Sustainability Concern of Contaminated Site Remediation

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

2. 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

3. 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)

4. 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

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

6. 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)

7. Multi-criteria analysis Scores for excavation and landfill disposal (Harbottle et al., 2007)

8. 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

9. 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?

10. 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

11. Cost/Benefit • generic costs available; precise costs can be quoted and contracted • market(?) value of remediation more uncertain (e.g., location, location, location)

12. Local & Global Sustainability (Harbottle et al., 2008) • Excavation and Landfill Disposal Process Flow • Soil Washing Process Flow (Diamond et al., 1999)

13. Local & Global Sustainability Containment Process Flow (Diamond et al., 1999)

14. Local & Global Sustainability Life cycle assessment of each process (Blanc et al., 2004)

15. Local & Global Sustainability Permeable reactive barriers (Bayer and Finkel, 2006)

16. 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

17. 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 • (daniel.tsang@canterbury.ac.nz)