vvEPA
               United States
               Environmental Protection
               Agency
               Hazardous Waste Engineering
               Research Laboratory
               Cincinnati OH 45268
               Office of Emergency and
               Remedial Response
               Washington DC 20460
               Superfund
Covers for
Uncontrolled
Hazardous Waste
Sites
EPA/540/2-85/002
September 1985

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    COVERS FOR UNCONTROLLED HAZARDOUS WASTE SITES
                          by
C. C. McAneny, P. G. Tucker, J. M. Morgan, C. R. Lee,
             M. F. Kelley, and R. C. Horz
   U.S. Army Engineer Waterways Experiment Station
            Vlcksburg, Mississippi  39180
                   Project Officer

                  Janet M. Houthoofd
           Land Pollution Control Division
   Hazardous Waste Engineering Research Laboratory
               Cincinnati, Ohio  45268
                  U.S. Environmental Protection Agency
                  Region V, Library
                  230 South Dearborn Street
                  Chicago,  Illinois  60604             >
   HAZARDOUS WASTE ENGINEERING RESEARCH LABORATORY
          OFFICE OF RESEARCH AND DEVELOPMENT
         U.S. ENVIRONMENTAL PROTECTION AGENCY
               CINCINNATI, OHIO  45268

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                                  NOTICE
     The development of this document has been funded,  wholly or in part,
by the United States Environmental  Protection Agency under Interagency
Agreement No. AD-96-F-2-A144 with the U.S. Army Engineer Waterways
Experiment Station.  It has been subject to the Agency's peer and
administrative review and has been  approved for publication as an EPA
document.

     Mention in this handbook of trade names or commercial  products does
not constitute endorsement or recommendation for their  use.
       UiS. Environmental Protection
                                    11

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                                 PREFACE
     This technical  handbook is one of a series of publications  being
issued to implement CERCLA, otherwise known as the Superfund law.   These
documents discuss technical matters involved in implementing the National
Contingency Plan (NCP) for dealing with releases of hazardous substances.

     This document is intended to provide information  and guidance  for
the benefit of cover designers and regulatory personnel  concerned with
cover installations at uncontrolled waste sites.  It is  not  intended to
replace the services of a qualified design engineer, nor does it address
every conceivable waste-site cover problem.  The carrying out of remedial
actions at uncontrolled waste sites is an evolving field, and experience
gained with actual  cover installations over the coming years will provide
increased knowledge and may well  lead to changes in some recommended
practices.

     Although this technical handbook is not meant to  address policy,
CERCLA actions should, as a matter of recent Agency policy,  comply  with
applicable or relevant standards  of other statutes unless one of five
exceptions applies in a limited number of instances (see the Federal
Register, February 12, 1985 Proposed Revision to the NCP, for discussion
of this policy and the five exceptions).  For covers at  Superfund sites,
this policy generally means that  the RCRA technical  requirements contained
in 40 CFR 264.310 should be met.

     The specific requirements under 40 CFR 264.310 are  presented here to
assist the user of the technical  handbook in the evaluation  of proposed
covers at uncontrolled hazardous  waste sites.  The regulatory requirements
(40 CFR 264.310) specify that final  cover be designed  and constructed to:

     (1)  Provide long-term minimization of migration  of liquids through
          the closed landfill.

     (2)  Function with minimum maintenance.

     (3)  Promote drainage and minimize erosion or abrasion  of the  cover.

     (4)  Accommodate settling and subsidence so that  the cover's integrity
          is maintained.

     (5)  Have a permeability less than or equal  to the  permeability of
          any bottom liner system or natural  subsoils  present.
                                      iii

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     Recommended guidance has been developed for meeting these five
regulatory requirements although alternative designs  could  also meet  the
five regulatory requirements.  The ability of alternative designs  to  meet
the five regulatory requirements would have to be demonstrated with more
detail than the recommended design.

     The RCRA guidance for covers specifies that the  cover  should  consist
of the following as minimum:

          Vegetated top cover
          Middle drainage layer
          Low permeability bottom layer
          -  ^20 mil  synthetic - upper component (may  be optional)
          -  >_ 2 ft clay layer - lower component

     Detailed guidance on each component is as follows:

     A)    Vegetated Top Cover

          o  minimum 24 in.  thick
          o  should support  vegetation that minimizes erosion  without
             continued maintenance
          o  planted with persistent  species - no roots  that will  penetrate
             beyond the vegetative and drainage layers
          o  top slope, after settling and subsidence,  of between  3-5% -
             if > 5% use USDA Universal  Soil  Loss Equation  to  demonstrate
             a soil  loss of  < 2.0 tons/acre/yr.
          o  surface drainage system  capable of conducting  runoff  across
             cap with no problems.

     B)    Middle Drainage Layer

          o  minimum 12 in.  thick
          o  saturated conductivity not less than lxlO~3  cm/sec
          o  bottom slope of  at least 2 percent
          o  designed to prevent clogging  - overlain by  a graded granular
             or synthetic fabric filter
          o  discharge flows  freely

          The granular or fabric filter is  used to prevent  plugging of
          the porous media with fine  earth  particles carried down  from the
          vegetated layer.

          To  prevent fluid from backing up  into  the drainage layer, the
          discharge  at the site should  flow freely (the edge of the unit
          should drain freely,  e.g.,  into  surface  runoff  ditch).

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C)   Low Permeability Bottom Layer

     -  upper component

        o  at least 20 mil  synthetic (may  be  optional)
        o  bedding layer at least 6  ft  thick  - no coarser than unified
           soil  classification system sand (sp)
        o  final  upper slope at least 2%
        o  be located wholly below the  average depth of frost
           penetration in the area of interest

     -  lower component

        o  at least 2 ft of soil  recompacted  to a saturated conductivity
           of not more than lxlO~7 cm/sec
        o  soil  emplaced in lifts not exceeding 6 inches before
           compaction.

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                                   ABSTRACT
     This Technical  Handbook provides guidance to the designer of cover sys-
tems for existing uncontrolled hazardous waste sites.   The Handbook also pre-
sents sources of technical  information to aid regulatory personnel in evalu-
ating cover designs.   A cover over an uncontrolled hazardous waste site acts
as a roof, deflects  precipitation, minimizes percolation and leachate forma-
tion, and thus prevents or minimizes future ground-water contamination.   To
estimate the amount  of leachate expected from a given cover design, it is
necessary to perform a water-balance analysis.

     A cover design  is site-specific and requires a good site investigation
report, which is normally prepared as part of the Hazardous Substance Response
process.  A cover system can be properly designed only after decisions re-
garding certain basic considerations, such as design life of the system and
future use of the site, have been made.

     The majority of the materials used in any cover system are likely to be
soils, which are best classified by the Unified Soil Classification System
(USCS).  Soil properties important in cover applications include gradation,
Atterberg Limits, density,  and permeability.  Standardized tests for these and
other soil properties are described and/or technical manuals referenced.
Soils may be stabilized or modified by the use of soil additives.

     Several types of materials other than soils may be used in cover systems.
Some parts of a cover system require impermeable materials; other parts re-
quire permeable materials.   Materials for impermeable applications include
asphalt, cement, and synthetic membranes known as "geomembranes."  Materials
for permeable applications include various waste or residual substances from
industrial processes, drainage supplies such as pipes and tiles, and synthetic
fabrics known as "geotextiles."  Tests and criteria are available for judging
the suitability of all these materials.

     To meet the requirements for various functions and attributes, the most
efficient cover system is composed of layers.  If gases are produced by or-
ganic decay within the wastes, a gas-permeable layer above the wastes, with
suitable venting mechanisms, may be required.  One or more permeable filter
layers is necessary where materials of contrasting gradation are placed in
direct contact with one another in the presence of water; otherwise fines may
migrate and block the pores of the coarser material.  A foundation or buffer
layer is necessary to serve as a platform on which to build the rest of the
system.  The hydraulic barrier layer may be composed of either relatively
impervious natural soils, amended soils, or a geomembrane.  The drainage layer
intercepts percolating water and provides a path for it to a disposal outlet.
A biotic barrier layer stops animals and plant roots from penetrating and

                                      vi

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thereby disrupting the hydraulic barrier.  The surface layer must provide for
vegetative support, stabilize the surface against erosion, aid in dewatering
the cover through evapotranspiration, and provide an aesthetically pleasing
appearance.  An effective surface water management plan is essential to con-
trol surface runoff.  Elements of this plan are discussed.

     During construction, the site preparation phase involves establishment of
site security, clearing and grubbing operations, and establishment of support
facilities, access roads, and soil stockpiles.  Equipment used during the sub-
sequent cover construction phase includes both conventional earth moving ma-
chinery and specialized equipment such as may be required in geomembrane in-
stallation.  During the site closure phase, institutional care and maintenance
are performed and the site is monitored to ascertain whether the cover system
is performing as intended.

     Quality control and assurance for cover system installation depends on an
effective construction organization, appropriate observation, sampling and
testing methods, and good documentation.   There should be good communication
between the design, construction, and inspection groups,  and clearly defined
responsibilities for each.  Observations  are made continuously of site prepa-
ration, excavation, foundation preparation, barrier installation, drain in-
stallation, and other activities.  Sampling of installed  cover materials
should be done on a planned,  systematic basis.  From the  many test methods
available, quality control test methods should be chosen  on a site-specific
basis, considering the merits and limitations of each method.   Complete docu-
mentation is the backbone of any effective quality assurance program.

     Two existing cover installations are presented as examples.
                                      vn

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                                  CONTENTS
                                                                          Page

PREFACE	        iii
ABSTRACT	         vi
LIST OF FIGURES	       xiii
LIST OF TABLES	        xlx
ACKNOWLEDGMENTS  	       xxiv

1.0   INTRODUCTION	      1-1
1.1   Background	      1-1
1.2   Purpose and Scope	      1-2
1.3   Cover Functions and Attributes 	      1-4
1.4   Different Types of Waste Sites 	      1-6
1.5   Concept of Cover as a Roof	      1-7
1.6   Ideal Versus Real Covers	      1-9
1.7   The Hydro!ogic Cycle as Applied to Covers	      1-9

2.0   SITE CHARACTERIZATION	      2-1
2.1   Data Requirements	      2-1
2.2   Data Sources	      2-2
      2.2.1   Topography	      2-2
      2.2.2   Soils	      2-3
      2.2.3   Geology	      2-3
      2.2.4   Hydrology and Geohydrology 	      2-4
      2.2.5   Aerial Photographs 	      2-4
      2.2.6   Cultural  Features  	      2-4
      2.2.7   Vegetation Data	      2-5
      2.2.8   Climatic  Data	      2-5
      2.2.9   Waste Characteristics  	      2-6
2.3   Specific Site Investigations 	      2-7

3.0   MATERIALS USED IN COVER SYSTEMS	      3-1
3.1   Introduction	      3-1
3.2   Soils as Cover Materials	      3-1
      3.2.1   General Soil  Factors	      3-2
      3.2.2   Common Soil Terms	      3-4
      3.2.3   Soil  Properties	      3-5
      3.2.4   Soil  Classification	      3-8
              3.2.4.1   Agricultural Classification  	      3-9
              3.2.4.2   Unified Soil Classification System 	      3-10
              3.2.4.3   AASHTO Classification  	      3-12
                                       ix

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                             CONTENTS (continued)
      3.2.5   Soil Tests	      3-12
              3.2.5.1   Gradation  	      3-16
              3.2.5.2   Atterberg Limits 	      3-19
              3.2.5.3   Water Content and Specific Gravity 	      3-21
              3.2.5.4   Density  	      3-21
              3.2.5.5   Strength 	      3-26
              3.2.5.6   Consolidation  	      3-26
              3.2.5.7   Permeability 	      3-29
              3.2.5.8   Shrink/Swell  Behavior; Activity  	      3-36
              3.2.5.9   Dispersivity 	      3-37
              3.2.5.10  Other Soil  Properties and Tests  	      3-38
      3.2.6   Engineering Characteristics of Soil Types  	      3-39
3.3   Soil Additives	      3-39
      3.3.1   Common Soil Additives and Their Applications 	      3-44
              3.3.1.1   Soil Stabilization 	      3-44
              3.3.1.2   Permeability Reduction 	      3-47
      3.3.2   Soils Suitable for Stabilization/Modification  ....      3-47
      3.3.3   Soil Blending	      3-48
3.4   Nonsoil Materials  	      3-48
      3.4.1   General	      3-48
      3.4.2   Impermeable Materials  	      3-48
              3.4.2.1   Asphalt  	      3-48
              3.4.2.2   Synthetic Membranes ("Geomembranes") ....      3-52
              3.4.2.3   Concrete and Cement  	      3-56
      3.4.3   Permeable Materials  	      3-66
              3.4.3.1   Organic Residual Materials 	      3-66
              3.4.3.2   Residual Materials from the Mining
                        and Metallurgical Industries 	      3-66
              3.4.3.3   Fly Ash	      3-67
              3.4.3.4   Other Residual  Materials 	      3-69
              3.4.3.5   Pipes and Tiles  	      3-69
              3.4.3.6   Geotextiles  	      3-71

4.0   DESIGN OF A COVER SYSTEM	      4-1
4.1   Introduction	      4-1
      4.1.1   Basic Considerations  	      4-1
      4.1.2   Structure of a Cover  System	      4-2
      4.1.3   Design Procedure 	      4-5
4.2   Infiltration and Percolation; the Water Balance  	      4-8
      4.2.1   General Water Movement Patterns in
              Waste Site Areas	      4-8
      4.2.2   Cover as a Leaky Roof	      4-14
      4.2.3   Precipitation	      4-14
      4.2.4   Runoff	      4-16
              4.2.4.1   General  	      4-16
              4.2.4.2   Runoff Coefficients  	      4-17

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                             CONTENTS (continued)
              4.2.4.3   The Rational Method  	      4-17
              4.2.4.4   The SCS Curve Number Method  	      4-20
      4.2.5   Infiltration	      4-22
              4.2.5.1   General  	      4-22
              4.2.5.2   Infiltration Velocity,  Infiltration
                        Capacity, and Infiltration Rate	      4-25
              4.2.5.3   Factors Affecting Infiltration 	      4-25
              4.2.5.4   Modeling the Infiltration Process  	      4-26
              4.2.5.5   Measurement of Infiltration  	      4-31
              4.2.5.6   Design Implications  	      4-31
      4.2.6   Evapotranspiration 	      4-32
              4.2.6.1   Basic Principles and Nomenclature  	      4-32
              4.2.6.2   Estimating Evapotranspiration  	      4-33
      4.2.7   Methods of Water-Balance Analysis   	      4-35
              4.2.7.1   A Manual Water-Balance  Method  	      4-35
              4.2.7.2   The HELP Model	      4-37
              4.2.7.3   Some General Comments on
                        Water-Balance Methods  	      4-43
4.3   Gas Control	,	      4-44
      4.3.1   Gas Generation	      4-44
      4.3.2   Vapors	      4-45
      4.3.3   Gas Treatment and Control	      4-45
4.4   Filter Layer(s)	      4-51
      4.4.1   General	      4-51
      4.4.2   Granular Filters 	      4-52
      4.4.3   Geotextiles	      4-53
4.5   Foundation Layer 	      4-56
      4.5.1   Function of Foundation Layer 	      4-56
      4.5.2   Materials	      4-59
      4.5.3   Compaction	      4-59
      4.5.4   Soil Stabilization	      4-62
              4.5.4.1   Cement Stabilization 	      4-64
              4.5.4.2   Lime or Lime-Based Stabilization 	      4-68
              4.5.4.3   Bituminous Stabilization 	      4-68
4.6   Hydraulic Barrier Layer  	      4-69
      4.6.1   General	      4-69
      4.6.2   Failure Mechanisms 	      4-70
              4.6.2.1   Chemical 	      4-70
              4.6.2.2   Mechanical 	      4-70
              4.6.2.3   Environmental  	      4-73
      4.6.3   Barrier Materials  	      4-74
              4.6.3.1   Soils  	      4-74
              4.6.3.2   Amended Soils  	      4-74
              4.6.3.3   Asphalt  	      4-77
              4.6.3.4   Geomembranes 	      4-82
                                       XI

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                             CONTENTS (continued)
4.7   Drainage Layer	     4-84
      4.7.1   General Principles 	     4-84
      4.7.2   Subsurface Drainage Design 	     4-87
      4.7.3   Collectors	     4-90
      4.7.4   Agricultural Drain Tiles 	     4-90
      4.7.5   Exit Design	     4-97
4.8   Biotic Barrier	     4-97
4.9   Surface (Vegetative) Layer 	     4-99
      4.9.1   Desirable Functions of Vegetation  	     4-100
      4.9.2   Soil Considerations	     4-101
              4.9.2.1   Grain Size	     4-102
              4.9.2.2   Soil pH	     4-102
              4.9.2.3   Organic Matter and Nutrients 	     4-102
              4.9.2.4   Thickness of Soil Layer  	     4-105
      4.9.3   Appropriate Vegetation 	     4-105
              4.9.3.1   Criteria for Selecting Grasses
                        and Forbs	     4-106
              4.9.3.2   Criteria for Selecting Shrubs
                        and Trees	     4-116
              4.9.3.3   Breeding and Selecting Plants to
                        Tolerate Stress  	     4-118
              4.9.3.4   Source of Seed	     4-118
              4.9.3.5   Use of Single Species Versus Mixtures  .  .  .     4-118
              4.9.3.6   Use of Adapted Native Versus
                        Introduced Plant Species 	     4-119
              4.9.3.7   Undesirable Species  	     4-119
              4.9.3.8   Other Selection Factors  	     4-119
      4.9.4   Establishment and Maintenance of Vegetation  	     4-120
              4.9.4.1   Time of Seeding and Planting	     4-120
              4.9.4.2   Irrigation as a Temporary Measure  	     4-121
              4.9.4.3   Methods of Seeding and Planting  	     4-121
              4.9.4.4   Mulching and Chemical Stabilization  ....     4-123
              4.9.4.5   Organic Mulches  	     4-124
              4.9.4.6   Chemical Mulches and Stabilizers 	     4-132
              4.9.4.7   Nonbiodegradable Mulches 	     4-132
              4.9.4.8   Erosion-Control Fabrics  	     4-136
              4.9.4.9   Vegetative Maintenance 	     4-137
      4.9.5   Nonvegetative Measures 	     4-138
              4.9.5.1   Stone Stabilization  	     4-138
              4.9.5.2   Soil-Cement  	     4-139
      4.9.6   Maintenance of Stabilization Measures  	     4-140
4.10  Surface Water Management 	     4-140
      4.10.1  General   	     4-140
      4.10.2  Surface Water Management Program (SWMP)  	     4-141
              4.10.2.1  Land Grading	     4-142
              4.10.2.2  Waterways  	     4-146

                                     xii

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                             CONTENTS (continued)
4.11

5.0
5.1
5.2
6.4
6.5
6.6

6.7
         4.10.2.3
         4.10.2.4
         4.10.2.5
 Frost Action .  .
                        Diversion Structures
                        Check Dams 	
                        Outlet Structures  .
 CONSTRUCTION 	
 Operational and Construction Guidance
 Phases of Cover Construction 	
        2.1
        2.2
      5.2.3
         Site-Preparation Phase 	
         Cover-Construction Phase 	
         5.2.2.1   Planning and Scheduling
         5.2.2.2   Equipment  	
         Site Closure Phase 	
5.3   General and Special Construction Operations
      5.3.1
      5.3.2
      5.3.3
      5.3.4
         Mixing and Placement of Soil-Cement
         Compaction of Foundation Layer .  .  .
         Placement of Asphalt Concrete  .  .  .
         Installation of Polymeric Barriers  .
      CONSTRUCTION QUALITY CONTROL 	
      Construction Organization  	
      Quality-Assurance/Quality-Control  of Construction
      Quality-Control  Observations 	
         Site Preparation
         Excavation 	
         Foundation Preparation 	
         Compacted Earthfill  	
         Liner-Type Materials and Geotextiles .
         Hydraulic Collector System 	
Quality-Control Sampling  	
 6.4.1   Frequency of Sampling and Testing  .  .
 6.4.2   Types of Sampling  	
 6.4.3   Selection of Sample Size 	
 Quality-Control Tests  	
 Geomembrane/Geotextile Independent-Laboratory
 Verification Tests 	
Quality-Assurance Program 	
APPENDIX A:   REFERENCES AND BIBLIOGRAPHY
APPENDIX B:   CASE HISTORIES  ....
B.I   Sylvester Hazardous Waste Site
B.2   Kin-Buc Landfill 	
APPENDIX C:   COSTS
4-149
4-155
4-159
4-159

5-1
5-1
5-2
5-2
5-4
5-4
5-6
5-21
5-21
5-21
5-24
5-25
5-25

6-1
6-1
6-2
6-2
6-2
6-3
6-4
6-4
6-6
6-7
6-8
6-8
6-11
6-11
6-12

6-12
6-14

A-l

B-l
B-l
B-10

C-l
                                     xiii

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                             CONTENTS (continued)
                                                                         Paqe
APPENDIX D:  SYMBOLS, ABBREVIATIONS, AND ACRONYMS; METRIC
             CONVERSION	     D-l

APPENDIX E:  GLOSSARY  	     E-l

APPENDIX F:  LAWS AND REGULATIONS	     F-l

APPENDIX G:  QUALITY-CONTROL TEST METHODS  	     G-l

APPENDIX H:  WATERWAY AND OUTLET STRUCTURE
             DESIGN AND CONSTRUCTION 	     H-l

APPENDIX J:  INFORMATION SOURCES 	     J-l

INDEX	     1-1


                                LIST OF FIGURES


Number                                                                   Page

1-1       Elements of Hydro!ogic Cycle 	     1-10

3-1       Flocculent Structure of Sensitive Clay Suggested
          by A.  Casagrande (1932)	     3-3

3-2       Diagrammatic Representation of Soil as a Three-Phase
          System, Showing Weight and Volume Notations and
          Relationships  	     3-5

3-3       Particle Size Limits of Soil Fractions According
          to Several Classification Systems  	     3-9

3-4       Guide for Textural Classification of Soil Used
          by U.  S. Department of Agriculture	     3-10

3-5       The Unified Soil  Classification System 	     3-11

3-6       Comparison of USCS and USDA Soil Terminology	     3-13

3-7       Gradation Curves of Some Sanitary-Landfill
          Cover Soils	     3-18

3-8       Apparatus for Determination of Liquid Limit  	     3-20

3-9       Typical Compaction (Moisture-Density) Test Result  ....     3-23

                                       xiv

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                          LIST OF FIGURES (continued)


Number                                                                   Page

3-10      Relation Between Laboratory Test Results and Standard
          Contract Specifications for Compaction 	      3-24

3-11      Field and Laboratory Compaction Curves for Soils Placed
          in Dam Embankments of Three USER Projects	      3-25

3-12      Time Curves for a Typical Load Increment in a Laboratory
          Consolidation Test:   (a) for Sand, and (b) for Clay  .  .  .      3-28

3-13      Sketch Showing Relation Between Darcy ("Superficial")
          Velocity  V  and Seepage Velocity  V         	      3-30
                                              seepage

3-14      Effect of Degree of Saturation on Permeability 	      3-33

3-15      Chart for Selecting Soil-Stabilizing Additives 	      3-45

3-16      Typical Adhesive/Solvent Seams 	      3-57

3-17      Heat Welding	      3-58

3-18      Extrusion Welding System - Top-Laid  	      3-59

3-19      Extrusion Welding System - Intermembrane 	      3-60

3-20      Seam Failure Modes	      3-61

4-1       Structure of a Cover System	      4-3

4-2       General Decision Flowsheet for Cover Design
          Formulation	      4-6

4-3       Review of Potential  Problems 	      4-7

4-4       Simplified Soil/Water Profile  	      4-9

4-5       Typical Soil-Water Relationships 	      4-10

4-6       Schematic Three-Layer Cover System 	      4-15

4-7       Runoff vs.  Rainfall  for Various SCS Curve Numbers  ....      4-24

4-8       Idealized Relationship Between Infiltration
          Capacity and Time	      4-27

4-9       Relationship Between Infiltration Rate and Time
          for Various Rates of Water Supply  	      4-27
                                      xv

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                          LIST OF FIGURES (continued)


Number                                                                   Page

4-10      Soil Profile as Infiltration Occurs	      4-29

4-11      Typical Landfill Profile 	      4-40

4-12      Gas Control Barriers	      4-47

4-13      Gas Extraction Well Design	      4-49

4-14      Moisture Control in Collection Header  	      4-50

4-15      Granular Filter Example  	      4-54

4-16      Typical Filter Materials 	      4-55

4-17      Series of Filter Layers	      4-55

4-18      Random Dumping	      4-58

4-19      Group Index for Soil-Cement Mixtures 	      4-66

4-20      Types of Mechanical Failures 	      4-72

4-21      Biotic Intrusion 	      4-73

4-22      Asphalt Distributor  	      4-81

4-23      Joints for Asphalt Concrete  	      4-82

4-24      Drainage Layer Schematic 	      4-85

4-25      Collection/Transport System Patterns 	      4-86

4-26      Drainage Blanket Elements  	      4-88

4-27      Analysis of Drainage Layer Performance 	      4-89

4-28      Characteristics of Clean Coarse-Grained
          Drainage Material  	      4-89

4-29      Gravel Collector Characteristics 	      4-91

4-30      Subsurface Drain Capacity,  n = 0.025  	      4-92

4-31      Airfield Drainage Nomograph for Computing Required
          Size of Circular Drain, Flowing Full,  n = 0.013
          and  n = 0.024	      4-93
                                      xvi

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                          LIST OF FIGURES (continued)


Number                                                                   Page

4-32      Methods of Placing Subsurface Drains 	     4-96

4-33      Small-Animal Guards  	     4-97

4-34      Toe Drain	     4-98

4-35      Plant Growth Regions of the Arid and Semiarid Areas
          of the Western United States	     4-107

4-36      Plant Growth of the United States for the Humid
          and Subhumid Climates  	     4-108

4-37      Influence of Slope on Revegetation 	     4-124

4-38      "Enkamat" Installed on Slopes  	     4-136

4-39      Slope with Reverse-Slope Bench 	     4-142

4-40      Maximum Allowable Overland Flow Distance 	     4-143

4-41      Typical Section of Serrated Cut Slope  	     4-146

4-42      Typical Diversion Ditch or Swale 	     4-149

4-43      Diversion Dike or Berm	     4-150

4-44      Combination Diversion  	     4-151

4-45      Log Check Dam - Type 1	     4-156

4-46      Log Check Dam - Type 3	     4-157

4-47      Rock Check Dam	     4-158

4-48      Spacing Between Check Dams	     4-158

5-1       Simplified Site Layout Showing Typical
          Construction Features  	     5-3

5-2       Sequencing of Layers During Cover Construction 	     5-5

5-3       Direction of Construction   	     5-5

5-4       Backhoes	     5-8

5-5       Power Shovel  and Dragline	     5-9
                                     xvii

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                          LIST OF FIGURES (continued)






Number                                                                   Page



5-6       Conveyor-Type Excavator  	      5-10



5-7       Dozers	      5-11



5-8       Scrapers	      5-12



5-9       Front-End Loaders  	      5-13



5-10      Sheepsfoot Rollers 	      5-14



5-11      Vibratory Steel-Wheel Drum Roller  	      5-15



5-12      Rubber-Tired Rollers 	      5-16



5-13      Landfill Compactor 	      5-18



5-14      Trencher	      5-19



5-15      Motor Grader	      5-20



5-16      Stair-Step Configuration 	      5-23



5-17      Asphalt Paving Machine 	      5-25



5-18      Spreading Polymeric Sheeting 	      5-26



5-19      Sheeting Aligned and Weighted  	      5-27



5-20      Inspection of Seams	      5-28



5-21      Cover Applied over Geomembrane 	      5-29



5-22      Geomembrane Field Stresses 	      5-31



5-23      Expansion-Contraction Phenomenon 	      5-32



5-24      Anchoring Details  	      5-33



5-25      Wind Cowl  	      5-34



B-l       Cap Detail, Sylvester Site	      B-3



B-2       Detail of Membrane Cap at Slurry Wall, Sylvester Site  .  .      B-3



B-3       Gas Vent Detail, Sylvester Site	      B-4



B-4       Detail of Seal of Membrane Cap Around Pipe	      B-4




                                     xviii

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                           LIST OF  FIGURES  (continued)


 Number                                                                    Page

 B-5        Geomembrane  Being  Laid at  Sylvester  Hazardous  Waste
           Site,  Strip  Width  is 22.5  feet,  Thickness  40 mils,
           Material  HOPE	      B-5

 B-6        Gas  Vent  Pipes  Protruding  Through  3-ft-Thick Layer
           of Soil Placed  over  Geomembrane, Sylvester Hazardous
           Waste  Site	      B-5

 B-7        Geotextile Laid over Slurry Wall for Reinforcement ....      B-6

 B-8        Plan View of Kin-Buc Landfill, Showing  Drainage  System  .  .      B-ll

 B-9        Edge of Top  Area,  Ditch  and Berm,  Kin-Buc  Landfill ....      B-12

 B-10       Downchute Section, Kin-Buc Landfill   	      B-12

 B-ll       Cover  Soil Section,  Top  Area, Kin-Buc Landfill 	      B-13

 B-12       Cover  Soil Section,  Side Slope Area,  Kin-Buc Landfill   .  .      B-13

 B-13       Gas  Vent  Detail, Kin-Buc Landfill	      B-14

 B-14       Grassed Channel  Section, Kin-Buc Landfill  	      B-15

 B-15       Side-Hill Ditch  and  Berm, Kin-Buc  Landfill 	      B-15

 B-16       Downchute at One Corner of Kin-Buc Landfill  	      B-16

 B-17       Rill  Erosion in  Side Slopes, Kin-Buc Landfill	      B-16

 H-l        Manning's Roughness  Coefficient n  Related to Velocity
           Times Hydraulic  Radius and Vegetal  Retardance  	      H-3

 H-2        Manning's Roughness  Coefficient  n   for
           Riprap-Lined Channels  	      H-14

 H-3        Riprap at Bends	      H-18

 H-4        P/r Ratio for Trapezoidal Channels	      H-18

H-5       Median Riprap Diameter for Straight Trapezoidal
          Channels	     H-19

H-6       Riprap Size Correction Factor for Flow in
          Channel Bends  	     H-20

H-7       Maximum Riprap  Side Slope with Respect to Riprap  Size  . .     H-20


                                     xix

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                          LIST OF FIGURES (continued)
Number
Paqe
H-8       Median Riprap Diameter for Straight Triangular
          Channels	      H-21

H-9       Pipe Outlet Conditions	      H-25

H-10      Design of Outlet Protection - Minimum Tailwater
          Condition (Tw < 0.5 diam.)	      H-27

H-ll      Design of Outlet Protection - Maximum Tailwater
          Condition (Tw > 0.5 diam.)	      H-28

H-12      Paved Channel Outlet 	      H-29

H-13      Paved Chute or Flume	      H-31

H-14      Pipe Slope Drain (Rigid)	      H-34

H-15      Pipe Slope Drain (Flexible)  	      H-35



                                LIST OF TABLES


Number                                                                   Page

1-1       Possible Remedial Methods  	      1-3

1-2       Cover Functions and Attributes 	      1-5

2-1       Selected Publications of the National Climatic Center  .  .      2-6

2-2       Sources of Guidance for Site Investigations	      2-7

3-1       Usual Correspondence Between USCS and USDA
          Soil Designations	      3-14

3-2       AASHTO Classification of Soils and Soil-Aggregate
          Mixtures	      3-15

3-3       Manual Designations of Selected Engineering Soil Tests .  .      3-17

3-4       Standard Permeability Tests  	      3-35

3-5       Permeability Conversion Factors  	      3-36

3-6       Activities of Various Minerals 	      3-37

                                       XX

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                           LIST OF TABLES  (continued)


Number                                                                   Page

3-7       Characteristics  of USCS Soil Groups Pertinent to
          Roads and Airfields	     3-40

3-8       Engineering Use  Chart for USCS  Soil Groups, with
          Emphasis on Earth Dams and Related Features  	     3-41

3-9       Ranking of Unified-System (USCS) Soil Groups with
          Regard to Cover-Related Engineering Behavior 	     3-42

3-10      Average Properties of Soils  	     3-43

3-11      Guide for Selecting a Stabilizing Additive 	     3-46

3-12      Advantages/Disadvantages of Various Forms
          of Asphalt Construction  	     3-50

3-13      Commonly Used Polymeric Membranes  	     3-53

3-14      Average Cement Requirements for Exposed Soil-Cement
          Slope Protection	     3-64

3-15      Representative Laboratory Tests for Soil-Cement
          Design Parameters  	     3-64

3-16      Permeability of Cement-Treated Soils 	     3-65

3-17      Drainage-Materials Specifications  	     3-70

3-18      Description of Geotextile Functions  	     3-72

3-19      Applications and Controlling Function of Geotextiles .  .  .     3-73

3-20      Important Criteria and Properties for Evaluating
          a Geotextile	     3-74

3-21      Geotextiles Used for Various Practical  Applications  .  .  .     3-76

4-1       Typical  Soil  Characteristics 	     4-11

4-2       Typical  Runoff Coefficients  	     4-19

4-3       Runoff Coefficients for Agricultural  Lands 	     4-20

4-4       Classification of Soils by Hydrologic Characteristics  .  .     4-22

4-5       Runoff Curve Numbers for Antecedent Moisture
          Condition II	     4-23

                                      xx i

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                          LIST OF TABLES (continued)


Number                                                                   Page

4-6       Corresponding Curve Numbers for Antecedent Moisture
          Conditions I, II, and III	      4-24

4-7       Typical  f.  Values for Bare Soils	      4-30

4-8       Vegetation Cover Factors 	      4-30

4-9       Granular Filter Design Considerations  	      4-56

4-10      Geotextile Filter Considerations 	      4-57

4-11      Typical Properties of Compacted Materials  	      4-63

4-12      Tests for Stabilized Soils 	      4-64

4-13      Estimated Cement Requirements for Various Soil Types .  .  .      4-65

4-14      Average Cement Requirements for Granular and
          Sandy Soils	      4-65

4-15      Average Cement Requirements for Silty and
          Clayey Soils 	      4-67

4-16      Durability Requirements  	      4-67

4-17      Recommended Gradations for Bituminous-Stabilized
          Subgrade Materials 	      4-68

4-18      Asphalt Aggregate Guidance 	      4-69

4-19      Chemical Compatibility Guidance  	      4-71

4-20      Soil Permeability Guidance	      4-75

4-21      Soil Conservation Service Recommended Sodium Bentonite
          Application  Rate for Farm Ponds	      4-75

4-22      Permeability of  Cement-Treated Soils 	      4-78

4-23      Requirements for Asphalt for  Use in Waterproof
          Membrane Construction   	     4-78

4-24      Selection  of Emulsified Asphalt Amount  	     4-79

4-25      Asphalt Testing  Guidance  	     4-80

4-26      Mix  Compositions for Formed-in-Place Asphalt  Linings . . .     4-81

                                      xx ii

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                          LIST OF TABLES (continued)


Number                                                                   Page

4-27      Guidance for Subsurface Drainage Systems 	     4-94

4-28      Allowable Trapezoidal Grooves for Bedding Corrugated
          Polyethylene Drainage Tubing 	     4-95

4-29      Guidance for Tile Specifications	     4-98

4-30      Relative Levels of Organic Matter and Major Nutrients
          in Soils	     4-104

4-31      Characteristics and Suitability of Legumes Recommended
          for Vegetative Surface Cover 	     4-109

4-32      Characteristics and Suitability of Grasses Recommended
          for Establishing Ground Cover  	     4-110

4-33      Guide to Short-Term Mulch Materials, Rates, and Uses .  .  .     4-125

4-34      Mulch Anchoring Guide  	     4-127

4-35      Comparison of Water-Dispersible Mulches and Stabilizers
          for Initial Land Restoration	     4-129

4-36      Summary of Methods and Costs of Hydroseeding and
          Hydromulching in California  	     4-130

4-37      Summary of Chemical Binders and Tacks  	     4-133

4-38      Application Rates for Selected Binders and Tacks 	     4-134

4-39      Guide to Long-term Nonbiodegradable Mulches  	     4-135

4-40      Maintenance Practices for Surface Stabilization
          Measures	     4-139

4-41      Land Grading Design Criteria and Considerations  	     4-144

4-42      Guidance for Grading Construction Specifications 	     4-145

4-43      Typical  Channel  Cross-Sectional  Characteristics  	     4-148

4-44      Design Criteria for Diversion Structures 	     4-152

4-45      Construction Specification Guidance for
          Diversion Structures 	     4-153
                                     xx i i i

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                          LIST OF TABLES (continued)

Number                                                                   Page
4-46      Examples of Permissible Velocities for
          Stable Diversions  	      4-154
5-1       Applicability of Equipment Types to Various
          Operational Functions  	      5-7
5-2       Compaction Equipment Guidance  	      5-17
5-3       Partial List of Construction Operations and Functions  .  .      5-22
6-1       Quality-Control Test Methods 	      6-13
B-l       Bid Tabulation for Cap and Containment Wall Construction
          at the Sylvester Site, Nashua, New Hampshire 	      B-7
C-l       Capital and O&M Components Which Contribute to
          Unit Operations	      C-2
C-2       Average U. S.  Low and High Costs of Unit Operations
          for Medium-Sized Sites - Metric Units  	      C-3
C-3       Landfill Capital Cost Components - Metric Units  	      C-5
C-4       Landfill O&M Cost Components - Metric Units	      C-10
C-5       Surface Impoundment Capital Cost Components -
          Metric Units 	      C-ll
C-6       Surface Impoundment O&M Cost Components -
          Metric Units 	      C-14
D-l       Metric Conversion Table  	      D-10
H-l       Roughness Coefficient (n) for Various Channel Linings  .  .      H-2
H-2       Classification of Vegetal Cover in Waterways Based on
          Degree of Flow Retardance by the Vegetation	      H-4
H-3       Permissible Velocities for Vegetated Channels  	      H-5
H-4       Parabolic Waterway Design for Grade 5.0 Percent  	      H-6
H-5       Trapezoidal Channel Design for Grade 2.0 Percent 	      H-7
H-6       General Design Criteria for Riprap-Lined Channels  ....      H-14
H-7       Construction Specification Guidance for
          Channel Riprap 	      H-15
H-8       Riprap Designation Examples  	      H-16
H-9       Design Criteria for Filter Blankets  	      H-17
H-10      Bottom Widths and Maximum Drainage Areas 	      H-32
H-ll      Size of Pipe/Tubing	      H-33
                                     XXIV

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                             ACKNOWLEDGMENTS
     This handbook was prepared by personnel  of the U.S.  Army Engineer
Waterways Experiment Station (WES), Vicksburg, Mississippi.   The WES
Project Manager and principal  author was Mr.  Colin C.  McAneny, Geologist,
Engineering Geology and Rock Mechanics Division, Geotechnical Laboratory
(EGRMD, GL), WES.  Contributing authors included Mr. Patrick G.  Tucker,
Civil Engineer, Soil Mechanics Division (SMD), GL; Dr. Joe M. Morgan,
Research Civil Engineer, Environmental Engineering Division, Environmental
Laboratory (EED, EL); Dr. Charles R. Lee, Research Soil Scientist,  Ecosystem
Research and Simulation Division (ERSD), EL;  CPT Michael  F.  Kelley,  CE,
SMD, GL; and Mr. Raymond C. Horz, Civil Engineer, SMD, GL.  The handbook
was prepared under the supervision of Mr. John H. Shamburger, Chief,
Engineering Geology Applications Group, EGRMD, GL, and was critically
reviewed by Dr. Paul F. Hadala, Assistant Chief, GL.  The index was
prepared by Ms. Alfrieda S. Clark and Ms. Katherine M. Kennedy,  Special
Projects Branch, Technical  Information Center.

     EPA Project Officers during the period of the preparation and  review
of this handbook were Ms. Janet M. Houthoofd and Mr. Robert  E. Landreth.

     Numerous other individuals made valuable contributions  to the  final
version of this handbook.  The constructive critical reviews by  EPA-retained
peer reviewers Dr. Gordon P. Boutwell, Jr.» and Dr. Kirk  W.  Brown materially
improved numerous technical sections.  Helpful reviews were  also made  by
Mr. Robert P. Hartley, EPA HWERL, and Ms. Ann Tate, EPA CERI.  Messrs.
S. Paul Miller and G. Britt Mitchell and Dr.  Richard J. Lutton,  all  of the
GL, WES, gave constructive comments and assistance.  Mr.  Tom Roy, New  Hampshire
Water Supply and Pollution Control Commission, and Mr. Gad Tawadros, EPA
Region 2, provided assistance  and information during and  after field
visits to the two remedial-action sites described in Appendix B. Numerous
other individuals from government, industry,  and academic institutions,
only some of whom are acknowledged by name at places in the  handbook,
provided information and assistance.  The help extended by all these
people is sincerely appreciated.
                                     xxv

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                                   CHAPTER 1

                                 INTRODUCTION
1.1 Background


    Effectively covering an uncontrolled hazardous waste site may be one of
the most efficient remedial measures to limit the spread of contamination.
The cover may be a part of a total system, or it might be the only measure
used; in either case most of the geotechnical principles involved are the
same.  This handbook is an attempt to present those principles in a way that
will be useful to the cover designer.

    The term "uncontrolled" refers to existing waste-disposal sites that have
not been managed in accordance with any uniform set of standards.  Presently
operating and future disposal sites fall within the purview of the Resource
Conservation and Recovery Act of 1976 (RCRA), and are thus controlled sites.
They must be designed and operated in accordance with published regulatory
standards.   Uncontrolled sites include older sites of all descriptions.  Some
may have been operated conscientiously and according to the best technical
practice available at the time, but ranging from this optimum are all grades
of random and haphazard disposal, sometimes with little or no regard for
environmental consequences.

    The Comprehensive Environmental Response, Compensation, and Liability Act
of 1980 (CERCLA) addressed itself to the cleanup of hazardous materials sites
where contamination is being released into the environment.  Hazardous materi-
als, as defined in Section 101 of CERCLA,  comprise those substances that, when
released into the environment, threaten the public health or welfare or the
environment itself.   The fund established by CERCLA to pay for such cleanups
is commonly known as "Superfund."  CERCLA, and the regulations based on it,
govern accidental releases that may occur from time to time, but they also
govern releases that have taken place and continue to take place from uncon-
trolled waste-disposal  sites.   Cover, among other remedial  measures, may be
effective in stopping or controlling these long-term releases.

    As mandated by CERCLA, the Environmental  Protection Agency (EPA) developed
an updated National  Contingency Plan (NCR), which was published in the Federal
Register on 16 July 1982 (pages 31202-31243).   The NCP establishes certain
systematic procedures.   One of these procedures is a Hazard Ranking System,
necessary to establish priorities among the various problem sites that may be
eligible for a Superfund response.   Another procedure is for Hazardous Sub-
stance Response - Subpart F of the NCP.   The  response procedure comprises

                                      1-1

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seven distinct phases, as follows:  I - Discovery and Notification; II -
Preliminary Assessment; III - Immediate Removal; IV - Evaluation and Determi-
nation of Appropriate Response; V - Planned Removal; VI - Remedial Action;
VII - Documentation and Cost Recovery.

    Cover, as a Remedial Action, falls under Phase VI of the response proce-
dure.  "Remedial Action," defined at length in the NCP (Section 300.6), refers
to measures that are of a permanent nature and that serve to prevent or miti-
gate the migration of a release into the environment.  Section 300.70 of the
NCP provides a lengthy list of possible remedial measures, which is reproduced
in Table 1-1.

    Cover falls under "Surface Seals" in Table 1-1, under the more general
heading of "Surface Water Controls."  Table 1-1 identifies a wide variety of
available remedial methods.   The decision as to what measures to use will be
made during Phase IV of the NCP's response process, Evaluation and Determina-
tion of Appropriate Response.   Cover may never be used as the sole remedial
measure, and indeed good practice demands that all  the alternatives listed
under Surface Water Controls be taken into account, if a cover is to function
effectively.   Cover and other surface water controls will commonly be used
with other systems, (e.g., for ground-water and gas-emissions control).   Per-
haps it will  seldom be necessary to choose between cover and other systems.
Nevertheless,  relative to other remedial measures,  cover has certain desirable
attributes, which should be borne in mind.   Cover is basically a simple sys-
tem, easy to understand and relatively easy to design effectively.   It uses
simple materials and common construction techniques.   Being at the ground sur-
face, it can be observed and inspected at any time, and is accessible and easy
to repair.   It is a preventive measure, tackling the leachate problem by pre-
venting leachate formation.   In the hydrologic cycle that leads to leachate
formation and migration, cover occupies an upstream position; thus cover deals
mainly with fresh water, which is more benign and whose properties are better
known and understood than the downstream leachate solutions, as regards their
effect on materials.   While these advantages might not warrant selecting cover
in preference to another measure, they might indeed warrant emphasizing cover
as a prime component of the remedial system.


1.2 Purpose and Scope


    The purpose of this Technical Handbook is to provide guidance to the de-
signer of a cover system for an uncontrolled hazardous-waste site.   It is also
intended that the Handbook be a source of technical information for regulatory
personnel to aid them in evaluating any such design submitted for approval.

    Subjects discussed in this Handbook include:

    •    Functions that the cover system must perform.

    •    Materials suitable for constructing the system.

    •    Pertinent material test methods.

                                      1-2

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                                                                                TABLE  1-1

                                                                   POSSIBLE REMEDIAL  METHODS
 i
Co
a.  General
b.  Engineering Methods for On-Site  Actions
    1.  Control Technologies
        i.  Air Emissions Control
            A.  Pipe Vents
            B.  Trench Vents
            C.  Gas Barriers
            D.  Gas Collection Systems
            E.  Overpacking
       ii.  Surface Water Controls
            A.  Surface Seals ("covers")
            B.  Surface Water Diversion and Collection Systems
                1.  Dikes and Berms
                2.  Ditches, Diversions and Waterways
                3.  Chutes and Downpipes
                4.  Levees
                5.  Seepage Basins and Ditches
                6.  Sedimentation  Basins  and  Ponds
                7.  Terraces and Benches
            C.  Grading
            D.  Revegetation
      iii.  Ground Hater Controls
            A.  Impermeable Barriers
                1.  Slurry Walls
                2.  Grout Curtains
                3.  Sheet Pilings
            B.  Permeable Treatment  Beds
            C.  Ground Water Pumping
                1.  Water Table Adjustment
                2.  Plume Containment
            D.  Leachate Control
                1.  Subsurface Drains
                2.  Drainage Ditches
                3.  Liners
       iv.  Contaminated Water and Sewer  Lines
            A.  Grouting
            B.  Pipe Relining and  Sleeving
            C.  Sewer Relocation
    2.  Treatment Technologies
        i.  Gaseous Emissions Treatment
            A.  Vapor Phase Adsorption
            B.  Thermal Oxidation
       ii.  Direct Waste Treatment Methods
            A.  Biological Methods
                1.  Treatment via  Modified Conventional Wastewater
                    Treatment Techniques
                2.  Anaerobic, Aerated, and Facultative Lagoons
                3.  Supported Growth Biological Reactors
              B.  Chemical Methods
                  1.  Chlorination
                  2.  Precipitation, Flocculation, Sedimentation
                  3.  Neutralization
                  4.  Equalization
                  5.  Chemical Oxidation
              C.  Physical Methods
                  1.  Air Stripping
                  2.  Carbon Adsorption
                  3.  Ion Exchange
                  4.  Reverse Osmosis
                  5.  Permeable Bed Treatment
                  6.  Wet Air Oxidation
                  7.  Incineration
        iii.  Contaminated Soils and Sediments
              A.  Incineration
              B.  Wet Air Oxidation
              C.  Solidification
              D.  Encapsulation
              E.  In Situ Treatment
                  1.  Solution Mining (Soil Washing or Soil Flushing)
                  2.  Neutralization/Detoxification
                  3.  Microbiological Degradation
c.  Offsite Transport for Storage, Treatment, Destruction, or Secure
    Disposition
    1.  General
          i.  More Cost Effective
         ii.  Create New Hazardous Substances Management Capacity
        iii.  Necessary to Protect Public Health, Welfare, or the
              Environment
    2.  Contaminated Soils and Sediments Removal from Site
          i.  Excavation
         ii.  Hydraulic Dredging
        iii.  Mechanical Dredging
d.  Provision of Alternative Water Supplies
    1.  Individual Treatment Units
    2.  Water Distribution System
    3.  New Wells in a New Location or Deeper Wells
    4.  Cisterns
    5.  Bottled or Treated Water
    6.  Upgraded Treatment for Existing Distribution Systems
e.  Relocation
        Source:  NCP, sec. 300.70.  This list is  not  to  be considered inclusive of all possible methods of remedying releases.

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     •   Components and features necessary for the system to perform  its
         functions.

     •   Construction methods and equipment.

     •   Quality-control methods to insure that the system is actually  in-
         stalled as designed.

     The reader should be aware of two important things that this Handbook does
not  and cannot do.  One concerns site specifics - topography, climate,  avail-
able  materials, etc.  The designer must formulate an appropriate design for
any  given site based on these specific conditions.  The Handbook cannot offer
specific designs tailored to individual cases.

     Secondly, the Handbook does not address questions of risk assessment and
cost-benefit analysis.   These highly important matters involve public-health,
economic, political, and social questions as well as technical ones.  Often,
the  technical design must await resolution of nontechnical questions.   It is
important that both designer and regulator be aware of this fact.


1.3  Cover Functions and Attributes
    Cover may perform a number of functions, as listed in Table 1-2.  Along
with functions are listed necessary attributes, which the cover must have to
accomplish its functions.   Attributes pertain mainly to the cover's own dura-
bility and permanence.  The purpose of good design is to provide these attrib-
utes while assuring the performance of the desired function or functions.

    Of the functions addressed in Table 1-2, vectors and blowing litter and
dust are present at operating municipal waste-disposal sites, but much less
commonly so at Superfund sites.  Aesthetics and site reclamation are impor-
tant, and must be factors in the design process, but they must be considered
secondary to controlling hazardous materials or conditions.   The relative im-
portance of the remaining functions may be judged by an examination of pub-
lished descriptions of Superfund sites.  The threats at such sites are ground-
water contamination, surface-water contamination, soil contamination, bottom-
sediment contamination, air pollution, and the hazard of fire or explosion.

    Soil contamination at a Superfund site will have already occurred.  Any
present or future spread of such contamination relates to the movement of
liquids or gases.   Any action to control liquid movement will address the
soil-contamination problem as well.

    Contaminated bottom sediments represent transported contaminated soil.
Prevention of erosion of contaminated soil will prevent its further transpor-
tation.  Placing any durable cover over contaminated soil will prevent the
erosion of the soil.  However, the question of whether liquid contamination is
occurring will still have to be faced.
                                      1-4

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                 TABLE 1-2
       COVER FUNCTIONS AND ATTRIBUTES


                  Functions
Prevention or Minimization of Percolation
Promotion of Aesthetics
Suppression of Vectors
Containment of Gases
Suppression of Fire Danger
Prevention of Blowing Litter or Dust
Promotion of Site Reclamation

            Necessary Attributes

Water Erosion Resistance
Wind Erosion Resistance
Stability Against Slumping and Cracking
Stability Against Slope Failures
Resistance to Cold-Weather Distress
Resistance to Disruption by Animals or Plants
Note:  This table is adapted from Lutton,
       Regan, and Jones (1979).
                       1-5

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    Air pollution would occur if the waste substances were to give off gases
or vapors, or if the obnoxious substance were a powder and the wind were to
disperse it as a dust.   Gases and vapors may evolve from a chemical reaction
in which they are produced or merely by the evaporation of a substance with
high vapor pressure (a volatile substance).  The former of these mechanisms is
more powerful and threatening.  The reaction may be one in which two or more
reacting substances come into contact, or it may be a biochemical one involv-
ing the decay of organic material.   Reaction-produced gases will develop high
enough pressures to force their way to the surface.  Vapors from a buried body
of volatile liquid would not generate enough pressure to force their way to
the surface.   Such a vapor might, however, saturate a dry, porous soil above
it, and as days of higher and lower barometric pressure succeed one another,
the soil might "exhale" the noxious vapors in menacing quantities.  Also,
noxious vapors can reach the surface entrained with reaction-produced gases.
Where either the quantities or the nature of waste-produced gases is suffi-
ciently threatening, a system to control them must be provided.

    Fires or explosions, both of which are rapid chemical reactions, require
one or more reactable substances and an initiation mechanism.   Usually one of
the substances is atmospheric oxygen.   Virtually any cover that excludes air
and immobilizes fluids will prevent fires and explosions.

    The two remaining threats, contamination of ground and surface waters,
represent by far the greatest real  problem for which cover offers a solution.
At 85 percent of the first 160 Superfund sites publicly announced by EPA,
water contamination was reported as a problem.  Water contamination was five
times more commonly mentioned than any other problem, and at those sites where
more than one threat was recognized, water contamination was usually recog-
nized as the dominant one.   The prevention of water contamination, particu-
larly ground-water contamination, is the most difficult and challenging
assignment for a cover system.  Virtually any cover system that satisfactorily
handles the water-contamination problem also handles the other threats.

    For these reasons,  this Handbook concerns itself predominantly with covers
whose principal  function is to minimize water contamination.   Essentially,
this means preventing or minimizing infiltration and percolation.  With one
proviso, however; the problem of gas evolution is recognized,  and systems are
presented to handle it where it is  present (See Section 4.3).


1.4 Different Types of Waste Sites


    Along with different functions, there exist different types of waste
sites.   For purposes of RCRA, EPA recognizes four types of waste sites:   land-
fills,  surface impoundments, waste piles, and land treatment facilities.  In
landfills, which are probably the most common uncontrolled waste disposal
sites,  waste was dumped in excavations beneath the ground surface, commonly in
abandoned sand,  gravel, or borrow pits.  At surface impoundments, liquid
wastes are contained in some sort of holding basin:  a pit, pond, or lagoon.
Waste piles are simply sites where waste has been dumped in a mound above the
ground surface.   Land treatment is a relatively new technique whereby wastes

                                      1-6

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are spread over an area and intimately mixed into the upper zone of the soil.
Many sites will not fit neatly into one category.  For instance, a waste dump
in a ravine or on a hillside might be a borderline case between a landfill and
a waste pile.   A given overall site may have one or more surface impoundments
in close proximity to waste piles or landfills.   At some old uncontrolled
sites, liquid wastes may have been poured directly onto the ground.   It is
difficult to classify this practice into any of the above categories.

    The different types of sites may have different requirements with respect
to cover.  The cover function will not differ, but rather the cover's attrib-
utes, and certain aspects of design, will certainly vary.  A waste pile, for
instance, being above the ground surface, necessarily has side slopes, and is
potentially subject to slope failures.   This problem generally does not affect
other types of waste sites.  Slopes mean fast-running water, which means ero-
sion; thus, waste piles are degraded by water erosion, as rills and gullies
form.  A critical and difficult problem for landfill and surface impoundment
cover systems is slumping and subsidence.  This problem means that the founda-
tion on which the cover is placed must be strong.  Surface impoundments, being
liquid, present a particular problem in this regard.  If the liquids are not
removed, not only must they be stabilized by being solidified, taken up by an
absorbent, or otherwise immobilized, but the material must be strengthened so
that it will support a cover, without slumping,  over a long term.   Landfills
are low-lying, in contrast to waste piles.   Thus landfills are less exposed to
rill erosion on the slopes, but they have greater requirements for active
drainage as a matter of design.   Water tends both to collect in low spots and
to run in channels through them.  The channelized flow presents an erosion
threat, and the collection means that larger quantities of water are present
and a quantitatively larger leachate-prevention problem must be faced.

    No two uncontrolled waste sites will be precisely alike.  In all cases,
good engineering judgment, brought to bear on specific conditions at the site,
will be the most important factor in effective cover design.  Therefore, this
Handbook gives few hard and fast rules, but stresses general principles and
attempts to point out where and when a particular principle is likely to come
into play.


1.5 Concept of Cover as a Roof


    Because prevention or minimization of infiltration has been identified as
cover's primary function, it is logical to compare cover to a roof,  which per-
forms precisely the same function for a building.  Certain attributes of a
roof will relate to the attributes or properties required of cover,  and cer-
tain aspects of roof performance may instructively be kept in mind when con-
sidering cover in relation to other remedial techniques.  Six aspects common
to covers and roofs are as follows:

    (1)  Impermeable layer.  The heart of a roof is an impermeable member
which deflects rain or meltwater and prevents it from entering the building.
A cover likewise must possess a substantially impermeable member to prevent or
retard the entrance of water.

                                      1-7

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    (2)  Slope considerations.  An important attribute of a roof is its pitch
or slope.  A certain pitch is necessary to promote prompt runoff.  Too low
a pitch prevents the use of shingled construction, and a zero pitch (flat
roof) demands an especially sturdy and defect-free membrane and necessitates
positive means for disposing of the water.  Flat roofs are notorious for leak-
age problems.  All of these factors have counterparts with respect to cover.
The flatter a cover, the more demand is placed on it by a given amount of
precipitation.

    (3)  Handling of effluent drainage.  The water that a roof intercepts must
be disposed of.  It may be allowed to flow or drip off the edge, it may be
collected in a gutter or downspout, or in a suitable climate (warm, sunny,
windy) it may simply be allowed to evaporate.  Effective operation of the roof
demands that this disposition mechanism work properly.  Just so with covers:
good drainage will minimize the demand placed on cover, and maximize its
effectiveness and its life.

    (4)  Mechanical stability.  A roof must be properly supported, and sturdy
enough not to warp or bend.  Its components must be strongly enough assembled
not to be torn apart by wind, frost, or other agents of weathering.  Analo-
gously, a cover system must be so designed and built that mechanical strains
do not lead to its failure.  Desiccation of materials within a cover system
might lead to such mechanical strains.

    (5)  Chemical stability.  If a roof is in a special service, as where
exposed to a corrosive atmosphere above or below, it may fail unless special
protective measures are employed.  Similarly a cover system at a hazardous
waste site, because of the substances with which it is in contact, may require
special attention to insure its chemical stability.

    (6)  Long-term stability.  Some slate or tile building roofs may endure
for centuries.  Other roofs of cheap synthetic materials may have to be re-
placed within a few years.  Not only the materials, but the construction
standards and design, affect a roof's longevity.  It is surely likewise with
cover systems:  materials, construction, and design will all affect their
long-term performance.

    The analogy with roofs may be carried one step further by mention of
structures in which roofs serve their purpose without the assistance of walls
and floors.  Such structures are "bohios" (Spanish; thatched-roof huts without
walls) in tropical rural societies, equipment sheds on farms, and even car-
ports.  These structures do not furnish complete protection from the elements,
and if rain occurs accompanied by wind, their protected contents do indeed get
wet.  Nevertheless, these structures perform their intended function of de-
flecting the great majority of precipitation.  The analogy with cover would
relate to a cover system not accompanied by either a bottom seal beneath the
waste deposit nor an impermeable side wall around it.  If the great majority
of precipitation could be deflected from passing through the deposit, the
result might be a sufficient beneficial effect (through removing the driving
force behind waste migration), to control the problem at hand, even without
these other protective devices.


                                      1-8

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 1.6  Ideal Versus Real Covers
    The ideal cover system would be simple, effective, reliable, durable,
stable in contact with all kinds of waste, aesthetically attractive, and inex-
pensive, and would require no maintenance nor attention after it was placed.
In reality, certain requirements conflict with others.  Virtually all realis-
tic materials are stable in the presence of some waste substances, but not of
others.  Vegetation can both be aesthetically attractive and perform valuable
functions to aid both the cover's integrity and its effectiveness; however,
left unmanaged, vegetation will inevitably tend to disrupt and ultimately
destroy the cover.  Virtually nothing is totally weathering and erosion resis-
tant; the more such resistance is desired, the more will have to be paid for
it.

    Thus, in real covers, certain inevitable trade-offs have to be faced.  In
this Handbook, we attempt to make these trade-offs clear and to present the
factors that enter into them so that the designer may weigh them judiciously
against one another.


1.7 The Hydrologic Cycle as Applied to Covers


    An understanding of the hydrologic cycle is basic to an understanding of
the functioning of a cover system.   The hydrologic cycle refers to the contin-
uous process in nature whereby water is continually in movement and transi-
tion.  Summaries of this complex process can be found in numerous texts, e.g.,
Davis and DeWiest (1966) or Gilluly, Waters, and Woodford (1959).   Those pro-
cesses that take place in and about a landfill site are those that require
closer attention.

    Elements of the hydrologic cycle important at a landfill site are shown in
a simplified way in Figure 1-1.   Most of these elements will be familiar to
the engineer.   Brief discussions of them follow.

    Rainfall and snowfall, the two common forms of precipitation,  need little
explanation.  Both are measured and reported in linear units, commonly inches
in the United States.   Technically the linear measurement can be thought of as
the quotient of a volume of material being deposited on an area of ground.
For hydrologic analysis, snowfall  should be reduced to equivalent rainfall,
that is,  amount of water resulting from melting of a given quantity of snow.

    Runoff in the context of a landfill  is equivalent to surface runoff in a
hydrogeological discussion (e.g.,  Davis and DeWiest, 1966, p.  23).   It refers
to that portion of the water that,  having fallen on the ground,  leaves the
system without penetrating beneath the ground surface.

    Evaporation is the process by which liquid water evaporates  into gaseous
water vapor, and thus passes into the atmosphere.   Transpiration is the pro-
cess by which plants  lose water to the atmosphere.   It is common to refer to
evaporation and transpiration jointly as "evapotranspiration" since it is

                                      1-9

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                                  FIGURE 1-1

                         ELEMENTS OF HYDROLOGIC CYCLE


/*
SNOWFALL

ASUBLIMATION
	 >_.„ ._. '-„ . ,-. A

RAINFALL K A
ccr\
/xO TRANSPIRATION
.EVAPORATION 1
RUNOFF *
' . , ^... 1 j^"r 	 >-r—)a
'!, 1 -* .
                        llNFILTRATION
  GROUND
  SURFACE
                      PERCOLATION
ARBITRARY
HORIZON
                                                                     WATER TABLE
                  LATERAL FLOW
                                               ZONE OF SATURATION
difficult to measure the two effects separately.  Nevertheless it is probably
well to remember that they are two distinct processes.

    Sublimation is the direct passage of water from its solid state in snow to
its gaseous state in water vapor without passing through a liquid stage.  Prob-
ably a considerable amount of moisture that falls as snow returns to the
atmosphere via this pathway.

    Infiltration is the passage of water downward through the ground surface
and into the soil.

    Percolation is the downward migration of infiltrated water.  As indicated
in Figure 1-1, its quantity at any given horizon would be the net downward
flow passing that horizon.

    The water table is a level below which the ground is saturated.  The zone
of saturation may continue downward indefinitely, in which case the water
table is a general water table; or the saturated zone may bottom at an imper-
vious boundary of finite extent, there being further unsaturated material
beneath this impervious boundary.  In such cases the water is said to be
perched, and the water table is a perched water table.

    The water in the zone of saturation is what is commonly termed ground
water, and in general it is in motion laterally as indicated in Figure 1-1.
                                      1-10

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    An  important  factor not  shown  in Figure 1-1  is water storage in the soil.
Depending upon  its mechanical composition, a given soil can hold any given
amount  of water,  up to a maximum.  At this maximum water content, the soil is
saturated.  At  some lesser water content, known  as the field capacity, the
soil holds all  of its water  in place, without allowing it to drain by gravity.
Only in soils with more water than the field capacity does gravity drainage
freely  take place.  The soil thus can and does act as a reservoir, which  is
full when the soil moisture  is at field capacity.  The filling and emptying of
this reservoir  over time plays a vital role in the local hydrologic cycle, and
in the  performance of a cover system.  A clear,  easy-to-understand discussion
of this process is given in  Fenn, Hanley, and De Geare (1975).  (Some slight
drainage may in fact occur with water contents short of field capacity, but
the outline given here is basically correct.)

    Those components of the  hydrologic cycle that affect the functioning  of a
cover system are discussed in detail in section 4.2 of this Handbook, "Infil-
tration and Percolation."

    For a proper response at any Superfund site, it is extremely important
that the ground-water regime be well understood.  A large proportion of the
site exploration budget may  properly go for this purpose.   Such exploration
will probably have been done as part of the early Superfund response.   The
cover designer  should assure himself that the ground-water regime is well
established, since such knowledge is essential to the proper design of cover
as well as other remedial measures.

    On a long-term basis'the hydrologic system may be in equilibrium,  i.e.,
operating at a  steady state.   However, on a short-term basis many, perhaps
most, elements of the system are in other than a steady state, their posi-
tions,   rates, or measurable attributes fluctuating around a steady-state
average.  Some  fluctuations are large and rapid, others may be very slight
and slow.

    The more variable processes and properties tend to be those higher in  the
cross section - nearer to the ground surface.   Those at depths vary more
slowly and probably over smaller ranges.   This points up a marked difference
between the cover and the 1iner at a waste-disposal site,  both of which serve
to intercept and control  the flow of fluids.   The hydrologic processes operat-
ing in a cover system are likely only rarely to be in a steady state.   Most of
the time they will be varying from one state to another.   In a liner,  on the
other hand,  conditions once established will  tend to persist,  and a fairly
close approach to steady state will exist.   This has important applications
for example in considering the flow of intergranular fluids.   Such flow under
saturated conditions and at a steady state is  described by Darcy's Law,  with
which most engineers are familiar and which is discussed later in this Hand-
book.   Darcy's Law as applied to liners is probably quite valid.   For covers,
however, it is probably only an approximation, describing what would take
place under certain limiting conditions,  which might occasionally occur but
which probably usually do not.
                                      1-11

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                                    CHAPTER  2

                              SITE CHARACTERIZATION
    This chapter discusses  those characteristics of a site that affect a cover
 system's construction or  influence  its performance, and therefore »ust be con-
 sidered in the process of cover design.  A design may be seriously deficient
 if  it fails to take into account the pertinent features and peculiarities of
 the site.

    The designer of cover,  or of other remedial measures, should have at his
 disposal the results of a site investigation performed earlier in the Hazard-
 ous Substance Response process (see Section 1-1).  The purpose of this chapter
 is to serve as a check against the Site Investigation report, to determine if
 all pertinent characteristics were covered.
2.1 Data Requirements


    The site package should include the following types of data:

    •    Topography

    •    Soils

    •    Geo1ogy

    •    Hydrology and hydrogeology

    •    Aerial photographs

    •    Cultural features

    •    Vegetation

    •    Climate

    •    Waste characteristics

    If the site investigation report does not have adequate data to design a
cover system, then the designer must rely on two types of data collection ac-
tivities:   (a) consult background or readily available data,  and/or (b) per-
form an onsite investigation.   The following paragraphs are devoted mainly

                                      2-1

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to collecting available data,  with only a short discussion of onsite investi-
gation.   This is not intended  to imply that the latter is unimportant;  indeed,
specific site information is essential to proper cover design.   However,  a
detailed presentation of investigation methods would require an extensive
treatment.   It was decided not to undertake such a treatment here.   Refer-
ences are given, however, to several  works that provide guidance for site
investigation.


2.2 Data Sources


    Sisk (1981) presents an excellent summary of the relevance and availabil-
ity of background information for hazardous waste site investigations and is
recommended for consultation by the cover designer.   Another reference manual
which is readily available and highly recommended is the U. S.  Bureau of
Reclamation "Earth Manual" (U. S. Bureau of Reclamation, 1974), which gives
abundant information of direct interest to the cover designer for obtaining
background information and also as regards all phases of soils.

    Data collection activities are discussed in the following paragraphs for
each type of  data required.


    2.2.1 Topography


    The topographic map  is probably the most useful single document relative
to a cover project.  The map  reveals the lay of the land at the project site
and in  its vicinity; shows the surface drainage network, a matter of fundamen-
tal importance; gives  information as to presence and location of cultural
(man-made) features; and makes it possible to define place locations specifi-
cally by any  desired system:  latitude and longitude, public-land system
(township, range, section, and subsection), or  state coordinate system.

    The U. S. Geological Survey  (USGS) is the source of most published topo-
graphic maps.   The  scales  of  published topographic maps are  1:24,000 (1 in.
equals  2,000  ft)  or  1:31,680  (1  in. equals 1/2  mile) for 7-1/2-minute quadran-
gles, 1:62,500  (1 in.  equals  approximately 1 mile) for  15-minute quadrangles,
and  1:250,000 (1  in. equals about 4 miles).*   It will always be necessary  to
have a  site  topographic  map at a larger  scale than that of the published  maps.
Nevertheless  the  published quadrangle map should be obtained as a basic refer-
ence.   An  index of  each  state showing the available coverage and topographic
quadrangle maps may be obtained  direct from the USGS at addresses shown  in
Appendix J.   In many cases selected maps  are  also available  locally in vari-
ous  cities from commercial  dealers.   Informative discussions of topographic
quadrangle maps are given  in  the Earth Manual  (U. S. Bureau  of Reclamation,
1974b), Thompson  (1979),  and  Krynine  and  Judd  (1957).


*  Numerical  data in this  Handbook  are presented  in  units  corresponding  to cur-
   rent  American usage.   A  metric conversion  table may  be  found in Appendix D.

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     2.2.2  Soils
    The U.  S. Department  of Agriculture  has published  an  extensive  series of
 soil  survey maps.  These  maps  are  discussed and described in U. S.  Bureau of
 Reclamation (1974b) and Krynine and Judd (1957), and a complete listing  to
 date  of published  soil surveys is  presented in an appendix to  Sisk  (1981).
 Commonly  these  surveys are performed on  a county basis, but many are on  an
 area  basis  and  include portions of one or more than one counties.   These sur-
 veys  are  performed for agricultural purposes and they  are biased toward  agri-
 cultural  requirements.  Mapped soil units are called soil series and are named
 for a county, city, river valley,  etc.,  where they are typically developed.  A
 soil  series, however, reflects only the  soils in the agricultural soil pro-
 file, which is  usually less than 6 ft deep.  Reports since 1975 contain  engi-
 neering uses of soils mapped, parent materials, geologic  origin, climate,
 physiographic setting, and soil profiles.  The soil maps  are presented on
 photomosaic background for each county at a scale of 1:15,840  or 1:20,000.
 Recent reports  include engineering test  data for soils mapped, depth to water
 and bedrock, grain-size distributions, engineering interpretations, and  spe-
 cial  features.

    Not many soils maps have the soils classified in engineering terms.  How-
 ever, an  instructive discussion of the geography of soils considered from an
 engineering point of view, with maps covering North America, may be found in
 Woods, Miles, and Lovell  (1962).    Informative discussions of the formation and
 distribution of soils may also be  found  in Peck, Hanson,  and Thornburn (1974)
 and Mitchell (1976).

    For many sites, information from nearby soil borings  may be found in the
 files of  the pertinent state highway department.


    2.2.3 Geology


    A variety of geological  reports and maps are available for the cover de-
 signer.   The scales of geologic maps include 1:24,000,  1:62,500, 1:100,000,
 1:250,000,  and smaller.   There are two major types of geologic maps.  One is
 the formation or "bedrock" geologic map,  which,  for a given area,  indicates
 the material underlying the overburden soils.   This is  the most common type of
 geologic map;  state geologic maps  fall  in this category.   The other type is
 the surficial  geologic map,  which  specifically indicates  the material  lying at
 the ground  surface.  Glacial-geology maps are probably  the most common geo-
 logic maps  in this category.   Both types  may be useful  in locating sources of
 natural  cover material.   The principal  sources of geologic maps and reports
 are the USGS and the State Geological  Surveys or Departments of Natural Re-
 sources.   See Appendix J for addresses.

    A new series of indexes  of geologic maps for each state was started in
 1976,  and lists of geological  maps and reports for each state are published
periodically by the USGS.   Each state  geological  survey has a list of maps and
 reports  published covering its state.

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    Discussions of geologic maps and their use for engineering purposes are
presented in Krynine and Judd (1957) and in U.  S.  Bureau of Reclamation
(1974b).
    2.2.4 Hydrology and Geohydrology


    Maps showing hydrologic and hydrogeological  information provide a valuable
source of data in surface drainage, well locations, ground-water quality,
ground-water levels, seepage patterns and aquifer locations and characteris-
tics.  A good source is the USGS which has prepared Hydrologic Investigations
Atlases with a principal map scale of 1:24,000.   The atlases include water
availability, flood areas, surface drainage, precipitation and climate, geo-
logy, availability of ground and surface water,  water quality and use, and
streamflow characteristics.  Some maps show ground-water contours and location
of wells.

    Some of the state field offices of the Water Resources Division of the
USGS have water well logs which may be useful.


    2.2.5 Aerial Photographs


    High-quality, large-scale (1:20,000) stereoscopic aerial photographs are
particularly useful for interpretating drainage patterns, topography, land-
forms, vegetation, land use, and cultural features.  The most readily avail-
able aerial photographs are panchromatic (black and white).  Other types that
are available include color and color infrared,  which are extremely useful but
coverage is less extensive and more expensive than black-and-white air photos.
The principal sources of aerial photographs are the Department of Agricul-
ture's Agricultural Stabilization and Conservation Service (ASCS) Aerial
Photography Field Office, 2511 Parley's Way, Salt Lake City, Utah  84109,  and
the USGS.  The USGS has four mapping centers where aerial photographs may be
obtained, located in Denver, CO, Rolla, MO, Menlo Park, CA, and Reston, VA.
For complete addresses see Appendix J.  Good discussions of the use of air
photos and how to obtain them are given in U. S. Bureau of Reclamation
(1974b), Sisk (1981), Krynine and Judd (1957),  and Office, Chief of Engineers,
Engineering Pamphlet 70-1-1.


    2.2.6 Cultural Features


    Cultural features that should be the concern of the cover designer include
transportation, network utilities (pipelines, telephone and power lines),
location of urban centers, and availability of manufactured construction mate-
rials.  Some of the data listed above can be extracted from the maps pre-
viously discussed, and other data can be obtained from the local Chamber of
Commerce, the city or county engineer, utility companies, and local construc-
tion contractors.

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    2.2.7 Vegetation Data
    Information on existing vegetation in the site vicinity is important from
a cover standpoint.   Vegetative protection of the cover is an important fac-
tor.  Volunteer plant species in the area are an indicator of highly stable
species and of species likely to invade the cover spontaneously.   Cultivated
plants in the area are also obviously stable locally, although requiring cer-
tain specific management practices.   Sources of background information
include:

    •    USDA - Agricultural County Agents
              - ARS - Agricultural Research Centers

    •    SCS - Local Offices
             - Technical Service Centers
             - Plant Materials Centers
             - Plant Materials Specialists

    •    U.  S. Forest Service - Local or State Offices
                              - Forest and Range Experiment Stations

    •    L).  S. Army Corps of Engineers - District Offices, Environmental
                                         Resources Section
                                       - USAE Waterways Experiment Station,
                                         Environmental Laboratory

    •    County or Municipality - Land Use Planners
                                - Land Use Plans

    •    State Universities - Local  faculty - Plant Identification
    2.2.8  Climatic Data
    The climatic or meteorological data for a given site is an important fac-
tor as regards cover.   The cover, more than any other component of the reme-
dial system, is directly exposed to the weather.   Climate directly affects
vegetation; the climatic factor of precipitation forms the input to the
infiltration-percolation process that the cover system is intended to control;
other climatic factors and their distribution -influence the process strongly.
Specific climatic data are required as input to the hydrologic modeling meth-
ods discussed later in the Handbook as means to predict a cover system's ef-
fectiveness.  Weather conditions directly affect construction operations and
may be important in planning the construction phase of cover installation.

    Climatic data must be obtained from background sources, since a historical
picture, rather than merely a short-term sampling, is important.   The primary
source of climatic data in the United States is the National Climatic Center
(NCC), operated by the National Oceanic and Atmospheric Administration of the
U. S. Department of Commerce.  The NCC's address is:   National Climatic Center,

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Federal  Building, Asheville,  NC   28801  (Telephone number:   (704)  258-2850).
A  list of publications  and publication  series may be obtained from NCC by
written or telephonic  request.   Some of these publications are  listed in
Table  2-1.

                                       TABLE 2-1

               SELECTED  PUBLICATIONS OF THE NATIONAL CLIMATIC CENTER
          Title
Publication
 Frequency
Contents
Local Climatological Data (LCD)


Climatological Data (CD)


Storm Data

Monthly Climatic Data for the
World (MCDW)

Hourly Precipitation Data (HPD)
Climatic Atlas of the United
States
Selected Climatic Maps of the
United States

Climates of the States
 Monthly;     Meteorological data for 285 National  Weather Service
 annually     stations

 Monthly;     Meteorological data for states and combinations of states
 annually

 Monthly      Information on severe storms

 Monthly      Meteorological data for selected stations throughout
            world

 Monthly;     Hourly and daily precipitation data for states or combi-
 annually     nations of states (except Alaska)

            80-page large-format collection of 231 maps, 21 graphs,
            and 13 tabulations depicting various aspects of climate
            of the U. S.

            Abbreviated version of Climatic Atlas consisting of 32
            maps

            Published for each state; summary of state climate, tabu-
            lated data excerpted from pertinent annual state LCD's,
            Climatological summary for selected locations in state.
            (Climatography of the U. S., No. 60)
     2.2.9 Waste Characteristics
     From the  point of  view of  the remedial  action  as a whole, it  is important
to  know as specifically as possible the  type and  form, the  quantity,  and  the
location of buried wastes.  Material representing  a collapsible foundation,
such  as buried  drums of liquid,  presents a  threat  to cover  stability.   Wastes
that  evolve gases are  of concern to the  cover designer;  he  should know if pos-
sible what will  be evolved and in what quantities.   In general, the cover is
probably free from attack by aggressive  liquids in the waste; in  this respect
the  cover designer's problem is  very much simpler  than that of the designer  of
a liner or a  slurry wall.   In  some topographic situations,  a sloping cover
might be attacked by laterally migrating liquids.   In such  cases  the designer
should be informed as  to the compatibility  of his  cover  materials with the
wastes.

     Source of available data on  the waste site include the  city or county
sanitation department  or the operator/owner of the site.  The state EPA or its
equivalent may  have data on the  site.  A high probability exists  that available
                                          2-6

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data  pertaining to  a Superfund  site have  been collected  because these data
were  necessary to place a site  on the list  of Superfund  sites.
2.3 Specific Site  Investigations
     If  sufficient  information  is  not available from background sources or from
previous  site investigations the  designer will need to  collect additional spe-
cific site data.   These may include preparation of site topographic  maps,
programs  aimed at  detecting and  locating buried objects,  including waste con-
tainers,  or explorations of the  site soil profile and of available soil  borrow
areas in  the vicinity.   It is  not within the  scope of this  Handbook  to de-
scribe  the investigation techniques required.   Guidance is  available from
various  sources, many of which are listed in  Table 2-2.

     Useful  guidance  for soil exploration may  be found in the highway plan of
the  state highway  department.  This plan is oriented toward the geology  of the
particular state and the specific exploration methods found necessary there.

                                      TABLE 2-2

                    SOURCES OF GUIDANCE FOR SITE INVESTIGATIONS
                                Soils Exploration

        American Society for Testing and Materials (annual, Part 19; specifically,  D-420)
        Clayton, Simons, and Matthews (1982)
        Department of the Army (1984)
        Hough (1969)
        Hvorslev (1948)
        Krynine and Judd (1957)
        Parcher and Means (1968)
        Peck, Hanson, and Thornburn (1974)
        Sowers and Sowers (1970)
        Taylor (1948)
        Teng (1962)
        Terzaghi and Peck (1967)
        Tomlinson (1969)
        U. S. Bureau of Reclamation (1974a; 1974b)

                                Geophysical Methods

        Clayton, Simons, and Matthews (1982)
        Department of the Army (1979, 1984)
        Dobrin (1976)

        Evans (1982)
        Tel ford et al. (1976)
                                         2-7

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                                   CHAPTER 3

                        MATERIALS USED IN COVER SYSTEMS
3.1 Introduction
    The overriding purpose of a cover system is to hinder water from entering
the wastes from the top.  The attributes of the cover must include stability
against erosion, slumping and cracking, slope failures, disruption by animals
and plants, and disruption by the effects of cold or hot, dry weather.  The
ideal cover would perform as a tight roof and possess all these attributes.
In reality, these goals may work against one another, and any or all of them
may work against the goal of minimum cost.  The task of the designer is to
achieve the best balance among competing goals at an acceptable cost.

    This chapter deals with materials that the cover designer has at his dis-
posal.  The following chapter deals with the process of design itself - how
the materials are combined and put to use.  A designer may be guided by his
own experience or knowledge of successful measures used elsewhere.  The one
indispensable requirement for any material is that it must do the job at hand.

    In this Handbook, materials have been divided into two basic categories,
soils and nonsoils, following the practice of Lutton, Regan, and Jones (1979).
Soils may be defined for present purposes as any naturally occurring particu-
late material.  Discussed under soils are various mineral-based additives by
which soil properties may be amended.  Their use results in what are known as
stabilized or modified soils.  Nonsoils include a variety of materials and
supplies, some synthetic and some natural.  Living matter such as vegetation
is not considered under "materials."

    The discussion of soils and their properties which follows is somewhat
broader than necessary for a design manual.   This approach has been adopted in
an effort to provide technical background for the benefit of regulatory per-
sonnel without geotechnical training.


3.2 Soils as Cover Materials
    Soils will form the great majority of the materials used in any cover sys-
tem.   This section deals with the attributes of soils that lead to their clas-
sification and their functioning in cover applications.


                                      3-1

-------
    3.2.1 General Soil  Factors
    Simple definitions of soil  are relatively easy,  but an all-comprehensive
one is difficult.   A definition of soil  in the literature of any specialty
tends to stress the attributes  of interest to that specialty and to slight
those of interest to others.   Certainly  the most basic attribute of soil  is
that it is a particulate material.   In general soil  is a natural material, and
any particulate material produced by human activities is to be regarded sepa-
rately.  The agronomist is concerned with soil as a  medium to sustain plant
life, and stresses the organic  content of soil as an essential part of its
definition.   This characteristic may be  of little or no interest to the engi-
neer or geologist.  The engineer is concerned with the mechanical properties
of a soil and its behavior as an engineering material.  Very often these are
directly related to the presence and action of water.   Both water and organic
matter are mobile, variable components of a soil.

    The cover designer is predominantly  concerned with soils from the view-
point of the engineer.  However, he shares the concern of the agronomist, be-
cause he is interested in producing a cover with stable vegetation.   Most of
the discussion of soils in this Handbook will be engineering-oriented, but
factors important to vegetation will be  outlined also.

    One characteristic of any particulate aggregation is its gradation.  Me-
chanical analysis, mechanical composition, and particle-size distribution are
all synonymous terms for gradation.  This basic characteristic is a component
in all the soil-classification  systems discussed below.

    Because soil is a natural material,  its grains or particles are composed
of mineral (or organic) substances.  The most common mineral in the coarse
grains is quartz (crystalline silicon dioxide, SiCL).   This mineral is a hard,
stable mineral lacking in cleavage, and  thus forming equant grains without
flat or long shapes.  By contrast, a variety of minerals form the fine grains.
These include quartz, oxide minerals such as aluminum and iron oxides, and
organic matter; but the dominant and most important component is the large and
complex group known as the "clay minerals."  These are silicate minerals with
a distinctly planar structure (phyllosi1icates), in contrast to quartz.  Be-
cause of their small size and platy shape, the specific surface of fine-
grained soils, and particularly those rich in clay minerals, is enormously
greater than that of coarser-grained soils.

    Any particulate aggregation is characterized by the factors of structure
and texture.  These related terms refer to the arrangement or disposition of
individual grains relative to one another.  For the relatively simple shapes
of grains in the coarse fraction this refers to looseness or denseness of
packing.  For the more complexly shaped grains of the fine fraction, this in-
cludes both packing and such effects as flocculent structure (Figure 3-1).

    The particulate skeleton of a soil may be regarded as its "permanent"
part.  The void space between the particles is filled with air, water, or
both.  These fluid components play an exceedingly important part in deter-
mining soil properties and behavior, especially in the fine-grained soils.

                                      3-2

-------
                                   FIGURE  3-1

               FLOCCULENT STRUCTURE  OF  SENSITIVE CLAY SUGGESTED
                            BY A.  CASAGRANDE (1932)
                   Flocculated Colloidal Particles
                   ol High Degree of Consob
                   Due to Local Coriceotra
                      of Pre«ure
Both the quantity of water and  its  disposition with regard to soil particles
and mineral molecules play important  behavioral  roles,  from both	-"—""'—
and agricultural standpoints.
engineering
    Discussions of the complex  clay-water-electrolyte system that exists in a
fine-grained soil may be  found  in  various  articles and texts, e.g., Mitchell
(1976).  Clay-mineral molecules*,  because  of widespread substitution among the
ions forming their crystal  structure  (Si"1"1"1"1",  Al+++,  Ca++, Mg"1"1", and others),
routinely have net residual  electrical  charges.   They thus attract to their
surfaces ions in solution as well  as  the appropriate  ends of water molecules.
(The water molecule  is "polar,"  i.e.,  electrically asymmetrical.)  The phenom-
enon is known as adsorption  (see definition in glossary).   The adsorptive
forces are of varying strengths, and  a wide variety of surface-related elec-
trochemical phenomena are possible and indeed take place.

    Besides minerals and  fluids, some  soils have one  or more organic compo-
nents.  Most agricultural soils  are basically mineral soils in which organic
matter has become incorporated  through plant and animal growth.   There are
also soils whose basic components  are  organic matter, such as peats.
   "Molecule" is used here  in  a  general  sense;  it is recognized that ionic sub-
  stances, such as most minerals,  may  not  contain discrete molecules as such.

                                       3-3

-------
    To geographers and geologists, the origin of a soil is of importance.  The
two major subdivisions by origin are residual and transported soils.  The
residual soils are simply the altered part of rock which has decomposed.  The
transported soils represent particulate material that was once a residual soil
but has been eroded, transported, and deposited as a sediment.  Various sedi-
mentary processes lead to different types of soil deposits.  Such terms as
"glacial" or "alluvial" soils refer to mode of origin.  Origin is not a de-
scriptive matter, but requires inference from a study of various factors.
Knowledge of a soil's origin is not essential when using it in an engineering
application, but such knowledge can often be very helpful in interpreting,
understanding, and even predicting observable descriptive factors.


    3.2.2 Common Soil Terms
    Certain basic soil descriptive terms need to be understood.  Gravel com-
prises granular material of coarse to very coarse grain size.  The grains in
sand range from coarse down to fine but still visible with the naked eye.
Silt is the coarser and less plastic portion of the material finer than sand.
Clay is the finer and more plastic portion of the material finer than sand.
The term "fines" applies collectively to silt and clay.  Loam is a term used
only in agricultural classifications and designates a mixture comprising sand,
silt, and clay, or at least two of these three components.  The numerical
limits of these size fractions are discussed below under "classification."

    The term "clay" is sometimes misunderstood because it is used in three
related yet distinct senses.  "Clay sizes" refers to particles less than
2 microns in dimension (0.002 mm) (or other limiting size, depending on system
in use).  "Clay" used alone refers to a natural material that behaves plasti-
cally when wet, within a certain range of moisture content.   The "clay miner-
als" refer to a distinct group of mineral species, all of which are hydrous
aluminosilicates with a platy crystal structure.  The most common clay mine-
rals are kaolinite, montnorillonite, illite or hydrous mica, and chlorite.
Confusion arises because a soil may be composed of clay-sized particles of
minerals other than the clay minerals (e.g., quartz, other forms of silica,
oxides of iron or aluminum).  Such a soil is likely not to show "clay-like"
(plastic) behavior.

    Classification systems (see below) commonly group soils first into coarse-
grained and fine-grained soils.  Terms commonly associated with coarse soils
are "granular" and "cohesionless."  Terms commonly associated with fine soils
are "cohesive" and "plastic."  Within the fine-grained soils, however, there
are great variations in cohesiveness and plasticity.

    "Grading" refers to a soil's gradation or mechanical composition.  Well-
graded soils possess significant quantities of all grain sizes from coarse to
fine.  Poorly graded soils may be uniform, possessing only a small range of
grain sizes, or "gap graded," possessing coarse and fine grains but few or
none of intermediate sizes.
                                      3-4

-------
    The terms "intact" and "remolded" refer to whether  a  soil  is  in  its  natu-
ral, undisturbed state or has been moved, handled, processed,  or  otherwise
disturbed by human activity.  The behavior of some soils  differs  drastically
between the intact and the remolded states.  Such considerations  are  important
when soils serve as foundations, but are  less so when the soils serve as
materials, since in materials applications soils are always  remolded  to  some
degree.
    3.2.3 Soil Properties
    The following discussion follows Taylor (1948).  A  soil mass  is  commonly
considered to consist of a network or skeleton of  solid particles, enclosing
voids or interspaces of varying size.  The voids may be filled with  air, with
water, or partly with air and partly with water.
    The total volume of
of two essential parts, the
The volume of voids in turn
             a given soil sample is designated by  V
                 volume of solids  V   and the volume
                 is subdivided into water volume  V.
                                                                 and consists
                                                                 of voids  V
                                                                 and gas
                                                       This figure is a
diagrammatic representation because all void and solid volumes cannot be
regated as shown.   However, for studying interrelationships of the terms
in this section such sketches help greatly.
ume
      g
These volumes are indicated in Figure 3-2.
vol-v
                                                                         seg-
                                                                         given
    Volume ratios which are used in soil mechanics are porosity, void ratio,
and degree of saturation.
                                  FIGURE 3-2

             DIAGRAMMATIC REPRESENTATION OF SOIL AS A THREE-PHASE
                SYSTEM, SHOWING WEIGHT AND VOLUME NOTATIONS AND
                                 RELATIONSHIPS
WEIGHT VOLUME
t
0
T-
*


w,
1

AIM
^
WATEM

W///,
/SOLID/
/^^


TV
Vw
j



V
V


v, ,
1 1
                                        WEIGHT
                                                   VOLUME
                                         W
                                           W,
                                              WATER
                                                    Vw Vv
                                                      V,
                        MOIST SOIL
                                           SATURATED SOU.
                                      3-5

-------
    The porosity  n  of the soil  mass is defined as the ratio of volume of the
voids to the total  volume of the  mass.

    The void ratio   e  of the mass is defined as the ratio of volume of voids
to volume of solid.

    The degree of saturation  S  is defined as the ratio of volume of water to
volume of voids.

    These ratios may be written

                                        V
                                    n=^                               (3.1)


                                        V
                                    e=^                               (3.2)


                                        V
                                    S = ^                               (3.3)
                                         v

    The void ratio  is usually expressed as a ratio, whereas porosity and
degree of saturation are commonly expressed as percentages.  A variety of
working relationships among these basic soil properties may be derived by
simple algebraic manipulation.  See, for example, Department of the Navy
(1982).

    Porosity as defined above is  used in many branches of engineering and is
more familiar than the void ratio to engineers in general.  However, in soil
mechanics it is more convenient in the majority of cases to use the void
ratio, principally because, when  a given specimen of soil is compressed, the
denominator of the void ratio expression remains constant, whereas both numer-
ator and denominator of the porosity expression vary.

    The total weight of a soil sample is designated by  W  , the weight of
solids by  W  , and the weight of water by  V/w .  A ratio of weights is
the water content  (or moisture content).

    The water content  w  of a soil sample  is defined in soil mechanics as the
ratio  of weight of water to weight of solids.  It is commonly expressed as a
percentage and may be written
                                        W
                                    w =
w                               (3.4)
                                        W
    The water content defined in equation 3.4 is a ratio, or percentage, of
the weight of water to the weight of solids.  This practice is not standard
in all branches of science, the water content being defined in geology, for
example, as a percentage of total weight.  Therefore this definition as given
                                      3-6

-------
 should be carefully  noted.   Note also that the upper  limit of water content is
 indefinite.  Some  soils have water contents of several hundred percent.

    The  idealized  concept  used  herein assumes that solid grains and water are
 two definite and separate  phases of a soil.  However, the actual situation is
 much more complex, because water may exist in a number of forms and mineral
 grains contain combined water.  When a sample is heated to evaporate the pore
 water, certain amounts of  combined water may also be  driven off, the amount of
 loss of  combined water depending mainly on the temperature used.  To give a
 fixed definition of  what is  to  be considered as water, it is commonly stated
 that all weight lost in evaporation by heating to 105° or 110°C is water; all
 remaining, solids.   In other ways the simple two-phase concept is not strictly
 true.  Dissolved salts in  the water may change the unit weight appreciably;
 for example, sea water has a unit weight of about 1.025 grams per cc.   If the
 sample is heated to  drive  off the water, the salts remain and become part of
 the solid weight.   Therefore the diagram of Figure 3-2 must be recognized as
 one based on simplified concepts.

    Variations in  the water  content of a given soil change its characteristics
 to such  a marked degree that the importance of this soil property cannot be
 overemphasized.

    The  unit weight  or weight per unit of volume is designated by  y .   The
 following expressions hold for  the mass unit weight or unit weight of the soil
 mass as  a whole,   y  , the unit weight of solids,  y  , and the unit weight of
 water  y
       '
        w
                                         V                               (3.5)
                                    Ys=^                              (3.6)
                                          s
                                         W
                                         f                              (3.7)
                                          w
    The dry unit weight of a soil, frequently referred to as dry density, is


                                         W
                                    Yd = >r                              <3'8)


    The dry density of a soil is directly related to its void ratio.   A given
soil may contain varying amounts of water from none up to complete saturation,
but so long as its void ratio remains constant, so does its dry density.

                                      3-7

-------
    The specific gravity of soil  solids,  defined identically with other mate-
rials as a ratio of densities with respect to pure water,  is relatively unim-
portant as regards a soil's behavior.   When testing soils,  it usually must be
determined, however, as its value is required to compute properties such as
void ratio and degree of saturation.   Specific gravity is  denoted  G   or
simply  G .

    Density of soils is frequently spoken of but in an inexact way.   Contrasts
are drawn between "dense" or "very dense" soils and "loose" or "very loose"
soils, the void ratios of the former being relatively small and of the latter
being relatively large.  A quantitative measure of density used for cohesion-
less soils is relative density, denoted  D. , and defined by



                               D    Jmax	1_                          (3 9)
                                d   e    - e .
                                     max    mm
where the various  e's  refer to the actual void ratio and the highest and
lowest possible values that soil could attain under certain specified compac-
tion procedures.  Relative density is used only in connection with granular
(cohesionless) soils.  Correlations exist between relative density and the
commonly used Standard Penetration Test for field studies (ASTM D-1586).


    3.2.4 Soil Classification


    Classifications attempt to render order out of chaos by setting up a
finite number of "pigeonholes" into which any individual can be placed.  When
a single pigeonhole is assigned, and thus all others are rejected, a good deal
of information about the individual is conveyed.  Soils, being very complex,
have been the subject of numerous classifications.  The "pigeonholes" used
consist of names, letter-number designations, or combinations of both.

    As with definitions, classifications and even identification of soils^are
colored by the  interest of the specialist  involved.  A very instructive dis-
cussion of the problem of classifying soils appears in Casagrande (1948).
Two-thirds of this article consists of discussions by other specialists of  the
classification  system designed by Casagrande which later became known as the
Unified Soil Classification System (USCS).  The USCS is widely used by founda-
tion engineers  in North America and is the one emphasized in this Handbook.
The other two systems mentioned are the textural classification of the U. S.
Department of Agriculture and the AASHTO system, commonly used by highway
engineers.  Reviews  of these three systems are found in Peck, Hanson, and
Thornburn (1974), and in the Asphalt  Institute Soils Manual (1978).
Gradation is a  basic  factor in all engineering soil-classification systems.
Figure 3-3 shows the  particle size limits  that have been assigned to  the
fractions of gravel,  sand, silt, and  clay  by various classification systems.
                                       3-8

-------
                                  FIGURE 3-3

               PARTICLE SIZE LIMITS OF SOIL FRACTIONS ACCORDING
                       TO SEVERAL CLASSIFICATION SYSTEMS
Classification
System fc
Bureau of
Soi/s, I8SQ-95

Atterberg, 1905

MIT, 1931

U.S. DeptAgr. ,1938

AASHO, 197O

Unified 1953
ASTM, 1967

Grain Size, mm j
o ig / o'j ooi aba aoa
Crave/ Sand
Silt Clay
I 0.05 &005
Grave/
Coarse Fine c -,.
sand sand *"*
Clay
2 0.2 0.02 0.002
Gravel
Sand
Silt
Clay
2 006 0.002
Gravel
Sand
Silt
Clay
2 0.05 0.002
\ Grovel
Sand
Silt
Cloy
\Colloids
75 2 OJO7S 00020.001
Gravel Sand
Fines (si/t$. clay}
75 4.75 0.075
              (from Peck, Hanson, and Thornburn, 1974; courtesy
              John Wiley & Sons, Inc.)
         3.2.4.1 Agricultural Classification
    Soil classification as practiced in agricultural soil science tends to
follow a taxonomic approach, into orders, families, etc., which are not of
interest to the cover designer, but which is the system used in soil survey
reports.  For naming of soils according to their mechanical composition, the
U. S.  Department of Agriculture uses a triangular chart whose vertices repre-
sent the extremes of sand, silt, and clay (Figure 3-4).  Particles larger than
2 mm in dimension are excluded; if a significant amount of such coarser mate-
rial is present, an adjective, "gravelly" or "stony," is applied to the soil
name.   The triangle is divided into fields with different soil names.   From
the mechanical analysis of the minus-2-mm portion of the soil the sand, silt,
and clay fractions (which must add up to 100 pet) are computed.  These frac-
tions correspond to some point in the triangle.  The soil is then named from
the field in which the point lies.
                                      3-9

-------
                                  FIGURE 3-4

                GUIDE FOR TEXTURAL CLASSIFICATION OF SOIL USED
                      BY U. S. DEPARTMENT OF AGRICULTURE
                    30>
  \/  y
  • SANDY~T~
.CLAY
X—X
/X
AM\
                                                    LOAM
                 20
                                \ X/^^^^^^^^^^^^^^^^A
                                V/\/\/\/\/\
       <§»
          SAND
                                   PERCENT SAND
                                                                  SILT
         3.2.4.2 Unified Soil Classification System
    The "Unified" soil classification system (USCS) is essentially the same as
the one developed during World War II by Professor A.  Casagrande of Harvard
University for use by the U.  S. Army in designing and building military air-
fields, and published by Casagrande (1948) as the "Airfield Classification"
system.  It was subsequently adopted with minor modifications by the Corps of
Engineers and the U.  S.  Bureau of Reclamation, and in 1969 it was adopted by
the American Society for Testing and Materials as a standard method, ASTM
D-2487.

    The USCS has two major divisions, the coarse-grained and the fine-grained
soils, and one minor division, the highly organic soils.   The coarse-grained
soils are further subdivided mainly on the basis of their gradation; the
fine-grained soils are subdivided on the basis of their plasticity character-
istics as indicated by Atterberg limits (see next section).  The structure of
the USCS is shown in Figure 3-5.  An important element is the Plasticity
                                      3-10

-------
              FIGURE 3-5

THE UNIFIED SOIL CLASSIFICATION SYSTEM

1 UNIFIED SOIL CLASSIFICATION
CRITERIA I

INFORMATION REQUIRED FOR
DESCRIBINO SOILS
TYPICAL NAMES
GROUP |
SYMBOLS
	 'R-
u _
u. :
i
1
» I
t ?
0 *-lJ
0 0
i
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.-
Aftrberg limits below Vl
or P I t*M »hon *
It
1
il
II
£ i
S
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. S
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3 01
ill!
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i
Not meeting all grodation require
Above V line with
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J are bordfrlme. c«M
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Atterberg limits bel
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i
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b S
3- E
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Wtifbtrg limit! Obo>rt '** l>n»
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sioqujAt onp (0 am
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Plastic tmei (lor ident ideation procedures
set CL below)
11HU
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( em t*»u » ON *m 0(
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unpeji ttjott) jo net) up
n ii
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2 *-' °
i|j| II j;
ft
ijj
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X
z
I
T.
s
1
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Inorganic Clays of Io* to medium plasticity, gravelly
Clays, sandy clays, ully clays, lean cMyt
Organic silts and organic Silt-cluyt 0* low
plasticity
i s
E _
3 <*»
1
Medium to high
Slight to medium
OS uenj 114
SAV13 OMff SltlC
Inorganic silts, micoceout or diatomaceoui tine
sandy or silty soils, elastic Silts
Inorganic clays of hiqh plasticity, fat clayl
i 5
l
1 %
S f
1
5)
I
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Chart, in the lower right, which is used in the identification process once
the liquid and plastic limits have been determined.   The "A" line on this
chart marks an empirical boundary identified by Casagrande (1948) between
inorganic and organic plastic clays and between inorganic clays and inorganic
silts.  It is defined by the equation:   PI = 0.73 (LL - 20).  Note also the
three simple field tests at the bottom of the chart, used for quick identifi-
cation of fine-grained soils.

    The USCS classifies soils into Groups, each designated by a two capital
letter symbol.   The letters are symbols pertinent to constituents or attri-
butes of the group.  Thus the following letter associations:  G, gravel; S,
sand; M, silt;  C, clay; Pt, peat; 0, organic; W, well (graded); P, poorly
(graded); H, high (liquid limit); L, low (liquid limit).  Note the mnemonic
significance of most of the symbols.  Thus for instance GVf is well-graded
gravel, SM is silty sand, and CH is clay (inorganic) of high liquid limit.

    An approximate correlation can be made between the USDA and the Unified
systems.  In Figure 3-6, USCS symbols have been superimposed on the triangular
textural chart, and in Table 3-1 corresponding designations in the two systems
are listed.   The reader should note that these are the usual correlations be-
tween USDA and USCS systems.  However,  other combinations are possible.  A
careful study of Figure 3-6 and Table 3-1 will show several cases of overlaps,
ambiguities, and missing groups; therefore, conversions can be only approxi-
mate.  The importance of the USCS from an engineering point of view is further
discussed below.

    Descriptions of specific procedures for classifying a soil according to the
USCS are given in the following manuals and designations:  ASTM, D-2487; USSR,
E-3; USCE, WES Technical Memorandum 3-357 (Geotechnical Laboratory, 1982).


         3.2.4.3 AASHTO Classification


    A third classification system in common use among highway engineers is
known as the AASHTO (American Association of State Highway and Transportation
Officials) (formerly AASHO) system.   Soils are grouped into seven classes, in
approximate order of quality as a highway subgrade (basement) material.
Groups A-l through A-3 comprise granular soils, groups A-4 through A-7 com-
prise silt-clay materials.  An eighth group comprises organic soils.  The sys-
tem is primarily based on mechanical analysis, but plasticity enters into the
classification of the silt-clay groups.  The system is presented in the AASHTO
Specifications volume (AASHTO Designation M-145) and discussed in the Asphalt
Institute Soils Manual as well as in texts on highway engineering and founda-
tion engineering.  Its structure is shown in Table 3-2.


    3.2.5 Soil  Tests


    To determine a soil property, it is usually necessary to perform one or
more tests.   Very little can be determined simply by visual observation.  The

                                      3-12

-------
                 FIGURE 3-6

COMPARISON OF USCS AND USDA SOIL TERMINOLOGY
        (FROM MEYER AND KNIGHT, 1961)
                  PER CENT SAND
                     3-13

-------
                                               TABLE  3-1

            USUAL CORRESPONDENCE  BETWEEN  USCS AND USDA SOIL  DESIGNATIONS
     (A)  USDA TEXTURAL  TYPES CORRESPONDING
	TO USCS SOIL DESIGNATIONS	
USCS
Soil
Type
USDA Soil  Types
 GW    Same as GP (except  well graded in grain
       sizes)

 GP    Gravel, very gravelly  sand  (less than
       5 percent silt and  clay)
 GM    Very gravelly sandy  loam, very gravelly
       loamy sand, very gravelly silt loam, very
       gravelly loam

 GC    Very gravelly clay loam, very gravelly
       sandy clay loam, very  gravelly silty clay
       loam, very gravelly  silty clay, very
       gravelly clay

 SW    Same as SP (except well graded in grain
       sizes)

 SP    Sand, gravelly sand  (less than 20 percent
       very fine sand)

 SM    Loamy sand, sandy loam; sand; gravelly
       loamy sand and gravelly sandy loam

 SC    Sandy clay loam, sandy clay; gravelly sandy
       clay loam and gravelly sandy clay

 ML    Silt, silt loam, loam, sandy loam

 CL    Silty clay loam, clay  loam, sandy clay

 OL    Mucky silt loam, mucky loam, mucky  silty
       clay loam, mucky clay  loam

 MH    Silt, silt loam (highly elastic, micaceous
       or diatomaceous)

 CH    Silty clay, clay

 OH    Mucky silty clay

 PT    Muck, peat
(B)   USCS  SOIL  TYPES CORRESPONDING
     TO USDA  SOIL TERMINOLOGY	
                                        USCS
                                        Soil
    USDA Soil Type                       Type
                                Gravel, very gravelly loam  sand



                                Sand


                                Loamy gravel, very gravelly sandy  loam,
                                very gravelly loam

                                Loamy sand, gravelly loamy  sand, sand

                                Gravelly loam, gravelly sandy clay loam


                                Sandy loam, gravelly sandy  loam
                                Silt loam, sandy clay loam (with fine-
                                grained sand)

                                Loam, sandy clay loam
                                Silty clay loam, clay loam

                                Sandy clay, gravelly clay loam, gravelly
                                clay

                                Very gravelly clay loam, very gravelly
                                sandy clay loam, very gravelly silty
                                clay loam, very gravelly silty clay

                                Silty clay, clay

                                Muck, peat
                                         GP,
                                         GW,
                                         GM

                                         SP,
                                         SW

                                         GM
                                         SM

                                         GM,
                                         GC

                                         SM
                                         ML
                                         ML,
                                         SC

                                         CL

                                         SC,
                                         GC

                                         GC
                                         CH

                                         PT
 Note:  Modified from Schomaker and Murdock  (1969)
                                                   3-14

-------
oo
 i
                                                               TABLE  3-2



                                 AASHTO CLASSIFICATION  OF SOILS  AND SOIL-AGGREGATE  MIXTURES


General Classification


Group Classification
Sieve Analysis, Percent
Passing
2.00 mm (No. 10)
0.425 mm (No. 40)
0.075 mm (No. 200)
Characteristics of Fraction
Passing 0.425 mm (No. 40)
Liquid Limit
Plasticity Index
Usual Types of Significant
Constituent Materials
S-;it~C1'v Materials
Granular Materials (More than 35%
(35% or less passing 0.075 mm) passing 0.075 mm)
A-7
A-l A-2 A-7-5
A-l -a A-l-b A-3 A-2-4 A-2 -5 A-2 -6 A-2 -7 A-4 A-5 A-6 A-7 -6


50 max
30 max 50 max 51 max
15 max 25 max 10 max 35 max 35 max 35 max 35 max 36 min 36 min 36 min 36 min


40 max 41 min 40 max 41 min 40 max 41 min 40 max 41 min
6 max N.P. 10 max 10 max 11 min 11 min 10 max 10 max 11 min 11 min
Stone Fragments Fine Silty or Clayey
Gravel and Sand Sand Gravel and Sand Silty Soils Clayey Soils
    General Rating as Subgrade
Excellent to Good
Fair to Poor
    Plasticity Index of A-7-5 subgroup is equal to or less than  LL minus 30.  Plasticity index of A-7-6 subgroup is greater than LL minus

    30  (see AASHTO Plasticity Chart).

-------
test may be a simple qualitative one or it may be very complicated.   Proper-
ties and tests will be discussed jointly in this section.

    The ultimate purpose of engineering soil  tests is construction.   A key
distinction needs to be drawn between design  tests and construction tests.
Design tests are performed to characterize the soil  and to determine what per-
formance may be expected from it under various conditions.   Characteristically
design tests are conducted in a laboratory, although some  important tests are
performed in the field.  The project design is based on the results of the
design tests, and is expressed in the project plans  and specifications.   Con-
struction tests, or control tests, are performed as  the project is built, and
are in fact acceptance or proof tests, whose  purpose is to assure that the
specifications are being met.   Construction tests need to  be simple, rapid,
and adapted to field use.   A comprehensive review of all  tests, both design
and construction, is given by Spigolon and Kelley (1983).

    The tests discussed in this section are design tests  and are listed in
Table 3-3.   Construction tests are presented  later in this Handbook.


         3.2.5.1 Gradation


    The gradation (mechanical  analysis; particle or  grain  size distribution)
of soils is determined by two complementary techniques, sieving for the
coarser particles and hydrometer analysis for the finer ones.   Sieving is a
direct technique in which the soil is shaken  through a nest of graded sieves,
and the fraction collected on each sieve is weighed.   In  the United States,
sieve numbers are based on the number of meshes, or  wires,  per linear inch.
Information on sieve specifications is given  in ASTM designation E-ll.  The
relation between particle sizes and numbered  sieves  is shown in Figure 3-7.

    Because it is not practical to sieve fine particles,  the hydrometer analy-
sis, an indirect technique, is used to determine the gradation of particles
finer than the No. 200 sieve.   This technique is based on  Stokes1 Law for the
settling velocity of .spheres in a viscous fluid.  The method is explained in
Taylor (1948) and other books on soil mechanics.

    The results of a mechanical analysis are  commonly plotted on a semi loga-
rithmic plot such as Figure 3-7.  The abscissa is grain size,  and the ordinate
is a cumulative weight percent finer than, or "passing,"  a given size.  The
amount within any given size range may be simply determined by finding the
abscissa points corresponding to the boundaries of that range, reading the
ordinates of the curve for those two values,  and subtracting the ordinate
values.

    A soil with a continuous range of particle sizes is called "well graded"
and is represented by a smooth grain-size curve with appreciable slope.  A soil
whose grains fall within a narrow size range is termed "poorly graded" and is
characterized by a steep grain-size curve.  A soil with appreciable coarse and
appreciable fine grains but lacking in intermediate ones is termed "gap-graded"
or "skip-graded" and is characterized by a "steplike" grain-size curve.

                                      3-16

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                                   TABLE 3-3

            MANUAL DESIGNATIONS OF SELECTED ENGINEERING SOIL TESTS

Test
Gradation {Mechanical Analysis)
Water Content
Specific Gravity
Liquid Limit
Plastic Limit
Shrinkage Limit
Relative Density
Standard Proctor Compaction
Modified Proctor Compaction
One-Dimensional Consolidation
Strength Tests
Permeability
Shrink/Swell Behavior
ASTM
D-422a
D-2216
D-854
D-423
D-424
D-427
D-2049
D-698
D-1557
D-2435

—
D-3877
AASHTO
T-88
—
T-100
T-89
T-90
T-92
—
T-99
T-180
T-216
b
See Table
—
USBR
E-6
E-9
E-10
E-7
E-7
E-7
E-12
E-ll
—
E-15

3-4
—
USCE
Appendix V
Appendix I
Appendix IV
Appendix III
Appendix III
Appendix III
Appendix XII
Appendix VI
Appendix VI
Appendix VIII


Appendix VI I I -A

 Other specialized ASTM designations relate to gradation.

JThere are many different strength tests with varying special applications.
 Certain strength tests yield the Modulus of Elasticity from which the flex-
 ibility of the cover can be evaluated.  For strength tests consult the refer-
 enced manuals.
     Manuals referred to in this table are the following:
  ASTM:  "Part 19:  Soil and Rock; Building Stones" of the "Annual Book of
ASTM Standards," published annually by the American Society for Testing and
Materials, Philadelphia, PA.
  AASHTO:  "Standard Specifications for Transportation Materials and Methods
of Sampling and Testing," published every four years by the American Associa-
tion of State Highway and Transportation Officials, Washington, DC.
  USBR:  "Earth Manual," 2nd edition (1974), published by the Bureau of
Reclamation, U. S. Department of the Interior.

  USCE:  "Laboratory Soils Testing," Engineer Manual EM 1110-2-1906 (1970;
revision issued 1980), published by the Office of the Chief of Engineers,
U. S. Department of the Army.

                                      3-17

-------
                                        FIGURE  3-7

              GRADATION CURVES OF  SOME  SANITARY-LANDFILL COVER SOILS
   U. S. STANDARD SIEVE OPENMG IN INCHES         U. S. STANDARD SIEVE NUMBERS
  .,4  3   2     1	  	3  4  6  I 10  14 16  20 30  40  50  70 100 140 200
                                     1    05
                                 GRAIN SIZE IN MILLIMETERS
                                                     01    OOS
                                                                      0.01  0.005
SAMPLE NO.
1
2
3
4
5
6
7
ELEVATION
OR DEPTH
MISSION CANYON,
CALIFORNIA
TACOMA. WA
HAZLEHURST, MS
CENTRALIA, WA
VICKSBURG, MS
KENT HIGH LANDS,
WASHINGTON
DALLAS, TEXAS
(WALNUT HILLS)
CLASSIFICATION
SANDY GRAVEL (GP)
GRAVELLY SAND (SW)
CLAYEY SAND (SC)
SANDY SILTY CLAY (CL)
SILT (ML)
CLAYEY SILT (ML)
FAT CLAY (CH)
NATW*
10.8
3.0
12.0
30.5
18.0
27.3
34.9
LL
PL
NON-PLASTIC
NON-PLASTIC
21.0
40.0
30.0
33.1
68.0
12.0
21.0
26.0
24.7
27.0
PI


9.0
19.0
4.0
8.4
41.0
                                                                                      0001

GRAVEL
COARSE | FWC
SAND
COMSE | MCDttm
FINE
SILT OR CLAY
(from Schomaker  and Murdock,  1969,  and  Lutton,
Regan and  Jones,  1979)
                                             3-18

-------
    Certain characteristic points on the grain size curve have been given
special attention.  The 10-pct-finer point, designated D10, is termed the
effective size.  The ratio D60 (60-pct-finer size) to D10 is termed the
uniformity coefficient (or coefficient of uniformity)  C  .  These and other
parameters derived from the gradation curve are discussed in Peck, Hanson, and
Thornburn (1974), the Earth Manual (USBR, 1974), and elsewhere.  See also
Spigolon and Kelley (1984).

    The hydrometer analysis is a slow, somewhat laborious process, and not of
overriding importance in most engineering considerations.  Soil classification
according to the USCS, an important factor in soil-based design, considers
only the plasticity characteristics, and not the gradation, of the fines por-
tion of a soil.  Hydrometer analysis is sometimes useful in permeability cor-
relations, however.

    Manual designations pertaining to mechanical analysis are listed in
Table 3-3.
         3.2.5.2 Atterberg Limits


    Early soil classifications were based only on mechanical composition, but
important variations in soil behavior were not accounted for by a strictly
mechanical classification.  This led A. Atterberg (1911) to develop the simple
tests based on moisture content that bear his name.   The Atterberg limits are
the liquid limit, the plastic limit, and the shrinkage limit (abbreviations:
LL, PL, SL) (other symbols have been used such as  W.  , Wp  , W<. ).

    Two important points should be kept in mind regarding Atterberg limits.
(1) They apply only to fines:  either fine-grained soils or the fines portion
of graded coarse-grained soils.   (2) They concern themselves solely with water
content; no other basic soil property is involved.  These facts reflect an
important fact regarding water in soils.  In coarse-grained soils,  water is a
passing component, which may or may not be present.   In fine-grained soils,
water is an essential component, which is nearly always present; moreover
water plays a fundamental role in determining these soils'  behavior.

    The Atterberg limits are expressed as numbers, usually not reported to
more than two significant figures, representing simply water-content values
below and above which different types of behavior prevail.   The limits are
derived from simple, standardized tests which require a slight amount of per-
sonal judgment; hence no greater precision than two significant figures is
warranted.  The liquid limit states the water content above which a soil be-
haves like a liquid, but below which it behaves plastically.  The plastic
limit states the water content below which the soil  starts to behave like a
solid, and above which it behaves plastically.   The shrinkage limit is the
water content below which further loss of water by evaporation does not cause
a further reduction in volume.   Above the SL, changes in water content are
associated with changes in volume.  Although the Atterberg limits are strictly
empirical, there is vast correlation experience with them.


                                      3-19

-------
    Since the LL and PL define respectively the upper and lower bounds of
plastic behavior, the interval between them may be termed the plastic range.
The size of this interval  is designated the plasticity index (PI),  which is
defined simply as the difference between the liquid and plastic limits (PI =
LL - PL).

    The liquid limit is determined by means of a simple but specially designed
laboratory device, shown in Figure 3-8.   This device possesses a shallow,
bowl-shaped brass cup, into which the moist soil is packed.   Into the smoothed
surface of the specimen within the cup a groove of specific dimensions is cut
with a standardized grooving tool.   As the handle is rotated the cup is raised
and dropped repeatedly.  When a specified length of the groove just closes,
the number of drops or blows is recorded; the specimen water content is then
determined.
                                  FIGURE 3-8

                  APPARATUS FOR DETERMINATION OF LIQUID LIMIT

                                            B
                                                            l.6mm
                (Note:  a slightly different grooving tool
                is specified by ASTM and AASHTO.)  (Courtesy
                of John Wiley & Sons, Inc.)
    To determine the LL a series of tests at different water contents is con-
ducted and a curve of blow count versus water content plotted.  The LL is
arbitrarily defined as the water content corresponding to 25 blows.

                                      3-20

-------
    The plastic  limit determination  involves  a  simple procedure of  rolling a
thread of plastic  soil between one's  hand and a glass plate.  When  a  1/8-in.-
diam thread of soil just begins to crumble, the soil is at  its plastic  limit.

    The shrinkage  limit is determined by a procedure involving weights  and
measured volumes of the soil  in a saturated and a dried-out condition.  A
simple explanation may be found in Taylor (1948).  The shrinkage limit  is less
often used than  the other limits.

    Atterberg limit tests are also called soil consistency tests.    Descrip-
tions of specific procedures  for these tests  are given in the technical man-
uals listed in Table 3-3.
         3.2.5.3 Water Content and Specific Gravity


    Specific test methods for water content and specific gravity of soils are
given in the technical manuals listed in Table 3-3.  These properties have
already been defined and discussed above under "soil properties."


         3.2.5.4 Density


    Soil density is a function of several factors.  A basic factor is the spe-
cific gravity of the soil grains.  Usually, however, this varies over the nar-
row range of 2.5 to 2.8.   Another factor is the packing or disposition of the
soil particles.   If soil  grains were uniform spheres, their densest possible
packing would comprise a void ratio of .35 (26 percent porosity).  If smaller
spheres were also present, the void ratio would be decreased.   It can be
appreciated that grain size distribution may noticeably affect soil density.
A third factor is the shapes of soil grains.   Spheres, either of uniform size
or of a gradation of sizes, could be relatively readily vibrated into a dense
condition.   Sharp, angular particles would more actively resist rearrangement.
Platy particles could in principle be stacked very densely if they were all
uniformly aligned.  From a random orientation, however, it might be very dif-
ficult to bring them into a uniform alignment.  A fourth factor, water con-
tent, strongly affects density as discussed below.

    With soil grains of a particular specific gravity, soil density can be
increased only by compaction.   Compaction involves densification of the grain-
to-grain structure and expulsion or compression of trapped air.   Increasing
the soil density produces several practical and beneficial changes.  Stability
against future settlement is increased,  as the potential for densification has
already been partially exhausted.  Strength,  or resistance to shearing defor-
mation,  is  increased, because the potential for intergranular movement has
been partially exhausted.  Permeability is decreased, because in reducing the
void ratio  the available  flow channels have been made smaller.

    Various construction  methods and equipment are used in practice for soil
compaction.   Some are better adapted to granular soils, others to fine-grained

                                      3-21

-------
cohesive soils.   Compacting equipment is discussed later in this Handbook.   In
general, vibration techniques and smooth-wheeled rollers are better suited to
granular soils,  and tamping rollers such as sheepsfoot rollers are more
adapted to cohesive soils.   Smooth-wheeled rollers include machines with both
steel wheels and rubber tires.   Besides the type of equipment, the weight of
the equipment obviously influences the degree of compaction produced.

    Two types of laboratory tests are used to determine reference densities of
soils, the compaction ("Proctor") test and the relative density or maximum-
minimum density test.  Good discussions of the principles of these tests and
the soil types to which each is applicable are given in the Earth Manual
(USBR, 1974) and Peck, Hanson,  and Thornburn (1974).   In general, the relative
density (maximum-minimum) test is applicable to granular, cohesionless, free-
draining soils,  and the Proctor compaction test is applicable to silty and
clayey soils of all types.   Both tests provide reference values against which
field-achieved densities can be compared and critically evaluated.

    The relative density test consists of placing the dry soil in a test con-
tainer in a loose state and then in a dense state, using previously defined
procedures.  The densities determined are respectively designated zero and
100 percent relative density.  Loose placement is achieved by a specified
gentle pouring action, and dense placement by vibration under specified condi-
tions for a specified time.  The actual dry bulk densities in the two limiting
states are then determined.  The relative density of any other specimen of the
soil is calculated with a simple formula relating its dry bulk density to the
two limiting values (see equation 3.9 above).

    Compacted granular soil is generally used as a bearing member, that is, as
a foundation.  In a cover system, this would most likely be in the foundation
or buffer layer (see below).  An accepted lower limit for densified granular
soil is 70 percent relative density (Earth Manual, p 280.)  References to
relative density test procedures are given in Table 3-3.

    The compaction or moisture-density test is commonly known as the Proctor
test, after R. R. Proctor, who first proposed it in 1933.  It is based on the
fact that for a given soil and a given compactive effort, the degree of com-
paction achieved is found to be a function of water content.  At some inter-
mediate water content, maximum compaction, as measured by maximum dry density,
will be achieved.  If the soil is either wetter or drier, the same amount of
compactive effort will produce a lower density.  An example of this effect is
seen in Figure 3-9.

    The peak of the compaction curve denotes the optimum water (or moisture)
content and the maximum dry density (or dry unit weight).  These terms are
extensively used in specifications for construction control, as discussed
below.  A "zero air voids" curve is usually drawn above a compaction curve, as
shown in Figure 3-9.  Such a curve is readily computed if the specific gravity
of the soil grains is known, and represents complete expulsion of air, leaving
only water in the soil pores.  It represents the upper limit for densification
by compaction.
                                      3-22

-------
                                   FIGURE  3-9

               TYPICAL COMPACTION  (MOISTURE-DENSITY)  TEST  RESULT
               108
               106
               104
                102
               100
                         16
                                 18
                                         20

                                    WATER CONTENT. %
                                                 22
                                                         24
               (from  Standard  Proctor test on a CL soil  according
               to  Unified  soil  classification system)
    The Standard Proctor test involves 12,375 foot-pounds of compactive effort
per cubic foot of soil (a 5.5-lb compacting rod dropped through a height of
12 in. a total of 75 times, that is, 25 blows per lift for each of three
lifts, on a soil specimen 1/30 cubic foot in volume).  The USER uses  slightly
different test dimensions, but the effective effort  is the same.  Another
standardized test, termed the Modified Proctor test, involves approximately
4-1/2 times as much input effort, through a heavier  rod and a higher  drop.
The Standard test, developed by R.  R. Proctor, modeled compactive efforts pro-
duced by field construction equipment in the early 1930's.  The Modified test
modeled heavier equipment developed later for use on airfields.  An instruc-
tive discussion is given by Lutton, Regan and Jones  (1979) on the use of tests
with lower effort than the Standard Proctor test for modeling the generally
lower efforts applied in landfill compaction.  References to detailed test
procedures are given in Table 3-3.

    It is important to remember that a compaction curve, such as Figure 3-9,
applies only for a specific compaction method.  A different procedure applied
to the same soil will shift the curve both vertically and laterally.  A
                                      3-23

-------
greater compactive effort will yield a higher maximum dry density at a lower
optimum moisture content.

    The principle of construction control by means of moisture and density is
illustrated by Figure 3-10.   Assume that a given soil has been tested in the
laboratory by the Standard Proctor test, and that the compaction curve shown
is the result.  Optimum moisture content is 18.8 pet, and maximum dry density
is 106.2 pcf.  Assume further that the soil has been tested for some property
of interest, say permeability, at different conditions of dry density and
water content, and permeability satisfactory for project purposes has been
found to exist at dry density greater than 102 pcf and within a moisture range
of 16.8 to 21.8 pet.  The compaction curve shows that a density of 102 pcf can
be achieved, using standard compaction, within the moisture-content range from
15.3 to 22.9 pet.  The cross-hatched field in Figure 3-10 indicates the range
of acceptable conditions for the compacted soil.  Now 102 pcf is 96 percent of
106.2 pcf, the maximum dry density.  If performance or end-result specifica-
tions are used, they will be written to say that compaction of this soil must
be to a minimum of 96 percent of maximum dry density within a range from 2 pet
dry to 3 pet wet of optimum moisture content, based on the results of the
Standard Proctor compaction test.  In this way, laboratory compaction informa-
tion is translated into simple specifications which the contractor can apply
in the field.

                                  FIGURE 3-10

                   RELATION BETWEEN LABORATORY TEST RESULTS
                   AND STANDARD CONTRACT SPECIFICATIONS FOR
                             COMPACTION (SEE TEXT)
               108,
                 14
                        16
18       20

  WATER CONTENT,
                                                22
                                       3-24

-------
    A clear explanation of construction control  using  compaction  tests  and
criteria is given by Hilf (1974b).  Useful  discussion  of  various  test methods
is given by Spigolon and Kelley  (1984).   Figure  3-11 represents data from
three projects of the USBR.  Laboratory compaction  curves are  compared  with
curves of actually placed fill.  Note that  the laboratory curve gives an
approximate prediction of field  results,  but  the laboratory  curve can be
either high or low, relative to  the field.  Note also  the variability of
moisture-density relations among the three  soils.
                                  FIGURE  3-11

               FIELD AND LABORATORY COMPACTION  CURVES  FOR  SOILS
               PLACED IN DAM EMBANKMENTS  OF THREE  USBR PROJECTS
                               (FROM HILF, 1974b)
IJ4
132
130
128
126
122
120
118
114
112
no
108
104
102









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                «   T  I   >   10  II  12   13  14  IJ   l«  17  IB  19   20  21
                           WATER  CONTENT - PERCENT DRY WEIGHT
    Compacted soils are generally placed at a moisture content  near  optimum.
The following effects are true, however:  maximum as-placed  soil  strength  is
developed dry of optimum; maximum soil  impermeability is  developed wet  of
optimum; maximum density, of course, is at optimum.
                                      3-25

-------
         3.2.5.5 Strength


    Strength of materials includes tensile, compressive,  and shear strengths.
Soils effectively have no long-term tensile strength,  and since most soils
fail in shear, for all practical purposes strength of  soils means their shear-
ing strength.

    From the cover designer's standpoint, the only reason for concern with
soils'  shearing strength, other than for trafficability purposes while the
cover is being constructed, is where there is a threat of slope failures.
Lutton, Regan, and Jones (1979) have discussed the problem of slope stability
with regard to cover installations, and reviewed pertinent tests.  There is no
reason to amplify their discussion in this Handbook, other than to point out
one or two general facts.

    The subject of slope stability in soils is complicated and has received
much study and research.  It would be misleading to suggest that a Handbook of
this nature could give more than general guidance if a potential slope-
instability problem is suspected.   A manual dealing with the matter that has
been widely used in both governmental and private practice is Department of
the Army, 1970.

    One simple yet valid statement is that in virtually all cases, water is
the leading "bad actor" in causing slope failures.  Slopes tend to fail under
conditions of high ground moisture.  This may be seasonal, due to prolonged
rain or heavy snowmelt; it may be situational, as when quick drawdown of a
reservoir leaves a saturated earth embankment; it may be a result of poor
design, as where slope drainage should have been provided for, but was not.

    Taylor (1948) gives a very clear and thorough explanation of the factors
involved in slope stability and in the shearing strength of soils.  Peck,
Hanson, and Thornburn (1974) discuss factors affecting slope stability, and
soil strength tests that may be applied in slope-stability studies.  They
state, however (1974, p 101):  "The shear strength of soils, in spite of
extensive research, remains a complex and controversial subject; the vast
literature is confusing even to the specialist."

    In view of the above, it is recommended that any slope-stability problem
at a hazardous waste site be referred to a competent and recognized geotechni-
cal expert.

    There are many different soil strength tests with varying applications.
However, because these tests are not directly applicable to cover soils, they
are not listed in this Handbook.  For names and designations of  soil strength
tests the reader should consult the technical manuals listed in Table 3-3.
         3.2.5.6 Consolidation


    Consolidation refers to a process of densification of a soil under load,

                                      3-26

-------
accomplished through a slow escape of water from the pores.  It will be of
little concern within the  soil of a cover system.  It may well be of concern
in the waste itself, however, or in the soil underlying it.  Consolidation is
of importance to the foundation engineer, because it controls the settlement
that will occur beneath his structures.  If some parts of a structure settle
more than others (differential settlement), the structure will tend to deform
and perhaps crack.  Susceptibility to consolidation is termed "compressibil-
ity."  Consolidation and subsidence of wastes is the subject of current EPA-
sponsored research.

    Compressibility of soils is tested in a device called the consolidometer,
and the test is commonly called the one-dimensional consolidation test.  Man-
ual references are cited in Table 3-3.

    Consolidation commences when a load, such as a structure, is imposed on a
soil.  Before the load is  placed, the soil is in equilibrium, that is, it is
fully consolidated with respect to the force system in effect.  The soil is
neither settling nor swelling.

    The imposition of a load (or conversely the excavation of a mass of soil)
introduces a new force system, and there is an immediate tendency to adjust to
it.  The process of consolidation commences.   The rate of consolidation is
controlled directly by the permeability of the soil, whereas the ultimate
amount of consolidation is related to the compressibility of the soil skeleton
and thus to the nature of  the soil  particles.   As an illustration of the rate
effect, see Figure 3-12(a) and (b), showing typical time curves for laboratory
consolidation of a sand and clay.   The sand responds very fast and the process
is nearly complete in a short time.   The clay responds much more slowly and
the process continues over a long time.   In both cases the rate is greatest
initially and decreases progressively thereafter.

    Because of the direct  relation  between consolidation rate and permeabil-
ity,  the latter can be computed from data from a consolidation test.   This is
not commonly recommended,   however.

    Natural  soils have,  as a rule,  been in place for many years or centuries,
and thus are consolidated  to equilibrium under their local force system.
Waste dumps, on the other  hand,  were formed relatively recently and are likely
still  to be in the process of consolidating.   Moreover,  materials in the waste
may be decomposing.   Waste dumps may be inherently susceptible to differential
consolidation.   In a discussion of  "inadequate foundations," the Earth Manual
(USER,  1974b) lists several categories,  one of which is  "talus piles, spoil
piles,  and dumps."   The loose and random manner in which material  is placed in
these deposits leads to their poor  quality as  foundations.  Unfortunately,
uncontrolled waste sites  fall  directly into this category.  Thus subsidence,  a
recognized serious threat to the integrity of  cover systems, is probably to
some  degree inevitable.   Careful  placement and compaction of the buffer or
foundation layer of the cover system is probably the best way to mitigate the
problem.
                                      3-27

-------
                  FIGURE 3-12

TIME CURVES FOR A TYPICAL LOAD INCREMENT IN A
LABORATORY CONSOLIDATION TEST:  (a)  FOR SAND,
               AND (b)  FOR CLAY
u
<£ 20
d)
o
*40
.9
860
&
5 80
100
(




V
)

























123456
Time in minutes
    2200 I
    2000
   BO
   §1800
   .s
   •o
    1600
    1400
                       (a)
                                  One-day reading^
                    10     15     20
                      Time in minutes
25
30
                       (b)
   (from Taylor,  1948; courtesy John Wiley &
   Sons, Inc.)
                       3-28

-------
         3.2.5.7 Permeability


    Permeability may be the most important property of cover soils, inasmuch
as the principal purpose of the cover system is to act as a roof and retard
the inflow of water.  Permeability is a measure of the ease with which fluids
may flow through a soil.  Permeability is related to porosity, the capacity of
a soil to hold fluid, but it is related to many other factors as well.   Per-
meability is concerned with time, whereas porosity is not.  Permeability is
directly analogous to electrical conductivity, thermal conductivity, or simi-
lar material properties with regard to any other type of flow.

    Permeability has been extensively discussed in the literature of civil
engineering, ground-water hydrology, and petroleum engineering.   The latter
field is concerned with more than one type of fluid, whereas the former two
deal in general only with water.  When multiple fluids are involved, one must
deal with the intrinsic permeability, which is determined only by attributes
of the porous medium.  Significant attributes are those pertaining to flow
channels through the medium:  size of channels, their shape with regard to
both cross section and tortuosity, surface roughness, and other surface fac-
tors such as electrostatic conditions.   By channels, of course,  is meant the
enormous number of possible flow paths within the soil pores.   The unit of
intrinsic permeability is the darcy, and its dimensions are length squared
(e.g., cm2, ft2).

    When a fluid in contact with soil is capable of reacting with the soil
particles, a complicating effect is introduced, since such interaction may
actually change the intrinsic permeability by changing the soil  structure.
This is a subject of great current interest with regard to the use of clay
liners for waste or other liquid impoundments.

    Rate of flow of a given fluid depends on properties of the fluid, most
importantly viscosity, as well  as on properties of the medium.  By specifying
a given fluid at a given temperature, such factors as viscosity and fluid den-
sity are fixed, and it becomes  possible to define a simple coefficient for the
permeability of a given soil to that fluid.   The coefficient of permeability
is so defined, the fluid being  water at 20°C.   In ground-water hydrology the
term "hydraulic conductivity" is used;  it is precisely synonymous with coeffi-
cient of permeability as here defined.   The conventional symbol  in soil
mechanics for coefficient of permeability is (lower case)  k  (in ground-water
hydrology, upper case  K  is used for hydraulic conductivity).  The factor
k ,  commonly simply called the  permeability, is the (sole) soil-dependent term
in the simple equation known as Darcy's law, which describes laminar fluid
flow through porous media.   Thus Darcy1s law is:

         Q = kiA        with terms as follows:

         Q = a volumetric flow rate
         k = coefficient of permeability
         i = hydraulic gradient
         A = an area normal to  the mean direction of flow
                                      3-29

-------
    Hydraulic gradient  i  is a potential gradient, a measure  of  the  driving
force associated with the flow.  It is the quotient of the difference in
(total hydraulic) head between any two points divided by the linear distance
between the points.*  Being the quotient of two linear quantities, it is  di-
mensionless.  As can be seen from the dimensions in Darcy's law,  k  has the
dimensions of a velocity.  It is in fact, however, a volumetric flow  rate
passing through a finite area, and it is well to keep this fact in mind.   The
velocity identified by a given  k  is sometimes termed the superficial veloc-
ity, in contrast to the seepage velocity, the actual mean speed with  which
water is moving through the soil.   It is a simple matter to understand that
the superficial velocity stands to the seepage velocity as the pore volume of
the soil stands to the total volume, thus:


                          superficial     ,       ...
                         —y*	 = n (= porosity)
                            seepage

This relationship is illustrated in Figure 3-13.   Furthermore, it is  neces-
sary, strictly speaking, to use the effective porosity, that is, the  volume
fraction of those pores that actually participate in flow.   Particularly  in
very fine soils, much of the pore space may be effectively "dead storage," as
a result of electrostatic or chemical binding of the water in place.   Thus the
seepage velocity will always be faster, and may be much faster, than  the
superficial velocity.

                                  FIGURE 3-13

             SKETCH SHOWING RELATION BETWEEN DARCY ("SUPERFICIAL")
                  VELOCITY  V  AND SEEPAGE VELOCITY
      PIPE CROSS-SECTIONAL     SOIL                    PISTON MOVING TO RIGHT
      AREA A                 POROSITY n        ,,*mvn    / AT VELOCITY V
            A	!T	!T    7
                             1  • V   :    ,  '  Mi
                    WATER -*"  |

                   	I  '
                WATER PLOWS TO RIGHT AT VOLUMETRIC FLOW RATE Q.

                Q  = V A .    WITHIN SOIL, WATER MOVES TOWARD RIGHT

                AT MEAN VELOCITY Vseep&ge =  \ . v  _
   Among the many explanations of seepage and other hydraulic phenomena in
  soil,  one of the clearest is by Taylor (1948).

                                      3-30

-------
    In civil engineering   k   is customarily expressed  in centimeters per sec-
ond.  However, several other  units are in use.  One  is the meinzer, used by
the U. S. Geological Survey and denoting gallons per day per square foot.
Others that may be encountered are inches per hour,  feet per day, etc.  All
permeability units expressed  in velocity or volumetric-rate-per-area units can
easily be reduced to centimeters per second.

    Permeability is a very simple property to conceive but may be a very in-
tricate one to deal with in fact.  For one thing, in contrast to many other
properties, it varies over enormous ranges.  Another difficulty relates to the
fact that a measured permeability is an average, describing the average flow
over perhaps millions of flow channels.  If one large  channel develops, as by
a crack or erosion of a tube  through the soil, the flow may increase suddenly
by many-fold.  In testing  for permeability, it is essential that no anomalous
large channel be present.  Thus, if a permeability test is carried out in a
cylinder, it is essential  that no flow-channel be available along the cylinder
walIs.

    Permeability may be and commonly is anisotropic, thus, greater in some
directions than others.   Permeability relates to flow channels, and thus to
the structure of a sediment or soil.   Where platy mineral grains are present
(recall that the clay minerals form platy grains) there is a tendency toward
horizontal orientation.   Natural soil deposits commonly show higher permeabil-
ities horizontally than vertically; the factor may be as high as 102 or even
103 (USBR, 1974b, p 59), although it is usually less (Olson and Daniel, 1981).
In natural deposits, gross layering of different beds contributes strongly to
the greater horizontal flow capacity.   Remolded soils may tend more toward
isotropy; but placing and compacting in layers introduces a definite horizon-
tal bias, which,works in favor of the cover designer, whose main interest is
in reducing vertical permeability.

    Consider the effect of thickness of a clay barrier layer.   Darcy's law
shows that the volumetric flow rate for a given area depends only on permea-
bility and hydraulic gradient.  The gradient for percolation is constant at
unity.   Therefore,  the flow rate is a function solely of the permeability.
Thus, for steady-state saturated conditions, the same flow rate or flux would
pass through a 2-in.-thick layer or a 20-ft layer of the same material.   An
advancing wetting front, however, would take longer to reach the bottom of the
thicker layer,  the transit times being proportional  to the thicknesses.   The
rate of movement of a wetting front should correlate approximately with the
seepage velocity, mentioned above.   The thicker layer, of course,  would be
more stable and durable.   And since steady-state saturated conditions will
virtually never really occur,  the delay provided by the thicker layer provides
more time for drainage of the soil  by evapotranspiration and for the bene-
ficial  effects of unsaturated flow (discussed below).

    Darcy's law is quantitatively valid for saturated flow under laminar con-
ditions.   Such conditions represent a state of complete regularity.   Devia-
tions from Darcy flow occur in two separate directions.  On the high-flow side
is turbulent flow,  on the low-flow side is unsaturated flow.
                                      3-31

-------
    Turbulent flow occurs with Reynolds numbers above a certain value (consult
texts in soil mechanics or hydraulics).  Turbulent flow may occur in very
coarse-grained soils, such as the drainage layer of a cover system.   Under
saturated turbulent flow, the volumetric flow rate falls off fractionally from
the Darcian value.   Very large flow rates are still likely, and this condition
presents no problem.

    Unsaturated flow is a much more realistic expectation in cover systems.
Unsaturated flow may be conceived of as a situation where only a fraction of
the possible flow channels in a soil are being utilized.  Measurements of
permeability for unsaturated conditions are complicated but have been per-
formed.   A typical  result of such measurements is shown in Figure 3-14.   As
the degree of saturation decreases, the apparent permeability of the soil
falls off sharply.   Just as with the air-bubble effect mentioned below,  this
effect works to the advantage of the cover designer in practice.   A clay cover
will probably seldom be completely saturated.  Thus the effective permeability
of the soil will usually be less than the nominal permeability derived from
tests conducted under saturated conditions.

    A primary source of error in laboratory permeability measurements is the
evolution of air bubbles from the water which block soil pores and artifici-
ally reduce permeability.  For this reason good laboratory procedure requires
the use of deaired water.  In practical field use in a cover system, this
effect works to the advantage of the cover designer.   In fact it may be a
prime contributor to the lower effective permeability governing unsaturated
flow.

    Permeability tests may be made by either the constant-head or the falling-
head technique.   In the constant-head technique the test is run at steady-
state conditions, all the terms in Darcy's equation except  k  are measured; k
is solved for.   In the falling-head technique the driving head, and therefore
the flow, are both allowed to decay exponentially with time; using the
exponential-decay law and making two or more joint measurements of head and
time make it possible to compute  k .   Sketches illustrating the two tech-
niques are given in Lutton, Regan, and Jones (1979) and elsewhere.   The
constant-head method is appropriate for higher flow rates and thus more per-
vious soils; the falling-head method is suited to lower flows and less per-
vious soils.

    It may be noted that a permeability test does not involve arbitrary stand-
ard procedures,  equipment, or numbers (cf.  Liquid Limit test, Proctor compac-
tion tests).  Therefore, any apparatus that properly measures flows and heads
is capable of yielding correct permeability values, so long as complicating
factors such as air-bubble evolution and wall leakage are recognized and
accounted for.   Thus, permeability tests are not as highly standardized as
some other tests.

    The very small  permeability of highly impervious soils may be quite diffi-
cult to measure accurately.  The situation is somewhat analogous to that of
quantitative chemical analysis.  Components that are present in parts-per-
million or parts-per-bi11 ion ranges may require different and more exacting
techniques than those present in larger quantities.  A listing of published

                                      3-32

-------
                            FIGURE 3-14


          EFFECT OF DEGREE OF SATURATION ON PERMEABILITY
 1.0
   .8
E.6
w
P-C
u
OS
   .2
      k  =
       r

      S  =
        u
                20
relative permeability =


degree of saturation, ratio


degree of saturation at irre-

 ducible minimum (specific

 retention), ratio


unsaturated permeability


saturated permeability
                 40          60


             SATURATION, IN PERCENT
100
 Experimental data for permeability of 20-mesh Del Monte sand, and


 calculated permeability from equation  k  =   (S - S )/(! - S )


 (from Johnson and Kunkel, 1963)
                                3-33

-------
permeability-test procedures is given in Table 3-4,  but it should be noted
that permeability testing is less well  standardized  than other tests, partic-
ularly at the low-permeability end of the range.   Before a given test is used,
it should be carefully noted for what types of soil  that test is valid.   For
instance, the standard permeability test described by ASTM and AASHTO (see
below) is specifically limited to granular soils,  down through the range of
fine sand and silt.   These organizations have no published permeability test
pertaining to clays.   The current most-favored laboratory test method for per-
meability of clays involves a rubber confining membrane, similar to that used
in triaxial shear tests.   This technique is described in USCE (1980).  Permea-
bility of clays may also be measured in the consolidometer (USCE, USBR).  Sev-
eral papers dealing with permeability measurement were presented at an ASTM
symposium on impermeable barriers for soil and rock held in June 1984 in
Denver, CO.

    More reliable information on permeability may be derived from field than
from laboratory tests.  The tests in Table 3-4 include three field tests, all
from the Earth Manual (USBR, 1974b).  These tests are simple, and have limita-
tions as mentioned by Auvinet and Espinosa (1981); moreover they take time,
and require the extended presence of a technician in the field.   Nevertheless,
their use may be warranted.  Field permeability may also be measured using
methods developed by Hvorslev (1949) and presented in Lambe and Whitman
(1969).

    The special difficulty in measuring very low soil permeabilities was ac-
knowledged by ASTM with the publication of Special Technical Publication 746,
"Permeability and Groundwater Contaminant Transport" (Zimmie and Riggs, 1981),
devoted to the subject.  A paper in this volume by Olson and Daniel (1981)
addresses directly the problem of measurement of low permeabilities, discuss-
ing pitfalls and problems as well as various methods that have been used.
Another paper in the volume (Auvinet and Espinosa, 1981) describes a case his-
tory of the design and construction, including permeability testing, of a
clay-lined cooling pond.   In the opinion of the preparers of this Handbook,
the insights provided in Auvinet and Espinosa's paper are especially enlight-
ening for anyone concerned with the field use of compacted clay in a water-
retarding application.

    Permeability test procedures described in standard manuals are listed in
Table 3-4.  Conversion factors between various permeability units may be found
in Table 3-5.
                                      3-34

-------
                                   TABLE 3-4

                          STANDARD PERMEABILITY TESTS

Manual
ASTM
AASHTO
USBR
USBR
USBR
USBR
USBR
USBR
USCE
USCE
USCE
USCE
USCE
USCE
Designation
D-2434
T-215
E-13
E-14
E-15
E-18
E-19
E-36
App. VII (3)
App. VII (4)
App. VII (5)
App. VII (6)
App. VII (7)
App. VII (8)
Title of Test
Permeability of Granular Soils
(Constant Head)
Permeability of Granular Soil
(Constant Head)
Permeability and Settlement of Soils
Permeability and Settlement of Soils
Containing Gravel
One-dimensional Consolidation of Soils9
Field Permeability Tests in Boreholes
Field Permeability Test (Well Permea-
meter Method)
Field Permeability Test (Shallow-well
Permeameter Method)
Constant-head Permeability Test with
Permeameter Cylinder
Falling-head Permeability Test with
Permeameter Cylinder
Permeability Tests with Sampling Tubes
Permeability Tests with Pressure
Chamber
Permeability Tests with Back Pressure
Permeability Tests with Consol idometer0

aA subsection of USBR E-15 contains directions for computing permeability by
 the falling-head method.


 USCE App. VII (5) pertains to undisturbed soil  samples.


cNot recommended.

                                       3-35

-------
                                     TABLE 3-5

                            PERMEABILITY CONVERSION FACTORS3

Meinzer,
gallons per
cm per s ft per Day ft per Year Darcy day per ft
cm per s 1 2.835 x 103 1.0348 x 106 1.033 x 103 2.12 x 104
ft per day 3.53 x 10"4 1 365 3.64 x 10"1 7.48
ft per year 9.67 x 10"7 2.74 x 10~3 1 9.99 x 10"4 2.05 x 10"2
Darcy 9.68 x 10"4 2.75 1.001 x 103 1 20.50
Meinzer 4.72 x 10'5 1.34X10"1 48.8 4.88 x 10"2 1
gallons per day per ft
in. per hr 7.06 x 10"4 2 729 7.29 x 10"1 14.9

in. per hr
1.42 x 103
0.5
1.37 x 10"3
1.37
6.70 x 10"2
1

aMultiply the unit at the left by the number in the column to get the unit at the top of the column.  All
 units are based on a temperature of 60°F or 15.6°C (from Johnson, 1981).


         3.2.5.8  Shrink/Swell  Behavior; Activity


    Certain clayey  soils have  a high tendency to swell on wetting and shrink
on drying.  Such  behavior correlates with a clay-mineral  property known as
activity.

                                     A = £!
                                     M   c

where  PI  is  plasticity index and  C  is percent clay-size  material (<2 Lim),
or,
                                    A =
                                        C - n
with  n  varying  between  5 and 10 (Mitchell, 1976).  The  activity of clays
varies from 0.1 to  7,  as  shown by Table 3-6.  However,  virtually all of the
upper range is occupied by smectites (smectite is effectively  synonymous with
montmorillonite).   Active clays mean highly expansive,  highly  compressible
soils.  Where such  soil is used in a cover system, there  is  a  potential for
disruption through  cracking on drying.

    Expansive soils  are generally well  known in the areas where  they occur
from construction problems with foundations and highways.  The great prepon-
derance of such soils  classify as CH in the USCS (discussed  below).   Sugges-
tions for dealing with expansive soils  in landfill cover  applications are
given by Lutton,  Regan, and Jones (1979).   Research on  identification of su'ch
soils was reported  by  Snethen, Johnson, and Patrick (1977).  For the highway
engineer, Oglesby (1975,  pp 447, 518) recommends, for clay soils,  compaction
somewhat wet of optimum and to no greater than about 90 percent  of Standard

                                       3-36

-------
                                   TABLE  3-6
                        ACTIVITIES OF VARIOUS MINERALS3
     Mineral                                                         Activityb

 Smectites                                                                1-7
 II lite                                                                0.5-1
 Kaolinite                                                             0.5
 Halloysite  (2H20)                                                     0.5
 Halloysite  (4H20)                                                     0.1
 Attapulgite                                                           0.5-1.2
 Allophane                                                             0.5-1.2
aFrom Mitchell (1976).

Activity, A = Plasticity Index
                   % <2 prn
AASHTO (Standard Proctor) density, in order to avoid postconstruction swelling.

    Standardized tests of shrink/swell behavior of soils are listed in
Table 3-3.
         3.2.5.9 Dispersivity


    Certain clays show a property known as dispersivity.  This is a tendency
to go into colloidal suspension, and thus to erode very readily.   On a micro
scale, clay particles change from a flocculated to a dispersed state.   Nondis-
persive soil in contact with flowing water requires a certain threshold veloc-
ity before it will start to erode.   Dispersive soil, in contrast, requires no
threshold velocity; colloidal particles pass spontaneously into suspension in
still water.

    Dispersive soil is a serious problem in some earthfill dams,  where piping
erosion can lead to failure.  In a cover system dispersivity involves mainly a
threat of soil erosion, either surface erosion or internal erosion where, in a
layered cover, a layer of dispersive fine-grained soil  might be in contact
with a granular, pervious soil.

    The transfer between flocculated and dispersed states is an electrochemi-
cal surface process and is sensitive to the chemistry of both the clay mine-
rals and the pore fluid.   Dispersivity appears to be associated with sodium
saturation of clay-mineral surfaces.   Given such surface saturation, the na-
tural pore fluid of such a soil  will  be sodium-rich.   When this soil is ex-
posed to either pure water or a dilute solution low in dissolved sodium, ion

                                      3-37

-------
exchange, flushing of the adsorbed sodium,  and dispersive erosion tend to
follow.

    Dispersivity is not revealed by common  engineering soil  indices such as
Atterberg Limits.   Clues to dispersive soil may be found locally in the form
of deep gully or tunnel erosion of exposed  soil surfaces.   Several  tests have
been developed, which are simple, inexpensive, and quite reliable.   These are
the pinhole test;  saturation extract analysis; Soil Conservation Service (SCS)
dispersion ("double hydrometer") test; and  crumb test.  Descriptions and dis-
cussions of these tests may be found in Sherard, Dunnigan, and Decker (1976),
Mitchell (1976), papers in Sherard and Decker (1977).   The pinhole test may be
found in USCE (1980 revision; Appendix XIII).   The pinhole test is commonly
regarded as the most reliable single test,  but several authors in Sherard and
Decker (1977) recommend corroboration by more than one test method, particu-
larly in view of the simplicity of the test procedures.   The crumb test, for
example, involves simply dropping a crumb of soil into a beaker of water and
observing its reaction.

    Two techniques have been used successfully to counter the erosive effects
of dispersive soils.  One is treatment with hydrated lime; the other is the
use of graded filters where the threat of internal erosion exists within an
earthfill dam.  Possible dispersive-soil problems in a cover system should be
amenable to treatment by one or both of these techniques.   Lime may have the
side effect of increasing permeability, however.

    The cover designer should be aware of the threat of dispersive behavior
when using bentonite to amend a soil to achieve impermeability.  The high-
swelling Wyoming bentonite that is most desired as a sealant contains sodium-
saturated clay and is subject to the dispersive tendencies mentioned above.
When bentonite is used, the gradation of the material  used with it is very
important.  It is necessary to achieve a filter effect by having sufficient
granular fines to stabilize the bentonite against dispersive erosion.
D'Appolonia (1980) reports on the danger of piping failures where such a pre-
caution is not followed.  According to D'Appolonia (p 415) the use of ben-
tonites treated with certain polymers may also assist in preventing piping
failures.  Since bentonite contains highly active clay minerals, it is also
susceptible to attack by organic solvents or other chemicals that may be pres-
ent in wastes.  Bentonite is further discussed below  in section 3.3.1.2.


         3.2.5.10 Other Soil Properties and Tests


    Other soil properties and tests may be of  interest for specialized pur-
poses.  Soil  information required for the purposes of designing for vegetation
is discussed  in section 4.3 below.  Factors that may  be of interest  include
soil reaction  (pH), cation exchange capacity,  and organic content.  The  reader
is referred to Black (1965) for technical  information on  soil  analysis or
testing  for agricultural purposes.  The discussion above  under permeability
suggests the  relative  complexity of water-related phenomena  in unsaturated
soils.   For a  discussion of capillary phenomena, the  interested reader  is
referred to the discussion of capillarity  in Taylor (1948).  Other  sources

                                      3-38

-------
 (e.g., Snethen, Johnson, and  Patrick,  1977a;  Brady,  1974) explain the  phenome-
 non  known as  soil  suction.  Many of  the  specific behavioral complexities of a
 soil  relate to  its mineralogical composition.  Mineralogical analysis  of fine-
 grained soil  is complicated.  Qualitative and semi quantitative analyses are
 relatively reliable, but quantitative  mineralogical  analysis of clays  achieves
 nowhere near  the precision  of chemical analysis or even of mineralogical anal-
 ysis  of coarser-grained aggregations.  The chief analytical methods are X-ray
 diffraction and differential  thermal analysis; these are explained in  Mitchell
 (1976) and elsewhere.  Mineralogical analyses  should be undertaken by  special-
 ized  laboratories.
    3.2.6 Engineering Characteristics of Soil Types


    Rankings and evaluations of the various USCS Groups have been made for
various purposes.  Table 3-7 shows an evaluation with regard to use in roads
and airfields, prepared by the U. S. Army Engineer Waterways Experiment Sta-
tion.  Table 3-8 shows an evaluation and ranking with regard to earth dams
and associated features, prepared by the U. S. Bureau of Reclamation.
Table 3-9 shows a set of rankings prepared by Lutton, Regan, and Jones (1979)
for categories of engineering behavior that are pertinent to cover systems.
Since these authors were concerned with municipal as well as hazardous waste
disposal sites, several categories appear in Table 3-9 that are not discussed
in this Handbook.

    Table 3-10 summarizes soil properties obtained in more than 1500 soil
tests performed by the Bureau of Reclamation, arranged according to soil clas-
sification groups, including frequently occurring boundary groups (Hilf,
1974a).   Most of the soils were from the western United States; some were from
foreign sources.   The geographical distribution is not believed to have af-
fected the classifications.

    The cover designer considering the use of soils for construction of the
various components of a cover system, as discussed below in Chapter 4, can
refer to these tables for information as to which types of soil are best
suited for which components of the system.   However,  it should be clearly
understood that for design purposes, material properties for the specific site
in question must be used, rather than general properties from these or any
other tables.
3.3 Soil Additives
    Soil additives refer to manufactured commercial products, specially proc-
essed natural materials, or the by-products of a commercial process that, when
added in the proper quantities, will improve the characteristics and perform-
ance of a soil.   Generally, soil additives are employed to improve the soil's
performance in the areas of stability and permeability.  Stabilization in-
volves the process of blending or mixing an additive with a soil to improve or
control the volume, stability, strength, stress-strain characteristics, and/or

                                      3-39

-------
                                                         TABLE 3-7

                           CHARACTERISTICS OF USCS SOIL GROUPS PERTINENT TO ROADS AND AIRFIELDS
(1)
CCA RSI -
CM2OD

SOILS

(2)
CMVH.
ATO
CHAVTLLT
SOILS


SAXC
SOILS

SILTS
curs
IX IS
LESS

SILTS
U. IS
TMN S0
IIGTLT CPCAKIC SOILS
8y^01

IJ)
CV
CP
r
G» i-
t u
i
cc
EU
SP
n !
t
sc
•a.
CL
OL
"
n
en
pt

(
c

t
F
;.
:•



y
\\

f
f



O
•
l|

:





i
i




I;)
-3

0
a



i
a


s

a

-1

Dame
We LI -graded gravel* or gra'rl-Mnd
Poorly graded graveli or gravel-Mud
.m,.™!..^!-^..,!,^™.
cum ,r.,.u. .™™i.™d.o,., .,„,*..
UeJJ -graded e«ndi or gnveJly (and*,
Poorly graded und* or Kravelly


^'—•. ••—'——
norEsnlc *llt» ard very fine sandi, rock
layt, lean clays
l4 .!..,..«, "
fin* *aody or illty 3oU», eLaiCIC «Ut(
cl-yi
Crgiolc cUyi of aedlui to high


Uhen Nnl Subject to
ru'fT)'
ExceUent
Oood to excellent
"°" " ««"«•
Good
c«*
"^

'"' " '"^
Fair
Poor to fair



Poor
Poor to fair
Poor ,0 „.„ poo.


r:f£ j«*:;
U..U...
Good
Good
fair
Pair
fair to good
Fair
Fair to good
Poor to fair
Poor



Not Stable
Not tultabl*



1 	 ' '
Valua •* Knae
Whi-n Not Uubject
Good
Fair to good
Fair to good
Poor to not tultablt
Poor to not lultable
Poor
Poor ,0 .0, .„„.»„
or
•* .ultable
Hot iiiltable
Not aul table
ot aulta if
Not .ult.bl.
Not aultablr
Not lultable

Not lultable
Futrntl*!
Pruit
Action
(1°)
Don* to very
BlUht
X'.0""
ntdiua
Slight to
Slight to
BatdlU*
NOM to very
•light
»on* to very
alight
Slight to
kigtt
high
Slight to
™ry high
blgA
high
Medlun to
very hlgb
Itedlu,
*«.
Slight
• nd
m> "°
"--
Alaoit noD>
Very alight
Slight
—
Alaoit none
Aliwit nOD*
Very .light
Slight to KdluB


ffcdl-
IktUjo to high
Kith
High
High
--»
Ch.r.c7,~.tu,
EcctUent
Excellalit
•"• —

lapervlou*
i (.tlluit
r.»u.«
Fair to poor



Praetlc»lly
Unpervlou*
Poor
F«lr to poor
Practlc»Uy

Fair to i>oor
CooMctlOD Equlpocnt
Cra»lrr type tractor, rubber-tired
roller, iteel-ubteltd roller
Crs^ler-type tractor, rubber-tired
^rr-^^TL-far^

J*uti>*r-t!iTd roller, mherpffoat
roller
Cnialer-lype tractor, rubber-tired
roller
Cnvler-typ* tractor, rubber-tlnd
Rubber-tired roller, *heep*root
roller, dote coatrel of
•olitur*
roller
»»„.„« „,,.„. .*.„.,.,.
.s^r.'salr=..r-.
ButVr-tlnd roller, iheepifoot
roller
roller
Sbuptfoot roller, rubber-tired
roller
Sb*r.p«foot roller, rubber-tired
roller
S^,p.f^t ^UT. n-bber-t^d
Coojactlon not practical
Uolt Dry
Weight
ID per cu ft
(1")
125-11-0
HO-1UO
.,-«
115-135
130-HS
110-130
-105-1J5
1M-135
100-130
100-1 JJ
90-130
90-130
90-105
*,-,«,
90.U,
oO-LlO

TJ^P j_»I >.l4n \alx.,..
CW
(If)
hO -60
30-60
tO -60
20-30
«~
20 -AO
ioJ.
15-W
10-20
,-»
15 Or
leu
i.,.r
i««
10 or
15 or


h
lb p*r cu ID.
(16)
300-500
—
300 -joo
*»-•»
».„
200 -WO
iil-tOO
1SO-WO
100-3X
JOO-3M
100-a?00
50-150
»-iA>
M,»
50-1W
25-100

OO
I
   From  "The  Unified  Soil  Classification System"  (Geotechnical Laboratory,  1982)

-------
                              TABLE  3-8

       ENGINEERING USE CHART  FOR USCS SOIL GROUPS, WITH  EMPHASIS
                 ON  EARTH DAMS AND RELATED FEATURES
TYPICAL NAMES
OF SOIL GROUPS
«LL GRADED GRAVELS.GWVEL
NO FINES
LITTLE OR HO FINES


CL-.E. GRAVELS, POOSL-
CLAt.LMJttS
WE.L GRADED SANDS
GRAVELLY SAND', L.T'LE
PQORL" GRADED SANDS
GRAVELL' SANDS UTTLE
OF) NO FINES
SiLTY S.N05 PQQRL.

C.A.EV SANDS POOBLY
GflADED SAND CLAY
inTY oft CLdttEi FINE SANDS
WEDIUM PLASTICITY
GRAVE.L' CLAYS SUNDY CLAYS

S LT CLAiS OF LO*
PLAST,CITY
NORGANIC SIL'S MICACEOUS
Of DIATOMACEOU5 FINE
aasnc SILTS
INORGANIC CLAYS CF HIGH

TOH.GHPLASTIC.TY
PEAT 0 I R
OftGlN.C SO.LS
GROUP
SYMBOLS


OP




„
SP


sc


-
.L
„

OH
„

PERMEA-
BILITY
COMPACTED


vEftr PtBuiOUS




PERVIOUS



roiM"E»v,OuS
,,P£,,,0.S




ssr,
SEMIPEP.VIOUS
TO iMPERVIOLyS
IMPEHU'OUS
,.,„,„„
—
IMPORTANT
SHEARING
STRENGTH
WHEN
COMPACTED
AND
SATURATED


&000




E-C^E,,




GOOD TO FliR




.,0,
FSifl TO POOR
POOB
POO,


PROPERTIES
COMPRESS-
IBILITY
COMPACTED
AND
SATURATED


..^E




,^0..,=




,.




.E.™
.,0,
,,0.
«S,



WORKABILITY
AS A
CONSTRUCTION
-MATERIAL


™.
„.=


EXCE.t ENT


„„
GOOD




p.,.
PO,,
.00,
,0..


GROUP
STUBOLS

0>

s.
»
»

0,
.,
c-
0,
p,
REL.TWE DES,»AB,L,TY FOR V.RIOUS USES .

HOMO
GENEOUS
EMBANK
MENT


—
*

—
—
•


'
>
•
'
'
,0


CORE


—

-
—
—
•


•
•
•
9
'
,0


SHELL
'
2




WWELuY
RArtLL.
—






—
—





EROSION
RESISTANC

'
'
'

BPMLl.
SmvELL.




—
~
,


—
COMPACTt
EARTH
LINING
_
—
•

—
—
i

shi
CBITICAl
—
CHANGE
CRITICAL


—
FOUNDATIONS
SEEPAGE
1 MPORTANT


—

>
—
—


•
•
'
•
•
0
__
SEEPAGE
NOT
IMPOflTAN
'
'
•
6
•




•
°
"
i;
»
..
—
ROADWAYS
FILLS
FROST
HEAVE
NOT
POSSIBLE

>
•
>
!
«
•
•0
'
"
"
'
I.
—
FfiOST
HEAVE
POSSIBLE

'
»
-
'
;
*

«
»
•
,.
—

SURFACING

	

•
'

,
—
—
_
___
—
Earth Manual  (U.S.  Bureau of Reclamation,  1974b)
                                 3-41

-------
                                                               TABLE  3-9
          RANKING  OF  UNIFIED-SYSTEM (USCS) SOIL GROUPS WITH REGARD  TO  COVER-RELATED  ENGINEERING  BEHAVIOR*
CO
 I
-p.
                       Best group appears  first, worst group appears last;  groups  separated  by commas have equal rank.
                                                     GW, GP, SW, SP;  SM;   GM;   SC;   GC;  CH;  CL;  MH;  ML;  OL;  OH;  Pt
                                                     GW, GP;  SW, SP;  GM;  SM;   ML;   OL;   GC;  SC;  CL;  MH;  CH
                                                     GW, GP;  SW, SP;  GM;  SM;   GC;   SC;   ML, OL;  CL;  MH;  CH
                                                     CH;  CL;  MH;  ML;  GC;  SC;  GM;   SM;  SW;  GW;  SP;  GP
                                                     GP;  SP;  GW;  SW;  SM;  GM;  SC;   GC;  ML;  MH;  CL;  CH
                                                     CH;  CL;  ML;  GC;  SC;  SM;  SP,  GM;   SW;  GP;  GW
                                                     GW;  GP;  SW;  GM, SP;  SM;   SC;  GC;   ML;  CL;  CH
                                                     CH;  CL;  ML;  GC;  SC;  SM;  SP,  GM;   SW;  GP;  GW
                                                     GW, GP;  SW, SP;  GC;  GM;   Pt;   SM;   SC;  OH;  CH;  MH;  OL;  CL;  ML
                                                     GW, GP; SW, SP;  GM;   SM;   GC;   SC;  ML, OL; CL;  MH;  CH
                                                                            SM;   GC;   SC;   ML, OL;  CL;
Trafficability,  GO/NO-GO:
Trafficability.  Stickiness:
Trafficability,  Slipperiness:
Impede Water Percolation:
Assist Water Percolation:
Impede Gas Migration:
Assist Gas Migration:
Fire Resistance:
Water-erosion Resistance:
Wind-erosion Resistance:
Dust Control:
Crack Resistance:
Reduce Freeze  Action:   Fast  Freeze:
Reduce Freeze  Action:   Saturation:
Side Slope  -   Seepage:
Side Slope  -  Drainage:
Discourage Burrowing:
Impede Vector  Emergence:
Support Vegetation:
Future Use, Natural:
Future Use, Foundation:
Side Slope Stability:
Discourage Birds:
GW, GP;   SW,  SP;   GM;
                                                   MH;  CH
                                                            CH
GW, GP,  SW,  SP;   SM;   GM;  SC;  GC;  ML;  OL;  CL;  OH, MH;
CH;  CL;   ML;  GC;   SC;  SM;  GM, SP;  SW;  GP;  GW
GW, GP;   SW,  SP;   CH;  GM;  SM;  SC;  GC;  CL, OL;  MH;  ML
CH;  CL;   MH;  ML;   GC;  SC;  GM;  SM;  SW;  GW;  SP;  GP
GP;  SP;   GW;  SW;   SM;  GM;  SC;  GC;  ML;  MH;  CL;  CH
GW, GP;   SW,  SP;   GM;  SM;  GC;  SC;  ML, OL;  CL;  MH;  CH
CH;  MH;   CL;  SC;   GC;  ML, OL;  SM;  GM;  SP, SW;  GP, GW
SC;  SM;   Pt,  ML;   MH, OL;  GC;  GM;  CL;  CH, OH;  SP, SW;  GP,  GW
SC;  SM;   Pt,  ML;   MH, OL;  GC;  GM;  CL;  CH, OH;  SP, SW;  GP,  GW
GW, GP,  SW,  SP;   SM;   GM;  SC;  GC;  CH;  CL;  MH;  ML;  OL;  OH;  Pt
"determine on  basis on laboratory testing"
"all soils are suitable"
                    After Lutton, Regan, and Jones  (1979); see text.

-------
                                                           TABLE  3-10
                                                  AVERAGE  PROPERTIES  OF SOILS3
Proctor Compaction
Soil
Classifi-
cation
Group
GW
GP
GM
GC
SW
SP
SM
SM-SC
OJ
i SC
U) ML
ML-CL
CL
OL
MH
CH
OH
Maximum
Dry Density
In Pounds
Per Cubic
Foot
>119
>110
>114
>115
11915
110+2
114+1
119+1
11511
10311
10912
108+1
(*)
8214
94+2
(*)
Optimum
Water
Content,
Percent
<13.3
<12.4
<14.5
<14.7
13.312.5
12.411.0
14.5+0.4
12.8+0.5
14.710.4
19.210.7
16.810.7
17.3+0.3
(*)
36.313.2
25.511.2
(*)
Void
Ratio,
e
o
(*)
(*)
(*)
(*)
0.371*
0.50+0.03
0.48+0.02
0.41+0.02
0.4810.01
0.6310.02
0.5410.03
0.5610.01
(*)
1.1510.12
0.80+0.04
(*)
Permeability,
k,
Feet Per Year
27,000+
13,000
64,0001
34,000
>0.3
>0.3
(*)
<15.0
7.514.8
0.810.6
0.3+0.2
0.59+0.23
0.1310.07
0.0810.03
(*)
0.1610.10
0.0510.05
(*)
Compressibility
@ 20 p.s.i. ,
Percent
<1.4
<0.8
<1.2
<1.2
1.41*
0.810.3
1.210.1
1.410.3
1.2+0.2
1.510.2
1.010.2
1.410.2
(*)
2.011.2
2.611.3
(*)
@ 50 p.s.i.,
Percent
(*)
(*)
<3.0
<2.4
(*)
(*)
3.0+0.4
2.9+1.0
2.410.5
2.610.3
2.210.0
2.610.4
(*)
3.8+0.8
3.9+1.5
(*)
Shearing
C
o
p.s.i.
(*)
(*)
(*)
(*)
5.7+0.6
3.3+0.9
7.410.9
7.313.1
10.9+2.2
9.7+1.5
9.2+2.4
12.6+1.5
(*)
10.5+4.3
14.914.9
(*)
Strength
Csat
p.s.i.
(*)
(*)
(*)
(*)
(*)
(*)
2.911.0
2.110.8
1.6+0.9
1.31*
3.21*
1.910.3
(*)
2.911.3
1.610.86
(*)
tan 0
>0.79
>0.74
>0.67
>0.60
0.79+0.02
0.7410.02
0.6710.02
0.6610.07
0.6010.07
0.62+0.04
0.62±0.06
0.54+0.04
(*)
0.47+0.05
0.35+0.09
(*)
 Based on USER experience; see text.   From Hi If (1974a).
The 1 entry indicates 90 percent confidence limits of the average value.
*  Denotes insufficient data,  > is greater than,   < is less than.
Note:  One foot per year equals approximately 10"   centimeters per second (precisely, 9.665 x 10   cm/sec).

-------
durability of that soil.   An additive modifies the permeability of a soil  by
altering the soil's pore size and/or pore size distribution or by creating a
cemented structure within the soil.

    A requirement to use a soil additive is more likely where a multilayered
cover system is constructed.  The multilayered cover concept is discussed  in
Chapter 4.   Elements of a cover system that might employ soil additives for
these purposes are the foundation layer and the barrier layer.   A site's in-
ability to provide a stable surface  on which to construct an appropriate cover
may in some cases be overcome through the utilization of the proper soil addi-
tive.   Likewise some materials' applicability as a barrier to percolating
water may be enhanced with the use of an appropriate additive.


    3.3.1 Common Soil Additives and  Their Applications


    The most commonly used soil additives are bentonite, lime,  port!and ce-
ment,  fly ash, and bituminous materials.  In the selection of one or more  of
these additives, certain factors must be considered which will  ultimately
determine their effectiveness.   These factors are:   purpose for improving  the
soil,  soil  type, degree of soil quality improvement desired, and environmental
conditions (geochemical nature of site, weather, etc.).   The chemical nature
of the wastes should also be considered in selecting a soil additive.

    With the exception of bentonite, each of the above-mentioned soil additives
has been used for both stabilization and impermeabilization.  Bentonite serves
only to decrease a soil's permeability.


         3.3.1.1 Soil Stabilization
    For stabilization Figure 3-15 and Table 3-11 provide initial guidance in
selecting a bituminous material, Portland cement, lime, or lime/cement/fly-ash
mixture.  Enter Figure 3-15 with the percentages of gravel, sand, and fines;
determine the area'(!A, 2C, 3, etc.) where the intersection of these three
percentages lies.   Given this area number, refer to Table 3-11 for guidance
for the initial selection of the best-suited additive.   Note the restrictions
in Table 3-11 regarding Atterberg limits and gradation.  For example, a soil
containing 60 percent gravel, 30 percent sand, and 10 percent fines falls
within area 2B of Figure 3-15.  Table 3-11 indicates that bituminous mate-
rials, lime, and lime/cement/fly-ash could be considered.  Portland cement is
eliminated, as only 40 percent of the material passes the No. 4 sieve.   If
soil tests indicate a PI of 17, then lime or a combination of lime, cement,
and fly ash will be the better additive for stabilization.  However, this is
initial guidance only, and the best additive can only be determined by labora-
tory studies such as those outlined in "Soil Stabilization for Pavements"
(Departments of the Army, Air Force, and Navy, 1982).
                                      3-44

-------
                    FIGURE  3-15

CHART  FOR SELECTING SOIL-STABILIZING  ADDITIVES
          (TO BE  USED WITH TABLE 3-10)
                    LEGEND

          — •— BOUNDARIES BETWEEN MAJOR
               SOIL GROUPS

           •—— BOUNDARIES WITHIN A MAJOR
               SOIL GROUP
             30      40      50     6O      70

                   PERCENT BY WEIGHT, FINES

                 (MATERIAL PASSING NO. 200 SIEVE!
                        3-45

-------
 1A
 IB
 1C
 2A
 2B
 2C
                                                   TABLE 3-11

                                   GUIDE FOR SELECTING A STABILIZING ADDITIVE

Area

Soils
Class.

Type of
Stabilizing
Additive Recommended

Restriction on LL
and PI of Soil
Restriction
on Percent
Passing
No. 200 Sieve

Remarks
SW or SP
SW-SM or
SP-SM or
SW-SC or
SP-SC

SM or SC
or SM-SC
GW or GP
(1) Bituminous
(2) Portland Cement
(3) Lime-Cement-Fly Ash

(1) Bituminous
(2) Portland Cement
(3) Lime
(4) Lime-Cement-Fly Ash

(1) Bituminous

(2) Portland Cement
(3) Lime
(4) Lime-Cement-Fly Ash

(1) Bituminous

(2) Portland Cement
                  (3)  Lime-Cement-Fly Ash    PI  not  to  exceed  25
PI not to exceed 25

PI not to exceed 10
PI not to exceed 30
PI not less than 12
PI not to exceed 25

PI not to exceed 10
                                            PI  not  less  than  12
                                            PI  not  to  exceed  25
Not to exceed
30* by weight
GW-GM or
GP-GM or
GW-GC or
GP-GC
GM or GC
or GM-GC
(1) Bituminous
(2) Portland Cement
(3) Lime
(4) Lime-Cement-Fly Ash

(1) Bituminous

(2) Portland Cement
                  (3) Lime
                  (4) Lime-Cement-Fly Ash
PI not to exceed 10
PI not to exceed 30
PI not less than 12
PI not to exceed 25

PI not to exceed 10

         b
                                     PI not less than 12
                                     PI not to exceed 25
Not to exceed
30% by weight
                                       Material should not be
                                       uniform-graded.
                                       Material should contain at
                                       least 45% by weight of
                                       material passing No.  4
                                       sieve
                 Well-graded material only
                 Material should contain at
                 least 45% by weight of
                 material passing No. 4
                 sieve
Well-graded material only

Material should contain at
least 45% by weight of
material passing No. 4
sieve
3 CH or CL
or MH or
ML or OH
or OL or
ML-CL

(1) Portland Cement




(2) Lime
LL less than 40 and
PI less than 20



PI not less than 12
Organic and strongly acid
soils falling within this
area are not susceptible
to stabilization by ordi-
nary means

Restriction on liquid limit (LL) and plasticity index (PI)  is  in  accordance with Method 103 in MIL-STD-621A.

bpl < 20 + 50 - percent passing


Source:   "Soil Stabilization for Pavements" (Departments of  the Army,  Air Force,  and Navy,  1982).
                                                  3-46

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         3.3.1.2 Permeability Reduction


    Bentonite, portland cement, lime, fly ash, and bituminous materials have
all been used in modifying the permeability of soils.  Cement, fly ash, lime,
and combinations of them reduce the permeability of a granular soil through
cementation at interparticle contacts and by increasing the percent fines in
the material.  The disadvantage of these additives is that a relatively rigid
layer is formed, which is susceptible to damage from settlement or heave.
Therefore, a stable base must be provided to insure the integrity of a hydrau-
lic barrier constructed using a cement-, fly-ash-, or lime-modified soil.
Although the various types of bituminous additives provide a greater degree of
flexibility, soils modified with them are still vulnerable to the effects of
differential settlement.   Also, the use of bituminous materials is normally
restricted to coarse-grained soils or soils that pulverize easily.

    The addition of lime to a clayey soil typically increases that soil's
permeability.

    Bentonite is a natural material rich in montmorillonite-type clay.   Montmo-
rillonite is distinguished from other clay minerals by its extreme fineness,
high water absorbency, and swelling characteristics upon coming into contact
with water.   This swelling characteristic enables a soil-bentonite layer or
bentonite membrane to demonstrate a "self healing" action.  By this it is meant
that some of the cracks that form in a soil-bentonite or bentonite-only mem-
brane (due to installation practices, subsidence, or drying) will close upon
coming into contact with infiltrating water.   In this respect, bentonite
possesses a distinct advantage over relatively stiffer materials such as soil
cement and asphalt concrete.   However, bentonite is not without problems.   The
performance of bentonite is greatly affected by the quality and type of ben-
tonite.   Some deposits have been found to contain sand, silt, and other clays.
Generally, a Wyoming type bentonite has been found to be satisfactory over the
years from the standpoint of impurities.   Also bentonite has experienced prob-
lems with piping and diffusion through sands and gravels (with large pore chan-
nels).   Studies have shown that sodium bentonite is significantly affected if
placed in an environment rich in calcium ions (CRREL, 1978; also see discus-
sion under "dispersivity," sec.  3.2.4.9 above).   Calcium-sodium ion exchange
can have a pronounced effect on bentonite's ability to act as a sealant.   Or-
ganic solvents and other nonpolar chemicals can also have a harmful effect on
bentonite.
    3.3.2 Soils Suitable for Stabilization/Modification
    The type of soil to be modified will usually dictate the feasibility of
using certain soil additives.  Generally, the ease with which an additive can
be blended into a soil is a function of the soil type.   For many additives
(particularly bitumen and cement) the degree to which they can be uniformly
distributed in the soil will be critical to their performance.   As a rule
of thumb, as the PI and percent fines in a soil increase, the pulverization
of that material becomes more difficult.  As pulverization becomes more

                                      3-47

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difficult,  the harder it becomes to obtain a uniform distribution of the addi-
tive.   In general,  bituminous materials and portland cement work best in
coarse-grained soils that pulverize easily, while lime is usually used on
fine-grained soils, as it lowers the PI of the soils to which it is added.

    The detailed guidance in Table 3-11 is in accord with these rules of thumb.


    3.3.3 Soil Blending


    Although not involving a soil additive as such,  the process of blending
one type of soil with another does touch on the purposes of using soil addi-
tives.   By combining soils with different gradations it may be possible to
obtain a material meeting the desired specifications for stability and/or
impermeability.   Through the addition of coarse- and/or fine-grained soil, a
well-graded material having improved strength and drainage characteristics may
sometimes be obtained.


3.4 Nonsoil Materials


    3.4.1 General


    "Nonsoil materials" as used here, refer to any materials or supplies
(e.g.,  pipes), other than a natural soil, that may be used in the design and
construction of a cover system.  These include several materials mentioned
above as soil additives.  Others discussed below include materials that serve
to form an impermeable component of the cover system; bulk materials poten-
tially useful in construction, originating as industrial wastes or residues;
materials and supplies that serve special functions, such as drainage pipes
and tiles;  and permeable synthetic fabrics known as  "geotextiles" which serve
a variety of engineering functions including strengthening, stabilizing, and
separating soils.


    3.4.2 Impermeable Materials


    Impermeable materials restrict or direct the movement of water and/or gas
within a cover system.  The most common types of nonsoil impermeable materials
are bituminous materials such as asphalts and tars;  polymeric membranes; and
concrete and cement.


         3.4.2.1 Asphalt


    The most common forms for asphalt encountered as a barrier are:   (1) hot-
sprayed asphalt/tar membranes; (2) asphalt emulsions; (3) reinforced, sprayed

                                      3-48

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asphalt membranes; (4) asphaltic concrete; and (5) prefabricated asphalt lin-
ing.   A hot-sprayed asphalt membrane consists of a relatively tough,  high-
viscosity, high-softening-point asphalt or tar.   Usually, a hot-sprayed mem-
brane does not contain any filler or aggregate.   The asphalt or tar utilized
for this purpose must be ductile enough to conform to the irregularities of
the base material and to resist cracking during its service lifetime, yet
strong enough to withstand the stresses imposed upon it during the construc-
tion of the overlying cover layers.

    An asphalt emulsion consists of three basic components:  asphalt, an emul-
sifying agent, and water.   The emulsifying agent disperses the asphalt cement
in water, creating a mixture that is stable enough for pumping, prolonged
storage, and mixing.  Ideally, the emulsion should break down quickly upon
coming into contact with the surface to be treated, and shouUJ retain all the
adhesion, durability, and water-resistance of the asphalt cement from which it
was formulated.   Generally, asphalt emulsions are classified according to
behavior in an electrical  field and according to rapidity with which  the emul-
sion will revert to asphalt cement (coalesce).  Asphalt emulsions are clas-
sified as anionic, cationic, or nonionic, depending upon which direction the
positively charged particles in the emulsion move when an electric current
is passed through it.  Emulsions are further grouped as slow-setting  (SS),
medium-setting (MS), or rapid-setting (RS).  The prefix "C" is added  to the
asphalt emulsion grade if the mixture is cationic.  For example, an RS-2
emulsion is either anionic or nonionic, and a CRS-2 is cationic.

    Where tensile-strength requirements exceed the strength of a sprayed-
asphalt membrane (such as on steep slopes), a mat of reinforcing material is
added to the membrane.  This reinforcement (normally a geotextile) is placed
on the ground, and the asphalt is sprayed over it.  Geotextiles used  for this
reinforcement have included fiberglass mats, polypropylene, and polyester.
The selection of the geotextile should be based on the facts that the geotex-
tile could be exposed directly to the environment and that it must possess
sufficient openings to allow asphalt penetration.  Delaminations in reinforced
sprayed-asphalt membranes have occurred in the past as a result of the rein-
forcing material's being attacked by microorganisms or by the geochemical
nature of the soil, as well as of inadequate penetration of the asphalt into
the reinforcement.

    Asphaltic concrete is a mixture of hot asphalt cement and well-graded,
high-quality aggregate, compacted to form a uniform, dense mass.  The type of
asphaltic concrete that would be used as an impermeable barrier layer is simi-
lar to that used for highway surface courses, with the exception of having a
higher percentage of mineral filler and asphalt cement.

    There are basically two types of prefabricated asphalt lining material.
One is manufactured in the form of a panel or board, while the other  is pro-
duced in rolls,  much like roofing.  The prefabricated asphalt panel is stronger
and more durable than the rolled lining, but the rolled lining is more flexible
and less expensive.  Unlike the other two types of asphalt barriers,  the seam-
ing process for prefabricated asphalt panels must be accomplished by  hand.
Table 3-12 compares prefabricated asphalt lining with the other two types of
asphalt barriers.

                                      3-49

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                                        TABLE  3-12

ADVANTAGES/DISADVANTAGES  OF  VARIOUS FORMS  OF  ASPHALT  CONSTRUCTION
            Material
                                 Advantages
                                   Disadvantages
          Hot-Sprayed
          Membranes:
          b.  Tars
         Asphalt
         Emulsion
Provide  tight  imper-
vious barriers.
          a.  Asphalt     b.   Good availability.


                         c.   Can be mechanically
                             installed.
                         d.   Does  not have exten-
                             sive  equipment needs.


                         e.   Can penetrate tight
                             surfaces to plug
                             voids and open
                             surfaces.

                         f.   Very  dense mixtures
                             resist plant intru-
                             sion  better.
                         a-f.   Same as for
                               asphalt.

                         g.   Tars mix well with
                             wet aggregate.
a.   Does not  have exten-
    sive equipment needs.

b.   Does not  require a
    petroleum to make it
    liquid.
c.   Can be applied in
    most cases without
    the use of addi-
    tional heat.
d.   Has the ability to coat  d.
    damp aggregate surfaces.

e.   There is  little or no    e.
    hydrocarbon emission.
f.   Can penetrate tight      f.
    surfaces.
                            a.   Requires  up to 3 passes to in-
                                sure integrity.

                            b.   Special heating and storage
                                equipment required.

                            c.   More vulnerable to damage from
                                plants  and animals than
                                asphalt concrete.

                            d.   The subgrade soil must be
                                carefully prepared to remove
                                sharp or  large objects.

                            e.   Susceptible to cracking during
                                cold-weather installation.
                        f.   Protective cover is essential.

                        g.   Cannot support much traffic
                            (human or vehicular).

                        h.   Poor  resistance to oils and
                            organic solvents.

                        a-h.   Same as for asphalt.


                        i.   Tars  are more susceptible to
                            weathering effects than
                            asphalts.
                        j.   Some  tars require high
                            temperatures.
                        k.   During application, vapors may
                            burn  personnel that come into
                            contact with them.

                        a.   Extensive curing times may be
                            required.
                        b.   Subgrade soil requires careful
                            preparation.


                        c.   Cannot support much traffic.
                                                         More vulnerable to plant and
                                                         animal attack than asphalt
                                                         concrete.

                                                         Protective cover is essential.
                                                         Poor  resistance to oils and
                                                         organic solvents.
                                                                           (continued)
                                               3-50

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                       TABLE  3-12  (continued)
   Material
                       Advantages
                                        Disadvantages
Reinforced,
Sprayed
Asphalt
Membranes
Asphalt
Concrete
Prefabricated
Asphalt
Lining
a.   Greater fatigue
    (tensile) strength
    than unreinforced
    asphalt membranes.

b.   May be placed on
    steeper slopes than
    nonrei nforced
    membrane.

c.   Greater tear resist-
    ance than
    nonreinforced.
d.   Equipment needs are
    not too extensive.
                d.
    Provides a very sta-
    ble working surface
    from which to con-
    struct the rest of
    the cover.

    Better resistance to
    attack from plant
    roots and burrowing
    animals than sprayed
    membranes.

    Will support traffic
    better than sprayed
    membranes.
    Can be installed
    where it is  diffi-
    cult to operate
    machinery (asphalt
    distributors,  pavers,
    rollers, etc.)

    Does not require the
    degree of subgrade
    compaction as  the
    other types  of
    asphalt materials.
    Can be manufactured
    under greater  quali-
    ty control than
    field constructed
    materials.
    Equipment needs are
    minimal.
                e.   Resist tearing.
a.  Careful selection of fabric is
    required.
                                             b.   Cost is  greater  than  nonrein-
                                                 forced membrane.
c.  Delamination may occur from
    microorganisms or soil
    chemistry.

d.  Susceptible to cracking in
    cold weather installation.

e.  Protective cover is essential.

f.  More vulnerable to plant and
    animal attack than asphalt
    concrete.

g.  Only as good as the asphalt or
    asphalt emulsion sprayed on
    it.

a.  Requires specialized heating,
    storing, and construction
    equipment.
                                             b.   Requires  more  highly  skilled
                                                 personnel  than sprayed
                                                 membranes.
c.   Relatively stiffer material
    with regard to subsidence.

d.   Poor resistance to oils and
    organic solvents.

e.   Vulnerable to cracking during
    cold weather installation.

a.   Expensive.
                                                 Susceptible  to cracking during
                                                 cold weather installation.
                                             c.   Panels  are  very  heavy.
d.   Cannot withstand rapid changes
    in subgrade elevation.

e.   Seams are not usually as
    strong as panel  material.

f.   The fabric must  be chosen
    carefully as microorganisms
    may attack them.
                                       3-51

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    For additional  information on asphalt consult "Asphalt in Hydraulics"
(Asphalt Institute,  1976).


         3.4.2.2 Synthetic Membranes ("Geomembranes")


    The use of synthetic membranes in the waste-disposal  field now spans over
two decades.   Basically, these membranes fall  within one  of three categories:
elastomers (rubbers), thermoplastics (plastics),  and combinations of elastomers
and thermoplastics.   Butyl rubber, ethylene propylene  rubber (ethylene pro-
pylene diene monomer, EPDM), and neoprene are  the most commonly used rubbers,
while polyethylene (PE), polyvinyl chloride (PVC), and chlorinated polyethylene
(CPE) are commonly used plastics.  Chlorosulfonated polyethylene (CSPE), a
common commercial variety of which is Hypalon,* and DuPont's 3110 (no longer
marketed) exhibit qualities found in both the  rubbers  and the plastics.   Poly-
ethylene is available as low-density (LDPE), high-density (HOPE), and linear
low-density (LLDPE) polyethylenes.  Table 3-13 presents these various types of
polymeric membranes, their advantages and disadvantages,  and general informa-
tion concerning their engineering and physical characteristics.

    When considering the use of a polymeric membrane to fulfill  the functions
of the hydraulic barrier, one must first explore the general advantages and
disadvantages involved with choosing this type of barrier over asphalt, soil
cement, etc.   Generally, the advantages include:   (1)  a variety of compounds
are available; (2) sheeting is produced in a factory environment; (3) poly-
meric membranes are flexible; and (4) they are relatively simple to install.

    The disadvantages generally associated with polymeric membranes include:
(1) the chemical resistance of the polymeric membrane must be obtained for
each job; (2) seaming systems are material-dependent and are usually con-
sidered the weak link in a membrane; and (3) many polymeric membranes are vul-
nerable to attack from biotic, mechanical, and environmental sources.  Attack
by biotic agents may be controlled by adding biocides.  Pinholes have been a
problem with some membranes in the past, but recent improvements in membrane
manufacture have markedly reduced the problem.

    The hydraulic barrier in most cases may be underlain by other layers
(e.g., gas collection and foundation), isolating  it from heavy concentrations
of the hazardous chemicals.  However, site conditions allowing a contractor to
place a membrane directly on a contaminated soil  are within the realm of
possibility.  Even  if not directly in contact with a solid contaminant, a
polymeric membrane may be affected by the chemical composition of any gases
intercepted in a gas-collection  layer located beneath the liner.  With these
points in mind, consider the specific advantages  and disadvantages  listed
above.  Polymeric membranes are  available in a wide variety of compounds
suitable  for coming  in contact with various chemicals.  However, no one com-
pound is  resistant  to the entire  spectrum of chemicals that might be encoun-
tered at  an uncontrolled  hazardous waste site.  Also, it  is highly  unlikely
that any  one type of hazardous chemical will be encountered by itself.

*  Registered trademark  of  E.I.  DuPont de Nemours & Co.,  Inc.

                                      3-52

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                                          TABLE  3-13
                          COMMONLY USED  POLYMERIC  MEMBRANES
Polymeric
Membrane
Butyl Rubber












EPDM














HOPE
Hinh
i gn
Density
Polyethylene























CPE


















a.


b.


c.




d.

a.


b.


c.






d.

a.




b.




c.




d.





e.




a.

b.





c.


d.

e.


f.

Advantages
Longest service a.
history

Good b.
availability

Good heat c.
resistance.



Low vapor
transmissivity
Good weathering a.
characteristics

Good ozone b.
resistance

Resists attack c.
by dilute aque-
ous acids and
alkalies, phos-
phate esters,
ketones, alco-
hols, and glycols
Good heat
resistance
Good ozone a.
resi stance



Resistant over a b.
wide range of
chemicals


Available in c.
greater thick-
nesses than
other polymeric
membranes
Thicker ( 60 d.
mills) membranes
are more resist-
ant to mechani-
cal , plant, and
animal damage
Large sheet
widths reduce
the number of
seams per given
area
Good ozone a.
resistance
Can be laminated b.
with other
plastics (such
as PVC or PE)


Good resistance c.
to burning

Good UV
resistance
Good resistance
to soil micro-
organisms
Good hydrocarbon
resistance
Field Usable Typical Typical Available
Seaming Temperature Widths Lengths Thickness Reinforced
Disadvantages Method Ranges (°F) (ft) (ft) (mils) Available?
Poor resistance a. Gum tape -50 to 200 20-35 250-500 20 to 125 Yes
to ozone and
abrasion
Resistance to b. Vulcanization
oils and solvents
is not good
May be difficult c. Contact adhesives
to achieve a good
quality seam in
cold or wet
weather


Poor oil and a. Gum tape -50 to 200 Up to 45 100 20 to 60 Yes
hydrocarbon
resistance
More difficult to b. Vulcanization
vulcanize than
butyl
c. Contact
adhesives







Greater degree of a. Heat welding to 140 10 to 34 200-1000 20 to 140 No
expansion than
most polymencs
may increase
stresses at seams
Seaming in hot
environment can
be difficult due
to undulation of
sheeting
Susceptible to
environmental
stress cracking
(surface cracks)

Relatively stiff-
er material than
other polymeric
membranes







Poor resistance a. Heat welding to 158 to 100 200 10 to 90 Yes
to solvents
Problem concerning b. Contact
delamination be- adhesives
tween pi ies of
this film and
nylon reinforcing
fabrics
Solvent seams are c. Solvent
not as good as
heat welded seams
d. Gum tapes






                                                                                        (continued)
aThis information was compiled from Kays (1977), Pertusa (1980), Shultz and Mlklas (1982), and T.R. 113 (1979)
                                              3-53

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TABLE 3-13 (continued)
Polymeric
Membrane
PVC

















Hypalon


















Neoprene
{Chloroprene
rubber)









Advantages
a. Low initial cost a.



b. Good acid b.
resistance


resistance
e. Relatively easy e.
to field seatn


9-


h.

a. Good resistance a.
to ozone, UV,
and abrasion



b. Good puncture b.
resistance
c. Good abrasion c.
resistance


d. Not adversely d.
affected by
soil chemicals
or micro-
organi sms
e. Good availability
f. Mold resistant
a. Good resistance a.
to oils, grease,
gasoline, acids,
and alkalies
b. Good resistance b.
to abrasion,
ozone, and UV
rays
c. Stronger joints c.
than Butyl and
EDPH are
attainable
Field Usable Typical
Seaming Temperature Widths
Disadvantages Method Ranges (°F} (ft)
Stiffens with age a. Solvent 15 to 160 6
because plasti-
cizer leaves the
compound
Decrease in tear
resistance wi th
age
to ozone
to UV
Susceptible to
attack by soil
microorganisms
to oils
Difficult to bond
to foreign sur-
etc.)
Poor puncture
resistance
Surface atjing can a. Solvent to ISO S
occur if left in
sun making field
seaming di f f icul t
if surfacr core
i s not renoved
Low tensile b. Heat welding
strength
Shrinkage can be c. Contact
a problem in un- ad he s we s
rei nforced
nenbrane
Will not with-
stand exposure to
heavy concentra-
tions of certain
01 Is and sol vents


More expensive a. Contact -10 to 200 20
than other natu- adhesive
ral and synthetic
rubbers
Cannot be seamed b. Gum tapes
in cold or wet
weather without
protection
Requires careful
compounding to
resist attack by
microorganisms
Typical Available
Lengths Thickness Reinforced
(ft) (mils) Available'
Several 10 to 30 Yes
hundred
















100 to r)00 30-45 YPS


















100 20 to 60 Yes











           3-54

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 Usually,  conditions  at  a  Superfund  site  involve  a  variety  of  chemicals  over  a
 range  of  concentrations.   Therefore,  polymeric membrane  candidates  should  be
 tested with  a  representative  mixture  of  chemicals  and  concentrations  or,
 ideally,  with  actual  samples  from the site  under study.  By using actual
 samples from the  site,  the designer obtains a better understanding  of the
 polymeric membrane's  limitations, as  well as establishing  a degree  of confi-
 dence  in  the use  of  the material.

     However, the  cover  designer  should keep testing requirements in perspec-
 tive.  Because the covering membrane  lies above  the wastes, it will not be as
 directly  exposed  to  aggressive liquids as an underlying  liner or a  sidewall.
 Possible  threats  are  capillary upward migration  of liquids, which is  con-
 sidered unlikely, or  upward migration of vapor through a pervious foundation
 soil,  possibly followed by condensation on  the underside of the membrane.
 Tests  exposing various  polymeric materials  to various waste fluids  have estab-
 lished certain incompatibilities (Haxo et a!., 1980, 1983).  However, all such
 tests  were by  direct  exposure to liquids, and as far as  is known, no  testing
 has  been  done  with membranes  exposed  to vapors.   There is  reason to believe
 (H.  Haxo, Jr.,  personal communication, 19 May 1983) that the cover  environment
 may  be markedly less  severe than that of a  liner or sidewall as regards chem-
 ical attack.

     A  big advantage polymeric membranes have (from a materials standpoint)
 over barriers  that are  fabricated in  the field (such as soil cement,  asphalt
 concrete, soil-bentonite mixtures, etc.) is  that polymerics are manufactured
 in a factory environment, where quality-control  measures can be used  that are
 either impossible or  impractical  to use in  the field.   However,  each  type of
 membrane  is  subject to  its own particular set of actual or potential  problems,
 as shown  in Table 3-13.

     Polymeric membranes manufactured  in small widths are seamed together in
 the  factory to  form large panels.  These factory seams are generally  of high
 quality.   However, for most jobs  these panels must be seamed in the field.
 The  field seam  is potentially the weakest link in the integrity of the com-
 pleted membrane, although high-quality seams are commonly achieved by modern
 seaming methods and quality-control  practices.   The quality of a field seam  is
 controlled by:   (1) the compatibility  of the seaming system with the  polymeric
 material;  (2) the skill  of the seaming crew; and (3) the ability of the seam-
 ing  system to perform in adverse  conditions  (wet, cold, dusty, hot,  etc.).

    Selection of a certain membrane material may require the use of a certain
 seaming system, and for one reason or  another a given seaming system may not
 be usable at a  given site.  Therefore  the designer must be informed regarding
 seaming systems.  As seen in Table 3-13 there is not a single seaming system
 that will  work  for every type of  polymeric material.   The seaming methods
 commonly used are:  (1)  adhesive/solvent systems; (2) systems using heat only;
 and  (3) systems using heat and extrudite.   Usually, the best source of infor-
mation concerning the proper seaming system to use is the product's
manufacturer.

    Seaming with adhesives and solvents has been the most widely used method
over the years.  Although the words  "adhesives"  and "solvents" have been used

                                      3-55

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synonymously in seaming operations,  the two are separated here to address
adhesive tapes separately.   Adhesive tapes have been used with materials that
resist solvent attack (such as butyl rubber and then polyethylene sheets).   A
fair amount of skill  is involved with its use as the alignment of the two
sheets must be very good and usually the entire length of the sheet is seamed
at one time.  The tape is basically  a double-faced tape (sticky on both sides)
which is placed along the edge of one sheet, has the protective backing re-
moved, and then has the second sheet placed on top of it (Figure 3-16(a)).
The same type of lap joint is used in a solvent seam (Figure 3-16(b)).  How-
ever, the effectiveness of a solvent seam is attributed to the solvent's
ability to attack the polymeric membrane making it "tacky."  Solvent joints
involve the application of the solvent (brush and spray applications have been
used) to both sheets, overlapping, and applying pressure for a sufficient
length of time (Figure 3-16(b)).  With solvent seams, sufficent time must be
allowed for the seam to cure before  imposing any load on it.  This curing time
allows the bond strength to develop.  A modification of the lap splice is the
tongue-and-groove splice (Figure 3-16(c)), commonly used with EPDM and butyl
rubber sheeting.

    Heat welding systems (heat only) basically melt the sides of the membranes
to be joined and follow the heat with pressure (Figure 3-17), thus creating a
fusion welding of the two membranes.  If properly done, this method provides a
strong, high-quality seam.   However, this system is very sensitive to wind,
dust, cold, and rain.

    The third seaming system is extrusion welding.  This technique employs
molten plastic (normally the same material as the polymeric membrane) and
extrudes it on top of (Figure 3-18)  or in between the membranes (Figure 3-19)
to form a seam.  This is the seaming method used in joining high-density
polyethylene (HOPE).

    Seams are subject to two failure modes, shear and peel  (Figure 3-20), both
of which must be considered when evaluating field seaming.

    To date, geomembranes have been used much more as liners than as  covers.
The information presented in this Handbook  is largely based on experience with
geomembranes in liner applications.   Because of their different respective
positions,  membranes in liner service should be more subject to attack by
liquid chemicals, while those in cover service should be more vulnerable to
vapors, ozone, or biotic agents.


         3.4.2.3 Concrete and Cement


    The use of cement  in a  hydraulic barrier manifests  itself  in  two  areas:
concrete and soil-cement.

     (1) Concrete.  Concrete  has been used  in the  past to  line water-holding
structures.  However,  concrete  was  utilized most  for this  purpose  at  a  time
when  the engineer  had  a very  limited selection of hydraulic-barrier materials
(Kays,  1977).  Problems with  cracking,  leakage at construction  joints,  costs

                                       3-56

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                           FIGURE  3-16

              TYPICAL ADHESIVE/SOLVENT  SEAMS
(1)
    solvent
               protective
                backin/
              tape
(1)
                                            remove
                                              backin
                                 (2)
                     a.  ADHESIVE (GUM)  TAPE SEAM
                                  overlap
       (2)


b.  SOLVENT SEAM
                                                                  lap joint
                                                             (3)
                                                                        pressure
                                               11
                                                                      (3)
                       h-2"
         6" min.•
 factory-vulcanized  tab
  membrane
(Courtesy E.I.  du Pont de Nemours & Co.  Inc.)
                                                      adhesive (gum)  tape
                                                  /      membrane
                          * Manufacturers recommend use  of both tape
                            and solvent on both sides of joint for
                            EPDM and  butyl rubber membranes


                       c.  TONGUE-AND-GROOVE  SEAM
                                3-57

-------
   FIGURE 3-17



  HEAT WELDING
HEATING ELEMENT
     PRESSURE



      \  I
     T
       3-58

-------
                  FIGURE 3-18

     EXTRUSION WELDING SYSTEM  -  TOP-LAID
NO EXTRUDITE
BETWEEN SHEETS
HERE ^
EDGES OF SHEETS ARE MELTED
AND EXTRUDITE IS MIXED IN
                             ORIGINAL SHEET EDGE
                      3-59

-------
              FIGURE 3-19

EXTRUSION WELDING SYSTEM - INTERMEMBRANE
      PRESSURE
      I   I   I
EXTRUDITE IS INTRODUCED
BETWEEN SHEETING
                   3-60

-------
                                  FIGURE 3-20

                              SEAM FAILURE MODES
                                         seam
                                    a.   SHEAR
                    *=>
                                   b.   PEEL
of labor and materials,  and the advent  of  cheaper, more  flexible materials
have kept concrete from  being used extensively  as a  hydraulic barrier in the
field of waste disposal.   For these reasons  the discussion of concrete will be
limited to this section  and not included in  the section  on design.

    The following factors  are important in the  design of concrete (reinforced
and nonreinforced) as  a  hydraulic  barrier  (in a cover system):

    •    Subgrade

    •    Side slope

    •    Concrete mix

    •    Joints and waterstops

    •    Type of reinforcement (reinforced concrete  only)

    •    Curing

                                     3-61

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    In reinforced versus unreinforced concrete,  there are advantages and dis-
advantages connected with either.   Unreinforced  concrete is cheaper, and is
usually considered hydraulically tighter,  as closer joint spacing is usually
required.   With smaller panels,  less space will  be created at joints due to
contraction of the concrete.   On the other hand,  unreinforced concrete is
highly dependent on a stable substrate and is more susceptible to cracking due
to thermal effects while exposed.   A good  source of information on the design
and testing of concrete is  the US Army Corps of  Engineer's "Handbook for Con-
crete and Cement."  A discussion of concrete in  construction may also be found
in Backstrom et al.  (1974).

    (2)  Soil-cement.  Soil-cement is created by a process in which onsite
soils, or soils imported from other areas, are mixed with portland cement and
water, and compacted.  Soil-cement has been used to line water impoundments
and canals and to provide embankment protection  for dams and shorelines.
Soil-cement has found its greatest use in  areas  where clay or clayey soils are
not found within economical  distances of the site, but sandy soils are avail-
able.  Because soil-cement is a relatively brittle material, careful attention
must be given to the supporting substrate.  Also some special consideration
must be given to the bonding of lifts and  to curing; these items are discussed
in Chapter 4.

    Soil-cement is essentially a mixture of portland cement and a sandy,
usually well-graded soil (maximum aggregate size - 3/4 inch).  As a general
rule, any soil that can be pulverized easily and contains less than 50 percent
silt and clay is suitable for soil-cement  construction (Kays, 1977).

    Generally there are two categories of  soil-cement; compacted soil-cement
and plastic soil-cement.  Compacted soil-cement differs from the plastic mix
in the amount of water added to the mixture.  Compacted soil-cement is com-
pacted at or near the mixture's optimum moisture content.  Plastic soil-cement
has a consistency like plaster or mortar,  which require more water and cement
than the standard mix.  Although the compacted soil-cement mix is more com-
monly used, plastic soil-cement has been shown to be practical for small areas
or where larger equipment cannot be used.

    In the design and construction of a soil-cement hydraulic barrier the fol-
lowing criteria must be considered:

    •    Cement quality

    •    Cement content

    •    Optimum moisture content

    •    Density

    •    Permeability

     •   Effects of freeze-thaw cycles

     •   Effects of cycles of wetting and drying

                                      3-62

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    •    Compaction (field control)

    •    Bonding

    •    Curing

    Table 3-14 presents some general guidance for the average cement content
required for different types of soils.   However, the soil-cement mixture
should be designed on the basis of a laboratory testing program.   Table 3-15
presents a list of design criteria and some representative laboratory tests
used to acquire these parameters.

    One of the parameters important to the soil-cement layer's ability to func-
tion as a hydraulic barrier is permeability.   Table 3-16 gives some examples of
the permeabilities of cement-treated soils.  From Table 3-16 one can see that
as the percent-by-volume cement content increases, the coefficient of perme-
ability decreases for a given soil.  However, cement content is not the only
factor by which the permeability of soil-cement is affected.   The degree of
compaction plays an equally important role.  A rule of thumb has been that a
soil-cement layer must be compacted to at least 95 percent Standard Proctor
density.  However, this will be borne out or refuted in the laboratory testing
program.

    The nature of the fluids to which the barrier may be exposed is another
matter that should be considered.   Acids and alkalies may attack the cement.

    Methods of constructing a soil-cement layer are described in Chapter 5,
"Construction."

    The cost of a soil-cement layer depends primarily on two factors, the cost
of processing and the cost of cement.   The cost of processing includes the
costs of processing material, hauling materials to the site,  water for curing
and mixing, central-plant mixing,  transporting the soil-cement at the site,
spreading, compacting, and curing.  The cost of cement includes delivery and
contractor's cost.  The cost of processing is somewhat quantity-dependent.
The Portland Cement Association (PCA) lists approximate 1982 costs as follows:

    Less than 5,000 cubic yards -  $13.75/cu yd

    5,000 to 10,000 cubic yards -  $12.00

    10,000 to 40,000 cubic yards - $10.50

    40,000 to 100,000 cubic yards  - $9.00

    More than 100,000 cubic yards  - $8.25

    The PCA also states that a 6-inch layer of soil-cement costs about $0.507
square foot ($27.00/cubic yard) installed.
                                      3-63

-------
                             TABLE 3-14
               AVERAGE CEMENT REQUIREMENTS FOR EXPOSED
                     SOIL-CEMENT SLOPE PROTECTION
      Unified Soil
     Classification
         Symbol
          Average Cement
         Content (percent
            by weight)
GW
GP
GM
GC
SW
SP
SM
SC
CL
CH
ML
MH
7
7-8
8-9
9
7-8
7-11
8-12
9-12
12
--
12
~ ™"

                             TABLE 3-15
                 REPRESENTATIVE LABORATORY TESTS FOR
                    SOIL-CEMENT DESIGN PARAMETERS
       Parameter
 Laboratory Test Designation
Cement Quality

Cement Content
Optimum Moisture Content
Maximum Density
Permeability
Freeze-Thaw Effects
Wet-Dry Effects
Soil Classification
ASTM C150, CSA A5, AASHTO M85,
ASTM C595, AASHTO M240
ASTM D558
ASTM D559
ASTM D560
ASTM D2434
ASTM D560
ASTM D559
ASTM D2487, AASHTO Ml 45
                                 3-64

-------
CO
                                                                          TABLE  3-16



                                                        PERMEABILITY  OF  CEMENT-TREATED SOILS
Soi 1 Number
or Sample
Identification
Standard
Ottawa sand

SP soil,
11 H-26
Idaho

Graded Ottawa
sand

PCA soil
No. 7018
Florida

PCA soil
No. S-2
11 1 inois

PCA soil
No. 6998
Maine

PCA soil
No. 6863-2
Maryland

SP sand,
11 H-X65
Utah
PCA soil
No. 7019
Florida

Dry
Density,
pcf
108.2
112.8
117.6
—
98.6
99.8
100.3
103.2
104.7
107.4
101.0
100.9
103.6
105.3
100.8
99.9
104.0
.104.8
104.8
107.2
111.7
113.4
104.9
106.6
112.4
114.4
100.1
105.8
109.3
101.0
106.7
108.2
108.8
Moisture
Content,
Percent
10.8
9.4
9.7
_.
24.1
20.1
18.8
13.7
13.6
12.3
12.2
13.3
12.3
12.0
14.9
14.7
15.1
15.1
10.6
9.5
10.3
10.2
10.3
10.8
10.3
10.3
16.0
14.8
13.5
13.8
13.3
13.4
13.4
Cement
Content
Percent
by Volume
0
5.7
11.3
0
8
8
20
0
5.3
10.3
0
3.1
6.3
9.2
0
3.1
6.3
9.2
0
3.3
6.8
9.9
0
3.3
6.8
10
0
6
12
0
3.1
6.5
9.5
Type of
Soil -Cement
Compacted
Compacted
Compacted
Plastic
Plastic
Plastic
Plastic
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
K, Coefficient
of Permeability,
ft per year
48,750
6,940
76.3
2,460
130
130
0.8
16,300
473
21.4
746
562
192
21.1
4,960
1,359
59.5
11.5
2,400
651
36.2
7.6
1,640
90.3
25.6
3.6
356
19.8
1.1
144
33
0.3
0.02
USDA
Texture
Coarse
sand

Sand



Sand


Sand



Fine
sand


Coarse
sand


Sand



Fine
sand

Fine
sand


Cement
AASHTO Requi re-
Gradation Analysis, Percent Passing Soil ment b^h
3/4 4 10 40 200 .05 .005 Class Volume
(100% pass #20; 0% pass #30) A-l-b(O)


100 99 98 73 983 A-3(0)



100 100 100 #50 #100 -- — A-l-a(O)
28 2

100 100 100 91 7 1 — A-3(0). 10.0



100 100 100 96 13 12 2 A-2-4(0) 8.0



100 100 96 51 52 — A-3(0) 7.0



100 100 100 77 4 — — A-3(0) 8.5



100 99 99 96 661 A-3(0)


100 100 100 94 2 — -- A-3(0) 11.0



   aAll  soils nonplastic.




   bCement requirement based on ASTM Standard Freeze Thaw and Wet-Dry Tests  for Soil-Cement Mixtures and PCA Paving  Criteria.



   Source:  Portland Cement Association's Soil-Cement Information Bulletin IS173.02W

-------
    3.4.3 Permeable Materials
    Permeable nonsoil materials include bulk residual  or waste materials from
various industries, drainage pipes and tiles, and geotechnical fabrics known
as "geotextiles."  Residual materials comprise both organic and inorganic
wastes.

    In considering any material, the designer will consider its functional
suitability and cost.  At any given site, a residual material  may be available
locally at low cost.   If so, the designer must determine whether the material
is suitable for cover applications.  Residual materials proxy for soils, and
share a good deal in common with them.   Residual materials possess a gradation
and various measurable bulk properties, and may be classified by the USCS.  A
residual material is likely to be similar to a natural soil with the same USCS
group symbol, although some qualitative differences are likely.


         3.4.3.1  Organic Residual Materials


    Organic residual materials are generated largely by the paper and forest-
products industries.  ,In the same way that organic soils are generally unde-
sirable from an engineering viewpoint because of inferior mechanical proper-
ties, organic residuals are generally undesirable in the same way.  Paper-mill
slimes, probably the most common organic residual, are fine in size, low in
density, high in water content and difficult to dry out.  Sawdust and wood
chips, which formerly were mostly burned, are now largely recycled within the
forest-products industry.  These, however, might find application in a cover
system as a soil  amendment to promote vegetative growth.  Such use should be
planned with guidance from competent agronomical experts.


         3.4.3.2 Residual Materials from the Mining and Metallurgical
                 Industries


    The largest quantities of inorganic residual materials are generated in
the mining and metallurgical industries.  These materials include mine and pit
wastes, mine mill tailings, furnace slag, and others.   An extensive research
program was conducted for the Federal Highway Administration on the potential
use of mining wastes as highway materials, and reported in four volumes under
the general title of "Availability of Mining Wastes and Their Potential for
Use as Highway Material" (Collins and Miller, 1976; Collins, 1976a, 1976b;
Collins and Miller,  1977).  Those parts of a cover system that function as a
foundation or as a subsurface drainage member have counterparts in highway
construction.  In addition, both highway engineers and cover designers face
the problem of handling surface drainage and of preventing erosion on slopes
or in channels.  The above-named series of reports presents a wealth of infor-
mation on mineral waste materials, including practical use experience in vari-
ous highway applications and an extensive discussion of the economics of
shipping bulk materials by truck, train, and barge.

                                      3-66

-------
    In general, mineral residuals of coarse grain size are more useful than
fines.  Thus slags, waste rock, and the coarser fractions of various mineral
tailings tend to find acceptance as materials for highway use.  The fines tend
to be unacceptable because, being the products of crushing and grinding of
rock, they are nonplastic rock flours or silts, having little or no cohesion.
Such materials are highly susceptible to erosion, highly susceptible to frost
heaving where that is a problem, and lacking in surface-active properties such
as cation exchange capacity, so that they are infertile.  Thus fines, to some
extent including fly ash (discussed below), may find applications as additives
or blending media, but generally fail to find productive uses as an unaccom-
panied material.


         3.4.3.3 Fly Ash


    Fly ash (FA) is a residual material of a somewhat special character.   For
one thing, FA is generated in large and fairly constant quantities; for an-
other, it has achieved acceptance as a standard construction material in the
concrete industry, being the subject of three ASTM specifications (C-311,
C-593, C-618).   FA has received much study, research and testing, and as a
material is well documented.   In the context of the electric utility industry,
where most FA is produced, it is a residual product requiring storage and
disposition; but in other contexts it is definitely a resource and a raw
material.

    Most FA is formed during the combustion of pulverized coal.   At the high
temperatures during firing, the noncombustible mineral matter in the coal is
fused into molten Droplets, which on cooling congeal to form glassy spheres.
Microphotographs of FA show it to be an assemblage of nearly perfect spherical
particles.   The specific gravity of FA is lower than most common soil minerals,
averaging about 2.4,  and there is reason to believe that some of the FA spheres
are hollow.   Chemically the FA is siliceous, aluminous, and iron-bearing, with
variable lesser quantities of other oxides, mainly CaO, MgO, Na20,  and S03.
The percentage of silica (Si02) varies between about 30 and 55 pet.   There is
a systematic tendency for Western-US FA's to be high in lime (CaO)  and for
Eastern ones to be low.   Because any lot of FA reflects the coal  from which it
was formed,  the chemistry of FA's is variable.

    Considered as a soil,  FA is a fairly uniformly graded silt,  with median
size (D50) ranging roughly between 20 and 40 microns.   FA is extremely non-
plastic, as  might be  expected from its spherical  grain structure.   As is
common with  silts, FA is seriously erosion-prone and frost-action-prone.   As
expressed by DiGioia  and Nuzzo (1972), FA is "a dusty nuisance when dry and an
unmanageable quagmire when saturated," but can be easily handled and compacted
at intermediate water contents.   For a set of Western Pennsylvania  FA's,  these
authors indicated maximum dry densities in the Modified Proctor test (see
above) ranging between 77 and 89 pcf.   The densities are quite low  in compari-
son with most soils,  and reflect the low specific gravity of FA.

    Most FA's are pozzolanic,  and this property has been the basis  of most of
FA's industrial  use.   A pozzolan is a siliceous or siliceous-aluminous material

                                      3-67

-------
which, in the presence of moisture,  will  react with lime to form a cementitious
compound.  Most FA's are also distinctly alkaline.

    There are obvious economic incentives to develop uses for FA.   Several
organizations promote established uses and the search for new ones, and there
have been several research symposia, both in North America and abroad, devoted
to ash utilization.   A summary of applications and technology was published in
1970 by the U. S. Bureau of Mines (Capp and Spencer, 1970).  The established
avenues of application for FA are in the field of cement and concrete; as a
light-weight aggregate in concrete and building blocks; in engineering soil
stabilization; as a mineral filler in asphalt mixes; in agriculture; and in
brick manufacturing.  The soil-stabilization and agricultural applications may
be pertinent to cover systems.

    The vegetative component of a cover system may benefit from mixing of FA
into the plant-supporting soil.  The silty size of FA promotes a loamy soil
texture, which is favorable for plant growth.  FA may be a source of nutrients,
and may be capable of delivering them over extended periods.  Moreover, the
alkalinity of FA may act as an effective neutralizer for acid soils.  Seasoned
ash is preferable to raw ash, as the latter may show some plant toxicity; the
elements producing the toxicity are quickly leached away in the seasoning pro-
cess.   The cover designer is advised to consult research reports for detailed
discusssions of FA's agricultural effects.

    In engineering soil stabilization, FA's pozzolanic properties come into
effect.  Greater or lesser amounts of lime, depending on the lime content of
the FA, need to be added for the stabilization reaction to occur.  A careful
review of such use has been published by Barenberg (1974).  Materials to which
LFA (lime, fly ash, aggregate) or LCFA (lime, cement, fly ash, aggregate) sta-
bilization is appropriate are coarse-grained soils (gravels and sands) and
other coarse-grained aggregates such as crushed rock and various slags.  This
requirement agrees in general with recommended practice in "Soil Stabilization
for Pavements" (Depts. of the Army, Air Force, and Navy, 1982).  Various fac-
tors are important for production of an acceptable result, including proper
mix, proper compaction, and proper curing conditions and time.  The result is
a relatively hard, rigid material with good durability and dimensional sta-
bility.  According to Barenberg (1974, pp 186-7) the stabilized material has
the property of autogenous healing.

    Published permeability data on FA-stabilized soil are scarce.  Parker,
Thornton, and Cheng (1977) reported on permeability testing of two Arkansas
soils with which a Western-US fly ash with very high lime content  (20.0 per-
cent CaO) had been mixed.  Only one of these soils, a SP-SM (USCS), was an
appropriate type for FA stabilization; the other was an organic clay  (OH), an
uncommon soil.  Barenberg (personal communication, 24 March 1983)  reports that
the stabilized material can be made quite impervious, and that k values as low
as 10"8 cm/sec can be achieved with proper gradation and compaction.

    Whether FA should be considered for use  in a cover system, other  than for
agricultural purposes as discussed above, requires judgment on the part of the
designer.  Placed over an unstable, settlement-prone foundation, an FA-
stabil ized soil, or any stabilized soil,  is  threatened with cracking,  an

                                      3-68

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obviously undesirable condition for prevention of percolation.  If there is
assurance that the wastes are reasonably stable and if a thick enough stabi-
lized layer can be placed, strong enough to bridge minor underlying slumping,
it is reasonable to expect that a durable and effective cover could be pro-
duced.  There is no known actual experience to date with the use of such a
design.
         3.4.3.4 Other Residual Materials
    Other residual materials include boiler bottom ash and slag, incinerator
residues, foundry sand, plant sludges, reservoir and channel silt, dredged
material, and composted sewage sludge (Lutton, Regan, and Jones, 1979).   Any
of these may in special circumstances be considered for cover applications.
The cover designer should determine a given material's properties and, by
comparison to soils or other known materials, decide whether the material can
suitably be used in the cover.


         3.4.3.5 Pipes and Tiles


    Subsurface drainage systems have been constructed using a variety of mate-
rials.  These materials have included sands and gravels; pipes of various mate-
rials (vitrified clay, concrete, steel, plastic, etc.); and geotechnical fab-
rics.  Of these materials, sands and gravels have the longest history of use
as underdrainage materials.   The use of sand and gravel can be primarily
attributed to their durability, low cost, and availability.

    A system employing only sand and gravel has a lower drainage capacity than
one that includes a system of pipes and/or drainage tiles to intercept and
transport the infiltrated water to an outlet.  Design and construction consid-
erations for such a system are presented in section 4.7.  The pipes and tiles
used in the drainage layer should meet the strength and durability requirements
imposed upon them by the site conditions as well as carry their designed flow.

    Current specifications covering the quality of the materials are presented
in Table 3-17.   These specifications should be used as guidance in determining
a product's acceptability for use in a drainage installation.   However,  there
are some acceptable modifications to these specifications, given site-specific
conditions.   For example, if a clay tile will not be subjected to damage from
freezing and thawing before, during, and after installation, the testing
related to freeze-thaw effects can be modified or waived.

    Much of the use of buried pipe and tile has been in the field of agricul-
tural drainage.   Information on this subject can be obtained from "Drainage
for Agriculture" (Van Schilfgaarde, 1974).   Materials and methods are partic-
ularly discussed in Fouss (1974) and Willardson (1974).   Agricultural drains
are also discussed in Bouwer (1978).
                                      3-69

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                                  TABLE 3-17
             DRAINAGE-MATERIALS SPECIFICATIONS (LEE ET AL.f 1984)
                                                            Specification
Clay drain tile
Clay drain tile, perforated
Clay pipe, perforated, standard, and extra
  strength
Clay pipe, testing
Concrete drain tile
Concrete pipe for irrigation or drainage
Concrete pipe or tile, determining physical
  properties of
Concrete sewer, storm drain, and culvert pipe
Reinforced concrete culvert, storm drain, and
  sewer pipe
Perforated concrete pipe
Portland cement
Asbestos-cement non-pressure sewer pipe
Asbestos-cement perforated underdrain pipe
Asbestos-cement pipe, testing
Pipe, bituminized fiber (and fittings)
Homogeneous perforated bituminized fiber pipe
  for general drainage
Homogeneous perforated fiber pipe, testing
Laminated-wall bituminized fiber perforated pipe
  for agricultural, land, and general drainage
Laminated-wall bituminized fiber pipe, physical
  testing of
Styrene rubber plastic drain and building  sewer
  pipe and fittings (perforations, if needed,
  are specified in ASTM D 2311)
Plastic drainage  tubing, corrugated

Pipe, corrugated  (aluminum alloy)
Pipe, corrugated  (iron or steel, zinc coated)
ASTM C 4
ASTM C 498
ASTM C 700

ASTM C 301
ASTM C 412
ASTM C 118
ASTM C 497

ASTM C 14
ASTM C 76

ASTM C 444
ASTM C 150
ASTM C 428
ASTM C 508
ASTM C 500
Fed. Spec. SS-P-1540
ASTM D 2311

ASTM D 2314
ASTM D 2417

ASTM D 2315

ASTM D 2852


Soil Conservation
Service  Specification
Fed. Spec. WW-P-402
Fed. Spec. WW-P-405
                                      3-70

-------
         3.4.3.6 Geotextiles


    The term "geotextile" or "geotechnical fabric" refers to an uncoated
synthetic textile product that can be incorporated into an engineered  structure
and the uses of which do not require it to be watertight.  Geotextiles usually
fulfill five basic functions (or combinations thereof):

    •    Filtration

    •    Drainage

    •    Separation

    •    Reinforcement

    •    Armoring

Table 3-18 defines these functions more fully.

    These functions can be used for a variety of practical applications.   How-
ever, the designer should note that in performing its primary function, the
geotextile may be performing a secondary function that the designer might ex-
ploit.   Table 3-19 presents examples of some practical applications of geotex-
tiles as well as the primary and secondary functions associated with them.

    After primary and secondary functions have been established, the next step
is determining the most suitable geotextile for the application at hand.   An
evaluation should be based on four characteristic areas:

    •    Construct!'bi 1 ity

    •    Durability

    •    Mechanical characteristics

    •    Hydraulic characteristics

Within each area, the designer must consider a group of properties in deter-
mining a geotextile's suitability.   Although these properties may vary some-
what between fabric functions,  many are held in common.   Table 3-20 presents
these properties as they relate to the different characteristic areas (cri-
teria for selection).

    Geotechnical fabrics are manufactured from a variety of synthetics, in-
cluding polypropylene, polyester,  polyethylene,  nylon, polyvinylidene chloride,
and fiberglass.   The most commonly used are polypropylene and polyester.   The
physical properties of all  these materials can be varied considerably by vary-
ing the additives used in the manufacture and the methods of processing the
filaments.   Therefore, careful  consideration must be given to the types of
polymers present in a geotextile and the manufacturing process that produced
it.   Generally,  the same scrutiny should be applied to geotextiles as to

                                      3-71

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                                   TABLE  3-18

                       DESCRIPTION  OF  GEOTEXTILE  FUNCTIONS
    Function                                   Description


                       The process of allowing water to escape easily  from  a
     Filter             soil unit while retaining the soil  in place.  The water
                       is carried away by some other drain  (e.g.,  rock or rock
                       with pipe).
    Drain              The situation where the fabric itself is to carry the
                       water away from the soil to be drained.
                       The process of preventing two dissimilar materials from
                       mixing.  This is distinct from the filtration function,
  Separation           in that it is not necessary for water to pass through
                       the fabric.
Reinforcement          The process of adding mechanical strength to the soil-
                       fabric system.
                       The process of protecting the soil from surface erosion
    Armor              by some tractive force.   Usually in these situations,
                       the fabric serves only for a limited time.
Source:   Bell, Hicks, et al.  (1980)


synthetic membranes, as regards their compatibility with substances and condi-
tions to which they will be exposed in service.

    The most commonly used method of general geotextile classification is by
manufacturing process.   Geotextiles are classified as woven, nonwoven, and
knitted.  Woven fabrics are made as the name implies.  The geotextile is manu-
factured in a process similar to that which produces clothing material.   Weav-
ing tends to produce fabrics with relatively high tensile strengths and moduli
(ratio of tensile stress to tensile strain).  However, these fabrics have a
relatively low elongation at rupture, and their modulus is greatly dependent
upon the orientation of the fibers to the load.   If the fabric is loaded on a

                                      3-72

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                                  TABLE 3-19

             APPLICATIONS AND CONTROLLING FUNCTION OF GEOTEXTILES
  Primary
  Function
         Applications
  Secondary Function(s)
Filter
Trench Drains
Pipe Wrapping
Base Course Drains
Frost Protection
Structural Drain
High Embankments
Separation Drain
Separation, Reinforcement
Drain
Drainage
Retaining Walls
Vertical Drains
Horizontal Drains
Reinforcement
Erosion
Control
(Armor)
Culvert Outlets                   Filter
Seeding, Mulching                 Filter
Ditch Armoring                    Filter
Embankment Protection Scour       Filter
Reinforcement
Reinforcement over soft ground
Retaining Structures
Fill Reinforcement
Drain, Separation
Drain, Separation
Separation       Paved Roads
                 Working Platform
                 Railroad
                 Aggregate Surfaced Roads
                                  Reinforcement
                                  Reinforcement
                                  Reinforcement
                                  Reinforcement
Source:   Adapted from Bell, Hicks, et al.  (1980)
bias, a dramatic decrease in the fabric's modulus occurs (although the ulti-
mate breaking strength may increase).   Also, the manufacturing process is the
most expensive.

    Nonwoven fabrics are produced in a process by which continuous filaments
or staple fibers are laid on a supporting screen or belt (to form a mat) and
then bonded by one of the processes described below (Horz, 1983):
                                      3-73

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                                     TABLE 3-20

         IMPORTANT CRITERIA AND PROPERTIES FOR  EVALUATING  A GEOTEXTILE
   Criterion
                Property
Constructibility
Durability
 Mechanical
 Characteristics
 Hydraulic
 Action
Fabric Strength
Temperature Stability
UV Light Stability
Wet and Dry Stability
Flammability
Thickness
Weight
Absorption (Wet Weight)
Puncture Resistance
Cutting Resistance
Modulus
Specific Gravity
Flexibility
Tear Resistance
Seam Strength

Ultraviolet-Light Stability
Chemical Stability
Biological Stability
Thermal Stability
Wet-and-Dry Stability
Abrasion Resistance
Animal, Vegetable, and  Insect  Resistance
Tensile Strength
Fatigue
Seam  Strength
Burst  Strength
Puncture Resistance
Tear  Strength
Fatigue
Creep  - Static
Creep  - Dynamic
Friction/Adhesion
Modulus -  Static0.
Modulus -  Dynamic
Thickness
 Permeability
 Siphoning  Capacity
 Pumping Resistance
 Piping Resistance
 Intrusion  Resistance
 Clogging  Resistance
 aAll may not be important for every application


  Applicable to reinforcement function only

 Source:  Adapted from Bell, Hicks, et al.  (1980)
                                         3-74

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    •    Needle punching.  Bonding by needle punching involves pushing many
         barbed needles through the fiber mat normal to the plane of the
         fabric.   The process causes the fibers to be mechanically entangled.
         The resulting fabric has the appearance of a felt mat.  The size of
         the needles determines the sizes of the largest openings in the
         fabric,  but the complex structure of the matted filaments determines
         the overall permeability and pore characteristics.  Needle-punched
         fabrics  can be formed by needling a single mat thickness or by nee-
         dling several mat thicknesses together.

    •    Heat bonding.  In this process the mat is laid and then the fibers
         are bonded at some or all of the points where fibers cross one an-
         other.  This can be done by incorporating fibers of the same polymer
         type but having different melting points in the mat or by using
         heterofilaments, that is, fibers composed of one type of polymer on
         the inside and covered or sheathed with a polymer having a lower
         melting  point.  With heterofilament bonding, up to 100 percent of the
         fiber crossover points can be bonded, the number of bonds being con-
         trolled  by the percentage of heterofilaments in the mat.

    •   Resin bonding.  Resin is introduced into the fiber mat, coating the
         fibers and bonding the contacts between fibers.

     •   Combination bonding.  Sometimes a combination of bonding techniques
         is used  to facilitate manufacture or confer desired properties.
         Since needle punching tends to leave the fibers relatively free to
         move with respect to each other, heat or resin bonding can be com-
         bined with it to increase the dimensional stability of the fabric.
         Very open woven fabrics are also sometimes coated to fix filament
         positions.

    Combination fabrics are fabrics which combine two or more of the fabrica-
tion techniques previously described.   The most common combination fabric is a
nonwoven mat that has been bonded by needle punching to a woven scrim.   The
nonwoven mat may  be on one or both sides of the woven backing.

    The knitting  process is not a commonly used manufacturing process.   In
fact, only two fabrics are known to be made by this process (Horz, 1983).   One
is employed in surface erosion protection, while the other is used for unidi-
rectional soil reinforcement.  The advantages of the knitting process are that
the strength properties can be varied unidirectionally or multidirectionally,
it is possible to knit tube shapes, and the process is less expensive than
weaving.

    Table 3-21 presents general guidance as to the types of geotextiles that
have been applied in various practical uses.
                                      3-75

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                                  TABLE 3-21

              GEOTEXTILES USED FOR VARIOUS PRACTICAL APPLICATIONS

USE
Drain Filter
Separation: Light Duty
Separation: Heavy Duty
Reinforcement: Light Duty
Reinforcement: Heavy Duty
Erosion Conrol : Light Duty
Erosion Control: Medium Duty

FABRIC
Lightweight Bonded and Lightweight
Needled Nonwoven and Slit Film and
Monofilament Woven
Lightweight Bonded and Lightweight
Needled Nonwoven and Slit Film Woven
Mediumweight Bonded and Mediumweight
Needled Nonwoven and Slit Film Woven
Monofilament and Slit Film Woven and
Heavy Needled Nonwoven
Mul tifilament Woven
Lightweight Bonded and Lightweight
Needled Nonwoven and Slit Film and
Monofilament Woven
Slit Film and Monofilament Woven and
Mediumweight Bonded and Mediumweight
Needled Nonwoven
Erosion Control:   Heavy Duty
Very Heavyweight Needled Nonwoven,
Heavyweight Woven, and Special  Heavy-
weight Combination Woven-Nonwoven
Fabrics
     Silt Fences
Lightweight Bonded and Lightweight
Needled Nonwoven and Slit Film Woven
Drainage
Heavyweight Needled Nonwoven
Source:   Bell, Hicks, et al.  (1980)
                                        3-76

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                                    CHAPTER 4

                            DESIGN OF A COVER  SYSTEM
4.1  Introduction


     4.1.1 Basic Considerations


     In designing a cover system, three basic issues must be considered:

     •   Design life of cover system

     •   Primary function of cover

     •   Future use

     The term "design life" refers to the span of time during which the cover
system (al1 of its elements) will perform as expected.  This time requirement
will  be one of the primary motivators as to the types of materials that can be
used, as well as the overall design philosophy.   For instance, if installing a
cover over an uncontrolled hazardous waste site is all that is to be done,
then  the "design life," for all intents and purposes, may well be considered
indefinite.  On the other hand, if the cover is installed in conjunction with
a system that will ultimately render the site safe within a finite period
(such as leachate recovery and treatment program), then the cover design
should reflect this.   However, beyond a certain length of time the terms
permanent and temporary become arbitrary.   Generally, if an engineered product
is expected to last for more than 50 years it is considered permanent.   There-
fore, the cover-system designer is faced with the decision of either using a
material that will last the "design life"  of the cover system or designing a
system that allows those elements that will  not last the design life to be
replaced without affecting the cover's efficiency.   An example of this can be
seen  in the choice of a material to act as a hydraulic barrier in a cover
system with a design life of 30 years.   Given site-specific conditions, the
designer may choose a material such as a clay which could normally be expected
to last the entire "design life" of the cover (if not disrupted by vegetation).
The designer might also elect to use a polymeric material with the stipulation
that  it be replaced or a reinstallation made over the old cover system within
the required lifetime of the cover.   The normal  lifespan of most polymeric
membranes is generally considered to be 20 years,  but this is uncertain,
because few field installations of membranes have been in place this long.
One may note that Government regulations as  well as financial  considerations

                                      4-1

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(such as estimating future costs with the degree of confidence necessary)
normally act as an incentive toward using materials that will  last the design
life of the cover system.

    A factor that ties in closely to the "design life" concept is the function
that the cover is designed to fulfill, whether it should function as a "leaky
roof" or as a "watertight roof."  The type of roof will  depend on the decision
as to how much water will  be allowed to percolate through the  site.   If the
function of the cover is to reduce the flow of contaminants leaving a site to
some acceptable level, then the cover's design should reflect  this.   If the
cover system is expected to intercept any water percolating toward the waste,
then the designer must choose a system and materials that will meet that end
with a required degree of confidence.

    In considering the future use of a site, the designer, along with the
regulatory agency, should consider whether the public will ever have access to
the site.   This is an important question from the standpoint that many normal
land-use activities (farming, installing septic tanks, basements and water
wells, etc.) will penetrate the cover system and violate its integrity.   These
land uses may also place the public in close proximity to where the waste was
placed.   This raises a question in the basic philosophy of the design of the
cover system.  If the cover system (in conjunction with the remedial action as
a whole) will serve to isolate or encapsulate the waste and the future use of
the site includes access to the public, then will the waste still be poten-
tially harmful when and if the cover is penetrated?  This question relates to
the choice of the cover system's primary function (leaky or watertight).   A
watertight cover is essentially futile unless the public is unequivocally
denied access during the design life of the system.   Although  the question of
future use may have been decided before the designer is involved, it is an
important overall consideration.  Moreover, if it is not resolved, the cover
designer might be blamed in the future for a failure that was  not under his
control.

    One of the greatest challenges facing a cover system may be maintenance,
over the long term, of both an intact, impervious hydraulic barrier and a
stable vegetative community at the surface.  The natural tendency of vegetation
is to establish itself in diverse communities, with some species projecting
their roots downward, seeking water from deeper levels than others.   In the
process, the roots not only break up the soil, but tend to penetrate any
barrier that stands in their way.  The long-term stability of  membranes,
either synthetic or of clay, exposed to root attack is undemonstrated.


    4.1.2 Structure of a Cover System


    Figure 4-1 presents a schematic of the elements that may be found in a
multilayered cover system.  Not all elements may be required for any given
site, but it is likely that cases will exist where all of the  cover elements
are required.  Which elements are needed will be determined on a site-specific
basis.
                                      4-2

-------
             FIGURE 4-1



      STRUCTURE OF A COVER SYSTEM
SURFACE (VEGETATIVE SUPPORT)
           FILTER(S)
        BIOTIC BARRIER
            DRAINAGE
     HYDRAULIC BARRIER
    FOUNDATION (BUFFER)
            FILTER(S)
          GAS CONTROL
            WASTE
                 4-3

-------
    The uppermost layer is called the surface or vegetative layer.   Its pri-
mary requirements are to:

    •    Provide for vegetative growth

    •    Minimize wind and rain erosion

    •    Resist cracking

    •    Resist freeze-thaw deterioration

    •    Preserve slope stability

    •    Provide protection from the elements for the layers below it

    •    Provide a compatible host material  for the site's surface water
         management program

    •    Provide an aesthetically pleasing appearance

    The second layer shown is a filter layer.  Its function is to prevent
migration of fine particles in the surface layer into the coarser-grained
layer immediately below.  Filter layers are required whenever materials of
strongly contrasting gradation are placed adjacent to one another and ground-
water percolation is possible.  A filter layer may or may not be needed in a
given cover system.

    The next layer's purpose is to resist the intrusion of plant roots and
burrowing animals.  Although the presently most feasible method of controlling
penetration of plant roots lies in the careful selection of short-rooted
grasses, research is underway by various facilities (Los Alamos National Labo-
ratory, Pacific Northwest Laboratories, Illinois State Geological Survey,
etc.) on utilizing other methods such as sand, gravel, and cobble mixtures and
pelletized herbicides to prevent root intrusion into underlying wastes.  Re-
search aimed at defeating burrowing animals has also been pursued.

    Underlying the biotic barrier is the drainage layer, whose function is to
intercept water that percolates through the upper layers and divert it to a
collection and disposal system.

    The next layer is the hydraulic barrier, whose primary function is to pre-
vent or impede the passage of any downward-percolating water that comes into
contact with it.  Together, the barrier and drainage layers perform the pri-
mary function of a roof:  intercepting the downward flow of water and dispos-
ing of it safely.

    Underlying all of the previously mentioned cover layers is the foundation
layer, which provides a stable working surface from which to construct the
rest of the cover system.   It is essential to recognize that, up to this
point, none of the cover elements is intended to act as a structural entity.
In other words, the upper cover elements are not intended to hold the cover
system together; rather their integrity depends on the stability of the

                                      4-4

-------
substrate beneath them.  The foundation layer may provide part of this sup-
port, but it cannot be relied on as a subsidence preventative.  The foundation
layer should be considered as providing a working and supporting surface; but
any massive subsidence such as that generated by the collapse of waste pack-
ages or soil bridges between packages, or cavities in the soil or rock beneath
the wastes, should be handled in a stabilization program (which is not in-
cluded in the scope of cover design).

    Between the foundation layer and the wastes may be incorporated a gas-
control layer to intercept any gases that may evolve in the wastes and, by
proper venting, relieve any pressure from these gases that might build up
behind the hydraulic barrier.  If need be, a filter layer may be required as
shown.

    At the base of the system, of course, lie the wastes themselves, and any
temporary covering soil that may have been placed in the past.


    4.1.3 Design Procedure


    Figure 4-2 presents a flow diagram outlining a general  approach to the
problem of preparing a cover-system design.   Figure 4-3 presents a flow chart
for review of potential problems.   Every site requires a site-specific design.
Therefore, the initial point of reference should be any site-characterization/
site-exploration work accomplished, as discussed in Chapter 2.  From the
site's specific characteristics,  an idea can be gained of the demands that the
site will impose on the cover system.  With these demands in mind, the designer
can establish how the cover system must function to produce the desired end
result (watertight or leaky roof;  if leaky,  how much leakage is acceptable).
Then, the cover elements are chosen to fulfill  these functions.   For each
element,  a variety of materials (with their related installation practices)
may be used.   These general methods and materials are evaluated according to
their suitability to perform the  element's required functions under the imposed
conditions, their availability in  the vicinity of the waste site,  and their
cost.  This evaluation will create a list of suitable materials for each cover
element,  ranked relative to one another.   By taking the most suitable material
for each element, a preliminary "preferred"  cover design can be formulated.
This preliminary cover design is  evaluated as to the compatibility of the
different construction operations  involved with each element's selected mate-
rial or materials.   This evaluation will  insure that the construction practices
involved with the installation of  one element will  not adversely affect the
performance of any other cover element.   If a conflict exists that cannot be
resolved by modification of the material  or the construction process, then the
next most suitable material for that element (or elements)  should be evaluated.
The end result of these series of  selections and evaluations is a cover system
whose design, construction, and operational  qualities have  all been taken into
consideration.

    The next section, "Infiltration and Percolation," discusses the water
balance operating at a cover system.   In the sections that  follow, cover
elements are treated in order from the bottom up (cf.  Figure 4-1).   The last

                                      4-5

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                               FIGURE 4-2

GENERAL DECISION  FLOWSHEET  FOR COVER  DESIGN  FORMULATION
                              SITE CHARACTERIZATION
                                   STUDY
                   GENERAL
                   METHODS
                     AND
                   MATERIALS
                      L
                             ESTABLISHMENT OF COVER
                                  FUNCTIONS
COVER
ELEMENT


COVER
ELEMENT


COV6R
ELEMENT
       GENERAL
       METHODS
        AND
      MATERIALS
GENERAL
METHODS
  AND
MATERIALS
                                        S = SUITABILITY

                                        A = AVAILABILITY  Yl

                                        C = COST
FORMULATION OF A PREFERRED
     COVER DESIGN
                               FORMULATION OF FtNAL
                                  COVER DESIGN
                                    4-6

-------
                                                                   FIGURE  4-3

                                                     REVIEW  OF  POTENTIAL  PROBLEMS
    IS SURFACE WATER
   RUN-ON A PROBLEM7X
                                                                                       IS CLIMATE
                                                                               SUITABLE FOR UNIRRIGATED
                                                                                   VEGETATIVE COVER?
       ARE SPECIAL
CONSTRAINTS IMPOSED BY NATURAL
      TOPOGRAPHY?
                                                                                                                    IS  SPRAY
                                                                                                                   IRRIGATION
                                                                                                                 ACCEPTABLE?
   IS TOPOGRAPHY
MODFCATION FEASBLE?
                                                 ACCOMMODATE
                                                   DESIGN TO
                                                    NATURAL
                                                  TOPOGRAPHY
                                                                                                               DESIGN MUST INCLUDE
                                                                                                                  NONVEGETATIVE
                                                                                                              SURFACE STABILIZATION
                                                                                                                 USE VEGETATIVE
                                                                                                                 STABILIZATION
       ARE WASTES   ^	NO
    ABOVE WATER TABLE?
    ARE NATURAL MATERIALS
SUITABLE FOR ALL COVER-SYSTEM
    COMPONENTS LOCALLY
        AVALABLE7
                                                            IS SEVERE
                                                           SUBSIDENCE
                                                             LIKELY?
                                  DESIGN MUST ^CORPORATE
                                     IMPORTED AND/OR
                                    SYNTHETIC MATERIALS
                                                                                                                 CAPABILITY FOR
                                                                                                                 FUTURE REPAIRS

-------
element treated will be the surface water management plan.  In some respects
this is the most critical element in the cover system, because it is surface
water that the whole system is designed to control, and a good surface water
management system minimizes the load placed on other parts of the system.  The
designer should keep the surface water management problem in mind as he designs
the other elements of the cover system.


4.2 Infiltration and Percolation; The Water Balance


    A key step in the design of a hazardous-waste-site cover system is esti-
mating the potential amount of leachate that may be produced.   To make an
enlightened estimate, it is necessary to understand how water may enter the
cover, move through it into the waste cells, and ultimately exit as leachate.
In this section, some of the processes involved in leachate generation are
discussed, and methods for estimating the volumes of leachate that may be
produced are presented.

    This discussion is a more detailed treatment of the subjects mentioned
under "hydrologic cycle" in Chapter 1.  For a clear discussion of the prin-
ciples involved, the reader is referred to Bouwer (1978).


    4.2.1 General Water Movement Patterns in Waste Site Areas
    Water movement patterns in the vicinity of a hazardous-waste disposal site
are governed by the same principles that control subsurface water flow in gen-
eral.  For example, consider the simplified soil/water profile presented in
Figure 4-4.  In the situation depicted, which is typical for most of the land
mass of the earth, subsurface water may be considered to be distributed be-
tween two major regions; the zone of aeration and the zone of saturation.  The
zone of aeration may be further subdivided into the soil-water, intermediate
(vadose), and capillary zones.

    In the saturated zone, all  voids are completely filled with water and,
therefore, the soil moisture content, on a volumetric basis, is equal to the
soil porosity.   However, in the zone of aeration, some of the void space is
filled with air almost all the time.   Exceptions occur as moisture moves
downward from the surface toward the saturated zone;  for example,  following a
period of rain.   The two principal  zones are separated by a phreatic surface,
or water table as it is commonly called (see Figure 4-4).

    Water from precipitation or surface runon (e.g.,  irrigation) may enter  the
top of the soil  column in response  to capillary and gravitational  forces.
This process is called infiltration.   However, once water begins to move
through the soil, the term percolation is used to described its motion.   While
infiltration and percolation are conceptually different, it is difficult to
separate them precisely.
                                      4-8

-------
                                  FIGURE 4-4

                         SIMPLIFIED SOIL/WATER PROFILE

                                        GROUND SURFACE
                  SOIL-WATER
                     ZONE
                 INTERMEDIATE
                    VADOSE
                     ZONE
                   CAPILLARY
                     ZONE
        OK-
                                         WATER TABLE
                                                                \
>!
 Q
                                       IMPERMEABLE
                                         STRATUM
    As water infiltrates into the soil,  it first enters what is  shown on Fig-
ure 4-4 as the soil-water zone.   The thickness of this zone varies  with  soil
type and vegetation, but may generally be considered to extend from the  soil
surface down through the major root zone, that is,  the depth to  which major
roots penetrate.   In agricultural situations,  the root zone may  be  3 to  4 ft
thick, or even greater in some cases.   However,  the design of most  cover sys-
tems limits the root zone considerably.

    If the water content of a soil  is  less than  the field capacity,  water is
held stationary by a combination of capillary  and electrochemical forces, and
drainage (i.e., downward percolation), for the most part, cannot occur.   If
the soil water content exceeds the  field capacity,  water will move  deeper into
the soil column in response to gravitational  forces.   Agronomists generally
                                      4-9

-------
define field capacity as the soil water content in equilibrium with a soil
suction of one-third of an atmosphere.  Soil suction refers to the tension
existing in soil water under unsaturated conditions; it is a complex effect
resulting from capillarity, adsorption, osmosis, etc.

    As long as the water content of a soil exceeds the wilting point, plants
can extract water from the soil.  However, at lower water content, they remain
in a permanently wilted condition.   Agronomists usually define wilting point
as the soil water condition at a soil suction of 15 atmospheres.  The differ-
ence in the actual soil water content (limited by the field capacity) and the
soil water content corresponding to the wilting point is called plant-avaiTable
water because it is available to sustain vegetation.  Soil water  in excess of
the field capacity is called gravitational water, because it may  be expected
to percolate under the influence of gravity.  Soil water content  less than the
wilting point is called unavailable water, because it is tightly  held and can
neither percolate nor be extracted by plants.

    The various relationships among the categories of soil water  described
above are shown graphically in Figure 4-5.  Typical values for porosity, field
capacity, and wilting point, along with other data to be described later, are
presented in Table 4-1.  (See the caution in section 3.2.6 against use of
tabulated property values for design purposes.)  For comparison purposes,

                                  FIGURE 4-5

                       TYPICAL SOIL-WATER RELATIONSHIPS
        0.65
                                                                  7.80
                                       PLANT AVAILABLE WATER
                                    UNAVAILABLE WATER
                  SAND
SANDY
LOAM
                                  LOAM
SILT
LOAM
CLAY
LOAM
                                                        CLAY
                         DECREASING HYDRAULIC CONDUCTIVITY
                                      4-10

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                                        TABLE 4-1
                              TYPICAL SOIL CHARACTERISTICS

Soil
HELPa
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Texture
USDAb
CoS
CoSL
S
FS
LS
LFS
LVFS
SL
FSL
VFSL
L
SIL
SCL
CL
SICL
sc
SIC
c
Class
USCSC
GW
GP
sw
SM
SM
SM
SM
SM
SM
MH
ML
ML
SC
CL
CL
CH
CH
CH
MIRd
In/Hr
0.500
0.450
0.400
0.390
0.380
0.340
0.320
0.300
0.250
0.250
0.200
0.170
0.110
0.090
0.070
0.060
0.020
0.010
Porosity
Vol/Vol
0.351
0.376
0.389
0.371
0.430
0.401
0.421
0.442
0.458
0.511
0.521
0.535
0.453
0.582
0.588
0.572
0.592
0.680
Field
Capacity
Vol/Vol
0.174
0.218
0.199
0.172
0.16
0.129
0.176
0.256
0.223
0.301
0.377
0.421
0.319
0.452
0.504
0.456
0.501
0.607
Wilting
Point
Vol/Vol
0.107
0.131
0.066
0.050
0.060
0.075
0.090
0.133
0.092
0.184
0.221
0.222
0.200
0.325
0.355
0.378
0.378
0.492
Hydraulic6
Conductivity
In/Hr
11.95
7.090
6.620
5.400
2.780
1.000
0.910
0.670
0.550
0.330
0.210
0.110
0.084
0.065
0.041
0.065
0.033
0.022
mm/day
3.3
3.3
3.3
3.3
3.4
3.3
3.4
3.8
4.5
5.0
4.5
5.0
4.7
3.9
4.2
3.6
3.8
3.5
 Soil Classification system used in the HELP model (see discussion in text).
 Soil Classification system used by the U. S. Department of Agriculture.
°The Unified Soil  Classification System.
dMIR = Minimum Infiltration Rate.
eSome hydraulic-conductivity values may appear high for respective USCS classes because
 tilled agricultural soils were considered in HELP model development.
 CON = Evaporation Coefficient.
                                          4-11

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porosity and the various measures of soil water are usually expressed, in
soil-science usage, in volume per volume terms.  For example, if voids account
for 40 percent of the volume of a given soil, the porosity may be reported as
0.4.  Occasionally, it is useful to report soil water values in terms of
inches.   For example, consider a 24-in.-thick layer of soil having a water
content of 0.50 and a field capacity of 0.45, both expressed in volume per
volume terms.   For this case, the total gravitational water in the soil layer
is 1.2 in.   That is,

    total gravitational water = (soil moisture content - field capacity)
                                (layer thickness)

or, total gravitational water = (0.50-0.45) (24) = 1.2 in.

    Depending upon the amount of water that infiltrates, the rate at which
water is removed by plants and evaporation, and the previous soil water con-
tent, water may percolate through the zone of aeration to the saturated zone.
The capillary zone represents a transition from the saturated zone to the zone
of aeration that results because water rises in the smaller (capillary) inter-
connected pores in response to surface-tension effects.   The thickness of the
capillary zone varies inversely with the pore size of the soil, and may range
from only a few millimeters for fine gravel to hundreds  or even thousands of
millimeters for finer-grained soils.

    Within the saturated zone, water movement may generally be described by
Darcy's Law.  One commonly used form is
where
         Q
         A
         V
         K
     dh/dL
the
the
              Q/A = V = -Kdh/dl


volumetric flow rate (L3/T),
gross area through which flow occurs
                                                                         (4.1)
the "Darcy velocity" (L/T),
the hydraulic conductivity (L/T),
the hydraulic gradient (L/L).
(L2),
    The negative sign indicates that water flows in the direction of a de-
creasing hydraulic gradient.   The gross area  A  through which flow occurs is
defined more specifically as the total area, of both pores and solid soil par-
ticles, projected on a plane normal to the direction of flow.   Since water
cannot actually flow through the solids, it is obvious that the "Darcy veloc-
ity" does not represent the actual speed with which flow moves.  The relation
between Darcy or superficial  velocity and actual seepage velocity is discussed
in section 3.2.4.7, "Permeability."

    Darcy's Law was originally developed for slow flow through coarse-grained
soils.  Darcy's Law is widely used in ground-water studies, since most ground-
water flow is laminar.  However, for dense clay soils and low hydraulic gradi-
ents, Darcy's Law may predict more flow than actually occurs.   The principal
reason is that electrochemical interactions between clay particles and water
contained in very small pores result in nonlinearities in the relationship be-
tween flow rate and hydraulic gradient.  Flow rates predicted for clay soils
                                      4-12

-------
and low hydraulic gradients are low anyway,  and  any  deviations due to this
effect are in the direction of even lower flows.   Thus  treatment by Darcy's
Law is conservative from the standpoint of the cover designer.

    Permeability has been discussed at length  in Chapter  3.   Intrinsic permea-
bi1ity is solely a function of the medium through which flow  occurs, while
hydraulic conductivity (or coefficient of permeability) is a  function of both
the medium and the specific fluid, water.   The two measures of permeability
are related as follows:

                              k = (K)  (M)/(P)  (g)                       (4.2)

where
         k = the intrinsic permeability (L2),
         K = the hydraulic conductivity (L/T),
         u = the kinematic viscosity of the  fluid (M/LT),
         p = the density of the fluid  (M/L3),
         g = the gravitational  constant (L/T2)

Both intrinsic permeability and hydraulic conductivity  depend upon physical
factors including porosity and particle size, distribution, shape, and packing
arrangement.   In general, for unconsolidated media,  both  k   and  K  increase
with increasing particle size.   Conversion factors among  common units of
permeability may be found in Table 3-5.

    Most engineering-oriented groundwater-hydrology  textbooks and handbooks
concentrate on flow in the zone of saturation.   It is desirable that a site be
situated well above the  water table, and most hazardous-waste disposal sites
should be so situated that the waste,  and certainly  the cover system, are
within the zone of aeration.   (If the  cover  system is not within the zone of
aeration, the site has severe problems,  among which  cover is  relatively
minor.)  Unsaturated flow is more complex than saturated  flow and is more dif-
ficult to define and describe mathematically.  Much  of  the literature concern-
ing unsaturated flow has been published by soil  scientists, especially those
interested in irrigation and plant uptake of water.

    For sites that are near the water  table  or are subject to flooding,  reme-
dial  measures other than cover will  be  required.

    Darcy's Law can be applied to flow  in the unsaturated zone.   However, dif-
ficulty arises because the unsaturated  hydraulic  conductivity,  K  ,  is  a
function of both the soil moisture content and the soil suction.   In unsatu-
rated flow, part of the  pore space is occupied by air,  thus the area through
which water can flow is  reduced.   As a  result,   K   is  always less than
the corresponding saturated hydraulic conductivity,  K  .  The relationship
between  K  and  K   can be approximated mathematically as:


                                K   /S   - S \3

                                H^-v)                           (4-3)
                                     4-13

-------
where
         Ku = the unsaturated hydraulic conductivity (L/T),
          K = the saturated hydraulic conductivity (L/T),
         S  = the actual degree of saturation (L3/L3),
         S  = the threshold degree of saturation (L3/L3), (that is, that
              fraction of pore space occupied by nonmoving water held in
              place by capillary forces).

This relationship may be seen graphically in Figure 3-14.


    4.2.2 Cover as a Leaky Roof


    The principal objective of placing a cover system over a hazardous-waste
disposal site is to limit the amount of leachate that will be produced as
water infiltrates and percolates downward through the site.   In this discus-
sion, any water that contacts the wastes is considered to be leachate.   How-
ever, unless an impermeable (usually synthetic) membrane is used,  the cover
system will  not be completely impermeable.   Therefore, the cover system may be
thought of as a sort of "leaky roof" over the disposal area.   A typical  three-
layer system is shown schematically in Figure 4-6.   The flow predictions that
form the rest of this section are based on this general leaky-roof model.

    From a conceptual viewpoint, it is rather easy to write a mass balance for
the flow of water onto, across,  and through a cover system.   Such  a statement
is often called a water balance.   The major components of the water balance
for a hazardous waste site cover are presented on Figure 4-6.   As  shown,
precipitation falling on the site may be partitioned among runoff, infiltra-
tion, and surface evaporation (a component of evapotranspiration).   Surface
runon is not considered herein because good design practice calls  for surface
grading to prevent its occurrence.   For the system illustrated, water that
infiltrates  the cover may be further partitioned among soil  evaporation and
plant transpiration (both are components of evapotranspiration), lateral
drainage, soil  moisture storage, and percolation downward out of the cover.
This last component enters the waste cells and, thus, represents eventual
leachate production.   That is, this water is unlikely to be removed by any
process other than continued percolation through the waste cells.   For a par-
ticular site, the fate of water that infiltrates is controlled primarily by
the soil moisture content.   Other factors such as temperature, vegetation
type, the vegetative growth cycle,  etc. , are also important.   Unfortunately,
actually constructing a detailed water balance is more difficult than grasping
the concept, since some of the components are difficult to quantify.  Never-
theless, virtually all methods of estimating potential leachate production
depend upon water-balance calculations.


    4.2.3 Precipitation


    Since cover systems for hazardous-waste disposal sites are normally lo-
cated well above the local ground-water table and are graded so as virtually

                                      4-14

-------
                                 FIGURE 4-6

                      SCHEMATIC THREE-LAYER COVER SYSTEM

                     PRECIPITATION         EVAPOTRANSPIRATION

                                 VEGETATION        j   RUNOFF
                                                   in11
                              I
                              t
                         INFILTRATION
                                             I
D VEGETATIVE  LAYER

  §   (2)  LATERAL DRAINAGE  LAYER        LATERAL  DRAINAGE
  CO	___—       (FROM  COVER)

  UJ
  o:   ®  BARRIER  SOIL  LAYER
  13                                               PERCOLATION
                                            (FROM BASE OF COVER)
                                                        i
                                                        i
                                                        i
                                                        Y
          WASTE  LAYER
to eliminate surface runon, precipitation  falling directly onto the  site  is
the principal  source of moisture for any infiltration and percolation  that may
occur.   While  precipitation may occur in several forms, only rain and  snow are
considered.   Rain  is by far the most important for most locations in the
temperate zone.

    Because  of the relatively small  size of  hazardous-waste disposal areas,
the complicated techniques often used to generate weighted-average precipita-
tion data for  larger watersheds are  generally not needed.   Therefore,  in  most
cases,  historical data for a nearby  location will be satisfactory.   However,
it may  also  be of interest to consider hypothetical data corresponding to wet
periods having known return periods.

    Snowmelt may be estimated by a variety of methods (Chow, 1964).  For
example,  the expression shown below  (Soil Conservation Service,  1974) may be
used to estimate the maximum snowmelt that may occur on a given day.


                             SM = 0.06 (T - 32)                         (4.4)

                                     4-15

-------
where
         SM = the maximum snowmelt for the day (inches of water),
          T = the mean air temperature for the day (°F).

The above expression may be used to estimate the actual snowmelt only when
T > 32°F  (otherwise melting is assumed not to occur) and when the total accu-
mulated snowpack is equivalent to (or greater than) 0.06 (T - 32) inches of
water (otherwise all accumulated snow is assumed to melt).   Snowmelt may be
partitioned into runoff and infiltration using the same techniques discussed
for rainfall in a subsequent section.


    4.2.4 Runoff
         4.2.4.1 General
    As indicated on Figure 4-6 and discussed above, infiltration and runoff
are important and closely related components of the water balance.   In fact,
it is not possible to estimate either one without at least an implicit con-
sideration of the other.  In this section, some methods that may be used to
estimate runoff (and hence infiltration) from precipitation data are briefly
discussed.   A somewhat more detailed discussion of the actual process of
infiltration, and the various factors that influence it, is presented below.

    It is reasonable to view hazardous-waste disposal sites as very small
watersheds.   As rain falls (or snow melts) on such an area, some is inter-
cepted by vegetative (or other) surfaces that may be present, and,  assuming
that the infiltration capacity is exceeded, puddles form in surface depres-
sions.  The scale of these depressions may vary over a wide range depending
upon the nature of the cover-system surface.  If precipitation (or snowmelt)
continues long and hard enough, the capacity of surface depressions is ex-
ceeded and runoff begins.  In the typical case, this runoff is directed to a
surface drainage system and conveyed away from the site.

    Selection of the runoff-estimation method best suited for a given applica-
tion is influenced by a number of factors.  These include the size and nature
of the watershed; the precision required; the amount, quality, and type of
data available; and the use that is to be made of the estimate.  For example,
to determine whether the yield of a watershed is sufficient to meet the long-
term water-supply needs of a municipality, an estimate of the average annual
runoff may be sufficient.  On the other hand, to size a culvert, it is neces-
sary to know the peak rate at which runoff will be produced for the design
storm event.  For hazardous-waste-site cover systems, both average and peak
runoff rates may be important.

    Runoff-estimation methods for design of cover systems should be applicable
to very small watersheds, be relatively simple and straightforward to use, and
have minimal data requirements.  The data requirement is especially important
since it is obvious that detailed rainfall/runoff data cannot possibly exist
                                      4-16

-------
for cover systems yet to be designed and built.   Two conventional  runoff-
estimation methods that more or less meet these criteria are discussed below.
         4.2.4.2 Runoff Coefficients
    Runoff can be estimated directly from precipitation data if reliable run-
off coefficients are available.   The best-known runoff-coefficient technique
is the so-called rational method.   It is presented here because,  for very
small watersheds, it can be used with reasonable accuracy even when little
site-specific data is available.
         4.2.4.3 The Rational Method
    The basic mathematical expression for the rational  method is

                                Q = (C) (I) (A)
                                  (4.5)
where
         Q = the runoff volume (cubic feet per second),
         C = the runoff coefficient (assumed dimensionless),
         I = the average rainfall intensity (inches per hour),
         A = the watershed area (acres).

The runoff coefficient is considered dimensionless because 1  acre-inch per
hour is equal to 1.008 cubic feet per second.   The principal  use of the ra-
tional  method is estimation of peak runoff rates for small watersheds (smaller
than one square mile), especially for culvert and storm-sewer design.

    The basic premise of the rational method is that the peak runoff result-
ing from steady, uniformly intense precipitation will occur when the entire
watershed upstream of the design location just begins to contribute to the
flow.   This condition is met at some elapsed time, t  , after precipitation
begins; t   is called the time of concentration.  It is usually assumed to
equal  thectime for water to flow from the most distant point in the watershed
to the design location and is normally estimated from consideration of the
hydraulic characteristics of the watershed.  One expression that has been
suggested (Kirpich, 1940) for small agricultural watersheds is
                           t  -.(LA.
1Q-3)(L)°-77
                                      -0.385
                                  (4.6)
where
         t  = time of concentration (minutes),
          L = distance from design location to furthest point in watershed
              (feet),
          S = average slope of watershed along distance  L  (dimensionless).
                                      4-17

-------
    Once the time of concentration is known, an average rainfall intensity can
be selected and the peak runoff rate can be estimated.  Rainfall intensity-
duration-frequency curves developed for various areas of the country (U. S.
Weather Bureau, 1955) are generally used to estimate the average rainfall
intensity.  Guidance for selection of runoff coefficients is presented  in many
textbooks and handbooks.  Typical values are shown in Tables 4-2 and 4-3.  The
values presented in Table 4-2 are most directly applicable to storms with 5-
to 10-year recurrence intervals.  A principal criticism of the rational method
as it is commonly used  is that the runoff coefficient is assumed to be  con-
stant, while it actually varies with both infiltration and precipitation.  To
circumvent this problem to some extent, runoff coefficients may be adjusted
downwards to account for the effects of more frequent storms or storms  occur-
ring after long dry periods, and may be adjusted upwards for less frequent
storms or storms occurring during prolonged wet periods.  Excellent discussions
of the rational method are presented by Chow (1964), Viessman et al.  (1977),
and Schaake, Geyer, and Knapp (1967).   The Federal Aviation Agency (1970) has
presented graphical procedures for estimating overland flow times.

    The rational method as described above may be used directly to estimate
peak runoff and, thus, make it possible to size runoff control  features, such
as inlets, catch basins, open channels, detention basins,  and drainage  pipes,
for a storm of any desired recurrence interval.   However,  runoff coefficients
may also be used to estimate daily, weekly,  monthly, etc., runoff from  corre-
sponding precipitation data.   For example, consider the expression shown
below.

                                  R = (C) (P)                            (4.7)

where
         R = total  runoff for the period considered in same units as
             precipitation,
         C = dimensionless runoff coefficient,
         P = total  precipitation for the period considered in same units as
             runoff,

Obviously, this expression suffers from the  same limitations as the rational
method.   However,  it may be used to predict  runoff with sufficient accuracy to
construct, for example,  a monthly water balance, if care is used in adjusting
the runoff coefficient to account for the relatively smaller fraction of
precipitation that will  run off during relatively dry periods,  or in  response
to low-intensity rainfall (that is, it may be reasonable to assume that only
precipitation in excess of some given amount will run off).

    Other methods  utilizing runoff coefficients are discussed by Linsley and
Frazini  (1979), Chow (1964), Lisley, Kohler, and Paulhus (1958), and  Viessman
et al.  (1977).   Synthetic-hydrograph methods are very popular and may be used
to predict runoff from specific storms.  However, since their use is  usually
not justified for very small homogeneous watersheds such as cover systems,
they are not discussed here.
                                      4-18

-------
                                   TABLE 4-2
                          TYPICAL RUNOFF COEFFICIENTS
  Description of Area
                                                                     Runoff
                                                                  Coefficients
Business
   Downtown areas
   Neighborhood areas
Residential
   Single-family areas
   Multiunits, detached
   Multiunits, attached
Residential (suburban)
Apartment dwelling areas
Industrial
   Light areas
   Heavy areas
Parks, cemeteries
Playgrounds
Railroad yard areas
Unimproved areas
Streets
   Asphaltic
   Concrete
   Brick
Drives and walks
Roofs
Lawns; Sandy Soil:
   Flat, 2%
   Average, 2-7%
   Steep, 7%
Lawns; Heavy Soil:
   Flat, 2%
   Average, 2-7%
   Steep, 7%
0.70-0.95
0.50-0.70
0.30-0.50
0.40-0.60
0.60-0.75
0.25-0.40
0.50-0.70

0.50-0.80
0.60-0.90
0.10-0.25
0.20-0.35
0.20-0.40
0.10-0.30

0.70-0.95
0.80-0.95
0.70-0.85
0.75-0.85
0.75-0.95
0.05-0.10
0.10-0.15
0.15-0.20
0.13-0.17
0.18-0.22
0.25-0.35
From American Society of Civil Engineers (1969)
                                      4-19

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                                   TABLE 4-3

                  RUNOFF COEFFICIENTS FOR AGRICULTURAL LANDS
                                                    Watershed cover
              Soil type                   Cultivated     Pasture     Woodlands
With above-average infiltration rates;
usually sandy or gravelly
With average infiltration rates; no
clay pans; loams and similar soils
With below-average infiltration rates;
0.20
0.40
0.50
0.15
0.35
0.45
0.10
0.30
0.40
  heavy clay soils or soils with a
  clay pan near the surface; shallow
  soils above impervious rock
         4.2.4.4 The SCS Curve Number Method
    The United States Soil Conservation Service (SCS) must frequently make
runoff estimates for small watersheds where little or no precipitation/runoff
data are available, but soil types, topography, vegetative cover, agricultural
practices, etc., are fairly well defined.   Over the years, this agency has
developed a runoff-estimation technique for this kind of situation that is
generally known as the SCS curve-number method.  This technique is well suited
to estimating runoff from cover systems.   A companion method, also developed
by the SCS, may be used to synthesize a hydrograph for a design storm, if such
is desirable (Soil Conservation Service,  1974).

    The SCS curve-number method is based upon the following empirical
expression.

                              0 _ [P - (Q.2)(S)]2                        (4 8)
                              g    P + (0.8)(S)                          l   ;

where
         Q = runoff for the time period considered (L),
         P = precipitation for the time period considered (L),
         S = the potential retention (L).

The retention parameter, S , may be thought of as the potential infiltration
when precipitation begins.  It is a function of the hydrologic properties of
the soil and vegetation.  S  is considered to be a constant for a given storm.
The so-called "curve number," CN , is actually merely a transformation of  S
selected to make plotting easier, and has no other physical significance.  The
relationship between  S  and  CN  is given by

                                      4-20

-------
                                  CN =  100°                             (4 9)
                                  LIN   S + 10                            ^   ;

where
         CN = the curve number (dimensionless),
          S = the potential retention (inches).

By combining equations (4.8) and (4.9), it is possible to estimate runoff
directly from rainfall if the appropriate value of  CN  can be established.

    Data from many small watersheds suggests the following empirical relation-
ship, which is implicit in equation (4.8).

                                 I  = 0.2 (S)                           (4.10)
                                  3

where
         I  = the initial abstraction, i.e., all rainfall that occurs before
              runoff begins (L).

    The potential retention, S  (and thus the curve number), is related to the
soil moisture content when rainfall begins.   For convenience, SCS has defined
three general antecedent moisture conditions:  I, II, and III.   These are de-
fined as follows, in terms of the total 5-day antecedent rainfall  PA5  (Soil
Conservation Service, 1974):  condition I,   PA5 < 1.4 in. (growing season) or
< 0.5 in.  (dormant season);  condition II,   PA5  1.4 - 2.1 in.  (growing sea-
son) or 0.5-1.1 in.  (dormant season); condition III,  PA5 > 2.1 in.  (growing
season) or > 1.1 in.  (dormant season).  Antecedent moisture condition I repre-
sents generally dry conditions (soil moisture content above the wilting point,
however) such that the soil may be plowed or cultivated satisfactorily; condi-
tion II represents "average" conditions; and condition III represents very wet
(i.e., essentially saturated) soil conditions.

    S  (and also  CN ) is also a function of the hydrologic properties of the
soil(s) at the site.   For convenience, soils are classified as belonging to
hydrologic group A,  B, C, or D.   The characteristics of each group are summa-
rized in Table 4-4.   Major soils of the United States and Puerto Rico have
been classified by hydrologic soil group.   Extensive lists are presented by
Chow (1964) and the Soil Conservation Service (1974).

    Another factor that affects  S  and  CN  is referred to as the "cover."
In this context, the term "cover" is used to describe any material (usually
vegetation) that covers the soil  and provides protection from the impact of
rainfall.   The hydrologic condition of the  cover is especially important and
is generally described as poor,  fair, or good.   Poor conditions result from
row crops, small grains, and fallow conditions.   Good conditions arise from
vegetative covers such as close-seeded legumes or grasses that enhance infil-
tration capacity.  Detailed guidance for describing hydrologic condition is
presented by the SCS (1974) and Chow (1964).

    Two final factors that affect  S  and  CN  are land treatment practice and
land use.   Since the method was originally  developed for agricultural areas,
land treatment practices such as straight row or contour plowing and terracing

                                      4-21

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                                        TABLE 4-4

                      CLASSIFICATION OF SOILS BY HYDROLOGIC CHARACTERISTICS
Hydrologic
Soil Group
Rate of Water
Transmission
  Rate of
Infiltration
  Runoff
Potential
General Description
    A     High


    B     Moderate



    C     Slow



    D     Very Slow
             High         Low         Consisting chiefly of deep,  well  to excessively
                                     drained sands or gravels.

             Moderate      Intermediate  Consisting chiefly of moderately  deep to deep,
                                     moderately well to well drained soils with moder-
                                     ately fine to moderately coarse textures.

             Slow         Intermediate  Consisting chiefly of soils  with  a layer that
                                     impedes downward movement of water, or soils with
                                     moderately fine to fine texture.

             Very Slow     High         Consisting chiefly of clay soils  with a high
                                     swelling potential, soils with a  permanent high
                                     water table, soils with a claypan or clay layer
                                     at or near the surface, and  shallow soils over
                                     nearly impervious material.
 When thoroughly wetted.


 are  usually considered.   Land  use is generally defined  with respect  to the
 type  of vegetation  that predominates.

      Curve numbers representative  of various  combinations  of hydrologic soil
 group,  hydrologic condition of the cover,  land use, and land treatment practice
 are  presented in Table 4-5.  The  values shown are for antecedent soil  moisture
 condition II, and assume that  initial abstraction is adequately estimated by
 equation (4.10).  Curve numbers appropriate  for any antecedent moisture condi-
 tion  can be estimated from Table  4-6, if the curve number for any other ante-
 cedent  moisture condition is known.   The relationship between rainfall and
 runoff  for various  values of   CN   is shown on Figure 4-7.   To use this figure
 to estimate runoff,  one merely enters along  the abscissa  with the total amount
 of precipitation for the time  period, reads  up to the appropriate curve,  and
 over  to the estimated runoff on the ordinate.
     4.2.5 Infiltration
           4.2.5.1 General
      Infiltration  is  the process  by which water enters  at  the surface  of a soil
 column.   Any cover  system other  than one with a rather impervious member at
 the  ground surface  (comparable to an asphalt-surfaced  parking lot)  will expe-
 rience  infiltration.   Whether the infiltrated water goes  on to produce
 percolation depends  on the design of the cover system,  and particularly on the
 impervious-barrier  member.   Infiltration is  a key component in any  water-
 balance analysis.   Thus it is important for  the cover  system designer to have
 an appreciation for  the nature of the infiltration process, the factors that
                                          4-22

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                                  TABLE 4-5


          RUNOFF CURVE NUMBERS FOR ANTECEDENT MOISTURE CONDITION II

                          (ASSUMING I  = (C
                                     3

Land Use
Fa How
Row crops







Small grain







Close-seeded
Legumes3 or
rotation
meadow




Pasture or
range




Meadow
Woods


Farmsteads
Roads (dirt)
(hard surface)
Cover
Treatment
or Practice
Straight row
Straight row
Straight row
Contoured
Contoured
Contoured and
terraced
Contoured and
terraced
Straight row
Straight row
Contoured
Contoured
Contoured and
terraced
Contoured and
terraced
Straight row
Straight row
Contoured
Contoured
Contoured and
terraced
Contoured and
terraced



Contoured
Contoured
Contoured







Hydro! ogic
Condition
--
Poor
Good
Poor
Good
Poor

Good

Poor
Good
Poor
Good
Poor

Good

Poor
Good
Poor
Good
Poor

Good

Poor
Fair
Good
Poor
Fair
Good
Good
Poor
Fair
Good
--
--
—
Hydro logic
A
77
72
67
70
65
66

62

65
63
63
61
61

59

66
58
64
55
63

51

68
49
39
47
25
6
30
45
36
25
59
72
74
B
86
81
78
79
75
74

71

76
75
74
73
72

70

77
72
75
69
73

67

79
69
61
67
59
35
58
66
60
55
74
82
84
Soil Group
C
91
88
85
84
82
80

78

84
83
82
81
79

78

85
81
83
78
80

76

86
79
74
81
75
70
71
77
73
70
82
87
90
D
94
91
89
88
86
82

81

88
87
85
84
82

81

89
85
85
83
83

80

89
84
80
88
83
79
78
83
79
77
86
89
92

Close-drilled or broadcast.
Including right-of-way.
                                     4-23

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                     TABLE 4-6

CORRESPONDING CURVE NUMBERS FOR ANTECEDENT MOISTURE
             CONDITIONS I, II, AND III
                   CURVE NUMBERS
        FOR ANTECEDENT MOISTURE CONDITIONS
                         II
                    FIGURE 4-7

 RUNOFF VS.  RAINFALL FOR VARIOUS SCS CURVE NUMBERS
   (CHOW, 1964; SOIL CONSERVATION SERVICE, 1974)
                         10  12   14
                     STORM RAINFALL, IN.
III
TOO
87
78
70
63
57
51
45
40
35
31
26
22
18
15
12
9
6
4
2
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
100
98
96
94
91
88
85
82
78
74
70
65
60
55
50
43
27
30
22
13

                        4-24

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affect infiltration, and how the amount of water that will infiltrate under
various design configurations can be estimated.  Each of these topics is
considered in the following discussion.

    Over the past several years the infiltration process has been the subject
of a considerable amount of both theoretical and applied research.  Unfortu-
nately, the process is so complex, and is influenced by so many factors, that
no universally acceptable means of describing infiltration has yet been
developed.  The principal thrust of theoretical research has been to formulate
partial differential equations for saturated and unsaturated flow through
porous media and to develop general solutions for these equations.  On the
other hand, much research effort has been expended in observing the actual
infiltration process under various conditions, and then attempting to describe
it by means of specific empirical relationships.  At present, it would appear
that empirical descriptions are more suitable for estimating infiltration at
hazardous waste disposal sites than are the potentially more rigorous
theoretical approaches.  However, in most cases, the use of an indirect means
is the best approach to estimating infiltration.  That is, infiltration can be
estimated simply as the difference between the amount of water available at the
surface of a soil column (the sum of precipitation, snowmelt and runon) and
the sum of the amounts that run off and are lost via surface evaporation.


         4.2.5.2 Infiltration Velocity, Infiltration Capacity, and
                 Infiltration Rate
    The infiltration velocity is the time rate at which water actually enters
at the surface of a soil column at any given time.   The infiltration rate,
also called the infiltration capacity, is the maximum rate at which infiltra-
tion can occur in a given situation under specified conditions.   The equi1ib-
rium infiltration capacity is the infiltration capacity that can be sustained
over a long period of time during which the infiltration velocity is not
limited by the supply of water available at the surface of the soil column.
The infiltration capacity of a given soil can and does vary with time during a
given storm, as discussed below.


         4.2.5.3 Factors Affecting Infiltration


    The infiltration velocity is controlled or limited in one of three ways.
First, of course, it cannot exceed the rate at which water is supplied to  the
surface of the soil column.   Second, it cannot exceed the rate at which water
can enter the soil column.   Finally, it cannot exceed the rate at which water
can percolate through the soil column.  Thus, any factors that affect the
supply rate, the entry rate, or the percolation rate may affect the overall
infiltration process.

    Partitioning between infiltration and runoff is influenced strongly by  the
nature of the soil, and importantly also by the slope of the surface and the
nature and quality of the vegetative cover.   Infiltration is promoted by

                                      4-25

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coarse-grained soil, by flat ground,  and by a well-developed vegetative
covering.   Runoff is promoted by fine-grained soil,  by sloping ground, and by
absence or sparsity of vegetation.   It would seem desirable to minimize perco-
lation in advance by minimizing infiltration and maximizing runoff,  and indeed,
with qualifications, this is true.   However, the conditions that favor runoff
also promote erosion, which is a threat to the cover once constructed and
which must itself be minimized and controlled.   Cover design, thus,  largely
involves trade-offs, of which control of infiltration versus control of erosion
is one of the most important.

    During part of the year at northern sites, the ground is frozen.  During
this period there is little or no infiltration.   Either precipitation falls as
snow, in which case the water remains above the ground surface until the time
of thaw, or should temperatures warm to the point of permitting rain, as the
water infiltrates, it will exchange heat with the ice dispersed in the soil
and either the infiltrated water will freeze or the soil ice will  thaw.  If
the former, percolation will be delayed; if the latter, percolation will
proceed.  Quite different processes may take place,  as temperatures vary
within a narrow range.


         4.2.5.4 Modeling the Infiltration Process


    The infiltration process was studied in detail by Morton (1933, 1939)
during the 1930's.  He suggested the expression shown below, which has served
as the basis for the work of many other researchers.

                            f = fc + (fo - fc)e"kt                      (4.11)

where
          f = the infiltration capacity (L/T) at a given time, t (T),
         fc = the equilibrium infiltration capacity (L/T),
         f0 = the initial infiltration capacity (L/T),
          k = a decay constant indicating that infiltration capacity decreases
              with time during a precipitation event (L/T).

This empirically derived expression  reflects numerous observations  that, for
most soils, infiltration capacity decreases exponentially with time, so long
as water is supplied  to the soil surface at a rate exceeding the equilibrium
infiltration capacity.  A definition sketch corresponding to equation  (4.11)
is presented on Figure 4-8.  The curves shown on Figure 4-9 are, however,
somewhat more indicative of what usually happens.  Curve number 1 represents  a
situation in which the soil profile  is never saturated  because the  rate at
which water is  supplied to  the surface is always less than the equilibrium
infiltration capacity.   If  such a case no runoff occurs.  Curves 2,  3,  and 4
represent responses  to increasing rates of  supply, all  of which exceed  the
equilibrium infiltration capacity.   In each case there  is a period  during
which virtually all  the water supplied to the surface  infiltrates.   However,
once the soil surface  is  saturated (indicated by  ts§Lt  ) the  infiltration  rate
decreases gradually  until  it  approaches the equilibrium infiltration  capacity.


                                      4-26

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                  FIGURE 4-8

  IDEALIZED RELATIONSHIP BETWEEN INFILTRATION
               CAPACITY AND TIME
                       TIME
                  FIGURE 4-9

RELATIONSHIP BETWEEN INFILTRATION RATE AND TIME
       FOR VARIOUS RATES OF WATER SUPPLY
                     TIME
                      4-27

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    In theory, equation (4.11) may be used to describe infiltration only after
the soil surface becomes saturated and so long as the surface water supply
rate exceeds the equilibrium infiltration capacity.   These limitations may be
circumvented by considering the infiltration rate to be a function of soil
moisture content rather than time.   For example,  Holtan (1961) and Overton
(1964) have suggested the following expression.
                              f = f  +
                         A (S - F)'
where
          f =

         fc =
          ^ 	
          F
          A
          P
infiltration capacity,
equilibrium infiltration capacity,
available soil  moisture storage capacity (i.e.
antecedent soil moisture content),
total water infiltrated,
a numerical coefficient,
a numerical exponent.
(4.12)
                                                              porosity minus
Muggins and Monke (1970) have suggested the following rearrangement of equa-
tion (4.12).   In this form dimensional consistency is maintained and  A  and
P  are subject to physical interpretation.
where
         T  —.

          P ~
                              f = f  + A
total soil porosity (L),
                                          S - F
                                            P  J
                                                          (4.13)
and other variables are defined as above.   With this arrangement,  A  may be
seen to have the same units as  f  and  f  ,  and may be interpreted as the
maximum potential increase in the infiltration capacity above the equilibrium
value.   P ,  which is dimensionless,  is related to the rate of decrease of
infiltration capacity with increasing soil moisture content.   Because the
value in the brackets cannot exceed unity, larger values of  P  must be asso-
ciated with more rapid rates of decrease in infiltration capacity.

    Equation (4.13) can be used only if  S ,  F ,  and  T   are determined for a
layer of soil having a definite thickness, usually called the control depth.
The control  depth may be either the depth to a soil layer that significantly
impedes percolation (i.e., controls the percolation rate), or the depth at
which the hydraulic gradient approaches unity.   Even though it may be difficult
to select a suitable control depth,  an expression such as equation (4.13) is
preferable to one like equation (4.11) because it is applicable even when the
surface water supply rate is less than the equilibrium infiltration capacity.
Thus, equation (4.13) can be used to predict the recovery of infiltration
capacity that occurs during such periods.

    Holtan et al. (1975) have presented a somewhat different form of equa-
tion 12 that expresses infiltration capacity as a function of predictable
factors.
                           f = fc + (GI) (a) (S)
                                                1.4
                                                          (4.14)
                                      4-28

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where
          f = infiltration capacity (inches/hour),
         f  = equilibrium infiltration capacity (inches/hour),
         GI = vegetation growth index (percent of plant maturity),
          a = vegetation parameter related to surface-connected porosity and
              plant root density (inch/inchl 4),
          S = available soil moisture storage (inches).

Specific values for  GI  and  a  for various types of vegetation are presented
in Holtan et al. (1975).  Typical ranges for  f   are 0.3 to 0.45, 0.15 to
0.30, 0.05 to 0.15, and 0 to 0.05 inches/hour for hydrologic soil types A, B,
C, and D, respectively (see Table 4-4).

    A number of infiltration models have been developed by assuming that a
distinct boundary (wetting front) moves through the soil column as infiltra-
tion and percolation occur.   The wetting front concept is illustrated on
Figure 4-10.   If the surface water supply is represented by a pool of water of
negligible depth, Darcy's Law may be applied to yield an expression such as
that shown below.
                                f = K,
                                        L + S
(4.15)
where
          f = infiltration capacity (L/T),
         KS = saturated hydraulic conductivity (L/T),
          L = distance from soil surface to the wetting front (L),
          S = capillary suction at the wetting front (L).

                                  FIGURE 4-10

                      SOIL PROFILE AS INFILTRATION OCCURS
                                   WET SOIL
             WETTING  FRONT
                                   DRY SOIL
                                      4-29

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This expression, reported by Green and Ampt (1911),  has served as the basis
for several infiltration models which have appeared  in the literature in
recent years.   The principal difficulty with such a  model  is predicting the
capillary suction.

    The American Society of Civil Engineers (1949) has presented a simple
empirical technique for estimating infiltration.   The key to the method is the
infiltration capacity one hour after excess precipitation (i.e., precipitation
at a rate greater than the equilibrium infiltration  capacity) begins.  This
infiltration rate,  given the symbol  fa ,  may or may not be a good estimator
of  f  .   Typical values of  ^  for three classifications of bare soil are
shown in Table 4-7.  For vegetated soils,  the values in Table 4-7 should be
multiplied by the vegetation cover factors presented in Table 4-8.
                                   TABLE 4-7
                       TYPICAL f1 VALUES FOR BARE SOILS

Soil Classification
Sands and other soils with open structures
Loams typical of better agricultural regions
Clays and other soils with dense structures
1 (inches/hour)
0.50 -
0.10 -
0.01 -
1.00
0.50
0.10

From American Society of Civil Engineers (1949)
                                   TABLE 4-8

                           VEGETATION COVER FACTORS

Vegetation Type
Permanent forest and grass


Close-growing crops


Row crops


Cover Quality
Good
Medium
Poor
Good
Medium
Poor
Good
Medium
Poor
Cover
3.0 -
2.0 -
1.2 -
2.5 -
1.2 -
1.1 -
1.3 -
1.1 -
1.0 -
Factor
7.5
3.0
1.4
3.0
2.0
1.3
1.5
1.3
1.1
From American Society of Civil Engineers (1949)

                                      4-30

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         4.2.5.5 Measurement of Infiltration
    The measurement of infiltration in the field is discussed by Bertrand
(1965).  Infiltration rates, capacities, coefficients, etc., can be estimated
for specific existing sites from data gathered during various types of field
investigations.  For example, infiltrometer studies employing rainfall simula-
tors or small area flooding techniques can be used to determine in situ infil-
tration rates.  Unfortunately, different experimental procedures may result in
substantially different estimates for the same site.

    Infiltration can also be estimated indirectly from precipitation data and
runoff hydrographs.  However, in most cases, hydrographs that distinguish
overland flow from interflow (lateral flow of perched water) are not available.
Thus infiltration volumes determined by this method are usually less than what
actually occurs.


         4.2.5.6 Design Implications


    Many of the factors that influence infiltration are not subject to control
by designers and builders of hazardous-waste-site cover systems.  However,
notable exceptions include soil  type, vegetation type, surface slope, runon
control, etc.  Unfortunately, trade-offs among these controllable factors
complicate the design process considerably.   For example, dense bare soils
placed on steep slopes will initially impede infiltration, but are subject to
severe erosion problems.   On the other hand, a good grass cover on a loamy
soil will effectively control erosion, but will  retard runoff and promote
infiltration.  However, the grass will also serve to remove water from the
cover system via transpiration.   Thus, it should be clear that designing and
evaluating cover systems  are complex processes that require careful considera-
tion of many competing factors.

    The foregoing discussion emphasizes the importance of choosing a compre-
hensive design and evaluation procedure that allows one to predict cover
system performance from data of  the type available during the design phase of
a project.   Two such procedures  are presented in the  section on methods of
water-balance analysis.

    Another important practical  item is the way  infiltration rate varies with
time.   Referring to Figures 4-8  and 4-9, note that as a rainstorm continues,
infiltration rate dec!ines to a  certain level and then remains there, regard-
less of the duration or intensity of the storm.   Any excess water delivered by
a long or hard rain does  not infiltrate but leaves the system as runoff.   It
does not affect the internal structure of the cover but only the surface-water
collection and drainage system.   Thus the latter, but only the latter, must be
designed with emergency flow rates  in mind.
                                      4-31

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    4.2.6 Evapotranspiration


    Evapotranspiration is the principal  means by which soil  moisture is removed
from vegetated soil.   The process is quite complex,  and the  nomenclature used
in describing it can be confusing.   Therefore, brief definitions of some of
the more commonly used terms are presented below.   Evapotranspiration proceeds
rapidly with high temperatures,  direct sunlight, strong winds,  and a dry
atmosphere.   Active evapotranspiration correlates,  thus, with the spring and
summer portion of the annual cycle  and,  on a smaller scale,  with the daytime
portion of the diurnal cycle.   Certain regions regularly experience very windy
seasons; evapotranspiration proceeds actively during such times.   Along with
timewise variations,  there are local geographic variations also:   evapotran-
spiration is more active (in the northern hemisphere) on south-facing than on
north-facing slopes.   An excellent  discussion of evapotranspiration is pre-
sented by Chow (1964).


         4.2.6.1 Basic Principles and Nomenclature


    Evaporation is the process by which  water is converted from the liquid
into the gaseous state through the  transfer of heat energy.   The term soi1
evaporation is used to describe  the evaporation of  water that has infiltrated
into the soil, and the term surface evaporation to  describe  the evaporation of
water from pools, depressions, or plant  or soil surfaces.

    Transpiration is the process by which water that has been absorbed from
the soil by plants is released to the atmosphere.   The vast  majority of the
total water transpired escapes through small openings (called stomata) in the
leaves.  Evapotranspiration is a collective term used to denote the combination
of evaporation and transpiration.  For a hazardous-waste disposal-site cover
system, evapotranspiration may be considered to be  the sum of surface and soil
evaporation and plant transpiration.  Of these three components, transpiration
is almost always much more important quantitatively than the other two.

    Consumptive use is a term used frequently by agronomists and others inter-
ested in agricultural production.  Usually, it represents the sum of all the
water absorbed by plants (whether incorporated into cellular material or
transpired) plus that evaporated from plant, soil,  or snow surfaces, or from
surface depressions.   Thus, the terms evapotranspiration and consumptive use
are often used interchangeably.

    Pan evaporation is defined as the amount of water evaporated from a stand-
ard container, called a pan, under ambient climatological conditions.  The
U. S. Weather Service uses what is called class A standard pan.  The class A
standard pan is made of unpainted galvanized iron,  is 4 ft in diameter, 10 in.
deep, and is suspended 6 in. above the surface of the ground on a wooden
frame.  The water level in the pan is kept at 2 to  3 in. below the rim and is
measured each day by means of a hook gauge.  The Weather Service collects pan
evaporation data routinely at numerous sites, as do other agencies.  Summary
data are widely available in hydrology textbooks and are presented in the

                                      4-32

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Climatic Atlas of the United States (National Oceanic and Atmospheric Admini-
stration, 1974).  Historical data for specific locations are available from
the National Climatic Center as well as agricultural and climatologic research
facilities.

    Potential evapotranspiration is defined as the evapotranspiration that may
be expected so long as the supply of soil moisture to plants is essentially
unrestricted.  However, the rate at which evapotranspiration can actually
occur is severely limited when soil moisture content drops much below field
capacity, because plants have increasing difficulty in obtaining water.   Thus,
actual evapotranspiration, that is, the amount of water actually transpired
and evaporated under the existing conditions, cannot exceed potential
evapotranspiration.

    As a rule, evapotranspiration at a given location exhibits a cyclical
pattern having an annual period.   While several factors may be important, this
pattern is influenced most dramatically by the growth cycle of the vegetation.
Thus, the lowest evapotranspiration rates generally occur in the winter when
the growth rate is nil, and the highest rates occur during the summer at the
peak of the growing season.
         4.2.6.2 Estimating Evapotranspiration
    Surface-water hydro!ogists have given much attention to estimating evapo-
ration from free water surfaces such as streams, lakes, and reservoirs.
However, while numerous theoretical and empirical equations have been pub-
lished, this kind of evaporation is usually estimated directly from pan evapo-
ration data.  For example, reservoir or lake evaporation has been observed to
be reasonably well approximated as about 70 percent of pan evaporation for the
same site.  While free water surface evaporation is only a small part of the
total evapotranspiration from a vegetated area, it is interesting to note that
potential evapotranspiration is also fairly well approximated as 70 percent of
pan evaporation.   Thus, at least during the wetter portions of the year, it
may be possible to estimate evapotranspiration from a hazardous-waste disposal-
site cover system using this rule of thumb.  However, it must be remembered
that as the soil  moisture content drops appreciably below field capacity, the
rate at which evapotranspiration can occur will be severely limited by the
availability of water to plants.

    A number of theoretical and empirical equations for estimating evapotran-
spiration from vegetated soil systems have appeared in the literature.   Several
of the more commonly used ones are presented and discussed by Chow (1964).
One of the most useful expressions is the Penman equation as modified by
Ritchie (1972) and presented below.


                                     1.28(A)(H)                         (  1 }
                                   25.4(A + 0.68)                       ^'   ;
                                      4-33

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where
         PET = the potential daily evapotranspiration (inches),
           A = the slope of the saturation vapor pressure curve,
           H = the net daily solar radiation (langleys).

(A langley is a unit of solar radiation equivalent to one gram calorie per
square centimeter of irradiated surface.)  The slope of the saturation vapor
pressure curve, A ,  may be estimated from the following expression.


                        A = 5304 (e) (21.255 - 5304/T)                  (4

                            (T)2

where
         T = the mean daily temperature (°K).

(Temperature conversion:  °K = °C + 273; e.g., 293°K = 20°C.)  The net daily
solar radiation, H , may be estimated from the following equation.


                                  _ (1 - L)(R)                          ,.
                                H~ 	5O	                          (4


where
         L = the albedo for solar radiation,
         R = the incident daily solar radiation (langleys).

Values of average albedo (portion of incident radiation that is  reflected) for
various types of land surface may be found in textbooks in climatology and
hydrology (e.g., Critchfield, 1974).

    Thornthwaite and Mather (1957) introduced an empirical method for esti-
mating evapotranspiration from bare soil and vegetated areas, which has been
widely used.  The principal disadvantage to the method is that extensive
tables found in the original reference (Thornthwaite and Mather, 1957) are
required to make the estimates.  This technique is part of the manual water-
balance method discussed below.  Example applications are given in Fenn,
Hanley, and DeGeare (1975).

    In summary, evapotranspiration accounts for the major portion of the soil
moisture lost from a typical well-vegetated cover system.  Thus, care should
be used in arriving at  the numerical values used in estimating percolation.
Water-balance methods that take into account the fact that evapotranspiration
rate is a function of soil moisture content are much to be preferred.  Both
the methods discussed below include this feature.  The computerized method
calculates potential evapotranspiration by equation (4.16), but limits actual
evapotranspiration, depending upon the availability of soil moisture to the
vegetation.  The manual method makes use of the Thornthwaite method (Thornth-
waite and Mather, 1957), which also takes soil moisture content into account.
                                      4-34

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    4.2.7 Methods of Water-Balance Analysis


    As previously discussed, virtually all methods of estimating leachate
production or percolation require some form of water-balance procedure.  The
principal factors that affect the difficulty involved are the quantity and
quality of the data available and the accuracy desired.  Two published proce-
dures are considered below.  The first is a manual technique that is suitable
for constructing a monthly water balance.  While greater accuracy could be
obtained by using a daily time period, the monthly procedure is very useful in
that it requires a minimum of data and effort, and has been shown to produce
reasonable results.  The second procedure considered is an easy-to-use computer
model that operates on a daily time period.  Lutton, Regan, and Jones (1979)
discuss other water-balance procedures applicable to cover systems.


         4.2.7.1 A Manual Water-Balance Method
    Fenn, Hanley, and DeGeare (1975) have published a simplified manual proce-
dure that can be conveniently used to construct a monthly water balance for a
hazardous-waste disposal-site cover system.   While the method can also be used
with a daily time period, such a use would appear impractical given the compu-
tational effort involved.

    (1)  Estimating percolation.   Percolation is calculated by a simple mass-
balance procedure after other components of the water budget have been deter-
mined.   The fundamental mathematical relationship may be expressed as shown
below.

                           PERC = P - RO - CST - AET                    (4.19)

where
         PERC = percolation,
            P = precipitation,
           RO = surface runoff,
          CST = change in soi1-moisture storage,
          AET = actual evaporation.

All terms in equation (4.19) must be expressed in the same units.   The general
procedure to be used with equation (4.19) is summarized below.   For more de-
tailed discussion, complete with numerical examples, see Fenn,  Hanley, and
DeGeare (1975).

    Precipitation data corresponding to the selected time period must be used.
For a monthly balance, the logical choice is historical  mean monthly precipi-
tation if the goal is to estimate average percolation production.   However, if
it is desired to estimate peak rates of percolation, hypothetical  data for a
very wet year may be used.  Thus, the choice of precipitation data depends
upon the intended use of the results.

    Surface runoff is estimated directly from precipitation by means of runoff

                                      4-35

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coefficients.   Typical coefficients are presented above in the section on
runoff.   Infiltration, I ,  is estimated indirectly as the difference between
the precipitation, P , and the runoff,  RO  (i.e., I = P-RO).

    The potential evapotranspiration, PET ,  is estimated by the Thornthwaite
method (Thornthwaite and Mather, 1955,  1957).   This technique requires the use
of tables presented in the references indicated.   The potential evapotranspi-
ration may be thought of as the maximum evapotranspiration that can occur,
assuming an unlimited supply of soil moisture.

    The difference between the estimated infiltration and the potential evapo-
transpiration (i.e., [I-PET]) is used to determine whether the soil-moisture
storage should increase or decrease during a given month.   A negative value of
[I-PET] indicates that infiltration is  not sufficient to meet the evapotran-
spirative demand, and hence, soil-moisture storage may be expected to decrease,
assuming that plant-available water is  present.   A positive value of [I-PET]
indicates that more water infiltrates than can be lost to evapotranspiration.
Thus, soil-moisture storage must increase, unless the soil moisture content is
already at field capacity.

    In most locations there is an annual wet/dry cycle.   Thus, the soil-
moisture storage for the last month in  the yearly cycle having a positive value
of [I-PET] may be assumed to correspond to the field capacity.  That is, the
soil-moisture storage at the end of that month may be estimated as the product
of the depth of the soil and the dimensionless field capacity.  Normally, only
the soil depth corresponding to the root penetration zone is considered.

    The assumption that soil moisture is at field capacity at the end of the
last month having a positive value of [I-PET] (i.e., the end of the wet period)
is a reasonable one, and is very convenient since it is necessary to begin the
actual water-balance calculations with  some known value of soil-moisture
storage.  Thus, this provides a logical starting point.

    Once a starting point has been determined, the soil-moisture storage at
the end of the wet season,  it is possible to estimate the amount of percolation
to be expected for each month using equation (4.19).  However, for months when
[I-PET] is negative, actual evapotranspiration is limited by the amount of
soil moisture available for plant use.   Thus, during these months, actual
evapotranspiration, AET , is less than   PET .   Tables provided in Thornthwaite
and Mather (1955, 1957) may be used to  estimate the change in soil-moisture
storage that may be expected under these circumstances.   AET  may then be
estimated as the difference between infiltration and the change in soil-
moisture storage (i.e., [I-CST]).

    Negative values of percolation, PERC  , will be predicted by equation (4.19)
so long as the soil moisture content is less than the field capacity.  These
negative values have no direct physical significance and may, thus, be replaced
by zeros.

    (2)  Estimating leachate production.  Percolation, estimated as above,
represents water that percolates through the cover system.  Since lateral out-
flow is not considered, it follows that this water will then enter underlying

                                      4-36

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soil or water layers and ultimately become leachate.  The time lag between the
closure of a waste site and the beginning of leachate production may be esti-
mated if the initial moisture contents of all underlying soil and waste layers
are known.   That is, these layers may be expected to fill gradually with mois-
ture as percolation enters from above.  When the moisture content of a given
layer reaches field capacity, percolation will begin to pass into the next
lower layer.   Ultimately leachate is assumed to be generated at a rate equal
to the rate at which moisture percolates through the cover system.

    (3) Case studies.  Three instructive case studies were worked out and
presented by Fenn, Hanley, and DeGeare (1975), for Cincinnati, OH,  Orlando,
FL, and Los Angeles, CA, cities representing three different climates.   Inter-
estingly, there is less percolation at Orlando than at Cincinnati,  even though
Orlando has higher annual precipitation.   The reason is that high precipitation
and high evapotranspiration are nearly in phase, with respect to the yearly
cycle, in Orlando (rain concentrated in the summer months), while they are not
similarly in phase in Cincinnati (precipitation more nearly constant throughout
the year).   At Los Angeles, with a dry climate, JTO percolation is to be ex-
pected from the natural rainfall.   However interestingly also, if the final
land use of a site in Los Angeles were to be a park, where grass were watered
by irrigation, a considerable amount of percolation might be produced thereby.


         4.2.7.2 The HELP Model
    The Hydrologic Evaluation of Landfill Performance (HELP) program is an
easy-to-use, computerized water-budget model that was developed to assist
landfill designers and regulators by providing a tool to allow rapid, economi-
cal screening of alternative designs.   The program may be used to estimate the
magnitudes of various components of the water budget, including the volume of
leachate produced and the thickness of water-saturated soil (head) above
barrier layers.   The results may be used to compare the leachate-production
potential of alternative designs, select and size appropriate drainage and
collection systems, and size leachate-treatment facilities.  The program was
designed primarily for interactive use, but may be run in a batch mode.

    HELP uses climatologic, soil, and design data to produce daily estimates
of water movement across, into, through, and out of landfills.   To accomplish
this, daily precipitation is partitioned into surface storage,  runoff, infil-
tration, surface evaporation, evapotranspiration, percolation,  stored soil
moisture, and subsurface lateral drainage.   Surface runon and subsurface
lateral inflow are not considered.   Complete documentation and a user's guide
are available in Schroeder, Gibson, and Smolen (1984), and Schroeder et al.
(1984).

    (1)  Hydrologic processes.   Runoff is computed using the Soil Conservation
Service Runoff Curve Number method described above.   Factors such as surface
slope and roughness are not considered directly in estimating runoff, and
hence infiltration.  However, they may be taken into account in the selection
of a curve number.   This approach to runoff estimation is made possible by
                                      4-37

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considering only daily precipitation totals, and not the intensity, duration,
and distribution of individual rainfall events (storms).

    Percolation and vertical water routing are modeled using Darcy's Law for
saturated flow with modifications for unsaturated conditions.   Lateral drainage
is computed analytically from a linearized Boussinesq equation corrected to
agree with numerical solutions of the nonlinearized form for the range of
design specifications used in hazardous-waste landfills.   Evapotranspiration
is estimated by a modified Penman method adjusted for limiting soil moisture
conditions.   Detailed solution methods for all hydrologic processes are pre-
sented in the program documentation (Schroeder, Gibson,  and Smolen, 1984).

    (2)  Data requirements.   The HELP program requires climatologic, soil,  and
design data.   However, sufficient default climatologic and soil  data are
internally available to satisfy the needs of many users.   The basic data
requirements and input options are briefly discussed below.

    (a) Climatologic data.   Climatologic data, including daily precipitation
in inches, mean monthly temperatures in °F,  mean monthly insolation (solar
radiation) in langleys, leaf area indices, and winter cover factors, may be
entered manually or selected from built-in "default" data files.   Leaf area
indices and winter cover factors are variables used to describe the condition
of vegetative cover crops with respect to their effects  on evapotranspiration.
They are discussed further below.

    Default climatologic data consisting of five years (1974-78) of observed
daily precipitation and one set of values for mean monthly temperature, mean
monthly insolation, leaf area index, and winter cover factor for each of 102
U. S.  cities are built into the program.   These data may be accessed and used
simply by giving appropriate responses to straightforward program queries.

    The default climatologic data base includes values for two variables that
relate to the effects of vegetation on evapotranspiration; leaf area index
(LAI) and winter cover factor.  LAI is defined as the (dimensionless) ratio of
the leaf area of actively transpiring vegetation to the  nominal  surface area
of land on which the vegetation is growing.   The HELP program assumes that LAI
may vary from a minimum value of 0 to a maximum value of 3.   The former is
representative of no actively growing vegetation (i.e.,  bare ground or dormant
vegetation),  and the latter represents the most dense stand of actively growing
vegetation considered.  Default LAI data sets consist of 13 Julian dates
(spaced throughout the entire year) and corresponding maximum LAI values for a
good row crop and an excellent stand of grass.  A different set of LAI data is
provided for each of the 102 cities.  The program adjusts these maximum values
downward if necessary, depending upon the vegetative cover specified, and
interpolates for daily values in order to model evapotranspiration during the
growing season.   For the remainder of the year, transpiration is assumed not
to occur.  However, even dormant vegetation can serve to insulate the soil,
and thus affect evaporation.  Winter cover factors, which vary from 0 for row
crops to 1.8 for an excellent stand of grass, are used to account for this
effect.

    When the manual climatologic data input option is utilized, the user must

                                      4-38

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provide daily precipitation data for each year of interest.   The maximum
allowable period of record is 20 years and the minimum is 2 years.   A separate
set of temperature, insolation, LAI, and winter cover factor may be entered
for each year, or a single set of data may be used for all years.

         (b)  Vegetative cover data.  The user must specify an evaporative
(root) zone depth and, if a default option is used, one of seven types of
vegetative cover.  Acceptable default types of vegetation are bare  ground
(i.e., no vegetation), excellent, good, fair, and poor stands of grass, and
good and fair stands of row crops.   Depending upon the default vegetation type
selected, the hydraulic conductivity of the soil within the evaporative zone
is corrected for the effects of roots by multiplication by a factor varying
from 1 for bare ground to 5 for an excellent stand of grass.   The LAI values
discussed above are also modified depending upon the type of vegetation
specified.

         (c)  Design and soil data.  The user must specify data describing the
various materials contained in the landfill (e.g., topsoil,  clay,  sand, waste)
and the physical layout (design) of the landfill (e.g., size, thickness of
various layers, slopes, etc.).  Either the default or manual  input  options may
be utilized for soil data; however, design data must be entered manually.

    The HELP program may be used, to model landfills composed of up  to nine
distinct layers.  However, there are some limitations on the order  in which
the layers may be arranged, which must be observed if meaningful results are
to be obtained.  Also, each layer must be identified as either a vertical-
percolation, lateral-drainage, waste, or barrier-soil layer.   This  identifica-
tion is very important because the program models water flow through the
various types of layers in different ways.   However, in all  cases,  the program
assumes that each layer is homogeneous with respect to hydraulic conductivity,
transmissivity, wilting point, porosity, and field capacity.   A typical closed-
landfill profile is shown on Figure 4-11.  The circled numbers indicate the
layer identification system used by the program.

    Vertical-percolation layers (e.g., layer 1 on Figure 4-11) are  assumed to
have hydraulic conductivity sufficiently great that vertical  flow in the
downward direction (i.e., percolation) is not significantly restricted.
Lateral drainage is not permitted,  but water can move upward and be lost via
evapotranspiration, depending upon the specified depth of the evaporative
zone.   Percolation is modeled as being independent of the depth of  water-
saturated soil (i.e., the head) above the layer.  Layers designed to support
vegetation should generally be designated as vertical-percolation layers.

    Lateral-drainage layers are assumed to have hydraulic conductivity high
enough that little resistance to flow is offered.   Therefore, the hydraulic
conductivity of a drainage layer should be equal to or greater than that of
the overlying layer.  Vertical flow is modeled in the same manner as for a
vertical-percolation layer, however lateral outflow is allowed.   This lateral
drainage is considered to be a function of the slope of the bottom  of the
layer, the maximum horizontal distance that water must transverse to drain
from the layer, and the depth of water-saturated soil above the top of the
underlying barrier-soil layer.  The slope at the bottom of the layer may vary

                                      4-39

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                                FIGURE 4-11
 O
 oc
 Q.
 CD
 Z>
 cn

 o:
 UJ
 a.
 a.
                 TYPICAL LANDFILL PROFILE (SEE TEXT DISCUSSION

                              OF HELP MODEL)



                 I  PRECIPITATION         EVAPOTRANSPIRATION


                           r-VEGETATION       j   RUNOFF

                       i^Mfiitttfirtini'liiniiiiilfiiiiii "'i"»"'"'>

                            INFILTRATION
        VEGETATIVE  LAYER
LATERAL  DRAINAGE LAYER
                                         LATERAL DRAINAGE

                                          (FROM COVER)
                                                         SLOPE
       BARRIER  SOIL  LAYER
                                            PERCOLATION

                                       (FROM BASE OF COVER)
cc.
LU
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O
o

t_
o

0.


o
a.
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ID

-------
from 0 to 10 percent, and the maximum drainage distance may range between 25
and 200 ft.   Layers 2 and 5 on Figure 4-11 are lateral-drainage layers.

    Barrier-soil layers serve the purpose of restricting vertical flow.   Thus,
such layers  should have hydraulic conductivity substantially lower than for
vertical-percolation, lateral-drainage, or waste layers.   The program limits
the direction of flow in barrier-soil layers to downward.   Thus, any water
moving into  a barrier layer will eventually percolate through.   Percolation is
modeled as a function of the depth of water-saturated soil (head) above the
base of the  layer.   The program recognizes two types of barrier layers;  those
composed of  soil alone, and those composed of soil  overlain by an impermeable
synthetic membrane.  In the latter case, the user must specify some membrane
leakage fraction.   The net effect of specifying the presence of a membrane is
to reduce the effective hydraulic conductivity of the layer.   The program does
not model aging of the membrane.  Layers 3 and 6 shown on Figure 4-11 are
barrier layers.

    Water movement through a waste layer is modeled in the same manner as for
a vertical-percolation layer.   However, identifying a layer as a waste layer
indicates to the program which layers should be considered part of the landfill
cap or cover, and which layers should be considered as part of the liner/
drainage system.  Layer 4 shown on Figure 4-11 is a waste layer.

    If the topmost layer of a landfill profile is identified as a waste layer,
the program  assumes that the landfill is open.   In this case, the user must
specify a runoff curve number and the fraction of the potential surface runoff
that is actually collected and removed from the landfill  surface.

    Important nomenclature used by the program is indicated on Figure 4-11.
For computational  purposes, the soil profile is partitioned into subprofiles,
which are defined in relation to the location of the barrier-soil layers.   For
example, the upper subprofile shown on Figure 4-11 extends from the ground
surface to the bottom of the upper barrier-soil layer (layer 3), while the
lower subprofile extends from the top of the waste layer to the base of the
lower barrier-soil  layer.   If an intermediate barrier-soil layer had been
specified, a third (intermediate) subprofile would have been defined.   Since
the model can handle no more than three barrier-soil layers,  there can be no
more than three subprofiles.   The program models the flow of water through one
subprofile at a time with the percolation from one subprofile serving as the
inflow to the underlying subprofile, and so on through the complete profile.

         (1)  Soil  data.  The type of soil present in each layer must be
specified by the user.   He can use either the default or manual data-input
option.  Characteristics for 18 default soil types are presented in Table 4-1.
The first three columns represent, respectively, soil designations used by the
HELP program, textural  soil descriptions as used by the U. S. Department of
Agriculture, and soil group symbols according to the Unified Soil Classifica-
tion System  (USCS).  The numerical entries represent typical  data values
corresponding to the various soil types and are used by the HELP program,  as
needed, for  computational  purposes.  Default soil data may be accessed and
used simply  by entering the appropriate soil-texture number in response to a
command from the program.

                                      4-41

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    The user may also enter soil characteristics manually.   In this instance,
the program will require that numerical values be entered for porosity, field
capacity, wilting point, hydraulic conductivity (i.e., saturated hydraulic
conductivity) in inches per hour, and evaporation coefficient in millimeters
per square root of day.  (Note:   porosity, field capacity,  and wilting point
are all dimensionless.)

         (2)  Soil compaction.   Barrier-soil  layers and waste layers may be
compacted to restrict the vertical flow of water.   When using the default
soil-data option, the user has the option of specifying that any layer is to
be considered compacted.  When a layer is so identified, the hydraulic conduc-
tivity is reduced by a factor of 20, and the drainable water (i.e., porosity
minus field capacity) and plant-available water (i.e., field capacity minus
wilting point) are each reduced by 25 percent.  When using  the manual soil-data
option, the user simply enters soil data representative of  compacted soil.
Layers that support vegetation should not be compacted.

         (3)  Design data.   The user must enter the total surface area of the
landfill to be modeled in square feet, and the thickness of each layer in
inches.  For drainage layers, the slope of the bottom of the layer and the
maximum horizontal drainage distance must also be supplied.   The former may
vary from 0 to 10 percent and the latter from 25 to 200 ft.   When drain tiles
are to be used, the appropriate distance is one half the maximum spacing.
When drains are not used, the appropriate distance is the maximum horizontal
distance that water must travel  to reach a free discharge.   Depending upon the
soil profile chosen and the input option selected, other data such as runoff
curve number, membrane leakage fraction, and potential runoff fraction may be
requested by the program.

         (4)  Program output.  Basic program output, always reported, consists
of the following:  all  default and manual input information except daily pre-
cipitation data, and summary results.  Input data has been  described above.
Summary output data are described below.  Occasional reference to Figure 4-11
may be helpful in understanding some of the terminology used in describing
program output.

         (a)  Summary output.  Following the input-data summary, the program
produces a table of annual  totals for each year of operation simulated.  Spe-
cific entries appearing in the tables include total annual  precipitation,
runoff, evapotranspiration (total of surface and soil evaporation and plant
transpiration), percolation through the base of each subprofile, and lateral
drainage from each subprofile.   Each of these output variables is reported in
terms of inches, cubic feet, and as a percent of total annual precipitation.
The soil moisture content and precipitation stored in the form of snow are
reported for the beginning and the end of the year in terms of inches and
cubic feet.

    After the annual-total  tables, the program reports average monthly totals
for each of the output variables noted above except soil moisture content
and precipitation stored as snow.  All values are reported in terms of inches.
The entries shown indicate averages of the monthly totals for all years


                                      4-42

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 simulated, for example, the average total  runoff  in July  for the period simu-
 lated  (say five years).

    The next table presents average annual totals for the total period
 simulated.  Average annual values for precipitation, runoff, evapotranspira-
 tion,  percolation through the base of each subprofile, and  lateral drainage
 from each subprofile are reported in terms of  inches, cubic feet, and as a
 percent of total average annual precipitation.

    In the final table, peak day values for precipitation,  runoff, percolation
 through the base of each subprofile, lateral drainage from  each subprofile,
 and precipitation stored in the form of snow are  reported in terms of inches
 and cubic feet.  The maximum head on the base  of  each subprofile and the
 maximum and minimum soil moisture content  for  the vegetative layer are also
 reported in terms of inches.

    The data reported in these summary tables  are sufficient for rapidly
 screening alternative designs and roughly  sizing  drainage and leachate collec-
 tion and treatment systems.  However, more detailed information may be obtained
 by requesting monthly or daily output.

         (b)  Detailed output.   When the user  requests monthly output, tables
 are produced which report monthly totals (in terms of inches) for precipita-
 tion,  runoff, evapotranspiration, percolation  through the base of each subpro-
 file, and lateral drainage from each profile for each year  included in the
 simulation.

    When daily output is requested,  daily values are reported for the Julian
 date, precipitation, runoff, evaporation, head on the base of the cover,
 percolation through the base of the cover, lateral drainage from the cover,
 head on the base of the landfill, percolation  through the base of the landfill,
 lateral drainage from the base of the landfill, and the soil moisture content
 of the evaporative zone.   Where applicable the units are inches, except for
 soil moisture, which is reported in dimensionless form (i.e.,  as a fraction of
 the maximum possible value).   An additional variable is reported to indicate
 if the temperature is above or below freezing  (32°F).


         4.2.7.3 Some General  Comments  on Water-Balance Methods
    In virtually all water-balance methods, individual processes that affect
the water balance are considered separately (to the extent possible), and then
their individual contributions are summed to produce a mass balance for the
system considered.   Usually, soil moisture content is calculated by these
means, and then leachate production (percolation) is estimated from the change
in soil  moisture storage.   Thus, inaccuracy in any estimates corresponding to
the individual processes considered will result in inaccuracy in the final
estimate of leachate production or percolation.   For this reason, care must
always be exercised to ensure that each component of the water budget is given
ample consideration.  In the majority of cases,  leachate production (or perco-
lation)  will  be only a small fraction of the total water accounted for in the

                                      4-43

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balance.   Thus, a relatively small  error in estimating the contribution of one
component (e.g., a 10 percent error in estimating evapotranspiration) can
result in a relatively large (e.g., 100 percent or more) error in the estimate
of leachate production or percolation.


4.3 Gas Control


    It may be necessary to design for control  of gases when covering an uncon-
trolled hazardous waste site.  Gases are evolved wherever decayable (biode-
gradable) organic matter is buried; thus gas control  is a problem at nearly
all municipal landfills.   Where municipal and hazardous wastes were dumped at
the same site, a gas problem is likely.  Where no decayable matter was buried,
gas will  probably not be a problem.


    4.3.1 Gas Generation


    Organic refuse may generally be classified into three groups (Rovers,
Tremblay, and Mooij, 1977).  The rapidly decomposing component comprises food
stuffs and garden waste; the intermediate-decomposing component comprises
paper and wood waste; and the refractory component comprises plastic and
rubber.  The first group contains about 30 pet of the biodegradable waste,
which decays in a landfill over a period of from one to five years.  The
second group contains about 70 percent of the biodegradable waste and has a
degradation half-life of 5 to 25 years.  Thus the rate of waste gas production
decreases steadily, but some production may persist for many years.

    Within a few months of closure of a landfill, anaerobic decay conditions
stabilize, and thereafter only two gases are produced in appreciable quantity:
methane  (CH., about 55 pet by volume) and carbon dioxide (C02, about 45 pet by
volume).   Trace quantities of other gases may also be produced.

    The  most serious problem from waste gases is explosion hazard.  Methane
(and some of the trace gases) is combustible, and methane-air mixtures are
explosive over a certain range of  composition (about 5 to  15 pet methane by
volume).   An explosion hazard develops when methane migrates from a  landfill
and becomes mixed with air in a confined space.  Several tragic methane explo-
sions caused by landfill gases have occurred in  recent years (Shafer et al.
1984).

    Other actual or potential threats  from waste gases  include vegetation
distress, odor problems, property-value deterioration, physical disruption of
the cover, and toxic vapors.  Vegetation kills are a demonstrated  fact at
landfill covers.  The exact  damage mechanism may be complex, involving oxygen
starvation (asphyxiation), temperature  increase, plant  toxicity, etc.  Carbon
dioxide  as well as methane may be  responsible for vegetation damage.  The
offensive odors of  landfill  gases  are  often attributable to trace  gas compo-
nents, such  as  hydrogen  sulfide and mercaptans.  Property  values near a  land-
fill may deteriorate  largely from  the  threat of  waste  gases (Rovers, Tremblay,

                                       4-44

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and Mooij, 1977).  The threat of physical disruption of the cover should not
be discounted.  Given a highly impermeable cover and sufficient production of
gas, the gas must escape somewhere, and it will do so in an uncontrolled
fashion if no controlled exit is provided.


    4.3.2 Vapors


    Where toxic substances are buried in the absence of decaying organic
matter, the threat of their vapors* reaching the surface in dangerous quanti-
ties appears to be very small.  In an occurrence of hexachlorobenzene (HCB)
dispersal traceable to landfill dumping (Farmer et a!., 1976), elevated levels
of HCB were found in plants, cattle, and humans living near a Louisiana land-
fill.  However, the problem may have developed during a period of careless
haulage and open dumping.   Laboratory studies indicated that a soil cover
would probably reduce the rate of HCB volatilization, relative to that from
exposed material, by a factor of several thousand.   The chief problem would be
maintenance of the integrity of the cover.  The rate of migration of a vapor
should be very much lower than that of a gas such as methane or carbon dioxide,
because of the much higher equilibrium pressure of the latter at any given
temperature.   Therefore, it seems logical to expect that migration of a vapor
from beneath a soil cover would rarely lead to a hazardous situation.  The
detection and measurement of organic substances over waste sites has been a
matter of recent research in California (Karimi, 1983).   Vapor diffusion
through cover soils at landfills is discussed in Farmer et al.  (1980).


    4.3.3 Gas Treatment and Control
    Landfill gases have received considerable attention in the literature, not
only as a problem but also as a potential energy source (Rovers, Tremblay, and
Mooij, 1977; Intergovernmental Methane Task Force, 1979; Shafer et al., 1984;
Lutton, Regan, and Jones, 1979; and other sources cited in the above).   A con-
siderable body of experience with controlling landfill gas has accumulated.
The field is young, however, and any design must be highly site-specific.   The
cover designer may find it advisable to consult a contractor or consultant
with experience in the field.

    An excellent discussion of gas migration control at waste disposal  sites
may be found in Chapter 6 of JRB Associates (1982) or Rogoshewski, Bryson, and
Wagner (1983).

    A factor that needs to be considered is the possible fouling of gas drain-
age systems by the growth of a biomass of anaerobic slimes (E. Glysson, lecture
at University of Wisconsin Extension, October 1982).  This problem has  occurred
at gas drainage wells at municipal landfills.  Such slimes will grow as coat-
ings on mineral particles.  The larger the pore sizes in the gas drainage

*  Vapor is defined as a gas below its critical point (Daniels and Alberty,
  1961, p.  125).

                                      4-45

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layer, the longer it takes a buildup to block the pores completely.   Thus, the
coarser the material in the gas-drain layer, the better.

    Guidance may be found in the above-cited references.   Gas-control systems
make use of natural barriers when possible and of constructed barriers such as
trenches, membranes, wells, and vents.   The cover designer should remember,
however, that at a hazardous waste site, not all measures may be acceptable.
Engineering judgment is required, depending on the specifics of the site.

    The following guidance is taken from Rovers, Tremblay, and Mooij (1977).
Their report was the outgrowth of an international seminar held in Montreal to
consider the problem of landfill gas monitoring and control.

    Natural barriers to gas migration include moist, fine-grained soils and
saturated coarse-grained soils.  Lateral methane migration can be naturally
controlled at a landfill boundary by fine-grained soils,  such as glacial till
or natural clay deposits, and by the water table.

    Constructed control systems include trenches to the water table, permeable
trenches with or without impermeable membranes, induced exhaust or gas-
extraction systems, and vertical venting.

    At small sites situated within coarse-grained soils having a shallow
ground-water table, lateral methane migration can be controlled at a site
boundary by open trenching around the fill down to the water-table depth.

    A permeable gravel-filled trench (see Figure 4-12, 'A') may be an effective
lateral migration control system at an  existing refuse disposal site situated
in less permeable soil  having a deep water table.  The trench should be con-
structed to a depth at least equal to the depth of the landfill.   In areas
where freezing and sealing of the trench cover can occur, the permeable trench
should be outfitted with vent pipes.

    In permeable soils, a permeable trench should be provided with an imperme-
able barrier (see Figure 4-12, 'B'),  such as a plastic membrane or non-swelling
clays, to a depth at least equal to the base of the landfill.   Pipe venting
(see Figure 4-12, 'C')  should be provided between the landfill and the imper-
meable barrier in areas where freezing  and sealing of the trench or land
surface may occur.

    An induced exhaust system (see Figure 4-12, 'D'), consisting of a permeable
trench equipped with gas vents or separately installed gas wells connected by
a header to an exhaust fan, is a most effective gas-control method.   An induced
pressure gradient of less than 1 in.  of water in the header has been found to
be effective in controlling lateral gas migration.

    An induced gas extraction system consisting of gas wells constructed
within a landfill was reported not to have been proven effective (Rovers,
Tremblay, and Mooij, 1977).

    Vertical vents, or gas wells, installed around the landfill at 30 to 60 ft
centers and down to the base of the landfill or to the water table are

                                      4-46

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                      FIGURE 4-12

GAS CONTROL  BARRIERS (ROVERS, TREMBLAY,  AND MOOIJ, 1977)
                      'A'
       Permeable Trench
                  'B'
Impermeable  Barrier
                                                P£WOBATEO Plft
               Pipe Vent
                  'D
   Induced  Exhaust
    EGENO

       GAS MIGRATION

       REFUSE

       GR«/EL

       TRENCH  COVER


       IMPERMEABLE  SARRER
                            Gas  Control  Barriers
                         4-47

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effective if connected to a header and exhaust fan.  A usual design would be
to induce a negative head of up to 10 in. of water.  Gas well and header de-
sign are discussed below.

    Gas extraction and recovery will probably be more commonly attempted at
municipal rather than hazardous waste landfills.   For recovery and utilization,
gas-extraction wells are necessary.  Figure 4-13 details the design of a gas-
extraction well.  On-site testing has shown that to get the maximum volume of
gas with the maximum BTU value, the gas-extraction well should be centrally
located in the refuse with a minimum screen of 10 ft.  At a large landfill,
multiple wells would be required.   Figure 4-13 shows that in a 60-ft landfill
the borehole of up to 4 ft in diameter would be drilled to a depth of 40 ft
with a 20-ft well screen.

    Each of the wells would be connected to a common gas-collection header
equipped with an exhaust blower.

    The well is equipped with a telescopic coupling to allow the well to
shorten should the refuse settle.

    Considerable discussion was generated at the Montreal seminar (Rovers,
Tremblay, and Mooij, 1977, p.  A-12) regarding the well diameter and need for
the gravel pack.  One opinion was that almost any well size, without a gravel
pack, would suffice, while another opinion was that larger well diameters,
preferably packed in gravel, were needed to prevent screen blockage either due
to bacterial slime formation or chemical precipitation on the screen.  It was
generally agreed that a 4 to 6-in.-diam PVC well  would perform adequately.  It
was thought that a gravel pack may not be required.

    Gas from a multiple-gas-well  system would be extracted via a gas-collection
header installed either above or  below the ground surface.   Most of the gas-
collection-wen headers are installed below the ground surface.  In some cases
they are installed in trenches dug in the surface of the ground, in other
cases soil is piled up around these headers.   The reason for covering these
headers is to protect them from external contact damage and to protect them
against extreme changes in temperature.

    Gas withdrawn from a landfill  is saturated with moisture which condenses
in the collection header.  In climates where freezing can occur, this moisture
must be removed from the header to prevent freezing.   Figure 4-14 details two
methods of moisture drainage.   In the first method, the moisture is drained to
a designed drainage connection.  This method is most useful for installation
in header pipe travelling long distances between wells or to the exhaust
system from the last well.  The recommended installation is every 100 ft.  In
the second method, collection header is sloped to drain the condensed moisture
to the gas wells although it was  suggested that this may interfere with the
program of gas extraction.

    For a more detailed discussion of gas control, the reader is referred to
JRB Associates, Inc. (1982) or Rogoshewski, Bryson, and Wagner (1983).
                                      4-48

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                 FIGURE  4-13

 GAS EXTRACTION WELL DESIGN (ROVERS,  TREMBLAY,
              AND MOOIJ,  1977)

CLAY PLUG

FINE  SAND

COARSE GRAVEL
Gas   Extraction
   Well   Design
                    4-49

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                    FIGURE 4-14
    MOISTURE CONTROL IN COLLECTION HEADER (ROVERS,
              TREMBLAY AND MOOIJ, 1977)
                     Condensate  Drain  in Header 'A*
                     Gas  Wells
                 Condensate  Drain  to Gas Weils 'B'
 LEGEND

*- Gas Flow

*• CondWfdte In  RV.C.  Ktaadw
Moisture  Control  in
 Collection  Header
                          4-50

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4.4 Filter Layer(s)


    4.4.1 General
    A filter is a layer of material placed between two materials of contrasting
gradation in order to perform one or both of the following functions:

    •    Prevent the migration of fine soil particles into a coarser-grained
         material (e.g., a riprap blanket or gravel drain).

    •    Allow water freely to enter a drainage medium (pipe or drainage
         blanket) without clogging it with fine particles of soil.

    Therefore, to insure a filter's successful operation, its design must be
addressed from both a stability and a permeability standpoint.

    Filter layer(s) may or may not be needed in a given cover design.  Places
where such a layer might be required include:

    •    Beneath the vegetative layer and above a drainage layer.

    •    Beneath a clay barrier* layer and above a coarse-grained gas-control
         layer.

    •    Beneath a riprap channel lining and above the fine-grained soil below
         the channel.

In each case the design engineer must decide on the need for a filter layer,
taking into consideration the following factors:

    •    Contrast in gradation between adjacent materials.

    •    Likelihood of migration of fines.

    •    Consequences of such migration.

If a filter is needed, its design should follow the principles given below.

    Generally two types of materials are used as filters.   One type is care-
fully graded cohesionless soil (sands and gravels).   This graded filter is
attractive by virtue of its durability,  long history of use as a filter medium,
and relatively good availability.   However, the gradation of this type of
filter requires careful design,  and the success depends heavily upon the
precision and quality of the processing and installation procedures.

    The other type of filter material is a geotechnical  fabric or geotextile.
Its advantages are:
                                      4-51

-------
   •    Manufactured in a controlled environment (factory).

   •    Requires less design work than e granular filter.

   •    Relatively simple to install.

   •    Can be installed rapidly.

   •    Can be obtained in a variety of pore sizes.

However, information on geotextiles'  performance in the waste-disposal field
is still limited.  Geotextiles do not have the history of use necessary to
predict confidently what their characteristics will be after extended exposure
to the conditions which could be present at a hazardous-waste site.   Also, a
geotextile, being a relatively thin material, is susceptible to damage during
installation and the construction of subsequent cover elements over it.


    4.4.2 Granular Filters
    Criteria for the design of filters of either type of material  are essen-
tially empirical in nature.   Testing programs have substantiated and refined
these empirical criteria to a point where they may be used with confidence.
Among the sources where filter criteria and discussions thereof may be found
are Cedergren (1977), Department of the Army (1978),  Anderson, Paintal, and
Davenport (1970), and Department of the Navy (1971, 1982).

    Design criteria for granular filters are given in terms of characteristic
particle sizes, e.g.  d15 ,  d8s ,  etc.   The  dls  size is the particle diame
ter such that 15 weight percent of  the soil is made up of grains finer than
d15 , etc.  Characteristic particle sizes are discussed in section 3.2.5.1.

    As mentioned, filter criteria apply to two areas, stability and permeabil
ity.   In the stability area, the designer wishes to avoid movement of soil
particles from the protected soil through the filter.  The following design
criteria have been established for  granular filters to meet that requirement:


           d15 of the filter material    _ d15F  . K
    a.  -j - - -j    <• o
         85 of the protected soil (base)    85B


    b.
         50B


    c.
         !5B
    In order to avoid excessive head loss, the permeability of the filter must
be sufficient for the drainage system it protects and:
                                      4-52

-------
                                    j
                                    d!5B
 Figure 4-15  illustrates a  typical  example  using these  relationships.
    These basic criteria can be adjusted to accommodate a base material's
                                         c

                                        d.
coefficient of uniformity (C ), which is defined as:
                                   C  = —
                                    u~ d!0
When the base material has a  C    less than  1.5, the ratio  -^=L  may be
                                                            d85B
increased to 6.  Also, if the  C   of the base material is greater than 4,
                                du
       15F
then  -j -  may be increased to 40.  Figure  4-16 presents the gradation char-
      °15B
acteristics of a group of typical  filter materials.  It is desirable that the
gradation curves of the filter and base be roughly "parallel".

    Often, a filter that will prevent the migration of the base material's
fine soil particles will itself be fine enough to migrate into the underlying
coarse material.  Therefore, a second filter, or even a series of filters, may
be needed to prevent the contamination of the coarse layer or the loss of soil
from the base layer (Figure 4-17).  The second filter should treat the first
filter layer as a base material in its design.  Other parameters involved in a
filter layer's design are presented in Table 4-9.

    To avoid movement of granular  filter material through perforations in
drainage pipes, the following criteria should be followed.


         85 of the filter material ^ , 0 , , . .   .  .   ,
    a"   - slot width - > 1"2 (s1otted P^65)


    .     85 of the filter material .,«/••     -^.u  •   T    i_ T  ^
    b.   - hole diameter - > 1'° (plpes Wlth circular holes)
    4.4.3 Geotextiles
    If a geotextile is chosen for use as a filter layer, the following
particle-size relationships must be observed:

         a.   For a geotextile adjacent to a granular material containing
50 percent or less (by weight) of fine (less than 0.074 mm) particles:
                                      4-53

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•^
in
                                                                        FIGURE  4-15

                               GRANULAR  FILTER  EXAMPLE  (FROM DEPARTMENTS  OF  THE  ARMY AND AIR  FORCE,  1979)
                loo.—r
                90
                80
                            U. S STANDARD SIEVE OPENING IN INCHES             U. S. STANDARD SIEVE NUMBERS
                            6   432  lj  1  j  i  |  34  «  11014162030405070  1OM40 200
                                                                                                              HYDROMETER
                 500
                                                                        1     05
                                                                   GRAIN SIZE IN MILLIMETERS
                                                                                                                001   0005
                                                                                                                                     00
                                                                                                                                   0001
COBBLES
GRAVEL
COARSC
FINE
SAND
COWISC
MEDIUM
FINE
SILT OR CLAY

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-------
                                   TABLE 4-9

                     GRANULAR FILTER DESIGN CONSIDERATIONS
a.  To avoid internal movement of fines, the filter material should have no
    more than 5 percent passing the No.  200 sieve.

b.  To avoid segregation, a filter should not contain aggregate sizes larger
    than 3 inches.

c.  For dispersive clays, filter tests should be conducted to evaluate the
    effectiveness of the proposed filter material.

d.  A material with a high coefficient of uniformity (C ) will tend to segre-
    gate during placement.  Therefore a  C   greater thcln 20 is usually not
    desirable.

e.  Filter materials should not be skip graded.
                           85 base material (mm)       ,
                      E.O.S.* of the geotextile (mm)

                 (Total open area of the filter < 36 percent)


         b.  For a geotextile adjacent to all other soils:

                      E.O.S. < U.S.  Standard Sieve No.  70
                 (Total open area of the filter < 10 percent)

         c.  No geotextile should be used with an open area less than 4 percent
or an E.O.S. less than U.S.  Standard Sieve No. 100.

    Table 4-10 presents the designer with a list of conditions to consider
when designing a geotextile filter layer.


4.5 Foundation Layer


    4.5.1 Function of Foundation Layer


    A cover system is only as stable as the foundation it is placed upon.
Even the best cover system, placed over a site, cannot withstand the effects


*  E.O.S. = equivalent opening size.

                                      4-56

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                                  TABLE 4-10

                       GEOTEXTILE FILTER CONSIDERATIONS
a.  If gravel is to be placed on a geotextile, the supporting slopes should
    be 2H:1V or flatter to prevent the gravel from sliding.

b.  If large rocks (12 inches or larger) are placed or dumped on a geotextile,
    sand should be placed above and below the geotextile as needed to protect
    from tearing.

c.  Nonwoven filter cloths, or woven filter cloths with less than 4% open area
    should not be used where silt is present in sandy soils.  A cloth with an
    equivalent opening size (EOS) equal to the No. 30 sieve and an open area
    of 36% will retain sands containing silt.

d.  When stones are to be dropped directly on the cloth, or where uplift pres-
    sure from artesian water may be encountered, the minimum tensile strengths
    (ASTM D1682, Tests for Breaking Load and Elongation of Textile Fabrics) in
    the strongest and weakest directions should be not less than 350 and
    200 Ibs, respectively.   Elongation at failure should not exceed 35%.   The
    minimum burst strength should be 520 psi (ASTM D751, Testing Coated
    Fabrics).  Where the cloths are used in applications not requiring high
    strength or abrasion resistance, the strength requirements may be relaxed.

e.  Cloths made of polypropylene, polyvinyl chloride and polyethylene fibers
    are affected by sunlight, and should be protected from the sun.   Materials
    should be durable against ground pollutants, insect attack, attack by
    microorganisms, and penetration by burrowing animals.

f.  Where filter cloths are used to wrap collection pipes or in similar appli-
    cations, backfill should consist of clean sands or gravels graded such
    that the Dg5 is greater than the EOS of the cloth.   When trenches are
    lined with filter cloth, the collection pipe should be separated from the
    cloth by at least 6 inches of granular material.

g.  The absorption of the cloth should not exceed 1% to reduce possibility of
    fibers swelling and changing EOS and percent of open area.
of massive subsidence within the materials forming its foundation.   Although
total stabilization of the subsoil and the waste containers buried within it
are beyond the scope of this Handbook, the cover designer should be aware of
the possibility and consequences of their occurrence.

    One of the most common waste containers used over the years has been the
55-gallon steel drum.  The contents of drums disposed of at uncontrolled
hazardous-waste sites rarely (if ever) received sufficient compaction to
ensure that they would not compress appreciably once the container (the drum)

                                      4-57

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deteriorated.   Also, drums were seldom emplaced in a fashion that would mini-
mize the void spaces between them.   A normal method of waste emplacement at
uncontrolled hazardous waste sites was random dumping.   Waste containers were
placed in a random fashion, with little effort placed on filling or compacting
the voids between the containers.   These conditions tend to allow temporary
soil bridges to form between containers (Figure 4-18),  especially if a cohesive
backfill material is used.  Subsequently, the voids between the containers
provide pathways for water and soil particles to migrate, and the collapse of
the soil bridges can cause subsidence of the cover.

                                  FIGURE 4-18

                                RANDOM DUMPING
                         VOIDS WITHIN ARRAY OF WASTE CONTAINERS
    Complete  stabilization of  foundation  conditions,  i.e.,  of  the  wastes and
the soils buried with them,  falls  outside the  scope of  the  cover designer,  and
in fact techniques  for that  purpose are still  in  a developmental stage.   The
designer's  task is  to take those realistic steps  that will  best solve the
problem given the current "state of the art."   In brief,  he can best attack
the problem:
                                       4-58

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    •    By selection of appropriate soils or other materials.

    •    By placement and compaction.

    •    By soil stabilization.

    The foundation layer was termed the "buffer" layer by Lutton, Regan, and
Jones (1979).   The cover designer's goal for a foundation layer is to obtain a
stable platform on which to build the rest of his system.  The cover designer's
challenge resembles that of a highway engineer obliged to build a road across
an area of weak, unpredictable,  or settlement-prone soils.   For this reason,
the many excellent discussions in Oglesby (1975) may be useful.


    4.5.2 Materials
    For most highway purposes, coarse-grained and granular soils are far more
satisfactory than fine-grained or plastic soils.   The same is true for the
foundation layer.  See in this connection Table 3-7 in Chapter 3, "Character-
istics Pertinent to Roads and Airfields."  Those soils rating highly for sub-
grade or subbase will perform well as foundation-layer soils.  This categori-
zation extends to nonsoil residual materials as well; thus crushed slag, mine
waste rock, or granular residuals in general should make good foundation-layer
materials.

    Local conditions, including economic conditions, determine material avail-
abilities.   Given this fact, the designer should strive as best he can to call
for materials that rate well on Table 3-7 in preference to those that rate
poorly.   He should remember that the stability of the foundation layer will
greatly influence the stability of the entire rest of the cover system through-
out its design life.

    Another reason for preferring coarse-grained materials is that often the
foundation layer will act as the gas-transmission layer.   The larger the grain
size, the more gas-permeable this layer will be,  and the more effectively will
this function be carried out.
    4.5.3 Compaction


    Densification via compaction should be one of the first methods of "soil
improvement" considered by a cover designer/contractor faced with an onsite
material which, in its present state, is unsuitable foundation material.   Com-
paction should also be the first consideration when dealing with an imported
soil whose "as delivered" condition requires improvement in order for it
to fulfill the foundation layer's requirements.   Since the concepts, design
criteria, and general quality assurance surrounding the compaction process
are covered in Chapters 3 and 6, this section is concerned with the mechan-
ics of field compaction, with some information dealing with some special
                                      4-59

-------
considerations which should be given to the correlation of the laboratory and
field verification testing to the field compaction process.

    In the design and construction of the foundation layer,  the construction
of test sections can be of considerable value to both the cover designer and
the construction contractor.   A test section is a small section of the cover
that is constructed using the specifications generated from laboratory testing
or those currently in force.   This section can be incorporated into the site's
actual cover or it can be constructed elsewhere (such as the borrow area).
Test sections aid the designer and contractor by defining the variables asso-
ciated with field compaction which cannot be adequately or realistically
observed in the laboratory.  Among the reasons for which a cover designer
should consider specifying the construction of a test section are:

    •    To verify that the compaction procedure yields the desired moisture-
         density relationship prior to the initiation of an extensive con-
         struction effort.

    •    To determine if the desired moisture-density relationship can be
         economically obtained in the field.

    •    To determine if the effects of compaction-related degradation and
         segregation of the coarse-grained fill would have an adverse effect
         upon a secondary function of the foundation layer.   An example of
         this would be if a coarse-grained foundation layer would also be
         expected to serve as a gas collector.

    •    If the contractor wants to use equipment or a compaction procedure
         other than that permitted by the specifications.

    •    If the contractor does not have experience with the material being
         used in the foundation layer.

Generally, the types of information from a test section include:

    •   The most effective type and use of equipment for adding and (uni-
         formly) mixing the appropriate amount of water into the soil and
         compacting it to  the desired density.

    •   The optimum loose lift thickness of  the layer to be compacted.

     •   The required number of passes a compactor must make.

     •   The ranges of water contents that  can be obtained  in  the  field  to
         obtain the desired density for a given compaction  process.

     •   The amount of degradation  and segregation that occurs  during
         compaction.

     •   The physical properties  of the compacted material  in  the  field  (such
         as  density and  grain  size  distribution).


                                      4-60

-------
    Also,  the  contractor's  personnel  and  the  designer's  inspectors  receive
 "hands  on"  experience with  the  soil.

    The design engineers  should manage  the  test  section  program, although the
 construction personnel may  administer the contract  under which the  section  is
 constructed.   Also,  construction  control  of the  test  sections should be very
 strict,  or  the data  may be  of questionable  value.   Methods applicable  to the
 construction and testing  of a test  section  are contained in  EM 1110-2-1911,
 "Construction  Control for Earth and Rock-Fill Dams" (Department of  the Army,
 1977).

    The two variables which greatly affect  the ease with which a desired den-
 sity  can be obtained are  the field  compaction effort  and the placement water
 content.  The  field  compaction effort is  affected by  the contact pressure of
 the compactor  on the soil,  the number of  passes  the compactor makes on the
 soil, and the  lift thickness.  Equipment  variables which can affect the amount
 of compactive  effort it can apply are:

    •   For a  sheepsfoot roller:

         Drum  length and  diameter
         Weight (ballasted)
         Arrangement of feet
         Length and  face area of feet

    •   For a  rubber-tired roller:

         Tire  inflation pressure
         Spacing of  tires
         Wheel   loads (ballasted)

    •   For a vibratory roller:

         Static weight
         Imparted dynamic force
         Operating frequency of vibration
         Drum diameter and  length

    The compaction effort can also be increased by decreasing the  lift thick-
ness.   Generally,  as a rule of thumb,  lifts  of impervious and semipervious
soils are placed in 6- to 8-in.  loose thicknesses for  a sheepsfoot roller.
According to Department of the Army  (1977),  this  thickness  can be  increased  to
9 to  12 in.  if  the soil  is to be compacted with a 50-ton rubber-tired roller.
However, the USBR recommends (U.  S.  Bureau of Reclamation,  1974a)  using 8-  to
9-in.  loose lifts with 12 passes of  a 20-ton dual-drum roller.   The USBR chose
this guidance because they feel  that the laboratory standard which they use
for control (ASTM D-698)  has the same intensity of effort.   Table  3-7 provides
general  guidance as to the compaction equipment requirements for different
types of soils.  Usually the standard density desired  in a  compacted soil
ranges from 90  to 95 percent Standard Proctor.
                                      4-61

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    As discussed in Chapter 3,  when the water content for a certain soil  under
a given compactive effort deviates from optimum,  the densities obtained will
be less than the maximum obtainable.   For a soil  at a water content less  than
optimum, an increase in the compactive effort will  generally increase the
soil's density.   However, a soil  with a water content considerably greater
than optimum will tend to shear under increased compactive effort rather than
compact.

    The thickness of the foundation layer will usually be controlled by:

    •    The distance the designer or contractor wishes to maintain between
         his personnel and machinery and the site's surface (especially if the
         surface is contaminated).

    •    The irregularities (gullies and hills) which must be overcome to
         obtain a good working surface.

    •    The bearing capacity of the foundation layer material itself.

    •    The amount of compaction pressure the designer wishes to impose upon
         the site's original surface.

    The first two factors are site-specific and will have to be addressed
according to the site's degree of surface contamination and topography as well
as the requirements imposed on the contractor in relation to worker safety and
equipment decontamination.  A bearing-capacity failure occurs when the shear
strength of the soil is exceeded.  Since the computation of bearing capacity
can be a complex operation and highly dependent upon material characteristics,
only a qualified geotechnical engineer should attempt it.  Information con-
cerning shear-strength determination, ultimate and allowable bearing capacity,
and how these correlate to fine- and coarse-grained materials can be obtained
in Peck, Hanson, and Thornburn (1974), Department of the Navy (1971), and
Departments of the Army and Air Force (1982).  The last factor may arise when
the designer may not wish the compaction machinery to disturb or shear the
site's original surface while it compacts the foundation layer's first lift.
The problem can usually be remedied by increasing the lift thickness or de-
creasing the weight of the machinery.  However, the designer should be mindful
that this remedy will cause an increase in the number of passes required.
Table 4-11 lists typical properties of compacted soil materials.


    4.5.4 Soil Stabilization


    As mentioned in Section 3.3,  the primary  soil-stabilizing additives are
cement, lime, fly ash, and bituminous materials.  Choosing between these
additives will have to be done on a  case-by-case basis as their suitability,
availability, and cost vary with  the different soil types and geographical
regions.  However, there  are tests which are  used on all additive-stabilized
mixtures which yield  many of the  design characteristics  of the mixture.  These
tests and parameters  are  found in Table 4-12.


                                       4-62

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                                                          TABLE  4-11
                                 TYPICAL  PROPERTIES  OF  COMPACTED MATERIALS




Group
symbo 1
GW


GP


GH


GC


SW


SP


SM


SM-SC


SC


ML

ML-CL


CL


OL


MH


CH

OH





Soil type
Well graded clean
gravels, gravel-
sand mixtures
Poorly graded
clean gravels,
gravel-sand mix
Silty gravels,
poorly graded
gravel-sand-si It
Clayey gravels,
poorly graded
gravel-sand-clay
Well graded clean
sands, gravelly
sands
Poorly graded
clean sands.
sand-gravel mix
Silty sands,
poorly graded
sand-silt mix
Sand-silt clay
mix with si ightly
plastic fines
Clayey sands,
poorly graded
sand-clay mix
Inorganic silts
and clayey silts
Mixture of inor-
ganic silt and
clay
Inorganic clays
of low to med
plasticity
Organic silts and
si It- clays, low
plasticity
Inorganic clayey
silts, elastic
silts
Inorganic clays
of high plasticity
Organic clays and
silty clays


Range of
maximum
dry unit
weight,
pcf
125-135


115-125


120-135


115-130


110-130


100-120


110-125


110-130


105-125


95-120

100-120


95-120


80-100


70-95


75-105

65-100




Range of
optimum
moi sture ,
percent
11-8


14-11


12-8


14-9


16-9


21-12


16-11


15-11


9-11


24-12

22-12


24-12


33-21


40-24


36-19

45-21

Typical value of
compress ion
At 1 4 At 3 6 Typical strength characteristics Range of
tsf tsf Cohesion 0 Effective Typical subgrade
percent of original pacted) (saturated) envelope) permeability Range of k
height psf psf degrees Tan 0 ft/mm. CBR values Ib/cu in
0.3 06 0 0 >38 >0 79 5 x lo"2 40-80 300-500


0.4 0.9 0 0 >37 >0 74 10"' 30-60 250-400


05 1.1 -- -- >34 >0 67 >10"6 20-60 100-400

'
07 16 -- -- >31 >0.60 >10"7 20-40 100-300


0.6 1 2 0 0 38 0.79 >10"3 20-40 200-300


0.8 1.4 00 37 0.74 >lo"3 10-40 200-300


08 16 1050 420 34 0 67 5 x lo"5 10-40 100-300


0.8 1.4 1050 300 33 0 66 2 x lo"6

1
1.1 2.2 1550 230 31 0.60 5x lo"7 5-20 100-300


0.9 1.7 1400 190 32 0.62 lo"5 15 or less 100-200

1.0 2.2 1350 460 32 0.62 5 x lo"7


1.3 2.5 1800 270 28 0.54 10~7 15 or less 50-200


5 or less 50-100


2.0 3.8 1500 420 25 0.47 5 x lo"7 10 or less 50-100


2 6 3.9 2150 230 19 0.35 lo"7 15 or less 50-150

5 or less 25-100

Notes.
1.  All properties are for condition of "standard Proctor" maximum density, except values of  k  and C8R  which are for "modified Proctor" maximu
   density
2.  Typical strength characteristics are for effective strength envelopes  and are obtained from USBR data.
3.  Compression values are for vertical loading with complete lateral confinement
4.  (>) indicates that typical property is greater than the value shown.
   (--) indicates insufficient data available for an estimate.
Source:  Department of the Navy (1971)
                                                               4-63

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                                  TABLE 4-12

                          TESTS FOR STABILIZED SOILS
Design Parameter    Test Designation
                                    Title
Additive
Requirement

Unconfined
Compressive
Strength

Wet-Dry
Characteristics
Freeze-Thaw
Characteristics

Swell
Characteristics
Moisture Density
Relationship

Plasticity Index
of Mixture
Found in TM 5-822-4/AFM 88-7, Chap.  4/NAVFAC DM21.5
(Dept. of the Army, Air Force, and Navy, 1982)
ASTM D-1633



ASTM D-559


ASTM D-560


MIL-STD-621A


ASTM D-558


ASTM D-423
ASTM D-424
Compressive Strength of Molded Soil-
Cement Cylinders


Wetting-and-Drying Tests of Compacted
Soil-Cement Mixtures

Freezing-and-Thawing Tests of
Compacted Soil-Cement Mixtures
Moisture-Density Relations of Soil-
Cement Mixtures

Liquid Limit of Soils
Plastic Limit and Plasticity Index of
Soils
    Recommended sources of information on soil  stabilization are "A Basic
Asphalt Emulsion Manual" (Asphalt Institute,  1979),  "Soil  Stabilization for
Pavements" (Departments of the Army,  Air Force,  and  Navy,  1982), and McDowell
(1972).   In addition, the reader may  wish to  consult discussions of stabilized
soils and their applications in the Earth Manual  (U.  S.  Bureau of Reclamation,
1974b) and Oglesby (1975).
         4.5.4.1 Cement Stabilization
    Table 4-13 presents guidance for estimating cement requirements for various
soils and Figure 4-19 and Tables 4-14 through 4-16 present information required
in the design process.   Steps in this process are as follows:

    •    Select an estimated cement content from Table 4-13 according to soil
         classification, or, through testing, determine the minimum cement
         content required to obtain the desired PI of the soil.
                                      4-64

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                                     TABLE 4-13
              ESTIMATED CEMENT  REQUIREMENTS  FOR  VARIOUS SOIL TYPES
Soil  Classification'
Initial Estimated Cement  Requirement
          Percent Dry Weight
GW-SW
GP, SW-SM,  SW-SC,
  SW-GM,  SW-GC
GM, SM,  GC,  SC,
  SP-SM,  SP-SC,
  GP-GM,  GP-GC,
  SM-SC,  GM-GC
SP, CL,  ML,  ML-CL
MH, OH
CH
                  5
                  6
                 10
                 11
                 10
 Soil classification  corresponds  to  MIL-STD-619B.
Source:   "Soil Stabilization for  Pavements" (Departments of  the Army, Air
          Force, and Navy,  1982)
                                     TABLE 4-14
                  AVERAGE CEMENT REQUIREMENTS FOR GRANULAR AND SANDY SOILS
Material
Retained on
No. 4 Sieve
percent

0-14


15-29


30-45

Material
Smaller
Than
0.05 mm
percent
0-19
20-39
40-50
0-19
20-39
40-50
0-19
20-39
40-50
Cement Content,
, Percent by
Weight

Maximum Dry Density, Ib/cu ft (Treated Material)
116-120
10
9
11
10
9
12
10
11
12
121-126
9
8
10
9
8
10
8
9
11
127-131
8
7
9
8
7
9
7
8
10
132-137
7
7
8
6
6
8
6
7
9
138-142
6
5
6
5
6
7
5
6
8
143 or more
5
5
5
5
5
6
5
5
6
 Note:  Base course goes to  70 percent retained on the No. 4 sieve.
 Source:  "Soil Stabilization for Pavements" (Departments of the Army,  Air Force, and Navy, 1982)
                                         4-65

-------
 OR LESS
          15
                                FIGURE 4-19

               GROUP  INDEX FOR SOIL-CEMENT MIXTURES
     PERCENT PASSING NO.  200

20    25     30     35     40    45
                                                                OR MORE
        75           65           55           45

OR MORE             PERCENT PASSING NO. 200

NOTE.  GROUP INDEX  - INDEX a + INDEX b.
                                                             35
                                               OR  LESS
                     (Reprinted from Soil-Cement Laboratory Handbook (EB052.06SI
                     with permission of the Portland Cement Association. Skokie, Illinois.)
                                     4-66

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                                          TABLE 4-15
                           AVERAGE CEMENT REQUIREMENTS FOR SILTY AND CLAYEY SOILS
Group
Index3

0-3



3-7



7-11



11-15



15-20


Material
Between
0.05
and
0.005 mm
percent
0-19
20-39
40-59
60 or more
0-19
20-39
40-59
60 or more
0-19
20-39
40-59
60 or more
0-19
20-39
40-59
60 or more
0-19
20-39
40-59
60 or more

99-104
12
12
13
—
13
13
14
15
14
15
16
17
15
16
17
18
17
18
19
20
Cement Content, Percent by Weight
Maximum Dry Density, Ib/cu ft (Treated Material)
105-109
11
11
12
--
12
12
13
14
13
14
14
15
14
15
16
16
16
17
18
19
110-115
10
10
11
~
11
11
12
12
11
11
12
13
13
13
14
14
14
15
15
16
116-120
8
9
9

9
10
10
11
10
10
11
11
12
12
12
13
13
14
14
15
121-126
8
8
9

8
9
10
10
9
9
10
10
11
11
12
12
12
13
14
14
127-131
7
8
8

7
8
9
9
8
9
10
10
9
10
11
11
11
11
12
13

132 or more
7
7
8

7
8
8
9
8
9
9
10
9
10
10
11
10
11
12
12
      aTaken from Figure 4-19.
      Source:  "Soil Stabilization for Pavements" (Departments of the Army, Air Force, and Navy, 1982)

                                      TABLE 4-16

                                DURABILITY REQUIREMENTS
  Type of Soil
    Stabilized8
 Maximum Allowable Weight Loss  After  12
       Wet-Dry  or Freeze-Thaw Cycles
     Percent of Initial  Specimen Weight
Army and Air Force                      Navy
Granular, PI  <  10
Granular, PI  <  10
Silt
Clays
         11
          8
          8
          6
14
14
14
14
 Refer  to MIL-STD-619B  and MIL-STD-621A
                                          4-67

-------
    •    Determine moisture-density relationship of soil-cement mixture.

    •    Vary the cement content until the values obtained in the test are
         within ± 2 percent of that shown in Tables 4-14 or 4-15.

    •    Perform unconfined compression test to ascertain that mixture will
         support cover/construction loads.   The Army and Air Force recommend a
         minimum (unconfined) compressive strength of 250 psi, while the Navy
         recommends 300 psi for cement, and 150 psi for lime, stabilization of
         a subgrade/subbase material  beneath a flexible pavement.

    •    Perform wet-dry and freeze-thaw testing and compare with values in
         Table 4-16.
         4.5.4.2 Lime or Lime-Based Stabilization
    Lime, lime-cement, and lime/cement/fly-ash require the same type of trial -
and-error procedure,  which varies in the testing requirements for the lime
content (which is pH  based) and the additional testing required for fly-ash
quality (ASTM C593).   The preferred method of determining the initial design
lime content is to prepare several  mixtures and determine the pH of each.   The
lowest lime content producing the highest pH is the initial  design lime content
with which to begin the moisture-density, strength and durability testing.


         4.5.4.3 Bituminous Stabilization


    Generally, bituminous materials work best in coarse-grained soils,  as
their effectiveness is directly related to the degree of penetration or homo-
geneity they attain in the soil mass.   Table 4-17 provides recommended  ranges


                                  TABLE 4-17

                    RECOMMENDED GRADATIONS FOR BITUMINOUS-
                         STABILIZED SUBGRADE MATERIALS

Sieve Size
3
No.
No.
No.
in.
4
30
200
Percent Passing
100
50-100
38-100
2-30

          Source:   "Soil  Stabilization for Pavements"  (Departments
                   of the Army,  Air Force, and Navy,  1982)

                                      4-68

-------
of gradation for bituminous-stabilized subgrade materials.   These ranges can
be regarded as applicable when considering bituminous stabilization of the
foundation layer.   Table 4-18 provides guidance as to which asphalt grades are
applicable to which aggregate gradation.
                                  TABLE 4-18

                          ASPHALT AGGREGATE GUIDANCE


1.   Open Graded Aggregate             RC-250, RC-800, MC 3000, MS-2, and CMS-2

2.   Well Graded Aggregate with        RC-250, RC-800, MC-250, MC-800, MS-2,
    Little or No Material Passing     CMS-2, SS-1, CSS-1
    the No.  200 Sieve

3.   Aggregate with a Considerable     MC-250, MC-800, SC-250, SC-800, SS-1,
    Percentage of Fine Aggregate      SS-lh, CSS-1, CSS-1h, MS-2, CMS-2
    and Material Passing No.  200
    Sieve

RC = Rapid Curing
MC = Medium Curing
SC = Slow Curing
MS = Medium Setting
SS = Slow Setting
CMS = Medium Setting Emulsions
CSS = Slow Setting Emulsions
4.6 Hydraulic Barrier Layer


    4.6.1 General


    The primary function of the hydraulic barrier is to divert or impede the
downward percolation of any water coming into contact with it.   The ability of
this layer to perform its function is critical to the success of the cover
system.  The hydraulic barrier constitutes the primary and final impediment to
the passage of any water percolating down from the upper layers of the cover
system.  Therefore, the designer should require a high degree of confidence in
the methods and materials used in the design and construction of this layer,
as its failure will represent a major reduction in the efficiency of the cover
system.

    The materials being considered and used in cover systems at waste sites
are largely the same materials that have been used as liners for waste im-
poundments and solid waste landfills.  Although the initial design procedures
are alike or similar, the conditions which must be designed against, as well

                                      4-69

-------
as the consequences of imperfections in the hydraulic barrier,  differ between
covers and liners.   The hydraulic barrier in a cover system should not experi-
ence the hydraulic head (depth of water over the barrier) that an impoundment
liner would.   By and large, the cover barrier will  be exposed only to water,
while the liner is exposed to whatever chemicals are at the site.   Also,  the
length of time that the overlying soil layer will  remain in a saturated condi-
tion will be much less for a cover system than a liner.   Consequently, the
amount of leakage due to pinholes, cracks, or other minute avenues through the
hydraulic barrier in a cover system will  generally  be less than through a
liner at the same site.

    The severity of the problem represented by such leakage will  depend upon
the amount the designer decides is tolerable for the site and the consequences
the leakage would have upon the stability of the cover system as  a whole.
Particular attention should be paid to the consequences of leakage through the
hydraulic barrier where the in situ soils beneath the wastes (which provide
the support for the cover system) are of  a collapsible nature.   Leakage can
also have a detrimental  effect if the soils are prone to swelling or heaving
from frost action.   However, as discussed in section 4.11, the latter will
probably not be a problem in a well-designed cover  system, and swelling is not
generally a problem if the overlying load is sufficient, thus if  the cover
system as a whole is thick enough.  Heaving will be a major consideration
where more brittle materials (asphalt concrete and  soil-cement) are used as
barrier materials.
    4.6.2 Failure Mechanisms
    There are three primary failure mechanisms which the hydraulic barrier
materials might undergo:   chemical, mechanical, and environmental.


         4.6.2.1 Chemical


    As previously mentioned in Chapter 3, "Nonsoil Materials," if the hydrau-
lic barrier material is to be placed in a zone where it will make contact with
the chemicals disposed of at the site, then chemical compatibility testing of
the material must be performed.   Table 4-19 presents guidance on a variety of
materials and their compatibility with some general types of chemical wastes.
However, as the composition and concentration of the chemicals which might be
encountered at a Superfund site could vary considerably from site to site, the
designer should, if possible, rely on laboratory testing results rather than
general product guidance.


         4.6.2.2 Mechanical

    Mechanical failure encompasses the stresses which the hydraulic barrier
material may undergo during its installation and service in the field.  Some
of the more general causes of mechanical failure are:

                                      4-70

-------
                                      TABLE 4-19

                              CHEMICAL COMPATIBILITY GUIDANCE3
Substance
Animals oils
Petroleum oils
(no aromatics)
Domestic sewage
Salt solutions
Base solutions
Mild acids
Oxidizing acids
Petroleum oils

PE
OKb
OKb

OK
OK
OK
OK
NR
Q

Hypalon
OK
0

OK
OK
OK
OK
NR
NR

PVC
ST
NR

OK
OK
OK
OK
NR
NR

Butyl
Rubber
OK
NR

OK
OK
OK
OK
NR
NR
Type of Lining
Neoprene
OK
SW

OK
OK
OK
OK
Q
NR
Asphalt
Panels
Q
NR

OK
OK
OK
OK
NR
NR

Asphalt
Concrete
Q
NR

OK
Q
OK
OK
NR
NR

Concrete
NR
OK

OK
NR
Q
NR
NR
OK

CPE
OK
OK

OK
OK
OK
OK
NR
NR

3110
OK
OK

OK
OK
OK
OK
NR
NR
  aAdapted from Kays (1977).  For details of pertinent compatibility testing, see Haxo et al. (1980,
   1983) and August et al.  (1984).

   Must be a one-piece lining
   OK = Generally Satisfactory
    Q = Questionable
   NR = Not Recommended
   ST = Stiffens
   SW = Swells

    »     Tearing or cracking of  the material due to  impact from construction
          equipment (Figure 4-20(a)).

    •     Tensile stresses generated by being placed  on  too steep a slope
          (Figure 4-20(b)).

    •     Tensile stresses resulting from subsidence  of  the underlying founda-
          tion (Figure 4-20(c)).

    •     Intrusion of particles  from an upper or lower  coarse-grained layer
          into hydraulic barrier  (Figures 4-20(d-e)).

    •     Puncturing or cracking  the material by compacting or operating over
          it  with an inadequate protective layer (Figure 4-20(f)).

    Realistically,  mechanical failure is probably a  much  greater threat than
chemical  failure.   An important  element in guarding  against it is  high-quality
inspection during  construction (see Chapter 6).   If  a polymeric membrane is
used,  it  should  be one with high elongation.  The thinner the barrier, the
greater is the threat of mechanical  failure.  A thick barrier of compacted
soil, while  not  completely impervious,  will be much  more  inherently durable
and resistant to mechanical failure than a barrier consisting of a single thin
membrane  or  member.

                                        4-71

-------
                                            FIGURE 4-20

                              TYPES  OF  MECHANICAL  FAILURES
          -HYDRAULIC BARRIER


a CONSTRUCTION MACHINERY DAMAGE
                                                             COARSE MATERIAL PUNCTURES HYDRAULIC
                                                             BARRIER FROM UNDERNEATH
                                   'QRAUUC BARRIER
                                       T = TENSILE STRESS ON
                                          HYDRAULIC BARRIER
                                       F = FRICTION FACTOR
       b TENSILE STRESS GENERATED BY OVERBURDEN
         AND DEGREE OF SLOPE (*)
                                                                  -HYDRAULIC

                                                                   BARRIER
BREAKS DUE TO STRESSES^
  FROM COMPACTOR'
                                                                      I  INSUFFICIENT PROTECTIVE LAYER
                                           c SUBSIDENCE
                                                      COMPACTIVE EFFORT
                                 UPPER LAYER OF COARSE MATERIAL PUNCHES DOWN
                                 THROUGH HYDRAULIC BARRIER
                                                   4-72

-------
         4.6.2.3 Environmental
    Environmental failure mechanisms involve damage from weathering, burrowing
animals, and plant roots.  The weathering process does not solely consist of
direct exposure to the elements (wind, rain, sunlight, snow, etc.).   Since, in
almost all cases, the hydraulic barrier will be covered as quickly as possible,
the designer should consider the effects of freeze-thaw cycles (especially if
the barrier is above the frost depth), the effects of the cycles of wetting
and drying occurring in the soil as well as how long it remains wet, and the
natural chemical nature of the soil.  All these elements combine to "weather"
the barrier.

    Burrowing animals and plant roots are a great danger to the cover system
as a whole and to the hydraulic barrier in particular.  Although the more
rigid materials like soil-cement and asphalt concrete are more resistant to
attack, they are not completely immune.   A burrowing animal can do extensive
damage.  For example, a badger can leave a maze of 6 to 8-in.-diam tunnels
through a cover system (Figure 4-21).  This provides surface water with an
avenue of infiltration, and the burrowing animals bring contaminated soil and
debris to the surface during their digging.   Plant roots can clog a drainage
system and penetrate the hydraulic barrier,  leaving avenues for infiltration
when the tree or plant dies (Figure 4-21).
                                  FIGURE 4-21

                               BIOTIC INTRUSION
                                      4-73

-------
    Methods to combat the threat of environmental failure are discussed in
section 4.8 "Biotic Barrier."
    4.6.3 Barrier Materials


    Materials suitable for use as hydraulic barriers were discussed in
Chapter 3.  These materials can be categorized as follows:

    •    Soils

    •    Soils amended with additives

    •    Nonsoil materials


         4.6.3.1 Soils
    The materials usually first considered for use in any element of a cover
system are the soils that are found onsite or that can be imported from a
local source.   As shown in Table 4-20 and as discussed in Chapter 3, permea-
bilities vary from soil type to soil type.   Tables 3-7, 3-8, and 3-9, and the
accompanying text, should make clear these types of soils that are applicable
as a hydraulic barrier.  The expected percolation performance of a soil barrier
system may be predicted using one of the water-balance methods discussed in
section 4.2.

    It is most important that a soil barrier layer be thoroughly compacted.
Compaction of at least 95 pet of Standard Proctor maximum density should be
called for in all cases.   Except with heavy clays, it is difficult to over-
compact.   Heavy clays compacted at optimum moisture content may swell if more
moisture becomes available.   They should, therefore,  be compacted wet of opti-
mum (Oglesby,  1975,  p 448).   In fact, any given soil  will be more imperme-
able compacted wet of, rather than at, optimum moisture content.   Too much
moisture, however, may lead to "pumping" of the soil.   The judgment of an
experienced field engineer is probably the best guide.


         4.6.3.2 Amended Soils


    The modification of soils using additives was discussed in Chapter 3.  One
of the most commonly used additives for the purpose of reducing permeability
is sodium bentonite.   Table 4-21 affords the designer some guidance as to
application rates, but the amount of bentonite that is required should be
determined by a program of laboratory testing.   The following variables should
be investigated as to their impact upon the coefficient of permeability of the
amended soil:
                                      4-74

-------
                                              TABLE 4-20
                10'
1.0
                           SOIL PERMEABILITY  GUIDANCE
                      Coefficient of Permeability k in cm per sec (log scale)
                         10-'     10-'     10-»      10-«    10-'     10-«
                                                                                  10-'
                                                                          10-'
Drainage
                       Good
                                        Poor
     Practically Impervious
         Clean gravel
  Soil
  types
                 Clean sands, clean sand and
                 gravel mixtures
                          Very fine sands,  organic  and inor-
                          ganic silts, mixtures of sand silt and
                          clay, glacial  till,  stratified clay  de-
                          posits, etc.
                                           "Impervious" soils modified by effects of vege-
                                           tation and weathering
        "Impervious"  soils,  e.g.,
        homogeneous  clays  be-
        low zone  of  weathering
 Direct
 deter-
mination
  of fc
Direct  testing of soil in its  original position—pumping
tests. Reliable if properly conducted.  Considerable experi-
ence required
         Constant-head  permeameter.  Little  experience
         required
Indirect
 deter-
mination
  of ft
                  Falling-head   permeameter.
                  Reliable.  Little  experience
                  required
                          Falling-head  permeameter.
                          Unreliable.  Much  experi-
                          ence required
Falling-head  permeameter.  Fairly
reliable.   Considerable  experience
necessary
Computation  from grain-size distribution. Appli-
cable  only  to  clean  cohesionlcss  sands  and
gravels
   Source:   Terzaghi and Peck  (1967)
                                                           Computation  based  on
                                                           results  of  consolidation
                                                           tests. Reliable. Consider-
                                                           able  experience  required
                                            TABLE 4-21

                SOIL  CONSERVATION  SERVICE  RECOMMENDED  SODIUM  BENTONITE
                              APPLICATION RATE FOR FARM PONDS
              Soil
                                Application Method
                                                   Application Rate
                                                           psf
     Clay

     Sandy silt

     Silty sand

     Clean sand

     Open rock or gravel
                          Pure membrane  or mixed layer

                          Mixed  layer

                          Mixed  layer

                          Mixed  layer

                          Clay or sand mixed  layer
                                                          1.0-1.5

                                                          1.0-1.5

                                                          1.5-2.0

                                                          2.0-2.5

                                                          2.5-3.0
     Source:   Lutton,  Regan,  and  Jones (1979)

                                                  4-75

-------
    •    Type of soil (which is to be amended).

    •    Type of bentonite.

    •    Quality of bentonite.

    •    Water content.

    •    Density.

         Thickness.

The required application rate,  layer thickness,  and degree of compaction (usu-
ally 95 percent Standard Proctor) can be derived from this testing program.
The most common method of constructing a soil-bentonite mixture is to spray or
dump the bentonite to a desired thickness over the soil, disk it into the soil
to the desired depth, adjust the water content (by spraying water on it or
allowing it to air dry), and compact it to the desired density.   This in-place
mixing is usually good for a layer of 6 to 8 in.  in thickness.   If a thicker
barrier is specified, then the  lower lift (layer) should be scarified and
another layer constructed over  it.

    It should be remembered that bentonite, because it contains highly active
clay minerals, is very subject  to chemical attack.

    Another type of barrier is  a bentonite membrane.   This differs from the
soil-bentonite barrier in that  it is composed solely of bentonite or the ben-
tonite is not mechanically mixed into the soil.   Two typical methods are:

    •    A suspension of bentonite in water (usually 0.05 percent of the
         water's weight) is sprayed over the area to be sealed.   Application
         rates vary with the soil type and texture.

    •    The same bentonite suspension as above  is sprayed over a gravel or
         sand bed (usually 6 in.  thick).   The bentonite settles through this
         layer and seals the voids.

    The bentonite-gravel/sand layer provides a stronger and more durable
layer, but this type of layer should not be used on a steep slope (usually
2H:1V is considered the maximum).

    Some states (Washington and Minnesota, for example) have regulations
governing the design and construction of bentonite liners for waste lagoons.
Although these regulations may  be too conservative for cover design they will
provide valuable design insight for that state and may dicate (by law) the
minimum physical standards that any hydraulic barrier used at a waste disposal
site must meet.

    Polymeric sealants have also been used to form hydraulic barriers under
waste ponds (Middlebrooks et al., 1978).   The barrier consists of alternatingly
sprayed layers of polymer and bentonite.   This type of barrier is supposedly


                                      4-76

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more resistant to chemical attack including the calcium-sodium exchange
phenomenon.

    Another hydraulic barrier employing an additive amended soil is a layer of
soil-cement.   The following lab tests should be performed to determine the
proper cement content, optimum moisture content, and maximum density of the
soil-cement mixture:

    •    ASTM D558 -  Moisture Density Test

    •    ASTM D559 -  Wet Dry Test

    •    ASTM D560 -  Freeze Thaw Test

The amount of cement  to be used in the mixture depends very much upon the type
of soil to be amended.  Table 4-22 presents some examples of some soils that
have been used by the Portland Cement Association in a program of laboratory
permeability testing.  A point that stands out is that they are all sands.
Soil-cement performs  better in coarse-grained material as it is easier to mix
the cement with this  type of material to obtain a homogeneous mix.


         4.6.3.3 Asphalt


    The various forms asphalt may assume in its applications as a hydraulic
barrier include:

    •    Surface treatments.

    •    Asphalt membrane.

    •    Asphalt concrete.

    A surface treatment may be a hot asphalt, asphalt emulsion, or asphalt
mastic material (hot  asphalt and a mineral filler) sprayed over a prepared
surface to make it more watertight.  A surface seal is normally used to fill
and seal small cracks that might form in the more rigid liners like soil
cement and asphalt concrete.  It could be considered as a hydraulic barrier by
itself but extreme caution must be utilized during construction of the subse-
quent cover layers due to the thinness of the seal (punctures easily).

    Table 4-23 presents requirements for the asphalt used in hydraulic barrier
construction.  Table  4-24 presents guidance for emulsified asphalt.

    An asphalt membrane consists of hot asphalt which is sprayed directly upon
the foundation in a sufficient thickness so that it may act as a hydraulic
barrier by itself (not as just a seal coat).  Table 4-25 presents general
guidance as to the general characteristics and testing requirements for a hot
asphalt membrane.
                                      4-77

-------
                                                                 TABLE  4-22

                                               PERMEABILITY  OF  CEMENT-TREATED  SOILS

Soil Number
or Sample
Ident Iflcation
Standard
Ottawa sand

SP sell,
1 1 11-26
Idaho


Graded Ottawa
sand

PCA soil
No. 7018
*• Florida
•vj.
00
PCA soil
No. S-2
Illinois

PCA soil
No. 6998
Maine

PCA soil
No. 6863-2
Maryland

SP sand.
1 1 II-X65
Utah
PCA soil
No. 7019
Florida


Dry
Density,
pcf
108.2
112.8
117.6
—
98.6
99.8
100.3

103.2
104.7
107.4
101.0
100.9
103.6
105.3

100.8
99.9
104.0
104.8
104.8
107.2
111.7
113.4
104.9
106.6
112.4
114.4
100.1
105.8
109.3
101. 0
106.7
108.2
108.8

Mo 1st. ire
Content,
Percent
10.8
9.4
9.7
—
24.1
20.1
18.8

13.7
13.6
12.3
12.2
13.3
12.3
12.0

14.9
14.7
15.1
15.1
10.6
9.5
10.3
10.2
10.3
10.8
10.3
10.3
16.0
14.8
13.5
13.8
13.3
13.4
13.4
Cement
Content
Percent
by Volume
0
5.7
11.3
0
8
8
20

0
5.3
10.3
0
3.1
6.3
9.2

0
3.1
6.3
9.2
0
3.3
6.8
9.9
0
3.3
6.8
10
0
6
12
0
3.1
6.5
9.5


Type of
Soil-cement
Compacted
Compa c t ed
Compacted
Plastic
Plastic
Plastic
Plastic

Compacted
Compacted
Cora pa c t ed
Compacted
Compacted
Compacted
Compacted

Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compacted
Compact ed
Compacted
Compacted
Compacted
Compacted
Compacted

K, Coefficient
of Permeability,
ft per year
48,750
6,940
76.3
2,460
130
130
0.8

16,300
473
21.4
746
562
192
21.1

4,960
1.354
59.5
1 1.5
2,400
651
36.2
7.6
1,640
90.3
25.6
3.6
356
19.8
1.1
144
33
0.3
0.02
Cement
AASHTO Reqci [ re-
USDA Gradation Analysis. Percent Passing Soil ment bv
Texture 3/4 4 10 40 200 .05 .005 Class' Volume b
Coarse (100* pass 120; OZ pass * 30) A-l-b(O)
sand

Sand 100 99 98 73 98 3 A-3(0)



#50 11 00
Sand 100 100 100 — — A-l-a(O)
28 2

Sand 100 100 100 91 7 1 — A-3(0) 10.0




Fine 100 100 100 96 13 12 2 A-2-4(0) 8.0
sand


Coarse 100 100 96 51 5 2 — A-3(0) 7.0
sand


Sand 100 100 100 77 4 — — A-3(0) 8.5



Fine 100 99 99 96 66 1 A-3(0)
sand

Fine 100 100 100 94 2 — — A-3(0) 11.0
sand


 °  All soils nonplastic.
 1  Cement requirement based on ASTM Standard Freeze Thaw and Wet-Dry Tests for Soil-Cement Mixtures and PCA Paving Criteria.

Source:  Portland Cement Association's Soil-Cement Information Bulletin   IS173.02W

-------
                                  TABLE 4-23

                     REQUIREMENTS FOR ASPHALT FOR USE IN
                       WATERPROOF MEMBRANE CONSTRUCTION
                                 (ASTM D-2521)
Softening point (ring and ball),

Penetration of original sample:

   At 25°C (77°F), 100 g, 5 s
   At 0°C (32°F), 200 g, 60 s
   At 46°C (115°F), 50 g, 5 s

Ductility at 25°C (77°F) cm

Flash point (Cleveland open cup)

Solubility in carbon tetrachloride, %

Loss on heating, %

Penetration at 25°C (77°F) after loss on
   heating, % of original
            79° to 93°C (175° to 200°F)


            50 to 60
            30 min
            120 max

            3.5 min
            218°C (425°F) min
            97.0 min
            1.0 max

            60 min
Source:   Asphalt Institute (1976)
                                  TABLE 4-24

                    SELECTION OF EMULSIFIED ASPHALT AMOUNT
         Type
    Approximate Emulsified Asphalt
Content, Percent by Weight of Aggregate0
Processed Dense Graded

Sands
Silty Sands
Semi-Processed Crusher
Pit or Bank Run

Open Graded

   Coarse
   Medium
   Fine
              5.0-10.0
              4.5-8.0
              4.5-6.5
              5.0-7.0
              6.0-8.0
aWith porous aggregates the emulsified asphalt content should be increased by
 a factor of approximately 1.2.   Porous aggregates are those which absorb more
 than 2 percent water by dry weight when tested by ASTM Method C 127.

Source:  Asphalt Institute (1979)
                                      4-79

-------
                                  TABLE 4-25

                           ASPHALT TESTING GUIDANCE

Characteristics
Softening Point (Ring and Ball), °F.
Penetration of Original Sample:
At 32°F. , 200 g. , 60 sec.
At 77°F. , TOO g. , 5 sec.
At 115°F. , 50 g. , 5 sec.
Ductility at 77°F. , cms.
Flash Point (Cleveland Open Cup), °F.
Solubility in Carbon Tetrachloride, %
Loss on Heating, %
Penetration After Loss on Heating,
% of Original
ASTM
Test Method
D36

05
D113
D92
D4a
D6
D5
AASHO
Test Method
T53

T49
T51
T48
T44a
T47
T49
Limits, ASTM
D2521
175-200

30+
50-60
120-
3.5+
425+
97.0+
1.0-
60+

General Requirements:   The asphalt shall be prepared by the refining of
                       petroleum.   It shall be uniform in character and
                       shall not foam when heated to 400°F.

aExcept that carbon tetrachloride is used instead of carbon disulphide as
 solvent, Method No.  1  in AASHO Method T44, or Procedure No.  1  in ASTM
 Method D4.

Source:  The Asphalt Institute


    Asphalt membranes formed of asphalt cement or emulsified asphalt are
usually sprayed over the ground surface at a rate of 0.25 gal/yd2 (1 liter/m2)
which will provide a membrane thickness of up to 0.04 in. (1  mm) thick.  This
spraying process is accomplished using an asphalt distributor (Figure 4-22).
Slopes should be 2H:1V maximum with 3H:1V preferable.

    Table 4-26 lists the mix compositions which are normally acceptable for
asphalt concrete used in hydraulic structures.  In general an AC-20 grade
asphalt cement or equivalent is used.  However, the type as well as the asphalt
concrete are limited by the ability of the mix to resist flowing down the
slope at placement temperatures.
                                      4-80

-------
                        FIGURE 4-22



                    ASPHALT  DISTRIBUTOR
                      •SR^-.'vVfls; "TJ^I Avi^
                           ->-5^*  >*-.*:•* ^ifS1*^]** '«
                        rt  *,' - .'**,, '-*, js ,' -J' i ***•', * f.j-p'-r -J-r

                      ^w-^c^^-^^^^fi
                      *-,',"*' ^  -     "       * ,-***-^*'- V-w.^^..
                      ..  -.5  •*' -* » - Vjf,    •- % .'    -    »    ••'*.»-
                      -—i --*- ' -t- ' " •' fc - '*",    ' -        " " ' *^
                        TABLE 4-26



         MIX COMPOSITIONS FOR FORMED-IN-PLACE ASPHALT LININGS
Sieve Size
25.0 mm (1 in.)
19.0 mm (3/4 in.)
12.5 mm (1/2 in.)
9.5 mm (3/8 in. )
4.75 mm (No. 4)
2.36 mm (No. 8)
1.18 mm (No. 16)
600 |jm (No. 30)
300 urn (No. 50)
150 jjm (No. 100)
75 urn (No. 200)
Asphalt 'cement,3
percent by wt.
of total mix
Mix type

Minimum recom-
mended com-
pacted depth
Recommended
usage
A



100
95-100
70-84
52-69
38-56
27-44
19-33
13-24
8-15
6.5-9.5


Well-graded
(low voids)
4 cm
(1-1/2 in.)

Impermeable
surface
B
Percent Passing

100
95-100
84-94
63-79
46-65
34-53
25-42
17-32
12-23
8-15
6.5-9.0


Well -graded
(low voids)
5 cm
(2 in.)

Impermeable
surface
C

100
95-100
—
72-85
53-72
40-60
30-49
22-39
16-30
11-22
8-15
6.0-8.5


Well-graded
(low voids)
6 cm
(2-1/2 in.)

Impermeable
surface
 AC-20, or equivalent AR- or penetration grade, recommended.



Source: Asphalt Institute (1976)
                            4-81

-------
    When the asphalt concrete barrier is placed in two or more courses
(layers), as is desirable to minimize joint seepage, the joints should be
offset (Figure 4-23).  The exposed edge of the asphalt concrete at the joint
should have an approximate slope of 1H:1V to ensure a good impermeable seal.
                                  FIGURE 4-23

                          JOINTS FOR ASPHALT CONCRETE
                                 ±
±
                                       JOINTS FOR COURSE 1

                                       JOINTS FOR COURSE 2
         4.6.3.4 Geomembranes
    Polymeric membranes (also known as geomembranes) have been utilized exten-
sively in the field of hazardous waste disposal.  One of their big advantages
is that they come to the site in a prefabricated form (for the most part).
The sheeting itself (excluding the field seams) has not had to endure the
rigors of the site climate in their manufacture.  However in all but the very
smallest jobs, one sheet (or panel) does not completely cover the project.
Therefore, the panels must be seamed in the field.   The field seam is the
portion of the geomembrane barrier that is its weakest link.  Failures of
field seams result from a number of causes:
                                      4-82

-------
    •    Surface contamination.

    •    Moisture or excessive humidity.

    •    Too low or too high a temperature (material).

    •    Defective adhesive.

    •    Improper adhesive system employed.

    •    Solvent evaporates before seam is made.

    •    Insufficient time allowed for tack to develop.

    •    Improper alignment of panels.

    •    Insufficient dwell time (time in which pressure is applied to the
         seam).

The geomembrane1s manufacturer should be consulted as to the proper seaming
system to be used.   Also, installers who have experience with a particular
seaming system should be preferred over others.

    Generally there are two forms in which polymeric membranes are manufac-
tured:  reinforced and unreinforced.   The reinforced membrane is considered
when tensile stresses (such as those generated on a steep slope) are present.
The unreinforced alternative is generally considered when the polymeric mate-
rial is expected to stretch to avoid failure (such as during subsidence).

    The following tests provide the designer with the information needed to
evaluate the polymeric material under consideration.


	Properties	       Test Method

Thickness, mils., ± 5%                                          ASTM D-1593
Tensile Strength, min., psi (Ibs./in.  width, min.)              ASTM D-882
Modulus @ 100% Elongation min.  psi (Ibs./in.  width, min.)       ASTM D-882
Ultimate Elongation, % min.                                      ASTM D-882

Tear Resistance:
   (a)  Elmendorf,  grams, min.  (gms./mil., min.)                ASTM D-1922
   (b)  Graves Tear, Ibs. min.  (Ibs./in.  min.)                  ASTM D-1004
Low Temperature Impact, Pass, °F                                ASTM D-1790
Volatility, % loss, max.                                         ASTM D-1203
Water Extraction (@ 104°F, 24 hrs.) % loss, max.                ASTM D-1239
Specific Gravity, min.                                           ASTM D-792
Dimensional Stability (@ 212°F, 15 min.)                        ASTM D-1204
   % max.  change
Resistance to Soil  Burial:
   Tensile Strength Loss, % max.                                 ASTM D-3083
   Peel adhesion                                                ASTM D-413
                                      4-83

-------
    The manufacturers of polymerics have various modifications to these tests
which are said to better reflect their products' quality.   However, the stand-
ard version of the test should be considered the minimum requirement and the
primary evaluation based on it.

    An alternative or backup to seaming is "shingle" construction.   This
simply involves a large overlap between the edge of one sheet and the edge of
the underlying sheet.  The overlying edge should point down hill, just as in
the shingling on a roof.  After the membrane sheeting is covered with soil,
the weight of the soil serves to hold the two sheets in contact with one
another, thus affording only an extremely narrow, long flow channel for water.
Such construction would probably not be acceptable in a liner, but might well
be satisfactory in a cover.

    The question of how steep a slope a geomembrane may be placed on is an
open one and the subject of current research.  One consideration is the ten-
sile strength of the membrane itself, and another is the possibility of ship-
ping or sliding either of the overlying soil along the membrane or of the
membrane itself along its substrate.  Martin, Koerner, and Whitty (1984) re-
ported on frictional behavior between four geomembrane materials and three
granular soils.  Measured friction angles ranged between 17 and 27 degrees,
with the commonly used HOPE consistently showing the lowest friction angles.
The interested reader should consult Martin, Koerner, and Whitty1s paper.
4.7 Drainage Layer


    4.7.1 General Principles


    The primary functions of the drainage layer in a multilayer cover system
are to intercept any water that percolates down through the layer or layers
above and to transport this water to a safe disposal outlet.  For most cases,
it will consist of a drainage blanket and a collection/transport system
(Figure 4-24).  The drainage blanket may consist of a sand and gravel layer.
The collection/transport system may consist of gravel drains.  A complex
collection/transport system might incorporate a series of collectors, laterals,
and main lines (Figure 4-25) to direct and dispose of the water entering the
drainage system.  The complexity of the system will depend on the area to be
drained, flows to be handled, and other site-specific details.

    The collector (usually a gravel drain) takes the water from the drainage
layer and transfers it to a lateral which in turn either transfers the water
to a main (to go to an outlet) or directly to an outlet.  The basic difference
between a collector and a lateral or main line is that the lateral does not
receive water directly from the drainage blanket.


    The following variables affect the design of the drainage layer:
                                      4-84

-------
VEGETATIVE  SUPPORTING
        LAYER
PERFORATED
    TOP.

-------
                            FIGURE  4-25

              COLLECTION/TRANSPORT SYSTEM PATTERNS
      collector
direction of
[~[ runoff
1)
flow in
collector
flow
i

^ — collector 	

lateral
i





                                             to main
CROSS-SECTION
                         a.  Parallel Pattern
            collectors
                                                            to outlet
                                                                to outlet
                                                                 or main
               . collectors
                       b. Herringbone  Pattern

                                4-86

-------
    •    Intensity of the design storm

    •    Evapotranspiration rate

    •    Rate of runoff at the surface

    •    Permeability of the upper layer (or layers)

    •    Permeability of the lower layers (hydraulic barrier in particular)

    The precipitation rate normally used in designing a drainage layer is that
which occurs in one hour in a ten-year storm.  The amount of water that is not
handled as runoff by the surface water management plan enters the vegetative
layer as infiltration.  Details of infiltration and runoff are discussed above
in section 4.2.

    The reader may also wish to consult the informative discussion of subsur-
face drainage for agriculture in Schwab et al.  (1981).


    4.7.2 Subsurface Drainage Design


    The following formula is presented by Moore (1980) as a method of calcu-
lating the thickness of a sand and gravel drainage blanket (see Figure 4-26):
                   i     	 L. «v *•*   **wi i  **  . -i   tan u
                   hmax

where
      h    = height to which water will rise in the blanket layer
       mat = twice the distance between drains
         c = e/k
         a = slope angle
         e = rate at which water impinges upon the drainage layer
        k  = saturated permeability of the drainage blanket

    The thickness of the drainage blanket (d) should always be kept greater
than  h    .   Determining the thickness of the drainage blanket then becomes
a  procSfs of adjusting  a , k  , and  L  to comply with the design infiltra-
tion rate.  The equation assumls that all water above the upgradient drain
will be captured by the upgradient drain.

    If a sand-and-gravel filter is used with a drainage blanket, then a
"weighted" coefficient of permeability should be used.  The following formula
(Departments of the Army and Air Force,  1979) gives a reasonable design value
for same:
                         Is. """*
                                dl + d2 + d3
                                      4-87

-------
                                  FIGURE 4-26

                           DRAINAGE BLANKET ELEMENTS
                                     L/2
where
                      k = weighted coefficient of permeability (for flow
                          parallel to layering)
         k,,  k^, k- ...  = coefficients of permeability on individual base
                          materials
         d,,  dp, d_ ...  = thicknesses of the individual layers

    Another method of determining collector spacing (Department of the Navy,
1982) involves determining the effective porosity "ne" of the drainage blanket
by the following formula:
                          n  = 1 -
         I" I
where
              dry density of the material
              specific gravity of the solids
         Y° = unit weight of water
         ww = effective water content (after the specimen has drained water
          e   to a constant weight) expressed as a decimal fraction relative
              to dry weight)

    Values for  n   usually run from 0.15 for bank-run sands to not more than
0.25 for uniformly graded medium or coarse sands.   This value is then used
with Figure 4-27 to determine the drainage blanket characteristics.  Fig-
ure 4-28 presents some examples of coefficients of permeability for clean
coarse-grained drainage material recommended for use in initial estimates.
                                      4-88

-------
                                            FIGURE 4-27

                          ANALYSIS OF  DRAINAGE LAYER PERFORMANCE
                                              RATE  OF DRAINAGE  OF  SATURATED  BASE  COURSE
                                                               IMPERVIOUS
                                                               ne=EFFECTIVE POROSITY
                                                               t = TIME
                                                               l< = COEFFICIENT OF PERMEABILITY
                0.8
                0.9
                I 0
                 001    0.02       005    01     0.2        05

                                              TIME FACTOR,  Ty *
           Select drain spacing, L, so that 50% drainage will be
            completed in 10 days.
                                      For estimate use:  t$o ~
                                                            150 drainage rate:   q = KH
                                                         2K(H +L tana)

                                                           (H t L tana)
                                                                                    2L
From Department of the Navy,  1971
                                           FIGURE  4-28

              CHARACTERISTICS OF  CLEAN  COARSE-GRAINED  DRAINAGE  MATERIAL
                     CLEAR SQUARE OPENINGS
                   no
                   US STANDARD SIEVE NUMBERS
                                           COEFFICIENT OF PERMEABILITY
                    •BS   R? 8 R 8   8   FOR CLEAN COARSE-GRAINED
                                             DRAINAGE MATERIAL
18643 2

 IttARSE I BNE
                                 O86432   186432
                                                           .1 86
                            6RAVEL
                                              SAND
                     From Department of the Navy,  1982

                                                4-89

-------
    4.7.3 Collectors
    Once the physical  and drainage characteristics of the drainage blanket
have been determined,  then a collector must be designed to handle that
capacity.  Lee et al.  (1984) provide the following guidance as to the minimum
capacity a collector (also applicable to laterals and mains) should have for
different slopes:

             Slope                     Water Removal  Rate

                                       (cfs/1000 ft of Pipe)
         Less than 2%                        1.50
           2 to 5%                           1.65
           6 - 12%                           1.80
               12%                           1.95


    General details of gravel collectors are shown in Figure 4-29.  Criteria
for filter media are found in section 4.4.

    One approach to collector design is to design the pipe to handle the flow
using the same design procedures as for open channel  flow (Manning's equation)
and then meet the specifications for a minimum gravel cover of 6 in. on the
top and sides and 2 in.  below (Department of the Navy, 1971).  The gravel used
for this purpose should have a higher coefficient of permeability than the
drainage blanket.   However, another simplified approach involves the use of
charts and nomographs.  Generally the design steps are as follows:

    •    Determine the maximum flow and/or velocity the pipe (collector,
         lateral, or main) must carry.

    •    Determine the slope (gradient) of the drain.

    •    Establish the type of pipe to be used and obtain the coefficient of
         friction.

    •    Obtain a chart or nomograph for that particular value of  n  and
         enter it with the required values of flow, gradient, or velocity and
         determine the size of pipe required.

Figures 4-30 and 4-31 present examples of such charts and nomographs.

    Table 4-27 presents some guidance as what should be specified when con-
sidering a subsurface drainage system.  Details of support for drainage tubing
are given in Table 4-28 and Figure 4-32.  Figure 4-33 shows animal guards
which should be installed in the drain outlet.


    4.7.4 Agricultural Drain Tiles


    Although agricultural drainage tiles of  concrete and clay carry water at  a

                                      4-90

-------
                                       FIGURE  4-29

                         GRAVEL  COLLECTOR CHARACTERISES
NOTE'
THE FINE FILTER SHOWN CAN BE DELETED
AND REPLACED WITH FILTER FABRIC

(IF  SUITABLE)
                                                         IH MIN. FOR SINGLE FILTER
                                          rm7777777777t*™™>
                                                          30  MIN. FOR DOUBLE FILTER
IOYEAR
 FROST
 DEPTH
                                                              PERFORATED CLOSED JOINT
                                                              DRAIN PIPE 6 MIN. DIAMETER
                                                            6" MIN.
                                               ''*v'"w/>w'/r/^-COARSE FILTER
                                          -FINE FILTER OR FILTER FABRIC DRAMAGE TRENCH


                                            Source: Department of  the Navy  (1982)
                          3"
        No.  9 Coarse
       Aggregate
          or
        No.  68 Coarse
 Aggregate  with       3"
 Plastic Filter  Cloth

 No. 68 Coarse Aggregate
-3"
              No  b8
                              Coarse Aggregate Gradations*
                                    Percent
                                                          Sieve Size
100
92 * 8
25 •>. 15
10 (Maximum)
5 (Maximum)
100
95 1 5
48 % 17
20 (Maximum)
B (Maximum)
5 (Maximum)
3/8 inch.
#4
1/8
#16
dSO
1 inch
J/4 inch
3/8 inch
us
I'S
« 16
              •Virginia Departmeni ot Highways and Transportation Specilicatioai.
               Open Graded, Percent by Weight.
                                                          Source:   Lee  et al.  (1984)
                                          4-91

-------
                                         FIGURE  4-30


                SUBSURFACE  DRAIN  CAPACITY, n  = 0.025 (LEE  ET AL.,  1984)
   0.01
   0.05
   0.02
01
01
"  0.01
  0.005
  0.002
  0.001

               Velocity =  1.4 ft./sec.
                   Flow Assumed   [
                                             IS
                                        f
           /

        **- /


        fl
                                        t
             *
                                                         7
                                                         i
                                  /

X
                                                                              :TI
0.03    0.05
                        0.1
0.2
   0.5        1.0
Capacity, ft.3/sec.
                                                                       2.0
           5.0
10JO

-------
                                                               DISCHARGE,  C FS
p
b
p
b
      p  —
      io  b
                                                                                                                                  "I1

                                                                                                                                   m
                                       CD

                                       b
                                                                                                                                                             p
                                                                                                                                                             b
                                                      DIAMETER OF DRAIN, INCHES
                                                                                                                                                      C5
                                                                                                                                                      m
                                                                                                                                                      -o
                                                                                                                                                      3>
                                                                                                                                                      TO
                                                                                                                                                       TO
                                                                                                                                                       -n
                                                                                                                                                       1—4
                                                                                                                                                       m
                                                                                                                                                       i—
                                                                                                                                                    GO O
                                                                                                                                                    I— I
                                                                                                                                                    M a
                                                                                                                                                    m TO
-C.


GO
-  o   o  o  o
O  CD   01  cn  4*
O  O   O  O  O
o  o   o  o  o
                                                    SMOOTH INTERIOR  PIPE

                                                      SLOPE FOR  n = O.O1 3
                                                O  O
                                                -  o
                                                O  00
                                                o  o
o o  o
o o  o
en ui  -c*
o o  o
         o  o
         o  o
         —  o
         O  03
                                                                                o o
                                                                                o o
                                                                                o o
                                                                                Ol Ul
      O
      o
      o
                                                                                                                                                             -n ^
                                                                                                                                                          II
                                                                                                                                                      GO
                                                                                                                                             O     O O
                                                                                                                                             -n o  I-N m
                                                                                                                                                •    TO
                                                                                                                                             -H O  O Z
                                                                                                                                             3: M  c: o
                                                                                                                                             m GO  r~ 2     ~n
                                                                                                                                                    "3> O     I-H
                                                                                                                                             3>     TO Cn     O
                                                                                                                                             33 >     73     c:
                                                                                                                                             2 Z  O 3>     »
                                                                                                                                             -< O  TO ~a     m
                       —  o  o o
                       o  CD  cn 01
                       o  o  o
                       O  O  O
                                          o   o
                                          O   o
o  o
o  o
01  cn
o  o
o  o
o  o
J  O
o  co
                                                                                                                       000
                                                                                                                       o  o  o
                                                                                                                       cn  cn  ^
                                                                       SLOPE FOR  n = 0.024

                                                             STANDARD CORRUGATED METAL  PIPE
                                                                                                                                       Z 3  Z ~n
                                                                                                                                       0-0
                                                                                                                                           II     73
                                                                                                                                       J>     ~n
                                                                                                                                       i-t O  f— O
                                                                                                                                       TO •   O O
                                                                                                                                          o  s: 2
                                                                                                                                       "n ro  >—i -o
                                                                                                                                       o -t*  z cr
                                                                                                                                       PD     cn —i
                                                                                                                                       O        (—i
                                                                                                                                                                       -£»
                                                                                                                                                                        I
                                                                                                                                                                       GO
                                                                                                                                                                C3
                                                                                                                                                      UD
                                                                                                                                                   I—  TO
                                                                                                                                                       m
                                                                                                                                                      /O
                                                                                                                                                                TO
                                                                                                                                                                m
                                                                                                                                                                o
                                                                            TH"
                                                                                  I  '   I   '   I1
                                                                                                                             i  i  i
                                                         VELOCITY, FT  SEC
                                                                                                                   p

                                                                                                                   CD
                                                                                                                           p

                                                                                                                           cn

-------
                                  TABLE 4-27

                   GUIDANCE FOR SUBSURFACE DRAINAGE SYSTEMS
a.  Rejected tiles should be broken so they will  not be used inadvertently
    elsewhere.


b.  Clay and concrete tile should not be stockpiled in contact with the
    ground.


c.  A minimum clearance of 50 ft should be maintained between drain lines and
    any trees and shrubs.  For water-loving trees such as willow, elm, cotton-
    wood and soft maple, this distance should be  increased to 100 ft.


d.  Soft or yielding soils which will serve as a  foundation for the drainage
    lines should be stabilized to protect the lines from settlement which
    could alter drainage gradients.


e.  All subsurface drains should be laid to line and grade and covered
    according to one of the methods outlined in Figure 4-43.  If anticipated
    future subsidence is predictable and small, grade may be adjusted to allow
    for same.


f.  Backfill should be placed in a manner that will not cause displacement of
    the drain.


g.  Laterals and mains should be bedded in a proper trapezoidal or circular
    groove (Table 4-28).


h.  The outlet should be protected against surface flow and an animal guard
    installed (Figure 4-33).
                                       4-94

-------
                             TABLE 4-28

               ALLOWABLE TRAPEZOIDAL* GROOVES FOR BEDDING
                 CORRUGATED POLYETHYLENE DRAINAGE TUBING
Nominal' Tube
Diameter (d)
(Inches)
4
5
6
8
4 & 5
4, 5, & 6
4, 5, 6, & 8
6 & 8
5, 6, & 8
Groove (d)
depth
(Inches)
1.1
1.4
1.7
2.1
1.5
2.0
2.8
2.4
2.5
Groove (Tw)
top width
(Inches)
4.1
5.1
6.2
8.0
5.1
6.2
8.0
8.0
8.0
Croove (B\v)
bottom width
(Inches)
1.8
2.3
2.9
3.7
2.1
2.3
2.4**
3.3
3.0
    *These trapezoidal  grooves with 45-degree side slopes will
    provide support  similar to that provided with a  circular
    groove shaped  to fit the lower 120°  of circumference.
   **The groove dimensions shown on this  line are for use with
    the semi-trapezoidal groove shown  below.  Bottom radius of
    curvature must be  6 inches or less.
                         r=radius of curvature
(Georgia,  n.d.; cited in Lee et al., 1984)

                                 4-95

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                FIGURE 4-32

   METHODS OF PLACING SUBSURFACE DRAINS
    METHOD 1

 Blinding
                        METHOD 2A
                                aterial
   METHOD 1A

 Blinding Material
                                       METHOD 3
                                    _	— ^
                                    "Blinding Material"1
                 METHOD 2

              ^'.T."^.-->x
              r  Filter' V. »':'*'; •
                        METHOD 4
•  .    -.
o~',' o ••" Material
• • «• .a v.* ;••
                      Envelope Material
Type of Conduct

1.  Flexible

2.  Flexible



3.  Rigid

4.  Rigid



5.  Flexible or  rigid
Special Conditions

Filter not  required

Filter required
a.  Prefabricated
b.  Sand  and  gravel filter

Filter not  required

Filter required
a.  Prefabricated filter
b.  Sand  and  gravel filter

Envelope  required
                                                      Method

                                                      1 or 4
                                                     1
                                                     2
                                                      1  or 3
                                                      1  or 3
                                                      4
                  (Georgia,  n.d.;  cited in Lee et al., 1984)

                    4-96

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                                  FIGURE 4-33

                              SMALL-ANIMAL GUARDS
(Georgia, n.d.;  cited in Lee et al., 1984)
much slower rate than drains using pipes, their usefulness should not be
overlooked.  At sites where a small amount of precipitation falls or where a
potentially damaging seep emerges and needs to be diverted, the drain tile may
be more than adequate and more cost-effective.  Specifications for drain tiles
are presented in Table 4-29.  A source of guidance for agricultural  drainage
practices is Van Schilfgaarde (1974).  Design factors in agricultural subsur-
face drainage are also discussed in Bouwer (1978).
    4.7.5 Exit Design
    A problem that is often overlooked and just as often causes problems is
the velocity and volume of the water in a drainage blanket at its lowest point
(its end).   This water may exit at too high a velocity if not intercepted
prior to exiting, and carry soil particles with it or cause a destabi1ization
of the slope at the toe of the drainage blanket.   An example of this problem
may be found in the discussion of the Sylvester hazardous-waste site in
Appendix B, "Case Histories."  Two methods of intercepting this water are the
toe drain (Figure 4-34) or installing a graded riprap filter.  Also refer to
Appendix H, "Outlet Structures."
4.8 Biotic Barrier
    Figure 4-1 shows a biotic barrier layer above the drainage layer and
beneath the surface layer.   The need for such a layer arises from the threat
of damage to the hydraulic barrier by intrusion of plant roots and burrowing
animals (sec.  4.6.2.3.).

                                     4-97

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                                   TABLE  4-29

                         GUIDANCE FOR TILE  SPECIFICATIONS
1.  Connections,  depth limitations, blinding,  backfilling, and  protection of
    the line  during installation should  be  in  accordance with local
    specifications.

2.  Joints:   Crack width for lateral tile  should vary with the  type  of soil:

    a.  Peat  and  muck - 1/4 inch preferred;  3/8 inch maximum
    b.  Clay  soils -  1/8 inch preferred;  1/4 inch maximum
    c.  Silt  and  loam soils - 1/16 inch  preferred; 1/8 inch maximum
    d.  Sandy soils - tightest fit possible.

3.  When the  tiles are laid in fine sand,  they should be turned as necessary
    to leave  the  least possible crack opening  and a filter should be provided
    to prevent the fine material from entering the tile.

4.  Crack opening for mains which serve  only to collect and transport drainage
    water from lateral tile lines should be  the tightest fit possible.

5.  Alignment.  A change in horizontal direction may be made by using one
    of the following  methods:

    a.  A gradual  curve of the tile trench on  a radius that the trenching
        machine can dig and still maintain grade.   Tile must be shaped or
        chipped so that no crack between tiles exceeds 1/8 inch unless the
        crack is  adequately covered to exclude soil movement to the  tile.
    b.  A manufactured or handmade bend  or fitting for small diameter tile.
    c.  A junction box or manhole for large  diameter tile.
                                   FIGURE 4-34

                                    TOE DRAIN
  DRAINAGE
  BLANKET
THICKNESS

      IMPERVIOUS SURFACE LAYER
                 DOWNSTREAM TOE DRAINAGE
                 TRENCH, MM. BASE
                 WIDTH * 3
                    MIN, DEPTH'4'

                             rcRFORATED,
                             CLOSED JOMT
                             DRAIN PIPE-
                          COAASE FILTER
                          FINE FILTER OR FILTER FABRIC
                                                          CLOSED DISCHARGE PIPE AT
                                                           INTERVALS .COLLECT OR PROTECT
                                                            DISCHARGE AT TOE.
                                              / •. • hDRAINAGE BLANKET,6 MIN. '-. • .':;
                                              -FINE FILTER AS REQUIRED, e"MIN.THIck OR
                                               ...•.•.•.....-.-..•..•. F|LTER FABR)c.
                                              HOMOGENEOUS PERVIOUS FOUNDATION
    Adapted  from  Department of the Navy,  1971

                                      4-98

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    As far as is known, such a layer has never been emplaced at an actual
hazardous-waste-site cover  installation.  It is therefore impossible to give a
proven working design.  It  is only possible to report some research results.

    Research at Los Alamos  National Laboratory and elsewhere has yielded a
rule of thumb for stopping  burrowing animals.  If objects in the animal's path
are too large for him physically to move and tightly enough packed, his prog-
ress is effectively stopped.  Thus a biobarrier can consist of cobblestones,
brick rubble, or any solid  pieces of inert material, as long as large air pore
spaces are present between  pieces.  This type of material also creates an
environment that plant roots cannot survive.

    Parry, Bell, and Jones  (1982) described a chemobarrier cover system de-
signed for an abandoned copper-smelter waste pile in England.  An 18-in.  cover
layer of an alkaline sodium carbonate waste (pH 9-12) was placed over the
metal-mining waste, followed by 6 in.  of topsoil.   A golf course was then
developed on the site.  The alkaline waste was used to inhibit plant-root
growth as well as to restrict mobility of metals from the smelter waste to the
topsoil surface.

    It has also been reported that root growth can be restricted by the place-
ment of a layer of material such as cobblestones (Cline, 1979), ground lime-
stone or pulverized fuel ash (Jones et al., 1982), or with root toxin such as
ureabor (Cline, 1979).

    In theory it is possible to design a "chemobarrier," that is, a layer of
high or low pH that is inhospitable to plant root penetration.   Examples of
chemobarriers are limestone (pH 8.5) and flyash (high alkalinity), or com-
pacted acid subsoil (pH 4.5).  Combinations of acid-tolerant vegetation and
an alkaline chemobarrier of flyash has potential in restricting root penetra-
tion into the waste.  Likewise calcareous-soil-loving vegetation combined
with a chemobarrier of a compacted extremely acid subsoil material has poten-
tial inhibiting root growth into the waste.

    These concepts are theoretically sound, but largely unproven.   The effect
of leaching the chemobarrier into the drainage system and out of the cover
system must be evaluated.    The most realistic present approach is careful
selection of short-rooted vegetation coupled with diligence in maintaining its
health.   This points up the importance of care in designing the vegetative
stabilization program, discussed in the next section.


4.9 Surface (Vegetative) Layer


    The surface layer is the one seen  by the eye and exposed to the elements,
which include rainfall and  snow.   This layer is subject to erosion,  and other
layers cannot be eroded until this one has been at least locally breached.

    In this Handbook the surface layer is called the vegetative layer,  because
vegetation provides the primary means  for controlling erosion,  while at the
same time promoting site aesthetics.   In any humid climate,  the surface will

                                     4-99

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inevitably become vegetated spontaneously,  in all  but rare circumstances
(e.g.,  at some mine dumps).   Thus,  it is not a question of whether or not to
vegetate, but rather one of having  controlled and  desirable vegetation, as
opposed to having an uncontrolled and possibly detrimental vegetative community
develop.

    An informative discussion of vegetation at landfill covers is presented by
Lutton, Regan, and Jones (1979).   Several  basic facts are pointed out by these
authors.   For one, sound and vigorous vegetation at landfill  sites is usually
highly cost-effective.   At the same time,  landfill sites pose several distinct
problems regarding vegetation.   Fertile soils are  rarely available at landfill
sites,  and it is necessary to work with the inferior soils that may be present.
An even more difficult problem is that a cover section designed to impede
percolation presents an environment that in many ways is the direct opposite
of one favorable to vegetation.   Because vertical  drainage is absent, roots
are subject to swamping.  Anaerobic conditions, detrimental to healthy roots,
may develop.   Conversely, cover systems designed to drain and dry quickly
deprive vegetation of needed reservoirs of moisture.   A drought, even a short
one, may kill or severely injure the vegetative community.

    For the reasons discussed above, the establishment and maintenance of a
stable vegetative cover are very challenging problems.  To meet them will
probably require a careful and possibly a sophisticated design.  Such a design
is not cheap.  Superfund guidance (see Chapter 1)  demands that cost-
effectiveness be emphasized.  Regarding stable vegetation a careful design
study is required, because cost-effectiveness in the long term will almost
surely be different from a minimal  first cost.

    The purpose of this section is to discuss general and specific considera-
tions regarding the use of plant materials adapted to the region in which the
waste site is located.   Much of the information herein has been drawn from an
instruction report that compiled existing vegetative data for restoration of
problem soil materials at Corps of Engineers construction sites (Lee et al.,
1984).   Guidance has also been drawn from an EPA manual for evaluating land-
fill cover designs (Lutton, 1982).


    4.9.1 Desirable Functions of Vegetation


    Vegetation shields the  soil surface from the  full  force of  impacting
raindrops, reinforces the soil against the hydraulic and  abrasive  action  of
moving surface water and wind, binds the soil particles together to  form  a
mass that is  less easily displaced, and anchors the  soil  in place.   Plant
leaves,  stems, and other aboveground portions of  vegetation,  as well as  the
organic  litter that collects on ground surface, can  also  shield the  soil
surface.  Only well-established vegetation,  however, can  perform all of  the
above  functions.

    The  vegetative  layer  should perform the  following  functions:
                                     4-100

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    •    Stabilize the soil against erosion by water and wind.

    •    Minimize percolation down to the waste.

    •    Maximize evapotranspiration of moisture from the soil material cover.

    •    Enhance the natural beauty (aesthetics) of the site and if possible
         develop basic recreational and related resources at the site.

    •    Create self-sustaining ecosystems of low maintenance.

    The first function is of major concern.   The other functions should be
considered to the extent possible.  All of these functions must be closely
linked to the long-term land-management objectives established for the specific
waste site.


    4.9.2 Soil Considerations
    Certain factors must be considered for any soil material to be used in the
vegetative layer of a cover system.  The major factors determining effective-
ness of a soil for supporting vegetation are grain size, pH, and organic-matter
and nutrient content.   A host of other factors play necessary though less
critical roles.   For a discussion of the influence of soil on vegetation the
reader is referred to Brady (1974).

    Fertile topsoil, if available for waste site cover, is usually cost-
prohibitive (Lutton, Regan, and Jones, 1979).   Consequently less fertile,
nonproductive soils or subsoils often have to be used.   Other cover materials
such as dredged material may be available.   A 3-ft cover of silty dredged
material was used successfully to vegetate and reclaim an acid surface-mine
land in Illinois (Spaine, Llopis and Perrier,  1978).   Dredged material  has
been used to improve the productivity of marginal, low-fertility soils  (Gupta
et al., 1978), as well as in solid waste management (Bartos, 1977).   Design
consideration for waste cover systems should be given to whatever soil  mate-
rials are locally available.  In addition,  waste materials such as sewage
sludge, manure,  or fly ash as a liming agent should be considered to improve
the fertility of the available soil materials.

    Appropriate tests can be conducted on the soils proposed for use in the
vegetative layer either at a State soil testing laboratory or at commercial
soil test laboratories.   An advantage in using State soil testing laborato-
ries is that their tests have been calibrated for local soil conditions with
extensive field testing to back up recommendations.

    Soil tests are available that can indicate if the soil material  is  acid,
saline and sodic, excessively drained, poorly drained,  or wind erodible or
contains dispersive clay (Lee et al., 1984).  Lutton (1982) recommends  that
the soil be examined according to the following sequence of factors, soil
tests being performed as necessary.


                                     4-101

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         4.9.2.1 Grain Size
    Soil composed of a mixture of clay,  silt,  and sand such that none of the
components dominates is called a loam.   The stickiness of the clay and the
floury nature of the silt are balanced by the  nonsticky and mealy or gritty
characteristics contributed by the sand.   A loam is rated overall best for
supporting vegetation as it is easily kept in  good physical condition and is
conducive to good seed germination and easy penetration by roots.

    Clay-rich soils may be productive when in  good physical condition, but
they require special management methods  to prevent puddling or breaking down
or cracking of the clay granules.   Silt-rich soils lack the cohesive proper-
ties of clay and the grittiness of sand,  are water retentive, and usually are
easily kept in good condition.  Soils made up  largely of sand can be produc-
tive if sufficient organic matter is present internally or as a surface mulch
to hold nutrients and moisture; sandy soils tend to dry out very rapidly and
lose nutrients by leaching.


         4.9.2.2 Soil pH


    Tests should be made to determine pH  and buffering capacity (usually
stated as tons/acre of calcium carbonate  ground limestone necessary to adjust
the soil pH to around 6.5).  The amount of lime necessary to neutralize a
given soil depends upon soil pore-water pH and "reserve acidity."  The reserve
acidity is a single factor which incorporates  several variables; soils with
high levels of organic matter and/or clay require higher amounts of lime for
pH adjustment.  The pH of subsoil  (where  appreciable in the cover) also in-
fluences lime requirements; acidic subsoils require higher levels and repeti-
tive applications of lime.  Some buried wastes act much like acid subsoils,
making higher lime-application levels or  more  frequent liming intervals neces-
sary for adequate pH control.


         4.9.2.3 Organic Matter and Nutrients


    Soil organic matter represents an accumulation of partially decayed and
partially synthesized plant and animal residues (Brady, 1974).  Such material
is continually being broken down as a result of the work of soil microorganisms.
Consequently, it is a rather transitory soil constituent and must be renewed
constantly by the addition of plant residues.

    The organic matter content of a soil  is small--only about 3 to 5 percent
by weight in a representative mineral topsoil.  Its influence on soil proper-
ties and consequently on plant growth, however, is far greater than the low
percentage would indicate.  Organic matter functions as a "granulator" of the
mineral particles, being  largely responsible for the loose, easily managed
condition of productive soils.  Also, it is a major soil source of two impor-
tant mineral elements, phosphorus and sulfur,  and essentially the sole source

                                     4-102

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of nitrogen.  Through its effect on the physical condition of soils, organic
matter also increases the amounts of water a soil can hold and the proportion
of this water available for plant growth.  Finally, organic matter is the main
source of energy for soil microorganisms.  Without it, biochemical activity
would come practically to a standstill.

    Soil organic matter consists of two general groups:  (a) original tissue
and its partially decomposed equivalents, and (b) the humus.  The original
tissue includes the undecomposed roots and the tops of higher plants.  These
materials are subject to vigorous attack by soil organisms, both plant and  •
animal, which use them as sources of energy and tissue-building material.

    The gelatinous, more resistant products of this decomposition, both those
synthesized by the microorganisms and those modified from the original plant
tissue, are collectively known as humus.   This material, usually black or
brown in color, is colloidal in nature.  Its capacity to hold water and nutri-
ent ions greatly exceeds that of clay, its inorganic counterpart.  Small
amounts of humus thus augment remarkably the soil's capacity to promote plant
production.

    Soil nutrients refer to chemical elements required by plants for their
growth processes.   Of the fourteen essential elements obtained from the soil
by plants, six are used in relatively large quantities and are thus referred
to as macronutrients (Brady, 1974).   They are nitrogen, phosphorus, potassium,
calcium, magnesium, and sulfur.   Plant growth may be retarded because these
elements are actually lacking in the soil, because they become available too
slowly, or because they are not adequately balanced by other nutrients.
Sometimes all three limitations are operative.

    Nitrogen, phosphorus, and potassium are commonly supplied to the soil as
farm manure and as commercial fertilizers.  They are called primary or ferti-
lizer elements.  In the same way, calcium, magnesium and sulfur are referred
to as secondary elements.  Calcium and magnesium are added to acid soils in
limestone and are called 1 ime elements.  Sulfur, other than that present in
rain water, usually goes into the soil as an ingredient of such fertilizers as
farm manure, superphosphate, and sulfate of ammonia, or is applied alone as
flowers of sulfur.

    Other nutrient elements (iron, manganese, copper, zinc, boron, molybdenum,
chlorine, and cobalt) are used by higher plants in very small amounts, thereby
justifying the name micronutrients or trace elements.  Such a designation does
not mean that they are less essential than the macronutrients but merely that
they are needed in small quantities.

    Table 4-30 indicates the range of concentrations of organic matter and the
three primary nutrients likely to be found in soils.   Results of soil tests
and reference to this table will indicate that a given soil rates low, medium,
etc., with regard to the substance tested for.   As indicated in the table, low
levels indicate the need for supplemental fertilization.   Local agricultural
county agents should be contacted to discuss soil fertilization requirements
in relation to local climatic conditions.
                                     4-103

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                                  TABLE 4-30

        RELATIVE LEVELS OF ORGANIC MATTER AND MAJOR NUTRIENTS IN SOILS
              (Bennett and Donahue, 1975; cited in Lutton, 1982)

Organic Matter,
Relative
Level3
Very low
Low
Medium
High
Very high
Sand,
Loamy
Sand
<0.6
0.6-1.5
1.6-2.5
2.6-3.5
>3.5
Sandy Loam,
Loam,
Silt Loam
<1.6
1.6-3.0
3.1-4.5
4.6-5.5
>5.5
percent
Clay Loam,
Sandy Clay,
Clay
<2.6
2.6-4.5
4.6-6.5
6.6-7.5
>7.5
Nitrogen
Ib/acre
<20
20-50
50-85
85-125
>125
Phosphorus
Ib/acre
<6
6-10
11-20
21-30
>30
Potassium
Ib/acre
<60
60-90
91-220
221-260
>260

 Medium level is typical of agricultural  loam soil.   Low levels need supple-
 mental fertilization; high levels need no fertilization under normal
 circumstances.
    Nitrogen is of special importance in establishing vegetation,  because it
is needed in relatively large amounts for vigorous growth but is easily
leached from the soil.   Nitrogen fertilizer requirements depend upon the
amount of organic matter present,  except for peat soil,  and the release of
nitrogen from the organic matter (higher organic-matter  levels requiring lower
application rates),  the soil  texture (more is required on sandy soils), and
the seed mixture chosen (more is required for grasses than legumes).   For
average soils 50 to  85 Ib/acre of  nitrogen is recommended.   Fertilizers are
rated by the amount  of nitrogen they contain per weight  of fertilizer (e.g.,
6 percent nitrogen).   To calculate the amount of fertilizer necessary to
furnish the recommended amount of  nitrogen, simply divide the recommended
application by the fractional amount of nitrogen the fertilizer to be used
contains.   For example, to apply 50 Ib/acre nitrogen using fertilizer con-
taining 6 percent nitrogen, divide 50 by 0.06 to get 833 Ib/acre fertilizer
required.   Table 4-30 indicates a  rough range of nitrogen levels present in a
typical loam with moderate levels  of organic matter.

    Customary levels of phosphorus in soil are shown in  Table 4-30.   Unlike
nitrogen,  phosphorus is less  mobile in the soil  and thus is lost very slowly
by leaching.   It is  possible  to give enough phosphorus in one application to
last several  growing seasons.  Generally at least 15 Ib/acre of phosphorus* is
recommended as a starter.   The availability of phosphorus to the plant is
quite dependent on pH.   At optimum pH values (6.2-6.8) amounts of 50 Ib/acre


aln calculating on the basis  of P205, percent P205 is 2.3 times an equivalent
 percent phosphorus; thus 34  Ib.  of P205 is required to  yield 15 Ib.  of ele-
 mental  P .
                                     4-104

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are usually adequate; at pH values below 6.2 or between 6.9 and 7.5, about
80 Ib/acre is needed for optimum growth.  Under very alkaline conditions (pH
greater than 7.5), phosphorus levels of 110 Ib/acre are required.   These
recommendations are for freshly excavated subsoils, or for sandy or high clay
soils of low organic material content.   See Brady (1974) for a detailed dis-
cussion of relations between pH and soil phosphorus.  Phosphorus is extremely
important for legume establishment.

    Potassium is much less important in grass establishment than in legume
establishment and maintenance; thus the rate of application depends upon both
soil test results and species to be seeded.  A minimum application of 26 lb/
acre potassium (32 Ib/acre K20) as a starter is recommended under any circum-
stances.  Applications can run as high as 230 Ib/acre potassium (277 lb/
acre K20) on impoverished soils where legumes are to be seeded.  Potassium is
moderately mobile in the soil and is slowly leached out, but one heavy appli-
cation should be adequate for several growing seasons.


    4.9.2.4 Thickness of Soil Layer


    The thickness of the surface vegetative-support layer is a matter of some
uncertainty.   Economics is an obvious inducement for the minimum tolerable
thickness, as there will be less material and placement cost.   However, the
thicker the layer the more stable it will be, and also the more likely to be
able to support desirable naturally deep-rooted plants such as legumes (dis-
cussed below).   The Resource Conservation and Recovery Act (RCRA)  specifies a
minimum surface-layer thickness of 2 ft for controlled landfill covers, and
this would seem to be a desirable minimum at uncontrolled sites as well.

    Among the factors to be considered is the need to retain enough moisture
in the surface layer to sustain vegetation through dry periods.  This question
was studied by Miller and Bunger (1963), who measured soil drainage behavior
in a sandy-loam soil layer of 2 ft minimum thickness underlain by more granu-
lar soils.  Their work showed that the sandy loam retained moisture better if
it was underlain by a free-draining layer than if it was continuous downward.
A "wick" effect seemed to be operative, suggestive that interruption of
capillary-type downward flow by the more granular layer served to  "trap"  the
moisture in the sandy-loam layer.


    4.9.3 Appropriate Vegetation


    Each species of grass, legume, shrub, or tree has its own environmental
and biological  strengths and limitations.  Moisture, light, temperature,
elevation, aspect, balance and level of nutrients, and competitive cohabitants
are all parameters which favor or restrict plant species.   The selection of
the best plant species for a particular site depends upon knowledge of adapted
plants that have the desired characteristics (Lutton, 1982).
                                     4-105

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    Guidance in the selection of appropriate plants for establishing vegeta-
tion on cover systems at waste sites is provided below.   Most of the detailed
information has been obtained from Lee et al.  (1984).   Supplemental  informa-
tion can be obtained from the sources given in Chapter 2.

    Plant growth regions are delineated in Figure 4-35 for the arid  and semi-
arid climates of the Western United States and in Figure 4-36 for the subhumid
and humid climates east of approximately the 100th meridian.   Plant  species
will be discussed and designated according to these plant growth regions.
Tables 4-31 and 4-32 list plant species that clearly have value and/or promise
for use on various waste cover systems in arid, semiarid, subhumid,  and humid
climates of the conterminous United States (Graham, 1941; Hafenrichter et al.,
1979; Clements, 1920; Martin et al., 1951; U.  S. Department of Agriculture,
1937; Mueller-Dombois and Ellenberg, 1974).  Additional information  for each
species is contained in Lee et al. (1984).

    Several considerations that are highly relevant in developing the vegeta-
tive layer of waste cover systems are:

    •    Criteria for selecting grasses and forbs

    •    Criteria for shrubs and trees

    •    Breeding and selecting plants for tolerance to stress

    •    Source of seeds

    t    Use of single species versus species in mixture

    •    Use of adapted native versus introduced plants

    •    Undesirable species


         4.9.3.1 Criteria for Selecting Grasses and Forbs


    The following criteria should be considered in selecting grasses and forbs
(herbaceous  nonlegumes and legumes) for the control of soil erosion and surface
runoff  (adapted from U. S. Environmental  Protection Agency, 1976):

    •    Availability in required quantity and  in  the appropriate season

    •    Rapid germination and development

    •    Ability to withstand the erosive and  traffic  stresses  present at  the
         site  being covered

    •    Adaptability to cover soil  conditions  (pH, texture, drainage, salin-
         ity,  sodicity, and  wind  erosion)
                                      4-106

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                             FIGURE 4-35
    PLANT  GROWTH  REGIONS  OF THE  ARID  AND SEMIARID AREAS OF
           THE WESTERN UNITED STATES (THORNBURG, 1979)
_£
_D_
Jl
                                                                           -10*00'
JL
_M_
 N
         LEGEND
Northern Great  Plains
Central  Great Plains
Southern Plains
Northern Rocky Mountains, Foothills and Valleys
Central  Rocky Mountains,  Foothills  and Valleys
Southern Rocky Mountains and  Foothills
Palouse  Prairie, Columbia Basin and  Plateau
Snake River Plain and Eastern Idaho
Great Basin Intermontane
Northern and Central Intermountain Desertic
Southern Plateaus
Cascade - Sierra Nevada
California Valley and Foothills
Southwestern Desert
                                                         'o
                                                         2
                                 4-107

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                                                  FIGURE 4-36
                 PLANT GROWTH  REGIONS OF THE UNITED STATES FOR THE HUMID AND SUBHUMID CLIMATES
                                     (U. S, DEPARTMENT OF AGRICULTURE, 1972)
o
00
    0  NORTHERN BLACK SOILS
    P  CENTRAL BLACK SOILS
    0,  SOUTHERN BLACK SOILS
    R  NORTHERN PRAIRIES
    S  CENTRAL PRAIRIES
    T  WESTERN GREAT LAKES
    U  CENTRAL GREAT LAKES
    V  OZARK-OHIO-TENNESSEE RIVER VALLEYS
    W  NORTHERN GREAT LAKES-ST.  LAWRENCE
    X  APPALACHI AN
    Y  PIEDMONT
    Z  UPPER COASTAL PLAIN
   ZA  SWAMPY COASTAL PLAIN
   ZB  SOUTH-CENTRAL FLORIDA
   ZC  SUBTROPICAL FLORIDA

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00
c
 i
co
Ul

(u
3
ft.
 I
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                                                                      TABLE 4-32

                                  CHARACTERISTICS AND SUITABILITY OF GRASSES RECOMMENDED  FOR  ESTABLISHING  GROUND  COVER






No.*
1

2


3

4


5

6

7

8

9

10

11
12
13







Common
Wheatgrass,
crested
Wheatgrass,
"Fairway"
crested
Wheatgrass,
thickspike
Wheatgrass,
standard
crested
Wheatgrass,
tall
Wheatgrass,
streambank
Wheatgrass ,
Siberian
Wheatgrass,
slender
Wheatgrass,
pubescent
Foxtai 1 , meadow

Bluestem, big
Blues tern, sand
Grama, sideoats





•o
Name £
Scientific
Agropyron cristatum

Agropyron cristatum,
var. "Fairway"

Agropyron
dasystachyum
Agropyron desertorum


Agropyron e long a turn

Agropyron riparium

Agropyron sibiricum

Agropyron
trachycaulim
Agropyron
trichophonm
Alopecurus pratensis
var. "Garrison"
Andropogon gerardii
Andropogon hallii
Bouteloua curtipendula

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Arid and
Humid Semiarid Season
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    •    Adaptability to climatic conditions (sunlight exposure,  temperature,
         wind exposure,  rainfall, drought) found at the site

    •    Tolerance to gases and organic decomposition products from buried
         waste

    •    Resistance to fire, insect damage,  diseases, and other pests

    •    Compatibility with the principles of secondary succession, and of
         land management objectives (Mueller-Dombois and Ellenberg, 1974)

    •    Compatibility with other plants selected for use on the same area

    •    Ability to propagate themselves (either by seed or vegetatively)

    •    Short- and long-term maintenance requirements and costs

    To minimize the possibility of failure in establishing an erosion-control
cover and at the same time reduce post-establishment maintenance requirements,
one must select grasses and legumes that are adaptable to the soil  conditions
found at the site.  This is especially important if the waste cover system
establishes an artificial soil profile.  For example, the use of an impermeable
layer over the waste can create a shallow perched water table in the overlying
soil profile.  A sloping cover system could result in the upper portion of the
slope drying out faster, while the lower portion of the slope would be wetter
for longer periods of time.  Consequently vegetation on the upper slopes will
need to be more drought-resistant, while the lower-slope vegetation will need
to tolerate prolonged wet periods.

    The possibility of marked differences in soil moisture regimes  within a
waste-site cover system should be given careful  consideration.  There are ways
to reduce the range of extreme soil moisture conditions across a waste site
(e.g., application of organic matter to the upper slope to retain more soil
moisture for a longer time period).  The information obtained during the
preliminary waste site characterization can indicate monthly rainfall distri-
bution and those plant species that have tolerated wet and dry soil moisture
conditions at the site.   These existing plant species will invade the cover
system and attempt to establish themselves in any area that has a suitable
soil moisture regime to which they are adapted.   Plant species observed in
wet areas surrounding the waste site will eventually colonize any wet areas
created in the cover system and having suitable soil conditions for growth.


         4.9.3.2 Criteria for Selecting Shrubs and Trees


    Since a major objective of the cover system is to isolate the waste from
percolating water, the use of shrubs and trees may have serious limitations.
There is insufficient information at present to indicate appropriate shallow-
rooted shrubs and trees.  Most shrubs and trees will extend their root systems
deep into the soil profile and can potentially penetrate any impermeable
barrier covering the waste.  The penetration of tree or shrub roots through

                                     4-116

-------
this protective barrier will allow water to percolate into the waste, which is
highly undesirable.  While chemobarriers (discussed in section 4.8) theoreti-
cally can be placed on the impermeable barrier covering the waste and should
inhibit shrub or tree roots from penetrating into the waste, these chemobar-
riers have not been adequately field tested on shrubs and trees.

    One application for which shrubs and trees might be considered is on the
side slopes of waste piles.  See for example the Kin-Buc Landfill in Appendix B,
"Case Histories."  On side slopes, impermeable membranes are inappropriate
because of the threat of sliding of the overlying soil.   Rill erosion, caused
by direct raindrop attack, is a problem on these slopes.   Ground-cover shrub-
bery, by intercepting raindrops, might minimize such erosion.  Some penetration
of the waste by shrubbery roots would occur, but owing to the steep slope, the
great majority of precipitated water will run off rather than enter the ground.

    Given these limitations, the following criteria should be considered in
selecting shrubs and trees for use in vegetative covers at waste sites (adapted
from McKell, 1975):

    •    Availability in needed quantity and appropriate time frame.

    •    Ability to produce shallow extensive root systems in order to exploit
         the entire layer of soil cover material for nutrients and moisture.

    •    Ability to become quickly established.

    •    Tolerance of acid, saline, sodic,  wet and droughty compacted (clayey)
         soil  environments.

    •    Compatibility with the principles  of secondary succession.

    •    Ability for vigorous growth after relief of moisture stress, and
         coppice formation and regrowth after physical  damage to roots/shoots.

    •    Ability to reproduce by natural  cloning and/or by seeds.

    •    Ability to create islands of soil  fertility by fostering an accumula-
         tion of organic matter, detritus,  and nutrients.

    •    Resistance to fire, insects, diseases,  animals and other pests.

    •    Compatibility with the erosion-control  grasses and legumes used to
         initially stabilize the cover.

    •    Tolerance to gases and organic decomposition products from buried
         wastes.

    •    Relative maintenance requirements  and costs.

    The permanent shrub and tree species that are finally selected must be
adapted to the soil conditions found at the site.


                                     4-117

-------
         4.9.3.3 Breeding and Selecting Plants to Tolerate Stress


    Perhaps the most effective strategy in establishing a stable vegetative
cover is the selection and genetic manipulation of plant species for tolerance
to various mineral  and associated stresses at a waste site (Baker,  1976).
Current thinking on the tailoring of plants to fit the soil  condition is that
soil  test calibrations are needed for selected plant species and cultivars, in
concert with the determination of those soil  limitations that may be economi-
cally modified or conditioned to permit the growth of plant species that have
been selected or bred for tolerance to various soil  conditions (Baker,  1976).

    Up to the present time, notable success has been reported in selecting
lovegrasses having tolerance to toxic levels  of soil aluminum (Foy et al.,
1980), in developing metal-tolerant varieties of red fescue and common  bent
(Smith and Bradshaw, 1972), and in the breeding and selection of barley varie-
ties having tolerance to very high levels of  salinity (Epstein, 1977).   Many
of the plant species listed in Tables 4-31 and 4-32 have been developed through
genetic manipulation and natural selection.  Those plant species have been
tailored or selected to thrive in the soil condition indicated.

    It is most critical that the soil cover environment be accurately known in
order to select the most appropriate plant species,  and appropriate rhizobium
species for legumes, for the site.


         4.9.3.4 Source of Seed


    Certified named varieties of adapted seeds should be used when available.
The source of adapted seeds should correspond to the SCS land resource  area
similar to that occupied by the waste site, and, in the southwestern United
States, not in excess of approximately 300 miles south or about 200 miles
north of the site.


         4.9.3.5 Use of Single Species Versus Mixtures


    Several factors influence the selection of a single species or mixtures.
These factors can include the degree of maintenance required, the desire  to
have the planting visually compatible with the surrounding vegetation and the
long-term planned use of the site.  Single grasses or mixtures of grasses
normally will require more maintenance nitrogen fertilizer than mixtures  of
grasses and legumes.  Legumes fix atmospheric nitrogen in their roots and
release the nitrogen in a form available to companion grasses  in the mixture.
The creation of nitrogen cycles  in derelict land has been successfully promoted
in Europe (Bradshaw et al.,  1982).  The application of these principles to
waste cover systems should be considered.  Legumes can readily accumulate
45-135  Ib N/acre annually  if provided with appropriate conditions (Bradshaw  et
al.,  1982).  The use of  legumes  in mixtures with grasses will  therefore reduce
the need and cost of expensive  supplemental nitrogen fertilizers.   In essence,

                                     4-118

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a self-sustaining vegetative cover could be established at the waste site.
While nitrogen needs can be satisfied with legumes included in grass mixtures,
there may still be a need for maintenance applications of lime and phosphorus
fertilizer to sustain a healthy vegetative cover if these materials are limit-
ing in the soil cover (Bradshaw et al., 1977).   Many legumes are deep-rooted
plants.   Consequently, caution must be taken to control deep root penetration
of the cover system into the waste material.   Use of a biotic barrier
(sec.  4.8) may be required to control legume root penetration.   Excellent
advice on grass-legume mixtures can be obtained from SCS plant material spe-
cialists and U. S. Forest Service reforestation specialists.


         4.9.3.6 Use of Adapted Native Versus Introduced Plant Species


    Native species should be given preference and used rather than introduced
species if they satisfy waste-site management objectives and can adequately
vegetate soil cover material used at the waste site.  This choice is valid for
waste sites so long as it is consistent with the major criteria listed earlier.


         4.9.3.7 Undesirable Species


    Care should be taken in not selecting herbaceous and woody species whose
growth habits are incompatible with the long-term management of the site, or
which, upon escape (i.e., as airborne seeds), inadvertently become undesirable
weeds in adjacent areas.   Nonweedy species that are adapted to the soil envi-
ronment at the waste site should be used (U.  S.  Department of Agriculture,
1973).  Potentially weedy plants should only be used in areas that are far
removed from prime farmlands.
         4.9.3.8 Other Selection Factors


    The following items should also be considered in plant selection:

    •    Potential fire risk of plant materials

    •    Adaptability to south-slope exposures versus north-slope exposures
         (aspect or exposure affects solar radiation loads, light quality,  day
         length, and growing season length)

    •    Presence of animals and birds that will  aid in seed dispersal (e.g.,
         some plant species are totally dependent on animals for seed
         dispersal)

    •    Adaptability of plant materials to habitats at increased elevations
         (generally, as elevation increases, the  length of the growing season
         decreases).
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         Adaptability of plant materials to any potential artificial soil
         profile effects within the cover system at the waste site (i.e.,
         perched water table).

    Grasses and forbs are the most effective plant materials for controlling
erosion.  Trees and shrubs are not very effective in controlling erosion in
the early stages because of their initial slow development.   But during the
middle and late stages of a developing vegetative cover system, the trees and
shrubs form a protective canopy and provide necessary buildup of surface
organic material (detritus and litter) which is excellent in controlling
surface runoff and erosion.   In addition, trees and shrubs can be beneficial
for screening, wildlife, and forestry purposes (Lee et a].,  1984).


    4.9.4 Establishment and Maintenance of Vegetation


         4.9.4.1 Time of Seeding and Planting


    An examination of waste site characterization information dealing with the
climatic region of the site and several years of temperature/precipitation
records will aid in determining the most favorable seeding and planting
periods.  This information can be related to the amount of time needed for
plant establishment.

    Baseline data will help indicate if a climatic region is subject to false
plant-growth starts;  for example, the region may have early  precipitation that
wets the soil and initiates seed germination, followed by a  long, dry period.
Of course this information will be very general, and weather conditions may
vary in the planting  year under study, thus causing a change in planting times
(U.  S.  Department of  Agriculture, Forest Service, 1979).

    Irrespective of the climatic region and the waste site,  the general rule
is to plant erosion-control  grasses and legumes immediately  ahead of the
highest expected rainfall probability.  Precipitation probability tables are
available for use in  the selection of a seeding date compatible with plant
growth (i.e., during  the frost-free times).  Additional assistance can be
obtained from the Plant Materials Specialists of the Soil Conservation Service
and local agricultural county agents in appropriate regions.

    Grasses and legumes used for vegetative covers are established by direct
seeding on a properly prepared seedbed.  Seeding application rates are given
according to State in Lee et al. (1984).  Annual species are quick to estab-
lish a cover and will be effective for one year.  Perennial  species should
also be mixed into the seed application.  They are slower to establish but
will continue regrowth year after year.  Woody plants, such as shrubs and
trees, are established by seedling transplants.  However, some woody species
can be seeded directly.  The soil material used for covering the waste site
should be analyzed to determine the proper lime and fertilizer requirements
according to the local State soil testing laboratory.


                                     4-120

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    If the optimum planting dates are exceeded because of extreme weather or
other conditions, the area should be seeded to one or more fast-growing annual
species such as wheat, rye grass, millet, rye, and grain sorghums.   Additional
information on specific considerations within each of the plant growth regions
can be found in Lee et al. (1984).
         4.9.4.2 Irrigation as a Temporary Measure


    Irrigation should be used only as a temporary measure to ensure the initial
establishment of herbaceous and woody vegetation in arid, semiarid, and sub-
humid regions.   Temporary irrigation can also be used to aid in leaching salts
from the saline soils found in arid, subhumid, and humid climates.   The amount
and frequency of irrigation depends on the availability of funds and labor,
the water requirements of the particular plant species, the amount  and inten-
sity of natural precipitation, and the chemical and physical makeup of the
soil materials at a specific waste site.   Details on the particular irrigation
and management practices for saline soils are presented in Richards (1969) and
U.  S.  Department of Agriculture, Forest Service (1979).


         4.9.4.3 Methods of Seeding and Planting


    Methods of seeding erosion-control vegetation on waste sites will  vary
depending on topography, type of vegetation,  stoniness of soil  surface, and
equipment availability.   Currently used seeding methods and their specific
suitability are:

    •    Hydroseeders are very useful for applying seed, fertilizer, and mulch
         on steep slopes and in other areas where equipment accessibility is
         1imi ted.

    •    Cyclone seeders are well  suited for broadcasting seed  on level areas.
         Germination can be increased by limiting equipment travel  over seeded
         areas.

    •    Grass or grain drills are limited to rolling or level  terrain that is
         relatively free of stones.   The Rangeland drill is sturdier than
         conventional drills and provides better and longer performance on
         critical  area soils.

    •    Rear-mounted blowers can  be attached to lime trucks to spread both
         seed and fertilizer on steep slopes  and other inaccessible areas.

    •    Sprigging is used for certain grass  species to establish vegetative
         cover more rapidly than would be possible using seed.

    •    Hand planting generally is used when bare-root seedlings of trees and
         shrubs are planted.   The  method is time-consuming and  therefore
         costly.

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    (1) Arid and semiarid climates.   Seeds may be planted by either drilling
or broadcasting, but under semiarid and arid conditions drilling is recommended
for the following reasons:

    •    The seed is covered to a proper depth and protected from the
         environment

    •    The seed is uniformly distributed

    •    Rate of seeding is controlled

    •    Soil firming can be done with the packer wheels attached to the drill
         (U. S.  Department of Agriculture, Forest Service, 1979).

    In arid and semiarid climates, broadcasting is considered less efficient
because the seeds often perch on top of the soil  where germination and estab-
lishment are difficult, if not impossible.  Rodents and birds may pick up
broadcast seeds and eat them or carry them away to a seed cache.   When seed is
broadcast the soil  should always receive some mechanical treatment to give
suitable seed coverage, unless the bed is loose so that the natural sloughing
of soil will cover the seed.   Planting should be  done on the contour to trap
available moisture and prevent erosion (Lee et al., 1984).  Numerous types of
drills and broadcasters are on the market for use in arid regions.   Selection
of specific equipment will depend on their availability, capability, charac-
teristics of the site, and treatment required.   Further details on drills and
other equipment for arid and semiarid regions are listed in U.  S.  Department
of Agriculture,  Forest Service (1979).

    (2) Humid climates.  A good seedbed is essential for the successful estab-
lishment of seeded vegetation, both herbaceous and woody.   Except for the
winter period,  an ideal situation is to seed the  soil immediately after grad-
ing, thereby taking advantage of a ready-made seedbed.   For preparing a seed-
bed, "front blading" with a bulldozer provides some advantage over "back
blading" because of impressions left in the soil  by the dozer tracks provide
microsites that favor seed germination and seedling establishment.   However,
with either method of grading, it is best to seed immediately after the grad-
ing, because most cover soil  materials will crust over or harden after they
are rained on and dry out (Lee et al.,  1984).

    There is no "best" method for applying seed.   The main requirement is that
the seed be evenly distributed on a good seedbed.   The hydroseeder is widely
used and desirable because it can place seed on outslopes and highwalls where
most other types of seeders cannot reach.   The term hydroseeding means the
hydraulic application of a slurry of plant seeds  and water to problem soils.
However, for seeding benches and leveled areas, a cyclone seeder or a grass
drill can be just as effective.  In fact, spreading seed "dry"  has some advan-
tages in that the entire load in the seeder is payload and not  mostly water as
with the hydroseeder.  Dry-mixing seed and fertilizer together  and spreading
with a conventional lime-spreading truck is an efficient method for covering
large areas.  The Estes One-Way Blower attached to lime trucks  increases their
versatility and "reach" on large areas.  Some problem may occur in calibrating
the rate of dispersal so that both seed and fertilizer are applied at about

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the proper rates.  However, this equipment has been successfully used for
seeding and fertilizing strip mines in eastern Kentucky.

    Soils that are free of stones and level enough for use of farm equipment
may be seeded with a grass or grain drill.  One advantage of using a drill is
that all of the seed is placed in the soils and covered.   Thus, less seed is
needed because most of the seed is placed in a microenvironment that favors
germination and seedling establishment.   Tillage or scarification of a seedbed
usually is not necessary prior to seeding with a drill.

    Details for planting shrubs and trees in humid climates are given in Lee
et al.  (1984).  Additional information can be obtained from the USDA, Forest
Service and State Forestry Departments.


         4.9.4.4 Mulching and Chemical Stabilization


    Mulching and chemical stabilization are two major types of short-term, or
temporary, nonvegetative soil stabilization.  Both are employed to provide
protection against excessive soil erosion for periods of less than one year.

    Mulching is essential on most waste cover soils and especially on slopes
steeper than 3:1.  Figure 4-37 illustrates the relationship between surface
slope and potential for soil erosion.

    The application of plant residues or other suitable mulch materials to the
soil surface functions to:

    •    Prevent erosion, both by water and wind

    •    Prevent surface compaction or crusting

    •    Facilitate infiltration

    •    Inhibit evaporation (which may also slow upward movement of salts
         through soils)

     •    Provide proper soil temperatures

     •   Be compatible with plant development, improve germination conditions,
         protect seedlings

     O   Possibly add desired seeds while acting as a mulch

     •   Reinoculate microorganisms into excavated materials

    The effectiveness of any mulch depends upon many factors, including the
physical and chemical properties of the soil, the land-forming or cultural
practices, species to be seeded, and the characteristics of the mulch itself,
such as its color, roughness, and manner of application (Lutton, Regan, and
Jones,  1979).   The effect of color and roughness are directly related to the

                                     4-123

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                                     FIGURE 4-37
                        INFLUENCE OF  SLOPE ON REVEGETATION
                    (FROM NEVADA STATE  CONSERVATION  COMMISSION)
                                                     Severe erosion hazards zone
                                                     Revogetation improbable
                                 Critical erotion hazards
                                 Revegetatlon success poor
               Moderate erosion hazards zone
               Revegetalion success lair
         Moderate erosion hazards
         Revegelatfo
            Moderate erosion hazards zone
            Revegetation success very good
                 Slight erosion hazards zone
                / Slope influence minimal
radiation  balance at the  soil  surface and,  consequently,  the heat transfer
into and out of the soil.   Slope and orientation of the  soil surface also
influence  the solar energy input.   Other  factors determining mulch efficacy
are steepness and length  of slope, soil texture and depth,  rate of application
of mulch,  and the weather before,  during,  and after mulch application.   Selec-
tion depends upon characteristics  of the  area to be stabilized and the  avail-
ability, cost, and properties  of the mulch  material (Lutton, Regan, and Jones,
1979).  Several of the more common and effective mulches  and their applications
are listed in Tables 4-33 and  4-34 (Lee et  al., 1984).
          4.9.4.5 Organic  Mulches
    Mulches  of organic materials such as  straw,  hay, woodchips,  wood fiber,
and other  conventional short-term materials  are  the most popular means  of
providing  short-term soil  stabilization.   Mulch  is used in  the establishment
of a vegetative ground cover to protect the  seedbed from excessive erosion
prior to germination of the  seeds and until  the  new vegetation is sufficiently
                                       4-124

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                                                          TABLE  4-33
                    GUIDE  TO  SHORT-TERM  MULCH  MATERIALS,   RATES,   AND  USES
    Mulch
   Material
Sawdust, green
or composted
Free from objec-
tionable  coarse
materials
                                     Application
83-500
cubic
feet
                                                                               Disadvantages
                                                                                                           Remarks
Protects  surface       Shavings and sawdust blow

Adds organic matter    Nitrogen deficiency

No weed seeds          Packing may occur re-
                      sulting  in less aeration
More fire resistant
than straw            May float on running
                      water
Long lasting
Mood chips




Wood excelsior




Wood fiber
eel lulose
(partly di-
gested wood
fibers)


Compost or
manure



Cornstalks or
sorghun stover,
shredded or
chopped
Grass hay or
gram or straw




Green or air
dried. Free
from objection-
able coarse
materials
Green or air
dried burred
wood fibers
.024" x .041"
x 4"
Usually dyed
green. No
growth organism
inhibi ting
factors. Air
dried 30% fibers
3.7 mm
Well shredded,
free from exces-
sive coarse
material

Air dried,
shredded into 8"
to 12" lengths

Air dried, free
from undesirable
seeds and coarse
materials


500-900
Ibs.



90 Ibs.
(1 bale)



25-30
Ibs.





400-600
Ibs.



150-300
Ibs.


75-100
Ibs.,
2-3
bales


10-15 2"-7"
tons



2 tons




1000-
1500
Ibs.




8-10
tons



4-6
tons


1.5- Lightly
2.5 covers 75
T. to 90% of
90-120 surface
bales

Easy to apply May prevent precipitation
from reaching spoil
Chips resistant to
wind movement













Can protect soil When used alone, it be-
surface and adds comes wet, then dry,
nutrients, such can lose much of N
as N, P, K, S through volatilization
of ammonia




Generally most Weed seeds usually pre-
economical sent; even hay seeds may
be considered a weed on
Usually satisfactory a particular site
under many
circumstances Straw may "wick-out"
                                                                                         moisture from soils  in
                                                                                         very dry conditions,
                                                                                         thus resulting in  poor
                                                                                         germination and seedling
                                                                                         establishment
 In situ mulches
 (cereal grains
 or sunnier
 annual  crops
 like wheat,
 barley, or rye)
                                                    Produces quick cover
                                                    to  stabilize dis-
                                                    turbed areas.  Pro-
                                                    vides uniform mulch.
                                                    More economical  than
                                                    artificially applied
                                                    mulching materials.
Most effective as a
mulch around  ornanen-
tals, snail fruits, and
other nursery stock.
Special  application
rates - fruit trees
5-7"; vegetables and
flowers 2-3"; blackber-
ries and raspberries
4-7"; striwherrips 3".
Good resistance  to wind
blowing.  Requires 30-35
Ibs. N/ton to prevent N
deficiency while decay-
ing mulch. One  cubic
foot weighs 2$ pounds.
Has about the sane use
and application  as saw-
dust, but requires less
N/ton {10-12  Ibs.).
Resistant to  wind
blowing.  Decomposes
slowly.

Effective for erosion
control.  Tie-down
needed on windy  sites.
Decomposes slowly.
Packaged  in 80-90 Ib.
bales.
Men used for erosion
control on critical
areas double  aopiication
rate.  Apply  with hydro-
nulcher.  Mo  tic-down
required.  Packaged  in
100 Ib. bags. Has not
been very satisfactory
for establishing seed-
ings on arid  sites.
Use a strawy  manure  when
erosion control  is
needed.   May  create
problems  with weeds,
Excellent noisture
conserver.  Resistant to
wind blowing.
Effective for erosion
contro1,  relatively  slow
to decompose. Excellent
for pi'ilch crop on
fields.   Mas  about  the
same value as a  cover
crop.   Resistant to  wind
blowing.
Use straw where  nulch
effort  to be  maintained
for nore  than 3  nonths.
Subirct to wind  blowing
unless  kept noist or
tied down.  Most common
and widely used  nulchino
material.  Good  for  ero-
sion control  in  critical
areas.  Anchor mulch,
especially on slopes  by
crinping, or  using  plas-
tic meshes, jute, chen-
ical tackifiers. Long-
stemmed best, especially
for crimping. Uniform
application important.
Can be  spread with modi-
fied fam manure
spreader.
Fall crops killed with
herbicides in spring
before  maturity, sumer
annuals killed by frost
in fall.  Interseed  with
permanent grasses and
legumes species.  Pro-
duces up  to ?.*i  Txac  dry
matter.
                                                                                                                                 (continued)
                                                               4-125

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                                                   TABLE  4-33   (continued)
    Mulch
   Material
Mats t Netting:
    Quality
   Standards
Twisted kraft
paper yarn
Twisted kraft
paper yarn
Jute, twisted
yarn
Plain weave,
warp 7 per inch,
filling 4 per
inch selvage
edge with
polyproplyene
filament
Fungicide treated
warp 1.1  pairs/
in. filling
2.5/in.
Undyed, un-
bleached plain
weave.  Uarp 78
ends/yd.  Heft
41 ends/yd
 Plastic
                 2-4 mils
  Unit
  Size
Unit 4
Weight
  Area
 Covered
 Per Unit
                                                        Advantages
                                                                    Especially useful on
                                                                    steep slopes

                                                                    Nets good in high
                                                                    wind areas
                                                                                Disadvantages
                                                                          Expensive:   4-5 times
                                                                          more than tacked straw

                                                                          High labor input for
                                                                          anchoring
                                                                          Not effective on rough
                                                                          surfaces or rocky areas
                                                                          Erosion from beneath
                                                                          may be a problem
 45"
x 250
yds.
 45"
x 250
yds.
 45"
x 50
yds. or
48" x 75
yds.
Roll
100
Ibs.
Roll
60
Ibs.
312H sq.
yds.
312)s sq.
yds.
Roll     60 sq.
60 Ibs.  yds.
90 Ibs.  100 sq.
         yds.
 Excelsior wood   Interlocking web     36"
 fiber mats       of excelsior       x 30
                 fibers w/mulch     yds.
                 net backing on
                 one side only.
                                              Roll
                                      yds.
                                                           sq.
                                    Variable
                                    up  to  50'
                                    wide
                                                    Excellent vapor
                                                    barrier
                                                    Good weed control
                                                    Light colored,  per-
                                                    forated, found
                                                    effective in New
                                                    Mexico:  soil tem-
                                                    perature in summer
                                                    18°F lower than  in
                                                    soil .with no nulch
                                                        Labor intensive
                                                        High cost
                                                                                                              Renarks
                                                                                   Used only on 1imited
                                                                                   critical areas  because
                                                                                   of cost.
Used to hold  seed  and
afd in gemination with-
out mulch.   Tie  down
according to  manufactur-
ing specifications.  Not
effective in  seeding
establishment on arid
sites.  Lasts about one
year.

Use over bare soil or
sod to prevent erosion
and hold seed.  Good  for
waterways and critical
ditch bottoms.  Tie down
with staples  as per man-
ufacturing  specifica-
tions and on critical
areas.  Lasts about one
year.

Use without additional
mulch.  Tie down as per
manufacturing specifica-
tions.  Effective for
erosion control  in
waterways and ditches.
Lasts about one year.

Use without additional
mulch.  Tie down as per
manufacturing specifica-
tions.  Good for estab-
lishing seedings on
critical areas.

Use black for weed con-
trol , use white for
seeding establishment
without organic mulch.
Release plastic after
seeding is established.
Information on tempera-
ture effect varies.  The
materials allow air and
water  interchange but
prevent evaporation of
soil moisture.  Usually
must be renewed each
season.  Some users
place a 1" layer of sand
underneath to prevent it
from tearing when
stepped upon,  fust be
punctured with frequent
small  holes for penetra-
tion of air and water
and weighted down around
edges.
 aAll mulches will  provide some degree of erosion control, moisture conservation, weed control,  and  reduction of soil crusting.
                                                                   4-126

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                                                 TABLE 4-34

                                            MULCH ANCHORING GUIDE
Anchoring Method
  or Material
Kind of Mulch to be Anchored
                      How to Apply
MANUAL

Peg and twine
Mulch netting
Soil and stones
Silt
MECHANICAL

Asphalt spray
(emulsion)
Wood cellulose
fiber

Pick chain
Hay or straw, pine straw,
corn stalks
Hay or straw, shredded sugar
cane, pine straw, compost,
wood shavings, tanbark, corn
stalks

Plastic
Hay or straw, corn stalks
Compost, wood chips, wood
shavings, hay or straw
Hay or straw
Hay or straw, manure compost,
pine straw
Mulch anchoring      Hay or straw, manure, pine
tool or disk         straw
(smooth or notched)
Chemical
Hay or straw
Sheepsfoot roller    Hay, straw, manure, corn
or packer            stalks
After mulching, divide areas into blocks appro. 1 sq.
yd. in size.  Drive 4-6 pegs per block to within 2" to
3" of soil surface.  Secure mulch to surface by
stretching twine between pegs in crisscross pattern on
each block.  Secure twine around each peg with two or
more turns.  Drive pegs flush with soil where mowing
and maintenance is planned.

Staple with lightweight paper, jute, wood fiber, or
plastic nettings to soil surface according to manufac-
turer's recommendations.
Plow a single furrow along edge of area to be covered
with plastic, fold about 6" of plastic into the furrow
and plow furrow slice back over plastic.  Use stones to
hold plastic down in other places as needed.

Cut mulch into soil  surface with square-edge spade.
Make cuts in contour rows spaced 18" apart.
Apply with suitable spray equipment using the following
rates:  asphalt emulsion 0.04 gallons per sq. yd.;
liquid asphalt (rapid, medium, or slow setting) 0.10
gallons per sq. yd.
Apply with hydroseeder immediately after mulching.
750 Ibs. wood fiber per acre.
                   Use
Use on slopes steeper than 3:1.
with suitable power equipment.
Pull  across slopes
Apply mulch and pull a mulch anchoring tool over mulch.
When a disk (smooth) is used, set in straight position
and pull across slope with suitable power equipment.
Mulch material should be "tucked" into soil surface
about 3".

Apply Terra Tack II (45 Ibs.) or Aerospray 70
(60 gal/A.) according to manufacturer's instructions.
Avoid application during rain.  A 24-hour curing
period required and soil temperature higher than 45°F.

Pull sheepsfoot roller over the areas after mulch is
applied.  Can be operated up and down the slope.
                                                   4-127

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established.   The mulch provides a favorable environment for seed germination
and plant development.   Mulches can also be used in place of short-term vege-
tative stabilization to protect temporarily against excessive soil  loss prior
to the preparation of a seedbed.

    Water-dispersible mulching materials and tacks are used for hydroseeding
operations.   The most frequently used mulching materials (singly or in various
combinations) are wood-cellulose fibers; a 50-50 mix of ground newsprint and
corrugated papers (decontaminated of borates); various powdered gums;  liquid
styrene-butadiene copolymer emulsions; and defibered grass or cereal  straws
(Kay, 1979;  U.  S. Environmental Protection Agency, 1976).

    In hydroseeding, fertilizers, limestone, mulch materials, and chemical
tacks and binders may also be present in the pumped slurry, along with the
seeds.  Chemical stabilization is discussed in the following section.   Com-
parison of certain water-dispersible mulches and stabilizers is shown  in
Table 4-35.   According to Bradshaw and Chadwick (1980) the wood cellulose
fiber ranks  equally to jute netting for soil stabilization and to straw mulch
for level of persistence.

    The term hydromulching applies only when a water-dispersible mulch mate-
rial is hydraulically spread onto a cover soil material (Kay, 1978; U. S.  En-
vironmental  Protection Agency, 1976; U.  S.  Department of Agriculture,  Forest
Service, 1979).   Table 4-36 summarizes information on hydroseeding and hydro-
mulching experience in the state of California.   The cost and effectiveness of
hydroseeding/hydromulching varies.  Alternative methods should be considered,
since the most expensive approach is not necessarily the most effective.
According to Kay (1978) "straw plus tackifier is more effective for both ero-
sion control  and plant establishment than many of the more expensive treat-
ments" (see  Table 4-35).  Under some conditions, having a rough seedbed or
covering the seed may be the best approach to establishment of protective
vegetation (Kay, 1978).

    The most important consideration for any hydromulching material is that it
must stick to the soil and hold the seed on steep slopes against high  wind  and
rainfall intensities (Kay, 1978).  But it is equally true that these same
qualities may prevent the seed from readily falling into natural depressions
(microsites) and becoming covered with soil, thereby promoting a higher stand
density (Kay, 1978).

    Another problem arises when the germination of legume seeds is inhibited
by fertilizers containing moderate to high concentrations of certain soluble
salts (e.g.,  ammonium sulfate and sodium nitrate) in the slurry.  When the
fertilizers were omitted from the slurry the germination of hydroseeded legume
seeds was excellent (Bradshaw and Chadwick, 1980).

    The problem of seeds failing to fall into microsites could best be re-
solved by first broadcasting or drilling the seed, followed by the application
of a quality hydromulch (Kay, 1978, p. 6).  For the problem of fertilizer
inhibition of legume seed germination, the recommended solution was to apply
the mineral  fertilizer three to six weeks after the initial hydroseeding
(Bradshaw and Chadwick, 1980).  Other factors generating concern in

                                     4-128

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                                                 TABLE 4-35
            COMPARISON OF UATER-DISPERSIBLE MULCHES AND STABILIZERS FOR INITIAL LAMD RESTORATION
                                 (Modified from Bradshaw and Chadwick, 1980)


flaterial
Stabil izer/mulches
Uood cellulose fibre
(as slurry)
Sewage sludge
(as slurry)
Stabilizers
Asphalt
(as 1 :1 enulsion)
Latex
Application
Rate3
(Ibs/acre)

890-1780

1780-3560


670

178


Persistence

OO

o


o

o


Stabilization

ooo

00


00

OO
Soil
Moisture
Retention

O

O


o

o


Nutrient Toxicity

o o

O o


o 0

o OO
Asphalt
(as 1 :1 enulsion)
Latex
(as appropriate
enulsion)
Alginate or other
colloidal carbohydrate
(as emulsion)
Polyvinyl acetate
(as 1 :5 enulsion)
Styrene butiadene
(as 1 :20 enulsion)
670

178


178


890

446

O

o


OO


OO

CO

00

OO


OO


OO

OO

o ° o

o o OO


o o o


o o oo

o o OO

OOO high;     OO moderate;     O low;
o nil
 a  Rates can  be  varied  depending on circumstance-will affect soil water capture and retention and seeding
   establishment

-------
                                                TABLE 4-36
               SUMMARY OF METHODS AND COSTS OF HYDROSEEDING AND HVDROMULCHING IN CALIFORNIA
                                         (Adapted from Kay, 1976)
        Treatment
                                             Comments
                                                                         Preger-
                                                                         mination
                                                                         erosion
                                                                         effect-
                                                                         iveness
                                                                                    Effective-
                                                                                     ness on
                                                                                      plant
                                                                                    establish-
                                                                                      ment3
                                                                     Approx.
                                                                      cost
                                                                      per  h
                                                                     acre $b
1.  Hydroseeding or hydro-   Similar  effectiveness  to  broadcasting seed       1         1-4          250
    mulching (seed + fer-
    tilizer) with 500 Ib
    wood fiber, 1,500 gal
    water/3 acres.
2.  Hydromulching with       The  addition  of  an  organic  qlue will  some-       2+        3-6         550-650
    1,500 Ib wood fiber
    plus an organic glue:
    Ecology Control,
    Terratack III etc.
    plus seed and
    fertilizer.

    Hydromulching with       Produces a  true  mulch  effect and  some ero-       2-3       4-7         530-750
    2,000-3,000 Ib/acre
    wood fiber plus seed
    and fertilizer.
    Seed and fertilizer      Very effective,  combines  advantages  of           2-3       6-8         680-865
    broadcast and covered
    with soil but followed
    with hydromulch of
    wood fiber at 2,000-
    3,000 Ib/acre.

All of the above treatments offer only minimal  protection from impact of raindrops  and  water  flowing  over
the surface, but all are weed free.
3.
4.
                             Similar effectiveness to broadcasting seed
                             and  fertilizer.  Not enough  fiber to hold
                             seed  in place or produce a mulch effect.
                             Seed  distribution would be improved by  in-
                             creased volume of water.
                             The  addition of an organic glue will some-
                             times  improve fiber holding  and
                             germination.  Does not  increase labor or
                             machinery  cost.
Produces a true mulch effect and some ero-
sion protection.  Commonly better results
than 1,000 Ib fiber or fiber plus glue.

Very effective, combines advantages of
seed coverage and mulching.
5.  Straw or hay broadcast
    with straw blower on
    the surface at 3,000
    Ib/acre and tacked
    down (asphalt emul-
    sion, Terratack II,
    etc.).  Seed and
    fertilizer broadcast
    with hydroseeder or
    by hand.

6.  Straw broadcast 4,000
    Ib/acre rolled to in-
    corporate (punched)
    another 4,000 Ib straw
    broadcast and rolled,
    seeded and fertilized.
    Seed and fertilizer
    broadcast with hydro-
    seeder or by hand.
7.  Roll-out mats (jute,
    excelsior, etc.).
    Held in place with
    wire staples.  Seed
    and fertilize as  in
    No. 1.

8.  Seed and fertilizer
    broadcast, or hydro-
    mulched with fiber
    (treatment), followed
    by  erosion control
    chemical such as  poly-
    vinyl  acetate at  6:1
    dilution (6 parts
    water)  at  1,000  Ib
    solid/acre  (approx.
    200 gal. PVA).
                             Common elsewhere in U.  S.   Very effective        5-7
                             as energy absorber, mulch;  and straw forms
                             small  dams to hold some soil.   May be
                             weedy  depending on straw source.   Not for
                             cut slopes steeper than 2:1.   Cost would
                             increase significantly  if slopes  over 50
                             feet from access, or application  is
                             uphill.
                             Common difficult fill  slopes in California      6-8
                             very effective.  Not possible on most cut
                             slopes.  Very weedy.  Cost would increase
                             significantly if slopes over 50 feet from
                             access.
                             Some are a good mulch, weed free, adapted       5-7
                             to small areas.  Can be installed any
                             season, cuts or fills.  Unsightly.  Diffi-
                             cult to install on rocky soils.
                             Very expensive, but will hold soils and         10+
                             seed in some very difficult conditions.
                             May restrict penetration of water into
                             soil.  Will not cure below 55°F.  Not
                             effective on soils which crack.  Will not
                             cure below 55°F.  Not effective on soils
                             which crack.  Will not support animal or
                             vehicle traffic.
                                                                                                     650
                                                                      877-1070
                                                                                        5-10
                                                                                                  2400-2700
                                                                                                  1070-1370
 al  = minimal, 10 = excellent.

 Assumes  seed plus fertilizer  $150.00,  fiber  $150/ton,  Ecology Control $1.25/lb., PVA $3.00/gal ,
  1,500 gal  hydroseeder  with  2  man  crew  $55.00/hr, labor $13/hr, straw $50/T, straw mulcher with
  4  man crew $64/hr (applies  2  T/hr)  and markup of 30% for overhead  (including equipment depreciation),
  and profit.
                                                    4-130

-------
hydroseeding/hydromulching practices are as follows (U.  S.  Department of
Agriculture, Forest Service, 1979; Bradshaw and Chadwick, 1980; Kay, 1976 and
1978):

    •    Often an expensive and unreliable technique

    •    Hydromulches may improve germination but do not improve stand density
         compared to drilling followed by mulching

    •    Additional nitrogen may be needed to compensate for the wide carbon:
         nitrogen ratio of the chosen mulch material

    •    Success or failure of hydroseeding may depend on getting a good
         legume stand; the presence of nitrogen-fixing legumes is a must for
         long-term low-maintenance vegetative covers.

    •    Hydroseeding and hydromulching should be used in special situations
         such as areas that are too inaccessible or steep for conventional
         seed drills and other equipment and in those areas where the seed can
         be kept moist for two to three weeks after seeding.

    •    Increased rates of application of water, seed,  wood fiber, and chemi-
         cal tack/binder may lead to prohibitively high costs of erosion
         control for soil covers on waste sites in arid and semiarid regions.

    •    Direct-seeded shrubs and herbaceous plants often do not withstand the
         competition from grasses used in the seeding mixture for erosion
         control during the initial stabilization phase.

    •    Some wood fiber and paper hydromulches may require measures to remove
         boric acid, borate, and other potential soil  sterilants (U. S.
         Department of Agriculture, Forest Service, 1979; Bradshaw and
         Chadwick, 1980; Kay, 1978).

    On extremely acid cover soils the order of 4 to 5 tons per acre of lime
material is required; about half of this amount can be applied at one time in
the hydroseeder, making it necessary to spread the additional lime separately
(Bradshaw and Chadwick, 1980).

    The capacity ranges for hydraulic seeding/mulching machines are between
150 and 1500 gal.   Volumes of water required per acre also range from 150 to
1500 gal.   The amount of wood fiber required per acre may range from 500 to
3000 Ib.  Recently, Kay (1978) has reported that the effectiveness of wood-
fiber mulch in controlling erosion and enhancing plant establishment was
doubled when the wood-fiber application rate was 3000 Ib/acre, compared to
conditions where the seed and fertilizer were broadcast and then covered with
soil in the absence of wood-fiber mulch.   The approximate cost of the latter
treatment was $320 per acre, while the addition of the wood from hydromulch
treatment raised the cost to $865 per acre (see Table 4-36).  However, it was
shown that the pregermination erosion control effectiveness was increased
threefold by use of wood-fiber mulch.


                                     4-131

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         4.9.4.6 Chemical  Mulches and Stabilizers
    Some treatments include the use of short-term erosion-control  chemical
binders and tacks in combination with conventional  mulches and water-
dispersible mulches (Kay,  1976).   Current information on the cost-effectiveness
of chemical tacks and binders under a wide range of environmental  settings  is
limited.  General information on chemical binders and tacks is given in
Tables 4-37 and 4-38.

    Chemical mulches should be used alone only when there is no other mulching
material, when they are used in conjunction with temporary seeding during
periods when mulch is not required, or where waste-site covering operations
occur when seeding cannot be done (Clar et al., 1981).   At other times chemical
tacks and binders may be used on any exposed area which is being stabilized,
within permissible limits.   The chemical binders may be used in arid regions
and on droughty soils, but their effectiveness in lowering soil-moisture
evaporation rates is less than that for conventional organic mulches.  Chemical
binders are, however, excellent for short-term binding/tacking of conventional
organic mulches.   All chemical binder applications must be inspected, and
reapplied if necessary, periodically up to 60 to 90 days or until  the plantings
have become firmly established.  This is particularly necessary after rain-
storms that may have dislodged the chemical mulch (Clar et al., 1981).

    Chemical soil stabilizers are designed to coat and penetrate the soil
surface and bind the soil particles together.  They are used to protect bare
soil slopes, not subject to traffic, from wind and water erosion during tempo-
rary establishment of a seedbed.   Chemical stabilizers are used in lieu of and
in conjunction with temporary mulch material to provide mulch tack and soil
binder.  Chemical stabilizers can be applied only to a very finely prepared
seedbed.  Soil moisture, temperature, and texture influence the success of the
application.  Their limited applicability and high cost makes them undesirable
except where absolutely necessary.  It is recommended that chemical soil
stabilizers be tested on small, representative plots of ground before deciding
to use them extensively.  As a general rule, chemical stabilizers do not
provide protection for as long a period of time as straw, hay, and other
organic mulches.'


         4.9.4.7 Nonbiodegradable Mulches


    Mulches made of nonbiodegradable material, such as fiberglass and various
plastics, protect seedbeds during the critical germination and early plant
development period, and act as reinforcement following establishment of the
vegetative cover.  These materials include nettings and loose, stringy products
that can become securely enmeshed in the vegetation at the ground surface and
in the rootmat.  Also see "erosion-control fabrics" in the next paragraph.
Proper installation by experienced personnel is vital to the success of these
measures.  Light applications of crushed stone or gravel can also serve as a
long-term mulch.   Table 4-39 contains information on specific long-term
mulches.

                                     4-132

-------
Petroset® SB
                                                                 TABLE  4-37

                                               SUMMARY OF  CHEMICAL  RIMPERS MID TACKS
                                    (U.  S.  Environnental  Protection  Agency, October  1976)
Name
Aerospray®
52 Binder
Aerospray®
70 Binder
Aerospray®
72 Binder
Uses
Temporary
Soil
Stabilizer Mulch
X X
X X
X X

Mulch
Tack
Water di
emulsion
phytotox
X Water di
liquid p
emulsion
X Water di
alkyd em
D
spe
ic.
escription
rsible, alkyd
Nontoxic. Non-
pH 8-9
rsible,
spersible , liquid

Any
ment
Fydr
lire
be a
Hydr
lize
Applic
ation Meth
nonair entraining
(as for liquid fe
r).
oseeder. Seed, fe
pplied w
oseeder.
r, and w
i th produc
Seed, fe
ood fiber
od
equip-
rti-
rti-
t ,
rti-
may be
Manufacturer or
Product Information
American
Industri
Plasti
Wavne, N
American
Indu^tri
Plasti
Wayne, N
American
Industri
Cyanamid
al Chemica
cs Divisio
eu Jersey
Cyanarnid
al Chemica
cs Divisio
ew Jersey
Cyanamid
al Chemica
Company
Is and
07970
Company
Is and
07970
Company
Is and
                                                                          applied with product.              Poetics  Division
                                                                                                         Wayne,  New  Jersey  07970

Aquatain               X         X             Water dispersible.  Non-     Hydroseeder or anv nonair        The Larutan Corporation
                                              toxic,   Nonflamirable.        entraining equipment.   Seed      1424 South  Allec Avenue
                                                                          and  fertilizer may be            Anaheim,  California  92805
                                                                          applied with product.

Curasol® AE             XXX     Water dispersible, poly-     Hydroseeder or anv nonair        American  Hoech^t Corporation

                                              emulsion.  Nontoxic,                                        Bridgewater, New Jersey  08876
                                              Nonphytotoxic. pH 4-5

Curasol* AH             X                X     Water dispersible, high      Hydroseeder or anv nonair        American  Hoechst Corporation
                                              polymer ^rithetic resin.     entraining equipment.   Seed      1041 Route  202-206 North
                                              Nontoxic.  Nonphytotoxic.     and  fertilizer may be  applied    Bridpewater, New Jersey  08876
                                              pH 4-5.                     with product.

DCA-70                 X         XX     Water dispersible, poly-     Hydroseeder or any nonair        Union Carbide Corporation
                                              vinyl acetate emulsion.      entraining equipment.            ChemicaIs and Plastics
                                              Nontoxic. Nonphytotoxic.                                    270 Park  Avenue
                                              Nonflammable.  pH 4-6.                                      New York, New York  10017

Genequa 169             X



Liquid Asphalt
ified liquid acrylic
resin.
Asphalt cement that is
dispersed or suspended
solvents.
Water dispersible, liquid
resin polymer.

Water dispersible oil
emulsion. Nontoxic .
Nonflammable .
pH 6.0±0.5.

Water dispersible,
powdered vegetable gum.


lizer, and wood fiber mav be
applied with product.
Hand-spray nozzle or an off-
set distributor bar attached
truck.
Hydroseeder. Seed and ferti-
lizer mav be applied with
product .
Any spraying equipment




Hydroseeder or, for dry
application, standard hopper
spreaders (as for fertilizers
or lime).
The Delta Companv
Charleston, West Virginia

Asphalt Institute
Asphalt Institute Building
University of Maryland
College Park, Marvland 20740
The Dow Chemical Company
Midland, Michigan 48640

Phillips Petroleum Company
Chemical Department
Commercial Development
Division
Bartleaville, Oklahoma 74003
Grass Growers, Inc.
P. 0. Box 584
Plainfield, New Jersey 07061

Urea-Formaldehyde                X             Urea-formaldehyde resin      Nonair entraining  equipment      U,  F.  Chemical Company
  Foam                                        plus  a  foaming agent,        for resin and foam.  Hvdro-      37-20  58th Street
                                              mixed and foamed with        seeder for -seed  and ferti-       Woodside, New York  11377
                                              compressed air, then        lizer.
                                              applied to soil.  Wetting
                                              agent is then applied  to
                                              the foam.  Seed and ferti-
                                              lizer sprayed on top.

XB-2386                 X                      Water dispersible,  liquid    In-fected into slurry at the      3M  Company
                                              reactive polvmer.           nozzle of a hydroseeder.         Adhesive^, Coatings and
                                                                                                         Sealers Division, 3M Center
                                                                                                         Saint  Paul, Minnesota 55101
                                                                    4-133

-------
                                  TABLE 4-38

                APPLICATION RATES FOR SELECTED BINDERS AND  TACKS
                              (Clar et al.,  1981)
     Name
                                                    Rate
Aerospray
  52 Binder
Aerospray
  70 Binder
Aerospray
  72 Binder

Aquatain
Curasol AE
Curasol AH
DCA-70
Liquid Asphalt
M-145
Petroset SB
Terra Tack
1 - Steeply inclined, exposed slopes - 1 gal/
    100 ft2 _ concentrated
2 - Seedbed - 30-45 gal (concentrate) per acre in
    dilution ratios varying up to 10 parts water
    to 1 part chemical.
On steeply inclined, exposed slopes - 0.5 to 1.5
gal/yd2 of mixture.  Mixture can have ratios
ranging from 7 to 20 parts water.
Mixture - 5.5 parts water to 1  part aquatain.
Approximately 3 gallons aquatain, plus required
water, per 1000 square feet of surface area is
normally required for most soil surfaces.

Flat Areas - 30 gallons to 1000 gallons water for
moist soils, 2000 gal - dry soils.
3:1 - 2:1 Slopes - 40-55 gallons to 1000 gallons
water for moist soils, 2000 gal - dry soils.

1.5:1 Slopes - 55-65 gallons to 1000 gallons  water
for moist soils, 2000 gal - dry soils.

Swales and Ditches - 90-100 gallons to 1000 gal-
lons water for moist soils, 2000 gal - dry soils.

For Straw Mulch Tack - 30-45 gallons to 150 to 300
gallons water with mulch blower, 300-500 gallons
water with hydroseeder, per acre.
For Hay Mulch Tack - 20-30 gallons  to 150-300 gal-
lons water with mulch blower,  300-500 gallons
water with hydroseeder, per acre.

Soil Stabilizer - 1:1 ratio with 0.5 or more  gal-
lons per square yard.
Chemical Mulch - 1 part to 20  parts water, 0.5
gallons per square yard - perm, soils.
Tack - 1 part to 10-20 parts water, disperse  330-
950 gallons of solution per acre depending on
strength, each acre should have 30-45 gallons of
concentrate.
Mulch - Spray rate - 0.15 - 0.30 gallons per
square yard
Tack - Spray rate - 0.1 gallon per  square yard
Spray rate emulsified - 0.04 gallons per square
yard
On Steeply Inclined, Exposed Slopes - 1.5 to  2.0
gal/yd2 of mixture.  Mixture usually ranges from
5 to 10 parts water for every  part  chemical.

Highly Variable - depends on different soil tex-
tures, desired penetrations, and intended usages.
In general, the greater the dilution ratio, the
deeper the penetration and the weaker the binding
strength for a given soil condition.  Specific
applications and cot formulas  and nomographs  are
furnished by the manufacturer.

Stabilizer - wet - 50 Ibs in 2000 gallons water
with seed per acre.  Dry - 86   Ibs per acre with
seed
Mulch Tack - long fiber mulches - 1:20 mix ratio -
apply 1000 gal per acre.  Short fiber mulches -
1:40 mix ratio - apply 2000 qal per acre.

             4-134

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                                  TABLE 4-39

                GUIDE TO  LONG-TERM  NONBIODEGRADABLE MULCHES'
Mulch Materials   Application Rates
                                    Remarks
Crushed stone
(including
limestone)
Gravel


Slag




Fiberglass
 6 to 10" thick
Enkamat, Geofab
and related
synthetic
fabrics
Riprap
 6 to 10" thick


 4 to 6" thick
Blanket should
completely cover
the disturbed
area

Strands applied
at a rate of 850
to 1,100 Ib/acre
Use available
sheet widths and
controlled size
openings.  Place
a 3-in.  layer of
sand having wide
gradation of par-
ticle sizes on
top of fabric
prior to use of
riprap

Use when overland
flow rate of
water exceeds
10 ft/sec
Most durable (especially granite), use on
cover soils prone to slipping, frost
heaving, -and seepage

Limestone on acid areas will not last as
long as other materials
Use on gentle slopes and flat areas only,
seepage of water, and frost heaving

By-product of steel blast furnace, uses
similar to crushed stone and gravel

Do not use with certain filter fabric
(Filter-x, etc.)

Use without additional mulch
Use only on limited critical areas
because of cost

Applied as a mat or blanket or in long
strands

Blanket form should be stapled

Long strands applied by compressed air
spraying

Erosion from beneath may be a problem
with blanket

Fabrics must be placed in intimate con-
tact with underlying soil.   On fill
sites, compact the soil to 90% of the
standard Proctor density before placing
the fabric.
Riprap is placed on top of the underlying
layer of sand which covers the synthetic
fabric.   The exact sand layer thickness
has not been determined, but it must be
placed between the fabric and the riprap.
 From Nolan et al.,  1976 and 1978;  cited  in  Lee  et  a!.,  1984.
                                    4-135

-------
         4.9.4.8 Erosion-Control  Fabrics
    Erosion-control  fabrics consist of synthetic fabric matting that can be
used as a replacement for concrete, asphalt,  and rock riprap.   See also the
discussion of "geotextiles" in section 3.4.3.6.   Erosion-control  fabrics allow
the establishment and maintenance of vegetation where nonvegetative stabiliza-
tion alone would be aesthetically unpleasing.   Seed is sown into  the material
and grass grows through it and eventually covers it.   See Figure  4-38 and also
detail drawings in Appendix B, "Case Histories."  Soil and sediment particles
are held by the filaments of the mat.   Installation and maintenance of these
materials can be less expensive than the use  of conventional  materials.
                                  FIGURE 4-38

                         "ENKAMAT" INSTALLED ON SLOPES
                                                  1 = Subsoil
                                                  2 = Enkamat
                                                  3 = Sedimentation
                                                  4 = Grass Area
    Claims have been made that these mats are effective on slopes up to 1:1
over a wide range of soil conditions; have successfully withstood 14 in.  of
rain during the first month after installation; and have stabilized both
natural and artificially compacted soils.  Manufacturers say these materials
are thoroughly compatible with all grass varieties and other types of vege-
tation.  "Enkamat" is the trade name of one soil reinforcement material
(Figure 4-38).  In sandy soils, an underlay of filter fabric should be used.

    Current thinking holds that fabric mats are especially useful on limited
and highly critical areas because of high installation costs.  These areas
include steep slopes and areas of high wind velocities.  Disadvantages other
than expense include (U. S. Department of Agriculture, Forest Service, 1979):

    •    High labor costs for pinning and anchoring the fabrics

    •    Erosion from beneath

    •    General ineffectiveness on rocky areas and rough surfaces

                                     4-136

-------
    Polyester fabric mats (nonwoven) should be installed in accordance with
the manufacturer's specifications.  Staples or ground fasteners may consist of
plain iron wire (No. 8-11 gauge); broad wire U-staple; narrow wire V-staple;
T-staple; and narrow, triangular wood survey stakes.  Stake lengths may range
from 12 to 18 in.  depending on the expected load maxima.  Staples should be
placed down the mat centers at 3-ft intervals.  Prior to installation of the
fabric mats one must:

    •    Shape and grade the slope, or other area to be protected, as required

    •    Remove all rocks, clods, or debris larger than 2 in.  in diameter that
         will prevent contact between the net and the soil surface

    •    When open-weave nets are used, lime, fertilizer, and seed may be
         applied either before or after laying the net.   When nonwoven matting
         is used,  apply the soil amendments and seed before the matting is
         laid (Clar et a!., 1981).  Traffic patterns should be across the
         slope to minimize the initiation of rills.


         4.9.4.9 Vegetative Maintenance


    Proper management and maintenance of the vegetative cover at a waste site
are vital to maintaining its stability.  There are essentially two management
strategies that can be employed at a successfully covered waste site.   The
more costly management strategy is the conventional  maintenance practice
(Lutton, Regan, and Jones, 1979).

    Once the selected vegetation is established on the landfill, at least a
minimum amount of maintenance is necessary to keep less  desirable, native
species from taking over any weak areas in the cover.   In most areas judicious,
occasional mowing will keep down weed and brush species.  Mowing should not
be done indiscriminately, however.  The blades of mowing machines may cut into
local high spots,  leaving them devoid of vegetation  (Heim and Machalinski,
1980), and the tires of mowing tractors may cause ruts to form.   Traffic pat-
terns should be varied to avoid this.   Annual fertilization (and liming if
necessary) will generally allow desirable species to out-compete the lower-
quality weedy species.  Occasional use of selective  herbicides usually con-
trols noxious invaders, but care must be taken to avoid  injuring or weakening
the desirable species, lest more harm than benefit result in the long run.
In rare circumstances, large insect populations may  threaten the stand of
vegetation so that insecticide application becomes desirable.

    The other management strategy strives for a self-sustaining vegetative
cover consisting of grass-legume mixtures with periodic  lime,  phosphorus and
potassium fertilizer applications as necessary to maintain a minimum vegetative
cover to control  erosion.   Under this management strategy, natural plant suc-
cession will  proceed and invasion of the site by shrubs  and trees may occur.
Control  measures to limit the establishment and growth of deep-rooted shrubs
and trees should be implemented, if required.   Mowing twice a year or the use
of herbicides to kill undesirable shrub and tree species should be considered.

                                     4-137

-------
    Grazing is a possible alternative to mowing.   Tests can be performed on
the grasses to insure that they are free of toxic substances.   Grazing combines
the benefits of keeping the grasses short, returning nutrients to the"soil
through animal wastes, and putting the land to economic use.   Should tests
reveal contamination of the grass, of course, grazing should be immediately
terminated.

    A refertilization and reliming program may have to be established to
ensure that the site receives sufficient nutrients to sustain the established
vegetation, particularly for domestic grasses and legumes.   In general, the
fertilizer requirements of native species would be lower than that for domestic
grasses and forbs.

    The most common methods used to determine refertilization/reliming needs
are soil tests, tissue tests, and observing deficiency symptoms.   Soil tests
are an important method for identifying nutrient deficiencies, with the excep-
tion of nitrogen, which is best detected by onsite observations or tissue
tests.  When using soil analysis for lime and fertilizer requirements, rely on
qualified suggestions of State soil testing labs or commercial labs; and
follow recommended procedures for soil sampling (U.  S.  Department of Agricul-
ture, Forest Service, 1979).

    Weeds may have to be removed from a cover system for a variety of reasons.
They may present a fire hazard, especially along roads; they may be aestheti-
cally displeasing;  they may be noxious, or provide too much competition with
desired plants.  Both mechanical and chemical means can be employed.  In
general, chemical means should be used only in highly selective situations
such as for control of noxious weeds (U.  S. Department of Agriculture, Forest
Service, 1979).

    The use of insecticides may need to be considered.   Before making any
attempt to control  insects, you should know (1) the name of the insect you
want to control; (2) the dangers of using chemicals to control insects; and
(3) whether the harm caused by the insects is sufficient to warrant use of an
insecticide (U. S.  Department of Agriculture, Forest Service,  1979).


    4.9.5 Nonvegetative Measures


         4.9.5.1 Stone Stabilization


    Heavy applications of crushed stone, gravel, or slag can be used to stabi-
lize highly toxic surfaces, or excessively wet seepage areas on slopes.
Crushed stone or gravel mulches retain their effectiveness indefinitely if
properly applied and protected from compacting traffic.  Sediment reduction is
estimated at 70 to 90 percent, and nutrient runoff reduction at 50 to
70 percent.  Stones 0.5 in. or greater in diameter will protect against rain
splash and sheet flow and can withstand wind velocities up to 85 mph (U. S.
Department of Defense, no date).


                                     4-138

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    In certain areas of dry climate and abundant gravel, for example the
Sacramento Valley of California, it may be feasible to construct the entire
surface layer of gravel.  Such a surface would be highly erosion-resistant.
It would be highly pervious, but so long as the barrier and drainage layers of
the cover system (discussed previously) were properly designed and built, the
system should function effectively.  The site would be less aesthetically
pleasing than a vegetated site, but it would be relatively maintenance-free.
         4.9.5.2 Soil-Cement
    Soil-cement has been discussed in Chapter 3 under nonsoil materials usable
in cover systems, and its use is discussed in detail below in sections dealing
with barrier and foundation layers.  It may be mentioned here that the surface
layer could be constructed of soil-cement.  Soil-cement is a relatively imper-
vious, rigid material, and the same cautions stated elsewhere in this Handbook
as to the risk of cracking would apply.   A soil-cement surface layer would be
relatively maintenance-free except for repairing cracks.   These should be


                                  TABLE 4-40

           MAINTENANCE PRACTICES FOR SURFACE STABILIZATION MEASURES3
         Practice
          Maintenance Procedures
Conventional mulches
(biodegradable)
Chemical stabilizers/tacks
Nonbiodegradable mulches
and fabrics
Stone surfacing

Soil reinforcement
materials and erosion
control fabrics
Channel stabilization
Inspect periodically
Remulch bare spots during design life

Inspect periodically
Reapply to bare spots during design life

Inspect periodically
Reapply where necessary
Fiberglass and plastic mats should be
  checked for erosion underneath the
  blanket
Inspect periodically
Reapply where necessary
Inspect after each storm until  vegetation
  has been established and look for under-
  cutting of material
Periodic inspection after vegetation has
  been established

Periodic inspection and repair  according
  to SCS standards and specifications for
  each practice
 From Lee et al.,  1984
                                     4-139

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anticipated, however, and a regular inspection program should be followed.
Soil-cement will not support vegetation, and a soil-cement surface could be
aesthetically inferior to a vegetated surface.   Also, small cracks in a soil-
cement surface would tend to be rapidly colonized by clumpy vegetation, which
would have to be killed by herbicides before it extended its roots and dis-
rupted the cover layer.


    4.9.6 Maintenance of Stabilization Measures
    Proper maintenance of any stabilization practice is essential for its
continued effectiveness.   Table 4-40 lists maintenance practices for nonvege-
tative measures.   Judgment is required in applying various chemical stabilizers
and fabric mats because their high cost dictates that their use be limited to
small areas of critical and sensitive waste sites.
4.10 Surface Water Management


    4.10.1 General


    Surface-water management refers to all features concerned with the manage-
ment or control of runoff.   Runoff is affected by:

    •    Surface slope

    •    Length of slope

    •    Uniformity of slope

    •    Drainage pattern

    •    Type and density of vegetation

    •    Soil texture

    •    Erosion resistance of soil

    •    Engineered ditches, diversions, and structures

    Two obvious factors affecting the rate and amount of runoff are the sur-
face's slope and the length of uninterrupted slope.  As the slope angle in-
creases, so does the potential velocity of runoff.   The point where the soil
begins to erode is generally a function of the type of soil and the type and
density of vegetation.   Also, as the length of slope (per given width of
slope) is increased, the larger the area receiving precipitation becomes.
This larger area has the effect of increasing the amount of runoff to be
handled, as well as increasing the contact time between the runoff and the
cover's surface.

                                     4-140

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    Another factor having a direct impact upon runoff is the uniformity of the
slope.   Naturally occurring discontinuities in a site's surface such as gul-
lies, hollows, dips, and cracks generally will slow down the rate of runoff
and can cause runoff to collect and pond.  The latter effect is of concern as
it forms wet spots, which are prime sources of infiltrating water.   Generally
a good preconstruction practice is to grade the site to a uniform slope.

    Other factors that must be considered in the site's surface-water-
management plan are the site's drainage patterns (natural and engineered), the
type and density of vegetation at the site, and texture and erosion resistance
of the soil at the surface.  Each of these factors has an influence on the
balance between infiltration and runoff.

    The designer must first consider the extent to which natural topography
and surface conditions can be utilized.  As a rule, it is desirable to avoid
extreme grade modifications wherever possible.  Therefore, the designer should
make changes in the existing topography only with care; however, the designer
must recognize existing or potential problems.  These problems include severe
erosion of the surface soil due to too steep a slope, surface cracks which
allow runoff to enter the subsoil or aid in creating gullies and rills, and
conditions which would lead to the destabilization of collapsible soils (such
as loess) or soils susceptible to piping (dispersive soils).


    4.10.2 Surface Water Management Program (SWMP)


    Runoff as a component of the water balance was discussed in section 4.2.
The goal of the SWMP is to handle the runoff in a controlled fashion; that is,
to conduct it off the site in such a way that it does not erode the cover
system.

    Four good sources of information for SWMP design, from which much of the
material here was drawn, are:

    a.   Lee et al. (1984), "Restoration of Problem Soil Materials at Corps of
Engineers Construction Sites."

    b.   Lutton, Regan, and Jones (1979),  "Design and Construction of Covers
for Solid Waste Landfills."

    c.   JRB Associates, Inc.  (1982), "Handbook for Remedial Actions at Waste
Disposal Sites."

    d.   Chow (1959), "Open Channel Hydraulics."

In addition, the cover designer will fund abundant information on riprap chan-
nel linings in Anderson, Paintal, and Davenport (1970), and extensive research
data on erosion resistance of grass-lined channels in Ree and Palmer (1949).

    It should be clearly understood that the SWMP is critical and unique in
one respect.  Together with the vegetative layer, it is the only part of the

                                     4-141

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cover system that is directly affected  by  emergency  weather conditions (violent
storms).  As explained in section 4.2,  the  possible  infiltration rate into any
soil has a maximum value, and subsurface flows  higher than this  are impossible.
On the other hand, there is no precise  limit  to  the  amounts of water that the
SWMP may sometimes be called upon to handle.  For  this  reason the designer
should exercise the utmost diligence to insure  that  both  the capacity and the
durability of the SWMP are satisfactory to  meet  their expected demands.

    Elements of the SWMP will generally fall  into  the following  categories:

    •    Land grading

    •    Waterways

    •    Diversion structures

    •    Check dams

    •    Outlet structures

    Examples of SWMP elements may be found  in the  Case  Histories in Appendix B.


         4.10.2.1 Land Grading


    Land grading is the reshaping of a  site's existing  topography in order to
maximize nonerosive runoff and promote  the  establishment  of vegetation.   Gen-
erally, land grading involves cut-and-fill  operations to  establish the site's
preoperational or closure topography.   Reverse-slope benches (Figure 4-39) are
also utilized to help stabilize and protect slopes and  disturbed areas.

                                  FIGURE 4-39
                        SLOPE WITH REVERSE-SLOPE BENCH
                                 Ditch or Diversion to divert
                                          surface flow


                        ~S > v^  *>-»  ^
          Bench to drain to
          stable outlet
            (U. S. Department  of  Agriculture,  Soil  Conservation Service, 1975)

                                      4-142

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    This grading or  "contouring" is carried out in accordance  with  a plan
based on an engineering  survey and layout.   This plan is  based on topographic
surveys and soil  investigations which outline the parameters within which the
contouring operation must operate.   These investigations  should outline condi-
tions relating  to slope  stability,  drainage patterns,  the SWMP's effect on
adjacent property, and requirements for drainage and water removal.

    Maximum overland flow distances should be controlled  as shown in Fig-
ure 4-40.   Land-grading  design criteria and considerations are presented in
Table 4-41.   Table 4-42  outlines items that bear consideration when preparing
construction specifications for land-grading.   Serrated cut slopes should be
constructed in  accordance with Figure 4-41.
                                 FIGURE 4-40

                  MAXIMUM ALLOWABLE OVERLAND FLOW DISTANCE

                      D(max)  = 15(X)
                              X(15-Y)
          distance   overland flow distance
         The  maximum total horizontal overland-flow-plus-slope dis-
         tance  (B) should not exceed 15 times the  side  slope  (X) of
         the  cut or fill slope.  Maximum allowable overland flow*
         distance  (in feet) to the top of the slope with  no diversion
         of surface water is determined by use of  the  formula A = X(15-Y),

         where:

         A =  Maximum overland flow distance in feet to  slope  crest.
         B =  Maximum horizontal distance in feet (not  to  exceed
             15X).
         X =  Side  slope; horizontal distance in feet to 1 foot vertical
         Y =  Vertical interval; height of cut/fill slope  in feet mea-
             sured vertically from bottom elevation of  slope  to slope
             crest.
   *lf  maximum allowable  overland flow is  exceeded,  surface
    water should be  diverted from the slope face  and carried to
    a stable  outlet,  or conveyed downslope with a designed
    structure.
                                    (U. S.  Department of Agriculture,  1975)
                                    4-143

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                                  TABLE 4-41

                LAND GRADING DESIGN CRITERIA  AND CONSIDERATIONS
a.  Provisions (such as waterways,  diversions,  and outlet structures)  should
    be made to conduct surface runoff safely to storm drains,  protected  out-
    lets, or stable water courses to insure that surface runoff will  not
    damage slopes or other graded areas.

b.  Cut and fill slopes should not be steeper than 2:1.  Where the slope is to
    be mowed, the slope should not be steeper than 3:1 (4:1  is preferred be-
    cause of safety factors related to mowing steep slopes).

c.  Reverse-slope benches or diversions should  be provided whenever the verti-
    cal interval (height) of any 2:1 through 5:1 slope exceeds 15 ft
    (Figure 4-39).

d.  The following applies to reverse-slope benches (Figure 4-39).

    1.  Benches should be located so as to divide the slope face as equally
        as possible and should convey the water to a stable outlet.  Soils,
        seeps, rock outcrops, etc., should also be taken into consideration
        when designing benches.

    2.  Benches should be wide enough to accommodate the construction equip-
        ment in use and provide for ease of maintenance.

    3.  Benches should be designed with a reverse slope of  5:1 or flatter to
        the toe of  the upper slope and with a minimum of 1  ft in depth.
        Bench gradient to the outlet should be  between  1 and 2 percent.

    4.  The flow  length within a bench should not exceed 800 ft unless  accom-
        panied  by appropriate design and computations.

e.  Surface water should  be diverted from the face of  all cut and/or fill
    slopes  by the use  of  diversions, ditches, and swales or conveyed downslope
    by the  use  of a designed structure, except  where:

    1.   The  length  of  overland flow (in feet)  to  the  crest  of the  slope
         (Figure 4-40)  does  not exceed  the distance "A"  for  any combination  of
         side  slopes and  vertical  intervals.

    2.   The  face  of the  slope  is  stabilized  and the  face of all  graded  slopes
         is  protected  from surface  runoff  until  they  are stabilized.

    3.  The face of the  slope  is  not subjected  to any concentrated  flows  of
         surface water from  natural  drainageways,  graded swales,  downspouts,
         etc.

 f.   Serrated cut slopes  should be constructed  so as  to facilitate long-lasting
    vegetative  stabilization.   These serrations should be  made  in rippable
     rock with conventional  equipment as  the excavation is  made.   Each  step or
     serrate shall be  constructed on the  contour and  will  have steps  cut at
     nominal  2-ft intervals  with  nominal  3-ft horizontal shelves.   These steps
    will  vary depending  on  the slope ratio of  the cut slope.   The normal  slope
     line is 1.5H:1V.   These steps will weather and  act to hold moisture, lime
     and fertilizer, and  seed, and to produce a much  quicker and longer lived
    'vegetative cover and slope stabilization.   Overland flow is diverted from
     the top of all  serrated cut slopes and is  carried to a suitable outlet
     (Figure 4-41).

 g.  Slopes should not be created so close to property lines as to endanger
     adjoining properties without adequately protecting such properties against
     erosion, slippage, settlement, subsidence, or other related damages.
                                    4-144

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                                  TABLE 4-42

               GUIDANCE FOR GRADING CONSTRUCTION SPECIFICATIONS
 1.  All graded or disturbed areas including slopes should be protected during
     clearing and construction  in accordance with the approved sediment con-
     trol plan until they are permanently stabilized.

 2.  All sediment control practices and measures should be constructed,
     applied, and maintained in accordance with the approved sediment control
     plan.

 3.  Topsoil required for the establishment of vegetation should be stockpiled
     in amount necessary to complete finished grading of all exposed areas.

 4.  Areas to be filled should be cleared, grubbed, and stripped of topsoil to
     remove trees, vegetation, roots, or other objectionable material.

 5.  Areas where topsoil is to be placed should be scarified to a minimum depth
     of 3 in. prior to placement of topsoil.

 6.  All fills should be compacted as required to reduce erosion, slippage,
     settlement, subsidence, or other related problems.

 7.  All fill should be placed and compacted in layers.   Loose lift thickness
     should not exceed 8 in. in thickness (may vary with size of compactor).

 8.  Fill material should be free of brush,  rubbish,  rocks,  logs, stumps,
     building debris, and other objectionable material that would interfere
     with or prevent construction of satisfactory fills.

 9.  Frozen materials or soft,  mucky,  or highly compressible materials should
     not be incorporated into fills.

10.  Fill should not be placed on a frozen foundation.

11.  All benches should be kept free of sediment during  all  phases  of
     development.

12.  All graded areas should be permanently  stabilized immediately  following
     finished grading.

13.  Stockpiles,  borrow areas,  and spoil  areas  should be  shown on the plans.
                                     4-145

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                                  FIGURE 4-41

                     TYPICAL SECTION OF SERRATED CUT SLOPE
                                                              Diversion
                 Original grade
                                             Normal  slope line
                                             or  steeper
                      Ditch
         4.10.2.2 Waterways
    A waterway has been defined as "a permanent,  design stormwater conveyance
channel, shaped and lined with appropriate vegetation or structural material
to safely convey excess stormwater runoff" (Lee et al., 1984).   However, an
uncontrolled hazardous waste site's SWMP may call  for temporary waterways, in
order to stabilize the site, which may not be included in the final closure
plan.  The discussion below applies, as appropriate, to such temporary water-
ways, as well as to the more formally defined permanent ones.

    Note, also, that wherever two planar sloping surfaces meet in a dihedral
angle, a "swale" is formed, which will become a de-facto waterway under storm-
water conditions.

    The design of a waterway requires consideration of the following factors:

     •   Total stormwater capacity requirements

     •   Velocity of flow

     •   Channel cross section

     •   Land availability

     •   Channel lining

                                     4-146

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     •   Maintenance  requirements

     •   Vertical and horizontal channel alignment

     •   Compatibility with the  site's  SWMP and  surrounding environment

     •   Outlet conditions

     •   Cost
    The commonly accepted design capacity  for waterways has been the peak flow
 from a 10-year-frequency storm.  However,  some state and  local drainage crite-
 ria require a design based on  higher stormwater requirements than the  10-year-
 frequency storm.  Therefore, as appropriate, state and local agencies  should
 be consulted when determining  capacity requirements.  The rainfall intensity
 can be estimated from site-specific documentation, if available, or if need
 be, from rainfall-intensity maps which may be found in sources mentioned above
 in Chapter 2 under "climate."

    A number of limits are imposed upon the designer by flow-velocity consid-
 erations.  The designer is faced with moving a volume of  runoff off the site
 rapidly.   From tlris standpoint, a design which maximizes  the velocity of flow
 would seem to be called for.   However, three controlling  factors are the ero-
 sion threshold of the lining materials, feasibility of constructing the neces-
 sary channel slopes, and availability of land for the purpose.   If the veloc-
 ity of flow in a channel will  scour the lining, then an adjustment needs to be
 made in the channel's cross section, slope, or both.   Consideration may also
 be given to decreasing the volume in a given waterway by  increasing the total
 number of channels in the SWMP.  However, there may be limitations on how much
 of the site area is usable for waterways, or space limitations on channel
 cross sections and slopes.

    Channel  cross sections can be rectangular,  V-shaped,  parabolic,  trape-
 zoidal, or circular (as with channels formed from corrugated metal  pipe).
 Properties of typical  cross sections are shown in Table 4-43.   Where conditions
 call  for relatively small  flow volumes, vee-shaped,  circular,  and parabolic
 channels  with small  top widths have been used.   An example is  a roadside ditch.
Where velocities in these ditches are relatively low and water infiltrating
 into the  cover soil  from the ditch is not a problem,  a grass lining is satis-
 factory.   However,  where higher velocities are encountered (as  in steep
 slopes),  a more erosion-resistant lining such as concrete, soil cement, bitu-
minous material, or riprap is required.

    Wide,  shallow parabolic channels are used where the volume  of water is
 larger than  that for V-shaped channels but the velocities are  low.   Space

                                     4-147

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availability  is a  big  factor for this wide, shallow  type of channel.  Grass  is
a common lining material,  but riprap or riprap/grass combinations can be
useful where  some  dissipation of energy (velocity) is  desired.

    Trapezoidal and  rectangular channels are normally  utilized where large
volumes of water are to  be carried at a relatively high  velocity.  Usually
trapezoidal channels are preferred over rectangular  ones,  as it is usually
easier to maintain the stability of the cut (side stability).   Normally, only
the more erosion-resistant linings (concrete, asphalt,  riprap,  etc.) are used
in these channels.

    Specific  procedures  for the design of waterways  are  presented in Appen-
dix H.
                                   TABLE 4-43

                 TYPICAL CHANNEL CROSS-SECTIONAL  CHARACTERISTICS
                (Chow,  1959;  Courtesy McGraw-Hill  Book Co.,  Inc.)
Section
Ezfb
Rectangle
r^/r-fr

TroplIOid
^^T
Triangle
Circle
^7i
}^~i
fcF^dl
Round -cornered
rictanqle (/>/•)
Round-bottomed
triangle
Area
A
bv





'I/'
\k(6 — sin 0).
2P, •'
371' + Si/2
(r/2 - 2)r» + (b + 2r)y
(,-2,r + 6 + 2B
'
Top width
T






*v
(sin \iB)dn
or
2 \/yMo — y)
3.4

6 + 2r

2(z(v - r) + r \/l + :=!
Hydraulir depth
U




6 + 2Zy


' \ sin L..tf /


('/2--L'.r!^!,

?
   SatUfactory approximation for the interval 0 < * S 1, white i " 4|//r. When t > 1, u« the exact upression P - (r/2)[\/l + r' + I/* In d + V'l + j!)|.
                                      4-148

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         4.10.2.3  Diversion  Structures
    A diversion  is a  small  structure that is used to intercept sheet  flow from
and to critically disturbed areas and convey or guide this water to stable
outlet points.   It may  be  a temporary or a permanent fixture.  Berms  or  dikes,
ditches or swales, or combinations of these fall under the classification of
diversion structures.

    In selecting a diversion structure,  consideration should be given to the
following factors:

    •   The amount of  runoff to be handled

    •   The site's topography

    •   The diversion's finished slope

    •   Required service  life

    •   Ease of construction and removal  (if necessary)

    Figures 4-42, 4-43, and 4-44 show diversion swales or ditches, dikes or
berms, and ditch-berm combinations,  respectively.   Table 4-44 gives design
criteria, while construction-specification guidance is given in Table  4-45.
Table 4-46 gives some examples of maximum velocities for unlined and  vegeta-
tively lined swales.
                                   FIGURE 4-42

                       TYPICAL  DIVERSION DITCH OR SWALE
                 (U.S. ENVIRONMENTAL  PROTECTION AGENCY, 1976)

                                    2:1 or flatter
            D  =  depth
            b  =  bottom width
                                  Cross-section
                                                            Existing ground
                    Flow
  * n..»i
                                 1% or steeper, dependent on topography
Flow
   Outlet as required.
                                                               A   A
                                    Plan view
                                      4-149

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                         FIGURE 4-43

                 DIVERSION  DIKE OR  BERM
   (U.  S.  ENVIRONMENTAL  PROTECTION  AGENCY,  1976)
    Cut or fill slope
                                                          Flow
                                                     Stone stabilization.
                                                     if required
                                       2:1 slope or flatter
                             Existing ground
H - height of dike
h = minimum height of
    protective reinforcement   Cross-section
imum width of
tectlve reinforcement
A A
A A
Positive drainage. (
sufficient to drain.)

A A

A A
Srade
A A
•p m
Vf

v y
Y
Y V
Y
Y y
Y
Y y
Y .
\^
                                       it or fill slop*
                            4-150

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                      FIGURE 4-44

                 COMBINATION DIVERSION
(VIRGINIA SOIL AND WATER CONSERVATION COMMISSION, 1980)
10% Settlement
0.3' Freeboard
             Typical  Parabolic  Diversion
10% Settlement
0.3' Freeboard
                                            I/JJE=I  IE=-||iii==nTiT:-
    Design Flow  Depth
            1
            Typical  Trapezoidal  Diversion
10% Settlement
   3' Freeboard


             Typical  Vee-Shaped Diversion
                         4-151

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                                  TABLE 4-44

                   DESIGN CRITERIA FOR DIVERSION STRUCTURES
a.   Primary applications of a diversion structure include (Lee, et al., 1984):

    1.   Preventing surface runoff from higher-elevated undisturbed or stabi-
        lized areas from coming in contact with exposed soil surfaces (graded
        spoils, cleared areas, roadways, etc.) and causing erosion.

    2.   Shortening the length of graded slopes, thereby protecting lower por-
        tions of a hillside or roadway from highly erosive surface water flow.

    3.   Preventing sediment-laden runoff from an exposed slope from exiting
        the construction site without first passing through a sediment deten-
        tion structure.

b.   A dike (Figure 4-43) should be used only as a temporary structure where
    relatively small  amounts of runoff are expected.

c.   Diversion structures that will exist for more than 30 days should be sta-
    bilized with grass,  riprap, etc.

d.   Applicable locations for diversions include:

    1.   Upgradient of any disturbed area to reduce the volume of surface run-
        off which will attack the disturbed area.

    2.   Along steep or long slopes to control sheet flow and reduce the slope
        length and steepness factor.

    3.   Along the base or toe of denuded and/or disturbed slopes to collect
        sediment-laden runoff and convey it to a settling basin.

    4.   Around soil stockpiles.

    5.   Along the sides of access roads.

e.   All swales (Figure 4-42) should be designed along the criteria established
    for channels.

f.   All temporary diversions and diversion combinations (Figure 4-44) should
    be designed to withstand the peak discharge from a 2-year, 24-hour storm.

g.   Swale channel velocities should be such that they will not allow an unde-
    sirable amount of erosion to take place nor allow excessive sedimentation.
    See Table 4-46.
                                     4-152

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                                  TABLE 4-45

         CONSTRUCTION SPECIFICATION GUIDANCE FOR DIVERSION STRUCTURES
1.  All trees, brush, stumps, obstructions, and other objectionable material
    should be removed and disposed of so as not to interfere with proper func-
    tioning of the diversion structure.

2.  Whenever feasible, the dike should be built before any disturbance begins.

3.  All dikes should be machine compacted to prevent failure and should be at
    least 85 percent standard Proctor density.   In wooded areas where top-of-
    slope access is limited, diversion dikes can be constructed as the slope
    is being finished by moving soil upslope and dumping it at the crest.
    Compaction is sacrificed in this instance.

4.  All diversion dikes should have positive drainage to an outlet.

5.  Dike stabilization should begin within 15 days of construction or less as
    site conditions dictate.

6.  The swale should be excavated or shaped to line, grade, and cross section
    as required to meet the criteria specified herein and be free of bank
    projections or other irregularities  which will impede normal flow.

7.  Perimeter swales should have a minimum grade of 1 percent and the bottom
    should be flat.

8.  Fills should be compacted as needed  to prevent unequal  settlement that
    would cause damage in the completed  swale.

9.  All earth removed and not needed in  construction should be spread or dis-
    posed of so that it will not interfere with the functioning of the swale.

10.   Diverted runoff from a protected or stabilized upland area should outlet
     directly onto a stabilized area or  into a grade stabilization structure.

11.   Diverted runoff from a disturbed or exposed upland area should be conveyed
     to a sediment trapping device such  as a sediment trap or sediment basin
     or within an area protected by any  of these practices.

12.   Vegetative stabilization should be  accomplished using information from
     Tables H-2 and H-3 (Appendix H) and 4-46.

13.   Periodic inspection and required maintenance should be provided.
     Diversion structures should be inspected at least every two weeks and
     repairs made when necessary.
                                     4-153

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                                  TABLE 4-46

           EXAMPLES OF PERMISSIBLE VELOCITIES FOR STABLE DIVERSIONS
                              (Lee et al.,  1984)
a.  Swales not completely lined
    with vegetation
Sand and sandy loam
Silt loam
Sandy clay loam
Clay loam
Clay, fine gravel, and graded
  loam to gravel
Graded silt to cobbles
Shale, hardpan, and coarse gravels
                                           Maximum velocity, feet per second
Clean water
1.50
2.00
2.00
3.00
3.75
4.00
6.00
Water transport!
colloidal silt
2.5
3.0
3.5
4.0
5.0
5.5
6.0
ng


b.  Vegetatively lined swales


	Cover	

Vegetative3
  (1) Tufcote
      Midland
      Coastal bermudagrass

  (2) Reed canarygrass
      Kentucky 31 tall
        fescue
      Kentucky bluegrass

  (3) Red fescue
      Redtop

  (4) Annuals
      Small grain
      (rye, oats, barley,
      millet)
      Ryegrass
 Range of Channel
Gradient (Percent)


     0 to 5.0
   5.1 to 10.0
    Over 10.0

     0 to 5.0

   5.1 to 10.0
    Over 10.0

     0 to 5.0
     0 to 5.0
Permissible Velocity
 (Feet per Second)


         6
         5
         4
         4
         3
         2.5
         2.5
 To be used only below stabilized protected areas.

 ""Used only as temporary protection until permanent vegetation is
 established.
                                     4-154

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         4.10.2.4 Check Dams
    A check dam is a temporary structure of stone or logs that, when placed
across a natural or man-made channel, is used to stabilize the grade or control
erosion.  Some specific applications of check dams include:

         1.   Temporary and permanent ditches or swales which for some reason
cannot receive a nonerodible lining for the required length of time.

         2.   Temporary and permanent ditches or swales which require protec-
tion during the establishment of their vegetative linings.

         3.   Where a relatively rapid change in grade or elevation takes place
which would endanger the stability of the ditch or swale.

    Figures 4-45, 4-46, and 4-47 illustrate several different types of check
dams.   In designing a check dam the following factors should be considered:

         1.   Materials generally used in check dams include concrete, metal,
rock,  gabions, wood, and baled straw and hay.   For other than short-term use,
wood should be treated with perservatives.

         2.   The drainage area being serviced by the check dam should not
exceed 10 acres.

         3.   The maximum height of a check dam should be 2 ft.

         4.   Spacing should be such that the toe of the upstream dam is at the
same elevation as the crest of the downstream check dam (Figure 4-48).

         5.   Riprap may be necessary at the downstream side of the check dam
to prevent scouring of the ditch or swale and to prevent undercutting of the
dam.

         6.   Consideration should also be given to aesthetic qualities of the
materials.

         7.   Check dams will  usually require additional analysis of the channel
design above and below the check dam.

         8.   Check dams should be located in a reasonably straight section of
the channel.

    Construction details to be considered are:

         1.   If a check dam is to be constructed from wood salvaged from the
clearing operations, these logs should be 4 to 6 inches in diameter and of
sound  quality.
                                     4-155

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          2.   Logs should be driven a  minimum of  18  inches into  the channel  bed
(more  if  into a cohesionless soil).

          3.   Filter fabric can be incorporated into  the upstream  face of the
check  dam (Figures 4-45,  4-46, 4-47).

          4.   Stone check dams should  be constructed  of 2- to 3-in.-diam stones.

          5.   Check dams  should be inspected periodically, especially after  a
significant  rainfall.
                                    FIGURE 4-45

              LOG CHECK  DAM - TYPE 1  (RICHARDS AND MIDDLETON, 1978)
                     SECTIONA-A   V'\A A  I >
                                               v
                                                          Rock Riprap
             Note: Securely Staple
                  Filter to Logs.
                Streambed
                                    2'
                      Rock Riprap"

                      SECTION B-B
Win.
NOTE: Use Plastic Sheeting.
Filter Cloth, or intermingled
brush as a Filter. Anchor Filter
with Rock.
                                        4-156

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                           FIGURE  4-46

LOG  CHECK  DAM  - TYPE  3 (RICHARDS AND MIDDLETON, 1978)
        Riprap in Streambed
          Where Required
                                                 Layer of plastic sheet-
                                                 ing  or filter cloth on
                                                 upstream face of  dam
                                                 where feasible.
                          PLAN VIEW
                    .4" to 6"Min. Diameter
 Riprap
                                                          into  existing
                                                   ground a minimum of
                                                   2' if possible.
                    FRONT ELEVATION
W = Natural channel
width or minimum of 2'
                              4-157

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FIGURE
4-47

        FIGURE
                 4-158

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         4.10.2.5 Outlet Structures
    The final links in a SWMP are the outlet structures.   These outlet struc-
tures include pipes and/or chutes which provide an exit for a concentrated
flow of surface runoff without causing erosion.  In the case where this con-
centrated flow is conveyed to a relatively flat slope, then usually a simple
pipe or channel outlet with the required outlet protection may be all that is
required.  Outlet protection is defined as methods and materials which prevent
the flow from an outlet pipe, channel, or conduit from eroding the soil at the
outlet structure and in the next channel reach.  However, if a rapid change of
elevation or grade exists at an outlet, then a downdrain structure is required.
Design and construction criteria for outlet structures are presented in Appen-
dix H.
4.11 Frost Action
    An item of concern to the cover designer may be the potential for frost
damage in cold climates.   However, there is reason to believe that such damage
can be prevented by proper design.

    When a saturated soil freezes, the pore water undergoes a volumetric
expansion of 9 percent.   The soil mass as a whole will expand by a fraction of
9 percent, equal to the porosity.  For example, a saturated soil of 50 percent
porosity expands by 4.5 percent.   Such uniformly distributed expansion should
not have a significant disruptive effect, although repeated expansion and
contraction overxthe years may cause slow movement down slopes, as pointed out
by Lutton, Regan,  and Jones (1979).

    The distress that highways suffer during freezing weather arises from the
phenomenon of frost heaving.  This process involves the formation of sizable
ice lenses within the soil, not simply the freezing of many minute pores to
form a frozen soil mass.   Frost heaving has been studied at great length, and
there are many excellent published discussions of it.  See, for example,
Mitchell (1976), Oglesby (1975),  and publications of the Highway Research Board
cited in these two sources.

    In brief, frost heaving requires three indispensable factors, any of which
by its absence is sufficient to prevent the process.   These are (1) frost-
susceptible soils, (2) freezing temperature, and (3) a supply of water.

    Frost-susceptible soils are those possessing to an appreciable degree both
the properties of permeability and capillarity.  The ice lenses that cause
frost heaving grow as water migrates to them through unfrozen capillary chan-
nels but, having reached the lense,  then freezes.  Capillarity is required to
draw the water through the soil.   Permeability is required for it to be possi-
ble for appreciable quantities of water to flow.   Because they possess both of
these properties,  the most frost-susceptible soils tend to be silts.
                                     4-159

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    The third indispensable element is a supply of water.   In effect this
means a water table.   This may be normal or perched;  if perched,  it may be
large or small in extent; but the essential requirement is a source from which
the water flowing to the lense through the capillary system may be replenished.
Eve^ if conditions are favorable for the growth of ice lenses,  without a water
supply they cannot grow.   They are starved, like a fire without oxygen.

    It is the latter factor, a water table, that is unlikely to be present at
a properly designed waste-site cover.   If a sufficient pool of  subsurface
water is present close to frost-susceptible soils, frost heaving might develop.
It should be preventable, however, by design and maintenance of a proper
drainage system.   No special design for frost heaving is required, only an
awareness of its causes and the exercise of care to see that the three causa-
tive factors do not come together in a given cover system.
                                     4-160

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                                   CHAPTER 5

                                 CONSTRUCTION
    Construction bears a close relation to design.  The quality of the cover
system depends on both.  The best possible design will not deliver good re-
sults if it is not carried into effect by good construction.   The designer,
in turn, needs to be informed about construction practices and problems in
order to prepare a realistic and constructive design.

    Measures taken to insure that the actual construction meets the standards
called for in the design come under the heading of construction quality con-
trol, which is treated in the next chapter.   Construction organization, meth-
ods, and equipment are considered in this chapter.


5.1 Operational and Construction Guidance


    The cover system's designer (or design team) should outline a set of
operational and construction procedures to be followed in each of the three
phases of cover construction:

    •    Site preparation

    •    Cover construction

    •    Site closure

There is not any single "best" procedural outline which can be efficiently
prescribed to fit the variety of Superfund sites across the United States.
An effective operational plan for a site in  a humid region could prove need-
lessly restrictive for a cover constructed at an arid site.   Therefore, the
cover's construction and operational procedure, like the cover's design it-
self, must be based upon site-specific information in order to recognize all
of the pitfalls associated with a particular site as well as  to exploit any
advantages.
                                      5-1

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5.2 Phases of Cover Construction


    5.2.1 Site-Preparation Phase


    The site-preparation phase encompasses the span of time from the securing
of the site up to the construction of the cover's first layer.   Generally, the
operations included in this phase include:

    •    Establishment of site security

    •    Initial clearing and grubbing

    •    Establishment of controlled surface drainage to prevent runoff of
         contaminants

    •    Establishment of the support facilities

    •    Establishment of internal access roads and soil stockpiles

    •    Precontouring site

    Since this Handbook deals with cover systems for CERCLA (Superfund) sites,
it is assumed that a state or federally enforced site-security program will
already exist at the site at the time the cover-construction contractor begins
operations.  It is a normal procedure for the construction contractor to
assume responsibility for the security of the site shortly before or at the
time he initiates operations.  Normally, these security measures include sur-
rounding the site with a security fence paralleled by a road for patrolling
the fence.  This fence should bear signs which clearly indicate that it is
dangerous to enter the site and that there is limited access (no trespassing)
to the site.  Generally, a security program's aim is to prevent the inadver-
tent intrusion of the general public onto the site.

    After the site .has been secured, the site's clearing and grubbing opera-
tions are initiated.  Clearing and grubbing are generally continual opera-
tions.  Ideally, the clearing and grubbing operation should not proceed so far
in advance of the construction operations that large denuded areas are created
which will cause erosion or slope-stability problems.  The amount the clearing
program may precede construction will depend upon the severity of the site
conditions causing or contributing to the problems.  This initial clearing and
grubbing should be enough to enable the contractor to establish his support
facilities (offices, repair shop, decontamination facilities, etc.) and any
internal access roads needed to reach the construction area, borrow pits, and
areas for stockpiling soils (if needed) (Figure 5-1).

    "Precontouring" a site is defined in this Handbook as establishing a uni-
form grade across the site (or portion of the site) as part of the surface
water management plan (SWMP) or to provide a stable, suitable working surface
from which to begin construction  operations.  The slope(s) established in this
operation may or may not parallel the site's final contours.  These initial

                                      5-2

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                              FIGURE  5-1

SIMPLIFIED SITE LAYOUT  SHOWING TYPICAL  CONSTRUCTION  FEATURES
                   SECURITY POAD
                       ~*
                     HAUL ROADS
                     NEVER CROSS
                      FINISHED
                       COVER
                  COVER PROGRESSES
                IN AN UPHILL DIRECTION
                                                         SUPPORT
                                                         FACILITIES
                                                       (REPAIR SHOP,
                                                     DECONTAMINATION
                                                     FACILITIES, EQUIP-
                                                      MENT STORAGE,
                                                          ETC.)
                                                    SUPPORT FACILITIES
                                                    (OFFICES, PARKING,
                                                          ETC.)
                                                                         BORROW
                                                                          AREA
                                                                           OR
                                                                          SOIL
                                                                        STOCKPILE
                                                                          AREA
                                                                             PUBLIC
                                                                             ACCESS
                                                                             ROAD
                                  5-3

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 slopes are  usually established by cutting down any high spots at the site and
 filling and compacting soil in the low areas.  Also, precontouring the site
 may  involve removing an area or layer of soil that is potentially troublesome,
 such as a layer of sandy soil or peat at the ground surface.


     5.2.2 Cover-Construction Phase


         5.2.2.1 Planning and Scheduling


    The cover construction phase begins with the initiation of operations
 surrounding the actual construction of the cover layers.   The procedural
 outline for this phase basically includes:

    •    Ongoing clearing and grubbing operations

    •    Establishment of the site's surface water management plan

    •    Cover construction plan outlining:

    •    - Construction processes associated with the installation of each
           cover element

    •    - Overall  site plan showing the elevation of each of cover elements
           at any point on the site as well  as their sequence of installation.

    •    Dust control  measures

    •    Location of any soil  stockpiles

    •    Area(s) suitable for carrying on operations during inclement weather
         (rain and  freezing conditions)

    •    Types of equipment to be used for  each construction process

    •    Traffic flow  plan for the site

    Because  it is impractical  (often impossible)  to construct a  cover element
(layer) across an entire site (with the possible  exception of the foundation
layer)  before beginning the next,  the construction of each layer must be
sequenced so that the  leading edge of the lower layer is  ahead of the upper
layer (Figure 5-2).   Since the finished slope of  the final cover surface  is
designed to  maximize surface-water flow,  cover construction should proceed in
an uphill  fashion (Figure 5-3).   In this manner,  flow is  maximized away from
the construction area  rather than toward it.

    Traffic  patterns on the final  layer of  soil  should be across the  slope to
minimize the initiation of rills.

    Care should be  taken during construction to prevent accidental  mixing of

                                      5-4

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                                   FIGURE 5-2

                 SEQUENCING OF LAYERS DURING COVER CONSTRUCTION
                                                               ANGLE OF REPOSE
                                                               OF THE SOIL
                 HYDRAULIC BARRIER LAYER
                      FOUNDATION LAYER
                                   FIGURE 5-3

                            DIRECTION OF CONSTRUCTION
     final cover
     surface
flow maximized away
from working face
working face
proceeds uphill
interceptor dike


  «	 flow
material from one  layer  into  another layer.   This is most likely to occur as  a
result of heavy rainfall  during construction.   If heavy rain does occur, the
affected area near the working  face should be cleaned up before construction
proceeds.  The flat area  on top of a newly completed portion of a layer  (see
Figure 5-2) should be wide enough so that cleanup equipment can operate  effi-
ciently, and equipment used (see next section) should have low enough ground
pressures so as not to cause  rut formation.   The most serious consequences  of
mixing would probably result  from infiltration of clayey fines into a granular
permeable layer.   Clay should be compacted soon after placement to make  it
more erosion-resistant.   (A compacted clay surface should be scarified or
otherwide roughened before the  next lift is placed upon it.)  If heavy rain-
fall is anticipated, the  clayey working face may be covered with plastic
sheeting, or with  a geotextile  to reduce the erosive power of raindrops.

                                       5-5

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         5.2.2.2 Equipment


    A commonly overlooked factor which can have a great impact upon the suc-
cess of a cover system is the equipment used.   One problem may arise out of
failure to recognize the effect a piece of equipment may have upon cover ele-
ments already constructed.  For example, if a sheepsfoot compactor is used on
a relatively thin sand drainage blanket overlying a gravel drain and separated
by a geotextile, there is a good chance that the sheepsfoot roller will cause
a rupture in the geotextile.   With the separating effect of the geotextile
gone, the gravel drain will clog.  Another problem could originate from over-
looking the impact that a change in equipment type could have on the quality
of the cover.   An example would be a contractor's choice to use a rubber-tired
dozer instead of a crawler type to spread the protective sand layer over a
geomembrane.   Mobility and speed are gained in going to a wheeled-type dozer,
but there is a substantial increase in ground contact pressure.  If the sand
buffer over the geomembrane were not thick enough to distribute this extra
pressure safely, or the foundation beneath the membrane not strong enough, the
geomembrane could be punctured or torn.

    Table 5-1  presents a general overview of equipment capabilities as they
relate to cover construction activities.  This table should be used for general
guidance only, as a particular type of equipment may rate better or worse
depending upon what other types of equipment are also being used, as well as
what types of soils and climatic conditions exist at the site.   Basically,
equipment used for cover construction can be grouped as:

    •    Excavators

    •    Earthmovers

    •    Compactors

    •    Specialty equipment

    The primary function of an excavator is to break up and remove material
but not haul  it.  Figures 5-4, 5-5, and 5-6 provide examples.  Earthmovers,
on the other hand, can excavate (to a degree) and move the soil from one place
to another.   However, the efficiency of these earthmovers varies with distance
(Figures 5-7,  5-8, and 5-9).   Compactors do what the name implies.  Fig-
ures 5-10, 5-11, and 5-12 present examples and Table 5-2 provides guidance on
their use.  Equipment items that are unique from the standpoint of more effi-
ciently performing the duties of several pieces of equipment combined, or
that are designed to do primarily only one type of job, are designated as
specialty equipment.  Examples of specialty equipment are shown in Fig-
ures 5-13, 5-14, and 5-15.
                                      5-6

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                                                                       TABLE 5-1



                                           APPLICABILITY  OF EQUIPMENT TYPES TO VARIOUS OPERATIONAL FUNCTIONS
Equipment Type
Dozer
Operational
Function
Site Preparation
and Maintenance
Excavate Cover
Materials
Haul Cover
Materials:
1. 300 ft (91 m)
or less
2. 300-1000 ft
(91-305 m)
3. More than
1000 ft (305 m)
Spread Cover
Materials
Compact Cover
Materials
Shape Cover
Materials
Crawler
G

E



F

P

P

E

G-F

G-F

Rubber-
Tired
F

f



G

P

P

G

G-F

G-F

Scraper
Towed
F

Ea



Eb

F

P

E-G

NA

F-P

Self-
Propel led
F

Ea



G-Fb

G

E

E-G

NA

F-P

Backhoe
Tractor
F-PC

E



C

C

C

NA

NA

NA

Excavator
NA

E



C

C

C

NA

NA

NA

Motor
Grader
G-F

NA



NA

NA

NA

G

NA

E

Loader
Crawler
G

£



F

C

C

G

G-F

G

Rubber-
Tired
F

G



G

C

C

F

G-F

F

Compactor
NA

NA



NA

NA

NA

NA

E

NA

Landfill
Compactor
P

P



F-P

NA

NA

F-P

E

P

Power
Shovel
P

E



C

C

C

NA

NA

NA

Dragline
F-P

E



C

C

C

NA

NA

NA

E - Excellent; G = Good; F = Fair; P « Poor;  C = Only in combination with other equipment; NA « Not Applicable




aHighly dependent upon site conditions and equipment size




 Economics of operation a prominent factor




""Depends on size of operation

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FIGURE 5-4

 BACKHOES
                    BACKHOE TRACTOR

                    Primary Use:
                    Advantages:
                    Disadvantages:
    Excavation of small -
    width trenches.
    Small-capacity excava-
    tion and hauling unit.

    Versatile piece of
    small equipment. Useful
    in construction of
    drainage ditches and
    trenches for gravel
    drains.  Good mobility.

    Small size limits capa-
    city.  Hauling capabil-
    ities optimized when
    used in combination
    with trucks.
                BACKHOE  EXCAVATOR
V
                Primary  Use:


                Description-



                Advantages:
                Disadvantages:
Excavation below work-
ing level.

Capacities 0.5-4 cu.yd.;
ground pressure 6-15 psi;
speed 2-2.5 mph.

Greater capacity than
backhoe tractor.  Moves
materials when it excav-
ates them.  Can dig
harder materials than
dragline.  Greater reach,
more articulate than
power shovel.

Must use in combination
with trucks to optimize
effectiveness.  Slow
rate of travel.   Must be
loaded on trailer to
transnort. otn'rklv.
      5-8

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                                      FIGURE 5-5

                             POWER  SHOVEL  AND DRAGLINE
                                                                    POWER SHOVEL

                                                                    Primary Use:

                                                                      Excavation  above working
                                                                      level

                                                                    Capacities:
                                                                      Commonly 4-14 cu.yd.,
                                                                      larger capacities not un-
                                                                      common. Typical excavation
                                                                      rates for average condi-
                                                                      tions 70-90 cu.yd./hr. per
                                                                      cu.yd.  of bucket capacity.

                                                                    Advantages:

                                                                      Very versatile  for mixing
                                                                      layered materials during
                                                                      excavation; can excavate
                                                                      much harder materials than
                                                                      dragline; larger capacity
                                                                      than backhoe excavator.
   Disadvantages:   Fairly accurate  truck  spotting required when loading.  Excavates  hard
                    materials  in  large  chunks that must be broken prior to compaction.
                                                                   DRAGLINE

                                                                   Primary Use:

                                                                     Excavation  below working
                                                                     level

                                                                   Capacities:

                                                                     Usually comparable to power
                                                                     shovel, though some drag-
                                                                     lines use larger buckets.

                                                                   Advantages:

                                                                     Very  effective in excavat-
                                                                     ing  pervious materials from
                                                                     below water table'; effect-
                                                                     ive  where borrow-pit bottom
                                                                     is too  soft to support
                                                                     trucks  or scrapers.
Disadvantages:    Generally slower than shovels and scrapers; cannot excavate hard materials;
                 less efficient than power shovel  in mixing layered material in borrow pit.
                                            5-9

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                                     FIGURE 5-6

                              CONVEYOR-TYPE  EXCAVATOR
Primary Use'     High-volume excavation with direct discharge  into hauling unit

Description:     Capacity 4,000-16,000 tons/hour; vertical  cutting face 10-15 ft;
                conveyor length  up  to 60 ft.

Advantages:      High volume of excavation; good blending  of material; enables selective
                excavation of horizontally stratified soils;  can excavate horizontally
                or vertically.

Disadvantages:   Borrow areas must be relatively flat; slow travel speed; has difficulty
                with soils containing cobbles.
                                           5-10

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                                          FIGURE  5-7


                                             DOZERS


Primary Use:     Pushing earth or other materials  over  short distances

Description:     (Small and medium-sized tracked bulldozers) Weights 15,000-70,000 Ib; horsepower 65-
                 300 HP; ground contact pressures  8-13  psi  (standard models) or 4-7 psi (low-ground-
                 pressure models); speeds up to 7  mph.

Advantages:      Very versatile machine employed in numerous construction uses; e.g., clearing and
                 grubbing, helping to push-load scrapers  and front-end  loaders, ripping hard materials,
                 finishing slopes, excavating access roads, assisting other mobile equipment by push-
                 ing or pulling.  Blade may be angled horizontally and  vertically.

Disadvantages:   When working in close proximity to barrier cover layer (especially with geomembranes),
                 great caution required to avoid puncturing barrier with blade or tracks. Similar cau-
                 tions for other cover layers.  Dozer has limited capacity for compacting and hauling
                 material.
                                                          TRACKED DOZER

                                                             Available in numerous  sizes,  in  standard
                                                             and low-ground-pressure  models
                                                           WHEELED DOZER

                                                              Used where speed and maneuverability
                                                              are required.  Small and medium-sized
                                                              machines have speeds c' 18-30 mph,
                                                              turning radius 20-30 ft.  However,
                                                              ground contact pressures may be
                                                              20-25 psi.
                                               5-11

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                                    FIGURE  5-8
         SCRAPERS  (STANDARD,  ELEVATING,  AND  TOWED  TYPES)
Primary Uses:

General Descriptions:
Advantages:
Disadvantages:
                       Excavation, hauling, depositing of  soil materials

                       Capacities 10-25 cu.yd,; weights 27-68  tons; ground contact pressures
                       loaded,  45-65 psi; engine horsepower  150-350 HP.

                       Rapid-moving type of excavation machinery; larger, faster machines
                       can compete with trucks as hauling  units.  Scrapers can be used to
                       selectively excavate horizontally stratified soils and deposit
                       materials  in even layers, sometimes eliminating need for additional
                       spreading  equipment.  Breaking up of  material as it is excavated
                       facilitates later compaction.

                       May prove  unsatisfactory in very soft materials; tandem-powered,
                       push-pull  models required in such environments.  Adverse grades
                       may require tandem-powered models.  Scraper's efficiency as hauling
                       unit decreases with distance.
                                                    STANDARD TYPE

                                                    Self-propelled; available in single-engine
                                                    and  tandem-powered models (second  engine  for
                                                    rear tires).  When used alone, single-engine
                                                    model  is best suited to flat terrain and  fav-
                                                    orable excavation conditions.  In  adverse
                                                    conditions  single-engine scraoer is usually
                                                    pushed or pulled by crawler dozer  or another
                                                    scraper.  Tandem-powered scraper reduces  this
                                                    dependence  but sometimes operates  more effic-
                                                    iently in push-pull configuration  with another
                                                    scraper or  dozer.
•*'••.  « -       "Jlf ** *
                                                     ELEVATING TYPE

                                                     Does  not rely solely on cutting  edge  and
                                                     scooping action of bowl to load  self;  employs
                                                     loading elevator to aid in loading  and unload-
                                                     ing soil.  Available in single-engine and
                                                     tandem-powered models.  Generally has good
                                                     capability for working alone.   Soils  undergo
                                                     more  mixing  (blending) than with other scraper
                                                     types.
                                                       TOWED TYPE

                                                       Usually towed by a crawler  tractor, wheeled
                                                       tractor, or self-propelled  scraper where
                                                       excavation conditions require  good traction
                                                       and haul distance is relatively  short.
                                          5-12

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                                     FIGURE  5-9

                                 FRONT-END  LOADERS
Primary Use:    Excavate and  load cover materials; haul  small  quantities  short distances.
                                            TRACKED TYPE

                                            Description:

                                              Weight 15,700-55,000  lb.; ground contact
                                              pressures 5-12  psi; capacities 1-3.75 cu.yd.;
                                              horsepower 50-200  HP.

                                            Advantages:

                                              Low ground contact pressures available with
                                              tracked models.  Can  be used in combination with
                                              trucks to increase haul efficiency.

                                            Disadvantages:

                                              Does not spread  over  as well as dozer.  Slower
                                              moving than wheel-type loader.  Lower bucket
                                              capacity than wheel-type loader.
                                                  WHEEL  TYPE

                                                  Description:

                                                    Weight 21,000-60,000 lb.; ground contact
                                                    pressures 11-46 psi; capacities 1.25-5 cu.
                                                    yd.; horsepower 50-250 HP.

                                                  Advantages:

                                                    More mobile, greater bucket capacity than
                                                    tracked type.  Can be used in combination
                                                    with trucks to increase haul  efficiency.

                                                  Disadvantages:

                                                    Higher ground contact pressures
                                        5-13

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                                      FIGURE  5-10

                                SHEEPSFOOT  ROLLERS
Primary Use:       To compact fine-grained soils or coarse-grained  soils with appreciable
                  plastic fines

Descriptions:      Weights 2,000-4,000 Ib. per foot of drum length;  ballasted with water
                  or sand and water.

Advantages:        Kneading, churning, and tamping action  mixes  soil and water better than
                  other compaction equipment (this does not preclude proper processing of
                  material prior to compaction, however); produces  good bond between lifts;
                  breaks down weak rock or cemented soils.

Disadvantages:     Leaves surface rough and loose, and therefore susceptible to wetting by
                  rains or surface waters.  Compacts to shallower  depth than other equipment.
                  Effectiveness diminished in compacting  soils  containing cobbles or large
                  rock fragments.  Self-propelled rollers sometimes cause shearing or
                  laminations in fill.
                                                                   TOWED MODEL
                                                                   SELF-PROPELLED MODEL
                                             5-14

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                                    FIGURE  5-11

                      VIBRATORY  STEEL-WHEEL  DRUM  ROLLER
Primary Use:


Typical
Specifications:
Advantages:
Disadvantages:
To compact cohesionless materials  or materials where a smooth finished
surface is desired (such as asphalt or  soil-cement)


Vibration:  between 1,100 and 1,500 vpm;  dynamic force:  not  less than
40,000 Ib.  at  1,400 vpm;  weights  7,000-20,000 lb.;  compaction speed:
not to exceed  1.5 mph.


Greater densities can be obtained  in cohesionless soils  than with tamping
or rubber-tired equipment.  Fill may be flooded with water to improve
compaction.


May cause  degradation of soil  or rock-fill particles and create layers
of fines.
                                        5-15

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                                       FIGURE  5-12

                                RUBBER-TIRED ROLLERS
Primary Use:      To  compact cohesive and cohesionless  soils  where a smooth compacted surface
                 is  desired

Description:      Weights 18,000-25,000 1b.; wheel  spacing, distance between adjacent tires
                 not to exceed 1/2 of tire width.

Advantages:       Compacts to greater depths than sheepsfoot  roller.  Produces relatively
                 smooth compacted surface which is rain-resistant.  Effective in compacting
                 in  closer quarters than sheepsfoot.   More effective than sheepsfoot in
                 compacting cohesive soils containing  large  particles.  Wet areas of fill
                 can be determined by observation  of  roller  rutting.

Disadvantages:    Compacted surfaces must be scarified  before placing next lift.  Not as
                 effective as sheepsfoot roller in breaking  down soft rock or mixing fill
                 material.
                                                              LARGE-WHEEL, TOWED MODEL
                                                               SMALL-WHEEL,  SELF-PROPELLED
                                                               MODEL
Courtesy Bros Division  of American Hoist and Derrick Co.


                                            5-16

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  Equipment
     type
 Sheepsfoot
   rollers
Rubber tire
  rol1ers
Smooth wheel
  rollers
Vibrating
  baseplate
  compactors
Crawler
  tractor
      Applicability
 For  fine-grained soils or
 dirty coarse-grained soils
 with more than 20% passing
 No.  200 mesh; not suitable
 for  clean coarse-grained
 soils; particularly appro-
 priate for compaction of
 linings where bonding of
 lifts Is Important.
For clean, coarse-grained
soils with 4-8% passing
No. 200 mesh.

For fine-grained soils or
well graded, dirty coarse-
grained soils with more.
than 81 passing No. 200
mesh.
Appropriate for subgrade
or base course compaction
of well-graded sand-gravel
mixture.
Hay be used for fine-
grained soils other than
1n earth dams; not suit-
able for clean well-graded
sands or sltty uniform
sands.
For coarse-grained soils
with less than about 12%
passing No. 200 Mesh; best
suited for materials with
4-8* passing No. 200 mesh,
placed thoroughly wet.
Best suited for coarse-
grained soils with less
than 4-8% passing No.  200
mesh, placed thoroughly
wet.
                                                              TABLE  5-2

                                            COMPACTION  EQUIPMENT  GUIDANCE
                                           Requirements for compaction of 95 to 100 percent Standard Proctor
                                                                    maximum density
Compacted
11ft
thickness. Passes or
1n. (cm) coverages
6
(15)
Dimensions and weight of equipment
Foot Foot
contact contact
area,. pressures.
Soil type 1n. (cm4) ps1 (MPa)
   10
  (25)
                                               6-8
                                             (15-20)
  8-12
(20-30)
                                               6-8
                                             (15-20)
  8-10
(20-25)
 10-12
(25-30)
                                                        4-6 passes
                                                        for fine-
                                                        grained
                                                        soil; 6-8
                                                        passes for
                                                        coarse-
                                                        grained
                                                        soil
                                                        3-5
                                                        4-6
                         Fine-grained
                         soil   PI > 30

                         Fine-grained
                         soil   PI. < 30

                         Coarse-grained
                         soil
                  (32-77)     (17-34)
                    7-14
                  (45-90)

                   10-14
                  (64-90)
 200-400
(1.4-2.8)

 150-250
(1.0-1.7)
                                                         3-4
 Efficient compaction of wet soils  re-
 quires less contact pressures than the
 same soils at lower moisture contents.

 T1re Inflation pressures of 60 to  80
 ps1 (0.41-0.55 MPa) for clean granular
 material  or base course and subgrade
 compaction; wheel  load  18,000-25,000 Ib
 (80-110ktl); tire Inflation  pressures 1n
 excess of 65 ps1 (0.45  MPa) for fine-
 grained soils of high plasticity;  for
 uniform clean sands or  sllty fine
 sands, use large size tires with pres-
 sure of 40 to 50 ps1 (0.28-0.34 MPa).

 Tandem type rollers for base course or
 subgrade compaction, 10-15  ton weight
 (89-133 kN), 300-500 Ib per lineal  1n.
 (3.4-5.6 kN lineal  cm)  of width of real
 roller.

 3-wheel roller for  compaction of fine-
 grained soil; weights from  5-6 tons
 (40-53 kN) for materials  of low plas-
 ticity to 10 tons  (89 kN) for materials
of high plasticity.


 Single pads or plates should weigh no
 less than 200 Ib (0.89  kN);  may be used
 1n tandem where working space 1s avail-
able; for clean coarse-grained soil,
vibration frequency should  be no less
than 1,600 cycles per minute.
No smaller than  DB  tractor with blade,
34,500 Ib (153 kN)  weight, for high
compaction.
Possible variations  In  equipment

For large projects  (In  order  to
maximize width of pass),  drum of
60-1n.  dlam. (152 cm),  loaded to
1.5-3 tons per lineal ft  (43.7-
87.5 kN per lineal m) of  drum
generally 1s used; for  smaller
projects, 40-1n.  d1a. (101 cm)
drum, loaded to 0.75 to 1.75
tons per lineal  ft  (21.9-43.7 kfi
per 14neal m) of drum Is  used;
foot contact pressure should  be
regulated so as to avoid  sharing
the soil on the third or  fourth
pass.
            Wide variety of rubber tire com-
            paction equipment 1s available;
            for cohesive soils, Hqht-wheel
            loads such as provided by
            wohble-wheel equipment, nay be
            substituted for heavy-wheel load
            1f 11ft thickness 1s decreased;
            for coheslonless soils, larqe-
            slze tires are desirable to
            avoid shear and rutting.
            3-wheel  rollers obtainable  1n
            wide range of sizes; 2-wheel
            tandem rollers are available  1n
            the range of 1-20 tons (8.9-178
            kN) weight; 3-axle tandem rol-
            lers are generally used 1n  the
            range of 10 to 20 tons (89-17P
            kN) weight; very heavy rollers
            are used for proof rolling  of
            subgrade or base course.
            Vibrating pads or plates  are
            available, hand-propelled,  or
            self-propelled single  or  1n
            qanqs with width of coveraae
            from 1.5-15 ft (n.45-4.57 n);
            various types of v1brat1ng-drum
            equipment should be considered
            for compaction 1n large areas.

            Tractor weight up to 60,000 Ib.
Power
tamper or
rammer
For difficult access,
trench backfill; suitable
for all Inorganic soils.
4-6 1n
(10-15 cm)
for silt
or clay;
6 1n. (15 cm)
for coarse-
graded soils
30 Ib (0.13 kN) minimum weight; consid-
erable range 1s tolerable, depending on
materials and conditions.
Weights up to
foot diameter
3.93 cm).
250 Ib (1.11 kH);
4 to 10 1n. (1.57-
Source:   EPA/530/SH-870, "Lining of Waste Impoundment'and  Disposal Facilities"
                                                                   5-17

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                                        FIGURE 5-13

                                   LANDFILL COMPACTOR
Primary Use:     Spreading and compacting  cover materials

Description:     Weights 45,000-70,000 lb.;  horsepower 200-300 HP;  drum width 3-4 ft; number
                of drums: 4; drum diameter  4-5 ft.

Advantages:      Relatively high-speed compactor; dual-purpose machine  (spread and compact);
                undercarriage less vulnerable than dozer tracks;  variety  of wheel types
                available.

Disadvantages:   Not as good as dozer for  spreading or excavating  cover materials; wheels chop
                as well as compact, may tend to shear soil.
                                                                   LANDFILL COMPACTOR
                                                                    DETAIL OF WHEEL
                                             5-18

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                                       FIGURE 5-14

                                        TRENCHER
Primary Use:      Excavating narrow slit trench for anchoring geomembranes and placing utility
                 or drainage lines
                 Lightweight, compact, and maneuverable;  some tractor-mounted models have a
                 backhoe attachment.
Advantages:


Disadvantages:    A specialized piece of equipment with limited  field of usefulness
                                                      HAND-OPERATED MODEL

                                                      Description:

                                                        Weight  500-1,100 lb.; horsepower 5-10 HP;
                                                        trench  widths 3-12 in.; trench depths 24-
                                                        60 in.; ground'contact pressure 5-10 psi.
                                                       TRACTOR-MOUNTED MODEL

                                                       Description:

                                                         Weight 1,500-10,000  lb.;  horsepower 15-
                                                         100 HP; trench widths  3-24 in.; trench
                                                         depths 60-95 in.;  ground  contact press-
                                                         ure 10-40 psi.
                                            5-19

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Primary Use:

Description:

Advantages:
                                      FIGURE  5-15

                                    MOTOR GRADER
Shaping and  smoothing cover

Weight 25,000-55,000 lb.; horsepower 125-250 HP; speed 25-30 mph.

Can be used  to  dig  "V" notch anchor trenches for geomembranes.  Performs
road maintenance.   Accurate method of shaping  slopes and obtaining grades.
Available with  variety of blade widths.
Disadvantages:    Relatively restricted field  of applications.
                                           5-20

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    5.2.3 Site Closure Phase
    Site-closure activities are basically twofold in nature.

    •   The institutional care and maintenance required to stabilize the
         cover system are performed.

    •   The cover system is monitored to ascertain that it is performing its
         design function.

    Theoretically, the closure phase begins when the final stretch of cover
layer is installed.  However, since the cover's final elevation and grade are
not reached all at once, but rather in a progressive state of completion
(Figure 5-2), there is some overlap between the construction and closure
phases.  While a new section of the cover system is being constructed, closure
operations are underway to stabilize and monitor the portion of the cover
already completed.

    Institutional care and maintenance activities include repairing damage
from erosion, slope failures, subsidence or any occurrence, foreseen or unex-
pected, which is not directly related to a design flaw.  These problems by
nature do not require perpetual active mantenance.


5.3 General and Special Construction Operations


    Most of the construction operations carried on during the installation of
a cover system are standard ones common to earthwork in general.  A partial
list of construction operations and functions is presented in Table 5-3.   It
is outside the scope of this Handbook to describe common construction opera-
tions.  Excellent sources of information on construction are Nichols (1962)
and Church (1981).

    Briefly discussed below are certain special construction operations perti-
nent to installation of waste-site covers.


    5.3.1 Mixing and Placement of Soil-Cement


    When constructing a soil-cement layer, mixing may be done in place or in
a central plant.  Mixing in place involves spreading the portland cement over
the soil and dry-mixing or blending it into the soil evenly.  This is normally
accomplished by means of an agricultural disk harrow.  Water is introduced
into the soil-cement mixture, and mixing continues until the soil-cement is
uniform in color and free from wet and dry streaks.

    Central-plant mixing involves mixing the cement, soil, and water in a
batch plant similar to that used to produce concrete mixes.  The soil-cement
mixture is transferred to dump trucks, which take it to its final destination,

                                      5-21

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where it is placed in lifts of 6 to 8 in. thickness.  Generally, the central-
plant mixing operation creates a higher-quality soil-cement, as tighter quality
controls can be exercised.  However, acceptable results have been obtained
using the mixing-in-place method.
                                   TABLE 5-3
             PARTIAL LIST OF CONSTRUCTION OPERATIONS AND FUNCTIONS
Earthwork
     Borrow Pit
        Excavation
        Screening
        Mixing
        Watering
        Disking
        Loading
        Hauling
     Cover Site
        Dumping
        Placing
        Spreading
        Compacting
Installation
        Pipes
        Tiles
        Membranes
     Asphalt emplacement
     Concrete emplacement
     Soil stabilization operations
     Vegetation operations
Control  Operations
     Surveying
     Inspection
     Sampling
     Testing
Service Operations
     Transportation
     Fueling
     Lubrication
     Maintenance and Repair
     Field Sanitation
     Water Service
     Dust Suppression
     Trash Disposal
Management Functions
     Scheduling
     Supply management
     Personnel management
     Accounting
     Payrol1
     Record  keeping
     Field laboratory operation
     Security
     Safety
                                     5-22

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    After mixing and placing, the soil-cement is compacted by means of a
rubber-tired, sheepsfoot,  or steel-wheeled compactor.

    If a stair-step configuration (Figure 5-16) is used because of steep
slopes, the bond strength  between successive layers becomes important.   In
general, bond strength decreases with increasing delay between placement of
successive layers.   No more than one to three hours should elapse between
construction of successive layers.   Therefore, some operational planning is
required to meet this time limit.  Also, bond strength is enhanced if one or
more of the following procedures is used:

    •    Scarify the completed layer with a power broom or spiked-tooth tool,
         to a depth of about 1/4-inch, within one to three hours after con-
         struction of the  layer.

    •    Sprinkle dry cement (about one pound per square yard) on top of the
         moistened completed layer just prior to construction of the successive
         layer.

    •    Use a sheepsfoot  roller rather than a steel-wheeled or rubbered-tired
         compactor.  The dimpled texture left by the sheepsfoot may key the
         succeeding layer  to the lower layer.

    After the soil-cement  has been placed and compacted, the layer is immedi-
ately covered, to prevent  an excessive loss of water.   Some materials commonly
used for this purpose include waterproof paper, plastic sheeting, moist straw,
                                  FIGURE 5-16

                           STAIR-STEP CONFIGURATION
                     SOIL-
                     CEMENT
                                                 FOUNDATION
                                      5-23

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moist earth, and bituminous materials (RC-250,  MC-800,  RT-5,  and asphalt
emulsions).   The application rate for the bituminous materials varies from
0.15 to 0.30 gallon per square yard.


    5.3.2 Compaction of Foundation Layer


    Normally the compaction procedure proceeds  along the following outline:

    •    Preparation of the area to be compacted

    •    Adjustment of the water content

    •    Compaction of the material

    •    Scarification of compacted soil if another layer is  to be compacted
         over it and a bond is desired

    The initial preparation of the site usually involves the  clearing and
grubbing of any trees, stumps, brush, or other  vegetation that would have an
adverse effect on the cover system.  Spraying the ground with a soil sterilant
could also be necessary, as some hydraulic barrier materials  are susceptible
to plant penetration (such as thin asphalt and  synthetic membranes).  If this
clearing and grubbing leaves the surface in an  unsuitably loose condition or
if the existing surface is to be incorporated into the  foundation layer (as  is
usually the case), then the preparation phase will include scarifying the
surface (as necessary) with an agricultural type disk harrow  to facilitate its
compaction.   Even if compaction of the site's surface is not  specified, it is
a good practice to scarify it to assure a good  bond between it and the rest  of
the foundation layer.  If the site's  surface is not to  be compacted, then the
final phase of preparation would be to deposit  the material forming the first
layer (if more than one is required)  of the foundation  layer.   This is usually
accomplished by bottom-dumping out of scrapers  or end-dumping from trucks.

    After the material to be compacted is in place and  prepared, then its
water content is adjusted to that specified for the desired density.  The
water content of the soil is adjusted by disking the soil and air drying it,
if it is too wet, or spraying water (usually by trucks  equipped with tanks
and sprayers) and disking until the required moisture content is uniformly
achieved.   A good field indication that the soil is at  the proper moisture
content is how it reacts to the passage of the  compaction equipment.  If
excessive rutting or sinking of the compaction  equipment into the lift occurs,
this could mean that the water content is too high.   The absence of any
"spring" in the soil after the passage of the compactor could indicate that
the water content is too low.  Rapid moisture determinations  can be made in
the field with the nuclear moisture-density gauge (see  sec. 6.5 and Appen-
dix G).

    The deposition of loose lifts and their compaction  should be a highly
coordinated affair.  Ideally, these operations  should occur at the same time.
As one lane of soil is being compacted, an adjacent lane of material is being

                                      5-24

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deposited.   If another layer is to be compacted over a previously compacted
layer, then the lower layer should be scarified to ensure a good bond between
them.
    5.3.3 Placement of Asphalt Concrete
    Asphalt concrete is placed using conventional highway paving machines
modified (Figure 5-17) as necessary to work on the slope.   This modification
may entail  hooking a winch (at the top of the slope) onto the paving machine
for moving up the slope or attaching it (with chains or cables) to another
piece of equipment at the top of the slope for moving across the slope.   The
paver is supplied by dump truck, front-end loader, a moving conveyor, or a
combination of these.
                                  FIGURE 5-17

                            ASPHALT PAVING MACHINE

                                       1
    Compaction is accomplished using steel-wheeled rollers,  rubber-tired
rollers, and vibratory steel-wheeled rollers.
    5.3.4 Installation of Polymeric Barriers
    Construction of a polymeric barrier usually takes place as follows:

    •    Panels are spread by hand or machine (Figure 5-18) and anchored

    •    The panels are aligned and weighted down (Figure 5-19)

    •    Field seams are constructed (Figures 3-16 through 3-19,  Chapter 3)

                                      5-25

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         FIGURE 5-18



SPREADING POLYMERIC SHEETING
                     t^^iiliik*; kl^;Mi&
        a.   Manually
      b.  Mechanically
             5-26

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                                  FIGURE 5-19

                         SHEETING ALIGNED AND WEIGHTED
    •    Seams are inspected (Figure 5-20)

    •    Cover material is applied over the geomembrane (Figure 5-21)

    The figures cited above show membrane installation at liner rather than
cover sites because the number of sites where geomembranes have actually been
installed in waste-site covers is small.  However, see Figure B-5 in
Appendix B, "Case Histories," for an illustration of a membrane being placed
at a cover site.   The question of how steep a slope a geomembrane may be laid
on is discussed in section 4.6.3.4.

    Although possibly more economical than buying the machinery needed to
spread the polymeric material, laying the membrane out by hand has its
shortcomings.   The wind is usually the primary enemy as it can catch the
membrane and create a "membrane sail" which is difficult to hold down.  Also
it takes a highly coordinated effort to get a long line of men to correctly
align the sheeting.

    Although there are many seam testing devices available (infrared, ultra-
sonic,  air wand,  etc.) the one device that seems to have the confidence of the
designers is the vacuum-box tester.   However, it is a time-consuming method
that can only test a short length of seam at one time.   Also, the designer
must decide if this degree of assurance that his seam is completely watertight
is needed.

                                      5-27

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                 FIGURE 5-20



INSPECTION OF SEAMS (VACUUM-BOX SEAM TESTER)
                     5-28

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                             FIGURE 5-21



                   COVER APPLIED OVER GEOMEMBRANE
Note:   these views show liner rather than cover installations.



                               5-29

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    Polymerics are susceptible to some mechanical  failure mechanisms that are
not present in the other barrier materials.   They  are:

    •    Fold strain (Figure 5-22a)

    •    Tension from wind and anchorage (Figure 5-22b)

    •    Expansion-contraction forces (Figure 5-23)

    As the wind flows across the membrane it tends to lift it.   In large open
areas, the wind forces can be considerable.   If the end of the polymeric is
left unanchored, damage could result from the flapping of the membrane caused
by the wind.   This problem can be handled by:

    •    Anchoring the trench (Figure 5-24)

    •    Weighting down the edges with sandbags

    •    Using a wind cowl (Figure 5-25)

    Some polymeric materials, such as HOPE,  exhibit a high degree of expansion
and contraction when exposed to variations in temperature.  This creates addi-
tional stresses at the seam.  However, these stresses, by themselves, may not
be enough to break a field seam that is correctly constructed.   Therefore,
emphasis should be placed on the quality of the field seams in these types of
materials.  Also, these materials should be covered as quickly as possible to
reduce this phenomenon.

    Protection of the barrier during construction is very important.  In gen-
eral, all of the different types of hydraulic barriers require a protective
cover.  Usually this is a minimum of 6 in. of sand.  However, with the fre-
quency of machinery-generated punctures many manufacturers are raising this to
12 in.  The Asphalt Institute recommends a 12-in.  minimum protective cover
requirement.   This sand buffer may be replaced by a geotextile if it can be
shown that the geotextile will sufficiently protect the membrane from
puncture.
                                       5-30

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            FIGURE 5-22



   GEOMEMBRANE FIELD STRESSES
        a. FOLD STRAIN
                            ANCHOR TRENCH
         b. UPLIFT FROM WIND
            FIGURE 5-23



EXPANSION-CONTRACTION PHENOMENON
               5-31

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      FIGURE 5-24

  ANCHORING DETAILS
. poLVMEWC
                    PROTECTIVE COVER
     a. TRENCH CUT WITH BLADE OF
       MOTOR GRADER
      FIGURE 5-25

       WIND COWL
                             -CONCRETE
          5-32

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                                    CHAPTER  6

                          CONSTRUCTION  QUALITY  CONTROL
 6.1  Construction  Organization


     Three groups  contribute  to  the  quality  control  of  construction  of  covers
 for  uncontrolled  waste  sites:   (1)  design,  (2)  construction,  and  (3) inspection
 groups.

     The design group analyzes and designs,  and  produces  the plans and  specifi-
 cations which are the written standard of quality for  the cover(s)  to  be
 constructed.  This group also verifies the  design as the construction  group
 exposes site media.  All feedback from the  construction  and inspection groups
 is interpreted, and changes  to  the  design are made  when  necessary.

     The construction group provides all workmanship and  materials.  As site
 media are exposed, findings  are reported to the design group.  The  construction
 group is the element in the  quality-control system  that  physically  achieves
 the  standard of quality.

     Members of the inspection group sample, test, observe, and document during
 construction, and unacceptable workmanship  or materials  is reported to the
 construction group.  The inspection group provides  feedback to the  design
 group when possible.   In the quality-control system the  inspection  group
 assures that the  standard of quality has in fact been achieved by the con-
 struction group.

     This quality-control system works best  when all three groups interact and
 communicate for their mutual benefit.   It also works best when all  three
 groups report to  a single higher authority, so that none of the three groups
 holds a subordinate position to another.   When these conditions are met and
 the  three groups  work as a team, a synergistic effect results that  is benefi-
 cial to all.

     The higher authority referred to above, which might generally be called
 the  site manager, can complement this synergistic organization.  Intelligent
 scheduling,  to allow inspection-group functions to  be performed on a particular
 block of work while the construction group  is busy  on a different block of
work, is an example.   The site manager must also enforce the absolute nature
 of the standard of quality at a CERCLA site.  That  standard of quality must
 never be compromised.   This standard is the site manager's responsibility as
well  as that of all three groups.   The site manager must enforce the tenet

                                      6-1

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that cost-effectiveness is a consideration only if the standard of quality is
achieved.  Such direction by the site manager will greatly aid the three
groups by relieving them of the need to weigh quality versus
cost-effectiveness.
6.2 Quality-Assurance/Quality-Control of Construction


    Quality control of construction of covers for uncontrolled waste sites, as
considered here, pertains to the physical construction of the cover but not to
any site characterization nor to the design.   Quality assurance of construction
of covers for uncontrolled waste sites includes those actions by EPA, its
local agency (if there is one), and the site manager which assure that the
quality-control procedures for the construction will in fact assure that the
standard of quality is achieved.  In effect quality assurance is merely quality
control of the quality control.

    The quality-control procedures recommended for the construction of covers
for uncontrolled waste sites include tests and observations.   The difference
between a quality-control test and a quality-control observation is merely a
matter of the formality of the method involved.  As an example, consider the
quality-control procedures necessary to assure that a geomembrane seal has
been bonded properly.   An observation of 100 percent of the bonded seam would
reveal any large fishmouths, large anomalies, or incorrectly sealed portions.
The use of the air-lance method for 100 percent of the bonded seam would
reveal smaller fishmouths, anomalies, and incorrectly sealed portions unde-
tectable to the eye.   This air-lance method is considered a quality-control
test.
6.3 Quality-Control Observations


    Quality-control observations are made continually by the inspection group
while it observes the construction group work and while it actively performs
its inspection functions.   Quality-control observations of particular concern
for the construction of covers for uncontrolled waste sites are organized by
construction process and discussed below.


    6.3.1 Site Preparation


    The process of site preparation includes clearing, grubbing, stripping,
and grading.  The primary purposes for this activity are (a) preparation of
the uncontrolled waste site for excavation and/or embankment placement,
(b) construction of haul roads, and (c) altering the site drainage patterns.
The following observations should be made and documented:
                                      6-2

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         Observations of the exposed ground surface within the site limits,
         following stripping, as part of site media confirmation.  Normally,
         only visual-manual field identification procedures will be necessary
         (ASTM Designation D-2488).   If an unexpected material or zone con-
         figuration is encountered,  then more formal tests may be necessary.

         Observation of ground-surface contouring measurements to confirm
         adherence to the planned drainage pattern.

         Observation of the performance of the surface drainage system, during
         the first significant rainfall, to identify erosion or ponding
         problems.
    6.3.2 Excavation
    The preparation of an uncontrolled waste site may involve (a) excavation
below the ground surface and/or (b) the stripping and shaping of a natural or
man-made depression.   The following observations should be made and
documented:

    •    Detailed observations should be made of the exposed walls and floor
         for the purpose of site media confirmation.   These observations
         should be supplemented by confirmation tests for those features that
         conform to the site characterization studies.   Photographs are often
         of value.   The tests will usually consist of field consistency tests
         and those tests required for USCS classification, i.e.,  gradation
         and/or "Atterberg limits.   More extensive testing may be necessary if
         an unanticipated material or zone configuration is encountered.
         Undisturbed samples and engineering-properties tests may be justified,
         with additional samples tested for index properties.   Changes from
         expected site characteristics should not only be recorded, but imme-
         diately reported to the permittee's group responsible for the design
         function,  for possible revision of the design.

    •    Observations should be recorded of construction surveys  involving
         locations, slopes of walls,  and slopes of floors.   Conformance with
         planned slopes should be noted.

    •    During and after construction, visual  observations,  supplemented by
         surveying where necessary,  should be made and recorded of excavation-
         related soil movements.   These recordings should include heaving
         and/or cracking of the floor, and slaking,  sloughing, creep,  sliding,
         or  other movements of the side walls.   Again,  photographs may be of
         great documentary value.   Survey monuments,  placed at the start of
         construction,  should provide documentable data.

    •    Observations should be recorded of erosion  controls  for  conformance
         with plans.   These observations may include  perimeter ditches and/or
         dikes and  the placement of any spray-on erosion-inhibiting material,
         including  the material's  identification and  application  rate.

                                      6-3

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    6.3.3 Foundation Preparation


    If an earthfill embankment is used to partially or completely enclose a
waste site, the natural foundation and abutments must, as discussed in Engineer
Manual 1110-2-1911 (Dept.  of Army, 1977), (a) provide positive control of
underseepage, (b) provide satisfactory contact with overlying compacted fill,
and (c) minimize differential settlements and thereby prevent cracking in the
fill.   The observations made and recorded during foundation preparation should
include:

    •    The stripping to assure that all soft, organic, or otherwise undesir-
         able materials are removed.   Softness may be checked by a hand pene-
         trometer or similar device for a very relative strength estimate.
         Proof-rolling by construction equipment is often used to locate soft
         areas.

    •    The soil and rock surfaces for smoothness, adequate cleaning, and
         filling of rock joints and depressions.

    •     The construction of underseepage cutoffs, if used, to check required
         depth, materials encountered, backfill materials used, and proper
         placement of backfill.  If compacted fill is used, it should be
         observed as for other fills as discussed below.
    6.3.4 Compacted Earthfill


    Compacted earthfill barriers may be used to partially or completely en-
close a waste site.  When used they may include a compacted-soil hydraulic
barrier and a compacted granular hydraulic-conductor layer.   When finished
they may be overlain by a vegetation-supporting layer.

    The waste contained by the barrier system may consist of solid wastes with
moist soil backfill, which may eventually become saturated with water, or in
the case of a surface impoundment, it may consist of a high-water-content
slurry or sludge.  If appreciable steady-state seepage is expected, then in-
ternal seepage-control features such as filter drains and underseepage control
measures may be needed.  The system may contain a hydraulic barrier, such as
a geomembrane, supported by a compacted, low-permeability cohesive soil.  It
may also contain a hydraulic conductor, usually a granular filter material of
high permeability.

    The observations and tests that should be made (Dept. of the Army, 1977;
and USBR, 1974a and 1974b) and recorded during compacted fill placement, using
cohesive or granular soils are:

    •    The quality of the borrow materials must be tested.  The source of
         the borrow may be a natural borrow pit or a stockpile of soil from a
         trench excavation.  Two or more soils may be blended to produce a
         desired gradation or plasticity.  Samples of the borrow materials

                                      6-4

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should be tested for USCS classification (gradation and/or Atterberg
limits) and for natural water content.  If admixes are blended into
the natural soil, the application rate and uniformity of mixing
should be observed and documented.

Atmospheric conditions should be recorded.  Compaction specifications
often place restrictions on work performed just after a rainfall,
during very hot or windy weather, or during freezing conditions.

Equipment type, size, and compatibility with the soil type must be
evaluated and recorded.  For cohesive soil, a sheepsfoot roller,  a
tamping roller, or a rubber-tired roller may be used.  For clean,
granular soil, a vibratory roller is appropriate.  As given in Engi-
neer Manual 1110-2-1911 (Dept. of the Army, 1977), items to be checked
and recorded include:  (a) for a sheepsfoot roller, drum diameter and
length, empty weight and ballasted weight, arrangement of feet and
length and face area of feet, and yoking arrangement; (b) for a
rubber-tired roller, tire inflation pressure, spacing of tires, and
empty and ballasted wheel loads; and (c) for a vibratory roller,
static weight, imparted dynamic force, operating frequency of vibra-
tion, and drum diameter and length.

The uncompacted or loose lift thickness should be measured at several
locations in a layer of fill.  Both actual thickness and uniformity
of lift placement are of importance.  Loose lift thicknesses of (a) 6
to 8 in.  for a sheepsfoot roller, or (b) 9 to 12 in.  for a 50-ton
rubber-tired roller are usual for cohesive soils; while clean, granu-
lar soils should have loose lifts of (c) 6 to 15 in.  when using a
vibratory roller or 50-ton rubber-tired roller, or (d) 6 to 8 in.
when using a crawler tractor (Dept.  of the Army, 1977).   Measurements
are usually made with a marked staff or shovel  blade, although survey
levels should be made every few lifts for verification and documenta-
tion.   All level survey points should be referenced to the site grid
so that comparisons of lift thickness can be made directly.

Compactive effort and uniformity of compaction  should be observed and
recorded.   Compactive effort can be revised by  changing the number of
passes of the roller, the size and weight of the roller,  and/or lift
thickness.   For cohesive soils (a) six to eight passes of a sheepsfoot
roller or (b) four coverages of a 50-ton rubber-tired roller are
usual; while for a clean,  granular soil  (c) three or four passes  of a
vibratory roller or (d) three to six coverages  of a crawler tractor
are usual  (Dept.  of the Army, 1977).  Uniformity of coverage should
be closely observed,  particularly at fill  edges and in turnaround
areas.   When a crawler tractor is used,  the coverages must be by  the
tracks of the tractor.

Compacted density and water content should be measured and recorded.
The coordinate location of each test and the elevation of the ground
surface should also be measured.   The latter is a check on lift
thickness,  and when a retest of unacceptable fill is necessary,
serves to verify that no additional  fill  has been placed.

                             6-5

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    •    Laboratory compaction tests should be made of samples of the same
         fill soil whose field density and water content were measured in the
         item above.   The effectiveness of the compactive effort in the field
         is referenced to the laboratory compaction test.   Specifications for
         compaction of cohesive soil and "dirty" granular soil require
         achievement of a minimum percentage of the maximum density, at a
         water content within a specified range and related to the optimum
         water content, as determined by the specified laboratory compaction
         test procedure.   For clean granular soils, which densify more readily
         under vibration than under impact, a minimum relative density or a
         minimum percentage of the laboratory maximum dry density is usually
         specified.   This involves comparison of the density of the field-
         compacted soil with the maximum and minimum densities for the same
         soil developed in a specified laboratory procedure.


    6.3.5 Liner-Type Materials and Geotextiles


    The construction of a cover for an uncontrolled hazardous waste site may
include the construction processes involved in liner material or geotextile
installation.  The hydraulic-barrier layer of the cover system is expected to
provide a permeability smaller than a required value.   When this permeability
cannot be effectively achieved in a compacted soil  fill layer, then off-site
materials may be used.   The off-site materials may consist of bentonite,
Portland cement, asphalt, lime, or similar materials that are admixed through-
out or are mixed with only the surface lift of the compacted soil of the
barrier.   The barrier may also be a spray-on material  or a geomembrane.
Geotextiles may also be used as a filter aid or for soil reinforcement,  e.g.,
to enhance slope stability or cover strength.

    The tests and observations that should be made and recorded during liner-
material  or geotextile installation are generally material-dependent:

    •    For all off-site materials used (liner materials and geotextiles) the
         type and supplier's identification for the material  should be
         recorded.  Lot numbers or their equivalent are often useful in tracing
         materials of questionable quality to specific manufacturing
         procedures.

    •    For bentonitic and admixed-material layers these tests and observa-
         tions should be those whose results can be correlated with expected
         values of field permeability of any soil layer, i.e., field density
         tests and observations of layer thickness.  Where permeability is a
         significant consideration, laboratory permeability tests on field-
         compacted specimens ("plugs") are preferable to reliance on density/
         saturation correlations with laboratory-compacted specimens.  The
         hole resulting from the test must be filled and repaired.  (See tests
         and observations in the previous subsection on Compacted Earthfill.)
                                      6-6

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    •    The tests and observations for the installation of a port!and cement
         or asphalt liner are not within the framework of soils engineering.
         References describing these tests and observations include Dept.  of
         Army, 1971; Asphalt Institute, 1978 and 1979.

    •    For admixed materials, the spreading and mixing or blending equipment
         and procedures should be observed and recorded.   Reference should be
         made to industry standard methods, to manufacturer's recommended
         procedures, or other descriptions of the state of the art for the
         methods.

    •    For admixed materials, the application rate should be observed and
         recorded.   Methods for verifying the application rate, such as cali-
         bration of spreading devices,  should also be recorded.

    e    For admixed materials, compaction of the soil-admixture blend should
         be observed, tested, and recorded in the same manner as described
         earlier for Compacted Earthfill.   Soil classification tests,  observa-
         tions of lift thickness and of uniformity of rolling, observations of
         the suitability of blending and compacting equipment, and the compar-
         ison of field density (and water content, if applicable) with the
         specified laboratory control test, should all  be made and recorded.

    •    For spray-on materials, the observations and tests include identifi-
         cation of the material, verification of manufacturer's quality tests,
         application-equipment suitability, application-technique comparison
         with state-of-the-art directions, application rate,  application
         thickness, and uniformity of coverage.

    •    For geomembranes or geotextiles,  the supplier's materials identifica-
         tion marks should be compared  with the purchase-order or catalog
         descriptions.   The smoothness  of the placement surface, and its
         freedom from objects that might puncture the material, should be
         inspected.  If required, test  specimens may be cut from the field
         sheets; this will require patching, and the patching itself should
         also be observed and recorded.  The method of placement of the mate-
         rial should be recorded and supplemented by photographs if possible.
         The seams should be inspected  at numerous locations  and the required
         seam overlap measured and recorded.  The method of sealing the seam,
         whether thermal or adhesive, should be observed and  recorded; all
         seam formation should be closely inspected.   Seam-integrity tests, if
         specified, should be made and  recorded, including notation of the
         locations of the tests.   The entire placed material  should be system-
         atically inspected for imperfections or tears, and the results of the
         inspection recorded.


    6.3.6 Hydraulic Collector System


    The final cover may contain a permeable layer above the hydraulic  bar-
rier.   Its function is to change the direction of the percolating water from a

                                      6-7

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downward movement to a horizontal movement toward a nearby collector drain.
Usually it is formed of a clean granular material placed directly on the sur-
face of the impermeable hydraulic barrier.   The surface of the barrier is
sloped toward the collector system, usually located at the perimeter of the
disposal unit.  Observations and tests that should be made and recorded for
this feature are:

    •    The surface of the base for the permeable layer should be inspected
         and observations recorded.  Imperfections include soft soils, organic
         materials, the lack of specified admix or spray-on material, or leaks
         in a geomembrane.

    •    The amount and direction of slope of the permeable layer base should
         be verified and recorded.   This will usually involve standard survey-
         ing techniques.

    •    The clean granular materials used in the permeable layer should be
         tested for gradation, particularly for the presence of undesirable
         fines.   Comparison should be made to the specified gradation
         requirements.

    •    The placement, compaction, field density testing, and relative density
         testing should be performed and recorded as described above for
         Compacted Earthfill.


6.4 Quality-Control Sampling


    Quality-control samples must be drawn on a systematic basis in order to
justify confidence in test results.  This systematic basis for sampling, for
the purpose of testing, requires further discussion.   The statistical sampling
procedures described below are based in part on similar discussions in Hald
(1952) and American Society for Testing and Materials (annual).

    The method and frequency of sampling and testing in construction have tra-
ditionally been based on intuitive decisions of the sampler or his superiors.
The purpose of sampling and testing is to provide data for evaluation of a
portion of the work.   Unless sampled by probability,  or random,  sampling
methods, the result is often a biased and nonrepresentative estimate of a
quality characteristic.  Frequency of sampling and testing can only be ration-
ally discussed in statistical-analysis terms.  It is a function of desired
level of confidence,  maximum error or percent error,  and the actual variabil-
ity of the tested quality characteristic in the sampled portion of work.  Com-
parison of standard and alternative test methods can be made on the basis of
sample sizes needed for equivalence of confidence levels.


    6.4.1 Frequency of Sampling and Testing


    There is an inherent variability in measurement data for any specified

                                      6-8

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quality characteristic of any  soil mass, whether natural or construction-
processed.  Variability  in measurements occurs as a result of (a) material
composition variability, (b) placement (formation) process variability, and
(c) measurement process  variability.  All measurements contain variability
from all three causes combined.

    Each individual measurement of a quality characteristic may be considered
to be one of a "countably infinite" number of similar measurements that could
be made in a universe of the material.  The difference or error between the
measured value and the "true"  or reference value is the sum of components, an
accuracy (systematic or  calibration) error and a precision (random) error.
This can be written as (ASTM,  annual):


                                X = UR + 6 + e                           (6.1)


and


                                  6 = MR - Mp                            (6.2)


where

          X = numerical value of a measurement
         MR = true or accepted reference level of the property of the
              material to be measured
         Mp = the expected value or the average of many observations recorded
              for the process
          6 = correction for consistent or systematic error of the measurement
              process at the reference level   u
          £ = correction for random deviation about the average of the
              observations  |jp

    Accuracy refers to the degree of agreement of individual  measurements, or
the average of a large number of measurements, with a "true"  or accepted re-
ference value.   This definition implies the idea of a consistent deviation,
or systematic or bias error,  which is a fixed or common contribution to error
in each of a set of measurements.   Precision  is the degree of mutual  agreement
among individual  measurements of a consistent material  made under prescribed,
like conditions.   The imprecision of measurement may be characterized by the
standard deviation of the errors of measurement.

    In Equation 6.1,  the 6-term for correction for systematic,  or accuracy,
error is the sum of corrections from each of  the three  causes of nonrandom
variation and is  written:
                               6 = 6M + 6p + 6T                          (6.3)
                                      6-9

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where
6M =
 p ~
 T
              correction for systematic error due to material composition
              correction for systematic error due to placement process
              correction for systematic error due to testing process
    Because the effects of material composition, placement process, and testing
process are interrelated, it is not usually possibly to differentiate these in
a group of measurements.  If the material-composition and placement-process
effects are combined into a material quality effect, then:
and
where
                                 6Q = 6M + 6P
                                 6 = 6
                                                                (6.4)
                                                                (6.5)
         6n = correction for systematic error of the measurement process at
          ^   the reference level  UR  due to the material quality (the com-
              bined effects of material composition and placement process).

    The precision term of Equation 6.1,  e , is a random effect, and is the
combination of random effects due to the three causes discussed above.  The
statistical variance,  a§ , of a group of measurements of a characteristic of
a consistent material using a consistent test method is the sum of the vari-
ance due to the three causes of random variability.  This may be given as:
                      2    2
                     CT0 = CTM
                                             CT
and defining
 then
 where
a:  =
  o
  ~
                                  222
                                    = CT  + a
                                         ^
                                    = GQ + CTT
               overall  variance

               variance due  to material  composition

               variance due  to placement process

               variance due  to testing process

               variance due  to material  quality

                                       6-10
                                                                          (6.6)
                                                                 (6.7)
                                                                 (6.8)

-------
     If  the  variance  due  to  a  particular testing process,  a|  ,  is  known, or
 can  be  estimated, then its  effect on  the  overall variance,  a?  , can be eval-
 uated from  Equation  6.8  as:
                                                                          (6.9)
where
         aQ = total  standard deviation
         O-Q = quality standard deviation
         Oj = testing standard deviation

    When comparing alternative test methods, the effect of different standard
deviations of the test methods on the overall standard deviation should be
considered.  It can  be seen from Equation 6.9 that when material quality is
uniform (low a ) the precision of the test method (a ) is of great importance.
However, when material quality is not uniform (high a ) the relative precision
of one test method (a ) versus another is of little overall importance.


    6.4.2 Types of Sampling


    Probably the most satisfactory method to the engineer concerned about
sampling all parts of the block is a combination of (a) stratified random
sampling and (b) systematic sampling with a random start.

    If a universe, or block, consists of, or can be divided into, a group of
strata, then a random sample can be drawn from each stratum instead of drawing
a single random sample from the entire population.   This procedure is called
stratified random sampling.   The division of a soil  mass or a construction
process into blocks is a form of stratified random sampling.

    A popular sampling method is systematic sampling with a random start.
This method involves the selection of successive sample units at uniform
intervals of time, distance, area,  or volume.   It is argued that if the first
sample unit is selected at a random location,  then all  successive units are
random also.

    By subdividing each block of work into a convenient large number of sub-
blocks, using a random start,  and following a systematic pattern, a random
sample with uniform coverage of the block is obtained.


    6.4.3 Selection of Sample Size


    A statistically rational and valid method of selecting sample size is
given in ASTM (Annual) Designation E-122, "Standard Recommended Practice for

                                      6-11

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Choice of Sample Size to Estimate the Average Quality of a Lot or Process."
The equation for the number of units (sample size,  n) to include in a sample
in order to estimate, with a prescribed precision,  the average of some charac-
teristic of a lot is:
                                 n = (ta'/E)'
(6.10)
or, in terms of coefficient of variation
                                 n = (tV'/e)'
(6.11)
where
          n = number of units in the sample
          t = a probability factor, from the Student-t Tables
         a' = the known or estimated true value of the universe, or lot,
              standard deviation
          E = the maximum allowable error between the estimate to be made from
              the sample and the result of measuring (by the same methods) all
              the units in the lot
         V1 = coefficient of variation = a'/X , the known or estimated true
              value of the universe or lot
          e = E/X , the allowable sampling error expressed as a percent (or
              fraction) of  X1
          X = the expected (mean) value of the characteristic being measured
6.5 Quality-Control Tests


    Quality-control tests are performed on a scheduled basis by the inspection
group in accordance with the systematic sampling technique selected and pref-
erably in consonance with the construction group's work.  Quality-control
tests applicable to the construction of covers for uncontrolled waste sites
are listed in Table 6-1.  Tests are organized by geotechnical parameter.  For
most parameters, several test methods are given.  The selection of a partic-
ular test method should be made on a site-specific basis, as each method has
relative merits and limitations.  However generally performed, and thus gen-
erally recommended, test methods are indicated by the footnote to Table 6.1.
Descriptions of test methods are given in Appendix G.


6.6 Geomembrane/Geotextile Independent-Laboratory Verification Tests
    Certain tests are performed by geomembrane/geotextile manufacturers to
arrive at the specifications for their products.  These same tests are some-
times also performed by the design group, should they not accept the manufac-
turer's claims for his product.  The design group uses the test results to

                                      6-12

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                                                                               TABLE 6-1
                                                             QUALITY-CONTROL  TEST METHODS (SEE APPENDIX G)
                                   Method
                                                                         Number
                                                                                                                      Method
                                                                                                                                                           Number
Oi
 I
Parameter Measured:  Water Content
     Standard Oven-Dry3                                              1
     Standard Nuclear Moisture/Density Gagea                         2
     Gas Burner                                                      3
     Alcohol Burning                                                 4
     Calcium Carbide (Speedy)                                        5
     Microwave Oven                                                  6
     Infrared Oven                                                   7
Parameter Measured:  Unit Weight
     Standard Laboratory Volumetric                                  8
     Standard Laboratory Displacement                                9
     Standard Field Sand-Cone                                       10
     Standard Field Rubber Balloon                                  11
     Standard Field Drive-Cylinder                                  12
     Standard Nuclear Moisture/Density Gage                          13
Parameter Measured:  Specific Gravity
     Standard Laboratory                                            14
Parameter Measured:  Grain-Size Distribution
     Standard Sieve Analysis (+200 Fraction)                        15
     Amount of Soil Finer than No. 200 Screen  (Wash)  Standard        16
     Standard Laboratory Hydrometer ((-200 Fraction)                 17
     Pipette Method for Silt and Clay Fraction                       18
     Decantation Method for Silt and Clay Fraction                   19
Parameter Measured:  Liquid Limit
     Standard Multipoint3                                           20
     Standard One Point                                             21
Parameter Measured:  Plastic Limit
     Standard Laboratory3                                           22
Parameter Measured:  Consistency  (Cohesive  Soil)
     Standard Unconfined Compression3                                23
     Field Expedient Unconfined Compression                          24
     Hand Penetrometer3                                              25
     Handheld Torvane                                                26
Parameter Measured:  Water Content/Density/Compactive  Effort
     25 Blow Standard Proctor Compaction8                            27
     25 Blow Modified Proctor Compaction3                            28
     Nonstandardized Proctor Compaction3                             29
     Rapid, One Point Proctor Compaction                             30
     Rapid, Two Point Proctor Compaction3                            31
     Hilf's Rapid                                                    32
     Ohio Highway Department Nest of Curves                          33
     Harvard Miniature Compaction                                    34
Parameter Measured:  Relative Density (Cohesionless Soil)
     Standard Laboratory Maximum Density3                            35
     Standard Laboratory Minimum Density3                            36
     Modified Providence                                             37
Parameter Measured:  Geomembrane/Geotextile Seam Integrity
     Bonded Seam Strength3                                           33
     Breaking Strength3                                              39
     Peel  Adhesion3                                                  40
     Air Lance                                                       41
     Vacuum Box3                                                     42
     Conductivity                                                    43
     Ultrasonic                                                       44
        Generally recommended  or preferred  method.

-------
decide on the geomembrane/geotextile to be specified in the design.   The con-
struction or inspection group, like the design group, performs these same
tests.  The construction or inspection group must perform these tests to
assure that the product that arrives on site will in fact perform to the stan-
dard specified by the design.   Normally neither the design group nor the con-
struction/inspection group actually performs these tests itself.  They con-
tract an independent laboratory which has the requisite equipment to perform
the tests.   Thus although these tests can be considered quality-control tests,
they are not performed by the inspection group.   Thus they are not included in
the previous section on test methods.  However they will be merely identified
here:  ASTM designations D412 (tensile strength and elongation at failure)
D2240 (hardness), D413 (seam strength), D624 using die C (tear strength), and
Federal  Test Method Standard 101B (puncture resistance).


6.7 Quality-Assurance Program


    An effective quality-assurance program for the construction of covers for
uncontrolled waste sites may take many forms.   However any such program must
have as  its backbone complete documentation.  Everything of importance to the
quality-control system must be properly documented.   This includes every ob-
servation,  test, corrective action when a block of work is unacceptable, etc.
The operative aspect of a quality-assurance program for the construction of
covers for  uncontrolled waste sites must be and is complete, proper
documentation.

    In the  development of the Plan for remedial  action at an uncontrolled
hazardous-waste site, a Quality-Assurance program tailored to the particulars
of the site and the planned action(s) should be formulated.
                                      6-14

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                                   APPENDIX  A

                           REFERENCES  AND  BIBLIOGRAPHY
 ABC  Dirt/Soil  Scientists.   1981.   Soil  Properties,  Classification,  and  Hydrau-
      lic  Conductivity  Testing.   EPA/MERL  Contract No.  68-03-2933,  Seattle,  WA,
      128  pp.

 Abdun-Nur,  E.  A.   1964.   Discussion  of  "Significance  of  Test  Results  Obtained
      from Random  Samples,"  by J.  F.  Shook,  pp  13-30 i_n American  Society for
      Testing and  Materials  (1964), q.v.

 American  Association of State Highway and Transportation Officials  (published
      every  four years).   Standard  Specifications for  Transportation Materials
      and  Methods  of Sampling and  Testing, AASHTO, Washington, DC,  Two volumes:
      Part 1, Specifications; Part  2, Methods of Sampling and  Testing.

 American  Society  of Civil Engineers.  1949.  Hydrology Handbook.   Manual of
      Practice  No.  28,  ASCE, New York.

 American  Society  of Civil Engineers.  1969.  Design and  Construction  of Sani-
      tary and  Storm Sewers.  Manuals and  Reports on Engineering  Practice,
      No.  37, ASCE, New York.

 American  Society  for Testing and Materials  (Annual).   Annual  Book  of  ASTM
      Standards, ASTM,  Philadelphia,  PA, Multiple volumes, including the
      following:

      Part 15 - Road and Paving Materials; Bituminous  and Polymeric Materials
               for Highway  Construction,  Waterproofing and Roofing, and Pipe;
               Traveled Surface Characteristics

      Part 19 - Natural Building Stones:    Soil and Rock

      Part 35 - Plastics - General Test Methods, Nomenclature

      Part 37 - Rubber, Natural  and Synthetic - General Test Methods;  Carbon
               Black

      Part 38 - Rubber  Products,  Industrial - Specifications and  Related Test
               Methods; Gaskets; Tires

American  Society for Testing and Materials.   1959.   Symposium on Application
      of Soil Testing in Highway Design and Construction.   Special Technical
      Publication 239, ASTM, Philadelphia, PA, 127 pp.

American  Society for Testing and Materials.   1964.   Statistical  Methods for
     Quality Control  of Road and Paving Materials.   Special  Technical Publica-
     tion 362,  ASTM,  Philadelphia, PA, 51 pp.


                                      A-l

-------
American Society for Testing and Materials.   ]967.   Permeability and Capillar-
     ity of Soils.   Special Technical Publication 417, ASTM, Philadelphia, PA,
     210 pp.

American Society for Testing and Materials.   1970.   Special Procedures for
     Testing Soil and Rock for Engineering Purposes.  Special Technical Publi-
     cation 479, ASTM, Philadelphia, PA, 630 pp.

Anderson, A.  G., Paintal, A. S., and Davenport, J.  T.  1970.  Tentative Design
     Procedure for Riprap-Lined Channels.  NCHRP, Report 108, Highway Research
     Board, Washington, DC, 75 pp.

Anonymous.   1978.  Climates of the States.  Gale Research Co., Detroit, MI.

Antrim, J.  D., et al.  1970.  Rapid Test Methods for Field Control of Highway
     Construction.   NCHRP Report 103, Highway Research Board, Washington, DC.

Arkin, H.,  and Colton, R. R.  1950.  An Outline of Statistical Methods.  4th
     edition,  Barnes and Noble Inc., New York.

Asphalt Institute.   1976.  Asphalt  in Hydraulics (Revised edition).  Manual
     Series No.   12 (MS-12), The Asphalt  Institute, College Park, MD, 68 pp.

Asphalt Institute.   1978.  Asphalt  Paving Manual.  3rd edition.  Manual Series
     No. 8 (MS-8), The Asphalt Institute, College Park, MD.

Asphalt Institute.   1978.  Soils Manual.  Manual Series No. 10 (MS-10), March
     1978 edition, The Asphalt Institute, College Park, MD, 238 pp.

Asphalt Institute.   1979.  A Basic  Asphalt Emulsion Manual.  Manual Series No.
     19 (MS-19), The Asphalt Institute,  College Park, MD.

Atterberg, A.    1911.  Uber die physikal ische Bodenuntersuchung und Liber die
     Plastizitat der Tone  (On the  Investigation of the Physical Properties of
     Soils and  on the Plasticity of Clays).  Internat. Mitteil. f. Bodenkunde,
     v. 1 , pp 10-43.

August, H., Tatzky, R.,  Pastuska,  G., and Win, T.   1984.   Investigation of
     Permeability Behavior of Commercially Available  Polymeric Membranes  for
     Landfill Bottom Sealing in Contact  with Leachate, Organic Solvents,  and
     Their Aqueous Solutions.  Research  Report No.  103-02-208, Federal Envi-
     ronmental  Agency, Berlin, West Germany, 108 pp.

Auvinet, G., and Espinosa, J.  1981.  Impermeabilization of a  300-Hecture
     Cooling Pond, pp  151-167 j_n Zimmie  and Riggs (1981),  q.v.

Backstrom, J. E., Porter,  L. C., Ore, E.  L., and Wallace,  G.  B.   1974.
     Concrete in Construction.  Appendix F, pp  645-665, j_n  U.  S.  Bureau of
     Reclamation (1974a),  q.v.

Bailey,  R. G.   1978.   Description  of the Ecoregions  of  the  United States,
     U.  S. Department  of Agriculture, Forest  Service, Ogden,  UT.

                                      A-2

-------
Baker, D. E.  1976.  Soil Chemical Constraints  in Tailoring  Plants  to  Fit
     Problem Soils, j_n Wright  (1976), q.v.

Barenberg,  E. J.   1974.  Utilization of Ash  in  Stabilized Base Construction,
     pp  180-196 jm Faber, Echard, and Spencer (1974), q.v.

Bartos,  M.  J.   1977.  Use of Dredged Material in Solid Waste Management.
     Technical  Report D-77-11, U. S. Army Engineer Waterways Experiment
     Station, Vicksburg, MS.

Bell, J. R., Hicks, R. G., et  al.  1980.  Evaluation of Test Methods and Use
     Criteria for Geotechnical Fabrics in Highway Applications, FHWA/RD-80/
     021, Federal Highway Administration, Washington, DC, 191 pp.

Benjamin, J. R., and Cornell,  C. A.  1970.   Probability, Statistics, and Deci-
     sion for Civil Engineers, McGraw-Hill Book Co., Inc., New York.

Bennett, F. W., and Donahue, R.  L.  1975.  Methods of Quickly Vegetating Soils
     of  Low Productivity, EPA-440/9-75-006,  U.  S. Environmental Protection
     Agency, Washington, DC.

Bertrand, A. R.   1965.  Rate of  Water Intake in the Field, pp 197-209 j_n
     Black  (1965), q.v.

Black, C. A. (editor-in-chief).  1965.   Methods of Soil Analysis.   Monograph 9
     in  the Series, "Agronomy,"  in two volumes:   Part 1, Physical and Minera-
     logical Properties, Including Statistics of Measurement and Sampling;
     Part 2, Chemical and Microbiological Properties, American Society of
     Agronomy,  Inc., Madison,  WI, 1572 pp.

Blaney,  H.  F.   1952.  Definitions, Methods,  and Research Data.   Trans. Amer.
     Soc. Civil  Engineers, v.  117, pp 949-973.

Blystone, J. R., Pelaner, A.,  and Steffens,  G.  P.  1961.  Moisture  Content
     Determination by the Calcium Carbide Gas Pressure Method,  HRB  Bull. 309,
     pp  77-84, Highway Research  Board,  Washington, DC.

Bohannon, J. R.   1978.  Quality  Assurance Engineering for Nuclear and Other
     Complex Facilities, Report  No.  TID-28368, Dept.  of Nuclear Engineering,
     N.  Carolina State University, Raleigh,  NC.

Bouwer, H.  1978.   Groundwater Hydrology.   McGraw-Hill  Book Company, Inc., New
     York, 480 pp.

Bradshaw, A. D., and Chadwick, M. J.   1980.   The Restoration of Land:  The
     Ecology and Reclamation of  Derelict and Degraded Land.   University of
     California Press, Berkeley  and Los Angeles.

Bradshaw, A. D., Humphries,  R.  N., Johnson, M. S., and Roberts, R.   D.  1977.
     The Restoration of Vegetation on Derelict  Land Produced by Industrial
     Activity, in Holdgate and Woodman (1977), q.v.
                                      A-3

-------
Bradshaw, A. D., Marrs, R. H., Roberts, R. D., and Skeffington,  R. A.   1982.
     The Creation of Nitrogen Cycles in Derelict Land, Phil. Trans.  Roy.  Soc.
     London, B 296: 557-561.

Brady, N. C.  1974.  The Nature and Properties of Soils.  8th edition,
     Macmillan Co., New York, 639 pp.

Capp, J. P., and Spencer, J. D.  1970.  Fly Ash Utilization, Applications, and
     Technology, Info. Circ. 8483, U. S. Bureau of Mines, Washington, DC,
     72 pp.

Casagrande, A.  1932.   The Structure of Clay and Its Importance  in Foundation
     Engineering.   Jour. Boston Soc. Civil Engineers, v. 19, no. 4,  pp  168-221.
     Reprinted 1940 i_n "Contributions to Soil Mechanics," Boston Society  of
     Civil Engineers.

Casagrande, A.  1948.   Classification and Identification of Soils.   Trans.
     Araer. Soc. Civil  Engineers, v. 113, pp 901-991.

Cedergren, H. R.  1977.  Seepage, Drainage, and Flow Nets.   2nd edition,  John
     Wiley and Sons, Inc., New York, 534 pp.

Chow, V. T.  1964.   Handbook of Applied Hydrology.   McGraw-Hill Book Co.,
     Inc., New York.

Chow, V. T.  1959.   Open Channel Hydraulics.   McGraw-Hill Book Co.,  Inc.,
     New York.

Church, H. K.  1981.  Excavation Handbook.  McGraw-Hill Book Co., Inc.,
     New York.

Clar, M. L., Das,  P.,  Ferrandino, J., and Barfield, B.   1981.  Handbook of
     Erosion and Sediment Control Measures for Coal Mines.   Prepared by Hittman
     Associates, Inc., Columbia, MD, for Office of Surface Mining Reclamation
     and Enforcement,  U. S.  Department of the Interior.

Clayton, C. R. I.,  Simons, N. E., and Matthews, M.  C.  1982.  Site
     Investigation.  Halsted Press (Wiley), New York, 424 pp.

Clements, F.  E.  1920.  Plant Indicators - The Relation of Plant Communities
     to Process and Practice.  Publication 290, Carnegie Institution of
     Washington, Washington, DC.

Cline,  J. F.   1979.  Biobarriers Used in Shallow -  Burial Ground Stabilization.
     PNL-2918, Battelle Pacific Northwest Laboratory, Richland, WA,  15 pp.

Collins, R. J., and Miller,  R. H.   1976.  Availability of Mining Wastes and
     Their Potential for Use as Highway Material.   Vol  I, Classification  and
     Technical and Environmental Analysis, FHWA-RD-76-106,  Federal Highway
     Administration, Washington, DC, 294 pp.
                                      A-4

-------
 Collins,  R.  J.   1976a.   Availability of Mining Wastes and Their Potential for
      Use  as  Highway Material.   Vol  II,  Location of Mining and Metallurgical
      Wastes  and Mining  Industry Trends, FHWA-RD-76-107,  Federal Highway Admin-
      istration, Washington,  DC, 129 pp.

 Collins,  R.  J.   1976b.   Availability of Mining Wastes and Their Potential for
      Use  as  Highway Material.   Vol  III, Annotated Bibliography, FHWA-RD-76-108,
      Federal  Highway Administration, Washington,  DC,  38  pp.

 Collins,  R.  J., and Miller,  R.  H.   1977.   Availability of Mining Wastes and
      Their Potential  for Use as Highway Material  - Executive Summary.
      FHWA-RD-78-28,  Federal  Highway Administration, Washington, DC,  40 pp.

 Conway, R. A.,  and  Malloy, B.  C.  (editors).   1981.  Hazardous Solid  Waste
      Testing:   First Conference.  ASTM  Special  Technical  Publication 760,
      American Society for Testing and Materials,  Philadelphia,  PA, 386 pp.

 Creager,  W.  P.,  Justin,  J. D.,  and  Hinds,  J.   1946.   Engineering for Dams.
      Vol  III,  John  Wiley and Sons,  Inc.,  New  York.

 Critchfield,  H.  J.   1974.  General  Climatology.   3rd  edition, Prentice-Hall,
      Inc., Englewood Cliffs,  NJ.  446 pp.

 Daniels,  F.,  and Alberty, R.  A.   1961.   Physical  Chemistry.   John Wiley and
      Sons, Inc., New York, 744  pp.

 D'Appolonia,  D.  J.   1980.  Soil-Bentonite  Slurry  Trench  Cutoffs.  Jour.
      Geotech.  Eng.  Div. ,  ASCE,  vol.  106,  no.  GT4,  pp  399-417.

 Davidson, D.   T., et  al.   1960.   Methods for Testing Engineering Soils.   Bull.
      No.  192,  Engineering Experiment Station,  Iowa State  University,  Ames,  IA.

 Davidson, G.   R. , etal.   1974.   Bird/Aircraft Hazards.   SW-116,  U. S.  Environ-
      mental Protection Agency,  Washington, DC.

 Davis, F.  J.    1953.   Quality  Control  of Earth Embankments.   Proc. Third Intl.
      Conf. Soil  Mechs. and Found. Engineering,  Switzerland,  Vol  I, p  218.

 Davis, S.  N., and DeWiest, R. J. M.   1966.  Hydrogeology.  John  Wiley  and Sons,
      Inc., New  York,  463 pp.

 Dawson, J. F.   1950.  Control of Damage by Muskrats to Earth  Structures.
     Thesis.   University of Saskatchewan.

 Deming, W. E.   1950.  Some Theory of  Sampling.  John  Wiley and  Sons,  Inc.,
     New York.

 Department of the Army.   1970.  Stability of  Earth and Rock  Fill  Dams.   Engi-
     neer Manual EM 1110-2-1902, Washington,  DC.

Department of the Army.   1971.  Bituminous Pavements---Standard  Practice.
     TM 5-822-8, Washington,  DC.

                                      A-5

-------
Department of the Army.  1972.  Soil Sampling.  Engineer Manual EM  1110-2-1907.
     Washington, DC.

Department of the Army.  1977.  Construction Control for Earth and  Rock-fill
     Dams.  Engineer Manual EM 1110-2-1911, Washington, DC.

Department of the Army.  1978.  Contracts - Quality Management.  Appendix A,
     "Quality Control and Management," ER 1180-1-6, w/ch 1., Washington, DC.

Department of the Army.  1978.  Design and Construction of Levees.  Engineer
     Manual EM 1110-2-1913, Washington, DC.

Department of the Army.  1979.  Geophysical Exploration.  Engineer  Manual EM
     1110-1-1802, Washington, DC.

Department of the Army.  1980.  Laboratory Soils Testing.   Engineer Manual  EM
     1110-2-1906, Revised edition incorporating change 1,  May 1980,
     Washington, DC.

Department of the Army.  1984.  Geotechnical Investigations.   Engineer Manual
     EM 1110-1-1804, Washington,  DC.

Department of the Navy.  1971.  Soil Mechanics, Foundations,  and Earth
     Structures.   NAVFAC DM-7, Alexandria, VA.

Department of the Navy.  1982.  Soil Mechanics.  NAVFAC DM-7.1, Washington, DC.

Departments of the Army and Air Force.   1979.   Drainage and Erosion Control:
     Subsurface Drainage Facilities for Airfield Pavements.  TM 5-820-2, AFM
     88-5, Chap.  2,  Washington, DC.

Departments of the Army and Air Force.   1982.   Procedures  for Foundation
     Design of Buildings and Other Structures (Except Hydraulic Structures).
     TM 5-818-1, AFM 88-3,  Chap.  7,  Washington, DC.

Departments of the Army, Air Force,  and Navy.   1982.  Soil Stabilization for
     Pavements.   TM 5-822-4, AFM 88-7, Chap. 4, NAVFAC DM 21.5, Washington, DC.

DiGioia, A. M., Jr., and Nuzzo, W. L.   1972.  Fly Ash as Structural Fill.
     Jour. Power Div. ,  ASCE, vol.  98,  no.  PO 1, pp 77-92.

Dobrin, M. B.   1976.  Introduction to Geophysical Prospecting.  McGraw-Hill
     Book Co.  Inc.,  New York.

Dodge.   1980.   See McMahon, 1979.

Enrick, N. L.   1972.  Quality Control  and Reliability.   6th edition, Industrial
      Press, Inc., New York.

Epstein, E.  1976.  Genetic Potentials for Solving Problems of Soil Mineral
     Stress:  Adaptation of Crops to Salinity, j_n Wright (1976), q.v.


                                      A-6

-------
Evans, R. B.  1982.  Currently Available Geophysical Methods  for Use  in  Hazard-
     ous Waste Site Investigations, pp 93-115 j[n  Long and Schweitzer  (1982),
     q.v.

Faber, J. H., Eckard, W. E., and Spencer, J. D. (compilers).   1974.   Ash
     Utilization - Proceedings, Third International Ash  Utilization Symposium,
     Pittsburgh, PA, March  1973, Info. Circ. 8640, U. S. Bureau of Mines,
     Washington, DC, 317 pp.

Farmer, W. J., Yang, M., Letey, J., and Spencer,  W. F.   1976.  Problems  Asso-
     ciated with the Land Disposal of an Organic  Industrial Hazardous Waste
     Containing HCB, pp 177-185 j_n Fuller (1976), q.v.

Farmer, W. J., Yang, M. S., Letey, J., and Spencer, W. F.   1980.  Land Disposal
     of Hexachlorobenzene Wastes.  EPA-600/2-80-119, Municipal Environmental
     Research Laboratory, U. S. Environmental Protection Agency, Cincinnati,
     OH, 69 pp.

Federal Aviation Agency.  1970.  Airport Drainage.  Advisory  Circular A/C
     150-5320-5B, FAA, U. S. Department of Transportation,  Washington, DC.

Fenn, D. G. , Hanley, K. J., and DeGeare, T. V.  1975.  Use  of the Water  Balance
     Method for Predicting  Leachate Generation from Solid Waste Disposal Sites.
     EPA/530/SW-168, U. S.  Environmental Protection Agency, Cincinnati,  OH,
     40 pp.

Fouss, J. L.  1974.  Drain  Tube Materials and Installation.   Chapter  8,
     pp 147-177, jn Van Schilfgaarde (1974), q.v.

Foy, C. D., Voight, P. W.,  and Schwartz, J. W.  1980.  Differential Tolerance
     of Weeping Lovegrass Genotypes to Acid Coal  Mine Spoils.  Agronomy
     Journal, 72: 859.

Fuller, W. H. (editor).  1976.  Residual Management by Land Disposal; Pro-
     ceedings of Hazardous  Wastes Research Symposium.  EPA-600/9-76-015,
     Municipal Environmental Research Laboratory, U. S.  Environmental Protec-
     tion Agency, Cincinnati, OH, 270 pp.

Geotechnical Laboratory.  1982.  The Unified Soil Classification System.
     Tech. Memo. 3-357, U.  S. Army Engineer Waterways Experiment Station,
     Vicksburg, MS, (reprint of report originally published 1960).

Gilluly, J., Waters, A. C., and Woodford, A. 0.   1959.   Principles of Geology.
     2nd edition, W. H. Freeman and Co., San Francisco,  534 pp.

Graham, E. H.  1941.  Legumes for Erosion Control and Wildlife.  Misc. Pub.
     412, U. S. Department  of Agriculture, Washington, DC.

Gray, D. H. (chairman).  1977.  Geotechnical Practice for Disposal of Solid
     Waste Materials.  Proceedings, Specialty Conference, Geotech. Eng.  Div. ,
     ASCE, at Ann Arbor, MI, June 1977, Amer. Soc. Civil Engineers, New  York,
     NY, 885 pp.

                                      A-7

-------
Green, W. H.,  and Ampt, G. A.  1911.  Studies on Soil Physics I.  The Flow of
     Air and Water Through Soils.  Jour. Agricultural Sci., Vol. 4, pp 1-24.

Gupta, S. C.,  et al.   1978.  The Agricultural Value of Dredged Material.
     Tech.  Report D-78-36, U. S.  Army Engineer Waterways Experiment Station,
     Vicksburg, MS.

Hafenrichter,  A. L.,  Schwendiman, J. L., Harris, H. L., MacLauchlan, R. S. ,
     and Miller, H. W.   1979.  Grasses and Legumes for Soil Conservation  in
     the Pacific Northwest and Great Basin States.  Agriculture Handbook
     No. 339,  Soil Conservation Service, U. S. Department of Agriculture,
     Washington, DC,  69 pp.

Hald, A.  1952.  Statistical Theory with Engineering Applications.  John  Wiley
     and Sons, Inc.,  New York.

Harr, M. E.   1977.  Mechanics of Particulate Media, a Probabilistic Approach.
     McGraw-Hill Book Co.   Inc., New York.

Harris, D.  H., and Chaney, F. B.   1969.  Human Factors in Quality Assurance.
     John Wiley and Sons,   Inc., New York.

Hart, Fred C. , Associates, Inc.  1980.  Kin-Buc Landfill Remedial Program.
     Project No. 2-8006-01, report to EPA, Region  II, 24 pp.

Haxo, H. E.   1981.  Testing Materials for Use in the Lining of Waste Disposal
     Facilities, pp 269-292 j_n Conway and Malloy (1981), q.v.

Haxo, H., Jr., Dakessian,   S., Fong, M. A., and White, R. M.  1980.  Lining of
     Waste Impoundment and Disposal Facilities.  EPA/530/SW-870C, Municipal
     Environmental Research Laboratory, U. S. Environmental Protection Agency,
     Cincinnati, OH,  385 pp.

Haxo, H. E., Jr., et al.    1983.  Lining of Waste Impoundment and Disposal
     Facilities.  SW-870  (revised).  Government Printing Office, Washington,
     DC.  055-00000231-2.

Heim, G. E., and Machalinski, M. V.  1980. . Characterization of Existing  Sur-
     face Conditions at Sheffield Low-Level Waste  Disposal  Facility.  NUREG/
     CR-1683, U. S. Nuclear Regulatory  Commission, Washington,  DC, 88 pp.

Hilf, J. W.   1970.  Rapid  Compaction Control, pp 502-515 in American Society
     for Testing and Materials (1970),  q.v.

Hilf, J. W.   1974a.  Foundations and Construction  Materials, Chapter V,
     pp  107-204,  i_n U. S.   Bureau of Reclamation (1974a), q.v.

Hilf, J. W.   1974b.  Construction of  Embankments.  Appendix E,  pp  619-644,
      HI  U.  S.  Bureau of Reclamation (1974a),  q.v.

Hilf, J. W.  1974c.  Soil  Mechanics Nomenclature,  Appendix  D,  pp  599-617,
      i_n  U.  S.  Bureau of Reclamation (1974a),  q.v.

                                       A-8

-------
Holdgate, M. N.,  and Woodman, M. J. (editors).  1977.  The Breakdown and
     Restoration of Ecosystems.  NATO Conference Series I, Ecology 3:
     249-278, Plenum, New York.

Holtan, H.  N.  1961.  A Concept for Infiltration Estimates in Watershed
     Engineering.  Agricultural Research Service, U. S. Department of
     Agriculture, Washington, DC.

Holtan, H.  N. ,  et al.  1975.  USDAHA-74 Revised Model of Watershed Hydrology.
     Tech.  Bull.  1518, Agricultural Research Service, U. S. Department of
     Agriculture, Washington, DC.

Horton, R.  E.  1933.  The Role of Infiltration in the Hydrologic Cycle.
     Trans.  Amer. Geophys. Union,  vol. 14, pp 446-460.

Horton, R.  E.  1939.  Analysis of Runoff-Plat Experiments with Varying
     Infiltration-Capacity.   Trans. Amer.  Geophys.  Union, vol. 20, pp 693-711.

Horz, R.  C.   1983.   Applications of Geotextiles to Land Disposal Sites.  Paper
     delivered at Ninth Annual Research Symposium,  Land Disposal, Incineration
     and Treatment of Hazardous Wastes, Cincinnati, OH.

Hough,  B. K.  1969.   Basic Soils Engineering.  2nd edition, Ronald Press,
     New York.

Huggins,  L.  F., and Monke, E. S.  1970.  Mathematical Simulation of Hydrologic
     Events  on Ungaged Watersheds.   Tech.  Report no. 14, Department of
     Agriculture Engineering, Purdue University, W. Lafayette, IN.

Hveem,  F. N.  1957.   Maximum Density and Optimum Moisture of Soils.   HRB
     Bull.  159, pp 1-21,  Highway Research Board, Washington, DC.

Hvorslev, M. J.  1948.  Subsurface Exploration and Sampling of Soils for Civil
     Engineering Purposes.  Research report published by the Waterways Experi-
     ment Station,  Corps  of Engineers, U.  S.  Army,  Vicksburg, MS; subsequently
     republished by the Engineering Foundation, New York, NY, 465 pp.

Hvorslev, M. J.  1949.  Time Lag in the Observation of Ground-Water Levels and
     Pressures.  U.  S. Army Engineer Waterways Experiment Station, Vicksburg,
     Mississippi.

Intergovernmental Methane Task Force.   1979.   Methane from Landfills:  Hazards
     and Opportunities; A Working Symposium.   IMTF:  EPA Region VIII, Colorado
     Department of Health, Tri-County District Health Department, and others,
     Denver, CO.

Israelsen,  C. E., et al.   1980.  Erosion Control During Highway Construction.
     NCHRP  Report 221, Transportation Research Board, Washington, DC.
                                      A-9

-------
Johnson, A. I., and Kunkel, F.  1963.  Some Research Related to Ground-Water
     Recharge - A Progress Report from the U.  S. Geological Survey.  Paper
     presented at Biennial Conference on Ground-Water Recharge and Ground-Water
     Basin Management, University of California, Berkeley, CA, 17 pp.

Johnson, A. I., and Richter, R. C.  1967.  Selected Bibliography on Permeabil-
     ity and Capillarity Testing of Rock and Soil Materials, pp 176-210 jj]
     American Society for Testing and Materials (1967), q.v.

Johnson, A. I.   1981.   Glossary, pp 3-17, i_n Zimmie and Riggs (1981), q.v.

Johnson, A. W. , and Sallberg, J. R.   1960.   Factors That Influence Field Com-
     paction of Soils.  HRB Bull.  272, Highway Research Board, Washington, DC.

Johnson, A. W., and Sallberg, J. R.   1962.   Principal Methods for Determining
     Maximum Unit Weight and Optimum Moisture Content.  JRB Bull.  319, Highway
     Research Board, Washington, DC.

Jones, A.  K., et al.  1982.   Coverings for Metal Contaminated Land.  Proceed-
     ings, Nat.  Conf.  on Management of Uncontrolled Hazardous Waste Sites,
     Washington, DC.

Jorgenson, J.  L.  1969.   Measuring the Variability of Compacted Embankments.
     HRB Record 290, pp 23-34, Highway Research Board, Washington, DC.

Joslin, J. G.   1959.  Ohio's Typical Moisture-Density Curves, pp 111-118, i_n
     American Society for Testing and Materials (1959), q.v.

JRB Associates, Inc.  1982.   Handbook for Remedial Action at Waste Disposal
     Sites.  EPA-625/6-82-006, Municipal Environmental Research Laboratory,
     U. S. Environmental Protection Agency, Cincinnati, OH, 497 pp.
     Note:  this handbook was reprinted as Rogoshewski, Bryson, and Wagner
     (1983), q.v.

Juran, J.  M. (editor-in-chief).  1962.  Quality Control Handbook.   2nd edi-
     tion, McGraw-Hjll Book Co., New York.

Karimi, A. A.   1983.  Studies of the Emission and Control of Volatile Organics
     in Hazardous Waste Landfills.  Unpublished Ph.D. dissertation, University
     of Southern California, Los Angeles.

Kay, B. L.  1976.   Hydroseeding, Straw, and Chemicals for Erosion Control.
     Agronomy Progress Report No.  77, Department of Agronomy and Range
     Sciences,  University of California, Davis, CA, 14 pp.

Kay, B. L.  1978.   Mulches for Erosion Control and Plant Establishment on
     Disturbed Sites.   Agronomy Progress Report No. 87, Agr. Exper. Station,
     University of California, Davis, CA, 19 pp.

Kay, B. L.  1979.   Hydromulching Fibers - What's New?  Agronomy Progress
     Report No.  98, Agr. Exper. Station, University of California, Davis, CA.


                                      A-10

-------
Kays, W. B.  1977.  Construction  of  Linings  for  Reservoirs,  Tanks  and Pollu-
     tion Control Facilities.  Wiley Interscience,  John  Wiley and  Sons,  Inc.,
     New York, 379 pp.

Kerr, K. W. (editor-in-chief).  1981.  Cost  Data for  Landscape Construction.
     Kerr Associates,  Inc. , Minneapolis, MN,  244 pp.

Kirpich, Z. P.   1940.  Time of Concentration of  Small  Agricultural  Watersheds.
     Civil Engineering, v. 10, no. 6.

Krynine, D. P.,  and Judd, W.  R.   1957.  Principles  of  Engineering  Geology  and
     Geotechnics, McGraw-Hill Book Co. Inc.,  New York, 730 pp.

Lambe, T. W.    1951.   Soil Testing for Engineers.  John Wiley and Sons,  Inc.,
     New York.

Lambe, T. W. ,  and Whitman, R. V.  1969.  Soil Mechanics.  John Wiley  and Sons,
     Inc., New York, 553 pp.

Langfelder, L. J., and Nivargikar, V. R.   1967.   Some  Factors  Influencing
     Shear Strength and Compressibility of Compacted Soils.   HRB Record  177.
     Highway Research Board,  Washington, DC.

Lanz, L. J.  1968.  Dimensional Analysis Comparison of Measurements Obtained
     in Clay with Torsional Shear Instruments.   M.S. Thesis,  Mississippi State
     University, Starkville,  MS.

Lee, C.  R., Skogerboe, J. G., Eskew, K., Price,  R. W., Page,  N. R., Clar,  M.,
     Kort, R., and Hopkins, H.  1984.  Restoration of  Problem  Soil  Materials
     at Corps of Engineers Construction Sites.   Instruction  Report  EL-84-1,
     U.  S.  Army  Engineer Waterways Experiment Station, Vicksburg,  MS.

Lee, C.  R., et al.  1976.  Feasibility of the Functional Use  of Vegetation to
     Filter,  Dewater, and Remove Contaminants from Dredged Material.  Tech.
     Report D-76-4,  U. S. Army Engineer Waterways Experiment  Station,
     Vicksburg, MS.

Leonards, G.  A., editor.   1962.   Foundation  Engineering.   McGraw-Hill Book
     Co. Inc., New York,  1136 pp.

Leone, I. A.,  et al.   1979.  Adapting Woody  Species and  Planting Techniques
     to Landfill Conditions.   EPA-600/2-79-128,  U. S. Environmental Protection
     Agency,  Cincinnati,  OH.

Lester,  R.  H., Enrick, N. L., and Mottley, H. E.   1977.  Quality Control for
     Profit.   Industrial  Press,  Inc., New York.

Linsley, R.  K., Jr.,  Kohler, M.  A.,  and Paulhus,  J.  L. H.  1958.   Hydrology
     for Engineers.   McGraw-Hill Book Co.  Inc.,  New York.

Linsley, R.  K., and  Franzini, J.  B.   1979.   Water Resources  Engineering.
     3rd edition, McGraw-Hill Book Co. Inc., New York.

                                      A-ll

-------
Lull, H. W.   1953.  Evapotranspiration:   Excerpts  from  Selected  References.
     Occas. Paper  131, Southern Forest  Experiment  Station,  Forest  Service,
     U. S. Department of Agriculture, New Orleans,  LA.

Lutton, R. J.   1980.  Evaluating Cover  Systems  for Solid  and  Hazardous  Waste.
     SW-867,  Municipal Environmental Research Laboratory, U.  S.  Environmental
     Protection Agency, Cincinnati, OH, 57 pp.

Lutton, R. J.,  Regan, G. L., and Jones, L. W.   1979.  Design  and Construction
     of Covers  for Solid Waste Landfills.  EPA-600/2-79-165,  Municipal  Envi-
     ronmental  Research Laboratory, U.  S. Environmental Protection  Agency,
     Cincinnati, OH, 250 pp.

Lutton, R. J.,  et al.  1982.  Parameters  for Characterizing Sites  for Disposal
     of Low-Level Radioactive Waste.  NUREG/CR-2700, U. S. Nuclear  Regulatory
     Commission, Washington, DC.

Martin.  1978.  See Tolman et al.,  1978.

Martin, A. C.,  Zim, H. S., and Nelson,  A. L.  1951.  American Wildlife  and
     Plants.   McGraw-Hill Book Co., Inc., New York.

Martin, J. P.,  Koerner, R.  M., and Whitty, J. E.   1984.   Experimental Friction
     Evaluation of Slippage Between Geomembranes,  Geotextiles, and  Soils.
     Proceedings, Intl.  Conf. on Geomembranes,  Denver,  CO., June 1984,  vol 1,
     pp 191-196.

McDowell, C.   1972.  Flexible Pavement  Design Guide.  Bull. 327, National
     Lime Association.

McKell, C. M.   1975.  Shrubs - A Neglected Resource of  Arid Lands.  Science,
     187:  803-809.

McMahon, L. A.  (editor).   1979.   1980 Dodge Guide  to Public Works and Heavy
     Construction Costs.   (Published annually), McGraw-Hill Publ. Co.,  New
     York, 221 pp.

Means,  Robert S., Company.   1980.   Building Construction  Cost Data  1980.
     (Published annually), RSM Co., Kingston, MA,  371 pp.

Meyer,  M.  P., and Knight, S. J.   1961.   Trafficability  of Soils  - Soil
     Classification.  Tech. Memo.  3-240,  Supplement 16, U. S. Army  Engineer
     Waterways Experiment Station, Vicksburg, MS.

Middlebrooks, E. J., Jones, N.  B., Reynolds, J.  H., Torpy, M. F., and Bishop,
     R.  P.  1978.   Lagoon Information Source Book.  Ann Arbor Science Pub-
     lishers, Ann Arbor, MI, 215 pp.

Miller, D. E., and Bunger, W. C.  1963.    Moisture  Retention by Soil with Coarse
     Layers in the Profile.  Soil  Sci.   Soc.  Amer.  Proceedings, vol  27,  no. 5,
     pp 586-589.


                                      A-12

-------
Miller, I., and Freund, J. E.  1977.  Probability and  Statistics  for  Engineers.
     2nd edition, Prentice-Hall, Englewood Cliffs, NJ,  529 pp.

Miller-Wardon Associates.  1965.  Development of Guidelines  for Practical and
     Realistic Construction Specifications.  NCHRP Report 17, Highway Research
     Board, Washington, DC.

Mills, W. H.  1970.  Grain Size Analysis of Soil by Elutriation,  pp 88-90,  i_n
     American Society for Testing and Materials (1970), q.v.

Mitchell, J. K.  1976.  Fundamentals of Soil Behavior.  John Wiley and  Sons,
     Inc., New York, 422 pp.

Moore, C. A.  1980.  Landfill and Surface Impoundment  Performance Evaluation.
     EPA/SW-869, Municipal Environmental Research Laboratory, U.  S. Environ-
     mental Protection Agency, Cincinnati, OH.

Mueller-Dombois, D., and Ellenberg, H.  1974.  Aims and Methods of Vegetation
     Ecology.  John Wiley and Sons, Inc., New York.

National Cooperative Highway Research Program.  1979.  Quality Assurance.
     NCHRP Synthesis 65, Transportation Research Board, Washington, DC, 42  pp.

National Oceanic and Atmospheric Administration.  1974.  Climatic Atlas of  the
     United States.  NOAA, U. S. Department of Commerce, Washington,  DC (see
     Table 2.1, this handbook).

Nevada State Conservation Commission.   (No date).   Handbook of Best Management
     Practices,.Non-designated Area Water Quality Management Plan, Loose-leaf
     notebook, Carson City, NV.

Neville, A. M., and Kennedy, J. B.   1964.   Basic Statistical Methods  for Engi-
     neers and Scientists.  International Textbook Co., Scranton, PA.

Nichols, H. L., Jr.  1962.  Moving the Earth:  The Workbook of Excavation.
     2nd edition, North Castle Books,  Greenwich, CT.

Nolan, M. E., Hatano, M. M., Howe11, R.  B. , and Shirley, E.  C.  1976.   Control
     of Ditch Erosion Using Fiberglass Roving.  California Department of
     Transportation, Sacramento, 26 pp.

Nolan, M. E., Spring, R. J., and Howell, R. B.  1978.  Control of Slope Ero-
     sion Using Fiberglass Roving with Vegetation.   California Department of
     Transportation, Sacramento, 92 pp.

Oglesby, C. H.  1975.  Highway Engineering.  3rd edition, John Wiley  and Sons,
     Inc.,  New York, 783 pp.

Olson, R. E., and Daniel, D.  E.  1981.  Measurement of the Hydraulic  Conduc-
     tivity of Fine-Grained Soils,  pp 18-64 vn Zimmie and Riggs (1981), q.v.
                                      A-13

-------
Overton, D.  C.  1964.  Mathematical Refinement of an Infiltration Equation for
     Watershed Engineering.   Agricultural Research Service, U. S. Department
     of Agriculture, Washington, DC.

Parcher, J.  V., and Means, R. E.  1968.   Soil Mechanics and Foundations.
     Merrill Co., Columbus,  OH.

Parker, D.  G., Thornton, S.  I.,  and Cheng, C. W.   1977.  Permeability of Fly
     Ash Stabilized Soils, pp 63-71 j_n Gray (1977), q.v.

Parry, G.  D. R.,  Bell, R.  M., and Jones, A.  K.  1982.   Degraded and Contami-
     nated Land Reuse - Covering Systems, j_n Proceedings, National Conference
     on Management of Uncontrolled Hazardous Waste Sites, Washington, DC.

Peck, R. B., Hanson, W. E.,  and Thornburn, T. H.   1974.  Foundation
     Engineering.  2nd edition,  John Wiley and Sons, Inc., New York, 514 pp.

Price, J.  T.  1978.   Soil  Compaction Specification Procedure for Desired Field
     Strength Response.  Report No. 78-7, Joint Highway Research Project,
     Purdue University, W. Lafayette, IN.

Proctor, R.  R.  1933.  Four Articles on the Design and Construction of  Rolled-
     Earth Dams.   Engineering News-Record, vol. Ill, pp 245-248, 286-289,
     348-351,  372-376.

Rankin, W.  L.   1970.  Organic Matter Content of Soils by Redox Titration,
     pp 286-287 i_n American Society for Testing and Materials (1970), q.v.

Redus, J.  F.,  and Spigolon,  S.  J.  1965.  Model Specifications for Embankment
     and Base Course Construction II.  Proceedings, Highway Conference  on Re-
     search and Development of Quality Control and Acceptance Specifications,
     Vol.  1, pp 459-476, U.  S.  Bureau of Public Roads, Washington, DC.

Ree, W. 0., and Palmer, V. J.  1949.  Flow of Water in Channels Protected by
     Vegetative Linings.  Tech.  Bull. 967, Soil Conservation Service, U. S.
     Department of Agriculture,  Washington, DC, 115 pp.

Richards,  L. A. (editor).   1969.  Diagnosis and Improvement of Saline and
     Alkali Soils.  Agriculture Handbook No. 60,  Science and Education  Admini-
     stration, U. S. Department of Agriculture, Riverside, CA.

Richards,  L. A.,  and Middleton,  L. M.  1978.  Best Management Practices  for
     Erosion and Sediment Control.  FHWA-HD-15-1, Federal Highway Administra-
     tion, Region 15, Arlington, VA.

Rishel, H.  L., Boston, T.  M., and Schmidt, C. J.   1981.  Costs of Remedial Re-
     sponse Actions at Hazardous Waste Sites.  Revised final report EPA-600/
     2-82-035, Municipal Environmental Research Laboratory, U. S. Environ-
     mental Protection Agency, Cincinnati, OH, 144 pp.  Also published  by
     Noyes Data Corp. (1984) as "Costs of Remedial Response Actions at  Uncon-
     trolled Hazardous Waste Sites".
                                      A-14

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Ritchie, J.  T.  1972.  A Model for Predicting Evaporation from a Row Crop with
     Incomplete Cover.  Water Resources Research, vol. 8, no. 5, pp 1204-1213.

Rogoshewski, P., Bryson, H.,  and Wagner, K.  1983.  Remedial Action Technology
     for Waste Disposal Sites.  Noyes Data Corp., Park Ridge, NJ.  500 pp.
     (Reprinted from JRB Associates, 1982; q.v.)

Rovers, F.  A., Tremblay, J. J., and Mooij, H.   1977.  Procedures for Landfill
     Gas Monitoring and Control.   EPS 4-EC-77-4, Waste Management Branch,
     Environment Canada, Ottawa.

Schaake, J.  C., Jr., Geyer, J. C., and Knapp, J. W.    1967.  Experimental Anal-
     ysis of the Rational Method.  Jour. Hyd. Div.,  ASCE, vol. 93, no. HY6.

Schlegel Lining Technology, Inc.   1983.  Quality Control Program for Installa-
     tion of Schlegel Sheet High Density Polyethylene.  The Woodlands, TX.

Schmidt, N.  0.  1970.  Organic Carbon Content of Soil by Wet Combustion,
     pp 271-278 _i_n American Society for Testing and Materials (1970), q.v.

Schmugge, T. J., Jackson, T.  J.,  and McKim, H.   L.  1980.  Survey of Methods
     for Soil Moisture Determination.   Water Resources Research, vol. 16,
     no. 6,  pp 961-979.

Schomaker,  N. B.,  and Murdock, R. F.  1969.  Selection and Placement of Soil
     Cover Material in a Sanitary Landfill.  Open File Report UD-03-68-20,
     U. S.  Public  Health Service, Cincinnati, OH.

Schroeder,  P. R. ,  Gibson, A.  C.,  and Smolen, M.  D.  1984.  The Hydrologic
     Evaluation of Landfill Performance (HELP) Model; Vol. II, Documentation
     for Version I.  EPA/530-SW-84-010, Municipal Environmental Research
     Laboratory, U. S. Environmental Protection Agency, Cincinnati, OH.

Schroeder,  P. R.,  Morgan, J.  M. ,  Walski, T. M.,  and Gibson, A. C.  1984.  The
     Hydrologic Evaluation of Landfill Performance (HELP) Model; Vol. I, User's
     Guide for Version I.  EPA/530-SW-84-009, Municipal Environmental Research
     Laboratory, U. S. Environmental Protection Agency, Cincinnati, OH.

Schwab, G.  0., Frevert, R.  K., Edminster, T. W., and Barnes, K. K.  1981.
     Soil and Water Conservation Engineering.  Third edition, John Wiley and
     Sons,  New York, 525 pp.

Schwartz, A. E.   1967.  Rapid Means of Determining Density and Moisture Con-
     tent of Soils and Granular Materials.  Bull. 109, Engineering Experiment
     Station, Clemson University, Clemson, SC.

SCS Engineers.  1980.  Surface Impoundment Assessment in California.   Report
     prepared under contract no.  68-01-5137, to U. S. Environmental Protection
     Agency, SCS Engineers, Long Beach, CA, 235 pp.
                                      A-15

-------
SCS Engineers.  1981.  Remedial Actions at Hazardous Waste Sites:  Survey and
     Case Studies.  Report prepared under contract no. 68-01-4885, to U. S.
     Environmental Protection Agency, SCS Engineers, Long Beach, CA, 230 pp.

Shafer, R.A.,  Renta-Babb, A., Bandy, J. T., Smith, E. D., and Malone, P. G.
     1984.   Landfill Gas Control at Military Installations.  CERL-TR-N-173,
     U. S.  Army Corps of Engineers, Construction Engineering Research Labora-
     tory,  Champaign, IL.

Shaw, M.  D., and Arble, W.  C.  1959.  Bibliography on Methods for Determining
     Soil Moisture.   Engineering Research Bull. B-78, Pennsylvania State
     University, State College, PA.

Sherard,  J.  L. , and Decker, R. S.  (editors).    1977.  Dispersive Clays, Related
     Piping, and Erosion in Geotechnical Projects.  ASTM Spec.  Tech. Pub. 623,
     American Society for Testing and Materials, Philadelphia,  PA, 486 pp.

Sherard,  J.  L., Dunnigan, L.  P., and Decker,  R. S.  1976.   Identification and
     Nature of Dispersive Soils.  Jour. Geotech. Eng. Div., ASCE, vol. GT4,
     pp 287-301.

Sherard,  J.  L., Woodward, R.  J., Gizienski, S.  F., and Clevenger, W. A.  1963.
     Earth and Earth-Rock Dams.  John Wiley and Sons, Inc., New York, 725 pp.

Sibley, E.  A.  , and Yamane,  G.  1965.  A Simple Shear Test for Saturated Cohe-
     sive Soil.  Proceedings, 5th Pacific Area National Meeting, ASTM,
     Seattle,  WA.

Sisk, S.  W.    1981.  NEIC Manual for Groundwater/Subsurface Investigations at
     Hazardous Waste Sites.  EPA-330/9-81-002,  National Enforcement Investiga-
     tion Center,  U. S. Environmental Protection Agency, Denver, CO, 72 pp
     plus appendices.

Smith,  P. C.  1970.   Rapid Determination of Approximate Moisture Content of
     Soils for Field Control  of Embankment Construction, pp 447-459 j_n Ameri-
     can Society for Testing and Materials (1970), q.v.

Smith,  R. A. H., and Bradshaw, A.  D.  1972.  Stabilization of Toxic Mine
     Wastes by the Use of Tolerant Plant Populations.  Trans. Inst. Win.
     Metal!.,  81 A: 230-237.

Snethen,  D.  R., Johnson, L. D., and Patrick,  D. M.  1977a.  An Investigation
     of the Natural  Microscale Mechanisms that Cause Volume Change in Expan-
     sive Clays.  FHWA-RD-77-75, Federal Highway Administration, Washington,
     DC,  285 pp.

Snethen,  D.  R., Johnson, L. D., and Patrick,  D. M.  1977b.  An Evaluation of
     Expedient Methodology for Identification  of Potentially Expansive Soils.
     FHWA-RD-77-94,  Federal Highway Administration, Washington, DC, 43 pp.

Soil Conservation Service.   1973.   Typical Specifications for Construction  of
     Earth-fill Dams.  Southern Region, SCS,  U. S. Department of Agriculture.

                                      A-16

-------
Soil Conservation Service.  1974.  Hydrology.  Section 4,  National  Engineering
     Handbook, SCS, U. S. Department of Agriculture, Washington,  DC.

Sowers, G. B., and Sowers, G.  F.   1970.  Soil Mechanics and  Foundations.
     3rd edition, Macmillan Co., New York.

Spaine, P. A., Llopsis, J. L., and Perrier,  E. R.   1978.   Guidance  for  Land
     Improvement Using Dredged Material.  Tech.  Report DS-78-21,  U.  S.  Army
     Engineer Waterways Experiment Station,  Vicksburg, MS.

Spangler, M.  G., and Handy, R. L.  1982.  Soil Engineering.  4th  edition,
     Harper and Row, New York.

Spigolon, S.  J., and Kelley, M. F.  1984.  Geotechnical Quality Assurance  of
     Construction of Disposal  Facilities.  EPA-600/2-84-040, Municipal  Envi-
     ronmental Research Laboratory, U. S. Environmental Protection  Agency,
     Cincinnati, OH.

Spooner, P.  A., Wetzel, R. S.  , Spooner, C. E., Furman, C.  A., Tokarski,  E. F.,
     Hunt, G. E., Hodge, V., and Robinson, T.  1984.  Slurry Trench Construc-
     tion for Pollution Migration Control.   EPA-540/2-84-001, U.  S.  Environ-
     mental  Protection Agency, Washington, DC, and  Cincinnati, OH.,  approx.
     240 pp.

Stephenson,  L. M.  1970.  Construction Quality Assurance.  USAE South Atlantic
     Division, Washington.

Strohm, W. E., and Torrey, V.  H.   1982.  Analysis of Field Compaction Data,
     DeGray Dam, Caddo River,  Arkansas, Misc. Paper GL-82-4, U. S.  Army Engi-
     neer Waterways Experiment Station, Vicksburg,  MS.

Taylor, D. W.  1948.   Fundamentals of Soil Mechanics.  John Wiley and Sons,
     Inc., New York, 700 pp.

Telford, W.  M., Geldart, L. P., Sheriff, R.  E.,  and Keys,  D. A.   1976.
     Applied Geophysics.  Cambridge University Press, New  York.

Teng, W. C.   1962.   Foundation Design.  Prentice-Hall, Englewood  Cliffs, NJ,
     466 pp.

Terzaghi, K., and Peck, R. B.   1967.   Soil Mechanics in Engineering Practice.
     2nd edition, John Wiley and Sons, Inc., New York, 729 pp.

Thompson, M.  M.   1979.  Maps for America.  U. S.  Geological Survey,  U.  S.
     Government Printing Office, Washington, DC,  265 pp.

Thornburg, A.  A.   1979.  Plant Materials for Use on Surface Mined Lands.
     TP-157  and EPA-600/7-79-134, Soil Conservation Service, U. S.  Department
     of Agriculture, Washington, DC.
                                      A-17

-------
Thornthwaite, C. W. , et al.  1944.  Report of the Committee on Transpiration
     and Evaporation, 1943-44.   Iran.  Amer. Geophys. Union, vol. 25, part V,
     pp 683-693.

Thornthwaite, C. W., and Mather, J. R.  1955.  The Water Balance.  Publica-
     tions in Climatology, vol. 8, no. 1, Drexel Institute of Technology,
     Centerton, NJ, 104 pp.

Thornthwaite, C. W., and Mather, J. R.  1957.  Instruction and Tables for Com-
     puting Potential Evapotranspiration and the Water Balance.  Publication
     in Climatology, vol.  10, no.  3, pp 185-311, Drexel Institute of Tech-
     nology, Centerton, NJ.

Todd, D. K.  1970.   The Water Encyclopedia.  Water Information Center, Port
     Washington, NY.

Tolman, A.  L.,  Ballestero, A. P.,  Jr., Beck, W.  W. ,  Jr., and Emrich, G.  H.
     1978.   Guidance Manual for Minimizing Pollution from Waste Disposal
     Sites.  EPA-600/2-78-142,  U.  S. Environmental  Protection Agency,
     Cincinnati, OH, 95 pp.

Tomlinson,  M. J.  1969.   Foundation Design and Construction.   2nd edition,
     Pitman, London.

Turnbull,  W.  J., Compton,  J.  R. , and Ahlvin, R.  G.   1966.   Quality Control of
     Compacted Earthwork.   Jour.  Soil  Mech. Found.  Div. , ASCE, vol. 92,
     no. SM 1.

U.  S. Army Engineer Waterways Experiment Station.  1954.  A Study of Moisture
     Content Determinations on Selected Soils.  Misc.  Paper H-73, Vicksburg,
     MS.

U.  S. Atomic Energy Commission.  1969.  Quality Assurance Criteria for Nuclear
     Power Plants.   10 CFR 50,  Appendix B, Washington, DC.

U.  S. Bureau of Reclamation.   1974a.  Design of Small  Dams.  2nd edition,
     U. S.  Government Printing Office, Washington,  DC, 816 pp.

U.  S. Bureau of Reclamation.   1974b.  Earth Manual.   2nd edition, U. S.
     Government Printing Office, Washington, DC, 810 pp.

U.  S. Department of Agriculture.   1937.  Range Plant Handbook.  Forest
     Service, L). S. Department of Agriculture, Washington, DC.

U.  S. Department of Agriculture.   1972.  Landscape for Living:  Yearbook of
     Agriculture.   Washington,  DC.

U.  S. Department of Agriculture.   1973.  Seeding Non-Irrigated Lands in New
     Mexico.  Range Technical Note 60, Soil Conservation Service, Science and
     Education Administration,  Las Cruces, NM.
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-------
U. S. Department of Agriculture,  Forest  Service.   1979.   User  Guide  to  Soils;
     Mining and Reclamation  in the West.  Gen. Tech.  Report  INT-68,  SEAM,
     Intermountain Forest and Range Experimental  Station, Ogden,  UT.

U. S. Department of Agriculture,  Soil Conservation  Service.  1975.   Maryland
     Standards and Specifications for Soil  Erosion  and  Sediment Control  in
     Developing Areas.  College Park, Md.

U. S. Department of Defense.  (No date).  Natural  Resources  -  Land Management.
     Army TM 5-630, Washington, DC.

U. S. Environmental Protection Agency.   1976.  Erosion  and Sediment  Control;
     Surface Mining in the Eastern United States,  Planning.  Vols. 1  and 2,
     EPA-625/3-76-006, U. S. Environmental  Protection Agency,  Washington, DC.

U. S. Environmental Protection Agency.   1982.  Hazardous  Waste Management
     System; Permitting Requirements for Land Disposal  Facilities.   Part II.
     Federal Register, vol.  47, no. 143, pp 32274-32388,  Washington,  DC.

U. S. Nuclear Regulatory Commission.  1982.  Final  Low-Level Waste
     Regulations.   10 CFR 61, Sec. 61.12, pp 94-96, Washington, DC.

U. S. Weather Bureau.   1955.  Rainfall Intensity-Duration Curves.  Tech.
     Paper 25, USWB, Washington,  DC.

Van Schilfgaarde,  J. (editor).  1974.  Drainage for Agriculture.  Monograph 17
     in the Series, "Agronomy."  American Society of Agronomy, Inc.,  Madison,
     WI, 700 pp.

Vieira, S. R., Nielsen, D. R. , and Biggar, J. W.   1981.   Spatial  Variability
     of Field-Measured Infiltration Rate.  Sci. Soc. Amer. Jour., vol. 45,
     pp 1040-1048.

Viessman, W. ,  Jr.,  Knapp, J. W.,  Lewis, G. L., and  Harbaugh, T. E.   1977.
     Introduction to Hydrology.   2nd edition, Harper and  Row,  New York.

Virginia Soil  and Water Conservation Commission.  1980.   Virginia Erosion and
     Sediment Control  Handbook, 2nd ed. , Richmond,  VA.

Visher, S. S.   1954.  Climatic Atlas of the United  States.   Harvard  University
     Press, Cambridge, MA, 403 pp.

Whitman, R. V.   1960.   Some  Considerations and Data Regarding  the Shear
     Strength of Clays.  Research Conference on Shear Strength of Cohesive
     Soils, ASCE,  Boulder, CO, pp 581-614.

Willardson, L.  S.   1974.   Envelope Materials.  Chapter  9, pp 179-196, ui Van
     Schilfgaarde (1974), q.v.

Willenbrock, J.  H.   1976.  A Manual for Statistical Quality  Control  of Highway
     Construction.   Vols. 1  and 2, Purchase Order No. 5-1-3356, Federal High-
     way Administration,  Washington, DC.

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Willenbrock, J. H., and Shepard, S.  1980.  Construction QA/QC Systems:
     Comparative Analysis.  Jour. Construe. Div. ASCE, vol. 196, no. COS,
     pp 371-387.

Wilson, S. D.  1970.  Moisture-Density Relationships of Soil Using Harvard
     Compaction Apparatus, pp 101-103 j_n American Society  for Testing and
     Materials (1970), q.v.

Winterkorn, H. F., and Fang, H.  Y.  1975.  Foundation Engineering Handbook.
     Van Nostrand Reinhold Co.

Woods, K.  B., and Litehiser, R.  R.  1938.  Soil Mechanics  Applied to Highway
     Engineering in Ohio.  Bull. 99, Engineering Experiment Station, Ohio
     State University, Columbus.

Woods, K.  B., Miles, R. D., and Lovell, C. W. , Jr.  1962.  Origin, Formation,
     and Distribution of Soils  in North America.  Chapter  1, pp 1-65, jm
     Leonards (1962), q.v.

Wright, M. J. (editor).  1976.   Plant Adaptation to Mineral Stress in Problem
     Soils.  Cornell University Agricultural  Experiment Station, Ithaca, NY.

Zimmie, T. F., and Riggs, C. 0.  (editors).  1981.  Permeability and Ground-
     water Contaminant Transport.  ASTM Spec. Tech. Pub. 746, American  Society
     for Testing and Materials,  Philadelphia, PA, 251 pp.
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                                  APPENDIX B

                                CASE HISTORIES
    Case histories can convey valuable information to the cover designer, as
they record actual experience, including problems that arise and their
solution.  Unfortunately to date not many cover systems have been designed and
built at uncontrolled hazardous waste sites.

    Two cases of recently installed cover systems at hazardous waste sites
whose details were available to the preparers of this Handbook are presented
here.  These are the Sylvester hazardous waste site, near Nashua, NH, and the
Kin-Buc sanitary landfill, in Edison Township, Middlesex County, NJ.

    The cover designer wishing to investigate performance histories of estab-
lished waste-site covers may consult documentation of low-level nuclear waste
repositories, of which there are approximately a half dozen in the U. S., and
of closed municipal landfills, of which there are many.   Experience from such
sites will be relevant in varying degrees for uncontrolled hazardous waste
sites, since, particularly at municipal waste sites, covers have been called
upon to perform various functions other than acting as an impermeable roof.
Demonstrated problems at such sites have included, prominently, subsidence due
to collapse of buried containers and erosion due to a variety of specific
causes.
B.I Sylvester Hazardous Waste Site


    The Sylvester hazardous waste site, about 20 acres in size, is located on
Gil son Road about three miles west of Nashua, NH.   The New Hampshire Water
Supply and Pollution Control Commission, pursuant to a cooperative agreement
with the USEPA, contracted for site investigations and for remedial-action
design and construction.   The latter was carried out during the summer and
fall of 1982.

    Extensive site investigations including ground-water sampling, pumping
tests, surface-water sampling, water-quality analyses, borings, test pits, and
magnetometer surveys were performed.   The presence of high levels of tetrahy-
drofuran, methylene chloride, and toluene, as well as other volatile organic
compounds, was established.  It was known that demolition debris, including
stumps and timbers, had been buried at the site along with hazardous wastes.
Over 1300 drums were removed from the site, but others were believed likely to
be still buried.

                                      B-l

-------
    The local geology comprises glacial sands, silts, and gravels, overlying
schist bedrock at depths of about 30 to 100 ft.   Impervious soils are rare in
the area.   Mean monthly temperatures range between 22°F (January) and 70°F
(July); mean annual precipitation approximates 40 inches.

    A bentonite-slurry trench (wall) was installed to bedrock completely
enclosing the site.  Site topography was modified by leveling several small
prominences.  The wastes were covered with a minimum thickness of 3 ft of
local soil placed in 6-in.  lifts and compacted with vibratory rollers to at
least 95 pet of Standard Proctor maximum density.  On the compacted surface
was laid a 40-mil HOPE geomembrane.   The roll width of the membrane was
22.5 ft, and adjoining strips were heat-bonded with lap joints.   The membrane
material showed approximately 500 pet elongation before failure.   The membrane
was laid over the top of the slurry wall and anchored with a V-shaped anchor
trench around the periphery.   The membrane was then covered with 3 ft of local
soil, moderately compacted.  Upon this was laid a 4-in. layer of "loam" or
topsoil, which was seeded with a specified mixture of grasses and legumes.

    Where exploration had indicated the maximum concentrations of decayable
buried material, gas vents were installed, consisting of vertical PVC pipes
perforated beneath the membrane, protruding 3 ft above final grade, and capped
with activated-carbon gas adsorbers.  Design details of these and other fea-
tures are shown in Figures B-l-B-4,  and views of the site during construction
are shown in Figures B-5-B-7.  Shafts for the gas-vent pipes were drilled with
an auger through holes cut in the membrane; the joint between pipe and membrane
was sealed with a flange connection as shown in Figure B-4.   It was necessary
in some places to stabilize the top of the slurry wall by laying a geotextile
over it.  A view of the geotextile,  a nonwoven polyester,  can be seen in
Figure B-7.

    The final grading plan called for cut slopes along the site boundaries as
steep as 52 pet in places,  and slopes over the cover of 3 to about 11 pet.   A
separate mix of grasses and legumes was specified for sloping areas.   Around
most of the perimeter a 15-20 ft wide flat was placed just outside the slurry
wall.  This can be driven on by vehicles.   Also, being slightly canted outward
toward the cut slopes, it acts as a de facto ditch, intercepting surface
runoff from the slopes.

    In the first few months since cover completion, the system has performed
well for the most part but has experienced some erosion problems in swales
from runoff when the soil above the membrane was saturated (Tom Roy, NHWSPCC,
personal communication, 21  April 1983).  Also there have been some erosion
problems where subsurface water exits at the edge of the membrane.

    A tabulation of the bid figures for remedial construction at the Sylvester
site is presented in Table B-l.
                                      B-2

-------
                           FIGURE B-l




              CAP  DETAIL,  SYLVESTER SITE (N.T.S.)
                       3 °/0  •bLOPfc  /MM.
                                       F   f
                           FIGURE B-2




DETAIL OF MEMBRANE  CAP  AT SLURRY WALL, SYLVESTER SITE  (N.T.S.)
                                                F-ETNCfc
         HM GEAOfc-
                               B-3

-------
                       FIGURE  B-3

      GAS VENT DETAIL,  SYLVESTER SITE (N.T.S.)
                                               ev
                                       /AlN CiED.

                                      -T V  .w ___
                10'
                                i" f>f:Z.f-.
                                                —^
                       FIGURE  B-4

 DETAIL OF  SEAL OF  MEMBRANE  CAP AROUND PIPE  (N.T.S.)
UOL£ IM  PiTcH
-run.)j PiPt OVA.
     fife "if
          OJMT  P&TCU <
            IM  UMlkjC,
                           B-4

-------
                         FIGURE  B-5

  GEOMEMBRANE  BEING  LAID  AT  SYLVESTER  HAZARDOUS WASTE  SITE,
        STRIP  WIDTH  IS  22.5  FEET,  THICKNESS  40 MILS,
         MATERIAL  HOPE.   NOTE  LAPPED SEAM AT RIGHT.
                        FIGURE B-6

GAS VENT PIPES PROTRUDING THROUGH 3-FT-THICK LAYER OF SOIL
 PLACED OVER GEOMEMBRANE, SYLVESTER HAZARDOUS WASTE SITE
                            B-5

-------
                    FIGURE B-7

GEOTEXTILE LAID OVER SLURRY WALL FOR REINFORCEMENT.
 GEOMEMBRANE WILL BE LAID OVER GEOTEXTILE.   BROOK,
 MIDDLE DISTANCE, RECEIVES LOCAL SURFACE DRAINAGE.
                        B-6

-------
                                                                 TABLE  B-l
                                BID  TABULATION FOR CAP AND CONTAINMENT.WALL CONSTRUCTION AT THE
                                  SYLVESTER  SITE,  NASHUA,  NEW HAMPSHIRE  (SLURRY TRENCH METHOD)
        Prepared July 26, 1982
      GHR Engineering Corporation
        75 Tarkiln Hill Road
       New Bedford, MA   02745


Clearing and Grubbing
Removal of Existing
Pipe (0-24")
Fence Removal for
Re-Use or Storage
Common Excavation
Unclassified Excavation
Embankment-ln-Place
Fine Grading
Stockade Screen Fence
Chalnllnk Fencing
with Aluminum
Coating
Post Assemblies
for 8' High Chalnllnk
F«nce
Est. Qu

15
50
2217
145,000
1
145,000
1
1376
2100
8
entities
Unit of
Acre
l.f.
l.f
c.y.
c.y.
c.y.
Unit
l.f
1,
each

Bid A i Bid B Bi
$ 2,800.00 1 $ 42,000.00 : $ 3,500.00 $ 52,500.00 $ 3,000.00
1
50.00 2,500.00 40.00 2,000.00 20.00
5.00 11,085.00 8.00 17,736.00 2.50
1.40 203,000.00 1.80 261,000.00 1.60
200.00 200.00 50.00 50.00 100.00
0.35 50,750.00 1.37 198,650.00 0.75
50,000.00 50,000.00 6,800.00 6,800.00 12,000.00
9.50 13,072.00 9.45 13,003.20 12.50
11.25 23,625.00 12.29 25,809.00 17.25
160.00 1,280.00 100.00 800.00 175.00

d C
$ 45,000.00
1,000.00
5,542.50
232,000.00
100.00
108,750.00
12,000.00
17,200.00
36,225.00
1,400.00

Bl
» 2,500.00
24.00
1.50
1.08
6.00
0.37
83,650.00
13.62
13.44
95.60

d D
* 37,500.00
1,200.00
3,325.50
156,600.00
6.00
53,650.00
83,650.00
18,741.12
28,224.00
764.80

Bl
1 3,600.00
30.00
2.75
1.90
20.00
0.35
75,000.00
12.30
12.50
85.00

d E
$ 54,000.00
1,500.00
6,096.75
275,000.00
20.00
50,750.00
75,000.00
16,924.80
26,250.00
680.00
CCT
           Courtesy of New Hampshire Water Supply and Pollution Control Commission
                                                                                                                           (Sheet 1 of 3)

-------
                                               TABLE B-1  (Continued)
Itos of Work
20' Wide Chain! Ink
Gates
Resetting Railings
and Fences
toaa 4" Deep
Lines tone
Fertilizer for
Initial Application
Fertilizer for
Refertlllzatlon
Park Seed Type 12
(pis vt)
Slope Seed Type 33
(pis vt)
Crovnvetch Seed
(pis vt)
Mulch
Est. Quantities
Quantity
1
2217
120,520
48
8,000
16,000
1,160
210
30
5
Unit of
Measurement
each
l.f.
s.y
ton
Ib
Bid A
Unit Price
» 1,000.00
3.75
0.85
100.00
0.25
Ib 0.25
Ib
Ib
Ib
6.00
6.00
20.00
Total Amount
$ 1,000.00
8,313.75
102,442.00
4,800.00
2,000.00
4,000.00
6,960.00
1,260.00
600.00
Bid B
Unit Price
» 700.00
4.83
0.81
141.67
0.20
0.20
5.00
5.25
18.00
Total Amount
$ 700.00
10,708.11
97,621.20
6,800.16
1,600.00
3,200.00
5,800.00
1,102.50
540.00
Bid C
Unit Price
» 750.00
7.00
0.80
125.00
0.05
0.05
7.00
7.00
35.00
acre 500.00 2,150.00 300.00 1,500.00 500.00
Total Amount
* 750.00
15,519.00
96,416.00
6,000.00
400.00
800.00
Bid D
Unit Price
* 320.00
7,05
0.78
160.00
0.22
0.24
8,120.00 5.60
1,470.00 : 5.70
1,050.00 19.20
2,500.00 408.00
Total Amount
» 320.00
15,629.85
94,005.60
7,680.00
1,760.00
3,840.00
6,496.00
1,197.00
576.00
2,040.00
Bid E
Unit Price
$ 200.00
5.90
0.70
135.00
0.18
0.20
4.65
4.75
18.00
340.00
Total Amount
$ 200.00
13,080.30
84,364.00
6,480.00
1,440.00
3,200.00
5,394.00
997.50
540.00
1,700.00
DO
 I
00
                                                                                                               (Sheet 2 of 3)

-------
                                                 TABLE B-l  (Concluded)

Hatting for Erosion
Control
Haybales

Erosion Control (pis wt)
Gas Vents
SUB-TOTAL (All Items
Above)
Cutoff Wall Construction
Replacement of Contami-
nated Soil
Cash Allowance for
Verification Testing
by Engineer
Synthetic Membrane
CONTRACTOR'S TOTAL
BID PRICE
MATHEMATICAL TOTAL
Est. Quantities
Quantity
7300
100
100
11
—
Unit of
s.y.
each
Ib
each
~
204,000 s.f.
7000
"
96,464
c.y.

s.y.
Total of Items 10,306.1,
306.2, 306.3, 5 309

Bid A Bid B
$ 1.25
5.00
3.00
350.00
$ 9,325.00
500.00
300.00
3,850.00
545,162.75
5.64
6.00
1,150,560.00
42,000.00
$50,000.00
4.50
434,088.00
2,221,810.80
2,221,660.75
$ 1.42
10.00
2.50
520.00
$ 10,366.00
1,000.00
250.00
5,720.00
725,256.17
4.50
3.50
918,000.00
24,500.00
$50,000.00
5.30
511,259.20
2.229,015.37
Same
Bid C
* 2.75
12.00
7.50
500.00
$ 20,075.00
1,200.00
750.00
5,500.00
619,767.50
5.44
5.00
1, 109,760,00
35,000.00
$50,000.00
5.00
482,320.00
2,296,842.50
2,296,847.50
Bid D*
$ 1.00
4.80
2.40
600.00
$ 7,300.00
480.00
240.00
6,600.00
531,825.87
7.10
3.42
1,448,400.00
23,940.00
$50,000.00
4.84
466,885.76
2,521,051.50
2,521,051.63
Bid E
$ 0.90
2.00
2.00
500.00
$ 6,570.00
200.00
200.00
5,500.00
636,087.35
7.35
13.70
1,499,400.00
95,900.00
$50,000.00
4.60
443,734.40
2,725,121.70
2,725,121.75
03
ID
                                                                                                              (Sheet 3 of 3)

-------
B.2 Kin-Buc Landfill
    The Kin-Buc sanitary landfill is located in Edison Township, Middlesex
County, New Jersey, near the towns of Highland Park and Metuchen and just
north of the Raritan River.   The landfill  is actually a mound composed of
succeeding layers of wastes, all above original ground level.   The geology at
the site comprises a marine tidal marsh adjacent to the Raritan River, adjoin-
ing and overlying a permeable sand and gravel  formation which dips southward
beneath the river.  Mean monthly temperatures  in the area range between about
31°F (January) and 76°F (July); mean annual  precipitation approximates
41 inches.

    During the period 1973-1976, 70 million  gallons of chemicals were dumped
at the site (Fred C.  Hart Associates, 1980).   A set of environmental problems
developed,  and a lawsuit led to the withdrawal of the site's operating permit.
Resolution of the lawsuit required as a first  step the capping of the landfill,
which was accomplished in 1980.  It was expected that capping would mitigate
the 1eachate-outflow problem.

    The Kin-Buc landfill is approximately  20 acres in size and has roughly the
shape of a mesa, with a flat top and sloping sides.   The cover design consisted
of regrading the top, placing a 12-in.  layer of compacted clay overlain by a
synthetic membrane, overlaying this with a 6-in.  layer of sand, and finally
placing a 12-in. layer of soil suitable for  supporting vegetation.   A carefully
planned drainage system was incorporated.   Around the edge of the top area a
berm was constructed; just inboard of the  berm is a drainage ditch with a
perforated subdrain pipe buried beneath it.   The ditches lead to downchutes
located at three corners of the top area.   The downchutes incorporated gabions
in their construction and discharge to stilling basins, thus conveying water
to the lower level without erosion.

    The side slopes of the landfill  are graded to a slope of about one in
three.   Capping of the slopes consisted of placing a layer of compacted clay,
6 to 12 in.  thick, over the compacted wastes,  and then covering the clay with
12 in.  of soil suitable for supporting vegetation.   Soil might slide off a
membrane placed on slopes as steep as these.   Near the base of the slopes a
drainage ditch system with an outlying berm  was designed to carry off the
surface water flowing down the slopes.

    Four gas vents were installed in the top of the landfill.   These consisted
of vertical  PVC pipes the lower portion of which was perforated and set in a
gravel-packed well in the wastes.

    Figure B-8 is a plan view of the Kin-Buc landfill showing the layout of
the drainage system.   Various detailed aspects of the system are shown in
Figures B-9-B-15.  One of the downchutes may be seen in Figure B-16.

    The drainage system is reported to have  worked well to date (G. Tawadros,
EPA Region II laboratory, personal communication).   The only problem has been
a certain amount of rill erosion on the slopes (Figure B-17).   These rills are
periodically filled and reseeded in an ongoing maintenance program.

                                      B-10

-------
00
                                                                   FIGURE  B-8
                                     PLAN VIEW  OF  KIN-BUC  LANDFILL,  SHOWING  DRAINAGE  SYSTEM
                      A/
                                                                                        LEGEND
                                                                              350  POINT ELEVATION (FEET. M.S L)
                                                                             —— GRASS-LINED SURFACE-WATER
                                                                                   COLLECTION DITCH WITH BERM
                                                                                   AND SUBDRAIN
                                                                             == DOWN CHUTE
                                                                             = = = STONE-LINED CHANNEL
                                                                                   CONCRETE STILLING BASIN
                                                                                   GAS VENT
 TO
RIVER

-------
                            FIGURE  B-9


    EDGE  OF TOP AREA,  DITCH AND BERM,  KIN-BUC LANDFILL


            SLOPE TO Be WOT GREATER THAW 5%  NOR
            LESS  THAN 3%
                                     HOLDGRO EROSION-
                                     CONTROL FABRIC
                                     OR EQUIV
                                                       PERFORATED
                                                       ADS PIPE
                                                       DRAIN GUARD
                                                        EOUIV.
                               4NP COUECTION PITCH  PETAIU
                                   H. T.S.
                            FIGURE  B-10

             DOWNCHUTE  SECTION,  KIN-BUC LANDFILL
6" MlH. COMPACTEP CLAY   M>»X. PE»M«A»IL> TT t - IO"7 CM/»«C
     DOWNCHUTE  SECTION
 NOTES

I. CMANMf L SECTION T9 »t COWSTKuCrCO
 or  GABIOMS Sfmes 32* MAMUFACTURCD

 •Y MACCAFERRI GABIONS, INC. OK EQUIV.

2. Size or STONE FILL TO BC *•" HIM.

3. SIZE OF GABIONS  WITH CHANNEL SECTION

 TO BE  6'-6" x 3'-3" « l'-0'
                                 B-12

-------
                        FIGURE  B-ll

   COVER SOIL  SECTION,  TOP AREA, KIN-BUC LANDFILL
                                  j.
                      \Z* SOIL SUITABLE FOR
                      VEGETATIVE SUPPORT
                      6" SAND
                                         20-MIL PVC LINER-'

                       12* COMPACTED CLAY
                       MAX. PERMEABILITY   / x IO~7  CM/SCC
                       SOIL, USED FOR RCGRADING
                 FINAL COVER FOR TOP SURFACE
                            M.T. s.
                        FIGURE  B-12

COVER  SOIL SECTION,  SIDE SLOPE AREA,  KIN-BUC LANDFILL
                   12" SOIL. SUITABLE  FOR
                   VEGETATIVE SUPPORT
                   MINI, f," COMPACTED CLAY
                   MAX. PERMEABILITY  I " IO~7
                             SOLID WASTE.
                FINAL COVER FOR SIDE SLOPES
                           N.T.S.
                             B-13

-------
                FIGURE B-13

   GAS VENT DETAIL, KIN-BUC  LANDFILL
     COUPLING SOCKET •
              SAND
    4" PVC fuse* (soup)
    SCHED. 4O 	
       IZ" COMPACTED CLAY
1/2."-
      STOME
4*PEKFORATED PVC
SCUED. <4O 	
4* PVC
                           iz" SOIL SUITABLE
                         V
                               20-MIL PVC LIWER
                               GLUED TO RISIR Pire

•n  SOIL
!
                                         FOR
                                H  COMPACTED
                                5  SOLID
                                in
           DETAll.  OF CAS  VENT
                     N.T. S.
                     B-14

-------
                                  a* PECFOKATED

                                  ADS
                                    OK CQUlV.
                                                     FIGURE B-14

                                     GRASSED CHANNEL SECTION, KIN-BUC LANDFILL
                                                           a'-o'
                                                     UoUGRO EROSION-.
                                                     CONTROL FABRIC  o

                                                     -0*
                                                                                                   GROUMP
                                                     FIGURE B-15

                                     SIDE-HILL  DITCH AND BERM, KIN-BUC LANDFILL
oo
i
en
FINISHED

SLOPE
                                                            JO-O  MiM.
                                                               SLOPE
                                                                        PER
                              8"PERFORATE
                              PRAINGUARD
                              EQUIVALENT

                            SLOPE I/Z"PFR FT-*-
                                   D  ADS
12" 5O11- SOITABL6 FOR  VEG.


      12" COMPACTED  CLAY
                                                                        COMPACTED
                                                                            SOIL.
                                                                                  EXlSTIMG GROUND

-------
               FIGURE
         B-16
DOWNCHUTE AT
ONE CORNER OF
                           K1N-BUC LANDFILL
      RILL


                                B-16

-------
                                  APPENDIX C

                                     COSTS
    It has not been feasible to prepare a complete discussion of costs for
cover-system design and construction.   A good example of such a discussion is
Chapter 7 of Spooner et al. (1984), which treats in detail the major cost
elements for slurry-trench design and construction.  Since several problems
and activities are common to the construction of slurry trenches and covers,
it is recommended that the cover designer consult this reference.

    In an effort to develop usable cost information for Superfund remedial-
response actions, Rishel, Boston, and Schmidt (1981) performed a detailed
conceptual study of the costs of remedial measures at landfills and surface
impoundments.   They identified 35 "unit operations" (UO), 21 for landfills and
14 for impoundments.   Examples of UO would be "Ponding" and "Sheet Pile Cut-Off
Wall."  Each UO was analyzed into its components, and these were then costed
for the specific case of Newark, NO, and also for estimated lower-average and
upper-average costs for the U. S.  Both Capital and Operation-and-Maintenance
(O&M) costs were considered.  A wealth of cost information was developed (in
terms of mid-1980 dollars).

    The tables listed below are from Rishel, Boston, and Schmidt (1981).   The
cover designer should be able to recognize those items that pertain to cover
systems.


    Table No.                               Title
       C-l            Capital and O&M Components Which Contribute to
                         Unit Operations
       C-2            Average U.  S.  Low and High Costs of Unit Opera-
                         tions for Medium-Sized Sites (Metric Units)*
       C-3            Landfill Capital  Cost Components - Metric Units
       C-4            Landfill O&M Cost Components - Metric Units
       C~5            Surface Impoundment Capital Cost Components -
                         Metric Units
       C-6            Surface Impoundment O&M Cost Components -
                         Metric Units
   Rishel, Boston, and Schmidt present equivalent tables in English units,  but
  list cost-data sources only in their Metric tables.   For this reason the
  Metric tables have been reproduced here.

                                      C-l

-------
    The cover designer will find this report instructive, and it is highly
recommended.  The authors offer a distinct caveat regarding use of their cost
figures, however, and it is considered appropriate to reproduce it here
(Rishel, Boston, and Schmidt, 1981, p 3):

         "QUALIFICATIONS AND LIMITATIONS OF RESULTS
         "The overall objective of this study was to estimate the cleanup
    costs of hazardous-waste sites using a conceptual-design approach.  This
    approach was necessitated by the fact that "Superfund" remedial-response
    activities are still in their infancy, and that real-world feedback on the
    cost of these hazardous-waste cleanup activities is largely unavailable.
         "In using these cost estimates, the reader should exercise consider-
    able caution.  Cost estimates are only as complete as the unit operations
    they describe, or as realistic as the various assumptions and site profiles
    upon which they are based.
         "A subsequent volume to this report will use real-life experiences in
    actual hazardous-waste-site remedial actions to refine this volume's
    costing methodology."

    The cover-system designer considering the importation of bulk materials
will find an informative discussion of the economics of bulk shipments by
various modes of transportation in Collins and Miller (1976, pp 241-267).

    The actual bid figures for remedial construction at the Sylvester hazardous
waste site, Nashua, NH, are presented in "Case Histories" (Appendix B).

    A table of year-to-year cost indices is presented in Appendix C of JRB
Associates, Inc. (1982).
                                      C-2

-------
                                                    TABLE C-l



                         CAPITAL AND O&M COMPONENTS WHICH CONTRIBUTE TO UNIT OPERATIONS

LANDFILL

1
\ Components
Unit Operations \
1. Contour grading
2. Surface sealing
3. Revegetation
5 . Grout curtain
6. Sheet piling wall
7. Grout bottom sealing
8 . Drains
9. Well point system
10- Deep well svstem
11 . Injection
12. Subgrade Irrigation
13. Chemical fixation
14. Chemical injection
15 . Excavat ion/burial
16 . Ponding
17 . Trench construction
19. Ground water treatment
20. Gas control-passive
21. Gas control-active

22. Pond cloaure/gradinR
24. Revegetation
25. Slurry trench
26. Grout curtain
27. Sheet piling wall
28. Grout bottom seal
29. Tee and Underdrains
30. Well point system
31. Deep well system
32. Well injection
34. Berra reconstruction
35. Excavation/disposal

a












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O&M COSTS
o
 I
to

-------
                                                     TABLE C-2



           AVERAGE U.  S. LOW AND HIGH COSTS OF  UNIT OPERATIONS FOR MEDIUM-SIZED SITES - METRIC UNITS
o
 I



1.
2.

3.



6.
7.
8.



12.

13.
14.
15.

Unit Operations
Contour grading and sur-
Bituminous concrete
surface sealing
Revegetation

cutoff wall

Sheet piling cutoff wall
Grout bottom sealing
Drains
11


Leachate recirculation by
subgrade irrigation
Chemical fixation
Chemical injection
Excavation and reburial


Site
Site

Site



Wall
Site
Pipe



Site

Site
Typical
Metric Units
area, ha
area, ha

area, ha
m2

2
face area, m
area, ha
length, m
rcept face area m2
rcept face area m2
2
area, ha

area, ha
Landfill volume, m
Landfill volume, m
Initial First
Capital Year OSM
$
15,300
67,300

3,450
54.5


73
5,282,000
72.7
62 5
11 6

5,270

69,100
1.67
116
*
114
0

105
0.802

0.80
0
1,600
33.7
5.23
2. 1

1,700

1,600
.0577
0.015

Cost
$
16,300
67,300

14,300
61.2

937
73
5,296,000
357
107
28.6
1,760
19,700

82,500
2.16
116

Capital
$
17,900
92,700

16,500
96.1

1.209
108
10,209,000
106
105
18.3
90
8,360

130,000
3.28
120

First
Year OSM
$
240
0

185
0.877

0.88
0
1,750
36.8
6.64
2.22
201
1,850

1,750
.0631
0.016

Life Cycle
Cost
$
19,900
92,700

18,100
103

1880
108
10,224,000
416
153
37.2
1,785
24,000

145,000
3.81
120
                                                     (Continued)
                                                                                                  (continued)

-------
                                                                       TABLE  C-2   (Concluded)
                                                                                          Average  U.S. L
                                                                                       Initial
                               Unit Operations
                                                                Typical
                                                              Metric Units
o
en
16.   Ponding                       Site area, ha

17.   Trench construction           Trench length, m

18.   Perimeter gravel              Trench length, m
     trench vents

19.   Treatment of contaminated     Contaminated water,  1/d
     ground water

20.   Gas migration control -       Site perimeter, m
     passive

21.   Gas migration control -       Site perimeter, m
     active

22.   Pond closure and contour      Site area, ha
     grading  of surface

23.   Bituminous concrete surface   Site area, ha
     sealing  of closed
     impoundment

24.   Revegetation                  Site area, ha

25.   Slurry trench cutoff wall     Wall face area, m

26.   Grout curtain                 Wall face area, m

27.   Sheet piling cutoff wall      Wall face area, m

28.   Grout bottom seal             Site area, ha

29.   Toe and  underdralns           Pipe length, m

30.   Well point system             Intercept face area, m

31.   Deep well system              Intercept face area, m

32.   Well injection  system         Intercept face area, m

33.   Leachate treatment            Contaminated water,  L/d

34,   Berm reconstruction           Replaced berm, m

35.   Excavation and  disposal       Impoundment volume,  m
     at secure landfill
 Capital
    $

    647

     12.2

     99.2


      1.52
    113


 26,900


 48,500



  2,540

     60.1

    326

     76.8

868,000

    316

     62.3

     33.2

     31.3

      1.16

      2.98

    260
                                                                             Year O&M
                                                                                 $
                                                                                                        0.813


                                                                                                        6.36


                                                                                                    1,070
   171

     0

     1.94

     2.11

18,500

   146

    32.5

     9.59

     9.22

     0.391

     0.122

     0
                                                                                                                 Life Cycle
                                                                                                                    Cost
     647

       15.11

     100


        2.52


     168


     167


   35,900


   48,500



    3,970

       60.1

     343

       94.6

1,024,000

    1,550

     321

     114.4

      109

        4.49

        4.00

     260
                                                                                                                                  Average U.S.  High Cost Per Unit
                              Initial
                              Capital
                                 $
                                                                                                                                      2.57
      173


   35,100


   70,700



    3,820

      105

      631

      115

1,621,000

      609

      117

       60.3

       66.6

        1.96

        3.80

      268
    First
  Year  O&M
     $

     0

     0.710

     0.257


     0.214


     1.71


    12.4


 2,180
   192

     0

     2.12

     2.31

20,200

   160

    33.2

    10.4

    10.1

     0.730

     0.246

     0
Life Cycle
   Cost
    »
   1,028

      20.32

     146


       4.38


     256


     279


   63,500


   70,700



   5,450

      105

     649

      135

1,792,000

    1,960

     398

      149

      141

        6.14

        5.85

      268

-------
              TABLE C-3



LANDFILL CAPITAL COST COMPONENTS - METRIC UNITS
Component
Apply stabilized waste
Area preparation
Backfill
Backfill
Bentonlte, delivered

Bern construction
Blower
Butterfly valves, 6"
Butterfly valves, 8"
Cement pipe, 4"
perforated
Cement pipe, 4"
perforated
Cement pipe , 6"
perforated
Cement pipe, 6"
perforated
Cement pipe, 6"
Chemicals

Deep wells, 6"
Dewaterlng system


Discharge pipe, 4"
Discharge pipe, 4"
Subcomponent
Installation

Labor
Equipment
Materials/shipping

Materials/instal lation
Materials /installation
Materials/installation
Labor

Materials

Labor

Materials

Labor
Materials

Materials/labor
Materials/labor


Labor
Materials
Metric
Definition Units
Hauling and spreading, 10 miles $/m
(16 km), round trip

Dozer and sheepsfoot roller $/m
Dozer and sheepsfoot roller $/m
Shipment of bentonite by rail $/tonne

Use scraper S/m
Blower, air I/each
PVC valve $/each
Asbestos, Class 4000 underdrain $/m

Asbestos, Class 4000 underdraln $/m

Asbestos, Class 4000 underdrain $/m

Asbestos, Class 4000 underdrain $/m

Cement pipe, non-perforated $/m
Treatment chemical, sodium hydrochlorite $/l
(NaCIO)
Drilled and cased $/m
For cost breakdown, see "Discharge
pipe," "submersible pump," "Deep
wells"
PVC plastic, Schedule 40 $/m
PVC plastic, Schedule 40 $/m
Source
Means 1980
Dodge 1980
Dodge 1980
Means 1980
Means 1980
Burlington
Northern 1980
Dodge 1980
Britton 1980
Godfrey 1980
Godfrey 1980
Means 1980

Means 1980

Means 1980

Means 1980

Means 1980
Means 1980
Purex 1980

Means 1980



Means 1980
Means 1980
Cost
8.
741
222
76

0.61
1.44


0,
1,150
192
304


,50


3.00

5

3

8

.3
6
0

20



22
9

.08

.10

.00

.54
.23
.16

.9



.0
.15
Low
5.
469
222
0.
1.
66.

0.
800
135
213
52

,32
.44
.4

.35


1.90

3

1

6

2
4 	

.91

.95

.16

.23
. flo
0.12

14



13
7

.6



.9
.05
High
11.
963
222
0.
1.
177

0.
1,360
230
360
3.

5.

4.

8.

4.
6.
0.

25,



28
6

64
44


60


.18

,38

.06

,48

.63
.60
.17

.1



.8
9.70
Newark
10.
839
222
0.
1.
166

0.
1,200
200
317
2.

4.

3.

7,

4.
5,
0,

21,



25
8.
0

58
44


,52


,82

.77

.53

.52

.04
.85
.15

.8



.1
.60
                                                           (Sheet 1 of 5)
                                                      (continued)

-------
                                               TABLE  C-3  (Continued)

Component
Discharge pipe, 8"

Discharge pipe, 8"
construction
Drilled holes, 2.5"
Drilled holes, 6"
Drill rig
Excavation, drainage
trench
Excavation, drainage
trench
Excavation/grading, soil

Excavation/grading, soil

Excavation, grading , and
recontouring of site
o
1 Excavation, grading and
*"-J recontouring of site
Exploratory boring


Flow meters, 8"

Geotechnical investi-
gation


Grout curtain

Subcomponent
Labor

Materials
Materials/installation
Materials/installation
Rental (Equip. /labor)
Tabor

Materials

Labor

Equipment

Labor


Equipment

Materials/installation




Labor /materials



Labor
Metric
Definition Units
PVC plastic, Schedule 40 J/m

PVC plastic. Schedule 40 J/ir
Drilled and cased with pipe $/m
Drilled and cased with pipe $/m
Crew and light duty rig, and grading I/day
Use backhoe loader $/m

Use backhoe loader $/n

Excavation/grading, soil, common $/IP
borrow, 1000 ft (305 n) haul
Excavation/grading, soil, common l/m
borrow, 1000 ft (305 m) haul
300 ft (90 n) haul, dozer and truck $/m3


300 ft (90 m) haul, dozer and truck $/m3

Test strata in or below landfill, and $/m
Co apply chemical injection, 4 in.
(0.03 m) diameter holes
to blower
to blower
Includes exploratory holes, surveying, $/site
mobilization. drilling addition, pump
test, and report



Source
Means 1980

Means 1980
Means 1980
Means 1980
Means 1980
Means 1980

Means 1980

Dodge 1980

Dodge 1980

Means 1980


Means 1980

Means 1980



rey
SCS 1980


Means 1980
Means 1980
Source
Cost
34.1

27.4
2. 78
18.3
22.3
400
2.65

1.60

0.22

0.76

0.37


1.35

19.7


1 040

5,500


2 .48
7 .20
262

Low
21.5
t
21.1
1 . 75
11.6
15.6
280
1.70

1.20

0.14

0.76

0.23


1.35

13.8


550
650

3,850


1 .56
5.54
165

High
44.7

29.0
3 .63
24.1
26.4
470
3.50

1.70

0.29

0.76

0.48


1.35

23.2


1 , 150
1 360

6,520


3.25
7.63
343

Newark
38.9

25.8
3.13
20.9
23.2
420
3.00

1.50

0.25

0.76

0.42


1.35

20.5


1 ,003
1 180

5,720


2.58
7.50
298
Grout curtain
                                      grout bottom seal)
                                      Two grid - pherolic resin (also for
                                      grout bottom seal)
                                                                                                                   (Sheet 2 of 5)
                                                                                                             (continued)

-------
      TABLE C-3 (Continued)
Component
Header pipe, 8"
Header pipe, 8"
Hydroseeding
Hydroseeding
Hydroseeding
Liner
Materials testing
Monitoring

Monitoring
Mulching
Mulching
Mulching
Pipe, PVC
Pipe, PVC
Pipe, PVC
Pipe, PVC
Pipe, PVC
Pipe, PVC
Pipe, PVC
Pipe, PVC
equipment

wells, gas



(elbows), 6"
(elbows), 6"
(elbows) , 8"
(elbows), 8"
(Tees), 6"
(Tees), 6"
(Tees), 8"
(Tees) , 8"
Subcomponent
Materials
Installation
Labor
Materials
Equipment
Labor Materials
Mater lals/installat:
Materials/installat:
Equipment
Materials
Installation
Labor
Materials
Equipment
Materials
Installation
Materials
Installation
Materials
Installation
Materials
Installation
Definition
PVC Schedule 40
PVC Schedule 40
Includes seed and soil supplements
Includes seed and soil supplements
Includes seed and soil supplements
30 mil, bracketed with heavyweight
Ion For costing, see "Exploratory Boring"

Gas detection nstrunentat on to
Model S3 Gascope)
0.5" (1.3 cm), 12 ft (3.6 m) deep,
for landfill gas monitoring
0.5" (1.3 cm), 12 ft (3.6 m) deep,
for landfill gas monitoring
Hay mulching
Hay mulching
Hay mulching
90" fitting
90° fitting
90° fitting
90° fitting
T-fittirps for gas wells
T-fittings for gas wells
T-fittings for gas wells
T-fittings for gas wells
Metric
Units
$/n
*/m
$/ha
$/ha
$/ha
$/.2
$/each
f/each
S/»
l/m
$/ha
S/ha
«/ha
I/each
$/each
*/each
»/each
I/each
I/each
•/each
*/each
*/m
Source
Means 1980
Means 1980
Dodge 1980
Dodge 1980
Dodge 1980
Dupont 1980
H&A Cons. 1980
SCS 1980
Means 1980
Means
Dodge
Dodge
Dodge
Means
Means
Means
Means
Means
Means
Means
Means
Means
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
Source
Cost
27.4
34.1
171
877
124
6.22
480
500
1.34
8.82
85.2
210
57.3
27.0
28.0
52.0
39.0
37.0
46.0
75.0
59.0
29.20
Low
21.1
21.5
108
675
124
4.35
335
500
1.03
5.55
53.7
162
57.3
20.8
17.6
40.0
24.6
28.5
29.0
57.8
37.2
22.6
29.0
44.7
224
929
124
7.37
570
500
1.42
11.5
111
223
57.3
28.6
36.7
55.1
51.1
39.2
60.3
79.5
77.3
30.9
Newark
25.8
38.9
195
824
124
6.47
500
500
1.26
10.
97.
197
57,
25,
31,
48.
44,
34.
52.
.0
.1

.3
.4
,9
,9
(j
8
4
70.5
67.
27.
,3
6
(includes $4.92/m for perforations)
                                                                     (Sheet 3 of 5)
                                                             (continued)

-------
TABLE C-3  (Continued)
Component
Pipe, PVC, laterals, 8"
Pipe, PVC, laterals, 12"
Pipe, PVC, laterals, 12"
Pipe, PVC, risers, 4"
Pipe, PVC, risers, 4"
Pipe, PVC, risers 6"
Pipe, PVC, risers 6"
Pump, centrifugal
Pump, submersible
Pump, submersible
Recharge trench
Sand
Sheet piling
Sheet piling


P
concrete
Surface seal, bituminous
concrete
Surface seal, clay cap
Surface seal, clay cap
Surface seal, fly ash
cap
Subcomponent
Installation
Materials
Installation
Materials
Installation
Materials
Installation
Equipment /installation
Labor
Materials
Materials/installation
Materials/installation
Materials
Installation




Material
Materials/installation
Materials/installation
Metric
Definition Units
For gas extraction wells, Schedule 40 $/m
(includes $4.92/m for perforations)
For gas extraction wells, Schedule 40 $/m
For gas extraction wells, Schedule 40 */m
g
3/4 HP pump $/each
1 HP - 4", submersible */each
1 HP - 4" submersible $/each
Excavation of trench $/m
For well point casing backfill $/bag
Steel sheet, PMA-22 (22 Ibs/ft2) J/tonne
Install steel sheet, PMA-22 $/tonne
(22 Ibs/ft")
slurry
3
3" (0.08 ») thick cap $/n>2
3" (0.08 m) thick cap $/n>?
T
(46-cm) soil cover
(46-cm) soil cover
12" (30-cm) fly ash, includes 18" S/m
(46-cm) soil cover
Source
Means
Means
Means
Means
Means
Means
Means
Means
Means
Means
Means
Means
Means
Means
Means
Means
Means
Means
Means
Martin
Martin
Martin
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1980
1978
1978
1978
Source
Cost
9.65
41.0
15.4
9.15
22.0
16.4
25.7
1,600
344
424
1.60
5.80
507
100
46.0
0.21
0.51
1.05
3.00
4.82
6.18
4.65
Low
6.08
31.6
11.9
7.05
13.9
12.7
16.2
1,600
220
330
1.12
4.06
390
63
32.2
0.13
0.51
0.66
2.31
3.50
4.51
3.40
12.6
43.7
16.4
9.70
28.8
17.4
33.7
1,600
450
450
i.90
6.87
537
131
54.5
0.25
0.51
1.37
3.18
6.41
8.22
6.18
Newark
11.0
38.6
14.5
8.60
25.1
15.4
30.0
1,600
390
400
1.66
6.03
477
114
47.8
0.22
0.51
1.20
2.82
5.49
7.05
5.30
                                                       (Sheet 4 of 5)
                                                  (continued)

-------
TABLE  C-3 (Concluded)

Component
Surface seal, fly ash
cap
Surface seal, liw-
stablllted cap
Surface seal, FVC
membrane cap
Surface seal , soil-
cement cap
Surveying

Tipping fees
Transportation

Transportation
O
1
CD Treatment system

Trench excavation
Trench excavation
Well points, 2.5"
(6.4 cm) dla
Wellpoint fittings

Subcomponent
Materials/installation

Materials/installation

Materials/installation

Materials/installation

Labor

Unit costs
Labor /equipment

Labor /equipment


Unit costs

Labor
Equipment
Materials/installation

Materials/ installation

Definition
24" (60-co) fly ash cap, Includes 18"
(46-cm) soil cover
5" (13-cm) lime-stabilized cap,
includes 18" (46-cm) soil cover
30-mil PVC membrane cap, Includes
18" (46-cm) soil cover
5" (13-cm) soil-cement cap,
Includes 18" (46-cm) soil cover
Labor cost/day, establish surface
topographic profile
Dumping and grading wastes at new site
30- ton dump truck/driver, based on
trip Included
15-ton dump truck/driver, based on
one-way hauling distance, return
trip Included
Typical costs - interpolated 6 0.12
HGD (440,000 1/d)
One equipment operator/one laborer
Tractor or hydraulic backhoe to
PVC, 25 feet (7.6 m)

Fittings and accessories
Metric
Units Source
$/m Martin 1978

$/m2 Martin 1978

$/m2 Martin 1978

$/m2 Martin 1978

(/day SCS 1980

$/tonne SCS 1979
$/tonne-km SCS 1981

$/tonne-km SCS 1981


$/each Dodge 1980

J/m3 Means 1980
$/a Means 1980
$/m Davis 1980

I/well Davis 1980
Source
Cost
6.27

6.05

10.8

6.05

220

110
0.096

0.110


580K

0.22
1.16
59.3

12.0

Low Hlfi;h Newark
4.49 8.36 7.15

5.24 8.04 6.90

9.7 14.4 12.3

5.24 8.04 6.90

150 260 230

110 110 110
0.060 0.128 0.109

0.069 0.145 0.125


406K 687K 603K

0.17 0.35 0.31
1.16 1.16 1.16
41.5 70.3 61.7

8.40 14.2 12.:
                                                    (Sheet 5 of 5)

-------
                 TABLE C-4




LANDFILL O&M COST COMPONENTS - METRIC UNITS


o
1
-J

Component
Chemicals
Electricity
Grubbing
Maintenance/repair ,
diversion ditch
Monitoring
Monitoring (analysis)
Monitoring (sampling)
Grass mowing
Operating cost
Operating cost
Refertllizatlon
Hater
Subcomponent
Materials
Power costs
Labor /equipment
Installation
Labor
Laboratory costs
Labor
Labor /materials
Labor
Labor
Labor /materials
Materials
Definition
Wastewater/leachate treatment plant
chemicals
Assume annual grubbing (clearing) of
brush
Assume diversion ditch needs rebuild-

For ground water/leachate monitoring
from monitoring wells
from monitoring wells
Use 58" power ride mower, one operator
personnel
For gas collection system operating
personnel
Assume refertllization once per year
Metric
Units
$/t/day
(influent)
$/kwh
$/»2
?/m3
$/hr
Vsample
$/hr
*/ha
$/hr
$/hr
$/ha
S/kl
So
SCS
SCS
Dodg
SCS
SCS
SCS
urce
1980
1980
e 1980
s 1980
1980
1980
1980
Dodge 1980
SCS 1980
SCS
1980
Dodge 1980
SCS 1980
Source
Cost
0.025
0.05
0.19
2.75
12.5
330
12.5
93.9
10
15
341
0.92
Low
0
0
0
1.
7,
330
7,
66.
6.
9.
247
0.
.025
.05
.12
.73
,88
.88
.7
.30
.45
,92
High
0.025
0.05
0.25
3.60
16.6
330
16.6
111
13.10
19.95
396
0.92
Newark
0.025
0.05
0.22
3.14
14.3
330
14.3
98.9
11.39
17.10
346
0.92

-------
                                                                                               TABLE  C-5

                                                 SURFACE  IMPOUNDMENT  CAPITAL  COST  COMPONENTS   -  METRIC  UNI™
                        Component
 I
ro
Area preparation


Area preparation


Bentonite, delivered


Cement pipe, 6"

Ceawnt pipe, 6"

Discharge trench

Dlacharge trench

Diversion ditch,
Construction

Drilled holes, 6"

Drill rig


Excavation

Excavation

Excavating/grading,
soil

Excavating/grading,
soil

Geotechnical investig-
ation
                 Geotechnical  investig-
                 tlon
                 Grout curtain
                                                Subcomponent
                                                                                Definition
                                                                 Metric
                        	      Units

Labor                   For area preparation, rake and clean      $/m
                        up, average

Equipment                For area preparation, rake and clean      $/n
                        up, average

Materials/shipping       Shipment of bentonite by rail near  job    $/tonne
                        site,  includes materials and delivery

Materials                Class  4000, perforated, asbestos         $/m

Installation             Class  4000, perforated, asbestos         $/m

Labor                   Including backfill  3 ft (1 m) deep        »/m3

Equipment                Including backfill  3 ft (1 m) deep        $/m

Installation             Construction and maintenance/repair      $/n


Materials/installation    Drilled and cased with pipe              $/m

Rental (Equipment/       Crew and light-duty rig                  J/day
labor)

Labor                   One equipment operator                   $/m

Equipment                Front  end loader                        $/•

Labor                   Common borrow (earth), 1000 ft           $/m
                        (305 m) haul

Equipment                Common borrow (earth), 1000 ft           $/ro
                        (305 m) haul

Unit costs               Includes surveying, test borings,        $/each
                        equipment, mobilization, monitoring
                        wells, pump tests,  report

Unit costs               Slurry wall testing                     S/each


Labor/installation       3/4" screened gravel, one dozer          $/m
                        operator, one truck driver

Materials                3/4" screened gravel, one dozer          $/m
                        operator, one truck driver
                                                                                                                                           Source
                                                                                                                                           Cost
                                            Labor
                                                                    Chemical grout, phenolic  resin,
                                                                    2-grid
Dodge 1980


Dodge 1980


Burlington
Northern  1980

Means 1980

Means 1980

Means 1980

Means 1980

Means 1980


Means 1980

Means 1980


Means 1980

Means 1980

Dodge 1980


Dodge 3980


SCS 1980



SCS 1980


Means 1980


Means 1980


Means 1980
  8.00

  3.10

  1.97

  1.57

  2.78


 22.3

400


  0.16

  0.65

  0.22


  0.76
                                                                                                                                         2,000
    0.047


    0.022


   66.4


    6.16

    1.95

    1.24

    1.57

    1.75


   15.6

  280


    0.10

    0.65

    0.14


    0.76


9,500



1,260


    1.56


    5.54


  165
    0.096


    0.022


   177


    8.48

    4.06

    2.58

    1.57

    3.63


    26.4

   470


    0.21

    0.65

    0.29


    0.76


19,500
Newark
  0.084


  0.022


166


  7.52

  3.53

  2.23

  1.57

  3.13


 23.2

420


  0.18

  0.65

  0.25


  0.76
                                                                                                                                                                              16,900
                                                                                                                                                  2,620       2,260


                                                                                                                                                      3.25         2.58


                                                                                                                                                      7.63         7.50


                                                                                                                                                    343         298



                                                                                                                                                           (Sheet 1 of 3)
                                                                                                                                                                                       (continued)

-------
         TABLE C-5  (Continued)
















o
I
_J
00










Component
Grout curtain
Reader and discharge
Pipe. 8"
Header and discharge
pipe, 8"
Hydroseeding
Hydroseeding
Hydroseeding
Mulching
Mulching
Mulching
Pump, centrifugal
Pump, submersible
Pimp, submersible

Sheet piling


Sheet piling
Slurry mil.
Installation
Slurry wall teatlng

Soil compacting
Soil compacting
Sump
Sump

Subcomponent
Materials
Materials

Installation

Labor
Materials
Equipment
Labor
Materials
Equipment
Equipment /installation
Labor/ installation
Materials

Labor /equipment/
Installation

Materials
Installation

Unit cost

Labor
Equipment
Labor /equipment
Materials
Metric
Definition Units
Chemical grout, phenolic lesin, 2-grid $/m
PVC class 150 pipe, laid in trench |/m

PVC class 150 pipe, laid in trench $/m

Seed and soil supplements/amendments J/m
Seed and soil supplements/amendments $/m
Hydroseeding $/m
Mulching hay $/m
Mulching hay $/n
Mulching hay $/m2
3/4 HP pump $/each
1 HP, 4", including wiring S/each
1 HP, 4", Including wiring t/each

PMA-22 steel sheet piling (22 lbs/ft2) t/tonne


PMA-22 steel sheet piling (22 lbs/ft2) S/tonne
Install slurry compound in excavated $/n
trench
See "Geotechnical Investigation,
Slurry wall testing"
Uith sheepsfoot roller $/«
tflth sheepsfoot roller $/m
16 ft (5 *) deep x 8" (20 cm) i/each
16 ft (5 m) deep X 8" (20 en) I/each


Source
Means
Means

Means

Dodge
Dodge
Dodge
DodRe
Dodge
Dodge
Means
Means
Means

Means


Means
Means



Means
Means
Means
Means
1980
1980

1980

1980
1980
1980
1980
1980
1980
1980
1980
1980

1980


1980
1980



1980
1980
1980
1980
Source
Cost
56.2
24.2

9.61

0.0171
0.0877
0.0124
0.0085
0.0210
0.0057
1.600
344
424

100


507
45.9



0.63
0.86
820
750

Low
43.3
18.6

6.05

0.0108
0.0675
0.0124
0.0054
0.0162
0.0057
1,600
220
330

63


390
32.2



0.40
0.86
516
577



High Newark
59.6
25.6

12.6

0.0224
0.0929
0.0124
0.0112
0.0223
0.0057
1,600
450
450

131


537
54.5



0.83
0.86
1,074
795
52
22

10

0.
0.
0
0
0.
0
1,600
390
400

114


476
47.



0
0.
926
705
.8
.7

.9

.0195
.0824
.0124
.0097
.0197
.0057








.8



.71
.86


thick concrete, cast In place
                                                                   (Sheet 2 of 3)
                                                               (continued)

-------
TABLE  C-5 (Concluded)





o
1




Component
Surface seal, bituminous
concrete

concrete


Surface seal, fly ash
cap
Surface seal, fly ash
cap
Surface seal, lime-
stabilized cap
membrane cap
Surface seal, soil-
cement cap
Surveying
Tipping fee

Treatment plant
Trench excavation
Trench excavation
Well fittings, 8"
Well fittings, 8"
Well points, 2.5"
Wellpolnt fittings
Subcomponent
Labor /equipment
Materials


Materials /ins tall at ion
Materials/installation
Materials/installation
Materials/installation
Materials/installation
Labor
Unit costs
Labor /equipment
Labor /equipment
Unit costs
Labor
Equipment
Materials
Installation
Materials/installation
Unit costs
Definition
3" (0.08 m) thick cap
3" (0.08 m) thick cap
(46-cm) soil cover
(46-cm) soil cover
12" (30-cm) fly ash cap, includes 18"
(46-cm) sol 1 cover
24" (60-cm) flv ash cap, includes 18"
(46-cm) soil cover
5" (13-cm) limp-stabilized cap,
30-mil PVC membrane cap, includes
IB" (46-cm) soil cover
5" (13-cm) soil-cement cap, includes
18" (46-cm) soil cover
Labor costs/day
Fee paid at secure landfill
30-ton dump truck/driver, based on
one-wav haulinp distance, return
trip included
one-way hauling distance, return
trip included
1980, with SCS estimate
16 ft (5 m) deep x 3 ft (1 m) wide,
16 ft (5 m) deep x 3 ft (1 m) wide,
PVC
PVC
16 ft (4.9 m) long

Metric
Units
$/m2
*/m2
$/m2
$/m2
i/m2
$/m2
$/m2
$/day
$/tonne
$/tonne-km
$/tonne-kra
$/l/day
t/n3
$/well
$/well
J/n
$/weJl
Source
Means 1980
Means 1980
Martin 1978
Martin 1978
Martin 1978
Martin 1978
Martin 1978
Martin 1978
Martin 1978
Means 1980
SCS 1979
SCS 1981
SCS 1981
Dodge 1980
Means 1980
Means 1980
Means 1980
Means 1980
Dodge 1980
Dodge 1980
Source
Cost
1.05
3.00
4.82
6.18
4.60
6.28
6.05
10.8
6.05
220
110
0.096
0.110
0.89
0.22
1.16
127
98
59.3
12.0
Low
0.72
2.31
3.50
4.51
3.40
4.49
5.24
9.72
5.24
150
110
0.060
0.069
0.70
0.17
1.16
97.8
61.4
40
8.40
1.24
3.18
6.41
8.22
6.18
8.36
8.04
14.4
8.04
260
110
0.128
0.145
1.18
0.35
1.16
134.6
128.4
70
14.2

1.09
2.82
5.49
7.05
5.24
7.15
6.90
12.3
6.90
230
110
0.109
0.125
1.04
0.31
1.16
119.4
110.7
62
12.5
                                                     (Sheet 3 of 3)

-------
                       TABLE C-6



SURFACE IMPOUNDMENT O&M COST COMPONENTS - METRIC UNITS
Component
Chemicals

Electricity


Refertlllzlng
Grass mowing

Grubbing

Maintenance/repair ,
diversion ditch
Monitoring (sampling)

Operator personnel
O
1 '
Subcomponent
Materials

Power costs


Labor /materials
Labor /equipment

Labor/equipment

Installation

Labor

Labor


Metric
Definition Units
Uastewater/leachate treatment plant I/I/day
chemicals (Influent)
For water treatment plant or extrac- $/kwh
tlon, injection, and gas control
wells/pumps
Assume fertilizing once/year $/m
Assume grass mowing 6 times/year, $/m
minimum $10 per visit
Assume annual grubbing (clearing) of $/m
brush
Assume twice annual ditch repair t/m

from monitoring wells
For ground water/leachate monitoring $/hr
from monitoring wells
For operation of water treatment plant $/hr
and sampling for monitoring

Source
SCS 1980

SCS 1980


Dodge 1980
Dodge 1980

Dodge 1980

Means 1980
SCS 1980
SCS 1980

SCS 1980


Source
Cost
0.025

0.05


0.0060
0.0015

-0.19

2.78
330
12.5

12.6


Low High
0.025 0.025

0.05 0.05


0.0046 0.0064
0.00097 0.002

0.12 0.25

1.75 3.63
330 330
7.88 16.6

7.92 16.3


Newark
0,

0


0
0.

.025

.05


.0056
.0017

0.22

3
330
14

14



.16

.2

.3



-------

-------
                                  APPENDIX 0
            SYMBOLS, ABBREVIATIONS, AND ACRONYMS; METRIC CONVERSION
a (alpha)
AASHO
AASHTO

ADS
AET
ARS
ASCE
ASTM
b
B_
CBR
CERCLA

cc
cfs
CH

CL
area;
activity;
slope of saturation vapor pressure curve;
acre
vegetation parameter
slope angle
American Association of State Highway Officials
American Association of State Highway and
Transportation Officials
agricultural drainage standard
actual evapotranspiration
Agricultural Research Center
American Society of Civil Engineers
American Society for Testing and Materials
bottom channel width
channel surface width
clay (in the Unified soil classification system);
percent of clay-sized material;
runoff coefficient;
Centigrade (Celsius)
California Bearing Ratio
Comprehensive Environmental Response, Compensation,
and Liability Act (of 1980)
cubic centimeter
cubic feet per second
a soil group in the Unified Soil Classification
System
a soil group in the Unified Soil Classification
System
                                      D-l

-------
cm
CN
CPE
CRREL
CSA
CST
Cu
Cu
CU
c.y.
0
D10, D5Q, etc.
DA
Dd
6 (delta)

6m
 t
dia.
E
e
 max
 min
centimeter
curve number
chlorinated polyethylene
Cold Regions Research and Engineering Laboratory
Canadian Standards Association
change in soil moisture storage
Coefficient of Uniformity
see  Cu
cubic
cubic yard
depth;
diameter
diameter;
depth;
angle of repose;
thickness of drainage blanket
diameter of 10-pct-finer, 50-pct-finer,
etc., soil particle
Department of the Army
relative density
correction for consistent or systematic error of
measurement process
correction for systematic error due to material
composition
correction for systematic error due to placement
process
correction for systematic error due to material
quality
correction for systematic error due to testing
process
diameter
maximum allowable error
void ratio;
rate at which water impinges on drainage layer;
base of natural logarithms;
allowable sampling error
maximum void ratio
minimum void ratio
                                      D-2

-------
 E.O.S.
 EPA
 EPDM
 e  (epsilon)
 F

 f
 FA
 Fb
 f
 Fed.
ft
G

g
gal
Y (gamma)
vw
GC

GI
GM

GP

Gs
GW
 equivalent  opening  size
 Environmental  Protection Agency
 ethylene propylene  diene monomer
 correction  for random  deviation about  the  average
 Fahrenheit;
 total water infiltrated
 infiltration capacity
 fly ash
 bend factor
 equilibrium infiltration capacity
 Federal
 initial infiltration capacity
 infiltration capacity  one hour after start of
 excess precipitation
 foot, feet
 foot, feet
 specific gravity;
 gravel (in  the Unified soil classification system)
 acceleration of gravity;
 gram(s)
 gal Ion
 unit weight
 dry unit weight, dry density
 unit weight of solids
 total unit weight
 unit weight of water
 a soil  group in the Unified Soil  Classification
 System
 vegetation growth index
 a soil  group in the Unified Soil  Classification
 System
 a soil  group in the Unified Soil  Classification
System
 specific gravity of solids
a soil  group in the Unified Soil  Classification
System
                                      D-3

-------
H                           height;
                            high (in the Unified Soil Classification System);
                            horizontal;
                            net daily solar radiation
h                           height;
                            head
HCB                         hexachlorobenzene
HOPE                        high-density polyethylene
HELP                        Hydrologic  Evaluation of Landfill  Performance
h                           height to which water will rise in blanket layer
 \l\Qf\
HP                          horsepower
hr                          hour
HWS                         hazardous waste site
I                           rainfall intensity;
                            infiltration
i                           hydraulic gradient
I                           initial abstraction
 a
in.                         inch,  inches
"                           inch,  inches
K                           hydraulic conductivity;
                            Kelvin (temperature  scale)
k                           coefficient  of permeability;
                            decay  constant in exponential  equation
kN                          kilonewton
K                           saturated hydraulic  conductivity
k                           saturated permeability of drainage blanket
 s
K                           unsaturated  hydraulic conductivity
L                           distance or  length;
                            low (in the  Unified  Soil Classification System);
                            twice  the distance between subdrains;
                            albedo
LAI                         leaf area index
1                           length
Ib.                         pound
LCFA                        lime,  cement, fly ash, aggregate
l.f.                        linear foot
                                      D-4

-------
 LFA                          lime,  fly ash, aggregate
 LL                           liquid  limit
 M                            silt  (in the Unified Soil Classification System)
 m                            meter
 2
 m                            square  meter
 max.                         maximum
 MH                           a  soil  group in the Unified Soil Classification
                             System
 MIL                          military
 mil                          (see glossary)
 min.                         minimum;
                             minute
 ML                           a  soil  group in the Unified Soil Classification
                             System
 mm                           mi 11imeter(s)
 MPa                          megapascal
 mph                          miles per hour
 M (mu)                       kinematic viscosity;
                             expected or mean value;
                                            - fi
                             micro-  (=  x 10  )
 u                            expected value or average of many observations
 p                           recorded for a process
 u                            true or accepted reference level of a property
                             of material  to be measured
 n                            number of units in a sample;
                             porosity;
                             roughness coefficient (Manning's equation)
 NCC                          National Climatic Center
 NCR                          National Contingency Plan
 n                            effective porosity
 NR                           not recommended
 N.T.S.                       not to scale
0                            organic (in  the Unified Soil Classification System)
OH                          a soil group in the Unified Soil Classification
                             System
OL                          a soil group in the Unified Soil Classification
                             System

                                      D-5

-------
P                           poorly graded (in the Unified Soil Classification
                            System);
                            wetted perimeter;
                            precipitation;
                            a numerical exponent
P.,-                         total 5-day antecedent rainfall
PCA                         Portland Cement Association
pcf                         pounds per cubic foot
pet                         percent
PE                          polyethylene
PERC                        percolation
PET                         potential evapotranspiration
pH                          (see glossary)
 (phi)                     diameter;
                            angle of internal friction
PI                          plasticity index
PL                          plastic limit
pis                         pure live seed
PSD                         pipe slope drain
psf                         pounds per square foot
psi                         pounds per square inch
Pt                          peat (in the Unified Soil Classification System)
PVA                         polyvinyl acetate
PVC                         polyvinyl chloride
Q                           volumetric flow rate
R                           hydraulic radius;
                            runoff;
                            incident daily solar radiation
r                           radius
RCRA                        Resource Conservation and Recovery Act (of 1976)
p (rho)                     density
RO                          surface runoff
R                           radius of channel bend
                                      D-6

-------
 S                            degree of saturation;
                             sand (in  the Unified Soil  Classification System);
                             slope;
                             potential  retention;
                             available soil  moisture  storage capacity;
                             capillary suction
 s                            second
 S.                           channel bottom  slope
 SC                           a  soil group in the  Unified  Soil  Classification
                             System
 SCS                          Soil  Conservation  Service
 sec                          second
 SF                           safety factor
 s.f.                         square foot
 a (sigma)                    standard  deviation
 OQ                           total  standard  deviation
 a                            quality standard deviation
 o~t                           testing standard deviation

 2
 cr                            variance
o~m                          variance due to material composition

 2
o                           overall variance

 2
a                           variance due to placement process

 2
a                           variance due to material quality

 2
a.                           variance due to testing process

a                           known or estimated true value of universe or lot
                            standard deviation
SL                          shrinkage limit
SM                          a soil group in the Unified Soil Classification
                            System;
                            snowmelt
S                           threshold degree of saturation
                                      D-7

-------
SP                          a soil group in the Unified Soil Classification
                            System
Spec.                        specification
sq.                          square
S                           actual degree of saturation
 5
STD                         standard
SW                          a soil group in the Unified Soil Classification
                            System
SWMP                        Surface Water Management Program or Plan
s.y.                        square yard
T                           temperature;
                            top channel width
t                           time;
                            probability factor, from Student-t tables
t                           time of concentration
T                           total soil porosity
t  .                        time of saturation
 sat
tsf                         tons per square foot
USAE                        U.  S. Army Engineer
USER                        U.  S. Bureau of Reclamation
USCE                        U.  S. Army Corps of Engineers
USCS                        Unified Soil Classification System
USDA                        U.  S. Department of Agriculture;
                            U.  S. Department of the Army
USGS                        U.  S. Geological Survey
V                           volume;
                            velocity;
                            vertical
V                           volume of gas
 9
Vol                         volume
V                           volume of solids
V                           volume of voids
 v
Vw                          volume of water
V                          coefficient of variation
                                      D-8

-------
W                           weight;
                            well-graded (in the Unified Soil Classification
                            System)
w                           water content;
                            width
w                           effective water content
WES                         Waterways Experiment Station
W,                          liquid limit
W                           plastic limit
W                           weight of solids;
                            shrinkage limit
wt                          weight
W                           weight of water
 W
X                           numerical value of a measurement
X                           expected (mean) value of characteristic being
                            measured
y                           channel depth
yd                          yard
  2
yd                          square yard(s)
yd                          cubic yard(s)
Z                           reciprocal  of tangent of slope angle;  number of
                            horizontal  units for a vertical  rise of one.
                                      D-9

-------
                                   TABLE D-l

                            METRIC CONVERSION TABLE
       Multiply
acres

atmospheres

cubic feet per second

cubic yards

Fahrenheit degrees

feet

gallons (U. S. liquid)

inches

kips (force)

miles (U.  S.  statute)

pounds (force)

pounds (force) per
  square inch

pounds (mass)

tons (short,  mass)

tons (short,  mass)
     By
         To Obtain
   0.4046856

 101.325

   0.02831685

   0.7645549

   5/9

   0.3048

   3.785412

   0.0254

   4.448222

   1.609347

   4.448222

6894.757


   0.4535924

 907.1847

   1.102
hectares

kilopascals

cubic meters per second

cubic meters

Celsius degrees or Kelvins'

meters

liters

meters

kilonewtons

kilometers

newtons

pascals


kilograms

kilograms

metric tons (tonnes)
 To obtain Celsius (C) temperature readings from Fahrenheit (F) readings,
 use the following formula:   C = (5/9) (F - 32).   To obtain Kelvin (K)
 readings, use:   K = (5/9) (F - 32) + 273.15.
                                     D-10

-------
                                  APPENDIX E

                                   GLOSSARY
      This glossary is intended to define terms in this Handbook as well as
some terms that may be encountered in researching subjects herein.   Chief
sources for this glossary were the glossaries presented by Lee et al.  (1984),
Haxo et al.  (1980), Hi If (1974c), and Johnson (1981), and definitions in
Webster's Third New International Dictionary (G. & C. Merriam Co.,  1981).  In
some cases original definitions were prepared from other sources by the pre-
parers of this Handbook.   Where terms are defined by cross-reference, the term
specifically defined is not necessarily to be preferred.
                                     E-l

-------
ABSORPTION:   A taking up by capillary,  osmotic,  chemical  or solvent action;
distinguished from adsorption.

ACID SOIL:   A soil with a preponderance of hydrogen ions  and probably of
aluminum in proportion to hydroxyl ions.   Specifically, soil with a pH value
less than 7.0.  For most practical purposes, a soil with  a pH value less than
6.6.  The pH values obtained vary greatly with the method used; consequently,
there is no unanimous agreement on what constitutes an acid soil.  The term is
usually applied to the surface layer or to the root zone  unless specified
otherwise.

ACTIVITY:  In clay terminology, a property of clay minerals related to the
plasticity of the soils in which they occur.

ADSORPTION:   A taking up by physical (physical adsorption) or chemical (chemi-
sorption) forces of the molecules (or ions) of gases, dissolved substances, or
liquids by the surfaces of solids or liquids with which they are in contact;
distinguished from absorption.

AEOLIAN DEPOSITS:  Wind-deposited material such as dune sands and loess
deposits.

AERATION, SOIL:  The process by which air in the soil is  replenished by air
from the atmosphere.  In a well-aerated soil, the air in  the soil is similar
in composition to the atmosphere above the soil.  Poorly aerated soils usually
contain a much higher percentage of carbon dioxide and a correspondingly lower
percentage of oxygen.  The rate of aeration depends largely on the volume and
continuity of pores in the soil.

AGGREGATE:  A granular material of mineral composition such as sand, gravel,
shell, slag, or crushed stone, used with a cementing medium to form mortars or
concrete, or alone as in roadway base courses, railroad ballast, etc.

AIR DRY:  The state of dryness (of a soil) at equilibrium with the moisture
content  in the surrounding atmosphere.  The actual moisture content will
depend on the relative humidity and the temperature of the  surrounding
atmosphere.

AIR LANCE:  A device  used to test,  in the field, the  integrity of field seams
in  plastic sheeting.  It consists of a wand or tube through which compressed
air is blown.

ALKALINE SOIL:   A  soil that has a pH value  greater than 7.0, particularly
above 7.3, throughout most or  all of the  root zone, although the term  is
commonly applied  to  only the surface layer  or horizon  of  a  soil.

ALLOYS,  POLYMERIC:   A blend of two  or more  polymers,  e.g.,  a rubber  and a
plastic, to  improve  a given property, e.g.,  impact strength.

ALLUVIUM:  Soil  the  constituents  of which  have  been  transported  in  suspension
by  flowing water and  subsequently deposited by  sedimentation.


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AMENDMENT:  Any material, such as lime, gypsum, sawdust, or synthetic condi-
tioners, that is worked into the soil to make it more productive.  The term is
used most commonly for added materials other than fertilizer.

AMPHOTERIC:   Having the property of reacting as either an acid or a base.
Many oxides and salts have this ability (aluminum hydroxide, for example).

ANCHOR TRENCH:  A long narrow ditch on which the edges of a plastic sheet are
buried to hold it in place or to anchor the sheet.

ANGLE OF INTERNAL FRICTION:   Angle between the abscissa and the tangent of the
curve representing the relationship of shear resistance to normal stress
acting within a soil.

ANGLE OF REPOSE:  Angle between the horizontal and the maximum slope that a
soil assumes through natural processes.  For dry granular soils the effect of
the height of slope is negligible; for cohesive soils the effect of height of
slope is so great that the angle of repose is meaningless.

ANION EXCHANGE CAPACITY:   The sum total of exchangeable anions that a soil can
absorb.   Expressed as milliequivalents per 100 gram of soil (or other absorbing
materials such as clay).

ANISOTROPIC MASS:  A mass having different properties in different directions
at any given point.

ANNUAL PLANT:  A plant that completes its life cycle in one year or less.

AQUIFER:  A water-bearing formation that yields economically significant quan-
tities of ground water.

ARTESIAN:  An adjective referring to ground water confined under hydrostatic
pressure.

ASH (FIXED SOLIDS):  The incombustible material that remains after a fuel or
solid waste has been-burned.

ASPHALT:  A dark-brown to black semisolid cementitious materia-l consisting
principally of bitumens which gradually liquefy when heated and which occur in
nature as such or are obtained as residue in the refining of petroleum.

ASPHALT CEMENT:   A fluxed or unfluxed asphalt specially prepared as to quality
and consistency for direct use in the manufacture of bituminous pavements and
having specified penetration consistency.

ASPHALT MEMBRANE:  A relatively thin layer of asphalt formed by spraying a
high viscosity,  high softening point asphalt cement in two or more applications
over the surface to be covered.   It is normally 1/4-in.  thick and buried to
protect it from weathering and mechanical  damage.
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ATTERBERG LIMITS:  Moisture-content values which are measured for soil materi-
als passing a no. 40 sieve and which define soil plasticity properties.  The
Atterberg Limits are the Liquid Limit, Plastic Limit, and Shrinkage Limit,
q.q.v.

AVAILABLE NUTRIENT:   That portion of any element or compound in the soil that
readily can be absorbed and assimilated by growing plants.   Not to be confused
with exchangeable.

AVAILABLE WATER:  The portion of water in a soil that can be absorbed by plant
roots; usually that water held in the soil against a soil water pressure of up
to approximately 15 bars.  See Figure 4-5.

BAND SEEDING:   Seeding of grasses and legumes in a row one to two inches
directly above a band of fertilizer.

BASE COURSE (BASE):   In highway construction, a layer of specified or selected
material of planned thickness constructed on the subgrade or subbase for the
purpose of serving one or more functions such as distributing load, providing
drainage, minimizing frost action, etc.

BASE EXCHANGE:  The physicochemical process whereby one species of ions ad-
sorbed on soil particles is replaced by another species.

BENTONITE:   A rock or natural deposit composed largely of montmorillonite.
Because of its swelling and slaking properties it is used in oil-well  drilling
muds and sealing applications such as slurry trenches.

BERM:   A level area which breaks the continuity of a slope, or which forms the
shoulder of a road.   Also loosely used to mean an embankment with a level top.

BINDER (SOIL):  Portion of soil passing No.  40 United States standard sieve.

BIODEGRADABLE:  Susceptible to decomposition as a result of attack by micro-
organisms - said of organic materials.

BITUMEN:  A class of black or dark-colored (solid, semisolid, or viscous)
cementitious substances, natural or manufactured, composed principally of
relatively high-molecular-weight hydrocarbons.  Asphalts, tars, pitches, and
asphaltites are typical examples of bitumen.

BLOCKING:  Unintentional adhesion usually occurring during storage or shipping
between plastic films or between a film and another surface.

BLOWN ASPHALT (AIR-BLOWN ASPHALT):  Asphalt produced in part by blowing air
through it at a high temperature.  If a catalyst, e.g., ferric chloride or
phosphorus pentoxide, is used in the air-blowing operation, the product is
known as catalytically-blown asphalt.

BODIED SOLVENT ADHESIVE:  An adhesive consisting of a solution of the liner
compound used in the seaming of liner membranes.


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BOOT:  A bellows-type covering to exclude dust, dirt, moisture, etc., from a
flexible joint.

BOULDER:  A rock fragment, usually rounded by weathering or abrasion, with an
average dimension of 12  inches or more.

BREAKING FACTOR:  Tension at break in  force per unit of width; units, SI:
Newton per meter, customary:  pound per  inch.

BRUSH MATTING:  1.  A matting of branches placed on badly eroded land to
conserve moisture and reduce erosion while trees or other vegetative covers
are being established.   2.  A matting  of mesh wire and brush used to retard
streambank erosion.

BULKING:  The  increase in volume of a  material due to manipulation.  Rock
bulks upon being excavated; damp sand  bulks if loosely deposited, as by dump-
ing, because the "apparent cohesion" prevents movement of the soil particles
to form a reduced volume.

BUNCHGRASS:  A grass that does not have rhizomes or stolons and forms a bunch
or tuft.

BUTT JOINT:  A joint in which the edges of two plates, sheets, etc. , to be
joined are merely abutted together without overlap.

BUTYL RUBBER:   A synthetic rubber based on isobutylene and a minor amount of
isoprene.   It  is vulcanizable and features low permeability to gases and water
vapor and good resistance to aging, chemicals, and weathering.

CALCAREOUS SOIL:  Soil containing sufficient free calcium carbonate or magne-
sium carbonate to effervesce carbon dioxide visibly when treated with cold 0.1
normal hydrochloric acid.

CALIFORNIA BEARING RATIO:  The ratio of (1) the force per unit area required
to penetrate a soil mass with a 3-square-inch circular piston (approximately
2-inch-diameter) at the rate of 0.05 inch per minute to (2) that required for
corresponding penetration of a standard material.

CAPILLARY ACTION (CAPILLARITY):   The rise or movement of water in the inter-
stices of a soil due to capillary forces.

CAPILLARY FRINGE:   The lower subdivision of the zone of aeration,  immediately
above the water table, in which the interstices are filled with water under
pressure less  than that of the atmosphere, being continuous with the water
below the water table but held above it by surface tension.   Its upper boundary
with the intermediate belt is indistinct but is sometimes defined arbitrarily
as the level  at which 50 percent of the interstices are filled with water.

CAPILLARY HEAD:  The potential,  expressed in head of water,  that causes  the
water to flow by capillary action.
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CAPILLARY MIGRATION (CAPILLARY FLOW):   The movement of water by capillary
action.

CAPILLARY PRESSURE:  The difference in pressure across the interface between
two immiscible fluid phases jointly occupying the interstices of a rock.   It
is due to the tension of the interfacial surface, and its value depends on the
curvature of that surface.

CAPILLARY RISE (HEIGHT OF CAPILLARY RISE):  The height above a free water
elevation to which water will rise by capillary action.

CATION EXCHANGE CAPACITY (BASE EXCHANGE CAPACITY):   A measure of the extent to
which the cations in a soil (adsorbed on mineral surfaces; within the crystal
framework of some mineral species; and within certain organic compounds) can
be reversibly replaced by those of salt solutions and acids.  Usually expressed
in meq.  (milliequivalents) per 100 grams of soil.

CELL:  Portion of waste in a landfill  which is isolated horizontally and
vertically from other portions of waste in the landfill  by means of soil
barrier.

CHEMICAL FIXATION:  Treatment process which involves reactions between the
waste and certain chemicals, and which results in solids which encapsulate,
immobilize or otherwise tie up hazardous components in the waste so as to
minimize the leaching of hazardous components and render the waste nonhazardous
or more suitable for disposal.

CHLORINATED POLYETHYLENE (CPE):  Family of polymers produced by chemical
reaction of chlorine on the linear backbone chain of polyethylene.  The re-
sultant rubbery thermoplastic elastomers presently contain 25-45% chlorine by
weight and 0-25% crystallinity.  CPE can be vulcanized but is usually used in
a nonvulcanized form.

CHLOROSULFONATED POLYETHYLENE (CSPE):   Family of polymers that are produced by
polyethylene reacting with chlorine and sulfur dioxide.   Present polymers
contain 25-43% chlorine and 1.0-1.4% sulfur.  They are used in both vulcanized
and nonvulcanized forms.  Most membranes based on CSPE are nonvulcanized.
ASTM designation for this polymer is CSM.

CHUTE:  A high-velocity, open channel for conveying water to a lower level
without erosion.

CLAY (CLAY SOIL):  Fine-grained soil or the fine-grained portion of soil that
can be made to exhibit plasticity (putty-like properties) within a range of
water contents, and which exhibits considerable strength when air-dry.

CLAY MINERALS:  Naturally occurring hydrous aluminosilicate minerals with a
planar or sheetlike crystal structure (known as phyllosilicates), formed in
nature by weathering or hydrothermal action, always very fine-grained, usually
occurring in earthy masses.   Positive identification of clay minerals usually
requires a combination of optical, x-ray, chemical and/or physical tests.


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CLAYPAN:   A dense, compact layer in the subsoil having a much higher clay
content than the overlying material from which it is separated by a sharply
defined boundary; formed by downward movement of clay or by synthesis of clay
in place during soil formation.

CLAY SIZE:   Grain sizer finer than 0.002 mm.  (0.005 mm.  in some cases).   See
discussion in Sec. 3.2.2, and Figure 3-3.

COAL TAR:   Tar produced by the destructive distillation of bituminous coal.

COATED FABRIC:  Fabrics which have been impregnated and/or coated with a
plastic material in the form of a solution, dispersion,  hotmelt, or powder.
The term also applies to materials resulting from the application of a pre-
formed film to a fabric by means of calendering.

COBBLE:  A rock fragment usually rounded or semi rounded with an average dimen-
sion between 3 and 12 inches.

COEFFICIENT OF COMPRESSIBILITY (COEFFICIENT OF COMPRESSION):  The secant
slope, for a given pressure increment, of the pressure/void-ratio curve.

COEFFICIENT OF INTERNAL FRICTION:  The tangent of the angle of internal  fric-
tion (see Internal Friction).

COEFFICIENT OF PERMEABILITY:   The rate of discharge of water under laminar-flow
conditions and at a standard temperature (usually 20°C) through a unit cross-
sectional  area of a porous medium under a unit hydraulic gradient.   Frequently
simply termed "permeability" in soil-mechanics usage.  See "Permeability."

COEFFICIENT OF UNIFORMITY:  The ratio  D60/Di0 ,  where  Dgo  is the particle
diameter corresponding to 60 percent finer on the grain-size curve, and  D10
is the particle diameter corresponding to 10 percent finer on the grain-size
curve.

COHESION:   That part of soil strength that is present independently of any
applied pressures, either mechanical or capillary, and would remain, though
not necessarily permanently, if all applied pressures were removed.   Indicated
by the term  C  in the Coulomb equation:   S = C + a tan <(> .

COHESIONLESS SOIL:  A soil that when unconfined has little or no strength when
air-dried,  and that has little or no cohesion when submerged.

COHESIVE SOIL:  A soil that when unconfined has considerable strength when
air-dried,  and that has significant cohesion when submerged.

COLLOID:   In soil, organic or inorganic matter having very small particle size
and a correspondingly large specific surface.  In general, colloidal particles
are too small to be seen with the ordinary compound microscope, and remain
indefinitely in a suspension rather than settling out.

COMPACTION:   The densification of a soil  by means of mechanical manipulation.


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COMPACTION CURVE (PROCTOR CURVE) (MOISTURE-DENSITY CURVE):   The curve showing
the relationship between the dry unit weight (density) and the water content
of a soil for a given compactive effort.

COMPACTION TEST (MOISTURE-DENSITY TEST):   A laboratory compacting procedure
whereby a soil at a known water content is placed in a specified manner into a
mold of given dimensions, subjected to a compactive effort of controlled
magnitude, and the resulting unit weight determined.  The procedure is repeated
for various water contents sufficient to establish a relation between water
content and unit weight.                                          I

COMPANION CROP:  Seeding of a short-life crop with the permanent species to
aid in erosion control until the permanent species are established.

COMPRESSIBILITY:  Property of a soil pertaining to its susceptibility to
decrease in volume when subjected to load.

COMPRESSIVE STRENGTH (UNCONFINED COMPRESSIVE STRENGTH):  The load per unit
area at which an unconfined prismatic or cylindrical specimen of soil will
fail in a simple compression test.                                      N

CONSISTENCY:  The relative ease with which a soil can be deformed.

CONSOLIDATED DRAINED TEST (SLOW TEST):  A soil test in which essentially
complete consolidation under the confining pressure is followed by additional
axial (or shear) stress applied in such a manner that even a fully saturated
soil of low permeability can adapt itself completely (fully consolidate) to
the changes in stress due to the additional axial (or shear) stress.

CONSOLIDATED UNDRAINED TEST (CONSOLIDATED QUICK TEST):  A test in which com-
plete consolidation under the vertical load (in a direct shear test) or under
the confining pressure (in a triaxial test) is followed by a shear at constant
water content.

CONSOLIDATION TEST:  A test in which the  specimen is laterally confined in a
ring and is compressed between porous plates.

CONSOLIDATION-TIME CURVE (TIME CURVE) (CONSOLIDATION CURVE) (THEORETICAL TIME
CURVE):  A  curve that shows the relation  between (1) the degree of consolida-
tion and (2) the elapsed time after the application of a given increment of
load.

CONTOUR:  1.  An imaginary  line on the surface of the earth connecting points
of  the same elevation.  2.  A line drawn  on a map connecting points of the
same elevation.

COOL-SEASON PLANT:  A plant that  makes its major growth during the cool portion
of  the year, primarily  in the spring  but  in some localities in the winter.

COURSE:  See  "Lift."
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COVER, FINAL:  The cover material that is applied at the end of the useful
life of a disposal site and represents the permanently exposed final surface
of the fill.

COVER MATERIAL:  A soil or other suitable material that is used to cover the
liner or wastes in a disposal site.

CROSSLINKING:  A general term referring to the formation of chemical bonds
between polymeric chains to yield an insoluble, three-dimensional polymeric
structure.  Crosslinking of rubbers is vulcanization, q.v.

CRITICAL POINT:  (Physical Chemistry) For a given substance, temperature and
pressure above which no meniscus can form, so that liquid and gaseous phases
become indistinguishable.

CULTIVAR:  An assemblage of cultivated plants which is clearly distinguished
by its characters (morphological, physiological, cytological, chemical, or
others) and which when reproduced (sexually or asexually), retains those dis-
tinguishing characters.  The terms "cultivar" and "variety" are equivalents.

CURING:  See "Vulcanization."

CUT:   Portion of land surface or area from which earth has been removed or
will  be removed by excavation; the depth below original ground surface to
excavated surface.

CUTBACK ASPHALT:  Asphalt cement that has been liquefied by blending with
petroleum solvents which are in this context also called diluents.  Upon
exposure to atmospheric conditions the diluents evaporate leaving the asphalt
cement to perform its function.

CUT-OFF TRENCH:  A trench that is filled with material that may be impermeable
or very permeable to the flow of a gas or water.  The barrier is used to
prevent the movement of gas or water or to intercept them and to direct them
to another location.

DEFORMATION:  Change in shape.

DEGREE OF SATURATION:  See "Percent Saturation."

DENSITY:   (in Soil Mechanics) see Unit Weight.

DIKE:  A barrier to the flow of surface waters.  It may be a raised embankment
or a ditch.

DILATANCY:  (in Soil  Mechanics) The volume change of cohesionless soils when
subject to shear deformation.

DISPERSION,  SOIL:   The breaking down of soil aggregates into individual parti-
cles, resulting in single-grain structure.  Ease of dispersion is an important
factor influencing the credibility of soils.  Generally speaking, the more
easily dispersed the soil, the more erodible it is.

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DISPERSIVITY:   Tendency toward dispersion.

DIVERSION DAM:   A barrier built to divert part or all  of the water from a
stream into a different course.

DOUBLE LAYER (ELECTRICAL DOUBLE LAYER,  DIFFUSE DOUBLE  LAYER):   In colloid
chemistry, the electric charges on the  surface of the  disperse phase (usually
negative), and the adjacent diffuse layer (usually positive) of ions in
solution.

DRILL SEEDING:   Planting seed with a drill  in relatively narrow rows, generally
less than a foot apart.

EDAPHIC FACTOR:   A condition or characteristic of the  soil (chemical, physical,
or biological) which influences organisms.

EFFECTIVE DIAMETER (EFFECTIVE SIZE):  Particle diameter corresponding to
10 percent finer on the grain-size curve.

EFFLUENT:  A liquid which flows out of  a containing space.

ELASTICITY:  The capability of a strained body to recover its size and shape
after deformation.

ELASTOMER:  See "Rubber."

ELEVATION HEAD:   Head possessed by an element of water by virtue of its eleva-
tion with respect to a level datum plane.   May be positive or negative.
Expressed in linear units (e.g. feet),  representing vertical distance from
datum.

ELONGATION:  See "Ultimate Elongation."

EMULSIFIED ASPHALT:  A mixture of asphalt and water in which the asphalt is
held in suspension in the water by an emulsifying agent.  Emulsified asphalts
may be either cationic or anionic depending on the emulsifying agent used.

EPDM:  A synthetic elastomer based on ethylene, propylene, and a small amount
of a nonconjugated diene to provide sites for vulcanization.  EPDM features
excellent heat, ozone and weathering resistance, and low-temperature
flexibility.

EPHEMERAL STREAM:  A stream or portion of a stream that flows only in direct
response to precipitation, and receives little or no water from springs or no
long-continued supply from snow or other sources, and its channel is at all
times above the water table.

EPICHLOROHYDRIN RUBBER:  This  synthetic rubber includes two epichlorohydrin-
based elastomers which are saturated, high-molecular-weight, aliphatic poly-
ethers with chloro-methyl side chains.   The two types include a homopolymer
(CO) and  a copolymer of epichlorohydrin and ethylene oxide  (ECO).


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These  rubbers are  vulcanized with a  variety  of  reagents  that  react  difunction-
ally with the chloromethyl group; including  diamines,  urea, thioureas,  2-
mercaptoimidazoline, and  ammonium salts.

EROSION:  1.  The  wearing away of a  land  surface by moving water, wind,  ice,
or other geological agents, including such processes as  gravitational creep.
2.  Detachment and movement of soil  or  rock  fragments  by water, wind, ice, or
gravity.

ESSENTIAL ELEMENT  (PLANT  NUTRITION):  A chemical element required for the
normal growth of plants.

EVA:   Family of  copolymers of ethylene  and vinyl acetate used for adhesives
and thermoplastic  modifiers.  They possess a wide range  of melt indexes.

EXCHANGE CAPACITY:  See "Cation exchange  capacity."

EXCHANGEABLE NUTRIENT:  A plant nutrient  that is held  by the adsorption  complex
of the soil and  is easily exchanged  with  the anion or  cation of neutral  salt
solutions.

EXPOSURE:  Direction of slope with respect to points of  a compass.

EXTRUDER:  A machine with a driven screw  for continuous  forming of  rubber by
forcing through a  die; can be used to manufacture films  and sheeting.

FERTILITY (SOIL):  The quality of a  soil  that enables  it to provide nutrients
in adequate amounts and in proper balance for the growth of specified plants
when other growth  factors, such as light, moisture, temperature, and the
physical condition of the soil, are  favorable.

FERTILIZER FORMULA:  The  quantity and grade of the crude stock materials used
in making a fertilizer mixture; for  example, one formula for a fertilizer with
an analysis of 5-10-5 could be 625 pounds of 16 percent  nitrate of  soda,
1,111  pounds of 18 percent superphosphate, 200 pounds  of 50 percent muriate of
potash, and 64 pounds of  filler per  ton.

FIELD CAPACITY:   The maximum amount  of moisture a soil  or solid waste can
retain in a gravitational  field without a continuous downward percolation.

FILM:   (Polymeric technology) Sheeting having nominal  thickness not greater
than 10 mils.

FILTER (PROTECTIVE FILTER):   A layer or combination of layers of pervious
materials designed and installed in  such a manner as to provide drainage, yet
prevent the movement of soil  particles due to flowing water.

FINES:   Portion of soil finer than a No. 200 United States standard sieve.

FLOC:   Loose,  open-structured mass formed in a suspension by the aggregation
of minute particles.


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FLOCCULATION:   The process of forming floes.

FLOCCULENT:   Containing, consisting of,  or occurring in the form of loosely
aggregated particles or soft flakes;  made up of floes.

FLORA:   The sum total of the types of plants in an area at one time.

FLOW CHANNEL:   The portion of a flow net bounded by two adjacent flow lines;
any channel  through which a fluid may flow.

FLOW LINE:  The path that a particle of water follows in its course of seepage
under laminar flow conditions.

FLOW NET:   A graphical representation of flow lines and equipotential lines
used in the study of seepage phenomena.

FLUX:  (fluid flow) flow concentration:   volumetric flow rate divided by area.

FLY ASH:   Fine solid particles of noncombustible ash carried out of a bed of
solid fuel by the combustion draft and either deposited in quiet spots in
furnaces or flues or carried up the stack.

FOOTING:   Portion of the foundation of a structure that transmits loads direct-
ly to the soil.

FORB:  A herbaceous plant which is not a grass, sedge,  or rush.   A broadleaf
herb or weed.

FREE WATER (GRAVITATIONAL WATER) (GROUND WATER) (PHREATIC WATER):  Water that
is free to move through a soil mass under the influence of gravity.

FREE WATER ELEVATION (see WATER TABLE)

FROST ACTION:   Freezing and thawing of moisture in materials and the resultant
effects on these materials and on structures of which they are a part or with
which they are in contact.

FROST HEAVE:  The raising of a surface due to the accumulation of  ice in the
underlying soil.

FUNGI:  Simple plants that lack a photosynthetic pigment.

GABION:   A rectangular  or cylindrical wire mesh cage filled with rock and  used
as a protecting apron,  revetment, etc., against erosion.

GEOMEMBRANE:   A flexible, Impervious,thin sheet of rubber or plastic material
used primarily for  linings and covers of  liquid or solid storage impoundments,
thus serving  as a moisture barrier.

GEOTEXTILE:   A flexible,  porous  (to water flow), synthetic fabric used in
soil construction  for applications such as separation, reinforcement,
filtration,or drainage.

GLACIAL  TILL  (TILL): Material  deposited  by  glaciation,  usually  composed of  a
wide range  of particle  sizes,  which has not  been  subjected  to the  sorting
action of water.
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GRADATION (GRAIN-SIZE DISTRIBUTION) (PARTICLE-SIZE DISTRIBUTION) (SOIL TEXTURE):
Proportion of material of each grain size present in a given soil.

GRADE:  1.  The slope of a road, channel, or natural ground.  2.  The finished
surface of a canal bed, roadbed, top of embankment, or bottom of excavation;
any surface prepared for the support of construction like paving or laying a
conduit.  3.  To finish the surface of a canal bed, roadbed, top of embankment,
or bottom of excavation.

GRADIENT:  The degree of slope or a rate of change of a parameter measured
over distance.

GRAIN SIZE ANALYSIS (MECHANICAL ANALYSIS):  The process of determining
gradation of soil.

GRAVEL:  Unconsolidated granular mineral material of pebble sizes; rounded or
semirounded particles of rock that will pass a 3-inch and be retained on a
No. 4 United States standard sieve.  See Figure 3-3.

GRAVITATIONAL WATER:   Water which moves into, through, or out of the soil
under the influence of gravity.

GROUND COVER:  Grasses or other plants grown to keep soil from being blown or
washed away.

GROUND WATER, CONFINED:  (see ARTESIAN)

GROUND WATER, PERCHED:   Unconfined ground water separated from an underlying
body of ground water by an unsaturated zone.  Its water table is a perched
water table.  It is held up by a perching bed whose permeability is so low
that water percolating downward through it is not able to bring water in the
underlying unsaturated zone above atmospheric pressure.   Perched ground water
may be either permanent, where recharge is frequent enough to maintain a
saturated zone above the perching bed, or temporary, where intermittent re-
charge is not great or frequent enough to prevent the perched water from
disappearing from time to time as a result of drainage over the edge of or
through the perching bed.

GROUND WATER, UNCONFINED:   Water in an aquifer that has a water table.

GROUT:  A cementing or sealing mixture which may be injected, poured,  or
otherwise introduced into a confined or unconfined space in a fluid condition,
and which after introduction sets up to perform its cementing or sealing
function.

GROWING SEASON:   The period and/or number of days between the last freeze in
the spring and the first frost in the fall for the freeze threshold temperature
of the crop or other designated temperature threshold.

GULLY:  A channel or miniature valley cut by concentrated runoff but through
which water commonly flows only during and immediately after heavy rains or
during the melting of snow; may be dendritic or branching or it may be linear,

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rather long, narrow,  and of uniform width.   The distinction between gully and
rill  is one of depth.   A gully is sufficiently deep that it would not be
obliterated by normal  tillage operations,  whereas a rill is of lesser depth
and would be smoothed by ordinary farm tillage.

HALOPHYTE:   A plant adapted to existence in a saline environment.

HARDPAN:   A hardened soil  layer in the lower A or in the B horizon caused by
cementation of soil particles with organic matter or with materials such as
silica, sesquioxides,  or calcium carbonate.   The hardness does not change
appreciably with changes in the moisture content, and pieces of the hard layer
do not slake in water.

HAZARDOUS WASTE:  A solid waste or combination of solid wastes, which because
of its quantity, concentration or physical,  chemical, or infectious character-
istics may:
         A.  Cause, or significantly contribute to an increase in mortality or
      an increase in serious irreversible, or incapacitating reversible,
      illness; or
         B.  Pose a substantial present or potential hazard to human health or
      the environment when improperly treated, stored, transported, or dis-
      posed of, or otherwise managed (Public Law 94-580, 1976).

HEAD:   A measure of the energy that water possesses by virtue of its elevation,
pressure, or velocity.   The components Elevation Head, Pressure Head, and
Velocity Head (q.q.v.) combine to make Total Head.  All heads are expressed in
linear units, e.g. feet.  See also Static Head.   At all points in a body of
water at rest, the total head (equals static head) is the same, pressure heads
exactly compensating elevation heads, and velocity heads being zero.  Water
flows spontaneously from points of higher to points of lower total head.

HEAT SEAMING:  The process of joining two or more thermoplastic films or
sheets by heating areas in contact with each other to the temperature at which
fusion occurs.

HEAVE:  Upward movement of soil caused by expansion or displacement resulting
from phenomena such as:  moisture absorption, removal of overburden, driving
of piles, and frost action.

HEAVY METALS:  Any of the metals that react readily with dithizone.  They  in-
clude bismuth, cadmium, cobalt, chromium, copper, gold, iron, manganese,
mercury, nickel,  lead, and zinc.

HERB:  Any  flowering plant except those developing persistent woody bases  and
stems above  the ground.

HORIZON  (SOIL HORIZON):  One of the  layers  of the soil  profile, distinguished
principally  by  its texture,  color,  structure, and chemical  content.
         A  HORIZON:  The uppermost layer of  a  soil profile  from which  inorganic
       colloids  and other soluble materials  have  been  leached.  Usually  contains
       remnants  of organic  life.
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        B HORIZON:  The layer of a soil profile in which material leached from
      the overlying A horizon is accumulated.

        C HORIZON:  Undisturbed parent material from which the overlying soil
      profile has been developed.

HUMUS:  A brown or black material formed by the partial decomposition of
vegetable or animal matter; the organic portion of soil.

HYDRAULIC ASPHALT CONCRETE:  Similar to asphalt concrete designed for roadway
paving, except that it has a higher mineral filler and asphalt content in
order to insure an essentially voidless mix after compaction.

HYDRAULIC CONDUCTIVITY:   Term used in ground-water hydrology and soil science.
Equivalent to Coefficient of Permeability, q.v.

HYDRAULIC GRADIENT:  The loss of hydraulic head per unit distance of flow, ^ .

HYDROSTATIC PRESSURE:   The pressure in a liquid under static conditions; the
product of the unit weight of the liquid and the difference in elevation
between the given point and the free water elevation.

HYDROPHYTE:  A plant that grows in water or in wet or saturated soils.

HYGROSCOPIC CAPACITY (HYGROSCOPIC COEFFICIENT):  Ratio of (1) the weight of
water absorbed by a dry soil in a saturated atmosphere at a given temperature
to (2) the weight of the oven-dried soil.

HYGROSCOPIC WATER CONTENT:   The water content of an air-dried soil.

ILLITE:  A very common clay mineral of uncertain specificity also termed
"hydrous mica" or "clay mica," of moderate specific surface and fairly low
exchange capacity, rarely if ever found pure.

IMPERMEABLE:   Not permitting passage of a fluid or a gas through its substance.

IMPERVIOUS:  See "Impermeable."

IMPOUNDMENT:   See "Surface Impoundment."

IN SITU:  In its natural or original position.

INDICATOR PLANTS:   Plants characteristic of specific soil or site conditions.

INDUSTRIAL WASTE:   Waste from industrial processes as  distinct from municipal
solid waste.

INFILTRATION:   The downward entry of water into the soil.
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INFILTRATION RATE (INFILTRATION CAPACITY):   A soil  characteristic determining
the maximum rate at which water can enter the soil  under specified conditions,
including the presence of an excess of water.  It has the dimensions of
velocity.

INFILTRATION VELOCITY:   The actual  rate at which water rs entering the soil  at
any given time.   It may be less than the maximum (the infiltration rate)
because of a limited supply of water (rainfall  or irrigation).   It has the
same units as infiltration rate.

INOCULATION:  The process of introducing pure or mixed cultures of microorgan-
isms into natural or artificial culture media.

INTERCEPTOR DRAIN:   Surface or subsurface drain, or a combination of both,
designed and installed to intercept flowing water.

INTERNAL FRICTION:   The portion of  the shear strength of a soil indicated by
the terms  p tan 0  in Coulomb's  equation  s = c +  p tan 0 .   It is usually
considered to be due to the interlocking of the soil grains and the resistance
to sliding between the grains.

INTERSEEDING:  Seeding into an established vegetation.

INTERSTICE:  An opening or space  between one thing  and another, as an opening
in a rock or soil that is not occupied by solid matter.   Synonyms = void,
pore.

INTRINSIC PERMEABILITY:   A measure  of the relative  ease with which a porous
medium can transmit a liquid under  a potential  gradient.   It is a property of
the medium alone and is independent of the nature of the liquid and of the
force field causing movement (assuming no alteration of the medium by the
liquid).  It is dependent upon the  shape and size of the pores.

INVADER PLANT SPECIES:   Plant species that were absent in undisturbed portions
of the original plant community and will invade under disturbance or continued
overuse.  Commonly termed invaders.

ISOTROPIC MASS:   A mass having the  same property (or properties) in all
directions.

JULIAN DATE:  In common usage, e.g., military and computer, the calendar date
expressed as a series of digits,  sequenced throughout the year.  Commonly, four
digits of which the first represents the year,  the  last three the day, e.g.,
9364 is December 30, 1979 (or 1969, 1989, ...).

KAOLIN:  A variety of clay containing a high percentage of kaolinite.

KAOLINITE:  A common clay mineral of relatively simple and constant chemistry
and low specific surface, activity, and exchange capacity.
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 LAMINAR  FLOW (STREAMLINE  FLOW)  (VISCOUS  FLOW):   Flow in  which  each  fluid
 particle moves  in  a  direction parallel to  every other particle,  and in  which
 the  head loss  is proportional to  the  first power of  the  velocity.

 LANGLEY:   A  unit of  solar radiation equivalent  to one gram  calorie  per  square
 centimeter of  irradiated  surface.

 LAPPED JOINT:   A joint  made  by  placing one surface to be joined  partly  over
 another  surface and  bonding  the overlapping portions.

 LEACHATE:  Liquid  that  has percolated through or drained from  a  material  and
 contains soluble,  partially  soluble, or  miscible components  removed from  such
 material.

 LEACHED  SOIL:   A soil from which  most of the soluble  materials (CaCO- and
 MgC03 and  more  soluble  materials)  have been removed  from the entire profile or
 have been  removed  from  one part of the profile  and have  accumulated in  another
 part.

 LEACHING:  The  removal  from  the soil in  solution of  the  more soluble materials
 by percolating  waters.

 LEGUME:  A member  of the  pulse  family.   Includes many  valuable food and forage
 species, such as peas,  beans, peanuts, clovers,  alfalfas, sweet  clovers,
 lespedezas,  vetches, and  kudzu.    Practically all  legumes  are nitrogen-fixing
 plants.

 LEGUME INOCULATION:  The  addition  of nitrogen-fixing bacteria to legume seed
 or to the  soil  in  which the  seed  is to be  planted.

 LIFT:  A single layer of  compacted soil.    Lift  thickness  depends on soil  and
 degree of compaction needed  (also  termed "course").

 LIME:  From  the strictly  chemical   standpoint, refers to only one compound,
 calcium  oxide (CaO); however, the  term is  commonly used  in agriculture to
 include  a great variety of materials that  are usually composed of the oxide,
 hydroxide, or carbonate of calcium or of calcium  and magnesium; used to furnish
 calcium  and  magnesium as  essential elements  for  the growth of plants and  to
 neutralize soil acidity.  The most commonly  used  forms of agricultural lime
 are ground limestone (carbonates), hydrated  lime  (hydroxides),  burnt lime
 (oxides), marl, and oyster shells.

 LINEAR EXPANSION:   The increase  in one dimension of a soil mass,  expressed as
 a percentage of that dimension at the shrinkage  limit, when the water content
 is increased from the shrinkage  limit to  any given water content.

 LINEAR SHRINKAGE:   Decrease in one dimension of a soil mass, expressed as a
percentage of the original dimension,  when the water content is reduced from a
given value to the  shrinkage  limit.
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LINER:  A layer of emplaced material beneath a surface impoundment or landfill
which is intended to restrict the escape of waste or its constituents from the
impoundment or landfill.   May include:   reworked or compacted soil and clay,
asphaltic and concrete materials, spray-on membranes, polymeric membranes,
chemisorptive substances, or any substance that serves the above stated
purpose.

LIQUID LIMIT:   (1)  The water content corresponding to the arbitrary limit
between the liquid and plastic states of consistency of a soil.   (2)  The
water content at which a pat of soil, cut by a groove of standard dimensions,
will flow together for a distance of one-half inch under the impact of 25
blows in a standard liquid limit apparatus.

LOAM:  A mixture of sand, silt, or clay, or a combination of any of these,
with organic matter (humus).   It is sometimes called topsoil in contrast to
the subsoils that contain little or no organic matter.   A textural name for
soils of certain gradations in the agricultural system.

LOESS:  A uniform aeolian deposit of silty material having an open structure
and relatively high cohesion due to cementation of clay or calcareous material
at grain contacts.  A characteristic of loess deposits is that they can stand
with nearly vertical slopes.   Loess has high vertical permeability.

LYSIMETER:   A device used to measure the quantity or rate of water movement
through or from a block of soil or other material, such as solid waste, or
used to collect percolated water for qualitative analysis.

MACRONUTRIENT:  A chemical element necessary in large amounts (always greater
than one part per million) for the growth of plants; usually applied artifi-
cially in fertilizer or liming materials.  "Macro" refers to quantity and not
the essentiality of the element.  Examples are nitrogen, phosphorus, potassium
and calcium.  See micronutrient.

MACROORGANISMS:  Those organisms retained on a U. S. standard sieve no. 30
(openings of 0.589 mm); those organisms visible to the unaided eye.  See
microorganisms.

MASTIC:  A mixture of mineral aggregate, mineral filler, and asphalt in such
proportions that the mix can be applied hot by pouring or by mechanical mani-
pulation; it forms a voidless mass without being compacted.

MECHANICAL ANALYSIS:  See "Grain Size Analysis."

MESOPHYTE:  A plant that grows under intermediate moisture conditions.

MICROCLIMATE:  1.  The climatic condition of a small area resulting from the
modification of the general climatic conditions by  local differences in eleva-
tion or exposure.  2.  The sequence of atmospheric  changes within  a very small
region.
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MICRONUTRIENT:  A  chemical  element  necessary  in  only  extremely  small  amounts
for the growth of  plants.   "Micro"  refers  to  the amount  used  rather  than  to
its essentiality.   Examples  are  boron, chlorine,  copper,  iron,  manganese,  and
zinc.  See macronutrient.

MICROORGANISMS:  Those organisms  retained  on  a U.  S.  standard sieve  no. 100
(openings of 0.149 mm);  those minute organisms invisible  or only barely visible
to the unaided eye.  See macroorganisms.

MIL:  Unit of length, equal  to .001 inch or .0254 mm.

MINERAL FILLER:  A finely divided mineral  product of  which at least  65% will
pass a No. 200 sieve which  has a  sieve opening of 74  \jm.  Pulverized  limestone
is the most common manufactured  filler, although other stone  dust, silica,
hydrated  lime, portland  cement,  and certain natural deposits  of finely divided
matter are also used.

MODULUS OF ELASTICITY (MODULUS OF DEFORMATION):   The  ratio of stress  to strain
for a material under given  loading conditions; numerically equal to  the slope
of the tangent or  the secant of  a stress-strain  curve.

MOISTURE CONTENT:   See "Water Content."

MONITORING:   All procedures  used to systematically inspect and collect data on
operational  parameters of a  facility or on the quality of the air, ground
water, surface water or  soil.

MONITORING WELL:   A well used to obtain water samples for water quality analy-
sis or to measure  ground-water levels.

MONTMORILLONITE:   A common clay mineral of complex and variable chemistry,
high to extremely  high specific  surface and activity, and high exchange
capacity.   Montmorillonite is the essential component of bentonite, q.v.
A general  group term proposed for montmorillonite-1ike minerals is "smectite."
Montmorillonites swell  by absorbing water within  their crystal lattice, leading
to variable interlayer spacing.

MUCK:   An organic  soil  of very soft consistency.

MULCH:   A natural  or artificial   layer of plant residue or other materials,
such as sand or paper,  on the soil surface.

MUNICIPAL SOLID WASTE:   Solid waste collected from residential and commercial
sources in bins and other large containers.

NATIVE SPECIES:   A species that is part of an area's original  fauna or flora.

NATURAL REVEGETATION:   Natural  reestablishment of plants; propagation of new
plants  over  an area by  natural  processes.
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NEOPRENE (POLYCHLOROPRENE):   Generic name for a synthetic rubber based primar-
ily on chloroprene, i.e.  chlorobutadiene.  Vulcanized generally with metal
oxide.  Resistant to ozone and aging and to some oils.

NITRILE RUBBER:  A family of copolymers of butadiene and acrylonitrile that
can be vulcanized into tough, oil-resistant compounds.   Blends with PVC are
used where ozone and weathering are important requirements in addition to its
inherent oil and fuel resistance.

NITROGEN-FIXING PLANT:  A plant that can assimilate and fix the free nitrogen
of the atmosphere with the aid of bacteria living in the root nodules.   Legumes
with the associated rhizobium bacterial in the root nodules are the most
important nitrogen-fixing plants.

NORMALLY CONSOLIDATED SOIL DEPOSIT:  A soil deposit that has never been sub-
jected to a pressure greater than the existing overburden pressure.

NOXIOUS SPECIES:  A plant that is undesirable because it conflicts, restricts,
or otherwise causes problems under the management objectives.  Not to be
confused with species declared noxious by laws.

NUTRIENTS:  1.   Elements, or compounds, essential as raw materials for organism
growth and development, such as carbon, oxygen,  nitrogen, phosphorus, etc.
2.  The dissolved solids and gases of the water of an area.

OPTIMUM MOISTURE CONTENT (OPTIMUM WATER CONTENT):  The water content at which
a soil can be compacted to the maximum dry unit weight by a given compactive
effort.

ORGANIC SOIL:   Soil with a high organic content.   In general, organic soils
are very compressible and have poor load-sustaining properties.

OVENDRY SOIL:   Soil which has been dried at 105°C until it reaches a constant
weight.

OVERCONSOLIDATED SOIL DEPOSIT:   A soil deposit that has been subjected to
pressure greater than the present overburden pressure.

PAN:   Horizon or layer in soil  that is strongly compacted, indurated, or very
high in clay content, e.g.,  claypan, fragipan, hardpan.

PARENT MATERIAL:  Material from which a soil has been derived.

PARTICLE SIZE:   The effective diameter of a particle measured by sedimentation,
sieving, or micrometric methods.

PARTICLE SIZE DISTRIBUTION:   See "Gradation."

PEAT:   A fibrous mass of organic matter in various stages of decomposition,
generally dark brown to black in color and of spongy consistency.
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PEBBLE:  Rock particle, commonly rounded from natural abrasion, of a size
larger than sand and smaller than cobbles, thus approximately 3 to 75 mm.

PERCENT SATURATION:  The ratio, expressed as a percentage, of (1) the volume
of water in a given soil mass to (2) the total volume of intergranular space
(voids).

PERCHED WATER TABLE:  A water table usually of limited area maintained above
the normal free water elevation by the presence of an intervening relatively
impervious confining stratum.

PERCOLATION:   Downward movement of water through soil.  Especially, the down-
ward flow of water in saturated or near-saturated soil at hydraulic gradients
of the order of 1.0 or less.

PERENNIAL PLANT:  A plant that normally lives three or more years.

PERMEABILITY:  Capability of a material to transmit fluid through its
substance.  See "Coefficient of Permeability," "Hydraulic Conductivity," and
"Intrinsic Permeability."

PESTICIDE:  Chemical agent used to kill animal and vegetable life which inter-
feres with agricultural productivity.

pH:  Logarithm of the reciprocal of the hydrogen ion concentration in water or
an aqueous solution.  Neutral is pH 7.0.   All pH values below 7.0 are acid,
and all above 7.0 are alkaline or basic.

PHASE:  A homogeneous part of a chemical  system, separated from other parts by
physical boundaries.

PHREATOPHYTE:  A plant deriving its water from subsurface sources;  commonly
used to describe nonbeneficial, water-loving vegetation.

PIEZOMETER:   An instrument for measuring pressure head.

PIPING:  The movement of soil particles by percolating or seeping water leading
to the development of channels and internal erosion.

PLANT SUCCESSION:   The process of vegetation development whereby an area
becomes successively occupied by different plant communities of higher ecolog-
ical order.

PLANTING SEASON:  The period of the year when planting or transplanting is
considered advisable from the standpoint of successful establishment.

PLASTIC FLOW (PLASTIC DEFORMATION):   The deformation of a plastic material
beyond the point of recovery, accompanied by continuing deformation with no
further increase in stress.
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PLASTIC LIMIT:  (1) The water content corresponding to an arbitrary limit
between the plastic and the semisolid states of consistency of a soil.
(2) Water content at which a soil will just begin to crumble when rolled into
a thread approximately one-eighth inch in diameter.

PLASTIC STATE (PLASTIC RANGE):   The range of consistency within which a soil
exhibits plastic properties.

PLASTICITY:  The property of a soil which allows it to be deformed beyond the
point of recovery without cracking or appreciable volume change.

PLASTICITY INDEX:   Numerical  difference between the liquid limit and the
plastic limit.

PLASTICIZER:   A plasticizer is a material, frequently "solvent-like," incor-
porated in a plastic or a rubber to increase its ease of workability, its
flexibility,  or extensibility.   Adding the plasticizer may lower the melt
viscosity, the temperature of the second order transition, or the elastic
modulus of the polymer.  Plasticizers may be monomeric liquids (phthalate
esters), low molecular weight liquid polymers (polyesters) or rubbery high
polymers (E/VA).   The most important use of plasticizers is with PVC where the
choice of plasticizer will dictate under what conditions the liner may be
used.

POLYESTER FIBER:   Generic name for a manufactured fiber in which the fiber-
forming substance is any long chain synthetic polymer composed of an ester of
a dihydric alcohol  and terephthalic acid.   Scrims made of polyester fiber are
used for fabric reinforcement.

POLYMER:  A macromolecular material  formed by the chemical combination of
monomers having either the same or different chemical  composition.   Plastics,
rubbers, and  textile fibers are all  high molecular weight polymers.

POLYMERIC LINER:   Plastic or  rubber sheeting used to line disposal  sites,
pits,  ponds,  lagoons,  canals,  etc.

POLYVINYL CHLORIDE  (PVC):   A  synthetic thermoplastic polymer prepared from
vinylchloride.  PVC can be compounded into flexible and rigid forms through
the use of plasticizers,  stabilizers, fillers,  and other modifiers; rigid
forms  used in pipes and well  screens; flexible  forms used in manufacture of
sheeting.

PORE:   A small to  minute opening or passageway  in a rock or soil; an
interstice.

POROSITY:   The ratio,  usually expressed as a percentage, of (1) the volume of
voids  of a given soil  mass to (2) the total  volume of the soil mass.

PORTLAND CEMENT:   A hydraulic cement made by burning and grinding a mixture of
calcareous and argillaceous materials, e.g., limestone and clay.
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 PRESSURE:   Intensity  of  loading.   The  load divided by the area over which it
 acts.   A  scalar  quantity.   Cf.  "stress."

 PRESSURE  HEAD:   Head  possessed  by  an element  of water by virtue of its
 pressure.   Expressed  in  linear  units (e.g.  feet).   Equal  to  the depth below a
 free  surface  that  would  produce the existing  pressure under  static conditions.

 PRESSURE/VOID-RATIO CURVE:   A curve representing the  relationship  between
 pressure  and  void  ratio  of  a soil  as obtained from a  consolidation test.

 PRINCIPAL  PLANE:   Each of three mutually  perpendicular planes  through a  point
 in a  solid mass  on which the shearing  stress  is zero.

 PROCTOR COMPACTION CURVE:   See  "Compaction  Curve."

 PUNCTURE  RESISTANCE:  Extent to which  a material  is able  to  withstand the
 action of  a sharp  object without perforation.

 QUICK TEST:   See "Unconsolidated Undrained  Test."

 RELATIVE DENSITY:  The ratio of (1) the difference between the  void  ratio of a
 cohesionless  soil  in  the loosest state and  any  given  void ratio  to  (2) the
 difference between its void  ratios in  the  loosest  and  in  the densest states.

 REMOLDED SOIL:  Soil  that has had  its  natural structure modified by
 manipulation.

 RESIDUAL SOIL:  Soil  derived in place by weathering of the underlying material.

 REVEGETATION:   Plants or growth  that replaces original ground cover following
 land disturbance.

 RHIZOME:  A horizontal underground stem, usually sending out roots and above-
 ground shoots at the  nodes.

 RIPRAP:   Broken rock,  cobbles,   or boulders placed on earth surfaces, such as
 the face of a dam or  the bank of a stream, for  protection against the action
 of water (waves); also applied  to brush or pole mattresses, or brush and
 stone, or other similar materials used for soil erosion control.

 ROCK FLOUR:  See "Silt."

 ROLL GOODS:  A general term  applied to rubber and plastic sheeting whether
 fabric reinforced or  not.  It is usually furnished in rolls.

 ROOT ZONE:  The part  of the  soil that is penetrated or can be penetrated  by
plant roots.

 RUBBER:   A polymeric material which,  at room temperature, is capable of recov-
ering substantially in shape and size after removal of a deforming force.
Refers to both synthetic and natural  rubber.  Also called an elastomer.


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RUNOFF:  That portion of precipitation or irrigation water that drains from an
area as surface flow.

SALINE SOIL:  A nonsodic soil containing sufficient soluble salts to impair
its productivity but not containing excessive exchangeable sodium.

SAND:  Unconsolidated granular mineral material of a certain size range.
Particles of rock that will pass the No.  4 United States standard sieve and be
retained on the No.  200 sieve.  See Figure 3-3.

SANITARY LANDFILL (LAND FILLING):   A site where solid waste is disposed of on
land in a manner designed to protect the environment by spreading the waste in
thin layers, compacting it to the smallest practical volume, and then covering
it with soil by the end of the working day.

SCARIFY:  To break up and loosen a surface.

SCRIM:   A woven, open-mesh reinforcing fabric made from continuous-filament
yarn.  Used in the reinforcement of polymeric sheeting.

SEAM STRENGTH:   Strength of a seam of liner material measured either in shear
or peel modes.   Strength of the seams is reported either in absolute units,
e.g. pounds per inch of width, or as a percent of the strength of the sheeting.

SEED:  The fertilized and ripened ovule of a seed plant that is capable,  under
suitable conditions, of independently developing into a plant similar to the
one that produced it.  Types of seed include:

        Breeder $eed:  Seed or vegetative propagating material directly con-
      trolled by the originating,  or in some cases the sponsoring plant
      breeder,  institution, or firm, and which supplies the initial and recur-
      ring increase of foundation seed.

        Certified seed:  The progeny of foundation or registered seed that is
      so handled as to maintain satisfactory genetic identity and purity and
      that has been approved and certified by the certifying agency.
        Commercial seed:  A term used to designate other than recognized
      varieties of seed in commercial channels.
        Common seed:  Noncertified seed.   It may be a named variety, but not
      grown under the certification program.
        Dormant seed:  An internal condition of the chemistry or stage of
      development of a viable seed that prevents its germination, although
      good growing temperatures and moisture are provided.

        Firm seed:  Dormant seeds, other than hard seeds, that neither germi-
      nate nor decay during the prescribed test period under the prescribed
      conditions.  Firm ungerminated seeds may be alive or dead.

        Foundation seed:  Seed stocks that are so handled as to most nearly
      maintain specific genetic identity and purity.  Production must be
      carefully supervised by the certifying agency and/or the agricultural
      experiment station.

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        Hard seed:  A physiological condition of seed in which some seeds do
      not absorb water or oxygen and germinate when a favorable environment is
      provided.

        Registered seed:  The program of foundation seed that is so handled as
      to maintain satisfactory genetic identity and purity and that has been
      approved and certified by the certifying agency.  This class of seed
      should be of a quality suitable for production of certified seed.

SEED PURITY:  The percentage of the desired species in relation to the total
quantity of other species, weed seed, and foreign matter.

SEEDBED:  The soil prepared by natural or artificial means to promote the
germination of seed and the growth of seedlings.

SEEPAGE:  Slow movement of water through soil.

SENSITIVITY:  The effect of remolding on the consistency of a cohesive soil.

SHAKING TEST:   A test used to indicate the presence of significant amounts of
rock flour, silt, or very fine sand in a fine-grained soil.  It consists of
shaking a pat of wet soil, having a consistency of thick paste, in the palm of
the hand; observing the surface for a glossy or livery appearance; then
squeezing the pat; and observing if a rapid apparent drying and subsequent
cracking of the soil occurs.

SHEETING:  A form of plastic or rubber in which the thickness is very small  in
proportion to length and width and in which the polymer compound is present as
a continuous phase throughout, with or without fabric.

SHRINKAGE LIMIT:   The maximum water content at which a reduction in water con-
tent will not cause a decrease in volume of the soil mass.

SHRUB:   A woody perennial plant differing from a tree by its low stature and
by generally producing several basal shoots instead of a single bole.

SILT (INORGANIC SILT) (ROCK FLOUR):   Material  passing the No.  200 United
States standard sieve that is nonplastic or very slightly plastic and that
exhibits little or no strength when air-dried.

SILT SIZE:   That portion of the soil finer than 0.02 mm.  and coarser than
0.002 mm. (0.05 mm.  and 0.005 mm.  in some cases).   See Figure 3-3.

SLAKING:  The process of breaking up or sloughing when an indurated soil  is
immersed in water.

SLOPE:   Deviation of a surface from the horizontal  expressed as a percentage,
by a ratio, or in degrees.   In engineering,  usually expressed as a ratio of
horizontal:vertical  change.   (Also see "grade.")
                                                .—	1
                                                          1
                                                              Slope = 6:1
                                                            (16.7%) (9.5°)


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SLOW TEST:   See "Consolidated-Drained Test."

SMECTITE:   See "Montmorillonite."

SOD:   A closely knit ground-cover growth, primarily of grasses.

SODIC SOIL:   1.  A soil  that contains sufficient sodium to interfere with the
growth of most crop plants.   2.   A soil  in which the exchangeable-sodium
percentage is 15 or more.   Sodic  soils,  because of dispersion of the organic
matter, have been called black alkali soils; sometimes also called nonsaline-
alkali soils.

SOFTENING POINT:   Temperature at  which a bitumen softens in the ring-and-bal1
method described in ASTM D2398.   Used in the classification of bitumen, par-
ticularly of bitumen intending for roofing, because it is indicative of the
tendency of a material  to flow at elevated temperatures encountered in service.

SOIL:  In engineering,  sediments  or other unconsolidated accumulations of
solid particles produced by the physical and chemical  disintegration of rocks,
and which may or may not contain  organic matter.

SOIL ASPHALT:  A compacted mixture of soil and asphalt cement.   Cutback or
emulsified asphalts are usually avoided.

SOIL CEMENT:  A tightly compacted mixture of pulverized soil, portland cement
and water that, as the  cement hydrates,  forms a hard,  durable,  low-strength
concrete-like material.

SOIL HORIZON:  See "horizon."

SOIL MECHANICS:  The application  of the  laws and principles of mechanics and
hydraulics to engineering problems dealing with the behavior and nature of
soil  as an engineering  material.

SOIL ORGANIC MATTER:   The organic fraction of the soil that includes plant and
animal residues at various stages of decomposition, cells and tissues of soil
organisms,  and substances synthesized by the soil population.  Commonly deter-
mined as the amount of  organic material  contained in a soil sample passed
through a 2-millimeter  sieve.

SOIL PROFILE (PROFILE):   Vertical section of a soil, showing the nature and
sequence of the various layers,  as developed by deposition or weathering, or
both.

SOIL SCIENCE:  The study of soil  as a natural material; also termed pedology.

SOIL SOLUTION:  The aqueous liquid phase of the soil and its solutes consisting
of ions dissociated from the surfaces of the soil particles and of other
soluble materials.
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SOIL STABILIZATION:  Chemical or mechanical treatment designed to increase or
maintain the stability of a mass of soil or otherwise to improve its engineer-
ing properties.

SOIL STERILANT:  Biocide applied to soils to prevent plant growth and insect
or disease infestation.

SOIL STRUCTURE:  In soil mechanics, the arrangement and state of aggregation
of soil particles in a soil mass.

        FLOCCULENT STRUCTURE:  An arrangement composed of floes of soil parti-
      cles instead of individual soil particles.

        SINGLE-GRAINED STRUCTURE:  An arrangement composed of individual soil
      particles; characteristic structure of coarse-grained soils.

SOIL SUCTION:  Tension ("negative pressure") existing in soil water under
unsaturated conditions.  A complex effect whose causes include capillarity,
adsorption, osmosis, etc.

SOLUM:   Genetic soil developed by soil-building forces; includes A and B soil
horizons, or upper part of soil profile above parent material.

SOLUTION:  A homogeneous mixture consisting of a single phase.

SPECIFIC RETENTION:  Ratio of (1) the volume of water which a rock or soil,
after being saturated, will retain against the pull of gravity to (2) the
volume of the rock or soil.

SPECIFIC SURFACE:  The ratio of the total surface area of a (finely divided)
substance to its volume; or, the surface area of a (finely divided) substance
per unit mass.

SPRAY BAR:  A long hollow tube with nozzles of any of a number of forms, used
to apply a thin layer or coat of a substance in liquid form.   Spray bars are
attached by hoses and pneumatic lines to pumps to convey the liquid from the
storage truck or tank to the nozzles.

SPRIGGING:  The planting of a portion of the stem and root of grass.

STATIC HEAD:   The sum of Elevation Head and Pressure Head, q.q.v.  See also
"Head."

STOLON:  A horizontal stem which grows along the surface of the soil  and roots
at the nodes.

STRAIN:  The change in length per unit of length in a given direction.

STRESS:  Intensity of force.  The force per unit area acting within a mass. A
vector quantity.  Cf. "pressure."
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        EFFECTIVE STRESS (EFFECTIVE PRESSURE) (INTERGRANULAR PRESSURE):   The
      average normal  force per unit area transmitted from grain to grain of a
      soil mass.   It is the stress that is effective in mobilizing internal
      friction.

        NEUTRAL STRESS (PORE PRESSURE) (PORE WATER PRESSURE):   Stress trans-
      mitted through the pore water (water filling the voids of the soil).

        NORMAL STRESS:   The stress component normal  to a given plane.

        SHEAR STRESS (SHEARING STRESS) (TANGENTIAL STRESS):   The stress  compo-
      nent tangential  to a given plane.

STRIKETHROUGH:  A term used in the manufacture of fabric-reinforced polymeric
sheeting to indicate that two layers of polymer have made bonding contact
through the scrim.

STRUCTURE:  See "soil  structure."

STUBBLE:  The basal portion of plants remaining after the top portion has been
harvested; also,  the portion of the plants, principally grasses, remaining
after grazing is  completed.

SUBBASE:  A layer used in a pavement system between the subgrade and base
course, or between the subgrade and portland-concrete pavement.

SUBGRADE:  The soil prepared and compacted to support a structure or a pavement
system.

SUBSIDENCE:  Settling or sinking of the land surface due to any of several
factors, such as  decomposition of organic material, consolidation, drainage,
and underground failure.

SUBSOIL:  The B horizons of soils with distinct profiles.  In soils with weak
profile development, the subsoil can be defined as the soil  below the plowed
soil (or its equivalent of surface soil), in which roots normally grow.
Although a common term, it cannot be defined accurately.  It has been carried
over from early days when "soil" was conceived only as the plowed soil and
that under it as  the "subsoil."

SUMP:  A pit or well at the lowest point of a circulating or drainage system,
in which liquids  collect.

SUPPLEMENTAL IRRIGATION:  Irrigation to insure or increase crop production in
areas where rainfall normally supplies most of the moisture needed.

SURFACE CURE:  Curing or vulcanization which occurs in a thin layer on the
surface of a manufactured polymeric sheet or other items.

SURFACE IMPOUNDMENT:   A natural or artificial basin used to contain liquid
wastes.  Includes pits, ponds, and lagoons.

SURFACE WATER:  All water whose surface is exposed directly to the atmosphere.


                                     E-28

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SUSPENSION:  A two-phase system consisting of a finely divided solid dispersed
in a solid, liquid, or gas.

SYMBIOSIS:  An arrangement whereby two organisms of different species live in
close association, from which one or both may benefit and neither is harmed.

TACKING:  The process of binding mulch fibers together by the addition of a
sprayed chemical compound.

TALUS:  Rock fragments mixed with soil at the foot of a natural slope from
which they have been separated.

TAR:  Dark, bituminous, viscous liquid obtained by destructive distillation of
wood, coal, peat, shale, or other natural materials.

TEAR STRENGTH:  The maximum force required to tear a specified specimen, the
force acting substantially parallel to the major axis of the test specimen.
Measured  in both initiated and uninitiated modes.  Obtained value is dependent
on specimen geometry, rate of extension, and type of fabric reinforcement.
Values are reported in stress, e.g. pounds, or stress per unit of thickness,
e.g. pounds per inch.

TENSILE STRENGTH:  The maximum tensile stress per unit of original cross-
sectional area applied during stretching of a specimen to break; units:  SI-
metric-megapascal or kilopascal; customary - pound per square inch.

TERRACE:  An embankment or combination of an embankment and channel  constructed
across a  slope to control erosion by diverting.

THERMOPLASTIC:  Capable of being repeatedly softened by increase of temperature
and hardened by decrease in temperature.  Most polymeric liners are supplied
in thermoplastic form because the thermoplastic form allows for easier seaming
both in the factory and in the field.

THERMOPLASTIC ELASTOMERS:  New materials which are being developed,  and which
are probably related to elasticized polyolefins.   Polymers of this type behave
similarly to crosslinked rubber.   They have a limited upper temperature service
range which, however, is substantially above the temperature encountered in
waste disposal sites (200°F may be too high for some TPE's).

TILE, DRAIN:  Pipe made of burned clay, concrete, or similar material in short
lengths, usually laid with open joints to collect and carry excess water from
the soil.

TILLAGE:  The operation of implements through the soil  to prepare seedbeds and
root beds.

TOLERANCE:  The relative ability of a species to survive a deficiency of an
essential  growth requirement,  such as moisture,  light or nutrient supply, or
an overabundance of a site factor such as excessive water, toxic salts, etc.

TONNE:   Metric ton; one thousand kilograms.

                                     E-29

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TOTAL HEAD:  See "Head."

TOXICITY:  Quality, state, or degree of being toxic or poisonous.

TOXIN:  (1) Any of various unstable poisonous compounds produced by some
microorganisms and causing certain diseases.   (2) Any of various similar
poisons, related to proteins, secreted by plants and animals.

TRANSPORTED SOIL:   Soil whose particles have been transported and deposited as
a sediment.

TREE:  A woody perennial plant that reaches a mature height of at least eight
feet and has a well-defined stem and a definite crown shape.   There is no
clear-cut distinction between trees and shrubs.  Some plants,  such as the
willows, may grow as either trees or shrubs.

TRIAXIAL SHEAR TEST (TRIAXIAL COMPRESSION TEST):  A test in which a cylindrical
specimen of soil encased in an impervious membrane is subjected to a confining
pressure and then loaded axially to failure.

TURBULENT FLOW:  Flow of fluid in which secondary irregular motions and veloc-
ity fluctuations are superimposed on the principal or average flow; in contrast
with laminar flow.

ULTIMATE ELONGATION:  The elongation of a stretched specimen at the time of
break.  Usually reported as percent of the original length.  Also called
elongation at break.

UNCONFINED COMPRESSIVE STRENGTH:   See "Compressive Strength."

UNCONSOLIDATED-UNDRAINED TEST (QUICK TEST):  A soil test in which the water
content of the test specimen remains practically unchanged during the applica-
tion of the confining pressure and the additional axial (or shear) force.

UNDERCONSOLIDATED SOIL DEPOSIT:   A deposit that is not fully consolidated
under the existing overburden pressure.

UNDESIRABLE SPECIES:  1.  Plant species that are not readily eaten by animals.
2.  Species that conflict with or do not contribute to the management
objectives.

UNDISTURBED SAMPLE:  A soil sample that has been obtained by methods in which
every precaution has been taken to minimize disturbance to the sample.

UNIFORMITY COEFFICIENT:  See "Coefficient of Uniformity."

UNIT WEIGHT OF WATER:  The weight per  unit volume of water; nominally equal to
62.4 pounds per cubic foot or 1 gram per cubic centimeter.

UNSATURATED FLOW:  The movement of water in a  soil which is not filled to
capacity with water.


                                     E-30

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UNSUPPORTED SHEETING:  A polymer sheeting one or more plies thick without a
reinforcing fabric layer or scrim.

VADOSE:  Pertaining to water in the unsaturated zone above the water table.

VANE SHEAR TEST:  An inplace shear test in which a rod with thin radial vanes
at the end is forced into the soil and the resistance to rotation of the rod
is determined.

VAPOR:  A gas below its critical point.

VAPOR PRESSURE:  Partial pressure of vapor (gaseous phase) of a substance in
equilibrium, at a given temperature, with a condensed phase (liquid or solid)
of the substance.

VARVED CLAY:  Alternating thin layers of silt (or fine sand) and clay formed
by variations in sedimentation during the various seasons of the year, often
exhibiting contrasting colors when partially dried.

VECTOR:  A carrier, e.g., an insect or a rodent, that is capable of transmit-
ting a pathogen from one organism to another.

VELOCITY HEAD:  Head possessed by an element of water by virtue of its
velocity.  Equal to  v2/2g  where v = velocity, g = acceleration of gravity.
Expressed in linear units (e.g.  feet).   In almost all seepage problems velocity
head is very small and is neglected.

VENT:  A hole or opening to permit passage or escape, as of a gas.

VISCOSITY GRADE (ASPHALT):   Viscosity classification for asphalt cement into
ranges specified in ASTM D3381.

VOID:  Space in a soil  mass not occupied by solid matter.  This space may be
occupied by air, water, or other gaseous or liquid material.

VOID RATIO:   The ratio of (1) the volume of void space to (2) the volume of
solid particles in a given soil  mass.

VOLUMETRIC SHRINKAGE (VOLUMETRIC CHANGE):   The decrease in volume of a soil
mass when the water content is reduced from a given percentage to the shrinkage
limit; expressed as a percentage of the volume of the soil mass when dried.

VULCANIZATE:   A term used to denote the product of the vulcanization of a
rubber compound without reference to shape or form.

VULCANIZATION:   An irreversible  process during which a rubber compound, through
a change in its chemical  structure, e.g.  crosslinking, becomes less plastic
and more resistant to swelling by organic liquids, and elastic properties are
conferred,  improved,  or extended over a greater range of temperature.

VULCANIZE:   See "Vulcanization."


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WARM-SEASON PLANT:   A plant that completes most of its growth during the warm
portion of the year, generally late spring and summer.

WATER CONTENT:  (Soil Mechanics) The ratio, expressed as a percentage,  of
(1) the weight of water in a given soil  mass to (2) the weight of solid parti-
cles.   (Soil Science) The amount of water lost from the soil  after drying it
to constant weight at 105°C, expressed either as the weight of water per unit
weight of dry soil  or as the volume of water per unit bulk volume of soil.

WATER TABLE:  The surface between the zone of saturation and the zone of
aeration; that surface of a body of unconfined ground water at which the
pressure is equal to that of the atmosphere.

WATER TABLE, PERCHED:  See "Perched Water Table."

WATERLOGGED:  Saturated with water; soil condition where a high or perched
water table is detrimental to plant growth, resulting from over-irrigation,
seepage, or inadequate drainage; the replacement of most of the soil air by
water.

WEED:   An undesired, uncultivated plant.

XEROPHYTE:  A plant capable of surviving periods of prolonged moisture
deficiency.

ZERO AIR VOIDS CURVE (SATURATION CURVE):  The curve showing the zero air voids
unit weight as a function of water content.
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                                  APPENDIX F

                             LAWS AND REGULATIONS
      The legislative and regulatory authority for remedial actions at uncon-
trolled hazardous waste sites resides in Public Law 96-510 (the "Superfund
Law") and the National Contingency Plan, as published in the Federal Register
on July 16, 1982 (Vol 47, No. 137, pp 31180-31243).

      For reference purposes, this appendix contains the following extracts
from these documents:

      - A Table of Contents of P.  L.  96-510
      - Table of Contents of the NCP
      - Text of Subpart F of the NCP, "Hazardous Substance Response"
      - Table of Contents of Appendix A to the NCP,  "Uncontrolled Hazardous
        Waste Site Ranking System"
                                      F-l

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Public Law 96-510
11  December 1980
96th Congress
             "COMPREHENSIVE ENVIRONMENTAL  RESPONSE,  COMPENSATION,
                          AND LIABILITY ACT OF  1980"
TITLE I - Hazardous Substances Releases,  Liability,  Compensation

Sec. 101.  Definitions
Sec. 102.  Reportable Quantities and Additional Designations
Sec. 103.  Notices, Penalties
Sec. 104.  Response Authorities
Sec. 105.  National Contingency Plan
Sec. 106.  Abatement Action
Sec. 107.  Liability
Sec. 108.  Financial Responsibility
Sec. 109.  Penalty
Sec. 110.  Employee Protection
Sec. 111.  Uses of Fund
Sec. 112.  Claims Procedure
Sec. 113.  Litigation, Jurisdiction, and Venue
Sec. 114.  Relationship to Other Law
Sec. 115.  Authority to Delegate, Issue Regulations

TITLE II - Hazardous Substance Response Revenue Act  of 1980

Sec. 201.  Short Title; Amendment of 1954 Code
Subtitle A - Imposition of Taxes on Petroleum and Certain Chemicals
Sec. 211.  Imposition of Taxes
Subtitle B - Establishment of Hazardous Substance Response Trust Fund
Sec. 221.  Establishment of Hazardous Substance Response Trust Fund
Sec. 222.  Liability of United States Limited to Amount in Trust Fund
Sec. 223.  Administrative Provisions
Subtitle C - Post-Closure Tax and Trust Fund
Sec. 231.  Imposition of Tax
Sec. 232.  Post-Closure Liability Trust Fund

TITLE III - Miscellaneous Provisions

Sec. 301.  Reports and Studies
Sec. 302.  Effective Dates, Savings Provision
Sec. 303.  Expiration, Sunset Provision
Sec. 304.  Conforming Amendments
Sec. 305.  Legislative Veto
Sec. 306.  Transportation
Sec. 307.  Assistant Administrator for Solid Waste
Sec. 308.  Separability
                                      F-2

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     31202         Federal  Register

Vol. 47,  No.  137, Friday,  July 16, 1982

        Rules and Regulations


     Part 1510, Title 40 of the Code of
   Federal Regulations is redqsignated as
   Part 300 in a new Subchapter J of
   chapter I and revised to read as follows:
   PART 300—NATIONAL OIL AND
   HAZARDOUS SUBSTANCES
   POLLUTION CONTINGENCY PLAN
   Subchapter J—Superfund Programs

   Subpart A—Introduction

   Sec.
   300.1  Purpose and objectives.
   300.2  Authority.
   300.3  Scope.
   300.4  Application.
   300.5  Abbreviations.
   300.6  Definitions.
   Subpart B—Responsibility
   300.21  Duties of President delegated to
       Federal agencies.
   300.22  Coordination among and by Federal
       agencies.
   300.23  Other assistance by Federal
       agencies.
   300.24  State and local participation.
   300.25  Non-government participation.
   Subpart C—Organization
   •300.31  Organizational concepts.
   300.32  Planning and coordination.
   300.33  Response operations.
   300.34  Special forces and teams.
   300.35  Multi-regional responses.
   300.36  Communications.
   300.37  Response equipment.
   Subpart D—Plans
   300.41  Regional and local plans.
   300.42  Regional contingency plans.
   300.43  Local contingency plans.
Subpart E—Operational Response Phases
for OH Removal
300.51  Phase I—Discovery and notification.
300.52  Phase II—Preliminary assessment
    and initiation of action.
300.53  Phase HI—Containment.
    countermeasures, clean-up and disposal.
300.54  Phase IV—Documentation and cost
    recovery.
300.55  General pattern of response.
300.56  Pollution reports.
300.57  Special considerations.
300.58  Funding.
Subpart F—Hazardous Substance
Response
300.61  General.
300.62  State role.
300.63  Phase I—Discovery and notification.
300.64  Phase II—Preliminary assessment
300.65  Phase III—Immediate removal.
300.66 Phase IV—Evaluation and
    determination of appropriate response—
    planned removal and remedial action.
300.67 Phase V—Planned removal.
300.68 Phase VI—Remedial action.
300.69 Phase VII—Documentation and cost
    recovery.
300.70 Methods of remedying releases.
300.71 Worker health and safety.

Subpart G—Trustees fdr Natural Resources
300.72  Designation of Federal trustees.
300.73  State trustees.
300.74  Responsibilities of trustees.
Subpart H—Use of Dispersants and Other
Chemicals
300.81  General.
Appendix A—Uncontrolled Hazardous
    Waste Site Ranking System; a users
    manual.
   Authority: Sec. 105, Pub. L. 96-510,94 Stat.
2764, 42 U.S.C. 9605 and sec. 311(c)(2). Pub. L
92-500, as amended; 86 Stat. 865, 33 U.S.C.
1321(c)(2): Executive Order 12316.47 FR 42237
 (August 20,1981); Executive Order 11735v38
 FR 21243 (August 1973).
                                                   F-3

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Subpart F—Hazardous Substance
Response

§300.61  General.
  (a) This subpart establishes methods
and criteria for determining the
appropriate extent of response
authorized by CERCLA when any
hazardous substance is released or there
is a substantial threat of such a release
into the environment, or there is a
release or substantial threat of a release
into the environment of any pollutant or
contaminant which may present an
imminent and substantial danger to the
public health or welfare.
  (b) Section 104(a](l) of CERCLA
authorizes removal or remedial action
unless it is determined that such
removal or remedial action will be done
properly by the owner or operator of the
vessel or facility from which the release
or threat of release emanates, or by any
other responsible party.
  (c) In determining the need for and in
planning or undertaking Fund-financed
action, response personnel should,  to the
extent practicable, consider the
following:
  (1) Encourage State participation in
response actions (see § 300.63).
  (2) Conserve Fund monies by
encouraging private party clean-up.
                 F-4

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31214
Federal Register / Vol. 47. No. 137,  Friday, July 16,  1982 / Rules and Regulations
  (3) Be sensitive to local community
concerns (in accordance with applicable
guidance).
  (4) Rely on established technology
when feasible and cost-effective.
  (5) Encourage the participation and
sharing of technology by industry and
other experts.

$300.62  State role.
  (a) States are encouraged to
undertake actions authorized under this
subpart. Section 104(d)(l) of CERCLA
authorizes EPA to enter into contracts or
cooperative agreements with the State
to take response actions authorized
under CERCLA, when EPA determines
that the State has the capability to
undertake such actions.
   (b) EPA will provide assistance from
the Fund to States pursuant to a contract
or cooperative agreement. The
agreement can authorize States to
undertake most actions specified in this
Subpart.
   (c)(l) Pursuant to section 104(c)(3) of
CERCLA, before any Fund-financed
remedial action may be taken, the
affected State(s) must enter into a
contract or cooperative agreement with
the Federal government
   (2) Included in such contract or
cooperative agreement must be
assurances by the State consistent with
requirements of section 104(c)(3) of
CERCLA.
   (d) Prior to remedial design activity,
the State must make a firm commitment
through either a cooperative agreement
or a new or amended State contract, to
provide funding for remedial
 implementation by:
   (1) Authorizing the reduction of a
 State credit to cover its share of costs;
   (2) Identifying currently available
 funds earmarked for remedial
 implementation: or
   (3) Submitting a plan with milestones
 for obtaining necessary funds.
   (e) State credits allowed under section
 104(c}{3) of CERCLA must be
 documented on a site-specific basis for
 State out-of pocket, non-Federal eligible
 response costs between January 1,1978,
 and December 11,1980. Prior to remedial
 investigation activity at a site, the State
 must submit its estimate of these costs
 as a part of the pre-application package
 when a cooperative agreement is used,
 or as a part of the State contract. State
 credits will be applied against State cost
 .shares for Federally-funded remedial
 actions. A State cannot be reimbursed
 from the Fund for credit in excess of its
 matching share.
   (f) Pursuant to section 104(c)(2) of
 CERCLA, prior to determining any
 appropriate remedial action, EPA shall
 consult with the affected State or States.
                         $ 300.63 Phase I—Discovery or
                         notification.
                           (a) A release may be discovered
                         through:
                           (1) Notification in accordance with
                         sections 103(a) or (c) of CERCLA;
                           (2) Investigation by government
                         authorities conducted in accordance
                         with section 104(e) of CERCLA or other
                         statutory authority;
                           (3) Notification of a release by a
                         Federal or State permit holder when
                         required by its permit;
                           (4) Inventory efforts or random or
                         incidental observation by government
                         agencies or the public;
                           (5) Other sources.
                           (b) If not reported previously, a
                         release should be promptly reported to
                         the NRG.  Section 103(a)  of CERCLA
                         requires any person in charge of a vessel
                         or facility to immediately notify the NRC
                         as soon as he has knowledge of a
                         release (other than a federally permitted
                         release) of a hazardous  substance from
                         such vessel or facility in an amount
                         equal to or greater than  the reportable
                         quantity determined pursuant to  section
                         102(b) of CERCLA. The NRC shall
                         convey the notification expeditiously to
                         appropriate government agencies, and in
                         the case of notices received pursuant to
                         section 103(a), the NRC  shall also notify
                         the Governor of any affected State.
                            (c) Upon receipt of a notification of a
                         release, the NRC shall promptly notify
                         the appropriate OSC.

                         § 300.64   Phase II—Preliminary
                         assessment
                            (a) A preliminary assessment of a
                          release identified for possible CERCLA
                          response  should be undertaken by the
                          lead agency. If the reported release
                          potentially requires immediate removal,
                          the preliminary assessment should be
                          done as promptly as possible. Other
                          releases shall be assessed as soon as
                          practicable. The lead  agency should
                          base its assessment on readily available
                          information. This assessment may
                          include:
                            (1) Evaluation of the magnitude of the
                          hazard;
                            (2) Identification of the source and
                          nature of the release;
                            (3) Determination of the existence of a
                          non-Federal party or parties ready,
                          willing, and able to undertake a proper
                          response; and
                            (4) Evaluation of factors necessary to
                          make the determination of whether
                          immediate removal is necessary.
                            (b) A preliminary assessment of
                          releases  from hazardous waste
                          management facilities may include
                          collection or review of data such as site
                          management practices,  information from
                          generators, photographs, analysis of
historical photographs, literature
searches, and personal interviews
conducted as appropriate. In additlo:
perimeter (off-site) inspection may be
necessary to determine the potential for
a release. Finally, if more information is
needed, a site visit may be performed, if
conditions are such that it may be
performed safely.
  (c) A preliminary assessment should
be terminated when the OSC
determines:
  (1) There is no release;
  (2) The source is neither a vessel nor a
facility;
  (3) The release involves neither a
hazardous substance, nor a pollutant or
contaminant that may pose an imminent
and substantial danger to public health
or welfare;
  (4) The amount released does not
warrant Federal response;
  (5) A party responsible for the release,
or any other person, is providing
appropriate response, and on-scene
monitoring by the government is not
recommended or approved by the lead
agency; or
  (6) The assessment is completed.

§ 300.65  Phase III—Immediate removal
  (a) In determining the appropriate
extent of action to be taken at a given
release, the lead agency shall first
review the preliminary assessment ti
determine if immediate removal action
is appropriate. Immediate removal
action shall be deemed appropriate in
those cases in which the lead agency
determines that the initiation of
immediate removal action will prevent
or mitigate immediate and significant
risk of harm to human life or health or to
the environment from such situations as:
   (1) Human, animal, or food chain
exposure to acutely toxic substances;
   (2) Contamination of a drinking water
 supply:
   (3) Fire and/or explosion; or
   (4) Similarly acute situations.
   (b) If the lead agency determines that
 immediate removal is appropriate,
 defensive actions should begin as soon
 as  possible to prevent or mitigate danger
 to the public health, welfare, or the
 environment. Actions may include, but
 are not limited to:
   (1) Collecting and analyzing samples
 to determine the source and dispersion
 of the hazardous substance and
 documenting those samples for possible
 evidentiary use.
   (2) Providing alternative water
 supplies.
   (3) Installing security fencing or other
 measures to limit access.
   (4) Controlling the source of release.
   (5) Measuring and sampling.
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              Federal Register  /  Vol. 47.  No. 137, Friday. July 16. 1982  / Rules and Regulations	31215
  (6] Moving hazardous substances off-
site for storage, destruction, treatment.
or disposal provided that the substances
are moved to a facility that is in
compliance with subtitle C of the Solid
Waste Disposal Act, as amended by the
Resource Conservation and Recovery
Act.
  (7) Placing physical barriers to deter
the spread of the release.
  (8) Controlling the water discharge
from an upstream impoundment.
  (9) Recommending to appropriate
authorities the evacuation of threatened
individuals.
  (10 Using chemicals and other
materials in accordance with Subpart H
to restrain the spread of the substance
and to mitigate its effects.
  (11] Executing damage control or
salvage operations.
  (c) Immediate removal actions are
complete when, in the opinion of the
lead agency, the criteria in subsection
(a) of § 300.65 are no longer met and any
contaminated waste materials
transported off-site have been treated or
disposed of properly.
   (d) Immediate removal action shall be
terminated after $1  million has been
obligated for the action or six months
have elapsed from the date of initial
response to a release or threatened
release unless it is determined that:
   (1) Continued response actions are
immediately required to prevent, limit or
 mitigate an emergency;
   (2) There is an immediate risk to
 public health or welfare or the
 environment; and
   (3) Such assistance will not otherwise
 be provided on a timely basis.
   (e) If the lead agency determines that
 the release still may require planned
 removal or remedial action, the lead
 agency or a State may initiate, either
 simultaneously or sequentially. Phase IV
 or V as appropriate.

 § 300.66  Phase IV—Evaluation and
 determination of appropriate response-
 planned removal and remedial action.
    (a) The purpose of this phase is to
 determine the appropriate action when
 the preliminary assessment indicates
 that further response may be necessary
 or when the OSC requests and the lead
 agency concurs that further response
 should follow an immediate removal
 action.
    (b) As soon as practicable, an
 inspection will be undertaken to assess
 the nature and extent of the release and
 to assist in determining its priority for
 Fund-financed response.
    (c)(l) Pursuant to section 104 (b) and
 (e) of CERCLA. the responsible official
 may undertake investigations,
 monitoring, surveys, testing and other
Information gathering as appropriate.
These efforts shall be undertaken jointly
by the Federal or State officials
responsible for providing Fund-financed
response and those responsible for
enforcing legal requirements.
  (2) A major objective of an inspection
is to determine if there is any immediate
danger to persons living or working near
the facility. In general, the collection of
samples should be minimized during
inspection activities; however,
situations in which there is an apparent
risk to the public should be treated as
exceptions to that practice. Examples of
apparent risk include use of nearby
wells for drinking water, citizen
complaints of unusual taste or odor in
drinking water, or chemical odors or
unusual health problems in the vicinity
of the release. Under those
circumstances, a sampling protocol
should'be developed for the inspection
to allow for the earliest possible
detection of any human exposure to
hazardous substances. The site
inspection may also address:
   (i) Determining the need for
immediate removal action;
   (ii) Assessing amounts, types and
location of hazardous substances stored;
   (iii) Assessing potential for
 substances  to migrate from areas where
 they were originally located;
   (iv) Determining or documenting
 immediate threats to the public or
 environment.
   (d) Methods for Establishing
 Priorities. (1) States that wish to submit
 candidates  for the National Priorities
 List must use the Hazard Ranking
 System (included in Appendix A) to
 rank the releases.
   (2) EPA will notify States at least
 thirty days  prior to the deadline  for
 submitting candidate releases for the
 National Priorities List or any
 subsequent revisions.
   (3) Each State may designate a facility
 as the State's highest priority release by
 certifying, in writing signed by the
 Governor or the Governor's designee,
 that the facility presents the greatest
 danger to public health, welfare  or the
 environment.among known facilities in
 the State.
   (e) National Priorities List. (1)
 Compiling the National Priorities List—
 EPA Regional Office will review State
 hazard rankings to ensure uniform
 application of the Hazard Ranking
 System and may add, in consultation
  with the States, any additional priority
  releases known to EPA. The States'
  priorities will be reviewed and
  consolidated by EPA Headquarters into
  a National Priorities List pursuant to
  section 105(8) of CERCLA. To the extent
  practicable, each State's designated top
priority facility will be included among
the one hundred highest priority
facilities.
  (2) No facilities presently owned by
the Federal Government will be
included on the National Priorities List.
  (3) EPA will submit the recommended
National Priorities  List to the NRT for
review and comment.
  (4) EPA will publish a proposed
National Priorities  List for public
comment.
  (5) The National Priorities List is
presented in Appendix B.
  (6) Ranking of Releases—Similar
hazard ranking scores assigned  to
releases cannot accurately differentiate
among risks represented by the  releases.
Thus, in order to avoid misleading the
public that real differences in risk exist,
similar scores may be grouped on the
National Priorities List.
   (7) EPA will revise and publish the
National Priorities List at least once
annually. In addition, revisions  will give
notice of the deletion (if any] of releases
previously listed.

§ 300.67  Phase V—Planned removal.
   (a] Planned removal may be
undertaken pursuant to a contract or
 cooperative agreement when the lead
 agency determines that:
   (1) There would be a substantial cost
 savings by continuing a response action
 with the equipment and resources
 mobilized for an immediate removal
 action taken pursuant to § 300.64, but
 terminate pursuant to § 300.64(c); or
   (2) The public and/or environment
 will be at risk from exposure to
 hazardous substances if response is
 delayed at a release not  on the National
 Priorities List.
   (b) Planned removal must be
 requested by the Governor of the
 affected State or his designee. Requests
 must include:
   (1) A description of the nature and
 extent of the release;
   (2] A description of actions taken or
 underway at the site;
   (3) A description of the proposed
 planned removal; and
   (4] Assurances  that the State will pay
  at least 10 percent of the costs  of the
  action, including all future maintenance,
  or at least 50 percent or such greater
  amount as EPA may determine
  appropriate, taking into  account the
  degree of responsibility  of the State or
  political subdivision, of any sums
  expended in response to a release at a
  facility that was owned at the  time of
  any disposal of hazardous substances
  therein by the State or a political
  subdivision thereof.
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  (c) Among the factors that EPA will
use to determine whether a planned
removal is appropriate under
§ 300.67(a)(2) are the following:
  (1) Actual or potential direct contact
with hazardous substances by nearby
population:
  (2) Contaminated drinking water at
the tap:
  (3) Hazardous substances in drums,
barrels, tanks, or other bulk storage
containers, that are known to  pose a
serious threat to public health or the
environment;
  (4) Highly contaminated soils largely
at or near surface, posing a serious
threat to public health or the
environment;
  (5) Serious  threat of fire or explosion;
or
  (6) Weather conditions that may
cause substances to migrate and pose a
serious threat to public health or the
environment
  (d) Planned removal actions shall be
terminated when the lead agency
determines that the risk to the public
health or the  environment has been
abated. In making this determination,
the lead agency shall consider whether
the factors listed in § 300.66(c) continue
to apply to the release and whether any
contaminated waste materials
transported off-site have been treated or
disposed of properly.
  (e) Unless the EPA finds that (1)
continued response actions are
immediately required to prevent, limit or
mitigate an emergency, (2) there is an
immediate risk to public health or
welfare or the environment, and (3) such
assistance will not otherwise  be
provided on a timely basis, obligations
from the Fund, other than those
authorized by section I04(b) of
CERCLA. shall not continue after $1
million has been obligated for response
actions or six months has elapsed from
the date of initial response to  the
release.

§300.68  Phase VI—Remedial action.
  (a) Remedial actions taken pursuant
to this section (other than responses at
Federal facilities) are those responses to
releases on Ine National Priorities List
that are consistent with permanent
remedy to prevent or mitigate the
migration of a release of hazardous
substances into the. environment
  (b) States are encouraged to
undertake Fund-financed remedial
actions in accordance with §.300.62 of
this Plan.
  (c) As an alternative or in addition to
Fund-financed remedial action, the lead
agency may seek, through voluntary
agreement or administrative or judicial
process, to have those persons
                         responsible for the release clean up in a
                         manner that effectively mitigates and
                         minimizes damage to, and provides
                         adequate protection of, public health,
                         welfare, and the environment. The lead
                         agency shall evaluate the adequacy of
                         clean-up proposals submitted by
                         responsible parties or determine the
                         level of clean-up to be sought through
                         enforcement efforts, by consideration of
                         the factors discussed in paragraphs (e)
                         through (j) of this section. The lead
                         agency will not, however, apply the cost
                         balancing considerations discussed in
                         paragraph (k) of this section to
                         determine the appropriate extent of
                         responsible party clean-up.
                           (d)(l) The lead agency, in cooperation
                         with State(s), will examine available
                         information  and determine, based  on the
                         factors in  paragraph (g) of this section,
                         the type or types of remedial response
                         that may be  needed to remedy the
                         release. This scoping will serve as the
                         basis for requesting funding for a
                         remedial investigation and feasibility
                         study:
                           (i) In the case of initial remedial
                         measures, a  single request may be made
                         by a State for funding the remedial
                         investigation, feasibility study, design
                         and implementation, in order that such
                         measures  may be expedited while
                         continuing the remainder of the remedial
                         planning process.
                           (ii) In the case of source control or off-
                         site remedial action-, the initial funding
                         request should be for the remedial
                         investigation and feasibility study.
                         Requests for funding of design and
                         implementation should be made after
                         the completion of the feasibility study.
                           (2) As a remedial investigation
                         progresses, the project may be modified
                         if the lead agency determines that,
                         based on the factors in 300.68(e), such
                         modifications would be appropriate.
                           (e) In determining the appropriate
                         extent of remedial action, the following
                         factors should be used to determine the
                         type or. types of remedial action that
                         may be appropriate:
                           (1) In some instances, initial remedial
                         measures  can and should begin before
                         final selection of an appropriate
                         remedial action if such measures are
                         determined to be feasible and necessary
                         to limit exposure or threat of exposure
                         to a significant health or environmental
                         hazard and if such measures are cost-
                         effective. Compliance with § 300.67(b) is
                         a prerequisite to taking initial remedial
                         measures. The following factors should
                         be used in determining whether initial
                         remedial measures are appropriate:
                           (i) Actual or potential direct contact
                         with hazardous substances by nearby
                         population. (Measures might include
                         fences and other security precautions.)
  (ii) Absence of an effective drainage
control system (with an emphasis on
run-on control). (Measures might incluv
drainage ditches.)
  (iii) Contaminated drinking water at
the tap. (Measures might include the
temporary provision of an alternative
water supply.)
  (iv) Hazardous substances in drums,
barrels, tanks, or other bulk storage
containers, above surface posing a
serious threat to public health or the
environment. (Measures might include
transport of drums off-site.)
  (v) Highly contaminated soils  largely
at or near surface, posing a serious
threat to public health or the
environment. (Measures might include
temporary capping or removal of highly
contaminated soils from drainage
areas.)
  (vi) Serious threat of fire or explosion
or other serious threat to public  health
or the environment. (Measures might
include security or drum removal.)
  (vii) Weather conditions that may
cause substances to migrate and to  pose
a serious threat to public health  or the
environment. (Measures might include
stabilization of berms, dikes or
impoundments.)
  (2) Source control remedial actions
may be appropriate if a substantial
concentration of hazardous substances
remain at or near the area where they
were originally located and inadequate
barriers exist to retard migration of
substances into the environment. Source
control remedial actions may not be
appropriate if most substances have
migrated from the area where originally
located or if the lead agency determines
that the substances are adequately
contained. Source control remedial
actions may include alternatives to
contain the hazardous substances where
they are located or eliminate potential
contamination by transporting the
hazardous substances to a new location.
The following criteria should be
assessed in determining whether and
what type of source control remedial
actions should be considered:
  (i) The extent to which substances
pose a danger to public health, welfare,
or the environment. Factors which
should be considered in assessing this
danger include:
  (A) Population at risk;
  (B) Amount and form of the substance
present;
  (C) Hazardous properties of the
substances;
  (D) Hydrogeological factors (e.g. soil
permeability depth to saturated zone,
hydrologic gradients, proximity to a
drinking water aquifer); and
  (E) Climate (rainfall, etc.).
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  (ii) The extent to which substances
have migrated or are contained by either
natural or man-made barriers.
  (Hi) The experiences and approaches
used in similar situations by State and
Federal agencies and private parties.
  (iv) Environmental effects and welfare
concerns.
  (3) In some situations it may be
appropriate to take action (referred to as
offsite remedial actions) to minimize
and mitigate the migration of hazardous
substances and the effects of such
migration. These actions may be taken
when the lead agency determines that
source control remedial actions may not
effectively mitigate and-minimize the
threat and there is a significant  threat to
public health, welfare, or the
environment. These situations typically
will result from contamination that has
migrated beyond the area where the
hazardous substances were originally
located. Offsite measures may include
provision of permanent alternative
water supplies, management of a
drinking water aquifer plume or
treatment of drinking water aquifers.
The following criteria should be used in
determining whether and what type  of
offsite remedial actions should be
considered:
  (i) Contribution of the contamination
to an air, land or water pollution
problem.
  (ii) The extent to which the
substances have migrated or are
expected to migrate from the area of
their original location and whether
continued migration may pose a danger
to public health, welfare or environment.
  (iii) The extent to which natural or
man-made  barriers currently contain the
hazardous  substances and the adequacy
of the barriers.
  (iv) The factors listed in paragraph
(e)(2)(i) of this section.
  (v) The experiences and approaches
used  in similar situations by State and
Federal agencies and private parties.
  (iv) Environmental effects and welfare
concerns.
  (f) A remedial investigation should be
undertaken by the lead agency (or
responsible party if the responsible
party will be developing a clean-up
proposal) to determine the nature and
extent of the  problem presented by the
release. This includes sampling and
monitoring, as necessary, and includes
the gathering of sufficient information to
determine the necessity for and
proposed extent of remedial action.
During the  remedial investigation, the
original scoping of the project may be
modified based on the factors in
§ 300.68(e). Part of the remedial
investigation involves assessing
whether the threat can be mitigated and
minimized by controlling the source of
the contamination at or near the area
where the hazardous substances were
originally located (source control
remedial actions) or whether additional
actions will be necessary because the
hazardous substances have migrated
from the area of their original location
(offsite remedial actions).
  (g) Development of Alternatives. A
limited number of alternatives should be
developed for either source control or
offsite remedial actions (or both)
depending upon the type of response
that has been identified under
paragraphs (e) and (f)  of this section as
being appropriate. One alternative may
be a no-action alternative. No-action
alternatives are appropriate, for
example, when response action may
cause a greater environmental or health
danger than no action. These
alternatives should be developed based
upon the assessment conducted under
paragraphs (e) and (f)  of this section and
reflect the types of source control or
offsite remedial actions determined to
be appropriate under paragraphs (e) and
(f) of this section.
  (h) Initial Screening of Alternatives,
The alternatives developed under
paragraph (g) of this section will be
subjected to an initial screening to
narrow the list of potential remedial
actions for further detailed analysis.
Three broad criteria should be used in
the initial screening of alternatives:
  (1) Cost. For each alternative, the cost
of installing or implementing the
remedial action must be considered,
including operation and maintenance
costs. An alternative that far exceeds
(e.g. by an order of magnitude) the costs
of other alternatives evaluated and that
does not provide substantially greater
public health or environmental benefit
should usually be excluded from further
consideration.
  (2) Effects of the Alternative. The
effects of each alternative should be
evaluated in two ways: (i) Whether the
alternative itself or its implementation
has any adverse environmental effects;
and (ii) for source control remedial
actions, whether the alternative is likely
to achieve adequate control of source
material, or for offside remedial actions,
whether the alternative is likely to
effectively mitigate and minimize the
threat of harm to public health, welfare
or the environment. If an alternative has
significant adverse effects, it should be
excluded from further consideration.
Only those alternatives that effectively
contribute to protection of public health,
welfare, or the  environment should be
considered further.
   (3) Acceptable Engineering Practices.
Alternatives must be feasible for the
location and conditions of the release,
applicable to the problem, and represent
a reliable means of addressing the
problem.
  (i) Detailed Analysis of Alternatives.
  (1) A more detailed evaluation will be
conducted of the limited number of
alternatives that remain after the initial
screening in paragraph (h).
  (2) The detailed analysis of each
alternative should include:
  (A) Refinement and specification ot
alternatives in detail, with emphasis nn
use of established technology;
  (B)  Detailed cost estimation, including
distribution of costs over time;
  (C) Evaluation in terms of engineering
implementation, or constructability;
  (D) An assessment of each alternative
in terms  of the extent to which it is
expected to effectively mitigate and
minimize damage to, and provide
adequate protection of, public health,
welfare,  and the environment, relative to
the other alternatives analyzed; and
  (E) An analysis of any adverse
environmental impacts, methods for
mitigating these impacts, and costs of
mitigation.
  (3)  In performing the detailed analysis
of alternatives, it may be necessary to
gather additional data in order to
complete the analysis,
  (j) The appropriate extent of remedy
shall  be  determined by the lead agency's
selection of the remedial alternative
which the agency determines is cost-
effective (i.e. the lowest cost alternative
that is technologically feasible and
reliable and which effectively mitigates
and minimizes damage to and provides
adequate protection  of public health.
welfare,  or the environment).
  (k) Section 104(c)(4) of CERCLA
requires  that the need for protection of
public health, welfare and the
environment at the facility under
consideration be balanced against the
amount of money available in the Fund
to respond to other sites which present
or may present a threat to public health
or welfare or the environment, taking
into consideration the need for
immediate action. Accordingly,  in
determining the appropriate extent of
remedy for Fund-financed response, the
lead agency also must consider the need
to respond to other releases with Fund
monies.

§ 300.69  Phase VII—Documentation and
cost recovery,
  (a) During all phases,  documentation
shall be  collected and maintained to
support  all actions taken under this
Plan, and to form the basis for cost
recovery. In general, documentation
should be sufficient to provide the
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source and circumstances of the
condition, the identity of responsible
parties, accurate accounting of Federal
costs incurred, and impacts and
potential impacts to the public health,
welfare and environment.
  (b) The information and reports
obtained by the lead agency for Fund-
financed response action should be
transmitted to the RRC. Copies can then
be forwarded to the NRT, members of
the RRT, and others as appropriate.

1300.70  Methods of remedying releases.
  (a) The following section lists
methods for remedying releases that
may be considered by the lead agency in
taking response action. This list of
methods should not be considered
inclusive of all possible methods of
remedying releases.
  (b) Engineering Methods for On-Site
Actions.—(l](i) Air emissions control—
The control of volatile gaseous
compounds should address both lateral
movement and atmospheric emissions.
Before gas migration controls can be
properly installed, field measurements
to determine gas concentrations,
pressures, and soil permeabilities should
be used to establish optimum design for
control. In addition, the types  of
hazardous  substances present, the depth
to which they extend, the nature of the
gas and the subsurface geology of the
release area should, if possible, be
determined. Typical emission  control
techniques include the following:
  (A) Pipe vents:
  (B) Trench vents;
  (C) Gas barriers;
  (D) Gas collection systems;
  (E) Overpacking.
  (iij Surface water controls—These are
remedial techniques designed to reduce
waste infiltration and to control runoff
at release areas. They also serve to
reduce erosion and to stabilize the
surface of covered sites. These types of
control technologies are usually
implemented in conjunction with other
types of controls such as the elimination
of ground water infiltration and/or
waste stabilization, etc. Technologies
applicable to surface water control
include the following:
  (A) Surface seals;
  (B) Surface water diversion  and
collection systems:
  [1] Dikes and berms;
  [2] Ditches, diversions, waterways;
  (3) Chutes and downpipes;
  (4) Levees;
  (5) Seepage basins and ditches;
  (6} Sedimentation basins and ponds;
  (7) Terraces and benches,
  (C) Grading;
  (D) Revegetation.
                           (iii) Ground water controls—Ground
                         water pollution is a particularly serious
                         problem because, once an aquifer has
                         been contaminated, the resource cannot
                         usually be cleaned without the
                         expenditure of great time, effort and
                         resources. Techniques that can be
                         applied to the problem with varying
                         degrees of success are as follows:
                           (A) Impermeable barriers:
                           U) Slurry walls;
                           (2) Grout curtains;
                           (3) Sheet pilings.
                           (B) Permeable treatment beds;
                           (C) Ground water pumping:
                           [1] Water table adjustment;
                           (2) Plume containment.
                           (D) Leachate control—Leachate
                         control systems are applicable to control
                         of surface seeps and seepage of leachate
                         to ground water. Leachate collection
                         systems consist of a series of drains
                         which intercept the leachate and
                         channel it to a sump, wetwell, treatment
                         system, or appropriate surface discharge
                         point. Technologies applicable to
                         leachate control include the following:
                           (1) Subsurface drains;
                           [2] Drainage ditches;
                           (3] Liners.
                           (iv) Contaminated water and sewer
                         lines—Sanitary sewers and municipal
                         water mains located down gradient from
                         hazardous waste disposal sites may
                         become contaminated by infiltration of
                         leachate or polluted ground water
                         through cracks, ruptures, or poorly
                         sealed joints in piping. Technologies
                         applicable to the control of such
                         contamination to water and sewer lines
                         include:
                           (A) Grouting;
                           (B) Pipe relining and sleeving;
                           (C) Sewer relocation.
                           (2) Treatment technologies, (i)
                         Caseous emissions treatment—Gases
                         from waste disposal sites frequently
                         contain malodorous and toxic
                         substances, and thus require treatment
                         before release to the atmosphere. There
                         are two basic types of gas treatment
                         systems:
                           (A) Vapor phase adsorption;
                           (B) Thermal oxidation.
                           (iij Direct waste treatment methods—
                         In most cases, these techniques can be
                         considered long-term permanent
                         solutions. Many of these direct
                         treatment methods are not fully
                         developed and the applications and
                         process reliability are not well
                         demonstrated. Use of these techniques
                         for waste treatment may require
                         considerable pilot plant work.
                         Technologies applicable to the direct
                         treatment of wastes are:
                           (A) Biological methods:

                                          F-9
   [1] Treatment via modified
conventional wastewater treatment
techniques;
   (2) Anaerobic, aerated and facultative
lagoons;
   (3) Supported growth biological
reactors.
   (B) Chemical methods:
   (1) Chlorination;
   [2] Precipitation, flocculation,
sedimentation;
   (3) Neutralization;
   (4) Equalization;
   (5) Chemical oxidation.
   (C) Physical methods:
   (1} Air stripping;
   (2) Carbon absorption;
   (3) Ion exchange;
   (4} Reverse osmosis;
   (5) Permeable bed treatment;
   [6] Wet air oxidation;
   (7) Incineration.
   (iii) Contaminated soils and
sediments—In some cases where it can
be shown to be cost-effective,
contaminated sediments and soils will
be treated on the site. Technologies
available include:
   (A) Incineration;
   (B) Wet air oxidation;
   (C) Solidification;
   (D) Encapsulation;
   (E) In situ treatment:
   (1) Solution mining, (soil washing or
soil flushing);
   [2] Neutralization/detoxification;
   (3} Microbiological degradation.
   (c) Off site Transport for Storage,
Treatment, Destruction or Secure
Disposition.—{1} General—Offsite
transport  or storage, treatment,
destruction, or secure disposition offsite
may be provided in cases where EPA
determines that such actions:
   (i) Are more cost-effective than other
forms of remedial actions;
   (ii) Will create new capacity to
manage, in compliance with Subtitle C
of the Solid Waste Disposal Act,
hazardous substances in addition to
those located at the affected facility; or
   (iii) Are necessary to protect public
health, welfare, or the environment from
a present or potential risk which may be
created by further exposure to the
continued presence of such substances
or materials.
   (2) Contaminated soils and sediments
may be removed from the site.
Technologies used to remove
contaminated sediments on soils
include:
  (i) Excavation;
  (ii) Hydraulic dredging;
  (iii) Mechanical dredging.
  (d) Provision of Alternative Water
Supplies—Alternative water supplies
can be provided in several ways:

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  (1) Provision of individual treatment
units;
  (2) Provision of water distribution
system;
  (3) Provision of new wells in a new
location or deeper wells;
  (4) Provision of cisterns;
  (5) Provision of bottled or treated
water,
  (6) Provision of upgraded treatment
for existing distribution systems.
  (e) Relocation—Permanent relocation
of residents, businesses, and community
facilities may be provided where it is
determined that human health is in
danger and that, alone or in combination
with other measures, relocation would
be cost-effective and environmentally
preferable to other remedial response.
Temporary relocation may also be taken
in appropriate circumstances.

§ 300.71  Worker health and safety.
  Lead agency personnel should be
aware of hazards, due to a release of
hazardous substances, to human health
and safety and exercise great caution iu
allowing civilian or government
personnel into an affected area until the
nature of the release has been
ascertained. Accordingly, the OSC or
responsible official must conform to
applicable OSHA requirements and
other guidance. All private contractors
who are working at the scene of a
release must conform to applicable
provisions of the Occupational Safety
and Health Act and any other
requirements deemed necessary by the
lead agency.
Appendix A—Uncontrolled Hazardous Waste
Site Ranking Sustem; A Users Manual

Table of Contents
List of Illustrations OList of Tables
1.0  Introduction
2.0  Using the Hazard Ranking System—
    General Considerations
3.0  Ground Water Migration Route
3.1  Observed Release
3.2  Route Characteristics
3.3  Containment
3.4  Waste Characteristics
3.5  Targets
4.0  Surface Water Route
4.1  Observed Release
4.2  Route Characteristics
4.3  Containment
4.4  Waste Characteristics
4.5  Targets
5.0  Air Route
5.1  Observed Release
5.2  Waste Characteristics
5.3  Targets
6.0  Computing the Migration Hazard Mode
    Score.  SM
7.0  Fire and Explosion
7.1  Containment
7.2  Waste Characteristics
7.3  Targets
8.0  Direct Contact
8.1  Observed Incident
8.2  Accessibility
8.3  Containment
8.4  Waste Characteristics
8.5  Targets
                                             F-10

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                                   APPENDIX G

                          QUALITY-CONTROL TEST METHODS



The  following test methods are described in this Appendix.
Method
Water Content
Standard Oven-Dry*
Standard Nuclear Moisture/Density Gage*
Gas Burner
Alcohol Burning
Calcium Carbide (Speedy)
Microwave Oven
Infrared Oven
Unit Weight
Standard Laboratory Volumetric
Standard Laboratory Displacement
Standard Field Sand-Cone
Standard Field Rubber Balloon
Standard Field Drive-Cylinder
Standard Nuclear Moisture/Density Gage
Specific Gravity
Standard Laboratory
Grain-Size Distribution
Standard Sieve Analysis (+200 Fraction)
Amount of Soil Finer than No. 200 Screen (Wash) Standard
Standard Laboratory Hydrometer ((-200 Fraction)
Pipette Method for Silt and Clay Fraction
Decantation Method for Silt and Clay Fraction

Liquid Limit
Standard Multipoint*
Standard One Point
Plastic Limit
Standard Laboratory*
Number

1
2
3
4
5
6
7

8
9
10
11
12
13

14

15
16
17
18
19


20
21

22
Method
Consistency (Cohesive Soil)
Standard Unconfined Compression*
Field Expedient Unconfined Compression
Hand Penetrometer*
Handheld Torvane
Water Content/Densi ty/Compactive Effort
25 Blow Standard Proctor Compaction*
25 Blow Modified Proctor Compaction*
Rapid, One Point Proctor Compaction
Rapid, Two Point Proctor Compaction*
Hilf's Rapid
Ohio Highway Department Nest of Curves
Harvard Miniature Compaction
Relative Density (Cohesionless Soil)
Standard Laboratory Maximum Density*
Standard Laboratory Minimum Density*
Modified Providence
Geomembrane/Geotextile Seam Integrity

Bonded Seam Strength*
Breaking Strength*
Peel Adhesion*
Air Lance
Vacuum Box*
Conductivity
Ultrasonic



Number

23
24
25
26

?7
28
29
30
31
32
33
34

35
36
37

38
39
40
41
42
43
44



 Generally recommended or preferred method.
     These descriptions are  brief  and  are presented primarily for information
purposes.  Wherever a reference  is given, that reference should be consulted
for directors as to the actual conduct of the test.   Test data sheets are in-
cluded as illustrative examples  with many of the test methods given.  All of
these sample data sheets came  from actual construction sites where they were
in use.   They should not be  regarded as specifically recommended forms, how-
ever, as they contain some inconsistencies and omissions of desirable data.
They are included for purposes of  illustration only.

                                       G-l

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                                                                  Method No.  1

Parameter Measured:   Water Content

Title of Test Method:   Standard Oven-Dry

Principle of Test Method:   This method determines the water content of a soil
sample by first weighing it wet and then again after it has been dried in
an oven.

Test Method

     (1)  Apparatus:   Drying oven (thermostatically controlled, preferably
of the force-draft type),  balance sensitive to 0.01 g. , specimen containers
(tares) with lids, and a desiccator.

     (2)  Procedure:   The procedure for this method consists simply of taking
a specimen of known weight, placing it into an oven and drying it at a partic-
ular temperature and specified time.   Upon drying the specimen is removed,
reweighed and the moisture content is calculated.

     (3)  Reference:   ASTM D 2216.

Limitations:  With many soils, close control of water content during field
compaction is necessary to develop a required density, strength and hydraulic
conductivity in the soil mass.  Oven-drying is the standard test for deter-
mining water content of soils in geotechnical engineering practice.  However,
the method does not lend itself easily to field use.  Although temperature
controlled ovens are currently available on some construction sites, they
require 4 to 12 hours for drying which may be excessive for close control
of field compaction.   All  soils can be tested for moisture content by
oven-drying.

Status of the Method:  Oven-drying of soil is the accepted laboratory method
among the geotechnical engineering profession for determination of water
content.

Calibration Procedure:  N/A

Documentation of Test:  Items to be recorded include the wet weight and the
dry weight.  An example data  sheet is provided.
                                      G-2

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Name:.

Date:_
.Saaple Nunbera.

. Sheet Number _
'fATER CONTENT DETERMINATIONS
DATA AND COiCPUTATIOH SHEET


NOTES:   Tare Is weight of container (watch glasses and clip. Petrl dishes, can. etc.)
        Water Content = w= ffti of
                                        -
                            Wt. of Dry Soil
                                               100*
Saraple Nuaber
Type o? Test
Container Nuaber
Wt. Sample •*• Tare Wet
Wt. Sample + Tare Dry
Wt. of Water
Tare
Wt. of Dry Soil
Water Content






















































Sample Number
Type of Test
Container Number
Wt. Sample + Tare Wet
Wt. Sc=ple + Tare Dry
Wt. of Water
Tare
Wt. of Dry Soil
Water Content






















































Sample Number
Type of Test
Container Number
Wt. Sample + Tare Wet
Wt. Sample ••• Tare Dry
Wt. of Water
Tare
Wt. of Dry Soil
Water Content






















































                                           G-3

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                                                                  Method No. 2

Parameter Measured:   Water Content

Title of Test Method:  Standard Nuclear Moisture/Density Gage

Principle of Test Method:  This method measures in-place water content by
directing fast neutrons of known intensity into the soil and measuring the
intensity of slow or moderated neutrons reflected back.

Test Method

     (1)  Apparatus:  Fast neutron source, slow neutron detector (readout
device and housing)  and reference standard and site preparation device.

     (2)  Procedure:  This method allows the determination of water content
of soil and soil  aggregate in place through the use of nuclear equipment.
The equipment is  calibrated to determine water content,  as weight of water
per unit volume of material.   Water content as normally used is defined
as the ratio, expressed as a percentage, of the weight of water in a given
soil mass to the  weight of solid particles.  It is determined with this
procedure by dividing the water content by the dry unit weight of the
soil.   Therefore, computation of water content using the nuclear equip-
ment also requires the determination of the dry unit weight of the material
being tested.  Most available nuclear equipment has the provision for mea-
suring both the water content and the wet unit weight.  The difference between
these two measurements gives the dry unit weight.   Recent units give a direct
readout of water  content and dry unit weight.   Some can be set to yield per-
cent compaction.

     (3)  Reference:  ASTM D 3017.

Limitations:  The method described is useful as a rapid, nondestructive
technique for the in-place determination of the water content of soil.  The
fundamental assumptions inherent in the method are that the hydrogen present
is in the form of water as defined by ASTM D 2216, and that the material under
test is homogeneous.  Test results may be affected by chemical composition,
sample heterogeneity, and, to a lesser degree, material  density and the
surface texture of the material being tested.   The technique also exhibits
spatial bias in that the apparatus is more sensitive to certain regions of the
material under test.  The nuclear method, which is applicable to a wide range
of soils, requires operation by an experienced technician in order to obtain
reliable measurements.  A weakness in the nuclear method is that a sample is
not taken to determine the water content, and thus the test results cannot be
compared to the other water content methods, e.g.  the oven-dry method.   In
addition, this method requires equipment that utilizes radioactive materials
which themselves  may be hazardous to the health of the operator.  Effective
operator instructions together with routine safety procedures are essential to
the proper operation of this type of equipment.

Status of the Method:  Nuclear gages offer a rapid and accurate means for
obtaining water content values for a wide variety of soils.  Recent advances

                                      G-4

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in the design of nuclear equipment and a better understanding of the nuclear
principles involved have led to increasingly widespread use of nuclear gages
in earthwork construction control.

Calibration Procedure:   The apparatus must be calibrated against a reliable
direct method (e.g.  oven-drying).

Documentation of Test:   Items to be recorded include the water content
and the wet unit weight.   An example data sheet is provided.
                                      G-5

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A
3

Moisture Standard Count |
Density Standard Count }
DATA SHEET FOP, FIELD DENSITY TEST
NUCLEAR. GAUGE MET HOD
Gauge Typa

j Serial NOI
FOR |
008
MATERIAL
TEST LOCATION
ELEVATION
TEST NUMBER
C
D
L
>
G
•H
1
J
K
L
M
N
0
P
Q
R
Moisture Count
Moisture Count Ratio
Density Count
Air-Gap Count (if used)
Density Count Ratio
Density, Wet Wt. , PCF
Moisture Content, PCF
Density, Dry Wt. , PCF
MOISTURE CONTENT, PERCENT
OPTIMUM MOISTURE, PERCENT
DENSITY, DRY WT., PCF
THEORETICAL DENSITY, PCF
PERCENT COMPACTION
REQUIRED PERCENT COMPAC.
MODE & PROBE DEPTH, IN.
TYPE OF MATERIAL
v
/ \


/ \l

C
A"


~1 E
B or F"
From G
& Chart
From D
& Chart
H - I
I
J
See Curve
From J
See Curve
$ x TOO
See Specs.


Laboratory No.
























003 NO.
DATE












I







1
















1


I '
I '
i
j


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i
Technician(s)
G-6

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                                                                  Method No.  3

Parameter Measured:   Water Content

Title of Test Method:  Gas Burner

Principle of Test Method:   This method determines the water content of a soil
sample by first weighing it wet and then again after it has been dried.

Test Method

     (1)  Apparatus:   Gas stove, frying pan, balance and stirring rods.

     (2)  Procedure:   This method covers determination of the approximate
moisture content of soils by means of a gas-burner stove, in field control
of earthwork.  The gas burner method involves the weighing of a moist sample,
placing the sample in a pan on the stove and drying to constant weight, with
occasional stirring of the sample to prevent burning.  The dry sample, per-
mitted to cool, is then reweighed and the moisture content determined.

     (3)  Reference:   N/A

Limitations:  The gas-burner method is used extensively for testing gravelly
material.  Two or more samples may be tested concurrently.   When care is
exercised to prevent overheating or burning the sample, the testing time
is usually about 1/2 hour.   The method is inaccurate for organic soils or
those containing particles with loosely bound water of hydration, unless
the drying is accomplished at a temperature of not more than 140°F (60°C)
for 1 hour or longer.

Status of the Method:  The gas-burner method is used extensively as a rapid
method for testing gravelly soils in field control of earthwork.

Calibration Procedure:  Calibrate against Method No.  1.

Documentation of Test:  Items to be recorded include the wet weight and the
dry weight.  No example data sheet is provided.
                                      G-7

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                                                                  Method  No.  4

 Parameter Measured:  Water Content

 Title of Test Method:  Alcohol Burning

 Principle of Test Method:  This method determines the water content of  a  soil
 sample by first weighing  it wet and then again after it has been dried  by
 alcohol burning.

 Test Method

     (1)  Apparatus:  Metal pan, balance, denatured alcohol and stirring  rods.

     (2)  Procedure:  This method determines the approximate moisture content
 of soil by burning alcohol that has been added to the soil.  General procedure
 consists of placing a weighted quantity of moist soil in a pan, adding  alcohol
 and stirring the mixture, then igniting the alcohol.  After ignition and  com-
 plete removal of the moisture by burning, the sample is reweighed and its
 moisture content calculated.

     (3)  Reference:  N/A

 Limitations:  The alcohol burning test is a rapid inexpensive method for  deter-
 mining the moisture content of soils.   The method is usable with non-cohesive
 and cohesive material.  The method should not be used however if the soil con-
 tains a larger proportion of clay, gypsum, calcareous matter or organic matter.
 A large quantity of alcohol is required for testing coarse gravelly material.
 For multiple burnings, testing time can take more than 1/2 hour.  In terms of
 safety the alcohol burning test possesses the potential for accidental  fire.
 Care should be exercised  not to have alcohol on hand or in an open storage
 container near the testing apparatus during the ignition phase of the test.
 The alcohol should be stored in a safety container.

 Status of the Method:  The alcohol burning method of obtaining the moisture
 content of soil in the field has given satisfactory results.  Its use in  the
 field has been established.

 Calibration Procedure:  Calibrate against Method No. 1.

 Documentation of Test:  Items to be recorded include the wet weight and the
xlry weight.  No example data sheet is provided.
                                      G-8

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                                                                  Method No. 5

Parameter measured:  Water Content

Title of Test Method:  Calcium Carbide (Speedy)

Principle of Test Method:  This method determines the water content of a soil
sample by measuring the pressure developed when measured quantities of the
soil sample and powdered calcium carbide are mixed.

Test Method

     (1)  Apparatus:  Calcium carbide pressure moisture tester, tared scale,
two each 1-1/4 in. steel balls, brush, cloth and scoop.

     (2)  Procedure:  The calcium carbide gas pressure method for determining
water content consists of mixing measured quantities of moist soil and
powdered calcium carbide in a closed chamber and measuring the pressure
developed by the formation of acetylene gas.  The reaction of calcium carbide
and water forms acetylene gas and calcium hydroxide.  The pressure developed
is directly related to the amount of water entering into the reaction.

     (3)  Reference:  AASHTO T 217.

Limitations:  Only two sizes of testers are commercially available to test
for moisture content using this method:  (1) 26 gram capacity model and
(2) a six-gram capacity model.   The small chamber capacities of these devices
control the soil sample size to be used.   As a result, this method is unsuit-
able for representative samples of coarse granular material.  AASHTO T 217
recommends that this method should not be used on granular material having
particles large enough to affect the accuracy of the test—in general any
appreciable amount retained on 4.75 mm sieves.   If a six-gram sample is used
(according to AASHTO T 217), the sample should not contain any particles that
will be retained on the 2.00 mm sieve.  The testing of heavy clays with this
method requires special handling.

Status of the Method:  The apparatus for this method is relatively inexpensive
and well adopted to field testing.   Use in the United States is extensive.
In the field the calcium carbide method has been used extensively in the
control of embankment construction.   Normal testing time is less than 10 min.
A moderate amount of training of operators is required.  The calcium carbide
method is a standard method for rapid water content determination referenced
under AASHTO.

Calibration Procedure:   A calibration curve is required.

Documentation of Test:   Items to be recorded include soil sample weight,
powdered calcium carbide weight and resultant gas pressure.  No example data
sheet is provided.
                                      G-9

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                                                                  Method No.  6

Parameter Measured:   Water Content

Title of Test Method:   Microwave Oven

Principle of Test Method:   This method determines the water content of a soil
by first weighing it wet and then again after it has been dried in the oven.

Test Method

     (1)  Apparatus:  Microwave oven suitable for drying, balance, specimen
containers.

     (2)  Procedure:  The procedure for this method is the same as that for
the Standard Oven-Dry method.   That is, a specimen is placed wet onto a bal-
ance and weighed.  It is then placed in a microwave oven and dried completely.
It is then weighed again.   The weight difference was the water content.

     (3)  Reference:  N/A

Limitations:  Microwave ovens are not noted for their drying ability.  There
are necessary safety precautions when using a microwave oven.

Status of the Method:   This method is not commonly used.  Although a microwave
oven heats much more rapidly than a conventional oven, it is an erratic dryer
at best.  Thus this method should probably only be used for soils expected to
have a relatively low water content.

Calibration Procedure:  Calibrate against Method no. I.

Documentation of Test:  Items to be recorded include the wet weight and the
dry weight.  No example data sheet is provided.
                                      G-10

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                                                                  Method No. 7

Parameter Measured:  Water Content

Title of Test Method:  Infrared Oven

Principle of Test Method:  This method determines the water content of a soil
by first weighing it wet and then again after it has been dried in the oven.

Test Method

     (1)  Apparatus:  Infrared oven suitable for drying, balance, specimen
containers.

     (2)  Procedure:  The procedure for this method is the same as that for the
Standard Oven-Dry method.  That is, a specimen is placed wet onto a balance
and weighed.  It is then placed in an infrared oven and dried completely.   It
is then weighed again.   The weight difference was the water content.

     (3)  Reference:  N/A

Limitations:  There are necessary safety precautions when using an infrared
oven.   Infrared ovens are generally not widely available.

Status of the Method:  This method is not commonly used.  It can yield rapid
results, however.   The method should be desirable to a large operation where
the benefits of rapid results outweigh the costs of the limitations above
and the initial investment.

Calibration Procedure:   Calibrate against Method No.  1.

Documentation of Test:   Items to be recorded include the wet weight and the
dry weight.   No example data sheet is provided.
                                      G-ll

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                                                                  Method No.  8

Parameter Measured:   Unit Weight

Title of Test Method:   Standard Laboratory Volumetric

Principle of Test Method:   This method determines the unit weight of an
undisturbed soil sample by measuring the weight and volume.

Test Method

     (1)  Apparatus:   Sampling tools, balance, water bath, volume measuring
device, oven and coating material  (e.g.  paraffin).

     (2)  Procedure:   This method of test is intended to determine the density
of cohesive soil in the natural state, compacted cohesive soil, and stabilized
soil by measuring the weight and volume of undisturbed samples.  The method
briefly consists of cutting out a block of soil, coating it with a known
amount of paraffin,  weighing to obtain the net weight of the sample and
immersing in an overflow volumeter to determine the net volume of the sample,
then dividing through for the unit weight.

     (3)  Reference:   AASHTO T 233.

Limitations:  The method is suitable for any material that remains intact
during sampling.  This method is particularly adaptable to irregularly shaped
specimens and soil containing gravel, shells, etc.   Sample size is not limited;
large samples with coarse aggregate can be tested.   This method is time
consuming.

Status of the Method:   This method is a nonstandard test when used in rela-
tion to compaction control.  However, periodic record sampling on compacted
embankments for dams usually entails obtaining block samples.  In addition,
if the sample is properly removed from the fill, this test provides for
index and engineering properties.

Calibration Procedure:  N/A

Documentation of Test:  Items to be recorded include the sample's net weight
and net volume.  An example data sheet is provided.
                                      G-12

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                                 UNIT WEIGHTS
PROJECT-
                               . LOCATION-
• TESTED BY.
SAMPLE NO.
ORIGINAL SAMPLE SITE
WT. CONTAINER + WET SOIL. DRAMS (w)
WT. CONTAINER +• DRY SOIL. GrJAMS 
% MOISTURE, (W«=WW/W««IOO)
DRY UNIT WT. L5S./FT.5




























































SAMPLE NO.
ORIGINAL SAMPLE SIZE
WT. CONTAINER + WET SOIL. ORAMS (w)
WT. CONTAINER * DRY SOIL. ORAMS (W*l
WT. MOISTURE, ORAM3 (wv»W-V*)
WT. CONTAINER + DRY SOIL. ORAMS (V)
WT. CONTAINER, ORAMS (*")
WT.'DRY SOIL. ORAMS lwsxw'.W*)
\ MOISTURE. «W^=Ww/W,»100)
ORY UNIT WT. LBS./rT.3




























































                                        G-13

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                                                                  Method No. 9

Parameter Measured:  Unit Weight

Title of Test Method:  Standard Laboratory Displacement

Principle of Test Method:  This method determines the unit weight of a soil
sample by determining the weight of the sample and the volume of its hole.

Test Method

     (1)  Apparatus:  Sampling tools, soil tray and pans, balances, measure,
drying equipment, two gallons of lubricating oil, and a gauge point.

     (2)  Procedure:  This method determines the density of soil in-place by
finding the mass and moisture content of a disturbed sample and measuring
the volume occupied by the sample using oil of a known density.   The method
can be performed fairly fast; however, a chief concern is the messiness caused
by the oil.  The general procedure consists of leveling the test site, digging
a hole in the compacted earthwork, weighing the material removed, measuring
the volume of the hole by placing a measured quantity of oil in it and calcu-
lating the wet unit weight by dividing the weight of the moist soil by the
volume of the hole.

     (3)  Reference:  AASHTO T 214.

Limitations:   This method may be used in testing materials with both fine and
coarse particles; however, the test is best suited for soils and soil-aggregate
mixtures that are relatively impervious.   The method may not be suitable for
testing materials having fissures, cracks, or large voids.

Status of the Method:  The oil displacement method is a conventional test in
the control of earthwork construction.  However, it often provides less
satisfactory results than the sand-cone method.

Calibration Procedure:   N/A

Documentation of Test:   Items to be recorded include the weight of the soil
sample and the volume of the oil.   No example data sheet is provided.
                                      G-14

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                                                                 Method No. 10

Parameter Measured:  Unit Weight

Title of Test Method:  Standard Field Sand-Cone

Principle of Test Method:  This method determines unit weight by determining
the weight of a soil sample and the volume of its hole.

Test Method

     (1)  Apparatus:  One-gallon jar, double cone assembly, baseplate and
accessories.

     (2)  Procedure:  The test consists of digging out a sample of the mate-
rial to be tested and weighing it.   The volume of the hole is then determined
by using the sand-cone.

     (3)  Reference:  ASTM D 1556.

Limitations:  The sand-cone has features which limit its usefulness.   The
method can be used satisfactorily,  however, if its limitations are recognized
and proper precautions observed.   The poured density of sand is affected by
atmospheric moisture and change in relative humidity; thus, the sand should
be calibrated before use.  Care should be exercised to avoid jarring and den-
si fying the sand during the filling procedure, and the test should not be con-
ducted during vibration of the site, such as by heavy equipment.   Sample size
is limited by sand supply.

Status of the Method:  The sand-cone test is a conventional test method for
earthwork control.  The method is reliable and a commonly used test to deter-
mine the density of in-place soil.   On Corps of Engineers earthwork projects
the test serves as the referee test for all other control tests used.   The
sand-cone test is widely used in cohesive soils and can be also used in soils
of low plasticity, including gravelly soils.   The test is not applicable in
clean sands or gravels or loose granular materials.   The method is applicable
to large and small projects.

Calibration Procedure:   Calibrate against Method No.  8, 9, or 10.

Documentation of Test:   Items to be recorded include the weight of the soil
sample and the volume of the sand.   No example data sheet is provided.
                                      G-15

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                                                                 Method No. 11

Parameter Measured:  Unit Weight

Title of Test Method:  Standard Field Rubber Balloon

Principle of Test Method:  This method determines unit weight by determining
the weight of a soil sample and the volume of its hole.

Test Method

     (1)  Apparatus:  Calibrated vessel, elastic membrane, pressure control
device, baseplate and accessories.

     (2)  Procedure:  This method is used for determining the in-place density
by removing soil from a hole, weighing the excavated material, and measuring
the volume of the hole by a liquid-filled (water) balloon under constant
pressure.  Chief advantages of the test are its operational simplicity and the
speed with which tests can be conducted.

     (3)  Reference:  ASTM D 2167.

Limitations:   For general use in clays and consolidated sands, the rubber
balloon apparatus provides good results.  The method is not suitable for very
soft soil which will deform under slight pressure or in which the volume of
the hole cannot be maintained at a constant value.   The method is not well
adapted to the measurement of volumes in loose granular material.  However,
of all  in-place density tests some soil  engineers recommend the water balloon
as the preferred method for granular soils.   The test is well adapted to small
and large projects.  Physical limitation of the apparatus restricts the size
of the test hole to approximately four or six inches in diameter and from six
to twelve inches in depth.

Status of the Method:  The water balloon test is widely used for determining
in-place density for the control of earthwork.   The method is used by the
Corps of Engineers and other agencies because of its application to a wide
range of materials and its past performance record.

Calibration Procedure:   N/A

Documentation of Test:   Items to be recorded include the weight of the soil
sample and the volume of water.   No example data sheet is provided.
                                      G-16

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                                                                 Method No. 12

Prameter Measured:  Unit Weight

Title of Test Method:  Standard Field Drive-Cylinder

Principle of Test Method:  This method determines the unit weight of a soil
sample by securing one in a known-volume tube and then weighing it.

Test Method

     (1)  Apparatus:  Acceptable drive cylinder, drive head, straightedge,
shovel, weight, scales, drying oven and airtight containers.

     (2)  Procedure:  The drive-cylinder method for determining in-place
density involves obtaining a relatively undisturbed soil sample by driving
a thin-walled cylinder into the soil with a special driving head.   Two proce-
dures are described in ASTM D 2937 for performing this test, one for testing
at the surface or at very shallow depths, usually less than 3 ft (1 m), and
one for testing at greater depths.   The general procedure for both depths
consists of driving a sampling tube into the soil, withdrawing the tube with
sample, trimming sample flush with ends of tube, weighing, then calculating
the unit weight of the soil by dividing the net weight of the sample by the
volume of the tube.

     (3)  Reference:  ASTM D 2937.

Limitations:   The drive-cylinder method of determining in-place density can
be used satisfactorily in moist, cohesive, fine-grained soils and in many
sands which exhibit tendencies toward cohesiveness.   The method is not
appropriate for sampling very hard soils which cannot be penetrated easily,
or for soils  of low plasticity which are not readily retained in the cylinder.
The destructive method sample size is limited by the sample tube.   The chief
disadvantage  of the test is that its limited to fine-grained soils.

Status of the Method:   The standard field drive-cylinder method is a conven-
tional test method in earthwork control.   It is, however, less accurate
than the sand cone or water balloon methods.

Calibration Procedure:   N/A

Documentation of Test:   Items to be recorded include the soil sample's weight.
No example data sheet is provided.
                                      G-17

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                                                                 Method No.  13

Parameter Measured:   Unit Weight

Title of Test Method:   Standard Nuclear Moisture/Density Gage

Principle of Test Method:   This method determines unit weight by a gamma
source and a gamma detector.

Test Method

     (1)  Apparatus:   A nuclear source emitting gamma rays, a gamma ray detector
and a counter.

     (2)  Procedure:   This method describes determination of the density of
soil and soil-aggregate in place through the use of nuclear equipment.   In
general, the total or wet density of the material under test is determined
by placing a gamma source and a gamma detector either on, into, or adjacent
to the material under test.  These variations in test geometry are presented
as the backscatter,  direct transmission, or air gap approaches.  The inten-
sity of radiation detected is dependent in part upon the density of the
material under test.   The radiation intensity reading is converted to measured
wet density by a suitable calibration curve.  Some commonly used sources of
gamma rays are radium, cobalt 60 and cesium 137.

     (3)  Reference:   ASTM D 2922

Limitations:  The method described is useful as a rapid, nondestructive tech-
nique for the in-place determination of the wet density of soils and soil-
aggregates.  The fundamental assumptions inherent in the method are that
Compton scattering is the dominant interaction and that the material under
test is homogeneous.   Test results may be affected by chemical composition,
sample heterogeneity, and the surface texture of the material being tested.
The technique also exhibits spatial bias in that the apparatus is more
sensitive to certain regions of the material under test.  The nuclear method,
applicable to a wide range of soil, requires a considerable experienced
operator to obtain reliable measurements.  A weakness in the nuclear method,
being nondestructive, is that a sample is not provided to determine the water
content with which the test can be compared.  In addition this method requires
equipment that utilizes radioactive materials which may be hazardous to the
health of the user.   Effective operator instructions together with routine
safety procedures are an essential part of the operation of equipment of this
type.

Status of the Method:  Nuclear gages offer a rapid and accurate means for
obtaining density values for a wide variety of materials.  Recent advances  in
the design of nuclear equipment and a better understanding of the nuclear
principles involved have led to increasingly widespread use of nuclear gages
in earth construction control work.

Calibration Procedure:  The apparatus must be calibrated against a reliable
direct method.

                                      G-18

-------
Documentation of Test:   Items to be recorded include the counter's gamma ray
counts.   No example data sheet is provided.
                                      G-19

-------
                                                                 Method No. 14

Parameter Measured:  Specific Gravity

Title of Test Method:   Standard Laboratory

Principle of Test Method:  This method determines the specific gravity of a
soil sample by the use of a pycnometer.

Test Method

     (1)  Apparatus:   A pycnometer and a balance.

     (2)  Procedure:   The procedure for this method is to procure a soil
sample, weigh it with the balance, and then determine its specific gravity
by the use of the pycnometer.

     (3)  ASTM D 854

Limitations:  N/A

Status of the Method:   This is the standard method.  It is widely used.

Calibration Procedure:  N/A

Documentation of Test:  Items to be recorded include the sample weight and
the pycnometer reading.  An example data sheet is provided.
                                       G-20

-------
Hane:
Date:
Sacale Iluabsro
Sheet Nunber
SPECIFIC GRAVITY DETERMINATIONS
Sample Number
Pyononeter Bottle Number:
Wt. Bottle •*• Water + Sample = WB =-
Temperature of Suspension ~ • T ~ '
Wt Bottle + Water at tenp T — W —

Date:
Evap. Dish No.
Wt, Sample + Pt ph Pry = _ 	 1
Wp^ght of Dish —


Wo + VTW - We
Remarks:


Saiaple Hucber
Pycnometer Bottle KuDber:
Wt. Bottle + Water + Sanple ~ Wfl~
Tespsrature of Suspension — T —
Wt. Bottle + Water at temp. T = Ww=

Date:
Evao. Dleh No.
Wt. Samp] ft •*• PI Rh Pry —
Wftlght of Dl ph *~~ i I.. I. 1
Dry Wt. Q* Son W_ =r

'"o * "w ~ ^e
Reaarka:


Sample Nunber . , _
Pyonoaeter Bottle Hunber:
Wt. Bottle •*• Water + Saaple — ^a~
Temperature of Suspension = T •=_
fft. Bottle •+• Water at te.-ap. T = Ww'=,
S ~~ >rt *• X T
"o "w "a
P«*f •
Evap. Dish No.
.., .„ Wt. Sample + DlBh Dry —
Weight of PI =h — 1
	 	 Dry Wt. of Soil W0 = 	



G-21

-------
                                                                 Method No. 15

Parameter Measured:   Grain-Size Distribution

Title of Test Method:   Standard Sieve Analysis (+200 Fraction)

Principle of Test Method:   This method determines the +200 fraction of a
soil sample by the use of a No. 200 sieve.

Test Method

     (1)  Apparatus:   A No. 200 sieve, that is a sieve with 200 openings per
inch, and balance.

     (2)  Procedure:   This is a method-dependent test.   A dried soil sample
is weighed, poured onto a No. 200 sieve, and shaken.  That amount of soil not
passing through the sieve is the +200 fraction.  The +200 fraction is then
weighed on the balance.

     (3)  Reference:   ASTM D 422.

Limitations:  The limitations of the method are its possible sources of error.
These include:  (a) overloading the sieve; (b) inadequate or incorrect shak-
ing; and (c) broken or damaged sieves.

Status of the Method:   This is the standard method.  It is widely used.

Calibration Procedure:  N/A

Documentation of Test:  Items to be documented include the weight of the dried
soil sample and the weight of the +200 fraction.   An example data sheet is
provided.
                                      G-22

-------
 I
ro
CO
PER CENT FINER BY WEIGHT
— KJCJfc-OlONlOO-OO
wt o OOOOOOOOOO
U S STANDARD SIEVE OPENING IN INCHES
6 43 2 1V4 1 % V4 V, 3 4 6














-







	

















~~T 	
—
- ..




! 1





















1


!
|




i




F






i
il ,


1
-,-t—

,-L
i
\ I



-\ 	
-\ — 1 	


1



I 1


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—









>







! I
X> 100 50
COMICS
SAMPLE NO





1
-t










r
-+
'I

I















1

















-
U S. STANDARD SIEVE NUMBERS HYDROMETER
8 10 1416 20 30 40 50 70 100 140 200
1









1












hh


~!--i — i — \- --
\
rrt"""
-it


i—
—


10 5
GRAVEL
COARSE
ELEV OR D6PTH





FINE






i 	








1







|

|
i














1

1










1

















j
1






1
1









I \ j

!




' \ ! ; ; !


^^^^
-H-.- ;-








1 05
GRAIN SIZE MILLIMETERS






i










1
































~h j
i













1
j






































1,1












































































































































0
10
20
30 g
0
$
40 *
tt
50 *
5
U
60 z
U
70 *
80
90
100
0.1 0.05 0.01 0.005 0.001
SAND
COARSE
MEDIUM
CLA55lf1CAT,ON





NAT W%





FINE
u





PI





SILT OR CLAY
pi





GRADATION CURVES

PROJECT

AREA
•ORING NO
DATE
                          ENGFORM
                                       2Q37      KHACB WES fOUM NO  1311. SEP 1962. WHICH IS OISOLETE
                                                                                                                                                                u S COVCKNMENT MINTING o

-------
                                                                 Method No. 16

Parameter Measured:  Grain-Size Distribution

Title of Test Method:  Amount of Soil Finer than No. 200 Screen (Wash)
Standard

Principle of Test Method:  This method determines the -200 fraction of a
soil sample by the use of a No. 200 sieve and washing.

Test Method

     (1)  Apparatus:   A No. 200 sieve and a balance.

     (2)  Procedure:   This method is similar to that described for determining
the +200 fraction.  However if the soil sample to be tested contains plastic
fines, drying will cause them to adhere to the fine sand grains, and the test
will yield erroneous results.   The solution is to weigh the dry sample
beforehand.   Pour it on the No. 200 screen.  Wash the sample to loosen the
fines and allow them to pass through the sieve.  Dry that amount of soil
remaining on the No.  200 screen and weigh it.   The two weight differences  is
then the fines content.

     (3)  Reference:   ASTM D 1140.

Limitations:   The significant limitation of this method is the extra time
required for washing and redrying.

Status of the Method:  This is the standard method.   It is widely used.

Calibration Procedure:   N/A

Documentation of Test:   Items to be documented include the dry weight of the
sample and the dry weight of the +200 fraction.  No example data sheet is
provided.
                                      G-24

-------
                                                                 Method No. 17

Parameter Measured:  Grain-Size Distribution

Title of Test Method:  Standard Laboratory Hydrometer (-200 fraction)

Principle of Test Method:  This method determines the grain-size distribution
of the -200 fraction of a soil sample by the use of Stokes1 Law and a standard-
ized hydrometer.

Test Method

     (1)  Apparatus:  A No.  200 sieve, a standardized hydrometer, a sedimenta-
tion cylinder, a thermometer and a beaker.

     (2)  Procedure:  This method determines the grain-size distribution of
that fraction of a soil sample passing the No.  200 sieve (the -200 fraction).
The method utilizes a deflocculating (dispersing) agent and Stokes1 law
to enable the different particle sizes to settle at different rates, thus
enabling the technician to determine their distribution.

     (3)  Reference:  ASTM D 422.

Limitations:   An experienced technician is required to perform this test
method.   Considerable time is required for sample preparation.  The test
itself requires several hours to perform.

Status of the Method:  This is the standard method.   As it is the only
"exact"  method for determining the percent silt sizes and the percent clay
clay sizes, it is widely used.

Calibration Procedure:   N/A

Documentation of Test:   Items to be documented include the dry weight of the
sample and the dry weights of the settled fractions.   Example data sheets
are provided.
                                      G-25

-------
Project
Boring Nc
HYDROMETER ANALYSTS



Date



Sample or Specimen No. | Classification
Dish No. Graduate No. Hydrometer No.
Dispersing agent used ; Quantity
Dispersing agent correction, C, = ; Meniscus correction, C =
Time














.p w
*H tH tt
!U M
S
Elapsed
Time
min














Temp
°C














Hydro.
Reading
(R')














Corrected
Reading
(R)














Dish plus dry soil
Dish
W
Dry soil o
Particle
Diameter
(D), mm












Temp
Correc-
tion
(m)











!
!





Specific
Gs =
Corrected
= hydro
The particle diameter (D) is calculated from Stoke 's equation usin
reading. Use nomographic chart for solution of Stoke 's equation
Hydrometer graduated in specific gravity W = total oven-dr
Partial percent finer = - — S_ x i2° (R - Cd +
S 0
Hydrometer graduated in grams per liter
Partial
Total p«
Remarks.
TechnicJ
percent
rcent fi
finer =

o
rtial percent finer
R - C, +m
d














Percent Finer-
Part ial














Total














gravity of solids,
hydrometer reading (R)
meter reading (R') + C
m
g corrected hydrometer
y wt of sample used for
combined analysis
' W = oven-dry wt in grains of soil used for
° hydrometer analysis
W = oven-dry wt of sample retained on No. 200
sieve
"s


an Computed hy Checked hy

CMC FORM 304? D 4 1 4 9 9
G-26

-------
ro
100
90
80
70
*-
O
| 60
S
| 50
z
8 40
K
UJ
0.
30
20
10
0
5C
U.S. STANDARD SIEVE OPENING IN INCHES U.S. STANDARD SIEVE NUMBERS HYDROMETER
6 43 2 1% 1 % tt H 3 4 6 8 10 1416 20 30 40 50 70100140 200














—












































1



























































































I






1
































1





















1

















1 !




















1























































1































1
















j



1












1











1


























1
























































1

























1 1











1











1
i
j





!







» 100 50 10 5 1 0.5
GRAIN SIZE MILLIMETERS
COMIES
SAMPLE NO.





GRAVEL
COARSE | FINE
ElEV OR DEPTH






































































































1
t \


























































































































































































0.1 0.05 0.01 0.005 0.0
SAND
COARSE
CLASSIFICATION





GRADATION CURVES
MEDIUM FINE
NAT W%





11





PI







PI






SILT OR CLAY




0
10
20
30 j
O
1U
"I
Of.
UJ
50 2
a
u
60 z
IU
O
Of
70 *
80
90
100
01
ROJECT

AREA


BORING NO
DATE
ENG
1 MAY 63
                                      REPLACES WES FORM NO  1241, SEP 1962, WHICH IS OBSOLETE
                                                                                                                                                                 US GOVERNMENT MINTING OFFtCI  I tf 3 Of — T0»- I2«

-------
                                                                 Method No. 18

Parameter Measured:   Grain-Size Distribution

Title of Test Method:   Pipette Method for Silt and Clay Fraction

Principle of Test Method:  This method determines the silt and clay fractions
of a soil sample by the use of a dispersing agent, Stokes1 law, and a pipette.

Test Method

     (1)  Apparatus:   A No. 200 sieve, a beaker and a pipette.

     (2)  Procedure:   The soil sample is deflocculated in a dispersing agent
for one hour.  The soil-water-agent mixture is then agitated and allowed to
sit.  Theroretically all the sand and silt sizes will have settled by then.
The water, with the suspended clay sizes, is then drawn off by the pipette.
The settled fraction is the original soil sample minus the clay fraction.  The
settled fraction is completely dried and passed through a No.  200 sieve.  The
fraction passing is the silt fraction; the fraction remaining is the sand
fraction.

     (3)  Reference:   Mills, 1970.

Limitations:  The method is less exact than the standard laboratory hydrometer
method.

Status of the Method:   The method lends itself well to field laboratory use
and is widely accepted.

Calibration Procedure:   N/A

Documentation of Test:   Items to be documented include the dry weight of the
sample, the dry weight of the settled fraction and the dry weight of the
silt fraction.  No example sheet is provided.
                                      G-28

-------
                                                                 Method  No.  19

Parameter Measured:  Grain-Size Distribution

Title of Test Method:  Decantation Method  for Silt and Clay  Fraction

Principle of Test Method:  This method determines the silt and clay fractions
of a soil sample by the use of a dispersing agent, Stokes1 law and
decantation.

Test Method

     (1)  Apparatus:  A No. 200 sieve and  a beaker.

     (2)  Procedure:  The soil sample is deflocculated in a  dispersing agent
for one hour.  The soil-water-agent mixture is then agitated and allowed to
sit.   Theoretically all the sand and silt  sizes will have settled by then.
The water, with the suspended clay sizes,  is then drawn off  by decantation
(careful pouring).   The settled fraction is the original sample minus the
clay fraction.   The settled fraction is completely dried and passed through
a No.  200 sieve yielding the silt fraction.

     (3)  Reference:  Mills, 1970.

Limitations:  The method is less exact than the standard laboratory hydrom-
eter method.  As is also more rudimentary than the pipette method,  it can
be less accurate than this method in execution.

Status of the Method:   The method lends itself well to field laboratory use
and is widely accepted.

Calibration Procedure:   N/A

Documentation of Test:   Items to be documented include the dry weights of
the sample,  the settled fraction and the silt fraction.   No example sheet
is provided.
                                      G-29

-------
                                                                 Method No. 20

Parameter Measured:   Liquid Limit

Title of Test Method:   Standard Multipoint

Principle of Test Method:   This method determines the liquid limit of a soil
sample by the use of the liquid limit device and a minimum of three trials.

Test Method

     (1)  Apparatus:  Evaporating dish, spatula, liquid limit device, grooving
tool and balance.

     (2)  Procedure: A soil sample is air dried.  Distilled water is added
and mixed thoroughly with the sample till it is ready to be tested.   A sample
is placed in the liquid limit device and divided by the grooving tool.  The
test is run till the soil  halves meet.   The result is plotted.   A minimum of
three trials are performed.

     (3)  Reference:  ASTM D 423.

Limitations:  The method requires considerable time and a laboratory environ-
ment to be performed.

Status of the Method:   The standard multipoint method is used for acceptance
or rejection of material or where a high degree of accuracy is required.

Calibration Procedure:  N/A

Documentation of Test:  Items to be recorded include the oven-dry weight of
the sample, the water content and the number of blows.   An example data
sheet is provided.
                                      G-30

-------
LIQUID AND PLASTIC LIMIT TESTS
For use of this form, see EM 1110-2-1906.
PROJECT
BORING N



0 SAIUIPI c iun

LIQUID LIMIT
RUN NO.
TARE NO.
WEIGHT
IN GRAMS

TARE PLUS WETSOIL
TARE PLUS DRY SOIL
WATER ™ „
TARE
DRY SOIL |w ,
WATER CONTENT, % w
NUMBER OF BLOWS




^
1 CONTENT, w
WATEF

1












	 1 	 1 	 , 	
|



1 i


1
\
1 1
1 I
r_ 1 	 L__.
i l _|-


	 -j 	 1 	 1 	 [ 	

| |

1 i


|
i i l









	


i 	 .-4-

	 !___













2












	 1 	










_:^-_t::.:-:.
I! IIUIIIIM



— — —








345 6




















.j.. 	 PI

PI


Symbol from *
- - . - - . . pl.isticity chart









5 10 20 30 40
NUMBER OF BLOWS
PLASTIC LIMIT NATURAL
HUN NO.
TARE NO
IGHT
RAMS
Ul O
3 7


TARE PLUS WETSOIL
TARE PLUS DRY SOIL
WATER |W w
TARE
DRY SOIL IW s
WATER CONTENT, % w
PLASTIC LIMIT
REMARK!
TECHNIC
i








2








345 CONTENT










AN COMPUTED BY CHECKED BY

U S GPO 1984-0-452-954/18650
    G-31

-------
                                                                 Method No. 21

Parameter Measured:   Liquid Limit

Title of Test Method:   Standard One Point

Principle of Test Method:   This method determines the liquid limit of a soil
sample by the use of the liquid limit device and one trial.

Test Method

     (1)  Apparatus:  Same as Method 20.

     (2)  Procedure:  Same as Method 20,  except that only one test is per-
formed and a simple formula is used to calculate the liquid limit.

     (3)  Reference:  ASTM D 423.

Limitations:   The method requires considerable time and a laboratory environ-
ment to be performed.

Status of the Method:   For the purposes needed at a hazardous waste disposal
facility the standard one point method will yield reasonable data and is
widely used.

Calibration Procedure:   N/A

Documentation of Test:   Items to be recorded include the oven-dry weight of
the sample, the water content and the number of blows.   No example data sheet
is provided.
                                      G-32

-------
                                                                 Method No. 22

Parameter Measured:  Plastic Limit

Title of Test Method:  Standard Laboratory

Principle of Test Method:  This method determines the plastic limit of a soil
sample, that is the lowest water content at which the soil can be rolled into
1/8 in. threads without breaking.
Test Method
     (1)
balance.
Apparatus:  Evaporating dish, spatula, suitable containers, and
     (2)  Procedure:  For a given soil sample begin at a water content esti-
mated to be greater than the plastic limit.  A good start point would be some-
what below the approximate liquid limit.   Shape the soil into an ellipsoidal
mass.  Roll the sample into 1/8 in.  threads.  Cut the threads into 6 to
8 pieces.  Repeat the process till the threads break at 1/8 in.   An oven-dry
moisture content determination at that point will yield the plastic limit.

     (3)  Reference:  ASTM D 424.

Limitations:   The method is simple and straightforward.

Status of the Method:   This is the standard method and is widely used.

Calibration Procedure:  N/A

Documentation of Test:  Items to be recorded include the oven-dry and wet
weight of the sample at the plastic limit.  An example data sheet is provided.
                                      G-33

-------
LIQUID AND PLASTIC LIMIT TESTS
For use of this form, we EM 1 1 1 0-2-1 906.
PROJECT

n»Tc

BORING NO. OAUDI r Mr,


LIQUID LIMIT
RUN NO.

WEIGHT
IN GRAMS

TARE NO.
TARE PLUS WET SOIL
TARE PLUS DRY SOIL
WATER |W w
TARE
DRY SOIL |w ,
WATER CONTENT, % w
NUMBER OF BLOWS


WATER CONTENT, w, %

1








2



















i

|




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| j ;

i "I i '
| j

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1
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5 10 20 30
NUMBER OF BLOWS
345 6












T






	
. . .. t .. LL

t" -'-'
4
4 	 PI







Symbol from
Dlastlcitu chart
	 |








40
PLASTIC LIMIT NATURAL
RUN NO
TARE NO.

WEIGHT
IN GRAMS

TARE
PLUS WET SOIL
TARE PLUS DRY SOIL
WATER |W
TARE
DRY SOIL |w s
WATER CONTENT, % w
PLASTIC LIMIT
REMARKS
1








2








345 CONTENT










TECHNICIAN


COMPUTED BY CHFCKFDBV


ENG FORM 3838 *U.S.OPO:19»W-«2-964/ia«eO
1 JUN65
G-34

-------
                                                                 Method No.  23

Parameter Measured:   Cohesive Soil Consistency

Title of Test Method:   Standard Unconfined Compression

Principle of Test Method:   This method uses a compression device to determine
the unconfined compressive strength of a soil sample:   that is the load per
unit area at which the specimen fails in simple compression.

Test Method

     (1)  Apparatus:   Compression device, sample ejector, deformation indi-
cator, vernier caliper, timer, balance and oven.

     (2)  Procedure:   An undisturbed sample is secured and a specimen prepared
as per the reference.   An estimate of the failure is made based on experience
with a similar material.  The specimen is placed in compression by uniformly
progressive loads at 30 second intervals till failure or 20% strain is
reached.  The results are plotted.

     (3)  Reference:   ASTM D 2166.

Limitations:  The method requires a laboratory environment, the securing of
an undisturbed sample (as described by ASTM Method D 1587), considerable
specimen preparation,  calculations and considerable time.

Status of the Method:   The method is the standard means for unconfined com-
pressive strength determination.   However because of its limitations it is
not commonly used in process control (because of more efficient methods) but
is widely used in acceptance testing.

Calibration Procedure:  The deformation indicator must be zeroed at the
beginning of the test.

Documentation of Test:  Items to be recorded include the moisture content of
the sample as well as the strain deformations at their respective loads.  An
example data sheet is provided.
                                      G-35

-------
                           UNCONFINED COMPRESSION TEST -  DATA SHEET
Soil Description .
                                                      Project.
                                                      Laborolory .
Boring No	
U	7.
                       Surface Elev._
Pocket Penetrometer, P.P. .
                                    _tsf    Specific Gravity, Gs_
                                                Dry Unit Weight,
                                                                                                         . pcf
 Diameter:.
 Proving Ring Conversion Factor:.
                Soil Specimen Measurements
_in.  Initial  Area, Ao:	if Initial Length, lo: _
        	    Corrected Area, A£  =
WATER CONTENT

Container No.
Wt. Cant. + W.I SoiKgms.)
Wt. Cant, f Dry SoiKgml.)
Wt. Container (gms.)
Wt Dry Soillgms.)
Wt Waler(gms.)
Wol.r Conlcnl|7.)
Top







Middle







Bottom lEnlire Kcmoiaed Sample
1
1


1

1
COMPRESSION TEST
Elapsed Time
(Min.)


























load Dial
Heading


























Load
lib,.)


























Vett. Dial
(in
-------
                                                                 Method No. 24

Parameter Measured:  Cohesive Soil Consistency

Title of Test Method:  Field Expedient Unconfined Compression

Principle of Test Method:  This method uses a field expedient compression
device to determine the unconfined compressive strength of a soil sample.

Test Method

     (1)  Apparatus:  Sample ejector, compression device, stress and deforma-
tion indicators, balance, oven and trimmer.

     (2)  Procedure:  A sample is secured and prepared.  An estimate of the
samples failure strength is made based on experience with a similar material.
The specimen is then placed in compression by uniformly progressive loads
till failure or a predetermined percent strain is achieved.   The results
are plotted.

     (3)  Reference:  TM 5-530, 1971 (U.  S. Army).

Limitations:  The method involves a procedure virtually identical to that
called for in the standard laboratory method.   However the apparatus used
in the field expedient method is less accurate,  less care is given to
sample preparation and the method itself is less accurate.

Status of the Method:   The method lies between the standard laboratory method
and the hand device methods in terms of accuracy and resources required.   The
standard laboratory method is the acce