Sustainability Concern of Contaminated Site Remediation

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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 - PowerPoint PPT Presentation

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  • Sustainability Concern of Contaminated Site RemediationDr. Daniel TsangLecturerDepartment of Civil and Natural Resources Engineering University of Canterbury New Zealand

  • BackgroundSustainable developmentadvance 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 remediationenvironmental impacts of remediation are less than impacts of leaving contaminated land untreateddecision-making process intergenerational risk societal engagement and support

  • BackgroundTraditional excavation and landfill disposal (dig and dump)ease of usequick exitapplicable for complex contaminationlandfill 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?"(CL:AIRE, 2007)To what extent we walk our talk?

  • potential for long-term liability (exit point of the site)human health and local environmental impactflexibility for future land use value of land redevelopment for residential, commercial, industrial uselocal communitynoise, dust, off-site transportation, risk to public, etcglobal sustainability natural resources (materials and energy), non-recyclable waste, greenhouse gas, etcstakeholder acceptancereputation and track recordKey Concerns

  • Example issues to be addressedRemedial Options(Bardos et al., 2001)

  • semi-qualitative, semi-quantitative method integrated interpretation of inventory resultsindividual impacts (triple bottom line) environmental aspectssocial aspectseconomic aspectsa range of categories and sub-categoriesscorings (outranking) weightings (relative importance)Multi-criteria analysis

  • Scores for excavation and landfill disposalMulti-criteria analysis(Harbottle et al., 2007)

  • Risk & Technical SuitabilityRiskshuman healthimpact on ecosystemTechnical suitability (risk-based land management) reduce potential risk to an acceptable levelsite-specific risk-based treatment objectives (fit-for-purpose land use)

    Subjective perceptionlay publictechnical experts

  • Risk & Technical SuitabilitySubjective perception on riskspriority?owner/developer property/land valuehealth effectsregulators ecological or commercial value to be gained from remediation? contaminated sediments at ports, lakes, and rivers?contaminated unconfined aquifers?

  • Risk & Technical SuitabilitySubjective perception on technical suitabilityin-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 communitywider community with special interests

  • Cost/Benefitgeneric costs available; precise costs can be quoted and contractedmarket(?) value of remediation more uncertain (e.g., location, location, location)

    Fixed CostsVariable CostsPermitting, Safety, and RegulatorySite ExcavationSite CharacterizationEquipment Lease and DepreciationCharacterization StudiesLabour (1/2/3 shifts)Bench-Scale Treatability TestsPersonal Protective EquipmentVendor Selection/ContractingFuel/ElectricityProcess Design and OptimizationWaterSite Infrastructure Requirements and PreparationChemical agents (for chemical-enhanced soil washing)Transport of Equipment to the SiteSampling and Chemical AnalysisPlant ErectionProcess Water Treatment Decontamination and Decommissioning of EquipmentDisposal Cost of Contaminated Fines Fraction (optional in chemical-enhanced soil washing)Transport of Equipment from the SiteDisposal Cost of Treatment Process Wastes (e.g., sludge cake)

  • Excavation and Landfill Disposal Process Flow

    Soil Washing Process Flow

    Local & Global Sustainability(Diamond et al., 1999)(Harbottle et al., 2008)

  • 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

  • LimitationsComplex life cycle assessment of each processdata-intensivesite-specificdetailed impact assessmentdata not always available beforehandsemi-quantitative qualitative and subjectivea tool to facilitate the identification of key impacts, decision-making, and community engagementLocal & Global Sustainability

  • SummaryMCA compares overall performance of various technologiesvariability of technical operations, site-specific conditions, subjective perspectives on the relative importance (weighting) and technical performance (scoring) in various impactscomplex, data-intensive life cycle assessment may be impossible ahead of project implementationwith these limitations in mind, a prudent assessment of overall sustainability of remediation alternatives can facilitate the identification of key impacts, decision-making, and community engagementThanks for your time Questions are most welcome(daniel.tsang@canterbury.ac.nz)

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