Case Study: Permanganate Applied to VOCs in Fractured Shale · 1 Case Study: Permanganate Applied...

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Case Study:Permanganate Applied to VOCs

in Fractured ShaleBeth L. Parker, Ph.D.Beth L. Parker, Ph.D.Department of Earth Sciences

University of Waterloo

Presented at the EPA Symposium in ChicagoDecember 12, 2002

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Research Collaborators� Dr. Tom Al

� University of New Brunswick� Dr. Ulrich Mayer

� University of British Columbia� Drs. Ramon Aravena and John Cherry

� University of Waterloo� Kenneth Goldstein, CGWP

� Malcolm Pirnie, Inc� Grant Anderson, P.G.

� U.S. Army Corps of Engineers

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Watervliet Arsenalin New York State

Watervliet Arsenal

TroyHudson River

Shale

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Hudson River

Watervliet ArsenalBuilding 40 Area

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FlowOverburden

Bedrock

PCE

adapted from Mackay and Cherry, 1989

DNAPLDNAPL Passed Through Overburden Into Shale

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The Problem

� Chlorinated ethenes � as high as 150 mg/L

� Contamination down to 150 ft. bgs

� All VOC mass in fractured shale

� AOC is 200 ft west of Hudson River

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Study Area

AW-MW-59

N

Building 40

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Identification of Major TransmissiveZones Using Hydro-geophysics

USGS, 2001

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Major Transmissive Zone Identified

USG

S, 2

001

10

93,600

5,310

5,150

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MW-71

Fractures, Transmissive Zones, and Total VOCs from PACKER TESTINGPACKER TESTING

Leakage

µg/L

USGS, 200110

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PCE and Degradation Products in Shale

South North

From packer test intervalsduring drilling

PCE

DCE

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Interconnected Fracture Networkwith Two Major Transmissive Zones

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Cross-section view

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DNAPL was Initially Distributedin Many Fractures

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ILLUSTRATION OF MATRIX POROSITY

A

Microscopicview of rock

matrix

mineral particleDETAIL A

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DNAPL Phase Initially Resides within Fractures

Fracture Aperture2b

Fracture Spacing

H O2

φfφm DNAPL

Matrix porosity is1000 times greater than

fracture porosity

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DNAPL Disappearance by DiffusionParker et al. (1994)

Fracture Aperture2b

FractureSpacing

φfφm

H O2

DNAPLφf φm

DissolvedPhase

φfφm

DissolvedPhase

Early Intermediate Later Time

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Snake Hill Shale FormationWatervliet Site

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Core Hole In Source Zone

vadosezone

groundwaterzone

coredhole

B.L. Parker, 200018

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Diffusion Into Rock Matrix

Porous Rock Matrix

DiffusionHalo

Fracture

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0 1 10 100TCE mg/L

rock core

non-detect

Fractures withTCE migration

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fractures coresamplesanalyzed

cored hole

Core Sampling forMigration Pathway Identification

B.L. Parker, 200020

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Core Diameter3.2 Inches

Sample Length~Two InchesOverview

of theRock Core

Method

Parker and Colleagues 199721

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Two Rock CrushersTwo Rock Crushers

Rock Crusher

Crushing Cell

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MW-74Dec. 2001 (preliminary data)

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10

20

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40

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60

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90

100

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150

1600.01 0.1 1 10 100 1000 10000 10000

01E+06

conc. VOC (ug/L)

dept

h (ft

)

PCETCEc-DCE

PCE

solu

bilit

y (2

40 m

g/L)

Rock CoreProfileDec 2001

Pre-KMnO4Injection

CMT AqueousPORTS Concentrations

(Feb. 2002)

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PCE � 8 ug/LTCE � 5 ug/Lc-DCE � 350 ug/L

PCE � 4 ug/LTCE � NDc-DCE � 1088 ug/L

PCE � 458 ug/LTCE � 123 ug/Lc-DCE � 2802 ug/LPCE � 9183 ug/LTCE � 382 ug/Lc-DCE � 524 ug/LPCE � 13,988 ug/LTCE � 3,699 ug/Lc-DCE � 15,155 ug/LPCE � 172 ug/LTCE � 259ug/Lc-DCE � 11,745 ug/L

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WESTBAY ® MP SYSTEM

2.5 ft.

2.5 ft.

Tripod

Cable ReelPressure Probe

Sample Bottle

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SOLINST CMT ® SYSTEM

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Site Conceptual Model

� VOC migration occurs in a large number of interconnected fractures

� Nearly all VOC mass resides in the rock matrix rather than in the fractures

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It is well established that permanganate completely

destroys chlorinated ethenes

However, to do so,it must be delivered to the

contaminant mass

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Can permanganate be effective for remediatingchlorinated ethenes in

fractured sedimentary rock?

Important factors:� Delivery throughout fracture network� Diffusion rates into rock matrix� Oxidant Demand of Shale

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KMnO4 Injections at Watervliet

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Potassium Permanganate Injection597675 65 34

~145 feet bgs

Phase 1Phase 1injectioninjection

Phase 2Phase 2injectioninjection

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PILOT STUDY RESULTS in 2002

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Treatment Approach Permanganate

� Permanganate oxidizes chlorinated ethenes

Solvent + MnO4- MnO2(s) + Cl- + Acid

� 13C / 12C and Chloride used to confirm destruction

� Stable chemistry in subsurface allows time for diffusion into matrix

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Remediation in Fractured Porous Media

Treatment zone

EarlyTime

LaterTime

KMnO4 in fracture

Contaminated clay/rock

Contaminated clay/rock

B.L. Parker, 1993

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In Situ Oxidation in Fractured Porous Media

� Diffusion of both reactants occurs in opposite directions

� Readily destroys sorbed phase contaminants

Greatly reduces time scale for remediation

B.L. Parker, 1993

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Analogy to Fractured Shale

Results from Permanganate Field Tests

in Marine Clay

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Oxidized zone shows extent of diffusion invasion and treatment by KMnO4

B.L. Parker, 1996

Invasion frontTop of clay

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3.8

3.9

4.0

4.10 5 10 15

KMnO4 in pore water (g/l)

Depth(m)

147 daysPease ISI-6

KMnO4 Profile in Clay

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Combined Profiles in Clay

3.8

3.9

4.0

4.10 5 10 15

Concentration

Depth(m) KMnO4

TCE

147 daysPease ISI-6

Reaction interface

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Snake Hill Shale FormationWatervliet Site

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Permanganate Diffusion into Matrix from Fracture

z

x

y

diffusion

2b = fracture aperture

mass mass

x x+

C/Co

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Elemental Manganese Profiles in ShaleTransects Normal to Fractures Propagating

in from Surface of Rock Sample

0

500000

1000000

1500000

2000000

2500000

0 0.2 0.4 0.6 0.8 1 1.2

Distance (mm)

Transect #1

Transect #2

Fracture

Fracture

Shale sample in 10 g/L KMnO4 solution for ~6 weeks

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How long will MnO4 take to remediate the source zone?

� Answer being sought using~ field data~ laboratory tests~ numerical models

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Preliminary MIN3P SimulationsWatervliet Arsenal

3D multicomponent reactive transport model

Model developed byDr. Ulrich Mayer (1999)

Now being modified for permanganate oxidation

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MIN3P Simulation

� Simulate 1D MnO4- invasion into shale matrix

where PCE has been diffusing in for 40 years to examine rates of matrix clean-up

� Parameters:� Site-specific φ, De, foc� MnO4

- R = 1� PCE R = 220 (estimated using foc=0.5%)� Source [ PCE ] = 150 mg/L for 40 years� Injection [ KMnO4 ] = 5 g/L

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Chloride Diffusion Test Cell for Rock

Golder Associates, Toronto45

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Initial Condition40 years PCE Diffusion-In

MIN3P Model � Snake Hill Shale

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Matrix Profiles after 1 yearMnO4

- InjectionMIN3P Model � Snake Hill Shale

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Matrix Profiles after 2 yearsMnO4

- InjectionMIN3P Model � Snake Hill Shale

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Matrix Profiles after 5 yearsMnO4

- InjectionMIN3P Model � Snake Hill Shale

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Partial Mass Destruction

Greatly diminishes VOC mass flux into fracture network

after permanganate is gone

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PCE flux to fracture afterpartial permanganate treatment

Frac3DVS Modeling Log - Log Scale

0.001

0.01

0.1

1

10

0.001 0.01 0.1 1 10 100

Time (years)

Flushing only1 yr2 yr5 yr10 yr20 yr

KMnO4

RemediationTimes

No MnO4 Case

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Preliminary Conclusions

Permanganate�

� Diffuses and reacts in low K matrix

� Prevents release of mass from matrix to flowing

groundwater while present in fractures

� Greatly reduces magnitude of flux from matrix

even after partial treatment

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How do we know that VOCsare being destroyed ?

� Chloride increases at many locations

� Change in carbon isotope ratio of PCE

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ON-GOING WORK

� Rebound monitoring after pilot injections

� Permanganate invasion tests� Laboratory samples� Field cores

� Reactive transport modeling� Single fractures and fracture networks

� Design of full-scale system and monitoring

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Acknowledgements� Project Contributors:

~ Steven Chapman and Martin Guilbeault (UWaterloo)~ Daria Navon and Andrew Vitolins (Malcolm Pirnie)~ Stephen Wood (U.S. Army Corps of Engineers)~ JoAnn Kellogg (Watervliet Arsenal)~ John Williams and Fred Paillet (U.S.G.S)

� Funding:~ U.S. Army Corps of Engineers~ Solvents-In-Groundwater Research Program

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The End