Transcript Document
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?"
To what extent we ‘walk our talk’?
(CL:AIRE, 2007)
Key Concerns
potential for long-term liability (exit point of the site)
flexibility for future land use
noise, dust, off-site transportation, risk to public, etc
global sustainability
value of land redevelopment for residential, commercial, industrial use
local community
human health and local environmental impact
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
Risks
human health
impact on ecosystem
Source
Pathway
Receptor
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
Cost/Benefit
generic costs available; precise costs can be quoted and contracted
market(?) value of remediation more uncertain (e.g., location, location, location)
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)
Local & Global Sustainability
Excavation and Landfill Disposal Process Flow
(Harbottle et al., 2008)
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, decisionmaking, 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])