United States Office of Solid Waste SW - 924
Environmental Protection and Emergency Response 1984
Agency Washington DC 20460
Solid Waste
vvEPA Solid Waste Draft
Leaching Procedure
Technical Resource Document
for Public Comment
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SOLID WASTE LEACHING PROCEDURE MANUAL
(SW-924)
Draft Technical Resource Document
for Public Comment
•"•-- . , :-ncy
Minols 60604
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
OFFICE OF SOLID WASTE AND EMERGENCY RESPONSE
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
March 1984
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DISCLAIMER
This report was prepared by B. C. Garrett, D. R. Jackson, W. E.
Schwartz, and J. S. Warner of Battelle Columbus Laboratories, Columbus, Ohio
under Contract 68-03-2970. The EPA Project Officer was M. H. Roulier of the
Municipal Environmental Research Laboratory, Cincinnati, Ohio.
This is a draft report that is being released by EPA for public comment
on the accuracy and usefulness of the information in it. The report has
received extensive technical review but the Agency's peer and administrative
review process has not yet been completed. Therefore it does not
necessarily reflect the views or policies of the Agency. Mention of trade
names or commercial products does not constitute endorsement or
recommendation for use.
U.& Environs; :'•.' " " :n Agency
ii
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and governmental concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of the environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is the first necessary step in problem solution;
it involves defining the problem, measuring its impact, and searching for so-
lutions. The Municipal Environmental Research Laboratory develops new and
improved technology and systems to prevent, treat, and manage wastewater and
the solid and hazardous waste pollutant discharges from municipal and commun-
ity sources; to preserve and treat public drinking water supplies; and to
minimize the adverse economic, social, health and aesthetic effects of pollu-
tion. This publication is one of the products of that research—a vital
communications link between the researcher and the user community.
This study examines a laboratory procedure for generating leachate from
hazardous industrial solid wastes. The procedure is designed to extract
solutes from solid wastes in concentrations representative of those expected
to occur in a waste disposal environment.
FRANCIS T. MAYO
Director
Municipal Environmental Research
Laboratory
iii
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PREFACE
Subtitle C of the Resource Conservation and Recovery Act (RCRA)
requires the Environmental Protection Agency (EPA) to establish a Federal
hazardous waste management program. This program must ensure that
hazardous wastes are handled safely from generation until final
disposition. EPA issued a series of hazardous waste regulations under
Subtitle C of RCRA that is published in 40 Code of Federal Regulations
(CFR) 260 through 265 and 122 through 124.
Parts 264 and 265 of 40 CFR contain standards applicable to owners
and operators of all facilities that treat, store, or dispose of
hazardous wastes. Wastes are identified or listed as hazardous under 40
CFR Part 261. The Part 264 standards are implemented through permits
issued by authorized states or the EPA in accordance with 40 CFR Part 122
and Part 124 regulations. Land treatment, storage, and disposal (LTSD)
regulations in 40 CFR Part 264 issued on July 26, 1982, establish
performance standards for hazardous waste landfills, surface
impoundments, land treatment units, and waste piles.
The Environmental Protection Agency is developing three types of
documents for preparers and reviewers of permit applications for
hazardous waste LTSD facilities. These types include RCRA Technical
Guidance Documents, Permit Guidance Manuals, and Technical Resource
Documents (TKD's). The RCRA Technical Guidance Documents present design
and operating specifications or design evaluation techniques that
generally comply with or demonstrate compliance with the Design and
Operating Requirements and the Closure and Post-Closure Requirements of
Part 264. The Permit Guidance Manuals are being developed to describe
the permit application information the Agency seeks and to provide
guidance to applicants and permit writers in addressing the information
requirements. These manuals will include a discussion of each step in
the permitting process, and a description of each set of specifications
that must be considered for inclusion in the permit.
The Technical Resource Documents present state-of-the-art summaries
of technologies and evaluation techniques determined by the Agency to
constitute good engineering designs, practices, and procedures. They
support the RCRA Technical Guidance Documents and Permit Guidance Manuals
in certain areas (i.e., liners, leachate management, closure covers,
water balance) by describing current technologies and methods for
designing hazardous waste facilities or for evaluating the performance of
a facility design. Although emphasis is given to hazardous waste
facilities, the information presented in these TRD's may be used in
designing and operating non-hazardous waste LTSD facilities as well.
IV
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Whereas the RCRA Technical Guidance Documents and Permit Guidance Manuals
are directly related to the regulations, the information in these TRD's
covers a broader perspective and should not be used to interpret the
requirements of the regulations.
This document is a first edition draft being made available for
public review and comment It has undergone review by recognized experts
in the technical areas covered, but Agency peer review processing has not
been completed yet. Public comment is desired on the accuracy and
usefulness of the information presented in this manual. Comments
received will be evaluated, and suggestions for improvement will be
incorporated, wherever feasible, before publication of the second
edition. Communications should be addressed to Docket Clerk, Room
S-212(A), Office of Solid Waste (WH-562), U.S. Environmental Protection
Agency, 401 M Street, S.W., Washington, D.C., 20460. The document under
discussion should be identified by title and number (e.g., "Solid Waste
Leaching Procedure Manual, SW-924").
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ABSTRACT
This manual is a technical guide on one method for providing data on
the quality of leachate from solid waste. It describes a batch leaching
procedure for use in the laboratory with various kinds of waste to
predict the composition of leachate from that waste under field
conditions. Methods, equipment, and sources of error are discussed along
with suggestions for interpreting the data. The method has not been
verified by comparison with field data on leachate composition.
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TABLE OF CONTENTS
Page
TITLE i
DISCLAIMER 11
FOREWORD ill
PREFACE iv
ABSTRACT vi
1.0 INTRODUCTION 1
1.1 PURPOSE OF STUDY 1
1.2 SCOPE OF MANUAL 1
1.3 BACKGROUND 2
2.0 GENERAL DESCRIPTION OF THE SOLID WASTE LEACHING PROCEDURE (SWLP).... 5
2.1 RATIONALE 5
2.2 ASSUMPTIONS AND EXPERIMENTAL PARAMETERS 5
2.3 VALIDATION 14
3.0 EXPERIMENTAL 16
3.1 APPARATUS AND MATERIALS . 16
3.2 REAGENTS 18
3.3 SAMPLING 18
3.4 LEACHATE GENERATION 19
3.5 ANALYSIS 23
4.0 QUALITY CONTROL 24
4.1 INTRODUCTION 24
4.2 LEACHATE GENERATION 24
5.0 CONVERSION AND INTERPRETATION OF EXPERIMENTAL DATA 26
5.1 DATA CONVERSIONS 26
5.2 INTERPRETATION 31
6.0 REFERENCES 32
APPENDIX A: SUPPLIERS 34
APPENDIX B: STATISTICAL EVALUATION OF SOLID WASTE LEACHATE DATA 36
APPENDIX C: COMPARISON OF LABORATORY AND FIELD LEACHATE COMPOSITION 42
vii
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FIGURES
Number Page
1 Amount of Calcium Leached from Assorted Waste/Soil
Mixtures 9
2 Amount of Chromium Leached from Assorted Waste/Soil
Mixtures 10
3 NBS-Design Rotary Extractor 12
4 EPRI/Acurex Rotary Extractor 13
5 Schematic Diagram of the Overall Solid Waste Leaching
Procedure (SWLP) 20
6 Constituent Profile for Sample Data in Table 4 29
TABLES
Number Page
1 Leaching Test Parameters and Suggested Experimental
Specifications 7
2 Conversion of Experimental Data 28
3 Time Required to Exceed Specific Extraction Sequence
for Selected Cap Permeabilities 31
viii
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1.0 INTRODUCTION
An assessment of the composition of leachate from waste entering a dis-
posal facility is useful in reviewing applications for hazardous waste
disposal permits. This assessment can provide guidance in designing waste
containment and leachate collection and treatment facilities.
This manual describes a solid waste leaching procedure and provides
guidelines for use of the procedure on various waste types. The use of this
procedure provides an estimate of leachable constituents and the amounts of
these constituents that will be released when the waste comes in contact with
water in the disposal facility.
1.1 PURPOSE OF STUDY
This procedure was designed to extract leachate having chemical charac-
teristics similar to leachate from the same waste placed in a disposal
environment. The procedure is intended to:
1. Characterize the leaching profile of solid waste samples
using repetitive leachings with distilled water.
2. Provide integrated data reflective of the type of waste
entering a disposal facility and the method of disposal,
e.g., landfilling.
3. Provide a cost-effective management tool for assessing
leachate quality from a wide variety of solid waste types.
1.2 SCOPE OF MANUAL
This manual was designed to be a technical guide on one method for
providing data on leachate quality from solid waste which can be used in
disposal facility design and permit review processes.
The manual is designed to be used with the series of Technical Resource
Documents (TRDs) which have been prepared on various aspects of hazardous
waste disposal for the U.S. EPA-Municipal Environmental Research Laboratory
(MERL). This series of TRDs provides technical guidance on moisture infil-
tration, waste decomposition, leachate generation, disposal facility liners
leachate transport and collection, and transport migration and attenuation.
The documents in this series are:
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TRD 1 Evaluating Cover Systems for Solid and Hazardous Waste
(SW-867). This document presents a procedure for
evaluating design of final covers on solid and hazardous
waste.
TRD 2 Hydrologic Simulation on Solid Waste Disposal Sites
(SW-868). This document provides a computer package
to aid planners and designers in predicting runoff,
evapo-transpiration, and infiltration through landfill
covers.
TRD 3 Landfill and Surface Impoundment Performance Evaluation
(SW-869). This document describes how to evaluate the
capability of various liner/drain designs to control
leachate release from landfills.
TRD 4 Lining of Waste Impoundment and Disposal Facilities
(SW-870). This document provides information and
guidance on the performance, selection, and installa-
tion of specific liners for various disposal
situations.
TRD 5 Management of Hazardous Waste Leachate (SW-871). This
document presents management options for controlling
and treating leachate.
TRD 6 Guide to the Disposal of Chemically Stabilized and
Solidified Wastes (SW-872). This document provides
basic information on stabilization/solidification of
industrial waste to reduce leaching and ensure safe
burial of waste.
TRD 7 Closure of Hazardous Waste Surface Impoundments (SW-873).
This document describes the methods, tests, and
procedures involved in closing a site to minimize
potential environmental hazards.
TRD 8 Hazardous Waste Land Treatment (SW-874). This document
presents and discusses a comprehensive land treatment
facility design strategy based on sound environmental
protection principles.
This manual will complement the TRD series by providing a means for gen-
erating a laboratory leachate similar in composition to that expected from
the waste under field conditions.
1.3 BACKGROUND
Difficulties experienced in the past with disposal of hazardous waste
can be partially attributed to a lack of knowledge concerning the leach-
ability, compatibility, and the long-term dissolution of various waste forms.
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Manifestations of past disposal practices dictate that these factors must be
included in evaluating modern hazardous waste disposal facilities. Accurate
and reproducible methods for generating and chemically characterizing hazard-
ous waste leachate are needed for the following purposes:
• Performance evaluation of leachate collection and
treatment systems for new and existing hazardous
waste facilities.
• Assessing the attenuation capacity of various soils
and clay minerals for solutes originating from land-
filled waste.
• Assessing the compatibility of hazardous waste with
earthen and synthetic waste pit liners.
• Developing worst-case scenarios for potential con-
tamination of groundwater resources.
In order to meet the above needs, a solid waste leaching procedure must
serve as a model leaching system which will reflect the long-term behavior
of the waste in a landfill environment. In addition to this technical
requirement, the leaching procedure must be easily performed by technically-
trained personnel and cost-effective in analyzing a wide variety of waste
types.
In contrast to the EPA Extraction Procedure (EP), which is required by
regulation for classifying waste as hazardous or nonhazardous, the Solid
Waste Leaching Procedure (SWLP) detailed herein serves only as a guideline
for generating leachate from waste. The actual procedure used by a waste
generator or other research personnel for generating leachate may deviate
from the SWLP when different assumptions and compromises are adopted. Those
groups using a different procedure should be prepared to demonstrate that
their procedure gives results that are equivalent to the SWLP or are more
appropriate for a specific site.
Use of a leaching procedure such as the SWLP dictates significant
technical compromises in the interests of simplicity, cost-effectiveness and
reproducibility. The most significant of these compromises being:
• A leaching procedure cannot completely anticipate all
the slow changes the aging process may induce in the
leaching characteristics of the waste in the landfill
environment.
• Chemical reactions which occur when leachate from two
or more segregated waste cells within a landfill inter-
act cannot be fully simulated by a single component
leaching procedure. However, leachate generated from
one waste cell type can be used as the leaching medium
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for a second waste cell type. This technique was not
investigated fully during the development effort that
went into preparation of this manual.
• The leaching procedure does not address physicochemical
changes in the waste initiated by microbiological
processes.
• The leaching procedure may be unsuitable for oily wastes that give
leachates having a water-immiscible organic liquid layer. This layer
will interfere with obtaining either reproducible or representative
leachate fractions.
• The hydrologic regime of the actual field disposal
environment (e.g., channeling) may be inadequately
addressed by a laboratory leaching procedure.
Although the above compromises may limit the level of interpretation of
data obtained from the SWLP, the following design features have been incorpo-
rated to increase the usefulness of the test:
• Distilled water is specified as the leaching media
to stimulate precipitation inputs to waste disposal
facilities.
• Multiple successive extractions are used to evaluate
the leaching capacity of the waste and to infer a
time-dependent leaching response.
• Reproducibility of test results is enhanced by the
mixing action of the rotary extractor.
• The addition of intermittent cover material can be
used to simulate the potential interactions that
affect the composition of leachate in a disposal
facility.
These design features can be contrasted with the EPA EP which has been devel-
oped for an entirely different purpose: classification of waste as hazardous
or non-hazardous categories. This purpose makes the EP definitional in nature,
while the SWLP is designed for evaluation purposes.
A prominent feature that distinguishes the EP from the SWLP is the
leaching medium. The EP specifies the use of an acetic acid solution as the
leaching medium. This solution may be appropriate for the EP, which was
developed in consideration of a worst-case scenario in which hazardous
waste is co-disposed with municipal solid waste, but seem inappropriate for
the SWLP, which was developed for performance evaluation of properly
engineered hazardous waste land disposal facilities from which municipal
solid waste would be excluded. Consequently, the SWLP recommends use of
distilled water as the leaching medium to simulate precipitation, which
would be the predominant liquid entering the fill.
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2.0 GENERAL DESCRIPTION OF THE SOLID
WASTE LEACHING PROCEDURE (SWLP)
2.1 RATIONALE
Considerable research effort has been expended in an attempt to develop
more effective leaching procedures for hazardous solid waste (1,2). Many
different procedures have been produced from these efforts. Several com-
plexities associated with developing an extraction test may account for the
diversity of procedures now available:
• Correlation of extraction results with on-site observations
are difficult, thus verification of extraction methods
against a field standard has not been achieved.
o Multiple experimental variables associated with leaching
tests, such as leaching media, time of extraction, and
type of mixing device, can be manipulated in combination
depending on the objectives of the investigator.
• Many waste types (e.g., tars) exist which respond in
different ways to a given leaching procedure, requiring
that changes be made in some aspect of the procedure to
accommodate the unusual characteristics of waste.
The documentation of the SWLP is the culmination of an intensive review
of existing extraction procedures and refinements in techniques tested under
laboratory conditions. The SWLP is similar to Procedure R of the Standard
Leaching Test (SLT) developed by Ham, et al. (1,3) in that both procedures
offer the feature of repetitive leaching of hazardous waste samples with
fresh aliquots of leaching media. The primary advantage of this feature
of the procedure is that an inference of the time-release of leachate can be
made. This feature is suggested for use by those researchers desiring a
prediction of the leachate composition as a function of time. Guidance is
provided for translating extraction sequence number of repetitive leachings
into geologic time for the same sample in a specific field environment.
2.2 ASSUMPTIONS AND EXPERIMENTAL PARAMETERS
Three assumptions related to the disposal facility have been made to
enhance extrapolation of results obtained from the SWLP to field conditions.
The assumptions are that:
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(1) the disposal facility practices monofill disposal, (2) the disposal site
is designed to isolate segregated wastes, and (3) site meteorological and
engineering data are available.
Monofill Disposal
Facilities may take a single type of waste (monofill) or may take a
variety of wastes. Current commerical hazardous waste disposal facilities
have adopted criteria for waste compatibility. Using these criteria,
wastes are segregated into isolated disposal cells to prevent intermingling
of incompatible materials. Even after segregation, a cell often contains a
number of different wastes. The SWLP has been designed to predict the compo-
sition of leachate from a single waste (monofill). Alterations of the pro-
cedure are possible to address waste mixtures of various types. For example,
leachate generated trom one type of waste could be used as the leaching
medium for a second type of waste. This.example would simulate one type of
waste being disposed on top of an existing waste cell.
Site Engineering
A disposal site qualified to accept hazardous waste must be engineered
to prevent entry of surface-water runoff from adjacent land and to prevent
waste leachate contact with groundwater. The SWLP uses distilled water as the
leaching medium to model the assumption that natural precipitation would be
the primary leaching medium at the disposal site.
Site Data
The user of this manual is assumed to have access to meteorological and
engineering data collected at the site where the solid waste will be disposed.
Meteorological data should include average and extreme monthly precipitation
volumes and precipitation composition. Engineering data needed are: (1) the
expected surface area and depth of the site, (2) the anticipated schedule for
disposal activities, and (3) the type of soil used for intermittent cover of
the waste. These site data are needed for adequate interpretation of the
test results.
The experimental parameters suggested for the SWLP are outlined in
Table 1 and are discussed in detail below.
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TABLE 1. LEACHING TEST PARAMETERS AND SUGGESTED
EXPERIMENTAL SPECIFICATIONS
Leaching Test
Parameter
Experimental
Specifications
Reference Section
Number
Sample
Contact Area/
Particle Size
Leaching
Medium
Temperature
Method of
Mixing
Time of
Mixing
Number of
Leachings
Per Sample
Solid to
Liquid Ratio
Solid waste + representative amount
of intermediate cover soil material
> 2
Surface = 3.1 cm /g or
Sized to pass a 9.5-mm sieve [or
Monolithic]
Water unless another medium can be
justified on a site specific basis
Room temperature
Rotary mixer (tumbler)
18 hours
Flexible. Four are suggested
1:10 (1 gram solid to 10 ml liquid)
2.2.1
2.2.2
2.2.3
2.2.4
2.2.5
2.2.6
2.2.7
2.2.8
2.2.1 Sample
A representative sample of the solid waste under consideration for land-
fill disposal is used together with a sample of soil if any is to be used in
the fill as intermittent cover material.
The use of soil in the leaching procedure is a unique feature of the
SWLP. This soil sould be of the same type and be present in the same
proportion as that encountered at the disposal site. The ability of soils
to alter the mobility of species in leachates is well known and has been
studied extensively for various types of soils and wastes. For example, the
extent to which trace inorganic constitutents of leachates are attenuated is
related to the amounts of clay and iron and manganese hydrous oxides in the
soil (4,5); and attenuation of organic compounds such as PCBs is directly
related to the organic carbon content of the soil (6). Furthermore, soil
type influences complexing agents and colloidal constituents present in a
leachate and soil mixture. Because of the importance of the amount of soil
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that is mixed with a solid waste, this procedure recommends including the
soil with the waste in the sample to be leached. A possible extension of
this procedure is to select the most desirable soil type and determine the
optimal proportion to mix with the waste to achieve greatest attenuation of
waste solute. Where the solid waste disposal protocol precludes the use
of soil during active filling, then no soil should be used with the solid
waste sample for leaching.
The effect of various waste/soil mixtures on the amount of constituent
that is leached is shown in Figures 1 and 2. These results were obtained
from leaching an electroplating waste and a soil taken from a commercially
operated industrial waste land disposal facility. Results for calcium
(Figure 1) indicate that the addition of soil lowered the equilibrium
concentration by 31% using a 50/50 mixture. Additions of soil to the waste
had a much greater effect on the attenuation of chromium (Figure 2) by
reducing the equilibrium concentration 65% using the 50/50 mixture in the
initial extraction sequence. This amount of attenuation implies that the
chromium is largely in the trivalent cationic form. In further extractions
(extraction sequence numbers 3-6) the chromium concentration tends to
increase slightly in combination with soil. This increase most likely is
due to chromium oxidation to the hexavalent anionic form which is not
highly attenuated by soil. Additional discussion of these results can be
found in reference 7. The significance of the results illustrated in
Figures 1 and 2 is that the effect of the soil mixed with the waste to form
an intermittent or final cover should be anticipated as part of a compre-
hensive site evaluation. Use of waste/soil mixtures during the leaching
test is one aspect of conducting this evaluation.
2.2.2 Contact Area/Particle Size
2
The contact area of the sample can be ^ 3.1 cm /g or sized to pass
through a 9.5-mm standard sieve as specified in the EP, unless the solid
waste is monolithic, i.e., composed of massive solidified material. This
requirement for contact area and particle size is designed to simulate the
likely conditions to be encountered in the field disposal environment due
to mechanical filling operations and weathering. Some wastes are naturally
monolithic. These wastes will not have their particle size reduced as this
would cause them to be more leachable than under field conditions. Any
waste passing the Structural Integrity Procedure (as described in reference
8) should be considered to be monolithic and will be tested as a whole
rather than at a reduced particle size.
2.2.3 Leaching Medium
Laboratory reagent water is suggested for use as the leaching medium.
The water should be free from interferences that might interact with the
sample and should conform to one of the grades of Reagent Water consistent
with Federal Test Method Standard No. 7916, as given in reference 9. The
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234
Extraction Sequence Number
Figure 1. Amount of Calcium Leached from
Assorted Waste/Soil Mixtures.
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160 -
234
Extraction Sequence Number
Figure 2. Amount of Chromium Leached from
Assorted Waste/Soil Mixtures.
10
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selection of water as the leaching medium is consistent with the assumptions
about disposal site design and monofill disposal (no contact with other
waste liquids).
2.2.4 Temperature
Although no data are available for determing how much temperature
differences may affect waste leaching, temperature is known to affect
solubility and reaction rates of many chemical compounds present in waste.
Although ambient air temperatures at land disposal sites may range from
extreme cold (-40°C) to very high (45°C), temperatures for the leachates
associated with these sites are likely to be less varied. Overlying cover
soil and waste layers have a dampening effect on temperature variations (10)
Consequently, the temperature of the leachate emerging from the bottom of a
disposal site is likely to be that of the waste/soil at the same depth.
Seasonal fluctuations in waste/soil temperature at various depths may be
obtained from disposal site meteorological data or can be measured during
preliminary site investigations. The temperature used in the leaching
procedure should be close to that expected for the site leachate, unless
data are available to show that temperature variances will have little
effect on leaching of the waste being studied.
2.2.5 Method of Mixing
Any mixing device can be used for this procedure that will impart
sufficient agitation to prevent stratification of the sample suspension
and bring into continuous contact with the leaching medium.
The method of agitating or mixing the sample suspension has been studied
to determine which method offers the best combination of ease of operation
and extent of liquid-solid contact. Several problems have been associated
with mechanical stirrers: (1) binding of the stirring blade by solid parti-
cles; (2) movement of the stirred vessel; (3) stalling of the stirring motor;
(4) uneven blade alignment; and (5) sample grinding (11). However, a stirrer
has been designed that in many cases eliminates or reduces these problems (12)
Ham et al. (3) investigated five methods of mixing: mechanical and
manual shaking; mechanical stirring; swing shaking (180° swing); and variable
pitch rotary mixing. Their results showed comparable levels for inorganic
constitutents using the various methods. However, their recommendation was
to use a rotary mixer because visual observations indicated that the other
mixers occasionally failed to wet the waste uniformly. A study completed
for the U.S. EPA comparing the operation of the stirrer and rotary mixer
(NBS-design tumbler) indicates the rotary mixer produces greater precision
than the stirrer (13). Examples of rotary extractors are shown in Figures
3 and 4.
11
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Figure 3. NBS - Design Rotary Extractor
12
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, Bonded
\ Foam Liner
Figure 4. EPRI/Acurex Rotary Extractor
13
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2.2.6 Time of Mixing
The recommended time of mixing is approximately 18 hours. The time
specified for each leaching ideally should allow solute equilibrium to be
attained. Due to the diversity of waste constituents, no specified mixing
time is likely to be satisfactory for all situations. Therefore, the specifi-
cation of leaching time has to be made out of consideration of factors other
than attainment of equilibrium. The recommended time of approximately 18
hours is normally convenient for laboratory scheduling and is consistent with
the time specified for other related leaching procedures (2,8).
2.2.7 Number of Leachings
A minimum of four leachings is suggested to allow definite trends in a
leachate constituent level (increasing, decreasing, or no change) to be
noticeable. The solid waste plus soil sample used for the four leachings
is retained pending the analyses of the filtrates and interpretation of the
results. In the event the results warrant further leachings, then the
leaching cycle can be started with the saved sample and can be continued
for as many repetitions as desired.
2.2.8 Solid to Liquid Ratio
The ratio of solid to liquid used for each leaching has been established
as 1 to 10 (1 gram per 10 ml). This ratio should provide both an amount
sufficient to wet the sample and an excess amount to allow sufficient liquid
for proper mixing and subsequent analyses. The solid to liquid ratio that a
solid waste will experience in-situ is highly site dependent and very
difficult to forecast precisely. In most cases, the ratio will be one of
a large amount of solid per unit volume of leachate. The specified ratio
does not truly reflect the likely field conditions; rather it is a workable
minimum amount that will still allow sufficient liquid for proper mixing and
constituent analysis.
2.3 VALIDATION
Leachate collected from an existing solid waste disposal site was
compared to leachate generated by the SWLP from corresponding samples of
solid waste (7). The purpose of this comparison was to assess the
effectiveness of the SWLP in representing leachate obtained under field
conditions. Results of this comparison indicated considerable disparity
between SWLP-generated leachate and the field-collected leachate. Factors
accounting for the observed discrepancies were:
• Non-uniform migration of solutes within the
waste profile in the field.
14
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o Limitations of the laboratory method in repre-
senting dynamic leaching processes occurring in
the waste environment, and
o Depletion of solutes within the waste profile prior
to sampling resulting in lower amounts extractable
by the SWLP.
For further information on this comparison of labortory and field
leachate composition see the description in Appendix C.
Results similar to those obtained in the SWLP validation study
described above were obtained in an unrelated study of the leachi
behavior of bituminous coal fly ash. In that study, Dodd et al
compared results from extraction procedures to interstitial solution
expressed from core samplings and groundwater from the saturated zone of
the fly ash disposal pit. Solute concentrations obtained from the two
extraction procedures were not generally in good agreement with
interstitial solution or groundwater attributed to the inadequacy of the
simplified laboratory leaching procedures to account for the complex
leaching behavior of the fly ash in the field environment.
The SWLP or similar laboratory leaching tests may or may not provide
a completely accurate representation of field-generated leachate. These
tests can still be useful in assessing the overall potential leaching of
hazardous constituents from a given waste. The use of the SWLP on more
waste types and correlations with field leachate will likely provide more
validation of the method and confirm how useful it is in evaluating
hazardous waste.
Considering the reasons advanced for the disagreement between
laboratory predictions of leachate composition and the composition
actually observed in the field it is likely that the most definitive
validation will be the comparison of leachate from a laboratory test with
leachate from the same waste freshly placed in the field. Such a
comparison would be further facilitated when the field conditions are
known in detail, particularly the depth of waste, density, and rate of
moisture infiltration into the waste.
15
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3.0 EXPERIMENTAL
3.1 APPARATUS AND MATERIALS
The apparatus and materials used in the solid waste leaching procedure
must be demonstrated to be free from chemical species that might interfere
with the analysis of the leachates at the minimum levels of detection. In
practice, the apparatus and materials chosen for use in the procedure must
be selected with concern for potential interactions between the laboratory
equipment and the waste-leachate solution. Examples of interactions to be
avoided by careful selection of equipment are:
• Dissolution of the solution container by the leachate,
as might happen with a hydrofluoric acid-containing
waste placed in a glass vessel,
• Preferential sorption of constituents out of the leachate
by the sample container or filtration unit, as might
happen with some organic compounds when contained in
polypropylene vessels, and
• Contamination of the leachate by constituents leached
from the sample container, as might happen with waste
leachates to be analyzed for nickel and chromium
contained in stainless steel vessels.
The following discussion is designed to guide the investigator in
selecting various items for use in the procedure. Specification of a particu-
lar manufacturer or model is for purposes of guidance only. Addresses of
suppliers referenced in this section can be found in Appendix A.
3.1.1 Extraction Apparatus
An extraction apparatus must avoid stratification of the sample of solid
waste and soil and the leaching medium which would inhibit adequate contact
between the sample and leachate. The type of extraction apparatus recommended
for this procedure is the rotary extractor or tumbler (Figures 3 and 4).
The extractor consists of a rack or box device to hold the sample containers,
which are rotated through 360° at approximately 30 revolutions per minute.
A six-place tumble extractor derived from a design by the National
Bureau of Standards is illustrated in Figure 3. This equipment may be
fabricated by the investigator or obtained commercially (Associated Design
and Manufacturing Company, model //3740-4-BRE [four-place tumbler] or model
16
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#3740-6-BRE [six-place tumbler]). A second type of six-place tumbler, shown
in Figure 4, may be fabricated by the investigator or obtained commercially
(Acurex Corporation, no model number available).
The tumbler bottles should be sized to fit the particular tumbler, such
as Wheaton model #348522 roller culture vessels or equivalent, 1.8 to 2.5
liter capacity, with an inert cap liner.
3.1.2 Separation Apparatus
Separation of the solid and liquid layers following the extraction of
the waste sample can be accomplished by a combination of settling and
filtering. Details on performing these manipulations can be found in
Section 3.4, which gives stepwise leachate generation instructions.
Filter Holder
The filter holder must be capable of supporting a 0.45 micrometer mem-
brane filter and withstanding the pressure needed to accomplish separation.
These units may be simple vacuum units (Millipore model #XX10-047-00;
Nuclepore model #410400; or equivalent). However, the units capable of
being pressurized up to 75 psi are more likely to be needed for the majority
of solid wastes (Millipore model //YT30-142-HW; Nuclepore model #420800;
or equivalent).
Filter Pads
Three sizes of filter pads are suggested for use in all filtrations.
(1) Coarse glass fiber prefilter pad (Millipore model
#AP25-042-00 or #AP25-127-50 or equivalent)
(2) Fine glass fiber prefilter pad (Millipore model
#AP15-042-00 or #AP15-124-50 or equivalent)
(3) 0.45 micrometer nitrocellulose membrane filter
(Millipore model #HAWP-047-00 or #HAWP-142-50
or equivalent).
3.1.3 General Labware
Analysis Sample Bottles
The sample bottles used for containing large amounts of waste or leach-
ate should be of suitable materials, such as glass for organic analysis or
polypropylene for inorganic analysis; and they should have a screw cap with
an inert liner, such as Teflon®.
17
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Sample Vials
Containers for samples for analysis of volatile organic constituents
should have approximately 40 ml capacity (Pierce Chemical Company model
#13075 or equivalent) and have a screw cap with a Teflon®-faced silicone
septum (Pierce model #12722).
3.2 REAGENTS
3.2.1 Leaching Medium
The leaching medium selected for general use in the SWLP is reagent
water (9). This water must be of sufficient quality that it is free of
organic and inorganic interferences at the minimum levels of interest in
the subsequent leaching and leachate analyses that will be performed. Water
is the recommended leaching medium because it is deemed the best general
leaching medium for simulating natural conditions. An acidic leaching medium
or a synthetic leaching medium having a multi-component mixture is not recom-
mended for use with this procedure unless justified on the basis of site-
specific information. In certain situations, such as the siting of the
potential landfill in an area known to have acid rains, a different medium
may be justified. No data are available on the effect of simulated or
actual acid rain on leachate composition.
3.2.2 Nitric Acid
Addition of trace metals analysis grade concentrated nitric acid (such
as J. T. Baker product #9598 or equivalent) until the mixture has a pH of
less than 2 is recommended for preservation of leachate samples after collec-
tion for analysis of inorganic constituents.
3.3 SAMPLING
3.3.1 Sample Collection and Handling
A representative sample of the solid waste and soil covered to be tested
should be collected using one of the methods described in reference 8. It
is particularly important that the sample be representative of the solid
waste as it occurs in a landfill environment.
A minimum sample of 5 kg should be collected and sent to the laboratory
in a sealed container or containers. The container must be of suitable
material such that it will not react with the waste. In many cases a poly-
propylene container will be inert to the waste and, hence, adequate for use.
However, the suitability of the container should be assessed in light of the
likely composition of the waste.
18
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3.3.2 Sample Preservation
Samples that are stabilized with regard to biological or chemical change
may be shipped and stored at room temperature. Samples that are not stabi-
lized and might undergo significant biological or chemical change at room
temperature must be maintained at 0-5°C, during shipping and storage. If the
stability of the waste or soil is uncertain or unknown, shipping and storage
of the waste at 0-5°C is recommended.
Leaching of samples should be initiated within one week of sample collec-
tion to preclude gross changes in sample composition with storage time,
unless the sample is known to be stable to potential changes in composition.
3.4 LEACHATE GENERATION
The overall flow scheme for the SWLP is shown in Figure 5. Detailed
laboratory procedures are outline below.
3.4.1 Extraction 1
Step 1 Mixture Preparation
Place a 100-g representative sample of the solid waste and soil that has
been prepared for testing (see comments in Section 2.2.1) in an extraction
vessel (tumbler bottle or equivalent container). Add one liter of leaching
medium (Section 2.2.8) to the extraction vessel.
Step 2 Tumbling
Tighten the cap on the vessel and mix by tumbling, using the rotary
extractor. Tumble for 18 (±2) hours at room temperature. Stop the rotary
extractor, remove the extraction vessel, and allow the mixture to settle
for 15 minutes.
Step 3 Sampling for Volatile
Organic Constituents
If a sample of the leachate is needed for analysis of volatile organic
constituents, the aliquot should be withdrawn prior to filtration. Obtain a
sample for volatile organic constituent analysis by completely filling a
40 ml sample vial with the leachate. Fill the sample vial in such a manner
that no air bubbles pass through the sample as the vial is being filled and
no air space remains in the vial. Seal the vial with a Teflon®-faced septum
and screw-cap. Store it at 0-5°C in an inverted position until the time for
analysis. The sample container should be labelled to include the date,
extraction sequence number, and an appropriate sample identification number.
19
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SOLID WASTE
SAMPLE
ADDITION OF >=
LEACHING MEDIUM
(DISTILLED H20)
ADDITION OF
INTERMITTENT
COVER MATERIAL
18-HR EXTRACTION
ON ROTARY
EXTRACTOR
SAMPLE FOR
VOLATILE ORGANICS
LIQUID/FILTRATE
FRACTION
CHEMICAL
ANALYSIS
REPEAT
EXTRACTION
A TIMES
SOLID/FILTER *
CAKE FRACTION
EXTRACTION NO. A
EXTRACTION NO. 1-3 (9-14
RETAIN
PENDING
RESULTS
RETAIN FOR
SUBSEQUENT
EXTRACTION
NO
END OF
PROCEDURE
SPECIFIED STEPS
OPTIONAL STEPS
STEP NUMBER IN TEXT
Figure 5. Schematic Diagram of the Overall Solid
Waste Leaching Procedure (SWLP).
20
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-------
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If a discrete water-immiscible layer is present, withdraw the layer using
a syringe with a wide-bore needle. Transfer the layer to a tared sample con-
tainer of suitable material, such as glass. Determine the mass of the layer
and analyze it separately.
Step 4 Separation
Assemble the filter holder and filter pads following the manufacturer's
instructions. Place the 0.45 micrometer nitrocellulose membrane filter pad
on the support screen of the filter holder. Add first the fine glass fiber
prefilter pad and place the coarse glass fiber prefilter pad on top of the
membrane pad, so that the coarse pad will be the one closest to the filter
cake.
After assembling the filtration apparatus, wet the uppermost filter pad
with a small portion of the liquid phase of the extraction mixture. Transfer
the remainder of the extraction liquid layer to the filtration unit. Take
care to avoid transferring much of the solid from the extraction vessel,
because substantial amounts of solid can clog the filter pads. Apply vacuum
or gentle pressure (10 to 15 psi) until all liquid passes through the filter.
Stop the filtration when all the liquid has passed through the filter
pads. If this point is not reached under vacuum or using gentle pressure,
then increase the pressure stepwise in 10 psi increments to a final maximum
pressure of 75 psi.
If liquid remains above the filter pads after 30 minutes of filtration
at 65 psi, halt the filtration by slowly venting the pressurizing gas. Be
certain to follow the manufacturer's instructions for venting a pressurized
filtration apparatus. Some liquid may be trapped in the vent port and may
be released. Care must be taken to direct the vent port away from laboratory
personnel. After venting, decant the liquid above the filter pads into a
suitable container. Place the top-most (coarse) prefilter pad plus any
solid/filter cake in a suitable container, such as the extraction vessel for
use in the next extraction. Replace the filter pads, placing the fresh pads
on the unit in the correct order, and resume filtering.
Repeat the process of replacing the filter pad as often as necessary
until all the liquid has been filtered. In each process, retain the top-
most (coarse) prefilter pad along with any solid/filter cake.
After halting the filtration, return the unit to atmospheric pressure by
either carefully breaking the vacuum or slowly venting the filtration
apparatus.
Step 5 Solid/Filter Cake
Retain the solid/filter cake after filtration for use in the next
extraction or pending the interpretation of the results obtained from the
procedure. Include the top-most (coarse) prefilter pad for all filtrations,
as stated in Step 4. Use tweezers made of or coated with an inert material
to break apart the filter pads prior to beginning the next extraction.
21
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Step 6 Sample for pH and
Inorganic Constituents Analyses
Transfer an aliquot of the liquid/filtrate from Step 4 to a suitable
container, such as a beaker. Determine the pH. If an analysis for inorganic
constituents is needed, add a minimum volume of nitric acid (see Section
3.2.2) to lower the pH to less than 2. Transfer the acidified sample to a
suitable container, such ac a screw-cap polypropylene bottle. Store at room
temperature prior to analysis. The sample container must be labelled
properly, to include the date, extraction sequence nup.ber, and an appropriate
sample identification number.
Step 7 Sample for Semivolatile
Organic Constituents Analysis
Transfer an aliquot of the liquid filtrate from Step 4 to be used for
semivolatile organic constituents analysis to a suitable container, such as
a glass bottle with an inert-lined screw-cap. Store the sample at 0-5°C
prior to analysis. The sample container must be labelled properly, to
include the date, extraction sequence number, and a appropriate sample
identification number.
Step 8 Remainder of Filtrate
Retain any remaining filtrate after samples have been removed for
analysis. After analyses are complete, dispose of the filtrate in accordance
with approved laboratory procedures for disposal of potentially hazardous
liquids.
3.4.2 Extraction 2
Step 9 Mixture Preparation
Place the solid/filter cake from Extraction 1 (Step 5) with the coarse
filter pad or pads in an extraction vessel. Add one liter of fresh leaching
medium to the extraction vessel.
Step 10
Repeat the process of Step 2 through Step 8 using the previously extracted
solid waste plus fresh leaching medium mixture.
3.4.3 Extraction 3
Step 11 Mixture Preparation
Place the solid/filter cake from Extraction 2 with the coarse filter pad
or pads in an extraction vessel. Add one liter of fresh leaching medium to
the extraction vessel.
22
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Step 12
Repeat the process of Step 2 through Step 8 using the previously
extracted solid waste plus fresh leaching medium mixture.
3.4.4 Extraction 4
Step 13 Mixture Preparation
Place the solid/filter cake from Extraction 3 with the coarse filter pad
or pads in an extraction vessel. Add one liter of fresh leaching medium to
the extraction vessel.
Step 14
Repeat the process of Step 2 through Step 8 using the previously
extracted solid waste plus fresh leaching medium mixture.
Step 15 Retention of Solid/Filter Cake
Retain the solid/filter cake from Extraction 4 pending a decision on the
need for further extractions.
3.4.5 Further Extractions
The need for further extractions is determined based on the interpreta-
tion of results. Depending on the amount of solid waste that is dissolved on
each extraction, the extraction of the same solid waste sample with fresh
leaching medium can be repeated until solute concentrations reach minimal
detection levels.
Step 16 Disposal of the
Solid/Filter Cake
After all laboratory testing has been completed, the solid/filter cake
should be discarded in accordance with approved laboratory procedures for
disposal of potentially hazardous wastes.
3.5 ANALYSIS
The samples collected for analysis should be analyzed by one of the
EPA-approved or EPA-proposed methods. These methods can be found in a
variety of references (1,15,16).
23
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4.0 QUALITY CONTROL
4.1 INTRODUCTION
Quality control for the solid waste leaching procedure involves two
aspects: (1) that the procedure is free of interferences and ensures relia-
bility of the results, and (2) that the procedure is monitored while underway
to ensure that the desired level of quality is being achieved.
Guidelines presented in this section are designed to help the investi-
gator fulfill these two aspects of quality control. The basic method used is
to process procedure blanks through the various steps in the procedure. These
blanks are analyzed to determine whether interferences appear. The analytical
results are used to either modify the procedure, to eliminate the source of
the interferences, or correct the solid waste sample results for background
levels. Replicate samples are processes to monitor the precision and accuracy
of the procedure.
At present, no hazardous solid waste reference material is available,
although reference materials for nonhazardous wastes do exist. Consequently
interlaboratory comparisons of results from using the procedure on a standard
reference material representing hazardous wastes are not possible.
4.2 LEACHATE GENERATION
4.2.1 Preliminary
Before any solid waste sample is tested using the solid waste leaching
procedure, demonstrate that the procedure is free from any analytical
interference by processing procedure blanks through the various steps.
QC Step 1 Mixture Preparation
Using a graduate cylinder, add one liter of the leaching medium to an
extraction vessel containing no solid waste sample.
QC Step 2 Tumbling
Tighten the cap on the vessel and mix by the rotary extractor or selected
alternative method. Mix for 18 (±2) hours at room temperature. Stop the
rotary extractor, remove the extraction vessel, and allow the mixture to
settle for 15 minutes.
2.4
-------
QC Step 3 Separation
Prepare the filtration apparatus by the method of Step 4, Section 3.4.1.
Filter the extraction mixture in the same manner as that to be used with the
solid waste samples.
QC Step 4 Sampling for Analysis
Remove aliquots of the procedure blank solution for each type of analysis
to be run on the solid waste sample (analysis for pH, inorganics, and volatile
and semivolatile organic constituents). If sampling for volatile organic
analysis is done, follow the method of Step 3, Section 3.4.1, for filling the
sample vial. Label all sample containers, to include date and appropriate
sample identification number.
QC Step 5 Results
Examine the results of the analyses and determine whether any interfer-
ences are present. Identify the likely sources of the interferences and
modify the procedure accordingly. Repeat the processing of a procedure blank
on the modified procedure until the interferences have been eliminated.
4.2.2 Sample Testing
QC Step 6 Procedure Blank
The procedure blank consists of the leaching medium with no waste added.
It is recommended that one procedure blank be processed for every batch or
every ten solid waste samples tested. Carry the procedure blank through the
same steps as the solid waste sample. Ensure that the procedure blank is
treated identically to the solid waste sample. Be certain to add the top-
most (coarse) prefilter pad from Step 4, Section 3.4.2, to the successive
blanks that are generated.
QC Step 7 Replicate Sampling
Triplicate analysis of solid waste samples is recommended to obtain a
standard deviation indicative of the variability associated with the
analysis.
25
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5.0 CONVERSION AND INTERPRETATION OF
EXPERIMENTAL DATA
5.1 DATA CONVERSION
Conversion of the experimental data obtained in the leaching experiments
is necessary to predict the waste leaching characteristics under field
conditions. For interpretative purposes, the experimental data can be
related to concentration and mass of released waste constituents; or with
pertinent assumptions, as the constituents release into leachate as a
function of time. Statistical treatment of these data is shown in Appendix B.
5.1.1 Concentration and Mass Release Conversions
Conversion of the experimental data generated by the implementation of
the SWLP can be made in terms of (1) concentration of constituents in leachate,
(2) the mass of constituents released from each extraction, and (3) the cumu-
lative mass of released constituents. The following discussion describes
methods and examples for converting data into each of the above forms.
5.1.1.1 Calculation of Concentration
The data obtained using this SWLP can be used directly in terms of the
concentration of the constituent that was found on analysis of the leachate
solution. The general method of calculating this concentration is given in
Equation 1.
C(x). = C(anal). x DF Equation 1
In this equation, C(x)^ is the concentration of constituent x in the leachate
solution from extraction sequence number JL and has the dimensions of mass of
x per unit volume of leachate. C(anal). is the concentration of x that was
found on analysis. DF represents the dilution factor or concentration factor
for the analysis. The dilution factor gives the extent to which the leachate
solution was diluted or concentrated prior to analysis.
26
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5.1.1.2 Calculation of Mass
Released Per Extraction
The mass of the constituent released from the solid waste sample for
each extraction can be calculated by the method given in Equation 2.
C(x)
M(x). = Equation 2
1 O * Li
In this equation, M(x). is the mass of constituent x that was released from
the solid waste sample during extraction sequence number ^. The term S:L is
the solid to liquid ratio used in the extraction. The volume in the denomina-
tors of both C(x)^ and S:L must be in the same units, such as liters or milli-
liters so that these units will cancel. The term M(x)^ will then have the
dimensions of mass of x released per unit mass of solid waste, such as mg of
x per g of waste.
5.1.1.3 Calculation of Cumulative
Mass Released
The data can be used to calculate the cumulative mass of a constituent
released from the solid waste during a series of extractions. The general
method for calculating cumulative mass released is given in Equation 3.
n
M(x) = Z M(x). Equation 3
cum . , i
1=1
In this equation, M(x) is the cumulative mass of constituent x per unit
mass of waste that was released over the number of extractions (n). An
example is presented in Table 4.
5.1.1.4 Compilation of Concentration and
Mass Release Calculations
A data set of concentration and mass release calculations for a series
of four extractions on one waste sample is presented in Table 4. These data
are representative of data obtained during experimental development of this
leaching procedure.
27
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TABLE 2. CONVERSION OF EXPERIMENTAL DATA
Extraction
Sequence
Number
1
2
3
4
(mg/1)1
4.6
3.8
2.8
2.0
DF
2.0
1.0
1.0
0.5
C(x)i
(mg/1)
9.2
3.8
2.8
1.0
M(x)t
(mg/g)
0.092
0.038
0.028
0.010
M(x)cum
(mg/g)
0.092
0.130
0.158
0.168
The results calculated above can also be presented graphically. The
graphs can be prepared to show the extraction sequence number versus either
the concentration of constituent in the leachate solution or the mass re-
leased from the solid waste. Examples of graphing of results are shown in
Figure 6 which presents the data from Table 4.
5.1.2 Calculation of Time
Required for Leaching
The amount of time required in the field to collect a volume of leachate
comparable to that in each leaching sequence can be computed from the experi-
mental data assuming the following:
• Primary leachate volume is disregarded.
• Water infiltration rate through waste is constant, con-
trolled by the permeability of the cap material, and is
independent of the pore space of the waste.
• Depth of waste is fixed and known.
• The concentration of solutes in the waste does not change
over time.
• Waste is a monofill and is saturated with water at the
time of disposal.
Some wastes, as disposed, contain interstitial liquids having high concen-
trations of solutes which may be displaced as undiluted leachates early in
the leaching process. This leachate has been classified as primary in con-
trast to secondary leachate which is reflective of solutes dissolved in
perculating water of external origin, such as precipitation (17).
28
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5.0
X
u.
O
iu -^
81
8
2.5
0.10
uj
*"» * EM
° 5 1 0.05
oc £
ui
a.
>O
I
I
2 3
EXTRACTION SEQUENCE NUMBER
I
I
1234
EXTRACTION SEQUENCE NUMBER
Figure 6. Constituent Profile for Sample Data in Table 4.
29
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Based on these assumptions, the equation for calculating the time correspond-
ing to each leaching fraction is presented below.
where:
LT = (DW . p
LT
DW
Pwaste
LSR
CP
pwater
waste
LSR) * (CP
Pwater'
Equation 4
Leaching time (years to exceed leaching sequence)
Depth of fill (m, ft)
Density of waste (g/cm3, Ib/ft )
Liquid to solid ratio of SWLP
Permeability of cap material (cm/sec, ft/year)
Density of water (g/cm3, Ib/gal)
A representative case has been devised to illustrate use of this equa-
tion. Let:
DW
Pwaste
LSR
CP
Pwater =
LT
6.1 m (20 ft)
1.3 g/cnT (74.7 Ib/ft3)
10
1x10 cm/sec (IxlO"1 ft/yr)
lxlO~7 ml/sec'cm2 (0.77 gal/yr'ft2)
1.0 g/cm3 (8.39 Ib/gal)
(20 ff74.7 Ib/ft3'10) v (0.77 gal/yr'ft2'8.39 Ib/gal)
2,000 years
Thus, the leaching time in the field corresponding to the first leaching
sequence is 2000 years using the 1x10 cm/sec permeability value.
The usefulness of this computation is illustrated in Table 3. Calcula-
tions are presented for four leaching sequences and five cap permeability
values. For example, the time corresponding to the first extraction sequence
ranges from 20 years to 200,000 for cap permeabilities of 10~5 cm/sec and
10~° cm/sec, respectively, at a depth of waste fill of 6.1m. The results
of these time calculations, as shown in Table 3, demonstrate the extremely
long time (in terms of landfilll life) associated with each extraction
sequence. In most cases, the initial extraction sequence will provide the
leachate fraction of prime interest. These calculations presume that the cap
permeability determines the flow of leachate through the fill.
30
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TABLE 3. TIME CORRESPONDING TO SPECIFIC EXTRACTION
SEQUENCE FOR SELECTED CAP PERMEABILITIES
(DEPTH OF WASTE = 6.1m (20 ft))
Time Corresponding to Sequence at Selected Cap Permeabilities
Sequence —^-r ' —r2 * — f —
Number 10 cm/s 10 cm/s 10 cm/s 10 cm/s 10 cm/s
1
2
3
4
20
40
60
80
200
400
600
800
Years
2000
4000
6000
8000
20,000
40,000
60,000
80,000
200,000
400,000
600,000
800,000
5.2 INTERPRETATION
In general, the interpretation of the results involves comparisons of
the concentration of mass-released profiles of the various constituents that
have been examined. The Technical Resource Documents (TRDs) discussed in
Section 1 provide guidance on leachate flow rate calculations (see in partic-
ular TRD2, "Hydrologic Simulation on Solid Waste Disposal Sites [SW-868],"
TRDS, "Landfill and Surface Impoundment Performance Evaluation [sW-869]," and
TRD5, "Management of Hazardous Waste Leachate [SW-87l]"). These documents
plus the studies on leachate generation by Houle and Long (18,19) are
additional sources for information on calculations and interpretation of
leachate test data.
The profile illustrated in Figure 6 may be encountered when the con-
stituent is steadily depleted from the solid waste. Each subsequent extrac-
tion releases more of the constituent, although the mass released per
extraction decreases with each extraction. Other profiles that might be
encountered would show such trends as (1) a steady release where each
extraction releases essentially the same amount and (2) a delayed release
where initially little or none of the constituent was released, followed by
large increases in the amount released when alkalinity is leached and pH
decreases allowing metals to go into solution.
A decision regarding the need for further extractions will depend on the
profiles obtained for the initial sequence of extractions plus the specific
needs of the research being conducted. The application of the results to
events in a landfill environment depends on site specific information such
as infiltration rate for rainfall, the permeability of the waste, and the
density of the waste.
31
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6.0 REFERENCES
1. Ham, R. K., M. A. Anderson, R. Stanforth and R. Stegmann. The Develop-
ment of a Leaching Test for Industrial Wastes. In: Land Disposal of
Hazardous Wastes, Proceedings of the Fourth Annual Research Symposium,
San Antonio, Texas, March 6-8, 1978. EPA-600/9-78-016, U. S. Environ-
mental Protection Agency, Cincinnati, ohio, 1978. pp 33-46.
2. Lbwenbach, W. Compilation and Evaluation of Leaching Test Methods,
EPA-600/2-78-095, U. S. Environmental Protection Agency, Cincinnati,
Ohio, 1978. Ill pp.
3. Ham, R., M. A. Anderson, R. Stegmann, and R. Stanforth. Background Study
on the Development of a Standard Study on the Development of a Standard
Leaching Test, EPA-600/2-78-109, U. S. Environmental Protection Agency,
Cincinnati, Ohio, 1979. 274 pp.
4. Fuller, W. H. Investigation of Landfill Leachate Pollutant Attenuation
by Soils, EPA-600/2-78-158, U. S. Environmental Protection Agency,
Cincinnati, Ohio, 1978. 239 pp.
5. Griffin, R. A., and N. F. Shrimp. Attenuation of Pollutants in Municipal
Landfill Leachate by Clay Minerals, EPA-600/2-78-157, U. S. Environmental
Protection Agency, Cincinnati, Ohio, 1978. 157 pp.
6. Griffin, R. A., and E. S. K. Chian. Attenuation of Water-Soluble Poly-
chlorinated Biphenyls by Earth Materials, EPA-600/2-80-027, U. S.
Environmental Protection Agency, Cincinnati, Ohio, 1980. 101 pp.
7. Garrett, B. C., J. S. Warner, M. P. Miller, and L. G. Taft. Laboratory
and Field Studies of Factors in Predicting Site Specific Composition of
Hazardous Waste Leachate. In: Land Disposal of Hazardous Waste:
Proceedings of the Eighth Annual Research Symposium. EPA-600/9-82-002,
U. S. Environmental Protection Agency, Cincinnati, Ohio, 1982. pp 67-86.
8. Office of Solid Waste, Test Methods for Evaluating Solid Wastes, SW-846,
U. S. Environmental Protection Agency, Washington, D. C., 1980.
9. ASTM D1193-77. 1980 Annual Book of Standards, Part 31: Water, American
Society for Testing Materials, Philadelphia, Pennsylvania.
10. Fluker, B. J. Soil Temperature. Soil Sci., 86:35-46, 1958.
32
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11. Epler, J. L., et al. Toxicity of Leachates. IAG No. DOE-IAG-40-646-77/
EPA-IAG-78-D-X0372, Interim Progress Report to U. S. Environmental
Protection Agency, Oak Ridge National Laboratory, Oak Ridge, Tennessee,
1979.
12. Epler, J. L., et al. Toxicity of Leachates. EPA-600/2-80-057, U. S.
Environmental Protection Agency, Cincinnati, Ohio, 1980. 142 pp.
13. Warner, J. S., B. J. Hidey, G. A. Jungclaus, M. M. McKown, M. P. Miller,
and R. M. Riggin. Determining the Leachability of Organic Compounds
from Solid Wastes. In: Hazardous Solid Waste Testing: First Conference,
ASTM STP 760, R. A. Conway and B. C. Malloy, Eds., American Society for
Testing and Materials, 1981. pp. 40-60.
14. Dodd, D. J. R., A. Golomb, H. T. Chan, and D. Chartier. A Comparative
Field and Laboratory Study of Fly Ash Leaching Characteristics. In:
Hazardous Solid Waste Testing: First Conference, ASTM STP 760. R. A.
Conway and B. C. Malloy, Eds., American Society for Testing and
Materials, 1981. pp 164-185.
15. U. S. Environmental Protection Agency. Guidelines Establishing Test
Procedures for the Analysis of Pollutants: Proposed Regulations,
Federal Register, 44:69464-69575, 1979.
16. Kopp, J. F., and G. D. McKee. Methods for Chemical Analysis of Water
and Wastes. EPA-600/4-79-020, U. S. Environmental Protection Agency,
Cincinnati, Ohio, 1979. 460 pp.
17. Brown, K. W., and D. Anderson. Effect of Organic Chemicals on Clay
Liner Permeability. In: Disposal of Hazardous Waste: Proceedings
of the Sixth Annual Research Symposium, EPA-600/9-80-010, U. S.
Environmental Protection Agency, Cincinnati, Ohio, 1980. pp 123-124.
18. Houle, M. J., and D. E. Long. Accelerated Testing of Waste Leachability
and Contaminant Movement in Soils. In: Land Disposal of Hazardous
Wastes, Proceedings of the Fourth Annual Research Symposium, at San
Antonio, Texas, March 6-8, 1978. EPA-600/9-78-016, U. S. Environmental
Protection Agency, Cincinnati, Ohio, 1978. pp 152-168.
19. Houle, M. J., and D. E. Long. Interpreting Results from Serial Batch
Extraction Tests of Wastes and Soils. In: Disposal of Hazardous Waste,
Proceedings of the Sixth Annual Research Symposium, at Chicago, Illinois,
March 17-20, 1980. EPA-600/9-80-010. U. S. Environmental Protection
Agency, Cincinnati, Ohio, 1980. pp 60-81.
33
-------
APPENDIX A
SUPPLIERS
Addresses of suppliers having products mentioned in this document are
given for information purposes only. Mention of a particular product or
supplier does not constitute endorsement of that product or supplier.
Acurex Corporation
485 Clyde Avenue
Mountain View, CA 94042
(514) 964-3200
Associated Design and Manufacturing Company
814 North Henry Street
Alexandria, VA 22314
(703) 549-5999
J. T. Baker Chemical Company
222 Red School Lane
Phillipsburg, NJ 08865
(201) 859-2151
Balbab Incorporated
Division of Walter W. Platt Industries
6 Tinkam Avenue
Derry, NH 03038
(604) 434-4941
Millipore Corporation
Ashby Road
Bedford, MA 01730
(800) 225-1380
Nuclepore Corporation
7035 Commerce Circle
Pleasanton, CA 94566
(415) 462-2230
Pierce Chemical Company
P. 0. Box 117
Rockford, IL 61105
(815) 968-0747
34
-------
Wheaton Scientific
1000 North Tenth Street
Millville, NJ 08332
(609) 825-1400
35
-------
APPENDIX B: STATISTICAL EVALUATION OF
SOLID WASTE LEACHATE DATA
A statistical evaluation of experimental data generated from the SWLP is
imperative to ensure the quality of interpretive information obtained from
this procedure. As part of the development of the SWLP, a statistical model
was developed for the purpose of analyzing the various components of error
associated with the procedure.
Central to the concept of statistical evaluation of a leachate generation
method is the analysis of a leachate "profile." Conceptually, leachate pro-
duced from a waste disposal site changes in composition over time. This
process depicted in Figure B-l, where 6*(t) is a function representing the
activity of a chemical species. Laboratory analogs for producing this pro-
file, which would take several years in the field environment, are designed
to accelerate the release of chemical species through various extraction and
leaching procedures.
BMt)
Time (t)
FIGURE B-l. A TYPICAL LEACHATE PROFILE ASSOCIATED WITH A SOLID WASTE
36
-------
A leachate profile is characterized using the SWLP based on a series of
batch extractions. This laboratory extraction procedure involves subsampling
from a grab sample obtained from the waste, extracting the sample of waste,
filtering to obtain a liquid filtrate and a solid filter cake, and finally
analyzing the concentration of important analytes in the filtrate. The
leaching process is repeated several times using the filter cake obtained
from the previous trial to obtain a characteristic leachate profile for a
given waste sample.
There are several important sources of experimental variation which can
affect the results of this type of leachate generation method. Significant
variation may be associated with (1) subsampling the grab sample of the organ-
ic waste, (2) the extraction procedure, and (3) the chemical analysis process.
Sampling of the original waste is also recognized as a major source of experi-
mental variation. However, for the purpose of this discussion, it can be
assumed that a representative grab sample of the waste can be collected.
Objectives of the statistical analysis of data collected from an extrac-
tion method include:
(1) an estimation of the leachate profile function;
(2) a comparison of the leachate profile functions across
different types of waste; and
(3) estimation of components of variation associated with
waste sampling and extraction and chemical analysis.
These objectives can be accomplished through the use of a statistical
model which characterizes the data generated by the extraction experiments.
The statistical model is based on the assumption that a function g(k) exists
which, apart from uncontrollable experimental variation, determines the amount
of analyte extracted from a sample with each successive extraction (k).
The function 3(k) describes only the deterministic mechanism affecting
the leaching process at successive extraction number k. The complete statisti-
cal model also includes the error structure describing the important sources
of experimental variability, such as subsampling, extractions, and chemical
analysis. The level of detail required to completely describe the development
of the appropriate form for 3(k) and the error structure is too complex to
describe in this appendix.
A simplified version of the complete statistical model is a mixture of
fixed and random effects and is given by:
Y.. = 3(k) + S. + YM + e..
ikn i ik xkn
where
(1) Y., is the observation recorded for the nth analysis for the kth
extraction of the ith subsample of the waste;
37
-------
(2) S^ is the random error due to subsampling;
(3) Yk is the random error due to extraction; and
(4) e., is the random error due to chemical analysis.
This usual distribution assumptions for the random model components are:
S± ^ N (O.ag)
and
2
where X ^ N (y,a ) indicates a random variable distributed normally with
mean y and variance a .
Standard statistical techniques can be used to estimate the profile
function $(k) and the variance components
-------
240
180-
Chromium (M9/8)
120-
60-
\
TWO OR MORE DATA POINTS
I ONE DATA POINT
I I
2 4
Extraction Number
FIGURE B-2. LEACHATE PROFILE WITH DATA FOR 100% CHROMATE WASTE
39
-------
300
4.00
Extraction Number
6.00
FIGURE B-3. COMPARISON OF 100% LANDFILL SOIL
AND 100% CHROMATE WASTE PROFILES
40
-------
TABLE B-l. ESTIMATES OF THE VARIANCES COMPONENTS AND PERCENT
RELATIVE CONTRIBUTION FOR THE LANDFILL AND
100% CHROMATE WASTES.
ANALYTE
Boron
Barium
Calcium
Chromium
Magnesium
Sodium
Strontium
Zinc
"s
0.0
0.0329
0.0
0.0926
0.0
0.4618
0.0
C.i)
(%)
(0)
(4)
(0)
(9)
(0)
(4)
(0)
(0)
100% LANDFILL
°L m
1.648 (58)
0.7552 (95)
0.1086 (91)
0.5048 (47)
0.0273 (97)
6.690 (61)
0.0203 (97)
1.706 (78)
SOIL
a
e
1.197
0.0093
0.0101
0.4726
0.0008
3.802
0.0007
0.4790
m
(42)
(1)
(9)
(44)
(3)
(35)
(3)
(22)
100% CHROMATE WAS
"I
0.0545
0.0
0.0079
0.0007
0.0112
0.0
0.0065
0.0
(%)
(6)
(0)
(37)
(4)
(38)
(0)
(36)
(0)
°l
0.3922
0.2837
0.0134
0.0094
0.0177
7.726
0.0111
2.012
«)
(43)
(100)
(62)
(56)
(61)
(81)
(61)
(78)
TE
0
e
0.4680
0.0007
0.0003
0.0066
0.0003
1.760
0.0007
0.5588
(X)
(51)
(0)
(1)
(40)
(1)
(19)
(4)
(22)
This information is valuable in making comparisons between waste types
and analytes. For example, from Figure B-3 it is clear that the leaching
profiles for the landfilled and chromate wastes have similar shapes, but the
level of chromium extracted from the landfilled waste is much less than from
the chromate waste. Results in Table B-l indicate that, in general, the
greatest source of variability is due to the leaching procedure. In addition,
the contribution of the subsampling to the total variation in the data
appears to be greater for the chromate waste than for the landfilled waste.
Specific comparisons can also be made. For example, results shown in
Table B-l indicate that the error associated with the chemical analysis (a|)
for boron in the 100 percent chromate waste is significantly greater (51 per-
cent on a relative basis) than that for calcium (1 percent on a relative
basis).
41
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APPENDIX C
COMPARISON OF LABORATORY AND FIELD LEACHATE COMPOSITION
The material in this appendix has been taken from reference 7
"Laboratory and Field Studies of Factors in Predicting Site Specific
Composition of Hazardous Waste Leachate" by B. C. Garrett, J. S. Warner, M.
P. Miller, and L. G. Taft.
Because of the need for data showing what correspondence previals
between laboratory and field leachates, a study to provide samples allowing
comparisons to be made was undertaken. Field leachates and groundwater
samples were collected from an existing hazardous waste site, along with
solid samples from selected bore-hole sites and depths. These solid
samples were leached, and the laboratory and field leachates and
groundwater samples were analyzed and compared.
The waste disposal site was used from 1953 to 1977, with the primary
waste generator being a local manufacturer of Pharmaceuticals. The site
contains approximately 800,000 cubic meters (one million cubic yards) of
chemical fill and contaminated underlying soils. Major chemical components
estimated to have been disposed at this site are given in Table 1.
TABLE 1. ESTIMATED QUANTITIES OF MAJOR CHEMICAL COMPONENTS
DISPOSED AT LANDFILL SITE
Compound5 Kg
Arsenic 2,740,000
1,1,2-Trichloroethane 32,000
Nitrobenzene 130,000
Orthonitroaniline 680,000
Phenol 12,000
All but orthonitroaniline are priority pollutants
42
-------
EPA Region VII ordered the primary waste generator to cease dumping and
implemented remedial measures at the site. Among these measures was the
placement of monitoring wells along the site perimeters. These wells were
used during this study. The waste generator also drilled bore-holes into
representative areas of the fill to determine the feasibility of in situ
stabilization. Sites for these borings were chosen on the basis of prior
studies of the geohydrology and chemical fill composition of this site.
Core samples of chemical fill were obtained during the in situ
stabilization feasibility assessment drilling.
Materials
Three types of samples were collected from the landfill site.
Groundwater
Groundwater samples were collected by site personnel from five
monitoring wells: Well No. 4 - Alluvial, Well No. 6 - Alluvial Deep, Well
No. 7 - Alluvial Shallow, Well No. 7 - Alluvial Deep, and Well No. 9 -
Alluvial. Samples were stored at 4°C until prepared for analysis.
Chemical Fill Samples
Samples of the chemical fill were collected by means of a split spoon
sampler at various depths from five bore-hold sites. Solid materials were
transferred to glass containers, capped, and stored at 4°C pending
analysis. These samples were leached in the laboratory to provide the
laboratory leachate (see Procedure, below).
Field Leachate
Samples of leachate present with the waste fill were collected by means
of a bailer from the freshly drilled holes. Bailer samples and additional
bore-hole site information are given in Table 2. Four bore-holes provided
samples of field leachate; a fifth site had no liquid. All bore-holes were
capped followiing drilling and sampling.
Apparatus
Extractor
Chemical fill samples were leached using a rotary extractor (Associated
Design and Manufacturing Company, Model //3740-4-BRE)*, which tumbled the
sample plus water mixture in an end-over-end fashion.
*Manufacturers and suppliers are mentioned for identification purposes
only. Mention of a particular brand or model does not constitute
endorsement on the part of the U.S. EPA.
43
-------
TABLE 2. LANDFILL BORE SITES
Bore
Site
Distance
to
Bottom
of
Chemical
Waste
Date Drilled (ft)
Distance
to
Water
Table
(ft)
Depth
at
Which
Sample
(Bailer)
Taken
(ft)
Comment s
L-l-80 8 July 1980 23.5 22.5
L-2-80 7 July 1980 18.5
L-7-80 9 July 1980 26.5 14.5
L-8-80 8 July 1980 21.0 24.5
L-17-80 9 July 1980 13.0 23.5
23.0 Nothing remarkable
— Dry hole. No water,
even after tornado of
9 July 1980.
14.5 Copious amounts of
water present in the
core material
24.5 Nothing remarkable
29.5 Contained a strange
whitish clay-like
waste. Waste began
within 6 inches of
surfaces. Noticeable
nitrobenzene ("shoe
polish") odor from
bore site.
Filtration Unit
Following tumbling, laboratory leachate samples were filtered using
pressure filtration (Millipore Model #YT30-142-HW), in accordance with
manufacturer's recommended procedure. This procedure required use of three
types of filter pads: coarse glass fiber prefilter pad; fine glass fiber
prefliter pad; and 0.45 micrometer nitrocellulose membrane filter.
Groundwater and bailer field leachate samples were also filtered in an
analogous procedure.
44
-------
Inorganic Analysis
Filtrates from the laboratory leachate process and groundwater and field
leachate samples were prepared for inorganic analysis by the digestion
procedure given in Section 8.8.3, EPA Interim Method 200.7 (3). Digested
samples were analyzed on a Jarrel Ash Model 965 Inductively Coupled Argon
Plasma Spectrometer (ICAP). Low concentrations of arsenic were determined by
the hydride generation technique, using a Perkin-Elmer Model 603 Atomic
Absorption Spectrophotometer (AAS).
Organic Analysis
Samples were analyzed for organic constituents by gas chromatography (GC)
and gas chromatography/mass spectrometry (GC-MS). Listings of substances
suspected of having been disposed at this landfill site aided identification
of mass spectra. GC and GC-MS operating conditions were: SE-52 glass
capillary column, 30 meters long and with linear velocity of 50 cm/sec.
Column oven conditions were 70° to 280°C at 4°/min, then hold at 280°C
for 8 min. The gas chromatograph used as a Hewlett Packard Model 5730A
equipped with a flame ionization detector. The GC-MS system was a Finnigan
Model 3200 GC-MS/electron impact. Mass range of 40 to 450 mass units was
searched at a scan rate of 1 to 2 sec. Identification was aided by a
Finnigan/INCOS Library Search unit, using an MBS mass spectral library.
Leaching Procedure
Chemical fill samples from selected bore-hole depths were leached by the
following procedures:
1. An "instantaneous" leachate was produced by tumbling 100 g chemical fill
with 2.0 liters distilled, deionized water for approximately one minute.
This rapid leaching was done to remove interstitial liquid that might
represent field leachate that had migrated to, but was not characteristic
of, the particular sample being leached.
2. The filter cake remaining after the separation of the instantaneous
leachate through pressure filtration was leached by tumbling for 24 hours,
using approximately 100 g filter cake with 2.0 liters water. The precise
quantities of filter cake and water depended upon the amount of solid
material remaining after the instantaneous leaching; however, the ratio of
solid to liquid was maintained at 1:20 (w:v). This ratio was chosen to
conform to that of the RCRA Extraction Procedure. However, experience
gained since this work was performed suggests the use cf lower ratios,
such as 1:10 (2), is more appropriate.
45
-------
Results
The analyses of the groundwater, field leachate (bailer), and
laboratory-generated leachates are presented in Tables 3-6. Although the
results are varied, the overall lack of agreement among the data for the three
distinct sample types seems evident. This lack of correlation arises from
more than just the dilution effects for the sample types, because correlation
is also lacking within specimens of the same sample type, as shown by the
disparity in the ratio of arsenic to orthonitroaniline (see Table 3). Both
the concentrations and the multitude of constituents found differ between the
field leachate (bailer) results and the laboratory leachates (bore-hole
samples from similar depths), as shown for inorganic elements in Table 4 and
organic compounds in Table 6.
TABLE 3. LANDFILL SAMPLES CONSTITUENT PROFILE -
PRINCIPAL HAZARDOUS CONSTITUENTS
Sample
Identification
Constituent
Ratio
A. Well Samples
4A
6AD
7AS
7AD
9A
0.56
16
2.3
23
65
ND
3.9
0.59
4.5
18
18.2
232
140
382
336
33
15
61
17
5
(a) All results are in ppm (mg/1-solution)
(b) ONA = ortho-nitroaniline = 2-nitrobenzenamine
(c) PNA = para-nitroaniline = 4-nitrobenzenamine
(d) AS = arsenic
(e) As/ONA = ratio of As to ONA
ND = not detected
46
-------
TABLE 3. (Continued)
B.
1.
2.
3.
4.
5.
Sample
Identification
Bailer and Solid
Bore Site L-l
3 ft
14.5 ft
17 ft
Bailer (23 ft)
Bore Site L-2*
21 ft
22.5 ft
Bore Site L-7
1.5 ft
16.5 ft
18 ft
18.5 ft
21 ft
Bailer (14.5 ft)
Bore Site L-8
3 ft
17 ft
31 ft
Bailer (24.5 ft)
Bore Site L-l 7
9 ft
9.5 ft
21 ft
31 ft
Bailer (29.5 ft)
1st
ONA
2nd Liq
1st
PNA
2nd
Waste Leachate Samples
7.9
2.4
0.40
~
3.6
0.16
26
1.8
1.9
2.0
3.1
—
2.6
4.0
ND
—
ND
0.18
ND
ND
—
1.9
4.6
0.52 --
130
0.015 —
0.021 —
27
0.34 —
0.24 —
0.24 --
ND
16
1.1
0.30 ~
ND
14
ND
ND
ND
ND
0.81
0.075
ND
ND
--
0.24
ND
0.26
ND
ND
ND
ND
—
ND
1.5
ND
—
ND
ND
ND
ND
—
ND
ND
ND
--
ND
ND
0.32
ND
ND
ND
ND
—
ND
0.37
ND
~
ND
ND
ND
ND
—
Liq 1st
2.5
-- 101
2.6
4.4
14.2
2.3
7.2
68.4
35.6
41.2
27.1
ND
2.0
40.4
0.9
3.3
5.6
12.0
ND
ND
ND
As
2nd
1.8
141
8.4
—
1.4
4.0
14.2
48.4
24.8
35.9
21.1
~
3.4
8.1
1.4
—
4.2
5.6
ND
ND
—
ONAs/ONA
Liq
—
—
374
__
--
—
—
--
635
_.
—
—
284
__
—
—
64
1st
0.3
42
7
--
4
14
0.3
38
19
21
9
—
0.8
10
—
—
__
67
--
—
2nd
0.9
31
16
—
93
190
0.5
142
103
150
—
—
3
27
~
—
_ _
—
—
—
Liq
__
—
3
__
—
—
—
~
40
__
—
--
20
__
—
79
NOTE: All results are in ppm (mg/1-solution)
1st « leachate generated by washing with HgO for one minute, S:L «= 1:20 (H/V)
2nd = leachate generated by 24 hour tumbling with H^O, S:L = 1:20 (W/V)
Liq = liquid taken by means of the bailer
All other abbreviations are the same as part A above
* No bailer samples could be taken; dry bore hole
47
-------
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TABLE 5. LANDFILL SAMPLE CONSTITUENT PROFILE -
ORGANIC CONSTITUENT IDENTITIES
Five samples were analyzed by gas chromatography/mass spectrometry
(GC/MS). The five were well 9 alluvial (W9A); well 9 alluvial-acidified (W9A
(acid)); bailer from bore site L-8 (BL8); bailer from bore site L-17 (BL17);
and the second leachate from the solid waste of bore site 1-7 at 18.5 ft
(X217d).
The number of important peaks (peaks having a significant peak count area
and coming after the solvent peak) in the five samples ranged from five to
twenty. The GC/MS data and a list of substances likely to be in the wastes
were used to assign identities to the peaks.
Peak numbers are assigned according to relative retention times. Peaks
for separate analyses having nearly the same relative retention time are given
the same peak number. The identify of peak (9 for the well liquid samples
does not match that assigned for peak #9 in sample X2L7d, a solid waste
leachate.
Peak
No.
1
2
3
4
5
6
7
8
9
9
10
11
12
13
14
Peak Identity
aniline (benzenamine)
phenol
2-ethyl-l-hexanol
2-chloroaniline
2-nitrophenol
4—chloroniline
ortho-phenylenediamine
(1,2-benzenediamine)
2-chloro-4-methylaniline
2-butoxyethanol
l-chloro-2-methyl-3-nitrobenzene
ortho-nitroaniline (ONA)
2-methylbenzimldazole
para-nitroaniline (PNA)
dlphenylamine
2-chloro-4-nitroaniline
Samples for Which
Peak Was Confirmed by GC/MS
W9A, B18, BL17
W9A, W9A (acid), BL8
BL8, BL17
W9A, W9A (acid), BL8
W9A, W9A (acid), BL8
W9A (acid), BL8
W9A, BL8, BL17
W9A
W9A, W9A (acid)
X2L7d
W9A, W9A (acid), BL8, BL17, X2L7d
W9A
W9A, W9A (acid), BL8
W9A, BL8, BL17, X2L7d
W9A, W9A (acid)
49
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These results demonstrate that laboratory-generated leachates of
samples from an existing site cannot be used readily to gain an accurate
profile of the field leachate or groundwater quality associated with that
site. The reasons for this apparent lack of correlation include:
o Field leachate may have migrated from elsewhere and is
co-present with, but not indicative of, the chemical fill;
consequently, samples taken from the fill were not indicative of
that portion of the fill responsible for the field leachate.
o Leaching process used in the laboratory was not representative
of the field leaching environment.
o Chemical fill materials had lost the most soluble or readily
leached constituents and, hence, any further leaching could not
reproduce the field leachate composition.
The lack of correlation for this single case does not preclude use of
leaching tests for all other sites. These results do demonstrate the
need for careful site analysis during interpretation of laboratory data.
Landfill conditions that should be considered include age of waste,
amount of prior moisture infiltration, and initial waste composition.
For many existing landfills, some of this information cannot be
determined; and laboratory leaching of small samples taken from landfills
that are of unknown initial composition and have undergone unknown field
leaching seems unpromising as a means for predicting genuine field
leachate composition or potential threat to groundwater.
U °.. • .-;::-orr^?r*?>!
R, •.-'':-': V, f.Pjr, j
2iO South Dcv;»~o
Chicago, Illinois 60604
•:ncy
..;~;,
52
»U.S. Government Printing Office 1984 - 421-545/3101
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