United States
Environmental Protection
Agency
Research and Development
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
EPA/600/SR-93/167 October 1993
or EPA Project Summary
Evaluation of Solidification/
Stabilization Treatment
Processes for Municipal Waste
Combustion Residues
David S. Kosson, Teresa T. Kosson, and Hans van der Sloot
The investigations described in this
report were carried out to compare and
evaluate the effectiveness of solidifica-
tion/stabilization (S/S) processes as
treatment technologies for residues
from municipal waste combustion
(MWC). A full, factorial, experimental
design was used to evaluate five S/S
processes. The two experimental fac-
tors were the residue type to be treated
and the S/S process. The three experi-
mental levels within the residue type
factor were (1) bottom ash, (2) air pol-
lution control (APC) residue, and (3)
combined ash. The six experimental lev-
els within the S/S process factor were
the untreated residue, a Portland-ce-
ment-only control process, and four
selected vendor processes. Thus, 2 ex-
perimental factors at 3 and 6 experi-
mental levels, respectively, resulted in
the evaluation of 18 experimental cases.
Evaluation of each experimental case
included analysis of chemical compo-
sition, physical properties, durability,
and leaching characteristics. The test-
ing included moisture content, loss on
ignition, bulk density, modified Proctor
density, particle size distribution, per-
meability, specific surface area, po-
rosity, cone penetrometer, unconfined
compressive strength, pozzolanic ac-
tivity, unconfined compressive strength
after immersion, wet/dry, freeze/thaw,
toxicity characteristic leaching proce-
dure (TCLP), availability leach test
(ALT), distilled water leach test (DWLT),
acid neutralization capacity (ANC), and
the monolithic leach test (MLT).
Based on comparison of untreated
residues with treated residues, the S/S
processes evaluated generally did not
decrease the potential for the release
of target contaminants. A phosphate
process did, however, reduce the po-
tential for lead to be released. Whether
treated or not, the typical release po-
tential for metals was a small fraction
of the total metal concentration present
in the residues.
This Project Summary was developed
by EPA's Risk Reduction Engineering
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
The proper management of MWC resi-
dues is necessary to ensure that the use
of combustion as a solid waste manage-
ment method protects human health and
the environment. Although recent Federal
regulations for municipal solid waste
(MSW) and landfills (Federal Register, Oct.
9, 1991) address the disposal of MWC
residues, regulations specific to ash dis-
posal generally remain the responsibility
of individual states. Recently, the U.S.
Congress has considered legislation that
would require the U.S. Environmental Pro-
tection Agency (EPA) to develop compre-
hensive national ash disposal, treatment,
and utilization standards. To have the sci-
entific data available to support possible
future legislative requirements to promul-
gate technical guidance and/or regulations
Printed on Recycled Paper
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for the proper management of MWC resi-
dues, the EPA initiated studies on MWC
ash characteristics, ash disposal facilities,
and ash management practices. This study
adds to that database.
Specific Objectives and
Approach
The investigations described in this re-
port were carried out to compare and
evaluate the effectiveness of S/S pro-
cesses as treatment technologies for bot-
tom ash, APC residue, and combined ash.
Rather than determine how ash charac-
teristics are affected by municipal waste
combustor designs, operating conditions,
and waste input, the program emphasized
the evaluation of S/S treatment technolo-
gies. Therefore, the residues included in
the study were limited to those from a
single, modern, waste-to-energy facility.
The specific objectives of this study were
to:
1. define residue sampling, preparation,
and characterization protocols to
permit bench and pilot-scale
demonstrations of S/S treatment
processes with representative
residues;
2. carry out MWC residue S/S treatment
process demonstrations under
carefully controlled and monitored
conditions;
3. determine how the S/S treatment
process affects the fundamental
physical and chemical properties of
the MWC residues;
4. compare the effects of the S/S
processes on leaching properties of
MWC residues through laboratory
procedures, which include the TCLP
and other tests that can estimate
contaminant release potential and
release rate over a prolonged period
of time and under diverse
environmental conditions; and,
5. evaluate the physical durability of
the treated MWC residues during
aggressive environmental cycling
tests.
A full factorial design was used to evalu-
ate five S/S processes for treating MWC
residues. The two experimental factors
were the residue type to be treated and
the S/S process. Residue types tested
were (1) bottom ash, (2) APC residue,
and (3) combined ash. The six experi-
mental levels within the S/S process fac-
tors were the untreated residue, the Wa-
terways Experiment Station (WES) Con-
trol (Portland cement only) S/S process,
and four selected vendor S/S processes.
Thus, 18 experimental cases were evalu-
ated in triplicate.
The three residue types were obtained
during a single composite sampling taken
from a typical, state-of-the-art, mass-burn
municipal waste combustor. The facility
has a lime-slurry spray drier (wet-dry), an
acid gas scrubber, and a fabric filter par-
ticulate removal system. Bulk residue
samples were dried, size reduced,
screened, and homogenized before use
in this program. Thus all process demon-
strations, testing, and evaluations were
carried out on preprocessed residues to
facilitate laboratory-scale testing and the
comparisons of treatment effects.
Five S/S processes were evaluated.
Four of the processes were proprietary
modifications of four different generic S/S
processes. The four proprietary processes
evaluated were:
• Portland cement and polymeric
additives or other proprietary additives
(Process 1);
• Portland cement and soluble silicates
(Process 2);
• Cement kiln dust and proprietary
additives (Process 3);
• Addition of soluble phosphates
(Process 4).
The fifth process (WES) used Type 1
Portland cement only (control process).
The Type 1 Portland-cement-only process
was selected to provide a baseline com-
parison of the treatment effects of Port-
land cement without vendor additives.
All vendors demonstrated their specifi-
cally designed S/S processes on each
residue type. The vendors were provided
approximately 50 Ib of each residue type
to develop optimum formulas before the
process demonstrations. They were also
provided a list of test and program objec-
tives that would be used to evaluate each
process. The vendors were not provided
specific performance criteria to which the
residue should be treated; performance
criteria were left to the vendor's discre-
tion. Based on analysis of results, vendor
process optimization may have focused
on minimizing contaminant release based
on TCLP, concurrent with minimizing cost,
and not on maximizing the physical prop-
erties of the treated residue.
Demonstrations were conducted under
the observation of EPA representatives
and U.S. Army Corps of Engineers per-
sonnel. Each demonstration, done in trip-
licate, consisted of the vendor carrying
out the specified process to produce ap-
proximately 100 Ib of treated residue. Each
experimental case was analyzed for chemi-
cal composition and tested for physical
properties, physical durability, and leach-
ing characteristics with the use of the fol-
lowing tests: moisture content, loss on
ignition, bulk density, modified Proctor den-
sity, particle size distribution, permeability,
specific surface area and porosity, cone
penetrometer, unconfined compressive
strength, pozzolanic activity, unconfined
compressive strength after immersion, wet/
dry, freeze/thaw, TCLP, ALT, DWLT, ANC
test, and MLT.
Summary of Leaching Tests
The leaching tests were selected to pro-
vide a broad understanding of contami-
nant release under a variety of potential
environmental conditions. The primary ob-
jective was to evaluate fundamental leach-
ing properties rather than to simulate spe-
cific environmental exposure scenarios.
These fundamental leaching properties
were (1) release potential, (2) elemental
solubility as a function of pH, and (3)
release rate under diffusion-controlled con-
ditions. This approach permits the use of
leaching data to estimate contaminant re-
lease for a variety of environmental condi-
tions instead of only the particular expo-
sure scenario tested. TCLP also was car-
ried out on untreated and treated residues
for comparison purposes. Untreated resi-
due samples were tested after mechani-
cal processing steps, which included
screening, size reduction, and homogeni-
zation. Therefore, results from testing the
untreated residues may not be indicative
of the behavior of "as disposed" residues,
which have not been mechanically pro-
cessed. The leaching tests and the basis
for selecting each are discussed in the
following paragraphs.
The TCLP was selected to allow these
results to be compared with a broad data-
base of results from tests of other materi-
als. The TCLP was carried out in accor-
dance with the method outlined in the
U.S. Code of Federal Regulations, Title
40, Part 268, Appendix 1.1988. In this test,
a solid sample is crushed to a sample
size less than 9.5 mm and is extracted
with dilute acetic acid at a 20:1 liquid-to-
solid ratio. The extraction solution is either
buffered or unbuffered depending on the
alkalinity of the material to be tested. Only
a fixed quantity of acid is used for the
extraction, and therefore, the final pH of
the extract may vary widely. Thus, metals
concentrations observed in the extract of-
ten reflect the pH-dependent solubility con-
straints of the specific element. The con-
taminant concentrations in the test
leachate are compared with a published
list of limits that apply to hazardous wastes
(not MWC residues).
The ALT was selected to assess the
maximum amount of specific elements or
species that could be released under an
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assumed "worst case" environmental sce-
nario. This test, originally developed by
the Netherlands Energy Research Center,
is carried out on a sample size reduced to
less than 300 nm. Two serial extractions
are carried out, each at a 100:1 liquid-to-
solid ratio, with the use of distilled water.
The pH is controlled to pH 7 during the
first extraction and to pH 4 during the
second extraction by using an automatic
pH controller that delivers dilute nitric acid.
Thus, the final extraction pH is controlled
rather than the amount of acid used. The
first and second extracts are combined for
analysis. The very large liquid-to-solid ra-
tio ensures that the contaminant release
is not constrained by its solubility at the
final pH and that the amount of contami-
nant extracted is the maximum amount
that would be available at that pH. This
test generally extracts all species not tightly
bound in a mineral or glassy matrix. The
test does not provide information on the
rate of contaminant release.
The DWLT was selected to assess the
amount of specific elements or species
that might be released under continued
exposure to rainfall or to clean water per-
colation. Synthetic acid rain solutions were
not selected because the very high natu-
ral alkalinity of the residues would signifi-
cantly limit the effects of acid rain acidity.
The DWLT was carried out in accordance
with procedures of the sequential batch
leaching test used at the Environmental
Laboratory, U.S. Army Corps of Engineers.
A sample, crushed in size to less than 2.0
mm, is extracted four times in succession,
each at a 10:1 liquid-to-solid ratio with the
use of distilled water as the extractant.
Acid is not added nor is pH controlled.
Thus, the natural buffering capacity of the
material controls the final extract pH, which
was typically between pH 10 and 12 for
the materials tested. The first and second
extracts were combined for analysis, as
were the third and fourth extracts. Results
are used to estimate the amount of con-
taminant released over prolonged expo-
sure to the leachant and to provide limited
information on the rate of contaminant re-
lease.
The ANC test assesses the solubility of
specific metals over a broad pH range.
The test was carried out on a residue
sample crushed and size reduced to less
than 300 urn. Eleven separate extractions
are performed using separate samples at
a liquid-to-solid ratio of 5:1. The low liq-
uid-to-solid ratio results in the extraction
being solubility-constrained for some
analytes. Each extraction receives a dif-
ferent amount of dilute nitric acid, varying
from 0 to 12 meq/g dry residue, resulting
in a range of final pHs. A titration curve
also is obtained for each material tested.
The MLT was used to assess the re-
lease rate of specific elements and spe-
cies from the untreated and treated resi-
dues under diffusion controlled conditions.
This would be the case under field condi-
tions where the flow of infiltration or con-
tacting water is predominantly around
monolithic structures (e.g., blocks, other
forms, or low permeability, compacted fill).
The MLT was carried out based on a
modification of the American Nuclear So-
ciety (ANS), American National Standard
Measurement of the Leachability of Solidi-
fied Low-Level Radioactive Wastes by a
Short-Term Test Procedure (ANSI-
16.1,1986). A 4-cm diameter by 4-cm long
cylindrical, monolithic sample was tested
instead of the specified size test speci-
men. The monolithic samples were ex-
tracted by contacting them with 8.47 L
distilled water for up to 64 days. Contact-
ing water was replaced with fresh distilled
water at 1, 2, 4, 8, 16, 32, and 64 days
and analyzed for metals and other spe-
cies.
A new test method was developed for
evaluating compacted granular materials.
Release rate data were obtained for un-
treated bottom ash and combined ash by
compacting each ash at optimum mois-
ture content, using modified Proctor
compactive effort, in 4" diameter by 4"
long cylindrical polyethylene molds. Speci-
mens were cured in the mold for 28 days
at 24°C and 98% relative humidity. The
exposed face of the specimen in each
mold was covered with a 22-mm-thick layer
of 3-mm-diameter glass beads and con-
tacted with 8.47 L distilled water. Contact-
ing water was replaced with fresh distilled
water at 6 hr and at 1, 2, 4, 8, 16, and 32
days.
Modeling of the release data in con-
junction with the results of the availability
leach test was used to determine effective
diffusion coefficients, tortuosity, and chemi-
cal retention factors for estimating long-
term release rates for selected species.
The full report provides the results of each
of these determinations for each element
assayed and for each S/S process and
residue type evaluated.
Test Results
When the extracts from laboratory leach
tests are chemically analyzed, the con-
centration in the aqueous phase can be
determined. However, transforming the
concentration data into element or spe-
cies release (e.g., the mass of an element
or species emitted from the solid matrix
into the extract per unit mass of solid
extracted) permits normalization and the
comparison of data obtained from differ-
ent leach tests. The TCLP, DWLT, and
ALT are all intended to assess the poten-
tial for (or the maximum extent of) species
release under different extremes of leach-
ing conditions. Each test, however, em-
ploys different liquid-to-solid ratios and
extraction conditions. Only the TCLP has
a defined concentration basis for interpre-
tation of resulting extract concentrations.
Thus, data interpretation on an extract
concentration basis is of limited value.
Using additives for each treatment pro-
cess and varying treated residue moisture
contents may result in dilution effects, fur-
ther confounding direct comparison of ex-
tract concentration data. To provide more
uniform data interpretation from these
leaching tests, extract concentration data
were transformed to a basis of release
per mass of residue extracted. Results
are based on a comparison of treated
residues with the untreated results. The
typical release potential for metals was a
small fraction of the total metal concentra-
tion present in the residues. Detailed re-
sults for each element assayed for each
process and residue type are provided in
the full report.
The TCLP, DWLT, and the ALT leach-
ing data are interpreted on a release ba-
sis because these test results most fre-
quently are viewed as the potential for
release under the extreme conditions rep-
resented by the testing procedures. The
ANC test is the principal exception to
leaching data interpretation on a release
basis. The ANC test was performed at a
low liquid-to-solid ratio (5:1) to facilitate
determining pH titration curves and satu-
rated solution concentrations of a variety
of elements as a function of pH. There-
fore, it was most useful to present ANC
data on a concentration basis. In addition,
extract data also have been presented on
a concentration basis for cadmium, cop-
per, lead, and zinc from TCLP extractions.
Table 1 summarizes the levels of im-
mobilization achieved by each process for
each of the target elements in all three
residues, as obtained by the most aggres-
sive of all leaching procedures used, the
ALT. These levels ranged from total im-
mobilization of aluminum in APC residue
by Process 4 to no immobilization at all of
cadmium in the same residue by Pro-
cesses 1, 2, 3, and WES control. No one
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Table 1. Fractions of Elements Released in the Availability Leach Test after Treatment
A PC Residue
Aluminum
Cadmium
Calcium
Chloride
Copper
Lead
Sodium
Potassium
Zinc
Bottom Ash
Aluminum
Cadmium
Calcium
Chloride
Copper
Lead
Sodium
Potassium
Zinc
Combined Ash
Aluminum
Cadmium
Calcium
Chloride
Copper
Lead
Sodium
Potassium
Zinc
Total"
Concentration
(mg/kg ash)
25,586
137
290,725
90,325
515
2,969
20,467
15,598
17,453
51,749
35
1 13,087
24,301
1,477
1,563
19,777
9,510
6,793
56,083
32
123,357
28,922
1,734
1,054
21,678
13,245
6,172
Process
1
(%)
16
>100f
>100f
>100f
30
40
>100f
>100f
38
5
23
53
61
5
9
17
21
10
11
>100f
>wot
55
14
24
32
52
27
Process
2
(%)
31
>100f
95
>100f
55
72
>wot
>100f
62
10
29
>100f
>100f
18
10
>100f
48
>100f
27
63
>100f
>wot
23
47
>100f
57
21
Process
3
(%)
33
>100f
>100f
>100f
76
76
>100f
>100f
69
11
46
>100t
>100f
13
20
38
>100f
24
21
63
>100f
>100f
22
>100f
34
>100f
32
Process
4
(%)
1
87
85
>100f
25
0.1
94
>100f
38
1
49
78
71
15
3
17
24
27
1
81
85
>100f
14
4
24
36
35
WES
Control
(%)
>100f
>100f
>100f
>wot
>100f
>100t
>100f
9
51
92
>100f
10
21
23
47
31
9
75
>100f
>100f
19
32
24
43
34
* All total element concentrations are based on NAA results except lead, which is based on SW-846 results.
t Values nominally greater than 100% were calculated because of either contributions from process additives or correction for process dilution.
process demonstrated superiority over
other processes for all elements. Note,
however, that Process 4 retained lead in
all the treated residue types significantly
better than did the other processes.
Data from the other leaching tests, al-
though not given in this Project Summary,
are presented in detail in the full report.
No clear pattern could be noted other
than that no single process demonstrated
clear superiority over the other processes
for all target elements as was noted with
the ALT, except for lead in Process 4.
Another measure of immobilization used
in this study is the level of total dissolved
solids (IDS) released during the DWLT.
Data obtained from this test showed that
all processes were comparable to one an-
other with releases ranging from 4% to
32%. Significantly more TDS were re-
leased from the APC residue compared to
the other ash types. Many of the treat-
ments resulted in increased release of
TDS when compared to the untreated resi-
dues. Table 2 shows the releases from all
three residues by each of the processes
as well as the control and the untreated
samples.
Conclusions
Based on the results presented in the
full report of all the testing conducted on
the untreated and treated residues, the
key findings and conclusions are as fol-
lows:
• The S/S processes evaluated
generally did not decrease the
potential for release of target
contaminants based on comparison
of untreated residues with treated
residues. The phosphate process,
however, did reduce the potential for
lead to be released.
• Whether the MWC residues were
treated or not, the typical release
potential for metals (lead, cadmium,
zinc, etc.) was a small fraction of the
total concentration present in the
residues. Release rates of the
elements were very low for
compacted, granular, untreated
bottom ash and combined ash.
Release rates also were very low for
bottom ash and combined ash treated
by processes that produced physically
durable specimens.
The S/S processes evaluated did not
successfully treat the residues to
reduce the potential for release of
TDS and soluble salts. Whether the
MWC residues were treated or not,
the release potential and release rates
were high for TDS and the salts of
calcium, sodium, potassium, chloride,
and sulfate. The total amounts of
these constituents released typically
approached the total concentration in
the MWC residues. In the case of the
APC residues, the treatment
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Table 2. Comparison of Total Dissolved Solids Released for the Distilled Water Leach Test
(g release/kg ash, dry solid), and the Weight % of the Material Released *n parenthesis).
Sample source
Untreated
Process 1
Process 2
Process 3
Process 4
WES control
Bottom Ash
58 (6%)
53 (4%)
187 (12%)
126 (7%)
47 (4%)
59 (5%)
A PC Residue
289 (29%)
640 (32%)
565 (26%)
578 (24%)
194 (15%)
671 (30%)
processes increased the release
potential of the salts.
• The high concentration and ultimate
fate of soluble salts in MWC residues
should be carefully considered in the
design of treatment processes and
the use and disposal of the residues.
• Based on results from the program,
ARC residues have the least potential
for use in applications requiring
structurally durable products. The
physical retention values for the
treated ARC residues indicated limited
or no physical retention. The major
contaminant release from the ARC
residue was salts. In excess of 30%
of the total mass was released in the
form of sodium, calcium, chloride, arid
sulfate salts.
• The use of proprietary additives in
the evaluated S/S processes did not
enhance the strength of the treated
residues. The Portland-cement-only
(WES control) process produced test
specimens with unconfined
compressive strengths greater than
or equal to those of all the processes
with proprietary additives. It should
be noted, however, that high strength
probably was not an objective of the
vendor's processes. Process 4
developed a granular product.
• Evaluation of S/S process design,
performance, and treatment efficiency
should be based on a matrix of several
testing protocols. No single test, such
as TCLP, can provide all the
information required to evaluate
contaminant release potential,
contaminant release rate, and physical
durability. An appropriate test matrix
to evaluate S/S processes shoulc
include tests that will address these
factors.
Formulas for most processes
evaluated in this study were probably
developed on a limited number of
testing procedures. Variations in
Portland-cement-based and other
S/S technologies will influence the
Combined Ash
60 (6%)
54 (4%)
208 (13%)
144 (8%)
56 (5%)
79 (6%)
degree of durability and chemical
leaching potential. Therefore,
substantial improvements in S/S
process optimization may be
obtainable by optimizing process
design based on results of multiple
test criteria.
• The Portland-cement-based proc-
esses can be formulated to produce
S/S test specimens of MWC bottom
and combined residues with high
structural integrity and increased
resistance to weathering. These types
of processes, if properly designed,
are likely to be successful in producing
monolithic products with physical
properties acceptable for various uses.
This does not mean, however, that
the chemical characteristics would
also be acceptable. Physical durability
or possessing a monolithic structure
does not ensure acceptable
performance with respect to
contaminant release.
• The release rate of most potentially
toxic metals will be very slow to
negligible for S/S-treated MWC
residues, at least those that have
minimal leachability in the raw state.
• The unconsolidated, granular nature
of the ash material required that a
method for estimating diffusion-
controlled release from compacted
granular materials be developed. Such
a method was developed for this
evaluation, and the application of a
modified MLT to determine intrinsic
leaching properties for granular
materials has proven very consistent.
The data are comparable with results
from other types of diffusion
measurements. The tortuosity data
obtained in the experimental setup
are consistent with diffusion
measurements using radiotracers.
TCLP was not a good indicator of
release from untreated and treated
residues for several reasons. Variable
end-point pH for the extraction
resulted in wide variation in estimated
metals release because of pH-
dependent solubility constraints. The
low liquid-to-solid ratio for the TCLP
(20:1) also may have resulted in
solubility limitations for many elements
of concern. Finally, TCLP does not
provide for determination of the total
release of soluble salts and anions.
• The most durable test specimens to
the cyclic weathering tests and the
immersion tests were those with the
highest unconfined compression
strength (UCS). Thus, UCS may be
useful as a preliminary indicator of
physical durability.
• The MLT for construction materials
and stabilized products provides
intrinsic information on long-term
leaching effects and usefulness in
relation to product quality. The MLT
also provides useful information for
improving product quality. By focusing
on the controlling parameter requiring
adjustment, initial estimates of release
rates and fluxes for varied application
scenarios can be obtained. The
distinction between physical retention
and chemical retention and the
release mechanisms (dissolution,
wash-off, and diffusion) can be made.'
Existing regulatory tests do not
provide such useful information.
• Physical retention was directly
correlated with the compacted, dry
densities of the material for the bottom
and combined ashes. The test
specimens with the greater densities
had more physical retention.
• The EPA-recommended methods of
chemical analysis (SW-846) were not
comparable in many cases to the
neutron activation chemical analysis
(NAA) for total elemental
concentrations in the raw and treated
residues. The EPA method results
indicated significantly lower elemental
concentrations than did the NAA
methods; this suggests that only
partial analytical recoveries occurred.
This discrepancy warrants further-
investigation into the chemical
analysis methods to investigate and
develop more applicable methods for
similar type solid matrices.
The full report was submitted in partial
fulfillment of CR 818178-01-0 by Rutgers
The State University of New Jersey CR
813198-01-0 by the New Jersey Institute
of Technology and an interagency agree-
ment between the U.S. Environmental Pro-
tection Agency and the U.S. Army Corps
of Engineers, Waterways Experiment Sta-
tion, under the sponsorship of the U S
Environmental Protection Agency
GOVERNMENT PRINTING OFFICE: W3 - 750-07I/JJOW3
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David S. Kosson is with Rutgers, The State University of New Jersey,
Piscataway, NJ 08855; Teresa T. Kosson is with the U.S. Army Corps of
Engineers, Vicksburg, MS 39180; and Hans van der Sloot is with the
Netherlands Energy Research Foundation (ECN), Petten, The Netherlands
1755ZG.
Car/ton Wiles is the EPA Project Officer (see below).
The complete report, entitled "Evaluation of Solidification/Stabilization Treat-
ment Processes for Municipal Waste Combustion Residues," (Order No.
PB93-229 870/AS; Cost: $61.00, 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:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agetncy
Cincinnati, OH 45268
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-93/167
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