A FIELD CONSOLIDATSON STUDY OF HIGH ASH PAPERMU. SLUDGE Thesis. for the Degree of Ph. D. MICHIGAN STATE UNWERSSTY ROBERT P. VALLEE 1973 we ‘ l mum; Winn Lm (in l 11mm it ill I This is to certify that the thesis entitled A FIELD CONSOLIDATION STUDY OF HIGH ASH PAPERMILL SLUDGE presented by Robert P. Vallee has been accepted towards fulfillment of the requirements for Ph.D. degree in givil Engineering (3 - \‘%)_ (KR ,\,\_&‘x~_'/‘L'QR A ’r‘g ~. Major professor Date \‘s m \\“\'\K 0-7639 ABSTRACT A FIELD CONSOLIDATION STUDY OF HIGH ASH PAPERMILL SLUDGE By Robert P. Vallee An experimental papermill sludge landfill was constructed and monitored to obtain engineering information essential to the development of guidelines and recommendations for the design and operation of solid papermill waste landfills. Papermill sludge is an organic clay material consisting of 32 to 59% kaolinite and having an initial water content of about 260%. The non-clay fraction is primarily organic cellulose fibers. The experimental landfill consisted of 2 sludge layers, each initially 10 ft. thick, with sand drainage blankets at the tOp, middle, and bottom. An earth dike provided lateral confinement of the soft sludge both during and after construction. A surface load, consisting of 3 ft. of natural soil, was placed immediately after construction. The landfill was instrumented with 32 settlement plates, 16 piezometers, 3 total pressure cells, and 10 thermistors. Field data obtained during the first year included settlements, pore water pressures, vertical and lat- eral earth pressures, temperatures, sludge unit weights, specific gravities, and water contents. Laboratory work included consistency limits, ash contents, and consolidation tests run on both fresh and undisturbed samples of sludge. A detailed description of the field Robert P. Vallee behavior is given in the thesis along with predictions based on labo— ratory results and soil mechanics theory. For each sludge layer the ultimate settlement, time-rate of settlement, and'pore pressure dissi- pation are discussed in detail. Several theories that include secondary compression throughout the consolidation process are included in the analyses, along with Terzaghi's theory. The lower sludge layer was loaded gradually (by the upper layer) with time, and its consolidation behavior is modeled using a computer program to account for the slow loading. Pore pressures generated during construction and those existing at the end of primary compression (residual) are analyzed and discussed. Laboratory consolidation data from the undisturbed samples are discussed in detail. It is shown that soil mechanics theory can be used to accu— rately model the sludge consolidation behavior for different conditions of loading. Ultimate primary settlements can be reasonably estimated if appropriate pore pressure changes and void ratio considerations are included in the settlement analysis. Secondary compression is difficult to predict from laboratory parameters. The hydrodynamic portion of the time-settlement relation is accurately modeled by Terzaghi's (1943) theory, Gibson and Lo's (1961) theory, and Wahls's (1962) theory, when a representative value for the coefficient of consolidation is used. Laboratory consolidation tests underestimated this parameter by a factor of four or more. Consolidation theory can be used to predict pore pressures up to about 70 percent dissipation. Residual pore pressures were observed in the sludge at the completion of primary compression. Pore pressures generated during construction were in general agreement Robert P. Vallee with predicted values based on Gibson's (1958) theory. The coefficient of lateral stress decreased from an initial value close to 0.65 imme- diately after sludge placement to about 0.32 for the final stages of consolidation. A FIELD CONSOLIDATION STUDY OF HIGH ASH PAPERMILL SLUDGE By Robert Pf Vallee A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Civil Engineering 1973 To Lindsa who helped me discover the joy of learning ii ACKNOWLEDGEMENTS The writer wishes to express his appreciation to his major professor, Dr. 0. B. Andersland, Professor of Civil Engineering, whose initiative and hard work resulted in the realization of this project, and who provided valuable guidance during the preparation of this thesis. Thanks go also to the members of the writer's doctoral committee: Dr. R. R. Goughnour, former Professor of Civil Engineering; Dr. w. A. Bradley, Professor of Metallurgy, Mechanics, and Materials Science; and to Dr. M. M. Mortland, Professor of Soil Science. The writer also owes his appreciation to: Dr. John M. Paloorthekkathil for performing the Atterberg Limit tests; Mr. Wayne A. Charlie for obtaining the undis— turbed sludge samples; Mr. Tom Danis Sr. of the B. G. Danis 00., Dayton, Ohio for his help and cooperation during construction of the landfill; and to my wife, Lindsa, who helped type the manuscript and gave me encouragement throughout my graduate work. Special appreciation is also given to my parents and Lindsa's parents for their continuing support and interest in my work. Thanks are also due to the U. S. Environmental Protection Agency and the National Council of the Paper Industry for Air and Stream Improvement, Inc. for their financial assistance and cooperation which made this research possible. iii TABLE OF CONTENTS Page DEDICATION . . O O O O O O O O O O C O C O C 0 ii ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . iii LIST OF TABLES . O O O O O O O O . O C O . O . Vii LIST OF FIGURES . . . . . . . . . . . . . . . . viii LIST OF SYMBOLS O O O O C O C C C . C O . . O C Xii Chapter I. INTRODUCTION . . . . . . . . . . . . . . . 1 1.1 Need For Study . . . . . . . . . . . . l 1.2 Objectives of Study . . . . . . . . . . 2 II. PAPERMILL SLUDGE LANDFILLS-r LITERATURE REVIEW . . . . . . . . . . . . . 5 2.1 Current Practice . . . . . . . . . . . 5 2.2 Consolidation Theory . . . . . . . . . . 7 III. EVALUATION OF SLUDGE ENGINEERING CHARACTERISTICS . . . . . . . . . . . . . . 25 3.1 Physical Properties . . . . . . . . . . 25 3.1.1 Water Content . . . . . . . . . . 25 3.1.2 Unit weight 0 O O O I C C C C O 27 3.1.3 Specific Gravity . . . . . . . . . 28 3.1.4 Ash Content, Organic Content . . . . . 28 3.1.5 Consistency Limits . . . . . . . . 29 3.2 Stress-deformation Characteristics . . . . . 30 3.2.1 Consolidation Behavior . . . . . . . 30 3.2.2 Undrained Shear Strength . . . . . . 33 iv Chapter IV. CONSTRUCTION, INSTRUMENTATION AND PIONITORING O O O O O C O O O O O O O 4.1 Construction of the Experimental Landfill . 4.2 4.1.1 Site Preparation and Dike Construction 4.1.2 Sludge Placement . . . . . . . 4.1.3 Drainage Blanket Placement . . . . 4.1.4 Earth Surcharge Placement . . . . Instrumentation and Monitoring . . . . . 4.2.1 Settlement Plates . . . . . . . 4.2.2 Piezometers . . . . . . . . . 4.2.3 Total Pressure Cells . . . . . . 4.2.4 Temperature Sensors . . . . . . 4.2.5 Vane Shear Tests . . . . . . . V. EXPERIMENTAL RESULTS . . . . . . . . . . . 5.1 Physical Properties of the Papermill Sludge . 5. 5. 2 3 Stress-deformation Behavior of the Sludge . 5.2.1 Laboratory Consolidation . . . . . 5.2.2 In-place Vane Shear Tests . . . . Field Monitoring . . . . . . . . . . 5 3.1 Settlement . . . . . . . . . 5.3.2 Pore Water Pressures . . . . . . 5 3.3 Temperature . . . . . . . . . 5 3 4 Lateral Sludge Pressures . . . . . VI. DISCUSSION AND INTERPRETATION OF RESULTS . . . . 6.1 Sludge Placement . . . . . . . . . . 6.2 Engineering Characteristics of the 6. 3 Papermill Sludge . . . . . . . . . . 6.2.1 Physical Properties . . . . . . 6. 2. 2 Consolidation Behavior . . . . . 6. 2. 3 Undrained Shear Strength . . . . . 6. 2. 4 Stress State in the Sludge . . . . 6. 2. 5 Temperature . . . . . . . . Settlement Behavior of the Landfill . . . 6.3.1 Upper Sludge Layer . . . . . . . 6.3.1.1 Loading and Field Observations 6.3.1.2 Ultimate Settlement . . . 6.3.1.3 Time-rate of Settlement . . 6.3.1. 4 Pore Pressure Dissipation . 6.3.2 Lower Sludge Layer . . . . . . . 6.3.2.1 Loading and Field Observations 6.3.2.2 Ultimate Settlement . . . 6.3.2.3 Time-rate of Settlement . . 6. 3. 2. 4 Pore Pressure Dissipation . Page 38 38 38 40 41 42 43 43 45 46 47 47 58 58 59 59 61 62 62 63 64 64 105 105 106 106 108 113 114 115 116 117 117 120 124 128 133 133 134 135 139 Chapter Page VII. SUMMARY AND CONCLUSIONS . . . . . . . . . . . 163 7.1 Field Consolidation . . . . . . . . . . 163 7.1.1 Settlement . . . . . . . . . . . 154 7.1.2 Pore Pressures . . . . . . . . . 165 7.1.3 Stress and Temperature Conditions . . . 166 REFERENCES . . . . . . . . . . . . . . . . . . 168 APPENDICES . . . . . . . . . . . . . . . . . . 172 A. Settlement Data . . . . . . . . . . . . . . 173 B. Piezometer Data . . . . . . . . . . . . . . 177 , C. Pressure Cell Data . . . . . . . . . . . . . 179 D. Temperature Data . . . . . . . . . . . . . 180 E. Vane Shear Strength Data . . . . . . . . . . . 181 F. Consolidation Data . . . . . . . . . . . . . 183 C. Computer program for load increasing linearly with time followed by an instantaneous surcharge application . . . . . . . . . . . . . . . 204 H. Computer program for the solution to the equations in the theory of Gibson and Lo (1961) . . . 207 vi LIST OF TABLES Table 5.1 Physical properties of the papermill sludge . . . 5.2 Sludge placement water contents . . . . . . . 5.3 Summary of consolidation characteristics, fresh sludge 5.4 Summary of consolidation characteristics, undisturbed samples . . . . . . . . . . . . . 6.1 Comparison of actual and calculated settlements . A-l Settlement plate elevations at the bottom sand blanket A-2 Settlement plate elevations at the midpoints of the lower and upper sludge layers . . . . . . . A—3 Settlement plate elevations at the middle sand blanket A-4 Settlement plate elevations at the top sand blanket . B-l Pore water pressures for the bottom sand blanket and lower sludge layer . . . . . . . . . . . B-2 Pore water pressures for the middle sand blanket and upper sludge layer . . . . . . . . . . . C-l Total pressure cell data . . . . . . . . . . D-l Temperature data for the papermill sludge landfill . E-l Undisturbed vane shear strengths . . . . . . . E-2 Remolded vane shear strengths . . . . . . . F-l to 7 Conventional consolidation data . . . . . . . F-8 to 12 Bishop consolidation data . . . . . . . . . F-13 & 14 Single increment Bishop consolidation data . . . . F—lS to 19 Undisturbed sample consolidation data . . . . . vii Page 66 67 68 71 141 173 174 175 176 177 178 179 180 181 182 183 190 195 198 LIST OF FIGURES The settlement problem: (a) Section through a sludge landfill (b) Volume-void ratio relationships Models for the consolidation process: (a) Gibson and Lo (1961) (b) Wahls (1962) . . . . . . . . . Void ratio - effective stress relationships for a normally consolidated clay . . . . . Time—compression curves: (a) Primary and secondary compression (b) Definitions . . . . . . . (a) Consolidation machine and recorder (b) Fixed ring consolidation unit and sludge sample . Vane shear apparatus . . . . . . . . . . . Pre-construction map of existing gravel pit area including dike layout Experimental landfill and instrument group locations, plan view . . . . . Section of landfill (typical), north dike at end of construction . . . . . Sludge placement: (a) Dragline operation (b) Dumping over the dike sides . . . . . . . . . . . . Experimental sludge landfill during placement of the lower sludge layer . . . . . . . . . . . . Settlement plate: (a) Installation in a sand blanket (b) Placement in the sludge, carpenters level shown on plate 0 O O O O O O O O C O O O O O 0 Distribution of settlement plates, piezometers, and total pressure cells in the instrument groups. . Piezometer: (a) Pore pressure transducer (b) Installation in a small sand pocket in the sludge viii Page 22 23 24 35 36 37 50 51 52 53 54 55 56 57 Figure 5.1 Water contents of the sludge in the landfill at the end of consolidation . . . . . . . . . . . . 5.2 Consolidation characteristics for sludge sample U-S: (a) Void ratio (b) Coefficient of consolidation, cv (c) Primary compression ratio, r . . . . . . . (a) Load increment 0.1—0.2 kg/cm (b) Load increment 5.3 Compression dial reading versus logarithm of time: 0.4—0.8 kg/cm2 . . . . . . 5.4 Coefficient of secondary compression, C : (a) C _ _ a a versus log p (b) Ca/Ap versus log p . . . . . . 5.5 Void ratio—effective stress relationships, undisturbed sludge samples . . . . . . . . . . . . . 5.6 Consolidation characteristics for the undisturbed sludge samples: (a) Coefficient of consolidation, c (b) Primary compression ratio, r (c) Coefficignt of secondary compression, Ca . . . . . . . . . . 5.7 Vane shear strengths of the sludge in the landfill: (a) After completion of each sludge layer and after partial consolidation, hand driven vane test (b) Immediately prior to slope excavation, vane test run with pre-augered hole . . . . . . . . . . 5.8 Settlement—time curves: (a) Group 1 (b) Group 2 (c) Group 3 (d) Group 4 (e) Group 5 (f) Group 6 (g) Group 7 (h) Group 8 . . . . . . . . . . 5.9 Settlement versus square root of time curves, upper sludge layer: (a) Groups 1 through 4 (b) Groups 5 through 8 . . . . . . . . . . . . . 5.10 Settlement-logarithm of time curves, upper sludge layer: (a) Groups 1 through 3 and 7 (b) Groups 4 through 6 and 8 . . . . . . . . . . . . . 5.11 Settlement-logarithm of time curves, lower sludge layer after surcharge placement: (a) Groups 1, 2, 3, and 4 (b) Groups 5, 6, 7, and 8 . . . . . . . . . . 5.12 Pore pressure versus time curves: (a) Group 5, piezometers 3 and 6 (b) Group 5, piezometers 2 and 7 (c) Group 5, piezometers 4 and 8 (d) Group 6 (e) Group 7, piezometers 3 and 6 (f) Group 7, piezometers 4 and 7 (g) Group 5, piezometers 5 . . ix Page 73 74 75 76 77 78 79 81 89 91 93 95 Figure 5.13 Temperature versus time: (a) Thermistors l, 3, 5, 7, and 9 (b) Thermistors 2, 4, 6, 8, and 0 . . . . . 5.14 Horizontal and vertical total stresses, lower sludge 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 layer . . . . . . . . . . . . . . . . . Typical stress-strain curves for papermill sludge at 43% and 50% organic contents (Andersland and Laza, 1971). . Comparison between the measured leachate flow rate and the flow rate calculated from time—settlement curves. Estimated effective stress changes and strain distribution in the upper sludge layer: (a) initial stresses (b) Final stresses (0) Strain distribution . Parameter determination for the method of Gibson and Lo . Measured residual excess pore pressures versus depth Comparison of actual and predicted time-settlement curves, upper sludge layer: (a) Terzaghi (1943) theory, settlement vs. time (b) Terzaghi (1943) theory, settlement vs. logarithm of time (c) Theory of Gibson and Lo (1961), settlement vs. logarithm of time (d) Wahls's (1962) theory, settlement vs. logarithm of time . . . . . . . . . . . . . Pore pressure increase due to application of the upper sand blanket and surcharge: (a) Group 5, upper layer (b) Groups 6 and 7, upper layer (c) Group 5, lower layer (d) Groups 6 and 7, lower layer . . . . Comparison of measured and predicted initial pore pressures, upper sludge layer . . . . . . . . . Comparison of measured and predicted pore pressure, mid—point of upper sludge layer: (a) Terzaghi's (1943) theory (b) Theory of Gibson and Lo (1961) . . . 6.10 Theoretical final pore pressure distribution at the end of consolidation if a threshold gradient exists . . . 6.11 Comparison of initial, maximum, and residual pore -pressures, upper sludge layer . . . . . . . . . 6.12 Estimated effective stress changes and strain distri- bution in the lower sludge layer: (a) Initial stresses (b) Final stresses (c) Strain distribution . . Page 102 104 142 143 144 145 146 147 151 152 153 155 155 156 Figure 6.13 6.14 6.15 6.16 6.17 Load increasing linearly with time followed by an instantaneous surcharge application . . . . . Estimates of ultimate settlement of the lower sludge layer for different elevations of the upper sludge layer . . . . . . . . . . . . . . Comparison between the predicted and measured time- settlement curves, lower sludge layer: (a) Finite difference solution (b) Terzaghi procedure for a linearly increasing load . . . . . . . . . Comparison between predicted and measured pore pressures at the mid-point of the lower sludge layer . . . . . . . . . . . . . . . Measured and estimated initial excess pore pressures in the lower sludge layer . . . . . . . . xi Page 157 158 159 161 162 LIST OF SYMBOLS Primary Compressibility of the soil skeleton, inZ/lb Coefficient of compressibility Secondary compressibility of the soil skeleton, inZ/lb Distance to the mid-point of a doubly drained clay layer at t = 0 Compression index Coefficient of consolidation Coefficient of secondary compression (1 + eO)/(l + e)°cv Total oedometer compression for an increment of load Initial compression in oedometer for an increment of load Primary compression in oedometer for an increment of load Secondary compression in oedometer for an increment of load Void ratio Specific gravity of the soil solids Thickness of sludge layer or sample Thickness of sludge layer or sample at the end of primary consolidation Hydraulic gradient Threshold hydraulic gradient Coefficient of permeability Ratio of horizontal effective stress to vertical effective stress Liquid limit xii Ql l/A ll Coefficient Of volume compressibility Pressure Effective pressure Plastic limit Applied surface load Leachate flow rate from drain pipe Primary compression ratio, dp/D Settlement as a function of time Time Time assumed for the end of primary compression Time of surcharge application Time factor Excess hydrostatic pore pressure Percent consolidation Residual excess pore pressure Nominal flow rate of pore fluid Volume Water content Depth to a point in a soil layer Unit weight of water Dry unit weight Increment Settlement at time t l Settlement at time t2 Strain at a point Effective normal stress . . . . 2 Viscosity of the 8011 structure, lb-sec/In xiii CHAPTER I INTRODUCTION 1.1 Need for Study Solid wastes resulting from the pulp or paper making process are removed from effluent streams by treatment devices designed to protect the nation's surface water resources. An estimated 2,500,000 dry tons of solid residue are removed annually (Gillespie, Gellman, and Janes, 1970) giving a sludge cake volume close to 200 million cubic yards. The great majority of these sludges are disposed of on land. A survey (Gillespie, 1969) by the National Council of the Paper Industry for Air and Stream Improvement, Inc., indicated that more than 1100 acres of land are in use as sludge depositories. Sludge disposal on land, in most cases, lacks long range planning, hence it is achieved on a temporary rather than a permanent basis. Thorough planning would include the application of sound engineering principles to all stages of site selection, design, Operation, and completed use of the landfill. To facilitate this planning, it is essential to have an under- standing of the many variables that will affect landfill volume change, settlement, slope stability and bearing capacity. In anticipation of the industry's need for information on satisfactory disposal practices, the National Council of the Paper Industry for Air and Stream Improvement conducted both a questionnaire survey of current land disposal practices (Gillespie, 1969) and a core sampling investigation of existing sludge deposits (Gillespie, Mazzola, and Gellman, 1970). The core sampling program showed that in situ sludge water contents were higher than those normally encountered in clay soils, with large variations occurring in the vertical direction. These high water contents suggest that large settlements can be expected under surface loads. Field vane shear strengths ranged from 0.12 to 0.37 kg/cm2 indicating low in—situ sludge stability. Experimental laboratory data (Andersland and Laza, 1971; Andersland and Paloorthekkathil, 1972) have demonstrated the influence of a number of variables on the shear strength, permeability, and consolidation behavior of papermill sludge. The task remained to verify, with field observations, the accuracy of predictions (based on laboratory data) of settlement, drainage, and stability for a constructed landfill. 1.2 Objectives of Study The general objective of the study is to contribute--through field observations on an experimental landfill, laboratory work, and analysis--basic information, relative to the sludge behavior, which is needed for developing guidelines and recommendations for the design and operation of solid papermill waste landfills. It is desirable that the completed sludge landfill be stable and have the potential for a number of uses, including use as a recreational area or as a foundation for light construction. Pursuant to this general objective the research program was directed at the consolidation behavior of the landfill. Specific items relative to consolidation behavior include: 1. Dewatered pulp and papermill sludges from different mills may have consistencies which require different placement techniques. Effectiveness of placement methods used at the experimental site will be summarized. 2. Consolidation parameters, which include the compression index, coef- ficient of consolidation, and coefficient of secondary compression, are useful in prediction of settlement in soils. Comparisons will be made between the observed field behavior and predictions based on these exper- imental sludge parameters. These predictions have implications relative to landfill capacity, settlement of future structures built on the land— fill, and flow rate and volume of drainage effluent. Various theories used to mathematically model the consolidating sludge will be reviewed and their application to the sludge landfill discussed. The laboratory parameters will be determined for both fresh sludge samples and for undisturbed samples obtained from the landfill at the completion of consolidation. 3. Surcharge loads used in combination with drainage blankets are an effective means for improving the drainage of certain peat and clay soils. Use of this method in the experimental sludge landfill will be evaluated as to its potential for obtaining better sludge drainage. This should result in increased sludge shear strength and improved landfill stability. In—situ vane shear tests will be run to determine the increase in shear strength with consolidation. 4. The magnitude of effective lateral stresses has implications relative to stability analyses involving bearing capacity and slope stability. The observed change in lateral stresses during sludge placement, surcharge loading, and consolidation will provide insight as to the actual stress distribution existing in the sludge. The field research site was selected in collaboration with the National Council of the Paper Industry for Air and Stream Improvement, Inc., and the host papermill. The experimental landfill site, the dewatered sludge (including hauling to the site), and field laboratory space were provided by the host papermill. A local contractor constructed the earth dikes and placed the dewatered papermill sludge and sand drainage blankets during the summer and fall of 1971. The author supervised construction of the landfill, took initial sludge samples, installed instrumentation, and initiated field monitoring of the landfill. Physical properties and certain stress-deformation charac- teristics of the sludge were obtained using the soil mechanics labora- tory facilities at Michigan State University. CHAPTER II LITERATURE REVIEW Information directly oriented to the design and operation of papermill sludge landfills is very limited. Most of the literature concerns the separation and concentration of solids from the papermill waste, with very limited planning and application of engineering prin— ciples to disposal of the sludge cake on land. Current practices depend on land available, haul distance, nuisance condition, and local require- ments for sanitary landfills. Settlement data for these sludge land- fills is essentially nonexistent except for some laboratory research. 2.1 Current Practice Sludge disposal procedures followed at a particular mill are dependent, to some extent, on the quantity and nature of the sludge produced. Sludge removed from a primary clarifier may range from 1 to 15 percent solids by weight and have an ash content as high as 70 per- cent. This low consistency undewatered sludge is in some cases pumped to earthen basins, lagoons, or drying beds for natural dewatering. The earthen basins or drying beds require adjacent soils which are rela- tively permeable, such as sands or gravels. After dewatering by natural drainage, the sludge cake may be covered with soil and left in place hidefinitely, or may be excavated and hauled to some more distant land— fill. Gillespie (1969) states that data available for drying beds are U1 too erratic to allow meaningful conclusions to be drawn on the perfor— mance of this type of dewatering. In some cases long pipelines have been constructed to transport these fluid sludges to large abandoned pits, especially when the calculated use period exceeds five years. The life of these pits was usually extended by the construction of dikes to retain more sludge. Very often, odors emanating from the lagoons or drying beds during warm weather have become a nuisance to local residents and prop- erty owners. The practice of pumping clarifier sludge to earthen basins is limited to smaller mills where the volume of sludge production is low and where land is available. In most instances this practice lacks long range planning and solves the disposal problem on a temporary rather than a permanent basis. More recent disposal developments (Follet and Gehm, 1966) include the dewatering of the clarifier sludge by means of centrifu- gation, vacuum filtration, or mechanical pressing. The resulting sludge cake may have a solids content as high as 40 percent (equivalent to 150 percent water content) for the high ash sludges. The dewatered sludge is hauled by truck to the disposal site, in some cases as far as five miles from the mill. The disposal sites often are abandoned gravel pits, low lying areas, or other such lands depreciated through use. The sludge is dumped at the site and distributed with suitable earth moving equipment. In a few instances, a cell type of landfill with individual compartments separated horizontally and vertically with a porous material has been used. The resulting slow drainage has helped to decrease the \“Dlume occupied by the residue. Limited information on sludge stability and sludge drainability has hindered the development of this approach to OI‘ganized landfill Operations. This project is intended to provide information relative to the field consolidation of dewatered sludge so that the necessary guidelines and recommendations for the design and operation of papermill sludge landfills can be developed. 2.2 Consolidation Theory Natural drainage of water from sludge deposits results in a decrease in volume with an accompanying settlement of the surface. This volume change may occur almost entirely in the vertical direction, approximating one—dimensional compression. The application of surface loads from additional sludge, soil cover, or construction serves to increase this volume change or settlement. This phenomenon has been observed for existing sludge deposits containing high in—situ water contents. For organized landfill operations it is desirable to predict this volume change so as to permit the estimation of total sludge capacity of a landfill and to predict the settlement of any constructed facilities placed on the sludge landfill. Very little published information is available regarding the settlement of papermill sludge landfills. Accordingly, one goes to related areas, such as soil mechanics, and borrows those theories which appear to describe the sludge behavior. Consolidation theory involves the development of an equation from which pressure and void ratio values may be computed at any point and time in a stratum of consolidating material. From such an equation the change in overall thickness of the Strata after any interval of time may be determined by integration or numerical computation. To illustrate the application of certain consoli- e (x -x e n=odd l 2 l 2 (2.6) n n c v a + b l 1 4H2 where H = thickness of the soil layer, K = ll - fl + 2 ~ x (a + K ) __\d[01-+ K ) - 48K c = -£?3 1 = l l 1'1 a = (l-+-l)A, and v ayw x2 2 a b 8 = %-. The pore pressure is given by the expression x x -4 X_e___£ x<_e___l) a+b 1 l a+b K2 -xlt 2 a+b Kl —x2t . nnZ a qo I; x -x e - x -x e Sln 2H 1 2 l 2 n=odd alb- (2.7) For a soil which is infinitely viscous (A+0) or exhibits no secondary compression (b+0) the above equations reduce to those of the classical solution of Terzaghi. These equations have been programmed for solution by computer and the program is given in appendix H. The program assumes that the soil layer is doubly drained and solves for the settlement and pore pressures (at the eighth points of the layer) for each specified time. The thickness of the layer is adjusted after each settlement compu- tation to maintain the appropriate length of drainage path. For large values of time the settlement becomes A —t S(t) = qu [a + b (l - eb )] t Z ta (2.8) and in the limit t+0, the ultimate settlement of the layer is given as Sult = (a + b)qOH (2-9) To determine the parameters a, b, and A it is necessary to plot a graph , where 5 and O are the settlements at times of log10(6 2 1 - 61) vs. t 2 1 t2 and t1, respectively, and t2 - t1 = At = constant. Using equation 12 2.8 the following expression is derived, _ .A log(O2 - Ol) — log I - .434 b tl (2.10) where I = qOHb(1 - e b ). The intercept of the graph represents log I, thus —4 b = I x lO—A (2.11) TA t qOH(l - e ) The lepe of the line is given by .434 %n The value of a can be found from S(t ) :—t a = a - b(1 - e b a qo ) . (2.12) where C(ta) represents the strain at time t = ta. Figure 6.4 shows a plot of log (52 - 61) vs tl for papermill sludge. The rheological model proposed by Wahls (1962) for the analysis of primary and secondary consolidation is shown in Figure 2.2b. Here primary compression is represented by the Kelvin elements and secondary compression is represented by the secondary dashpots. The time dependent transfer of stress from the pore fluid to the soil skeleton is mathematically modeled by the transfer of stress from the viscous dashpot to the Hookean spring in the Kelvin element. Thus, for an increment of load, Ap, we can write for the nth element, 13 4P =‘A:+'5‘t—— (2.13) where Rn is the compression of the nth Kelvin body, An is the spring constant for the nth elastic spring, and Bn is the dashpot constant for the nth viscous dashpot. By solving equation 2.13 for Rn and summing over all the elements to obtain the total primary compression, R1, at time t, Wahls (1962) arrived at A — = a- n Rl —. E Rn Ap An(1 e ) (2.14) n=0 n=0 Since the Terzaghi solution for primary compression provides a good representation of the hydrodynamic effect, Wahls (1962) chose his constants An and Bn to make equation 2.14 identical to the Terzaghi equation, arriving at the following deformation equation of the rheological model for primary compression, R1 = ApAp f(Tv) (2.15) 00 2 8 1 2n + l where f(Tv) = 1 —';f E -————————§ exp {—-£——————11} T 2 v ’ n=0 (2n + 1) 00 Ct A = E A = coefficient of compressibility, T = —X—-, and c = p n v H2 v n=0 coefficient of consolidation. Certain assumptions made by Wahls (1962) concerning secondary compression lead to its representation by the viscous dashpots linked 14 in series with each Kelvin body as shown in Figure 2.2b. The defor- mation equation of the nth secondary dashpot is assumed to be ____= (p0 + AP) (2.16) where Rn is the compression of the nth secondary dashpot and Cn is the dashpot constant of the nth secondary dashpot. Solving this equation for Rn and summing to determine the total secondary deformation, Wahls (1962) arrives at the equation R2 - :E:: Rn — Ca h(T) (2.17) n=0 where 2n + l 2 h(T) = 1.08516'—- :E:: 2 loglo [1 + (-——§--n) TV] for TV 5 7 (2n + 1) n=0 and h(T) = .8353 + loglOTv for Tv > 7 and CO = AH/Hp//Alogt = strain per cycle log time. Thus the total compression, RT’ caused by a pressure increment, Ap, is RT = R1 + R2 = ApAp f(Tv) + canp h(TV) (2.18) where ApAp = AHp total estimated primary compression, and Hp = thickness of the layer at the end of primary compression. Wahls (1962) has determined values of the functions f(Tv) and h(Tv) for different values of Tv and these have been used to determine theoretical 15 time-settlement curves for the papermill sludge. It should be noted that AHp represents primary compression only, and any estimate of primary compression based on field piezometer readings or laboratory CC values must have the appropriate theoretical amount of secondary com— pression subtracted from it. This is discussed further in Chapter VI. Wahls's (1962) theory provides no estimate of pore pressures. Garlanger (1972) bases his theory on a soil model described by Bjerrum (1967), and replaces the Terzaghi equation 3 (D =_§_E t av at (2.19) Q) where e is the void ratio, t the time, S the effective normal stress, and 3V the coefficient of compressibility equal to ae/aE , a constant which assumes a time-independent linear relationship between void ratio and pressure, with the equation 8? . . . . . 8e Be In this equation the compressibility,-j: , and creep rate, (5:) , are 3p c assumed to be functions of both void ratio and pressure. To obtain numerical values for these relations, the appropriate coefficients are determined from a plot of logarithm of void ratio versus logarithm of the effective normal stress. Garlanger (1972) solves equation 2.20 simultaneously with two Terzaghi equations, by a numerical process, to give the void ratio-time and the pore pressure-time relationships at every point within the consolidating soil. Although this model eliminates assumptions (1) and (2) above, it was found to be l6 inapplicable to the sludge landfill because the necessary e vs. log 3 relationships could not be realized from the undisturbed samples. The theories discussed thus far require the assumption of a value for the coefficient of consolidation, cv, and as is discussed in Chapter VI, the time-settlement relation is quite sensitive to this value. Therefore it might be concluded that although these theories more accurately model the consolidating soil, the determination of a proper value for cv may be a far more important consideration in the settlement analysis. Janbu (1965) and Davis and Raymond (1965) have included the nonlinear stress-strain relation of equation 6.2 into the consoli- dation development to replace Terzaghi's assumed linear relation. Janbu formulates the differential equation of consolidation in terms of strain, i.e. 326 8v0 t = Cv __72 _ ____ (2.21) 82 32 Q) (I) I Q) where e is the strain at a point, cv the coefficient of consolidation, v0 the nominal flow rate associated with a threshold gradient i0, and solves the equation based on different assumed final strain-depth distributions. Since his model can account for the decrease in strain with depth shown in Figure 6.3c, it allows consolidation to take place more rapidly than it would in a solution obtained on the basis of constant additional stress. Since the laboratory parameters in Terzaghi's theory underestimate the rate of settlement, such a rate increase would be desirable. However, there are problems involved in assuming a proper analytical final strain distribution for use in the l7 theory. As seen above, this theory allows for the formation of a residual pore pressure in the soil based on the concept of a threshold gradient. Davis and Raymond (1965) use the non-linear relation of equation 6.2 in a different method of formulation, based on continuity and stress conditions, and arrive at the conclusion that Terzaghi's theory accurately predicts the time-rate of settlement but overes- timates the rate Of pore pressure dissipation. This theory, along with Janbu's (1965), involves the assumption of a value of cV in its application, and thus is subject to the same explanation given previ- ously on its limitation in predicting time rate of settlement. There are also certain contradictions between the conclusions of the two theories, which makes it difficult to assess which would be the most applicable to papermill sludge. Gibson et a1. (1967) have attempted to take into account the variability of the coefficient of consolidation, and have also elimi- nated the assumption of small strains. In so doing they have formu- lated the governing differential equation for a thin clay layer subjected to large deformations. The solution is obtained for both a constant CF and a CF linearly related to the void ratio, where CF is a coefficient closely related to the familiar coefficient of consoli- dation Cv' In the solution of the former case, the linear differ- ential equation is C 32e _ 8e (2.22) __§._ __. F 3c t l8 (1+eo) where CF is the term IITEI— cv , e the void ratio, and c the distance from the midpoint of a doubly drained clay layer (at t = O). This equation holds without restriction on the form of the relation between effective stress and void ratio. It also assumes only C as constant, F with no such restriction being placed on the coefficient of permeae bility, k, and compressibility, (dO'/de), as in Terzaghi's (1943) theory. Upon solution of equation 2.22, the effective stresses can be found by application of a suitable stress strain relation (void ratio vs. effective normal stress) and the pore pressures obtained from the effective Stresses (constant total stress). The resulting pore pressures will in general not correspond to those obtained by Terzaghi's theory, however the early part of settlement will, as in the Terzaghi case, behave like tl/z. Such a result would indicate that Terzaghi's theory should adequately predict the time-settlement relation for papermill sludge even though it undergoes large deformation. Gibson (1958) has developed a theory which describes the progress of consolidation in a clay layer increasing in thickness with time. From this theory it is possible to estimate the pore pressures that develop in a clay layer or embankment that is being constructed at (a constant rate on soil which is either permeable or impermeable. Gibson initially considers the case of sedimentation taking place through still water of depth H(t) to the bottom, the current thickness of the deposit being h(t). The total vertical stress at a point a distance x from the bottom is oxx = y(h — x) + yw(H - h) = oxx + pw (2.23) 19 where p ¢is the pore water pressure, y is the total unit weight of V the deposit material, and Exx is the vertical effective stress. The continuity equation for one dimensional compression is 2 _. 8 pw 30xx v 7 8t (2.24) Combining 2.23 and 2.24, Gibson obtained the equation governing the pore water pressure in the sediment, 2 3 p 3p w= W _ dil v9.11 cva X2 at Yw dt + Y dt (2'25) where y' = y _‘Yw . In bank or landfill construction problems with saturated fill, H(t) = h(t) and equation 2.25 becomes 3 p apw dH VBXZ =n—‘Ya‘e (“6’ For a permeable base the boundary conditions are pva= 0 at )<= 0 and pyl= O at }<= H. Gibson solves equation 2.26, subject to the preceding boundary conditions, for the case of deposition occurring at a constant rate (H = mt). He presents the solution as a series of , p . m t . curves of >Huomwmmllofiumu vHo> a .ouswmmum .OH o .m.~ muswaa .H __ ________l __:__4_1 mHaEmw wowaoamu 97.50 summon; III) 0 .AHmuOHQEoo Canaan mmHaEmm wOAHSumflwcd mononumfiv H u oeumu ucoEmuocw pmoa nu l 0:221 PIOA H v owumu newsmuoafi vmoH nv CHAPTER III EVALUATION OF SLUDGE ENGINEERING CHARACTERISTICS The physical properties and stress—deformation behavior of the papermill sludge are needed for making predictions for comparison with observed field behavior of the experimental landfill. Methods used for the measurement of these engineering characteristics are described below. Reference is made to standard test procedures where possible. 3.1 Physical Properties Physical properties of papermill sludge characterize, to some extent, the quality of the sludge relative to engineering purposes. Those properties important to this project include water content, unit weight, specific gravity, ash (or organic) content, and consistency limits. 3.1.1 Water Content The water content of a soil or sludge sample is defined as the ratio of the weight of water to the weight of dry soil or dry sludge and is usually expressed as a percentage. Drying temperatures for sludges are the same as used for mineral soils (105 - 110°C). In order to obtain consistent dry sludge weights, careful control of the oven temperature is required. Care must be exercised so as to obtain a representative sample that avoids local variations. A minimum 25 26 sample size of at least 10 gm of dry solids is recommended. Lambe (1951) gives additional information on the water content of soils. Fresh papermill sludges contain large amounts of water, hence some prefer to use solids content by weight rather than water content by weight. The solids content is defined as the ratio of the weight of solids to the weight of the wet sample. A simple conversion from solids content to water content is 100 w = 100 I % dry solids - 1] (3'1) ww where w = —fi— (100) is the water content in percent based on the dry 3 weight of solids, NS, and the weight of water, WW. Water contents of sludge samples taken from the landfill are given in Table 5.2 and Figure 5.1. The lower layer had an average initial water content of 265 percent with a range from 213 to 308 percent. The upper layer had an average initial water content of 257 percent and a range from 212 to 290 percent. All water content samples were taken shortly after the sludge had been placed in its final location by the dragline. Variations present are due to: (1) changes in sludge output from the dewatering plant, (2) localized surface wetting and drying as a result of weather changes, and (3) different times of sludge exposure before sampling. It should be noted that after the construction of a sludge layer the water contents toward the bottom were less than those at the top because leachate drained from the sludge into the bottom sand blanket during construction. Appli— cation of the surcharge reduced the water content throughout both sludge layers as the leachate was expelled. The water contents 27 resulting from this are shown in Figure 5.1 and are discussed in Chapter V. 3.1.2 Unit Weight The unit weight of sludge is defined as the weight of the aggregate (sludge plus water) per unit volume. It depends on the solids content, unit weight of the solid constituents, and the degree of saturation of the sludge. The natural unit weight can be deter— mined by careful volume and weight measurements. The unit weight of fluid sludges may approach that of water (62.4 1b/cu ft) whereas the unit weight of dewatered sludges cannot exceed that for the solid constituents. The dry unit weight, Yd’ may be computed as G s Yd l + e Yw (3'2) Vv where GS is the specific gravity of the solids, e = _V—- is the void 3 ratio expressed in terms of the volume of voids, Vv’ the volume of solids, V8, and yw is the unit weight of water. Two procedures were used to determine the total unit weight of the papermill sludge as placed in the landfill. In the first procedure, a truck carrying sludge was weighed both when full and when empty to determine the total weight of the sludge being carried. The volume of the truck box was then determined and divided into the sludge weight to determine the unit weight. This procedure gave a total sludge unit weight of 69.7 lb/cu ft. The second procedure involved packing the sludge by hand into a bucket of known volume (1/10 cu ft), and then weighing to determine the quantity of sludge in 28 the bucket. The sludge was placed into the bucket in 5 lifts, and care was exercised to be sure that no air pockets were present. The total unit weight determined from this procedure was 69.0 lb/cu ft. The second procedure is similar to the method used for determination of the unit weight of fresh concrete. 3.1.3 Specific Gravity The specific gravity of papermill sludge is the ratio of the weight in air of a given volume of sludge particles to the weight in air of an equal volume of distilled water at a temperature of 40C. The lower limit for sludge will approximate the specific gravity of the organic material. The upper limit will correspond to the specific gravity of the mineral matter, generally greater than 2. Accurate determination of the specific gravity requires special care because of the presence of small gas bubbles in the sludge sample. This was overcome by the application of a vacuum to the pycnometer containing the water and sludge. Details of the test to determine the specific gravity of the sludge solids are given under ASTM designation D 854-58. Oven dry test samples were used for the papermill sludge. 3.1.4 Ash Content, Organic Content The organic material of sludge, primarily cellulose fibers, is combustible carbonaceous matter, whereas the mineral constituents are incombustible and ash forming. In the manufacture of paper, kaolinite is used in filler and coating operations. In waste paper reclamation this clay is removed from the fiber and becomes a part of the paper sludge. The sludge also contains small amounts of aluminum hydrate, titanium oxide, lime and iron (Gillespie, Gellman, and 29 Janes, 1970). The ash content of papermill sludge is determined by firing an oven dried sample in a muffle furnace at a temperature of 925 i 25°C (ASTM test method D 586—63). The ash content AC is determined from the equation a _ weight of ash or residue Ac (A) dry weight of sample x 100' (3'3) MacFarlane (1969) states that for peat it is standard engineering practice to determine the ash content as described above and then to consider the organic content equal to (100 - Ac)' Comparative results (Andersland and Laza, 1971; Andersland and Paloorthekkathil, 1972) between the ash content determined from the above method and the organic content determined by the method given in Agronomy No. 9, Sec. 92-3.3 (Black, 1965) support the use of (100 - AC) for estimating the organic content of papermill sludges. Although the kaolinite also loses its OH lattice water when fired to 925°C, this dehydration would amount to only a small portion of the total combustible material. The ash content of the sludge in the landfill will remain essentially constant with time (Gillespie, Mazzola, and Gellman, 1970). This has been attributed to the presence of lignin and clay and the absence of sufficient nitrogen in the sludge, inhibiting the biolog— ical breakdown of cellulose. 3.1.5 Consistency Limits The consistency, or Atterberg, limits indicate the range of water contents in which a soil or sludge may be considered as a fluid, 30 plastic, or solid. The liquid limit is the water content at which the _ soil or sludge has such a small shear strength that it will flow and close a groove of standard width when jarred in a specified manner. The plastic limit is the water content at which the soil or sludge begins to crumble when rolled into threads of a specified size. The amount of water which must be added to change a soil or sludge from its plastic limit to its liquid limit is an indication of the plasticity of the material. The plasticity is measured by the plasticity index, which is equal to the liquid limit minus the plastic limit. Detailed procedures for the consistency limits are given by Lambe (1951). Values for the sludge can be found in Table 5.1. Papermill sludges containing fibers do not readily lend themselves to the standard consistency tests. The fibers interfere with the test procedures and probably alter the shear strength of the material adjacent to the standard groove in the liquid limit test. Andersland and Laza (1971) show that both the liquid and plastic limits decrease with a decrease in organic content. 3.2 Stress Deformation Characteristics The stress-deformation behavior of papermill sludge will deter- mine its volume change and settlement and will control the stability of sludge landfills. The methods used for evaluating the consolidation behavior and the undrained shear strength of the sludge are given below. 3.2.1 Consolidation Behavior The process of leachate flow from sludge, involving volume change as a function of time, is called consolidation. When volume change occurs only in the vertical direction, as in a horizontal sludge 31 layer (Figure 2.1a), changes in the surface elevation are labeled settlement. Two forms of volume change in papermill sludges include primary and secondary compression (Figure 3.1). Primary compression involves a transference of load from the pore water to the sludge structure and is accompanied by a change in volume equal to the volume of water drained from the sludge. The rate at which primary compression occurs in sludge is directly related to the sludge permeability (the speed at which pore water can escape). Pore water pressure measurements taken during the settlement study provide information on this rate of consolidation. When the excess hydrostatic pressure associated with primary compression has been dissipated, the change in void ratio generally continues at a reduced rate. This phenomenon is referred to as secondary compression and is Often expressed by the slope, Ca’ of the final portion of the time-compression curve plotted on semi-log paper (Figure 3.1b). Laboratory consolidation tests (Lambe, 1951) were used to provide quantitative information on the sludge compressibility. The Wykeham Farrance consolidation test machine shown in Figure 3.2, designed by Professor A. W. Bishop, provided consistent laboratory consolidation test results. The first step required in running a test on fresh sludge (sludge as placed in the landfill) was to carefully place the sludge, in small amounts, into a 2—1/2 in. diameter by 3/4 in. high consolidation ring and to then knead the mass by hand to obtain a continuous sample free of large air pockets. The top and bottom of the sample were carefully smoothed off and trimmed to conform to the right height. The sample was then placed in the cell chamber (with 32 perspex wall) shown in Figure 3.2b and the clamp ring and top pressure pad were situated in their proper location. The cell was then placed in the consolidation machine (Figure 3.2a) and the load increment applied. Drainage from the sample took place through two bauxilite discs, one located on the bottom of the cell and one attached to the top pressure pad. Deformation of the sample was obtained from a dis- placement transducer attached to the frame of the consolidation machine and connected to a Sargent recorder. Recorder output was verified at the start of testing by comparison to deformations measured with a dial gauge. In a standard, multiple increment test, stresses of 0.1, 0.2, 0.4, 0.8, 1.6, and 3.2 kg/cm2 were applied for a period of 24 hours to the sample. Special single increment tests were also carried out, usually involving a 24 hour time period. Undisturbed block samples of sludge were obtained from the landfill when one of the confining dikes was removed for a stability study. Consolidation tests were run on sludge samples trimmed from these blocks. After a block was cut from the exposed sludge slope, it was wrapped in aluminum foil and plastic wrap and placed into a one cubic foot wooden box. Wax was then poured around the sample and the box was sealed shut. Three block samples were taken from each sludge layer at different elevations and transported back to the soil mechanics laboratory for testing. Two blocks were chosen to provide samples for laboratory consolidation tests. Block B was located at the mid-point of the upper sludge layer, 4.0 ft. below the upper sand blanket, and block F at the approximate mid-point of the lower sludge layer, 4.0 ft. below the 33 middle sand blanket. A total of four consolidation tests were run on samples obtained from each block. Two of the tests were run with rapidly applied load increments of 15 min. duration, and two with load increments of 12 hr. duration. The rapid loading tests were used to obtain a definitive e vs. log 3 curve and had load increment ratios less than one. The 12 hr. tests were run with a load increment ratio of one. Because of the fibrous nature of the sludge, standard wire saws and trimming devices could not be used to trim sludge samples from a block. A regular hand saw was first used to cut a 6" X 6" X 4" chunk of sludge from a block, and then a small (1 lb) rotary electric hobby tool with a rapidly rotating (24000 rpm) 3/4 in. diameter circular saw tooth blade was used to trim the sludge to the consolidation ring dimensions (3 in. diameter, 3/4 in. high). Once inside the ring, the sludge surface was wetted slightly and smoothed to conform to the ring height. Although this procedure resulted in considerable disturbance, both through handling and vibration from the saw, the low sensitivity of the sludge allowed fair results to be obtained. Consolidation characteristics of the undisturbed samples are summarized in Table 5.3 and Figures 5.5 and 5.6. 3.2.2 Undrained Shear Strength The undrained shearing resistance of papermill sludge may be determined using a cylindrical compression test (Bishop and Henkel, 1962) or a vane shear test (Terzaghi and Peck, 1967). The vane shear test was used to measure the increase in undrained shearing resistance, with consolidation, at various levels in the experimental sludge landfill. The vane shear apparatus consists of a four—bladed vane 34 attached to the bottom of a vertical rod, as shown in Figure 3.3. The vane and rod can be forced into the soft sludge without appreciable disturbance. The assembly can then be rotated and the shearing resis- tance computed by using the dimensions of the vane and the observed torque. The sludge fails along a cylindrical surface passing through the outer edges of the vane, as well as along the conical surfaces at the tOp and bottom of the blades. When the vane is rotated rapidly through several revolutions, the sludge becomes remolded and the shear strength in this state can be determined. The ratio of the undisturbed shear strength to the remolded value gives the sensitivity of the sludge. Details on the apparatus and procedures for the vane shear test as used on the project are given in Chapter IV. increments of stress compression compression 35 pore pressur vertical effective stress ‘P time primary compression I secondary compression a) Primary and secondary compression. primary compression 1 T secondary compression I T“‘ one decade b) Definitions. Figure 3.1. Time-compression curves. (b) Figure 3. Z. (a) Consolidation machine and recorder. (b) Fixed ring consolidation unit and sludge sample. 37 torque wrench IIITTTIIIIITT‘r socket drive head 1’.sand' :.”.H.f:::.lz ‘.3{713::f}2..19 .. //////// l ball-cone clamp //// extension rod body vane Figure 3.3. Vane shear apparatus. CHAPTER IV CONSTRUCTION, INSTRUMENTATION AND MONITORING 4.1 Construction of the Experimental Landfill Construction methods employed at the site are summarized here for later reference. They are described in terms of the site prepa- ration and dike construction, sludge placement, drainage blanket place— ment, and earth surcharge placement. The B. G. Danis Company, Inc., Dayton, Ohio, provided equipment and operators. Coordination of construction operations was handled by the author through Mr. Tom Danis, Sr. Field work on the papermill sludge landfill commenced on August 23, 1971. 4.1.1 Site Preparation and Dike Construction A section of an old gravel pit located close to West Carrolton, Ohio, and within hauling distance of the papermill was selected for the experimental sludge landfill site. A pre-construction map of the immediate gravel pit area and the dike layout is shown in Figure 4.1. Other areas of this gravel pit already contained large amounts of dewatered papermill sludge from previous fill operations. A small pond in the gravel pit, about 400 ft. north of the existing slope, provided a reference as to the groundwater elevation. This information indicated that the groundwater level would not be encountered during dike construction. The pond also served as an outlet for the drainage pipe installed in the lower sand blanket. Several bench marks were 38 39 established and a stadia survey was completed of the immediate gravel pit area, as shown in Figure 4.1. From the stadia survey it was apparent that a maximum dike grade elevation of 95.5 ft. would allow the entire west dike and part of the south dike to be shaped from the natural ground. Excavated soil would provide material for the remaining dike areas. The bottom grade elevation of 77.0 ft. was about 7 ft. above the groundwater level. Prior to excavation for the dikes, an 8 in. diameter pipe was installed to the pond to provide drainage for the sand drainage blankets. The Upper end extended under the north dike and into a gravel pocket in the lower sand blanket (invert elevation 77.0 ft) as shown in Figures 4.2 and 4.3. The lower end (invert elevation 73.6 ft) drained into the pond. The gravel drain surrounding the pipe entrance was continued up the inner dike wall to provide drainage for the middle sand blanket (Figure 4.3). Observations at the pipe outlet both during and after construction indicated that it was functioning properly. The pipe joints were not sealed, hence some seepage to and from adjacent soil could occur. The top inside corners of the dikes and the required grades were established using results from the stadia survey (Figure 4.1). A one cubic yard 35-ton Link Belt power shovel did the bulk of the excavation work, while a D-6 caterpillar dozer moved the excavated earth and shaped the dikes. Excavation began near corner 1 (Figure 4.1), with the power shovel digging into the existing bank and side casting to the dike area. The dozer would spread the soil toward corner 2, gradually building up the south dike. As grade was 4O approached, the dozer spread the soil toward corner 3, building up the east dike. The excavated material was a well graded till consisting of particles ranging in size from clay to gravel. It was easy to handle and during placement some compaction was achieved from the dozer, thus permitting construction of a fairly steep inner dike slope. This slope helped minimize the volume of material required and reduced construction time. After the power shovel had completed the excavation near the top, it was moved to the bottom area and proceeded to excavate down about 6 ft. to the final grade at elevation 77.0 ft. The excavated material was used to complete the north and east dikes. Corner 3 was left low until sand for the lower drainage blanket had been dumped inside the dike area. When the bottom of the landfill area reached grade, the power shovel was converted into a dragline unit, and soil for completing the dikes was obtained outside the fill area. The dozer spread this soil, and also leveled the sand dumped for the lower drainage blanket. The gravel surrounding the upper end of the drainage pipe and extending up the slope (Figure 4.3) was placed near the end of the dike construction period. Shaping of this 10 ft. wide gravel chimney drain was handled by the dozer. 4.1.2 Sludge Placement After the spreading of the sand for the lower sand blanket and the shaping of the gravel chimney drain, sludge was dumped by truck over the west and south dikes as shown in Figure 4.4b. The sludge exhibited a plastic behavior and would not support the usual construction equipment. The dragline (Figure 4.4a) proved ideal for 41 moving the sludge to other locations in the landfill. A lightweight dozer with extra track width arrived at the site too late for use in spreading the sludge. Current use of this lightweight dozer by the contractor indicates that it is quite effective in moving sludge and that it should be considered for future operations. Some initial difficulty was encountered when unmonitored sludge dumping was permitted over a weekend. Unusually high sludge production (about 300 cu yd/day) caused more area to be used at the bottom of the landfill than was anticipated, and a sludge flow towards the center of the site occurred. Two settlement plates with vertical rods were shoved out of position and required replacement. Leachate draining from about ten feet of sludge stacked along the west dike saturated the sand blanket. Temporary channels were dug in the sand blanket to the drainage pipe to remove the leachate. ‘After the re-leveling of the sand surface and a more uniform re-placement of the sludge with the dragline, dumping was continued with daily monitoring. Shortly thereafter, sludge production dropped to about one-half its normal rate, delaying the landfill construction. The dragline was used for the placement of both sludge layers. 4.1.3 Drainage Blanket Placement Placement of the lower sand blanket was described in the preceding sections. When the lower sludge layer reached grade it was roughly leveled with the dragline bucket, and then two telephone poles cabled together were dragged over the surface. This reduced variations in the sludge surface to about i 3 inches. Sand was then dumped along one dike edge and distributed by dragline over the sludge layer. Again 42 the two telephone poles were dragged over the surface to give a reasonably level sand blanket. The use of a lightweight dozer for the spreading of the sand was not attempted because of the possibility of its sinking into the sludge and because the surface of the lower sludge layer was 11 ft. below the top of the dike, as shown in Figure 4.5. The steep inner dike slopes at this time would have made an attempt to use a dozer quite dangerous. Sludge placement was resumed upon completion of the middle sand blanket. When the upper sludge layer reached grade, the surface was roughly leveled off with the dragline bucket and then brought to final elevation by dragging the pole rig over the surface. Sand was dumped at the dike edge and a lightweight dozer pushed the sand out over the sludge surface. Because the sand acted as a supporting mat, the small dozer was readily able to travel over the landfill while spreading the sand. Placement of the sand with the dozer was considerably faster than with the dragline. 4.1.4 Earth Surcharge Placement The earth surcharge was constructed of the same soil used to build the dikes. It was obtained outside the dike area by the dragline and dumped onto the landfill surface near instrument group 7. Both the D—6 and lightweight dozers were then used to spread the soil over the required area. Some compaction occurred as the dozers operated over the surcharge. Placement required only 1-1/2 days, hence for analysis purposes the surcharge was placed instantaneously. The lateral dimensions of the surcharge were selected (Figures 4.2 and 4.3) so that one-dimensional consolidation would be approximated at all instrument 43 group locations. Field density determinations using the sand—cone method establisned a soil unit weight equal to 130.4 pcf for the surcharge material. Preliminary consolidation data indicated that the 3 ft. thick soil layer would give time-settlement curves suitable for the project research objectives. 4.2 Instrumentation and Monitoring The instrumentation and monitoring of the experimental sludge landfill provided information, both during and after construction, on vertical movements, pore water pressures, lateral earth pressures, temperatures, and undrained shear strengths. Instrument placement and monitoring commenced on September 10, 1971, with the installation of settlement plates in the lower sand blanket. Instrumentation of the landfill continued as construction progressed. Monitoring began with each instrument installation and was continued throughout the year. The frequency of readings was based on the relative change in the observed phenomena, with the most frequent readings (2 per week) required during the first few weeks after construction. The following sections describe the settlement plates, piezometers, total pressure cells, temperature sensors, and vane shear tests used to obtain the field data. 4.2.1 Settlement Plates A settlement plate consisted of a 2 ft. by 2 ft. by 1/8 in. thick aluminum plate with a 3/8 in. diameter steel rod of known length attached to the center, as shown in Figure 4.63. Additional rods of known length were added at each location as sludge placement progressed. 44 To minimize the adhesion of the sludge on the steel rod, a l-l/2 in. O. D. aluminum tube was placed around each rod when it was installed. Radiator hose (1-1/2 in. I. D.) provided a flexible connection for the aluminum tubing. Elevations taken with a surveyor's level (or transit) on the tOp of each steel rod were referenced to a bench mark outside the fill area. Installation of the plates in a sand blanket and in the sludge is shown in Figure 4.6. A hole 3 ft. square by 4 to 6 in. deep was first excavated in the sand or sludge, the bottom was tamped lightly to densify the material, and using the plate as a guide, the bottom of the hole was carefully leveled. Then the settlement plate, attached rod, and aluminum tube were installed in the hole, an initial elevation reading taken on the plate, and the hole backfilled. Because the aluminum plates were light, there was no danger of their sinking into the sludge. The sludge consistency was such that a man could walk on its surface. A total of 32 settlement plates were installed at various levels in 8 instrument groups. The distribution of settlement plates in each group is shown in Figure 4.7. The lower plate was placed at the center of the group, with each higher plate offset 1-1/2 ft. from the center so that no interference could occur between rods and higher plates. Duplicate locations served as insurance in the event that certain groups should be accidentally destroyed during construction, and the additional data served as a check on adjacent groups. Location of each instrument group is shown in Figure 4.2. 45 4.2.2 Piezometers Piezometers measure the static pressure or head (elevation to which water will rise in an Open standpipe) of the fluid in the pore space between the solid sludge particles. The pneumatic type piezometer (Slope Indicator Company model 51401) used on this project did not require in-place calibration and was not subject to changes in sensi- tivity. The sensitivity of the transducer approaches 0.5 in. of water. Because the sludge has a high degree of saturation, the standard Norton Casagrande type filter with large pore size and low air entry pressure was used. The transducer (Figure 4.8a) converts the in situ water pressure into a pneumatic pressure that is relayed to the surface reading station by means of twin nylon tubing. Pore pressure readings were taken with the model 51421 (SlOpe Indicator Company) portable pore pressure indicator. Installation of the pore pressure transducers first required excavation of a small hole in the sludge, as shown in Figure 4.8b. At least 3 inches of sand and water were then placed in the hole, followed by the transducer, and ample slack was allowed for in the twin nylon tubing. Next, the piezometer was covered with a minimum of 3 inches more of saturated sand followed by a layer of wet sludge. The sand pocket was used because it was unknown how sludge decomposition might influence piezometer readings. The twin nylon tubes were connected to a terminal unit housed in a waterproofed wooden box located at the edge of the landfill. The pore pressure measuring system appeared to function well, with no pinched or disconnected lines occurring during construction operations. The observed pore water pressure—time curves 46 indicate that the readings are consistent and that they are in agreement with duplicate piezometers. A total of 16 piezometers were installed as part of instrument groups 5, 6, and 7. Their group identification and relative elevation is shown in Figure 4.7, with group locations given in Figure 4.2. Piezometers located at the same level as a settlement plate were offset about 6 to 12 inches from the plate. 4.2.3 Total Pressure Cells Total pressure cells assist in determining the state of stress in the sludge mass. The model T-9010 (Terra Tec) cell consists of two 9 in. diameter steel plates welded together at the circumference with a void between them that is filled with an incompressible oil. The oil transmits the external pressure to a sensing unit consisting of a double bellow assembly. Air pressure from the control unit (Terra Tec model C 1000) is applied through a closed loop system to the inside of the bellows to balance the external cell pressure. This air pressure is relayed from the surface reading station to the total pressure cell by means of twin nylon tubing. Calibration charts based on a hydraulic and a sand loading give the limits of possible pressures that can act on the cell by the sludge. Three total pressure cells were installed in the lower sludge layer near group 7, as shown in Figure 4.7. Two of the cells were installed in the vertical position to measure horizontal stresses, and the remaining unit was installed in the horizontal position to measure total vertical stresses. The horizontal cell was installed by digging a hole 1 ft. square by 4 in. deep and placing the cell so that it was 47 firmly imbedded in the bottom. An elevation reading was then taken on the cell surface and the hole backfilled. The vertical cells were pushed part way into the bottom of a similar hole, and then loose sludge was placed around the cell and tamped until the cell became firmly imbedded. An elevation reading was taken on the top edge of the cell before backfilling was completed. 4.2.4 Temperature Sensors The temperature sensors are small YSI precision thermistors which are made of a material whose electrical resistance varies sharply in a known manner with temperature. Given the resistance reading, the thermistor temperature is obtained from a calibration chart. Ten YSI precision thermistors (part #44033) were mounted at 2 ft. intervals on a 1 in. square wooden pole. The thermistors and wooden pole were installed via a 4 in. I. D. hollow core auger using a truck mounted drill rig. Since the augered hole was not expected to remain open without casing, the wooden pole was lowered through the hollow core of the auger, and then the auger was carefully pulled up around it. The elevation of the top thermistor equals 95.43 ft., with the additional thermistors being located below this at 2 ft. intervals. Thermistor lead wires followed the pole to the surface and then across the fill to the readout box. Resistance readings were obtained with a model 300 digital passive scalor from Western Electronics, Inc. Data indicated that 9 of the 10 thermistors were functioning properly. 4.2.5 Vane Shear Tests All but one set of vane shear tests were carried out using a Geonor H-70 heavy field inspection vane borer. It is a hand operated 48 unit that comes equipped with a torque wrench, 3 different size vanes, extension rods, and various accessories. The basic unit, as it would be set up in the field, is illustrated in Figure 3.3. Undrained shear strengths up to 12 tons/sq m can be measured with the small vane (55.9 x 111.8 mm). One final set of vane strengths was taken using a 2 in. 0. D. Acker vane that was pushed into the bottom of a hole augered to within 6 in. of the test depth. This prevented the capacity of the torque wrench from being exceeded. The test procedure for all but the last set first involved driving, with a sledge, the vane and claw coupling (lower part) into the sludge to the desired depth. The measurement of shear strength was then carried out in four stages for each depth. The extension-rod friction was first measured by turning the torque wrench slowly clockwise through an are a little less than 180 degrees. The rods were then rotated still further in a clockwise direction until the dog- coupling in the lower vane borer engaged. The measurement of shear strength was then taken by slowly turning the extension rods clockwise until the maximum shear reading was obtained. The difference between the maximum reading and the rod friction reading, with the proper conversion, equaled the undrained shear strength of the sludge. The vane was then turned 20 times clockwise in order to remold the sludge adjacent to the vane and rod. The rod was then rotated 1/2 of a revolution counterclockwise before measuring the rod friction and shear strength of the remolded sludge using the same procedure as before. Shear strengths were obtained at 3 elevations in the upper sludge layer and at two elevations in the lower sludge layer for all but the final set. Because of augering through the surcharge and upper 49 sand blanket with a hand auger, the upper layer rod friction was low and difficult to read on the torque wrench. Shear strengths were relatively easy to obtain. In the lower sludge layer much greater driving resistance was encountered and rod friction became high. Thus the vane shear strengths were obtained only at the two higher elevations in the lower sludge layer. At the lower elevation the capacity of the torque wrench would have been exceeded using the small vane. The final set of vane shear strengths, taken using a truck mounted drill rig to pre-auger to the desired depth, had the strengths recorded at one foot intervals throughout both layers. 50 +82 0 +8Z.3 +8l.9 3 . North gravel pit area / w line of inside crest of dike +- 83.4 / / \ +82.6 + 81.9 +891 / 96. 7 82. 9 + 83. 9 82.4 2 c . . \ ex1st1ng slope *3, + + 9577 + 95.8 84.2 95.2 99 2 97_9 -1-9 '5 +94.2 V + 98.5 96.2 \ 97.3 +97.7 + +97.8 Legend: 1 + Elevations 99.8 1 __ _ _ Dike layout top inside corners 0f dike (Cl-"'4’ 99. 5) / I Corners of dike ‘V gravel pit area V Grass Scale: 1" = 30' Assumed elevation datum top of gas line marker = 100.00 ft. Figure 4.1. Pre-construction map of existing gravel pit area including dike layout. 51 l l drain pipe 1 North slope dovni ~ "7” / ——*"‘Zfl,JLflflfljL——J%— dike t 14' 99.3 . gravelpocket in san limit of surcharge \ I / r —l—\ _. _ _ .. ._ _ __.! .. _ ‘ \ exisiting 4” "J \\ gravel I I -" \ pi wall ' 4 ' + \ l ' ‘ _— ‘__’1 ' 23 16 16' I I dike limit of 5 l bottoln l : ‘ + 23' + sand~blanket ' .+ 78 ’ _— : 3 + + 7 I | + Z I .— I lxneH.source I ‘ I \ / ‘ \\‘_; _ __ _ fl / slope domn1 100.5 E>\\\j dlke 20' K7 / l l I slope down ' Legend: + Instrument group I Elevations ----- Earth surcharge limit Scale: 1"=30' ——-——-—— Bottom sand blanket limit Figure 4.2. Experimental landfill and instrument group locations, plan view. .coflosuumcoo mo fine no ovmw chaos .Smoatfiv SEEMS Ho sofiuom .m .v madman .3 n :H Snow 59:... H0330 E muexams ommfimyw vnmw m .H 3080 seam + m mama unmEeSuom _ uwcewod 3.8 «3... £85 33 52s a __w + +11 28333 a 28f _m .o 335:: Eco $3 + \ _ .3:me empdfim .832 ciao: .3th He>mhm 033 _oH air. + 20:: 2 53:3 . ._ . . . QVZU fiuhmw + II swig owed? swans + _o .5 ._::__ __:::\E Till v macaw «selfish—m5 owumgonsm stem m maouw unmasuumcfl 53 .unogoomfim wmwsfim .mogm sump o5 uo>o wGRESQ 3V .4 .4 «Human .Gomumnomo 053an Adv . u <1.) I tIlKl.-\()))I»v.x . . , A : r 2 54 . Hoax owwgm .333 23 mo «Gogooflm 9.3.26 :36an amps: Hansonhnemunm . 0*! .9 ~ .m .v 3&5 55 I 3/8 in. dia. steel rod 1-1/2 in. O. D. aluminum tube Aluminum plate 2 ft. x 2 ft. x 1/8 in. (b) Placement in the sludge, carpenters level shown on the plate. Figure 4.6. Settlement plate. 56 .mdsouw acmesnumcH use aw mHHmo mhsmmmua HouOu ecu .wumumeonwwm .mmumHa unmEmHuumm mo cowusnwuuwwn .x.s .rsmum AHmuco~Huoc u o .Hmuwunm> I ov mHHwo musmmmuu HmuOH O mnwquonmwm IT H mmumaa unmEmHuumm mucumHEumzu “NV _ K \ \r \ \ \ \_ K R \ \. \ \ \ \ \t \ u\ \ HHOm HNHDUWC \ \k \ \._ ,. ) . . 1 ~ .2. . . If: r \I . 1.1;.» . .u. . \l p) I. )L .. . y) 1., , W Ain‘t». (f.m.u,,n....,../.,...q.. L. J... 2...: £39.. .TJI. ..,....n.,....,..u.....)..,../.v.,hu..JI .n......7.»mfl;avh 1T fleakletrfifi JI. x-.. :Qufib H Hermann PH ~.+ mwpsfim Ar Links... 3...». a... 4.54%... .._. _ JI fix”... ”4.9.1.. + IHI .._.._.,,3,;..,._....,,..).w;.,.,r...... JI 1.4%,, 43.9,... e. . H H _ .fl .wH H . _N ® m 5+:I 4).). ) s 4193?.......;..?....».. _ I__.l ..,,........H.,Marijuana H- ..n,Guam.....,..m...r..,.,.....\.\.. _Jlkwfl.........,a.fiw,, .. ,.. . — :OI _ m m _ Ea _ fill; _ mq.w0H .Hm _ fl wwumLQHSm Hwy # ms m n 0 \\\\\¥ m awom qua Alllll nausea: macaw nameapum:w 57 A 11.75" 1 PVC Sleeve Gasket iaphragm Porous Electrical Filter Insulating Stone Resin .,, - ~. . . . \\\\\\i &§\\\\\ / - 4— \\\\\“ .\\ “wt ‘- -( \\\\\\.\\\\\-\\\\ |\‘\_‘\ l, -l— \\\\ \\\\\\\ _\J ~ \\\\\\\\\\\\\\\\\\\\m 1/8" Ball / Z 5 Nylon Stainless Tubing 32:5: Steel gplyethylcnc PVC Body “14 Jacket (a) Pore pressure transducer. (b) Installation in a small sand pocket in the sludge. Figure 4. 8. Piezometer. CHAPTER V EXPERIMENTAL RESULTS The experimental results are presented under three headings: physical properties of the papermill sludge, stress-deformation behavior of the sludge, and field monitoring. Each section may include both laboratory test data and field observations. 5.1 Physical Properties of the Papermill Sludge Physical properties of the papermill sludge used in the experi— mental landfill are summarized in Table 5.1. Properties given include the liquid and plastic limits, ash content, solids content, and specific gravity. Of the eight samples listed, data shown for samples L-l and L-2 each represent the average of three different locations at the given elevation. Data shown for samples U-l through U-S represent the average of three tests on each sludge sample obtained from one given location. The sludge variability within the landfill is apparent for samples U-l through U-5, although the average ash content (41.8 percent) is close to that for samples 2 and 3. The initial solids contents shown in Table 5.1 range from 26.9 to 34.4 percent by weight. Using equation 3.1, the equivalent water contents range from 190.7 to 271.7 percent. Additional water content samples taken at several instrument group locations and elevations are summarized in Table 5.2. These water contents appear to fall in the vicinity of the liquid limit. The bulk 58 59 unit weight of the papermill sludge was 69.7 lb/cu ft based on the weight and volume of a truck box full of sludge. Using a standard 1/10 cu ft bucket and careful hand placement, the observed bulk unit weight was 69.0 lb/cu ft. For the soil surcharge material, the sand cone method gave a bulk unit weight of 130.4 lb/cu ft. Water contents of the sludge in the landfill after completion of consolidation are shown in Figure 5.1. These values were obtained from the undisturbed block samples and from grab samples taken from the exposed slope face. Despite the somewhat wide range of water contents obtained, the average for the upper layer dropped to 189 percent and the lower layer to 164 percent. Ash contents from samples obtained from the undisturbed sample blocks in each layer were fairly close to the average ash contents reported in Table 5.1. Block sample B for the upper layer had an average ash content, based on three tests, of 38.6 percent. Sample F for the lower layer had an average of 39.3 percent. This indicates that these block samples can be considered as representative for each sludge layer for consolidation testing. 5.2 Stress-Deformation Behavior of the Sludgg Laboratory consolidation tests were run on fresh sludge samples and undisturbed samples taken from the landfill at the end of consoli- dation to determine parameters needed for estimating and analyzing the settlement of the landfill. In-place vane shear tests provided data on the undrained shear strength of the sludge at various stages of consoli- dation. 5.2.1 Laboratory Consolidation Results from one-dimensional consolidation tests on fresh 6O sludge samples from four different locations are summarized in Table 5.3 in terms of the coefficient of consolidation Cv’ primary compression ratio r, coefficient of secondary compression Ca’ and the compression index CC. Based on the average placement water contents (Table 5.2), sludge samples U—3 and L-2 (Table 5.1) appear to be reasonably repre— sentative of the sludge in the landfill. Data for several single increment tests, such as those recommended by MacFarlane (1969) for peat, are included. The earlier tests, including U-4-l, U-3—l through U—3-9, and L-2-l were run using the fixed ring container and the loading methods illustrated in Figures IX-5a and IX-4 in SOIL TESTING FOR ENGINEERS by T. w. Lambe (1951). All remaining tests were run on the BishOp consolidation machine. The latter tests were less subject to equipment errors and inconsistencies. Data from test U—3-10 are used in Figure 5.2 to show the consolidation characteristics of fresh sludge and include the void ratio, coefficient of consolidation, and primary compression ratio plotted against the logarithm of total effective stress. The high compression index, Cc’ equal to 1.70 represents a highly compressible material. Coefficient of consoli- dation values from both the logarithm of time and square root of time fitting methods are included for comparison. The primary compression ratio shows a sharp drop after the first load increment followed by an increase with subsequent load increments. This initial drop in r for loads of 0.1 to 0.2 kg/cm2 appears to be characteristic of the fresh sludge. Two typical compression dial reading-logarithm of time curves are shown in Figure 5.3. The coefficient of secondary compression, Ca’ shown in Figure 5.4a, increases slightly over the 61 total effective pressure range of 0.1 to 3.2 kg/cmz. Since stress appears to be a factor in determining the magnitude of secondary compression (MacFarlane 1969; Leonards and Girault, 1961), the ratio of Co to the load increment, Ap, is presented in Figure 5.4b. The ratio Ca/Ap decreases rapidly with an increase in the load increment. Figures 5.5 and 5.6 show typical consolidation test results for the undisturbed sludge samples taken from the landfill, and Table 5.4 summarizes the consolidation characteristics for each undisturbed sample test. In Figure 5.5, two e vs. log 3 curves are shown for each undisturbed block sample location along with a representative curve for a sample of fresh sludge. The curves obtained from the rapid increment tests are at higher equilibrium void ratios than those obtained from the slow tests because of the absence of secondary com- pression. The data indicate that the sample obtained from the lower layer has a lower compression index, lower initial void ratio, and a higher back-computed overburden pressure than the sample for the upper layer. The coefficient of consolidation, primary compression ratio, and coefficient of secondary compression have been plotted against the logarithm of effective pressure in Figure 5.6. The coefficients of consolidation were obtained by the square root of time method and vary widely with pressure for both samples. Substantially higher values occur at pressures below the effective overburden stress. The primary compression ratio and coefficient of secondary compression both increase with an increase in the load increment and effective pressure. 5.2.2 In-Place Vane Shear Tests Test procedures for measurement of the in-place vane shear 62 strength of the sludge were given in Chapter IV. Vane shear strengths taken after completion of each sludge layer and after partial and total primary consolidation are summarized in Figures 5.7a and 5.7b. Some consolidation occurred during placement of each sludge layer, hence an increase in strength with depth was observed before placement of the second sludge layer and before placement of the surcharge load. The degree of sensitivity, defined as the ratio of the undisturbed to the remolded shear strength is small, ranging from about 1.5 to 2.5. This is very similar to that of many clays (Terzaghi and Peck, 1967). Both layers increased substantially in strength during consolidation, as shown by data taken on March 20, 1972 (Figure 5.7a) and on Sept. 7, 1972, immediately prior to slope excavation (Figure 5.7b). 5.3 Field Monitoring Field monitoring involved making observations of elevations from the settlement plates, pore water pressures from the piezometers, temperatures from the thermistors, and both horizontal and vertical pressures from the total pressure cells. Figures and graphs are used to summarize the tabulated data, which are given in Appendices A through D. The results are presented under the headings of settlement, pore water pressures, temperatures, and lateral sludge pressures. 5.3.1 Settlement Time-settlement curves for each instrument group are shown in Figures 5.8a through 5.8h for both the upper and lower sludge layers. The upper part of the figure shows the landfill surface elevation, both during construction and during consolidation, as a function of time. 63 Also shown at different times are the vertical locations of the settlement plates and the relative thickness of each portion of the sludge landfill. Notation on Figure 5.8, such as @ - ® , indicates that the settlement of plate<::> has been subtracted from the total settlement of plate <::), in this case giving the time-settlement curve for the upper sludge layer. Upon completion of the upper sludge layer, the rapid placement of the top sand drainage blanket (2-1/2 days) and surcharge load (1-1/2 days) gave an approximation to instantaneous loading. The settlement versus square root of time curves for the top sludge layer are presented in Figures 5.93 and 5.9b for each instrument group. The initial point is not at zero since some compression of the layer occurred during placement of the sand blanket and surcharge load. The data plotted represent obervations taken after completion of the surcharge placement and give square root of time plots similar to those observed in the conventional consolidation test. Values for the coefficient of consoli- dation, Cv’ backfigured from these plots, are fairly large and vary some for the different instrument group locations. Settlement-logarithm curves for the upper and lower sludge layers are shown in Figures 5.10 and 5.11 for each instrument group. 5.3.2 Pore Water Pressures Piezometers used for the measurement of pore water pressures gave the data summarized in Figures 5.12a through 5.12g. Pore pressures are plotted against time in the lower half of Figure 5.12, with the location of the piezometer in the landfill given in the upper half. Observed pore pressures in both layers showed a consistent increase with 64 time during placement of the sludge. An abrupt increase in pore pressure occurs during the rapid placement of the surcharge load and is followed by dissipation to some residual value, perhaps related to a threshold hydraulic gradient required for flow. In the upper sludge layer the observed pore pressure increase at the center of the layer is close in magnitude to the applied pressure resulting from the placement of the top sand blanket and earth surcharge load. During the later stages of consolidation some fluctuations occurred with time for piezometers in the upper sludge layer and middle sand blanket. High rainfall, involving seepage into the drainage blankets, appears to be responsible for this pore pressure fluctuation. The pore pressure in the middle sand blanket (Figure 5.12g) is the result of a dish effect produced by the greater consolidation of the central area of the sludge landfill. Field data are given in Appendix B. 5.3.3 Temperature Thermistors used for temperature measurement gave the data summarized in Figure 5.13. An increase in temperature caused by biological activity is observed, with the higher values occurring in the lower sludge layer about 50 days after completion of the landfill. Subsequent temperatures show a pattern indicating that the sludge was responding to atmospheric and ground temperatures. Inconsistent temper- atures for thermistor 2 indicate a malfunction or damaged unit. Field data are given in Appendix D. 5.3.4 Lateral Sludge Pressures Total pressure cells installed in the lower sludge layer gave the data summarized in Figure 5.14 for both total lateral and vertical 65 pressures. Pore water pressure data from an adjacent piezometer are included on Figure 5.14 to permit the computation of effective lateral and vertical pressures. The measured total pressures increased gradually during placement of the upper sludge layer and increased sharply upon placement of the earth surcharge load. Subsequently it required about 2 months for the lateral pressures to stabilize at a lower value. The total observed vertical pressure shows an unexplained increase occurring after the initial increase from application of the surcharge. This is opposite to what would be expected as leachate drained from the sludge landfill. Data for pressure cell G7-2 have been omitted from Figure 5.14 because instrument readings indicated that there was a malfunction. Field data are given in Appendix C. 66 TABLE 5. 1 PHYSICAL PROPERTIES OF THE PAPERIWILL SIJFDCJI” (‘ , " ' ' I .’ 32.11198" sample Consmtency 11m1ts Ashz Solids3 Specific 1 No. Elevation L P content content gravity in layer, fl. W W % ‘70 by “ft. L—O 8 5 325.4 141.6 35.7 28.5 2.01 L-l* 2.5 257.3 102.7 42.2 27.2 2.05 L-2* 7 247. 7 105.6 43.3 28.2 2.07 U-1+ 2.5 184. 5 86.0 59.4 34.4 2.24 U-Z+ 4 218.5 101.6 46.5 31.9 2.07 [1-3+ 5 297. 5 133.0 36. 5 26. 9 1. 91 0-4+ 7.5 287. 4 122.1 34. 2 29. 0 1.87 U-5+ 10 302. 8 138.6 32. 2 28. 4 1. 92 *Average of three samples. +Average of 3 tests per sample location. 1 L --liquid limit. P --p1astic limit. ASTM test methods D 423-66 and W W D 424—59. ZASTM test method D 586-63. 3Solids content of fresh sludge. Water content by dry weight given by the equation 100 ”/0 solids by wt. W070 : 100 I: l J. 4ASTM test method D 854-48. Laboratory test sample locations. Upper sludge layer :8 [1-4 x U-3 x U-2 \ X U’l ' . . {\\ \fi\ \\ x L-Z Lower sludge layer L-O \\\\\ x Sand ¥- mmwfi X Natural soil 67 TABLE 5.2 SLUDGE PLACEMENT WATER CONTENTS L __.—__. __.—__— Elevation Group No. in layer '- (ft) 1 2 3 4 5 6 7 8 Lower Sludge Layer 2'5 ' - - - 242 292 - - 277 3.0 - 282 - 284 230 ' 283 ' 245 4.0 - - 308 270 ' ‘ 276 298 5.0 - - ' - 261 269 262 213 283 240 265 244 264 271 262 219 226 253 7-5 ‘ - - 279 267 : - - 267 266 252 265 253 257 8.0 - - 274 274 273 - 271 - 291 264 246 258 256 9.0 - - 278 275 - - .. - 294 10.0 - - - - 280 - _ _ 267 276 255 Upper Sludge Layer 2.5 262 ‘ ' ' 268 ' 270 ' 260 ' 248 270 262 270 262 290 3.0 ‘ ‘ " - 251 - . _. 262 6.0 ' ‘ ' ‘ 251 279 244 ' 284 264 262 264 278 271 276 277 261 7.5 - ' ' ' 235 254 232 ' 256 237 234 257 234 224 232 269 212 Oven temperature 105°C. Average initial water and solids contents: Lower sludge layer 265.%, 27.4% Upper sludge layer 257.%, 28.0% 68 00000.0 00.0 0000.0 :00. 0 0.0 - 0.0 00000.0 00.0 0000.0 0000 0 0.0 - 0.0 00000.0 00.0 0000.0 0000. 0 0.0 - 0.0 00000.0 00.0 0000.0 0000.0 0.0 - 0.0 00.0 00.0 00000.0 00.0 00000.0 0000.0 0.0 - 0 40 0-0 00.0 .00-00 .000500600 0 0000.0 -- 0000.0 0000.0 000 0 - 0 40 0-0 00.0 .00-00 .000500600 0 00000.0 -- 0000.0 0000.0 000.0 - 0 40 0-0 00.0 .00-00 .000500600 0 00000.0 -- 0000.0 0000.0 000 0 - 0 40 0-0 00000.0 00.0 0000.0 0000.0 0.0 - 0.0 00000.0 00.0 0000.0 0000.0 0.0 - 0.0 00000.0 00.0 0000.0 0000.0 0.0 - 0.0 -- 00.0 0000.0 0000.0 0.0 - 0.0 00000.0 00.0 0000.0 0000.0 0.0 - 0.0 00.0 00.0 00000.0 00.0 0000.0 0000.0 0.0 - 0 40 0-0 00000.0 00.0 0000.0 0000.0 0.0 - 0.0 -- -- 0.0 - 0.0 00000.0 00.0 0000.0 0000.0 0.0 - 0.0 00000.0 00.0 0000.0 0000.0 0.0 - 0.0 00000.0 00.0 0000.0 0000.0 0.0 - 0.0 00.0 00.0 00000.0 00.0 0000.0 0000.0 0.0 - 0 40 0-0 0000.0 00.0 00000.0 00000.0 00 - 0 0000.0 00.0 00000.0 00000.0 0 - 0 0000.0 00.0 0000.0 00000.0 0 - 0 0000.0 00.0 0000.0 0000.0 0 - 0 0000.0 00.0 000.0 000.0 0 - 0 0000.0 00.0 000.0 000.0 0 - 0 00.0. 00.0 00000.0 00.0 000.0 000.0 0 - 0 x0 0.: 0x00090000 0010/. u w00 010.70o\1m.v.c .02 .02 .Ho 1 4 - . 0 me o 980 o o 0 . 0.. 0000000006000 0 .H 0 m m U U H A. 40038.0 MQC 0.0qu vwmudflm 000000 00000 .000000000000000 2000000000200 00 0002000 0.0 00000 69 0000.0 00.0 00000.0 00000.0 0.0 0.0 0000.0 00.0 00000.0 00000.0 0.0 0.0 0000.0 00.0 0000.0 00000.0 0.0 0.0 0000.0 00.0 0000.0 00000.0 0.0 0.0 0000.0 00.0 0000.0 0000.0 0.0 0.0 00.0 0000.0 00.0 0000.0 0000.0 0.0 0 +00 0.: 00.0 .03-0 .000500600 0 0000.0 00.0 0000.0 0000.0 0.0 0 +00 0-0 0000.0 00.0 00000.0 00000.0 0.0 040 0000.0 00.0 00000.0 00000.0 0.0 0.0 0000.0 00.0 00000.0 00000.0 0.0 0.0 0000.0 00.0 0000.0 0000.0 0.0 0.0 0000.0 00.0 0000.0 0000.0 0.0 0.0 00.0 0000.0 00.0 0000.0 0000.0 0.0 0 +00 0.: 00000.0 00.0 0000.0 0000.0 0.0 0.0 00000.0 00.0 0000.0 0000.0 0.0 0.0 00000.0 00.0 0000.0 0000.0 0.0 0.0 00000.0 00.0 0000.0 0000.0 0.0 0.0 00000.0 00.0 0000.0 0000.0 0.0 0.0 00.0 0000.0 00.0 00000.0 00000.0 0.0 - 0 40 0-0 00000.0 00.0 00000.0 00000.0 0.0 040 00000.0 00.0 0000.0 0000.0 0.0 - 0.0 00000.0 00.0 0000.0 0000.0 0.0- 0.0 0000.0 00.0 00000.0 00000.0 0.0 - 0.0 0000.0 00.0 00000.0 00000.0 0.0 0.0 00.0 0000.0 00.0 00000.0 00000.0 0.0 0 40 0-0 00000.0 00.0 0000.0 0000.0 0.0 040 00000.0 00.0 0000.0 0000.0 0.0 0.0 -- -- -- -- 0.0 0.0 00000.0 00.0 000.0 0000.0 0.0 0.0 00000.0 00.0 0000.0 0000.0 0.0 0.0 00.0 00000.0 00.0 -- 0000.0 0.0 0 0 0-0 70 6:2 26> 0000000 - .0300 0000.0 0 0.090000 0 000080.000 O Q .N .m snowfm 0000000000000 0003030000000 09$ 0000-00000: U $800000 0000000000500 1 U - .H .0800 -0 .0 50000000000000 000000000000 00 0000000800000 1 U > 503030qu00 .00 “000008-0006 1 o .0000; 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Nance. oo.H I om.o ammoo. N.mn. mmmo. oqao. ow.o I oq.o «nooo. w.oo mmmo. ammo. oq.o I o~.o mmqoo. m.om «one. come. om.o I oa.o wamoo. 0.0m coco. mqqo. oa.o I mo.o we. om.m mm.a HNHoo. 0.00 ammo. mmmo. mo.o I 00.0 +m «xm Ange ma mum>mv nu. mm.m Hm.H I- I- wmusQEOU “on .H v a mucmamuuafi .mm vmoa vfiamu N m + *« m.m muamfim mum Aafie ma >um>mv mu. om.m Hm.H I- I- causaaoo ”on .H v a muamEouoaH .Nm vmoa canny H m 73 95 surchar e Water content, 2 1F I'll II! 140 160 180 200 220 240 ‘r 1‘— I I § ‘r % ‘ éééesi ‘ o -J O O O 000 0 up- 0 upper O 0 90—?— Sludge 0 layer 0 O ‘ o oo o o C) C) o 8 8 o u . OJ 0) 1H 8 V- H 00 o 3 85- I: \an‘ ‘3‘: N 3\‘S:' axis? 3 _‘_:._'__ Q o g} l C) C) l -lower sludge O G d layer 009. o 80“" “ 57§357FZ “‘sandfi «- \‘i 3'“. \ 75VQQ§5K average water contents: upper sludge layer - 189. Z *' lower sludge layer - 164.2 75*- Water contents of the sludge in the landfill at the end of consolidation. Figure 5.1. 74 4.5 "" (a) Sample U-3-10 4.0 _ e0=5.35 C = 1.70 c Q) .2 3.5 —— L) CO H 'o -.-I O > 3.0 _— 2.5 ——— 2-0 III! I 0.1 A 0.015 wI o _ o c . o from sq. root time curve 44°F! c: 5:? 336? 0.010 _ (b) H.4 : ~ :fl 8 H from log time curve ° 0!: “ A o o > Lac) 0 . 0 A C) 0.8 G) o -H 4.) CO H 8 -H 0.7 (I) >.m u “3’. “*0 0.6 lllll 1 IIIIIIII l I 0.1 1.0 Pressure, pkg/cm2 Figure 5.2." Consolidation characteristics for sludge sample U-3. (a) Void ratio, e. (b) Coefficient of consolidation, cv (c) Primary compression ratio, r. 75 . Eo\wx w.o-q.o ucosouocfi omou Acv . Eo\wx N.oIH.o ucosmuucfi 000 com ooq com com OOH mmoq Amv .meflu mo asuwumon momum> mcwommu Hugo cowmmmuano .m.m muowwm I . 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O 82.6 § umXCNHQ UCQW D mwhmsowsm HHom Nm ON ON ON OH NH O .—I O N 'Bap ‘oanelodmol apelfiriuao '33 ‘oseq aAoqe 38pn13 go uorquatg 104 .ummmH mwODHm umsoH .mmmmmuum HmuOu HmUHuHm> can HmuCONHHom .qH.m mustm cowumunHHmo Oamm 1. .1 4 , Law whammmua HmuOu Hmowuuw> JP— coHuwunHHmo “mums IIII\3 I Z / I S mummmmua Hmu0u HmucouHuo: nu COHumuOHHmu Ocmm :III/ 1v I9 In; . I O TIiwII, JIII. 4w. . . TIAVIII IIIAVI o 0 mm” IOHumunHHmu umumz.ll\\ dVL TIAVIII I». we mudmmmua whom 4 mkmv .mEHH ww Tim; . _ M . . _ H u 0mm oqm OHN om. n. on. om. om ow om HHmu musmmmua HmuoH C) I\\\‘o\ I mmesHm § umxcmHn Ocmm mwumsuusm HHom @U MR\\\\N OH OH NH OH O H O N :sd ‘eznssaxg '3; ‘aseq aAoqe aBpnIS go uorneAaIg CHAPTER VI INTERPRETATION OF RESULTS The discussion and interpretation of results includes both laboratory and field data. The material is presented in three sections, including: (1) sludge placement, (2) engineering characteristics of the papermill sludge, and (3) settlement behavior of the landfill. 6.1 Sludge Placement A wide variety of equipment is available for papermill sludge landfill operations. Equipment selected for the project was based primarily on the contractor's experience with the sludge. The two main factors considered in the selection included the cost of the equipment and its ability to meet the project needs. For example, the placement of the sludge in 10 ft. layers with reasonable uniformity required the use of a dragline that could reach to the central area of the landfill. The dragline was ideally suited to handle the loose bulk sludge where casting and placement were important, and the skill of the operator helped to minimize hand shovel work adjacent to instrumentation. There was no problem with operating space requirements, and a firm support for the dragline was provided by the earth dikes surrounding the landfill. Sludge was delivered to the site from the dewatering facility by a large truck and was dumped either over the dike edge or adjacent to the site. Drainage blankets were placed by dumping sand at the site 105 106 and then distributing it with the dragline and/or dozer. For the top blanket, adequate support was obtained for the dozer from the sand pushed ahead of it. For the middle sand blanket, use of the dozer was avoided because of the possibility of its sinking into the soft sludge and because of the high dike walls at the time of placement shown in Figure 4.5. The sand in this case was placed using the dragline and was leveled by pulling a makeshift drag (two telephone poles tied together) over the surface. Some hand shovel work was required next to instrumentation. 6.2 Engineeringggharacteristics of the Papermill Sludge The engineering characteristics of the papermill sludge are discussed under headings which include (1) physical properties, (2) consolidation behavior, (3) undrained shear strength, (4) stress state in the sludge, and (5) temperature. 6.2.1 Physical Properties The water content of the dewatered sludge is unusually high in comparison to inorganic soils normally encountered in engineering practice. The average water content for the upper sludge layer was equal to 257 percent and for the lower layer was equal to 265 percent for the data summarized in Table 5.2. Both the liquid and plastic limits shown in Table 5.1 tend to decrease for sludge samples with higher ash contents. This correlates with the decrease in water retention when organic content is reduced (Andersland and Laza, 1971). The presence of fibers in the sludge interfered with the mechanical test procedures used to determine the liquid and plastic limits, so that some error may have been introduced in the consistency limits. 107 The volume change and settlement discussed in later sections involves a reduction in water content due to the weight of overlying sludge and surcharge loads. This reduction is reflected in the reduced average water content for each layer shown in Figure 5.1. The scatter of the points shown in this figure can be attributed to sampling from an exposed slope face and to the initial variability of the sludge in the landfill. Specific gravities of the sludge are directly related to the ash content, with the lower values shown in Table 5.1 corresponding to samples containing more organic material. Data in Table 5.1 show that the sludge composition will vary from day to day, with this variation being dependent on operations at the papermill. The average specific gravity for the lower sludge layer, equal to 2.04, is not greatly different from the average for the upper layer, equal to 2.00. This small difference in average specific gravities, together with average water contents which are close for both sludge layers, indicates that initial unit weights should be about the same. The more accurate determination of the sludge unit weight using the weight and volume of a truck load of sludge gave a value equal to 69.7 lb/cu ft. The total unit weight of the sludge at the completion of consolidation, as determined from the undisturbed sample consolidation tests assuming 100 percent saturation, was approximately 72.6 lb/cu ft for the upper layer and 76.5 lb/cu ft for the lower layer. The change from the initial state was small despite the large amount of consolidation that occurred. The greatly increased shear strength of the sludge at the completion of consolidation in combination with this low density 108 suggests that the sludge could be used effectively as a lightweight fill material. 6.2.2 Consolidation Behavior The highly compressible nature of the papermill sludge is shown in Figure 5.2a, where the linear void ratio-logarithm of pressure curve gives a compression index, Cc, of 1.70. This high value for CC is a result of the high organic and high water contents which are character— istic of fresh papermill sludge. Andersland and Paloorthekkathil (1972) have shown the dependence ofICc on these factors. The nonorganic fraction, primarily kaolinite clay, has a compression index close to 0.25 and also contributes to the compressibility of the sludge. The variation in the coefficient of consolidation, cv, with each load increment is illustrated in Figure 5.2b. The square root of time fitting method gives higher values for cv than the logarithm of time fitting method. The change in cv during compression depends on the change in both the permeability and compressibility of the sludge, since cv equals ka . Here, k is the coefficient of permeability; Yw v w is the unit weight of water; and mv is the coefficient of compressi- bility of the soil skeleton, equal to - i—%fE-%§:, where e is the void ratio, and 3.13 the effective stress. It is apparent from Figure 5.2b ‘that the coefficient of permeability for the sludge has decreased more rapidly than the compressibility. This has reduced cv for increasing values of effective stress, as shown in Figure 5.2b. The variation in primary compression ratio, r, with pressure is shown in Figure 5.2c. Compression can be separated into three parts 109 d d d such that B£~+ BE-+-B§ equals unity, where D is the total compression experienced over the load increment and d1, dp, and CIS are the initial, primary, and secondary compression, respectively. In this case, r d equals-—R and is a measure of the amount of compression that occurs D only as a result of pore water expulsion. The variation in r shown in Figure 5.2c is difficult to explain. For larger loads, Andersland and Paloorthekkathil (1972) obtain a fairly constant r with pressure, although there is considerable scatter in their results. The curve in Figure 5.2c shows results typical for all tests run with the Bishop consolidation machine at smaller loads. The drop in r with the second load increment could be due to a reduced hydrodynamic effect associated with the small amount of pressure added after the first increment (0.1 kg/cmz). Since secondary compression is a function of stress level, its effect may increase slightly over the load increment. However, the load increment is so small that hydrodynamic compression due to pore water expulsion may exhibit a reduced effect and secondary compression may become more prominent in the total compression over the load increment. This is shown by the flatter dial reading versus logarithm of time curve shown in Figure 5.3a. As the load increments increase in size, the hydrodynamic effect becomes more dominant and r increases. The high value of r for the first increment (O to 0.1 kg/cmz) may be due to the large amount of deformation occurring over the increment (e changes from 5.35 to 4.51). Figure 5.3b illustrates the curved shape of the logarithm of time curves associated with larger load increments. Figure 5.43 shows the variation in the coefficient of secondary 110 compression, Ca, with effective pressure. There is a slight increase in Cu with pressure, as might be expected because of the greater deviatoric stresses occurring at higher pressures. However, this is somewhat compensated for by the increased density and reduced compress- ibility of the sludge resulting from compression. Andersland and Paloorthekkathil (1972) show a fairly constant Co with effective pressure. Figure 5.4b illustrates the reduction in the ratio Ca lsp with increasing load increment. The results of the consolidation tests on the undisturbed samples of sludge are somewhat different from the results of the tests on the fresh samples of sludge. The e vs. log 3 curves are typical of those that might be obtained from a moderately disturbed normally consol- idated soil sample. Theoretical values of B; have been back-computed from the curves using the Casagrande procedure and are shown in Figure 5.5. Using a sludge unit weight of 72.0 lb/ft3 and an average residual pore pressure of 1.2 psi, the calculated in situ vertical effective stress for the upper layer sample is .301 kg/cmz, which agrees closely with the back-computed values shown. However the lower layer calculated effective stress is .55 kg/cmz, which is less than the values shown for the lower layer in Figure 5.5 (.65 - .77 kg/cmz). This discrepancy, could be the result of using the Casagrande procedure to back-compute 36. Disturbance effects relative to this are discussed below. The pressures computed by the two methods for the lower layer lie close together on the log scale even though the difference in their magnitudes is fairly high. The vertical effective stress calculated in the lower layer from the total pressure cell and piezometer data of Figure 5.14 is 111 .77 kg/cm2 (water calibration), which agrees closely with the back- computed value from the e vs. log 5 curve. However it is the author's opinion that this pressure is too high, primarily because of the increase in measured total pressure exhibited by the pressure cell after surcharge application. If the value of total pressure measured at the completion of surcharge application is used to compute the in situ stress, a value of .65 kg/cm2 is obtained. This discrepancy is discussed further in a following section on the stress state in the sludge. Since the sample obtained from the lower layer was under a greater in situ effective stress than the upper layer, it would be expected that the lower layer would have a lower initial void ratio and higher back-computed 3;. The difference in Cc between the two sample locations is likely a result of the non-homogeneity of the sludge in the landfill. Somewhat higher ash contents were present in the lower sludge layer, which would help to account for this difference. The high values of cv at stresses below the effective overburden pressure shown in Figure 5.6a are related to the sample disturbance and are difficult to physically interpret. As Terzaghi and Peck (1967) point out, a perfectly undisturbed sample recovered from the ground would be subjected to an all around capillary pressure with an intensity of approximately 0.7 to 0.9 times the effective overburden pressure. ‘If this sample were to be loaded in an oedometer to a stress level less than this, it would theoretically have to swell to reach equilibrium under the lower effective stress. The addition of load at this lower stress level would then cause the sample to follow a reload 112 curve until the initial in situ conditions (e0, 36) were again reached. Since there is always some degree of disturbance that occurs in sampling, however, a good undisturbed sample will usually result in a flat curve below 36, similar to that shown in Figure 2.3. The relatively high degree of disturbance of the sludge samples caused a breakdown in the capillary pressures and, as a result, the samples were consolidated when subjected to stresses below the effective over— burden pressure. The resulting compression occurred rapidly until equilibrium was reached, yielding high values of cv. The e vs. log 3 curve does not represent a reload curve in the usual sense, as no swelling occurred, and its shape would change depending on the degree of sample disturbance. Thus the observed compression below 3; can be quite variable, and the resulting values of cv, Ca’ and r can be affected. The low primary compression ratios below 36 in Figure 5.6b indicate that creep of the soil skeleton is a significant portion of the measured deformation in this stress region. The reduced hydro- dynamic effect associated with this can be related to the capillary and disturbance effects discussed above. The values of the coefficient of secondary compression shown in Figure 5.6c are also smaller at low stresses, indicating that the field consolidation has increased the resistance of the soil skeleton to creep deformation. The magnitude of Ca increases steadily over the entire stress range and approaches that of fresh sludge at the higher pressures. The sample from the lower layer has values of Co which are somewhat less than the upper layer, again indicating reduced compressibility of the soil skeleton due to the higher consolidation pressure. 113 6.2.3 Undrained Shear Strength The undrained vane shear strengths summarized in Figure 5.7 show a large dependence on the degree of consolidation. The slightly greater initial strength in the upper layer (ll/ll/7l) as compared to the lower sludge layer (10/14/71) can be explained by the lower average initial water content (footnote, Table 5.2) in the upper layer. The increase in strength with depth shows up with only partial consoli- dation. Laboratory data (Andersland and Laza, 1971) show a linear relationship between undrained strength and consolidation pressure. Sensitivity of the sludge in terms of the ratio of the undisturbed to remolded strength is small, ranging from about 1.5 to 2.5. This is comparable to that for many inorganic clays (Terzaghi and Peck, 1967). Very significant increases in strength have occurred in 3-l/2 months, as shown by data obtained on 3/20/72. Most of this improvement in strength presumably occurred during primary consolidation. There was also a strength increase after this period, as shown by the data in Figure 5.7b. Secondary compression could be responsible for a large portion of this increase. According to recent data presented by Bjerrum (1972), the vane shear strengths summarized in Figure 5.7 do not represent the actual field undrained shear strengths needed in a slope stability analysis. Bjerrum (1972) recommends that the vane shear strengths be adjusted according to the relation (6.1) (Su)field = (Su)vane u where su is the undrained shear strength and u a parameter which is 114 dependent on the plasticity index. For the sludge plasticity index of about 150, Bjerrum's (1972) chart gives a value of u - 0.6. A comparison of (su)vane. p values with preliminary laboratory undrained triaxial data gives reasonable agreement. 6.2.4 Stress State in the Sludge Both the vertical and the lateral total stresses recorded on the total pressure cells (Terra Tec model T-9010) located near the middle of the lower sludge layer are summarized in Figure 5.14 for the period covering sludge placement, surcharge loading, and consolidation. Values determined from the water calibration curve are probably on the low side, with the real pressures falling between the water and sand calibration curves. As consolidation proceeded after completion of the. landfill, the horizontal pressures decreased while the vertical pressures increased. This increase is contrary to what would be expected because as water drains from the sludge and leaves the area, the total vertical pressure should decrease. It is presumed that this peculiar behavior is due to certain limitations of the total pressure cell. Subtraction of the pore pressures (piezometer G7-3) from the total pressures gives the effective stresses. Taking the ratio of the effective horizontal to vertical stress gives an estimate of the coefficient of lateral earth pressure, Ko' After completion of the lower layer, measured values of K0 were .63 (water cal.) and .68 (sand cal.). Immediately after surcharge application these values were reduced to 0.38 and 0.48, respectively. For the final stages of consolidation the values for K0 dropped to 0.30 (water calibration) and 0.34 (sand 115 calibration). These final values of K0 should approximate normal consolidation of the papermill sludge. Since the stress-strain relation shown in Figure 6.1 for papermill sludge does not exhibit a peak, the determination of a friction angle, 3, requires that a somewhat arbitrary failure strain (thus stress difference) be assumed. Andersland and Laza (1971) assumed 20 percent strain as failure and calculated a friction angle of approx- imately 570 for the sludge. This would correspond to a KO value of .16 using the empirical relation, KO = 1-sin $3 for normally consolidated inorganic clays (Lambe and Whitman, 1969). Although this does not agree with the field value of K0, a smaller assumed failure strain would result in a KO value that would be more consistent with field observations. Since the stress-strain curve has a break in it at approximately 3 percent strain, anything above this value could conceivably represent ”failure." Thus it is possible to compute, from the field value of K0, a friction angle for the sludge equal to 430 that could be argued to be theoretically correct. These results indicate the limitations involved in estimating the in situ lateral effective stresses in papermill sludge. 6.2.5 Temperature Temperatures at various levels in the sludge landfill, with corresponding dates, are summarized in Figure 5.13. Difficulties with the installation of the thermistors delayed the initial temperature readings until about 1 month after placement of the surcharge load. The temperature rise due to increased biological activity appears to have peaked about 50 days after completion of the landfill. The maximum 116 temperature rise of about 70C occurred in the upper half of the lower sludge layer. Subsequent winter weather reduced the sludge temperatures at all levels until spring and summer, when the seasonal warming effects prevailed. During January and February, when average monthly air temper— atures were close to zero degrees centigrade, sludge temperatures ranged from about 3°C near the surface to 20°C in the bottom sand blanket. Warmer spring air temperatures decreased this range in temperatures, and in the early part of August the colder temperatures were near the bottom of the landfill. The warmer summer temperature, plus a period of low rainfall, appears to have influenced the pore pressure readings shown in Figure 5.12 for the upper portion of the t0p sludge layer. This will be discussed in a later section on pore pressure dissipation. Although it has been shown that temperature can alter the equilibrium void ratio, coefficient of consolidation, coefficient of secondary compression, and primary compression ratio (Andersland and Paloorthekkathil, 1972), its effect has not been incorporated into any practical consolidation theory and thus it can be included in an analysis only qualitatively. The variation in the parameters mentioned above was found to be small for a temperature range of 6°C to 38°C, so any temperature changes occurring in the landfill (assuming no dessi- cation) would have only a slight effect on its behavior. Temperatures were not measured in the landfill during construction or for the first month after surcharge placement, so data covering the period of primary compression are absent. 6.3 Settlement Behavior of the Landfill The settlement behavior of the landfill is discussed under two 117 headings: the upper sludge layer and the lower sludge layer. Both sections include information on (1) loading and general field observa- tions, (2) ultimate settlement, (3) time-rate of settlement, and (4) pore pressure dissipation. 6.3.1 Upper Sludge Layer 6.3.1.1 Loading and Field 0bservations.--The upper sand blanket and earth surcharge provided a total applied load of about 490 psf on the surface of the upper sludge layer. This load was applied in a period of about 4 days (Figure 5.8), with most of the surcharge placement occurring on the last day. This loading rate approximates an instantaneous loading condition. Because of the landfill area involved, the resulting settlement is due to drainage and compression in the vertical direction only. The similarity of time-settlement curves (Figure 5.8) between instrument groups supports this fact. Any difference in the ultimate settlement between groups can be attributed to small differences in load application (maximum t 3 inches in surcharge thickness) and nonhomogenity of the sludge, with respect to water content, occurring during placement (Table 5.2). The major difference involved instrument group 7, where excess settlement occurred because soil for the surcharge was piled there prior to spreading with -a dozer. The square root of time and logarithm of time versus settlement curves (Figures 5.9 and 5.10) for the upper sludge layer provide infor— mation on the amount of primary and secondary compression, the coeffi- cient of consolidation, cv, and the coefficient of secondary 118 compression, Ca' The square root of time curves in Figure 5.9 were prepared on the assumption that the initial point (commencement of compression) occurred at the completion of surcharge placement. The bend in the upper portion of the curve results from the fact that about 3 inches of settlement occurred at most instrument groups during surcharge load placement. However, the assumed initial point gives an average Cv’ equal to 0.0626 inz/min for 90 percent consolidation, that is in agreement with the logarithm of time curves (Figure 5.10) and the pore pressure dissipation curves (Figure 5.12). The logarithm of time curve fitting method shows that primary settlement was complete after about 750 hours, and was then followed by secondary compression. Primary compression is rate controlling and determines the shape of the curve only during the initial stages of settlement because it occurs more rapidly than secondary compression. Using the time-settlement curves for instrument group 6 (Figure 5.8f) as representative of the sludge landfill, primary compression is computed to be 16.7 inches and secondary compression, 4.1 inches (for a total t a 238 days). The pore pressure dissipation curves (Figure 5.lld) confirmed that primary compression was essentially complete at about 34 days. The decreasing secondary compression rate, shown in Figure 5.10, is not in full agreement with the laboratory curves shown in Figure 5.3. The laboratory curves showed a linear relation between settlement and logarithm of time after a relatively short transition curve. The settlement experienced over the last time interval shown on the settlement versus logarithm of time curves for the upper layer 119 (Figure 5.10) was larger than expected. This was due to a drying of the upper half of the layer as a result of high summer temperatures and low rainfall. As shown in Figure 5.12c, piezometer 05-8 exhibited a large reduction in pore pressure over this time interval. Calculations showed that approximately 65 percent of the total settlement over this interval occurred in the upper half of the layer. Thermistors l and 3 (Figure 5.13a) showed increased temperatures in the upper half of the upper sludge layer at the time of the last reading (t = 327 days). To illustrate the correlation between landfill settlement and leachate drainage, a comparison has been made, in Figure 6.2, between the measured leachate flow rate, Qm, at the drainage pipe outlet shown in Figures 4.1 and 4.3 and the calculated flow rate, QC, based on the slope of the time—settlement curves (Figure 5.8). All but one of the points shown give QC greater than Qm' This would be expected because the drainage system was not constructed to be leakproof and leachate was undoubtedly lost into the dike and the material surrounding the pipe. The point shown for 11/12/71 was calculated from the slope of the time—settlement curve for the lower layer only, since the upper layer was not yet completed. Because leachate was draining from the upper layer also, the point should be displaced to the right to be more accurately located. It was assumed that for the upper layer one half of the flow went to the top of the layer and the other half to the drainage pipe. Despite the uncertainties involved in the flow rate measurements, the correlation to the settlements is fairly good. Heavy rain after December 1, 1971, caused infiltration of rainwater into the pipe and flow rates measured at the pipe outlet increased considerably. 120 6.3.1.2 Ultimate Settlement.--For plastic clays and organic sciis (including papermill Sludge) the/Eltimate settlement estimate must include both primary and secondary compression. When data are not available from previous experience, the parameters needed for a settle— ment analysis are obtained from laboratory tests and extrapolated to field behavior. The following discussion reviews several procedures for estimating ultimate settlement and applies them to the experi- mental sludge landfill. ' A common method for estimating ultimate primary settlement uses .- the stress-strain relation Cc 6f 6 77:10am: - . (6'2) 0 O ‘ . ds . ‘ . . . . where c =‘d; is the vertical strain at a pOint, CC the compreSSion index, eO the initial void ratio, a; the initial effective normal vertical stress, and 3f the final effective normal vertical stress. Equation 6.2 is an extension of equation 2.1. 'The total or ultimate primary settlement, AH,,for a sludge layer of initial thickness, H, can be found by integration. H __.‘ ‘ ‘ CC 'Of _' V . S = AH = g ———'e—— log 10 '5..— dZ (6.3) O 0 Application of this equation to in situ soil layers is straightforward since the soil is in static equilibrium with a fixed groundwater table, 'which readily permits the computation of changes in effective vertical stresses. However, in the sludge landfill the presence of excess pore 121 pressures both before loading, due to the weight of overlying sludge, and after completion of primary compression, a residual pore pressure assumed due to an insufficient gradient for flow, complicate computation of the effective stresses. The procedure followed in the application of equation 6.2 is illustrated in Figure 6.3. The initial effective stresses in the sludge after placement of the upper sand blanket are given in Figure 6.3a. Pore pressures represent field data from instrument group 7 just prior to surcharge loading. The sand blanket was not yet placed at other instrument groups when these data were obtained. Total vertical stresses were computed using a constant sludge unit weight equal to 70 pcf. Initial void ratios were taken from a laboratory e - log 3 curve at the effective stresses, 5;, shown. Final effective vertical stresses are given in Figure 6.3b. That portion of the final stresses due to the overburden weight of sludge and sand is actually different from those shown by an amount dependent on the decrease in the sludge water content. This effect would be to reduce the overburden pressure. For this analysis it was assumed that this reduction in overburden pressure would not greatly alter the results. Subtracting the residual pore pressure in Figure 6.5 from the total stresses in Figure 6.3b gave the final effective normal stresses. Substitution of the stresses from Figures 6.3a and 6.3b into equation 6.3 gave the strain values shown in Figure 6.3c.' Integration of this strain over the thickness of the upper sludge layer provided an estimate of the ultimate primary settlement equal to 18.1 inches. Since this value is close to the observed primary settlement of 16.7 inches, use of equation 6.2 appears to be justified. For design purposes the use of equation 6.2 will be somewhat limited, since no methods are available for predicting 122 residual pore pressures. Initial pore pressures generated during sludge placement can be estimated by the procedure discussed in the next section. The accuracy of the analysis shown in Figures 6.3 and 6.12 can be seen from Table 6.1. Here the settlements calculated from the assumed strain distribution are compared to the actual settlement of the upper and lower halves of the two sludge layers. The end of primary compression for the field calculations was taken from the pore pressure dissipation curves (Figure 5.12), and the total primary settlement at this time was found from the settlement-time curves (Figure 5.8). Any settlement of the plates located at the mid-point of each layer that occurred prior to completion of the sludge layer had to be subtracted from the total primary settlement because the strain analyses of Figures 6.3 and 6.12 have initial conditions that occur after completion of the layer. The analyses appeared to underestimate the settlement of the lower half of each layer and overestimate the settlement of the upper half, with the actual settlement corresponding to a nearly constant strain condition. MacFarlane (1969) has proposed that the ultimate primary settlement in peat be computed on the basis of the equation where AHf is the total primary settlement of a peat layer in the field, Ho the initial thickness of the peat layer in the field, AHL the f initial compression of the laboratory sample, and Ho the initial L 123 thickness of the laboratory sample. This method required that a repre— sentative laboratory sample be tested in an oedometer under an increment ‘of load equal to the load applied in the field. The average unit strain in the laboratory specimen is then equated to the average unit strain in the field peat layer to obtain the settlement. An average primary settlement of 19.4 inches was obtained using average data from 5 labora- tory tests with an applied load equal to 3.4 psi (weight of sand blanket plus soil surcharge). This method overestimates the actual primary settlement by about 2.7 inches. The validity of equation 6.4 is dependent on several factors including (1) the selection of a fully representative laboratory sample,.(2) the preparation of the.laboratory sample at a representative average initial void ratio for the layer, and (3) the different strain rates for the laboratory sample as compared to the field. 0 Secondary compression may be estimated on the basis of the equation (MacFarlane, 1969) ._. 't_ AHS Hpca loglo t P (6.5) where AHS is the settlement due to secondary compression, Ca the coefficient of secondary compression equal to the strain (relative to Hp) occurring over one cycle of the secondary portion of the settle— ' . ment-logarithm of time curve, t the field time considered, tp the estimated field time for primary compression, and Hp the thickness of the sludge layer at time tp. Using a laboratory value of cv equal to 0.017 inZ/min to calculate tp equal to 103 days, and using a laboratory value of Ca equal to 0.0150 gives an estimate of AHS equal to 0.4 inch 124 for a t equal to 176 days (total t = 238 days). When a more realistic value of tp equal to 34 days is used, the secondary compression becomes 1.0 inch. Since the actual secondary compression is close to 4.1 inches, the laboratory value of Ca appears to be too low. Gibson and Lo's (1961) theory can be used to estimate the ultimate settlement of the upper sludge layer by the use of equation 2.9. Substituting the parameters shown in Figure 6.4 into this equation, with qo equal to 3.4 psi and H equal to 120 inches, gives an estimate of ultimate settlement equal to 22.4 inches for the upper sludge layer. Primary compression, represented by (a - qo - H), equals 20.3 inches and secondary compression, represented by (b ° qo - h), equals 2.1 inches. Although the primary compression has been overestimated and the secondary compression underestimated, the total compression estimate appears reasonable. This method is subject to the same uncer- tainties in extending laboratory test data to the field prediction of settlements as was discussed earlier. 6.3.1.3 Time-Rate of Settlement.-—Time-rate of settlement predictions involving primary consolidation are generally based on the Terzaghi (1943) consolidation theory. This theory involves the solution of the differential equation _= c __ (6.6) where u is the excess pore water pressure, t the time after application of load, 2 the distance from the mid—point of a doubly drained stratum, and cv the coefficient of consolidation. The solution of equation 6.6 for various boundary conditions is given by Terzaghi (1943), Leonards 125 (1962) and others. The degree of consolidation, U, for a given time, t, is commonly expressed as some function of the time factor, Tv’ equal to 4Cvt/HZ. The use of this theory in estimating the time settlement relation for the upper sludge layer is illustrated in Figure 6.6. Since this theory cannot model secondary compression, it has been used in combination with equation 6.5. Here tp was taken as the time at which 92 percent consolidation was theoretically reached (TV a 1.00). Using MacFarlane's (1969) method, the total primary compression was taken equal to 19.4 in. and the secondary compression equal to 0.4 in. This procedure relies on laboratory data and can be considered representative of a design estimate. Curve (:> in Figure 6.63 shows the observed time-settlement relation for instrument group 6 in the landfill, and curve <:> gives the time-settlement relation using Terzaghi's theory and parameters based on the field data. Curve <:> considers primary compression equal to 16.7 in. and secondary compression equal to 4.1 in. (Ca - 0.0556). The laboratory parameters give an underestimate of the time-rate of settlement. Part of the discrepancy between actual and calculated curves results from the assumption that the theoretical curves start after completion of surcharge placement whereas the field curve begins earlier. A plot of settlement versus logarithm of time for curves (:> and (:> is shown in Figure 6.6b. This figure illustrates how the secondary portion of the field curve is concave upwards, as compared to the linear secondary portion of the theoretical curve. This would indicate that the field compression curve exhibits Type I (Lo, 1961) secondary compression. However, as mentioned earlier, the laboratory curves, even with one 126 3.4 psi load increment recorded for a week, did not indicate this behavior. The lower layer also exhibits this upward curvature in the secondary range. However, the field pore pressures indicate that slow pore pressure dissipation is still occurring in this layer, and so this curvature may be part of the transition zone between the primary and secondary compression regions. Gibson and Lo's (1961) theory has been used to obtain the theoretical time—settlement curves shown in Figure 6.6c. Curves for three different values of cv have been plotted, none of which closely follow the actual field settlement curve over the entire range of time. Part of the difference results from the predicted ultimate settlement being slightly larger than the actual settlement. At times up to approximately 300 hours, the theoretical curves for the two higher values of cv are closely parallel to the field curve, but between 300 and 1000 hours the settlement predicted from theory increases at a faster rate than the actual settlement. For the given parameters, Gibson and Lo's (1961) theory predicts that the ultimate settlement is reached very rapidly, without the development of a linear (with log time) secondary compression curve. The theoretical type of secondary compression that develops from this theory is dependent on the value of a parameter, N, equal to H2/%~b°cv. Values of this parameter for the sludge landfill are large (700 for cv - .063 inZ/min) and result in the theoretical curves shown in Figure 6.6c. For N values of approximately .04, secondary compression occurs for a much longer period of time. The low value of the viscosity measured in the laboratory (6.95 x 104 lb/inz/min) appears to be the soil property largely responsible for the theoretical results obtained, being on the 127 order of 102 to 103 times smaller than values obtained from clays tested by Gibson and Lo (1961). The dependence of the development of secondary compression on layer thickness is apparent from N, which helps to explain the difference between the lab and field secondary compression behavior. Wahls's (1962) theory has been used to obtain the two theoretical curves shown in Figure 6.6d. As discussed in Chapter II, AH in equation 2.18 represents primary settlement only, and since Wahls's theory assumes that secondary compression can occur simultan- eously with primary compression, it is necessary to establish a value of AHp from the parameters given. This was done by assuming an initial value of primary settlement equal to 16.7 in., obtained from field settlement and pore pressure data, and subtracting from this the theoretical amount of secondary compression that occurred during the time necessary to reach this amount of settlement (assuming Tv - 1.0 for the end of primary compression). This can be computed as AHp 8 16.7 - (.0147)°(103)-(.8684) = 15.4 in. Here 0.0147 = assumed Ca 103 = Hp, and 0.8684 = h(Tv). Thus the time settlement relation is given by AH(t) = 15.4 f(Tv) + (103)(.0147) h(Tv) (6.7) The results obtained from Wahls's theory are similar to those that were obtained using Terzaghi's theory. The back computed field value of cv (.0626 inz/min) accurately models the settlement up to the end of primary compression, and the laboratory determined value of Ca(.0147 in2/min) appears to be too low. A larger value of Co would accurately model the settlement for only a limited time because Wahls's theory 128 assumes a secondary compression rate that is linear with log time while the field secondary compression rate is decreasing with log time. Since Wahls's theory includes secondary compression in its mathematical formu- lation, it results in a smoother curve in the transition region than the method that was used to model secondary compression with Terzaghi's theory. Assumptions in Terzaghi's theory which may cause deviation from the field results have been discussed in Chapter II. In addition to these, Terzaghi's theory also assumes that the soil is fully saturated. Any gas present in the sludge prior to surcharge application would be compressed on application of the load, giving an immediate settlement. This may be responsible for part of the 3 in. of settlement which occurred during surcharge placement. Pore pressures generated upon loading (Figure 6.7) are less than the applied load, indicating that there was partial dissipation during this loading period. 6.3.1.4 Pore Pressure Dissipation.—-Use of equation 6.2 for estimating total primary settlement requires information on initial pore pressures. The pore pressures shown in Figure 6.33 resulted from stresses induced by the sand blanket and weight of the sludge. Pore pressures resulting from the placement of the sand blanket were assumed equal to its load (100 psf) throughout the layer. Initial pore pressures resulting from the sludge layer increasing in thickness with time were estimated using Gibson's (1958) theory. Pore pressures from this theory are presented in Figure 6.8 for both laboratory and field values of cv, along with the measured pore pressures. The observed pore pressures fall between the predicted values, with the exception 129 of the 30 in. depth. No duplicate piezometer readings are available for this depth, hence a recording error or malfunction is possible. The 115 psf pore pressure in the middle sand blanket may have influenced the value at the 90 in. depth. Except for these factors Gibson's (1958) theory appears to accurately predict pore pressures generated during sludge placement. Pore pressure dissipation during placement of the sand and surcharge load appeared to be responsible for Au/Ap values less than unity, as shown in Figure 6.7. The pore pressure increase at the center of the layer ranged from 94 to 99 percent of the applied load, whereas at the 1/4 point pore pressures were about 85 percent of the applied load. The [Edata point for group 7 in Figure 6.7b represents only the surcharge load, whereas for the other groups the pore pressures include application of the sand plus surcharge load.) Adding a 100 psf load due to the sand layer for group 7 gives a point very close to Au/Ap equal to unity, as shown by the second point. Residual pore pressures summarized in Figure 6.5 represent data from the pore pressure versus time curves in Figure 5.12. The data in Figure 6.5 represent average values of ur obtained from these curves. Piezometer 8 in group 5 appears to have a reduced pore pressure at 327 days due to drying of the earth surcharge and the upper portion of the upper sludge layer during a relatively dry summer. The fluctuation in pore pressures after 90 days appears to be due to measurement devia— tions and environmental effects, such as seasonal wetting and drying. Pore pressures in the middle sand blanket are the result of the sand forming a bowl shape because of less settlement along the periphery of ~the landfill, thus holding water up to a certain elevation. 130 The field pore pressure dissipation curve at the mid—point of the upper sludge layer in instrument group 6 is compared, in Figure 6.9a, to computed curves based on Terzaghi's (1943) theory. The initial excess pore pressure used for computation was assumed equal to the difference between the maximum and residual pore pressures. The labora- tory value of cv (0.0170 inz/min) gives pore pressures substantially higher than the observed pore pressures during the consolidation period. Using the cV (0.0626 inz/min) value based on field data, Terzaghi‘s (1943) theory slightly overestimates the pore pressures (curve 3) up to about 70 percent dissipation and thereafter gives an underestimate. The slower dissipation rate occuring after about 70 percent dissipation was also observed in the laboratory by Andersland and Paloorthekkathil (1972). The pore pressures predicted from the theory of Gibson and Lo (1961) are in close agreement with those of Terzaghi, as shown in Figure 6.9b. The decrease in pore pressure dissipation rate after 70 percent dissipation may be the result of non-Darcy flow in the sludge. Mitchell and Younger (1967) discussed this effect in detail and concluded that there are indications that deviations from Darcy's law exist in many fine- grained soils subjected to low hydraulic gradients but that not much direct field evidence is available concerning seepage or consolidation to corroborate this effect. The recorded field dissipation curves (Figures 5.12 and 6.9) indicate that non-Darcy flow does exist in the sludge landfill and that this flow precedes the formation of residual pore pressures in both sludge layers. These residual pore pressures imply the existence of a threshold gradient in the sludge below which no flow occurs. For a threshold gradient, 10, drainage will occur 131 only when du r i>i=__l.d o Yw z (6.8) where i is the existing hydraulic gradient, ur the residual pore pressure at depth 2, and Yw the unit weight of water. If this gradient can be considered a constant property, then integration of equation 6.8 will give a theoretical distribution of the residual pore pressures shown in Figure 6.10. The observed residual pore pressure distribution summarized in Figure 6.5 is influenced by the pore pressures in the middle sand blanket. If the pore pressure in the sand blanket was reduced to zero, as it would be if complete drainage were possible, and if the value at the lower one—quarter point was reduced, the resulting distribution would likely agree with theory. Assuming that the theory represents the field conditions, using the maximum residual pore pressure at the center of the layer gives a value for 10 equal to 0.885. Below this gradient primary consolidation will cease, with no additional dissipation of pore pressures, Reasons quoted by Mitchell and Younger (1967) for the development of non-Darcy flow and a threshold gradient include: (1) resistance to flow caused by cations in the electrical double layer surrounding the clay particles, (2) particle movements leading to reversible void plugging and unplugging, and (3) the existence of a quasi-crystalline adsorbed water (leachate) structure. If any of these reasons apply to papermill sludge, the author believes that (3) would best help explain the development of a threshold gradient. Since the existence of such a gradient implies a no—flow condition it would seem 132 necessary for the water (or leachate) to develop a quasi—crystalline structure that could be considered as solid below the threshold gradient. Grim (1968) also favors this quasi-crystalline concept to explain the clay—water system. It should be noted that the chemical makeup of the leachate and the presence of large amounts of organic material in the sludge could have a marked effect on the leachate flow properties at low gradients. Andersland and Laza (1972) observed that a threshold gradient was required to initiate flow in the sludge only in the case of low backpressures, and that when the undissolved gas in the pore fluid was reduced to zero this gradient was not necessary. Such a result would indicate that gas generation in the sludge contributes to the reduced leachate flow rate and residual pore pressure formation observed in the landfill. In addition, there might also be chemical interactions between organic compounds in the leachate and the clay particles, such as the adsorption of polar organic molecules onto the surface of the clay. Chemical reactions such as this might also lead to the development of a threshold gradient. The pore pressure dissipation and time-settlement curves predicted from Terzaghi's (1943) theory are based on the assumption of a uniform initial excess pore pressure. Because deviations from this assumption can cause changes in the dissipation-settlement relations, its validity is examined in Figure 6.11. From this figure it can be seen that the increase in pore pressures from their initial values to the maximum values generated under the applied loads is fairly uniform. Since the residual pore pressures are relatively close in magnitude to the initial pore pressures, the assumption of a uniform initial excess pore pressure in-Terzaghi's theory appears to be valid. If the 133 residual pressures were much different from the initial pressures, then the condition of one-dimensional consolidation would best be analyzed with water flow controlled by v = k(i - 10), where v is the velocity of flow and k is the coefficient of permeability. This condition is described by Mitchell and Younger (1967) and the inclusion of a threshold gradient in the consolidation process is covered by Janbu (1965). 6.3.2 Lower Sludge Layer 6.3.2.1 Loading and Field 0bservations.--The lower sludge layer supported an applied load of about 1290 psf from the weight of the middle and upper sand blankets, the upper sludge layer, and the earth surcharge. The upper sludge layer was placed at a fairly constant rate over a period of about 30 days. The settlement and pore pressure changes observed in the lower sludge layer are summarized in Figures 5.8 and 5.11. Pore pressures were generated in the lower sludge layer during placement of the upper sludge layer, however, some dissipation and settlement also occurred concurrently with this sludge placement. The surcharge placement induced an immediate increase in pore pressures throughout the lower sludge layer, followed by their dissipation and the resulting curved time-settlement relation. The logarithm of time and square root of time curve fitting methods used in a settlement analysis assume an instantaneous appli- cation of load. In the case where loads are increased at some rate, such as for the lower sludge layer, these curves are of limited value. The logarithm of time versus settlement curves for the lower sludge layer in Figure 5.11 provide information on the secondary compression 134 behavior of the sludge. The curve appears to show a decreasing secondary compression rate rather than a constant rate. The charac— teristic S-shape for the entire curve has been flattened due to the gradually increased load resulting from sludge placement of the upper layer. Separation of the settlement into primary and secondary portions is more difficult for the lower sludge layer. The square root of time fitting method cannot be used. 6.3.2.2 Ultimate Settlement.-—The ultimate primary settlement of the lower sludge layer is computed to be 32.8 inches in Figure 6.12, using equation 6.2. The procedure is the same as described for the upper layer, with Figure 6.12a giving the stresses in the sludge after placement of the middle sand blanket and Figure 6.12b the stresses after application of the surcharge. Since the lower sludge layer has been subjected to larger effective stresses for a longer period of time than the upper layer, the amount of secondary compression should be greater. If 7 inches is assumed for secondary compression, based on the same primary compression ratio as for the upper layer, this leaves about 29 inches for primary compression. This means that equation 6.2 overestimates the primary settlement, but considering all the assumptions involved, this estimate appears reasonable. A check on the total stresses calculated at the mid-point of the lower layer in Figure 6.12b can be made using the total pressure cell data from Figure 5.14. The calculated total vertical stress at the mid-point is 1740 psf (12.1 psi) whereas that shown in Figure 5.14 varies from 11.8 to 13.2 psi (water calibration). Since the slow increase in total vertical stress measured by the pressure cell cannot 135 be explained, it is assumed that the actual stress falls between 11.8 and 13.2 psi, giving support to the calculated value of 12.1 psi. A consolidation test using a single load increment equal to 1290 psf (0.63 kg/cmz) was carried out on a sludge sample from the lower layer to provide a basis for estimating the ultimate primary settlement by MacFarlane's (1969) method. Using data from test No. L—2—4 in equation 6.4 gives a value for primary settlement equal to 35.3 inches. This value is closer to the actual field settlement of 36 inches, which includes both primary and secondary settlement. It is possible that the high initial void ratio of the laboratory sample, greater than the average initial in situ void ratio of the field layer, permitted greater volume change than is representative for the sludge layer. It is difficult to determine from the field data the exact amount of secondary compression in the lower sludge layer. For analysis purposes a value of Ca equal to 0.0556 and a tp equal to 26 days (total t = 60 days) were used in equation 6.5. For H equal to 94 inches a value of 4.7 inches was obtained for the secondary compression for t = 204 days (total t = 238 days). The use of a value of Ca back- figured from the upper layer along with a tp equal to 26 days, appeared realistic in light of the high amount of primary consolidation that occurred throughout most of the loading period. The value of 4.7 inches of secondary compression appears low based on results from the upper sludge layer. 6.3.2.3 Time-Rate of Settlement.--A theoretical estimate of the time—settlement relation for the lower sludge layer requires that the loading be represented by the numerical procedure shown in 136 Figure 6.13. The placement of the upper sludge layer and upper sand blanket has been modeled as an applied stress linearly increasing with time, and the surcharge has been represented as an instantaneously applied stress. Equation 6.6 is placed in finite difference form (Barr, 2 1966) with gg-and 8 3 becoming t 32 g2.= lim ”(21’ tj+l) ‘ “(21’ t3) _ ui,j+l ’ “1,j (6.9) at At+0 At ‘ At and 82u a ui+1,j ' 2Ui,j + “1-1,j (6.10) 322 (A2)2 Substituting these expressions in equation 6.6 gives (1 — 2s) + (u a (6.11) ui,j+1 ’ ui,j i+l,j + “1-1,j) c At 2 (AZ) time increment, Az equals H/8 (H is the thickness of the layer), and where a is and is assumed equal to 1/6 (Scott, 1963), At is the cv is the coefficient of consolidation. Using the time factor Tv equal to Cvt/(H/2)2, and a equal to l/6, results in a value for ATv equal to 1/96. To model the linear stress, a unit initial pore pressure (stress) is first applied throughout the layer. This is allowed to dissipate over the interval ATv equal to 1/96, at which time another unit of pore pressure is added to obtain a new pore pressure distribution. This process is repreated over the required number of increments (n) as shown in Figure 6.13, where n is defined as t equal to cv(ts)/a(Az)2, and t8 is the time at which the surcharge is applied. S/At Since At is fixed, the number of increments n is dependent on the values 137 of cv and t3. For the sludge landfill with cv = 0.063 inZ/min, n was equal to 113. The percent consolidation, defined as H U(t) = 1 -% X15552 (6.14) 0 o where u(t) is the excess pore pressure at any time t and uo is the initial excess pore pressure, has been evaluated numerically, using the trapezoidal rule, for the finite difference formulation described. For the linearly increasing load, uo at any time t is equal to the total number of increments of pore pressure applied up to time t (u = n at t = ts). To obtain the settlement at time t it is necessary to determine the load acting on the lower layer at that time. The settlement of the lower layer then equals the ultimate settlement for that load multiplied by the percent consolidation based on the above consolidation theory. Estimates of the ultimate settlement ’of the lower sludge layer for three different elevations of the upper sludge layer (different loads) are given in Figure 6.14 for use in obtaining the theoretical time-settlement curve. In the lower sludge layer it was assumed that the pore pressures measured in the field after application of the middle sand blanket acted as "static” pore pressures for analysis purposes. This means that they have been considered as both the initial and the residual pressures, and they must be added to the excess pressures calculated from the above theory to obtain the actual pore pressures. Since the actual residual pore pressures are slightly different from the above assumed values, the consolidation percentages calculated by 138 the theory contain a small error. Gibson's (1958) theory would provide accurate values of pore pressures generated in the sludge due to its own weight if estimates of initial pore pressures were needed for design purposes. Using a computer program written for the above analysis (Appendix G), two theoretical time-settlement relations for the lower sludge layer have been determined and are shown in Figure 6.15a, along with the actual field settlement curve for group 3. The two theoretical curves occur after surcharge placement, one being calculated using cV equal to 0.063 inZ/min and the other with cv equal to 0.015 inz/min. A cv equal to 0.063 inz/min was assumed during the linear loading range and was chosen based on the analysis of the upper sludge layer. Values of tp equal to 26 days and Ca equal to 0.0556 (from the upper layer analysis) were used in calculating the secondary compression. The ultimate primary settlements used in the analysis are those shown in Figures 6.12 and 6.14. The three analyses shown in Figure 6.14 were used during linear loading and the 32.6 inches in Figure 6.12 was used after surcharge application. The computer program assumes an average thickness for the sludge layer for the computations during linear loading and adjusts the thickness after each settlement computation after surcharge application. I The theoretical procedure above appears to give an adequate time—settlement relation for the lower layer. Although the occurrence of secondary compression has been poorly modeled, the governing factor affecting the time-settlement relation still appears to be the selection of a representative value of cv. The fact that the actual settlement curve falls above the curve for cv equal to 0.063 inZ/min would indicate 139 that cv has decreased during the settlement process. This would be in accordance with the laboratory data, which show a drop in cv with an increase in deformation and effective stress (Figure 5.2). Leonards (1962) describes a simple procedure, suggested by Terzaghi, for obtaining the time-settlement relation of a clay layer subjected to a constant rate of loading. Using this procedure, the theoretical curve shown in Figure 6.15b has been drawn and is seen to agree very well with the field curve and the previous theoretical solution of Figure 6.15a. The solution was obtained by using the Terzaghi procedure in the linear loading range and then combining it with the solution for an instantaneous loading after the application of the surcharge. 6.3.2.4 Pore Pressure Dissipation.--A comparison between the predicted and measured pore pressures at the mid-point of the lower sludge layer is shown in Figure 6.16. The initial pore pressure was assumed equal to the residual value of 2.3 psi and was added to the excess pore pressures generated during loading. Pore pressures generated during the linear loading period were estimated using a value of cv equal to 0.063 inz/min. This estimation appears to give a reasonable approximation to the measured pore pressures. Two predicted curves are shown after surcharge application, one representing a cv equal to 0.063 in2/min and the other a cv equal to 0.015 in2/min. The larger cv value predicts pore pressure dissipation more rapidly than it occurs. This again suggests that cv has decreased for the lower layer as a result of its consolidation under the linearly increasing load. The measured pore pressures fall between the two theoretical curves for 140 a period of 30 days after surcharge placement, after which they dissipate more slowly. This would correlate with the decrease in the rate of pore pressure dissipation which occurred after 70 percent dissipation in the upper sludge layer (Figure 6.9). Initial pore pressures generated in the lower sludge layer due to its own weight are shown in Figure 6.17, and residual pore pressures remaining after consolidation are shown in Figure 6.5. The initial pore pressures were obtained by subtracting 100 psf (stress due to the middle sand blanket) from the pore pressure readings taken immediately after placement of the middle sand blanket. These pore pressures agree fairly well with those that would be predicted using Gibson's (1958) theory. Residual pore pressures shown in Figure 6.5 were obtained in a manner similar to the upper sludge layer. After 327' days (Figure 5.12) the pore pressures had stabilized sufficiently so that they could be labeled "residual" for analysis purposes. The values are somewhat higher than those measured in the upper sludge layer, indicating that a higher threshold gradient exists in the lower layer. The higher sludge density of the lower sludge layer in combi— nation with any gas formation due to sludge decomposition may have contributed to the formation of the higher residual pore pressures. Using the maximum observed residual pore pressure at the mid-point of the lower layer gives a value of 10 equal to 1.63. The Au/Ap ratios shown in Figure 6.7 are somewhat less for the lower sludge layer as compared to the upper layer. The lower ratios may be the result of partial drainage having occurred during placement of the upper sand blanket and surcharge. A shorter length of drainage 141 path existed in the lower layer than the upper layer at the time of surcharge application. The theoretical pore pressure increase shown in Figure 6.16 is consistent with the field measurements and would support this explanation. Because the surcharge covers a fairly large area it would appear that the reduction in the Au/Ap ratio is not due to reduced stresses in the lower sludge layer. Table 6.1 COMPARISON OF ACTUAL AND CALCULATED PRIMARY SETTLEMENTS. Location Computed settlement Actual field from Figure 6.3 or 6.12 settlement Upper sludge layer Upper half 10.8 in 9.0 in Lower half 7 3 in 8.0 in Lower sludge layer Upper half 19.6 in 14.7 in Lower half 13.2 in 14.3 in 142 .Aanma .mnmg cam pcmamuopsuso samuumnlwmouum Hmowmss .H.o musmfim N am .sfimuum Hmax< om «N NN ON ma 0H «a NH OH w o c N o _ _ a _ l _ _ J. _ _ _ _ _ o o. S o 3 _ H a o w o D. to . m m o o a Nao\wx w.~ n m. o c acousoo ofismwuo qu 0\\\AV\\LU n. q pm; _ D— I; m cflx NEu\wx m u m. %M w a. Ii 0 M, osmusoo ofiam Ho mom m7u la n 143 .mo>uso uCoEmHuummuuoEwu msu Gouw pmumflsoamo mums 30am msu paw mums 30am mumsommfi panammoe mnu ammzumc comwumano U CHE\muw .wumu Son pmumasoamo . o N.H o.H m. o. d. N. o _ a _ _ — _ :ZRH HN\NN\HH O O :\NH\: I an}: .3 O momma \\\\\\v \ Hm\ma\.: O .N.s magmas «.0 q.o 0.0 w.o o.H N.H urm/ 3; ‘9391 MOI; painseem ‘mb ' S I, [I :‘n' IOU psi ,{1 ’ 7W 'L/fl3 V ' . . 4m /! ‘ 140 ) (. i ’g C '3; . ., ' 332 4-“5 w = 257.34 (av .) /... g “if; sand 800 1 15 3 o 55 - = ' 0 U1 (IO 60 (a) +L1 surcharge, Ap = 390 psf 1,7 sand 390 100 psf 490 4 / 390 ‘27s 15 ‘ 550 Fiji) 7) / 390/ 450 00 f 640 4 S x V V 390 625 285 730 A La sand 390 800 210 7 980 A0 + o - = o' Ur f m (b) 7 18.34 /v 16.90 0!) :2 F / ..= C. 10g ("E/”(3) U) ’ ° 19.40 1+CO 10 g 12. 8 4 fifij 3.46 (C) I Figure 6.3. Estimated effective stress changes and strain distribution in the upper sludge layer. (3) Initial stresses. (b) Final stresses. (c) Strain distribution. 145 Sludge U-4-3 J[ o = 3.4 psi ’ ho = 0.7500 in 3.0 ”_ 2 2 a = 5.01 x 10" in /1b b = 4.72 x 10‘3 inZ/lb r4 2 5 l/l = 6.95 X 104 lb/inZ/min \T . k3 r-~l x a ‘H . 2.0 v—i I N ((3 T” 1.5 53 d) o ,4 1'0 t = 150 min a I... 05 I J I I J 0 100 200 300 400 500 Time t1, min Figure 6.4. ‘Parameter determination for the method of Gibson and Lo. .Loamn momum> madmmmua muoa mmmoxm Hmapwmmu pounmmmz .m.m ouswwm Eouw pmchuco coflomoofi umuoEonmfia some now mmoam> mwmuw>m mum wmwSH "muoz IMO mma .oMSmmmsa a whoa mmmoxw Hmspflmmm . s _ b. H l _ 00w COO 00¢ oom owa 00H Odfi ONH OOH ow oc oq om ‘qndaa saqou; .m.o enemas Nm\m\w "sumo comm mema mwpsHm umBOH comm momma mwpsam Home: comm k, 1 2 C ‘2'; v . f \\Rfipm \\\; 2? v: o 2‘ I- n I D 0" u )1» ’J ,I I, \\\\\ “PMS \\\ a"! /" I. r ._*k .meflu msmpm> usoEmHuuom .%uoo£u HmeNHmH Amv .Hmmma mwmslm Home: .mm>uso ucmEoHuummunoEHu wouowpmua cam Hmsuom mo comHHmQEoo .o.o muswwm ommo.on do .swe\msw omoo.on>o mnmumEmHma pfimwm .zuomsu “Swmuumfi NV .0 .ocmEoHuuom mumefloas mcmHummomz .omao.ou o .cHE\ aw OmHo.ouoo mumumEmuma an .hpomsu Hawmuufiw AV 2 N Hmhma mwpsHm Home: 0 osouu .usoEoHuumm pHmfim nu a msme «m u. o . 0C m>HDU 7 I4. ‘1 mmmp .meH .«9 Pl; w. _ _ _ r _ w _ omm osN OHN. ems ems oNH cs H as on woman ucoEmHuuwm m maesam moxsmag pcmm .s I\\\\\\\{ I R\\ El] mwumnousm Hwom on em 0H IL/OI/G O OH ON ‘Juawatnqog soqou; '33 ‘oseq onoqe onnIS JO UOIJBABIQ 148 .oEHu mo Enuflumon msmum> uswEoHuumm .%Hom£u stmnumH Anv .umhma ompsHm some: .mm>H:o osmEmHuummunmEHu pmuowvmua new Hmsuom mo comwumasoo .c.o muswwm mnsos .mefiH ooooH oooH ooH om jj_fi__ _ _Zfll___ a _______ ’ I1 0N II ma 5 . > . ammo. u u cas\mcm omoo. n o osmEmHuumm pfiowm pmuofiponm Hfiwmuuofi nv unwEmHuumm macaw o asouu AV II 0H momma owpsam Home: .I m .1 o soqou; ‘quomQIJJaS 149 .meHu mo snuwumwoa .m> usmsmHuumm .04 was somnww mo auoopa mmpsam Home: .mm>uso unoEmHuummIImefiu pmuoavmun was amouom mo somHquEou mason .msHH on .ummma ooa swE\NaH osmo. GHE\NSH omoo. cwe\mcw Onao. > o .ucmeHuumm pmuofiumum >o .uaoanuumm pmuowpoum >0 .usmEoHuumm wouoflpmum 0 among .usmEmauuom mama» OD _— _ _ _ A _ .s.s museum on 3 l 8 l 3 I. 3 II n i c ‘nuamatnnas saqour 150 .mefiu wo azuwumwoa .m> ucmEmHuumm .kuomnu m.manm3 Avv .umuma mmvsam some: .mm>usu unmsoauummIImEHu umuoavmum can Hmsuom mo consumaaou .o.o madman muso: .mea 83 2: om. _ A A _ A _ — A A A A1.a A _ a _A _IA A A A Il.o~ GilfllI I?! nrlil .I.mH Ilioa a quO. u >0 //D/ afle\ cw omoo. u o .ucmEmHuumm wmuofivmum AV . ll; N e/ la s //01 mqao. u >0 cfla\acfl mmao. u o .ucmEoHuuom pmuoavmum AU [Au 6 o msouo .ucmsmauumm vamwm nu Ilo ‘auamataaas saqou; 151 HmBOH .m asouo on Anv fl ON A 0 ma _ \x .m _. u. _A s A“ 0A . _ A a. _ -I «A m _ / r A _ A A b o.H w. o. a. N. NH AAA OH A f \\\\ .lm .W _\R m _ A II o . T: 5» 5 _ ox IIlV 3 l / _ / _ .l N . A A _ A _ r o A w a s N Hma «.mu as .ummmA noBoH .5 com o masouo Apv .uohmA Home: .m asouu Amv comm comm comm comm mwumLUHSm .Hozma Home: .5 com o mosouu Apv .mwpmzopsm pom umxcman bcmm some: ecu wo :oAumoHHaam ecu ou mop wwmouoCH snowmoum muom .ummmA A%\\\\GEP“TS X\ fl I I. ‘W 1 l 531 .zzl\\\X\\ .3... I . \\\\\Ial .A.s .tsmAt Adv _ om \.\\I _ my .. wA _ . . _ A. I. sA _ A . _ a I s _ ,, _ _ _ _I _ _ o.A w. s. s. N. NA Amv _ I... OH _ \\\I I. _ II .. w _ .Cd. _A I. 0 _Or/ . I I s _ / /nr _ II/ II N _ I _ ._ _ _ _ _ o 199; ‘qndaa »naa; ‘qqdaq 152 .Hmmma mwpsam Home: musmmmna muoa bosommme Amwuficfl > CHEANcA smso.o u o sAmAA > CHE\NCA okAo.o I u smA >o\o e N Ame .ousmmmua muoa Amflowcfi ..5 A oos n o.-.< H _ cos mo m3m> mmmum>< O .muomsu m.¢0m£wu RV .xuomsu m.c0m£Ho AV ONH OOH ow om oq ,om .mmuommmna mnoa Amwuw:w pmuofivoua ‘qndaa saqour paw monommme mo COmAumano mama em cae\ca m-oA x A~.m u sme\uu mmm.o .w.a .stut pawn I" ’ 0‘ v! V ='fl ? ‘f. ’9' .71 ’ \\\\\Y’3P“ I S \\\\ .zuoozu m_wzwmmumw Amv .uoxmA owpsam Amado mo Aswoapfle .mausmmmwm whoa pwoowpmua cam cousmmme mo cemwumano > .a.s .rswAA .cAENcA 88.0 I 0 33A .385... Emmfims D .CAE\NCA oNAo.o n >o cmA .xuomcu stmuuoe Afl .o moouo .m Acumeommfla .ouommoua muom pAoAm nu 4. .0 A“ .oc o>uso IIIIV N xv 4 fl 6 Q A a\ « o a o o a m I I AW mzmp .mEHH A A A A A A A oAN owA OmH ONH om “V300 om umumEoumwm .+ \\\ “w\ mwAuAAHm \\u \ umxcmAn pcmm mmumsounm AAom [] (Z) /. Eféiftibxc+ N IL/OI/6 O ._4 O N Isd ‘alnssald alOJ '3; ‘aseq aAoqe aBpnIS go UOIJBABIQ 154 .04 was somnfiu mo xuomne Anv .ummma wwwsam some: «0 ucfioaIvfle .mmusmmmua muoa pmuoflvmua cam Hmsuom mo somfiumaaoo .m.o madman > . o .oA cam somnwo mo known» .musmmoua muoa wouowvmum. AV GHE\NCH oNoo. > :H5\Nsw okao. u .04 van somnfio no anomzu .musmmmua muoa vmuowpwum HA umxma ownsam Amman mo usfloalvws .o msouo .musmmmua anon uamfim .nv mzmp .oeHH d rsd ‘aznssaxd 910 0mm oqN OHN owH omH ONH cm Co on umumEoumHm + mmesAm umxsman psmm \\ +\\\ \N—\\\ EU mwumnousm Hwom / O N '3; ‘aseqsaAoqe aBpnIs go uornenatg 155 u «F—— u 0 O 0 Fur % A \ ”11 9§———-— \—, ioyH/Z 1 Figure 6.10. Theoretical final pore pressure distribution at the end of consolidation if a threshold gradient exists. sand 2‘: 0 200 400 600 800 % , I . I . I . I w u pore pressure, psf 20 0 ///// -§ >Chx Ci \ w—I \ m 40'_’ - ‘\ OD “ I a 5 AR m 5:” f 8. _ a // __ sand f§§§§ 100 120 ‘ Residual pore pressure (3 [3 Initial pore pressure [3 ‘Maximum pore pressure Figure 6.11. Comparison of initial, maximum, and residual pore pressures for the upper sludge layer. 156 ”—7 sand, I = 100 pcf 100 psf 100 psf 7 ~ N 5.10 :jj 'y : 70 pcf m 275 244 31 5-50 ,0 c = 1.65 '0 C :3 q A. E w = 265.17. (avg.)/ 450 317 133 4'85 % B0 = 9‘5' / 625 ‘ 360 265 4'35 as sand 800 0 800 3 ° 55 O - ui = ()0 CO (8) V/ % {4 sand ‘_ 1290 psf 100 200 1190 psf [ 1290 /‘275 ' 400 / 1165 Z‘ 1290 /‘450 7 330 " Z 1410 Z ’ 1290 / 625 27 / 1640 x ‘ T; \<>Q>\gsludg€\§<::83g’ 1290 800 o 2090 A0 + o - Ur = 0% V (b) A ‘23 sand 29.1% /é; 40.0 Cc ,/ , = —--—-—- O G 'g E 7 e 1 + e 10g10 ( f 0) r-I ’ ° 0 m 28.9 ;§: 24.4 If '3 sand '15.1 (e) Figure 6.12. Estimated effective stress changes and strain distribution in the lower sludge layer. (8) Initial stresses. (b) Final stresses. (c) Strain distribution. .1. surcharge placement ‘7?" __.__ __._.__ __ ‘H m E?“ | .Az”' n = no. of steps to model 0 on P I . ”.3 r—— I linear load. §'$ I I = 113 for sludge analysis 6 H u o m m I m o.>. vs o.m . o.s.4 ‘ 1 1.0 I I... .. A. . Figure 6.13. s Time Load increasing linearly with time followed by an instantaneous surcharge application. 158 .umxma omwnam moan: msu mo msoAum>mHm usmumwmfiw pom umNmH mwwsam umSoH can «0 unmamHuumm mumEHuHs mo moumEAumm .qa.o muswfim .ommo some now usmummmwp ma o< umnu unmoxo NH.o muswfim sfi szonm mm ousvmuoum seam mnu BoHHom mum: saonm mmmhaoam one "ouoz :¢.®N fl UEG N 6 =m.o~ I use mg: AWN Assam N m ..m.mA I AAAAA m.mH . \ x o w _ 2 IA“: Aosmm N o \ m MN m. w.m.n N 5m w Aug—mm . P S / a mm W _o.A 3: m .2 \ . . m \ Nam A“ s AAA S Q II \ . A I \ . w \ \ H wH A” 7 I -- A. D. \\\ pawn 00 b ”I I \\Q x .mé \ . \ \ .m Ufimm AMVKI. AP. \\ [Al 1 __fi 159 .COflunacw mucmummmww qucfim Amy lllllnl-"IIUI'II _UIIII mYI. xr|r I! Ill/IAN/ .HF mmmv / Do u a ammo. - do 1 cowumUHHaam mwumsuusm “mumm awe\mcw mac. n >0 .ucmEmHuumm cmumasuamo AV 5 ommo. n >0 cfiE\NcH moo. .ummma wwwsam umzoa mo mmmw .mEHH u .ucmEmauumm wmumasoamu mu .m asouu ucmEmHuumm 30: G .umzma wwwsam pmxoa .mm>usu uameHuummllmEfiu nu.wmusmmma vcm vmuuwwmum msu :mm3umn comfiumano .mH.o muswfim I :nT I I u vmesmmm ,_ . _ own; ,oqw OHN owa omH QNA mumaa ucwEmHuumm mwusam umxcman vcmm mwumzousm Hwom [J EB E O¢ ‘ \\\\l I [\\\\\VI / Eahlk\\ om om H O IL/OT/6 O r-l O N ‘nuamatnnas saqau; '3; ‘aseq BAqu afipnts go UOIQBABIQ .nmoa wcwmmmuucfl maummcwa m How musvmuoun finmmuume um3oa .mo>uso uamsmauwmmnnmawu wmusmmms wan vmuUvaua mnu ammzumn somfiquEOU Anv .ummma mwvaam .mH.o munmfim nwl, IlAvur In a..|.naunn....;u: .. mWN .II on a E u vaSmmm . ’ J , 1 a d y ommo. u o > I GHE\N:H omoo. u o .vmoa wcwmmmuoafi xaummawa AU m How muswmooua HawmuumH .uamEmHuumm vmumaaoamu AU /. .m asouo .um%ma wwwsam um3oa m5» m0 unmamauumm wawwm nu /., I1 m%mv .mEHH . _ _ _ _ _ .I _ QanN. fiqm OHN owa omH ONH co oo o mumaa ucmEmHuumm II. AMN Wu“ .n .I.OH mwuflm Vs “ 3x53 23 U m 1 mwumnuunm 30m a m Ilom .3; ‘aseq anoqe aSpnIS go UOIJBABIH ‘nuam313333 saqau; £61 sowumUHHaam mwumcuusm .umwmfi mvaHm umsoa msu mo ucHOQUfiE mcu um mmusmmmpa mpoa vaSmmmE wan vmuofiwmum cmm3umn comfiumanu .oa.o musMHm J Izpwm sflfi New mac. n >0 .munmmmua muoa vmuoflwmum AV > l4 o cflfi\mcw moo. u o .musmmmua muom wmuuwwmum _U .o amouo .umxma I umzoa mo uafloawfle .muammmua upon UHmHm AU 11 q In N u a .flmm om.m u munmmmua muoa :owumum: u s u a mesmmm mmsam> vmuowvmum Wm Lm mkmw .939 4U T I w_ _ h _ _ L _ _ 0 0mm oqm OHN cmH OmH ONH 00 oo om m l umumEoumHm + k IL “VI OH mmcsam mu “mfi \ I umxcman vcmm D X mwumnousm Hwom mm RUM I1 om 13d ‘alnssald 310d '3; ‘aseq aAoqe eBpnIs go uoxnenatg 162 .um%ma wwwsam umsoa mcu CH mmudmmmum muoa mmmuxm Hmwuflcfl vmumeflumm wsm wmusmmmz .ma.o musmwm afle \NOH OO0.0 n >0 .zuomcu m.comnwo Eoum mmusmmmum muoa wmuuwvmum nu mmuSmmmua whoa vmusmmme .w>< AU IJOQH > ONH . ”w? ficmw 3.0 u 03 E G W N OOH .w .\\ n .\\ m. \\ OO 1. u s m m. co m %w umzmfl a mwvsam on “ umsoa I x x _ b _ _ b L [K ooc ooq com o mmm .munmmmua muom CHAPTER VII SUMMARY AND CONCLUSIONS 7.1 Field Consolidation An experimental papermill sludge landfill was constructed and monitored to obtain engineering information essential to developing guidelines and recommendations for the design and operation of solid papermill waste landfills. The landfill consisted of 2 sludge layers, initially 10 ft. thick, with sand drainage blankets at the top, middle, and bottom. An earth dike provided lateral confinement fOr the soft sludge during and after construction, and 3 ft. of natural soil provided the surface load. The landfill was instrumented with 32 settlement plates, 16 piezometers, 3 total pressure cells, and 10 thermistors. Field data were obtained, during the year, on settlement, pore water pressures, vertical and lateral earth pressures, temperature, sludge unit weights, specific gravity, and water contents. Laboratory work included consistency limits, ash contents, and consolidation tests on both fresh and undisturbed samples of sludge. Comparisons have been made between field settlement behavior and predicted behavior using laboratory Esst parameters, backfigured field parameters, and soil mechanics theories, including those on consolidation and pore pressure dissipation. Conclusions are given under the following headings: (l) settlement, (2) pore pressures, and (3) stress and temperature conditions. 163 164 7.1.1 Settlement l. Reasonable estimates of ultimate primary settlement for the sludge can be obtained using equation 6.2, provided that both the initial and residual pore pressures are used in computing effective stresses. A laboratory value for the compression index Cc appears to be appropriate, and the initial void ratioveo for the field sludge layer may be taken from a laboratory void ratio-logarithm of pressure E curve at the appropriate stress level. 2. MacFarlane's (1969) method, using data from a single A"! I increment laboratory consolidation test, overestimates primary mhll‘h .. f. settlement. Results for this method gave estimates of primary. ? settlement that were closer to the actual total settlement of each sludge layer. This may be due to the high initial void ratio of the laboratory~samples. 3.r Gibson and Lo's (1961) theory provides an accurate estimate of total settlement and time-rate of settlement under instantaneous loading conditions. The time-settlement relation is dependent on the assumed value of cv and predicts that the ultimate settlement is reached without the development of a linear (with log time) secondary compression curve. Careful laboratory tests were required to determine the parameters a, b, and A used in this theory. 4. The field settlement versus logarithm of time curves shown in Figures 5.10 and 5.11 exhibit a decreasing secondary compression rate with log time. This behavior was observed for both the upper and . lower sludge layers although it was not experienced with any of the samples tested in the laboratory. 165 5. Estimates of secondary compression, based on equation 6.5 and Wahls's (1962) theory, are too low for laboratory values of the coefficient of secondary compression, Ca' Backfigured field parameters yielded apprOpriate estimates for the upper sludge layer, while a somewhat arbitrary value of tp had to be assumed for the lower sludge layer. 6. Terzaghi's (1943) theory and Wahls's (1962) theory appear to adequately predict the hydrodynamic portion of the time-settlement relation for the sludge, provided that an appropriate value for the coefficient of consolidation, cv, is used in each theory. Satisfactory results were obtained for both the upper and lower sludge layers for the different conditions of loading. The coefficient of consolidation appears to decrease with an increase in field consolidation similar to the decrease shown by laboratory tests. Environmental factors (surface drying, etc.) influenced the time-settlement relation for the upper sludge layer in the landfill. 7. Settlement rates for the landfill gave a good estimate of the flow rate for leachate draining from the papermill sludge. 8. Undisturbed samples taken from the landfill yielded valuable information concerning the sludge's laboratory e vs. log 3 relationship and the variation, with effective stress, in the coefficient of consolidation, cv, primary compression ratio, r, and the coefficient of secondary compression, Ca’ that occurred with field consolidation followed by sampling and laboratory testing. 7.1.2 Pore Pressures l. Gibson's (1958) theory gives estimates of pore pressures 166 generated during sludge placement that are in accordance with field observations. Pore pressures in the sludge were influenced by excess pore pressures that built up in the middle sand drainage blanket. These were the result of incomplete drainage and were caused by greater settlement occurring in the central portion of the landfill. 2. Terzaghi's (1943) theory and Gibson and Lo's (1961) theory accurately predicted pore pressures in the upper sludge layer up to about 70 percent dissipation, provided that an appropriate value for the coefficient of consolidation was used. It was also possible to predict pore pressures for the lower sludge layer, which experienced different conditions of loading. After 70 percent dissipation, the pore pressures decreased at a slower rate and eventually appeared to stabilize at some residual value. This indicates that a threshold, gradient exists for the sludge in the landfill, below which little or no flow of pore water can occur. Pore pressures may also be influenced by environmental factors, as demonstrated by the pore pressure fluctu- ations of the upper sludge layer with time. 3. The assumption of a uniform initial excess pore pressure for use with Terzaghi's theory appears to be reasonable because of the closeness in magnitude between the initial pore pressures generated during sludge placement and the residual pore pressures. 7.1.3 Stress and Temperature Conditions 1.. The undrained shear strength of the sludge increased considerably during consolidation and is greatest at points in the landfill that are under the highest effective stresses. A linear relationship between undrained strength and consolidation pressure 167 was indicated by the data shown in Figure 5.7. Sensitivity of the sludge in terms of the ratio of undisturbed to remolded vane strength was less than two. 2. The vertical stress measured close to the mid-depth of the lower sludge layer by the total pressure cells was in fair agreement with the stress calculated on the basis of material unit weights, indicating that the measured lateral stresses should be equally accurate. 3. The coefficient of lateral stress, KO, based on total stress and pore pressure data, decreased from about 0.65 immediately after sludge placement to about 0.32 for the final stage of consoli- dation. 4. Temperature increase due to increased biological activity peaked about 50 days after completion of the landfill giving a maximum temperature rise close to 7°C in the upper half of the lower sludge layer. Thereafter sludge temperatures were determined by ground and seasonal air temperatures. REFERENCES 168 REFERENCES American Society for Testing and Materials, Book of ASTM Standards, Parts 11 and 15, Philadelphia, Pennsylvania. Andersland, O. B., and Laza, Robert W., "Permeability of High Ash Papermill Sludge," Journal of the Sanitary Engineering Division, Proc. ASCE, Vol. 98, No. SA 6, December, 1972. Andersland, O. B., and Laza, Robert W., "Shear Strength and Permeability of High Ash Pulp and Papermill Sludges," Tech. Rpt. l for the National Council of the Paper Industry for Air and Stream Improvement, Inc., Div. of Engineering Research, Mich. State Univ., E. Lansing, Mich., 1971. Andersland, O. B., and Paloorthekkathil, John M., "Consolidation Behavior of High Ash Pulp and Papermill Sludges," Tech. Rpt. 2 for the National Council of the Paper Industry for Air and Stream Improvement, Inc., Div. of Engineering Research, Mich. State Univ., E. Lansing, Mich., 1972. BishOp, Alan w., and Henkel, D. J., The Measurement of Soil Properties in the Triaxial Test, Edward Arnold (Publishers) Ltd., London, 1962. Bjerrum, Laurits, "Engineering Geology of Norwegian Normally- Consolidated Marine Clays as Related to Settlements of Buildings," Geotechnique, London, 17:8l—ll8, 1967. Bjerrum, Laurits, "Embankments on Soft Ground,” Proc., Specialty Conf. on Performance of Earth and Earth-supported Structures, Am. Soc. of Civil Engrs., Il:l-54, June, 1972. Black, C. 8., ed., Methods of Soil Analysis, No. 9 in the series Agronomy, Am. Soc. Agronomy, Inc.. Part 2, 1965. Casagrande, A., "The Determination of the Preconsolidation Load and Its Practical Significance," Proceedings, 1st International Conference on Soil Mechanics and Foundation Engineering, Cambridge, 3:60, 1936. Davis, E. H., and Raymond, G. P., "A Non-linear Theory of Consoli- dation,” Geotechnique, London, 15:161-173, 1965. Follett, Robert, and Gehm, Harry W., "Manual of Practice for Sludge Handling in the Pulp and Paper Industry," National Council of the Paper Industry for Air and Stream Improvement, Inc., Tech. Bull. No. 190, June, 1966. 169 170 Garlanger, John E., "The Consolidation of Soils Exhibiting Creep Under Constant Effective Stress, "Geotechnique, London, 22:71-78, 1972. Gibson, R. E., "The Progress of Consolidation in a Clay Layer Increasing in Thickness with Time," Geotechnique, London, 8:171- 182, 1958. Gibson, R. E., and Lo, K. Y., "A Theory of Consolidation for Soils Exhibiting Secondary Compression," Norwegian Geotechnical Institute, Publication 41, Oslo, Norway, 1961. Gibson, R. E., England, G. L., and Hussey, M. J. L., "The Theory of One-dimensional Consolidation of Saturated Clays," Geotechnique, London, 17:261—273, 1967. Gillespie, W. J., "Summary Report--Questionnaire Survey--Sludge Cake Disposal on Land," National Council of the Paper Industry for Air and Stream Improvement, Inc., Unpublished, September 1969. Gillespie, W. J., Gellman, I., Janes, R. L., "Utilization of High Ash Papermill Waste Solids," Proc. 2nd Mineral Waste Utilization Symposium, IITRI, Chicago, I11., 1970. Gillespie, W. J., Mazzola, C. A., and Gellman, 1., "Landfill Disposal of Papermill Waste Solids," presented at the 7th TAPPI Air and Water Conference., Minneapolis, Minn., June 7-10, 1970. Grim, R. E., Clay Mineralogy, McGraw-Hill Book Co., Inc., New York, 1968. Grim, R. E., Applied Clay Mineralogy, McGraw—Hill Book Co., Inc., New York, 1962. Harr, M. E., Foundations of Theoretical Soil Mechanics, McGraw-Hill Book Co., In., New York, 1966. Janbu, N., "Consolidation of Clay Layers Based on Non-linear Stress— strain," Proc. 6th Internat. Conf. on Soil Mech. and Found. Eng., II:83-87, 1965. Lambe, T. William, Soil Testing for Engineers, John Wiley and Sons, Inc., New York, 1951. Lambe, T. William, and Whitman, Robert V., Soil Mechanics, John Wiley and Sons, Inc., New York, 1969. Leonards, G. A., Foundation Engineering, McGraw-Hill Book Co., Inc., New York, 1962. Leonards, G. A., and Ramiah, R. K., "Time Effects in the Consolidation of Clay," STP No. 254, ASTM, 116-130, (1959). a; .195. .1 {fi’,"“-.“ a $14.14 1:4. l7l Leonards, G. A., and Girault, P., "A Study of the One—dimensional Consolidation Test," Proc. 5th International Conf. on Soil Mech., and Found. Engr., Dunod, Paris, 1:213-218, 1961. Lo, K. Y., "Secondary Compression of Clays," Journal of the Soil Mech. and Found. Div., ASCE, 87:SM4:6l-87, 1961. MacFarlane, Ivan E., ed., Muskeg Engineering Handbook, Univ. of Toronto Press, 1969. Mitchell, J. K., and Younger, J. S., "Abnormalities in Hydraulic Flow Through Fine-grained soils," STP No. 417, ASTM, pp. 106-139, 1966. Scott, R. F., Principles of Soil Mechanics, Addison-Wesley Publ. Co., Inc., Reading, Mass., 1963. Terzaghi, Karl, Theoretical Soil Mechanics, John Wiley and Sons, Inc., New York, 1943. Terzaghi, Karl, and Peck, Ralph E., Soil Mechanics in Engineerigg Practice, 2nd ed., John Wiley and Sons, Inc., New York, 1967. Wahls, Harvey E., "Analysis of Primary and Secondary Consolidation," Journ. of the Soil Mech. and Found. Div., ASCE, 88:SM6:207-23l, 1962. APPENDICES 172 173 .36 .H .0: 33a osogofiuom N .o: macaw 0O. whammy HnND "30sz 15.55 O~.O5 HO.55 mO.55 Nw.55 O5.55 vO.O5 5~.O5 N5\H_\O N5.55 O~.O5 No.55 mO.55 m¢.55 15.55 mO.O5 5N.O5 N5\H\O O5.55 IN.O5 OO.55 OO.55 O¢.55 OO.55 ~O.O5 m~.O5 ~5\¢\m "5.55 ¢~.O5 HO.55 IO.55 H¢.55 O5.55 ¢O.O5 O~.O5 ~5\O~\m OO.55 EN.O5 5O.55 NO.55 OO.55 OO.55 HO.O5 m~.O5 N5\v~\~ O5.55 v~.O5 OO.55 IO.55 sv.55 O5.55 mO.O5 m~.O5 ~5\m\~ O5.55 ON.O5 NO.55 5O.55 m¢.55 N5.55 mO.O5 O~.O5 ~5\«H\~ 55.55 ON.O5 ~O.55 OO.55 av.55 _5.55 mO.O5 O~.O5 ~5\Om\- ~5.55 ON.O5 EO.55 mO.55 N¢.55 H5.55 wO.O5 5~.O5 H5\ml\~_ m5.55 ON.O5 MO.55 mO.55 mv.55 O5.55 IO.O5 O~.O5 a5\O\~_ v5.55 O~.O5 OO.55 5O.55 ww.55 15.55 «O.O5 5N.O5 H5\H\~H m5.55 ON.O5 MO.55 mO.55 Nv.55 O5 55 OO.O5 O~.O5 H5\NN\- m5.55 m~.O5 MO.55 5O.55 ~¢.55 H5.55 mO.O5 5~.O5 HO\OH\HH‘ O5.55 O~.O5 IO.55 5O.55 m¢.55 m5.55 ¢O.O5 Om.O5 a5\ml\aa 55.55 m~.O5 mO.55 5O.55 ¢¢.55 O5.55 MO.O5 5N.O5 H5\~H\~a m5.55 O~.O5 mO.55 O5.55 m¢.55 O5.55 5O.O5 ON.O5 H5\OH\- $5.55 5~.O5 5O.55 55.55 N¢.55 OO.55 OO.O5 Hm.O5 H5\O\HH v5.55 O~.O5 5O.55 OO.55 ¢¢.55 O5.55 5O.O5 Om.O5 H5\m\al O5.55 5~.O5 OO.55 O5.55 m¢.55 O5.55 5O.O5 5N.O5 ~5\N\~H m5.55 Hm.O5 OO.55 O5.55 m¢.55 OO.55 HH.O5 Hm.O5 H5\ON\O_ 55.55 NO.O5 OO.O5 O5.55 5¢.55 HO.55 OH.O5 mm.O5 H5\N~\O~ O5.55 NO.O5 OO.55 v5.55 O¢.55 OO.55 OE.O5 Om.O5 H5\O~\Oa O5.55 Om.O5 OO.55 O5.55 m¢.55 O5.55 OO.O5 am.w5 H5\¢H\OH M5.55 Hm.O5 OO.55 O5.55 Oe.55 O5.55 OO.O5 Hm.O5 s5\O\OH m5.55 Hm.O5 OO.O5 O5.55 O¢.55 O5.55 OO.O5 lm.O5 H5\O\Oa OO.O5 Om.O5 ON.O5 OO.O5 O5 55 OO.O5 OO.O5 Om.O5 H5\O~\O 33 Two H -50 Too :5 Two . 7.50 .2 -No a -5 mafia .Hrm .ZOHB<>HAM HHMij QzMJH MH<1Hnm HZHEHAHHHm Hu< Mdm<8 174 HO.OO ¢~.OO ON.OO O0.00 OO.HO Hm.HO NO.SO N5\HH\O .3 .OO 2 .OO Om .OO Rwanda Ow .OO OO .8 mm .3 O... .3 55>} OO.OO ¢N.OO mm.OO O5.5O O0.00 OO.HO mm._O mm.HO ~5\O\m OO.OO Om.OO H¢.OO EO.5O 5O.OO NO.HO 5m.HO Om.HO ~5\O~\m OO.OO mm.OO OI.OO NO.5O OO.OO HO.HO Om.HO 5m.HO ~5\¢~\N OH.OO mv.OO Om.OO 5O.5O mO.OO mO.HO Om.HO av.aO ~5\m\~ ON.OO Om.OO m0.00 OO.5O NO.HO OO.NO mO._O O¢.HO ~5\¢H\a Om.OO 5O.OO m5.OO O0.00 NO.HO HO NO 50._O Om._O H5\Om\~a mm.OO O0.00 HO.OO -.OO 5O.~O OO.NO O5.5O mm.aw ~5\ml\- O5.OO mO.HO OO.~O mm.OO wH.HO na.~w O5.HO OO.~O H5\O\NH NO OO OH.HO EN._O vv.OO OE.HO OH.~O «O.SO OO.~O H5\H\NH 5~.HO am.HO Om._O OO.OO mm.HO. ON.NO NO.HO O5.HO H5\N~\~l ~¢.HO m5.HO O5.HO NO.OO mm.HO Om.NO OO.~O 55.HO H5\OH\HH OO.HO NO.~O NO.~O O0.00 5m.HO 5m.NO mO.~O NO.HO H5\ml\al NO.NO NO.NO Om.~O ON.OO Ov.HO OI.NO ¢~.~O 1O.HO H5\~H\HH ~¢.NO a5.~O ~O.~O 5m.OO 5m.HO ¢O.NO ¢N.~O OO.HO ~5\O~\Ha Om.~O OO.~O EO.~O m0.00 OO.HO OO.NO O~.~O mO.NO H5\O\~H NO.NO OH.mO NH.mO m0.00 OO.HO NO.~O Om.~O OH.NO a5\m\aa OO.mO mm.mO Om.MO NO.OO m5.HO O5.~O Ov.~O 5~.~O H5\N\HH HO.OO OO.¢O OO.mO .1111 H5\5~\OH v0.00 OO.HO mO.~O NO.~O mm.~O H5\ON\OH OO.NO ¢O.mO .m5.NO OI.~O H5\-\OH _O.HO MO.NO OO.mO O5.~O O¢.~O H5\ON\OH OH.~O 5N.mm OO.~O 5O.NO H5\OE\OH ON.NO O¢.mw vO.mO HO.NO H5\O\OH 5m.~O Hm.mO m~.mO NO.NO H5\m\OH Ha.mw .1111 mO.mO .111. H5\ON\O NO.mO .1111 Hm.mO H5\5N\O 3mm 15 T3 limo «T50 TOO ~50 TOO 5:3 war/Em .Hh .ZOHH<>MAH mmnm><1m HUQDJm mmmnHD QZ< MHBOA HAZE ho mHZHOnm 10:4 HEB H3. mZOHH<>M1HH HwaaHnH .HZHEMAHHMG N1<.Hdm<.fi 175 O¢.mO 5O.mw OO.mO mO.mO 5O.mw NO.OO mO.mO OO.mO N5\aH\O Hm.mO OO.mO H5.mO 5O.mO OO.mO «m.mO 5O.mO HO.mO ~5\~\O mm.mO O5.mO I5.mO OO.mO H5.mw Om.mw OO.OO OO.mO N5\¢\m Om.mO O5.mO O5.mO ¢5.mO O5.mO O0.00 mO.mO OO.mO ~5\O~\m OO.mO O5.mO OO.mO m5.mO O5.mO mO.mO OO.mO O5.mO N5\«~\~ OO.mO mw.mw 5O.mw ~O.OO mO.mO ~5.mO MO.OO 55.mO ~5\m\~ O5.mO OO.OO 5O.mO O0.00 mO.mO OO.mO NE.OO OO.mO NV\¢H\~ NO.OO 5O.mO «O.OO 5O.mO HO.OO OO.mO OH.OO NO.mO H5 Om\- OO.OO OH.OO OH.OO OO.OO mH.OO OO.mO ON.OO MO.OO H5\mH\NH OO.OO OH.OO ON.OO OH.OO m~.OO -.OO OM.OO vi.OO a5\O\- OH.OO ¢N.OO Om.OO O~.OO mm.OO ON.OO 5¢.OO EN.OO H5\H\NH 5m.OO m¢.OO Om.OO OI.OO NO.OO O¢.OO O0.00 O¢.OO ~5\-\a~ Om.OO mm.OO O0.00 OO.OO O0.00 ¢0.00 O5.OO NO.OO ~5\Oa\aa v0.00 50.00 O0.00 50.00 O5.OO O0.00 NO.OO w0.00 H5\ma\~a IO.OO ¢0.00 eO.5O ¢0.00 5O.OO O0.00 NH.5O O0.00 H5\~H\aa 5O.OO ~O.5O O5.5O O0.00 «H.5O OO.5O mm.5O O0.00 H5\Oa\aa OO.5O Na.5O mm.5O OO.5O O~.5O ma.5O m¢.5O mO.5O H5\O\aa mm.5O O~.5O 5¢.5O Oa.5O mm.5O O5.5O HO.5O Ol.5O a5\m\al m¢.5O Ow.5O MO.5O OO.5O O¢.5O ¢«.5O 55.5O O5.5O H5\~\~H OO.5O 5O.5O OO.OO ~5.5O NO.5O 25.5w O~.OO O5.5O H5\O~\OH OO.5O OO.OO O~.OO wO.5O OH.OO 5H.OO O¢.OO mO.5O ~5\-\O~ OH.OO ml.OO Hm.OO OO.OO ON.OO ON.OO NO.OO OO.5O a5\O~\OH O¢.OO OO.OO NO.OO O¢.OO IO.OO Om.OO mO.OO 5¢.OO H5\¢_\O~ mama Two T50 TOO TOO Two mime Two .75 mafia .Hh .ZOHH<>HAH HMMij QZHAm HHHAH «._.Lq. Mdmmwh B§ZHAH HBjnH HZMEHAHHHm 177 TABLE B-l SPORE WATER PRESSURES FOR THE BOTTOM SAND BLANKET AND LOWER SLUDGE LAYER PORE PRESSURE, PSI PIEZOMETER 65-1 67-1 65-2 65-3 66-3 67-3 65-4 67-4 INITIAL EL.FT 78. 0 78. 5 81.0 83.5 83.6 83.9 83.0 86.4 Date 10/15/71 .10 .30 2.50 2.65 2.00 2.15 1.95 1.65 10/21/71 .05 .45 2.80 2.90 2.90 2.30 2.15 1.70 10/28/71 0.0 .30 3.20 3.50 3.50 3.25 2.70 2.50 11/4/71 .10 .25 3.70 4.40 4.15 3.50 3.30 2.75 11/10/71 0.0 .20 3.80 4.30 4.25 4.20 3.35 3.55 11/12/71 0.0 .50 6.20 6.20 6.70 6.65 5.90 5.80 11/15/71 .10 .30 6.10 6.60 6.90 5.90 5.25 5.55 11/18/71 0.0 .30 5.60 6.60 6.50 5.85 4.90 5.35 11/22/71 0.0 .20 4.80 5.85 5.85 5.45 4.55 4.65 12/1/71 0.0 0.0 3.55 5.00 4.90 4.50 4.65 4.00 12/15/71 0.0 .10 3.35 4.45 4.60 4.25 4.55 4.50 12/30/71 0.0 .20 3.15 3.95 4.20 4.05 4.65 4.10 1/13/72 0.0 0.0 2.85 3.60 3.80 3.70 4.25 3.70 2/3/72 10 0.0 2.60 3.20 3.60 3.50 4.00 3.50 2/24/72 30 0.0 2.40 2.80 3.20 2.90 3.80 3.20 3/20/72 30 0.0 2.10 2.50 2.70 2.50 3.50 3.00 5/4/72 20 .10 2.00 2.40 2.50 2.40 3.50 2.90 8/1/72 30 .30 1.90 2.25 2.30‘ 2.25 3.10 2.40 9/6/72 25 .40 2.00 2.25 2.25 2.25 3.25 2.60 9/11/72 50 .35 2.00 2.30 2.45 2.35 2.15 ‘2.65 178 TABLE B-Z PORE WATER PRESSURES FOR THE MIDDLE SAND BLANKET AND UPPER SLUDGE LAYER PORE PRESSURE, PSI *Drilling rig near here at time of reading. PIEZOMETER 65-5 67-5 65-6 67-6 65-7 66-7 67-7 65-8 . INITIAL EL.FT88. 1 88.3 91. 3 91.4 93. 9 93.8 94. 0 95.5 Date 10/21/71 .30 .20 -- -- -- -- -- -- 10/28/71 .60 .50 -- -- -- -- -- -- 11/4/71 .70 .75 1.20 1.00 -- -- -- -- 11/10/71 .80 1.05 2.10 2.45 1.20 .85 2.35 .95 11/12/71 1.30 1.35 4.60 4.80 4.20 4.00 4.40 2.80 11/15/71 1.10 1.20 3.90 3.95 3.50 3.50 3.75 2.25 11/18/71 1.20 1.25 3.55 3.45 3.10 3.10 3.30 2.00 11/22/71 1.15 1.25 3.00 2.90 2.65 2.65 2.80 1.70 12/1/71 1.00 1.10 2.30 2.10 2.10 2.10 2.10 1.20 12/6/71 -- -- 2.30 2.20 1.95 1.95 2.00 1.15 12/15/71 1.15 1.15 2.80 2.25 1.80 1.80 1.80 1.50 12/30/71 1.05 1.10 2.41 2.30 1.45 1.45 1.50 1.30 1/13/72 1.20 1.10 2.50 2.20 1.50 1.35 1.50 1.10 2/3 72 1.20 1.10 2.20 2.00 1.50 1.00 1.50 90 2/24/72 1.30 1.00 2.20 2.00 1.50 1.00 1.90 -- 3/20/72 1.40 1.30 2.10 1.70 1.30 1.00 1.60 .80 5/4/72 2.00 1.40 2.20 2.10 1.70 1.20 2.10 1.30 8/1/72 1.50 1.10 2.00 2.00 1.10- .90 1.60 .25 9/6/72 2.00 1.60 2.10 1.95 1.85* .90 1.60 .05 9/11/72 1.90 1.50 1.80 2.00 1.25 1.00 1.70 .05 179 TABLE C-l TOTAL PRESSURE CELL DATA TOTAL PRESSURE CELL G7-Horiz. . 67-2 Vert. 67-3 Vert. INITIAL ELEVATION 83.60. 83.78 83. 48 Date 1* WI S? I W S I W 10/15/71 9.0 4.3 5.0 7.7 3.0 3.5 8.1 3.5 4 10/21/71 9.5 4.9 5.7 8.2 3.6 4.1 8.3 3.7 4. 10/28/71 10.8 6.0 6.9 10.1 5.2 6.1 9.2 4.5 5. 11/4/71 11.8 7.0 8.1 10.2 5.2 6.1 9.8 5.0 6. 11/10/71 13.9 9.1 10.5 12.8 8.2 9.3 11.1 6.3 7. 11/12/71 16.3 11.7 13.2 --- --- --- 13.3 8.6 9. 11/15/71 16.5 11.9 13.4 13.1 8.5 9.7 13.1 8.5 9. 11/18/71 16.5 11.9 13.4 12.8 8.2 9.3 12.8 8.2 9. 11/22/71 16.6 12.0 13.5 12.2 7.7 8.8 12.5 8.0 9. 12/1/71 16.9 12.2 13.7 12.7 8.1 9.2 12.0 7.3 8. 12/15/71 17.2 12.7 14.2 13.9 9.1 10.5 11.4 6.9 7. 12/30/71 17.7 13.0 14.6 --- --- --- 11 1 6.3 7. 1/13/72 17.8 13.1 14.7 15.0 10.2 11.8 10.7 6.1 7. 2/3/72 18.0 13.2 15.1 15.8Discontinued 10.5 6.0 7. 2/24/72 17.9 13.2 14.9 15.9 ' 10.3 5.8 6. 3/20/72 18.0 13.2 15.1 16.3 10.3 5.8 6. 5/4/72 18.0 13.2 15.1 16.6 . 10.2 5.5 6. 8/1/72 17.3 12.7 14.2 --- 9.5 4.9 5. 9/6/72 1.7.3 12.7 14.2 --- 9.7 5.1 6. * I - INSTRUMENT READING 1“ W - TOTAL PRESSURE, WATER CALIBRATION, Psi # S - TOTAL PRESSURE, SAND CALIBRATION, Psi NOTE: CELL G7-2 GAVE ERRATIC DATA (MALFUNCTIONED) AND THESE VALUES ARE AN AVERAGE OF FOUR DIFFERENT READINGS. ooomooooowwxoOkuocNowwt—t 180 1" J ljiplhm AHQ:< M+ s# R M S R M S 10/14/71 0 180 .90 0 135 .68 0 340 1.70 LARGE 10/14/71 0 210 1. 05 0 260 1.30 0 340 1. 70 LARGE 10/14/71 0 110 1.10 0 130 1.30 0 190 1. 90 INTER. 10/14/71 0 120 1. 20 0 120 1.20 0 150 1.50 INTER. .11/11/71 0 135 1.35 20 160 1.40 62 240 1.78 INTER. 11/11/71 0 40 . 80 20 70 1. 00 55 150 1. 9o SMALL Elevation ‘ -25 in. ~50 in. ' -75 in. 3/20/72 25 3/20/72 30 Elev. below 180 3.10 25 155 2.50 80 185 3.20 90 240 3.00 SMALL 230 3.00 130 2.80 3.00 SMALL LOWER SLUDGE LAYER sludge top -2-1/2 ft. -5 ft. -7-1/2 ft. TORQUE WRENC 11/11/71 155 345 1. 90 200 440 2.40 CAPACITY 1SMALL 11/11/71 140 280 2. 80 205 330 2.50 EXCEEDED SMALL Elevation -25 in. -40 in. 3/20/72 235 435 4. 00 - -- -- SMALL *R ROD FRIC TION READING +M MAX. READING #S SHEAR STRENGTH, T/MZ 1 a 6-118 v EN IIUNAL CONSOLJII/i "1031 In“: 1' .71 .5111ng -.1 1, 111111.11 water content 250%, wt. dry SPO’CiillUn 26. 5 5111:). February'15, 1972 Limo 7—‘71139171-61-(111‘121- time dial reaging time dial reading £23“- In. x 104 rnin. in. x 10 rnin. in. x 10 load kg/cmZ load 1 kg/cm‘Z load 4 kg/cmz 0.00 0 0.00 0 0.00 0 0.25 311 0.10 120 0.10 115 0.50 395 0.25 185 0.25 180 1.00 522 0.50 250 0.50 255 2.25 700 1.00 340 1.00 355 4.00 836 2.25 475 2.25 525 6.25 928 4.00 575 4.00 660 9.00 980 6.25 640 6.25 760 12.25 1006 9.00 675 9.00 845 16.00 1031 12.25 705 12.25 873 20.25 1048 16.00 720 16.00 903 2 .00 1063 20.25 740 20.25 933 36.00 1082 25.00 750 25.00 950 49.00 1093 36.00 770 36.00 977 120.007 1128 49.00 785 49.00 993 240.00 1147 120.00 825 120.00 1043 580.00 1168 240.00 856 240.00 1074 1440.00 1200 580.00 890 580.00 1103 1440.00 930 1440.00 1137 2 2 2 load kg/cm load 2 kg/cm load 8 kg/cm 0.00 0 0.00 0 0.00 0 0.10 115 0.10 95 0.10 60 0.25 175 0.25 125 0.25 90 0.50 244 0.50 153 0.50 125 1.00 331 1.00 185 1.00 170 2.25 470 2.25 240 2.25 240 4.00 570 4.00 300 4.00 305 6.25 630 6.25 425 6.25 350 9.00 670 9.00 480 9.00 390 12.25 697 12.25 510 12.25 420 16.00 718 16.00 533 16.00 440 20.25 735 20.25 544 20.25 460 25.00 750 25.00 560 25.00 475 36.00 765 26.00 570 36.00 495 49.00 785 49.00 595 , 49.00 510 120.00 832 120.00 635 120.00 555 240.00 863 240.00 655 240.00 580 580.00 897 580.00 675 - 580.00 600 1440.00 937 1440.00 710 1440.00 640 171/1 .11"-1 r? i-‘—2 CONVENTIONAL CONSOLIDATION DATA Sludge U-S-l, initial water content 306%, wt. dry specimen 23. 9 gms. _February 28, 1972 time dial reading time dial reading time dial reading 1min. in. x 10 nnhi. in. x 10 rnin. in. X 104 load .1 kg/cmZ load .4 kg/cm2 load 1.6 kg/crn2 0.00 0 0.00 O 0.00 O 0.10 130 0.10 65 0.10 70 0.25 175 0.25 105 0.25 110 0.50 215 0.50 145 0.50 153 1.00 275 1.00 210 1.00 210 2.25 390 2.25 300 2.25 283 4.00 505 4.00 373 4.00 337 (1.25 605 6.25 423 6.25 380 9.00 690 9.00 460 9.00 409 12.25 755 12.25 480 12.25 455 1 .00 805 16.00 495 16.00 483 20.25 835 20.25 510 20.25 500 25.00 855 25.00 515 25.00 512 36.00 885 36.00 530 36.00 525 49.00 905 49.00 540 49.00 537 120.00 945 120.00 565 120.00 565 240.00 965 240.00 590 240.00 583 580.00 995 580.00 610 ’ 580.00 605 1400.00 1025 1480.00 635 1450.00 635 2 2 p 2 load..2'kg/cn1 10ad..8 kg/krn load 3.2 kg/cna 0.00 0 0.00 0 0.00 0 0.10 50 0.10 70 0.10 95 .0.25 85 0.25 110 0.25 140 0.50 120 0.50 155 0.50 192 1.00 175 1.00 220 1.00 262 2.25 260 2.25 320 2.25 360 4.00 330 4.00 410 4.00 428 6.25 380 6.25 465 6.25 475 .9.00 420 9.00 485 9.00 507 12.00 450 12.25 495 12.25 325 16.00 470 16.00 500 16.00 540 20.25 490 20.25 505 20.25 550 25.00 500 25.00 515 25.00 560 36.00 520 36.00 520 36.00 570 49.00 535 49.00 525 49.00 578 120.00 575 120.00 545 120.00 603 240.00 600 240.00 560 120.00 620 580.00 630 580.00 570 580.00 640 1460.00 665 1440.00 585 1410.00 660 load . 8 kg/cm2 720.00 190 TABLE F~3 CONVENTIONAL CONSOLIDATION DATA wt. dry specimen 24. 7 gms. 185 Sludge u-3-3, initial water content 271%, March 11, 1972 time dial reading time dial reading time dial reaging min. in. x 104 min. in. x 10 min. in. x 102 load .1 kg/cm2 load . 4 kg/crn2 load 1. 6 kg/cmz 0.00 0 0.00 0 0.00 0 0.10 70 0.10 43 0.10 87 0.25 105 0.25 72 0.25 135 0.50 145 0.50 105 0.50 195 1.00 200 1.00 150 1.00 280 2.25 290 2.25 227 2.25 420 4.00 375 4.00 290 4.00 498 6.25 455 6.25 337 p 6.25 550 9.00 510 9.00 372 9.00 587 12.25 555 12.25 400 12.25 600 16.00 585 16.00 420 16.00 605 20.25 610 20.25 433 20.25 610 25.00 620 25.00 448 25.00 615 36.00 655 36.00 468 36.00 622 49.00 665 49.00 485 49.00 628 120.00 700 120.00 540 120.00 640 240.00 725 240.00 568 240.00 650 580.00 760 580.00 583 580.00 662 1580.00 795 1460.00 606 1480.00 682 5 2 2 ‘ 2 load . 2 kg/cm load . 8 kg/cm load 3. 2 kg/cm 0.00 0 0.00 0 0.00 0 0.10 30 0.10 62 0.00 75 0.25 53 '0.25 93 0.25 126 0.50 80 0.50 127 0.50 185 1.00. 120 1.00 173 1.00 263 2.25 187 2.25 242 2.25 378 4.00 247 4.00 286 4.00 464 6.25 293 6.25 307 6.25 520 9.00 327 9.00 320 9.00 551 12.25 350 12.25 330 12.25 570 16.00 373 16.00 337 16.00 580 ‘ 20.25 388 20.25 342 20.25 583 25.00 400 25.00 348 25.00 590 36.00 415 36.00 357 36.00 602 49.00 428 49.00 365 49.00 610 120.00 468 120.00 382 120.00 627 240.00 492 240.00 392 240.00 642 580.00 520 580.00 412 580.00 658 1470.00 555 1450.00 460 1430.00 683 load . 8 kg/cm2 1444.00 192 21' ‘Acamufl 5' IBILQ'. I‘-...‘-.'. 31.4 I'. March 27, 1972 TABLE F-4 CONVENTIONAL CONSOLIDATION DATA Sludge U-3-7, initial water content 299%, wt, dry specimen 2.3. 0 grams. time dial reading time dial reading time ' dial rea ing rnin. in. x 10 rnin. in. x 10 rnin. in. x 10 load .1 kg/cmZ load . 4 kg/cm2 load 1.6 kg/cmZ 0.00 O 0.00 0 0.00 O 0.10 125 0.10 40 0.10 90 0.25 170 0.25 63 0.25 145 0.50 220 0.50 93 0.50 213 1.00 300 1.00 133 1.00 292 2.25 440 2.25 200 2.25 410 4.00 585 4.00 262 4.00 475 6.25 730 6.25 340 6.25 516 9.00 850 9.00 383 9.00 547 12.25 945 12.25 401 12.25 575 16.00 1020 16.00 414 16.00 594 20.25 1075 20.25 423 20.25 601 25.00 1110 25.00 430 25.00 610 . 36.00 1145. 36.00 440 36.00 622 49.00 --- 49.00 448 49.00 --- 120.00 1215 120.00 460 120.00 637 240.00 1235 240.00 468 240.00 643 580.00 1270 580.00 478 580.00 655 1660.00 1310 1430.00 500 1450.00 660 2 2 ‘ 2 load .2 kg/crn load .8 kg/crn load 3.2 kg/crn 0.00 0 0.00 0 0.00 O 0.10 35 0.10 50 3: $3 2; 3: $3 133 lee hlr lleer l. 00 122 1. 00 140 increment no good 2.25 187 2.25 195 4.00 241 4.00 250 6.25 283 6.25 298 9.00 315 9.00 322 12.25 335 12.25 225 16.00 354 16.00 345 20.25 368 20.25 351 25.00 380 25.00 355 36.00 400 36.00 365 49.00 410 49.00 373 120.00 440 120.00 389 240.00 460 240.00 398 580.00 478 580.00 406 1460.00 498 1420.00 422 1530.00 600 x 5.2“. .r'l 4...me 187 TABLE F-S CONVENTIONAL CONSOLIDATION DATA Sludge U-3-8, initial water content 272%, wt. dry specimen 24. 5 gms. ' April 3, 1972 time dial reading time dial reaging time dial reading min. in.x 104 min. in. x 10 min. in. x 10 load .1 kg/cmZ load .4 kg/cmZ load 1.6 kg/cm2 0. 00 0 . 0. 00 0 0. 00 0 0.10 115 0.10 60 0. 10 108 0.25 155 0.25 93 0.25 158 0.50 200 0.50 130 0.20 210 1.00 260 1.00 182 1.00 280 2.25 370 2.25 253 2.25 383 4.00 470 4.00 325 4. 00 433 6.25 590 6.25 407 6.25 465 9. 00 690 9.00 465 9.00 488 12.25 735 12.25 510 12.25 503 16.00 760 16.00 532 16.00 515 . 20. 25 775 20. 2‘5 553 20. 25 525 25. 00 785 25. 00 - 570 25. 00 532 36.00 805 36.00 --- 36.00 550 49.00 815 49. 00 --- 49.00 558 120.00 840 120.00 640 120.00 580 240.00 560 240.00 657 240.00 593 580.00 890 580.00 673 580.00 610 1465. 00 925 1420. 00 713 1440. 00 ' 630 2 p 2 ~ 2 load . 2 kg/cm load .8 kg/cm load 3.2 kg/cm 0. 00 0 _ 0. 00 0 0. 00 0 'o. 10 4o _ o. 10 43 0. 25 63 0. 25 ' 145 0. 50 95 porous stone hung up 150. 00 210 1.00 138 on ring--reading of l. 00 295 2. 25 205 . 340 obtained-~new 2. 25 428 4. 00 . 253 increment applied 4. 00 515 6. 25 290 6. 25 570 9. 00 315 9. 00 600 12. 25 333 12. 25 622 16. 00 345 . 16. 00 637 20. 25 358 20. 25 648 25. 00 368 25. 00 657 36.‘ 00 325 36. 00 670 49. 00 397 . 49. 00 678 120. 00 430 120. 00 705 240. 00 453 240. 00 722 580. 00 480 580. 00 743 1430.00 518 1425.00 770 '1 ABLE. I‘-6 CONVENTIONAL CONSOLIDA‘I‘ION DA'I A Sludge 1143—9, initial water content 313%, wt. dry specimen 22. (J 81.18. April 9, 1972 time dial reading time dial reading time dial reading rnin. in. x 10 rnin. in. x 10 rnin. in. x 104 load .1 kg/cm‘Z load .4 kg/cm2 load 1.6 kg/cmz 0.00 0 0.00 0 0.00 0 0.10 90 0.10 53 0.10 115 0.25 130 0.25 77 0.25 158 0.50 175 0.50 108 0.50 208 1.00 240 1.00 150 1.00 275 2.25 355 2.25 215 2.25 378 4.00 505- 4.00 270 4.00 465 6.25 660 6.25 320 6.25 512 9.00 795 9.00 405 9.00 532 12.25 925 12.25 472 12.25 550 16.00 1035 16.00 518 16.00 565 20.25 1125 20.25 550 20.25 580 25.00 1185 25.00 580 25.00 590 36.00 1255 36.00 610 36.00 602 49.00 1295 49.00 625 49.00 610 120.00 1365 120.00 655 120.00 632 240.00 1405 240.00 690 240.00 645 580.00 1435 580.00 715 580.00' 660 1495.00 1495‘ 1450.00 748 1430.00 682 2 _ 2 2 load .2 kg/cni load .8 kg/cnu load 3.2 kg/crn 0.00 0 0.00 0 0.00 0 0.10 30 0.10 62 0.10 85 0.25 50 0.25 90 0.25 130 0.50 73 0.50 115 0.50 182 1.00 110 1.00 148 1.00 260 2.25 175 2.25 180 2.25 390 4.00 230 4.00 200 4.00 505 6.25. 280 6.25 215 6.25 590 9.00 315 9.00 225 9.00 635 12.25 350 12.25 237 12.25 662 16.00 380 16.00 243 16.00 682 20.25 400 20.25 252 20.25 695 25.00 415 25.00 258 25.00 705 36.00 440 36.00 270 36.00 720 49.00 460 49.00 , 275 49.00 730 120.00 495 120.00 292 120.00 755 240.00 520 240.00 305 240.00 770 580.00 550 580.00 315 580.00 782 1460.00 595 1440.00 333 1480.00 802 Le 189 TABLE F-7 CONVENTIONAL CONSOLIDATION DATA Sludge L-2-l bag 1, initial water content 256%, wt. dry specimen 26. 2 April 18, 1972 gms. time min. load .1 kg/cmz dial reading in. x 10 time min. dial reading in. x 104 load . 4 kg/cm2 time min. dial reading in. x 10 load 1. 6 kg/cmz 0.00 0 0.00 0 0.00 0 0.10 120 0.10 45 0.10 60 0.25 170 0.25 75 0.25 90 0.50 215 0.50 110 0.50 128 1.00 280 1.00 155 1.00 180 2.25 590 2.25 230 2.25 255 4.00 510 4.00 293 4.00 315 6.25 630 6.25 335 6.25 355 9.00 730 9.00 370 9.00 382 12.25 820 12.25 395 12.25 400 16.00 895 16.00 412 16.00 410 20.25 945 20.25 430 20.25 420 25.00 985 25.00 443 25.00 430 36.00 A 1030 36.00 465 36.00 445 49.00 1055 49.00 475 49.00 455 120.00 1105 120.00 515 120.00 480 240.00 1140 240.00 535 240.00 500 580.00 1170 580.00 557 580.00 518 1430.00 1210 1470.00 645 1480 540 2 2 2 load . 2 kg/cm load .8 kg/cm load 3.2 kg/cm 0.00 0 0.00 0 0.00 0 0.10 43 0.10 60 0.10 75 0.25 70 0.25 93 0.25 115 0.50 100 0.50 133 0.50 162 1.00 140 1.00 188 1.00 230 2.25 210 2.25 275 2.25 330 4.00 265 4.00 350 4.00 395 6.25 312 6.25 443 6.25 440 9.00 352 9.00 493 9.00 470 '12.25 383 12.25 515 12.25 495 16.00 405 14.00 535 16.00 512 20.35 422 20.25 545 20.25 525 25.00 440 25.00 553 25.00 530 36.00 458 36.00 563 36.00 545 ' 49.00 472 49.00 567 49.00 552 120.00 515 120.00 572 120.00 572 240.00 540 240.00 578 240.00 590 580.00 570 580.00 581 580.00 608 1450.00 595 1530.00 600 1445.00 620 ifil‘ 1K.- 12' rava- :..sr-sm.m_n1 f l l‘JU TABLE F-8 BISHOP CONSOLIDATION DATA Sludge U-3-10, initial water content 283%, wt. dry specimen 18.1 gms. ‘ April 29, 1972‘ time dial reading time dial reading time dial reading min. in. x 10 min. in. x 10 min. in. x 10 load . 1 kg/cm2 load .4 kg/cmZ load 1.6 kg/cm'Z 0.00 0 0.00 O 0.00 0 0.10 220 0.10 55 0.10 65 0.25 270 0.25 80 0.25 95 0.50 330 0.50 110 0.50 132 1.00 420 1.00 ‘ 155 1.00 182 2.25 560 2.25 225 2.25 255 4.00 670 4.00 275 4.00 315 6.25 745 6.25 315 6.25 365 9.00 800 9.00 345 9.00 395 12.25 '840 12.25 365 12.25 420 16.00 860 16.00 385 16.00 442 20.25 875 20.25 400 20.25 458 25.00 885 25.00 410 25.00 470 36.00 905 36.00 435 36.00 490 49.00 920 49.00 450 49.00 505 120.00 950 120.00 495 120.00 545 240.00 975 240.00 525 240.00 570 580.00 1010 580.00 565 580.00 600 1440.00 1045 1460.00 600 ' 1420.00 630 . 2 2 ‘ ‘ 2 load . 2 kg/cm load . 8 kg/cm . load 3. 2 kg/cm 0.00 O 0.00 0 0.00 0 0.10 45 0.10 60 _ 0.10 55' 0.25 70 0.25 95 0.25 85‘. 0.50 100 0.50 130 0.50 120 1.00 135 1.00 180 1.00 165 2.25 195 2.25 258 2.25 232 4.00 235 4.00 318 4.00 288 6.25 270 6.25 365 6.25 332 9.00 295 9.00 402 9.00 362 12.25 315 12.25 430 12.25 388 16.001 330 16.00 450 16.00 405 20.25 345 20.25 468 20.25 420 25.00 355 25.00 480 25.00 430 36.00 370 36.00 502 1 36.00 450 49.00 385 49.00 520 ‘ 49.00 465 120.00 425 120.00 560 120.00 505 242.00 460 240.00 590 240.00 ~ 528 580.00 500 580.00 625 580.00 548 1415.00 535 1450.00 660 1440.00 575 191 May 16, 1 972 TABLE F-9 BISHOP CONSOLIDATION DATA Sludge U-3-12, initial water content 278%, wt. dry specimen 18. 7 gms. time min. dial reading in. x 104 load .1 kg/cm2 time min . dial reading in. x 10 load . 4 kg/cmz time min. load 1. 6 kg/cm2 dial rea in. x 10 ging 0.00 0 0.00 0 0.00 0 0.10 130 0.10 40 >0.10 62 0.25 190 0.25 62 0.25 93 0.50 262 0.50 90 0.50 130 1.00 365 1.00 130 1.00 178 2.25 540 2.25 193 2.25 252 4.00 675 4.00 240 4.00 312 6.25 775 6.25 275 6.25 355 9.00 835 9.00 2987 9.00 390 12.25 870 12.25 320 12.25 412 16.00 890 16.00 338 16.00 433 20.25 910 20.25 355 20.25 450 25.00 920 25.00 362 25.00 462 36.00 945 36.00 385 36.00 483 49.00 , 955 49.00 405 49.00 495 120.00 980 120.00 440 120.00 535 240.00 1005 240.00 472 240.00 562 580.00 1040 580.00 515 580.00 590 1440.00 1070 1470.00 560 1490.00 622 2 2 2 load . 2 kg/cm load . 8 kg/cm load 3. 2 kg/cm 0.00 0 0.00 0 0.00 0 0.10 35 0.10 555 0.10 55 0.25 55 0.25 90 0.25 85 0.50 78 0.50 123 0.50 115 1.00 110 1.00 175 1.00 162 2.25 160 2.25 248 2.25 230 4.00 203 4.00 308 4.00 280 .6.25 225 6.25 355 .6.25 328 9.00 245 9.00 387 9.00 355 12.25. 262 12.25 412 12.25 380 16.00 275 16.00 532 16.00 400 20.25 285 20.25 448 20.25 412 25.00 295 25.00 462 25.00 428 '36.00 313 36.00 482 36.00 448 49.00 325 49.00 495 49.00 458 120.00 358 120.00 540 120.00 493 240.00 385 240.00 572 240.00 518 ‘ 580.00 412 580.00 608 580.00 540 1440.00 450 1440.00 640 1480.00 570 TABLE F- 10 192 BIS] [OP CONSOLIDATION DATA Sludge L-2-2 bag 1, initial water content 274%, wt. dry specimen 19. 0 May 24. 1972 gms. time dial reading time dial reading time dial reading min. in. x 10 min. in. x 10 min. in. x 104 load .1 kg/cmZ load .4 kg/cnn2 load 1.6 kg/cmZ 0.00 0 0.00 O 0.00 0 0.10 195 0.10 38 0.10 60 0.25 265 0.25 62 0.25 90 0.50 340 0.50 88 0.50 125 1.00 445 1.00 125 1.00 175 2.25 625 2.25 187 2.25 243' 4.00 800 4.00 235 4.00 300 6.25 945 6.25 272 6.25 338 9.00 1050 9.00 298 9.00 370 12.25 1110 12.25 320 12.25 395 16.00 1150 16.00 340 16.00 405 20.25 1175 20.25 350 20.25 421 25.00 1190 25.00 365 25.00 432 36.00 1210 36.00 385 36.00 458 49.00 1220 49.00 400 49.00 468 120.00 1255 120.00 940 120.00 505 240.00 1270 240.00 470 240.00 528 580.00 1290 580.00 500 580.00 550 1440.00 1440.00 535 1530.00 580 2 2 2 load . 2 kg/cm load . 8 kg/cm load 3. 2 kg/cm 0.00 O 0.00 0 0.00 0 0.10 25 0.10 62 0.10 60 0.25 45 0.25 90 0.25 90 0.50 ‘63 0.50 123 0.50 122 1.00 90 1.00 170 1.00 167 2.25 135 2.25 240 2.25 234 4.00 175 4.00 298 4.00 285 6.25 205 6.25 342 6.25 327 9.00 225 9.00 372 9.00 353 12.25 242 12.25 400 12.25 373 16.00 255 16.00 418 16.00 390 20.25 263 20.25 432 20.25 400 25.00 273 25.00 448 25.00 412 36.00 285 36.00 470 36.00 435 49.00 300 49.00 485 49.00 450 120.00 330 120.00 522 120.00 478 240.00 355 240 00 550 240.00 498 580.00 383 580 00 578 580.00 520 1440.00 420 1440 00 610 1510.00 545 193 TABLE F-ll BISHOP CONSOLIDATION DATA Sludge L-2-3 bag 1, initial water content 263%, wt. dry specimentl‘). 4 June 5, 1972 gms. time dial reading time dial reading time dial reading min. in. x 104 'min. in. x 10 min. in. x 10 load . 1 kg/cmZ load .4 kg/cmZ load 1.6 kg/cmZ 0.00 O 0.00 0 0.00 0 0.10 140 0.10 45 0.10 64 0.25 203 0.25 70 0.25 92 0.50 232 0.50 98 0.50 123 1.00 372 1.00 136 1.00 170 2.25 545 2.25 198 2.25 238 4.00 695 4.00 244 4.00 292 6.25 818 6.25 280 6.25 337 9.00 890 9.00 305 9.00 363 12.25 940 12.25 322 12.25 390 16.00 970 16.00 338 16.00 406 20.25 990 20.25 352 20.25 420 25.00 1042 25.00_ 363 25.00 430 36.00 1020 36.00 385 36.00 453 49.00 1032 49.00 --- 49.00 480 120.00 1058 120.00 433 120.00 503 240.00 1075 240.00 463 240.00 525 580.00 1095 580.00 492 580.00 548 1440,00 1125 1400.00 522 1490.00 580 load . 2 kg/cm load . 8 kg/cm load 3. 2 kg .cm . 0.00 0 0.00 0 0.00 0 0.10 30 . 0.10 63 0.10 60 0.25 45 0.25 93 0.25 85 0.50 63 0.50 127 0.50 116 1.00 90 1.00 176 1.00 160 2.25 133 2.25 248 2.25 225 4.00 165 4.00 304 4.00 280 6.25 190 6.25 347 6.25 320 9.00 208 9.00 375 9.00 348 12.25 ‘ 222 12.25 400 12.25 370 16.00 233 16.00 418 16.00 391 20.25 243 20.25 432 20.25 405 25.00 251 25.00 443 25.00 4.8 36.00 270 36.00 463 36.00 435 49.00 278 49.00 475 49.00 468 120.00 308 120.00 513 120.00 485 240.00 328 240.00 538 240.00 507 580.00 358 580.00 565 ‘ 580.00 534 1460.00 .390 1570.00 590 1270.00 560 TABLE F—12 BISHOP CONSOLIDATION DATA 194 Sludge U-5-2, initial water content 263"", wt. dry specimen 19.6 gms. June 19, 1972 ‘._.».| r“ ." Jl" 5P1 tinu: (Hal reading tin“: (Hal reading Linn: (Mal reaging min. in. x 104 min. in. x 10 min. in. x 10 load . 1 kg/cmz load .4 kg/cmz load 1.6 kg/cmz' 0.00 O 0.00 0 0.00 0 0.10 89 0.10 50 0.10 65 0.25 150 0.25 75 0.25 100 0.50 210 0.50 105 0.50 135 1.00 290 1.00 150 1.00 187 2.25 420 2.25 215 2.25 265 4.00 527 4.00 265 4.00 325 6.25 595 6.25 303 6.25 377 9.00 630 9.00 330 9.00 413 12.25 660 12.25 350 12.25 442 16.00 678 16.00 366 16.00 463 20.25 690 20.25 382 20.25 480 25.00 700 25.00 393 25.00 495 36.00 715 36.00 418 36.00 520 49.00 725 49.00 428 49.00 535 120.00 753 120.00 473 120.00 575 240.00 773 240.00 502 240.00 600 580.00 798 580.00 538 580.00 633 1440.00 830 1430.00 580 1470.00 670 . 2 2 2 load . 2 kg/cm load . 8 kg/cm load . 8 kg/cm 0.00 0 0.00 0 0.00 O 0.10 35 0.10 64 1095.00 67 0.25 53 0.25 96 0.50 77 0.50 134 1.00 108 1.00 187 2 2. 25 156 2. 25 265 load '1 kg/Cm 4.00 192 4.00 328 6.25 220 6.25 375 0.00 0 9.00 235 9.00 410 245.00 377 12.25 253 12.25 438 16.00 265 16.00 460 20.25 272 20.25 474 25.00 283 25.00 490 36.00 295 36.00 510 49.00 312 49.00 523 120.00 342 120.00 570 240.00 365 240.00 595 580.00 398 580.00 628 1430.00 435 1470.00 670 'l'A ”LI". :7‘. i "- SINC 1.1') 1"!"19. l"".".lrlz\l'l‘ CONSOLIDATION DA'J‘A Siudge U~3—4 Sludge U-3—6 initial water content 302% initial water content '? initial void ratio 5. 64 initial void ratio 5. 48 wt. dry specimen 23. 1 gms. wt. dry specimen 23. 7 gms. load o—. 24 kg/omZ 3/23/72 load o-. 24 kg/cmz 3/25/72 time dial reading time dial reading rnin. in. x 104 rnin. in. x 10 0. 00 O 0. 00 O O. 10 190 0.10 220 O. 25 273 0. 25 330 0. 50 378 0. 50 455 if 1.00 520 1.00 630 l 2. 25 776 2. 25 930 ' 4.00 1018 4.00 1185 6.25 1200 6.25 1358 i 9. 00 1328 9. 00 1470 , 12.25 1397 12.25 1520 E 16.00 1448 16.00 1550 g 20. 25 1472 20. 25 1570 L 25. 00 1490 25. 00 1585 36. 00 1510 36. 00 1605 49. 00 1518 49. 00 1620 120. 00 1540 120. 00 1648 240. 00 1558 240. 00 1678 580. 00 1570 580. 00 1705 1312.00 1597 1440.00 1745 Sludge u-3_5 initial water content 291% initial void ratio 5. 40 wt. dry specimen 24.0 gms. load 0-. 24 kg/cmz 3/24/72 0.00 0 0.10 265 0.25 380 0.50 500 1.00 680 2.25 993 4.00 1258 6.25 1448 9.00 1550 12.25 1610 16.00 1640 20.25 1660 25.00 1673 36.00 1705 49.00 1710 120.00 1737 240.00 1755 580.00 1783 1450.00 1805 196 Iii, 00mm 00.0HmH mm4~ 00.0m0H 054m 00.0mm ome 00.00m 044m 00.04N 04mH 00.04N mH4N 00.0NH 4NmH 00.0NH 00mm 00.04 wnmfi 00.04 00mm 00.0m NONH 00.0m 04mm 00.m~ m4- 00.m~ 0mmm m~.0m 0mm~ mm.0m m0m~ 00.0H womfi 00.0H 0mm~ mN.N~ owHH mm.- oofim 00.0 mmHH 00.0 000m mm.0 m00~ m~.0 omnfi 00.4 040 00.4 0an mN.N mm“ mm.~ 0M0 00.H 0mm 00.H one 0m.0 00m 0m.0 004 mN.0 00m m~.0 0mm 0H.0 00m 0H.0 0 00.0 0 00.0 40H x .20 .cflflh 40H x .:M .cwch mcflwmon .220 053 wage“: ~30 083 20.55. 488}: 3:0 32 3me MERE 3. .-o ooofi .mEW m .0; 3.888% who #3 04 .m GEM.” 08> 33¢: «boom osoozoo .8005 332: 4-74 owoflm .erm N. .0N coawoeamgpv .03 m4 .4 03mg 20> 33¢: o004m useucoo nouns? Hanna“ 94-: owogm 00 .03 mm .m 00:3 08> ESE“ 04mm pseuaoo Meow? H.300: 2-90 owoim .me 7mm noeflooqmgp0 .03 mm .4 03.2 06> 330C“ omega “coucoo Hood? 030?: 74-: omogm umSGHocooII.qHIm Manda 198 TABLE F—lS UNDISTURBED SAMPLE DATA, RAPID LOAD INCREMENTS Sample 8 test No. 1 Sample B test No. 2 initial water content 237% initial water content 234% initial void ratio 4.65 initial void ratio 4.65 wt. dry specimen 29.5 gms. wt. dry specimen 29.5 gms. load apglied every 25 min. 10/12/72 load applied every 15 min. 10/17/75 load dial reading load 2 dial reading kg/cm in. x 104 kg/cm in. x 104 0.00 0 0.00 0 0.10 296 0.05 126 0.20 548 0.075 192 0.30 792 0.10 255 0.40 1002 0.15 409 0.60 1382 0.20 500 0.80 1714 0.25 649 1.00 1974 0.30 806 1.50 2450 0.35 919 2.00 2775 0.40 1025 3.00 3213 0.50 1226 4.50 3602 0.60 1396 0.80 1712 1.00 1959 1.50 2422 2.00 2733 1.00 2654 0.40 2427 1.04 2554 1.75 2727 2.24 2893 3.24 3240 4.24 3513 0.40 3000 0.10 2638 199 TABLE F-15.-—Continued. Sample F test No. 1 Sample F test No. 2 initial water content 165% initial water content 168% initial void ratio 3.50 initial void ratio 3.52 wt. dry specimen 39.4 gms. wt. dry specimen 38.8 gms. load applied every 15 min. 11/9/72 load applied every 15 min. 11/15/72 load dial reading load dial reading kg/cm in. x 104 kgjcm in. x 104 0.00 0 0.00 0 0.05 65 0.05 58 0.10 132 . 0.10 121 0.20 261 0.20 233 0.30 408 0.30 357 0.40 517 0.40 449 0.50 607 0.50 536 0.60 707 0.60 615 0.70 816 0.70 699 0.80 919 0.80 796 1.00 1093 1.00 993 1.50 1497 1.50 1414 2.00 1838 2.00 1735 3.00 2272 3.00 2192 4.50 2691 4.50 2625 1.00 2412 1.00 2335 0.10 1904 0.10 1799 200 TABLE F—l6 UNDISTURBED SAMPLE DATA Sample 8 test no. 3, initial water content 230%, wt. dry specimen 30.4 Oct. 23, 1972 __.-I. gms time Sufi Li 1.1—".7. J I; I time dial reading dial reading time dial reading min. in. x 104 min. in. x 104 min. in. x 104 load .05 kg/cm2 load .40 kg/cm2 load 1.6 kg/cm2 0.00 0 0.00 O 0.00 0 0.10 43 0.10 74 0.10 93 0.25 54 0.25 107 0.25 133 0.50 66 0.50 145 0.50 178 1.00 78 1.00 195 1.00 245 2.25 90 2.25 259 2.25 351 4.30 96 4.00 300 4.00 431 6.25 99 6.25 329 6.25 488 12.25 103 9.00 350 12.25 559 36.00 111 12.25 364 25.00 620 750.00 132 16.00 373 50.00 655 2 36.00 405 100.00 690 load .10 kg/cm 100.00 443 720.00 780 0.00 0 720.00 514 2 0.10 32 2 load 3.2 kg/cm 0.25 45 load .80 Egigm 0.00 o 0.50 60 0.00 0 0.10 91 1.00 78 0.10 95 0.25 126 2.25 99 0.25 133 0.50 166 4.00 111 0.50 180 1.00 225 6.50 120 1.00 248 2.25 322 9.00 125 2.25 352 4.00 410 12.25 130 4.00 430 6.25 466 100.00 158 6.25 485 9.00 510 700.00 185 9.00 520 12.25 542 2 12.25 540 20.00 583 load .20 kg/cm 20.00 591 40.00 630 0.00 0 100.00 664 100.00 660 0.10 48 310.00 720 300.00 706 0.25 68 730.00 749 700.00 738 0.50 92 2 1.00 122 load 1.8 kg/cm 2.25 158 0.00 0 4.00 180 720.00 -259 6.25 194 2 9.00 204 load .1 kg/cm 12.25 212 0.00 O 36.00 235 375.00 -575 190.00 270 710.00 296 so. ’a'fl‘l 201 TABLE F417 UNDISTURBED SAMPLE DATA Sample 8 test no. 4, initial water content 196%, wt. dry specimen 34.7 Nov. 1, 1972 gms time dial reading time dial reading time dial reading min. in. x 104 min. in. x 104 min. in. x 10 load .05 kg/cm2 load .40 kg/cm2 load 1.6 kg/cm2 0.00 0 0.00 0 0.00 0 0.10 33 0.10 48 0.10 77 0.25 44 0.25 66 0.25 106 0.50 55 0.50 87 0.50 138 1.00 69 1.00 104 1.00 183 2.25 85 2.25 122 2.25 260 4.00 96 4.00 139 4.00 331 7.00 106 6.25 154 6.25 393 9.00 109 12.25 167 9.00 446 12.25 113 16.00 173 15.00 542 16.00 116 66.00 203 25.00 603 27.00 121 100.00 214 55.00 680 100.00 133 300.00 226 100.00 720 300.00 142 675.00 236 300.00 770 730.00 149 (bad load increment) 685.00 782 load .10 kg/cm2 load .80yljgjcm2 load 3.2 kg/cm2 0.00 0 0.00 0 0.00 0 0.10 12 0.10 100 0.10 72 0.25 20 0.25 140 0.25 44 0.50 27 0.50 185 0.50 132 1.00 38 1.00 256 1.00 170 2.25 52 2.25 352 2.25 239 4.00 65 4.00 429 4.00 298 6.25 75 6.50 506 6.25 350 9.00 81 9.00 553 9.00 397 16.00 90 12.25 602 15.00 464 30.00 98 16.00 638 25.00 520 100.00 115 25.00 693 55.00 588 710.00 138 54.00 765 100.00 623 2 100.00 810 300.00 691 load .20 kg/cm 300.00 862 720.00 708 0.00 0 735.00 758 2 0.10 22 load .80 kg/cm 0.25 33 0.00 0 0.50 41 745.00 -228 1.00 65 2 2.25 87 load .10 kgjcm 4.00 100 0.00 O 6.25 112 670.00 -503 9.00 122 15.00 133 30.00 142 100.00 153 300.00 164 775.00 173 202 TABLE F-18 UNDISTURBED SAMPLE DATA Sample F test no. 3, initial water content 170%, wt. dry specimen 39.0 Nov. 27, 1972 gms time dial reading time dial reading time dial reading min. in. x 104 min. in. x 104 min. in. x 104 load .05 kg/cm2 load .40 kg/cm2 load 1.6 kg/cm2 0.00 0 0.00 0 0.00 0 0.10 30 0.10 45 0.10 75 0.25 38 0.25 61 0.25 102 0.50 46 0.50 80 0.50 134 1.00 57 1.00 107 1.00 182 2.25 68 2.25 141 2.35 258 4.00 74 4.00 165 4.00 325 6.25 78 6.25 180 6.25 379 9.00 80 9.00 190 9.00 423 12.25 82 12.25 198 12.25 451 100.00 90 32.00 218 20.00 500 830.00 99 100.00 242 40.00 545 2 700.00 281 100.00 597 load .10 kg/cm 2 300.00 650 0.00 0 load .80 Kglcm 730.00 683 0.10 18 0.00 0 2 0.25 23 0.10 67 load 3.2 kg/cm 0.50 29 0.25 92 ~0.00 1.00 36 0.50 119 0.10 79 2.25 45 1.00 154 0.25 108 4.00 50 2.25 206 0.50 143 6.25 54 4.00 242 1.00 196 9.00 56 6.25 268 2.25 287 100.00 73 9.00 287 4.00 368 600.00 86 12.25 302 6.25 437 2 40.00 360 9.00 493 load .20 RELEN 100.00 385 12.25 ‘534 0.00 0 200.00 405 30.00 635 0.10 26 720.00 435 50.00 670 0.25 ' 34 110.00 720 0.50 44 275.00 750 1.00 56 750.00 783 2.25 72 2 4.00 82 load .80 kglgm 6.25 - 90 0.00 0 12.25 99 660.00 -277 113.00 127 2 740.00 152 load .10 kgjcm 0.00 - 0 650.00 -593 203 TABLE F-19 UNDISTURBED SAMPLE DATA Sample F test no. 4, initial water content 163%, wt. dry specimen 40-1 Dec. 6, 1972 gms time dial reading time dial reading time dial reading min. in. x 10 min. in. x 104 min. in. x 104 load .05 kg/cm2 load .40 kg/cm2 load 1.6 kg/cm2 0.00 0 0.00 0 0.00 0 0.10 28 0.10 28 0.10 75 0.25 34 0.25 37 0.25 99 0.50 40 0.50 48 0.50 126 1.00 47 1.00 62 1.00 167 2.25 57 2.25 84 2.25 239 4.00 63 4.00 100 4.00 g 305 6.25 67 6.25 112 6.25 354 9.00 70 9.00 121 9.00 395 12.25 71 12.25 127 12.25 426 16.00 73 32.00 145 16.00 450 175.00 82 100.00 163 32.00 500 710.00 87 300.00 180 70.00 548 2 660.00 192 134.00 581 load .10 kg/cm 2 414.00 624 0.00 0 load .SOEglcm 1200.00 668 0.10 16 0.00 0 2 0.25 20 0.10 70 _load 3.2 kg/cm 0.50 25 0.25 90 0.00 0 1.00 30 0.50 113 0.10 76 2.25 38 1.00 146 0.25 99 4.00 43 2.25 198 0.50 130 6.25 46 4.00 239 1.00 175 9.00 49 6.25 267 2.25 251 12.25 51 9.00 291 4.00 323 .16.00 52 12.25 309 6.25 388 100.00 64 32.00 350 9.00 442 725.00 77 100.00 391 12.25 482 2 300.00 421 16.00 515 load .20 Iggy/cm 740.00 446 32.00 593 0.00 0 100.00 665 0.10 23 400.00 725 0.25 29 970.00 757 0.50 36 2 1.00 45 load .80 kg/cm 2.25 58 0.00 0 4.00 67 430.00 -264 6.25 73 2 9.00 78 load .10 kg/cm 16.00 84 0.00 0 67.00 99 930.00 -558 360.00 117 710.00 127 I”? run r“. ”" ,--\ \ . ncfiruncwr~b COCO ("300 204 Aramuux.c' COMPUTER PROGRAM FOR LOAD INCREASING LINEARLY WITH TIME FOLI.C‘.‘~’ED BY AN INSTANTANEOUS SURCHARGE APPLICATION 69 7 PROGRAM bLUUbE ( INPUToUUTPUI) DIMENSION P(20o203)o TP(26920U)9 Ul(200)¢ Ud(200)o PPIdUU)o IIKUU) 19 TM1(200)9TM2(200) EN = CONTROL CARD (IF=1.0 HKUHHAM TERMINAILb) ch = COFF. 0F CUNSUL. A 10**3 IN.**d/M1M. (CVI) INTEGER FORM NH : AVG. THICKNESS UF LAYER (IN.) DURINo LINLAR LUAUING NDT = TOTAL TIMF UP LINEAR LUAU 1N MIN. 1?: INCRFMFNTS OF TIME SOLVED AFILR 5UHCHAHGL APPLICATIUN CV1 = COEF. 0F CUVDUL. UF LAYLK DURING LINLAH LUAuINU GAMI TU uAMB : UNIT wT. 0F MATLib Uth IN LthAR LUAU wtthxa GAM4 2 UNIT wT. 0F SUHCHARUE MATtL Ht To H3 = HT. 0F MATtLS IN LINEAR LUAU SEGMENT H4 = HT. 0F SUHCHAHut MATxL CV2 = COEF. 0F CUdSOL. UF LAYLH AFTER SUHCHARGL LOADING PclqM) TU P(99M) = INITIAL vALUES 0F POHE PHEbbUHE ULTb = ULTIMATE PRIMARY SETTLLMENT UNDER TUIAL LUAD IIN.) HM] = INITIAL THICKNtbS OF LAYhH (IN.) I REA” 30 LIN FORMAT (F10.3) IEIEN.EQ¢1.0)300~WU PEN) 29NCV9NH.N[“IOIOCVIQUAMIQUAMZQGAMJghAMl-T FdRMATU+IboSF1flo3I READQQHI9H£9H39HHOCVC FORMAI(SF10.3) M I: 1 RfiAH 5. (PILoV)oL=1~9) FORMAI(9F8.Z) READ bgoULTScHNl FORMAI(ZF10¢0) DETLHMlNE NU. UF INCHEMENTS FUN SILP FUdCTlUN ULTERMINLU dY THr VALUES 0F CVoDToANU H ' NXDT = (4*NCV9NDT*96)/(1000*NH*NH) X01 = NX'UT HN:NH Y = GAM18H1*6AM2*fid+bAM3*HJ Z = bAM4*H4 X = Y/XDT SET HUUNDAHY PURE PHESbURLb = 0.00 FOR ALL TIMCS DO I N = 10200 P(10N) = 0.00 P(99N) = 0.30 Tp(1¢4) = 0.00 Tp(vqm) = 0.09 CON I le‘i O'DCC (VF/(TO (3006‘. 0000 0000 10 12 11 13 ”5. CALCULATL PURE HRt550HES GENERATLU HY UNIT INCHLASLs IN 51L? LUAH (LINEAR LOADINUI FOR EACH TIMt INCHEMENT LXDT = anT-l Do'o K = loLXDT 0039 L = 298 P( 9K+l) = PIL-K)*Z./3.+IP((L*l)9K)9P((L-I)9K))*l./6.+I.UU CO'TINUE CONTINUE CALCULATE ACTUAL I"IN-(L PRESSURtb ULNEHATLU AT END OF LINEAR LUAUINH ( 3N PSF ) DO€10 L 3 I99 PPIL) = x»v(t.qur) CONTINUE CALCULATE PERCENT CONSOLIDATION UNDdH THE tXIbIING APPLIED STRLSS FOR THE LINEAR LOADING (USINb THAPEZUIUAL RULE) suk = 0.00 XT' = 0000 00111 K = I9NKUT XII: xT+I.00 DOQIZ L = 198 B # ((2.*AT)-P(Lofi)-P((L+I)oK))/(lb.0*xT) SUM = 5UM+H CONTINUE UIKK) = 5UM*IOU.O SUM = 0.00 CONTINUE SE” INITIAL VALUE: OF PORE PktbSURE FUR SURChARGE INCREMENTAL LOADING. HERE L (UH TP(L91)) CUULD Ht MADE EQUAL TU FIELD VALULS 00:13 L = 298 TPKLol) = PP(L)9£ CONTINUE CALCULATE PURE DRLSSURES9 PERCENT CONSOLIDATION. AFTER SUHCHARCL APPLICATION J=I-I DO 13 K: 10.] DO 17 L = 298 TOIL9K+l)-= TPIL9R)*Zo/3o+(TP((L*1)9K)*TP((L‘I)9K))*l./6o CONTINUE CONTINUE DSUM = 000 00 20 K 3 I91 00 81 L z 199 ' D = ((Y+Z)*8.-TD(L.n)-TD((L+I)on))/¢Io.d*(¥+/)I DSUM = DSUIVHD :06 PI CONTINUE 026K) = UbUM*lCO. DSJM = 0.UO go CONTINUE TIl) = 0.00 TM1(1)=0.0 TM2(1)=0.00 DO 30 N = 2.200 TIN) = T(N-l)+1./96. TMl(N)=(T(N)*HN*HN)/(4.0*CV1*144U.) 30 CONTINUE DO 29 N=291 H:HNI-(UZ(N)+U2(N-l))/&UO.*ULT5 TM3(N)=(T(N)*H*H)/I4.0*CVZ*I4QU.) '29 CONTINUE I PRINT .NIT VALUES PRIIfNT 399NXUT9CV19NH9X9Y9Z 39 FORMAT(*1*9*NXUT = “91392X9*CV1 = *9F5.391K9*SU. IN./MIN.*92X9*NH I: “91391K9*IN.*92K9*X = *9F5.291A9*PbF/INCHEMENI*9ZA9*Y = *oFo.lol 2X9”P5F(LINFAR STHL551*92A9*Z = *9F5.191K9*P5F(bURCHAHht)*1 PRINT 31 31'FORMAT(*wfi*-%3A-*V0Hr ““H:SbUNt59 FmiunuuT LUH50LJIHXTIUN9 Inn; [0 LINE IAQ.APPL1LH 5TH:S5*) PRINT 33 33 FORMAT(“0*-18X9*r‘i='0*95K9*r‘1/.‘3*9b)\9*H/4*95K9*31‘1/6‘89‘9X91’H/2995X9 1*5H/8*94X9*3H/4*99K987H/8*95X9*H*9HX9*U*97A9*TIME9DAYS*) DO 100 K = 19NM)T - PRINT JS9K9T(K)9IP(L9K)9L = 199)9U1(K)9IM1(K) 35 FORMAT(*U*9I391X9*T = *9F7.599FH.29F8.19F8.1) 100 CONTINUE PRINT ‘919IPP(L)9L = 19919UIINXUT) 41 FORM4T(*0”9*PP I IN 95F 1*91X910F8ol) PRINT 809CV8 80 FORMAT(*O*oISxo*PUHL pHESbUHL59 PERCENT CUNbULIDATIUNo nut In SUHC IHARUE AN') LINEAR LUAU*9‘5X9*CV6 = “91.5.391X9*S(Jo IN. PER MINE”) PRINT 33 DOélOl K = 191 .PRINT HS9K9T(K)9(TP(L9K)9L = 19919UZIK19TMKIK) 45 FORMAT(*0*9I391X9*I = *9F’ob9916009F8o19F8011 101 CONTINUE GO'TU 50 300 CONTINUE END . _.- -... .-....'_......——m. ,. O'CCCCCDCOCOC “mnjlfiuD. .1 .n—..... 207 APPHMHIIH COMPUTER PROGRAM FOR THE SOLUTION TO THE EQUATIONS IN THE THEORY OF GIBSON AND L0 (1961) PROGRAM (71145051 (INPUT.-,IUT*’=JT) REAL LAMI DIMLNbIUN 5(9)) I = NU. LN? IIMI&»«)tblhtL\r%n< SKIILIWWJJT CUMPIHJAIIUN. 90 = APPLIED LUAU (951) A = PHIMHHY COWPKESBIHILITY (bu.Iu./Lu.) B = DECONUANY COWPRL551*H XT=~+.U/ 5. luib“ ( (A*H)/1§3)*‘J;y 12H/400 Canlefi -J p. CQLAQJLHTC }N)HE 4L