TD367
.R37
1982y
OOOD82002
DRAFT
RCRA GUIDANCE DOCUMENT
WASTE PILE DESIGN
LINER SYSTEMS
[To be used with RCRA Regulations
Sections 264.251U), 264.252 and 264.2533
ISSUED: ?/ /82
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U,S.
••••••->•-,
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TABLE OF CONTENTS
A. Purpose and Use
B. Liner System Function, Components, and Life
1. The Regulations
2. Guidance
3. Discussion
C. Leachate Detection, Collection, and Removal Systems
1. The Regulations
2. Guidance
3* Discussion
D. Liner Specifications
1. The Regulations
2. Guidance
3. Discussion
E. Waste Piles Eligible for Exemption from Subpart F
1. The Regulation
2. Guidance
3* Discussion
Appendices
A. Hydraulic Conductivity Test Method
B. Compatibility Test Method
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A. Purpose and Use
This guidance document is intended to supplement the
regulations in Part 264, Subpart L, applicable to owners and
operators of facilities that use waste piles to store or treat
hazardous wastes.1/ The design requirements in Subpart L
are expressed in terms of the performance to-be achieved by
a pile's design rather than specific design standards
such as type and thickness of liner material. Because of the
non-specific nature of the regulations, the Agency is using
this guidance to assist both permit applicants and permit
writers in determining what constitutes an acceptable lineyr
system design. It contains liner design specifications- which
the Agency considers as. meeting the design requirements of
§264.25Ka).
The designs included in guidance at this time are by no
means intended to cover the entire spectrum of acceptable •
liner systems. Indeed, all of the designs included are
intended only for use in the unsaturated zone (i.e., above '
the high water table). This does not mean that the Agency
has ruled out the location of facilities in the saturated
zone. However, permit applicants seeking to locate in the
I/ Prior to reading this guidance document, the reader should
familiarize himself with the regulations in Subpart L -
of Part 264 and the associated preamble discussions.
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saturated zone cannot necessarily rely on the designs
specified irf this guidance but rather must demonstrate that
their intended design meets the standards of §264.251(a),
in their specific location.
The Agency Intends to supplement this guidance with
additional designs in the future. It is expected that
these additional designs will address location in the saturated
zone. However, the Agency anticipates that most waste piles
will be located on and above the land surface and hence the
need for specifying designs suitable for placement in the
saturated zone is less compelling for waste piles than for
other types of disposal units.
The basic performance goal for waste pile liner designs
is that they prevent the release of hazardous constituents
to ground and surface waters through closure. Subpart L
covers only waste piles from which all wastes, waste residues,
containment system components (e.g., liners), and contaminated
subsoils will be removed at closure. Waste piles from which
wastes, waste residues, contaminated containment system
components, and contaminated subsoils will not be removed at
closure are regulated as landfills under Subpart N.
As promulgated on January 12, 1981, Subpart L included
two acceptable waste pile designs, both of which were Intended
to provide complete containment. In essence, these designs
were either an essentially impermeable base of sufficient
strength to allow for the periodic removal of all wastes from
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the pile in order to physically inspect the base or a double
liner with a leachate detection, collection, and removal
system. Both of these designs are included in this guidance
with further elaboration on specifics such as liner material
and liner thickness.
In accordance with the revised Subpart L, however,
waste piles are not limited to employing one of these two
designs. Therefore, this guidance also prescribes designs-
which include either a single soil liner or a single synthetic
liner.
This document is arranged according to the section of
the regulation to which it corresponds. Those wishing to
send technical information or suggestions concerning this
document should address them to: Rod Jenkins, Chief, Land
Disposal Branch, Office of Solid Waste, WH-565E, U.S.
Environmental Protection Agency, 401 M Street, S.W., Washington,
B.C., 20460. EPA is particularly interested in information
and suggestions concerning the usefulness of the document,
expansion of it, and the effectiveness of the guidance
contained in ensuring compliance with the performance
requirements in the regulations.
EPA is also producing a series of Technical Resource
Documents (TRDs), two of which cover caps and liners. The
TRDs are designed to comprehensively but concisely present the
sum total of the body of information and experience gained by
the Agency over the years on a given topic. As such, they
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contain factual summaries concerning the experiences and
effectiveness of design alternatives, covering what has been
found not to work, as well as what has been found to be
effective. They contain no policy-related direction. The
TRDs can be considered as technical background or development
documents supporting these guidance documents and the
regulations. Based on the information contained in the TRDs,
the Agency made the policy decisions which resulted in the
regulations and these guidance documents. One TRD that
corresponds to guidance in this document is Lining of Waste
Impoundment and Disposal Facilities (SW-870) NTIS Publication
No. PB-81-166-365. It can be obtained from the National
Technical Information Service, U.S. Department of Commerce,
Springfield, VA 22161. The Agency plans to publish an amended
version of this document in the Pall of 1982.
B. Liner System Function, Components, and Life
1. The Regulations
In accordance with §264.251(a), a waste pile liner system
must be designed, constructed, and maintained to prevent, through
scheduled closure, the migration of hazardous constituents
from the pile to the surrounding environment. The liner may be
constructed of materials that may allow waste or hazardous
constituents to migrate into the liner, but must not allow
migration through the liner into the adjacent subsurface soil
or ground or surface water during the active life of the pile.
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All waste piles must be designed, constructed, and operated
with a leachate detection, collection, and removal system
above the primary liner. Waste piles must be designed and
operated to maintain less than a 30 centimeter (1 foot)
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leachate depth over the bottom of the pile.
2. Guidance
(a) Liner systems should be constructed wholly above
the seasonal high water table, i.e., in the unsaturated soil
or above grade (i.e., on the surface);
(b) As a minimum, the liner system should consist of a
single liner of soil (clay), synthetic material, or admixed
material;
(c) Where a synthetic liner is used under any pile
which will not complete closure for 30 or more years after
first placement of wastes, the underliner system should
consist of the following as a minimum:
(i) a primary synthetic liner; and
(ii) a secondary soil (clay) liner.
(d) All waste piles must have a leachate detection,
collection, and removal system installed above the primary liner.
3. Discussion
In developing the designs contained in this guidance,
the Agency has attempted to come as close as possible to
complete containment for the life of the waste piles. However,
the Agency also considered, as an overriding criterion, that
the designs included in this guidance be based on conventional
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technology, utilizing readily available equipment and materials,
at practical costs.
Essentially complete but temporal containment is
practical using newly developed synthetic liners now on the
market. However, experience with synthetic liners in contact
with chemicals is relatively recent, hence EPA has no experience
base from which to predict the life of these materials.
However, predictions based on chemistry and limited recent
real world experience are sufficient to convince the Agency
that with proper selection for resistance to wastes and
leachate at the site and proper installation (tight seams and
no tears), containment for at least 30 years is practical
using a single synthetic liner. Therefore, a single synthetic
liner is described for waste piles which will complete closure
in less than 30 years.
Soil liners, in contrast to synthetic liners, will
become saturated with leachate and will eventually release
hazardous constituents. However, predictions can be made on
the flow time of leachate through soil liners. Therefore,
if the soil used possesses appropriate properties, is properly
placed, and is of sufficient thickness, soil liners can be
expected to provide containment for the life of the waste
pile. Thus, because Subpart L requires the removal of all
wastes and liners (including saturated clays), and any con-
taminated subsoils at closure, no hazardous constituents
should be released to ground-water, even if through damage,
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a small breach occurs in the liner system.
A third option for waste piles is a single base of
admixed materials such as concrete or asphalt. Such bases
must be thick enough to be structurally stable in the specific
location. A structurally stable base is one which is not
prone to cracking or crumbling under the conditions to which
it will be exposed. Appropriate base materials should be
chosen in consideration of the specific waste anticipated
to be stored or treated in the pile.
For waste piles which will not close within 30 years and
which incorporate a synthetic membrane, the Agency suggests a
double liner system Incorporating a top synthetic liner and
a secondary soil (clay) liner. With the double liner system,
if the primary synthetic liner deteriorates in the future,
the secondary soil (clay) liner will minimize transmission of
leachate henceforward. Natural materials such as clay are
not prone to deterioration overtime and should function
essentially forever unless physically damaged or affected by
chemical constituents. Liners of admixed materials such
as concrete or asphalt may also be used for long lived waste
piles when an analysis of the chemistry and physics of the
application indicates that the liner will not deteriorate
and lose function during the pile life.
C. Leachate Detection, Collection, and Removal Systems
1. The Regulation
The regulations require waste piles to be designed and
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constructed with a leachate detection, collection, and removal
system. In addition, waste piles must be designed and operated
to maintain less than a 30 centimeter (1 foot) leachate
depth over the bottom of the pile.
Leachate detection, collection, and removal systems must
be constructed of materials that are chemically resistant to
the waste managed and leachate generated in the pile and of
sufficient strength and thickness to resist collapse and clogging
under the pressures exerted by overlying waste, cover material,
and equipment used at the pile.
2. Guidance
Leachate detection, collection, and removal systems
should have:
(a) At least a 30 centimeter (12 inch) drainage layer
with a-hydraulic conductivity not less than 1 x 10~3 cm/sec
and a minimum slope of 2 percent; and
(b) A graded granular or synthetic fabric filter above
the drainage layer to prevent clogging, except in the case of
leachate detection, collection, and removal systems in direct
contact with the primary synthetic liner. If a granular
filter is used, the grain size should meet the following
criteria:
D15 (filter soil) < 5
D85 (drainage layer) ~
and
D15 (filter soil) = 5-20
D15 (drainage layer)
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and
D50 (filter soil) < 25
D50 (drainage layer) ~"
where:
D15 * grain size, in millimeters, at which 15/5 of the
filter soil used, by weight, is finer:
D85 * grain size, in millimeters, at which 8555 of the
drainage layer media, by weight, is finer;
D50 = grain size, in millimeters, at which 50/5 of the
filter soil or drainage media, by weight, is
finer; and
(c) A drainage tile system of appropriate size and
spacing and a sump pump or other means to efficiently remove
leachate.
(d) Where the waste is sufficiently porous that a one
or more foot head will not develop within the pile, the
owner or operator need only collect and manage the leachate
that runs out from under the pile.
3. Discussion
The Agency believes that it is practical to design a
leachate detection, collection, and removal system to maintain
leachate depth at one foot or less, except perhaps temporarily
during severe storms. The specifications presented here,
judiciously applied, are expected to accomplish that requirement
The minimum thickness (30 centimeters or 12 inches) of
the drainage layer is designed to allow sufficient head to
promote drainage. The two percent minimum slope is also
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designed to promote drainage. In most cases, the Agency
believes thicker drainage layers and greater slopes will
be selected by owners and operators to maximize the efficiency
of the leachate detection, collection, and removal system.
The hydraulic conductivity of not less than 1 X 10~3 cm/sec
was chosen because materials widely used as drainage media
are typically at least that coarse. Additionally, where a
soil or admixed liner is used under the leachate detection,
collection, and removal system, the specification provides
four orders of magnitude difference between the drainage
layer and the soil (clay) or admixed liner (which should
have a hydraulic conductivity of not more than 1 X 10-7
cm/sec). Data available to the Agency show a significant
increase in the efficiency of drainage when a four order of
magnitude difference exists.
Drainage tile diameter and spacing are important because
they affect the head which builds up on the bottom liner between
the tiles. The closer the tiles are together, the less the
head. Also, the tile diameter should be large enough to
efficiently carry off the collected leachate. Since the
philosophy for all aspects of liner design is to minimize
liquid transmission through the liner system, the head on
the liner should be minimized. But the spacing and size of
the tile system necessary to accomplish this depends on
other characteristics of the drainage layer (e.g., media
hydraulic conductivity) and on the impingement rate of liquids
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which is a function of precipitation. The Agency is therefore
not specifying minimum tile spacing or size in this guidance.
However, EPA believes that a design incorporating 4 in.
diameter tiles on 50 to 200 foot (15 to 60 meter) centers
will effectively minimize head on the liner systems. The
owner or operator should demonstrate through appropriate
design calculations in his application that the one foot head
requirement is being or will be achieved.
The leachate detection, collection, and removal system
should also be overlain by a graded granular or synthetic fabric
filter. The purpose of this is to prevent clogging of the pores
in the drainage layer of the collection system by infiltration
of fines from the waste. If a granular filter is used, it is
important that the relationship of grain sizes of the filter
medium and the drainage layer be appropriate if the filter is
to fulfill its function to prevent clogging of the drainage
layer and not contribute to clogging. The guidance specifies
a criterion for this purpose which is widely used in construction
to prevent clogging (binding) of drainage media. The criterion
was developed by the U.S. Army Corps of Engineers and is used
in their engineering manuals.
The waste in many piles will be highly porous. In these
cases, a one foot head will not develop because the percolating
leachate will simply move laterally to the edge of the pile
without mounding significantly. In this case, no special
collection pipes or other structures may be necessary. Where
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such piles are located at OP above grade, the run-off control
system required by the regulations plus the liner itself may
function as the required leachate detection, collection, and
removal system. Small piles of coarse materials on admixed
bases with curbs and sloped drain will often comply in this way.
D. Liner Specifications
1. The Regulations
As discussed in Section B of this guidance, waste pile
liners must be designed and constructed to prevent release
of hazardous constituents to surrounding soils during the
life of the pile. To accomplish this, liners or bases must
be constructed of materials which have appropriate chemical
properties and strength, and which are sufficiently thick to
prevent failure due to physical contact with the waste and
leachat-e present at the facility and climatic conditions in
the area. Liners must also be able to withstand the stress
of installation and daily operation and be resistant to
failure due to pressure gradients, including static head and
external hydrogeologic forces. To provide additional protection
againat failure due to pressure gradients above and below
the liner system, liners must be placed on a foundation or
base capable of providing support.
2. Guidance
Section B of this guidance identifies those liner systems
the Agency believes are appropriate for waste piles, based on
length of service of the waste pile. This section provides
/Z.
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further detail on the acceptable specifications for such
liner systems.
~ (a) Synthetic liners should:
(1) Consist of at least a 30 mil membrane that is
chemically resistant to the waste managed and the leachate
generated at the waste pile. In Judging chemical compatibility
of wastes and membranes, the Agency will consider appropriate
historical data, demonstrations involving theorectical chemistry
and actual test data. Testing of chemical resistance of
liners should be performed using either the EPA test method
attached or an equivalent test method.
(11) Be protected from damage from above and below the
membrane by at least 15 centimeters (6 Inches) of bedding
material no coarser than Unified Soil Classification System
(USCS), sand (SP) and which is free of rock, fractured stone,
debris, cobbles, rubbish, roots, and sudden changes in grade.
Leachate detection,, collection, and removal systems, soil
(clay) liners,, or natural in situ soils may serve as bedding
materials when in direct.contact with synthetic liners if they
meet the requirements specified herein.
(b) Soil liners should:
(1) Consist of at least 60 centimeters (24 inches) of
natural or recompacted eraplaced soil (e.g., clay) with a
saturated hydraulic conductivity not more than 1 x 10~?
cm/sec. Saturated hydraulic conductivity testing should be
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equivalent.
(11) Have a saturated hydraulic conductivity which is
not increased beyond 1 x 10-7 cm/sec as a result of contact
with the waste and leachate generated at the waste pile.
Testing of the effect of leachate on soil liner hydraulic
conductivity should be performed using either the EPA test
method attached or an equivalent test method.
(iii) Have no lenses, cracks, channels, root holes, or
other structural imperfections that can increase the nominal
hydraulic conductivity of the liner above 1 x lO"? cm/sec, and
(iv) Where recompacted emplaced soil liners are used,
be placed in lifts not exceeding 15 centimeters (6 inches)
before compaction to maximize the effectiveness of compaction.
(c) Single soil liners (i.e., those not used in
conjunction with a synthetic liner) should:
(i) Have a sufficient thickness of natural or recompacted
emplaced soil to contain the waste (i.e., no fluid flow moves
beyond the liner) during the facility's operating life; the
necessary thickness being determined by using the following
formula:
where :
d = necessary thickness of soil (feet)
Q m total porosity
k * hydraulic conductivity (ft/yr)
h » maximum fluid head on the base (feet)
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h = maximum fluid head on the base (feet)
t = pile life from start-up through closure (years);
(ii) Have a hydraulic conductivity which is not increased
beyond that used in the calculation as a result of contact
with the waste managed and leachate generated at the pile.
Testing of the effect of leachate on soil liner hydraulic
conductivity should be performed using either the EPA test
method attached or an equivalent test method. A copy of the
relevant method is included in the Appendix to this document.
(ill) Have no lenses, cracks, channels, root holes, or
other structural imperfections that can increase the nominal
hydraulic conductivity above that used in the calculation of
liner thickness; and
i
(iv) Where recompacted emplaced soil liners are used,
be placed in lifts not exceeding 15 centimeters (6 inches)
before compaction to maximize the effectiveness of compaction.
(d) Bases of admixed'materials (e.g., concrete or
asphalt) should be:
(i) Of a thickness that the owner or operator can
demonstrate is structurally stable (i.e., not prone to cracking
or crumbling) when used in the location and with the wastes
managed at the pile;
(ii) Of a sufficient thickness and of appropriate
material to contain the waste (i.e., no fluid moves beyond
the liner) during the pile's operating life;
(iii) Of a sufficient strength and thickness to support
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mechanical equipment used to place or remove wastes.
3. Discussion
i. Synthetic Liners
EPA believes synthetic liners should be at least 30 mils
thick. Thinner synthetic membrane liners are reported to
be readily damaged. One of the primary reasons for failure of
synthetic liners is damage such as punctures, rips, and tears
occurring during installation or operation. To help guard
against this kind of damage, it is good practice to protect
synthetic liners by a minimum of six inches of bedding material.
This will protect against punctures, tears, and rips due to
contact with sharp objects or other conditions. The potential
for puncture is a more prevalent problem for waste piles and
landfills than it is for surface impoundments because of
the waste types and the nature of the waste placement activities,
The wastes themselves may be capable of causing damage because
they contain sharp objects or abrasives. The act of placing
wastes sometimes causes damage, (e.g., due to dropping of
wastes, or driving of vehicles on the liner). The top bedding
layer also protects the synthetic membrane from damage due
to exposure to sunlight and wind while it is exposed. The
bedding layer should consist of materials which are no coarser
than sand (SP) as defined by the Uniform Soil Classfication
System (USCS). Use of a sand layer is common practice for
protection of membranes and other delicate materials from
damage due to contact with grading equipment and materials,
sharp materials in the soil, etc. The bedding material need
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not be-a separate layer as natural soils or the leachate
detection, collection, and removal system materials will
often meet the necessary criteria.
The Agency had intended to incorporate the National Sanita-
tion Foundation's (NSP) standard specifications for flexible
membrane liners as part of this guidance. This would have
provided minimum recommendations with regard to physical
properties, construction practices, seaming tests, etc. An
NSP committee has been studying the subject for some time, and
EPA believes that the specifications which are being developed
are reasonable and well thought out. However, at this point,
the NSP has not formally adopted the draft standards. Therefore,
given the possibility that they might still be changed, EPA
believes it prudent to wait for formal adoption by the NSP before
incorporating them into this guidance document. The NSP speci-
fications are not intended to comprehensively cover the
myriad of hazardous waste applications, however. Therefore,
the Agency believes that some augmentation of the NSF specifica-
tions is appropriate. A few additions have been made (e.g.,
the 30 mil thickness requirement) and more may be incorporated
if experience warrants.
ii. Soil Liners
Soil liners will normally consist of in situ or emplaced
clay soils. Soils should have a saturated hydraulic conductivity
of not more than 1 x 10-7 cm/sec and be at least 60 centimeters
(2 feet) thick. To minimize the transmission of leachate,
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the soil liner should be as tight as practical. Many clays
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can readily be recompacted to meet the specified level. It
is not clear, however, that recompacting to meet a tighter
specification can be routinely accomplished. In concert
with the philosophy of these designs, soil liners are meant to
minimize the movement of liquid flow through them, so that
leachate does not traverse all the way through the liner
before closure when the liner is removed. Both tightness and
thickness of the soil are important in this regard. However,
in any event, a minimum thickness is necessary to retain
structural stability (reduce cracking potential, etc). Two
feet is generally accepted to be a minimum stable thickness
for recompacted clay.
Another function of liners is to improve the efficiency
of the leachate detection, collection, and removal system.
i
Synthetic membranes typically achieve virtual complete
rejection of fluids and are thus most effective. Soil (clay)
liners do allow a small portion of the liquid reaching them
to enter the pore structure and ultimately escape. The
tighter the clay layer, the less fluid will seep into it, and
therefore, the more fluid will be removed by the detection,
collection, and removal system. Prom a fluid rejection
efficiency point of view, the thickness of the soil layer is
not crucial except Insofar as it affects structural stability.
Tightness is the most important characteristic.
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When discussing the relative tightness of soils, the
term permeability is most often used. This is a generic
term, referring to the property in general. In this guidance,
EPA uses the more specific term —"hydraulic conductivity".
An acceptable test method for soil hydraulic conductivity
has been included in the Appendix to this document.
In situ soil can be considered acceptable as soil liner
material provided the specifications in this guidance are
met. Natural soil liners should be free of conduits and
channels which would convey liquids through the liner. This
includes root holes, sand lenses, cracks, fractures, etc.
iii. Admixed Material Liners
The term "admixed liner" covers a multitude of materials
with widely varying physical and chemical properties. Some
are soil like, others are rigid, and some may contain synthetic
materials. Among the most commonly used admixed materials
used under piles are asphalt and concrete. Both are typically
fashioned into rigid pads on which the pile is deposited.
Addition to and removal from the pile is usually by front end
loader and the rigid nature of this base is ideal for such
operations.
Prom a containment standpoint, the important features of
an admixed liner are much the same as for soil liners; i.e.,
the permeability and thickness of the liner or pad must be
such that the leachate will not pass through the liner prior
to closure when the pad is removed. Proper function in this
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and liner materials but recognizes that historic data (e.g. results
elsewhere with similar wastes) or theorectical chemistry may
provide sufficient information in some cases. Data currently
available to EPA indicate that the following combinations of
waste types and liner materials are often incompatible:
(a) Chlorinated solvents tend to dissolve polyvlnyl.
chloride (PVC).
(b) Chlorosulfonated polyethylene can be dissolved by
aromatic hydrocarbons.
(c) Clays may exhibit high permeability when exposed to
concentrated organics,, especially organics of high and low pH.
(d) Asphaltic materials may dissolve in oily wastes.
(e) Concrete and lime based materials are dissolved by.
acids.
The Agency is currently developing a more comprehensive
summary of .waste/liner compatibility information which will
be included in a later edition of this document.
An acceptable test method for evaluating waste/liner
compatibility is included in the Appendix to this document.
The test method exposes a liner sample to the waste or leachate
encountered at the pile. After exposure, the liner sample
is tested for important characteristics—saturated hydraulic
conductivity in the case of soil liners; strength (tensile,
tear, and puncture), weight loss, and hydraulic conductivity
in the case of synthetics. The Agency considers any significant
deterioration in any of the measured properties to be evidence
of incompatibility unless a convincing demonstration can be
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made that the deterioration exhibited will not impair the
integrity of the liner over the life of the pile. Even
though the tests may show the amount of deterioration to be
relatively small, the Agency is concerned about the cumulative
effects of exposure over very much longer periods than those
actually tested.
Once the NSF strength specifications previously discussed
have been published, EPA plans to incorporate them in
conjunction with the compatibility method for synthetic liners -
attached, in an improved method of evaluating liner compatibility,
While the Agency does not want to prejudge how this may be
done, one possible approach might be to extrapolate the
strength curves developed by the test method to the expected
life of the facility. The expected strength at- that time
could then be compared against minimal acceptable strength
levels, e.g. the NSP strength specifications or some acceptable
fraction of them. The Agency is interested in comments,
suggestions, and data on the subject of evaluating strength
loss on exposure to chemical leachates.
E. Waste Piles Eligible for'Exemption from Subpart P
1. The Regulations
Sections 264.252 and 264.253 contain exemptions from
Subpart P (the ground water protection standard and associated
monitoring and remedial action requirements) for certain
waste piles. Eligible waste piles must be located above the
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water table, designed and operated with a leachate detection
collection and removal system and either (1) a double liner
system designed and constructed to prevent discharge during
the life of the waste pile, with a leak detection system
between the liners; or (2) a base, designed and operated to
prevent discharge during the life of the pile, underlying
and in contact with the pile, which is of sufficient strength
and thickness to allow waste to be removed from the pile to
expose the liner surface for inspection without causing
damage to the base.
2. Guidance
(a) Owners and operators of waste piles designed as
follows are eligible for an exemption from Part 264, Subpart P
in accordance with §264.252:
(1) Waste piles which are designed with an under-
liner system consisting of the following, as a minimum and
located wholly within the unsaturated zone (i.e., above, the
seasonal high water table) should have:
(i) A primary liner, and
(ii) A leachate detection, collection, and removal system
meeting the specifications contained in §C(2) of this guidance,
and
(iii) A secondary synthetic liner meeting the specifications
contained in §D (2)(a) of this guidance, and
(v) A leak detection system between the liners, and
(vi) For waste piles which will not complete closure for
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30 or more years In accordance with the closure plan
required by §264.112, a tertiary soil liner meeting the
specifications contained in §D(2)(b).
(b) Owners and operators of waste piles designed as
follows are eligible for an exemption from Part 264, Subpart
P in accordance with §264.253:
(1) Waste piles which are designed with a underllner system
consisting of the following, as a minimum and located wholly within
the unsaturated zone (i.e., above the seasonal high water
table) should have:
(i) A base of admixed materials meeting the specifications
contained in §D (2)(d) of this guidance, and
(ii) A leachate detection, collection, and removal
system.
3. Discussion
Sections 264.252 and 264.253 of Subpart L contain
descriptions of two types of waste piles eligible for an
exemption from Subpart P of Part 264. Because that description
is essentially performance oriented with only a general
description of specific eligible designs, this guidance
offers more specificity as to what the Agency considers
adequate to meet the performance requirements.
As stated in the preamble to Subpart L, the Agency generally
does not consider waste piles designed with single soil liners or
bases to be appropriate for an exemption from Subpart P.
Likewise, waste piles with a single synthetic liner are not
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eligible for an exemption from Subpart P.
The monitoring program incorporated in Subpart P serves
as a backup to the design and operating performance requirements
of this section by detecting unexpected ground-water contamination
from the pile. Before the provisions for Subpart P can be
safely waived, an alternate monitoring system must be in
place to identify breaches in the containment system before
ground-water contamination can occur. The Agency has identified
two appropriate designs in the regulations which provide early
warning monitoring of the containment system. Double lined
waste piles with leachate detection, collection, and removal
systems will be able to detect a breach in the primary liner
if leachate is detected between the liners by the leak detection
system. Waste piles with single bases of admixed materials
can detect breaches by removal of wastes and physical inspection
of the base.
Double lined waste piles will usually have synthetic
liners. If they will operate for more than 30 years the
bottom synthetic liner should be underlain by a clay liner
Since waste piles are storage facilities, owner or operator
may chose to use only soil or admixed liners, properly designed
to retard movement through them during the life of the unit,
for one or both liners. However, since leakage of any fluid
into the leak detection system will be considered evidence
that one of the liners has failed and since the consequences
of liner failure are substantial, EPA expects most owners or
-------
operators to chose the more impermeable synthetics when
designing double lined facilities.
The leak detection system between the liners can conceivably
be constructed in a variety of ways including the use of
advanced instrumentation. A relatively simple leak detection
system, depending on gravity flow, is very similar to a leachate
detection, collection, and removal system and can be acceptably
constructed in accordance with the guidance in Section C of
this document.
Single bases from which wastes can be removed for the
purpose of physical inspection of the base will generally be
constructed of concrete or asphalt and should meet the
specifications of Section D. In designing and constructing
the pad or base, the owner or operator should carefully
consider the ability of the base to withstand chemical attack
by leachates and to bear the load and withstand the other
forces associated with placing and removing the waste because
if deterioration of the base is in evidence during routine
Inspections, he must either repair the base or lose his
exemption from Subpart P.
Single base waste piles must be designed and constructed
with a leachate detection, collection and removal system.
However, in many cases, the leachate detection, collection,
and removal system described in Section C of this guidance
may not be appropriate for such piles since such piles must
be periodically cleared to allow for inspection of the base.
-------
APPENDIX A
METHODS FOR DETERMINING SATURATED
HYDRAULIC CONDUCTIVITY, SATURATED
LEACHATE CONDUCTIVITY, AND
INTRINSIC PERMEABILITY
-------
For single base waste piles constructed of admixed materials,
the run-off control system in combination with the liner itself,
may be sufficient for the purpose of leachate collection and
removal.
2.7
-------
TABLE OF CONTENTS
Page
1.0 INTRODUCTION 1-1
1.1 SCOPE AND APPLICATION 1-1
1.2 DEFINITIONS 1-5
1.2.1 Units 1-5
1.2.2 Fluid potential or head 1-6
1.2.3 Hydraulic potential or head 1-6
1.2.4 Hydraulic conductivity 1-6
1.2.5 Fluid conductivity 1-7
1.2.6 Leachate conductivity 1-8
1.2.7 Aquifer 1-8
1.2.8 Confining layer 1-8
1.2.9 Transraissivity 1-8
1.3 TEMPERATURE AND VISCOSITY CORRECTIONS 1-9
1.4 INTRINSIC PERMEABILITY 1-10
1.5 RANGE OF VALIDITY OF DARCY'S LAW 1-10
1.6 METHOD CLASSIFICATION 1-12
2.0 LABORATORY METHODS 2-1
2.1 SAMPLE COLLECTION FOR LABORATORY METHODS . . . 2-1
2.2 CONSTANT-HEAD METHODS 2-1
2.3 FALLING-HEAD METHODS 2-3
2.4 GENERAL TEST CONSIDERATIONS 2-5
2.4.1 Fluid Supplies to be Used 2-5
2.4.2 Pressure and Fluid Potential Measurement 2-6
2.5 CONSTANT-HEAD TEST WITH CONVENTIONAL
PERMEAMETER 2-6
2.5.1 Applicability 2-6
2.5.2 Apparatus 2-7
2.5.3 Sample Preparation 2-7
2.5.4 Test Procedure 2-9
2.5.5 Calculations 2-10
-------
TABLE OF CONTENTS (Continued)
2.6 FALLING-HEAD TEST WITH CONVENTIONAL
PERMEAMETER 2-10
2.6.1 Applicability 2-10
2.6.2 Apparatus 2-10
2.6.3 Sample Preparation 2-11
2.6.4 Test Procedure 2-11
2.6.5 Calculations 2-11
2.7 MODIFIED COMPACTION PERMEAMETER METHOD .... 2-12
2.7.1 Applicability 2-12
2.7.2 Apparatus 2-12
2.7.3 Sample Preparation 2-12
2.7.4 Test Procedure 2-13
2.7.5 Calculations 2-13
2.8 TRIAXIAL-CELL METHOD WITH BACK PRESSURE .... 2-13
2.8.1 Applicability 2-13
2.8.2 Apparatus 2-15
2.8.3 Sample Preparation ........... 2-15
2.8.4 Test Procedure 2-15
2.8.5 Calculations 2-19
2.9 PRESSURE-CHAMBER PERMEAMETER METHOD 2-19
2.9.1 Applicability 2-19
2.9.2 Apparatus 2-19
2.9.3 Sample Preparation 2-19
2.9.4 Test Procedure 2-21
2.9.5 Calculations 2-21
2.10 SOURCES OF ERROR FOR LABORATORY TEST FOR
HYDRAULIC CONDUCTIVITY 2-21
2.11 LEACHATE CONDUCTIVITY USING LABORATORY METHODS 2-23
2.11.1 Applicability 2-23
2.11.2 Leachate Used 2-24
2.11.3 Safety 2-24
2*11.4 Procedures . 2-25
2.11.5 Apparatus 2-25
2.11.6 Measurements 2-25
2.11.7 Calculations ... 2-26
ii
-------
TABLE OF CONTENTS (Continued)
Page
3.0 FIELD METHODS 3-1
3.1 WELL-CONSTRUCTION CONSIDERATIONS 3-2
3.1.1 Well Installation Methods 3-2
3.1.2 Wells Requiring Well Screens 3-3
3.1.3 Wells Not Requiring Well Screens .... 3-5
3.2 WELL DEVELOPMENT 3-5
3.3 DATA INTERPRETATION AND TEST SELECTION
CONSIDERATIONS 3-6
3.4 SINGLE WELL TESTS 3-8
3.4.1 Method for Moderately Permeable . -
Formations Under Confined Conditions . . 3-8
3.4.2 Methods for Extremely Tight Formations
Under Confined Conditions 3-13
3.4.3 Methods for Moderately Permeable
Materials Under Unconfined
Conditions 3-17
3.5 MULTIPLE WELL TESTS 3-22
3.6 ESTIMATES OF HYDRAULIC CONDUCTIVITY FOR
COARSE-GRAINED MATERIALS 3-22
3.7 CONSOLIDATION TESTS 3-25
3.8 FRACTURED MEDIA 3-26
4.0 CONCLUSION 4-1
5.0 REFERENCES 5-1
6.0 APPENDIX A 6-1
iii
-------
TABLE OF CONTENTS (Continued)
LIST OF TABLES
Table No. Page
A HYDRAULIC AND LINER CONDUCTIVITY
DETERMINATION REQUIREMENTS FOR SURFACE
IMPOUNDMENTS, WASTE PILES, AND LANDFILL
COMPONENTS, AS CITED IN RCRA GRUIDANCE
DOCUMENTS AND DESCRIBED IN SW-846 .... 1-2
B SUMMARY OF PUBLISHED DATA ON POTENTIAL
ERRORS IN USING DATA FROM LABORATORY
PERMEABILITY TESTS ON SATURATED SOILS . . . 2-22
C HYDRAULIC CONDUCTIVITIES ESTIMATED FROM
GRAIN-SIZE DESCRIPTIONS 3-24
LIST OF FIGURES
Figure No*
1 PRINCIPLE OF THE CONSTANT HEAD METHOD ... 2-3
2 PRINCIPLE OF THE FALLING HEAD METHOD . . . 2-4
3 APPARATUS SETUP FOR THE CONSTANT HEAD
AND FALLING HEAD METHODS 2-8
4 MODIFIED COMPACTION PERMEAMETER 2-14
, 5 SCHEMATIC DIAGRAM OF TYPICAL TRIAXIAL
COMPRESSION APPARATUS FOR
HYDRAULIC CONDUCTIVITY TESTS WITH
BACK PRESSURE 2-15
6 PRESSURE CHAMBER FOR HYDRAULIC
CONDUCTIVITY 2-20
7 GEOMETRY AND VARIABLE DEFINITION FOR
SLUG TESTS IN CONFINED AQUIFERS ...... 3-10
8 SCHEMATIC DIAGRAM FOR PRESSURIZED
SLUG TEST METHOD 3-15
9 VARIABLE DEFINITIONS FOR SLUG TESTS
IN UNCONFINED MATERIALS 3-18
10 CURVES DEFINING COEFFICIENTS A, B, AND C
to L/rw 3-21
iv
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METHOD SW-846
SATURATED HYDRAULIC CONDUCTIVITY,
SATURATED LEACHATE CONDUCTIVITY, AND
INTRINSIC PERMEABILITY
1.0 INTRODUCTION
1.1 SCOPE AND APPLICATION
This section presents methods available to hydrogeologists and
geotechnical engineers for determining the saturated hydraulic
conductivity of earth materials and conductivity of soil liners
to leachate, as outlined by the Part 264 permitting rules for
hazardous-waste disposal facilities. In addition, a general
technique to determine intrinsic permeability is provided. A
cross reference between the applicable parts of the RCRA
Guidance Documents and associated Part 264 Standards and these
test methods is provided by Table A.
Part 264 Subpart F establishes standards for ground-water
quality monitoring and environmental performance. To
demonstrate compliance with these standards, a permit applicant
must have knowledge of certain aspects of the hydrogeology
at the disposal facility, such as hydraulic conductivity, in
order to determine the compliance point and monitoring well
locations and in order to develop remedial action plans when
necessary.
In this report, the laboratory and field methods that are con-
sidered the most appropriate to meeting the requirements of
-------
1-2
TABLE A
HYDRAULIC AND LINER CONDUCTIVITY DETERMINATION
METHODS FOR SURFACE IMPOUNDMENT
WASTE PILE, AND LANDFILL COMPONENTS, AS CITED
IN RCRA GUIDANCE DOCUMENTS AND DESCRIBED IN SW-846
Surface Impoundments
Guidance
Associated Regulation
Corresponding
SW-846
Section
Soil liner hydraulic
conductivity
Guidance section D(2)(b)(1)
and D(2)(c)(1)/Section
264.221(a),(b)
2.0
Soil liner leachate
conductivity
Guidance section D(2) (b)(2)
and D(2) (c) (2)
Leak detection system
Guidance section C(2)(a)/
Section 264.222
2.0
Final cover drain
layer
Final cover low
permeability layer
Guidance section E(2)(d) (I)/
Section 264.228
Guidance section E(2)(e)(2)(A)/
Section 264.228
2.0
2.0
General Hydrogeologic
site investigation
264 subpart F
3.0
RCRA Guidance Document: Surface Impoundments, Liner Systems,
Final Cover, and Freeboard Control. Issued Julyv 1982.
-------
1-3
Waste Piles
Guidance Cite—'
Associated Regulation
Correspond!*
SW-846
Section
Soil liner hydraulic
conductivity
Guidance section D(2)(b)(i)
and D(2) (c) (i)/
Section 264.251(a)(1)
2.0
Soil liner leachate
conductivity
Guidance section D(2)(b)(ii)
and D(2)(c)(ii)
2.11
Leak Detection
System
Guidance section C(2)(a)/
Section 264.252 (a)
2.0
Leachate collection
and renewal system
Guidance section C(2)(a)/
Section 264.251 (a) (2)
2.0
General hydrogeologic
site investigation
264 subpart F
3.0
—'RCRA Guidance Document:
Issued July, 1982•
Waste Pile Design, Liner Systems,
-------
1-4
Landfills
Guidance Cite—'
Associated Regulation
Corresponding
SW-846
Section
Soil liner hydraulic
conductivity
Guidance section D(2)(b)(I)/
Section 264.301(a)(1)
2.0
Soil liner leachate
conductivity
Guidance section D(2)(b)(2)
2.11
Leak detection
system
Guidance section C(2)(a)/
Section 264.302(a)(3)
2.0
Leachate collection and Guidance section C(2)(a)/
removal system Section 264.301(a) (2)
2.0
Final cover drain
layer
Guidance section E(2)(d)(I)/
Section 264.310(a)(b)
2.0
Final cover low
permeability layer
Guidance section E(2)(e)(2)(A)
Section 264.310(a)(b)
2.0
General hydrogeologic 264 subpart F
site investigation
3.0
— RCRA Guidance Document: Landfill Design, Liner Systems and
Final Cover. Issued July, 1982.
-------
1-5
Part 264 are given in sufficient detail to provide an
experienced hydrogeologist or geotechnical engineer with the
methodology required to conduct the tests. Additional labora-
tory and field methods that may be applicable under certain
conditions are included by providing reference to standard
texts and scientific journals.
Included in this report are descriptions of field methods con-
sidered appropriate for estimating saturated hydraulic conduc-
tivity by single well or borehole tests. The determination of
hydraulic conductivity by pumping or injection tests is not
included because the latter are considered appropriate for well
field design purposes but may not be appropriate for economi-
\ - v
cally evaluating hydraulic conductivity for the purposes set
forth in Part 264 Subpart F.
EPA is not including methods for determining unsaturated
hydraulic conductivity at this time because the Part 264 per-
mitting standards do not require such determinations.
1.2 DEFINITIONS
This section provides definitions of terms used in the remainder
of this report. These definitions are taken from U.S. Govern-
ment publications when possible.
1.2.1 Units; This report uses consistent units in all
equations. The symbols used are:
Length = L,
Mass = M, and
Time = T.
-------
1-6
1.2.2 Fluid Potential or head (h) is a measure of the poten-
tial energy required to move fluid from a point in the porous
medium to a reference point. For virtually all situations
expected to be found in disposal sites and in ground-water
systems, h is defined by the following equation:
h - hp + hz (1)
where
h is the total fluid potential, expressed as
a height of fluid above a reference datum, L;
hp is the pressure potential caused by the
weight of fluid above the point in question, L.
hp is defined by hp = P/pg,
where
P is the fluid pressure at the point in question,
ML-J-T-2,
p is the fluid density at the prevailing tempera-
ture, ML~3,
g is the acceleration of gravity, LT~2, and
hz is the height of the point in question above
the reference datum, L.
By knowing hp and hz at two points along a flow path
and by knowing the distance between these points,
the fluid potential gradient can be determined.
1.2.3 Hydraulic potential or head is the fluid potential when
water is the fluid.
1.2.4 Hydraulic conductivity is the fluid conductivity when
water is the fluid. The generic term, fluid conductity, is
discussed below in 1.2.5.
-------
1-7
1.2.5 Fluid conductivity is defined as the volume of fluid at
the prevailing density and dynamic viscosity that will move in
a unit time under a unit fluid potential gradient through a
unit area measured at right angles to the direction of flow.
It is a property of both the fluid and the porous medium as
shown by the following equation:
K • , (2)
u
where
K is the fluid conductivity, LT~1;
k is the intrinsic permeability, a property of
the porous medium alone, L~2;
y is the dynamic viscosity of the fluid at the
prevailing temperature, ML~1 T~l.
The fluid conductivity of a porous material is also defined by
Darcy's law, which states that the fluid flux (q) through a
porous medium is proportional to the first power of the fluid
potential across the unit area:
q - - Kl, (3)
A
where
q » the specific fluid flux, LT~1,
Q is the volumetric fluid flux, L3T~1,
A is the cross-sectional area, L2, and
I is the fluid potential gradient, L°.
-------
1-8
Oarcy's law provides the basis for all methods used to deter-
mine hydraulic conductivity discussed in this report. The
range of validity of Darcy's law is discussed in Section 1.4
(Lohman, 1972).
1.2.6 Leachate conductivity is the fluid conductivity when
leachate is the fluid.
1.2.7 Aquifer is a geologic formation, group of formations, or
part of a formation capable of yielding a significant amount of
ground water to wells or springs (40 CFR 260.10).
1.2.8 Confining layer is a body of impermeable material stra-
tigraphically adjacent to one or more aquifers. In nature,
however, its hydraulic conductivity may range from nearly zero
to some value distinctly lower than that of the aquifer. Its
conductivity relative to that of the aquifer it confines should
be specified or indicated by a suitable modifier, such as
slightly permeable or moderately permeable (Lohman, 1972).
1.2.9 Transmissivity, T [L^, T"^l , is the rate at which water
of the prevailing kinematic viscosity is transmitted through a
unit width of the aquifer under a unit hydraulic gradient.
Although, spoken of as a property of the aquifer, the term also
includes the saturated thickness of the aquifer and the proper-
ties of the fluid. It is equal to an integration of the
hydraulic conductivities across the saturated part of the
aquifer perpendicular to the flow paths (Lohman, 1972).
-------
1-9
1.3 TEMPERATURE AND VISCOSITY CORRECTIONS
By using Equation 2, corrections to conditions different from
those prevailing during the test can be made. Two types of
corrections can commonly be made: a correction for a tem-
perature that varies from the test temperature, and a correc-
tion for fluids other than that used for the test. The tem-
perature correction is defined by:
m Kt Ut Pf , (4)
Wf Pt
where
the subscript f refers to field conditions, and
t refers to test conditions.
Most temperature corrections are necessary because of the
viscosity dependence on temperature. Fluid density variations
caused by temperature changes are usually very small for most
liquids. The temperature correction for water can be signifi-
cant. A temperature decrease from 75°C to 10°C results in a
68 percent reduction in viscosity and hence hydraulic conduc-
tivity. Equation 4 can also be used to determine hydraulic
conductivity if fluids other than water are used. It is
assumed, however, when using Equation 4 that the fluids used
do not alter the intrinsic permeability of the porous medium
during the test. Experimental evidence exists that shows that
this alteration occurs with a wide range of organic solvents
(Anderson and Brown, 1981). Consequently, it is recommended
-------
1-10
that tests be run using fluids, such as leachates, that might
occur at each particular disposal site. Special considerations
for using non-aqueous fluids are given in Section 3.3 of this
report.
1.4 INTRINSIC PERMEABILITY
Rearrangement of Equation 2 results in a definition of intrin-
sic permeability.
- • (5)
pg
Since this is a property of the medium alone, if fluid proper-
ties change, the fluid conductivity must also change to keep
the intrinsic permeability a constant. By using measured fluid
conductivity, and values of viscosity and density for the fluid
at the test temperature, intrinsic permeability can be determined,
1.5 RANGE OF VALIDITY OF DARCY'S LAW
Determination of fluid conductivities using both laboratory and
field methods requires assuming the validity of Darcy's law.
Experimental evidence has shown that deviations from the linear
dependence of fluid flux on potential gradient exist for both
extremely low and extremely high gradients (Hillel, 1971;
Freeze and Cherry, 1979). The low gradient limits are the
result of the existence of threshold gradients required to ini-
tiate flow ( Swartzendruber , 1962). The upper limits to the
validity of Darcy's law can be estimated by the requirements
-------
1-11
that the Reynolds number, Re, in most cases be kept below 10
(Bear, 1972). The Reynolds number is defined by:
pqd
where
Re = ^ , (6)
y
d is some characteristic dimension of the
system, often represented by the median grain
size diameter, DSQ, (Bouwer, 1978), and
q is the fluid flux per unit area, LT"1.
For roost field situations, the Reynolds number is less than
one, and Darcy's law is valid. However, for laboratory tests
it may be possible to exceed the range of validity by the impo-
sition of high potential gradients. A rough check on accep-
table gradients can be made by substituting Darcy's law in
Equation 6 and using an upper limit of 10 for Re:
, (7)
pKDso
where
K is the approximate value of fluid conductivity
determined at gradient I.
A more correct check on the validity of Darcy's law or the
range of gradients used to determine fluid conductivity would
be to measure the conductivity at three different gradients.
If a plot, of fluid flux versus gradient is linear, Darcy's law
can be considered to be valid for the test conditions.
-------
1-12
1.6 METHOD CLASSIFICATION
This report classifies methods to determine fluid conductivity
into two divisions: laboratory and field methods. Ideally,
compliance with the Part 264 disposal facility requirements
should be evaluated by using field methods that test the
materials under in-situ conditions whenever possible. In
general, field methods can usually provide more representative
values than laboratory methods because they test a larger
volume of material, thus integrating the effects of macro-
structure and heterogeneities. However, field methods pre-
c intly available to determine the conductivity of compacted -
fine-grained materials in reasonable times require the tested
interval to be below a water table, to be fairly thick, or to
require excavation of the material to be tested at some point
in the test. The integrity of liners and covers should not be
compromised by the installation of boreholes or piezometers
required for the tests. These restrictions generally result in
the requirement to determine the fluid conductivity of liner
and cover materials in the laboratory. The transfer value of
laboratory data to field conditions can be maximized for liners
and covers because it is possible to reconstruct relatively
accurately the desired field conditions in the laboratory.
However, field conditions that would alter the values deter-
mined in the laboratory need to be addressed in permit applica-
tions. These conditions include those that would increase con-
ductivity by the formation of microcracks and channels by
repeated wetting and drying, and by the penetration of roots.
-------
1-13
Laboratory methods are categorized in Section 2.0 by the
methods used to apply the fluid potential gradient across the
sample. The discussion of the theory, measurement, and com-
putations for tests run under constant and falling-head con-
ditions is followed by a detailed discussion of tests using
specific types of laboratory apparatus and the applicability of
these tests to remolded compacted, fine-grained uncompacted,
and coarse-grained porous media. Section 2.3 provides a
discussion of the special considerations for conducting
laboratory tests using non-aqueous permeants. Section 2.10
gives a discussion of the sources of error and guidance for
establishing the precision of laboratory tests.
Field methods are discussed in Section 3.0 and are limited to
those requiring a single bore hole or piezometer. Methods
requiring multiple bore holes or piezometers and areal methods
are included by reference. Because of the difficulties in
determining fluid conductivity of in-place liner and cap
materials under field conditions without damaging their
integrity, the use of field methods for fine-grained materials
will be generally restricted to naturally occurring materials
that may serve as a barrier to fluid movement. Additional
field methods are referenced that allow determination of
saturated hydraulic conductivity of the unsaturated materials
above the shallowest water table. General methods for frac-
tured media are given in Section 3.8.
-------
1-14
A discussion of the important considerations in well installa-
tion, construction, and development is included as an introduc-
tion to Section 3*0.
-------
2-1
2.0 LABORATORY METHODS
2.1 SAMPLE COLLECTION FOR LABORATORY METHODS
To assure that a reasonable assessment is made of field con-
ditions at a disposal site, a site investigation plan should be
developed to direct sampling and analysis. This plan generally
requires the professional judgment of an experienced hydro-
geologist or geotechnical engineer. General guidance is pro-
vided for plan development in the Guidance Manual for
Preparation of a Part 264 Land Disposal Facility Permit
Application (EPA, in press). The points listed below should
be followed:
o The hydraulic conductivity of a soil liner should be deter-
mined either from samples that are processed to simulate
the actual liner, or from an undisturbed sample of the
complete liner.
To obtain undisturbed samples, the thin-walled tube sampling
method (ASTM Method # D1587-74) or a similar method may be
used. Samples representative of each lift of the liner
should be obtained, and used in the analyses. If actual
undisturbed samples are not used, the soil used in liner
construction must be processed to represent accurately
the liner's initial water content and bulk density. The
method described in Section 2.7.3 or ASTM Method #D698-70
(ASTM, 1978) can be used for this purpose.
o For purposes of the general site investigation, the general
techniques presented in ASTM method #0420-69 (ASTM, 1978)
should be followed. This reference establishes practices
for soil and rock investigation and sampling, and incorporates
various detailed ASTM procedures for investigations, sampling,
and material classification.
2.2 CONSTANT-HEAD METHODS
The constant-head method is the simplest method to determine
hydraulic conductivity of saturated soil samples. The concept
of the constant-head method is schematically illustrated in
-------
2-2
Figure 1. The inflow of fluid is maintained at a constant
head (h) above a datum and outflow (Q) is measured as a func-
tion of time (t). Using Darcy's law, the hydraulic conduc-
tivity can be determined using the following equation after the
outflow rate has become constant:
K - QL/hA, (8)
where
K » hydraulic conductivity,
L - length of sample, L
A » cross-sectional area of sample, L2
Q » outflow rate, L^T*
h » fluid head difference across the sample, L
Constant-head methods should be restricted to tests on media
* *
having high fluid conductivity.
x
2.3 FALLING-HEAD METHODS
A schematic diagram of the apparatus for the falling-head
method is shown in Figure 2. The head of inflow fluid
decreases from h^ to h2 as a function of time (t) in a stand pipe
directly connected to the specimen. The fluid head at the
outflow is maintained constant. The quantity of outflow can be
measured as well as the quantity of inflow. For the setup shown
in Figure 2a, the hydraulic conductivity can be determined
using the following equation:
log,,
At io hi
-------
2-3
OVE RFLOW
WATER SUPPLY
[
AIN ^
r HEAD
t
L
1 — -t
_-t-
•CR
J
* n / * • *
• • • *• • *•••
: •.•!."...
••••. r-'*:
:•'•,?•.••••
— jir
EEN-^
J
t
l
^^
4
r |
^••MMHMBHi
0«AOUAT1D
CYLINDER
Figure 1.—Principle of the constant head method
-------
2-4
STA
X
NOPIM
"SLT
-
• •
• • •
* • *
, *
a."
o
*
•
•*— 0
• . *
( • •
• •
1
\
91
1
\
•«|
LyJ
^1
»»0
1
\
^
\
1
*l
L
OVERFLOW 1
i
i \
-=—i
KO
r
— -as
_z_
V
• • * • •
• * •
• *
.i Di
• • * *
V
S-"3S
to)
(bl
Figure 2.—Principle of the falling head method
using a small (a) and large (b) standpipe.
-------
2-5
where
a = the cross-sectional area of the standpipe, L2
A « the cross-sectional area of the specimen, L2
L = the length of the specimen, L
t = elapsed time from t^ to t2, T.
For the setup shown in Figure 2b, the term a/A in Equation 9 is
replaced by 1.0. Generally, falling-head methods are applicable
to fine-grained soils because the testing time can be accelerated.
2.4 GENERAL TEST CONSIDERATIONS
2.4.1 Fluid Supplies to be Used
For determining hydraulic conductivity and leachate conduc-
tivity, the supplies of permeant fluid used should be de-aired.
Air coming out of solution in the sample can significantly
reduce the measured fluid conductivity. Deairing can be
achieved by boiling the water supply under a vacuum, bubbling
helium gas through the supply, or both.
Significant reductions in hydraulic conductivity can also occur
in the growth and multiplication of microorganisms present in
the sample. If it is desirable to prevent such growth, a bac-
tericide or fungicide, such as 2000 ppm formaldehyde or 1000 ppm
phenol (Olsen and Daniel, 1981), can be added to the fluid supply.
Fluid used for determining hydraulic conductivity in the labora-
tory should never be distilled water. Native ground water from
the aquifer underlying the sampled area or water prepared to
simulate the native ground-water chemistry should be used.
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2-6
2.4.2 Pressure and Fluid Potential Measurement
The equations in this report are all dimensionally correct;
that is, any consistent set of units may be used for length,
mass, and time. Consequently, measurements of pressure and/or
fluid potential using pressure gages and manometers must be
reduced to the consistent units used before applying either
Equation 8 or 9. Pressures or potentials should be measured
to within a few tenths of one percent of the gradient applied
across the sample.
2.5 CONSTANT-HEAD TEST WITH CONVENTIONAL PERMEAMETER
2.5.1 Applicability
This method covers the determination of the hydraulic conduc-
tivity of soils by a constant-head method using a conventional
permeameter. This method is recommended for disturbed coarse-
\
grained soils. If this method is to be used for fine-grained
soils, the testing time may be prohibitively long. This method
was taken from the Engineering and Design, Laboratory Soils
Testing Manual (U.S. Army, 1980). It parallels ASTM Method
D2434-68 (ASTM, 1978). The ASTM method gives extensive
discussion of sample preparation and applicability and should
be reviewed before conducting constant-head tests. Lambe (1951)
provides additional information on sample preparation and
equipment procedures.
-------
2-8
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Figure 3.— Apparatus setup for the constant head (a)
and falling head (b) methods.
-------
2-7
2.5.2 Apparatus
The apparatus is shown schematically in Figure 3. It consists
of the following:
a. A permeameter cylinder having a diameter at least
8 times the diameter of the largest particle of the
material to be tested,
b. Constant-head filter tank,
c. Perforated metal disks and circular wire to support
the sample,
d. Filter materials such as Ottawa sand, coarse sand, and
gravel of various gradations,
e. Manometers connected to the top and bottom of the sample,
j^
f. Graduated cylinder, 100 ml capacity,
g. Thermometer,
h. Stop watch, . .
i. Deaired water,,
j. .Balance sensitive to 0.1 gram, and ,. -. .".- '~ '' ~
k. Drying oven.
2.5.3 Sample Preparation
1. Oven-dry the specimen. Allow it to cool, and weigh to the
nearest 0.1 g. Record the oven-dry weight of material on a
data sheet as Ws. The amount of material should be sufficient
to provide a specimen in the permeameter having a minimum
length of about one to two times the diameter of the specimen.
2. Place a wire screen, with openings small enough to retain
the specimen, over a perforated disk near the bottom of the
permeameter above the inlet. The screen openings should be
approximately equal to the 10 percent size of the specimen.
3. Allow deaired water to enter the water inlet of the
permeameter to a height of about 1/2 in. above the bottom
of the screen, taking care that no air bubbles are trapped
under the screen.
-------
2-9
4. Mix the material thoroughly and place in the permeameter to
avoid segregation. The material should be dropped just at
the water surface, keeping the water surface about 1/2 in.
above the top of the soil during placement. A funnel or a
spoon is convenient for this purpose.
5. The placement procedure outlined above will result in a
saturated specimen of uniform density although in a rela-
tively loose condition. To produce a higher density in the
specimen, the sides of the permeameter containing the soil
sample are tapped uniformly along its circumference and
length with a rubber mallet to produce an increase in
density; however, extreme caution should be exercised so
that fines are not put into suspension and segregated
within the sample. As an alternative to this procedure,
the specimen may be placed using an appropriate sized
funnel or spoon. Compacting the specimen in layers is
not recommended as a film of dust may be formed at the
surface of the compacted layer which might affect the
permeability results. After placement, apply a vacuum
to the top of the specimen and permit water to enter the
evacuated specimen through the base of the permeameter. -
6. After the specimen has been placed, weigh the excess
material, if any, and the container. The specimen weight
is the difference between the original weight of sample and
the weight of the excess material. Care must be taken so
that no material is lost during placement of the specimen.
If there is evidence that material has been lost, oven-dry
the specimen and weigh after the test as a check.
7. -Level the top of the specimen, cover with a wire screen
similar to that used at the base, and fill the remainder of
the permeameter with a filter material.
8. Measure the length of the specimen, inside diameter of the
permeameter, and distance between the centers of the
manometer tubes (L) where they enter the permeameter.
2.5.4 Test Procedure
1. Adjust the height of the constant-head tank to obtain the
desired hydraulic gradient. The hydraulic gradient should
be selected so that the flow through the specimen is lami-
nar. Hydraulic gradients ranging from 0.2 to 0.5 are recom-
mended. Too high a hydraulic gradient may cause turbulent
flow and also result in piping of soils. In general,
coarser soils require lower hydraulic gradients. See
Section 1.5 for further discussion of excessive gradients.
2. Open valve A (see Figure 3a) and record the initial
piezometer readings after the flow has become stable.
Exercise care in building up heads in the permeameter
so that the specimen is not disturbed.
-------
2-10
3. After allowing a few minutes for equilibrium conditions to
be reached, measure by means of a graduated cylinder the
quantity of discharge corresponding to a given time inter-
val. Measure the piezometric heads (h^ and h2> and the
water temperature in the permeameter.
4. Record the quantity of flow, piezometer readings, water
temperature, and the time interval during which the quan-
tity of flow was measured.
2.5.5 Calculations
By plotting the accumulated quantity of outflow versus time on
rectangular coordinate paper, the slope of the linear portion
of the curve can be determined, and the hydraulic conductivity
can be calculated using Equation (8). The value of h in
Equation 8 is the difference between h^ and h2«
2.6 FALLING-HEAD TEST WITH CONVENTIONAL PERMEAMETER
2.6.1 Applicability
The falling-head test can be used for all soil types, but is
usually most widely applicable to materials having low per-
meability. Compacted, remolded, fine-grained soils can be tested
with this method. The method presented is taken from the
Engineering and Design, Laboratory Soils Testing Manual (U.S.
Army, 1980).
2.6.2 Apparatus
The schematic diagram of falling-head permeameter is shown in
Figure 3b. The permeameter consists of the following equipment:
(1) Permeameter cylinder - a transparent acrylic cylinder
having a diameter at least 8 times the diameter of the
largest particles,
(2) Porous disk,
-------
2-11
(3) Wire screen,
(4) Filter materials,
(5) Manometer,
(6) Timing device, and
(7) Thermometer.
2.6.3 Sample Preparation
Sample preparation for coarse-grained soils is similar to that
described previously in Section 2.4.3. For fine-grained
soils, samples are compacted to the desired density using
methods described in ASTM Method D69a-70.
2.6.4 Test Procedure
1. Measure and record the height of the specimen, L, and the
cross-sectional area of the specimen, A.
2. With valve B open (see Figure 3b), crack valve A, and slowly
bring the water level up to the discharge level of the
• permeameterv
3. Raise the head of water in the standpipe above the
discharge level of the permeameter. The difference in head
should not result in an excessively high hydraulic gradient
during the test. Close valves A and B.
4. Begin the test by opening valve B. Start the timer. As
the water flows through the specimen, measure and record
the height of water in the standpipe above the discharge
level, hj, at time t±r and the height of water above the
discharge level, h£ at time t2»
5. Observe and record the temperature of the water in the
permeameter.
2.6.5 Calculations
From the test data, plot the logarithm of head versus time, on
rectangular coordinate paper or use semi-log paper. The slope
of the linear part of the curve is used to determine
-------
2-12
Iogio(hi/h2)/t. Calculate the hydraulic conductivity using
Equation (9).
2.7 MODIFIED COMPACTION PERMEAMETER METHOD
2.7.1 Applicability
This method can be used to determine the hydraulic conductivity
of a wide range of materials. The method is generally used for
remolded fine-grained soils. The method is generally used under
constant-head conditions. The method was taken from Anderson
and Brown, 1981, and EPA (1980).
2.7.2 Apparatus
The apparatus is shown in Figure 4 and consists of the equip-
ment and accessories as follows:
a. Soil Chamber - A compaction mold having a diameter
8 times larger than the diameter of the largest
particles. Typically, ASTM standard mold (Number CN405)
is used,
b. Fluid Chamber - A compaction mold sleeve having the
same diameter as the soil chamber,
c. 2 kg hammer,
d. Rubber rings used for sealing purposes,
e. A coarse porous stone having higher permeability than
the tested sample,
f. Regulated source of compressed air, and
g. Pressure gage or manometer to determine the pressure
on the fluid chamber.
2.7.3 Sample Preparation
1. Obtain sufficient representative soil sample. Air dry the
sample at room temperature. Do not oven dry.
-------
2-13
(2). Thoroughly mix the selected representative sample with
water to obtain a desired moisture content.
(3). Compact the sample to the desired density within the
mold using the method described as part of ASTM Method
D698-70.
(4). Level the surface of the compacted sample with straight
edge, weigh and determine the density of the sample.
(5). Measure the length and diameter of the sample.
(6). Assemble the apparatus, make sure that there are no
leaks, then connect the pressure line to the apparatus.
2.7.4 Test Procedure
(1). Place sufficient volume of water in the fluid chamber
above the soil chamber.
(2). Air pressure must be applied gradually to flush water
through the sample until no air bubbles in the outflow
are observed. For fine-grained soils, the saturation
may take several hours to several days, depending on
the applied pressure.
(3). After the sample is saturated, measure and record the
quantity of outflow versus time.
(4). Record the pressure reading (h) on the top of the fluid
chamber when each reading is made.
(5). Plot the accumulated quantity of outflow versus time on
rectangular coordinate paper.
(6). Stop taking readings as soon as the linear portion of
the curve is defined.
2.7.5 Calculations
The hydraulic conductivity can be calculated using Equation 8.
2.8 TRIAXIAL-CELL METHOD WITH BACK PRESSURE
2.8.1 Applicability
This method is applicable for all soil types, but especially
for fine-grained, compacted, cohesive soils in which full fluid
saturation of the sample is difficult to achieve. Normally,
the test is run under constant-head conditions.
-------
2-14
TO REGULATED PRESSURE SOURCE AND
PRESSURE GAGE OR MANOMETER USED TO
MEASURE H.
~j/\-+—PRESSURE RELEASE VALVE
f^3
mj£^^^^m
TOP PLATE
n^OXVOMX
F J J J ' 1^ .A >
RUBBER "O" RING SEALS
BASEPLATE
1 POROUS STONE
OUTFLOW TO VOLUMETRIC MEASURING DEVICE.
PRESSURE SHOULD BE ATMOSPHERIC OR ZERO
GAGE PRESSURE
Figure 4.--Modified compaction permeameter.
Note: h in Equation 8 is the difference
between the regulated inflow pressure
and the outflow pressure. Source:
Anderson and Brown, 1981.
-------
2-15
2.8.2 Apparatus
The apparatus is similar to conventional triaxial apparatus.
The schematic diagram of this apparatus is shown in Figure 5.
2.8*3 Sample Preparation
Disturbed or undisturbed samples can be tested. Undisturbed
samples must be trimmed to the diameter of the top cap and
base of the triaxial cell. Disturbed samples should be prepared
in the mold using either kneading compaction for fine-grained
soils, or by the pouring and vibrating method for coarse-grained
soils, as discussed in Section 2.5.3.
2,8.4 Test Procedure
(1). Measure the dimensions and weight of the prepared sample.
(2). Place one of the prepared specimens on the base.
(3)- Place a rubber membrane in a membrane stretcher/ turn
both ends of the membrane over the ends of the stretcher,
and apply a vacuum to the stretcher. Carefully lower the
stretcher and membrane over the specimen as shown in
Figure 9. Place the specimen cap on the top of the
specimen and release the vacuum on the membrane stretcher.
Turn the ends of the membrane down around the base and
up around the specimen cap and fasten the ends with O-rings,
(4). Assemble the triaxial chamber and place it in position in
the loading device. Connect the tube from the pressure
reservoir to the base of the triaxial chamber. With
valve C (see Figure 5) on the pressure reservoir closed
and valves A and B open, increase the pressure inside the
reservoir, and allow the pressure fluid to fill the
triaxial chamber. Allow a few drops of the pressure fluid
to escape through the vent valve (valve B) to insure
complete filling of the chamber with fluid. Close valve A
and the vent valve.
-------
2-16
Figure 5.-
-Schematic diagram of typical triaxial compression
apparatus for hydraulic conductivity tests with
back, pressure.
Source: U.S. Army Corps of Engineers, 1970
-------
2-17
(5). Place saturated filter paper disks having the same
diameter as that of the specimen between the specimen and
the base and cap; these disks will also facilitate remo-
val of the specimen after the test. The drainage lines
and the porous inserts should be completely saturated
with deaired water. The drainage lines should be as
short as possible and made of thick-walled, small-bore
tubing to insure minimum elastic changes in volume due to
changes in pressure. Valves in the drainage lines
(valves E, F, and G in Figure 5) should preferably be of
a type which will cause no discernible change of internal
volume when operated. While mounting the specimen in the
compression chamber, care should be exercised to avoid
entrapping any air beneath the membrane or between the
specimen and the base and cap.
(6). Specimens should be completely saturated before any
appreciable consolidation is permitted, for ease and
uniformity of saturation, as well as to allow volume
changes during consolidation to be measured with the
burette; therefore, the difference between the chamber
pressure and the back pressure should not exceed 5 psi -
during the saturation phase. To insure that a specimen
is not prestressed during the saturation phase, the back
pressure must be applied in small increments, with ade-
quate time between increments to permit equalization of
pore water pressure throughout the specimen.
(7). With all valves closed, adjust the pressure regulators to
a chamber pressure of about 7 psi and a back pressure of
about 2 psi. Now open valve A to apply the preset
pressure to the chamber fluid and simultaneously open
valve F to apply the back pressure through the specimen
cap. Immediately open valve G and read and record the
pore pressure at the specimen base. When the measured
pore pressure becomes essentially constant, close valves
F and G and record the burette reading.
(8). Using the technique described in step (3), increase the
chamber pressure and the back pressure in increments,
maintaining the back pressure at about 5 psi less than
the chamber pressure. The size of each increment might
be 5, 10, or even 20 psi, depending on the compressibi-
lity of the soil specimen and the magnitude of the
desired consolidation pressure. Open valve G and measure
the pore pressure at the base immediately upon applica-
tion of each increment of back pressure and observe the
pore pressure until it becomes essentially constant. The
time required for stabilization of the pore pressure may
range from a few minutes to several hours depending on
the permeability of the soil. Continue adding increments
of chamber pressure and back pressure until, under any
increment, the pore pressure reading equals the applied
back pressure immediately upon opening valve G.
-------
2-18
(9). Verify the completeness of saturation by closing valve
F and increasing the chamber pressure by about 5 psi.
The specimen shall not be considered completely
saturated unless the increase in pore pressure imme-
diately equals the increase in chamber pressure.
(10). When the specimen is completely saturated, increase the
chamber pressure with the drainage valves closed to
attain the desired effective consolidation pressure
(chamber pressure minus back pressure). At zero
elapsed time, open valves E and F.
(11). Record time, dial indicator reading, and burette
reading at elapsed times of 0, 15, and 30 sec, 1, 2, 4,
8, and 15 min, and 1, 2, 4, and 8 hr, etc. Plot the
dial indicator readings and burette readings on an
arithmetic scale versus elapsed time .on a log scale.
When the consolidation curves indicate that primary
consolidation is complete, close valves E and F.
(12). Apply a pressure to burette B greater than that in
burette A. The difference between the pressures in
burettes B and A is equal to the head loss (h); h divided
by the height of the specimen after consolidation (L)
is the hydraulic gradient. The difference between the
two pressures should be kept as small as practicable,
consistent with the 'requirement that the rate of flow
be large enough to make accurate measurements of the
quantity of flow within a reasonable period of time.
Because the difference in the two pressures may be very
small in comparison to the pressures at the ends of the
specimen, and because the head loss must be maintained
constant throughout the test, the difference between
the pressures within the burettes must be measured
accurately; a differential pressure gage is very useful
for this purpose. The difference between the eleva-
tions of the water within the burettes should also be
considered (1 in. of water » 0.036 psi of pressure).
(13). Open valves D and F. Record the burette readings at
any zero elapsed time. Make readings of burettes A and
B and of temperature at various elapsed times (the
interval between successive readings depends upon the
permeability of the soil and the dimensions of the
specimen). Plot arithmetically the change in readings
of both burettes versus time. Continue making readings
until the two curves become parallel and straight over
a sufficient length of time to determine accurately the
rate of flow as indicated by the slope of the curves.
-------
2-19
2.8.5 Calculations
The hydraulic conductivity can be calculated using Equation 8.
2.9 PRESSURE-CHAMBER PERMEAMETER METHOD
2.9.1 Applicability
This method can be used to determine hydraulic conductivity of
a wide range of soils, undisturbed and disturbed samples can
be tested under falling-head conditions using this method.
This method is also applicable to both coarse- and fine-grained
soils, including remolded, fine-grained materials.
2.9.2 Apparatus
The apparatus, as shown in Figure 6, consists of
a. pressure chamber,
b. standpipe,
>
c. specimen cap and base, and
d. coarse porous plates.
The .apparatus is capable of applying confining pressure to
simulate field stress conditions.
2.9..3 Sample Preparation
The sample preparation of disturbed and undisturbed conditions
can be prepared in the chamber and enclosed within the rubber
membrane, as discussed in Section 2.8.4.
-------
2-20
MIT
LATMAI.
MVLACI 0^'kIVILINK
Figure 6.-
-Pressure chamber for hydraulic
conductivity.
Sources U.S. Army Corps of Engineers,
1980.
-------
2-21
2.9.4 Test Procedure
(1). By adjusting the leveling bulb, a confining pressure is
applied to the sample such that the stress conditions
represent field conditions. For higher confining
pressure, compressed air may be used.
(2). Allow the sample to consolidate under the applied stress
until the end of primary consolidation.
(3). Flush water through the sample until no indication of
air bubbles is observed. For higher head of water,
compressed air may be used.
(4). Adjust the head of water to attain a desired hydraulic
gradient.
(5). Measure and record the head drop in the standpipe along
with elapsed time until the plot of logarithm of head
versus time is linear for more than three consecutive
readings.
2.9.5 Calculations
The hydraulic conductivity can be determined using Equation 9.
2.10 SOURCES OF ERROR FOR LABORATORY TEST FOR HYDRAULIC
CONDUCTIVITY
There are numerous potential sources of error in laboratory
tests for hydraulic conductivity. Table B summarizes some
potential errors that can occur. Olson and Daniel (1981) pro-
vide a more detailed explanation of sources of these errors and
methods to minimize them. If the hydraulic conductivity does
i
not fall within the expected range for the soil type, as given
in Table C, the measurement should be repeated after checking
the source of error in Table B.
-------
2-22
TABLE B
SUMMARY OP PUBLISHED DATA ON POTENTIAL ERRORS
IN USING DATA FROM
LABORATORY PERMEABILITY TESTS ON SATURATED SOILS
Source of Error and References
Measured K
Too Low or Too High?
1. Voids Formed in Sample Preparation
(Olson and Daniel, 1981).
2. Smear Zone Formed During Trimming
(Olson and Daniel, 1981).
3. Use of Distilled Water as a
Permeant (Fireman, 1944; and
Wilkinson, 1969).
4. Air in Sample (Johnson, 1954).
5. Growth of Micro-organisms
(Allison, 1947).
6. Use of Excessive Hydraulic
Gradient (Schwartzendruber, 1968;
and Mitchell and Younger, 1967).
7. Use of temperature other than the
test temperature.
8. Ignoring Volume Change Due to
Stress Change. (No confining
pressure used).
9. Performing Laboratory Rather
than In-Situ Tests (Olson and
Daniel, 1981).
10. Impedance caused by the test
apparatus, including the
resistance of the screen or
porous stone used to support
the sample.
High
Low
Low
Low
Low
Low or High
Varies
High
Usually low
Low
-------
2-23
2.11 LEACHATE CONDUCTIVITY USING LABORATORY METHODS
Many primary and secondary leachates found at disposal sites
may be nonagueous liquids or aqueous fluids of high ionic
strength. These fluids may significantly alter the intrinsic
permeability of the porous medium. For example, Anderson and
Brown (1981) have demonstrated increases in hydraulic conduc-
tivity of compacted clays of as much as two orders of magnitude
after the passage of a few pore volumes of a wide range of
organic liquids. Consequently, the effects of leachate on these
materials should be evaluated by laboratory testing. The pre-
ceding laboratory methods can all be used to determine leachate
conductivity by using the following guidelines.
2.11.1 Applicability
i
The determination of leachate conductivity may be required for
both fine-grained and coarse-grained materials. Leachates may
either increase or decrease the hydraulic conductivity.
Increases are of concern for compacted clay liners, and
decreases are of concern for drain materials. The applicability
sections of the preceding methods should be used for selecting
an appropriate test for leachate conductivity. The use of the
modified compaction method (Section 2.7) for determining leachate
conductivity is discussed extensively in EPA Publication SW870
(EPA 1980).
-------
2-24
2.11.2 Leachate Used
A supply of leachate must be obtained that is as close in chemi-
cal and physical properties to the anticipated leachate at the
disposal site as possible. Methods for obtaining such leachate
are beyond the scope of this report. However, recent publications
by EPA (1980, SW-87U; 1982, SW-846) and Conway and Malloy (1981)
discuss methodologies for simulating the leaching environment
to obtain such leachate. Procedures for deairing the leachate
supply are given in Section 2.4. The importance of preventing
bacterial growth in leachate tests will depend on the expected
conditions at the disposal site. The chemical and physical
i
properties that may result in corrosion, dissolution, or
encrustation of laboratory hydraulic conductivity apparatus
should be determined prior to conducting a leachate conductivity
test. Properties of particular importance are the pH and the
vapor pressure of the leachate. Both extremely acidic and
basic leachates may corrode materials. In general, apparatus
for leachate conductivity tests should be constructed of inert
materials, such as acrylic plastic, nylon, or teflon. Metal
parts that might come in contact with the leachate should be
avoided. Leachates with high vapor pressures may require
special treatment. Closed systems for fluid supply and pressure
measurement, such as those in the modified triaxial cell methods,
should be used.
2.11.3 Safety
Tests involving the use of leachates should be conducted under
a vented hood, and persons conducting the tests should wear
-------
2-25
appropriate protective clothing and eye protection, standard
laboratory safety procedures such as those as given by
Manufacturing Chemists Association (1971) should be followed.
2.11.4 Procedures
The determination of leachate conductivity should be conducted
immediately following the determination of hydraulic conduc-
tivity (Anderson and Brown, 1981). This procedure maintains
fluid saturation of the sample, and allows a comparison of the
leachate and hydraulic conductivities under the same test
conditions. This procedure requires modifications of test
operations as described below.
2.11.5 Apparatus
In addition to a supply reservoir for water as shown in Figures
%
3 through 6, a supply reservoir for leachate is required.
Changing the inflow to the test cell from water to leachate can
be accomplished by providing a three-way valve in the inflow
line that is connected to each of the reservoirs.
2.11.6 Measurements
Measurements of fluid potential and outflow rates are the same
for leachate conductivity and hydraulic conductivity. If the
leachate does not alter the intrinsic permeability of the
sample, the criteria for the time required to take measurements
is the same for leachate conductivity tests as for hydraulic
conductivity tests. However, if significant changes occur in
the sample by the passage of leachate, measurements should be
-------
2-26
taken until either the shape of a conductivity versus pore
volume curve can be defined, or until the leachate conductivity
exceeds the applicable design value for hydraulic conductivity.
2.11.7 Calculations
If the leachate conductivity approaches a constant value.
Equations 8 and 9 can be used. If the conductivity changes con-
tinuously because of the action of the leachate, the following
modifications should be made. For constant-head tests, the
conductivity should be determined by continuing a plot of
outflow volume versus time for the constant rate part of the
test conducted with water. For falling-head tests, the slope
of the logarithm of head versus time should be continued.
If the slope of either curve continues to change after the flow
of leachate begins, the leachate is altering the intrinsic per-
meability of the sample. The leachate conductivity in this
case is not a constant. In this case, values of the slope of
the outflow curve to use in Equation 8 or 9 must be taken as
the tangent to the appropriate outflow curve at the times of
measurement.
-------
3-1
3.0 FIELD METHODS
This section discusses methods available for the determination
of fluid conductivity under field conditions. As most of these
tests will use water as the testing fluid, either natural for-
mation water or water added to a borehole or piezometer, the
term hydraulic conductivity will be used for the remainder of
this section. However, if field tests are run with leachate or
other fluids, the methods are equally applicable.
The location of wells, selection of screened intervals, and the
k
appropriate tests that are to be conducted depend upon the spe-
cific site under investigation. The person responsible for
such selections should be a qualified hydrogeologist or
geotechnical engineer who is experienced in the application of
established principles of contaminant hydrogeology and ground
water hydraulics. The following are given as general guidelines,
(1). The bottom of the screened interval should be below the
lowest expected water level.
(2). Wells should be screened in the lithologic units that
have the highest probability of either receiving
contaminants or conveying them down gradient.
(3). Wells up gradient and down gradient of sites should be
screened in the same lithologic unit.
Standard reference texts on ground water hydraulics and con-
taminant hydrogeology that should be consulted include: Bear
(1972), Bouwer (1978), Freeze and Cherry (1979), Stallman
(1971), and Walton (1970).
-------
3-2
The success of field methods in determining hydraulic conduc-
tivity is often determined by the design, construction, and
development of the well or borehole used for the tests.
Details of these methods are beyond the scope of this report;
however, important considerations are given in Sections 3.1
and 3.2. Detailed discussions of well installation, construc-
tion, and development methods are given by Bouwer (1978),
pages 160-180, Acker (1974), and Johnson (1972).
The methods for field determination of hydraulic conductivity
are restricted to well or piezometer type tests applicable
below existing water tables. Determination of travel times of
leachate and dissolved solutes above the water table usually
require the application of unsaturated flow theory and methods
which are beyond the scope of this report.
3.1 WELL-CONSTRUCTION CONSIDERATIONS
The purpose of using properly constructed wells for hydraulic
conductivity testing is to assure that test results reflect
conditions in the materials being tested, rather than the con-
ditions caused by well construction, in all cases, diagrams
showing all details of the actual well or borehole constructed
for the test should be made.
3.1.1 Well Installation Methods
Well installation methods are listed below in order of pre-
ference for ground-water testing and monitoring. The order was
determined by the need to minimize side-wall plugging by
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3-3
drilling fluids and to maximize the accurate detection of
saturated zones. This order should be used as a guide/ com-
bined with the judgment of an experienced hydrogeologist in
selecting a drilling method. The combined uses of wells for
hydraulic conductivity testing, water-level monitoring, and
water-quality sampling for organic contaminants were considered
in arriving at the ranking.
a. Hollow-stem auger,
b. Cable tool,
c. Air rotary,
d. Rotary drilling with non-organic drilling fluids,
e. Air foam rotary, and
f. Rotary with organic based drilling fluids.
Although the hollow stem-auger method is usually preferred for
the installation of most shallow wells (less than 100 feet),
care must be taken if the tested zone is very fine. Smearing
of the borehole walls by drilling action can effectively seal
off the borehole from the adjacent formation. Scarification
can be used to remedy this.
3.1.2 Wells Requiring Well Screens
Well screens placed opposite the interval to be tested should
be constructed of materials that are compatible with the fluids
to be encountered. Generally an inert plastic such as PVC is
preferred for ground-water contamination studies. The screen
slot size should be determined to minimize the inflow of fine-
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3-4
grained material to the well during development and testing.
Bouwer (1978), and Johnson (1972) give a summary of guidelines
for sizing well screens.
The annulus between the well screen and the borehole should be
filled with an artificial gravel pack or sand filter.
Guidelines for sizing these materials are given by Johnson
(1972). For very coarse materials, it may be acceptable to
allow the materials from the tested zone to collapse around
the screen forming a natural gravel pack.
The screened interval should be isolated from overlying and -
underlying zones by materials of low hydraulic conductivity.
Generally, a short bentonite plug is placed on top of the
material surrounding the screen, and cement grout is placed in
the borehole to the next higher screened interval (in the case
of multiple screen wells), or to the land surface for single
screen wells.
Although considerations for sampling may dictate minimum casing
and screen diameters, the recommended guideline is that wells
to be tested by pumping, bailing, or injection in coarse-grained
materials should be at least 4-inches inside diameter. Wells
to be used for testing materials of low hydraulic conductivity
by sudden removal or injection of a known volume of fluid should
be constructed with as small a casing diameter as possible to
maximize measurement resolution of fluid level changes. Casing
sizes of 1.25 to 1.50 inches usually allow this resolution
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3-5
while enabling the efficient sudden withdrawal of water for
these tests.
3.1.3 Wells Not Requiring well Screens
If the zone to be tested is sufficiently indurated that a well
screen and casing is not required to prevent caving then, it is
preferable to use a borehole open to .the zone to be tested.
These materials generally are thoae having low to extremely low
hydraulic conductivities. Consolidated rocks having high
conductivity because of the presence of fractures and solution
openings may also be completed without the use of a screen and
gravel pack. Uncased wells may penetrate several zones for
which hydraulic conductivity tests are to be run. In these
cases, the zones of interest can be isolated by the use of
inflatable packers.
3.2 WELL DEVELOPMENT
For wells that are constructed with well screens and gravel
packs, and for all wells in which drilling fluids have been
used that may have penetrated the materials to be tested, ade-
quate development of the well is required to remove these
fluids and to remove the fine-grained materials from the zone
around the .well screen. Development is carried out by methods
such as intermittent pumping, jetting with water, surging, and
bailing. Adequate development is required to assure maximum
communication between .fluids in the -borehole and the zone to be
tested. Results from tests run in wells that ;are inadequately
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3-6
developed will include an error caused by loss of fluid poten-
tial across the undeveloped zone, and computed hydraulic con-
ductivities will be lower than the actual value. Bouwer (1978)
and Johnson (1975) give further details on well development
including methods to determine when adequate development has
occurred.
3.3 DATA INTERPRETATION AND TEST SELECTION CONSIDERATIONS
Hydraulic conductivity may be determined in wells that are
either cased or uncased as described in Section 3.1. The tests
all involve disturbing the existing fluid potential in the
tested zone by withdrawal from or injection of fluid into a
well either as a slug over an extremely short period of time/
or by continuous withdrawal or injection of fluid. The
hydraulic conductivity is determined by measuring the response
of the water level or pressure in the well as a function of
time since the start; of the test. Many excellent references
are available that give the derivation and use of the methods
that are outlined below, including Bouwer (1978), Walton
(1969), and Lohman (1972).
The selection of a particular test method and data analysis
technique requires the consideration of the purposes of the
test, and the geologic framework in which the test is to be
run. Knowledge of the stratigraphic relationships of the zone
to be tested and both overlying and underlying materials should
always be used to select appropriate test design and data
interpretation methods.
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3-7
The equations given for all computational methods given here
and in the above references are based on idealized models
comprising layers of materials of different hydraulic conduc-
tivities. The water-level response caused by disturbing the
system by the addition or removal of water can be similar for
quite different systems. For example, the response of a water-
table aquifer and a leaky, confined aquifer to pumping can be
very similar. Consequently, it is not considered acceptable
practice to obtain data from a hydraulic conductivity test and
interpret the type of hydraulic system present without sup-
porting geologic evidence.
The primary use of hydraulic conductivity data from tests
described subsequently will usually be to aid in siting moni-
toring wells for facility design as well as for compliance with
Subpart F of Part 264. As such, the methods are abbreviated to
provide guidance in determining hydraulic conductivity only.
Additional analyses that may be possible with some methods to
define the storage properties of the aquifer are not included.
The well test methods are discussed under the following two
categories: 1) methods applicable to coarse-grained materials
and tight to extremely tight materials under confined conditions;
and 2) methods applicable to unconfined materials of moderate
permeability. The single well tests integrate the effects of
heterogeneity and anisotropy. The effects of boundaries such
as streams or less permeable materials usually are not detec-
table with these methods because of the small portion of the
geologic unit that is tested.
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3-8
3.4 SINGLE WELL TESTS
The tests for determining hydraulic conductivity with a single
well are discussed below based on methods for confined and
unconfined conditions. The methods are usually called slug
tests because the test involves removing a slug of water
instantaneously from a well and measuring the recovery of water
in the well. The method was first developed by Hvorslev (1951),
whose analysis did not consider the effect of fluid stored in
the well. Cooper and others (1967) developed a method that
considers well bore storage. However, their method only
applies to wells that are open to the entire zone to be tested
and that tap confined aquifers. Because of the rapid water-
level response in coarse materials, the tests are generally
limited to zones with a transmissivity of less than about
70 cm2/sec (Lohman, 1972). The method has been extended to
allow testing of extremely tight formations by Bredehoeft and
papadopulos (1980). Bouwer and Rice (1976) developed a method
for analyzing slug tests for unconfined aquifers.
3.4.1 Method for Moderately Permeable Formations Under
Confined Conditions
3.4.1.1 Applicability. This method is applicable for testing
zones to which the entire zone is open to the well screen or
open borehole. The method usually is used in materials of
moderate hydraulic conductivity which allow measurement of
water-level response over a period of an hour to a few days.
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3-9
More permeable zones can be tested with rapid response water-
level recording equipment. The method assumes that the tested
zone is uniform in all radial directions from the test well.
Figure 7 illustrates the test geometry for this method.
3.4.1.2 Procedures. The slug test is run by utilizing some
method of removing a known volume of water from the well bore
in a very short time period and measuring the recovery of the
water level in the well. The procedures are the same for both
unconfined and confined aquifers. Water is most effectively
removed by using a bailer that has been allowed to fill and -
stand in the well for a sufficiently long period of time so
that any water-level disturbance caused by the insertion of the
bailer will have reached equilibrium. In permeable materials/
this recovery time may be as little as a few minutes. An
alternate method of effecting a sudden change in water level is
the withdrawal of a weighted float. The volume of water
displaced can be computed using the known submersed volume of
the float and Archimedes' principle (Lohman, 1972).
Water-level changes are recorded using either a pressure trans-
ducer and a strip chart recorder, a weighted steel tape, or an
electric water-level probe. For testing permeable materials
that approach or exceed 70 cm2/sec, a rapid-response transducer/
recorder system is usually used because essentially full reco-
very may occur in a few minutes. Because the rate of water-
level response decays with time, water-level or pressure
-------
3-10
i, i
WELL CASING
! i
* WELL SCREEN
I
y/^//^,
/ CONFINING LAYER////
Figure 7.--Geometry and variable definition for
slug tests in confined aquifers.
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3-11
changes should be taken at increments that are approximately
equally spaced in the logarithm of the time since fluid
withdrawal. The test should be continued until the water level
in the well has recovered to at least 85 percent of the initial
pre-test value.
3.1.1.3 Calculations. Calculations for determining hydraulic
conductivity for moderately permeable formations under confined
conditions can be made using the following:
a. Determine the transmissivity of the tested zone by
plotting the ratio h/ho on an arithmetic scale against-
time since removal of water (t) on a logarithmic scale.
The observed fluid potential in the well during the test
as measured by water level or pressure is h, and h0 is
the fluid potential before the instant of fluid
withdrawal. The data plot is superimposed on type
curves, such as those given by Lohman (1972), Plate 2
or plotted from Appendix A with the h/ho and time axes
coincident. The data plot is moved horizontally until
the data fits one of the type curves. A value of time
on the data plot corresponding to a dimensionless time
(8) on the type curve plot is chosen, and the transmis-
sivity is computed from the following:
T * Brc , (10)
t
where rc is the radius of the casing (Lohman, 1972, p. 29)
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3-12
The type curves plotted using data in Appendix A are not
to be confused with those commonly referred to as 'Theis
Curves' which are used for pumping tests in confined
aquifers (Lohraan, 1972). The type curve method is a
general technique of detemining aquifer parameters when
the solution to the descriptive flow equation involves
more than one unknown parameter. Although both the
storage coefficient and transmissivity of the tested
interval can be determined with the type curve method
for slug tests, determination of storage coefficients is
beyond the scope of this report. See Section 3.4.1.4-
for further discussion of the storage coefficient.
If the data in Appendix A are used, a type curve for
each value of a is prepared by plotting F(a,0) on the
arithmetic scale and dimensionless time (3) on the
logarithmic scale of semi-log paper.
i
b. Determine the hydraulic conductivity by dividing the
transmissivity by the thickness of the tested zone.
3.4.1.4 Sources of Error. The errors that can arise in
conducting slug tests can be of three types: those resulting
from the well or borehole construction, measurement errors,
and data analysis error.
Well construction and development errors. This method assumes
that the entire thickness of the zone of interest is open to
-------
3-13
the well screen or boreholes and that flow is principally radial,
If this is not the case, the computed hydraulic conductivity
may be too high. If the well is not properly developed, the
computed conductivity will be too low.
Measurement errors can result from determining or recording the
fluid level in the borehole and the time of measurement
incorrectly. Water levels should be measured to an accuracy of
at least 1 percent of the initial water-level change. For
moderately permeable materials, time should be measured with an
accuracy of fractions of minutes, and for more permeable
materials, the time should be measured in terms of seconds or
fractions of seconds. The latter may require the use of a
rapid-response, pressure transducer and recorder system.
Data analysis errors. The type curve procedure requires
matching the data to one of a family of type curves, described
by the parameter o, which is a measure of the storage in the
well bore and aquifer. Papadopulos and others (1973) show that
an error of two orders of magnitude in the selection of a would
result in an error of less than 30 percent in the value of
transmissivity determined. Assuming no error in determining
the thickness of the zone tested, this is equivalent to a 30
percent error in the hydraulic conductivity.
3.4.2 Methods For Extremely Tight Formations Under
Confined Conditions
3.4.2.1 Applicability. This test is applicable to materials
that have low to extremely low permeability such as silts,
-------
3-14
clays, shales, and indurated lithologic units. The test has
been used to determine hydraulic conductivities of shales of as
low as 10-10 cm/sec.
3.4.2.2 Procedures. The test described by Bredehoeft and
papadopulos (1980) and modified by Neuzil (1982) is conducted
by pressurizing suddenly a packed off zone in a portion of a
borehole or well. The test is conducted using a system such as
shown in Figure 8. The system is filled with water to a level
assumed to be equal to the prevailing water level. This step
is required if sufficiently large times have not elapsed since
the drilling of the well to allow full recovery of water
levels.. A pressure transducer and recorder are used to monitor
pressure changes in the system for a period prior to the test
to obtain pressure trends preceding the test. The system is
pressurized by addition of a known volume of water with a
high-pressure pump. The valve is shut and the pressure decay
is monitored. Neuzil1s modification uses two packers with a
pressure transducer below the bottom packer to measure the
pressure change in the cavity and one between the two packers
to monitor any pressure change caused by leakage around the
bottom packer.
3.4.2.3 Calculations. The modified slug test as developed by
Bredehoeft and Papadopulos (1980) considered compressive
storage of water in the borehole. These authors considered
that the volume of the packed-off borehole did not change
-------
3-15
Prtssure Gage
Systtm Filled
with Water
Pump
Pressure Gage
Land Surface
Initial Head
?-in Tested
Interval
- Tight -
z_ Formatioh^inr:
Valve
System Filled
with Water
Pump
HHHHHHH P ^pr^r^tH:
(a)
(b)
Figure 8.—Schematic diagram for pressurized slug
test method in unconsolidated (a) and
consolidated (b) materials. Source:
Papadopulos and Bredehoeft, 1980.
-------
3-16
during the test and that all compressive storage resulted in
compression of water under the pressure pulse. Neuzil (1980)
demonstrated that under some test conditions this is not a
valid assumption. The computational procedure is the same in
either case. Data is plotted in the same manner as for the
conventional slug test and type curves are used from either
Lohman (1972, Plate 2) or plotted from data given in Appendix A
as described in Section 3.1.1.3. The value of time (t) and
dimensionless time, (0), are determined in the same manner as
for the conventional tests. If compression of water only is
considered, transmissivity is computed by replacing rc2 by the
quantity (Vw C^P g/») in Equation 10:
B(VW \.v MO/"/- (10)
where
Vw is the volume of water in the packed-off cavity, 1,3;
Cw is the compressibility of water, LT2M"1,
p is the density of water ML~3; and
g is the accleration of gravity, LT~2.
If the compressive storage is altered by changing the volume of
the packed-off cavity (V), then the combined compressibility of
the water and the expansion of the cavity (Co) is used. GO is
computed by measuring the volume of water injected during
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3-17
pressurization (AV) and the pressure change AP for the
pressurization:
C0 = — (11)
VAP
(Neuzil, 1982, page 440). Use of Co requires an accurate method
of metering the volume of water injected and the="volume of the
cavity.
3.4.2.4 Sources of Error. The types of errors in this method
are the same as those for the conventional slug test. Errors
may also arise by inaccurate determination of the cavity volume
and volume of water injected. An additional assumption that is
required for this method is that the hydraulic properties of
the interval tested remain constant throughout the test. This
assumption can best be satisfied by limiting the initial
pressure change to a value only sufficiently large enough to
be measured (Bredehoeft and Papadopulos, 1980).
3.4.3 Methods for Moderately Permeable Materials under
Unconfined Conditions
3.4.3.1 Applicability. This method is applicable to wells
that fully or partially penetrate the interval of interest
(Figure 9). The hydraulic conductivity determined will be
principally the value in the horizontal direction (Bouwer and
Rice, 1976).
3.4.3.2 Procedures. A general method for testing cased wells
that partly or fully penetrate aquifers that have a water table
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3-18
WELL CASING
IMPENETRABLE STRATUM
KftWtf/xW&y/'
(b) CASED. NO SCREEN, NO
CAVITY ENLARGEMENT
(a) CASED WITH SCREEN
Figure 9.—Variable definitions for slug tests in
unconfined materials. Cased wells are
open at the bottom.
-------
3-19
as the upper boundary of the zone to be tested was developed by
Bouwer and Rice (1976). The geometry and dimensions that are
required to be known for the method are shown in Figure 9.4 , The
test is accomplished by effecting a sudden change in fluid
potential in the well by withdrawal of either a bailer or sub-
mersed float as discussed in Section 4.4.1.2. Water-level
changes can be monitored with either a pressure transducer and
recorder, a wetted steel tape, or an electric water-level
r
sounder. For highly permeable formations, a rapid-response
transducer and recorder system is required. The resolution of
the transducer should be about 0.01 m.
3.4.3.3 Calculations. The hydraulic conductivity is calcu-
lated using the following equation in the notation of this
report, taken from Bouwer and Rice (1976)
j.n K/r: . v
(12)
Cc ln R/cw in Jo
2 Let Y
where rc, rw, Le, t, Y, and K have been previously defined or
are defined in Figure 8a. Yo is the value of Y immediately
after withdrawal of the slug of water. The term R is an effec-
tive radius that is computed using the following equation given
by Bouwer and Rice (1976).
ln
In (Lw/rw (Le/rw)
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3-20
for wells that do not fully penetrate the aquifer. If the quan-
tity (Ho-Lw)/rw) is larger than 6, a value of 6 should be used.
For wells that completely penetrate the aquifer, the following
equation is used:
In 5- . < —liL. + _£— ) , (14)
rw In (Lw/rw) Wrw
(Bouwer, 1976). The values of the constants A, B, and C are
given by Figure 10 (Bouwer and Rice, 1976).
For both cases, straight-line portions of plots of the
logarithm of Y or YO/Y against time should be used to determine
the slope, In Yo/Y
—^*•» 0
t
Additional methods for tests under unconfined conditions are
summarized by Bower (1976) on pages 117-122. These methods are
modifications of the cased-well method described above that
apply either to an uncased borehole or to a well or piezometer
in which the diameter of the casing and the borehole are the
same (Figures 9b and 9c.)
3.4.3.4 Sources of Error. The method assumes that flow of
water from above is negligible. If this assumption cannot be
met, the conductivities may be in error. Sufficient flow from
the unsaturated zone by drainage would result in a high conduc-
tivity value. Errors caused by measuring water levels and
recording time are similar to those discussed in Sections
3.4.1.4 and 3.4.2.4.
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3-21
A
awl
C
10
2
s n
90 100
8
Jj JO
5OO 1000 5000
L/f...
10. —Carves defining coefficients Ar B,
and C in equations 13 and 14 as
a function of the ratio L/rw.
Source: Bower and Rice, 1976.
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3-22
3.5 MULTIPLE WELL TESTS
Hydraulic conductivity can also be determined by conventional
pumping tests in which water is continuously withdrawn or
injected using one well, and the water-level response is
measured over time in or near more observation wells. These
methods generally test larger portions of aquifers than the
single well tests discussed in Section 4.4. For some cir-
cumstances these tests may be appropriate in obtaining data to
use in satisfying requirements of Part 264 Subpart F. However,
the large possibility for non-uniqueness in interpretation,
problems involved in pumping contaminated fluids, and the
expense of conducting such tests generally preclude their use
in problems of contaminant hydrogeology. The following
references give excellent discussions of the design and
interpretation of these tests: Lohman (1972), Stallman (1971),
and Walton (1970).
3.6 ESTIMATES OF HYDRAULIC CONDUCTIVITY FOR COARSE-GRAINED
MATERIALS
To characterize the ground-water flow system to satisfy the
intent of Part 264 Subpart F, estimates of the hydraulic con-
ductivity based on grain-size analyses, or visual grain-size
classification may be appropriate. However, hydraulic conduc-
tivities determined by these methods are not to be used in per-
mit applications. Several theoretical models are available to
provide these estimates, with one of most widely used being
-------
3-23
Kozeny-Carmen equation which defines the intrinsic permeability,
as adapted from Bear (1972):
,2
- , (15)
180
where n is the effective porosity, and all other terms are as
previously defined.
An empirical approach that has been used by the U.S. Geological
Survey (Lappala, 1978) in several studies relates conductivity
determined by aquifer testing to grain-size, degree of sorting,
and silt content. Table C provides the estimates of hydraulic
conductivity.
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3-24
TABLE C
HYDRAULIC CONDUCTIVITIES ESTIMATED PROM GRAIN-SIZE DESCRIPTIONS
(In Peet Per Day)
Grain-Size Class or Range
From Sample Description
Pine-Grained Materials
Clay
Silt, clayey
Silt, slightly sandy
Silt, moderately sandy
Silt, very sandy
Sandy silt
Silty sand
Sands and Gravels
Very fine sand
Very fine to fine sand
Very fine to medium sand
Very fine to coarse sand
Very fine to very coarse sand
Very fine sand to fine gravel
Very fine sand to medium gravel
Very fine sand to coarse gravel
Fine sand
Fine to medium sand
Pine to coarse sand
Pine to very coarse sand
Pine sand to fine gravel
Pine sand to medium gravel
Pine sand to coarse gravel
Medium sand
Medium to coarse sand
Medium to very coarse sand
Medium sand to fine gravel
Medium sand to medium gravel
Medium sand to coarse gravel
Coarse sand
Coarse to very coarse sand
Coarse sand to fine gravel
Coarse sand to medium gravel
Coarse sand to coarse gravel
Very coarse sand
Very coarse sand to fine gravel
Very coarse sand to medium gravel
Very coarse sand to coarse gravel
Pine gravel
Pine to medium gravel
Pine to coarse gravel
Medium gravel
Medium to coarse gravel
Coarse gravel
Degre
Poor
13
27
36
48
59
76
99
128
27
53
57
70
88
114
145
67
74
84
103
131
164
80
94
116
147
184
107
134
1270
207
160
201
245
241
294
334
e of Sorti
Moderate
Lea
20
27
41-47
-
-
—
-
-
40
67
65-72
—
-
-
-
80
94
98-111
-
-
-
107
134
136-156
-
-
147
214
199-227
-
214
334
289-334
231
468
468
ng
Well
s than
1 - 4
5
7-8
9 - 1
11
13
27
-
-
-
—
-
-
-
53
-
-
-
-
-
94
-
-
-
-
-
134
-
-
-
-
187
-
-
-
267
-
-
401
-
602
Sil
Slight
.001
1
23
24
32
40
51
67
80
107
33
48
53
60
74
94
107
64
72
71
84
114
134
94
94
107
114
134
114
120
147
160 .
227
201
234
241
294
334
t Content
Moderate
19
20
27 -
31
40
52
66
86
27
39
43
47
59
75
87
51
57
61
68
82
108
74
75
88
94
100
94
104
123
132
140
167
189
201
243
284
High
I
13
13
21
24
29
38
49
64
20
30
32
35
44
57
72
40
42
49
52
66
82
53
57
68
74
92
74
87
99
104
107
134
144
160
191
234
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3-25
3.7 CONSOLIDATION TESTS
As originally defined by Terzagi (Terzaghi and Peck, 1967) the
coefficient of consolidation (Cv) of a saturated, compressible,
porous medium is related to the hydraulic conductivity by:
CV -- — , (16)
v
where
K is the hydraulic conductivity, LT"1,
p is the fluid density, ML-3,
g is the gravitational constant, LT-2, and
a is the soil's compressibility, LM~lT2.
The compressibility can be determined in the laboratory with
several types of consolidometers, and is a function of the
applied stress and the previous loading history. Lambe (1951)
describes the testing procedure.
The transfer value of results from this testing procedure is
influenced by the extent to which the laboratory loading simu-
lates field conditions and by the consolidation rate. The
laboratory loadings will probably be less than the stress that
remolded clay liner will experience; therefore, the use of an
already remolded sample in the consolidometer will probably
produce no measurable results. This suggests that the test is
of little utility in determining the hydraulic conductivity of
remolded or compacted, fine-grained soils. Second, the con-
solidation rate determines the length of the testing period.
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3-26
For granular soils, this rate is fairly rapid. For fine-grained
soils, the rate may be sufficiently slow, so that the pre-
viously described methods will provide faster results.
Cohesive soils (clays) must be trimmed from undisturbed samples
to fit the mold, while cohesionless sands can be tested using
disturbed, repacked samples (Freeze and Cherry, 1979).
In general, EPA believes that consolidation tests can provide
useful information for some situations, but prefers the pre-
viously described methods because they are direct measurements
of hydraulic conductivity. Hydraulic conductivity values
determined using consolidation tests are not to be used in per-
mit applications.
%
3.8 FRACTURED MEDIA
Determining the hydraulic properties of fractured media is
always a difficult process. Unlike porous media, Darcy's Law
is not strictly applicable to flow through fractures, although
it often can be applied empirically to large bodies of frac-
tured rock that incorporate many fractures. Describing local
flow conditions in fractured rock often poses considerable dif-
ficulty. Sowers (1981) discusses determinations of hydraulic
conductivity in rock. This reference should be consulted for
guidance in analyzing flow through fractured media.
Fine-grained sediments, such as glacial tills, are commonly
fractured in both saturated and unsaturated settings. These
fractures may be sufficiently interconnected to have a significant
-------
3-27
influence on ground-water flow, or they may be of very limited
connection and be of little practical significance.
Frequently, a laboratory test of a small sample of clay will
determine hydraulic conductivity to be on the order of
10~8 cm/sec. A piezometer test of the same geologic unit over
an interval containing fractures may determine a hydraulic con-
ductivity on the order of perhaps 10~5 or 10"6 cm/sec. To
assess the extent of fracture interconnection, and hence the
overall hydraulic conductivity of the unit, several procedures
can be used. Closely spaced piezometers can be installed; one
can be used as an observation well while water is added to or
withdrawn from the other. Alternately, a tracer might be added
to one piezometer, and the second could be monitored. These,
and other techniques are discussed by Sowers (1981).
For situations that may involve flow through fractured media,
it is important to note in permit applications that an apparent
hydraulic conductivity determined by tests on wells that inter-
sect a small number of fractures may be several orders others
of magnitude lower or higher than the value required to
describe flow through parts of the ground-water system that
involve different fractures and different stress conditions
from those used during the test.
-------
4-1
4.0 CONCLUSION
By following laboratory and field methods discussed or
referenced in this report, the user should be able to determine
the fluid conductivity of materials used for liners, caps,
and drains at waste-disposal facilities, as well as materials
composing the local ground-water flow system. If fluid-
conductivity tests are conducted and interpreted properly/ the
results obtained should provide the level of information
necessary to satisfy applicable requirements under Part 264.
-------
5-1
5.0 REFERENCES
Acker, W. L. , III, Basic procedures for soil sampling and core
drilling, Acker Drill Co., 246 p., 1974.
Allison, L. E., Soil Science, vol. 63, pp. 439-450, 1947.
American Society for Testing and Materials (ASTM), Annual Book
of ASTM Standards, part 19, 1978.
Anderson, D., and K. W. Brown, Organic leachate effects on the
permeability of clay liners, in Proceedings of Solid Waste
Symposium, U.S. EPA, p. 119-lTO", 1981.
Bear, J., Dynamics of fluids in porous media, American Elsevier,
764 p., 1972.
Bouwer, H., Groundwater hydrology, McGraw Hill, 480 p., 1978.
Bouwer, H., and R. C. Rice, A slug test for determining hydraulic
conductivity of unconfined aquifers with completely or
partially penetrating wells, Water Resources Research,
12, p. 423-428, 1976.
Bredehoeft, J. D., and S. S. Papadopulos, A method for deter-
mining the hydraulic properties of tight formations,
Water Resources Research, 16, p. 233-238, 1980.
Corrway, R. A., and B. C. Malloy (eds.), Hazardous Solid Waste
Testing: first conference, ASTM Special Technical
Publication 760, 1981.
Cooper, k. H., J. D. Bredehoeft, and I. S. Papadopulos,
Response of a finite diameter well to an instantaneous
charge of water, Water Resources Research, 3, p. 263-269,
1967.
Fireman, M., Soil Science, vol. 58, pp. 337-355, 1944.
Freeze, R. A., and J. A. Cherry, Groundwater, Prentice Hall,
604 p., 1979.
Gordon, B. B., and M. Forrest, Permeability of soil using con-
taminated permeant, in Permeability and Groundwater
Contaminant Transport, ed. T. F. Zimmie and C. 0. Riggs,
ASTM Special Technical Publication 746, p. 101-120, 1981.
Hillel, D., Soil and Water, Academic Press, 288 p., 1971.
Hvorslev, M. J., Time lag and soil permeability in groundwater
observations, U.S. Army Corps of Engineers Waterways
Experiment Station Bull. 36, 1951.
-------
5-2
Johnson, A. I., Symposium on soil permeability, ASTM STP 163,
American Society of Testing and Materials, Philadelphia,
pp. 98-114, 1954.
Johnson, E. E., Inc., Groundwater and wells, Johnson Division,
UOP, 440 p., 1975.
Lappala, E. G., Quantitative hydrogeology of the Upper
Republican Natural Resources District, Southwest Nebraska,
U.S. Geological Survey Water Resources Investigations 78-38,
Larabe, T. W., Soil testing for engineers, John Wiley, N.Y.,
1951.
Lohman, S. W., Groundwater hydraulics, U.S. Geological Survey
Professional Paper 708, 70 p., 1972.
Lohraan, S. W., and others, Definitions of selected ground
water terms - revisions and conceptual refinements,
U.S. Geological Survey Water Supply Paper 1988, 1972.
» —
Manufacturing Chemists Association, Guide for safety in the
chemical laboratory, Van Nostrand, Reinhold Co., N.Y.,
1971.
Mitchell, A. K., and J. S. Younger, Permeability and capillarity
of soils, ASTM STP 417, American Society for Testing and
Materials, Philadelphia, pp. 106-139, 1967.
Neuzil, C. E., On conducting the modified 'slug1 test in tight
formations, Water Resources Research, vol. 18, no. 2,
pp. 439-441, 1982.
Olsen, R. E., and D. E. Daniel, Measurement of the hydraulic
conductivity of fine-grained soils, in Permeability and
Groundwater Transport, ed. T. F. ZiramTe and C. 0. Riggs,
ASTM Special Publication 746, p. 18-64, 1981.
Papadopulos, S. S., J. D. Bredehoeft, and H. H. Cooper, Jr., On
the analysis of "slug test1 data, Water Resources Research,
9, p. 1087-1089, 1973.
Schwartzendruber, D., Soil Science Society of America Proceed-
ings, vol. 32, no. 1, pp. 11-18, 1968.
Sowers, G. P., Rock permeability or hydraulic conductivity - an
overview, in Permeability and Groundwater Transport, ed.
T. F. ZimmTe and Co. 0. Riggs, ASTM Special Technical
Publication 746, 1981.
Stallman, R. W., Aquifer-test design, observation and data
analysis, TWRI, Chap. Bl, Book 3, U.S. Geological Survey,
U.S. Govt. Printing Office, WAshington, D.C., 1971.
-------
5-3
Terzaghi, K. , and R. B. Peck, Soil Mechanics in Engineering
Practice, 2nd Ed., John Wiley & Sons, N.Y., 729 p., 1967.
Walton, W. C., Groundwater resource evaluation, McGraw Hill, •
664 p., 1970.
Wilkinson, W. B., In situ investigation in soils and rocks,
British and Geotechnical Society, Institution of Civil
Engineers, London, pp. 311-313, 1969.
U.S. Army Corps of Engineers, Laboratory Soil Testing, Water-
ways Experiment Station Publication EMlllO-2-1906, 1970.
U.S. Environmental Protection Agency, Lining of waste impound-
ment and disposal facilities, office of Solid Waste Report
SW-870, 1980.
U.S. Environmental Protection Agency, Hazardous waste guide-
lines and regulations (proposed), Federal Register,
Part IV, Dec. 18, 1978.
U.S. Environmental Protection Agency, Test Methods for Evaluating
Solid Waste, 2nd Edition, SW-846, Superintendent of Documents,
Government Printing Office, Washington, D.C., 1982.
-------
6.0 Appendix A
Values of the function P(o,0) for use in
the conventional and pressurized slug tests.
Source: Papadopulos et.al. (1973)
6-1
JW .-I*" --10-' .-10-* .-10- .-10-
0.001
0.002
0.004
0.008
0.008
0.01
0.02
0.04
0.08
0.08
0.1
0.2
0.4
0.6
0.8
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8,0
9.0
10.0
20.0
30.0
40.0
50.0
60.0
80.0
100.0
200.0
0.9994
0.9989
0.9980
0.9972
0.9984
0.9956
0.9919
0.9848
0.9782
0.9718
0.9855
0.9361
0.8828
0.8345
0.7901
0.7489
0.5800
0.4554
0.3613
0.2893
0.2337
0.1903
0.1562
0.1292
0.1078
0.02720
0.01286
0.008337'
0.006209
0.004961
0.003547
0.002763
0.001313
0.9998
0.9992
0.988ft
0.9978
0.9971
0.9965
0.9934
0.9875
0.9819
0.9785
0.9712
0.9459
0.8995
0.8569
0.8173
0.7801
0.6235
0.5033
0.4093
0.3351
0.2759
0.2285
0.1903
0.1594
0.1343
0.03343
0.01448
0.008898
0.006470
0.005111
0.003617
0.002803
0.001322
0.9998
0.9993
0.9987
0.9982 •
0.9976
0.9971
0.9944
0.9894
0.984ft
0.9799
0.9753
0.9532
0.9122
0.8741
0.8381
0.8045
0.6591
0.5442
0.4517
0.3768
0.3157
0.2655
0.2243
0.1902
0.1620
0.04129
0.01667
0.009637
0.00678*
0.005283
0.003691
0.002845
0.001330
0.9997
0.9994
0.9989
0.9984
0.9980
0.9975
0.9952
0.9908
0.9886
0.9824
0.9784
0.9587
0.9220
0.8875
0.8550
0.8240
0.6889
0.5792
0.4891
0.4146
0.3525
0.3007
0.2573
0.2208
0.1900
0.05071
0.01956
0.01062
0.007193
0.005487
0.003773
0.002890
0.001339
0.9997
0.9995
0.9991
0.9988
0.9982
0.9978
0.9958
0.9919
0.9881
0.9844
0.9807
0.9631
0.9298
0.8984
0.8688
0.8401
0.7139
0.6096
0.5222
0.4487
0.3885
0.3337
0.2888
0.2505
0.2178
0.06149
0.02320
0.01190
0.007709
0.005735
0.003883
0.002938
0.001348
-------
6.0 Appendix A (continued)
Extended values of F(o,B) for use in slug tests.
Source: Bredehoeft and Papadopulos (1980)
6-2
p
C.OoCOOl
C.OOC002
o.oocoo4
O.OQC006
O.OQC008
O.OOC01
o.onco?
o.ooeo4
o.ooco*
o. ope oe
o.ooci
o.onc?
O.OOC4
O.OQC«
o.onca
0.001
O.OOi
0.00*
o.oot
o.ooe
fl.ot
0.02
0.04
0.06
C.OP
0.)
0.2
0.4
0.*
0.8
1.
«.
4.
e.
e.
10.
20.
4C.
*0.
«C.
inc.
?no.
400.
60C.
800.
1000.
a =0.1
0.9993
0.9990
0.9C&6
0.99«2
0.99KO
0.9977
0.9966
0.9955
0.9944
0.9936
•).992fl
0.989H
0.9HSS
0.9P22
•J.9794
0.9769
0.9470
O.S52R
0.9417
0.93?2
0.9236
0.8904
O.»4?l
0.804P
0.7734
0.7459
0.641P
O.S095
0.4227
0.359P
0.3117
0.17ft*
O.OP761
0.05527
0.039*3
0.03065
0.01*06
0.006680
0.004367
0.003?42
O.OP2577
0.001271
C. 000*^07
0.0004143
0.0003140
0.0002510
a =0.2
0.9490
0.94E*
0.99tO
0.947S
0.9971
0.9*46
0.99SS
0.9936
0.9922
0.9909
0.9HS9
0.9857
0.9797
0.9752
0.5713
0.9679
0.9S46
0.93i7
0.9211
0.9069
0.0962
0.65<2
0.7980
0.75*6
0.71SO
0.6665
0.5774
0.44S*
0.364?
0.307?
0.264S
0.1519
0.07496
0.04S9«
o. oatse
0.02670
0.01361
o.oot«;t8
0.00431H
0.003214
0.00?5B9
0.001P66
0.0006296
O.OOC41PP
O.Q003137
o.ooc?«oe
o=OJ&
0.9984
0.9977
0.9968
0.9961
0.9955
0.994S
0.092S
0.9*99
0.9877
0.98SS
0.9»<,i
0.977*
0.9685
0.9615
0.95S7
0.950=
0.9307
0.9031
0.8025
0.86S4
0.850B
O.T947
0.7214
0.6697
0.6289
0.59S1
0.4799
0.3566
0.2«64
0.2397
0.2061
0.1Z02
0.06420
0.04331
0.032S*
0.02600
0.012BR
0.006?74
0.004229
0.003163
0.002526
0.00175R
0.000*272
0.0004177
0.0003131
0.0002S04
a=1
0.9977
0.9968
0.9955
0.9945
0.9936
0.99?9
0.9900
0.9858
0.9827
0.9800
0.9777
0.9687
0.9560
0.9465
O."3ft5
0.9315
0.904B
0.8686
O.«419
0.8202
0.8017
0.7336
0.6489
0.5919
0.5486
0.5137
0.4010
O.?902
0.2311
0.1931
0.1663
0.04912
0.05521
0.03830
0.02933
0.02376
0.01219
0.00*171
0.00413?
0.003105
0.00?487
C. 001247
0.0006242
0.00041A3
0.00031?3
0.0002499
a=2
0.9968
0.9955
0.9936
0.9q?2
0.9910
0.9qOO
0.9AS8
0.9X01
0.9757
0.9720
0.9*86
0.9S62
0.9*89
O.V?56
0.9151
0.9057
0.8702
O.B232
0.7896
0.7626
0.7400
0.6595
0.5*54
0.5055
0.4618
0.4276
0.3234
0.2?92
0.1P17
0.1521
0.1315
O.OB044
0.0466P
0.0^32*
0. 02594
0.02130
0.01133
0.005697
0.003994
0.0030??
0.002431
0.001230
0.0006195
0.0004141
0.0003110
0.0002490
a=5
0.9948
0.9927
0.9B98
0.9876
0.9857
0.9841
0.9776
0.9687
0.9619
0.9562
0.9512
0.9321
0.9061
0.0869
0.8711
0.8576
0.8075
0.7439
0.7001
0.6662
0.6384
0.5450
0.4454
0.3672
0.3469
0.3168
0.2313
0.1612
0.1280
0.1077
0.09375
0.0594Q
0.0362)
0.02663
0.02125
0.0177*
0.009943
0.005395
0.003726
0.002853
0.002313
0.001194
0.0006085
0.0004087
0.0003078
0.0002469
as 10
0.9923
0.9894
0.9853
0.9822
0.9796
0.9773
0.9683
0.9558
0.9464
0.9387
0.9318
0.9059
0.8711
0.8458
0.8253
0.-S079
0.7450
0.6684
0.6178
0.5797
0.5492 "'
0.4517
0.3556
0.3030
0.2682
0.2428
0.1740
0.1207
0.09616
0.08134
0.07120
0.04620
0.02908
0.02185
0.01771
0.01499
0.008716
0.004898
0.003445
0.002666
0.002161
0.001149
0.0005944
0.0004016
0.0003035
0.0002440
-------
APPENDIX B
IMMERSION TEST OF MEMBRAiJE
LINER MATERIALS FOR
COMPATIBILITY WITH WASTES
-------
DRAFT
Method 9082
IMMERSION TEST OF MEMBRANE LINER MATERIALS
FOR COMPATIBILITY WITH WASTES
1.0 Scope and Application
1.1 This test method is for use in determining the effects
upon the physical properties of flexible rner.brane liner
materials intended to contain chemicals in a pit-,
pond, lagoon or landfill-type installation, of the
chemical environment expected to be encountered. Data
from these tests will assist in deciding whether a
•given liner material is acceptable for the' intended
application.
1.2 This method is based on material resulting frorc work by
the National Sanitation Foundation, Dr. Henry E. Haxo,
Dr. Robert Landreth, Matrecon, Inc. and EPA's Municipal
Environmental Research Laboratory in Cincinnati, OH.
2.0 Summary of Method
2.1 In order to estimate long term compatability, the
liner material is exposed to the expected chemical
•
environment for a period of 120 days at an elevated
temperature. A comparison' of the membrane's physical
—-properties before and after this contact period is
used to estimate the properties of the liner at the
time of site closure.
3.0 Interferences
4.0. Apparatus and Materials
4.1 Exposure tank - A size sufficient to contain the samples
-------
they do not touch bottom or sides of the tank, or g*ch
other; for stirring the liquid in the tank; and zor
holding the specimens in such a manner that the lir-jr
material contacts the test solution only on the surface
that would face the waste in an actual disposal site.
%
The tank shall be equipped with a means of maintaining
the solution at a temperature of SQ+2*C and for prevent-
ing, evaporation of the solution (e.g., cover equipped
with a reflux condenser). The Agency understands that
one such device is manufactured by Associated Design
and Manufacturing Company, 814 North Henry Street,
Alexandria, VA 22314, (703)549-5999.
4.2 Stress-strain machine suitable for measuring elongat:^n,
tensile strength, tear and puncture resistance.
4.3 Jig for testing puncture resistance.
4.4 Labels and holders for specimens, of materials known t be
resistant to the specific wastes. Holders of stainless
steel, and tags made of 50 mil polypropylene, eir.bossed
with machinist's numbering dies and fastened with stain-
«
less steel wfre, are resistant to most wastes.
5.0 Reagents
6.0 Sample Collection Preservation and Handling
6.1 For information on what constitutes a representative
sample of the waste fluid to employ, refer to the
appropriate guidance document listed below:
1. RCRA Guidance Document: Surface Impoundments, Liner
Systems, Final Cover, and Freeboard Control. Is-ued
-------
July 1982 and used 'with 40 CfR 254.221(a) and (c),
and 264.228(a).
2. RCRA Guidance Document: Waste Pile Design, Liner
Systems. Issued Julv 1932 ar.d used with 40 CFR
264.251(a), 264.252,*and 264.253.
3. RCRA Guidance Document: Landfill Design, Liner Systems
and Final Cover. Issued Ju.'v 1982 and used with 40
CFR 264.3Cl(a) and 264.310(af.
7.0 Procedure
7.1. Obtain a representative sample of the waste fluid.
7.2 Perform the following tests on uhexposed samples of the
polymeric membrane liner material:
7.2.2 Puncture resistance, thrae specimens
7.2.3 Tensile strength in two c • i'ctions, three speci-
mens in each direction
7.2.4 Elongation at Break, (Thi ; test is only to be
performed on membrane ma.. ="ial which does not
have a fabric or other n n-elastomeric support
on its reverse [away frcT> w *ste] face.)
Tests are to be performed according to the protocols
referenced in Table 9082-1. See Figure 9C82-1 for a
t
suggested cutting pattern.
7.3 Cut pieces of the lining material, of a size to fit sample
holder, and of a sufficient number to permit at least
three samples for each test at each test period.
7.4 Label the test specimens with a plastic identification
tag and suspend in sample of the waste fluid.
7.5 Expose the sample to the stirred waste fluid held at
-------
7.6 At the end of 30, 60, 90 and 120 days of exposure,
remove sufficient specimen from the waste fluid to
determine the merbrane's physical properties (see 7.2).
Place wet specimen \n a labelled container of fresh
waste fluid at room temperature for at least one hour
to effect cooling prior to testing.
7-. 7 Tha sample should 'be tested within 24 hours of removal
from the bath. To test the immersed sample, wipe off any
waste fluid, rinse with deionized water, blot specimen
dry, and measure the physical properties listed in
7.2.
7.8 Results and Reporti;
7.8.1 Plot the cu-ve for each property over the cirr.e
period 0 to 1. 0 days.
7.8.2 Report all ra. tabulated, and plotted data. Evaluation
of the resul
-------
TABLE 9082-1
PHYSICAL PROPERTY TESTING PROCEDURES
[Appropriate ASTM or FTMS(*) Testing Method]
Polymer
?vc
CPE
Butyl rubber
CR
HDPE
EPDM
CO, ECC
CM
PE-SP-A
HDPE -A
L44_/£^ J— I **
CSPE
TN-PVC
T-EPDM
EIA
PVC-CPE
Tensile Strength
& Elongation at Break
D882
D882
D412
D412
D638
D412
D412
. D412
D412
D63b Type IV Dumb ell
at 2 inches/second
D751 Method A
D751 Method A
,
D751 Method A
D751 Method A
'
D882 Method A
Tear
Resistance
D1C04 Die C
D1004 Die C
D624 Die C
Do 2 4 Die C
D1004 Cia C
D624 Die C
D624 Tie C
Co 24 Lie C
D1004 Die C
"""" ' ^ ~ M. ~" * -3
D751 as
modified in
Appendix A
D731 as
modified in
Appendix A
D751 as
modified in
Appendix A
D751 as
modified in
Appendix A
D1104 Die C
Puncture
Resistance
*2065
*2065
*2065
*2065
*2CSS1
*20€5
*2065
• **><"*£ c
*2065
r2C65
*2C65
*2065
*2065
*2065
*2065
Abbreviations:
ASTM: r ''erican Societv for Testina and Materials
I'. tc; .
-------
PVC(Polyvinyl chloride): A synthetic thermoplastic polymer made
by polymerizing vinyl chloride.
CPE (Chlorinated polyethylene): Family of polymers produced by
chemical reaction of chlorine on polyethylene. The resulting
thermoplastic elastomers contain 25 to 45% chlorine by weight
and 0 to 25% crystallinity.
Butyl rubber: A synthetic rubber based on isobutylene and a smalJ
amount of isoprene to provide sites for vulcanization.
CR (Polychloroprene): Generic name for a synthetic rubber based
primarily on on chlorobutadiene.
HDPE (High density polyethylene): A polymer* prepared by the low
pressure polymerization of ethylene as the sole mcnor.er.
EPDM (Ethylene propylene diane mor.cir.ar): A synthetic elastcTer
based on ethylene, propylene, and a small amount of nonce;, ju-
gated diene to provide sites for vulcanization.
CO, ECO (Spichlorohydrin polymers): Synthetic rubber inducing
two epichlorohydrin 'case
1.4% sulfur.
TN-PVC (Thermoplastic nitrile-polyvinyl chloride): An alloy o.
thermoplastic unvulcanized nitriie rubber and polyvir 1
chloride.
T-EPDM (Thermoplastic EPDM): An ethylene-propylene diene monc ar
blend resulting in a thermoplastic elastomer.
EIA (Ethylene interpolymer alloy): A blend of polyethylene n'd
polyvinyl chloride resulting in a thermoplastic elastomer.
PVC-CPE (Polyvinvl chloride - chloroaulfonated oolvethvlene all O*
-------
icr
U.S. Ew>'-.•'•-=- - • /en Agency
Region V,
230 Sou: • • . t
Chicago, liiifiGio
-------
,. r
TEAR RESISTANCE.
TESTjSPECIMENf^
* .^-JWKUKS*. •;-,• -.nay-.-;.-' «v
PUNCTURE RESISTANCE
" ""siIIST_SPECI.MEN "'
Figure 9082-1. Suggested pattern for c tting test specimens
------- |