Using Site-Specific Life Cycle Using Site-Specific Life Cycle Inventory to Support a Inventory to Support a

Contaminated Site Contaminated Site Management DecisionManagement Decision

J.F. MÉNARD, J. GODIN, S. HAINS, L. DESCHÊNES, R. SAMSON

Seattle, 23-09-03

Goal of the StudyGoal of the Study

• Identify, among four alternatives, the management option for a landfill site that minimizes potential environmental impacts, classified as:

– Primary impacts: generated by the landfill leachate, mainly contributing to local impacts (ETP and HTP);

– Secondary impacts: generated by the site management operations (i.e.: excavation, waste transportation,…).

Presentation OutlinePresentation Outline

Goal and Scope DefinitionGoal and Scope Definition- site history site history - management scenarios management scenarios - functional unitfunctional unit

Inventory analysis Inventory analysis - system definitionsystem definition- data source summarydata source summary- assumptionsassumptions

Results summaryResults summary- LCIALCIA- Sensitivity analysisSensitivity analysis

Conclusions and LimitsConclusions and Limits

Site HistorySite History

SPENT POTLINING (SPL) LANDFILL: - A waste produced from aluminum refining;- Classified as a dangerous waste in North America

in the late 1980’s;- Major contaminants: Fluoride, Cyanide, Fe, Al.

Site HistorySite History1980: Closure of the landfill: 360 000 m3 of waste mix and 100 000 m3 of SPL;

1989: Covered with a waterproof liner to limit landfill leachate generation;

Today, groundwater is still contaminated and so is the surface water at the site’s edge;

Contaminated soil (before capping) - slow release of adsorbed contaminants.

Management ScenariosManagement Scenarios

Energeticvalorization

No-intervention

Secure landfilling

On-site cellstorage

Treatment andlandfilling

3a

In-situ management (option 1)

SPL

Other wastes

Contaminatedsoil

32

2

3b

2

3

Ex-situ management (options 2 and 3)

The site represents a low risk for the aquatic ecosystem (preliminary ERA);Contaminants such as cyanide have a potential for natural attenuation (Meehan et al., 1999).

Functional UnitFunctional UnitThe management, for a period of 50 years, of the landfill site (i.e.: 360 000 m3 of waste mix, 100 000 m3 of SPL and 200 000 m3 of contaminated soils).

0

100

200

300

400

500

600

700

800

1989 1994 1999 2004 2009 2014 2019 2024 2029 2034 2039 2044 2049

Time (years)

Flu

ori

de

co

nc

en

tra

tio

n (

mg

/L)

B.C. fluoride guideline = 1.5 mg/L

MW-12a50 years : Period of time estimated for pseudo-steady-state conditions to be reached under the no-intervention scenario.- Excludes: long term

emissions caused by the eventual deterioration of capping.

System Definition System Definition

Site preparation

Containment ofwaste mix in on-site

storage cells

Excavation of SPL,waste mix and

contaminated soilSite closure

on-site Trp(truck)

Contaminatedsoil monitoring

Long-termgroundwatermonitoring

OPTION 2

OPTION 1

Long-termgroundwatermonitoring

emissionsto air

emissionsto water

solidemissions

emissionsto soil

emissionsto air

emissionsto water

solidemissions

emissionsto soil

energy

rawmaterials

energy

rawmaterials

System DefinitionSystem Definition

Site preparation

Containment ofwaste mix in on-site

storage cells

Excavation of SPL,waste mix and

contaminated soilSite closure

energy

emissionsto air

emissionsto water

solidemissions

emissionsto soil

rawmaterials

Separation

Secure landfilling ofthe contaminated soil

fraction at CleanHarbor (Ontario)

3a:Treatment of the SPL fraction atWaste Management (Oregon)

3b:Incineration of the SPL fractionin Kamloops (BC)

off-siteTrp(train/ truck)

on-siteTrp(truck)

off-siteTrp(train)

Contaminatedsoil monitoring

Long-termgroundwatermonitoring

OPTIONS 3a/ 3b

Energetic valorization (3b): system expansion (ISO 14 049, 2000)

Data Source SummaryData Source SummaryProcesses Data sources

Water emissions related to SPL (landfill

leachate)Site specific modeling results

Non-road equipment (excavator, loader,…)

NONROAD model (U.S. EPA/Office of Transportation and Air Quality)

Transportation by truck

Joint EMEP/CORINAIR Emission Inventory Guidebook (UNECE/EMEP

Task Force, 2001)

Transportation by train Commercial databases - Franklin LCI US databaseMaterial production

Data Source SummaryData Source SummaryLandfill leachate flow simulations:

A predictive site-specific model was used to simulate the contaminants emissions to surface waters through groundwater:

Based on site-specific data: hydrogeological, geochemical, and microbiological characteristics.

Three-dimensional finite element model : FRAC3DVS model (Therrien and Sudicky, 1996).

AssumptionsAssumptions

Landfill leachate flow simulations: Geochemical conditions were assumed to be constant during the 50-year period.

Water emissions during excavation works (precipitation and infiltration ): Flow calculations are based on equipment

characteristics, economic and technical constraints: - Option 2 – over 4 years - Options 3a and 3b – over 7 years

The treatment was considered to be inefficient.

Volatile compounds released from SPL:Neglected.

LCIA MethodologyLCIA Methodology

Characterization factors have been developed:- ETP (Al, cyanide, fluoride) and HTP (Al)

Environmental impacts (EDIP Methodology) Indicator

Global warming potential (GWP) g CO2 eq.

Ozone depletion potential (ODP) g CFC11 eq.

Acidification potential (AP) g SO2 eq.

Nutrient enrichment potential (NP) g NO3 eq.

Photochemical ozone potential (POCP) g C2H4 eq.

Ecotoxicity – water, acute (ETWA)Ecotoxicity – water, chronic (ETWC)Ecotoxicity – soil, chronic (ETSC)

m3 water /gm3 water /gm3 soil /g

Human toxicity – air (HTA)Human toxicity – water (HTW)Human toxicity – soil (HTS)

m3 air /gm3 water /gm3 soil /g

Waste production g

Resource consumption g

0%

20%

40%

60%

80%

100%

GW

P

OD

P

AP

NP

PO

CP

ET

WC

ET

WA

ET

SC

HT

A

HT

W

HT

S W R

1 2 3a 3b

Summary of ResultsSummary of Results

Option 1 (No-intervention) has the lowest potential environmental impacts for all categories.

Option 3b is second except for GWP, AP, NP and POCP.

Comparative Assessment

Summary of ResultsSummary of Results

0%

20%

40%

60%

80%

100%

GW

P

OD

P

AP

NP

PO

CP

ET

WC

ET

WA

ET

SC

HT

A

HT

W

HT

S W R

Transport Primary

0%10%

20%30%

40%50%

60%70%

80%90%

100%

GW

P

OD

P

AP

NP

PO

CP

ET

WC

ET

WA

ET

SC

HT

A

HT

W

HT

S W R

1 2 3a 3b

Primary impacts

Option 1

Primary impacts are essentially local (on site).

Excavation reduces the primary impacts by a factor of 2.

-60%

-40%

-20%

0%

20%

40%

60%

80%

100%

GW

P

OD

P

AP

NP

PO

CP

ET

WC

ET

WA

ET

SC

HT

A

HT

W

HT

S W R

Excavation On-site cell Site closureSPL Incineration Soil landfilling Primary

On-site cell: material production contribution (ex.: steel = 10,7 ktons for Option 2).

Excavation water is the major contributor to ETWA and ETWC.

Summary of ResultsSummary of Results

0%

20%

40%

60%

80%

100%

GW

P

OD

P

AP

NP

PO

CP

ET

WC

ET

WA

ET

SC

HT

A

HT

W

HT

S W R

Excavation On-site cell Site closure Primary

0%

20%

40%

60%

80%

100%

GW

P

OD

P

AP

NP

PO

CP

ET

WC

ET

WA

ET

SC

HT

A

HT

W

HT

S W R

Excavation On-site cell Site closure

SPL Treatment Soil landfilling Primary

Option 2

Option 3a

Option 3a and 3b, important contribution of the long-distance transport by train (ex: soil to landfill - 4000 km)

Option 3b, beneficial effect of the reuse of the SPL fraction as an alternative fuel.

Option 3b

Sensitivity AnalysesSensitivity AnalysesTemporal boundary: leachate emissions over 100 years for Option 1: - Impacts increase < 7% for all concerned categories. Impacts increase < 7% for all concerned categories.

Amount of contaminated soil excavated:- Uncertain: between 140 000 mUncertain: between 140 000 m33 and 200 000 m and 200 000 m33;;- Baseline scenario: upper limit as worst case;Baseline scenario: upper limit as worst case;- Lower limit: reduces size of containment cell and Lower limit: reduces size of containment cell and

transported volume.transported volume.

Ranking remains the same.

ConclusionsConclusionsOption 1:

- Lowest potential environmental impacts;Lowest potential environmental impacts;

- Primary impacts (on-site) are significant (almost twice as much as for excavation scenarios);Primary impacts (on-site) are significant (almost twice as much as for excavation scenarios);

- Further investigations are required for the acceptance of Option 1 (i.e.: full ERA, evaluation of site-specific natural attenuation potential).Further investigations are required for the acceptance of Option 1 (i.e.: full ERA, evaluation of site-specific natural attenuation potential).

If Option 1 is rejected: Option 3b should be implemented based on the results of this comparative LCA:

- Further investigations to select an appropriate excavation water treatment to reduce the impact associated with the excavation life cycle stage.Further investigations to select an appropriate excavation water treatment to reduce the impact associated with the excavation life cycle stage.

Limits of the StudyLimits of the StudyPossible overestimation of the primary impacts: EDIP method considers no chemical degradation and all chemicals are biologically available;

Land-use impact category inclusion could appreciably influence results:- Option 1: the site is not restored.- Excavation options: the site is restored to the industrial criteria.

A longer temporal boundary could influence the results:- Option 1: deterioration of the capping resulting in increased leachate generation;

- Excavation options: secure cells were considered totally sealed but could themselves become sources of contamination in a long term perspective.

Using Site-Specific Life Cycle Using Site-Specific Life Cycle Inventory to Support a Contaminated Inventory to Support a Contaminated

Site Management DecisionSite Management Decision

QUESTIONSQUESTIONS

Additional information: Julie.godin@polymtl.ca

Seattle, 23-09-03

Summary of LCI ResultsSummary of LCI ResultsOption

sMass (kg) Life cycle stage contribution Inputs (> 1%)

2 8.6E8

2.5 On-site containment of waste mix (81%) sand (42%)gravel (40%)concrete (16%)steel (1.8%)2.4 Site closure (19%)

3a 9.7E8

3a.5 On-site containment of waste mix (46%)gravel (27%), clay (27%), sand (24%), concrete (14%)

3a.7 Off-site landfilling of cont. soil (19%)

3a.6 Off-site treatment of SPL (18%)

3a.4 Site closure (17%)

3b 7.4E8

3b.5 On-site containment of waste mix (53%)sand (27%), gravel (36%), clay (22%), concrete (11%), steel (1.2%)

3b.7 Off-site landfilling of cont. soil (25%)

3b.4 Site closure (22%)

Materials involved in excavation and disposal site remediation scenarios

Data Source SummaryData Source SummaryLandfill leachate flow simulation:

Calibrations:

1) Groundwater flow: by trial-and error using water table elevations measured on-site;

2) Contaminant fate and transport: - using different parameters (hydraulic

conductivities, dispersivity coefficients, Kd, and source concentrations);

- matching of the simulated concentrations with the average observed on-site concentrations.