Sustainability Concern of Contaminated Site Remediation
Dr. Daniel TsangLecturer
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
ReceptorPathwaySource
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 Costs Variable Costs
Permitting, Safety, and Regulatory Site Excavation
Site Characterization Equipment Lease and Depreciation
Characterization Studies Labour (1/2/3 shifts)
Bench-Scale Treatability Tests Personal Protective Equipment
Vendor Selection/Contracting Fuel/Electricity
Process Design and Optimization Water
Site Infrastructure Requirements and Preparation Chemical agents (for chemical-enhanced soil washing)
Transport of Equipment to the Site Sampling and Chemical Analysis
Plant Erection Process 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([email protected])
