TECHNICAL BACKGROUND DOCUMENT
AND
RESPONSE TO COMMENTS
Resource Conservation and Recovery Act
Subtitle C - Hazardous Waste Management System
Section 3001
Identification and Listing of Hazardous Waste
Method 1311
Toxicity Characteristic Leaching Procedure
(TCLP)
U.S. Environmental Protection Agency
Office of Solid Waste
April 1989
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50272-101
REPORT DOCUMENTATION 1 1. REPORT NO. 1 2.
PAGE I EPfi/530—SW-90-0B0 1
| |
3, '
PB91-.tfl205 3
4, Title and Subtitle
TECHNICAL BACKGROUND DOCUMENT AND RESPONSE TO COMMENTS: RCRA SUBTITLE C
HAZARDOUS WASTE MANAGEMENT SYSTEM; SECTION 3001 - IDENTIFICATION ?! LISTING
OF HW; AND METHOD 1311 TOXICITY CHARACTERISTIC LEACHING PROCEDURE
5. Report Date
APRIL 19B9
b.
7. Author(s)
OSW
8. Performing Organization Rept. No
9. Performing Organisation Name and Address
U.S. EPA
Office of Solid Waste
401 M. Street SW
Washington, DC 20460
10. Project/Task/Work Unit No.
11. Contract(C) or Grant(G) No.
(0
(G)
12. Sponsoring Organisation Name and Address
13. Type of Report & Period Covered
BACK. DOCUMENT - 4/09
14.
15, Supplementary Notes
it. Abstract (Limit: 200 words)
The Agency received a total of 150 comments on the TCLP from 118 respondents. This document includes the response
to commenters as well as serves as the background document.
17. Document Analysis a. Descriptors
b. Iden t i f i ers/Op en-En ded Terms
c. C0SATI Field/Group
18. Availability Statement
RELEASE UNLIMITED
(See ANSI-Z39.1B)
19. Security Class (This Report)
UNCLASSIFIED
20. Security Class (This Page)
UNCLASSIFIED
21. No. of Pages
0
22. Price
OPTIONAL FORM 272 (4-77)
(formerly NTIS-35!
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TABLE OF CONTENTS
SECTION PAGE
Introduction 1
I. General Comments 8
A. Relationship to EP 8
II. Research Supporting Leaching Procedure Development 9
A. General Comments 10
B. Oak Ridge National Laboratory Testing: Phase I 11
C. Oak Ridge National Laboratory Testing: Phase II 14
D. Statistical Treatment of Data 15
III. Research Supporting the Leaching Procedure Development:
Ruggedness and Precision Evaluation 18
A. Collaborative Evaluation 18
B. Ruggedness Evaluation 21
C. Precision Evaluation 21
IV. General Leaching Procedure Issues 25
A. Accuracy of the TCLP 25
B. Treatment of Highly and Moderately Alkaline Wastes 26
C. Pre-screen Test 28
V. Specific Technical Comments on the TCLP as Proposed June 13f 1986 31
A. Extraction Vessels (ZHE) 31
B. Agitation Apparatus 36
C. Filters 37
D. Reagents 40
E. Leaching Media and Liquid/Solid Ratio 41
F. Particle Size Reduction *46
G. Procedure when Non-VolatHes are Involved .......48
H. Procedure when Volatlles are Involved 61
I. Quality Assurance Requirements 68
J. Multiple Extraction Procedure (MEP) and Oily Waste Extraction
Procedure (OWEP) .70
K. Other Technical Comments 71
VI. Comments on May 24, 1988, Proposed Modifications 73
VII. Analytical Constraints 82
A. Use of Quantitation Limits 82
B. Analytical Methods - General 87
C. SW-846 Method 8270 89
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VIII. Changes to the TCLP 93
A. EPA Changes Made Prior to Review of Public Comments 93
B. Changes Resulting from Comments on June 13, 1986, FRN 95
C. Changes Proposed in May 24, 1988, FRN 98
IX. References 99
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TABLES
Number Page
1. Commenters on TCLP as Proposed January 14, 1986, and June 13, 1986 3
2. Commenters on the May 24, 1988, Proposed Modifications 7
3. Results of TCLP Collaborative Studies Mean (Median) % Relative Standard
Deviation 23
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Introduction
On June 13, 1986, the USEPA proposed to amend Its hazardous waste
identification regulations under Subtitle C of the Resource Conservation and
Recovery Act (RCRA) by expanding the Toxicity Characteristic (TC) to include
additional contaminants (51 FR 21648). The agency proposed using a leaching
test, the Toxicity Characteristic Leaching Procedure (TCLP), to determine if
wastes should be classified as hazardous. Also, on July 9, 1986, (51 FR 24856)
and September 19, 1986, (51 FR 33297) the Agency noted the availability of
several other reports and studies containing additional data and information
supporting use of the TCLP. The TCLP was promulgated on November 7, 1986, as
part of the Land Disposal Restrictions Rule for Solvents and D1ox1ns (51 FR
40643-40652) and will be Incorporated in the manual "Test Methods for Evaluating
Solid Wastes: Physical/Chemical Methods" (SW-846) as Method 1311. In response
to these Federal Register notices, the Agency has received a substantial number
of comments from the American public. This document summarizes and responds to
those comments which addressed the use of the TCLP in the Toxicity
Characteristic Expansion rule.
The Agency received a total of 140 comments on the TCLP from 118
respondents. Twenty-two commenters addressed the TCLP as 1t was proposed in the
January 14, 1986, Federal Register notice on the Land Disposal Restrictions
rule, and eight of these later submitted comments on the June 13, 1986, Toxicity
Characteristic proposal as well. Five organizations made presentations at the
July 14, 1986, public hearing which addressed the proposed test, and three of
these also submitted written comments. Seventy-five additional individuals or
organizations submitted written comments on the TCLP as presented 1n the June-
13, 1986, proposal. These commenters Include 27 trade associations, 14
municipal sewer authorities, 44 other industries, 10 state or federal agencies
(Including Environment Canada), 9 hazardous waste management organizations, 4
consultants, 5 commercial laboratories, 3 Individuals, and two public interest
groups (the Environmental Defense Fund and the Natural Resources Defense
Council). Twenty-seven additional comments were received after the August 12
deadline for comment submittal. These were reviewed and are Included 1n this
background document. The specific respondents are listed in Table 1.
1
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On May 24, 1988, the EPA published proposed modifications to the TCLP
(Method 1311) in the Federal Register (53 FR 18792-18798). The proposed changes
included the use of a stainless steel cage in the bottle extractor, the addition
of new equipment suppliers, and a revised method flowchart. The Agency received
22 comments on the proposed changes. These comments were reviewed and summaries
and responses are included in Section VI of this Background Document. The
specific respondents are listed 1n Table 2.
Each of the major issues regarding the TCLP 1s discussed in a separate
section of this document. The issues are organized in a manner similar to that
of the preamble to the June 13, 1986, Federal Register proposal with general
issues addressed first, followed by comments on EPA's research relating to the
development and evaluation of the leaching procedure, and then specific aspects
of the extraction procedure and subsequent chemical analyses.
2
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TABLE 1. COMMENTERS ON TCLP AS PROPOSED
JANUARY 14, 1986, AND JUNE 13, 1986
Name of Comnenter
LogNumber(s) of Comment(s)
CONSULTANTS;
Battelle Pacific
Environmental Management and Engineering Inc.
Resource Consultants
University of Idaho
Total: 4
ELECTRIC UTILITIES:
Detroit Edison
TVA
Total: 2
INDIVIDUALS:
Brian B. Looney
Cate Jenkins
F. Winter and K. Farrell
TC0059
TC0008
TC0048
TC0011
T CO111
TCL017
TC0047
LDR024
TCQ113
Total: 3
INDUSTRIES:
American Motors
American Water Works Service Co.
Atchison, Topeka and Sante Fe Railroad
Briggs and Stratton
Chrysler
Eastman Kodak Co.
Finnegan Mat
Ford Motor Co.
General Battery Corp.
General Electric Co.
General Motors Corporation
HDR
Heil Quaker Corp.
ITT Rayonier Inc.
Union Camp
Total: 15
TCL055
TC0087
TCL042
TCL005
TC0039
TC0080
TC0102
LDR006, TC0135
TC0037
TCL026
TC0097
TC0137, TCL007
TC0010
TC0112
TC0093
continued
3
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TABLE 1. Continued
Name of Commenter LogNumber(s) of Comment(s)
LABORATORIES:
Burmah Technical Services
Compuchem Laboratories
Enwright Laboratories
Lancy Environmental Services
Deuel and Zahray Laboratories
Total: 5
MINING/METALS PROCESSING:
Al coa
Amax
Asarco, Inc.
Auburn Foundry Inc.
Chemetco
J. R. Simplot Co.
Kaiser Aluminum
Reynolds Aluminum
Total: 8
MUNICIPAL SEWER AUTHORITIES:
Cincinnati MSD
City of Colorado Springs
City of Indianapolis
City of Memphis
City of New York DEP
East Bay Municipal Utility Oistrict
Hennepin Dept. of Environment and Energy
LA County Sanitation Oist.
Metro Denver Sewage Disp. Dist.
Metro Seattle
Metropolitan Waste Control Commission of St. Paul
MSD of Greater Chicago
Narragansett Bay Commission
Northeast Ohio Regional Sewer District
Total: 14
continued
PH0010
TC0045
TC0063
TC0099
TCL113
LDR016, PH0012
LDR023, TC0140
TC0098
TC0006
TC0054
LDR013
TCQ119
TC0090
TC0096
TC0003
TC0041, TC0051
TC0131
TC0107
TCL016
TC0070
TC0128
TC0139
TC0130
TC0120
LDR003, TCL008
TC0094
TC0089
4
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TABLE 1. Continued
Name of Commenter LogNumber(s) of Comment(s)
PETROLEUM/CHEMICAL COMPANIES:
Air Products and Chemicals Inc.
American Cyanamid Company
Amoco Corporation
Chevron
Colorado Interstate Gas Co.
Conoco
Diamond Shamrock
DOW Chemical
El Paso Natural Gas
Kaiser Chemicals
Lubrizol Corporation
Mobil Oil Corp.
Questar Corp.
Shell- Oil Company
Standard Oil Company
Syntex Agribusiness Inc.
Texaco
Unocal Corp.
Vulcan Chemicals
TC0117, TCL092
TC0035
TC0058
TC0060, TCL077
TC0091
TC0116, TCL066
LDR010, TCL013
LDR021, TC0057, TCL088
TC0052
TC0108
TC0088
LDR027
TC0101
TC0073
TC0056
LDR017
LDR014
TCL082
TC0138
Total: 19
PUBLIC INTEREST GROUPS:
Environmental Defense Fund
Natural Resources Defense Council
TC0076
TCL112
Total: 2
GOVERNMENT AGENCIES:
Commonwealth of Virginia
Department of Energy
Environment Canada
Maryland Waste Mgt. Admin.
Minnesota Pollution Control Agency
NEIC
New Hampshire DPHS
New Jersey Dept. of Environmental Protection
NY State Dept. of Environmental Conservation
Texas Water Commission
TC0067
TCL019
TC0005
TC0127
TC0126
TC0071
TC0103
TC0007
TC0066
TC0053
Total: 10
5
continued
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TABLE 1. Continued
Name of Commenter LogNumber(s) of Comment(s)
TRADE ASSOCIATIONS:
American Mining Congress
American Petroleum Institute
Association of Metropolitan Sewerage Agencies
Assoc. of State and Territorial Solid Waste Mgt. Officials
Association of American Railroads
Can Manufacturers Institute
Chemical Manufacturers Association LDR031,
Government Refuse Collection and Disposal Assoc.
Halogenated Solvents Industry Alliance
Hazardous Waste Treatment Council
Institute of Scrap Iron and Steel, Inc.
International Fabricare Institute
Interstate Natural Gas Association of America
Leather Industries Research Lab
Michigan Chamber of Commerce
Michigan Manufacturers Association
National Council of the Paper Industry
for Air & Stream Improvements
National Electrical Manufacturers Assoc.
National Lime Association
National Paint and Coatings Assoc.
Pharmaceutical Manufacturers Assoc.
Porcelain Enamel Institute, Inc.
Rocky Mountain Oil and Gas Association, Inc.
Society of the Plastics Industry
Specialty Steel Industry of the US
Synthetic Organic Chemical Manufacturers Assoc.
Utility Solid Waste Activities Group
LDR012,
TC0043,
TC0002,
LDR030,
LDR001,
LDR025, TC0077,
LDR004,
LDR005
TC0118
PH0003
LDR020
TC0074
LDR009
TC0081
TC0030
TC0083
PH0001
TC0105
TC0106
TC0124
TC0024
TC0123
TC0064
TC0123
TCL060
LDR011
TCL025
TCL084
TC0044
TC0129
TCL095
TC0078
TCL049
TC0072
Total: 27
WASTE MANAGEMENT COMPANIES:
Browning-Ferris Industries
Cecos International
Chem Met Services
Chemical Waste Management, Inc.
Envirite Corporation
Envirosafe Services, Inc.
Penberthy Electromat Company
Waste Management Inc.
Wayne Disposal, Inc.
Total: 9
TC0065
TC0079
TCL023
TC0062, TCL036
TC0125
TC0095
PH0008
LDR028
TC0022
Grand Total: 118 commenters
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TABLE 2. COMMENTERS ON MAY 24, 1988 PROPOSED MODIFICATIONS
Name of Commenter
LogNumber(s) of Comment(s)
PETROLEUM/CHEMICAL COMPANIES:
Conoco, Inc.
Eastman Kodak
Lubrizol Corporation
Monsanto Company
Vulcan Material Company
LABORATORY:
Analytical Testing and Consulting Services
MINING/METALS PROCESSING:
Aluminum Company of America
ASARCO, Inc.
Chemetco
TRADE ASSOCIATIONS:
Association of American Railroads
Chemical Manufacturers Association
Institute of Chemical Waste Management
Institute of Scrap Recycling Industries, Inc.
Lead Industries Association, Inc.
National Council of the Paper Industry for
Air and Stream Improvements, Inc.
Secondary Lead Smelters Association
Steel Structures Painting Council
Society of the Plastics Industry
Steel Bar Mills Association
Utility Solid Waste Activities Group
ELECTRIC UTILITIES:
Pacific Gas and Electric Company
WASTE MANAGEMENT COMPANIES:
Chemfix Technologies, Inc. - *
TCA00010
TCAL0002
TCA00011
TCA00009
TCA00018
TCA00006
TCA00001
TCA00005
TCA00021
TCA00007
TCA00016
TCA00017
TCA00019
TCAL0001
TCA00003
TCA00015
TCA00004
TCA00014
TCA00008
TCA00013
TCA00020
TCA00002
TOTAL: 22 Commenters
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I. General Comments
A. • Relationship to EP
Thirty-three respondents expressed opinions on the relative merits of the EP
and TCLP tests and were almost evenly divided on the subject. Eighteen comments
asserted that the TCLP is an improvement over the EP, while fifteen stated that
the new test provides no advantage or that the EP should be retained.
One comment favoring the TCLP asserted that the proposed test represents a
substantial improvement over the EP toxicity test, while another stated that any
improvement over the current EP test is welcome. Most comments were more
qualified in their support. One claimed that the current extraction procedure
(EP) is inadequate, and that while the proposed TCLP may represent some degree
of improvement over the EP, there are still serious doubts about its validity
and replicability. Other comments expressed similar opinions.
Nine comments asserted that the TCLP provides no advantage over the current
EP and that, even though the current EP test has some serious weaknesses, there
is little evidence that the TCLP is an adequate substitute. Six comments stated
that the EP should be retained, at least for metals and non-volatile organics.
As discussed 1n the preamble, the Agency believes that the TCLP is needed in
order to permit the expansion of the Toxicity Characteristic to include volatile
organics, and also represents an improvement over the EP. Previous experience
showed that the recovery of volatiles with EP equipment was poor (S-Cubed,
1986c) and thus the EP is unsuitable for estimating the leaching potential of
volatile chemicals. The TCLP procedure is also simpler to perform than the EP
for metals and semi-volatile organics. Operational simplifications include
eliminating the requirement for continuous pH adjustment and replacing the 0.45
micron membrane filter with the 0.6 - 0.8 micron glass fiber filter to aid
liquid/solid separation. Specifying only one acceptable means of agitating the
samples also removes a source of variability in the test. (USEPA, 1986a)
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II. Research Supporting Leaching Procedure Development
Background
The Agency's research which led to the development of the proposed TCLP
consisted of three phases. The first phase was designed to narrow the range of
possible leaching procedures, and the second phase consisted of more extensive
evaluation of a smaller selection of tests. This resulted in choosing one
procedure as the draft TCLP. The third phase involved precision and ruggedness
evaluation of the selected method. Phases I and II are discussed in this
section of the background document while Phase III 1s addressed 1n the following
section.
In designing the research program, the Agency used the same model and
assumptions used 1n developing the EP test; namely, co-disposal of industrial
waste with municipal waste in a sanitary landfill. In conducting the tests for
the Agency, the U.S. Department of Energy's Oak Ridge National Laboratory (ORNL)
began Phase I with field lysimeters which were filled with domestic and
commercial refuse. This was done in order to generate a municipal waste
leachate which would be representative of the mismanagement scenario. The
generated leachate was used to extract four industrial sol id-wastes in pilot
scale leaching columns, and the concentrations of various organic and inorganic
parameters 1n the leachate were measured over time. (Francis et al., 1984)
Next, target concentrations were developed for each constituent of interest.
These concentrations were based on data from the pilot columns and were compared
with the results of a variety of laboratory leaching procedures. The lab tests
which were evaluated Included both batch and column procedures using four
leaching media and four media-to-waste ratios, in addition to the existing EP
test and a sequential batch leaching procedure. The two laboratory procedures
which most closely represented the results of the pilot scale columns (according
to statistical analysis and other factors) were further evaluated in Phase II.
Both procedures selected for Phase II were batch tests which utilize a 20:1
liquid-solid ratio. One used a 0.5 N pH 5 sodium acetate buffer solution as the
extraction fluid while the other used distilled, deionized water. Seven
additional industrial solid wastes were exposed to municipal waste leachate in
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the pilot scale columns (as in Phase I). They were also subjected to the EP
test and the two selected laboratory procedures. The results were compared,
analyzed statistically, and evaluated according to EPA's stated objectives for
the test. Then a draft TCLP was developed. (Francis and Maskarinec, 1986) The
Agency circulated the draft to interested groups outside the Agency for comment
and evaluated it for precision and ruggedness during Phase III.
A. General Comments
The Agency received forty general comments from 17 different commenters on
the research which led to the development of the leaching procedure. These
comments were submitted by public interest groups, government agencies, an
individual, a utility company, a manufacturer, various trade associations,
municipalities, and oil, gas, and chemical companies. All comments were
generally critical. Several comments asserted that the test method should be
based on both intrinsic properties of the waste and a fundamental understanding
of the mechanisms of leaching instead of empirical observations made by ORNL. A
number of comments stated that the TCLP does not take into account the time-
dependent nature of the leaching process. Other comments, including those from
oil companies and municipalities, voiced the concern that some specific types of
wastes were not included in the method development studies, particularly multi-
phase or oily wastes and municipal sewage sludge. For this reason, the comments
asserted that evaluation of eleven samples was insufficient to support EPA's
conclusion that further testing will not result in significant changes in the
composition of extracted fluids. Several comments questioned whether the
leachate generated 1n the field lysimeters was actually representative of
leachate from municipal sanitary landfills. Finally, several comments made
general remarks about the Inadequacy of the research supporting the method
development.
The Agency supports the use of the TCLP for identification of hazardous
wastes and believes that the Oak Ridge research demonstrates the applicability
of the test for this purpose. Insufficient information is available at this
time to develop identification criteria based on intrinsic waste properties and
fundamental mechanisms of leaching. The Agency has therefore elected to deve'.T
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an empirical test to evaluate potential hazard. The Agency believes that the
eleven wastes used 1n the Oak Ridge research are representative of a wide
variety of waste types, with the exception of highly alkaline wastes as
discussed elsewhere (USEPA, 1986a). These and other Issues related to the Oak
Ridge research are discussed in greater detail in the following sections.
B. Oak Ridge National Laboratory Testing: Phase I
Thirteen comments addressed Phase I of the ORNL research, and all were
critical of the initial development work for the TCLP. Five of these comments
criticized the generation of municipal waste leachate for the study. In
particular they noted that, since the lysimeters were operated for only two
months, the generated leachate cannot be considered representative of leachate
from actual landfills, which develops over the course of several years. One
comment asserted that the conditions represented in Phase I cannot be considered
as the worst possible case for three reasons: industrial wastes and small
quantities of hazardous wastes were not included in the lysimeters for the
generation of leachate; the time of leaching was too short to generate leachate
of maximum aggressiveness; and the potential Interactions of the industrial
wastes were ignored.
The Agency notes that the waste in the Oak Ridge lysimeters was allowed to
develop for three months before leaching with distilled water began. This
development period allowed biological degradation to become established in the
waste. Distilled water was then pumped through the lysimeters for two months to
allow the composition of the leachate to reach a steady-state before leaching of
the industrial wastes was initiated (Francis et al. 1984). The EPA's intent "was
to model the early stages of landfill decomposition. Leachate is believed to be
most aggressive 1n its mobilizing ability (acidity and complexation ability)
during the first few years of landfill life (Kimmell and Friedman, 1984).
Construction of the lysimeters with the three month development time prior to
the start of leaching was used as a reasonable approximation of conditions
during what was believed to be the most aggressive stage of landfill life.
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The Agency considered several mismanagement scenarios and decided on co-
disposal of hazardous waste with municipal refuse in a sanitary landfill as the
basis for the TCLP (as for the EP (USEPA, 1986a)). This scenario represents a
reasonable form of mismanagement with respect to potential for ground water
contamination. Available data indicate that few organic solvents or other
industrial liquid wastes are disposed of in municipal sanitary landfills (USEPA,
1986a), and as a result of stricter regulatory controls even fewer of these
types of wastes will be so- disposed in the future. The test is therefore
intended to approximate the leaching action of low molecular weight carboxylic
acids generated by the decomposition of household and commercial municipal
wastes in a sanitary landfill (USEPA, 1986a). Such landfills are usually
constructed in cells or lifts separated by layers of soil. Interactions of
industrial wastes and mixing of industrial and municipal wastes are assumed to
be minimal.
One comment questioned the relationship between the 1iquid-to-solid ratio in
a laboratory procedure and the actual time of leaching 1n the field. The
comment pointed out that the effect of the liquid to solid ratio on the
concentrations obtained in a batch leach test depends on the relative
aggressiveness of the extraction fluid and the total quantity of contaminant
available in the waste.
The Agency agrees that the effect of liquid-to-solid ratio does in fact
depend on many factors, Including waste composition, alkalinity, and extractant.
The relationship between Hqu1d-to-solid ratio in the laboratory and the actual
time of leaching 1n the field also depends on site-specific factors such as the
depth of the landfill and the local precipitation patterns. Therefore, the
relationship should be interpreted broadly in terms of relative differences and
not absolute values (Klmmell and Friedman, 1984).
One comment stated that the constituent :oncentrations in the leachate from
the Oak Ridge Industrial waste columns are higher than what would be found in
the field since the municipal waste leachate was used to leach columns
containing 100% industrial waste, instead of a mixture of industrial waste with
municipal waste.
The Agency again points out that the scenario modeled by the TCLP is the
same scenario modeled by the EP. The specific assumptions are that industrial
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waste is disposed of in a sanitary landfm along with municipal waste in a
ratio of 5:95 and that the leachate produced 1s primarily a function of the
biological decomposition of the municipal refuse (USEPA, 1986a). Municipal and
industrial wastes are not typically mixed in landfills but disposed of in
separate cells or lifts.
The development of target concentrations for evaluating the candidate
leaching procedures was also criticized. The comment asserted that the maximum
leachate concentration would be more conservative than the average concentration
used in the study and that the conservative approach to this situation would be
to assume a continuous release at maximum leachate concentration from an
infinite source.
The Agency disagrees with this comment. The TCLP is intended to model
chronic (long-term) exposure to contaminants in drinking water. EPA has no data
to demonstrate that a continuous release of contaminants at the maximum leachate
concentration occurs in the real world. Such an assumption would not constitute
a reasonable worst case, but an absolute worst case.
Two comments criticized the design and evaluation of the laboratory leaching
tests, stating that batch and column tests should not be compared, since batch
tests can reach a steady state condition while column leach tests always operate
under dynamic conditions. Also, no information on how well the field lysimeters
actually simulate landfill conditions was presented in the proposed rule.
The Agency points out that the same liquid-to-solid ratios were applied in
both the column tests and the batch tests, thereby providing a basis for
comparison. Regarding data on actual landfill leachate composition, few
sanitary landfills had (or have) leachate collection systems and so at the time
of method development little information was available from tests of actual
leachate composition. Available information from laboratory and pilot-scale
investigations are discussed in the reports on the Oak Ridge research (Francis
et al, 1984; Francis and Maskarinec, 1986).
Other comments criticized the method development work for not including
specific wastes, such as oily and multiphasic wastes and municipal sewage
sludge.
The Agency stated previously that it is not necessary to test every possible
waste during method development provided that the wastes tested represent the
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universe of waste types. One of the four wastes used in the Phase I tests was
in fact an API separator sludge from a petroleum refinery mixed with refinery
Incinerator ash (Francis et al, 1984). Additional studies are underway on the
use of the TCLP on oily wastes (see Sections IV.A and V.J of this document).
C. Oak Ridge National Laboratory Testing: Phase II
The Agency received nine critical comments in this area. One comment
criticized the selection of leaching procedures for development. It asserted
that a narrow range of extraction media was studied, none of which was
significantly different from the current EP test. It also asserted that the
Agency's rationale for the media selection was Incomplete and uninformative.
According to this comment, the Agency also failed to consider complexation or
the effects of co-solvents on mobility, and the solubility of non-polar organic
compounds when selecting the extraction fluids to be evaluated. Two comments
also made the point that two of the fluids tested ("CO2 saturated, deionized,
distilled water" and "deionized, distilled water") are not different since water
normally reaches equilibrium with CO2 in the atmosphere. Also, the acetate
buffer solution 1s only a minor modification of the existing EP.
The Agency responds that in the disposal scenario modeled by both the EP and
the TCLP, the leaching medium is composed of precipitation onto the landfill
combined with decomposition products from municipal wastes. These decomposition
products consist primarily of carboxylic acids, one of the most common of which
is acetic acid. There 1s no reason for the extraction fluid for the TCLP to be
radically different from that used 1n the EP, since the tests are both based'on
the same assumptions. The acetate buffer was selected over the acetic acid used
in the EP to make the test easier to perform. This rationale is discussed in
several reports on the test method development (Francis et al, 1984; Kimmell and
Friedman, 1984; Francis and Maskarinec, 1986; USEPA, 1986a).
The assumptions of the disposal scenario preclude the presence of
significant concentrations of solvents in the extraction medium. Carboxylic
acids, which are complexing agents, made up 60% to 80% of the TOC of the
lysimeter leachate (Francis et al, 1984) so the complexing effect of these
compounds is accounted for. Comparison of the candidate extraction fluids with
the lysimeter leachate indicates that the effects of complexation and solubility
are adequately represented by the laboratory procedure.
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Another comment criticized the limited number of wastes used in Phase II.
Only two of the original eleven wastes were used 1n the second phase of the
study to validate the TCLP. According to this comment, the limited number of
wastes in the study does not validate or even recommend the test for
characterizing all solid wastes.
The Agency points out that four industrial solid wastes were used in Phase I
and seven additional wastes were tested in Phase II. These eleven wastes
represented a wide range of waste composition and characteristics. Phase I
wastes consisted of heavy ends and column bottoms from the production of tri-
and perchloroethylene, a paint production sludge, a mixture of refinery
incinerator ash and API separator sludge, and an electroplating wastewater
treatment sludge (Francis et al., 1984). The wastes used in Phase II were an
industrial wastewater treatment sludge, ammonia lime still bottoms, a mixture of
organic solvent and sludge, a mixture of organic solvent and vermiculite, a
mixture of still bottoms and wastewater treatment sludge, a mixture of still
bottoms and vermiculite, and a utility fly ash (Francis and Maskarlnec, 1986).
It is not necessary to test every waste if the wastes which are tested
adequately represent the universe of waste types. Phase III of the TCLP
development consisted of tests to evaluate Intra- and Inter-laboratory
ruggedness and precision. Two wastes were used in the Phase III evaluation
(USEPA, 1986a).
Another comment expressed some confusion about references to the "lyslmeter
field model" and the ability of different leachate media to duplicate "field
results" since there were no leaching tests of industrial wastes in field
lysimeters.
The Agency points out that the industrial wastes were exposed to lysimetefr
leachate in pilot scale columns, 38.7 cm in diameter by 30.5 cm high, which were
located adjacent to the lysimeters (Francis et al, 1984). These tests are
referred to as field tests to distinguish them from the laboratory tests.
D. Statistical Treatment of Data
One comment addressed in detail both the multivariate analysis and other
aspects of the statistical treatment of data from the ORNL studies. It asserted
15
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that the Mahalanobls distance statistic (used to evaluate the various extraction
fluids) has a highly non-normal distribution and is thus unsuitable for a
multivariate type of analysis. Specifically, using such skewed data violates
the assumptions behind the multivariate analysis procedure and may result 1n
false conclusions drawn from the analysis. Also, significant waste/media
interactions confound the multivariate analysis and preclude the ability to make
comparisons across all wastes. When comparing test results on a waste-by-waste
basis, there 1s no evidence for a single, clearly superior extractant. Another
comment asserted that a review of the ORNL data shows that the best long-term
average predictor 1s a test which uses distilled water as the leaching medium.
The Agency anticipated criticism of the statistical analysis of the Oak
Ridge data, and attempted to address these critics in advance by submitting the
data to several different analyses. The results of these analyses were
discussed extensively 1n the TCLP background document prepared for the June 13,
1986, proposal (USEPA, 1986a). The Agency recognizes that no single leaching
procedure will be able to accurately predict concentrations of all compounds in
all waste matrices. The intent of the Investigation was to determine what
procedure provides the best representation over all conditions. In order to
evaluate this, the results must be compared across all waste types. The Agency
points out that other factors were considered 1n development of the TCLP besides
the results of the statistical analysis. These factors Include practicality,
ease of operation, cost, reproducibility, and applicability to both organic and
inorganic contaminants.
The Agency is continuing to investigate the use of distilled water as the
extractant for testing of volatile organics. Previous research has shown that
the leaching of organics is not affected by changes in the leaching fluid,
whereas the composition of the leaching fluid is important for the leaching of
inorganics (Warner et al., 1981). It is also desirable to use the same leaching
fluid for all segments of the test. The TCLP as finalized for use in the
Toxicity Characteristic requires an acetate buffer leaching fluid for most
wastes and an acetic acid leaching fluid for highly alkaline wastes.
Another comment stated that evaluating the batch tests on the basis of only
one organic component, naphthalene, does not validate the procedure.
Naphthalene was not the only organic compound evaluated in development of
the TCLP. Other compounds included in the Phase I evaluation were di- and -
16
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tn'chloroethylene, d1- and trichloroethane, toluene, xylenes, and
hexachlorobutadlene (Francis et al, 1984). Phase II evaluation included 10
inorganic and 12 organic compounds (Francis and Maskarinec, 1986).
One comment pointed out that the accuracy of the proposed acetate buffer is
extremely poor for a very Important class of chemicals (i.e. chlorinated
compounds). On an average, the acetate buffer extracted only 22% of the target
concentrations for this class of compounds In the Phase II tests. The comment
raised the concern that chlorinated organics will be under-represented by the
TCLP.
The Agency replies that the poor extraction of chlorinated organics
(generally classified as volatiles) in Phase II of the research was noted.
These results led the Agency to conclude that volatiles were being lost as a
result of the air pressure filtration and the headspace within the bottle
extractor. Consequently, the Agency determined that a different device was
needed to improve the recovery of volatile compounds. Thus, the Zero Headspace
Extractor (ZHE) was developed to minimize the loss of volatiles.
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III. Research Supporting Leaching Procedure Development: Ruggedness and
Precision Evaluation
Phase III of the EPA's research program consisted of evaluating the proposed
procedure for precision and ruggedness on an intra-laboratory basis and
conducting an inter-laboratory collaborative study. The precision evaluation
was performed by two laboratories which used two industrial wastes. Precision
of the test for non-volatile components was judged acceptable, while the
evaluation of precision for volatile components was hampered by problems with
equipment and laboratories and changes in the test protocol. Thus, the Agency
was evaluating precision of the test for volatlles when the Federal Register
proposal appeared on June 13, 1986. The final report on precision of the TCLP
for volatiles was made available to the public on July 9, 1986 (51 FR 24856).
Ruggedness testing was conducted with the same industrial wastes used in the
precision evaluation. The Agency concluded that the proposed test is adequately
rugged. Evaluation of the procedure for volatiles was ongoing at the time of
the June 13, 1986 proposal. The final report on ruggedness was made available to
the public on July 9, 1986 (51 FR 24856). An Agency sponsored collaborative
study (involving 26 laboratories, 5 wastes, and both volatile and non-volatile
parameters) was also in progress at the time of the June 13, 1986 Federal
Reqister proposal. The results of this study were made available to the public
on September 19, 1986 (51 FR 33297).
The Agency received thirty-three comments which addressed various issues
related to this research. The comments addressed the collaborative evaluation
and the ruggedness and precision evaluations. All comments are summarized
below.
A. Collaborative Evaluation
The Agency received a total of sixteen comments which addressed the
collaborative evaluation. One expressed support for the design of the study.
However, most criticized the lack of complete information on the collaborative
study available at the time of the June 13, 1986, Federal Register notice.
Several also addressed the study coordinated by Lancy Environmental Services and
funded by six trade associates (Lancy, 1986).
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Several commenters were interested In including a particular type of waste
(i.e. sewage sludge, fly ash, oily waste) in the study.
The Agency believes that 1t 1s unnecessary to perform precision studies on
all wastes that may be subject to the TCLP since such an effort would be very
costly in terms of time. In precision studies, it 1s more important to test a
range of wastes (in terms of physical and chemical characteristics). The Agency
also points out that the trade association study included many of the suggested
wastes, and the results obtained were not significantly different from the
results of EPA's study.
Twelve comments expressed a need for more information and urge the agency
not to promulgate the TCLP until the results of the collaborative study have
been made public and the regulated community has had a chance to comment. One
comment stated that the proposed regulations are premature. It also stated that
a thorough analysis of the comprehensive multl-laboratory evaluation results
should have been conducted before the proposed rules were issued, rather than
publishing the proposed rules with the provision that the collaborative study
results would be available for analysis at a later date. According to the
comments, the TCLP test simply has not had the benefit of appropriate peer
review.
EPA notes that the results of the collaborative study (completed in
September, 1986, and noted 1n the Federal Register at 51 FR 33297) indicate that
the TCLP can be applied consistently by a diverse group of organizations. Total
recoveries for both sem1-volat1le organic compounds and metals were sufficiently
good to indicate that the variability falls within reasonable statistical limits
(95 percent confidence level) for these two groups of constituents. The
pesticide results were distorted by the limited amount of data and the wide .
range of detection limits reported by the participating laboratories. The
Agency believes that a larger data set would yield results comparable with those
derived for the semi-volatile organic compounds.
Nine comments referred to the study conducted by Lancy Environmental
Services and funded by six trade associations and recommended that the Agency
consider the results of this study prior to finalizing the TCLP.
EPA states that the results of the inter-industry association study (also
available in- September, 1986) indicate that the TCLP and EP toxicity tests are
19
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similar in precision. The relative standard deviation for both tests range from
approximately 10% to 100% depending on waste type and parameters measured. The
intra-!aboratory precision was considerably better than the inter-laboratory
precision. Both the lack of homogeneity in the wastes and the resulting
difficulty in obtaining representative samples contributed significantly to the
uncertainty surrounding the TCLP values.
Additional comments addressed the collaborative study report made available
in September, 1986 (S-Cubed, 1986a). Several of these suggested that EPA should
have included a comparison of the TCLP and the EP in the collaborative study.
EPA decided that since both the Lancy study (Lancy, 1986) and a study conducted
by the Electric Power Research Institute (EPRI, 1986) Included a comparison of
the TCLP with the EP, the Agency should concentrate Its resources on the TCLP.
Other comments requested that EPA publish a final report on its
collaborative study (the September report contained only preliminary results for
volatiles) and make the final report available for public review and comment.
One commenter recommended that the final report should contain the original data
reports submitted by participating laboratories.
The Agency notes that a draft final report on the collaborative study has
been prepared (S-Cubed, 1986b). Since the conclusions of the study were not
changed in the final report, the Agency determined that it was not necessary to
notice the report for comments again. Inclusion of the laboratory data reports
would greatly increase the volume of the report without significantly adding to
its content. These reports are available in the docket.
Some comments questioned the method used by the referee laboratory to
identify outlier data points, and one participating laboratory noted
discrepancies between its reported results and the data presented in the
September report.
The Agency points out that the method used by the referee laboratory to
determine outliers 1s described more fully in the draft final report (S-Cubed,
1986b). Data reported on compounds other than those identified as "target
compounds" by the referee laboratory were not included in the report.
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B. Ruggedness Evaluation
Three comments criticized the ruggedness evaluation and express a need for
additional testing. These comments asserted that the Agency failed to complete
a ruggedness study of the TCLP at the time of the June 13, 1986, proposal. The
comments also questioned the promulgation of the new test until the precision,
accuracy, and ruggedness have been fully evaluated.
The Agency refers the commenters to results of the ruggedness evaluation
described in the July 9, 1986, issue of the Federal Register (51 FR 24856), and
the discussion of those results in the TCLP background document supporting the
Land Disposal Restrictions Rule (US EPA, 1986b).
C. Precision Evaluation
The Agency received fourteen comments which addressed the precision
evaluation, and all were critical of the agency's procedures and results.
One trade association stated that the reported coefficients of variation for
non-volatile components were quite high and that the precision of the test for
low levels of non-volatile compounds was poor. The comment recommended that EPA
reevaluate whether or not the precision of the TCLP test is adequate. Four
comments stated a need for further testing and evaluation of method precision.
They recommended that EPA vigorously pursue Its methods activity on evaluation
and development and then make Its results available for public comment before
final promulgation.
Two comments expressed concern about the lack of data on the precision of
the test for volatiles at the time of the June 13, 1986, proposal. They urged
EPA to ensure the development of adequate precision and accuracy data for
volatile organics. One comment questioned whether disposal companies will be
unwilling to rely on such a highly variable test for assurance of a waste being
nonhazardous.
EPA notes that 1t conducted single and multl-laboratory evaluations of the
precision of the TCLP for volatiles and non-volatiles, as did two industry
groups (EPRI and the trade association study coordinated by Lancy Environmental
Services). These efforts support the adequacy of the precision of the TCLP and
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also support EPA's contention that precision over the existing EP has been
improved, 1f only slightly. Specifically, these studies show that both sampling
and analytical variability contribute significantly to the total variability of
the TCLP. (S-Cubed, 1986a; S-Cubed, 1986b; Lancy, 1986; EPRI, 1986).
EPA refers the commenters to Table 3 which shows the mean and median
relative standard deviations for the major classes of analytes (averaged over
the various laboratories, samples, and individual analytes for each of the three
collaborative studies). It should be noted that the average or median percent
relative standard deviation for each class Includes the variability attributed
to different waste streams, different samples of the same waste stream,
different laboratories, the leaching procedure, different analytes, and the
analytical procedures. Although a quantitative analysis of variance has not
been performed on these data, the collaborative studies indicate that the
largest contributors to this variability are the differences between samples of
the same waste. The variability of the TCLP is likely to be as significant as
the analytical method variability. However, it is reasonable to assume that,
since the analytical method variabilities are considered acceptable, the TCLP
variability is acceptable. The focus on reducing variability should be placed
on sampling procedures as well as the leaching test and subsequent analyses
since they contribute significantly to total variability.
Some comments expressed concern about poor reproducibility of the test for
metals. One comment referred to a study conducted by a trade association which
showed the metal concentration to be very sensitive to sample preservation,
particle size distribution, and variations 1n lab procedures. Another comment
asserted that the test is inadequate because they observed a relative standard
deviation greater than 100% in the results of tests performed by contract
laboratories. A utility company asserted that the precision of the TCLP should
be evaluated for all 8 EP metals, since performance varies with the analyte.
The Agency responds that, as demonstrated by all three collaborative studies
mentioned previously, precision of the TCLP for metals is within the realm of
acceptability. In particular, the EPRI study concluded that, the precision of
the TCLP 1s at least as good as that of the existing EP test.
A minerals processing firm believed that the precision data are misleading
in that the degree of precision is primarily due to the aggressiveness of the
leach liquor.
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TABLE 3. RESULTS OF TCLP COLLABORATIVE STUDIES
% RELATIVE STANDARD DEVIATION
% RSD EPA IIA EPRI
Chlorlnated
Volatiles:
Mean
Medi an
Range
77
76
17-127
54
42
24-78
—
Non-Chlorinated
Volatiles:
Mean
Median
Range
71
69
27-144
-
-
Semi-Volatiles:
Mean
Median
Range
85
81
0-164
-
-
Pesti cides:
Mean
Median
Range
160
160
7-278
-
-
Metals:
Mean
Median
Range
67
67
3-129
31
21
7-63
49
52
9-104
EPA: multi-laboratory collaborative study coordinated by S-Cubed
IIA: inter-industry association study coordinated by Lancy Environmental
Services
EPRI: Electric Power Research Institute Study of utility wastes
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The Agency agrees that the more aggressive the leaching media, the more
reproducible the results (for metals). One need only consult the results of
acid digestions to confirm this.
An oil company stated that EPA needs to evaluate the precision and
ruggedness of the TCLP for multiphase samples.
The Agency points out that one of the wastes used for evaluation of
precision for volatile analytes was a mixture of API separator sludge and
electroplating waste (S-Cubedr 1986d). Studies conducted using oily wastes led
to the Agency's decision to specify a glass fiber filter for the TCLP rather
than the membrane filter used in the EP based on improved filtration and
reproducibility for the oily wastes studied (ERCQ, 1985). Further studies are
underway to investigate whether changes to the TCLP can enhance the tests
ability to model the behavior of oily wastes in a land disposal environment.
A chemical company asserted that too much emphasis has been placed on
precision of the test since sampling of waste streams 1s not a very precise
operation. The company believes that the procedure can be simplified and made
less expensive with no loss of data value.
EPA responds that 1t has made a serious, conscious effort to produce the
simplest procedure possible. As indicated in other sections of the preamble and
background document, EPA is also investigating further ways to simplify the
method (principally the ZHE portion) and thus may propose more changes. The
Agency agrees that sampling contributes significantly to the overall variability
of the procedure, as shown by some of the collaborative studies. Attention must
be paid to reducing all sources of variability in the procedure.
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IV. General Leaching Procedure Issues
Various aspects of the procedure were reviewed by EPA and others, and a
number of topics were Identified as Leaching Procedure Issues. These issues
include: (1) the accuracy of the TCLP; (2) the procedure for moderate to highly
alkaline wastes; and (3) the pre-screening test. Seventy-three comments
addressed these issues. The comments were made by trade associations, the
petrochemical industry, mining and mineral companies, waste management firms,
other private industries, municipalities, other government agencies,
environmental consulting firms, and private utility firms and research
laboratories. A detailed discussion of each issue follows.
A. Accuracy of the TCLP
EPA was directed by the HSWA to make the EP more accurate. The experimental
program for developing the TCLP was intended to provide an accurate model of a
field co-disposal situation. One of the leaching procedure Issues is whether
the method is adequate 1n this respect. Twenty-four comments criticized the
accuracy of the method.
Most of these comments recommended additional testing to improve the level
of accuracy thus far demonstrated by the TCLP. These comments noted that, in
the development of the TCLP, only eleven wastes were tested. Increasing the
variety of wastes and the number of extractions performed may result in method
refinements that, 1n turn, will enhance the accuracy. Several specific types of
wastes were suggested for additional testing, including oily waste, organic
chemical wastes, and municipal wastes. Two comments questioned the Agency's
basic definition of accuracy and its accompanying documentation described in the
proposed rules. Five comments stated that they do not believe that the 182%
relative standard deviation reported in the proposed regulation is a sufficient
level of accuracy for meeting mandated requirements of the HWSA. One comment
suggested that the procedure be repeated several times on each waste stream in
order to improve the accuracy of determining the hazardous constituents over a
period of time.
The Agency believes that the accuracy of the TCLP 1s adequate in terms of
the test's ability to indicate the potential for wastes to pose a hazard if
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I
mismanaged. The laboratory test system reproduces the field lysimeter leachate
concentrations for about three-fourths of the target compounds within one
standard deviation of the distribution. The field-scale lysimeters are the most
practical method available for simulating the behavior of actual landfills. The
Agency also believes that the eleven wastes tested during the method development
process adequately represent the range of waste types encountered 1n the real
world (with the exception of alkaline wastes, which are discussed below).
Several comments suggested that the TCLP does not accurately measure the
hazard posed by oily wastes because it assumes that liquid wastes (both aqueous
and non-aqueous) behave in an identical fashion in the subsurface environment.
The comment also contended that the Agency provides no evidence to support this
assumption and therefore urges the Agency to conduct further investigations into
the behavior of oily wastes.
The Agency points out that the TCLP is designed to predict the release of
contaminants from landfilled wastes into the subsurface environment. The
mobility of the released aqueous or non-aqueous phases through the saturated and
unsaturated zones of the subsurface 1s addressed by ground water modeling.
Three of the eleven wastes Investigated during TCLP development represented oily
wastes. This research demonstrated that non-aqueous liquids are released from
landfilled wastes. Such release is modeled by the liquid/solid separation step
of the TCLP. Additional investigations are underway to evaluate whether
modifications the the filtration step can more accurately predict the release of
aqueous and non-aqueous liquids into the subsurface.
B. Treatment of Highly and Moderately Alkaline Wastes
EPA is concerned that the potential hazard posed by alkaline wastes may be
underestimated by the acetate buffer system initially chosen for the TCLP.
Specifically, EPA believes that an increase in the leaching of inorganic and
some organic species may be observed as the alkalinity of the wastes becomes
exhausted (due to continuous contact with an acidic leaching medium). The TCLP
acetate buffer leaching fluid may therefore not adequately account for the
leaching of heavy metals from wastes of moderate to high alkalinity. Thus, EPA
proposed a two leaching fluid system for the TCLP. The Agency chose to base the
26
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1
strength of the alkaline waste leaching medium on 2 milHequivalents of acid per
gram of waste (the maximum amount of acid allowed in the EP) for wastes of
moderate to high alkalinity and 0.7 mill1equ1valents per gram of waste for other
wastes. This dual leaching fluid system is not proposed for evaluating volatile
compounds since these compounds are expected to be unaffected by slight changes
in acidity.
Eighteen comments were concerned with the application of the TCLP to
alkaline wastes. Six of these comments noted that no highly alkaline waste was
included 1n the development of the TCLP and that no conclusions therefore can be
made concerning the actual behavior of these wastes. Four comments stated that
the leaching medium in the municipal landfill 1s relatively constant regardless
of the type of Industrial waste co-disposed. Therefore, there should be a
single leaching medium for the TCLP that applies to all types of wastes. Six
comments contended that the more aggressive leaching medium used for the TCLP is
not justified because 1t 1s much more acidic than the actual leachate examined
in the ORNL Phase II study and in the collected data on municipal landfill
leachate.
Three comments expressed concern about the inaccuracy that might appear in
subsequent analyses of alkaline wastes as a result of the more acidic leaching
medium. One comment stated that the procedure used to determine which leaching
fluid should be employed may result 1n very different results from tests
performed on very similar wastes. Based on the alkalinity test, two wastes may
be subjected to different leaching media, when the wastes actually behave very
similarly in the field. A mining and metal industry comment expressed concern
that use of acetic acid as the leaching medium would falsely exaggerate the
potential availability of metals for migration. A municipal sewer district '
feared that I1me-stab1l1zed sewage sludge might be reclassified as hazardous
when tested withr the TCLP procedure for alkaline wastes. The comment maintains
that according to actual disposal practices, sewage sludge is never exposed to
acidic leaching conditions.
The Agency acknowledges the fact that highly alkaline wastes were not
included in the TCLP development program. For this reason, EPA is concerned
that the acetate buffer leaching medium may underestimate the potential hazard
posed by such wastes. Therefore, a leaching medium containing 2
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mi Hi equivalents of acid per gram of waste (the maximum amount of acid allowed
by the EP) 1s required for wastes of moderate to high alkalinity. A leaching
medium containing 0.7 milliequlvalents of acid per gram of waste is required for
all other wastes and for all analyses where volatlles are involved.
C. Pre-screen Test
The pre-screen test consists of a total waste analysis using SW-846 methods
and determines if the waste contains enough specific compounds to exceed the
regulatory level. This test assumes that all of the compound leaches from the
waste. If, based on such an analysis, one can be certain that the regulatory
level cannot be exceeded, the TCLP does not need to be performed. Thirty-one
comments addressed the pre-screen procedure. Nineteen comments totally
supported the Agency's proposed procedure for providing a method of avoiding
excessive analytical cost and time.
Several comments requested additional guidance from the Agency regarding
performance of the pre-screen test, and one comment suggested that the pre-
screen test be incorporated as a provision of 40 CFR 261.24.
The Agency does not believe that 1t is necessary for the method to include a
step-by-step description of the pre-screen test. The pre-screen test directs
generators to: conduct total waste analyses using SW-846; assume that all the
constituents, if present in the waste, migrate into the leachate; and determine
whether the constituent has the potential to exceed the appropriate regulatory
level. Selecting the most appropriate SW-846 method for a total analysis is a
waste-specific determination. Thus, it is best performed by the laboratory
performing the analyses. The calculation of maximum extract concentration is
easy for non-11qu1d wastes. The waste concentration (mg/kg) is merely divided
by a factor of 20 to predict the maximum possible TCLP extract concentration.
The calculation 1s only slightly more difficult for wastes containing liquids.
This calculation requires separate analytical determinations of the relative
constituent loadings of both liquid and solid phases and a simple volume
weighted average of the concentration of the constituent 1n the liquid phase and
the concentration in the solid phase (mg/kg) divided by a factor of 20. EPA
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believes that these calculations are straightforward enough that they are not
spelled out 1n the method.
Other comments offered general support for the pre-screen procedure but make
suggestions for Improvements. Three comments suggested that, In addition to a
pre-screen test, the generator's knowledge and experience should be used in
deciding what constituents 1n the waste require analysis. Another comment
advocated the establishment of a recognized method whereby a generator can avoid
the expense of routine analyses of constituents known to be absent from a waste
stream.
The Agency responds that process knowledge and knowledge of the waste itself
is allowed under the Toxicity Characteristic (40 CFR 262.11) for determining
whether wastes are hazardous as defined by the hazardous waste characteristics.
One comment suggested that it 1s unnecessary to analyze the total waste 1f a
single phase of the waste contains such a high concentration of a constituent
that the regulatory threshold would be exceeded regardless of the concentration
in the other phases or extracts. Another comment suggested that volatlles be
measured 1n the aqueous phase of the waste because the leachate derived from the
TCLP probably would not contain greater concentrations of volatlles than in the
aqueous phase of the waste. The comment stated that this could be especially
applicable for oily waste.
EPA generally agrees. However, this may be true only when the waste
contains a small "solid" phase (e.g., less than 10%). EPA has no data that
would support this contention.
Several comments criticized the Agency's proposed pre-screen test. One
comment stated that the cost of performing the pre-screen test will exceed the
cost of performing the TCLP.
EPA agrees that the cost of the total analysis may indeed equal or even
exceed the cost of performing the TCLP and running subsequent SW-846 analyses.
However, many generators have the results of total constituent analyses of their
wastes already available which can be used 1n this evaluation.
Another comment questioned whether commercial waste disposal firms will
accept the results of a pre-screen test in 11eu of a complete TCLP.
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EPA responds that the pre-screen test provides generators with the means by
which to demonstrate tha.t their wastes either do not contain certain
constituents, or that if they do contain these constituents, to predict whether
the maximum possible TCLP extract concentration falls above or below the
appropriate regulatory level. The pre-screen test 1s a part of the method and
its results must be accepted as equivalent to the results of the leaching
procedure itself.
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V. Specific Technical Comments on the TCLP
One half of all the comments which the Agency received addressed specific
aspects of the TCLP. The areas of comment included the extraction vessels
(ZHE), the agitation apparatus, the borosilicate glass fiber filter, the
leaching media and other reagents, the particle size reduction requirements,
specific steps in the extraction procedure, the quality assurance requirements,
and the relationship between the TCLP and the leaching tests used in the
Agency's delisting program.
A. Extraction Vessels (ZHE)
Fifty-nine comments expressed concern regarding the extraction vessels
specified. Five comments voiced qualified support for the use of the ZHE for
volatile compounds and fifty-four comments criticized the use of the ZHE for
volatiles.
Several coranents expressing qualified support for the ZHE suggested design
improvements to further minimize loss of volatiles. These comments recommended
that the internal volume of the ZHE be reduced to approximately 110 percent of
the volume of the waste charged Into the ZHE 1n order to further minimize the
headspace and loss of volatiles. Another comment stated the ZHE 1s of high
quality design even though it 1s expensive.
The Agency agrees that the ZHE design 1s of high quality and that the
internal volume of the ZHE should be reduced 1n order to minimize the headspace.
Therefore, the method has been changed to clarify that, prior to charging the
ZHE with sample, the piston should be moved to a position which will minimize
both headspace and the distance the piston must move to express the initial
liquid phase of the waste.
Thirteen comments critical of the use of the ZHE questioned the availability
of the apparatus and are concerned about the manufacturers' ability to meet
demand. A typical comment stated that the commercial availability should be
assured prior to the effective date of the regulation.
EPA replies that the ZHE is now available through additional manufacturers.
One manufacturer reports almost a full year's Inventory currently 1n stock.
Also, the accessories needed for the TCLP (i.e., glass fiber filters, Tedlar
bags, syringes, etc.) are now readily available.
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One of the comments addressing the availability of the ZHE pointed out that
the manufacturers experienced some serious problems during the Initial testing
of the ZHE.
In response, the Agency explains that one Initial problem was a loss of
volatiles through pressure and liquid release valves. This problem has been
rectified through changes in the TCLP (including a sequence of steps that will
allow the equipment to be checked for leaks). See Step 4.2.1 for further
information.
Many of the comments which criticized the ZHE addressed the inconsistencies
between the ZHE and extraction bottles. Several of these comments requested
data indicating the necessity for a device like the ZHE. For example, one
comment asserted that EPA has not justified the need for more complicated and
more expensive laboratory equipment such as the zero-headspace extraction
vessel.
In response, the Agency refers the reader to the S-Cubed report (S-Cubed,
1986c) on single laboratory testing using the conventional apparatus. The
report concludes that the conventional TCLP extraction vessel (bottle) 1s not
feasible for extraction of volatile compounds. Recoveries were usually less
than 25% for spiked samples. The losses were attributed to the headspace
present in the bottles during extraction and the vacuum filtration used for
liquid/solid separation. These results led to the development of the ZHE.
One comment addressing the inconsistencies between the ZHE and the bottles
supported the use of a standardized method of extraction for volatiles and non-
volatiles in order to obtain comparable results. Another comment revealed that
different analytical results for non-volatile and inorganic constituents were
obtained using the two devices and suggests that the difference occurs because
the agitation action in the ZHE differs from that of the extraction bottles.
Other comments questioned the size of the ZHE (specified as 500 milliliters)
when it is known that the non-volatile sample size of 100 grams will require a
volume of more than 2000 milliliters.
EPA states that the ZHE is not intended for analysis of non-volatile
compounds. The wording in the procedure has been modified to emphasize that the
ZHE is to be used only for volatile analysis (See discussion in the March 10,
1986, TCLP Background Document (USEPA, 1986a)).
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Another area of concern was the corrosion of the stainless steel walls of
the ZHE. This corrosion could cause contamination of the leachate, producing
unrepresentative results. Many comments which are critical of the use of the
ZHE expressed concern in this area. One comment asserted that the use of a
stainless steel vessel for extraction of inorganic materials should be avoided
since the nature of the wastes, when combined with the potentially abrasive
action between the waste and the container walls, may contaminate the leachate
with elements from the steel. Another comment stated that the stainless steel
could corrode, producing high blank levels and unrepresentative results.
The Agency points out that the ZHE is only intended for analyzing volatiles,
thus potential metals contamination is not a concern.
One comment remarked that, if the ZHE is required, then the borosilicate
glass bottle should also be specified for the metals analysis.
EPA agrees. The TCLP has been modified to recommend the use of borosilicate
glass bottles over the use of flint glass bottles when analyzing for inorganics.
Flint glass may cause interferences in the inorganic analysis. However, flint
glass can be used in the analysis of non-volatile organics. Also, "plastic"
bottles can be used 1f only inorganics are to be investigated.
Six comments which are critical of the use of the ZHE stated that the
specified volume of 500 ml for the ZHE is not adequate to contain the sample
size required for extraction. Several of these comments suggested that a
problem exists with the ZHE for waste streams containing 0.5% (or greater)
solids. For example, one comment stated that, 1n order to obtain a 25 gram
solid sample for extraction, the filtering process would produce about five
liters of filtrate. The capacity of the ZHE is only 500 ml. Therefore, the
contents would be exposed to the atmosphere up to ten .times during the
procedure. As a result, one comment asked if the ZHE 1s of any benefit if it is
opened and closed too often when trying to meet the sample size criterion.
Regarding use of the ZHE with a waste stream containing low percent solids,
the Agency points out that the TCLP specifies only a maximum (25 grams of solid)
and not a minimum sample requirement for the volatile procedure. The proposed
method recommended that the ZHE be charged only once. The method has now been
modified to state clearly that the ZHE should only be charged once and that
there is no minimum sample size requirement as long as enough leachate is
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generated to perform the necessary analyses. If insufficient leachate is
generated by a single extraction, multiple extractions may be performed and the
leachate combined for analysis.
One correnent suggested that for maximum pressure of 50 psi, the ZHE could be
made with less metal. This would make it possible to have a larger vessel and a
bigger sample size.
In response, the EPA asserts that extraction with the ZHE may involve
pressures greater than 50 psi. For safety reasons, the walls of the vessel
should not be made thinner. Moreover, the Agency believes that the specified
sample size is more than adequate for analyzing volatile compounds.
Several comments expressed concern over the difficulty they experienced in
cleaning the ZHE. For example, one comment was concerned that the Viton "o"
rings absorb organic compounds, regardless of the attempts to clean the
material.
The Agency points out that the Viton "o" rings should be replaced
frequently, as stated in step 4.2.1 of the TCLP method, thereby reducing the
risk of contamination.
Another comment described the difficulty encountered while cleaning syringes
and Tedlar bags for re-use. This comment continued by urging the EPA to
consider VOA vials, which are less expensive, portable, durable, and disposable
or easily cleaned, for collection of the TCLP extract.
The EPA states that Tedlar bags are not re-usable. VOA vials can be used to
store extraction fluid. However, they are not recommended for direct
collection of the filtrate because there 1s no way to connect the VOA vial with
the ZHE in such a manner as to exclude headspace.
One comment suggested improving the ZHE to allow ease of cleaning.
Specifically, this comment recommended that the spacing of the support screen
for the filter be made only as small as absolutely necessary.
The Agency states that the specified size of support screens are needed to
protect the GFF filter from abrasion by the waste.
A few of the comments stated that sometimes it is impossible to clean the
ZHE and that it has to be discarded. As a remedy to the situation, one comment
urged the use of a disposable liner.
In response to these comments, the Agency explains that the concept of
disposable liners has been considered but was rejected as impractical. One.
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reason 1s that an exact fft Is required for the piston Inside the ZHE barrel,
and the use of a Uner will not allow a secure fit. Also, the Agency Is
currently Investigating cleaning procedures to be included In the method. If
the ZHE 1s found to be impossible to clean, then the manufacturer should be
contacted for inspection of the device.
Some of the comments concerned with the extraction vessels expressed an
interest in safety precautions with respect to pressure build-up. One comment
asserted that EPA should evaluate the safety aspects relative to wastes which
could react and produce off-gases. Specifically, they were concerned with
possible pressure build-up inside the ZHE from reactions of highly alkaline
wastes. A few of the comments suggested that the ZHE should be equipped with a
device for releasing pressure. One comment stated that a pressure release valve
on the ZHE might remedy the situation. However, another comment suggested that
venting of gases due to pressure build-up may result in the loss of volatiles.
Recognizing the possibility of pressure build-up, EPA states that the
stainless steel containers have been designed to accommodate high pressures.
The ZHE is also equipped with pressure release valves. However, when using
extraction bottles, EPA recommends venting the bottles shortly after the waste
contacts the extraction fluid. Regarding the loss of volatiles during venting,
the EPA points out that it is not possible to completely avoid a loss of
volatiles although the TCLP is designed to minimize losses.
Several comments offered possible alternatives to the ZHE. Specifically,
these comments asserted that comparable results may be obtained with a standard
40 ml glass VOA vial with a Teflon-Hned septum for sample extractions. They
recommend that the Agency determine whether or not a simpler system would yield
comparable results for the volatile organlcs. Additional comments suggested
that a screw-top bottle with a suitable cap liner (filled full) 1s an adequate
zero-headspace device. One comment requested that the Agency provide data
demonstrating that the ZHE produces more representative results than other
existing devices which are more readily available and easier to use.
EPA responds that 1t 1s investigating the option of a simpler extraction
system. However, the 40 ml VOA vial is not a suitable alternative. A 40 ml VOA
vial would not permit solid-liquid separation to be performed under minimum
headspace for the specified sample size. EPA's studies of precision for
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volatile compounds using both the ZHE and the conventional apparatus indicate
that the device does reduce losses. (S-Cubed, 1986c; S-Cubed, 1986d)
B. Agitation Apparatus
Thirteen comments criticized the rotary agitation apparatus. The areas of
concern Include the effects of rotation on particle size, the use of the
rotation apparatus with the ZHE, the rate of agitation, and the agitation time
requirement.
Several of these comments stated that the rotary apparatus will cause
particle size reduction, resulting 1n non-representative extractions of
constituents. One comment stated that the rotary cells used 1n the procedure
may cause mechanical grinding of monolithic wastes. Another comment stated that
the agitation apparatus will produce unrepresentative high concentrations of
contaminants (based on the chipping that will occur during agitation). Another
comment stated that the TCLP 1s Inappropriate for vitreous and other hard waste
forms since the tumbling process grinds the waste Into finer and finer
particles. Also, the cement and lime based waste forms may paste up during the
TCLP, thus limiting the exposure of the waste to the leachate. Therefore, this
comment questioned whether or not the TCLP ensures a complete and effective
contact between the waste sample and the leachant.
The Agency replies that the extraction is intended to be representative of
leaching over a long period of time. In order to simulate this long-term
leaching, batch leaching tests with agitation are required to ensure that
equilibrium between the extractant and the sample is achieved within eighteen
hours. For additional information, the Agency refers to the Background Document
prepared for the "EP test (US EPA, 1980).
Some comments which addressed the use of the rotary agitation apparatus
disapproved of the its use with the ZHE. For example, a few of the comments
pointed out that the rotary apparatus and the extraction vessel must be
purchased from the same vender 1n order to assure compatabi1ity.
In response, EPA asserts that most agitation apparatuses and extraction
vessels are compatible with minor adjustments. Therefore, the devices may be
purchased from different venders.
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Another comment suggested that the use of stainless steel balls 1n the ZHE
would Increase and Improve mixing. Thus, the extractor would simulate a ball
mi 11.
The Agency has no data indicating that mixing 1s a problem 1n the ZHE. The
Agency has evaluated the use of stainless steel balls for particle size
reduction, not necessarily for mixing. However, the steel balls resulted in
damage to the ZHE.
Many of the comments which were critical of the rotary agitator would like
the EPA to re-consider the agitation rate of 30 +/- 2 RPM. Several comments
questioned whether or not using the rotary tumbler at a fixed agitation rate of
30 +/- 2 RPM simulates actual landfill conditions. One comment criticized the
continuous agitation action, stating that continuous agitation during extraction
is an unnecessarily conservative condition. Another comment recommended that
the EPA reconsider the rotary tumbler for some wastes (I.e., dewatered sludge).
This comment asserted that more realistic results will be produced if vigorous
shaking is employed.
The Agency explains that continuous agitation is necessary in order to
ensure equilibrium between the extractant and the sample. Uniformity 1n mixing
of the sample and extractant is an Important factor 1n method precision. The
rotary tumbler apparatus is one of the most readily available and least
expensive methods of achieving the goal of effective mixing. Alternatives were
considered, including the use of stirrers as allowed in the EP, but they were
determined to be more costly and/or error prone. The agitation rate of 30 +/- 2
RPM ensures complete contact between the sample and the leaching medium.
C. Filters
Twenty five comments addressed the use of the borosilicate glass fiber
filter which has a pore size of 0.6-0.8 /tm. Only one of these comments provided
qualified support for the filter. The remaining comments were negative.
One comment believed that the filtering method has been improved. However,
the protocol should provide for changes of the glass fiber filter since the
filter tends to become plugged (even with careful application of gas pressure).
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The Agency agrees and states that, for the final filtration in the TCLP
(non-ZHE), the filters can be replaced. However, the ZHE cannot be opened to
replace filters. The Agency has modified the wording of the TCLP to reiterate
that centrlfugatlon may be used as an aid for filtration in the non-volatiles
procedure.
One comment expressed strong reservations about the EPA decision to change
the filter size in the TCLP. Specifically, it requested that the EPA explain
the basis for this change. If the filter is retained in the final rule, EPA
should explain how the change in filter size will improve testing accuracy.
The Agency refers to the March 10, 1986, TCLP Background Document (US EPA,
1986a) as the basis for using the borosllicate glass fiber filter. The decision
to change filter types was based on operational reasons: the glass fiber
filters do not clog as easily as the 0.45 /im membrane filters, and the Agency
believes that the glass fiber filters will provide a more adequate
differentiation between those materials which behave as liquids in the
environment and those which behave as solids 1n the subsurface environment.
The remaining comments addressed four specific areas of concern: filtering
oily waste; loss of Integrity of filter when wet; particulates 1n the filtrate;
and the availability of the specified filter.
Many comments expressed concern regarding the filtering of oily waste.
Several of these comments discussed the effect of dissolved and suspended oil in
the extract. One comment claimed that dissolved and suspended oil will be
recovered in the filtrate when filtering oily waste. This will yield a highly
biased recovery of components dissolved in the original oil, which does not
reflect the true mobility of these components. Another comment re-emphasized
the observation that the Increased pore size of the filter allows oil to pass
through and Into the filtrate.
The Agency 1s investigating waste-specific modifications to the TCLP. If
oily material passes freely through the filter, then it will be mobile and can
migrate to the ground water. In fact, dissolved and suspended oil has been
found 1n ground water 1n many areas. Therefore, there is no reason to exclude
oily liquids from the extract.
One comment stated that oily wastes plugged the filter within the first 15-
20 seconds of the filtration process. Another comment addressed the problems
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associated with filtering water Immiscible organlcs and other wastes.
Specifically, 1t stated that, even with a larger pore size, the immiscible
organic material will coat the filter fibers and produce a hydrophobic surface
that either Impedes or completely stops the filtration.
The Agency states that, if the method is followed with incremental increases
in pressure, the plugging problem will be minimized. To help the process of
filtration, centrlfugation may be used to facilitate the Initial liquid/solid
separation when the non-volatile procedure is used. However, if liquid remains
in the filtration unit, then for now it should be treated as a solid. The
Agency acknowledges that, when filtering difficult samples, problems will always
exist. Waste-specific modifications to the procedure are under investigation.
Another area of comment was the loss of integrity of the filter when it is
wet. Two comments criticized the filter on these grounds. According to one
comment, experience has shown that the loss of integrity makes it Impractical to
wash the filters prior to use. The TCLP should specify that the filters be
washed after the filtration device has been assembled.
The Agency states that the recommended filters, 1f handled carefully, will
not lose their integrity when wet. Acid washing after the filtration device has
been assembled is not recommended. The Agency believes that 1t 1s difficult to
remove all the acid from the filters and, as a result, may alter extract
concentrations (i. e., metal concentration).
Several other critical comments addressed the problem of particulates
passing through the filter Into the filtrate. According to these comments, the
glass fiber filter 1s likely to allow many more large particulates to pass
through the filter than the filter which was used 1n the EP did. One comment
suggested that the TCLP should allow for the clarification or removal of any
fine particulates which might pass through the less selective glass fiber
filters, and asserts that the TCLP should not Include the burdensome acid
digestion for metals analysis.
EPA believes that switching from the membrane filter to the glass fiber
filter will not increase significantly the passage of particulates into the
extract, and that particles which pass through the filter will also be mobile in
the subsurface environment. The Agency notes that acid digestion has always
been required for the EP, and will continue to be required for the TCLP.
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One comment stated that the EPRI-commissioned "round-robin" study shows that
metal contamination, 1n conjunction with the glass fiber filter, is high (even
when the filter is washed with acid as described 1n the TCLP proposal). This
corranent recorranended washing the glass fiber filter with at least 1.5 liters of
the acid solution, to be followed by rinsing with two liters of de-ionized
distilled water. The commenter believed that this rinsing will provide a
satisfactory means of removing contamination in the glass fiber filter.
The Agency states that the EPRI study revealed that only one laboratory
showed a problem while using the glass fiber filters and this was traced to
contaminated dilution water (EPRI, 1986). Also, step 4.4 of the TCLP method
provides an adequate acid washing procedure.
Three comments objecting to the use of the specified filter addressed the
unavailability of the necessary size of glass fiber filter. One comment stated
that the specified size of the filter holder is 142 mm. However, the only
acceptable filter is the Whatman GFF which is not available in the 142 mm size.
EPA acknowledges the fact that the Whatman 142 mm glass fiber filters are
not readily available; however, Whatman's 150 mm filters can be readily adapted
for use.
D. Reagents
Four comments addressed reagents used in the TCLP. The areas of interest
included the daily preparation of the extraction fluid, reagent grade glacial
acetic acid, adjusting the buffering solutions, and storage for ASTM type 1
water.
Three comments addressed the requirement that the extraction fluid be
prepared on a dally basis. One comment questioned why the extraction fluid must
be prepared dally 1f the pH of each of the extraction fluids is to be evaluated
before use and if there is one blank for every 10 extractions. Furthermore, if
the pH of the leaching fluids meet the criteria and the method blanks are free
of contamination, then 1t may be more cost effective to prepare a large supply
of the leaching fluid rather than preparing a small volume on a daily basis.
Another comment stated that the Agency has presented no rationale for the
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requirement which states that the leaching reagents must be prepared on a daily
basis. This comment also stated that the proposed requirement imposes
unnecessarily harsh conditions on the laboratories.
The Agency notes that the daily preparation of the extraction fluid 1s now
suggested rather than required. (See Note at 5.6.2.) Experience has shown that
short term deterioration of the extraction fluid is not a problem.
One comment responded specifically to the wording contained in step 5.5. It
pointed out that the phrase "made from" in step 5.5 should be replaced with a
semicolon or a colon. This change will clarify the fact that glacial acetic
acid may be purchased as a reagent grade. It is not prepared that way in the
laboratory.
The Agency agrees and the TCLP method modifications have changed the wording
of step 5.5 to read glacial acetic acid is ACS grade and not prepared from ACS
grade.
One comment expressed some confusion regarding the preparation of reagents
to be used 1n the TCLP and recommended that specific directions be given for the
adjustment of buffering solutions. It also suggested that the ASTM Type 1 water
used in the analysis of volatiles be stored under inert gas or with ho headspace
to minimize contamination.
In response, the Agency states that specific directions are not necessary
since buffering solutions are not adjusted. If the buffering solutions are
prepared according to the directions, adjustment will not be necessary. The
Agency refers to the TCLP method changes and states that the TCLP will require
Reagent Water instead of ASTM Type 1 water. (See Step 5.1.)
E. Leaching Media and Liquid/Solid Ratio
Thirty-four comments criticized the dual leaching media composition. One
comment expressed concern over the effects of the sodium acetate buffer on
specific wastes. For example, the use of the buffered extraction fluid in the
TCLP appears to be designed for the extraction of volatile compounds in the ZHE
device. Since alkaline wastes will not be neutralized by the extraction fluid
or adjusted to a specific pH, the leaching of wastes for extractable organics
and metals could be compromised. The use of distilled or ASTM Type 1 deionized
41
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water should be given consideration so that interferences, artifacts, and
possible contamination could be minimized.
In response, EPA states that the buffered solution was chosen from ORNL
research on both organic and inorganic wastes using the conventional bottle
extractor. A more acidic leaching solution is required for alkaline wastes.
Research has shown that leaching medium composition is more important for the
leaching of metals than for the leaching of organics (Warner et al., 1981). EPA
is investigating the use of distilled water for the extraction of volatiles.
Eleven comments addressed the effects of the acetic acid solution on
alkaline wastes, natural buffering wastes, and mining wastes. Specifically, one
comment stated that EPA's assertion that the TCLP and EP values should be
approximately the same for sludges is not true for some weak to moderate
alkaline wastes. Therefore, the TCLP should be modified to avoid undue over-
regulating of EP nonhazardous wastes with weak to moderate alkalinity.
Several comments were concerned that the acetic acid solution is overly
aggressive and will result in more wastes being regulated as hazardous.
Specifically, one comment stated that the extraction fluid #2 1s equivalent to
the maximum amount of acid added under the current EP method. The criteria for
selecting the extraction fluid will increase the number of wastes subject to the
extraction procedure with the maximum amount of acid. Similarly, those wastes
requiring very little acid to maintain pH 5.0 by the EP will be subject to
extraction under more addle conditions with extraction fluid #1 by the TCLP.
One comment expressed concern over alkaline or chemically-treated wastes.
This comment stated that the stronger acid leach media will tend to destroy the
stability of alkaline or chemically-treated waste. Another comment discussed
the destabilizing effects of acetic acid on buffering wastes. This comment
stated that the acetic acid solution penalizes wastes that have natural
buffering capacity.
Several comments were concerned that the acetic acid solution will result in
an unrepresentative and excessively high concentration of metals. One comment
pointed out that acetic acid causes a greater amount of leaching of metals from
a solidified mass than what occurs in nature. Acetic acid is not commonly found
in nature in the concentrations used either in the EP toxicity test or the new
TCLP test. Another comment stated that an acetic acid solution will
42
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overestimate (by up to several orders of magnitude) the amount of metals which
could leach from the waste. Similarly, one comment stated that the change In
extraction fluid could have a major Impact on the solubility of metals during
the TCLP. Therefore, a single extraction fluid (#1) should be applied to all
wastes, regardless of pH, to avoid complicating steps and to establish a common
set of operating conditions.
Two comments addressed the use of an acetic acid solution with mining
wastes. These comments provided extensive discussions regarding the impact of
using an acetic acid-acetate solution for mining wastes. The comments argued
that these wastes are placed in monofill disposal sites and are not exposed to
organic acids, which are extremely aggressive in solubilizing certain metals.
The Agency points out that the Oak Ridge studies show the acetate buffer
leaching medium produces contaminant concentrations comparable to those observed
in the field lysimeter leachate (Francis et al., 1984; Francis and Maskarlnec,
1986). Comparisons of the TCLP with the EP conducted by the Electric Power
Research Institute (EPRI, 1986) and a group of trade associations (Lancy, 1986)
Indicate no significant difference in the metals concentrations obtained using
the two tests. The Agency recognizes that the TCLP was not designed for site-
specific evaluations and is currently investigating other approaches to testing,
including alternatives for regulating monofill disposal.
Several comments questioned the validity of the 20:1 extraction ratio. One
comment requested that the EPA justify the selection of the 20:1 extraction
ratio. Another comment pointed out that the ratio of 20:1 does not yield a
concentration representative of an Infinitely long extraction process. This
comment also stated that the literature Indicates that ratios closer to 10:1 in
batch extractions represent more accurately the equilibrium values found in
continuous flow column extractions. Therefore, the 20:1 ratio underestimates
the concentration 1n the Initial pulse of leachate from the site but over-
estimates the long-term equilibrium release. Another comment also questioned
whether or not the 20:1 extraction ratio actually represents the effect of
leaching in the disposal environment.
The Agency responds that the 20:1 ratio of leaching fluid to waste
represents a reasonable compromise to approximate the average maximum exposure
concentration. Since this regulation is primarily concerned with the chronic
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toxicity of compounds over medium to long exposure Intervals, the 20:1 ratio is
more appropriate than a lower ratio such as 10:1 or 4:1. The Agency
acknowledges that the 20:1 ratio is based on practical as well as theoretical
considerations. Research shows that a liquid to solid ratio less than 20:1
gives results that are less reproducible, while higher ratios present practical
problems because of the volume of material to be handled. (Klmmel and Friedman,
1984).
Some of the comments which criticized the dual leaching media composition
expressed concern regarding the pH requirement of the extracting fluid. One
comment pointed out that the leaching media create acidic conditions which are
much more exaggerated than those found 1n even the most conservative municipal
landfill mismanagement scenario. Another comment recommended a neutral medium
as an alternative to the acidic leaching medium.
The Agency repeats that the acetate buffer leaching fluid adequately
reproduced the contaminant concentration obtained from the field lysimeterS, as
shown in the Oak Ridge research (US EPA, 1986a; Francis et al., 1984). The
acetic acid leaching fluid contains the maximum amount of acid allowed for the
EP test. Both natural rainwater and municipal landfill leachate tend to be
acidic rather than neutral.
Two comments questioned the validity of using two leaching media. One
comment asked if the TCLP is intended to represent a worst-case co-disposal
scenario, what is the need for two different extracting solutions for wastes
with different pH values. This comment stated that the pH of the leachate will
not become more acidic if the landfill contains a basic waste. Several other
*
comments also supported the use of a single extraction fluid. One stated that,
if the EPA is predicting that a waste will be contacted by 200 milliequivalents
of acid per 100 grams of sample, then that amount of acid should be used in all
cases. According to another comment, the EPA should use only one type of
leaching fluid for the TCLP since municipal refuse constitutes 95% of the waste
present in the landfill and has the greatest impact on leachate composition.
The comment goes on to say that EPA's study has shown that leachate which is
generated by decomposing municipal waste contains approximately 0.14 equivalents
of acidity per kilogram of dry refuse. When disposed of as a non-hazardous
waste at a municipal landfill, the industrial waste tested under the TCLP will
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have, at the most, a minimal effect on the quality of the landfill leachate.
Since the acidity of munlcioal landfill leachates 1s Influenced primarily by the
municipal refuse (not by the industrial wastes), the acidity of the leaching
fluid should be 0,7 milHequivalent per gram of waste, as established by the Oak
Ridge studies.
The Agency points out that in order for all wastes to be exposed to a
leaching medium of the same pH, more acid must be added to wastes of high
alkalinity. The quantity of acid used (2 milliequivalents of acid per gram of
waste) is based on data collected by EPA at a municipal landfill over a period
of years (US EPA, 1980). The Agency believes that, over time, the buffering
capacity of alkaline wastes will be exhausted, and in order to accurately
predict the leaching potential of such wastes a more acidic leaching medium must
be employed. The EP test requires titration of the waste until a constant pH is
reached or the maximum amount of acid is used. The TCLP requires the same
maximum amount of acid for highly alkaline wastes.
One comment stated that the specified pH of 4.93 +/- 0.05 1s overly precise.
The +/- 0.2 pH units of the EP should prove adequate especially for organic
compounds. If the pH is maintained at +/- 0.05 pH units, an option to adjust
the final pH (by adding more acid or base) should be included 1n the procedure.
Another comment stated that the pH requirement of the extraction fluid at +/-
0.05 pH units is stringent and unjustified.
The Agency asserts that, 1n the EP, the pH is measured 1n a dynamic system.
Therefore, the pH measurement 1s maintained in a less precise fashion. In the
TCLP, the pH of the extraction fluid is measured prior to contact with the
waste. Adjusting the final pH should be unnecessary if the fluid is properly
prepared and may cause fluctuations in the buffering capacity of the extraction
fluid. The'Agency believes that the requirement (in Section 5.6.1) of
maintaining the pH of the extraction fluid at +/- 0.05 pH units is necessary to
ensure reproducible results.
A comment was received concerning the pH of extraction fluid # 2. This
comment stated that the extraction fluid should have a pH of 2.88 +/- 0.05 and
questioned what should be done if it does not meet this pH requirement.
The Agency urges that the method be reviewed and that the extraction fluid
be prepared again. If the fluid is prepared correctly, pH adjustment should not
be necessary.
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Another conment addressed the Impact of the acetate buffer on subsequent
biological testing. Using the acetate buffer will severely hinder the use of an
integrating technique such as biological tests. This shortcoming will become
more apparent as additional compounds are added to the regulated list.
Therefore, EPA should study how to make the TCLP fluids compatible with these
tests.
The Agency notes that no biological toxicity tests are currently used in the
RCRA regulatory program. Although producing a leachate compatible with
biological testing was an original objective in developing the test, the lack of
such compatibility is not a serious drawback to the current regulatory program.
Several comments addressed the application of the TCLP to a variety of
settings. One comment suggested that the EPA allow more appropriate extractants
to be used in specific applications. This would avoid applying the TCLP to
something other than its originally intended purpose. Another comment suggested
that the TCLP be modified by allowing different leaching media for different
uses of the TCLP. (i.e., use of distilled water extraction for purely
industrial waste land disposal units).
The Agency responds that waste and disposal specific alternatives are
currently being investigated.
F. Particle Size Reduction
Fifty-one comments addressed the particle size reduction requirement. Two
comments provided qualified support for this requirement while the rest were
critical. Areas of criticism include particle size reduction requirements for
monolithic wastes and the effect of the particle size reduction requirements on
volatiles.
Numerous comments supported the re-instatement of the structural integrity
procedure or some reasonable stability criterion. One coirenent pointed out that
particle size reduction will be inappropriate in those Instances where
solidification of the waste is used as a treatment technique. The assumption
that heavy machinery will break up the waste 1n a municipal landfill has never
been shown to be realistic for hazardous waste management facilities. The
environment inside the landfill cell (after the daily cover has been applied)
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would be relatively constant. This comment also stated that the structural
integrity test should be retained to evaluate stabilized waste. Another comment
questioned whether or not grinding represents adequately the weathering process
or the vehicular traffic. It recommended that the Agency retain the SIP.
Two comments suggested improving the structural integrity test. One of
these disagreed with EPA's requirement for particle size reduction and disputes
the assumption that natural weathering forces are an important mechanism for
breaking down monolithic wastes. This comment stated that particle size
reduction could lead to a loss of volatiles or unrealistically increase the
leaching rates of less volatile components. It recommended that EPA look into
improving the SIP. Another comment suggested that the SIP could be improved by
incorporating a compression test, a freeze/thaw test, and possibly some
allowances for surface area.
Many comments agreed that particle size reduction is inappropriate for
stabilized monolithic wastes and produces unrepresentative results. For
example, one comment stated that particle size reduction alters the physical
character of many wastes 1n such a way that the leaching rate Increases
unrealistically. This comment stated that particle size reduction destroys the
cementitious property of these wastes. By Increasing greatly the surface area
which is available to attack by a leaching medium, the amount and rate at which
substances may be leached are increased unrealistically. In as much as waste
grinding is not normally employed in municipal landfills, particle size
reduction renders the TCLP a less accurate model for leaching 1n a municipal
landfill environment.
The Agency refers the commenters to the proposal 1n the May 24, 1988,
Federal Register (53 FR 18792-18797) to use a stainless steel cage in the bottle
extractor Instead of requiring particle size reduction for the analysis of
wastes for non-volatile contaminants. This proposal and comments received in
response are discussed in more detail in Section VI of this Background Document.
Several comments suggested a standardized particle size requirement for all
waste forms. Specifically, one comment recommended that the Agency incorporate
particle size and surface area measurements in the protocol. Then extract
concentration values should be correlated with surface area whenever comparison
between waste forms are made. Another comment recommended that the size
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reduction requirement be revised to require a particle size which reflects a 20
to 30 ps1 unconflned compressive strength. According to one comment, a
standardized size reduction methodology should be developed that would be used
for all materials requiring size reduction.
The Agency notes that waste forms vary so widely that it would be
impractical to specify a standardized size reduction procedure.
One comment stated that a minimum particle size should be specified in order
to ensure uniform test results.
The Agency responds that natural or artificial particle size reduction will
result in various particle sizes, and it is impractical to specify a minimum
size.
Several comments which criticized particle size reduction were concerned
with the effect of the requirements on volatiles. They suggested that a loss of
volatiles will occur as a result of particle size reduction. One comment
asserted that all reduction equipment will generate some heat, while another
comment asserts that the grinding and milling equipment required for particle
size reduction will result in a loss of volatiles. Another comment suggested
that the loss can be substantially reduced if the sample 1s frozen in liquid
nitrogen prior to particle size reduction.
The Agency states that it is currently considering alternatives for
minimizing the loss of volatiles. However, the particle size reduction
requirement will remain for volatile contaminants until additional data are
obtained and evaluated. Particle size reduction 1s necessary to ensure contact
between the leaching fluid and the waste.
Another comment stated that the Agency should allow demonstrated physical'
stabilization (I.e., irreversible binding to soil matrix) to be a legitimate *
mechanism for the environmental unavailability of contaminants.
The Agency states that if irreversible binding to soil particles occurs, the
contaminants will not be found in the TCLP leachate.
G. Procedure when Non-Volatiles are Involved
Eighty-two comments addressed issues related to the TCLP procedure for non-
volatiles. Areas of concern included the sample size requirements, the
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filtration steps (liquid/solid separation), determination of percent solids,
particle size evaluation and reduction, the alkalinity test, the extraction
fluid, the filtration of the extract, the TCLP extract preparation, and the TCLP
extract analysis.
Sample Size Requirements (7.1 - 7.5)
Several comments stated that different amounts of leachate are required,
depending on the analytical technique and the number of different analyses to be
performed. Consequently, the actual sample size needed (not necessarily 100 g)
will vary, according to the analyses which are performed. A trade organization
noted that its experience with SW-846 methods for semi-volatiles, metals,
pesticides, and herbicides has shown that a total of 4 liters are necessary for
a complete suite of analyses. Another trade association suggested that it is
improbable that a single extraction will yield enough leachate to determine all
constituents. Many of the analytical methods for organics and pesticides
require a liter of aqueous solution for each analysis. This will require
multiple extractions and the combination of multi-liter volumes of leachate
prior to analysis. Costs will increase 1n direct proportion to the number of
extractions required to generate sufficient leachate.
The Agency recommends that, if one extraction will not generate sufficient
leachate to perform these analyses, multiple extractions should be performed
with the leachate from all of them combined and allquoted for analysis. The
cost will vary depending on the type of waste and the analyses required. Few
wastes will require analysis for the entire list of contaminants. Process
knowledge and preliminary constituent analysis (pre-screen test) can be used to
determine which contaminants are likely to be present in a given waste.
Several comments' expressed confusion regarding the sample size required for
the procedure. They suggested different requirements for the sample size, based
on the percent of sol Ids 1n the sample. These comments suggested that the
required solid phase sample size (75 g) is unreasonable for wastes with low
percentage solids. Some comments pointed out that a waste with 1% solids would
require a 7.5 kg sample and a waste with 0.5% solids would require a 15 kg
sample to obtain the required sample size. A manufacturer suggested reducing
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the required solid phase sample size to 25g in order to reduce the volume of the
original sample taken for analysis. A research lab pointed out that the
required sample size of lOOg yields 2 liters of leachate. However, the volume
of the specified filtration vessel reservoir is only 1.5 liters. They
recommended either decreasing the required sample size to 75g or modifying the
filtration apparatus to accommodate the 2 liter volume. A manufacturer noted
that the 75g requirement is unnecessary if a small volume of extract would
support the analyses. It recommended that the wording be changed to state that
enough solids must be generated for extraction to support analyses.
The Agency agrees with the last commenter and has changed the method
requirements to indicate that enough solids must be generated for extraction
such that the volume of extract will be sufficient to perform the required
analyses. The method recommends a minimum of 75g of solids 1f the full range of
analyses is required. In most cases, the extract will not need to be analyzed
for the entire list of contaminants.
Filtration Steps - Liquid/Solid Separation (7.7)
Some of the comments in this section addressed the failure of the TCIP to
provide directions as to how fluids from centrifugation are to be treated. One
comment questioned whether these fluids should be discarded or combined with the
fluid expressed from the wastes in step 7.9. If the latter 1s correct, they
suggested that section 7.16 be expanded to include an equation that includes the
amount of waste originally centrifuged, volume of fluid obtained by
centrifugation, amount of waste charged to the extractor as a percentage of the
waste originally centrifuged, and the amount of centrifuged liquid analyzed
(separately or combined) as a percentage of the total fluid obtained. An oil
company believed that centrifugation should be allowed as a laboratory technique
for separating and evaluating wastes when volatile compounds are not of concern.
Centrifugation would eliminate problems such as filter plugging and help to
achieve acceptable separations.
The Agency agrees that clarification of the method is required regarding the
use of centrifugation. The method now states that centrifugation is to be used
only as an aid to filtration and only when non-volatiles are the analytes of
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concern. Following centrifugatlon, the liquid should be decanted and filtered,
followed by filtration of the solid through the same filter system. The
Instructions have been moved to the front of the method for non-volat1les. (See
Step 8.6)
Another trade association suggested that, to remain consistent with the
original design of the EP where particles greater than 0.45 um were excluded,
the TCLP should allow for the clarification or removal of fine particulates
which might pass through the less selective glass fiber filters. It suggested
using 0.45 um membrane filters as in the EP. Including these fine particles
adds the extra burdensome step (as described 1n step 7.16) of acid digestion
when analyzing for metals. This acid digestion of particulates would yield an
obvious increase in metals concentration if metals were indeed present in the
solid waste and is not representative of the leached concentration of metals.
The Agency believes that particles which pass through the filter may also
migrate with the leachate. Release of metals from ligands is critical and the
acid digestion of the leachate prior to analysis 1s necessary 1n order to
accomplish this.
A few comments addressed the actual filtration step Itself and how the
decision to stop applying pressure should be made. One manufacturer recommends
that the filtration step which specifies that the filtration pressure should be
increased until "no additional liquid has passed through the filter in any 2
minute Interval" be clarified. Also, replacing the phrase "no additional
liquid" with a relative volume such as 1% would eliminate further confusion. A
contract laboratory requested further clarification of the directions which
state that "no fluid 1s obtained under pressurization."
EPA believes 1t will make little difference whether "no additional liquid"
or "1% 1n a two minute Interval" 1s specified (to define the termination of
filtration). However, 1t should be easier to detect the cessation of flow
rather than to quantify continuing flow. Therefore, the Instruction 1n the
method has not been changed.
Other comments refered to transferring the sample from the shipping
container to the filtration device and suggest a way of diminishing sample loss.
A trade association claimed that problems with the adherence of waste to the
walls of the container can be avoided if the waste 1s transferred directly from
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the waste shipping container Into the filter holder. The amount of waste
charged 1s equal to the weight of the original container minus its weight after
the waste is transferred. Two manufacturers stated that clarification 1s needed
regarding when a correction to the original sample weight should be made. Such
a correction could change the solid to liquid ratio and consequently have an
impact on the characterization of the waste. They recommended that the existing
correction note be replaced with an emphasis on the quantitative transference of
sample to filtration device.
The Agency has changed the method directions to emphasize a quantitative
transfer of solids. The note states that, if any solid (> 1%) has adhered to
the filter holder, the person conducting the test should determine the weight of
this solid and subtract this weight from the amount of solid in the filtration
device before transfer. (See Note at Step 8.7)
Another trade association comment stated that acid and distilled water
filter rinsing (as required in step 4.4 for filters used in preparation for
metal analyses) should be expanded and allowed when evaluating the mobility of
all non-volatiles.
The Agency states that its ruggedness study does not indicate a need for
cleaning filters for non-metallic samples. However, the method does not
prohibit acid and water rinsed filters for all non-volatile analyses.
A municipality stated that more than one filter should be allowed in step
7.7 to lessen the likelihood of rupture and degradation of the glass fiber
filter (possibly caused by instantaneous application of high pressure).
The Agency has added a second note 1n Step 8.7 (formerly 7.7) indicating
that pressure should be increased gradually to minimize the likelihood of
rupturing the filter.
One commenter was concerned that the instructions 1n step 7.7 imply that
vacuum and pressure filtration are equivalent. The instructions should specify
that pressure filtration 1s necessary unless air moves through the filter at 10
psi.
The Agency agrees. Vacuum filtration is recommended only for waste with low
solids content (<10%) or for highly granular waste. See Step 4.3.2.
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Determination of Percent Solids (7.9 - 7.10)
One comment suggested an Increase in the percent sol Ids required to discard
the solid portion from 0.5% to higher levels, e.g. 1%. Several comments
recommended removing this portion of the procedure altogether for reasons
discussed below. A state agency noted that the EPA criterion for performing an
extraction is the weight of residue which is collected on a filter disc when 100
ml of sample 1s filtered. If the weight of the residue is less than 0.5 g, the
filtrate 1s used as the extract for elemental or compound analysis. The comment
expressed disagreement with the cutoff amount of 0.5 g and believes it should be
increased to at least 10 g. The comment suggested that a better evaluation of
mostly liquid samples would consist of pouring off the liquid, weighing 100 g of
solid sample, re-combining the liquid portion of the sample, adding the
extraction fluid, and performing the TCLP extraction procedure.
A municipality suggested that, instead of filtering the original waste, one
could calculate the amount of leaching solution to add to the original waste.
The amount added by weight would be 20 times the weight of the bone dry solids
in the sample. In this simplified, one time filtration procedure, the ratio of
leaching fluid volume to total solids would be less than or equal to that ratio
in the procedures as written. This method would provide for a worst case
situation and expedite matters especially where volatiles are concerned.
Another municipality pointed out that, in the test procedure (step 7.10.4),
wastes with less than 0.5% solids are filtered. The liquid phase is then used
as the TCLP extract. For wastes with more than 0.5% solids, the solid phase of
the waste is diluted 20:1. The comment suggested that since liquid wastes are
also diluted and attenuated in the environment, liquid wastes (less than 0.5%
solids) should also be subjected to the 20:1 dilution factor. A federal lab
also suggested that the pre-extract1on separation procedure be dropped and the
entire original sample extracted at a 20:1 ratio. This would help eliminate the
loss of volatiles and facilitate only one extraction for all concerned
constituents.
A chemical company stated that the initial solid/liquid separation adds an
unnecessary step to the entire TCLP. This step creates some manipulative
problems with the arbitrary classification of wastes based on 0.5% solids
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content. It suggests that the test consist of simply mixing 25 g of sample Into
500 ml of extract solvent, contacting for the desired time, filtering off enough
liquid for analysis, and proceeding with the GC/MS test. Including the less
than 0.5% solids for extraction is of no consequence while eliminating steps 7.9
through 7.10 will save significant amount of time and money.
The Agency responds that the sol id/11 quid separation has been shown
important in the extraction of metals and semi-volatlles. The Agency is
investigating the elimination of the solid/liquid separation step for volatiles.
Several comments suggested that a precautionary note be added which states
that the drying oven should be vented to a hood or other appropriate device.
They noted that an explosion may occur when certain types of organic materials
(i.e., polynitro aromatics) are taken to dryness.
The Agency has had no reports of explosions, but agrees that a cautionary
note is 1n order and has added one to the procedure. (See Note at Step 7.2.2.)
A commercial laboratory pointed out that in the TCLP procedure there are
four different methods for determining percent sol Ids. By using the TCLP
procedure, a different percent sol Ids would probably be obtained on the same
sample when extracted for both volatile and non-volatile components. It
recommends that a single method for determining percent sol Ids be required. The
piston-pressure filtration would be a good choice for this. However, that
method would require that all labs possess a ZHE, even 1f they only analyze for
non-volatile components. Therefore, 1n order to eliminate unnecessary costs
(i.e., purchase of ZHE), they recommended use of the vacuum filtration method.
The Agency has re-written the method instructions regarding determination of
percent solids. This procedure only must be performed once, and the results may
be used for the determination of both volatile and non-volatile analytes. (See
Section 7.1) Non-ZHE pressure filtration devices are available, and such
devices are recommended for wastes with greater than 10% solids unless they are
highly granular. (See Section 4.3.2)
A state"agency noted that no provision 1s made for samples containing
exactly 0.5% sol Ids. They recommended that the wording be changed to "for waste
containing 0.5% solids or greater."
EPA notes that step 2.2 has been changed to indicate greater than or equal
to 0.5% solids.
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A trade association stated that sol Ids should be determined on a "dry"
basis. As written, the test would allow varying degrees of moisture in the
solid portion of the waste. This would result in varying degrees of active
ingredients 1n the waste samples that are subject to the actual extraction.
This will create inconsistent analytical results among different laboratories.
The Agency replies that the method is based on an extraction of a sample of
the waste that 1s not filterable under the conditions of the test. It is not
meant to extract "dry" solids only, since wastes are not landfilled in a "dry"
condition. The portion of the waste which will not pass a 0.6 - 0.8 um filter
under 50 psi is assumed to correspond to the waste in the landfill which will be
subject to leaching.
Particle Size Evaluation/Reduction (7.11)
Two comments received regarding particle size evaluation/reduction asserted
that particle size reduction should be accomplished prior to step 7.5 (to avoid
sample loss during the grinding step). They noted that moist material will
adhere to the particle size reduction equipment. Such a loss will be impossible
to measure.
EPA agrees with these comments and has made this change. It is believed
that this will result 1n a smaller loss of analytes and 1n a maximization of
sample homogeneity 1n the procedure. (See Step 6.2)
Another comment stated that procedures for particle size reduction and
surface area measurement must be specified 1n order to assure equivalent results
among analysts and among laboratories.
The Agency responds that any particle size reduction technique will result
in various sizes of particles. Therefore, a common technique will not
necessarily provide reproducible results. Also, materials which require
particle size reduction (i.e. cement blocks, telephone poles, steel beams, etc.)
t
vary so much that 1t would not be practical to specify a single'technique.
Alkalinity Test (7.12)
Two comments suggested that the size of the subsample used for the
alkalinity test (step 7.12.1) (on a dry weight basis) be specified. The amount
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of acid added 1n step 7.12.3 is 3.5 milUmoles. This 1s equal to 140 mg of
NaOH. Therefore, if the subsample is small enough, all wastes will be
determined to require extraction fluid #1. The comments suggested that the only
way to avoid this problem is to decide on a total alkalinity cutoff value for
the waste solution generated 1n step 7.12.1. This will increase the amount of
time and money required to perform the TCLP.
The Agency replies that the method specifies a 5.0 gram sample of the solid
phase of the waste be used for the alkalinity determination. The solid phase is
that portion which will not pass a 0.6 - 0.8 um glass fiber filter under a
pressure of 50 psi. The quantity of acid required is 3.5 mL of IN HC1, or 3.5
millimoles. (See Step 7.4)
A manufacturer believed that requiring particle size reduction to 1 mm for
the alkalinity test is contradictory since step 7.11 requires a reduction to
only 9.5 mm. The comment also questions the justification for including Steps
5.5.1 and 7.12.1 through 7.12.4. The comment asked for clarification regarding
how the specific volumes, weights, time, temperatures, and normalities were
determined and recommended that Step 2.0 (the method summary) include some
explanation of the above mentioned steps.
The Agency responds that the 1 mm particle size 1s designed to demonstrate
quickly and easily the buffering capacity of the waste and to ensure that the
5 g aliquot is as representative as possible. Additional information is
provided in ERC0, 1986, and USEPA, 1986a.
Extraction Time (7.13)
Several comments discussed the requirement of an 18-hour extraction time." A
chemicals and metals processing firm supported the reduction in extraction time
from 24 hours (for the EP) to 18 hours (for the TCLP). Several trade
associations believed an 18-hour extraction time creates problems 1n scheduling
laboratory work. They suggested that some tolerance interval be allowed. One
comment stated that this time period restricts a typical laboratory to beginning
the test in the afternoon and completing it the next morning. This would result
in potentially unnecessary logistical problems and labor costs. Maintaining the
24-hour (plus or minus four hours) extraction period would coincide more readily
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with a typical work schedule. Another asserts that unless EPA has data showing
that the exact length of agitation period Is critical, the required agitation
period should Include a tolerance Interval (i.e., 18 +/- 2 hours). This comment
also requests an explanation of the basis for choosing 18 hours as an agitation
period.
The Agency agrees with the comments regarding extraction time. It has
changed the method to read 18 +/- 2 hours, based on the ruggedness testing. The
Agency does not believe that the 18 hour extraction time disrupts work schedules
more than the 24 hour extraction period does. Discussions of the effects of
changes in the time of agitation can be found 1n US EPA, 1986a, and Brown et
al., 1983.
Filtration of Extract (7.14)
Several comments stated that the directions for the re-comb1nation of the
filtered extract and the filtrate from the Initial Hqu1d/sol1d separation do
not consider the reduction in the amount of solid extracted due to performance
of the alkalinity test and any adherence of solids to the wall of the filtration
vessel. The comments pointed out that the volume of initial filtrate should be
reduced proportional to the loss of solids.
The Agency replies that the alkalinity test is now performed on a separate
sample of the waste, and emphasis 1s placed on the quantitative transfer of
solids from the filtration device to the extraction vessel. Adjusting the
volume of the initial filtrate to account for loss of solids would further
complicate the method with a negligible impact on results.
A research laboratory suggested that, following extraction of the solid
waste and filtration of the leachate, a preservation step should be added
(instead of referencing a procedure in SW-846). It recommended that a table be
made which clearly states the preferred method of preservation and holding times
for each measured parameter.
EPA has changed the method to specify that aliquots of leachate for metals
analysis be acidified to pH 2 with Nitric Acid as soon as possible. Other non-
volatile and volatile samples should be refrigerated at 4*C until analyzed. See
Step 8.14. Holding times prior to analysis are addressed in Step 10.6.
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A trade association questioned whether or not it is necessary to filter the
extract if a non-filtered extract passes the test.
The Agency agrees that a non-filtered extract will probably contain higher
concentrations of analytes than a filtered extract. Analyzing unfiltered
extract is not part of the method. A pre-screen test, consisting of a total
waste analysis, has been included as part of the method for persons who want to
demonstrate that the waste itself does not contain hazardous levels of the
regulated constituents.
One comment stated that filtration presents a real problem for tars, viscous
polymer wastes, and still bottoms that are fluid only at high temperatures.
The Agency agrees that these materials do offer special analytical
difficulties, whatever approach is taken. It is likely that the TCLP would
treat these samples as 100% solids. The behavior of difficult to filter wastes
in the TCLP is currently being investigated.
TCLP Extract Preparation (7.16)
Some comments stated that the volume of initial fluid expressed from the
waste may be insufficient for analysis by SW-846 methods. If this 1s the case,
the comments questioned whether the fluid may be diluted to a volume sufficient
to meet the analytical requirements or how the fluid must be analyzed.
The Agency responds that if insufficient leachate is obtained, the procedure
may be repeated until enough liquid is available to perform the analyses. In
some cases, large quantities of sample and multiple extractions may be required.
Dilution of the leachate 1s not permitted, because dilution may reduce the
concentration of contaminant 1n the fluid being analyzed to a level below the'
limit of quantitation of the analytical procedure.
A state agency noted that Part 3.0 refers to analytical interferences.
However, there is no mention made of potential interferences with the leaching
procedure itself. The writer suggested that possible acid-base reactions, gas
evolution, and problems with oily waste should be discussed 1n Section 7.0.
The Agency does not consider acid base reactions, gas evolution, or oily
waste to be interferences in the procedure. Notes on how to handle such
occurrences can be found in sections 8.8, 8.11, and 9.10.
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A trade association questioned whether or not the acidity (pH) of a leachate
should have a "limiting value. It suggested that a, waste which generates a low
pH leachate would seem undesirable 1n Itself.
EPA's corrosivity characteristic addresses wastes with extreme pH values.
TCLP Extract Analysis (7.16)
A number of comments discussed analytical procedure issues. A trade
association noted that Method 8280 for dioxin analysis was mentioned in the
January 14, 1986, proposal as being part of SW-846. However, it has never been
included in the SW-846 manual. A metals processing firm recommended that other
analytical procedures which are equally valid be approved as alternatives. It
also recommended that the decision of which method to use be left to trained
analytical chemists. A chemical company believed that the high variability of
analytical methods is a matter of concern. Since the precision of the TCLP is
affected by both the extraction procedure and the analytical methods, the
variability of the TCLP would raise some questions in the use of the procedure
for enforcement purposes.
The Agency notes that, where alternative methods are available within SW-
846, the analyst has the option of selecting among these for compliance with the
requirements of the Toxicity Characteristic. Method 8280 is included in the
Third Edition of SW-846. In addition, data on alternative methods can be
supplied to EPA for possible Inclusion 1n future editions of SW-846. EPA
believes that the variability of the method can be reduced by multiple
extractions and compositing of extracts prior to aliquoting for analysis.
Multiple sub-sampling will reduce the variability 1n the TCLP.
Several comments voiced concern about the analysis of TCLP extracts for
metals. A trade association stated that, if leaching metals are of prime
concern, acid digestion 1s not needed for most atomic absorption
spectrophotometry analyses. If release of metals from Hgands for analysis is
deemed critical, then the comment recommended that the acid and the conditions
of digestion be specified. A state agency recommended that the directions be
changed to read "TCLP extracts to be analyzed for metals other than mercury be
acid digested" because no acid digestion is involved in the analysis of mercury.
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EPA replies that acid digestion is needed for the TCLP prior to analysis for
metals other than mercury. The metal content of particles and release of metals
from ligands 1s critical. The third edition of SW-846 gives explicit
instructions on necessary procedures. Mercury, however, need not be acid
digested, and the method has been changed accordingly. (See Step 8.14)
One waste management firm claimed that if extremely small particles pass
through the filter and the filtrate (with the small particles) is subjected to a
flame method of analysis, the particle concentrations (as well as the leachate
concentrations) will be detected. The TCLP is supposed to analyze the leachate
alone, not falsely determine solid concentrations due to the inadequacies of the
procedure.
The Agency responds that the method is intended to measure metals which are
mobile in the environment. Particles which pass through the filter are assumed
to migrate with the liquid 1n the subsurface and pose a potential threat to
ground water.
Another trade association believed that a compatibility test must be
described. The formation of a precipitate should not prohibit combining liquid
phases in order to determine inorganics. The subsequent SW-846 analytical
procedures require digestion prior to analysis, thus making the formation of a
precipitate irrelevant.
EPA replies that "compatibility" for the purpose of this test includes
immiscibi1ity as well as formation of precipitate. No test for compatibility
will be described, because a visual determination will be sufficient 1n most
cases. The method has been changed to state that, for Inorganic analysis, if a
*
precipitate forms upon combination of the liquid phases, this does not
constitute incompatibility since the extract must undergo acid digestion prior
to analysis. (See Step 8.13.2)
A trade association recommended that, although 1t 1s not necessary to
measure pH and alkalinity of the TCLP extracts, such measurements should be
taken as the Science Advisory Board recommended in 1984. These two measurements
are often useful 1n deciding whether or not measured concentrations 1n the
extract are chemically consistent with the solution characteristics. These
measurements are easy to take and can provide quality assurance checks for the
measured concentrations.
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The Agency agrees with the commenter that such data are necessary for proper
interpretation of the results and has revised the method accordingly. See Step
8.14.
One comment requested Information on the non-volatHes that should be
analyzed, on the procedures that should be followed, and on the allowable
concentration limits that apply. In addition, a trade association claimed that
Step 7.16 should specify the methods of analysis to be conducted on the
extracts.
EPA points out that the TCLP, Method 1311, is used for several regulatory
purposes. Therefore, it 1s not appropriate to Include instructions as to what
analytes should be measured in the method itself. The analytes of interest the
Toxicity Characteristic and the analytical methods required for compliance with
this regulation can be found in 40 CFR 261.24.
H. Procedure when Volatiles are Involved
The Agency received fifty-two comments which addressed Issues such as sample
size requirements and determination, particle size evaluation and reduction,
filtration in the ZHE, determination of the solid phase, the extraction fluid,
the TCLP extract preparation, and the TCLP extract analysis. These comments are
summarized and addressed below.
Sample Size Requirements and Determinations (8.1 - 8.4)
A commercial laboratory pointed out that one would need a 5 kg sample to
obtain 25 g of solid 1f the solid content is 0.5% of the total waste.
The Agency has revised the procedure to indicate that enough solids must be
generated for extraction such that the volume of extract obtained will be
sufficient to perform the required analyses. The 25 gram sample size is a
maximum, not a minimum.
A commercial laboratory also suggested that analytical laboratories
performing TCLP analyses request duplicate samples, using one to determine both
which extraction fluid to use and the percent sol Ids and using the other for the
actual extraction. The comment asserted that this would minimize the loss of
volatiles from the sample before the extraction is begun.
-------
EPA agrees with the comment and has changed the method to this effect. See
Section 7.0 - 7.5.
One manufacturer noted that, for a complex waste, it will be necessary to
use the procedures for both non-volatiles and volatiles to properly characterize
the waste. In such cases, 1t recommended that one should have to determine the
percent solids only once. (See Steps 7.0-7.6.4 )
EPA agrees and has changed the method to stipulate that percent solids is
measured using the hazardous waste filtration apparatus and the measurement
applied to both the ZHE and the conventional apparatus.
A trade association felt that the percent solid should be determined on a
"dry" basis because variation in the moisture content would also result 1n
variation in the contaminant concentration.
The Agency replies that the method is based on an extraction of a sample of
the waste that cannot be filtered under the conditions of the test. It 1s not
meant to extract "dry" solids only, because the wastes as disposed 1n a landfill
contain moisture.
Another comment stated that volatiles are always lost from samples. Thus,
the statement that reads "care must be taken to ensure these (I.e., volatiles)
are not lost," should be changed to reflect the fact that losses can only be
mi nimized.
EPA agrees and has modified the method, as suggested. Refrigeration of
samples and equipment 1s suggested in order to minimize loss of volatiles.
Particle Size Evaluation/Reduction (8.5)
In reference to particle size evaluation and reduction, some trade
associations believed sample size reduction should be performed before the
analytical sample of waste is weighed out. This same point was made in 7.11.
Loss of sample 1s unavoidable during particle size reduction. Therefore, it
should be done on the largest size sample of bulk waste. The comments suggested
that this will minimize the losses on the final analytical sample.
EPA agrees and has made this change. It is believed that this will result
in minimizing loss of sample and in maximizing sample homogeneity. (See Step
9.0.)
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Another trade association suggested that particle size reduction should be
done 1n the laboratory after the refrigerated transport and storage of the
sample to prevent loss of volatiles. This should be done since the laboratory
is usually a cooler and more controlled environment than the field. A
commercial laboratory suggested that liquid nitrogen freezing, followed by
fracturing, be considered as a size-reduction technique. It claimed that the
liquid nitrogen would minimize the loss of volatiles, make most samples brittle
and easy to fracture, and would not contaminate the sample.
The Agency notes that the method encourages cooling of the sample prior to
particle size reduction to reduce loss of volatiles. The method recommends
particle size reduction in the field, but the decision on how to handle specific
wastes 1s left to the analyst.
Another comment suggested that sieving samples to evaluate particle size
would lead to loss of volatiles since the sample would come into extensive
contact with air.
EPA agrees that particle size reduction for volatiles is a difficult issue,
and several alternative approaches are being investigated. In the meantime, EPA
is recommending that a sieve not be used to determine particle size for
volatiles. A small ruler is an acceptable alternative and its use 1s suggested
until a more adequate method is developed.
Filtration in ZHE (8.7-8.8)
One manufacturer recommended that the note associated with the correction to
the original sample weight to account for loss of sample during transfer to the
ZHE be replaced with an emphasis on the quantitative transference of the sample
to the filtration device. Such a weight correction could alter the solid to
liquid ratio of the sample and have a significant Impact on characterization of
the waste.
EPA has revised the method as suggested to emphasize quantitative transfer
of the sample. See Section 9.8.
A trade association asked whether it is necessary to use a pump to transfer
extraction fluid into the ZHE.
The Agency responds that it 1s not necessary to use a pump. One alternative
to a pump is to use another ZHE or pressure filtration device to transfer
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extraction fluid Into the extraction vessel. The procedure is outlined in
Section 9.12.
. Two comments pointed out that any fixed volume collection container used in
step 8.8 will contain headspace after the fluid is expressed from the waste. If
the volume of the container matches the volume of the expressed fluid, this
would be entirely fortuitous. Small volumes of expressed fluid can be collected
in gas-tight and PTFE syringes with fluid locks on the inlets and stored in this
manner. Tedlar bags are the only acceptable containers for large volumes, and
so the method should require them.
The EPA agrees and has changed the method to recommend the use of Tedlar
bags when the waste contains an aqueous liquid phase which subsequently must be
combined with the leachate. If the waste contains a non-aqueous liquid phase,
either a syringe or a Tedlar bag may be used. Refer to Step 4.6 for more
details.
A trade association suggested that the evacuated container which will
receive the filtrate be more fully described and the sample weighing method
which minimizes the loss of volatiles be specified.
The Agency points out that Tedlar bags or gas-tight syringes are specified
in Step 4.6 as appropriate containers to receive the filtrate from the ZHE. It
is not necessary to specify a degree of evacuation or Internal pressure for
these devices. The analyst is instructed to take the necessary precautions to
minimize the headspace in the filtrate collection containers. No single
weighing technique would be appropriate for the variety of wastes analyzed by
this method, so the selection of appropriate weighing procedures 1s left to the
analyst.
A commercial laboratory recommended that all filtration be done with the ZHE
in an upright position with the filter on the top. At the completion of the
extraction, the vessel should be placed 1n this position and the solids allowed
to settle for 5-10 minutes prior to the final filtration. This procedure will
minimize clogging of the filter during the filtration. As a quality control
step, the commenter also suggests that the Tedlar bag or gas-tight syringe be
weighed after the final filtration. This would indicate whether or not all of
the extraction fluid is recovered.
The Agency agrees. Specifying that filtration be performed with the filter
on top will ensure that results are more reproducible. Step 9.8 specifies that
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filtration 1n the ZHE must be carried out with the gas Inlet/outlet flange on
the bottom and the liquid Inlet/outlet flange (with the filter) on top.
Another comment asked why the limit of 50 pounds per square Inch gauge
applied pressure was specified for filtering samples.
EPA refers commenter to the March 10, 1986, TCLP background document for a
discussion of the rationale behind the filtration pressure of 50 ps1 (US EPA,
1986a). The pressure has been reduced from the 75 psi used 1n Method 1310 (EP)
because the glass fiber filter has a larger pore size than the membrane filter
and thus has less of a tendency to clog, allowing a reduction in the maximum
pressure.
A manufacturer recommended that the filtration step (which states pressure
is to be increased until no additional liquid has passed through the filter 1n
any 2 minute interval) be changed to a relative volume change of 1% to be
measured by weight. This suggestion was made because of the difficulty 1n
detecting flow into the Tedlar bag.
The Agency believes that 1t is easier to detect a cessation of flow than to
quantify a relative volume change. Therefore, the method has not been changed
1n this regard.
Another comment noted that Section 4.3.1 refers to the use of in-line
filters when the filter within the ZHE breaks. The comment asked for a
definition of these filters and suggests that the filter be specified as other
filters are specified and manufacturers indicated.
EPA responds that this equipment 1s commonly available from instrument
supply catalogs.
Determination of Solid Phase (8.9 - 8.10)
A trade association asserted that the note given in Step 8.9 addressing
difficult to filter wastes should be moved to Step 8.4. Another trade
t
association suggested that the term "100% solids for the procedure" as written
be defined as: that fraction of a sample from which no liquid may be forced out
by an applied pressure of 50 ps1g.
The Agency agrees with both comments. The Information in the referenced
note is specified in Steps 7.1.8, 8.8, and 9.10. The solid phase of the waste
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is defined as the material 1n the ZHE following the initial filtration, also in
the three sections referred to above.
Extraction Fluid (8.11)
One comment stated that using only extraction fluid No. 1 in the ZHE avoids
the problems of bias due to the difference in solubility of acidic and basic
compounds at different pH values. However, when extraction fluid No. 2 is used
in the extraction for metals and semi-volatile organlcs but is not used 1n the
ZHE portion of the test (for highly alkaline wastes), the volatiles analysis
will show a higher level of acids (relative to base/neutrals) than that of the
seml-volatiles. It is conceivable that a waste generator could "treat" his
waste by adjusting the pH level to the point where the concentration of
contaminants 1n the extract will be below the regulatory threshold simply by
forcing an external bias on the test instead of Improving the overall nature of
the waste.
EPA notes that the extraction of volatiles 1s not greatly affected by
changes 1n the pH of the extraction fluid. Adjusting the pH level of the waste
would be considered waste treatment and requires a permit.
A trade association noted that the TCLP procedure requires extraction fluid
number 1 be used with the ZHE. Fluid number 2, however, 1s specified for
metals in high alkaline waste. The comment asked if ZHE and metal analysis are
required on an alkaline waste, will two separate extractions be required? The
comment maintained that this would not be cost effective.
The Agency reiterates that the ZHE procedure 1s used only for determining
volatiles in the leachate. Semi-volatiles and metals analysis must be performed
on leachate obtained with the bottle extraction. EPA believes that this is cost
effective, as discussed in Section I of this document.
A manufacturer recommended clarifying Step 8.11 to Indicate that the
temperature external to the extractor is to be controlled. Another comment
asked whether the temperature of 22 +/- 3'C during agitation refers to ambient
air temperature or temperature of the contents of the ZHE.
The Agency responds that the specified temperature refers to ambient air.
The method has been clarified on this point. See Step 9.12.3.
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One trade association noted that, If the regulatory thresholds for the
Toxicity Characteristic are below the saturation concentrations for each
component, then the use of a volume of extraction fluid less than 20 times the
weight of the 100% solids sample would seem allowable. If the waste passed this
worst case condition, then the waste would pass the more dilute test.
EPA observes that, while this may be true, co-solvent effects may produce
concentrations greater than the water solubility. Standard procedures are
necessary to permit comparison of results between laboratories.
TCLP Extract Preparation (8.12 -8.14)
Several comments discussed multiphasic leachates. One trade association
noted that the method requires prior knowledge of the waste to predict if
multiphasic samples will be generated from the wastes when the initial liquid
phase is combined with the leachate. Another trade association made the same
comment and suggests that the TCLP describe a screening test to guide the
analyst in the choice of using a separate filtrate container to hold the
leachate. A manufacturer believed EPA should provide guidance for resolving
problems presented by multiphasic filtrates.
The Agency believes that generators should have sufficient knowledge of
their wastes to predict the occurrence of multiple phases 1n the filtrate and
extract. Such multiphasic samples may be analyzed separately and the results
mathematically combined to obtain the total concentration of contaminants. See
Step 9.15.
A municipal sewage authority experienced some difficulty with using Tedlar
bags for transferring sample filtrate and extract from the ZHE. The comment
noted that some amount of air invariably makes its way into the bag.
The Agency notes that any collection device will contain some air. However,
the Tedlar bags have been shown to minimize the amount of air present.
A state agency recommended modifying the description of the procedure for
checking the ZHE to be sure that pressure had been maintained during the
extraction procedure. It claimed that a liquid release would also indicate that
pressure had been maintained.
The EPA has specified that the ZHE should be checked for leaks after every
extraction by pressurizing to 50 psi and submerging it in water. See Step
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4.2.1. Step 9.13 Instructs the operator to check for release of gas from the
gas Inlet/outlet valve following the 18 hour agitation period. No release of
liquid should occur there.
TCLP Extract Analysis (8.14)
A metals processing firm recommended that other analytical procedures which
are equally valid as those included in SW-846 be approved as alternatives.
Trained analytical chemists should decide which method to use.
EPA responds that existing regulations allow companies to submit procedures
for consideration as an equivalent. Users are encouraged to submit data on
alternative procedures to the Agency for possible inclusion in future editions
of the SW-846.
I. Quality Assurance Requirements
The quality assurance requirements for the TCLP are more complex than those
for the EP and include a minimum of one blank for every ten extractions done in
the extraction vessel to check for memory effects from the extraction equipment.
Other QA requirements include the method of standard addition for each metallic
analyte if either the recovery of the compound from the TCLP extract 1s not
between 50 and 150% or if the constituent measured in the extract 1s within 20%
of the appropriate regulatory threshold. If more than one extraction is run on
samples of the same waste, the method of standard addition may be applied only
once and the percent recoveries applied to the remainder of the extractions. A
third QA requirement involves the holding times for the samples. The period
that an extract may be held before extraction and between extraction and .
analysis is 14 days for volatiles, 40 days for seml-volatiles, 28 days for
mercury, and 180 days for other metals.
Twenty-two comments expressed concern about these quality assurance
requirements. Two comments requested that EPA specify which extraction fluid
should be used as the method blank when the extractor is checked for memory
effects.
EPA replies that Extraction Fluid #1 should always be used for blank
determinations, in order to ensure consistency and comparability.
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Another comment noted that the requirement of one blank for each batch of
extraction fluid means that a blank must be run each day. This will require a
large percentage of ZHEs from most laboratories. The comment asked 1f the
extraction blank can be run directly as prepared or be analyzed only 1f the
contaminant measures above the regulatory limit. Another comment claimed that
the blanks and samples cannot be run the same day because of the eighteen hour
extraction time requirement. A major oil company questioned whether or not the
analysis of blanks on a 10% basis will be adequate 1f significant sample
carryover is observed.
The Agency responds that good laboratory procedure requires a blank for each
batch of samples. This requirement 1s a minimum. More blanks may be run, and
should be run if a problem 1s suspected. Most laboratories conducting the
analysis have multiple extraction vessels, and the vessel used for blank
analysis should rotated on a regular basis. The blank should be carried through
all steps of the procedure at the same time as the samples. The method no
longer requires that the extraction fluid be made up daily.
Several comments addressed the subject of standard additions. Two comments
concurred with EPA's approach to standard additions. Many comments requested
EPA to specify whether all possible contaminants are to be determined by Method
of Standard Additions or just the ones found above the method detection limit.
A major petrochemical company expressed several concerns with the specifications
for spiked standards. It questioned whether it is reasonable to require a 50-
i50% recovery for all spikes. Another comment stated that 1t may be difficult,
to achieve 50% recovery of phenolics spiked Into samples. Also, the MSA
4
requirement means that a minimum of two spiked samples, an unspiked sample and a
blank be run for each determination. Finally, it asked that EPA specify when the
spikes must be added (either before or after extraction).
The Agency points out that step 10.5 now states that the method of standard
additions (MSA) must be performed for each metallic analyte if recovery is not
between 80% and 120% or the measured concentration is within 20% of the
regulatory threshold. MSA is not required for organic analytes. Step 10.3
specifies that the spikes are added after filtration of the TCLP extract and
before preservation since the purpose is to evaluate the analytical method's
capacity to measure the concentration of the contaminant in the extract. Blanks
are required for each analytical batch (up to 20 samples).
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One comment noted that no definition of "spiked splits" or mathematical
analysis of "recovery" appears in Section 9.4. A laboratory suggested the use
of surrogate spikes. Another comment suggested that, for organic constituent
analysis, methods should be modified to allow isotope dilution instead of
standard addition and that a single addition technique be allowed instead of
multiple standard additions.
The Agency has deleted the reference to "spiked splits", and believes a
mathematical analysis of recovery is not necessary. Recovery should be reported
in terms of the analyte and material spiked. Surrogate spikes are not required
because the purpose of the method is not to be an efficient "extraction" but to
represent leaching potential in the field. Isotope dilution methods are
expensive and cumbersome, and have not been approved for RCRA analyses.
Two comments suggested setting a time limit for the holding time for
semi volatile samples. One also recommended holding times of 7 days for seml-
volatile samples and 14 or 21 days for metal analysis.
The Agency notes that holding times both before and after extraction are now
specified 1n step 10.6.
An industry trade association contended that the quality control
requirements of the TCLP will greatly affect the cost and productivity of the
procedure.
The Agency emphasizes that the quality control requirements are essential to
ensure the reliability and appropriate interpretation of results.
Other comments requested guidance for the time for retaining analytical and
QA data. One of these comments suggested a minimum of 3 years 1n order to be
consistent with the RCRA programs.
The Agency notes that data retention requirements are not a part of the
method, and are therefore not addressed in this background document. Such
requirements are, however, part of many regulations. The preamble to the final
rule should be consulted on this point.
a
J. Relationship of the Multiple Extraction Procedure (MEP) and 01ly Waste
Extraction Procedure (OWEP) to the TCLP (Method 1311)
The Multiple Extraction Procedure (MEP) has been used to predict the long-
term effects which acid rain may have on stabilized wastes. The Oily Waste
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Extraction Procedure (OWEP) has been used to predict the leaching of metals from
wastes which contain significant amounts of oily materials. Both methods have
been used to make waste specific determinations under the listing and de-listing
programs.
Six comments were received which addressed this topic. Two comments
supported continued use of the MEP and OWEP for the de-11sting program. One of
these comments also supported using the procedures for the listing of hazardous
wastes and recommends that EPA allow the regulated community to submit
additional alternative extraction procedures for specific wastes and disposal
practices. A major oil company recommended additional testing of the mobility
of oil in the disposal scenario. Another comment recommended testing inorganic
stabilization treatment options which may be evaluated using the MEP. A natural
gas company contended that the analytical results for metals will differ
significantly between the TCLP and OWEP.
The Agency replies that it will continue to employ the MEP and OWEP only in
the listing and de-Hsting programs where situation-specific decisions can be
made. The TCLP will be used to determine 1f a waste 1s hazardous, according to
the Toxicity Characteristic (40 CFR 261.24). Further studies are underway to
investigate whether or not changes to the TCLP can enhance the test's ability to
model the behavior of oily wastes in a land disposal environment.
K. Other Technical Comments
This section contains miscellaneous technical comments concerning the TCLP.
Some of these comments are very general while others are very specific.
The most frequent general technical comment was that the procedure is too
complicated. Several made suggestions to make the procedures easier to
understand and perform. Another comment suggested separating the procedure into
two separate documents, one for volatiles and one for non-volatiles, to make the
procedures easier to understand.
The Agency believes that the changes in the procedure resulting from EPA's
reevaluation and the comments received have made the procedure easier to
understand and perform. Changes are documented in a subsequent section of this
report.
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Sampling guidance was another topic that elicited multiple comments. Three
comments requested guidance 1n obtaining representative samples. One comment
requested that the procedures provide methods for determining sampling frequency
and replication, as well as an indication of the appropriate measure for
comparing with the regulatory level.
EPA replies that additional sampling guidance is provided in Chapter 9 of
the third edition of SW-846. The Agency 1s currently developing a more detailed
guidance on appropriate sampling measures.
A trade association recommended a three year sunset provision to enable EPA
periodically to update the protocol as new analytical tools are developed.
The Agency disagrees. Monitoring and updating of the procedures are
constantly being performed by the Agency.
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VI. Comments on May 24, 1988, Proposed Modifications
In response to comments on the particle size reduction requirement, the EPA
reviewed the use of the Structural Integrity Procedure, which employs a drop
hammer to test the integrity of solidified and monolithic wastes. The Agency
found that certain materials maintained their integrity in the SIP, but when
they subsequently were placed into the glass extractor bottles and rotated the
bottles would break. The Agency developed a cage insert for the bottles in
order to prevent breakage when solidified or monolithic materials were
extracted. While evaluating the utility of the cage to prevent breakage of the
bottles, the Agency noticed that wastes that were believed to be wel1-solidified
retained their monolithic nature in the cage during extraction, whereas wastes
that were believed to be less well-stabilized broke into small pieces.
The Agency conducted further evaluations, as discussed 1n the May 24, 1988,
Federal Register notice, 53 FR 18792 - 18797, and preliminary results suggested
that the cage tumbling procedure may correlate better with the environmental
stability of the waste than the SIP. Based on these results, the Agency
proposed that most waste materials need not be milled to pass the 9.5 mm sieve
before testing if (1) the bottle extractor equipped with the cage is employed
and (2) an appropriate size representative sample can be taken and analyzed.
The exception would be wastes that are rendered monolithic by being encapsulated
and wastes that are tested for volatlles.
Eight commenters indicated that although the proposed cage modification is a.
move in the appropriate direction toward a realistic assessment of the
environmental leaching potential of a solid waste, the modification was
prematurely proposed. Several commenters declared that the cage modification
should not have been proposed before the EPA and ASTM round robin testing has
been completed. Other commenters noted that available data are insufficient to
determine the impact the proposed change will have on method performance and
compliance determinations.
One commenter requested that EPA "hold the proposal in abeyance" for one
year for additional testing and evaluation of the proposed change. They
suggested that EPA publish a supplemental notice in one year, making additional
data available for public review and comment. Along the same lines, another
commenter requested that EPA accept additional comments once testing of the cage
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is completed. The commenter 1s currently performing tests using the cage; once
these are complete they will analyze the resulting data and develop comments and
suggestions to be submitted to EPA.
One commenter questioned the validity and reproducibility of the TCLP, as
well as specific test requirements such as that for milling or grinding
solidified wastes. They claimed that current data are insufficient to evaluate
whether the cage tumbling technique would adversely affect the determination of
compliance with regulations and treatment standards developed based on TCLP
tests using the milling/grinding technique.
The Agency agrees that additional data on performance of the stainless steel
cage are needed, and has decided not to go forward with the cage modification at
this time.
One commenter, a participant in the joint EPA and ASTM round robin testing
of the proposed modification, reported problems with nickel leaching from the
stainless steel cage and equipment Incompatibility with wastes that evolve gases
when in contact with water.
The Agency feels that leaching from the cage may not be a major problem.
However, until additional information is available from studies currently under
way, the Agency has decided to postpone a final decision on the use of the
stainless steel cage.
Several commenters suggested that the new test method may not be truly
representative of actual conditions existing in various landfills and waste
disposal sites. They were concerned about the unnatural abrasive action of the.
cage on the wastes. One commenter believed that the tumbling action of the
solid sample in the cage could cause particles to be sloughed off by abrasive
action and that leaching from these particles would be greater than that of the
solid mass of the waste itself. They recommended securing the solid sample
within the cage or casting the wastes in the exact shape and size of the cage.
Another commenter recommended performing comparative testing for metals on
wastes extracted with and without the cage.
The Agency notes that use of the stainless steel cage 1s not an attempt to
replicate any specific landfill conditions. Rather, it is an attempt to give
credit to solidification processes and to wastes that are relatively impermeatfe
and structurally stable and are likely to remain so after disposal. The Age"c>
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has generally found that wastes that are well solidified maintain their
integrity after tumbling in the cage whereas wastes that are poorly solidified
break up 1n the cage. However, the Agency has determined that additional
studies on the effect of the stainless steel cage and operational aspects of the
procedure are necessary before this proposed modification can be finalized.
Three commenters believed that because the cage's construction provides
numerous crevices and a significant amount of surface area for waste residue to
collect, an effective cage cleaning method must be developed and specified in
the text of the TCLP method.
The Agency agrees that an effective cage cleaning method should be
developed. However, since the Agency has decided to postpone a final decision
on the cage, a cleaning procedure 1s moot at this point.
One commenter claimed that the specified cage for the TCLP method 1s not
compatible with most of the commercial rotary agitators currently 1n service.
They stated that 1t would be "an unnecessary financial hardship to the hundreds
of commercial and government labs ... to purchase redesigned agitators to suit
the cage modifications as proposed." They also suggested that the free-fall
length of the cage be specified as a proportion of sample height, thereby
allowing the use of different sized bottles.
The Agency agrees and has changed the free-fall length specification to 9.0
+/- 0.1 inches and the diameter to 3.0 +/- 0.1 Inches in order to accommodate a
greater variety of bottle sizes. Additional Investigations are needed to
determine whether this modification will impact the results of the test.
Four commenters were concerned that the shock absorbing springs on the
stainless steel cage of the modified TCLP apparatus exert too much force,
thereby creating a safety hazard. One commenter recommended that the spring
force be reduced by at least 50 percent. On the same note, another commenter
reported numerous broken leaching bottles in their studies, which they attribute
to the coupling of stresses from the cage springs and the rotary extractor
clamp.
The Agency agrees that the force of the springs 1s excessive and has asked
the manufacturers to redesign the cages to exert less force.
Six commenters suggested that freeze/thaw and wet/dry studies do not
accurately simulate actual landfill conditions. One commenter contended that
wastes may be subjected to colder temperatures in Subtitle C landfills only once
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when they are first placed 1n the landfill 1n freezing temperatures. They also
felt wastes will not be subject to 28 wet/dry cycles in a landfill environment.
Five other commenters agreed that most hazardous waste is disposed of below the
regional and/or average U.S. annual frost penetration; therefore, the test
should not be based on freezing and thawing but rather on unconflned compressive
strength.
One commenter additionally claimed the waste 1n the landfill may become
wetted with leachate which passes through the disposal unit, but the material
will attain an equilibrium level of moisture and will not 'dry out' as assumed
in the wet/dry tests.
Another commenter declared that although a monolithic block may form after
stabilization, it will eventually disassociate. This commenter stated that "all
stabilized wastes will, at one time or another, break-up and disassociate to one
degree or another." The waste at this point would come Into contact with ground
water and a leachate would be formed. Therefore, they believed that Method 1311
should not be changed as proposed.
The Agency responds that 1t 1s not known whether or not stabilized wastes
will inevitably break up in the landfill environment. Wet/dry and freeze/thaw
tests are commonly used to test the long-term integrity of structural materials
and it is assumed that the wastes passing these tests will usually remain in a
monolithic form under landfill conditions. Additional information on the long
term integrity of stabilized wastes 1s needed.
Five commenters stated that grinding penalizes the solidification industry,
and they also believed that monolithic samples that are to be tested for
*
volatile organic constituents (VOCs) should not be milled as part of the
procedure. It is generally believed that grinding these wastes results in
substantial loss of organic constituents due to volatilization. Thus, accurate
analytical determination of these constituents would be impossible. One
commenter noted that grinding wastes also penalizes those facilities where
wastes are solidified or whose wastes are already 1n monolithic form.
Two commenters addressed the concern that milling solidified waste does not
represent actual conditions that exist in a landfill. These companies urged the
Agency to develop testing procedures that would test a waste in the same
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physical form In which It will be exposed to landfill leaching conditions. The
milling procedure would produce material that is no longer representative of the
waste that 1s actually being disposed.
One commenter recommended that alternative designs of the ZHE be accepted,
so that the cage approach can be applied to wastes with volatile constituents.
They believe that grinding a waste prior to testing in the ZHE will restrict
acceptable disposal techniques and penalize confinement techniques of
stabilization and encapsulation.
The Agency is not aware of any alternate ZHE design that will accomplish the
goals of Method 1311 with minimum volatile loss. If such a design 1s developed,
the Agency will consider it for adoption. Currently, samples to be analyzed for
volatile constituents will still have to be ground. When and if the Agency
develops or becomes aware of validated procedures for overcoming this problem,
changes will be considered for Method 1311.
One commenter recommended that cryogenic crushing of solids be employed.
They reported success using a process that coates samples and grinding/milling
equipment with liquid nitrogen before processing.
The Agency notes that this is a good technique for particle size reduction
and Method 1311 allows Its use. However, the high cost Involved prevents EPA
from requiring its use in all cases.
Another commenter suggested that the Agency use a procedure similar to a
method currently being developed by the ASTM D.34 committee for determination of
the absorption coefficient of soils. This procedure Involves tumbling soils in
water containing dissolved volatile organics. The tumbling 1s performed in
bottles with septum caps, and thus no headspace. This allows samples to be
withdrawn directly from the bottle using a syringe. An analogous procedure*
could be used to determine the volatiles leached from solidified wastes. A
multi-laboratory validation study has demonstrated that loss due to
volatilization 1s minimized during this procedure.
The Agency considered the use of 40 ml VOA vials with septum caps for the
extraction of volatiles from solidified wastes, but decided that 1t would be
very difficult to obtain representative waste samples of the small size that
would be required. The Agency also considered the use of the bottle extractor
and cage with a septum cap, but determined that it would not be possible to
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design a bottle that could hold exactly 100 grams of waste and 2 liters of
extraction fluid with no headspace for all types of monolithic wastes. Thus,
the Agency will continue to require use of the ZHE and grinding of wastes to be
analyzed for volatile constituents.
Three commenters indicated that wastes less than 9.5 mm in diameter should
not be milled. One commenter urged the Agency to reconsider the requirement to
use the cage in the extraction bottles for samples already finely divided (i.e.,
samples less than 9.5 mm). They noted that for samples already "pulverized" a
test of their structural integrity is useless. They also pointed out that this
further complicates the procedure and presents an equipment cleaning problem.
Another commenter suggested that a requirement to use the cage with wastes
that are already smaller than 9.5 mm is inconsistent with the intent of the cage
modification. The cage modification tests the resistance of such wastes to
environmental stresses. However, wastes passing through a 9.5 mm sieve without
processing are not subjected to such stresses. In addition, 1t 1s noted that
there is no explanation why wastes undergoing size reduction are extracted
without the cage and wastes not requiring size reduction (because they pass a
9.5 mm sieve) should be extracted with the cage in place.
The Agency generally agrees and will address these comments when and if it
proceeds with the cage modification.
Seven commenters declared that the requirement that encapsulated wastes be
ground or milled is inappropriate. Specifically, one commenter recommended that
encapsulated wastes be pre-formed into cylinders or blocks to fit the extraction
cage as 1s proposed for fixed or stabilized wastes. Other commenters indicated
that EPA has not adequately evaluated all encapsulation techniques prior to the
proposed modification.
The Agency feels that until sample integrity and leaching prediction
improve, modifications to Method 1311 must be conservative. The Agency welcomes
additional information regarding encapsulation techniques. Modifications will
be made to the procedure as additional data become available and justify the
change.
One commenter suggested that encapsulation techniques vary greatly in the
degree of confinement. Radioactive waste, for example, is encased in a binder
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such as cement as opposed to a thin protective coating. They noted that, 1n
instances such as this, the waste is similar to a stabilized monolith and should
be treated as such. Another commenter suggested that the Agency should allow
materials that 1t considers "stable, non-corrodible, encapsulated wastes" to be
extracted without size reduction. They Indicate that these wastes could be
visually distinguished from those 1n corrodible shells. A third commenter
declared that the requirement to reduce the size of encapsulated waste negates
the purpose of encapsulation (I.e., to prevent the waste from coming into
contact with landfill leachate). They agreed that milling products having the
potential for internal corrosion (e.g., batteries) is reasonable, but
recommended that vitrified or polymer encapsulated wastes be exempted from the
size reduction protocol.
The Agency agrees that encapsulation techniques vary greatly in their degree
of confinement. EPA is currently working with the Department of Energy (DOE) in
developing a definition for encapsulation that will distinguish between those
wastes that are non-corrodible and stable from those that are corrodible.
In response to EPA's Invitation for comment on how to define "stable, non-
corrodible, and encapsulated" wastes, one commenter suggested that the Agency
follow the precedent that has been established by the Nuclear Regulatory
Commission (NRC). This commenter indicated that existing NRC criteria for
radioactive wastes appear to be applicable for other wastes that will be land
disposed. They noted that EPA's use of current definitions would eliminate the
need for duplicate efforts and improve regulatory consistency among Federal
agencies.
The Agency agrees with this commenter that defining "stable" in the manner
found in 10 CFR Part 61 (Stable: Maintaining gross physical properties and
identity) may be a reasonable approach, however 1t lacks any time component.
The remaining two definitions, "non-corrod1ble" and "encapsulated," were not
found to be referenced 1n 10 CFR Part 61. The following are some preliminary
draft concept definitions under consideration.
Non-corrodible: Able to survive in the environment over an
extended period of time without chemical change in exposed
surfaces.
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Encapsulation: Application of a surface coating through
coating/sealing, or placement in specially designed/sealed
containers, which provides a surface barrier that prevents contact
between the waste and leaching fluids that may be present 1n the
environment and that exhibits long-terra stability.
One commenter indicated there 1s a discrepancy 1n distinguishing between
stabilized monoliths and various types of encapsulated wastes. They noted that
High Integrity Containers, designed to survive in the environment for a minimum
of 300 years, provide containment similar in concept to the liners required for
hazardous waste disposal facilities. Encapsulation techniques vary greatly in
the degree of confinement provided and, therefore, should be evaluated on an
individual basis and differently from stabilized wastes.
The Agency agrees that encapsulated and stabilized wastes are very different
and EPA is investigating different approaches to regulating these types of
wastes. However, sufficient information on the behavior of these materials 1n
landfills is not yet available.
One commenter claimed that the term "equivalent material," with regard to
the construction material for the cage, should be better defined. They believed
that criteria used in judging equipment equivalence (e.g., structural strength,
chemical inertness) should be specified. This would allow the users of the test
to rationally judge the acceptability of cage designs other than those
constructed of 100 percent stainless steel.
The Agency feels the term "equivalent material" 1s satisfactory and needs no
«
further explanation. Equivalency 1s further defined in the Agency's hazardous
waste methods Equivalency Guidance Manual. ("Test Method Equivalency Petitions:
A Guidance Manual"; EPA/530-SW-87-008; OSWER Policy Directive Number 9433.00-2,
February 1987.)
One commenter suggested that EPA should not modify the TCLP as proposed by
eliminating the requirement for particle size reduction. The commenter declared
that the proposed modification to the TCLP would increase the threat of
pollution from landfill leachate and would encourage accelerated landfill
utilization and expansion with no environmental gain.
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The Agency responds that there 1s not enough information to determine the
extent to which the proposed modification would effect waste characterization
results. For example, work reported at the 1988 Symposium on Waste Testing and
Quality Assurance (Prange and Garvey, 1988) shows that larger particles may
actually leach more readily than smaller particles. Experiments with two
specific cement-solIdified wastes demonstrated that arsenic and chromium were
leached more effectively from large rather than small waste particles by the
TCLP extraction. As previously stated, the Agency has decided not to go forward
with the proposed cage modification at this time due to insufficient evaluation
and the potential problems experienced with leaching of nickel and chromium,
cleaning the cage, and some other operational difficulties.
One commenter referred to comments submitted on the previous proposals
regarding the TCLP, and repeated their opposition to the proposed rulemaking and
the "TCLP method per se."
The Agency addressed comments of this nature 1n other sections of this
background document.
One commenter suggested changes 1n two sections of the flowchart addressing
particle size reduction.
The Agency disagrees with the suggested changes because they deviate from
standard flowchart format found 1n the guidance manual "Test Methods for
Evaluating Solid Waste, Physical/Chemical Methods," SW-846, and provide no
additional technical guidance.
One commenter agreed that EPA 1s correct 1n Its conclusion that the cage
modification would not have an economic Impact resulting 1n annual expenses
exceeding $100 million.
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VII. Analytical Constraints
The regulatory levels for the compounds proposed for inclusion in the
expanded Toxicity Characteristic span about 5 orders of magnitude (I.e., from
the low parts per billion to 100 parts per million). This is not so much a
function of the Individual dilution/attenuation factors but 1s due instead to
the great range in toxicity levels of the individual toxicants. Since many of
the toxicity levels for the carcinogens (and some of the non-cardnogens) are
very low, the calculated regulatory threshold will also be very low (depending
on the magnitude of the dilution/attenuation factor). The proposed regulatory
thresholds were below the practical quantitation limits (PQL) which can be
measured with current methodology for seven compounds. Due to changes in the
chronic toxicity reference levels and the dilution/attenuation factors, the
final regulatory levels are below the PQL's for three compounds (2,4-
dinitrotoluene, hexachlorobenzene, pyridine).
The Agency received eighty-two comments which address the topic of
analytical constraints on the use of the TCLP in the Toxicity Characteristic.
These comments came from consultants, research laboratories, petroleum/chemical
companies, trade associations, state and federal agencies, municipal sewer
authorities, waste management companies, electric utilities, and other
industries. The comments were grouped into three areas: use of quantitation
limits as the regulatory level for some compounds; analytical methods in
general; and SW-846 Method 8270.
A. Use of Quantitation Limits
EPA proposed to deal with calculated regulatory thresholds which fall below
the analytical detection limit by establishing technology-based regulatory
levels. The lowest contaminant concentration that can be reliably measured
within specified limits of precision and accuracy during routine laboratory
operating conditions 1s the quantitation limit. The quantitation limit
represents the lowest level of measurement which can be achieved by good
laboratories within specified limits during routine laboratory operating
conditions. The quantitation limit 1s determined through Inter-laboratory
studies (I.e. performance evaluation studies).
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If data are not available from Inter-laboratory studies, quantitation limits
are based upon the method detection limits and an estimate of a higher level
which would represent a practical and routinely attainable level with relatively
high certainty that the reported value is reliable. EPA proposed using a value
of five times the analytical detection limit as the quantitation limit and
proposed setting the regulatory level at the quantitation limit for those
compounds for which the calculated health-based threshold falls below the
quantitation limit.
Some comments supported EPA1s proposal. Two stated that, when detection
limits are a problem, the samples could be concentrated to as low as 100
microliters from the EPA-spec1fied 1-mL samples (to increase sensitivity by a
factor of 10). Gas chromatography program rates can also be changed, in some
cases, to optimize the sensitivity for a particular compound.
The Agency responds that, when semi-volatile compounds are the analytes of
interest, concentration of the sample to a 100 microliter volume may result 1n
the loss of significant amounts of the analytes. GC program rates are optimized
to produce certain results, and changes to the program may Involve a trade-off
in that sensitivity to other analytes may be compromised. The reproducibility
of the analysis may also be affected. Therefore, the Agency does not recommend
changing the GC program rates.
Several comments gave qualified support for the use of quantitation limits
defined as five times the detection limit for the compounds with health-based
thresholds below this level. One asserted that the detection limits listed in .
the proposed rule apply to water samples only and may not be applicable to more
complex matrices. Other comments also expressed concern about whether or not
these detection limits apply to waste samples encountered in the RCRA program.
One stated that the use of five times the detection limit observed in water is
not appropriate for samples containing filterable oil, since the liquid oil
phase must be analyzed for the contaminants. Analyzing non-aqueous phases
*
usually results in increased detection limits relative to water because of the
severe dilutions that are associated with the digestion procedures used on oil
samples.
All of these comments urged EPA to determine actual quantitation limits of
the regulated compounds in real wastes and establish a procedure to handle
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situations where quantitation at the regulatory level 1s not possible. One
comment stated that, if an analytical level of five times the detection limit is
not achievable 1n real waste extracts, the analytical level should be determined
by extracting the waste after the waste has been spiked with substances of
interest. The analytical level could then be established on a case by case
basis. The method of standard addition could also be used 1n such cases. Also,
one comment recommended that EPA should state the calculated health-based
threshold levels for compounds with higher detection or quantitation levels.
This would eliminate the need for amending the regulatory level for a compound
if the analytical methodology improves. Another comment stated that compound-
specific evaluation is necessary to Insure that regulatory levels are not
unreasonably high for extremely toxic constituents.
Many comments criticize the proposed quantitation limits. Several comments
indicated that the proposed limits may not be technically and/or economically
achievable for specific wastes. One comment stated that it is inappropriate to
use the quantitation limit observed in water for waste extracts and filtrates,
and noted that experience with actual waste leachates has shown that these are
complex matrices in comparison with water. This comment recommended that
quantitation limits be determined on a case-by-case basis to account for the
varied matrices, and that EPA specify definitions and calculation methods for
method detection limits and quantitation limits.
Other comments also stated that 1t is inappropriate to equate the
quantitation limits observed 1n water with that of the TCLP extract. The TCLP
extract will contain many contaminants derived from real wastes that cause
analytical interferences and the TCLP leaching fluid itself contains a
significant concentration of acetic acid. This comment recommends utilizing" the
existing contract required detection limits (CRDLs) for medium soil/sediment
available from the EPA Contract Laboratory Program (CLP) for estimating the
quantitation limits for real wastes.
Two comments stated that EPA's selection of regulatory limits is premature
and arbitrary. These commenters stated that the MDL is only an estimate and
that the values listed in the Federal Register may be found to be inappropriate
when the actual waste extracts are analyzed. One suggested that the table
showing detection and quantitation limits should be altered to show either the
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detection and quantitation limit for each mode of detection or for the least
sensitive form of measurement. This comment stated that whatever modification
is made, the detection and quantitation limits should be consistent and
scientifically correct.
Twenty-four comments supported alternatives to the proposed quantitation
levels. Some supported higher quantitation limits, while others supported the
use of detection limits or other alternatives.
Nineteen comments supported higher quantitation limits than those proposed
by EPA. Some of these suggested a factor of 10 times the analytical detection
limit as the defined quantitation limit, while a factor of 25 was recommended by
others. Still other comments suggested that a factor of 10 be used for
relatively clean sample matrices, but for more complex matrices (especially
nonhomogenous, viscous, oily, or otherwise more analytically intransigent
solids) a factor of 25 times the detection limit should be used. One suggests
adopting the approach described by the American Chemical Society's "Principles
of Environmental Analyses" Anal. Chem. 1983, pp. 2210-2218. All of these
comments indicated that such changes are necessary because of problems Inherent
in the analyses and because of the variability of accuracy and precision even
under ideal laboratory conditions found in inter-laboratory studies.
The Agency agrees that the ability to achieve the quantitation levels listed
in the proposed rule depends strongly on the type of waste which is being
analyzed. It is recognized, however, that determination of a matrix dependent
quantitation limit would require analysis of a variety of wastes. EPA feels
that it is impractical to perform waste-specific analyses to Investigate the
effect on quantitation limits at this time. Therefore, EPA has chosen to use
five times the method detection limit as the quantitation limit.
Another comment stated that setting the quantitation limit at 5 times the
detection limit 1s unreasonable for detection limits of less than 10 ppb, since
analytical variability 1n this concentration range 1s greater than at higher
levels. This comment suggested that a sliding scale tailored to the detection
limit would be more appropriate. Such a scale should use a factor of 10 for
materials with a detection limit of 1 ppb or less and a variable factor starting
at 10 and ranging down to a factor of 5 at 10 ppb or above. This would allow
for the greater variability inherent in measurements of very low concentrations.
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The Agency notes that the compounds for which the health-based threshold is
less than five times the detection limit have detection limits of 10 ppb or
greater.
Three comments supported the use of the analytical detection limits as the
regulatory threshold. These comments stated that, for carcinogens, the use of a
quantitation limit 1s Inappropriate. The goal is to achieve the safest
environmental conditions, and the detection limit represents the lowest
achievable measurement (even 1f not consistently achieved). Therefore, using
the analytical detection limit would be more protective of human health and the
environment, and will have the dual effect of somewhat lowering the cancer risk
posed by these carcinogens and encouraging laboratories to develop better
analytical capabilities. One comment recommended that EPA pursue the
development of more sensitive analytical methods that would allow the
quantitation of these carcinogens at the 10"^ risk level.
The Agency responds that it is constantly striving to improve the
sensitivity of analytical methods 1n order to provide Increased protection for
human health and the environment. Analytical detection limits are, by
definition, not routinely achievable under average laboratory conditions. Thus,
a regulatory level set at the detection limit would be difficult to enforce and
difficult for the regulated community to demonstrate compliance. In order to
provide a consistently enforceable regulatory limit, the Agency has decided to
define the quantitation limit as five times the detection limit and to set the
regulatory level for the five compounds at the quantitation limit.
Another comment favored establishing regulatory levels which are based on
treatment technology rather than measurement technology. This comment also
noted that any change 1n the regulatory level established in the regulation must
be subjected to the rule-making process and not automatically based on improved
detection limits or treatment technology.
The Agency responds that the Toxicity Characteristic 1s a health-based
regulation, not a technology-based regulation. The Agency agrees that changes
in levels are subject to the federal rule-making process.
One commenter expressed concern that the action levels proposed by EPA are
below the ability of existing analytical procedures to detect, and therefore the
commenter would be unable to demonstrate that Its waste (specifically, landfill
gas condensate) is non-hazardous.
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The Agency points out that this comment demonstrates a misunderstanding of
the proposed rule. In both the proposed and final versions of the Toxicity
Characteristic, when the calculated regulatory threshold for a pollutant close
to the analytical detection limit, the threshold is set at 5 times the detection
limit, defined as the quantitation limit. Therefore, if a generator can
demonstrate that the concentration of regulated substances in the TCLP extract
is below the quantitation limit, the waste is non-hazardous according to the
Toxicity Characteristic.
B. Analytical Methods - General
The test methods proposed for analysis of TCLP extracts for compliance with
the Toxicity Characteristic were listed in the Federal Register (Friday, June
13, 1986, pp. 21672-21673, Table C-2). These methods are contained in EPA
publication SW-846, "Test Methods for Evaluating Solid Wastes".
One comment supported EPA's proposed analytical methods, stating
specifically that GC/MS should be used for identification and quantitation of
organic compounds since GC/MS is a definitive method which will facilitate the
enforcement of the proposed rule.
Nineteen comments gave qualified support for the proposed analytical
methods. Many expressed concern over the relatively small number of
laboratories which can perform the TCLP and associated analyses. The consensus
was that the high cost and specialized nature of these tests would force most
customers to use commercial laboratories that are participating in EPA's
contract laboratory program under Superfund. These laboratories already have
high sample loads, and additional work will result in substantial delays, high
prices, or both.
The Agency replies that independent laboratories and the regulated community
have had sufficient time to prepare to perform the TCLP since Its proposal on
June 13, 1986. The method is already required for demonstrating compliance with
the Land Disposal Restrictions Rule promulgated on November 7, 1986 (51 FR
40643-40652). In addition, the modifications to the Toxicity Characteristic
will not take effect until six months after publication of the final rule in the
Federal Register.
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One comment stated no specific objections to the analytical methodology in
the proposed rule. However, the revised SW-846 method manual should be made
available before the rule is finalized.
The Agency notes that the Third Edition of SW-846, "Test Methods for
Evaluating Solid Waste-Physical/Chemical Methods", was announced in the Federal
Register on March 16, 1987 (52 FR 8072). It is now available through the U.S.
Government Printing Office, Washington DC, 20402, Publication Number 955-001-
00000-1, at a cost of $110, which includes future updates.
Three comments stated that equivalent EPA approved methods (which may be
more cost effective and provide the same accuracy) should be allowed. For
example, an alternative to GC/MS for volatlles is purge and trap gas
chromatography with tandem detectors (such as the Hall detector for chlorinated
volatiles and the photoionization detector for volatile aromatics). This
essentially combines methods 8010 and 8020. A separate portion of the extract
could be purged and trapped on a gas chromatograph using a flame Ionization
detector for those compounds for which neither the hal1de specific detector nor
the photoionization detector is applicable. Similarly, sem1-volat1le
chlorinates can be analyzed with Method 8120.
The Agency agrees that several methods are available to conduct the required
analyses. Methods approved for demonstrating compliance with the Toxicity
Characteristic appear in SW-846, and the analyst may choose from among these
methods when performing the analysis. Additional methods may be submitted to
the Agency for review and evaluation, and may be Included in future editions of
SW-846.
Two comments made suggestions for dealing with potential analytical
problems. Since interferences with halogenated compounds or background problems
are a problem on an ECD, capillary columns, rather than packed columns (Method
8080), should be used for the pesticides. Also, Identification should be used
for the pesticides. The Identification should be verified by GC/MS where the
concentration permits.
The Agency notes that, 1n the revised SW-846 manual, alternative gas
chromatography columns are allowed If appropriate quality control procedures are
followed. Method 8000 (Gas Chromatography) discusses equipment, procedures, and
quality control for all GC analyses.
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Six comments criticized the proposed analytical methods. Some concern was
expressed over the high variability of the SW-846 methods. One comment stated
that either the analytical methods are being pushed to their limits of being
able to accurately quantitate the components 1n the extract or there is a
persistent problem with matrix Interference. Two comments supported and
encouraged EPA to revise the analytical methods based on rigorous inter-
laboratory testing and validation.
The Agency states that the Third Edition of SW-846 contains additional
method performance data. SW-846 methods are comparable in performance with
analytical methods used in the water and wastewater program and the Superfund
program.
The fact that atomic absorption methods are unable to distinguish among the
various forms of chromium and therefore only measure total chromium was a
concern of one comment.
The Agency is aware of the analytical problems associated with chromium. For
this reason it regulates total chromium, and 1s continuing to investigate
alternative analytical procedures to distinguish between the various forms of
the element.
Finally, one comment stated that, since 1t seems apparent that the Toxicity
Characteristic list will be expanded to include a broadened spectrum of organic
compounds, EPA should actively seek to establish reliable and cost effective
indicator analyses that can be used to screen for classes of compounds that are
of concern. GC/MS analyses may not be appropriate 1n all cases when the true
concern should be a less rigorous and more cost effective measure of the degree
of hazard posed by a waste.
The Agency agrees that reliable and cost effective indicator analyses are
desirable. Research 1s currently being conducted in this area. New methods
will be announced for public comment when available, and Included in SW-846 when
validated.
C. SW-846 Method 8270
As discussed in the preamble to the proposed rule, analyzing the TCLP
extract for phenolic compounds and phenoxy acid herbicides poses a potential
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analytical problem. The leaching fluid used in the new leaching procedure is
0.1 M with respect to acetate. Because of interference from the acetate ion,
the analytical method most frequently used for these compounds (i.e., GC/MS SW-
846 Method 8270) may not suffice. EPA is currently investigating these methods
to ascertain whether they are sufficient or whether it may be necessary to
modify these methods. One modification being investigated is whether 1t may be
possible to remove the acetate ion from the extract before determination of the
phenol1cs and herbicides.
EPA 1s also investigating the use of high pressure liquid chromatography
(HPLC) using electrochemical and fluorescence detection. HPLC with fluorescence
detection was used in developing the improved leaching procedure and has been
shown to produce acceptable results. A GC/MS method would be preferable since
using the HPLC method could add significantly to analytical costs. Should the
presence of the acetate 1on present substantial problems to GC/MS, HPLC may be
specified.
Five comments presented evidence supporting removal of the acetate 1on from
the extract before determination of the phenolics and herbicides using GC/MS.
Two comments address the complications caused by the use of acetic acid in the
leaching procedure. Whereas the problem is greatest with the phenols and
cresols, another step 1s needed even for the nonionizable species to eliminate
the acetate from the methylene chloride extract. Analysis by EPA Method 8270
may lead to the destruction of the GC column. Without the ability to analyze
the acid fraction, a number of environmentally significant (and water soluble)
compound classes (I.e., phenols) will be overlooked. Development of a method
such as reverse phase open column cleanup was recommended 1n one comment as a
means for dealing with the acetate ion. Another comment asserted that the
analysis of the extract for acid compounds by GC methods will be impossible
because of the acetic acid matrix interference.
The Agency agrees that analysis for acidic compounds by GC methods may be
difficult. The use of a bonded-phase capillary column can reduce the
interference from acetate. Methods for acetate removal are still under
investigation. The Agency welcomes alternative suggestions, especially when
accompanied by supporting data.
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Ten comments addressed alternatives to GC/MS. Three of these believe that
HPLC should riot be recommended because of its higher cost and lack of
availability. Three others indicated that GC/MS was a better method than HPLC.
One stated that there is no description of how the HPLC method would be
implemented. At the very least, a lengthy verification process would be
required. Even if a good HPLC cleanup is approved, use of the method is bound
to increase the analytical costs and slow down the analytical throughput.
The Agency agrees that the specificity of GC/MS analysis is more
advantageous than the HPLC, in despite of the associated difficulties. HPLC
methods for phenols are not included in the Third Edition of SW-846 due to the
lack of validation data.
Four other comments stated that such a major rule should not be proposed
while EPA is uncertain about how the analysis should be performed. It was
recommended that EPA investigate the need to monitor phenols and cresols and
determine if such monitoring is premature, considering the associated analytical
problems. One commenter opposes establishing a regulatory level for cresols
until the analytical problems are resolved.
The Agency replies that it is possible to analyze for total cresols, while
it is not possible to separate the "m" and "p" isomers. For this reason, the
regulatory level has been established for total cresols ("o", "m", and "p"
isomers).
One final comment stated that, due to the limited ability of GC/MS to handle
polar compounds, the Agency is considering using a less specific nondeflnitlve
method (i.e. HPLC with either electrochemical or fluorescence detection). This
mode of detection is not specific enough for analysis 1n enforcement situations.
A better approach would be thermospray/HPLC/MS (TSP-LC/MS) for the following*
reasons:
• Provides definitive and specific results for polar compounds;
• Consistent with previous Agency choice of definitive analytical
methods;
• No significant added expense for implementing the HPLC;
• Eliminates costly false positive values;
• TSP-LC/MS are commercially available and can be easily retrofitted to
most instruments; and
• Electrochemical and fluorescence detectors have little specificity and
are subject to interferences from other chemical species.
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The Agency notes that thermospray is very expensive and that such a method
has not yet been standardized. The EPA welcomes the submission of performance
data for alternative methods.
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VIII. Changes to the TCLP
A. EPA Changes Made Prior to Review of Public Comments
EPA has identified a number of technical and procedural changes to the TCLP
based on Its own further evaluation of the method. Specific changes are noted
below. Section numbers refer to the proposed method (51 FR 21685-21691).
Section numbers in the final version of the method appear in parentheses.
2.3 This step is changed to say "If compatible (i.e., multiple phases will not
form on combination)..." The change reflects the deletion of the formation of a
precipitate as condition of incompatibility.
4.2.1 Add: For the ZHE to be acceptable for use, the piston within the ZHE
should be able to be moved with approximately 15 ps1 or less. If 1t takes more
pressure to move the piston, the 0-r1ngs 1n the device should be replaced. If
this does not solve the problem, the ZHE is unacceptable for TCLP analyses and
the manufacturer should be contacted.
4.2.1 Add: The ZHE should be checked after every extraction. If the device
contains a built-in pressure gauge, pressurize the device to 50 psi, allow it to
stand unattended for 1 hour, and recheck the pressure. If the device does not
have a built-in pressure gauge, pressurize the device to 50 psi, submerge it in
water and check for the presence of air bubbles escaping from any of the
fittings. If pressure is lost, check all fittings and inspect and replace 0-
rings, if necessary. Retest the device. If leakage problems cannot be solved,
the manufacturer should be contacted.
4.2.2 Add: It 1s recommended that borosilicate glass bottles be used over other
types of glass, especially when inorganics are of concern. Plastic bottles may
be used only if inorganics are to be investigated.
4.6 Add instructions on choosing a collection device to be used with the ZHE as
follows:
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4.6.1 If a waste contains an aqueous liquid phase or if a waste does not
contain a significant amount of non-aqueous liquid (I.e., <1% of total waste),
the TEDLAR bag should be used to collect and combine the Initial liquid and
solid extract. The syringe is not recommended 1n these cases.
4.6.2 If a waste contains a significant amount of non-aqueous initial liquid
phase (i.e., >1% of total waste), the syringe or the TEDLAR bag may be used for
both the initial so-lid/liquid separation and the final extract filtration.
However, analysts should use one or the other, not both.
4.6.3 If the waste contains no initial liquid phase (1s 100% solid) or has no
significant solid phase (is 100% liquid), either the TEDLAR bag or the syringe
may be used. If the syringe 1s used, discard the first 5 mL of liquid expressed
from the device. The remaining aliquots are used for analysis.
7.0 - 7.5 (New Section on Preliminary TCLP Evaluations) This Section 1s for
determining both percent solids and the extraction fluid (to be used in the
procedure where volatiles are not involved). This determination 1s performed on
a separate sample. Once this determination has been performed, another sample
taken earlier is used for the next procedure. The procedure which 1s used at
this point depends on whether or not the sample contains volatile contaminants.
7.0 (8.0) Replace 75g sample requirement with "Enough sol Ids should be
generated for extraction such that the volume of TCLP extract will be sufficient
4
to support all of the analyses required. If the amount of extract generated by
the performance of a single TCLP extraction will not be sufficient to perform
all of the analyses to be conducted, it is recommended that more than one
extraction be performed and that the extracts from each extraction be combined
and then allquoted for analysis.
7.6 (8.6) Add: Centrifugation is to be used only as an aid to filtration. If
used, the liquid should be decanted and filtered followed by filtration of the
solid portion of the waste through the same filtration system.
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8.0 (9.0) Add: Any manipulation of the waste, the extract, or the initial
liquid phase should be done while cold (i.e., 4 degrees C), to minimize loss of
volatiles.
8.12 (9.13) Change the last sentence to read: All extract shall be filtered
and collected if the TEDLAR bag 1s used, if the extract is multi-phasic, or if
the waste contained an initial liquid phase (see Steps 4.6 and 9.1).
(10.3) Addition of the matrix spike should occur once the TCLP extract has been
generated, (i.e., should not occur prior to the performance of the leaching
step).
9.5 (10.6) Add: Samples must undergo TCLP extraction within the following time
period after sample receipt: Volatiles, 14 days; semi-volatiles, 40 days;
Mercury, 28 days; and other metals, 180 days. Extraction of the solid portion
of the waste should be initiated as soon as possible following initial
solid/liquid separation.
B. Changes Made to TCLP as a Result of Public Comments on the June 13, 1986,
Proposal
EPA has made additional technical and procedural changes to the TCLP as a direct
result of the public comments. These changes are listed below.
2.2 The first sentence of this step 1s changed to: "For wastes comprised of
solids or for wastes containing significant amounts of solid material, the
particle-size of the waste 1s reduced (if necessary). The liquid phase, if any,
is separated from the solid phase and stored for later analysis."
4.2.1 Add: This device 1s for use only when the waste 1s being tested for the
mobility of volatile constituents (see Table 1).
4.3 Add: It is recommended that all filtrations be performed 1n a hood.
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4.3.2 Add to the description of the filter holder: Vacuum filtration 1s only
recommended for wastes with low solids content (<103>) and for highly granular
(liquid containing) wastes. All other types of wastes should be filtered using
positive pressure filtration.
4.3.3 Add: Devices made of high-density polyethylene (HOPE), polypropylene, or
polyvinyl chloride may be used only when evaluating the mobility of metals.
5.1 Changed to Reagent Water, which is then defined.
5.5 Glacial acetic acid (HOAc) ACS Reagent grade
5.6.2 Change NOTE to: It is suggested that these extraction fluids be
monitored frequently for impurities. The pH should be checked prior to use to
ensure that these fluids are made up accurately.
6.2 New Section: At least two separate representative samples of a waste
should be collected. If volatile organlcs are of concern, a third sample should
be collected. The first sample 1s used 1n several preliminary TCLP evaluations
(e.g. to determine the percent solids of the waste; to determine 1f the waste
contains insignificant solids (i.e. the waste is Its own extract after
filtration); to determine if the solid portion of the waste requires particle
size reduction; and to determine which of the two extraction fluids are to be
used for the non-volatile TCLP extraction of the waste).
6.4 (6.5) Change "care must be taken to ensure these (i.e., volatiles) are hot
lost" to "care should be taken to minimize the loss of volatiles."
7.0 - 7.17 Becomes 8.0 - 8.15: Procedure when volatiles are not involved
7.7 (7.1.7) Add: NOTE: If waste material (>1% of the original sample weight)
has obviously adhered to the container used to transfer the sample to the
filtration apparatus, determine the weight of this residue and subtract it from
the sample weight determined in step 7.1.5 to determine the weight of the waste
sample that will be filtered.
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7.10 (7.2.2) Add: Until two successive weighings yield the same value within +
or - 1%.
7.10.2 (7.2.2) Add NOTE: It is recommended that the drying oven be vented to a
hood or appropriate device.
7.13 (8.9) Change to: Quantitatively transfer the solid material into the
extraction vessel, including the filter used to separate the initial liquid from
the solid phase.
7.13 (8.11) Change the length of time of the extraction from 18 hours to 18 +
or - 2 hours. Indicate that the temperature "22 + or - 3 degrees C" is air
temperature.
7.14 (8.12) Add: For the final filtration of the TCLP extract, the glass fiber
filter may be changed if necessary to facilitate filtration.
7.16 (8.14) Change to: The extract should be Immediately aliquoted for analysis
and properly preserved. (Metals aliquots must be acidified with nitric acid to
pH
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8.2 (9.2) Add: Adjust the piston within the ZHE body to a height that will
minimize the distance the piston will have to move once the ZHE is charged with
sample.
8.5 (9.6) Add: The means used to effect particle size reduction must not
generate heat in and of itself.
8.14 (9.15) Change - "determine the volume of the individual phases (to 0.1
ml)" to "determine the volume of the individual phases (to + or - 0.5%)."
9.0 - 9.5 Moves to Section 10.0 - 10.5.
9.2 (10.2) Add specification that extraction fluid #1 1s to be used for the
method blank.
9.4 (10.5) Change "for each waste type" to "for each analyte".
TCLP Flow Chart - Add arrowheads.
C. Changes Proposed in May 24, 1988, FRN
Section numbers refer to the TCLP (Method 1311) as finalized for use in the Land
Disposal Restrictions program on November 7, 1986, 51 FR 40643-40652.
Figure 1 - Flow chart has been revised
Table 2 - Environmental Machine and Design, Inc., andMillipore Corp. are added
as suppliers of rotary agitations apparatuses.
Table 3 - Lars Lande Mfg. is added as a supplier of Zero Headspace Extrator
Vessels.
Table 5 - Millipore and Nucleopore are added as suppliers of suitable filter
material.
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REFERENCES
1. Brown et . Mobility of Organic Compounds from Hazardous Wastes. NTIS
PB 83 163-956, 1983. (Brown et al., 1983).
2. Electric Power Research Institute (EPRI). Round-Robin Evaluation of
Regulatory Extraction Methods for Solid Wastes, EA-4740, Research Project
2485-8, Interim Report, December 1986. (EPRI, 1986).
3. Energy Resources Co. (ERCO). Filtration of Various Wastes Using Various
Filter Media. USEPA Contract 68-01-7075. April, 1985. (ERCO, 1985).
4. Energy Resources Co. (ERCO). Extraction Fluid Study and Development of
An Alkalinity Test for the Toxicity Characteristic Leaching Procedure,
USEPA Contract 68-01-7075, February 1986. (ERCO, 1986).
5. Francis, C. W. et al. Mobility of Toxic Compounds from Hazardous Wastes.
NTIS PB 85-117034. August 1984. (Francis et al., 1984).
6. Francis, C. W., and M. Maskarlnec. Field and Laboratory Studies in
Support of a Hazardous Waste Extraction Test, Oak Ridge National
Laboratory Report No. 6247, February 1986. (Francis and Maskarinec,
1986).
7. Klmmell, T. A., and D. Friedman. "Model Assumptions and Rationale Behind
the Development of EP-III". Hazardous and Industrial Solid Waste
Testing: Fourth Symposium. ASTM STP 886, J.K. Petros, Jr., W.J. Lacy,
and R.A. Conway, Eds. American Society for Testing and Materials, 1984.
(Kirnmell and Friedman, 1984).
8. Lancy International. Inter-Industry Collaborative Study of the Toxicity
Characteristic Leaching Procedure, September 1986. (Lancy, 1986).
9. Prange, N., and W. Garvey. "The Impact of Particle Size on TCLP
Extraction of Cement-Stabilized Metallic Wastes". Proceedings of the
Symposium on Waste Testing and Quality Assurance. USEPA, 1988. (Prange
and Garvey, 1988).
10. S-Cubed. Collaborative Study of the Toxicity Characteristic Leaching
Procedure (TCLP). Interim Report SSS-R-87-8199. EPA Contract 68-03-
1958. September 1986. (S-Cubed, 1986a).
11. S-Cubed. Collaborative Study of the Toxicity Characteristic Leaching
Procedure (TCLP). Draft Final Report. SSS-R-87-8199. EPA Contract 68-
03-1958. November 1986. (S-Cubed, 1986b).
12. S-Cubed. Single Laboratory Testing of the Toxicity Characteristic
Leaching Procedure (TCLP) Using Conventional Apparatus. SSS-R-86-7821.
EPA Contract 68-03-1958. February 1986. (S-Cubed, 1986c).
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13. S-Cubed. Precision Evaluation of the Toxicity Characteristic Leachina
Procedure (TCLP) fcr Volatile Contaminants. Final Report SSS R Rfi
EPA Contract 68-01-/256. July 1986. {S-Cubed, 1986d). oo-ouac.
14. USEPA. Background Document, Section 261.24, Characteristic of
Extraction Procedure Toxicity. NTIS PB 81-185027. Mav 1980 Cikfda
1980). ' 1 A'
15. USEPA. Background Document: Resource Conservation and Recovery Act
Subtitle C--Hazardous Waste Management System, Section 3001-- '
Identification and Listing of Hazardous Waste. Toxicity Characteristic
Leaching Procedure (TCLP). Washington, DC. March 1986 (USEPA, 1986a).
16. USEPA. Background Document: Resource Conservation and Recovery Act
Hazardous and Solid Waste Amendments of 1984, Land Disposal Restrictions
Rule, Solvents and Dioxins. Toxicity Characteristic Leaching Procedure
(TCLP). November 7, 1986. (USEPA, 1986b)..
17. Warner, J.S., B.J. Hidy, G.A. Jungclaus, M.M. McKown, M.P, Miller, and
R.M. Riggin, "Development of a Method for Determining the Leachability of
Organic Compounds from Solid Wastes," 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. (Warner et
al., 1981).
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