INFLUENCE OF UPWARD WATER FLOW ON DOWNWARD DNAPL

MIGRATION THROUGH A ROCK FRACTURE NETWORK

A thesis submitted to the Department of Civil Engineering

in conformity with the requirements for the degree of

Master of Science (Engineering)

Queen's University

Kingston, Ontario, Canada

September, 1997

copyright O Joanne Jennifer M&, 1997

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Laboratory experiments were performed in which upward hydraulic gradients were

applied across a rock h t u r e network to anest the downward flow of dense non-aqueous

phase liquid (DNAPL). Tetmchloroethylene @CE) was pooled above a hctured

limestone block at varying heights, while a hydraulic gradient was applied across the rock

sample. The effect of PCE pool height on the arresting m e n t was examined as well as

the effect of decreasing interfacial tension between the fiuids. Pooling above the hc ture

was done both with and without a porous medium present to simulate an aquiferhedrock

situation and a lagoon scenario, respectively. For a given pool height, the corresponding

arresting gradients for drainage nuis were smder than the gradients necessas, to halt

flow during wetting m. Drainage and wetting pairs displayed a hysteretic relationship

consistent with the hdings of previous studies for a single hcture.

For larger pool heights, PCE was able to enter into the kture network against higher

upward gradients. Cornparison of runs both with and without a porous medium present

above the rock sample showed that maximum PCE f3ow rates and arresting gradients

were greater for the case of a porous medium present. When the interfacial tension

between the fluid phases was decreased in the porous medium mm, the maximum PCE

flow rates and the arrestïng upward hydraulic gradients inmeased under similar pool

heights. Competing effects of multiple hctures do not appear to facilitate downward

migration cf PCE concurrent with upward water flow.

ACKNOWLEDGEMENTS

This thesis waç supported by the Solvents in Grouodwater Consortium which receives

funding fiom Boeing, Ciba-Geigy, Eastman Kodak, General Electric, Motorola, PPG

Industries and United Technologies Corporation. Additional support was provided

through a strategic gant by the Naturai Science and Engineering Research Council

WSERC) of Canada to B.H. Kueper for hctured rock studies, and by Queen7s

University at Kingston, Ontario in the form of shident scholarships. Witco Corporation

donated the surfactant used in this research.

Many th& are extended to Dr. Bernard Kueper for his excellent guidance,

encouragement and understanding during this research study. Technical support provided

by James Roettger, David Tryon, Richard Momson and Lloyd Rhymer is gratefülly

acknowledged.

The author is indebted to Anthony Brown as well as to Sniart Lunn, Bettina Longino,

Carol Mothersiil, and Julie Konzuk for their accornpaniment during the marathon

experimental work carrïed out and to Jason Gerhard for editing. The N 1 tirne and

honourary 'DNAPL cave' inhabitants are thanked profusely for their ready han&,

continued input and interest. To dl of rny family and fiiends, their encouragement and

good humour were greatiy appreciated. Very special thanks to David Hill for his positive

moral support in this undertaking, especially in the £inal stages of writing. This thesis is

dedicated to my mother, Dolores Muzzin.

FOREWORD

This thesis has been written such that chapters 1 and 2 contain the introduction and

Iiteraîure review, respectively, in traditional thesis fom. Chapter 3 has been witten as a

self-contained manuscript which will be submitted for publication after the thesis

defence. Concluding comments and recommendations are presented in Chapter 4. Data

fiom dl runs conducted, data plots, and regression analyses which were not included in

the main body of the thesis are provided in the appendices.

TABLE OF CONTENTS

............................................................................ 3.3.2 Materials ................... ... 4 0

......................................................................... ................... 3.3.3 System design .. 1 5

.......................................................................... ..... 3.3.4 Testing procedures ... -50

............................................................................ 3.3.5 Interfacial tension reduction -53

3.4 RESULTS AND DISCUSSION ........................................................................................ 57

................................................... ............................. 3.4.1 Permeability testing .... 57

............................................................................... 3.4.2 PCE pool height variation 6 2

............................................................ ................. 3.4.3 Pooling in porous media .. -68

........................................................................................................... 3.5 CONCLU~IONS 72

............................................................................................................. 3.6 REFERENCES 74

4 CONCLUSIONS AMI RECOMMENDATIONS. ....................a....................... o.aaoaaoa76

.......................................................................................................... 4.1 CONCLUSIONS 76

.............................................................................................. 4.2 RECOMMENDATIONS -77

..... APPEN'DM A - INTERFACIAL TENSION AND SURFACE TENSION MEASUREMENTS 80

APPENDIX B - SINGLE-PHASE FLOW TEST &SUL= ..a..a~....oa.maoo.amaoaoo.oaoaa..aa.o.oo ..o.a.oaa83

.......................... APPENDIX C - DATA FROM TWO-PHASE FLOW TESTS RUNS #1-15 .86

..................................... APPENDIX D - LINEAR REGRESSION DATA 0.0...0.........0aa......152

............................................................... APPENDK E - FRACTURE NETWORK MAP ...157

LIST OF TABLES

Table 111 - Most common c o n ~ t s found at Superfund sites in the United States (Agency for Toxic Substances and Disease Registry, U.S. EPA Pnority List,

Table 1.2 - Maximum concentration limits (MCL) of common DNAPLs, solubility in water, and order of magnitude difference between these values (fiom p h w and chev, 1996). .......................................................................... 5

Table 3.1 - Physical and chernical properties of te~hloroethylene-------------------------=- 46

Table 3.2 - Configuration of experimentd -. ............................................................... 52

Table 3.3 - Physical and chemical properties of polyoxyethylene sorbitan ester; trade name Witconol FLO MO SMO-20 (Witco Corporation Materid Safety Data Sheet, 1997). ................................................................................................. 54

Table 3.5 - PCE-water interfacial tension of injected solutions at 24°C.---.-------..---.---.--.- 55

Table 3.6 - Caiculated entry pressure apertures using hydraulic gradients before and at initial PCE flow for dl runs performed under drainage conditions with no porous me&um present ................................................................................ 61

Table A.1 - Surface tension measurements for 2% polyoxyethylene sorbitan ester solution ....................................................................................................... 8 1

Table A.2 - Interfacial tension measurements for 2% polyoxyethylene sorbitan ester-PCE system. ....................................................................................................... - 8 1

Table A.3 - Surface tension measurements for polyoxyethylene sorbitan estedethmol solution in a 1 :5 weightpercent ratio .......................................................... 82

Table A.4 - Lnterfacial tension rneasurements for polyoxyethylene sorbitan ester/ethanol solution in a 1 5 weight percent ratio with PCE. ........................................ ..82

vii

Table C. 1 - Data fiom nin # 1; 35 mm pool height under primary drainage condition~---8~

Table C.2 - Data kom run #2; 85 mm pool height under drainage conditions -----.-----------94

Table C .3 - Data fiom nin #3; 85 mm pool height under wetting conditions *.------------.-.--99

Table C.4 - Data nom nui #4; 60 mm pool height under drainage conditions --.------------105

Table CS - Data fkom nui #5; 60 mm pool height under wetting conditions ----.---*-----.-J 10

Table C.6 - Data from nui #6; 100 mm pool height under drainage conditions .--------=.--114

Table C.7 - Data fiom run #7; 100 mm pool height under wettùig conditions.--------------11*

Table C.8 - Data fiom nui #8; 1 15 mm pool height under drainage conditions - - - - * - - - - - - - . 120

Table C.9 - Data fiom run #9; 1 15 mm pool height under wetting conditions --.---------.-.124

Table C. 10 - Data fiom run #IO; 85 mm pool height in sand under ................................................................................... drainage con&ions -1 28

Table C. 1 1 - Data fiom run #I l ; 85 mm pool height in sand under .................................................................................... wemg 1 3 1

Table C . 12 - Data fiom nin # 12; 85 mm pool height in sand under &ainage conditions .................................................................................... 136

Table C.13 - Data fiom nui #13; 85 mm pool height in sand under wetiing conditions ..................................................................................... 138

Table C .14 - Data ffom run # 1 4; 85 mm pool height in sand under drainage conditions.. ....................................................................... 1 4 4

Table C. 15 - Data fiom nui #15; 85 mm pool height in sand under Wetting conditions ..................................................................................... 146

viii

LIST OF FIGURES

Figure 1.1 - Pore scale interface of DNAPL and water, where DNAPL is non-wetting ................................................ wfi respect to water on the fr;icme 6

Figure 1.2 - Typical DNAPL contamination scenario (fiom Chown et al., 199 7). - - O - - - O - - - - IO

Figure 1.3 - Remediation by chernical flooding and hydraulic bottom creation to prevent downward mobilization (fiom Chown et 1997). ..................................... I I

Figure 3.1 - Limestone sample after hcturing has occurred; confïned with nylon banding to prevent firacme disnubance. ..................................................................... 43

Figure 3.2 - Schematic of fiacture network, mapped fiom traces on six outer sides (scale ........................................................ 1 :4, dimensions &own in millimetres). 44

Figure 3.3 - Upward hydraulic gradient flow system (not to scale; dimensions shown in .................................................................................................. rniUimetres). 48

Figure 3.4 - Interfacial tension versus polyoxyethylene sorbitan ester concentration.---56

Figure 3 -5 - Interfacial tension versus surfactan~ethanol concentration.----------------.----*- 56

Figure 3.6 - Effective hydraulic aperture versus Reynolds number for prelirninary hydraulic flow tests. .................................................................................. 59

Figure 3.7 - Cumulative PCE volume versus t h e for a 100 mm pool height under drainage and imbibition conditions. Arrows indicate Vh change of 0.05. .......................................................................................... 63

Figure 3.8 - Combined plot of PCE flow rates at each upward hydraulic gradient applied for pool heights of 35,60,85, 100, and 115 mm; "D" denotes drainage m,

............................................................................. "w' denotes wetting m.. 67

Figure 3.9 - PCE flow rate vernis upward hydraulic gradient for pool height of 85 mm in porous media (#16 silica sand) at interfacial tensions of 0.029, 0.0075, and 0.0050 .... - ........-. ..... -- ..............-. - ............................ ..--.....-...- .......... * .... .. 71

Figure C. 1 - Cumulative PCE flow for run #1, 35 mm pool height under primary drainage tondions ..... -...- ....... - ..... -..-.. .... - ....... . . . .......... . . 90

Figure C.2 - Cumulative PCE flow for run #2, 85 mm pool height under drauiage conditions ......... ..... .-........ ........ .- . . . . . . . . . . . . . . . . . . . 96

Figure C.3 - Cumulative PCE flow for nin #3, 85 mm pool height under wetting conditions .....-...-.. .. .. ..... -. ... ......... . . . . . . . . . . . . . . . . . . . . . . . . . 1 O 1

Figure C.4 - Cumulative PCE flow for run #4/#5,60 mm pool height under drainage and wetting conditions .... .. .. .. .. .. . .-. .... .. .-. .. .- ...... .. . . . . . . . . . . . . . . . . . . . 1 12

Figure C.5 - Cumulative PCE flow for nin #8/#9, 115 mm pool height under drainage and w e h g . . . . . . -. . . . ... . . . . .-. . .. .. . .. . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 1 26

Figure C.6 - Cumulative PCE flow for nm #10/#11, 85 mm pool height in sand under drainage and wehg conditions......- ......... -.S..-...-..-.-.......---..... . . . . 133

Figure C.7 - Cumulative PCE flow for run #12/#13,85 mm pool height in sand with 2% polyoxyethylene sorbitan ester solution under drainage and wetting

.... .. .. ........ .. .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

Figure C.8 - Cumulative PCE flow for run #14/#15,85 mm pool height in sand with 12% surfactant/euianol solution under drainage and wetting conditions ...- ..... . ..... - .... . ..... - ........... ..................... ........ ... ........ -.... ............. 148

NOTATION

Mean asperity height in hcture p]

Maximum asperity height in hcture [LI

Height of water above fkicture &]

Half of the fhcture separation distance [LI

Height of DNAPL above h c t u r e &]

Hydraulic diameter of fkacture, pipe or channel [LI

Fracture aperture p]

Effective hcture aperture IL]

Gravitational acceleration [L-T~]

Hydraulic gradient [dimensionless]

Hydraulic head at the top of the fracture &J

H y draulic conductivity [LT']

Verticai fjtacture length [LI

Capillary pressure F-L-~]

Entry pressure PL-~]

Non-wening phase pressure [FL-~]

Wetting phase pressure @?.L-~]

Specific discharge [L-T']

Fluid flow rate p3T']

Reynolds nurnber [dimensionless]

xii

Relative roughness factor [dimensionless]

Effective fiachire width [LI

Cubic law hydradic aperture IL]

Mean asperity height F]

Dynamic viscosity W-L~'-T']

Contact angle [O]

Wetting phase density W-L-']

Non-wetting phase density WL-~]

Interfacial tension [F-L" ]

The availability and quality of potable water supplies has traditionaily influenced the

location of human settlements and the health of these populations. In countries such as

Canada, where surface water is generally in great abundance, Iittle attention was given to

the impact that industnalization was having on water quality. As taste and odour

problems in surface drinking water emerged in the late 19607s, concern for clean drinking

water increased. Groundwater quality issues and regdation emerged in the late 1970's

(Pankow and Cherry, 1996). Although only estimated to compose 0.6% of the earth's

hydrologic budget, groundwater comprises 95% of the world7s fiesh water supply (Freeze

and Cherry, 1979).

The industrial revolution initiated both an increase in human population and an increase

in the production of xenobiotic compounds; these two factors contributed to degrade

water supplies and contaminate soi1 and water through unsustainable practices. Pesticide

use, sewage disposal, leaking underground tanks and pipelines, improper waste disposal,

and chemical spills have adversely affected our potable water supplies. These

anthropogenic inputs progressed unchecked for a number of years before actions were

taken to stem this tide of irresponsible resource management.

Water quality objectives in Canada prior to 1984 were not established with any

consistency on a federal level until the Canadian Water Quaiity Guidelines were produced

as an effort by the Canadian Council of Resource and Environment Ministers (later the

Canadian Council of Ministers of the Environment, CCME) to hamonize objectives.

The CCME estunated that approximately one quarter of Canadians rely on groundwater

for drinking water and livestock watering purposes (CCME, 1993).

Dense non-aqueous phase liquids @NAPLs), such as chlorinated solvents, creosotes and

cod tar, are common groundwater contaminants in the industnalized world and among

the most detrimental to human health (Mackay and Cherry, 1989). These are of particular

concem because of their ability to migrate through the subsuface a great distance from

their origuial source. Many of these compounds are now known or suspected

carcinogens. The widespread presence of nonaqueous phase liquids (NAPLs) in the

subsurface, discovered in the past two decades, sparked the introduction of better

handling and disposal methods. In the United States, legislators responded by enacting

CERCLA (Comprehensive Environmental Response, Compensation and Liability Act,

also known as Superfimd) which created a national priority list (NPL) of sites that

required hanediate attention. Table 1.1 lists the most common groundwater

contaminants found in North America and their relative rating as 'hazardous' to human

health, according to the U.S. Enviro~mentai Protection Agency.

Prior to the 19807s, Chernicd Safety Data Sheets produced by the Manufacturers

Chemists Association, and degreasing guidelines produced by the Amencan Society for

Testing and Materials (ASTM), instmcted chlorinated solvent users to dispose of these

compounds by distributhg them ont0 the ground or into unlined lagoon-type ponds

Table 1.1 - Most cornmon contaminants found at Superfund sites in the United States (Agency for Toric Substances and Disease Registry, U.S. EPA Priority List, 1995).

Rank of top 20 Substance hslardom NAPL?

Acetone

Barium

Benzene 5

Cadmium 7

1 DDT, DDE, DDD 11,19 1

1 Methyiene Chloride Y 1 1 Nickel 1 1 Pentachlorophenol 1

1 Toiuene 1

1 Vinyl Chhide 4 Y I 1 zinc I

(Pankow and Cherry, 1996). Improved guidelines for the handiing of many of these

immiscible compounds were introduced when the extent of contamination and difficulty

of mass retrieval was discovered in the early 1980's. As well, the toxicological effects of

dissolved concentrations of some DNAPLs were beginning to be recognized during this

t h e period.

Despite the relatively low aqueous solubilities of DNAPLs, dissolved concentrations in

groundwater can be many ordes of magnitude above drinking water limits (see Table

1.2). Thus, a small amount of immiscible liquid trapped in a porous medium can be

capable of generating a large volume of contaminated groundwater. Mackay and Cherry

(1989) provide data from well-documented sites where plume delineation and source

zone investigations have occurred; for example, a 1500 litre pure-phase DNAPL release

in a sand and grave1 aquifer in Cape Cod, U.S.A. caused a dissolved phase groundwater

plume of an estimated 40 billion litres. This is not an uncornmon scale of contamination

at sites where significant volumes of DNAPLs have been released.

Migration of these NAPL compounds into the ground proceeds through surficial soils

and, if the source strength is great enough, below the watertable to underlying geologic

formations. These relatively low-solubility fluids wiil travel as a virtually immiscible

phase to water through pore throats and hcture openings dictated by the small scale

structures they encounter.

Table 1.2 - Maximum concenîration limits (MCL) of common DNAPLs, solubility in water, and order of magnitude difference between these values (from Pankow and Cherry, 1996).

As a DNAPL migrates into the subsurface and below the watertable, it must displace the

water-filled pores that it encountea. The relative amounts of DNAPL and water in any

location wil1 be dependant on the pressure distribution between the two fluids. When two

immiscible liquid phases are in contact with one another, a boundaq exists which

separates these phases (see Figure 1.1). The molecules present on either side of this

boundary are attracted to their respective phases in the bulk liquid, due to cohesional

forces, causing the boundary to be in a state of tension. The liquid having a greater

pressure associated with it will be exerting a larger force on the boundary and causing a

convex fluid shape which minimizes the surface area of the interface; conversely, the

lower pressure phase will f o m a concave shape at the interface.

Fracture W a11 (s)

Figure 1.1 - Pore scale interface of DNAPL and water, where DNAPL is non- wetting with respect to water on the fracture surface.

In a system consisting of two phases and a solid surface, the interaction of these three

entities wiII result in one phase displaying a preferential affkity to the solid (see Figure

1.1). The phase forming an angle of contact, 8, on the solid which is less than 90" is

termed the wetting phase; perfectly wetting conditions exist when the contact angle is

zero and the phase envelops the fracture surface or minera1 grain. Non-wetting fluids. or

fluids which do not coat solid surfaces, exist at higher pressures than wetting fluids in

two phase systems.

Capillary pressure is defined as the difference in non-wetting and wetting phase pressures

which exist across the fluid-fluid interface:

where Pc is the capillary pressure, PNW is the non-wetting phase pressure, and Pw is the

wetting phase pressure. The capillary pressure is related to the saturation of the system

on a macroscopic scale. Reitsma and Kueper (1994) measured this relationship in a

rough-wailed rock hcture and obtained a good fit to the experimental data by using a

Brooks-Corey porous media capillary pressure fünction (Brooks and Corey, 1966). This

porous media equivalent was a valid relationship to apply due to the variable nature of the

h c t u r e opening. The distribution of aperhue values found dong a hcture plane is

analagous to the distribution of pore throat sizes in a porous medium.

The capillary pressure which must be exceeded for the DNAPL phase to enter a fracture

opening, or the entry pressure (PE), for a given system will depend on the interfaciai

tension, local fkcture aperture, and the wettability characteristics of the fluids and solid

invoived. Migration of DNAPLs throua frachired media wiil be dictated by the capillary

pressure at the advancing fluid edge. The entry pressure for a fiachue may be defined for

different locations dong the length of a natural £facture, where the aperture and the

aperture geometry will Vary. The entry capillary pressure required for a DNAPL to enter

into an initially water saturated fkcture is given by (Kueper and McWhorter, 199 1):

where G is the interfacial tension between the two liquids, 0 is the contact angle, assumed

to be zero for a perfectly wening situation, and e is the fiachire aperture. Therefore, for

capillary pressures greater than the entry pressure, DNAPL will enter into the fracture.

For practical applications, some form of effective hcture aperture is estimated from

available data and the most conservative hcture opening geometry is utilized.

If released in sufncient amounts, the pressure of the DNAPL phase can induce migration

in lateral and vertical orientations through surface deposits and in formations well below

the watertable. The actual path that the immiscible phase will take is dependent on the

capillary pressure distribution throughout the interface and therefore a function of pore

b o a t size. Using a two-dimensionai numerical rnodel, Kueper and Gerhard (1995)

reveal dramatic variation in DNAPL migration and lateral spreading patterns based only

on the release location in a single heterogeneous porous media aquifer. Furthemiore, a

field snidy by Podsen and Kueper (1992) involving a controlled release of PCE in a

quatemary sandy deposit illustrates that DNAPL migration occurs dong very small-scale

depositional layers. For these reasonç, it is not possible to predict the exact locations of

pure-phase contaminant &er a spi11 has occurred.

Historically, many bedrock units were assumed to be 'impermeable' and a lower limit of

DNAPL travel was expected. The discovery that many of these units contained hctures,

which allowed significant travel of pure-phase contaminant, focussed new attention on

better defining 'very low' permeability clays and rock. Near surface clays that have

undergone alteration or possible dessication are capable of transporting DNAPLs to

deeper units, possibly aquifers used for water supply. Fractured rock or clay formations

will facilitate the downward travel of DNAPL through fractures, providing the capillary

pressure at the leading edge of the DNAPL body exceeds the entry pressure required to

invade the largest apertures present in the unit. In the pst, hctures on the order of tens

of microns were considered to inhibit the flow of DNAPLS, however, field and laboratory

investigations now indicate that DNAPLs may travel significant distances through these

conduits on short time scales (Kueper and McWhorter, 1991). Since hcture volumes are

relatively small, travel of contamhants over large distances is feasible.

Detemiining the bulk hydraulic conductivity of a hctured rock mass can be

accomplished in field situations, however, resolving the specific flow conduits available

for hansport is not readily available fiom surface or sub-dace m e y data. Fracture

density, orientation, and average trace length can be determined through examination of

surface expressions of these feaîures. Downhole methods such as acoustic televiewer,

borehole video, and borehole flowmeter provide similar data

Dead-end hctures in rock can result in a significant portion of NAPL mass that cannot

be accessed by traditional water and chernical floods. In light non-aqueous phase liquid

(LNAPL), and some rare DNAPL scenatios, blast fkacturing of low permeability, highly

contarninated units has been canied out to both increase hydraulic conductivity and

accessibility to contaminant mass (Loney et al., 1996). Loss of mass by diffusion into

porous matrix blocks as a result of concentration gradients can also occur over t h e .

Dual porosity models have been developed in the oil industry literature where the porous

reservoir contribution is significant in relation to the total oil phase recovery. Sorption to

fracture walls is also problematic with respect to mass recovery, especially in materials

with charged surfaces such as clays.

Residud DNAPL (that which exists as disconnected blobs and ganglia) poses a

formidable challenge in terms of mass recovery. These small, isolateci, pure-phase blobs

are trapped by capillary forces in frafture charnels or pore throats. This implies that a

10

significant mass quantity is immobile and may act as a long term source for the creation

of dissolved plumes as groundwater nows through a residual zone.

chernical flood recovery

LC reiease + IN-

d

fractured \ aquitard

clay

Figure 1.2 - Typical DNAPL contamination scenario (from Cho~vn et ai., 1997).

Use of water or chemical flooding technologies have been attempted in laboratory and

field situations. Alteration of various physical and chemical properties. such as

interfacial tension, density, and solubi1ity can mobilize DNAPL to other locations in a

stratigraphie section. Figure 1.2 shows a typical DNAPL contamination scenario where a

release at surface has migrated through various geological units afier a chemical flood.

Major restrictions on effective mass recovery from these chemical flooding rnethods in

field applications are aquifer heterogeneity, mass transfer limitations and low chemical

solubilities. A large concem is the possibility of remobilizing a DNAPL pool downwards

and worsening the extent of the contamination. Horizontal well installation and creation

of an 'hydraulic bottom' under a proposed chemical flood was put forth by Kueper and

McWhorter ( 1 991), see Figure 1.3. Creation of harmful by-products fiom flooding

technoiogy is also a concem. Currently, long term commitrnents to pump-and-treat

systems are required to capture dissolved phase plumes or recover NAPL.

lower aquifer

Figure 1.3 - Remcdiation by chemical flooding and hydraulic bottorn creation to prevent downward mobilization (from Chown et al., 1997).

This research was undertaken to inves tigate two-phase flow of tetrachloroethylene ( PC E).

a cornmon DNAPL, and water in a rough-wailed fracture network by simulating two

comrnonly encountered contamination scenarios in fractured rock formations. The

primary objective of this thesis was to examine the abiiity of upward hydraulic gradients

to arrest the downward migration of DNAPL through a fracture network. An upward

hydraulic gradient is defined here as providing upward water flow. Although this

defuition is not strictly correct, it provides a convenient working mode1 for practical

applications.

Cmently, there is a distinct lack of labonttory data, and detailed field data, which

describes the behaviour of two fluid phases in the presence of multiple, cross-cutting,

realistic fractures. A second objective of this study is to examine the effects of cross-

cuttuig multiple hctures on two-phase flow. The third objective of this study exarnined

the alteration of certain parameten on the rates of DNAPL migration through fiacnire

networks, including variation of the DNAPL driving force and interfacial tension

decreases between phases. Gathering laboratory-scale data of phase interactions in a

fracture network is a necessary exercise that wilI expand the current understanding of

these systems. This shidy addresses pure-phase tetrachloroethylene and aqueous phases,

and does not investigate the dissolved and sorbed concentrations of PCE. The

implications of these assumptions are minor with respect to the stated objectives and are

discussed in Chapter 3.

1.1 References

Brooks, R.H. and A.T. Corey, 1966. Properties of Porous Media Affecting Fluid Flow. Jownal of the Irrigation and Drainage Division, Proceedings of the American Society of Civil Engineers, 6 1 -8 8.

Canadian Council of Resource and Environment Ministers, 1 993. Canadian water qualiiy guidelines, Water Quality Branch Inland Waters Directorate, Ottawa, Ontario.

Chown, J.C., B.H. Kueper and D.B. Mcwborter, 1997. The use of upward hydraulic gradients to arred downward DNAPL migration in rock hctures, Submitted to Jownal of Ground Water, In press.

Freeze, R.A. and J.A. Cherry, 1979. Groundwater, Prentice-Hall, New York.

Kueper, B.H. and J.I. Gerhard, 1995. Variability of point infiltration rates for two-phase flow in heterogeneous porous media, Water Resources Resemch, 3 1(12), 297 1 - 2980.

Kueper, B.H. and D.B. McWhorter, 1991. The behavior of dense, nonaqueous phase liquids in hctured clay and rock, Ground Water, 29(5), 716-728.

Loney, J.E., D.A. Edwards, and J.W. Little, 1996. Groundwater capture and remediation with engineered blast-bedrock zones, Northeastern Geology and Environmental Sciences, 18(3), 195-200.

Mackay, D.M. and J.A. Cherry, 1989. Groundwater contamination: Pump-and-treat remediation, Environmental Science and Technology, 23(6), 630-636.

Pankow, J.F. and J.A. Cherry, 1996. "Dense chlorinated solvents and other DNAPLs in groundwater". Waterloo Press, Oregon, U.S.A.

Poulsen, M. and B.H. Kueper, 1992. A field experiment to study the behavior of tetrachloroethylene in unsahirated porous media, Environmental Science and Techno logy, 26(5), 889-895.

Reitsma, S. and B.H. Kueper, 1994. Laboratory measurement of capillary pressure- saturation relationships in a rock fracture, Water Resources Research, 30(4), 865- 878.

U. S. Environmental Protection Agency, NutionaZ Priority List 1 995, Agency for Toxic Substances and Disease Registry.

2.1 Fractured Rock Models and Single Phase Flow

Fractures in rock masses occur as a resdt of a loss of resistance to d.erential stresses

and a subsequent release in stored elastic energy (Bates and Jackson, 1984). Release of

overburden stresses, orogenic activity, including folding, faulting and thnisting processes.

c m create the differential stresses able to generate fractured units. It is rare for a

geological medium to be homogeneous in composition and therefore, release of stress

rarely produces straight fissures with two parallel sides. Along the trace of a fi-acture

exposure, a range of apertures are apparent (see Figure 2.1).

Initial studies addressing flow behaviour through hctures were conducted with rather

crude approximations of fiactures. Laboratory studies of pardlel plate fiacture models

have been conducted using smooth or etched glass (Schwille, 1988; Fourar et ai., 1993)

with fixed separation distances and no contact points in the hcture plane. Under these

conditions and assuming one-dimensional laminar flow, the flux tbrough two pardlel

plates is often assurned to be proportional to the cube of the separation distance, or

aperture. The "cubic law" can be derived as a speciai case of the Navier-Stokes equation

for incompressible, Newtonian, isothermal fluid flow, between smooth, parallel plates.

This momenturn balance equation for flow of viscous fluids may be simplified to

generate a fom of the empirïcal Darcy's law relationship. Fluid velocities must be low to

derive Darcy's law f?om the Navier-Stokes equation shce the inertial forces are assumed

to be negligible with respect to viscous forces. In addition to these restrictions,

integration of flow volume, velocity and driving force over a representative elementary

volume (REW must be perfonned to obtain a macroscopic average fiom the Navier-

Stokes relation (Marsily, 1986). The cubic law is defined as (Bear et al., 1993):

where Q is the fluid flow rate through the hcture, p is the density of the fluid, g is the

gravitational acceleration, w, is the effective width of the cross-sectional expression of

fractures, e is the hcture aperture, Vh is the hydraulic gradient applied across the

hcture and p is the dynamic viscosity of the fluid.

I

Figure 2.1 - Rough-walled frscture trace.

Fourar et al. (1993) created a hcture model by using glas plates, smooth and roughened

by using glas beads glued on them. Four situations were examined: smooth plates with a

1 mm separaiion distance, rough plates at two different separation distances and one

instance where the rough plates had contact. Two-phase flow of air and water in these

artificial horizontal hctures were examined. Three anaiytical approaches were

presented: Darcy's law empiricai relationship; two-phase pipe flow; and two-phases

likened to the behaviour of one homogeneous phase. With the Darcy approach, the lack

of relative penneability data for hctured media was pointed out and the use of phase

saturation was substituted. Using phase saturations, the relative permeabiiities of each

phase would sum to unity. Fourar et al. (1993) present Iaboratory observations of

imrniscible phases in rough hctures which interfere with one another and result in much

Iower spaces in the hcture available to each fluid Relative pemeability curves fiom the

porous media literature were used as an approximation of the interactions in a fracture

plane. Deviations from Darcy's law were observed for the rough hcture condition and

attnbuted to inertiai forces.

The second analytical approach adopted by Fourar et al. (1993) deds with two-phase

fluid flow through pipes fiom tmditiooal fluid mechanics literature. Separate equations

for each fluid phase, as in the Darcy model, are utilized. However, in contrast to the

Darcy's Iaw approach, inertid forces are considered in the pipe flow approach. Flow

pattern and interaction of flow stmctues were photographed and found to be similar to

those contained in pipe flow literature. Inclusion of inertiai forces in the pipe flow model

also included a parameter which adjusts pressure gradients as relative permeabilities

would be in Darcy calculations. The combined behaviour of the two phases were

considered in the third analytical method. Here, the Reynolds number was calculated

from a hydraulic diameter for the hcture and the fluid properties. This method was

found to be predictive for a greater range of pressure gradients, used here because of the

gas-liquid phases, than the standard pipe flow model. Of particular signincance was the

observance of transient flow paths which were non-repeating in the smooth and 'rough'

hctures. The artificial nature of these particular fkcture models may explain the

observed lack of channeling which other researchers have welldocumented in natural

rock hcture openings.

Iwai (1976) described studies where one-phase flow through open hcture conduits were

measured. The objectives of Iwai's thesis were to examine the validity of 'cubic law'

approximations for both ideal and redistic rough hctures as well as to determine the

effects of contact points in the hcture plane. Iwai (1976) conducted experiments with

polished and 'mated' granite cores to simulate smooth-walled parallel fractures; granite,

marble and basalt 'naniral' fÏactures were tested in a radial flow apparatus under cyclic

normal loading. When defining a hcture aperture for the systems tested, a no-flow or

maximum normal stress condition was sought. The author found that under maximum

normal stress, the fiachire sample produced a small amount of flow. This non-zero

condition was called residual flow. A relationship between stress and flow rate data was

presented. A cubic relationship, with a modifjhg term to account for residual flow, was

found to be a reasonably good description when Reynolds nurnbers were below 100, the

contact area is regular, and the hcture aperture distribution was relatively uniform (Iwai,

1976).

Witherspoon et al. (1 979) present data nom the PbD. work of Iwai (1 976) in a journal

paper. Three induced single rock fractures in three specimens of marble, granite and

basait are discussed Applied normal loads were varied and the resulting permeability

associated with each were measured. The main objective of the research was to examine

any size effects that may influence fluid flow tbrough rock fkcture samples tested.

Essentidly, this was a study of a representative elementary volume concept for rock

fractures. Granite rock cores were hctured in a perpendicular orientation to the long

axis of the core and a normal stress applied during testing. Variations in flow rates were

found to occur for simüar conditions in dinerent sized samples. Calculations of fracture

aperture were made using a cubic relationship for fiacture hydraulic conductivity in a

Darcy's law equation. The results of this study suggea that extracted field cores for

laboratory tests will exhibit lower hydraulic conductivities if below a minimum stated

surface area for radial flow.

Witherspoon et al. (1980) used the sarne hcture materials to investigate the validity of

the cubic law. The authors present a table for flow regirne classification in fkactures

based on relative roughness and Reynolds nurnber. Transition to turbulent flow at

Reynolds numbers nom 2300 to 2400 were observed by various researchers. However,

no definition is provided of a non-laminar region between laminar and turbulent flow

where inertial forces have become significant but turbulence has not yet been reached.

These fractures were created and then tested at different normal stresses afier being fully

separated. Surface mating &er release of confining pressures is not expected to mirnic

field situations or to provide accurate fracture distribution data. The authors conciude

that in their investigation of radial and linear flow through basalt, marble and granite,

permeability can be uniquely determined by fracture aperture and that the cubic

relationship holds. Some adjustment for hcture roughness rvas deemed necessary.

Marsily (1986) outlines the 80w regimes for which flow is laminar, non-laminar and

turbulent. Flow types are based on relative roughness, q :

where E is the mean height of asperities of a hcture surface and DH is the hydraulic

diameter of the hcture. The Reynolds number, %, is plotted with the relative roughness

term to define a flow regime. The Reynolds number, defined for a fracture, is given by

(Marsily, 1986):

where 6, is a characteristic length term, for a fiactured system this is taken as the hcture

separation distance and q is the specific discharge or Darcy flux.

Gale (1990) examines the literature dealing with the analysis of physical hcture studies

cornpared with laboratory examinations of h c t u r e flow. Fracture pemeability is

discussed at length as weil as on flow regime definition. Gaie presents the evolution of

research departing fiom a parallel plate assumption for fractures where attempts were

made to quanti@ the eeects of contact points and roughness. Note that for smooth

laminar flow, the hcture hydraulic conductivity is given by (Bear et al., 1993):

where K is the hydraulic conductivity of the fiacture. The following relationship was

proposed by Lomize for hcture hydraulic conductivity (Gaie, 1990):

where 2b refers to the hcture separation distance, and the ratio of maximum asperity

height is given by a,,,,. The fiachire hydraulic conductivity provided by Louis for rough,

laminar flow conditions is (Gale, 1990):

This expression uses the average aspenty height, G, divided by the hydraulic diameter,

DH (dehed as double the fracture aperture). With fracture walls in contact, these

particular ratios give slightiy different perrneabilities. It is important to note the lack of

data and reliable analyses presentiy available for real rock fkcture characteristics. The

absence of an aperture characterization technique for linking observed flow properties is

pointed out.

Gale (1 987) injected

exarnined the aperture

resin into single fractures under varying normal stresses and

distributions denved. The sampie was allowed to be tested under

its own weight, which would have resulted in a stress release in the fracture and,

subsequently, a wider hcture . Gale's assumptions made for calculating residual aperture

under maximum stress conditions using the cubic law relationship may therefore be

invalid.

In another artificial fiacture mode1 study, Hakami and Barton (1990) created transparent

fracture epoxy replicas fkom drill cores obtained at the Stripa mine in Sweden and fiom

roadcut samples. Aperture measurements and flow characteristics were measured and

presented with a discussion of roughness, hcture closure under stress, and tortuosity. A

unique method of measuring fiacture aperture, in which water volumes on the order of

tens of microliters were injected into the hcture and the surface area occupied by the

fluid was measured, was used to obtain a lognomal hcture aperture distribution. Snow

(1970) conducted a field study where field packer test results were related to fracture

aperture distributions and a lognormal aperture distribution was found. The study by

Hakami and Barton (1990) concluded that well-mated hctures have smaller aperture

ranges and therefore conduct fluid more evedy (Le., tortuosity is less of a factor). This is

an important observation relevant to studies in undisturbed natural rock fractures.

Another notable conclusion made fiom this study is the consistently higher physical

aperture measured compared with the caiculated hydraulic aperture.

Tsang and Witherspoon (1983) investigate hcture roughness profiles in relation to

normal stresses and fluid flow through fractures. Surface profiles are presented fiom a

previous profiling study and are matched at varying amounts of offset. A correlation

relates f l id flow and degree of closure as a function of the fracture roughness. This

relation is dependent on hypothetical hcture cross-sections using mirmred data fiom

only one side of a real fissure. Based on this, large scale undulations in hcture surface

roughness are judged to be significant influences on fluid flow; it is suggested that these

roughness wavelengths, on the order of several centimeters, be considered when selecting

fracture sample sizes in the Iaboratory. These conclusions are based on their earlier work

(Tsang and Witherspoon, 1 98 1) which presented a relation between effective Young's

modulus and a hcture-roughness profile. This work studied the effect of normal stress

on flow and concluded that under high stresses, parailel plate approximations of a fiachire

plane are not adequate for predicting flows. The authoa also determined that the

percentage of surface area in contact, at significant normal stresses, is quite low.

Experimental work on rock cores were fiom the work of Iwai (1976) which opened up the

fkctures completely before applying high levels of stress.

The limitations of the approach taken by Tsang and Witherspoon (1983) are that: the

measured profiles are measured in only two dimensions; flow is assumed to travel dong a

constant aperture channel in the t k d dimension; and only one side of a fracture is

profiled. Laboratory observations of rock fractures suggest that fracture planes are

variable in three dimensions, so constraint of the fracture length characteristics are not

accurate. Single side characterization, through profiling or casting, neglects matrix

islands in the bcture planes and the effects of minerai solution on the opening.

Gentier et al. (1989) developed a digital imaging method for the physicai study of

fiacture voids. The ability to collect this information accurately will ultimateiy aid in

better understanding the mechanical and hydraulic behaviour of rock fiachires

Deficiencies in other methods used to obtain this surface characterization are pointed out.

They suggest that proniuig techniques and low boiling point metal injection into fractures

have serious limitations in their realistic application due to the difficulty of matching

profilorneter traces and in metal adhering to hcture surfaces, giving inaccurate cross

sections and inaccurate detemination of void space. Billaux and Gentier (1990) use a

resin injection technique for the study of a natural rock hcîure to obtain casts at three

different normal stresses. Preferential flow paths are cietermined fiom image analysis of

the void thickness and simulations are matched to actual flow tests conducted on a

hctured sample. The authors find a good correlation between projected and actual flow

rates.

Tsang (1984) uses an electrical mode1 as an analogy to fluid flow through a single

hcture and discusses tortuosity and roughness effects. This study concludes that

roughness and tomiosity are both major factors in flow, especially when contact areas

exceed 30% of the hcture plane surface are& A Gaussian distribution was used for

modelling the fracture distribution and a two order of magnitude of difference in flow rate

was attributed to the effects of tortuosity not included in the cubic law relationship. The

electrical analog models simulate flow reiated by the ideal cubic law relationship.

Raven and Gale (1985) attempted to understand the effect of a stress field on the

penneability of a hctured unit. Changes in fracture aperture as a result of nomal stress

application and the corwsponding change in flow rate through that fracture were studied.

Several rock core samples were tested, each originating fiom the same hcture which was

90 degrees to the long axis of the core. The core sizes dinered and were subjected to

cyclic loading. Raven and Gale found that normal load application on a hcture plme

reduced overall flow rates, increased tortuosity, decreased deformation hysteresis

between loading cycles, and caused an increased deviation fiom cubic law predictions.

Tsang and Tsang (1987) discussed the appropriateness of using a channel model to

predict flow through natural rock hctures. Four parameters were deemed necessary to

characterize the channel properties. These included the aperture density distribution, the

spatial correlation length, and the effective channel length and width. Based on granite

core profiling traces presented, a gamma distribution was used to describe the aperture

distribution in this channel model. The authors caution that relating the concept of

tortuous flow c h a ~ e l s , which carry the majority of flow, to standard fracture

characterization techniques that use fracture length, spacing, orientation, and aperture

may be difficult. Each channel was generated with the same statisticai aperture

distribution. A correlation length of 0.2 times the channel length was chosen based on

the profile data. This preliminary numerical modelhg exercise showed promise but had

not been properly validated.

Tsang et al. (1988) M e r the charnel model presented in Tsang and Tsang (1987).

Aperture distributions and spatial correlation lengths for the length of a flow channel

were examined dong with consideration of channel residence t h e , channel volume, and

flow rate. This method relied on statistical homogeneity in a hctured system as well as

a somewhat limited unit permeability (where a REV approach could be wd). In

addition, this method is not detemiinistic. Tsang and Tsang (1989) modelled fluid flow

through a generated variable fracture using a lognormal aperture density distribution

based on the field and laboratory work by Gaie (1987). Note the change fiom the initial

gamma distribution to a lognomal distribution by the authors. Unfominately, discussion

of this change in distribution is not provided. Flow simulations were conducted through

the system and showed a confluence of flow at wider apertures where the bulk of flow

was transported.

Moreno et al. (1988) modelled flow and solute rnovement through a rough-walled

fracture plane, using the concept of flow channeling rather than a parallel plate

approximation. The investigation was undertaken to determine the controlling factors in

these conduits dong the fiacnire plane. The authors, citing field and laboratory

experiment results, stated that spatial correlation lengths c m be on the order of magnitude

of the measurement length in a particular study. Channeling was amibuted to these

correlation lengths and afEected the fracture aperture distribution.

Moreno et al. (1990) indicated that tracer injection and flow test results through

statistically generated fractures depended on the injection location and the flow rate

applied. This study followed fiom Moreno et al. (1988) which dealt with preferred paths

in a generated two-dimensional hcture plane.

Brown (1987) created fracture models using hctal topography and then related flow to

surface roughness. He utilized Reynolds law which c m be derived from Navier-Stokes to

account for non-planar, non-parallel rough surfaces. With reference to Tsang (1 984), he

explained the ciifference in predicted and observed flux through a fracture due to

tomiosity. The author pointed out that the randorn resistor values used were not

correlated in space and that this wodd have greatly affect how 'flow' proceeded through

the 'network'. Brown (1987) discussed dinerent qualities of fhcture roughness in tems

of amplitude and fkequency of aspenties and found that deviation nom the cubic law was

greatest at lower mechanicd separation distances. Corrections to the cubic law,

suggested by other authors, were presented and compared to examine the relative

effectiveness of each. An arithmetic average of mechanical aperture was suggested to be

the best parameter used in this relationship, though the range of aperture values obtained

low flow rates within a factor of two fiom the input conditions.

Neuzil and Tracy (1981) reanalyze the experimental data from flow tests in fractures

under compression and extension (Iwai, 1976). Laminar fluid fiow between two paralle1

plates (Poiseuille flow) was discussed and a modified version was suggested for data

anaiysis. A lognomal aperture distribution was codimed for these data. Because large

apertures in a fhcture plane control flow in channels, the authors stress the importance of

tailing on distribution fûnctions. Therefore, tnincation of aperture distributions would

have a great impact on modelled flow rates.

Long et al. (1982) discussed the use of equivalent porous media concepts for networks of

discontinuous hctures. The analysis they presented of various fracture network

realizations supported the view that uniform aperture distributions, high fracture

densities, and nonuniform fÎacture orientations can probably be reasonably simulated by

using an equivalent porous media approximation.

The validity of equivalent porous media, or continuum, approaches to groundwater flow

calculations were assessed by Berkowitz et al. (1988) using a mathematical and

numerical model. Cornparison to existing analytical models were made in an attempt to

validate the model used A continuum approach was deemed appropriate to predict tracer

movement and breakthrough in this homogeneous, isotropie hctured formation. This is

clearly a special case where the geometry is regular and continuous; the use of this

approximation for field situations is suggested when the equivalent porosity and

equivalent dispersivity is known.

Schrauf and Evans' (1986) Iab study discussed the validity of the cubic law and presented

findings in relation to Raven and Gale (1985) and Gale (1982) where deviations were

noted. A parailel plate model was found to be inadequate and red ted in lower apertures

than those obtained by measuring average ficichue apertures. Hydraulically detexmined

apertures were found to be less than the actual average aperture. Schrauf and Evans

applied the hydrauiic conductivity reduction factor by Louis (presented in Equation 2.6

above) and found it to accurately adjust the aperture detenninations. Flow rate was

determined to be invenely proportional to the fourth power of the aperture. Experimental

data was measured in both linear and non-lhear flow regimes and was matched to the

model relationship.

2.2 Fracture network models

Long et al. (1982) proposed a normal distribution for the generation of hcture

orientations in a numencal model. Nordqvist et al. (1992) utilized a Fisher distribution,

which is nonuniform and isotropic while Bear et al. (1993) discussed hc ture network

generation by various authors. Uniform, Bingham and Gaussian distributions have also

been used for orientation of flow planes in a finite volume. Bear et al. (1993) discussed a

three-dimensional box model which consisted of statistically generated finite circular

disks. The disk centres follow a spatial density distribution and the disk position, radius

and orientation are positioned according to different density distributions. In Dverstorp

(1 99 l) , flow channels within the disks were assumed to cany flow and were modelled to

behave as either rectangular channels or circular tubes.

Cacas et al. (1990) modelled and attempted to predict flow and transport using a discrete

fhcture network model (rather than a continuous equivalent model). Use of the

Andersson and Dverstorp disks having certain orientation, spatial position and trace

lengths were used. Hydraulic conductivity was plotted as a fiinction of the distance from

the flow test; this was treated similarly to analyses assessing the use of equivalent porous

medium models. Calibration, which used both g e o m e ~ c data for the hc ture network

and measured hydraulic conductivities from borehole testing, were used to then predict

tracer test results and general hydraulic behaviour for mode1 validation.

Clemo and Smith (1997) used a hierarchical approach to modelling solute transport in

fhcture networks. Primary flow paths were assigned and quantified and conmbuting

fractures were lumped into network blocks with associated conductivities.

23 Two-phase fïow in fractures

Schwille (1988) used parallel plate models to midy flow in fkactured systems; these

consisted of two parallel glass plates and two fiosted g l a s plates. Two-phase flow

experiments of dense chlorinated solvents and water were conducted at different plate

separation distances. In this hornogeneous system, fingering of the denser fluid was

observed rather than a srnooth fluid fiont. Use of the term fingering, however, can only

be properly used when such a system is perfectly homogeneous, as in this case of uniform

plates without contact points in the hcture plane. In typical hcture distributions, as in

Figure 2.1, a dense non-wetting fluid will preferentiaily enter larger apertures due to

lower entry pressures rather than face viscous or density instabilities.

Pruess and Tsang (1990) modelled wetting and non wetting phase relative permeabilities

for "real" rough walled fractures using lognormal aperture distributions. The fracture

length was idealized as behaving as a parallel plate opening locally, but having an overall

deflned distribution. This mode1 neglected the hysteresis typical of two-phase capillary

pressure-saturation relationships because aperture availiability to the fluid is not

discussed.

Karasaki et al. (1994) utilized a mode1 to generate capillary pressure and relative

permeability curves for a two-dimensional fracture network. A uniform distribution was

used to generate the fiachue length, orientation, apertures and location. Relative

penneabiliv was suggesîed to be signincantly lower than intrinsic permeability due to

trapped phases of air or water in the unsaturated zone.

Horie et al. (1990) used cmde fhcture represenfations of stacked rock blocks which have

been sawed and fitted into a laboratory colurnn. The purpose of the study was to examine

capillary effects fiom one biock to another (across the artificial fracture). This particular

feature was quantified in an effort to determine if dual porosity models should include

continuou capillary considerations. A recommendation was made for the inclusion of

capillary continuity in models where matrix porosity is considerd in a hctured medium.

G l a s (1993) considers gravity, aperture geometry, and wettability when modelling

'fingering' of w e t h g fluid into fractures. A modified percolation theory was used to

facilitate the imbibition of fluid into varying aperture separations and accounted for

interfacial cwa twes which other percolation models lack. Note that 'fingering' used

here is better descnbed as channeling because fingering is a characteristic of uniform

plate separation (Schwille, 1988), or of homogeneous porous media.

Reitsma and Kueper (1994) performed a laboratory investigation of capillary pressure and

saturation relationships in a n a d rough-wdled rock hcture. Drainage and imbibition

c w e s for this fracture were fitted to a Brooks Corey function defined for an equivalent

porous media. Testing was performed while a nomal load was rnaintained on the

fiacture. The hcture aperture distributions were inferreci at each normal load through

analysis of the capillary pressure-saturation data.

Kueper et al. (1992) modelled the scenario involving h e d and unlined waste disposai

ponds in hctured media Site data was presented f?om a contaminated area where this

activity had occurred. Fracture spacing, non-wetting phase density and aperture

sensitivities relative to f lues were presented. The authos employed a Brooks Corey

capillary pressure relationship, consistent with that later observed by Reitsma and Kueper

(1994). The conditions for DNAPL entry into water satwated hctures are given in ternis

of interfaciai tension, pool height, hcture aperture and wetting angle.

Kueper and McWhorter (1991) performed numerical simulations for the migration of

DNAPL into a water sanirated rough hcture. The time required for a DNAPL to

penetrate a fkactured clay aquitard was found to be inversely proportional ro the fiacture

aperture, the height of DNAPL pool above the formation, and the dip of the fracture frorn

horizontal. Further analysis predicted that upward hydradic gradients will inhibit

downward DNAPL flow, and downward gradients will increase downward DNAPL flow.

Laboratory experiments by Chown et al. (1997) later confirmed that upward hydraulic

gradients irnpeded downward DNAPL fiow through a single rough-walled hctwe. Two

separate rough-walled rock fractures were examined and tested, each having different

aperture characteristics. The work undeaaken in this research follows the work of

Chown et al. (1997) in order to examine the impact of cross-cutting, multiple hctures on

two-phase flow.

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Raven, K.G. and J.E. Gale, 1 985. Water flow in a naîurai rock hcture as a h c t i o n of stress and sample size, Intemtional Journal of Rock Mechanics, Mineru1 Science und Geomechanical Abstracts, 22(4), 25 1 -26 1.

Reitsma, S. and B.H. Kueper, 1994. Laboratory meanirement of capillary pressure- saturation relationships in a rock hcture, Wuter Resources Research, 30(4), 865- 878.

Schwille, F., iranslated by J.F. Pankow, 1988. Deme Chlorninted Solvents in Porour and Fractured Media: Model Eqeriments, Lewis, Chelsea, Michigan.

Schrauf, T.W. and D.D. Evans, 1986. Laboratory studies of gas flow through a single natural fkict'ùre, Water Resources Research, 22(7), 1 O3 8- 1050.

Snow, D.T., 1970. The fiequency and apertures of fractures in rock, International JO urnai of Rock Mechanics and Mineral Sciences, 7,23 -40.

Tsang, Y.W., 1984. The effect of tortuosity on fluid flow through a single kachire, Water Resources R e s e d , 20(9), 120% 12 15.

Tsmg, Y.W. and C.F. Tsang, 1987. Channel model of flow through fkactured media, Water Resources Research, 23(3), 467-479.

Tsang, Y.W. and C.F. Tsang, 1989. Flow channehg in a single fiacture as a huo- dimensional strongly hetergeneous permeable medium, Water Resources Research, 25(9), 2076-2080.

Tsang, Y.W., C.F. Tsang, 1. Neretnieks and L. Moreno, 1988. Flow and tracer transport in hctured media: A variable aperture channel model and its properties, Water Resources Research, 24(1 S), 2M9-2060.

Tsang, Y.W. and P.A. Witherspoon, 198 1. Hydromechanical behavior of a deformable rock hccnire subj ect to normal stress, Journal of Geophysical Research, 86(B 1 O), 9287-9298.

Tsang, Y.W. and P.A. Witherspoon, 1983. Correlations between hcture roughness characteristics and fractue mechanical and Buid flow properties, Issues in Rock Mechanics, 560-567.

Witherspoon, P.A., C.H. Amick, J.E. Gale, and K. Iwai, 1979. Observations of a potential size effect in experimental detemünation of the hydraulic properties of fkctures, Water Resources Research, 15(5), 1 142- 1 146.

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MANUSCRIPT

Laboratory experirnents were performed in which upward hydrauiic gradients were

applied across a rock hc t i ne network to arrest the downward flow of dense non-aqueous

phase liquid (DNAPL). Tetrachloroethylene (PCE) was pooled above a hctured

limestone block at varying heights, while a hydradic gradient was applied across the

sample. The effect of PCE pool height on the arresting gradient was examined as well as

the effect of decreasing interfacial tension between the fluids. PCE was pooled above the

hcture both with and without a porous medium present to simulate an aquiferhedrock

scenario, and a lagoon scenario, respectively. For a given pool height, the corresponding

arresting gradients for drainage runs were smaller than the gradients necessary to hait

flow during wetting runs. Drainage and wetting pairs displayed a hysteretic relationship

consistent with hdings flom previous studies for a single hcture.

For larger pool heights, PCE was able to enter into the fiachire network against higher

upward gradients. Cornparison of nins both with and without a porous medium present

above the rock sample showed that maximum PCE flow rates and arresting gradients

were greater for the case of a porous medium present. When the interfacial tension

between fiuid phases was decreased in the porous medium runs, the maximum PCE flow

rates and the arresting upward hydraulic gradients increased under similar pool heights.

Competing effects of multiple hctures do not appear to facilitate downward migration of

PCE concurrent with upward water flow.

Constmcting physical models to understand and predict the migration of multiple fluids

through frachired media is a continuing challenge for contaminant hydrogeologists and

petroleum engineers. Beyond oil indusûy applications of two-phase flow, recent interest

in the characterization of these systems has been fuelled by proposais for high-level

radioactive waste burial in hchifed formations. The presence of dense non-aqueous

phase liquids (DNAPLs), such as chlorinated solvents, PCB oils, and coal tars, in many

aquifers in the industrialized world has aiso become an increasing public health concem

(Pankow and Cherry, 1996). The discovery of non-aqueous phase liquid (NAPL) in

hctured formations has catalysed the research of two-phase flow behaviour in hctures,

refer to Figure 1.2. The complexity of hcture geometry and definition hm prevented

any success in remediating these units to date. Sorption to ma& walls, matriw porosity

effects, and dead-end fractures are significant complications in addition to the lack of data

available to quantitatively describe natural fracture networks.

Experimental work with single fractures in the form of mode1 constructions, hcture

castings or actual rock and clay specimens have been performed extensively. Various

approximations for flow behaviour in single hctures have been made with etched,

smooth and rough glass models (Schwille, 1988; Fourar et al., 1993). Descriptions of

variable aperture fracture planes have been put forth by researchers using hcture casting

methods (Hakami and Barton, 1990; Billaux and Gentier? 1990; Gale, 1987) and

profilorneter and mercury porosimetry studies (Myer et al., 1993). Tsang and Tsang

(1987) fit a gamma function to experimental aperture distribution data, while other

researchers have obtained fits with lognormal distributions (Snow, 1 970; Gale, 1 987;

Hakami and Barton, 1990). More recently, Reitsma and Kueper (1 994) and Chown et al.

(1 997) have performed two-phase flow laboratory testing with rough-walled, single rock

fractures.

Billaux and Gentier (1990) impregnated fractures by resin injection methods and later

digitized the casts produced to determine the contact points and open flow areas in a

£facture plane. Effective apertures were sought based on the observed mechanicd and

hydraulic data collected for different rock types. Producing a reliable correlation between

physical and behavioural properties wouid aid in accurate flow determinations. Effective

hydraulic apertures are usually calculated fiom flow rates produced through the specimen

and backed out of the cubic law relationship. Numerical models often use the cubic law

relationship at the local scale at nodes dong the hcture plane. Mass flux aperture

calcufations can be made, based on tracer test data, and these aperture approximations

tend to overstate the tme value while effective hydraulic apertures will underestimate the

achial mechanical separation distance. iwai (1976), Gale (1987), and Tsang and Tsang

(1988) suggested a channel fiow mode1 in the plane of the hc ture where there are areas

of no-flow and areas where most of the flow occw. Channels were expected to Vary in

separation distance dong their tortuous length.

Kueper and Mc Whorter ( 199 1 ) numerically simulated the slowing of downward DNAPL

migration by upward hydraulic gradients across a single, initially water-saturated

hctured aquitard. In their numencal model, porous media features were incorporated

and assumed to be equivalent to mechanisms occunïng in rough-walled fractures.

Relative permeability relationships, capillary pressure functions and e n m pressures were

assurned to be analagous to porous media behaviour. This approach was justified by

recognizing the analogy between the spatidy variable distribution of local apertures in a

rough-walled fracture plane, and the spatially variable distribution of pores and pore

throats in a porous medium. Chown et al. (1997) designed and consmicted an upward

hydraulic gradient flow ceIl to examine this scenario at the laboratory scale and provided

data that agreed with the trends determined in the numencal study. The work of Chown

et al. (1997) demonstrated that upward water flow can arrest the downward migration of

DNAPL in single rock fractures.

The primary objective of this study is to extend the work of Chown et al. (1997) to

detennine if upward water flow can arrest the downward migration of DNAPL through a

hc ture network. A second objective of this study is to investigate the ability of upward

hydraulic flow to arrest downward DNAPL migration when the interfacial tension

between the phases has decreased. The practical application of applying upward

hydrauiic gradients at a field site is that a "hydraulic bottom" may be created beneath a

DNAPL source zone, allowing implementation of aggressive remediation technologies

without the risk of vertical DNAPL rnobilization.

3.3 Materials and hfethods

Single, rough-walled hctures have been successfûlly induced along existing weakness

planes in limestone blocks using a uni-axial compression device (Reitsma and Kueper.

1994; Chown et al., 1997). This method was extended to create a multiple hcture

specimen whereby each fracture maintained its integrity throughout the inducement

process. Reitsma (1992) suggests that total separation of fiacture walls, as well as

destressing the block containing a hcture, wiil result in irrevenible alteration of the

initial void geometry. This alteration includes losing material in the hc ture plane, and

changing the aperture distribution and fiow paths within the hcture. Extrachg a rock

specimen which contained an intact open hc ture network, without destressing the

sarnple during extraction, was deemed to be unfeasible. It was dso recognized that

evaluation of the ability of upward hydraulic gradients to arrest downward DNAPL flow

did not require an undisturbed b c n i r e network fkom the field, but rather a sample

containing well-defined intersecting fi-actures. Competent limestone samples were

obtained from various outcrops and manipulated in the laburatory.

3.3.2 Materials

Several outcroppings of Ordovician limestone were examined in the Kingston, Ontario

area for evidence of weak planar features, such as stylolites, which could be extracted

without disturbance and then subsequently exploited. Stylolites are thin, jagged, teeth-

like planes found in carbonate rock that forrn diagenetically as a result of intense

pressure. Carbonate material is dissolved at grain contact surfaces while the formation

undergoes high normal stresses, leavùig behind insoluble material such as various clay

minerais.

Several samples were obtained fiom a thickly bedded limestone deposit close to the shore

of Lake Ontario, West of Kingston. These muddy carbonates belong to the Lowville

Formation in the Black River Group. Rock situated at the top of roadcuts which had

undergone some degree of congelihction, or fiost wedging, were most readily extracted.

The samples which were obtained measured at least 300 mm in each dimension, allowing

for M e r cutting after the network was induced.

The matrix of the obtained rock samples was dense, hornogeneous and fine-grained to

massive in texture with calcium carbonate inclusions resernbling pisoliths. Various

fossils present in the matnx were discontinuous and, though more porous than the

surrounding matrix, were not expected to add to the matrix porosity to any significant

degree. Measurernents of matrix porosity were performed on these samples and found to

be 0.8% (CORELab, 1997). Secondary porosity was therefore not considered in flow rate

caiculations. Significant contaminant losses to the matrix as a result of aqueous phase

difbion would aiso not occur on the time scale of the performed experiments.

Rough-walled multiple hcture pathways were induced in one of the carbonate samples

in a controlled manner. Shallow grooves, five rnillirnetres in depth, were cut dong the

trace of weakness planes on the top and bottom faces of the sarnple. The specirnen was

balanced on circula rods ninning the length of the groove and placed in a uni-axial

compression machine. This process was repeated for each firicture induced in the sample.

The sample remained under confinement throughout the loading cycles to ensure that the

hctures did not open up, and to prevent splaying of the fkcture block. Figure 3.1 shows

a limestone sample after fiacturing has occurred. Once the entire firacture network was

induced, the sample was cut into the final dimensions 152 mm x 203 mm x 23 1 mm. The

fiacture network pattern was mapped and is presented in Figure 3.2. A thin putty

covering was placed over the open hcture traces on the limestone block faces prior to

the application of Devcon Plastic SteelTM resin. The putty prevented resin uptake into the

ftacture openings. Once cured, the resin was machined to allow connection to inflow and

outflow reservoirs. Further details of this process are found in Muzzin (1995).

Tetrachloroethylene (PCE) was selected for use in these experiments because of its low

solubility in water, its high density relative to that of water, its Iow vapour pressure and

its prevalence at contamhated sites across North America (Mackay and Cherry, 1989).

PCE exists as a clear, colourless liquid and exhibits properties which are consistent with

other chlorinated solvent compounds. While ofien considered completely irnrniscible

with water, PCE does have a low aqueous solubility (200 m a ; Pankow and Cherry,

1996). Dissolved and evaporative Iosses of PCE can be neglected in this study due to the

short tirnescale of these experiments. Table 3.1 lists the relevant physical and chernical

properties of tetrachloroethylene at 20°C. The PCE was obtained fiom Fisher Scientific

and was dyed for visual distinction prior to experimentation by a non-partitioning,

strongly hydrophobie powdered dye (Sudan N, Fisher Scientific) at a concentration of

Figure 3.1 - Limestone sample after fracturing has occurred. The sample was confined with nylon banding to prevent fracture disturbance.

Figure 3.2 - Schematic of fracture I

( s a l e 1:4, dimensions s ietwork, mapped from traces on six outer sides hown in millimetres).

0.1 g/L. The interfacial tension between dyed PCE and water was detennined to be lower

than that of undyed PCE and water; both values are presented in Table 3.1.

Wettability tests were perforrned on various iimestone samples cut fiom the same source

unit as that sample used to perfonn the upward gradient flow experiments. Both a matrix

sample and fracture face were tested. The samples were imrnersed in water followed by

the application of one or more PCE drops onto the exposed hcture surface or matrix

sample. The non-wetting character of PCE with respect to water on the surface of the

samples was apparent by the observation that the DNAPL clearly formed spherical beads

on the surface of the limestone in the presence of water. The samples were observed after

24 hours and it was apparent that the non-wettuig character of the PCE was consistent on

this t h e m e . The hcnire plane tested was part of an induced hcture which was

trimmed off the sample block before the resin was applied. Based on these observations,

it can be concluded that the effects of mineral coatings and compositional variation on the

fracture walls do not alter the wettability of the PCE-water system.

3.3.3 System design

The design of the apparatus used to contain and control flow through the rock fracture

network is an extension of that presented by Chown et al. (1997). Modifications were

made on the original design which included changes to the inlet and outlet ports, an

improved effluent collection system, improved fabrication methods, and scaled-up sizing.

The system consists of an upper and lower reservoir surroundhg the rock sample (see

Figure 3.3). Water enters the lower reservoir from a constant head tank and flows up

through the rock specimen into the upper reservoir to an outlet valve. Measurements for

Table 3.1 - Physical and chernical properties of tetrachloroethylene

1 Chernical formula 1

Vapour pressure (at 20 OC) 14.4 mm EIgb

Vapour density 5.83 (air = 1lb

Liquid density 1620 kg/rnJb

[Diamic viscority

I/ Interfacial tension (undyed PCE and water) 1 0.040 I4/xnd

" CRC Handbook of Chemistry and Physics Fisher Scientific Material Safety Data Sheet Pankow and Cheny, 1996

d Tnplicate averages at 24OC using a platinun ring temiorneter (Kniss USA)

calculating the water flow rate are taken by opening a valve which redirects the overflow

to a graduated cylinder. Tetrachloroethylene entered the system through a valve and inlet

port accessing the upper reservoir above the rock specimen. PCE was able to migrate

down through the rock sample to the lower reservoir where the exit flowrate was

measured. A calibrated scale was affuted to the viewing glass on the bottom reservoir to

allow determination of the rate of PCE which exited the bottom face of the ftacture

network sample. Collection and recyciing of PCE was facilitated by drainage of the

lower reservoir into a NalgeneTM carboy.

The upper reservoir of the flow system was 406 mm in height with an intemal cross

section 152 mm deep x 203 mm wide. The reservoir was c o ~ c t e d of three 13 mm

thick çtainless steel plates, bolted together on 38 mm centres with a fkont g l a s wall. A 6

mm thick 'safety' g l a s plate (wire grid enmeshed giass) was positioned in 6 mm deep

grooves milled in the stainless steel side plates and was fastened in place with Devcon

Plastic S t eeP . The PCE inlet, located 25 mm above the bottom edge of the reservoir.

was constructed of 9.5 mm copper tubing terminated by a brass distribution fitting at the

midpoint of the interior cross section. The nibing and fitting were inclined at 10° fiom

the side of the reservoir and covered with a fine bras screen to prevent water, air or

porous media fiom entering the tetrachloroethylene inlet. A two-way 9.5 mm I.D. bras

valve (Nupro Company) controlled flow into the reservoir fkom the DNAPL tank. Water

overfiow fiom the upper reservoir exited through a 152 mm length of 9.5 mm copper

tubing to a waste carboy or graduated cylinder, controlled by two 9.5 mm I.D. bras

valves (Nupro Company). A Plexigiasm plate measuring 171 mm wide x 229 mm,

connecting a 6 mm I.D. vinyl tube vented to the hime hood, covered the upper reservoir

and was cauiked into place dliling flow tests. A scale was affixed to the g l a s face of the

top reservoir to measure the height of both PCE and porous media from the rock face.

The bottorn reservoir was constructed of three 13 mm thick staialess steel plates and a 6

mm thick "safety" g l a s fÎont. The bottom of the lower reservoir was a 13 mm thick

stainless steel plate which was angled down toward the eont of the apparatus to facilitate

accurate PCE volume measurement. Water entered the bottom reservoir kom a constant

head water tank via a 9.5 mm I.D. brass valve (Nupro Co.) situated 38 mm below the top

edge. A third valve was located 13 mm below the top edge of the reservoir on the

opposite wall to the water inlet; enabling the removal of air bubbles lodged against the

bottom rock face. The lower reservoir was carefully calibrated with a maximum

estimated error for height measurements of less than 10%.

In designing the rock fracture network containment and seal, particular attention was paid

to ensuring unidirectional flow through the sample in a vertical direction. To eliminate

edge effects upon fluid entry and exit, the rock sample was cut to the exact 152 mm x 203

mm interior dimensions of the upper and lower reservoirs. The rock hcture network,

constrahed by nylon banding and metal clamps throughout the h c t u r e inducement

procedure, was encased in Devcon Plastic SteelN on four sides. The rock was flanked by

the upper and lower reservoirs and pressure sealed, through the use of two 71 1 mm

circderence Viton mbber O-rings placed into milled grooves. Threaded rods extended

through L-brackets were affixed to the upper reservoir, lower reservoir and rock sides,

(Figure 3.3) which enabled the top reservoir to be removed without requiring desaturation

of the hcture network.

The constant head water tank was suspended by 1.6 mm aircraft cable and attached to a

winch and pulley system. The elevation of the overfiow poa on the flow ceIl was

transferred to the constant head water tank scale using a surveying level. Reference

gradients were calculated as the height difference between the water overfiow in the

hydrauiic head tank and the ovefflow in the upper flow reservoir, divided by the vertical

hcture sample length. Experiments were nui between gradients of 0.00 and 0.60.

DNAPL entered the flow ceIl fiom a statiomy stainless steel tank having a large surface

area to rninimize source fluctuations. The level of PCE in the tank was monitored

through a sight glass and rnaintained at a single level throughout each m. Water was

pumped into the PCE source d m through 6 mm copper tubing, forcing the PCE out of a

second tube and into the stainless steel tank. Design of the tank in this manner eliminated

the need to pump PCE and greatly reduced the risk of tubing breaches and spills. Vapour

losses were minimized by maintainhg a water head in the tank above the PCE supply.

The rock sample was flushed with deaired water to saturate the hcture network pnor to

introducing PCE. Approximately 5000 pore volumes of deaired tap water were passed

through the sample before testing commenced. Tap water was utilized to muiimize the

amount of minera1 dissolution occurring in the fractures (distilled water would be in

disequilibrium with carbonate rocks). Deaired water was introduced to the botîom

resewoir of the system where it travelled up through the network and upper reservoir.

3.3.4 Testing procedures

The configuration of the fifieen two-phase flow tests which were performed as part of this

study are presented in Table 3.2. Each test run consisted of measwing the flow rate of

PCE and water under either drainage or imbibition conditions. Drainage conditions refer

to an initiaiiy water-saturated fracture, followed by increases in the non-wetting phase

(PCE) saturation. These conditions were established by initially flowing water at an

upward gradient of 0.60 through the hcture network while the PCE pool was intmduced

to the top of the sample, and then decreasing the gradient to 0.00 in 0.05 increments.

Imbibition, or wetting, conditions refer to increases in the wetting phase (water)

saturation. Imbibition nuis began with high non-wening phase flow rates present in the

fracture network at an applied upward hydraulic gradient of 0.00, and corresponded to

high PCE saturation in the fiachires. Wetting nuiç undenvent an incremental increase in

water gradient across the network fiom 0.00 to 0.60 while PCE flowed and was arrested

in the hcture network.

Exact determination of the upward hydraulic gradient across the rock sample was not

possible due to the PCE pool above the hcture which resulted in a discontinuous water

phase. Hydradic gradients stated are those calculated with water only in the system and

should be considered to be 'reference' gradients.

Runs 1 through 9 were completed with PCE pooled above the network at v w g heights

of 35, 60, 85, 100, and 115 mm. For each pool height, a drainage run was completed

fîrst, followed immediately by an imbibition m. The only exceptions to this were the 35

mm pool height where only a drainage run was perfonned, and the 85 mm pool height

where the dramage (Run 2) and wetting (Run 3) nins were not perfomed sequentidly.

The fracture network was aggresively flushed with water between runs 2 and 3.

Table 3.2 - Configuration of erperimental rum. - - - ---

Reference - - PCE Pool Rnn Type Porous Reàuced Height Mediam Interfacial (mm) Present Tension

Run #2 85 drainage no no

Run #3 85 wetthg no no

Run #5 60 wetting no no

Run #6 100 drainage no no

Run #7 wetting

Run #8 115 drainage no no

Run #9 115 wetthg no no

Run #10 85 drainage Yes no

Run #11 85 wetting Yes no

Run #12 85 drainage Yes Yes

Run #13 85 wetting Yes Yes

-- -

Run #15 85 wetîing Yes Yes

Runs 10 through 15 involved the placement of a 1 1 8 mm lem of # 16 silica sand above

the fracture network. This sand has a measured hydraulic conductivity of 3.53 x IO*'

cm% (Chown et al., 1997). Runs 10 and 11 were conducted at an 85 mm pool height with

the PCE pool meanired in the porous medium. To evaluate the ability of upward

hydrauiic gradients to arrest downward DNAPL migration under conditions of reduced

interfacial tension, Runs 12 and 13 involved flooding in an upward orientation using a

2% polyoxyethylene sorbitan ester (Witconol FLO MO SMO-20) solution, and Runs 14

and 15 involved using a cosolvent solution consisting of 2% polyoxyethylene sorbitan

ester and 10% ethanol (by weight). The PCE pool in the porous medium was maintained

at an 85 mm pool height during the four reduced interfacial tension nuis. Soluble losses

of PCE are increased with the addition of the chemical solutions, however, a constant

DNAPL pool height was maintained above the &tue network throughout the

experiments to ensure complete replenishment of any PCE that may have been

solubilized.

3.3.5 Interfacial tension reduction

Runs 10 through 15 were conducted in order to examine the ability of upward hydradic

gradients to arrest downward DNAPL migration under decreasing DNAPL-water

interfacial tension conditions. The interfacial tensions between PCE and the aqueous

phase were successively lowered for the last two pairs of experimental runs in the bcture

network. Polyoxyethylene sorbitan ester (Witconol FLO MO SMO-20, aiso sold aç

Witconol 2722) is a food grade solublizing sudactant. This surfactant was also used in

combination with 100% lab-grade ethanol (Fisher Scientific) to achieve M e r interfaciai

tension reduction. Table 3.3 presents the relevant physical and chernical properties of this

surfactant. The density and viscosity of each of the injected solutions are presented in

Table 3.4. The interfacial tension measurements for each injected solution are presented

in Table 3 S.

Table 3.3 - Physical and chernieal properties of polyoxyethylene sorbitan ester; trade name Witconol FLO MO SMO-20 (Witco Corporation Material Safety Data Sheet, 1997).

. - . - - - - 1 Specifie gravity 1 .O8

1 Solubility in water "soluble at 25 1 1 Critical Micelle Concentration 12 mgnb 1

a Material Safety Data Sheet, 1997 Interpolated fiom water-PCE interfacial tension vs surfactant concentration curve (Figure 3.4).

Table 3.4 - Density and Mscoaity of injected solutions.

Solution . -. . -. -

- - Density - Viscosity (gn) (cP)

Water (at 25 OC) 0.9971' 0.89'

1 2% polyoxyethylene sorbitan ester (at 24OC) 0.9995~ 1.06~

/ 2% polyoxyethylene sorbitan ester / 10% ethanol (at 24°C) 0.9833~ 1 Sd

CRC Handbook of Chemistry and Physics, 1986 d Tnplicate averages fiom laboratory measurements using pycnometee for density

detemllnations and an Ubbeohde capillaxy viscorneter for viscosity measurements.

Table 3.5 - PCE-water interfacial tension of injected solutions at 24OC.

- -

(&E (dyed) & distilled water 0.029 1 -

1 PCE & 2% polyoxyethylene sorbitan ester 0.0075 1 1 PCE & 2% polyoxyethylene sorbitan ester 1 10% ethano1 mix 0.0050 1

Triplicate averages using platinum ring tensiometer after 20-30 minute equilibriwn

The interfacial tensions between the surfactant solutions and PCE were measured for

POE sorbitan ester concentrations fiom O to 20 g/L; interfacial tensions were measured

for the 1 5 POE sorbitan ester/ethanol mix and PCE where the aqueous solutions ranged

from O to 120 gL in concentration. The values for each sdactant or cosolvent solution

and PCE are plotted in Figure 3.4 and Figure 3.5, respectively. The cntical micelle

concentration (CMC) for the surfactant solution was interpolated fiom Figure 3.4.

Interfacial tension is directly related to the entry pressure of an immiscible phase for a

given system. Therefore, a decrease in this fhid property was expected to alter the results

of the 85 mm pool height sand nins. The theoretical arresting gradient relationship

(discussed later in section 3.4.3) dictates that a decrease in entry pressure requires an

increased gradient applied across the fi-acture to halt downward PCE flow.

1

+ Surfactant-air surface tension

. 8

I ; +Surfactant-PCE t i interfaaal ! tension I

4

1 a I

!

O 200 400 600 800 1000

- Surfactant Solution Concentration (mg&)

Figure 3.4 - Interfacial tension and suriace tension versus sudactant concentration.

! , interfaaal tension

O 200 400 600 800 1000 1200

Cosolvent Solution Concentration (mglL)

i + Cosolvent-air j surface tension

Figure 3.5 - InterfaciaI tension and surface tension versus surfactant/ethanol concentration.

3.4 Results and Discussion

3.4.1 Permeability testing

Before tetrachloroethylene was htroduced to the hcture network, a series of hydraulic

tests were completed to determine the hydraulic aperture of the hcture. Preliminary

hydraulic flow tests were also c e e d out to ensure that the hcture network was

completely water saturated and that air bubbles were not present in the sampie.

Progressively larger values for the effective aperture were obtained during initial testing,

suggesting that the water-filled hcture porosity increased as the air bubbles dissolved

into the aqueous phase. A representation for an effective equivalent aperture, based on

the cubic law, which relates flow rate to separation distance (b) through smooth-walled,

parallel plates for a single hcture has been conducted. The following relationship was

used:

where b is the fiachire separation distance, p is the dynamic viscosity, Q is the fluid 80w

rate through the fiacture network, p is the density of water, g is gravitational acceieration,

w . ~ is the effective width of the cross-sectional hcture area available for flow, and Vh is

the hydraulic gradient. These measurements provided an effective equivalent hydraulic

aperture for the hcture network of 265 p, using an effective width of 497 mm. The

effective width was determïned fiom the summed hchirr lengths on the rock sample

face. This rnethod of calculation provides an average aperture measure, and

underestimates the local-scale maximum mechanical fracture separation distance because

it incorporates the no-flow or minimal flow regions in the averaging procedure. There are

corrections to the cubic law, presented by Louis (1969), which reduce the hydraulic

conductivity of a fiacture plane to account for roughness and contact points. While these

are more accurate indicators of aperture size (Scbrauf and Evans, 1986), physical

measurernents of the fkacture aperture distribution and roughness are required.

The Reynolds number for fluid conditions during testing can be calculated using the

following relationship (Marsily, 1 986):

where q is the Darcy flux, 6, represents a characteristic length and is given by the

hydraulic aperture caiculated at the lowest gradient, and R, is the Reynolds nurnber.

Figure 3.5 presents the data for hydraulic aperture versus Reynolds number (data table

provided in Appenh B). Marsily (1986) States that purely laminar flow occurs within

pore structures when the Reynolds number is less than 10. Based on the Reynolds

number range calculated fiom hydraulic test data, these flow tests were conducted in the

laminar flow region.

250 '

0.00 1.00 200 3.00 4.00 5.00

Reynolds number, Re

Figure 3.6 - Effective hydrauiic aperture versas Reynolds number for preliminary hydraulic flow tests.

Aperture estimations were also carried out using data nom the drainage runs where no

porous medium was present above the rock sample. The reference upward gradients

across the hcture block before PCE flow commenced and the gradient at which flow

began were used to establish a range of entry pressure aperture. The capillary pressure

required for a DNAPL to enter into an initially water saturated hcture is given by

(Kueper and McWhorter, 199 1):

where PE is the entry pressure of the hcture, o is the interfacial tension between fluids, 8

is the contact angle (zero for the system employed here) and e is the largest aperture

giving rise to a continuous non-wetting phase in the sample (entry pressure aperture).

When the DNAPL pool above the hctures and the upward water gradient are at a

hydrostatic equilibrium, Equation 3.4 may be applied to describe the entry pressure

aperture of the system. This equation represents a force balance relationship for DNAPL

entry into an initialiy water sahirated fracture, without a porous medium present above the

fiacture and is described by the following for the experimental system ernployed here

(Kueper et al, 1992):

where A is the height of water and B is the height of DNAPL above the hcture, m w and

are pw the non-wetting and wetting phase densities respectively, hw' is the hydrauiic head

at the top of the hcture.

Equation (3.4) was applied at the gradient before and the gradient at which PCE flow

commenced for each drainage experiment The use of this relationship is warranted for

the conditions before PCE flow because neither water nor PCE exited the hcture

network at this point. Since the change in upward hydrauiic gradients is incrementai, a

range of conditions for the hydrostatic case may be obtained. The apertures which were

calculated using the conditions at fint PCE flow were obviously not representing

hydrostatic conditions, but provided a lower boundary for the fkacture opening. Entry

pressure apertures which were determined to be lower than the effective hydraulic

aperture of the fiacture network were not considered, since it is obvious that the effective

hydraulic aperture must be l e s than the entry pressure aperture (the entry pressure

aperture quantifies the largest continuous conduit through the hcture network). The

entry pressure aperture was found to vary between 265 prn and 321 p. An upper and

lower value of entry pressure was calculated using the gradients observed before and at

initial PCE flow for non-sand nuis. Table 3.6 presents the calculated entry pressure

aperture before and at initial PCE flow fiom each of the non-sand drainage m.

Table 3.6 - Caiculated apertures using hydmulic gradients before and at initiai PCE flow for aii runs performed under drainage conditions with no porous medium present.

A single pore volume for the hcture network was estirnated to be approximately 30 to 37

ml using a combined h c m e exposure width of 497 mm, a hcture length of 231 mm

and the above values for aperture. Accounting for the presence of possible dead-end

fractures and contact areas within the hcture planes would be e-emely difficult to

quanti@. The effective width and heights used in the calculations are best available

approximations based on d a c e expressions of the hctures on the sides of the sample

block.

The bulk hydraulic conductivity of the bctured block was derived fiom the slope of the

specific discharge and hydraulic gradient data (Appendix B). These data were linear over

the range of the hydraulic gradients used in these experiments. Linear regression yielded

a value of 1.58 x 104 m/s for the hydraulic conductivity which is consistent with field

observations of hctured rock (Freeze and Cherry, 1979).

3.4.2 PCE pool height variation

Data fiom Runs I through 9 are discussed in this section. Results for typical drainage and

wetting nuis for a specified pool height, in this case a 100 mm PCE pool (Runs 6 and 7),

are shown in Figure 3.7 (data for al1 runs conducted are presented in Appendix C). PCE

volumes were measured with time for each successive hydraulic gradient while the pool

height was maintained at a constant level in the upper reservoir. The arrows on the graph

indicate the change in hydraulic gradient in relation to the cumdative PCE volume.

In Figure 3.7, tirne is plotted on the independent axis and related to the observation of

PCE flow through the bottom of the hcture. OAen, nrst flow occurred at the moment

the hydraulic gradient was decreased, or shortly thereafter. At a 60 mm pool height (Run

4) flow appeared to begin at a gradient of 0.05. After more than two hours of

measurements, a negligible amount of PCE had accumulated in the reservoir. In addition

to the scarcity of PCE, drops emanating fiom the fracture network bonom were sporadic.

In this particular case, zero time was defined at the next measured gradient of 0.025 when

consistent flow began. A similar situation was observed for a pool height of 85 mm

where flow was erratic and of innifncient quantity to measure accurately. Data points

plotted for negative times refer to the elapsed t h e before flow, with arrows indicaihg the

hydraulic gradient changes and their relative occurrence.

, + Wetting (Run #7)

fime (minutes)

Figure 3.7 - Cumulative PCE volume versus time for a 100 mm pool height under drainage and imbibition conditions. Arrows indicate Vh change of 0.05.

Measurement of flow rates at finite hydraulic gradient increments allowed for a range of

hydraulic gradients to be determined surroundhg the penod of fvst flow in a drainage

m. Table 3.7 presents the arresting hydraulic gradients from each of the non-sand

wetting m. Enay pressures for the system, determined by Equation (3.3) and using the

apertures derived fiom Equation (3.4), were found to range between 18 1 Pa and 2 19 Pa.

Note that this calculation assumes a parailel plate separation as a conservative estimate of

separation distance and assumes water to be perfectly wetting on the fÏacture surfaces.

- The observed shapes of the non-wetting phase pathways upon exit at maximum flow

niggest that local treatrnent of entry is better described by a spherical opening. However,

observations of the wening phase exit patterns on the top block face showed relativeiy

even 'ridges' of water dong the fracture traces on the top face at hi& upward gradients.

Higher pressure wetting phase bubbles did, however, exit the hcture and bubbie up

through the pooled PCE. As the gradients decreased, the ndge itself became Iess

apparent and the number of water bubbles exiting this ridge decreased. Remnants of the

ridge structure at the main conduits of flow remained for intermediate stages where the

water pressure remained high at these locations but was less pronounced at other

locations. The hi& pressure ridge of water completely receded at the gradient before

downward PCE flow began; it is reasonable to assume that the PCE had entered some

regions of the fiacture network, but did not have a çufncient capillary pressure to exceed

the entry pressure of the entire fiacture length. An even distribution of PCE exiting the

bottom face was not observed.

Table 3.7 - Arresting hydraulic gradients for wetting runs without sand.

Specific areas on the top and bottom faces of the fkactured block were more prone to flow

than others. Once these exit points were identifie& a numbering and lettering system was

adopted to record observations of the firequency of bubble and drop emanation. Visually,

flow rates at k t u r e junctions appeared higher than at other parts of the fracture traces

for both water emanating nom the top of the rock and PCE exiting fiom the bottom of the

specimen. The junction at the top hcture face produced water at a faster rate thau other

areas. For drainage runs, where wetting phase saturation was graduaily decreased over

the course of the nin, the ridge structure in place across the fracture traces receded fiom

the junction last. While this area had the largest opening and, consequently, the lowest

entry pressure for non-wetting phase, it did not appear to be infiltrated before other areas.

PCE drops released fiom the hcture network bottom were reasonably consistent in size

for a given location on the hcture trace. Some areas on the bottom face were

consistently releasing drops in a narrow size range. In certain cases, non-wetting phase

drops appeared to block other non-wetting phase drops fkom being released at the base of

the fracture. Coalescing of the drops did not always occur readily.

Based on the observed flow patterns for both wetting and non-wetiing phase liquids, a

channel flow mode1 involving irregular and intersecting hcture planes best descnbes the

physical path taken by these fluids. Intersection of IWO or more variable aperture

hctures appear to behave as a single fiacture with an dtered statistical distribution and

larger effective cross-sectional width.

Cornparison of the drainage-wetting pair data can be made by looking at a plot of PCE

flow- rate against the corresponding upward hydraulic gradient. Flow rates were

determined using linear regression of the steady-state regions of the volume-the plots at

each gradient increment (see Appendix D). Figure 3.8 shows the regressed data fiom

runs 1 through 9 at five difTerent pool heights of drainage conditions and four different

PCE pool heights for wetîing conditions. This plot clearly illustrates a hysteretic

relationship between the drainage and wetting nins. Under drainage conditions in a

fracture network, the gradient at which flow staris is lower than the necessary arresting

gradient under wetting conditions. The gradient at nnt flow increases with increasing

pool height and the arresting gradient also increases for a thicker DNAPL pool. Flow of

tetrachloroethylene through the hcture network began at a gradient of 0.025 for the

lowest pool height and at a gradient of 0.15 for the largest height under decreasing water

saturations. When the water saturation was being increased in the network, flow was

halted at gradients ranging fiom 0.10 for a 60 mm pool height to 0.30 for a 1 15 mm pool

height.

Data presented in Figure 3.8 for PCE flow rates at zero upward hydraulic gradients were

not always similar. Separate data sets of cumulative PCE volumes at zero upward flow

were regressed for both the drainage and wetting runs.

Drainage c w e s exhibit similar slope changes for each pool height examined, while the

wetting curves also appear to foilow a pattern of dope change. The range in flow rate at a

given hydraulic gradient seems to increase for larger pool rates on the drainage and

imbibition curves. Fracture roughness is likened to the pore size distributions which

cause the saturation history of both wetting and non-wetting phases to Vary. It should be

noted that the data plotted are for secondary drainage conditions in the hcture network.

-- 35 mm (D) -r-60 mm (O) - * - 6 0 m m o i --+85mm(D) ' - - * - - 8 5 m m o ,

-e- 100 mm (D) -100 mm 0;

O 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Hydraulic gradient

Figure 3.8 - Combined plot of PCE flow rates at eaeh upward hydraulic gradient applied for pool heights of 35, 60, 85, 100, and 115 mm; "D* denotes drainage run, "W" denotes wetting run.

3.4.3 Pooiing in parous media

Six nins were performed with a porous medium layer in place above the rock sample.

The results fkom these experiments are presented and discussed in this section. Test pairs

were initiated with a drainage nui followed by a wetting run with an 85 mm pool height

in #16 silica sand. After conducting these experiments, the network was flooded with

approximately 2000-2700 pore volumes of water until the amount of residual left in the

rock network and sand was at a minimum. This was defined as the point where suction

applied to the network could not draw out any M e r streams of PCE droplets.

Cornparison of the 85 mm sand run in porous media with its companion run emplaced

without porous media present is interesting. For the two nuis performed at similar source

strengths, the non-sand nin exhibits a maximum flow rate of 50 d m i n and requires a

gradient of 0.15 to anest flow. With a sand layer present, the entry gradient is 0.25 and

the mesting gradient is double that of the sandless run at 0.30. Maximum PCE flow rate

for the sand run is about 90 d m i n . The presence of a sand layer allows a connected

phase of water through the PCE pool. Therefore, at a given hydraulic gradient there are

likely greater capillary pressures within the hc tu re plane.

A 2% polyoxyethylene sorbitan ester aqueous solution was utilized in subsequent runs as

the wetting phase in order to lower the interfacial tension between the fluids. Aqueous

gradient kcrements of 0.10 were used in cornparison with 0.05 gradient increments for

sandless nuis. It is important to point out that drops of PCE began at the highest upward

gradients applied during the drainage m. These drops were neither fiequent nor regular,

but were released fiom the Eracture network before fiow began. The presence of these

small, pre-flow drops can be expiained by the presence of the surfactant and its action on

the residual initially present in the hcture. Examining results from the following

cosolvent run where no sporadic drops were observed suggests that the residual NAPL in

the fracture is lacking due to solubilization between nuis #13 and #14. Figure 3.9 shows

the results from nms #IO through #15. These data suggest that a decrease in interfacial

tension will result in higher downward PCE flow rates for a given hydraulic gradient, but

that the arresting upward hydraulic gradients are similar for a given pool height. Flow

initiation was also observed to begin at similar gradients, but the rate of increase in flow

rate is much steeper for lower interfacial tensions. The maximum flow rates rneasured at

low interfacial tensions are highest of aIi sand nios performed. The entry pressure for

these runs was lower due to the direct proportion of interfacial tension to entry pressure

(refer to Equation 3.3). Using the interfacial tension values rneasured between Buids, the

entry pressure for Run 12 was caiculated to be 57 Pa, and for Run 14 was 38 Pa.

Table 3.8 - Arresting gradients for wetting runs in sand.

Calculation of a theoretical arresting gradient for a given system was proposed by Chown

et al. (1997):

where Ah/& is the arresting gradient, pw is the wetting phase density, Ap is the

difference between non-wetting phase density (m) and wetting phase density, AL is the

length of the hcture, g is the gravitational constant, P,(O) is the capillary pressure at the

top of the fiacture, and PE is the entty pressure at the top of the fkacture. Using this

relationship, the range of theoretical anesthg gradient. for the hcture network with PCE

and water are between 0.87 and 0.88. The arresting gradients calculated for two fluids

with an interfacial tension of 0.005 N/m yields a theoretical gradient of 0.95.

The nui completed with an interfacial tension of 0.005 Nlm between fluids yielded the

largest flow rates of PCE than any other nui performed on the hcture network. This

particular run began with an almost completed water sahuated hcture with M e PCE

residual present, due to solubilization of PCE caused by the 2% Witconol solution sitting

in the hcture between rus . A signifiant dserence between the 2% surfactant nin and

the cosolvent run is the large PCE drop size observed during the cosolvent m.

The PCE flow rates measured for the sand nins performed under wetting conditions were

higher than those measured during the drainage anaiogs. However, this is inconsistent

with the results observed by Chown (1 994), where flow rates were higher for the drainage

- + - Drainage (Run MO)

+ Wetting (Run #11)

' -. - Drainage ! (Run#lZ) , ~ W e t t i n g

(Run #13) ; - - * - - Drainage I (Run #14)

/ -t- Wetting (Run #15)

0.00 0.10 0.20 0.30 0.40 0.50 0.60

Hydraulic gradient

Figure 3.9 - PCE flow rate versos upward hydraulic gradient for pool height of 85 mm in porous media (#16 silice sand) at interfacial tensions of 0.029,0.0075, and 0.0050 Nlm.

nuis rather than the wenuig nins performed in sand. The difference in experimental

method between researches could explain this occurrence. The experimental

methodology in Chown (1994) stated that drainage and wetting nins were separated with

a high upward water gradient and then reduced the gradient to zero to initiate the wetting

m. The author suggested that this was a resdt of traasient capillary pressure effects in

the hcture plane. The experiments in this study were conducted with an incremental

decrease of the upward gradient for the drainage runs and immediate incremental increase

in gradient for wetting conditions would eliminate the transient effects observed by

Chown (1994). Non-wetting flow channels were prevented fkom rapidly breakhg off into

discomected blobs and ganglia, so that the relative permeability of the hcture neiwork

was not changed midway through testing.

The flow rates calculated for the sand and sandless nuis in this study show similas

patterns in that drainage flow rates were lower than wetting run flow rates for both cases.

The slope patterns for the sandless runs were sunilar to those observed for the sand nuis

but the magnitude of the PCE flow rates were much smaller when the non-wetting phase

is pooled directly above the hcture network.

3.5 Conclusions

The hcturing method presented in this study can be used to generate hctured rock

samples for use in bench-scale studies. The cubic relationship was utilized to describe

flowrates and to detemüne effective parameters for quantifyllig hcture aperture and

hydraulic conductivity. The spatial distribution of hctures in this network were well

defhed and conûibuted to the understanding of flow paths and transport in the fractured

block. Several points dong the fiacture traces were identified as major contributors to

flow, especially at hcture junctions.

Flow behaviour in a rough-walled hcture network may be analagous to fiow in a single

rough-walled hcture, assuming that channel structures dominate flow. For well-mated

fracture networks under confinhg pressure and significant contact area in the hcture

plane, a channel model may be the ben mechanism to describe flow of one and nvo-

phases.

Upward gradients can arrest downward mobilization in hcture networks. The arresting

gradient is dependent on the non-aqueous phase pool height above the hctures. First

entry into the network for an initiaily water saturated condition is also directly related to

the pool height of DNAPL present. The non-aqueous phase liquid downward flow rates

were determined to be dependent on the pool height and the interfacial tension between

fluids.

3.6 References

Billaux, D. and S. Gentier, 1 990. Numerical and laboratory studies offlow in uj-acture, Rock Joints, 369-373.

Chown, J.C., 1994. "The use of upward hydraulic gradients to arrest downward DNAPL migration in rock fractures", M-Sc. thesis, Queen's University, Kingston, Ontario.

Chown, K., B.H. Kueper and D.B. McWhorter, 1997. The use of upward hydrauiic gradients to anest downward DNAPL migration in rock fhctures, Submitted to Journal of Ground Water, In press.

Fourar, M., S. Bories, R. Lenomand, P. Persoff, 1993. Two-phase flow in smooth and rough hctures: Measurement and correlation by porous-medium and pipe flow models, Water Resources Research, 29(1 l), 3699-3 708.

Freeze, R.A. and J.A. Cherry, 1979. Grounihater, Prentice-Hall, New York.

Gale, J.E., Cornparison of coupled hcture deformation and fluid flow rnodels with direct measurernents of hcture pore structure and stress-flow properties, 28th US. Symposium on Rock Mechics, Tucson, AZ 29 June-I July 1987, pp. 12 13- 1222.

Hakami, E. and N. Barton, 1990- Aperture measurements and flow experiments using transparent replicas of rock joints, Rock Joints, Bakema, Rotterdam, 383-390.

Iwai, K., 1976. "Fundamental studies of fluid flow through a single fracture", Ph.D. thesis, Universis. of California, Berkeley, 208 pages.

Kueper, B.H. and D.B. McWhorter, 1991. The behavior of dense, nonaqueous phase liquids in hctured clay and rock, Ground Water, 29(5), 7 16-728.

Kueper, B.H., C.S. Haase, and H.L. k g , 1992. Leakage of dense, nonaqueous phase liquids fiom waste impoundments constnicted in hctured rock and clay: theory and case history, Canadian Geotechnical J o u d , 29,234-244.

Mackay, D .M. and J. A. Cherry, 1 989. Groundwater contamination: Pump-and-treat remediation, Environmental Science and Technology, 23(6), 63 0-636.

Marsily, Ghislain de, 1986. Qmmtitative Hydrogeology, Academic, San Diego, California.

Muzzin, J.J., 1995. "Flow properties of a hcture network", B.Sc. thesis, Queen's University, Kingston, Ontario.

Myer, L.R., A.M. Cook-Polek, L.J. Pyrak-Nolte, and C. Marone, Mercury porosimetry studies on a naturai hcture, In Proceedings: 4th Annual International

Confrence on High Level Radioactive Wuste, Las Vegas, NV, 26-30 April 1993, 20 1 7-2022.

Pankow, J.F. and J.A. Cherry, 1996. "Dense chiorinated solvents and other DNAPLs in groundwatery7. Waterloo Press, Oregon, U.S.A.

Pemell, K.D., M. Jin, L.M. Abriola, and G.A. Pope, 1994. Sdactant enhanced remediation of soi1 columns c o n h a t e d by residuai tetrachloroethylene, Journal of Contaminant Hydrolog)r, l6,35-53.

Reitsrna, S. "Laboratory measurement of capiuary pressure-saturation relationships in naturai rough-waiied fkictures", M.S. thesis, University of Waterloo, Waterloo, Ontario, Canada, 1992.

Reitsrna, S. and B .H. Kueper, 1994. Laboratory measurement of capillary pressure- saturation relationships in a rock fkacture, Water Resources Research, 30(4), 865- 878.

Schwille, F., translated by J.F. Pankow, 1988. Dense Chlorinated Solvents in Porous and Fractured Media: Mode1 hkperiments, Lewis, Chelsea, Michigan.

Schrauf, T.W. and D.D. Evans, 1986. Laboratory stuclies of gas flow through a single natural fracture, Water Resources Research, 22(7), 1 O3 8- 1 050.

Snow, D.T., 1970. The frequency and apertures of hctures in rock, International Journal of Rock Mechanis cind Mineral Sciences, 7,2340.

Tsang, Y.W. and C.F. Tsang, 1987. Channel mode1 of flow through hctured media, Water Resources Research, 23(3), 467-479.

CONCLUSIONS AND RECOMMENDATIONS

4.1 Conclusions

The hcturing method presented in this thesis can be used to generate various hctured

rock samples for use in bench-scale studies. The cubic relationship was utilized to

describe flow rates and to detennine effective parameters for quantimg hcture aperture

and hydraulic conductivity.

Upward hydraulic gradients are able to arrest downward DNAPL migration in a rock

hcture network for both scenarios examined; that of a lagoon situation and of an

aquiferhedrock configuration. Variation of the pool heights of immiscible liquid (PCE)

emplaced alone above the fkacture network were completed at five thicknesses: 35, 60,

85, 100 and 115 mm. For an incrûashg thickness of the DNAPL pool, entry into the

hcture network occurred at larger upward gradients during drainage m. The rneasured

relationship between wetting and drainage nins was hysteretic, and, as a result, arresting

gradients during the wetting nin were generally higher than the entry gradients during the

drainage run for a given height. At the 85 mm pool height without porous media, the

arresting and entry gradients were the same, however, the 80w rates for PCE were higher

for the wetting conditions. When comparing the PCE flow rates at a specific hydraulic

gradient for a wetting-drainage pair, the clifference in flow rate seemed to be greater at

larger pool thicknesses (i.e., hysteresis appeared more pronounced at higher pool

thickness).

The experimentd nins completed with porous media present were conducted with an 85

mm pool height in the silica sand layer. Progressive decreases in interfacial tension

between fluids altered the entry and arresting hydrauiic gradients and the non-wetting

phase flow rates increased. Flow rates for the wetling and drainage nms were similar to

those observed for the sandless runs in geneml trend. The sand nins differed nom those

of Chown (1994); crossover of flow rate wetting-drainage curves observed for the single

hcture situation were not apparent in this study.

Flow behaviour in a rough-walled hcture network may be analagous to flow in a single

rough-walled fracture, assuming channel-dominated flow. For well-mated fi-acture

networks under confining pressure and significant contact area in the fiacture plane, a

channel mode1 for an effective single hcture may be the best mechanisrn to describe

£low of one and two-phases. It is important to note, however, that the Gactw

distribution for a fracture network may be different than for that of a single hcture.

4.2 Recommendations

Observations made fiom one-phase flow tests on another fracture network in Muzzin

(1995) indicated that fiac~ire junctions have signincant effects on flow. Primary flow

conduits at multiple hcture junctions were observed during initial saturation of a

network. Further study of hcture network systems, as opposed to single hcture studies,

may indicate that junctions may shift statistical aperture distributions fiom a lognormal

relationship to one where skewness is not apparent (Le., one which does not favour

smaller openings). However, in al1 but the most densely hctured media, the number of

junctions would be low in cornparison to the number of contact points dong the hcture

planes in the unit. More study is required to determine the influence of hcture junction

areas and how they influence flow.

The realistic, naturai hcture networks that were obtained fiom this procedure provide

excellent tools for M e r laboratory investigations. The availabiiity of these controlled

specimens enable resin injection and fkcture network imaging methods to be applied.

These would advance the accuracy of statistical distributions used to describe fracture

orientation, length, aperture and density. Further cornparisons between single and

multiple fracture flow behaviour may be made with more certainty.

Despite the determination that upward water gradients are able to arrest downward PCE

flow in a rough-walled, rock hcture network, additional work is needed for a better

understanding of the exact mechanisms involved. A more comprehensive study of

interfacial tension af5ects on two-phase flow in a fiachue network will be valuable to

confimi the prelirninary conclusions fond in this shidy. Alteration of the flow ceil

apparatus to better facilitate the addition of different aqueous solutions should be

completed if this work is to be attempted.

The engineering design involved with establishing an upward hydraulic gradient across a

hctured rock or clay unit at a field site may prove to be difficult. Obviously, the data

collected in this laboratory study measured ideal conditions for upward gradient

application across a relatively small hctured unit, where flow was well-directed and

controlled in an upward orientation. Fwther research might include the design of upward

hydraulic gradient systems in the field across fkactured units, including the measurement

of water pressures at various fracture traces dong the surface of the formation.

While Chown (1994) presented results which supported the theory of emplacing a

'hydraulic site bottom' to prevent downward remobiiization of a DNAPL pool during a

chexnical flood in a single fkacture, the additional data provided by the study of cross-

cutting, n a d hctures in a n e ~ o r k configuration further supports this conclusion.

Further study involving fiacnire networks of different rock types, roughness and aperture

are important steps fonvard in this area of research, as weil as larger scale tests.

Appendix A Interfacial Tension and

Surface Tension Measurements

Figure A.1- Surface tension measurements for 2% polyoxyethylene sorbitan ester solution.

I Surfactant-air Interfacial tension l ~ Surfactant Solution Concentration (mgR)

O 4 10 14 20 40 1000 Interfacial 73.4 63.8 55.9 53.1 52.7 44.2 39 Tension 72.2 62.1 55.8 52.7 52.1 44.9 39.1

(dynes/cm) 72.9 =.O 56.3 52.5 51 .8 44.0 39.1 41 -7 41 -6

Averaae 72.8 61 .O 56.0 52.8 52.2 44.4 40.1

Figure A.2 - Interfacial tension measurements for 2% polyoxyethylene sorbitan ester-PCE system.

Surfactant-PCE lnterfacial tension

Surfactant Solution Concentration (rng/L) O 4 10 14 20 100 1000 20000

Interfacial 30.4 19.7 15.6 14.3 14.4 14.4 9.6 7.6 Tension 25.6 19.6 15.9 15 14.5 14.1 10.1 7.5

(dynesfcm) 29.5 19.3 15.6 14.9 14.7 14.0 10.0 7.5 30.2

Average 28.9 19.5 15.7 14.7 14.5 14.2 9.9 7.5

Figure A 3 - Surface tension measurements for polyoxyethylene sorbitan esterlethano1 solution in a 15 weight percent ratio.

Cosohrent-air surface tension I Cosoivent Solution Concentration (rng/L)

O 12 24 60 120 1200 lnteffaaal 71 -4 66.3 61 .O 56.5 51.3 44.2 Tension 71 -3 66.2 61 .O 56.9 50.7 45.4

(dyneslcm) 70.6 66.9 60.5 56.8 50.9 45

1 Average 71.1 66.5 60.8 56.7 51 .O 44-91

Figure A.4 - Interfacial tension measurements for polyoryethylene sorbitan esterjethano1 solution in a 1 5 weight percent ratio with PCE.

1 Cosoivent-PCE Interfaaal tension 1 Cosohrent Solution Concentration (mgk)

O 12 24 60 120 1200 120000 Interfacial 23.6 21 .O 19.2 15.8 14.4 11.8 4.9 Tension 23.8 21 -1 18.9 15.5 14.2 11.7 5.0

(dynedan) 23.5 20.2 18.6 15.9 14.9 11.7 4.9

Average 23.6 20.8 18.9 15.7 14.5 11.7 4.9

Appendk B Single-Phase Flow Test Results

Figure B. l - Hydraulic aperture data

The hydraulic aperture, &, for the effective fkcture opening is calculated using:

where p is the dynamic viscosity of water (0.0015 Pas), Q is the flow rate in metre3

second-' for each measurement, p is the density of water (997 kg/m3), g is the

gravitational acceleration (9.806 m/s2), w,n is the effective hcture width (0.497 m), and

Vh is the hydraulic gradient flowing through the network.

The Reynolds numbers presented are calcdated using (Marsily, 1986):

where q is the specific discharge of water, and 6, is the effective hydraulic aperture of the

Appendix C Data from Two-Phase Flow Tests

Runs #lm15

Table C.l- Data from Run #1; 35 mm pool height under primai). drainage conditions (November 5,1996).

Chrono Cumul. PCE Pool Water flow Flow Water Comm. Gradient Real Tirne Time vol. Flow rate Height time tirne ffow rate #

time (min) (s) (min) (ml) (mumin) (mm) (min) (s) (min) (mumin) 0.70 11:lO -1 134 n

Chrono Cumul. PCE Pool Water flow Flow Water Comm. Gradient Real Tirne Time vol. Flow rate Height tirne time ffow rate #

time (min) (s) (min) (ml) (mumin) (mm) (min) (s) (min) (miimin) 21 :20 -524 32.78 8.55 58.50

Chrono Cumul. PCE Pool Water fiow Flow Water Comm. Gradient Real Tirne Tnne vol. Flow rate Height tirne time flow rate #

time (min) (s) (min) (ml) (mumin) (mm) (min) ( 5 ) (min) (milmin) 163 30 163.50 370 2.37 35

850 57

NOTE: 'Water flow t h e ' measurements for al1 runs are timed for filling 500 ml d e s s otherwise specified in the comments section.

Run #l - Cumulative PCE volume vs. time Drainage - 35 mm pool height

Tïme (minutes)

Figure C.l- Run #1 data; 35 mm pool heigbt under primay drainage conditions

Run #l - Comments November 5.1996

Drainage; 0.035 m pool height; initial water gradient i = 0.7

1 1 : 10 pump on for i=0.7, no bubbles or debris seen exiting the hcture. Overflow at 165 mm above the rock face. Approaching or at steady state water flow Wi11 srart nui soon, water supply depleting rapidly at this gradient. Valve 1 & 7 opened. 12:04 pool fully established at 3.3 cm. Pool bubbling rapidly. Water bubbling through locations 7,6,5 at about 1 drop / S. Bubbles at 7 sometimes migrate to 8. Drops are about 1 cm in diameter. Water bubbling through locations 1,3,4 at 2 drops / S. More activity along 2-1 -4 fracture than at 7-8-6-5 (rate higher), however at right side, 1-3 line also has a high rate of water exiting fracture. Lab temperature at 235°C. Oscillating surface of PCE at 0.034 mm. Lab temperature at 23.0°C (wiodow opened at 12:20). WiIl need to change water carboy soon - down to half of fint section, about 2.5 L. NB: re: #4/5 - Valve 1 opened fidl caused PCE to pour out very quickly; next nia, open partially. Checked bottom with flashlight, no sign of PCE - looks Iike pre-run conditions. Bubbles form at surface of rock and migrate inward (toward " 1") along hc ture and break off some distance closer to 1. NB: Will use O- 1 increments in water gradient to 0.5 because of concern for volume in water and soluble waste containers. Changed water carboy. Lab temperature 22.5 OC. 5 s to change gradient and get back to observe. Bubbles at 7 & 8 coming out, no migration. Decreased migration in geneml - more migration at 1-3 but shorter distance than before. Started t h e late - use 475 ml instead of 500 ml for flow rate determination. NB: water ovedow at 164 mm. No drops fiom bottom. Lab temperature 22.0°C - 22.5 OC. Rationale for 1 hour wait: pool height extremely constant; source cut off; no drops visible from bottom; waste and water concern. Photos at #6 of top reservoir. No drops. Didn't notice before but pool could be higher than 34 mm - between 34 and 35 mm, hard to determine due to oscillations. Lab temperature 23.0 OC. Changed gradient. No drops. Drops visibly slower from 0.7 No drops. No drops. Water bubbles considerably slower. Perhaps should not have changed gradients so soon. At this i, will try and wait until water fiow rate levels out. Water level in upper reservoir 163 mm; changed water carboy.

No drops. Tina suggested that volume collecting in T junction be subtracted fiom 500 ml for flow rate calculation. No drops. Gradient change about 3 s long. No drops. Bubbles out of top face at 7,8,5,1,3,4. Bubbles start at 6, go to 5 (about 2 cm travel path); start at 2, go to 1; start at 3, move closer to 1 (about 3 cm îravel path). Most rapid movement at 1. 1 drop / 2s at 8; 1 drop/s at 3; 2 drop/s at 1 ; 1 &op 1 2 s near 1 (2); slower rate at other points. 2a,8,lY3 seem to be major pathways. For this run, will have to watch pool height carefdly since the pool is not connected to tank - not true constant head; need to adjust valve 1 for pool height. No drops. Note: Difference in 34 and 35 mm heights due to oscillating pool surface. Does not appear to have decreased in height. Changing water carboys at -1 7:3O because a gradient change at 18:OO. Changed water carboy 17:43; lab temperature 23.5 OC; carboy to deair at 17:47. Wiil change gradients due to water concem. Water still bubbling through top - expected (perhaps) an equilibrium. 1,2,3,4,5 still bubbling at 1 &op/s ("1" at slightly higher rate). '2"at "2a" - i.e. closer to " 1 " than original "2". Very slow bubble out of 7 - - 1 &op every 10 S. Lab temperature 23.5 OC; water overfiow in upper reservoir at 163 mm. 19:23 Carboy of water leaking onto floor; will now use DNAPL source water as water carboy. Batteries corroded in the flash of my camera - not working. No drops; "8" 1 &op 1 2s, "7" 1 &op 1 5 s; "6" migrates to "5" 1 drop 1 4s; "1" and '2a" 1 &op/s; "2a" migrates to "1"; "3" 1 drop / 2s; "4" 1 &op / 2s; Surface at 34 mm. Lab temperature 23.0 OC. Lab temperature 23.5 OC; bubbling steadily. No drops. "8" 1 drop 1 3s; "7" 1 drop / 1 Os; "1" 1 &op / 2s; "4" 1 drop 1 s; "2a3', "4" 1 drop l 3s Huge spark and noise, flash of lights (over oven and balance area). Investigating - circuit breaker on oven? Continuous watch for 40 min - investigation above about 2-4 min. No drops, water still bubbling. Do not expect to see drops out bottom. "8" 1 drop / 4s; "7" 1 drop / 14s; "6" to "5" 1 &op 19s; "3" 1 drop 13s; "1" 1 drop /s; "4" 1 drop / 14s; "2a" 1 drop / 2s. Pool much more stable (longer wavelengths oscillating). Bubbling looks slower; the faster set of points slowed. Pool overflow in upper resewoir at 16 1 mm. Knocked T juoction attaching venting tubes while flow test going. No drops. Upward water at 1,8,3,2a - bubbling 1 &op / 2s (al1 4 combined). Very little water overflow; valve 6 leaking; upper resemoir at 161 mm. Note: Was estimate of entry pressure aperture too high? If so, will 1 get breakthrough? If no

breakthrough occurs, raise pool height and do a wetting nui at 5 cm. Valve 6 still leaking into the graduated cylinder. Added 1 mm PCE to get to 35 mm pool height (oscillating surface stopped). Bubbling - rnay go to 0.1 (sooner - 3:00) to find out if breakthrough will occur at au. No drops; no bubbles. Water still able to bubble up occasiondly (1 drop 1 2-3 s - combined). Very slow overflo W.

No drops. NB: For 2nd hcture, do not start near entry pressure (estimated entry), pick middle pool height. No drops. Still nothing. Since water is stiil bubbling UP and paths wetted with water only on top surface, will proceed to 0.05 at 4:30. Anticipate wetting nin to obtain any useful data tonight. May have PCE entry into hcture (no bubbles on top "1"). 1,2,3,4 look penetrated - may be at hydrostatic equilibrïum at top of hcture). Continuous observation - no drops. Waited 1 hour at 0.5; nothing moving, going to O at 6 am Nothing out. No change in pool height (and no source), no drops, no bubbles. Drops fiom A, 1 mm in diameter - 3 or 4 at a tirne. From B also, and right of A (cailed H). Flow fiom A and H mostly. About 10 drops at a time fiom A (0.5 mm dia.), 1-2 at a time fiom H (1 mm). About 20 fiom A, about 5 fiom H (same sizes). Couple fiom B; B area more fiequent at 10 minutes (0.5 mm) 0: 1353 elapsed (6: 17 am) Still out at A and H primarily 0: 15: 16 elapsed. 2 mm drops fiom B up to 5- 10 at once. B forward (closer to glass) 2-3 mm dia. drops. 0:23:05 elapsed. Drops from 1 0:3 1 :40 elapsed. Drops fiom B are 2-3 mm dia 1 : 1 1 :43 elapsed. Now drops nom A,B, & A-B (0.25-0.5 mm dia), 1 1 : 14:48 elapsed. More fiom B (steadier) 1 :24:50 elapsed. Problems staying awake 2: 14:05 elapsed. Top &ont - bubbles Run terminated. Valve 3 opened, sucked down pool. Caused pathways at C-B-1 a d H-A-B-E.

Table C.2 - Data from run #2; 85 mm pool height under drainage conditions (November 27,1996).

Chrono Cumul. PCE Pool Water flow Lab Comm. Gradient Real Time Time vol. Fïow rate Height time Time temp #

tirne (min) (s) (min) (mi) (mVmin) (mm) (min) (s) (4 (Cm C) e=l c t

Gradient Real Time Time vol. Flow rate Height time Tirne temp # tirne (min) (s) (min) (ml) (mVmin) (mm) (min) (s) ( 9 (deg Cl

9 21.57 9.36 90 10.53 86 24.0

Run #2 - Cumulative PCE volume vs. time Drainage - 85 mm pool height

rn

-1000 -800 -800 -700 -800 -500 -400 -300 -200 -100 O 100

Tirne (minutes)

Figure C.2 - Run #2 data; 85 mm pool height under drainage conditions

Run #2 - Comments November 27,1996

Drainage; 0.085 m pool height; initial water gradient i = 0.6

0.8 gradient started at 12: 13. (Note: small air bubbles on bottom rock face - not over fractures - about 16-1 mm bubbles; probably fiom water constant head tank) Pool introduced at 1 2: 1 9 (valve 1 opened). Upper reservoir at 164 mm. Pool pushing out water in upper reservoir, upper reservoir at 1 68 mm. PCE tank was at 6.2 cm, now at 5.8 cm. Water overflow in upper reservoir at 1 64 mm; 163 mm. PCE tank at 5.5 cm, upper reservoir pool height seems stable at 70 cm.

ASIDE: Tank bottom at 80.5 cm above counter top; total height 86 cm to pool. Note 5.5 cm tank height and 70 cm pool height relation. Will test 8.2 cm pool height (Pc = 500 Pa) 12:36 Purnp fiom drum into PCE source tank. PCE tank 5.6 cm, pool height 7.5 cm PCE tank 5.5 cm, pool height 7.9 cm PCE tank 5.5 cm, pool height 8.1 cm

Pool height oscillating, at 82 mm (1258). Upper reservoir overflow at 163 mm. Water bubbling through pool, upper reservoir overflow at 163 mm. 1, lA74,8 bubbling most rapidly (Location #1 probably double rate of others.) NB: Few (1 0-20 of various sizes) drops in boaom reservoir fiom last experiment, <<5rnl. Bubbling from 1,8,6; la moving to 1 (bubbling 2/s here), also fiom 2,3,4 (less fieq at 2) Changed soluble waste carboy. Water overflow in upper reservoir at 162 mm. Bubbling fiom 1,8,3,6 (in order of fiequency); less fiequent from 7,4; la to 1. Bubbling from 1,3,8,6; some less fiequent drops fiom 7 Between 83 and 84 mm pool height - bard to tell (oscillating surface) Bubbling is noticeably slower, from 1,3,8 (1 most fiequently), also 4,7. Note that " 1 " is twice rate of either 3 or 8. Bubbling from 1,3,4,8 (fiequently fiom 1). Water overflow in upper reservoir at 16 1 mm. Bubbling fiom l at Ils. 3,4,8,6 bubbling - 1/5s in each location. Note movement fiom 1 a and 3 toward 1 in addition to drop emanating straight through " 1 " area. No sign of drops fiom bottom, expected to see some residual perhaps. Waterflood and lack of pool probably sufficient to bring residuai to insignificant amounts. Half hour continuou watch, no drops. Pool height at 85 mm however l ook to be increasing very slightly. Hypothesis: water overfiow decreased, i.e. water above PCE pool decreased, so less pressure acting on pool fiom above and tank letting more flow. No bubbling fiom top.

Pool still, pool height at 86 mm, water in upper reservoir at 161 mm. View from top clearly shows fracture traces. when water bubbling through .75 cm wide m o u d on each trace. Seems that water / PCE equilibrium somewhere in fracture length. Constant watch. Upper reservoir at 160 mm. Fracture traces more pronounced along portions with narrow apertures. Flow fiom A,B,H (1 mm drops). 258 - drops sporadic, little LLbursts" of flow A-B (1 mm dia. bubbles); H (2 mm bubbles). 3:03 - More steady stream out (for 1 min duration then nothing for 1 minute). 3:O7 - 1 / 2 4 s 3:lO - Flow quicker - 1 14 s 314 - 1 150 s Residual?? 3:24 - Flow not evident 3:25 - Little "burst" of flow afier minutes - I 1 6s, 1 1 8 s 3:29 - Slow again. 3:34 - 1 drop i n 2 min. 3 :42 - Started f i e r 12 min of nothing 3% - Little burst 1 / s for 30 s Very sporadic movement. Burst 1 / s or 1 1 2 s for 30 - 60 s then 10 minutes without a drop. Could be small blobs of residual fkom last nin or finger on primary flow path that extends down ahead of fiont but is "mapped off' by upward water action. Either case constitutes no "flow" - not a connected pool. Will change gradient at 4:00 as planned. 3 59 - Haven't seen any more drops. B-A-H, A-B flow. I as well at 1:30 (chrono) Large bubbles fiom B (2-3 mm). Steady stream from A-B & A ( 1 mm). PCE pump on, pool height at 85.5 mm. Off in 30 S. Water overflow at IBO mm (1 59.5 mm). PCE pump odoff at 39.4 1. Pump on 450. Off within 1 minute. Pump on 5:OO. Drop hanging from C-J. Flow started fiom B-E. Pump on. Note: has been tunied on when pool goes to 85.5 mm Drop staaed at J (2 mm, 1 point). 1 :O9 - Flow £rom E-F (1 mm, 1 point). Turned pump on too high - 90 mm pool height. Drop at F. Pool height at 87.5. Upper reservoir at 157 mm (hi& pool height forced out water, then pool lowered). NB: Look at flow rates for this gradient from this measurement fo rward. Run terminated.

Table C 3 - Data from run #3,85 mm pool height under wetting conditions mecember 11,1996).

Chrono Cumul. PCE Pool Water flow Lab Comm. Sradient Real Time Time vol. Flow rate Height time Tirne temp #

time (min) (s) (min) (mi) (mumin) (mm) (min) (s) (min) (deg C ) 0.80 10:oo 22.0

Chrono Cumul. PCE Pool Water flow Lab Comm. Gradient Real Tirne Time vol. Flow rate Height time Time temp #

time (min) (s) (min) (ml) (mumin) (mm) (min) (s) (min) (deg C ) 33 44.55 1800 40.40 86 22.0

Run #3 - Cumulative PCE volume vs. time Wetting - 85 mm pool height

Tirne (minutes)

Figure C.3 - Run #3 data; 85 mm pool height under wetting conditions

Run #3 - Comrnents December 1 1, 1996

Wetting; 0.085 m pool height.

NB: First wetting nin performed prior to this run; data not included due to experimental problems.

i=0.8; pool established in upper reservoir d e r first flow test. Pump on at 10:OO (valve 2 on). Upper reservoir at overfiow now 165 mm. Opened valve 1, no PCE out - tank height at 5.2 cm. Tumed on PCE pump to mise tank height. Tank height to 6.2 cm, opening valves 7,l. Pool height at 80 mm, bubbling rapidly. PCE tank height = 5.6 cm. Flow after PCE pool emplaced; water in upper reservoir at 1 64 mm. PCE height increase when i = O, to 86 mm. Drops from H,A,A-B,B,B-E,EF,CJ,I Water in upper reservoir at 159.5 mm. Water at f 60 mm. Drops fiom A,AB,B,H. Occasionally fiom EF. Hanging drops h m J. Pulsing fiom B? Much more sporadic bursts ffom EF, BE H,A,AB - 1 mm drops, puises fiom B At gradient change, flow just from A@. Flow of drops almost arrested. 1/s fiom A@. c lmm dia Four hanging drops from J. - 3mm dia Note: Will likely be impossible to d e t e d e a PCE flow rate due to sporadic drops or bursts. 1 55: 13 (chrono) drop fioxn AB, 1 mm dia. 1 : 5 6:3 4 (chrono) drop fiom AB, 1 mm dia. Drop. NB: Upper reservoir at 159 mm, pool at 86 mm. Bubbles at 3,1,5,7,8 and 3 dong 1-2, 1 bubble at 4, 1 bubble 1 cm left of 1. Upper reservoir at 160 mm, pool to 85 mm; no water overflow. PCE tank height at 4.6 cm. Pool at 85 mm with bubbling of water upward. Pump on. No drops observed. Upepr reservoir at 16 1 mm. Pool height at 86 mm, water overflow started. Pool height at 87 mm. Bubbles fiom same locations, more fiequent. Bubble at 1 and left of 1 coalesced to form 1 wide blob 2-1.5 cm wide. ASIDE: Still thinking about reason for lower flow rates after pool settling (Le. previous nui) and redistributing ... When upward water gradient cornes through, could 0.8 water gradient be suffxient to "push" PCE into smaller hc ture channels (i.e. provide a dnving force for PCE to overcome entry pressure of smaller hcnire channels). Rationde - main water pathway is lamest channel even though it is wetting fluid. If this happened, when water pathways becarne stagnant at beginning of wetting run, then PCE would/couid travel down that

former water pathway (with fewer paths available to it). Also, what is coalescing of PCE bubbles is prohibited in fracture? Then PCE mpped and may not contribute to flow..

2 1 5 bubbles dong 1-2, 1 a bubbling fiequently and 1,3 as well. Bubble at 7 but not rnoving, bubbles at 5-6,4 in total; bubbling at 4. Greatest water pressure at 5,8,1,1%4,3 - bubbles have formed here.

22 Upper reservoir at 161.5 mm, pool height at 86 mm. 23 Upper reservoir at 162.5 mm, pool height at 85 mm.

NB : Instead of forcing PCE pool down through kcture, will close valve 5 and let water head push PCE pool back into tank. Then, close valve 1. Proposed, 1 hour at 0.6 gradient, then close valve 5. Water builds up in upper reservoir, DNAPL pool decreases, close valve 1, open valve 3 (with valve 2 open, less PCE sucked into fracture).

24 Upper reservoir at 2 63 mm 25 End test.

Close valve 5 - Upward i to 0.8 (20:OO) Height in upper reservoir (water) = 175 mm Close valve 1, pool height = 7 1 mm (PCE) Open valve 3. PCE sucked out. Valve 3 closed and drops still corning fkom Gacnire (even with upward gradient) because water wasn't sucked out, it just wam't bubbling out the top. m e r a minute or two, drops stopped falling but before that, a duration of about 1 minute, bubbling up and drops down. Pool at 65 mm. Therefore 6 mm in pool height passed tizougn the h c t u r e and out with bottom reservoir stuff. Opening valve 5 at 20: 1 1 to get water ovemow to 163 mm. Turning i = 0.8 to i = O, Ieaving valve 2 open with pool height at 65 mm, bottom reservoir 21 mm. (as per BHK's instructions) then let pool redisûibute until tomorrow. 20: 13 Water overflow at 164 mm. i = O, flow started; pool height seems to be slightly above 66 mm. 20:22 i = O, flow at 52 mm in bottom reservoir, pool height is 63 mm. Leaving overnight to equilibrate. Water pump off, PCE pump off Valve 1,3,4,6 closed; valve 1,5 open.

Addendum: Dec 12, 1994 - 12:00 Equilibrated overnight. 54 cm pool height, 13 cm PCE bottom reservoir. Water in upper reservoir at 15 cm. Decreased water gradient to negative gradient so PCE flow resumes. Note negative gradient less than suction created by valve 3 ..

Approximate 0.05 - 0.075 negative gradient, then decreased to -0.10 Flow stopped with 33 mm in bottom reservoir, 43 mm pool height (PCE) Dec 13, 1996 - A. M. Decreased gradient until < 15 mm pool height Flow fiom H,A,AB,B J 3 E Opened valve 3 for 5 s to increase flow rate Valve 1 leaking into upper reservoir. Height in botiom resexvoir 20.4 cm. l,5,8,la cleared out on top face - Le. minimai pool of 1-2 mm everywhere but these locations Drops fiom A,AB; occasional pulse fiom B 1 mm pool height; 204 mm in bottom reservoir Will raise gradient to 0.3 and s m d bubbles out top (< tmm dia) Water in upper reservoir at 95 mm (Water is below overflow, gradient is achlaily higher that 0.3) NB: Small occasional drops out of A while residual bubbling up at i = 0.3 Bubbles and drops slowed Opening valve 3 -

Many streams of residual out while valve 3 open. No bubbling fiom top. Raising i to 0.8. Discovered that water pump was not tumed on. This could explain why more PCE bubbles did not flow up, a very small number came out. Put i back to O because 1 want to take Q rneasurements for residual effect.

Height in upper reservoir increasing fiom 12 cm at i = O. Will hini off pump at ovefflow (1 63 mm height)

Table C.4 - Data from run #4; 60 mm pool height under drainage conditions (January 22,1997).

Chrono Cumul. PCE Pool Waterffow Lab Cornm. Gradient Real Time Time vol. Flow rate Height time Tïme ternp #

time (min) (s) (min) (ml) (mVmin) (mm) (min) (s) (min) (deg C) 0.60 10:38 -862 O O 23.5 1;

Chrono Cumul. PCE Pool Waterflow Lab Comm. Gradient Real Time lime vol. Flow rate Heght tirne Time temp #

time (min) (5 ) (min) (mi) (mvmin) (mm) (min) (s) (min) (deg C)

25 42.23 25.70 100 3.89 60 23.5 32 42 32.70 125 3.82 60 23.5 39 25 39.42 150 3.81 60 23.5 47 41 47.68 195 4.09 60 23.5 49 12 49.20 200 4.07 60 23.5 59 12 59.20 250 4.22 60 23.5 4(

0.00 67 38 67.63 300 4.44 60 23.5 4' 70 40 70.67 350 4.95 60 23.5 75 13 75.22 440 5.85 60 23.5 75 51 75.85 450 5.93 60 23.5 4: 78 3 78.05 500 6.41 60 23.5 80 30 80.50 550 6.83 60 23.5 82 57 82.95 600 7.23 60 23.5 85 35 85.58 650 7.59 60 23.5 86 51 86.85 700 8.06 60 23.5 89 19 89.32 750 8-40 60 23.5 42 90 59 90.98 800 8.79 65 23.5 4 92 32 92.53 850 9.19 65 23.5

Run #4 - Cornments January 22, 1997

Drainage; 0.060 m pool height.

(Comments 1-10 re: water flood, January 21/97) Overfiow at 166 mm. Seal on valve 6 broke as well (remnants in graduated cylinder). Air bubble at A gone - will observe bubbles as flow test progresses. CHWT not constant . . . water level down to about 4 inches height in water tank because 1 left for one hou. Changing source now. Water overflow in upper reservoir at 161 mm. Note: 1557, I=1 .O ovefflow fasf changing waster water overflow at 166mrn. Level 1 inch below overflow in CHWT. 14:44:30: back to overflow. Closed valve 2, opened valve 3 for 10 s, water overflow d o m to 159 mm. Very tiny residual bubbles came out of 1 (-. l mm diameter), s m d bubbles fkom J (-1 mm diameter). Not a considerable amount. Normal 80w by 1 650. Found upper reservoir to 260 mm and lines backed up for waste. Fixed situation, changed carboy, needed to close valve 2 momentarily. About 40 L through system. Turned off valve 2, pump off, 19:32. January 22/97 Restart at 9:40 am; valve 2 open. -10L more to flush then PCE pool to be introduced.

Overflow at 166 mm, no noticeable change in PCE on top of fracture network - fiactures still clear. Changed waste carboy (soluble). lntroducing 50 mm PCE pool. Valve 7 and valve 1 open, only drips, need pumping to tank. Reduced i = 0.6 from i = 1 .O, PCE pump on. PCE dropping onto fracture face, forming non-wetting pool on top of block everywhere but along hctures until height is . 7 5 cm then filling over flow" areas of fiactures then covering these areas 1st. Water bubbles coming up and rnoving along fiacture then released up through pool into water. Front fork of PCE outlet covered in film or growth (White filmy scum-like skin on PCE pool - consisting of limestone dust as well as congealed layer.) Air bubbles in bottom reservoir not cornpletely gone. A,B,C fiee of bubbles, E and F have 3 bubbles; 2 at F, 1 at E. Rapid water bubbles up through pool in individual bubble form (Le. no ridae of water). -1-2 cm diameter (1.5 cm diameter at E, 1 cm diameter at F, 1.25 cm diameter left of F) Oniy 35 mm pool height in CHDT but 55/56 mm pool height in upper reservoir (partially restricted valve 1 opening - will see about draining from tank). Valve 6 leaking! Can get through m.

- . Water overflow at 164 mm. Much slower flow of water.

Open valve 1 completely, will let equilibrate even if pool height is above 54 mm. Height in CHDT misleading (only 3.5 cm PCE). Note: For this nui, breakthrough not expected until-0.15. Therefore will stay at gradients above 0.3 for 30 minutes and at gradients 0.3 and below for 90 minutes. Al1 gradient steps are in 0.05 incrernents. Missed reading for water flow time Very quick gradient change. Bubbling fiom 17 points. Most rapid at 3, 1, 1 a. Individuai bubbles still (no ridge). Water overflow at 163 mm. Water bubbling rapidly through pool. No noticeable slowdown. Bubbling slowed. Overflow looks to be decreasing to 162 rnm, PCE pool up to 58 mm probably. Bubbling progressively slower; water overflow at 162 mm. Bubbling fiom l,la,4,5,7; bubbles at other locations but fom sfowly and release sporadicall y. There have been 2 hanging drops at J for the duration. Bubbling at 2,1,l a,4; -Us; dso at 7 No drops out bottom. Bubbling still slow in top reservoir but continuing. Water overflow at 161 mm. Bubbling has stopped in upper reservoir; no flow out bottom. Note that there is no ridge evident on top fractures, probably hydrostatic equilibrium at some point in length of specimen or hasn't reached equilibrium yet. Continue watch until 21:15. Pool has been checked and found to be at 60 mm. No bubbling. no drops for 45 minutes, will expect flow immediately at i=0.05. Perhaps, extend time here at this gradient. Water overfiow at 160 mm. Expected flow at gradient change. No sign of flow. Vew small (-.75 mm diameter) drops out of A-B, increasing in nequency with t h e . First sign of a pulsed stream, then stopped or ratber back to periodic drops. First drop out of B, similar size to those at A-B ( - l m ) . Drops sporadic with slow bursts, al1 1 mm diameter. Exclusively fiom AB area with 5-1 0 drops fiom area B. Unsure if this is mobilized residual or finger of fiow. Fracture volume estimated to be -30mI. Could wait and see if 30 ml cumulative volume is obtained. Noticed air bubbles hanging onto PCE pool in water (see diagram 1 in lab book). Nine 1 - 2 mm diameter bubbles of air submerged in water on PCE pool. AAer 2 hours, 11 minutes OS), not even 10 ml in system [bottom reservoir]. At LOO, will change to i=0.025. Flow 1 1 s after gradient change. From H,A,B. Flow from 1 started, AB (5 areas) Drop descriptions:

H - 1 -5 mm diameter consistent size (2 released, pause, 2, pause, 2,. . .) A,- - 1 mm diameter consistent (steady stream) B - variable size, fkom < 1 mm - 2 mm diarneter (mostly very short bursts)

1 - 1-2 mm diameter, variable (bursts of 3-4 drops every few seconds) Update B - strearning regularly now, fewer bursts and size fairly consistent. Overflow at 160 mm. More flow fkom B at gradient change; releases from BI as well (release area spread). Vary fiom 1-3 mm diameter fÎom B in burstslfllow. Flow fiom BE area started (sporadic drops). Flow fiom C J area started (sporadic drops). *Turned pump on. Flow from EF area; flow from BE more steady. Pool height increased to 65 mm!! Didn't think PCE pump was on that fast. Tuming off valve 1 to get height below 60 mm, then open so time to balance out to 60 mm shorter. Opened valve 1 again valve 2 closed between 1200 ml and 1300 ml reading). LeveI nsing between 1300-1400 ml measurement. Note: Will star& wetting run once pool height is 60 mm again. Water overflow is 159 mm. Stopped watch afier 2:04:33 for Run #5 drainage. Started watch immediately (0:OO:OO) for Run #6 wetting. See "comm6.doc" for continuation of comments. Run #5 over.

Table C.5 - Data from run #5; 60 mm pool height under wetting conditions (January 23,1997).

Chrono Cumul- PCE Pool Waterflow Lab Cornm. =radient Real Time Time vol. Flow rate Height Cime Time temp #

time (min) (s) (min) (mi) (mumin) (mm) (min) (s) (min) (degC)

0.00 94 5 94.08 900 32.19 65 23.5

Chrono Cumul. PCE Pool Water fiow lab Camrn. Gradient Real Tirne Time vol. Flow rate Height time Tirne temp #

time (min) (s) (min) (ml) (mumin) (mm) (min) (s) (min) (deg C) 1 1 :O0 600 2715 60 57

Run M 5 - Cumulative PCE volume vs. tirne DrainageMletting - 60 mm pool height

Figure C.4 - Run #4/#5 data; 60 mm pool height under drainagelwetting conditions

Run #5 - Comments Janwry 23,1997

Wetting; 0.060 m pool height.

Stopped watch after 2:04:33 for Run #5 drainage. Started watch immediately (0:00:00) for Rm#6 wetting. Put water in top reservoir to change water overflow level fiom 155 mm to 157.5 mm. Using valve 1 to regulate PCE into upper reservoir since measured f3ow reservoir d g out [?]. Keeping PCE height between 60 - 61 mm in upper reservoir. Flow fiom H,A,AB,B,BI,I; Note flow fiom CJ,BE,EF ceased with 60 mm pool height resumed. Water overflow at 157.5 mm. Half millimetre increment due to fluctuating pool height. 35:22 (chrono) PCE pump on. 36:22 (chrono) pump off. After 2 minutes fiom gradient change flow considerably slower, drops smdler. B - spo~adic flow fiom steady £iow before gradient change. A,AEl,H - less fiequent flow. 1 - stopped. Al1 "steady" flow has ceased, A,-, H have sporadic drops ananating (-1 mm diameter). Average l/s fiom al1 spots combined. No bubbling seen in top reservo ir. Spomdic 1 mm diameter drops £tom AB. Occasional bubble from 1. Nearly hydrostatic equilibrium but, what 1 assume to be residual, PCE dropping and upward water has pathway. Water overflow at 158 mm at 4:30; bubbles in pool started. Water overflow at 161 mm at 6:10; pool height at 55 mm. Slow bubbling up thTough pool. B y 6: 10, drops stopped, gradient increased. Water bubbling up more rapidly. Water overflow at 164 mm; water bubbling rapidly. I l :O0 - Run #6 terrninated.

Valve 7 closed, valve 1 closed. Gradient back to zero and pool will drain @umps off).

Table C.6 - Data from run #6; 100 mm pool height under drainage conditions (January 29,1997).

Chrono Cumul, PCE Pool Waterfiow Lab Cornm. Gradient Real Tirne Time vol. Flow rate Height time Time temp #

time (min) (s) (min) (ml) (rnlimin) (mm) (min) (s) (min) (deg C) 41 -07 1.68 22.5

Chrono Cumul. PCE Pool Waterfiow Lab Comm Gradient Real Time Time vol. Flow rate Height tirne Time temp #

t h e (min) (s) (min) (ml) (mumin) (mm) (min) (s) (min) (deg C) 23:11 -1 9 O 1 O0 20.5

Run #6 - Comments January 29,1997

Drainage; 0.10 rn pool height.

Flow test 500 ml in 1 :4 1.07. Water overflow at 166 mm. Flow test 500 ml in 1 :39.54. Water overflow at 166 mm. Tank height at 3.7 cm. Gradient set, valve 7 and valve 1 still ciosed. Water ovexfiow at 165 mm. Taking 2 flow readings before PCE introduced to compare difference at i = 0.6. Didn't go at 1 1 :40 because wanted to change waste and source carboys. Opening valve 7 and valve 1; establishg pool. Main pathways last to cover over with PCE (pool forms around hcture traces, until height is -0.75 cm). Outiet valve seems to be blocked - could be skin layer on PCE which coats screen when pool is drained or could have growth on screen. Since "scum" is seen coating walls in upper reservoir, likely this option. Very slow filling in upper reservoir but don? want to go beyond pool height. Turning PCE pump on. Pump off. Water overflow at 165 mm. Pump on (Pump off 12:29) (Pump on 12:30). Water nearing top g l a s in PCE tank. Pump off at 1 2 3 . 42 mm height in CHDT. Water overfiow at 163 mm Letting pooYtank equilibrate (10 cm pool height close). Water overflow at 163 mm. Bubbling faVly rapid nom defined parts of 80w path. BubbIhg slowed slightly. 1,3, l a bubbling most rapidly, dso bubbling from every other labelled location. Slight ridge evident between bubbles dong hcture. Rate of bubbling slowed. Water overflow at 162 mm. Looks like pool has gone dom to 100 mm, also valve 6 with redaced O ring looks like it is leaking; water ovefflow at 161 -5 - 162 mm. Will turn PCE pump on since pool height decreased. Pump off 19:03 (-2 min) 2 mm rise. Bubbling very slow. Bubbles every few seconds fiom only main pathways, there are fewer sites of bubbling and a slight ridge between bubbles. Water overfiow at 16 1 mm. PCE pool stopped bubbling; water overflow at 16 1 mm; watching for bubbles. No bubbles travelling up through water but ridge apparent and stationary bubbles at 1,1 a,3,4,8,6,7. Watched for 30 minutes, no drops - bubbles d l apparent in top resentoir. Because of past experience, no drops will fa11 until bubbling has ceased. Pump on; pump off 21 5 6 (on for only 30 s, height increased 2.5 mm).

Used 10 ml syringe in upper reservoir to extract 6 x 10 ml of PCE, so pool height back to 100 mm from 102 mm. Changing gradient since pool height adjustment complete; water overflow at 159 mm (will add water to 16 1 mm). Ridge gone except in 1,l a,4 area - slight indication of ridge. Water level increased to 16 1mm by dripping in top air vent. Water overflow at i 60 mm. Flow! At change of gradient. Coming fiom AB,A,HB; looks like flow, not residual by speed and fkequency of drops. Flow fiom 1 too; steady stream fiom AB. Majority of flow fiorn AB,A,.H. Noticed flow slow, pool to 98.5 mm. Tumed pump on for 10 S.

Now sp-, non-steady flow and slower. 99.5 mm pool, pump on 10 S. At 48 minutes, 2 s, flow sped up, height up 1 mm; seems to be difference between being above 100 mm and below 100 mm. 100 mm pool, pump on for 5 s; pool height to 101 mm, flow increase. Note: Calculate volume of lmm height in upper reservoir - see if it approximates volume in bottom reservoir after drop off. 1:09:30 - pump 5 s (Ievel was at 99.5 to 100 mm). Flow sped up, then slowed. 1 : 19: 12 - level at 100 mm dead on; flow slow (not flow, just spurts) Flow f?om H,A,AB,B,C,I,BE,.BI. Steady streams, larger fkom B and C. Flow kom lefi of "e"; went too long with pump. Pump 5 S. *+ (5s for each astensk). Water overflow at 158 mm From left of E again and F Flowing fiom H,A,AB,B,C,J,I (al1 locations as before) at i = 0.1 Al1 locations flowing. Flowing quickly from H,A,AE3,B, now stopping 5s later.

Bubbling very slowly in upper reservoir. Water overfiow at 16 1 mm. Upper reservoir bubbling in major paths however occasional drop out of bottom (-1 mm diameter drops). Bubbling rate noticeably higher with gradient change. Water overflow at 162 mm; bubbling increasing - more fi=equently fiom same paths. Water overflow at 162 m. Water overfiow at 1 62 mm; overflow not yet measurable; bubbles not migrating more than 1-2 mm, slight ndge evident between bubbles. Increase in bubbling rate. Photo. E h terrninated. (Valve 2 off, valve 7 and valve 1 off) 8: 15 Valve 3 open to drain lower reservoir. Waste Ml, valve 3 closed, valve 2 open to fil1 upper reservoir. Valve 2 closed, valve 3 open combinations so upper reservoir always has > 1 cm water on top of fracture.

rable C.7 - Data from run #7; 100 mm pool height under wetting conditions (January 30,1997).

Chrono Cumul. PCE Pool Waterflow Lab Cornm. Gradient Real Tirne Time vol. Flow rate Height tirne Time temp #

time (min) (s) (min) (ml) (mumin) (mm) (min) (s) (min) (deg C) 0.00 128 47 128.78 1600 67.69 100 22.5

Chrono Cumul. PCE Pool Water flow Lab Comm. Gradient Real Time Time vol. Flow rate Height time Time temp #

time (min) (s) (min) (ml) (mumin) (mm) (min) (s) (min) (deg C) 7:01 45 1 391 0 100 8 58.5 8.98 21.5 45 7:15 465 3910 100 8 48.73 8.81 21.5

0.60 7:30 480 3910 1 00 21 .O 7:31 481 3910 IO0 7 9.7 7.16 21.0 759 509 3910 100 7 10.68 7.18 20.5 50

Table C.8 - Data from run #8; 115 mm pool height under drainage conditions (Febmary 18,1997).

Chrono Cumul. PCE Pool Water flow Lab Comm. Gradient Real Time Time vol. flowrate Height time Time temp #

time (min) (s) (min) (mi) (mumin) (mm) (min) (s) (min) (deg C)

0.60 9:40 -560 n n CL- A 1

Chrono Cumul. PCE Pool Waterflow Lab Comm. Gradient Real Time Time vol. Flow rate Height time Time temp

time (min) (s) (min) (ml) (rnVrnin) (mm) (min) (s) (min) (deg C) 3 33.5 3.56 40 11.70 114 23.0

Run #8 - Comments Febniary 18, 1997

Drainage; 0.1 15 m pool height.

Pump on for water at 9:40, valve 2 open. PCE pump on at 954; 32 mm height in CHDT at start. At 10:OO began to take off water head f?om CHDT (PCE pumped to tank and water overflow). Tank height at 45 mm. Opening valve 7, valve 1 (tank height = 45 mm). Flow out of both forks, slower Eom front fork (it is higher in elevation dian back). Simila. pattern of coverage order on top h c h w face. Will let tank and upper reservoir equilibrate with PCE so target is not exceeded. Level ham't changed in minutes, tuming PCE pump on (note: tank at 39 mm height). Pump off. Water overfiow at 163 mm Water bubbling fiom:

4 bubbles (active) dong 6-5 4 bubbles (active) dong 7-8 Migrating bubble at la & 3; about 1 cm travel, with 1 cm ridoe dong fr?cnire. Bubbling fastest fiom 1 Bubble at 4

Water overflow at 162 mm. Bubbling pattern very similar but slightly slower. Missed flow reading. Changed water source carboy. Bubbling noticeably slower. Missed reading - stopwatch dropped on fioor and reset Missed reading - phone d l . Bubbling noticeably slower. Pump on too long. Height at 1 17 mm in upper reservoir. Used syringe to remove -50 mi, level now at 115 mm. Bubbling almost stopped. Very slow bubbling. Bubbling up stopped at gradient change. Ridge at la visible; no ndges or bubbles seen at other points on hcture face. Watching lower reservoir for flow. Water overfiow at 160 mm. Watching bottom reservoir since gradient change, no drops. 4 bubbles, stationary, dong secondary fiachire. Fracture is parallel to 1-3 but closer to fiont. It appeared d e r the apparatus implosion. Very small aperture and have not observed water flow out of this area before. Also, a bubble is visible and stationary at the inclusion site on the rock face. Note 1 mm decrease in pool height. Turned pump on. Turned pump on, 1 mm decrease in pool height. Level up to 115 mm; no drops, no bubbles.

Pump on, level to 1 14 mm; now at 1 15 mm Bursting has started Çom B, ABA; -1 mm diameter drops. Pace seems to be picking up after 2 minutes but still not measurable quantities. Very random drop patterns, extremely small volume, less than 10 ml in 80 min and 30 sec. Flow started fiom H, A, AB, B; varied sizes; dso flow fiom 1 Five paths plus 1 less fiequently. Pump on, now at 1 l7mm. Also flow fiom C. Water overflow at 159 mm. Flow Çom BE area started; now 7 reguIar paths. Larger drops imrnediately at gradient change and more pathways; there are 8 pathways now, 2 new areas because BE stopped, now BE starhg again, so 9 areas or paths. Largest drops nom BI,B,C,CJ. Flow fkom EF Flow fkom F Two paths at EF now. Water overflow at 157 mm. i=0.10, flow fiom F,EF(2),I,BI,AB,A,BE,H. Flow noticeably siower fiom BF arm of paths. Flow more sporadic from BF arrn; still a healthy flow rate and variable drop size. Flow almost stopped, occasional drop nom B,I,AB. Just before gradient change, semi regular flow from IB@; variable size. Closely equivalent to gradient before flow on drainage leg in timing oniy. Drop sizes much bigger. Flow seems to have stopped nom areas listed above. Bubbling fiom 1,1z42; drops stopped. Bubbles forming very slowly, releasing very sporadically. Bubbling quickening at gradient change. Now fiom areas 7,8,5,6,1,3,4 and 6 bubbles dong 1-2 a m of fkcture.

Table C.9 - Data from run #9; 115 mm pool height under wetting conditions (February 18,1997).

Chrono CumuL PCE Pool Waterffow Lab Corn Gradient Real Time Time vol. Flow rate Height time TÏme temp #

tirne (min) (s) (min) (ml) (milmin) (mm) (min) (s) (min) (deg C )

0.00 50 30 50.50 1855 7t.43 115 23.0

Chrono Cumul. PCE Pool Waterflow Lab Comrn. Gradient Real Time Time vol. Wow rate Height time Tirne temp #

time (min) (s) (min) (mi) (mumin) (mm) (min) (s) (min) (deg C) 0.40 0:30 330 4320 116 22.5 49

0:38 338 4320 116 23.0 50 1 :25 385 4320 116 22.5 51

0.45 1:30 390 4320 116 22.5 52 2:26 446 4320 116 22.5 53

0.50 2:30 450 4320 116 22.5 2:31 45 1 4320 116 13 57.64 13.96 22.5 2:46 466 4320 116 13 35.41 13.59 22.5 54

0.55 3:Oû 480 4320 116 22.5 3:02 482 4320 116 10 30.27 10.50 22.5 55 3:13 493 4320 116 10 20.04 10.33 22.5

0.60 230 510 4320 116 22.5 3:31 51 t 4320 116 8 36.73 8.61 22.5 3:41 521 4320 116 8 32.42 8.54 22.5 3 5 1 531 4320 116 8 29.3 8.49 22.5 4:OO 540 4320 116 8 17.97 8.30 22.5 4:lO 550 4320 116 8 21.24 8.35 22.5 4:19 559 4320 116 22.5 56

Run #81#9 - Cumulative PCE volume vs. time DrainageMietüng - 115 mm pool height

Figure CS - Run #SM9 data; 115 mm pool height under drainageiwetting conditions.

Run #9 - Comments February 18, 1997

Wetting; 0.1 15 m pool height.

Water overfiow at 157 mm. i=O. 10, flow Çom F,EF(2),I,BI,AB,A,BE7H. Flow noticeably slower f?om BF a m of paths. Flow more sporadic fiom BF arm; still a healthy flow rate and variable drop size. Flow aimost stopped, occasional drop fiom B,I,AB. Just before gradient change, semi regular flow from I,B,AB; variable size. Closely equivalent to gradient before flow on drainage leg in timing only. Drop sizes much bigger. Flow seems to have stopped fiom areas listed above. Bubbling fkom 1,192; drops stopped. Bubbles forming very slowly, releasing very sporadically. Bubbling quickening at gradient change. Now fiom areas 7,8,5,6,1,3,4 and 6 bubbles along 1-2 arm of hcture. Water overfiow at 16 1 mm. Same pattern of bubbles. Bubbling rate increased with gradient change. Changing water source carboy. Same pattem emerging as other nins - bubbles at primary flow paths. Bubbles distinct along fracture trace. Bubbling rate increased with gradient change. Drop. Water overfiow at 162 mm. Bubbling pattern remained consistent. Rate faster but not as fast as on drainage; compare Q's. .

Valve 2 closed, valve 7 cIosed, valve 1 closed. Valve 3 open to drain, upper reservoir water at 15 mm. Valve 3 closed, valve 2 open to raise level and drain remaining 21 3 mm in bottom reservoir. (Note: had 1 16 mm in upper reservoir and 244 mm in bottom reservoir. Now, 213 mm ( = m l ) in bottom. Raised H . 6 to i=0.9. Water level at 80 mm, valve 2 closed, valve 3 open, water in upper resewoir to 20 mm, PCE in bottom to 142 m. Valve 3 closed. Water level at 60 mm, valve 2 closed, valve 3 open, water in upper reservoir to 17 mm, PCE in bottom to 39 mm. Valve 3 closed. Water level at 40 mm, valve 2 closed, valve 3 open, water in upper reservoir to 26 mm, PCE in bottom to O mm. Valve 3 closed. Run terminated valve 2 open (water in at i = 0.9), valve 3 closed.

Table C.10 - Data from run #IO; 85 mm pool height in sand under drainage conditions (April8, 1997).

Chrono Cumul. PCE Pool Waterfiow Lab Comi Gradient Real fime Time vol. Flow rate Height time Eme temp #

time (min) (s) (min) (ml) (mumin) (mm) (min) (s) (min) (deg C)

0.60 1254 -1 056 O O 19.5 13:07 -1 043 O 40 20.0 13:39 -101 1 O 72 20.0 13:58 -992 O 80 20.0 14AO -980 O 88 4 28.60 4.48 20.0 14:17 -973 O 88 4 28.67 4.48 20.0 t4:29 -96 1 O 88 4 29.31 4.49 20.0 l4:36 -956 O 88 4 29.50 4.49 20.0 1458 -934 O 88 4 31.56 4.53 20.0 1510 -920 O 88 20.0 1518 -912 O 88 4 32.27 4.54 20.0 15:30 -900 O 88 20.0 16:07 -863 O 88 4 40.19 4.67 20.0 16:13 - 8 s O 88 4 39.77 4-66 20.0 16:20 -850 O 88 4 39.10 4.65 20.0

0.55 16:30 -840 O 88 20.0 16:45 -825 O 88 5 3.55 5-06 20.0 17:Ol -809 O 88 20.0 17:08 -802 O 88 5 4.88 5.08 20.5 1 7:15 -795 O 88 5 3.84 5 . 20.5

0.50 17:30 -780 O 88 20.0 17:43 -767 O 88 20.5 1753 -757 O 88 5 39.34 5.66 21.0 18:01 -749 O 88 5 39.36 5.66 21.0 18:09 -741 O 88 5 40.53 5.68 21.0 1 822 -728 O 88 5 39.92 5.67 21.0

0.45 18:30 -720 O 88 20.5 18:34 -71 6 O 88 6 28.84 6.48 20.5 18:44 -706 O 88 6 29.09 6.48 20.0 19:15 675 O 88 6 46.10 6 . n 20.0 19:24 666 O 88 6 47.96 6.80 20.0 19:33 -657 O 88 6 48.35 6.81 20.0 19:42 648 O 88 6 47.89 6.80 20.0

0.40 2O:OO -630 O 88 20.0 20:06 -624 O 88 8 2.50 8.04 20.0 20: 16 -61 4 O 88 8 3.30 8.06 20.0 2050 -580 O 86 8 5.00 8.08 19.0 2059 -571 O 86 8 4.97 8.08 19.5 21 :O8 -562 O 86 8 5.07 8.08 19.0 21:17 -553 O 86 8 5.81 8.10 19.0

0.35 21:30 -540 O 86 19.5 21 :36 -534 O 86 9 42.00 9.70 19.5 21% -51 6 O 86 9 44.45 9.74 19.5 2205 -505 O 86 9 46.58 9.78 19.5 2235 475 O 86 9 50.28 9.84 20.0 2247 463 O 86 9 51.46 9.86 20.0 23:01 -449 O 86 10 3.21 10.05 19.5 23:35 4 1 5 O 86 10 7.43 10.12 20.0 0:10 -380 O 86 10 10.05 10.17 20.0 0:39 -35 1 O 86 10 12.95 10.22 19.5

Chmno Cumul. PCE Pool Water flow Lab Comm. Gradient Real ïime Time vol. Flow rate Height time fime temp #

time (min) (s) (min) (ml) (rnllmin) (mm) (min) (s) (min) (de9 C ) 1:06 -324 O 10.64 10.18 20.0 1 C

Chrono Cumul. PCE Pool Waterfiow Lab Cornm. Gradient Real Time Time vol. Flow rate Height time Time temp #

time (min) (s) (min) (ml) (mumin) (mm) (min) (s) (min) (deg C)

51 9 51.15 1300 60.00 86 21 .O 5 1 44 51.73 1365 111.43 86 21 .O 52 18 52.30 1400 61.76 86 21 .O 52 52 52.87 1450 88.24 86 21 .O 53 3 53.05 1470 109.09 86 21 .O 53 35 53.58 1500 56.25 86 21 .O 54 2 54.03 1560 133.33 86 21 .O

Table C . l l - Data from run #LI; 85 mm pool height in sand under wetting conditions (Aprii 8,1997).

Chrono Cumul. PCE Pool Water flow Lab Corn Sradjent Real Time Time vol. Fiow rate Heqht time Time temp #

time (min) (s) (min) (mi) (mumin) (mm) (min) (s) (min) (deg C) 0.00 54 39 54.65 1600 m.86 86 21 .O

Chrono Cumul. PCE Pool Waterflow Lab Cornm. ;radient Real Tirne Time vol. Flow rate Height tirne Tirne temp #

tirne (min) (s) (min) (ml) (mVmin) (mm) (min) (s) (min) (deg C) 77 59 77.98 3240 75.00 86 21 -5

Run #?OI#l? - Cumulative PCE volume vs. time DrainageMletting - 85 mm pool height in sand

-1100 -1000 -800 80a -700 -640 500 400 -300 -200 -100 O 100 200 300 (00

Tlme (minutes)

+Dranape (Run #la)

+ Wstting (Run ut 1)

Figure C.6 - Run #10/#11 data; 85 mm pool height in sand under drainagelwetting conditions.

Run #10/#11- Comments ApriI 8, 1997

DrainageIWetting; 0.088 m pool height in SAND.

Pump off most of the time. Pool at 80 mm height but 2 areas (centre tongue and side tongue at 88 mm) are higher. Water level at 163 mm. Pool evening out dong 86-88 mm height. Photo taken of apparatus. Carboy (w-wastewater) starting to overfill. Note: flow rate decreasing (flow times increasing) despite valve 6 opened before reading. Upon examining last drainage run, flow times followed similar patterns. Will leave gradient at 0.6 until level rate seen. Perhaps examine Chown sand nui

data for dues. Water level in CHWT dropped -1" below overflow before being caught. Steady state reached at i4.45; wilI change to i 4 . 4 at 20:OO. No drops yet. Arrived just as water level at 500 ml - flow rate may be off slightly. Photo. Pool has appeared to level out. The top outline is smoother and the highest point (which was at - 90 mm) is now at 86 mm. Compare photo taken at '9' with that taken at '4'. Provides explmation for decrease flow rate (i.e. PCE moving into h c ture) . No drops. PCE pump on. Pool height debatable (highest at 88 mm). Measured 400 ml due to tirne restrictions. PCE pump on. No drops. Level in upper reservoir looking lower (?), on average. Before start of this flow test, waste carboy overfilied. (Flow test for 200 ml). PCE pump on. FIow test for 400 ml. FIow test for 250 ml. Also 250 ml. -30 s - 60 s to start. Large bubbles and variable. From H,AB,B,BI - four streams. Largest nom B up to 5 mm diameter also <1 mm diameter fiom same exit; others 1-2 mm. From C (large 4-5 mm). From BE, and fiom A, 1 (visibly faster 80w). More volume fiom B. Flow £rom CJ. From F, EF. Tank slipped below i=û about 5 mm for 5 sec. Pool hi&. Flow fiom H,A,AEl,B,C,I,BE,CJ. CHWT vibrated - changing overflow carboy. No water overfiow noticed.

Paths to 4, then 3, then 2, now only at A. Plus occasional drops at H. BE, B. Water overflow - slow but restarted. Drop. Drop afier 30 S. Drop. No drops. Pool moving upward since PCE flow stopped. Water overflowing at gradient change (more noticeable). Photos (3); whole, upper, sand. Volume for flow test 300 ml. PCE in sand pack being mobilized upward - can see pores being invaded above PCE Ievel d e r gradient change. No PCE drops. Run terminated.

Table C.12 - Data from run #12; 85 mm pool height in sand under drainage :onditions with 2% Witeonol solution as aqueous phase (July 9,1997).

Chrono Cumul. PCE Pool Water flow Lab Cornm. Gradient Real Tirne Tirne vol. Flow rate Height time Time temp #

time (min) (s) (min) (mi) (mumin) (mm) (min) (s) (min) (deg C)

24

Chrono Cumul. PCE Pool Water flaw Lab Comrn. Gradient Real Tirne Time vol. Flow rate Height time Time temp #

tirne (min) (s) (min) (ml) (mumin) (mm) (min) (s) (min) (deg C )

8 13.57 8.226 70 15.39 86

Table C.13 - Data from ru^ #13; 85 mm pool height in sand under wetting conditions with 2% Witconol solution as aqueous phase (July 9,1997).

Chrono Cumul. PCE Pool Water flow Lab Comm. Gradient Real Time Time vat. Flow rate Height time Time temp #

tirne (min) (s) (min) (ml) (mumin) (mm) (min) (4 (min) (deg C)

0.00 4 1 55 41.92 1810 43.18 82 23.0

Chrono Cumul- PCE Pool Water flaw i a b Comm. Gradient Real Tirne Tirne vol. Flow rate Height time Tirne temp #

time (min) (s) (min) (mi) (milmin) (mm) (min) (s) (min) (deg C ) 1956 145 50 145.83 4000 27.43 90 23.0 37

Ftun #121#13 - Cumulative PCE volume vs. tirne DrainageMIetting - 85 mm pool height in sand

Interfacial tension = 7.5 dyneslcm

400 -300 -Ma -100 O 100 ZM1 S00

lime (minutes)

Figure C.7 - Run #12/#13 data; 85 mm pool height in sand under drainagelwetting conditions for 2% polyoxyethylene sorbitan ester solution.

Run #12/#13 - Comments July 9, 1997

Drainage/Wening; 0.085 m pool height in sand; 2% surfactant solution added.

Turned off valve 2, valve 3 on to exmaine residual characteristics before nui

commences. Very small amount of residual in h t u r e network. Micron size diameter droplets out of A, 1, AB. Millimeter drop size out of J (back of fracture network is last to drain)

PCE tankat 22 mm. T m e d water pump off, draining CHWT to bottom. With 1" water lefi in CHWT, valve 2 closed, surfactant purnped in. Note 4 1 in bottom reservoir will mix with surfactant added. Opening valve 2. 1 2: 13 surfactant in and d g . Drops on bottom reservoir angled plates are rolling down to outlet. Surfactant corning in is swirling into bottom of reservoir; 'clear' water seems to be stratified about valve 2 inlet. More drops rolling down; profile ai5ected by gravity. Opened valve 1, valve 7. Water overflow at 164 mm. 12:29 Still no pool showing in upper reservoir.

Can't see any ïncrease in Snw in upper reservoir. Lower reservoir d l 1 looks 'stratified' .

12:35 Pool appearing. Bottom reservoir now yellow in appearance; drops on stainless steel cleared off somewhat. Worried about surfactant supply - pool at 60 mm, 63 mm. Use this height for cornparison with previous run - no, must be in sand. Going to 85 mm. water] Flow surprisingly fast considering pool in. Photos (see record on p. 68 opposite). No change in bottom of h c t u r e network fiom when surfactant added, except one drop at J which was hanging did drop down. Other hanging drop at H is small and d l 1 hanging. Liquid out fiom flow tests is clear and slightly sudsy but not significantly. Water overflow at 163 rnm. Top reservoir liquid (above sand pack) looks clear. DNAPL tank at 38 mm. In bottom reservoir, evidence of swirling surfactant - it is very slow and nothing like first introduction of surfactant to bottom reservoir but still see surfactant solution 'phase' moving.

Sporadic drops roll down dong bottom stainless steel plate. Have been watching to ensure that they or igbte fkom plate surface and did not drop 6om hc ture network. Missed reading. 13:2 1 Drop nom fracture. 35 s second drop (BE) Overflow fiom missed reading felt soapy on gloves. 13:23 Drops fiom EF (a couple) - more (4-5) also fiom EF at 12:25. 13:29 S m d &op and another &op. NB: From previous nui, eight wetted drops on back stainless steel wall of apparatus at 235 mm height. Since Surfactant addition, one drop has appeared to "dry up" leaving dye evidencekesidue. So far, drops seem were fiom areas without PCE evident £im bottom. Also nom places that are usually last to start flowing. Drop fiom AB, about 1 mm diameter; notice flow rate gening slower very gradually . Will measure out more surfactant for wetting am. Currently 1352, will stop vigil for drops and corne back to measure water flow rate. Source carboy nearly empty. 1355 drop fiom BE, changing source carboy.

130.03 g in 1 L flask 252.04 g in 2 L nask {MWng at 14:08)

14: 1 1 watching for drops. Pool seems to have flattened by perhaps 1 mm. Pump on about 1 minute, pool to 90 mm Flow rate jurnp. Stu moving stuff around lab. Haven't seen many drops emanating, no rate increase or evidence of nich; will go to i=OS at 14:30. Pool Iooks flatter. Flow rate about 3mYmin faster than run 13 - okay. Stopping vigil 14:39 for food, back in ten. Two drops fiom B area (just got back), two drops 30 s later nom F. 1459 3 drops at F, 1 at J 15:07 &op fiom AB, 2 drops at F, 30 s later, drop 45 s later fkom J. Drop fiom B (15:30) Will leave at this gradient longer - been womed about surfactant supply. Last reading for 0.5 gradient indicated aqueous phase slowing. Drop from EF (15:33). 1 5:36 Drop nom BE Tumed pump on siowiy and ievel to 96 mm in about 2 minutes. Saturation (nw) doesn't look too much different from run 13. Drops fiom G or F (16:27) - about three 1 mm diameter. Height of PCE down to 9 1 mm 1s pool movhg down through hcture? Or is lower hydraulic gradient causing less uplift through sand? Fixed recirculation line fiom leaking. Water overflow at I 6 1 mm. Changed gradient, nothing yet. Flow afler 30 s fiom 1, then AB,A,H,C,B. About 1 to 2 mm diameter drops. Flow after 3.5 minutes fiom BE,EF,F,CJ Nothing at .J after 6:45

1.BA.H bulk of flow (about 7 exit points), FB, less flow (dong FB, about 6 exit points) More flow fÏom same paths. BIobs fiom CJ moving toward J Blobs bigger by three or four times and more dense. Flow slower; just as 0.2 start; exact pattern reverse. Drops from HAPFB,B3ED Difficult to read scale; Ievel increasing by small amount since cross sectional area so much bigger. Flow fiom H,A,AB,B,BI,BE,EF (about 1-2 mm diameter) flow Iess dense. FIowing fiom same paths, more sparse. Turned pump up too fast. Only drops fiom A-,B,BE but visibly slowing as 1 write. Still dropping but not flowing fiom A,B,AB. 90 mm. Pool visibly moving upward in sand pack. Drop fiom J,EF,B (several fÏom EF). Very Pool up to 93 mm. Drop. Taking flow rate. 20: 10 Drop.

Water overflow at 262 mm. Pool at

s m d drops about 1 mm diameter.

20:25 Two, less than 1 mm diameter drops fiom B. 20:45 Drop, &op, &op, drop. About 1 mm fiom A- 20:48 Drop, drop.. . still fd ing but not a flow. Surfactant source running out Didn't notice drops before water test started. Note corresponding time to when drops occurred at i=0.6, i=0.5 in drainage arm. Most when flow tests going. Flow rate changing (decreasing) but ninning out of surfactant. Drop, drop fiom BE. Haven't seen drops at this gradient. 2 1 :23 Drop from B (1, < 1 mm dia.)

Drop fiom A 30 sec Iater same size. Water overflow at 163 mm. 2 1 :49 Drops from EF Valve 2 off. Run over. (Surfactant ran out). Valves 7 and 1 off. Valve 3 opened to drain and fine 'spray' of dnapl out, alrnost looks like rock d u t coming out, macroemulsion? Drained to 21 8 mm in lower reservoir; tumed on valve 2 Residual in sand pack looks much higher than previous sand nin without surfactant; 5 mm Iayer of very fine macroemulsion on dnapl pool in bottom

Table C.14 - Data from run #14; 85 mm pool beight under drainage conditions with 12% WitconoVethanol solutions as aqueous (August 16,1997).

Chrono Cumul. PCE Pool Waterflow Flow Lab Comm Gradient Real Time Tirne vol. Flow rate Height time Time rate temp #

time (min) (s) (min) (mi) (mumin) (mm) (min) (s) (min) (mumin) (deg C) 1 254 -366 n 24

Chrono Cumul. PCE Pool Waterffow FIow Lab Comrn. Gradient Real Time fime vol. Flow rate Height time Time rate temp #

time (min) (s) (min) (ml) (mumin) (mm) (min) (s) (min) (milmin) (deg C) 0.10 16 58.24 16.97 650 88 24.5

17 3057 17.51 700 86 24.5 18 49.49 18.82 780 86 24.5 19 20.94 19.35 850 86 24.5 19 4 6 . 9 19.78 900 86 24.5 20 16.34 20.27 950 86 24.5 20 47.67 20.79 1000 86 24.5 21 38.47 21.64 1100 86 24.5 22 31.89 22.53 1200 86 24.5 23 3.65 23-06 1270 06 24.5 23 22.54 23.38 1300 86 24.5 23 46.62 23.78 1360 86 24.5 24 9.25 24.15 1400 86 24.5

0.00 24 20.29 24.34 1430 85 24.5 24 40.14 24.67 1470 83 24.5 25 10.55 25.18 1580 85 24.5 25 36.34 25.61 1600 85 24.5 25 53.3 25.89 1650 85 24.5 26 11.09 26.18 1695 85 24.5 26 29.39 26.49 1740 85 24.5 26 38.04 26.63 1760 85 24.5 27 6.14 27.1 1800 85 24.5 27 14.74 27.25 1855 85 24.5

Table C.15 - Data from run #15; 85 mm under wetting conditions with 12% Witconoi/ethanol solution as aqueons solution (August 17, 1997).

Chrono Cumul. PCE Pool Waterflow Lab Comm. Gradient Real Tïme Time vol. Fiow rate Height time Erne temp #

time (min) (s) (min) (mi) (mumin) (mm) (min) (s) (min) (deg C) 0.00 27 3221 27.537 1900 85 24.5

, Chrono Cumul. PCE Pool Water flow Lab Cornm.

i Gradient Real Time T t vol, Flow rate Height time Time temp # time (min) (s) (min) (mi) (mumin) (mm) (min) (s) (min) (deg C) 21 :34 105 9 48.64 9.8107 24.5 21 57 104 24.5 36 2202 104 9 13.69 9.2282 24.5 37 2234 1 03 24.5 38 2239 105 5 52.3 5.8717 24.5 2255 106 24.5 39 23:15 104 24.5 40 23:21 104 5 34-41 5.5735 24.5 23:29 104 5 33.85 5.5642 24.5 2334 104 24.5 4 1 23:40 104 24.5 42

Run #141#15 - Cumuiative PCE volume vs. tirne DrainageMiletting - 85 mm pool height in sand

Interfacial tension = 5 dyneslcm

+Drainage (Run #14)

-+ Wetüng (Run t l 5)

Time (minutes)

Figure C.8 - Run #14/#15 data; 85 mm pool height in sand under drainage/wetting conditions with 12% surfactanVethanol solution.

Run #14/#15 - Comments August 16,1997

DrainageNetting; 0.085 rn pool height in sand; cosolvent solution added.

Filling CHWT with ethanoYsurfactant mixture. 13 : 16 Solution in and going up to hcture face, i.e. not mixing mid-level like pure surfactant was. Stream going onto area D-G. No visible change in residual appearance. Stratified at 296 mm in bottom reservoir. 13:20 Gradient established, opening valve 7, valve 1 (decided to wait until 13 :30). Stratified at 275 mm in bottom reservoir. Valve 7, valve 1 open; taking water reading . Pool filling 1 3 :3 1 at 3 5 mm. Missed reading, small spill of soluble waste at graduated cylinder. Taking another flow reading. Stratified at 271 mm. Pool at 60 mm steady. Flow slower with pool in. Stratified at 268 mm. Photo. Highest fingers in pool at 87 mm. Stratified at 267 mm (where bottom of valve 2 meets apparatus side wall). Feel dizzy . . . getting air. Flow tirne faster . . . surfactaat/ethanol solution still visibly swirling into bottom, stratifïed at 266 mm. Still feel cüzzy - Shi doesn't smell anythmg - 1 think it is the ethanoVPCE smell. Stratified at 264 mm. Pool looks slightly lower. Helium bubbling through second batch. Pump was on briefly but level went to 89 mm. Higher rate probably due to 2 mm extra height. ' Water' above sand pack started out slightly cloudy, now clearer. Fluid out in flow tests is not sudsy (compared to run 15). Air bubbles through hose into CHWT fiom source carboy - source out of solution. Changed source carboy - will mix up third batch witconoi just in case. Witconol lot numbers will be different if third batch used. Will go to I=0.5 at 15:30. Water overfiow at 162 mm. Streaming out of valve 2 not apparent, still stratified but upper section more mixed than before. Bottom fiacture face is ciean. NB: Witconol - mWng fiom second shipment

2 L flask 38 1.50 g; zeroed; 256.50 g 1 L flask 254.2 1 g; zeroed; 123.64 g Totd 380.14 g

Tumed pump on for too long, at 92 mm height. Pool height decreasing, seems to be on t h e scale of gradient change. Suspect PCE is rnoving downward through fracture network. Water overflow is at 16 1 -5 mm Noticed that there is a bright red drop in front-ish bottom corner that may have corne through fracture nehvork without my noticing. It is -2mm diameter.

Stratification at 163 mm but fiom 163 to 1 78 mm there is a rehctive index transition zone. Power source or something - same crackle of still, oven, lights (power surge?). Pool hasn't changed height; white-ish residue present near top. Photo. Flow fiom 1, then H, B-A, Ba, and from E, BE, EF. Interface of water/solution dishirbed and mixing apparent as drops f d through. Flow fiom F. More dong E, F. Hard to maintain pool height. Flow fÎom J &ter gradient change. 40 min, 9 s: blobs smaller Flow as it was at 0.2 on way down. Macroemulsion in sand. Turned on valve 6 for water reading, drïpping steadily but waterJsolution back into head tank fiom bottom reservoir. Pump on too long. Flow picked up because of height increase. Pump on again, quick a l . Miky 'water' in top reservoir - probably macroemulsion? Flow (drops) increase in kquency and location. Flow fiom BE,B,A,BA,H,I. -1 mm diameter average to 2 mm, also fkom F, E, smaller, sporadic - not "flow". Difncult to tell pool height in sand. Water dripping to almost 200 ml fiom comment 25, about 20 minutes. Pump on then off. Missed, pump Ieft on and height at 95 mm, almost 96 mm. Mobilizing up because of higher upward gradient? Water dripping more quickly. Noticable miiky emulsion in top reservoir. Despite higher pool height, decrease number of flow paths, where PCE coming out, did not iricrease. Pump has been off but pool height increasing. Almost at 100 mm. Very milky liquid coming off top of sand. Flow dl by ceased; AB, A, H flowing little. 500 ml filled from 72 min 16 sec entry, about 40 minutes. Water overflow at 162 mm. Will take water rate. Photo of 100 mm pool with 18 mm sand showing and about 15 mm (very cloudy) layer and milky top iayer to water overflow. Water less than 27 minutes. No drops out. Pool visibly moving up through sand at pore scale. Drops nom B. Stratification in top cloud not apparent anymore. Photo. 2 1 :O6 Drop.. . drop.. . &op. About 1 mm diameter, every 3 0 to 60 s then stopped. Pool at 105 mm; has not increased after gradient change. Sporadic drops fiom fiacture network. Pool more even, about 105 mm at highest (pool more levei); white rnacroemulsion more visible around sand grains than before.

36 Pool seerns to be 104 mm but no residual can be seen above.

@reps fiom BE) Noticing swirling into bottom reservoir of nirfactant/ethanol. NB: at gradient 0.3 to 0.0 to 0.3,0.4, solution going back into CHWT fiom carboy. Carboy raised volume until gradient of 0.4 on wetting a m was reached. Drops nom F,B. Musing that surfactant/ethanol entering into water layer because of stratification. At 10:30, wiU change to 0.6 gradient. Drops out of BA. Worried about surf/eth solution supply. Water ovexflow at 163 mm, pool moving up (visible on pore scale). Drops at 10:38 fiom AB Drop. Stratification becoming evident in aqueous phase (in bottom reservoir) Drops from E, EF - where sUrfactant/ethanol streaming into reservoir - are these comected? Drop fiom BE at 2258. Stratified at 27 1 mm but inclines upward to the right side of appantus. (Diagram in lab book) Pool seems to have flattened slightly. The 106 mm measurement previous to this one was highest finger - the rest of the pool did not follow. Taking photo of macroemulsion (2). One of upper reservoir, one on grain scale. Running out of solution. Flow rate seems to be increasing slightly, surqeth aimost out (about 2" in 19 L carboy). Run terminated, valve 2 off (flow started hedia te ly) . Valve 1 off, valve 7 off. Pool dropped. Photo. Valve 5 closed (water overflow at 16 1 mm). More flow, mixing evident of s d e t h and water. Will drain lower reservoir (tuming valve 5 on).

Could see droplet flow through sand against glass. Chaonels against g las in pores where individual drops were flowing fiom suction applied from below fracture network. Took 2 photos to show large scale 'channels'. Will take closer c hot o.

Appendix D Linear Regression Data

Table D.1- Linear regression data for nin #1.

Table D.2 - Lkear regression data for runs #2 and #3.

Table D3 - Linear regression data for runs #4 and #5.

Table D.4 - Linear regression data for runs #6 and #7.

Table D.5 - Linear regression data for m s #8 and #9.

Table D.6 - Linear regression data for ruus #10 and #Il.

Table D.7 - Linear regression data for mns #12 and #13.

Table D.8 - Linear regression data for mns #14 and #15.

Appendix E Fracture Netwcrk Map

T e - / . < C V V

Figure E.1- Fracture Trace Map