gas, etc

  • stakeholder acceptance

  • reputation and track record


Remedial Options

Example issues to be addressed

(Bardos et al., 2001)


Multi-criteria analysis

  • semi-qualitative, semi-quantitative method

  • integrated interpretation of inventory results

  • individual impacts (triple bottom line)

    • environmental aspects

    • social aspects

    • economic aspects

  • a range of categories and sub-categories

  • scorings (outranking)

  • weightings (relative importance)


Multi-criteria analysis

Scores for excavation and landfill disposal

(Harbottle et al., 2007)


Risk technical suitability
Risk & Technical Suitability

  • Risks

    • human health

    • impact on ecosystem

  • Technical suitability (risk-based land management)

    • reduce potential risk to an acceptable level

    • site-specific risk-based treatment objectives (fit-for-purpose land use)

  • Subjective perception

    • lay public

    • technical experts


Risk technical suitability1
Risk & Technical Suitability

  • Subjective perception on risks

    • priority?

    • owner/developer

      • property/land value

      • health effects

    • regulators

      • ecological or commercial value to be gained from remediation?

      • contaminated sediments at ports, lakes, and rivers?

      • contaminated unconfined aquifers?


Risk technical suitability2
Risk & Technical Suitability

  • Subjective perception on technical suitability

    • in-situ options

      • long-term liability (e.g., in-situ containment, S/S)?

      • spreading, residual, duration, effectiveness (e.g., PRBs, soil flushing, phytoremediation, bioremediation)?

    • ex-situ options

      • associated noise, dust?

      • air pollution?

      • risk to neighbours?

      • impact on soil/ecology?

    • preference of ex-situ or in-situ options?

    • stakeholders acceptance/confidence?

      • local community

      • wider community with special interests


Cost/Benefit

  • generic costs available; precise costs can be quoted and contracted

  • market(?) value of remediation more uncertain (e.g., location, location, location)


Local & Global Sustainability

(Harbottle et al., 2008)

  • Excavation and Landfill Disposal Process Flow

  • Soil Washing Process Flow

(Diamond et al., 1999)


Local & Global Sustainability

Containment Process Flow

(Diamond et al., 1999)


Local & Global Sustainability

Life cycle assessment of each process

(Blanc et al., 2004)


Local & Global Sustainability

Permeable reactive barriers

(Bayer and Finkel, 2006)


Local & Global Sustainability

  • Limitations

    • Complex life cycle assessment of each process

    • data-intensive

    • site-specific

    • detailed impact assessment

  • data not always available beforehand

  • semi-quantitative → qualitative and subjective

  • a tool to facilitate the identification of key impacts, decision-making, and community engagement


Summary

  • MCA compares overall performance of various technologies

  • variability of technical operations, site-specific conditions, subjective perspectives on the relative importance (weighting) and technical performance (scoring) in various impacts

  • complex, data-intensive life cycle assessment may be impossible ahead of project implementation

  • with these limitations in mind, a prudent assessment of overall sustainability of remediation alternatives can facilitate the identification of key impacts, decision-making, and community engagement

  • Thanks for your time – Questions are most welcome

  • ([email protected])


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