United States
Environmental Protection
Agency
Municipal Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-83-046 Aug. 1983
v>ERA Project Summary
Field Verification of Liners from
Sanitary Landfills
Liner specimens from three existing
landfill sites were collected and ex-
amined to determine the changes in
their physical properties overtime and
to validate data being developed through
laboratory research. Samples examined
included a 15-mil PVC liner from a
sludge lagoon in New England, a 30-
mil PVC liner from a landfill in New
York State, and four liners from a land-
fill test site in Boone County, Kentucky-
chlorosurfonated polyethylene (CSPE),
low-density polyethylene (LDPE), clay,
and chlorinated polyethylene (CPE),
low-density polyethylene (LDPE). clay.
and chlorinated polyethylene (CPE).
The 15-mil PVC liner from the New
England sludge lagoon lost plasticizers
whether it was exposed to sludge only,
weather only, or both. But the most
severe loss of plasticizer and stiffening
was exhibited by samples that had
been exposed to weather only.
The 30-mil PVC liner from the New
York landfill had stiffened and probably
lost plasticizer after exposure to weath-
er for 3 years. But the material was still
extensive and had not become brittle,
as is often the case with exposed PVC
liners.
The remaining four liners from Boone
County, Kentucky, came from two dif-
ferent test cells. The CSPE, LDPE, and
clay liners were all from Test Cell 1.
The CSPE liner was swollen and soft
and had adsorbed considerable amounts
of leachate after 9 years of exposure to
attenuated leachate. Nonetheless, its
properties were relatively normal for
CSPE material. The LDPE liner appeared
to be unaffected by its 9 years of
exposure to full-strength leachate.
These samples showed little swelling
and normal properties for a 6- to 7-mil
LDPE liner. The clay liner was shown
to have contained the leachate effec-
tively. No cracking, channeling, or un-
usual changes in texture or consisten-
cy were noted. The CPE liner from Test
Cell 2 showed significant absorption
of the leachate it had contained, but its
properties were relatively good. CPE
samples that had been exposed to
weather only for 9 years showed signifi-
cantly higher tensile strength, moduli,
and puncture resistance than did the
leachate-exposed samples.
This Project Summary was developed
by EPA's Municipal Environmental Re-
search Laboratory, Cincinnati, OH, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
When municipal solid waste (MSW) is
landfilled, ground and surface waters must
be protected from leachates-liquid that
has percolated through the waste and has
become contaminated with extracted, dis-
solved, or suspended materials. The use
of impervious barriers to intercept and
control leachate offers a promising means
of reducing or eliminating such pollution,
and it is recommended by the U.S. Environ-
mental Protection Agency (EPA) for con-
sideration as a control mechanism.
Containment systems have traditionally
been lined to prevent the excessive seep-
age of liquids into the ground. Clay, wood,
concrete, asphalt and metal linings were
used in the past in a wide variety of
applications. And in the last 30 years,
synthetic impervious lining materials have
been developed Among these are polye-
thylene (PE), polyvinyl chloride (PVC),
chlorosulfonated polyethylene (CSPE),
butyl rubber, high density polyethylene
(HOPE), and various asphalt cement mix-
tures.
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A major concern with liners is the possi-
bility of their degradation after prolonged
exposure to leachate, which might chemi-
cally or physically attack liner materials.
Unfortunately, no method of laboratory
testing presently exists to predict the field
service life of various liners. Strong cir-
cumstantial evidence indicates that liner
life can exceed 20 years: Research to date
shows only minimal physical changes in
liner materials exposed to landfill leachate.
More study is needed, however.
The primary objective of this project was
to obtain specimens of liners from existing
landfills to determine the changes in their
physical properties as a function of age
and to validate data being developed through
laboratory research. Specifically, the pro-
gram was to achieve the following goals:
1. Determine the nature, extent, and
causes of any changes in the liners
after prolonged exposure to the land-
fill environment
2. Improve the ability to select liners by
developing information on their
strengths and weaknesses under a
variety of conditions.
3. Assist regulatory agencies by pro-
viding information that could be used
to develop site location and perform-
ance standards for waste disposal
permit programs.
The project consisted of the following
three tasks: (1) Obtaining liner samples
and repairing the liner material after sample
removal; (2) testing and evaluating the
samples, and (3) comparing original liner
material with the removed samples.
Methods and Materials
Site Select/on
Thirty candidate sites were originally
identified as possible choices for study.
The criterion for the ideal test site was that
it should have complete data and records
available in the following categories:
1. Liner design and installation tech-
niques
2. Methods of site operation
3. Type, age, and thickness of wastes in
the landfill
4. Occurrence, quantity, and character
of leachate
5. Soils, geology, and groundwater.
The original scope of work called for
samples of several types of liners (clay,
asphalt and polyvinyl chloride) from at
least four landfills. Unfortunately, how-
ever, most operators of the 30 selected
sites declined to participate in the study
because of legal considerations. The final
field testing program was therefore re-
stricted to liner materials obtained from
three sites:
1. A New England sludge lagoon with a
15-mill PVC liner,
2. A landfill in New York State with a
30-mil PVC liner, and
3. An EPA field site in Boone County,
Kentucky (BCFS), with a chlorosul-
fonated polyethylene (CSPE) liner, a
low-density polyethylene (LDPE) liner,
a clay liner, and a chlorinated poly-
ethylene (CPE) liner.
Samp/ing
The sampling program was designed
with three objectives: (1) To obtain samples
of the various in-place liner materials, (2)
to sample indigenous soils beneath the
liner, and (3) to repair the liner to preclude
escape of leachate as a result of the
temporary interruption of liner integrity.
Samples of similar soils beyond the in-
fluence of the landfill were also collected
and analyzed for purposes of background
comparisons.
Testing and Evaluation
The testing and evaluation methods
selected were tailored to the two types of
liner materials to be sampled-clayed and
polymeric. Characteristics and properties
of clay liners were to be compared with
those for background soils to determine
the nature of physical and mechanical
changes at depth. Testing of polymeric
materials included determinations of per-
meability, thickness, tensile strength and
elongation at break, hardness, tear strength,
creep, water absorption or extraction,
puncture resistance, and density.
Chemical tests on soil samples beneath
the liners included analyses for pH, Hg, Pb,
Zn, Cd, Fe, Cl, COD, Na, NH4, K, and Mg.
This testing was designed to develop ab-
sorption data. Underlying soils were also
subjected to physical tests for permeability,
density and voids, water swell, and com-
pressive strength.
Results and Procedures
New England Sludge Lagoon
(SI)
The sludge lagoon at the solid waste
disposal facility in New England covers
approximaterly 1.25 ha (3.1 acres) and is
5 m (16 ft) at its deepest The lagoon is
completely lined with a 15-mil PVC liner.
Sludge disposed of at the site consists of
approximately 85 percent water and 15
percent syspended solids. A high pH of
10 to 11 is due to a high lime and ferric
chloride content which along with other
toxic chemical conditioning agents, con-
stitutes up to 40 percent of the total filter
caka
Samples were collected from weathered
and sludge-exposed portions of the liner
on two major site visits. Results for the
weathered samples (Table 1) show a con-
siderable variation in properties. Those
portions that had been exposed to the
weather showed a loss of plasticizer and a
stiffening. One sample that was taken
from a portion of the liner that had been
stretched tightly across a boulder and
exposed to the weather had a very low
elongation (extending only 8 percent) and
a thickness of only 11.5 mils (compared
with the probable 1 5 mils of the original
material). The extractables were still rela-
tively high and might contain low-molecular-
weight degradation products of the PVC.
These data indicated strongly that a PVC
liner should be covered and probably
should be thicker than 15 mils if there is a
possibility that the cover might be re-
moved.
Samples of sludge-exposed liner were
obtained from an area of the lagoon where
sludge was being removed. None of the
samples were taken from beneath the
maximum depth of the sludge where an-
aerobic conditions were assured. Three of
the samples had been covered with soil or ^
with sludge, and the fourth was taken ^
from the east berm and had been removed
recently from the area where the sludge
excavation was taking place. All of the
samples were flexible, but to various de-
grees. Test results showed that only the
weathered sample (from the berm) had
lost considerable elongation. Elongations
and extractables of the samples varied
considerably and indicated that plasticizers
were lost during exposure to the sludge
even when the liner had not been exposed
to the weather. A calcium carbonate
deposit was found to be building up on the
liner.
•Soil samples from beneath the lagoon
liner were analyzed for chemical constitu-
ents indicative of leachate that might have
penetrated the liner. Although the results
showed elevated concentrations of nearly
all constituents when compared with back-
ground sample data, the evidence is not
sufficiently conclusive without additional
testing.
New York State Landfill (SII)
The New York State landfill (Sll) covers
about 2.4 ha (6 acres) of rolling and
wooded terrain in an area of predominantly
clay and sandy soils with intermittent ^
outcroppings of rocks. Precipitation aver- •
ages 11 7 cm (46 in.) throughout the year.
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Table 1. Properties
Property
Analyses.*
Volatile* (2 hr at W5°CI,%
Ash%
Specific gravity
Extractables, %
Physical properties
Thickness, mils
Breaking factor, ppi
Elongation at break. %
Tensile set, %
S- 100, ppi
S-200, ppi
Tear strength. Die C Ib
Hardness:
Duro A :
Instant reading
5-sec reading
Duro D:
Instant reading
5-sec reading
Puncture strength:
of 15- Mil PVC Liner Samples from Sludge Lagoon (SI)
Collected June
Direction Collected October 1 979. southwest side 1979 Berm
of test
—
—
—
—
—
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
_
...
—
_
Ml*
0.9-7.1
—
—
30.9-35.9
12.4
67.7
73.5
335
295
88
63
36.2
43.9
45.2
53.4
—
—
—
—
—
...
M2A
0.65
—
—
37.2
14.7
70.4
73.8
275
285
127
180
60.0
58.0
68.3
65.8
_
—
—
—
—
—
M2B M3
0.26 3.41
—
._
22.7 24.8
14.8 1 1.6
61.9 34.0
62.1 30.2
310 8
325 5
110 2
127 1
40.9
39.7
50.4
49.7
... _
—
—
—
—
—
M4A
0.28
—
—
32.5
75
42.4
37.2
310
300
92
97
28.4
25.9
34.1
31.2
...
_.
47.2
36.8
_
...
M4B
0.25
—
—
33.4
75
38.5
34.0
300
300
87
95
25.5
22.7
32.7
27.7
_
—
—
...
—
—
Thickness of specimen, mils — — — — — — —
Stress, Kg (Ib)
Elongation, cm (in.)
—
—
—
—
—
...
_.
„
—
...
Collected June 9. 1980
Northeast corner East berm
1A
5.44
5.74
1.27
32.11
16.5
48.6
38.5
290
270
83
54
29.7
26.0
38.6
33.8
6.7
5.8
83
81
40
33
16.3
13
(28.9)
1.9
(0.76>
1B-Z
8.15
4.35
1.31
28.99
15.0
41.6
44.4
225
225
86
114
33.8
35.5
41.4
42.3
6.5
6.8
87
86
49
44
J5.5
72.9
f28.3)
1.3
10.51)
1C
3.13
3.97
1.25
36.72
16.0
47.1
43.8
350
400
86
109
22.9
19.1
32.1
26.4
5.2
4.8
79
75
33
27
16.2
12.8
128.2)
2.3
10.93)
X*
8.46
5.83
7.32
25.84
76.0
38.9
38.2
770
775
707
97
36.7
34.9
—
—
7.0
6.6
87
87
57
46
76.0
9.6
121.1)
0.89
10.35)
'Sample number.
+Taken from excavation dike at the northeast comer of the lagoon.
t Solvent CH3OH + CCI*
The method of landfilling was to place
wastes in 3.1 -m (10-ft) lifts covered with
soil. No liquid or hazardous wastes were
accepted for disposal between 1976 (when
the landfilling commenced) and October
17, 1979, the date of the site visit
During the site visit a piece of the 30-
mil PVC liner was collected from the
surface near an exposed boulder. Results
of tests run on this sample indicate that
the sample had stiffened and probably lost
plasticizer during its exposure to weather.
The material was still extensible and had
not become brittle, as is often the case
with exposed PVC liner sheeting. Because
no test data existed for the original liner
material, no determination could be made
of changes in properties that occurred
during exposure.
Boone County Field Site (BCFS)
The BCFS is an experimental landfill
operated by EPA to determine landfill
performance. This 4-ha (10-acre) tract
sits on top of a ridge 5 miles west of the
City of Walton in Northern Kentucky. The
site contains a field-scale landfill andJour
smaller test cells. This study examines
clay and synthetic liners from the field-
scale landfill (TC-1) and from one of the
smaller test cells (TC-2D).
TC-1
From TC-1, samples were taken of a clay
liner, a chlorosulfonated polyethylene liner
(CSPE), and a low-density polyethylene
liner (LDPE). Figure 1 shows the relative
positions of these liners in the test cell.
The clay liner was composed of a slightly
sandy moderately plastic clay containing
limestone rock fragments up to 26 cm (10
in.) long. Liner thickness varied from 44 to
62 cm (17 to 24 in.). The clay was
classified as a CL by the Unified Soil
Classification System, with an average
liquid limit of 42 and a plasticity index of
20. Rock fragments lay parallel to the liner
surface. Average in-place dry density was
99 pcf, and average moisture content was
25 percent Permeability ranged from 4 to
5 x 10"7 cm/sec for in-place tests; in
laboratory tests, it was 2x10'8 cm/sec.
The liner was light brown-gray to a depth
of 31 to 36 cm (12 to 14 in.), where it
abruptly changed to a more natural orange-
tan for the remainder of its thickness. No
visual signs of cracking, channeling, or
unusual changes in texture or consistency
were noted in any of the excavations.
Chemical analyses of the clay liner in TC-1
indicated that it provided effective leachate
containment Some leachate had collected
below the clay liner, but this leakage
resulted from a small perforation in the
clay surface during cell preparation.
Four samples of synthetic liners were
collected from TC-1 -three CSPE and one
LDPE sample. Theunreinforced0.75-mm
(30-mil) CSPE sheeting had been in con-
tact with a small amount of dilute leachate
for 9 years, and the 0.15-mm (6-mil),
unpigmented LDPE had been in contact
with full-strength leachate for the same
period.
The CSPE samples exposed to leachate
had imprints of gravel and were swollen
and soft They had a small-scale rough
appearance similar to that of a nervy
compound after calendering. Seams had
blisters filled with fluid that appeared to be
essentially water. Substantial amounts of
the dilute leachate were absorbed by the
CSPE samples, with weights increased by
as much as 28.4 percent and volumes by
57 percent Ash values indicated a high
inorganic filler content Extractables (after
the volatiles were removed) were relatively
low, indicating either a relatively low
-------
plasticizer content in the exposed sheeting
or a loss of plasticizer during exposure.
Physical properties of the CSPE samples
all appeared to be approximately the same.
Recovered samples were substantially
thicker than were the original materials,
partially because of swelling and probably
as a result of the relaxing of the compound
and the puckering of the liner material
(which occurred because of the residual
nerve in the sheeting). The values all
appear to be relatively normal for the CSPE
material. No significant differences were
noted in the data among the different
samples, indicating that sample location in
the cell did not affect results and that the
materials all came from the same lot
The sample of LDPE film was clear after
the surface stain was washed off, and it
appeared to be unaffected by its 9 years of
exposure to the unattenuated leachate.
The sample showed little swelling and its
properties were normal for a 6- to 7-mil
LDPE. No puncture or tears of the material
were observed during samle removal.
TC-2D
From TC-2D, six samples were.taken of
a 30-mil, unreinforced, chlorinated poly-
ethylene (CPE) liner. Four of the samples
were taken from the bottom of the cell, and
two were collected above ground at the
top of the cell (and had thus been exposed
to the weather). Figure 2 shows the
position of the CPE liner in relation to the
other construction details of TC-2D.
The four leachate-exposed CPE samples
from the bottom of TC-2 D had been ex-
posed to all the unattenuated leachate
generated within the cell during the 9
years of operation. Chemical analyses of
the layers of sand above and below the
CPE liner indicated that it has contained
the leachate within the cell. Samples were
stiff and leathery. Though they showed
significant absorption of leachate, their
properties were relatively good. Volatile
contents ranged from 16.7 to 18.8 per-
cent The latter value is equal to an
increase of 23 percent by weight (based
on the original), or a 31.7-percent increase
by volume.
The two weather-exposed samples of
CPE line that had been collected above the
ground where the liner extended beyond
the cell had not been exposed to any
leachate. These samples were significantly
higher in tensile strength, moduli, and
puncture resistance compared with the
leachate exposed samples. The lower
values for the latter probably reflect the
swelling by leachate, but crosslinking
during exposure may contribute to the
higher values of the weathered samples.
r 1R" f f S N- ^ ^f?" '—
Y/SSS6 mil. LDPE liner //;
f SS / S v t mi- t-isi k in id
m//////////,
?5S
Figure 1. Cross section of TC-1 at Observation Bulkhead.
M
Refuse Fill
^ Medium sand
— Gravel
— 30-mil CPE liner
Medium sand
1 Natural clay
Figure 2. Test cell construction details for TC-2D.
-------
An investigation of the subsoils in TC-
2D revealed that the CPE liner was under
an upward hydrostatic pressure from fluids
in the underlying sand. Analyses showed,
however, that the fluid did not contain
leachate The sand immediately below the
CPE liner was a light tan except for a 1.3-
to 1.9-cm ('/2 to %-in.) gray zone at the
point of contact with the liner. The thick,
natural clay section below the sand was a
mottled gray-green in the upper2.5 to5.1
cm (1 to 2 in.). The remainder was a
natural orange-tan.
Conclusions
All liners provided effective containment
of leachate, even after considerable length
of service and exposure. Though the
polymeric liners experienced swelling and
absorption of leachate, their physical
properties remained relatively unaffected
Weathering of polymers caused stiffening
and loss of plasticizer, suggesting that a
protective soil cover is important for such
liners. The clay liner experienced some
leakage, but this problem was apparently
the result of accidental puncture during
test cell construction.
Investigations like this one are vital to
determining whether or not liners are
preventing damage to the environment
Most liners are installed with the assump-
tion that they will function as protective
barriers indefinitely. Such is not always
the case, however, and actual sampling of
such liners would establish their integrity,
especially after the liner has been in contact
with the leachate for some time.
Detecting liner failure and its causes is
hampered greatly by the lack of records
and data on site preparation, liner installa-
tion procedures, protection of completed
liners, and landfill operations. Availability
of such data is critical to predicting the
containment capabilities of waste disposal
sites.
Recommendations
1. Standards for testing liner materials
should be established to determine
longevity under various conditions and
to guide the selection of liner materials.
2. Regulatory agencies should be en-
couraged to prepare guidance doc-
uments incorporating minimum design
and construction standards and speci-
fications for liner installation at various
types of disposal facilities.
3. Surveillance, inspection, or certifica-
tion procedures should be introduced
to attest to correct liner selection and
installation.
4. A more extensive liner testing and
sampling data bank should be developed
to ensure that the information is avail-
able both to regulatory agencies and
to site designers, owners, and operators.
5. Site owners should be provided with
assurances of anonymity and protec-
tion from certain legal liabilities in
return for participation in investiga-
tions of this nature. Such assurances
might require that financial support be
given to site owners to correct pro-
blems discovered during sampling.
The cost of insurance protection should
be incorporated directly as a project
cost
The full report was submitted in fulfill-
ment of Contract No. 68-03-2824 by
EMCON Associates under the sponsorship
of the U.S. Environmental Protection
Agency.
This Project Summary was prepared by staff of EMCON Associates, San Jose, CA
95112.
Robert Landreth is the EPA Project Officer (see below).
The complete report, entitled "Field Verification of Liners from Sanitary Landfills,"
(Order No. PB 83-217810; Cost: $8. SO, subject to change} will be available only
from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
•&U. S. GOVERNMENT PRINTING OFFICE: 1983/659-095/0722
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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