United States
Environmental Protection
Agency
Municipal Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-84-022 Mar. 1984
vvEPA Project Summary
Evaluation of the RCRA
Extraction Procedure: Lysimeter
Studies with Municipal/Industrial
Wastes
Jt
A study was initiated to determine the
accuracy with which the U.S. Environ-
mental Protection Agency (EPA) extrac-
tion procedure (EP) simulates the
leaching of an industrial waste when
codisposed with municipal refuse in a
nonsecure landfill. The EP is used in the
regulations promulgated under the
Resource Conservation and Recovery
Act.
Simulated codisposal of industrial
and municipal waste was initiated
October 28, 1980. Cylindrical test
cells 0.91 x 1.8 m were designed to
simulate sanitary landfill environments.
The five types of industrial wastes
tested were oil reclaiming clay, petrole-
um refinery incinerator ash, paint
manufacturing sludge, solvent refining
sludge, and tannery waste. Fifteen test
cells were loaded to provide triplicate
samples of each industrial waste leach-
ate. Each week, all cells received an
8.4-liter addition of deionized water,
the equivalent of 1.27 cm of infiltrated
rainfall. Leachate samples were collected
from beneath the municipal waste and
the municipal/industrial wastes each
month. Seven inorganic parameters
were measured during five sample
periods for leachate collected below
both wastes.
The metal concentration from the
leachate collected below the municipal/
industrial waste was compared with
that produced in the EP extract. When
the EP extract concentration of a
specific metal exceeded the concentra-
tion criteria (100 times the National
Interim Primary Drinking Water Stan-
dards), the test cells also showed a
concentration that exceeded the criteria.
But EP concentrations were generally
lower than those for the same wastes in
the test cells, and very little quantitative
relation was shown between the EP and
the test cell results.
This Project Summary was developed
by EPA's Municipal Environmental
Research Laboratory. Cincinnati, OH.
to announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
Under the Resource Conservation and
Recovery Act of 1976 (RCRA), the U.S.
Environmental Protection Agency (EPA)
was charged with promulgating regulations
identifying hazardous waste characteris-
tics and listing particular hazardous
wastes. To determine whether a waste is
hazardous, two mechanisms may be
used: (1) identification by source or
chemical name as a waste that is
hazardous in all waste management
scenarios (usually those wastes histori-
cally associated with hazard), and (2)
description of properties that could result
in harm to either human health or the
environment. Such properties include the
following:
1. Ignitability
2. Corrosivity
3. Reactivity
4. Toxicity of extraction procedure
extract
5. Radioactivity
6. Infectiousness
7. Phytotoxicity
8. Teratogenicity and mutagenicity
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To date, EPA has mainly relied on the first
four characteristics because no validated
test protocols exist for the others and
because many radioactive wastes are
separately regulated.
This study deals with the characteristic
of EP extract toxicity. The characteristic
was developed by EPA to identify those
wastes that pose a threat to groundwater
if placed in an unsecure landfill, especially
those admixed with municipal solid
waste. The EP measures the potential of
waste constituents for migrating out of a
landfill and contaminating the groundwa-
ter under poor management conditions.
The procedure was designed to simulate
the leaching action of the acidic leachate
generated in municipal landfills. As
published in the regulations, the EP
involves the dilute acetic acid extraction
of a waste sample at a specified pH and
with constant agitation over a 24-hr
period. The mixture is then filtered, and
the resulting extract is analyzed. Currently,
the extract is analyzed for eight heavy
metals (Ag, As, Ba, Cd, Cr, Se, Hg, and Pb)
and six organic compounds included on
the list of National Interim Primary
Drinking Water Standards (NIPDWS).
Wastes generating an EP extract contain-
ing more than 100 times the limits
established for the NIPDWS are hazardous.
The factor of 100 provides for dilution and
attenuation of the contaminants as they
migrate to the point of water use.
Though EPA has expended considerable
effort in developing and selecting the EP,
no consensus exists as to its validity.
Concern has been voiced that it does not
address some significant factors in
leachate generation, including redox
potential, buffer capacity, complexation
capacity, ionic strength, surface area, and
contact time. The primary objective of this
study was to determine how accurately
the EP mimics landfill leaching of
industrial waste. This objective was to be
achieved by comparing potentially toxic
constituents in the EP extract from the
industrial wastes with those in the test
cell leachates after contact with the
industrial wastes. This comparison of the
EP extract should duplicate the highest
concentrations in the leachates from the
test cells.
A secondary objective of this study was
to obtain data on the landfill teachability
of selected organic compounds in some of
the industrial wastes. This objective was to
be achieved by selectively analyzing
various leachate samples collected
before and after contact with the industrial
wastes. The goal was to develop a test that
better simulates the natural leaching of
potentially toxic organics in a landfill
environment.
Methods and Procedures
Simulated codiposal of industrial and
municipal waste began on October 28,
1980. Cylindrical test cells 0.91 x 1.8 m
were designed to simulate sanitary
landfill environments. The five represen-
tative industrial wastes selected for study
were oil reclaiming clay, petroleum
refinery incinerator ash, paint manufac-
turing sludge, solvent refining sludge,
and tannery waste.
industrial Wastes
All industrial wastes were acquired
from a commercial waste disposal
facility. A 208-liter drum of each of the
five wastes was obtained, and bulk
analyses were performed on the contents
in duplicate to establish baseline data.
Samples of the industrial wastes were
subjected to the EP as described in the
Code of Federal Regulations (40 CRF, Part
261, Appendix II). All EP tests were
conducted in triplicate.
Municipal Wastes
Municipal wastes were gathered from
waste collection routes in Vicksburg,
Mississippi. Routes were screened to
include only those containing residences
and small businesses exclusively. Some
8.5 metric tons of waste were collected
from the curbside and delivered to the
laboratory within 2 hours.
Test Cells
Test cells were designed to contain
industrial and municipal wastes in a
simulated landfill situation. Five percent
industrial waste (by weight) and 95
percent municipal waste were used in the
test cells to simulate actual emplacement
ratios and codiposal operations. The
industrial wastes were placed so that
they were in direct contact with the
overlying municipal waste. The munici-
pal waste was compacted to a density of
about 475 kg/m3. Leachate samples
were collected from both above and
below the industrial waste layer. The
sample collected above was representative
of the leachate generated in the municipal
wastes, and the sample collected below
was representative of the municipal waste
leachate after it had been in contact with
the industrial waste.
Fifteen cylindrical test cells (0.91 x 1.8
m) were loaded to provide triplicate
samples of each industrial waste leachate.
A cross section of a completed test cell
appears in Figure 1. As soon as all test
cells were loaded, each received 8.4 liters
of deionized water (the equivalent of 1.27
cm of infiltrated rainfall). Thereafter, each
cell received 8.4 liters of deionized water
every 7th day until completion of the
study. Field saturation of all test cells was
reached after 137 days. An additional 54
days elapsed before enough leachate
accumulated in the municipal waste
leachate collectors for analysis.
Leachate samples for analysis were
collected from the test cells during five
sampling periods from May 6 to October
21, 1981.
Analytical Techniques
Methods of analysis and lowest report-
ing concentrations for parameters reported
are summarized in Table 1. The same
methods of analysis were used for the
bulk analysis, EP extracts, and leachates.
A quality assurance program was estab-
lished to ensure the reliability and
comparability of the analytical data.
National Bureau of Standards and EPA
standard reference samples were used
to verify all analytical techniques.
, 91.0cm ,
Municipal Waste
Leachate Samp/ing
Figure 1. Exterior view of test cell showing
positions of leachate sample
collect/on ports.
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Table 1. Methods of Analysis
Parameter
As
Ba
Cd
Cr
Hg
Pb
PH
Toluene
Xylene
Cresols
Procedures and/or Instrumentation
Determined with a Perkin-Elmer* Atomic Absorption
Unit with Hydride System
Determined with a Spectrametrics Argon Plasma
Emission Spectrophotometer Model II
Determined with a Perkin-Elmer Heated Graphite
Atomizer Atomic Absorption Unit
Determined with a Perkin-Elmer Heated Graphite
Atomizer Atomic Absorption Unit
Determined by standard cold vapor technique on
Perkin-Elmer Atomic Absorption Unit
Determined with a Perkin-Elmer Heated Graphite
Atomizer Atomic Absorption Unit
Electrometric
Determined using purge and trap (Tenak) method
and a HP gas chromatograph
Determined using purge and trap (Tenak) method
and a HP gas chromatograph
Determined using Base Neutral Acidic Extraction
procedure and a HP gas chromatograph
Lowest Reporting
Concentration in
Aqueous Solution
(ppm)
0.01
0.01
0.0001
0.001
0.0002
0.001
—
0.1
0.1
0.1
* Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
EPA procedures for priority pollutants. Federal Register, 3 Dec., 1979.
Results and Conclusions
This study highlighted several problems
involved in the performance and interpre-
tation of the EP testing. Industrial wastes
containing significant amounts of oil or
other immiscible components may not
mix completely and may thus prevent
intimate contact between the waste
solids and the EP leaching solution. This
lack of contact could limit the transfer of
contaminants from the solids to the
leaching solution. This problem was
evident for the paint manufacturing
sludge.
The metal concentrations in the EP
extracts of the wastes studied were
generally low. In fact, many concentrations
were below the detection limit of the
analytical methods 'used. Only two
wastes had metal concentrations in the
EP extracts above the maximum allowable
concentrations and thus displayed EP
extract toxicity—the petroleum refining
incinerator ash and the paint manufac-
turing sludge.
Concentrations of As, Hg, and Se in test
cell leachates were generally below
detection limits. Other metal concentra-
tions varied, depending on the industrial
waste contained in the test cells. Metals
found at significant levels in the industrial
waste leachates tended to decrease in
concentration over the sampling periods.
Only four of the five industrial wastes
yielded test cell leachates with metal
concentrations above 10 percent of the
EP extract toxicity threshold: The solvent
refining sludge leached no metals at this
level, the paint manufacturing sludge
leached Cd, Cr, Hg, and Pb, the oil
reclaiming clay leached Cr and Pb, and
the petroleum refining incinerator ash
and the tannery sludge leached Cr.
Only two wastes had metal concentra-
tions in the test cell leachates above the
EP thresholds—the petroleum refining in-
cinerator ash (with an average Cr concen
tration of 136 mg/l) and the paint manufac-
turing sludge (with an average lead
concentration of 604 mg/l).
When metal levels in the industrial
waste test cell leachates were higher
than 10 percent of the EP thresholds, they
were generally much higher than those
in the EP extracts (65 to 2000 times
higher). The only exceptions were the Cr
levels associated with tannery sludge and
with petroleum refining incinerator ash,
in which the respective concentrations
were more nearly comparable.
Metals found at levels above the EP
thresholds in test cell leachates (Cr from
the petroleum refining incinerator ash
and Pb from the paint manufacturing
sludge) were also above the thresholds in
the EP extracts. The EP thus made a correct
qualitative prediction of the two industrial
wastes in this study that would present a
potential hazard by releasing metal
contaminants at concentrations greater
than 100 times the primary drinking
waste standards.
Limited organic analyses for toluene,
xylene, and cresol in the municipal and
industrial waste leachates showed that
their concentrations were very similar in
the leachates collected both before and
after contact with the industrial wastes.
Evidently the toluene, xylene, and cresol
(which were absent in the municipal solid
waste) migrated by diffusion as vapor
from the industrial waste into the overly-
ing municipal waste and were absorbed
by the leachate. As a result, no net
contribution of these organic contaminants
from the industrial wastes could be
quantified. But the organics concentra-
tions in the leachates from three of
the industrial wastes were sufficiently
high to pose a potential environmental
hazard should they migrate into ground-
water at a disposal site.
During the study, the municipal waste
leachate samplers in the test cells did not
collect enough leachate for analysis. This
problem appears to have been caused by
plugging of the samplers with partially
deteriorated epoxy paint and biological
growth and by diversion of the leachate
flow with large pieces of refuse (primarily
paper) above and around the sampler.
Though the EP made a correct qualitative
prediction of the two industrial wastes
studied that released metals at levels
exceeding the EP criteria, the EP in
general grossly underestimated the
highest concentrations found in the
industrial waste test cell leachates. Very
little quantitative relation exists between
the EP and test cell results.
Recommendations
Correlations between EP and test cell
results should be expanded to include
industrial wastes other than the five
tested so that a broader data base can be
developed.
Because of the problems encountered
in collecting municipal waste leachate,
the test cells should be modified if they
are to be used in further studies. Changes
should include replacing the perforated
metal plates in the samplers to eliminate
the need for the epoxy paint and shredding
of the municipal waste to eliminate large
pieces of refuse that could divert leachate
flow. More extensive changes would be
needed to eliminate the problems associ-
ated with migration of volatile organic
contaminants.
The full report was submitted in
fulfillment of Interagency Agreement
IAG-AD-F-1-347 by U.S. Army Engineer
Waterways Experiment Station under the
sponsorship of the U.S. Environmental
Protection Agency.
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This Project Summary was prepared by staff of the U.S. Army Engineer
Waterways Experiment Station. Vicksburg, MS 39180.
Robert E. Landreth is the EPA Project Officer (see below).
The complete report, entitled "Evaluation of the RCRA Extraction Procedure -
Lysimeter Studies with Municipal/Industrial Wastes," (Order No. PB 84-143
114; Cost: $8.50, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati. OH 45268
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