FIRST FINAL DRAFT
GUIDE FOR THE MONITORING
AND ENFORCEMENT OF LAND DISPOSAL
OF SOILD WASTE
January 1976
PRELIMINARY
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ACKNOWLEDGEMENTS.
The monitoring volume of this manual was prepared
for the U. S. Environmental Protection Agency,
Office of Solid Waste -Management Programs, by
Wehran Engineering Corporation, Mlddletown, N, Y.
and Geraghty & Miller, Inc., Port Washington, N. Y,
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PRELIMINARY
27265
TABLE OF CONTENTS
27266
CHAPTER
1. INTRODUCTION
2. EXECUTIVE SUMMARY
(In Progress)
3. FUNDAMENTALS OF LEACHATE
3.1 Introduction
3.2 Origin, Composition and Fate of Leachate
.1 Refuse Zone
.2 Unsaturated Zone
.3 Aquifer Zone
.4 Measurement of Attenuation
3.3 Leachate Quantity
4. MONITORING NETWORKS
4.1 Monitoring Networks
.1 Intergranular Porosity
.2 Fracture Porosity
.3 Solution Porosity
4.2 Leachate Movement in Different Hydrogeologic
Settings
5. MONITORING AND SAMPLING TECHNIQUES
5.1 Monitoring Techniques
.1 Zone of Aeration (Soil Water)
.2 Soil Sample Analysis
.3 Suction Lysimeters
.4 Trench Lysimeters
5.2 Zone of Saturation (Ground Water)
.1 Wells Screened Over a Single Vertical Interval
.2 Piezometers
.3 Well Clusters
.4 Single Well/Multiple Sampling Points
.5 Sampling During Drilling
.6 Pore Water Extraction From Core Samples
5.3 Other
Field Inspection
Surface Water Quality Measurements
Seeps
Vegetation Stress
Measurement of Conductivity and Temperature
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CHAPTER
5.3 (Continued)
Seismac Surveys
Earth Resistivity Survey
Geophysical Well Logging
Landfill Gas Measurements
Aerial Photography
Water Balance Analysis
5.4 Well Technology
Drilling Technology
Well Casing and Screen Materials
Well Security
Water Withdrawal Methods
6. INDICATORS OF LEACHATE
6.1 Introduction
6.2 Background Quality of the Ground Water
.1 Chemical Quality of Natural Ground Water
.2 Other Sources of Ground-Water Contamination
6.3 Chemical, Phusical and Biological Indicators
6.4 Indicator Groups
.1 Specific Conductance Measurements
.2 Key Indicator Analyses Group
.3 Extended Indicator Analyses Group
6.5 Guidelines for Using Indicators
.1 Background Water Quality Monitoring
1.1 New Land Disposal Site
1.2 Existing Land Disposal Site
.2 On-Going Monitoring
6.6 Monitoring Frequency
.1 Characteristics of Ground-Water Flow
.2 Location and Purpose of the Monitoring Well
.3 Climatological Characteristics
.4 Trends in the Monitoring Data
.5 Legal and Institutional Data Needs
.6 Other Considerations
6.7 Cost Considerations
6.8 Data Management
.1 General
.2 Application of Statistics
.3 Indicator Data Profiles
7. SAMPLING, STORAGE & PRESERVATION
7.1 Introduction
7.2 Sample Collection
.1 Sample Collection Techniques
.2 Records
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CHAPTER
7. (Continued) 7.3 Sample Containers
7.4 Preservation of Samples and Sample
Volume Requirements
7.5 Preservation of Samples in the Field
ANALYTICAL METHODS
8.1 Introduction
8.2 Alternate Analytical Methods
.1 Method Comparability
.2 Other Analytical Methods
8.3 Specific Analytical Methods of the Analysis
of Relatively Concentrated Leachate Samples
.1 Introduction
.2 Measurement of Interference Effects
8.4 Analytical Methods
8.5 Brief Description of Specific Analytical
Methods for Leachate Analysis
.1 Physical Parameters
.2 Organic Chemical Parameters
.3 Inorganic Chemical Parameters
.4 Biological Parameters
8.6 Field Testing Versus Testing in the Laboratory
8.7 Automated Methods
8.8 Laboratory Quality Control
8.9 Manpower and Skill Requirements
8.10 Records, Data Handling and Reporting
STEP OUTLINE OF MONITORING PROCEDURES
9.1 Introduction
9.2 Step 1 - Initial Site Inspection
.1 Nature of the Waste
.2 Areal Extent and Thickness of the Landfill
.3 Pretreatment and In-Place Treatment of Refuse
.4 Landfilling Procedures
.5 Rate of Landfilling and Refuse Age
.6 Liners and Covers
.7 Visual Survey of Topography and Geology
.8 Ground-Water Use (Preliminary)
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CHAPTER
9. (Continued)
9.3 Step 2 - Preliminary Investigations
,1 Existing Data
.2 Preliminary Site Investigation
9.4 Step 3 - Definition of the Hydrogeologic Setting
. 1 Surficial Geology
.2 Bedrock Geology
.3 Ground Water
.4 Determine Existing Water Quality
.5 Determination of the Rate of Leachate Generation
9.5 Step 4 - Determine the Polluting Potential of
the Landfill
9.6 Step 5 - Establish the Monitoring Program
.1 Select the Monitoring Sites
.2 Determine Monitoring Objectives
.3 Establish the Monitoring Methods and Procedures
Necessary to Accomplish Objectives
.4 Establish Management Program
9.7 Examples of Landfill Contamination Problems
.1 Scenario 1 - A Landfill Contamination Study
.2 Scenario 2 - A Ground-Water Contamination Study
APPENDIX
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CHAPTER 1
INTRODUCTION
The land serves as the ultimate repository for over 90% of our Nation's
solid waste. Incineration, shredding, and resource recovery processes
reduce the amount of solid waste but produce residues requiring disposal.
The main environmental problem of concern at a land disposal site is leachate
generation and its resultant potential pollution threat to ground and surface
waters. Leachate is liquid which has percolated through solid waste and has
extracted dissolved and suspended materials from it. Whenever water comes
in direct contact with solid waste it becomes contaminated. In humid areas
of the country (where precipitation exceeds evapotranspiration) there will
be a net infiltration of water into a land disposal site resulting in leachate
generation. In arid and semi-arid areas, precipitation by itself will not
be sufficient to result in significant amounts of leachate; however, problems
can occur from deficiencies in the site, or its operation and design. The
pollution potential of leachate along with the growing concern for the limited
assimilative abilities of our Nation's air, water and land resources all point
to the importance of monitoring
This manual is primarily concerned with the monitoring of land disposal sites
disposing of municipal solid waste (MSW). Emphasis is placed on the monitoring
of ground-water quality, with the monitoring well being the key tool in per-
forming this function. The manual is concerned with both existing and new
land disposal sites, the former being the more common case.
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This manual is primarily addressed Co the bureau chiefs of tin- solid
waste regulatory agencies, although its contents can be readily used by
operators, researchers and consulting engineers in the field. It is
offered as a guide to be used and tailored by the bureau chief, at his
discretion, in implementing and directing an effective monitoring and
enforcement program in his state and is intended to provide broad general
direction and guidance to persons without prior training or experience.
It will also bring into one volume information valuable as a reference
source for those persons actively engaged in landfill monitoring. It
should also prove helpful to the operators and managers of land disposal
sites who now will find a need for familiarization and understanding of the
fundamental principles involved in ground-water pollution and monitoring.
This manual has a companion volume which addresses the enforcement aspects
of monitoring. It is intended that, used together, the two volumes will
assist the regulatory programs to "bridge the gap" between the monitoring
performed and the enforcement data needs.
Generally, this manual includes fundamentals and guidelines to assist the
user in,
. establishing the need for monitoring.
. assigning priorities for sites to be monitored.
. implementing and directing a cost-effective, on-going
program responsive to the enforcement data needs.
The information, as presented, is offered as guidelines and preferred methods
only and site specificity is recognized throughout the manual.
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PRELIMINARY
CHAPTER 3
FUNDAMENTALS OF LEACHATE
3.1 INTRODUCTION
As discussed in Chapter 2, it is important to understand and assess the
potential for leachate contamination at a land disposal site, in order to
properly design, implement and interpret a monitoring program and its data.
Here we are referring to leachate production, its quality, quantity and its
fate in the hydrogeologic environ. A clear understanding of each of these
concepts, their underlying theories, causes and results, should be pre-
requisite to the design of a monitoring program. Placement of monitoring
wells, sampling frequencies, sampling analyses, data interpretation and
environmental impact assessment will all benefit from a clear understanding
of the above-mentioned concepts.
This chapter presents an overview of the fundamentals of leachate and is
keyed into a more detailed presentation in the Appendix of the manual. It
is intended that the material presented will be useful to the user of the
manual in making an environmental assessment of potential leachate contamin-
ation for a particular land disposal site, and utilizing this to properly
design and operate a monitoring program and interpret the resultant data.
Further, the within information may be useful to regulatory officials in the
preparation of background and reference information for enforcement cases.
In approaching the monitoring of a land disposal site, one faces the following
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considerations:
what kind of contamination are we monitoring for?
how much contamination in terms of concentration and
quantity can be expected?
where, how fast, and how far will the contamination
travel?
how do we best monitor for the contamination?
All of these questions require a clear understanding of leachate production
and its fate in the landfill and surrounding environment.
3.2 ORIGIN, COMPOSITION AND FATE OF LEACHATE
In understanding the quality of leachate, and contaminants and the concen-
trations that may be encountered by monitoring, one must consider its quality
as the leachate emanates from the compacted solid waste and its quality as
the leachate travels in the subsurface environ. The former would be the
quality of pure leachate, while the latter deals with the quality of "leachate
enriched ground water."
Precipitation percolates into materials deposited in a solid waste landfill
and by lixiviation (dissolving of soluble components) produces a solution
called leachate. The landfill leachate under conditions where infiltration
is greater than runoff and evapotranspiration combined, moves downward
through refuse, and through underlying soil and sediment until it reaches
an impermeable layer or ground water. In its journey, leachate traverses
three zones of geochemical activity with certain characteristics which are
shared and others which are unique to each. The ensuing discussion will
describe some of the characteristics in each of the zones and ways in which
they interact with the constituents of leachate. The general principles
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will be presented here, and a more complete discussion appears in the
Appendix.
3.2.1 REFUSE ZONE
Solid waste deposited in municipal landfills is a heterogeneous mixture of
organic and inorganic materials and living organisms. Upon deposition, and
frequently before, microbial activity begins the degradative process on
organic matter. The microbial decomposition of organic matter is encouraged
by moisture and warm temperatures.
Microbial activity soon uses up the supply of oxygen and causes the refuse
beyond the zone of rapid air diffusion to go anaerobic. Anaerobic conditions
cause the end products of decomposition to be somewhat different from carbon
dioxide and water which are the products of complete oxidation. Notable
among the products of anaerobic decomposition is methane gas. Other organic
anaerobic decomposition products such as alcohols, aldehydes, and thiols
tend to be more odoriferous than their aerobic counterparts. Of particular
importance with regard to leachate, are the anaerobic forms of sulfur,
nitrogen, iron, and manganese.
The percolate flows downward through the refuse which is in progressively
advanced stages of decomposition, and it passes through layers of buried
cover material. Percolate shows a net gain in dissolved constituents as it
progresses downward, but may lose some individual ions from cation exchange
or other reactions encountered en route.
Nitrogen present in refuse organic matter is released in soluble form with
microbial decomposition. In organic substances, nitrogen is in a chemically
reduced state. With aerobic decomposition, the nitrogen is oxidized to
nitrate ion. Under anaerobic conditions, nitorgen is released as ammonium
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ion. Anaerobic conditions are predominant in landfills. Thus most
nitrogen in leachate is present as ammonium. The relatively small amount
of nitrate produced coupled with its probable denitrification explains the
typically low nitrate concentration in leachate.
Organic decomposition releases carbon dioxide in large amounts under aerobic
conditions, and in smaller amounts under anaerobic conditions. The enrich-
ment of the interstitial gas in refuse by carbon dioxide results in produc-
tion of bicarbonate ion. Bicarbonate is frequently a major anion in leachate.
Because of the reversibility of the reaction producing bicarbonate, it acts
as a pll buffer.
Heavy metals in landfills are primarily in their metallic state and are not
soluble. The exception is with deposition of soluble heavy metal salts
either as solids or in solution. These may come from certain industrial
activities such as electroplating or metal pickling. Most heavy metals
occur in solution as cations, but a few are usually present as anions.
Anionic heavy metals include vanadium, chromium, and molybdenum.
Phosphorus is released to percolating water by decomposition of organic
matter. As discussed below, soils have a high capacity for phosphate
attenuation, where as the refuse material does not. Phosphate can be and
frequently is produced in substantial amounts in leachate. Were leachate
to enter ground water directly, it would almost certainly contribute more
phosphate than percolate which has passed through soil and an unsaturated
zone.
Water quality parameters which do not measure individual chemical species
include biochemical oxygen demand (BOD), chemical oxygen demand (COD),
total organic carbon (TOC), color, conductance, and turbidity. The refuse
zone provides little, if any, attenuation of these parameters, instead it
usually contributes to them.
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Feral collform and fecal streptococci have been observed in leachate, and
poliovirus was reported In leachate from a simulated landfill. The recent
trend to use of disposable diapers has increased the source of enteric
bacteria and viruses in solid waste. Sewage sludge and septage are also
frequently disposed of in municipal landfills.
Movement of bacteria and viruses within the landfill and through the unsat-
urated zone is dependent upon the porosity of refuse and underlying geologic
formations. Refuse may offer many paths through which water can travel
relatively unimpeded. If coarse sand and gravel or fractured rock under-
lie the refuse, percolating water may carry microorganisms with little or no
attentuation except for natural die off. These conditions judging from loca-
tions which have been studied, are the exception rather than the rule.
Much data on pure leachate quality has been reported in the literature
which is worthy of note. The U. S. Environmental Protection Agency has pre-
pared Table 3.1, which illustrates some of the chemical and biological
characteristics found in pure leachate and compares fresh leachate to a
typical domestic waste water. The quality of leachate depends upon many
variables which are specific to each land disposal site. Therefore, a
recent EPA report emphasizes the cautious interpretation of reported leachate
data:
"The compositions of leachates reported in the literature
are. quite diverse The breadth of reported data are
also typical for individual studies 17 over a long period
of time. The many factors that contribute to the spread
of data are time since deposition of the solid waste; the
moisture regimen, such as total volume, distribution, in-
tensity, and duration; solid waste characteristics; tem-
perature; and sampling and analytical methods. Other
factors such as landfill geometry and interaction of
leachate with its environment prior to sample collection
also contribute to the spread of data. Most of these
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TABLED
CHARACTERISTICS OF LEACHATE AND DOMESTIC WASTE WATERS
Constituent
Chloride (Cl)
Iron (Pel
Manganese (Hn)
Zinc (Zn)
Magnesium (Hg)
Calcium (Ca)
Potassium (K)
Sodium (Ha]
Phosphate (P)
Copper (Cu)
Lead (Pb)
Cadmium (Cd)
Sulfate
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factors are rarely defined in the literature, making
interpretation and comparison with other studies
difficult, if not rather arbitrary."
In this same report, the EPA has prepared a comprehensive summary of quality
data for both pure leachate and leachate enriched ground water as has been
observed and reported by many researchers. The table along with some
narrative discussion of the data has been duplicated and included in the
Appendix of this manual.
.The significance of microbiological organisms in solid waste has been addressed
by EPA and worthy of note for selecting monitoring analyses:
"There is a dearth of information concerning the microbiology
of solid waste stabilization as it occurs in a land disposal
site. The organisms responsible for stabilization are ubiqui-
tous in nature and are present in the solid waste as well as
in the soil. Therefore, there is an ever-present "seed" of
organisms, and microbial stabilization is inevitable. The
few studies available •*» 4,5, 6,7 confirm this. However,
from the viewpoint of environmental contamination, the lack
of specifity with regard to types and numbers of stabilizing
bacteria and even pathogenic bacteria and viruses, is very
disturbing and in need of additional attention and/or research.
Peterson has isolated type 3 poliovirus and ECHO 2 from muni-
cipal solid waste. Other investigations have determined
that one gram of residential solid waste may contain one
million or more fecal coliform and fecal streptococci 10,11.
Soiled diapers were found to comprise 0.2 to 2.5% by wet
weight of the total waste stream 12 Gaby H has shown
comparable density of fecal coliform and fecal streptococci
(Figure 1). The preliminary findings indicate there is great
public health significance associated with any soild waste
management process. Additional work is required to clarify
these results and determine the bacteriological efficacy of
solid waste management processes".
3.2.2 UNSATURATED ZONE
As used herein, the unsaturated zone is defined as the area in soil or
sediments between the bottom of the landfill deposits and the water table.
The distance can vary between zero (refuse contacting ground water) to
several hundred feet. The zone is below what is usually considered "topsoil"
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Mote: 1. Average of 6 to 8 Determinations
2. Adapted from W. L. Gaby, U.S. EPA Research Contract
68-03-0128, 1972.
\
I
8
3. W/QL Total Coliform
A. ] 1 Fecal Collforn
5. &XX1 Fecal Streptococci
10C
10'
10
10"
10
10-
10
SOLID WASTE
SEWAGE SLUDGE
SOLID WASTE -
SLUDGE MIXTURE
Figure 1. INDICATOR ORGANISMS FOUND IN WASTE STREAMS.
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or the weathered, organic-matter-rich upper horizons of most soils. At most
landfill sites, topsoil has been removed, and sometimes much subsoil also,
prior to deposition of refuse. The porous materials comprising the subsoil
are likely to be low in organic matter, have a sparse microbial population,
and may vary in permeability over a wide range. For purposes of discussion,
we will consider the unsaturated zone to be 20 to 200 feet thick. This
range allows percolating water an opportunity to react chemically with its
environment before reaching ground water. Percolating water has four options
in passing through the unsaturated zone. It can move virtually unchanged,
can show a net gain of solute, show a net loss of solute, or keep the same
total ionic concentration with a net exchange of ions. Since few soils or
sediments are chemically inert, changes in transported solute are to be
expected.
Chemical activity in the unsaturated zone is primarily located at the surfaces
of clay minerals and hydrous oxide coatings. Limited microbial activity may
take place either from the indigenous population or that transported from
refuse.
Cations will be removed from solution until either the cation exchange
capacity is reached, or the limit of displacement reactions is reached.
The limit of cation exchange capacity (CEC) can range from nearly zero
to probably not more than 60 milliequivalents per 100 grams of soil. Sol-
ution concentrations, pH, and percolation rate affect the reactions quan-
titatively. It should be noted that absorption is not a permanent fixation.
Cations may be described with changes in solution composition, pH, or
oxidation-reduction (redox) potential.
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Divalent and trivalent cations include most of the heavy metals. These
are held more strongly than sodium, potassium, or ammonium on the cation
exchange complex. Di- and trivalent cations will displace monovalent
cations which are adsorbed.
Heavy metals are prone to sorption on hydrous oxide coatings in the soil.
The hydrous oxides are frequently cited as so limiting metal solubility that
agricultural deficiencies of copper, zinc, and cobalt occur. Atten-
uation of heavy metals present in leachate is desirable. In locations vir-
tually free of clay minerals, these coatings may be present on sand grains
giving - the sandy formation some ability to attenuate metallic ions.
Absorption is only one mechanism for removing dissolved ions from solution.
Changes in the geochemical environment can also affect solution equilibria.
A transition from reducing conditions in the landfill to oxidizing condi-
tions in the unsaturated zone can reduce the concentration of some redox-
sensitive species in solution and change the chemical form of others. Iron
and manganese will oxidize and precipitate from solution, for example.
If porosity will allow bacterial movement, biochemical reactions involving
leachate constituents can proceed. Sulfide and ammonium can be oxidized to
sulfate and nitrate. Dissolved organic matter measured in terms of BOD and
COD can be reduced through microbial decomposition. Some nutrient elements
in the course of these reactions will be incorporated in bacterial ce£2s
and thereby be removed from solution until the bacterial cells die off.
Conversion of ammonium to nitrate changes nitrogen from a form subject to
attenuation to a form which is not. Sulfide to sulfate oxidation is not ex-
pected to be as significant. Sulfide can form insoluble precipitates with
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many of the heavy metals. For this reason, it may not be present in more
than trace amounts in leachate. Microorganisms may also attack the organic
ligands associated with chelated and complexed metals. Decomposition or
absorption by microorganisms would remove the metals from leachate.
Phosphate reacts with a variety of soil components forming insoluble
products. Calcium and phosphate react in solution to form hydroxyapatite,
the least soluble phosphate compound known. Iron, aluminum, and manganese
can also form virtually insoluble precipitates with phosphate. These reac-
tions lead to a strong attenuation of phosphate when these metal ions are
present in the unsaturated-zone.
Carbonate also reacts with calcium, magnesium, and some heavy metals forming
relatively insoluble compounds. Calcareous deposits in the unsaturated zone
can be valuable in attenuating phosphate and heavy metals from leachate.
Because carbonate neutralizes acids, BOD and COD as expressed in organic acid
concentration may also be reduced. Carbonate induced alkalinity may change
solubilities of heavy metal chelates and lead to a deposition of heavy
metals.
The unsaturated zone is influenced by the percolation of leachate into it
and influences the leachate which percolates into it. Water of low oxida-
tion potential first infiltrating into the unsaturated zone of high oxida-
tion potential will become more oxidized while simultaneously reducing sub-
stances in the unsaturated zone. A continued percolation of reduced water
may convert what had been an oxidized system into a reduced one. Or, the
percolate may become oxidized if that capacity Ln the unsaturated zone is
greater. The degree of influence of reduced leachate on the oxidized unsatur-
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ated zone and vice versa depends upon the reserves of material capable
of oxidizing or reducing in the unsaturated zone and leachate. The greater
the distance leachate travels between refuse and ground water, the better
the chance that the entire path through the unsaturated zone will not be-
come reduced. Raising the oxidation potential of leachate will tend to
attenuate some components in solution at the point of exit of the refuse
zone.
3.2.3 AQUIFER ZONE
Concepts useful for describing surface water pollution are generally not
valid for ground water. Ground-water movement is described by Darcy's Law
which states that velocity is directly proportional to the permeability
of the aquifer and the hydraulic gradient, and inversely proportional to the
porosity. Ground-water flow velocities vary over a wide range with 5 ft/yr
to 5 ft/day being a typical range. Highly permeable outwash glacial
deposits, fractured basalts and granites, and cavernous limestone aquifers
allow very much higher velocities.
The generally slow velocity of ground water allows laminar flow which ex-
hibits different characteristics of mixing than does turbulent flow usually
associated with surface streams. A water of different chemical composition
from ground water which is injected or percolated into ground water tends
to maintain its Integrity, and is not diluted with the entire body of ground
water. Instead, it moves with the ground-water flow as a plume undergoing
minimal mixing.
The plume shape is determined by the physical characteristics of the aquifer.
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Porous media give somewhat different shaped plumes from fractured rock or
cavernous limestone. Chapter 4 illustrates the paths of ground-water
movement In various hydrologic regimes.
Differential attenuation is defined as a reduction in concentration of a
dissolved constituent, with distance along the direction of water flow, which
is disproportional to changes in concentration of other constituents. Differ-
ential attenuation may result from chemical reactions which remove the con-
stituent from solution or from self-destruction. Apparent attenuation
occurs from dilution by mixing with water of lower constituent concentration.
Dilution may take place in ground water in two ways. One is hydrodynamic
dispersion, and the other is molecular diffusion. Microscopic dispersion
describes mixing caused by the tortuous flow of water around individual
grains and through pores of various sizes in a porous aquifer. Microscopic
dispersion describes mixing as water flows in and around heterogeneous
geologic formations. Molecular diffusion operates on a much more restricted
scale. It is the diffusion of solute across a concentration gradient from
stronger to weaker concentration. Diffusion is seldom possible to measure
in the field. There are mathematical formulas which describe dispersion.
By measuring enough physical and chemical parameters at a site, over a suf-
ficient length of time, one can calculate an approximate value for dispersion.
Chemical interactions provide the greatest amount of differential attenuation
in the aquifer zone. Hydrous oxides of iron, aluminum, and manganese, or
clay minerals present in aquifers attenuate cations in the same way that they
do in soils or in the unsaturated zone. Because hydrous oxide and clay
colloids are in constant contact with water in the aquifer, it can be assumed
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that the exchange sites are saturated and essentially in equilibrium with
the ambient ground water. Leachate enriched ground water when contacting
these colloids will initiate cation exchange which results in desorption of
cations which are less strongly held than those replacing them. In this way,
hydrogen, sodium, calcium, and magnesium may be released into the aqueous
phase by exchange with heavy metals and other cations in leachate. High
hardness values associated with leachate plumes may be due in part to this
ion exchange phenomenon.
Chemical precipitation in the aquifer is possible if the natural ground water
composition includes ions which form insoluble compounds with constituents
in leachate. An example would be formation of hydroxyapatite with leachate
phosphate and calcium in ground water. Changes in redox potential, buffering
reactions, or changes in lithology may produce other attenuation reactions.
The third means of attenuation in aquifers is that termed decay. Oxidation
of organic compounds produces carbon dioxide and water, and eliminates
the compounds. Radioactive species undergo radioactive decay to stable
daughter products, but radioactivity should not be significant in leachate
from municipal landfills. Microorganisms carried into the aquifer zone are
deprived of a good nutrient supply and are subjected to a generally cooler
temperature. This results in a lowering of biochemical activity, frequently
to the point of cessation. The inactivation coupled with natural die off
tends to reduce bacterial numbers rather rapidly.
There are two additional complications in the interpretation of ground-water
quality in leachate plumes. One is the variation in leachate concentration
with time, and the other is the discontinuous recharge of leachate which
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occurs in most geographical regions. Chapter 6 presents additional
discussion on data interpretation.
Leachate production begins as soon as deposited refuse is wetted to field
capacity. The lag time depends upon local climatic conditions and rate of
refuse deposition. In an active landfill, older organic matter is stabilizing
while simultaneously new organic matter is beginning to ferment and produce
stronger leachate. The net effect is an increasing leachate concentration
from a given area, or an increasing areal contamination, or both as long
as the landfill is active.
Leachate produced at the initiation of percolation through the landfill is
less concentrated than that produced after several years' refuse accumulation.
This leachate will be found at the distal end of the plume of leachate-con-
taminated ground water. The closer the sampling site to the landfill, the
more concentrated should be the contaminated ground water. An increasingly
concentrated leachate source in addition to the factors of dilution and
attenuation must be considered in interpreting the results of sampling the
plume. An erroneously high value for attenuation or dilution may be given
if the variation in source strength is ignored.
The intermittent recharge occurring from most landfills also complicates
interpretation of leachate-plume configuration. During summer months when
evaporation frequently exceeds rainfall, little or no leachate may be pro-
duced. Ground water, however, moves under the landfill at a relatively
steady rate. Thus, there will be variations in the volume and strength
of'leachate reaching ground water during the course of time. These variations
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will show in the leachate plume as variations in total solute concentration.
A sample taken from the plume at any given time may represent a "high" or
"low" in the intermittent recharge pattern. Oneway to visualize this
phenomenon would be to watch the response of a conductivity probe in a well
screen over time. As leachate-enriched ground water moves past the point,
conductivity will vary with changes in dissolved solids concentration.
The variations may be noticeable only in time spans of weeks to months.
Again, this complicates efforts to calculate values for dispersivity or
dilution because concentrations vary from factors other than aquifer char-
acteristics.
A generalized summary of the susceptibility of leachate constituents is
provided in Table 3.2. The mechanism of attenuation which affects each
constituent is listed for the zones through which leachate may pass. When
data are summarized in this fashion, only the principal mechanisms can be
cited. For example, no attenuation is listed for all of the constituents
in the refuse zone. This is not really true as the previous discussion
points out. However, quantification is impossible, and there is a net output
of most of the constituents. Sulfate, nitrate, and ammonium are given bio-
chemical conversion alternatives. These ions are subject to oxidation and
reduction reactions which may convert or eliminate them. Heavy metals are
also prone to one or more of the attenuation mechanisms, and may not be
universally present in leachate. Biochemical reactions were not listed for
the aquifer zone because biological activity is inhibited. In places,
biological activity may be significant in the aquifer, but the amount and
type cannot be predicted.
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Table 3:2SUSCEPTIBILITY OF LEACHATE CONSTITUENTS TO DIFFERENTIAL
ATTENUATION
Attenuated Constituent
Chloride
Sulfate
Sulfide
Phosphate
Nitrate
Ammonium
Sodium
Potassium
Calcium
Magnesium
Heavy metal onions
(Cr,V.Se,B,As)
Heavy metal cations
(Pb, Cu, Ni , Zn, Cd, Fe, Mn, Hg)
Organic nitrogen
COD
BOD
Volatile Acids
Phenols
MBA$
Refuse Zone
P
0-B
C
0
0-B
0-B
0
0
0
0
0-B
0-A-C
0
0
0
0
0
0
Unsaturated Zone
0
0-B
C-B
A-C
0
A-B
0
A
A
A
0-B
A-C
B
B
B
B
A-B
A-B
Aquifer
0
0
C
A-C
0
A
0
A
A
A
0
A-C
0
0
0
0
0-A
0-A
0 = no attenuation
A = adsorption
B = biochemical degradation on conversion
C = chemical precipitation
-------
!>
Measurement of Attenuation
From the previous discussion, it is evident that attenuation describes two
phenomena associated with the way solute is transported. One is dilution
which results from dispersion and diffusion, and the other is dilution
resulting from chemical or biochemical removal of solute from ground water.
The former type of dilution is referred to as apparent attenuation because
no active chemical processes are operating to reduce the concentration of
dissolved constituents.
In the field, it is important to distinguish between apparent 'and active
attenuation because prediction of future conditions depend upon the extent
of active attenuation. To accomplish this, several samples of leachate-
enriched ground water must be collected along the path of travel of the
leachate plume. Chemical constituents measured in these samples are then
chosen on the basis of their susceptibility to attenuation, and relative
changes in concentration with distance from. the source are noted.
Chloride is the best constituent to measure as a indicator of dilution.
Because it carries a negative charge and does not form precipitates with
the common cations in water, chloride is unaffected by ambient conditions.
Reductions in chloride concentration can then be attributed to the result
of dispersion and diffusion. If ground-water equations were used in an
attempt to calculate dispersion coefficients for leachate-enriched ground
water, chloride concentration data would be first choice for use in the
calculations. Nitrate reacts in virtually the same way, but nitrate is less
frequently present in leachate in comparable concentrations.
3-/7 A,
-------
I?"
r I
Concentrations of other constituents sampled simultaneously with chloride
should represent equal dilution. If they are observed in lower than ex-
pected concentrations , this indicates that active attenuation has ^OHQBI f*-**
^StaB** Conversely, if their concentrations are greater than those calculated
on the basis of chloride, desorption from ion exchange sites or contribu-
tions from other sources may account for the non theoretical results.
An exasiple which is calculated from data obtained in a landfill study is
c \\
presented below. *' The cations calcium, sodium plus potassium, ammonium,
and iron in leachate-enriched ground water are plotted in percentage of
original concentration vs. distance from the landfill (Figure 3- I ). Were
all of the cations diluted equally, they would plot on the same curve.
Reference points for chloride are included to facilitate a comparison of
the theoretical dilution-only curve with the actual cation concentration
curves.
The plume of leachate-enriched ground water represented by Figure 3- | is
produced by a landfill that has been active for 28 years. The leachate
plume can be traced about 10,600 ft. downgradient from the landfill. The
plume extends vertically throughout the thickness of the aquifer (about 80
ft) with the most concentrated contamination near the bottom.
Calcium remains above the chloride curve throughout the length of the plume.
This is in agreement with other reports which have indicated that calcium
is desorbed from clays as a result of cation exchange with leachate
components. In this specific situation, there may also be a contribution
of calcium from septic tank effluent.
Ammonium remains above the chloride curve for about half the length of the
-------
plume. It also may be desorbed and is also a eooponent of septic tank
effluent. The loss of ammonium at more distant points of the plume may be
due in part to generally more aerobic ground-water conditions that allow
nitrification of ammonium.
Sodium and potassium generally plot below the chloride points, and iron
is even more attenuated. Probably the iron is removed largely through
solubility changes resulting from increases in Eh at longer distances
from the landfill.
The geohydrologic environment is characterized by soft, rather acid native
ground water in a highly silicaceous unconsolidated sand and gravel aqui-
fer. Dncontaminated ground water contains iron in concentrations which
frequently exceed the recommended drinking water limit of 0.05 mg/1. No
significant amounts of clay or silt are present in the path of the
leachate plume. Sand grains are coated with iron oxide which probably
exhibits a small amount of cation exchange capacity. Septic tanks in use
in the area and intermittent recharge of leachate as governed by climate
complicate the interpretation of chemical data along purely theoretical
principles.
5-/7C
-------
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MADE IN U. S. A.
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3.3 LEACHATE QUANTITY
In a recent EPA report on leachate ^ , leachate production was phased
into perspective. It stated:
"It becomes quite evident that the main parameter affecting
leachate quality and quantity is purely and simply the quantity
of water flowing through the solid wastes. Generally, the more
water that flows through the solid waste, the more pollutants
will be leached out. Therefore, the proper sanitary landfill
design and operational approach is to eliminate or minimize
percolation through the solid waste. With the smaller amounts
of percolation, the pollutants tend to-be more concentrated,
but the rate at which they are transmitted to the surrounding
environment is not so apt to exceed the capability of the
natural surroundings to accept and attenuate most of them to
some degree."
Therefore, you can see that the volume of leachate generated is influenced in
both the extent of a leachate contamination problem and the relative strength
of the leachate and its concentration in the ground water being
monitored.
The water balance method has been presented as a useful tool in estimating
average leachate quantities at a land disposal site.
"The sanitary landfill site is a part of the classical
hydrologic cycle. The governing criteria for determining
leachate volume are those describing the phenomena occurring
at the cover material surface. A water balance can be written:
WR+ WSR+ WGW+ WIR
where WR = input water from precipitation
WSR = input water from surrounding surface runoff
WGW = input water from groundwater
W,R = input water from irrigation
I = Infiltration
R = Surface Runoff
E = Evapotranspiratio'n
.3-18
-------
Infiltration can be defined:
I =ASs = ASR + L * WD (2)
where ASg » change in moisture storage in soil
£SR = change in moisture storage in solid waste
L = leachate
WD = water contributed by solid waste decomposition
Proper design and operation can eliminate input water from
surrounding surface runoff, groundwater and irrigation. Some
control can be exerted over infiltration, evaporation, surfa'ce
runoff, and moisture storage capacity of soils and solid waste.
The volume of water produced during solid waste decomposition
is generally considered negligible." (4)
Figure 3-1 conceptually depicts the above water balance equations. In addi-
tion, the above-referenced report presents very useful information and data
on the following:
1. the influence of slope, surface condition, and soil
type on the quantity of runoff and the potential for
leachate production.
2* the dependency of infiltration on the storm frequency,
duration, intensity and soil moisture conditions.
3. the influence of vegetation on evapotranspiration and
infiltration
4. the relationship of soil permeabilities to infiltration
rates and volumes.
5. the moisture retention capabilities of various types of
soils as well as compacted municipal solid waste.
All of the above-referenced information provides useful input in assessing
leachate at a land disposal site. For the convenience of the users of this
3-19
-------
manual, sections of the EPA summary report on leachate feu/2.been reproduced
and included in the Appendix.
In another EPA report, the water balance method was applied to three
hypothetical landfills. These examples are worthy of note and have been
included in the Appendix of this manual. They demonstrate how to determine
time of first appearance of leachate as well as subsequent average leachate
generation and volumes.
Caution must be exercised in applying the water balance method to sanitary
landfills. Review of the above-referenced information clearly shows the
extreme sensitivity , of leachate quantity estimates to the many variables
used in the water balance calculations . For example, slight changes in
runoff coefficients, evapotranspixation or moisture retention figures can
result in a significant change in the leachate quantity estimate. In
addition, unless extensive on site measurements- are performed, the many
parameters in the water balance calculations are purely theoretical and
empirical estimates. Therefore, this manual presents the water balance
methods as a useful tool for planning, design and assessment purposes and
the leachate quantity estimates generated should be viewed with this quali-
fication in mind.
3-20
-------
EVAPOTRANSPIRATION (E)
PRECIPITATION (WR)
SURFACE RUNOFF (R)
WSR
WSR
WGW
SANITARY LANDFILL WATER BALANCE
FIGURE 3-1
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4.1 MONITORING NETWORKS
In the context of this - report the ultimate goal of any monitoring
program is to gauge and evaluate ground-water degradation^, if any,
duo te landfill leachate. A presence/absence system is the
minimum acceptable approach - is there leachate in the ground water?
This approach will work in situations where ground-water contamination
did not pre-exist the'monitoring network, in other words, a network
installed prior to any landfilling operation. As is often the case,
landfill operation and subsequent leachate generation have been
going on for some time prior to installation of a monitoring network.
i
If contamination already exists, the monitoring program must provide
the requisite data for the management program. Here,the maximum
feasible approach is- a quantitative evaluation of total contaminant
accumulation in the aquifer, rates of accumulation and attenuation,
and the contaminant dispersion pattern and its controls. To implement
this approach, a time sequence of three-dimensional data on the
contaminant body is required;actd with this information, the proper
management scheme can be devised. For any given sanitary landfill,
the correct monitoring system will be between or even include, these
extremes.
There are two basic approaches to monitoring: active and passive. The
former has a measurable, continuing impact on the ground-water regime,
considerable altering the flow system in which the contaminant source
is located. An active monitoring system is essentially a pumping welj.
which intercepts ground-water from the area that might potentially be
affected by the contaminant (Figure 1 ). Theoretically, any
-------
2.
contaminant entering the zone of intercepted ground-water flow
would eventually be detectable in the monitoring well discharge.
This approach is most suited for point source, "one-shot"
contaminants introduced into the ground water from such sources
as a tank leak or underground nuclear explosion. Unfortunately/
this type of monitoring scheme has several drawbacks preventing
its application to sanitary landfills: 1) the larger the
contaminant source, the greater the number of pumping wells
required to intercept ground-water flow; 2} contaminant
concentrations will be greatly reduced by the volume of water
withdrawn, perhaps below detection limits; 3) disposal of the
pumped water can be a problem, especially if contaminated; 4)
pumping costs over a period of years will be astronomical; and
5) pumping will accelerate the spread of leachate through the
aquifer and eventually the monitoring system will become a
pumped withdrawal system.
Passive.monitoring, on the other hand, is ideally suited to
monitoring landfill leachate. In this type of scheme, wells or
other monitoring devices, strategically located in reference to
ground-water flow directions, are sampled at regular intervals
to determine chemical constituents in the ground water at that
point and time. Flow-pattern disruptions are kept to a minimum.
This is a system that can be used to monitor continuous, long-
term contaminant input from a point source - the situation that
would exist at a landfill. To monitor the area which might be
affected by the contaminant, a "picket fence" of non-pumping wells
is required (Figure 2 ). The main drawback, compared to the
-------
active monitoring approach, is that more than one weTLl is
required. However/ these can be small-diameter wells and
sampling procedure costs can be kept to a minimum and should
cost less in the long run than a major pumping installation.
Background Data Requisite for Monitoring Network Design
Prior to monitoring well construction, some thought should
be given to their placement. A certain amount of information
is required: 1) ground-water flow direction; 2) distribution
of permeable and impermeable materials; 3) type of aquifer
porosity; 4) effect of pumping, present or future, on the flow
These.
system; and 5} background water quality. ThAo data can be
obtained by installing a series of low cost wells, collecting
sediment samples during drilling, and measuring water levels in
the completed wells. Background water quality can be determined
from chemical analysis of water samples from these wells. A
hydrogeologist or engineer familiar with ground water, may be
able to "best guess" the information without actual field work.
However, unless such personnel are involved in designing the
monitoring network, every effort should be made to collect this
information at the site. With this information, monitoring wells
/*'«"»£
can be placed to most effectively intercept any contaminant bulb
spreading from the landfill.
Monitoring Networks for Sanitary Landfills
The minimum acceptable monitoring well network will consist
of one line of three "picket fence" wells downgradient of the
-------
DP A ET
!K f\ ,'i i
landfill and perpendicu^/r to ground-water flow, penetrating
the entire saturated thickness of the aquifer; one well within
the confines of the landfill, screened so that it intercepts
the water table; and a well completed in an area upgradient
from the landfill that will not. be affected by potential
leachate migration. The actual number of wells will be dictated
by the size of the landfill, the hydrogeologic environment, and
budgetary restrictions, but there should be a minimum of five
at each landfill and ideally one "picket fence" well for every
250 feet of landfill frontage perpendicular^flow direction.
Even'if wells are sited according to the background information
described above, there is a high probability of one or more of them
not intercepting the ba-lb of leachate-enriched ground water
because of inhomogen^Lties in aquifer material^ efee. Sequence of
land-filling operations also has a significant effect on the shape
of the leachate plume and the possibility of a well not detecting
leachate, (Figure 3 ). For these reasons, it is better to err on
the side of too many monitoring wells rather than too few.
Once contamination is detected, several "picket fence" lines of
these wells can be constructed and used to gauge downgradient
dispersion and attenuation of the leachate, providing the
i|f^)brmation necessary for predicting the ultimate fate of the plume.
If, however, the contaminant exists in a complicated hydrogeologic
regime, information on its vertical distribution is required to
predict plume behavior and assess its impact. This is the maximum
feasible approach and will be a time consuming and expensive
process, the necessity of'which will depend on t; 3 gravity
-------
5.
of the threatened environmental impact or regulatory requirements.
The single well in the landfill, provided it is properly constructed,
will give an indication of whether or not leachate is reaching
the ground water before it is detected in the downjgradient
"picket-fence" monitor wells. Once detected here, it may be
only a matter of time before leachate-enriched ground water
reaches the downgradient monitor wells. For this reason, it
serves as an important early warning system of potential large-
scale aquifer degradation. Detection of leachate in this well
should trigger a response from the landfill operator, either
implementation of remedial action or wait and see what the
"picket fence" wells show. The actu^al course of action is
is
dependent on federal, state, and local statutes and enforcement
agencies governing ground water contamination or an evaluation
by the operator ( or operator's consultant ) of the consequences
of aquifer degradation.
Some problems can result from relying entirely on this well
or similar wells within the landfill to monitor leachate infiltration
to the ground water. First, it is located within the landfill
proper and does not provide information on the downgradient
extent of leachate-contaminated ground water. Then too, it skims
water from only the surface of the aquifer. If any density
stratification is occuring within the contaminant bulb, the well
would give an unrealistic picture of actual leachate concentration
in the ground water.
-------
c
KAh 8
The major problem, however, is the potential for artificially
elevated leachate concentrations in water samples due to improper
monitor well construction. Since the well is constructed within
the landfill itself, an improperly backfilled annulus can act
as a conduit for downward movement of leachate, introducing it
into the aquifer sooner than might have occurred naturally, if
at all. Proper construction requires some type of impermeable
seal in the annular space between the well casing and the
borehole wall, either bentonite or neat cement grout. Because
grout can shrink and bentonite can dry and crack, their placement
is not a complete guarantee of plugging the annular area and
stopping downward movement of leachate. However, neglecting to
place this seal during monitor well construction is almost certain
to speed and promote ground water contamination.
An upgradient monitor well provides water samples indicative
of background water quality, or in other words, the chemical
character of "naturally" occuring ground water. This well
should be sampled at regular intervals, and the analytical
results used as a baseline for comparison with results from the
landfill and "picket fence" monitor wells. The background well
can also provide information on outside interferences, that is
contaminants in the ground water, naturally occuring or otherwise,
not due to landfill leachate. When a constituents concentration
rises above acceptable levels in all the wells, an outside
if / '
, - ./ -
-------
interference is indicated, A^aturalJLy-occuring) example of this
is^lron-rich ground water and X aVtifiViallV-Induce^ examples -oaRHoe-^^pleiwen±ed~^fc-an.y^j^te^wii;h.^M fy pgobatoillt'y
ftlfntC.
o-f--inte*ceptin^--fehe~€0rvtaininan-t--b**ibn Hydrogeologic conditions
at a particular site will require modification of the basic design
. ')
-------
Table 1'.- Typical Intergronular Porosities
Porosity,
Material per cent
Clay 45-55
Silt 40-50
Medium to coarse mixed sand 35 - 40
Uniform sand 30 - 40
Fi«ve to medium mixed sand 30 - 35
Grivel 30-40
Gravel and sand 20 - 35
Sandstone 10-20
-------
8 •
» '
D
in order for the monitoring network to be effective. These
basic designs are presented Here as guidelines, not standards,
because they are the minimum feasible approach to monitoring
and by nox means will provide all the answers in all of the
various hydrogeologic environments found in the United States.
-------
As a result of past structural deformation, consolidated
sediments and igneous and metamorphic rocks are fractured (broken)
*
to a greater of lesser degree depending on the itensity and/or
frequency of the deformation and the rock type. Water can, fill
v - • -
these fractures, and if they are interconnected and capable of
transmitting water, can form an aquifer. (Figure 4f). The
ability of the aquifer to transmit wa,ter depends on fracture
density and openness: the greater the density of fractures and
the wider they are, the greater their ability to transmit water.
In some cases, the rocks can have, primary and secondary porosity;
primary porosity (intergranular porosity) is produced during
sediment deposition or rock formation and secondary porosity is
caused by fracturing or solution activity after this. Sandstone
is an example of both types of porosity since voids exist between
the sand grains and•sandstone formations are usually fractured.
However, intergranular porosity dominates unless the voids are
filled with cement.
Carbonate rocks are susceptible to solution by water moving through
fractures. With time, these fractures are enlarged into cavities,
creating large open spaces in the rock. Figure 4e). If the
cavities are connected, ground water can move very rapidly through
the aquifer. In fact, carbonate aquifers can have transmissivities
of several million gpd/ft. Solution openings and sinkholes provide
-------
10,
open pathways for leachate to reach the ground water, and
once there, it will move rapidly through the aquifer.
Carbonate rocks can have both intergranular and fracture
porosity/ but where solution cavities exist, ground water will
preferentially move through them.
Type I Network (Intergranular Porosity Aquifers)
Placement, both areal and vertical, of monitor wells in any
hydrogeologic environment should be. done in reference to
ground water flow paths. Rather than discuss this at length
simplified diagrams are used to represent typical flow
patterns in the type of aquifer discussed and the positioning
of monitor wells to effectively intercept any contaminant ^lu^e.
itttib. Figure 5 A and 5 B represent vertical and areal flow
distribution respectively, in a homogeneous, isotropic
sand aquifer. Monitor wells A, B, and C are the background,
landfill, and "picket fence" wells discussed above. To
review, Well A provides baseline water quality data, Well B
is an early warning system showing leachate reaching the
water table immediately beneath the landfill and Well C is
intended to intercept any plume of leachate contamin,ed ground
water.
Areal placement of the upgradient, background monitor well
(Well A) is critical if there is a ground water mound associated
with the landfill. This mound, produced by increased infiltration
due to landfilling, causes a certain amount of upgradient flow
from the landfill (Figure 4B). If Well A is located in this
-------
11.
zone, sampling will produce an anomalous water-quality baseline.
Unfortunately, no rules of thumb can be given as to the
separation between this well and the landfill proper as the
extent of upgradient flow will depend on a variety of factors
including amount of infiltration through the landfill and
aquifer characteristics. The best policy would be to locate
the well at the most distant upgradient point at the landfill
site or on adjacent upgradient property if permission of the
owner can be obtained. Well depth is not critical, assuming
there are no apparent contamination sources in the vicinity,
but better baseline data would be provided if the well were
screened through the saturated thickness of the aquifer.
Well B can be located anywhere in the landfill but
preferentially in the first section to be filled. As discussed
above, great care must be taken during construction. In hydro-
geologic environments where the water table is 5 to 10 feet below
the landfill, monitoring the zone of aeration is probably not
necessary because Well B will detect leachate entering the
ground water. However, where the unsaturated zone is 10 feet
or greater in thickness, some monitoring device is required
to detect to downward percolation of leachate before it reaches
the water table. Pressure-vacuum lysimeters can be used to
trace downward movement of leachate in the vadose zone and can
provide data on the amount of attenuation and the likelihood of
leachate reaching the water table.
The "picket fence" wells (C wells. Figure 5B) should be
-------
12.
DRAFT
immediately downgradient of the landfill in order to intercept
the leachate plume as soon as possible. Once leachate enters
the ground water, it is difficult to control and the sooner it
is detected, the easier it is to evaluate its impact and initiate
nfd
remedial action, if necessary. Well C is shown• screes! through
the entire saturated thickness of the aquifer. This is
recommended because the actual flow path of the leachate plume
is not known unless previously defined by head relations in a
large number of observation wells. The flow .path of leachate-
enriched ground water shown in Figure. 4A is characteristic if
the landfill is located in the aquifer recharge area. If the
landfill were closer to the point of discharge, in this case
the river, the plume would probably be higher in the aquifer.
However, since the physical behavior of contaminant bodies hasn't
been completely described yet, there is almost no way of
knowing where the bs*b of contaminant will be within an aquifer.
Therefore, the monitoring device has to collect water over the
entire saturated thickness of the aquifer and the simplest way
to do this is to screen the entire interval.
This typ^ of construction can cause some problems. The primary
problem is that the well can contribute to the vertical spread
of contaminant by providing a conduit for downward movement of
intercepted ground water. If the aquifer is 50 feet or less in
thickness, this is not a major problem because natural flow
conditions would tend to uniformly distribute the leachate
throughout the aquifer, especially in recharge areas. Thicker
-------
aquifers, 100 to 200 feet of saturated thickness, tend to
have more pronounced shallow and deep flow systems and
there is a chance the Leachate plume would remain the
shallow flow system. A well screened over the entire
saturated thickness provides a movement path from the
shallow to deep flow systems. Of course, this is a gross
simplification and is intended as a guideline only. The
actual flow pattern will depend on the hydrogeologic
environment in which the landfill is located.
This drawback can be overcome by using a well cluster
(see Section ) but the landfill investigator will have
to balance the extra cost against the probability of promoting
the vertical spread of contaminants. Also, well clusters
are not particularly effective in aquifers thicker than one
hundred feet. Because the exact vertical location of the
plume is not known, overlapping or sequential (0 to 10 ft, 10
to 20 ft, and so on) screens are required. For example, in
an aquifer with one hundred feet of saturated sediment, five
wells with twenty feet long screens are required to cover
this interval. As aquifer thickness increases, screen lengths
must increase proportionally and the information on the
vertical distribution of contaminant becomes less and less
?(-•'*£>
precise. If the screens do not overlap, the contaminant ±M±±b •
could pass between the screened intervals and remain undetected.
Another problem is dilution of leachate below analytical
detection limits when a sample is pumped from the well. This
-------
14.
would result in a time lag between first arrival of leachate-
enriched ground water at the monitor well and its first detection
in the sampled water. The magnitude of this lag is hard to
predict but, as the contaminant travels in a defineable -btribb. <->•*£.
with a' small zone of diffusion to uncontaminated water, it
shouldn't take very long for the zone of diffusion to move past
the well and leachate contaminated ground water start to enter.
Then, if detection is still a problem, concentration or extraction
techniques could be used for key leachate tracers to determine
their presence or absence in the sample. Once detected, a more
sophisticated sampling device is required, perhaps well clusters,
sampling during drilling, or others discussed below, since C
wells are only designed to show presence or absence of leachate
and not vertical distribution.
Type II Monitoring Network (Fracture Porosity Aquifers) -
Ground water flow patterns are not as predictable in fractured
rock aquifers as they are in aquifers with intergranular porosity.
Unless there is primary porosity, as in a sandstone aquifer, ground
water flow patterns will be controlled by the fracture pattern.
Again, flow patterns are presented visually in Figures 6A and 6B,
rather than attempting to describe them in great detail. The same
configuration of A, B, and C monitor wells can be used in this
hydrogeologic regime (Figure 6A). However, the wells are not
screened but rather are open hole with the exception of casing-off
-------
15.
"~a iu"
I" I
surficial materials to prevent them from caving into the open
hole.
A major problem in fractured rock terrains is intercepting
the fractures that might contain leachate-contaminated ground
water with a monitor well. As shown in Figure 6C, a well can
fail to intercept any fractures and will be dry, necessitating
another well nearby. Worse yet, a monitor well could intercept
a set of fractures not connected to the landfill and fail
entirely to show leachate entrained in the ground water.
Without intensive and expensive geologic analysis, it is not
possible to predict flow paths other than general ground water
flow direction at the site. Monitor wells cannot be precisely
taken into account in planning a monitoring network and
evaluating the results. To compensate, a high well density is
required, perhaps one monitor well for every 100 feet of landfill
frontage perpendicular to ground water flow.
Another problem is specifying well depth. Fractures are squeezed
shut with depth because of the weight of overlying material. If
shut, fractures are unable to act as conduits for water movement
and the rock can no longer be considered an aquifer. Closed
fractures therefore provide a downward limit on leachate
movement. A general rule of thumb is that fractures tend to
close at depths of 300 feet or greater, and monitor wells probably
should not be drilled deeper unless there is geologic
information to the contrary.
-------
16.
Type III Monitoring Network '(Solution Porosity Aquifer) -
Similar to fractured rock aquifers, ground water flow patterns
are 'going to be controlled by solution openings or fractures in
carbonate rock aquifers. The positioning of the A, B, and C
monitor wells in this type of flow system is shown in Figures
7A and 7B. The monitoring network is the same as that for
fractured rock with the same problems: 1) intercepting the
solution cavities and 2) well completion depth. Again,
increased well density can solve the former but there are no
handy rules of thumb for the latter, as in fractured rocks.
Sinkholes can be 100 feet or more deep and there is no telling
how deep solution cavities will persist. Unless the solution
cavities follow a well known regional fracture system, there is
no way to predict their position prior to placing a monitor well
without geologic analysis. A trial and error approach to
placement is mandated by the hydrogeologic environment and there
is no assurance that the wells will intercept the contaminant baib'
-------
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INTERCEPTION BY PUMPING
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INTERCEPTION BY NONPUMPING VrE
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1,
\
\
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WL
N\
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C
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ft
xW. V®
V
to o..
-------
4.2 LEACHATE MOVEMENT IN DIFFERENT HYDROGEOLOGIC SETTINGS
The rate, direction and distance of leachate travel from a landfill to an ultimate discharge
point will be largely determined by the hydrogeologlc setting. The leachate plume may be
confined to the landfill site or it may travel large distances; It may be divided Into multiple
plumes, move into different aquifers and reverse Its direction. It Is clear, then, that a
landfill monitoring program must account for all possible routes of leachate movement If
It is to be effective.
The following series of diagrams illustrate a number of hypothetical hydrogeologic landfill
settings. These diagrams are schematic and only intended to Illustrate general leachate
flow principals. Both the geology and hydrology of the settings are necessarily somewhat
simplified over most actual condition, however, the general principals Illustrated are still
valid. In addition, such complicating factors as differential attenuation of contaminants
by subsurface sediments and interference with leachate flow by production wells, have been
omitted. Clearly if all factors influencing leachate migration from a landfill were consid-
ered, the number of possibilities would be almost limitless. And, this is precisely the
reason why each individual landfill should be subjected to a hydrologic Investigation
prior to the establishment of a pollution abatement or monitoring system.
-------
LANDFILL
LAND SURFACE
(
FLOW
UNCATUKATED^^V, ZONE _^WATER TABLE
~*\
CLAY OR ROCK
Figure 1. A single aquifer with a deep water table. Leachates percolate vertically downward from the landfill
to the underlying aquifer and then moves downgradient as a bulb or plume in the direction of ground-
water flow. The mass of leachates may sink to the bottom of the aquifer if of a heavier specific
gravity, or float near the top of the water-bearing unit if the leachates are predominately hydrocarbon
in nature.
-------
'' '
, .' , ./LANDFILL
WATER TABLE-^_
- 'fT^p-TTV
/;-» ,. ' _ * /__* ' *^»
ROCK
Figure 2. Landfills located in stream-flat ground water discharge areas and within the zone of saturation
are always in contact with ground water moving from higher-land recharge areas to the stream
discharge point. In such cases, leachates are transported with the ground water to the stream
where it becomes diluted with normal stream flow waters.
-------
t * LANDFILL
FRACTURED ROCK
UNFRACTURED ROCK
Figure 3. Landfills positioned over fractured rock surface in a high water table area, permit leachates to
migrate downgradient along interconnected rock fractures to some lower natural discharge area
or a pumping well.
-------
FRACTURED ROCK
_ CLAY
Figure 4 - The landfill rests on a fractured rock surface with a deep water table. Leachate flows into
and through interconnecting fractures and discharges either at the surface as springs or into
the subsurface where it moves with the ground water to some more distant discharge point.
-------
LANDFILL '
i /
FLOW
/;/'/////////'"
\' / MARSH DEPOSITS'
1' //// /fPFAT) / ' '
WELL
ATTENUATION
OF
CONTAMINENTS
ROCK
Figure 5 - The landfill rests on a layer of marsh deposits (organic materials) underlain by an aquifer.
The water table is high and a mound is formed at the base of the landfill. Leachate mi-
grates downward through the marsh material to the aquifer. Some contaminants may be
attenuated within the marsh deposits. That portion reaching the water table moves
through the aquifer with the ground water to some surface discharge point.
-------
/// / V
LANDFILL /
ROCK
F'9ure 6 " The landf'H rests on a layer of permeable sand interbedded with clay lenses and underlain
by a clay layer. The water table is deep. Leachate percolates downward under the land-
fill, forming perched water tables and finally reaching the actual water table. A series
of leachate plumes flow around clay lenses with the ground water.
-------
,' /TV/—7 /
/LANDFILL '
PFPCIIL'D WATER
WATCR TABLE .
ROCK
Figure 7. An extensive perched water table is formed under the landfill. Leachate percolates to the perched
water table and flows downgradient to the end of the confining layer where it may again move down-
ward to the actual.water table.
-------
. • I I I T-~ I
• ''/','' ' '
'LANDF'lLL''/
----- CLAY
V.'MFR TABLE
{ GRAVEL
V^---T:^>—-
x-PERCHED
^ WATER TABLE
ROCK
Figure 8 - The landfill occupies an abandoned gravel pit with a clay layer at its base. A perched
water table (leachate) will mound up under the landfill and flow laterally through the
ground above the clay until it is free to percolate to the actual water table.
-------
,, -.
/ I ' I ' '
f f f' ' t', t
-ANDFILL
STREAM
STREAM
J',* '
-'.MARSH ^DEPPSjTS^ (PEAT), , _
CLAY
Figure 9. The landfill lies above organic marsh deposits bounded on either side by streams and underlain by a
shallow aquifer. Leachate from the landfill may move horizontally through the marsh materials to
the stream, or vertically downward with ground-water recharge to the aquifer.
-------
STREAM
WATER TARLF
——s
ROCK
Figure 10. The landfill rests on a single aquifer interbedded with clay lensed. The leachate plume is split into rwo
plumes by a clay lense. One plume discharges near the landfill while the other plume moves deeper in-
to the aquifer and flows to a more distant discharge point.
-------
LANDFILL'
AQUIFER
STREAM
CON
- *" /
X ,
\ \ v
_ <1 ' f
FIN IN1'"1-- \
! /•*
.^7~r
+-S
— x /
\"\"\"
' — ) "'"~" )
.,_ - — — ir~
-y xy
/' , /
\~x'X"
•^ -
~~ i
/ i
/}
.'
*\\
Dpn .
DC-L/
.^
\"
LOWER
AQUIFER
r\ ~\ \~
Figure 11. The landfill is situated over a two aquifer system with opposite flow directions. Lea chare
first moves into and flows with the ground water in the upper aquifer.: .Some of the leachate
eventually moves through the confining layer into the lower aquifer where it flows back be-
neath the landfill and away in the other direction.
-------
G^,
/
/ '/
LANDFILL
*
//
\ - \
^
/
\/'
/
•*
LAND SURFACE
- H WATER
' ~~~~ ^ 7---. TABLE
/ / , — — —
'
AFTFSIAN AQUIFER
.PIEZOMETRIC
J-Sfi-FACEOF
I.OVVFP UNITS
FRACTURED
ROCK
Figure 2
' The landfi" is situated over a three aquifer system and a deep water table. Leachate
percolates to the upper aquifer where it moves as a plume in the direction of ground
water flow. Eventually some of the leachate moves through the confining layer and
tnto the second aquifer that is an interconnected unconsolidated - creviced bedrock
water-bearing unit.
-------
r
'-'
DRAINAGE
TIL En
El
LANDFILL
/-DRAINAGE
TABLE
S.LTY CLAY
PEZOMETRIC LEVEL
CLAY
SAND
Figure 13. The landfill rests on a thick layer of clay underlain by an aquifer. Leachate is unable to penetrate
the clay layer and discharges to the surface tile drainage systems or drainage ditches in the area
i iL_ i__~ic:ll
around the landfill.
-------
/ //V'/
LANDFILI /
LAND SURFACE
X ~— — _ WATER TABLE
^ SAND
ROCK
Figure 14. The landfill rests on a single aquifer with a steep, shallow water table which intersects a portion of the
landfill. Ground water flows directly into the landfill forming leachate which then flows downward in-
to the aquifer as a plume.
-------
'/ / ' / LANDFILL
WAT I-1- —r —
TAT I r
SAND
(LEACHATE CONTAMINATED
FRESH WATER)
CLAY LAYER
(SALT WATER)
Figure 15 - The landfill is located near a large salt-water body. The leachate plume flows down into
the fresh water aquifer and toward the open salt water body. As the leachate plume reaches
the fresh-wilt interface, it is forced upward along the interface to discharge at or near the
edge of the salt-water body.
-------
5 MONITORING AND SAMPLING TECHNIQUES
5.1 ZONE OF AERATION
The zone of aeration is defined as the materials between land
surface and the water table. It is through these dry sediments
that percolating waters must move on the way to recharging, or
contaminating the ground water. In roost cases involving landfill
contamination, unless 1) scientific research is involved, 2) there
are unusual geologic or hydrologic considerations, or 3) extremely
toxic chemicals are suspected in the leachate. sampling in the
zone of aeration would not normally be carried out. Such
sampling is difficult and some of the methods are expensive.
However, when the decision has been made to monitor water quality
in the zone of aeration, the depth to water becomes important.
When surface active materials such as clay and silt are present,
attenuation will take place. Consequently, the chemical
quality of leachate just below the landfill may be many times
worse than that sampled at the water table. (See chapter 3.5 -for
a detailed discussion of attenuation)
5.1.1 Soil Analysis
Soil analysis can be valuable as a monitoring tool for tracing
leachate constituents, particularly those prone to cation
exchange or other adsorption reactions. Collecting soil cores
beneath the landfill can be done as part of a well installation
process. Techniques for core collecting are available (Hyorslev,
1965) , and methods for soil analysis are also documented (Black,
1965a, b; Hanna, 1964; Soil Science Society of America, 1971).
-------
Soil analysis has had only limited use in leachate
monitoring programs for seve'ral practical reasons. Probably
foremost is the lack of commercial soil testing laboratories
which can handle
-------
f~ 2.
soil tests outside the scope of agricultural application. For
example, testing laboratories are established in each state for
soil fertility analysis (nitrogen, phosphorus, potassium, pH),
but heavy metals, organic matter, and exchangeable cations are
not accomodated. In many places only noncommercial samples are
accepted by these labs.
Another restriction in soil analysis is inherent in the methodology.
What is actually analyzed is seldom the total soil, but instead,
a chemical extract of it. Fundamentally, a separation of the
inorganic/organic matrix and chemical species in soil solution
or "available" to soil solution must be made. An analysis of
the complete soil including the inorganic matrix would be
meaningless. To measure the chemical species in solution,
exchangeable to solution, available to plants, or accumulated by
adsorption or precipitation on the inorganic matrix is the
objective of the soil analyst. To meet this objective, soils
must be treated with reagents of differing chemical reactivity
under a variety of physical conditions. The resulting solutions
are then analyzed for the chemical species of interest.
Interpretation of results is a function of soil characteristics and
analytical methodology. Although methods have been standardized
to a degree, the analyst must be able to adapt and interpret
according to the dictates of the soil sample. In contrast, water
samples are usually analyzed directly or with a minimum of
pretreatment. This is not to state that there aren't analytical
-------
with water samples, but it takes an additional analytical
step to bring a soil sample to the same state that a
water sample is in when collected.
Soil samples yield information which cannot be obtained
from water samples. Therefore, soil sampling has a place in
the leachate monitoring program, and its incorporation should
be expanded. Chemical species associated with soil
solution as well as those on exchange sites can be traced
downward in a soil profile or in the unsaturated zone.
Locations of accumulation or leaching can be identified.
Sulfate (SO4 ), chloride (Cl ), and nitrate (NO^) are
soluble and unaffected by cation exchange reactions in soil.
This results in mobility impeded only by the restrictions
of water percolation. These anions can be analyzed for
in soil samples in addition to cations which are generally
more strongly associated with the solid soil matrix. The
latter present more difficult analytical problems because
they must be released from the soil matrix prior to
determination. However, locations of zones of heavy metal or
phosphorus accumulations can only be detected through soil
analysis.
In addition to the chemical information obtained from soil
core sampling, mineralogical information can be gained by as
simple a means as visual
-------
observation. Organic matter layers, clays, or silts nay be encountered.
Knowledge of their locations will aid ir. interpreting flow patterns and
checiical configuration in the pluae. If a siore sophisticated analysis is
da sired, s. necbanical analysis can be made relatively easily. It is sinply
a size fractionatioa of the soil into its respective proportions of sand,
silt, and clay. Even xsors elaborate x-ray crystallographic analysis of
clays -will identify the clay type. This latter degree of sophistication
is beyond the scope required for anything but a research progajp. on leach-
ate production and movement.
Advantages and disadvantages of including soil analysis in a monitoring
program are sucaarized below.
Advantages Disadvantages
1) Ease of soil sample collection 1) Constercial laboratories capable of
non-agricultural soil analyses are
2) Inexpensive saaple collection scarce
3) Accurate vertical and area! sarap^ 2) Hot a proven standardised saapliug
ling locations method for eonitoriKg progrsaa
**} Best nethod to measure leachate 3) Cost of analysis likely to be higher
attenuation through adsorption or per saaple than water because of
precipitation mechanisms * two-step analytical procedure
5) Long interval between sampling *0 Applicable nainly in the zone of
possible because of intermittent aeration
leachate production
5) Requirss special equipment for each.
6) In situ conditions of saatple can sample collection
be maintained with proper handling
6) Analytical nethods not adaptable
7) Physical and chemical conditions *» higa-rate standard procedures as
throughout unsatorated zone can be available for vater
observed
7) Results help interpretation of vatar-
8) Only part of total sample needs to quality data, but do not replace
be consuaed in analysis water-quality data
9) SaCTlos can be stared for later
comparison or further analysis
-------
Advantages Disadvantages
10} Mora representative biologi- 8) Wetting and drTing cycles, and
cal sampling possible than changes in redox poter.tal can
•with, water changa chsoieal reactivity of soraa
soil constituents after collection
9) Stats-cf-ti.3-art, not documented
in leachata studies
Decisions regarding adoption of soil sampling in a sionitoring prograa will
made on the basis of the following criteria.
1) Relative cost of soil analysis and water analysis fros the zone of
omsaturaticn.
2) Availability 'of analytical facilities.
3) Availability of analytical techniques for the parameters of
interest.
**•) Applicability of inforaation.derived to the conitoring progrsa.
5) Compliance with govermaeatal regulations govemiog monitoring
programs.
-------
Hanna, W. J. 196^. Methods for cheiaical analysis of soils. Pages
in Firaan E. Bear ed. Cheristrr of the soil. American Chesiical
Society Monograph Series !;o. 160. Reinhold publishing Co., 1,'sw York.
Soil Science Society of America. 19?1. Instrumental cethods for analysis
of soils and plant tissue. Madison, Wisconsin. 222 pp.
Black, C. A. ed. 19o5a. Mathoda of soil analysis, pare i. Physical and
nineralogical properties including statistics of r.easurscent and
sampling. Soil Science Society of Aeerica, Hadison, Wisconsin. ??0
pp.
Black, C. A. ed. 19o5b. Methods of soil analysis, part 2. Cheslcal and
microbiological properties. Soil Science Society of America, Kadison,
Wisconsin. 802 pp.
-------
REFERENCES CITED
1. Block, C. A. ed. 1965o. Methods of soil anal/sis, port 1. Physical and mi n era log-
ical properties including statistics of measurement end sampling. Soil Science
Society of America, Madison, Wisconsin. 770pp.
2. Black, C. A. ed. 1965b. Methods of soil analysis, part 2. Chemical and micro-
biological properties. Soil Science'Society of America, Madison, Wisconsin.
802 pp.
3. Hanna, W. J. 1964. Methods for chemical analysis of soils. Pages 474-502 ir^
Firman E. Bear ed. Chemistry of the soil. American Chemical Society Mongraph
Series No. 160. Reinhold Publishing Co., New York.
4. Hvorslev, M. S. 1965. Subsurface exploration and sampling of soils for civil en-
gineering purposes. Engineering Foundation, United Engineering Center, New York.
5. Soil Science Society of America. 1971. Instrumental methods for analysis of soils
and plant tissue. Madison, Wisconsin. 222 pp.
-------
5.1.2. Pressure Vacuum Lysiroeters
Methodology
Suction lysimeters have been used by a variety of investigators,
including engineers, soil scientists, and hydrogeologists, to
obtain samples of in-situ soil moisture. They are used
predominantly in the zone of aeration, but can easily be
used to sample ground water. This device, in its most improved
form, consists of a porous ceramic cup capable of holding a
vacuum, a small-diameter, sample accumulation chamber of
PVC-pipe and two sampling tubes leading to the surface. Once
the lysimeter is emplaced, a vacuum is applied to the cup.
Soil moisture moves into the sampler under this gradient, and
a water sample gradually accumulates. Then, the vacuum is
released and pressure is applied forcing the accumulated water
to the surface through the sampling tube. Construction,
installation, and sampling procedures are described by Grover
and Lamborn, 1970; Parizek and Lane, 1970; Wagner, 1962; Wengel
and Griffen, 1971; and Wood, 1973.
The technology of lysimeter utilization is well established.
They have been used to trace; pollution from septic tanks (Manbeck,
1975)y and cesspools (Nassau-Suffolk Research Task Group, 1969),
synthetic detergents (Department of Water Resources, The
ci fsi'i. '• ••• ~ "•
Resources Agency of California, 1963) /""the colliery spoil heaps
(James, 1974). Apgar and Langmuir (1971) used suction lysimeters,
wells, and soil samples to study the movement and chemical
characteristics of leachate from a landfill in centi \1
-------
Pennsylvania (Figure 5-1). There the water table is more than
200 feet below ground surface, and monitoring the unsaturated
zone is of great importance. To do this, the landfill
excavation was graded and lined so that leachate would drain into
a percolation trench along one side. The lysimeters were
installed underneath this trench. As many as four lysimeters were
emplaced at selected depths in a single borehole to a maximum
depth of 54.5 ft, each installation separated from the next by
a pelletized bentonite seal. Water samples collected from the
lysimeter network were analyzed for Eh, pH, temperature, specific
a
conductance, BOD, CJ, SO4/ total alkalinity, NH3, NO , NO3, PO4/
Ca, Mg, Na, K, and jTotal Fe. Apgar and Langmuir were able to
define differences in leachate concentration from upslope and
downslope cells as well as leachate attenuation and rate of
movement. Wood (1973) suggested a modification of the lysimeters
used by Apgar and Langmuir so that water samples could be
recovered from any depth (Figure 5-2). With this modification,
deep pressure-vacuum lysimeters appear to be the best method of
monitoring the zone of aeration because a check valve prevents
pressurization of the porous cups. Pressure exceeding about one
atmosphere in the sample chamber would drive accumulated
water back through the cup rather than to the surface in deeply
placed lysimeters.
-------
,} \. ,
• 2-V/cy Pump
su-n SL-T st-8 su-9 st-ii
C& vv>,<.\\ -. \ TV
/V v. \:>rv. r< -'^ ,./
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l-ltf
i -IT1
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:
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* * • " * "
- . - *.
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-7'
-28 S'
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1 REFUS
lu-^"
-2.3'
-10.3'
-20.S'
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E
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Croji section of
cell lysimeter netwoi;<.
"Tubinj"' Pceisure- !| ij
Vacuum in '""j 'j
:'i_ ' c £
I^fir-Cross-section of a typical pressuns-vacuum (ytimeter insul.'ation
•fiin>7)i.Wiih ih*i y MI in 11 nmmmigi JLidiahQ^Baania**4^'**^
V \ A- o
-------
y
•^
-------
~- 9.
Implementation
Parizek and Lane (1970) have described in detail pressure-
vacuum lysimeter installation and sampling procedures. The
following is excerpted from their report:
"A typical pressure-vacuum lysimeter installation is
shown in Figure 5-1. Placement holes are first drilled to
the desired depth. They may be 4 to 6 inches in diameter
depending upon the number of lysimeters to be placed in
each hole. A plug of wet bentonite clay is placed in the
bottom of the hole to isolate the lysimeter from the
undisturbed soil below it. This plug is optional. A layer
of "Super Sil" at least six inches deep, is placed on top
of the bentonite. "Super-Sil" is the trade name for a
commercially available, crushed, pure silica-sand of almost
talcum powder consistency. This is used to provide a clean
transmission medium for soil moisture moving under capillary
pressure, to insure hydraulic contact of the adjacent soil
medium with ih^Jre porous tip, to fill uneven voids created
during drilling, as well as to discourage clogging of the
ceramic tip by colloids, organic matter, or soil particles.
The lysimeter is placed in the hole to the desired depth,
and "Super-Sil" is placed around it until the lysimeter is
about half-buried. Native soil, free of pebbles and rocks,
is backfilled and tamped with long metal rods. After the
lysimeter is covered with about six inches of soil, a second plug
of bentonite is deposited to further isolate the lysimeter and
to guard against possible channeling of water down the drill
-------
hole. Backfilling is continued with native soil to the
depth where it is desired tp set the next lysimeter, at which
point the above procedure is repeated.
It was found that three lysimeters were the most that could
be conveniently placed in any one six-inch diameter hole.
If more than three were installed this led to difficulties
in proper depth placement, prevented proper tamping of
backfill material, added to the danger of crimping or
tangling the copper tubing and to the risk of channeling
soil water down the incompletely filled hole. Care was taken
to accurately measure the depth of placement of each lysimeter.
It was possible to set the lysimeters to within six inches
of the desired depth even in 30-foot deep holes.
After the lysimeters are placed, a short section of
flexible tygon plastic tubing is secured over the end of each
copper access tube with PVC electrical tape to allow
thumb-screw pinch clamps to be used to seal the lysimeter
between sampling periods, thereby maintaining the vacuum
within the lysimeter.
The pump used in conjunction with these pressure-vacuum
lysimeters is a two-way hand pump that can either deliver a
back pressure or pull a vacuum. This pump can be purchased
from any laboratory equipment supply house. The pump is
similar to a tire pump. It has a base on which the operator
-------
-11.
may stand while working the pump. A small vacuum gauge may be
installed on the vacuum part of the pump by means of a
tee-union. This enables the operator to consistently apply
a desired vacuum to all lysimeters (about 18 inches of mercury)
A length of tygon tubing is secured to each of the pump's
pressure and vacuum parts to allow the pump to be coupled to
the access tubes of the lysimeters. The free ends of the
pump's tubing are slipped over a short length of copper
tubing that is secured to the pressure-vacuum tube of the
lysimeter and is held securely by a small spring-loaded clamp.
A typical pressure-vacuum lysimeter sampling sequence is
as follows:
1. The lysimeter*s discharge tube is clamped shut and
the vacuum side of the two-way pump is attached to
the "in" tube.
2. A vacuum of approximately 18 inches of mercury is
drawn and the "in" tubing is clamped shut.
3. To recover soil water samples, the pinch clamps are
removed and the pressure side of the two-way pump
is attached to the lysimeter's "in" tube. A
few strokes of the hand pump generates enough pressure
to force the water out of the lysiraeter and into a
collection bottle placed under the discharge tube.
4. After emptying the lysimeter the discharge tubing is
clamped, the vacuum side of the pump is attached to
the "in" tube and the lysimeter is evacuated again
to gather another sample."
-------
-12.
Advantages and disadvantages of the pressure-vacuum lysimeter
are given below:
Advantages
1. Inexpensive sampling devics of
great reliability.
2. Inexpensive installation
3. Standard water analysis can be made
5. Samples can be collected at a
central point
Disadvantages
1. Moderately complicated
sampling procedure and
equipment.
2. Sampling device
failure is irrepairable
3. Small volume of sample
4. Surface tubing subject
to tampering unless
adequately protected
5. Use at depth greater
than 108 ft, not
documented
6. Sample contamination
by porous cup if
material is not
properly prepared
7. Possible plugging of
cup by colloidal
materials, and cup
might exclude large
molecules
-------
- I i. ••<•
REFERENCES CITED
1. Apgar, M. A., and D. Langmuir. 1971. Ground water pollution potential of a
landfill above the water table. Pages 76-94 in_Ground Water, Vol. 9, No. 6.
2. Department of Water Resources, The Resources Agency of California. 1963.
Annual report on dispersion and persistence of synthetic detergents in ground water,
San Bernardino and Riverside Counties. A report to the State Water Quality Con-
trol Board, Interagency Agreement No. 12-17.
3. Grover, B. L., and R. E. Lamborn. 1970. Preparation of porous ceramic cups to
be used for extraction of soil water having low solute concentrations. Pages 706-
708 [n_Soil Science Society of America Proc., Vol. 34, No. 4.
4. T. E. James. 1974. Colliery spoil heaps in_J. A. Cole, ed. Ground water pol-
lution in Europe. Water Information Center, Port Washington, New York.
5. Manbeck, D. M. 1975. Presence of nitrates around home disposal waste sites.
1975 Annual Meeting preprint, Paper No. 75-2066. American Society Agricultural
Engineers.
6. Nassau-Suffolk Research Task Group. 1969. Final report of the Long Island ground
water pollution study. New York State Department of Health, Albany, New York.
7. Porizek, R. R., and B. E. Lane. 1970. So! I-water sampling using pan and deep
pressure-vacuum lysimeters. Journal of Hydrology, Vol. 11. pp 1-21.
8. Wengel, R. W., and G. F. Griffen. 1971. Remote soil-water sampling technique.
Soil Science Society of America Proc., Vol. 35, No. 4. pp 661-664.
9. Wagner, G. H. 1962. Use of porous ceramic cups to sample soil water within the
profile. Soil Science, Vol. 94. pp. 379-386.
10. Wood, W. W. 1973. A technique using porous cups for water sampling at any
depth in the unsaturated zone. Water Resources Research, Vol. 9, No. 2.
pp. 486-488.
-------
r- 13.
5.1.3 Trench Lysimeters
Methodology
Several investigators have used trench lysimeters to sample
gravity water from irrigation or rainfall in the near-surface
zone of aeration. In normal practice/ a wood-reinforced
trlinch or concrete-ring caisson is installed to a depth of
10 to 30 feet below land surface. Pans (Parizek and Lane,
1970) , t*oughs (Olin Braids, personal communication, August
A
1975) , or, open end pipes (Nassau-Suffolk Research Task
Group, 1969) are forced out of the trench (caisson), through
access ports, into the subsoil. These collecting devices
intercept^ percolating gravity water and conduct it to sample
bottles inside the trench. Only after irrigation or precipitation
is there enough water infiltrating the subsoil to collect a
sample. Figure 5-3 shows an installation used to collect cesspool
effluent.
1
Due to the potential accumulation of hazardous gases generated
by decomposition of landfilled material, the use of an open
trench or caisson to sample leachate in or under a landfill
can be risky. Artificial ventilation and gas monitoring
devices are required to prevent injury to personnel collecting
samples inside the trench.
Implementation
A description of a typical tranch lysimeter is excerpted from
Parizek and Lane (1970). "A 4-foot wide, 12-fnt long trench
-------
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. WATER TABLE 23 -6" JUNE'63
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WATER TA3LE 2S'-5" DEC oo *••
~i55c£o£ - SecHon hhroug'n a cesspool and nearby sampling cnc.-n'asr showing th& lacaricr
of tsnsio.Tief'ers and grcvify samplers used to scmpie-. cesscoal effluenr in Lcr-
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.r- 14,
was excavated to a depth of 10 feet using a back hoe. The hole
was braced with timbers and siding to allow safe access to the
trench. The trench was then hand-dug to a 17 foot depth and
braced. The entire seepage face was inclined 1 to 5 degrees
from the vertical and sloped toward a hill down which soil water
and interflow was expected. The residual soil contained
resistant chert and quartzite cobbles and boulders and was
reasonably well "cemented" with iron-oxide and clay. As a
result, the pans could not be inserted into the soil profile
without first providing an opening. A sheet metal b.Slae 4 inches
wide and 2 feet long was hammered into the overhanging bank with
a sludge hammer to provide access for the pans. Pan lysimeters
were tapped into these openings and allowed to slope gently toward
the trench. Voids above and below the pans were back-filled with
/' w s-
soil andftamped into place. As siding was added to the trench
walls, holes were cut to allow the copper tubings to project into
the sampling pit. Spaces between the original trench faces and
siding were filled with native soil and washed pea-gravel to allow
water to flow freely toward the pit floor (Figure 5-4) . After the
f>SZ±:C.
walls and braces were emplaced, tyjge& tubing was connected to the
copper tubing and inserted into plastic sampling bottles. The
sampling pit was covered with a sloping roof and a half-round
drain pipe was /Sued to divert roof water away fron the
installation. A ladder was placed at one end of the house to allow
access."
An alternative method of construction is to place concrete manhole
rings in an open excavation or to sink them to depth using caisson
construction techniques, depending on soil stability. This
-------
2x12" Siiing eni
4x4* Tinbers. i'.l Wsod
TrtoUd with Pr*isr«:iv».
Gutter Cram
' Pip*
-fig.
Ooloraitl
Baiiroci
nf tn-TTi
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-------
- is.
type of construction is shown in Figure 3.
Trench Lysimeter Comparison Lysime.ter
Advantages Disadvantages
l.None 1. Dangerous because of
*vi
possible flamable gas
A
accumulation
2. Water will flow to
samples only after rainfall
3. Considerable expense
involved in constructing
trench or caisson
4. No documentation of
application to landfills
-------
REFERENCES CITED
1. Nassau-Suffolk Research Task Group. 1969. Final report of the Long Island
ground water pollution study. New York State Department of Health, Albany,
New York.
2. Parizek, R. R., and B. E. Lane. 1970. Soil-water sampling using pan and deep
pressure-vacuum lysimeters. Journal of Hydrology, Vol. 11. pp. 1-21.
-------
J- 16.
5.2 ZONE OF SATURATION
IP. the zop.e of saturation, leachate movement from a landfill will be
controlled by a combination of ground-water flow patterns and soil-
leachate interactions. Under shallow water-table conditions, only
a small zone exists where unsaturated soil-leachate interactions can
reduce leachate concentrations. Therefore, careful collection of
representative ground water samples from property constructed
wells is necessary to trace leachate movement or determine its
presence in the ground-water environment in which the landfill is
A
located.
cT'Jell Screened or Open Over a Single Vertical Interval
Methodology
Wells screened over a single vertical section of an aquifer, are the
most common construction used to obtain ground water samples from
unconsolidated sediments or semiconsolidated rocks. Uncased
wells (open hole) in consolidated rock can be used for the same
purpose. Although this type of well is routinely used in monitoring
ground-water contamination, including landfill leachate (Anderson
and Dornbush, 1968 and Fungar&li, 1971) a single well is not
particularly effective in providing information on the vertical
distribution of a contaminant. In practice, a well is drilled to an
arbitrary depth, usually just below the water table in landfill
studies, and the screen is set so that it intersects the water table
(Figure 5-5). The rationale for this type of construction isl^if
leachate reaches the ground water, it will be detected in water
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8
CEMENT GROUT 1-3 MIX,
OR BENTQNITE
I CASING - WHITE
PVC
C^-GRAVEL PACK
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LOTTED SCHEDULE
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S OR EQUAL)
F
rg j 5 FROM STATIC WATER LEVEL
;: ! TO BOTTOM CF SCREEN
. ,-^, ( r-r r. -,--'"-> "2* fT I %
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OBSERVATION"!-WELL
NOT TO SCAll
-------
~ 17.
samples from this type of well. However, this construction is
often used when leachatc has already reached the ground water.
The drawback of the construction is immediately apparent; only a
portion of the aquifer is sampled and only the most recently infiltrated
leachate can be collected. In most cases, leachate will be
denser than water and sink into the ground water under partial
control of a gravity gradient. This denser fluid body, "sinking"
into fresher water cannot be sampled with a well that skims only the
top of the water body. However, in the experience of the writer,
great reliance has been placed on this type of well construction
to trace the extent of leachate movement into an aquifer.
Even if the well is completed below the water table, it may not
provide water samples representative of leachate concentration at
that point. For example, the well casing may entirely seal
off the contaminated acquifer or the screen may penetrate into
another aquifer system (if little is known about site geology),
thus providing misleading water -samples. This drawback can be
partly counteracted .if the well is screened over the entire aquifer
thickness; however, if the aquifer is thick and the contaminated
plume is thin, the composite ground water sample that is
obtained provides no information on the vertical distribution of
leachate.
Taking everything into consideration, using a single-screen well
appears to be justified under two situation: 1) obtaining composite
ground water samples from wells in which the entire saturated
thickness of the aquifer is screened and 2) areas where depth to
?*•*
water is great and the majority of the sampling program is aimed
-------
at the zone of aeration and the top of the zone of saturation.
The latter case is probably the best use of this type of well.
The wells, completed in the upper zone of the water body, would
serve as an early warning system if any leachate is able to
percolate to the ground water. Once detected, other sampling
techniques would be required to trace leachate extent and
movement in the aquifer.
This type of well can be drilled by a variety of techniques,
including mud-rotary, reverse-rotary, air-rotary, jetting,
augering, and drive points; warfeh diameters rangia? from 1 1/4
inches to greater than but rarely exceeding 36 inches. The
drilling method chosen depends on: 1)nature of material to be
penetrated, 2) diameter and depth of well desired, 3) site
accessibility, 4) availability of drilling water, 5) budget
constraints, 6) time constraints and a variety of other factors
resulting from individual site conditions. Drilling methods per
se are discussed in a later section, but a summary is presented
in Table 1. With the possible exception of hand augering and
drive points, a drilling contractor should be used to install this
type of well unless the investigator has access to a power auger,
soil boring, or jetting rig.
-------
.> • / 6 fl
Weft -Is*; Serened Ove-f^a' Single ^Verti-fcal In.fer.fral-.
To be able to compare costs of the various techniques
described in Chapter 5.2.. A hypothetical aquifer is required.
For the purposes of illustration, a water-table aquifer
composed of unconsolidated sand with a depth to water of
10 feet and total saturated thickness of 100 feet will be
used. However, it should be realized that these cost estimates
are based on prevailing rates in the northeast and consequently
actual costs will be lower or higher^ depending on conditions
in the investigations' local area. Also, drilling and
materials prices have been climbing recently and the costs
presented here (Fall 1975) will no longer be representative
e£-aiLuul co&Ls in a very short period of time. In spite
of this, these estimates will provide an idea of relative
cost that should remain relatively unchanged by inflation^
etc. Table 1 is a summary of these costs.
As mentioned in Chapter 4.2, the recommended type of con-
struction for monitoring purposes is to screen the well
over the entire saturated thickness of the aquifer, which
** 1-
in our example is 100 feet. The quicktfesg and least
expensive way to complete this type of installation would
be to drill a 6- to 8-inch diameter borehole with a hydraulic
rotary rij to the bottom of the aquifer; set 4-inch diameter
-------
Table 1. Cost Estimates for Various Sampling Methods
Price Per Installation
Well Diameter
Sampling Method 2-inch 4-inch 6-inch
Screened over a single interval
(plastic screen and casing)
1. Entire aquifer $1,600 - $3,700 $2,300-54,500 $6,400 - $7,500
2. Top 10 feet of aquifer 650- 1,050 700- 1,150
3. Top 5 feet of aquifer with drive
point 100-200
Piezometers
(plastic screen and casing)
1. Entire aquifer screened
a. Cement grout 2,10Q - 4,700 2,800- 5,500 6,900- 8,500
b. Bentonite seal 1,850- 4,150 2,350- 4,950 6,650- 7,950
2. Top 10 feet of aquifer screened
a. Cement grout 1,150- 2,050 1,200- 2,150
b. Bentonite seal 900- 1,500 950- 1,600
Well clusters
1. Jet-percussion
a. Five-well cluster, each well
with a 20-foot long plastic
screen 2,500 - 3, 800
b. Five-well cluster, each well
with only a 5-foot long plastic
screen 1,700- 2,300
2. Augers
a. Five-well cluster, each well
with a 20-foot long stainless-
steel wire-wrapped screen 4,600- 5,300
b. Five-well cluster, each well
with only a 5-foot long gauze
wrapped drive points 1,800- 2,600
-------
Table 1 (continued). Cost Estimates for Various Sampling Methods
Sampling Method
2-inch
Price Per Installation
Well Diameter
4-inch
6-inch
3. Cable tool
a. Five-well cluster, each well
with a 20-foot long stainless-
steel, wire wrapped screen
4. Hydraulic rotary
a. Five-well cluster, each well
with a 20-foot long plastic
screen, casing grouted in place
b. Five-well cluster, completed in
a single large diameter borehole,
15-foot long plastic screens, 5-
foot seal between screens
Single well/multiple sampling point
a. 110-foot deep well with one-
foot long screens separated by
4 feet of casing starting at 10
feet below ground surface
Sampling during drilling
$ 9,850-$14, 150
$9,050 - $ 14,900 13,800 - 19,400
$4,240-$5,880 8,250- 11,000
3,000- 4,700
3,000- 4,700 3,300- 5,200
-------
plotted PVC well screen and PVC casing; backfill with a
gravel pack or formation stabilizer; and place a concrete
collar around the well casing at ground surface to prevent
downward leakage of rainwater or other fluids. Total cost
of this installation is in the range of $2,300 to $4,500
for drilling, materials, installation and development.
Screen is second only to drilling in terms of cost, running
from $1,000 to $1,500 for 100 feet of 4-inch slotted PVC.
Cosntruction cost could be reduced to a total of $1600 to
$3700 if 2-inch casing and screen are used, but sampling
can be more difficult in a well of this diameter. On the
other hand, using 6-inch casing and screen facilitates
development and water sampling but elevates the cost to
the range of $6400 to $7500 per well. In wells of this
size, wire-wound metal well screens are more commonly used
than PVC, resulting in a substancial cost increase per
installation as compared to the 4-inch well.
If the investigator is interested in sampling only the
top of the aquifer with a well constructed so that a 10-foot
long 4-inch diameter screen intersected the water table,
price per installation would range from $700 to $1200.
This is a substantial reduction in expenditure required
to monitor the ground water, but as discussed above, it is
-------
not a completely reliable technique for assessing ground
water contamination by leachate. Even greater reductions
in expenditure per installation can be obtained by installing
a 2-inch diameter, 5-foot long drive point by hand, total
cost of which would be less than ?200 per well including
labor, materials, and development with a pitcher pump.
-------
Table 1 - Summary Table of Drilling Methods
Rotary
Mud
Air
Reverse
Cable Tool
Jetting
Augering
Flight
Bucket
Drive Point
Depth
Shallow Moderate Deep
0 -200ft. 200-1 000ft 1,000ft
XXX
X X
X X
X X
X
X
X
X
Diameter
Small Moderate Large l'-
l-4in. 4-1 2in. 12 in'.'
XXX
X
X
XXX
X
X
X
X
'l'-
G
Lo'
X
X
X
X
X
Complexity of Operation
Moderate High
X to X
X to X
X to X
-------
jT- 19.
Advantages
1. Inexpensive
2. Small diameter, shallow wells
quick and easy to install
3. Can provide composite ground
water samples if screen covers
saturated thickness of aquifer
4. Can be drilled by a variety
of methods
Disadvantages
1. No information on
vertical distribution
of contaminant
2. Improper completion.
depth can give
incorrect picture of
leachate distribution
3. Construction method
can contribute to
vertical movement
of contaminant
-------
REFERENCES CITED
1. Anderson, J. R., and J. N. Dornbush. 1968. Investigation of the influence of
waste disposal practices on ground water quality. Water Resources Institute, South
Dakota State University, Technical Completion Report.
2. Furgaroli, A. A. 1971. Pollution of subsurface water by sanitary landfills. U.S.
Environmental Protection Agency Report SW-12g. 186pp.
-------
20.
Piezometers
Methodology
Although the terms piezometer and observation well are commonly
used interchangable, there is a significant difference between
them. As implied by its naitie, a piezometer is a pressure measuring
device, frequently used for monitoring: 1) water pressure in earthen
dams or under foundations, and 2) artesian pressure in confined
aquifers. The piezometer, a porous tube or plate in the former and
a screened well or open hole in the latter, is isolated from other
pressure environments by an impermeable seal of either clay or
cement. Water samples representative-of a specific horizon can be
obtained from well-type piezometers, a highly desirable factor in
designing a monitoring program (Figure 5-6). Piezometers can also
be used to measure vertical head differences under unconfined
conditions if the well screen is properly isolated by an impermeable
seal immediately above the screen. Any well constructed without this
seal cannot be considered a piezometer. However, there is a
significant difference in application to landfill leachate monitoring
between a piezometer and a well screened over a single vertical interval,
The relatively impermeable annular seal will prevent; downward
movement oc leachate into uncontaminated zones of the aquifer.
A low-ccst modification of a typical engineering piezometer will
allow collection of in-situ ground water samples throughout the
saturated thickness of an aquifer. The piezometer, on modification,
resembles the deep pressure-vacuum lysimeter described above (Figure
5-7). However, porous PVC is used instead of a ceramic cup, which
is not necessary and would, in fact, decrease the effectiveness of
-------
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INSTALLATION DETAIL
SLOTTING DETAIL
•Eif^te1 Piezometer installation for shallow ground-water
monitoring around sanitary landfills.
-------
Geraghty & Miller,
. . e*fiy) v
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-------
the sampler. With porous PVC, a vacuum applied to the sampling
chainber is immediately transmitted to the aquifer, drawing
water into it. & porous ceramic cup holds a vacuum and water
slowly moves through it, a characteristic necessary to collect
soil-water samples. Using porous PVC (or even slotted PVC)
should substantially reduce the cost of the sampler below
the approximately $30 charge for commercially available deep
pressure-vacuum lysimeters. The surface sampling procedure is the
same as that for a pressure-vacuum lysimeter.
Implementation
In order to place a grout or bentonite seal around a well
casing as required in piezometer construction, there must be
an annulus between the casing and the borehole wall. This
limits drilling methods to (1) cable tool, (2) one of the
rotary techniques or (3) hollow stem augering and a drilling
contractor will be required. After casing and screen have been
installed, a gravel pack is placed around the screen. To seal
the well casing, a neat cement grout or bentonite slurry is
poured or pumped into the annulus, thus preventing the
vertical leakage that might occur in the annulus if the well
is merely backfilled with cuttings or fill. This seal is vital
from a sampling standpoint, because the sample withdrawn from
the well is from a known vertical interval of the aquifer.
Without the seal, rainwater would infiltrate backfill, potentially
diluting samples collected from the well or leachate could move
downward, causing samples to be non-representative. Another
-------
-22.
consideration is that the seal tends to prevent downard
f\
movement of leachate in the annular material which may
act as a conduit to uncontaminated zones of an aquifer.
Constructing a monitoring well that contributes to
or hastens the spread of contamination is not a
recommended procedure.
-------
Piezometers.
Since piezometers and wells screened over a single interval
are the same except for an impermeable seal between the
casing and borehole wall, the only price difference will
be that incurred for placing the impermeable seal and purchase
of necessary sealing materials. In the hypothetical
aquifer, only a 10 foot seal is required and a two-man crew
Am
should be able to place it in half a day to a day. This
" t *
would increase installation cost about 500 to 1000 dollacs-
v/je
-------
Advantages
Disadvantages
1. Point sample is collected from
a known vertical section of
an aquifer
2. Construction prevents downward
migration of leachate in borehole
3. Can be installed inexpensively and
rapidly if casing diameter is small
4. Can provide composite ground-water
samples if screen covers saturated
thickness of aquifer
5. Modification of an engineering
piezometer will allow vertical
sampling of contaminant
1. Restricted number
of drilling methods
2. No information obtained
on artificial is «•' f/'f * t
distribution of
contaminant
3. Improper completion
. depth can give
incorrect picture of
leachate distribution
-------
REFERENCES CITED
1. Clark, T. P. 1975. Survey of ground-water protection methods for Illinois land
fills. Ground Water, Vol. 13, No. 4. pp. 321-331.
-------
5.2.3 Well Clusters
Methodology
The major drawback in using individual wells screened over
a short vertical distance of the aquifer is that they provide
no information on the vertical distribution of contaminant and
only rudimentary information on its areal distribution. To
•
overcome this, investigators (Pitt, 1974; Weist and Pettyjohn
1975; Aulenback and Toffenmore, 1975; Parlmquist and Sendelein,
1975; Fryberger, 1972; and Kimmel and Braids, 1975) have used
well clusters to define the vertical distribution of a
contaminant. Each cluster consists of a group of closely spaced,
small-diameter wells completed at different depths in an aquifer
from which water samples representative of different horizons
within the aquifer can be collected. Careful placement of well
clusters at the landfill site and its vicinity will allow reliable
delineation of both vertical and areal leachate distribution.
Well clusters are by far the most common and successful technique,
to date, for delineating ground water contamination. One short-
coming, however, is selection of the completion depth of each well
in the cluster. Several approaches to selecting this depth have
been made; 1) a pair of wells, one screened at the top, the other
at the bottom of the aquifer (Burt, 1972, and Geraghty fi> Miller,
1975); a three-well cluster, with screens set on the top, middle,
and bottom of the aquifer under investigation (Weist and PettiJohn,
1975); and 3) clusters in which the screened intervals are separated
-------
S-25.
by preselected intervals, such as the 10, 20, 30, 40, and 60
foot screen depths used by Pitt (1974) ; the 20 foot separation
from 20 to 100 feet used by Yare (1975) (Figure 8) , or
terminating 2 to 3 wells at 10-15 feet intervals as recommended by
Palmquist and Sendelein (1975). The fixed sampling depth, whatever
the screen placement selected, limits to some degree the usefullness
of the well cluster.
As pointed out by Yare (1975) , large vertical zones of an aquifer
would not be sampled, dependent on saturated thickness, even if up
•
to five wells are constructed in each cluster. Some uncertainity
will always exist as to the actual vertical distribution of
contaminant. Construction of more wells per cluster is not the
answer; only so many wells can be constructed close enough together
to represent vertical contaminant distribution at one point. In
addition, construction cost as well as the time required to complete
the cluster would become prohibitive. The only way to get a "true
to life" as possible picture of leachate distribution is to collect
ground water samples during drilling, a technique described below.
Implementation
Well clusters are easily installed, a major factor to be considered
when designing a leachate monitoring system. Normally, in
unconsolidated sediments, small-diameter steel casing (2-2 1/2 inches)
is driven by the jet drilling method to the desired depth and the
screen is set by the casing pull-back method or by augering a hole
-------
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DEPTH 63 FT.
CENTER WELL
PERIPHERAL WELLS
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-------
and forcing a well point to the desired depth. Alternatively,
a hole can be drilled or augered to a predetermined depth and
a common well point driven out the bottom of the hole into
undisturbed sediments. Either installation technique is
relatively rapid and inexpensive. For shallow aquifers (20 - 30
ft) , 1 1/4 inch well points can be driven by hand to construct a
cluster (Aulenback and Tofflemire, 1975).
Another approach to well cluster construction is multiple well
completions in a single borehole. This involves drilling a large-
diameter hole, either by a rotary technique or bucket auger, and
installing small-diameter wells to selected depths with each
screened zone isolated from the o'thers by an impermeable seal.
Meyer (1973) completed as many as 3, four-inch PVC wells in a single
22 inch borehole and Hughes and others (1971) install up to six
1 1/4-inch to 2-inch observation wells in one boring. This
technique for constructing wells clusters seems feasible provided
the cost of drilling large diameter boreholes is not prohibitive
and care is taken in placing the impermeable seals between screened
zones (Figure 5-9). A great advantage is being able to construct
the wells close enough together to get samples actually representative
of a single point (areally) in the aquifer, thus increasing the value of
the data obtained on water quality. If care is taken in constructing
the seals between the individual wells, such as using a shrinkage-
inhibitor in the cement grout, reliable samples of in-situ ground
water can be obtained, of course, the greater the number of casings in
f>
the borehole, the greater the liklihood of imperfect seals between
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the casings. To insure that the seals are effective, water levels
-------
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in wells not being sampled should be checked for sharp drops.
An abrupt drop would tend to indicate a vertical connection between
the screens.
-------
r-
Well CLu's£e.r"s
A variety of drilling methods can be used to install a
well cluster in the hypothetical aquifer; however, the best
method is jet-percussion because of the tight seal between
casing and formation and relatively low drilling changes.
This installation, consisting of a cluster of five wells
2-inch diameter with screens from 10 to 30, 30 to 50, 50
to 70, 70 to 90, and 90 to 110 feet below ground surface
would require an expenditure of $2500 to./3800. If only
5-foot long screens were centered around depths of 30, 50
70, 90 and 110 feet, the well cluster would cost $1700
to $2,300 to install. However, as discussed above, this
type of construction is not ideal because of the vertical
distances between the screened intervals through which the
plume of leachate enriched ground water might pass undetected.
Another way to construct well clusters in this aquifer
would be to use a power auger. In this method, a sediment
is loosened by a flight of augers and then a well point
and two-inch casing is pushed through the loosened formation
material to the desired completion depth. One problem
with this construction is the potential for vertical leakage
of water through the column of loosened soil around the
well casing. Another is that sturdy, screens must be used
in order to withstand the stress of being driven through the
loosened sediments in the borehole. In normal practice,
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r - 2 7 B
relatively inexpensive drive poi^t, five feet or less in
are used. However, to monitor the entire saturated thickness
of the hypothetical aquifer, five 20-foot long, stainless
steel wire wound screens with a drive point will be required,
considerably increasing total cost of the installation. An
augered five well cluster with 5-foot long, inexpensive
drive points should cost $1800 to $2600 while the most
effective installation from a sampling standpoint with five
20-foot long, 2-inch diameter stainless steel screens would
cost $4600 to $5300, a significant difference.
More expensive alternatives are drilling with either the
cable tool or hydraulic rotary method; the former costing
about $9850 to $14,150 per cluster of 6-inch diameter wells
and the lather from $13,800 to $19,400. The substantial
difference in these figures is due to the necessity of
grouting the annulus between casing and borehole wall in
the rotary drilled holes. Grout is necessary to prevent
vertical leakage of water through the annular material, into
the screen with leakage, samples would not be representative
of formation water in the screened zone. Because of the
seal between casing and borehole wall in a cable tool well,
grouting is not necessary. No substantial economies could
be obtained by switching to 4-inch diameter cable tool
holes. Drilling costs will be about the same as for 6rinch
-------
-T- Z
and the main savings would come fron using 4-inch stainless
steel wire wound screens rather than 6 inch.
An alternative to five individual well completions to
make a cluster is to install multiple casings in a single
borehole. This type of installation would cost.^8,200 to
^11,000 for five 4-inch diameter wells installed in
a 24-inch diameter borehole and in the range of $4240
to $5880 for five, 2-inch wells installed in a 12-inch
hole. Because of the necessity of forming a good seal
between each screen, 15-feet long screens will have to be
used in the hypothetical aquifer, which allows for a five
foot seal between each screened interval. As discussed
in Chapter 5.2.3, this seal is critical and if not properly
constructed, anjomalous water-quality samples will
result.
-------
r-28.
Advantages
1. Simple installation which does
not alv/ays require a drilling
contractor.
2. Excellent vertical sampling if
enough wells are constructed
3. Tried and true methodology,
accepted, used in most contamination
studies where vertical sampling is
required
4. Low cost if only a few wells per
cluster are involved, and drilling
contractor set-up for small
diameter wells can be found.
Disadvantages
1. Large vertical sections
of the aquifer are
unsampled. Artificial
constraint on data by
completion depths - what's
happening in unsampled
zones?
2. If jetting rigs or augers
are used, installations
are limited to 125 to 150
feet total depth and
installation is slow.
3. Small diameter wells can
be used only for monitoring,
cannot be used in
abatement schemes.
4. Difficult to develop and
sample if water level is
below suction lift in
small diameter wells.
-------
REFERENCES CITED
1. Aulenbach, D. B., and T. J. Tofflemire. 1975. Thirty-five years oF continuous
discharge of secondary treated effluent onto sand beds. Ground Wafer, Vol. 13,
No. 2. pp. 161-166.
2. Burtf E. M. 1972. The use, abuse and recovery of a glacial aquifer. Ground Wa-
ter, Vol. 10, No. 1. pp. 65-71.
3. Fryberger, J. S. 1972. Rehabilitation of o brine-polluted aquifer. U. S. Environ-
mental Protection Agency, EPA-R2-72-014
4. Geraghty, J. J., and N. M. Perlmutter. 1975. Landfill leachate contamination
in Milford, Connecticut. Consultants report submitted to General Electric-TEMPO,
Center for Advanced Studies, Santo Barbara, California.
5. Huges, G. M., R. A. London, and E. N. Farvolden. 1971. Hydrogeology of
solid waste disposal sites in northeastern Illinois. U. S. Environmental Protection
Agency, SW-12d.
6. Kimmel, G. E.f end O. C. Braids. 1975. Preliminary findings of a leachate
study on two landfills in Suffolk County, New York. U. S. Geological Survey
Journal of Research, Vol. 3, No. 3. May-June, pp. 273-280.
7. Meyer, C. F., ed. 1973. Polluted ground water: some causes, effects, controls,
and monitoring. U. S. Environmental Protection Agency 600/4-73-00Ib.
8. Palmquist, R., and L. V. A. Sendlein. 1975. The configuration of contamination
enclaves from refuse disposal sites on floodplains. Ground Water, Vol. 13, No. 2.
pp. 167-181.
9. Pitt, W. A. J., Jr. 1974. Effects of septic tank effluent on ground water quality,
Dade County, Florida. An interim report. U. S. Geological Survey, Open-file
report 74010.
10. Weist, W. G., and R. A. Petfijohn. 1975. Investigation ground-water pollution
from Indianapolis landfills - the lessons learned. Ground Water, Vol. 13, No. 2.
pp. 191-196.
11. Yore, B. S. 1975. The use ofa specialized drilling and ground-water sampling
technique for delineation of hexavalent chromium contamination in an unconfined
aquifer, southern New Jersey Coastal Plain. Ground Water, Vol. 13, No. 2.
pp. 151-154.
-------
5.2.4 Single Well - Multiple Sample Points
Methodology
In order to sample multiple horizons in a single well, screens
or casing perforations must be constructed at regular intervals
in the well. Spacing will depend on the sample density required
and construction expense; the greater the number of open zones, the-
higher the well costs. The California Department of Water Resources
(1963) successfully obtained closely-spaced ground-water samples
by perforating steel casing with a mechanical perforator at set
intervals in the well isolating each set of perforations with
inflatable packers, and pumping the isolated casing segment with a
submersible pump (Figure 5-10). The attractiveness of this type of
sampling operation is apparent. However, there are some pitfalls.
Care must be taken to insure that the packers are isolating the
sampled section of screen and that no water from above or below is
leaking past the packers, contaminating the sample. Also pumping
rates must be kept low to insure that formation water is drawn from
only opposite the isolated section. Higher pumping rates will induce
flow from horizons above and below the level of the aquifer being
sampled, resulting in an unrepresentative sample. If the annulus
between the casing and the borehole wa&e backfilled, the possibility
.-..*
of vertical movement of water in the annular area, exists1.
Therefore, there is no guarantee that a sample does not contain water
from a lower or higher horizons' which has moved through the annular
material under the influence of the pumping gradient. To
adequately protect against this type of sample contamination, an
impermeable seal of either bentonite or cement grout should be
-------
SUSPENSION CAQLE
AIR LINE
PACKERS 18 C.C
DISCHARGE LINE
BAND
RUBBER,INFLATED
RUBBER, DEFLATED
CASING
ERFORATIONS
INTAKE
V
\ •>
:. v ViO
V-v-,.
-------
^30,
placed between every screen or slotted interval. This may not be
possible with closely-spaced screens or casing perforations. A well
Aftt'J-''i$ ~fc "f/'fje "t-ft ' •ti'ee.'ft'e -if
constructed and sampled ^^^-'KJ into arrovmt the* ftTwv.y will provide <*
excellent^ samples' af the vertical distribution of a contaminant.
Another approach^ for shallow vertical sampling using a singlg
is that described by Hansen and Harris (1974). They isolated fiberglass
probes at regular spacings inside an 1 1/4 diameter well point (Figure
11) . Samples were drawn to the surface through a tube attached to the
fiberglass probe after the well point was driven to the desired depth.
This type of construction is inexpensive and can be "homemade" with
little difficulty, but will only allow collection of samples from
depths less than sjerction limit about 30 ft, at sea level.
Implementation
Installing a multiple sampling point well will require the services
of a drilling contractor unless the device dejcVribed by Hansen and
Harris (1974) is used. This is essentially a drive point which could
be driven by hand to depths of about 30 feet. On the other hand,
multiple screen or slotted casing installations require the skills of
a well driller. For one thing, a large-diameter open borehole in
which casing can be set is needed, necessitating a cable tool or rotary
rig. Six-inch diameter or larger casing should be used in order to
accomodate the packer pump unit which in turn requires a tripod winch,
-------
1/4-INCH O D TUBING
SOIL SURFACE
PIPE EXTENSIONS
WATER TA3LE
777777W777777
1/4-INCH
CAULKING HOLES
t.l/4-IMCH \
WELLPOINT;
PROBE SPACING
AND WELL POINT
LENGTH ARE
OPTIONAL
/ff/7/7/7777^
SAMPLE COLLECTION FLASKS
777/777/777
TU31.NG FROM1,
LOWEST PRO3=:
SAftOMATftlX
CAULKING
Fig. 1L Construction details of the groundwater profile sampler.
r-//
-------
po-.ver and air supply. If sceel casing is not slotted before
installation, a special down hole tool is required to make the
slots. Skill and equipment requirements for this type of
installation therefore necessitate use of a drilling contractor.
The packer/pump is not quite so formidable. Once a good quality
submersible pump has been obtained, local investigators or a
machine shop can equip it with packers. Cherry (1965), has described
the design and operation of a rather elaborate packer pump (Figure
F-12).
-f-
I "This sampler collects a pumped sample of water from a specific
zone in an uncased or multi-screened well. Minor modification
of the sampler permits remote measurement of several chemical and
physical characteristics of the water in the zone being sampled. The
sampler can be used in wells with diameters of 8 to 16 inches,
inclusive, which do not contain pumps, pipes or other obstructions.
It is suspended on a cable from an A-frame, and is raised and
lowered by an electric motor that is powered by a 110 volt
a-c portable generator. This generator also runs the electric
pump which is part of the sampler.
The sampler consists of two inflatable packers or boots - one mounted
above the submersible pump and other below it. When the boots are
inflated, the zone between them is isolated from the remainder of the
we] 1 and water can be pumped from this isolated zone.
-------
Option*!
prvisurr
indicators
Fill Drain Pump Main
vatve vatv»
1. Metal plat. '
2.'Wp«.. ;
3. Electric cable
4. Inflatable boot (rubber)
5. Pipe (to inflate boQt)
6. Plp» (connects two boots) '
7. Submersible-pump irrtjke
E. Pressure sensor
9. Electric till valve (normally closed)
10. Electric drain valve (normally open)
H. Pressure-relief valve (optional)
12. -Flow-regulation valve
NOT TO SCALE
SIDE VIEW
FIGURE 1.—The Casee sampler.
lNS-ntccno:
-------
.r- 32.
The capacity of the pump is about 15 gallons per minute. The
spacing of the boots can be varied by using different lengths of
connecting pipe between them. The minip.uzv spacing of the boots is
5 feet (length of pump) . The boots are inflated by pumping water into
them, from the well, through an electrically controlled valve; they
are deflated by pumping the water out of them through another
electrically controlled valve. Advantages of this sampler over
other packer-type samplers are its portability, the ease with which
it can be repositioned without removing it from the well, and the
fact that it is relatively inexpensive.
Instruments to measure temperature, specific conductance, or other
chemical or physical characteristics of the water in the well can
be placed in the space between the boots. Experience has shown,' that
continuous measurement of specific conductance, in this way, is
very useful in determining the proper time to collect the water
samples. It is desirable to pump from the well a volume of water
equal to at least 3 times the capacity of the discharge line and
isolated section before collecting samples for analysis, in order to
ensure the collection of representative samples."
The packer/pump shown in Figure 10 is less elaborate and more amenable
to fabrication without the facilites of a machine shop. Although
actual construction is not described in the California Department of
Water Resources report, it seems that two rubber diaphr^fiis possibly
cut from tire inner tubes, were clamped, probably with stainless
steel hose clamps, to the exterior of the pump. An air line to the
surface allows inflating or deflating the packers. If only shallow
Is
sampling depths are involved, "home made " diaphrams and valves should
-------
f-33-
/"» r.™ =T"
-r £* ,v- 0
ti 'A i—a U u
take the inflation pressures required, greatly reducing fabrication
costs of the packer/pump.
-------
T
a
Single WeLl'/Mu-rtiple^Samp Xing ^.Points
','•••
Perhaps the easiest way to construct a well capable
of being sampled at set intervals within the casing is to
use 6-inch PVC casing, slotted PVC screen, and glued-
joint couplings. The screen sections of set length can be
separated by the appropriate lengths of blank casing using
only a handsaw to cut the lengths and PVC cement to join
them together. This construction can be done rapidly and
easily by hand, with simple tools and little skill. A
well in the hypothetical aquifer, with one-foot long screen
sections separated by four feet of casing would cost
$3000 to $4700 to install. Steel casing and screen would
be considerably more expensive to assemble in this manner,
and therefore casing perforation is necessary. The cost
of casing perforation will depend on how familiar a driller
is with performing this operation and whether or not the
equipment is readily available.
The pump/packer assembly necessary for sampling could be
fabricated for $1000 to 2000 or more depending on the pump
used and how elaborate the packer system is. Portable
generators cauble of supplying the power necessary for the
pump can be purchased for several hundred dollars. Although
these prices seem steep, they are one-time cost and with
proper care and maintenance the pump/packer system should
last years.
-------
o A ^ T
in, : -L 'j :•:
- 34,
Advantages
I. Excellent information on vertical
distribution of-, contaminant.
2. Well diameter is large enough
to use in a pumped withdrawal
program, if necessary
3. Water samples representative
of specific horizons within
an aquifer can be collected
4. Sampling depths only
limited by size of
sampling pump
5. Rapid installation possible
Disadvantages
1". 'Expensive
2. Proper well construction
and sampling critical
to successful application
"3. Complicated sampling
procedure involving a
a great deal of
equipment
-------
- I
REFERENCES CITED
1. Deportment of Water Resources, The Resources Agency of California. 1963.
Annual Report on dispersion and persistence of synthetic detergents in ground water,
San Bernardino and Riverside Counties. A report to the State Water Quality Con-
trol Board Interagency Agreement No. 12-17.
2. Cherry, R. N. 1965. A portable sampler for collecting water samples from specific
zones in uncased or screened wells. U. S. Geological Survey, Professional Paper
525-C. pp. C214-216.
3. Hansen, E. A., and A. R. Harris. 1974. A ground water profile sampler. Worer
Resources Research, Vol. 10, No. 2. p. 375.
-------
J-- 35.
- Sampling During Drilling 1~*>v i- '^ ,„• • :'. ." _;
Methodology
A major disadvantage of the sampling techniques described
above is that a constraint is placed on the data obtained
from the ground water samples by the fixed or arbitrary
point at which water samples are collected. In other words,
"blind" placement of wells can result in a false representation
of contaminant distribution if it is not uniformly dispersed
throughout the aquifer at the sampling point. Contaminants
are often stratified; underlain, overlain, or interfingering
with uncontaminated ground water. To define these
relationships adequately, information on the vertical
distribution of contaminant must be obtained prior to
installation of the monitoring well. This information can
be obtained by formation water sampling during drilling.
Several researchers have successfully obtained in-situ ground water
samples during drilling using three basic techniques: 1) driving
a casing (Fryberger, 1962), or well point (Childs and others,
1974) to the desired depth and bailing or pumping a water sample
from that depth, repeating the process to completion depth or
refusal; 2) drilling a mud rotary hole to the sampling depth,
pulling the drilling string, setting and gravel packing a
temporary well screen, and pumping a formation water sample.
Yare, 1975); and 3)drilling a borehold to the desired horizon,
setting a cone packer and riser pipe into the smaller hole and
-------
•- 35.
_ Sampling During Drilling '•'sf ** '± «''~\V .; j
Methodology
A major disadvantage of the sampling techniques described
above is that a. constraint is placed on the data obtained
from the ground water samples by the fixed or arbitrary
point at which water samples are collected. In other words,
"blind" placement of wells can result in a false representation
of contaminant distribution if it is not uniformly dispersed
throughout the aquifer at the sampling point. Contaminants
are often stratified; underlain, overlain, or interfingering
with uncontaminated ground water. To define these
relationships adequately, information on the vertical
distribution of contaminant must be obtained prior to
installation of the monitoring well. This information can
be obtained by formation water sampling during drilling.
Several researchers have successfully obtained in-situ ground water
samples during drilling using three basic techniques: 1) driving
a casing (Fryberger, 1962), or well point (Childs and others,
1974) to the desired depth and bailing or pumping a water sample
from that depth, repeating the process to completion depth or
refusal; 2) drilling a mud rotary hole to the sampling depth,
pulling the drilling string, setting and gravel packing a
temporary well screen, and pumping a formation water sample.
Yare, 1975); and 3)drilling a borehold to the desired horizon,
setting a cone packer and riser pipe into the smaller hole and
-------
f- 36.
A
r
pumping a sample (Harden, personal corr.T.unication, 1974).
If proper precautions are taken, formation water samples
collected using these techniques will be representative of
water quality at a known vertical interval of the aquifer.
The critical factor in successful application is developing
the temporary well to the point where all traces of drilling
fluid have disappeared from the pumped water before a sample
is collected. Dilution of the sample by the drilling fluid
and contributions of chemical constituents by clay particles
in the mud will produce erroneous and erratic data, and little
information will be gained on the actual vertical distribution
of contaminant.
The main advantage of this type of sampling is that the top,
bottom, and internal stratification of the contaminated slug
can be defined with reasonable accuracy prior to setting a
permanent casing and screen. With this information, the well
can be designed for the most advantageous sampling and/or
withdrawal of the contaminant at that point in the apfquifer.
Then, changes in the vertical distribution can be monitored
very closely.
Implementation
Yare (1975) used a ground-water sampling during drilling
techniques in the course of investigating a hexavelent
chromium contamination problem. A borehole was drilled with a
hydraulic rotary rig and drilling mud was made wi.th an organic
-------
UKAH" ""•
base drilling fluid additive^- ^In order to minimize the effect
of drilling fluid on the formation water. A slotted PVC screen
attached to a riser pipe was lowered to the bottom of the borehole
packed with fine gravel. This, in essence, formed a well in the
borehole.
After the gravel had tine to settle through the drilling mud
and around the screen,\well was pumped until no further traces
A
of mud could be detected. By this time, an effective filter
cake had formed on top of the gravel pack, isolating the screen
from the fluid in the borehole and the filter cake between the
gravel and the borehole wall broke down because of the pumping
gradient. To insure that formation water was collected, an
additional 100 gallons of water were pumped before sampling. In
this formation, the effective radius of the well was estimated at
2 feet.
The drilling and in-situ water sampling procedure which evolved
from this investigation consists of the following steps as shown
diagraiamatically in Figure 5-13:
1. drilling an eight-inch diameter borehole to the
sampling horizon;
2. pulling the drill string and replacing the bit with
a five-foot long, four-inch diameter wire-wound well
screen;
3. lowering the screen and drill string to the bottom of
the hole and gravel-packing with number 2 gravel to
cover the screen;
4. attaching a gasoline-powered centrifugal pump to the drill
string and pumping until the drilling fluid level
-------
DRA
si»»x u s\ y^A
j iJ
-JO
* _n_«**Tfl.
1 :
Ij
I (
Ji
fH.T£R .
''CAKE •
V-eLL •
; t SCREEN^
fi|
r
{
li
D3K.L
"StUMi
CRAXSL
• rec*.
~"1
i
If
u
1
SiJ. W4T2R
PACK
STEP I STEP2 STEP3 STEPSA.&5 STEP 6
Jn-situ ground-water sampling procedure.
VC'.' •
-------
A r
>-! 3*
stabilizes in the hole and the discharge clears
of drilling fluid (in this case, a centrifugal
pump could be used because static water levels ranged
from 6 to 12 feet below ground surface);
5. pumping at least 100 gallons of formation water before
collecting the sample; and
6. pulling and removing the screen, then lowering the
bit and drill string, and drilling to the next sampling
horizon.
Harden (personal communication, 1974) described a sampling
during drilling technique useful in the deep holes in consolidated
sediment or rock. In this method, the original hole drilled
is 6 3/4 inches in diameter. When the hole penetrates about
15 feet to 30 feet into a sand from which a water sample is
desired, drilling is stopped (step 1 in Figure 14) , and the
hole is reamed to a diameter of 9-7/8 inches down to a point
just above the zone selected for water sampling. Then the
original 6-3/4 inch hole is washed out to its original depth,
(step 2 in Figure 14) and a string of pipe with packer and
screen is set in the hole, as shown in step 3 of Figure 14. The
pipe is usually 4 inches in diameter, and the packer is a
commercial rubber cone type, with typical dimensions of 6 by
9 by 14 inches. Often a canvas "shirt tail" is wrapped by the
packer to assist in sealing. The packer is set on the shoulder
between the 6-3/4 inch and the 9-7/8 inch portion of the
hole. Below the packer a commercial 4-inch water well screen
10 to 20 feet long is attached to the 4-inch pipe. After
the packer is seated, the temporary well is developed by
airlift for several hours until the water becorr s clear. After
-------
A-
w«p.
J ****' '.
»
"*•*•• ~-'
-sj-.r-_^
'-'."--'}
IS-
CM-.
:-_-^,,'
•-~-"-=
—.J.
tar Sampling
From Test Hole.
-------
.r-39
P^ r^ A T' -T
\^£ • " •'_ ._\ .'' j|
' '
this the air/line is removed from the 4-inch pipe, and a
small diameter turbine or hi-lifc pump is installed and the
temporary well is again pumped until i_ho water becomes clear, after
which the final samples are taken.
At the end of the pumping, the casing and screen are then pulled
from the hole, and drilling of the 6-3/4 inch hole is resumed
until a second water-bearing zone is encountered from which a
water sample is desired, at which time the entire water-sampling
process is repeated.
Advantages Disadvantages
1. The best technique currently
available for defining vertical
distribution of contaminant.
2. Completed well can be used for
water quality monitoring and/or
pumped withdrawal of contaminant.
1. Considerable expense
per well.
2. Requires a knowledgeable
drilling contractor
and careful supervision
of the drilling and
sampling.
,-.---
Pore Water Extraction from Core Samples
pt» • ! - •
-------
.-T-V „.
; ,) f\
sampling ourang fc "
The most efficient technique for sampling the- hypothetical
aquifer described in 5.2.1 is to use .the technique described
by Yare (1975). If this method is used, 10 samples can be
obtained at depths of 20, 30, 40, 50, 60, 70, 80, 90, 100
and 110 feet below ground surface and five of the most
contaminated intervals of the aquifer can be screened with
5-feet long, 4-inch plastic screens for a total cost of
$3000 to-?4700. Additional sample points would cost $125 to
$200 each. These screen segments could be sampled with a
packer/pump or by installing and isolating a deep pressure/
vacuum lysimeter in each screened interval. If a packer/
pump is used, 60 inch casing is necessary and total cost
per installation would be in the range of $3300 to $5200.
Lysimeters could be placed for approximately $100 each.
-------
REFERENCES CITED
1. Childs, K.E. t S.B. Upchurch, and B. Etlis 1974. Sampling of variable waste-migration patterns
in ground water. Ground Water 12 (6): 369-376.
2. Fryberger, J.S. 1972. Rehabilitation of o brine-polluted aquifer. U.S. Environmental Protection
Agency. EPA-R2-72-OU.
3. Harden, R.W., Denver, Colorado, Personal Communication, 1974.
4. Yare, B.S. 1975. The use of a specialized drilling and ground-water sampling technique for
delineation of hexavalent chromium contamination in an unconfined aquifer. Southern, New
Jersey Coastal Plain. Ground Water 13 (2):151-154.
-------
l-rV ? •?, :••„ y
H x^ $^\ a y
and Gill and others, 1963). A major problem with this technique,
is determining the amount of drilling fluid invasion into the
core during the process of driving the coring device and bringing
it to the surface; the greater the invasion, the less reliable
the water-quality data obtained. Sand and gravels are more
readily invaded than finer grained sediments.
Luscynski (1961) overcame this problem by putting fluorescein
dye (green color) in the drilling mud. Any penetration of drilling
mud into a core sample would be shown by the green dye, and
the uninvaded core sections could be selected [r^o extraction. Thus,
quantitative chemical analysis could be assured because dilution
of pore water by drilling fluids would not be a factor. Unfortunately,
on completion of drilling, disposal of the bright green drilling
mud is a problem (John Isbister, personal communication, 1975).
Normally, drilling mud is just dumped on the ground and is
eventually eroded away. Because of its natural gray or brown color
it is not very obvious. The bright green mud would be a definite
eyesore/"'and would probably have to be disposed of by burial at the
site - no real solution.
Low permeability, porous, saturated sediments will retain most
or all of their interstitial water during core sampling. Walker
and others (1972) used this sediment characteristic to advantage
in tracing a bulb of nitrate-contaminated ground water at an
Illinois farm underlain by loess (Figure^ 15). The cores were air
dried, leached with water, and the solution was analyzed for
nitrate-nitrogen. Because of the nature of the sediment, Walker
and his co-investigators were able to trace the contaminant bu'b. Under
-------
a.lUi'if. - FARMSTEAD SOIL KITWTE CCNCtWKATKW AS} OIS7AIMTICM
%
V •' ... —
-.
-------
i-«i . L ^-A ;• -\ /* pra ^--
UK AS- I
different soil conditions, such as sand and gravel, this technique would be less applicable
because little interstitial water is trapped in the core sample. In this type of sediment
the solution collected from leaching the air dried samples would primarily represent
adsorbed constituents whose concentration would depend on the chemical activity of
the soil.
Implementation
I
*•»** (pie filter press used; Luscynski (1961) describes in detail using a fi her press to extract
—
pore water, is one of several types sold commercially for use in determining filtration
properties of drilling muds. The unit consists of a chcnbdr, a filtering medium, a
graduated tube for catching and measuring the filtrate, and a pressure-source unit. A
cell, base cap. screen, rubber gaskets, and top cap make up the chamber. The cell
is 3£ iric nes high and has inside and outside diameters of 3 and 3£ inches,
respectively. The filtering medium is a sheet of filter paper which fits on the screen
over the base cap; it* has a filtering area of about 7 square inches. The filter paper used
is specially hardened to withstand the pressure in the chamber. A graduated cylinder is
used to catch the filtrate.
Uninvaded cores consisting of loose material such as sand and gravel are transferred to
the filter-press chamber by spatula or spoon. Usually it is not practical to remove much more
than 25 to 50 percent of the uninvaded material from the core barrel by this method.
Enough material is transferred to fill the chamber about a quarter to half full. It is then
tamped lightly until an integrated unit is formed in the chamber and a film of water is
-------
r- «..
n
formed on the surface of the material and along the cylindrical wall. '
Usually less than 10 to 20 percent of a solid-brs^ilry-clay sample is invaded by the
drilling fluid. Plugs of the uninvaded material I to 2 inches long are placed in the
chamber to fill It about a quarter full. Then they are molded and tamped into an
integraded unit. Difficulty can be experienced in molding and tamping a relatively
dry solid clay-one having a water conrent-of less than-15 to 20 percenfof the dry
weight of the clay.
The total time between the opening of the spliKspoon core barrel and the placing
of the chamber In the frame is usually I to 2 minutes for the' loose 'material and 2
to 5 minutes for the tight ma'terlalV Tbei;e is thus, very little opportunity for
evaporation.
After a sample is properly prepared for filtration, the chamber is fully assembled,
placed in the frame, and made airtight J>y_the_T -screw (Figure' 1£). The gas pressure
is then applied.
The pressure of the carbon dioxide gas in the chamber moves some of the interstitial
water through the filter screen and filter tube into the graduated cylinder. Pressures
of 5 to 30 psT suffice for the gravel, sand, and silt samples. Pressures of about 100 psi are
usually sufficient for silry and solid clay samples. The carbon dioxide gas does not alter
the chloride concentration of water forced from the material into the filtrate tube.
-------
AFT
G»AOU*ltO CWMOtt
FICCII 1.—Filter prtM and cbaalitr a*»*mMjr. Conrtnr or Eaciod DirUloo.
b\
-------
•
Chloride determinations of the filtrate are made in the field by the standard titration
method using silver nitrate solution. Relatively large amounts of filtrate (25 to
50 ml) are needed when fresh water is to be tested, and relatively small amounts
(I to 10 ml) when salt water or diffused water is to be tested.
Usually enough filtrate can be obtained from the uncontaminoted material of only
one core if its taken in a diffused-water or salt-water zone. However, more than
one core may be necessary to obtain the required amount of filtrate if the core is
taken in a fresh-water zone; this is particularly.true for solid-clay samples, which
XJefd only small amounts of interstitial water."
An alternative to the mud filter-press is to fabricate a core sample squeezer which
utilizes a hydraulic ram, as described by Manheim (1965):
/I*"""
1st "The squeezer utilizes a commercially available cylinder and ram (made by the Carver
Co., Summit, N. J.) to which a machined base with a filtering element and fluid
outlet is fitted. Construction details are shown in Figure 5-17. The filter unit
consists of a stainless steel screen and a perforated steel plate contained in a circular
recess in the steel filter holder. Alternatively, a porous (sintered) metal plate may be
used to replace both screen and perforated plate. The top surface of the filter should be
flush with the other rim of the holder so that it may support one or more paper filter
disks. Finegrained, hardened laboratory filters give a visually clear effluent, but
membrane or microfilters may be used to assure maximum freedom from suspended matter.
The lower part of the filtering assembly, fitted with a rubber washer, protrudes into a
recess in the steel base; when pressure is applied the gasket is squeered against the
cylinder and prevents leakage of water around the filter unit. The space in the recess
-------
?'*
ft ?
y M #$ £.
J IXMl S
(Alter p»t>*r support) (i>
inl*si st*«i »i/*-jcr
dijk. Jj-in H-ck (3)
. r i I *— Ernutnt ^a^iaA* r*»m«o
y | | I to fit no** of Cyrix** U I)
Syf r>z* CD
',±lcpn1i"r—Drawing show-ins components of bydrsulic
squwsrer. Ail dimensions in incaes. (Biie ii about
2>i iachea in height.)
\.c
U i. \ 7
-------
J--44.
!' ""^ ''"^ f\ r*
•' -1 i '' /' \
ond the diameter of the outflow boring are kept small so that little fluid can collect in
the squeezer itself. All metal parts in the filter base are made of Iron and Steel
Institute No. 303 stainless steel. Rubber and teflon disks just below the piston prevent
loss of fluid upward when pressure is applied. The rubber,teflon, and filter-paper disks
ore punched out with an arbor punch and can be made as needed.
The present design permits insertion of a disposable syringe (preferable1/ plastic) directly
into the base of the squeezer to receive fluid. The narrow effluent hole is reamed out
to permit fitting of the standard 'Luer1 taper of the syringe nose.
A larger squeezer has also been constructed using a 2£ - inch Carver cylinder and
piston. The design is similar to that shown in Figure 5-16, except that the filter plate is
increased in thickness to give greater strength. The effluent line remains small. Because
the cross-sectional area of the cylinder bore of the small squeezer is about 0.88
inch, a 10-ton laboratory press exerting its maximum load of 20,000 pounds will apply
a pressure of about 22,000 pounds per square inch to the sediment. However, a
20,000 Ib load will apply only about 5,000 psi in the large unit. The large squeezer
should therefore be used with a higher capacity press when more compact sediments are to
be squeezed.
In sequence, the steps in squeezing a sample are as follows: The filter holder with its
gasket Is placed in the recess of the filter base. The screen, perforated plate (or porous
disk) ond 2 or 3 filter-paper disks are positioned. The cylinder is seated over the filter
-------
jv45
Q XI fy f\ iT51 *••
unit so that it rests firmly on the base. Sediment is then quickly transferred into the
cylinder through the top, followed by the teflon and rubber disks. The teflon and rubber
disks can be placed above the sample in either order to obtain a leak-free pressure transfer,
but placing the teflon disk below the rubber disk gives a cleaner seal than the reverse
order shown in Figure 5-17. The piston is depressed as far as it will go into the cylinder,
and the whole unit put in the press for squeezing. Pressure is applied gradually at first,
and when the first drop of interstitial fluid is seen the syringe is seared in its hole in the
base (effluent passage in Figure 5-1?.) The squeezed-out liquid moves the plunger of the
syringe back as the liquid is expelled, and there is minimum opportunity for evaporation.
When the desired amount of liquid has been obtained, the syringe is removed and capped.
After extraction of the liquid the parts of the apparatus are rinsed with distilled
water and (except for rubber parts) with acetone. The acetone helps dry the unit
quickly in preparation for the next sample. The squeezing and washing operations
together can be completed in 5 to 10 minutes."
-------
Pore Wate'rxExfracti'O'hN from core samples.
~ -*s
The main expenditure in this type of sampling is the
filter press. The current price of this piece of equipment
can be obtained from Baroid Division, NL Industries,
Houston, Texas. Current charges for cores obtained by wire-
line, 2-inch diameter split barrel samplers are/30 to^SO
per core. A section of core can be taken from the
sampler, molded into the filter press, the fluid extracted
and analyzed for chloride concentration, and measured for
specific conductance in a half hour or less. Therefore,
cost will" depend on the investigators' salary or hourly
billing rate.
-------
46,
Advantages
1. Inexpensive
2. Pore water extract amenable to
field chemical analysis.
3. Excellent vertical sampling if
mud invasion into core sample is
monitored, quantitative analytical
results.
4. Samples can be obtained from almost
any depth if wire line coring apparatus
is used.
5. Qualitative use of pore water extract
allows presence/absence determination.
6. Can be used with consolidated rock
as well as unconsolidated sediment
samples.
Disadvantages
1. Quantitative analysis
require careful control
during sample collect:.
2. Interstitial water can
drain from unconsolidated
sand and gravel reducing
volume of water sample
that can be obtained.
3. Disposal of dyed drilling
mud is a problem.
4. Core recovery in coarse
sand and gravel can be
difficult and time
consuming.
5. Small sample volume
available for chemical
analysis.
-------
REFERENCES CITED
1. Gill, H.E ., and others 1963. Evaluation of geologic and hydrologic data From the test drilling
program at Island Beach State Park, New Jersey. New Jersey Division of Water Policy and
Supply. Water Resources Circular 12.
f
2. Lusczynski, N.J. 1961. Filter-press method of extracting v/ater samples for chloride analysis.
U.S. Geological Survey Water Supply Paper 1544-A.
3. Manheim, F.T. 1966. A hydraulic squeezer for obtaining interstitial water from consolidated
and unconsolidated sediment. U.S. Geological Survey Professional Paper 550-C, p. C256-
C-261.
4. Swarzenski, W.V. 1959. Determination of chloride in water from core samples. American
Association of Petroleum Geologists Bulletin 43 (8): 1995-1998.
5. Walker, W.H., T.R. Peck, and W.D. Lembke 1972. Farm ground water nitrate pollution -
A case study. American Society of Civil Engineers Annual and National Environmental
Engineering Meeting October 16-22, 1972. Meeting Preprint 1842.
-------
f.tj.
O w *
D*y
Field Inspection -- £*f*' •
field inspection is an extremely valuable tool in
evaluating landfill sites. Although an inspection in the hands
of a trained observer would produce more data, even the most
unskilled person can identify the presence of leachate in
i
springs, seeps, and streams by its color and odor. Frequently,
vegetation that has been exposed to leachate can be found in a
dead or dying state. The appearance, surface configuration, and
drainage away from a landfill gives insight into the amount of
infiltration of precipitation that might be taking place. A
study of surface drainage, topography, and nearby wells enables
the inspector to make an estimate of ground-water (and leachate)
movement. Field observations increase in value when combined with
geohydrologic information and other pertinent basic data contained
in published reports and agency files.
In the following pages, it becomes evident that many of the
techniques discussed can be combined with the field inspection to
provide even more information. The degree of success is strictly
within the ability of the inspector to interpret the situation
and the amount of time available for the study.
In practice, the inspector should have in his possession at
least a sketch map of the landfill site; a detailed map or
areal photograph would be better. By walking around the pfctJL-iuiuUiJL
of—the landfill and infrrr 1 he surrounding acreage^and recording
tr*-
what is found, the overall picture is recorded to- the map, where
it is more easily interpreted.
-------
Advantages
1. Can be carried out quickly
and inexpensively.
2. Helps place the overall
problem in perspective.
3. Establishes the extent of
additional investigations
which may be required.
4. When combined with a
literature and available data
survey, can be used by an
experienced hydrologist to
roughly establish the overall
situation.
5. Provides an opportunity
for first hand discussion
with landfill operator
and other personnel.
.T- 48.
DRAFT
Disadvantages
1. Untrained inspector
may overlook subtle
but valuable data.
2. Findings are not always
conclusive in detecting
ground-water
contaminated by leachate.
3. Provides no indication of
changes in condition with
time.
4. Provides little hard data.
5. Untrained inspector may
be misled by visually
impressive Jyg «*u"t"
environmentally insignificant
features. This could occur
in either a positive or
negative direction.
-------
- 49.
r
The cost of a field inspection of a landfill can be quite variable,
depending on the size of the operation and the complexity of the
surrounding terraine. In this and each of the following sections,
an estimate of the cost of carrying out the task described is given.
This cost is based on an estimated daily rate for the personnel
required to perform the task, an estimated length of time for the
tasks based on an average situation and other related expenses such as
lab fees and living expenses. In all cases, the estimated cost should
be considered accurate only to about plus or minus fifty percent.
For a-field inspection of an average (50 acre) landfill, ,ohe man
at /'the hydrogeologist or engineer level would be required for 2X^:0
3 "days at $200. per day. '--The estimated total cost is $600.
Hughes, G.M., R.A. Landon, and R.N. Farvolden. 1971. Hydrogeology
of solid waste disposal sites in Northeastern Illinois. U.S.
Environmental Protection Agency publication No SW-12d. 154 P.
Seeps
Small springs of discolored, malodorous leachate which are frequently
found along the lower edges of many landfills are referred to as
seeps. These may be the only visible indication of landfill leachate
and, therefore, receive more than their share of attention. In
fact, however, they represent only a very small fraction of the
total leachate being generated by the landfill. The few gallons
per minute visible in seeps are insignificant when compared with
the hundreds and perhaps thousands of gallons of leachate seeping down
unseen to the water table. However, as they are indicators of
leachate, they deserve some consideration.
-------
A
Seeps may represent the intersection of the water table and
the land surface, or they may be discharge of a small perched
water body within the landfill. Sometimes a distinction
between these two situations can be made by inspection.
For example, if the land surrounding the landfill is dry,
a seep discharging along the face of the refuse is not
likely to represent the water table. A further and more
definite way of distinguishing between the two situations is
by installing a well point nearby and establishing the true
water table position near the seep. This well point has the
added advantage of permitting a sample of ground water to be
collected and tested for leachate.
One value of seeps is in the collection of concentrated
leachate samples. However, it should be kept in mind that it
is possible that the seep may not be representative of the
large volume of leachate generated in that particular landfill.
In fact, the chemical characteristics of any leachate sample,
regardless of its source, should"be considered representative
A
of the total volume of leachate. Typically, landfill leachate
has proven to be highly variable, both from location to location
in a landfill, as well as from time to time at the same point.
^ A second value of seeps is that substantial changes in seep
locations or flow rates, or the sudden appearance of new ones,
indicates a changing flow system within the landfill. The exact
nature and causes of the change, however, must be investigated
by other means.
-------
Advantages
1. Where present, definite
indication of leachate
generation.
2. Convenient point of
collection for leachate
sample.
3. Changes in flow rates
or locations of seeps
is indicative of interval
landfill changes.
£•- 51.
Disadvantages
1. May not indicate
presence of
contaminated ground
water.
2. Chemical quality not
necessarily repre-
sentative of bulk of
leachate in landfill.
-------
A
fj
Examination of seeps would typically be included as a part
of the field inspection and would not represent an additional
expense.
/V3'
5- 7 Vegetation Stress
A significant impact produced by a landfill on the surrounding
area is stress and possible destruction of vegetation. Stressed
species may include agricultural crops, stands of trees, and
marsh or meadow vegetation.
In marsh environments subject to leachate discharge, the
vegetation is an excellent eja^eetnnenESI monitor to assess
ecological stress on the total system. In addition to being
stationary and sensitive, marsh vegltation can be studied for
signs of stress using aerial remote sensing techniques as
well as directly by the botanist in the field. Crops and
trees growing in areas of deeper water table than is
associated with the marsh environment are more likely to be
stressed by landfill generated gasses than by leachate. Various
types of agricultural crops as well as fruit orchards, have been
destroyed by migrating gashes generated within a nearby landfill.
Preliminary stresses placed on these species, prior to their
actual destruction, are often detectable by the botanist and
by aerial remote sensing.
While identifying the precise cause and mechanisms of stress
may be prohibitively costly, it may be possible to relate
the stress to a general cause which may in turn be related
-------
--53.
A
to the presence of the landfill. Mapping the extent of
stressed vegetation is an excellent indication of the extent of
the total impact of a landfill on its surrounding environment.
Also, early detection of stress sometimes permits the
opportunity to institute corrective measures in time to
prevent irreparable damage.
-------
A p-
-«•
A cursory look at vegltation stress would be included in
the field inspection taks and would not represent an additional
' c
expense. A detailed survey of vegetation stress, including an
assessment of probable cause would require 1 to 2 days of field
work by a botanist plus some laboratory work. The estimated
cost of such a survey is $1,000.
If vegetation stress is to be used for monitoring, or if
specific recommendations regarding the saving or replacement
of stressed species, the required program might cost between
$10,000 and?100,000, depending on the extent, complexity and
goals of the programs.
Geraghty & Miller, Inc. 1973. Environmental Feasibility,
Proposed Silver Sands StQte Park, Milford, Conn. Project
Bi-T-55A. Report to State of Conn., Public Works Dept. Dept.
of Environmental Protection.
-------
r- ss.
Advantages
1. When found, good indicator
of contamination by
leachate or gas.
2. Mapping extent of stressed
vegetation gives good
indication of the limits
and source of contamination.
3. Stressed vegetation can be
mapped remotely i.e. aerial
photographic methods, thus
allowing wide coverage in a
short period of time.
4. Stress changes provide a
good monitoring device. This
effect may be enhanced by
actually planting selected
species in by areas and watching
the results.
Disadvantages
1. Evidence of stressed
vegetation, especially
in early stages not
always evident except
to trained botanist.
2. Some species of plants
are more resistant to
to effects of
contamination than
others. This may be
an advantage in multi-
special area as an
indicator of increasing,
or decreasing contamin-
ation or by producing a
clue as to stress
cause.
3. Stress may be caused by
many factors, some
unrelated to the presence
of the landfill.
Determination of the
responsible factor or
factors is usually
extremely difficult even
^- the botonist.
-------
r- 56.
Disadvantages, continued
4. Stress will not occur unless
physical or chemical change
occurs at the surface or within
Vide is
the vaeir zone. Therefore,
provides no indication of sub-
surface problems.
-------
.r- 57.
*»•
£•>' "Specific Conductance and Temperature Prober.
AfT* "T»
r 8
Vr;o physical characteristics of ground water v/hich can bo
readily measured in the field are specific conductance and
temperature. Since landfill leachate generally has substantially
higher temperature and specific conductance than natural fresh
ground water, the presence of leachate often can be determined
using these two characteristics.
^ Typically, in situ measurements of ground-water
characteristics would be made by lowering a remote-sensing probe
into a well and recording the results from instrumentation
on the surface. In areas of high water table, hovrever, the
measurements can be nade without installing a well. The method
involves 'the use of a self-contained conductance-temperature probe.
Construction details of such a device are shown in Figure j-~.je_
The probe can be pushed directly into the ground where
sediments are soft, or inserted into a small-diameter hand
augured hole where the ground is harder. When the probe is below
the water table, the outside tube, which has protected the
perforations from clogging during insertion, is retracted, allowing
the ground water to flow into the tube. Specific conductance and
temperature of the ground water can then be recorded. After
removal from the ground the perforated end of the probe is washed
in clean water.
Under good conditions, a two man crew can carry all
necessary equipment into the field and make a series of probe
measurements over a typical landfill site in 2 or 3 days. In addition,
measurements can be made easily in swampy -areas not accessa'olo to
drilling rigs or resistivy survey crews.
-------
t- iQ
•*"-'/.
ALUMINUM BOX FOR
MOUNTING METERS
THEMOMETER
s'r*
SPECIFIC CONDUCTANCE
METER
PROBE WIRES
HANDLE.
I INCH INSIDE DIAMETER
ALUM4NVM TUBING
WIRES
INCH INSIDE DIAMETER
ALUMINUM TUBINfr USED TO
COVER PERFORATED SECTION
CUTAWAY VIEW OF
PERFORATED SECTION *•*
SHOWING REMOTE P'ROBES
-------
"r^ r5^ A ["^i «TS»
DRA-i
-. 58.
The cost of a ground-water conductance and temperature survey
using a probe such as the one described above/ and assuming
/
the surface conditions were such that this type of survey
j
would be practical, would be about $900. This estimate is
based on the cost of a hydrogeologist or equivalent and a
helper ($60. per day) for 3 days. The survey may require a
day or two more or less depending on the size of the site to
be investigated and its accessibility.
Geraghty & Miller, Inc. 1973. Environmental Feasibility,
Proposed Silver Sands State Park, Milford, Conn.
Bi-T-55A. Report to State of Conn., Public Works Dept.
Dept. of Environmental Protection.
3. i) Electrical Earth Resistivity
An electrical earth resistivity survey can be used to define
subsurface geology and the extent of leachate contamination
of ground water. The results of a resistivity survey can
be used with a minimal amount of direct sampling as a basis
for decisions on the necessity of remedial action, or it can
be used as a preliminary investigation from which a detailed
drilling and sampling program is designed. Since resistivity
is an indirect method, however, and is subject to possible error
in interpretation, it would be unwise to base final conclusions
on resistivity results alone.
-------
r-
The earth resistivity method depends upon the conduction
of electric current through the subsurface materials.
The magnitude and distribution of the current flow is a
function of the effective resistivity (or its reciprocal,
conductivity) of the subsurface material. The effective
resistivity of saturated materials is dependent upon
moisture in interstices and pores because the vast majority
of the constituent minerals are poor-conductors. The pore
spaces that contain water also contain some dissolved salts,
and it is these ionic solutions that allow the passage of
current from the surface into the underlying material. It
has been found that the resistivity of materials such as
moist clays and silts is low; but, in dry, loose soils, sand
and gravel, or sand and gravel saturated with high-quality
water, the resistivity is high. The electrical resistivity
of a material is a function of the actual resistance of the
material, and the length of the current flow. Because earth
materials are not homogeneous, the measured resistivity is
actually termed apparent resistivity and is defined as the
weighted average of the actual resistivities of the individual
subsurface materials or strata within the depth of penetration
of the resistivity measurement.
To measure earth resistivity, a known current is introduced
into the earth through two current electrodes and the
resulting potential drop is measured between a second pair of
potential electrodes. If the electrodes are arranged in a
straight line and the separations are increased at constant /W. «><•«>•
-------
r- c.n ll\ *T> A ff» «=•
, r-so. r a EJ M a ^
£*/ S^M 3 8
it is possible to make inferences about the relations of
variations in apparent resistivity, depth of penetration, and
electrode spacing. Various procedures have been developed to
interpret resistivity data. The procedures are grouped into
two basic types: Theoretical and empirical. In using the
theoretical method, the field data are plotted, describing a
curve which is compared with sets of master curves developed
for numbers of resistivity layers with definite ratios of res-
istivity and thickness. With this method, the lvalues of
resistivity for each geologic unit as well as thicknesses and
depths can be determined. An example of an empirical
interpretation is shown on Figure s~-i?. With this method the apparent
resistivity and accumulated apparent resistivity values are plotted.
The first curve indicates the type of material and the second curve
shows the .depth of the interface between layers.
Use of the resistivity method to define a Leachate Plume relies
as the fact that the conductivity of the ground water is inversely
proportional to the resistivity measured in a section of earth
containing that ground water. Since the conductivity of landfill
leachate is generally much higher than that of natural fresh ground
water, a sharp decrease in apparent resistivity will occur where
leachate is included in the measured section. Thus, by running series
of resistivity measurements at the appropriate depth on a grid over a
landfill site, it is possible to define the lateral extent of the
leachate plume by contouring the resistivity values obtained. The
results of a resistivity survey at a landfill site are shown on
Figure _~- 2 0.
-------
aoo oo
|600 f 60
i f
H 4
1 I
M.400 R 40
20
I
N
N
\
\
v...
I
20 40 60 80
DEPTH, IN FEET BELOW LAND SURFACE
too
+ 40
WELL LOG
5
ui
w
I
u
u
u.
-20
1
ui
u
-40
-60
rafeSKfis:
•' -i *""/•
-------
AFT
NATURAL GROUND WATER ENVI3ONM
__1700
„ HIGHLY MINERALIZED GROUND WATER
ENVIRONMENT
.-' ./-^• I( Site
t
- -ft'.
-------
Advantages
1. Can define subsurface
geology and contaminated
water bodies much faster
and cheaper than drilling.
2. Can be used to greatly
reduce the number of
sampling wells required.
3. Surveys can be duplicated
periodically to provide
monitoring data.
RAFT
Disadvantages
1. Indirect method-
requires some
substantiation by
drilling.
2. Experienced operator
is usually necessary
to obtain useful data.
3. Many natural and man
made field conditions
preclude resistivity
surveys.
4. Data interpretation
in complex situation
is often questionable.
-------
jT- 62,
DIT^ A ;>»
R A fi-
The cost of a resistivity survey would be essentially the same
.as for a seismic survey ($1,800. for a typical landfill site)
and the same qualifications would apoly.
Cartwright, K., and M.R. McComas. 1968. Geophysical surveys
in the vicinity of sanitary landfills. Ground Water. 6 (5):23.
Stellar, R.L. and P. Roux. 1975. Earth resistivity surveys -
a method for defining ground-water contamination. Ground
Water. 13 (2): 145-150.
Parasnis, D.S. 1962. Principals of Applied Geophysics. John
Wiley ft Sons, New York.
Geraghty & Miller, Inc. 1973. Environmental Feasibility,
Proposed Silver Sands State Park, Milford, Conn. Porject Bi-T-55A.
Report to State of Conn., Public Works Dept. Dept. of
Environmental Protection.
,»•
£3* Seismic Surveys
Seismic surveys are used to determine the depth to bedrock and
the thickness of the materials overlying the bedrock. The
refraction method of seismic exploration utilizes the principle
that energy waves can be propagated through earth materials.
The velocity of propagation is governed by the elastic
properties of the earth materials through which the waves are
travelling. These elastic waves can be timed from their
initiation to a known distance from the energy source to
determine their velocity. With known velocities and distances,
depths to the various geologic interfaces can be calculated.
-------
- 63.
The seismic reflection method of geophysical surveying may also
be used. This system, in which the energy wave is reflected from
the different geologic horizons, can usually penetrate greater
depths than the refraction method.
Where well data are available, correlations are made between
the results of the seismic survey and existing information
for more refined interpretations. Where well information is
not available, evaluation of seismic data is based on the
interpretation of the geologic environment and experience in
geophysics.
The techniques of operation in the field depend on the various
applications of the seismic refraction method. In order to
determine depths and seismic velocities of various materials,
the reverse profile method is used. A reverse ptofile is one
in which the most distant energy source and the geophone,
which is the receiving unit, are interchanged after recording a
profile and a second profile is then recorded. The energy source
is a hammer blow on a steel plate or an explosive charge. With a
single geophone seismic unit, a- seismic profile is conducted by
implanting the geophone firmly in the ground and moving the impact
point away from the geophone at measured distances. For a multi-
geophone unit, the geophones are placed at selected distance
intervals along a line, and a single energy source, usually an
explosive device, is activated. By observing the energy arrivals
for different separations between the impact point and the receiver
or receivers, a travel-time curve can be constructed illustrating
the energy travel- time with distance.
-------
r-64. no A s»
RAF
A seismic survey requires a trained operator and an experienced
geophysicist to interpret the data. The complexity of the data
reduction process, generally requires the use of a computer.
For these reasons, seismic surveys should be contracted to a
firm providing geophysical services.
-------
Advantages
1. Can. provide subsurface
geologic information much :
faster and cheaper than
drilling.
2. Can be used to extend
geologic data over broad
areas on a limited budget.
3. Can be used in certain areas
where access for a drilling
rig would be difficult.
~- 65.
Disadvantages
A P™ "ss»
/4I- I
r. Being an indirect method,
" it requires more direct
' substantiation such as
drilling.
2. In complex geologic
formations, interpretation is
difficult and substantial
errors may occur.
3. Requires a trained person
and computer access to reduce
and interpret data.
4. Subject to noise interference
in many field situations.
-------
£-.66.
DO ,A
«* & -\
The estimated cost of a seismic survey for a typical landfill site
is $1,800, based on two days of field work for the seismic crew
and data reduction and interpretation by a geophysist. This
would be a typical survey to define subsurface geology in the area
immediately surrounding a 50 acre landfill. For surveys encompassing
**ff
substantially larger areas, the-cost would increase proportionally.
If access were difficult, if areas had to be cleared of bush for
example, the cost of this ta^s* would have to be added to the
cost of the actual survey.
Parasnis, D.S. 1962. Principals of Applied Geophysics. John
Wiley & Sons, New York.
Anon. 1972. Ground Water and Wells. Pub. by Johnson Division,
Universal Oil Products Co., St. Paul, Minn. 440 P.
Geraghty & Miller, Inc. 1973. Environmental Feasibility,
Proposed Silver Sands State Park, Milford, Conn. P,€|i/ject
Bi-T-55A. Report to State of Conn., Public Works Dept. Dept.
•
of Environmental Protection.
*A? •*. Y SURFACE WATER QUALITY. MEASUREMENTS
Surface water bodies such as ponds or streams which are in close
proximity to landfills often have an orange color and an oily
film on their surface. These obviously polluted water bodies are
discharge points for contaminated ground water which originate
within the landfill. Location of these discharge points on a
topographic map of the landfill site will often help provide
a reasonable preliminary picture of the ground-water flow patterns.
-------
r-67,
rr**s iT^j A
U K A
Where surface water bodies are large or rapidly flowing,/
dilution of leachate as it discharges is often sufficient
to prevent detection by visual inspection. In such cases,
. water samples would be taken and analyzed to establish the
presence of typical leachate constituents.
.*
Prior to the collection of surface water samples, a specific
£• W *
conductance, -Bk, Eh or dissolved oxygen survey, using portable
instruments to make in site measurements, should be conducted.
Such a survey can provide much useful information itself,
or at least indicate the locations from which surface water
samples should be taken. The importance of an analysis
of surface water quality at a landfill site is twofold; first,
determination of leachage discharge areas is important in
establishing an overall hydrologic picture, and second,
4
surface water quality degredation is an important component of
overall environmental degredation and should be carefully
examined. Also in a full investigation of surface water bodies
flear a landfill, the native biota should be studied for leachate
effects.
-------
00 .
Advantages
1. Useful in locating leachate
/
discharge points.
2. Can be a quick and inexpensive
means of estimating
environmental impact of landfill.
Disadvantages
1. Detailed analysis of water
i
samples can be fairly
expensive.
2. Surface water may be subject
to contamination from other
sources not defined.
3. Dilution may be too great
to provide useful
information.
-------
~~ 69,
IA FT
The estimated cost of a surface water quality survey as
described above, assuming significantly complex surface water
bodies exist, is $300. -This is based on 1 to 2 days work
for a field hydrologist or technician at a daily rate of $150.
It is assumed that this program would be part of a more
extensive investigation and that analysis of the results
of the surface water quality survey would be covered under a
more general data analysis phase.
Geraghty & Miller, Inc. 1973. Environmental Feasibility,
Proposed Silver Sands State Park, Milford, Conn. Project Bi-T-55A.
Report to State of Conn., Public Works Dept. Dept. of
Environmental Protection.
Landfill Gas Measurement - Landfill gasses, particularly carbon
dioxide (CO ) and methane (CH.), can present serious problems at
2 ^
landfill sites and their concentrations and movement should
always be investigated. Gas related problems include explosion
vegetation destruction, and ground-water pollution. Since
generation of carbon dioxide, methane and other gases is the
natural result of organic decomposition, all landfills will
produce these gases. The questions to be resolved are the
direction, distance, and rate of movement of the gases prior to
discharge to the atmosphere. The answers to these questions
will establish the location and design of gas venting systems
should they be necessary.
-------
A F* •".'
A
'v
At least two methods of gas measurement are available; collection of
a gas sample for laboratory analysis and in-situ measurement of the
explosive potential of confined gas. Sample collection or explosive
potential measurement of gasses in the subsurface sediment is by
specially designed gas probes, an example of which is shown in Figurer-zt.
A gas sampling bottle or measuring instrument is attached to the upper
end of the probe and evacuated. Gas from beneath the landfill then flows
through the probe to be collected or measured. Multidepth probes may be
installed as shown in Figure f-aa. In addition to landfill installations,
probes should be installed in natural sediments around the landfill to
establish the lateral migration patterns of the gasses^ All enclosed
spaces near the landfill, such as basements, manholes, etc, should be
tested for accumulation of explosive gas. Examples of a measuring device
and sampling bottle are shown in Figure S - if.
The potential for methane recovery at a major landfill should be
explored (Ref_7) The potential revenue from this resource may offset
the cost of the investigation and pollution abatement and monitoring
systems.
Problems associated with gas migration and buildup at and near a
landfill site may be alleviated by the installation of gas vents and/or
gas barriers. Typical gas vents employed in landfills are shown in
FigureS-l> Gas barriers would either be put in place prior to landfilling
where the landfill will abutta natural permeable face such as the
vertical wall of a gravel pit, or, in some cases, clay slurry trench may
be constructed after the landfill is completed if conditions indicated a
shallow barrier would be effective.
-------
-
' robe.
i*l f A*il 1 • T
PLUG END OF PROBE
CLOTH TO-BE .WRAPPED
AND TIEB AROUND X
PERFORATED END OF \
TUBING
CEMENT OR CLAY PLUS
BACK
FILLED
MATERIAL
PERFORATIONS I* MW.
(CAN USE HAND DRILL, KNIFE POINT,
OR OTHER SHARP INSTRUMENT TO
PERFORATE TUBE END)
LEAD WEIGHT TAPED OR TIED
TO BOTTOM OF PROBE
-------
-
CEMEWT OF»
CLAY PL
BACKFILL-
GAS SAMPLING TUBES
LAND SURFACE
NATURAL GROUND
OR REFUSE
GAS PROBE
-------
S -
t.-uvv^.'/""' ft-.*/'
MEASUREMENT PROCEDURE
RUBBER HOSE
PLASTIC TUBE,
METER READS EITHER
%GAS OR %LOWER
EXPLOSIVE LEVEL
CHECK VALVE
RUBBER BULB
MOISTURE
TRAP
\
COMBUSTABLE GAS
INDICATOR
GAS SAMPLING PROCEDURE
UBBER HOSE
RUBBER BULB
-v- /
-ra
-3
-------
,F
c.
e, ,.*
\
FINAL COVER
>"GAS
,6AS
:v-i\"X:-\:-:ft-'5^-V^I';::'-'l'-'^^V""-'.:>-'V:-'V^'^^^^^^^
:•••'••••;:••:•••:••'••• ••••••-• -"-••.•••.•.' •••••••••• -•^•.--
Sv^-ifSS^^S-Kv*^^^
"^:^-^^-:^v:^y^::-v. **#:-:.::'W.:'.S:..y
BOTTOM SEAL
ORIGINAL GROUND
8 DJAWETER HOUE
-------
Advantages
1. Detection of methane accumulation
can prevent explosion hazard to
personnel and property.
2. Establishes the need for special
gas ventearing system.
•*V Iv33
A!T
Disadvantages
1. Proper analysis
of gas measurement
data is complex
and would require
experienced personnel.
3. Provides a clue as to possible
cause of vegetation stress.
-------
DP ACT
I •£ f \ • •—* u
ii 'V /^^A -< n
u *>. * -A a (I
The cost of a landfill gas survey would be about $900-, including
2 or 3 days of field measurements by a hydrologist, engineer or
equivalent and laboratory analysis of several samples. Detailed
analysis of the results of the survey and remedial recommendations
are not included and the complexity of such a task and thus its
cost would depend on the results of the initial survey.
Merz, R.C. Determination of the Quantity and Quality of Gases
Produced During Refuse Decomposition. University of Southern
California, Los Angeles. Engineering Center Quarterly Reports.
U.S.C.E. Report 83-3, Sept. 30, 1962; 86-6, July 30, 1963;
87-7; Sept. 30, 1963; 89-8, Dec. 31, 1963.
Merz, R.C. and R. Stone. Gas Production in a Sanitary Landfill.
Public Works, 95:84 February, 1964.
Engineering-Science, Inc. In-situ investigation of movements of
gases produced from decomposing refuse. Final report prepared for
California State Water Quality Control Board. Pub. No. 35,
April, 1967.
"• Aerial Photography
Aerial photography has several important uses in landfill studies.
In its simplest form, an aerial photograph, whether black and white
or color, will show the landfill and drainage away from it. For
large areas, remote sensing of vegetation stress using aerial
photography map be a justifiable undertaking. Advances stress may
be visible on color photography and less advances stress may be
ennanced and distinguished using infrared photography. Another
-------
P A FT
d ^ <;-*^ sr 9
method which has been used in landfill investigations is
multispectral aerial photographs.
Multispectral photography uses special equipment to determine
subtle differences in light reflected at different wave lengths
for stressed and unstressed species. Photographic filters that
will enhance this difference are used, and several images of the
same area are made at the same time using a multi-lens camera ana
the selected filters. Differences between stressed and unstressed
vegetation are further enhanced by projecting the images through
different color filters and superimposing on a projector screen.
In addition to vegetation stress, aerial photography is frequently
useful in constructing contour and location maps of landfill sites,
Accurate contour maps of the landfill surface are used in
determining hydrologic characteristics of the landfill. Stereo
color photography is used to construct and up-date topographic
maps of the active landfill sites as the surface changes. Bench
marks, wells, and other sampling points.
-------
-- 74.
3 A C
-
~r t «
Advantages
1. Frequently can detect stressed
vegetation evidence of
contamination.
2. Can be used to prepare contour
maps relatively inexpensively.
Also provides certain geologic
information.
3. Much less costly than a
detailed ground survey of
vegetation stress.
4. Yearly photos can provide
unbiased and indesputable
evidence of surface changes;
e.g. landfill configuration,
vegetation condition, surface
water body location.
5. Can be used to precisely locate
on a map key points on the
landfill site such as wells or
^eismic Stations.
6. Enables persons to quickly grasp
the situation without visiting
the site, (other consultants,
veg, people, etc.)
*±ss~r
Disadvantages
1. Availability of aerial
photographs and
photographic services
sometimes limited.
2. Indicates little about
sub-surface conditions.
3. Indicates little as to
precise causes of detected
surface changes.
4. Requires trained interpreter
to evaluate results.
-------
F A
Aerial photographs of a landfill site nay be readily available from
a local firm or it may be necessary to have the site flown.
Available photographs generally cost about $10. to $30. and having
black and white photographs taken generally costs about $100. to
$300. Special photography, such as color infrared or multispectral
photography, with the necessary interpretation will cost up to
about $2,000. For this sum, a topographic map and a map showing
vegitation stress along with a report of the result of the photo
interpretation would be included.
Geraghty & Miller, Inc. 1973. Environmental Feasibility,
Proposed Silver Sands State Park, Milford, Conn. Project Bi-T-55A.
Report to State of Conn., Public Works Dept. Dept. of Environmental
Protection.
<,^Geophysical well logging - this method provides indirect evidence
of sub-surface formations that indicate the relative permeabilities
as well as the depths of the formations. The most common borehole
geophysical operation is electric logging. An electric log consists
of a record of the apparent resistivities of the sub-surface
formations and the spontaneous potentials generated in the borehole,
both plotted in terms of depth below the ground surface. The
measurements of apparent resistivity and spontaneous potential are
related to the electrical conductivity of the sediments, which is a
function of the size of the grains. Thus, fine-grained sediments
containing silt and clay will have a lower resistivity than clean,
coarse sand and gravel. In addition, a leachate plume may be
detectable by an electric log as illustrated schematically in Fi
-------
V- i
If ft ( it <- c f) U
,<> (,.!e r->t.r'
BOREHOLE
\
25
76
100
its
ISO
200
GAMMA
LOG
f
ELECTRIC
LOO
(RESISTIVITY)
1
1
DRILLERS
LOG
('''"-
\T
(/ «~-/xh i H. U Uvw^<-
r
U
-------
jT-76.
DRAR
Electric well logs can be run only in uncased boreholes.
Gartuna-ray logging is a borehole geophysical procedure based on
measuring the natural gamma-ray radiation from certain radioactive
elements that occur in varying amounts in sub-surface formations.
The log is a diagram showing the relative emission of gamma-rays,
measured in counts per second, plotted against depth below land
surface. Bec^cfe, soroe formations contain a higher concentration
of radioactive elements than others, formation changes with depth
can often be accurately determined. For example, clay and shale
f-iiW"*
contain more radioactive elements, such as uranium; and thorium, than
does sand or sandstone. In addition to interfaces bejtween two layers
of different materials, the relative amount of silt ^nd clay in
the formations can be determined by the inflections 6n the gamma-ray
log. Unlike electric logs, gamma-ray logs can be run in cased wells.
Geophysical well logs are used to supplement the drillers' and
geologists' logs of the materials penetrated by the borehole. An
example of the comparison between a geologic, electric and gamma-ray
logs is shown in Figure S-36. An accurate evaluation of the sub-surface
geology at a landfill site is essential to the determination of the
direction and rate of movement of leachate from the landfill and the
contaminant attenuation capacity of the materials through which the
\
leachate must move.
Geophysical well logging generally is applicable only to those
landfill investigations which include test drilling, and is
therefore not an independent tool. Gamma-ray logging can be used.
-------
RA'F'
3—^,
*"~\ UV;
DESCRIPTIVE
LOG
ELECTRIC LOS
SP
APPARENT .
RESISTIVITY
GAMMA-
RAY UDG
CASING
-WATER
TABLE
^^
-;-•*-.••*.•-*->-/
BRACKISH- -
?i^S WATER SAND
r-~Sr CLAYS-
-------
jT-77.
>RAFT
however, to gain some understanding of the sub-surface geology
at a landfill site from existing wells which may be in the
vicinity and for which no geologic logs are available.
Since geological well logging requires specialized equipment
and trained operators, the task would be preferred by a firm
offering geograp.iica4- services. In some cases, larger we'll
drilling companies are equipped to provide such services,
in which case the logging operation can be included as part of
the well drilling operation.
-------
B") A 5"1
y\ A r I
Advantages
1. Provides back-up data to
substantial drillers and
geologists log of borehole
2. Allows a more accurate
determination of depth
to formation change tha/j
may be achieved with routing
sampling.
3. Allows a geological log
c<*
to be instructed for an
existing well that was not
logged when drilled.
4. May be useful in locating
top and bottom of a
contaminated ground-water
body. Selective log
Disadvantages
1. Requires special equipment
and trained operators and
thus adds considerable expense.
-------
OP
*>~s i! *\
The cost of a geophysical well logging would be 5300 to $500 per
day depending on the complexity of the equipment and size of
the necessary crew. Normally five or six shallow wells or
two or three deep wells (several hundred feet) can be logged
in a day. Interpretation of the logs by a geoohysisif*would
cost about $400 for a typical landfill situation of six 100
to 200 foot dee? wells.
Campbell, M.D., and J.H. Lehr. 1973. Water Well Technology.
McGraw-Hill Book Co. New York. 681 P.
Anon. 1972. Ground Water and Wells. Pub. by Johnson Division,
Universal Oil Products Co., St. Paul, M inn. 440 P.
Parasnis, D.S. 1962. Principals of Applied Geophysics. John
Wiley & Sons, New York.
-------
DRA8
V/ater-Salanc5 Simplified
The wafer-balance or water-budget method is the measurement of the continuity of flow
of water for any given time interval and can be applied to any drainage basin, /tO), In this
case, the drainage basin being considered is a hypothetical landfill ead the land immediately
surrounding it. The purpose of establishing a water-balance for a landfill are -to determine the
rate of leachate generation and to establish which of the available pollution abatement proced-
ures would be most effective.
The calculation of the water-balance for a landf.ilI requires the measurement of numerous
physical parameters and can be a relatively difficult and expensive task. For most landfill
investigation and monitoring work, however, a reasonable approximation of the magnitude of
the various water-balance components will be sufficient. Methods of estimating each of these
components, using as much available information and as few field measurements as possible, are
given below.
The s^even principal water-balance components of a hypothetical landfill are shown
by arro^, on Figure/-V.These are; precipitation and irrigation, surface runoff onto the landfill,
surface runoff from the landfill, evapotranspiration, underflow, infiltration, and leachate. Also,
given on Figurej'are references to the table or figure in this section which can be used to esti-
mate the magnitude of the components and the relationships between them.
Precipitation and Irrigation
Figure £' shows average annual precipitation for various regions across the United States.
a map, however, can be considered only generally accurate. Significant variations in
Such
-------
A^-G^Cf 0)
J>
"Ti
v
C
I
-------
. . .
/N 'V.'H-i • •'<>
/'Swv "~^/-- ;>0
..<•• ii ..:-.•, i
Distribution of
Precipitation
' Xfo . £
wMVn ,A^V.AV AV- ^-^'j
na*\&
fek ({i
in j:i nvt
[BoscJ on
-------
precipitation may occur in certain localized areas, especially in mountainous regions. Sig-
nificant variations may also occur with time, an abnormally wet year for example, eSl such
abnormalities cannot be roffuUcd on a general map. For tW reason!1, it is advisable to seek
/o/"
precipitation data specfic to the landfill site and><5 the year Immediately preceeding the Inves-
^4i^^
tigatlon. Historical precipitation records for weather sfations ncard'liu landfill :itc can be ob-
>
tamed from the U. S. Department of Commerce, National Oceanic and Atmospheric Adminis-
tration, Environmental Data Service, Asheville, North Carolina. The locations of weather
staHons for which data are available are shown on maps obtainable from the above address.
Interpolation of the data from two or more stations can be made to mere closely approximate
the precipitation at the landfill site. For extended investigations or monitoring programs,
it may be desirable to determine the precise volume of precipitation reaching the landfill
surface. For this purpose, a rain gauge would be installed In a suitable location on or near
the landfill. There are nmy types of rain gauges available and the selection of one would
be based on the particular conditions of the monitoring program and atailable budget.
^
Irrigation may be used on the landfill surface to maintain a desired vegetation growth,
particularly when the landfill Is completed and its top surface is being used as a golf course
or other recreational facility. The volume of water used for irrigation should be measured
with a flow meter and added to the precipitation.
.Surface Runoff.
' ' • ^ - t
The percentage of precipitation which flows onto the landfill from adjoining higher ground
and off the landfill surface to adjoining lower ground can be calculated by the rational runoff
-------
formula described by Ven--JeChow.^(l)' A recsonable estimation of runoff can also be made
fro-i the data presented in Table 1 . ft2) where the rational runoff formula was applied to a
series of typical situations. Areas and >lopes are measured by a survey and surface conditions
are determined by inspection.
(2)
Table 1 - Percentages of Surface Runoff for a 2.5 cm Rainfall
•
Percent Surface Runoff
Sjrface Condition
Pasture or meadow
cover crop
Flat
Rolling
Hilly
No vegetation-
not compacted
Flat
Rolling
Hilly
Percent
Slope
••
0-5
5-10
10-30
—
0-5
5-10
10-30
Sandy
Loam
10
16
22
30
40
52
Clay or
Silt loam
30
36
42
50
60
72
Clay
40
55
60
•
60
70
82
EyapotranspiraMon
Evapotranspiration is the sum of water loss by evaporation and transpiration (plant water
consumption). Methods of calculating evapotranspiration are given in the hydrologic literature
(see Yen Je Chow) /(0)/ However, the large number of variables that must be measured to per-
form the calculations make ir a difficult process.
-------
DRA^T'
Estimation of evapofranspiration from available generalized da fa, such as potential
avopotranspiration maps or annual wafer consumption figures for different plant species, may
be misleading. This approach cannot account for numerous specific variables such as soil type,
;
soil water available and veg/'tafion density. Since evapotranspiration from a landfill surface
may be-anywhere from insigificant to the single most important mechanism for the removal
a.
of water from a Idnfill surface, an accurate estimate of the actual magnitude of evpofrans-
piration, from the specfic site, and at the specific time of the investigation, should be ob-
tained.
Because ot the difficulties, in arriving at an accurate figure for actual evapotrans-
pirafion, it is suggested that professional assistance be obtained. If a hydrologic consultant
is retained for the landfill study, he will be able to estimate actual evapotranspiration for
the specific case involved. IF such a consultant is not used, information on evapotranspiration
e* ' *• •'
rates for an area will often be available from a local agricultural-test station, a nearby
United States Geological Survey field office, or possibly the agriculture department of a
nearby university .
Underflow
v
Underflow is defined here as the rate of ground-water flow from adjoining areas directly
info the landfill. This condition will occur only if the base of the landfill is below the water
table. A sjecond necessary condition, however, is that the landfill adjoins or is situated near
an area of elevation substantially higher than the base of the landfill, i.e. that there is a sig-
nificant water fable gradient beneath the landfill. If the landfill is situated on level ground
-------
n-i-^
n>
-
i"~ u a
and substantial percolation of water through the landfill is occurring, leachate being generated
b/ the percolation will move away from the landfill and in directions and underflow, as defined
above, will not occur. (See Figure?')
Precise measurement of underflow, it it is occuring, it not feasible. A determination
of the occurrence of underflow, and a reasonable approximation of its rate can be made, how-
ever, by means of a relatively straightforward hydrologic investigation. Figure5'is a schematic
diagram illustrating the method for estimating the rate of underflow. This process requires the
drilling and testing of at least two wells andr4r"therefore.considerable expense will be incurred .
The drilling, however, would normally be necessary for other determinations -onywoy (e.g. water
quality)^ a*..(
Percolation
o»c
-------
-------
until almost all of the refuse has reached field capacity. For the present- discussion, if is assurm
that the landfill has reached ifs field capacity.
Calculation of the rate of percolation of precipitation and irrigation into the hypothetica
*^'2r(.
landfill is shown on Figure X. Calculation of rhe rate of leachate generation follows by adding
the value for underflow. Direct measurement of percolation is possible using a sub-surface water
3\.
trap such as the one shown in Figure 5' If infiltration is measured directly, somewhat more con-
fidence can be placed in the calculated values for leachate generation, surface runoff and
evapotranspiration .
Pollution Abatement Based on Water-Balance
Based on the results of a hydrologlc investigation of the landfill site, it may be determined
that reduction of the leachate generation rate is the best course of action, Bother possible courses
of action would include leachate removal, hydrologic barriers, physical barries, etc). In this case,
A '
the, existing parameters such as side slopes vegetation type, etc. which control the components
shown on Figure^ can be altered to increase C and D and decrease B, E, and F and consequently
decrease G . The degree of alteration required for each parameter to achieve the desired reduction
in leachate generation can be determined by calculating the effect the proposed ollu,viuliun will
have on the \oriors components of the water balance. By this means, various alternatives for
modifying the landfill can be compared and the optimal method selected.
The cost of a water balance study by a consultant, for a landfill where underflow is not a
problem would be about $1,000, including both the field and office work. In many situations,
-------
"f•„ •'[
. I I <>V\ <• I I .'>.,\ A
-------
r-
FT
T
.ACCESS FOR MEASURING WATER LEVEL
/AND PUMPING OUT BOX WHEN FULL.
CAP—^a
PI PC
' •. *"*/'. '
STEEL RODS
FIBERGLASS SCREEN
STRIP TO FASTEN
SCREEN
METAL OR
PLASTIC BOX
-------
>. n A r.*= "T7-
& ••-.
-^. i4».
the necessary field work would be accomplished during other tasks, such asfhe field inspection,
one the cost would be reduced to about $400. If underflow were a significant problem, the
*
cost of the water balance study would be closely tied to the drilling program, as multiple-
use wells would be installed and the cost spread out over seveal tasks.
A
6j Chow, Ven, 1964. Handbook of Applied Hydrology, McGraw-Hill Book Co., New York.
I
Hughes, G. M./R. A7London, and R. N. Farvolden, 1971. Hydrogeology of Solid waste
disposal sites in Northeastern Illinois. U. S. Environmental Protection Agency publication
No.SW-12d 154 p.
>. Fenn, D. G., and K. J. Han ley, 1973. Use of the water balance method for predicting
leachate from sanitary landfills. Office of the solid Waste Mangagement Program, U.S.
Environmental Protection Agency. Unpublished manuscript. 55pp.
I
-> - ' - < • r i -\. ,L ' *•-*!- "•* f - - ' s „.. * - i. •
B. • I .1 *J * . *- »• -•••••- - ri'»'-»->» - t i if * -^-f-- I u " " - —
/
• -V/S-TW
N -ML , ^ - !. U J lC P I -« I o 2 O «* «•-'
-------
GEKAOHTY 6 MILLED, IhC
-DRAFT-
Well Technology
-------
GERAGHTY ft MILLER, IMC.
DRILLING METHODS — DRAFT —
DrfVe P°?nfs - ln fh?s me'hod of d"""9, a li-or 2-inch diameter drive point is attached
to a 2-?nch pipe and driven to completion depth with a sledge hammer, drive weight,
mechanical vibrator, or pneumatic hammer. The point can be driven to approximately
30 feet by hand, and up to 100 feet if a mechanical drive weight is used, but only if driv-
ing is done in sands or finer grained sediments that offer little resistance to penetration.
Boulders cannot be overcome. Powell and others (1973) report using a mechanical vi-
brator to drive points to depths of 65 feet. Drive points, because of their small diameter,
are used In areas of high water table (near-surface) from which water can be removed by
suction pumps, for example kitchen pitcher pumps or centrifugal pumps.
Reliance on a drilling contractor to install drive points is unnecessary. Local inves- ?
Hgatlen. can drive them with a minimal investment in equipment and manpower. The first *
step Is to bore a vertical hole as deeply as possible with a hand auger slightly larger than
the well point. (Figure 17). The drive point is attached to a length of ii^p.^ foot
lengths are preferable) and placed in the augered hole. A drive cap is placed on the top
of the casing prior to driving.
Casing can be driven with a tool similar to the type used for driving steel fence posts,
or by drive weight suspended from a tripod or derrick. Drilling will be more efficient if
there is a source of power to lift the weighty they can weigW 75 to 450 Ibs. A^efl^d
i^V - '
orwcuportable-was^boring-rig-can be «sed-c^one^an be-i^ve^using a rear axle of a
auto-and tire rim for cathead. Drive points can also be driven with a sledge hammer, but
-------
Hand
driver
GLRAGHTY tt MILLEH, INC
-DRAFT —
j^ fill Simp*. to*« for dri*m* w«» P«"« «»
depth* of 15 to 30 ft.
n
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_2- GF.RACHTY a MILLER. INC.
-DRAFT-
this is difficult and slow going unless the investigator is a J
driven, it is turned slightly to keep the threaded joint tight.
-------
Advanrages
1 . Inexpensive.
2. Easily installed by hand, to limited depths,
'„
3. Closely spaced vertical samples can be .
collected during drilling. <^-
4. Can expect a good seal between casing
and formation, little or no vertical
leakage.
GEHAGMTY tt MILLER, INC
-DRAFT-
Disadvantages
1 . Difficult to develop and sample
if water table is below 15-20 ft
deep.
2. Extreme depth limitations.appli-
v cable tolhallow work primarily
\ less than 30 ft.
I
, ' N^--^« 3. No formation samples, only in-
foenation on subsurface material
penetration rate (bjflow counts, et
4. Only certain types of pumping
.. ,- ,,wr..-v can be used.
\
5. Drive point screen may become
clogged wih clay, if driven
through a clay unit.
6. Can be used only In unconsolidate
sediments'.
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GERAGHTY 8 MILLEK,INC.
-4- -DRAFT-
Augers - In auger boring, the hole is advanced by rotating and pressing a soil auger info
the soil and withdrawing and emptying the auger when it is full of soil. As much as possible,
the borehole is kept dry because water tends to prevent accumulation of soil in the auger.
? - y
Hand augering as anyone who has dug a post hole knows, can be easy or difticult depend-
ing on whether or not clay and sand or gravel, respectively is being, removed. Small
diameter helical or posthole augers can be used to advance 2 to 12-inch diameter holes
by hand to depths of 20 to 30 feet (Figure 18). If a tripod and pulley are set up to aid
in pulling the auger from the hole, depths of 80 feet can be reached. If the hole can be
kept open below the water table, usually only in cohesive material, a screen and casing
can be set, backfilledjand developed.
This process becomes much simpler and less time consuming if power augers are used.
Here, flights of spiral of hollow-stem augers are forced into the ground while being rotated,
and the spiral action of the augers conducts cuttings to the surface (Figure 18). On comp-
letion of drilling, a small diameter casing and well point are pushed to the desired depth.
With bucket augers, a large-diameter barrel fitted with cutting blades, (up to 48 inches
in diameter) is rotated into the ground until it is full. The earth-laden bucket is fhen
brought to the surface, pulled to one side, and dumped. This process is repeated to
completion depth. Bucket augers would not normally be used in landfill investigations,
and they are not evaluated below.
Power auger^can be tied very effectively in cohesive soils. On the other hand, these /
augers are not well suited for use in very hard or cemented soils, and they often fail to
retain very soft soils and fully saturated cohesionless soils. However, if setting a drive point
is the ma in purpose of the hole, slups or cave-in of the hole in cohesionless sediment is
A
not a major drawback.
-------
n MII.I.EI:, ir,
D R A F T -
I
i
I
.
s
SMALL HELICAL AUGER POSTHQLE OR IWAN AUGER
V\V. :-..
I
i — A £A3TH DqiL'- WITH CONTINUOUS HELiCAL A'JGEP
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Advantages
1 . Inexpensive.
2. Small, high-mobility rigs can get to
most sites.
3. Can be used to quickly construct
shallow well clusters.
4. If borehole reaches refusal depth too
soon, set up time is low and rig can
be moved rapidly.
5. No drilling fluids introduced into
the borehole, no possibility of
diluting formation water.
GERAGHTY 8 MILLER, IMC
-DRAFT-
4.
5.
Limited penetration, normally
100 feet, max. 150 feet.
Vertical leakage through sedi-
ment left in borehole, through
which drive point is forced to
completion depth. No way
to isolated screened zones of
aquifer.
Careful attention during drilling
is required to get a correct log
of formation materials penetrated.
Unable to collect ground water
samples during drilling.
Core sampling is possible^,only
if hollow stems augers flights are
used.
Can be used only in unconsolidate
sediments.
Borehole will collapse in cohesion
less sediment.
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-6- GErtAOHTY a MII.LEP, INC
-DRAFT —
Wash Borfng - A waih boring is advanced partly by a chopping ana rwisring acnon or a cnisei-
shaped bit and partly by the jetting action of a stream of water pumped through the drill rod
and out the bit^ (Figure 19). As the bit penetrates the formations, the casing sir.ks of its own
C-VT.VM;
accord due to the washing action of the bit alone. Currirtgs are carried to the surface by
the water circulating in the cnrjlar space between the drill pipe and casing. The drill
string is lifted and dropped to get a cutting action with the bit at the same time it is rotated
to make the bit cut a round hole. These operations, as well as the pumping, may be performed
jj
entirely by hand, but a small ^motor-driven winch and pump are generally used. A closed
system is used to recirculate the drilling water. Water is pumped from a pit into the drill
string and out of the bit. This water, after it circulates from bottom to top of the borehole,
is conducted back to the pit where the cuttings settle out. Normally, small pits are used to
reduce the volume of water required. As a result, cuttings have to be cleaned out of the
pit at regular intervals.
The drill rod Is generally 1 to 2-inch black iron pipe. Casing is required to keep the
hole open in soft clays or sand and gravel, but is often not necessary in stiff clays or similar
cohesive sediments. If the borehole stays open by itself, casing and screen are simply lowered
and backfilled to construct a well . If casing is required to drill, slip screens are set by the
casing pull-back method.
Drilling-equipment is simple/and-readily-available to-loccrl investigatorr'who'wishisSr-t'O"
doJJieir.own-botings. The basic units are a tripod, a pump, and a cathead. The only comp-
onents that need to be purchased from a drilling rig company are the water swivel and the drill
bits, although the bits can be easily fabricated in a metal-working shop.
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GERAGHTY a MIL'-ER, IMC
-DRAFT-
Fifr^g^VV A 5bt-B€>«4NO
-------
7
Advantages
CtKAMITY L\ MILLE.-',
-DRAFT-
Disadvantages
1.
2.
3.
4.
Inexpensive and light1 equipmenh.grill-
ing contractor not required. ~
Excellent for shallow bore holes in un-
consolldated sediments.
Can get vertically spaced ground-water f
samples if drive point is forced ahead of
borehole and pumped. ^
Drilling equipment can get to almost any
site.
5. Core samples can be collected.
1.
2.
4.
5.
6.
7.
8.
Slow, especially at cleprh .
Maximum depth of 100 to 150 feel
Cannot penetrate boulders and
wash up gravel.
Difficult to develop and sample
if water table is deeper than
15 to 20 feet.
Can be used only in unconsolidate
sediment.
Wash water can dilute formation v
must be taken into account in
vertical sampling.
Interpration of geology from wash
samples requires skill.
Can set only short sections of
screen without difficulty.
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GERAGHTr 8 MILLEK, l.'iC
-DRAFT-
Jet Percussion - The drill fools and the drilling action of the fet-percussion method are the
same as those described for wash boring, however, casing is driven d'uTing drillTrig with a
drive weight'.and not allowed to advance of its own weight. Normally, this method is
used to place 2-inch diameter casing in shallow, unconsolidated sand formations, but has been
•t"
used to install 3 * 4-inch diameter casings to 200 feet. Screens have to be set by the casing
pull back method.
Most jet-percussion rigs are moderate-sized pieces of equipment and drilling contractors
used to working in unconsolidated sediments will probably be the best source of a rig.
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GERAGHTY a MILLED, INC
-DRAFT —
Cohhead
Air Chamber
••
Pump |
/Sucrion Hose
Settling Tank
Drill Rod
High Pressure
Drive Shoe
Cross-Chopping Bit
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GERAGHTY & MILLER, 1,'iC
-DRAFT-
Advantages
Disadvantages
1 . Inexpensive.
2. Simple equipment and operation.
3. Good seal between casing and formation
prevents vertical leakage of formation
water.
4. Can obtain a reliable formation water
sample at completed depth.
1.
2.
3.
4.
5.
6.
7.
Slow.
Use of water during drilling
can dilute formation water.
No formation water samples
can be taken during drilling.
Poor soil samples because fines
are washed out of sample.
Small diameter (2in.) and shallo
maximum depth (125 ft.) limits
usefulness of this type of well to
water sampling at shallow depths
Large number of wells requirec.
at one location to obtain closely
spaced samples throughout the
contaminated thickness of the
aquifer.
i
5 •'.^; !
Can^e used on unconsolidated
sediments or weathered rock.
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-10-
GERAOHTY tt MILuEH, IN'!
-DRAFT —
Cable-Tool Percussion - In cable-tool percussion drilling, I
regularly lifHng bnd dropping a heavy string of drilling tools in the borehole (Figure 21).
The drill bit breaks or crushes hard rock into small fragments and in soft, unconsolidated
sediments, loosens the material. The up and down action of the drill string mixes the
crushed or loosened particles with water to form a slurry or sludge. If no water is present
in the formation being penetrated, the necessary water to form the slurry is put into the
borehole. Cuttings are allowed to accumulate until they start to lessen the impact of
the bit, and then are removed with a bailer or sand pump.
A cable-tool drill string consists of four units: the drill bit, drill stem, drilling jars
and rope socket. The bit provides the cutting edge of the drill string, the action of which
e
is jinhanced by the weight of the drill stem. This weight also acts as a stabilize^keeping
the hole straight. The jars are a pair of sliding, linked bars which provide a play\in the
drill string .of 6 to 9 inches. If the tools become stuck, the jars permit successive upward
blows in the attempt to free them rather than a steady pull on a cable which might part.
The shaking and vibrations produced by the jars helps in freeing a stuck drill string. The
rope socket connects the string of tools to the cable and allows the tools to rotate slightly
with respect to the cable.
The bailer consists of a section of pipe with a check valve at the bottom, and is filled
by an up and down motion in the bottom of the hole. Each time the bailer is d/ipped, the
valve opens, allowing the cuttings slurry to move into it. The up and down motion ?s con-
"
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GERAGHTY a MILLER, INC.
-DRAFT-
-------
OKI'ACHTY iA Mil '.Ef<, \t>(.
~n~ -DRAFT —
tinued until the boilei is full. At this point, it is brought to the surface and the contents
clumped on the ground. The sand pump is a bailer that is fitted with a plunger so that an
upward pull on the plunger tends to produce a vacuum that opens the valve and sucks sand
or slurried cuttings into the tubing.
c
Casing is driven by attaching a drive clamp to the drill stem and the reciprocal action
A i1 <• K?w A f
of the rig hammers the casing into the ground as the clamp makes contact with the top of the
A
casing. Operation can be speeded up by drilling ahead of the casing, but only if the hole
will stay open by itself. If drilling open hole and there is a cave in, the drill string could
be tapped. Cautious drillers}therefore, rarely drill ahead of the casing unless they are
going through rock. Normal^ procedure in unconsolidated sediments is to drive fhe casing
into the formation and then clean out inside the casing with the drill tools. This is slower
but safer than drilling ahead of the hole.
-------
Advantages
GERAGHTY ft MILLER, INC.
-DRAFT-
Disadvantages
'„•._ . Inexpensjye>-Tf non union drillers-'dre
inu&rved. ~~~ ""
Simpl-3 equipment and operaHon.
Good seal between casing and formation
if flush joint, casing is used.
Good disturbed soil samples, know depth
from which cuttings are bailed.
Core samples can be collected.
If casing can be bailed dr/i w/jfhout
sand heaves, a formation water sample
at that depth can be collected.
Can be used in unconsolidated sediments
and consolidated rocks.
Only small amounts of water are required
for drilling.
3.
Ov r^L. ^j^f ,
'lu 5^.—-,
J.
1. Slow.
2. Use of water during drilling can
dilute formation water.
3. Potential difficulty in pulling
casing in order to set screen.
4. No formation wet er samples can
be taken during drilling unless
open-ended casing is pumped.
5. Heavy steel drive pipe -s used
and could be subject to corrosion
under adverse contaminant char-
acteristics.
6. Cannot run a complete suite of ge
physical well logs because of stee
casing.
-------
II
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'.''OM — JC.^ f°*T=T
Sffl?^1
IP
ff-S^.1—,
- ROTARY DRILLING , '
/
TWO-CONE BIT
L>ras-t\pe hits >*i«h rrplnceaN
-------
-13- GE.KACHTY a MILLEP, IMC
-DRAFT-
Hydraulic Rotary - To drill a hole by the hydraulic rotary method, a roraring oir oreaKb
up the formation and the cuttings are brought to the suiface by a recirculating drilling
fluid (Figure 22). Drilling mud is pumped from a settling basin, through a water swivel,
and down the hollow interior of the drill rod. At the bit, nozzles direct the fluid to
efficiently clean cuttings from around the bit and it then flows upward in the annulus,
carrying the cuttings to the surface. Here, the fluid is discharged into the mud pit and
the cuttings settle out. At the other end of the pit, the water is sucked into the pump
to circulate down the drill rod again.
Teh' drill string consists of the bit, a stabilizer, and the drill pipe. Two basjrf
c f
types of bits are used: roller bit in rock and -consol i doted sediments and drag bi£ in un-
consolidated materials. Roller bits have conical rollers with hardened steel teeth of
various lengths, $ spacing and number dependent on the type of material to be drilled.
Some rollers have inset carbide buttons for drilling in hard, tough rock. As the rollers
rotate, they crush and chip the formation material. Drag bits have fixed blades, the cut-
ting edge of which is surfaced with carbide or some other abrasion-resistent material.
DfiiUn^actionTs-the-resull- otthese-bJades -scraping material off the- borehole- wall .
Tl
The bit is attached to a heavy, weighted section of the drill string called a drill
collar or stabilizer. This weight just abov~the bit tends to keep the borehole straight
and vertical . The drill rod connects the stabilizer to the kelly be* and and ranges in
•\i • »- • £ OT ."'-''"-
outside ebember from 2 3/8fto 4-inches. The kelly is a fluted bar which passes through
f. f A
a rotary table, which imparts a rotary motion to the drill string. When- the.iength of the
..•
y^ has been drilled, a new section of rod is added and drilling is started again.
-------
Advantages
Cti-iA'JHTY i\ MILI-CI!, IN'
-DRAFT-
1 . Fast .
2. Dilution of formation wafer Is limited
by formation on a filter cake on bore-
hole walls.
3. Formation water sample can be obtained
with a special technique.
4. Good disturbed soil samples from known
depths if travel time of cuttings up bore-
hole is taken into account.
5. Flexibility in final well construction,
such as screen placement.
6. Can run a complete suite of geophysical
well logs.
7. Core samples can be collected.
1 . Expensive.
2. Complex equipment and operatioc
3. Potential of vertical movement
of water in formation stabilizer
material placed between casing
and borehole wall after comple-
tion.
8. Can be used in unconsolidated sediments
and consolidated rocks.
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GERAGHTY 8 MILLER, INC.
-15' -DRAFT —
Air Rotary - As in hydraulic rotary drilling, a rotating down-hole hammer is used to break
up formation material by percussion, but rather fhan a liquid carrying cuttings to the surface,
high velocity compressed air is used. Down-hole hammers are essentially pneumatic hammers
similar in operation to those seen being used to cut up pavement by road repair crews. Nor-
mally this type of drilling equipment is used in rock because of fantastic penetration rates
compared to cable tool or mud rotary drilling; drilling rates of one to two feet per minute
are not unusual. Unfortunately, down-hole hammers larger than 6 inches are not readily
available, limiting the size of the borehole that can be drilled. Much of their speed ad-
vantage is lost when conventional roller cone bits are used. However, drilling water is
not required, eliminating a logistics problem that can become difficult especially in arid
regions. Most rigs are equipped with a small mud pump so they can drill a conventional
rotary hole through unconsolidated overburden on top of the rocks. When the hole is fin-
ished, casing is set_sjg_wgr.to rock to prevent caving.
Advantages Disadvantages
Same as discussed in hydraulic rotary drilling
A minimum upward air velocity of 3000 feet/minute is required to lift cuttings to the
surface. When drilling a four inch diameter hole with 2-3/8 inch rod at least 150 cubic
feet/minute (CFM) of air are required to lift cuttings. If a prolific aquifer is penetrated,
!.£._,
the hammer may be "drowned out", -re^the compressed air cannot lift the volume of water
entering the hole to the surface. At 3000 ft/sec air velocity, this threshold is met at about
50 gpm in a 4 inch hole, and at about 150 gpm in a six inch hole. When this happens, a
-------
GtUAOHTY -i MIL.LEI', IN'.
"16~ -DRAFT--
i
v..- .-..-«
larger air compressor is required or drilling must »w4teh to the hydraulic rotary method. Air
rotary rigs are available with compressors capable of supplying 1100 CFM at a pressure of
250 psi.
Well Casing & Screen Materials
Landfill leachate can be characterized as a stron e.'ectolyte which may be corrosive.
Specific characteristics of the leachate will depend on the type of material accepted by
the operators. Therefore, some thought must be given to the materials used in monitoring
well construction in order to prolong the installation's operating life to at least match
that of the landfill. This is not an adequate design criteria.however, the monitoring well
should be serviceable for as long as required after the landfill is completed. Review of
\
comoarison tables of various pipe materials to chemical attack (Robintech, Inc.T indicates '•-..-.
t
that PVC pipe is resistant to most chemicals, with the exception of ketones, esttfers, and
aromatics (amonf the more common chemicals), when compared to the other normally-used
well casing, steel pipe, PVC casing (p*p») is a nonconductor and will not be involved in
electrochemical reactions as we4J, for example, a steel casing and brassjf or iron well screen.
Nor will it normally interact with the leachate as will steel casing.
From a leachate sampling standpoint, PVC is very attractive. Because of its chemical
inertness, it will contribute little in the way of chemical constituents to a leachate sample ex-
. -|x i •
cept in the parts per billion range. Steel pipe can be expected to contribute at least-ion, and
probably other ions to a sample. Of course, this sample contamination can possibly be avoided
by proper flushing of the well before collecting a sample in both steel and PVC casing.
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GERAOHTY 8 MILLER, INC.
-DRAFT-
A major drawback to PVC casing is its lack of strength. Landfill equipment or vandals
can easily snap off a PVC casing projecting above ground surface. Therefore, special well
protection measures (described in the Well Security section) must be taken. In spite of all
this, PVC casing and screens appear to be the best materials to use in constructing landfill
monitoring wells.
Actual well construction, however, will be dictated by a variety of constraints, such
as drilling method, aquifer type and formation materials, cost of well consrruction materials,
•-^' I
east of installation, and personal prejudices, among others. Proper construction materials
^
can be best evaluated for each situation by a person familiar with landfill investigations,
but a person not familiar^ can fall back on a drilling method that will allow PVC casing
^ ' .
and screen to be installed and be confident that the well will last and not bias the samples.
Well Security
Once a well has been completed, some measures must be taken to protect the installation
from: 1) normal landfill operations, especially heavy equipment and, 2) vandals. In areas
being actively landfilled, provisions have to be made for extending the well casing and its
protection above the active level of the fill. An installation capable of protecting the
monitoring well and being added as the depth of the fill increases is shown in Figure 23.
Construction of this protective installation is straightforward and inexpensive with a reason-
able likelihood of remaining undamaged by landfill equipment on vandals. To do this, a 10-
foot length of steel casing several inches larger in diameter than the monitoring well is placed
-------
GERARHTY a MILLEff, In'.
-DRAFT-
over it. This casing is grouted in place with a cement collar at least four or five feet deep
to hold it firmly in position. Although this will net withstand a run-in with a compactor or
bulldozer, it will withstand attempted vandalism. The casing should be threaded so that a
screw cap can be used to close the well. Two heavy duty, hardened steel hasps welded on
opposite sides of the cap and casing will allow the well to be locked. As long as heavy duty
hardened steel hasps and padlocks (capable of withstanding a 48-inch bolt cutter) are used,
the efforts of even the most determined vandals will be in vain. If this type of installation
is broken into, it will be for thopurpooo O6 sabotage, not simple vandalism.
Unless this well is highly visible, chances of it being struck by equipment during normal
landfill operations are fairly high. To avoid this, a sample tripod constructed of timbers
(railroad ties or equivalent) should be constructed over the well and crowned with a bright-
ly colored object, such as a flat or painted tire (Figure 23).
When landfilling threatens to overtop the installation, the tripod is temporarily knocked
down, additional casing added to the monitoring well and protective shell, and placement
of trash and cover is continued around the well. If this procedure is followed, only a slight
interruption in the normal course of landfill operation will be required to protect the mon-
itoring well for future sampling.
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-19-
Woter Withdrawal Methods
Water can be withdrawn from wells by a variety of methods including: bailers, thief
samplers, pumps, or compressed air. Theprimary consideration in collecting a sample is
insuring that a_l]_ stagnant (standing) water has been removed from the well casing before a
sample is collected. On cessation of pumping, water standing in a well begins to stratify,
with water in the screen mixing with formation due to normal ground-water flow, and
A
water above the screen becoming more and more isolated because there will be little or
no vertical mixing with the water in the screen. Improper well construction can cause all
the water in the casing to be stagnant because of vertical leakage of leachate down along
the well casing to the screened zone, or vandals dropping material into the well. There-
fore, to obtain ground-water samples representative of chemical quality In the aquifer at "
the time of sampling, at least one volume of water standing in the casing and discharge
pipe must be removed before sampling.
However, removing one volume is no guarantee that the stagnant water has been flushed
from the well - four or five volumes are required tcrteronTt/feSofeTide;- If this seems like
•^- <-:.£.'>".r>
0"ho*=of effort-just to-get a water sample, consider the expense of chemical analyses and
the possibility of having to repeat an analysis because stagnant water was sampled. Re-
member that the stagnant water may contain material introduced from the surface, inadvert-
rl. - l)
- -f't-tf^r- -.t •
ently or deliberately, which would result in analytical results eiavatcd-beyond-ochjol aquifer
water quality. This might ultimately result in adverse actions by an enforcement agency,
,ajl because of an improperly collected sample.
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GLKAGHTY a MILLEH, IMC.
-DRAFT-
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-------
-------
-
M a ^ >-A J
In light of this discussion, bailing by hand is not a recommended well sampling method
unless adequate precautions are takun. Bailing is accomplished in small diameter wells by
lowering and raising a weighted bottle or capped length of pipe on a length of rope. Rarely
can a sufficient quantity of water be removed to adequately eliminate stagnant water from
• "*"" f
the sample, unless innumerable, time consuming trips in and out with the toiler are made.
Often, people sampling a well will use the first bailer full of water as the sample because
e,
of the easf with which the sample can be collected. The reliability of this sample is nil
ond thi£ fact must be impressed on the sample collector. Of course^ in situations where
the well can be bailed dry or there is only several feet of water in the bottom of a shallow
well, representative samples can be obtained with a bailer because the casing can readily
be emptied.
Where the water-table is within suction lift, small-diameter wells can be sampled
with centrifugal, peristaltic or pitcher pumps. Peristaltic pumps have rather low pumping
capacities but are attractive because the sample Is conducted throug inert silicone rubber
tubing, reducing the possibility of sample contamination by constituents from the sampling
apparatus. Small, highly portable centrifugal pumps are available with pumping rates from
5 to 40 gpm, and removing stagnant water and flushing the discharge set-up clean will pose
little difficulty, allowing collection of representative samples. If concentrations of less than
1 ppm are being investigated, extra care mast be taken in sampling, ond in the extreme ppb
range, the peristaltic pump would have to be used.
-------
Pitcher pumps can be easily carried to a site, screwed onto a well, and used to purrp
a sample. No power source is required other than the investigato^ana^^costs are low,
'• 1
As an alternative to these pumps, an inexpensive bailer pump can be constructed from read-
ily available materials (Leonard, ). This pump consists of a length of garden hose with "
a foot valve at its bottom end and fittings at its top end that allow a vacuum to be applied
to the hose. A water sample is collected.by moving the hose up and down, activating
the foot valve, and the partial vacuum assists in bringing water to the surface. Vacuum is ob-
tained from an automobile engine. Keep in mind, however, that this sampler should be used
where the well contains only a small volume of ^ter'^^dearfng stagnant water &X%f
the casing does not become an inordinately time consuming process.
An inexpensive air lift sampler can be constructed from polyethylene or any reasonably
flexible tubing as shown in Figure 24. Because the tubing is flexible, it can be readily
coiled and moved conveniently from well to well. Primary limitations on the sampler are
the amount of air pressure that can be safely applied to the tubing and a source of compressed
air. A high-pressure hand pump ^ serve nicely fo/lhallow water table buttmall air
A '• j A
compressor may be required for lift greater than 30 feet. The advantage of this sample is
that it can be -^ftro fit the monitoring well -vafivices-o^s7not^?'37TTnc1r
-------
'P • "• ;;- 7
IL-*' (JM^-i j* 3
Somewhat more elaborate pumping equipment is required in small-diameter wells
where water level is below suction lift. The easiest, but not the driest, way to collect
A . j^Mi
a sample is topiOESh airline dSton the well and blow the water out. However, trying to
adjust airflow soi that water flows smoothly over the top of the casing instead of blowing
violently into the air is a difficult task. Addition of some simple, relatively inexpensive
hardware to cap the well can make sampling a straightforward and easy process. Sommerfelt
and Campbell (1975) have described such an installation (Figure 25) and Trescott and Finder
(1970) have pumped water from as deep as 190 feet withyjFype of Installotion » Air pressure
W.y»flO/><.Jl _ '
can-eemerrom a sflg^tt'gasoline powered air compressor, an engine air pump, or a compressed
air cylinder. The source of air pressure selected will depend on well site accessibility
and budgetary constraints. If a well can only be reached on foot, low-volume, high -
pressure hand pumps (available in stores handling racing bicycles) can be used to supply
/" \ye>>lv;v^«-NT'^^vr ~tU«'.. |n:-£V' r<2-j \f \
ir pressure of up to 160 psi. [ II i i L -\ -f" J
V O f
-------
,.^- Sc ^
OQ A L
K A
4 -*r Vj •••—t
Fig.4 SchMTMtic diagram showing th* construction and
mechanism of ttw pump.
-------
REFERENCES CITED
1. Anonymous 1972. Ground water and wells. U.O.P. Johnson Division, St. Paul, Minnesota.
2. Hvorsley, M. Juul 1965. Subsurface exploration and sampling of soils for civil engineering
purposes. Engineering Foundation, New.York, NY 521 p.
3. Matlock, W.G. 1970. Small diameter wells drilled by jet-percussion method. Ground Water
8 (l):6-9.
-------
Htfss0*' IS B ffi A{| n jo. \i IA 'XV&&1 t> .'I
E L I Ivi I I\J A w V
_ &i»wl!¥lli is/nt % I
CHAPTER 6
INDICATORS OF LEACHATE
6.1 I1ITRODUCTION
As can be seen from the composition data presented in Chapter 3, leachate
represents an extremely complex system containing soluble, insoluble, organic,
inorganic, ionic, nonionic and bacteriological constituents in an aqueous
medium. Figure 6-1 schematically depicts an extensive characterization of
leachate by means of physical, inorganic, bacteriological, and organic
parameters.
In setting up a monitoring program, one must consider all the factors
affecting the quality of the pure leachate and "leachate-enriched ground
water" and the resultant environmental impact including:
. purpose for monitoring
. background quality of ground water at the site
. other sources of ground-water pollution
. hydrologic renditions of the site and the resultant
monitoring network being utilized
. climatologic influences
. costs and availability of manpower and laboratory
facilities
. site history
A major item in any monitoring system will be the costs for the analytical
measurements. There are several ways these costs may be minimized, yet
6-1
-------
meet regulatory requirements, the most important being proper selection
of indicator parameters to be monitored.
It will be the function of the regulatory agency to specify monitoring
requirements for land disposal sites. Some of the necessary analyses
will be time-consuming and relatively expensive. The regulatory agencies
should maintain flexibility to consider approval for substitution of a
less expensive analytical indicator if the paramenter requiring the more
expensive anslysis can be accurately inferred from the simpler, less
expensive analytical indicator. An example of this would be the substi-
tution of COD (Chemical Oxygen Demand) analyses for a portion of the BOD5
(5-day Biochemical Oxygen Demand) analyses if it can be shown that a
satisfactory correlation exists between the two parameters. Monitoring
land disposal sites can also be looked at in the quality control sense.
Here, a regulatory agency can allow, at least for the frequent monitoring,
the selection of indicators be subject only to the requirement that Ouf£oa.|
control &**y»*m»»''iaetuXAwground-water quality -av\«t permit specifications]^tn
It is here that a strong effort should be made to utilize inexpensive
indicator analyses which can provide quick, accurate and correct information
of those indicators requiring more expensive analytical techniques. Prompt-
ness of analysis is quite important since having the results for early
action will greatly simplify control requirements and sample degradability
effects will be minimized. As an example, conductivity can sometimes be
used as an indication of total dissolved solids. This is a simple measure-
ment, and one which gives immediate results. It is absolutely necessary,
however, to obtain a correlation between the two indicator analyses for
the particular land disposal site being monitored.
6-2
-------
5CtfB4ATiOVDTA'GRAM QF
72JTIQM
SPECIFIC-
COK&UCTANCSl
W
1 I
r
I
AMMO A//A
1C
cguea&L ANALYSES
BACTERIOLOGICAL
C.OLIR>RM:
STD
P
c
ox
01 u
TOT-1.L-
6>oD,
MSAS
SuLFATE:
N I
i *. L_
«] I o-V*»
-------
This chapter will provide guidelines for selecting indicators as well as
scheduling and data management and interpretation resulting in a repre-
sentative, valid and cost/effective monitoring program. The emphasis of
this chapter is on passive monitoring which Chapter 4 defined as the
sampling of monitoring devices, strategically located in reference to
ground-water flow directions, at regular intervals to determine chemical
constituents in the ground water at that point and time. In addition,
this chapter assumes that the landfill being monitored includes only
4
normal municipal solid waste. Where special wastes are involved, such
as hazardous chemical and liquid wastes, the indicator selection and
sample scheduling would be modified accordingly, to be more waste specific.
The presentation in this chapter will be keyed into the fundamentals of
leachate and the monitoring networks that were presented in Chapter 3
and 4, respectively.
6.2 BACKGROUND QUALITY OF THE GROUND WATER
The background water quality at a land disposal site must be considered in
selecting the indicators for a monitoring program. For example, a ground
water with a high background iron content would certainly lessen the
value of iron as a leachate indicator, because it will require higher
concentrations of iron to differentiate from background. In a given land-
fill situation, it is necessary to obtain adequate background data in order
to draw reliable conclusions regarding possible leachate contamination.
Therefore, consideration must be given to both the ground-water quality
which occurs in nature, as well as other possible sources of contamina-
tion which may affect the background quality.
6-4
-------
Reliable data on background quality of ground water can be of critical
importance relative to regulatory and legal considerations.
6.2.1 CHEMICAL QUALITY OF NATURAL GROUND WATER
All ground water contains chemical constituents in solution. The kinds
and amounts of constituents depend upon the geologic environment, movement,
and source of the ground water. Typically, concentrations of dissolved
constituents in ground water exceed those in surface waters. This is
particularly true in arid regions where recharge rates are low.
Dissolved constituents are primarily derived from minerals in contact with
ground water and percolating water going to ground-water recharge. Common
chemical constituents of ground water include:
Cations Anions Undissociated
Calcium Carbonate Silica
Magnesium Bicarbonate
Sodium Sulfate
Potassium Chloride
Nitrate
Table 6-1 lists relative abundances of these and other chemical constituents
in natural ground water. Minor and trace constituents are present selectively
depending upon the mineralogy of the region. Analyses of ground water
samples enriched in silica, iron, calcium, and sodium are given in Table
6-2. These elements are frequently enriched in ground water. Brines and
thermal spring waters were not included in Table 6-2.
6-5
-------
si. A
TABLE 6-1
RELATIVE ABUNDANCE OF DISSOLVED SOLIDS IN
PORTABLE HATER'*'
Major Constituents (1.0 to 1000 ppra)
S Bicarbonate
Calcium
Magnesium
Silica
Sulfate
Chloride
,.
Secondary Constituents (0.01 to 10.0 ppm)
Jron . , .. Carbonate
Strontium Nitrate
Potassium Fluoride
Boron
Minor Constituents (0
Antimony
Aluminum
Arsenic
Barium
Bromide
Cadmium
Chromium
Cobalt
Copper
Germanium
Iodide
001 to 0.1 ppm)
Lead
Lithium
Manganese
Molybdenum
Nickel
Phosphate
Rubidium
Selenium
Titanium
Uranium
Vanadium
Zinc
Trace Constituents (generally less than 0.0001 ppm)
Beryllium r
Bismuth ,
( ) Silver
Cesium Thallium
Gallium Thorium
Gold Tin
Indium Tungsten
Lanthanum '
Platinum Zirconium
6-6
-------
Ground-water quality Is classified according to domestic and industrial
use on a simplified basis for convenience. Salinity, the concentration
of total dissolved solids, and hardness, the combined calcium and magnesium
concentrations, are classificatory criteria. The classification scheme
is shown on Table 6-3. Water with a high concentration of dissolved solids
can build up scale in boilers, be harmful to plants when used for irrigation,
and interfere with quality of products in manufacturing. Hard water also
builds up scale deposits in boilers, and forms scums with soap in laundering.
Within a large body of ground water, the natural chemical composition tends
to be relatively consistent. Variation of ground water with time is minor
in comparison with surface-water quality changes.
Ground water under natural conditions tends to increase in salinity with
depth. Most of the geologic formations in the United States are underlain
by brackish to highly saline waters. Density and permeability differences
act to maintain a separation between these waters and the overlying fresh
ground water. (
6.2.2 OTHER SOURCES OF GROUND-WATER CONTAMINATION
It should be evident from this discussion that ground-water composition can
vary widely under natural conditions. Man's activities add another dimension
to the complexity of ground-water quality. The effect on ground-water
quality of point sources of contamination such as waste lagoons, acid mine
spoils, and oil well brines are relatively easy to trace. Diffuse sources
of contamination such as regions of septic tanks, irrigation, or farm
chemical usage may affect bodies of ground water creating a chemical enrich-
ment which is relatively uniform. Detection of point-source contamination
6-7
-------
RAFT
Table 6-2 ANALYSES OF GROUND WATER IN WH.'CH THE INDICATED
ELEMENT IS A MAJOR CONSTITUENT. C&NCENTRATIONS
INMG/L UNLESS NOTED,
Constituent
Silica
Iron
Calcium
Sodium
Silica (SI02)
Aluminum (Al)
Iron (Fe).
Calcium (Ca)
Magnesium (Mg)
Sodium (Na)
Potassium (K)
Carbonate (CO3)
Bicarbonate (HCO3>
Sulfate (SOJ
Chloride (CI)
Fluoride (F)
Nitrate (NOa)
Dissolved solids
Calculated
Residue
Hardness as CaCO3
Noncarbonate
Specific condustance
umhos/cm @25
pH units
Temperature, °.C
99
—
0.04
2.4
1.4
100
2.9
24
111
30
10
22
0.5
348
--
12
0
449
9.2
50.0
20
'• —
2.3
126
43
13
2.1
—
440
139-
8.0
0.7
0.2
594
571
490
131
885
7.6
13.3
29
—
--
636
43
17
—
143
1,570
24
~
18
2,410
—
1,760
1,650
2,510
—
—
16
—
0.15
3
7.4
857
2.4
57
2,080
1.6
71
2.0
0.2
2,060
—
38
0
2,960
8.3
~
6-8
-------
D?"^ A 7"
RAF
Table 6-3CLASSIFICATION OF WATER
NAME
Concentration of total dissolved solids
ppm n £.. IL .
Based on salinity
Fresh
Brackish
Salty
Brine
Slightly saline
Moderately saline
Very saline
Briny 4)
Based on hardness
Soft
Moderately hard
Hard
Very hard 4).
0-1000
1000-10,000
10,000-100.000
over 100,000
1000-3000
3,000-10,000
10,000-35,000
over 35,000
Hardness as CaCO ) ppm
0-60 3
61-120
121-180
over 180
6-9
-------
within a region of general contamination will require relatively higher
concentrations of contaminants in comparison to comparable uncontaminated
areas.
No estimate of background concentrations of leachate indicators typical
for a geohydrological setting could be used in lieu of actual measurements.
The only way to ascertain the ground-water quality at a given site is to
measure it. However, man's activities, as previously mentioned, can
influence ground-water quality. A description of contaminants associated
with certain of these activities could be helpful as it would point out
those indicators which need to be delineated from unnaturally high back-
ground concentrations in order to trace leachte-enriched ground water.
The following sources of ground-water contamination are listed in Table 6-4
which summarizes their potential contributions of ground-water contaminants.
Their similarities to and distinctions from leachate should be carefully
noted so that interferences will be recognizable.
Highway deicine - Over 6,567,000 tons (5,962,000 tonnes) of deicing salts
were used nationwide in 1966-7. The most common salt in use is
sodium chloride, with calcium chloride use amounting to only 4 percent
of that of sodium chloride.
*
Open storage of salt or salt/sand mixtures may result in leaching of salt
with rainwater. The leachate after reaching ground water, will form a
plume of salt enriched ground water which could contaminate wells in the
vicinity. On the other hand, spreading of salt on the road results in
a more diffuse salt-enrichment of ground water. Wells located near major
highways have been affected by deicing salt.
6-10
-------
DRAFT
KJ
Table.6-4 CONTRIBUTION OF LANDFILL LEACHATE INDICATORS TO
GROUND WATER BY OTHER SOURCES
Highway Leaky Septic .-
Indicator deicing sewers tanks Mining Irrigation
Phosphate
Calcium M
Magnesium
Sodium H
Potassium
Ammonium
Chloride H
Sulfate
Nitrate
Bicarbonate
Iron
Manganese
Boron
Selenium
Zinc
Copper
Lead
Other h.m.
A4BAS
Phenols
PCB
Org N
PAH-HC.
TOC
BOD
Coliform
Virus
M
L
M
L
M
H
M
H
L
M
P
M
H
H
P
P
M P
M
M
L M
M
M
L H
M H M
H L
M
M H
H*
L
M
M
M
P
L
M
H
M
P
P
Land dis- Petroleum Feed-
posal sludge expl & dev lots
P
L
L
L
L
H
H
H
M
L
L
P
P
P
M
P
L
P
P
P
M
H
H L
M
M H
L
P
L
M
M
P
P
H = High
M =
L = Low
P = Potential
6-11
-------
Leaky sewers - Sewer pipes which have been In service over a period of
years are likely to be leaky. Sewage gases form acids which dissolve
concrete and mortar, usually the substance of older sewer pipes. When
the pipes are located In the unsaturated zone, raw sewage may leak and
percolate to the ground water.
Sewage contains some inorganic salts, sulfur, nitrogen, trace metals, and
suspended and dissolved organic compounds. Sulfur and nitrogen are
generally present as sulfide and ammonia. After entering the zone of
aeration, these ions are oxidized to sulfate and nitrate. Thus, sulfate
and nitrate are associated with leaky sewers In Table 6-4. The organic
matter exerts a large BOD and COD. Enteric organisims, bacteria and viruses,
are present in large numbers creating a potential for biological contamina-
tion. It has been estimated that approximately 500 million gallons of
sewage is lost annually in the U. S. through leakage. (2)
Septic tanks - Contaminants carried to ground water in percolating septic
tank effluent are similar to those from leaky sewers. The major difference
is that septic tanks have provided an opportunity for some anaerobic de-
composition. Thus, MBAS and BOD levels are reduced from those of raw
sewage. Again, percolation of effluent through the zone of aeration
converts ammonium and sulfide to nitrate and sulfate. A reduction of
dissolved oxygen in the percolate or ground water by a high BOD flow can
cause dissolution of iron, hence the iron rating in Table 6-4.
Unless the septic tank is within a couple of feet of the water table,
bacterial contamination should not be a problem. However, a septic tank
located in coarse-textured soil overlying a fractured rock aquifer might
6-12
-------
cause considerable bacterial and viral contamination.
Septic tanks in a density of one per acre or less are not likely to
significantly influence regional ground-water quality. As density in-
creases, these point sources of contamination blend together and result
in a general degradation of regional ground water.
Mining - A variety of contaminants are generated in leach-mining and
ore beneficiation which are specific to the mineral type and mine location.
Locations generating these contaminants would be obvious, so it is not
necessary to deal with them here.
A more general contamination problem is generated by wastes from strip
and shaft mining particularly as these methods pertain to coal. In strip
mining, overburden must be removed to expose coal or ore seams. The coal
is separated from waste rock and is washed. The wastes produced in these
processes are termed spoils and gob piles.
Frequently, the waste rock and mineral contains pyrite (FeS2), an iron
sulfide mineral. When exposed to air, pyrite oxidizes with the help of
iron-oxidizing bacteria. The oxidation produces sulfuric acid which keeps
iron in solution and frequently dissolves other heavy metals from waste
minerals. Drainage water from strip mine spoils or from mine shafts may
have a pH of less than 2. This acid mine drainage kills fish in surface
waters and produces a red-yellow scum that is unsightly.
The acid character of the spoils and gob piles prevents plants from covering
them. The resulting erosion continuously exposes new pyrite to oxidation.
Millions of tons of sulfuric acid are introduced into the environment each
6-13
-------
year from acid mine drainage. Large regions of Pennsylvania, West
Virginia, Ohio, Indiana, and Illinois have been contaminated from
coal mining wastes. Colorado has a similar problem from abandoned
metal ore mines.
Acid water can contaminate ground water with a variety of heavy metals
which it dissolves. Reduction of the ground-water pH also occurs creating
a more corrosive medium. Iron and/or manganese accompanying acidic water
add a metallic taste to water and cause staining of plumbing fixtures and
when it is used in laundering.
Irrrigation - Ground or surface water used for irrigation becomes more
mineralized as it percolates through soil and dissolves mineral and
fertilizer constituents. Irrigation water going to recharge carries an
\e><.l,^tfjv
enrichment of some or all of theAionsJ calcium, magnesium, sodium, potassium,
chloride, sulfate, and nitrate.
Continued irrigation increasingly mineralizes ground water. This enrich-
ment may become limiting to further ground water use. In California, there
are closed basins where ground water has been recycled by irrigation and
has become so mineralized it is approaching the limit of usefulness.
Land disposal of sludge - The literature on sludge chemistry has reported
all of the indicators listed in Table 6.4 as being present in one sample
or another. Concentrations range from parts per billion to percentages.
Sludge is applied to the land surface. Therefore, its influence on ground-
water quality is determined by the transport of its constituents through the
soil and underlying unsaturated zone. The contribution of landfill leachate
6-14
-------
indicators to ground water is calculated on the basis of sludge leachate
having undergone reactions in the soil and unsaturated zone.
Ammonium in sludge will nitrify and the portion that leaches will move
as nitrate. Most of the heavy metals and phosphate will probably be
retained in the soil and be in extremely low concentrations in percolate.
Bacteria have been studied after sludge application to land. Fecal coli-
forms exhibit a die-off rate which reduces their number to a negligible
population in a matter of 2-3 weeks. Movement through soil is usually
no more than a few c«n-fcr«oaW$. Viruses have been shown to be more in
soil, but are not likely to be a serious contaminant if digested sludge is
used.
Petroleum exploration and development - Brines are almost universally
associated with oil deposits. They are sometimes produced in greater
quantities than crude oil especially from older fields. Brine pits are
the most common waste disposal facilities. In theory, water evaporates
leaving salt accumulations. In practice, frequently brine leaks from the
pit and carries high concentrations of salt into underlying aquifers.
Sodium and calcium are the most common cations, with chloride, sulfate,
and nitrate 4X5- the most common anions. Some brine contains enough
bromide for economic recovery. Brine may also be used as a secondary
recovery injectant. As an indication of the extent of the problem, over
/0\
400 billion gallons of brine were produced in the U. S. in 1974.
Feedlots - Ground-water contamination from feedlots occurs principally
from leaching of nitrate. Some mineralization of infiltrating water may
also occur, but not usually to an extent that serious contamination results.
6-15
-------
Phosphate is a serious pollution hazard to surface water from feedlot
runoff. However, phosphate is retained in soil and doesn't usually
move into ground water. Of the heavy metals, zinc is present in the
highest concentration in manure. None of the heavy metals are in con-
centrations as high as those associated with municipal sludges of mixed
domestic and industrial origin. Ho appreciable contribution of manure
contained heavy metals to ground water is anticipated.
There are a couple of sources of ground-water contamination for which it
is difficult to assign specific chemical constituents. Waste lagoons
and oxidation ponds is one of these categories (Table 6.5). Such
facilities may contain almost anything of an inorganic or organic type
imagined. Therefore, in listing leachate indicators, probabilities are
given of their occurrence in lagooned and ponded waste leakage as it
enters the ground-water system.
Buried pipelines and tanks are another source of ground-water contamina-
tion. Probably the most common contaminants from these sources are
petroleum products. Chemical storage tanks have also been documented as
contributors of contamininants to ground water. Again, the probabilities
shown in Table 6.5 represent the probabilities of the given indicator
actually reaching ground-water.
6-16
-------
DH68^ jfiV F^ M^AM
RAF 8
Table 6.5 PROBABILITIES OF LANDFILL LEACHATE 'NDICATORS FROM
GIVEN SOURCES CONTAMINATING GROUND V/ATER
Indicator
Waste Iag6ons
and ponds
Buried pipelines
and tanks
Phosphate
Calcium
Magnesium
Sodium
Potassium
Ammonium
Chloride
Sulfate
Nitrate
Bicarbonate
Iron
Manganese
Boron
Selenium
Zinc
Copper
Lead
Other h.m.
MBAS
Phenols
PCB
QIB.N _
PAH-H^-
TOC
BOD
Coliform
Virus
II
III
III
1
III
II
1
1
1
III
1
1
II
II
II
II
II
II
III
1
II
II
III
II
II
III
III
III
III
III
II
III
III
II
II
II
III
III
III
III
III
III
III
II
II
III
1
III
III
1
1
1
in
in
I = Highly probable
II = Probable
III = Unlikely
B-17
-------
TABLE 6-6
LEACHATE INDICATORS
APPEARANCE
PH
Oxidation-Reduction Potential
Conductivity PHYSICAL
Color
Turbidity
Temperature
Odor
Phenols
Chemical Oxygen Demand (COD) CHEMICAL
Total Organic Carbon (TOG)
Volatile Acids Organic
Tannins, Lignins
Organic-U
Ether Soluble (oil & grease)
MBAS
Organic Functional Groups As Required
Chlorinated Hydrocarbons
Total Bicarbonate Solids (TSS, TDS)
Volatile Solids
Chloride
Sulfate
Phosphate
Alkalinity and Acidity
Nitrate-H
Nitrite-N Inorganic
Ammon ia—N
Sodium
Potassium
Calcium
Magnesium
Hardness
Heavy Metals (Pb, Cu, Ni, Cr, Zn, Cd, Fe, Mn, Si, Hg,As, Se, Ba, Ag)
Cyanide
Fluoride
Biochemical Oxygen Demand (BOD) BIOLOGICAL
Coliform Bacteria (Total, fecal; fecal streptococcus)
Standard Plate Count
6-18
-------
6.3 CHEMICAL, PHYSICAL AND BIOLOGICAL INDICATORS
A comprehensive listing of leachate indicator parameters has been prepared
and presented in Table 6.6. This listing is based on the composition of
leachate which was presented in Chapter 3 and reflects the most widely
used leachate indicators by researchers in the field and state regulatory
(4)
agencies.
The schematic diagram on Figure 6-1 and the list of leachate indicator
parameters in Table 6-6 represent the principle undesirable characteristics
of leachate from MSW. Its deleterious effects an ground and surface waters
become apparent. Just some of the effects include:
1. Soluble organics and some inorganics causing dissolved
oxygen depletion in surface waters.
2. Soluble constituents that result in objectionable tastes
and odors in water supplies.
3. The obvious health hazards connected with toxic materials
and heavy metal ions and microbiological contaminants in
excess of drinking water standards.
4. The effects of dissolved solids in excess concentrations
limiting the use of ground and surface waters, for drinking
domestic, industrial or recreational use.
These examples all point to the basic need for monitoring many of these para-
meters. The reader is referred to the EPA Handbook for Monitoring Industrial
Wastewater * ' and to the introductory remarks in Standard Methods ^ ' for
further discussion and background information regarding the undesirable nature
and potential effects of the various leachate indicator parameters.
6-19
-------
The actual selection and use of indicators for a particular monitoring
program will generally be de^i from the indicators on Table 6-6 and
will depend upon a number of considerations.
1. Type of Monitoring Network - I, II or III as was
presented in Chapter 4.
2. Susceptability to attenuation.
3. Background water quality.
4. Location of well being sampled - "A" Wells, "B" Wells,
or "C" Wells.
5. Purpose of Monitoring.
6. Other considerations including cost,regulatory standards
to be met, availability of laboratory equipment and man-
power, simplicity and precision of determination.
7. Type of refuse handled and other site-specific factors.
6.4 INDICATOR. GROUPS
Indicators can be categorized into various groups or levels of monitoring which
vary in degrees of information obtained in relationship to the purpose for
the monitoring. Three such levels widely used by researchers, engineers and
regulatory agencies are:
. Specific Conductance Measurements
. Key Indicator Analyses
. Extended Indicator Analyses
6.4.1 SPECIFIC CONDUCTANCE MEASUREMENTS
For monitoring ground-water quality and its fluctuations over a period of
time, specific conductance is a useful parameter for approximating the total
6-20
-------
amount of inorganic dissolved solids. The real value of specific conduc-
tance is that it can be performed easily and quickly, requiring little
training, with portable field equipment which is relatively inexpensive,
accurate and reliable (approximately $200.00).
Specific conductance has been successfully correlated with total dissolved
solids for monitoring leachate-enriched ground water. It also has been used
successfully to detect fluctuations and trends for ionic impurities in the
ground water. If conductivity is being used as an indicator of total
dissolved solids, it is absolutely essential that a correlation be obtained
for the specific land disposal site being monitored. Otherwise, gross errors
can be expected in data interpretation.
Availability of a conductivity meter at a site would allow an operator to
"spot check" monitoring wells at very frequent intervals (say weekly or monthly)
It can also be used advantageously during the sampling of a site to prioritize
wells to be sampled, where time and budget restrictions are a problem.
6.4.2 KEY INDICATOR ANALYSES GROUP
The intent of this monitoring group is to include highly sensitive analytical
parameters, which can be performed rapidly and accurately, at relatively
low cost, by personnel of minimum training, to yield reliable, useful data.
One should select a group of parameters which will provide information
regarding ionic, nonionic, inorganic, organic and suspended constituents of
the ground-water sample. Most of the parameters should lend themselves to
field analysis using portable equipment. Field analyses have the obvious
advantage of eliminating the necessity for low temperature and/or chemical
preservation of the sample, therby minimizing labor and deterioration effects
on the analysis which can result from sample degradation due to aging. This
6-21
'••3
-------
monitoring group can be performed at frequent intervals, with low cost,
manpower and equipment requirements.
The final selection of analytical parameters must consider the background
water quality, the pure leachate quality, as well as the hydrogeologic
influences. The group must therefore be site specific as well as remain
flexible to change at a site as may be dictated by data interpretation.
For discussion purposes, the following list of key indicators has been
widely used in the field to determine the presence of leachate:
. Specific Conductance
. pH
. Temperature
. Chloride
. Iron
. Color
. Turbidity
. COD
This group fits well the criteria for key indicators and, with the exception
of COD, can be performed rapidly using portable field equipment.
It is not suggested that all of the indicator parameters mentioned in this
list must necessarily be used together to determine the presence of leachate.
Rather, this is to be left to the judgment of the individual analyst. It
is possible, for instance, that results from just one of the analyses (i.e.
specific conductance) could indicate the probable presence of leachate. A
decision would then be made whether to run some or all of the remaining
parameters, or additonal tests to determine the reason for the high conduc-
tance value.
6-22
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Data obtained from indicator analyses have value in and of themselves, that
is, individual determinations will give valuable information regarding the
possible presence of leachate. In addition, data obtained from several
indicator analyses can be crosu-correlated and interpreted so that even more
insight can be gained about the nature of the contamination, over and above
what is obtained from the individual tests.
The following hypothetical examples serve to illustrate this point:
Example 1. A sample of ground water is analyzed and yields the
following results:
High levels of color and COD.
Low levels of iron, turbidity, and conductance.
These results could be interpreted as an indication of
the presence of an appreciable concentration of colored organic
contamination in a system which is low in soluble and suspended
inorganic contaminant levels.
Example 2. A sample of ground water is anlayzed and yields the
following results:
High levels of conductance, chloride, pH, and turbidity.
Low levels of COD, color, and iron.
These results could be interpreted as an indication of
the presence of an appreciable concentration of inorganic
materials, both suspended and in solution and a low concen-
tration level of organic materials.
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Kxamplc 3. A sample of ground water is analyzed and yields the
following results:
High levels of conductance, chloride, iron, color, and COD.
Low levels of turbidity and pH.
These results could be interpreted as an indication of
the presence of appreciable concentrations of both inorganic
and organic contaminants in acid solution and very low levels
of suspended materials.
Further interpretation of the indicator data must then consider background
water quality, hydrogeology, attenuation and other pollution sources in the
vicinity of the landfill in order to determine whether the presence of leachate
is indicated.
6.4.3
EXTENDED INDICATOR ANALYSES GROUP
Th«snonitoring group is a much more comprehensive group of analytical para-
meters. Table 6-6 presents a comprehensive extended indicator analyses
Croup which provides for a good characterization of the water samnle and
represents indicators commonly used by researchers and required by r.,any
regulatory agencies. (4) Performance of this monitoring group will obviously
he costly, requiring trained personnel and an adequately equipped sanitary
laboraboty. Very few of the parar-.eters can be analyzed with portable field
equipment thus requiring the utilization of acceptable storage and preser-
vation techniques.
There can be a number of reasons for performing extended indicator analyses.
The main reason is the need to perform additional analyses as a result of
problems which become known fron data. provided by the key indicator analyses
group.
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Additional testing, whether Instituted by a regulatory agency or the landfill
operator, should always be approached conservatively from both a technical
and cost standpoint. Arbitrarily requiring an extended program without
reasonable technical justification results in a very costly undertaking with
little or no regard to its cost benefit effecitveness.
An extended analysis program can only be justified when it can be demonstrated
that a basic indicator program does not have the necessary and sufficient
capability to assure the absence of leachate contamination or to provide
enough information to solve a specific contamination problem or yield required
background quality information. When background quality information is being
developed, a relatively large number of analytical parameters should be
investigated In order to choose the few most valuable ones which will consti-
tute the key indicator analysis program.
A sudden radical change in a key indicator may also point to the necessity
for extended analytical work. For example, indicator data might suddenly
indicate contamination by a non-specific organic material, as indicated by
an elevated COD value. In this case, the indication would be to perform a
number of analyses, such as wet chemical tests or even infra-red and gas
chromatography (if equipment Is available), :r . in order to determine which
specific compound or compounds caused the change In the COD. From a
regulatory standpoint, the nature of an extended analysis program would also
be related to the standards which have been set to assure the absence of
leachate contamination,' For example, suppose that a state regulatory agency
decides to adopt as its enforcement standard the U. S. Public Health Service
Drinking Water Standards of 1962. This would result in an extended analysis
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program which would at least require testing for twenty-four parameters,
four physical and twenty chemical.
As another example, suppose that a state regulatory agency decides to adopt
as its enforcement standards a series of seven physical and chemical para-
meters, (i.e. - PH, specific conductance, chemical oxygen demand (COD),
chloride, iron, color and turbidity). This program would per se constitute
an adequate key indicator program, thereby eliminating the need for an ex-
tended analysis program for regulatory purposes.
Thus, it can be seen that the concept of an extended analysis program is a
relative one. It is usually relative to regulatory requirements, or the need
for data, in addition to the key indicatbr program or specific contamination
problems. It must, therefore, be the task of the responsible engineers and
analysts to determine what will constitute an 'extended analysis program, if
any, for a given landfill site.
6.5 GUIDELINES FOR USING INDICATORS
For a given land disposal site, the selection and use of indicators will vary
with the background water quality, the differential attenuation that, may occur
and the well being monitored.
6.5.1 BACKGROUND WATER QUALITY MONITORING
6.5.1.1 New Land Disposal Site
For a new land disposal site, the background monitoring will define the natur-
ally occurring constituents in the ground water and contaminants from other
possible pollution sources that may be in the area. Section 6.2 presents a
good summary of the background quality one might expect to find in"different
geologic settings and with a variety of "other pollution sources." Usually,
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the background quality at a new site can be satisfactorily defined by per-
forming an extended indicator analysis group on an "A" well(s) that has
been installed at the site for this purpose. Section 4.2 discusses various
types of "A" wells in the different monitoring networks. It may be desirable
to have additional "A" wells if other pollution sources that may have a
significant impact on the ground-water quality at the site are suspected
where there is more'than one water-bearing zone to be monitored.
For the first sampling, the extended indicator analyses group should include,
as a minimum, all of the parameters on Table 6-6. Additional parameters
may be deemed desirable where applicable to define "other pollution sources"
in the area. In the case of the latter, the characteristics of other pollution
sources should be investigated in selecting any additional parameters for
monitoring. It is desirable to perform a few samplings (say 3 or 4) to ob-
tain a more statistically reliable data base for the long-term monitoring
prior to commencement of operations. As is usually the case, this is not
done due to time and economic considerations. Therefore, it is suggested
to at least collect additional data on a few selected key indicators which
will likely be used in the long-term monitoring. These can be done quickly
and cheaply and will provide valuable data in developing a statistically
reliable data profile (see Section 6.6).
While the "A" wells will establish the background water quality for the site,
it is also important to develop background quality data for each "B" and "C"
well. This is more important for larger landfills where the "A", "B", and
"C" wells are relatively far apart in respect to changes in geology and
other pollution sources which may influence their quality. Therefore, it is
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recommended that an extended indicator analysis group be performed on
all monitoring wells as soon as possible after their installation.
6.5.1.2 Existing Land Disposal Site
For an existing land disposal site, where solid waste has already been
landfilled, the background quality monitoring should include leachate
contamination that may have already occurred on the site. Monitoring in
this case must then involve the "A", "B", and "C" wells installed at the site,
where as before the "A" well will define the natural background quality,
while the "B" and "C" wells define existing leachate contamination.
Here, the quality of the "B" well becomes especially significant in selecting
the key and extended indicators for the monitoring program. This well will
detect the leachate contaminants that are entering the saturated zone. The
analysis of this well will also provide valuable information about the unknown
past history of a site. For example, an old site may have disposed of hazard-
ous wastes in the past which could result in significant concentrations of
exotic contaminants not normally attributed to municipal solid waste (i.e.
certain heavy metals or pesticides). Depending upon the extent of the problem
and the degree of potential hazard to the public, a decision can then be
made as to whether to include additional parameters into the monitoring
program as key or extended indicators. In any event, analysis of the "B"
well will represent the "worst case" in terras of leachate contamination at
a particular site, and can provide a basis for including or excluding in-
dicator parameters.
6.5.2 ON-GOING MONITORING
The on-going monitoring program should consist of the judicious use of repre-
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sentative key and extended indicator analyses groups, the former being
run at more frequent intervals and the latter less frequently for verifi-
cation purposes. The key indicator group is designed for the primary
purpose of determining presence or absence of leachate contamination and as
a "check" on quality fluctuations. The extended indicator group is designed
to provide verification of non-specific key indicators (i.e. COD or specific
conductance) and for legal purposes in an enforcement action.
The on-going program will, of course, involve the monitoring of the "A",
"B" and "C" wells. After establishing some background quality data for
the various wells (whether it be one or a series of samplings), the most
representative indicators for the site should be selected. In doing this,
one must consider the background quality data, the constituents of the
leachate, and the potential influence of attenuation. The information
presented In Chapter 3 on attenuation, and In Chapter 6 on background water
quality provides some valuable guidelines for selecting indicators.
As an example, suppose the natural background quality is high in iron or
total dissolved solids. In this case, the value of iron and specific con-
ductance as key indicators of leachate contamination is lessened because
of the high concentrations that would be required to distinguish from back-
ground. Or, there may be another pollution source in the vicinity that is
affecting the background quality of the ground water, such as deicing of
adjacent highways, or local septic tanks, or leaky sewers. These, too, might
serve to lessen the value of various parameters as leachate indicators.
Section 6.2.1 presents some very useful information on background water
quality which should be used as a guide in indicator selection.
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Susceptibility to attenuation in different soils would also affect the
value of the various parameters as indicators of leachate. The information
presented in Section 3.2 and Table 3-2 can be used as a guide in indicator
selection for a particular disposal site. Table 3-2 points out the sig-
nificance of chloride as an indicator due to its freedom from attenuation.
The key indicator program should be followed as long as no presence of
leachate is detected or where leachate is already present, no significant
fluctuations in the data are observed. Another consideration here might
also be the regulatory agency's requirements, as many states do require a
periodic (say, annual) testing for an extended analysis group, regardless
of the monitoring trends being observed. In most cases, all "A", "B", and
"C" wells at the site should be.included in the key indicator program.
However, this is not to be considered an ironclad rule of thumb. Many
large acreage land disposal sites may have as many as 20 monitoring wells.
In these cases, one may elect not to sample all 20 wells at.each sampling,
but to rotate sampling to include say 5 wells each sampling date. Therefore,
in the case of quarterly sampling, each well would be sampled once per year.
In this case, each sampling should include at least one of each well type,
that is, an "A", "B", and "C" well.
The convenience of the specific conductance test can be a valuable asset
in this case. Ability to be tested quickly, with a field instrument may
allow at least a specific conductance reading on all 20 wells at each sampling
date. The need to pump out the well prior to sampling would limit the use
of the specific conductance given time restrictions. The specific conductance
reading provides the added dimension of deciding on the spot which wells
should receive priority for sampling. Having the specific conductance data
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iirofilc on hand for quick reference, the field technician can compare today's
reading "ith the profile which may show a significant change and worthy of
further investigation. So, a combination of a routine rotational sampling
sc-herlule, subject to possible modification due to a significant rh.mgb In
specific conductance, would comprise a sound rationale to the use of the
key indicator group.
If a significant change is observed in a key indicator parameter or parameters
(i.e. - increase in specific conductance), the possibility of leachate contamina-
tion should be suspected and a plan for further investigative and corrective
action should be instituted immediately. This plan should include additional
sampling and analytical work as determined by the key indicator data obtained,
to serve as a data base for developing a satisfactory correction action to
eliminate the cause of the contamination problem and to nonitor the effect
of implementing the same.
Assuming that a leachate contamination problem has been discovered by the
key indicator program and corrective action iinplenented, sampling and indicator
testing should be instituted on an increased level of frequency, with the
possible inclusion of additional parameters. This should be continued until
there is reasonable certitude that conditions have returned to normal and will
probably remain so. At this point, a re-assessnent of the key indicator
analytical program should be made. It should then be decided whether to re-
institute the program in its original form or to initiate it in a modified
form, based unon experience gained in solving the contamination problem.
The following example will serve to illustrate this approach:
Suppose that sulfate was found to be a principal contributing
contaminant which had caused a high specific conductance reading.
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It might then be decided to test for sulfate, for a limited time,
in addition to the other parameters of the key indicator program.
Valuable data could be collected in this manner to show sulfate/
conductance ratios which could be used as a guide in monitoring for
future problems.
Obtaining background quality data and further investigating a particular problem
aie the principal technical reasons for implementing an extended indicator
analyses group. In the le&al sense, enforcement data needs may require extended
indicator analyses data. Administratively, many regulatory agencies will re-
quire (say, annual or bi-annual) gStwipJarM for an extended indicator analyses
group.
In any case, the conservative use of the extended indicator parameters should
be kept in mind due to the relatively excessive cost and manpower requirements
associated with their performance. The fact that the extended indicator
parameters are basically serving to verify the results of the key indicator
parameters, should provide a basis of a rationale for selecting and ranking
the former. In other words, a significant fluctuation in a particular key
indicator would warrant further investigation by a select group of extended
parameters and not automatically the entire extended indicator analyses group.
The implementation of the extended indicator analyses group should be a
monitoring well specific decision. For example, a quality change in one "C"
well should not immediately require the testing for extended indicators in
all of the "C" wells.
The following examples of relationships between key and extended indicators
serve to illustrate the point :
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1. Specific Conductance;
A significant change in specific conductance would be an
indicator of possible chances in levels of one or more of
the following extended indicator parameters: pll, total
dissolved solids, chloride, sulfate, phosphate, alkalinity,
acidity, nitrogen series, sodium, potassium, calcium, mag-
nesium, hardness, heavy metals, cyanide, fluoride, and COD.
2. A sionifleant change in chloride concentration would be an
indicator of possible changes in levels of one or more of
the following extended indicator parameters: specific con-
ductance, total dissolved solids, pH, acidity, and metal ions.
3. A significant change in iron (total) concentration would be
an indicator of possible changes in levels of one or more of
the following extended indicator parameters': specific conduc-
tance, pH, total dissolved solids, chloride, sulfate, phosphate,
manganese, and fluoride.
4. A significant change in color would be an indicator of possible
changes in levels of one or more of the following extended in-
dicator parameters: COD, TOC, tannins, lignins, organic N,
total dissolved solids, pH, iron, BOD and conductance.
5. A significant change in turbidity would be an indicator of possible
changes in levels of one or more of the following extended indicator
parameters: pH, conductance, COD, TOC, tannins, lignins, total
suspended soilds, phosphate, alkalinity, acidity, calcium, mag-
nesium, hardness, heavy netals, fluoride, and BOD.
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6- A significant change in COD would be an,indicator of possible
changes in levels of one or more of the ^following extended
parameters: HOD, pH, conductance, TOG, volatile acids,
tannins, lignins, organic-N, total dissolved solids, total
suspended solids, volatile solids.
In a practical situation, several of the key indicators will nost probably
i
show variations at the sane time. Therefore, looking at combinations of key
indicators will provide additional information for the analyst to define
the chemistry of the system involved and further assist him in specifying
additional extended indicators for analysis.
6.6 MONITORING FREQUENCY
The sampling schedule for a land disposal site should maintain flexibility
for modification. Monitoring frequency is greatly influenced by many factors
as listed,below:
1. Characteristics of ground-water flow.
2. Location and purpose of the particular monitoring well.
3. Climatological characteristics.
A. Trends in the monitoring data.
5. Local and institutional data needs.
6. Other considerations.
Obviously, the hazardous nature of the leachate and what is being threatened
(i.e. a single domestic well versus an entire municipal water supply) will
to a large degree dicatate the monitoring effort.
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6.6.1 CHARACTERISTICS OF GROUND-WATER FLOW
The principal characteristic of concern in selecting a sampling frequency
is the rate of ground-water flow at the land disposal site. As was dis-
cussed in Chapter 4, the flow rate will be primarily dependent on the
aquifer porosity, permeability as well as the hydraulic gradient existing
at the site. The aquifers were generally categorized by porosity into
intergranular porosity, fracture porosity, and solution porosity with
ground-water flow rates ranging in orders of magnitude from a few feet
per year in an impervious intergranular porosity aquifer to tens of
feet per day in the more unpredictable fracture and solution porosity
aquifers.
The higher the rate of ground-water flow, warrants more frequent monitoring.
Two extreme examples would be an intergranular porosity aquifer with
impervious clay soils and a fracture or solution porosity aquifer with
unpredictable and high flow rates likely. For an example, suppose the
closest "C" well is 100 feet from the landfill and the closest downgradient
property line or domestic well is 300 feet away. At the site with the clay
soils, it would be senseless to frequent sampling if, theoretically, it
would take ten to twenty years for any leachate-enriched ground water to
even reach the well. Here, after establishing background quality, an annual
or bi-annual monitoring of the well with select key indicator parameters
would suffice. In the latter case, however, it is possible that contaminants
could migrate off of the property in a matter of weeks or months. Here,
a quarterly monitoring with key indicators, with, perhaps, a more frequentfd^,)
spot checking with specific conductance would be warranted. As was discussed
earlier in the Chapter, the extended indicator group would be utilized as needed,
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Most landfills will fall between these two extremes, but one can see that
careful consideration must be given to the flow rate and the distances
involved to select a frequency which will not miss an environmental
occurrence. '
In a similar sense, the monitoring well would be influenced by the vertical
flow rate of leachate-enriched ground water. For example, suppose a disposal
site is underlain by a sand aquifer with a relatively high ground-water flow
rate, but it is separated from the landfill by a thick layer of impervious
clay. Here, a concentrated monitoring effort of the "C" wells in the
aquifer would not be justified until the "B" well detected that contaminants
have travelled through the clay layer and reached the aquifer.
6.6.2 LOCATION AND PURPOSE OF THE MONITORING WELL
The distance that a monitoring well is located from the land disposal site
and its depth will influence monitoring frequency. For example, there may
be a case where a line of "C" wells are placed along the property line for
legal and administrative reasons due to ground-water protection laws.
There is little need to concentrate on monitoring these wells until the
monitoring results of closer "C" wells presents some reason to believe
that leachate contaminants may be approaching close to the property line.
Only minimum monitoring of these wells to establish background quality and
meet regulatory requirements would be justified. Anything more than an
annual frequency would be considered wasteful.
Another example might be a well located in deep water bearing zones separated
from the disposal site by other aquifers and aquicludes. Chapter 4 depicts
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examples of this (i.e. coastal plain) where there are a series of alternating
aquifers and aquicludes. For institutional reasons, or regional water planning
purposes, a monitoring well may be placed in a deep aquifer which has almost
no chance of being contaminated by the land disposal site. After an initial
sampling, or, perhaps, two for background purposes, such wells would only
deserve attention every two or five years, or, of course, in the unlikely
event that other monitoring results cause reason for concern.
6.6.3 CLIMATOLOCICAL CHARACTERISTICS
Jn setting up the initial monitoring schedule for a particular site, one
should analyze the fluctuations in leachate generation that occur over the
year. The water balance method, which was presented in Chapters 3 and 5,
is a very useful tool for this purpose. As an example, suppose it is
desired to perform quarterly sampling. Instead of arbitrarily assigning
a sampling date every third month, most of the monitoring effort should
be concentrated either during and/or after those periods of the year of
v
greatest leachate generation. The reflection of the actual sampling dates
should also take into account the well location and depth, ground-water
flow rate, saturation condition of the landfill, and other factors to
project approximate log times that may occur between first appearance of
leachate and its impact on the monitoring well.
6.6.4 TRENDS IN THE MONITORING DATA
The three factors presented above (ground-water flow rate, well purpose
and location and clinate) will be used in establishing monitoring frequencies
at the outset. However, monitoring frequencies should never be considered
ironclad, but should maintain flexibility for modification to respond to
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fronds in the monitoring data.
As .in example, suppose a spot check with a specific conductance meter indicates
a significant change in the water quality at a particular well. Further
investigation with additional key and extended indicators would be desired
immediately, regardless of when the next sampling is scheduled. Concentrating
on this well might also reduce the frequency at another well whose recent
data has not shown significant changes in water quality.
6.6.5 LEGAL AND INSTITUTIONAL DATA NEEDS
Monitoring frequencies at a site may also be altered for legal and institutional
J» ,
reasons. As an example, suppose an enforcement action is initiated against
a landfill. In order to strengthen their case, attorneys for both the state
and the disposal site may request that, all of the monitoring wells be monitored
for an extended indicator analyses group.
6.6.6 OTHER CONSIDERATIONS
Other reasons for modifying the monitoring frequencies at a site would include,
. complaints from neighboring residents.
. an unusually severe climatological event, such as a
hurricane with large amounts of rain in a short time
period.
. a sudden change in or addition of an "other pollution
source", such as an oil spill adjacent to the property.
. an unusual operational occurrence, such as the illegal
and/or improper dumping of a large volume of liquids at
a site*
A properly planned monitoring program will allow for modification in sampling
schedules to respond to the above-mentioned occurrences.
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6.7 COST CONSIDERATIONS
In selecting indicator parameters and sampling frequencies, it is important
to be mindful of relative costs for performing the monitoring. The three
basic levels of indicators used for monitoring presented earlier, vary not
only in the depth of analytical data provided but also in the costs for
sampling and analysis.
Specific conductance is so valuable because it is so inexpensive to perform.
Being analyzed with a portable field meter, the analytical cost is merely
the few extra minutes required by the technician to do the test at the site.
The meter, itself, is relatively inexpensive, cost approximately $200.00
(1976 prices). The sampling costs are also low primarily because it is not
necessary to collect and preserve samples for the laboratory thus lessening
the amount of bottles to be carried and the time for adding sample preserva-
tives. This advantage would be somewhat lessened where pre-pumping of the
wells is? done. There is no way of estimating sampling costs and time require-
ments since they are site specific depending upon accessibility and number
of wells, as well as the pre-pumping (If necessary), and sample withdrawal
method used. For order of magnitude comparison purposes only, a typical
commercial laboratory would charge approximately $3.00 per sample for a
specific conductance analysis (New York Area, 1976 prices).
A typical key indicator analysis group (i.e. specific conductance, PH, tempera-
ture, chloride,iron, color, turbidity, and COD) would be more expensive for
sampling and analysis. Like specific conductance, all the others, except
COD, can be run in the field with portable equipment. Sampling time will
be increased by the additional equipment and analyses required, the time to
collect, store and preserve the COD sample. Where one man could manage nicely
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with specific conductance measurements, an assistant may be desirable
in monitoring for the key indicators depending upon the number and
accessibility of wells to be sampled and the sample withdrawal awl hod
used. Adverse weather conditions may also necessitate transporting '
samples back to the laboratory for analyses, where specific conductance
could still be done in the field. For order of magnitude comparison
purposes, a typical commercial laboratory would charge approximately
$50.00 per sample for the key indicator analyses listed (New York Area,
1976 prices), exclusive of sampling.
A typical extended indicator analysis group, such as listed in'Table 6-6,
would be the most expensive level of monitoring for both sampling and
analysis. With the exception of some key indicators which might be run
in the field, all the indicators require proper storage, preservation-and
transport of samples to the laboratory for'analysis. This will require
additional sampling time and possibly additional manpower to perform
properly and efficiently in the field. Of course, adverse weather conditions
may further complicate sampling efforts.
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TABLE 6-7
COMPARATIVE COSTS OF
INDICATOR ANALYSES*
Monitoring Group
Specific Conductance
Approximate Cost of Analysis +
Per Sample ($)
$ 3.00
Key Indicators
$50.00
Extended Indicators
$600.00-$700.00
Mote; It should be noted that there is an economy of numbers relative
to both sampling and analysis. Appreciable quantity discounts are usually
available for different levels of sampling and analysis. Additional
savings can usually be realized through the use of long-term sampling and
analysis contract.
* A comparison of sampling costs has not been made due to its extreme
site specificity - such a comparison should consider the number and
accessibility of wells, weather conditions, whether or not the wells
will be pre-pumped prior to sampling, and the pre-pumping and sample
withdrawal methods uses.
+ Based on January 1976 rates of a typical commercial laboratory in
the New York Area. Refer to Chapter 3 for laboratory manpower re-
quirements for analyses.
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Again, for order of magnitude comparison purposes, a typical commercial
laboratory would charge approximately $600.00-$700.00 per sample for the
extended indicator parameters listed in Table 6-6, exclusive of sampling.
Table 6-7 summarizes the cost of analysis for the various monitoring groups
discussed above. As noted, no comparisons of sampling costs has been
made due to its extreme site specificity. In general terms, however, the
sampling costs do increase as more indicators are added and that the sampling
cost increases are magnified if pre-pumping of the wells is performed.
6.8 DATA MANAGEMENT
6.8.1 GENERAL
In a given sanitary landfill, appreciable quantities of data relative to
ground-water quality will be generated over a period of time. Several
factors govern the amount of data produced among which are the number of
monitoring wells, the number of parameters to be tested and the frequency
of testing, both scheduled and unscheduled (response to operational problems).
As a hypothetical case, let us assume that there are 20 monitoring wells in
a given landfill and that the following tests are performed in a given year:
Testing Category No. of Parameters No. of Wells No. of Tests
Annual-Extended 30 20 600
Quarterly-Indicator 10 20 600 (200 x 3)
Problem-Unscheduled 30 20 6QQ
Total 1,800
The total number of tests performed in the landfill over a period of one year
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will be 1,800. This figure could approach 20,000 over a 10-year period.
This amount of raw data must be processed, interrelated, statistically
analyzed amd stored in readily retrievable form so that it will be of
maximum value for quality control, engineering and legal purposes.
The use of digital computer treatment would appear to be an excellent tool,
both rapid and cost-effective as a management information system in the
handling of this type of data. Other approaches to data management could
entail manual processing, storage and retrieval of the data in the form of
tables, charts and graphs which can show parameter levels and trends
relative to standard values. In both cases, the statistical handling and
use of analytical data for quality control purposes, in the form of ranges,
means, standard deviations, parameter ratios and control charts will be
important.
The technological state of the art of land disposal is still relatively
young and is highly dependent on monitoring for its development. Even if a
particular design operational strategy is successful at one site, it cannot
be automatically assumed acceptable for all sites due to the extreme site
specificity which is fundamental to land disposal of solid waste. Again,
monitoring becomes critically important. Thus, the parameters monitored
and the significant results obtained from the monitoring program will be
critically evaluated in assessing a site and related design and operational
approaches and in deciding upon modification. Because of the significance
which may be placed on the results of the monitoring program, it should be
the desire of the landfill management to understand and attempt to identify
the causes of fluctuations in monitoring data obtained. Incorrect inter-
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pretation of monitoring results may result in unnecessary expenditures
or in a false sense of security.
The variability of the indicator parameters measured in a monitoring program
may result from various phenomena, some of which are listed below:
1. Natural fluctuations in the background water quality.
2. Occurrence of another pollution source which might cause
the background water quality to fluctuate.
3. Attenuation taking place in the subsurface environment.
, ;
4. Climatological variations.
5. Operational deficiencies, incidents and modifications.
6. Experimental errors in the analyses of measured parameters.
7. Sampling method utilized.
Variations in the background water quality will occur with location and time.
Such variations recorded in the "A" wells should be fingerprinted statistically
to allow for more accurate interpretation of the data fluctuations recorded
at the "B" and "C" wells. In the same vein, fluctuations in background
quality may be aritficially induced by another pollution source. As was
stressed earlier, such occurrences must be carefully recorded because of their
effect on monitoring data interpretation. As was discussed in Chapter 3,
attenuation and Climatological variations will have a definite influence
on time and distance changes in monitoring data.
Operational factors will have a definite influence on the monitoring data
and its evaluation and should be carefully documented. For example,
operation changes, such as, type of wastes, a sudden disposal of a large
quantity of liquid wastes, a deficiency in cover, or construction of the dikes,
6-44
-------
diversionditches and the like, could all significantly affect monitoring
results and should be carefully described with dates recorded.
The results of the analysis of a sample, by the same or different technicians,
using the same laboratory techniques often fluctuate widely. Even very
accurate laboratory analysis cannot prevent a relatively wide range in
determined values of parameters,such as BOD, which may experience experi-
mental error as high as *20%. Variations will also exist with alternate
analytical methods, especially field versus laboratory methods. This becomes
even more significant for concentrated leachate samples. Where interferences
further complicate analysis. All of this information must be carefully
recorded because of its significance in data interpretation. A more
detailed discussion on analytical methods is presented in Chapter 8.
Differences in the sampling method utilized will be important for monitoring
data evaluation due to the variations that can be created. Was the well
flushed out prior to obtaining a sample? Was the sample collected aerobically
or anaerobically? Was the sample properly preserved? How much time elapsed
i
between sample collection,*analysis? Who did the sampling? It is important
to know all of this information and understand /TS implications in
evaluating the monitoring results.
All of these possible causes in variations should be carefully recorded and
identified for proper evaluation of the monitoring results. It will be
important for the monitoring program to distinguish between fluctuations
which are significant and attributable to the landfill thus requiring some
form of remedial action versus those variations which are insignificant or
not attributable to deficiencies at the landfill. Of course, a complicating
6-45
-------
feature for a land disposal site, unlike in water and air pollution, is
the time lag which inherently exists between cause and effect. For example,
it may take months or years for a fluctuation observed in an "A" or "B"
well to reach a distant "C" well thus often complicating and retarding
data interpretation.
6.8.2 APPLICATION OF STATISTICS
In the Handbook for Monitoring Industrial Wastewater. USEPA, 1973,
the value of statistics in monitoring is discussed:
"Statistics aid in the development of general laws resulting from numerous
individual determinations which, by themselves, may be meaningless. The
resulting relationships are part of the fundamental function of statistics
which expresses the data obtained from an investigative process in a con-
densed and meaningful form. Thus, the average or mean is often used as a
single value to represent a group of data. The variability of the group of
observations is expressed by the value of the standard deviation and trends
in concentrations during the monitoring process are expressed in the form
of regression coefficients.
In general, the concern is with the treatment of the collected data. The
accuracy oA. usefulness of these data is greatly enchanced if a full under-
standing was involved in generating the facts. The balance between use of
statistical methods and evaluation based upon physical understanding is
extremely important. The use and value of statistics decreases as physical
understanding increases. Specifically, the difficulty lies in separating
chance effects from valid occurrences. With the knowledge of basic pro-
bability theory and the use of statistical techniques, such as Least Squares
Curve Fitting, Analysis of Variance, Regressive and Correlation Analysis,
Chi-Squared Goodness of Fit, and others, it is possible to construct mathe-
matical models and curves of almost any level of precision desired. Such
techniques help to evaluate information having wide variations, so that
an estimate of the best value of the parameter being measured can be assigned;
and also to assess the precision of that estimate. Statistical procedures
may also help in identifying errors and mistakes and are helpful in comparing
sampling methods and procedures and in evaluating waste loadings from different
process schemes."
Evaluation based upon physical understanding is especially significant for
monitoring of n land disposal site due to the extreme site specificity of the
various phenomena involved.
6-46
-------
Probably, the major use of statistics in a monitoring program is to
i-orrol;itu thu data for the proper choice of statistical parnraeLer.s (me.-m,
range and standard deviation) for the specific indicators for evaluation
and comparison purposes.
Statistics and data analyses are very broad topics and are beyond the
scope of this manual. The above-referenced EPA Handbook^ ' cited several
good references on statistics and these have been included in the bibliography
at the end of this chapter for additional reading where a statistical approach
is desired. It should be emphasized that rules and formulas for data
analyses are many and they must be chosen wisely and applied correctly to
be of value.
6.8.3 INDICATOR DATA PROFILES
Once a monitoring program has been in operation for an appreciable period
of time, the data obtained from it can be used to provide specific analytical
profiles for ground water and/or surface water for a given landfill site.
These profiles will be characterized by data from a number of sampling points
within the landfill and will reflect the influence of the various phenomena
which were discussed earlier that result in fluctuations in the indicator
parameters. Statistical analyses of the profiles will provide such important
statistical values as normal ranges, means and standard deviations for each
of the indicator parameters.
Quality control data of the landfill site can be obtained from the profile
data. This could take the form of control charts for the various parameters
which would indicate whether the operation was "in control" or "out of control
relative to upper and lower control limits provided by the control chart.
6-47
-------
SL.-illsl I»:s «':in pLay nn Important rolo In tho. correlation of specific
parameters, especially in the case of specific conductance to other
parameters such as total dissolved solids. Reference 5 presents an
excellent discussion on the statistics for correlation of specific
parameters. The data profile will also provide an insight into the inter-
relationships of the various key indicator parameters in the form of normal
ratios (i.e. conductance, total dissolved solids, iron, color, etc.)
which should be developed for a cost effective monitoring program. When
enough data are obtained on indicator parameter ratios (i.e. conductance,
total dissolved solids, etc.) for a given landfill site, statistical values
of range, mean and standard deviation can be developed, as is done for the
individual indicator parameters themselves. This information can be used
as a valuable statistical tool for quality control of the landfill and as
an aid in the diagnosis of leachate contamination problems and their probable
causes.
An indicator program, based on sufficient background quality data and on-
going statistical information, should provide a basic, cost-effective, reliable
monitoring tool for the quality control of a landfill.
In a monitoring program, data profiles can be used in a variety of ways, some
of which are discussed below:
-I- Concentration of the various indicator parameters versus time
for each monitoring well.
This is perhaps the most common use of a data profile in moni-
toring programs. It provides an immediate visual picture of the
trends in quality and is nicely defined with the basjc statistical
values (mean, range and standard deviation). It provides a
6-48
-------
valuable tool in comparing monitoring results of the "A",
"B" and "C" wells for operational and enforcement purposes.
It provides a readily available and convenient tool for
comparing water quality trends to trends and occurrences in
the various phenomena that influence the ground-water quality
which were discussed earlier in this section.
2. Concentration of the various indicator parameters versus
distance from the landfill. This type of profile would be
constructed by plotting the data for selected indicator
parameters which are obtained on a particular date for the
various "C" wells located at different distances from the
landfill. The quality of the "B" well would represent the
concentration at zero distance from the landfill. Chapter 3
(Section 3.2.4) discussed the use of this type of profile in
the measurement of attenuation at a land disposal site. Figure
3-1 shows an example of this profile.
3. Other profiles providing "physical understanding" information.
In the evaluation of the monitoring data obtained at a land
disposal site, it would be of value to be readily accessible to
information on the phenomena which may be the potential cause
of fluctuations and trends in the monitoring data. This might
include a water balance profile and a "chronological events"
profile of important occurrences. A water balance profile, such
as shown in Figure 6-2 could be developed for each site as part
of the permit applications or for several representative "typical
sites" throughout the state. The actual quantities are not as
6-49
-------
important as the trends they would depict. A profile of
"chronological events" might look like Figure 6-3 and
could be kept on file and up-to-date easily by the inspec-
tion and monitoring personnel. Reference to such a profile
would be of obvious value providing physical understanding
in evaluating monitoring results. It should be recognized,
however, that one must be mindful of the time lag between
cause and effect that is inherent at land disposal sites,
when using such profiles in the evaluation of monitoring
results.
6-50
-------
01
Si A* SIMSA
-------
CHAPTER 6 - REFERENCES
1. Field, Richard, E.J. Strugeski, 11.E. Masters, and others.
1975. Water pollution and associated effects from street
salting. Pages 317-340 in W.J. Jernell and Rita Swan, eds.
Water pollution control in low density areas. University
Press of New England, Hanover, New Hampshire.
2. Roux, Paul H. 1975. Personal communication. Geraghty &
Miller, Inc., Port Washington, New York.
3. MacCallum, Douglas R. 1975. Personal communication. Geraghty
& Miller, Inc., Port Washington, New York.
4. Chian & DeWalle, 1975, Compilation of Methodology for Measuring
Pollution Parameters of Landfill Leachate, University of Illinois
USEPA, Cincinnati, Ohio.
5. Handbook for Monitoring Industrial Wastewater, U.S. Environmental
Protection Agency, Technology Transfer, August 1973.
6. Standard Methods for the Examaination of Water and Wastewater,
13th Edition, American Public Health Association, 1970.
ADDITIONAL READING
1. Handbook for Analytical Quality Control in Water and Wastewater
Laboratories, EPA, Technology Transfer, 1972.
2. Eckenfelder, W.W., Industrial Water Pollution Control, McGraw-Hill
Book Co., 1966.
3. Eckenfelder, W.W., Water Quality Engineering for Practicing Engineers,
Barnes & Noble, Inc., New York, 1970.
4. Neville, A.M. and J. B. Kennedy, Basic Statistical Methods for Engineers
and Scientists, 4th Printing, International Textbook Co., Scranton,
Pennsylvania, 19700
5. Standard Methods for the Examination of Water and Wastewater, 13th
Edition, American Public Health Association, 1970.
6. Velz, J.C.C., "Graphical Approach to Statistics", Water and Sewage
Works, 1950.
-------
ERELIMJNARY
CHAPTER 7
SAMPLING. STORAGE AND PRESERVATION
7.1 INTRODUCTION
The sampling of ground and surface waters associated with sanitary landfill
monitoring is a critically important operation. The analytical results
obtained from the samples and the subsequent decisions which are based on
the analytical data, are vitally dependent upon the validity of the samples
obtained.
Every effort must be made to assure that the sample is representative of the
particular body of water being sampled. A detailed sampling plan, acceptable
to all interested parties, should be developed prior to any sampling operations.
The physical, chemical and bacteriological integrity of the sample must be
maintained from the time of sampling to the time of testing in order to keep
any changes at a minimum. The time between sampling and testing should be
kept at the absolute minimum which is practicable.
7.2 SAMPLE COLLECTION
The following, from ^Standard Methods p. 36, is a useful guide:
"A record should be made of every sample collected and every
bottle should be identified, preferably by attaching an
appropriately inscribed tag or label. The record should
contain sufficient information to provide positive identi-
fication of the sample at a later date, as well as the
name of the sample collector, the date, hour and exact
7-1
-------
location, the water temperature, and any data which may
be needed in the future for correlation, such as weather
conditions, water level, stream flow, or the like. Sam-
pling points should be fixed by detailed description,
by maps, or with the aid of stakes, buoys or landmarks
in such a manner as to permit their identification by
other persons without reliance upon memory or personal
guidance Samples from wells should be
collected only after the well has been pumped for a
sufficient time to insure that the sample will represent
the ground water which feeds the well. Sometimes it will
be necessary to pump at a specified rate to achieve a
characteristic drawdown, if this determines the zones from
which the well is supplied. It may be desirable to record
the pumping rate and the drawdown as part of the sample
record."
The quality of water pumped should equal approximately 3 to 5 well volumes.
If the well is pumped dry, sufficient time should be allowed for full recovery
prior to sampling.
7.2.1 SAMPLE COLLECTION TECHNIQUES
Various water withdrawal techniques were discussed in Chapter 5 including
vacuum pressure and bailing methods. The important underlying principle,
of course, being to obtain a representative sample of the ground water and
to minimize degradation. If the well depth is within pumpable limits, a
vacuum sampling technique can be used to obtain the sample under anaerobic
conditions. Figure 7-1 shows a typical vacuum sampling technique using a
vacuum pump and portable generator, used successfully in Orange County,
Florida. Vacuum can also be supplied from an automobile or truck
engine or a hand pump manifold which could replace the vacuum pump/portable
generator combination. Note in Figure 7-1, a 1/2-inch tube is permanently
installed in the monitoring well which would eliminate the possibility of
cross-contamination between wells.
7-2
-------
o
c\j
C\4
rr
VACUUM
CHAMBER
PORTABLE
GENERATOR
•CONCRETE
COARSE BUILDERS SAND
.010 WIDTH
DETAIL
WELL SCREEN SLOTS
FIGURE 7-1 Profile Of Shallow Sampling Well.(REF. 1)
7-3
-------
With a pressure-type sampling method, such as the type shown on Figure 24
(Chapter 5), the sample is obtained by connecting the sample! bottle directly
to the 1/2-inch water discharge outlet. To insure anaerobic conditions, the
sample bottle should be flushed out with an inert gas prior to collecting a
sample. The built-in feature of this method, being used to both pre-pump
and sample the well can effect considerable savings on labor and also
eliminate the possibility of cross-contamination between wells, as can occur
with portable pumping and sampling devices. They are also of notable value
in obtaining bacteriological samples where external sources of contamination
must be avoided.
Bailers are also used to collect a sample. A Kemmerer water bottle sampler,
as shown on Figure 7-2 is a bailer commonly used. In transferring the sample
from the sampler to the sample bottle, contact with air and agitation of the
sample should be minimized slow and careful transfer, placing the tip of
the sampler's exit tube to the side of the sample bottle is recommended.
To minimize cross-contamination, the bailers should be thoroughly flushed
out with tap vater&with the first sample from the next well to be sampled
prior to collecting the sample for analysis.
Samples for bacteriological examination must be collected in sterile containers.
Detailed sampling procedures for bacteriological samples are given in Stan-
dard Methods , 13th Ed., pp. 657-660 and Biological Analysis of Water and
Wastewater , AM 302, Millipore Corp., 1974, pp. 4-6.
Samples can be taken directly from wells with a sterile bottle in a weighted
frame which can be lowered below the water surface and opened below surface.
Samples can also be obtained by means of various pumping devices, as described
7-4
-------
f,
•I!
f: !
510
m
ch— chain which anchon upper valve to upper interior guide
«Jh— rubber drain tube.
dt— bras* drain lube.
«— interior guide fastened to inner surface of umplcr
h— rubber lube.
j— jaw of release.
js— j«w spring.
I* — lower valve.
m — messenger.
o — opening interior of drain lube.
P— pinch cocV .
""* °n hon'"ntl1 Pin- «« "d of »«cl> Hi. into groove on central rod
"'""' f "^ "' Openlil" in "°°v -
irfi*. i
ofeinii
uv— upper valve.
£f/'— View of complete samp'tr with »aI»-« open.
««*/— Another type of construction of upper valve and tripping device
/om «jAr-Anoir,er t)F- of eon«rue:,on oflo^er vj|.e and driin tube. '
FIG. 4 Di.gr.ai Sho.jnt Strurtur»l rc.ruro of Modifiri Kfmrvfrf r Simpler."
C. S. Welch, LlmnotoficotMrthoib, p 200. Fig S9
FIGURE 7-2
7-5
-------
previously. The same pumping schedule should be observed as for non-sterile
samples. Sample volumes of approximately 250 ml. are usually satisfactory
for bacteriological testing.
Sampling and preservation of samples are addressed in the 1973 Annual Book
of ASTM Standards. Part 23, Water; Atmospheric Analysis, pp. 72-75, Standard
Methods of Sampling Homogeneous Industrial Waste Water; and pp. 76-91, Stan-
dard Methods of Sampling Water.
7.2.2 RECORDS
Adequate records should be maintained on each sample that is taken. Record
information should include:
Sample description: Type (ground water, surface water) volume.
Sample source: Well number, location.
Sampler's Identity: Chain of evidence should be maintained; each time
transfer of a sample occurs a record including signatures of parties
involved in transfer should be made. This procedure can have legal
significance .
Time and date of sampling.
Significant weather conditions.
Sample laboratory number.
Pertinent well data: Depth, depth to water surface, pumping schedule
and method.
Sampling method: Vacuum, Kemmerer, pressure.
Preservatives,if any: Type and number - i.e. HaOH for cyanide, H3PO
and CuSO^ for phenols, etc.
7-6
-------
Sample containers: Type, size and number - i.e. - three (3) liter
glass stoppered bottles, one (1) one gallon screw-cap bottle, etc.
Reason for sampling: Initial sampling of new landfill; annual sampling,
quarterly sampling, special problem sampling, in conjunction with con-
taminant discovered in nearby domestic well.
Appearance of sample: Color, turbidity, sediment, oil on surface.
Any other information which appears to be significant: i.e. sampled
in conjunction with state, county, local regulatory authorities.
Sampled for specific conductance value only.
Sampled for key indicator analysis.
Sampled for extended analysis.
Re-sampled following engineering corrective action.
Name and location of laboratory performing analyses.
Sample temperature upon sampling.
Thermal preservation: i.e. - transportation in ice chest.
Analytical determinations, if any, preformed in the field at the time
of sampling and results obtained, analysts identity and affiliation.
7.3 SAMPLE CONTAINERS
For most samples and analytical parameters, either glass or plastic containers
are satisfactory. Some exceptions are encountered, such as the use of
plastic for silica determinations and glass for phenols, or oil and grease
determination. Containers should be kept full until samples are analyzed,
in order to maintain anaerobic conditions.
As a general guide in choosing a container for a sample, the ideal material
of construction should be non-reactive with the sample and especially, the
7-7
-------
particular analytical parameter to be tested. Table 2 lists the recommended
containers for various analyses.
Cleanliness of containers is of utmost importance. An effective procedure
for cleaning containers is to wash sequentially with a detergent, tap water
rinse, nitric acid rinse, tap water rinse, hydrochloric acid rinse, tap
water rinse and finally, deionized or distilled water. In addition, the
containers should be rinsed several times with the sample at the time of
sampling.
7.4 PRESERVATION OF SAMPLES AND SAMPLE VOLUME REQUIREMENTS.
The following excerpt from Methods for Chemical Analysis of Water and Waste.
EPA-625/6-74-003, pp. vi-xii, is a useful guide for sample preservation,
sample volume requirements and sample containers.
Additional useful information relative to preservation of polluted waters,
wastewaters, etc., is available in Standard Methods. 13th Ed., 1971, pp. 368-
369.
Additionally, Standard Methods provides a very useful "Sampling and Storage"
section for many of the analytical methods offered.
7.5 PRESERVATION OF SAMPLES IN THE FIELD
Samples should be preserved at low temperatures during transport to the
laboratory for analysis. A convenient method is to use an insulated cooler
containing ice so that a temperature of 0 to 10°C is maintained.
If possible, appropriate chemical preservation should be performed in the
7-8
-------
field for various analytical parameters at the time of sampling. In this
case, separate bottles and chemical preservatives are required for particular
parameters. As an example, for the extended analyses group in Chapter 6,
proper preservation techniques would require splitting the sample into as
many as approximately ten (10) bottles. Thus, one can see that sampling
a large number of wells for several analyses can become a cumbersome procedure
in the field for this reason.
Regardless of the method of preservation, analyses should be performed as
soon as is practicably possible after sampling.
7-9
-------
SAMPLE PRESERVATION
Complete and unequivocal preservation of samples, cither domestic sewage, industrial
wastes, or natural waters, is a practical impossibility. Regardless of the nature of the sample,
complete stability for every constituent can never be achieved. At best, preservation
techniques can only retard the chemical and biological changes that inevitably continue
after the sample is removed from the parent source. The changes that take place in a sample
are either chemical or biological. In the former case, certain changes occur in the chemical
structure of the constituents that are a function of physical conditions. Metal cations may
precipitate as hydroxides or form complexes with other constituents;cations or anions may
change valence states under certain reducing or oxidizing conditions; other constituents may
dissolve or volatilize with the passage of time. Metal cations may also adsorb onto surfaces
(glass, plastic, quartz, etc.). such as, iron and lead. Biological changes taking place in a
sample may change the valence of an element or a radical to a different valence. Soluble
constituents may be converted to organically bound materials in cell structures, or cell lysis
may result in release of cellular material into solution. The well known nitrogen and
phosphorus cycles are examples of biological influence on sample composition.
Methods of preservation are relatively limited and are intended generally to (1) retard
biological action, (2) retard hydrolysis of chemical compounds and complexes and (3)
reduce volatility of constituents.
Preservation methods are generally limited to pH control, chemical addition, refrigeration,
and freezing. Table 1 shows the various preservatives that maybe used to retard changes in
samples.
VI
-------
Preservative
HgCl,
Acid(HNO3)
Acid(H2SO4)
Alkali (NaOH)
Refrigeration
TABLE 1
Action
Bacterial Inhibitor
Metals solvent, pre-
vents precipitation
Bacterial Inhibitor
Salt formation with
organic bases
Salt formation with
volatile compounds
Bacterial Inhibitor
Applicable to:
Nitrogen forms,
Phosphorus forms
Metals
Organic samples
(COD, oil & grease
organic carbon)
Ammonia, amines
Cyanides, organic
acids
Acidity-alkalinity,
organic materials,
BOD, color, odor,
organic P, organic
N» carbon, etc.,
biological organism
(coliform, etc.)
In summary, refrigeration at temperatures near freezing or below is the best preservation
technique available, but it is not applicable to all types of samples.
The recommended choice of preservatives for various constituents is given in Table 1. These
choices are based on the accompanying references and on information supolied by various
Regional Analytical Quality Control Coordinators.
vii
-------
TABLE 2
RECOMMENDATION FOR SAMPLING AND PRESERVATION
OF SAMPLES ACCORDING TO MEASUREMENT (I)
Measurement
I
Acidity
i
Alkalinity
*
Arsenic
BOD
Bromide
COD
Chloride
Chlorine Req.
Color
Cyanides
Vol.
Req.
(ml)
100
100
100
1000
100
- 50
50
50
50
500
Container
P, G«>
P,G
P,G
P,G
P,G
P,G
P,G
P,G
P,G
P,G
Preservative
Cool, 4°C
Cool, 4°C •
HNO3 to pH <2
Cool, 4°C
Cool, 4°C
H2SO< topH<2
None Req.
Cool, 4°C
Cool, 4° C
Cool, 4°C
Holding
Time(6)
24 Hrs.
24 Hrs.
6Mos,
6 Hrs.<3)
24 Hrs.
7 Days
7 Days
24 His.
24 Hrs.
24 Hrs.
NaOHtopH 12
Dissolved Oxygen
Probe
• Winkler
300 G only Det. on site
300 G only Fi.\ on site
No Holding
No Holding
vni
-------
TABLE 2 (Continued)
Vol.
Req.
Measurement (ml) Container Preservative
Fluoride 300 P, G Cool,4°C
Hardness 100 P, G Cool,4°C
Iodide 100 P, G Cool,4°C
MBAS 250 P, G Cool, 4° C
Metals
Dissolved 200 P, G Filter on site
-HN03 topH<2
Suspended -'* Filter on site
Total 100 HNO3topH<2
Mercury
Dissolved 100 P, G Filter
HNO3 to pK <2
Total 100 P, G HNO3 to pH <2
Holding
Time(6)
7 Days
7 Days
24 Mrs.
24Hrs.
6 Mos.
/
6 Mos.
6 Mos.
-
38 Days
(Glass)
13 Days
(Hard
Plastic)
38 Days
(Glass)
1 3 Days
(Hard
Plastic)
IX
-------
TABLE 2 (Continued)
Vol.
Req.
Measurement (ml)
Nitrogen
Ammonia 400
Kjeldahl 500
Nitrate 100
Nitrite 50
NTA ... SO
Oil & Grease 1000
Organic Carbon 25
pH 25
Phenolics 500
Phosphorus
Ortho-
.phosphate, 50
Dissolved
Container Preservative
P, G Cool, 4°C
H2SO4 topH<2
P, G Cool, 4°C
HiSO4 topH<2
P, G Cool, 4°C
H,SO4 topH<2
P, G Cool, 4°C
P, G Cool. 4°C
G only Cool, 4°C
H,S04 topH<2
P, G Cool, 4°C '
• H2 SO« to pH <2
P, G Cool, 4°C
DeL on site
G only Cool, 4°C
H3P04 iopH<4
1.0gCuS04/l
P, G Filter on site
Cool. 4°C
Holding
Time(6)
24Hrs.<«>
24Hrs/«>
24Hrs.<4>
24Hrs. <«)
24Hrs.
24 Mrs.
24Hrs.
6Hrs.<3>
24Hrs.
24Hrs.(4>
-------
TABLE 2 (Continued)
Measurement
Hydrolyzable
Total
Total,
Dissolved
Residue
Filterable
Non-
Filterable
Total
Volatile
Vol.
Req.
(ml)
SO
50
SO
100
100
100
100
Container Preservative
P, G Cool, 4°C
HjSO4 topH<2
P, G . Cool, 4°C
P, G Filter on site
Cool, 4°C
P, G Cool, 4°C
P, G Cool, 4°C
P, G Cool, 4°C
P, G Cool, 4°C
Holding
Time(6)
24Hrs.<")
24Hrs. C«>
24 Hrs.<4>
7 Days
7 Days
7Days
7 Daya
Settleable Matter 1000 P, G
None Req.
24Hrs.
Selenium
Silica
Specific
Conductance
Sulfate
50 P, G HNO3 to pH <2 6 Mos.
50 Ponly Cool, 4° C
100 P,G
50 P, G
Coo!, 4°C
Cool, 4°C
xi
7 Days
24Hrs.
7 Days
-------
TABLE 2 (Continued)
Measurement
Vol.
Req.
(ml)
Container Preservative
Holding
Time(6)
Sulfide
50 P,G
2 ml zinc
acetate
24Hrs.
Sulflte
'Temperature
50 P,G
1000 P,G
Cool, 4°C
Det. on site
24Hrs.
No Holding
Threshold
Odor
Turbidity
200 G only Cool, 4°C
100 P.G
Cool, 4°C
24Hrs.
7 Days
1. More specific instructions for preservation and sampling are found with each procedure
as detailed in 'this manual. A general discussion on sampling water and industrial
wastewater may be found in ASTM, Part 23, p. 72-91 (1973).
2. Plastic or Glass
3. If samples cannot be returned to the laboratory in less than 6 hours and holding time
exceeds this limit, the final reported data should indicate the actual holding time.
4. Mercuric chloride may be used as an alternate preservative at a concentration of 40
mg/1, especially if a longer holding time is required. However, the use of mercuric
chloride is discouraged whenever possible.
5. If the sample is stabilized by cooling, it should be warmed to 25°C for reading, or
temperature correction made and results reported at 25°C.
6. It has been shown that samples properly preserved may be held for extended periods
beyond the recommended holding time.
Xll
-------
CHAPTER 8
ANALYTICAL METHODS
8.1 INTRODUCTION
Reliable, cost effective analytical methods must be selected and applied in
order to successfully carry on Basic Indicator, and Extended Analysis programs.
The parameters of interest in the analytical characterizations of leachate are
usually physical, chemical and biological. Normally, the desired information
is quantitative rather than qualitative, although qualitative data may be
required at times for special problems. For purposes of this Manual, consider-
ation will be given only to the quantitative aspect of the analytical data.
As stated previously, "Leachate represents an extremely complex
system containing soluble, insoluble, organic, inorganic, ionic, nonionic and
bacteriological constituents in an aqueous medium. Actual types, numbers and
levels of constituents are widely variable...."
When dealing with a complex material of variable composition, such as
leachate, it is recognized that there is a serious potential for numerous
interferences in the determination of a given parameter.
The physical measurements, such as specific conductance and pH, are not
normally subject to appreciable interference,but many of the chemical and
biological determinations are readily affected by matrix interferences.
8-1
-------
When an analyst wishes to perform a quantitative determination on a particular
parameter, he must decide which analytical method will be used. There is
usually a choice among several standard methods which can be applied to a
given determination. Among the many factors which must be considered in the
choice of an analytical method are the following: sensitivity, precision and
accuracy required, nature of the matrix and its effect upon the determination
(interferences), available equipment, manpower and instrumentation, level of
expertise of the analyst, number of samples to be analyzed, turn-around time,
history and available information regarding the sample, reason for performing
the analysis, how the analytical data will be offered other parameters, if
any, to be determined on the sample, importance of cost factors. When all
pertinent considerations of this nature have been carefully weighed the
decision is then made to apply a particular standard method to the problem.
There are several literature sources of standard analytical methods which can
be applied, either directly or with modification, to the analysis of leachate
samples. There are three references which are in wide use for this purpose,
namely:
1. Standard Methods for the Examination of Water and Wastewater. 13th Ed.
APHA, 1971
2. Manual of Methods for Chemical Analysis of Water and Wastes, U. S.
Environmental Protection Agency, 1974
3. 1973 Annual Book of ASTM Standards. Part 23, Water; Atmospheric
Analysis
Some comments are made relative to the analysis of polluted waters and other
similar samples in Standard Methods for the Examination of Water and Wastewater.
P. 367. These comments, following, are appropriate to review at this point.
"These procedures described in Part 200 of this manual are intended for the
8-2
-------
physical and chemical examination of wastewaters of both domestic and indus-
trial origin, treatment plant effluents, polluted waters, sludges and bottom
sediments. An effort has been made to present methods which apply as generally
as possible and to indicate modifications which are required for samples o£
unusual composition, such as certain industrial wastes. However, because of
the wide variety of industrial wastes, the procedures given here cannot cover
all possibilities and may not be suitable for all wastes and combination of
wastes. Hence, some modification of a procedure may be necessary in specific
instances. Whenever a procedure is modified, the nature of the modification
must be plainly stated in the report of results. The procedures which are
indicated as being intended for the examination of sludges and bottom sediments
may not apply without modification to chemical sludges or slurries."
In this same vein, the following comments are made in Handbook for Analytical
Quality Control in Water and Wastewater Laboratories, U.S.E.P.A., 1973, P 1-3.
"Regardless of the analytical method used in the laboratory, the specific
methodology should be carefully documented. In some water pollution reports
it is customary to state that Standard Methods have been used throughout.
Close examination indicates, however, that this is not strictly true. In many
laboratories, the standard method has been modified because of recent research
or personal preferences of the laboratory staff. In other cases, the standard
method has been replaced with a better one. Statements concerning the methods
used in arriving at laboratory data should be clearly and honestly stated.
The methods used should be adequately referenced and the procedures applied
exactly as directed.
Knowing the specific method which has been used, the reviewer can apply the
associated precision and accuracy of the method when interpreting the labora-
tory results. If the analytical methodology is in doubt, the data user may
honestly inquire as to the reliability of the result he is to interpret.
8-3
-------
The advantages of strict adherence to accepted methods should not stifle
investigations leading to improvements in analytical procedures. In spite
of the value of accepted and documented methods, occasions do arise when a
procedure must be modified to eliminate unusual interference, or to yield
increased sensitivity. When modification is necessary, the revision should
be carefully worked out to accomplish the desired result. It is advisable to
assemble data using both the regular and the modified procedure to show the
superiority of the latter. This useful information can be brought to the
attention of the individuals and groups responsible for methods standard-
ization. For maximum benefit, the modified procedure should be rewritten
in the standard format so that the substituted procedure may be used through-
out the laboratory for routine examination of samples. Responsibility for
the use of a non-standard procedure rests with the analyst and his supervisor,
since such use represents a departure from accepted practice."
8.2 Alternate Analytical Methods
8.2.1 Method Comparability
Relative to the use of alternate analytical methods for the National Pollution
Discharge Elimination System, the EPA has published guidelines in the Federal
Register, October 16, 1973, as follows:
"Typical Comparability Testing Procedure.
This procedure is designed to provide data on the comparability(equivalency)
of two dissimilar analytical methods for measurement of the same property or
constituent.
In regarding the comparison, one method is assumed to be satisfactory (standard)
and the second or alternate method is compared for equivalency.
To provide sufficient data to apply statistical measurements of significance,
the following determinations are required:
8-4
-------
1. Using an effluent sample representative of normal operating
processes, well mixed between aliquot withdrawal, run seven
replicate determinations by each method.
Report values in the following manner:
TABLE 1
Effluent Sample Representative of Normal Operating
Conditions.
Aliquot Standard Method* Alternate Method*
List 1 through 7
*Cite method reference
2. If variations occur in the concentration of the measured
constituent in the plant effluent, report the above testing
on two more samples, one collected at f.he highest level of
constituent normally encountered in the waste samples examined
by the laboratory and one having a concentration at or near
the lowest level usually examined. Report values in the
following manner:
TABLE 2
Effluent Samples of Varying Composition
Aliquot Low Level High Level
List 1 through 7
3. Using the sample from 1, add a small volume of standard solution
sufficient to double the concentration. Run 7 replicate determina-
tions by each method. Report values as Table 3:
Effluent Samples Plus Standard Solution, in the same way as Table 1. Cite
source and amount of standard solution; it should be proportioned to the
8-5
-------
to the original concentration. The ahove procedure must be followed on each
outfall for which a permit is issued, unless it can be shown that the outfalls
in question are comparable."
A comparability of that procedure for analytical methods used on landfill leachate
samples can be modelled after the above-cited EPA procedure. Samples, instead
of representing plant effluents, will represent potentially leachate-enriched
ground and/or surface waters. The results of the standard and alternate methods
should be compared for statistically significant differences. If the alternate
method proves to be equal to or better than the standard method, it should be
considered an acceptable analytical method for the determination of the particular
parameter in the leachate sample.
8.2.2 Other Analytical Methods
A considerable amount of valuable pertinent information on analytical method-
ology and data is available in Standard Methods for the Examination of Water
and Wastewater. 13th Edition. 1971. Several sections of this work are reprinted
here to be used as a guide in the analysis of leachate samples. The particular
subjects of interest which are treated are:
1. Other (instrumental) methods of analysis, including Atomic
Absorption Spectroscopy, FlamePhotometry, Emission Spectroscopy,
Polarography, Potentiometric Tiliation, Specific Ion Electrodes
and Probes, Gas Chromotography and Automated Analytical Instrumentation.
(pp. 12-15)
2. Interferences and methods used for their elimination, (pp. 15-18)
3. Expression of Results, (pp. 18-20)
4. Siginficant Figures, (pp. 20-21)
8-6
-------
5. Precision and Accuracy. Statistical Approach, Standard Deviation,
Range, Rejection of Experimental Data, Presentation of Precision
and Accuracy Data, Quality Control. (pp. 22-25)
6. Graphical Representation of Data, Method of Least Squares. (pp. 25-27)
7. Self-Evaluation (Desirable Philosophy for the Analyst). (p. 27)
8. Methods Evaluation by the Committee on Standard Methods of the Water
Pollution Control Federation. (pp.369-370)
8-7
-------
M
ff. '. i
IM
«
an alkali, as is done in the direct nes-
slerization method for ammonia nitro-
gen. For samples of relatively coarse
turbidity, centrifuging may suffice. In
some instances, glass fiber niters, filter
paper or sintered-glass filters of fine
porosity will serve the purpose. For
very small particle sizes, the more re-
cently developed cellulose acetate mem-
brane filters may provide the required
retentivcness. Used with discretion,
each of these methods will yield satis-
factory results in a suitable situation.
However, it must be emphasized that
no single universally ideal method of
turbidity removal is available. More-
over, the analyst should be perpetually
alert to adsorption losses possible with
any flocculating or filtering procedure
and an attendant alteration in the sam-
ple filtrate.
8. Other Methods of Analysis
The use of an instrumental method
of analysis not specifically described in
procedures in this manual is permis-
sible, provided that the results so ob-
tained are checked periodically, either
against a standard method described in
this manual or against a standard sam-
ple of undisputed composition. Iden-
tification of any such instrumental
method used must be included in the
laboratory report along with the analyt-
ical results.
a. Atomic absorption spectroscopy:
Atomic absorption spectrophotometry
has been applied to the determination
of a growing number of metals in drink-
ing water without the need for prior
concentration or extensive sample pre-
treatment. The use of organic solvents
coupled with oxjacetylene, oxyhydro-
gen or nitrous oxide-acetylene flames
enables the determination of metals
GENERAL INTRODUCTION (000)
which form refractory oxides. This
manual presents atomic absorption
methods for many metals. Although
not described in the text, calcium,
lithium, potassium, sodium and stron-
tium can also be determined readily by
the atomic absorption approach.
b. Flame photometry: Flame pho-
tometry is used for the determination of
sodium, potassium, lithium and stron-
tium. To some extent it is also useful
for the determination of calcium and
other ions.
c. Emission spectroscopy: Arc-spark
emission spectroscopy is becoming an
important analytical tool for water
analysis and is proving valuable both
for trace analysis and for certain de-
terminations not easily made by any
other method. Considerable specialized
training and experience with this tech-
nic are required to obtain satisfactory
results, and frequently it is practical
to obtain only semiquantitative results
from such methods in water analysis. It
should be noted that an arc-spark emis-
sion spectrograph is relatively expen-
sive when used exclusively for routine
water testing, but its purchase is jus-
tified if it can be used as a general
laboratory analytical instrument.
Among the advantages of aic-spark
spectrographic analyses are: (1) the
minute size of sample required; (2)
elimination of the necessity for bringing
solids, such as precipitates and corro-
sion products, into solution; (3) de-
tection of all determinate elements
present in a sample, whether specifically
looked for or not; and (4) their unex-
celled sensitivity for some elements
Among the disadvantages of spectro-
graphic analyses arc: (1) the hich cost
of first-class equipment; (2) the need
for special training and experience;
(3) the possible occurrence of scveio
-------
TECHNIC/Other Method* of Analyiij
interferences which must be taken into
account if reasonable accuracy is to be
achieved; and (4) the inability to dis-
tinguish between different valence states
of an element, as, for instance, between
chromic and chromate or ferric and
ferrous.
Silver is the only clement for which
a spectrographic method is described in
this manual. The following can also be
determined spectrographically: alumi-
num, barium, boron, chromium, cop-
per, iron, lead, lithium, magnesium,
manganese, nickel, silicon, strontium
and zinc. Among the elements for
which there is no standard method in
this manual but which are dcterminable
by arc-spark spectrography are cobalt,
molybdenum, tin, titanium, vanadium
and a number of others.1-2
d. Polarography: Polarography is
suggested for scanning industrial wastes
for various metal ions, especially where
the possible interferences in the precise
colorimetric procedures are unknown.
The older polarographic method for
dissolved oxygen also remains from the
past.
Recent developments in polarogra-
phy include the introduction of pulse
polarographs with dual synchronized
electrodes capable of differential deriva-
tive output. Operation in the pulse
mode permits determination of seven
or more metals on a single portion of
the sample after ashing with nitric acid.
If a 100-ml portion of the sample is
ashed, determinations may be made in
the low microgram-per-liter range.
A method closely allied to polarogra-
phy is amperometric titration, which is
suitable for the determination of re-
sidual chlorine and other iodometric
methods by titrimetry.
e. Potentiomelric titration: Growing
in acceptance for titrimetric work are
II
electrical instruments called titrimctcrs,
or electrotitrators. If used discreetly
with an understanding of their limita-
tions, these instruments can bs applied
to many of the titrimetric determina-
tions described, including those for
acidity and the alkalinities. In addition,
titrimetric precipitation reactions such
as those for chloride, as well as titri-
metric procedures based on complexo-
metric and oxidation-reduction reac-
tions, can be performed with these
instruments. To be suitable for these
extensive applications, an instrument
must be equipped with all the necessary
special electrodes. Some recent electro-
titrator models embody automatic fea-
tures by which a titration is self-execut-
ing after the preliminary settings are
made. In order to avoid spurious read-
ings, the analyst is urged to check
instrument operation against represen-
tative known samples in the same con-
centration range as the water under
examination.
/. Specific ion electrodes and probes:
The past decade has witnessed the ad-
vent of specific ion electrodes and
probes for the rapid estimation of cer-
tain constituents in water. These
electrodes function best in conjunction
with the concurrently developed ex-
panded-scale pH meters. For the most
part, the new electrodes operate on the
ion-exchange principle. The specific
ion electrodes available at this time are
designed for the measurement of cal-
cium, divalent copper, divalent hard-
ness, potassium, sodium, total mono-
valent and total divalent cations, and
bromide, chloride, cyanide, fluoride.
iodide, nitrate, perchlorate and sulfide
anions among others. Additional spe-
cific ion electrodes can doubtless be
anticipated in the future.
These devices are subject to varying
8-9
-------
14
degrees of interference from other ions
in the sample and must still receive the
thorough study that would warrant
their adoption as tentative and standard
methods. Nonetheless, their value for
monitoring activities is readily ap-
parent. To remove all doubt of varia-
tions in reliability, each electrode should
be checked in the presence of inter-
ferences as well as 'the ion for which it
is intended. This manual details the
electrode method for fluoride after a
collaborative study established its
credibility in the presence of common
interferences (Section 121).
The commercial dissolved oxygen
probes vary considerably in their de-
pendability and maintenance require-
ments. Despite these shortcomings,
they have bsen applied to the monitor-
ing of dissolved oxygen levels in a
variety of waters and wastewaters.
Most probes embody an electrode
covered by a thin layer of electrolyte
held in place by an oxygen-permeable
membrane. The oxygen in solution
diffuses through the membrane and
electrolyte layer to react at the elec-
trode, inducing a current which is pro-
portional to the activity (and con-
centration) of the dissolved oxygen.
Satisfactory dissolved-oxygen electrodes
are also available without a membrane.
In either case, the face of the dissolved
oxygen sensor should be kept well
•agitated, and temperature compensa-
tion should be provided, in order to in-
sure acceptable results in the laboratory
or monitoring application.
g. Gas chromatography: Consider-
able work is under way in the develop-
ment of gas chromatographic methods
suitable for water and wastewater anal-
ysis. Two such methods appear in
this manual: one for the determination
GENERAL INTRODUCTION (OCO)
of chlorinated hydrocarbon pesticides.
in drinking water; the second for the
determination of the components in
sludge digester gas. Investigations re-
veal that gas chromatography may also
be useful for the determination of
phenols. The skill of the operator and
the expense entailed in its purchase will
probably limit use of this specialized
instrumentation to the larger organiza-
tion which can afford the sizable finan-
cial outlay involved.
h. Automated analytical instrumen-
tation: Automated analytical instru-
ments are now available and in use to
run individual samples at rates of 10 to
60 samples per hour. The same instru-
ments can be modified to perform
analyses for two to twelve constituents
simultaneously from one sample. The
instruments are composed of a group
of interchangeable modules joined to-
gether in series by a tubing system.
Each module performs the individual
operations of filtering, heating, digest-
ing, time delay, color sensing, etc., that
the procedure requires.
The read-out system employs sensing
elements with indicators, alarms and/or
recorders. For monitoring applications,
automatic standardization-compensa-
tion, electrical and chemical, is done by
a self-adjusting recorder when known
chemical standards are sent periodically
through the same analytical train. Such
instrument systems are presently avail-
able.
Appropriate methodology is supplied
by the manufacturer for many of the
common constituents of water and
waslewatcr. Some methods arc based
on procedures described in this manual,
while other.":-originate from the manu-
facturer's adaptation of published re-
search. Since a number of methods of
8-10
-------
HNtC/lnl«rfer«ncM
varying reliability may be available for
a single constituent of water and waste-
water, a critical appraisal of the method
adopted is obviously mandatory.
Automated methodology is suscepti-
ble to the same interferences as the
original method from which it derives.
For this reason, new methods devel-
oped for automated analysis must be
subjected to the exacting tests for ac-
curacy and freedom from adverse
response already met by the accepted
standard methods.
Off color and turbidity produced
during the course of an analysts will be
visible to an analyst manually perform-
ing a given determination, and the re-
sult will be properly discarded. Such
abnormal effects caused by unsuspected
interferences might escape notice in an
automated analysis. Calibration of the
instrument system at least once each
day with standards containing inter-
'ercnces of known concentration could
^elp to expose such difficulties. Routine
practice is to check instrument action
and guard against questionable results
by the insertion of standards and
blanks at regular intervals—perhaps
after every 10 samples in the train.
Another important precaution is proper
sample identification by arrangement
into convenient groups.
In brief, a fair degree of operator
skill and knowledge, together with
adequately detailed instructions, is re-
quired for successful automated anal-
ysis.
/. Other newer methods of analysis:
Instrumentation and new methods of
analysis are always under development.
The analyst will find it to his advantage
to keep abreast of current progress.
Reviews of each branch of analytical
IS
chemistry are published regularly in
the periodical, Analytical Chemistry.
9. Interferences
Many analytical procedures are sub-
ject to interference from substances
which may be present in the sample.
The more common and obvious inter-
ferences are known, and information
about them has been given in the de-
tails of individual procedures. It is in-
evitable that the analyst will encounter
interferences about which he is not
forewarned. Such occurrences are un-
avoidable because of the diverse nature
of waters and particularly of waste-
waters. Therefore, the analyst must be
alert to the fact that hitherto untested
ions, new treatment compounds—espe-
cially complexing agents—and new
industrial wastes constitute an eve.--
present threat to the accuracy of cheni-
ical analyses. He must be on his guard
at all times to detect the occurrence of
such interferences.
Any sudden change in the apparent
composition of a supply which has been
rather constant, any off color observed
in a colorimetric test or during a titra-
tion, any unexpected turbidity, odor or
other laboratory finding is cause for
suspicion. Such a change may be due
to a normal variation in the relative
concentrations of the usual constit-
uents, but it may be caused by the
introduction of an unforeseen interfer-
ing substance.
A few substances—such as chlorine,
chlorine dioxide, alum, iron salts, sili-
cates, copper sulfate, ammonium sul-
fate and polyphosphates—are so widely
used in water treatment that they de-
serve special mention as possible causes
of interference. Of these, chlorine is
8-11
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16
probably the worst offender, in that it
bleaches or alters the colors of many of
the sensitive organic reagents which
serve as titration indicators and as color
developers for photometric methods.
Among the methods which have proved
effective in removing chlorine residuals
are: the addition of minimal amounts
of sulfite, thiosulfate or arsenite; ex-
posure to sunlight or an artificial ultra-
violet source; and prolonged storage.
Whenever interference is encountered
or suspected, and no specific recom-
mendations are found in this manual
for overcoming it, the analyst must en-
deavor to determine what tecbnic, if
any, suffices to eliminate the inter-
ference without adversely affecting the
analysis itself. If two or more choices
of procedure are offered, often one pro-
cedure will be less affected than an-
other by the presence of the intcrferin°
substance. If different procedures yield
considerably different results, it is likely
that interference is present. Some in-
terferences become less severe upon di-
lution, or upon use of smaller aliquots;
any tendency of the results to increase
or decrease in a consistent manner with
dilution indicates the likelihood of
interference effects.
a. Interference may cause the ana-
lytical results to be either too high or
too low, as a consequence of one of the
following processes:
1) An interfering substance may re-
act like the substance sought, and thus
produce a high result—for example,
bromide will respond to titration as
though it were chloride.
2) An interfering substance may re-
act with the substance sought and thus
produce a low result—for example,
chloride will react with a portion of the
nitrate in the presence of the sulfuric
GENERAL INTRODUCTION (000)
acid, using the phcnoldisulfonic acid
method.
3) An interfering substance may
combine with the analytical reagent and
thus prevent it from reacting with the
substance sought—for example, chlo-
rine will destroy many indicators and
color-developing reagents.
Nearly every interference will fit one
of these classes. For example, in a
photometric method, turbidity may be
considered as a "substance" which acts
like the one being determined—that is
it reduces the transmission of light. Oc-'
casionally, two or more interfering sub-
stances, if present simultaneously, may
interact in a nonadditive fashion, either
canceling or enhancing one another's
effects.
b. The best way to minimize inter-
ference is to remove the interfering
substance or to render it innocuous by
one of these methods:
1) Either the substance sought or
the interfering substance may be re-
moved physically: For example, fluo-
ride and ammonia may be distilled off
leaving interferences behind; chloride
may be converted to silver chloride and
filtered off, leaving nitrate behind The
interferences may also be adsorbed on
an ion-exchange resin, a process de-
scribed more fully in Section 100B.
2) The pH may be adjusted so that
only the substance sought will react
3) The sample may be oxidized or
reduced to convert the interfering sub-
stance to a harmless form—for exam-
ple, chlorine may be reduced to chlo-
ride by adding thiosulfate.
4) The addition of a suitable agent
may complex the interfering substance
so that it is innocuous although still
present: For example, iron may be
complexed wilh pyrophosphate to prc-
-------
TECHNIC/Roeovory
vent it from interfering with the copper
determination; copper may be com-
plexcd with cyanide or sulfide to pre-
vent interference with the titrimetric
hardness determination.
5) A combination of the first four
technics may be used: For example,
phenols are distilled from an acid solu-
tion to prevent amines from distilling;
thiosulfate is used in the dithizone
method for zinc to prevent most of the
interfering metals from passing into the
carbon tetrachloride layer.
6) Color and turbidity may some-
times be destroyed by wet or dry ash-
ing, or may be removed by use of a
flocculating agent. Some types of tur-
bidity may be removed by filtration.
These procedures, however, introduce
the danger that the desired constituent
will also be removed.
c. If none of these technics is prac-
tical, several methods of compensation
can be used:
1) If the color or tuibidity initially
present in the sample interferes in a
photometric determination, it may be
possible to use photometric compensa-
tion. The technic is described in Sec-
tion OOOA.7 preceding.
2) The concentration of interfering
substances may be determined and then
identical amounts may be added to the
calibration standards. This involves
much labor.
3) If the interference does not con-
tinue to increase as the concentration
of interfering substance increases, but
tends to level off, then a large excess of
interfering substance may be added
routinely to all samples and to all stand-
ards. This is called "swamping." For
example, an excess of calcium is added
in the photometric magnesium deter-
mination.
17
4) The presence in the chemical re-
agents of the substance sought may be
accounted for by carrying out a blank
determination.
10. Recovery
A qualitative estimate of the presence
or absence of interfering substances in
a particular determination may be made
by means of a recovery procedure. Al-
though this method does not enable the
analyst to apply any correction factor
to the results of an analysis, it does give
him some basis for judging the applica-
bility of a particular method of analysis
to a particular sample. Furthermore,
it enables the analyst to obtain informa-
tion in this regard without an extensive
investigation to determine exactly
which substances can interfere in the
method used. It also does away with
the necessity of making separate deter-
minations on the sample for the inter-
fering substances themselves.
A recovery may be performed at the
same time as the determination itself.
Of course, recoveries would not be run
on a routine basis with samples \\hose
general composition is known or when
using a method whose applicability to
the sample is well established. Re-
covery methods are to be regarded as
tools to remove doubt about the ap-
plicability of a method to a sample.
In brief, the recovery procedure in-
volves applying the anal>lical method
to a reagent blank; to a series of known
standards covering the expected range
of concentration of the sample; to the
sample itself, in at least a duplicate run;
and to the recovery samples, prepared
by adding known quantities of the sub-
stance sought to separate portions of
the sample itself, each portion equal to
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18
the size of sample taken for the run.
The substance sought should be added
in sufficient quantity to overcome the
limits of error of the analytical method,
but without causing the total in the
sample to exceed the range of the
known standards used.
The results are first corrected by
subtracting the reagent blank from
each of the other determined values.
The resulting known standards are then
graphically represented. From this
graph, the amount of sought substance
in the sample alone is determined. This
value is then subtracted from each of
the determinations consisting of sam-
ple plus known added substance. The
resulting amount of substance divided
by the known amount originally added
and multiplied by 100 gives the per-
centage recovery.
The procedure outlined above may
be applied to colorimetric or instru-
mental methods of analysis. It may
also be applied in a more simple form
to titrimetric, gravimetric and other
types of analyses.
Rigid rules concerning the percentage
recoveries required for acceptance of
GENERAL INTRODUCTION (000)
results of analyses for a given sample
and method cannot be stipulated. Re-
coveries of substances in the range of
the sensitivity of the method may, of
course, be very high or very low and
approach a value nearer to 100% re-
covery as the error of the method be-
comes small with respect to the mag-
nitude of the amount of substance
added. In general, intricate and exact-
ing procedures for trace substances
which have inherent errors due to their
complexity may give recoveries that
would be considered very poor and
yet, from the practical viewpoint of
usefulness of the result, may be quite
acceptable. Poor results may reflect
either interferences present in the sam-
ple or real inadequacy of the method of
analysis in the range in which it is
being used.
It must be stressed, however, that the
judicious use of recovery methods for
the evaluation of analytical procedures
and their applicability to particular
samples is an invaluable aid to the
analyst in both routine and research
investigations.
000 B. Expression of Results
1. Units
Analytical results should be expressed
in milligrams per liter (mg/1). As-
suming that 1 liter of water, sewage or
industrial waste weighs 1 kilogram,
milligrams per liter is equivalent to
parts per million.* Only the signifi-
cant figures (see Section OOOB.2 be-
low) should be recorded.
If the concentrations are generally
less than 1 mg/1, it may be more con-
venient to express the results in micro-
grams per liter (pg/1). This is equiv-
alent to parts per billion (ppb), where
billion is understood to be 109. If the
concentration is greater than 10,000
* It should be noted that, in water analy-
sis, "parts per million" is always understood
to imply a weight/weight ratio, even though
in practice a \olume may be measured in-
stead of a weight. By contrast, "percent"
may be either a volume /volume or a weight/
weight ratio.
-------
EXPRESSION OF RESULTS
mg/1, the results should be expressed in
percent, 1 % being equivalent to 10,000
mg/1.
In reporting analyses of stream pol-
lution or evaluating plant operation and
efficiencies, it is desirable to express the
results on a weighted basis, including
both the concentration and the volume
of flow in cubic feet per second (cfs)
or million gallons daily (mgd). These
weighted results may be expressed as
quantity units (QU) according to the
practice of the U.S. Public Health Ser-
vice; as pounds per 24 hr; or as popu-
lation equivalents based on biochem-
ical oxygen demand (BOD). Totals
of the weighted units may be converted
to the weighted average mg/1. The
8.34
0.17
19
various units are calculated as follows:
X( 1,000 cfs)
X (mgd)
lb/24 hr = (mg/1) X (mgd) x 8.34
lb/24 hr = (mg/1) X (cfs) X 5.39
Population equivalent
= (mg/1 5-day BOD) X (mgd) X
Table 000(1) presents the factors
which are useful for converting the con-
centrations of the common ions found
in water—from milligrams per liter to
milliequivalents per liter, and vice
versa. The term milliequivalent used
in this table represents 0.001 of an
equivalent weight. The equivalent
weight, in turn, is defined as the weight
of the ion (sum of the atomic weights
TABLE 000(1): CONVERSION FACTORS*
(Milligrams per Liter—Milliequivalents per Liter)
Ion (Cation)
Al*
BJ*
Ba'*
Ca"
Cr»
Cu"
Fe"
PC"
H*
K*
Li*
Mg"
Mn1*
Mn"
Na*
NH,*
Pb"
Sr"
Zn"
me/1 =
mg/lX
0.1112
0.2775
0.01456
0.04990
0.05770
0.03148
0.03581
0.05372
0.9921
0.02557
0.1441
0 08226
0.03640
0.07281
0.04350
0.05544
0.009653
0.022S3
0.03060
mg/l =
me/lx
8.994
3.604
68.67
20.04
17.33
31.77
27.92
18.62
1.008
39.10
6.939
12.16
27.47
13.73
22.99
18.04
103.6
43.81
32.69
Ion (Anion)
BOr
Br
cr
co,-
CrO.*~
F-
HCOa-
HPO.1-
H-PO.-
HS-
HSO,-
HSO.-
r
NO,-
NOr
OH-
POA
S"
SiOj-
SO,"
so.-
me/l =
mg/1 X
0.02336
0.01251
0.02821
0.03333
0.01724
0.05264
0.01639
0.02084
0.01031
0.03024
0.01233
0.01030
0.007S80
0.02174
0.01613
0.05880
0.03159
0.06238
0.02629
0.02498
0.02083
mg'l =
me'lx
42.81
79.91
35.45
30.00
58.00
19.00
61.02
47.99
96.99
33.07
81.07
97.07
126.9
46.01
62.00
17.01
31.66
16.03
38.04
40 03
48 03
• Factors are based on ion charge and not on redox reactions which may be possible for
certain of these ions. Cations and anions are listed separately in alphabetical order.
8-15
-------
PK^f^:1
OH
of the atoms making up the ion) di-
vided bv the number of charges nor-
mally associated with the parttcular
ion The factors for converting results
from mg/1 to me/l were computed by
dividing the ion charge by the weight of
the ion. Conversely, the factors for
converting results from me/1 to mg/1
were calculated by dividing the weight
of the ion by the ion charge. This table
is offered for the convenience of labora-
tories which report results in me/1 as
well as mg/1.
2. Significant Figures
To avoid ambiguity in reporting re-
sults or in presenting directions for a
procedure, it is the custom to use "sig-
nificant figures." All the digits in a
reported result are expected to be
known definitely, except for the last
digit, which may be in doubt. Such a
number is said to contain only signifi-
cant figures. If more than a single
doubtful disit is carried, the extra digit
or digits are not significant. K an
analytical result is reported as 75.&
mg/1" the analyst should be quite cer-
tain of the "75," but may be uncertain
as to whether the ".6" should be .5 or
7 or even .4 or .8, because of unavoid-
able uncertainty in the analytical pro-
cedure. If the standard deviation were
known from previous work to be ±2
mg/1, the analyst would have, or at
least should have, rounded off the re-
sult to "76 mg/1" before reporting it.
On the other hand, if the method were
so good that a result of "75.61 mg/1
could have been conscientiously re-
ported, then the analyst should not
have rounded it off to 75.6.
A report should present only such
figures as are justified by the accuracy
of the work. The all too common prac-
GENERAL INTRODUCTION (000)
tice of requiring that quantities listed
in a column have the same number of
figures to the right of the decimal point
is justified in bookkeeping, but not in
chemistry. . .
a. Rounding off: Rounding off is
accomplished by dropping the digits
which are not significant. If the digit
6, 7, 8 or 9 is dropped, then the pre-
ceding digit must be increased by one
unit; if the digit 0, 1. 2, 3 or 4 is
dropped, the preceding digit is not
altered. If the digit 5 is dropped, the
preceding digit is rounded off to the
nearest even number: thus 2.25 be-
comes 2.2, and 2.35 becomes 2.4.
b. Ambiguous zeros: The digit 0
may record a measured value of zero,
or it may serve merely as a spacer
to locate the decimal point. If the re-
sult of a sulfate determination is re-
ported as 420 mg/1, the recipient of the
report may be in doubt whether the
zero is significant or not, because the
zero cannot be deleted. If an analyst
calculates a total residue (total solids)
content of 1,146 mg/1, but realizes that
the 4 is somewhat doubtful and that
therefore the 6 has no significance, he
\vill round off the answer to 1,150 mg/1
and so report, but here, too, the recip-
ient of the report will not know whether
the zero is significant. Although the
number could be expressed as a power
of 10 (e.g., ll.SxlO3 or 1.15x10').
this form is not generally used, as it
would not be consistent with the nor-
mal expression of results and might also
be confusing. In most other cases.
there will be no doubt as to the sense in
which the digit 0 is used. It is obvious
that the zeros are significant in sucti
numbers as 104,40.08, and 0.0003. In
a number written as 5.000, it is under-
stood that all the zeros are significant.
or else the number could have been
-------
EXPRESSION OF RESULTS
rounded off to 5.00, 5.0, or 5, which-
ever was appropriate. Whenever the
zero is ambiguous, it is advisable to
accompany the result with an estimate
of its uncertainty.
Sometimes, significant zeros are
dropped without good cause. If a buret
is read as "23.60 ml," it should be so
recorded, and not as "23.6 ml." The
first number indicates that the analyst
took the trouble to estimate the second
decimal place; "23.6 ml" would indi-
cate that he read the buret rather care-
lessly.
c. The plus-or-minus (±) notation:
If a calculation yields as a result
"1,476 mg/1" with a standard deviation
estimated as ±40 mg/1, it should be
reported as 1,480 ±40 mg/1. But if
the standard deviation is estimated as
•*00 mg/1, the answer should be
nded off still further and reported
1,500+ 100 mg/1. By this device,
ambiguity is avoided and the recipient
of the report can tell that the zeros are
only spacers. Even if the problem of
ambiguous zeros is not present, show-
ing the standard deviation is helpful
in that it provides an estimate of re-
liability.
d. Calculations: As a practical op-
erating rule, the result of a calculation
in which several numbers are multiplied
or divided together should be rounded
off to as few significant figures as are
present in the factor with the fewest
significant figures. Suppose that the
following calculation must be made in
order to obtain the result of an analysis:
56 X 0.003462 X 43.22
1.684
21
A ten-place desk calculator yields an
answer of "4.975740996," but this
number must be rounded off to a mere
"5.0" because one of the measure-
ments, 56, which entered into the cal-
culation has only two significant figures.
It was a waste of time to measure the
other three factors to four significant
figures because the "56" is "the weak-
est link in the chain" and limits the
accuracy of the answer. If the other
factors were measured to only three,
instead of four, significant figures, the
answer would not suffer and the labor
would be less.
When adding or subtracting num-
bers, that number which has the fewest
decimal places, not necessarily the few-
est significant figures, puts the limit on
the number of places that may justifi-
ably be carried in the sum or difference.
Thus the sum
0.0072
12.02
4.0078
25.9
4,886
4,927.9350
must be rounded off to a mere "4,928,"
no decimals, because one of the ad-
dends, 4,886, has no decimal places.
Notice that another addend, 25.9, has
only three significant figures and yet it
does not set a limit to the number of
significant figures in the answer.
The preceding discussion is neces-
sarily oversimplified, and the reader is
referred to the bibliography for a more
detailed discussion.
l&' ••
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GENERAL INTRODUCTION (000)
000 C. Precision and Accuracy
' • - -Tjtf 1«
A clear distinction should be made
between the terms "precision" and "ac-
curacy" when applied to methods of
analysis. Precision refers to the re-
producibility of a method when re-
peated on a homogeneous sample under
controlled conditions, regardless of
whether or not the observed values are
widely displaced from the true value
as a result of systematic or constant
errors present throughout the measure-
ments. Precision can be expressed by
the standard deviation. Accuracy re-
fers to the agreement between the
amount of a component measured by
the test method and the amount actu-
ally present. Relative error expresses
the difference between the measured
and the actual amounts, as a percent-
age of the actual amount. A method
may have very high precision but re-
cover only a part of the element being
determined; or an analysis, although
precise, may be in error because of
poorly standardized solutions, inac-
curate dilution technics, inaccurate
balance weights, or improperly cali-
brated equipment. On the other hand,
a method ma\ be accurate but lack pre-
cision because of low instrument sensi-
tivity, variable rate of biologic activity,
or other factors beyond the control of
the analyst.
It is possible to determine both the
precision and the accuracy of a test
method by analyzing samples to which
known quantities of standard sub-
stances have been added. It is possible
to determine the precision, but not the
accuracy, of such methods as those for
suspended solids, BOD, and numerous
physical characteristics because of the
unavailability of standard substances
that can be added in known quantities
-9970S-
-9545R
! I
-2
-------
PRECISION & ACCURACY
about the mean is related to the stan-
dard deviation. For example, 68.27%
of the observations lie between x ± I a\
95.45%, between x ± 2 v\ and 99.70%,
between x ± 3 a. These limits do not
apply exactly for any finite sample from
a normal population; the agreement
with them may be expected to be better
as the number of observations, n, in-
creases.
b. Application of standard devia-
tion: If the standard deviation, «r, for
a particular analytical procedure has
been determined from a large number
of samples, and a set of n replicates on
a sample gives a mean result x, there is
a 95% chance that the true value of
the mean for this sample lies within
the values x±l.96a/\fn. This range
is known as the 95% confidence inter-
val. It provides an estimate of the reli-
ability of the mean, and may be used to
forecast the number of replicates
needed to secure suitable precision.
If the standard deviation is not known
and is estimated from a single small *
sample, or a few small samples, the
95% confidence interval of the mean
of n observations is given by the equa-
tion x ± to/^fn, where / has the fol-
lowing values:
23
c. Range (R): The difference be-
tween the smallest and largest of n ob-
servations is also closely related to the
standard deviation. When the distribu-
tion of errors is normal in form, the
range, R, of n observations exceeds the
standard deviation times a factor dn
only in 5% of the cases. Values for
the factor dn are:
2
3
4
5
10
oo
12.71
4.30
3.18
2.78
2.26
1.96
The use of / compensates for the ten-
dency of small samples to underesti-
mate the variability.
• A "small sample" in statistical discus-
sions means a small number of replicate
determinations, n, and docs not refer to the
quantity used for a determination.
2
3
4
277
3.32
3.63
3.86
4.03
As it is rather general practice to
run replicate analyses, use of these
limits is very convenient for detecting
faulty technic, large sampling errors,
or other assignable causes of variation.
d. Rejection of experimental data:
Quite often in a series of observations,
one or more of the results deviate
greatly from the mean, whereas the
other values are in close agreement
with the mean value. The problem
arises at this point as to rejection of the
disagreeing values. Theoretically, no re-
sults should be rejected, since the pres-
ence of disagreeing results shows faulty
technics and therefore casts doubt on
all the results. Of course the result of
any test in which a known error has
occurred is rejected immediately. For
methods for the rejection of other ex-
perimental data, standard texts on ana-
lytical chemistry or statistical mea-
surement should be consulted.
e. Presentation of precision and ac-
curacy data: The precision and accu-
racy data are presented in one of three
ways in this volume, depending on
when and how the information was
originally assembled.
8-19
a'-"'-
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24
In point of time, the oldest data are
given in the \vastcwatcr section and
present for the most part the precision
with which certain determinations can
be performed. These data first ap-
peared in the 10th Edition and survive
unchanged in the current volume. The
complex character of wastewater sam-
ples initially dictated this approach.
Beginning with the llth Edition, a
concerted effort was made to offer an
idea of the precision and accuracy
with which selected methods can bs
applied on a broad geographic basis in
examination of the relatively simpler
water samples. The manner of best
expressing the resulting data has re-
mained to this day a matter of relent-
less study. The llth and 12th Edi-
tions presented both precision and
accuracy in terms of mg/1. This prac-
tice is retained for the time being where
such data continue to be cited in this
manual. However, experience of the
past decade suggests that data can be
presented with greater brevity and
easier understanding in the form of a
percentage. By this system, the stan-
dard deviation is expressed as a per-
centage of the mean and is now termed
the relative standard deviation. It
measures the precision or reproducibil-
ity of a method, independent of the
known concentration of the sample
constituent. Similarly, the relative error
gives the difference between the mean
of a series of test results and the true
value, expressed as a percentage of the
true value. Thus, the relative error
represents the measure of the accuracy
of a method. The relative standard de-
viation and relative error are preferred
in quoting the precision and accuracy
of a method because they are indepen-
dent of the concentration.
/. Quality control: Quality control
GENERAL INTRODUCTION (000)
may be defined for the purpose of this
manual as a statistical system for moni-
toring the precision (variation), or rc-
producibility, of analytical procedures
in a given laboratory.
The control chart provides an impor-
tant tool for identifying the causes of
variation in the quality of a procedure.
Certain variations in chemical proce-
dures occur by chance, about which
little or nothing can be done. How-
ever, variations can also result from
"assignable causes" such as differences
in methods, reagents, equipment, and
the skill of persons performing the
tests. Chance variations behave in a
random manner and show no cycles,
runs, or similarly recognizable pattern.
If, on the other hand, the variations in
the data exhibit cycles, runs, or a defi-
nite pattern, at least one assignable
cause may be at work, and the con-
ditions producing the variations are
said to be "out of control."
Two basic types of control charts
have proved valuable. The jc-chart is
used to monitor the average of a pro-
cedure, while the 7?-chart is used to
monitor the variability of a procedure.
An x-chart discloses the variation in
the averages of a number of replica-
tions of a given procedure. It consists
of a central line, x, and upper and
lower control limits, which may range
from +lo- to +3o- and -lo- to -So- stan-
dard deviations from the center line.
(The values of x and the standard de-
viation are derived from past data.)
Figure 5 in Section 100C.1 illustrates
one application of control charts. As
long as the sample averages remain in-
side the control limits and show only
random variation within the limits, the
procedure is said to be "in control"
with respect to its central tendency. If
an average falls outside the control
-------
book on Statistical Techniques for Col-
laborative Tests offers valuable infor-
mation on collaborative tests.
2. Graphical Representation of Data
PRECISION & ACCURACY
limits, or if there is nonrandom varia-
tion within the limits, the process is said
to be "out of control" with respect to
its central tendency. Such a condition
should prompt an investigation into the
assignable cause or causes of the ex-
treme variation.
The same basic principles which ap-
ply to the I-chart also hold for the
/Z-chart, except that the J?-chart is a
plotting of the ranges of samples. It
reveals variations in the ranges of sam-
ples rather than variation in the aver-
ages of samples.
One of the most important factors in
a quality control program is an ade-
quate supply of a stable known control.
This control can be a large sample from
a natural source known to contain the
constituent of concern or a synthetic
sample prepared in the laboratory from
chemicals of the highest purity grade.
Once the test to be controlled has been
selected, 20 or more determinations
for the same constituent in the control
sample are made under routine daily
conditions. The values are then totaled
and the average value is obtained. The
standard deviation is calculated to as-
certain the range of allowable variation
that can be expected in routine work
for this particular constituent. If this
same sample is then treated as a rou-
tine daily control sample, it is possible
to determine by the use of a control
chart constructed from the original 20
determinations whether the daily assays
for this constituent are in or out of
control. When the control sample is
prepared from chemicals of the highest
purity, the probable accuracy of the
determination can also be estimated.
Duncan's volume on Quality Control
and Industrial Statistics describes the
I- and /?-charts in detail and their rel-
evance to quality control. Youden's
Graphical representation of data is
one of the simplest methods for show-
ing the influence of one variable on an-
other. Graphs are frequently desirable
and advantageous in colorimetric analy-
sis because they show any variation of
one variable with respect to the other
within specified limits.
a. General: Ordinary rectangular-
coordinate paper is satisfactory for
most purposes. Twenty lines per inch
is recommended. Semilogarithmic pa-
per is convenient when one of the co-
ordinates is to be the logarithm of an
observed variable.
The five rules listed by Worthing
and Geffner for choosing the coordi-
nate scales are useful. Although these
rules are not inflexible, they are satis-
factory. When doubt arises, common
sense should prevail. The rules are:
1) The independent and dependent
variables should be plotted on abscissa
and ordinate in a manner which can be
easily comprehended.
2) The scales should be chosen so
that the value of cither coordinate can
be found quickly and easily.
3) The curve should cover as much
of the graph paper as possible.
4) The scales should be chosen so
that the slope of the curve approaches
unity as nearly as possible.
5) Other things being equal, the
variables should be chosen to give a
plot which will be as nearly a straight
line as possible.
The title of a graph should adequately
describe what the plot is intended to
show. Legends should be presented on
8-21
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the graph to clarify possible ambigui-
ties. Complete information on the con-
ditions under which the data were ob-
tained should be included in the legend.
b. Method of least squares: If suf-
ficient points are available and the
functional relationship between the two
variables is well defined, a smooth
curve can be drawn through the points.
If the function is not well defined, as is
frequently the case when using experi-
mental data, the method of least
squares is used to fit a straight line to
the pattern.
Any straight line can be represented
by the equation x = my + b. The slope
of the line is represented by the con-
stant m and the slope intercept (on the
x axis) is represented by the constant
b. The method of least squares has
the advantage of giving a set of values
for these constants not dependent upon
the judgment of the investigator. Two
equations besides the one for a straight
line are involved in these calculations:
m =
nZ>-« - (Syr
n being the number of observations
(sets of x and y values) to be summed.
In order to compute the constants by
this method, it is first necessary to cal-
culate 2*, Sy, Sy2, and 5*y. These
operations are carried out to more
places than the number of significant
figures in the experimental data be-
cause the experimental values are as-
sumed to be exact for the purposes of
the calculations.
Example: Given the following data
to be graphed, find the best line to fit
the points:
GENERAL INTRODUCTION (000)
Absoibance
0.10
0.20
0.30
0.40
0.50
0.60
0.70
Solute
Concentration
mg/l
29.8
32.6
38.1
39.2
41.3
44.1
48.7
Let y equal the absorbance values
which are subject to error, and x the
accurately known concentration of
solute. The first step is to find the sum-
mations (2) of x, y, y2, and xy:
29.8
32.6
38.1
39.2
41.3
44.1
48.7
0.10
0.20
0.30
0.40
O.SO
0.60
0.70
0.01
0.04
0.09
0.16
0.25
0.36
0.49
2.98
6.52
11.43
15.68
20.65
26.46
34.09
2 = 273.8
2.80
1.40
117.81
The next step is to substitute the
summations in the equations for m and
b; ii = 7 as there are seven sets of x
and y values:
7 (117.81)-2.80(273.8)
7 (1.40) — (2.80)'
= 29.6
1.4 (273.8)-2.80 (117.81)
7 (1.40)-(2.80)* -27.27
To plot the line, three convenient
values of y are selected—say, 0, 0.20,
0.60—and corresponding values of x
are calculated:
jr. = 29.6(0) -f 27.27 = 27.27
JT, = 29.6(0.20) + 27.27 = 33.19
x, = 29.6(0.60) + 27 27 = 45.04
When the points representing these
values are plotted on the graph, they
will lie in a straight line (unless an er-
ror in calculation has been made),
which is the line of best fit for the
PREr
o
o
c
Fi
tf
a:
-------
'
PRECISION & ACCURACY
07
06
OS
| 04
I 0.3
02
0.1
0
— r
e Enpenmental Data
/
/
/
/
/
/
20
30 40
Solute Concentration - rog/l
Figure 2. Example of least-bquares method.
given data. The points representing
the latter are also plotted on the graph,
as in Figure 2.
3. Self-Evaluation (Desirable Philosophy
tor the Analyst)
A good analyst continually tempers
his confidence with doubt. Such doubt
stimulates a search for new and dif-
ferent methods of confirmation for his
reassurance. Frequent self-appraisals
should embrace every step—from col-
lecting samples to reporting results.
The analyst's first critical scrutiny
should be directed at the entire sample
collection process in order to guarantee
a representative sample for the purpose
of the analysis and to avoid any pos-
sible losses or contamination during the
act of collection. Attention should also
be given to the type of container and to
the manner of transport and storage, as
discussed elsewhere in this volume.
A periodic reassessment should be
made of the available analytical meth-
ods, with an eye to applicability for
the purpose and the situation. In ad-
dition, each method selected must be
evaluated by the analyst himself for
sensitivity, precision and accuracy,
because only in this way can he deter-
mine whether his technic is satisfactory
and whether he has interpreted the di-
rections properly. Self-evaluation on
these points can give the analjst confi-
dence in the value and significance of
his reported results.
The benefits of less rigid intralabora-
tory as well as interlaboratory eval-
uations deserve serious consideration.
The analyst can regularly check stan-
dard or unknown concentrations with
and without interfering elements, and
compare results on the same sample
with other workers in the laboratory.
Such programs can uncover weaknesses
in the analytical chain and enable im-
provements to be instituted without de-
lay. The results can disclose whether
the trouble stems from faulty sample
treatment, improper elimination of in-
terference, poor calibration practices,
sloppy experimental technic, impure or
incorrectly standardized reagents, de-
fective instrumentation, or even inad-
vertent mistakes in arithmetic.
Other checks of a water analysis are
described in Section 100C and involve
anion-cation balance, specific conduc-
tance, ion exchange, and the recovery
of added substance in the sample (see
also Section OOOA.10 preceding).
All these approaches are designed to
appraise and upgrade the level of lab-
oratory performance and thus inspire
greater faith in the final reported re-
sults.
rr*ii.-
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36-*?-
200 D. Methods Evaluation by the Co.T.miiree
The Committee on Standard Meth-
ods of the Water Pollution Control
Federation has attempted to establish
the precision and accuracy of the
methods in Part 200. For many meth-
ods, results were obtained from tea
replicate determinations on 10 different
days or, when necessary, from five
replicate samples on 20 days.
Most methods studied were found to
be statistically reliable, and the standard
370
each test, the number of analysts and
determinations is given in shorthand
form; for example, "« = 5; 56x10,"
which means that 5 different analysts
ran 56 separate sets of 10 determina-
tions each, making a total of 560 de-
terminations. Usually the precision is
expressed as the standard deviation in
original units of measurement—i.e.,
milligrams or miilUiters. In a few in-
stances, the precision is expressed as
the coefficient of variation C, (the ratio
of the standard deviation to the aver-
age), expressed as a percentage:
deviations given may be used with
some confidence in sutistical predic-
tion. If a method has been found
statistically unreliable, this is indicated
in the statements on precision under
the method. The standard deviations
of unreliable methods cannot safely be
used for statistical prediction, but may
be of some value for indicating roughly
the variation that may be expected.
In expressing the e\aluation data on
POLLUTED WATERS (200)
C.=
ICO a
The standard deviation given with
each method is based on careful labora-
tory examination. No attempt has
been made to obtain the standard devia-
tion under research conditions, or with
the use of specially calibrated apparatus
or glassware. The values given are
to be regarded as provisional in nature
and subject to change on further study.
In general, the standard deviations
given may be regarded as being too
high rather than too low.
as
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8-24
-------
8.3 Specific Analytical Methods for the Analysis of Relatively Concentrated
Leachate Samples
8.3.1 Introduction
Specific analytical methods for the analysis of relatively concentrated
leachate samples were investigated in the report "Compilation of Methodology
for Measuring Pollution Parameters of Landfill Leachate": by E.S.K. Chian
and F.B. DeWalle, University of Illinois, EPA Program Element No. 1DB064. It
is stated in the abstract, P. IV of the subject report:
"Since different analytical methods can be used to determine a specific
parameter, a preliminary laboratory evaluation was made of those methods least
subject to interferences. All analyses were conducted with a relatively con-
centrated leachate sample obtained from a lysimeter filled with milled solid
waste. The results indicate that strong interferences are sometimes encountered
when using colorimetric tests due principally to the color and suspended
solids present in leachate. In such instances, alternative methods were evalu-
ated or recommendations were made to reduce the interfering effects. Automated
chemical analysis using colorimetric methods can sometimes experience significant
interferences.
Further research is necessary to evaluate additional methods using leachate
samples of different strengths and collected from landfills of different ages.
The precision and sensitivity of each method will also have to be determined.
The interfering parameter should be quantified to allow predictions of its
magnitude with leachate samples of different strengths."
Also, in the above-cited report, Introduction, P.3, it is stated:
"It is the purpose of the present study to review the analytical methods to
determine contaminants as reported in the literature. The methods compiled and
8-25
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evaluated in this study were generally reported in the literature; additional
information was obtained by contacting the principal investigators. Interferences
in the chemical analysis due to the complex nature of the leachate as enumerated
in the reported studies are listed in this report.
The compilation showed that different methods subject to different interferences
are used to determine a certain parameter. For each parameter, only that method
was evaluated in this laboratory which was found to have the smallest interference.
The laboratory evaluation tested the method for its susceptibility to certain
interferences commonly found in leachate. In addition, the accuracy of the
method was tested. All laboratory analyses were performed using a high strength
leachate sample obtained from a recently installed lysimeter filled with milled
refuse. Recommendations made in this report, therefore, only apply to leachate
of similar strength. No evaluation was made of precision and sensitivity of
each method since this was beyond the scope of the work. Realizing the above
restrictions, recommendations were made in the present study for the selection
of those methods least subject to interference. Further recommendations were
made concerning modifications of the selected methods."
8.3.2 Measurement of Interference Effects
Two general procedures were used by Chian and DeWalle to deal with interference
effects in their evaluation of specific analytical methods. These procedures
were the Standard Addition Method and the Dilution Method. These methods are
discussed in this report on pp. 12-15, which are reproduced herewith.
In general, it would be expected that interferences encountered in concentrated
leachates would be relatively severe and constitute "worst case" effects when
compared with more dilute leachates. Leachates obtained in the field (landfills)
for analysis may vary greatly in total concentration, i.e. from total concentration
8-26
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If (AS REPRODUCED FROM CHIAN AND DeWALLE REPORT)
j SECTION 5
METHODOLOGY OF METHOD EVALUATION
i*
•j Since most of the leachate studies have been conducted by researchers in
' the sanitary or environmental engineering fields, the methods that are used
closely reflect those of Standard Methods (APHA, 1971). Studies between
I960 and 1965 used the llth edition, between 1965 and 1971 the 12th edition
and after 1971 the 13th edition. Laboratories not employing complicated
instruments, sometimes use methods listed by Hach Chemical Company, Handbook
of Water Analysis (Hach Chemical Company, 1973). Methods used by geologists
are generally those reported in Techniques of Water Resources Investigation
of the U. S. Geological Survey (U. S. Geological Survey, 1970). Recent
studies use the EPA procedures in Methods for Chemical Analysis of Water
and Hastes (EPA, 1974) which also contain optional procedures for automated
analysis. Most studies employing automated chemical analysis, however, use
methods recommended by Techm'con Industrial Systems. Industrial Methods
(Technicon, 1973). -
The different parameters that have been determined in the studies
reported in the literature are listed below. Each section contains a survey
of the different methods used to analyze a certain parameter, and the obtained
experiences. The method least interferred with by the matrix of the leachate
sample was selected and then evaluated in greater detail in the present
study. The method was evaluated with the standard addition method and by using
progressively increasing dilutions.
5.1 STANDARD ADDITION METHOD
The standard addition method is widely used in chemical analysis when
interferences present in the sample cannot be avoided. An advantage of
this method is that it avoids the necessity of preparing synthetic standards
of a composition similar to that of the sample (Geological Survey,
1970). In this method equal volumes of sample are added to a water blank
and standards containing increasing but known anounts of the test element.
The volume of the blank and the standards must have the same volume to result
in a similar dilution of the sample. The diluted samples containing increasing
amounts of the test element are then analyzed according to the standard
procedures. The obtained values are then plotted on the vertical axis of a
graph while the concentration of the known standards are plotted on the
horizontal axis (Figure 3). When the resulting line is extrapolated to
zero measured concentration, the point of interception of the abscissa is
the concentration of the unknown element. The abscissa on the left of the
ordinate is scaled the same as on the right side, but in the opposite
= direction of the ordinate. Since the scale of the ordinate and abscissa
are identical, a line drawn under 45° from the extrapolated point on the
"abscissa to the ordinate represents a 100 percent recovery of the added
element. Thus 100 percent of the known amount added to the diluted sample
is recovered. If the actual line connecting the points has a slope lower
* than 45° the recovery of the added element is less than 100 percent while a
slope higher than 45° represents a higher than ICO percent recovery. The
] 8-27
-------
1.0
0.8
O
!o
o
s
o
o
•o
0>
t-
0>
§
o
a:
0.6
0.4
0.2
Extrapolated
Concentration, mg/J?
Measured With
Standard Addition
(O
i:50 Dilution
(72.5 % Recovery)
I MOO Dilution
(83 7o Recovery)
100 % Recovery
I I
0.2
0
0.2
0.4
06
Added Concentration Total-P, mg/J
Figure 3.
The Total-P Determination with the Ascorbic Acid
Method in the 1:50 and 1:100 Diluted Leachate
Sample Using the Standard Addition Method
8-28
-------
.»
:|
8-29
-------
bUtttW4ftS9BUiVCH.CKBiXBIii^ 4lfc44&l
W
o
I I I I
l?750 1:400 1:250 IM25 1:100
1:500 1:300 1:200
Dilution Factor
1:75
1:50 1:40 1:30 1:20
Figure 4. The Total-P Determination with the Ascorbic Add Method 1n a Leachate
Sample Using the Progressive Dilution Method
i i« •'
-------
of minimum detectability to a highly concentrated product. The ratios of
the individual contaminants present in the leachate are also variable and
must be considered when evaluating interference effects in a given analytical
method.
The analyst, therefore, must always evaluate a specific analytical method
relative to a specific leachate sample. Several guidelines for handling inter-
ferences are of great value. The judgment of the analyst is of prime importance
in applying the guidelines to Uhe specific problems at hand. Experience with
a given leachate is obviously of practical value. The degree of accuracy,
sensitivity and precision required in a specific analytical problem will con-
stitute foremost considerations in the final selection of the method and possible
modifications.
8.4 Analytical Methods
In discussing individual analytical methods in their report, Chian and DeWalle
address the following aspects in each case:
Principle, Interferences, Previous Studies, Evaluation of The Method, Recommenda-
tions and Procedures.
The methods discussed in the report are as follows:
1. Physical Parameters: pH, Oxidation Reduction Potential (ORP) and Specific
Conductance, Residue.
2. Organic Chemical Parameters: C.O.U., T.O.C., Volatile Acids, Tannin and
Lignin, Organic Nitrogen.
3. Inorganic Chemical Parameters: Chloride, Sulfate, Phosphate, Alkalinity
and Acidity, Nitrate, Nitrite, Ammonia, Sodium and Potassium, Calcium
and Magnesium.
8-31
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4. Biological Parameters: B.O.D., Coliform Bacteria (Total and Focal).
5. Miscellaneous Determinations
Tlic report also contains a useful appendix of parameters and methods used by
various investigators. (Appendix A, P. 125 - Survey of physical, chemical
and biological methods used by various investigators).
3.5 Brief Description of Specific Analytical Methods for Leachate Analysis
Following is a brief description of the analytical methods as recommended by
Chian and DeWalle for the analysis of concentrated leachate:
1. Physical Parameters:
A. pH Determination:
Electronetric determination using a glass indicating
electrode and a calomel reference electrode or a combination
electrode. The procedure is according to Standard Methods,
13th Edition, 1971, p.279.
B. Oxidation Reduction Potential (ORP):
The measurement is made with a pH meter, using a platinum
indicating electrode and a calomel reference electrode. The
pH determination is made concurrently.
C. Specific Conductance Determination:
The determination is performed with a commercially available
meter and an electrode with a cell constant of 1.0. Both tempera-
ture and pH are determined concurrently, as they affect the results.
Reference is made to Standard Methods. 13th Edition, 1971, pp.326-327.
I). Residue Determination:
Total solids is determined after drying to constant weight
at 103-105°C. and the volatile solids is determined from the weight
8-32
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loss at 550°C. for one hour. The suspended solids(filterable
residue) is determined using a glass fiber filter and drying
to constant weight at 103-105°C. The following reference is
given: Standard Methods. 13th Edition, 1971, pp. 289,292,293
2. Organic Chemical Parameters:
A. Chemical Oxygen Demand (C.O.D.):
The C.O.D. determination is performed according to Standard
Methods. 13th Edition, 1971, pp. 496-499. If the C.O.D. is less
than 100 mg/liter, more accurate results may be obtained by using
the low level C.O.D. procedure given on p. 498 of the same refer-
ence.
B. Total Organic Carbon (T.O.C.):
The T.O.C. analysis is run according to Standard Methods.
13th Edition, 1971, pp. 257-259.
C. Volatile Acids (Total Organic Acids):
Volatile acids are determined by the column-partition
chromotographic method as listed in Standard Methods. 13th
Edition, 1971, pp. 577-580. Standard amounts of acid are added
to determine the recovery of the method.
D. Tannin and Lignin
The tannin and lignin procedure is according to Standard
Methods. 13th Edition, pp. 346-347.
E. Organic Nitrogen:
Organic nitrogen is determined according to Standard Methods.
13th Edition, pp. 244-248. A 300 ml. sample, 50 ml. digestion
reagent and 30 min. digestion period are used.
8-33
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3. Inorganic Chemical Parameters:
A. Chloride:
In biologically stabilized leachate samples in which
color does not cause any interference, the chloride deter-
mination is conducted with the mercuric nitrate method
(Standard Methods.13th Edition, pp. 97-99). In strongly
polluted leachate, chloride is determined by the poten-
tiometric titration method (Standard Methods. 13th Edition,
pp. 377-380).
B. Sulfate:
Sulfate is determined by the gravimetric method with
drying of residue, according to Standard Methods. 13th Edition,
1971, pp. 332-333.
C. Phosphate:
The aminonaphthol sulfonic acid or ascorbic acid method
is used to measure total phosphorus concentration in leachate
using the persulfate digestion. The amount of recommended per-
sulfate digestion reagent is 400 mg./lOO nl. sample, while the
digestion tine recommended by Standard Methods is sufficient to
hydrolyze the phosphorus. The ortho-phosphate test as determined
by the ascorbic acid method does not experience significant
interference and should be run on the anaerobically stored
leachate after as little dilution as possible. In order to obtain
reliable results, a standard addition or progressive dilution
curve should be established for the total phosphorus determination.
Such steps are not necessary for the orthophosphate determination
teferences for the total phosphate and ascorbic acid methods are
Standard Methods. 13th Edition, 1971, pp. 524-526 and 532-534.
8-34
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The aminonaphthol sulfonic acid method reference is Physical.
Chemical and Microbiological Methods of Solid Waste Testing;
Four Additional Procedures; N. S. Ulmer, U.S.EPA, NERC,
Cincinnati, 1974.
D. Alkalinity and Acidity:
The alkalinity and acidity determinations are made poten-
tiometrically on undiluted samples. The endpoints used are those
determined from the titration curve. Standard 0.02N NaOH is
used for the acidity determination and standard 0.02N H2S04
or HC1 is used for the alkalinity determination. Reference is
Standard Methods. 13th Edition, 1971, pp. 52 and 55.
E. Nitrate:
Nitrate is determined with the specific ion electrode instead
of the brucine-sulfanilic acid colorimetric method. It is preferable
to measure the nitrate with the electrode in the undiluted sample.
Standard amounts of nitrate should be added to the sample to de-
termine the recovery of the method. When the brucine-sulfanilic
acid method is used, the suspended solids and color may be removed
with a massive lime dosage of 5,000 to 10,000 mg./l. Ca(OH)2.
Aluminum hydroxide is not as effective as a coagulant.
F. Nitrite:
Nitrite is determined by the naphthylamine colorimetric pro-
cedure as outlined in Standard Methods. 13th Edition, 1971,pp.240-243.
The naphthylamine reagent is replaced by n- (1-naphthyl) ethylene-
diamine dihydrochloride.. Standard amounts of nitrite nitrogen are
added to the filtered sample.
G. Ammonia
Two methods are recommended for determination of ammonia.
One uses the selective ion electrode with sufficient sample dilution
8-35
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to reduce matrix interference of the leachate. (Reference:
U.S. EPA Methods for Chemical Analysis of Water and Wastes.
1974, pp. 165-167). The other method uses distillation followed
by titration of the ammonia in the distillate with standard 0.02N
H2SO^, with mixed methyl red-methylene blue as the indicator.
For this method, a maximum concentration of 75 mg/1. ammonia
in the diluted sample is recommended, unless additional buffer is
used. A pH of 7.4 is sufficiently high to distill off the ammonia.
A pH 9.4 is too high, causing partial destruction of the organic
nitrogen. (Reference: Standard Methods. 13th Edition, 1971,
pp. 224-226 and 246-247).
H. Sodium and Potassium:
Sodium and potassium are determined by flame photometry
(Reference: Standard Methods. 13th Edition, 1971, pp. 316-320,
Sodium and pp. 283-284, Potassium). Sodium and potassium may
also be determined by atomic absorption spectroscopy, in which
case it is recommended that cesium be added at a concentration of
1,000 mg./l. to suppress ionization of the analyte ion in the flame.
(Reference: Methods for Chemical Analysis of Water and Wastes.
U.S.EPA, 1974: Sodium, pp. 147-148 and Potassium, pp. 143-144).
I. Calcium and Magnesium:
Calcium and magnesium are determined by atomic absorption
spectroscopy, using 10,000 mg./l. lanthanum to reduce interference.
(References: Standard Methods. 13th Edition 1971, pp. 212-213 and
Methods or Chemical Analysis of Water and Wastes. U.S. EPA, 1974,
pp. 103-104, Calcium and pp. 114-115, Magnesium).
8-36
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J. Hardness:
Hardness is calculated from the concentrations of the
individual polyvalent metals as determined by atomic absorption
spectroscopy and should include Ca, Mg, Fe, Al, Zn, Cu and other
polyvalent cations, expressed as CaC03 equivalents.
K. Heavy Metals:
The heavy metals are determined with atomic absorption
techniques. Standard additions are used for leachates of high
strength to determine the magnitude of the interference. Stan-
dard additions should be used for the elements lead, copper,
nickel and chromium but may be omitted for zinc and cadmium.
For total metal analysis, the sample should be collected in a poly-
ethylene bottle and acidified to pH2 with 1:1 redistilled nitric
acid. When the dissolved metals, those filterable through a
0.45/*- filter, are determined, the suspended metals should be
determined concurrently. f
The determination of arsenic and selenium by atomic absorption
using the gaseous hydride method may not be satisfactory, since
reduction to the trivalent form with SnCl2 may not be complete.
The conversion to gaseous arsine after addition of zinc metal may
also not be complete. Colorimetric methods are therefore recommended.
The analysis of mercury by atomic absorption with the cold vapor
technique also depends on the reduction of the sample with SnSO^
or SnCl2» which may not be complete when other oxidants in high
concentrations are present. (References: Standard Methods, 13th
Edition, 1971, p. 213; Methods for Chemical Analysis of Water and
Wastes. U.S.EPA, 1974, pp. 213 and 295-299, Selinium; Methods for
8-37
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Chemical Analysis of Water and Wastes, U.S.EPA, 1974, Calcium
pp. 103-104, Magnesium pp. 114-115, Iron pp. 110-111, Aluminum
pp. 92-93, Zinc pp. 155-156, Copper pp. 108-109, Arsenic pp.9-10
and 95-96, Selenium p. 145, Mercury pp. 118-122).
4. Biological Parameters:
A. Biochemical Oxygen Demand (B.O.D.):
The B.O.D. determination is run according to Standard Methods,
using dilution water which is seeded with settled domestic sewage.
B.O.D. values obtained should be judged carefully and be determined
parallel with comparable chemical tests such as free volatile fatty
acids, C.O.D. or T.O.C. (Reference: Standard Methods. 13th Edition,
1971, pp.489-495).
B. Colifonn Bacteria (Total and Fecal):
The most probable number (MPN) technique should be selected for
leachate monitoring purposes, as opposed to the membrane filter (MF)
technique, since it is able to detect bacteria at lower concentrations
and is less subject to suspended solids interference. Inactivation
studies, however, in which a certain amount of bacteria is added to
a sample to study its subsequent reduction with time, should be
conducted if the MF technique is used. Presumptive and confirmed
tests are run for total coliforms and the completed coliform test
is run in those instances where leachate causes pollution of drinking
water supplies. (Reference: Standard Methods. 13th Edition, 1971,
pp. 664-668).
The fecal coliform MPN procedure is used as a confirmatory
test procedure in conjunction with prior enrichment in a presumptive
test medium for optimum recovery of fecal coliforms. (Reference:
Standard Methods, 13th Edition, 1971, pp.669-672)
8-38
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5. Miscellaneous Determinations:
Some of the miscellaneous leachate parameters which have
been given attention in various studies are: Methylene blue
active substances, cyanide, fluoride, sulfide, si lien, hcxanc
solubles, ether solubles, color, visual appearance- and odor.
8.5.1 Additional valuable information on specific analytical methods is
available in "Procedures for the Analysis of Landfill Leachate", Proceedings
of an Internation Seminar, Environmental Conservation Directorate, Ottawa,
Ontario, Report EPS-4EC-75-2, October 1975.
8.6 Field Testing Versus Testing in the Laboratory
The majority of tests performed on leachate samples are carried out in the
analytical laboratory on samples which have been preserved by refrigeration
or chemical means. A limited number of tests, however, can be performed at
the sampling site on a freshly drawn sample. There are a number of advantages
in field testing, among which are that sample degradation is practically
eliminated, along with the need for sample preservation, transportation and
handling. An added advantage is the ability to re-sanple and re-analyze
immediately, on site, if it is suspected that a particular sample is not
representative or valid. There are also disadvantages encountered in field
testing and these usually relate to the reliability of the particular method
and equipment used for the test.
Some tests can be run in the field with the same methods and equipment
which would be used in the laboratory and yield the same reliability. Among
such tests are those involving the measurement of pH, oxidation reduction
potential, specific conductance, turbidity, dissolved oxygen and specific
ions by means of specific ion electrodes. The equipment used in these tests
is available in portable models which are of equal applicability in the field
and laboratory.
Other tests are sometimes performed in the field using methods and equipment
8-39
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specifically designed for field use. A number of commercially available
kits are available for such purposes. These methods are not usually used
in the analytical laboratory and are generally recognized as being applicable
only to field testing.
While offering distinct advantages, there are also disadvantages inherent
in the use of field kits. The following evaluation of field kit usage is
given in Handbook for Monitoring Industrial Wastewater. U.S. EPA, Technology
Transfer, August 1973, p. 5-141
"Estimating the Amounts of Pollutants Present by Use of "Kits""
Companies, such as the Hach Chemical Company, Delta Scientific, Inc.,
and Koslow Scientific Company have manufactured "Kits" for the analysis of
various constituents of wastewater. The kits consist of a small portable
container in which all the necessary equipment and instructions are conveniently
packaged and arranged to perform a variety of tests. No previous laboratory
training is required and, within minutes, an indication of the chemical con-
stituents in wastewater can be determined.
Koslow Scientific and the Hach Company provide kits for determining
the presence of heavy metals, such as Cd, Hg and Pb, and includes reagents
for masking interferences.
The major disadvantage in using kits is the inability of the pre-packaged
devices and reagents to effectively cope with interferences. Reference 2
(Standard Methods for the Examination of Water and Wastewater. 13th Edition,
American Public Health Association, 1971) outlines procedures for the
removal of interferences by pretreatment techniques and the reagents necessary
for masking these interferences that are usually not available in the kits.
The accuracy of the tests performed with kits is usually less than that obtain-
able with precise laboratory techniques. Kits give good results in relatively
&-40
-------
clean water but pose problems when used to anlayze wastewaters. They
are nevertheless useful in preliminary surveys performed to determine
overall characteristics of a wastewater."
This evaluation of the use of field kits for the analysis of indus-
trial wastewater is equally applicable in the case of leachate analysis.
Mobile Laboratories
Although not in widespread usage, mobile analytical laboratories have
the potential of providing a combination of laboratory capability and field-
testing convenience. The instrumentation and general capability of a mobile
laboratory can vary over a wide range, depending upon its application, manpower,
and the capital investment involved. By using normal laboratory equipment and
methods, the mobile laboratory can obtain results equivalent to those of a
conventional analytical laboratory, while incorporating all of the advantages
of field kits. Limitations imposed by sample degradability and work load will
be encountered by the mobile laboratory in much the same way as experienced
by the conventional laboratory under certain conditions. If a sample or
samples presented to a mobile laboratory must be analyzed for a large number
of parameters (i.e. 20 or 30), then sample degradation versus work load will
have to be addressed. The sample will have to be preserved and the analyses
prioritized relative to order of degradability. In this respect, the mobile
laboratory shares the disadvantages of the conventional laboratory, along with
its advantages.
8.7 Automated Methods
Automated wet chemistry methods offer riany advantages, among which are
economy, increased precision and accuracy when applied to repetitive analytical
work loads of significant volumes. Federal, state and local regulatory agencies,
industry, educational institutions and independent testing laboratories, among
8-41
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others, use automated methods to handle large, demanding repetitive analytical
work loads.
Automated wet chemistry is addressed in the "Handbook for Monitoring
Industrial Wastewater", U.S. EPA, August 1973, pps. 5-14, as follows:
"Automated wet chemistry is frequently used in analysis of
wastewaters and for automated monitoring of waste effluents. When
used, the system consists of a sampler to select air, reagents,
diluents and filtered samples. From the sampler, the fluids pass
through a proportioning pump and manifold where the fluids are
aspirated, proportioned and mixed. The samples are then ready
for separation by passing through any one of the following units:
a dialyzer (continuously separates interfering materials in the
reaction mixture) a digester (used for digestion, distillation or
solvent evaporation), a continuous filter (for on-stream separation
of particulate matter by a moving belt of filter paper) or a distilla-
tion head (separates high vapor pressure components).
After separation, the samples can be conditioned in a constant
temperature heating bath. After conditioning, the samples pass
through a detection system which may be a colorimeter, a flame
photometer, a fluorometer, a UV spectrophotometer, an IR spectro-
an atomic absorption spectrophotometer,
photometer,/or a dual differential colorimeter. The signals from
the detection system are sent to a recorder or a computer system."
In the May 1975 issue of "Environmental Newsletter", a publication of
Technicon Industrial Systems, a list of water quality major automated methods
is presented. The list is reproduced below. It should be noted that ten (10)
of the methods are Federal Register approved and eleven (11) of the methods
are presented in the U.S. EPA manual "Methods for Chemical Analysis of Water
and Wastes", 1974.
8-42
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P,3,,«» 1 CLASSIFICATION OF MAJOR METHODS FOR AUTOANALYZER 1 AND II SYSTEMS
Parameter
Acidity (Thymol Blue)
Alkalinity (Methyl Orange)
Aluminum
Ammonia (Dialysis)
Boron
..Chloride "• "•.''-;• ,~V- '. j'\ - rv"«'Ij!.''i^
. Chromium (Hexavalent) .- '-",.-r_/. :;./•;
- COD «•':•":•"• '-"•'•"-.. •"• 1.-"-", " •-
* Color ""' ••••£.. T .•• "• '"••' 5y-iVii"if-*"?-"s5
" Copper ''. '' '--•'." '"•' ".•"./.• -;;,'
Cyanide
Fluoride
Hardness (Total)
Iron
Ma.-cury
••'ate & Nitrite (Dialysis)' -.?.Xr-.--'^V
.gen (Ammonia) -•' .• ../"" "O'V^-"
• Nitrogen (Kjeldahl. Total) ":.•'•„• !;"";'
. Nitrogen (Nitrite) '• ' - *""';" --""';t't
Nitrogen (Nitrate & Nitrite) ' '..'- -:..-'"
Nitrogen (Organic plus Ammonia)
NTA
Phenol
Phosphorus (Total)
Phosphorus (Total)
Pnosphorus {O-phosphate) _ ; -. •• . -.
Silicates - • ' • - '• . ' -
Sucrose - ' ' • . ...
Sutfate " ' ' ; ' :•-
Su'.fite .' ' ._ .'_'- _*"
Technicon
or
)ther Method
_^_ -
164-71W
111-7UV
(4)
270-73W
202-72W
.99-70W -.-:
162-71VV .-
137-7 1W •-'
181-72W ."
315-74W
129-7UV
165-7 1W
109-71W
_
271-73W. .
J46-70W '. .
102-7ffW .
100-70W /_
325-74W(5)
127-7HV
94-70W(6)
297-73W
188-72W
94-70W
105-71W
274-7 3W -
289-73W •
118-71W '
173-72VV .
Federal
Register
Approved
X
'••-.^.X's-.^
* -_* ***•",••" "-• '
. "* ' T "*.*""* ^
t .... — , . .^
X
-
:*ft'^
.'•'':.:'x;-:.;
X
- x
•"••"." '.-"•'-•'.
Individual
Variance
Approvals
3?&^'.i:.
fe^V '-""-'>
"-Vr -7;':?i"
"-;./":. " .~
X
::>"-: "•'-•'-•/-.
^ !,-»->• ••-"-
x
X
• 1 ." •
•"
* -•' tf --",; ""
.-, c.t-.-.---,:,-
1974 EPA
Methods Book
Reference (D
P. 5
P.31; 7- . ;
~J-£-T '. ":-'.-.--"-V-V
- - :•• •
P. 61
P. 70
P. 127
P. 168 '*'.'. j
P. 190(SeO2) '
P. 220
P. 243
P. 256
•,>>;.__,-.
'•'"".'.' :- -
PI279.
Practical
Method<2)
X
X '
X
-. V.- - " ^
::\'^ ^
_.-_'X-..
X
X
X
'~:":':&
•• '-i" -:-"/:..
X
-.vx'-:
:v:x...
- . : x; >
Usual
Method
Range '3)
0-500mg/l
0-500mg/l
0-1mg/l
0-1mg/l
0-0.2mg/l -;":"-']
0-100mg/l ":-:1
0-250 Units . '!
0-2mg/l - ,,
0-500 pg/l
0-2mg/l
0-250mg/l
0-1mg/l (ppm)
0-20 pg/l
0-1mg/l -""'t-i
0-10mg/l "---i.- •]
0-10mg/l • '~^'A
• ' •• ."•* - ' --" '"(
0-1mg7l (N) :'\
0-2mg/l (N) "J
0-0.40mg/l
or 0-10mg/l
0-10mg/l
0-500 pg/l
0-10mg/l
0-10mg/l
0-lmg/l
0-10mg/l •-•{
0-10mg/l / i
0-IOOmg/l '"}
0-300mg/l . j
. 0-3mg/l ." 1
1) S3t« EPA f/ethoc!s may differ in detail from the Technicon Listed Method. In such wses the method to be selected for use is
determined by review of sample matrices and ranges required
2) Method in practical use but gzn»ral regulatory approval not yet obtained
3) I.:e:hod ranees can be adjusted to suit particular rweds. Method resolution is typically 1% of f-jil scale.
A] fConvegien Institute for Water Research. Oslo. Norway, A. Henderson . I
•=« Manual d-s«tion folloivsd by autoanalysis for ammoniacal nitrogen. _ I
ii:s eo»»on»TiC"
8-43
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Automated methods are discussed in "Standard Methods for the Examination
of Water and Wastewater", 13th Ed., 1971, pps. 14-15, as follows:
"Automated analytical instrumentation: Automated analytica]
instruments are now available and in use to run individual samples
at rates of 10 to 60 samples per hour. The same instruments can
be modified to perform analyses for two to twelve constituents
simultaneously from one sample. The instruments are composed of
a group of interchangeable modules joined together in series by a
tubing system. Each module performs the individual operations
of filtering, heating, digesting, time delay, color sensing, etc.
that the procedure requires.
The read-out system employs sensing elements with indicators,
alarms and/or recorders. For monitoring applications, automatic
standardization-compensation, electrical and chemical, is done by
a self-adjusting recorder when known chemical standards are sent
periodically through the same analysis train. Such instrument
systems are presently available.
Appropriate methodology is supplied by the manufacturer
for many of the common constituents of water and wastewater.
Some methods are based on procedures described in this manual, while
others originate from the manufacturer's adaptation of published
research. Since a number of methods of varying reliability may
be available for a single constituent of water and wastewater, a
critical appraisal of the method adopted is obviously mandatory.
Automated methodology is susceptible to the same interferences
as the original method from which it derives. For this reason, new
methods developed for automated analysis must be subjected to the
exacting tests for accuracy and freedom from adverse response already
met by the accepted standard methods.
8-44
-------
Off color and turbidity produced during the course of
an analysis will be visible to an analyst manually performing a
given determination and the result will be properly discarded.
Such abnormal effects caused by unsuspected interferences might
escape notice in an automated analysis. Calibration of the
instrument system at least once each day with standards containing
interferences of known concentration could help to expose such
difficulties. Routine practice is to check instrument action
and guard against questionable results by the insertion of
standards and blanks at regular intervals - perhaps after every
10 samples in the train. Another important precaution is proper
sample identification by arrangement into convenient groups.
In brief, a fair degree of operator skill and knowledge,
together with adequately detailed instructions, is required for
successful automated analysis."
In the report "Compilation of Methodology For Measuring Pollution Parameters
of Landfill Leachate" by E.S.K. Chian and F.B. DeWalle, the following comments
are made concerning automated methods:
"All automated methods as recommended by EPA (1974) for water
and wastewater and Technicon (1973) for industrial waste should
be evaluated for possible interferences since most tests are
based on colorimetric analyses which are generally subject to
strong interference by the color and suspended solids present in
leachate. Such evaluation is necessary since increasing amounts
of leachate samples will be analyzed by automated methods at a future
date."
Laboratory Quality Control
The subject of laboratory quality control is treated in detail in "Hand-
book For Analytical Quality Control in Water and Wastewater Laboratories",
8-45'
-------
U.S. EPA Technology Transfer, June 1972. The various topics covered include:
Importance of Quality Control, Laboratory Services, Instrumental Quality
Control, Glassware, Reagents, Solvents and Gases, Control of Analytical
Performance, Data Handling and Reporting, Special Requirements for Trace
Organic Analysis and Skills and Training. A number of valuable references
are provided in each section. Chapter 1, Importance of Quality Control is
reprinted below:
(pp. 8-47, 8-48, 8-49)
The technical and legal aspects of an adequate quality control program
are of prime importance in the analysis of sanitary landfill Jeachate samples.
The investment of time and effort needed for a quality control program are
well compensated in the resultant reliability of and confidence in the data
obtained.
8-46
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Chapter 1
IMPORTANCE OF QUALITY CONTROL
1.1 General
The role of the analytical laboratory is to provide qualitative and quantitative data to be
used in decision making. To be valuable, the data must accurately describe the character-
istics or the concentration of constituents in the sample submitted to the laboratory. In
many cases, an approximate answer or incorrect result is worse than no answer at all,
because it will lead to faulty interpretations.
Decisions made using water and wastewater data are far-reaching. Water quality standards
are set to establish satisfactory conditions for a given water use. The laboratory data define
whether that condition is being met, and whether the water can be used for its intended
purpose. If the laboratory results indicate a violation of the standard, action is required on
the part of pollution control authorities. With the present emphasis on legal action and
social pressures to abate pollution, the analyst should be aware of his^responsibility to
provide laboratory results that are a reliable description of the sample. Furthermore, the
analyst must be aware that his professional competence, the procedures he has used, and the
reported values may be used and challenged in court. To satisfactorily meet this challenge,
the laboratory data must be backed up by an adequate program to document the proper
control and application of all of the factors which affect the final result.
In wastewater analyses, the laboratory data define the treatment plant influent, the status
of the steps in the treatment process, and the final load imposed upon the water resources.
Decisions on process changes, plant modification, or even the construction of a new facility
may be based upon the results of laboratory analyses. The financial implications alone are
significant reasons for extreme care in analysis.
Research investigations in water pollution control rest upon a firm base of laboratory data.
The final result sought can usually be described in numerical terms. The progress of the
research and the alternative pathways available are generally evaluated on the basis of
laboratory data. The value of the research effort will depend upon the validity of the
laboratory results.
1.2 Quality Control Program
Because of the importance of laboratory analyses and the resulting actions wliich they
produce, a program to insure the reliability of the data is essential. It is recognized that all
analysts practice quality control to varying degrees, depending somewhat upon their train-
ing, professional pride, and awareness of the importance of the work they are doing. How-
ever, under the pressure of daily workload, analytical quality control may be easily
neglected. Therefore, an established, routine control program applied to every analytical test
is important in assuring the reliability of the final results.
The quality control program in the laboratory has two primary functions. First, the program
should monitor the reliability (truth) of the results reported. It should continually provide
an answer to "How good (true) are the results submitted?" This phase may be termed
"measurement of quality." The second function is the control of quality in order to meet
8-47
-------
the program requirements for reliability. For example, the processing of spiked samples is
the measurement of quality, while the use of analytical grade reagents is a control measure.
Just as each analytical method has a rigid protocol, so the quality control associated with
that test must also involve definite required steps to monitor and assure that the result is
correct. The steps in quality control will vary with the type of analysis. For example, in a
titration, standardization of the titrant on a frequent basis is an element of quality control.
In an instrumental method, the check-out of instrument response and the calibration of the
instrument in concentration units is also a quality control function. Ideally, all of the
variables which can affect the final answer should be considered, evaluated, and controlled.
This handbook considers the factors which go into creating an analytical result, and provides
recommendations for the control of these factors in order to insure that the best possible
answer is obtained. A program based upon these recommendations will give the analyst and
his supervisor confidence in the reliability and the representative nature of the sample
characteristics being reported.
Without exception, the final responsibility for the reliability of the analytical results sub-
mitted rests with the Laboratory Director.
1.3 Analytical Methods
In general, the widespread use of an analytical method indicates that it is a reliable means of
analysis, and this fact tends to support the validity of the test result reported. Conversely,
the use of a little-known technique forces the data user to place faith in the judgement of
the analyst. When the analyst uses a "private" method, or one not commonly accepted in
the field, he must stand alone in defining both his choice of the method and the result
obtained.
The need for standardization of methods within a single laboratory is readily apparent.
Uniform methods between cooperating laboratories are also important in order to remove
the methodology as a variable in comparison or joint use of data between laboratories.
Uniformity of methods is particularly important when laboratories are providing data to a
common data bank, such as STORET*, or when several laboratories are cooperating in joint
field surveys. A lack of standardization of methods raises doubts as to the validity of the
results reported. If the same constituent is measured by different analytical procedures
within a single laboratory, or in several laboratories, the question is raised as to which
procedure is superior, and why the superior method is not used throughout.
The physical and chemical methods used should be selected by the following criteria:
a. The method should measure the desired constituent with precision and accuracy
sufficient to meet the data needs in the presence of the interferences normally
encountered in polluted waters.
b. The procedure should utilize the equipment and skills normally available in the
average water pollution control laboratory.
*STORET is the acronym used to identify the computer-oriented U.S. Environmental
Protection Agency Water Quality Control Information System for STOrage and RETrieval
of data and information.
8-48
-------
c. The selected methods should be in use in many laboratories or have been sufficiently
tested to establish their validity.
d. The method should be sufficiently rapid to permit routine use for the examination
of large numbers of samples.
The use of EPA methods in all EPA laboratories provides a common base for combined data
between Agency programs. Uniformity throughout EPA lends considerable support to the
validity of the results reported by the Agency.
Regardless of the analytical method used in the laboratory.the specific methodology should
be carefully documented. In some water pollution reports it is customary to state that
Standard Methods (1) have been used throughout. Close examination indicates, however that
this is not strictly true. In many laboratories, the standard method has been modified
because of recent research or personal preferences of the laboratory staff. In other cases the
standard method has been replaced with a better one. Statements concerning the methods
used jn arriving at laboratory data should be clearly and honestly stated. The methods used
should be adequately referenced and the procedures applied exactly as directed.
Knowing the specific method which has been used, the reviewer can apply the associated
precision and accuracy of the method when interpreting the laboratory results If the
analytical methodology is in doubt, the data user may honestly inquire as to the reliability
of the result he is to interpret. ' '
The advantages of strict adherence to accepted methods should not stifle investigations
leading to improvements in analytical procedures. In spite of the value of accepted and
documented methods, occasions do arise when a procedure must be modified to eliminate
unusual interference, or to yield increased sensitivity. When modification is necessary the
revision should be carefully worked out to accomplish the desired result. It is advisable to
assemble data using both the regular and the modified procedure to show the superiority of
the latter. This useful information can be brought to the attention of the individuals and
groups responsible for methods standardization. For maximum benefit, the modified
procedure should be rewritten in the standard format so that the substituted procedure may
be used throughout the laboratory for routine examination of samples. Responsibility for
. the use of a non-standard procedure rests with the analyst and his supervisor, since such use
represents a departure from accepted practice.
•i
In field operations, the problem of transport of samples to the laboratory, or the need to
examine a large number of samples to arrive at gross values will sometimes require the use of
rapid field methods yielding approximate answers. Such methods should be used with
caution, and with a clear understanding that the results obtained do not compare in relia-
bility with those obtained using standard laboratory methods. The fact that "quick and
dirty methods have been used should be noted, and the results should not be reported along
with more reliable laboratory-derived analytical information. The data user is entitled to
know that approximate values have been obtained for screening purposes only, and that the
results do not represent the customary precision and accuracy obtained in the laboratory.
1.4 References
1. Standard Methods for the Examination of Water and Wastewater, 13th Edition Amer-
ican Public Health Association, New York (1971).
8-49
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The economics of quality control Is greatiy favored in the use of
automated analysis systems as compared to manual systems. In a recent
issue of the U.S. EPA Analytical Quality Control Newsletter (October 1975,
p. 5), it is stated that for a particular automated system, the additional
personnel work load required to provide an analytical quality assurance
overhead of 40%, is estimated to be about 1%. The 40 to 1 advantage is
most impressive. The newsletter article is reprinted below:
(p. 8-51)
8-50
-------
'• . •' .--'-.: :•• .-'.-.
5 . • ' •/:"--••,-•
r-.
ENVIRONMENTAL MONITORING AND SUPPORT LABORATORY-CINCINNATI, OHIO
- .'.'-.:• . AUTOMATED QUALITY ASSURANCE " ..." .';"•"
' "-":' J :' ."... . ' - .. '• . ' ". ' > ''"'. - .
In a number of progress reports on the Laboratory Autoaation System in this
Newsletter, it was pointed out that one of the goals of the project was a" ''1. '.-.
significant improvement in'analytical quality assurance techniques. Results '•-•;.-
obtained since installation 'last May have led us to the conclusion that a ' . V; -
quality assurance overhead.as high as 40% may be accoccodated in many analyses _' -
with a nominal increase in. personnel workload.* -••»-' • " •t./TVi*"^ .-"•• .-;'".f.-':
-..,:. -."•"• « .-- •- > - '<•• '>"».•-> - --;-:•••-•• -.-'•'3-Sisj '-*•*!-"->•"^'"' :-' -—.-'--"O
•?»•-?.<:^--^ ?--.--• ----.flp-r ^.**v:..-:-.-- - :•-. -• --.^^.v^y-? :;•-•:-. v>.
Quality assurance overhead is defined as the percentage of analytical measure- - -
._ _ _ j_ _»_t_ _ A- -« *. ~»_~__~_^_. * - - - - *- — * J«k*d» l*«>^ A«+fiA^» f»^»%my^ rf^tt ^*r%T% fr T*^% 1
- 1 •••'•
ments made that do not generate environmental data, but either provide control '..^;"
information to the operator, or assure Better overall quality of data. Check ,_.'„;_;..
standards, spikes; replicates, blanks, reagent blanks, and calibration standards"-.-.•.""-•
all contribute to this, overhead: . ^.-.V/Mv " V-u.-.f=.-. .j •-.-:'..''",'' 3.""i^*0."-5^?!'".•-- V'.^i-t"''''
AQC OVERHEAD = S™°£ Blanks * Replicates » Spikes * Standards x'ipO.f ":|^. ' ' 7.? >
; .-/•-•.JU'."'.-' ;i;-Sum of All Measurements 'Made ^ ^ ;._^_ ^'^5.-'^ 1 r.j::'J.;-
Check standards, "replicates,"and spikes should be measured at regular intervals "-
during the analysis of a series of environmental samples. The results of. these _ •-;.
sieasurements should be compared with historical data for that operator and that. .'. ,
nethod, and the information.used to determine whether the_analytical procedure
is in or out of control.', " *• \ '^': "^:--.y^'^ - - -^-."._;;^^^^' ^fr'r>'{*&&
Calibration standards, baseline blanks, and reagent blanks should be'measured "" j"
to assure better overall quality in the. data. Clearly the more calibration j "
•standards"T:he "better'the definition-of-the working calibration curve over a". :.~. -'
wider dynamic range.'• No assumptions of'linearity need be made. Similarly, .'!•_..•
frequent checks of baseline blanks are checks on baseline drift and no assump- "'..,
tions of'quiet baseline'need be made. Frequent checks of reagent blanks-assure ^-j^;;
that no reagent contamination, is a source of error. . All AO.A overhead measure- V"'..-,
sients contribute to cost in a manual' system'since each involves the attention /..
of personnel and time for calculations,. Often quality assurance overhead is " .._- '^
simply deleted to improve environmental sample throughput and reduce costs.
With the on-line, real time laboratory automation system, all of the above JlT-"".,'
quality assurance overhead has been fully integrated into the programs for "_•
operation of several instruments. In the specific case of the Technicon Auto
Analyzer, the additional personnel workload required to provide an AQA overhead
of 40% is estimated to.be about 1%. This consists largely of the time ^required '
to prepare spikes, blanks, and additional standards, and include them in the
analytical sequence. At the end of a series of measurements the instrument
operator devotes very little tine to data evaluation. Output reports contain
clear presentations of all quality assurance information and the frequent time
wasted because of uncertainties about the quality of the data is eliminated.
(Bill Budde, 513-684-2918) • : '."'.• ' - '. " 'V-; VO^'A;. ~'l*:'\
8-51
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Manpower and Skill Requirements
Manpower and skill requirements for analytical work are dependent
upon a number of factors, including nature of the sample, work load,
analytical parameter to be tested, method used, sensitivity, precision
and accuracy desired and equipment and facilities available. A considera-
tion of major importance, of course, is whether the analyses will be performed
by manual or automated methods.
In "Handbook For Analytical Quality Control In Water and Wastewater
Laboratories", U.S. EPA, June 1972, pp. 9-2, 9-3, 9-4, skills and skill-time
ratings for standard manual analytical operations are discussed in detail.
A reprint of this section is given below: pp. 8-53, 8-54, 8-55.
Manpower and skill requirements are reduced dramatically when automated
methods are used. The usual skill requirements are those of a technician
for preparation of samples, solutions, calibration and glassware handling.
Automated data processing affords additional manpower savings.
8-52
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9.2 Skills :
The cost of data production in the analytical laboratory is based largely upon two
factors-the pay scale of the analyst, and the number of data units produced per unit of
time. However, estimates of the number of measurements that can be made per unit of time
are difficult, because of the variety of factors involved. If the analyst is pushed to produce
data at a rate beyond his capabilities, unreliable results may be produced. On the other
hand, the analyst should be under some compulsion to produce a minimum number of
measurements per unit of time, lest the cost of data production become prohibitive. In the
following table, estimates are given for the number of determinations that an analyst
should be expected to perform on a routine basis. The degree of skill required for reliable
performance is also indicated. The arbitrary rating numbers for the degree of skill required
are footnoted in the tables, but are explained more fully below:
a. Rating 1-indicates an operation that can be performed by a semi-skilled
sub-professional with limited background; comparable to GS-3 through GS-5.
b. Rating 2-operation requires an experienced aide (sub-professional) with
background in general laboratory technique and some knowledge of chemistry, or a
professional with modest training and experience; comparable to GS-4 through
GS-7.
c. Rating 3-iridicates a complex procedure requiring a good background in analytical
techniques; comparable to GS-7 through GS-11.
d. Rating 4-a highly involved procedure requiring experience on complex
instruments; determination requires specialization by analyst who interprets results;
. comparable to GS-9 through GS-13 - - - -
The time limits presented in the table are based on use of EPA methods.
it
A tacit assumption has been made that multiple analytical units are available for
measurements requiring special equipment, as for cyanides, phenols, ammonia, nitrogen and
COD. For some of the simple instrumental or simple volumetric measurements, it is assumed
that other operations such as filtration, dilution or duplicate readings are required; in such
cases the number of measurements performed per day may appear to be fewer than one
would normally anticipate.
8-53
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Table 9-1
SKILL-TIME RATING OF STANDARD ANALYTICAL OPERATIONS
Measurement Skill Required (Rating No.) No./Day
pH
Conductivity
Turbidity (HACK 2100)
Color
DO (Probe)
Fluoride (Probe)
(Simple Instrumental)
1
1
1
1
1,2
1.2
(Simple Volumetric)
Alkalinity (Potentiometric)
Acidity (Potentiometric)
Chloride
Hardness
DO (Winkler)
Solids, Suspended
Solids, Dissolved
Solids, Total
Solids, Volatile
Nitrite N (Manual)
Nitrate N (Manual)
Sulfate (Turbidimetric)
Silica
Arsenic
,2
(Simple Gravimetric)
1,2
1,2
1,2
1,2
(Simple Colorimetric)
2
2
2
2
2,3
100-125
100-125
75-100
60-75
100-125
100-125
50-75
50-75
100-125
100-125
75-100
20-25
20-25
25-30
25-30
75-100
40-50
100-125
100-125
20-30
SKILL REQUIRED
1 - aide with minimum training, comparable to GS-3 through GS-5
2 - aide with special training or professional with minimum training,
comparable to GS-5 through GS-7.
3 - experienced analyst, professional, comparable to GS-9 through GS-12.
8-54
-------
Table 9-1 (continued)
SKILL-TIME RATING OF STANDARD ANALYTICAL OPERATIONS
Measurement
Skill Required (Rating No.)
(Complex. Volumetric or Colorimetric)
BOD
COD
TKN
Phosphorus, Total
Phenol (Dist'n only)
Oil & Grease (Soxhlet)
Fluoride (Dist'n)
Cyanide
2,3
2,3
2,3
2,3 .
2,3
2,3
2,3
2,3
(Special Instrumental)
2,3
No./Day
30-40*
25-30
25-30
50-60
20-30
15-20
25-30
10-15
150
60-80
3-5
2-4
Metals by AA
(No preliminary treatment) .
Metals by AA ' .2,3
(With preliminary treatment)
Pesticides by GC 3,4
(Without cleanup)
Pesticides by GC 3,4
(With cleanup)
SKILL REQUIRED
2 - aide with special training or professional with minimum training,
comparable to GS-5 through GS-7.
3 - experienced analyst, professional, comparable to GS-9 through GS-12.
4 - experienced analyst, professional, comparable to GS-11 through GS-13.
* - depends on type of sample. . . .".. ..
8-55
-------
Table 3. With automation. 3 people can handle three times the workload formerly handled by 12 people at
Parameter
Distilled fluoride '
.Distilled cyanide
Distilled phenol
Total phosphorus
Sulfate
Iron
Alkalinity
Cl
No!-N
NO^-N
-. " " "'
. Number ptr hour
-•••" .3-4 : --•
I' "-1-2 - '.'
•/ 3-4 ' -
- ;•; 6-8 .
'. ' '-is-is:' .- •
*;' • 10^12 . • '
10-12 ".
13-16
, ' 13-16'est.
10-13 '
5-7 ;
• -: 13-16
Manuel Me thoda.fr
- - Bench space
__ required
• - '• 10ft
" 15ft '
.- '.- 10 f I
" / " 5 r* -
••" ' 20 ft"
- ' * <- .
"5ft
5ft"
8ft
.8ft
8ft
':- 5 ft
Personnel
1 .
' '.' 1
'- . - ' 1 '
1 -
-,•'• I .
1 -.;" "
' '- . 1
. 1
1
1
1
•1
Automated Method
Number
per hour
4O
25
20
45 .
30
3O
3O
30
30
Bench space)
required
t
15 ft
t
-
t
15ft
l
•
t
15ft
1
Personnel?
•t
' 1 -"•
t -.
•
T
1
1
1
I
30
30
TOTAL
100-126
114ft
12
370
45 ft
" Source—Handbook for Anilylieil Quality Control In Water and Waslewiler Laboritorlti E!.P A » Includes "mP!|P'«£
cOne technician needed to prepare samples and glassware. t/AutoAnalyzer Unit can be used for o.her analyses. Source
Association. Floyd D. Kefford. , _
Water Works
932 Environmental Science & Technology
-------
A comparison of manual versus automated analytical methods for
throughput, space and personnel requirements is given in "Automated
Methods For Assessing Water Quality Come Of Age", by M.J.F. Du Cros and
J. Salpeter, Environmental Science and Technology, Vol. 9, Number 10,
Oct. 1975, p. 932. See Table No. 3 below (p.8-57).
Data are presented in tabular form for the analysis of 12 water
quality parameters. For the manual methods, 12 personnel and 114-feet of
bench space are required to perform 100 to 126 determinations per hour.
For the automated methods, 3 personnel and 45-feet of bench space are
required to perform 370 determinations per hour. In addition to an
appreciable savings of space, the automated throughput is approximately
12 times that achieved with manual methods.
Records, Data Handling and Reporting
A significant amount of analytical data are generated in a leachate
testing program. The data must be handled, interpreted, checked of validity,
recorded and reported. This is an important aspect of the testing program
and should be given appropriate attention. If the data are not properly
handled, the considerable effort and expense involved in sampling and analysis
can be lost or applied wrongly. It should be noted that legal, as well as
technical considerations can be associated with records, data handling and
reporting.
Reprinted below is Chapter 7, pp. 7-1 to 7-11, entitled "Data Handling
and Reporting", fron Handbook for Analytical Quality Control In Water and
Wastewater Laboratories, U.S.E.P.A., June 1972. Among the topics treated
in this chapter are: Significant Figures, Accuracy Data, Precision Data,
Report Forms, Digital Read-Out, Key Punch Cards and Paper Tape, Storet Com-
puterized Storage and Retrieval of Water Quality and Data and SHAVES - a
Consolidated Data Reporting and Evaluation System.
8-56
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CHAPTER 7
DATA HANDLING AND REPORTING
7.1 Introduction
To obtain meaningful data on water quality, the laboratory must first collect a
representative sample and deliver it unchanged for analysis. The analyst must then complete
the proper analysis in the prescribed fashion. Having accomplished these steps, one other
important step must be completed before the data are of use. This step includes the
permanent recording of the analytical data in meaningful, exact terms, and reporting it in
proper form to some storage facility for future interpretation and use.
The brief sections that follow discuss the data value itself, recording and reporting the value
in the proper way, means of quality control of data, and storage and retrieval.
7.2 The Analytical Value
7.2.1 Significant Figures
The term significant figure is used rather loosely to describe some judgment of the number
of reportable digits in a result. Often the judgment is not soundly based and meaningful
digits are lost or meaningless digits are accepted.
Proper use of significant figures gives an indication of the reliability of the analytical
method used. The following definitions and rules are suggested for retention of significant
figures:
A number is an expression of quantity. A figure or digit is any of the characters 0,1, 2, 3, 4,
5, 6, 7, 8, 9, which, alone or in combination, serves to express a number. A significant figure
is'a digit that denotes the amount of the quantity in the place in which it stands.
Reported values should contain only significant figures. A value is made up of significant
figures when it contains all digits known to be true and one last digit in doubt. For example,
if a value is reported as 18.8 mg/1, the "18" must be firm values while the "0.8 is
somewhat uncertain and may be "7" or "9".
The number zero may or may not be a significant figure:
a. Final zeros after a decimal point are always significant figures. For example, 9.8
grams to the nearest mg is reported as 9.800 grams.
b. Zeros before a decimal point with other preceding digits arc significant. With no
other preceding digit, a zero before the decimal point is not significant.
c. If there are no digits preceding a decimal point, the zeros after the decimal point
but preceding other digits are not significant. These zeros only indicate the position
of the decimal point.
8-57
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d. Final zeros in a whole number may or may not be significant. In a conductivity
measurement of 1000 /imhos/cm, there is no implication that the conductivity is
1000 ± 1 pmho. Rather, the zeros only indicate the magnitude of the number.
A good measure of the significance of one or more zeros before or after another digit is to
determine whether the zeros can be dropped by expressing the number in exponential form.
If they can, the zeros are not significant. For example, no zeros can be dropped when
expressing a weight of 100.08 grams in exponential form; therefore the zeros are significant
However, a weight of 0.0008 grams can be expressed in exponential form as 8 x IO'4 grams!
and the zeros are not significant. Significant figures reflect the limits of the particular
method of analysis. It must be decided beforehand whether this number of significant digits
is sufficient for interpretation purposes. If not, there is little that can be done within the
limits of normal laboratory operations to improve these values. If more significant figures
are needed, a further improvement in method or selection of another method will be
required to produce an increase in significant figures.
Once the number of significant figures is established for a type of analysis, data resulting
from such analyses are reduced according to set rules for rounding off.
7.2.2 Rounding Off Numbers
Rounding off of numbers is a necessary operation in all analytical areas. It is automatically
applied by the limits of measurement of every instrument and all glassware. However, it is
often applied in chemical calculations incorrectly by blind rule or prematurely, and in these
instances, can seriously affect the final results. Rounding off should normally be applied
only as follows:
7.2.2.1 Rounding-Off Rules
a. If the figure following those to be retained is less than 5, the figure is dropped, and
the retained figures are kept unchanged. As an example: 11.443 is rounded o'ff to
11.44.
b. If the figure following those to be retained is greater than 5, the figure is dropped,
and the last retained figure is raised by 1. As an example: 11.446 is rounded off to
11.45.
c. When the figure following those to be retained is 5, and there are no figures other
than zeros beyond the 5, the figure is dropped, and the last place figure retained is
increased by 1 if it is an odd number, or it is kept unchanged if an even number. As
an example: 11.435 is rounded off to 11.44, while 11.425 is rounded off to 11.42.
7.2.2.2 Rounding Off Single Arithmetic Operations
a. Addition: When adding a series of numbers, the sum should be rounded off to the
same numbers of decimal places as the addend with the smallest number of places.
However, the operation is completed with all decimal places intact and rounding off
is done afterward. As an example:
11.1
11.12
11.13
33.35 The sum is rounded off to 33.4.
8-58
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b. Subtraction: When subtracting one number from another, rounding off should be
completed before the subtraction operation, to avoid invalidation of the whole
operation.
c. Multiplication: When two numbers of unequal digits are to be multiplied, all digits
are carried through the operation, then the product is rounded off to the number of
significant digits of the less accurate number.
d. Division: When two numbers of unequal digits are to be divided, the division is
carried out on the two numbers using all digits. Then the quotient is rounded off to
the number of digits of the less accurate of the divisor or dividend.
e. Powers and Roots: When a number contains n significant digits, its root can be
relied on for n digits, but its power can rarely be relied on for n digits.
7.2.2.3 Rounding Off the Results of a Series of Arithmetic Operations
The rules for rounding off are reasonable for simple calculations, however, when dealing
with two nearly equal numbers, there is a danger of loss of all significance when applied to a
series of computations which rely on a relatively small difference in two values. Examples
are calculation of variance and standard deviation. The recommended procedure is to cany
several extra figures through the calculation and then to round off the final answer to the
proper number of significant figures.
7.2.3 Glossary of Terms
To clarify the meanings of reports and evaluations of data, the following terms are defined.
They are derived in part from American Chemical Society and American Society for Quality
Control usage (1,2).
7.2.3.1 Accuracy Data
Measurements which relate to the difference between the average test results and the true
result when the latter is known or assumed. The following measures apply:
Bias is defined as error in a method which systematically distorts results. The term
is used interchangeably with accuracy in that bias is a measure of inaccuracy.
Relative error is the mean error of a series of test results as a percentage of the true
result.
7.2.3.2 Average
In ordinary usage, the arithmetic mean. The arithmetic mean of a set on _n_values is the sum
of the values divided by.n.
7.2.3.3 Characteristic
A property that can serve to differentiate between items. The differentiation may be either
quantitative (by variables), or qualitative (by attributes).
8-59
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7.2.3.4 Error
The difference between an observed value and its true value.
7.2.3.5 Mean
The sum of a_series of test results divided by the number in the series. Arithmetic mean is
understood (X).
7.2.3.6 Population
Same as Universe. (See subparagraph 7.2.3.13).
7.2.3.7 Precision
Degree of mutual agreement among individual measurements. Relative to a method of test,
precision is the degree of mutual agreement, among individual measurements made under
prescribed, like conditions.
7.2.3.8 Precision Data
••
Measurements which relate to the variation among the test results themselves, i.e., the
'scatter or dispersion of a series of test results, without assumption of any prior information.
The following measures apply:
a. Standard Deviation (a). The square root of the variance.
a - w 1=1 Y 2
n
b. Standard Deviation, estimate of universe (s).
n-1
c. Coefficient of Variance (V)._The ratio of the standard deviation (s) of a set of
numbers, n, to their average, X, expressed as a percentage:
~
d. Range. The difference between the largest and smallest values in a set.
e. 95% Confidence Limits. The interval within which one estimates a given population
parameter to lie, 95% of the time.
8-60
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7.2.3.9 Sample
A group of units, or portion of material, taken from a larger collection of units, or quantity
of material, which serves to provide information that can be used as a basis for judging the
quality of the larger quantity as a basis for action on the larger quantity or on the
production process. Also used in the sense of a "sample of observations."
7.2.3.10 Series
A number of test results which possess common properties that identify them uniquely.
7.2.3.11 Skewness(k)
A measure of the lopsidedness or asymmetry of a frequency distribution defined by the
expression:
(Xj -X)3
This measure is a pure signed number. If the data are perfectly symmetrical, the skewness is
zero. If k is negative, the long tail of the distribution is to the left. If k is positive, the long
tail extends to the right.
7.2.3.12 Unit
An object on which a measurement or observation may be made.
7.2.3.13 Universe
The totality of the set of items, units, measurements, etc., real or conceptual, that is under
consideration.
7.2.3.14 Variable
A term used to designate a method of testing, whereby units are measured to determine, and
to record for each unit, the numerical magnitude of the characteristic under consideration.
This involves reading a scale of some kind.
7.3 Report Forms
The analytical information reported should include the parameter, the details of the analysis
such as burette readings, absorbance, wavelength, normalities of reagents, correction factors,
blanks, and finally, the reported value.
To reduce errors in manipulation of numbers, a good general rule is to keep data
transposition to an absolute minimum. If this were pursued, the ideal report form would
include all preliminary information of the analysis, yet it would be possible to use the same
form through to the final reporting of data into a computer or other storage device.
However, the ideal report form is not usually in use. Rather, a variety of methods are used to
record data. They are:
8-61
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7.3.1 Loose Sheets
Reporting of data onto loose or ring-binder forms is an older, but much used means of
recording data. It does allow easy addition of new sheets, removal of older data, or
collection of specific data segments. However, the easy facility for addition or removal also
permits easy loss or misplacement of sheets, mix-ups as to date sequence, and questionable
status in formal display, or for presentation as evidence.
7.3.2 Bound Books
An improvement in data recording is use of bound books which force the sequence of data
insertion. Modification beyond a simple lined book improves its effectiveness with little
additional effort. Numbering of pages encourages use in sequence and aids also in
referencing data, through a table of contents, according to time, type of analysis, kind of
sample, analyst, etc.
Validation can be easily accomplished by requiring the analyst to date and sign each analysis
on the day completed. This validation can be strengthened further by providing space for
the laboratory supervisor to sign off as to the date and acceptability of the analysis.
A further development of the bound notebook is the commercially available version
designed for research-type work. These note books are preprinted with book and page
numbers and spaces for title of project, project number, analyst signature, witness signature
and dates. Each report sheet has its detachable duplicate sheet which allows for up-to-date
review by management without disruption of the book in the laboratory. The cost is about
four times that of ordinary notebooks.
Use of bound notebooks is essentially limited to research and development work where an
analysis is part of a relatively long project, and where the recording in the notebook is the
prime disposition of the data until a status or final report is written.
7.3.3 Pre-Printed Report Forms
Most field laboratories or other installations doing repetitive analyses for many parameters
day in and day out, develop their own system of recording and tabulating laboratory data.
This may include bound notebooks; but a vehicle for forwarding data is also required. In
many instances, laboratory units tailor a form to fit a specific group of analyses, or to report
a single type of analysis for series of samples, with as much information as possible
preprinted to simplify use of the form. With loose-sheet multicopy forms (use of carbon or
NCR paper) information can be forwarded daily, weekly, or on whatever schedule is
necessary while allowing retention of all data in the laboratory. Still, the most common
record is 'an internal bench sheet, or bound book, for recording of all data in rough form.
The bench sheet or book never leaves the laboratory but serves as the source of information
for all subsequent report forms (See Figure 7-1).
In most instances the supervisor and analyst wish to look at the data from a sample point in
relation to other sample points on the river or lake. This review of data by the supervisor,
prior to release, is a very important part of the laboratory's quality control program;
however, it is not easily accomplished with bench sheets. For this purpose, a summary sheet
can be prepared which compares a related group of analyses from a number of stations. An
example is shown in Figure 7-2. Since the form contains all of the information necessary for
8-62
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' Figure 7-1. EXAlv 3F 13ENCH SHEET
NL-C-88
(1-68)
Spcctrographic Analyses Bench Data
Sample # Date Source.
Test Count
Sec
TDS.
ml. cone. to.
ml. Factor
3.,
Count
1. Zn
2. Cd
r Ac
d. R
«; p
fi Fe
7 Mn
R, Mn
0 Al
1 n III-.
1 ' , <"»
19 Ac
P Nj
14 Co
i <; Ph
16 Tr
]7 V
18. Rn
1Q. Sr
Rerun Count
PPM (pg/I)PPB
Av. In Cone. Less Orig.
Count Sample Than Sample
n
rn
! — i
1 ;
1
r~
r~
[j
i
1 1 !
n
m
n
1
i
rn
i
1
1 I
1 1 !
1
1
1 1
1 i
1 1
1 „
1 1
1 I
n r
i
I i
i i
i „
Mil
[— i r
i
i
I i
i
i „
00
ON
UJ
-------
Figure 7-2. EXAMPLE OF SUMMARY REVIEW SHEET
Table 2. MINERALS ANALYSES OF ZONE B, OHIO RIVER SAMPLES, CONC., mg/I.
STATION
Ohio at Ironton
Ohio at Greenup Dam
Ohio at Portsmouth
Scioto at Lucasville
Ohio at Maysville
Ohio at Meldahl Dam
Little Miami at Cincinnati
Ohio at Cincinnati
Licking at 12th Street
Ohio at Miami Fort
Ohio at Markland Dam
Kentucky nt Dam I
Ohio at Madison
Great Miami at Eldcan
Great Miami at Scllars Road
Great Miami at Liberty-
Fairfield Road
Great Miami at American
Materials 8 ridge
Whitewater at Suspension
Great Miami at Lawrenceburg
(Lost Bridge)
Storet
Number
200152
200001
200139
381710
200153
383070
380090
380037
200523
383072
200521
200522
174304
383047
383015
383007
383071
Date,
1969
Alkalinity
Hardness
Chloride
Sulfate
Fluoride
SOLIDS
Total
«
Diss.
Susp.
-------
reporting data it is used also to complete the data forms forwarded to the storage and
retrieval system.
The forms used to report data to data storage s>stems require a clear identification of the
sample point, the parameter code, the type of analysis used, and the reporting terminology.
Failure to provide the correct information can result in rejection of the data, or insertion in
an incorrect parameter. As a group of analyses is completed on one or more samples, the
values are reported in floating decimal form, along with ihe code numbers, for identifying
the parameter and the sampling point (station). Figure 7-3 shows an example of a preprinted
report form for forwarding data to keypunch.
7.3.4 Digital Read-out
Instrumental analyses, including automated, wet-chemistry instruments, such as Technicon
AutoAnalyzer, atomic absorption spectrophotometer. pH meter, selective electrode meter,
etc., now can provide direct digital readout of concent rat ion, which can be recorded directly
onto report sheets without further calculation. Electronics manufacturers now produce
computer-calculators that will construct best-fit curves. Integrate curves, and/or perform a
pre-set series of calculations required to obtain the final reported value for recording by the
analyst.
7.3.5 Key Punch Cards and Paper Tape
Since much of the analytical data generated in laboratories is recorded on bench sheets,
transferred to data report forms, key-punched, then manipulated on small terminal
computers, or manipulated and stored in a larger data storage system, there is a built-in
danger of transfer error. This increases with each transposition of data. It is suggested that
the analyst can reduce this error by recording data onto punch cards directly from bench
sheets. The cards can be retained, or forwarded immediately to the data storage system as
desired. IBM now offers a small hand-operated key-punch for this purpose.
It is anticipated that in future water quality systems, the intermediate report sheers will be
eliminated and the data will be punched automatically by the analytical instrument system
onto key-punch cards and/or paper tapes for direct use as computer input.
7.4 STORET-Computerized Storage and Retrieval of Water Quality Data
The use of computers with their almost unlimited ability to record, store, retrieve, and
manipulate huge amounts of data is a natural outgrowth of demands for meaningful
interpretation of the great masses of data generated in almost any technical activity.
In August 1961, an informal conference was held in the Basic Data Branch, Division of
Water Supply and Pollution Control, U.S. Public Health Service. A number of ideas were
brought together in the basic design of a system for storage and retrieval of data for water
pollution control, called STORET. In 1966, the STORET system was transferred, with the
Division, into the Federal Water Pollution Control Administration. U.S. Department of the
Interior. A refinement of this system is now operated by the Technical Data and
Information Branch, Division of Applied Technology. EPA.
If properly stored, the data can be retrieved according to the point of sampling, the date,
the specific parameters stored, etc., or all data at a sample point or series of points can be
8-65
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Figure 7-3. EXAMPLE OF STORE? REPORT FORM
• ATER QUALITY DATA
»T «tiQN C
LABORATORY BENCH DATA
••-•"•• YN." "nVrVAY
•"" ,..,.
1 1 1
Fccil Coliform UMIT MF/100
i 1 | 1 1 | 1 1 1 III
.Tt^ Fecal Streptococci umr MF/100
L-U-
LLi
ITfM _
LU
ITEM
1 1 1
•T*«.. .
1 1
LU
ITCH
LU
ITC-*
LU
ITCH
IU
LU
1 1 j 1 1 1 1 1 1 III
NHrN + Org-N UM1T mg/1
11)111111 III
NHj-N UHIT mg/1
1 1 j 1 1 I 1 1 1 III
NOj-N * NOj-N UNIT mg/1
1 1 | 1 1 1 I 1 1 III
P. Total UNIT ms/l
1 1 } i 1 J 1 1 1 III
P, Soluble UNIT mg/1
1 1 J 1 1 J I--I 1 III
TOC urfiT ma/I
1 1 j 1 1 II 1 1 III
Phenol uniTUe/l
1 1 ] 1 1 1 1 | I ,|||
Cyanide ' UNIT mit/1
1 1 | 1 1 1 1 1 1 III
COMPUTED CC3EOD»TA
ITATION COOI lIKl'l- T"
111 i i i i ; i
i : i
PAKAHITCH COOI VAklll
|3|<|6|l|6|| | | 1 1
h|.|6|7|9|| | | 1 1
|0|0|6|3|5|| | | | |
Io|o|6|,|o|
|0|0|6 3|0|| | | | 1
NEXT CARD . RBPtAT COLI.MHJ ;.II»50VE
|0|0|6 6|5|| | | 1 1
|0|0|6|6|6|| | | | |
|0|0|6|8|0|| | | 1 1
|3|2|7|3|0|| 1 I I 1
Io|o|7h|o|| | | | |
• I.TI n->i
i : i
i : i
ODD
DDD
DDD
ann
CHO.
DDDD
aan
ODD
DDD
ana
nnnn
7i . H •• •*
8-66
-------
extracted as a unit.
There is a State/Federal cooperative activity which provides State water pollution control
agencies with direct, rapid access into a central computer system for the storage, retrieval,
and analysis of water quality control information.
Full details on use of the STORET system are given in the STORET handbook recently
revised (3).
7.4 SHAVES-A Consolidated Data Reporting and Evaluation System
Information systems have been developed to bridge the gap between the analyst and his raw
data, and a complex data storage and control system. These systems include preprinted
report forms, computerized verification, and evaluation of data and data storage. An
example is the SHAVES system.
The term, SHAVES, is an acronym for "Sample Handling and Verification System," which
originated at the Great Lakes-Illinois River Basin Comprehensive Project Laboratory at
Grosse Isle, Michigan. Although the system's original purpose was verification of the
calculations following laboratory analyses, it now includes data storage, checks for
completeness and consistency of data, procedures for submitting analytical requests, a set of
forms for recording sampling and analytical information, and a clerical procedure to account
for analyses completed and pending. The primary purposes of SHAVES are the
standardization, automation and control of reporting analyses. All samples received at the
Pacific Northwest Water Laboratory for routine analysis are processed through the system.
Although SHAVES uses a computer to perform its operations, it is not primarily a computer
program. It is intended for use as an intra-laboratory quality control tool, and as such
compliments the STORET system. It is described in detail elsewhere (4).
7.6 References
1. "Guide for Measure of Precision and Accuracy," Anal. Chem., Vol. 33, p. 480, (1961).
p. 480.
2. "Glossary of General Terms Used in Quality Control," Quality Progress, Standard
Group of the Standards Committee, ASQC, II, (7), pp. 21-2, (1969).
3. Water Quality Control Information System (STORET), EPA, Washington, D.C. 20460,
Nov. 15,1971.
4. Byram, K. V. and Krawczyk, D. F., "An Evaluation of SHAVES: A Water Quality
Sample Handling System," Environmental Protection Agency, Pacific Northwest Water
Laboratory, 1969.
8-67
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9. STEP OUTLINE OF MONITORING PROCEDURES
p.**
9.1 INTRODUCTION
For every landfill both existing and proposed, the necessity
of establishing a ground-water monitoring program should be
investigated. The methodology to make this determination and,
if necessary, to define the specifics of a monitoring program,
can be described in a logical sequence of individual steps.
Following the generalized steps ""presented in this chapter will
allow these determinations to be based on the proper factual
information. As with any complex situation, however, original
thought will be required during each step to insure arriving
at the best possible answers.
The steps presented in this chapter are intended to indicate
the logical progression of required efforts and therefore not
accompanied by detailed descriptions. Such descriptions can
be found in other chapters of this manual or in the references
cited at the end of the appropriate chapter.
9.2 STEP 1 - INITIAL SITE INSPECTION
All the information would be gathered from an inspection of the
landfill, examination of landfill records and other existing
information such as topographic maps, and discussion with land-
-------
fill operating personnel. The purpose is to define, with a
mininum expenditure of time and money, the probable magnitude
of the ground-water contamination problem and thus the urgency
of conducting a detailed study and establishing a monitoring
program.
9.2.1 NATURE OF THE WASTE
The types of waste accepted or rejected varies widely from
landfill to landfill depending largely on the types of waste
generated in the area, the regulatory agency for the area, the
landfill operator, and economics. A determination of the
types of wastes accepted at a particular landfill (both current-
ly and historically) is critical to the monitoring evaluation,
i.e., the contaminants likely to be present in the ground water.
Wastes can be generally categorized as follows:
- municipal refuse (paper, household garbage, leaves and
grass, wood, synthetics, cloth, glass and metal)
- bulky refuse (tree stumps, car bodies, and demolition
debris)
- municipal sewage sludge
- industrial solid wastes (defective raw materials and prod-
ucts, packaging and scrap)
- industrial chemical wastes (liquid or solid)
-------
- industrial sludge or residue (fly and bottom ash, waste
water treatment sludge and pollution control systems
residue) •''
- chemical waste in sealed drums (of particular concern
because of delayed release factor)
- low level radioactive wastes (contaminated laboratory
equipment/ clothing and building debris)
The categories which are accepted at the landfill should be
determined and/ in the case of Industrial wastes, more detailed
information should be sought.
9.2.2 AREAL EXTENT AND THICKNESS OF THE LANDFILL
The size and thickness of a landfill are important factors in
establishing the volume of leachate generated as well as the
concentration of contaminants in the leachate. The areal ex-
tent of a landfill may be measured directly or indirectly
from an accurate large scale map or aerial photograph. In
addition, the extent of flat and sloping portions of the land-
fill should be determined. Landfill thickness may, in some
cases, be determined from a recent topographic map or by
measuring the difference in elevation between the toe and top
surface. If the landfill fills a depression, pre-landfilling
elevations of the base of the depression may be available,
-------
otherwise one or more borings will have to be drilled through
the landfill to directly determine its thickness.
9.2.3 PRETREATMENT AND IN-PLACE TREATMENT OF REFUSE
In most cases, refuse is compacted after it has been placed
in the landfill. This is accomplished either by special equip-
ment or by the bulldozers used to spread and cover the refuse.
The method of in-place compaction should be determined to allow
estimates to be made of density and field capacity of the land-
fill. In some cases refuse receives treatment prior to land-
»
filling. Shredding and/or pre-disposal compaction and baling
of refuse will significantly increase its density and thus its
field capacity. Incineration and resource recovery operations
will alter its composition and consequently change the nature
of the leachate generated after landfilling. In addition, the
percentage of the total refuse received which is treated, the
types of refuse receiving treatment and the placement of the
treated and untreated refuse in the landfill should be deter-
mined.
9.2.4 LANDFILLING PROCEDURES
The procedures used in placing and covering refuse at the land-
fill site will influence the volumes and characteristics of
leachate generated. Such practices as separation of different
types of refuse at the landfill site, thickness of refuse
-------
layers between cover layers, thickness of cover layers, and
type of material used for cover will be of importance. For
f
.•
example, if chemical wastes are accepted at a landfill but
segregated from municipal refuse in one area, leachate gen-
erated within this chemical disposal area will follow a flow
-i
path which may be predictable and thus would influence the
selection of monitoring points. Thickness of refuse and
cover layers may affect volumes and characteristics of
leach'ate and would therefore also influence the design of a
monitoring system. ;
9.2.5 RATE OF LANDFILLING AND REFUSE AGE
The rate at which the thickness of a landfill increases will
affect the volume of leachate generated since a thick section
of refuse can absorb more water (field capacity) . If the land-
fill thickness increases at a sufficient rate relative to pre-
cipitation, and is covered upon completion to exclude precipi-
tation, very little leachate will be generated. Thus, the rate
of filling will influence the design of a monitoring program.
The rates of increase in thickness of various portions of the
o
landfill may be extraplated from the records of weights of
A
refuse accepted over the landfilling period, if such records
are available. If not, recollections of landfill operators re-
garding volumes of refuse accepted over past years may provide
-------
some useful information.
Refuse layers of different ages produce leachates of different
««
chemical characteristics. This factor may be useful in design-
ing a monitoring program; however, other factors, such as refuse
composition have a more noticeable influence on leachate than
does refuse age.
9.2.6 LINERS AND COVERS
A landfill equipped with an underliner and leachate collection
system would be assumed not to be contaminating ground water
and a monitoring system would be designed only to test the
validity of this assumption. Similarly, if the landfill were
completed and covered to prevent the infiltration of precipita-
tion, monitoring, at least initially, would be necessary only
to establish if this were indeed the case. If the liner or
cover system was shown to be ineffective by initial monitoring
data, an expanded monitoring program would be designed to define
the extent of the problem and necessary corrective measures.
When analyzing the effectiveness of a bottom liner and collec-
tion system, the volume of leachate actually collected should
correspond to the predicted volume of leachate being generated.
With covers and surface drainage systems, runoff and evapo-
transpiration accounts for a large percentage of precipitation.
Factors such as cover permeability, slopes and vegetation type
-------
would be considered in this determination.
9.2.7 VISUAL SURVEY OF TOPOGRAPHY AND GEOLOGY
The primary purpose of this effort would be to establish
estimates of surface runoff and infiltration patterns, and
general direction of ground-water flow. The topography of
the areas surrounding the landfill will establish the direc-
tion of surface-water flow, either towards or away from the
landfill surface. Recharge and discharge areas at the site
can be determined and, based on_these, the general direction
of ground-water flow approximated.
9.2.8 GROUND-WATER USE (PRELIMINARY)
A preliminary check into ground-water use in the vicinity of
the landfill should be made at this time. Simply ascertain-
ing the existence of supply wells in the vicinity of the land-
fill is sufficient for this step, with additional data regard-
ing such wells obtained as part of the next step.
9.3 STEP 2 - PRELIMINARY INVESTIGATIONS
Once the need for a detailed ground-water investigation and
monitoring program has been established (Step 1), the program
should be carefully planned. To accomplish this task efficient-
ly, all existing pertinent data is gathered and examined at the
outset. The data would include all information from Step 1 and
-------
any useful data available fron outside sources. In addition,
certain data not gathered during Step 1, but which can be
*•
readily obtained at the site, e.g., analyses of water samples
from existing wells, are now gathered.
9.3.1 EXISTING DATA
Information which should be sought other than that gathered
in Step 1 includes: historical precipitation records for the
site or a nearby area, geologic and topographic maps which
include the landfill site, geologic logs of any existing wells
or test borings at or near the site, and a recent aerial
photograph of the site from which to prepare an accurate base
map. In addition, if potential sources of contamination other
than the landfill are located in the vicinity, all available
information regarding these sources (type and volume of waste,
methods of disposal, etc.) should be collected and reviewed.
9.3.2 PRELIMINARY SITE INVESTIGATION
Additional data which will improve the efficiency of a hydro-
geologic investigation of a landfill (Step 3) include: analyses
of water samples from surface-water bodies and existing wells
located on or near the site; analyses of samples of leachate
from surface seeps; examination of site vegetation, by a
Dotpnist, for signs of stress; observations of surface drainage
-------
patterns during a rainfall; and a check of building base-
ments and other subsurface structures at the site for landfill
gas accumulations. ""
The most critical areas for monitoring in the vicinity of a
landfill will be where industrial, domestic, or public-supply
wells are threatened by leachate contamination. In the pre-
vious step, a preliminary check of the number and location of
all such wells was made. In addition to well locations, such
information as screened interval, pumping rates and periods of
pumping, as well as water use Should be compiled. If possible,
•the size and shape of the cone of influence should be estimated
for each well located. Historical water-quality data for the
wells, where available, should be examined and, where not
available or insufficient, water samples should be taken for
analyses.
Many states and regional authorities have regulations regarding
minimum distances from landfills within which supply wells must
be monitored for contamination. These regulations would have
to be followed, but the actual distance monitored should be
based on the results of a hydrogeologic investigation. Con-
stituents determined in water-quality analyses should meet
applicable regulations and expanded, if necessary, based on
anticipated leachate characteristics and ultimate use of water
from each supply well.
-------
Besides supply wells, surface-water use in the area must be
considered. Nearby surface water may bo used for potable
supply, fishing or shellfishlng, swimming or other recreation,
or wildlife habitat. Surface-water bodies are often discharge
areas, and as such are subject to contamination from leachate
in the ground-water system. 'Such information as location, use
and rate of flow for all surface-water bodies in the vicinity
of a landfill should be established. Natural water quality,
existing contamination, and sources of contamination should
be investigated. Surface-water bodies may form an important
part of a monitoring program because, at discharge points,
they are the places where ground-water contamination is most
conspicuous.
9.4 STEP 3 - DEFINITION OF THE HYDROGEOLOGIC SETTING
Probably the most important factor in establishing the need
for and design of a landfill monitoring system is the hydro-
geologic setting of the landfill. Such information as surficial
and bedrock geology, depth to the water table and direction and
rate of ground-water flow should be determined prior to se-
lecting a landfill site. In the past this has not been the
case and landfills have been located primarily on land of low
economic value, such as swamps or abandoned gravel pits. In
such areas the ground-water pollution potential is high and
the need for monitoring and abatement procedures is acute.
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9.4.1 SURFICIAL GEOLOGY
A survey of surficial geology should establish the areal extent
and thickness of the layers of various types of deposits under
and adjacent to the landfill, and the permeabilities and inter-
connections of these layers. The survey can be divided into
three sequential parts: 1) a review of geologic data gathered
during Steps 1 and 2; 2) geophysical surveys designed to fill
in missing subsurface information; and 3) test drilling to
provide direct control for the geophysics, obtain more precise
•
data in critical areas, and allow detailed analyses of geologic
samples.
9.4.2 BEDROCK GEOLOGY
In some cases bedrock will act as a barrier to leachate move-
ment and in others leachate may move into bedrock aquifers.
The type of rock beneath the site and the amount of fracturing
will determine the role of bedrock in the movement of leachate.
Determination of bedrock geology will essentially follow the
Ji
steps outline for surficial geology.
/)
9.4.3 GROUND WATER
The ground-water investigation should be designed to answer
such questions as depth to the water table, extent of ground-
water mounding caused by the landfill, natural flow direction
-------
and rate, influence of the landfill on flow direction and
rate, locations of recharge and discharge areas, types and
interconnection of aquifers, and infiltration at the site
relative to total ground-water flow. Much of this information
will be obtained during and immediately following the pre-
viously outlined geologic investigation. During test drill-
ing, such data as water levels and head differences with in-
creasing depth would be recorded. Test borings can be equipped
with screens and test pumped at various intervals, using other
borings as observation wells, to establish aquifer character-
istics and interconnection between aquifers.
Historical precipitation records and estimation of surface
runoff and evapotranspiration will provide information regard-
"TViese- £\
-------
the best locations and depths of monitoring wells. The size
and complexity of a monitoring progra.ii will be partially based
on the calculated volume of recharge through the landfill, and
the volume and rate of ground-water flow. Subsequent steps
in this chapter will provide data necessary for refinement of
••i
the initially outlined monitoring program and elimination of
its less important features.
9.4.4 DETERMINE EXISTING WATER QUALITY
An accurate and complete record of existing water quality,
both ground and surface, is very useful in a monitoring program.
If contamination has already occurred, water samples from un-
contaminated areas should be collected and analyzed to estab-
lish natural water quality. If sources of contamination other
than the landfill are present, the effects of these sources
should be determined. Since the object of a monitoring pro-
gram is to determine change, the importance of historical
data is obvious.
If sources of contamination other than the landfill are present,
(determined in Step 2) and if existing information is insuffi-
cient to define the problem, additional investigation will be
necessary. Such an investigation would include direction of
ground-water flow in the vicinity of the source, rate of con-
taminant generation, nature of the contaminants, and result-
-------
ing degree of ground-water degradation. The monitoring sys-
tem must then be designed to account for these "outside" con-
/
taminants, so that they, or their effects, are not inadver-
tently attributed to the landfill.
In addition to directly introduced contaminants, landfill
leachate may cause secondary reactions to occur when it
reaches and blends with ground water. For example, a mixing
of chemically reduced leachate with ground water may lower
the oxidation potential of the leachate-enriched ground water.
This, in turn, may reduce and dissolve iron or manganese
occurring in the aquifer materials as coatings. Cation ex-
change reactions which release calcium and magnesium, changes
in pH, or precipitation of some leachate constituents are
other reactions which could occur and change water quality.
9.4.5 DETERMINATION OF THE RATE OF LEACHATE GENERATION
The leachate generation rate, which will influence the extent
of the necessary monitoring program, is determined by a water
balance study of the landfill. Data necessary for water bal-
ance determination include: precipitation data, landfill
surface characteristics, vegetation type and density, land-
fill site topography, ground-water underflow rate, rate of
landfilling and pretreatment and compaction of refuse. A dis-
cussion of water balance calculations is given in Chapter 5
of this manual.
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9.5 STEP 4 - DETERMINE THE POLLUTING POTENTIAL OF THE LANDFILL
The extent and design of a npnitoring system will be largely
determined by the pollution potential of the landfill. Esti-
mation of the pollution potential is essentially by consolida-
tion of all data gathered in,Steps 1, 2 and 3. Determinations
made would include: the location, size and rate of movement
of the contaminated plume; the aquifers affected and those
which may be affected in the future; the types of contaminants
present, and the degree of attenuation of those contaminants
by the subsurface sediments. Ttaie data can then be used to —
predict the total pollution damage that may be caused by the
landfill if no action is taken, or to estimate the influence
of various possible abatement procedures. Monitoring program
data SJT then used to establish the accuracy of these predictions
or provide a warning of abatement system ineffectiveness or
failure.
9.6 STEP 5 - ESTABLISH THE MONITORING PROGRAM
The information gathered in the previous steps would now be
written into a detailed report describing the investigations
and defining the ground-water contamination problem at the
landfill site. Based on this report, the monitoring system
would be designed. The methods and purposes for such a moni-
toring program are outlined below, with detailed discussions
of the various topics included in other chapters of this manual.
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9.6.1 SELECT THE MONITORING SITES
Data from the previous steps is used to rank all potential
/
monitoring sites in order of importance. High priority sites
would include currently developed aquifers, aquifers with good
development potential, and discharge areas, such as marshland,
i
which could be damaged by the anticipated leachate discharges.
Monitoring sites should be selected to provide sufficiently
early warning to allow corrective action to be taken. Ideally,
monitoring should be sufficient to indicate the size and type
of abatement program necessary .to correct a problem once it
has been detected. At the very least, the monitoring program
should insure that a health hazard does not arise.
9.6.2 DETERMINE MONITORING OBJECTIVES
Following selection of the sites to be monitored the specific
objectives of the monitoring program should be determined.
Such objectives might include: defining the rate of leachate
plume movement, monitoring the concentration of a specific
contaminant(s), early warning of an unexpected change in di-
rection or enlarging of the leachate plume, or unexpected inter-
aquifer movement of the plume to a previously unpolluted
aquifer.
Once the monitoring objectives have been determined, the data
requirements to satisfy these objectives must be defined.
-------
Data requirements would include: specific chemical constitu-
ents to be included in analyses of water samples, physical
measurements to be made on dite, and the frequency of sampling
or measurement. For example, if an objective of a monitoring
program is to insure that leachate does not migrate into a
particular aquifer, monthly measurements of the specific con-
ductance of water samples from that aquifer might be made, with
routine detailed chemical analyses run only on a semi-annual
or annual basis. Such a program might be selected to provide
information to protect the aquifer at minimal cost.
9.6.3 ESTABLISH THE MONITORING METHODS AND PROCEDURES
NECESSARY TO ACCOMPLISH OBJECTIVES
Certain monitoring devices will be required to accomplish the
specific monitoring program objectives. For example, at a
specific point, a single well screened over a small section of
an aquifer may suffice, or a cluster of several wells, screened
over different portions of the aquifer or in separate aquifers
may be required. Wells of a particular material may be neces-
sary to avoid interference with leachate sample chemistry, or
devices other than wells might be required. A discussion of
monitoring and sampling techniques is given in Chapter 5.
A detailed sampling or measuring procedure should be established
to insure uniform results. If possible, one person should be
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responsible for sampling or overseeing the sampling to insure
uniform procedure. This would be espeecially important for
complex procedures but less -'so for simpler procedures such as
conductance measurements. The handling and storage of water
samples is also extremely important. For example, if nitrogen
analyses are to be made, chilling or acidification of the
sample is required, and if metals are to be tested, acidifica-
tion with nitric acid is necessary. A discussion of preserva-
tion of samples is given in Chapter 7. The cost of monitoring
will vary widely depending on the sampling procedures and
analyses used, thus the program should be designed to be prop-
erly operable within the available budget.
Sufficient budget must also be reserved for proper data re-
duction, record keeping and periodic data review. Records of
data should be in three forms: the original data as gathered
along with explanatory notes, continuous tabular form, and
continuous graph form. Plotting data on approximately uniform
•fo \oe.
grids permits relative values and trends easily distinguishable.
^
Periodic review of all data by a qualified scientist followed
by a written summary, and distribution and review of the summary
cvfe- s
by all involved parties is- the proper procedure for handling
monitoring data.
9.6.4 ESTABLISH MANAGEMENT PROGRAM
Conditions under which abatement procedures, other corrective
-------
measures, or additional monitoring steps will be taken, should
be outlined at the outset of monitoring. Such conditions
might include constituent limits, physical parameter limits,
or trend shifts. Possible steps which might be taken in the
event the established conditions are exceeded should be de-
termined. An understanding should be reached as to where the
responsibility lies for all phases of the monitoring and poten-
tial abatement programs.
9. 7 EXAMPLES OF LANDFILL CONTAMINATION PROBLEMS
Following are two scenarios of fictitious landfill investiga-
tions leading to ground-water monitoring programs. The condi-
tions of the two investigations are somewhat different, the
first starting with a landfill and defining the pollution
problem, and the second starting with a problem and looking
for its cause. The first scenario closely follows the preced-
ing step outline; however, the second is an example of a prob-
lem requiring a somewhat different approach. The scenarios
are intended as illustrative examples and as such are neces-
sarily simplified, i.e., some points included in the step out-
line have been omitted. Approaches and conclusions other than
those presented may be equally valid, as no attempt has been
made to include all possibilities. Rather, it is left to
the reader to expand upon the two cases using the factual in-
formation presented in the other chapters of this manual.
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9.7.1 SCENARIO 1 - A LANDFILL CONTAMINATION STUDY
A large county maintained landfill is found to be in viola-
•;
tion of the 1899 Harbors and Rivers Act allowing leachate to
flow into and contaminate an adjacent river. As a result of
a Federal lawsuit, a court order is issued ordering county
i
officials to take the necessary steps to abate this condition.
The county officials retain a ground-water consulting firm
to investigate leachate conditions at the landfill site, de-
termine if leachate is actually discharging to the river, and
if so, what steps to take to abate this problem.
The hydrogeologist assigned this project makes a visit to the
landfill for a preliminary inspection tour with the landfill
operator. During this tour, he learns that the landfill re-
ceives approximately 1,000 tons of refuse per day, about 90%
of which is municipal; the remaining 10% is of industrial
origin. The refuse receives no pretreatment but after land-
filling, it is spread into thin layers by a bulldozer, and
compacted by a specially designed landfill compaction machine.
The layers of compacted refuse are covered daily by sandy fill
material. Small amounts of industrial chemical waste are
accepted at the landfill but it is not separated from the
other refuse. The rate and method of landfilling, the type
of cover material used, and local precipitation rates, indicate
that the refuse has all reached field capacity.
-------
The landfill is 40 acres in size and is approximately 60 feet
thick with a generally flat top surface. Directly north of
the landfill is a hill with*an elevation of approximately 80
feet. South of the landfill is a tidal marsh which separates
the landfill from the river. The distance between the land-
fill and the river is approximately 1,000 feet. The landfill
is not lined or covered with impermeable materials nor does
it utilize any other leachate prevention techniques.-
The topography of the site indicates to the hydrogeologist
that ground-water flow is from jaorth to south with the hill
and landfill acting as recharge areas, and the marsh and river
as discharge areas. The nearest supply well is located
approximately one-half mile north of the landfill and serves
as a supply well for an individual residence. No other wells
or borings SS/'be l^*i in the landfill vicinity.
The landfill has been in existence for approximately 12 years.
There was no special site preparation prior to landfilling;
refuse was simply dumped into the edge of the marsh. There
is presently little or no vegetation apparent on most of the
landfill surface and erosion channels on the steeper slopes
are apparent. Snail leachate seeps are evident along most
of the top of the landfill. These flow directly into the
marsh forming leachate pools which are periodically flushed
out into the river during periods of heavy rainfall. A sketch
-------
map prepared by the hydrogeologist during his field inspection
and showing important features of the landfill site is shown
on Figure /
During his discussion with the landfill operator, the hydro-
geologist learns that the county is considering the construc-
tion of a berm, or dike, around the southern toe of the land-
fill to prevent leachate from migrating into the marsh area.
County officials feel that leachate can be trapped behind
such a berm and pumped to an evaporation pit or back to the
top of the landfill for recircuj.ation. The hydrogeologist is
asked to evaluate the effectiveness of this scheme.
Additional observations by the hydrogeologist include the fact
that the flat, highly permeable top surface of the landfill
would allow a large percentage of precipitation to percolate
into the refuse. In addition, surface runoff from the hilly
area to the north is free to flow onto the top surface of the
landfill and infiltrate into the refuse. The volume of leach-
ate likely to be generated from these two recharge sources
would be considerably greater than the volume discharged by
the surface seeps. Thus, a considerable volume of leachate
must be moving with the ground-water system beneath the land-
fill and discharging into the marsh or river. If this is the
case, a surface berm would do little to abate the problem.
Final observations of the tour include the obvious stress on
-------
-------
vegetation in portions of the marsh directly south of the
landfill. However, there is no visible effect of discharging
leachate on the river.
,•
Based on his preliminary investigation, the hydrogeologist
recommends a detailed ground-water investigation to determine
if contaminated ground water is actually discharging directly
into the river and if so, the nature of the contaminants and
the rate of their discharge. In addition, he states that in
this case, the construction of a berm may do little to abate
leachate discharge to the river if it is in fact occurring.
*
The results of the ground-water study, however, will suggest
what other abatement steps might be more effective.
After being advised to proceed with the ground-water investi-
gation, the hydrogeologist obtains the following:
1. Precipitation records for the past three years from a
weather station located twelve miles from the landfill site.
2. A U.S. Geological Survey geologic map showing bedrock and
overburden materials in the vicinity of the site.
3. Information regarding the depth and construction of the domes-
tic supply well north of the landfill.
4. A water sample from the domestic supply well.
-------
5. Water samples from the river both upstream from and ad-
jacent to, the landfill.
6. A sample from one of the leachate seeps.
7. A recent aerial photograph of the site.
Analysis of the data gathered indicates that precipitation on
the landfill surface averages approximately 40 inches per
year. The hydrogeologist then estimates that a minimum of
50% of this precipitation infiltrates the surface of the land-
fill. Since the landfill area »is 40 acres, at least 20 million
gallons per year of leachate is generated from this source.
The low permeability crystalline bedrock which underlies the
site probably acts as a barrier to leachate flow. Details re-
garding the nature of the surficial materials at the landfill
site are not available. The domestic supply well north of
the landfill was drilled to a depth of 100 feet and screened
in a coarse sand aquifer with a high yield. Water from this
well shows no indication of leachate contamination, nor do any
of the water samples taken from the river. The seep sample,
however, is highly mineralized and contains contaminants
typically found in municipal refuse leachate. A base map of
the landfill site is traced from the aerial photograph.
To further define the location of contaminated ground water
at the landfill site, an electrical resistivity survey is
-------
conducted. The results of this survey, shown on Figure 3. ,
indicate that highly mineralized ground water is confined
to an area of the marsh directly south of the landfill. Some
attenuation of contaminants in the ground water appears to be
occurring in the direction of the river.
While the results of the resistivity survey indicate that con-
taminated ground water is indeed flowing from the landfill to
the river, additional geologic and water-quality data are
A
needed to further define the problem and suggest effective
abatement procedures. To obtain this information, a well
drilling contractor is hired to install a series of test bor-
ings and wells. Subsequently, five test borings are drilled
on and to the north of the landfill. Two casings with well-
points are installed in each boring. The locations of these
borings, designated A through E for the deep wells and A1 and
E for the shallow wells, are shown on Figure 3 . As the
drilling rig cannot be operated in the marsh area, ten addition-
al test wells are installed in this area by hand. The loca-
tions of these wells, designated 1 through 10, are also shown
on Figure 3 .
Construction details along with ground-water elevations, tem-
perature and specific conductance of ground water for all the
wells installed are shown on Table / . Based on tfcia^data, a
water-table contour map and geologic cross section are drawn
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U^r.«,
fr_
JL * L -f,^ t, ^^e*-
IOS-Q
'r... a*...—
-------
-=*r?o-i
. • >£^3
A » f1-"' ifl
— LU U J /[«./ ''fc*
rt _
-------
•f o // • — J T
-------
s
I!
(Figures -7 and *> respectively) . Also shown on Figure
is the ground-water head at each well point. As ground water
rv\o-jas ..
fJLow* along flowlines from areas of higher head to areas of —
lower head, examination of the figures shows that highly con-
taminated ground water from the base of the landfill is flow-
ing downward ir.co the deeper sediments beneath the landfill
and then upward and discharging directly into the river. This
analysis is supported by the specific conductance and tempera-
ture data.
While some attenuation of contaminants is occurring along the
flow path, the attenuation is by no means complete. Detailed
chemical analyses of water samples from all the test wells
(not given here) confirms this. In addition, contaminated
ground water from portions of the landfill is discharging di-
rectly into the marsh (Figure 5" ) and probably responsible for
for the observed vegetation stress. Figure -*>' also shows
contaminated water discharging directly to the river. The di-
lution is so great, however, that this source of contamination
is not detectable in river water samples.
Possible actions that might be considered with regard to this
problem are as follows:
1. Do nothing.
2. Remove the landfill to a more hydrologically acceptable site
-------
iU £^4-,o
-------
3. Construct a shallow surface berrt\ around the toe of the
landfill.
4. Install pumping wells directly beneath the landfill to
reverse the hydraulic gradient.
5. Install a line of interceptor wells along the toe of the
landfill to restrict movement of leachate away from the
landfill toward the river.
6. Reduce leachate generation by restricting recharge to
the landfill.
The first possibility is unacepptable because of the severe
stress placed on the marsh by the discharging leachate. The
second possibility is prohibitively expensive and the third
possibility would do little or nothing to abate the problem
due to the deep migration of the leachate. The fourth and
fifth possibilities may be technically feasible, but would be
difficult to accomplish due to the low permeability of the
sediments beneath the landfill. In addition, these two solu-
tions create the new problem of what to do with the large
volume of contaminated water pumped from the wells. The
final possibility appears to be the best solution and is so
recommended to the county.
The procedures recommended to reduce infiltration and thus
-------
leachate generation are as follows:
1. Close the landfill to duniping as soon as an alternate
*
site can be located. Prepare the new site using the
latest technology to reduce environmental impact.
2. Immediately eliminate runoff onto the landfill surface by
means of a cutoff trench and drain the collected uncon-
taminated runoff directly into the marsh for its beneficial
flushing action.
3. When the landfill is closed*to further dumping, regrade
the landfill surface to eliminate its presently flat top
surface and create a continuous grade from the top of the
hill to the toe of the landfill at the marsh (see Figure
4. Cover the entire landfill surface with a compacted soil
of low permeability. Cover this compacted material with
a layer of top soil and plant a high water use grass
species such as alfalfa.
5. Construct a series of swales and channels to further in-
crease surface runoff, reduce erosion and direct the
surface runoff into the marsh beyond the toe of the land-
fill (see Figure £. ) .
In addition, the consultants recommend that the county insti-
tute a monitoring program to determine the effectiveness of the
v
\ '
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M
i«rv>
\
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abatement plan. It is recommended that the monitoring data
collection begin as soon as possible to obtain antecedent in-
formation prior to making the abatement improvements on the
complete landfill.
The recommended program is as follows:
1. Install monitoring wells of the same design as Well 2 at
the two locations marked X on Figure *- . Use these,
plus the 15 existing test wells as monitoring wells.
2. Measure the water level in "each well monthly.
3. Measure the specific conductance of the water in each well
monthly.
4. Take a water sample from each well yearly and conduct a
detailed chemical analysis of each sample.
5. If any well shows a marked change in specific conductance,
analyze a water sample from that well immediately.
6. Install a rain gauge on the landfill surface and record
monthly precipitation.
7. Reduce all data to both tabular and graph form.
8. Review all data annually and, if necessary, adjust the
monitoring program as suggested by the data analyses.
V.
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9.7.2 SCENARIO 2 - A GROUND-WATER CONTAMINATION PROBLEM
For -.:-to months, a growing nipber of complaints have been
registered by residents of a housing development at the
northern edge of a small city. So far, eight citizens from
the development have visited., the Board of Health to complain,
each with the problem that something has suddenly gone wrong
with their drir.king water.
The city sanitarian sends an inspector to investigate the
eight complaints. He returns with the following report. In
two of the houses, slightly reddish water comes from the fau-
cets, even after running for prolonged periods. In a third
house, the water is slightly gray. The remaining houses are
not experiencing discoloration, but the water has a peculiar
taste and there is a slight odor apparent in the water of
some of the houses he visited.
The inspector has collected a water sample from each house,
directly from the kitchen sink as none of the houses are using
water softeners. The water samples are sent to a laboratory
for analysis. Meanwhile, the sanitarian marks the location
of each of the.affected houses on a map. He notes that each
house is connected to the city sewer system, but each has its
own water-supply well. All of the houses where the problem
has occurred are in the northern half of the development, and
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within an area a quarter-mile wide. Dozens of other houses
are interspersed with the ones inspected and each has the same
type of water supply and waste disposal system.
Only two possible causes of the water-quality problems are
apparent. The more likely of the two is that the 10-year old
sewer system has suddenly developed several large leaks and
the raw sewage is seeping into the ground and contaminating the
wells. The second, and seemingly more remote, potential cause
is the 45-acre county landfill located more than a mile north
of the nearest affected house. : The landfill seems even more
unlikely when the topography of the area is considered. As
shown an ffiijuiu .7 , ^torth of the development the terrain
rises gently for several hundred yards and is then broken by
a steep, elongated hill, which blocks a view of the landfill
from the city. Beyond the hill, the ground slopes gently
downward for more than half a mile to the edge of the landfill,
located in an old gravel quarry.
Thus, for contaminated water from the landfill to reach the
northern development, the sanitarian concludes it would have to
travel in an uphill direction for over a mile. If this were
the case, why weren't the houses affected sooner, as both they
and the landfill have been there for ten years. In addition,
why were only a few houses in the development affected and not
the others? And what about the four houses located north of
-------
the hill, between the development and the landfill, shouldn't
they be affected if the landfill were the cause? In an effort
to define the problem, the sanitarian sends his inspector to
obtain water samples from several additional houses in the de-
velopment where no problem had yet been reported and also from
two of the four houses between the landfill and the development.
When the results of the water analyses came back from the lab
they did little to indicate the source of the problem. Each
of the original eight samples, taken from houses where the
owners had complained, contained constituents well above the
recommended limits. The constituents in highest concentra-
tions were not the same for each house, however. Three of the
houses have water supplies with abnormally high iron content
and low pH. In all of the samples, chloride is well above
normal for the area, but the concentrations differ from sample
to sample. Significantly, concentrations of calcium and sodium
are abnormally high in two samples and manganese in one. Am-
monia is found to be above normal in five of the samples. The
analysis of the three samples from the houses in the develop-
ment whose owners had not complained, and the two samples from
outside the development indicated the wells at these locations
are producing high quality water.
The levels of chloride and metals in several of the samples
were too high to have originated from the sanitary sewer. In
-------
addition, the high-quality water in other houses in the de-
velopment would be unlikely if large leaks had developed in
the sewer line. On the other hand, the landfill is more than
a mile away, downhill from the development, and high-quality
water is being pumped from wells between the landfill and the
development so the landfill ..still seems an unlikely cause of
the problem. The sanitarian now believes that some completely
unknown source is responsible and decides to hire a ground-
water expert to determine what it is.
A ground-water consulting firm.is retained by the city, pre-
sented with the analyses of water samples from the thirteen
houses along with a map showing the location of those houses,
and charged with locating the source of the contaminants
apparent in eight of the samples.
The hydrogeologist assigned the task first obtains topographic
maps and geologic maps of the area from the U.S. Geological
Survey. In addition, he contacts a company providing aerial
photography services in a city nearby and is able to obtain
black and white aerial photographs of the city and the region
to the north. A visit to the local Health Department provides
well records for the houses in the affected development.
These records indicate the depth of each well, the geologic
materials penetrated during drilling, the static water level,
and the yield of the well as estimated by the driller. Calls
-------
to three local drilling firms produce similar records for the
wells serving the four houses between the development and the
landfill. A visit to the landfill site and discussions with
the operator disclose the age of the landfill, the methods of
landfilling used and the surface conditions and drainage char-
acteristics of the landfill.'
With these data available, the hydrogeologist is able to es-
tablish the following:
1. The houses in the development and the four houses north
of the development are resting on a layer of glacial till
between 10 and 30 feet thick.
2. Beneath this till layer is an extensive sand and gravel
aquifer which is probably about 50 to 100 feet thick.
Underlying this aquifer is crystalline bedrock.
3. The general direction of ground-water flow in the area
is from the mountainous area ten miles north of the city.
4. The gradient of the water table in the vicinity of the
development is low, but the permeability of the aquifer
is quite high. The rate of ground-water flow in the area
is about 2 feet per day.
5. The wells belonging to houses in the development, with
the exception of the eight contaminated wells, are screened
-------
near the top of the sand and gravel aquifer in an inter-
val of about 50 to 60 feet below land surface.
/_
6. With corrections for differences in elevation, the four
wells belonging to the houses north of the development
are screened at approximately the same depth in the aquifer
as the majority of the development houses.
7. The eight contaminated wells in the development are
screened substantially deeper than the other development
wells. In four of these, a 10-foot thick clay lens was
penetrated at the normal screening depth of 40 to 60 feet,
and the wells were drilled an additional 20 feet into the
sand and gravel beneath the clay. The remaining four
wells were drilled at a later date by a different drill-
ing firm and were inexplicably deeper.
8. The landfill, located 6,000 feet upgradient of the devel-
ment, is situated in an abandoned gravel pit, which is
probably connected directly to the aquifer serving the
development.
9. The landfill is roughly circular, covering an area of
about 45 acres, and is about 1,600 feet in diameter.
10. The contaminants reported in high concentrations in the
eight wells in the development are characteristic of
typical municipal landfill leachate.
-------
11. Mo significantly large source of contamination other
than the landfill and the sewer system is located in
>»
the immediate vicinity of the development or upgradient
of the development as far as the mountains 10 miles
north.
12. The landfill is 10 years old, has a broad, flat upper sur-
face, and the deposited refuse is covered daily with sand
taken from an unfilled portion of the old gravel bank.
13. Rainfall in the area averag.es 40 inches per year.
Based on these findings, the hydrogeologist concludes that it
is indeed possible, in fact probable, that the landfill is the
source of the contamination found in the eight wells. He rules
out the sewer as the source of contamination since it is the
deeper wells, rather than the shallow ones, which had become
contaminated.
Using the available geologic and hydrologic data, a cross
section of the area, including the landfill and the development,
is drawn illustrating how only the deeper wells would become
contaminated (see Figure "7 )• Since the landfill is probably
resting directly on top of the aquifer, leachate generated in
the landfill would flow into and move with the natural ground
water. From other landfill investigations, however, it is known
that leachate can flow as a distinct plume with relatively
-------
-------
little dispersement in the ground-water system. Furthermore,
this plume may tend to sink toward the bottom of the aquifer
as it noves. Thus, the plurre might be just thick enough to be
picked up by the deeper wells but still could flow underneath
the shallower ones, as illustrated in Figure 7 . The second
part of the problem, the 10-year delay for the contamination to
A
appear, is answered by the estimated flow rate of the ground
water. Assuming the leachate began to move into the aquifer
during the first year of landfilling, it took approximately
3,000 days to reach the vicinity of the first well. Because
the distance from the landfill to the well is 6,000 feet, ground-
water velocity would have to be 2 feet per day, which is what
it is estimated to be. An explanation for how contamination
traveled the 400 feet from the first well affected to the last
well affected in only 60 days (rather than 200) is provided by
the change in velocity of the ground water as it enters the cone
of influence created by the large number of pumping wells in
the development area.
The width of the affected area, one-quarter mile, is explained
by the width of the landfill itself (see Figure ff ). Since it
is possible for a leachate plume to migrate without substantial
dispersion and remain at approximately its original width for
substantial distances, and thus, should be at least 1,600 feet
wide (probably somewhat wider) as it reaches the development.
-------
I I
-------
Along with the data and findings, the ground-water consultants
include the following recommendations in their report to the
city.
1. Immediately advise the owners of the contaminated wells to
obtain their drinking water from other sources.
2. Collect water samples from all the unsampled wells in the
subdivision and analyze for chloride, calcium, and iron. If
any abnormal concentrations are found, advise the owners of
those wells not to drink the water.
3. Immediately institute an investigation to positively es-
tablish the landfill as the source of the problem, and define
the actual extent and rate of movement of the contaminants.
In addition, detailed water analyses should be performed to
determine what potential health hazards exist.
4. When the problem has been defined, establish what abatement
procedures might be effective. Evaluate the various possible
procedures and define which will be the most effective.
The City Department of Health decided to carry out the first two
recommendations themselves. The consulting firm is contracted to
undertake the work necessary to satisfy the third and fourth
recommendations.
-------
9.7.2.1 LANDFILL INVESTIGATIONS
The first phase of the consultant's investigation, to es-
tablish the landfill as the actual cause of the problem and
to define the nature and extent of the leachate plume is
undertaken as a series of tasks.
Task 1 - Assemble and analyze all available background data
(already done during preliminary investigations).
Task 2 - Conduct a field inspection of landfill site (already
done during preliminary investigation).
Task 3 - Conduct a resistivity survey to attempt to define
the depth and lateral extent of the leachate plume.
Task 4 - Drill a total of 6 wells down to bedrock to verify
the results of the resistivity survey and obtain
geologic and water samples. Conduct pumping tests
to determine actual hydrologic characteristics of
the aquifer.
Task 5 - Construct a water-balance model of the landfill to
IB««^__«»«^^^_ ^
accurately determine the contributions of precipita-
o~P
tion and underflow to the volume leachate generation.
r\
This task would be accomplished entirely with exist-
ing data.
-------
The results of the Phase 1 investigation indicate that the
preliminary analysis of the situation was essentially correct.
ff
Furthermore, the leachate plume is found to contain hazardous
constituents originating from industrial wastes which are
traditionally accepted at the landfill. The .volume of leachate
being generated by the landfill is calculated at approximately
80,000 gallons per day from precipitation with no significant
contribution from underflow.
Based on these results, two alternative abatement programs are
presented to the city. The first half of both programs is the
same, eliminate the source of the pollution. The second half
of the program deals with what to do about the leachate that
is already in the ground. Monitoring recommendations are in-
cluded with both programs.
9.7.2.2 ABATEMENT PROGRAM 1
It is recommended that placement of refuse of the existing county
landfill be stopped as soon as an alternate disposal site can
be located and prepared. The selection of a new site should be
based on geologic and hydrologic considerations so that a new
ground-water contamination problem is not created. Site prepa-
ration and landfilling methods should be based on the latest
technology to minimize the possibility of leachate contamina-
tion of ground or surface water.
-------
Preparation should begin at once to regrade the existing land-
fill to eliminate the flat top surface and provide adequately
steep side slopes to promote runoff of precipitation. The
upper surface of the landfill should be covered with a minimum
of two feet of compacted soil with a low permeability to mini-
mize infiltration. This upper layer should then be covered
with a one-foot layer of top soil and seeded. A dense vegeta-
tion cover should be maintained on the landfill surface to
maximize evapotranspiration.
It has been determined by aquifer tests that the leachate pres-
ently in the ground-water system can be removed by a series of
high-capacity pumping wells. Three 10-inch diameter wells would
be installed 400 feet apart across the plume (shown in Figure )
and 500 feet north of the development. The wells would be
drilled to rock and be screened from 80 feet below land surface
to rock, to include the entire thickness of the plume in the
screened zone. The wells would be pumped continuously at a
rate of 2,000 gpm (gallons per minute). This will establish a
hydraulic barrier which will block leachate flowing south from
the landfill site toward the development. In addition, leach-
ate south of the barrier wells will be drawn back toward the
wells by the induced reversal in gradient. When the polluted
water has been removed from the aquifer beneath the development,
the pumping rate of the barrier wells can be reduced to 700 gpm
-------
and the eight deep development: wells can be returned to use,
but with continual monitoring of their quality for a period
of tirr.e. •;
While this program will effectively eliminate the present prob-
lem, a new problem of what to do with the contaminated water
j,
pumped from the barrier wells will arise. Since the capacity
of the treatment plant is insufficient to handle this addition-
al volume, the water would have to be piped away and discharged
untreated either back at the landfill site or into the river at
the south end of the city. There are many serious problems with
these possibilities, however, and subject to further investiga-
tion, both may prove unacceptable. The only remaining alter-
native then would be the construction of additional treatment
facilities.
9.7.2.3 ABATEMENT PROGRAM 2
Discontinue landfilling and complete the existing landfill as
described in Program 1. Abandon use of the eight contaminated
wells for water supply but keep them intact for use as observa-
tion wells. Drill eight new wells to a depth of 50 feet below
land surface. These replacement wells would then be screened
above the contaminated zone, at approximately the same depth
as the other wells in the development.
-------
Allow the contaminated plume co flow along its natural course
toward the river. Since there are no city supply wells or
other private wells in its path, no additional effects will
be apparent until the plume reaches the river. The additional
three miles the plume must travel might be sufficient to attenu-
ate most of the contaminants. The progress of the plume should
be monitored by a series of observation wells placed along its
route. These monitoring wells will determine if attenuation
is actually occurring at a significant rate and if the plume
is altering its course. If at some time in the future it is
determined that the contaminants within the plume are not being
sufficiently attenuated and will be deleterious to the river,
a series of barrier wells should be installed to intercept the
plume prior to its reaching the river.
The city should consider the possibility of connecting the
northern development to the city water supply, while this does
not appear to be immediately necessary, continued close monitor-
ing of the location of the plume in the vicinity of the develop-
ment may detect an enlargement of the plume and all the wells
would have to be abandoned.
-------
A-l FUNDAMENTALS OF LEACHATE
In their publication, Summary Report; Gas and Leachate from Land Disposal
of Municipal Solid Waste. U.S.E.P.A., Cincinnati, Ohio, 1974, the U.S.E.P.A.
presents an excellent comprehensive summary on leachate, its production and
characteristics. Much of this material has been reproduced and included
in this appendix for the convenience of the user of the manual. Herein-
after, the above-referenced report will be called the leachate summary
report.
Two other reports on leachate which are pertinent to assessing potential
leachate contamination at land disposal sites are:
. Use of the water balance method for predicting leachate
generation from solid waste disposal sites, Office of
Solid Waste Management Program, U.S.E.P.A., October 1975,
(EPA/530/SW-168).
. An environmental assessment of potential gas and leachate
problems at land disposal sites. Office of Solid Waste
Management Programs, U.S.E.P.A., 1973, (SW-110).
These reports will also be referenced in this section and will be referred
to as the water balance report and environmental assessment report respectively,
It is intended that this appendix provide the user of this manual with suf-
ficient information to assist in performing an assessment of potential leachate
contamination at land disposal sites. This, in turn, is used to determine
the need, type and intensity of monitoring that should be assigned to a
A-l
-------
particular land disposal site.
LEACHATE PRODUCTION
In their environmental assessment report, EPA puts leachate production into
perspective. It states:
"It becomes quite evident that the main parameter affecting
leachate quality and quantity is purely and simply the
quantity of water flow through the solid wastes. Generally,
the more water that flows through the solid waste, the more
pollutants will be leached out. Therefore, the proper sani-
tary landfill design and operational approach is to eliminate
or minimize percolation through the solid waste. With the
smaller amounts of percolation, the pollutants tend to be more
concentrated, but the rate at which they are transmitted to
the surrounding environment is not so apt to exceed the capabil-
ity of the natural surroundings to accept and attenuate most
of them to some degree."
Therefore, one can see that the volume of leachate generation is influential
in both the extent of a leachate contamination problem and the relative
strength of the leachate and its concentration in the ground water being
monitored.
Estimating leachate generation can be useful in designing a monitoring
program, and interpreting the data collected in the following ways:
. Predicting the time of first appearance of leachate.
. Predicting the potential quantity of pollutants generated
at a land disposal site.
. Help explain fluctuations in monitoring well data that
••
may occur, and
. Relate operational characteristics and site conditions
to potential leachate generation.
A-2
-------
In the leachate summary report, and the water balance report, EPA
applies the water balance method as a useful tool in estimating leachate
generation at a land disposal site.
In addition, the leachate summary report provides an excellent summary
of leachate characteristics as has been observed by many researchers in
the field. Data are presented on the quality of pure leachate as well as
samples of leachate-enriched ground water. Examples are also given
depicting the relationship of leachate concentrations to quantity produced
and season of the year. A comprehensive list of references on leachate is
also presented.
For the convenience of the manual user, sections have been reproduced from
the leachate summary report and the water balance report and included as
part of this appendix.
A-3
-------
The following section has been reproduced from:
"SUMMARY REPORT: GAS AND LEACHATE FROM LAND
DISPOSAL OF MUNICIPAL SOLID WASTE", U.S. EPA,
Cincinnati, Ohio, 1974.
-------
SECTION VI
LEACHATE PRODUCTION
The various physical, chemical, and biological processes that occur
when solid wastes are disposed on land produce compounds that are sus-
ceptible to solution or suspension in water percolating through the
disposed solid waste. This percolating water containing solids de-
rived from the solid waste is called leachate. The volume of leachate
produced at any particular site is dependent on many factors, but
generally, is determined by the quantities of surface water infiltra-
tion and/or interceotion of groundwatsr. Compos iti on of Icachate is
highly dependent on the comoosition of solid waste, its aqe,-and the
environment in which it is located. Environmental conditions, such
as temperature, moisture regimen, and the availability of oxygen are
significant factors in determining the exact chemical constituents
contained within leachate.
VOLUME
,The sanitary landfill site is a part of the classical hydrclogic
cycle. The governing criteria for determining leachate volume are
those describing the phenomena occurring at the cover material sur-
face. A water balance can be written:
where WR = input water from precipitation
w"sR = input water from surrounding surface runoff
WGW = 1nPut water f™m groundwater
WIR = input water from irrigation
I = Infiltration
R = Surface Runoff
E = Evapotranspiration
-------
Infiltration can be defined:
I = ASs + 6Sp + L + WD [2]
where AS = change in moisture storage in soil
^ •
ASD = change in moisture storage in solid waste
K
L = leachate
WD = v/ater contributed by solid waste decomposition
Proper design and operation can eliminate input water from surrounding
surface runoff, groundwater and irrigation. Some control can be
exerted over infiltration, evaporation, surface runoff, and moisture
storage capacity of soils and solid waste. The volume of vater pro-
duced during solid waste decomposition is generally considered negli-
gible.
Use :of the v/ater balance has been proposed by Remspn, et al.
Fenn and Hanley,2 Salvato, et al.3 and California.1* The volume of
, leachate, tine of initial occurrence, and subsequent flow rate and
'allowable volume of irrigation v/ater can all be determined by appro-
priate use of the v/ater balance. The Rsuson work, supported in part
by U.S. EPA Research Grant R301947, provided a useful computerized
moisture routing technique. Salvato, et al., and the California sum-
mary discuss the various factors that influence rrnoff and infiltra-
tion and provide guidance for determining approximate values. Fenn
and Hanley applied the water balance to hypothetical landfills in
Cincinnati, Orlando, and Los Angeles.
Determination of runoff from landfill surfaces by the rational runoff
formula was proposed by Salvato, et al. They provided tables for a
rainfall of 25.4 mm/hour (1 inch/hour) intensity and 6-hour duration.
The empirical runoff coefficients (C) used v/ere from Frevert,
et al.5 and are provided in Table 5 along with calculated quantities
of runoff for a 25.4 mm (1-inch) rainfall. The influence of slope,
surface condition, and soil type on the quantity of runoff and the
potential for leachate production is clearly demonstrated in Table 5.
As great as 55 percent change in runoff and infiltration is attributed
to slope. As great as 173 percent change in runoff and infiltration
is attributed to soil type. As great as 71.5 percent change in run-
off and infiltration is attributed to surface condition (vegetation,
bulk density). A silt or clay loam, in a pasture land area at a
5 to 10 percent slope is generally recommended for encouraging run-
off, limiting erosion, and avoiding soil shrinkage oroblcns. As
such, a coefficient of 0.36 would apply and one mignt expect from a
storm of 25.4 ir.m/hr (1 inch/hr) intensity and 1 hour duration, approxi-
-------
mately 9.06 m3/ha (9,690 gal/acre) runoff and 16.3 n.3/ha (17,400 gal/
acre) potential infiltration. Of course a large amount of this in-
filtration is lost by evaporation and transpiration. The remainder
qoes first to meeting moisture retention (storage) capacity of the
soil and solid waste and then to leachate in accordance with
Equation 2. ;
»
Determination of the runoff from storms by the rational runoff formula !
is largely dependent on the accuracy of the coefficient, C, chosen j
for the specific site. Mot specifically considered in the rational
runoff formula are: the previous moisture conditions of the site and i
the limitation imposed by the hydraulic conductivity of the soil. ,
Infiltration rates generally cannot exceed the hydraulic conductivity
permeability) of the soil. The hydraulic conductivity of soils has !
been conveniently tabulated.* Table 6 provides estimates of maximum ;
hourly infiltration for these soils assur.-.ino Q = CiA is aoolicaDle,
the soils are saturated and uniform, and sufficient water is avail-
able. Comoarison of Tables 5 and 6 Indicates the necessity for care-
ful determination of the hydraulic conductivity of proposed cover
soils (differences as great as 1Q3 in the same soil group) and inter-
pretation of the results of the rational runoff formula.
Infiltration is dependent on the frequency, duration, and intensity
of rainfall. These precipitation characteristics are significant
in determining the previous moisture conditions of the soil and hence
the amount of water required to reach saturation when the hydraulic
conductivity of the soil will control infiltration rates. The Bureau
of Reclamation7 has related rainfall intensity to infiltration, and
has accounted for differences due to vegetation, soil type, precipi-
tation, end evaporation. Appropriate relationships are depicted in
Figure 2 and Table 7.
The importance of vegetation in promoting infiltration is clearly
shown in Table 5. The density and type of vegetation are also im-
portant in determining evaporation and transpiration. Consumptive
use of water. Table 8> is determiner; largely by the vegetative-soil
system, but ranges have been compiled.
Moisture retention by soil is dependent on soil type and previous
wetting. Soil will retain a characteristic amount of water against
the pressures exerted by gravity and plant roots. These are referred
to as field capacity and wilting point respectively. They are com-
monly expressed as a percent of volume or as a depth per unit depth
of soil. Examples are provided in Table 9. The difference in water
retained between the wilting point and the field capa.city is that
amount available for evapotranspiration and storage.
-------
Table 5. RUNOFF AND INFILTRATION FOR A 2.5 cm RAINFALL*
Surface condition
Pasture or meadow
(cover crop)
Flat
Rolling
Hilly
Cultivated
(no vegetatto)
not compacted
Plat
Rolling
Wily
BAftcr Salvatn. J. A.
Slope
S
7
10-30
0-5
9-10
10-30
. Vllklt.
Rational runoff coefficient6-0
Sandy
loam
0.05-0.10
0.10
0.10-0.15
0.16
0.15-0.80
0.22
*
0.30
0.40
t.62
N. 6. aid NN4
Clay or
silt
loam
0.13-0.17
0.30
0.18-0.22
0.36
0.25-0.35
0.42
0.80
0.60
0.72
Clay
0.40
0.65
0.60
0.60
0.70
0.82
. 1. E. "Unitary Landfill
Ruifoff In mVh«d>e
Sandy
loam
26.7
(2.730)
41.0
(4.360)
66.3
(5.900)
74.7
(8.160)
102
(10.900)
133
(14.100)
Leachatt
Clay or
silt
loan
77.1
(8,200)
91.1
(9,690)
107
(11.400)
128
(13.600)
153
(16,300)
184
(19,600)
Prevention and
Clay
102
(10.900)
141
(15.000)
155
(16.506)
59.1
(6.300)
too
(19.100)
210
(22.300)
Control."
Infiltration In mVhae
Sandy
' loan
< 230
, (24.500)
(22.900)
• 199
(21 .200)
180
! (19.100)
- 153
(16.300)
123
. (13.100)
t^^M»*l UDi^sT
•IMinM 1 Krlr i
Clay or
silt
loan
180
(19,100)
164
(17.400)
149
(15,800)
128
(13.600)
102
(10.900)
77.7
(7,630)
43 (10). 2084
Clay
153
(16.300)
115
(12,200)
1C2
(10.500)
102
(10.900)
76.7
(8,160)
46.1
(4.900)
(1971).
bFrevert. Schwab, {dsrfnster and Barnes. Soil and Water Conservation Engineering. Wiley, pp. 439 (1963).
cVcn TeChOM. "Handbook of Applied Hydrology.- (1964).'
dO • CIA.
•Nuobon In parenthesis refer to gallons/acne.
-------
RAINFALL, nun/hr.
100
£.
c
2:
o
M
H
M
Cn
55
Note: See Table 7 for application
of curve number. /
0.5 -
i
RAINFALL, in/hr.
Figure 2. INFILTRATION CALCULATION CURVES ADAPTED FROM "DESIGN OF SMALL DAMS
,,7
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Table 6. MAXIMUM HOURLY WATER TRANSMISSION UNDER SATURATION
Soil description
Hydraulic
conductivity
cm/sec
Hourly
transmitted
vol3umeb
m"/ha
Well-graded gravels or gravel-sand
mixtures, little of no fines
Poorly graded gravels or gravel-sand
mixtures, little or no fines
Silty gravels, gravel-sand-siIt
mixtures
Clayey gravels, gravel-sand-clay
mixtures
Well-graded sands or gravelly sands
little of no fines
Poorly graded sands or gravelly sands,
little or no fines
Silty sands, sand-silt mixtures
Clayey sands, sand-clay mixtures
Inorganic silts and very fine sands
rock flour, silty or clayey fine sands
or clayey silts with slight plasticity
>io
-2
ID'3 to 10~6
6 8
10- to 10-
10
10-
3 6
10- to 10"
6 e
10- to 10-
10'3 to 10"
>3.6xlO .
(>3.85xl05)
>3.6xl03 5
(>3.85x10 )
3.6x10 ,to
3.6x10- \
(3.85x10 to
3.85x10*)
l
3.6x10"3 to
3.6x10" i
(3.85x10, to
3.85x10- )
2
>3.6xlO n
(>.3.85x10 )
>3.6xl02 .
3.6x10 ,to
3.6x10-V
(3.85x10 to
3.85x10 )
3.6xlO~3 to
3.6x10- .
(3.85x10, to
3.85x10" )
3.6x10 ,to
3.6x10- ,,
(3.85x10 to
S.SSxlO1)
-------
-Table 6. HAXIKUM HOURLY l.'ATER TRANSMISSION UNDER SATURATION (Continued)
Soil description3
Hydraulic
conductivity
cm/sec
Hourly
transriHtrd
volun-.c"
m /ha
Organic silts and organic silt-
clays of low plasticity
Inorganic silts, micaceous or
diatomaceous fire sandy or silty
soils, elastic silts
Inorganic clays of high plasticity,
fat clays
Organic clays of medium to
.high plasticity, organic silts
Inorganic clays of low to medium plas-
ticity, gravelly clays, sandy clays,
silty clays, lean clays
10'* to 10-
-6
- to 10
10-6 to 10-B
•
ID"6 to 10-8
TO'6 to 10-8
3.6x10 .to
3.6x10,
(3.85x10* to
3.85X101)
3.6xlOto
3.6X10
'1
85x1 0
T
to
3.6x10-* to
3.6xlO-3.
(3.85x10 to
3.85x10- )
3.6xlO-J to
3.6xlO-3.
(3;85xTO: to
3.85x1 O-1)
3.6xlO'l to
3.6x10- ,
(3.85xicj to
3.85x10- )
aSoil description according to USCS.
lumbers in parenthesis are gal/acre.
-------
Table 7. REPRESENTATIVE VARIATION OF RAINFALL - INFILTRATION CURVES
WITH SOIL TYPE, COVER, AND PRECEDING MOISTURE CONDITIONS3
Soil type
'Sandy loam
Sandy loam
Clayey loam
Clayey loam
Cover
Turf
Bare
Turf
Bare
0.2
1
3
, 2 •
5
0.4
2
4
3
6
M va
0.6
Curve
4
6
5
8
lues"
0.8
numberc
6
8
7
10
1.0
8
10
9
12
aSanitary Landfill Studies: Aooendlx A — Sumrary of Selected Previous
Investigations. California Department of Water Resources. Sacramento.
1969. 115 p.
bM Increases with degree of soil saturation.
cCurve number refers to Figure 2.
= e
+ 1)
for noni-rr1gated areas.
M = e ( 60 + 1) ^ A f0r irrigated area such as parks, where A is
allowance for irrigation = 0.11.
where: e = evaporation = (0.9 - e6Q )
e annual
i
where: (e60) = pan evaporation for preceding 60 days.
(e annual) = man annual pan evaporation.
°60 s weighted preceding 60-day precipitation as:
d60 -
p(5-9) + p(10-14) + p(15-30) + p(31-60)
~ ~~ "6T67 *"
-------
Table 8. APPROXIMATE SEASONAL CONSUMPTION OF WATER3
Vegetation mm/unit area
Coniferous trees 102-229
Deciduous trees 177-254
Potatoes 177-280
Rye 457-up
Wheat 509-560
Grapes 152-up
Corn 509-191
Oats 711-1020
Meadow grass 560-1525
Lucern grass 660-1400
aAdapted from Urquhart, L. C., Civil Engir.ec-rir.o Handbook.
New York, McGraw-Hill, p. 9077January, U-50.
-------
Table 9. MOISTURE CRITERIA OF SOILS
son
Sand
Loam
Clay
Fine sand
Sandy loam
Silty loam
Clay loam
Clay loam
Field
%
7.5
25.8
43.3
12.0
20.0
30.0
37.5
45.0
capacity
in/ft
0.9
3.1
5.2
1.4
2.4
3.6
4.5
5.4
nun/m
75
258
433
120
200
300
375
450
Wilting
%
3.33
13.3
24.2
2.0
5,0
10.0
.12.5 '
15.0
point
in/ft
0.4
1.6
2.9
0.24
0.6
1.2
1.5
1.8
mm/m
33.3
133.0
242.0
20.0
50.0
100.0
125.0
150.0
Ref.
(1)
0)
0)
(2)
(2)
(2)
(2) .
(2)
Sanitary Landfill Studies, Appendix A - Suircnary of Selected Previous
Investigations.California Department of Water Resources, Sacramento,
1969.
Thornthwaite, C. W. and Mather, >J. R., "Instructions and Tables for
Computing Potential Evapotranspiration and the Water Balance".
Publications in Climatology, X(3), Drexel Institute of Technology,
Laboratory of Climatology. 1957.
-------
Table 10. MOISTURE RETENTION OF SOLID WASTE9
Initial Moisture
X Wet Weight
29.9
25.1
32.0
27.6
62
50
Added
moisture
m/m in/ft.
425
258
441
200
100
142
108-
125
208
125
5.1
3.1
5.3
2.4
1.2
1.7
1.3-
1.5
2.5
1.5
Solid Haste
Density ,
kg/mj lb/yd:
392 661 '
430 727
417 705
592 1QOO
337 570
314 530
Reference
1
1
1
1
2
2
.
3
4
5 "
Notes
c.d.e
c.d.e
c,d,e
c.d.e"
c,d,e
c.d.e
c.e
•
Notes: a adapted from A. A. Fungaroli and R. L. Steiner "Investigation of Sanitary Landfill
Behavior" Research Grant R800777 October 1973.
b unit wet density
c not corrected for evaporation and transpiration losses.
d includes H_0 retained in soil cover.
e includes H.O retained in sub-drain.-
References:
1. "Project Plan. Test Cell 2. Boons County neld Site." Solid anc! Hazardous Waste
Research Laboratory, U.S. EPA, Cincinnati Jan. 1973 (manuscript).
• . 2. Rovers, F. A. and Farquhar, G. J. "Infiltration and Landfill Behavior" in
Proceedings of the American Society of Civil Engineers. 99 (EE5), pp 671 - 690.
October 1973.
3. "Pollution of Water by Tipped Refuse" Ministry of Housing and Local Government,
Her Majesty's Stationery Office, London, 1961.
4. Merz, R. C., Final Report on the Investigation of Leaching of a Sanitary Landfill.
State Hater Pollution Control Board. Publication 10.' Sacramento, California
1954. 91 p.
5. Qasim, S. R. and J. C. Burchinal "Leaching from Simulated Landfills," Journal of
the Hater Pollution Control Federation 42, pp 371-379, March 1970.
-------
Moisture retention in solid waste is similar in concept to that of
soil except no data is available on the v/ilting point. It is gen-
erally assumed that water is lost fropi the solid waste in significant
amounts only through percolation. Table 10 and Figure 3 provide a
suirjnary of data on the field capacity of solid waste. Deeds-position
of the solid waste, particle size, density, and initial moisture
content account for the wide range in reported values.
The moisture retention capacity of solid waste has been proposed for
exploitation as a receptor of liquid wastes and sludges. Examples
are municipal water and wastewater treatment plant sludges, commer-
cial wastes such as vegetable market e.nd restaurant wastes, and in-
dustrial liquid and sludge wastes not permitted to be discharged to
streams. Such a contribution of water to the solid waste in the
sanitary landfill does not necessarily create a leachate problem or
significantly affect the total volume of leachate produced. The fol-
lowing hypothetical example will indicate the quantities involved.
A typical sanitary landfill, 592 kg/m3 (1,000^/cu yd) of municipal
solid v/aste, placed 3 meters deep (9 feet) will hold approximately
760 ram (30 inches) of H20/unit surface area (18.7 gallons of hhO/sq ft)
before steady state leaching occurs. If no sludge or high r.oisture
bearing solid v/aste is added to this waste, then 3 years will likely .
elapse before steady state leaching is established (based on assump-
tion of 25* rr.ri (10 inches/sq ft) annual net infiltration). If 508 rai
(20 inches) of excess moisture (12.4 gal/ft2) is added to the solid
waste during deposition, then steady state leaching will likely occur
1 year later. Total leachate volurr.e produced in the first 10 years
with no intentional moisture addition during deposition is aoproxi-
mately 2,540 mm (100 inches), (62.2 callons/sq ft); if 503 .V.TI (20
Inches) of moisture is added during deposition, then leachete volurr.e
after 10 years is approximately 3,050 ran (120 inches), (74.5
gallons/sq ft).
It is obvious from the example that'the occurrence of leachate will
be accelerated if water is added to the landfill. It is not as ob-
vious, nor is it as easy to evaluate the impact on leachate and gas
characteristics. Additions of water and the compounds dissolved in
it may accelerate decomposition as well as inhibit it; it may create,
magnify, or reduce the impact of leechate on the environment; opera-
tional problems may be solved as well as created.
The seasonal dependence of evaporation, transpiration, and infiltra-
tion and the dependence of all these factors on the distribution of
rainfall and available moisture throughout the year create a complex
problem that has not been rigorously solved. Remson presented a
moisture routing procedure easily adaptable to electronic ccmputa-
-------
10
a. Adapted from A. A. Fungaroll and R. L. Stelner,
"Investigation of Sanitary Landfill Behavior"
Research Grant R800777, October 1973.
b. Moisture retention based on data from Initially
saturated samples.
\ ••
VI
01
3 6
o
3.
«D
u
I
«J
s
«J
z
£
3
*->
\st
5
a
O
O
0
,Q O
? o
o
Go
ee w°e °°
or3 IP Q
5
Q>
fpLlD
O
A
D
(33
O
Size
A
3
C
D
E
5O
tn-.n\>
0.89
3.20
4.CO
13.00
S2.00
L'nground ?
ISO
200
300
400
500
600 700 COO 900
Unit Dry Dens'lty (pounds/cu yd)
Figure 3. Moisture retention capacity of solid waste1' *
-------
tion. Fungaroli8 developed a national evaluation of potential infil-
tration, Figure 4, based on annual averages for evapotranspiration
and rainfall and no surface runoff. Inclusion of surface runoff re-
quires Identification of site-specific characteristics; evaluation
of leachate volume is best left to analysis of specific sites, rather.
than regional generalizations. Fenn and Hanley applied the water
balance, including provision for surface runoff and evapotranspiration
for Cincinnati, Orlando, and Los Angeles.
Control measures, such as diversion of upland drainage, sloping of
cover material, use of relatively impermeable soils for cover mate-
rial, rapid attainment of final elevations, planting cf high transpir-
ing vegetation, use of impermeable membranes overlying the final lift
of solid waste, maintenance of final grades, and use of subsurface
drains and ditches to control groundwater, are available to the de-
sign engineer and operator. Use of impermeable membranes requires
vents to nonage landfill cases and drains tc manege tha intercepted
infiltrating water. There is a general paucity cf quantitative in-
formation on the use of these controls.
Hughes, et al.9 calculated from piezometer calculations that 40 to 50
percent of the annual precipitation of Illinois of 838 ram (33 inches)
'will infiltrate the surface of landfills to produce leachates. In
the dry California climate ir.ore than two-thirds of the simulated
rainfall applied to a solid waste cell was evaporated.10 The only
landfills where the amount of runoff is actually measured are the
test fills in Sonoma County, California.11
The results of the test cells in Figure 5 show that with a low amount
of rainfall approximately 40 percent leaves the landfill as overland
runoff. At higher intensities, a constant amount of suprox.inately
14 mm (0.55 inch) is retained at the surface of the fill while pre-
cipitation in excess of this aRicunt appears as runoff water.
Schoenberger and Fungaroli12 found that during the winter period two
landfills in Pennsylvania produced leachate at a rate of 0.29 cm/day
and 0.23 cm/day which amount is equal to the net precipitation (rain-
fall-evaporation) in that period. Lower percentage infiltration are
experienced in Europe. Only one European study measured a leachate
volume equal to 44 percent of the yearly precipitation.13 More
typical values lie around 10 to 26 percent (Reuss, 1971) or 10 per-
cent11* (Pierau, 1968) corresponding with an amount of leachate of
0.03 to 0.10 1/sec/ha or 0.3 to 0.9 mm/day. Klotter and Hantge15
(1969) measured a flo;/ rate of O.C6 1/sec/ha for a 9 ha. landfill,
while Knock and Stegnan16 (1971) calculated a volume of 0.08 1/sec/ha.
The considerable spread in the relative amount of leechate generated
from landfills may indicate that by properly manipulating the nature
and the slope of the surface cover, the amount of Teachate can be re-
duced or enlarged as desired.
-------
// //• '• ' *F~«.Vv»v- £&~*f -:N
(/£ ^A;v::^v>.v- -:•
1/rB'A^ ^--^ :
^tV ^X^!^V):v^
I,;-' •';. . <^ Jk v ;.,'\ .5-.>..
-------
I-'
l«4
C_
(J
tJ
3.0
2.0
Relation between amount of dolly precipitation
and runoff from the pilot field scale sanitary
landfills cell A and C and cell Q, Sonona County
during the winter of 1972 and spring of 1973.
The cells have a 2 feet thick clay cover placed
under a 2 X slope.
first rain
of the season
observed quantity
of runoff
0.5
270
RUNOFF, (in.
Figure5 . OBSERVED RUNOFF FOR PRECIPITATION EVENTS.
00
-------
The critical area of limited information appears to be determination
of surface runoff/infiltration under surface conditions prevalent at
sanitary landfill sites. Such factors as slope, erosion, vegetation,
soil density, and soil type are factors that need to be studied fur-
ther, l.'ork presently being conducted under U.S. EPA Research Grant
R802412 is evaluating the net infiltration through simulated sanitary
landfill cover materials with three soil types, three soil densities,
and three types of vegetation. This work needs to be expanded and the
influence of slope determined. Hydraulic properties of cover mate-
rial and solid waste need to be determined. An extensive review of
existing water accounting and routing methods, culminating in a
method for leachate volume prediction and its verification is needed.
CHARACTERISTICS
The compositions of leachates reported 1n the literature are quite
diverse. R?ngps of specific chenical characteristics of those studies
listed in Table 11 are typical. 'The breadth of reported data are also
typical for individual studies17 over a long period of time. The many
factors that contribute to the spread of data are tir.a since deposi-
tion of the solid waste; the moisture regiman, such as total volune,
distribution, intensity, and duration; solid waste characteristics;
temperature; and sapling and analytical methods. Other factors
such as landfill geometry end interaction of leachate with its envi-
ronment prior to sar.-.ple collection also contribute to the spread of
data. Nost of these factors arc rarely defined in the literature,
making interpretation and coir.parison with other studies difficult,
if not rather arbitrary.
Some cements regarding the studies tabulated-are warranted." Cursory
examination of Table 11 indicates leachate is generally high in or-
ganic content (BOD5 =10,000, COD =15;COO, TOC =5,700) and total solids
(>1 percent), is slightly acid (pH 5.0*1.0) and contains low heavy
metals (<1.0 ppm) except for iron which is commonly present in levels
of 1,000 ppm.
The data presented from the Solid and Hazardous Waste Research Labo-
ratory were obtained at the Boone County Field Site Test Cell 1 which
contains 395 tons of municipal solid waste compared to 592 kg/m3
(1,000 lb/yd3. Test Cell 1 was constructed in 1971 in accordance
with best available sanitary landfill technology at that time.
The data reported from the University of Illinois were obtained under
U.S. EPA Research Contract 63-02-0162. The leachate vas generated
from a laboratory lysirr.eter, 1.22 m diameter (4 feet), containing
1,520 kg (3,353 pounds) of shredded solid waste, 33 mm (1.5 inch)
grate opening, compacted to 330 kg/m3 (556.9 lb/yd3). Water was
-------
The critical area of limited information appears to be determination
If surface runoTf/Infiltration under surface conditions Prevalent at
sanitary landfill sites. Such factors as slope, erosion, vegetation,
soi dens ty and soil type are factors that need to be studied fur-
ther T/ork presently being conducted under U.S. EPA Research Grant
TO02412 is cwlwtlng the net infiltration through simulated sanitary
landf 11 cover Materials with three soil types, three soil densities,
and three types of vegetation. This work needs to be expanded and the
Influence of slope determined. Hydraulic properties of cover ma«-
rla and solid waste need to be detennined. An extensive review of
existing water accounting and routing methods, culninating in a
method for leachate volume prediction and its verification is needed.
CHARACTERISTICS
The compositions of leachates reported in the 1 terature are *"*
diverse'. Ranaes of specific chemical characteristics of tho>e studies
listed n Table 11 are typical. The breadth of reported aata are also
typical ?or individual studies^' over a long period of time The many
factors that contribute to the spread of data are time since deposi-
. tion of the solid waste; the moisture regirr.en, such as total yo ume,
distribution, intensity, and duration; solid waste characteristics,
temperature; and sampling and analytical methods. Other £^°r* .
such as landfill geometry and interaction of leachate witn i^s envi-
ronment pr?or to ILple collection also contribute to tta spreaci of
data. Most of these factors are rarely denned in the literu-urc.
making interpretation and comparison with other studies difficult,
if not rather arbitrary.
Some consents regarding the studies tabulated are warranted Cursory
gS^en^
?>1 Sercertl Is slight y acid (pH 5'.0±1.0) and contains lea heavy
ieta?s < eilept for iron which is co-only present in levels
of 1,000 ppm.
The data presented from the Solid and Hazards Waste Research Labo-
ratory were obtained at the Boone County Field Site Test Cell ' v'nicn
contains 3S5 tons of municipal solid waste compacted to 592 kg/m-
(1,000 Ib/yd*).17 jest Cell 1 was constructed in 1971 in accordance
with best available sanitary landfill technology at that tin:e.
The data reported from the University of Illinois were obtained under
U.S. EPA Research Contract 63-02-0162. The leachate was generated
from a laboratory lysimeter, 1.22 m diameter (4 feet), containina
1,520 ka (3,358 pounds) of shredded solid was us, 33 irai (1.5 inch)
grate opening, compacted to 330 kg/m3 (556.9 Ib/yd'). Water was
-------
TABLE 11
UACHATE COMPOSITION
CONSTITUENT
COD
•V-'
nil
F '
TS
TLi
1SS
£S:TY
!-.• - -VIsS
U'aCO,)
TO: XL-S-
UV. 'J-P
•.s1 -s
1 n"**' t* — M
" i :"
Ca
Cl
Vn
1^
Sf.FAU
Fc
Zn
Cu
CJ
Pa
SHW™
16. ooo-::. ooo
7,500-10.000
5 '-6 i
.C'.CPO-1-i.OOP
lU.COO-li.CUC
ld'-700
6 .000- 9 .COO
300-4,000
3.5PP-5.000
25-35
13-33
2i7.7
0.2-0.8
900-1.700
tec-coo
45C-500
Ai.0-650
•5-1J5
160-J50
21C-325
10-30
0.5
0.'.
1.6
>.oTVt All flrurus in M»
U OF ILtJ2>
45.0CO-71.0CO
14,000-28,000
4.5-6.0
34,000
15.600-23,000
139
9.400-16.800
20-100
6.5
400-1.000
0.5-10.0*
2,300-4,000
1,500-2.500
750-1,600
Kl<0-2 , JOO
900-1,550
530-1.100
730-2.200
104
0.5
1.25
DREXlP
1,000-51,000
3.7-8.5
0-4.1,000
10-26,300
0-9,700
0-5.500
0-130
.0-482
4.7-2,340
0-7,703
25-450
0-1716
0-167
0-9.9
^
,320-12,000
,500-11.000
,230-5,000
5.2-5.6
,442-12.500
34-610
558-2.280
4SO-1,'J40
2.8-26
56-187
125-750
98-335
64-143
81-156
3-10
26-75
9-95
74
0.48
17
A i
1.16
A. TECH
RECIRCULATE
.2CO-9.28S
,750-6,900
256-2,798
4.3-5.4
.627-6,918
12-385
302-1,370
370-1.040
0.63-22
68-114
60-433
91-248
62-109
12-138
4-65
17-f.3
4-110
<0.05
<0.03
<0.03
OLIS AVC..
LAHDFILC '
, 700-10. 6S(
,350-8,450
3.9-8.1
.023-7,790
1800
1400
12
80
400
20
330
5.5
UPAGEC'
161
360
125*
,104
1630
690*
0.3
0.14*
136
203
63
85
1
0.24
110
106
0.10
<0.5
DDL
1.0
DOTAGE
KM63
2,940
4,560*
3,910
4,720
2250*
0.17
0.5*
447
946
613
220
1
0.09
723
12
0.05
-------
TABLE IT (Continued)
COSSTIPJEST
COD
EOD.
7CC5
pi!
TS
r>s
TSS
srccinc
CO-ai'CMSCE
AF.KAUSITY
^°3
T07\[__p
C.U.-0-P
Nil, -il
vi'«;o -N
Ca
Cl
>'.'a
K
so.
".I
I'.g
r»
zfi
Cu
Cd
MISSION CANYON LANDFILL
J-16-t.e
76,600
10,900
5.75
44,900
172
9860
22,800
0.24
0
7200
660
767
G8
1190
15,600
2820
*-"-"•
3042
908
7.4
13,409
220
8677
8930
0.65
270
216
2355 '
1160
440
19
8714
4.75
SONOMA, CALIF. (9)
UMlfcOL
26,750-33,500
15,900-24,600
4.3-5.4
15,190-16,890
128-323
0-5480
-0.38-9.8
.33-304
3.2-4.3
1041-1700
1200-1300
820
445
725-1070
28
2.15
<2.0
OTf
89,520
20.400
4.6
21,010
238
3050
79.2
194
4 7
1560
1210
930
910
560
95
0.4
2.0
W.VA. U.(10)
CYLINDER C
33,360
5.88
59,200
20,850
10,950
128
1.106
2,790
2.310
1,439
3,770
768
420 .
8GO
•
MADISON, WISC.
HILLED UNCOVERED
71,680
27,700
5.97
55,348
202
16,600
'
t *
98
29
1028
10.29
3900
2467
1500
2300
1558
1140
1040
370
0.75
0.375
1.C5
MADISON, WISC. (11)
UHMILLED COVERED
16,580
5,906
5.72
7930 •
192
2610
• .
65
85
347.4
4.29
572
474
330
900
77
220
91
13
0.65
0.05
0.80
RANGE OF
ALL VALVES
40- 89,520
81- 33,360
256- 28,000
3.7- 8.5
0- 59,200
584-44,900
10- 700
2810- 16,800
0- 20,850
0-22,800
0- 130
6.5- 85
0-1,106
0.2-10.29
50-7200
4.7-2467
0-77CO
28-3770
1-1558
0.09- 125
17-15,600
0-2020
0- 370
0- 9.9
<0.03-17
<0. 10-2.0
-------
applied doily to bring the solid waste to field capacity within 30
days, and thereafter en equivalent of 0.89 mm/week' (0.035 in) was
added to generate sufficient leachate for evaluation of leachate
treatment methods.
Leachate data reported by Drexel v/cre obtained under U.S. EPA
Research Grant RC00777. The solid v/aste used was not processed; the
laboratory column was 1.83 m (6 feet) square, and initially was packed
2.44 m (8 feet) deep.29
Data presented from Georgia Institute of Technology are from ongoing
U.S. EPA Research Grant, RS01397, to investigate the feasibility of
recirculatir.g leachate back through the landfill as a treatment
method. Again, the simulated landfill conditions were utilized for
study purposes. The refuse was compacted into a 3.05 m x .915 m
(10 ft x 3 ft) column in two 1.52 ni (5 ft) lifts to a dry density
of about 318 kg/m3 (535 lb/yd3). To expedite the production of
leachate, 948 1 (250 gal) of tap water v/ere added after placement of
the soil cover. A more detailed description of the project and the
results to date are provided by Pohland and Mao.18
The 01 in Avenue data are from the work done at the University of
Wisconsin to determine the treatability of leachate using a variety
of classical treatment methods. From this work the concept of anae-
robic digestion followed by aerobic polishing v.«s formulated snd led
directly to the pilot plant studies that are still ongoing at a land-
fill in the Milwaukee area. The original laboratory scale studies
ere available in a progress report for the period June 1, 1970 to
August 31, 1971, entitled "The Treatability of Leachate from Sani-
tary Landfills,"19 authored by R. K. Ham under U.S. EFA Research Grant
R801814.
The DuPage and Winnetka data were taken from Hvc'rocsolosy of Solid
Waste Disposal Sites iji Northeastern .Illinois.*u SpedffcaTly,
groundwater quality in the near vicinity of sanitary landfills is
represented.
Research was conducted by Merz21 at Riverside, California, in a test
bin. This represents the earliest extensive leachate study. The
basic constituents identified appear to agree with the most recent
analysis of leachate.
The data presented for the Mission Canyon landfill22 gives a good indi
cation of the age factor when analyzing leachate. As can be seen
the early leachate analyses reported high COD and EOD5 values very
typical of fresh leachatcs. Some 3 years later the effects of age and
materials are noted in the low COD—all readily oxidizable organics
I
I
|r
-------
already removed--and the BOD5 is also low indicating material re-
miring if^fconducive to Siolocjical degradation or tnat not much
naterial is even there. The significant increase in chlorides,
sodium! and ^Sssliun over a 3-year period compared to decreases in
all other parameters is interesting but unexplained.
The Sonoma data23 are from an ongoing Demonstration Grant l-GOG-EC-00351
Conclusions have not as yet been made; the data are presented to in-
dicate the effect of high moisture throughput on leachate charac-
teristics.
Another study using shredded solid waste, but 1n combination with
unshredded solid waste, was conducted by Qasim and Burchinal .2"
Chian, et al.25 reported on the characteristics of two >achate sam-
nles provided by R. K. Ham at the University of Wisconsin. The in-
SSseTsilld waste surface area and lack of cover "tcrial has a
drastic effect on increasing the quantities of materials leacned.
A detailed characterization study by Chian and DeHalle" showed that
the majority, 78 percent, of the organic matter in J«*h leacha^e,
Figure 6. consisted of low molecular weight compounds, /B percent
of which was free volatile fatty acids; also, significant Counts
of the heavy metals wore chelated by the humic carbohydrate-like
Urge modules and the fulvic acid snail molecules Leac ate from
an old landfill, Figure 7, was found to consist almost entire y of
small molecules of fulvic acid and hsalc-llke materials capable or
chelating heavy metals; no free volatile fatty acids were detected.
Heavy metal concentrations listed in Table 11 are generally less than
1 Sg/1. Table 12 indicates the solubility of several heavy metal
salts in water. The extent to which a substance will dissolve in
another varic-s greatly with different substances and dcpcnos on tne
nature of the solute (in this case the heavy metals) ana solvent, the
Kature. and the pressure. In general, theeffgt of pressure
on solubility is small unless gases arc involved. However, the effect
of temperature is usually very pronounced, as can be seen from tne
table of solubilities for various temperatures.
In general, compounds of similar chemical character are more readily
soluble in each other than are those whose chemical character is en-
tirely different. As presented'in the table, inorganic ma..erials are
dissolved in water, some to a large extent because of chcaical simi-
larities, some hardly at all due to vast chemical differences.
The substances presented in the table were selected as representative
of those that have the highest interest at this tirr.e. The tabulated
data arc for water at or near pH 7.0. When applying these figures
32-
-------
32Cp 48 r 80Cp
28C
.240
o
n
o
I 200
o
«.->
r 42- 700
- .600
o
o
ISO
I2C
o
jQ
Ǥ 80
40
0
o
'ci
-o 18
o
"6
-" 12
- 6
l- 0
TOC
— /-Carbonyl
-500
o
- 30C
- 200
- IOC
f J\ r-Phenolic OH
r\ / w
\/T
/Kh
I \l\ \ \
/-Carbohydrate / // / \v\ \ \
>- 0
SO -i
7(
30 o-
320
SOU-
"n
-tU n
(f /-Corboxyl fc^V
t;
c>
240^-
200-2
o
!GO
120
80
40
0
o
O
Elution Volume, ml
Figure 6. ELUATE OF THE 500 mw ULTRAFILTRATION RETENTATE- OF A YOUNG LEACHATE ON A G-75 SEPUADEX COLUMN. .
-------
18 -i 18
10
JY « \_ ».-
>o—o-T^-*0/v i^Corboxyl ' o-V"
0 \ / \ i *!~~"
icnolicOH^- .' \! s ..L.
1 t~»m^ ^ ^^^^^•^^•^^•••'•'••^•^ ^~^
Figure 7.
EL ATE OF THE 300 » ULTRAFILTKATION KETENTATE OF AN OLD LEACHATE ON A fi-75 SEPHADEX COLUMN.
-------
Table 12. SOLUBILITIES OF SELECTED HEAVY METAL COMPOUNDS3-b
TEMPERATURE
Substance
CdCl2
CdSO,,
CuCl2.SH20
CuSOi..5H20
Fed 3
FeS0^.7H20
PbCl2
PbSOi,
HgC1.6H20
MgS0^.7H20
HgCl2
ZnCl2
ZnSOJ7H20
0 C
90.0
76.48
70.7
14.3
74.4
15.65
0.6728
6.0028
52.8
—
3.6C
—
41.9
20 C
134.5
76.60
77.0
20.7
91.8
26.5
0.99
0.0041
54.5
35.5
--
432.0c'd
54.4
i
40 C
135.3
78.54
83.8
28.5
—
40.2
1.45
0.0056
57.5
45.6
-
•
M
100 C
147.0
60.77
107.9
75.4
535.7
~
3.34
'
• 73.0
—
61.3°
615.0C
"
aThis table shows the amount of substance (anhydrous) which is soluble
in lOOg of water at the temperature 1n degrees centigrade.
Adapted from Perry's Chemical Engineers* Handbook, Fourth Edition,
McGraw-Hill, flew York. 1950.
cParts by weight of substance soluble in 100 parts by weight in water.
Measured at 25 C.
-------
to leachate some variances should and will be expected. In leachate
the pH is usually toward the acidic side of the scale, pfl 5.0 to 5.5,
and thereby significantly affecting microbial and chemical reactions
acting on the heavy metals. Ionic and r.onionic materials also in-
fluence the overall solubility scheme of a particular metal. Addi-
tionally, the dissolved solids along with the potential buffering .
effect of the carbonate-carbonic acid and the volatile acid systems
further increase the likelihood for deviation from the pure water
system. Thus, it can be stated that the table gives an indication
of the solubility of certain metal compounds in water at different
temperatures and some inferences can be made from them regarding
heavy metal concentrations in leachate.
Extensive bacteriologic content of "leachate 1s not available. Fecal
colifonn and fecal streptococci data from the Boone County Field Site
are presented in Figures 8 and 9. Unpublished data26 obtained from
the Illinois laboratory study25 indicate a similar trend of high
numbers of initial vecal coliform and fecal streptococci, follcv.-cd
by a gradual, but definitive oec-iine to very lev; numbers cf bacteria.
Peterson27 has reported isolation of poliovirus from a laboratory
landfill. Thus the public health importance of leachate discharge
. to a stream is further supported, since an operational landfill will
continually receive new pathogen-containing solid waste.
The relative environmental significance of leachate Is difficult to
determine on a national basis cue to the specificity of site condi-
tions that control the moisture regircen and hence, leschate and gas
production. The following hypothetical example is offered cr.ly for
illustration; it represents a typical case east of the l-'iississippi
River {Figure 4). It does not represent a worst case condition,
Pierau1" measured leachate production at 0.9 imi/day (12 in/year). A
rule of thuirb for annu?l utilization of landfill soace is l.SSrn/ha/
10,000 population (15 acre feet per ,10,000 population). Landfill
depth of 4.56 m (15 ft) is not unusual. Leachate volu.re then is
123 1/cap/yr (32.6 gal/cap/yr). If one assumes a solid waste gen-
eration rate of 970 kg/cap/yr (2,000 Ib/cap/yr), then from Rovers and
Farquhar,23 the annual per capita extraction of materials from solid
waste initially at 30 percent moisture by wet weight would be 2.58 -
7.8 kg (5.7 to 17.2 Ib) COO, 16.1 - 33 kg (35.6 to 72.8 Ib) 80DS.
0.137 - 2.6 kg (0.3 to 5.7 Ib) chloride, 0.0318 - 1.0 kg (.07 to
2.2 Ib) ammonia nitrogen, 0.0310 - 0.59 (.07 to 1.3 Ib) organic
nitrogen, and 0.136 - 1.31 kg (0.3 to 2.9 Ib) sulfate. The duration
of this rate of extraction is not known but would eventually de-
crease.
The above ranges of leached material quantities were determined ex-
perimentally over finite tine periods. Fungjroli and Steiner29
have indicated a relatively constant leaching phenomenon; the quantity
-------
10'
10
0 10'
§
10
1 ,
~ 10
1/1
23
•• 10
10J
FALL
WINTER SPRING SUHMER FALL WINTER SPRING
0 10 20 30 40 50 60 . 70 80 90
VTDCS FROM 9/1/71
Figure 9. FECAL STREPTOCOCCI IN LEACHATE FROM THE UPPER PIPE OF THE BOONE COUNTY FIELD SITE, TEST CELL 1.
-------
c 10<
H
o
§ 1
a •
T:
I
£ 10*
I
g 10'
• 10'
10°
FALL W1STER S?RIXC
FALL
10 20 _ 30 . .40 50 60 .- 70
WEEKS FROM 9/1/71
80
90
FIGURE 8. FECAL COLIFORM ISOLATED.FROM THE UPPER PIPE OF Tlffi BOO!^ COUNTY FIELD SITE, TEST CELL I
-------
vt
5
Bfi
U
20
IS
1C
U
12
10
8
6
CHL02IDE
Cw&IATXVB CKAXS/FT.2 KZXOVEO
VS. QUANTITY OF LEAOlATE/FT.2
i i i .1
I '
*. After Fungaroli £ Scelner
ion of Sanitary
Schavior" Ftr.il
Report nubsictcd to Solid
and Hazardous Waste F.cucarch
Labora;oj:y for Research Grant
'R800777 Oct. 1973.
b. Field capacity reached at
30 liters per ft.2 test.)
10
100
1000
LITERS/FT.2
CUMULATIVE CHLORIDE LEACHED4•
Figure 10.
-------
of materials leached per unit surface area is related to the leaching
volume per unit surface area. Typical results are shown in Figures
10, 11, and 12. The duration of this study indicates sanitary land-
fills have a long-term effect on the environment.
-------
100
93
80
70
60
50
40
30
20
10
y \i**vvcc
'CCIUUTIVE CXAMS/FT.2 REMOVED
VS. QUANTITY OF LEACHATE/FTv2
t t I i I l I
] 11
lilt
10
LiTERS/rr.2
100
10CO
COJUUTIVE HARDNESS LEACHED0
Figure 11.
-------
After Funs/iroli 4 Srelncr
"InvcsclRstioa of Sanitary
I.ar.«i:ill Echavior" XIr.nl
Report suVT.ittc
-------
References
1 Rcmson, I., A. A. Fungaroli, and A. W. Lawrence. Water tloven-.ent
in an Unsaturated Sanitary Landfill. Proceedings of the Am. Soc.
of Civil Engrs. 94(SA2):307-316, April 1963.
2. Fenn, D. G., and K, J. Hanley. Use of the Water Calance I'ethod
for Predicting Leachate from Sanitary Landfills. Unpublished
manuscript. Office of Solid Waste Management Programs, U.S. EPA.
June 1973. 59 p.
3. Salvato, J. A., W. G. Wilkie, and B. E. Mead. Sanitary Landfill
Leachate Prevention and Control.- Journal WPCF. 43_:2084-Z100,
October 1971. -
4. Sanitary Landfill Studies: Appendix A—Sundry of Selected Pre-
vious Investigations. California Department of Water Resources,
Sacramc-nto. 1S59. 115 p.
5. Frevert, Schwab, Edminster, and Barnes. Soil and Water Conserva-
tion Engineering. Wiley. 1963. 439 p.
6. Brunner, D. R., and D. J. Keller. Sanitary Landfill Design' and
Operation. U.S. EPA, Washington, D.C. Publication SW-6bts.
1972. p. 17.
7. Design of Small Dams. 1st ed. Washington, U.S. Govt. Print.
Off., 1960. 611 p.
8. Fungaroli, A. A. Pollution of Subsurface Water by Sanitary Land-
fills: Vol. 1. U.S. EPA, Washington, D.C. Publication S!.'-12rg.
1971. 131 p.
9. Hughes, G. M. Hydrogeology of Solid Waste Disposal Sites in
Northeastern Illinois. Office of Solid Waste Management Programs,
U.S. EPA, Report SW-12d, Washington, D.C. 1971.
10. Kerz, R. C. Final Report on the Investigation of Leaching of a
Sanitary Landfill. Publication Number 10, State Water Pollution
Control Board, Sacramento, California. 1954.
11. Sonoma County Refuse Stabilization Study; Second Annual Report.
Department of Public Works, Santa Rosa. 1973.
12. Schoenberger, R. J., and A. A. Fungaroli. Treatment and Disposal
of Sanitary Landfill Leachate. _In_ Proceedings: Fifth Kid-
Atlantic Industrial Waste Conference, Drexel University,
Philadelphia. 1971.
-------
13. Pierau, H., and G. Muller. The Significance of the Hygienic Un-
objectionable Disposal of Activated Sludge Together with Domes-
tic Refuse. Stadthygiene [German] 21^ 82. 1970.
14. Pierau, H. Results of the Investigations of Test Fills and Exist-
ing Disposal Sites. The Stuttgarter Journal of Civil Engineering
[German] £L_ 27. 1968.
15. Klotter, H. E., and E. Hantge. Disposal of Refuse and the Pro-
tection of Grcundwater, Refuse and Waste [German] 1 ^ 1. 1969.
16. Knoch, J., and R. Stegman. Experiments of the Treatment of Land- ,'•
fill Leachate/ Refuse and Waste [German] 6^ 166. 1969. ...
------ . ! i
17. Leachate Generation and Composition: Test Cell 1, Boone County •'
Field Site. Solid and Hazardous Waste Research Laboratory, U.S. '
EPA, Cincinnati". May 1973. 20 p. (manuscript)
18. Pohland, F. G., and M. C. Mao. Continuing Investigations on
• Landfill Stabilization with Leachate Recirculation, Neutraliza-
tion, and Sludga Seeding. Progress report to Solid and Haz-
ardous Waste Rssearch Laboratory for Research Grant R801397.
September 1973. 79 p.
19. Boyle, W. C., and R. K. Ham. Treatability of Leachate from Sani-
tary Landfills. Paper presented at 27th Annual Purdue Industrial
Waste Conference. 1972.
20. Hughes, G. M. Hydrogeolcgy of Solid Waste Disposal Sites 1n
Northeastern Illinois. Office of Solid Waste Management Pro-
grams, U.S. EPA, Report SVM2d, Washington, D.C. 1971..
21. Merz, R.C. Final Report on the Investigation of Leaching of a
Sanitary Landfill. Publication Number 10, State Water Pollution
Control Board, Sacramento, California. 1954.
22. Meichtry, T. M. Leachate Control Systems. Los AngeTes Regional
Forum on Solid Waste Management. May 1971.
23. Sonoma County Refuse Stabilization Study; Second Annual Report.
Department of Public Works, Santa Rosa. 1973.
24. Qasim, S. R., and J. C. Burchinal. Leaching from Simulated
Landfills. Jour. Water Poll. Control Fed. 42, pp. 371-379.
March 1970.
-------
The following section has been reproduced from:
"USE OF THE WATER BALANCE METHOD FOR PREDICTING
LEACHATE GENERATION FROM SOLID WASTE DISPOSAL
SITES", OSWMP, U.S. EPA, October 1975,
(EPA/530/SW-168)
-------
TABLE 3
RUNOFF COEFFICIENTS*
Surface conditions Runoff coefficient
Grass cover:
Sandy soil ,
Sandy soil,
Sandy soil,
Heavy soil,
Heavy soil,
Heavy soil,
flat, 2%
average, 2-7%
steep, 7%
flat, 2%
average, 2-7%
steep, 7% .
0.05
0.10
0.15
, 0.13
0.18
0.25
- 0.10
- 0.15
- 0.20
- 0.17
- 0.22
- 0.35
* Chow, V. T., ed. Handbook of applied hydrology; a
compendium of water resources technology. New York, McGraw-Hill,
[1964]. Iv. (various pagings).
Water Balance Calculations for a Sanitary Landfill
As shown in Figure 2, the water routing through a sanitary
landfill basically consists of two phases—routing through the
soil cover and routing through the compacted solid waste beneath.
The soil cover is that phase which interfaces directly with the
atmosphere and will determine the amount of infiltration into
the soil and percolation into the solid waste. The solid waste
phase and its attendant moisture storage capacity will determine
the quality and time of first appearance of the leachate.
Therefore, a water balance can be performed on the soil cover
phase to determine the amount of percolation. The solid waste
phase can then be analyzed in relation to the percolation amounts
to determine the extent of potential leachate problems.
Treating the moisture regime of the soil cover as a one
dimensional system, the water balance method can be used to
calculate the percolation of water into the solid waste. In
applying the method, the surface conditions of the sanitary
landfill site must be well defined. The type and thickness
of the cover soil, the presence or absence end type of vegeta-
tive cover, and the topographical features are the primary
surface conditions that will affect percolation.
8
-------
Actual
Evapotranspiration
(AET)
Precipitation (P) .,
^tX Vegetative
Surface Runoff (R/0) ' ^/ Cover
r ^- r
\V
Infiltration (I)
Soil Moisture Storage
Phase I
Phase IT
Figure 2. Sanitary Landfill Water Balance
-------
To best illustrate the water balance of a sanitary landfill. \
three case studies have been selected to reflect various climatic ,;
and soil conditions. Cincinnati, Ohio, was selected to represent
a humid climate with a sandy type soil; Orlando, Florida, to
represent a humid climate with a sandy type soil; and Los Angeles,
California, to represent a dry climate with a fine qrained soil. •.
Conditions will vary among sites and among the stages of
a given site's life. These conditions must be considered in
applying the water balance method. For illustrative purposes,
the water balance analysis was simplified by the following
basic assumptions:
1. The landfill has been completed with 0.6 meters (2 feet)
of final cover and graded with a 2 to 4 percent slope over most
of the surface area.
2. The solid waste, cover soil, and vegetative cover were
emplaced instantaneously at the beginning of the first month
of the computation initiation. Practically speaking, this
ignores any percolation that may occur prior to the placement
of the final cover soil.
3. The final use of the site is an open green area to be
used for recreation or pasture.
4. The surface is fully vegetated with a moderately deep-
rooted grass, the roots of which draw water directly from all
parts of the soil cover but not from the underlying solid waste.
5.* The sole source of infiltration is precipitation falling
directly on the landfill's surface. All surface runoff from
adjacent drainage areas is diverted around the landfill surface.
All ground water infiltration is prevented through proper site
selection and design.
6. The hydraulic characteristics of the soil cover and
compacted solid waste are uniform in all directions.
7. The depth of the landfill is much less than its horizontal
extent. Thus, all water movement is vertically downward.
The water balances for the three case studies are presented
and depicted in Tables 4, 5, and 6 and Figures 3, 4, and 5 for
Cincinnati, Orlando, and Los Angeles respectively. In order to
fully understand the calculations and manipulations involved in
the water balance procedure, refer to the Appendix which presents
the basic calculations, a discussion of each of the parameters
and their manipulations, and copies of the three soil moisture
retention tables used in the calculations.
10
-------
TABLE 4
HATER BALANCE DATA FOR CINCINNATI. OHIO
Parameter *
PET
P
c
R/0
R/0
I
I-PET
iNEG (I-PET)
ST (Table C)
AST
AET
PERC
J
0
80
0.17
14
66
466
150
0
0
+66
F
2
76
0.17
13
63
+61
150
0
2
+61
M
17
89
0.17
15
75
+58
*
150
0
17
+57
A
50
82
0.17
14
68
+18
<°)
150
0
50
+18
M
102
100
0.17
17
83
-1?
-19
131
-If
•
102
0
J
134
106
0.13
14
92
-42
-61
99
-32
124
0
J
155
97
0.13
13
84
-71
-132
61
-38
122
0
A
138
90
0.13
12
78
-60
-192
41
-20
98
0
S
97
73
0.13
9
64
-33
-22$
33
-8
72
0
0 N
51 17
65 83
0.13 0.13
8 11
57 72
+6 +55
39 94
+6 +55
51 17
0 0
D
3
84
0.17
14
70
+67
150
+56
3
+11
Annual
766
1025
154
872
+106
-
658
213
- — .
The parameters are as follows: PET, potential evapotransplration;
P, precipitation; CR/Q surface runoff coefficient; R/0, surface runoff;
I, Infiltration; ST, soil moisture storage; AST, change in storage; AET,
actual evapotranspiratlon; PERC, percolation. All values are in millimeters
(1 inch = 25.4 mm). See Appendix for discussion pf parameters.
11
-------
pnu
120,
100-
80
\
A M J j A S 0
MONTH
Figure 3. Water Balance for Cincinnati, Oh
Percolation g.
N
:Soil Moisture Recharge
/////Soil Moisture Utilization
10
InfiItration
A Actual Evapotransp?ration
12
-------
TABLE 5
II
HATER BALANCE DATA FOR ORLANDO. FLORIDA
Parameter *
PET
P
R/0
R/0
I
I-PET
XNEG (I-PET)
ST (Table A)
AST
AET
PERC
J
33
50
.075
4
46
+13
100
+9
33
44
F
39
56
.075
4
52
+13
100
0
39
13
M
59
91
.075
7
84
+25
W
100
0
59
25
A
90
88
.075
6
82
-8
-8
92
-8
96'
0
M
140
81
.075
6
75
-65
-73
47
-45
1^0
0
tj
J
/ -
167
161
.075
13
148
-19
-92
39
-8
156
0
..* J
175
230
.075
17
213
+38
-25*
77
+38
175
a
A
173
180
.075
13
167
-6
-31
73
-4
171
0
S
142
200
.075
15
«
185
v ....
+43
100
+27
142
16
0
100
121
.075
9
112
+12
100
0
100
12
H
53
39
.075
3
36
-17
-17
' 84
'-16
52
0
D
35
45
.075
3
42
+7
91
+7
35
a
Annual
1206
1342
100
1243
36
1172
70
*See footnote, Table 4.
*The situation where a positive I-PET value occurs between two negative
values Is a special case. Here, ST is found by direct addition of I-PET to the
preceding ST. TheiNEG (I-PET) value Is then found from the soil moiature
retention table for the ST value.
13
-------
210
180
150
120
M
M
J J
MONTH
Figure k. Water Balance for Orlando, Florida
IN I|III Percolation 6 0 Infiltration
So?1 Moisture Recharge
Moisture Utilization
14
£ Actual Evapotranspiration
-------
TABLE 6
MATER BALANCE DATA FOR LOS ANGELES. CALIFORNIA
Parameter*
PET
t-
C
R/0
R/0
I
I-PET
* SEC (I-PET)
ST (Table B)
AST
AET
PERC
J
. 34.
78
0.15
12
66
+32
52
+32
34
0
F
36
79
0.15
12
67
+31
83
+31
36
0
—^—^
H-
49
66
0.15
10
56
+7
-39
90
+7
49
0
A
S9
77
. 0
0
27
-32
-71 .-
70
-20
47
0
M
76
9
0
0
9
-«7
-138 •
40
-30
39
i
0
J
94
2
0
0
•<
7
-9?
-710
19
-21
23.
0_
J
117
0
0
0
0
-117
-147
7
-T7
12
g_
A
115
1
0
0
1
-114
-461
1
-4
5
0
8
96
u -,
5
0
0
1
-»1
-Vt?
1
-?
7
0
0
71
14
0
0
14
-S9
-611
. 1
0
14
0_
H
52
79
0
0
79
-?3
-614
1
0
29
0_
D
39
H ••
68
0.15
10
58
+19
20
+19
39
.0
Annual
840
378
44
334
-506
334
0
See footnote. Table 4.
-------
J J
MONTH
Figure 5- Water Balance for Los Angeles, California
Soil Moisture Recharge 6 3 Infiltration
Moisture Utilization &— -^Actual Evapotranspi ration
16
-------
Table 7 presents a summary of the water balances for the
three case studies. As expected, the locations in the humid
areas experienced percolation while the dry location experienced
no significant percolation: It is interesting to note that all
three cases are characterized by at least one wet season and one
dry season during the one-year cycle. However, only 1n the humid
areas is the precipitation sufficiently greater than the evapo-
transpiration to exceed the soil moisture storage capacity and
produce percolation.
The fluctuating nature of percolation during the one-year
cycle is an interesting phenomena to analyze. For example,
examine the percolation in Cincinnati. During the dormant season
(December to April), little or no evapotranspiration occurs,
resulting in a high soil moisture content and significant amounts
of percolation. During the growing season (Nay to September),
the large evapotransplratlon demand utilizes all of the Infil-
tration moisture. The effect of the soil moisture storage 1s
clearly seen in the fall months of October and November when the
infiltration exceeds the potential evapotranspiration. This
excess infiltration recharges soil moisture storage, resulting
in no significant percolation until December. The fluctuating
nature of percolation will cause variations in leachate generation.
Lcachate Generation
Knowing the amount of water that percolates through the
cover material (phase I), an analysis of the water routing
through the solid waste (phase II) can now be performed to
determine the magnitude and timing of leachate generation
(refer to Figure 2).
Like its cover material, the underlying, solid waste cells
(including the relatively thin layers of daily cover material)
will exhibit a certain capacity to hold water. The field capacity
of solid waste has been determined by many Investigators to vary
from 20 percent to as high as 35 percent by volume. •*»'* In other
words, the field capacity would vary from about 200 mm water/meter
refuse (2.4 inches/foot) to about 350 mm water/meter refuse
(4.2 inches/foot). For present purposes, a value of 300 on/meter
(3.6 inches/foot) will be used.
17
-------
TABLE 7
SUMMARY OF WATER BALANCE CALCULATIONS
Location
Parameters - mean annual (mm)
Precipitation Runoff Infiltration AET Percolation
Cincinnati,
Ohio
Orlando,
Florida
Los Angeles,
California
1025
1342
378
154
100
44
872 658 213
1243 1172 70
334 334 0
18
-------
The amount of water which can be added to the solid waste
before reaching field capacity depends also on its moisture
content when delivered to the landfill site. This value will
vary over a wide range depending on the composition of the waste
and the climate. Several analyses performed on municipal solid waste
show its n>Qi?*ure content to range anywhere from 10 to 20 percent
by volume.J''*'IJ A moisture content of 15 percent by volume
or about 150 mm/m (1.8 inches/foot) will be used here. Therefore.
with a field capacity of 300 mm/in and an initial moisture content
of 250 mm/m the compacted waste would have an adsorbtion capacity
of about 150 mm of water per meter of solid waste (1.8 inches/foot).
f
Theoretically, the water movement through a compacted solid
waste cell will act like water movement through a soil layer.
In other words, the field capacity of a given solid waste level
must be exceeded before any significant leachate to a lower level
will occur. For the examples, this means that 150 mm of percola-
tion would have to be applied to a municipal solid waste layer
one meter deep before any significant leachate would be generated
from the bottom of that layer. Practically speaking, due to the
heterogeneous nature of the solid waste, some channeling of water
will occur causing some leaching to occur prior to attainment of
field capacity. However, this amount should be small and certainly
not a continuous flow'and will be assumed negligible.
Employing the above concepts, one can assess the extent of
the leachate problem for a given sanitary landfill site. The time
of first appearance of leachate would be influenced by the land-
fill's depth and the leachate quantities by the landfill surface
area (size). Figure 6 shows the relationship between annual
percolation amounts and time of first appearance of leachate for
various landfill depths. Figure 7 shows the relationship between
annual percolation amounts and leachate quantities for various
size landfills.
• ',
This methodology will be illustrated by application to the
three case studies. Equal amounts of solid waste will be
assumed for all three cases in determining the relative depths
and acreage requirements at the different locations.
. Case 1--Cincinnati. Ohio. The landfills in this location,
as in most of the northern part of the country, are generally
trench operations or area fills in small ravines. The depth
of these operations would be expected to range between 10 and
20 meters, with the surface area usually above 50 acres (ca.
2X10V). A site will be assumed here with an average depth of
15 meters and a surface area of 202,000 mz (50 acres). Therefore,
with an average annual percolation of slightly more than 200 mm
-------
Figure 6. Time of First Appearance of Leachate *
300
200 '' — I —
§
•*«
s
100 .
Depth of Landfill (meters)
10
20
30
40
50
60
TIME (Yrs.f
+Based on a solid waste moisture absorption capacity of 150 mm/m.
Time zero is defined as that time when the field capacity of the
soil cover is first exceeded, producing the first amounts of percolation.
20
-------
Figure 7. Annual Leachate Quantities
After Tine of Rrst Appearance
300 • •
200 • — I - -f
rt
»-«
O
100
50
_. of Landfill
Surface (ra^x 104)
20 *« 60 80
Leachate Quantity (liters/year x 10*)
100
120
-------
(Table 4), it would take close to 11 years (Figure 6) for signi-
ficant amounts of leachate to appear at the bottom of the fill,
at which time the average annual leachat.p nuantitv wnnin KQ atinn
would be about
, Case 2--Orlando. Florida. The depth of landfills in this
location and most or the coastal United States are limited due
to proximity of the water table to the ground surface. The
regulations of most state agencies prohibit dumping of solid waste
directly into the ground water and, in fact, require a few feet
hnt^1SJU^ed,S°il-??tween the h19" 9round water level a"d the
w?ft°!.?f Jh? landfl11- Wl'th these restrictions, most landfills
will fin below ground only one or two meters and above ground
as high as availability of cover material will allow. Assuming
an average depth of 7.5 meters, only half the depth as Case 1,
A ?n§U5taceTarea rea.ui>ed W0"ld be doubled to 100 acres (ca.
?n m,|- Therefore, if the average annual percolation is
70 mm (Table 5), it would take close to 15 years for signifi-
cant amounts of leachate to appear (Figure 6), at which time
the average leachate quantity would be about 30 million liters/
year (Figure 7).
„ Case 3-Los Angeles. California. The landfills in this
?r" are generally area fills in deep canyons with depths ranging
between 30 and 60 meters. Assuming an average depth of 40 meters,
the surface area required would only be about one-fourth that of
£ nJi'^-J 3C!;eS (ca- 5xl0^2)- As n°ted in Table 6, percolation
is negligible and one can easily assess the leachate problem as
being insignificant for such a location.
A summary of the results for the three case studies is
presented in Table 8.
Analysis of the sanitary landfill water balance calculations
presented above points out some very interesting aspects of leachate
generation of importance to the design engineer. These aspects
should be considered in the overall assessment of the oroblem
and may enter into the selection and design of leachate control
measures.
First, in most cases leachate generation presents a potential
problem principally in humid (low AET and high precipitation) areas
of the country. Therefore, except for those sites where irrigation
is utilized (discussed later), leachate problems will be virtually
nonexistent at sanitary landfills in arid parts of the country
22
-------
TABLE 8
THEORETICAL LEACHATE QUANTITIES
AND TIME OF FIRST APPEARANCE
Leachate
Time of first Average
Location appearance annual quantity
(years) , (liters/year) x 10
Cincinnati, Ohio 11 4O
Orlando, Florida 15 30
Los Angeles, California — 0
Second, there may not be a continuous flow of leachate throughout
the year. Percolation and generation of leachate will most likely
follow a pattern similar to that of the precipitation. This will
result in the major portion of the leachate being produced during
those months of significant percolation, with much lower flows
occurring during the rest of the year.
Third, there will be a variation in the leachate generation
pattern and amounts fron year to year. The water balance cal-
culations presented in this paper use mean monthly climatic values
determined over a 25-year period. However, a brief analysis of
precipitation data for any given location will Indicate significant
variations from year to year. So, while the average year might
indicate a relatively minor leachate problem requiring little
or no leachate control measures,'an above average year may result
in an entirely different assessment of the problem. Therefore,
the engineer may wish to base his design on monthly precipitation
values higher than the average values in order to provide a factor
of safety in the estimation of leachate flow.
Other Considerations
The above methodology is presented with the Intention of
being a basic tool for engineers in assessing and designing
sanitary landfills. The presentation was purposely kept straight-
forward since the concern was more to develop a clear understanding
of the basic concepts and methods involved rather than a full
scale design manual that would assess leachate problems for all
conditions in all areas of the country.
23
-------
B-l DIFFERENTIAL ATTENUATION
Precipitation percolates into materials deposited in a solid-
waste landfill and lixiviation (dissolving of
soluble components) produces a solution called leachate.
The landfill leachate under conditions where infiltration
is greater than runoff and evapotranspiration combined,
moves downward through refuse, and through underlying
soil and sediment until it reaches an impermeable layer
or ground water. In its journey, leachate traverses
three zones of geochemical activity with certain
characteristics which are shared and others which are
unique to each. The ensuing discussion will attempt to
describe some of the characteristics in each of the zones
and ways in which they interact with the constituents of
leachate.
3.5.1 REFUSE ZONE
Solid waste deposited in municipal landfills is a
heterogeneous mixture of organic and inorganic materials
and living organisms. Upon deposition, and frequently
before, microbial activity begins the degradative process
on organic matter. The microbial decomposition of organic
3-37
-------
matter is encouraged by moisture and warm temperatures.
Moisture is provided through precipitation, and temperature
increases from the release of energy from oxidation of the
organic substrate. Temperatures as high as 120°F have
been observed in sealed test cells filled with mixed refuse.
Under aerobic conditions temperatures as high as 190°F have
2)
been observed.
The microbial activity soon uses up the supply of oxygen and
causes the refuse beyond the zone of rapid air diffusion
to go anaerobic. Anaerobic conditions cause the end
products of decomposition to be somewhat different from
carbon dioxide and water which are the products of complete
oxidation. Notable among the products of anaerobic
decomposition is methane gas. Other organic anaerobic
decomposition products such as alcohols, aldehydes, and
thiols tend to be more odoriferous than their aerobic
counterparts. Of particular importance with regard to
leachate are the anaerobic forms of sulfur, nitrogen, iron,
and manganese. Sulfur is present as sulfide, nitrogen as
ammonia, iron in the ferrous (+2) form, and manganese in
the manganous (+2) form. The latter two metals are more
soluble in their reduced forms than in their oxidized forms.
3-38
-------
The decomposition process provides carbon, hydrogen,
nitrogen, oxygen, sulphur, phosphorus, and some metals
which are fixed by microorganisms in their tissues.
Metabolic products and some inorganic residues from
organic decomposition are released to percolate.
The percolate flows downward through the refuse which is
in progressively advanced stages of decomposition, and
it passes through layers of buried cover material.
Percolate shows a net gain in dissolved constituents as
it progresses downward, but may lose some individual ions
from cation exchange or other reactions encountered en
route. Attenuation of percolate constituents within
the landfill is not well documented, therefore
predictions concerning it must be based upon known
geochemical principles and final leachate composition. The
attenuation within the refuse zone is not of immediate
practical importance because those species which are
attenuated are not contributing to ground-water
contamination. However, some discussion of processes
occuring in the refuse zone is important as it assists in
the interpretation of leachate composition.
Elements which are fixed in raicrobial tissue will not be
mobilized until the microorganisms die and the cells break
3-39
-------
down. Even then, some of the compounds released are only
slightly susceptible to further biodegradation, and
represent a stabilized organic material much like soil
humus, humus-like material is also a product of refuse
decomposition. This material is a polymeric organic
colloid with various chemically active functional groups,
such as acid, alcohol, and phenol, which can react with
metal cations to form complexes.
In this way, metals may be sorbed on the organic colloid
and removed from solution. Cation exchange reactions occur
in a manner similar to the exchange reactions occurring
with clay which are discussed below.
Nitrogen present in refuse organic matter is released in
soluble form with microbial decomposition. In organic
substances, nitrogen is in a chemically reduced state.
With aerobic decomposition, the nitrogen is oxidized to
nitrate ion. Under anaerobic conditions, nitrogen is
released as amonium ion.
3 )
Aerobic: 2 CH CHNH COOH + 70 > 3CO2 + 7H2O + NO3 (1)
•3 £. £•
Anaerobic: 0.33 C H ON + 0.073 HCO" + 0.64 HO—£0.33
46 3 2
NHj +0.14 CH COO" +0.13 C H COO~ + 0.133
C H COO" + 0.193 CO (2)
3-40
-------
Anaerobic conditions are predominant in landfills. Thus,
most nitrogen in leachate is present as ammonium. Nitrate
which is formed aerobically may be reduced through
denitrification to molecular nitrogen when it passes
through anaerobic zones. The relatively small amount of
nitrate produced, coupled with probability of denitrification
explains the typically low nitrate concentration in leachate.
Nitrogen is released only if it is present in quantities
exceeding the nutritional requirements of the microbial
population effecting organic decomposition. The requisite
amount of nitrogen can be expressed in relation to carbon.
Carbon/nitrogen ratios up to about 10/1 will result in
nitrogen release. Above that, most of the nitrogen will
be fixed in microbial tissue. Fresh organic matter would be
expected to release nitrogen during decomposition, whereas
carbonized ash would not be.
Organic decomposition releases carbon dioxide in large
amounts under aerobic conditions, and in smaller amounts
under anaerobic conditions. The enrichment of the
interstitial gas in refuse by carbon dioxide results in
production of bicarbonate ion as follows:
3-41
-------
C02 + H2° '" " " H2C°3
H2C03 ;==— H+ + HC05 (4)
HC03 ^ H+ + C052 (5)
Only when the pH exceeds 9 does reaction (5) occur to
a significant extent, (about 20)percent. ' The production
of carbonic acid (4) is proportional to the partial
pressure of C02 in the atmosphere in contact with the water.
The carbonic acid ionization to bicarbonate ( 4) is
proportional to the carbonic acid concentration. Only a
small fraction of the carbonic acid in the system is
ionized.
Bicarbonate is frequently a major anion in leachate.
ecause of the reversible reactions (4) and (5), when
present, bicarbonate acts as a buffer and tends to prevent
large fluctuations in pH.
Other organic decomposition products include carboxylic
acids (acetic, isobutyric),phenols (phenol, p-cresol), and
amino acids (glycine, alanine) which can form ring complexes
(chelates) with heavy metals, rendering them soluble and
protected from adsorption.5'6^Movement of heavy metals with
percolate may be possible to a large degree because of such
3-42
-------
complexes (Figure 3-8 ). The distance over which chelated
metals move depends upon the chemical and biochemical
activity encountered. Some chelates change ionic charge
with changes in pH. Thus, if a change in pH in percolate
occurs, the chelates may be adsorbed or otherwise
deposited. Microbial decomposition of the organic portion
of the molecule leaves the metal cation behind where it is
prone to adsorption or precipitation. If the chelated
metal encounters no conditions which affect it, it will
be transported to the ground water.
Heavy metals in landfills are primarily in their metallic
state and are not soluble . The exception is with
deposition of soluble heavy metal salts either as solids or
in solution. These may come from certain industrial
activities such as electroplating or metal pickling. Most
heavy metals occur in solution as cations (positively
charged), but a few are usually present as anions (negative-
ly charged). Those usually occurring as anions are chromium
and vanadium. Included with heavy metals, but chemically
somewhat different are arsenic, boron, and selenium which
occur as anions.
A minor complement of heavy metals is present in the
combustible (decomposable) fraction of urban refuse. In
3-1+3
-------
Gerayhcv & MUler, Inc.
0
II
ADENOSINE- 0- P'
0
II
P-0
\ / c o
M I » \
I >"i ^
HC — 0 — M
HC 0
I
COO
FeOTDSALICYLATE TARTRATE
PHENOLIC PHOSPHATE ORGANIC ACID
— CHELATES —
CLAY MINERAL
REMAINDER OF
HUMIC COMPOUND
- INSOLUBLE CLAY-HUMIC COMPLEX -
AFTER STEVENSON AND ARDAKANI, 1972
Figure 3-8
tfLf,f „
*" " * f J *^
3-44
-------
this usage, minor means concentrations in parts per million
as contrasted with percentages as represented by metallic
wastes. These heavy metals in the decomposable fraction
are released when the organic matrix is decomposed.
Table 3-10 lists metal concentrations taken from refuse
sampled after segregatLorfor use as fuel in an incinerator-
electrical generator. Some of the combustibles are
completely resistant to microbial attack (certain plastics)
and others are only very slowly decomposed (certain
plastic and rubber types). Therefore, metal concentra-
tions may be higher in Table 3-10 representing total
combustion than they would be for a biochemical decomposition
which would be incomplete.
Iron and manganese are typically found in leachate in
concentrations exceeding those of normal ground water.^^10)?
The anaerobic percolate water can reduce these metals to
lower valence states which are more soluble. The iron and
manganese may be present as part of the refuse material, or
may be part of the clay or hydrous oxide component in soil
cover.
Sulfur under aerobic conditions is oxidized to the sulfate
ion. Under anaerobic conditions, it is soluble as sulfide,
3-U5
-------
TABLE 3-10 INORGANIC ELEMENTS IN THE COMBUSTIBLE FRACTION OF URBAN
REFUSE 8)
Major elements
Typical value,
weight percent
Range
weight percent
Aluminum
Calcium
Chlorine
Iron (°)
Magnesium
Phosphorus
Potassium
Silicon
Sodium
Sulfur
Titanium
Zinc
Minor and trace
elements
Antimony
Arsenic
Barium
Beryllium
Bismuth
Boron
Cadmium
Chromium
Cobalt
Copper * '
Germanium
Lead
Lithium
Manganese
Molybdenum
Nickel
Silver
Tantalum
Tin
Tungsten
Vanadium
Zirconium
1.1
.45
.4
.18
.10
.1
.07
4.0
.5
.2
.23
.10
45
50
22
13
15
30
7
195
230
3
85
19
16
4
—
50
13
10
0.4 - 1.6
.23 -1.0
.3- 1.5
.05- .65
.05 -. 77
.07 -.7
.03-. 20
1.0 -.10
.15-.86
.1 -.3
.07-. 50
.04-. 84
21-77
2
35-79
1
6 -44
7 -70
3 -68
10-175
2-17
29-450
4
110-1,300
2-4
50-480
13-28
4-49
1-16
4
33-95
20
7-70
1-70
Present also in the metallic state
3-46
-------
or may occur as hydrogen sulfide gas (H2s) which has a
rotten egg odor. Sulfate has been reported in leachate9*
and sulfide is probably present in some leachates, but its
detection presents analytical problems. Moreover, many
metals form insoluble sulfide salts which remove sulfide
from solution.
Phosphorus is released by decomposition of organic matter.
At the usual pH range of leachate, the H PQ^ and HPO^2 ions
are predominant. As discussed below, soils have a high
capacity for phosphate attenuation, whereas the refuse
material does not. The clays and hydrous oxides responsible
for attenuation comprise only a small fraction of the landfill
mass. Phosphate can be and frequently is produced in
substantial amounts in leachate. Fungaroli reported a
maximum of 130 ppm in leachate from an experimental lysimeter.
His reported concentration is about as high as has been reported,
but several others have reached several tens of ppm.12^
Effluents containing phosphate concentrations of this order of
magnitude discharged into surface water would be expected to
produce a rather severe eutrophication in the receiving waters.
Were leachate to enter ground water directly, it would almost
certainly contribute more phosphate than would percolate which
has passed through soil and an unsaturated zone.
3-47
-------
Water quality parameters which do not measure individual
chemical species include biochemical oxygen demand (BOD),
chemical oxygen demand (COD), total organic carbon (TOC),
color, conductance, and turbidity. The refuse zone provides
little, if any, attenuation of these characteristics;
instead, it usually increases them. Bacteriological
investigations of leachate are in progress at the
University of Illinois and in the EPA. Fecal coliform
and fecal streptococci have been observed in leachate,
and poliovirus was reported in leachate from a simulated
landfill.12^ The recent trend to use of disposable
diapers has increased the source of enteric bacteria in
solid waste. Another source in some areas is septage which
may be disposed of on landfills with little or no treat-
ment. 9) Sewage sludges from municipal waste-water treat-
ment plants are frequently dried on sand beds and dumped in
landfills also used for other municipal refuse.
Movement of bacteria and viruses within the landfill and
through the unsaturated zone is dependent upon the
porosity of refuse and underlying geologic formations.
Refuse may offer many paths through which water can travel
relatively unimpeded. If course sand and gravel or
fractured rock underlie the refuse, percolating water may
carry microorganisms with little or no attenuation except
for natural die off. These conditions, judging from
locations which have been studied, are the exception rather
3-48
-------
than the rule.
3.5.2 UNSATURATED ZONE
As used herein, the unsaturated zone is defined as the area
in soil or sediments between the bottom of the landfill
deposits and the water table. The distance can vary between
zero (refuse contacting ground water) to several hundred
feet. This zone is below what is usually considered
"topsoil" or the weathered, organic-matter-rich upper horizons
of most soils. At most landfill sites, topsoil has been
removed, and sometimes much subsoil also, prior to deposition
of refuse. The porous materials comprising the subsoil are
likely to be low in organic matter, have a sparse microbial
population, and may vary in permeability over a wide range.
For purposes of discussion, we will consider the unsaturated
zone to be 20 to 200 feet thick. This range allows
percolating water an opportunity to react chemically with its
environment before reaching ground water. Percolating water
has four options in passing through the unsaturated zone. It
can move virtually unchanged, can show a net gain of solute,
show a net loss of solute, or keep the same total ionic
concentration with a net exchange of ions. Since few soils or
sediments are chemically inert, changes in transported solute
are to be expected.
3-U9
-------
Chemical activity in the unsaturated zone is primarily
located at the surfaces of clay minerals and hydrous oxide
coatings. Silts exhibit a small amount of chemical activity,
and limited microbial activity may take place either from
the indigenous population or that transported from refuse.
Clay minerals which occur in soils and sediments are small
aluminosilicate crystals possessing a large specific surface
area. The crystal structure is such that clay particles
have a plate-like shape. Particle sizes fall in the range
of true colloidal particles,<2 urn. The clay colloids carry
a net-negative surface charge which results from internal
atomic substitution and ionization of surface hydroxyl (OH)
groups. The negative charge attracts cations from solution
and they are adsorbed at the clay surface by weak chemical
and electrostatic (van der Waals) forces. Cations can
exchange on the clays and the cation exchange capacity (CEC)
varies with clay type. The clay types in order of CEC are
kaolinite
-------
accomplished on an equivalent charge basis, e.g.
displaces 2 Na+. Ions of higher charge usually displace
those of lower charge in cation exchange reactions.
Cations will be removed from solution until either the
cation exchange capacity is reached, or the limit of
displacement reactions is reached. The limit of CEC can
range from nearly zero to probably not more than 60
milliequivalents per 100 g soil. Solution concentrations,
pK, and percolation rate affect the reactions quantitatively.
Thus, no quantitative predictions about attenuation can be
made without knowledge of specific site characteristics. It
should be noted that adsorption is not a permanent fixation.
Cations may be desorbed with changes in solution composition,
pH, or oxidation-reduction (redox) potential.
Divalent and trivalent cations include most of the heavy
metals. These are held more strongly than sodium, potassium,
or ammonium on the cation exchange complex. Griffin and
Shimp measured the attenuation by clay minerals of several
components of leachate. ' They rated attenuation as follows:
High Hg, Pb, Zn, Cd
Moderate Si, Mg, K, NH4
Low Na, Cl
None Ca, Fe, Mn
3-51
-------
The rating "none" is believed to be caused by desorption of
calcium from clay exchange sites and dissolution of iron
and manganese in clay crystals by leachate. Al, Cu, Ni,
Cr, As, S, and P04 were too low in concentration to be
rated.
Another source of cation adsorption and exchange is the
coating of iron and manganese hydrous oxides frequently
found on soil and sediment particles.14^ These coatings
exist in amorphous and microcrystalline forms with specific
surface areas of as much as 300 sq m/g. Cations adsorbed on
the surfaces of newly formed hydrous oxides may, with time,
be incorporated in their crystal structure. Cations thus
incorporated are fixed, and no longer exchangeable.
Surface charges on hydrous oxides are produced by oxygen
and hydroxyl groups. The surface charge is dependent on pH
and redox conditions. Therefore, the CEC exhibited by
hydrous oxides is pH and redox dependent. The CEC of
hydrous oxides approximates that of illitic clays (10-40 meq/
100 g). Because hydrous oxides are not a discrete fraction of
soil as clays are, CEC calculations come from laboratory
preparations.
Heavy metals are prone to sorption on hydrous oxide coatings
in soil. The hydrous oxides are frequently cited as so
3-52
-------
limiting metal solubility that agricultural deficiences
of copper, zinc, and cobalt occur. Attenuation of heavy
metals present in leachate is desired. In locations
virtually free of clay minerals, these coatings may be
present on sand grains giving the sandy formation some
ability to attenuate metallic ions.
Adsorption is only one mechanism for removing dissolved ions
from solution. Changes in the geochemical environment can
also affect solution equilibria. A transition from
reducing conditions in the landfill to oxidizing conditions
in the unsaturated zone can reduce the concentration of some
redox-sensitive species in solution and change the chemical
form of others. Iron and manganese will oxidize and
precipitate from solution, for example. If porosity will allow
bacterial movement, biochemical reactions involving leachate
constituents can proceed. Sulfide and ammonium can be oxidized
to sulfate and nitrate. Dissolved organic matter measured in
terms of BOD and COD can be reduced through microbial
decomposition. Some nutrient elements in the course of these
reactions will be incorporated in bacterial tissue and thereby
removed from solution until the bacterial cells die off.
Conversion of ammonium to nitrate changes nitrogen from a subject
to attenuation to a form which is not. Sulfide to sulfate
3-53
-------
oxidation is not expected to be as significant. Sulfide can
form insoluble precipitates with many of the heavy metals.
For this reason, it may not be present in more than trace
amounts in leachate. Microorganisms may also attack the
organic ligands associated with chelated and complexed metals.
Decomposition or absorption by microorganisms would remove
the metals from leachate.
Phosphate reacts with a variety of soil components forming
insoluble products. Calcium and phosphate react in
solution to form hydroxyapatite [Ca5OH(P04)3"J the least
soluble phosphate compound known. Iron, aluminum, and
manganese can also form virtually insoluble precipitates with
phosphate. These reactions lead to a strong attenuation of
phosphate when these metal ions are present in the unsaturated
zone.
B&uwer reports that in the Flushing Meadows high-volume
waste water recharge project, large amounts of phosphate have
been fixed in the unsaturated zone by chemical precipitation. '
Phosphate fixed in this way amounts to about 43,000 Ib/acre
(48,000 kg/ha) calculated as phosphorus, and it has enriched
the unsaturated zone several tens of feet below the basin
surface. This illustrates the potential for attenuation of
chemical reactions as well as the more often considered colloid
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surface reactions.
Although phosphate ions are negatively charged, they interact
with clays and hydrous oxides forming insoluble complexes.
These reactions may occur in either soils or subsoils. The
phosphate complexes are so insoluble that phosphate added in
fertilizer must be added in excess to compensate for fixation.
The presence of clay or hydrous oxides in formations beneath
landfills is valuable not only from the point of view of CEC,
but also the fixation capacity for phosphate.
Carbonate also reacts with calcium, magnesium, and some
heavy metals forming relatively insoluble compounds. The
solubilities vary according to metal species and pH as shown
in Table _^rll_. Calcareous deposits in the unsaturated zone
can be valuable in attenuating phosphate and heavy metals from
leachate. Because carbonate neutralizes acids, BOD and COD
present as organic acid may also be reduced. Some organic acids
form insoluble salts with calcium, and organic bases are less
soluble in alkaline solutions. Carbonate induced alkalinity
may change solubilities of heavy-metal chelates and lead to
deposition of heavy metals.
Redox potential considerations are particularly important in
the unsaturated zone. Because of this, a brief discussion of
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Table 3-11 CONCENTRATIONS OF METAL IONS FORMING
CARBONATES OR IN EQUILIBRIUM WITH CaCO3
(mg/l) 16)
PH
7.2
7.6
8.0
8.5
Co2+
124
76
48
28
Fe2+
1.04
0.64
0.40
0.23
Cd2+
0.0035
0.0021
0.0013
0.0008
Pb2+
0.0211
0.0083
0.0041
0.0013
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the concept of oxidation and reduction in water systems is
included. Reduction is the gain of electrons by a chemical
species; oxidation is the loss of electrons. Iron
chemistry illustrates a common water component which is
sensitive to redox conditions. It is reduced as follows:
Fe+3 (slightly soluble) +e~ > F^+2
(more soluble) (?)
Fe+2 + 2e > Fe° (metallic) (8)
The oxidation state of iron or other major redox sensitive
species in water in combination with the percentage
saturation of dissolved oxygen determines the redox potential
of water.
Redox potential in water is measured electrochemically with
gold or platinum electrodes and a pH/millivolt meter. The
voltage reading obtained for redox potential is termed Eh.
Eh values range from over one volt for highly oxidized
4)
systems to negative voltage values for reduced systems.
Ground water frequently exists at a low Eh potential in
comparison to surface water. The low Eh governs solubilities
(iron, manganese), chemical species actually in solution
(Fe+3, FeOH+2, FeO42), and governs certain geochemical
transformations (nitrification, sulfate reduction). Because
of these geochemical controls, it is important to determine
Eh when geochemical interpretations must be made.
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A comment on Eh determination is called for because, although
useful, this measurement on ground water is difficult to make,
Any exposure of the water to the atmosphere will instant-
aneously change the Eh value. This necessitates a closed
system from the pump to sealed electrode holder. Water must
also be pumped until the Eh stabilizes, which may require as
much as several hours pumping time depending upon rate of
discharge and subterranean conditions. An Eh determination
made without proper care can be worse than useless because
it will indicate conditions which, in fact, do not exist.
The unsaturated zone is influenced by the percolation of
leachate into it and simultaneously influences the leachate.
Water of low Eh first infiltrating into the unsaturated zone
of high Eh will become more oxidized while simultaneously
reducing substances in the unsaturated zone. A continued
percolation of reduced water may con«/erc what had been an
oxidized system into a reduced one. Or the percolate may
become oxidized if that capacity in the unsaturated zone is
greater. The degree of influence of reduced leachate on the
oxidized unsaturated zone and vice versa depends upon the .
reserves of material capable of oxidizing or reducing in the
unsaturated zone and leachate. The greater the distance
leachate travels between refuse and ground water, the better
the chance that the entire path through the unsaturated zone
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will not become reduced. Raising the Eh of leachate will
tend to attenuate some components in solution at the point
of exit of the refuse zone.
Leachate reaching ground water may as a result of the
geochemical conditions en route be depleted in. some
constituents and enriched in others as dictated by the
composition of the unsaturated zone and its overall affect
on Eh and pH. Distance of travel, speed of percolation,
flow-nonflow cycles, and leachate temperature are all
parameters controlling leachate quality.
3.5.3 AQUIFER ZONE
Concepts useful for describing surface water pollution are
generally not valid for ground water. Ground water move-
ment is described by Darcy's Law which states that velocity
is directly proportional to the permeability of the aquifer
and the hydraulic gradient, and inversely proportional to the
porosity. Ground-water flow velocities vary over a wide range,
with 5 ft/yr to 5 ft/day being typical. Highly permeable
outwash glacial deposits, fractured basalts and granites,
and cavernous limestone aquifers allow very much higher
velocities.
The generally slow velocity of ground water results in
laminar flow which exhibits different characteristics of
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mixing than does the turbulent flow usually associated with
surface streams. A water of different chemical composition
from ground water which is injected or percolated into
ground water tends to maintain its integrity and is not
diluted with the entire body of ground water. Instead, it
moves with the ground-water flow as a plume undergoing
minimal mixing. The plume shape is determined by the
physical characteristics of the aquifer. Porous media give
somewhat different shaped plumes from fractured rock or
cavernous limestone. Figures , , , ,3^^ Q^^, „
illustrate the paths of ground-water movement in various
hydrologic regimes. It is obvious that plumes of leachate-
enriched ground water in these environments would assume
different shapes.
Other hydrologic conditions further influence plume shape.
Hydraulic gradients going in more than one direction, such as
occur if ground-water mounding occurs beneath a landfill, will
spread leachate laterally, creating a plume wider than the
areal extent of the landfill. A vertical gradient is less
often encountered, but should it be present, leachate would
follow ground-water flow downward as well as horizontally.
Leachate may exert an influence on the shape of the plume
of contamination it produces. Almost universally, leachate
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temperature will be above ambient. It may be as much as 50° F
above the ambient ground-water temperature. Leachate may also
have a dissolved solid concentration sufficiently high to
increase its density over that of ground water. These
combined physical characteristics may significantly affect
the way in which leachate interacts with ambient ground water.
For example, one study in a highly permeable aquifer showed
that leachate sinks directly to the bottom of the aquifer
beneath the landfill.9* No natural vertical gradient was
measured where this phenomenon occurred.
Differential attenuation is defined as a reduction in
concentration of a dissolved constituent with distance along
the direction of water flow which is disproportional to
changes in concentration of other constituents. Differential
attenuation may result from chemical reactions which remove
the constituent from solution or from self destruction.
Apparent attenuation occurs from dilution by mixing with water
of lower constituent concentration.
Dilution may take place in ground water in two ways. One is
hydrodynamic dispersion, and the other is molecular diffusion.
Microscopic dispersion is mixing caused by the tortuous flow
of water around individual grains and through pores of various
sizes in a porous aquifer. Macroscopic dispersion is mixing as
water flows in and around heterogeneous geologic formations.
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Molecular diffusion operates on a much more restricted scale.
It is the diffusion of solute across a concentration gradient
from stronger to weaker. Diffusion is seldom possible to
measure in the field. There are mathematical formulas which
describe dispersion.
In order to calculate a dispersion coefficient, an intensive
investigation of the site over a period of time is necessary.
Hydraulic gradient, porosity, concentration gradients in the
plume, temperature, and measurement of solute movement are
all factors entering into the formula. The time during which
the plume has been in existence is also important. The extent
of the dispersion is a function of time. Forecasting a
future extent of the plume may require a mathematical modeling
program in which dispersion is only one of the characteristics
of the system.
Chemical interactions provide the greatest amount of
differential attenuation in the aquifer zone. Hydrous oxides
of iron, aluminum, and manganese or clay minerals present in
aquifers attenuate cations in the same way that they do in
soils or the unsaturated zone. Because hydrous oxide and clay
colloids are in constant contact with water in the aquifer, it
can be assumed that the exchange sites are saturated and
essentially in equilibrium with the ambient ground water.
Leachate-enriched ground water when contacting these colloids
will initiate cation exchange which results in desorption of
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cations which are less strongly held than those replacing them.
In this way, hydrogen, sodium, calcium, and magnesium may be
released into the aqueous phase by exchange with heavy metals
and other cations in leachate. High hardness values associated
with leachate plumes may be due in part to this ion exchange
phenomenon.
Chemical precipitation in the aquifer is possible if the
natural ground-water composition includes ions which form
insoluble compounds with constituents in leachate. A.I
example would be formation of hydroxyapctite with leachate
phosphate and calcium in ground water. Other precipitation
reactions may occur if geochemical conditions are encountered
in the aquifer which lead to changes in redox potential or pH.
Buffering reactions may change concentrations of bicarbonate,
carbonate, ammonium, and sulfur (I^S, HS~). Reserves of
hydrogen (acid) or hydroxyl (base) ions may be present in
ground water if it has unusually high or low pH. Clays and
hydrous oxides also are capable of releasing hydrogen ions from
exchange sites for reaction with dissolved species.
The third means of attenuation in aquifers is that termed decay.
Oxidation of organic compounds produces carbon dioxide and water
and eliminates the compounds. Radioactive species undergo
radioactive decay to stable daughter products. Some elements
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decay in terms of seconds and others lose half of their
activity in periods measured in thousands of years. Radio-
active materials should not be present in municipal landfill
leachate. Micro-organisms carried into the aquifer zone are
deprived of a good nutrient supply and are subjected to a
generally cooler temperature. This results in a lowering
of biochemical activity, frequently to the point of cessation.
Bacteria can quickly adapt to hostile conditions by
encysting and ceasing activity. They may remain inactive,
but viable in this form from days to weeks. Bacterial cells
are attracted to inorganic colloid surfaces and are also
subjected to physical filtration. These phenomena coupled
with natural die off, tend to reduce bacterial numbers rather
rapidly.
There are two additional complications in the interpretation
of ground-water quality in leachate plumes. One is the
variation in leachate concentration with time, and the other
is the discontinuous recharge of leachate which occurs in most
geographical regions.
Leachate production begins as soon as deposited refuse is
wetted to field capacity. The lag time depends upon local
climatic conditions and rate of refuse deposition. In an
active landfill, older organic matter is stabilizing while
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simultaneously new organic matter is beginning to ferment
and produce stronger leachate. The net effect is an
increasing leachate concentration from a given area, or an
increasing areal contamination, or both as long as the
landfill is active.
Leachate produced at the initiation of percolation through
the landfill is less concentrated than that produced after
several years' refuse accumulation. This leachate will be
found at the distal end of the plume of leachate-contaminated
ground water. The closer the sampling site to the la-idfill,
the more concentrated should be the contaminated ground water.
An increasingly concentrated leachate source in addition to
the factors of dilution and attenuation must be considered
in interpreting the results of sampling the plume. An
erroneously high value for attenuation or dilution may be
given if the variation in source strength is ignored.
The intermittent recharge occurring from most landfills also
complicates interpretation of leachate-plume configuration.
During summer months when evaporation frequently exceeds rain-
fall, little or no leachate may be produced. Ground water,
however, moves under the landfill at a relatively steady rate.
Thus, there will be variations in the volume and strength of
leachate reaching ground water during the course of time.
These variations will show in the leachate plume as variations
in total solute concentration. A sample taken from the plume
at any given time may represent a "high" or "low" in the
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intermittent recharge pattern. One way to visualize this
phenomenon would be to watch the response of a conductivity
probe in a well screen over time. As leachate-enriched
ground water moves past the point, conductivity will vary
with changes in dissolved solids concentration. The
variations may be noticeable only in time spans of weeks to
months. Again, this complicates efforts to calculate values
for dispersivity or dilution because concentrations vary from
factors other than aquifer characteristics.
A generalized summary of the susceptibility of leachate
constituents is provided in Table 3-12. The mechanism of
attenuation which affects each constituent is listed for the
zones through which leachate may pass. When data are
summarized in this fashion, only the principal mechanisms can
be cited. For example, no attenuation is listed for all of
the constituents in the refuse zone. This is not really true
as the previous discussion points out. However, quantification
is impossible, and there is a net output of most of the
constituents. Sulfate, nitrate, and ammonium are given
biochemical conversion alternatives. These ions are subject
to oxidation and reduction reactions which may convert or
eliminate them. Heavy metals are also prone to one or more
of the attenuation mechanisms, and may not be universally present
in leachage. Biochemical reactions were not listed for the
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Table 3-12
SUSCEPTIBILITY OF LEACHATE CONSTITUENTS TO DIFFERENTIAL
ATTENUATION
Attenuated Constituent
Chloride
Sulfate
Sulfide
Phosphate
Nitrate
Ammonium
Sodium
Potassium
Calcium
Magnesium
Heavy metal onions
(Cr7V. Se,B,As)
Heavy metal cations
(Pb, Cu, Ni, Z n7 Cd, Fe, Mn, Hg)
Organic nitrogen
COD
BOD
Volatile Acids
Phenols
MBAS
Refuse Zone
0
0-B
C
0
0-B
0-B
0
0
0
0
0-B
0-A-C
0
0
0
0
0
0
Un saturated Zone
0
0-B
C-B
A-C
0
A-B
0
A
A
A
0-B
A-C
B
B
B
B
A-B
A-B
Aquifer
0
0
C
A-C
0
A
0
A
A
A
0
A-C
0
0
0
0
0-A
0-A
0 = no attenuation
A = adsorption
B = biochemical degradation on conversion
C = chemical precipitation
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aquifer zone because biological activity is inhibited. In
places, biological activity may be significant in the
aquifer, but the amount and type cannot be predicted.
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of gas produced by decomposing refuse. Public
Works 99(11):86.
2. Stone, R., E. T. Conrad, and C. Melville. 1968. Land
conservation by aerobic landfill stabilization.
Public Works 99(12):95.
3. McCarty, P. L. 1971. Energetics and kinetics of
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Gould, ed. Anaerobic biological treatment
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Geol. Survey Water-Supply Paper 1473. 363 pp.
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J. Water Poll. Contr. Fed. 46 (7):1776-1791.
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Environmental Protection Agency SW-12 rg. 132pp.
and appendixes. "
12. U. S. Environmental Protection Agency. in press.
Summary report: gas and leachate from land
disposal of municipal solid waste. Cincinnati, Ohio.
13. Griffin, R. A., and N. F. Shimp. 1975. Interaction of
clay minerals and pollutants in municipal leachate.
Preprint for WateReuse, Proceedings of the second
national conference on complete watereuse. American
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14. Jenne, E. A. 1968. Controls on Mn, Fe, Co, Ni, Cu,
and Zn concentrations in soils and water: The
significant role of hydrous Mn and Fe oxides. Pages
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American Chemical Society, Washington, D. C.
15. Bouer, Herman, J. C. Lance, and M. S. Riggs. 1974.
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