&EPA
United States
Environmental Protection
Agency
Office of Solid Waste and
Emergency Response
Washington DC 20460
Environmental Monitoring
Systems Laboratory
Las Vegas NV89114
Solid Waste
EPA/530-SW-86-040
Permit Guidance
Manual on
Unsaturated Zone
Monitoring for
Hazardous Waste
Land Treatment Units
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EPA/530-SW-86-040
October 1986
PERMIT GUIDANCE MANUAL ON UNSATURATED ZONE MONITORING
FOR HAZARDOUS WASTE LAND TREATMENT UNITS
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Las Vegas, Nevada
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
Washington, D.C. 20460
U.S. Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12th ftov
Chicago. IL 60604-3590
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NOTICE
This manual is considered the final version of EPA's guidance on unsaturated
zone monitoring at hazardous waste land treatment facilities. It is intended to
be used by permit applicants and permit writers as an aid to comply with RCRA
Subtitle C monitoring regulations for hazardous waste land treatment units. This
guidance is not intended to mean that other designs and equipment might not also
satisfy the regulatory standards. This manual has undergone extensive public
review and this final version reflects and incorporates the comments received
which include coments from both major universities and oil companies. This
manual is intended to be a technical aid. It is not intended to present official
policy or supersede any regulations relevant to unsaturated zone monitoring at
hazardous waste land treatment facilities. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.
ii
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PREFACE
This 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.
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 throuqh 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 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.
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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 (^[264.278) 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.
iv
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TABLE OF CONTENTS
Page
PREFACE [[[ I"'
EXECUTIVE SUMMARY [[[ iv
LIST OF FIGURES [[[ viii
LIST OF TABLES [[[ *i
ACKNOWLEDGMENTS
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 .............................. 6
2.3 Capillary Fringe ........................................... 6
2.4 Flow Regimes ............................................... 8
2.4.1 Darcian Flow ........................................ 9
2.4.2 Macropore Flow ...................................... 9
3.0 SOIL-CORE MONITORING ............................................ 11
3.1 General Equipment Classification ........................... 11
3.1.1 Sampling with Multipurpose Drill Rigs ............... 11
3.1.1.1 Multipurpose Auger-Core-Rotary
Drill Rigs ................................. 11
3.1.1.2 Auger Drills ............................... 11
3.1.1.3 Hollow-Stem Auger Drilling and Sampling ____ 12
3.1.1.4 Continuous Flight Auger Drilling
and Sampling ............................... 12
3.1.1.5 Cylindrical Soil Samplers .................. 12
3.1.1.5.1 Thin Walled Volumetric Samplers . 12
3.1.1.5.2 Split-Barrel Drive Samplers ..... 19
3.1.1.5.3 Continuous Sample Tube System ... 19
3.1.1.5.4 Peat Sampler .................... 19
3.1.2 Hand-Operated Drilling and Sampling Devices ........ 19
3.1.2.1 Screw-Type Augers ......................... 21
3.1.2.2 Barrel Augers ............................. 21
3.1.2.3 Post-Hole Augers .......................... 21
3.1.2.4 Dutch-Type Auger .......................... 25
3.1.2.5 Regular or General Purpose Barrel Auger ... 25
3.1.2.6 Sand Augers ............................... 25
3.1.2.7 Mud Augers ................................ 25
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TABLE OF CONTENTS
(continued)
3.2 Criteria For Selecting Soil Samplers 30
3.2.1 Capability for Obtaining Various Sample Types 32
3.2.2 Sampling Various Soil Types 32
3.2.3 Site Accessibility and Trafficability 32
3.2.4 Relative Sample Size 34
3.2.5 Personnel Requirements 34
3.3 Random Soil-Core Monitoring Site Selection 34
3.4 Sample Number, Size, Frequency and Depths 37
3.4.1 Compositing Samples 40
3.4.1.1 Compositing with a Mixing Cloth 40
3.4.1.2 Compositing with a Mixing Bowl 41
3.5 Sampling Procedure 40
3.5.1 Preliminary Activities 40
3.5.2 Sample Collection With Multipurpose Drill Rigs 43
3.5.2.1 Hollow-Stem Auger Drilling and Sampling 43
3.5.2.2 Continuous Flight Auger Drilling and
Sampling 44
3.5.2.3 Samplers 45
3.5.2.3.1 Thin-Walled Volumetric Tube
Sampl ers 46
3.5.2.3.2 Piston Samplers 47
3.5.2.3.3 Split Barrel Drive Samplers 47
3.5.2.3.4 Continuous Sample Tube Systems .. 47
3.5.2.3.5 Peat Sampler 50
3.5.3 Sample Collection with Hand-Operated Equipment 51
3.5.3.1 Screw-Type Augers 51
3.5.3.2 Barrel Augers 51
3.5.3.3 Tube-Type Samplers: Soil Probe 52
3.5.3.4 Tube Type Samplers: Veihmeyer Tubes 54
3.5.4 Miscellaneous Tools 57
3.6 Decontamination 57
3.6.1 Laboratory Cleanup of Sample Containers 57
3.6.2 Field Decontamination 57
3.7 Safety Precautions 58
3.8 Data Analysis and Evaluation 59
4.0 SOIL-PORE LIQUID MONITORING 63
4.1 Soil Moisture/Tension Relationships 65
4.2 Pore-Liquid Sampling Equipment 67
4.2.1 Ceramic-Type Samplers 67
4.2.2 Cellulose-Acetate Hollow Fiber Samplers 73
4.2.3 Membrane Filter Samplers 73
4.2.4 Pan Lysimeters 76
4.3 Criteria for Selecting Soil-Pore Liquid Samplers 76
4.3.1 Preparation of the Samplers 80
4.4 Random Pore-Liquid Monitoring Site Selection 80
4.4.1 Surveying in the Locations of Sites and
Site Designations 83
vi
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TABLE OF CONTENTS
(continued)
Page
4.5 Sample Number, Size, Frequency and Depths 83
4.6 Installation Procedures for Vacuum-Pressure
Pore-Liquid Samplers 87
4.6.1 Constructing Trenches and Instrument
Shel ters 87
4.6.2 Installing Access Lines 89
4.6.3 Step-by-Step Procedures for Installing
Vacuum-Pressure, Pore-Liquid Samplers 92
4.6.3.1 Constructing the Hole 92
4.6.3.2 Sampler Installation Procedure 92
4.6.3.3 Bentonite Clay Method 94
4.6.3.4 Backfilling the Trench and Final Survey 94
4.7 Operation of Vacuum-Pressure Sampling Units 96
4.7.1 Porous Segments in Lysimeters 98
4.7.2 Dead Space in Lysimeters 101
4.8 Special Problems and Safety Precautions 103
4.8.1 Hydraulic Factors 103
4.8.2 Physical Properties: Soil Texture and
Soil Structure 103
4.8.3 Cup-Wastewater Interactions 104
4.8.3.1 Plugging 104
4.8.3.2 Change in the Composition of Hazardous
Constituents During Movement Through
Pore-Liquid Samplers 105
4.8.4 Climatic Factors 105
4.8.5 Safety Precautions 106
4.8.6 Lysimeter Failure Confirmation 106
4.9 Pan Lysimeter Installation and Operation 107
4.9.1 Trench Lysimeters 107
4.9.2 Free Drainage Glass Block Samplers 110
4.10 Pan Lysimeter Limitations Ill
4.11 Data Analysis and Evaluation Ill
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 Analytical Statistical
Results From Unsaturated Zone Monitoring C-l
APPENDIX D: Regulations on Unsaturated Zone Monitoring D-l
vn
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LIST OF FIGURES
Number
2-1
2-2
3-1
3-2
3-3
3-4
3-5
3-6A
3-6B
3-7
3-8
3-9
3-10
3-11
3-12
3-13
3-14
3-15
3-16
3-17
3-18
3-19
Diagrammatic Land Treatment Cross Section
i n the Vadose Zone ,
Cross Section Through the Unsaturated Zone
(Vadose Zone) and Groundwater Zone ,
Hollow-Stem Auger Drilling Tools ,
Drilling and Sampling with Hollow-Stem Augers ,
Continuous Flight Auger Drilling ,
Continuous Flight Auger Drilling Through
Coring Material ,
Thin-Walled (Shelby Tube) Sampler
Shelby Tube With Acetal Plastic Soil Seal Inserted ,
Trimming Tool, Applicator Rod, and Seals With
Cut-Away View of Soil Seal in Place
Continuous Sample Tube System
Screw-Type Auger/Spi ral Auger
Regular Auger
Post-Hole Type of Barrel Auger
Dutch Auger
Sand Auger
Mud Auger
Soi 1 Sampl i ng Tube
Vei hmeyer Tube
Random Site Selection Example for Unit cc
Soil Core Sampling Depths
Core Sample Extruding Device
Soil Core Retainers for Sampling in Very Wet Soils
and Cohensionless Soils
Page
5
7
13
14
15
16
17
18
18
20
22
23
24
26
27
28
29
31
35
39
48
49
VI 11
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LIST OF FIGURES
(continued)
Number
3-20
3-21
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
4-10
4-11
4-12
4-13
4-14
4-15
4-16
4-17
4-18
Barrel Auger Sampl i ng Method
Operation of "Backsaver" Handle with Soil Sampling Tube
Variation of Porosity, Specific Yield, and Specific
Retention with Grain Size
Moisture Retention Curves - Three Soil Types
Soi 1 -water Sampl er
Vacuum-pressure Sampler
Modified Pressure-vacuum Lysimeter
"Hi/Pressure-vacuum Soil -water Sampler"
Facilities for Sampling Irrigation Return Flow Via
Filter Candles, for Research Project at Tacna, Arizona
Membrane Fi 1 ter Sampl er
Example of a Pan Lysimeter
Free Drainage Glass Block Sampler
Sketch of Land Treatment Site Showing Designations at
Pore-Liquid Sampling Sites
Pore Liquid Sampling Depths
Location of Suction Lysimeters
Views of Trench and Access Shafts at Pore-Liquid
Sampler Sites on Active Land Treatment Site
Above Ground Shelter for Sample Bottles and
Accessories (Side View)
Burial Shelter for Sample Bottle and Accessories
Installation of Access Tubes in a Pressure-Vacuum
Pore-Liquid Sampler
Bentonite Clay Method of Installing Vacuum-Pressure
Pore-Liquid Samplers
Page
53
55
64
66
68
70
71
72
74
75
77
78
84
85
86
88
90
91
93
95
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LIST OF FIGURES
(continued)
Number Page
4-19 Stages in the Collection of a Pore-Liquid Sample
Using a Vacuum-Pressure Sampler 97
4-20 Diagrammatic View of Lysimeter Cup Wall 100
4-21 Location of Potential Dead Space in Suction Lysimeters 102
4-22 Trench Lysimeters Installed in Trench Shelter 108
4-23 Pan Lysimeter Installation 109
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LIST OF TABLES
Number Page
3-1 Criteria for Selecting Soil Sampling Equipment 33
3-2 Summary of Soil-Core Sampling Protocol for Background
and Acti ve Land Treatment Areas 38
3-3 Example Checklist of Materials and Supplies 42
3-4 Personnel Protective Equipment 60
4-1 Summary of Guidance on Pore-Liquid Sampling 81
XI
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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 Officers were
L.G. McMillion and L.A. Eccles, Environmental Monitoring Systems Laboratory,
Las Vegas, Nevada. Subsequent to the completion of the manual, the responsi-
bility for completion of this manual was shifted to the Office of Solid Waste,
under the direction of Mr. Michael Flynn and Mr. Jon Perry in Washington, D.C.
Both Mr. Eccles and Mr. Perry played an active role in the manual's final
preparation.
Dr. Charles 0. Riggs of the Central Mine Equipment Company provided an
extensive review of the soil core sampling protocols. Several excellent
recommendations were made relative to soil core sampling.
Earlier drafts of this manual were distributed to the EPA regional offices
for review and comment (6/83) and presented in the Federal Register for nation-
al comment and review (12/84). 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.
xn
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SECTION 1
INTRODUCTION
The purpose of this document is to provide guidance on essential elements
of an unsaturated zone monitoring program and to assist individuals in develop-
ing and evaluating these programs. The scope of this document covers unsatura-
ted 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 require-
ments (§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 equipment
are highlighted. Sampling protocols, including sampling design, frequency,
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 disposing
of some types of hazardous wastes. Land treatment involves the application 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 unsaturated zone
monitoring program must include procedures to detect both slow moving hazardous
constituents as well as rapidly moving hazardous constituents. 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 moni-
toring 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 appara-
tus are presented. The field implementation and operating requirements for
each piece of equipment is presented in a step-by-step format. Sample collec-
tion, preservation, storage, 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. 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, refer-
red hereafter as "principal hazardous constituents (PHCs)," 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 Waste 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 manage-
ment of land treatment units. Test Methods for Evaluating Solid Waste (SW-846)
(EPA, 1982b) provides procedures that may be used to evaluate the character!s-
tics 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) identi-
fies specific designs and operational procedures that EPA believes accomplish
the performance requirements in RCRA Sections 264.272 (treatment demonstra-
tion), 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
Haste Sites (Everett et al., 1983) describes the applicability of vadose zone
monitoring techniques to hazardous waste site investigations. Physical, chemi-
cal, geologic, topographic, geohydrologic, and climatic constraints for vadose
zone monitoring are described. Vadose zone monitoring techniques are categor-
ized 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 information. In
addition to the soil survey reports, each county office usually has aerial
photographs that provide general information on the soils in a particular 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 agricultural
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 information
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 saturated
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 regulations.
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 (Figure 2-1).
2.1 SOIL ZONE
The surface soil zone is generally recognized as that region that mani-
fests the effects of weathering of native geological material. The movement of
water in the soil zone occurs mainly as unsaturated flow caused by infiltra-
tion, percolation, redistribution, and evaporation (Klute, 1965). In some
soils, primarily those containing horizons of low permeability, such as heavy
clays, 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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en
Water
Vapor
and C02
Volatile
and Gaseous
Emissions
Precipitation
Zone of
Incorporation
(0.5-1 Ft)
Treatment
Zone
(up to 5-Ft)
Run-on and
Wastes Uniformly Applied Run-off are
and Incorporatedin the Soil ControMed
VADOSE
ZONE
TvT.T'- o7'. v"y-." ; ;r-V'-?y r^Vo.'. Percolation'of .' °- -.'"'-^''. 'T'VYjVlative 591!'" °'-. '>
^:v;iv',;-.:-;«;v;?.V-:^/^:-;^;..-.SpiiWater - :v/.:-.v.-. j-.^i.-'.-ivv-v---?--1-V'.:-
. - e .'.'-.'r «..'..''."'"n "01: '''. o.t -i .»..'»» ».!
v.» '-« .' !.<>.'..' " ' i-.« « '- '- ' ' o- - *.° .'.-.* .'.P..''. °. ' . » .. '.°' ...'.".. - . .
ZONE OF
AERATION
\\\\\\\\\\\\
CAPILLARY FRINGE
i_~i_-rLrz_~i_~i_"i_~z_~i-~ GROUNDWATEROR -__-__r~_j-_rz-.~Lr--T.
-SATURATED ZONE
Figure 2-1. Diagrammatic land treatment cross section in the vadose zone
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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 unsat-
urated 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 2-2 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 inter-
mediate 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 percolation 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 down-
ward 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 hydraulic
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 permeabil-
ity overlies a region of lower permeability in the unsaturated 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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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 constant.
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 chemi-
cal-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 observa-
tions, 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 signifi-
cant in the regions underlying the soil. They recommend that investigations 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." Monitor-
ing in the intermediate zone and capillary fringe will require the extension 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 land-
fill. 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 unsat-
urated 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 move-
ment of fast-moving, highly soluble hazardous constituents.
Current literature on soil water movement in the unsaturated zone des-
cribes 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 classical concept of
-------
infiltration depicts a distinct, somewhat uniform, wetting front slowly advan-
cing 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 i£ (2-1)
More generally, the velocity
|/ dh (?.?\
K dT 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 assumes one-dimensional, steady state conditions and is
applicable only within the laminar range of flow where resistive forces
govern flow. As velocities increase, inertia! forces, and ultimately turbu-
lent flows, cause deviations from the linear relation of Eq. (2-2). Fortun-
ately, for most natural groundwater motion, Darcy's law can be applied in the
equation of continuity.
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 one
would expect if flow was evenly distributed. It is important to note that
this secondary porosity is made up of continuous fractures or fissures and
should not be confused with flow through large porous media. 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 concept of field capacity, however, is not relevant to this
type of flow regime. The depth of macropore flow penetration is a function
of initial water content, the intensity and duration 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 cylindrical (Thomas and
Phillips, 1979). Exemplifying the role of macropores, Bouma et al. (1979)
reported that planar pores with an effective width of 90 ym 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 macro-
pores and result in only partial displacement or dispersion 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
radial 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 the same time
that is predictable by Darcian theory.
The occurrence of macropore flow poses serious implications for unsatura-
ted zone monitoring and the protection of groundwater from the land treatment
of hazardous wastes. The first implication is that contaminated water will
flow rapidly through the treatment zone and not receive full treatment. Under
this short circuit scenario groundwater contamination is probable.
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 representative
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 sampling devices and systems for unsaturated zone sampling are
divided into two general groups, namely: (1) those samplers used in conjunc-
tion with multipurpose or auger drill rigs and (2) those samplers used in
conjunction with hand-operated drilling devices. In most cases, the hand-
operated drilling device is also the sampler.
3.1.1 Sampling with Multipurpose Drill Rigs
For most circumstances the use of hollow-stem augers with some type of
cylindrical sampler will provide a greater level of assurance that the soil
being sampled within the unsaturated soil zone was not carried downward by the
hole excavating or sampling process. For some situations, such as sampling
dense to very dense or stiff to very hard ground, the use of multipurpose
auger-core-rotary drills will be necessary. For some geologic circumstances
the use of continuous flight augers will provide an adequate drilling method.
3.1.1.1 Multipurpose Auger-Core-Rotary Drill Rigs--
Multipurpose auger-core-rotary drill rigs are generally manufactured with
rotary power and vertical feed control to advance both hollow-stem augers and
continuous flight (solid-stem) augers to depths greater than 100 ft (30 m).
These same drills have secondary capability for rotary and core drilling. The
larger of these drills have 90 to 130 HP power sources and are typically
mounted on 20,000 to 30,000 Ib GVW trucks. The same multipurpose drill rigs
are readily available in North America on both rubber-tired and track-driven
all-terrain carriers. The smaller of the multipurpose drills have 40 to 60 HP
power sources and are typically mounted on trailers or one-ton, 4x4 trucks.
3.1.1.2 Auger Drills--
Auger drill rigs are similar to multipurpose auger-core-rotary drill rigs.
They are manufactured specifically for efficient auger drilling but do not have
the pumps and hoists that are required for efficient core or rotary drilling.
There are relatively few auger drills available in comparison to multipurpose
auger-core-rotary drills.
11
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3.1.1.3 Hollow-Stem Auger Drilling and Sampling
The tools used for hollow-stem auger drilling (Figure 3-1) consist of
outer components: hollow auger sections, hollow auger head and drive cap, and
inner components: pilot assembly, center rod column and rod-to-cap adaptor.
Auger sections are typically 5 ft in length and are interchangeable for assem-
bly in an articulated but continuously flighted column. Drilling progresses in
5 ft or shorter increments. Sampling can be accomplished at any depth within a
5 ft drilling increment. On completion of a 5 ft (1.5 m) increment of drill-
ing, another 5 ft section of hollow auger and center rod is added. Hollow-stem
augers are manufactured and are readily available with inside diameters of 2.25
in., 2.75 in., 3.25 in., 3.75 in., 4.25 in., 6.25 in. and 8.25 in. In general,
sampling is accomplished by removing the pilot assembly and center rod and
inserting the sampler through the hollow axis of the auger (Figure 3-2).
3.1.1.4 Continuous Flight Auger Drilling and Sampling
When continuous flight (solid-stem) augers are used for sampling, the
complete articulated column of 5 ft sections must be removed from the borehole
(Figure 3-3). This method can provide an adequately clean borehole in some
fine grained soils. When the continuous flight auger method is used in caving
or squeezing ground (Figure 3-4), the quality of sample and the origin of the
recovered sample is questionable.
3.1.1.5 Cylindrical Soil Samplers
Cylindrical samplers are either pushed or driven in sequence with an
increment of drilling or advanced simultaneously with the advance of a hollow
auger column.
3.1.1.5.1 Thin walled volumetric samplersThin wall volumetric (Shelby tube)
samplers (Figure 3-5) are readily available in 2 in., 3in. and 5 in. OD and are
commonly 30 in. in length. The 3 in. OD x 30 in. length sampler is most
common. During the manufacturing process, the advancing end of the sampler is
rolled inwardly and machined to a cutting edge that is usually smaller in
diameter than the tube ID. The cutting edge ID reduction, defined as a
"clearance ratio", is usually in the range of 0.0050 to 0.0150 or 0.50% to
1.50% (Refer to ASTM D1587).
When Shelby tubes are pushed into soil, the sample recovered is often less
than the distance pushed, i.e., the recovery ratio is less than 1.0. The
recovery ratio is usually less than one because the friction between the soil
and the tube ID becomes greater than the shear strength of the soil in front of
the tube; consequently, soil in front of the advancing end of the tube is
displaced laterally rather than entering the tube (See Hvorslev 1949). The
sampler tube is usually connected with set screws to a sampler head which in
turn is threaded to connect with standard drill rods. The sampler head usually
has a ball check valve for sampling below the water level.
Plastic sealing caps (Figures 3-6A and 3-6B) and other soil sealing
devices are readily available for the 2-, 3- and 5-inch diameter tubes. Shelby
tubes are commonly available in carbon steel but can be manufactured from other
metal tubing.
12
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Drive Cap
Auger Head
Center Head
Rod it) Cap
Adapter
Auger Connector
Hollow Stem
Auger section
Center Rod
Pilot Assembly
Auger Connector
Replaceable Carbide
insert Auger Tooth
Figure 3-1. Hollow-stem auger drilling tools
(Courtesy Central Mine Equiment Co.)
13
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Figure 3-2. Drilling and sampling with hollow-stem augers
(Courtesy Central Mine Equipment Co.)
14
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GROUND
4 INCH
CONTINUOUS FUKSHT
Figure 3-4. Continuous flight auger drilling through coring material
(Courtesy Central Mine Equipment Co.)
16
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HC AO. MOOU SECTION 7 , UhLVE. RUBBER 4UT
,rfJG. TOP SECTION/' SCfltH
. HCAa BOTTOM SECTION
VMU. TU6C
Figure 3-5. Thin-walled (shelby tube) sampler
17
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Figure 3-6A.
Shelby tube with acetal plastic soil seal inserted
(Courtesy Acker Drill Company, Inc.)
Figure 3-6B.
Trimming tool, applicator rod, and seals with
cut-away view of soil seal in place
(Courtesy Acker Drill Company, Inc.)
18
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3.1.1.5.2 Split-barrel drive samplersA split-barrel drive sampler consists
of two split-barrel halves, a drive shoe and a sampler head containing a ball
check valve, all of which are threaded together for the sampler assembly. The
most common size has a ?. in. OD and a 1.5 in. ID split barrel with a 1.375 in.
ID drive shoe. This sampler is used extensively in geotechnical exploration
(Refer to ASTM D1586). When fitted with a 16 gage liner, the sampler has a
1.375 in. ID throughout. A 3 in. OD x 2.5 in. ID split-barrel sampler with a
2.375 in. ID drive shoe is commonly available. Other split-barrel samplers in
the size range of 2.5 in. OD to 4.5 in. OD are manufactured but are less
common.
3.1.1.5.3 Continuous sample tube systemContinuous sample tube systems that
fit within a hollow-stem auger column (Figure 3-7) are manufactured and readily
available in North America. These sample barrels are typically 5 ft in length,
fit within the lead auger of the hollow auger column and for many ground
conditions provide a continuous, 5 ft sample. The soil sample enters the
sampling barrel as the hollow auger column is advanced. The barrel can be
"split" or "solid" and can be used with or without liners of various metallic
and non-metallic materials. Clear "plastic" liners are often used. Usually
two 30-inch liner sections are used.
3.1.1.5.4 Peat samplerAt some sites, the soils may contain sufficient
organics such that a peat sampler may provide an adequate sample. This sampler
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 collec-
ted sample. According to Acker (1974), the sample removed is 3/4 inch diameter
and 5? inches in length.
3.1.2 Hand-Operated Drilling and Sampling Devices
Hand-operated drilling and sampling devices 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 samplers are still suitable for use in
detecting the presence of pollutants. It is difficult to use these drilling
and sampling devices in contaminated ground without transporting shallow
contaminants downward.
19
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Figure 3-7. Continuous sample tube system (Courtesy Central
Mine Equipment Co.)
20
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3,1.2.1 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 3-8). As many extension rods are used as
are required to reach the total drilling and sampling 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 exten-
sions are circumscribed by etched marks in even increments (e.g., in 6 inch
increments) above the base of the auger.
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.
3.1.2.2 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
3-9). 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 increments 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.
3.1.2.3 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 3-10, 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.
21
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Figure 3-8. Screw-type auger/spiral auger
22
-------
Cross handles and extensions are
available In two materials and lit all
extendable equipment.
'Vthinwall
lightweight
conduit
Forged regt>
' carbon aHoy
steel bits
: with stein's) nwd
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edges, shar
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Figure 3-9. Regular auger (Art's Machine Shop, 1982)
23
-------
HANDLE
SHANK
BARREL
BIT
Figure 3-10. Post-hole type of barrel auger
24
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3.1.2.4 Dutch-Type Auger--
The so-called Dutch-type auger is really a smaller variation of the
post-hole auger design. As shown in Figure 3-11, 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.
3.1.2.5 Regular or General Purpose Barrel Auger--
A version of the barrel auger commonly used by soil scientists and county
agents is depicted in Figure 3-9. 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 3i inches, but sizes ranging from H inches to
5 inches are available (Art's Machine Shop, personal 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 form lightweight conduit or seamless steel tubing. The extensions are
circumscribed by evenly-spaced marks to facilitate determining sampling depth.
3.1.2.6 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
3-12).
3.1.2.7 Mud Augers--
Another variation on the standard barrel auger design is available for
sampling heavy, wet soils or clay soils. As shown in Figure 3-13, 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).
3.1.2.8 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.
3.1.2.8.1 Soil sampling tubesAs depicted in Figure 3-14, soil sampling tubes
consist of a hardened cutting tip, a cut-away barrel and an uppermost threaded
segment. The sampling tube is attached to sections of extension rods (tubing)
to attain the requisite sampling depth. A cross-handle is attached to the
uppermost segment.
25
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Figure 3-11. Dutch auger (Art's Machine Shop, 1982)
26
-------
Figure 3-12. Sand auger (Art's Machine Shop, 1982)
27
-------
Figure 3-13. Mud auger (Art's Machine Shop, 1982)
28
-------
Figure 3-14.
Soil sampling tube (Clements Associates,
Inc., 1983)
29
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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 inches
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 lightweight, durable metal. Exten-
sions are available in a variety of lengths depending on the manufacturer.
Markings on the extensions facilitate determining sample depths.
Sampling with these units requires forcing the sampling tube in vertical
increments 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.
3.1.2.8.2 Veihmeyer tubeIn 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 3-15. As shown, these
units consist, of a bevelled tip which is threated 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.
3.1.3 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. It is important that, if the augers "hang up" and the operator looses
control of the machine, the operator should not attempt to stop rotation of the
machine by grabbing the handles.
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 to obtain an
encased core sample, an uncased core sample, a depth specific representative
sample or just a sample according to the requirements of the chemical analyses,
(2) suitability for sampling various soil types, (3) suitability for sampling
soils under various moisture conditions, (4) accessibility to the sampling site
and general site trafficability, (5) sample size requirements, and (6) person-
nel requirements and availability. The sampling techniques described in the
previous sections were evaluated for these criteria and the results are summar-
ized in Table 3-1. This section briefly reviews the selection criteria. The
important capability of being able to obtain a sample at depth that is not
contaminated from shallow sources is greatly enhanced by using the hollow-stem
auger drilling method.
30
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V
drive hammer
head
tube
point
Figure 3-15. Veihmeyer tube
31
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3.2.1 Capability for Obtaining Various Sample Types
An encased core sample can be obtained by using the continuous sample tube
system, Shelby tube or piston samplers, and split-barrel drive samplers of the
type that can be fitted with sealable liners. The continuous sample tube
system must be used with the hollow auger drilling method. Shelby tube, piston
and split-barrel drive samplers are best used with hollow auger drilling
systems to minimize contamination of otherwise uncontaminated samples.
An uncased core sample can be obtained with the same sampling equipment
and procedures that provide an encased core sample. The continuous sample tube
system and split-barrel drive samplers can be used without liners to provide an
uncased core sample.
A representative sample can be obtained with almost any sampling device,
if contaminated, or even uncontaminated, soil has not fallen to the bottom of
the borehole or has not been transported downwardly by the drilling process.
Use of the hollow auger drilling method provides the greater assurance that
contamination has not occurred from the drilling or sampling processes. When
representative samples are desired and continuous flight (solid-stem) auger
drilling or one of the hand-operated drilling methods is used, the borehole
must be made large enough to insert the sampler and extend it to the bottom of
the borehole without touching the sides of the borehole. It is suggested that,
if a hand-operated auger sampling method is used, a larger auger be used to
advance and clean the borehole than the auger-sampler that is used to obtain
the retained sample.
3.2.2 Sampling Various Soil Types
A split-barrel drive sampler can be used in all types of soils if the
larger grain sizes can enter the opening of the drive shoe.
Shelby tubes and the continuous sample tube system are best used in fine
grained (silts and clays) and in fine granular soils. Shelby tubes can be
pushed with the hydraulic system of most drill rigs in fine granular soils that
are loose to medium dense or in fine grained soils that are soft to medium
stiff. If denser or stiffer soils are encountered, driving of the tube sampler
may be required. The continuous sample tube system can be used to sample soils
that are much denser or harder than can be sampled with Shelby tubes, pushed or
driven.
Hand-operated samplers can be used in almost any soil type if there is
enough time availableeventually the hole will be completed. Within the above
sections, there is guidance provided on which hand-operated drilling device
works best according to the soil types and moisture condition.
3.2.3 Site Accessibility and Trafficability
Site accessibility depends upon what the owner will permit. Trafficabil-
ity relates to the capability of various vehicles to reach a drilling location.
The availability of multipurpose drill rigs on 4 x 4 or 6 x 6 trucks or on
all-terrain carriers or when the use of helicopters negates the problems of
trafficability except in exceptionally steep or wooded terrain. The relative
advantages of using hand-operated drilling and sampling devices involve a
32
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TABLE 3-1. CRITERIA FOR SELECTING SOIL SAMPLING EQUIPMENT
oo
Most Suitable Access, to Sampl.
Obtains Core Most Suitable Operation in Soil Moisture Sites During Poor Relative
Sample Core Types Stoney Soils Conditions Soil Conditions Sample Size
Type of Sampler Yes Mo Cob Coh'less Fav Unfav Wet Dry Inter Ves No SB Lg
Labor
Sngl
Req'mts
2/More
A. Power Drilling
1. Multipurpose Drill R1g X XX X X X X X XX
2. Drive Sampler XX X x XX
3. Thin-Nailed Tube Sampler XX XXX X
4. Peat Sampler 'XX XXX x
5. Continuous Sample Tube System X X X XXXX XX
6. Hand-Held Screw Type Potter Auger X X XX X
B. Hand Auger
1. Screw-Type Auger X XXXX
2. Barrel Auger
1. Post-Hole Auger XX XX X X
X
X
X
X
X
X
X
b. Dutch Auger XX X X
c. Regular Barrel Auger XX X XX X
d. Sand Auger XXX XX X
e. Mud Auger XX XX X X
3. Tube-Type Sampler
a. Soil Probe
(!) Met Tip X XXX
(2) Dry Tip X XXXX
b. Velhwyer Tube X X X
X
X
X
X
X
X
-------
comparison of the difference in costs of decontaminating a drill rig and tools
with the difference in quality of samples that can be obtained with two general
methods.
3.2.4 Relative Sample Size
When multipurpose drill rigs are used, the sample size will depend only on
the size of drilling tools used. Hollow-stem augers with 6.25-in. ID allow the
use of 5-in. OD Shelby tubes, 6-in. OD continuous sample tubes and 4.5-in. OD
split barrel drive samplers. If hand-operated tools are used, the use of
larger diameter models will facilitate obtaining large samples.
3.2.5 Personnel Requirements
Generally, it is good practice to have at least two people in the field on
all types of drilling and sampling operations. When multipurpose auger-core-
rotary drills are used, the speed of drilling and sampling which is much
greater than the speed of drilling and sampling and hand-operated equipment may
require a larger crew to efficiently handle, log, identify and preserve the
samples.
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 separately, randomly, and indepen-
dently 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 regional-
ized variable theory, has been employed to demonstrate a number of spatial
relationships for both soil chemical and physical properties. For many proper-
ties, a geostatistic analysis will indicate an approximate distance 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 inde-
pendence between sampling locations. The 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 3-16). 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.
34
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R-65W- j R-64W-
LAND TREATMENT BORDER
USEABLESITE
x DISCARD SITE
SCALE 1: 20,000
SOIL SERIES aaf bb, cc, dd
Figure 3-16. Random Site () selection example for unit cc
35
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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 3-16) 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 soil scientist may 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). Specify whether the x or y coordinate is chosen
first. Do not reinitiate the use of the table but continue
from where the last random number was selected. 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 (o) 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.
(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).
36
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Locations for monitoring on background areas should be randomly determined
using the following procedure:
(1) The background area must have characteristics (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 back-
ground study may be sufficiently large to preclude an inference that a statis-
tical difference exists with any confidence. A more appropriate and statisti-
cally 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 established
using the following procedures.
(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 3-17).
(2) Obtain one sample from each soil-core portion taken below the
treatment zone.
37
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TABLE 3-2. SUMMARY OF SOIL-CORE SAMPLING PROTOCOL FOR BACKGROUND AND ACTIVE LAND TREAMENT AREAS
Sampling
Area
Number of
Randomly
Selected
Core Samples
Sampling
Depth
Sampling
Frequency
co
oo
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)
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
Semiannually
-------
BACKGROUND
8 SOIL CORES FOR EACH SOIL SERIES
\ V7 INITIAL SOIL SURFACE
ACTIVE
6 SOIL CORES PER UNIFORM AREA
GJ
Id
M
15 cm (6 in)
t
TREATMENT ZONE
1
15 cm (6 in)
t
I
1.5
(5
i
i
ATL
1
(3
m
ft)
UNSATURATED
ZO
r
EAST
n
ft)
NE
SEASONAL HIGH WATER TABLE
Figure 3-17. Soil core sampling depths
-------
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 3-17).
(2) The pH sample from the treatment zone in each uniform area
should be obtained using the following procedure:
a. Select one representative sample from each soil-core
portion taken within the treatment zone.
(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 3-17).
3.4.1 Compositing Samples
While the RCRA Guidance Document: Land Treatment Units (EPA, 1983b) does
not recommend compositing of samples, under very uniform conditions compositing
may be considered. 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 compos-
ite 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. Materials 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--
A large plastic or canvas sheet is often used for compositing 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.
40
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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 at-
tempting to mix the soil.
After the soil is mixed, it is again spread out on the cloth to a rela-
tively 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 by simply depositing them back on the
treatment zone.
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 completeness
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 laboratory.
The excess soil is disposed of as waste.
An alternative method of compositing is to collect measured quantities of
subsamples from individual core segments. This eliminates the possibility of
disproportionately sampling individual cores, and gives each core roughly
equivalent weight in the composite sample. A plastic or stainless steel
measuring cup is recommended to collect equal volumes from each core.
3.5 SAMPLING PROCEDURE
It is assumed that the number and location of sampling locations within
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 (See Table 3-3 for a typical checklist) be prepared itemizing all of
the equipment necessary, both for sampling and for maintaining quality assur-
ance. Thus all of the tools needed for sampling should be itemized and located
41
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W!V;^"
v&'
es
\*v
-------
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
preliminary preparation will ensure that all equipment is on hand and that time
will not be wasted in returning to the operations 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 conditions.
Specifically, a severe problem with some 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. Under some geologic circum-
stances with some hand-operated drilling methods, perfect site preparation will
not eliminate downward transport of contaminants.
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 functioning 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.
3.5.2 Sample Collection with Multipurpose Drill Rigs
There are three principal advantages in using multipurpose auger-core-
rotary drill rigs for unsaturated zone sampling: (1) the work can be performed
rapidly in the most adverse environments such as extremely hot or extremely
cold and wet weather, (2) borings can be readily made in the densest or hardest
soil conditions, and (3) there is the greater capability of preventing downward
movement of contaminants during drilling and sampling. Also, with some samp-
lers the sample is encased as it is taken in a protective enclosure with
minimal atmospheric contamination or loss of volatile constituents. The only
disadvantage is the cost of decontamination of the drill and the tools.
It is suggested the Drilling Safety Guide (no date) published by the
National Drilling Federation (NDF) be read and studied in depth by all drilling
and sampling personnel before using auger-core-rotary drills.
3.5.2.1 Hollow-Stem Auger Drilling and Sampling--
The general process of using hollow-stem augers to simultaneously advance
and case a borehole was previously presented (Refer to Figures 3-1 and 3-2).
The following is a detailed yet generalized procedure:
(1) The outer and inner hollow-auger components (Figure 3-2A) are
assembled and connected by the shank on top of the drive cap
to the rotary drive of the drill rig.
(2) This assembly is advanced to the desired sampling depth using
the rotary action and ram forces of the drill rig. The auger
head cuts into the soil at the bottom of the hole and directs
the cuttings to the spiral flights which convey the cuttings
to the surface (Figure 3-2A).
43
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(3) The drive cap is disconnected from the auger column assembly.
The pilot assembly with the center rod column is then removed,
usually with a hoist line (Figure 3-2B).
(4) A sampling device attached to a sampling rod column is insert-
ed and lowered within the hollow axis of the auger column to
rest on the soil at the bottom of the hole. The sampling
device is then pushed with the hydraulic feed system of the
drill or driven with a hammer assembly into the relatively
undisturbed soil below the auger head (Figure 3-2C).
(5) The sampler is then retracted from the hollow axis of the
auger column. The sampler is either retracted with a hoist
line or by connecting the sampling rod column to the hydraulic
feed (retract) system of the drill rig. "Back-driving" may be
required to remove some samplers that are driven to obtain a
sample. In some soils, back-driving will cause some or even
all of the sample to be released from the sampler and remain
in the bottom of the borehole. Back-driving should not be
used when a hoist or the hydraulic feed of the drill can be
used to retract the sampler.
(6) The pilot assembly and center rod column is reinserted, the
drive cap is reconnected to the auger column and the rotary
drive of the drill rig. The hollow auger column is then
advanced to the next sampling depth.
(7) If sampling is required at depths greater than about 4.5 ft
plus the length of the sampler below the auger head, addition-
al 5 ft hollow auger sections and center rod sections are
added. The flights are timed and mated at the coupling to
provide a continuous conveyance of cuttings.
(8) Fill in the cavity with soil, tamping to increase the bulk
density of the added soil. Fill the hole to ground surface.
For some types of samplers, it is difficult to retain the sample in the
sampler because of the "vacuum" within (or apparent tensile strength of) the
soil at the bottom of the sample. After the sampler is pushed or driven, the
hollow augers can be advanced downward to the bottom of the sampler to "break"
the vacuum.
3.5.2.2 Continuous Flight Auger Drilling and Sampling
Continuous flight augers have hexagonal shank and socket connections which
prevert sampling through the usually small diameter axial tubing; consequently,
the complete auger column must be retracted and reinserted for each sampling
increment.
(1) The continuous flight auger assembly, i.e, auger head and 5 ft
flight auger section is connected by the top shank of the
auger to the rotary drive of the drill.
44
-------
(2) The auger assembly is advanced to the desired sampling depth
using the rotary action and ram forces of the drill rig
(Figure 3-3A).
(3) After rotation is stopped and the rotary power train of the
drill is placed in neutral, all cuttings are carefully removed
from the zone adjacent to the borehole. This will minimize
the amount of material that will fall to the bottom of the
borehole when the augers are removed.
(4) The auger column is then removed from the borehole without
further rotation (Figure 3-3B). The augers should be imme-
diately removed from the area of drilling to prevent cuttings
from the auger flights falling into the borehole, and it may
be necessary to remove cuttings from the area adjacent to the
borehole as the auger column is retracted.
(5) The sampling device on a sampling rod column is inserted and
lowered into the open borehole to rest on the soil at the
bottom. Care should be taken to minimize the contact of the
sampler and sampling rod column with the side of the open
borehole. The sampler is then pushed with the hydraulic feed
system of the drill or driven with a hammer assembly through
whatever cuttings that may have accumulated at the bottom of
the borehole into the undisturbed soil (Figure 3-3C).
(6) The sampler is then retracted from the borehole using the same
procedures and care described above for hollow auger drilling.
(7) If additional samples are required, the auger column assembly
is reinserted and the drilling and sampling sequence is
continued (Figure 3-3D).
(8) If sampling is required at depths greater than about 4.5 ft
plus the length of the sampler, additional 5 ft auger sections
are added.
(9) Usually the top of the sample should be "discarded" to assure
that cuttings that fall into the borehole do not provide false
data or contaminate the remainder of the sample.
(10) Fill in the cavity with soil, tamping to increase the bulk
density of the added soil. Fill the hole to ground surface.
3.5.2.3 Samplers
Various types of samplers and complete sampling systems are available for
use with hollow auger, continuous flight auger and other appropriate drilling
methods. The sampler used will depend upon economic availability, the type of
drill rig being used, the general nature of the project and specific sampling
requirements. The following are some of the common samplers and related
procedures commonly used in North America.
45
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3.5.2.3.1 Thin-walled volumetric tube samplers--Thin-wa11ed volumetric tube
samplers are commonly called Shelby tubes (from the original manufacturer's
nomenclature). Shelby tube samplers are described in 3.2.2.5.1. Shelby tube
samplers can be used in most soft to stiff fine grained soils and in some
granular soils. The Shelby tube is a rather ideal sampler in that the soil can
remain in the sample tube for transportation to a testing facility. Also,
Shelby tubes can be predrilled with smaller circular "sampling ports" that are
"taped over" during sampling and transportation to a test facility. At the
testing facility the sealing tape can be removed as required to obtain a small
cylindrical "plug sample" from the side of the larger sample. The procedure
for general use of Shelby tubes follows:
(1) The borehole is advanced to the sampling depth by the selected
method. When hollow-stem augers are used, the auger I.D.
should be at least 0.20 in. greater than the Shelby tube O.D.
When an open hole drilling method is used, the diameter of the
drilled hole should be at least 1.00 in. greater than the
Shelby tube O.D.
(2) The Shelby tube sampler is attached to the sampler head which
in turn is connected to a sampling rod column.
(3) The Shelby tube sampler assembly is lowered within the hollow
auger axis or open borehole to rest on the bottom.
(4) The sampling rod column is extended upward to contact the
retracted base of the drill rig rotary box.
(5) The sampler is then pushed into the soil at the bottom of the
borehole by using the hydraulic feed of the drill. The Shelby
tube should be pushed at a rate of about 3 to 6 inches per
second. Care should be taken to assure that the top of the
sampling rod column is squarely against a flat surface of the
rotary box and that there are no loose tool joints in the
sampling rod column. All members of the drilling and sampling
crew should stand away from the sampling rod as the sampler is
being pushed.
(6) The sampler should be allowed to "rest" within the soil for at
least one minute to allow the soil to expand laterally against
the inside of the Shelby tube. This surface contact will
improve sample recovery.
(7) The sampler is then pulled upward with a hoist line and
hoisting swivel or by connecting to and using the hydraulic
feed system of the drill rig. In some cases sample recovery
may be improved by rotating the sampler after it has been
pushed and allowed to expand against the inside of the Shelby
tube.
(8) The Shelby tube with sample enclosed is detached from the
sampler head.
(9) Any loose material on the "top" of the sample should be
removed with a large spoon, a putty knife or a similar tool.
46
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(10) If the sample is to be shipped to a testing facility within
the tube, the tube ends should be sealed immediately. Sealing
is best accomplished by using expanding soil seals (Figure
3-6A, 3-6B) and then capping the ends of the tubes with
"plastic" caps and sealing tape.
(11) It may be appropriate to extrude the samples in the field, in
which case a hydraulic extruder (Figure 3-18) is used.
Following extrusions, the samples are then placed in large,
wide-mouthed jars or other scalable containers.
(12) Fill in the cavity with soil, tamping to increase the bulk
density of the added soil. Fill the hole to ground surface.
3.5.2.3.2 Piston samplersPiston samplers usually consist of a Shelby tube
sampler with a samplinghead that contains a piston follower. The piston
follower rests on the soil surface within the Shelby tube prior to and during
pushing of the tube into the soil. The piston is then "locked" in position to
provide a vacuum on top of the sample to react against the vacuum at the bottom
of the sample which develops as the tube and soil sample is pulled out of the
soil. Sampling procedures for piston samplers are identical to those for
common Shelby tube samplers except for the activities involving the locking of
the piston and the breaking of the piston vacuum to remove the sample tube and
sample from the sampler head. There are different types of piston sampler
heads according to the piston locking mechanism. Generally, it is only advan-
tageous to use a piston sampler over a common Shelby tube sampler in soft, wet
soils. Piston samplers will often provide optimum sample recovery in soft, wet
organic soils.
3.5.2.3.3 Split barrel drive samplersThe split barrel drive sampler assembly
consists of a drive shoe, two split barrel halves and a sampler head as des-
cribed in 3.2.2.5.2. Split barrel samplers are used with the same procedures
as thin-walled volumetric samplers as described above in 3.5.2.2.1 except that
in almost all cases the sampler is driven into the soil using a hammer assem-
bly. The common 2-in. O.D. Sampler is typically driven with 140 Ib drive
weight. Larger samplers are often driven with 300 Ib, 340 Ib or 350 Ib drive
weights. Granular samples are often retained with the aid of various spring
and flap-valve retainers (Figure 3-19).
3.5.2.3.4 Continuous sample tube systems--The "continuous sample tube system"
is a patented sampling system which consists of a 5 ft long sample barrel as
described in 3.1.1.5.3 (Figure 3-7). The continuous sample tube system works
best in fine grained soils but has been used in granular soils with success.
The sample barrel is used in conjunction with hollow-stem augers as follows:
(1) The sample barrel assembly is inserted within the first hollow
auger to be advanced and connected to a hexagonal extension
that passes through the drill spindle with bearing assembly to
a stabilizer plate above the rotary box.
(2) The hollow auger is coupled to a flightless auger section that
is connected to the drill spindle. The cutting shoe of the
auger barrel will extend a short distance in front of the
auger head when the assembly is completed.
47
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-SAMPLE
HYDRAULIC CYLINDER
09 cm
.£=>
CO
Figure 3-18. Core sample extruding device
-------
(a)
(b)
Figure 3-19.
Soil core retainers for sampling in very wet soils
and cohensionless soils, (a) One-way solid flap
valve, (b) Spring-type, segmented basket retainer
49
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(3) The cutting shoe advances Into the soil as the augers are
rotated and advanced into the soil.
'4) The hollow augers and sampler assembly is usually advanced
until the drill spindle "bottoms out."
(5) The auger is then disconnected at the top from the flightless
auger section.
(6) The sample barrel is then hoisted upward, leaving the hollow
auger in place.
(7) The sample is then removed from the sample barrel. Treatment
of the sample will be generally like the treatment of Shelby
tube samples but will depend specifically on whether or not a
"split" or "solid" outer barrel is used or whether or not
liners are used. Typically clear "plastic" liners are used
within a split outer barrel for efficient processing of
samples. These liners with soil can be processed for transporta-
tion using the same procedures that are used for Shelby tube
samples.
(8) When greater sampling depths are required additional 5 ft
auger sections and hexagonal drill stem extensions are used.
Obtaining optimum recovery with the continuous sample tube
system requires some trial-and-error adjustments by the
driller. Generally, recovery approaching 100 percent is
readily obtainable in fine grained soils. In some angular
granular soils it is advisable to only advance the system in
2.5 ft increments to obtain optimum recovery.
(9) Fill in the cavity with soil, tamping to increase the bulk
density of the added soil. Fill the hole to ground surface.
3.5.2.3.5 Peat samplerThe peat sampler is seldom used. However, under some
circumstances it may provide the optimum sampling method.
(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 step, 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.
(5) Extrude the sample into a clean sample container. Label the
container.
50
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(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 Hand-Operated Equipment
In the following section, step-by-step sample collection procedures are
described for each of the major soil-sampling devices.
3.5.3.1 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.
3.5.3.2 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.
51
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(1) Locate auger bit on soil surface at exact sampling location.
(2) With the auger and extension rod in an exactly vertical
position, turn and pull down on the handle (see Figure 3-20).
(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.
3.5.3.3 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.
52
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3-20.
'
53
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(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 3-21.
3.5.3.4 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.
54
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en
en
HOW DOES THE BACKSAVER 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 cor* 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.
17) Remove the full sampling tube by lining 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.
18) Empty the sampling tube and clean.
(9) Steps 3 through 8 arc repeated until the desired depth Is reached.
Procedure used to pull a soil core with a sampling tube equipped with the
"Backsaver N-2 Handle."
Same as steps 1 and 2 above.
. j
Figure 3-21. Operation of "backsaver" handle with soil sampling tube
(Clements Associates, Inc., 1983)
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(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 contamination 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.
56
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3.5.4 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 contaminants. A set
of tools should be available for each sampling site where cross contamination
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
i terns.
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 wrenches
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 decontam-
ination procedures. With the exception of highly volatile solvents, washing
solutions can be safely disposed at the land treatment facility being sampled.
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.
57
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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.
t 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.
0 Rinse twice in spectrographic grade methylene chloride or
hexane, saving the solvent for use in step 3.
Air dry the equipment.
0 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 collection
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 obtain-
ing soil cores at sites used to dispose of particularly toxic or combustible
wastes.
The problem of operator contact with hazardous wastes and the possibility
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 follow-
ing 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.
58
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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 protec-
tive 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 protec-
tion. 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-ct)%) confi-
dence interval (Eq. 3-3) are first calculated by the following equations:
n
y = £ y./n (3-1)
1=1 1
59
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TABLE 3-4. PERSONNEL PROTECTIVE EQUIPMENT
(Zirshky and Harris, 1982)
Level 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
60
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v(y) = "(y, - y)2/n(n-i) (3-2)
1=1 n
where y, = ith sample
n = number of samples
y = sample mean
V (y) = estimated variance of the mean
L = y ± tQ/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
(tc) with the critical value ta, where ta is the upper tail value from the
t-distribution with n, + n^ - 2 degrees of freedom at the a significance
level. If t > ta, there is a statistically significant increase in the
uniform area (active portion) mean over the background area mean.
c 2p
t = ( - y2) s (l/nx + 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
61
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2
s = pooled variance calculated
" by formula Eq. 3-5
n. = number of samples in area k
2 n, 2 n2 2
s n = 2 (y. - y,) + z (y, - y«) (3-5)
n, + r\p - 2
62
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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 re-
ceived 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 cup 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
pore-liquids.
Although a number of techniques are available for indirectly monitoring
the movement of pollutants beneath waste disposal facilities, soil core samp-
ling and suction-cup lysimeters, remain the principal methods for directly
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 constituents.
Lysimeters have been used for many years by agriculturists for monitoring the
flux of solutes beneath irrigated fields (Biggar and Nielsen, 1976). Similar-
ly, they have been used to detect the deep movement of pollutants beneath land
treatment units (Parizek and Lane, 1970). Inasmuch as lysimeters are the
primary tools for soil pore-liquid monitoring at land treatment units, under-
standing 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.
63
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45
4OH
35
u
i 30-
m 20-
H
5 is
^ 10
a.
5-
0
POROSITY
SPECIFIC RETENTION
UJ
UJ
I CO
cr
o
o
Figure 4-1. Variation of porosity, specific yield, and
specific retention with grain size (Scott
and Scalmanini, 1978)
64
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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 demonstrated 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 demon-
stration. 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 particles,
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 contents,
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 ?
*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.
65
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0.8 1
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)
66
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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 samplers, (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. Basically,
ceramic-type samplers comprise the same type of ceramic cups used in tensio-
meters. 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 inter-
action 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.
67
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PLASTIC TUBE
WATER
SAMPLE^
VACUUM TEST HAND PUMP
VACUUM
COLLECTED SOIL-WATER SAMPLE
Figure 4-3. Soil-water sampler (Courtesy Soilmoisture
Equipment Corp., 1978)
68
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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. At land treatment
units, however, polyethylene or teflon tubing is recommended.
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 pressure is applied.
The dead space below the porous section, however, will result in potential
cross contamination.
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 subsection.
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 pressures 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.
69
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,2-WAY PUMP
PLASTIC TUBE
AND CLAMP
VACUUM PORT
AND GAUGE
PLASTIC TUBE
AND CLAMP
PRESSURE
VACUUM IN
BENTCNITE
2/16HNCH
COPPER TUBE
PLASTIC PIPE
24 INCHES LONG
6-INCH HOLE
WITH TAMPED
61UCA SAND
' 8ACXF1LL
POROUS CUP
BENTONITE
SAMPLE BOTTLE
DISCHARGE TUBE
Figure 4-4. Vaccum-pressure sampler (Parizek and
Lane, 1970)
70
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PRESSURE/VACUUM INLET-
2nneft 0.0. PVC TUBE-
COLLECTION CHAM8EH-
THREAOEO COUPLING
-EXTRACTION OUTLET
-THREADED COUPLING
-RIGID 1/4-.ncn l.D. PVCTU8E
POROUS METERIAL
PVC WELL POINT
Figure 4-5. Modified pressure-vacuum lysimeter
(Morrison and Tsai, 1981)
71
-------
Li
-VACUUM-AIR PRESSURE LINE
UPPER CHECK VALVE
VMPLE DISCHARGE LINE
.UPPER CHAMBER
-LOWER CHECK VALVE
-TUBING
LOWER CHAMBER
t SUCTION CUP
Figure 4-6. "Hi/pressure-vacuum soil-water sampler" (Courtesy
Soilmoisture Equipment Corp., 1978)
72
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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 surrounding soil. The amount of vacuum is determined
from tensiometers. Hoffman et al. (1978) used this type of sampler to collect
samples of irrigation 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 solution
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 extrac-
tion devices for obtaining soil solution samples for determining EC, Ca, Mg,
and P04-P. Their suitability for NOo-N is questionable." They also conclude
that hollow fiber samplers are more sdited to laboratory studies, where ceramic
samplers are more useful for field sampling. Because of the high potential to
alter sample quality, further research is required on these types of samplers
before they can be recommended.
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.
73
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CROSS SECTION
AA
ADJUSTABLE
VACUUM
SOIL
SOLUTION
DUAL CHAMB
TRICKLE TUBING
SAMPLING
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)
74
-------
SOIL
SAMPLING TUBE
FILTER SUPPORT/BASE
"SWINNEX"
FILTER HOLDER
MEMBRANE FILTER
LASS FIBER PREF1LTER
LASS FIBER "WICK"
! 1* «*
ww
««.
«*.-«. i »
. _ «»;.-
yyfo:':-::';-;:':.v
FIBER
COLLECTOR
//
// / / /
SOIL
Figure 4-8. Membrane filter sampler (Stevenson, 1978)
75
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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 presence of macropore or fracture flow should be determined 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 significant potential to contaminate
groundwater. The pan lysimeter, which is a free drainage type lysimeter is
suited for sampling macropore or fracture 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 collec-
ting 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 pro-
motes 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 is expensive, requires intensive instal-
lation procedures and a continuous vacuum. The "Swinnex" sampler has difficult
installation procedures and produces too small a sample. Some samplers, such
as the aluminum oxide porous cup sampler, 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 simple vacuum lysimeter cannot be used in situ
with the sampler totally covered by soil.
76
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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
77
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00
Figure 4-10. Free drainage glass block sampler
-------
In most cases, the lysimeter of choice at land treatment units will be
pressure-vacuum ceramic lysimeters. Teflon models have certain limitations
which preclude their use at soil suction conditions recommended for land
treatment units (Everett et. al., 1986). 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.
Free drainage 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 constituents that can
be lost from the soil by leaching. Free drainage samplers have the following
characteristics:
1) It is a continuously sampling "collection" system without the
need for externally applied vacuum.
2) Because vacuum is only used to pull the sample to the surface,
there is less potential for losing volatile compounds in the
sample obtained.
3) Its defined surface area may allow quantitative estimates of
leachate.
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.
6) Since the inside of the glass block type is uneven, the
potential exists for cross contamination from residual
samples.
7) If the glass blocks are not installed perfectly level, a sump
or collection area can result in dead space where the sample
cannot be removed.
8) Pan lysimeters require trenching to be installed. At land
treatment sites where the treatment zone includes 1.5 m (5 ft)
plus some build up of the land surface, the trenches may
require "shoring up."
79
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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
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 conducting
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 HC1 seep through them, and rinse thoroughly by
allowing 15 to 20 liters of distilled water to seep through. This cleaning
process can be accelerated by placing the distilled water inside the lysimeter
and developing 20-30 psi of pressure to drive the water through the porous
material. 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.
Prior to taking the suction lysimeters in the field, each lysimeter should
be checked for its bubbling pressure and for leaks. Complete procedures for
testing for leaks and air entry values are given in Everett et. al (1986).
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
3-16). A qualified soil scientist should be consulted in
completing this step.
80
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TABLE 4-1. SUMMARY OF GUIDANCE ON PORE-LIQUID SAMPLING
Location
Number of Units
Location of Sampling
Portion of Unit Frequency
Background
2 each on similar
soils found on
treatment area
With 12 inch depth
below treatment zone
Active
a. Uniform area
less than 12 acres:
6 units
b. Uniform area
greater than 12
acres: 2 per 4 acres
With 12 inch depth
below treatment zone
Quarterly.
If samples
cannot be
obtained
quarterly,
they should
be timed to
follow a
rainfall
event.
Quarterly.
Samples
should be
obtained 24
hours after
waste
application
events.
81
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(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.
(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 determined
using the following procedure:
(1) 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.
82
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(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-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 coordin-
ates 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 3-16) 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 after a rainfall has
occurred.
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
83
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00
NEC-1
SAMPLING
STATION
EM 1
SAMPLING
STATION
DIKE
'' ''
Z Z'//
-------
BACKGROUND
2 SOIL PORE LIQUID
MONITORING DEVICES
FOR EACH SOIL SERIES
ACTIVE
6 SOIL PORE-LIQUID
MONITORING DEVICES
PER UNIFORM AREA
INITIAL SOIL SURFACE
oo
en
30cm
(12 in)
TREATMENT ZONE
30 cm
:r
1.5m
(5ft)
UNSATURATED
ZONE
AT LEAST
1 m
Oft)
SEASONAL HIGH WATER TABLE
Figure 4-12. Pore liquid sampling depths
-------
LAND SURFACE
TRENCH WALL
TREATMENT ZONE
V-BENTONITE
200-MESH SILICA SAND
Figure 4-13. Location of suction lysimeters
86
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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
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.
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 installation 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 con-
struct 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 trench, which may be up to 10 m (30 ft) in length will
require the use of trenching equipment. For short distances, the trench can be
1.5 m (5 ft) deep as shown in Figure 4-14. For longer distances the trench can
be half as deep as presented, with the leads from the lysimeter running through
the shaft to a level closer to the land surface. Available trenching 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.
87
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SHELTER
00
00
>
Q
0
oc
1 fl
c
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.-;
-
..':- "' r. ':'." .]'-. V ."...,... . .:.-,, .".;:-'/'-
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..f;.v:--_-;.i'.;...; ;_;: =
'.' .' '
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s .' ^ '
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,'-.*! /, ' '. V
SHELTER
TOP VIEW
SHAFTi
6 ft x 6 ft x 5 ft
/
'/^'TR'EATMENT'ZONE//' |/'///
/'/ , ./ ////// ' f /\ i t
'/I, 'I'/'//'/ KAAN/IRJIIIAJ1
. //
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
-------
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
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 co'nduit, 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:
89
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STEEL HOUSING WITH
HINGED STEEL DOOR
MANIFOLD HOUSING
ACCESS LINES
FROM INDIVIDUAL
SAMPLERS
VACUUM (PRESSURE) BOTTLE
PRESSURE-VACUUM
RELIEF VALVE
10
o
^ PRESSURE-
VACUUM LINES
TO PORE-LIQUID
SAMPLERS
CONDUIT
FOR BURIED
ACCESS LINES
Figure 4-15. Above ground shelter for sample bottles and accessories
(side view)
-------
LAYER OF EARTH
HINGED, STEEL DOOR
SIDE VIEW OF SHELTER
PRESSURE-VACUUM
RELIEF VALVE
TANK VALVE
VACUUM (PRESSURE) TANK
MANIFOLD WITH LINES FROM
INDIVIDUAL SAMPLERS
TO
SAMPLERS
TO |
SAMPLERS
BURIED CONDUIT
FOR ACCESS LINES
- STEEL
HOUSING
SAMPLE BOTTLES
TOP VIEW
Figure 4-16. Burial shelter for sample bottle and accessories
91
-------
When installing the tubes, one tube should be pushed through the neoprene
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 "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 4-17), 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 available
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 4-13) 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 through a i" 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
92
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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 (Soil moisture Equiment Corp., no date)
93
-------
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
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 recov-
ery of the unit at some future time. Surveying in the units in background
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 excava-
ted 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
94
-------
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)
95
-------
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.
4.7 OPERATION OF VACUUM-PRESSURE SAMPLING UNITS
It is advisable to select a permanent 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.
96
-------
PRESSURE
PORT
ID
I
PINCH CLAMP
OPEN
(PRESS. VAC.
ACCESS TUBE)
PINCH CLAMP
CLOSED
(PRESS. VAC.
ACCESS TUBE)
VACUUM PORT
PINCH CLAMP
CLOSED
(DISCHARGE
ACCESS TUBE)
(A)
PULLING A VACUUM
PINCH CLAMP
CLOSED
(DISCHARGE
ACCESS TUBE)
PINCH CLAMP
OPEN
(PRESS. VAC.
ACCESS TUBE)
PRESSURE
PORT
PINCH CLAMP
OPEN
(DISCHARGE
ACCESS TUBE)
COLLECTED
WATER
SAMPLE
(C)
SOIL WATER SAMPLE
Figure 4-19.
(B)
Stages in the collection of a pore-liquid sample using a
vacuum-pressure sampler (Soilmoisture Equipment Corp.,
no date)
-------
(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.
(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.
4.7.1 Porous Segments in Lysimeters
The vadpse (unsaturated) zone consists of a mixture of soil particles,
water that is held on the surface of the particles and in small capillary
spaces between the particles, and interconnecting air passages that are open to
the atmosphere at the soil surface. Removing moisture for chemical analysis
from the vadose zone requires the use of special porous materials. Simply
exerting a suction on an open tube inserted into the vadose zone will not
remove moisture since the interconnecting air passages in the soil will result
only in the flow of air into the evacuated tube. However, by using a porous
cup sealed to the end of the tube, samples can be removed by suction, providing
the diameter of the individual pores in the porous cup do not exceed a critical
value.
If the porous cup is fabricated from a hydrophilic material, such as
ceramic, water will fill the pores of the cup completely. The water bonds to
the porous ceramic and cannot be removed from the pores unless the air pressure
differential across the wall of the cup reaches a critical value which is
related to the pore size. If the porous cup is fabricated from a hydrophobic
material such as PTFE (polytetrafluoroethylene), water will fill the pores of
the cup but the bonding of the water to the hydrophobic material will be less.
The air pressure required to force air through a porous cup which has been
thoroughly wetted with water is called the "bubbling pressure" or "air entry
value." The smaller the pores in the cup the higher this pressure will be.
The relation of the pore size to the bubbling pressure or air entry value is
defined by the equation D = 30Y/P, where D is the pore diameter measured in
microns. P is the bubbling pressure or air entry value measured in millimeters
of mercury and Y is the surface tension of water measured in dynes/cm.
In order to build a soil water sampling device which can be used success-
fully in the vadose zone to withdraw moisture from the soil, the device must
incorporate a porous cup which has pores so small that the air in the soil,
98
-------
under atmospheric pressure, cannot enter even though a full vacuum is created
within the sampler. Under these conditions, water from the capillary spaces in
the soil will flow through the pores in the porous cup and into the sampler but
air will not enter.
With respect to the above equation, the maximum size of the pores that
will permit this action are as follows: At 20°C the surface tension of water
is 72 dynes/cm. The maximum air pressure is 1 atmosphere or 14.7 psi or 760
millimeters of mercury. In accordance with the equation, the maximum pore size
in the porous cup would be D = (30)(72)/(760) = 2.8 microns. The pore size of
ceramic cups is between 2 and 3 microns. If the pores of the wetted sampler
cup do not exceed 2.8 microns in diameter, then a full vacuum can be maintained
within the sampler and the water films in the pores of the porous cup will not
break down. If the pore size of the cup is twice this amount, namely 5.7
microns, then the maximum vacuum that can be pulled within the sampler is 380
millimeters of mercury or 50 percent of an atmosphere. Likewise, if the pore
size is twice again as large, namely 11.4 microns in diameter, then the maximum
vacuum that can be pulled without the cup leaking air is 190 millimeters of
mercury or 25 percent of an atmosphere. Since the majority of the pores used
in PTFE suction lysimeters is between 70 and 300 microns, the bubbling pressure
is only 4 percent of an atmosphere.
Where porous materials are being used in air-water systems, such as in
suction lysimeters, the most direct method of evaluating the pore size of the
material is through the use of air pressure. By thoroughly wetting the porous
material and then exposing one side of it to increasingly higher air pressure
values, with the other side under water, one can readily observe when the air
pressure becomes high enough to enter the pores and cause bubbling on the
opposite side. The specific air pressure at which this bubbling occurs is a
direct measurement of the pore size as defined by the above formula and indi-
cates directly the effectiveness of the porous materials to withstand air
pressure differentials when in use. Evaluating pore size distribution by the
mercury intrusion method or other means does not give direct information as to
how the porous material will perform in the air-water system in which it is
used. PTFE pores are generally round and symmetrical, while ceramic pores are
of various ragged shapes. The strength of the water meniscuses in the indivi-
dual pores are a function of pore shape as well as overall size, and for this
reason an accurate measurement of the pressure at which the meniscus will break
down and allow air to enter can only be made accurately by direct measurement
of the bubbling pressure or air entry value of the wetted porous material.
As shown in Figure 4-20A, the pores within a suction lysimeter will not
hold a vacuum in a dry condition. Air can move freely from the soil or silica
flour surrounding the lysimeter through the pores into the interior part.
Thus, suction lysimeters should be installed in a wetted condition and silica
flour should be added as a slurry (one pound to 150 ml of water). One should
recognize that Figure 4-20 is highly diagrammatic and that each pore is repre-
sentative of a tortuous route through the cup wall. In reality, millions of
these tortuous pore routes are located throughout the cups. As shown in
Figure 4-20B, the pores become completely filled when the cup has been placed
in a wet environment and the pressure on both sides of the cup wall is one
atmosphere. As shown in Figure 4-20C, the surface tension of the wetted pore
begins to change as a suction is developed within the cup. As noted in
Figure 4-20D, the radius of curvature of the surface tension decreases as the
99
-------
OUTSIDE OF LYSIMETER CUP WALL
INSIDE OF LYSIMETER CUP WALL
A SOIL/SILICA FLOUR
ATMOSPHERIC
PRESSURE (1 bar)
ATMOSPHERIC
PRESSURE (1 bar)
ATMOSPHERIC
PRESSURE (1 bar)
c AIR ENTRY
(BUBBLING PRESSURE)
CERAMIC/PTFE CUP
| CERAMIC-2-3 microns
PTFE-70-90 microns
WETTED (PORES FULL)
ATMOSPHERIC PRESSURE (1 bar)
LYSIMETER SUCTION (2 cb)
LYSIMETER SUCTION 4 cb
LYSIMETER SUCTION
>233cb* CERAMIC
VACUUM >100 cb NOT POSSIBLE
Figure 4-20. Diagrammatic view of lysimeter cup wall
100
-------
suction within the cup increases. The ability of water molecules to withstand
these pressure gradients is the reason that air will not enter the cup even
though the-interior of the cup has been evacuated. Water, on the other hand,
will freely move through the wetted pores under the gradient induced by the
negative pressure within the cup. As developed under the previous para-
graphs, the surface tension is greatly increased by the reduction in pore
size. As demonstrated in Figure 4-20E, the surface tension in the pore can be
broken by increasing the gradient across the cup wall to greater than the
bubbling pressure of the cup. The bubbling pressure of low-flow ceramic cups
is between 35 and 45 psi, which translates to a suction of 233 centibars. The
bubbling pressure of PTFE cups is between 0.75 and 1 psi, which translates to a
very narrow operating range of 7 centibars (Everett et. al, 1986).
Once a sample has been obtained in the suction lysimeter, as evidenced by
a reduction in the suction gauge, pressure must be applied to the lysimeter
interior to push the sample to the surface. When a pressure is exerted on the
porous segment, the meniscus will extend away from the center of the suction
lysimeter. If too much pressure is applied within the suction lysimeter, the
sample may be expelled through the pores. The meniscus behavior, therefore, is
a function of the vacuum, pressure, pore size, porous material, soil moisture,
and soil texture.
4.7.2 Dead Space in Lysimeters
As a part of the experiments dealing with reduction in flow rate as a
function of increased soil suction, Everett et. al (1986) determined that
"dead" spaces may exist within suction lysimeters. As shown in Figure 4-21,
the ceramic cups are glued to the inner wall of a Schedule 20 PVC body tube.
This results in a projection, or lip, on the inside of the suction lysimeter.
As polyethelene tubes are pushed down or twisted through the two-holed stopper
at the top of the lysimeter, they develop a characteristic twist in their
length. (The tubing, in most cases, is delivered on a spool and tends to
retain a residual bend.) The polyethelene tube may catch on the inside lip of
the cup and the operator may conclude that the tube has reached the bottom of
the ceramic cup. Since the bottom of the cup cannot be seen, it is difficult
to determine whether the tube has actually reached the bottom of the cup. Even
measuring with a tape rule may result in the tape rule hanging up on the edge
of the cup, giving the impression that the depth to the bottom of the cup has
been determined. As a result, an 80-ml error can occur in any rate determina-
tions. This 80 ml of fluid accumulates in the cup and cannot be extracted
through the discharge line.
In all-PTFE suction lysimeters, the discharge line is a rigid PTFE tube
extending to the bottom of the PTFE cup. This design results in zero dead
space in the all PTFE lysimeters. However, the PTFE cups with a PVC body tube
have been designed with a rigid interior tube which does not extend to the
bottom of the PTFE cup. Since it is impossible to extend this rigidly fixed
interior tube, PTFE/PVC units have a constant dead space of 34 ml. The authors
are aware of numerous lysimeter investigations where rates of intake and
volumes of samples have been reported. To date, most operators, including the
manufacturers, have not been aware of the potential dead space within their
lysimeters (Everett et. al, 1986).
101
-------
I
I
I I
DISCHARGE TUBE j j
PVC (schedule 120)
CERAMIC CUP
TUBE CUT ON BEVEL
BOTTOM OF CUP
Figure 4-21. Location of potential dead space in suction lysimeters
102
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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 physical
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 analy-
sis. 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 prepar-
ates (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 (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., intrapedal 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 suctioncup
samplers collect water from these finer pore sequences, the resultant samples
will not be representative of the bulk flow.
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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 samplers
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 documented at each
profile. If such cracks appear to be widespread, alternative sites or monitor-
ing techniques (e.g., pan lysimeters) should be examined. However, it should
be borne in mind that even large cracks frequently diminish in width in deeper
reaches of the profile. If it is found that structural 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 monitoring approach (i.e., suction
or pan lysimetry) and to evaluate the acceptability 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, chemical interactions, or bacterial buildup. The problem of clogging
by particulate matter is not as severe as once thought (Everett et. al, 1986).
Apparently, soils have the capacity to filter out the fine material before
reaching the porous segments. Several studies have been reported involving the
use of suction-type samplers for monitoring pollutant movement at land treat-
ment 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 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 irri-
gated 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 possible, 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
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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, install-
ing 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 estima-
ted 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 essen-
tial that each cup be preconditioned in accordance with recommended practice,
i.e., flushing with 8N HC1, followed by rinsing with distilled water.
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 recommended 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.
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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 hand-
ling. 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 exer-
cised, 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
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 (Everett et. al, 1986).
However, the flow rates will be so low that effectively one cannot get a
sample. If the tensiometer readings are between 0 and 60 centibars of suction,
the suction lysimeter 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
106
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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 4-22). 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.
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 4-22, 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 4-23 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 (^ 1.5 m from the soil surface), but a
significant distance above the trench floor (see Figure 4-23). A discharge
107
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PLYWOOD ROOF WITH
GALVANIZED'
SHEET METAL COVER
PAN LYSIMETER.
PEA GRAVEL-
2 x 12-inch siding and 4 x 4-inch
timbers. All wood treated with
with preservative.
.GUTTER DRAIN PIPE
**"* L/ 1
1
\ PLASTIC
^-/TUBING
-R SAMPLE
.(J*' BOTTLE
-' x^'
PIPE *t
i
j
^,
-
&--
RESIDUAL SOIL
STRATIFIED SILT,
CLAY, AND SAND
SCREEN ON
FLOOR DRAIN
DOLOMITE BEDROCK
Figure 4-22. Trench lysimeters installed in trench shelter
Parizek and Lane, 1970)
108
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SAMPLING TUBE
INSTALLATION TRENCH
(BACKFILLED AFTER LYSIMETER INSTALLATION)
o
to
. m
TREATMENT
ZONE
WATER TABLE
V7
TRENCH LYSIMETER
OR GLASS BLOCK
Figure 4-23. Pan lysimeter installation
-------
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 (^ 1.5 m from the soil
surface), but a significant distance above the trench floor (see Figure 4-23).
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
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 4-23). 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.
110
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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 backfilled 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.
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.
Ill
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Pressure-Vacuum Lysimeters. J. of Hydrol. 11:1-21.
Parizek, R.R., 1984. Personal Communication. Penn. State U., University
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R-4
-------
Rhoades, J.D., and L. Bernstein, 1971. Chemical, Physical, and Biological
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R-7
-------
-------
APPENDIX A
Table of Random Units
(Standard Mathematical Tables, 1973)
A-l
-------
TabU of Random Units
RANDOM UNITS
UM of Table. If one wishes to select a random sample of N items from a universe of
Af items, the following procedure may be applied. (M > ,V.)
1. Decide upon some arbitrary scheme of selecting entries from the table. For exam-
ple, 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 items in the universe from 1 to M. Thus, if M =
500, the items 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 £Af, the correspondingly designated item in the uni-
verse is chosen for the random sample of ..V 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-2
-------
Table of Random Units
Line/Col.
:
2
3
4
5
8
1
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
(1)
10480
22368
24130
42167
37570
77921
99662
96301
89579
85475
28918
63553
09429
10365
07119
51085
(2)
15011
46573
48360
93093
39975
(3)
01536
25595
22527
06243
81837
069071 11008
72905
91977
14342
36857
69578
40961
93969
61129
97336
12785
56420
05463
63661
43342
88231
48235
52636
(4)
02011
85393
97265
61680
16656
42751
69994
07972
10281
53988
33276
03427
92737
87529 1 85689
71048
51821
08178
51259
02368 j 21382 1 52404 1 60268
01011
52162
07056
48663
54164
54092
53916
97628
91245
58402
32639 j 32363
29334
25 02488
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
81525
29076
00742
05366
91921
00582
00725
69011
25976
09763
27001
33062
72296
20691
57392
04213
26418
04711
69884
65797
57948
83473
(5)
81647
30995
78393
07856
(6)
91646
89198
64809
16376
06121 { 91782
27756
98872
18876
17453
53060
70997
49626
88974
48237
77233
77452
89368
53498
31016
20922
18103
59533
79936
69445
33488
5*267
13916
16308
19885
33362 94904 31273104146
46369 158586 12321 6
33787 j 09998
85828
22421
05597
87637
28834
04839
68086
39064
25669
64117
87917
82797
95876
29888
73577
91567
17955
46503
92157
14677
98427
34914
70060
53976
76072
90725
64364
08962
95012
_ » i/uuu
42595
56349
18584
89634
62765
07523
63976
28277
54914
29515
52210
67412
00368
68379
10403
27958
42698
14513
06691
14346 | 09172
74103
24200
87308
07351
96423
38432
66432
26422
94305
77341
56170
55293
88604
12908
30134
90999 49127
18845 49618
94824 78171
35605 81263
I
33362
88720
39475
06990
40980
83974
33339
31662
93526
64270
82785
46473
67245
07391
29992
31926
25388
70765
20492 | 38391
47070
13363
58731
29731
24878
46901
84673
44407
28766
42206
86324
18988
67917
30883
04024
20044
02304
84610
39667
01638
34476
23219
68350
58745
65831
14883
61642
10593
91132
30168
25306
(7)
69179
27982
(8)
14194
53402
15179 ) 24830
39440 1 53537
60468 1 81305
18602
(9)
62590
93965
(10)
36207
34095
49340 1 32081
71341
49684
1
70659 90655
71194 | 18738
94595
57740
38867
56865
18663
36320
56869
84378
62300
05859
72895
17617
67689 { 93394
47564
60756
55322
81056
92144
44819
44013
69014
25331
08158
90106
57004
60672
15053
48840
60045
12566
17983
31595
52180 1 20847
30015
01511
97735
49442
01188
18594 1 29862 71585
(11)
(12)
20969 i 99570
(13)
91291
(14)
90700
52666 1 19174 1 39615 1 99505
30680
00849
19655 1 63348 1 58629
74917 1977581 16379
141 10 106927
21916
63213
18425
58678
16439
01547
12234
08272 |84115
26358
85977
53900
65255
85104
29372
70960
64835
85030(51132
83149 I 98736 23495 1 A4350 1 94738
76988
90229
76468
38005 94342
00256
92420
82651
20849
40027
44048
25940
35126
88072
27354
48708
18317
86385
59931
51038
82834
47358
92477
17032
53416
82948
25774
38857
24413
34072
04542
21999
13602 51851 46104
j
04734 i 59193
26384 1 58151
28728
45834 i 15398
60052
66566
89768
32832
37937
39972
74087
61230
14778
81536
35806
46557
50001
78797
86645
22178
06646
06912
41135
67658
14780
12659
61362 1 98947 i 96067
63904
22209
99547
76222 36086
26575
18912
28290
29880
06115
20655
09922
56873
66969
87589
94070
11398
22987
50490
59744
81249
78463
59516
08625
82271
35797
99730
20542
58727
25417
56307
98420
45766
66134
71500 ! 64568
81817
42607
84637 { 93161
40801
65424
05998
55536
18059
28168
44137
81607
04880
40836 ! 32427
25832
42878
80059
83785
92351
35648
59920
69774
41688
84855
02008
15475
48413
49518
46586
70002
69975 1 94884
80287
39911
55657
97473
56891
54328 ! 02349
81652 1 27195
88267
96189
14361
89286
69352
17247
48223
88916
30421
81825
01263
54613
44394 i 42880
210691 106341 12952
84903 i 42508
44947
11458
85590
90511
32307
05585 1 56941
18593 1 64952
91610 78188
33703 i 90322
271561 30613
20285 1 29975
74461 28551
63990 i 75601
44919105944
01915 I 92747
17752 35156
19500 1 25325
61666 99904
21524 15227
17012 64161
10367
32586
74952
89868
90707
40719
55157
64951
35749
58104
32812
96909 i 44592
18296 1 22851
07684 ! .36188
86679 1 50720
13300 87074
92259
84760
18510
94953
79666 i 95725
57102 1 80428
84584196096
75470 66520 34693
91402 42416
43808
78038
29841
33611
34952
29080
73708
56942
25555
89656
46565
70663
19661
47363
41151
31720
35931
48373
28865
46751
07844
25280
98253
90449
89618
78655 1 62028 i 76630
65855
30150
54262
37888
77919 | 88006
12777
48501
85963 1 03547
38917
09250 i 79656
83517 1 36103
88050
73211
42791
53389 | 20562 1 87338
21246
20103
04102
88863
72828
46634
14222
57375
04110
35509
77490
46880
77775
00102
06541
60697
56228
23728
45578 1 78547
14777 62730
22923 32261
20468
18062
45709
69348
66794
97809
59583
41546
51900
81788
92277
mw
A-3
-------
Table of Random Units
Line/Col.
51
52
53
54
55
56
57
58
59
90
91
92
63
64
85
98
97
85
99
70
71
72
73
74
75
78
77
78
79
30
31
82
33
84
35
38
87
38
80
90
91
92
93
94
95
98
97
98
90
100
(1)
16408
18629
73115
57491
30405
16831
96773
38035
31624
78019
03931
74428
09068
42238
16153
21457
21581
55612
44857
91340
91227
50001
65300
27504
37160
11508
37440
48615
30088
63798
82486
21886
60336
43937
97658
03290
79626
85836
18039
08362
79558
92608
23982
09915
50937
42488
48784
03237
88591
38534
(2)
81899
81953
35101
16703
33948
35006
20206
84202
76384
19474
33309
33278
00003
12428
08002
40742
57802
78005
(3)
04153
05520
47498
23167
23792
85900
42559
14349
17403
23632
57047
43972
20795
87025
28504
29820
02050
33197
(4)
53381
91962
87837
49323
14422
98275
78985
82674
53383
27880
74211
(5)
79401
04739
99016
45021
15059
32388
05300
66523
44167
47914
93445
10119189917
95452
14267
41744
98783
89728
33732
68000 I 99324 j 51281
84070
21190
38140
05224
96131
94861
70225
30383
70331
31223
64006
84848
32908
98782
48891
63175
01221
06488
68335
14367
15858
29088
82674
25835
98308
33300
78077
86273
45430
31482
01715
46940
31935
68321
72958
83044
30117
51111
08804
85022
42416
48583
99254
92431
07408
24010
89303
05418
03574
47539
81337
90827
04142
27072
40055
05908
28696
69882
63003
55417
52887
94964
81973
27022
92848
(6)
21438
13092
71060
33132
45799
52390
22164
44133
94488
02584
17381
15885
45454
20979 1 04508
81U5H
29400
17937
05810
84483
37949
84067
19924 72163
28600 181408
41575
80832
38351
54600
38329
58353
09785
67632
00060
53458
25560
18275
38082
17668
03129
06177
36478
16288
32534
67008
97901
62247
61657
93017
63282
91583
10573
00959
19444
04052
57015
21532
44180
43218
64297
13584
88355
07100
55758
07785
65851
12143
65848
15387
17075
12293
23395
69927
34136
31204
90816
14972
87288165680
65642
21840
37821
24813
60583
61023
05462
09538
30147
08819
18487
68400
53115
15765
30502
78128
50076
51674
59080
33041
92083
92237
78020
11977
48609
16764
12858
27698
02753
14186
76123
79180
36692
17349
90053
(7)
83035
97862
88824
12544
22716
16815
24369
00697
94758
(8) (9)
92350
36693
24822 94730
(10)
31238
06498
710131 18735(20286
41035(80780 45393
19792
99298
09983
82732
74353
38480
54224 35083 I 19687
35552
75366
37680 | 20801
92825
52872
09552
64535
74240
15035
47075
88902
39908
35970 | 19124
76554 131801
72152 ( 39339
05607
73823 ) 73144
88815
31355
56302
34537
42080
90307
79312 ! 93454
43907
35216
12151
25540
15283
14488
16553
91284
88682
51125
86084 i 29472
00033
33310
97403
16480
68878
80844
29891
06878 1 91903
48542
64482173923
65536
71946
62757
97161
32305
33091
21361
64128
26445
25786
21942
26759
79924
02510
32989
53412
66227
98204
14827
00821
50842
97526
40202
88298
89534
43772 | 39580
49071
05422
95348
17889
88482
42886
64818
62570
29789
54990
18611
86367
25861
26113
74014
09013
38358
93883
22235
80703
43834
43092
35275
90183
42627
38152
39782
13442
78682
97107
06116
48826
03264
25471
43042
98607
18740
45233
05184
17005
78675
11183
45340 j 61798
05174 1 07901
92520 { 33531
51202 i 88124
28123 1 05155
85205 1 41001
718001 15475
47348
21216
83325
20203
98442
88428
99447 168645
64708 00533
07832 41574
22478
11951
73373
34848
35071 99704
70428 75647
86654 70969
04098 1 73571
57308 j 55543
36600178408
76036 1 49199 1 43718
(11) (12)
59649191754
35090 1 04822
23153 I 72924
(13) -HI
T2772 02JM
86772 982S9
35165 43040
44812 12515198931 91202
98868130429170735 2S49*
73817
11052
63318
32523
41961 44437
91491 80383,197+4
29686 ( 03387 ' 59844
12814133072160332 9232J
34806 1 08930 1 85001 87820
' 1
68833
88970
25570 ! 38818 1 48020
74492 1 51805 9937S
79375 ( 97596 19296 1 68097
47689 ! 05974 I 52468 ! 16814
77510 70825 23725134191
95240 j 15957
16572108004
68995)43805 33388121597
88525 i 42786 | 05269 1 92532
93911 25650
89203
41867
34408
57202
94142
02330
84081
81651
68345
54339
80377
41870
59194
12535
95434
18534
08303
35078
34327
35398
17639
88732
88022
37543
76310
79725
80799
53203
06216
71795
14951
56087
94617
25299
74301
68938
12882173572
99533150501
91698 1 8508J
82790170925
23772 1 0789J
84387 34925
00275148230
93854159894
50245134971 52924
81073 49106179880
58881
35909
52889
52799
12133
98227
03862
58613
72811
15152
58408
82163
09443
56148
11601
88717
93872
76538
18098
95787
97548104379
12918 86537 1 92738 1 19836 1 51132
74818 1 48942
81250 54231
51275 i 8355*
28225135782
14645 33541
21824 1 19585
78095 | 50134
91511 i 75928
22717150585
55230 9344*
13281 1 4790S
60859175547
82558105250
34925 57031
35503185171
37890 4012S
28117 192J3
71255 84239
47625 1 88884
42579190730
46370 128877
257391 »«
A-4
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APPENDIX B
Chain of Custody
B-l
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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-2
-------
Collector Collector's Sample No.
Place of Collection
Date Sampled Time Sampled
Field Information
Figure B-l. Example of sample label (EPA, 1982)
B-3
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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-4
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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 (8i 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 B-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-5
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Collector's Sample No.
CHAIN OF CUSTODY RECORD
Location of Sampling: Producer Hauler Disposal Site
Other: __^
Sample
Shipper Name: ^_________
Address: __^
numberstreetcitystatezip
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. . , .
signature titleinclusive dates
2.
signature title inclusive dates
3.
signature title inclusive dates
Figure B-3. Example of chain of custody record (EPA 1982)
B-6
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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 practicableusually 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-7
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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
COLLECTOR'S
SAMPLE NO.
TYPE OF
SAMPLE*
state
zip
FIELD INFORMATION
Analysis Requested
Special Handling and/or Storage
PART II: LABORATORY SECTION**
Received by
Title
Date
Analysis Required
* 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-8
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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-9
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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-10
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APPENDIX C
Example Summary Sheets for
Analytical and Statistical Results
From Unsaturated Zone Monitoring
C-l
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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-2
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GENERAL INFORMATION
EPA ID:
Company Name:
Address:
Person to contact about data:
Telephone Number: ( )_
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-3
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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)
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).
2
Enter 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-4
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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
Hazardous Constituents or Principle Hazardous Constituents, 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).
C-5
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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
1
Hazardous Constituents or Principle Hazardous Constituents (PHCs), and any
other pertinent parameters (e.g., soil pH).
?
'Each 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).
If uniform area is greater than 5 ha., more than three composite samples are
necessary; therefore, table would have to be expanded in these cases.
i
Circled parameter means that are found to be statistically signif. increased
over background.
C-6
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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.
n
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).
q
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.
Circled parameter means that are found to be statistically signif. increased
over background.
C-7
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APPENDIX D
Regulations on Unsaturated Zone Monitoring
Federal Register, Volume 47, Number 143
July 26, 1982
D-l
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PREAMBLE DISCUSSION ON UNSATURATED ZONE MONITORING
8, Unsaturated Zone Monitoring
> Section 264.278). As indicated earlier,
the purpose of unsaturated zone
monitoring is 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
umt. 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 is
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
monitoring soil-pore liquid) on the active
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 methods can be used to avoid any
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
means that the owner or operator must
monitor for the hazardous constituents
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.
then EPA can be reasonably certain that
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 is a hazardous
constituent contained in-the waste
applied at a unit that is difficult to
degrade, transform or immobilize in the
treatment zone. The owner or operator
may ask the Regional Administrator to
establish PHCa at the unit if the owner
or operator can demonstrate to the
Regional Administrator's satis/action
that degradation, transformation or
immobilization of the PHCa 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
PHCa. 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
the PHCs give an early warning of the
failure of the treatment process.
Therefore, a PHC r-.ast be one of the
most mobile constituents in the
treatment zone. Second, a PHC must be
one of the most concentrated and
persistent constituents in the treatment
zone. This is to assure that the
constituent provides a reliable
indication of the success of treatment in
the treatment zone.
In the selection of principal hazardous
constituents, the Regional Administrator
will evaluate the results of waste
analyses, literature reviews, laboratory
tests, and field studies. Waste analyses
will be used to identify the hazardous
constituents in the waste. Information
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 for a 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
intended to complement one another.
D-2
-------
Soil-core monitoring will provide values will be based on one year of
information primarily on the movement quarterly sampling as in the detection
of "slower-moving" hazardous monitoring program. Since background
constituents (such as heavy metals), soil levels are not likely to change
whereas soil-pore liquid monitoring will significantly during such a time frame,
provide essential additional data on the today's rules allow that background soil
movement of fast-moving, highly soluble levels may be established following a
hazardous constituents that soil-core
monitoring may miss.
The general elements of the
unsarurated zone monitoring program
are patterned after those required for
ground-water monitoring in Subpart F.
As in the detection monitoring program,
the unsarurated 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 significant increases over
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 high. Therefore, the
statistical procedures used in the
unsarurated 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
VTLD.IO.) 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
§ 2MJS7(h}.
While EPA believes that the standard
for statistical procedures just described
should be adequate for most situations.
EPA intends to further analyze the
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 and
sampling and analysis procedures and
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, hi the
ground-water monitoring program.
background values are based on data
taken from upgradient monitoring wells, appropriateness of other statistical
Such a concept is not applicable to land procedures for unsaturaled zone
treatment units. Background values at monitoring. For example. EPA is
land treatment units are established by considering whether other factors that
sampling the soil and soil-pore liquid in might affect background levels of soil
a background plot. A background plot is pore-water quality should be
generally a segment of the soil near the specifically addressed in devising the
monitoring protocols. EPA specifically
asks for public comment on this issue.
Third, the unsarurated zone
monitoring program does not call for
measurements of the flow and direction
of ground water. The gradient in the
ground water is not relevant to
unaaturated zone monitoring and, thus,
such information is not necessary.
Fourth, the response to the detection
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
days, of a permit modification
application that sets 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 tune1.) 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.
of a statistically significant increase in
Subpart M differs from the response
statistical procedures that are somewhat required hi Subpart F. The results of
different than those used for detection unsaturated zone monitoring are to be
monitoring programs under Subpart F. In used in the modification of the operating
order to account for seasonal variations practices at the unit Thus, the required
in soil-pore liquid quality, background response is the submission, within 90
D-3
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REGULATIONS ON UNSATURATED ZONE MONITORING
§ 264.278 Unsaturatedzom monitoring.
An owner or operator subject to this
subpart must establish an unsaturated
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 § 2&t271{bV
(2) The Regional Administrator may
require monitoring for principal
hazardous constituents (PHCa) in lieu of
the constituents specified under
§ 284.271(b). PHCa-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 Admmistrator'wrll establish
PHCs if he finds, based on waste
analyses, treatment r'emonstrations, or
other data, that effective degradation.
transi'jnnation, or rmmobiiization of the
PHCi will aware treatment at at least
equivalent levels for the other
hazardoub constituents in the wastes.
(b) The owner or operator must inatafl
an imaaturated zone monitoring system
that includes soil monitoring using soil
cores and wit-pore liquid monitoring
using devices such a« lysHneter*. The
cnsaturated 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 sou-pore flquid quality and
the chemical make-up of soil that has
not been affected "by leakage from the
treatment zone; and
(2) Indicate the quality of soil-pore
liquid and the "chemical make-up of the
soil below the treatment zone.
(c) Tha owner or operator mast ~
establish a background-ratae fox each
hazardous constituemtto be monitored
under paragraph (a) of this section. The
permit will specify the background
values for each constituent or specify
the procedures to be used to calculate
the background values.
(1) Background son values may be
based on a one-time sampling at a
background plot having characteristics
similar to those of the treatment zone.
(2) Background sou-pore liquid values
must be based on at least quarterly
sampling for one year at a background
plot having r'nsmrttnimtim similar to
those of the treatment Tnng.
(3) The owner or operator must
express all background values in a form
necessary for tie determination of
statistically significant increases under
paragraph (f) of this aecrkm.
(4) In taking fmmpfaw used in the
determination of -all background values.
the owner or operator must use an
unsaturated zone monitoring system
that complies with paragraph (b)(l) of
this section.
(d) The owner or operator must
conduct soil monitoring and soil-pore
liquid monitoring immediately below the
treatment .zone. The Regional
Administrator will specify the frequency
and timing of soil and .sail-pare liquid
monitoring in the facility permit after
considering the frequency, timing, and
rate of waste application. an
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