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Laboratory Tests and Field Investigations of DNAPL Source Zone Remediation Using Granular Iron Laboratory Tests and Laboratory Tests and Field Investigations of Field Investigations of DNAPL Source Zone Remediation DNAPL Source Zone Remediation Using Granular Iron Using Granular Iron Sharon L.S. Wadley and Robert W. Gillham Sharon L.S. Wadley and Robert W. Gillham Department of Earth Sciences Department of Earth Sciences University of Waterloo University of Waterloo Waterloo, Ontario, Canada Waterloo, Ontario, Canada RTDF Meeting October 15 RTDF Meeting October 15 - - 16, 2003 16, 2003

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Laboratory Tests and Field Investigations of

DNAPL Source Zone Remediation Using Granular Iron

Laboratory Tests and Laboratory Tests andField Investigations of Field Investigations of

DNAPL Source Zone Remediation DNAPL Source Zone Remediation Using Granular IronUsing Granular Iron

Sharon L.S. Wadley and Robert W. GillhamSharon L.S. Wadley and Robert W. Gillham

Department of Earth SciencesDepartment of Earth Sciences University of WaterlooUniversity of Waterloo

Waterloo, Ontario, CanadaWaterloo, Ontario, Canada

RTDF Meeting October 15RTDF Meeting October 15--16, 200316, 2003

DNAPL Remediation Using Isolation Technology and Granular Iron

DNAPL Remediation Using Isolation DNAPL Remediation Using IsolationTechnology and Granular IronTechnology and Granular Iron

•• SoilSoil--mixing augers used to mix mixing augers used to mix ironiron--bentonitebentonite slurries slurries inin situsitu

•• BentoniteBentonite –– Initially, a lubricant and Initially, a lubricant and viscosiferviscosifer to to

facilitate injectionfacilitate injection –– Subsequently, reduces hydraulic Subsequently, reduces hydraulic

conductivity of mixed zoneconductivity of mixed zone

•• Mixing homogenizes Mixing homogenizes contaminated contaminated

•• Contaminant diffuses to iron Contaminant diffuses to iron surface within mixed zone surface within mixed zone dechlorinationdechlorination takes placetakes place

regionregion

wherewhere

Research ObjectivesResearch ObjectivesResearch Objectives

•• To determine, through laboratory testing, To determine, through laboratory testing, whether mixing granular iron,whether mixing granular iron, bentonitebentonite and saturated materials contaminated with and saturated materials contaminated with freefree--phase chlorinatedphase chlorinated ethenesethenes would would prove an effective remediation methodprove an effective remediation method

•• To demonstrate the concept in a field To demonstrate the concept in a field setting, to evaluate the remediation setting, to evaluate the remediation potential and installation methodpotential and installation method

ExperimentsExperimentsExperiments

1. 1.

2. 2.

3. 3.

Preliminary Batch ExperimentPreliminary Batch Experiment

Field DemonstrationField Demonstration

Laboratory ExperimentLaboratory Experiment

Experimental Preparation Experimental Preparation Experimental Preparation

Hypovials contained: Hypovials contained: (Wt%)(Wt%)

Master Builders Iron (medMaster Builders Iron (med--fine): fine): BaroidBaroid BensealBenseal®® Bentonite: Bentonite: 3.5 3.5 Borden Sand:Borden Sand: 23.5 23.5 Distilled water:Distilled water: 49.3 49.3 mLmL (average)(average) FreeFree--phase TCE: phase TCE: 0.11 g 0.11 g

Periodically, hypovials were sacrificed to measure aqueous concentrations of TCE and potential

degradation products

Periodically, hypovials were sacrificed to measure Periodically, hypovials were sacrificed to measure aqueous concentrations of TCE and potential aqueous concentrations of TCE and potential

degradation productsdegradation products

(5%)g 1.3 (5%) g 1.3 (12%)g (12%) g (83%)g (83%) g

(2x solubility)(2x solubility)

0

500

1000

1500

2000

2500

0 50 100 150

0

500

1000

1500

2000

TCE and Chloride ConcentrationsTCE and Chloride ConcentrationsTCE and Chloride Concentrations

Elapsed Time (days)

TCE

Con

cent

ratio

n (m

g/l)

Chl

orid

e C

once

ntra

tion

(mg/

l)

SolubilitySolubility

tt½½ = 11.1 hrs= 11.1 hrs (normalized to (normalized to

1 m1 m22 Fe / ml solution)Fe / ml solution)

Max Max ClCl--

0.00

2.00

4.00

6.00

8.00

10.00

0 50 100 150 200

VC 11DCE tDCE cDCE

Organic Degradation Products Organic Degradation Products Organic Degradation Products

Elapsed Time (days)

Con

cent

ratio

n (m

g/l)

Total organic degradation products Total organic degradation products < 1% original TCE< 1% original TCE

Field Demonstration: ObjectivesField Demonstration: ObjectivesField Demonstration: Objectives

•• To determine whether mixing slurries of To determine whether mixing slurries of granular iron and bentonite into granular iron and bentonite into contaminated geological material promotes contaminated geological material promotes in situin situ removal of DNAPLremoval of DNAPL

•• To test the feasibility of producing uniform To test the feasibility of producing uniform iron/bentonite/soil/DNAPL mixtures iron/bentonite/soil/DNAPL mixtures

CFB Borden: GeologyCFB Borden: GeologyCFB Borden: Geology

Surface Aquifer (Beach sand)Surface Aquifer (Beach sand)

Upper Aquitard (Silty clay)Upper Aquitard (Silty clay) Stiff Blocky TextureStiff Blocky Texture Soft Plastic TextureSoft Plastic Texture

Lower Aquitard (Lower Aquitard (DiamictDiamict))

Lower Aquifer (Silty sand)Lower Aquifer (Silty sand)

9x9 m Cell9x9 m Cell

Forested SiteForested Site

(m(m bgsbgs)) 00

3 3 –– 44

7.57.5

11.511.5

Site HistorySite HistorySite History

•• 19911991 9x9m sheet9x9m sheet--piling cell constructed inpiling cell constructed in Borden aquifer and keyed intoBorden aquifer and keyed into aquitardaquitard -- 771 L PCE released to monitor migration771 L PCE released to monitor migration -- 39 days later 39 days later –– PCE was found inPCE was found in aquitardaquitard

•• 19911991--33 425 L DNAPL removed425 L DNAPL removed

•• 19981998 KMnOKMnO44 experimentexperiment

Estimated PCE remaining 1998:Estimated PCE remaining 1998: 350 L (200 L in aquifer and 150 in350 L (200 L in aquifer and 150 in aquitardaquitard))

9x9 m Cell9x9 m Cell

9x9 m Cell Borden, ON 9x9 m Cell9x9 m Cell

Borden, ONBorden, ON

81 cm81 cm

61 cm61 cm

Iron-Bentonite(IB) Slurry

IronIron--BentoniteBentonite (IB) Slurry(IB) Slurry

Iron-BentoniteMixing Process IronIron--BentoniteBentonite Mixing ProcessMixing Process

•• IB slurry delivered IB slurry delivered to subsurface to subsurface through drill rodsthrough drill rods

•• Mixing blades were Mixing blades were raised and lowered raised and lowered several times to several times to homogenize regionhomogenize region

•• Tapered blades Tapered blades prevented materials prevented materials from surfacingfrom surfacing

Location of Mixed ZonesLocation of Mixed ZonesLocation of Mixed Zones

MZ1 (5% IB)MZ1 (5% IB)

MZ2 (10% IB)MZ2 (10% IB)

MZ3 (5% Ben.)MZ3 (5% Ben.)

MZ4 (5% IB)MZ4 (5% IB)

(m(m bgsbgs)) 00

3 3 –– 44

7.57.5

11.511.5 Sand Microbeds

Fractures

9x9 m Cell9x9 m Cell

Surficial Aquifer

Aquitard

Lower Aquifer

Location of Mixed Zones: Plan ViewLocation of Mixed Zones: Plan ViewLocation of Mixed Zones: Plan View

9x9m Cell9x9m Cell D

oor

MZ1 (5% IB)MZ1 (5% IB)

MZ2 (10% IB)MZ2 (10% IB)

MZ3 (5% Ben.)MZ3 (5% Ben.)

Background and MZ4 Background and MZ4 in Aquitard (5% IB)in Aquitard (5% IB)

Background AquiferBackground Aquifer (B1, B2, B3)(B1, B2, B3)

DNAPL in AquitardDNAPL in Aquitard

Background AquitardBackground Aquitard

KMnOKMnO44 InjectionsInjections

N

B2B2 B1B1 B3B3

1991 PCE Release

Field Sampling & AnalysesField Sampling & AnalysesField Sampling & Analyses Coring at SiteCoring at Site •• Soil samples were Soil samples were

stored in methanol and stored in methanol and acetonitrileacetonitrile

Laboratory AnalysesLaboratory Analyses •• GC/ECD analyses for GC/ECD analyses for

PCE and TCEPCE and TCE

•• GC/PID analyses for GC/PID analyses for VC and DCE isomersVC and DCE isomers

•• Combination electrode Combination electrode for Clfor Cl-­ analysesanalyses

Iron Distribution in AquiferIron Distribution in AquiferIron Distribution in Aquifer

Mixing Zone 2Mixing Zone 2 (10% Iron(10% Iron--bentonite)bentonite)

⇒⇒ wellwell--mixed but not homogenizedmixed but not homogenized

6.5 ft6.5 ft 7.0 ft7.0 ft

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 1 10 100 1,000 10,000

B1

B2

B3

Aquifer PCE ConcentrationsAquifer PCE ConcentrationsAquifer PCE ConcentrationsD

epth

(m b

gs)

Dep

th (m

bgs

)

Concentration (Concentration (µµg PCE / g soil)g PCE / g soil)

(Background)(Background)(Background)

DNAPL

B1B1

B2B2 B3B3

B2 nearB2 near centrecentre of of 9x9m Cell9x9m Cell

B3 near sheetB3 near sheet--piling wallpiling wall

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 1 10 100 1,000 10,000

Day 0

Day 39

Day 101

Day 404

Mixing Zone #1 Mixing Zone #1 Mixing Zone #1 D

epth

(m b

gs)

Dep

th (m

bgs

)(5% Iron-bentonite)(5% Iron(5% Iron--bentonite)bentonite)

Mixing Lim

itsM

ixing Limits

DNAPL

Concentration (Concentration (µµg PCE / g soil)g PCE / g soil)

tt½½ = 368 hrs= 368 hrs (normalized to (normalized to

1 m1 m22 Fe / ml solutionFe / ml solution

PCE ConcentrationsPCE ConcentrationsPCE Concentrations

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 1 10 100 1,000

Day 0

Day 35

Day 97

Day 400

Mixing Zone #2 Mixing Zone #2 Mixing Zone #2 (10% Iron-bentonite)(10% Iron(10% Iron--bentonite)bentonite)

Dep

th (m

bgs

)D

epth

(m b

gs)

Mixing Lim

itsM

ixing Limits

DNAPL

Concentration (Concentration (µµg PCE / g soil)g PCE / g soil)

PCE ConcentrationsPCE ConcentrationsPCE Concentrations

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 1 10 100 1,000 10,000

Day 0

Day 35

Day 97

Day 400

Mixing Zone #3 Mixing Zone #3 Mixing Zone #3 (Control - 0% Iron, 5% Bentonite)(Control (Control -- 0% Iron, 5% Bentonite)0% Iron, 5% Bentonite) D

epth

(m b

gs)

Dep

th (m

bgs

)

Mixing Lim

itsM

ixing Limits

DNAPL

Concentration (Concentration (µµg PCE / g soil)g PCE / g soil)

PCE ConcentrationsPCE ConcentrationsPCE Concentrations

Degradation Products in the AquiferDegradation Products in the AquiferDegradation Products in the Aquifer TCE and DCE isomersTCE and DCE isomers •• Total DCE in ironTotal DCE in iron--mixed zones < 0.5 mixed zones < 0.5 µµgg VOC / g soilVOC / g soil •• TCE was detected in background and mixedTCE was detected in background and mixed--zoneszones

ChlorideChloride •• Uncontaminated aquifer measures 1Uncontaminated aquifer measures 1--3 mg/L3 mg/L •• Background cores in 9x9m Cell 100Background cores in 9x9m Cell 100--300 mg/L300 mg/L •• Amounts detected in ironAmounts detected in iron--mixed zones did not mixed zones did not

correspond to PCE degradationcorrespond to PCE degradation –– Possibly due to nearby KMnOPossibly due to nearby KMnO44 experimentexperiment

•• Therefore, could not confirm PCE degradationTherefore, could not confirm PCE degradation

Cell Experiment: ObjectivesCell Experiment: ObjectivesCell Experiment: Objectives

•• Examine DNAPL disappearance Examine DNAPL disappearance using a substantial amount of freeusing a substantial amount of free--phase PCE, and under conditions in phase PCE, and under conditions in which the degradation process which the degradation process could be examined more reliably could be examined more reliably than the field demonstrationthan the field demonstration

ConstructionConstructionConstruction GasGas--ventingventing

valvevalve

Composition:Composition: PVC pipe andPVC pipe and plate weldedplate welded

10 side ports10 side ports (1.5 cm diameter)(1.5 cm diameter)

28 c

m28

cm

30 cm ID30 cm ID

AssemblyAssemblyAssembly •• Borden sand, Borden sand, BaroidBaroid

BensealBenseal®® bentonite, and bentonite, and Master Builder mediumMaster Builder medium--fine granular ironfine granular iron

•• Distilled water mixed Distilled water mixed until saturateduntil saturated

•• FreeFree--phase PCE (dyed phase PCE (dyed red with Sudan IV)red with Sudan IV)

•• Cell was packed and Cell was packed and sealed as quickly as sealed as quickly as possiblepossible

Cell Contents (by volume)Cell Contents (by volume)Cell Contents (by volume)

0.400.407%7% (0.5 L)(0.5 L)101055858533

8%8% (0.5 L)(0.5 L)

6%6% (0.5 L)(0.5 L)

PCE PCE (%(% pore pore space)space)

0.350.355555909022

0.480.48005595951 1 (control)(control)

Porosity Porosity of of CellCellaa

Iron Iron (%)(%)

BentoniteBentonite (Volume % (Volume % when wet)when wet)

Borden Borden SandSand

(Volume %)(Volume %) CellCell

a) a) Estimated using amount of water used to saturate cellEstimated using amount of water used to saturate cell

Sampling ProcedureSampling ProcedureSampling Procedure

Cored from Cored from side:side:

Shallow, Central Shallow, Central and Deep portsand Deep ports

1 2

3

4

5

6 7

8

9

1030 cm30 cm 28 cm28 cm

Sampling ProcedureSampling ProcedureSampling Procedure

Cored from Cored from side:side:

Shallow, Central Shallow, Central and Deep portsand Deep ports

1 2

3

4

5 30 cm30 cm

4 samples taken from each port:4 samples taken from each port:

28 cm28 cm

Analyses:Analyses: PCE, TCE PCE, TCE

DCE isomersDCE isomers Vinyl ChlorideVinyl Chloride

ChlorideChloride 11stst & 3& 3rdrd stored in methanolstored in methanol

22ndnd & 4& 4thth stored in acetonitrilestored in acetonitrile

11 3322 44

0

5,000

10,000

15,000

20,000

25,000

0 200 400 600 800 1000 1200

Shallow Port (18 cm*) Central Port (11 cm*) Deep Port (3 cm*) Average

Cell 1 (Control) PCE Concentrations

Cell 1 (Control) Cell 1 (Control)PCE ConcentrationsPCE Concentrations

Elapsed Time (days)Elapsed Time (days)

Con

cent

ratio

n (

Con

cent

ratio

n ( µµ

g PC

E / g

soi

l)g

PCE

/ g s

oil)

DNAPL

* Port height above base* Port height above base

0

5,000

10,000

15,000

20,000

25,000

0 200 400 600 800 1000 1200

Shallow Port (17 cm*) Central Port (11 cm*) Deep Port (4 cm*) Average

Cell 2 (5% Fe) PCE Concentrations

Cell 2 (5% Fe) Cell 2 (5% Fe)PCE ConcentrationsPCE Concentrations

Elapsed Time (days)Elapsed Time (days)

DNAPL

Con

cent

ratio

n (

Con

cent

ratio

n ( µµ

g PC

E / g

soi

l)g

PCE

/ g s

oil)

70% removed70% removed70% removed

* Port height above base* Port height above base

0

5,000

10,000

15,000

20,000

25,000

0 200 400 600 800 1000 1200

Shallow Port (18 cm*) Central Port (11 cm*) Deep Port (4 cm*) Average

Cell 3 (10% Fe)PCE Concentrations

Cell 3 (10% Fe)Cell 3 (10% Fe)PCE ConcentrationsPCE Concentrations

Elapsed Time (days)Elapsed Time (days)

DNAPL Con

cent

ratio

n (

Con

cent

ratio

n ( µµ

g PC

E / g

soi

l)g

PCE

/ g s

oil)

96% removed96% removed96% removed

* Port height above base* Port height above base

0

10,000

20,000

30,000

40,000

50,000

0 200 400 600 800 1000 1200

Cell 1 Cell 2 Cell 3

Chloride ConcentrationsChloride ConcentrationsChloride Concentrations

Elapsed Time (days)Elapsed Time (days)

Con

cent

ratio

n (

Con

cent

ratio

n ( m

g/l

mg/

l ))

0% iron0% iron

5% iron5% iron

10% iron10% iron

Organic Degradation ProductsOrganic Degradation ProductsOrganic Degradation Products

•• Total degradation products measured less than Total degradation products measured less than 1% of original PCE added to cells1% of original PCE added to cells

•• TCE was main product detected (<100 TCE was main product detected (<100 µµg/g soil)g/g soil)

•• DCE isomers generally less than 2 DCE isomers generally less than 2 µµg/g soil, but g/g soil, but showed regular trendsshowed regular trends

•• VC only detected briefly in cells with ironVC only detected briefly in cells with iron –– None detected at end of experimentNone detected at end of experiment

Conclusions: Laboratory Experiments

Conclusions:Conclusions: Laboratory ExperimentsLaboratory Experiments

Batch experiment:Batch experiment: •• Batch experiment showed that concept is Batch experiment showed that concept is

viableviable

•• HalfHalf--life was relatively low, possibly due to life was relatively low, possibly due to continuous mixing ofcontinuous mixing of hypovialshypovials

Cell experiment:Cell experiment:

•• Experiment using larger cells showed Experiment using larger cells showed removal of more significant amounts of freeremoval of more significant amounts of free--phase PCEphase PCE

Conclusions: Field Demonstration

Conclusions:Conclusions: Field DemonstrationField Demonstration

•• Degradation of PCE was apparent, despite Degradation of PCE was apparent, despite limited DNAPL and irregularity of limited DNAPL and irregularity of degradation productsdegradation products

•• Longer halfLonger half--life due to static conditions of life due to static conditions of testtest

•• Field testing at a larger scale with Field testing at a larger scale with commercial soilcommercial soil--mixing equipment mixing equipment appears to be warrantedappears to be warranted

AcknowledgementsAcknowledgementsAcknowledgements

NSERC / Motorola / EnviroMetal TechnologiesNSERC / Motorola / EnviroMetal Technologies Industrial Research Chair in Groundwater RemediationIndustrial Research Chair in Groundwater Remediation

GeomatrixGeomatrix Graduate ScholarshipGraduate Scholarship

The Gillham GroupThe Gillham Group Greg Friday, Wayne NobleGreg Friday, Wayne Noble

Others in the field and laboratoryOthers in the field and laboratory Paul Johnson, Paul Johnson, IngletonIngleton, Mike , Mike PollicePollice, Sam Vales, Sam Vales

Iain Iain McIlwraithMcIlwraith, , AlpaAlpa JadejaJadeja, Geoffrey , Geoffrey OkwiOkwi Bob Bob