California Code of Regulations › Title 23 - Waters › Division 3 - State Water Resources Control Board and Regional Water Quality Control Boards › Chapter 15 - Discharges of Hazardous Waste to Land › Article 10 - Definitions › Appendix I - Step-By-Step Guide to Clay Liner-Leachate Compatibility Testing

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
[FN1]
Presented by David Anderson and Gordon Evans of K. W. Brown
					 and Associates as part of the Soil Liners workshop, Permit Writers Training
					 Program, conducted by EPA in San Francisco, California, November 14-17,
					 1983.
There is currently no standard scheme for evaluating clay
					 liner-leachate compatibility. Following is a suggested step-by-step method for
					 evaluating compatibility.
Step 1: Obtain Representative Waste Samples
Guidance
The first step in analyzing waste-liner compatibility is to
					 obtain a representative sample of the waste to be stored. If any liquids are
					 present in the waste, make sure that the liquids do not drain out of the waste.
					 The sample must contain these liquids to adequately indicate waste liner
					 compatibility.
Method
Several methods for obtaining samples of hazardous wastes
					 are discussed in Section One of Test Methods for Evaluating Solid Waste (EPA,
					 1982b). Data supplied on the wastes should include the following:
a. EPA Hazardous Waste Numbers (D, F, and K numbers)
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
b. Physical Class of Waste (aqueous-inorganic;
					 aqueous-organic; organic, or solid, sludge, or slurry) Aqueous-inorganic (AI)
					 and aqueous-organic (AO) are classes of waste in which water is the solvent
					 (predominant liquid), and the solutes are mostly inorganic and organic,
					 respectively. Organic (O) is the class of waste in which the predominant
					 liquids are organic, and the solutes are mostly other organic chemicals
					 dissolved in the organic solvent. Solids, sludges, and slurries (S) are wastes
					 high in solids such as tailings, settled matter, or filter cakes.
c. Waste Stream Description (describe the production and
					 waste treatment processes from which the waste stream is generated)
d. __________ Percent Solids (wet weight basis) (determine
					 by drying waste at 10°C for 24 hours)
Step 2: Extract Primary Leachate
Guidance
The primary leachate is the liquid that can be extracted
					 from the waste. It is collected and used to evaluate liner compatibility with
					 liquids present in a waste. If there is more than one distinct immiscible phase
					 in the primary leachate, collect enough of each phase (approximately 5 liters
					 per primary leachate phase) to perform the compatibility testing with each
					 phase.
Method
The primary leachate is extracted from the waste by vacuum
					 filtration at 25°C and should be measured as a percentage of the total
					 waste on a wet weight basis. Attach a large capacity porcelain buchner funnel
					 to a large capacity sidearm flask. Place a rapid flow rate, glass fiber filter
					 circle in the buchner funnel. Wet the filter with a few drops of water, and
					 load the buchner funnel with fresh waste. Connect the flask to an aspirator
					 pump and apply a vacuum to the waste for five minutes or until most of the
					 liquids are removed from the waste. Remove the solids from the buchner funnel,
					 place a clean filter circle in the funnel, wet the filter as before, and reload
					 the funnel with fresh waste. Repeat the above process until sufficient primary
					 leachate has been collected for testing (approximately five liters). If no
					 liquids are extractable from the waste, proceed with step three.
Step 3: Extract Secondary Leachate
Guidance
The secondary leachate is an aqueous extract of the waste.
					 It is collected and used to evaluate liner compatibility with leachate
					 generated by water percolating through the waste.
Method
The secondary leachate is collected by thoroughly mixing
					 the waste with just enough water to obtain the consistency of a saturated
					 paste. (A saturated paste should be thick enough so that the waste barely flows
					 together into a hole made in the paste with a spatula). Filtrate collected from
					 vacuum filtration of the saturated paste is the secondary leachate to be used
					 in the liner-leachate compatibility tests.
Secondary leachate can be extracted from the saturated
					 paste in the same manner in which primary leachate is removed from
					 liquid-bearing wastes. Enough saturated paste should be subjected to vacuum
					 filtration to collect approximately five liters of secondary leachate. Do not
					 reuse waste samples for the collection of additional leachate, as this would
					 result in an excessively diluted leachate.
Step 4: Analyze Primary Leachate
Guidance
If the waste contained a primary leachate, it should be
					 analyzed to establish the type and concentration of the organic liquids
					 present. Some primary leachate may contain two distinct immiscible phases. It
					 is advisable to analyze each phase separately. Subsequent routine analysis
					 should be performed to assure that leachate composition has not changed in a
					 way that would affect liner performance. While the initial analysis should be
					 definitive with regard to the liquids and solutes present in the leachate, the
					 routine analysis need only confirm that leachate composition has not
					 appreciably changed.
Method
Permit applicants may be able to find analyses of similar
					 wastes in company files, state regulatory agency files, or in the analyses of
					 wastes compiled by EPA (EPA, 1980a; EPA, 1980b). It should be noted, however,
					 that it is leachate analyses that will ultimately be needed for use in
					 characterizing liner-leachate compatibility. The following information on the
					 primary leachate should be collected.
a. __________ percent Filtrate (wet weight basis) that
					 would be removed from waste by vacuum filtration (at 25°C)
b. Predominant liquid constituents as a percentage of total
					 primary leachate (filtrate) (indicate to 0.1 percent)
__________
							 percent
___________________________Water
__________
							 percent
___________________________
__________
							 percent
___________________________
__________
							 percent
___________________________
__________
							 percent
___________________________
c. Predominant solutes as gL-1
					 of total primary leachate (indicate to 0.1
					 gL-1)
__________
							 gL-1
___________________________
__________
							 gL-1
___________________________
__________
							 gL-1
___________________________
__________
							 gL-1
___________________________
__________
							 gL-1
___________________________
A two-step method can be used to analyze primary leachate.
					 First, fractional distillation can be used to separate and quantify the liquids
					 according to the temperature at which each fraction is removed from the bulk
					 liquid. The mass of each fraction as a percent of the total primary leachate
					 can then be determined gravimetrically. Secondly, each fraction obtained can be
					 identified by gas chromatography and, if necessary, confirmed by mass
					 spectrometry.
These methods are discussed in Section Eight of Test
					 Methods for Evaluating Solid Waste (EPA, 1982b). After these initial detailed
					 analyses, subsequent routine analyses may be limited to the first step of the
					 method.
Primary Leachate pH = ___________________________
Primary Leachate EC = ___________________________
The pH of the primary leachate can be determined
					 electrometrically using a saturated paste and a glass electrode in combination
					 with a reference potential or a combination electrode. The electrical
					 conductivity (EC) of the primary leachate is determined by using a saturated
					 paste extract and a self-contained conductivity meter, such as a wheatstone
					 bridge-type or equivalent.
Step 5: Analyze Secondary Leachate
Guidance
The secondary leachate is an aqueous-based liquid and may
					 have the following types of solutes: acids, bases, salts, and organic
					 chemicals. This leachate must be analyzed to determine the concentration of the
					 solutes.
Method
The following information is needed to characterize
					 secondary leachate. Some of the information may be collected by methods that
					 are similar to those used for the primary leachate.
a. __________percent Filtrate (wet weight basis) that could
					 be removed from the waste made into a saturated paste by addition of distilled
					 water.
b. Predominant solutes as gL-1
					 of total primary leachate (indicate to 0.1
					 gL-1)
__________
							 gL-1
___________________________
__________
							 gL-1
___________________________
__________
							 gL-1
___________________________
__________
							 gL-1
___________________________
__________
							 gL-1
___________________________
c. Secondary Leachate pH =
					 ___________________________
Secondary Leachate EC = ___________________________
The types and concentration of the solutes present in the
					 leachate can be determined as follows:
Salts
may be initially characterized by
					 atomic absorption spectrophotometry and electrical conductivity. The method for
					 measuring EC is discussed above and the methods for atomic absorption
					 spectrophotometry for various inorganics are found in Section Seven of Test
					 Methods for Evaluating Solid Waste (EPA, 1982b). Subsequent routine analysis
					 may usually be limited to EC unless this measurement indicates the leachate is
					 significantly different from that originally analyzed.
Acids and Bases may be satisfactorily characterized by
					 measuring the pH of the leachate using a standard pH meter and electrodes, as
					 described for the primary leachate.
Organic Solutes can be quantified by determining the total
					 organic carbon in the leachate by converting organic carbon in the sample to
					 carbon dioxide (CO2) by catalytic combustion or wet
					 chemical oxidation. The CO2 formed can be measured
					 directly by an infrared detector or converted to methane
					 (CH4) and measured by a flame ionization detector (EPA,
					 1979). The amount of CO2 or CH4
					 is directly proportional to the concentration of carbonaceous material in the
					 sample. If low molecular weight organics are present in the leachate at
					 concentrations of parts per thousand or greater, it may be advisable to use the
					 fractionation and analysis technique described above for the primary leachate.
					 For more dilute solutions, it may be necessary to extract the organic
					 constituents and analyze them by liquid chromatograpy and gas chromatography.
					 These are discussed in Section Eight of
Test Methods for Solid
					 Waste
(EPA, 1982b).
Step 6: Characterize the Clay Liner Guidance
Characterization should include the determination of
					 effective pore volume and permeability of the clay liner.
Method
Characterization of a clay liner will not, in itself,
					 reveal if a liner has all the appropriate properties to prevent failure. This
					 characterization can, however, establish the baseline permeability and
					 effective pore volume values with a standard aqueous leachate (0.01 N
					 CaSO4) and nonattenuated ion (bromide), respectively.
					 These baseline values can be compared with the values obtained with the
					 leachates of a waste. Suitable methods for analyzing soil physical properties
					 are available in the latest edition of ASTM Standards (part 19: Natural
					 Building Stones; Soil and Rock), in Black (1965), or in most soil testing
					 manuals. Determination of bromide breakthrough can be accomplished by using a
					 bromide selective electrode to analyze permeameter outflow. The following
					 information should be determined for the clay liner.
a. Particle size distribution and clay minerology
1. __________percent Sand ( >50 µm, dry wt.
					 basis)
2. __________percent Silt (50-2.0 µm, dry wt.
					 basis)
3. __________percent Clay ( <2.0 µm dry wt.
					 basis)
4. __________percent of Clay that is coarse (2.0-0.2
					 µm, dry wt. basis)
5. Predominant coarse Clay minerals
__________ percent ___________________________
__________ percent ___________________________
__________ percent ___________________________
6. __________percent of Clay that is fine (0.2 µm,
					 dry wt. basis)
7. Predominant fine Clay minerals
__________ percent ___________________________
__________ percent ___________________________
__________ percent ___________________________
b. Physical properties
1. __________ g cm-3-particle
					 density
2. __________ percent in-place (as compacted) water content
					 (dry wt. basis)
3. __________ g cm-3-place (as
					 compacted) density (dry wt. basis)
4. __________ percent pore space (percent of total liner
					 volume)
5. Permeability to an aqueous solution of 0.02 N
					 CaSo4 or CaCL2 after percolation
					 of:
0.5 pore volume ________________________________________
					 cm/sec
1.0 pore volume ________________________________________
					 cm/sec
1.5 pore volume ________________________________________
					 cm/sec
2.0 pore volume ________________________________________
					 cm/sec
6. Pore volume values for Bromide breakthrough
__________percent Bromide at 0.1 pore volume
__________percent Bromide at 0.2 pore volume
__________percent Bromide at 0.3 pore volume
__________percent Bromide at 0.4 pore volume
__________percent Bromide at 0.5 pore volume
__________percent Bromide at 0.6 pore volume
__________percent Bromide at 0.7 pore volume
__________percent Bromide at 0.8 pore volume
__________percent Bromide at 0.9 pore volume
__________percent Bromide at 1.0 pore volume
The permeability of the clay liner should first be
					 evaluated using a standard leachate (such as 0.01 N
					 CaSO4 or CaCl2). After the
					 permeability has stabilized, the effective pore volume can be estimated by
					 spiking the standard leachate with bromide and monitoring the breakthrough of
					 bromide in the permeameter outflow. Assuming that a clay liner is presaturated
					 with clean water, nonattenuated leachate constituents (e.g., bromide) will be
					 present in the outflow from the permeameter after passage of leachate equal to
					 approximately 50 percent of the volume represented by one effective pore
					 volume.
Step 7: Determine Compatibility of the Proposed Clay Liner
					 with the Expected Leachates
Guidance
A substantial body of data suggests that concentrated
					 organic liquids may significantly degrade the performance of clay liners;
					 consequently, clay liner-waste leachate compatibility tests should be conducted
					 to verify that leachates will not move beyond the clay liner during the active
					 life of the facility. These organic liquids include polar, nonpolar, basic, and
					 acidic organic liquids. In all probability, organic liquids will degrade clay
					 liner performance to an extent that these liners will have either a short
					 lifetime or a large thickness requirement. There are also substantial data
					 indicating that either strong aqueous salt, acidic, or basic solutions may
					 degrade clay liner performance. It should be noted, however, that acids and
					 bases can be neutralized, and certain treated clays may resist degradation upon
					 exposure to many strong aqueous salt solutions.
Basic and nonpolar organic liquids have shown the potential
					 to significantly decrease the effective pore volume of clay liners. Polar
					 organic liquids appear to degrade clay liner permeability to a greater extent
					 than they initially degrade effective pore volume. There is substantial
					 evidence that a wide range of organic liquids may degrade clay liner
					 effectiveness.
Method
The permeability and lowest pore volume at which waste
					 constituents appear in permeameter outflow should be determined with both the
					 primary and secondary leachates of the wastes if these solutions are
					 appreciably different. These values should be compared with the baseline values
					 previously determined to see if the leachates are likely to degrade the ability
					 of a clay liner to meet the leachate containment performance standard. Whenever
					 either organic liquids or concentrated solutes are present in leachates, it is
					 suggested that clay liners be tested by passing at least two full pore volumes
					 of the leachates through the liner. If the primary leachate of a waste contains
					 two or more immiscible phases, it is advisable to test each phase separately
					 and to test the phases sequentially on the same clay core. The leachates used
					 in the permeability tests should be at the highest concentration at which they
					 would ever be while in contact with the clay liner. For constant head
					 permeability tests, the following equation may be used:
K = V/AtH
where:
K = permeability constant (cm
					 sec-1);
t = time (sec);
v = volume of leachate passed through the soil
					 (cm3);
A = cross sectional area of liquid flow
					 (cm2); and
H = hydraulic gradient or (h + L)/L where:
h = hydraulic head (cm of H2O)
					 and
L = length of soil column (cm)
For failing head permeability tests, the following
					 permeability equation can be used (Olson and Daniel 1981):
Click
					 here to view image
where: K = permeability constant (cm
					 sec-1)
a = cross sectional area of the buret
					 (cm2)
A = cross sectional area of the soil
					 (cm-2)
L = length of the soil (cm)
t = elapsed time from 5(0) to t(1)(sec)
h(0) = height of water in standpipe above the discharge
					 level at t(0)(cm)
h(1) = height of water above the discharge level at time
					 t(1)(cm)
This equation can be arranged as follows:
Click
					 here to view image
Thus, the slope of the line obtained by plotting ln
					 hydraulic head versus time may be used to determine the permeability
					 constant:
Click
					 here to view image
Permeability (k) should be plotted along the Y-axis, while
					 the cumulative pore volume at which each permeability is obtained should be
					 plotted along the X-axis. Incremental pore volumes are obtained by dividing the
					 volume of leachate (v) by the total pore volume of the compacted soil specimen
					 used in the test. Total pore volume of a specimen is obtained as
					 follows:
total pore volume = pAL
where porosity (p) is multiplied by the total volume (AL)
					 of the soil specimen. Porosity is determined as follows:
Click
					 here to view image
where the bulk density, or unit weight (BD) is divided by
					 the particle density (Gs).
If elevated hydraulic gradients are to be used and there is
					 a failure in the clay liner being tested, a rough estimate of the time to
					 failure can be made by rearranging Darcy's law so that time is isolated as
					 follows:
Click
					 here to view image
where: ti1= laboratory test time
					 increment (sec)
H1 = hydraulic gradient used in the
					 laboratory (unitless)
To convert laboratory time to the corresponding time in the
					 field, the maximum hydraulic gradient that will occur in the field
					 (H2) may be substituted for the value used in the
					 laboratory (H1) as follows:
Click
					 here to view image
where: ti2= field time increment
					 (sec)
H2= maximum hydraulic gradient in
					 the field (unitless)
The field time values obtained from the beginning of the
					 test until waste constituents appear in the permeameter outflow should be
					 summed together. This total time value should then be multiplied by the ratio
					 of the field liner thickness to the laboratory liner thickness to arrive at the
					 useful life of the clay liner as follows:
Click
					 here to view image
where: T = useful life of the clay liner (sec)
n = time increment where leachate constituents are first
					 detected permeameter outflow
Y = (thickness of field liner (cm))/(thickness of
					 laboratory liner (cm))
a. Permeability to primary leachate (where two or more
					 distinct immiscible primary leachates are present, test the solutions
					 separately).
0.1 pore volume
							 ________________________________________ cm/sec
0.2 pore volume
							 ________________________________________ cm/sec
0.3 pore volume
							 ________________________________________ cm/sec
0.4 pore volume
							 ________________________________________ cm/sec
0.5 pore volume
							 ________________________________________ cm/sec
0.6 pore volume
							 ________________________________________ cm/sec
0.7 pore volume
							 ________________________________________ cm/sec
0.8 pore volume
							 ________________________________________ cm/sec
0.9 pore volume
							 ________________________________________ cm/sec
1.0 pore volume
							 ________________________________________ cm/sec
1.1 pore volume
							 ________________________________________ cm/sec
1.2 pore volume
							 ________________________________________ cm/sec
1.3 pore volume
							 ________________________________________ cm/sec
1.4 pore volume
							 ________________________________________ cm/sec
1.5 pore volume
							 ________________________________________ cm/sec
1.6 pore volume
							 ________________________________________ cm/sec
1.7 pore volume
							 ________________________________________ cm/sec
1.8 pore volume
							 ________________________________________ cm/sec
1.9 pore volume
							 ________________________________________ cm/sec
2.0 pore volume
							 ________________________________________ cm/sec
b. Permeability to secondary leachate
0.1 pore volume
							 ________________________________________ cm/sec
0.2 pore volume
							 ________________________________________ cm/sec
0.3 pore volume
							 ________________________________________ cm/sec
0.4 pore volume
							 ________________________________________ cm/sec
0.5 pore volume
							 ________________________________________ cm/sec
0.6 pore volume
							 ________________________________________ cm/sec
0.7 pore volume
							 ________________________________________ cm/sec
0.8 pore volume
							 ________________________________________ cm/sec
0.9 pore volume
							 ________________________________________ cm/sec
1.0 pore volume
							 ________________________________________ cm/sec
1.1 pore volume
							 ________________________________________ cm/sec
1.2 pore volume
							 ________________________________________ cm/sec
1.3 pore volume
							 ________________________________________ cm/sec
1.4 pore volume
							 ________________________________________ cm/sec
1.5 pore volume
							 ________________________________________ cm/sec
1.6 pore volume
							 ________________________________________ cm/sec
1.7 pore volume
							 ________________________________________ cm/sec
1.8 pore volume
							 ________________________________________ cm/sec
1.9 pore volume
							 ________________________________________ cm/sec
2.0 pore volume
							 ________________________________________ cm/sec
c. Pore volume values for breakthrough to two mobile waste
					 constituents (waste constituent in eluate as percent of constituent
					 inleachate).
1. Constituent No. 1
__________percent of 0.1 pore
							 volume
__________percent at 1.1 pore volume
__________percent of 0.2 pore
							 volume
__________percent at 1.2 pore volume
__________percent of 0.3 pore
							 volume
__________percent at 1.3 pore volume
__________percent of 0.4 pore
							 volume
__________percent at 1.4 pore volume
__________percent of 0.5 pore
							 volume
__________percent at 1.5 pore volume
__________percent of 0.6 pore
							 volume
__________percent at 1.6 pore volume
__________percent of 0.7 pore
							 volume
__________percent at 1.7 pore volume
__________percent of 0.8 pore
							 volume
__________percent at 1.8 pore volume
__________percent of 0.9 pore
							 volume
__________percent at 1.9 pore volume
__________percent or 1.0 pore
							 volume
__________percent at 2.0 pore volume
2. Constituent References:
Black, C. A. (ed.) (1965).
Methods of Soil
					 Analysis, Part 1. Physical and Mineralogical Properties Including Statistics of
					 Measurement and Sampling.
Am. Soc. Agron., Madison, Wisconsin. 770p.
					 EPA. (1979).
Methods for Chemical Analysis of Water and
					 Wastes.
EPA 600/4-79-020 (PB 297-686/8BE).
EPA. (1980a).
Listing of Hazardous Waste.
RCRA, Office of Solid Waste, Washington, D. C. Section
					 261.20 through Section
					 261.21. May 19, 1980.
EPA. (1980b.)
Hazardous Waste Land
					 Treatment
. Written for U.S. EPA by K. W. Brown and Associates, Inc.
					 EPA, Cincinnati, Ohio. SW-874.
EPA. (1982b).
Test Methods for Evaluating Solid
					 Waste.
U.S. EPA Office of Solid Waste and Emergency Response.
					 Washington, D. C. SW-846.