EPA-600/3-76-111
December 1976
Ecological Research Series
DESIGN CONSIDERATIONS FOR
PULP AND PAPER-MILL SLUDGE LANDFILLS
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
flhio 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal
species, and materials. Problems are assessed for their long- and short-term
influences. Investigations include formation, transport, and pathway studies to
determine the fate of pollutants and their effects. This work provides the technical
basis for setting standards to minimize undesirable changes in living organisms
in the aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/3-76-111
December 19?6
DESIGN CONSIDERATIONS FOR PULP AND
PAPER-MILL SLUDGE LANDFILLS
by
Richard H. Ledbetter
U.S. Army Engineer Waterways Experiment Station
Vicksburg, Mississippi 39l8d
Interagency Agreement No. EPA-IAG-D5-F657
Project Officer
Robert E. Landreth
Solid and Hazardous Waste Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio U5268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research Lab-
oratory, U. S. Environmental Protection Agency, and. approved, for publication.
Approval does not signify that the contents necessarily reflect the views and
policies of the U. S. Environments1 Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or recommendation
for use.
11
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FOREWORD
The Environmental Protection Agency (EPA) was created because of
increasing public and government concern about the dangers of pollution to
the health and welfare of the American people. Noxious air, foul water, and
spoiled land are tragic testimony to the deterioration of our natural environ-
ment. The complexity of that environment and the interplay between its com-
ponents require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solution
and it involves defining the problem, measuring its impact, and searching for
solutions. The Municipal Environmental Research Laboratory develops new and
improved technology and systems for the prevention, treatment, and management
of wastewater and solid and hazardous waste pollution discharges from munici-
pal and community sources, for the preservation and treatment of public drink-
ing water supplies and to minimize the adverse economic, social, health, and
aesthetic effects of pollution. This publication is one of the products of
that research, a most vital communication's link between the researcher and
the user community.
This report is a result of research supported by the EPA to obtain
engineering information essential to the design of environmentally acceptable
paper-mill sludge landfills.
Francis T. Mayo, Director
Municipal Environmental Research
Laboratory
in
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ABSTRACT
This report presents useful considerations for the engineering design and
control of pulp and paper-mill sludge disposal landfills. Engineering design
will allow more efficient use, thereby contributing to economic and environ-
mental benefits. To form the basis for engineering design of sludge material,
the methodologies and theories of soil mechanics were applied. The methodo-
logies should be applicable to most compositions of sludge materials. Some
sludge materials may have peculiarities associated with testing, field work-
ability, and behavior. However, from accumxilated experiences of applying the
procedures of this manual, the manual can be adjusted and expanded.
This report is specifically written for pulp and paper-mill personnel of
technical background, but with little or no exposure to the soil mechanics
discipline. The procedures are such that these individuals can rationally
approach a landfill operation to attain efficiency and optimization. This
report does not present a rigorous treatment or analysis of sludge material,
but it does give the above-mentioned individuals the procedures for determin-
ing good approximations of sludge behavior. Individuals interested in more
rigorous and theoretical analysis of sludge behavior should consult the list
of references.
This report is submitted in fulfillment of Interagency Agreement No.
EPA-IAG-D5-F657 between the U. S. Environmental Protection Agency, Municipal
Environmental Research Laboratory, Solid and Hazardous Waste Research Division
(EPA, MERL, SHWRD), and the U. S. Army Engineer Waterways Experiment Station
(WES). Work for this report was conducted during the period January 1975 to
January 1976.
This project was conducted by personnel of the Soils and Pavements Labora-
tory (S&PL), WES, under the general supervision of Mr. James P. Sale, Chief of
S&PL. Mr. Richard H. Ledbetter prepared this report.
Directors of WES during the preparation and publication of this report
were BG E. D. Peixotto, CE, and COL G, Ho Hilt, CE. Technical Director was
Mr. F. R. Brown.
IV
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CONTENTS
Paee
Foreword iii
Abstract iv
List of Figures and Plates vi
List of Tables viii
List of Abbreviations and Symbols ix
Acknowledgements xiv
I The Nature and Disposal of Paper Industry Primary Sludges 1
II Retaining Structures 13
III Consolidation, Settlement, and Slope Stability 19
IV Field Experimental Example 27
V References 38
Figures 1-2^
Tables 1-8
Plate 1
A Metric Conversion Table 71
B Testing Procedures for Sludge Properties 72
Figures B-l through B-l8
Tables B-l and B-2
Plates B-l through B-13
v
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LIST OF FIGURES AND PLATES
Number Page
1 Variability of sludge properties ................ Hi
2 Relationship of sludge dewater ability to ash content ...... k2
3 Solids content versus ash content ............... ^3
h Mass of leachate constituents ................. kh
5 Dike and sludge cross section ................. ^5
6 Plan for landfill ....................... h6
7 Sludge landfill construction steps ............... ^7
8 Weight and volume relationships . . .............. U8
9 Compressed sample ....................... 1±9
10 Load-depth diagram ....................... 50
11 Load increment added to a sludge layer ............. 51
12 Time factors for consolidation analysis ............ 52
13 Nomograph for consolidation with vertical drainage ....... 53
lU Time factors for consolidation analysis with gradual
load application ....................... 5^
15 Slope analysis ......................... 55
l6 Correction factor for converting vane shear strengths to
field shear strengths .................... 56
17 Experimental landfill, plan view ................ 57
18 Typical cross section of experimental landfill ......... 58
19 Consolidation characteristics of sample sludge ......... 59
20 Comparison of predicted and measured time-settlement curves,
lower sludge layer ...................... 60
21 Comparison of actual and predicted time-settlement curves,
upper sludge layer ...................... 6l
22 Experimental landfill vane shear strength immediately before
slope excavation ....................... 62
23 Cut slope in experimental sludge landfill ........... 63
2U Cross section of top sludge layer for stability analysis .... 6k
B-l Determining the weight of a sludge specimen submerged
in water ........................... 109
vi
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Number Page
B-2 Evacuating air from samples in determination of specific
gravity 109
B-3 Typical calibration curve of volumetric flask 110
B-U Stages of consistency „ 110
B-5 Liquid limit device Ill
B-6 Details of liquid limit device ..... ..... 112
B-T Grooving liquid limit specimen ...... . . 113
B-8 Closed liquid limit groove . ...... 113
B-9 Plastic limit determination 113
B-10 Crumbling of threads at plastic limit . 113
B-ll Apparatus for determining the volume of dry sludge pat of
shrinkage limit test 11^
B-12 Typical consolidometer (fixed-ring type) vith falling-head
device for permeability test 115
B-13 Typical retainer ring ...... Il6
B-lH Time-consolidation curve 117
B-15 Square root of time-consolidation curve 118
B-l6 Determination of height of capillary rise 119
B-17 Void ratio-pressure curve 120.
B-l8 Vane shear test equipment . 121
1 Settlement-Time Plot 70
B-l Water Content - General 12U
B-2 Unit Weights (Volumetric Method) 125
B-3 Unit Weights (Displacement Method) 126
B-l* Specific Gravity Tests 127
B-5 Liquid and Plastic Limit Tests 128
B-6 Shrinkage Limit Test 129
B-7 Consolidation Test (Specimen Data) 130
B-8 Falling-Head Permeability Test with Consolidometer 131
B-9 Consolidation Test (Time-Consolidation Data) 132
B-10 Consolidation Test - Time Curves 133
B-ll Dial Reading Versus Time-Data for Each Load Increment 13!*
B-12 Consolidation Test (Computation of Void Ratios) 135
B-13 Consolidation Test Report 136
VII
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LIST OF TABLES
Number Page
1 Primary Sludge Production Associated with
Paper Manufacturing 65
2 "Normal" Sludge Composition 65
3 Physical Characteristics of Sludges Originating in High Ash
Sludge Landfills 66
k Fibre Classification for Selected High Ash Sludges 66
5 Analysis of Leachate Quality 67
6 Trace Elements Contained in Paper-Mill Primary Sludge 68
7 Leachate Attenuation Properties of Soils 68
8 Physical Properties of Paper-Mill Sludge 69
B-l Relative Density of Water and Correction Factor K for
Various Temperatures 122
B-2 Correction Factor RT for Viscosity of Water at Various
Temperatures 123
VI11
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LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
BOD
°C
cm
3
cm
COD
deg
EPA
ft
in.
2
kg/cm'
In. /min
2
lb/ft
rb/ft3
Ib/ton
LL
mg
mg/£
mm
MTU
pcf
PI
PL
psf
sec /g
2
SL
T/ft
T/m2
ymho/cm
biochemical oxygen demand
degrees Centigrade
centimetres
cubic centimetres
chemical oxygen demand
degrees
Environmental Protection Agency
feet
inches
square inches per minute
kilograms per square centimetre
pounds per square foot
pounds per cubic foot
pounds per ton
liquid limit
milligrams
milligrams per litre
millimetres
turbidity
pounds per cubic foot
plasticity index
plastic limit
pounds per square foot
seconds squared, per gram
shrinkage limit
tons per square foot
tons per square metre
micromhos per centimetre
IX
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SYMBOLS
A — cross-sectional area
A — ash content
c
a — area
C — volumetric change from a given water content w (usually the
liquid limit)
CaCo^ — calcium carhonate
Cd — cadmium.
Cr — chromium
Cu — copper
C — coefficient of secondary compression
C — compression index
C — coefficient of consolidation
v
D — diameter
D — initial dial reading
e — void ratio
e_ — void ratio after test
e — initial void ratio existing at P'
o o
F — safety factor
Fe — iron
G — specific gravity of solids
S
H — height
H — length of longest vertical path for drainage of water
Hg — mercury
H — height of specimen at end of test = H - AH , in., where AH
is the net change in height of specimen
H. — average height of the specimen for the load increment
H — height of solids
s
H — total thickness of sludge layer
H — height of voids
H — final height of water
wi
H — original height of water
wo
h — height
h — height of capillary rise
h, — height of tailwater
x
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20
Wi
0
c
P
Pb
P'
P'
lower
P'
upper
P'
o
R
R
S
S
U
s
T
T
t
t,
max
pri
sec
initial height of water in standpipe
final height of water in standpipe
hydraulic gradient
correction factor based on density of water at 20°C
coefficient of permeability
coefficient of permeability at 20°C
height
linear shrinkage
magnesium
individual layers of different sludge within a single layer of
sludge
nickel
organic content
load pressure or stress
lead
effective pressure or stress
effective pressure or stress, lower layer
effective pressure or stress, upper layer
average initial effective stress within sludge layer
total initial stress
load pressure
rate of fluid discharge
shrinkage ratio
correction factor for viscosity of water at 20°C
degree of saturation
initial degree of saturation
undrained shear strength
solids content
dimensionless time factor
maximum torque
time
final time
end of construction time
time for primary consolidation
time for secondary consolidation
XI
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"total
U
u
V
Vf
V
c
W
W
c
W
w
W.
TDW
w
•fc
w.
"bws
w
Zn
z
a
m
Yw
AD
AH
AH
AH
I
AH
AH
AH
pri
sec
total
pri
lower
AH
pri
upper
AH
sec
lower
AH
sec
upper
AH
total
time for total settlement
percent of primary consolidation
pore hydrostatic pressure
volume
volume of landfill
volume of solids
total weight
weight of dry solids
weight of water
weight of flask plus water
weight of water in specimen after test
original height of water
weight of flask plus water plus solids
water content
zinc
depth
angle
slope angle
dry unit weight
wet unit weight
unit weight of water
change in height of specimen
change in height
decrease in specimen height over log cycle
primary settlement
secondary settlement
total settlement
primary settlement, lower layer
primary settlement * upper layer
secondary settlement, lower layer
secondary settlement, upper layer
total settlement, lower layer
lower
XII
-------
total
Ah
AP
AP
lower
AP
upper
AX, Ax
AV
upper
— total settlement, upper layer
--T corrected tailwater - h, + h
t c
— total load above sludge layer
— total load acting on the lower sludge layer
— total load acting on the upper sludge layer
— slice width
— change in volume
— angle of internal friction
Xlll
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ACKNOWLEDGEMENTS
Mr- Duane W. Marshall of the National Council of the Paper Industry for
Air and Stream Improvements, Inc., wrote Section I of this report. Field and
laboratory investigations of sludge material were conducted by Dr. 0. B.
Andersland during the period 1970-197^-
xiv
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SECTION I
THE NATURE AND DISPOSAL OF PAPER
INDUSTRY PRIMARY SLUDGES
INTRODUCTION
Associated with the application of conventional and advanced wastewater
treatment technologies, but often obscured by the benefits to receiving-stream
quality, is the accumulation of vaste constitutents into either a highly con-
centrated solution or aqueous suspension of residual solids commonly described
as sludge. Where those concentrated residuals have no potential for reuse or
by-product development, they must be further processed for ultimate disposal
to the environment. In doing so, the land as a practical matter represents
the ultimate repository in all but those instances where (a) the incineration
of organic components and subsequent discharge of combustion products to the
atmosphere constitutes a viable alternative or (b) the limited opportunity of
ocean disposal exists.
For many years, the disposal of wastewater treatment sludges has been re-
garded as a problem as great or greater than that of treating the waste it-
self (l). Furthermore, the generation of large quantities of hydrous residues
associated with the increasing degrees of waste treatment mandated by existing
regulation has perpetuated, if not amplified, the problem. Though the dewa-
tering and disposal of these residual solids are widely recognized to repre-
sent a significant fraction of the costs for wastewater treatment, Dick (2)
justifiably concludes that "the attention which has been given to sludge
treatment and disposal in the past, as compared to processes for initial re-
moval of pollutants, has been more nearly proportional to the relative volume
of sludge than to the relative cost of sludge disposal." Moreover, if over-
all control strategies are to result in minimal net environmental impact,
issues relevant to the accumulation and subsequent management of those resid-
ual solids must be thoroughly weighed in the development of comprehensive en-
vironmental regulation sensitive to intermedia effects. Included among those
issues are the protection and/or optimum utilization of land resources.
Among the solids that are accumulated in the treatment of wastewaters of
pulp and paper origin are those lost from the papermaking process and subse-
quently separated during primary clarification. These solids are composed of
fibre, filler, and coating clays, and in the case of those manufacturing
categories in which wastepaper constitutes a significant portion of the prod-
uct furnish, considerable quantities of impurities. Information compiled by
Miner (3) and shown in Table 1 indicates that solids losses from most cate-
gories of paper manufacture represent from 2 to U percent of production. Ex-
ceptions include waste-paperboard where the nature of the paper grade produced
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at nearly half of the installations surveyed permitted return of primary
sludge to the production process. The relatively large losses from deinking
operations are associated with removal of inks and other nonfibrous materials
from a wastepaper furnish. Recently reported results (U) of a survey of pulp
and paper mills indicated that 78 percent of the sludge generated at those
mills responding to the survey was disposed of either in or on the land.
Thus, land disposal remains the largest single method of sludge management
practiced in the pulp and paper industry.
Emerging land-use patterns and the decreasing availability of land con-
sidered acceptable for landfill pose a potential constraint to continued land
disposal practice in many areas. In those cases where the fibre or organic
content of the primary sludge is at least 50 percent, incineration presents a
feasible alternative. In fact, 15 percent of the sludge generated at mills
responding in the above-cited survey was disposed of by incineration. How-
ever, costs associated with separate incineration of sludges in quantities
commonly found at mills have largely limited the practice to those integrated
operations with wood fuel boilers.
In addition, the composition of sludges generated at many installations
further restricts the practice of incineration. Data reported by Gillespie
et al. (5) and shown in Table 2 indicate that sludges with ash contents ex-
ceeding 50 percent are commonly associated principally with the manufacture of
(a) board, (b) deinked pulp and paper, and (c) integrated and nonintegrated
fine papers. Furthermore, the economic impetus for greater fibre recovery and
utilization will likely result in sludges of progressively greater inorganic
content. Incineration is not a realistic alternative for those sludges
because of (a) their relatively low organic content, (b) the attendant low
moisture requirements necessary for self-supporting combustion, and (c) the
inevitable necessity for further land disposal of the predominant inorganic
fraction. Barring by-product recovery opportunities, land disposal remains
the only feasible alternative in that situation.
Of the mills which must deal with the disposal of high ash sludges, more
than 100 are located in or adjacent to metropolitan areas where land available
for solid waste disposal is limited. As a consequence, it will be incumbent
upon those mills, and probably others as well, to optimize landfill disposal
by the application of sound engineering principles to all stages of site
selection, design, operation, and ultimate land use. Factors warranting con-
sideration in such an approach would include the significance of sludge compo-
sition to its engineering behavior, as well as the environmental implication
involved.
The variability of sludge composition from site to site and the complex
interaction of those sludge constituents known to influence landfill behavior
require the assessment of a sludge's engineering characteristics by means of
functional tests known to be of significance to the rational design of a land-
fill to attain some given objective, inclusive of a given rate or degree of
consolidation, associated rate of leachate discharge, or ultimate land use.
It was in this context that the National Council of the Paper Industry for Air
and Stream Improvement sponsored initial efforts by Andersland (6,7) aimed at
documenting the applicability of traditional soil mechanics techniques for
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relating basic engineering properties of dewatered sludges, specifically shear
strength, permeability, and consolidation. The utility of those tests for
prediction of actual landfill behavior has been verified for one composition
of sludge in subsequent work conducted by Andersland and sponsored by the
Environmental Protection Agency (EPA) Division of Solid Waste Research (8,9).
In illustrating the principles and knowledge previously gained, the remaining
sections of this manual are advanced in the following context:
a. This report identifies useful consideration in the engineering design
and control of pulp and paper-mill sludge disposal landfills. Engi-
neering design will allow more efficient use, thereby contributing
to economic and environmental benefits. The pulp and paper industry
will benefit economically by being able to dispose of larger quantities
of sludge in a given landfill than past practices permitted. Also,
after completion of landfills, they could be used for recreational
purposes benefitting the public, or as real estate investments bene-
fiting the pulp and paper industry.
b. Andersland's investigations were carried to completion by field ex-
periment for only one composition of sludge material. However, the
methodology should be applicable to most other sludge compositions.
Sludge material other than that used by Andersland may have peculiari-
ties associated with testing, field workability, and behavior. How-
ever, from accumulated experience of applying the tests and procedures
of this report, the report can be adjusted and expanded. In addition
to landfill design considerations, the test procedures can be used as
a measure of the effectiveness of dewatering processes. The example
material and procedures of this report are based on Andersland's
investigations.
c. This report is written specifically for pulp and paper-mill personnel
of technical background, but with little or no exposure to the soil
mechanics discipline. The procedures are such that the above mentioned
individuals can rationally approach a landfill operation to attain
efficiency and optimization. This report does not present a rigorous
treatment or analysis of sludge material, but it does give the above-
mentioned individuals the procedures for determining good approxima-
tions of sludge behavior. Individuals interested in more rigorous
and theoretical analysis of sludge behavior should consult the list
of references.
SLUDGE COMPOSITION, ITS IMPACT ON ENGINEERING BEHAVIOR
Paper industry primary sludges are commonly characterized by the relative
proportion of either the combustible or fixed solids (10) comprising the sludge
mass. However, a characteristic of equal prominence from the perspective of
solids handling and disposal is the water content, which may represent 90 to
98 percent of the sludge mass, as illustrated in Table 2.
Water Relationships
Gehm (11) has classified the water associated with paper-mill sludges as
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either free, interstitial, or water of imbibition. The free water is con-
sidered readily separable and constitutes but a small fraction of a thickened
sludge. Water of imbibition characterizes water chemically bound or physi-
cally trapped within the lattice structure of colloidal sols. It cannot be
removed by mechanical means and, as such, would pose a limiting condition to
the capabilities of such dewatering technology,, However, the water of imbibi-
tion represented less than 2 percent of the water associated with cellulesic
residues evaluated by Zettlemoyer (12) in his study of the surface properties
of hydrogels resulting from treatment of pulp and paper-mill effluents. As a
consequence, such a small proportion of water of imbibition does not charac-
terize the dewatering properties of paper-mill sludges. Rather, Zettlemoyer
concludes that interstitial water held in the pores of the system by surface
energy phenomena amounts to greater than 90 percent of the water associated
with a thickened sludge.
The rate and extent of interstitial water separation are best defined in
terms of the composition and nature of the sludge solids.
Solids Composition
Noncombustible Fraction—
The noncombustible fraction consists primarily of such filler materials as
kaolin clays and titanium dioxide, with possible quantities of silicates and
carbonates. Their composition and physical properties, as well as other pig-
ments finding specialized application in paper manufacturing, are detailed
elsewhere (13). The most striking characteristic of those solids from the
perspective of sludge dewatering lies in their fine particle size, predomi-
nantly smaller than 2y.
In addition to variation among various production categories, sludge ash
content is observed to have considerable daily variation at individual instal-
lations, dependent upon the grade manufactured and performance of fibre re-
covery systems. The variation over a UO-day period at a mill manufacturing
fine papers is shown in Figure 1, along with the corresponding variation in
sludge filterability.
Comparison of those variables indicates that the impact of the inert com-
ponent alone is insufficient to explain the variation in sludge filterability.
Organic Constituents--
The organic fraction may consist of fibre and such colloidal components as
highly hydrated wood dust, fibre debris, ray cells, starches, dextrines,
resins, and protein. Though but a small proportion of the sludge mass, the
colloidal components exert a disproportionate effect upon the filtration
properties of paper-mill sludges.
The fibrillar structure of cellulosic components and the associated size
of interstices impart a capacity for the retention of water by capillary
forces. Fibre length, or otherwise particle size, of cellulosic constituents
poses a further determinant of the dewatering characteristics. The separation
of water is restricted by the size of passages available for flow which in
turn is a function of particle size and particle size distribution. The
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relative importance of various size fractions has been established in studies
of the relationship between the constitution and the dewatering properties of
hydrous sludges (lU). Fractions smaller than 200 mesh were observed to be
capable of much greater compaction with the resulting smaller pore sizes
yielding greater resistance to flow and greater retention of water by capil-
lary action. In contrast, the fraction greater than 60 mesh was relatively
easily dewatered. Chemical composition is of additional influence due to the
potential presence of swellable polysaccharides among the finer size fractions.
They represent the principal constituent capable of binding water at the
molecular level (water of imbibition). More importantly, however, the deform-
ability and conformability of such particles dictate the degree to which com-
paction can result in a corresponding sealing of the sludge interstices.
Observed Behavior
The physical characteristics shown in Table 3 were compiled in the course
of studying core samples extracted from existing high ash sludge land-
fills (15)- The deposits, ranging in age from 3 months to 20 years, showed
considerable vertical stratification reflective of changes in paper grades
produced and fibre recovery practices. The presence of long fibre (greater
than 100 mesh) in quantities constituting approximately 20 percent of the
sludge mass may be considered representative. In most cases, the fraction
passing the 200-mesh sieve exceeds the ash content and is indicative of the
extent to which troublesome cellulosic fines are present. A more detailed
classification of fibrous components greater than 100 mesh for several mills
generating high ash sludges is shown in Table U (3). The data would suggest
that size distribution is specific to individual mills, though the fibre pres-
ent for the mills shown is predominantly smaller than 38 mesh.
The interacting effects of particle size, composition, and solids consis-
tency on sludge drainage can be best assessed in terms of their influence on
sludge porosity. The fine particles common to both the organic and noncom-
bustible fractions exert a dominant physical effect upon sludge dewaterability.
The resistance of sludges to filtration is particularly sensitive to par-
ticle size and is substantially increased by the presence of fines. The sig-
nificant reduction in the proportion of voids inherent with particles of such
small size, as well as their lodging within the interstices of larger parti-
cles, constitutes an obstacle to the migration of water within the sludge mass.
In illustrating their impact, Gale (l6) projects that a ten-fold decrease in
effective particle size would result in a 100-fold decrease in filterability.
The predominance of fines in high ash sludges has been observed to impart
virtual impermeability to dewatered cakes. Studies with pulp suspensions (lU)
have demonstrated decreasing filterability as a consequence of successive ad-
dition of clay- In the course of successfully demonstrating the applicability
of geotechnical engineering tests and principles to high ash sludge landfill
behavior, Andersland (6) observed that sludge permeability progressively de-
teriorated as organic content was decreased from ^3 to 28 percent by removal
of long fibre. However, over that range of organic contents, sludge perme-
ability was also dramatically decreased by increases in cake consistency.
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This parallels observations with mechanical sludge de-watering that the bene-
ficial presence of fibre longer than 100 mesh was diminished as slurry con-
sistency was increased for those sludges high in colloidal content. Thus,
sludges become increasingly impermeable with progressive dewatering or consol-
idation. Andersland (7) also observed that higher sludge solids content re-
sults in a reduced rate of consolidation, thus requiring greater time to reach
ultimate settlement.
Recognizing the importance of sludge cake consistency, the distinction
needs to be made between the rate and extent that water can be expressed from
sludges. Notwithstanding their lower permeability, high ash sludges also
exhibit a reduced capacity for retention of water which is attributable to the
denser, nonporous structure of individual clay particles in contrast to
properties of organic components likely to be present. Laboratory study (IT)
documents the likelihood of greater filter cake consistencies being associated
with higher ash content sludges. Confirmation is seen in Figure 2 which
illustrates an increasing trend of cake consistency with greater ash content
observed for numerous installations employing either vacuum filtration or cen-
trifugation for the mechanical dewatering of primary sludges (3). A similar
observation was made by Mazzola (15) for sludge samples taken from various in-
depth landfills at nine installations, as shown in Figure 3. An associated
observation was that sludge moisture contents had changed very little with
time.
Another factor of importance to sludge permeability, but not inher-
ent with its composition, is the presence of minute gas bubbles incorporated
during dewatering or entrapped during placement of sludge in the landfill.
Andersland (6) concluded that undissolved gas in the sludge pore fluid was
responsible for reduced permeability, and, as a result, a certain hydraulic
gradient was necessary to induce flow at low back pressures. Though the
effect of gas bubbles on permeability persisted up to back pressures ranging
from 60 to 120 ft (see Appendix A, Metric Conversion Table) of water, the mag-
nitude of the threshold gradient decreased with an increase in back pressure.
As an example, it was reported that for a secondary fibre mill sludge and zero
back pressure, this gradient was as high as 1177. This is of practical sig-
nificance to the drainage and subsequent consolidation of sludge since hydrau-
lic gradients in field embankments can be less than one.
Summary
The separation of water from paper industry primary sludges is predomi-
nantly a function 'of those factors which determine the size of interstices
available for fluid flow. As a further analogy, Andersland (6) has cited that
the permeability of pulp and paper-mill sludges is dependent upon the same
variables as those for soils. These reduce to (a) particle size, (b) particle
size distribution, and (c) the deformability or conformability of sludge fines
as a consequence of chemical composition.
The capacity, then, for sludge solids to dewater or consolidate in land-
fills will decrease as the relative proportions of ash and organic fines
are increased. Permeabilities are further deteriorated with progressive
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increase in cake consistencies and the presence of entrapped gases within the
sludge interstices.
ENVIRONMENTAL CONSIDERATIONS
Implicit with the optimization of landfill disposal sites by the applica-
tion of sound engineering principles is consideration of the overall impact
upon the environment. As a consequence, the potential for intrusion into the
groundwater of constituents associated with the sludge and its subsequent de-
composition warrants attention. If leachates on a case-by-case basis show a
potential, according to the proposed standards of the Federal Water Pollution
Act Amendments of 1972, for pollution of receiving waters whether ground or
surface, necessary actions should be taken in order to prevent contaminants
from reaching the receiving waters. The likehood of groundwater contamination
can be compacting the landfill bottom material to a permeability of less than
1.75 x 10"-^ cm per sec or by using a layer of impervious clay or synthetic
material. In addition, leachates will have to be collected.
Leachate Composition
Leachates originating within landfills may be characterized as being high
in dissolved solids and chemical oxygen demand (COD) and biochemical oxygen
demand (BOD). Data contained in Table 5 illustrate leachate composition ob-
served in studies of an experimental high ash sludge landfill in West Carroll-
ton, Ohio (8).
Leachate constituents present in the greatest quantities are dissolved
organic matter, mineral salts, and those contributing to specific conductance,
and alkalinity. Alkalinity was consistently greater than total hardness,
indicating that hardness was entirely of carbonate origin. Consistent with the
buffering capacity associated with leachate alkalinity, pH varied over the nar-
row range of 7.5 to 7.8. Such a pH is uncharacteristic of domestic landfill
leachates whose acidic nature and lower pH values tend to reduce exchange capa-
cities of renovating soils (18). Specific conductance values observed in
this study do exceed the single value of 3000 ymho/cm cited by Emrich (19) in
illustrating that parameter as an example of persistence for as long as
20 years of pollution potential of leachate emanating from landfills of
municipal refuse. Concentrations of BOD, hardness, and dissolved solids,
reported for leachates originating from landfills of domestic refuse, span a
wide range and encompass the values observed in this study (18, 20, 21, 22).
A ratio for BOD to COD of 0.68 was also observed over the duration of the
2-year study. With the exception cited above, suspended solids did not exceed
160 mg/£, nor was turbidity in excess of 56 MTU. Considering the origin of
the fill material utilized for this evaluation, it is not surprising that
leachates would be nearly void of organic nitrogen and phosphorus. In a num-
ber of instances, concentrations of iron and chloride in Samples I through V
nominally exceeded the 0.7- and 181-mg/£ concentrations for those respective
constituents in the in situ sample, suggesting the possibility of some leach-
ing from the drainage beds or, perhaps, a decrease in those residuals by the
conclusion of the study. Concentrations of nitrogen and phosphorus, as well
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as chloride and sulfate, are significantly less than reportedly present in
domestic landfill leachates.
Whatever similarities might be suggested between leachate concentrations
typical of this study and domestic landfills, the significant differences in
the mass of constituents discharged is made apparent in Figure U. The high-
ash-sludge landfill constituent mass vas estimated assuming a hypothetical
leachate strength as great as that represented by the dry weather concentra-
tions for the entire volume displaced. Representative domestic refuse land-
fill masses were estimated based upon data reported by Merz (21}. Based upon
those estimates, the mass of BOD per unit weight of dry solids associated with
the high ash sludge was but 7 percent of that reported for domestic refuse;
alkalinity approximated UO percent.
These distinctions between landfills containing paper-mill sludge and
municipal refuse are advanced only to illustrate that the arbitrary applica-
tion of regulations developed for municipal sanitary landfills is not war-
ranted. Rather, implementation of regulation should reflect what is known of
sludge composition and associated leachate characteristics.
The presence of heavy metals and other elements considered hazardous to
public health is not characteristic of paper-mill sludges. With the possible
exception of zinc, those compounds are not inherent in the paper manufacturing
process and originate as trace components in raw materials. As a result, they
appear in only trace amounts in mill sludges, as shown for several mills in
Table 6. The use of zinc compounds as brightening agents for groundwood pulps
and clays accounts for its occasional presence in more significant concentra-
tions. However, the increasing substitution of other brightening compounds
will progressively diminish the occurrences of zinc in paper-mill sludges.
The alteration of the composition and properties of a fill's organic com-
ponents by microbial attack could result in the loss to the leachate of inter-
mediate metabolic products. In the case of paper-mill sludge landfills, the
anaerobic environment, as well as the absence of such supplemental nutrients
as nitrogen and phosphorus, significantly retards the degradation of the
fibrous sludge constituents. From a survey of literature data on nitrogen and
phosphorous requirements for cellulose degradation, Springer (23) estimated
that from 2 to 60 mg of nitrogen and from 1 to 10 mg of phosphorus per gram of
cellulose were required for cellulose decomposition. Imshenetsky (2U) has re-
ported that decomposition of cellulose becomes essentially inactive when
available nitrogen becomes less than 1.2 percent.
Paper products have been found virtually unchanged in landfills that had
been completed for 15 to 25 years. Mazzola's observations of high-ash-sludge
landfills further substantiate the slow rate of decomposition. On the basis
of photomicrographs of core samples, fibre contained in samples estimated to
be 10 to 12 years old was nearly indistinguishable from that contained in a
fresh sample.
The practical consequence of such retarded degradation is that further
leachate contamination resulting from fill decomposition would be moderated
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over a protracted length of time. In addition, the formation and migration of
gases associated with decomposition would be minimized.
Attenuation by Soil Percolation
The capacity of soil percolation to rapidly decrease the concentration of
potential pollutants has been documented in the literature, as well as by ly-
simeter work conducted in conjunction with the West Carrollton landfill
study (9)- Results summarized in Table 7 show the proportion of the applied
constituent mass retained within the 3-ft soil columns over an approximate
5-month application period at rates approximating field conditions. Soil
varieties evaluated included sand, clay, and organic loam. The last was in-
vestigated under aerobic and anaerobic conditions.
All soil columns exhibited excellent organic removal, though sand appeared
slightly less efficient. In all cases, an acclimation period was necessary
before highest removal efficiencies were obtained. None of the 3-ft soil col-
umns gave any indication that organic removal capacity was becoming exhausted
over the 160-day observation period. Anaerobic conditions were observed to be
less efficient than aerobic conditions for organic removal. All soil columns
showed some capacity to attenuate inorganic constituents. However, with the
exception of clay, all columns demonstrated a decreasing capacity to do so
over the duration of the study.
In all, it was the conclusion of that study that passage of leachate
through a minimal depth of natural soil would render the percolate innocuous.
In addition, the relative impermeability of the high ash sludge and the de-
creasing rate of leachate flow associated with fill consolidation exert a
moderating effect upon the quantity of leachate percolating to the groundwater.
Impermeability would further minimize rainfall infiltration of the landfill as
a potential leachate source. However, in such a case, caution would have to
be exercised to prevent runoff and subsequent drainage into surface waters.
Summary
Substances most likely to prove objectionable should high-ash-sludge
leachates become a part of the groundwater would include dissolved organic
matter, mineral salts, and hardness. Concentrations were within the broad
range of those reported for leachates originating in landfills of municipal
refuse. However, on a mass basis, leachate constituents associated with the
high-ash sludge were significantly less. (Moreover, sludge composition is such
as not to constitute a hazard to public health.)
In consideration of alternate approaches to protection of groundwater
sources from the intrusion of leachate constitutents, the demonstrated capac-
ity of soil percolation to effect a degree of renovation equivalent or supe-
rior to conventional treatment technology merits attention. As such, a paral-
lel exists with the land application of wastewaters, an approach which has re-
ceived national focus as an effluent management strategy. The suitability of
percolation is advanced contingent upon the existence or provision of a suit-
able soil of sufficient depth and distribution prior to groundwater utiliza-
tion to provide the necessary renovations at anticipated hydrologic conditions,
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The nature of high-ash sludges is such that inherent impermeability
minimizes leachate formation. The opportunity also exists for minimizing the
quantity of leachate to be renovated by further sludge dewatering consistent
with technological capability. The options available are sufficient to justify
any selection on a case-by-case basis as opposed to a single universal approach
to groundwater protection from landfill leachate intrusion.
CURRENT LANDFILL PRACTICE
Landfill practice can be expected to receive increasing attention of
regulatory agencies. In addition, overall solid waste management will likely
constitute a significant aspect of activities carried out under the regional
planning provisions of the Federal Water Pollution Act Amendments of 1972.
Commonly encountered requirements for the regulation of industrial process
landfills have been previously outlined by McKeown (A). McKeown further stated
that restrictions on the siting of landfills are largely oriented toward mini-
mizing the potential for leachate contamination of ground and surface waters,
as well as avoiding public nuisance. Such provisions, for example, manifest
themselves as requirements that:
a. The disposal site be a minimum of 2 to 5 ft. above groundwater.
b. The site be 50 ft. above a floodplain.
c. The site be a minimum of 1 mile from a public well.
d. The site be at least 300 ft. from watercourse.
e. All subsurface conduits be removed (i.e., culverts, gas and water
lines, etc .) .
f. The minimum distance to a highway be 1000 ft.
g. The nearest property line be 20 ft. from the site.
A notable distinction between the operating requirements imposed upon
municipal sanitary landfills and those of paper-mill origin is the necessity
for daily application of cover material. In the former case, compaction and
daily cover is necessary for:
a. Controlling the breeding of vermin.
b. Discouraging the entrance of rodents.
c. Preventing scavengers from feeding upon the wastes.
d. Control of gas movement.
e. Retarding rainfall infiltration of the fill.
f. Prevention of fire.
10
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It is evident from the composition of and known behavior of paper-mill
sludges that such latter precautions are unnecessary. Moreover, their proper-
ties are such that they have an inherent ability to fulfill many of the func-
tions required of the cover material. Not only are paper-mill sludge landfills
normally exempted from daily cover requirements, the precedent exists for
their being utilized as a daily cover for sanitary landfills.
Prior to the issuance of a permit for operation of an industrial solid
waste disposal system, a number of states require that the entire waste
management plan be reviewed for conformity to sound engineering practice.
Examples of provisions for design and operation that have been advanced for
inclusion in plans requiring regulatory agency approval are as follows:
a. General: Map or aerial photograph of the area showing land use and
zoning adjacent to the proposed disposal operation. The map or aerial
photograph should show all homes, industrial buildings, wells, water-
courses, dry runs, rock outcroppings, and roads. General topography
should also be identified.
b. Geological Considerations: Geological examination of the proposed
area is a useful adjunct to siting. Soil borings of sufficient num-
ber and depth should be taken to provide a subsurface investigation
representative of the entire site. Such tests are made to determine
the porosity and permeability of the soil in the landfill area. Sites
with low permeability are usually preferred. General path and rate
of flow of groundwater flow should be estimated.
c. Groundwater Testing: Both the level and quality of groundwater are
determined using test wells or pits. Sampling to include seasonal
variation is suggested. (Test wells can later be used to check
groundwater quality after site is operative.) Wells are usually to
be placed upstream and downstream of the projected groundwater flow
pattern at varying levels.
d. Rivulet Diversion: The impact of the fill upon area drainage patterns
should be considered. Natural drainage paths may be rerouted, or in
some cases covered and protected from landfill runoff. Natural
springs may also require rerouting. Surface drainage from the com-
pleted fill should also be considered.
e. Development of a proposed plot plan of the site showing dimensions,
location and ground surface elevation of soil borings, original and
proposed final land contours, proposed trenching plan or original
fill face, existing and proposed drainage patterns, access roads and
any fencing.
(1) Fencing should be considered if site is near public roads or
population and open to easy access. Lighting should be considered,
especially if nighttime delivery is planned.
(2) Roads should be planned based upon the expected life of the site
and types and loadings of trucks and frequency of delivery. If
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traffic routes include public roads through populated areas, some
thought is usually given to scheduling vehicles to provide minimum
neighborhood disturbance, especially when steep grades are in-
volved. The potential for erosion and dust problems within the
landfill site warrant attention.
(3) Final Grade: Consideration should be given to planning for future
use of the land after the site has consolidated naturally.
f. Equipment and Operational Reqairements: Heavy duty dump trucks and
spreading equipment are necessary. The amount of sludge and size of
storage pads will dictate the type.3 and sizes of trucks to be used. A
number of mills store sludge for delivery during daylight hours.
Storage is usually upon a concrete apron protected from receiving ex-
cessive rainfall. Front-end loaders are used to clear the apron into
trucks during daylight. Storage volume should be designed to accumu-
late sludge during particularly inclement weather. Snow removal and
road clearance equipment are obvious requirements in cold climate.
g. Thought should also be given to development of such information as
sludge composition, moisture content, anticipated quantities, degrad-
ability, and potential leachate properties.
Implicit in fulfilling a number of the previously cited considerations is
a knowledge of the rate and extent of landfill consolidation and behavior.
12
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SECTION II
RETAINING STRUCTURES
The basic objective of engineering sludge disposal landfills is to com-
press (consolidate) and confine the material and stabilize its behavior. By
consolidating the material, its strength is increased many times and it be-
comes a stable solid that will stand as an embankment. The available landfill
volume will be increased by the difference between the volume of freshly
placed sludge and the amount of consolidation, and by the ability to construct
high mounds of consolidated material.
NEED FOR SLUDGE CONFINEMENT MfD SURCHARGE
In order to best achieve the objective, the sludge material must be con-
tained and physically consolidated. Temporary dikes are required to laterally
contain the material, and surcharge loads are required to induce consolidation
by forcing water from the material. Surcharge loads are necessary for two im-
portant reasons:
a. Sludge has a tendency to hold or retain water because of its composi-
tion and may be only slightly free-draining (6, 9, 15). Therefore,
surcharge loads are required to sufficiently increase the water pres-
sure internal to the sludge material such that the water will flow out
from the material. This dispersion of water will therefore allow the
material to consolidate to a lesser volume. The decrease of volume is
approximately equal to the volume of water dispelled.
b. Surcharge loads accelerate consolidation, thereby significantly de-
creasing the time required for a given total consolidation to occur.
Pulp and paper-mill sludge is similar to an organic soil called peat.
For some peats, the time for consolidation has been shown to be accel-
erated by surcharge, by a factor of thousands (25). For example, a
10-ft-thick layer of peat that would take 30 years to consolidate
could theoretically be consolidated in 10 days by the proper use of a
surcharge load.
Because of the initial high water content and low strength of fresh sludge,
the initial surcharge thickness probably should not exceed about 3 ft. (This
recommendation is based on field experiences with peat discussed in Refer-
ence 25.) Greater initial thickness may cause failure of the sludge from a
shear strength and bearing capacity (ability to support load) consideration.
If, when placing the 3 ft of surcharge, lack of the sludge material to support
it is evident, the surcharge thickness should be reduced to a supportable
13
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amount. However, some type of membrane or mat may be used to supply support
without reducing thickness of the surcharge. (Membranes are discussed under
Suggested Construction, page 22.) If greater surcharge thickness is desired
in order to induce a larger amount of consolidation and/or further decrease
the time element, the following recommendations are made:
a. Bearing capacity of the sludge material should be checked (25, 26,
or 27, or 28).
b. Application of the surcharge could be made in stages (layers) if the
sludge-bearing capacity is not sufficient. Between each stage, time
(weeks) should be allowed to elapse such that an amount of consolida-
tion would occur- Consolidation causes the material to increase in
strength, thereby allowing it to support greater loads. Therefore,
each increment of consolidation between surcharge stages increases
the strength for the next load. (Calculation of consolidatio and
time rates will be covered under Consolidation, Settlement, and Slope
Stability, page 2U.)
c. A membrane or mat could be used to increase the sludge supporting
ability, thereby allowing greater surcharge loads. Obviously, a
membrane or mat could be used in conjunction with stage construction.
The economics involved with the use of greater surcharge loads should be
balanced against the benefits gained from increased usable landfill volume
and accelerated consolidation time. The most economical material to use
for the dikes and surcharge loads would be earth material existing at or
near the landfill site.
DRAINAGE
Drainage is a highly important factor that must be considered for the fol-
lowing reasons:
a. A large volume of water will be forced out of the sludge material.
The sludge and water will be contained within the dike-enclosed area;
therefore, adequate drainage of the water from the enclosed area must
be accomplished.
b. The time rate of consolidation is theoretically related to the square
of the shortest drainage path through a material. Therefore, by ade-
quately controlling the distance or thickness through which a mate-
rial must drain, the consolidation time can be accelerated by a fac-
tor of hundreds. For example, a material of constant properties that
is drained through a 10-ft thickness could theoretically have its con-
solidation time accelerated by a factor of UOO if it was drained
through two 5-ft thicknesses. In other words, if the 10-ft drainage
path resulted in 30 years for an amount of consolidation to occur, the
5-ft drainage paths would allow the same consolidation to occur in
27 days.
Ill
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In order to accomplish drainage from the enclosed area and to accelerate
consolidation, drainage "blankets should be utilized. If contamination of the
groundwater could "be a problem, appropriate action should be taken (discussed
previously on page 9). The drainage blankets should consist of clean sands
and/or gravels and should be about 1 ft of uniform thickness extending over
the entire enclosed dike area. Outlets through the dike for the drainage
blankets must be provided. A water collection pocket about 3 to h ft long
consisting of gravel, intersecting each drainage blanket, and tapped with a
pipe no smaller than 6 to 8 in. should provide adequate drainage. Drainpipes
should extend out from the dike a sufficient amount so that discharge will not
erode the dike. The drainage blankets should be placed in the bottom of the
enclosed fill area (if the elevations are such that it will drain the enclosed
area), not less than every 8 to 10 ft of fresh sludge material, and at the top
of the fill prior to placement of the surcharge load. If no drainage blanket
can be used at the bottom of the fill, the first blanket should be about 5 ft
above the bottom of fill. The above-mentioned drainage blanket spacings allow
vertical drainage paths of about U to 5 ft in each sludge layer.
Shown in Figure 5 is a cross section of a dike and a portion of sludge
fill illustrating the use of a dike, drainage blankets, water collection
pockets, drainpipes, and surcharge load. If the landfill site has a solid
foundation (such as an old rock quarry) so that deformation or consolidation
beneath the sludge fill will be negligible, the middle drainpipe of Fig-
ure 5 could be eliminated. However, the middle drainage blanket would have
to be connected to the lower blanket. This connection could be made by a
5- to 10-ft-wide by 1-ft-thick layer of sand or gravel on the dike slope.
The full surcharge load should not extend to the dike, because the less
thick sludge on the dike slope will consolidate more than that away from the
slope. Water from the fill area can be channeled or collected from the
drainpipes and disposed of as necessary.
POSSIBLE PLAN FOR LANDFILL AREAS
Assume that a large landfill site is available and that several confine-
ment areas are required to cover it. One possible system of progressively
constructing and filling enclosed areas is presented in Figure 6 with the
following recommendations:
a. In order to adequately maintain drainage of each new enclosed area,
the areas should start in the center of the landfill site and
progress outward.
b. New enclosed areas adjacent to old ones should have their drainage
blankets connected to the older area ones. This connection can be
either a direct intersection in the case of the older dikes being
removed or through the existing drainage pipes in the case of the
older dikes not being removed. Drainage of the older fill areas
should be allowed to continue, because of slow continuing consoli-
dation or new consolidation induced by sludge being placed on top
of the old.
15
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c. After the sludge consolidation of an enclosed area, the earth dikes
may or may not "be removed. The choice of removal should be based
on an economic consideration involving the following factors:
(l) Availability and cost of earth materials for new dikes.
(2) Cost of removing old dikes and constructing new ones from the old
materials versus using new materials.
(3) The sludge fill volume gained by removing the dikes.
d. The choice of removing and reusing surcharge material after sludge
consolidation should be based on economic factors similar to the
preceding ones. However, if fresh sludge is to be placed on top of
consolidated sludge, part or all of the existing surcharge materials
may be desired as a supporting surface for construction equipment
and trucks. The need for a supporting material would depend on the
strength (ability) of the consolidated sludge to support the
equipment. If the surcharge material is removed and supporting
material is needed for equipment, an earth material road could be
placed on the consolidated sludge.
e. If surcharge materials are removed, the top drainage blanket mate-
rials may also be reused for another area. The cost of sand or gravel
drainage materials may justify removal of the surcharge loads.
f. If sludge disposal is to continue upward, the surcharge material may
be used for constructing the new enclosing dikes after consolidation
of the lower sludge. The top drainage blanket then becomes the bot-
tom drainage blanket for the fresh sludge. An upper disposal area
should not begin until at least adjacent lower areas have been filled
and partially consolidated.
As can be seen in Figure 6, planning the arrangement and construction sequence
of enclosing areas results in only one dike side needed for some areas. Plan-
ning also results in efficient use and reuse of materials.
CONSTRUCTION CONSIDERATIONS
Enclosed area dimensions, dike construction, and sludge placement methods
will be directly controlled by the consistency of the sludge material. For
convenience, sludges will be divided into two very general behavior catego-
ries: fluid behavior and plastic behavior. A fluid-type sludge will tend to
flow in a viscous slurry when unconfined. A plastic-type sludge will not flow
but will form a self-supporting mound when unconfined and will have a dry
appearance.
Fluid and semiplastic type sludges will limit one of the enclosed area di-
mensions because they will have to be spread and leveled with a crane dragline
or similar equipment working from the dike. Drainage blankets and probably
the surcharge material will also have to be spread with the dragline due to
16
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the sludge not being able to support equipment. One dimension of the enclosed
area must be limited to twice the working length of a dragline. (The average
dragline working length is about U5 to 50 ft.) This limit will allow a drag-
line to reach the center of the area from either of two dike sides. The limit
dimension of 90 to 100 ft is measured from the inside edges at the top of the
proposed dikes. An inside dike slope of ^5 deg (l:l) is a good inclination
angle for design and construction.
An enclosed area does not have to be a square; it could be rectangular
or any other shape. However, the above-mentioned limitation specifies that
the shortest dimension be about 50 ft from the center to a dike side. A
rectangular area would be limited to about 100 ft in width but could be any
length. Due to the deficiency of knowledge and experience concerning the
plastic-type sludges and knowing they are initially low in strength, the
above-mentioned limitation seems reasonable for all sludges. If equipment for
placing plastic sludge cannot operate directly on the fresh material, a drag-
line from a dike side would have to be used.
Assume here that sufficient earth materials for the dikes and surcharge
loads are available at the landfill site. If the area to be enclosed does
not have an approximately level surface, some material for the dikes can be
obtained by leveling the area with a bulldozer. The area can also be exca-
vated to obtain dike and surcharge materials. However, excavation should not
be so deep that water would not drain from the bottom or first drainage
blanket. Further assume that the site has now been prepared consistent with
the discussion on page 16 and the bottom drainage blanket (if there is to be
one) and drainpipes have been placed.
With the assumptions above and for a fluid-type sludge, the following sug-
gestions for possible construction are made:
a. Begin the earth dike construction by bulldozing a U- to 5-ft height
around the sides of the fill area, maintaining the design enclosed di-
mensions and slope. Some compaction of the dike material is achieved
from the tractor. The outside dike slope could be as-constructed but
with a section of low inclination angle in order to allow a ramp for
equipment and trucks to get to the top of the dike. If sludge is to
be brought in by trucks, an opening in the dike could be left on one
side for the trucks. The trucks could also dump from the dike, or the
sludge could be piped into the fill area. Care should be taken not to
disrupt the bottom drainage blanket. A dragline, working from the
dike sides, would be needed to spread the sludge.
b. With the first ^ to 5 ft of sludge in place, a drainage blanket and
drainpipes would be needed if they were not placed at the bottom.
(However, assume they are at the bottom.) The dike construction could
now continue for another h to 5 ft in height, and it could be widened
as necessary to provide a convenient width for equipment. Sludge
would now be placed again by truck or pipes and spread by the dragline,
The operations would continue until a sludge design thickness was
reached, at which point another drainage blanket would be required.
17
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c. The sludge surface should be approximately level, and this could be
done by the dragline pulling a raft across the surface. A raft could
be made by lacing together several logs, poles, pipes, etc. The
gravel drain pockets, drainpipes, and drainage blanket should now be
placed. Depending on the strength of the sludge, the following pro-
cedures could be used for placing the drainage blanket:
(l) If the sludge would support the drainage blanket material plus a
small lightweight tractor with extra track width, the blanket
could be placed by the tractor spreading material ahead of itself.
(2) If the sludge would support the drainage blanket only, then the
material could be placed, spread, and leveled by the dragline.
(3) If the sludge would not support the drainage blanket, some kind
of porous membrane or mat for support would have to be used on
top of the sludge. Drainage blanket material could then be placed
by the above-mentioned methods. Porous membranes are materials
such as burlap, wire mesh sheets, special plastic sheets (such as
in Reference 29), possible porous paper sheets, etc.
d. Construction of the fill area should continue for the upper sludge
layers as in the previous steps. At the top of the fill, a drainage
blanket and surcharge must be placed. Methods for placing these
would be the same as in c, above. Figure 7 illustrates, in general,
the above-suggested fill area construction steps.
For a plastic-type sludge, construction of an enclosed fill area may be
simpler. The above-mentioned steps should be followed in general. However,
if a lightweight tractor can operate on top of the sludge, placement could be
made with the tractor and in thicker layers. Also, if a tractor could be
used, no problems would occur in placing drainage blankets and surcharge
loads. If the sludge will not support a tractor, then the construction steps
for a fluid-type sludge would have to be followed.
18
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SECTION III
CONSOLIDATION, SETTLEMENT, AND SLOPE STABILITY
CONSOLIDATION THEORY
Pulp and paper-mill sludge consists of solid constituents between which
are spaces (voids) filled with air or water. The void space of the sludge in
the fill (or, in another sense, the sludge density), the amount of water con-
tained in the void spaces (water content), and the sludge permeability are of
concern, because these affect the strength and settlement (vertical displace-
ment) of the sludge. Figure 8 is a summary of weight and volume relations
for a sludge sample. Appendix B presents the laboratory test procedures for
determining- the physical properties necessary in understanding and predicting
the behavior of sludge.
Most sludges will be 100 percent saturated (all void space filled with
water). If a saturated sample is subjected to a one-dimensional load (Fig-
ure 9), the decrease in volume is accomplished by water being squeezed from
the voids at a rate controlled by the sludge permeability. This process is
termed consolidation. The change in height, AH , per unit of original height,
H , equals the change in volume, AV , per unit of original volume, V .
AH
Hl
AV
V,
AV can be expressed in terms of void ratio, e , and AH becomes
AH = H.
Ae
1 \1 + e.
= H,
P — P
• 1 2'
This relation is for primary compression, which is due entirely to the de-
crease of water volume. Secondary compression occurs after primary compres-
sion and may be related to a plastic creep deformation and compression of the
constituent particles. The rate of consolidation can also be calculated. The
prediction of the rate of consolidation usually has the largest error because
of changing consolidation parameters, secondary compression, and construction
rate (increasing load rate). Detailed discussion of consolidation theories
can be found in References 7-9- Stress-strain characteristics of sludge can
be determined in the laboratory (Appendix B) and applied together with the
consolidation theory to predict sludge settlement and rate for landfills.
19
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SETTLEMENT PREDICTION
Vertical Stresses
The vertical stress acting on a horizontal plane at depth, s , is equal
to the weight of all matter that rests above the plane,. If the unit weight of
the matter is constant with depth, the stress at depth, z, , is equal to the
depth multiplied by the wet unit weight, Ym (Appendix B, Unit Weights). A
load-depth diagram is usually constructed by plotting stress versus depth as
in Figure 10. The total initial stress, Po , at any depth may be obtained
from the diagram. Sludge materials have extremely high water contents and
large volumes of water. When placed in a contained landfill, a pond of wa.ter
is essentially created and the sludge constituents are held in suspension.
The water exerts a hydrostatic pressure, u (Figure 10), as a. function of
depth, on the sludge constituents. As a result of the hydrostatic pressure,
the effective contact stress, P'Q , between sludge particles is reduced by the
magnitude of u (Figure 10). In other words, the sludge particles support a
load of P0 - u only. The average vertical stress within a layer acts very
close to the middepth of the layer; therefore,, it may "be taken at the middepth
point with negligible error (about 10 percent). In Figure 10, the average ef-
fective stress in the sludge layer is PQ = 138 Ib/ft^. In Figure 11, if a
load AP is added to the sludge layer of Figure 10, the resulting effective
stress is P^ + AP , and the average stress is P' = (138 + A.P) lb/ft2.
Settlement
Once data from laboratory tests (Appendix B) and from stress analysis
are available, the settlements for a landfill design can be easily obtained.
In order to make settlement computations, a landfill design height and the
number of layers should be selected,, From the laboratory tests, sludge wet
unit weight, Ym , has been determined and the a.verage initia.1 effective
stress, PQ , for each design sludge layer can be calculated. The total
load, AP , above each sludge layer can now be calculated (for sand,
Ym ^ 100 lb/ft-3; for surcharge, ym ^ 120 lb/ft3). Total load, AP , equals
the wet weight of all sludge, sand, and surcharge layers above the one being
considered. The primary settlement, AH • , for a sludge layer is computed
by the equation
where AH . = primary settlement
pri
C = compression index determined from laboratory tests (Appendix B,
Consolidation Test), Plate B-13. (if the laboratory pressure-
void ratio plot is curved and P' corresponds to a laboratory
pressure in the curved region, Cc should be taken as the
tangent at the point P ^ P' .)
H = total initial thickness of the sludge layer. In Figure 11,
Ht = 2H
20
-------
eQ = initial void ratio existing at P^ , obtained from laboratory
tests (Appendix B, Consolidation Test), Plate B-13.
P^ = average initial effective stress within the sludge layer, as
previously described
AP = total load above the sludge layer, as previously described
To compute settlement from secondary compression following primary consolida-
tion, use the following equation:
t
= C H. loe_.
sec
AH = C H. logn . T
a t to!0 t
pri
where AH = settlement from secondary compression
C = coefficient of secondary compression obtained from the labora-
tory tests (Appendix B, Consolidation Test) (Plate B-12) for
the total laboratory load increment corresponding to P' in
the field
t = time for which settlement is significant
sec °
t . = time to completion of 100 percent primary consolidation
For one cycle of log time
AH = C H. log,..
sec a t 10
AH = C H,
sec a t
Total settlement is equal to
AH _,_ , = AH . + AH
total pri sec
If sludge materials having largely different compression indexes are
placed within a layer, the settlement of the total sludge layer can be cal-
culated by the following equation:
n
AH^ , . = AH, + AH0 . . . + AH = Y AH
total 1, , . 2 n, , , i n
total total total 1
where n = individual layers of different sludge within a single layer of
sludge
Time rate of settlement is computed by the following equation for
primary consolidation:
21
-------
TH2
pri ~ C
v
where t = time for primary consolidation in the field
pri
T = dimensionless time factor related to the percentage, U , of
primary consolidation. Figure 12 is a curve for T versus U
from which values of T can be obtained
H = length of longest vertical path for drainage of water. For
drainage to pervious layers at top and bottom of the sludge
layer, H = Ht/2 . For drainage to only one pervious layer,
H = Ht
C = coefficient of consolidation determined from the laboratory
V tests (Appendix B, Consolidation Test) (Plate B-12) for the
total laboratory load increment corresponding to P' in the
field.
Primary settlement time rate, tpri , can also be determined from the
nomograph in Figure 13. Figures 12 and 13 correspond to instantaneous load
applications .
If load AP application is gradual and construction time is appreciable
compared with time required for primary consolidation, the time factor curves
of Figure lU should be used to obtain the T values for the field time,
5 equation. (Figure l.k is strongly recommended to be used at all times.)
In Figure 1^ , T is determined from
o
C t
T =
H2
where to = end of construction time . to can be estimated from the volume,
Vf , of the landfill and the pulp and paper-mill sludge production rate,
Vs/day y
to = ~ in days
s
T and U during construction (prior to to ) are given by the upper envelop-
ing dashed curve to the point of calculated To . After the end of construc-
tion time to , T and U are given by the dashed curve corresponding to
TO •
The time for secondary consolidation is tsec , as defined previously.
If one cycle of log time is used for computing AHsec , tsec = 10 x
The time for total settlement to occur is
t = t + t
total 100 percent pri sec
22
-------
where t , , = time for total settlement to occur
total
t . = time for 100 percent primary settlement to occur
100 percent pri
= chosen time over which to compute the amount of
secondary settlement
For a layer of sludge with materials having largely different coefficients of
consolidations, use an average Cv for the time computations. Settlement
time plots (Plate 1 is a suggested form) should be made for the sludge layers
of a landfill. The curves will show the importance of time and will indicate
when retaining dikes could possibly be removed. Dikes can be removed after
about 90 percent total settlement has occurred.
Possible Errors
Sources of error for both consolidation and time rate predictions are
listed below.
a. Nonrepresentative laboratory specimens.
b. Inaccurate laboratory data.
c. Nonhomogeneous sludge material within the layers.
d. Decreasing coefficient of permeability with consolidation.
e. Construction rate cannot be accurately considered.
f. Inaccurate load estimate, AP . The actual thickness of the layers
will vary from design, because the lower layers will consolidate as
the upper layers are constructed. Therefore, greater thickness of
upper layers will result.
g. Change in sludge material properties as a result of construction and
consolidation.
SLOPE FAILURE CONDITIONS
After consolidaton of the sludge layers in a dike-enclosed area, the dikes
may be left in place or removed. If the dike material and the dike-occupied
space are not needed for continuation of sludge disposal, they may remain per-
manently and eventually be covered with sludge. However, if the space occu-
pied by the dike and the dike material are required for landfill continuation,
the stability of the consolidation sludge upon removal of the dike will have
to be considered. Three approaches may be taken: (a) the sludge may be al-
lowed to form a natural slope, (b) a slope having an angle of U5 to 50 deg may
be cut, or (c) a slope may be designed to prevent movement and breaking off of
material.
When landfill interior dikes are removed, sludge will be placed against
23
-------
the natural or cut slope; therefore, the sludge material that may have fallen
will not be a problem. If dikes along a landfill periphery are removed, safe
slopes should be designed. When sludge disposal is to continue upward, the
upper dikes should not be so close to a lower layer sludge slope as to cause
failure. Slope stability should be checked in order to design a safe distance
between an upper dike and a slope.
Failure of a slope or embankment is the rapid or gradual displacement of
a portion of the embankment relative to the remainder of the mass. The por-
tion that moves may do so as a slide, a rotation, or a displacement of a wedge
shape. Failures follow changes in shear stress or shear strength that lead to
unbalanced driving forces. Imbalance of forces is caused by changes in slope
profile, increase in water pressure, added weight to the top of the slope, or
time-conditioned decrease in shear strength due to weathering, leaching, miner-
alogical changes, opening and softening of fissures (cracks), or continuing
gradual shear strain. The possibility of movement occurring is evaluated by
comparing forces resisting failure with those causing failure. This ratio is
the safety factor.
Slope Design Considerations and Stability Analysis
Because of the sand drainage blankets between sludge layers, failure is
most likely to be in the form of a wedge of sludge material displacing with
translational motion along or through a sand layer. The slip or failure sur-
face will be a composite slip surface through the sludge and along the sand
layer. Analysis of a failure of the above-mentioned type can be made using a
procedure of slices and a composite slip surface (8). The analysis method
presented below is based on total stress and not on effective stress, because
pore pressures within sludge will not be known.
In order to design a safe slope, a slope angle is assumed and the minimum
factor of safety is calculated. The procedure is repeated for other assumed
slope angles until a satisfactory or design factor of safety is acquired.
Once the design factor of safety is obtained, the corresponding slope angle is
the angle at which the sludge slope should be cut. Because the analysis pro-
cedure is based on total streases, a minimum design factor of safety of about
1.5 for landfill interior sludge slopes against which sludge will eventually
be placed seems reasonable. A minimum design factor of safety is the value
at and below which a failure might possibly occur. For landfill periphery
sludge slopes which should have a long duration and because of total stress
analysis, the design factor of safety of about 2.0 seems reasonable.
Design and analysis procedures for consolidated sludge slopes are as
follows:
a. Choose a trial slope angle, 3, as shown in Figure 15. A $ between
45 and 50 deg would be a good starting point.
b. Choose a trial slip (failure) surface such as trial 1 in Figure 15.
Because total stress analysis is being used and the sludge material is
initially undrained when a slope is cut, the sludge angle of internal
fraction, cj>, is equal to 0. Therefore, the slip surface through the
2k
-------
sludge layers can always be taken at an angle a = ^5 deg. The slip
surface angle through the sand layers and through the surcharge mate-
rial is ct]_ = ^5 deg + /2 . A good approximate friction angle, $ ,
for the sand and surcharge is <|> = 30 deg; therefore, a = 60 deg.
For the trial 1 slip surface, there is no angle 013 . However, for
the other trial slip surfaces shown, a-? and ct^ are determined (as
shown in Figure 15) "by the location of the trial slip surfaces through
the sludges.
c. Divide the sliding mass into slices. For convenience, the slices can
"be taken at points separating zones of different material properties
or at points where a break occurs in the upper or lower boundary of
the sliding mass as shown in Figure 15.
d. Set up a table as shown below and fill it in (8).
Tabular Computation
Values from the Cross Section Computed Values
Slice Ax P Sy * B A' N A
No. tan a ft psf psf deg o o a o
1
2
3
k
Note that a = angle at base of slice
Ax = slice width, ft
P = average vertical total stress on base of
slice (ym x depth to center point of
slice base). Ym (Appendix B, Unit
Weights) average for each sludge layer
can be obtained from the average water
content, wavg (Appendix B, Solids and
Water Contents) for each layer as
, - \ j_ . w / i ,
m avg I 1
avg \w + —
& » avg G
Sy
G = specific gravity of solids (Appendix B,
Specific Gravity). The average water con-
tents can be determined from the material
adhering to the vane shear test device
(Appendix B, Vane Shear Test). The
25
-------
equation above assumes 100 percent satu-
ration of the sludge.
S = S (Appendix B, Vane Shear Test)
vane
x y = average undrained sludge shear
strength at base of slice. M = correc-
tion factor from Figure l6.
= angle of internal friction for the sand
and surcharge
B = P x tan a x AX
o
A1 = Sy x AX for sludge base. A^ = P x tan <|>
0 x AX for sand and surcharge base
N =1.0 for sludge base
a
2 /n tan a tan d> \
N = cos a 11 + -I for sand and sur-
a \ F /
charge base
A'
Ao = ~
a
Calculate the summations of the Bo and Ao
columns, VB and VA
f-> O L* O
e. Calculate the factor of safety, F , by successive approximations
or by solving for F in the equation
A
Successive approximations or solution for F are required, because
F appears on both sides of the equation above.
f. Repeat steps b through e taking different trial slip surfaces until
the minimum factor of safety is found for trial slope angle 3 .
g. Choose other trial slope angles, 3 , and find their minimum factors
of safety by steps a through f.
h. For interior landfill sludge slopes, the g with a corresponding F
greater than 1.5 vould be a good design slope. For periphery landfill
sludge slopes, the 3 with a corresponding F about 2.0 would be a
good design slope.
The field experimental example presented in the next section should help
clarify some of the procedures described above.
26
-------
SECTION IV
FIELD EXPERIMENTAL EXAMPLE
RETAINING STRUCTURES AND SLUDGE PLACEMENT
An experimental paper-mill sludge landfill was constructed and monitored
during the period 1971-1972 (6-9, 30, 31) to obtain engineering information
essential to developing procedures for the design and operation of pulp and
paper-mill vaste landfills. The work was sponsored by the EPA and NCASI.
Kimberly-Clark Corporation-Morraine Mill, West Carrolltori, Ohio, provided the
landfill site and dewatered sludge. The landfill site was an old gravel pit
near West Carrollton, The experimental fill consisted of two sludge layers,
initially 10 ft thick, with 1-ft-thick sand drainage blankets at the top,
middle, and bottom. An earth dike provided lateral confinement of the sludge,
and a surcharge load consisting of 3 ft of natural soil was used. A lysimeter
study provided information on changes in quality of the leachate when passed
through selected natural soils. Figures 17 and 18 show the landfill in a
plan view and typical cross section, respectively.
For the dike construction, a 35-ton Link Belt power shovel was used for
the excavation work and a D-6 Caterpillar tractor was used to move the exca-
vated earth material and shape the dikes. The dike sides were constructed
with one corner left low for placing sand in the fill bottom. After spreading
sand for the lower drainage blanket, the dike was closed and sludge was dumped
from trucks over the west and south dike walls. Even though the sludge exhib-
ited a plastic behavior, it would not support the D-6 tractor- Therefore, the
power shovel was converted into a dragline unit and proved ideal for spreading
the sludge. A lightweight tractor with extra-wide tracks was obtained, but it
arrived too late for use in spreading the lower sludge layer and because the
dike had been fully constructed, it was not used for the upper sludge layer -
When the lower layer of sludge was sufficiently thick, it was leveled with
the dragline by dragging two telephone poles cabled together across the sur-
face. Sand for the middle drainage blanket was then dumped along one dike
wall, distributed by the dragline, and leveled with the dragline/telephone
pole arrangement. The lightweight tractor was not used with the middle sand
blanket because the dikes had been completed, and manuevering the tractor in
and out of the field would have been difficult.
When the upper sludge layer reached the desired thickness, it too was
leveled by dragging the telephone poles. Sand was dumped along one dike wall
and was spread by the lightweight tractor pushing the sand ahead of its path.
Because the sand acted as a supporting mat, the small tractor had no diffi-
culty in working on the landfill surface. Sand placement with the small
27
-------
tractor was faster than with the dragline. Both the D-6 and small tractor
vere used for spreading the earth surcharge material. The surcharge material
was dumped onto the landfill surface by the dragline.
SLUDGE MATERIAL
The dewatered sludge used in the landfill had the physical properties
shown in Table 8. These properties were determined from samples taken at
various elevations as the sludge was placed; determinations were made in ac-
cordance with the tests described in Appendix B. Therefore, the properties
represent the initial, as-placed sludge conditions.
CONSOLIDATION AND SETTLEMENT
Figures 10 and 11 give the initial average effective stress, P'
= 138 lb/ft2 (discussed in Section III) for each 10-ft-thick layer. The total
load acting on the lower sludge layer, AP]_Ower 5 is calculated as follows:
a. Weight of sludge (design thickness) above lower layer
= 10 ft x 70 lb/ft3 = 700 lb/ft2
b. Top sand layer weight = 1 ft x 100 Ib/ft3 = 100 lb/ft2
c. Surcharge weight = 3 ft x 130 lb/ft3 = 390 lb/ft2
d. APlower = (700 + 100 + 390) lb/ft2 = 1190 lb/ft2
e. Average effective stress P' = P' + AP_, = (138 + 3190) lb/ft2
lower o lower
= 1328 lb/ft2 = 0.66^ ton/ft2 ~ 0.66k kg/cm2
The total load acting on the upper layer, APIlpper , is the weight of the sand
blanket and surcharge. The sand blanket weight is included in P^ „ There-
fore, APupper = 3 ft x 130 lb/ft3 = 390 lb/ft2 = surcharge weight . The av-
erage effective stress is P' - P1 + AP - (138 + 390) lb/ft2
upper o " upper y ' '
= 528 lb/ft2 = 0.261* ton/ft2 « 0.26U kg/cm2.
Figure 19 shows the consolidation characteristics (discussed in Sec-
tion III) for the sludge used in the experimental landfill. Using the settle-
ment equation
C H. / P1 + AP\
C t I O \
pri 1 + e V-^lO P1 /
o \ o /
defined previously in Section III, the primary settlement for each layer can
be calculated as follows:
a. Lower layer properties.
28
-------
Cc = 1.65
H = 10 ft
TJ
e = U.85 at P'
oo
P' =138 rb/ft2
o
APn = 1190 lb/ft2
lower
- (1.65)(10 ft) /. 1328 lb/ft 2
. 138
= 2.82 ft x 0.9833
= 2.77 ft = 33.28 In.
c. Upper layer properties.
C = 1.65
c
H = 10 ft
"C
e = U.85 at P'
o o
P' =138 lb/ft2
o
AP = 390 lb/ft2
upper
, AW _ (1.65)(10 ft) / 528 Ib/ft2\
a. AH - — - - i — Q-: - lloe_ _ - — I
pri 1 + U.85 \ 10 n_p -.,,,,.21
* upper \ 138 lb/ft /
= 2.82 ft x 0.582
= 1.6U ft = 19-T2 in.
Secondary settlement, defined previously in Section III as
/ q pf*
AH = C H,
sec at r^b!0 t . /
\ pri/
can be calculated as follows:
a. Lower layer Ca = 0.018 from Figure 19 laboratory tests corresponding
to P' = 0.66U ton/ft2.
lower
b. Ht = 10 ft.
c. For one cycle of log time
29
-------
AH = C H.
sec., a t
lower
= 0.018 x 10 ft = 0.18 ft
= 2.16 in.
d. Upper layer Ca = 0.0l6 from Figure 19 laboratory tests corresponding
to Pepper = 0.26*4 ton/ft2.
e. Ht = 10 ft.
f. For one cycle of log time
AH = C H,
sec a t
upper
= 0.016 x 10 ft = 0.16 ft
= 1.92 in.
Total settlement (Section III) for the landfill is calculated as follows:
a. Lower layer AH, _, n = AH . + AH = 33.28 in. + 2.l6 in.
total-. pri sec
lower
= 35.^ in.
b. Upper layer AH = 19.72 in. + 1.92 in. = 21.6U in.
"C O~C £L_L
upper
c. Total for the landfill
AH = AH.. _ + AH,
total total, total
lower upper
= 35. W in. + 21.6*1 in. = 57.08 in. = ^.76 ft
The rate of settlement is calculated as previously defined in Section III.
For the field experimental landfill, settlement rates are calculated as
follows:
a. Lower layer GV = 0.013 in.2/min =0.13 ft2/day from Figure 19 labo-
ratory tests corresponding to average load between 0 and piower »
which was 0.332 ton/ft .
b. For use of Figure Ik (Section III). Construction period from begin-
ning to end was 62 days; therefore, take to = 62 days. This time
includes the construction of the lower layer in addition to construc-
tion of the load APn . Use of t =62 days and starting the
lower o
30
-------
settlement-time plot (presented later on page 60) at time 0 fit the
final portion of the field measured behavior data curve fairly good.
The procedure above assumes that consolidation of the lower sludge
layer actually begins during its construction, and fit of the pre-
dicted and field data tends to make the assumption good for times
after about Uo percent of total consolidation.
c. H = 5 ft.
d
'
T =
°
vt° = (0.13 ft2/day)(62 days) = Q
H2 25 ft2
e. From Figure
U ,
percent
0
10
20
60
80
90
100
T
0
O.OlU
0.060
0.260
O.i+00
0.660
0.950
2.000
f. Time for primary consolidation in the field is calculated as follows:
(l) H - 5 ft
Cv - 0.13 ft2/day
TH
2
pri
n
lower
v
2
rp
— 1
0.
T
0
O.Olll
0.060
0.260
oAoo
0.660
0.950
2.000
'5 ft2
lower .__ ., 0
13 ft /day
t (days)
pri.
lower
0
2.69
11.5^
50.00
76.92
126.92
182.69
38U.62
. 3 days
g. Percent consolidation in the field is calculated as follows:
Percent AH
.
pri
^
= U x AH
lower
lower
31
-------
U , AH percent AH . , in.
, \ pri /
percent \ lower/
0 0
10 3.328
20 6.656
UO 13-312
60 19.'
80 26.628
90 29.952
100 33.280
h. Plot time, t^^. , versus settlement, [AH percent AH^^. J as
-p-L^-l T".-n -1
in Figure 20.
pri V Prin
lower \ lower/
i. Upper layer Cv = 0.016 in.2/min = O.l6 ft2/day from Figure 19 labo-
ratory tests corresponding to average load between 0 and P' ,
which was 0.132 ton/ft2. upper
j. t0 = 30 days for upper layer construction and surcharge. H = 5 ft .
k. For Figure lU.
T _ Cvto = (0.16 ft2/day)(30 days)
° " ft2 " 25 ft2
= 0.192 ** 0.2
1. From Figure ]_h .
u ,
percent
0
10
20
ho
60
80
90
100
T
0
O.OlU
0.060
0.220
0.3^0
0.620
0.900
2.000
m. Time for primary consolidation in the field is calculated as follows:
(1) H - 5 ft
Cv = 0.16 ft2/day
2 2
(2) t = ^- = T ^-^| = T x 156.25 days
upper v O.l6 ft /day
32
-------
T
0
o.oiU
0.060
0.220
0.3^0
0.620
0.900
2.000
pri
> days,
upper
0
2.19
9.38
3^.38
53.13
96.88
1^0.63
312.50
n. Percent consolidation in the field is calculated as follows
Percent AH
pri
= U
upper
AH
pri
upper
U ,
percent
0
10
20
UO
60
80
90
100
AH percent AH , in.
\ pri /
\ __ upper/
0
1.972
7.
11.832
15.776
17-7^8
19.720
o. Plot time, t . , versus settlement, AH percent AH I as
pri ' \* pri /
upper \ upper/
in Figure 21. Time t . starts at the upper layer construction
upper
start time, 32-day point in Figure 21.
p. The secondary consolidation amounts and times (10 x tprj_) for the
lower and upper layers can be added to Figures 20 and 21.
The theory of consolidation assumes settlement starts as the load AP is
added to each sludge layer. Therefore, the settlement prediction curves
should have started at 32 days in Figure 20 and at 62 days in Figure 21. How-
ever, assuming, as in the previous steps, that settlement started with each
layer's construction gave a better fit of the predicted and measured time
rates. Had the AH+ + -. for each layer been used instead of AHprj_ , the
settlement-time curves would have been closer to the measured data.
SLOPE STABILITY
A slope was cut in the consolidated sludge material in order to investi-
gate the applicability of stability analysis. Failure occurred in the slope,
33
-------
and the composite slip surface analysis was found to be the most applicable.
Prior to cutting the slope, vane shear tests (Appendix B, Vane Shear Test)
were conducted, and results are shown in Figure 22 for both undisturbed and
remolded conditions.
Figure 23 shows a cross section for the cut slope and the approximate zone
of failure. Material moved out of the slope about 5 to 6 ft back from the top
of the original cut. However, surface tension cracks occurred as far back as
16 ft from the top of the original cut. The tension cracks indicate material
movement and slumping. The sludge wet unit weights (Appendix B, Unit Weights)
shown in Figure 23 are averages determined from undisturbed material samples.
The process of consolidation increased the unit weights.
Figure 2h is a cross section of the top sludge layer. Shown in the figure
is a trial failure surface, 1, and five slices for computing the stability as
previously described in Section III. Stability is analyzed as follows:
a. Fill in a table of necessary values (discussed in Section III).
Values from the Cross Section
Slice
Wo. tan a
1 1
2 1
3 1
U 1
5 1
.73
.00
.00
.00
.00
AX
ft
2
3
2
1
1
.1+
.8
.5
.0
.0
P
psf
260
635.2
658.0
5^0.1
279-5
su
psf
768.1
983.2
1339-6
1339-6
deg
30
0
0
0
0
Computed Values
B
o
1079-5
21+13.8
161+5.0
51+0.1
279-5
A'
o
360.3 o
2918.8
21+58.0
1339-6
1339.6
N A
a o
^r- . 0.25 360.
' ''^ V
0.25 +
i.o 2918.
i.o 21+58.
1.0 1339.
1.0 1339.
3
0 25
~F
8
0
6
6
(l) The average vertical total stress P acting on the base of each
slice is:
Pslice 1 = 13° pcf x 2 ft = 26° psf
Pslice 2 = (13° X 3) + (1°° X 1} + (T2'6 X 2) = 635'2 psf
Pslice 3 = (13° X 1>5) + (1°° X 1} + (T2'6 X 5) = 658'° psf
P -, . i = (100 x 0.5) + (72.6 x 6.75) = 5ll0.1 psf
slice 1+ ^
p =72 6x77x05= 27Q 5 nsf
slice 5 ^
(2) Average undrained sludge shear strength at the base of each slice
is:
S = S (Appendix B, Vane Shear Test) x y
vane
-------
From Figure l6, y = 0.6 . From Figure 22, obtain average S
vane
for each slice with a sludge base. Vane shear tests conducted
after the slope was cut gave undisturbed values closer to the re-
molded ones shown in Figure 22. Therefore, S
vane
values should
probably be the remolded ones. Unloading from cutting the slope
apparently reduced the shear strengths. (Sy remolded values were
used in the table above.)
(3) Calculate for each slice
B = P x tan ct x AX
o
Calculate for each slice
For sludge A' = S x AX
For sand and surcharge A' = P x tan
AX
,5) N =1.0 for the sludge bases. For the surcharge base
2
,T 2 cos a tan a tan
N = cos a +
a F
- 0.25
(6) Calculate A = A'/N
o o a
b. Calculate the factor of safety, F
approximations or direct solution.
, by either successive
= 8056.0
= 595T-9
8056.0 +
360.3
5957.9
By direct solution:
= 8056.0 360.3
5957-9
35
-------
F = 1.352 +
1U89.5
(F - l.352)(lU89.5F + 1^89.5) = 360.3F
1H89.5F2 + 1^89.5F - 2013.8 = 0
F2 - 0.5939F - 1.352 = 0
F2 - 0.5939F + 0.0882 = 1.1A02
(F - 0.29TO)(F - 0.2970) = 1..UU02
(F - 0.29TO)2 = 1.UU02
F - 0.2970 = 1.20
F = 1.^9
Another trial failure surface, 2, is shown in Figure 2U. Stability analy-
sis for surface 2 is as follows:
a. Fill in ta"ble as previously described.
Values from the Cross Section Computed Values
Slice AX P U <(> B A' 1^ A
Ho. tan ct ft psf psf deg ° ° _ ^ __ °
1 1.73 2.3 260.0 — 30 103U. 5 3^5.3 0.25 + ~~ --- 3^'
2 1.00 5.8 TOO. 5 676.0 0 ^062.9 3920.9 1-0 3920.9
3 1.00 2.5 795-9 921.9 0 1989.8 2301+.8 1.0 230^.8
0.33 1.0 665.3 - 30 219.6 38U.1 0.9 +
5 0.33 1.0 3U7.7 — 30 lilt. 7 200.7 0.
6 0.33 1.0 ItO.O — 30 13.2 23.1 0.9 +
b.
0.25 + ^~^ 0.9
V^B = 7U3U.68
£- o
36
-------
c. Factor of safety, F
F =
= 0 8374 + 3l*5-3 + 60T.9
1858.67 + i^Ml 6691.21 +
r r
= 1.006
Obviously, a less-abrupt slope angle is required for stability. Another slope
angle was cut at 53 deg in the field test sludge landfill, and no failure
occurred.
37
-------
SECTION V
REFERENCES
1. Subcommittee on Sludge Disposal, Committee on Sewerage and Treatment,
"Advances in Sludge Disposal in the Period October 1, 195^ to Febru-
ary 1, I960," Journal, Sanitary Engineering Division, American Society of
Civil Engineers, Vol 88, No. SA2, Mar 1962.
2. Dick, R. I., "Attitudes in Sludge Treatment and Disposal," Journal,
Environmental Engineering Division, American Society of Civil Engineers,
Vol 100, No. EE5, Oct 197^.
3. Miner, R. , Unpublished data, Oct 1971*, National Council of the Paper
Industry for Air and Stream Improvement, New York, N. Y.
IK McKeown, J. J. and Caron, A. L., "Sludge Dewatering and Handling Prac-
tices in the U. S. Paper Industry," Special report presented at Tech-
nology Transfer Seminar on Water Pollution Abatement Technology in the
Pulp and Paper Industry, May 1975, National Council of the Paper Industry
for Air and Stream Improvement, New York, N. Y.
5. Gillespie, W. J., "Current Practices in Land Disposal of Sludge," Special
Report (unpublished), Feb 1970, National Council of the Paper Industry
for Air and Stream Improvement, New York, N. Y.
6. "Shear Strength and Permeability of High Ash Pulp and Papermill Sludges,"
Technical Bulletin No. 252, Dec 1971, National Council of the Paper In-
dustry for Air and Stream Improvement, New York, N. Y.
7. "Consolidation Behavior of High Ash Pulp and Papermill Sludges," Tech-
nical Bulletin No. 257, Jun 1972, National Council of the Paper Industry
for Air and Stream Improvement, New York, N. Y.
8. Andersland, 0. B. et al., "An Experimental High Ash Papermill Sludge
Landfill: Second Annual Report," Report No. EPA-670/2-7U-076b, Dec 197^,
U. S. Environmental Protection Agency, Cincinnati, Ohio.
9. Andersland, 0. B., Vallee, R. P-, and Armstrong, T. A., "An Experimental
High Ash Papermill Sludge Landfill: First Annual Report," Report
No. EPA-670/2-7^-076a, Dec 197^, U. S. Environmental Protection Agency,
Cincinnati, Ohio.
10. Standard Methods for the Examination of Water and Wastewater, 13th ed.,
American Public Health Association, American Water Works Association,
Water Pollution Control Federation, Washington, D. C., 1971-
11. Gehm, H. W., "Current Developments in the Dewatering of Papermill
Sludges," Technical Bulletin No. 113, Mar 1959, National Council of the
Paper Industry for Air and Stream Improvement, New York, N. Y.
38
-------
12. Zettlemoyer, A. C., Micale, F. J., and Dole, L. R., "Surface Properties
of Hydrogels Resulting from Treatment of Pulp and Papermill Effluents,
Part II," Technical Bulletin No. 225, Dec 1968, National Council of the
Paper Industry for Air and Stream Improvement, New York, N. Y.
13. MacDonald, R. G., ed., Pulp and Paper Manufacture, Vol. Ill: Papermaking
and Paperboard Making, 2d ed., McGraw-Hill, New York, 1970.
lU. "The Relationship Between the Constitution and Dewatering Properties of
Hydrous Sludges," Technical Bulletin No. 260, Oct 1972, National Council
of the Paper Industry for Air and Stream Improvement, New York, N. Y.
15. Mazzola, C. A., Unpublished data, Oct 1969, National Council of the Paper
Industry for Air and Stream Improvement, New York, N. Y.
16. Gale, R. S., "Filtration Theory with Special Reference to Sewage
Sludges," Journal, Institute of Water Pollution Control, No. 6, 1967.
17. "Mechanical Pressing of Primary Dewatered Papermill Sludges," Technical
Bulletin No. Ijk, 197^, National Council of the Paper Industry for Air
and Stream Improvement, New York, N. Y.
18. Fungaroli, A. A., "Pollution of Subsurface Water by Sanitary Landfills,"
Vol 1 (Drexel Institute of Technology Solid Waste Management Research
Grant 000162), 1971, U. S. Environmental Protection Agency, Cincin-
nati, Ohio.
19- Emrich, G. H. , "Guidelines for Sanitary Landfills - Groundwater and
Percolation," Proceedings, Environmental Foundation Conference on the
Application of Environmental Research and Development on Landfill Dis-
posal of Solid Wastes, 2^-28 Aug 1970, Deerfield, Mass.
20. Salvato, J. A., Wilkie, W. G., and Mead, B. E., "Sanitary Landfill -
Leaching Prevention and Control," Journal, Water Pollution Control
Federation, Vol U3, No. 10, 208^, 1971.
21. "Report on the Investigation of Leaching of a Sanitary Landfill," Pub-
lication No. 10, 195^, California State Water Pollution Control Board,
Sacramento, Calif.
22. "In-Situ Investigation of Movements of Gases Produced from Decomposing
Refuse," Publication No. 3k, 1967, California State Water Quality Control
Board, Sacramento, Calif.
23. Springer, A. M. , Investigation of Environmental Factors Which Affect the
Anaerobic Decomposition of Fibrous Sludge Beds on Stream Bottoms, Ph. D.
Dissertation, Jun 1972, Institute of Paper Chemistry, Appleton, Wis.
2k. Imshenetsky, A. A., The Ecology of Soil Bacteria, University of Toronto
Press, Canada, 1968.
25. MacFarlane, I. C., ed., Muskeg Engineering Handbook, University of
Toronto Press, Canada, 1969-
26. Lambe, T. W., Soil Mechanics, Wiley, New York, 1969.
27. Terzaghi, K. and Peck, R. B., Soil Mechanics in Engineering Practice,
2d ed., Wiley, New York, 1967.
28. Wu, T. H., Soil Mechanics, Allyn and Bacon, Boston, 1966.
39
-------
29. Calhoun, C. C., "Development of Design Criteria and Acceptance Specifica-
tions for Plastic Filter Cloths," Technical Report S-72-7, Jun 1972,
U. S. Army Engineer Waterways Experiment Station, CE, Vicksburg, Miss.
30. Andersland, 0. B. and Vallee, R. P., "Planning Report on Field Behavior
of an Experimental Pulp and Papermill Sludge Landfill," Sep 1970, Na-
tional Council of the Paper Industry for Air and Stream Improvement, New
York, N. Y.
31. Andersland, 0. B. and Charlie, W. A., "A Cut Slope in Consolidated Paper-
mill Sludge," paper prepared for American Society of Civil Engineers 1975
Geotechnical Engineering Specialty Conference, Raleigh, N. C.
32. Bjerrum, L., "Embankments on Soft Ground," Proceedings, Specialty Confer-
ence on Performance of Earth and Earth-Supported Structures, American
Society of Civil Engineers, 11-1^ Jun 1972, II, 1-5U.
33- Gillespie, W. J., Gellman, I., and Janes, R. L. , "Utilization of High Ash
Papermill Wastes Solids," Proceedings, Second Mineral Waste Utilization
Symposium, Illinois Institute of Technology Research Institute, Chicago,
111., Mar 1970.
3U. Lambe, R. W., Soil Testing for Engineers, Wiley, New York, 1951.
35. Achinger, W. C. and Glar, J. J., "Testing Manual for Solid Waste Incin-
erators," Open Fill Report SW-3TS, 1973, U. S. Environmental Protection
Agency, Washington, D. C.
36. Office, Chief of Engineers, Department of the Army, "Laboratory Soils
Testing," Engineer Manual EM 1110-2-1906, Nov 1970, Washington, D. C.
37. Mitchell, J. E., "Evaluation of Soil Mechanics Laboratory Equipment;
Evaluation of Available Liquid Limit Devices," Miscellaneous Paper
No. 3-H78, Report 3, Apr 1961, U. S. Army Engineer Waterways Experiment
Station, CE, Vicksburg, Miss.
38. Casagrande, A., "Notes on the Design of the Liquid Limit Device,"
Geotechnique, Vol 8, No. 2, Jun 1958, pp 8^-91.
39- Casagrande, A., Hirschfield, R. C., and Poulos, S. J., "Third Progress
Report on Investigation of Stress-Deformation and Strength Characteris-
tics of Compacted Clays," Soil Mechanics Series No. 70, Nov 1963, Harvard
University, Cambridge, Mass.
Uo. "Mercury," Data Sheet 203, National Safety Council, Chicago, 111.
kl. "Design Manual - Soil Mechanics, Foundations, and Earth Structures,"
NAVFAC DM-7, Mar 1971, Naval Facilities Engineering Command, Department
of the Navy, San Bruno, Calif.
-------
ZIO
60 -
DAY
Figure 1. Variability of sludge properties.
-------
LU
o
cr
z
o
o
O
Q
UJ
cc
UJ
Q 10
0 VACUUM FILTER
D CENTRIFUGE
20 30 40 50
SLUDGE ASH CONTENT , PERCENT
Figure 2. Relationship of sludge dewaterability to ash content.
-------
100
90
80
70
Z 60
IxJ
I-
Z
O
0 50
Q
_l
O 40
30
20
0 20 30 40 50 60 70 80
ASH CONTENT , PERCENT
Figure 3- Solids content versus ash content.
90 100
-------
60
50
CO
Q
O 40
a:
a
z
O 30
CD
20
10
BOD
LEGEND
MUNICIPAL REFUSE
HIGH ASH SLUDGE
ALKALINITY
I
CHLORIDE
Figure U. Mass of leachate constituents.
-------
MIN OF 8 FT OR AS NEEDED FOR
CONSTRUCT/ON EQUIPMENT.
-LIMIT SURCHARGE TO
APPROXIMATELY HERE
EXTEND TO
DISCHARGE
FACE
PEA GRAVEL POCKET
EARTH SURCHARGE
\-UPPER DRAINAGE BLANKET
UPPER SLUDGE LAYER
^-MIDDLE DRAINAGE BLANKET
LOWER SLUDGE LAYER
•DRAIN PIPE
AS CONSTRUCTED-
-BOTTOM DRAINAGE BLANKET
Figure 5- Dike and sludge cross section.
-------
6
(3)
5
(2)
3
(3)
^
5
(2)
6
(3)
7
(1)
3
(3)
"N
1
(4)
J
3
(3)
7
(1)
6
(3)
4
(1)
A
2
(2)
r
j
4
(1)
6
(3)
7
(1)
3
(3)
A
i
(4)
V
3
(3)
7
(1)
6
(3)
4
(0
"N
^
2
(2)
r
4
(1)
6
(3)
7
(1)
3
(3)
^
1
(4)
3
0)
7
(1)
6
(3)
5
(2)
J
3
(3)
5
(2;
6
(3)
3.
LEGEND
NUMBERS 1,2,3, ETC. REPRESENT
CONSTRUCTION SEQUENCE.
NUMBERS IN PARENTHESES (1), (2), (3),
(4), REPRESENT THE NUMBER OF EARTH
DIKE SIDES REQUIRED.
"*\- POSSIBLE USE OF MATERIAL IF
DIKES REMOVED.
Figure 6. Plan for landfill.
-------
• SAND BLANKET
EXTEND DIKE AS NEEDED
FOR CONSTRUCTION
THIRD LIFT
SECOND LIFT
AS CONSTRUCTED
THIRD LIFT
SECOND LIFT
FIRST LIFT OF DIKE
- FIRST LIFT OF SLUDGE DUMPED BY TRUCK OR CRANE
LOWER LAYER
NOTE: FIRST, SECOND, AND THIRD LIFTS
OF SLUDGE PLACED BY TRUCK
AND CRANE, DUMPING FROM DIKE
EXTEND DIKE AS NEEDED-
SECOND LIFT
FIRST LIFT OF SLUDGE (UPPER LAYER)
DRAIN PIPES
b. UPPER LAYER
Figure 1. Sludge landfill construction steps.
1*7
-------
Wet density
W
WEIGHT
VOLUME
(wet unit weight) y = ~
i
c
i
>:
i
i
5
1 1
[
D
5
\n
\
AIR
^
— — -
WATER
//////
//////
/SOLIDS/
//^//
\ '
crt
1 1
1 '
^>
i
>•
\ ,
1
Dry density Wg
(dry unit weight) y^' = ~ or
Y
. m
Yd ~ 1 + w
^
1
Ul
] '
Unit weight W _
W x" \ / J
of water Y - ^ - 62.U Ib/ft
w v
w
Submerged or buoyed unit weight
(effective weight of sludge
mass below water table) Y' = ~ - Y or y - 62. \
v w m
W
w
Water content w = rr-
W
s
W
Specific gravity G = TT-^ —
s V y
s w
W
Volume of solids
,r _ S
s G y
s w
Volume of voids V = V - V
Void ratio
e =
V
t
V
Porosity
n =
V
v
V
Degree of saturation
w G
V
. _
' S -
w
1
G
Figure 8. Weight and volume relationships,
1*8
-------
WEIGHT
VOLUME
WATER
y SOLID'
AH
WEIGHT
-------
o
1 FT SAND, 100 PCF
TOTAL VERTICAL
STRESS
HYDROSTATIC
PRESSURE
EFFECTIVE STRESS
IN SLUDGE
;oo
PSF
P0 = Po
Figure 10. Load-depth diagram.
-------
LOAD INCREMENT, AP
inn ni
1 FT SAND, 100 PCF u
O ~
\J
1-
^
N
X
t-
0.
U
Q
1 ^
1 U '
1
y y s y y j '
10 FT SLUDGE ,
y 70 PCF / ^ f
y y y y
- / y y '
y , ,
i j
/ ^
y1 x^ '^
i
-/
* s
y
y ^^ /
i
i
1 FT SAND, 100 PCF
700
AP
PSF
138
PSF
776
AP
A
p
P5F
Figure 11. Load increment added to a sludge layer.
51
-------
ro
I-
Z
LJ
£ °
O £T
LU
LJ Q_
LU
LU
z
o
o
20
40
60
80
00
0.00!
CONSOLIDATION WITH VERTICAL DRAINAGE
INSTANTANEOUS LOADING
NOTATIONS
IMPERVIOUS
ONE-WAY TWO-WAY
DRAINAGE DRAINAGE
0.01 0.1
TIME FACTOR T
Figure 12. Time factors for consolidation analysis,
10
-------
AVERAGE EXCESS PORE WATER
PRESSURE RATIO,-U-, PERCENT
AVERAGE DEGREE OF CONSOLIDATION
U, PERCENT
ELAPSED TIME SUBSEQUENT TO
LOADING YEARS, MONTHS, DAYS
90 T 10
1.00
0.90
0.80
0.70
0.60
0.50 -
0.40 -
0.30 -
0.20 -
0.10
0.09
0.08
0.07
0.06
0.05
0.04 -
0.03 :
0.02 -
0.01 -I
80 - . 20
COEFFICIENT OF
CONSOLIDATION 70
Cw FT2/DAY
- - 30
0
SUPPORT LINE
THICKNESS OF COMPRESSIBLE STRATUM,
FEET, ONE-WAY DRAINAGE
50 - - 50
40 - - 60
30 - - 70
20 - j- 80
1 0 - L 90
5 I 95
100
10
5
4
3
-1- 2
10
9
8
7 •
6-
5
100 - i
50-
(T
<
U
- 1000
I.
2.
TO DETERMINE THE AVERAGE DEGREE OF
CONSOLIDATION AT A GIVEN TIME AFTER
INSTANTANEOUS LOADING-
PASS A STRAIGHT LINE BETWEEN THE
COEFFICIENT OF CONSOLIDATION Cv
(POINT 1) AND THE THICKNESS OF
COMPRESSI BLE STRATUM HAVING ON E-
WAY DRAINAGE (POINT 2) TO ESTAB-
LISH POINT3ON THE SUP PORT LINE.
FROM THE GIVEN ELAPSED TIME
AFTER LOADING (POINT 41 PASS A
STRAIGHT LINE THROUGH POINT 3 TO
OBTAIN POINT 5. THE DESIRED VALUE
OF THE AVERAGE DEGREE OF CON-
SOLIDATION (OR AVERAGE EXCESS
PORE WATER PRESSURE RATIO) IN
PERCENT.
PROCEED IN A SIMILAR MANNER USING
KNOWN DATA TO ESTABLISH UNKNOWN
VALUES, REVISING SEQUENCE OF
OPERATIONS AS REQUIRED.
NOTES:
NOMOGRAPH APPLIES TO ONE-WAY
DRAINAGE OF A STRATUM.
IF COMPRESSIBLE STRATUM HAS TWO.
WAY DRAINAGE USE ONE-HALF OF
STRATUM THICKNESS.
NOMOGRAPH APPLIES TO CASES OF
DOUBLE DRAINAGE WHERE INITIAL
DISTRIBUTION OF EXCESS PORE
WATER PRESSURE IS LINEAR WITH
DEPTH, OR FOR CASES OF SINGLE
DRAINAGE WHERE EXCESS PORE
WATER PRESSURE IS CONSTANT WITH
DEPTH.
5 - -
if!
X
\-
z
o
3500
3000
2500
2000
©
500
- 4OO
- - 300
'- 200
<
D
- 100
50
40
L 30
- 20
Figure 13. Nomograph for consolidation with vertical drainage.
-------
I I I I II
CONSOLIDATION WITH VERTICAL DRAINAGE
GRADUAL CONSTRUCTION LOADING
NOTATIONS:
CONSOLIDATION
DURING CONSTRUCTION
AS PCT COMPLETE
UNDER PORTION OF
LOAD IN PLACE AT
ANY TIME *
END OF
CONSTRUCTION
BEFORE
TIME
0.!
TIME FACTOR T
Figure lU. Time factors for consolidation analysis with gradual load application.
-------
TRIAL ?
5 3
I / 1 / s^TRIAL 4
7 7 7 T 7
SURCHARGE
"/ .Aa
5AND
UPPER
SLUDGE
LAYER
>M
SAND >'.,
LOWER
SLUDGE
LAYER
7 FT i!
SAND LAYER
Figure 15- Slope analysis.
-------
1.2
1.0
0.8
0.6
0.4
20 40 60 80 100 120
PI °70
VANE
Figure l6. Correction factor for converting vane shear
strengths to field shear strengths (22).
-------
+ INSTRUMENT GROUPS
EARTH SURCHARGE LIMIT
BOTTOM SAND BLANKET LIMIT
• ELEVATIONS
Figure 17. Experimental landfill, plan view.
57
-------
v/i
CD
INSTRUMENT GROUP
EARTH SURCHARGE-
INSTRUMENT GROUP 5~
14' OR 20'
EARTH DIKE
UPPER SLUDGE LAYER
(INITIALLY 10' THICK)
70' WIDE GRAVEL DRAIN
(NORTH SIDE ONLY)
LOWER SLUDGE LAYER
(INITIALLY 9.5' THICK)
i
• PIPE
4-
+
-4' WELLPOINT
-8"0 DRAIN PIPE (NORTH SIDE ONLY)
LEGEND
SETTLEMENT PLATES
PIEZOMETERS
£:Q--&;X£ SAND DRAINAGE BLANKETS
' •> GRAVEL
Figure 18. Typical cross section of experimental landfill.
-------
o
I-
cc
Q
O
>
5.0
4.5
4.0
3.5
3.0
2.5
2.0
PO =138 PSF =0.069 T/FT2
en = 4.85
Cc = 1.65
0.05
O.I
0.2
0.4 0.6
0.015
0.2 0.4 0.6 I
, ^
PRESSURE P, T/FT2
Figure 19. Consolidation characteristics of sample
2 3
sludge.
-------
O
LEGEND
SOIL SURCHARGE
SAND BLANKET
SLUDGE
SETTLEMENT PLATE
180
FIELD SETTLEMENT OF LOWER SLUDGE LAYER
210
240
40
Figure 20.
Comparison of predicted and measured time-settlement curves,
lower sludge layer.
-------
30
LU
1/1
<
m
LL|
o 20
m
UJ
IS
O
D
_J
co
u. 10
2
O
I-
UJ
_l
UJ
10
I-
z
Id
2
UJ
_J
[H
CO
20
30 '—
SOIL SURCHARGE
SAND BLANKET
SLUDGE
SETTLEMENT PLATE
TIME, DAYS
THEORY, r =0.0?6 IN. /MIN
FIELD SETTLEMENT OF UPPER SLUDGE LAYER
Figure 21. Comparison of actual and predicted time-settlement curves, upper sludge layer.
-------
1.90 T/M
SAND
SLUDGE
SAND
SLUDGE
SAND
SEPT 7, 1972
94
90
u
LJ
82
78
REMOLDED
UNDISTURBED
0 4 8 12 16 20
VANE SHEAR STRENGTH, T/M2
NOTE: 204.857 x T/M2 = p/FT2
Figure 22. Experimental landfill vane shear strength
immediately before slope excavation.
62
-------
11 FT
1.2
100 PCF
APPROXIMATE
FAILURE ZONE
2 FT
I FT '
7.2 FT
SLUDGE
Y, - 72.6 PCF
SAND X, 100 PCF
M
SLUDGE
>,, - 76.5 PCF
FT
SAND
Figure 23- Cut slope in experimental sludge landfill.
63
-------
6.2 FT
2 FT
CTN
f
/ TRIAL FAILURE
SLIP SURFACE 2
LOWER SLUDGE LAYER
Figure 2U. Cross section of top sludge layer for stability analysis.
-------
TABLE 1. PRIMARY SLUDGE PRODUCTION ASSOCIATED
WITH PAPER MANUFACTURING
,. „ _, , Percentage
Manufacturing Category „ ^ n .
of Production
Unbleached kraft/linerboard 2
Groundwood/newsprint 3-U
Bleached kraft/market pulp paper,
and paperboard 3-k-
Bleached and unbleached paperboard 3-^
Nonintegrated fine paper 2-3
Nonintegrated tissue 2-3
Sulfite pulp and paper 3-^
Integrated groundwood and printing
paper or specialty paper 3-h
Wastepaper board 0-U
Deinking 10-25
TABLE 2. "NORMAL" SLUDGE COMPOSITION
m Consistency Ash Content
Type
Solids, percent percent
Board mills 2-10 50-70
Chemical pulp 1-10 20-50
Deink pulp 3-10 25-60
Groundwood 2-5 1-20
Paper mills 1-5 50-70
65
-------
TABLE 3. PHYSICAL CHARACTERISTICS OF SLUDGES ORIGINATING
IN HIGH ASH SLUDGE LANDFILLS
Mill
A
B
C
D
E
F
>100 Mesh
percent
Range
7-31
k-32
9-3k
11-U8
1-57
3-^6
Average
21.7
11.7
17. U
23.1
30.5
16.1
<100 Mesh
percent
Range
67-99
6k-9k
62-90
52-87
^3-70
51-97
Average
19.k
85.5
80.8
75.6
61.2
81.9
Ash Content
percent
Range
Ul-72
k2-5h
5)4-8)4
35-80
66-91
5U-95
Average
55
U8
6k
62
73
75
TABLE k. FIBRE CLASSIFICATION FOR
SELECTED HIGH ASH SLUDGES
Mill
1
2
3
k
Fraction Retained on
the Indicated Mesh, percent
lU 28
2.k 1.0
3.0 1.7
0.2 0.9
O.k 2.8
k8
13.7
7.1
3.8
9-7
100
<100
15.2 67.7
11.2 76.9
2.3 92.8
8.9 78.2
66
-------
TABLE 5- ANALYSIS OF LEACHATE QUALITY
Sample
Date sampled
COD (mg/£)
BOD (mg/£)
PH
Specific conductance
(pmho/cm)
Turbidity (MTU)
Color (color units)
Total solids (mg/Jl)
Dissolved solids (mg/£.)
Suspended solids (mg/&)
Total iron (mg/&)
Total hardness (mg/£ as
CaCO )
Chloride (mg/£)
I*
10/19/72
9,580
6,6lH
7.6
6,200
56
352
11,786
11,710
76
2.5
6,810
201
II*
11/21/72
H,ooo
2,660
7-7
3,360
13
130
H,960
MHO
120
1.6
3,230
75
III*
12/12/72
H,l60
2,860
7-7
3,100
9
165
5,130
5,100
30
1.5
3,230
70
IV*
12/29/72
H,700
3,250
7.8
6,010
17
H39
9,730
9,570
160
H.3
6,565
206
Vt
2/10/73
7,585
5,158
7.5
H,015
15
187
8,885
7,651
1,23H
3.6
H,310
111
Alkalinity (mg/K, as
CaCO ) 8,670 U,130 U,130 8,770 5,810
Sulfate (mg/£) <1 <1 <1 <1 <1
Total Kjeldahl nitrogen
(mg/£)
Total phosphorus (mg/£)
*Sample extracted from the midsand drainage blanket.
tSample taken from the bottom slope indicator pipe, which is accountable for
the irregular suspended solids concentration.
67
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TABLE 6. TRACE ELEMENTS CONTAINED IN PAPER-MILL PRIMARY SLUDGE
Mill
A
B
C
D
E
F
G
H
Elements, Ib/ton
Cu Zn
14.60
*
—
0.19 0.70
1.60
0.12
0.10
0.20
Pb Hg
0.0)4
*
—
*
0.08 0.09
0.10 0.05
0.20 0.09
0.16 O.lH
Fe Cd
0.80
2.80
H.20
25-50 *
15.20
2.60
13.80 0.02
35.00
Cr
_ —
*
__
0.03
0.08
0.04
o.oU
0.08
Ni
—
—
—
0,03
0.08
0.10
0.02
0.06
Mg
—
*
5.00
0.65
—
—
—
—
*Analysis showed presence of only trace amounts.
TABLE 7. LEACHATE ATTENUATION PROPERTIES OF SOILS
Soil
Type
Sand
Organic
loam
Organic
loam
Clay
Organic
loam
Conditions
Hydraulic
Loadins
,, -, / Aerobic Anaerobic
M gal/
acre/day
6.8 x
6.8 x
6.8 — x
6.8 x
27.0 x
Removals, percent
Dis-
COD solved
Solids
93 58
96 77
85 65
9^ 76
85 U6
Turbidity
91
96
68
68
51
Conductivity
57
80
75
79
IfU
-------
TABLE
PHYSICAL PROPERTIES OF PAPER-MILL SLUDGE
Sludge Sample
No.
L-0
L-l*
L-2*
U-lt
U-2t
U-3t
U-Ut
U-5t
Elevation
in Layer
ft
5
2.5
7-5
2.5
h
5
7.5
10
Consistency
Limits
325.1+-llil.6
257. 3-102.7
2U7.7-105.6
18U.5- 86.0
218.5-101.6
297-5-133.0
287.^-122.1
302.8-138.6
Ash
Content
percent
35-7
U2.2
U3.3
59-^
U6.5
36.5
3^.2
32.2
Solids
Content
percent
by weight
28.5
27.2
28.2
3^.U
31.9
26.9
29.0
28. h
Specific
Gravity
2.01
2.05
2.07
2.2U
2.07
1.91
1.87
1.92
^Average of three samples.
tAverage of three tests per sample location.
Sludge unit weight as placed, y ^70 pcf.
m
Soil surcharge unit weight, y * 130.U pcf.
m
Laboratory test sample locations.
Laboratory test sample locations.
• Sand-;-
\\ Upper sludge layer
: •'.-.•.' Sand •'•. ;. '• •'.•^J/J-
Natural soil
69
-------
20
Z
UJ
2.
Ul
40
o
Z
UJ
2
UJ
_J
t-
Ul
60
in
>
(C
ct
0.
Z
UJ
o
cr
60
IOO
I5
II
TIME , DAYS
Plate 1. Settlement-time plot.
-------
APPENDIX A
METRIC CONVERSION TABLE
Multiply
inches
feet
miles (U. S. statute)
square feet
acres
gallons (U. S. liquid)
pounds (mass)
tons (short)
pounds (force) per
square foot
tons (force) per
square foot
pounds (mass) per
cubic foot
degrees (angle)
Fahrenheit degrees
By
To Obtain
0.025U
0.30U8
1.6093^
0.0929030>4
0.003785^12
0.145359214
907.18U7
147.88026
95.76052
16.018^6
0.017^5329
5/9
metres
metres
kilometres
square metres
square metres
cubic metres
kilograms
kilograms
pascals
kilopascals
kilograms per cubic metre
radians
Celsius degrees or Kelvins'*
*To obtain Celsius (C) temperature readings from Fahrenheit (F) readings,
use the following formula: C = (5/9)(F - 32). To obtain Kelvin (K) read-
ings, use: K = (5/9)(F - 32) + 273.15-
71
-------
APPENDIX B
TESTING PROCEDURES FOR SLUDGE PROPERTIES
Pulp and paper-mill sludges have the physical appearance of clay interr-
woven with cellulose fibers. Depending on the manufacturing processes in-
volved, sludge color varies from gray to brown and consistency varies from
fluid to plastic. A soft plastic material results from dewatering the sludge,
Depending on the method used for dewatering, the solid content ranges from
approximately 1 to 65 percent. The manufacturing and conservation processes
control the solids composition, which generally includes coating and filler
pigments, fibers, and fines. Clay with small amounts of aluminum hydrate,
titanium oxide, lime, and iron compose the fixed solids. The remainder of the
sludge is cellulose, starch, resins, glue, ink, and organic compounds. High
ash sludges have been defined as those which have a fixed solids content of
60 percent or greater (33). As a result of these variations in composition,
sludges can show a wide variation in physical properties and behavior.
As for other materials subjected to engineering purposes and analyses,
knowledge of some of the physical properties of sludges is desired to charac-
terize their behavior. Knowledge of the physical properties of, experience in,
and behavior of the various sludges will lead to better understanding and pre-
diction of their behavior. Based on experience with soil material properties,
the following sludge properties are believed to be important:
a. Solids and water contents.
b. Unit weights.
c. Specific gravity of solids.
d. Consistency limits.
e. Permeability.
f. Ash content and organic content.
g. Physical description of the fibers.
If good and accurate records of the above-mentioned properties are kept,
eventual accumulation of the information should become very valuable in modi-
fying the test procedures in this manual.
At least three of each of the following tests should be conducted per
sludge sample to insure consistency and accuracy of results. Great care
72
-------
should be exercised in obtaining representative sludge samples and in conduct-
ing the test.s_. Sludge samples should be taken and tested every time the manu-
facturing processes change and probably weekly or biweekly. When samples are
taken, they should be stored in airtight containers in a cool place. Airtight
containers prevent loss of moisture and may be glass or plastic jars that seal,
plastic bags, etc. Metal containers are not recommended because of corrosion.
A cool storage atmosphere prevents moisture changes or variation within the
sample due to condensation. A refrigerator will provide cod stoiage.
Test methods for determining sludge properties are given below. Refer-
ences 3^4-36 describe these methods. All methods except those for ash and or-
ganic contents are from Reference 36. The following tests were conducted on
essentially one sludge material (9) and were found to be applicable. However,
because of the wide variation in sludge properties, test methods may have to
be modified on a case-by-case basis. Accumulated records of the various
sludge properties and method modifications will form a basis for changing the
test, methods given below.
SOLIDS AND WATER CONTENTS
Definitions
Solids content, s , is defined as the ratio, expressed as a percentage,
of the weight of solids to the weight of the wet sample.
Water content, w , is defined as the ratio, expressed as a percentage, of
the weight of water in a sample to the weight of the solids.
Apparatus
The test apparatus should consist of the following:
a. Oven, preferably of the forced-draft type, automatically controlled to
maintain a uniform temperature of 85 ± 5°C throughout the oven. (85°C
is suggested for organic soils in Reference 25.)
b. Balances, sensitive to 0.1 g for samples weighing 50 to 500 g and to
1.0 g for samples weighing over 500 g.
c. Specimen containers. Seamless containers with lids are recommended.
The containers should be of a metal resistant to corrosion (aluminum
is satisfactory) or of glass. They should be as small and light in
weight as practicable in relation to the amount of material to be used
in the determination. For routine tests, a minimum sample size should
contain at least 10 g of solids (25).
Procedure
The test procedure is as follows:
a. Record all identifying information for the specimen, such as project
-------
name, sample number, date, manufacturing process, or other pertinent
data, on a data sheet (Plate B-l is a suggested form).
"b. Record the number and tare weight of the specimen container.
c. Place the specimen in the container, set the lid securely in position,
and immediately determine the weight of the container and wet sludge
by weighing on an appropriate balance.
d. Before the specimen is placed in the oven, remove the lid; depending
on the type of container, the lid is usually placed under the con-
tainer in the oven. Then place the specimen and container in the oven
heated to 85 +_ 5°C. Leave the specimen in the oven until it has dried
to a constant weight. The time required for drying will vary depend-
ing on the type of sludge, size of specimen, oven type and capacity,
and other factors. The influence of these factors generally can be
established by good judgment and by experience with the sludges being
tested and the equipment available in the laboratory. When in doubt,
reweigh the ovendried specimens at periodic intervals to establish the
minimum drying time required to attain a constant weight. Depending
on specimen size, two or three days may be required for drying. Dry
specimens may absorb moisture from wet ones; therefore, any dried
specimens must be removed before wet specimens are placed in the oven.
e. After the specimen has dried to constant weight, remove the container
from the oven and replace the lid. Allow the specimen to cool until
the container can be handled comfortably with bare hands. If the
specimen cannot be weighed immediately after cooling it should be
placed in a desiccator; if a sample is left in the open air for a con-
siderable length of time it will absorb moisture.
f. After the specimen has cooled, determine its dry weight and record it
on the data sheet.
Computations
The following quantities are obtained by direct weighing:
a. Weight of tare plus wet sludge, g
b. Weight of tare plus dry sludge, g
The water content in percent of ovendry weight of the sludge is equal to:
(weight of tare plus wet sludge) - (weight of tare plus dry sludge)
(weight of tare plus dry sludge) - (tare)
or
w
w = — x 100 or w = 100 x
W s
s
-------
where w = water content, percent
W = weight of water, g
W = weight of dry solids, g
s = percent of dry solids, percent
The solids content in percent of wet weight of the sludge is equal to:
(weight of tare plus dry sludge) - (tare)
(weight of tare plus wet sludge) - (tare)
or
¥s n nn 100
s = 7— x 100 or s =
w
loo + -
where W = total wet specimen weight, g
Possible Errors
Following are possible errors that would cause inaccurate determinations
of solids and water contents:
a.. Specimen not representative. The specimen must be representative of
the sample as required for determination purposes. For example, tc
determine average water content of a sludge, the specimen must be
large enough to contain representative amounts of all constituents.
b. Specimen too small. As a rule, the larger the specimen, the more ac-
curate the determination because of the larger weights involved.
c. Loss of moisture before weighing wet specimen. Even in a covered con-
tainer a specimen can lose a significant amount of water unless
weighed within a short period.
d. Incorrect temperature of oven. The ovendry weight of many sludges is
dependent on the temperature of the oven, so variations in temperature
throughout the interior of an oven can cause large variations in the
computed solids and water content (3M-
e. Specimen removed from oven before obtaining a constant ovendry weight.
f. Gain of moisture before weighing ovendry specimen.
g. Weighing ovendry specimen while still hot. The accuracy of a sensi-
tive balance may be affected by a hot specimen container -
h. Incorrect tare weight. The weights of specimen containers should be
checked periodically and should be scratched on the containers to
avoid possible errors in reading such weights from lists.
75
-------
UNIT WEIGHTS
Two methods for determining unit weights are presented in the following
paragraphs—displacement and volumetric. The displacement method should be
used for the plastic-type sludges that can support themselves in uncontained
mounds. The volumetric method should be used for the fluid-type sludges.
Definitions
Wet unit weight, ym , or wet density, is the weight (solids plus water)
per unit of total volume of sludge. The wet unit weight is usually expressed
in pounds per cubic foot.
Dry unit weight, Yd » or ^y density, is the weight of ovendried sludge
solids per unit of total volume of sludge, and is usually expressed in pounds
per cubic foot.
Volumetric Method
The volumetric method is described below.
Apparatus--
The apparatus should consist of the following:
a. A volumetric container of known volume and as large as possible in re-
lation to the constituents of the sludge being tested. The container
should be of materials not susceptible to corrosion such as seamless
aluminum or glass with lids.
b. The same type of oven and balance as those for solids and water con-
tent determinations.
Procedure—
The procedure is as follows.
a. Record on a data sheet (Plate B-2 is a suggested form) all identifying
information for the sludge sample.
b. Determine and record the volumetric container weight in grams.
c. Fill the volumetric container' with the fluid-type sludge and strike
off the top evenly. Weigh the container plus wet sludge and record
the weight.
d. Place the sludge and container in the oven and dry it as described for
the solids and water content determinations. Obtain and record the
weight of the container plus dry sludge.
C omput at i o n s —
The following quantities are obtained in the test.
a. Weight of tare (volumetric container) plus wet sludge. The tare
76
-------
weight is subtracted from this value to obtain the weight of wet
sludge, W .
b. Weight of tare plus dry sludge. The tare weight is subtracted from
this value to obtain the weight of dry sludge, ¥s , or an alternate
procedure is dry weight of specimen computed by the following equation :
TT wet weight of specimen W
w — - - ^— - = — --
s water content of specimen 1 + 0 . Olw
100
c. The inside volume of the volumetric container. Volume V of the wet
sludge specimen is equal to this volume.
d. Wet unit weight, ym , and dry unit weight, j^ •> expressed in terms
of pounds per cubic foot, are computed by the following equations:
= weight in g of wet specimen
m volume in cc of wet specimen
x 62 ^ = W
'
V
x
W
= weight in g of dry specimen x ^^ = _§. x g2.U
d volume in cc of wet specimen ' V
Displacement Method
Apparatus—
The apparatus should consist of the following:
a. Wire basket of sufficient size to contain the sludge specimen.
b. Can, or container, of sufficient size to submerge the wire basket and
specimen.
c. Specimen container. The container should be of materials not suscep-
tible to corrosion such as seamless aluminum or glass with lids.
d. Paintbrush.
e. Microcrystalline wax or paraffin.*
f. Container for melting wax, preferably with a self-contained thermostat.
*Among the many microcrystalline waxes found satisfactory are Product 2300
of the Mobile Oil Company, Microwax T5 of the Gulf Oil Corporation, and
Wax 1290 of the Sun Oil Company. Paraffin alone is not as suitable for
sealing sludge specimens because its brittleness and shrinkage upon cooling
will cause cracking, especially in thin sections and at corners; a mixture
of 50 percent paraffin and 50 percent petrolatum has properties that ap-
proach those of a microcrystalline wax (36).
TT
-------
g. Thermometer, range 0 to 50°C, graduated in 0.1 deg.
h. The same type of oven and balance as those for solids and water_con-
tent determinations.
i. A hobby tool with a high-speed rotating circular saw (preferably about
3/^-in.-diameter saw blade).
Procedure—
The procedure is as follows:
a. Record on a data sheet (Plate B-3 is a suggested form) all identifying
information for the sludge sample.
b. Determine, if not previously established, the specific gravity of the
wax to be used. (About 0.9 g per cm2, but it should be determined for
each batch of wax.)
c. Cut a specimen from the sample to be tested. (The size of the speci-
men is not very important provided the capacity of the balance is not
exceeded. In general, more accurate results will be obtained with
larger specimens.) Carefully trim the specimen to a fairly regular
shape. The circular saw hobby tool is recommended for trimming be-
cause of the sludge fibers. Re-entrant angles should be avoided, and
any cavities formed by large particles being pulled out should be
patched carefully with material from the trimmings.
d. Determine and record the wet weight of the sludge specimen.
e. Cover the specimen with a thin coat of melted wax, either with a
paintbrush or by dipping the specimen in a container of melted wax.
Apply a second coat of wax after the first coat has hardened. The wax
should be sufficiently warm to flow when brushed on the sludge speci-
men, yet it should not be so hot that it penetrates the pores of the
sludge. If hot wax comes in contact with the specimen it may cause
the moisture to vaporize and form air bubbles under the wax.
f. Determine and record the weight of the wax-coated specimen in air.
g. Determine and record the submerged weight of the wax-coated specimen.
This is done by placing the specimen in a wire basket hooked onto a
balance and immersing the basket and specimen in a can of water as
shown in Figure B-l. In order to directly measure the submerged
weight of the wet sludge and wax, the balance must have been previ-
ously balanced with the wire basket completely submerged in the can of
water. Insure that the specimen is fully submerged, and that the
basket is not touching the sides or bottom of the container. Measure
the temperature of the water.
h. Remove the wax from the specimen. It can be peeled off after a break
is made in the wax surface. Use the entire sample, or as much as is
free of wax inclusions, for a water content determination.
78
-------
Computations —
The following quantities are obtained directly in the test:
a. Weight of uncoated specimen, ¥ ,
b. Weight of sludge plus wax. The weight of uncoated specimen, V , is
subtracted from this value to obtain the weight of wax.
c, Weight of sludge plus wax in water.
The following computations will be made:
a. Divide the weight of the wax by its specific gravity. This gives the
volume of the wax.
b. Subtract the weight of the wax-coated specimen in water from its
weight in air- The difference divided by the density of water at the
test temperature (see Table B-l) is numerically equal to the volume of
the coated specimen in cubic centimeters,
c. Subtract the volume of wax from the volume of the coated specimen to
obtain the total volume of the sludge specimen, V .
d. Compute the water content of the specimen. If the entire specimen is
used for the water content determination, obtain the dry weight of
specimen, Ws , directly. If only a portion of the initial specimen
is used for the water content determination, compute the dry weight of
specimen according to the following equation:
w _ wet weight of uncoated sludge _ W
s _, , water content of wet sludge ., w
100 100
Based on the information above, compute the unit weights as specified
hereinbefore.
Possible Errors
Following are possible errors that would cause inaccurate determinations
of the total volume:
Volumetric Method—
a. Imprecise measurement of volumetric cylinder. Three height measure-
ments and nine diameter measurements should be made to determine the
average height and diameter of the cylinder. Precise calipers should
be used for these measurements rather than flat scales.
b. Imprecise weight measurements.
Displacement Method—
Voids on surface of specimen not filled by wax or air bubbles formed be-
neath wax.
79
-------
SPECIFIC GRAVITY
Definition
The specific gravity of solids, Gs , of a sludge is the ratio of the
weight in air of a given volume of solids at a stated temperature to the
weight in air of an equal volume of distilled water at a stated temperature.
Apparatus
The apparatus should consist of the following:
a. Volumetric flask, 500-cm^ capacity or larger.
b. Vacuum pump, with piping and tubing for connections to each flask (as
shown in Figure B-2). The connection to each flask should be provided
with a trap to catch any water drawn from the flask.
c. Thermometer, range 0 to 50°C, graduated in 0.1 deg.
d. Evaporating dish.
e. Water bath.
f. The same type of oven and balance as those for solids and water con-
tent determinations.
Calibration of Volumetric Flask
The volumetric flask will be calibrated for the weight of the flask and
water at various temperatures. The flask and water are calibrated by direct
weighing at the range of temperatures likely to be encountered in the labora-
tory. The calibration procedure is as follows:
a. Fill the flask with deaired-distilled (or deaired-demineralized) water
to slightly below the calibration mark and place in a water bath which
is at a temperature between 30 and 35°C. Allow the flask to remain in
the bath until the water in the flask reaches the temperature of the
water bath. This may take several hours. Remove the flask from the
water bath, and adjust the water level in the flask so that the bottom
of the meniscus is even with the calibration mark on the neck of the
flask. Thoroughly dry the outside of the flask and remove any water
adhering to the inside of the neck above the graduation; then weigh
the flask and water to the nearest 0.01 g. Immediately after weighing,
shake the flask gently and determine the temperature of the water to
the nearest 0.1°C by immersing a thermometer to the middepth of the
flask.
b. Repeat the procedure outlined in step a at approximately the same
temperature. Then make two more determinations, one at room tempera-
ture and the other at approximately 5 deg less than room temperature.
-------
c. Draw a calibration curve showing the relation between temperature and
corresponding weights of the flask plus water. Prepare a calibration
curve for each flask used for specific gravity determinations and
maintain the curves as a permanent record. A typical calibration
curve (omitting the fine grid necessary for accurate determinations)
is shown in Figure B-3.
Preparation of Sample
Particular care should be taken to obtain representative samples for deter-
mination of specific gravity of solids. The sample of sludge should be at its
natural water content, because sludges with high organic content would be dif-
ficult to rewet after having been oven-dried.
Procedure
The procedure for determining the specific gravity of sludges at natural
water content is as follows.
a. Record all identifying information for the sample, such as project
name, sample number, and other pertinent data, on a data sheet (see
Plate B-^4 for suggested form).
b. Place a representative sample of sludge equivalent to approximately
50 to 80 g (or greater depending on the size of sludge constituents)
ovendry weight in a dish and, by means of a spatula, mix with suffi-
cient distilled or demineralized water to form a slurry, if it is not
already a slurry. Place the slurry in a volumetric flask and fill the
flask approximately half full with distilled water.
c. Connect the flask to the vacuum line as shown in Figure B-2 and apply
a vacuum of approximately 29-0 in. of mercury. Agitate the flask
gently at intervals during the evacuation process; commercially
available mechanical agitators may be used for this purpose. The
length of time that vacuum should be applied will depend on the type
of sludge being tested. The process probably will require 6 to 8 hr;
some sludges may require less time for removal of air but this should
be verified by experimentation. To insure continuous boiling, the
temperature of the flask and contents may be elevated somewhat above
room temperature by immersing in a water bath at approximately 35°C.
Additionally, entrapped air* should be removed by boiling** the
suspension gently for at least 30 min while occasionally rolling the
flask to assist in the removal of air. The boiling process should be
observed closely as loss of material may occur. Allow flask and con-
tents to cool, preferably overnight, before filling and checking.
*Air removal from organic sludges usually cannot be accomplished by the ap-
plication of vacuum. Therefore, it will be necessary to boil the suspen-
sion contained in the flask for about 30 min, adding distilled or deminer-
alized water carefully from time to time to prevent boiling the sample dry.
The flask should at all times be approximately half full.
**Use of indirect heat such as a sand bath is recommended.
81
-------
d. Fill the flask with deaired distilled water to about 3 A in. below the
graduation and apply a vacuum slightly less than that which will cause
vigorous boiling (as vigorous boiling may result in a loss of solids).
To determine if the suspension is deaired, slowly release the vacuum
and observe the lowering of the water surface in the neck of the flask.
If the water surface is lowered less than 1/8 in., the suspension can
be considered sufficiently deaired.
e. Fill the flask until the bottom of the meniscus is coincident with the
calibration line on the neck of the flask. Thoroughly dry the outside
of the flask and remove the moisture on the inside of the neck by wip-
ing with a paper towel. Weigh the flask and contents to the nearest
0.01 g. Immediately after weighing, stir the suspension to assure uni-
form temperature, and determine the temperature of the suspension to
the nearest 0.1°C by immersing a thermometer to the middepth of the
flask.
f. Carefully transfer the contents of the flask to an evaporating dish.
Rinse the flask with distilled water to insure removal of all of the
sample from the flask. Oven-dry the sample to a constant weight at a
temperature of 85 +_ 5°C. Allow the sludge to cool to room temperature
in a desiccator and determine the weight of the sludge to the nearest
0.01 g.
g. Record all weights on the data sheet.
Computations
The following quantities are obtained by direct weighing:
a. Weight of flask + water + solids at test temperature = W-j-^g in grams.
b. Weight of tare plus dry sludge in grams. The tare weight is sub-
tracted from this value to obtain the weight of dry sludge, Ws . The
specific gravity of solids is computed to two decimal places by the
equation:
W K
G =
s ¥ + W, - W
s bw bws
where K = correction factor based on the density of water at 20°C
(see Table B-l). Unless otherwise required, specific
gravity values reported shall be based on water at 20°C.
W = weight of flask plus water at test temperature in grams
(obtained from calibration curve as shown in Figure B-3
Possible Errors
Following are possible errors that would cause inaccurate determinations
of specific gravity:
82
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a. Imprecise weighing of flask and contents. Since the computation of
the specific gravity of solids is based on a difference in weights
which is small in comparison with the weights themselves, the same bal-
ance should be used for calibrating the volumetric flask and for de-
termining the specific gravity whenever the calibration curve is used.
b. Temperature of flask and contents not uniform. Both in calibrating
the flask and determining the specific gravity, utmost care should be
taken to insure that measured temperatures are representative of the
flask and contents during the times when the weighings are made.
c. Flask not clean. The calibration curve will not remain valid if dirt
accumulation changes the weight of the flask. Also, if the inside of
the neck is not clean, an irregular meniscus may form.
d. Moisture on outside of flask or inside of neck. When calibrating the
flask for a temperature lower than room temperature, there is a
tendency for condensation to form on the flask despite careful drying
and rapid weighing. Whenever possible, weighing should be done at
approximately the same temperature as that of the flask.
e. Meniscus not coincident with mark on neck of flask. One drop of water
too much makes an error of approximately 0.05 g- This error can be
minimized by taking the average of several readings at the same tem-
perature. When the suspension is opaque, a strong light behind the
neck is helpful in seeing the bottom of the meniscus.
f. Use of water containing dissolved solids. It is essential that dis-
tilled or demineralized water be used exclusively to insure the con-
tinued validity of the flask calibration curve.
g. Incomplete removal of entrapped air from sludge suspension. This is
the most serious source of error in the specific gravity determination
and will tend to lower the computed specific gravity. The suspension
must be thoroughly evacuated or boiled and the absence of entrapped
air verified as described in Procedure. (it should be noted that air
dissolved in the water will not affect the results, so it is not
necessary to apply vacuum to the flask when calibrating or after fill-
ing the flask to the calibration mark.)
CONSISTENCY LIMITS
The consistency limits are water contents that define the limits of the
various stages for a given sludge. The principal stages from an engineering
standpoint are shown in Figure B-^. The liquid limit (LL) and the plastic
limit (PL) define the upper and lower limits, respectively, of the plastic
range of a sludge; the numerical difference between these two limits expresses
the plasticity of a sludge and is termed the plasticity index (Pi). The
shrinkage limit (SL) defines the lower limit of the semisolid range of a
sludge. Detailed procedures for determining the liquid and plastic limits are
given below, and a detailed procedure for determining the shrinkage limit is
83
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also given. Sludges containing a large percentage of fibres will not easily
lend themselves to the consistency tests. When the fibres interfere with the
test procedures, this fact should be noted.
Liquid Limit Test
Definition—
The liquid limit of a sludge is the water content, expressed as a percent-
age of the weight of ovendried sludge, at which two halves of a sludge pat
separated by a groove of standard dimensions will close at the bottom of the
groove along a distance of 1/2 in. under the impact of 25 blows in a standard
liquid limit device.
Apparatus—
The apparatus should consist of the following:
a. Liquid limit device, as shown in Figures B-5 and B-6, having a crank
and cam to lift and then drop a brass cup onto a block of resilient
material. A motorized liquid limit device may be used, provided that
it meets the specifications of the conventional device and that vibra-
tion is imperceptible during operation. However, comparative tests
should be performed to insure that the motorized device gives the same
results as those obtained using the conventional device. Several de-
tails in the construction of the liquid limit device are of particular
importance. First, the material of the base will be Micarta Wo. 221A
or a hard rubber of equal dynamic resiliency. A 5/l6-in.-diameter
steel ball bearing dropped from a height of 10 in. above the top of
the base will rebound at least 7-3 in. but not more than 9 in. for a
base to be satisfactory. The top of the base will be well polished,
and rubber feet are necessary to eliminate the influence of the sup-
porting table. The cam will be shaped so that the height of the cup
is maintained constant for a short section at the end of the turn
rather than rising continuously to the point of release (37)- The
weight of the cup with the cam follower will be 175 ±15 g.* Fig-
ures B-5 and B-6 show the cup supported by a pin made integral with
the cam follower; however, a separate pin may be used to support the
cup provided there is assurance that the cup will always be removed
from the support for shaping and grooving the soil pat (38).
b. Grooving tool, conforming in general to the dimensions shown in Fig-
ure B-5. The critical dimensions of the grooving tool are those which
govern the shape and depth of the sludge groove. The gage for check-
ing height of drop of the cup will be 10 +_ 0.2 mm (0.39^ +_ 0.008 in.).
The shape of the gage may vary, depending on the manufacturer, but it
should have a square edge, not round.
c. Spatula, having a blade about U in. long and about 3A in. wide.
d. Mixing dish or bowl.
^Material is not to be added to the cup to meet this requirement,
Qh
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e. Specimen containers. Seamless metal or glass containers with lids are
recommended. The containers should be resistant to corrosion.
f. The same types of balance and oven as those for solids and water con-
tent determinations.
Check and Adjustment of Liquid Limit Device—
Periodically, the following points will be checked.
a. The cam will be shaped so that the last 1/8 in. of movement along the
cam before the cup drops will cause no change in elevation of the cup.
b. The pin on which the cam follower rests should not be worn suffi-
ciently to permit sideplay.
c. The screws connecting the cup to the cam follower will be tight.
d. A groove should not have been worn in the cup to the extent that it
can be felt distinctly by hand. If so, the cup will be replaced.
e. When, at the point of contact between the cup and the base, either a
dent in the base or a flat on the cup can be felt distinctly by hand,
the worn item will be replaced or repaired. A worn cup can be
remedied by moving the cam follower to obtain a new point of impact.
A dent in the base can be eliminated by removing a thin layer and
repolishing.
f. The grooving tool will be inspected to insure that the dimensions
controlling the groove in the sludge are as shown in Figure B-5. The
grooving tool will be replaced when the width of the tip exceeds
2.1 mm (0.083 in.) or is less than 1.9 mm (0.075 in.).
g. The height of drop of the cup will be adjusted as follows: By means
of the gage on the handle of the grooving tool and the thumbscrew at
the rear of the device, adjust the height to which the cup is lifted
so that the point on the cup that comes in contact with the base (not
the lowest point of the cup) is 10 +_ 0.2 mm (0.391* ± 0.008 in.) above
the base, as shown in Figure B-5. Secure the adjustment by tightening
the thumbscrew on top of the device and then recheck the adjustment.
A flashlight is helpful in making this critical adjustment.
Preparation of Material—
Material will be selected and prepared as follows.
a. It is essential that the same carefully prepared sludge mixture be
used for determining both the liquid and plastic limits. Sludges of
different plasticity will not be mixed. Furthermore, if the natural
water content is to be determined, the specimen will be taken from an
identical mixture to permit valid correlations. If other test results
are to be correlated with the liquid and plastic limits, the material
used for the determinations will be the same as that tested.
85
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b. Whenever possible, sludges will be at the natural water content when
preparation for testing is begun. If drying has occurred before test-
ing, the limit values may change. The plasticity of sludges contain-
ing significant organic content may be highly sensitive to drying.
The effects of drying can be determined by comparing the liquid limit
values of specimens in "undried," "airdried," and "ovendried" states.
c. Samples will be of sufficient size to produce 150 to 200 g of material.
This amount will also provide enough material for performing the plas-
tic limit test. The sample material will be mixed thoroughly with
distilled or demineralized water until it has a water content some-
what above the liquid limit (a consistency requiring between 15 and
20 blows to cause closure of the groove); with experience it becomes
possible to judge very closely when this condition is reached. The
mixture will be covered with an airtight lid and left at least over-
night, and preferably for 2U hr, and then remixed thoroughly.
Procedure—
The liquid limit test procedure is as follows:
a. Record all identifying information for the specimen, such as project
name and other pertinent data, on a data sheet (Plate B-5 is a sug--
gested form).
b. Place 50 to 80 g of the thoroughly mixed specimen in the brass cup and
level it off to a depth of approximately 1 cm. Divide the sludge in
the cup with the grooving tool so that a clean, sharp groove is formed,
as shown in Figure B-T- When making the groove, hold the cup in the
hand with the cam follower upward and draw the grooving tool, beveled
edge forward, through the specimen, downward away from the cam fol-
lower. The grooving tool should always be held perpendicular to the
cup at the point of contact, as shown in Figure B-7- With sludges
containing a large amount of organic matter it may not be possible to
draw the grooving tool through the specimen without tearing the sides
of the groove. In such cases the groove may possibly be made with a
sharp spatula, using the grooving tool only for final checking of the
groove.
c. Connect the cup to the device and turn the crank at a rate of two
revolutions per second. Count the blows until the two halves of the
sludge pat come in contact at the bottom of the groove along a dis-
tance of 1/2 in. as shown in Figure B-8. Record on the data sheet
the number of blows required to close the groove.
d. Remove 5 to 10 g of sludge from the portion of the sludge pat which
flowed together, and place it in a specimen container. Determine the
water content of the specimen in accordance with the procedures for
solids and water content determinations. All weighing will be accu-
rate to 0.01 g, and water contents in percent will be computed to
one decimal place.
e. Transfer the sludge remaining in the cup to the mixing dish. Wash and
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dry the cup and grooving tool and repeat steps b, c, and d for three
additional portions of the specimen for which the water content has
"been adjusted by drying. Drying may be accomplished by continued mix-
ing with a spatula, aided, if desired, by a small electric fan. The
water content adjustment for each portion will be sufficient to pro-
duce a noticeable variation in the number of blows required to close
the groove. The object of this adjustment is to vary the number of
blows required to close the groove from below 25 to above 25, though
preferably from not less than 15 to not more than 35. It is recom-
mended that the water content of two portions be adjusted to require
between 15 and 25 blows and of two others to require between 25 and
35 blows. Material remaining in the mixing dish will be preserved for
the plastic limit test.
Computations—
Computations will be made as follows.
a. After all necessary data have been recorded on the data sheet, compute
the water content of each specimen as follows:
,, . , , weight of water , __
water content, percent = ;———5 —:— —; x 100
weight of ovendried sludge
b. Determine the liquid limit from a plot of water content versus number
of blows on a semilogarithmic graph. Plot water content on an arith-
metic scale (ordinate) and plot the corresponding number of blows on a
logarithmic scale (abscissa) as shown in Plate B-5- The best straight
line (called the "flow line") is drawn through the four plotted points.
The liquid limit is the water content corresponding to the intersec-
tion of this straight line and the 25-blow line on the graph. Record
the liquid limit to the nearest 0.1 percent water content but omit the
percent designation. However, the final results may be reported to
the nearest whole number.
Plastic Limit Test
Definition—
The plastic limit of a sludge is the water content, expressed as a per-
centage of the weight of ovendried sludge, at which the sludge begins to
crumble when rolled into a thread 1/8 in. in diameter.
Apparatus—
The apparatus will consist of the following:
a. Surface for rolling the thread, such as a fine-ground glass plate or a
smooth tabletop of linoleum or dense, fine-grained wood. Clean, white
paper may be placed on the surface for rolling provided the type of
paper will not result in accumulations of lint in the specimen.
b. Spatula, having a blade about U in. long and about 3A in. wide.
87
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c. Specimen containers, of the type used for the liquid limit test
procedure.
d. Balance and oven of the types used for liquid limit test, sensitive to
0.01 g.
Preparation of Material—
The material to be used for the plastic limit test will be taken from the
same carefully prepared mixture used for the liquid limit test, as described
previously. Approximately 20 g of material is required for the plastic limit
test.
Procedure—
The procedure will consist of the following steps:
a. Record all identifying information for the specimen on the data sheet
(Plate B-5).
b. Take 2 to 5 g of the material remaining from the liquid limit test.
The material will be taken at any stage of the drying process at which
the mass becomes plastic enough to be shaped into a ball easily with-
out sticking to the fingers when squeezed.
c. Shape the specimen into an ellipsoidal mass and roll it either under
the root of the fingers, under the palm of the hand, or under the heel
of the thumb and against the surface for rolling. Use just enough
pressure to roll the sludge mass into a thread 1/8 in. in diameter as
shown in Figure B-9.* When the diameter of the thread becomes 1/8 in.
without crumbling, fold and knead the thread into a ball again and re-
peat the rolling process. Continue kneading and rolling the specimen
until the sludge has dried to the point at which the rolled thread
will break into numerous pieces with a diameter of 1/8 in. and lengths
of about 1/8 to 3/8 in. (39), as shown in Figure B-10.
d. Place the pieces of the crumbled thread into a specimen container and
determine the water content. Repeat steps b and c with another por-
tion of the prepared material in order to check the plastic limit.
The plastic limit will be reported as the average of the two tests if
the two test values vary not more than 5 percent from the average;
otherwise, the test will be repeated.
e. Record all weights and computations on the data sheet. All weighing
should be accurate to 0.01 g, and water contents in percent computed
to one decimal place.
Computations—
Computations will be made as follows.
a. After all necessary data have been recorded on the data sheet, compute
the plastic limit of each specimen as follows:
*The pressure required for rolling the thread will vary greatly depending on
the toughness of the sludge.
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„, . . , . . . weight of vater
Plastic limit = . , , &f , . , — x 100
weight of ovendried soil
b. Compute the plasticity index as follows.
Plasticity index = liquid limit - plastic limit
PI = LL - PL
Possible Errors—
Possible errors that would cause inaccurate determinations of the liquid
and plastic limits are listed below.
General—
a. Specimen not representative. As described previously, the liquid and
plastic limits must be determined using the same mixture of sludge as
that used for determinations of natural water content or for other
tests.
b. Specimen improperly prepared. The specimens must be thoroughly mixed
and be permitted to cure for a sufficient period before testing. Er-
roneous results may be caused by testing airdried or ovendried sludges
c. Inaccurate determination of water contents. The possible errors de-
scribed under solids and water content determinations would greatly
affect the computed liquid and plastic limits because of the small
quantities of material available for the water content determinations.
d. Computational mistakes.
Liquid Limit Test—
a. Improperly constructed or adjusted liquid limit device.
b. Worn parts of liquid limit device, especially at point of contact be-
tween the cup and the base, or worn tip of grooving tool.
c. Sludge at point of contact between the cup and the base. Removal of
the cup for shaping and grooving the sludge pat will also insure that
the bottom of the cup and the top of the base are clean. Any sludge
that has dropped onto the base can be removed with one stroke of the
back of the hand just before replacing the cup.
d. Loss of moisture during test.
e. Large percentage of fibres.
Plastic Limit Test—
a. Rolling thread under fingers. The fingers will break the thread
prematurely.
b. Incorrect final thread diameter. A length of 1/8-in.-diameter metal
rod close at hand will help in estimating this diameter accurately.
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c. Stopping the rolling process too soon. If there is any doubt as to
whether the thread has crumbled sufficiently, it is better to roll the
thread once more than to stop the process too soon.
Shrinkage Limit Test
Definition—
The shrinkage limit of a sludge is the water content, expressed as a per-
centage of the weight of the ovendried sludge, at which further loss in mois-
ture will not cause a decrease in its volume. As part of the shrinkage limit
test, the shrinkage ratio R and linear shrinkage Ls are also usually de-
termined. The shrinkage ratio is defined as the ratio between a given volume
change and the corresponding change in water content above the shrinkage limit.
The linear shrinkage is defined as the decrease in one dimension of a sludge
mass, expressed as a percentage of the original dimension, when the water con-
tent is reduced from a given value to the shrinkage limit.
Apparatus—
The apparatus should consist of the following:
a. Evaporating dish; a porcelain evaporating dish approximately U-l/2 in.
in diameter is recommended.
b. Shrinkage dish; a circular porcelain or monel metal dish 1-3A in. in
diameter and 1/2 in. in height may be sufficient.
c. Glass cup, about 2 in. in diameter and about 1 in. in height with the
top rim ground smooth and flat.
d. Glass plate, 3 by 3 by l/l6 in. fitted with three metal prongs for
immersing the sludge pat in mercury as shown in Figure B-ll.
e. Mercury, sufficient to fill the glass cup to overflowing.
f. Spatula, having a blade about h in. long and about 3 A in. wide.
g. Steel straightedge.
h. Balances and oven same as those for liquid limit tests.
Preparation of Materials—
Approximately 30 g of sludge will be obtained from the thoroughly mixed
portion of the material. The material to be used in the test should be pre-
pared in the same manner as that described for the liquid limit test.
Procedure—
The procedure is as follows.
a. Record all identifying information for the specimen on a data sheet;
see Plate B-6 for suggested form.
b. Place the specimen in the evaporating dish and mix it thoroughly with
distilled water. The amount of water added will be sufficient to make
90
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the sludge wet enough to be readily vorked into the shrinkage dish
without inclusion of air bubbles. The amount of water required to
give sludge the desired consistency is equal to or slightly greater
than the liquid limit.
c. Coat the inside surface of the shrinkage dish with a thin layer of
petroleum jelly or similar compound to prevent the sludge from adher-
ing to the dish. Place an amount of the wetted sludge equal to about
one-third the volume of the dish in the center of the dish and tap the
dish on a firm surface, causing the sludge to flow to the outer edges.
Continue tapping the dish until all air bubbles are eliminated from
the sludge. Repeat this step for two more layers. The final layer
will fill the dish completely, with some excess sludge allowed to
stand above the rim of the dish. Strike off the excess sludge with a
straightedge and remove all sludge adhering to the outside of the dish.
d. Weigh the full dish of sludge immediately and record the weight on the
data sheet as the weight of dish and wet sludge. Allow the sludge pat
to air-dry until a definite color change takes place and then oven-dry
to a constant weight. Record the ovendried weight as the weight of
the dish and dry sludge. Determine and record the weight of the empty
dish.
e. Determine the volume of the shrinkage dish by filling the dish to
overflowing with mercury,* removing the excess by pressing a glass
plate firmly over the top of the dish, and weighing the amount of mer-
cury required to completely fill the dish. The weight of the mercury
divided by its density (13-53 g per cm3) equals the volume of the in-
side of the shrinkage dish. Record the volume of the shrinkage dish,
which is equal to the volume of the wet sludge pat.
f. Place the glass cup in the evaporating dish and fill it with mercury
to overflowing. Remove the excess mercury by placing the glass plate
with the three metal prongs firmly over the cup; take care not to trap
air under the plate. Empty the excess mercury from the evaporating
dish and remove all mercury adhering to both the glass cup and the
evaporating dish with a brush.
g. Determine the volume of the sludge pat by immersing the pat in the
mercury contained in the cup, using the glass plate with the three
metal prongs as shown in Figure B-ll. Take care not to trap air under
the sludge pat or glass plate. Determine the weight of the displaced
mercury and compute its volume, as indicated in step e above, and re-
cord it as the volume of the dry sludge pat.
h. Record all information pertaining to the sludge specimen such as
weights, volumes, etc., on the data sheet, Plate B-6.
*Caution should be exercised in handling mercury. Mercury may have toxic
effects, particularly if spilled on the floor in areas without good venti-
lation. See Handling of Mercury below.
91
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Computations —
Water Content — The water content w of the sludge at the time it was
placed in the shrinkage dish is determined as follows:
W
w = r^ x 100
W
s
where W = weight of water in g , obtained by subtracting the weight of the
W shrinkage dish plus dry sludge from the weight of the dish plus
wet sludge
W = weight of ovendried sludge in g , obtained by subtracting the
3 weight of the shrinkage dish from the weight of the dish plus dry
sludge
Shrinkage Limit — The shrinkage limit, SL, is calculated as follows:
/V - V \
SL = w - — - - * 100
where SL = shrinkage limit
w = water content of wet sludge pat when placed in shrinkage dish, ex-
pressed as a percentage of the weight of ovendried sludge
V = volume of wet sludge pat, cirP
weight of displacement mercury in evaporating dish
s specific gravity of mercury (13.53 g per cm3)
= volume of ovendried sludge pat, cm^
W = weight of ovendried sludge pat, g
S
Shrinkage Ratio — The shrinkage ratio E will be determined by the fol-
lowing equation:
W
where Ws and Vs are the same as given above.
Linear Shrinkage — The linear shrinkage Ls will be determined by the fol-
lowing equation:
L = 100
s
L 3/_J£0_\
I1 ~ \c + 100 y
where C = volumetric change from a given water content w (usually LL)
C = (w - SL)R
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Possible Errors —
Besides errors in the preparation of sludge mixtures given under Liquid
and Plastic Limits, following are possible errors that would cause inaccurate
determinations of shrinkage limit:
a. Inside of shrinkage dish not lubricated. If the sludge adheres to the
shrinkage dish, the sludge pat may crack during drying.
b. Air bubbles included in sludge pat.
c. Sludge pat dried too rapidly. To prevent the sludge pat from cracking,
it should be dried slowly, first in the humid room and then in the air
of the laboratory, until a definite change in color is noted. Only
then should it be placed in the oven.
d. Air bubbles trapped beneath sludge pat or glass plate when immersing
pat in mercury.
Handling of Mercury
Properties — Mercury is an odorless silver-white liquid at normal tempera-
ture and pressure. Mercury has the property of forming amalgams with most
metals, with the exception of platinum and iron. It is highly volatile,
vaporizing at room temperature to form vapors that are highly toxic. Mercury
has a specific gravity of 13.6, a boiling point of 356. 9°C, and a freezing
point of -38.9°C.
Health Hazards — The air concentration of mercury vapor corresponding to
the equilibrium vapor pressure at room temperature (20°C) is approximately
20 mg per m3, or 200 times the safe concentration of 0.1 mg per m3 for con-
tinuous exposure (8 hr per day, 5 days per week); safe concentrations for
shorter periods have not been proposed. Inhalation of mercury vapor of con-
centrations greater than 0.1 mg per m3 over a long period of time can cause
chronic poisoning. The initial symptoms of poisoning may include gingivitis,
digestive disturbance, fine tremor of the extremities, irritability, excessive
emotional response, and exaggerated salivation. These symptons may increase
in severity and may result in permanent disability. Exposure to concentra-
tions far greater than the maximum allowable concentration for short periods
of time can cause acute illness. The exact nature, concentration, and dura-
tion of exposure determine the type and severity of symptoms. Although inha-
lation of mercury vapor is by far the greatest avenue of entry to the body,
ingestion and absorption through the skin are also possible.
Use — Whenever possible, use of mercury for test purposes should be avoided.
Personnel working in an area where mercury is used should be made aware of its
hazards .
Detection — Direct reading units for determining the concentration of mer-
cury vapor are available from the following sources:
Mine Safety Appliances Company
211 N. Braddock Ave.
Pittsburgh, Pennsylvania 15208
93
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Union Industrial Equipment Corporation (UNTCO)
150 Cove St.
Fall River, Massachusetts 02720
Acton Associates
1180 Raymond Blvd.
Newark, New Jersey 07102
Beckman Instruments, Inc.
2500 Harbor Blvd.
Fullerton, California 9263^
Handling—The precautions listed below should be observed when handling
mercury:
a. Mercury should not be heated without elaborate control because of the
rapid increase of vapor pressure with increase in temperature.
b. Eating and smoking should not be permitted in areas where mercury is
handled. Hands should be thoroughly washed after handling mercury.
c. A change of clothes should be available if clothing is contaminated.
d. Respiratory protection should be available where there is a possi-
bility of contamination.
e. All laboratories handling mercury should have a precise plan to be
followed in decontamination after a mercury spill. Some general pro-
posals are:
(l) Maximum general exhaust ventilation and local exhaust should be
effected. Windows should be opened.
(2) A vacuum flask or a vacuum cleaner designed for removal of mercury
should be put into service immediately to recover the mercury.
(3) The area should be decontaminated by treating with flowers of
sulfur or other decontaminant.
(k) Effectiveness of decontamination should be verified with a mercury
vapor detector-
Facilities—In facilities where mercury is handled the measures listed
below should be taken.
a. Floors of areas should be free of cracks and the intersection of the
wall and floor should be fitted with a cove.
b. Recirculation of air in room should be discouraged because of the
possibility of buildup of mercury vapor.
c. Mercury manometers should be provided with traps to insure that there
will be no spillage of mercury into a process line or into room.
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d. Precision equipment should be removed from areas where contamination
with mercury is possible.
Transportation and Storage—When transporting and storing mercury the fol-
lowing precautions should be taken.
a. Mercury containers should be placed in a tray when transported within
the laboratory; metal or continuous type (nonwelded) plastic con-
tainers are preferable to glass ones.
b. Mercury containers should be stored in pans that will contain any
spillage.
PERMEABILITY
Permeability is a measure of the rate of flow of water or fluid through a
material. The physical structure and the arrangement of constituent particles
greatly affect the size and continuity of the spaces (voids or pores) between
particles. These voids control the rate of flow. Such material properties
and behavior as drainage, consolidation, seepage, and stability are highly
dependent on the material permeability. Due to the large variation in physi-
cal structure and composition of pulp and paper-mill sludges, the permeability
of sludges will show a wide variation.
The flow of water through a sludge medium is assumed to follow Darcy's law:
q = kiA
where q = rate of discharge through a sludge of cross-sectional area, A
k = coefficient of permeability
i = hydraulic gradient, the loss of hydraulic head per unit distance of
flow
The coefficient of permeability, k (often termed "permeability"), is defined
as the rate of discharge of water at a temperature of 20°C under conditions of
laminar flow through a unit cross-sectional area of a sludge medium under a
unit hydraulic gradient. The coefficient of permeability has the dimensions
of a velocity and is usually expressed in centimetres per second.
Permeability computed on the basis of Darcy's law is limited to the condi-
tions of laminar flow and complete saturation (amount of water) of the voids.
In turbulent flow, the flow is no longer proportional to the first power of
the hydraulic gradient. Under conditions of incomplete saturation, the flow
is in a transient state and is time-dependent. Permeability decreases as the
degree of consolidation increases, because of a reduction of the volume of
voids.
There are several standard procedures for investigating permeability and
95
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these can be found in Reference 36. Permeability determination procedures
recommended for the purposes of this manual will be presented in the section
on Consolidation Tests belov. An investigation of various factors affecting
the permeability of sludges can be found in Reference 2.
ASH AND ORGANIC CONTENTS
Pulp and paper-mill sludge has organic material that is generally com-
bustible and mineral materials that are incombustible and ash-forming.
A procedure (35) for determining ash content is to fire an ovendried
sludge sample in a muffle furnace at a temperature of 600°C. The specimen
should be fired until it has obviously been reduced to an ash (probably at
least 3 hr). An alternate procedure (25) is to fire the specimen in a
crucible over a bunsen burner, in which case extreme care must be taken that
the ash is not carried away by the hot air currents. For either method, the
ash content AC is determined from the equation
/ . N weight of ash or residue n,._,
A percent = —j° ^TT ~—^~^ x 10°
c dry weight of sludge
Percent organic content Oc can be considered (25) equal to
0 = 100 - A
c c
This is an approximate method and can be in error from 5 to 15 percent, be-
cause more than organic matter can be burned off the specimen. The ash and
organic contents for a sludge can be added to the previously suggested data
sheets for the same sludge.
PHYSICAL DESCRIPTION OF FIBRES
For future use, analysis, and understanding of the behavior of pulp and
paper-mill sludges, some type of physical description of the fibrous content
should be made. The description can be added or attached to the previously
suggested data sheets. The following is a list of suggested descriptors that
may be modified or added to:
a. Type of fibres.
b. Percent different average fibre lengths and diameters. Fibres could
be separated by a set of different size strainers or sieves.
c. Average fibre length-to-diameter ratios (aspect ratios).
d. Average tensile strengths of fibres.
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CONSOLIDATION TEST
The procedures presented in the following paragraphs are from Reference 36;
however, Reference 3^ is also applicable. Consolidation is the process of
gradual transfer of an applied load from the pore water to the sludge struc-
ture as pore water is squeezed out of the voids. The amount of water that
escapes depends on the size of the load and compressibility of the sludge.
The rate at which it escapes depends on the coefficient of permeability,
thickness, and compressibility of the sludge. The rate and amount of con-
solidation with load are usually determined in the laboratory by the one-
dimensional consolidation test. In this test, a laterally confined sludge is
subjected to successively increased vertical pressure, allowing free drainage
from the top and bottom surfaces.
Apparatus
The apparatus should consist of the following:
a. A consolidometer with a rigid base, a consolidation ring, porous
stones, a rigid loading plate, and a support for a dial indicator
(Figure B-12). The various metal parts of the consolidometer will be
of the same noncorrosive material. All-plastic or combination plastic
and metal consolidometers may also be used to reduce electrochemical
effects. The consolidometer will be of the fixed-ring type and will
have a rigid base with a recess for supporting the bottom porous stone
and for seating and attaching the consolidation ring. The upper sur-
face of the recess will be grooved to permit drainage. The base will
also have (l) an inundation ring to permit submergence of the specimen
in water to prevent evaporation of water from the specimen during the
test, and (2) suitable connections and a standpipe for making perme-
ability tests.
b. Consolidation ring will completely and rigidly confine and support the
specimen laterally. The inside diameter of the ring should not be
less than 2-3A in. and preferably not less than k in.; use of larger
rings for specimens of larger diameter, particularly with the fixed-
ring consolidometer, will reduce the percentage of applied load
carried by side friction and consequently will provide more accurate
results. Normally, the ratio of the height of ring to inside diameter
of ring should be between lA and 1/6. The consolidation ring may be
lined with a material such as Teflon to reduce the friction between
the ring and the specimen. A stainless steel ring is preferable for
specimens containing abrasive particles.
c. Porous stones more pervious than the specimen of sludge should be used
to permit effective drainage. For routine testing, stones of high
porosity should be used. The diameter of the porous stones will be
such as to prevent the squeezing out of sludge through the clearance
spaces between the ring and stone and to permit free compression of
the specimen without binding; to minimize the possibility of binding,
the sides of the upper porous stone of the fixed-ring consolidometer
should be slightly tapered away from the specimen. A clearance of
97
-------
about 0.010 to 0.015 in. around the stone generally may be adequate;
however, if very soft sludges are tested, a smaller clearance may be
desirable or retainer rings may be used as shown in Figure B-12. De-
tails of a typical retainer ring are shown in Figure B-13. The porous
stones should be cleaned after every test, preferably in an ultrasonic
cleaner or by boiling and flushing.
d. Loading devices of various types may be used to apply load to the
specimen. The most commonly used is the beam-and-weight mechanism.
The loading device should be capable of transmitting axial load to the
specimen quickly and gently. Also, the equipment should be capable of
maintaining the load constant for at least 2U hr. The equipment
should be calibrated to insure that the loads indicated are those ac-
tually applied to the sludge specimen.
e. Dial indicator. A dial indicator reading counterclockwise, with a
range of 0.50 in. and graduated to 0.0001 in., is recommended.
f. Other items needed are:
(l) Glass or plastic tubing for standpipe.
(2) Timing device, a watch or clock with second hand.
(3) Centigrade thermometer, range 0 to 50°C, accurate to 0.1°C.
(M Deaired distilled water-
(5) Filter papers, glass plates, and a circular metal plate, approxi-
mately 0.05 in. thick and slightly less in diameter than the in-
side of the consolidation ring.
(6) Apparatus necessary to determine water and solid contents and
specific gravity.
(?) Manometer board or suitable scales for measuring levels in
standpipe.
Preparation of Specimens
Specimens will be prepared in a humid room to prevent evaporation of
sludge moisture. With the consolidation ring set on a glass plate, a test
specimen can be prepared by hand-placing sludge material into the ring. The
sludge should be placed in uniform layers about lA in. thick. Care should be
taken to insure that no space in the ring is left unfilled and that the speci-
men is made as uniform as possible. Carefully true the surface flush with the
specimen ring. Force the metal plate into the top of the specimen until it is
flush with the top of the ring, thereby providing a recess for the top porous
stone. Remove the metal plate.
Procedure
The procedure shall consist of the following steps:
a. Record all identifying information for the specimen, such as project
-------
number and other pertinent data, on the data sheets (Plates B-7 and
P-8 are suggested forms); note any difficulties encountered in prepa-
ration of the specimen. Measure and record height and cross-sectional
area of the specimen. Record weight of specimen ring and glass plate.
After specimen is prepared, record the veight of the specimen plus
tare (ring and glass plate). It is recommended that water content and
specific gravity tests be made on representative material for every
consolidation test specimen. Record the wet weight of the material
used for the water content determination on the data sheet.
b. Fill the grooves in the base of the consolidometer with water. Fit
the porous stone (previously saturated with water) into the base of
the consolidometer. Add sufficient water so that the water level is
at the top of the porous stone. Place a moist filter paper (Whatman
No. 1 or equal) over the porous stone. (Be very careful to avoid
entrapping any air during the assembly operations.) Place the ring
with the specimen therein on top of the porous stone. Secure the ring
to the base by means of clamps and screws.
c. Place a moist filter paper on top of the specimen, and then place the
previously saturated top porous stone and the loading plate in
positiqn.
d. Place the consolidometer containing the specimen in the loading device.
e. Attach the dial indicator support to the consolidometer, and adjust it
so that the stem of the dial indicator is centered with respect to the
specimen. Adjust the dial indicator to permit the approximate maximum
travel of the gage but still allow measurement of any swelling.
f. Adjust the loading device until it just makes contact with the speci-
men. The seating load should not exceed about 0.01 ton/ft2 (l ton/ft
« 1 kg/cm2).
g. Read the dial indicator, and record the reading on a data sheet
(Plate B-9 is a suggested form). This is the initial reading of the
dial indicator.
h. With the specimen assembled in the loading device, apply a load of
0.25 ton/ft2 to the specimen and immediately inundate the specimen by
filling the volume within the inundation ring or the chamber surround-
ing the specimen with water. Place a thermometer in the water, and
record the temperature at 2-hr intervals. To obtain reliable time-
consolidation curves the temperature should not vary more than +2°C
during the test. A load of 0.25 ton/ft2 should be enough to prevent
swelling, but if swelling occurs apply additional load increments
until swelling ceases. Were the specimen permitted to swell, the re-
sulting void ratio-pressure curve would have a more gradual curvature.
i.
Continue consolidation of the specimen by applying the next load in-
crement. The following loading schedule is considered satisfactory
for routine tests: 0.25, 0.5, 1.0, 2.0, U.O, 8.0, and l6.0 tons/ft2,
99
-------
the total load being doubled by each load increment.
j. Observe and record on the data sheet (Plate B-9) the deformation as
determined from dial indicator readings after various elapsed times.
Readings at 0, 1/4, 1/2, 1, 2-1/4, 4, 6-1/4, 9, 12-1/4, l6, 20-1/4, 25,
36, and 49 min, and 1, 2, 4, 8, and 24 hr for each load increment are
usually satisfactory. A timing device should be located near the con-
solidometer to insure accurately timed measurements. Allow each load
increment to remain on the specimen for a minimum of 24 hr. It is de-
sirable that the duration of all load increments be the same. During
the course of the test, plot the dial reading versus time data for
each load increment on a semilogarithmic plot as shown in Plate B-10.
Plot the dial reading on an arithmetic scale (ordinate) and the corre-
sponding elapsed time on a logarithmic scale (abscissa) as shown in
Figure B-l4. The curve shown in Figure B-l4 can be converted into a
time-consolidation curve using the theory of consolidation. The
100 percent consolidation or the completion of the primary consolida-
tion is arbitrarily defined as the intersection of the tangent to the
curve at the point of inflection, with the tangent to the straight-
line portion representing the secondary time effect. The construction
necessary for determination of the coordinates representing 100 per-
cent consolidation and other degrees of consolidation is shown in Fig-
ure B-l4. In addition to the curve above, plot the dial reading
versus time-data for each load increment on a square root of time plot
as shown in Plate B-ll. Plot the dial reading on the arithmetic scale
and the corresponding elapsed time on the square-root scale as shown
in Figure B-15. The 90 percent primary consolidation is defined as
the point on the data curve cut by a line coinciding at zero time with
a straight line through the early portion of the data plot and having
an inverse slope 1.15 times the straight line slope. After first
drawing a straight line through the data, a second line is drawn
having all abscissas 1.15 times as large as corresponding values on
the first line. The construction necessary for determining 90 percent
primary consolidation is shown in Figure B-15. Calculate the 100 per-
cent primary compression value and time (lOO percent compression
= 1.1111 x 90 percent compression). Use the 100 percent compression
value and time to establish the 100 percent point in Figure B-l4.
k. Record on a data sheet (Plate B-12 is a suggested form) the dial read-
ing for each load increment corresponding to a selected time (usually
24 hr) at which primary consolidation has been completed for all
increments.
1. After the specimen has consolidated under the maximum load, remove the
load in decrements, taking three-quarters of the load off successively
for each of the first two decrements and as considered desirable
thereafter. Take readings of the dial indicator as each decrement is
removed to determine the rebound of the specimen. Observe, record,
and plot the dial readings versus time; loads should not be removed
until the dial readings are relatively constant with time or until the
dial reading versus logarithm of time curve indicates completion of
rebound. The final load at the end of the rebound cycle should be
100
-------
0.1 ton per sq ft or less, and this load should be maintained for
24 hr in order to reduce to a tolerable amount the error in the final
water content determination caused by swelling.
m. When the dial readings indicate no further significant rebound, remove
the dial indicator and disassemble the apparatus. Carefully blot any
excess water from the ring and surface of the specimen, eject the
specimen into a dish of known weight, and weigh the dish and wet
specimen; then oven-dry the wet specimen to constant weight for water
content determination. Record information on Plate B-J.
n. At the end of the consolidation phase under each load increment, a
falling-head permeability test should be conducted. Identifying in-
formation for the specimen is entered on the data sheet (Plate B-8 is
a suggested form). A permeability test apparatus setup is also shown
in Figure B-12. The net head on the specimen may be increased by use
of air pressure; however, the pressure on the specimen void water
should not exceed 25 to 30 percent of the vertical pressure under
which the specimen has consolidated.
o. Determine (as shown in Figure B-l6) and record the height of capillary
rise, hc , for the standpipe.
p. Determine and record the area of the standpipe.
q. Measure and record the initial height L , the cross-sectional area of
the specimen A , and the diameter of the specimen D .
r. Determine and record the height of tailwater h^ (shown in Fig-
ure B-12).
s. Record the initial dial reading D0 (same as in step g).
t. For each load increment conduct two permeability tests. If the two
tests give very different permeability values, conduct tests until the
permeability value is consistent.
u. For each load increment record the load and the dial reading D]_ at
the end of compression.
v. Raise the head of deaired distilled water in the standpipe above the
overflow level of the consolidometer. The difference in head should
not result in an excessively high hydraulic gradient during the test.
w. Begin the test by opening valve A. Start the timer. As the water
flows through the specimen, measure and record the initial height of
water in the standpipe h-j_ , in centimeters, at initial time to , and
the final height of water h2 , in centimeters, at final time tf .
x. Observe and record the temperature of the water in the consolidometer.
101
-------
Computations
Consolidation Tests—
a. From the recorded data compute and record on the data sheet, Plate B-7,
the initial and final water contents. Compute also the height of
solids, void ratio before and after test, initial and final degree of
saturation, and dry density "before test using the following equations.
Equations in brackets are based on units of measurements shown in
Plate B-7.
Height of solids H =
S JT.
H - H
c
Void ratio before tests e = ———-
o H
Hf - Hs
Void ratio after test e = —
I n
w
s
Av r*1 v -\/
x (j x Y
S W
W
s
.A. ^ LJ x |
s
x 2.5^ in-
H
Initial degree of saturation, percent S =
wo
o H - H
100
Final degree of saturation, percent S =
'wf
x 100
W
g
Dry density before test Y, = ^ r
d n x A
W x 62.
s
H x A x
Ib per cu ft
where W = weight of dry sludge, g
S
2
A = area of specimen, cm
G = specific gravity of solids
3
Y = unit weight of water, g per cm
H = height of specimen, in.
H = height of specimen at end of test = H - AH , in., where
AH is the net change in height of specimen
W
H = original height of water =
wo A x
wo
w
W
wo
A x i x 2.54
where W = weight of water in specimen before test, g
in.
102
-------
w w
H = final height of water = = ; _ ,_< in.
wf & A x y A x l x 2.54
v
where W = weight of water in specimen after test, g
wi
The purpose of computing the degree of saturation at the "beginning and
end of the test is to o~btain a check on the accuracy of the data
observed and recorded. An appreciable variation from 100 percent in
the computed degree of saturation at the beginning of the test for
specimens that are known to be completely saturated may indicate the
presence of gas or air in the specimen, or an error in the data or
computations.
From data sheet (Plate B-9) or from dial reading-time plots
(Plates B-10 and B-ll), obtain the final dial reading for each load
increment that corresponds to the selected time interval (usually
2k hr), and record these values on the data sheet (Plate B-12). The
height of voids Hv corresponding to any given load is equal to the
initial height of voids (H - Hs) minus the change in height (AH). The
change in height of the specimen is equal to the accumulative change
of the dial readings. Compute the void ratios of the specimen corre-
sponding to different load increments. The void ratio is numerically
equal to the height of the voids divided by the height of solids. Com-
pute and record in Plate B-12, for each increment of pressure, the co-
efficient of consolidation C as follows:
v
0.8U8 ^
C =
^90 /
AH + AH
TJ — TJ -. - - £_
HI - H - 2
where H = average height of the specimen for the load increment
t = time in seconds for 90 percent primary consolidation from
the square root of the time plot for the load increment
AH = change in height for the previous load increment
AH = change in height for the load increment being considered
Compute and record in Plate B-12, for each load increment of pressure,
the coefficient of secondary consolidation Ca (see Figure B-lU), as
follows:
AH AH
IT IT AHs
C = H H s
a log of one cycle 1 H
103
-------
where AH = decrease in specimen height over the above log cycle
H = initial height of specimen at beginning of test for each
load increment
Permeability Tests—
Compute and record in Plate B-8, for each load increment of pressure, the
coefficient of permeability ^-20 > as ^ °H°'W'S:
/ h - Ah'
k20 = t~ (10S10 h2 - Ah j RT
where C = constant = (2.303 x a)/A
2
a = area of standpipe, cm
2
A = area of specimen, cm
L = height of specimen at end of load increment, cm
t = elapsed time of permeability test, sec
h = initial height of water in standpipe, cm
hp = final height of water in standpipe, cm
Ah = corrected tailwater = h, + h , cm
t c
h = height of tailwater, cm
"0
h = capillary rise, cm
R = correction factor for viscosity of water at 20°C obtained from
Table B-2
Presentation of Results
The results of the consolidation tests will be shown on the report forms,
Plates B-10, B-ll, and B-13. The data will be shown graphically in terms of
time-consolidation curves in the form shown as Plates B-10 and B-ll and in
terms of void ratio-pressure and void ratio-permeability curves in the form
shown as Plate B-13. To obtain the void ratio-pressure curve, the void ratio
e is plotted on the arithmetic scale (ordinate) and the corresponding pres-
sure p , in tons per square foot, on the logarithmic scale (abscissa) as
shown in Figure B-1T. The compression index GC will be determined and shown
on the report form (Plate B-13).
The slope of the straight-line portion of the pressure-void ratio curve on
a semilogarithmic diagram is known as the compression index C . The com-
pression index is defined by the equation
-------
e - e
C -
c log1Q p2 -
where p-j_ and p2 are selected pressures from the straight-line portion of
the curve, and e-^ and e2 are the corresponding void ratios. The compres-
sion index is a measure of the compressibility of a sludge. An example of the
computation of Cc is shown in Figure B-17. For simplification, p2 is
often chosen to be 10 times p , in which case the denominator becomes unity.
If permeability tests are performed in conjunction with the consolidation
test, the coefficient of permeability for each load increment will also be
plotted in the form shown as Plate B-13.
Possible Errors
Consolidation Tests—Following are possible errors that would cause inac-
curate determinations of consolidation and permeability characteristics:
a. Specimen not completely filling ring. The volume of the specimen must
be exactly that of the consolidation ring, otherwise there will not be
complete lateral confinement.
b. Galvanic action in consolidometer. To prevent changes in the consoli-
dation characteristics of the specimen due to galvanic currents, all
metal parts of the consolidometer should be of the same noncorrosive
material; it is preferable that all such parts be made of plastic.
c. Permeability of porous stones too low. The measured rate of consoli-
dation can be markedly affected by the permeability of the porous
stones. The stones should be cleaned after every test to remove em-
bedded sludge particles.
d. Friction between specimen and consolidation ring. Soil tests have
shown that over 20 percent of the load applied to a specimen can be
lost by side friction in a fixed-ring consolidometer. The effect of
side friction can be reduced by (l) using a larger diameter specimen,
(2) using a thinner specimen, and (3) lining the consolidation ring
with Teflon.
e. Inappropriate load increment factor. Depending on the purpose of the
test, a load increment factor of 2.0 (that is, of doubling the total
load by each load increment) may not be satisfactory.
f. Unsatisfactory height (or thickness) of specimen. The height of the
specimen will determine how clearly can be detected the break in the
time-consolidation curve that represents completion of primary con-
solidation. Depending on the character of the sludge, if the specimen
is too thin, the time to 100 percent consolidation may be too rapid,
while if too thick, the break in the curve may be obscured by second-
ary compression. Also, when a load increment factor smaller than 2.0
is used, the thickness of the specimen may have to be increased to
105
-------
cause enough deformation during primary consolidation to define the
"break in the curve.
Permeability Tests—Following are possible errors that would cause inac-
curate determinations of the coefficient of permeability:
a. Stratification or nonuniform compaction of the sludge. If the speci-
men is compacted in layers, any accumulation of fines at the surface
of the layers will reduce the measured coefficient of permeability.
b. Incomplete initial saturation of specimen.
c. Excessive hydraulic gradient. Darcy's law is applicable only to con-
ditions of laminar flow.
d. Air dissolved in water. No other source of error is as troublesome as
the accumulation of air in the specimen from the flowing water. As
water enters the specimen, small quantities of air dissolved in the
water will tend to collect as fine bubbles at the sludge-water inter-
face and reduce the permeability at this interface with increasing
time. The method for detecting and avoiding this problem is consis-
tency of the permeability values.
e. Leakage along side of specimen in consolidometer-
VANE SHEAR TEST
In order to obtain a measure of the undrained sludge shear strength
existing in the field for slope analysis and design, in situ vane shear tests
should be conducted. The vane shear test should be run at every 2 ft of depth
from the top of the sludge to the bottom. Three locations (one-third points)
along each eventual slope should be investigated. The locations should be
about at a distance equal to the landfill height plus 5 ft back from the bot-
tom point at the interface between the sludge and dike. The following equip-
ment and procedures are from Reference hi. Equipment setup for the vane
shear test is shown in Figure B-l8.
Torque Assembly
Requirements for the torque assembly include a gear reduction device ca-
pable of producing constant angular rotation of 1 to 6 deg/min, a calibrated
proving ring with a dial gage* for force measurement, a means of measuring an-
gular rotation in degrees, and thrust bearings to support vane at ground sur-
face. Bearings will be of the type arranged to minimize friction while pre-
venting lateral movement of the vane. The gear reduction and proving ring
device will be calibrated to measure applied torque with an error of less than
5 percent.
Procedure
The following steps describe the procedure for the vane shear test.
106
-------
Advancing Borehole—
Using rotary or wash boring methods, advance "borehole with or without cas-
ing to a point no closer than 18 in. above intended test elevation, maintain-
ing as close to vertical alignment as practical. Use the following cleanout
procedure and maintain hole full of drilling fluid prior to and during test.
With or Without Casing—Cleaning of borehole with or without casing should
not be done through open-end drill rod or sampling spoon.
Jetting—Downward or sideward jetting is not permitted when cleaning below
casing. Use any jet auger that deflects the flow of water or drilling fluid
upward.
Jet Bits—Cleanout with jet bits that direct the flow downward or sideward
is permitted within the casing, but should not be done within 18 in. of in-
tended top of test elevation.
Sand Pump or Bailer—Do not use sand pump or bailer within 18 in. of in-
tended test elevation.
Viscous Drilling Fluid—Viscous drilling fluid should be used to prevent
excess swell and disturbance in the vicinity of the intended test.
Advancing Vane—
Slowly lower vane to bottom of hole and push or jack the additional 18 in.,
recording force necessary to advance vane.
Recording; Maximum Torque T —
max
Immediately after vane is in position with torque assembly in place, ro-
tate vane at constant speed of 1 deg/min and record maximum torque required.
Obtaining Remolded Strength—
To obtain remolded strength, rotate vane at rate of one revolution in
10 seconds for minimum of 12 revolutions without taking readings. Allow time
delay of 5 minutes and perform the previous again.
Obtaining Friction Resistance—
Obtain friction resistance by proceeding as in steps Advancing Vane and
Recording Maximum Torque, using dummy rod without vane attached. Make one de-
termination at each elevation for vane shear tests.
Identification Samples—
After withdrawing vane from hole, remove and preserve a sample of the
sludge adhering to the vane for test of water content.
Interpretation of Test Data—
Determine undrained shear strength by
6(T - friction resistance)(lUU)
o . max
U 2,
vane irD (3H + D,
107
-------
where T = maximum torque in inch-pound as obtained in step Recording Max-
max . m
imum Torque
H = vane height, in.
D = vane diameter, in.
S = undrained shear strength, psf
vane
Friction resistance is obtained in step Obtaining Friction Resistance above.
Presentation of Data—Plot S versus depth.
vane
108
-------
K. J -•»•
,^^^L___— .1. Mtfl
Figure B-l. Determining the weight
of a sludge specimen submerged in
water.
Figure B-2. Evacuating air from samples
in determination of specific gravity. A,
flask; B, splash trap; C, vacuum line.
-------
o
z
III
s-
Q,
U.
o
s-
I
652
S5
J: I
20'
25
30
TEMPERATURE, DEGREES CENTIGRADE
Figure B-3'.- T!ypic.al eali brat Ion cmarre of wolTunmetric flask.
CONTEIMT-
\>, SO'LBD
1 SESMI6SOUO
j PLASTBC
SBMBLIQUBD ^
SHKINSKAGE
LMWPT
OMPT
Figore B— k. Sltages of cornsistenqy.
110
-------
NOTE ON DIMENSIONS:
GROOVING TOOL
IMPORTANT NOTE FOR
CALIBRATION OF HEIGHT OF FALL:
haight of ctnt«r of thmy contact tpol
(not of lowitt point) above ba*« is
IOmm • gog* height.
Grooving
Tool Gag*
CALIBRATION OF HEIGHT OF FALL
Figure B-5- Liquid limit device.
Ill
-------
-«> _
rO '•
JL.__
2-^0.08—
51
b!?
*
^
Drill 8~5Xe"
Drill and Tap
1/4-20
'/4-20 Allen
Set Screw
p
IB-T
DETAIL E
(SteeO
8.3"'0.33"
Rod=6~'A
DETAIL D
(Brass)
Drill and Tap
10-24
25^1"
Steel Pin-)-,
3~l/e"Dia
Drill ond
Tap 4-40-
3-/e"
I3«i/fe|
KV
2
in
»
7
01
75°
V-
''>*cr
DETAIL F
(Steel)
2
00
Knurled-
6v'/4"
6-32
Screw
i/ ii O
l3v'/2 *
^
DETAIL G
(Brat*)
Mil
Knurled
"\
IO
CSI
^i
^
DETAIL H
(Braes)
DETAIL
(Bran)
DETAIL K
(B r a i s)
0
I
INCHES
NOTE ON DIMENSIONS:
First dimension given Is in millimeters.
~meons some tolerance is permitted.
• means dimension must be precise.
Figure B-6. Details of liquid limit device.
112
-------
Figure B-T- Grooving liquid limit
specimen.
Figure B-8. Closed liquid limit
groove.
Figure B-9. Plastic limit
d e termi nat ion.
Figure B-10. Crumbling of threads at
plastic limit.
113
-------
1/8" DIAM
1/16" x 3" x 3" GLASS
15/16" 15/16"
RADIUS = 0.54"
15/16'
BRASS PINS SECURED
WITH 3ALSAM
1/32" DIAM
n
1/32'
1/8" [j U T
7/16"
WET SLUDGE'
PAT :
SHRINKAGE
DISH
'DRY SLUDGE
PAT ;
GLASS PLATE
EVAPORATING DISH.
TOP OF GLASS DISH
GROUND SURFACE
MERCURY DISPLACED
BY SLUDGE PAT
DRY SLUDGE PAT
Figure B-ll. Apparatus for determining the volume of dry sludge pat of
shrinkage limit test.
llU
-------
STANDPIPE AREA =(
NOTE: VALVE BETWEEN DEAIRED DISTILLED WATER
JUG AND CONSOLIDATION A P P A R A T U S SH OU L D
BE CLOSED DURING THE PERMEABILITY TEST.
h HEIGHT OF CAPILLARY RISE
a
a INSIDE AREA OF STANDPIPE
A CROSS-SECTIONAL AREA OF SPECIMEN
L LEN GTH O F SPECIMEN
h - H EIGHT OF WATER IN STANDPIPE
° AT TIME , tQ
h, HEIGHT OF WATER IN STANDPIPE
AT TIME, tf
h( = HEIGHT OF TAILWATER
Figure B-12. Typical consolidometer (fixed-ring type) with
falling-head device for permeability test.
115
-------
J_"_
8
-H h-
JL"
16
INSIDE DIAMETER OF CONSOLIDATION RING - 0.005
SECTION A-A
Figure B-13. Typical retainer ring
116
-------
H
-
-------
•t
I
o
13
Z
Q
<
Ld
tr
SLOPE 2 = J./5x SLOPE 7
SLOPE 7
d9Q = 90% COMPRESSION
= TIME FOR 90% COMPRESSION
/TIME
Figure B-15- Square root of time-consolidation curve.
118
-------
= HEIGHT OF
CAPILLARY RISE
STANDPIPE AREA = CL
FL EX/ BL E
TUBE
DE AIRED
DISTILLED WATER
Figure B-l6. Determination of height of capillary rise.
119
-------
0.6
O.I
0.5 1.0 5.0
PRESSURE p, TONS/SQ FT
Figure B-1T- Void ratio-pressure curve.
10
20
120
-------
SEE
TORQUE ASSEMBLY
D = 2 MIN.
CASING FOR SUPPORT
OF TORQUE ASSEMBLY.
USE MINIMUM
EMBEDMENT OF
3- 1/2'.
ROD TO CASING GUIDE
BEARINGS. USE ONE
IN UPPER 3- 1/2' AND
ONE EVERY 30' IN
CASED HOLES
VANE ROD
1 A
It
1
A '
t °
J ™
I
i
Figure B-l8. Vane shear test equipment.
121
-------
TABLE B-l. RELATIVE DENSITY OF WATER AND CORRECTION FACTOR K FOR VARIOUS TEMPERATURES
Temperature
°C
18.0
18.1
18.2
18.3
18.U
18.5
18.6
18.7
18.8
18.9
19.0
19.1
19.2
19.3
19. U
19-5
19.6
19.7
19.8
19.9
20.0
20.1
20.2
20.3
20.U
20.5
20.6
20.7
20.8
20.9
21.0
21.1
21.2
21.3
21.1*
21.5
21.6
21.7
21.8
21.9
22.0
22.1
22.2
22.3
22.1*
22.5
22.6
22.7
22.8
22.9
Relative
Density*
0.99862
0.99860
0.99858
0.99856
0.99851*
0.99852
0.99850
0.9981*9
0.9981*7
0.9981*5
0.9981*3
0.9981*1
0.99839
0.99837
0.99835
0.99833
0.99831
0.99829
0.99827
0.99825
0.99823
0.99821
0.99819
0-99817
0.99815
0.99813
0.99810
0.99808
0.99806
0.99801*
0.99802
0.99800
0.99798
0.99796
0.99793
0.99791
0.99789
0.99787
0.99785
0.99783
0.99780
0.99778
0.99775
0.99773
0.99770
0.99768
0.99765
0.99763
0.99761
0.99758
Correction
Factor, Kt
l.OOOU
i.oooi*
l.OOOU
1.0003
1.0003
1.0003
1.0003
1.0003
1.0002
1.0002
1.0002
1.0002
1.0002
1.0001
1.0001
1.0001
1.0001
1.0001
1.0000
1.0000
1.0000
1.0000
1.0000
0.9999
0.9999
0.9999
0.9999
0.9998
0.9998
0.9998
0.9998
0.9998
0.9998
0.9997
0.9997
0.9997
0.9997
0.9996
0.9996
0.9996
0.9996
0.9996
0.9995
0.9995
0.9995
0.9995
0.9991*
0.9991*
0.9991*
0.9991*
Temperature
°C
23.0
23.1
23.2
23.3
23.1*
23.5
23.6
23.7
23.8
23.9
2l*.0
21*. 1
2l*.2
21*. 3
2l*.l*
2l*.5
21*. 6
21*. 7
2H. 8
21*. 9
25.0
25.1
25.2
25.3
25.1*
25.5
25.6
25.7
25.8
25.9
26.0
26.1
26.2
26.3
26.1*
26.5
26.6
26.7
26.8
26.9
27.0
27.1
27.2
27.3
27.1*
27.5
27.6
27-7
27.8
27.9
Relative
Density
0.99756
0.99751*
0.99751
0.997149
0.9971*6
0.9971*1*
0.9971*2
0.99739
0.99737
0.99731*
0.99732
0.99729
0.99727
0.9972!*
0.99722
0.99720
0.99717
0-99711*
0.99712
0.99709
0.99707
0.9970!*
0.99702
0.99699
0.99697
0.99691*
0.99691
0.99689
0.99687
0.9968!*
0.99681
0.99678
0.99676
0.99673
0.99670
0.99668
0.99665
0.99663
0.99660
0.99657
0.996^)!*
0.99651
0.9961*8
0.996^6
0.9961*3
0.9961*0
0.99637
0.9963!*
0.99632
0.99629
Correction
Factor, K
0.9993
0.9993
0.9993
0.9993
0.9992
0.9992
0.9992
0.9992
0.9991
0.9991
0.9991
0.9991
0.9990
0.9990
0.9990
0.9990
0.9989
0.9989
0.9989
0.9989
0.9988
0.9988
0.9988
0.9988
0.9987
0.9987
0.9987
0.9987
0.9986
0.9986
0.9986
0.9986
0.9985
0.9985
0.9985
0.998!*
0.998!*
0.998!*
0.998!*
0.9983
0.9983
0.9983
0.9982
0.9982
0.9982
0.9982
0.9981
0.9981
0.9981
0.9981
Temperature
°C
28.0
28.1
28.2
28.3
28.1*
28.5
28.6
28.7
28.8
28.9
29.0
29.1
29.2
29.3
29.!*
29-5
29.6
29.7
29.8
29-9
30.0
30.1
30.2
30.3
30.1*
30.5
30.6
30.7
30.8
30.9
31.0
31.1
31.2
31.3
31.1*
31.5
31.6
31.7
31.8
31.9
32.0
32.1
32.2
32.3
32.1*
32.5
32.6
32.7
32.8
32.9
Relative
Density
0.99626
0.99623
0.99620
0.99617
0.996l!*
0.99611
0.99608
0.99606
0.99603
0.99600
0.99597
0.99591*
0.99591
0.99588
0.99585
0.99582
0.99579
0.99576
0.99573
0.99570
0.99567
0.99561*
0.99561
0.99558
0.99555
0.99552
0.995!*9
0.995!*6
0.9951*3
0.9951*0
0.99537
0.99533
0.99530
0.99527
0.99521*
0.99521
0.99518
0.99515
0.99512
0.99509
0.99505
0.99502
0.99!*99
0.991*96
0.991*93
0.991*90
0.99!*86
0.99!*83
0.99!*8o
0.991*77
Correction
Factor, K
0.9980
0.9980
0.9980
0.9980
0.9979
0.9979
0.9979
0.9978
0.9978
0.9978
0.9977
0.9977
0.9977
0.9976
0.9976
0.9976
0.9976
0.9975
0.9975
0.9975
0.9971*
0.997!*
0.9971*
0.9973
0.9973
0.9973
0.9973
0.9972
0.9972
0.9972
0.9971
0.9971
0.9971
0.9970
0.9970
0.9970
0.9969
0.9969
0.9969
0.9969
0.9968
0.9968
0.9968
0.9967
0.9967
0.9967
0.9966
0.9966
0.9966
0.9965
*Relative density of water based on density of water at 1*°C equal to unity. Data obtained from Smith-
sonian Tables, compiled by various authors.
tCorrection factor K is found by dividing the relative density of water at the test temperature by the
relative density of water at 20°C.
122
-------
TABLE B-2. CORRECTION FACTOR
RT
FOR VISCOSITY OF WATER AT VARIOUS TEMPERATURES
Temperature
°C
0.0
1.0
2.0
3.0
>+.0
5.0
6.0
7.0
8.0
9.0
10.0
11.0
12.0
13.0
I**. 0
15.0
16.0
17.0
18.0
19.0
20.0
21.0
22.0
23.0
2k. 0.
25.0
26.0
27.0
28.0
29.0
30.0
31.0
32.0
33.0
3l+. 0
35.0
36.0
37.0
38.0
39.0
1+0.0
1+1.0
1+2.0
1+3.0
I+l+.O
1+5.0
1+6.0
1+7.0
1+8.0
1+9.0
0
1.783
1.723
l.66k
l.6ll
1.560
1.511
1.1*65
1.1+21
1.379
• 1.339
1.301
1.265
1.230
1.197
1.165
1.135
1.106
1.077
1.051
1.025
1.000
0.976
0.953
0.931
0.910
0.889
0.869
0.850
0.832
0.8ll+
0.797
0.780
0.76U
0.7^9
0.733
0.719
0.705
0.691
0.678
0.665
0.653
0.61+1
0.629
0.618
0.607
0.596
0.585
0.575
0.565
0.556
1
1.777
1.717
1.659
1.606
1.555
1.507
1.1+61
1.1+17
1.375
1.336
1.298
1.262
1.227
1.191+
1.162
1.132
1.103
1.075
l.Ql+8
1.022
0.998
0.97*+
0.951
0.929
0.908
0.887
0.867
0.81+8
0.830
0.812
0.795
0.778
0.763
0.71+7
0.732
0.718
0.70U
0.690
0.677
0.661;
0.652
0.639
0.628
0.6l6
0.606
0.595
0.581+
0.57!+
0.561+
0.555
2
1.771
1.711
1.651;
1.601
1.550
1.502
1.1+57
1.1+13
1.371
1-332
1.29U
1.258
1.223
1.190
1.159
1.129
1.100
1.072
l.Ql+5
1.020
0.995
0.972
0.9U9
0.927
0.906
0.885
0.866
0.81+7
0.828
0.810
0.793
0.777
0.761
0.71+6
0.731
0.716
0.702
0.689
0.675
0.663
0.650
0.638
0.627
0.615
o.6oi+
0.59>+
0.583
0.573
0.561+
0.551+
3
1.765
1.705
1.6U8
1.596
1.51+5
1.1+98
1.1+52
1.1+09
1.367
1.328
1.290
1.255
1.220
1.187
1.156
1.126
1.097
1.069
1.0^+3
1.017
0.993
0.969
0.91+7
0.925
0.901+
0.883
0.86U
0.81+5
0.826
0.809
0.792
0.775
0.759
O.lhk
0.729
0.715
0.701
0.687
0.671+
0.661
0.61+9
0.637
0.626
0.6lU
0.603
0.593
0.582
0.572
0.563
0.553
Tenths
1+
1.759
1.699
1.61+3
1.590
1.51+0
1.1+93
1.1+1+8
1.1+01+
1.363
1.321+
1.287
1.251
1.217
1.181+
1.153
1.123
1.091+
1.067
l.Ol+O
1.015
0.990
0.967
0.91+1+
0.923
0.901
0.881
0.862
0.81+3
0.825
0.807
0.790
0.77^
0.758
0.71+3
0.728
0.713
0.699
0.686
0.673
0.660
0.61+8
0.636
0.621+
0.613
0.602
0.592
0.581
0.571
0.562
0.552
of °C
5
1.753
1.69!+
1.638
1.585
1.535
1.1+88
1.1+1+3
1.1*00
1.359
1.320
1.283
1.21+8
1.213
1.181
1.150
1.120
1.091
1.061+
1.038
1.012
0.988
0.965
0.91+2
0.920
0.899
0.879
0.860
0.81+1
0.823
0.805
0.788
0.772
0.756
0.7!+!
0.726
0.712
0.698
0.685
0.672
0.659
0.61+7
0.635
0.623
0.612
0.601
0.591
0.580
0.570
0.561
0.551
6
1.7^7
1.688
1.632
1.580
1.531
1.1+81+
1.1+39
1.396
1.355
1.317
1.279
1.21+1+
1.210
1.178
1.1 Vf
1.117
1.089
I.o6l
1.035
1.010
0.986
0.962
0.9^0
0.918
0.897
0.877
0.858
0.839
0.821
0.801+
0.787
0.770
0.755
0.739
0.725
0.711
0.697
0.683
0.670
0.658
0.61+6
0.63!+
0.622
0.611
0.600
0.590
0.579
0.569
0.560
0.550
7
1.71+1
1.682
1.627
1.575
1.526
1.1+79
1.1+35
1.392
1.351
1.313
1.276
1.21+1
1.207
1.175
l.ll+U
1.111+
1.086
1.059
1.033
1.007
0.983
0.960
0.938
0.916
0.895
0.875
0.856
0.837
0.819
0.802
0.785
0.769
0.753
0.738
0.723
0.709
0.695
0.682
0.669
0.656
0.61+1+
0.632
0.621
0.610
0.599
0.588
0.578
0.568
0.559
0.5>+9
8
1.735
1.676
1.622
1.570
1.521
1.1+75
1.1+30
1.388
1.31+7
1.309
1.272
1.237
1.203
1.171
l.ll+l
1.111
1.083
1.056
1.030
1.005
0.981
0.958
0.936
0.911+
0.893
0.873
0.85!+
0.836
0.8l8
0.800
0.783
0.767
0.752
0.736
0.722
0.708
0.691+
o.68l
0.668
0.655
0.61+3
0.631
0.620
0.609
0.598
0.587
0.577
0.567
0.588
0.5>+8
9
1.729
1.670
1.616
1.565
1.516
1.1+70
1.1+26
1.383
1.31+3
1.305
1.269
1.23!*
1.200
1.168
1.138
1.108
1.080
1.053
1.027
1.002
0.979
0.955
0.933
0.912
0.891
0.871
0.852
0.83U
0.816
0.798
0.782
0.766
0.750
0.735
0.720
0.706
0.693
0.679
0.666
0.65U
0.61+2
0.630
0.619
0.6o8
0.597
0.586
0.576
0.566
0.557
o.s^a
Note: Computed from Table 170, Smithsonian Physical Tables, 8th edition.
Correction factor RT is found by dividing the viscosity of water at the test
temperature by the viscosity of vater at 20°C.
123
-------
WATER CONTENT — GENERAL
DATE
PRO IF[~T
SAMPLE OR SPECIMEN NO.
TARE NO.
WEIGHT IN GRAMS
TARE PLUS WET SLUDGE
TARE PLUS DRY SLUDGE
WATER
ww
TARE
DRY SOLIDS
WATER CONTENT
SOLIDS CONTENT
*S
w
S
SAMPLE OR SPECIMEN NO.
TARE NO.
WEIGHT IN GRAMS
TARE PLUS WET SLUDGE
TARE PLUS DRY SLUDGE
WATER
Ww
TARE
DRY SOLIDS
WATER CONTENT
SOLIDS CONTENT
«s
w
S
SAMPLE OR SPECIMEN NO.
TARE NO.
WEIGHT IN GRAMS
TARE PLUS WET SLUDGE
TARE PLUS DRY SLUDGE
WATER
TARE
DRY SOLIDS
WATER CONTENT
SOLIDS CONTENT
W7.
S%
RE*.
ww
*s
w
S
7o
7,
%
7.
%
%
%
%
1.
%
7,
%
7.
7.
1
%
%
7.
(TARE PLUS WET SLUDGEl - (TARE PLUS DRY SLUDGE) Ww
(TARE PLUS DRY SLUDGE) — (TARE) Ws
Ws 100
(TARE PLUS WET SLUDGE) — (TARE) ' w
Too '
«ARKS
°>,
%
7o
7.
%
1,
- X 100. OR
7U
7o
%
%
7,
7,
"•
%
7.
%
70
7,
f\00 \
\ s /
COMPUTED BY CHECKED BY
PLATE B-l
-------
UNIT WEIGHTS
(VOLUMETRIC METHOD)
PROJECT
DATF
WATER CONTENT
SAMPLE OR SPECIMEN NO.
TARE
in
WEIGHT IN GRAN
NO.
TARE PLUS WET SLUDGE
TARE PLUS DRY SLUDGE
WATER
Ww
TARE
DRY SLUDGE
WATER CONTENT
SOLI DS CONTENT
ws
w
S
7o
<",
-"7
-
WEIGHT-VOLUME RELATIONS
SAMPLE OR SPECIMEN NO.
VOLUMETRIC CONTAINER NO.
CENTI-
METERS
N GRAMS
WEIGHT 1
VOLUME
IN CC
:t
5s
VOLU
t 1 F N
MAY
SPE
REMA
COMP
HEIGHT OF CONTAINER
INSIDE DIAMETER OF CONTAINER
H
D
WET SLUDGE AND TARE
TARE
WET SLUDGE
DRY SLUDGEt
WET SLUDGE (VOLUME OF CYLINDER)
WET UNIT WT - (W/V) 62.4
DRY UNIT WT = (Ws / V) 62. 4
7TD2H
VIE O F CYLIN DER V VOLUME
4
OT MEASURED ON ENTIRE SPECIMEN. DR
W
W
Ws
V
ym
yA
: OF WATER. vw
r WEIGHT
i
5 1 + 0.01 w
CIFIC GRAVITY OF WATER IN METRIC SYSTEM
RKS
Ww
SPECIFIC GRAVITY OF WATERt
= 1 (APPROX)
UTED BY ruFCKFD BY
PLATE B-2
125
-------
UNIT WEIGHTS
(DISPLACEMENT METHOD)
PROJECT
DATE
WATER CONTENT
SAMPLE OR SPECIMEN NO.
TARE NO.
WEIGHT IN GRAMS
TARE PLUS WET SLUDGE
TARE PLUS DRY SLUDGE
WATER
TARE
DRY SLUDGE
WATER CONTENT
SOLIDS CONTENT
Ww
«s
w
S
%
%
°7
%
%
%
%
%
WEIGHT-VOLUME RELATIONS
SAMPLE OR SPECIMEN NO.
TEST TEMPERATURE OF WATER. T, C
WEIGHT IN GRAMS
VOLUME IN CC
st
52
VOLU
t I F N
\ VOL
REMA
COMP
SLUDGE AND WAX IN AIR
WET SLUDGE
W
WAX
WET SLUDGE AND WAX IN WATER
DRY SLUDGEt
ws
WET SLUDGE AND WAXt
WAX
WET SLUDGE
DRY SLUDGE = WS/GS
WET UNIT WT - (W/V) 62.4
DRY UNIT WT = (WS/V) 62.4
V
vs
ym
?i
WEIGHT OF WAX
SPECIFIC GRAVITY OF WAX
DT MEASURED DIRECTLY. MAY BE COMPUTED AS FOLLO
/WEIGHT OF WET SLUDG
UME OP WET -LUDCC AND «AX -> AN° WAX 'N A'R
W
ws. ws - , +0 01 w
E\_f WEIGHT OF WET SLUDGE\
/ \ AND WAX IN WATER )
DENSITY OF WATER AT TEST TEMPERATURE
RKS
JTED BY CHFCKED BY
PLATE B-3
126
-------
SPECIFIC GRAVITY TESTS
DATE
PROJECT
SPECIFIC GRAVITY OF SOLIDS. Gs
SAMPLE OR SPECIMEN NO.
F LASK NO.
TEMPERATURE OF WATER AND SLUDGE, T. °C
DISH NO.
WEIGHT IN GRAMS
DISH t DRY SLUDGE
DISH
DRY SLUDGE
FLASK » WATER AT T, "C
ws
«bw
ws • wbw
FLASK WATER * IMMERSED SLUDGE
DISPLACED WATER, Ws + Wbw Wbws
CORRECTION FACTOR
(WSKI •=- (Ws + Wbw - Wbws)
w bws
K
GS
REMA RKS
COMPUTED RY CHECKED BY
PLATE B-U
127
-------
LIQUID AND PLASTIC LIMIT TESTS
DATE
PROJ
SAMPIf M"
LIQUID LIMIT
RUN NO
TARE NO.
WEIGHT 1
IN GRAMS
TARE PLUS WET SLUDGE
TARE PLUS DRY SLUDGE
WATER W
TARE
DRY SLUDGE W S
WATER CONTENT W
NUMBER OF BLOWS
1
2
3
5
^
t^
f
4
S 10 20 30 40
NUMBER OF BLOWS
5
6
LL
PL
PI
PLASTIC LIMIT
RUN NO
WEIGHT
IN GRAMS
TARE NO
TARE PLUS WET SLUDGE
TARE PLUS DRY SLUDGE
WATER W w
TARE
DRY SLUDGE S
WATER CONTENT *
PLASTIC LIMIT
1
2
3
4
5
NATURAL
WATER
CONTENT
BFMARKS
CHECKED 8V
PLATE B-5
128
-------
SHRINKAGE LIMIT TEST
PROJECT
DATE
SAMPLE OR SPECIMEN NO.
SHRINKAGE DISH NO.
N GRAMS
H
I
0
UJ
t
VOLUME IN CC
DISH PLUS WET SLUDGE
DISH PLUS DRY SLUDGE
WATER
SHRINKAGE DISH
DRY SLUDGE
DISPLACED MERCURY + EVAPORATING DISH
w
** w
*s
EVAPORATING DISH
DISPLACED MERCURY
SHRINKAGE DISH (WET SLUDGE PAT)
VOLUME OF DRY SLUDGE
V _ Vs
V - Vs
*s
Ww
WATER CONTENT = -^ X 100
ws
SHRINKAGE LIMIT
SHRINKAGE RATIO
Vs =
SL =
\
WEIGHT OF DISPLACED MERCURY
V
vs
w
SL
R
X
%
SPECIFIC GRAVITY OF MERCURY (13.53 g/cc
WATER CONTENT OF WET SLUDGE PAT
^VOLUME OF WET SLUDGE PAT- VOLUME OF OVEN-DRY SLUDGE PAT\
\ WEIGHT OF OVEN-DRY SLUDGE PAT )
WEIGHT OF OVEN-DRY SLUDGE PAT Ws
1«
1.
/V - V5 \
(— X 10°)
VOLUME OF OVEN-DRY SLUDGE PAT Vs
REMARKS
COMPUTED BY
r.MECKED BY
PLATE B-6
129
-------
CONSOLIDATION TEST
(Specimen Deta)
Date .
Project.
Sample No.
Classification
Before Test
After Test
Specimen
Extra material
Specimen
Tare No.
Ring and plates
Tare plus wet sludge
Tare plus dry sludge
Water
W
wf
Tare
Dry soil
8f
Water content w
Consolldometer No.
Area of specimen, A, sq cm
Weight of ring, g
Height of specimen, H, in.
Weight of plates, g
Sp gr of solids, G8
Height of solids, Hs = A x 0. x y
x 1 x 2.
in.
Original height of water, H = .
WO A X 7
X 1 X 2. 54
in.
Final height of water,
x 1 x 2.5U
in.
Net change in height of specimen at end of test, AH
Height of specimen at end of test, H. = H - AH
H - H r
in.
in.
Void ratio before test, e =
Void ratio after test, ef
Hf -Hs
H
Degree of saturation before test, S = =-
O n •• u
6
H
Degree of saturation after test, S. = = =-
f Hf ' He
Dry density before test, 7
62.4
d H X A
Ib/cu ft
Remarks
Computed by
_Checked by
PLATE B-1
130
-------
FALLING-HEAD PERMEABILITY TEST
PROJECT
WITH CONSOLIDOMETER
j
DATE
SAMPLE OR SPECIMEN NO.
WT IN GRAMS
TARE PLUS DRY SLUDGE
TARE
DRY SOLIDS W$
SPECIFIC GRAVITY Gj
VOL OF SOLIDS. CC = W + G V
AREA
OF STANDPIPE, SO CM •
CAPILLARY RISE. CM h(
HEIGHT OF TAILWATER. CM h.
TEST NO.
LOAD
DIAL
INCREMENT. T/SO FT
READING AT START, IN.
CHANGE IN HT OF SPEC. IN. » D - D.
0 1
HT OF SPEC, CM = L - 2.M AD
VOID
RATIO « (AL - v§) + vt
P
D,
Ao
L
.
INITU
kL TIME
FINAL TIME
ELAPSED TIME. SIC ='(-'„
INITIAL HEIGHT. CM
FINAL HEIGHT, CM
WATER TEMPERATURE. "C
VISCOSITY CORRECTION FACTOR
121
CM/SEC
(1t CORRECTION FACTOR FOR VISCOSITY 0
111 i 0 L ^i ~ Ak r
REMARKS
t.
'l
1
k,
h,
T
R T
k»
AVG
F WAT
LOG
DIAMETER OF SPECIMEN, CM
AREA OF SPECIMEN. SO CM
INITIAL HEIGHT OF SPECIMEN. CM
INITIAL VOL OF SPEC, CC * AL
INITIAL VOID RATIO = (V - Vf) * V,
INITIAL DIAL READING, IN.
CORRECTED TAILWATEH. CM, h, + hc
1
10
-------
CONSOLIDATION TEST
(TIME-CONSOLIDATION DATA!
PROJECT
SAMPLE NC
DATE AND
PRESSURE
3.
TIME
ELAPSED
TIME. MIN
DIAL RDG.
10-4 IN.
TEMP
•c
DATE
CONSOL. NO.
DATE AND
PRESSURE
TIME
ELAPSED
TIME, MIN
DIAL RDG.
10-" IN.
TEMP
•c
CONDUCTED BY
PLATE B-C
132
-------
DEFORMATION IN 10"1 INCHES
0 o
1 0.2 0.5
TIME IN MINUTES
12 5 10 20 50 100 200 500 1000 2000
NOTE: NUMBERS ftESIDE CURVES
ARE PRESSURES IN T/SQ FT.
"" 1 "
r
i
.._
" !
1
+~ ~^
I
i
—
j_
i j '
[
!
|
i
1
J_
\
i
102 0.5 1 2 5 10 20 50 100 200 500 1000 2000
TIME IN MINUTES
PKOJECT
AREA
SAMPLE NO.
DATE
CONSOLIDATION TEST-TIME CURVES
PLATE B-10
133
-------
£
1-3
td
U)
f
2
DC
o
li.
UJ
Q
NOTE: NUMBERS BESIDE CURVES
ARE PRESSURES IN T/SQ FT
10
100
500
1000
2000
Dial reading versus time-data for each load increment
-------
OJ
td
I
CONSOLIDATION TEST
(COMPUTATION OF VOID RATIOS)
DATE
PROJECT
SAMPLE NO. CONSOLIDOMETER NO.
PRESSURE, f
T/SQ FT
DATE
INCREMENT
APPLIED
HEIGHT OF VOIDS. MV = |H - HS) -
H v
VOID RATIO. C =
H ,
CONDUCTED BY
TIME IN MIN
INCREMENT
EFFECTIVE
DIAL READING
10-* IN.
H =
COMPUTED BY
CHANGE IN
HEIGHT, AH
10-4 IN.
HEIGHT OF
VOIDS. Hv
10-* IN.
VOID RATIO, e
COEFFICIENT OF
CONSOLIDATION
Cv, 10~* IN.2/SEC
COEFFICIENT OF
SECONDARY
COMPRESSION
Co, 10-3/MIN
CHECKED BY
-------
0
0)
0
-H
-p
a)
K
T)
T-t
§
0
Coefficient of Permeability, kg0, 10" cm/sec
1 0.2 0.3 OAO-5 1 23^5 10 20 25
1 0.2 0.3 O.UO-5 1 23^5 10 20 25
Pressure, p, T/aq ft
Type of Specimen
Diam in.
Ht in.
Compression Index, Cc
Classification
LL
PL
G
Remarks
Before Test
Water Content, w
Void Ratio, e
Saturation, S
Dry Density, 7^
*
%
lb/ft3
After Test
Wf
ef
Sf
*
*
k2Q at CQ x 10" cm/sec
Project
Area
Sample No.
Date
CONSOLIDATION TEST REPORT
PLATE B-13
136
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/3-76-111
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTm P
DESIGN CONSIDERATIONS FOR PULP AND PAPER-MILL
SLUDGE LANDFILLS
5. REPORT DATE
December 1976 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Richard H.
Ledbetter
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORG "VNIZATION NAME AND ADDRESS
Soils and Pavements Laboratory
U.S. Army Engineer Waterways Experiment Station
P.O. Box 631, Vicksburg, Mississippi 39180
10. PROGRAM ELEMENT NO.
1DB064 (SOS#3 Task 05)
11. CONTRACT/GRANT NO.
EPA-IAG-D5-F657
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory - Cin., OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final Jan. '75-Jan. '76
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
Robert E. Landreth
513/684-7871
- Project Officer
16. ABSTRACT
This report presents procedures for the engineering design and control of
pulp and paper-mill sludge disposal landfills. Engineering design will allow
more efficient use, thereby contributing to economic and environmental benefits.
To form the basis for engineering design of sludge material, the methodologies
and theories of soil mechanics were applied. The methodologies should be ap-
plicable to most compositions of sludge materials. Some sludge materials may
have peculiarities associated with testing, field workability, and behavior.
However, from accumulated experiences of applying the procedures of this
manual, the manual can be adjusted and expanded.
This report is specifically written for pulp and paper-mill personnel of
technical background but with little or no exposure to the soil mechanics dis-
cipline. The procedures are such that these individuals can rationally approach
a landfill operation to attain efficiency and optimization. This report does
not present a rigorous treatment or analysis of sludge material, but it does
give the above-mentioned individuals the procedures for determining good approx-
imations of sludge behavior. Individuals interested in more rigorous and theo-
retical analysis of sludge behavior should consult the list of references.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
waste disposal
sludge disposal
soils
paper mi 1 Is
soil mechanics
solid waste management
sludge landfill
landfill
13B
S. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
151
20. SECURITY CLASS (This page)
:LASSIFTFH
22. PRICE
EPA Form 2220-1 (9-73)
137
•4U.S. GOVERNMENT PRINTING OFFICE. 1977- 757-056/5467
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