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  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

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?" (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 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 Key Concerns

Example issues to be addressed Remedial Options (Bardos et al., 2001)

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 Multi-criteria analysis (Harbottle et al., 2007)

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 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 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

Fixed CostsVariable Costs Permitting, Safety, and RegulatorySite Excavation Site CharacterizationEquipment Lease and Depreciation Characterization StudiesLabour (1/2/3 shifts) Bench-Scale Treatability TestsPersonal Protective Equipment Vendor Selection/ContractingFuel/Electricity Process Design and OptimizationWater Site Infrastructure Requirements and PreparationChemical agents (for chemical-enhanced soil washing) Transport of Equipment to the SiteSampling and Chemical Analysis Plant ErectionProcess Water Treatment Decontamination and Decommissioning of Equipment Disposal Cost of Contaminated Fines Fraction (optional in chemical-enhanced soil washing) Transport of Equipment from the Site Disposal Cost of Treatment Process Wastes (e.g., sludge cake) Cost/Benefit generic costs available; precise costs can be quoted and contracted market(?) value of remediation more uncertain (e.g., location, location, location)

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

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 Local & Global Sustainability

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