Potential Utilization of Fgd Gypsum for Reclamation Of

POTENTIAL UTILIZATION OF FGD GYPSUM FOR RECLAMATION OF

ABANDONED HIGHWALLS

THESIS

Presented in Partial Fulfillment of the Requirements for

the Degree of Masters of Science in the

Graduate School of the Ohio State University

Deepa Modi

Graduate Program in Civil Engineering

The Ohio State University

2010

Thesis Committee

Dr. William E. Wolfe, Advisor

Dr. Tarunjit S. Butalia, Co-Advisor

Dr. Fabian H. Tan

Deepa Modi

2010

Abstract

In order to reduce air pollution resulting from the combustion of coal in electric utility boilers, utilities that operate coal-fired power plants have installed air pollution control technologies. While airborne pollution has been significantly curtailed, these methodologies have significantly increased the amount of solid byproducts generated, most of which are currently landfilled.

In the Appalachian region of the US, a large number of abandoned coal mines exist, many with dangerous highwalls and pits. These abandoned highwalls pose a safety risk and many are sources of acid mine drainage that can compromise the quality of the ground water and nearby streams.

In this thesis, the above two issues are addressed and the utilization of coal combustion by-products in mine reclamation work has been studied. This study is focused on the use of FGD (Flue Gas Desulfurization) gypsum in the reclamation of abandoned coal mine highwalls.

The main objective of this research is to investigate the potential use of FGD gypsum (in the combination with fly ash and lime) as a backfill material for reclaiming abandoned highwalls. FGD gypsum and a mixture of FGD gypsum, fly ash, and lime are studied as a potential highwall backfill material. Several laboratory tests (e.g. compaction, strength, permeability, and solubility) are performed. The substitution of

ii FGD gypsum with fly ash did not appreciably change the permeability or strength of the

FGD gypsum. However, the addition of lime to the mixture of FGD gypsum and fly ash

reduced the permeability and increased the strength by an order of magnitude. Solubility

of the FGD gypsum mixes studied was found to be low.

In order to check the stability of a reclaimed highwall backfill, the factor of safety

was evaluated using a commercial analyses program for a demonstration site close to the

Conesville power plant. The slope stability analyses indicated that FGD gypsum or a mixture of FGD gypsum and fly ash gives a factor of safety more than 1.5.

iii

Dedication

Dedicated to my family

Acknowledgements

I would like express my heartiest gratitude to my advisors, Prof. William E. Wolfe

and Dr. Tarunjit S. Butalia, for their strong motivation, perpetual and methodical

guidance, and idea oriented discussions and constant encouragement to pursue my

master’s studies. Without their able guidance, this work would not have materialized.

Their encouragement and suggestions made the research work interesting and

challenging. Knowledge gained from their expertise and experience has made my

master’s program the most fruitful years of my life academically.

I would like to acknowledge my thesis committee member, Prof. Fabian H. Tan, for his time and suggestions. Special thanks to James Howdyshell for helping me out in the laboratory; without his help it would have been difficult to complete this work.

I am indebted to my parents and the elders of my family for their support and blessings. Their blessings were the most important factor leading to the completion of this work.

Vita

April 2004……………..……………………………B.Sc. Engineering (Civil)

National Institute of Technology,

Patna, India

July 2007……………..…………………………..…M. Tech. (Civil/Geotechnical Eng.)

Indian Institute of Technology,

Bombay, India

2008 - Present………..……………………………..Graduate Research Fellow

Civil Engineering Department

The Ohio State University

Publications

1. Deepankar Choudhury and Deepa Modi (2008); “Displacement-based stability

analysis of slopes under seismic conditions”, Geotechnical Earthquake Engineering

and Soil Dynamics IV (GEESD-2008), May 18 - 22, 2008, Sacramento, California

2. Deepa Modi, Deepankar Choudhury and K. S. Subba Rao (2007); "Simplified

analysis of seismic slope stability by using pseudo-static approach", Proc. of National

Conference on Foundations and Retaining Structures (NCFRS-2007), May 23-24,

2007, IIT Roorkee, India, Vol. 1, pp. 114-117

Fields of Study

Major Field: Civil Engineering

vii

Table of Contents

Abstract……………………………………………………………………..……………..ii

Dedication………………………………………………………….………….……….…iv

Acknowledgements……………………………………………….………….…………....v

Vita………………………………………………………………..………………………vi

List of Tables……….…………………………………………………………………….xi

List of Figures…………………………………………………………...……………..xviii

CHAPTER 1: INTRODUCTION

1.1. Background……………………………………………………………...………..1

1.2. Research Objective………………………..……………………………………...1

CHAPTER 2: BACKGROUND INFORMATION 2.1 Introduction……………………………………………………………………...... 3 2.2 Production and Utilization of CCBs……………………………………………....3 2.3 FGD Material Production Technologies……….…………………………..……...6

2.4 Physical and Chemical Properties of FGD Gypsum and Natural

Gypsum………………………………………………………………..….……….7

2.5 Issues Related to Abandoned Mines and Reclamation……………………………9

2.6 Mine Reclamation in Ohio using FGD Gypsum………………………………...10

2.7 Summary…………………………………………………………………………13

viii

CHAPTER 3: LABORATORY TESTS & RESULTS

3.1 Introduction………………………………………………………………………14

3.2 Laboratory Tests……………………………………………………………….....15

3.3 Laboratory Tests Samples and Results…………………………………………...16

3.3.1 Laboratory Tests Samples………………………………………………..17

3.3.2 Laboratory Tests Results on Cardinal FGD Gypsum Samples…………..17

3.3.2.1 Compaction Test……………………………………………………..17

3.3.2.2 Strength Test………………………………………………………....19

3.3.2.3 Permeability Test…………………………………………………...... 25

3.3.2.4 Solubility Test……………………………………………………...... 30

3.3.3 Laboratory Tests Results on Conesville FGD Gypsum………..………...35

3.3.3.1 Compaction Test……………………………………………………..35

3.3.3.2 Strength Test…………………………………………………………37

3.3.3.3 Permeability Test………………………………………………….....38

3.3.3.4 Solubility Test………………………………………………………..39

3.4 Results and Discussion…………………………………………………………..40

CHAPTER 4: SLOPE STABILITY ANALYSIS

4.1 Introduction………………………………………………………………………45

4.2 About the SLOPE/W Software…………………………………………..………46

4.3 Materials for Backfill and Their Properties…….…………………………….....46

4.4 Slope Stability Analyses and Results on the Four Backfill Materials…...…...... 49

ix 4.4.1 Conesville FGD gypsum as Backfill Material………………….………..51

4.4.2 A Mixture of Cardinal FGD Gypsum and Fly Ash as Backfill

Material...... 55

4.4.3 Cardinal FGD gypsum as Backfill Material……………………………..59

4.4.4 A Mixture of Stabilized FGD/ FA/FGD Gypsum as Backfill Material.....70

4.5 Results and Discussion…………………………………………………………..78

4.6 Summary…………………………………………………………………………79

CHAPTER 5: CONCLUSIONS

5.1 Summary…………………………………………………………………………82

5.2 Conclusions………………………………………………………………………83

5.3 Recommendation for Future Work………………………………………………85

List of References………………………………………………………………….….....86

Appendix A: Laboratory Test Data Sheets………………………………………………90

List of Tables

Table 2.1: Production and Use of Coal Combustion Byproducts in 2008 in USA [2]……5

Table 2.2: Physical Properties of FGD Gypsum versus Natural Gypsum [14, 18]……….8

Table 2.3: Chemical Properties of FGD Gypsum versus Natural Gypsum [14, 18]...... 8

Table 2.4: Production of FGD Material in Ohio by Five FGD Material Producing Power

Plants in the Ohio Coal Mining Region [26]...…………………………………..12

Table 3.1: Proportions of FGD Gypsum, Fly Ash and Lime Tested in

Laboratory………………………………………………………………………..15

Table 3.2: Details of the Samples made for Laboratory Tests …………………………..17

Table 3.3: Maximum Dry Unit Weight and Optimum Moisture Content for Cardinal FGD

Gypsum, Fly Ash, and Lime Mix Samples……………………….……………...18

Table 3.4: Unconfined Compressive Strength of Cardinal FGD Gypsum, Fly Ash, and

Lime Mix Samples Cured from 1 Day to 8.5 Months………………...... 22

Table 3.5: Permeability of Cardinal FGD Gypsum, Fly Ash, and Lime Mix Samples

Cured for 7, 28, 60, and 90 Days…………...…….…..………………………….29

Table 3.6: Percent Solid Collected from Effluent of Cardinal FGD Gypsum, Fly Ash, and

Lime Mix Samples Cured for 7, 28, 60, and 90 Days…………………………...34

Table 3.7: Optimum Moisture Content, Maximum Dry Density and Strength of Cardinal

FGD Gypsum Mix Samples Cured for Different Time Period …………..……...42

Table 3.8: Permeability and Percent Solids Collected in the Effluent of Cardinal FGD

Gypsum Mix Samples …………………………………………………………...43

Table 3.9: Compaction Test Results for FGD Gypsum and FGD Gypsum & Lime Mix

Samples (FGD Gypsum Obtained from Conesville Power Plant)…………….....44

Table 3.10: UCS, Permeability and Percent Solids Collected in the Effluent for FGD

Gypsum Obtained from Conesville Power Plant………………………………...44

Table 4.1: Material Properties used in Slope Stability Analyses...……………...….……48

Table 4.2: Factor of Safety of Slopes at the Five Sections using Conesville FGD Gypsum

as Backfill Material..…………………………………………………….……….52

Table 4.3: Factor of Safety of Slopes at Five Sections using a Mixture of Cardinal FGD

Gypsum and Fly Ash as Backfill Material….....…………………………………56

Table 4.4: Factor of Safety of Slopes at Five Sections using Cardinal FGD Gypsum as

Backfill Material ………………………………………………………….……..62

Table 4.5: Factor of Safety at Five Sections Obtained by using a Mixture of Stabilized

FGD Material, Fly Ash, and FGD Gypsum as Backfill Material………………..72

Table 4.6: Factors of Safety at Five Sections Obtained for Four Different Backfill

Materials…………………………………………………………………………81

Table A.1: 100% Cardinal FGD Gypsum Compaction Test Data……………………….92

Table A.2: 50% Cardinal FGD Gypsum and 50% Fly Ash Mix Sample Compaction Test

Data………………………………………………………………………………93

xii

Table A.3: 50% Cardinal FGD Gypsum, 50% Fly Ash, and 2% Lime Mix Sample

Compaction Test Data……………………………………………………………94

Table A.4: 50% Cardinal FGD Gypsum, 50% Fly Ash, and 4% Lime Mix Sample

Compaction Test Data……………………………………………………………95

Table A.5: Permeability Data Sheet for 100% Cardinal FGD Gypsum Sample Cured for 7

Days, 500 ml readings……………………………………………………………97

Table A.6: Permeability Data Sheet for 100% Cardinal FGD Gypsum Sample Cured for

28 Days, 500 ml readings………………………………………………………...98

Table A.7: Permeability Data Sheet for 100% Cardinal FGD Gypsum Sample Cured for

60 Days, 500 ml readings………………………………………………………...99

Table A.8: Permeability Data Sheet for 100% Cardinal FGD Gypsum Sample Cured for

90 Days, 500 ml readings……………………………………………………….100

Table A.9: Permeability Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix Sample

Cured for 7 Days, 500 ml readings…………………………………………… 101

Table A.10: Permeability Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix

Sample Cured for 28 Days, 500 ml readings…………………………………...102

Table A.11: Permeability Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix

Sample Cured for 60 Days, 500 ml readings…………………………………...103

Table A.12: Permeability Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix

Sample Cured for 90 Days, 500 ml readings…………………………………...104

xiii

Table A.13: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2% Lime

Mix Sample Cured for 7 Days, 500 ml readings……………………………….105

Table A.14: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2% Lime

Mix Sample Cured for 28 Days, 500 ml readings……………………………...106

Table A.15: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2% Lime

Mix Sample Cured for 60 Days, 500 ml readings……………………………...107

Table A.16: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2% Lime

Mix Sample Cured for 90 Days, 500 ml readings……………………………...108

Table A.17: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4% Lime

Mix Sample Cured for 7 Days, 500 ml readings………………………..……...109

Table A.18: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4% Lime

Mix Sample Cured for 28 Days, 500 ml readings……………………………...110

Table A.19: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4% Lime

Mix Sample Cured for 60 Days, 500 ml readings……………………….……...111

Table A.20: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4% Lime

Mix Sample Cured for 90 Days, 500 ml readings……………………….……...112

Table A.21: Solubility Data Sheet for 100% FGD Gypsum Sample Cured for 7

Days…………………………………………………………………………….114

Table A.22: Solubility Data Sheet for 100% FGD Gypsum Sample Cured for 28

Days…………………………………………………………………………….115

xiv

Table A.23: Solubility Data Sheet for 100% FGD Gypsum Sample Cured for 60

Days…………………………………………………………………………….116

Table A.24: Solubility Data Sheet for 100% FGD Gypsum Sample Cured for 90

Days…………………………………………………………………………….117

Table A.25: Solubility Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix Sample

Cured for 7 Days………………………………………………………………..118

Table A.26: Solubility Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix Sample

Cured for 28 Days………………………………………………………………119

Table A.27: Solubility Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix Sample

Cured for 60 Days………………………………………………………………120

Table A.28: Solubility Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix Sample

Cured for 90 Days………………………………………………………………121

Table A.29: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2% Lime

Mix Sample Cured for 7 Days………………………………………………….122

Table A.30: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2% Lime

Mix Sample Cured for 28 Days………………………………………………...123

Table A.31: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2% Lime

Mix Sample Cured for 60 Days………………………………………………...124

Table A.32: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2% Lime

Mix Sample Cured for 90 Days………………………………………………...125

Table A.33: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4% Lime

Mix Sample Cured for 7 Days……………………………………………….....126

Table A.34: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4% Lime

Mix Sample Cured for 28 Days………………………………………………...127

Table A.35: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4% Lime

Mix Sample Cured for 60 Days………………………………………………...128

Table A.36: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4% Lime

Mix Sample Cured for 90 Days………………………………………………...130

Table A.37: Pore Volume Calculation Data Sheet for 100% FGD Gypsum Sample Cured

for 7 Days………………………………………………...... 131

Table A.38: Pore Volume Calculation Data Sheet for 100% FGD Gypsum Sample Cured

for 28 Days……………………………………………………...... 132

Table A.39: Pore Volume Calculation Data Sheet for 100% FGD Gypsum Sample Cured

for 60 Days………………………………………………...... 133

Table A.40: Pore Volume Calculation Data Sheet for 100% FGD Gypsum Sample Cured

for 90 Days………………………………………………...... 134

Table A.41: Pore Volume Calculation Data Sheet for 50% FGD Gypsum and 50% Fly

Ash Mix Sample Cured for 7 Days……………………………………………..135

Table A.42: Pore Volume Calculation Data Sheet for 50% FGD Gypsum and 50% Fly

Ash Mix Sample Cured for 28 Days……………………………………………136

xvi

Table A.43: Pore Volume Calculation Data Sheet for 50% FGD Gypsum and 50% Fly

Ash Mix Sample Cured for 60 Days……………………………………………137

Table A.44: Pore Volume Calculation Data Sheet for 50% FGD Gypsum and 50% Fly

Ash Mix Sample Cured for 90 Days……………………………………………138

Table A.45: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly Ash,

and 2% Lime Mix Sample Cured for 7 Days…………………………………...139

Table A.46: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly Ash,

and 2% Lime Mix Sample Cured for 28 Days………………………………….140

Table A.47: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly Ash,

and 2% Lime Mix Sample Cured for 60 Days………………………………….141

Table A.48: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly Ash,

and 2% Lime Mix Sample Cured for 90 Days………………………………….142

Table A.49: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly Ash,

and 4% Lime Mix Sample Cured for 7 Days…………………………………...143

Table A.50: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly Ash,

and 4% Lime Mix Sample Cured for 28 Days………………………………….144

Table A.51: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly Ash,

and 4% Lime Mix Sample Cured for 60 Days………………………………….145

Table A.52: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly Ash,

and 4% Lime Mix Sample Cured for 90 Days………………………………….146

xvii

List of Figures

Figure 3.1: Compaction Test Results for Cardinal FGD Gypsum Mixes………………..18

Figure 3.2: Strength of Cardinal FGD Gypsum, Fly Ash, and Lime Mix Samples Cured of

7, 28, 60, and 90 Days………………………………………………..…………..21

Figure 3.3: Unconfined Compressive Strength of 100% Cardinal FGD Gypsum Samples

Cured for Six Different Time Periods ……...…………………………….……...23

Figure 3.4: Unconfined Compressive Strength of 50% Cardinal FGD Gypsum and 50%

Fly Ash Samples Cured for Five Different Time Periods..………………………23

Figure 3.5: Unconfined Compressive Strength of 50% Cardinal FGD Gypsum, 50% Fly

Ash, and 2% Lime Samples Cured for Five Different Time Periods…………….24

Figure 3.6: Unconfined Compressive Strength of 50% Cardinal FGD Gypsum, 50% Fly

Ash, and 4% Lime Samples Cured for Five Different Time Period …….……...24

Figure 3.7: Permeability versus Pore Volume of Effluent for 100% Cardinal FGD

Gypsum Samples Cured for 7, 28, 60, and 90 Days……………………………..26

Figure 3.8: Permeability versus Pore Volume of Effluent for 50% Cardinal FGD Gypsum

and 50% Fly Ash Samples Cured for 7, 28, 60, and 90 Days…………………....26

Figure 3.9: Permeability versus Pore Volume of Effluent for 50% Cardinal FGD Gypsum,

50% Fly Ash and 2% Lime Samples Cured for 7, 28, 60, and 90 Days……...... 27

xviii

Figure 3.10: Permeability versus Pore Volume of Effluent for 50% Cardinal FGD

Gypsum, 50% Fly Ash and 4% Lime Samples Cured for 7, 28, 60, and 90

Days……………………………………………………………………………...28

Figure 3.11: Percent Solid versus Pore Volume of Effluent for 100% Cardinal FGD

Gypsum Samples Cured for 7, 28, 60, and 90 Days……………………………..31

Figure 3.12: Percent Solid versus Pore Volume of Effluent for 50% Cardinal FGD

Gypsum and 50% Fly Ash Samples Cured for 7, 28, 60, and 90 Days.…………31

Figure 3.13: Percent Solid versus Pore Volume of Effluent for 50% Cardinal FGD

Gypsum, 50% Fly Ash, and 2% Lime Samples Cured for 7, 28, 60, and 90

Days………………………………………………………………………….…..32

Figure 3.14: Percent Solid Versus Pore Volume of Effluent for 50% Cardinal FGD

Gypsum, 50% Fly Ash, and 4% Lime Samples Cured for 7, 28, 60, and 90

Days……………………………………………………………………………...33

Figure 3.15: Compaction Test Results for Conesville FGD Gypsum……………………36

Figure 3.16: Unconfined Compressive Strength of Conesville FGD Gypsum Samples

Cured for Four Different Time ………..……………………………………..…..37

Figure 3.17: Unconfined Compressive Strength of Conesville and Cardinal FGD Gypsum

Samples Cured for 28 Days……………………………………………………...38

Figure 3.18: Permeability versus Pore Volume of Effluent for Conesville FGD Gypsum

Samples Cured for 7, 28, and 60 Days…………………………….…………...... 39

xix

Figure 3.19: Percent Solid versus Pore Volume of Effluent for Conesville FGD Gypsum

Samples Cured for 7, 28, and 60 Days…………………………….……………..40

Figure 4.1: Mine Reclamation Final Cap Grade Showing Sections 1-1, A-A, B-B, C-C,

D-D, and E-E [21]………………………………………………….…………….50

Figure 4.2: Stability of Slope at Section 1-1……………………………………………..51

Figure 4.3: Stability of Slope at Section A-A During/Immediately after the Construction

for Conesville FGD Gypsum as Backfill Material……...... 53

Figure 4.4: Stability of Slope at Section B-B During/Immediately after the Construction

for Conesville FGD Gypsum as Backfill Material……...... 53

Figure 4.5: Stability of Slope at Section C-C During/Immediately after the Construction

for Conesville FGD Gypsum as Backfill Material……...... 54

Figure 4.6: Stability of Slope at Section D-D During/Immediately after the Construction

for Conesville FGD Gypsum as Backfill Material……...... 54

Figure 4.7: Stability of Slope at Section E-E During/Immediately after the Construction

for Conesville FGD Gypsum as Backfill Material……...... 55

Figure 4.8: Stability of Slope at Section A-A During/Immediately after the Construction

for Cardinal FGD Gypsum and Fly Ash Mix as Backfill Material …………...... 57

Figure 4.9: Stability of Slope at Section B-B During/Immediately after the Construction

for Cardinal FGD Gypsum and Fly Ash Mix as Backfill Material………………57

Figure 4.10: Stability of Slope at Section C-C During/Immediately after the Construction

for Cardinal FGD Gypsum and Fly Ash Mix as Backfill Material..……………..58

Figure 4.11: Stability of Slope at Section D-D During/Immediately after the Construction

for Cardinal FGD Gypsum and Fly Ash Mix as Backfill Material…………...... 58

Figure 4.12: Stability of Slope at Section E-E During/Immediately after the Construction

for Cardinal FGD Gypsum and Fly Ash Mix as Backfill Material…..………...... 59

Figure 4.13: Stability of Slope at Section A-A During/Immediately after the Construction

using UCS Test Results……………...…………………………………...………63

Figure 4.14: Stability of Slope at Section B-B During/Immediately after the Construction

using UCS Test Results……………...…………………………………...………63

Figure 4.15: Stability of Slope at Section C-C During/Immediately after the Construction

Using UCS Test Results……………...…………………………………...….…..64

Figure 4.16: Stability of Slope at Section D-D During/Immediately after the Construction

Using UCS Test Results……………...…………………………………...….…..64

Figure 4.17: Stability of Slope at Section E-E During/Immediately after the Construction

Using UCS Test Results……………...…………………………………...….…..65

Figure 4.18: Stability of Slope at Section A-A During/Immediately after the Construction

using CU Test Results……………...……………………………….…...…...…..65

Figure 4.19: Stability of Slope at Section B-B During/Immediately after the Construction

using CU Test Results……………...……………………………….…...……….66

Figure 4.20: Stability of Slope at Section C-C During/Immediately after the Construction

using CU Test Results……………...……………………………….…...……….66

xxi

Figure 4.21: Stability of Slope at Section D-D During/Immediately after the Construction

using CU Test Results……………...……………………………….…...……….67

Figure 4.22: Stability of Slope at Section E-E During/Immediately after the Construction

using CU Test Results……………...……………………………….…...…….....67

Figure 4.23: Stability of Slope at Section A-A Long Time after the Construction using CU

Test Results……………...………………………………….………...……….....68

Figure 4.24: Stability of Slope at Section B-B Long Time after the Construction using CU

Test Results……………...…………………………..……….……...…………...68

Figure 4.25: Stability of Slope at Section C-C Long Time after the Construction using CU

Test Results……………...………………………….………...... ……….....69

Figure 4.26: Stability of Slope at Section D-D Long Time after the Construction using

CU Test Results……………...…………………………………….……...……...69

Figure 4.27: Stability of Slope at Section E-E Long Time after the Construction using CU

Test Results……………...………………………………………………...……..70

Figure 4.28: Stability of Slope at Section A-A During/Immediately after the Construction

(Total Stress Method)……………...…………………………………………...... 73

Figure 4.29: Stability of Slope at Section A-A Long Time after the Construction

(Effective Stress Method)….…………………………………...……….…….....73

Figure 4.30: Stability of Slope at Section B-B During/Immediately after the Construction

(Total Stress Method)……………..……………………………………………..74

xxii

Figure 4.31: Stability of Slope at Section B-B Long Time after the Construction

(Effective Stress Method) ……………………………………...………..………74

Figure 4.32: Stability of Slope at Section C-C During/Immediately after the Construction

(Total Stress Method)……………..……………………………………………..75

Figure 4.33: Stability of Slope at Section C-C Long Time after the Construction

(Effective Stress Method) ……………………………………...…………..……75

Figure 4.34: Stability of Slope at Section D-D During/Immediately after the Construction

(Total Stress Method)……………...…………………………………………...... 76

Figure 4.35: Stability of Slope at Section D-D Long Time after the Construction

(Effective Stress Method) ……………...…………………………………...…...76

Figure 4.36: Stability of Slope at Section E-E During/Immediately after the Construction

(Total Stress Method)……………..……………………………………………..77

Figure 4.37: Stability of Slope at Section E-E Long Time after the Construction

(Effective Stress Method) ……………...…………………………………...…...77

Figure 4.38: Mohr Envelope Drawn for UCS Test and CU Test (Effective) Results……79

xxiii

CHAPTER 1

INTRODUCTION

1.1 Background

In Ohio, there are more than one hundred coal-fired plants, which collectively use

over 50 million tons of coal each year. Around 90% of the total coal produced in or

imported to the state is used to generate electricity [8]. The production of FGD (Flue Gas

Desulfurization) material in Ohio is expected to increase significantly by 2012 [26]. The proper utilization or disposal of FGD material will be a big challenge for coal-fired power plants. At the same time, there are over 200,000 acres of unreclaimed strip-mined lands in the 30 coal producing counties in Ohio [26]. There are environmental and safety issues related to these abandoned mined lands that can be remediated using FGD materials [23,

26].

1.2 Research Objective

The main objective of this research work is to investigate the potential use of

FGD gypsum (in combination with fly ash and lime) as a backfill material for reclaiming

abandoned highwalls. Laboratory tests such as compaction, strength, permeability, and

solubility tests were conducted on various FGD gypsum mixes and slope stability

analyses were performed for a proposed demonstration project site close to the Conesville

power plant of American Electric Power (AEP).

In Chapter 2, an overview of the current state of practice for Coal Combustion

By-Products (CCBs) production and utilization is presented. Chapter 2 also discusses the

potential of abandoned mines and mine reclamation work completed in Ohio. Chapter 3

includes a presentation of the laboratory studies performed on various mixes of FGD gypsum, fly ash, and lime. This chapter also presents the measured sample strengths,

permeabilities, and solubilities of the FGD gypsum mixes. Chapter 4 includes the slope stability analyses using the FGD gypsum mix properties measured in Chapter 3. A summary of the research and the conclusion that can be drawn from the work are presented along with recommendations for additional studies in Chapter 5.

CHAPTER 2

BACKGROUND INFORMATION

2.1 Introduction

Coal-fired power plants have installed a variety of air pollution control technologies over the past 40 years resulting in a substantial increase in the production of coal combustion by-products [24]. In 2008, only 45% of CCBs were utilized beneficially, the rest were landfilled [2].

2.2 Production and Utilization of CCBs

More than 50% of the electricity generated in United States comes from burning coal [22]. In Ohio that number is close to 90% [26]. In the Midwestern and Eastern states, where the burning of high sulfur bituminous coal is common, regulations aimed at reducing the emissions of sulfur from flue gases have resulted in the production of large quantities of FGD gypsum and calcium sulfite rich material [15, 24].

Table 2.1 shows that around 17.7 million tons of FGD gypsum were produced in

2008 in the United States, out of which only 10.5 million tons (60%) were beneficially used in drywall panels, blended cement/raw feed for clinker, concrete, concrete products/

3 grouts, and agricultural applications. Currently, only a small amount of FGD material is being beneficially used in mining applications.

CCBs Produced Used % used Mostly Utilized in

(tons) (tons)

Fly Ash 72,454,230 30,142,274 41.60 Concrete, concrete products/grouts,

Blended cement/raw feed for clinker,

Structural fill, Mining applications,

Waste stabilization/solidification,

Soil modification/stabilization, etc.

Bottom Ash 18,431,297 8,076,255 43.82 Structural fills/embankments,

Aggregate, Road base/sub-base,

Snow & ice control, Concrete,

concrete products/grouts, Blended

cement/raw feed for clinker, etc.

Boiler Slag 2,028,455 1,689,892 83.31 Blasting grit/roofing granules,

Structural fills/embankments,

Mineral filler in asphalt, Snow and

ice control, etc.

FGD 17,754,939 10,653,344 60 Gypsum panel products, Blended

Gypsum cement/raw feed for clinker,

Concrete, concrete products/grouts,

Agriculture, etc.

Table 2.1: Production and Use of Coal Combustion Byproducts in 2008 in USA [2] 5

2.3 FGD Material Production Technologies

Conventionally, there are two types of FGD material production technologies :

wet FGD and dry FGD systems. In wet FGD technologies, the flue gas leaving the absorber is saturated and the slurry waste or by-product obtained is wet which is dewatered before disposal or sale. In dry FGD technologies, the flue gas leaving the absorber is not saturated and the waste generated is dry. The once-through technology is used widely, whereas the regenerable technology is used only marginally [20]. Once- through wet and dry FGD systems are described as below:

• Wet FGD systems: Approximately, 85% of total FGD systems in the US are wet

FGD systems [9]. In a wet FGD system, the flue gas is allowed to flow through

the absorber and an alkaline slurry. Depending on the manufacturer and the

desired process configurations, the absorber is spray tower or tray tower. The

sulfur dioxide present in the flue gas is removed by sorption in the absorber and

by reaction in the reaction tank. The spent sorbent (slurry bleed) from the reaction

tank is then dewatered and disposed of in the slurry pond [20].

• In a dry FGD system, the sorbent is added typically directly to the boiler. The

sulfur dioxide present in the flue gas reacts with the lime, whereas the heat of the

flue gas evaporates the water in the alkaline slurry and leaves behind a dry by-

product. Fabric filteration (baghouse) or electrostatic precipitation is used to

remove the by-product. Dry FGD systems mainly produce calcium sulfite with a

small amount of calcium sulfate [9].

In Ohio, wet FGD material is mainly of two types: fixated sulfite rich FGD and

sulfate rich FGD gypsum [8]. Since the production of FGD gypsum (sulfate rich) in Ohio

is likely to increase to 6.2 million tons by 2012, it remains a challenge to economically and safely use FGD gypsum in mine reclamation [26].

2.4 Physical and Chemical Properties of FGD Gypsum and Natural Gypsum

As can be seen from Table 2.3, both FGD gypsum and natural gypsum have the

same chemical composition, CaSO4∙2H2O. FGD gypsum typically has more free

moisture as compared to natural gypsum. Trace elements are similar in FGD gypsum and

natural gypsum. FGD gypsum has small and elongated crystal-like particles with the particle size ranging from 35 – 45 micron, whereas particles of natural gypsum are fairly uniform with large, flat, blocky crystals [14, 18].

Properties FGD Gypsum Natural Gypsum Chemical CaSO4∙2H2O CaSO4∙2H2O Composition Surface/free Moisture 6 – 25 % 0 – 3 %

Impurities Predominant impurity is unreacted Limestone Common impurity limestone (CaCO3, MgCO3)

Silica (SiO2) Present Present Calcium sulfite Present depending on the system Not present (CaSO4∙1/2H2O) Soluble salts (Mg+2, Present Present Na+, K+, Cl-1) Zn, Cd, Cr, Ni, Co, Cu, Pb, Tin, Trace Elements Same Mo, F, Ar, An, Hg, Se, Va

Table 2.2: Physical Properties of FGD Gypsum versus Natural Gypsum [14, 18]

Properties FGD gypsum Natural gypsum

35 – 45 micron, small, Fairly uniform, large, flat, Particle size elongated crystals blocky crystals Loose Bulk density 45 – 75 ~ 50 (lb/ft3)

Table 2.3: Chemical Properties of FGD Gypsum versus Natural Gypsum [14, 18]

2.5 Issues Related to Abandoned Mines and Reclamation

There are a number of environmental and safety issues related to abandoned and

unreclaimed strip-mined lands. Since 1999, more than 300 people have died in the US

due to these active and unreclaimed mines, out of which around 240 people were injured

or killed in abandoned unreclaimed mines [23].

Current regulations specify that mined lands be returned to their former land use

or for a new use [19] and the reclaimed lands should be allowed to achieve their

maximum economic value possible [7]. The main objectives of the reclamation and restoration of abandoned mined lands are [16, 25]:

• Eliminate the safety and health hazards related to abandoned mines

• Restore land and water resources

• Clean up sites to eliminate off-site environmental impacts

• Post mining land should have environmental and socio-economic benefits

• Guarantee a sustained mining operation

In March 1, 2006, The National Academy of Sciences (NAS) [10] concluded that

the use of CCBs in mine reclamation can be a feasible management option if

• CCBs are used in a properly planned way

• it avoids adverse impacts on the environment and public health.

• it includes the public involvement in issuing the regulatory permit process.

As this application has the potential to assist in meeting mine reclamation goals, avoids the need of landfills & impoundments, and significantly increase the utilization of CCBs, the NAS study concluded that CCBs could be beneficially used in mine reclamation with

appropriate material and site characterizations along with appropriate surface and ground

water monitoring. As CCB properties varies widely, these materials should be characterized before using in mine reclamation. Moreover, prior to a substantial placement of CCBs, a comprehensive site characterization should be conducted at the mine site. Additionally, CCBs should be placed in such a way so that contact with groundwater is minimized [10, 17].

2.6 Mine Reclamation in Ohio using FGD Gypsum

The total FGD material produced in Ohio in 2008 was about 4.2 million tons [26],

which is about 35% of the total FGD material produced in the US in 2008 [2]. Currently,

only 5% of the FGD material produced in Ohio is being used for mine reclamation,

whereas this number is just 1% in USA [26]. Considering that the production of FGD

gypsum will increase in the near future and the majority of the FGD materials produced

already go to landfills, the potential use of FGD gypsum in mine reclamation could be a

subject of extensive research.

There are seven completed (1993 to 2000) and three active mine reclamation

projects in Ohio which beneficially used or are using FGD material. Out of these ten

projects, only one is abandoned mine highwall project. The highwall project site is

located in Franklin Township, Coshocton County approximately 2 miles southwest of

Wills Creek. The 140 feet high and 1800 feet long highwall is only 1.5 miles from the

Conesville power plant. Stabilized FGD material is delivered from the Conesville power

plant for the reclamation work. It is estimated that a total of 1.7 million tons of Stabilized

FGD (Fixated sulfite rich FGD) material will be used to backfill this strip mine and

associated highwalls and pits. After backfilling with Stabilized FGD material, the top

surface will be covered by 12 inches of soil and then will be revegetated [26].

Table 2.2 shows the current and future production of FGD material at the five

FGD material producing power plants (Cardinal, Conesville, Gavin/Kyger Creek,

Muskingum River, and Sammis) in the Ohio coal mining region. It is believed that the production of FGD material in Ohio will increase to about 9.8 million tons (6.2 million tons of FGD gypsum and 3.6 million tons of Stabilized FGD material) per year by 2012

(Table 2.2). It is estimated that around 180-500 million cubic yards of FGD material can be beneficially used in reclaiming around 700 highwalls in the vicinity of the five power plants mentioned above [26]. This research is focused on evaluating the properties of the

CCBs, especially FGD gypsum, that may be used in the reclamation of abandoned highwall sites close to the Cardinal and Conesville power plants.

Future Production Current Production (tons) Total Coal-fired Power (tons) Production Plants Stabilized FGD FGD gypsum (tons) FGD gypsum

Cardinal 0 590,960 1,181,920 1,772,880

Conesville 936,000 0 761,840 1,697,840

Gavin/Kyger Creek 2,640,000 0 1,780,000 4,420,000

Muskingum River 0 0 665,720 665,720

Sammis 0 0 1,200,001 1,200,001

Total 3,576,000 590,960 5,589,481 9,756,441

Table 2.4: Production of FGD Material by Five FGD Material Producing Power

Plants in the Ohio Coal Mining Region [26]

2.7 Summary

In order to reduce the emission of sulfur dioxide, many coal-fired power plants in the US have installed air pollution control technologies, which have resulted in increased production of CCBs. Currently, beneficially utilizing or properly disposing CCBs is a big challenge for many coal-fired power plants. In 2008, only 45% of CCBs produced in the

US was beneficially used and around 60% of the FGD gypsum generated was beneficially used. Due to the installation of new scrubber systems, it is estimated that the production of FGD material in Ohio will increase to about 9.8 million tons per year by

2012. This material could be potentially used for the reclamation of abandoned highwalls.

CHAPTER 3

LABORATORY TESTS & RESULTS

3.1 Introduction

In this chapter, FGD gypsum and a combination of FGD gypsum, fly ash, and

lime are examined for their strengths, permeabilities, and solubilities. The different

combinations of FGD gypsum, fly ash, and lime tested in the laboratory are shown in

Table 3.1.

Fly ash acts as a mineral filler, thus the substitution of FGD gypsum with fly ash

may reduce the permeability of FGD gypsum. In the presence of fly ash, lime acts as an

activator of pozzolanic reaction. Therefore, the addition of fly ash and lime in FGD gypsum may reduce the permeability and may increase the shear strength of the FGD gypsum. The different combinations of FGD gypsum, fly ash, and lime (Table 3.1) studied here can be used in the mine reclamation work depending on the strength and permeability required for the application.

In Table 3.1, the 2% and 4% lime indicates the percent of lime with respect to the total dry weight of the FGD gypsum and fly ash mix. The results of laboratory tests (i.e., compaction, unconfined compressive strength, permeability, and solubility) performed on

14 FGD gypsum mixes for both Cardinal and Conesville FGD gypsum are discussed in

Section 3.3.2 and Section 3.3.3.

FGD Gypsum from Cardinal Power Plant

Lime (% by dry weight of FGD FGD Gypsum (%) Fly Ash (%) Gypsum & Fly Ash mix) 100 0 0 50 50 0 50 50 2 50 50 4 FGD Gypsum from Conesville Power Plant 100 0 0

Table 3.1: Proportions of FGD Gypsum, Fly Ash, and Lime Tested in Laboratory

3.2 Laboratory Tests

The laboratory tests performed on FGD gypsum mixes are as follows:

• Compaction test [4]: Standard Proctor Compaction tests were conducted to

establish the relationship between the moisture content and the dry unit weight

under standard compaction effort. The optimum moisture content and the

maximum dry unit weight obtained by the compaction tests were used to prepare

laboratory test samples. Moreover, the total unit weight required for the slope

stability analyses in Chapter 4 were obtained by using the maximum dry unit 15 weight (γd) and the optimum moisture content (ω) obtained from compaction

curves.

• Unconfined Compressive Strength Test [5]: The unconfined compressive strength

(UCS) tests were performed to provide a measure of the strength of the

compacted FGD gypsum mixes. The strengths of FGD gypsum mixes evaluated

in this chapter are used in the analyses of the stability of the side slopes of the

reclaimed areas in Chapter 4.

• Permeability Test [6]: In order to measure the permeability of FGD gypsum

mixes, standard falling head permeability tests were performed. Five pore

volumes of effluent were collected during each test.

• Solubility Test: The solubility tests were conducted to measure the amount of

solids present in the effluent. The effluent collected from permeability tests was

dried in an oven at 400C - 450C for 4 - 5 days and the percent solids present in the

effluent was calculated. Percent solid is the weight of solid in the effluent

expressed as a percentage (i.e., percent solid = 100 x weight of solid in the

effluent/weight of the effluent). The solubility of FGD gypsum mixes was then

evaluated as a function of pore volumes of water passed through the sample up to

five pore volumes of the effluent.

3.3 Laboratory Tests Samples and Results

3.3.1 Laboratory Tests Samples

Table 3.2 shows the number of samples prepared and the duration of curing prior

to conducting the laboratory tests. For every test, four samples were prepared and cured for 7 days, 28 days, 60 days, and 90 days in order to conduct laboratory test.

Size Total number Curing period Tests Length Diameter of Samples (days) (inches) (inches)

Strength Test 4 4 2 7, 28, 60, 90 days

Permeability Test 4 2 7, 28, 60, 90 days 4 Solubility Test 4 2 7, 28, 60, 90 days

NOTE: One sample was prepared for each curing period

Table 3.2: Details of the Samples made for Laboratory Tests

3.3.2 Laboratory Tests Results on Cardinal FGD Gypsum Samples

3.3.2.1 Compaction Test

Standard Proctor Compaction tests were performed to determine the optimum

moisture contents and the maximum dry unit weights of FGD gypsum mix samples. The

standard proctor test curves plotted for FGD gypsum mixes are shown in Figure 3.1. 17 Proctor Compaction Test

14.8 100 FGD 14.6 50 FGD, 50 FA 14.4 50 FGD, 50 FA, 2 L 14.2 50 FGD, 50 FA, 4 L 14.0

13.8

13.6

13.4

Dry Unit Weight (kN/m3) 13.2

13.0

12.8 0 5 10 15 20 25 30 Water Content (%)

Figure 3.1: Compaction Test Results for Cardinal FGD Gypsum Mixes

FGD Gypsum : Fly Ash : Maximum Dry Optimum

Lime (% by dry weight of Unit Weight Moisture Content

FGD Gypsum & Fly Ash) (kN/m3) (%)

14.6 100:0:0 16.4 14.3 50:50:0 19.3 14.1 50:50:2 21.3 14.2 50:50:4 21

Table 3.3: Maximum Dry Unit Weight and Optimum Moisture Content for Cardinal

FGD Gypsum, Fly Ash, and Lime Mix Samples

From Figure 3.1, it can be seen that the maximum dry unit weight of FGD

gypsum decreases and the optimum moisture content increases with the substitution of

the fly ash. The addition of lime in the mixture of FGD gypsum and fly ash further

reduces the maximum dry unit weight and increases the optimum moisture content.

A summary of the optimum moisture contents and the maximum dry unit weights

for FGD gypsum mixes are tabulated in Table 3.3. From Table 3.3 and Figure 3.1, 100%

FGD gypsum sample has a maximum dry unit weight of 14.6 kN/m3, which reduces to

14.3 kN/m3 on the substitution of 50% of FGD gypsum with 50% by weight of fly ash.

The maximum dry unit weight reduces to 14.1 kN/m3 and 14.2 kN/m3 with the addition

of 2% and 4% lime to the FGD gypsum and fly ash mix respectively. The optimum

moisture content of the 100% FGD gypsum sample is 16.4%, which increases to 19.3%

on the substitution of half of the FGD gypsum with fly ash. The optimum moisture

content increases to 21.3% and 21% with the addition of 2% and 4% of lime to the FGD

gypsum and fly ash mix respectively.

3.3.2.2 Strength Test

Unconfined Compressive Strength (UCS) tests were conducted on samples cured

for 7, 28, 60, and 90 days to measure the unconfined compressive strength of FGD

gypsum mixes. The unconfined compressive strengths are used to calculate the undrained

shear strength used in the slope stability analyses in Chapter 4.

In Figure 3.2, strengths of FGD gypsum mix samples are plotted as a function of

curing time. Table 3.4 summarizes the UCS test results for FGD gypsum, fly ash, and

19 lime mixes cured from 1 day to 8.5 months. As can be seen from Figure 3.2 and Table

3.4, the strength of the 100% FGD gypsum sample cured for 7 days is about 12 psi,

which increases to about 22 psi after 90 days of curing. The strength of the sample increases slightly with the increase in time. The strength of the FGD gypsum did not appear to be affected by the substitution of half of the FGD gypsum with fly ash. The

strength of 50% FGD gypsum and 50% fly ash sample increases from about 12 psi for 7

days to 16 psi for 90 days curing. Moreover, the strength of the sample containing 2% or

4% lime increases substantially with time. It is clear from Figure 3.2 that for the 50%

FGD gypsum, 50% fly ash, and 2% lime sample, the strength increases by a factor of five

i.e., from 42 psi to about 191 psi on increasing the curing time from 7 days to 28 days.

After 28 days of curing, the increase in the strength was from 191 psi to 225 psi and 234

psi for 28 days to 60 days and 90 days respectively. For the 50% FGD gypsum, 50% fly

ash, and 4% lime sample, the strength increased from 53 psi to 368 psi for 7 days to 28

days. The strengths achieved by sample after 60 days and 90 days of curing were 461 psi

and 535 psi respectively.

20 UCS Test Results 600

500

100 FGD 400 50 FGD, 50 FA 50 FGD, 50 FA, 2 L 300 50 FGD, 50 FA, 4 L UCS (psi) 200

100

0 0 20 40 60 80 100 Curing Time (days)

Figure 3.2: Strength of Cardinal FGD Gypsum, Fly Ash, and Lime Mix Samples

Cured for 7, 28, 60, and 90 Days

FGD gyp : FA : Unconfined Compressive Strength (psi)

L (% by dry 1 day 3 days 7 days 28 days 60 days 90 days 6 Months 8.5 Months weight)

100:0:0 9.8 9.7 11.9 15.1 24.0 22.2 - -

50:50:0 - 13.1 12.3 12.6 14.4 16.2 - -

50:50:2 - - 41.8 191.5 225.4 234.3 243.3 -

50:50:4 - - 52.6 368.5 460.6 535.1 - 582.1

Table 3.4: Unconfined Compressive Strengths of Cardinal FGD Gypsum, Fly Ash, and Lime Mix Samples Cured from 1

Day to 8.5 Months

22 100% FGD Gypsum 30 1 day 3 days 25 7 days 28 days 60 days 20 90 days

15 Stress (psi) Stress 10

0 0 0.01 0.02 0.03 0.04 0.05 Strain

Figure 3.3: Unconfined Compressive Strength of 100% Cardinal FGD Gypsum

Samples Cured for Six Different Time Periods

50% FGD Gypsum & 50% Fly Ash

18 3 days 16 7 days 28 days 14 60 days 90 days 12

8 Stress (psi) Stress 6

0 0 0.01 0.02 0.03 0.04 0.05 0.06 Strain

Figure 3.4: Unconfined Compressive Strength of 50% Cardinal FGD Gypsum and

50% Fly Ash Samples Cured for Five Different Time Periods

23 50% FGD Gypsum, 50% Fly Ash & 2% Lime

300 7 days 28 days 250 60 days 90 days 200 6 Months

150 Stress (psi) Stress 100

0 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 Strain

Figure 3.5: Unconfined Compressive Strength of 50% Cardinal FGD Gypsum, 50%

Fly Ash, and 2% Lime Samples Cured for Five Different Time Periods

50% FGD Gypsum, 50% Fly Ash & 4% Lime 700 7 days 600 28 days 60 days 500 90 days 8.5 Months 400

300 Stress (psi) Stress

200

100

0 0 0.005 0.01 0.015 0.02 0.025 0.03 Strain

Figure 3.6: Unconfined Compressive Strength of 50% Cardinal FGD Gypsum, 50%

Fly Ash, and 4% Lime Samples Cured for Five Different Time Periods

24 Figures 3.3 – 3.6 present the UCS test results for FGD gypsum mix samples cured for different periods. The residual strengths for the FGD gypsum mix samples without lime are less than 5 psi, whereas those for the FGD gypsum mixes with lime are approximately 50 psi or less. It appears from these figures that the stress-strain curves for the samples cured for 28 days or more are steeper than those cured for 7 days or less. This indicates that the modulus of elasticity increases with time when lime is added to the mixture of fly ash and FGD gypsum.

3.3.2.3 Permeability Test

Figure 3.7 shows the graph of permeability versus pore volume of effluent collected for 100% Cardinal FGD gypsum samples cured for 7 days, 28 days, 60 days, and 90 days. As can be seen, the permeability of samples reduces slightly with increase in the curing period. The permeability of the 100% FGD gypsum sample cured for 7 days is approximately 9 x 10-4 cm/sec, which reduces to 3.5 x 10-4 cm/sec after curing the sample for 90 days. The permeability of samples is essentially constant throughout the test.

25 100% FGD Gypsum 1.E-02

1.E-03

1.E-04

7 days 1.E-05 28 days Permeability (cm/sec) 60 days 90 days 1.E-06 0 1 2 3 4 5 6 Pore Volume

Figure 3.7: Permeability versus Pore Volume of Effluent for 100% Cardinal FGD

Gypsum Samples Cured for 7, 28, 60, and 90 Days

50% FGD Gypsum : 50% Fly Ash

1.E-02 7 days 28 days 1.E-03 60 days 90 days

1.E-04

1.E-05 Permeability (cm/sec) Permeability

1.E-06 0.00 1.00 2.00 3.00 4.00 5.00 6.00 Pore Volume

Figure 3.8: Permeability versus Pore Volume of Effluent for 50% Cardinal FGD

Gypsum and 50% Fly Ash Samples Cured for 7, 28, 60, and 90 Days

Figure 3.8 shows the permeability versus pore volume of effluent collected for

50% FGD gypsum and 50% fly ash mix samples cured for 7 days, 28 days, 60 days, and

90 days. The permeability is nearly constant throughout the test and the curing time does not significantly effect the permeability of the sample.

50% FGD Gypsum : 50% Fly Ash : 2% Lime 1.E-02 7 days 28 days 60 days 1.E-03 90 days

1.E-04

1.E-05 Permeability (cm/sec) Permeability

1.E-06 0.00 1.00 2.00 3.00 4.00 5.00 6.00 Pore Volume

Figure 3.9: Permeability versus Pore Volume of Effluent for 50% Cardinal FGD

Gypsum, 50% Fly Ash, and 2% Lime Samples Cured for 7, 28, 60, and 90 Days

Figure 3.9 indicates that the permeability of samples made up of 50% FGD gypsum, 50% fly ash, and 2% lime cured for 7, 28, 60, and 90 days is approximately 4 x

10-5 cm/sec. It appears that the addition of 2% lime decreases the permeability of the 50%

FGD gypsum and 50% fly ash mix sample by an order of magnitude. The curing period does not appear to have a significant effect on the measured permeability of the material.

50% FGD Gypsum : 50% Fly Ash : 4% Lime 1.E-02 7 days 28 days 60 days 1.E-03 90 days

1.E-04

1.E-05 Permeability (cm/sec) Permeability

1.E-06 0.00 1.00 2.00 3.00 4.00 5.00 6.00 Pore Volume

Figure 3.10: Permeability versus Pore Volume of Effluent for 50% Cardinal FGD

Gypsum, 50% Fly Ash, and 4% Lime Samples Cured for 7, 28, 60, and 90 Days

In Figure 3.10, the permeability of samples made up of 50% FGD gypsum, 50%

fly ash, and 4% lime cured for 7, 28, 60, and 90 days is presented. The permeability of

the 7 days cured sample is approximately 5 x 10-5 cm/sec, which reduces to 2 x 10-5

cm/sec on increasing the curing period to 90 days.

FGD gypsum : Fly ash : Lime Permeability (cm/sec)

(% by dry weight) 7 days 28 days 60 days 90 days

100:0:0 9.0 x10-4 5.0 x10-4 3.6 x10-4 3.5 x10-4

50:50:0 1.5 x10-4 1.5 x10-4 2.5 x10-4 1.7 x10-4

50:50:2 4.3 x10-5 4.3 x10-5 3.0 x10-5 3.7 x10-5

50:50:4 4.9 x10-5 3.7 x10-5 3.0 x10-5 2.0 x10-5

Table 3.5: Permeability of Cardinal FGD Gypsum, Fly Ash, and Lime Mix Samples

Cured for 7, 28, 60, and 90 Days

A summary of all the permeabilities of FGD gypsum mix samples cured for 7, 28,

60, and 90 days is tabulated in Table 3.5. It can be seen that there is a slight reduction in the permeability of FGD gypsum on the substitution of half of the FGD gypsum with fly

29 ash and further reduction by an order of magnitude, when lime is added to the mixture.

The permeabilities of FGD gypsum mixes reduce slightly on increasing the curing period.

3.3.2.4 Solubility Test

The solubility test results show the percent solids dissolved in the effluent

collected during the permeability tests. For 100% FGD gypsum samples, Figures 3.12 -

3.15 show that the percent solids collected in the effluent is typically higher initially but quickly decreases. After only about one pore volume of water has passed through the sample, the percent solid becomes essentially constant throughout the pore volume

measurements. The solubility curves for 100% FGD gypsum samples cured for 7, 28, 60, and 90 days shown in Figure 3.11 are almost the same, which indicates that the curing time does not significantly effect the solubility of the sample.

30 100% FGD Gypsum

0.7 7 days 28 days 0.6 60 days 90 days 0.5 7 days 28 days 0.4 60 days 90 days 0.3

Percent Solid (%) Solid Percent 0.2

0.1

0.0 0 1 2 3 4 5 6 Pore Volume

Figure 3.11: Percent Solid versus Pore Volume of Effluent for 100% Cardinal FGD

Gypsum Samples Cured for 7, 28, 60, and 90 Days

50% FGD Gypsum : 50% Fly Ash 0.7 7 days 28 days 0.6 60 days 90 days 0.5 7 days 28 days 60 days 0.4 90 days

0.3

Percent Solid (%) Solid Percent 0.2

0.1

0.0 0 1 2 3 4 5 6 Pore Volume

Figure 3.12: Percent Solid versus Pore Volume of Effluent for 50% Cardinal FGD

Gypsum and 50% Fly Ash Samples Cured for 7, 28, 60, and 90 Days 31

Figure 3.12 represents the solubility test results for 50% FGD gypsum and 50% fly ash samples cured for 7, 28, 60, and 90 days. Figure 3.12 indicates that initially the

percent solids is around 0.55%, which reduces to 0.25 - 0.30 % after two pore volumes of

water have been collected. It is clear from the figure that the curing time does not affect the solubility of the sample significantly and all the solubility curves are similar.

50% FGD Gypsum : 50% Fly Ash : 2% Lime

0.7 7 days 28 days 0.6 60 days 90 days 0.5 7 days 28 days 60 days 0.4 90 days

0.3

Percent Solid (%) Solid Percent 0.2

0.1

0.0 0 1 2 3 4 5 6 Pore Volume

Figure 3.13: Percent Solid versus Pore Volume of Effluent for 50% Cardinal FGD

Gypsum, 50% Fly Ash, and 2% Lime Samples Cured for 7, 28, 60, and 90 Days

For 50% FGD gypsum, 50% fly ash, and 2% lime samples, Figure 3.13 shows that initially percent solids collected in effluent is approximately 0.66%, which reduces to

0.25% - 0.30 % after a collection of 2.5 pore volumes of water. The 7 days cured sample has a higher solubility (i.e., ~ 0.42%) as compared to the samples cured for 28 days or more (i.e., approximately 0.25%). It appears from the figure that the solubility test curves for samples cured for 28 days or more are similar.

50% FGD Gypsum : 50% Fly Ash : 4% Lime 0.7 7 days 28 days 0.6 60 days 90 days 0.5 7 days 28 days 60 days 0.4 90 days

0.3

Percent Solid (%) Solid Percent 0.2

0.1

0.0 0 1 2 3 4 5 6 Pore Volume

Figure 3.14: Percent Solid versus Pore Volume of Effluent for 50% Cardinal FGD

Gypsum, 50% Fly Ash, and 4% Lime Samples Cured for 7, 28, 60, and 90 Days

Figure 3.14 shows the solubility test results for 50% FGD gypsum, 50% fly ash,

and 4% lime samples cured for 7, 28, 60, and 90 days. As can be seen from the figure that

the solubility of the 7 days cured sample after the first flush (i.e., 0.42% and more) is

higher than the solubility of 28, 60, and 90 days cured samples (i.e., around 0.30%) after the first flush. The initial percent solids collected for 50% FGD gypsum, 50% fly ash, and

4% lime samples cured for 28 days or more is approximately 0.60%, which reduces to

0.30% after the collection of 2.5 pore volumes of water. The solubility curves of the samples cured for 28, 60, and 90 days are similar.

Solubility Test (Average of Percent Solid Collected FGD gypsum : Fly Ash after 1 Pore Volume of Effluent is Collected) : Lime 7 days 28 days 60 days 90 days

100:0:0 0.27 0.26 0.28 0.26

50:50:0 0.28 0.27 0.27 0.26

50:50:2 0.43 0.30 0.29 0.28

50:50:4 0.49 0.32 0.30 0.30

Table 3.6: Percent Solid Collected from Effluent of Cardinal FGD Gypsum, Fly Ash,

and Lime Mix Samples Cured for 7, 28, 60, and 90 Days

A summary of the percent solids collected from effluent of FGD gypsum, fly ash, and lime mix samples cured for 7, 28, 60, and 90 days are shown in Table 3.6. It can be seen from Table 3.6 that the percent solids collected after the first flush for samples without added lime were similar at all the curing times studied. When lime was added to the FGD gypsum and fly ash mix, the amount of solids was higher for the seven days test than at later times by about 50%.

3.3.3 Laboratory Tests Results on Conesville FGD Gypsum

3.3.3.1 Compaction Test

Compaction tests were also performed on 100% FGD gypsum sample and 100%

FGD gypsum & 4% lime sample (Figure 3.15) for FGD gypsum obtained from the

Conesville power plant.

Conesville FGD Gypsum 16.0 100% FGD Gypsum 15.5 100% FGD Gypsum, 4% Li 15.0

14.5

14.0

13.5

13.0 Dry Unit Weight (kN/m3) Weight Unit Dry 12.5

12.0 0 5 10 15 20 25 30 35 40 Water Content (%)

Figure 3.15: Compaction Test Results for Conesville FGD Gypsum

Figure 3.15 shows that maximum dry unit weight for 100% Conesville FGD gypsum sample is 14.7 kN/m3 and the optimum moisture content is around 19%. For a

sample consisting 100% Conesville FGD gypsum and 4% lime, the maximum dry unit

weight is 14.4 kN/m3 and the optimum moisture content is approximately 19%. This

indicates that the addition of lime reduces the maximum dry unit weight by only 0.3

kN/m3, whereas the optimum moisture content remains nearly the same.

3.3.3.2 Strength Test

Figure 3.16 presents the UCS test results for the Conesville FGD gypsum samples. The strengths achieved by Conesville FGD gypsum and Cardinal FGD gypsum samples cured for 28 days are plotted in Figure 3.17 for comparison. The strength achieved by the Conesville FGD gypsum is less than half that achieved by the Cardinal

FGD gypsum.

Conesville FGD Gypsum 14 7 days 12 28 days 60 days 10 90 days

Stress(psi) 4

0 0 0.005 0.01 0.015 0.02 Strain

Figure 3.16: Unconfined Compressive Strength of Conesville FGD Gypsum Samples

Cured for Four Different Time Periods

FGD Gypsum (28 days Cured) 16 Cardinal 14 Conesville

6 Stress(psi)

0 0 0.005 0.01 0.015 0.02 0.025 0.03 Strain

Figure 3.17: Unconfined Compressive Strength of Conesville and Cardinal FGD

Gypsum Samples Cured for 28 Days

3.3.3.3 Permeability Test

Figure 3.18 shows the permeability of Conesville FGD gypsum samples cured for

7, 28, and 60 days. From Figure 3.18, it appears that the permeability of the samples remains constant throughout the test. The permeabilities of Conesville FGD gypsum samples are close to the measured permeabilities of the 100% Cardinal FGD gypsum samples.

Conesville FGD Gypsum

1.0E-02 7 days 28 days 60 days 1.0E-03

1.0E-04

1.0E-05 Permeability (cm/sec)

1.0E-06 0 1 2 3 4 5 6 Pore Volume

Figure 3.18: Permeability versus Pore Volume of Effluent for Conesville FGD

Gypsum Samples Cured for 7, 28, and 60 Days

3.3.3.4 Solubility Test

Figure 3.19 presents the percent solids collected in the five pore volumes of the effluent for Conesville FGD gypsum samples cured for 7, 28, and 60 days. The percent solids collected for Conesville FGD gypsum samples cured for 7, 28, and 60 days are comparable to the values measured for the Cardinal FGD gypsum samples after first flush

(see Figure 3.11).

Conesville FGD Gypsum

0.70 7 days 28 days 0.60 60 days

0.50

0.40

0.30

Percent SolidPercent (%) 0.20

0.10

0.00 0 1 2 3 4 5 6 Pore Volume

Figure 3.19: Percent Solid versus Pore Volume of Effluent for Conesville FGD

Gypsum Samples Cured for 7, 28, and 60 Days

3.4 Results and Discussion

The unconfined compressive strength of the FGD gypsum is not significantly affected by the substitution of fly ash (Table 3.7 and Table 3.10). However, the addition of 2% lime in the 50% FGD gypsum and 50% fly ash mix increases the strength by a factor of four after 7 days and by a factor of fifteen for samples cured for 90 days.

40 The substitution of half of the FGD gypsum with fly ash slightly reduces the permeability of the sample. The addition of 2% and 4% lime in the FGD gypsum and fly ash mix samples reduces the permeability of the mix by almost an order of magnitude.

Percent solids collected in the effluent for FGD gypsum mixes without lime is similar (i.e., 0.25% - 0.30%). Effluents from the samples containing lime exhibit a slightly higher percent solids content (i.e., 0.25% - 0.50%) especially at 7 days of curing as seen in Table 3.8. From Table 3.8 and Table 3.10, it appears that the curing time does not play a role in reducing the percent solids in the effluent for samples without lime.

However, for samples containing 2% lime, the percent solids collected in the effluent after first flush reduces from 0.43% for 7 days cured sample to 0.30% for 90 days cured sample. Similarly, for 4% lime samples, the percent solids collected in the effluent (after the first flush) reduces from 0.49% for 7 days cured sample to 0.30% for 90 days cured sample. The percent solids collected for samples containing lime is nearly unchanged

after 28 days.

Dry unit OMC UCS (psi) Mixes weight (%) (kN/m3) 7 days 28 days 60 days 90 days

100 FGD 16.4 14.6 11.9 15.1 24.0 22.2

50 FGD:50 FA 19.3 14.3 12.3 12.6 14.4 16.2

50 FGD:50 FA:2 L 20.5 14.1 41.8 191.5 225.5 234.3

50 FGD:50 FA:4 L 21 14.2 52.6 368.5 460.6 535.1

Note: FGD ~ FGD Gypsum (from Cardinal), FA ~ Fly ash, L ~ Lime, Moisture content and Percent solids in the effluent tested at 400C - 450C

Table 3.7: Optimum Moisture Content, Maximum Dry Unit Weight and Strength of

Cardinal FGD Gypsum Mix Samples Cured for Different Time Period

Permeability FGD : Permeability (cm/sec) FA : L % solids in Effluent Mixes 28 60 90 7 days 28 days 60 days 90 days 7 days days days days 9.0 x10-4 5.0 x10-4 3.6 x10-4 3.5 x10-4 100:0:0 0.27 0.26 0.28 0.26

1.5 x10-4 1.5 x10-4 2.5 x10-4 1.7 x10-4 50:50:0 0.28 0.27 0.27 0.26

4.3 x10-5 4.3 x10-5 3.0 x10-5 3.7 x10-5 50:50:2 0.43 0.30 0.29 0.28

4.9 x10-5 3.7 x10-5 3.0 x10-5 2.0 x10-5 50:50:4 0.49 0.32 0.30 0.30 Note: FGD ~ FGD Gypsum (from Cardinal), FA ~ Fly ash, L ~ Lime, Moisture content and Percent solids in the effluent tested at 400C - 450C

Table 3.8: Permeability and Percent Solids Collected in the Effluent of Cardinal

FGD Gypsum Mix Samples

Compaction Test Results

Mix OMC (%) Dry Density (kN/m3)

100% FGD gypsum 19.4 14.7

100% FGD gypsum and 4% lime 20 14.4

Table 3.9: Compaction Test Results for FGD Gypsum and FGD Gypsum & Lime

Mix Samples (FGD Gypsum Obtained from Conesville Power Plant)

Curing Period (days) Laboratory Test 7 days 28 days 60 days 90 days

UCS (psi) 6.7 8.6 12.2 8.8

Permeability (cm/sec) 5.E-04 2.E-04 5.E-04 -

% solids in Effluent 0.27 0.27 0.27 -

NOTE: Moisture content and Percent solids in the effluent tested at 400C - 450C

Table 3.10: UCS, Permeability and Percent Solids Collected in the Effluent for FGD

Gypsum Obtained from Conesville Power Plant

CHAPTER 4

SLOPE STABILITY ANALYSIS

4.1 Introduction

In this chapter, slope stability analyses of a proposed demonstration reclaimed abandoned mine site close to the Conesville power plant [21] are performed using the

SLOPE/W software. The four different backfill materials used to perform stability analyses in this chapter are as follows:

• FGD gypsum from Conesville power plant: For this case, total stress method was

used to analyze the stability of the slope. The undrained angle of friction, φu was

ignored and the undrained cohesion, cu was obtained by using UCS test result

presented in Chapter 3. These shear stress parameters were then used to perform

the short-term (during/immediately after construction) stability analyses.

• A mixture of FGD gypsum (50%) and fly ash (50%) from Cardinal power plant:

The UCS test results presented in Chapter 3 were used to obtain cu and total stress

analysis was used to perform the slope stability analyses. The results obtained in

this case represent the short-term stability case.

• FGD gypsum from Cardinal power plant: The short-term and long-term stability

analyses were done using UCS tests results presented in Chapter 3 and

45 Consolidated Undrained (CU) tests performed at the American Electric Power

(AEP) Civil Laboratory, Groveport, Ohio on August 01, 2008 [3].

• A mixture of Stabilized FGD material (33.33%), Fly ash (33.33%), and FGD

gypsum (33.33%): CU triaxial test results obtained from AEP report [21]. In this

case, total stress and effective stress parameters were used to analyze the stability

of slopes for short-term and long-term stability cases respectively.

4.2 About the SLOPE/W Software

SLOPE/W is a widely used slope stability software package that allows

computing of the factor of safety for both simple as well as complex slope problems.

Several of the most widely used limit equilibrium analysis methods including

Morgenstern-Price, Bishop, Janbu, and ordinary method of slices are available in the

SLOPE/W package. SLOPE/W displays the minimum factor of safety and the associated

slip surface [12].

4.3 Materials for Backfill and Their Properties

As mentioned earlier, four different backfill materials i.e. Conesville FGD

gypsum, Cardinal FGD gypsum, a mixture of Cardinal FGD gypsum & fly ash, and a

mixture of Conesville Stabilized FGD, fly ash, & FGD gypsum were used to perform stability analyses. Though it is expected that Conesville FGD gypsum will be used as backfill material to reclaim abandoned highwalls close to the Conesville power plant, slope stability analyses were also performed for Cardinal FGD gypsum, a mixture of

46 Cardinal FGD gypsum & fly ash, and a mixture of Conesville Stabilized FGD, fly ash, &

FGD gypsum as backfill material.

The material properties used in the analyses of the slopes are shown in Table 4.1.

The proprieties for spoil and a mixture of Stabilized FGD material, fly ash, and FGD gypsum were obtained from the AEP report [21]. The properties for Conesville FGD gypsum, Cardinal FGD gypsum, and Cardinal FGD gypsum & fly ash mix were obtained from the UCS tests performed on these samples in The OSU Soil Laboratory by the author. The properties of Cardinal FGD gypsum were also obtained from CU test results generated by AEP Civil Laboratory, Groveport, Ohio [3]. The highwall is of sandstone.

Therefore, the material properties used for highwall are those for sandstone [11, 13]. The phreatic surface (ground water table) was assumed to be as given in the AEP report GA

File no. 97-220 [21].

Friction angle Total unit Cohesion (kPa) Material (deg.) weight (kN/m3) Total Effective Total Effective

Spoil [21] 17.3 - 0 - 45

Highwall Material 21 - 4,000 - 0 [11, 13]

Conesville FGD 17.6 30 - 0 - gypsum

Cardinal FGD 17 43 - 0 - gypsum & fly ash

Cardinal FGD 17 52 - 0 - gypsum

Cardinal FGD 14.9 151.8 0 40.2 44.9 gypsum [3]

Stabilized FGD/ 15.7 28.2 0.5 29.6 37.6 FA/FGD gypsum [21]

Table 4.1: Material Properties used in Slope Stability Analyses

4.4 Slope Stability Analyses and Results on the Four Backfill Materials

The Morgenstern-Price method, which considers both shear and normal interslice forces and satisfies both moment and force equilibrium was used to analyze the stability of slopes in this report.

The stability of six slopes of mine reclamation final cap grade of the reclamation project sections 1-1, A-A, B-B, C-C, D-D, and E-E on the contour plot shown in Figure

4.1 were analyzed. The minimum factor of safety and the critical slip surface were plotted.

The slope at section 1-1 analyzed by Geo/Environmental Associates was included for comparison and method validation purposes. All the material properties used in the stability analysis for slope at section 1-1 were the same as those assumed by the

Geo/Environmental Associates. Additionally, Bishop’s method was used to analyze the stability of slope to compare the results with those generated by Geo/Environmental

Associates by using Modified Bishop’s method. The factor of safety (Figure 4.2) obtained for this section by using SLOPE/W software is 3.2 (Figure 4.2), whereas the factor of safety obtained by Geo/Environmental Associates by using STED software was 3.0. The slip surfaces obtained for the slope at section 1-1 by SLOPE/W are shallow and similar to the slip surfaces obtained by Geo/Environmental Associates using STED [21].

49 50

Figure 4.1: Mine Reclamation Final Cap Grade Showing Sections 1-1, A-A, B-B, C-C, D-D, and E-E [21]

Stability of Abandoned Mine Highwall Backfilled Slope at Section 1-1

Bishops Method

Name: Conesville FGD/FA/Gypsum Name: Spoil Name: Clayshale Unit Weight: 15.71 kN/m³ Unit Weight: 17.28 kN/m³ Unit Weight: 19.64 kN/m³ Cohesion: 0 kPa Cohesion: 0 kPa Cohesion: 47.88 kPa Phi: 30 ° Phi: 45 ° Phi: 30 °

18 17 3.2 16 15 14 13 12 11 10 9 Conesville FGD/FA/Gypsum 8 7 Spoil Highwall 6 5 GWT

Elevation (x feet) 10 4 3 2 1 0 0 5 10 15 20 25 30 35 40 45 50 55 Distance (x 10 feet)

NOTE: Zero elevation in the figure ~ 800 feet above sea level

Figure 4.2: Stability of Slope at Section 1-1

4.4.1 Conesville FGD gypsum as Backfill Material

Slope stability analyses were done for Conesville FGD gypsum using the total stress method. The unconfined compressive strength obtained for Conesville FGD gypsum in Chapter 3 was 8.6 psi (i.e., 60 kPa). In the total stress method, the undrained cohesion was taken as the half of the unconfined compressive strength (i.e., cu = 30 kPa) and the undrained angle of friction was neglected (u = 0). The unit weight was assumed to be the total unit weight calculated by using the maximum dry unit weight and the

51 optimum moisture content obtained from the compaction test in Chapter 3, Table 3.7. The factors of safety obtained for slopes at various sections are shown in Table 4.2.

Figure 4.3 – Figure 4.7 represent the minimum factors of safety and the most critical slip surfaces for slopes at the sections A-A, B-B, C-C, D-D, and E-E for short- term stability cases. From Figure 4.3, Figure 4.4, and Figure 4.7, it can be seen that the factors of safety of the slopes at sections A-A, B-B, and E-E for Conesville FGD gypsum as backfill material are 2.8, 3.3, and 3.2 respectively. Slip surfaces at these sections are very deep and are restricted to the backfill material. Figure 4.5 and Figure 4.6 indicate that the factors of safety of slopes at sections C-C and D-D are 3.4 and 3.5 respectively.

For these two sections, the slip surfaces are deep and slightly passed through the spoil.

Section Factor of Safety during/just after construction

A-A 2.8

B-B 3.3

C-C 3.4

D-D 3.5

E-E 3.2

Table 4.2: Factor of Safety of Slopes at the Five Sections using Conesville FGD

Gypsum as Backfill Material

52 NOTE: Zero elevation in Figures 4.3 – 4.37 ~ 800 feet above sea level

Stability of Abandoned Highwall Backfilled Slope at Section A-A

Method: Morgenstern-Price

Name: Conesville FGD Gypsum Name: Spoil Name: Highwall Unit Weight: 17.6 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 30 kPa Co h e si o n : 0 kP a Cohesion: 4000 kPa Phi: 0 ° Phi: 45 ° Phi: 0 °

17 16 2.8 15 14 13 12 11 10 9 Conesville FGD Gypsum 8 7 6 5 GW T Highw all

Elevation (x 10 feet) 10 (x Elevation 4 3 Spoil 2 1 0 0 5 10 15 20 25 30 35 40 45 Distance (x 10 feet)

Figure 4.3: Stability of Slope at Section A-A During/Immediately after the Construction for Conesville FGD Gypsum as Backfill Material

Stability of Abandoned Mine Highwall Backfilled Slope at Section B-B

Morgenstern-Price Method

Name: Conesville FGD Gypsum Name: Spoil Name: Highwall Unit Weight: 17.6 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 30 kPa Cohesion: 0 kPa Cohesion: 4000 kPa Phi: 0 ° Phi: 45 ° Phi: 0 °

17 3.3 16 15 14 13 12 11 10 9 Conesville FGD Gypsum Highwall 8 7 6 Spoil 5 GWT 4 Elevation(x 10 feet) 3 2 1 0 0 5 10 15 20 25 30 35 40 45 50 55 Distance (x 10 feet)

Figure 4.4: Stability of Slope at Section B-B During/Immediately after the Construction for Conesville FGD Gypsum as Backfill Material

53 Stability of Abandoned Mine Highwall Backfilled Slope at Section C-C

Method: Morgenstern-Price

Name: Conesville FGD Gypsum Name: Spoil Name: Highwall Unit Weight: 17.6 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 30 kPa Cohesion: 0 kPa Cohesion: 4000 kPa Phi: 0 ° Phi: 45 ° Phi: 0 ° 19 18 17 3.4 16 15 14 13 12 11 10 Highwall 9 Conesville FGD Gypsum 8 Spoil 7 6

Elevation (x 10 feet) (x Elevation 5 GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.5: Stability of Slope at Section C-C During/Immediately after the Construction for Conesville FGD Gypsum as Backfill Material

Stability of Abandoned Mine Highwall Backfilled Slope at Section D-D

Method: Morgenstern-Price

Name: Conesville FGD Gypsum Name: Spoil Name: Highw all Unit Weight: 17.6 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 0 kPa Cohesion: 4000 kPa 19 Cohesion: 30 kPa Phi: 45 ° Phi: 0 ° 18 Phi: 0 ° 17 16 3.5 15 14 13 12 11 10 9 Conesville FGD Gypsum Highwall 8 7 Spoil 6 5

Elevation (x10 feet) GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.6: Stability of Slope at Section D-D During/Immediately after the Construction for Conesville FGD Gypsum as Backfill Material

54 Stability of Abandoned Mine Highwall Backfilled Slope at Section E-E Method: Morgenstern-Price

Name: Conesville FGD Gypsum Name: Spoil Name: Highwall Unit Weight: 17.6 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 30 kPa Cohesion: 0 kPa Cohesion: 4000 kPa 15 Phi: 0 ° Phi: 45 ° Phi: 0 ° 14 13 3.2 12 11 10 9 8 Conesville FGD Gypsum 7 6 5 4 GWT Elevation (x feet)10 3 Spoil Highwall 2 1 0 0 5 10 15 20 25 30 Distance (x 10 feet)

Figure 4.7: Stability of Slope at Section E-E During/Immediately after the

Construction for Conesville FGD Gypsum as Backfill Material

4.4.2 A Mixture of Cardinal FGD Gypsum and Fly Ash as Backfill Material

A mixture of Cardinal FGD gypsum (50%) and fly ash (50%) is also assumed to be a backfill material and slope stability analyses were performed for the various sections shown in the contour plot (Figure 4.1). Slope stability analyses were performed using total stress method by using UCS test results. The UCS test results (Chapter 3, Table 3.7) for the mixture were used to determine the undrained cohesion, cu. The factors of safety obtained for various sections using 50% Cardinal FGD gypsum and 50% fly ash mix as backfill are shown in Table 4.3.

55 From Figure 4.8, Figure 4.10, and Figure 4.11, it can be seen that the factors of

safety for the slope at section A-A, C-C, and D-D are 3.9, 5.0, and 4.9 respectively and the slip surfaces are deep. The critical slip surfaces at these sections passed through the spoil. From Figure 4.9 and Figure 4.12, the factors of safety for the slopes at sections B-B

and E-E are 4.8 and 4.7 respectively. The slip surfaces are deep and restricted to the

backfill material.

Section Factor of Safety during/just after construction

A-A 3.9

B-B 4.8

C-C 5.0

D-D 4.9

E-E 4.7

Table 4.3: Factor of Safety of Slopes at Five Sections using a Mixture of Cardinal

FGD Gypsum and Fly Ash as Backfill Material

56 Stability of Abandoned Highwall Backfilled Slope at Section A-A

Method: Morgenstern-Price Name: Highwall Name: Cardinal FGD Gypsum & Fly Ash Name: Spoil Unit Weight: 25 kN/m³ Unit Weight: 17 kN/m³ Unit Weight: 17.3 kN/m³ Cohesion: 4000 kPa Cohesion: 43 kPa Cohesion: 0 kPa Phi: 0 ° Phi: 0 ° Phi: 45 °

17 16 3.9 15 14 13 12 11 10 9 Cardinal FGD Gypsum & Fly Ash 8 7 6 5 GW T Highw all

Elevation (x 10 feet) 10 (x Elevation 4 3 Spoil 2 1 0 0 5 10 15 20 25 30 35 40 45 Distance (x 10 feet)

Figure 4.8: Stability of Slope at Section A-A During/Immediately after the

Construction for Cardinal FGD Gypsum and Fly Ash Mix as Backfill Material

Stability of Abandoned Mine Highwall Backfilled Slope at Section B-B

Morgenstern-Price Method

17 4.8 16 15 14 13 12 11 10 9 Cardinal FGD Gypsum & Fly Ash Highwall 8 7 6 Spoil 5 GWT 4 Elevation(x feet) 10 3 2 1 0 0 5 10 15 20 25 30 35 40 45 50 55 Distance (x 10 feet)

Figure 4.9: Stability of Slope at Section B-B During/Immediately after the

Construction for Cardinal FGD Gypsum and Fly Ash Mix as Backfill Material

57 Stability of Abandoned Mine Highwall Backfilled Slope at Section C-C

Method: Morgenstern-Price

Name: Cardinal FGD Gypsum & Fly Ash Name: Spoil Name: Highwall Unit Weight: 17 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 43 kPa Cohesion: 0 kPa Cohesion: 4000 kPa Phi: 0 ° Phi: 45 ° Phi: 0 ° 19 18 17 5.0 16 15 14 13 12 11 10 Highwall 9 Cardinal FGD Gypsum & Fly Ash 8 Spoil 7 6

Elevation (x 10 feet) (x Elevation 5 GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.10: Stability of Slope at Section C-C During/Immediately after the Construction for Cardinal FGD Gypsum and Fly Ash Mix as Backfill Material

Stability of Abandoned Mine Highwall Backfilled Slope at Section D-D

Method: Morgenstern-Price

Name: Cardinal FGD Gypsum & Fly A sh Name: Spoil Name: Highw all Unit Weight: 17 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 0 kPa Cohesion: 4000 kPa 19 Cohesion: 43 kPa Phi: 45 ° Phi: 0 ° 18 Phi: 0 ° 17 16 4.9 15 14 13 12 11 10 9 Cardinal FGD Gypsum & Fly Ash Highwall 8 7 Spoil 6 5

Elevation(x feet) 10 GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.11: Stability of Slope at Section D-D During/Immediately after the Construction for Cardinal FGD Gypsum and Fly Ash Mix as Backfill Material 58

Stability of Abandoned Mine Highwall Backfilled Slope at Section E-E Method: Morgenstern-Price

Name: Cardinal FGD Gypsum & Fly Ash Name: Spoil Name: Highwall Unit Weight: 17 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 43 kPa Cohesion: 0 kPa Cohesion: 4000 kPa 15 Phi: 0 ° Phi: 45 ° Phi: 0 ° 14 13 4.7 12 11 10 9 8 Cardinal FGD Gypsum & Fly Ash 7 6 5 4 GWT Elevation (xfeet)10 3 Spoil Highwall 2 1 0 0 5 10 15 20 25 30 Distance (x 10 feet)

Figure 4.12: Stability of Slope at Section E-E During/Immediately after the

Construction for Cardinal FGD Gypsum and Fly Ash Mix as Backfill Material

4.4.3 Cardinal FGD Gypsum as Backfill Material

The third backfill material used to analyze the stability of slopes is Cardinal FGD gypsum. Slope stability analyses for this case were done by using three different sets of shear strength parameters as explained below:

 Total shear stress parameters were obtained by using UCS test results. The

unconfined compressive strength obtained by UCS tests on the Cardinal FGD gypsum

sample was 15.1 psi (i.e., 104 kPa) as shown in Chapter 3, Table 3.7. u was ignored

and cu was calculated to be 52 kPa. The total unit weight calculated by using the 59 maximum dry unit weight and the optimum moisture content obtained from the

compaction test in Chapter 3 was 17 kN/m3.

• Total shear stress parameters obtained by CU tests performed at AEP Civil

Engineering Laboratory, Groveport [3] were also used for slope stability analyses.

The total shear stress parameters from AEP report were as: φ = 40.20 and c = 3.17 ksf

= 151.8 kPa and the total unit weight was 14.9 kN/m3 [3].

• Effective Stress parameters were obtained from AEP report [3]. The shear stress

parameters obtained as per AEP report were as: φ’ = 44.90 and c’ = 0 ksf [3]. The total

unit weight obtained from AEP report was 14.9 kN/m3.

The slope stability analyses performed using total shear stress parameters

obtained from UCS test and CU test represent the case of short-term stability, whereas the

stability analysis performed using effective stress parameters obtained from CU test

represent the long-term stability case.

Figure 4.13 – Figure 4.17 show the factors of safety and the most critical slip

surfaces for slopes at the five sections (i.e., A-A, B-B, C-C, D-D, and E-E) obtained using

UCS test results. Factors of safety obtained for slopes at sections A-A, B-B, C-C, D-D, and E-E are 4.3, 5.6, 6.0, 5.7, and 5.7 respectively. It is clear from figures that slip surfaces for all of these sections are deep. The slip surfaces of sections A-A, B-B, C-C, and D-D passed through the spoil. The slip surface for slope at section E-E is restricted to the backfill material.

Figure 4.18 – Figure 4.22 represent the stability of slopes at various sections using total shear stress results obtained from CU test for the short-term stability case. From 60 these figures, the factors of safety at sections A-A, B-B, C-C, D-D, and E-E are 7.9, 15.6,

18.8, 20.7, and 22.9 respectively. The slip surfaces for sections A-A, B-B, C-C, and D-D are very deep and passed through the spoil. For section E-E, slip surface is deep and constraint to the backfill material.

Figure 4.23 – Figure 4.27 represent the stability of slopes long time after the construction. It can be seen from these figures that the factors of safety for slopes at sections A-A, B-B, C-C, D-D and E-E are 3.5, 5.0, 5.0, 5.0, and 3.0 respectively. All the critical slip surfaces for the slopes at the five sections are very shallow and are restricted to the backfill material.

Table 4.4 shows the factors of safety at various sections for both short-term stability and long-term stability cases. It is apparent from the table that all of the factors of safety are more than 1.0. Therefore, slopes at various sections should be stable during/immediately after construction as well as long time after the construction.

Factor of Safety

Section Short-term Long-term

UCS Test CU (Total stresses) CU (Effective Stresses)

A-A 4.3 7.9 3.5

B-B 5.6 15.6 5.0

C-C 6.0 18.8 5.0

D-D 5.7 20.7 5.0

E-E 5.7 22.9 3.0

Table 4.4: Factors of Safety of Slopes at Five Sections using Cardinal FGD Gypsum as Backfill Material

62 Stability of Abandoned Highwall Backfilled Slope at Section A-A

Method: Morgenstern-Price Name: Highwall Name: Cardinal FGD Gypsum Name: Spoil Unit Weight: 25 kN/m³ Unit Weight: 17 kN/m³ Unit Weight: 17.3 kN/m³ Cohesion: 4000 kPa Cohesion: 52 kPa Cohesion: 0 kPa Phi: 0 ° Phi: 0 ° Phi: 45 °

17 16 4.3 15 14 13 12 11 10 9 Cardinal FGD Gypsum 8 7 6 5 GW T Highw all

Elevation (x 10 feet) 10 (x Elevation 4 3 Spoil 2 1 0 0 5 10 15 20 25 30 35 40 45 Distance (x 10 feet)

Figure 4.13: Stability of Slope at Section A-A During/Immediately after the Construction using UCS Test Results

Stability of Abandoned Mine Highwall Backfilled Slope at Section B-B

Morgenstern-Price Method

Name: Cardinal FGD Gypsum Name: Spoil Name: Highwall Unit Weight: 17 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 52 kPa Cohesion: 0 kPa Cohesion: 4000 kPa Phi: 0 ° Phi: 45 ° Phi: 0 °

17 5.6 16 15 14 13 12 11 10 9 Cardinal FGD Gypsum Highwall 8 7 6 Spoil 5 GWT 4 Elevation(x 10 feet) 3 2 1 0 0 5 10 15 20 25 30 35 40 45 50 55 Distance (x 10 feet)

Figure 4.14: Stability of Slope at Section B-B During/Immediately after the Construction using UCS Test Results 63 Stability of Abandoned Mine Highwall Backfilled Slope at Section C-C

Method: Morgenstern-Price

Elevation (x 10 feet) 10 (x Elevation 5 GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.15: Stability of Slope at Section C-C During/Immediately after the Construction using UCS Test Results

Stability of Abandoned Mine Highwall Backfilled Slope at Section D-D

Method: Morgenstern-Price

Name: Cardinal FGD Gypsum Name: Spoil Name: Highw all Unit Weight: 17 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 0 kPa Cohesion: 4000 kPa 19 Cohesion: 52 kPa Phi: 45 ° Phi: 0 ° 18 Phi: 0 ° 17 16 5.7 15 14 13 12 11 10 9 Cardinal FGD Gypsum Highwall 8 7 Spoil 6 5

Elevation(x 10 feet) GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.16: Stability of Slope at Section D-D During/Immediately after the Construction using UCS Test Results

64 Stability of Abandoned Mine Highwall Backfilled Slope at Section E-E Method: Morgenstern-Price

Name: Cardinal FGD Gypsum Name: Spoil Name: Highwall Unit Weight: 17 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 52 kPa Cohesion: 0 kPa Cohesion: 4000 kPa 15 Phi: 0 ° Phi: 45 ° Phi: 0 ° 14 13 5.7 12 11 10 9 8 Cardinal FGD Gypsum 7 6 5 4 GWT Elevation (x feet)10 3 Spoil Highwall 2 1 0 0 5 10 15 20 25 30 Distance (x 10 feet)

Figure 4.17: Stability of Slope at Section E-E During/Immediately after the Construction using UCS Test Results

Stability of Abandoned Highwall Backfilled Slope at Section A-A

Method: Morgenstern-Price Name: Highwall Name: Cardinal FGD Gypsum Name: Spoil Unit Weight: 25 kN/m³ Unit Weight: 14.9 kN/m³ Unit Weight: 17.3 kN/m³ Cohesion: 4000 kPa Cohesion: 151.8 kPa Co h e si o n : 0 kP a Phi: 0 ° Phi: 40.2 ° Phi: 45 °

17 16 7.9 15 14 13 12 11 10 9 Cardinal FGD Gypsum 8 7 6 5 GW T Highw all

Elevation (x 10 feet) 10 (x Elevation 4 3 Spoil 2 1 0 0 5 10 15 20 25 30 35 40 45 Distance (x 10 feet)

Figure 4.18: Stability of Slope at Section A-A During/Immediately after the Construction using CU Test Results 65 Stability of Abandoned Mine Highwall Backfilled Slope at Section B-B

Morgenstern-Price Method

Name: Cardinal FGD Gypsum Name: Spoil Name: Highwall Unit Weight: 14.9 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 151.8 kPa Cohesion: 0 kPa Cohesion: 4000 kPa Phi: 40.2 ° Phi: 45 ° Phi: 0 °

17 15.6 16 15 14 13 12 11 10 9 Cardinal FGD Gypsum Highwall 8 7 6 Spoil 5 GWT 4 Elevation (x 10 feet) 3 2 1 0 0 5 10 15 20 25 30 35 40 45 50 55 Distance (x 10 feet)

Figure 4.19: Stability of Slope at Section B-B During/Immediately after the Construction using CU Test Results

Stability of Abandoned Mine Highwall Backfilled Slope at Section C-C

Method: Morgenstern-Price

Elevation (x 10 feet) 10 (x Elevation 5 GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.20: Stability of Slope at Section C-C During/Immediately after the Construction using CU Test Results 66 Stability of Abandoned Mine Highwall Backfilled Slope at Section D-D

Method: Morgenstern-Price

Name: Cardinal FGD Gypsum Name: Spoil Name: Highw all Unit Weight: 14.9 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 0 kPa Cohesion: 4000 kPa 19 Cohesion: 151.8 kPa Phi: 45 ° Phi: 0 ° 18 Phi: 40.2 ° 17 16 20.7 15 14 13 12 11 10 9 Cardinal FGD Gypsum Highwall 8 7 Spoil 6 5

Elevation (x feet) 10 GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.21: Stability of Slope at Section D-D During/Immediately after the

Construction using CU Test Results

Stability of Abandoned Mine Highwall Backfilled Slope at Section E-E Method: Morgenstern-Price

Name: Cardinal FGD Gypsum Name: Spoil Name: Highwall Unit Weight: 14.9 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 151.8 kPa Cohesion: 0 kPa Cohesion: 4000 kPa 15 Phi: 40.2 ° Phi: 45 ° Phi: 0 ° 14 13 22.9 12 11 10 9 8 Cardinal FGD Gypsum 7 6 5 4 GWT Elevation (xfeet)10 3 Spoil Highwall 2 1 0 0 5 10 15 20 25 30 Distance (x 10 feet)

Figure 4.22: Stability of Slope at Section E-E During/Immediately after the

Construction using CU Test Results

67 Stability of Abandoned Highwall Backfilled Slope at Section A-A

Method: Morgenstern-Price Name: Highwall Name: Cardinal FGD Gypsum Name: Spoil Unit Weight: 25 kN/m³ Unit Weight: 14.9 kN/m³ Unit Weight: 17.3 kN/m³ Cohesion: 4000 kPa Co h e si o n : 0 kP a Cohesion: 0 kPa Phi: 0 ° Phi: 44.9 ° Phi: 45 °

17 16 3.5 15 14 13 12 11 10 9 Cardinal FGD Gypsum 8 7 6 5 GW T Highw all

Elevation (x 10 feet) 10 (x Elevation 4 3 Spoil 2 1 0 0 5 10 15 20 25 30 35 40 45 Distance (x 10 feet)

Figure 4.23: Stability of Slope at Section A-A Long Time after the Construction

using CU Test Results

Stability of Abandoned Mine Highwall Backfilled Slope at Section B-B

Morgenstern-Price Method

Name: Cardinal FGD Gypsum Name: Spoil Name: Highwall Unit Weight: 14.9 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 0 kPa Cohesion: 0 kPa Cohesion: 4000 kPa Phi: 44.9 ° Phi: 45 ° Phi: 0 °

17 5.0 16 15 14 13 12 11 10 9 Cardinal FGD Gypsum Highwall 8 7 6 Spoil 5 GWT 4 Elevation (x 10 feet) 3 2 1 0 0 5 10 15 20 25 30 35 40 45 50 55 Distance (x 10 feet)

Figure 4.24: Stability of Slope at Section B-B long Time after the Construction using

CU Test Results 68 Stability of Abandoned Mine Highwall Backfilled Slope at Section C-C

Method: Morgenstern-Price

Elevation (x 10 feet) 5 GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.25: Stability of Slope at Section C-C Long Time after the Construction

using CU Test Results

Stability of Abandoned Mine Highwall Backfilled Slope at Section D-D

Method: Morgenstern-Price

Name: Cardinal FGD Gypsum Name: Spoil Name: Highw all Unit Weight: 14.9 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 0 kPa Cohesion: 4000 kPa 19 Cohesion: 0 kPa Phi: 45 ° Phi: 0 ° 18 Phi: 44.9 ° 17 16 5.0 15 14 13 12 11 10 9 Cardinal FGD Gypsum Highwall 8 7 Spoil 6 5

Elevation (x feet) 10 GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.26: Stability of Slope at Section D-D Long Time after the Construction

using CU Test Results 69 Stability of Abandoned Mine Highwall Backfilled Slope at Section E-E Method: Morgenstern-Price

Name: Cardinal FGD Gypsum Name: Spoil Name: Highwall Unit Weight: 14.9 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 0 kPa Cohesion: 0 kPa Cohesion: 4000 kPa 15 Phi: 44.9 ° Phi: 45 ° Phi: 0 ° 14 13 3.0 12 11 10 9 8 Cardinal FGD Gypsum 7 6 5 4 GWT Elevation (x10 feet) 3 Spoil Highwall 2 1 0 0 5 10 15 20 25 30 Distance (x 10 feet)

Figure 4.27: Stability of Slope at Section E-E Long Time after the Construction

using CU Test Results

4.4.4 A Mixture of Stabilized FGD Material/FA/FGD Gypsum as Backfill Material

A mixture of 33.3% Stabilized FGD, 33.3% fly ash, and 33.3% FGD gypsum was also used as backfill material to analyze the stability of slopes. The total unit weight and shear stress parameters of this mix were obtained from AEP report [21]. The shear strength properties of this mix obtained from CU tests are as follow:

 The total shear stress parameters obtained from the AEP report are:  = 29.60 and c =

3 28.2 kPa. Total unit weight, t = 15.7 kN/m .

• The shear stress parameters obtained from the AEP report are: φ’ = 37.60 and c’ = 0.5

3 kPa. Total unit weight, γt = 15.7 kN/m .

Figures 4.28, 4.30, 4.32, 4.34, and 4.36 show the factors of safety and the most critical slip surfaces obtained using total stress method for slopes at sections A-A, B-B,

C-C, D-D, and E-E respectively. The factors of safety for slopes at sections A-A, B-B, C-

C, D-D, and E-E are 4.5, 7.0, 7.2, 7.6, and 6.0 respectively. The slip surfaces for the short-term stability case are deep. Slip surfaces of slopes at sections A-A, B-B, and D-D

passed through the spoil. For slopes at section C-C and E-E, the slip surfaces are

constraint to the backfill material.

Figures 4.29, 4.31, 4.33, 4.35, and 4.37 show the factors of safety and the most

critical slip surfaces for long-term stability of slopes at sections A-A, B-B, C-C, D-D, and

E-E respectively. The factors of safety for slopes at sections A-A, B-B, C-C, D-D, and E-

E are 2.9, 4.3, 4.3, 4.3, and 2.7 respectively. Slip surfaces for the long-term stability cases are shallow and are restricted to the backfill material.

Table 4.5 indicates that the factors of safety for both short-term stability and long- term stability cases for slopes at all of the sections are more than 1.5. The factors of safety obtained for the short-term stability cases are higher than the factors of safety for the long-term stability cases.

Factor of Safety

Section Short-term Stability Long-term Stability

(Total stress method) (Effective Stress method)

A-A 4.5 2.9

B-B 7.0 4.3

C-C 7.2 4.3

D-D 7.6 4.3

E-E 6.0 2.7

Table 4.5: Factor of Safety at Five Sections Obtained by using a Mixture of

Stabilized FGD Material, Fly Ash, and FGD Gypsum as Backfill Material

72 Stability of Abandoned Highwall Backfilled Slope at Section A-A

Method: Morgenstern-Price Name: Highwall Name: Conesville FGD/FA/Gypsum Name: Spoil Unit Weight: 25 kN/m³ Unit Weight: 15.7 kN/m³ Unit Weight: 17.3 kN/m³ Cohesion: 4000 kPa Cohesion: 28.2 kPa Cohesion: 0 kPa Phi: 0 ° Phi: 29.6 ° Phi: 45 °

17 16 4.5 15 14 13 12 11 10 9 Conesville FGD/FA/Gypsum 8 7 6 5 GW T Highwall

Elevation (x 10 feet) 10 (x Elevation 4 3 Spoil 2 1 0 0 5 10 15 20 25 30 35 40 45 Distance (x 10 feet)

Figure 4.28: Stability of Slope at Section A-A During/Immediately after the

Construction (Total Stress Method)

Stability of Abandoned Highwall Backfilled Slope at Section A-A

Method: Morgenstern-Price Name: Highwall Name: Conesville FGD/FA/Gypsum Name: Spoil Unit Weight: 25 kN/m³ Unit Weight: 15.7 kN/m³ Unit Weight: 17.3 kN/m³ Cohesion: 4000 kPa Cohesion: 0.5 kPa Cohesion: 0 kPa Phi: 0 ° Phi: 37.6 ° Phi: 45 °

17 16 2.9 15 14 13 12 11 10 9 Conesville FGD/FA/Gypsum 8 7 6 5 GW T Highw all

Elevation (x 10 feet) 10 (x Elevation 4 3 Spoil 2 1 0 0 5 10 15 20 25 30 35 40 45 Distance (x 10 feet)

Figure 4.29: Stability of Slope at Section A-A Long Time after the Construction

(Effective Stress Method) 73 Stability of Abandoned Mine Highwall Backfilled Slope at Section B-B

Morgenstern-Price Method

17 7.0 16 15 14 13 12 11 10 9 Conesville FGD/FA/Gypsum Highwall 8 7 6 Spoil 5 GWT 4 Elevation(x feet) 10 3 2 1 0 0 5 10 15 20 25 30 35 40 45 50 55 Distance (x 10 feet)

Figure 4.30: Stability of Slope at Section B-B During/Immediately after the Construction (Total Stress Method)

Stability of Abandoned Mine Highwall Backfilled Slope at Section B-B

Morgenstern-Price Method

17 4.3 16 15 14 13 12 11 10 9 Conesville FGD/FA/Gypsum Highwall 8 7 6 Spoil 5 GWT 4 Elevation (x 10 feet) 3 2 1 0 0 5 10 15 20 25 30 35 40 45 50 55 Distance (x 10 feet)

Figure 4.31: Stability of Slope at Section B-B Long Time after the Construction (Effective Stress Method)

74 Stability of Abandoned Mine Highwall Backfilled Slope at Section C-C

Method: Morgenstern-Price

Name: Conesville FGD/FA/Gypsum Name: Spoil Name: Highwall Unit Weight: 15.7 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 28.2 kPa Cohesion: 0 kPa Cohesion: 4000 kPa Phi: 29.6 ° Phi: 45 ° Phi: 0 ° 19 18 17 7.2 16 15 14 13 12 11 10 Highwall 9 Conesville FGD/FA/Gypsum 8 Spoil 7 6

Elevation (x 10 feet) 10 (x Elevation 5 GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.32: Stability of Slope at Section C-C During/Immediately after the

Construction (Total Stress Method)

Stability of Abandoned Mine Highwall Backfilled Slope at Section C-C

Method: Morgenstern-Price

Name: Conesville FGD/FA/Gypsum Name: Spoil Name: Highwall Unit Weight: 15.7 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 0.5 kPa Cohesion: 0 kPa Cohesion: 4000 kPa Phi: 37.6 ° Phi: 45 ° Phi: 0 ° 19 18 17 4.3 16 15 14 13 12 11 10 Highwall 9 Conesville FGD/FA/Gypsum 8 Spoil 7 6

Elevation (x 10 feet) 5 GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.33: Stability of Slope at Section C-C Long Time after the Construction (Effective Stress Method) 75

Stability of Abandoned Mine Highwall Backfilled Slope at Section D-D

Method: Morgenstern-Price

Name: Conesville FGD/FA/Gyps um Name: Spoil Name: Highw all Unit Weight: 15.7 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 0 kPa Cohesion: 4000 kPa 19 Cohesion: 28.2 kPa Phi: 45 ° Phi: 0 ° 18 Phi: 29.6 ° 17 16 7.6 15 14 13 12 11 10 9 Conesville FGD/FA/Gypsum Highwall 8 7 Spoil 6 5

Elevation (x feet) 10 GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.34: Stability of Slope at Section D-D During/Immediately after the

Construction (Total Stress Method)

Stability of Abandoned Mine Highwall Backfilled Slope at Section D-D

Method: Morgenstern-Price

Name: Conesville FGD/FA/Gyps um Name: Spoil Name: Highw all Unit Weight: 15.7 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 0 kPa Cohesion: 4000 kPa 19 Cohesion: 0.5 kPa Phi: 45 ° Phi: 0 ° 18 Phi: 37.6 ° 17 16 4.3 15 14 13 12 11 10 9 Conesville FGD/FA/Gypsum Highwall 8 7 Spoil 6 5

Elevation (x feet) 10 GWT 4 3 2 1 0 0 10203040 Distance (x 10 feet)

Figure 4.35: Stability of Slope at Section D-D Long Time after the Construction

(Effective Stress Method) 76 Stability of Abandoned Mine Highwall Backfilled Slope at Section E-E Method: Morgenstern-Price

Name: Conesville FGD/FA/Gypsum Name: Spoil Name: Highwall Unit Weight: 15.7 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 28.2 kPa Cohesion: 0 kPa Cohesion: 4000 kPa 15 Phi: 29.6 ° Phi: 45 ° Phi: 0 ° 14 13 6.0 12 11 10 9 8 Conesville FGD/FA/Gypsum 7 6 5 4 GWT Elevation (x10 feet) 3 Spoil Highwall 2 1 0 0 5 10 15 20 25 30 Distance (x 10 feet)

Figure 4.36: Stability of Slope at Section E-E During/Immediately after the Construction (Total Stress Method)

Stability of Abandoned Mine Highwall Backfilled Slope at Section E-E Method: Morgenstern-Price

Name: Conesville FGD/FA/Gypsum Name: Spoil Name: Highwall Unit Weight: 15.7 kN/m³ Unit Weight: 17.3 kN/m³ Unit Weight: 25 kN/m³ Cohesion: 0.5 kPa Cohesion: 0 kPa Cohesion: 4000 kPa 15 Phi: 37.6 ° Phi: 45 ° Phi: 0 ° 14 13 2.7 12 11 10 9 8 Conesville FGD/FA/Gypsum 7 6 5 4 GWT Elevation (x feet)10 3 Spoil Highwall 2 1 0 0 5 10 15 20 25 30 Distance (x 10 feet)

Figure 4.37: Stability of Slope at Section E-E Long Time after the Construction

(Effective Stress Method) 77

4.5 Results and Discussion

The factors of safety obtained for slopes at five sections (A-A, B-B, C-C, D-D, and E-E) for the four different backfill materials (Conesville FGD gypsum, a mixture of

Cardinal FGD gypsum & fly ash, Cardinal FGD gypsum, and a mixture of Conesville

Stabilized FGD material, fly ash, & FGD gypsum) using total and effective stress methods are shown in Table 4.6. All the factors of safety obtained are greater than 1.

Therefore, slopes at various sections should be stable both during/immediately after the construction and long time after the construction.

The factors of safety obtained by using UCS test results are higher than those obtained by using effective CU test results. It is clear from the Figure 4.38 that for small

confining stresses, the shear strength of the backfill obtained by using effective CU test

results is less than that obtained by using UCS test results.

The factors of safety obtained for short-term stability by using total CU test

results are more than those obtained by using UCS test results. This might be because in

the CU test, the sample is consolidated and thus may have gained some shear strength.

The slip surfaces obtained for long-term stability case are very shallow, whereas those obtained for the short-term stability case are deep. Shallow slip surfaces are obtained for the case, where the angle of friction is high, which is obvious as the shear stress induced by friction increases with depth.

For total stress method, angle of friction is either zero (for UCS test) or almost negligible (total stress parameters from CU test). The cohesion does not get effected by

78 the confining stress i.e., cohesion is constant throughout the depth of the slope. Therefore, slip surfaces obtained for the short-term stability case using total stress method are deep.

Slip surfaces for the long term stability cases are restricted to the backfill material.

For short term stability cases, some of the slip surfaces passed through the spoil.

τ CU Test (Effective)

A φ

UCS Test cu

σΑ σ A

Figure 4.38: Mohr Envelope Drawn for UCS Test and CU Test (Effective) Results

4.6 Summary

In this chapter, slope stability analyses of a proposed demonstration reclaimed abandoned mine site close to Conesville power plant were performed using SLOPE/W software. The stability analysis of slopes at various sections of a contour map provided by AEP were performed during/immediately after the construction as well as long time after the construction for four different backfill materials. Factors of safety obtained for 79 the slopes at the five sections (i.e., A-A, B-B, C-C, D-D, and E-E) for both short-term and long-term stability cases are found to be more than 1.5. The critical slip surfaces for slopes at the five sections were studied. Slip surfaces obtained for short-term stability are deep, whereas those for long-term stability are shallow.

Factor of Safety for various backfill materials

Conesville Cardinal Section FGD gyp. Stabilized FGD/FA/FGD gyp. FGD gyp./FA FGD gypsum

S.T. (UCS) S.T. (CU) L.T. (CU) S.T. (UCS) S.T. (UCS) S.T. (CU) L.T. (CU)

A-A 2.8 4.5 2.9 3.9 4.3 7.9 3.5

B-B 3.3 7.0 4.3 4.8 5.6 15.6 5.0 8

1 C-C 3.4 7.2 4.3 5.0 6.0 18.8 5.0

D-D 3.5 7.6 4.3 4.9 5.7 20.7 5.0

E-E 3.2 6.0 2.7 4.7 5.7 22.9 3.0

NOTE: Stabilized FGD/FA/FGD gyp. ~ Mixture of Stabilized FGD (33.3%), fly ash (33.3%), and FGD gypsum (33.3%) FGD gyp. ~ FGD gypsum, FA ~ Fly ash, S.T. ~ Short-term, L.T. ~ Long-term CU ~ CU Test, UCS ~ UCS Test

Table 4.6: Factors of Safety at Five Sections Obtained for Four Different Backfill Materials

CHAPTER 5

CONCLUSIONS

5.1 Summary

It is expected that the production of FGD material in Ohio will increase to about

10 million tons per year by 2012. Out of this, over 6 million tons will be FGD gypsum.

Therefore, finding a way to properly utilize the FGD gypsum instead of landfilling is a challenge for many coal-fired power plants. Another challenge is to solve the environmental and social issues related to the abandoned mined highwalls left behind from pre-1970 mining.

This report is focused on how to use CCBs, especially FGD gypsum, in

abandoned mine highwalls in a technically sound way. In this research work, several

FGD gypsum mixes, which can be used as a backfill material in abandoned mine

highwalls/pits were studied. FGD gypsum and FGD gypsum mixes (with fly ash and

lime) were studied for permeability, solubility, and strength. The stability of slopes of

reclaimed mines using these mixes was also analyzed.

5.2 Conclusions

The conclusions made after performing laboratory experiments and analyzing

stability of slopes using SLOPE/W software are as follows:

• Compaction tests:

o The maximum dry density of FGD gypsum slightly reduced while the optimum moisture content slightly increased on the substitution of fly ash.

o The addition of lime in the FGD gypsum and fly ash mix further reduced the maximum dry density and increased the optimum moisture content of the mix.

• Unconfined Compressive Strength tests:

o The substitution of half of the FGD gypsum with fly ash in the absence of lime did not contribute to an increase in the strength of the FGD gypsum mix.

o The addition of lime in the mixture of FGD gypsum and fly ash substantially increased the strength of the mix.

o The curing period also contributed to the increase in the strength of the samples containing lime. For samples without lime, curing time did not impact measured

strength values.

• Permeability Tests:

o The permeability of FGD gypsum decreased slightly with the addition of fly ash.

o The addition of lime in the FGD gypsum and fly ash mix reduced the permeability of the mix by approximately an order of magnitude.

o There was an insignificant change in the permeability when the amount of lime was increased from 2% and 4%.

o The increase in the curing period slightly reduced the permeability.

o The permeabilities of FGD gypsum mix samples were similar throughout the tests of five pore volumes.

• Solubility Tests:

o Solubility of FGD gypsum and FGD gypsum mixes (with fly ash and lime) is low. Percent solids collected for FGD gypsum and the FGD gypsum and fly ash mix

was around 0.5% for the first flush, which reduced to 0.20-0.30% thereafter.

o The solubilities of samples without lime were not affected by the curing period.

o For samples containing lime, the solubility reduced from 0.5% to 0.3% on increasing the curing period from 7 days to 28 days. After 28 days, the reduction

in the solubility was insignificant.

• Slope Stability Analyses:

o Factors of safety for slopes using FGD gypsum and mixture of FGD gypsum & fly ash as backfill material were more than 1.5. Therefore, any of the FGD

gypsum mix could be used as a backfill material.

o As the factor of safety for 100% FGD gypsum backfilled slope is significantly higher than 1.5, the use of lime in the backfill would typically not be required.

o The slip surfaces for short-term stability cases are deep, whereas those for long- term stability are shallow.

o The factors of safety for short-term stability cases are greater than those for long- term stability are shallow.

5.3 Recommendation of Future Work

• Although FGD gypsum from Cardinal power plant and that from Conesville power

plants are similar, strength and permeability tests need to be performed on FGD

gypsum & fly ash mix samples for Conesville FGD gypsum.

• CU Triaxial tests for various FGD gypsum mixes for both Cardinal and Conesville

FGD gypsum should be conducted. The test results should then be used to analyze the

long-term stability of slopes.

• The stability of slopes was analyzed for a site close to Conesville power plant.

Although the slope stability results generated in Chapter 4 suggest that most

constructed slopes will be stable, slope stability analyses should be performed on a

site specific basis to evaluate the actual factor of safety and potential slip surface.

List of References

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m/m3))," ASTM International, West Conshohocken, PA, 2007.

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April 14, 2010.

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Appendix-A

Laboratory Test Data Sheets

Proctor Tests Performed

• 100% FGD Gypsum

• 50% FGD Gypsum and 50% Fly Ash

• 50% FGD Gypsum, 50% Fly Ash, and 2% Lime

• 50% FGD Gypsum, 50% Fly Ash, and 4% Lime

Moisture Content: Test Number 1 2 3 4 5 6 Date 2/1 2/1 2/1 2/2 2/2 2/2 Mass of can (g) 50.20 49.50 50.00 201.10 49.50 49.90 Mass can + wet soil (g) 100.10 97.20 101.50 285.50 110.90 102.10 Mass wet soil (g) 49.90 47.70 51.50 84.40 61.40 52.20 Mass dry soil + can (g) 96.50 92.60 95.40 273.60 101.20 92.10 Mass dry soil (g) 46.30 43.10 45.40 72.50 51.70 42.20 Mass water (g) 3.60 4.60 6.10 11.90 9.70 10.00 Water Content (%) 7.8 % 10.7 % 13.4 % 16.4 % 18.8 % 23.7 % Density and Unit Weight: Test Number 1 2 3 4 5 6 Water Content (%) 7.78 % 10.7 % 13.4 % 16.4 % 18.8 % 23.7 % Mass of mold (g) 4223.5 4223.5 4223.5 4223.5 4223.5 4328.7 Mass of mold + soil (g) 5638.2 5703.8 5771.3 5842.5 5864.9 5934.8 Mass of soil (g) 1414.7 1480.3 1547.8 1619.0 1641.4 1606.1 Volume of mold (cm3) 932.0 932.0 932.0 932.0 932.0 932.0 Wet unit weight (kN/m3) 14.89 15.58 16.29 17.04 17.27 16.90 Dry unit weight (kN/m3) 13.81 14.07 14.36 14.63 14.54 13.66

Table A.1: 100% Cardinal FGD Gypsum Compaction Test Data

Moisture Content: Test Number 1 2 3 4 5 6 7 8 Date 2/1 2/1 2/1 2/2 2/2 2/2 2/2 2/2 Mass of can (g) 50.0 50.20 203.5 209.0 121.5 201.0 121.5 49.90 Mass can+wet 87.1 96.60 271.8 245.6 168.3 250.1 166.4 107.2 soil(g) Mass wet soil (g) 37.1 46.40 68.30 36.60 46.80 49.10 44.90 57.30 Mass dry soil+can 82.4 89.10 258.5 242.8 163.7 245.6 160.60 95.10 (g) Mass dry soil (g) 32.4 38.90 55.00 33.80 42.20 44.60 39.10 45.20 Mass water (g) 4.7 7.50 13.30 2.80 4.60 4.50 5.80 12.10 Water Content 14.5 19.3 24.2 8.3 10.9 10.1 14.8 26.8 (%) Density and Unit Weight: Test Number 1 2 3 4 5 6 7 8 Water Content 14.5 19.3 24.2 8.28 10.9 10.1 14.8 26.8 (%) Mass of mold (g) 4223 4223 4223 4223 4223 4223 4223 4223 Mass of 5739 5841 5845 5613 5690 5648 5744 5850 mold+soil(g) Mass of soil (g) 1516 1618 1621 1389 1467 1425 1521 1626 Volume of 932 932 932 932 932 932 932 932 mold(cm3) Wet unit weight 15.9 17.0 17.1 14.6 15.4 15.0 16.0 17.1 (kN/m3) Dry unit weight 13.9 14.27 13.74 13.50 13.92 13.62 13.94 13.50 (kN/m3)

Table A.2: 50% Cardinal FGD Gypsum and 50% Fly Ash Mix Sample Compaction

Test Data

Moisture Content: Test Number 1 2 3 4 5 6 7 8 Date 2/1 2/1 2/1 2/2 2/2 2/2 2/2 2/2 Mass of can (g) 49.90 130.8 123.3 130.9 123.30 50.20 49.50 49.90 Mass can+wet soil 86.80 177.1 165.4 167.4 180.9 90.90 93.80 108.8 (g) Mass wet soil (g) 36.90 46.30 42.10 36.50 57.60 40.70 44.30 58.90 Mass dry soil+can (g) 83.00 170.2 158.0 164.4 169.7 84.90 86.60 98.40 Mass dry soil (g) 33.10 39.40 34.70 33.50 46.40 34.70 37.10 48.50 Mass water (g) 3.80 6.90 7.40 3.00 11.20 6.00 7.20 10.40 Water Content (%) 11.5 17.5 21.3 9.0 24.1 17.3 19.4 21.4 Density and Unit Weight: Test Number 1 2 3 4 5 6 7 8 Water Content (%) 11.5 17.5 21.3 8.96 24.1 17.3 19.4 21.4 Mass of mold (g) 4223 4223 4223 4223 4223 4223 4223 4223 Mass of mold+soil 5698 5797 5848 5611 5825 5756 5819 5848 (g) Mass of soil (g) 1474 1573 1624 1387 1601 1533 1596 1625 Volume of mold 932.0 932.0 932.0 932.0 932.0 932.0 932.0 932.0 (cm3) Wet unit weight 15.51 16.55 17.09 14.60 16.85 16.13 16.79 17.10 (kN/m3) Dry unit weight 13.92 14.09 14.09 13.40 13.57 13.75 14.06 14.08 (kN/m3)

Table A.3: 50% Cardinal FGD Gypsum, 50% Fly Ash, and 2% Lime Mix Sample

Compaction Test Data

Moisture Content: Test Number 1 2 3 4 5 6 7 8 Date 2/1 2/1 2/1 2/2 2/2 2/2 2/2 2/2 201.0 Mass of can (g) 50.00 49.80 50.20 50.20 50.20 50.20 50.10 0 Mass can+wet 103.5 252.6 89.30 86.20 95.70 94.00 89.20 92.90 soil (g) 0 0 Mass wet soil (g) 39.30 36.40 45.50 43.80 39.00 42.70 53.40 51.60 Mass dry 242.8 86.30 82.30 89.30 86.20 80.90 85.50 93.40 soil+can (g) 0 Mass dry soil (g) 36.30 32.50 39.10 36.00 30.70 35.30 43.30 41.80 Mass water (g) 3.00 3.90 6.40 7.80 8.30 7.40 10.10 9.80 Water Content 8.3 12.0 16.4 21.7 27.0 21.0 23.3 23.4 (%) Density and Unit

Weight: Test Number 1 2 3 4 5 6 7 8 Water Content 8.26 12 16.4 21.7 27 21 23.3 23.4 (%) 4223. 4223. 4223. 4223. 4223. 4223. 4223. Mass of mold (g) 4223.5 5 5 5 5 5 5 5 Mass of mold + 5566. 5664. 5836. 5799. 5851. 5843. 5826. 5759.6 soil (g) 6 3 9 4 0 0 3 1343. 1440. 1613. 1575. 1627. 1619. 1602. Mass of soil (g) 1536.1 1 8 4 9 5 5 8 Volume of mold 932.0 932.0 932.0 932.0 932.0 932.0 932.0 932.0 (cm3) Wet unit weight 14.13 15.16 16.16 16.98 16.58 17.13 17.04 16.87 (kN/m3) Dry unit weight 13.05 13.54 13.89 13.95 13.05 14.16 13.82 13.66 (kN/m3)

Table A.4: 50% Cardinal FGD Gypsum, 50% Fly Ash, and 4% Lime Mix Sample

Compaction Test Data

95 Permeability Test

Tests Performed

• 100% FGD Gypsum:

o 7 Days Cured Sample

o 28 Days Cured Sample

o 60 Days Cured Sample

o 90 Days Cured Sample

• 50% FGD Gypsum and 50% Fly Ash

o 7 Days Cured Sample

o 28 Days Cured Sample

o 60 Days Cured Sample

o 90 Days Cured Sample

• 50% FGD Gypsum, 50% Fly Ash, and 2% Lime

o 7 Days Cured Sample

o 28 Days Cured Sample

o 60 Days Cured Sample

o 90 Days Cured Sample

• 50% FGD Gypsum, 50% Fly Ash, and 4% Lime

o 7 Days Cured Sample

o 28 Days Cured Sample

o 60 Days Cured Sample

o 90 Days Cured Sample Examples of data sheets provided 96 Sample Data Diameter: 7.20 cm Mass: 999.7 g Height, Lo: 15.17 cm

Area, A: 40.7 cm3 Volume: 617.5 cm3 Initial h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 8.0 34.5 1:00:00 PM 1.2 0.0 5.0 2 10.1 34.5 1:00:15 PM 1.2 0.0 5.0 3 12.2 34.5 1:00:30 PM 1.2 0.0 5.0 4 14.1 34.5 1:00:45 PM 1.2 0.0 5.0 + ∆t h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 10.1 34.5 1:00:15 PM 1.2 0.0 5.0 2 12.2 34.5 1:00:30 PM 1.2 0.0 5.0 3 14.1 34.5 1:00:45 PM 1.2 0.0 5.0 4 16.1 34.5 1:01:00 PM 1.2 0.0 5.0

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -26.5 -24.4 -84.4 -110.9 -108.8 15 4.75 E-04 2 -24.4 -22.3 -84.4 -108.8 -106.7 15 4.84 E-04 3 -22.3 -20.4 -84.4 -106.7 -104.8 15 4.46 E-04 4 -20.4 -18.4 -84.4 -104.8 -102.8 15 4.79 E-04 Average Permeability 4.71 E-04

Table A.5: Permeability Data Sheet for 100% Cardinal FGD Gypsum Sample

Cured for 7 Days, 500 ml readings

Sample Data Diameter: 7.17 cm Mass: 975 g Height, Lo: 15.14 cm

Area, A: 40.4 cm3 Volume: 611.1 cm3 Initial h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 10.1 34.5 1:00:00 PM 1.1 0.0 5.0 2 12.2 34.5 1:00:15 PM 1.1 0.0 5.0 3 14.2 34.5 1:00:30 PM 1.1 0.0 5.0 4 16.2 34.5 1:00:45 PM 1.1 0.0 5.0 + ∆t h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 12.2 34.5 1:00:15 PM 1.1 0.0 5.0 2 14.2 34.5 1:00:30 PM 1.1 0.0 5.0 3 16.2 34.5 1:00:45 PM 1.1 0.0 5.0 4 18.1 34.5 1:01:00 PM 1.1 0.0 5.0

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -24.4 -22.3 -77.3 -101.7 -99.6 15 5.21 E-04 2 -22.3 -20.3 -77.3 -99.6 -97.6 15 5.07 E-04 3 -20.3 -18.3 -77.3 -97.6 -95.6 15 5.17 E-04 4 -18.3 -16.4 -77.3 -95.6 -93.7 15 5.02 E-04 Average Permeability 5.12 E-04

Table A.6: Permeability Data Sheet for 100% Cardinal FGD Gypsum Sample

Cured for 28 Days, 500 ml readings

Sample Data Diameter: 7.22 cm Mass: 969.1 g Height, Lo: 15.05 cm

Area, A: 40.9 cm3 Volume: 615.2 cm3 Initial

h1 h2 Pressure Pressure Pressure Test No. bottom Time bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1:00:00 1 12.4 34.5 1.2 0.0 5.0 PM 1:00:15 2 13.7 34.5 1.2 0.0 5.0 PM 1:00:30 3 15.1 34.5 1.2 0.0 5.0 PM 1:00:45 4 16.6 34.5 1.2 0.0 5.0 PM

+ ∆t h h Pressure Pressure Pressure Test No. 1 2 Time bottom (cm) top (cm) bottom (psi) top (psi) Cell (psi) 1 13.7 34.5 1:00:15 PM 1.2 0.0 5.0 2 15.1 34.5 1:00:30 PM 1.2 0.0 5.0 3 16.6 34.5 1:00:45 PM 1.2 0.0 5.0 4 18.0 34.5 1:01:00 PM 1.2 0.0 5.0

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -22.1 -20.8 -84.4 -106.5 -105.2 15 3.01 E-04 2 -20.8 -19.4 -84.4 -105.2 -103.8 15 3.29 E-04 3 -19.4 -17.9 -84.4 -103.8 -102.3 15 3.57 E-04 4 -17.9 -16.5 -84.4 -102.3 -100.9 15 3.38 E-04 Average Permeability 3.31 E-04

Table A.7: Permeability Data Sheet for 100% Cardinal FGD Gypsum Sample

Cured for 60 Days, 500 ml readings

Sample Data Diameter: 7.22 cm Mass: 1004.7 g Height, Lo: 15.05 cm

Area, A: 41.0 cm3 Volume: 616.6 cm3 Initial Pressur Test h1 h2 e Pressure Pressure Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 9.4 34.5 1:00:00 PM 1.1 0.0 5.0 2 10.8 34.5 1:00:15 PM 1.1 0.0 5.0 3 12.2 34.5 1:00:30 PM 1.1 0.0 5.0 4 13.6 34.5 1:00:45 PM 1.1 0.0 5.0 + ∆t Pressur Test h1 h2 e Pressure Pressure Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 10.8 34.5 1:00:15 PM 1.1 0.0 5.0 2 12.2 34.5 1:00:30 PM 1.1 0.0 5.0 3 13.6 34.5 1:00:45 PM 1.1 0.0 5.0 4 15.0 34.5 1:01:00 PM 1.1 0.0 5.0 Permeabilit Test ∆h ∆h∆ ∆P /γ h h ∆ ∆t y No. 0 t tot 0 tot t (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -25.1 -23.7 -77.3 -102.4 -101.0 15 3.37 E-04 2 -23.7 -22.3 -77.3 -101.0 -99.6 15 3.42 E-04 3 -22.3 -20.9 -77.3 -99.6 -98.2 15 3.47 E-04 4 -20.9 -19.5 -77.3 -98.2 -96.8 15 3.52 E-04 Average Permeability 3.44 E-04

Table A.8: Permeability Data Sheet for 100% Cardinal FGD Gypsum Sample

Cured for 90 Days, 500 ml readings

100

Sample Data Diameter: 7.23 cm Mass: 1098.5 g Height, Lo: 15.19 cm

Area, A: 41.1 cm3 Volume: 623.9 cm3 Initial h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1:00:00 1 3.1 34.5 1.2 0.0 5.0 PM 1:00:30 2 4.7 34.5 1.2 0.0 5.0 PM 1:01:00 3 6.1 34.5 1.2 0.0 5.0 PM 1:01:30 4 7.4 34.5 1.2 0.0 5.0 PM + ∆t h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1:00:30 1 4.7 34.5 1.2 0.0 5.0 PM 1:01:00 2 6.1 34.5 1.2 0.0 5.0 PM 1:01:30 3 7.4 34.5 1.2 0.0 5.0 PM 1:02:00 4 8.8 34.5 1.2 0.0 5.0 PM

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -31.4 -29.8 -84.4 -115.8 -114.2 30 1.72 E-04 2 -29.8 -28.4 -84.4 -114.2 -112.8 30 1.52 E-04 3 -28.4 -27.1 -84.4 -112.8 -111.5 30 1.43 E-04 4 -27.1 -25.7 -84.4 -111.5 -110.1 30 1.56 E-04 Average Permeability 1.56 E-04

101 Table A.9: Permeability Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix

Sample Cured for 7 Days, 500 ml readings

Sample Data Diameter: 7.21 cm Mass: 1085.5 g Height, Lo: 15.13 cm

Area, A: 40.8 cm3 Volume: 617.2 cm3 Initial h h Pressure Pressure Pressure Test 1 2 bottom Time bottom No. (cm) top (cm) (psi) top (psi) Cell (psi) 1 11.1 34.5 1:00:00 PM 1.1 0.0 5.0 2 13.4 34.5 1:01:00 PM 1.1 0.0 5.0 3 15.5 34.5 1:02:00 PM 1.1 0.0 5.0 4 17.7 34.5 1:03:00 PM 1.1 0.0 5.0 + ∆t h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 13.4 34.5 1:01:00 PM 1.1 0.0 5.0 2 15.5 34.5 1:02:00 PM 1.1 0.0 5.0 3 17.7 34.5 1:03:00 PM 1.1 0.0 5.0 4 19.9 34.5 1:04:00 PM 1.1 0.0 5.0

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -23.4 -21.1 -77.3 -100.7 -98.4 60 1.43 E-04 2 -21.1 -19 -77.3 -98.4 -96.3 60 1.33 E-04 3 -19 -16.8 -77.3 -96.3 -94.1 60 1.43 E-04 4 -16.8 -14.6 -77.3 -94.1 -91.9 60 1.46 E-04 Average Permeability 1.41 E-04

Table A.10: Permeability Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix

Sample Cured for 28 Days, 500 ml readings

102

Sample Data Diameter: 7.26 cm Mass: 1006.6 g Height, Lo: 15.37 cm

Area, A: 41.4 cm3 Volume: 636.9 cm3 Initial h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 10.0 34.5 1:00:00 PM 1.1 0.0 5.0 2 11.8 34.5 1:00:30 PM 1.1 0.0 5.0 3 13.7 34.5 1:01:00 PM 1.1 0.0 5.0 4 15.7 34.5 1:01:30 PM 1.1 0.0 5.0 + ∆t h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 11.8 34.5 1:00:30 PM 1.1 0.0 5.0 2 13.7 34.5 1:01:00 PM 1.1 0.0 5.0 3 15.7 34.5 1:01:30 PM 1.1 0.0 5.0 4 17.7 34.5 1:02:00 PM 1.1 0.0 5.0

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -24.5 -22.7 -77.3 -101.8 -100.0 30 2.20 E-04 2 -22.7 -20.8 -77.3 -100.0 -98.1 30 2.37 E-04 3 -20.8 -18.8 -77.3 -98.1 -96.1 30 2.54 E-04 4 -18.8 -16.8 -77.3 -96.1 -94.1 30 2.60 E-04 Average Permeability 2.43 E-04

Table A.11: Permeability Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix

Sample Cured for 60 Days, 500 ml readings

103

Sample Data Diameter: 7.26 cm Mass: 1052.2 g Height, Lo: 15.24 cm

Area, A: 41.4 cm3 Volume: 631.3 cm3 Initial h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 10.9 34.5 1:00:00 PM 1.0 0.0 5.0 2 13.4 34.5 1:01:00 PM 1.0 0.0 5.0 3 15.8 34.5 1:02:00 PM 1.0 0.0 5.0 4 18.1 34.5 1:03:00 PM 1.0 0.0 5.0 + ∆t h h Pressure Pressure Pressure Test 1 2 bottom Time bottom No. (cm) top (cm) (psi) top (psi) Cell (psi) 1 13.4 34.5 1:01:00 PM 1.0 0.0 5.0 2 15.8 34.5 1:02:00 PM 1.0 0.0 5.0 3 18.1 34.5 1:03:00 PM 1.0 0.0 5.0 4 20.4 34.5 1:04:00 PM 1.0 0.0 5.0

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -23.6 -21.1 -70.3 -93.9 -91.4 60 1.65 E-04 2 -21.1 -18.7 -70.3 -91.4 -89.0 60 1.63 E-04 3 -18.7 -16.4 -70.3 -89.0 -86.7 60 1.60 E-04 4 -16.4 -14.1 -70.3 -86.7 -84.4 60 1.65 E-04 Average Permeability 1.63 E-04

Table A.12: Permeability Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix

Sample Cured for 90 Days, 500 ml readings

104

Sample Data Diameter: 7.28 cm Mass: 1041.6 g Height, Lo: 15.32 cm

Area, A: 41.6 cm3 Volume: 636.8 cm3 Initial h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 10.3 34.5 1:00:00 PM 2.1 0.0 6.2 2 12.5 34.5 1:02:00 PM 2.3 0.0 6.2 3 14.7 34.5 1:04:00 PM 2.1 0.0 6.2 4 17.0 34.5 1:06:00 PM 2.3 0.0 6.2 + ∆t h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 12.5 34.5 1:02:00 PM 2.3 0.0 6.2 2 14.7 34.5 1:04:00 PM 2.1 0.0 6.2 3 17.0 34.5 1:06:00 PM 2.3 0.0 6.2 4 19.1 34.5 1:08:00 PM 2.2 0.0 6.2

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -24.2 -22 -147.6 -171.8 -169.6 120 3.96 E-05 2 -22 -19.8 -161.7 -183.7 -181.5 120 3.70 E-05 3 -19.8 -17.5 -147.6 -167.4 -165.1 120 4.25 E-05 4 -17.5 -15.4 -161.7 -179.2 -177.1 120 3.62 E-05 Average Permeability 3.88 E-05

Table A.13: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2%

Lime Mix Sample Cured for 7 Days, 500 ml readings

105

Sample Data Diameter: 7.28 cm Mass: 1041.6 g Height, Lo: 15.32 cm

Area, A: 41.6 cm3 Volume: 636.8 cm3 Initial

H1 h2 Pressure Pressure Pressure Test No. Bottom Time bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1:00:00 1 10.3 34.5 2.1 0.0 6.2 PM 1:02:00 2 12.5 34.5 2.3 0.0 6.2 PM 1:04:00 3 14.7 34.5 2.1 0.0 6.2 PM 1:06:00 4 17.0 34.5 2.3 0.0 6.2 PM

+ ∆t h h Pressure Pressure Pressure Test No. 1 2 Time bottom (cm) top (cm) bottom (psi) top (psi) Cell (psi) 1 12.5 34.5 1:02:00 PM 2.3 0.0 6.2 2 14.7 34.5 1:04:00 PM 2.1 0.0 6.2 3 17.0 34.5 1:06:00 PM 2.3 0.0 6.2 4 19.1 34.5 1:08:00 PM 2.2 0.0 6.2

Table A.14: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2%

Lime Mix Sample Cured for 28 Days, 500 ml readings

106

Sample Data Diameter: 7.30 cm Mass: 1049 g Height, Lo: 15.33 cm

Area, A: 41.8 cm3 Volume: 640.9 cm3 Initial

H1 h2 Pressure Pressure Pressure Test No. Bottom Time bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1:00:00 1 8.0 34.5 2.1 0.0 6.2 PM 1:03:00 2 10.9 34.5 2.3 0.0 6.2 PM 1:06:00 3 13.8 34.5 2.3 0.0 6.2 PM 1:09:00 4 16.7 34.5 2.2 0.0 6.2 PM

+ ∆t h h Pressure Pressure Pressure Test No. 1 2 Time bottom (cm) top (cm) bottom (psi) top (psi) Cell (psi) 1 10.9 34.5 1:03:00 PM 2.3 0.0 6.2 2 13.8 34.5 1:06:00 PM 2.3 0.0 6.2 3 16.7 34.5 1:09:00 PM 2.2 0.0 6.2 4 19.5 34.5 1:12:00 PM 2.2 0.0 6.2

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -26.5 -23.6 -147.6 -174.1 -171.2 180 3.42 E-05 2 -23.6 -20.7 -161.7 -185.3 -182.4 180 3.21 E-05 3 -20.7 -17.8 -161.7 -182.4 -179.5 180 3.26 E-05 4 -17.8 -15 -154.7 -172.5 -169.7 180 3.33 E-05 Average Permeability 3.31 E-05

Table A.15: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2%

Lime Mix Sample Cured for 60 Days, 500 ml readings

107

Sample Data Diameter: 7.28 cm Mass: 1037.3 g Height, Lo: 15.30 cm

Area, A: 41.6 cm3 Volume: 636.5 cm3 Initial

H1 h2 Pressure Pressure Pressure Test No. Bottom Time bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1:00:00 1 8.0 34.5 2.3 0.0 6.1 PM 1:03:00 2 11.5 34.5 2.3 0.0 6.1 PM 1:06:00 3 15.0 34.5 2.1 0.0 6.1 PM 1:09:00 4 18.4 34.5 2.2 0.0 6.1 PM

+ ∆t h h Pressure Pressure Pressure Test No. 1 2 Time bottom (cm) top (cm) bottom (psi) top (psi) Cell (psi) 1 11.5 34.5 1:03:00 PM 2.3 0.0 6.1 2 15.0 34.5 1:06:00 PM 2.1 0.0 6.1 3 18.4 34.5 1:09:00 PM 2.2 0.0 6.1 4 21.8 34.5 1:12:00 PM 2.3 0.0 6.1

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -26.5 -23 -161.7 -188.2 -184.7 180 3.83 E-05 2 -23 -19.5 -161.7 -184.7 -181.2 180 3.91 E-05 3 -19.5 -16.1 -147.6 -167.1 -163.7 180 4.20 E-05 4 -16.1 -12.7 -154.7 -170.8 -167.4 180 4.11 E-05 Average Permeability 4.01 E-05

Table A.16: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2%

Lime Mix Sample Cured for 90 Days, 500 ml readings

108

Sample Data Diameter: 7.30 cm Mass: 1070.6 g Height, Lo: 15.29 cm

Area, A: 41.9 cm3 Volume: 640.6 cm3 Initial h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 11.0 34.5 1:00:00 PM 1.1 0.0 5.0 2 12.7 34.5 1:02:00 PM 1.1 0.0 5.0 3 14.3 34.5 1:04:00 PM 1.1 0.0 5.0 4 16.0 34.5 1:06:00 PM 1.1 0.0 5.0 + ∆t h h Pressure Pressure Pressure Test 1 2 bottom Time bottom No. (cm) top (cm) (psi) top (psi) Cell (psi) 1 12.7 34.5 1:02:00 PM 1.1 0.0 5.0 2 14.3 34.5 1:04:00 PM 1.1 0.0 5.0 3 16.0 34.5 1:06:00 PM 1.1 0.0 5.0 4 17.7 34.5 1:08:00 PM 1.1 0.0 5.0

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -23.5 -21.8 -77.3 -100.8 -99.1 120 5.17 E-05 2 -21.8 -20.2 -77.3 -99.1 -97.5 120 4.95 E-05 3 -20.2 -18.5 -77.3 -97.5 -95.8 120 5.35 E-05 4 -18.5 -16.8 -77.3 -95.8 -94.1 120 5.45 E-05 Average Permeability 5.23 E-05

Table A.17: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4%

Lime Mix Sample Cured for 7 Days, 500 ml readings

109

Sample Data Diameter: 7.31 cm Mass: 1053.9 g Height, Lo: 15.32 cm

Area, A: 41.9 cm3 Volume: 642.7 cm3 Initial

H1 h2 Pressure Pressure Pressure Test No. Bottom Time bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1:00:00 1 10.7 34.5 1.1 0.0 5.0 PM 1:04:00 2 13.2 34.5 1.1 0.0 5.0 PM 1:08:00 3 15.8 34.5 1.1 0.0 5.0 PM 1:12:00 4 18.4 34.5 1.1 0.0 5.0 PM

< + ∆t h h Pressure Pressure Pressure Test No. 1 2 Time bottom (cm) top (cm) bottom (psi) top (psi) Cell (psi) 1 13.2 34.5 1:04:00 PM 1.1 0.0 5.0 2 15.8 34.5 1:08:00 PM 1.1 0.0 5.0 3 18.4 34.5 1:12:00 PM 1.1 0.0 5.0 4 20.8 34.5 1:16:00 PM 1.1 0.0 5.0

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -23.8 -21.3 -77.3 -101.1 -98.6 240 3.81 E-05 2 -21.3 -18.7 -77.3 -98.6 -96.0 240 4.07 E-05 3 -18.7 -16.1 -77.3 -96.0 -93.4 240 4.18 E-05 4 -16.1 -13.7 -77.3 -93.4 -91.0 240 3.96 E-05 Average Permeability 4.00 E-05

Table A.18: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4%

Lime Mix Sample Cured for 28 Days, 500 ml readings

110

Sample Data Diameter: 7.31 cm Mass: 1034.7 g Height, Lo: 15.30 cm

Area, A: 42.0 cm3 Volume: 642.4 cm3 Initial

H1 h2 Pressure Pressure Pressure Test No. Bottom Time bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1:00:00 1 10.1 34.5 2.4 0.0 6.3 PM 1:03:00 2 12.8 34.5 2.2 0.0 6.3 PM 1:06:00 3 15.5 34.5 2.2 0.0 6.3 PM 1:09:00 4 18.1 34.5 2.2 0.0 6.3 PM

+ ∆t h h Pressure Pressure Pressure Test No. 1 2 Time bottom (cm) top (cm) bottom (psi) top (psi) Cell (psi) 1 12.8 34.5 1:03:00 PM 2.2 0.0 6.3 2 15.5 34.5 1:06:00 PM 2.2 0.0 6.3 3 18.1 34.5 1:09:00 PM 2.2 0.0 6.3 4 20.7 34.5 1:12:00 PM 2.3 0.0 6.3

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -24.4 -21.7 -168.7 -193.1 -190.4 180 2.85 E-05 2 -21.7 -19 -154.7 -176.4 -173.7 180 3.12 E-05 3 -19 -16.4 -154.7 -173.7 -171.1 180 3.05 E-05 4 -16.4 -13.8 -154.7 -171.1 -168.5 180 3.10 E-05 Average Permeability 3.03 E-05

Table A.19: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4%

Lime Mix Sample Cured for 60 Days, 500 ml readings

111

Sample Data Diameter: 7.32 cm Mass: 1039.9 g Height, Lo: 15.34 cm

Area, A: 42.1 cm3 Volume: 645.6 cm3 Initial h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 4.0 34.5 1:00:00 PM 2.4 0.0 6.2 2 7.4 34.5 1:05:00 PM 2.2 0.0 6.2 3 10.8 34.5 1:10:00 PM 2.3 0.0 6.2 4 14.2 34.5 1:15:00 PM 2.4 0.0 6.2 + ∆t h h Pressure Pressure Pressure Test 1 2 Time No. bottom bottom (cm) top (cm) (psi) top (psi) Cell (psi) 1 7.4 34.5 1:05:00 PM 2.2 0.0 6.2 2 10.8 34.5 1:10:00 PM 2.3 0.0 6.2 3 14.2 34.5 1:15:00 PM 2.4 0.0 6.2 4 17.7 34.5 1:20:00 PM 2.4 0.0 6.2

Test ∆h0 ∆h∆t ∆P /γ htot 0 htot∆t ∆t Permeability No. (cm) (cm) (cm) (cm) (cm) (sec) K (cm/s) 1 -30.5 -27.1 -168.7 -199.2 -195.8 300 2.09 E-05 2 -27.1 -23.7 -154.7 -181.8 -178.4 300 2.29 E-05 3 -23.7 -20.3 -161.7 -185.4 -182.0 300 2.25 E-05 4 -20.3 -16.8 -168.7 -189.0 -185.5 300 2.27 E-05 Average Permeability 2.23 E-05

Table A.20: Permeability Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4%

Lime Mix Sample Cured for 90 Days, 500 ml readings

112 Solubility Test

Tests Performed

• 100% FGD Gypsum:

o 7 Days Cured Sample

o 28 Days Cured Sample

o 60 Days Cured Sample

o 90 Days Cured Sample

• 50% FGD Gypsum and 50% Fly Ash

o 7 Days Cured Sample

o 28 Days Cured Sample

o 60 Days Cured Sample

o 90 Days Cured Sample

• 50% FGD Gypsum, 50% Fly Ash, and 2% Lime

o 7 Days Cured Sample

o 28 Days Cured Sample

o 60 Days Cured Sample

o 90 Days Cured Sample

• 50% FGD Gypsum, 50% Fly Ash, and 4% Lime

o 7 Days Cured Sample

o 28 Days Cured Sample

o 60 Days Cured Sample

o 90 Days Cured Sample Examples of data sheets provided 113 Amt. Collected Mass of Dish Mass of Dish & Effluent Mass of Dish & Solids Percent Solids Pore (mL) (g) (g) (g) (%) Volumes 0-100 49.94 111.93 50.21 0.44 0.20 100-200 30.9 85.67 31.06 0.29 0.61 200-300 49.62 104.95 49.8 0.33 1.02 300-400 30.73 83.7 30.86 0.25 1.43 400-500 49.98 103.83 50.11 0.24 1.84 500-600 30.77 84.7 30.91 0.26 2.25 600-700 49.99 103.6 50.15 0.30 2.66 700-800 30.48 83.47 30.62 0.26 3.07 800-900 49.84 105.88 50.01 0.30 3.48 900-1000 30.78 79.39 30.9 0.25 3.89 1000-1100 49.77 105.93 49.92 0.27 4.30

114 1100-1200 30.67 87.33 30.82 0.26 4.71

1200-1300 30.76 89.46 30.92 0.27 5.12

Table A.21: Solubility Data Sheet for 100% FGD Gypsum Sample Cured for 7 Days

114

Amt. Collected Mass of Dish Mass of Dish & Effluent Mass of Dish & Solids Percent Solids Pore (mL) (g) (g) (g) (%) Volumes 0-100 30.75 78.32 30.96 0.44 0.21 100-200 30.44 77.63 30.58 0.30 0.63 200-300 30.78 77.98 30.89 0.23 1.06 300-400 30.51 77.77 30.65 0.30 1.48 400-500 50.15 97.67 50.27 0.25 1.90 500-600 49.96 96.6 50.1 0.30 2.32 600-700 49.64 97.36 49.76 0.25 2.74 700-800 49.87 97.38 49.98 0.23 3.17 800-900 50.01 98.06 50.13 0.25 3.59 900-1000 50.2 97.4 50.32 0.25 4.01 115 1000-1100 49.77 96.24 49.88 0.24 4.43

1100-1200 49.94 96.95 50.06 0.26 4.85

Table A.22: Solubility Data Sheet for 100% FGD Gypsum Sample Cured for 28 Days

115

Amt. Collected Mass of Dish Mass of Dish & Effluent Mass of Dish & Solids Percent Solids Pore (mL) (g) (g) (g) (%) Volumes 0-100 74.8 126.68 75.04 0.46 0.20 100-200 50.04 107.05 50.2 0.28 0.59 200-300 69.16 125.7 69.33 0.30 0.99 300-400 49.88 106.38 50.04 0.28 1.38 400-500 70.94 130.45 71.1 0.27 1.78 500-600 49.81 109.56 49.97 0.27 2.17 600-700 75.22 125.51 75.37 0.30 2.57 700-800 49.68 106.21 49.83 0.27 2.96 800-900 74.35 127 74.49 0.27 3.36 900-1000 50 107.92 50.15 0.26 3.75 116 1000-1100 58.46 114 58.62 0.29 4.15

1100-1200 49.96 99.83 50.1 0.28 4.54 1200-1300 50.14 113.25 50.3 0.25 4.94

Table A.23: Solubility Data Sheet for 100% FGD Gypsum Sample Cured for 60 Days

116

Amt. Collected Mass of Dish Mass of Dish & Effluent Mass of Dish & Solids Percent Solids Pore (mL) (g) (g) (g) (%) Volumes 0-100 74.82 122.45 75.02 0.42 0.21 100-200 69.19 117.05 69.33 0.29 0.62 200-300 70.95 118 71.08 0.28 1.03 300-400 75.25 122.39 75.38 0.28 1.44 400-500 74.35 121.82 74.49 0.29 1.85 500-600 49.74 97.13 49.86 0.25 2.26 600-700 50.03 97.73 50.14 0.23 2.67 700-800 50.01 97.43 50.14 0.27 3.08 800-900 30.81 77.77 30.92 0.23 3.49 117 900-1000 30.81 77.83 30.93 0.26 3.90 1000-1100 30.55 77.93 30.67 0.25 4.31 1100-1200 30.86 78.56 30.97 0.23 4.72

Table A.24: Solubility Data Sheet for 100% FGD Gypsum Sample Cured for 90 Days

117

Amt. Collected Mass of Dish Mass of Dish & Mass of Dish & Solids Percent Solids Pore (mL) (g) Effluent (g) (g) (%) Volumes 0-100 30.44 90.14 30.75 0.52 0.26 100-200 74.81 128.08 75.07 0.49 0.77 200-300 30.81 89.45 31.03 0.38 1.28 300-400 69.17 129.18 69.35 0.30 1.79 400-500 30.52 80.33 30.68 0.32 2.30 500-600 70.93 124.02 71.09 0.30 2.81 600-700 30.96 88.56 31.11 0.26 3.32 700-800 75.24 131.24 75.39 0.27 3.83 800-900 30.68 86.25 30.84 0.29 4.35

118 900-1000 74.35 133.02 74.51 0.27 4.86

Table A.25: Solubility Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix Sample Cured for 7 Days

118

Amt. Collected Mass of Dish Mass of Dish & Mass of Dish & Solids Percent Solids Pore (mL) (g) Effluent (g) (g) (%) Volumes 0-100 74.82 122.21 75.05 0.49 0.24 100-200 69.16 116.86 69.39 0.48 0.73 200-300 70.94 118.33 71.11 0.36 1.22 300-400 75.23 122.65 75.37 0.30 1.71 400-500 74.35 121.59 74.48 0.28 2.19 500-600 58.48 105.64 58.6 0.25 2.68 600-700 30.94 78.4 31.06 0.25 3.17 700-800 30.63 77.83 30.76 0.28 3.66 800-900 30.73 78.38 30.85 0.25 4.15

119 900-1000 30.79 77.88 30.92 0.28 4.63

1000-1100 30.74 77.95 30.87 0.28 5.12

Table A.26: Solubility Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix Sample Cured for 28 Days

119

Amt. Collected Mass of Dish Mass of Dish & Effluent Mass of Dish & Solids Percent Solids Pore (mL) (g) (g) (g) (%) Volumes 0-100 30.76 78.35 31.06 0.63 0.21 100-200 30.91 78.24 31.13 0.46 0.62 200-300 30.44 77.37 30.58 0.30 1.04 300-400 30.63 78.25 30.78 0.31 1.46 400-500 49.95 97.33 50.07 0.25 1.87 500-600 49.85 97.23 49.98 0.27 2.29 600-700 49.65 97 49.78 0.27 2.71 700-800 50 97.13 50.12 0.25 3.12

120 800-900 49.78 97.22 49.91 0.27 3.54 900-1000 50.19 97.83 50.31 0.25 3.96

1000-1100 49.98 97.6 50.09 0.23 4.37 1100-1200 50.14 97.89 50.25 0.23 4.79

Table A.27: Solubility Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix Sample Cured for 60 Days

120

Amt. Collected Mass of Dish Mass of Dish & Effluent Mass of Dish & Solids Percent Solids Pore (mL) (g) (g) (g) (%) Volumes 0-100 74.83 122.68 75.09 0.54 0.22 100-200 69.18 117.04 69.39 0.44 0.66 200-300 70.95 118.67 71.09 0.29 1.10 300-400 75.27 122.98 75.39 0.25 1.55 400-500 74.35 121.76 74.47 0.25 1.99 500-600 58.47 105.73 58.6 0.28 2.43 600-700 30.56 78.74 30.69 0.27 2.87 700-800 30.73 78.51 30.86 0.27 3.31 800-900 30.81 77.54 30.93 0.26 3.75 121 900-1000 30.77 78.54 30.89 0.25 4.19

1000-1100 31.03 78.43 31.15 0.25 4.64 1100-1200 30.88 78.07 31 0.25 5.08

Table A.28: Solubility Data Sheet for 50% FGD Gypsum and 50% Fly Ash Mix Sample Cured for 90 Days

121

Amt. Collected Mass of Dish Mass of Dish & Effluent Mass of Dish & Solids Percent Solids Pore (mL) (g) (g) (g) (%) Volumes 0-100 74.82 122.16 75.1 0.59 0.23 100-200 69.17 116.21 69.4 0.49 0.68 200-300 70.95 118.14 71.16 0.45 1.14 300-400 75.25 122.87 75.46 0.44 1.59 400-500 74.35 121.74 74.55 0.42 2.04 500-600 58.47 105.74 58.67 0.42 2.50 600-700 31.07 77.77 31.27 0.43 2.95 700-800 30.95 78.32 31.15 0.42 3.41 800-900 30.8 77.76 31 0.43 3.86

122 900-1000 30.86 77.25 31.05 0.41 4.32

1000-1100 30.82 77.99 31.02 0.42 4.77

Table A.29: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2% Lime Mix Sample Cured for 7 Days

122

Amt. Collected Mass of Dish Mass of Dish & Effluent Mass of Dish & Solids Percent Solids Pore (mL) (g) (g) (g) (%) Volumes 0-100 74.83 121.89 75.14 0.66 0.23 100-200 69.18 116.29 69.4 0.47 0.68 200-300 70.94 118.26 71.14 0.42 1.14 300-400 75.27 122.78 75.45 0.38 1.59 400-500 74.34 121.45 74.51 0.36 2.04 500-600 58.49 105.42 58.62 0.28 2.50 600-700 30.86 77.8 30.99 0.28 2.95 700-800 30.98 77.14 31.1 0.26 3.41

123 800-900 30.76 78.07 30.88 0.25 3.86 900-1000 31.08 78.21 31.2 0.25 4.32

1000-1100 30.59 77.92 30.71 0.25 4.77

Table A.30: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2% Lime Mix Sample Cured for 28 Days

123

Amt. Collected Mass of Dish Mass of Dish & Mass of Dish & Percent Solids Pore (mL) (g) Effluent (g) Solids (g) (%) Volumes 0-100 74.83 121.89 75.14 0.66 0.22 100-200 69.18 116.66 69.41 0.48 0.66 200-300 70.94 118.27 71.13 0.40 1.11 300-400 75.29 123.15 75.45 0.33 1.55 400-500 74.34 121.56 74.49 0.32 1.99 500-600 58.48 106.4 58.62 0.29 2.43 600-700 30.97 78.35 31.11 0.30 2.88 700-800 30.99 78.5 31.13 0.29 3.32 800-900 30.96 78.3 31.09 0.27 3.76 124 900-1000 31.11 78.82 31.23 0.25 4.20

1000-1100 30.71 77.6 30.83 0.26 4.65 1100-1200 31.25 78.39 31.37 0.25 5.09

Table A.31: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2% Lime Mix Sample Cured for 60 Days

124

Amt. Collected Mass of Dish Mass of Dish & Mass of Dish & Solids Percent Solids Pore (mL) (g) Effluent (g) (g) (%) Volumes 0-100 74.83 122.07 75.13 0.64 0.22 100-200 69.17 116.19 69.39 0.47 0.66 200-300 70.94 118.47 71.11 0.36 1.11 300-400 75.23 122.28 75.39 0.34 1.55 400-500 74.35 121.7 74.48 0.27 1.99 500-600 58.48 105.19 58.61 0.28 2.43 600-700 30.82 77.63 30.94 0.26 2.88 700-800 30.98 77.85 31.1 0.26 3.32

125 800-900 30.76 77.2 30.88 0.26 3.76

900-1000 30.64 77.06 30.76 0.26 4.20 1000-1100 31.16 77.88 31.28 0.26 4.65 1100-1200 30.61 76.57 30.73 0.26 5.09

Table A.32: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 2% Lime Mix Sample Cured for 90 Days

125

Amt. Collected Mass of Dish Mass of Dish & Effluent Mass of Dish & Solids Percent Solids Pore (mL) (g) (g) (g) (%) Volumes 0-100 74.82 122.42 75.05 0.48 0.21 100-200 69.17 116.82 69.4 0.48 0.62 200-300 70.94 118.27 71.15 0.44 1.04 300-400 75.24 122.77 75.46 0.46 1.45 400-500 74.34 122.3 74.55 0.44 1.87 500-600 58.47 105.96 58.67 0.42 2.28 600-700 30.94 78.39 31.19 0.53 2.70 700-800 30.67 77.85 30.93 0.55 3.11 126 800-900 30.58 78.1 30.81 0.48 3.53 900-1000 30.72 77.96 30.96 0.51 3.94 1000-1100 30.67 78.37 30.92 0.52 4.36 1100-1200 30.72 78.3 30.96 0.50 4.77

Table A.33: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4% Lime Mix Sample Cured for 7 Days

126

Amt. Collected Mass of Dish Mass of Dish & Effluent Mass of Dish & Solids Percent Solids Pore (mL) (g) (g) (g) (%) Volumes 0-100 74.82 122.13 75.11 0.61 0.21 100-200 69.17 116.28 69.38 0.45 0.63 200-300 70.94 117.89 71.11 0.36 1.06 300-400 75.24 122.32 75.4 0.34 1.48 400-500 74.35 121.46 74.51 0.34 1.90 500-600 31.03 77.91 31.18 0.32 2.33 600-700 30.71 78.28 30.87 0.34 2.75 700-800 30.84 77.91 30.99 0.32 3.17 127 800-900 30.73 78.05 30.87 0.30 3.60

900-1000 30.73 77.8 30.87 0.30 4.02 1000-1100 30.83 77.85 30.97 0.30 4.44 1100-1200 30.56 77.71 30.7 0.30 4.87

Table A.34: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4% Lime Mix Sample Cured for 28 Days

127

Amt. Collected Mass of Dish Mass of Dish & Mass of Dish & Solids Percent Solids Pore (mL) (g) Effluent (g) (g) (%) Volumes 0-100 30.57 78.08 30.85 0.59 0.21 100-200 31.17 78.3 31.38 0.45 0.62 200-300 31.04 77.47 31.21 0.37 1.04 300-400 30.91 78.14 31.06 0.32 1.45 400-500 30.92 78.1 31.07 0.32 1.87 500-600 30.86 78.44 31 0.29 2.28 600-700 74.83 122.2 74.97 0.30 2.70 700-800 69.19 116 69.33 0.30 3.11 800-900 70.95 117.53 71.08 0.28 3.53 12

8 900-1000 75.27 122.71 75.4 0.27 3.94 1000-1100 74.36 121.9 74.49 0.27 4.36 1100-1200 58.49 105.55 58.62 0.28 4.77

Table A.35: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4% Lime Mix Sample Cured for 60 Days

128

Amt. Collected Mass of Dish Mass of Dish & Effluent Mass of Dish & Solids Percent Solids Pore (mL) (g) (g) (g) (%) Volumes 0-100 74.84 121.69 75.11 0.58 0.20 100-200 69.18 116.12 69.38 0.43 0.61 200-300 70.94 117.5 71.11 0.37 1.02 300-400 75.27 122.48 75.43 0.34 1.43 400-500 74.35 121.04 74.49 0.30 1.84 500-600 58.48 105.14 58.62 0.30 2.25 600-700 31.2 77.67 31.34 0.30 2.66 700-800 30.94 78.37 31.08 0.30 3.07 129 800-900 30.97 78.58 31.11 0.29 3.47

900-1000 30.9 77.88 31.04 0.30 3.88 1000-1100 31.05 78.4 31.19 0.30 4.29 1100-1200 30.65 78.08 30.79 0.30 4.70

Table A.36: Solubility Data Sheet for 50% FGD Gypsum, 50% Fly Ash, and 4% Lime Mix Sample Cured for 90 Days

129 Pore Volume Calculations

Calculations Performed

• 100% FGD Gypsum:

o 7 Days Cured Sample

o 28 Days Cured Sample

o 60 Days Cured Sample

o 90 Days Cured Sample

• 50% FGD Gypsum and 50% Fly Ash

o 7 Days Cured Sample

o 28 Days Cured Sample

o 60 Days Cured Sample

o 90 Days Cured Sample

• 50% FGD Gypsum, 50% Fly Ash, and 2% Lime

o 7 Days Cured Sample

o 28 Days Cured Sample

o 60 Days Cured Sample

o 90 Days Cured Sample

• 50% FGD Gypsum, 50% Fly Ash, and 4% Lime

o 7 Days Cured Sample

o 28 Days Cured Sample

o 60 Days Cured Sample

o 90 Days Cured Sample Examples of data sheets provided

130

Sample: 100 Percent FGD Gypsum (7 days) Date: 26-Jun-09 Tested by: Deepa

Moisture Content 16.4 % Gs : 2.3

Diameter: 2.828 in. 7.18312 cm 2.834 in. 7.19836 cm 2.842 in. 7.21868 cm 2.834666667 in. 7.200053333 cm

Length: 5.96 in. 15.1384 cm 5.975 in. 15.1765 cm 5.977 in. 15.18158 cm 5.970666667 in. 15.16549333 cm

Mass: 999.7 g

Volume : 37.6805038 in3 617.4728273 cm3

Moist Density : 101.07033 pcf 1.619018612 g/cm3

Dry Density : 86.83018038 pcf 1.390909461 g/cm3

Total Porosity : 0.394995956 0.395256756

Pore Volume : 244.0603068 mL

5 Pore Volumes : 1220.301534 mL

Table A.37: Pore Volume Calculation Data Sheet for 100% FGD Gypsum Sample

Cured for 7 Days

131

Sample: 100% Cardinal FGD Gypsum (28 days) Date: 20-Jul-09 Tested by: Deepa

Moisture Content 13.3 % Gs : 2.3

Diameter: 2.826 in. 7.17804 cm 2.824 in. 7.17296 cm 2.818 in. 7.15772 cm 2.822666667 in. 7.169573333 cm

Length: 5.96 in. 15.1384 cm 5.959 in. 15.13586 cm 5.958 in. 15.13332 cm 5.959 in. 15.13586 cm

Mass: 975 g

Volume : 37.28914762 in3 611.0596485 cm3

Moist Density : 99.60768619 pcf 1.595588912 g/cm3

Dry Density : 87.91499223 pcf 1.408286772 g/cm3

Total Porosity : 0.387437345 0.387701404

Pore Volume : 236.9086834 mL

5 Pore Volumes : 1184.543417 mL

Table A.38: Pore Volume Calculation Data Sheet for 100% FGD Gypsum Sample

Cured for 28 Days

132

Sample: 100% Cardinal FGD Gypsum (60 days) Date: 26-Jun-09 Tested by: Deepa

Moisture Content 16.4 % Gs : 2.3

Diameter: 2.841 in. 7.21614 cm 2.846 in. 7.22884 cm 2.835 in. 7.2009 cm 2.840666667 in. 7.215293333 cm

Length: 5.922 in. 15.04188 cm 5.921 in. 15.03934 cm 5.928 in. 15.05712 cm 5.923666667 in. 15.04611333 cm

Mass: 969.1 g

Volume : 37.54231452 in3 615.2083108 cm3

Moist Density : 98.33729142 pcf 1.575238798 g/cm3

Dry Density : 84.48220913 pcf 1.353297936 g/cm3

Total Porosity : 0.411355845 0.411609593

Pore Volume : 253.2256423 mL

5 Pore Volumes : 1266.128212 mL

Table A.39: Pore Volume Calculation Data Sheet for 100% FGD Gypsum Sample

Cured for 60 Days

133

Sample: 100% Cardinal FGD Gypsum (90 days) Date: 28-Jul-09 Tested by: Deepa

Moisture Content 17.1 % Gs : 2.3

Diameter: 2.839 in. 7.21106 cm 2.838 in. 7.20852 cm 2.852 in. 7.24408 cm 2.843 in. 7.22122 cm

Length: 5.927 in. 15.05458 cm 5.926 in. 15.05204 cm 5.928 in. 15.05712 cm 5.927 in. 15.05458 cm

Mass: 1004.7 g

Volume : 37.62517495 in3 616.5661499 cm3

Moist Density : 101.7252033 pcf 1.629508853 g/cm3

Dry Density : 86.87037004 pcf 1.391553248 g/cm3

Total Porosity : 0.394715928 0.394976849

Pore Volume : 243.5293549 mL

5 Pore Volumes : 1217.646774 mL

Table A.40: Pore Volume Calculation Data Sheet for 100% FGD Gypsum Sample

Cured for 90 Days

134

Sample: 50% Cardinal FGD Gypsum & 50% FA Date: 14 Aug. 2009 Tested by: Deepa

Moisture Content 19.3 % Gs : 2.15

Diameter: 2.865 in. 7.2771 cm 2.835 in. 7.2009 cm 2.842 in. 7.21868 cm 2.847333333 in. 7.232226667 cm

Length: 5.982 in. 15.19428 cm 5.973 in. 15.17142 cm 5.982 in. 15.19428 cm 5.979 in. 15.18666 cm

Mass: 1098.5 g

Volume : 38.07106794 in3 623.873027 cm3

Moist Density : 109.9197404 pcf 1.760774953 g/cm3

Dry Density : 92.13725095 pcf 1.475922006 g/cm3

Total Porosity : 0.313228601 0.313524648

Pore Volume : 195.5995713 mL

5 Pore Volumes : 977.9978567 mL

Table A.41: Pore Volume Calculation Data Sheet for 50% FGD Gypsum and 50%

Fly Ash Mix Sample Cured for 7 Days

135

Sample: 50% FGD Gypsum & 50% FA (28 days) Date: 18-Jul-09 Tested by: Deepa

Moisture Content 22.5 % Gs : 2.15

Diameter: 2.833 in. 7.19582 cm 2.843 in. 7.22122 cm 2.837 in. 7.20598 cm 2.837666667 in. 7.207673333 cm

Length: 5.954 in. 15.12316 cm 5.955 in. 15.1257 cm 5.957 in. 15.13078 cm 5.955333333 in. 15.12654667 cm

Mass: 1085.5 g

Volume : 37.66332984 in3 617.1913965 cm3

Moist Density : 109.7948087 pcf 1.758773706 g/cm3

Dry Density : 89.62841527 pcf 1.435733638 g/cm3

Total Porosity : 0.331928926 0.332216913

Pore Volume : 205.0414203 mL

5 Pore Volumes : 1025.207101 mL

Table A.42: Pore Volume Calculation Data Sheet for 50% FGD Gypsum and 50%

Fly Ash Mix Sample Cured for 28 Days

136

Sample: 50% Cardinal FGD Gypsum & 50% FA Date: 17-Jul-09 Tested by: Deepa

Moisture Content 18 % Gs : 2.15

Diameter: 2.856 in. 7.25424 cm 2.86 in. 7.2644 cm 2.864 in. 7.27456 cm 2.86 in. 7.2644 cm

Length: 6 in. 15.24 cm 6.12 in. 15.5448 cm 6.03 in. 15.3162 cm 6.05 in. 15.367 cm

Mass: 1006.6 g

Volume : 38.86666904 in3 636.9105931 cm3

Moist Density : 98.66208659 pcf 1.580441605 g/cm3

Dry Density : 83.61193779 pcf 1.339357292 g/cm3

Total Porosity : 0.376774465 0.37704312

Pore Volume : 240.1427571 mL

5 Pore Volumes : 1200.713785 mL

Table A.43: Pore Volume Calculation Data Sheet for 50% FGD Gypsum and 50%

Fly Ash Mix Sample Cured for 60 Days

137

Sample: 50% Cardinal FGD Gypsum & 50% FA Date: 11 Aug. 2009 Tested by: Deepa

Moisture Content 20.9 % Gs : 2.15

Diameter: 2.856 in. 7.25424 cm 2.864 in. 7.27456 cm 2.859 in. 7.26186 cm 2.859666667 in. 7.263553333 cm

Length: 5.993 in. 15.22222 cm 6.004 in. 15.25016 cm 5.998 in. 15.23492 cm 5.998333333 in. 15.23576667 cm

Mass: 1052.2 g

Volume : 38.5257679 in3 631.3242242 cm3

Moist Density : 104.0441546 pcf 1.666655515 g/cm3

Dry Density : 86.05802699 pcf 1.378540542 g/cm3

Total Porosity : 0.358541838 0.358818353

Pore Volume : 226.5307181 mL

5 Pore Volumes : 1132.653591 mL

Table A.44: Pore Volume Calculation Data Sheet for 50% FGD Gypsum and 50%

Fly Ash Mix Sample Cured for 90 Days

138

Sample: 50% FGD Gypsum, 50% FA, 2% Lime Date: 24-Aug-09 Tested by: Deepa

Moisture Content 19.3 % Gs : 2.12

Diameter: 2.861 in. 7.26694 cm 2.864 in. 7.27456 cm 2.866 in. 7.27964 cm 2.863666667 in. 7.273713333 cm

Length: 6.013 in. 15.27302 cm 6.019 in. 15.28826 cm 6.026 in. 15.30604 cm 6.019333333 in. 15.28910667 cm

Mass: 1049.6 g

Volume : 38.76887546 in3 635.3080434 cm3

Moist Density : 103.1362438 pcf 1.652111934 g/cm3

Dry Density : 86.45116829 pcf 1.384838167 g/cm3

Total Porosity : 0.346184337 0.346466179

Pore Volume : 220.1127501 mL

5 Pore Volumes : 1100.563751 mL

Table A.45: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly

Ash, and 2% Lime Mix Sample Cured for 7 Days

139

Sample: 50% FGD Gypsum, 50% FA, 2% Lime Date: 15 Sep. 2009 Tested by: Deepa

Moisture 19.3 % Content Gs : 2.119

Diameter: 2.865 in. 7.2771 cm 2.865 in. 7.2771 cm 2.863 in. 7.27202 cm 2.864333333 in. 7.275406667 cm

Length: 6.023 in. 15.29842 cm 6.031 in. 15.31874 cm 6.039 in. 15.33906 cm 6.031 in. 15.31874 cm

Mass: 1041.6 g

Volume : 38.86210528 in3 636.8358064 cm3

Moist Density : 102.1046073 pcf 1.635586425 g/cm3

Dry Density : 85.58642694 pcf 1.370986107 g/cm3

Total Porosity : 0.352724231 0.353003253

Pore Volume : 224.8051114 mL

5 Pore Volumes : 1124.025557 mL

Table A.46: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly

Ash, and 2% Lime Mix Sample Cured for 28 Days

140

Sample: 50% FGD Gypsum, 50% FA, 2% Lime Date: 19 Oct. 2009 Tested by: Deepa

Moisture Content 19.3 % Gs : 2.119

Diameter: 2.871 in. 7.29234 cm 2.873 in. 7.29742 cm 2.874 in. 7.29996 cm 2.872666667 in. 7.296573333 cm

Length: 6.035 in. 15.3289 cm 6.035 in. 15.3289 cm 6.033 in. 15.32382 cm 6.034333333 in. 15.32720667 cm

Mass: 1049 g

Volume : 39.110165 in3 640.9007768 cm3

Moist Density : 102.1777964 pcf 1.636758821 g/cm3

Dry Density : 85.64777569 pcf 1.371968836 g/cm3

Total Porosity : 0.352260261 0.352539483

Pore Volume : 225.9428284 mL

5 Pore Volumes : 1129.714142 mL

Table A.47: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly

Ash, and 2% Lime Mix Sample Cured for 60 Days

141

Sample: 50% FGD Gypsum, 50% FA, 2% Lime Date: 20-Nov-09 Tested by: Deepa

Moisture Content 19.3 % Gs : 2.119

Diameter: 2.863 in. 7.27202 cm 2.87 in. 7.2898 cm 2.864 in. 7.27456 cm 2.865666667 in. 7.278793333 cm

Length: 6.026 in. 15.30604 cm 6.028 in. 15.31112 cm 6.013 in. 15.27302 cm 6.022333333 in. 15.29672667 cm

Mass: 1037.3 g

Volume : 38.84239633 in3 636.5128345 cm3

Moist Density : 101.7346874 pcf 1.629660776 g/cm3

Dry Density : 85.27635154 pcf 1.366019092 g/cm3

Total Porosity : 0.355069279 0.35534729

Pore Volume : 226.1831111 mL

5 Pore Volumes : 1130.915555 mL

Table A.48: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly

Ash, and 2% Lime Mix Sample Cured for 90 Days

142

Sample: 50% FGD Gypsum, 50% FA, 4% Lime Date: 10-Dec-09 Tested by: Deepa

Moisture Content 23.2 % Gs : 2.174

Diameter: 2.886 in. 7.33044 cm 2.863 in. 7.27202 cm 2.876 in. 7.30504 cm 2.875 in. 7.3025 cm

Length: 6.028 in. 15.31112 cm 6.014 in. 15.27556 cm 6.022 in. 15.29588 cm 6.021333333 in. 15.29418667 cm

Mass: 1070.6 g

Volume : 39.08933204 in3 640.5593859 cm3

Moist Density : 104.3373211 pcf 1.671351671 g/cm3

Dry Density : 84.68938404 pcf 1.356616616 g/cm3

Total Porosity : 0.375712205 0.375981317

Pore Volume : 240.8383617 mL

5 Pore Volumes : 1204.191809 mL

Table A.49: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly

Ash, and 4% Lime Mix Sample Cured for 7 Days

143

Sample: 50% FGD Gypsum, 50% FA, 4% Lime Date: 29-Jul-09 Tested by: Deepa

Moisture Content 19.3 % Gs : 2.174

Diameter: 2.878 in. 7.31012 cm 2.875 in. 7.3025 cm 2.878 in. 7.31012 cm 2.877 in. 7.30758 cm

Length: 6.037 in. 15.33398 cm 6.032 in. 15.32128 cm 6.031 in. 15.31874 cm 6.033333333 in. 15.32466667 cm

Mass: 1053.9 g

Volume : 39.22174622 in3 642.7292655 cm3

Moist Density : 102.3630391 pcf 1.639726175 g/cm3

Dry Density : 85.8030504 pcf 1.37445614 g/cm3

Total Porosity : 0.367502813 0.367775465

Pore Volume : 236.3800542 mL

5 Pore Volumes : 1181.900271 mL

Table A.50: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly

Ash, and 4% Lime Mix Sample Cured for 28 Days

144

Sample: 50% FGD Gypsum, 50% FA, 4% Lime Date: 26-Aug-09 Tested by: Deepa

Moisture Content 19.3 % Gs : 2.174

Diameter: 2.879 in. 7.31266 cm 2.876 in. 7.30504 cm 2.882 in. 7.32028 cm 2.879 in. 7.31266 cm

Length: 6.025 in. 15.3035 cm 6.017 in. 15.28318 cm 6.023 in. 15.29842 cm 6.021666667 in. 15.29503333 cm

Mass: 1034.7 g

Volume : 39.20034798 in3 642.3786112 cm3

Moist Density : 100.5530432 pcf 1.610732334 g/cm3

Dry Density : 84.28587027 pcf 1.350152837 g/cm3

Total Porosity : 0.378686706 0.378954537

Pore Volume : 243.4322891 mL

5 Pore Volumes : 1217.161446 mL

Table A.51: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly

Ash, and 4% Lime Mix Sample Cured for 60 Days

145

Sample: 50% FGD Gypsum, 50% FA, 4% Lime Date: 30-Sep-09 Tested by: Deepa

Moisture Content 19.3 % Gs : 2.174

Diameter: 2.886 in. 7.33044 cm 2.878 in. 7.31012 cm 2.882 in. 7.32028 cm 2.882 in. 7.32028 cm

Length: 6.027 in. 15.30858 cm 6.032 in. 15.32128 cm 6.048 in. 15.36192 cm 6.035666667 in. 15.33059333 cm

Mass: 1039.9 g

Volume : 39.37341471 in3 645.2146668 cm3

Moist Density : 100.6141794 pcf 1.611711657 g/cm3

Dry Density : 84.33711597 pcf 1.350973728 g/cm3

Total Porosity : 0.378308949 0.378576942

Pore Volume : 244.2633955 mL

5 Pore Volumes : 1221.316978 mL

Table A.52: Pore Volume Calculation Data Sheet for 50% FGD Gypsum, 50% Fly

Ash, and 4% Lime Mix Sample Cured for 90 Days

146