&EPA
United States
Environmental Protection
Agency
Office of Solid Waste
and Emergency Response
Washington DC 20460
EPA/530-SW-84-016
December 1984
Solid Waste
Draft
Permit Guidance Manual on
Unsaturated Zone Monitoring
for Hazardous Waste
Land Treatment Units
For Public Comment
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DISCLAIMER
This is a draft manual that is being released by EPA for public comment on
the accuracy and usefulness of the information in it. This manual has received
extensive technical review, but the Agency's peer and administrative review
process has not yet been completed. Therefore, it does not necessarily reflect
the views and policies of the Agency. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.
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PREFACE
Subtitle C of the Resource Conservation and Recovery Act (RCRA) requires
the Environmental Protection Agency (EPA) to establish a Federal hazardous
waste management program. This program must ensure that hazardous wastes are
handled safely from generation until final disposition. EPA issued a series of
hazardous waste regulations under Subtitle C of RCRA that is published in 40
Code of Federal Regulations (CFR) 260 through 265, 270 and 124.
Parts 264 and 265 of 40 CFR contain standards applicable to owners and
operators of all facilities that treat, store, or dispose of hazardous wastes.
Wastes are identified or listed as hazardous under 40 CFR Part 261. The Part
264 standards are implemented through permits issued by authorized States or
the EPA in accordance with 40 CFR Part 270 and Part 124 regulations. Land
treatment, storage, and disposal (LTSD) regulations in 40 CFR Part 264 issued
on July 26, 1982, establish performance standards for hazardous waste land-
fills, surface impoundments, land treatment units, and waste piles.
This draft manual provides guidance on unsaturated zone monitoring at
hazardous waste land treatment units for use by permit applicants and permit
writers in developing effective monitoring systems to comply with the Part 264,
Subpart M regulations. This manual covers both soil core and soil pore-liquid
monitoring, and addresses equipment selection, installation» and operation,
sampling procedures, chain of custody considerations, and data evaluation. The
installation and sampling procedures are presented in a step-by-step format so
that the manual may be more readily used by field personnel.
This manual and other EPA guidance documents do not supersede the regula-
tions promulgated under RCRA and published in the Code of Federal Regulations.
They provide guidance, interpretations, suggestions, and references to addi-
tional information. Also, this guidance is not intended to mean that other
designs might not also satisfy the regulatory standards.
EPA intends to revise this manual based on public comments and new infor-
mation generated by EPA research studies. Comments on this manual should be
addressed to the Docket Clerk, Office of Solid Waste (WH-562), U.S. EPA, 401 M
St. SW, Washington, D.C., 20460.
111
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EXECUTIVE SUMMARY
This manual provides guidance on unsaturated zone monitoring at hazardous
waste land treatment units. The manual will be useful to both owners or
operators of hazardous waste land treatment units and officials in implementing
the unsaturated zone monitoring requirements (K264.278) contained in the
hazardous waste land treatment, storage, and disposal regulations (40 CFR 264,
July 26, 1982). After summarizing the regulations, the manual identifies other
available sources of guidance and data on the subject. Complete descriptions
for Darcian and macro-pore flow in the unsaturated zone are given.
Soil core monitoring equipment is divided into hand-held samplers and
power-driven samplers. Specific descriptions for screw-type augers, barrel
augers, post-hole augers, Dutch-type augers, regular or general purpose barrel
augers, sand augers, mud augers, in addition to tube-type samplers, including
soil sampling tubes, Veihmeyer tubes, thin-walled drive samplers, and peat
samplers, are provided. Power-driven samplers, including hand-held power
augers, truck-mounted augers, and tripod-mounted power samplers, are described.
Procedures for selecting soil samplers, site selection, sample number, size,
frequency and depth, sampling procedures, decontamination, safety precautions,
and data analysis and evaluation are presented.
Complete descriptions for soil pore-liquid monitoring are provided.
Relationships between soil moisture and soil tension are fully described. Soil
pore-liquid sampling equipment, including cup-type samplers, cellulose acetate
hollow fiber samplers, membrane filter samplers, and pan lysimeters are pre-
sented. Criteria for selecting soil pore-liquid samplers, site selection,
sample number, size, frequency and depth, installation procedures, and opera-
tion of vacuum-pressure sampling units, are presented. Extensive discussion of
special problems associated with the use of suction lysimeters are included.
Descriptions are provided for pan lysimeter installation and operation, includ-
ing trench lysimeters and free drainage block glass samplers. A discussion is
provided of soil pore-liquid data analysis and evaluation.
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TABLE OF CONTENTS
Page
PREFACE , 111
EXECUTIVE SUMMARY v
LIST OF FIGURES x
LIST OF TABLES xii
ACKNOWLEDGMENTS xlii
1.0 INTRODUCTION 1
1.1 Brief Summary of Regulations 2
1.2 Other Available Guidance 2
1.3 Sources of Data 3
2.0 UNSATURATED ZONE DESCRIPTION 4
2.1 Soil Zone 4
2.2 Intermediate Unsaturated Zone 5
2.3 Capillary Fringe 5
2.4 Flow Regimes 7
2.4.1 Darcian Flow 8
2.4.2 Macropore Flow 8
3.0 SOIL-CORE MONITORING 11
3.1 General Equipment Classification 11
3.1.1 Hand-Held Samplers 11
3.1.1.1 Screw-Type Augers 11
3.1.1.2 Barrel Augers 13
3.1.1.3 Post-Hole Augers 13
3.1.1.4 Dutch-Type Auger 13
3.1.1.5 Regular or General Purpose Barrel Auger .... 13
3.1.1.6 Sand Augers 17
3.1.1.7 Mud Augers 17
3.1.1.8 Tube-Type Samplers 17
3.1.1.8.1 Soil-Sampling Tubes 17
3.1.1.8.2 Veihmeyer Tube 21
3.1.1.8.3 Thin Walled Drive Samplers 21
3.1.1.8.4 Peat Sampler 21
3.1.2 Power-Driven Samplers 25
3.1.2.1 Hand-Held Power Augers 25
3.1.2.2 Truck-Mounted Augers 25
3.1.2.3 Tripod Mounted Power Samplers 25
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TABLE OF CONTENTS
(continued)
Page
3.2 Criteria For Selecting Soil Samplers 25
3.2.1 Capability for Obtaining a Core Sample 25
3.2.2 Soil Types 27
3.2.3 Soil Moisture Content 27
3.2.3.1 Wet Soils 27
3.2.3.2 Dry-Cohesionless Soils 27
3.2.4 Site Accessibility 27
3.2.5 Relative Sample Size 29
3.2.6 Labor Requirements 29
3.2.7 Sampling in Rocky and Stoney Soils 29
3.3 Random Soil-Core Monitoring Site Selection 29
3.4 Sample Number, Size, Frequency and Depths 32
3.4.1 Compositing Samples 36
3.4.1.1 Compositing with a Mixing Cloth 36
3.4.1.2 Compositing with a Mixing Bowl 37
3.5 Sampling Procedure 37
3.5.1 Preliminary Activities 37
3.5.2 Sample Collection With Hand-Held
Equipment '. 39
3.5.2.1 Screw-Type Augers 39
3.5.2.2 Barrel Augers 39
3.5.2.3 Tube-Type Samplers: Soil Probe 40
3.5.2.4 Tube Type Samplers:
Vei hmeyer Tubes 42
3.5.2.5 Thin-Walled Tube Samplers 45
3.5.2.6 Split Spoon Sampler 45
3.5.2.7 Peat Sampler 47
3.5.3 Sample Collection with Power Equipment 48
3.5.3.1 Operation of Power Drilling
Equipment 48
3.5.3.2 Sampling 48
3.5.3.3 Miscellaneous Tools 49
3.6 Decontamination 49
3.6.1 Laboratory Cleanup of Sample Containers 49
3.6.2 Field Decontamination 49
3.7 Safety Precautions 50
3.8 Data Analysis and Evaluation 51
4.0 SOIL-PORE LIQUID MONITORING 55
4.1 Soil Moisture/Tension Relationships 57
4.2 Pore-Liquid Sampling Equipment 59
4.2.1 Ceramic-Type Samplers 59
4.2.2 Cellulose-Acetate Hollow Fiber Samplers 65
4.2.3 Membrane Filter Samplers 65
4.2.4 Pan Lysimeters 68
4.3 Criteria for Selecting Soil-Pore Liquid Samplers 68
4.3.1 Preparation of the Samplers 71
vm
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TABLE OF CONTENTS
(continued)
4.4 Random Pore-Liquid Monitoring Site Selection 72
4.4.1 Surveying in the Locations of Sites and
Site Designations 75
4.5 Sample Number, Size, Frequency and Depths 75
4.6 Installation Procedures for Vacuum-Pressure
Pore-Liquid Samplers 79
4.6.1 Constructing Trenches and Instrument
Shelters 79
4.6.2 Installing Access Lines 81
4.6.3 Step-by-Step Procedures for Installing
Vacuum-Pressure, Pore Liquid Samplers 85
4.6.3.1 Constructing the Hole 85
4.6.3.2 Sampler Installation Procedure 85
4.6.3.3 Bentonite Clay Method 86
4.6.3.4 Backfilling the Trench and Final Survey 86
4.7 Operation of Vacuum-Pressure Sampling Units 88
4.8 Special Problems and Safety Precautions 90
4.8.1 Hydraulic Factors 90
4.8.2 Physical Properties: Soil Texture and
Soil Structure 90
4.8.3 Cup-Wastewater Interactions 91
4.8.3.1 Plugging 91
4.8.3.2 Change in the Composition of Hazardous
Constituents During Movement Through
Pore-Liquid Samplers 92
4.8.4 Climatic Factors 93
4.8.5 Safety Precautions 93
4.8.6 Lysimeter Failure Confirmation 93
4.9 Pan Lysimeter Installation and Operation 94
4.9.1 Trench Lysimeters 94
4.9.2 Free Drainage Glass Block Samplers 96
4.10 Pan Lysimeter Limitations 98
4.11 Data Analysis and Evaluation 98
REFERENCES R-l
APPENDIX A: Table of Random Units A-l
APPENDIX B: Chain of Custody Considerations B-l
APPENDIX C: Example Summary Sheets for Monitoring Results C-l
APPENDIX D: Regulations on Unsaturated Zone Monitoring D-l
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LIST OF FIGURES
Number Page
2-1 Cross Section Through the Unsaturated Zone (Vadose
Zone) and Groundwater Zone 6
3-1 Screw-type Auger/Spiral Auger 12
3-2 Post-Hole Type of Barrel Auger 14
3-3 Dutch Auger 15
3-4 Regular Barrel Auger 16
3-5 Sand Auger 18
3-6 Mud Auger 19
3-7 Soil Sampling Tube 20
3-8 Vei hmeyer Tube 22
3-9 Thin-walled Drive Sampler 23
3-10 Driving Sampling 24
3-11 Soil Core Retainers for Sampling in Very Wet Soils
and Cohesionless Soils, (a) One-Way Solid Flap
Valve, (b) Spring-Type, Segmented Basket Retainer 28
3-12 Random Site Selection Example for Unit cc 31
3-13 Soil Core Sampling Depths 35
3-14 Barrel Auger Sampling Method 41
3-15 Operation of "Backsaver" Handle with Soil
Sampl i ng Tube 43
3-16 Core Sample Extruding Device 46
4-1 Variation of Porosity, Specific Yield, and Specific
Retention with Grain Size 56
4-2 Moisture Retention Curves - Three Soil Types 53
4-3 Soi1-water Sampler 60
4-4 Vacuum-pressure Sampler 62
4-5 Modified Pressure-vacuum Lysimeter 63
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LIST OF FIGURES
(continued)
Number Page
4-6 "Hi/Pressure-vacuum Soil-water Sampler" 64
4-7 Facilities for Sampling Irrigation Return Flow Via
Filter Candles, for Research Project at Tacna, Arizona 66
4-8 Membrane Fi1ter Sampler 67
4-9 Example of a Pan Lysimeter 69
4-10 Free Drainage Glass Block Sampler 70
4-11 Sketch of Land Treatment Site Showing Designations at
Pore-Liquid Sampling Sites 76
4-12 Pore Liquid Sampling Depths 77
4-13 Location of Suction Lysimeters 78
4-14 Views of Trench and Access Shafts at Pore-Liquid
Sampler Sites on Active Land Treatment Site 80
4-15 Above Ground Shelter for Sample Bottles and
Accessories (Side View) 82
4-16 Burial Shelter for Sample Bottle and Accessories 83
4-17 Installation of Access Tubes in a Pressure-Vacuum
Pore-Liquid Sampler 84
4-18 Bentonite Clay Method of Installing Vacuum-Pressure
Pore-Liquid Samplers 87
4-19 Stages in the Collection of a Pore-Liquid Sample
Using a Vacuum-Pressure Sampler 89
4-20 Trench Lysimeters Installed in Trench Shelter 95
4-21 Recommended Pan Lysimeter Installation Procedure 97
XI
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LIST OF TABLES
Number Page
3-1 Criteria for Selecting Soil Sampling Equipment 26
3-2 Summary of Soil-Core Sampling Protocol for Background
and Active Land Treatment Areas 34
3-3 Example Checklist of Materials and Supplies 38
3-4 Personnel Protective Equipment 52
4-1 Summary of Guidance on Pore-Liquid Sampling 73
Xll
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ACKNOWLEDGMENTS
This manual was prepared by L.G. Everett of Kaman Tempo (Santa Barbara,
California 93102) and L.G. Wilson of the University of Arizona (Tucson, Arizona
85721) under Contract Number 68-03-3090 from the U.S. Environmental Protection
Agency, Office of Research and Development. The EPA Project Officer was
L.G. McMillion, Environmental Monitoring Systems Laboratory, Las Vegas, Nevada.
Subsequent to the completion of the manual, the responsibility for completion
of this manual was shifted to the Office of Solid Waste, under the direction of
Mr. Michael Flynn in Washington, D.C. Both Mr. McMillion and Mr. Flynn played
an active role in the manual's preparation.
Dr. William Doucette of TRW, Incorporated, provided an extensive review of
the draft document. Several excellent recommendations were made relative to
non-Darcian flow.
An earlier draft of this manual (6/83) was distributed to the EPA regional
offices for review and comment. In addition, extensive reviews were conducted
at the Environmental Monitoring Support Laboratory in Las Vegas and at the
University of Oklahoma branch of the Groundwater Research Center.
The assistance and cooperation extended by numerous other individuals, not
mentioned above, who were contacted on matters related to this manual, is
gratefully acknowledged.
xiii
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SECTION 1
INTRODUCTION
This document provides guidance on unsaturated zone monitoring at
hazardous waste land treatment units. This guidance will be useful to both
owners or operators of hazardous waste land treatment units and officials in
implementing the unsaturated zone monitoring requirements (§264.278) contained
in the hazardous waste land treatment, storage, and disposal regulations (40
CFR Part 264).
This report stresses the selection and application of unsaturated zone
monitoring equipment. Both soil core and soil pore-liquid monitoring equip-
ment are highlighted. Sampling protocols, including sampling design, fre-
quency, depth, and sample number, are also presented. These protocols (with
minor modifications) are derived from guidance previously issued by EPA (EPA,
1983a; EPA, 1983b). These protocols, which represent interim guidance, are
currently being evaluated in EPA's research program.
Land treatment is a viable management practice for treating and dispos-
ing of some types of hazardous wastes. Land treatment involves the applica-
tion of waste on the soil surface or the incorporation of waste into the
upper layers of the soil (the treatment zone) in order to degrade, transform,
or immobilize hazardous constituents present in hazardous waste. The unsat-
urated zone monitoring program must include procedures to detect both slow
moving hazardous constituents as well as rapidly moving hazardous constitu-
ents. This is best accomplished through a monitoring program including both
soil core and soil pore liquid monitoring. Both soil core monitoring and
soil pore liquid monitoring in the unsaturated zone are discussed in this
report. In addition, the unsaturated zone monitoring requirements (§264.278)
for background and active portions of land treatment units are briefly
reviewed. Procedures for randomly determining the location of soil core and
pore-liquid sampling sites in both the background areas and active portions
are presented. Sampling depth and frequency are fully evaluated. Soil core
monitoring and pore-liquid monitoring equipment are described. Selection
criteria for each of the monitoring apparatus are presented. The field
implementation and operating requirements for each piece of equipment is
presented in a step-by-step format. Sample collection, preservation, stor-
age, chain of custody and shipping are presented.
The unsaturated zone monitoring requirements (§264.278) mentioned above
consist of performance-oriented statements and rules, and, as a result, are
also general in nature. This provides maximum flexibility to the owner or
operator in designing and operating an unsaturated zone monitoring program.
However, the permitting official must render a value judgment on the accepta-
bility of the particular monitoring system design proposed for each land
treatment unit. The purpose of this document is to provide guidance on
essential elements of the unsaturated monitoring program to assist individ-
uals in developing and evaluating these programs. EPA wishes to emphasize
that the specifications in this document are guidance, not regulations.
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Although not addressed in this document, groundwater monitoring is also
required at hazardous waste land treatment units. Requirements pertaining to
groundwater monitoring are provided in Subpart F of Part 264.
1.1 BRIEF SUMMARY OF REGULATIONS
Under the authority of Subtitle C of the Resource Conservation and Recov-
ery Act (RCRA), EPA promulgated interim-final regulations for the treatment,
storage, and disposal of hazardous waste in land disposal facilities on July
26, 1982 (40 CFR, Part 264). Included in these regulations were standards
applicable to hazardous waste land treatment units. Section 264.278 of these
regulations requires that all land treatment units have an unsaturated zone
monitoring program that is capable of determining whether hazardous constitu-
ents have migrated below the treatment zone. Appendix C contains a reprint of
the §264.278 regulations and supporting preamble. The monitoring program must
include both soil-core and soil-pore liquid monitoring. Monitoring for hazard-
ous constituents must be performed on a background plot (until background
levels are established) and immediately below the treatment zone (active
portion). The number, location, and depth of soil-core and soil-pore liquid
samples taken must allow an accurate indication of the quality of soil-pore
liquid and soil below the treatment zone and in the background area. The
regulations require that background values for soil-pore-liquid be based on at
least quarterly sampling for one year on the background plot, whereas back-
ground soil core sampling values may be based on one-time sampling. The
frequency and timing of soil-core and soil-pore liquid sampling on the active
portions must be based on the frequency, time and rate of waste application,
proximity of the treatment zone to groundwater, soil permeability, and amount
of precipitation. The Regional Administrator will specify in the facility
permit the sampling and analytical procedures to be used. The owner or opera-
tor must also determine if statistically significant increases in hazardous
constituents have occurred below the treatment zone. The regulations provide
the option of monitoring for selected indicator hazardous constituents (or
"principal hazardous constituents"), in lieu of all hazardous constituents.
1.2 OTHER AVAILABLE GUIDANCE
Four EPA documents are available which complement the material in this
document on unsaturated zone monitoring. Hazardous Haste Land Treatment
(SW-874) (EPA, 1983a) provides information on site selection, waste charac-
terization, treatment demonstration studies, land treatment unit design,
operation, monitoring, closure, and other topics useful for design and
management of land treatment units. Test Methods for Evaluating Solid Haste
(SW-846) (EPA, 1982b) provides procedures that may be used to evaluate the
characteristics of hazardous waste as defined in 40 CFR Part 261 of the RCRA
regulations. The manual encompasses methods for collecting representative
samples of solid wastes, and for determining the reactivity, corrosivity,
ignitability, and composition of the waste and the mobility of toxic species
present in the waste. The RCRA Guidance Document: Land Treatment Units
(EPA, 1983b) identifies specific designs and operational procedures that EPA
believes accomplish the performance requirements in RCRA Sections 264.272
(treatment demonstration), 264.273 (design and operating requirements),
264.278 (unsaturated zone monitoring), 264.280 (closure and post-closure
care).
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A state-of-the-art document entitled Vadose Zone Monitoring at Hazardous
Waste Sites (Everett et al., 1983) describes the applicability of vadose zone
monitoring techniques to hazardous waste site investigations. Physical,
chemical, geologic, topographic, geohydrologic, and climatic constraints for
vadose zone monitoring are described. Vadose zone monitoring techniques are
categorized for premonitoring, active, and post-closure site assessments.
Conceptual vadose zone monitoring approaches are developed for specific waste
disposal units including waste piles, landfills, impoundments, and land
treatment units.
1.3 SOURCES OF DATA
The main source of soils data is the Soil Conservation Service (Mason,
1982). This Federal agency has offices in each county and also has a main
office for each state. The soil survey reports that are produced by the
agency provide maps, textural, drainage, erosion, and agricultural informa-
tion. In addition to the soil survey reports, each county office usually has
aerial photographs that provide general information on the soils in a parti-
cular area. A local soil scientist often can provide detailed information on
the area around the site.
A second source of soils data can often be obtained from the agricul-
tural schools in each state. The Agronomy or Soils Departments often have
valuable information that is pertinent to the land treatment site. Access to
this data can usually be obtained by contacting the department head or by
contacting the State Cooperative Extension Service office located on the
campus of the university.
A third source of information on soils in an area is found in County and
State Engineering Offices and in the Department of Transportation or Highway
Departments of the states. Local drillers that have worked on construction
projects or have drilled water wells in the area can often provide informa-
tion on the soils and also on sources of information about an area.
Regardless of the source of historic data, however, a recent detailed
assessment of the soils at the particular site should be made by a qualified
soil scientist. This will account for any changes that may have occurred at
the site over the years, and provide the necessary detail to evaluate local
soil conditions.
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SECTION 2
UNSATURATED ZONE DESCRIPTION
Monitoring is carried out at hazardous waste land treatment units for
two primary reasons: (1) to assess the efficiency of the soil processes that
degrade incorporated wastes, and (2) to detect the migration of hazardous
constituents beneath the treatment zone. The "treatment zone" refers to the
area in which all degradation, transformation, or immobilization must occur
(EPA, 1982a). The maximum depth of this zone must be no more than 1.5 m (5
feet) from the initial land surface and at least 1 m (3 feet) above the
seasonal high water table (EPA, 1982a).
The geological profile extending from ground surface (including the
treatment zone) to the upper surface of the principal water-bearing formation
is called the vadose zone. As pointed out by Bouwer (1978), the term "vadose
zone" is preferable to the often-used term "unsaturated zone" because satura-
ted regions are frequently present in the vadose zone. The term "zone of
aeration" is also often used synonymously. In this report we shall use the
term "unsaturated" to be consistent with the terminology used in the regula-
tions. Davis and De Wiest (1966) subdivided the unsaturated zone into three
regions designated as: the soil zone, the intermediate unsaturated zone, and
the capillary fringe.
2.1 SOIL ZONE
The surface soil zone is generally recognized as that region that
manifests the effects of weathering of native geological material. The
movement of water in the soil zone occurs mainly as unsaturated flow caused
by infiltration, percolation, redistribution, and evaporation (Klute, 1965).
In some soils, primarily those containing horizons of low permeability,
saturated regions may develop during waste spreading, creating shallow
perched water tables (Everett, 1980).
The physics of unsaturated soil-water movement has been intensively
studied by soil physicists, agricultural engineers, and microclimatologists.
In fact, copious literature is available on the subject in periodicals
(Journal of the Soil Science Society of America, Soil Science) and books
(Childs, 1969; Kirkham and Powers, 1972; Hillel, 1971, Hillel, 1980; Hanks
and Ashcroft, 1980). Similarly, a number of published references on the
theory of flow in shallow perched water tables are available (Luthin, 1957;
van Schilfgaarde, 1970). Soil chemists and soil microbiologists have also
attempted to quantify chemical-microbiological transformations during soil-
water movement (Bohn, McNeal, and O'Connor, 1979; Rhoades and Bernstein,
1971; Dunlap and McNabb, 1973).
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2.2 INTERMEDIATE UNSATURATED ZONE
Weathered materials of the soil zone may gradually merge with underlying
deposits, which are generally unweathered, comprising the intermediate
unsaturated zone. In some regions, this zone may be practically nonexistent,
the soil zone merging directly with bedrock. In alluvial deposits of western
valleys, however, this zone may be hundreds of feet thick. Figure 2-1 shows
a geologic cross section through an unsaturated zone in an alluvial basin in
California. By the nature of the processes by which such alluvium is laid
down, this zone is unlikely to be uniform throughout, but may contain micro-
or macrolenses of silts and clays interbedding with gravels. Water in the
intermediate unsaturated zone may exist primarily in the unsaturated state,
and in regions receiving little inflow from above, flow velocities may be
negligible. Perched groundwater, however, may develop in the interfacial
deposits of regions containing varying textures. Such perching layers may be
hydraulically connected to ephemeral or perennial stream channels so that,
respectively, temporary or permanent perched water tables may develop.
Alternatively, saturated conditions may develop as a result of deep percola-
tion of water from the soil zone during prolonged surface application.
Studies by McWhorter and Brookman (1972) and Wilson (1971) have shown that
perching layers intercepting downward-moving water may transmit the water
laterally at substantial rates. Thus, these layers serve as underground
spreading regions transmitting water laterally away from the overlying source
area. Eventually, water leaks downward from these layers and may intercept a
substantial area of the water table. Because of dilution and mixing below
the water table, the effects of waste spreading may not be noticeable until a
large volume of the aquifer has been affected.
The number of studies on water movement in the soil zone greatly exceeds
the studies in the intermediate zone. Reasoning from Darcy's equation, Hall
(1955) developed a number of equations to characterize mound (perched ground-
water) development in the intermediate zone. Hall also discusses the hydrau-
lic energy relationships during lateral flow in perched groundwater. Freeze
(1969) attempted to describe the continuum of flow between the soil surface
and underlying saturated water bodies. Bear et al. (1968) described the
requisite conditions for perched groundwater formation when a region of
higher permeability overlies a region of lower permeability in the unsatura-
ted zone.
2.3 CAPILLARY FRINGE
The base of the unsaturated zone, the capillary fringe, merges with
underlying saturated deposits of the principal water-bearing formation. This
zone is not characterized as much by the nature of geological materials as by
the presence of water under conditions of saturation or near saturation.
Studies by Luthin and Day (1955) and Kraijenhoff van deLeur (1962) have shown
that both the hydraulic conductivity and flux may remain high for some vertical
distance in the capillary fringe, depending on the nature of the materials. In
general, the thickness of the capillary fringe is greater in fine materials
than in coarse deposits. Apparently, few studies have been conducted on flow
and chemical transformations in this zone. Taylor and Luthin (1969) reported
on a computer model to characterize transient flow in this zone and compared
results with data from a sand tank model. Freeze and Cherry (1979) indicated
that oil reaching the water table following leakage from a surface source
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900 r
830 -
800
750
700
LU
650
600
550
500
•rrSjSrS' VADOSE ZONE
HYDROGRAPH
-.T.T.TXa^ GROUNDWATER ZONE
11 I I II i 1 I I I 1 I I I I 1 1 I I 1 I 1 11 M I I
^==^rB
4O
45 50 55
YEAR
60 65
pBASE OF AQUIFER ELEVATION 200 FT
Figure 2-1. Cross section through the unsaturated zone (vadose zone)
and groundwater zone (Ayers and Branson, 1973)
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flows in a lateral direction within the capillary fringe in close proximity to
the water table. Because oil and water are immiscible, oil does not penetrate
below the water table, although some dissolution may occur.
The overall thickness of the unsaturated zone is not necessarily con-
stant. For example, as a result of recharge at a water table during a waste
disposal operation, a mound may develop throughout the capillary fringe
extending into the intermediate zone. Such mounds have been observed during
recharge studies (e.g., Wilson, 1971) and efforts have been made to quantify
their growth and dissipation (Hantush, 1967; Bouwer, 1978).
As already indicated, the state of knowledge of water movement and
chemical-microbiological transformations is greater in the soil zone than
elsewhere in the unsaturated zone. Renovation of applied wastewater occurs
primarily in the soil zone. This observation is borne out by the well-known
studies of McMichael and McKee (1966), Parizek et al. (1967), and Sopper and
Kardos (1973). These studies indicate that the soil is essentially a "living
filter" that effectively reduces certain microbiological, physical, and
chemical constituents to safe levels after passage through a relatively short
distance (e.g., Miller, 1973; Thomas, 1973). As a result of such favorable
observations, a certain complacency may have developed with respect to the
need to monitor only in the soil zone.
Dunlap and McNabb (1973)' point out that microbial activity may be
significant in the regions underlying the soil. They recommend that investi-
gations be conducted to quantify the extent that such activity modifies the
nature of pollutants travelling through the intermediate zone.
For the soil zone, numerous analytical techniques were compiled by Black
(1965) into a two-volume series entitled "Methods of Soil Analyses." Moni-
toring in the intermediate zone and capillary fringe will require the exten-
sion of technology developed in both the soil zone and in the groundwater
zone. Examples are already available where this approach has been used. For
example, Apgar and Langmuir (1971) successfully used suction cups developed
for in situ sampling of the soil solution at depths up to 50 feet below a
sanitary landfill. J.R. Meyer (personal communication, 1979) reported that
suction cups were used to sample at depths greater than 100 feet below land
surface at cannery and rock phosphate disposal sites in California.
2.4 FLOW REGIMES
Both soil-core and soil-pore liquid monitoring are required in the
unsaturated zone. These two monitoring procedures are intended to complement
one another. Soil-core monitoring will provide information primarily on the
movement of "slower-moving" hazardous constituents (such as heavy metals),
whereas soil-pore liquid monitoring will provide additional data on the
movement of fast-moving, highly soluble hazardous constituents. Questions
have arisen, however, as to the methods to obtain a soil pore-liquid sample
in a highly structured soil, e.g., clay.
Recent studies have demonstrated that soil water movement in the unsat-
urated zone is considerably more complex than the classical concept and that
rapid infiltration to soil depths not predicted by Darcian flow commonly
-------
occurs in soils with continuous, structural macropores. Thus, a non-Darcian
flow regime capable of transmitting significant quantities of liquid has been
recognized in the unsaturated zone. The results of these studies and the
occurrence of a macropore flow regime indicate distinct limitations to vacuum
operated lysimeters and the potential usefulness of gravity lysimeters for
soil-pore liquid monitoring in highly structured soils or soils with numerous
and continuous macropores (W. Doucette, 1984, personal communication).
Current literature on soil water movement in the unsaturated zone
describes two flow regimes, the classical wetting front infiltration of
Bodman and Colman (1943) and a transport phenomena labeled as flow down
macropore, non-capillary flow, subsurface storm flow, channel flow, and other
descriptive names, but hereafter referred to as macropore flow. The classi-
cal concept of infiltration depicts a distinct, somewhat uniform, wetting
front slowly advancing in a Darcian flow regime after a precipitation event.
The maximum soil moisture content approaches field capacity. Contemporary
models combine this classical concept with the macropore flow phenomena.
2.4.1 Darcian Flow
The fundamental principle of unsaturated and saturated flow is Darcy's
Law. In 1856 Henry Darcy, in a treatise on water supply, reported on experi-
ments of the flow of water through sands. He found that flows were propor-
tional to the head loss and inversely proportional to the thickness of sand
traversed by the water. Considering generalized sand column with a flow rate
Q through a cylinder of cross-sectional area A, Darcy's law can be expressed
as:
Q = KA^ (2-1)
More generally, the velocity
w - Q - K dh (? ?\
V - TT - K. -JT- U-^)
where dh/dL is the hydraulic gradient. The quantity K is a proportionality
constant known as the coefficient of permeability, or hydraulic conductivity.
The velocity in Eq. (2-2) is an apparent one, defined in terms of the' dis-
charge and the gross cross-sectional area of the porous medium. The actual
velocity varies from point to point throughout the column.
Darcy's law is applicable only within the laminar range of flow where
resistive forces govern flow. As velocities increase, inertial forces, and
ultimately turbulent flows, cause deviations from the linear relation of Eq.
(2-2). Fortunately, for most natural groundwater motion, Darcy's law can be
applied.
2.4.2 Macropore Flow
The macropore flow phenomena involves the rapid transmission of free
water through large, continuous pores or channels to depths greater than
predicted by Darcian flow during and/or for a short time period after a
precipitation event. The observation that a significant amount of water
-------
movement can occur in soil macropores was first reported by Lawes et al.
(1882). Reviews of subsequent work are provided by Whipkey (1967) and Thomas
and Phillips (1979). Macropore flow can occur in soils at moisture contents
less than field capacity (Thomas et al., 1978). The depth of macropore flow
penetration is a function of initial water content, the intensity and dura-
tion of the precipitation event and the nature of the macropores (Aubertin,
1971; Quisenberry and Phillips, 1976). Macropores need not extend to the
soil surface for flow down to occur, nor need they be very large or cylin-
drical (Thomas and Phillips, 1979). Exemplifying the role of macropores,
Bouma et al. (1979) reported that planar pores with an effective width of 90
urn occupying a volume of 2.4% were primarily responsible for a relatively
high hydraulic conductivity of 60 cm day" in a clay soil. Aubertin (1971)
found that water can move through macropores very quickly to depths of 10 m
or more in sloping forested soils. Liquid moving in the macropore flow
regime is likely to bypass the soil solution in intraped or matrix pores
surrounding the macropores and result in only partial displacement or disper-
sion of dissolved constituents (Quisenberry and Phillips, 1978; Wild, 1972;
Shuford et al., 1977; Kissel et al., 1973; Bouma and Wosten, 1979; Anderson
and Bouma, 1977).
The current concept of infiltration in well structured soils combines
both classical wetting front movement and macropore flow. Aubertin (1971)
found that the bulk of the soil surrounding the macropores was wetted by
radical movement from the macropores sometime after macropore flow occurred.
A number of researchers have presented mathematical models in an attempt to
explain the macropore flow phenomena (Beven and Germann, 1981; Edwards et
al., 1979; Hoogmoed and Bouma, 1980; Skopp et al., 1981).
Thomas and Phillips (1979) listed four consequences of rapid macropore
flow:
(i) The value of a rain or irrigation to plants will general-
ly not be so high as anticipated since some of the water
may move below the root zone.
(ii) Recharge of groundwater and springs can begin long before
the soil reaches field capacity.
(iii) Some of the salts in the surface of a soil will be moved
to a much greater depth after a rain or irrigation than
predicted by piston displacement. On the other hand,
much of the salt will be bypassed and remain near the
soil surface.
(iv) Because of this, it is not likely that water will carry a
surge of contaminants to groundwater at some time that is
predictable by Darcian theory.
The occurrence of macropore flow poses serious implications for unsatur-
ated zone monitoring and the protection of groundwater from the land treat-
ment of hazardous wastes. The first implication is that contaminated water
may flow rapidly through the treatment zone and not receive full treatment.
Under this short circuit scenario groundwater contamination is probable when
a shallow, well structured soil is underlain by creviced bedrock (e.g.,
-------
limestone solution channels, Shaffer et al., 1979) and/or a high water table
(Anderson and Bouma, 1977). The second implication is that hazardous consti-
tuents moving with the rapid macropore flow may not be detected using suction
lysimetry (W. Doucette, 1984, personal communication).
Only two studies were found to have examined the possibility of suction
lysimeter bypass. Shaffer et al. (1979) found that under wet conditions
typical of wastewater irrigation operations, suction lysimeters did not
sample the majority of water passing the depths of sampler installation. The
suction lysimeters did not have the ability to sample rapidly moving water
which had either a higher or lower ion concentration than the bulk soil
solution. They concluded that vertically installed suction lysimeters are
unsuited to test the composition of leachate water when a highly structured
soil is kept in a high state of water content. Barbee (1983) found that for
structured clay soils in Texas that samples collected by a pan type lysimeter
called a 'glass brick1 were more consistently available and more representa-
tive of a chemical pulse moving in the unsaturated zone than suction lysi-
meters. In both studies the suction lysimetry deficiencies were associated
with the preferential movement of water through macropores at structural unit
boundaries. (Note: Soil structural units are called peds, hence, macropore
flow will occur in interped spaces). Additionally, the macropore flow bypas-
sing the suction lysimeters was collectable in a pan-type lysimeter. Angular
installation of suction lysimeters improves the monitoring efficiency of
these devices in structured soils, but pan lysimeters still more effectively
collect macropore flow that occurs in these soils.
Because of the above concerns, the extent of macropore flow within the
treatment zone of the proposed land treatment site should be fully evaluated
in the treatment demonstration, which is required for all land treatment
units in §264.272 of the regulations. This may be accomplished through a
monitoring program including both suction and pan-type lysimeters. This
evaluation will assist in determining the acceptability of the site for land
treatment and in defining the most appropriate soil pore-liquid monitoring
approach for that site. Owners and operators of sites at which macropore
flow is the dominate flow regime may be unable to demonstrate successful
treatment within the treatment zone.
10
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SECTION 3
SOIL-CORE MONITORING
The purposes of this section are twofold: (1) to describe representa-
tive devices for obtaining soil cores during unsaturated zone monitoring at
land-treatment units, and (2) to describe procedures for obtaining soil
samples using these devices.
3.1 GENERAL EQUIPMENT CLASSIFICATION
Soil samplers are divided into two general groups, namely: (1) hand-
held samplers and (2) power-driven samplers.
3.1.1 Hand-Held Samplers
As suggested by their title, hand-held samplers include all devices for
obtaining soil cores using manual power. Historically, these devices were
developed for obtaining soil samples during agricultural investigations
(e.g., determining soil salinity and soil fertility, characterizing soil
texture, determining soil-water content, etc.) and during engineering studies
(e.g., determining bearing capacity). For convenience of discussion, these
samplers are categorized as follows: (a) screw-type augers, (b) barrel
augers, and (c) tube-type samplers. Soil samples obtained using either the
screw type sampler or barrel augers are disturbed and not truly core samples
as obtained by the tube-type samplers. Nevertheless, the samples are still
suitable for use in detecting the presence of pollutants.
3.1.1.1 Screw-Type Augers--
The screw or flight auger essentially consists of a small diameter
(e.g., li inch) wood auger from which the cutting side flanges and tip have
been removed (Soil Survey Staff 1951). The auger is welded onto a length of
tubing or rod. The upper end of this extension contains a threaded coupling
for attachment to extension rods (Figure 3-1). As many extension rods are
used as required to reach the total monitoring depth. A wooden or metal'
handle fits into a tee-type coupling, screwed into the uppermost extension
rod. During sampling, the handle is twisted manually and the auger literally
screws itself into the soil. Upon removal of the tool, the soil is retained
on the auger flights.
According to the Soil Survey Staff (1951), the spiral part of the auger
should be about 7 inches long, with the distances between flights about the
same as the diameter (e.g., li inches) of the auger to facilitate measuring
the depth of penetration of the tool. The rod portion of the auger and the
extensions are circumscribed by etched marks in even increments (e.g., in
6 inch increments) above the base of the auger.
11
-------
Figure 3-1. Screw-type auger/spiral auger
12
-------
Screw-type augers operate more favorably in wet rather than dry soils.
Sampling in very dry (e.g., powdery) soils may not be possible with these
augers.
3.1.1.2 Barrel Augers—
Basically, barrel augers consist of a short tube or cylinder within
which the soil sample is retained. Components of this sampler consist of
(1) a penetrating bit with cutting edges, (2) the barrel, and (3) two shanks
welded to the barrel at one end and a threaded section at the other end (see
Figure 3-2). Extension rods are attached as required to reach the total
sampling depth. The uppermost extension rod contains a tee-type coupling for
attachment of a handle. The extensions are marked in even depth-wise incre-
ments above the base of the tool.
In operation, the sampler is placed vertically into the soil surface and
turned to advance the tool into the ground. When the barrel is filled, the
unit is withdrawn from the soil cavity and the soil is removed from the
barrel. Barrel augers generally provide a greater sample size than the
spiral type augers.
3.1.1.3 Post-Hole Augers—
The simplest and most readily available barrel auger is the common post-
hole auger (also called the Iwan-type auger, see Acker, 1974). As shown in
Figure 3-2, the barrel part of this auger is not completely solid and the
barrel is slightly tapered toward the cutting bit. The tapered barrel
together with the taper on the penetrating segment help to retain soils
within the barrel.
3.1.1.4 Dutch-Type Auger—
The so-called Dutch-type auger is really a smaller variation of the
post-hole auger design. As shown in Figure 3-3, the pointed bit is attached
to two narrow, curved body segments, welded onto the shanks. The outside
diameter of the barrel is generally only about 3 inches. These tools are
best suited for sampling in heavy (e.g., clay), wet soils.
3.1.1.5 Regular or General Purpose Barrel Auger—
A version of the barrel auger commonly used by soil scientists and
county agents is depicted in Figure 3-4. As shown, the barrel portion of
this auger is completely enclosed. As with the post-hole auger, the cutting
blades are arranged so that the soil is loosened and forced into the barrel
as the unit is rotated and pushed into the soil. Each filling of the barrel
corresponds to a depth of penetration of about 3 to 5 inches (Soil Survey
Staff, 1951). The most popular barrel diameter is 3£ inches, but sizes
ranging from H inches to 5 inches are available (Art's Machine Shop, person-
al communication, 1983).
The cutting blades are arranged to promote the retention of the sample
within the barrel. Extension rods can be made from either standard black
pipe or from light-weight conduit or seamless steel tubing. The extensions
are circumscribed by evenly-spaced marks to facilitate determining sampling
depth.
13
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HANDLE
SHANK
BARREL
BIT
Figure 3-2. Post-hole type of barrel auger
14
-------
Figure 3-3. Dutch auger (Art's Machine Shop, 1982)
15
-------
Cross handles and extensions are
available In two materials and fit all
extendable equipment.
-
H'NC
threaded pin
coupling
Extra strong
baH of
carbon steel,
y«* thick
and1V«"
wide
%" thinwall
lightweight
conduit
Hard drawn
stainless
steel cyfcxler,
smooth sur-
face, wHI not
rust
Forged high-
carbon alloy
steel bits
with steme hard
surfaced
edges, shar-
pened to a
fine cutting
4130 aircraft
quality,
chrome
molybdenum
seamless
tubing
Figure 3-4. Regular auger (Art's Machine Shop, 1982)
16
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3.1.1.6 Sand Augers--
The regular type of barrel auger described in the last paragraphs is
suitable for core sampling in loam type soils. For extremely dry sandy soils
it may be necessary to use a variation of the regular sampler, which includes
a specially-formed penetrating bit to retain the sample in the barrel (Figure
3-5).
3.1.1.7 Mud Augers--
Another variation on the standard barrel auger design is available for
sampling heavy, wet soils or clay soils. As shown in Figure 3-6, the barrel
is designed with open sides to facilitate extraction of the samples. The
penetrating bits are the same as those used on the regular barrel auger
(Art's Machine Shop, personal communication, 1983).
3.1.1.8 Tube-Type Samplers--
Tube-type samplers differ from barrel augers in that the tube-type units
are generally of smaller diameter and their overall length is generally
greater than the barrel augers. These units are not as suitable for sampling
in dense, stoney soils as are the barrel augers. Commonly used varieties of
tube type samplers include soil-sampling tubes, Veihmeyer tubes (also called
King tubes), thin-walled drive samplers, and peat samplers. The tube-type
samplers are preferred if an undisturbed sample is required.
3.1.1.8.1 Soil-sampling tubes—As depicted in Figure 3-7, soil-sampling
tubes consist of a hardened cutting tip, a cut-away barrel, and an uppermost
threaded segment. The tube is attached to sections of tubing to attain the
requisite sampling depth. A cross-handle is attached to the uppermost
segment.
The cut-away barrel is designed to facilitate examining soil layering
and to allow for the easy removal of soil samples. Generally, the tubes are
constructed from high strength alloy steel (Clements Associates Inc., 1983).
The sampler is available in three common lengths, namely, 12 inches, 15 inch-
es, and 18 inches. Two modified versions of the tip are available for
sampling either in wet or dry soils. Depending on the type of cutting edge,
the tube samplers obtain samples varying in diameter from 11/16 inches to 3/4
inches.
Extension rods are manufactured from light-weight, durable metal.
Extensions are available in a variety of lengths depending on the manufac-
turer. Markings on the extensions facilitate determining sample depths.
Sampling with these units requires forcing the tube in vertical incre-
ments into the soil. When the tube is filled at each depth the handle is
twisted and the assembly is then pulled to the surface. Commercial units are
available with attachments which allow foot pressure to be applied to force
the sampler into the ground.
17
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Figure 3-5. Sand auger (Art's Machine Shop, 1982)
L£
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Figure 3-6. Mud auger (Art's Machine Shop, 1982)
19
-------
Figure 3-7.
Soil sampling tube
Inc., 1983)
(Clements Associates,
20
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3.1.1.8.2 Veihmeyer tube—In contrast to the soil probe, the Veihmeyer
tube consists of a long, solid tube which is driven to the required sampling
depth. Components of the Veihmeyer tube are depicted in Figure 3-8. As
shown, these units consist of a bevelled tip which is threaded into the body
tube. The upper end of the cylinder is threaded into a drive head. A
weighted drive hammer fits into the tube to facilitate driving the sampler
into the soil. Slots in the hammer head fit into ears on the drive head.
Pulling or jerking up on the hammer forces the sampler out of the cavity.
The components of this sampler are constructed from hardened metal. The
tube is generally marked in even, depth-wise increments.
3.1.1.8.3 Thin walled drive samplers—In some circumstances, it may be
desirable to obtain a relatively "undisturbed" sample from beneath the treat-
ment zone. The sampling tubes described in the previous sections may be
suitable in most cases. An alternative method is to use the so-called
thin-walled drive samplers. A common variety of these samplers is depicted
in Figure 3-9. As shown, the tool consists of a thin-walled seamless steel
tube, with a bevelled cutting tip, and a head unit threaded to fit a standard
drill rod. The head contains a ball check valve for releasing air from the
cylinder during sampling. An alternate version, which facilitates examining
and removing the sample, is the split-tube sampler. In this unit the barrel
of the sampler is split longitudinally. During sampling, the two halves are
placed together and a hardened shoe with a cutting tip is threaded onto one
end of the tube and the drive head assembly is screwed onto the other end.
Some split-spoon samplers are available with a solid barrel which houses a
thin-walled split shell.
The tubes are available in diameters ranging from 2 inches to 5 inches
O.D., although 3 inch O.D. seems to be quite popular. Similarly, the most
commonly-used tubing length is 18 inches (Acker, 1974).
In operation, these samplers are attached to the drill rod and the
assembly is lowered to the base of a cavity excavated by an auger. The tube
is then forced into the undisturbed soil. Figure 3-10 illustrates one method
for pushing the sampler into the soil using a drive weight. The drive weight
can be raised and dropped either by hand using a tripod or pulley arrange-
ment, or by a power-driven hoist.
3.1.1.8.4 Peat sampler—At some sites, the soils may be sufficiently
saturated with organics that the Davis peat sampler may be required to
extract a sample. This unit consists of a sampling tube and an internal
plunger containing a cone-shaped point, which extends beyond the sampling
tube, and spring catch at the upper end. Prior to sampling, the unit is
forced to the required depth, then the internal plunger is withdrawn by
releasing the spring catch via an actuating rod assembly. The next step is
to force the cylinder down and the undisturbed soil to the required depth,
and then withdrawing the assembly with the collected sample. According to
Acker (1974), the sample removed is 3/4 inch diameter and 5i inches in
length.
21
-------
drive hammer
n
head
tube
J
point
Figure 3-8. Veihmeyer tube
22
-------
MEAO.MCOLE SECTION 7 ,V«LVE, RUBBER SEAT
/SCREW
/ • ,^M6aO. BOTTOM SECTION
VWLL TUBE
Figure 3-9. Thin-walled drive sampler
23
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DRIVE COUPLING
DRIVE SHOE
SPLIT TUBE SAMPLER.
IN UNDISTURBED SOIL
Figure 3-10. Driving sampling (Acker, 1974)
24
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3.1.2 Power-Driven Samplers
Inasmuch as the maximum depth required for soil-core sampling at land-
treatment sites is only 6 feet, the hand-held units described in the previous
section will probably be adequate in most cases. For some special situa-
tions, however, it may be necessary to utilize power-driven augers or hoists.
3.1.2.1 Hand-Held Power Augers—
A very simple, commercially available auger consists of a flight auger
attached to and driven by a small air-cooled engine. A set of two handles
are attached to the head assembly to allow two operators to guide the auger
into the soil. Throttle and clutch controls are integrated into grips on the
handles.
3.1.2.2 Truck-Mounted Augers-
Small drill rigs are commercially available for mounting on a pickup
truck. Similar units may be constructed in a machine shop (Kelley et al.,
1947). The tower which supports the drive head and drill rod folds down into
a horizontal position during transport. These units are commonly used with
flight augers for sampling, although drive samplers can be obtained using a
cathead hoist.
3.1.2.3 Tripod Mounted Power Samplers--
Drive samples can be obtained using a commercially-available motorized
cathead hoist (Acker, 1974). This unit consists of an engine mounted near
the base of one leg of the tripod and a cathead assembly. One section of a
manila rope is wound around the cathead and passed through a pulley attached
to the top of the tripod. The end of this section is attached to the drive
assembly of the sampler. The other end of the manila rope is used to tighten
or release the rope wound around the cathead to raise and lower the sampler
unit.
3.2 CRITERIA FOR SELECTING SOIL SAMPLERS
Important criteria to consider when selecting soil-sampling tools for
soil monitoring at land treatment units include: (1) capability for obtain-
ing a core sample, (2) suitability for sampling various soil types, (3) suit-
ability for sampling soils under various moisture conditions, (4) accessi-
bility to sampling site during poor on-site surface conditions, (5) relative
sample size obtained, and (6) labor requirements. Each of the sampling
techniques described in the previous sections were evaluated for these
criterion and the results are summarized in Table 3-1. This section briefly
reviews each of the selection criteria.
3.2.1 Capability for Obtaining a Core Sample
The RCRA requirements specify soil-core sampling for hazardous waste
land treatment units. The intent of the regulations was not to limit the
techniques to "cores" just soils which are representative of those below the
treatment zone. Strictly speaking, screw-type augers and barrel augers do not
obtain soil cores. Nevertheless, provided they obtain representative samples,
25
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TABLE 3-1. CRITERIA FOR SELECTING SOIL SAMPLING EQUIPMENT
cr>
Type of Sampler
A. Hand Auger
1. Screw-Type Augers
2. Barrel Augers
a. Post-Hole Auger
b. Dutch Auger
c. Regular Barrel Auger
d. Sand Augers
e. Mud Augers
Obtains Core Most Suitable Operation in
Sample Core Types Stoney Soils
Yes No Coh Coh'less Eit Fav Unfav
X XX
XX X
XX X
XX X
XX X
X X X
Most Suitable
Soil Moisture
Conditions
Wet Dry Inter
X
X
X
X
X
X
Access, to Sampl.
Sites During Poor Relative Labor Req'mts
Soil Conditions Sample Size Sngl 2/More
Yes No Sm Lg
XXX
X XX
X X x
X XX
X XX
3. Tube-Type Samplers
a. Soil Probes
(1) Wet Tips
(2) Dry Tips
b. Yeihmeyer Tubes
c. Thin-Walled Tube Samplers
d. Peat Samplers
B. Power Auger
1. Hand-Held Screw Type Power Auger
2. Truck Mounted Auger
a. Screw Type
b. Drive Sampler
3. Tripod Mounted Drive Sampler
X
X
X X
X X
X
XXX X X x *
X X XX
X X X x X
XX X X X
XX XX X x
X
X
X X
X X
XXX XX X
X XXX X
XXX X
-------
these units can be used to obtain soil samples from the requisite
monitoring depth.
3.2.2 Soil Types
Land treatment sites located on soils of intermediate texture (i.e.,
loams), require the use of regular augers. The soils below the treatment
zone may be predominately either cohesive (e.g., clay types) or cohesionless
(e.g, sands). For either of these extreme conditions some tools are more
effective than others for obtaining and retaining the samples. Alterna-
tively, special tools are available when either of these conditions is
encountered. For example, sand augers are a variation of the standard barrel
auger designed for sampling in cohesionless soils. Similarly, Dutch augers
and mud augers are best suited for cohesive soils.
As described in a later section, special attachments, called core
catchers, are available to assist in retaining core samples in thin-walled
samplers when dry cohesionless soils are being sampled.
3.2.3 Soil Moisture Content
3.2.3.1 Wet Soils-
It may be difficult to retain soil samples within a sampler in very wet,
sticky soils. Hand-held samplers which are particularly suited for such
soils include Dutch augers, mud augers, and special soil sampling tubes.
Thin-walled drive samplers with built in sampler retainers could also be
used.
Peat samplers are designed for sampling in wet, organic soils. The
operating principles of each of these units were described in previous
sections of this chapter.
3.2.3.2 Dry-Cohesionless Soils—
As with saturated samples, it may not be possible to retain samples of
very dry, cohesionless soils within a sampler. Sand augers and specially
designed soil-sampling tubes are useful for sampling in these soils. Alter-
natively, thin-walled drive samplers with sample retainers, or "core catch-
ers" could be used. Two types of sample retainers, shown in Figure 3-11,
include a one-way solid flap valve, and a segmented, spring-type basket
retainer. Core catchers are inserted inside the sampler between the shoe and
the sample barrel.
3.2.4 Site Accessibility
Generally, site accessibility refers to the ease of reaching on-field
monitoring sites. Specifically, the surface soils at a field may become
virtually intractable following liquid waste application or after a heavy
rainfall. For such conditions, power-driven units mounted in pickup trucks
cannot be used, whereas, an operator may (albeit with difficulty) be able to
reach the site on foot with the sampling equipment.
27
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(o)
(b)
Figure 3-11.
Soil core retainers for sampling in very wet soils
and cohesionless soils, (a) One-way solid flap
valve, (b) Spring-type, segmented basket retainer
28
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3.2.5 Relative Sample Size
A review of the discussion on sampling tools will show that the sample
size obtained by the different samplers varies. For example, hand-driven
screw-type augers generally obtain samples from a bore hole which is less
than 2 inches in diameter, whereas, barrel augers are available for obtaining
5 inch cores. The choice of a unit may be based on sample size requirements.
The number and kind of analysis to be done on the soil sample will determine
the volume of sample required. In addition, in rocky and stoney soils larger
units may be necessary to obtain a useable mass of sample once the rocks have
been discarded.
3.2.6 Labor Requirements
Generally speaking, it is good practice to send at least two individuals
into the field to obtain samples. That is, hand-sampling is often tedious
and two individuals can take turns on the sampler. In addition, note-taking
and sample labelling is facilitated when two individuals are involved.
Strictly speaking, however, the majority of sampling tools only require the
presence of one individual, the exception being where power equipment is
used.
3.2.7 Sampling in Rocky and Stoney Soils
Rocky or stoney soils in the treatment zone will generally impede the
progress of most tools. The problem will be accentuated with small diameter
tools such as soil probes. Alternate tools, such as larger diameter barrel
augers, may be necessary.
3.3 RANDOM SOIL-CORE MONITORING SITE SELECTION
The RCRA Guidance Document on Land Treatment Units recommends that
soil-core monitoring sites be randomly selected (EPA, 1983b). If n random
sites are to be selected, a simple random sample is defined as a sample
obtained in such a manner that each possible combination of n sites has an
equal chance of being selected. In practice, each site is selected separ-
ately, randomly, and independently of any sites previously drawn. For
soil-core monitoring, each site to be included in the "sample" is a volume of
soil (soil core).
It should be recognized that adjacent sampling points on a landscape are
more often than not spatially dependent. The theory for spatial dependence,
known as regionalized variable theory holds that the difference in value for
a specific property depends upon the distance between measurement locations
and their orientation in the landscape. Geostatistics, the application of
regionalized variable theory, has been employed to demonstrate a number of
spatial relationships for both soil chemical and physical properties. For
many properties, a geostatistic analysis will indicate an approximate dis-
tance between two observations for which those observations are expected to
be independent (no co-variance). Observations at a closer spacing are
expected to be dependent to some degree. A strictly random sampling scheme
as presented by EPA (1983a, 1983b) assumes independence between sample
locations. This sampling scheme has been slightly modified in this guidance
to maintain the assumption of independence between sampling locations. The
29
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following sampling scheme specifies that sample point separations should be
in excess of 10 meters.
It is convenient to spot the field location for soil-coring devices by
selecting random distances on a coordinate system and using the intersection
of the two random distances on a coordinate system as the location at which a
soil core should be taken (see Figure 3-12). This system works well for
fields of both regular and irregular shape, since the points outside the area
of interest are merely discarded, and only the points inside the area are
used in the sample.
The location, within a given uniform area of a land treatment unit
(i.e., active portion monitoring), at which a soil core should be taken
should be determined using the following procedure as described by EPA
(1983a, 1983b):
(1) Divide the land treatment unit (Figure 3-12) into uniform
areas (aa, bb, cc, dd). A uniform area is an area of the
active portion of a land treatment unit which is composed of
soils of the same soil series and to which similar wastes or
waste mixtures are applied at similar application rates.
Swales are treated as a different uniform area and are discus-
sed in Hazardous Waste Land Treatment (EPA, 1983a) under the
heading of "hot spots."A qualified soil scientist should be
consulted in completing this step.
(2) Map each uniform area by establishing two base lines (0-A and
0-B) at right angles to each other which intersect at an
arbitrarily selected origin (0), for example, the southwest
corner. Each baseline should extend to the boundary of the
uniform area.
(3) Establish a scale interval (e.g., 100 m) along each base line.
The units of this scale may be feet, yards, miles, or other
units depending on the size of the uniform area. Both base
lines must have the same scale.
(4) Draw two random numbers from a random numbers table (see
Appendix A). Use these numbers to locate one point along each
of the base lines.
(5) Locate the intersection of two lines drawn perpendicular to
these two base line points. This intersection (•) represents
one randomly selected location for collection of one soil
core. If this location at the intersection is outside the
uniform area (x), or within 10 m of another sampling location,
disregard this sampling location and repeat the above
procedure.
30
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R-65W-I R-64W-
LAND TREATMENT BORDER
• USEABLESITE
x DISCARD SITE
SCALE 1: 20,000
SOILSERIESaa, bb, cc, dd
Figure 3-12. Random Site (§) selection example for unit cc
31
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(6) For soil-core monitoring, repeat the above procedure as many
times as necessary to obtain six soil coring locations within
each uniform area of the land treatment unit. If a uniform
area is greater than twelve acres, repeat the above procedure
as necessary to provide at least two soil coring locations per
four acres. (If the same location is selected twice, disre-
gard the second selection and repeat as necessary to obtain
different locations). This procedure for randomly selecting
soil coring locations must be repeated at each sampling event
(i.e., semi-annually).
Locations for monitoring on background areas should be randomly deter-
mined using the following procedure:
(1) Consult a qualified soil scientist in determining an accep-
table background area. The background area must have charac-
teristics (i.e., at least soil series classification) similar
to those present in the uniform area of the land treatment
unit it is representing.
(2) Map an arbitrarily selected portion of the background area
(preferably the same size as the uniform area) by establishing
two base lines at right angles to each other which intersect
at an arbitrarily selected origin.
(3) Complete steps 3, 4, and 5 as defined above.
(4) For soil-core monitoring, repeat this procedure as necessary
to obtain eight soil coring locations within each background
area (see Table 3-2).
3.4 SAMPLE NUMBER, SIZE, FREQUENCY AND DEPTHS
Sample number in research designs is typically decided based on a
liberal estimate of the variance for a constituent as it is distributed
spatially, a specified detection increment (e.g., 5 ppb) and a confidence
level for the detection increment. The problem in recommending a set number
of samples per sampling event is simply that the variance of a sampling event
and/or background study may be sufficiently large to preclude an inference
that a statistical difference exists with any confidence. A more appropriate
and statistically supportable approach is to set the detection increment per
hazardous constituent and the confidence level. The applicant would be
required to perform a background study of variability as the basis for
determining the number of samples per sampling event. Because this approach
is still being evaluated by EPA research, EPA has chosen to provide interim
guidance based upon the best judgement of scientists familiar with land
treatment units. This interim guidance recommends a specified number of
samples, size, frequency and depth per sampling event for both the background
soil series and the uniform areas of the active land treatment unit (EPA,
1983b). This guidance may be revised when EPA research studies are
completed.
Background concentrations of hazardous constituents should be establish-
ed using the following procedures.
32
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TABLE 3-2. SUMMARY OF SOIL-CORE SAMPLING PROTOCOL FOR BACKGROUND AND ACTIVE LAND TREATMENT AREAS
Sampling
Area
Number of
Randomly
Selected
Core Samples
Number of
Samples per
Composite
Total Number
of Composited
Samples
Sampling
Depth
Sampling
Frequency
CO
GO
1. Background, In soils with
similar mapping character-
istics in active area
2. Active land treatment area
a. Uniform area less than
5 hectares (12 acres)
b. Uniform area greater
than 5 hectares
(12 acres)
2 per 1.5 hectares
(4 acres)
6 per 5 hectares
(12 acres)
3 per 5 hectares
(12 acres)
within 6-in depth
below treatment zone
on active zone
Within treatment zone
for determination of pH
Within 6-in region below
treatment zone for PHC's
Within treatment zone
for determination of pH
Within 6-in region below
treatment zone for PHC's
one time
Semi annually
Semi annually
-------
(1) Take at least eight randomly selected soil cores for each soil
series present in the treatment zone from similar soils where
waste has not been applied. The recommended soil series
classification is defined in the 1975 USDA soil classification
system (Soil Conservation Service, 1975). The cores should
penetrate to a depth below the treatment zone but no greater
than 15 centimeters (6 inches) below the treatment zone
(Figure 3-13).
(2) Obtain one sample from each soil-core portion taken below the
treatment zone.
(3) Composite the soil-core samples from each soil series to form
a minimum of four composite samples for each soil series
(i.e., randomly composite two soil-core samples to form a
composite sample; since eight core samples per soil series
were taken, a total of four composite samples will be formed).
The active portion of a land treatment unit can be sampled according to
the following procedures:
(1) The owner or operator should take at least six randomly
selected soil cores per uniform area, semi-annually. However,
if a uniform area is greater than 5 hectares (12 acres), at
least two randomly selected soil cores per 1.5 hectares (4
acres) should be taken semi-annually. The cores should
penetrate to a depth below the treatment zone but no greater
than 15 centimeters (6 inches) below the treatment zone
(Figure 3-13).
(2) The pH of the treatment zone in each uniform area should be
determined using the following procedure:
a. Obtain one representative sample from each soil-core
portion taken within the treatment zone.
b. Composite the soil-core samples from each uniform area to
form a minimum of three composite samples for each
uniform area. However, if a uniform area is greater than
5 hectares (12 acres), a minimum of one composite sample
per 1.5 hectares (4 acres) should be formed.
(3) The concentrations of hazardous constituents below the treat-
ment zone in each uniform area should be determined using the
following procedure :
a. Obtain one sample from each soil-core portion taken below
the treatment zone (Figure 3-13).
b. Composite the soil-core samples from each uniform area to
form a minimum of three composite samples for each
uniform area. However, if a uniform area is greater than
5 hectares (12 acres), a minimum of one composite sample
per 1.5 hectares (4 acres) should be formed.
34
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BACKGROUND
8 SOIL CORES FOR EACH SOIL SERIES
INITIAL SOIL SURFACE
fc»n^
\
ACTIVE
6 SOIL CORES PER UNIFORM AREA
to
en
/
^B
F
15 cm (6 in)
RANDOMLY COMPOSITE 2 SOIL-
CORE SAMPLES TO GET
4 SAMPLES PER SOIL SERIES
\7 SEASON/
j
TREATMENT ZONE /
i
/
RANDOMLY COMPOSITE IN
PAIRS TO GET 3 SAMPLES
PER UNIFORM AREA
1\
L i-\
15 cm (6 in)
I
I
•
•
J
1.J
(5
^^V ^BOT
,
ATL
L t
m
ft)
i
UNSATURATED
ZONE
r
EAST
1 m
Oft)
\L HIGH WATER TABLE {
"
Figure 3-13. Soil core sampling depths
-------
3.4.1 Compositing Samples
The RCRA Guidance Document: Land Treatment Units (EPA, 1983b) specifies
the number of composited samplesto be collected from background areas and
from the active areas on a hazardous waste land treatment facility. The
information in this document is summarized in Table 3-1, which specifies:
(1) the recommended number of randomly selected samples from background and
active areas, (2) number of samples per composite, (3) total number of
composited samples, (4) sampling depth, and (5) sampling frequency. The soil
samples collected by the techniques described in the previous sections will
be used for the composites.
For some of the sampling tools, such as soil probes and Veihmeyer tubes,
the sample size is generally small enough that the overall size of the
composite is not cumbersome. Other techniques, such as barrel augers, will
provide so much sample that a composite will be of much larger mass than
required for analysis. In this case the sample size should be reduced to a
manageable volume. A simple method is to mix the samples thoroughly by
shovel, divide the mixed soil into quarters, and place a sample from each
quarter into a sample container. Mechanical sample splitters are also
available. EPA (1982b) recommends using the riffle technique. A riffle is a
sample splitting device consisting of a hopper and series of chutes. Mater-
ials poured into the hopper are divided into equal positions by the chutes
which discharge alternately in opposite directions into separate pans
(Soiltest Inc., 1976). A modification of the basic riffle design allows for
quartering of the samples.
3.4.1.1 Compositing with a Mixing Cloth--
Soil scientists often use a large plastic or canvas sheet for composit-
ing samples in the field (Mason, 1982). This method works reasonably well
for dry soils but has the potential for cross contamination problems.
Organic chemicals can create further problems by reacting with the plastic
sheet. Plastic sheeting, however, is inexpensive and can therefore be
discarded after each sampling site.
This method is difficult to describe. It can be visualized if the
reader will think of this page as a plastic sheet. Powder placed in the
center of the sheet can be made to roll over on itself if one corner is
carefully pulled up and toward the diagonally opposite corner. This process
is done from each corner. The plastic sheet acts the same way on the soil as
the paper would on the powder. The soil can be mixed quite well if it is
loose. The method does not work on wet or heavy plastic soils. Clods must
be broken up before attempting to mix the soil.
After the soil is mixed, it is again spread out on the cloth to a
relatively flat pile. The pile is quartered. A small scoop, spoon or
spatula is used to collect small samples from each quarter until the desired
amount of soil is acquired (this usually is about 250 to 500 grams of soil
but can be less if the laboratory desires a smaller sample). This is mixed
and placed in the sample container for shipment to the laboratory. The site
material not used in the sample should be disposed of in a safe manner. This
is especially important where the presence of highly toxic chemicals is
suspected.
36
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3.4.1.2 Compositing with a Mixing Bowl—•
An effective field compositing method has been to use large stainless
steel mixing bowls. These can be obtained from scientific, restaurant, or
hotel supply houses. They can be decontaminated and are able to stand rough
handling in the field. Subsamples are placed in the bowls, broken up, then
mixed using a large stainless steel scoop. The rounded bottom of the mixing
bowl was designed to create a mixing action when the material in it is turned
with the scoop. Careful observance of the soil will indicate the complete-
ness of the mixing.
The soil is spread evenly in the bottom of the bowl after the mixing is
complete. The soil is quartered and a small sample taken from each quarter.-
The subsamples are mixed together to become the sample sent to the labora-
tory. The excess soil is disposed of as waste.
3.5 SAMPLING PROCEDURE
It is assumed that the number and location of sampling sites on the
background area and active portion of the land treatment unit have been
selected in accordance with the random selection procedure described above.
This section describes the following elements of a sampling procedure:
(1) preliminary site preparation, and (2) soil sample collection.
3.5.1 Preliminary Activities
In preparation for sample collection, it is strongly suggested that a
checklist (Table 3-3) be prepared itemizing all of the equipment necessary,
both for sampling and for maintaining quality assurance. Thus all of the
tools needed for sampling should be itemized and located in the transporting
vehicle. Similarly, all of the documentation accessories, such as field
book, maps, labels, etc., should be checked off. A few minutes of prelimin-
ary preparation will ensure that all equipment is on hand and that time will
not be wasted in returning to base for forgotten items.
Careful site preparation will also take a few minutes but is absolutely
necessary to ensure that the samples are representative of in-situ condi-
tions. Specifically, a severe problem with all of the sampling methods
described elsewhere in this chapter is that "contamination" of the sample may
occur by soil falling in the cavity either from the land surface or from the
walls of the borehole. Thus to minimize contamination from surface soils,
loose soils and clods should be thoroughly scraped away from each site prior
to sampling. A shovel or rake will facilitate this operation.
It is recommended that a soil profile description be taken with each
soil core sampling event. The profile description will provide information
on the spatial variable properties important to both land treatment function-
ing and will assist in the interpretation of monitoring results. For
instance, it is quite possible that sandy conduits (e.g., stumpholes or root
channels) may contain different levels of a hazardous constituent than
surrounding soil.
37
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TABLE 3-3. EXAMPLE CHECKLIST OF MATERIALS AND SUPPLIES
10 to 12 Oakfield tube samplers, Model 22-g obtained
from Soil Test, Inc.
Borebrush for cleaning.
10 to 12 ten-quart stainless steel mixing bowls.
A U.S. Army Corps of Engineers tube density sampling
set with 30 to 40 six-inch sample tubes.
Safety equipment as specified by safety officer.
One-quart Mason type canning jars with Teflon liners
(order 1.5 times the number of samples. Excess is for
breakage and contamination losses.).
A large supply of heavy-duty plastic trash bags.
Sample tags.
Chain-of-custody forms.
Site description forms.
Logbook.
Camera with black-and-white film.
Stainless steel spatulas.
Stainless steel scoops.
Stainless steel tablespoons.
Caps for density sampling tubes.
Case of duct tape.
100-foot steel tape.
2 chain surveyor's tape.
Tape measure
Noncontaminating sealant for volatile sample tubes.
Supply of survey stakes.
Compass.
Maps.
Plot Plan.
Trowels.
Shovel.
Sledge Hammer.
Ice chests with locks.
Dry ice.
Communication equipment.
Large supply of small plastic bags for samples.
38
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3.5.2 Sample Collection With Hand-Held Equipment
In the following section, step-by-step sample collection procedures are
described for each of the major soil-sampling devices.
3.5.2.1 Screw-Type Augers—
(1) Locate tip of auger on the soil surface at exact sampling
location.
(2) With the auger and drill stem in an exactly vertical position,
turn and pull down on the handle.
(3) When the auger has reached a depth equivalent to the length of
the auger head, pull the tool out of the cavity.
(4) Gently tap the end of the auger on the ground or on a wooden
board to remove soil from the auger flights. For very wet,
sticky soils it may be necessary to remove the soil using a
spatula or by hand. In the latter instance, the operator is
advised to wear disposable rubber gloves for protection from
organic contaminants.
(5) Clean loose soil away from the auger flights and soil opening.
(6) Insert the auger in the cavity and repeat steps (ii) through
(v). Keep track of the sampling depth using the marks on the
drill rod or by inserting a steel tape in the hole.
(7) When the auger has reached a depth just above the sampling
depth, run the auger in and out of the hole several times to
remove loose material from the sides and bottom of the hole.
(8) Advance the auger into the soil depth to be sampled.
(9) Remove the auger from the cavity and gently place the head on
a clean board or other support. Remove soil from the upper
flight (to minimize contamination). Using a clean spatula or
other tool, scrape off soil from the other flights into the
sample container. Label the sample container pursuant to
information presented in Appendix B.
(10) Pour soil back into the cavity. Periodically use a rod to
tamp the soil to increase the bulk density. Fill the hole to
land surface.
3.5.2.2 Barrel Augers—
The sampling procedures for each of the barrel augers are basically the
same with minor variations. Only the procedure for the post-hole auger is
presented in detail.
(1) Locate auger bit on soil surface at exact sampling location.
39
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(2) With the auger and extension rod in an exactly vertical
position, turn and pull down on the handle (see Figure 3-14).
(3) When the auger has reached a depth equivalent to the length of
the auger head, pull the assembly out of the cavity.
(4) Gently tap the auger head on the ground or on a wooden board
to remove the soil from the auger. For very wet and sticky
soils, it may be necessary to remove the soil using a spatula
or rod or by hand. In the latter instance, the operator is
advised to wear disposable rubber gloves for protection from
organic contaminants.
(5) Remove all loose soil from the interior of the auger and from
the soil opening.
(6) Insert the auger back into the cavity and repeat steps (ii)
through (v). Keep track of the sampling depth using the marks
on the extension rod or by extending a steel tape in the hole.
(7) When the auger has reached a depth just above the sampling
depth, run the auger in and out of the hole several times to
remove loose material.
(8) Advance the auger into the soil depth to be sampled.
(9) Carefully remove the auger from the cavity and gently place
the barrel head on a clean board or other support. Using a
clean spatula or other tool, scrape the soil from the control
part of the head into the sample container. Discard remaining
soil. Label the sample container pursuant to the information
presented in the section entitled "Sampling Protocol".
(10) Pour soil back into the cavity. Periodically use a rod to
tamp the soil to increase the bulk density. Fill hole to land
surface.
3.5.2.3 Tube-Type Samplers: Soil Probe--
The general procedure for soil sampling using soil probes is presented,
together with the modified approach when a "backsaver" attachment is used.
The basic technique is described first.
(1) Place the sampler tip on the soil surface at the exact samp-
ling location.
(2) With the sampling point and extension rod in an exactly
vertical position, push or pull down on the handle to force
the sampler into the soil.
(3) When the auger has reached a depth equivalent to the length of
the sampling tube, twist the handle to shear off the soil.
Pull the tube out of the soil.
40
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Figure 3-14. Barrel auger sampling method (Clements
Associates, Inc., 1983)
-------
(4) Gently remove the soil from the tube using a spatula or rod or
by hand. If the tool is cleaned by hand, the operator should
wear rubber gloves for protection from organic contaminants.
(5) Remove loose soil and soil stuck to the walls of the tool.
Similarly, gently remove loose soil around the soil opening.
(6) Insert the probe back into the cavity and repeat steps (ii)
through (v). Keep track of the sampling depth using the marks
on the rod or by extending a steel tape in the hole. If
necessary, screw on an additional extension rod.
(7) When the auger has reached a depth just above the sampling
depth, run the probe in and out of the hole several times to
remove loose material from the cavity walls.
(8) Advance the auger into the soil depth to be sampled.
(9) Carefully remove the unit from the hole and gently place the
tube on a clean board. Scrape the soil out of the tube or
force the sample out of the tube by pushing down on the top of
the sample. Again, rubber gloves should be used. Using a
clean spatula, gently place soil samples into sample contain-
ers. Label the sample container pursuant to information
presented in the section entitled "Sampling Protocol".
(10) Pour soil back into the cavity, periodically tamping to
increase the bulk density. Fill the hole back to land
surface.
A modified version of the basic sampling procedure for tube samplers
provided with a so-called "back saver" handle is described in Figure 3-15.
3.5.2.4 Tube Type Samplers: Veihmeyer Tubes--
(1) Place the sampler tip on the soil surface at the exact samp-
ling location. Position the tube in an exactly vertical
position.
(2) Place the tapered end of the drive hammer into the tube.
Place one hand around the tube and the other around the hand
grip on the drive hammer. While steadying the tube with one
hand, raise and lower the hammer with the other. Eventually a
depth will be reached where both hands can be used to control
the handle.
(3) Drive the sampler to the desired depth of penetration. For
some soils, the tube may be extremely difficult to remove
because of wall friction. In such a case, the operator may
choose to reduce the depth of penetration during advance of
the hole.
42
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CO
HOW DOES THE BACKSAVEH HANDLE WORK
Procedure used to pull a soil core with a sampling tube equipped with the
"Backsaver Handle" or the "Backsaver N-3 Handle."
(1) Steady the soil probe In a nearly vertical position by grasping the hand-
grip with both hands. Force the sampling tube Into the soil by stepping firm-
ly on the footstep.
(2) Remove the first section of the core by pulling upward on the handgrip.
Empty the sampling tube and clean, (see "cleaning of the soil sampling
tube")
(3) Place the sampling tube In the original hole and push Into the soil until
the footstep Is within an inch or two of the surface of the ground.
(4) While maintaining a slight pressure on the footstep pull upward on the
handgrip, until the footstep has been elevated 6 to 8 inches above the sur-
face of the ground.
(5) Maintain a slight upward pressure on the handgrip and step downward
on the footstep. The footstep now grips the rod and the sampling tube can
be pushed Into the soil until the footstep Is within 1 or 2 Inches above the
ground.
(6) Steps 4 and 5 are repeated until the sampling tube Is full. The depth of
penetration can be determined by the position of the rod end which can be
seen through the viewing holes In the side of the square portion of the
Backsaver Handle. It Is Important not to push the sampling tube Into the
soil to a depth that exceeds the holding capacity of the tube as this jams the
sample and can make removal from the ground extremely difficult.
(7) Remove the full sampling tube by lifting upward on the handgrip. After
the sampling tube has been elevated 6 to 8 Inches, push downward on the
handgrip returning the footstep to within 1 to 2 Inches of the surface of the
ground.
\8) Empty the sampling tube and clean.
(9) Steps 3 through 8 are repeated until the desired depth Is reached.
Procedure used to pull a soil core wtth a sampling tube equipped with the
"Backsaver N-2 Handle."
Same as steps 1 and 2 above.
*ij
Figure 3-15. Operation of "backsaver" handle with soil sampling tube (Clements Associates, Inc., 1983)
-------
(4) Remove the drive hammer from the tool and place the opening in
the hammer above the tube head. Rotate the hammer as required
to allow the slots in the opening to pass through the ears on
the head. Drop the hammer past the ears and rotate the hammer
so that the unslotted opening rests against the ears. Pull
the hammer upward to force the tube out of the ground. (In
some cases it may be necessary to jar the hammer head against
the ears, or have another person pull up on the hammer).
(5) Gently place the side of the tube against a hard surface to
remove soil from the tube. If this procedure does not work,
it may be necessary to insert a long rod inside the tube to
force out the soil.
(6) Scrape off the side of the tube to remove loose soil. Simi-
larly, remove loose soil from the soil cavity.
(7) Insert the tube back into the soil cavity and repeat stops (1)
through (6). Keep track of the sampling depth by the marks on
the tube or by extending a steel tape in the hole.
(8) When the tip has reached a depth just above the sampling
depth, gently run the tube in and out of the hole several
times to remove loose material from the cavity walls.
(9) Drive the tube to the depth required for sampling.
(10) Carefully remove the unit from the hole and gently place the
tip on a clean board. Force the sample out of the tube using
a clean rod or extraction tool. Using a clean spatula, spoon
the soil sample into a sample container. As a matter of
precaution, the uppermost one or two inches of soil should be
discarded on the chance that this segment has been contamina-
ted by soil originating from above the sampling depth. Label
the sample container pursuant to information presented in
Appendix B.
(11) Pore soil back into the cavity, periodically tamping to
increase the bulk density. Fill the hole back to ground
surface.
Since the augers, probes and tubes must pass through contaminated
surface soils before reaching the sampling depth (1.5 m (5 ft)) cross contam-
ination is a real possibility. Soil is compacted into the threads of the
auger and must be extracted with a stainless steel spatula. Probes and tubes
are difficult to decontaminate without long bore brushes and some kind of
washing facility. One possible way to minimize the cross contamination is to
use the auger, probe, or tube to open up a bore hole to the desired depth,
clean the bore hole out by repeatedly inserting the auger, probe or tube and
finally using a separate, decontaminated auger, probe or tube to take a soil
sample through the existing open bore hole.
44
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3.5.2.5. Thin-Walled Tube Samplers--
Generally, in cohesive soils thin-walled samplers are placed into
previously excavated cavities, which are augered or dug out to a location
just above the sampling depth. These thin-walled samplers have been called
Shelby tubes, "Z" tubes, UD tubes (undrsturbed), etc. and are customarily
used with a hollow stem flight auger. The use of a truck mounted hollow stem
auger and a thin-walled sampler, although more difficult to decontaminate,
reduces the chance of serious cross contamination in the samplers and, there-
fore, is the recommended soil sampling technique at hazardous waste land
treatment units.
The procedure to follow for extracting a sample includes:
(1) Using a hollow stem auger to drill down to the 1.5 m (5 ft)
depth
(2) Detach the head assembly from the auger
(3) With the Shelby tube attached to the head assembly and drive
rod, pass the tube down through the hollow stem and into the
soil to the required depth (15 cm (6 in)), using the hoist and
weight assembly.
(4) Pull the tube sampler out of the soil using the hoist
assembly.
(5) Unscrew the tube from the head assembly and place the unit in
a core sample extruder (see Figure 3-16). The plunger should
be placed in the end of the tube with the cutting tip. If
there is no need to examine the sample in the field or if
volatile organics are of concern, the sampler can be capped at
each end with teflon plugs or some type of sealant and sent to
the laboratory.
(6) Gently begin to extrude the sample. Remove and discard the
first 2 to 3 inches of the sample.
(7) Extrude the remaining sample into a sample container. Label
the sample container.
(8) Pour soil back into the soil cavity, periodically tamping to
increase the bulk density. Fill the hole to ground surface.
3.5.2.6 Split Spoon Sampler—
The split spoon sampler is a thick-walled tube 45.7 cm (18 in) or 61 cm
(24 in) long which can be split in half longitudinally and is held together
on each end by a threaded nozzle cutting edge and a threaded head assembly.
The split spoon is used in cohensionless soils or where the structured
properties of the soil need to be known.
45
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.SAMPLE
HYDRAULIC CYLINDER
109 cm
Figure 3-16. Core sample extruding device
-------
A 15.2 cm (6 in) auger is used to drill down to 1.5 m (5 ft). The split
spoon is then driven to its sampling depth (15 cm, (6 in)) through the bottom
of the augered hole and the core extracted.
In most applications a 63.5 kg (140 Ib) hammer is used to drive the
split spoon. The hammer is allowed to free fall 76 cm (30 in) for each blow
to the spoon. The number of blows required to drive the spoon 15.2 cm (6 in)
is counted and recorded. The blow counts are a direct reflection of the
density of the soil and can be used to obtain some information on the soil
structure below surface. Unless this density information is needed for
interpretive purposes, it may not be necessary to record the blow counts. In
soft soils the split spoon can often be forced into the ground by the hydrau-
lic drawdown on the drill rig. This is faster than the hammer method and
does not require the record keeping necessary to record the blowcounts. Most
commercial drilling companies have the equipment and the experience required
to conduct this type of sampling with some supervision from the field
scientist.
There are several variations for split spoon sampling. Samples collec-
ted from soils below the water table or in very soft soils may require the
use of split spoons equipped with retainers in the end of the spoon. The
retainer is made with flexible fingers that close over the end of the tube as
the spoon is retracted from the soil.
Samples collected for the analysis of volatile organic chemicals pose a
problem to the environmental scientist. The volatile chemicals can be lost
during transport and handling. The option that may offer a solution to this
problem is the use of brass, stainless steel or Teflon liners in the split
spoon. Brass liners are available from most engineering and agricultural
supply houses. The liners are easily removed when the split spoon is opened.
The liner tube can be sealed with Teflon plugs and some form of sealant
applied over the plug. This system avoids the problems of the loss of
chemicals that volatilize into the headspace of the sample jars. The liners
can be discarded after analysis if necessary thus reducing the labor costs
required to clean the tubes.
3.5.2.7 Peat Sampler—
(1) Place the sampler tip on the soil surface at the exact samp-
ling location.
(2) With the tube in an exactly vertical position, force the
sampler into the soil to the desired depth of sampling.
(Note: during this stop, the internal plunger is held in-
place within the sampling cylinder by a piston attached to the
end of the push rods).
(3) Jerk up on the actuating rod to allow the plunger to move
upward in the cylinder. (The snap catch will prevent the
plunger from moving back downward in cylinder).
(4) Push the assembly downward to force the cylinder into undis-
turbed soil.
47
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(5) Pull the sampler to the land surface.
(6) Extrude the sample into a clean sample container. Label the
container.
(7) Fill in the cavity with soil, tamping to increase the bulk
density of the added soil. Fill the hole to ground surface.
3.5.3 Sample Collection With Power Equipment
3.5.3.1 Operation of Power Drilling Equipment-
Personnel safety is of utmost importance when operating power-driven
sampling equipment. For this reason it is important to select, and if neces-
sary, train a team of at least two individuals for the sampling program. One
member of the team should be assigned full responsibility for operating the
equipment, whereas the other individual is basically a helper. In addition
to the safety factor, a team approach also expedites the sampling process.
For example, the operator is free to operate the equipment while the helper
assists in logging the hole, collecting samples, preparing notes, etc.
Power-driven samplers are generally supplied with a set of operating
instructions describing how to set up and operate the power train. These
instructions should be carefully studied by the operator and the helper
before the unit is operated for the first time. In addition, the operator
and assistant should be given a demonstration and hands-on training by
someone skilled in operating the equipment. The manufacturer's represen-
tative or sales personnel should be willing to provide this service.
Other elements of safety include requiring that the team members wear
hard hats, gloves, and safety glasses. Depending upon the types of wastes
disposed of at the land treatment sites, other precautions may be required,
such as having oxygen masks available. Clothing should be snug fitting, and
long-sleeved shirts and long pants should be worn. Work boots with steel toes
are recommended. Maintaining an uncluttered work area is also recommended to
minimize all possibility of the operator or assistant stumbling into moving
parts of the rig.
3.5.3.2 Sampling—
As discussed elsewhere in this section, the most common drilling techni-
ques for power sampling are flight augers and drive samplers. Step-by-step
procedures for sampling with these tools are identical to those previously
presented for their hand-held counterparts, including: (1) preliminary
preparation of site, (2) vertical alignment of the tool in the hole, (3) dis-
carding soil from non-sampling horizons, (4) measuring depth of the hole,
(5) collecting a soil sample from the tool, and (6) back-filling the hole
with soil to prevent vertical leakage of pollutants from the treatment zone.
48
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3.5.3.3 Miscellaneous Tools—
Hand tools such as shovels, trowels, spatulas, scoops and pry bars are
helpful for handling a number of the sampling situations. Many of these can
be obtained in stainless steel for use in sampling hazardous pollutants. A
set of tools should be available for each sampling site where cross contamin-
ation is a potential problem. These tool sets can be decontaminated on some
type of schedule in order to avoid having to purchase an excessive number of
these items.
A hammer, screwdriver and wire brushes are helpful when working with the
split spoon samplers. The threads on the connectors often get jammed because
of soil in them. This soil can be removed with the wire brush. Pipe wren-
ches are also a necessity as is a pipe vise or a plumbers vise.
3.6 DECONTAMINATION
One of the major difficulties with soil sampling arises in the area of
cross contamination of samples. The most reliable methods are those that
completely isolate one sample from the next. Freshly cleaned or disposable
sampling tools, mixing bowls, sample containers, etc. are the only way to
insure the integrity of the data.
Field decontamination is quite difficult to carry out, but it can be
done. Hazardous chemical sampling adds another layer of aggravation to the
decontamination procedures. The washing solutions must be collected for
disposal at a waste disposal site.
3.6.1 Laboratory Cleanup of Sample Containers
One of the best containers for soil is the glass canning jar fitted with
Teflon or aluminum foil liners placed between the lid and the top of the jar.
These items are cleaned in the laboratory prior to taking them into the
field. All containers, liners and small tools should be washed with an
appropriate laboratory detergent, rinsed in tap water, rinsed in distilled
water and dried in an oven. They are then rinsed in spectrographic grade
solvents if the containers are to be used for organic chemical analysis.
Those containers used for volatile organics analysis must be baked in a
convection oven at 105°C in order to drive off the rinse solvents.
The Teflon or aluminum foil used for the lid liners is treated in the
same fashion as the jars. These liners must not be backed with paper or
adhesive.
3.6.2 Field Decontamination
Sample collection tools are cleaned according to the following procedure
(Mason, 1982).
• Washed and scrubbed with tap water using a pressure hose or
pressurized stainless steel, fruit tree sprayer.
• Check for adhered organics with a clean laboratory tissue.
49
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• If organics are present, rinse with the waste solvents from
below. Discard contaminated solvent by pouring into a waste
container for later disposal.
t Air dry the equipment.
• Double rinse with deionized, distilled water.
• Where organic pollutants are of concern, rinse with spectro-
graphic grade acetone saving the solvent for use in step 3
above.
• Rinse twice in spectrographic grade methylene chloride or
hexane, saving the solvent for use in step 3.
• Air dry the equipment.
t Package in plastic bags and/or pre-cleaned aluminum foil.
The distilled water and solvents are flowed over the surfaces of all the
tools, bowls, etc. The solvent should be collected in some container for
disposal. One technique that has proven to be quite effective is to use a
large glass or stainless steel funnel as the collector below the tools during
flushing. The waste then flows into liter bottles for later disposal (use
the empty solvent bottles for this). A mixing bowl can be used as a collec-
tion vessel. It is then the last item cleaned in the sequence of operations.
The solvents used are not readily available. Planning is necessary to
insure an adequate supply. The waste rinse solvent can be used to remove
organics stuck to the tools. The acetone is used as a drying agent prior to
use of the methylene chloride or hexane.
Steam cleaning might prove to be useful in some cases but extreme care
must be taken to insure public and worker safety by collecting the wastes.
Steam alone will not provide assurance of decontamination. The solvents will
still have to be used.
3.7 SAFETY PRECAUTIONS
Safety problems may arise when operating power equipment and when
obtaining soil cores at sites used to dispose of particularly toxic or
combustible wastes.
The problem of operator contact with hazardous wastes and the possibil-
ity of fires and explosions are not factors of concern when soil-sampling at
background sites. However, these items may be of very real concern when
sampling active areas. EPA (1983a) review elements of personnel health
safety at land treatment areas from the viewpoint of the disposal operators.
However, many of these concerns also apply to workers obtaining soil-core
samples during a monitoring program. For example, many wastes emit toxic
vapors even following land disposal (EPA, 1983a). Such vapors may cause
short or prolonged illness in unprotected workers. Long-term direct contact
with wastes (e.g., during handling of soil samples) may be considered to be a
carcinogenic risk.
50
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Explosive gases may be given off from land treatment areas used to
dispose of combustible wastes (EPA, 1983a). For such wastes, extreme caution
must be taken when sampling to avoid creating sparks or the presence of open
flames. Sparks will be of particular concern when sampling with power-driven
equipment. Workers should not be permitted to smoke.
Protective clothing that should be worn during sample collection must be
decided on a case-by-case basis. As a guide, the alternative levels of
protective equipment recommended by Zirshky and Harris (1982) for use during
remedial actions at hazardous waste sites could be employed at land treatment
sites used to dispose of highly toxic wastes. Specific items for each level
are itemized in Table 3-4. Level 1 equipment is recommended for workers
coming into contact with extremely toxic wastes. Such equipment items offer
the maximum in protection. Level 2 equipment can be used by supervising
personnel who do not directly contact the waste. Level 3 equipment applies
primarily to sampling on background areas or on treatment sites used to
dispose of fairly innocuous wastes. Level 4 equipment could be used during
an emergency situation such as a fire.
OSHA is the principal Federal agency responsible for worker safety.
This agency should be contacted for information on safety training procedures
and operational safety standards (EPA, 1983a).
3.8 DATA ANALYSIS AND EVALUATION
A critical step in any monitoring program is the proper analysis and
evaluation of the data collected. Input from the field scientist is important
in this data interpretation. The field scientist should have made observations
of field conditions (e.g., weather, unusual waste distribution patterns, soil
conditions, etc.) when the samples were taken and noted these in the field log
book (see Appendix B). This information will assist in explaining the sampling
data and provide insight into potential remedial actions that may be taken in
the event they are necessary.
Appendix C provides example sheets for summarizing the analytical and
statistical analysis results from unsaturated zone monitoring. Summary sheets,
such as these, and the chain of custody documentation described in Appendix B,
should be included in the operating record of the facility.
The land treatment regulations (see 40 CFR Part 264) require that the
owner or operator determine if hazardous constituents have migrated below the
treatment zone at levels that are statistically increased over background
levels. The following analysis can be used to make this determination. This
analysis can be done on a calculator.
The mean (Eq. 3-1), variance (Eq. 3-2), and a two-sided (100(l-a}%) confi-
dence interval (Eq. 3-3) are first calculated by the following equations:
y = z y./n (3-1)
1-1 1
51
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TABLE 3-4. PERSONNEL PROTECTIVE EQUIPMENT
(Zirshky and Harris, 1982)
Equipment
3-M White Cap with air-line respiration
PVC chemical suit
Chemical gloves taped to suit, leather gloves as needed
Work boots with neoprene overshoes taped to chemical suit
Cotton coveralls, underclothing/socks (washed daily)
Cotton glove liners
Walkie-talkies for communications
Safety glasses or face shield
Hard hat
Air purifying respirator with chemical cartridges
PVC chemical suit and chemical gloves
Work boots with neoprene overshoes taped to chemical suit
Cotton coveralls/underclothing/socks (washed daily)
Cotton glove liners
Walkie-talkies for communications
Safety glasses or face shield
Hard hat
Disposable overalls and boot covers
Lightweight gloves
Safety shoes
Cotton coveralls/underclothing/socks (washed daily)
Safety glasses or face shield
Positive pressure self-contained breathing apparatus
PVC chemical suit
Chemical gloves, leather gloves, as needed
Neoprene safety boots
Cotton coveralls/underclothing/socks (washed daily)
Walkie-talkie for communications
Safety glasses or face shield
52
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n ?
V(y) = E(y, - y) /n(n-l) (3-2)
i=l ]
where yi = ith sample
n = number of samples
y = sample mean
V (y) = estimated variance of the mean
L - y ± ta/2 V(y) (3-3)
where L = 100(l-a)% confidence interval
a/2 = the a/2 percentage value from a
t-distribution with (n-1) degrees of freedom
The data for each hazardous constituent or "principal hazardous consti-
tuent" (if identified in permit) from the background area can be statisti-
cally compared to the data from the appropriate uniform area in the active
portion using the Student's t-test. The t-test given in equation 3-4 below
(Li, 1959) is used to determine if the mean of the hazardous constituents in
the uniform area is greater than that in the appropriate background area.
This equation assumes homogeneity of variances which is most often the case
in soils work.
For testing if the uniform area (active portion) mean is greater than
the background mean (i.e., one-tailed test), compare the calculated t-value
(t ) with the critical value t , where t is the upper tail value from the
t-distribution with n, + n~ - 2 degrees of freedom at the a significance
level. If t > t , there is a statistically significant increase in the
c ot
uniform area (active portion) mean over the background area mean.
tc = (yj - yz) sp (l/nj + l/n2) (3-4)
where t = calculated t-value
y. = mean for area k
k = 1 for uniform area (active portion);
k = 2 for background area
53
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2
s = pooled variance calculated
p by formula Eq. 3-5
n. = number of samples in area k
2 n, p n9 p
5 P = i=i
l 9 9 9
l (y,- - yV2 + z2 (y, - y2) (3-5)
=1 i i j=1 j ^
n, + r\2 - 2
54
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SECTION 4
SOIL-PORE LIQUID MONITORING
The sampling of soil-pore liquid was reported in the literature in the
early 1900's when Briggs and McCall (1904) described a porous ceramic cup
which they termed an "artificial root". The sampling of soil-pore liquid has
received increasing attention in more recent years as concern over migration
of pollutants in soil has increased. As shown in Figure 4-1, different soils
are capable of yielding different levels of water. The unsaturated zone, as
described in Section 2, is the layer of soil between the land surface and the
groundwater table. At saturation the volumetric water content is equivalent
to the soil porosity (see Figure 4-1). In contrast the unsaturated zone is
usually found to have a soil moisture content less than saturation. For
example, the specific retention curve on Figure 4-1 depicts the percentage of
water retained in previously saturated soils of varying texture after gravity
drainage has occurred. Suction-cup lysimeters are used to sample pore
liquids in unsaturated media because pore liquid will not readily enter an
open cavity at pressures less than atmospheric (The Richard's outflow
principle).
Suction-cup lysimeters are made up of a body tube and a porous cup.
When placed in the soil, the pores in these cups become an extension of the
pore space of the soil. Consequently, the water content of the soil and cup
become equilibrated at the existing soil-water pressure. By applying a
vacuum to the interior of the cup such that the pressure is slightly less
inside the cups than in the soil solution, flow occurs into the cup. The
sample is pumped to the surface, permitting laboratory determination of the
quality of the soil solution in situ.
Although a number of techniques are available for indirectly monitoring
the movement of pollutants beneath waste disposal facilities, soil core
sampling and suction-cup lysimeters, remain the principal methods for dir-
ectly sampling pore liquids in unsaturated media. The main disadvantages of
soil core sampling are that it is a destructive technique (i.e., the same
sample location cannot be used again) and it may miss fast-moving constitu-
ents. Lysimeters have been used for many years by agriculturists for moni-
toring the flux of solutes beneath irrigated fields (Biggar and Nielsen,
1976). Similarly, they have been used to detect the deep movement of pollu-
tants beneath land treatment units (Parizek and Lane, 1970). Inasmuch as
lysimeters are the primary tools for soil pore liquid monitoring at land
treatment units, understanding the basic principles of lysimeter operation
and their limitations is important to owners and operators of such units, as
well as those charged with permitting land treatment units. This section
will discuss soil moisture/tension relationships, soil pore-liquid sampling
equipment, site selection, sampling frequency and depths, installation and
operation of the available devices, and sample collection, preservation,
storage, and shipping.
55
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45
40
35-
*™
D 30-
5 25-
3 15-
POROSITY
SPECIFIC RETENTION
CO
CO
UJ
I
3
3
UJ
SCO
3
z§
o
Figure 4-1. Variation of porosity, specific yield, and
specific retention with grain size (Scott
and Scalmanini, 1978)
56
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It should be recognized, however, that situations may occur where the
flow velocities in the unsaturated zone are higher than empirically demon-
strated by Darcy's Law. As a result, the wetting front will not be uniform
and most of the flow will occur through macropores. This type of gravity
flow in highly structured soils will not be sampled effectively by suction
lysimeters. The most promising technique for sampling soil pore-liquid in
highly structured soils is pan lysimeters (e.g., free drainage glass block
samplers). This kind of sampling probably will have its most utility in the
treatment demonstration phase of a permit application because structured
soils that permit gravity flow may not have sufficient treatment capabilities
to satisfy the treatment demonstration. If the treatment demonstration is
successfully completed, pan lysimeters may be an important element in the
soil pore-liquid monitoring program for the full-scale facility.
4.1 SOIL MOISTURE/TENSION RELATIONSHIPS
Unlike water in a bucket, free, unlimited access to water does not exist
in the soil. Soil water or, as it is frequently called, "soil moisture", is
stored in the small "capillary" spaces between the soil particles and on the
surfaces of the soil particles. The water is attracted to the soil parti-
cles, and tends to adhere to the soil. The smaller the capillary spaces
between the particles, the greater the sticking force. For this reason, it
is harder to get moisture out of fine clay soils than it is from the larger
pores in sandy soils, even if the percent of moisture in the soil, by weight,
is the same.
Figure 4-2 shows the results of careful research work done with special
extractors. As described by the Soilmoisture Equipment Corporation (1983),
the graph shows the relationship of the percent of moisture in a soil to the
pressure required to remove the moisture from the soil. These are called
Moisture Retention Curves. The pressure is measured in bars* which is a unit
of pressure in the metric system. Figure 4-2 clearly points out that two
factors are involved in determining ease of water sampling: 1) moisture
content, and 2) soil type.
Moisture in unsaturated soil is always held at suctions or pressures
below atmospheric pressure. To remove the moisture, one must be able to
develop a negative pressure or vacuum to pull the moisture away from around
the soil particles. For this reason we speak of "Soil Suction". In wet
soils the soil suction is low, and the soil moisture can be removed rather
easily. In dry soils the Soil Suction is high, and it is difficult to remove
the soil moisture.
Given two soils (one clay and one sand) with identical moisture con-
tents, it will be more difficult to extract water from the finer soil (clay)
because water is held more strongly in very small capillary spaces in clays.
fi 7
*By definition a bar is a unit of pressure equal to 10 dyne/cm . It is
equivalent to 100 kPa (Kilopascals), or 14.5 psi, or approximately 1 atmos-
phere, or 750 mm of mercury, or 29.6 inches of mercury, or 1,020 cm of water,
or 33.5 feet of water.
57
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50r
CHINO SILTY CLAY
PACHAPPA FINE SANDY LOAM
HANFORD SAND
SOIL SUCTION, BARS
Figure 4-2. Moisture retention curves - three soil types
(Soilmoisture Equipment Corp., 1983)
58
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Another fact, brought out by the graphs on Figure 4-2, is that silty
clay soil with 30 percent moisture, if placed in contact with a sandy soil
with only 10 percent moisture will actually suck moisture out of the sandy
soil until the moisture content in the sandy soil is only 5 percent. This is
due to the greater soil tension in the fine clay texture.
4.2 PORE-LIQUID SAMPLING EQUIPMENT
Well and open cavities cannot be used to collect solution flowing in the
unsaturated zone under suction (negative pressures). The sampling devices
for such unsaturated media are thus called suction samplers or lysimeters.
Everett et al. (1983) provides an in depth evaluation of the majority of
unsaturated zone monitoring equipment. Law Engineering and Testing Company
(1982) provides a description of some of the available suction lysimeters
(Appendix D). Three types of suction lysimeters are (1) ceramic-type sam-
plers, (2) hollow fiber samplers, and (3) membrane filter samplers.
Because of the potential for macropore flow, pan lysimetry should be
employed for soil-pore liquid monitoring in addition to suction lysimetry
during the treatment demonstration. While pan lysimeters (e.g., glass block
samplers) are not at present commercially available, they are relatively easy
to construct and instrument (R.R. Parizek, personal communication, 1984).
However, installation will require more skill and effort than suction lysi-
meters (K. Shaffer, personal communication, 1984).
4.2.1 Ceramic-Type Samplers
Two types of samplers are constructed from ceramic material: the
suction cup and the filter candle. Both operate in the same manner. Basic-
ally, ceramic-type samplers comprise the same type of ceramic cups used in
tensiometers. When placed in the soil, the pores in these cups become an
extension of the pore space of the soil. Although cups have limitations, at
the present time they appear to be the best tool available for sampling
unsaturated media, particularly in the field. The use of teflon for the body
tube parts and the porous segment (instead of a porous ceramic) may reduce
the chemical interaction between the sampler and the hazardous waste.
Suction cups may be subdivided into three categories: (1) vacuum
operated soil-water samplers, (2) vacuum-pressure samplers, and (3) vacuum-
pressure samplers with check valves. Soil-water samplers generally consist
of a ceramic cup mounted on the end of a small-diameter PVC tube, similar to
a tensiometer (see Figure 4-3). The upper end of the PVC tubing projects
above the soil surface. A rubber stopper and outlet tubing are inserted into
the upper end. Vacuum is applied to the system and soil water moves into the
cup. To extract a sample, a small-diameter tube is inserted within the
outlet tubing and extended to the base of the cup. The small-diameter tubing
is connected to a sample-collection flask. A vacuum is applied via a hand
vacuum-pressure pump and the sample is sucked into the collection flask.
These units are generally used to sample to depths up to 6 feet from the land
surface. Consequently, they are used primarily to monitor the near-surface
movement of pollutants from land disposal facilities or from irrigation
return flow.
59
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PLASTIC TUBE
WATER
SAMPLED
VACUUM TEST HAND PUMP
VACUUM
COLLECTED SOIL-WATER SAMPLE
Figure 4-3. Soil-water sampler (courtesy, Soilmoisture
Equipment Corp., 1978)
60
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To extract samples from depths greater than the suction lift of water
(about 25 feet), a second type of unit is available, the so-called vacuum-
pressure lysimeter. These units were developed by Parizek and Lane (1970)
for sampling the deep movement of pollutants from a land disposal project in
Pennsylvania. The design of the Parizek and Lane sampler is shown in Figure
4-4. The body tube of the unit is about 2 feet long, holding about 1 liter
of sample. Two copper lines are forced through a two-hole rubber stopper
sealed into a body tube. One copper line extends to the base of the ceramic
cup as shown and the other terminates a short distance below the rubber
stopper. The longer line connects to a sample bottle and the shorter line*
connects to a vacuum-pressure pump. All lines and connections are sealed.
In operation, a vacuum is applied to the system (the longer tube to the
sample bottle is clamped shut at this time). When sufficient time has been
allowed for the unit to fill with solution, the vacuum is released and the
clamp on the outlet line is opened. Air pressure is then applied to the
system, forcing the sample into the collection flask. A basic problem with
this unit is that when air pressure is applied, some of the solution in the
cup may be forced back through the cup into the surrounding pore-water
system. Consequently, this type of pressure-vacuum system is recommended for
depths only up to about 50 feet below land surface. In addition to the
monitoring effort of Parizek and Lane, these units were used by Apgar and
Langmuir (1971) to sample leachate movement in the vadose zone underlying a
sanitary landfill.
Morrison and Tsai (1981) proposed a modified lysimeter design with the
porous material located midway up the sampling chamber instead of at the
bottom (see Figure 4-5, Morrison and Tsai, 1981). This mitigated the basic
problem of sample solution being forced back through the cup when air press-
ure is applied. Polyethylene with 2.5-micron pores has been substituted for
ceramic porous material to provide greater sampler durability and comparable
or reduced ion attenuation potential.
Wood (1973) reported on a modified version of the design of Parizek and
Lane. Wood's design is the third suction sampler discussed in this subsec-
tion. Wood's design overcomes the main problem of the simple pressure-vacuum
system; namely, that solution is forced out of the cup during application of
pressure. A sketch of the sampler is shown in Figure 4-6. The cup ensemble
is divided into lower and upper chambers. The two chambers are isolated
except for a connecting tube with a check valve. A sample delivery tube
extends from the base of the upper chamber to the surface. This, tube also
contains a check valve. A second shorter tube terminating at the top of the
sampler is used to deliver vacuum or pressure. In operation, when a vacuum
is applied to the system, it extends to the cup through the open one-way
check valve. The second check valve in the delivery tube is shut. The
sample is delivered into the upper chamber, which is about 1 liter (0.26
gallon) in capacity. To deliver the sample to the surface, the vacuum is
released and pressure (generally of nitrogen gas) is applied to the shorter
tube. The one-way valve to the cup is shut and the one-way valve in the
delivery tube is opened. Sample is then forced to the surface. High press-
ures can be applied with this unit without danger of damaging the cup.
Consequently, this sampler can be used to depths of about 150 feet below land
surface (Soilmoisture Equipment Corporation, 1978). Wood and Signer (1975)
used this sampler to examine geochemical changes in water during flow in the
vadose zone underlying recharge basins in Texas.
61
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,2-WAY PUMP
PLASTIC TUBE
AND CLAMP
VACUUM PORT
AND GAUGE
PLASTIC TUBE
AND CLAMP
TAPE
PRESSURE „
VACUUM IN
8ENTCNITE-
a/I6HNCH
COPPER TUBE
PLASTIC PIPE
24 INCHES LONG
6-INCH HOLE
WITH TAMPED
SlUCA SAND
' BACKFILL
POROUS CUP
BENTONITE
\>^
f^rf SAMPLE BOTTLE
/IPs
-DISCHARGE TUBE
Figure 4-4. Vacuum-pressure sampler (Parizek and
Lane, 1970)
62
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PRESSURE/VACUUM INLET-
2-incfc 0.0. PVC TUBE •
COLLECTION CHAMBER-
THREADED COUPLING-
•EXTRACTION OUTLET
-THREADED COUPLING
•RIGID 1/4-inch I.D. PVC TUBE
.2.5 MICRON POLYETHYLENE
POROUS METERIAL
PVC WELL POINT
Figure 4-5. Modified pressure-vacuum lysimeter
(Morrison and Tsai, 1981).
63
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VACUUM-AIR PRESSURE LINE
UPPER CHECK VALVE
MPLS DISCHARGE LINE
UPPER CHAMBER
LOWER CHECK VALVE
TUBING
LOWER CHAMBER
T10N CUP
Figure 4-6. "Hi/pressure-vacuum soil-water sampler" (courtesy
Soilmoisture Equipment Corp., 1978)
64
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A sampling unit employing a filter candle is described by Duke and Haise
(1973). The unit, described as a "vacuum extractor," is installed below
plant roots. Figure 4-7 shows an illustrative installation. The unit
consists of a galvanized sheet metal trough open at the top. A porous
ceramic candle (12 inches long and 1.27 inches in diameter) is placed into
the base of the trough. A plastic pipe sealed into one end of the candle is
connected to a sample bottle located in a nearby manhole or trench. A
small-diameter tube attached to the other end of the candle is used to rewet
the candle as necessary. The trough is filled with soil and placed within a
horizontal cavity of the same dimensions as the trough. The trough and
enclosed filter candle are pressed up against the soil via an air pillow or
mechanical jack. In operation, vacuum is applied to the system to induce
soil-water flow into the trough and candle at the same rate as in the sur-
rounding soil. The amount of vacuum is determined from tensiometers.
Hoffman et al. (1978) used this type of sampler to collect samples of irriga-
tion water leaching beneath the roots of orange trees during return flow
studies at Tacna, Arizona.
4.2.2 Cellulose-Acetate Hollow Fiber Samplers
Jackson, Brinkley, and Bondietti (1976) described a suction sampler
constructed of cellulose-acetate hollow fibers. These semi permeable fibers
have been used for dialysis of aqueous solutions, functioning as molecular
sieves. Soil column studies using a bundle of fibers to extract soil solu-
tion showed that the fibers were sufficiently permeable to permit rapid
extraction of solution for analysis. Soil solution was extracted at soil-
water contents ranging from 50 to 20 percent.
Levin and Jackson (1977) compare ceramic cup samplers and hollow fiber
samplers for collecting soil solution samples from intact soil cores. Their
conclusion is: "... porous cup lysimeters and hollow fibers are viable
extraction devices for obtaining soil solution samples for determining EC,
Ca, Mg, and PO.-P. Their suitability for N03-N is questionable." They also
conclude that nollow fiber samplers are more suited to laboratory studies,
where ceramic samplers are more useful for field sampling.
4.2.3 Membrane Filter Samplers
Stevenson (1978) presents the design of a suction sampler using a
membrane filter and a glass fiber prefilter mounted in a "Swinnex" type
filter holder. Figure 4-8 shows the construction of the unit. The membrane
filters are composed of polycarbonate or cellulose-acetate. The "Swinnex"
filter holders are manufactured by the Millipore Corporation for filtration
of fluids delivered by syringe. A flexible tube is attached to the filter
holder to permit applying a vacuum to the system and for delivering the
sample to a bottle.
The sampler is placed in a hole dug to a selected depth. Sheets of
glass fiber "collectors" are placed in the bottom of the hole. Next, two or
three smaller glass fiber "wick" discs that fit within the filter holder are
placed in the hole. Subsequently, the filter holder is placed in the hole
with the glass fiber prefilter in the holder contacting the "wick" discs.
The hole is then backfilled.
65
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CROSS SECTION
A—A
ADJUSTABLE
VACUUM
SOLUTION
DUAL CHAMB
TRICKLE TUBING
FILTER CANDLE-7
AIR PILLOW
UNDISTURBED
SOIL
DISTURBED
SOIL
SAMPUN6
BOTTLE
SHEET METAl;
TROUGH
— *=*
Figure 4-7. Facilities for sampling irrigation return flow
via filter candles, for research project at
Tacna, Arizona (Hoffman et al., 1978)
66
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SOIL
SAMPLING TUBE
FILTER SUPPORT/BASE
"SWINNEX"
FILTER HOLDER
MEMBRANE FILTER
LASS FIBER PREF1LTER
iLASS FIBER "WICX"
;:-*-^3LASs
FIBER
•:': COLLECTOR
SOIL
Figure 4-8. Membrane filter sampler (Stevenson, 1978)
67
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In operation, soil water is drawn into the collector system by capillar-
ity. Subsequently, water flows in the collector sheets toward the glass
fiber wicks as a result of the suction applied to the filter holder
assembly. The glass fiber prefilter minimizes clogging of the membrane
filter by fine material in the soil solution.
During field tests with the sampler, it was observed that sampling rates
decreased with decreasing soil-water content. The "wick and collector"
system provided contact with a relatively large area of the soil and a
favorable sampling rate was maintained even when the "collector" became
blocked with fine soil. The basic sampling unit can be used to depths of 4
meters.
4.2.4 Pan Lysimeters
The likelihood that bypass of a suction lysimeter will occur should be
demonstrated during the treatment demonstration phase for land treatment
units located in highly structured soils. It is important to acknowledge the
occurrence of macropore flow under certain soil conditions and its signifi-
cant potential to contaminate groundwater. The most appropriate device for
sampling macropore flow is the pan-type lysimeter. The suction lysimeter is
unable to effectively sample macropore flow.
There are a number of designs for pan-type lysimeters. Parizek and Lane
(1970) constructed a 12x15 inch pan lysimeter (Figure 4-9) from 16 gauge sheet
metal. Barbee (1983) employed a perforated 12x12 inch glass brick, the kind
used in masonry construction, as a pan lysimeter (Figure 4-10). Shaffer et al.
(1979) devised a 20 cm diameter pan lysimeter with a tension plate capable of
pulling 6 centibars of tension. A pan lysimeter can be constructed of any
non-porous material provided a leachate-pan interaction will not jeopardize the
validity of the monitoring objectives. The pan itself may be thought of as a
shallow draft funnel. Water draining freely through the macropores will
collect in the soil just above the pan cavity. When the tension in the
collecting water reaches zero, dripping will initiate and the pan will funnel
the leachate into a sampling bottle. The use of a tension plate or a fine sand
packing reduces the extent of capillary perching at the cavity face and
promotes free water flow into the pan.
4.3 CRITERIA FOR SELECTING SOIL-PORE LIQUID SAMPLERS
In selecting soil-pore liquid sampling equipment, the following criteria
should be considered: cost, commercial availability, installation require-
ments, hazardous waste interaction, vacuum requirements, soil moisture
content, soil characteristics and moisture regimes, durability, sample
volume, and sampling depth. Fritted glass samplers, for example, are too
fragile for field application. Plastic lysimeters require a continuous
vacuum and high soil moisture levels. The vacuum extractor
requires intensive installation procedures and a continuous
"Swinnex" sampler has difficult installation procedures and
small a sample. Some samplers, such as the aluminum oxide porous cup sam-
pler, are not commercially available. All teflon samplers are more expensive
than PVC body parts and ceramic cups. The high pressure-vacuum samplers are
not required for the shallow sampling depths at land treatment units. The
is expensive,
vacuum. The
produces too
68
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-12 in-
SIDE VIEW
COPPER
TUBING
-15in
PLAN VIEW
GALVANIZED
16-GAGE
METAL PANS
Figure 4-9. Example of a pan lysimeter
69
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Figure 4-10. Free drainage glass block sampler
-------
simple vacuum lysimeter cannot be used in situ with the sampler totally
covered by soil.
In most cases, the lysimeters of choice at land treatment units will be
pressure-vacuum ceramic or teflon lysimeters. Both the ceramic and teflon
models have certain limitations, which are currently being evaluated in an
EPA research project. Most pressure-vacuum lysimeters are reasonably priced,
commercially available, and easy to install. In addition, a constant vacuum
apparatus is not required. They can be used in situ at depths well within
the requirements of land treatment units and can produce a large sample
volume. Body tubes of various lengths are available to compliment the volume
and sample depth requirements.
Macropore flow may be of concern depending upon the soil structure. In
this case, pan lysimeters samplers are able to most efficiently sample a
pulsed element input (i.e., large rainfall event) to saturated flow; whereas,
the suction sampler samples saturated flow less efficiently and non-saturated
flow more efficiently. These results agree with other studies which have
shown that pan lysimeters can only sample and thus monitor the movement of
gravitational water when precipitation is equal to or greater than field
capacity requirements or when there is a large water input into the soil
(Parizek and Lane, 1970; Tadros and McGarity, 1976; Fenn et al., 1977).
However, in the unsaturated zone of soils, most water movement is in the wet
moisture range (0 to -50 kPa soil moisture tensions, Reeve and Doering,
1965), and in well structured soils through macropores (Shaffer et al.,
1979), which accounts for the vast majority of the water and chemical consti-
tuents that can be lost from the soil by leaching. Thus, a free drainage
sampler could have the following advantages over the porous suction cup
design:
1) It is a continuously sampling "collection" system without the
need for continuous vacuum, thus reducing its cost of
operation.
2) Because vacuum is not needed to extract a soil solution sample
from the soil, there is less potential for losing volatile
compounds in the sample obtained.
3) Its large surface area may enhance sample representativeness,
particularly in well structured soils.
4) The method of installation allows monitoring the natural
percolation of liquids through the unsaturated zone without
alteration of flow.
5) If made of chemically inert materials (i.e., glass), it has
less potential for altering the chemical composition of a
sample obtained by it.
4.3.1 Preparation of the Samplers
A decision must be made on the size of pressure-vacuum lysimeters to be
installed at the site, and the composition of the pressure-vacuum tubing.
According to data by Silkworth and Grigal (1981), the larger commercially
71
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available units with a 4.8 cm diameter are more reliable than the 2.2 cm
diameter units, influence water quality less, and yield a larger volume of
sample for analysis. Although various materials have been used for conduct-
ing tubing (e.g., polypropylene and copper tubing), it is advisable to select
teflon tubing to minimize contamination and interference with the sample.
In order to avoid interferences from chemical substances attached to
porous sampling points, it is recommended advisable to prepare each unit
using the following procedure described by Wood (1973). Clean the cups by
letting approximately 1 liter of 8N Hcl seep through them, and rinse thor-
oughly by allowing 15 to 20 liters of distilled water to seep through. The
cups are adequately rinsed when there is less than a 2 percent difference
between the specific conductance of the distilled water input and the output
from the cup.
4.4 RANDOM PORE-LIQUID MONITORING SITE SELECTION
The RCRA Guidance Document: Land Treatment Units (EPA, 1983b) includes
recommendations on the numbers and locations of pore-liquid samplers for both
background and active portions, as well as the specifications for sampling
frequency. These specifications are summarized on Table 4-1.
The RCRA guidance document suggests that the pore-liquid monitoring
sites be randomly selected. In practice, each site is selected separately,
randomly, and independently of any sites previously drawn. For pore-liquid
monitoring, each site to be included in the "sample" is a volume of liquid
(soil-pore liquid).
The field location for soil-pore liquid devices is obtained by selecting
random distances on a coordinate system and using the intersection of the two
random distances on a coordinate system as the location at which a soil-pore
liquid monitoring device should be installed.
The location, within a given uniform area of a land treatment unit
(i.e., active portion monitoring), at which a soil-pore liquid monitoring
device should be installed is determined using the following procedure (EPA,
1983b):
(1) Divide the land treatment unit into uniform areas (see Figure
3-12). A qualified soil scientist should be consulted in
completing this step.
(2) Map each uniform area by establishing two base lines at right
angles to each other which intersect at an arbitrarily selec-
ted origin, for example, the southwest corner. Each baseline
should extend to the boundary of the uniform area.
(3) Establish a scale interval along each base line. The units of
this scale may be feet, yards, miles, or other units depending
on the size of the uniform area. Both base lines must have
the same scale.
72
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TABLE 4-1. SUMMARY OF GUIDANCE ON PORE-LIQUID SAMPLING
Location of Sampling
Location Number of Units Portion of Unit Frequency
Background 2 each on similar With 12 inch depth Quarterly or
soils found on below treatment zone whenever
treatment area liquid is
present
Active a. Uniform area With 12 inch depth Quarterly or
less than 12 acres; below treatment zone within 24
6 units hours of
b. Uniform area significant
greater than 12 waste appli-
acres: 2 per 4 acres cation
73
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(4) Draw two random numbers from a random numbers table (usually
available in any basic statistics book, see Appendix A). Use
these numbers to locate one point along each of the base
lines.
(5) Locate the intersection of two lines drawn perpendicular to
these two base line points. This intersection represents one
randomly selected location for installation of one soil-pore
liquid device. If this location at the intersection is
outside the uniform area or is within 10 m of another loca-
tion, disregard and repeat the above procedure.
(6) For soil-pore liquid monitoring, repeat the above procedure as
many times as necessary to obtain six locations for installa-
tion of a soil-pore liquid monitoring device (location) per
uniform area, but no less than two devices per 1.5 hectares
(4 acres). Monitoring at these same randomly selected loca-
tions will continue throughout the land treatment unit life
(i.e., devices do not have to be relocated at every sampling
event).
(7) If the device must be replaced for some reason, go through the
procedure again to get a new location.
One point should be made regarding randomly locating soil-pore liquid
monitoring devices in the active portion according to the procedure specified
above. In order to prevent operational inconvenience and sampling bias, the
monitoring system should be designed and installed so that the above-ground
portion of the device is located at least 10 meters (30 feet) from the
sampling location. If the above-ground portion of the device is located
immediately above the sampling device, the sampling location will often be
avoided because of operational difficulties. Thus, samples collected at this
location will be biased and not representative of the treated area. The
distance may be shorter than 10 m (30 ft) if the operator can ensure no
sampling bias (i.e., hazardous waste treatment practices above the sampler
will be the same as the rest of the uniform area) due to operational
practices.
Locations for monitoring on background areas should be randomly deter-
mined using the following procedure:
(I) Consult a qualified soil scientist in determining an accept-
able background area. The background area must have charac-
teristics (i.e., at least soil series classification) similar
to those present in the uniform area of the land treatment
unit it is representing.
(2) Map an arbitrarily selected portion of the background area
(preferably the same size as the uniform area) by establishing
two base lines at right angles to each other which intersect
at an arbitrarily selected origin.
(3) Complete steps 3, 4, and 5 as defined above.
74
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(4) For soil-pore liquid monitoring, repeat this procedure as
necessary to obtain two locations for soil-pore liquid moni-
toring devices within each background area.
4.4.1 Surveying in the Locations of Sites and Site Designations
The exact location of each sampler on the active and background areas
should be designated on a detailed map of the treatment area. Subsequently,
a surveying crew should be sent into the field to precisely locate the
coordinates of the sites in reference to a permanent marker. This step is
important to facilitate future recovery of any failed samplers.
For convenience, each sampler location should be given a descriptive
designation to facilitate all future activities at the site. For example, this
designation should be posted at the sampling station (which will be off the
active portion) and should be marked on all collection flasks to facilitate
differentiating between samples. Examples of site designations are shown in
Figure 4-11. The selection of a designation is purely arbitrary and any
convenient or easily recalled symbol could be used.
4.5 SAMPLE NUMBER, SIZE, FREQUENCY AND DEPTHS
Background concentrations of hazardous constituents can be established
using the following procedures.
(1) For each soil series present (see Figure 3-12) in the treat-
ment zone, install two soil-pore liquid monitoring devices at
randomly selected locations in similar soils (Figure 4-12)
where waste has not been applied. The sample collecting
portions of the monitoring devices should be placed at a depth
no greater than 30 centimeters (12 inches) below the actual
treatment zone used at the unit (Figure 4-13).
(2) Collect a sample from each of the soil-pore liquid monitoring
devices on at least a quarterly basis for at least one year.
If liquid is not present at a regularly scheduled sampling
event, a sample should be collected as soon as liquid is
present.
(3) Composite the two quarterly samples (from different devices)
to form one composite sample for analysis each quarter; a
total of four composite samples will be formed over the one
year period.
The active portion of a land treatment unit can be sampled using the
following procedures:
(1) The owner or operator should install six soil-pore liquid
monitoring devices at randomly selected locations per uniform
area, but no less than two devices per 1.5 hectares (4 acres).
A uniform area is an area of the active portion of a land
treatment unit which is composed of soils of the same soil
series and to which similar wastes or waste mixtures are^
applied at similar application rates. The sample collecting
portion of the monitoring device should be placed at a depth
75
-------
CD
'_jjM(j?~''~~miir
fe^^z^^zizs^z^s^^^iz^^z-zz^z^is:
NEC-1
SAMPLING
STATION
SWC-'l
SAMPLWG
SJAJ\ON
EM-1
SAMPLING
STATION
Figure 4-11. Sketch of land treatment site showing designations
at pore-liquid sampling sites (SWC1 = southwest corner;
NE1 = northeast corner; EMI = east-middle of field)
-------
BACKGROUND
2 SOIL PORE-LIQUID
MONITORING DEVICES
FOR EACH SOIL SERIES
ACTIVE
6 SOIL PORE-LIQUID
MONITORING DEVICES
PER UNIFORM AREA
INITIAL SOIL SURFACE
30cm
(12 in)
COMPOSITE 2 PORE-LIQUID
SAMPLES TO GET 1 SAMPLE
PER SOIL SERIES
TREATMENT ZONE
1.5m
(5ft)
UNSATURATED
ZONE
AT LEAST
1m
(3ft)
COMPOSITE 2 PORE-LIQUID
SAMPLES TO GET 3 SAMPLES
PER UNIFORM AREA
SEASONAL HIGH WATER TABLE
Figure 4-12. Pore liquid sampling depths
-------
LAND SURFACE
SCREENED BACKFILL
*
/ / / //
BENTONITE'
•^ ;vx i;; j.*^:; •;: ::i" t^.
-^ 200-MESH SILICA SAND
»yV-'.'' DCMTrMVIITC
Figure 4-13. Location of suction lysimeters
78
-------
no greater than 30 centimeters (12 inches) below the treatment
zone (Figure 4-13).
(2) Samples from each of the soil-pore liquid monitoring devices
should be collected and analyzed at least quarterly unless the
wastes are applied very infrequently. If liquid is not
present at a regularly scheduled sampling event, the monitor-
ing device should be evacuated prior to and checked within 24
hours following each significant waste application or rainfall
event, and a sample drawn when sufficient liquid is present.
(3) Composite the soil pore-liquid samples from each uniform area
in pairs to form a minimum of three samples for analysis.
However, if a uniform area is greater than 5 hectares, a
minimum of one composite sample per 1.5 hectares should be
formed.
4.6 INSTALLATION PROCEDURES FOR VACUUM-PRESSURE PORE-LIQUID SAMPLERS
4.6.1 Constructing Trenches and Instrument Shelters
On background areas, samplers may be installed in a borehole excavated
by one of the augering methods described in Section 3. Similarly, at such
sites, the accessories, such as vacuum-pressure and discharge lines, could be
located directly above or adjoining the access hole. Such a simple installa-
tion may not be possible for the active portion of the land treatment units
because of operational problems and sampling bias. In order to avoid damage
to the sampler and access tubes in the active portion, it will be necessary
to construct a trench from each unit to bring the lines to a convenient
access point out of the active portion. This trench should be constructed to
a depth below the operating depths of soil tilling equipment, subsurface
injection equipment, or other manipulative equipment.
The sampling unit should be installed on an angle whenever possible in
about 30 cm (1 ft) or more of undisturbed soil to the side of the shaft, such
as illustrated in Figure 4-14. Using one of the previously described hand
augers, a hole should be made at an angle of 30 to 45° from horizontal into
the side of the trench. Installed in this manner, an undisturbed soil column
will be retained above the sampler. In addition, this angular placement will
improve the sampler's ability to collect non-Darcian, macropore flow. Given
that the maximum depth at which to locate the sampling point of pore-liquid
samplers should be 30 cm (1 ft) below the treatment zone (EPA, 1983b), the
maximum total depth of each sampling point (i.e., suction-cup) should be
about 1.67 m (5.5 ft) below the land surface.
Construction of a 1.5 m (5 ft) deep trench, which may be up to 10 m (30
ft) in length will require the use of trenching equipment. Available trench-
ing devices in shallow trenches include backhoes and travelling bucket
trenches such as the "ditch witch." The exact grade on the bottom of the
trench is not critical, but it may be helpful to survey in the total cut
required at certain distances along the trench.
Because members of the field crew will be required to stand in the trench
for installing the samplers, it is advisable to provide a convenient open
working space, such as 1.82 m (6 ft) by 1.82 m (6 ft), at the sampling point.
Consequently, a backhoe should be used to construct a shaft with approximate
79
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SHELTER
00
o
m
SM;
II
TOP VIEW
SHELTER
SHAFT OPENING
6ftx6ftx5ft
CONDUIT TO PROTECT
SAMPLER ACCESS LINES
30cm(1 ft)
PORE-LIQUID SAMPLER
SIDE VIEW
Figure 4-14.
Views of trench and access shafts at pore-liquid
sampler sites on active land treatment site
-------
dimensions of 1.81 m (6 ft) by 1.81 m (6 ft) by about 1.5 m (5 ft) at each
sampling location. Such a shaft will also provide safety of minimizing the
possibility of the walls caving in on personnel bent over in the hole. The
shaft will be backfilled when installation is complete.
It is highly advisable to locate the terminal components of the sampling
units in some type of shelter for protection against poor weather and vandal-
ism. A simple shelter with the sampler leads exposed may be satisfactory. A
portable pressure/vacuum hand pump (see Figure 4-4) could be used to pull the
sample. Two types of more costly engineered shelters are shown in
Figures 4-15 and 4-16. The above-ground shelter consists of a metal plate
housing with a metal door secured by a lock. The housing is of large enough
dimensions to permit storing sample bottles for as many units as will be
terminated in the shelter, plus a space for vacuum and pressure bottles if
such bottles are used in lieu of hand pumps.
The below-ground type of housing consists of a metal box buried in the
access road, with the lid just below land surface. A hinged metal lid is
attached with a locking device. The rationale of this construction is that
the unit is out of sight, particularly if the lid is covered with earth.
This technique is particularly advantageous where vandalism is a problem.
Again, the internal dimensions should be large enough for sample bottles and
vacuum/pressure tanks.
The following three stages of installing a vacuum-pressure pore liquid
sampler are discussed below: 1) installing vacuum-pressure and discharge
lines, 2) installing the sampler into the ground, and 3) backfilling the
trench.
4.6.2 Installing Access Lines
The approximate length of the two lines in each sampler should be deter-
mined by measuring the distance between the installation point and the above-
ground access point (e.g., shelter). The lines should be cut to this length
plus an allowance for the distance that the tubes will extend into the sampler.
Some excess should be retained at the above-ground access point. It is possi-
ble to lay the tubing directly into the trench, however, the tubes may crimp in
dry soils. The tubes should be installed into a PVC or metal manifold consis-
ting of small diameter conduit. Although the conduit does provide some struc-
tural protection from compression, the main function of the conduit is to
discourage rodents, etc., from physically damaging the leads. A convenient
method for leading the tubes through the conduit is to first run a cord through
the tube, attach the cord to the two lines, and then pull the lines through the
conduit. One method for installing the cord is to attach one end to a rubber
cork at slightly smaller diameter than the inside diameter of the conduit, then
blowing the cork and cord through the conduit using compressed air.
The procedure for installing access tubes (Soilmoisture Equipment Corp.,
1983) into the sampler, before placing the unit in a borehole, is as follows:
When installing the tubes, one tube should be pushed through the neo-
prene plug (see Figure 4-17) so that the end of the tubing reaches almost
down to the bottom of the porous ceramic cup. This "discharge" access tube
should be marked at the other end in some fashion to identify it. The other
81
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oo
ro
STEEL HOUSING WITH
HINGED STEEL DOOR
HP
MANIFOLD HOUSING
ACCESS LINES
FROM INDIVIDUAL
SAMPLERS
VACUUM (PRESSURE) BOTTLE
PRESSURE-VACUUM
RELIEF VALVE
VALVE
EPf
SAMPLE BOTTLE
PRESSURE-
VACUUM LINES
TO PORE-LIQUID
SAMPLERS
i .•--^•;-/:;••.•:-.•;;.: •^•-":' -.'••••'•, .-". "~ CONDUIT
i :&i&i?;$. f i %& FOR BURIED
:?*?-:y-<\*-;':.f*:-?;i.i :-'-r-:-:i'.;:-;:.i Ar*r«cec i IMCC
'•***• --'^i& ACCESS LINES
Figure 4-15. Above ground shelter for sample bottles and accessories
(side view)
-------
LAYER OF EARTH
qpMtd
* O «
HINGED, STEEL DOOR
SIDE VIEW OF SHELTER
• • O
TO
SAMPLERS
PRESSURE-VACUUM
RELIEF VALVE
TANK VALVE-,
TO
SAMPLERS
VACUUM (PRESSURE) TANK
MANIFOLD WITH LINES FROM
INDIVIDUAL SAMPLERS
SAMPLE BOTTLES
BURIED CONDUIT
FOR ACCESS LINES
- STEEL
HOUSING
TOP VIEW
Figure 4-16. Burial shelter for sample bottle and accessories
83
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ACCESS TUBE
(PRESSURE VACUUM)
ACCESS TUBE
(DISCHARGE)
CLAMP RING
NEOPRENE
PLUG
NAIL OR
SIMILAR OBJECT
BODY TUBE
POROUS CERAMIC CUP
Figure 4-17. Installation of access tubes in a pressure-vacuum pore-liquid
sampler (Soilmoisture Equipment Corp., no date)
84
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"pressure-vacuum" access tube should be inserted into the neoprene plug so
that it extends through the plug perhaps one inch.
After the tubes are installed (see Figure 4-17b), tighten the ring clamp
with a nail or similar object inserted through the holes provided in the
clamps ring. Tighten only until it meets the body tube.
4.6.3 Step-by-Step Procedures for Installing Vacuum-Pressure.
Pore Liquid Samplers
The procedures included in this section are adapted from the operating
procedure for a commercially available vacuum-pressure type sampler. (These
procedures are generally applicable to similar types of commercially avail-
able units and the ensuing discussion does not constitute an endorsement of
this particular sampler.) The procedures are grouped into (a) procedures for
preparing the hole, and (b) alternative methods for installing the samplers.
4.6.3.1 Constructing the Hole--
In rock-free uniform soils at shallow depths, use a 5.08 cm (2 in) screw
or bucket auger for coring the hole (see Figure 4-14) in the side of the
trench. If the soil is rocky, a 10.2 cm (4 in) auger should be used. It
should be kept in mind that the depth of hole required for installing units
on background areas will be 1.67 m (5.5 ft). However, on the treatment areas
the holes will only be about one to three feet deep because of the hole angle
and the preliminary excavation.
The soil used to backfill around the bottom of the sampler should then
be sifted enough a £" mesh screen to remove pebbles and rocks. This will
provide a reasonably uniform backfill soil for filling in around the soil
water sampler.
4.6.3.2 Sampler Installation Procedure--
The goals of a careful installation procedure are: (1) to ensure good
contact between the suction cup portion of the sampler and the surrounding
soil, and (2) to minimize side leakage of liquid along the sampler wall.
Although numerous installation procedures have been used in the past, the
bentonite clay method is recommended as the best choice for achieving both of
these goals. This method includes a silica sand layer that ensures good
contact with the suction cup and a clay plug that prevents leakage down the
core hole and along the sampler wall.
Prior to installation, the lysimeters should be checked for leaks and
flushed with distilled water. To check for leaks, the lysimeters are totally
immersed in a tank of water. It is preferable to use a glass aquarium so that
the location of the leaks (bubbles) can be easily identified. One of the tubes
going into the suction lysimeter is clamped shut. A pressure line is attached
to the second tube. Slowly increase the pressure within the suction lysimeter
to 15 psi. On teflon lysimeters, it is important to check for leaks at all
screw fittings. In addition, the teflon cups may bubble at pressures greater
than 2 psi. Ceramic units, on the other hand, should not bubble from any
location until at least 15 psi. All leaks on teflon lysimeters should be
corrected using teflon tape. All leaks on ceramic units should be corrected by
85
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increasing the pressure at each of the fittings by screwing the pressure
couplings down. At this point it is also assumed that the cups have been
prepared and the teflon access tubes have been installed in the sampler. The
cups should be installed while they are wet.
4.6.3.3 Bentonite Clay Method—
The following is a step-by-step description of the bentonite clay install-
ation method:
(1) Core hole to desired depth.
(2) Pore in 7.6 cm to 12.7 cm (3 in to 5 in) of wet bentonite clay
to isolate the sampler from the soil below (see Figure 4-18).
(3) Pour in a small quantity of 200 mesh silica-sand slurry and
insert soil water sampler. (Slurry contains 1 Ib of silica per
150 ml of water).
(4) Pour another layer of 200 mesh silica-sand at least six inches
deep around the cup of the soil water sampler.
(5) Backfill with native soil to a level just above the soil water
sampler and again add 7.6 cm to 12.7 cm (3 in to 5 in ) of
bentonite as a plug, to further isolate the soil water
sampler and guard against possible channeling of water down
the hole.
(6) Backfill the remainder of the hole slowly, tamping continu-
ously with a long metal rod. Again backfill should be of
native soil free of pebbles and rocks.
4.6.3.4 Backfilling the Trench and Final Survey—
Upon installation of the sampler in the hole, as described above, and
the access tubes in the trench, it is time to backfill both the trench and
the shaft which were constructed around the sampling point. First, however,
it is advisable to survey in the exact location of the sampler to facilitate
recovery of the unit at some future time. Surveying in the units in back-
ground areas is also recommended. An initial vacuum should be applied to
each unit before backfilling to check for leaks and to remove water applied
to the slurry. Backfilling should be conducted in stages, using a mechanical
tamper to ensure good packing of each layer. Special care is required when
packing soil into the large hole excavated at the sampler location. It is
preferable to backfill the trench and access shaft on the same day that the
excavation is made. Delays of 1-2 days can result in a lost of soil moisture
in the excavated material and, consequently, problems may occur with packing
the soils, i.e., heavy clays. Although in time the trenches and shafts will
return to a natural bulk density, it is preferable to tamp the backfilled
material to at least the original bulk density or preferably higher. If the
bulk density is not maintained, the trenches and shaft may begin to fill with
water. In cases where the bulk density is difficult to maintain, a 25 percent
mixture of bentonite and soil should be used in the trenches and shaft. This
mixture will preclude any buildup of pooled water in the shaft and trenches.
86
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TAMP SOIL
SCREENED BACKFILL
BENTONITE
SCREENED BACKFILL
200 MESH
SILICA-SAND
BENTONITE
Figure 4-18.
Bentonite clay method of installing vacuum-pressure
pore-liquid samplers (Soilmoisture Equipment Corp.,
no date)
87
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4.7 OPERATION OF VACUUM-PRESSURE SAMPLING UNITS
Ideally, persons trained in the operation of pore-liquid samplers should
be selected for the sampling program. Individuals with a background in soil
science are desirable but not required. It is advisable to select a perman-
ent team of two individuals for the sampling program, with one individual
being responsible for the operation and the second individual being a helper.
A permanent team ensures uniformity in sample collection and chain of custody
procedures.
Prior to obtaining a sample for analysis, good quality control procedures
require that the samplers be evacuated 2-3 days ahead of the actual sampling
time. By totally removing any fluid that could have accumulated in the suction
lysimeter over time, the field technician is subsequently able to obtain a
fresh sample from the unsaturated zone. The procedures required to initially
evacuate the sampler are identical to the operational procedures identified
below.
The stages in operating a vacuum-pressure sampler are as follows:
(1) apply a vacuum to the interior of the sampler, via the vacuum-pressure
line, (2) maintain the vacuum for a sufficient period of time to collect a
sample in the sampler, (3) release the vacuum, and (4) apply a pressure to the
vacuum-pressure line and blow the sample through the sample line into a collec-
tion flask. Details on each step are included in this discussion.
Two alternatives are available for applying the vacuum and pressure during
each collection cycle. The simplest method is to use a vacuum-pressure hand
pump, with a vacuum dial. This method is suitable for collecting samples from
individual units, such as those on background areas. In cases in which the
access lines from several units are brought together into a common shelter, it
may be more convenient to use separate vacuum and pressure bottles connected to
a common manifold with outlets to the individual access lines.
The procedure described in the following paragraphs was adopted from the
operating instructions for a commercially available sampler. Use of this
procedure does not constitute an endorsement of this sampler.
(1) Close the pinch clamp on the discharge access tube (see
Figure 4-19). All pinch clamps should be tightened with
pliers to eliminate the problem of not sealing. Finger-tight
pinching of the clamps is not sufficient.
(2) Apply a vacuum to the pressure-vacuum line either by means of
a hand pump or by attaching a vacuum bottle. The applied
vacuum should be about 60 centibars (18 inches of mercury).
(3) When a steady vacuum is obtained, attach a pinch clamp to the
vacuum-pressure line. Alternatively, when a vacuum bottle is
used, it may be possible to omit using a pinch clamp in an
effort to sustain the requisite vacuum.
(4) After a period of time that is deemed sufficient to collect a
sample (a minimum of 24 hours in some cases), attach sample
bottles to the discharge line from each unit.
88
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PRESSURE
PORT
PINCH CLAMP
OPEN
(PRESS. VAC.
ACCESS TUBE)
oc
VACUUM PORT
PINCH CLAMP
CLOSED
(DISCHARGE
ACCESS TUBE)
PULLING A VACUUM
PINCH CLAMP
CLOSED
(DISCHARGE
ACCESS TUBE)
PINCH CLAMP
OPEN
(PR ESS. VAC.
ACCESS TUBE)
PRESSURE
PORT
VACUUM
PORT
PINCH CLAMP
OPEN
(DISCHARGE
ACCESS TUBE)
COLLECTED
WATER
SAMPLE
PINCH CLAMP
CLOSED
(PRESS. VAC.
ACCESS TUBE)
(0
SOIL WATER SAMPLE
(B)
Figure 4-19.
Stages in the collection of a pore-liquid sample using a
vacuum-pressure sampler (Soilmoisture Equipment Corp.,
no date)
-------
(5) Release the vacuum by opening the pinch clamp or removing the
vacuum bottle.
(6) Apply 1 to 2 atmosphere of air pressure to the pressure-vacuum
lines, either by using a hand pump or by installing a con-
tainer of compressed air, and blow the liquid sample from the
sampler into the collection flasks (see Figure 4-19).
(7) Remove and seal the flasks
The volume of sample required is dependent upon the number and kind of
analysis to be performed. It may be found during a sampling cycle that the
volume of sample obtained from a particular unit or units is not great enough
to permit analysis. Alternatively, no sample at all may be obtained. For
these cases it will be necessary to repeat each step using a greater vacuum
and longer sampling interval.
4.8 SPECIAL PROBLEMS AND SAFETY PRECAUTIONS
The successful operation of pore-liquid samplers may be restricted by
any or all of the following factors: (1) hydraulic factors, (2) soil physi-
cal properties, (3) cup-wastewater interactions, and (4) climatic factors.
4.8.1 Hydraulic Factors
The most severe constraint on the operation of pore-liquid samplers
involves the soil around the porous segment of a sampler becoming so dry that
air bubbles enter the cup and further movement of soil water into the unit is
restricted.
If the soil is not excessively dry, a usable sample may still be obtained
if suction is applied to the cup for a sufficiently long period of time.
Nevertheless, because the yield of suction samplers is greatly reduced under
very dry conditions, there may be situations in which the time required to
obtain a sufficiently large sample exceeds the maximum holding time for
analysis. Similarly, there may be cases where the soil is so dry that the
units simply will not yield a sample. This may be particularly true in arid
regions where rainfall is not great enough to wet up the soil profile. Note
that sampling should be timed to occur immediately after a rainfall or
significant waste application events which may alleviate this problem in
certain cases.
4.8.2 Physical Properties: Soil Texture and Soil Structure
Soil texture refers to the relative proportion of the various soil
preparates (particles 2 mm) in a soil (EPA, 1983b). Examples of soil
texture classes include silt loam, silty clay, and sand. The successful
operation of suction samplers requires a continuity between pore sequences in
the porous segment of the sampler and those in the surrounding soils. When
soils are very coarse-textured, a good contact between the porous segment of
a sampler and the fine pore sequences may be difficult to maintain and the
flow continuum may be destroyed. Unlike the problem of sampling in very dry
soils, the problem of poor soil contact is mainly an operational problem
which can be circumvented by using the recommended method of cup installation
90
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(see Figure 4-18). In this method, the porous segment of the sampler is
placed in close contact with the silica sand, which in turn contacts a larger
area of the surrounding soil. This method helps to maintain a continuity in
the flow paths that soil water follows in moving from the soil through the
silica sand and porous segment into the interior of the sampler.
Soil structure refers to the aggregation of the textural units into
blocks. A well-structured soil has two distinct flow regions for liquids
applied at the land surface: (1) through the cracks between blocks, i.e.,
interpedal flow, and (2) through the finer pore sequences inside the blocks,
i.e., interpedal flow. Liquids move more rapidly through the cracks than
through the fine pores. Because of the rapid flushing of pollutants through
larger interconnected soil openings, the movement of liquid-borne pollutants
into the finer pores of the soil blocks may be limited. Inasmuch as suction-
cup samplers collect water from these finer pore sequences, the resultant
samples will not be representative of the bulk flow.
A primary goal of soil-pore liquid sampling is to detect the presence of
fast moving hazardous constituents. This goal may not be realized if samp-
lers are placed in highly structured soils leading to a flow system such as
that described in the last paragraph. The structure of a soil profile is
best examined by constructing trenches near the proposed monitoring sites to
a depth corresponding to the maximum depth at which the sampling segments
will be installed. The extent of large interpedal cracks should be docu-
mented at each profile. If such cracks appear to be widespread, alternative
sites or monitoring techniques (e.g., pan lysimeters) should be examined.
However, it should be borne in mind that even large cracks frequently dimin-
ish in width in deeper reaches of the profile. If it is found that structur-
al cracks "pinch out" at the monitoring depth, suction samplers could be
installed. As mentioned previously, the extent of macropore flow should be
examined in the treatment demonstration to determine the appropriate monitor-
ing approach (i.e., suction or pan lysimetry) and to evaluate the acceptabil-
ity of the site for land treatment.
4.8.3 Cup-Wastewater Interactions
For simplicity, the interactions between pore-liquid samplers and waste-
water can be grouped into (1) those affecting the operation of the porous
segment, principally by plugging, and (2) those that change the composition of
pollutants moving through the porous segment.
4.8.3.1 Plugging--
A basic concern in the use of porous type samples to detect the movement
of hazardous waste substances in soils is that the porous segment may become
plugged either by particulate matter (e.g., fine silt and clay) moving with the
liquid, or because of chemical interactions. The problem of clogging by
particulate matter is not as severe as once thought. Apparently, soils have
the capacity to filter out the fine material before reaching the porous seg-
ments. Several studies have been reported involving the use of suction-type
samplers for monitoring pollutant movement at land treatment units. Generally,
it appears that the sampling units operated favorably without clogging by
particulate matter. An example of such studies include those by (1) Smith and
McWhorter (1977), in which ceramic candles were used to sample pollutant
91
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movement in soil during the injection of liquid organic wastes; (2) Grier,
Burton, Tiwari (1977) involving the use of depth-wise suction samplers on
fields used for disposal of animal wastes; and (3) Smith et al. (1977), in
which depth-wise suction samples were installed in fields irrigated with wastes
from potato processing plants.
Chemical reactions at the surface of a suction sampler may clog the
porous network. One type of chemical reaction is precipitation (e.g., of
ferric compounds). However, considering the wide variety of chemical wastes
which are disposed of at land treatment units, other effects are also possi-
ble, leading to the inactivation of suction samplers.
The operator of a land treatment facility may wish to determine the
possibility of clogging from either particulates or chemical interactions
before installing units in the field. For example, test plots could be
employed (e.g., plots intended for the "treatment" demonstration). A cluster
of suction samplers should be installed in the monitoring zone at each plot
and waste applied at the proposed rate. The yield of each cup should be
determined throughout the trial. Devices for measuring the suction of the
soil water (e.g., tensiometers) should also be installed to ensure that the
soil-water suction is within the operating range of the cups. This will
demonstrate that cups fail to operate because of clogging and not because the
soil is too dry.
Even though suction samplers may fail because of clogging, the problem
may still be an operational difficulty that can be overcome. For example,
installing silica sand around the cup may filter out particulate matter.
Unless this filter becomes clogged, the samplers should continue to operate.
However, this approach may not be sufficient to prevent clogging by chemical
interactions.
4.8.3.2 Change in the Composition of Hazardous Constituents During
Movement Through Pore-Liquid Samplers--
It is fairly-well established that the porous segments of suction
samplers filter out bacteria but not virus. Similarly, a reduction may occur
in the metal content of liquids moving into samplers because of interactions
within the porous segment. This problem can be reduced by acid leaching the
cups before they are installed in the field, as described in another section
of this report.
Because a major concern at land treatment areas is the fate of hazardous
organic constituents, the amount of organic-cup interactions should be
estimated before field installing sampling units. Change in the composition
of hazardous constituents during liquid moving through suction samplers can
be demonstrated by laboratory studies. Basically, during such studies
suction samplers are placed in liquids of known composition contained in
beakers. Samples are drawn into the cups and extracted for analysis. The
change in composition is then easily calculated. In preparing these tests it
is essential that each cup be preconditioned in accordance with recommended
practice, i.e., flushing with 8N HC1, followed by rinsing with distilled
water.
92
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4.8.4 Climatic Factors
A major factor limiting the operation of suction samplers in very cold
climates is that the soil water may become frozen near the cups. This means
that a sample cannot be obtained during freezing conditions. Another undocu-
mented problem which conceivably could occur is freezing of samples within
the cups and lines, so that the samples cannot be brought to the surface.
Since the samplers are located at depths greater than 1.5 m (5 ft), it is
unlikely that freezing would occur at this depth. Prior to winter setting
in, the lines should be flushed. Inasmuch as land treatment is not recommen-
ded during winter months in very cold regions these problems may be academic.
Another effect of freezing temperatures is that some soils tend to heave
during freezing and thawing. Consequently, suction samplers may be displaced
in the soil profile, resulting in a break in contact. In addition, if the
cups are full of liquid when frozen, the cups may be fractured as a result of
expansion of the frozen liquid. The extent of these problems, however, has
not been determined.
4.8.5 Safety Precautions
Worker safety is of paramount importance when installing systems of
pore-liquid samplers in active land treatment sites, and during sample
handling. In some cases all contact with the waste and liquid samples should
be avoided, and toxic fumes should not be inhaled. Similarly, certain wastes
are highly flammable and precautions should be taken to avoid creation of
sparks. No smoking should be allowed. The degree of precaution that should
be exercised, including the type of protective clothing, must be decided on a
case-by-case basis. Further safety precautions are discussed in Section 3.
4.8.6 Lysimeter Failure Confirmation
In the event that a sample cannot be retrieved from an installed suction
lysimeter under conditions where the operator knows that the soil suction
levels should be high enough to obtain a sample, such as after a major rainfall
event, specific procedures should be followed. Adjacent to a suction lysimeter
that appears to have failed, a soil suction determination must be made to
determine if the available soil moisture is high enough to obtain a sample.
Soil suctions are determined using tensiometers. Tensiometers are commercially
available and are produced with various designs and lengths.
A tensiometer consists of a tube with a porous ceramic tip on the bottom,
a vacuum gauge near the top, and a ceiling cap. When it is filled with water
and inserted into the soil, water can move into and out of the tensiometer
through the connecting pores in the tip. As the soil dries and water moves out
of the tensiometer, it creates' a vacuum inside the tensiometer, which is
indicated on the gauge. When the vacuum created equals the "soil suction,"
water stops flowing out of the tensiometer. The dial gauge reading is then a
direct measure of the force required to move the water from the soil. If the
soil dries further, additional water moves out until a higher vacuum level is
reached. When moisture is added to the soil, the reverse process takes place.
Moisture from the soil moves back into the tensiometer through the porous tip
until the vacuum level is reduced to equal the lower soil suction value, then
water movement stops. If enough water is added to the soil so that it is
93
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completely saturated, the gauge reading on the tensiometer will drop to zero.
Because water can move back and forth through the pores in the porous ceramic
tip, the gauge reading is always in balance with the soil suction.
The effective operational range for suction lysimeters is between satura-
tion and 60 centibars of suction as determined by the tensiometer. Above 60
centibars of suction, a ceramic lysimeter will operate. However, the flow
rates will be so low that effectively one cannot get a sample. If the tensi-
ometer readings are between 0 and 60 centibars of suction, the suction lysime-
ter should obtain a sample. If no sample is obtained under these soil suction
ranges, the suction lysimeter will be deemed to have failed and should be
excavated or abandoned.
Tensiometers can be readily installed in the soil adjacent to the suspect
suction lysimeter by using conventional soil sampling tools. The body tube and
porous sensing tip of tensiometers are 7/8" (2.2 centimeters) in diameter.
Installation must be made so that the porous ceramic sensing tip is in tight
contact with the soil. Commercially available insertion tools can be used in
rock-free soils. Standard 1/2" (U.S.) steel pipe can also be used to drive a
hole into the soil to accept the tensiometer. In rocky soils a soil auger can
be used to bore a larger hole and then the soil is sifted and packed around the
porous ceramic tip to make good contact before the hole is backfilled. The
surface soil is tightly tamped around the body tube to seal surface water from
entering. The tensiometers should be installed at a depth of approximately 1.6
meters so that they will be reading soil suction conditions at the depth of the
installed suction lysimeter. Tensiometers require 2-3 hours to come into
balance with the ambient soil suction. As such, the tensiometers should be
read 3 hours after their initial installation. Tensiometers can be left in
place in the field over a couple of waste spreading periods to determine if the
soil suction is high enough for the suction lysimeters to operate and to obtain
a sample.
4.9 PAN LYSIMETER INSTALLATION AND OPERATION
As mentioned above, pan lysimeters are more effective in soils in which
macropore flow dominates. The two pan lysimeters which appear to have the most
application is the trench lysimeter and the free drainage glass block sampler.
Parizek (Parizek and Lane, 1970) is responsible for the majority of the avail-
able information on trench lysimeters, while Barbee (1983) is the principle
author of the research on glass block samplers. Other devices are being
developed (i.e., drum lysimeters) which should be considered as part of a
monitoring system.
4.9.1 Trench Lysimeters
Trench lysimeters are lysimeters made of galvanized, 16-gauge metal, with
dimensions of 0.305 x 0.45 m (12x15 inches) that are installed in a trench.
Parizek and Lane (1970) developed an installation technique for these devices
(see Figure 4-20). Their approach includes installing the trench lysimeter in
the sidewall of a trench shelter. Copper tubing is soldered to a raised end of
the pan to allow soil water to drain into a sample container located inside the
sampling pit. The trench shelter is covered with a sloping roof and a ladder
is placed at one end of the house to allow access for sampling.
94
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PLYWOOD ROOF WITH
GALVANIZED
SHEET METAL COVER
A ,
PAN LYSIMETER
2 x 12-inch siding and 4 x 4-inch
timbers. All wood treated with
with preservative.
.GUTTER DRAIN PIPE
PEAGRAVEL-
m
\ .PLASTIC |
-{TUBING I
2-inch O.D. PIPE
.:.: RESIDUAL SOIL
~ --•' STRATIFIED SILT,
i_T.••:z.'... CLAY, AND SAND
-SCREEN ON
FLOOR DRAIN
DOLOMITE BEDROCK
Figure 4-20. Trench lysimeters installed in trench shelter
(Parizek and Lane, 1970)
95
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The design by Parisek and Lane (1970), however, introduces a sampling bias
problem. If the trench lysimeters are installed close to the side of the
trench shelter, as represented in Figure 4-20, the collected sample will be
biased. This bias results from the fact that the trench shelters, which
project above the land surface, will cause waste application equipment to avoid
the actual sampling area to prevent damage to the shelter. To alleviate this
problem, a slightly modified installation approach is recommended below.
Figure 4-21 illustrates the recommended installation approach for pan
lysimeters, including trench lysimeters and glass block samplers. At a random-
ly selected site, dig a 1.22 m (4 ft) wide, 3.66 m (12 ft) long trench, exca-
vated to a depth of 2.44 m (8 ft). The trench sidewalls should be temporarily
supported with timbers and siding to reduce the risk of cave-ins. The entire
seepage face should be inclined 1 to 5 degrees from the vertical.
The trench lysimeter is installed into the sidewall of the trench at a
level that is below the treatment zone (s 1.5 m from the soil surface), but a
significant distance above the trench floor (see Figure 4-21). A discharge
line is installed from the trench lysimeter to a discharge point at the sur-
face. The distance between the lysimeter and the discharge point should be at
least 10 m (30 ft) to preclude any.sampling bias above the lysimeter. When a
sample is required, a vaccum is placed on the discharge line and a sample is
retrieved.
After the sampling lines are installed, the lysimeter installation trench
is backfilled according to the same procedures described below for glass block
samplers.
4.9.2 Free Drainage Glass Block Samplers
One technique for measuring gravitational water in the unsaturated zone
was developed by Barbee (1983). The hollow glass block free drainage sampler
was developed as a technique for improving the capability for monitoring fluid
movement in the unsaturated zone.
The free drainage sampler is made from a hollow glass block (obtained from
the PPG Company, Houston, Texas 77020) 30 cm by 30 cm by 10 cm deep with a
capacity of 5.5 liters (Figure 4-10). A rim, approximately 0.158 cm high
around the edge of the upper and lower surfaces, enhances the collecting
effectiveness of the blocks. To collect a sample, nine 0.47 cm diameter holes-
are drilled near the edge around the upper surface of the block. The block is
then thoroughly washed with distilled water. A 0.47 cm OD nylon tube is then
inserted into the block and coiled on the bottom so that all the accumulated
liquid can be removed. A sheet of 0.158 cm thick fiberglass is cut to fit over
the upper surface, including the holes, without overhanging the edge. This
sheet enhances contact with the overlying soil and also prevents soil from
contaminating the sample and plugging the holes.
The sampler is installed by digging a 2.44 m (8 ft) deep trench with a
backhoe at a randomly selected site. A tunnel of about 45 cm is then excavated
into the side of the trench below the treatment zone (s 1.5 m from the soil
surface), but a significant distance above the trench floor (see Figure 4-21).
The tunnel is correctly sized by using a wood model slightly larger than the
glass block. Extreme care is taken to keep the ceiling of the tunnel level and
96
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SAMPLING TUBE
INSTALLATION TRENCH
(BACKFILLED AFTER LYSIMETER INSTALLATION)
\
SAMPLE LINE
-*< • 9^f V • • ^ *
TREATMENT%
^ 4 I /
1 J /
WATER TARi F TRENCH LYSIMETER
WM i CMI ABLt QR GLASS BLOCK
^ i u ni y
>1 m
Figure 4-21. Pan lysimeter installation
-------
smooth to ensure water will not run off the block and also to have a smooth
surface against which the block can be pressed. Jordan (1968) noted that
unless the edges of the free drainage sampler are in firm contact with the soil
for the entire perimeter of the sampler, water will tend to run out through
spaces between the sampler and soil, particularly if the ceiling of the tunnel
has many irregularities. In clay soil it is necessary to use a small knife to
lightly score the ceiling of the tunnel because of smearing and compaction of
the surface during excavation. One glass block is then carefully placed in the
tunnel and then pressed firmly against the ceiling, being held in place by soil
packed tightly beneath and to the sides of it.
The sampling lines must be carefully installed to prevent sampling bias.
The nylon sampling tube is run underground in a trench approximately 10 m to a
sampling location (see Figure 4-21). The trench for the sampling tubes usually
need only be approximately three feet (1 meter) deep to prevent damage from
operating equipment. The nylon sampling tube is then run to the soil surface
and a sample drawn by applying a vacuum.
After installation, the trenches for sampling line and lysimeter installa-
tion are backfilled. Prior to backfilling the lysimeter installation trench,
aluminum foil, 46 cm wide, should be pressed against the side of the trench
into which the lysimeter was installed. The aluminum foil prevents lateral
movement of liquid from the backfijled soil into the undisturbed soil above the
glass block lysimeter. Any temporary sidewall support structures may be
removed prior to backfilling the trench. Careful attention should be paid to
properly tamp the soil in the trench after backfilling.
4.10 PAN LYSIMETER LIMITATIONS
Pan lysimeters will only function when the soil moisture is greater than
field capacity. This implies that their use must coincide with a continuously
wetted soil with most of the flow occurring through macropores (i.e., cracks).
This situation could exist at certain land treatment sites at which highly
structured soils are present in the treatment zone. If macropore flow is
predominant, however, the successful completion of the treatment demonstration
may be difficult.
Pan lysimetry will, as noted previously, only sample gravitational water.
The timing for sample collection will be within hours of a precipitation event.
Because the pan lysimeter is a continuous sampler, the device should be emptied
after each precipitation event in order to prevent sample loss. Because of the
limited experience with pan lysimetry there is little knowledge of clogging
potential or effective operating life. Macropore flow bypass of the treatment
zone or suction lysimeter, if it occurs, should be identifiable during initial
precipitation events in the treatment demonstration.
4.11 DATA ANALYSIS AND EVALUATION
Appendix B describes the chain of custody documentation and control to
identify and trace a sample from sample collection to final analysis.
Appendix C provides example summary sheets for the analytical and statistical
results from unsaturated zone monitoring. Summary sheets, such as these,
should be included in the operating record of the facility.
98
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The statistical evaluation of the pore-liquid sample analysis follows the
same procedures as defined in Section 3.8. Details of the methods are not
discussed here because standard reference materials and computer packages can
be used to conduct the analysis. Using equations 1-3 of Section 3.8, the mean,
variance and confidence interval are determined. Using equations 4-5 of that
section, the Student's t-test can be applied to determine if hazardous consti-
tuent levels below the treatment zone in the active portion are statistically
increased over levels in the background area.
99
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Anderson, J.L. and J. Bouma, 1977. Water Movement Through Pedal Soils: I.
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Art's Machine Shop, 1982. Soil Sampling Augers, Ground Water Monitoring
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Art's Machine Shop, 1983. Personal Communication, American Falls, ID.
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Barbee, G.C, 1983. A Comparison of Methods for Obtaining "Unsaturated
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Guide, U.S. EPA, EMSL, ORD, Las Vegas, NV, DER-0155 (84).
Bear, J., D. Zaslavsky and S. Irrnay, 1968. Physical Principles of Water
Percolation and Seepage, United Nations Educational, Scientific and
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Beven, K. and P. Germann, 1981. Water Flow in Soil Macropores. 2. A
Combined Flow Model. J. Soil Sci. 32:15-29.
Biggar, J.W., and D.R. Nielsen, 1976. Spatial Variability of the Leaching
Characteristics of a Field Soil, Water Resour. Res., 12(1), 78-84.
Black, C.A., (ed), 1965. Methods of Soil Analyses, (in two parts), Agronomy
No. 9, Am. Soc. of Ag., Madison, Wl.
Bodman, G.B. and E.A. Colman, 1943. Moisture and Energy Conditions During
Downward Entry of Water Into Soils. Soil Sci. Soc. Am. Proc. 8:116-122.
Bohn, H.L., B.L. McNeal, and G.A. O'Connor, 1979. Soil Chemistry, Wiley
Interscience, NY.
Bouma, J., A. Jongerius, and D. Schoondebeek, 1979. Calculation of
Hydraulic Conductivity of Some Saturated Clay Soils Using Micromorpho-
metric Data. Soil Sci. Soc. Am. J. 43:261-265.
R-l
-------
Bouma, J., and J.H.M. Wosten, 1979. Flow Patterns During Extended Saturated
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Bouwer, H., 1978, Groundwater Hydrology, McGraw-Hill, NY, 480 pp.
Briggs, L.J., and A.G.-McCall, 1904. An Artificial Root for Inducing
Capillary Movement of Soil Moisture. Science 20: 566-569.
Childs, E.C., 1969, An Introduction to the Physical Basis of Soil Water
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Doucette, W., 1984, Personal Communication, TRW Inc., RTP, NC.
Duke, H.R., and H.R. Haise, 1973. Vacuum Extractors to Assess Deep Percola-
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Dunlap, W.J., and J.F. McNabb, 1973. Subsurface Biological Activity in Rela-
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OR.
Edwards, W.M., R.R. Van Der Ploeg, and W. Ehlers, 1979, A Numerical Study
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-------
Hall, W.A., 1955. Theoretical Aspects of Water Spreading. Am. Soc. Aq.
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R-4
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R-7
-------
APPENDIX A
Table of Random Units
(Standard Mathematical Tables, 1973)
-------
TebU of Random Unitt
RANDOM UNITS
U*« of Table. If one wiahea to select a random sample of tf items from a universe of
M items, the following procedure may be applied. (M > N.)
1. Decide upon some arbitrary scheme of selecting entries from the table. For exam*
pie, one may decide to use the entries in the first line, second column; second line, third
column; third line, fourth column; etc.
2. Assign numbers to each of the itema in the universe from 1 to M. Thus, if M =*
500, the itema would be numbered from 001 to 500, and therefore, each designated item is
associated with a three digit number.
3. Decide upon some arbitrary scheme of selecting positional digits from each entry
chosen according to Step 1. Thus, if M » 500, one may decide to use the first, third, and
fourth digit of each entry selected, and as a consequence a three digit number is created
for each entry choice.
4. If the number formed is SJf, the correspondingly designated item in the uni-
verse is chosen for the random sample of N items. If a number formed is >M or is a
repeated number of one already chosen, it is passed over and the next desirable number
is taken. This process is continued, until the random sample of N items is selected.
A-l
-------
Table of Random Units
LiM/Col.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
l«
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
36
36
37
38
39
40
41
42
43
44
45
46
47
48
49
_ »
(1)
10480
22368
24130
42167
37570
77921
99662
96301
89579
85475
28918
63553
09429
10365
07119
51085
02368
01011
52162
07056
48663
54164
32630
29334
02488
81525
29676
00742
05366
91921
00582
00725
69011
25976
09763
91567
17955
46603
92157
14677
98427
34914
70060
53976
76072
90725
64364
08962
95012
15664
^•^^•••B
(2)
15011
46573
48360
93093
39975
06907
72905
91977
14342
36857
69578
40961
93969
61129
97336
12765
21382
54092
53916
97628
91245
58492
32363
27001
33062
72295
20691
57392
04213
26418
04711
69884
65797
57948
83473
42595
56349
18584
89634
62766
07523
63976
28277
54914
29515
52210
67412
00358
68379
10493
MBBBiHHBBBB
(3)
01536
25595
22527
06243
81837
11008
56420
05463
63661
43342
88231
48235
52636
(4)
02011
85393
97265
61680
16656
42751
69994
07972
10281
53988
33276
03427
92737
87529 i 85689
71048
51821
08178
51259
52404 i 60288
33362
46369
33787
85828
22421
05597
87637
28834
04839
68086
39064
25669
64117
87917
62797
95876
29888
73577
27958
90999
18845
94824
35605
33362
88720
39475
06990
40980
83974
33339
31662
93526
94904
58586
09998
14346
74103
24200
87308
07351
96423
26432
66432
26422
94305
77341
56170
55293
88604
12908
30134
49127
49618
78171
81263
64270
82765
46473
67245
07391
29992
31926
25388
70765
20492 1 38391
(5)
81647
30995
76393
07866
06121
27756
98872
18876
17453
53060
70997
49626
88974
48237
77233
77452
89368
31273
23216
42898
09172
47070
13363
58731
19731
24878
46901
84673
44407
26766
42206
86324
18988
67917
30883
04024
20044
02304
84610
39667
01638
34476
23219
68350
58745
65831
14883
61642
10593
91132
MMM^^^^
(6)
91646
89198
64809
16376
91782
53498
31016
20922
18103
59533
79936
69445
33488
5X267
13916
16308
19885
04146
14513
06691
30168
25306
38005
00256
92420
82851
20849
40027
44048
25940
35126
88072
27354
48708
18317
86385
59931
51038
82834
47358
92477
17032
53416
82948
25774
38857
24413
34072
04542
21999
^^••^^^^^
(7)
69179
27982
15179
39440
60468
18602
71194
94595
57740
38867
56865
18663
36320
67689
47564
60756
55322
18594
83149
76988
90229
76468
94342
45834
60952
66566
89768
32832
37937
39972
74087
76222
26575
18912
28290
29880
06115
20655
09922
56873
66969
87589
94970
11398
22987
50490
59744
81249
76463
59516
^•^^^^^H
(8)
14194
53402
24830
53537
81305
70659
18738
56869
84378
62300
05859
72695
17617
93394
81056
92144
44819
29862
98736
13602
04734
26384
28728
15398
61280
14778
81536
61362
63904
22209
99547
36086
08625
82271
35797
99730
20542
58727
25417
56307
98420
40836
25832
42878
80059
83765
92351
35648
(9)
62590
93965
49340
71341
49684
90655
44013
69014
25331
08158
90106
52180
30015
01511
97735
49442
01188
71585
23495
51851
59193
58151
35806
46557
50001
76797
86645
98947
45766
71500
81817
84637
40801
65424
05998
55536
18059
28168
44137
61607
04880
32427
69975
80287
39911
55657
97473
56891
54328 02349
81652 1 27195
^^^•••••••^^^^^^H
(10)
36207
34095
32081
57004
60672
15053
48840
60045
12566
17983
31595
20847
08272
26358
85977
53900
65255
85030
64350
46104
22178
06646
06912
41135
67658
14780
12659
96067
66134
64568
42607
93161
59920
69774
41688
84855
02008
15475
48413
49518
45586
70002
rtjgaj
^^oo^
88267
96189
14361
89286
69352
17247
48223
^^^^^^^^^H
(ID
20969
52666
30680
00849
14110
21916
63213
18425
58678
16439
01547
12234
84115
85104
29372
70960
64835
51132
94738
88916
30421
21524
17012
10367
32586
13300
92259
64760
75470
91402
43808
76038
29841
33611
34952
29080
73708
56942
25555
89656
46565
70663
19661
47363
41151
31720
35931
48373
28865
46751
(12)
99570
19174
19655
74917
06927
81825
(13)
91291
(14)
90700
39615 i 99505
63348158629
97758
01263
44394
16379
54613
42880
21069 i 10634 1 12952
84903
44947
11458
85590
90511
42508 ! 32307
05585)56941
18593
91610
33703
164952
78188
90322
27156 j 30613 1 74952
20285129975189868
74461
63990
28551 1 90707
75601
40719
44919 1 05944 1 55157
01915 1 92747
17752
19609
61666
15227
64161
07684
86679
87074
57102
64584
35156
25925
99904
96909
18296
36188
50720
79666
80428
9oOwo
66520 34693
42416
76655
65855
80150
54262
37888
09250
83517
53389
21246
20103
04102
88863
72828
46634
14222
57375
04110
45578
07844
62028
64951
35749
58104
32812
44592
22851
18510
94953
95725
25280
98253
90449
69618
76630
77919 j 88006
12777 i 48501
85963
38917
79656
36103
20562
03547
88050
73211
42791
87338
35509120468
77490
46880
77775
00102
06541
60697
56228
23726
78547
14777 1 62730
22923132261
^^^^^_—— ___^^^^^^^—
18062
45709
69348
66794
97809
59583
41546
51900
81788
92277
85653
^MMMMb
A-2
-------
Table of Random Units
Line/Col.
51
52
53
54
55
56
57
58
59
60
6i
82
83
64
95
M
87
as
99
70
7t
72
73
74
75
7B
t w
77
78
79
80
81
82
83
84
85
80
87
88
89
90
91
92
93
94
95
9e
97
98
99
(1)
16408
18629
73115
57491
30405
16631
96773
38935
31624
78919
03931
74426
09066
42238
16153
21467
21581
55612
44657
91340
91227
50001
66390
27504
37169
11 VIA
HiMiO
37449
46615
30986
63798
82486
21885
60336
43937
97656
03299
79626
35636
18039
08362
79556
92608
23982
09915
50937
42488
46764
03237
86591
(2)
81899
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A-3
-------
APPENDIX B
Chain of Custody
-------
CHAIN OF CUSTODY CONSIDERATIONS
The previous sections of this report described the sample collection
features of a soil-core sampling protocol. The other element of an overall
sampling protocol involves chain of custody procedures, essentially for
tracing the path of a given sample from the moment of collection through all
the intervening processes required to deliver the specimen to an analytical
laboratory. (Transmission of the sample through the laboratory involves
another host of quality assurance and quality control processes which are
beyond the scope of this section.)
Chain of custody procedures are carefully prescribed in the EPA document
entitled "Test Methods for Evaluating Solid Wastes" (EPA, 1982). The appro-
priate sections dealing with solids handling are reproduced below.
Chain of custody establishes the documentation and control necessary to
identify and trace a sample from sample collection to final analysis. Such
documentation includes labeling to prevent mix up, container seals to prevent
unauthorized tampering with contents of the sample containers, secure cus-
tody, and the necessary records to support potential litigation.
Sample Labels
Sample labels (Figure B-l) are necessary to prevent misidentification of
samples. Gummed paper labels or tags are adequate. The label must include
at least the following information:
Name of collector
Date and time of collection
Place of collection
Collector's sample number, which uniquely identifies the sample.
Sample Seals
Sample seals are used to preserve the integrity of the sample form the
time it is collected until it is opened in the laboratory. Gummed paper
seals may be used for this purpose. The paper seal must include, at least,
the following information:
Collector's name
Date and time of sampling
Collector's sample number. (This number must be identical with the
number on the sample label.)
The seal must be attached in such a way that it is necessary to break it
in order to open the sample container. An example of a sample seal is shown
in Figure B-2.
B-l
-------
Collector Collector's Sample No.
Place of Collection
Date Sampled Time Sampled
Field Information
Figure B-l. Example of sample label (EPA, 1982)
B-2
-------
NAME AND ADDRESS OF ORGANIZATION COLLECTING SAMPLES
Person Collectors
Collecting Sample Sample No.
(Signature)
Date Collected Time Collected
Place Collected
Figure B-2. Example of official sample seal (EPA, 1982)
B-3
-------
Field Log Book
All information pertinent to a field survey and/or sampling must be
recorded in a log book. This must be a bound book, preferably with consecu-
tively numbered pages that are 21.6 by 27.9 cm (8£ x 11 in.). Entries in the
log book must include at least the following:
Purpose of sampling (e.g., surveillance, contract number)
Location of sampling point
Name and address of field contact
Producer of waste and address if different than location
Type of process (if known) producing waste
Type of waste (e.g., sludge, wastewater)
Suspected waste composition including concentrations.
Number and volume of sample taken
Description of sampling point and sampling methodology
Date and time of collection
Collector's sample identification number(s)
Sample distribution and how transported (e.g., name of
laboratory, UPS, Federal Express)
References such'as maps or photographs of the sampling site
Field observations
Any field measurements made (e.g., pH, flamability,
explositivity).
Sampling situations vary widely. No general rule can be given as to the
extent of information that must be entered in the log book* A good rule,
however, is to record sufficient information so that someone can reconstruct
the sampling without reliance on the collector's memory.
The log book must be protected and kept in a safe place.
Chain of Custody Record
To establish the documentation necessary to trace sample possession from
the time of collection, a chain of custody record must be filled out and
accompany every sample. This record becomes especially important when the
sample is to be introduced as evidence in a court litigation. An example of
a chain of custody record is illustrated in Figure 8-3.
The record must contain the following minimum information:
Collector's sample number
Signature of collector
Date and time of collection
Place and address of collection
Waste type
Signatures of persons involved in the chain of possession
Inclusive dates of possession.
B-4
-------
Collector's Sample No.
CHAIN OF CUSTODY RECORD
Location of Sampling: Producer Hauler Disposal Site
Other:
Sample
Shipper Name: _____
Address: ___^ ^_^ _
numberstreetcTfystatezip
Collector's Name > Telephone: ( )
signature
Date Sampled Time Sampled hours
lype of Process Producing Waste
Field Information
Sample Receiver:
1.
name and address of organization receiving sample
2.
3.
Chain of Possession:
1. ___ . , .
signaturetitle inclusive dates
2.
signaturetitle Inclusive dates
3.
signaturetitle inclusive dates
Figure B-3. Example of chain of custody record (EPA 1982)
B-5
-------
Sample Analysis Request Sheet
The sample analysis request sheet (Figure B-4) is intended to accompany
the sample on delivery to the laboratory. The field portion of this form
must be completed by the person collecting the sample and should include most
of the pertinent information noted in the log book. The laboratory portion
of this form is intended to be completed by laboratory personnel and to
include at a minimum:
Name of person receiving the sample
Laboratory sample number
Date of sample receipt
Sample collection
Analyses to be performed.
Sample Delivery to the Laboratory
Preferably, the sample must be delivered in person to the laboratory for
analysis as soon as practicable—usually within 1 or 2 days after sampling.
The sample must be accompanied by the chain of custody record (Figure B-3)
and by a sample analysis request sheet (Figure B-4). The sample must be
delivered to the person in the laboratory authorized to receive samples
(often referred to as the sample custodian).
Shipping of Samples
All material identified in the DOT Hazardous Material Table (49 CFR
171.101) must be transported as prescribed in the table. All other hazardous
waste samples must be transported as follows:
1. Collect sample in an appropriately sized glass or poly-
ethylene container with non-metallic teflon-lined screw cap.
Allow sufficient ullage (approximately 10% by volume) so
container is not liquid full at 54°C Celsius (130°). If
sampling for volatile organic analysis, fill container to
septum but use closed cap with space to provide an air space
within the container. Large quantities, up to 3.785 liters
(1 gallon), may be collected if the sample's flash point is
equal to or greater than 23°C (73°F). In this case, the
flash point must be marked on the outside container (e.g.,
carton, cooler).
2. Seal sample and place in a 4 ml thick polyethylene bag, one
sample per bag.
3. Place sealed bag inside cushioned overpack. If sample is
expected to undergo change during shipment, cool using dry
or wet ice. Overpack must be designed to prevent water
leakage during transport. No other preservatives are
allowed.
4. Complete carrier's certification form.
B-6
-------
PART I: FIELD SECTION
SAMPLE ANALYSIS REQUEST
Collector
Date Sampled
Time
hours
Affiliation of Sampler
Address
number
Telephone ( )
LABORATORY
SAMPLE
NUMBER
street city
Company Contact
state
Tip"
COLLECTOR'S TYPE OF
SAMPLE NO. SAMPLE*
FIELD INFORMATION
Analysis Requested
Special Handling and/or Storage
PART II: LABORATORY SECTION**
Received by
Title
Analysis Required
Date
* Indicate whether sample is soil, sludge, etc.
** Use back of page for additional information relative to sample location
Figure B-4. Example of hazardous waste sample analysis
request sheet (EPA, 1982)
B-7
-------
5. Samples may be transported by rented or common carrier
truck, bus, railroad, and entities such as Federal Express*
but not by normal common carrier air transport even on a
"cargo only" aircraft.
Receipt and Logging of Sample
In the laboratory, a sample custodian should be assigned to receive the
samples. Upon receipt of a sample, the custodian should inspect the condi-
tion of the sample and the sample seal, reconcile the information on
the sample label and seal against that on the chain of custody record, assign
a laboratory number, log in the sample in the laboratory log book, and store
the sample in a secured sample storage room or cabinet until assigned to an
analyst for analysis.
The sample custodian should inspect the sample for any leakage from the
container. A leaky container containing multiphase sample should not be
accepted for analysis. This sample will no longer be a representative
sample. If the sample is contained in a plastic bottle and the walls show
the sample is under pressure or releasing gases, respectively, it should be
treated with caution. The sample can be explosive or release extremely
poisonous gases. The custodian should examine whether the sample seal is
intact or broken, since a broken seal may mean sample tampering and would
make analysis results inadmissible in court as evidence. Discrepancies
between the information on the sample label and seal and that on the chain of
custody record and the sample analysis request sheet should be resolved
before the sample is assigned for analysis. This effort might require
communication with the sample collector. Results of the inspection should be
noted on the sample analysis request sheet and on the laboratory sample log
book.
Incoming samples usually carry the inspector's or collector's identifi-
cation numbers. To further identify these samples, the laboratory should
assign its own identification numbers, which normally are given consecu-
tively. Each sample should be marked with the assigned laboratory number.
This number is correspondingly recorded on a laboratory sample log book along
with the information describing the sample. The sample information is copied
from the sample analysis request sheet and cross-checked against that on the
sample label.
Assignment of Sample for Analysis
In most cases, the laboratory supervisor assigns the sample for analy-
sis. The supervisor should review the information on the sample analysis
request sheet, which now includes inspection notes recorded by the laboratory
sample custodian. The supervisor should then decide what analyses are to be
performed. The sample may have to be split with other laboratories to obtain
the
*These procedures are designed to enable shipment by entities like Federal
Express; however, they should not be construed as an endorsement by EPA
of a particular commercial carrier.
B-8
-------
necessary information about the sample. The supervisor should decide on the
sample location and delineate the types of analyses to be performed on each
allocation. In his own laboratory, the supervisor should assign the sample
analysis to at least one analyst, who is to be responsible for the care and
custody of the sample once it is received. He should be prepared to testify
that the sample was in his possession or secured in the laboratory at all
times from the moment it was received from the custodian until the analyses
were performed.
The receiving analyst should record in the laboratory notebook the
identifying information about the sample, the date of receipt, and other
pertinent information. This record should also include the subsequent
testing data and calculations.
B-9
-------
APPENDIX C
Example Summary Sheets for
Analytical and Statistical Results
From Unsaturated Zone Monitoring
-------
EXAMPLE SUMMARY SHEETS FOR
ANALYTICAL STATISTICAL RESULTS
FROM UNSATURATED ZONE MONITORING
Appendix B provides chain of custody documentation and control to identify
and trace a sample from sample collection to final analysis. The documentation
includes sample labels, a detailed field log book, a chain of custody record, a
sample analysis request sheet, and shipping specifications.
This appendix provides example summary sheets for analytical and statisti-
cal results from unsaturated zone monitoring. Once the sample analysis is
completed, the analytical results for various background areas and uniform
areas (in the active portion) should be entered into summary tables, such as
the example tables illustrated. In addition, the results of the statistical
analysis should also be included in these tables. These tables should be
included in the operating record of the facility, along with the documentation
described above. It is essential that the data in these tables (e.g., sample
IDs) correspond to the detailed sampling information included in the field log
book. The field log book should, for example, clearly identify the location
and depth at which individual samples were taken.
The following example sheets should be reproduced to provide enough sheets
to tabulate data from several background areas or uniform areas, and many
sampling events. The example sheets may need to be modified to make them
applicable to given site-specific monitoring designs.
C-l
-------
GENERAL INFORMATION
EPA ID:
Company Name:
Address:
Person to contact about data:
Telephone Number: j[ }_
Location of Facility:
Number of Land Treatment Units at Facility:
If more than one identify each: #1
#2
#3
Uniform areas (in active portion) and corresponding background soil series in
each land treatment unit:
Uniform Area Background Soil Series
LTU#1
LTU#2
LTU#3
C-2
-------
BACKGROUND DATA
SOIL CORE MONITORING
Background Soil Series:
Corresponding Uniform Area(s) in Active Portion:
Current Date:
Initial Analysis
Reevaluation
(Check one) Date(s) of
Sampling:
Parameter (units)
p
Analytical Results
Sample
No. _
Sample
No. _
Sample
No. _
Sample
No. _
Statistical
Results
Mean
Var
Notes
Hazardous Constituents or Principle Hazardous Constituents (PHCs), and other
parameters measured (e.g., pH).
2Enter analytical results for each sample. Each sample is a composite from two
locations. Field log book must indicate where (location and depth) individual
samples were taken (on a site map) and how they were composited. Composite
sample no. shown in this table must correspond to the field log book (see
Appendix B).
C-3
-------
BACKGROUND DATA
SOIL PORE-LIQUID MONITORING
Background Soil Series:
Corresponding Uniform Area(s) in Active Portion:
Current Date:
Initial Analysis
Reevaluation
(Check one) Dates of
Sampling:
Parameter (units)
2
Analytical Results
of Quarterly Sampling
Sample
No. _
Sample
No. _
Sample
No. _
Sample
No. _
Statistical
Results
Mean
Var
Notes
1
Hazardous Constituents or Principle Hazardous Constituents, and any other
pertinent parameters.
"Each sample is a composite from two lysimeters. Field log book must indicate
where (location and depth) individual samples were taken and how they were
composited. Composite sample no. shown above in this table must correspond to
the field log book (see Appendix B).
C-4
-------
ACTIVE PORTION DATA
SOIL CORE MONITORING
Land Treatment Unit:
Uniform Area:
Corresponding Background Soil Series:
Current Date: Date(s) of Sampling:
Parameter (units)
Analytical Results2'3
Sample
No. _
Sample
No. _
Sample
No. _
Statistical
Results*
Mean
Var
Notes
Hazardous Constituents or Principle Hazardous Constituents (PHCs), and any
other pertinent parameters (e.g., soil pH).
2Each sample is a composite from two locations. Field log book must indicate
where (location and depth) individual samples were taken and how they were
composited. Composite sample no. shown above in this table must correspond to
the field log book (see Appendix B).
3If uniform area is greater than 5 ha., more than three composite samples are
necessary; therefore, table would have to be expanded in these cases.
4Circled parameter means that are found to be statistically signif. increased
over background.
C-5
-------
ACTIVE PORTION DATA
SOIL PORE-LIQUID MONITORING
Land Treatment Unit:
Uniform Area:
Corresponding Background Soil Series:
Current Date: Date(s) of Sampling:
Parameter (units)
Analytical Results2'3
Sample
No. _
Sample
No. _
Sample
No. _
Statistical
Results^
Mean
Var
Notes
Hazardous Constituents or Principle Hazardous Constituents (PHCs), and any
other pertinent parameters.
2
Each sample is a composite from two lysimeters. Field log book must indicate
where (location and depth) individual samples were taken and how they were
composited. Composite sample no. shown above in this table must correspond to
the field log book (see Appendix B).
3
If uniform area is greater than 5 ha., more than three composite samples
(i.e., from 6 lysimeters) are necessary; therefore, table would have to be
expanded in these cases.
4
Circled parameter means that are found to be statistically signif. increased
over background.
C-6
-------
APPENDIX D
Regulations on Unsaturated Zone Monitoring
Federal Register, Volume 47, Number 143
July 26, 1982
-------
PREAMBLE DISCUSSION ON UNSATURATED ZONE MONITORING
6. Unaaturated Zone Monitoring
(Section 284,278). As indicated earlier,
the purpose of unsaturated zone
monitoring ia to provide feedback on the
success of treatment in the treatment
zone. The information obtained from
this monitoring will be used to adjust
the operating conditions at the unit in
order to maximize degradation,
transformation and immobilization of
hazardous constituents in the treatment
zone.
For example, if a significant increase
of a hazardous constituent is detected in
unsaturated zone monitoring, the owner
or operator will examine more closely
the facility characteristics that
significantly affect the mobility and
persistence of that constituent These
significant facility characteristics may
include treatment zone characteristics
(e.g.. pH, cation exchange capacity,
organic matter content), or operational
practices [e.g., waste application method
and rate). Modifications to one or more
of these characteristics may be
necessary to maximize treatment of the
hazardous constituent within the
treatment zone and to minimize
additional migration of that constituent
to below the treatment zone.
It should be emphasized that
unsaturated zone monitoring is not a
substitute for ground-water monitoring.
Both are required at land treatment
units. Ground-water monitoring is
designed to determine the effect of
hazardous waste leachate on the ground
water. Unsaturated zone monitoring
cannot perform that function as a
general matter. Instead, unsaturated
zone monitoring simply gives an
indication of whether hazardous
constituents are migrating out of the
treatment zone.
Likewise, unsaturated zone
monitoring is not equivalent to the leak
detection monitoring that is used at
some other types of disposal units (e.g.,
double-lined surface impoundments).
Leak detection monitoring is used in
conjunction with a relatively "closed"
design (e.g., two liners with a drainage
layer between them) that is designed to
pick up any liquid migrating from the
unit EPA believes that such a design
can be a substitute for the ground-water
monitoring and response program of
Subpart F.
Unsaturated zone monitoring,
however, operates in an open system
that allows liquids to pass through the
unsaturated zone. While EPA believes
that unsaturated zone monitoring ia
generally reliable, it cannot provide the
same level of certainty about the-
migration of hazardous constituents
from the facility that a double-lined
surface impoundment (with a. leak
detection monitoring program) can
provide. Therefore, unsaturated zone
monitoring cannot be a substitute for
ground-water monitoring.
Some commenters have expressed
concern about the reliability and
practicality of unsaturated zone
monitoring, particularly soil-pore liquid
monitoring. EPA believes that adequate
technology and expertise is available to
develop effective and reliable systems.
The Agency also believes that the
inconvenience cited by some
commenters can be avoided.
Commenters stated that the placing of
lysimeters (one type of device for f
monitoring soil-pore liquid) on the active the PHCs
portion of a land treatment unit would
hinder site operations. However, the
Agency knows of a number of existing
land treatment units with monitoring
systems engineered so that the above-
ground portion of the device for
sampling soil-pore liquid is located off
the actual treatment zone. This and
other hazardous constituents are being
adequately treated.
The Regional Administrator may
address this situation by selecting
principal hazardous constituents (PHCs)
for the unit A PHC i* a hazardous
constituent contained in -the waste
applied at a unit that is difficult to
degrade, transform or immobilize ia die
treatment zone. Tha owner or operator
may ask the Regional Administrator to
establish PHCs at the unit if the owner
or operator can demonstrate to the
Regional Administrator's satisfaction
that degradation, transformation or
immobilization of the PHCs will assure
adequate treatment of the other
hazardous constituents in the waste.
The Regional Administrator will be
particularly concerned with two factors
when deciding whether to establish
PHCs. First he will be concerned with
the mobility of the constituent Since
PHCs will be monitored in the area
below the treatment zone, the Regional
Administrator will want to assure that
an early warning of the
failure of the treatment process.
Therefore, a PHC rtast be one of the
most mobile constituents in the
treatment zone. Second, a PHC must be
one of tha- most concentrated and
persistent constituents in the treatment
zone. This is to assure that the
the treatment zone.
In the selection of principal hazardous
constituents, the Regional Administrator
will evaluate the results of waste
, .. , , . , ., constituent provides a reliable
other methods can be used to avoid any mdication of the success of treatment in
inconvenience associated with the
location of these devices.
The unsaturated zone monitoring
program must be designed to determine
the presence of hazardous constituents , ... . . , ,
below the treatment zone. Generally this analyses, Uterature reviews laboratory
means that the owner or operator mnat tes.f ^ *f? »*Bdl«»- Wafte ^^^
monitor for the hazardous constituents ™* * U8fld to ldentify *" hazardous
identified for each hazardous waste that
is placed in> or on the treatment zone.
EPA believes, however, that there
may be some situations where this
general monitoring burden may be
reduced without compromising the
objectives of the unsaturated zone
monitoring program. Some hazardous.
constituents will be more difficult to
degrade, transform or immobilize than
others* Therefore, if the owner or
operator monitors for-the constituents
that are difficult to treat and can
demonstrate that such constituents are
not migrating from the treatment zone,
obtained from literature reviews,
laboratory tests, and field studies
(including monitoring results for existing
units) will be used to assess the relative
mobility and persistence of the various
hazardous constituents. The extent of
data needed to support the selection of
one or more principal hazardous
constituents fora particular waste will
be determined by the Regional
Administrator.
Both soil-core and soil-pore liquid
monitoring are required in today's rules.
These two monitoring procedures are
then EPA can be reasonably certain that intended to complement one another.
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Soil-core monitoring will provide
information primarily on the movement
of "slower-moving" hazardous
constituents (such as heavy metals).
whereas soil-pore liquid monitoring wifl
provide essential additional data on the
movement of fast-moving, highly soluble
hazardous constituents that soil-core
monitoring may miss.
The general elements of *h°
unsaturated zone monitoring program
are patterned after those required for
ground-water monitoring in Subpart F.
As in the detection monitoring program.
the unsaturated zone monitoring
program is designed to determine
whether the level of hazardous
constituents in the soil or soil-pore
liquid below the treament zone shows
statistically myiifimnt increases over
the background levels of those
constituents in the soil or soil-pore
liquid. In addition, today's regulations
include requirements for monitoring
systems, sampling frequency anH
sampling «"«i analysis pr
methods that are analogous to those in
Subpart F. Some modifications of the
Subpart F monitoring program must be
made, however, to make it compatible
with land treatment
First, the basis for establishing
background values differs. In the
ground-water monitoring program.
background values are based on data
taken from upgradient monitoring wells.
Such a concept is not applicable to land
treatment units. Background values at
land treatment units are established by
sampling the soil and soil-pore liquid in
a. background plot A background plot is
generally a segment of the soil near the
unit that has characteristics similar to
that of the treatment zone and that has
not been contaminated by hazardous
waste. At a new unit however, the
owner or operator could use the actual
treatment zone prior to waste
application as the background plot The
key characteristic of the background
plot is its similarity to the treatment
zone.
Second, the unsaturated zone
monitoring program will rely on
statistical procedures that are somewhat
different than those used for detection
monitoring programs under Subpart F. In
order to account for seasonal variations
in soil-pore liquid quality, background
values will be baaed on one year of
quarterly sampling as hi the detection
monitoring program. Since background
soil levels are not likely to change
significantly during such a time frame,
today's rules allow that background soil
levels may be established following a
one-time sampling. Unsaturated zone
monitoring is similar to compliance
monitoring, however, in that there may
be several constituents to be monitored.
Thus, the probability of an experiment
error rate is h'gh Therefore, the
statistical procedures used in the
unsaturated zone monitoring program
will be based on a narrative standard'as
used in the compliance monitoring
program.
This standard seeks to provide
"reasonable confidence" that the
migration of hazardous constituents
from the treatment zone will be
indicated after balancing the risk of
false positives and the risk of false
negatives. (This preamble discusses the
rationale for this standard in Section
VILD.ia.) If the number of constituents
to be monitored is small, then this
standard can be met by the use of the
Student's t-test protocol described in
While EPA believes that the standard
for statistical procedures just described
should-be adequate for most situations.
EPA intends to farther analyze the
appropriateness of other statistical
procedures for unsaturated zone
monitoring. For example, EPA is
considering whether other factors that
might affect background levels of soil
pore-water quality should be
specifically addressed in devising the
monitoring protocols. EPA specifically
asks for public comment on this issue.
Third, the unsaturated zone
monitoring program does not call for
measurements of the flow and direction
of ground water. The gradient hi the
ground water is not relevant to
unsaturated zone monitoring and, thus,
such information is not necessary.
Fourth, the response to the detection
of a statistically significant increase in
Subpart M differs from the response
required in Subpart F. The results of
unsaturated zone monitoring are to be
used in the modification of the operating
practices at the unit Thus, the required
response is the submission, within 90
days, of a permit modification
application that sett forth how the
owner or operator will adjust his
operating practices (including waste
application rates) to maximize
degradation, transformation and
immobilization of hazardous
constituents in the treatment zone.
However, an opportunity exists in
today's rules for not submitting the
permit modification application, but
only if the owner or operator can
successfully demonstrate to the
Regional Administrator that the
statistically significant increase results
from an error in sampling, analysis, or
evaluation. This error demonstration
must be submitted to the Regional
Administrator within 90 days of the
owner or operator's knowledge of the
statistically significant increase.
As indicated earlier in this preamble,
the appearance of hazardous
constituents below the treatment zone
does not in itself constitute a violation
of the regulations. (This is analogous to
the fact that a landfill liner which has
been designed not to leak does not
violate the design standards if the liner
fails at some future time*.) Under the
regulatory strategy in these regulations,
contaminants that are not controlled by
the design and operating measures will
be addressed by the monitoring and
response program in Subpart F.
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REGULATIONS ON UNSATURATED ZONE MONITORING
§264£7t Unsaturatad zone monitoring.
An owner or operator subject to this
subpart must establish, an unsaiurated
zone monitoring program to discharge
the following responsibilities;
(a) The owner, or operator must
monitor the soil and soil-pore liquid to
determine whether hazardous
constituents migrate out of the treatment
zone.
(1) The Regional Administrator will
specify the hazardous constituents to be
monitored in the facility permit. The
hazardous-constituents to be monitored
are those specified under 5 2&i271(b)r-
(2) The Regional Administrator may
require monitoring for prtnripal
hazardous constituents (PHCs] in lieu of
the constituents specified under
$ 264.271(b). PHCs-are hazardous
constituents contained in the wastes to
be applied at the unit that are the most
difficult to treat considering the
combined effects of degradation,
transformation, and immobilization. The
Regional Administrator-will establish
PHCs ifhe finds, based on waste
analyses, treatment c'emonstrations, or
other data, that effective degradation.
PHCs will assure treatment at at least
equivalent levels for the other
hazardous constituents in the wastes.
(b) The owner or operator most install
an unsaturated zoos monitoring system
that includes soil monitoring using .soil
cores and soil-pore liquid monitoring
using devices such as lysHuetets. The
unsaturated zone monitoring system
must consist of a sufficient number of
sampling points at appropriate location*
and depths to yield samples that:
(1) Represent the quality of
background soil-pare liquid quality and
the chemical make-up of soil that has
not been -affected Tiy leakage from the
treatment zone; and
(2) Indicate the quafity of sod-pore
liquid and the'chenitcal make-up of the
soil below the treatment zone.
(c) The owner or operator mast
establish a background -vafcie foe each
hazardous constituent-to b* monitored
under paragraph- (a) of this section. The
permit will specify the background
values for each constituent or specify
the procedures to ba usad to calculate
tlX6
(1) Background wd values may be
based on a one-time sampling at a
background plot having characteristics
similar to those of the treatment zone.
(2) Background soil-pore liquid values
must be based on at least quarterly
sampling for one year at a background
plot having characteristics similar to
those of the treatment *""»,
(3) The owner or operator must
express all background values in a form
necessary for the soil-pore
liquid.monitoring immediately below the
treatment .zone. The Regional
Administrator will specify the frequency
and timing of soil and soil-pore liquid
monitoring in the facility permit aitsr
considering the frequency, timing and
rate of "waste application. anA the soil
permeability. The owner or operator
must eJLjjieaj the results of soil and soil-
pore liquid monitoring in a form
necessary for the determination of
statistically significant increases under
paragraph (f) of this section.
(e) Tha owner or operator must use
consistent sampling and -analysis
procedures that are designed to ensure
sampling results that provide a reliable
indication of sod-pore liquid quality and
tha chemical make-up of the soil below
the irea&nant juiue. At a minimum, the
owner or operator-most implement
procudu«is aad.tecmaques for
(1) Sample collection:
(2) SaaRjle preservation and shipment;
(3) Analytical procedures; and
(11 la dBtmuiHiiig whether a
statistically significant increase has
occurred, the owner-or opezator^nust
compare the value of
(4)
(f) *p"*
"T^1 ** l"r
determine whether mom is a
constituent to bamoniiaced under
paragraph (a) afthissanttoB below the
treatment zone each time he conducts
soil Mntaring aad mil-pan liquid
monitoring under paragraph (d) of this
sectiaa.
as determined under paragraph (d) of
this section, to the background value for
that constituent according to the
statistical procedure specified in the
facility permit under this paragraph.
(2) The owner or operator must
determine whether there has been a .
statistically significant increase below
the treatment zone within a reasonable
time period after completion of
sampling. The Regional Administrator
will specify that time period in the
facility permit after considering the
complexity of the statistical test and the
availability of laboratory facilities to
perform the analysis of soil and soil-
pore liquid samples.
(3) The' owner or operator must
determine whether there is a
statistically significant increase below
the Tsatment zone using a statistical
procedure that provides reasonable
confidence tost msgrataon irom the
treatment zone wiU be identified. Tha
Regional Administrator will specify a
statistical procedure in the facility
permit that he finds:
(i) Is appropriate for the distribution
of the data used to establish background
values; and
(ii) Provides a reasonable balance
between the probability of falsely
identifying migration from the- treatment
zone and the probability of failing to
identify real migration from the
treatment zone.
(g) If the owner or operator
determines, pursuant to paragraph (f) af
this section, that there is a statistically
significant increase of hazardous
constituents below the treatment zone,
he must:
(1) Notify the Regional Administrator
of this finding in writing within seven
days. TJw notification must indicate
what constituents have shown
statistically significant increase*.
(2) Within 98 days, -3000111 to tha
Regional Administrator aa appiieattea
for a permit modification to modify the
operating practices at the facility in
order to maximize the success af
degradation, transformeaoa. or
D-3
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immobilization processes in the
treatment zone.
(h) If the owner or operator
determine*, pursuant to paragraph (f) of
this section, that then is a statistically
B trf ^laB*'
constituents beiow the treatment zone.
he may demonstrate that a source other
than regulated mriis caused the increase
or that the increase resulted from an
error in sanpting. analysis, or
evaluation. While the owner or operator
may males a demonstration under this
paragraph in addition to, .or in lieu of,
submitting a permit modification
appScatioB under paragraph (g}{2) of
this section, he is oat relieved of the
requirement to submit a permit
modification application within the time
specified in paragraph (g)(2) of this
section unless the demonstration made
under this paragraph successfully shows
that a source other than regulated units
caused the increase or that the increase
resulted from an error in sampling,
analysis, or evaluation. In making a
demonstration under this paragraph, the
owner or operator must
(1} Notify the Regional Administrator
in writing within seven days of
determining a statistically significant
increase below the treatment zone that
he intends to make a determination
under this paragraph:
(2) Within 90 days, submit a report to
the Regional Administrator
demonstrating that a source other than
the regulated units caused the increase
or that the increase resulted from error
in sampling, analysis, or evaluation;
(3j Within 90 days, submit to the
Regional Administrator an application
for a permit modification to make any
appropriate changes to the unsaturated
zcr.3 .T.oniiorisg program at the facility;
and
(4) Continue to monitor in accordance
with the unsaturated zone monitoring
program established under this section.
*U.S. GOVERNMENT PRINTING OFFICE! 1985-&61-221/24030
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