GROUND WATER CONTAMINATION STUDIES
                    Handbook
                   Presented to:

       I U. S. ENVIRONMENTAL PROTECTION AGENCY
       *        Region VI, Dallas, Texas
               October 26th-28th, 1987
                   Presented by:

       INTERNATIONAL TECHNOLOGY CORPORATION
                  Austin, Texas

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 GROUND WATER  CONTAMINATION STUDIES

        Short Course Handbook
             Presented  to
U. S. Environmental Protection Agency
              Region VI
     October  26,  27,  and 28,  1987
             Prepared by
 International  Technology  Corporation

             October  1987

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                               TABLE OF CONTENTS

                                                                          PAGE
LIST OF TABLES                                                              vi
LIST OF FIGURES                                                           viii
INTRODUCTION                                                              xiii
ACKNOWLEDGEMENTS                                                           xvi
1.0  GROUND WATER HYDROLOGY                                                1-1
     1.1  HYDROLOGIC CYCLE                                                 1-5
     1.2  HYDROLOGIC PROCESSES OF GROUND WATER FLOW                        1-5
          1.2.1  Principles of Ground  Water Flow                          1-10
                 1.2.1.1  Darcy's Law                                     1-12
                 1.2.1.2  General Ground Water Flow Direction             1-14
          1.2.2  Aquifer, Aquitards, and Aquicludes                       1-15
                 1.2.2.1  The Aquifer, the Matrix in which
                          Ground Water Flows                              1-15
                 1.2.2.2  Aquicludes and Aquitards                        1-22
     1.3  GROUND WATER RESOURCES                                          1-23
          1.3.1  Description of Major  Aquifer Systems in EPA
                 Region VI States                                         1-23
                 1.3.1.1  Arkansas                                        1-23
                 1.3.1.2  Louisiana                                       1-26
                 1.3.1.3  New Mexico                                      1-29
                 1.3.1.4  Oklahoma                                        1-32
                 1.3.1.5  Texas                                           1-36
          1.3.2  Ground Water Use                                         1-40
     1.4  WELLHEAD PROTECTION REQUIREMENTS                                1-41
          1.4.1  Wellhead Protection Area Method Development              1-41
          1.4.2  Protection From Spills  (Immediate Zone)                  1-42
          1.4.3  Well Construction Standards                              1-42
                 1.4.3.1  Well Casings and Grouting                       1-42
                 1.4.3.2  Casing Installation                             1-44
                 1.4.3.3  PVC Casing                                      1-44
          1.4.4  Well Plugging Procedures                                 1-46
          1.4.5  Buffer Zone                                              1-46
          1.4.6  Protection From Bacteria                                 1-46

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                         TABLE OF CONTENTS  (Continued)

                                                                          PAGE
          1.4.7  Protection From Contamination by Naturally Occurring
                 or Synthetically Derived Organic Compounds               1-48
          1.4.8  Wellhead Protection Area Delineation Methods             1-49
                 1.4.8.1  Arbitrary or Calculated Fixed Radii             1-49
                 1.4.8.2  Simplified Variable Shapes                      1-49
                 1.4.8.3  Analytical Methods                              1-53
                 1.4.8.4  Hydrogeologic Mapping                           1-53
                 1.4.8.5  Numerical Flow/Transport Models                 1-53
                 1.4.8.6  Conclusion                                      1-53
2.0  GROUND WATER CHEMISTRY                                                2-1
     2.1  CONSTITUENTS IN GROUND WATER                                     2-1
          2.1.1  Inorganic Constituents                                    2-4
          2.1.2  Organic Constituents                                      2-7
     2.2  SIGNIFICANCE OF LOW CONCENTRATIONS OF ORGANIC AND INORGANIC
          COMPOUNDS                                                       2-14
3.0  INVESTIGATIVE TECHNIQUES                                              3-1
     3.1  BACKGROUND DATA                                                  3-1
          3.1.1  Soil Data                                                 3-2
          3.1.2  Boring  Inventory                                          3-3
          3.1.3  Geology                                                   3-4
          3.1.4  Ground Water Data                                         3-5
          3.1.5  Aerial  Photos                                             3-6
          3.1.6  Landsat Image Data                                        3-6
          3.1.7  Additional Sources                                        3-7
     3.2  FIELD INVESTIGATIVE TECHNIQUES                                   3-7
          3.2.1  Geophysical Methods                                       3-7
                 3.2.1.1  Earth  Electrical Resistivity Surveys             3-8
                 3.2.1.2  Ground Penetrating Radar                        3-18
                 3.2.1.3  Magnetic Surveys                                3-20
          3.2.2  Exploratory Drilling                                     3-25
                 3.2.2.1  Drilling Methods                                3-28
                 3.2.2.2  Logging Techniques                              3-31
          3.2.3  Monitor Wells                                            3-41
                 3.2.3.1  Well Location                                   3-41

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                         TABLE  OF  CONTENTS  (Continued)

                                                                          PAGE
                 3.2.3.2  Screen Placement                                3-46
                 3.2.3.3  Installation Methods                            3-46
                 3.2.3.4  Materials of Construction                       3-54
                 3.2.3.5  Well  Development Methods                        3-58
          3.2.4  Lysimeters                                               3-63
                 3.2.4.1  Installation and Operation of
                          Suction Lysimeters                              3-63
                 3.2.4.2  Installation and Operation of
                          Pan Lysimeters                                  3-73
                 3.2.4.3  Other Information on Lysimeters                 3-74
          3.2.5  Tensiometers                                             3-74
          3.2.6  Cone Penetrometer Surveys                                3-75
                 3.2.6.1  Description                                     3-76
                 3.2.6.2  Cone Penetrometer Log Correlation               3-80
                 3.2.6.3  Other Uses                                      3-80
          3.2.7  Soil Gas/Vapor Monitoring                                3-83
                 3.2.7.1  Liquids and Gases as Flow Media                 3-84
                 3.2.7.2  Soil  Vapor Sampling                             3-84
                 3.2.7.3  Sample Analysis                                 3-85
4.0  MIGRATION OF CONTAMINANTS/AQUIFER CHARACTERIZATION                    4-1
     4.1  UNSATURATED ZONE                                                 4-1
          4.1.1  Effect of Thickness                                       4-1
          4.1.2  Effect of Composition                                     4-3
          4.1.3  Effect of Unsaturated Permeability                        4-5
     4.2  SATURATED ZONE                                                   4-7
          4.2.1  Direction and Rate of Ground Water Flow                   4-7
          4.2.2  Permeability                                              4-9
          4.2.3  Density of Contaminant Plume                             4-13
          4.2.4  Chemical Reactions                                       4-16
     4.3  AQUIFER CHARACTERIZATION TESTS                                  4-19
          4.3.1  Field Tests                                              4-19
                 4.3.1.1  Aquifer Characteristics Definitions             4-19
                 4.3.1.2  Steady State (Equilibrium) Method               4-21

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                         TABLE  OF  CONTENTS  (Continued)
                                                                          PAGE
                 4.3.1.3  Transient (Non-Equilibrium, Non-Steady)
                          Methods                                         4-29
                 4.3.1.4  Conducting An Aquifer Characteristics Test      4-38
                 4.3.1.5  Test Design and Analysis                        4-40
                 4.3.1.6  Slug Tests                                      4-45
                 4.3.1.7  Field Permeameter Test                          4-53
          4.3.2  Laboratory Tests                                         4-53
                 4.3.2.1  Index Tests                                     4-56
                 4.3.2.2  Permeability Tests                              4-60
5.0  HEALTH AND SAFETY WITH RESPECT TO GROUND WATER INVESTIGATIONS         5-1
     5.1  JOB-SPECIFIC HEALTH AND SAFETY PLANS                             5-1
          5.1.1  Assignment of Responsibilities                            5-1
          5.1.2  Employee Training and Information                         5-2
          5.1.3  Employee Decontamination                                  5-2
          5.1.4  Personal Protective Equipment and Procedures              5-2
          5.1.5  Regulated Areas                                           5-4
     5.2  GENERAL WORK PRACTICES                                           5-4
          5.2.1  Personal and Ambient Air Monitoring                       5-4
          5.2.2  Emergency Procedures                                      5-4
     5.3  PROBLEMS ASSOCIATED WITH HEALTH AND SAFETY PROGRAMS              5-5
6.0  SAMPLE INTEGRITY                                                      6-1
     6.1  SAMPLE COLLECTION AND HANDLING                                   6-1
          6.1.1  Decontamination and Sampling Procedures for Soils         6-1
          6.1.2  Collection of Ground Water Samples             '           6-3
                 6.1.2.1  Static Water Level Measurements                  6-3
                 6.1.2.2  Detection of Immiscible Layers                   6-4
                 6.1.2.3  Well Purging                                     6-5
                 6.1.2.4  Sampling Devices                                 6-6
          6.1.3  Proper Handling of Samples                                6-9
                 6.1.3.1  Sample Preservation                              6-9
                 6.1.3.2  Chain-of-Custody                                6-15
                 6.1.3.3  Preparation, Packaging, Handling
                          and Shipping                                    6-17
                                      IV

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                         TABLE  OF  CONTENTS  (Continued)
                                                                          PAGE
                 6.1.3.4  Sample Storage                                  6-17
          6.1.4  RCRA Sampling Versus Real World Sampling                 6-18
     6.2  SAMPLE ANALYSIS AND DATA INTERPRETATION                         6-19
          6.2.1  Use of Blanks                                            6-20
          6.2.2  Choice of Analytical Parameters                          6-20
          6.2.3  Detection Limits                                         6-24
          6.2.4  Analytical Precision and Matrix Effects                  6-33
          6.2.5  Sources of Contamination in the Laboratory               6-35
          6.2.6  Adsorption of Air Emissions                              6-36
          6.2.7  Sources of Sample Contamination in the Field              6-36
          6.2.8  Physical and Chemical Concerns                           6-40
7.0  GROUND WATER MODELING                                                 7-1
     7.1  FLOW MODELS                                                      7-1
     7.2  MASS TRANSPORT MODELS                                            7-3
     7.3  GUIDELINES TO CHOOSING AND USING A MODEL                         7-4
     7.4  USE OF MODELS IN CONTAMINATION STUDIES                           7-5
     7.5  AVAILABILITY OF MODELS                                           7-6
8.0  BIBLIOGRAPHY                                                          8-1

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                                LIST OF TABLES
TABLE NO.                              TITLE                              PAGE
   1-1             Contamination of Major Aquifers                         1-2
   1-2             Contamination of Shallow Aquifers                       1-3
   1-3             Comparison of Contaminated vs. Uncontaminated
                   Ground Water                                            1-4
   1-4             Permeability                                           1-11
   1-5             Aquifer Definitions                                    1-17
   1-6             Methods of Management of the  Immediate Area            1-43
   1-7             Wellhead Protection Area Delineation Methods           1-50
   2-1             Distribution of Chemical Constituents in
                   Natural Waters                                          2-2
   2-2             Texas and EPA Standards for Drinking Water              2-3
   2-3             Trace Metal Concentrations:   Range in Coal, Ash
                   Bedrock, Soil, and Plants                               2-8
   2-4             Occurrence of Metals                                    2-9
   2-5             EPA Hazardous List Compounds  Found in Coal             2-13
   2-6             National Urban Runoff Program (NURP) Priority
                   Pollutant Sampling Results                             2-15
   2-7             Range of Chemical Constituents Found in 20
                   Peat Samples from Three Canadian Bogs                  2-18
   2-8             Chemical Analysis of Water Samples From Peat
                   Bogs in Canada                                         2-19
   3-1             Resistivities of Different Rock and Sediment Type       3-9
   3-2             Resistivity Values for Selected Sediments              3-10
   3-3             Drilling Methods                                       3-29
   3-4             Unified Soil Classification System                     3-33
   3-5             Field Identification Procedures for Fine-grained
                   Soils or Fractions                                     3-35
   3-6             Well Casing and Screen Materials                       3-56
   3-7             Leachate Analysis of #200 Novacite                     3-68
   3-8             Physical and Chemical Data on Novacite                 3-68
   4-1             Sample Field Permeability Calculation                  4-54
   6-1             Addition of Acidic Preservative Prior to Filtering     6-12
   6-2             Travel and Field Blank Results                         6-21
                                       VI

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                          LIST OF TABLES (Continued)
TABLE NO.                              TITLE                              PAGE
   6-3             Results of Organic Analysis of Laboratory Blanks
                   Oklahoma State Department of Health Laboratory
                   (Matrix Unknown)                                       6-22
   6-4             Results of Organic Analysis of Laboratory Blanks
                   Gulf South Research Institute, New Orleans, LA         6-22
   6-5             Organic Compounds Found in Method Blank Analysis       6-23
   6-6             Volatile Hazardous Substance List Compounds            6-25
   6-7             Acid Extractable Hazardous Substance List Compounds    6-28
   6-8             Base/Neutral Extractable Hazardous Substance
                   List Compounds                                         6-29
   6-9             QC Limits for Water and Soil                           6-34
   6-10            Organic Analyses of Well Water and Corresponding
                   Field Blanks - 2,4-Oinitrotoluene,
                   2,6-Dinitrotoluene                                     6-37
                                      vii

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                                LIST OF  FIGURES
FIGURE NO.                             TITLE                              PAGE
   1-1             Hydrologic Cycle                                        1-6
   1-2             Flow in Porous Sediments                                1-8
   1-3             Diagram Depicting Aquifer Terms                         1-9
   1-4             Darcy Tube                                             1-13
   1-5             Approximate Altitude of Water Levels in Wells
                   Completed in the Goliad Sand, 1977-1978                1-16
   1-6             Plots of Permeability Versus Porosity                  1-19
   1-7             Plot of Permeability Versus Grain Size                 1-20
   1-8             Principal Aquifers in Arkansas                         1-24
   1-9             Principal Aquifers in Louisiana                        1-27
   1-10            Principal Aquifers in New Mexico                       1-30
   1-11            Principal Aquifers in Oklahoma                         1-33
   1-12            Major Aquifers in Texas                                1-37
   1-13            Minor Aquifers in Texas                                1-38
   1-14            Well Casing and Completion Methods                     1-45
   1-15            Fixed Radius Method for WHPA Delineation               1-51
   1-16            Variable Shapes for WHPA Delineations                  1-52
   1-17            Analytical Method for WHPA Determination               1-54
   1-18            Hydrogeologic Mapping for WHPA Determination           1-55
   1-19            WHPA Comparison for Three Methods                      1-56
   3-1             Electrical Resistivity Electrode Configuration         3-12
   3-2             Resistivity Data Sheet                                 3-14
   3-3             Resistivity Sounding                                   3-16
   3-4             Resistivity Survey of a Salt Water Disposal Pond       3-17
   3-5             Electrical Resistivity Sounding                        3-19
   3-6             Block Diagram of Fluxgate Magnetometer                 3-22
   3-7             Example of Typical Magnetic Anomaly                    3-24
   3-8             Magnetic Survey Results                                3-26
   3-9             Magnetic Contour Map of a Superfund Site in
                   Arkansas                                               3-27
   3-10            Comparison of Geophysical and Geologic Log             3-37
   3-11            Example of a Gamma Ray Log Compared to the
                   Stratigraphic Log Determined by the Driller            3-39
                                     v i i i

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                          LIST  OF  FIGURES  (Continued)
FIGURE NO.                             TITLE                              PAGE
   3-12            Delineation of Confining Zone by Gamma Log
                   Which Were Not Apparent in Grab Samples of the
                   Mud Rotary Cuttings                                    3-40
   3-13            Cross Section A-A' Based on Drillers Log Description   3-42
   3-14            Cross Section A-A' Based on Natural Gamma Ray Logs     3-43
   3-15            Potential Paths for Subsurface Migration of Waste      3-45
   3-16            Cluster Well Completions                               3-47
   3-17            Completion of a Monitor Well Using Mud Rotary
                   Drilling                                               3-50
   3-18            Manganese Concentrations vs. Time of Pumping-Data
                   from Well Shown in Figure 3-15                         3-52
   3-19            Monitor Well Installation Diagram                      3-53
   3-20            Monitor Well Surface Completion                        3-55
   3-21            G. C. Scan Water Sample from Monitor Well
                   Constructed with PVC Pipe and Glue                     3-59
   3-22            G. C. Scan - PVC Pipe and Glue in Distilled Water      3-60
   3-23            Lysimeter Vacuum                                       3-64
   3-24            Pressure-vacuum Lysimeter                              3-65
   3-25            Modified Pressure-vacuum Lysimeter                     3-66
   3-26            Sampling and Installation of Pressure-vacuum
                   Lysimeters                                             3-69
   3-27            Sampling and Installation of Vacuum Lysimeters         3-70
   3-28            Alternate Lysimeter Installation                       3-71
   3-29            Cone Penetrometer and Instrument Log                   3-77
   3-30            Soil Classification Chart for Standard Electric
                   Friction Cone (After Douglas and 01 sen, 1981)          3-78
   3-31            Comparison of Soil Boring, Electric Logs, and
                   Cone Penetrometer Logs                                 3-79
   3-32            Cross-Section from Cone Penetrometer Logs              3-81
   3-33            Isopach Map of Stratigraphic Zone "A"                  3-82
   4-1             Schematic Diagram of Contaminant Flow in an
                   Unconfined Homogeneous Aquifer                          4-2
   4-2             Effects of Unsaturated Zone Lithology on
                   Contaminant Migration                                   4-4

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                          LIST OF FIGURES  (Continued)
FIGURE NO.                             TITLE                              PAGE

   4-3             Suction and Permeability Versus Degree of
                   Saturation for Compacted Fine Clay (Olson and
                   Daniel, 1979)                                           4-6

   4-4             Schematic Diagram of Flowlines in the Vicinity
                   of a Potentiometric Mound                               4-8

   4-5             Effect of Differences in Transverse Dispersivity
                   on Shapes of Contamination Plumes (Miller, 1980)       4-10

   4-6             Altitude of Water Levels, Deep Aquifer, Showing
                   Mounded Water Surface Under a Cooling Lake Near
                   Corpus Christi, Texas, April 14, 1981                  4-11

   4-7             Potentiometric Surface Map Before and After
                   Ground-Water Mounding                                  4-12

   4-8             Migration of Contaminant Plume with Density
                   Equal to Ground Water                                  4-14

   4-9A            Contaminant Plume with Density Greater than
                   Ground Water                                           4-15

   4-9B            Contaminant Plume with Density Less than the
                   Ground Water                                           4-15

   4-10            Cross Section of Disposal Site on the Texas
                   Gulf Coast                                             4-17

   4-11            Graphical Concepts of the Hydraulic Conductivity
                   and Transmissivity                                     4-20

   4-12            Graphical Concepts of Hydraulic Gradient               4-22

   4-13            Graphical Concept of Storage Coefficient and
                   Storativity (After Heath, 1983)                        4-23

   4-14            Various Terms Used in the Equilibrium Equation
                   for a Confined Aquifer                                 4-26

   4-15            Various Terms Used in the Equilibrium Equation
                   for an Unconfined Aquifer                              4-27

   4-16            Graphic Depiction of Cone of Depression as Defined
                   by Observations in Three Wells                         4-28
   4-17            Theis Method of Superposition for Solution of the
                   Nonequilibrium Equation Using a Reverse Type Curve     4-32

   4-18            Type Curves for Analysis of Pumping Test Data to
                   Evaluate Storage Coefficient and Transmissivity
                   of Leaky Aquifers                                      4-34

   4-19            Graphic Depiction of the Jacobs Straight Line
                   Method for Analyzing Aquifer Test Data                 4-35

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                          LIST OF FIGURES  (Continued)
FIGURE NO.                             TITLE                              PAGE
   4-20            Semilog Plot of Data from Three Observation Wells for
                   Distance Drawdown Analysis (After Driscoll, 1986)      4-37
   4-21            Time-drawdown Plot for a Well Discharging 2,700
                   gpm (After Driscoll, 1986)                             4-42
   4-22            Drawdown Data for 6-in. (152-mm) Test Well in
                   Brewster, Minnesota (After Driscoll, 1986)             4-42
   4-23            Drawdown Data Showing Barometric Effects (After
                   Hall Southwest, 1983)                                  4-43
   4-24            Recovery Data Showing Effects of Nearby
                   Intermittently Pumping Wells                           4-44
   4-25            Well Into Which a Volume, V, of Water is Suddenly
                   Injected for a Slug Test of a Confined Aquifer         4-47
   4-26            Type Curves for Slug Test in a Well of Finite
                   Diameter                                               4-48
   4-27            Geometry and Symbols of Partially Penetrating
                   Partially Perforated Well in Unconfined Aquifer
                   with Gravel Pack or Developed Zone Around Perforated
                   Section (Bouwer and Rice, 1976)                        4-50
   4-28            Curves Relating Coefficients A, B and C to
                   L/rw (From Bouwer and Rice, 1976)                      4-51
   4-29            Field Permeameter Installation                         4-55
   4-30            Plasticity Chart                                       4-58
   4-31            Permeameter Cell                                       4-62
   4-32            Pressure Board                                         4-63
   4-33            Influence of Using Distilled Water (from
                   Wilkinson, 1969)                                       4-65
   4-34            Effect of Temperature on Permeability                  4-66
   5-1             Tailgate Safety Meeting Form                            5-3
   5-2             Emergency Numbers Form                                  5-6
   6-1             Concentrations of Chemical Parameters vs.
                   Pumping Time                                            6-7
   6-2             Field Refrigeration of Samples Using Water Ice         6-13
   6-3             Bottles Placed in Crushed Ice Chilled to 40ฐC,
                   and Transferred to Ice Chest Pre-Chilled with
                   Blue Ice                                               6-13
   6-4             Field Refrigeration of Sample Using Blue Ice           6-14
   6-5             Chain-of-Custody Record                                6-16
                                      XI

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                          LIST OF FIGURES (Continued)
FIGURE NO.                             TITLE                              PAGE

   6-6             Flow Behavior of Leachate from a Surface
                   Impoundment                                            6-44
                                      XII

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                                 INTRODUCTION

PURPOSE OF SEMINAR
The Southwest is blessed with an abundance of ground water.   This abundance of
water, the  fact that the  Sunbelt  has always been an attractive  location for
industry, and the  general  lack of understanding of  ground  water systems have
resulted  in  numerous  occurrences of ground water contamination.   The purpose
of  this  seminar is  to  acquaint the  regulatory  staff  with the  potential  for
pollution from  man's  activities  and  to  demonstrate  study  techniques that will
enable them  to  determine  the extent of  ground  water problems  at individual
sites.

Recent federal  and  state  regulatory programs  have had  an effect  on  future
siting  and  construction  of  waste  facilities.    New  construction  standards
should reduce the  incidences of ground  water pollution in the  future.   How-
ever, the extent of  contamination  from  existing  and  closed  facilities must be
addressed if we are to have sufficient, good quality water for future economic
growth and to meet the legislated goals for the environment.

This  seminar does  not pretend to be  a state-of-the-art  course as the state of
the art  changes each minute.  Advances  in  knowledge about  contaminant  migra-
tion  are  occurring  at a  tremendous  pace.   However,  regardless of the state of
knowledge, unless regulators  understand the procedures by which investigations
are  conducted,  and   how they can  be conducted, then  reports  from  industry
cannot be properly evaluated.

At  the  conclusion  of this  seminar,  the participant should be  able to  review
reports  from industry  and/or  their  consultants  and  determine  if  adequate
information  has been  developed  to  determine the  pollution potential of  new or
existing disposal sites.  The participants  should be able to take the raw data
presented  in these reports and develop their own  conclusions  about the site.
The  seminar  should  also  assist those who  will  be  required to  conduct field
evaluations  of  facilities regulated under the Resource Conservation and Recov-
ery Act  (RCRA).
                                     xn i

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This course and other  similar  ones  have  been  presented  to  regulatory  agencies
several times.  One common  concern  about such  courses  is  the  problem  of regu-
lators requiring  a company  or consultant to  "do  something"  because of  what
they have  "just  learned  in a  short course."   What are  we  striving  to promote
in this course  is  the ability to think  through data with  an  understanding  of
how the data  was  obtained,  which allows the  individuals to reach  independent
professional opinions.   We  are not presenting the right way  or  the only  way,
but instead are presenting only one way.

INTRODUCTION TO SPEAKERS
Bob Kent is a certified  ground water  professional  and  professional  geological
scientist  with  over   13  years  of  experience  in  the  area  of  ground  water
management.   His  experience has  been  obtained by  working for  administrative
agencies, private industry, and municipal and federal  governments.   Mr.  Kent's
major areas of  experience are related to ground water  contamination  studies,
subsurface  injection  systems,  waste  management  techniques,  and ground  water
resource evaluations.

Typical ground water contamination projects undertaken  by  Mr.  Kent  include the
development and supervision of a ground water contamination  study  of a large
regional aquifer in the Texas  Panhandle,  and the performance of  field  investi-
gations of  ground water  contamination  from  waste disposal  sites.   Mr. Kent is
the  author of  numerous  papers  on  injection  systems,  ground water  recovery
systems, and waste management.

Ed  Fendley   is  the   acting   supervisor  of   the  engineering   staff  of  IT
Corporation's Austin  office.   Mr.  Fendley  is a project engineer  and manages
projects concerned with  the design of hazardous waste  treatment and  disposal
facilities, site  assessment,  and  site remediation.   His  experience  includes
the design  of hazardous  waste land disposal  units,  closure  alternatives for
hazardous  units,  ground  water recovery  systems,  and   permitting  assistance.
Representative  ground  water  contamination  and  recovery projects   include
conceptual design, feasibility studies, and installation.

Mark  Katterjohn is  a project geologist  with seven years of  experience  in
geology,  geophysics,   and  chemistry.    His  experience  in ground  water  and
                                      xiv

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subsurface geology  has been  gained  through working for technical  consulting
firms  and state  agencies.    Over  the  last  few  years,  Mr.  Katterjohn  has
evaluated subsurface  conditions  related to  ground  water occurrence,  quality,
usage, and contamination  as well  as  injection  well  practices.   His experience
includes  evaluation  of  the  hydrology  and geology  of single  and  multiple
aquifer systems of  regional  and  site specific scope  in  the  United  States  and
abroad.   Mr.  Katterjohn  has prepared and  presented  several  courses on ground
water sampling and data interpretation and ground water contamination studies.

EXPLANATION OF SEMINAR HANDBOOK
The  seminar  is primarily  a series of  lectures  by  speakers  who are  relating
their  practical   knowledge  and  experience  in  the  subjects covered.    This
handbook  is not a textbook to be reiterated during the course,  but  is provided
as  a  supplementary  material  to  the  content  of  the  lectures.   While  the
lectures  are  geared  toward  the overall content of  the  handbook, they may  not
follow the  text  and  substantial  additional  information will be presented  in
the  lectures.
                                      xv

-------
                                ACKNOWLEDGMENTS

This seminar handbook was prepared by International Technology Corporation.  A
large portion of the book has been adapted from previous course books prepared
by Underground Resource Management, Inc.  A number of past and current employ-
ees of these firms have contributed time to assemble the information presented
here and in the course presentation.  It is not possible to list all the indi-
viduals  here.   Major  contributions that  have  not been  previously presented
have  been  made to this  new book.   The contributors of  this  new  information
are:   Mark  Katterjohn,  Bob Krasko, Perry  Mann,  Ed Fendley,  and Phil Bullock.
Additional  staff  members who  have worked  in  the preparation  of  this  course
are:   Charlie  Mauldin,  Kathy  Payne,  Terry  Moody, Jene Thomas,   and  Elaine
AlIan.
                                      xvi

-------
     SECTION  1.0
GROUND WATER HYDROLOGY

-------
                          1.0  GROUND WATER HYDROLOGY

The term  "ground  water"  refers to water occupying  the  voids  within a geologic
stratum.  This saturated zone is distinguished from the unsaturated zone where
the voids are filled with both water and  air.   The  water-bearing formations of
the earth's  crust act as  conduits  for the transmission of  and  as reservoirs
for the storage of water.

Over the years, various agencies and consultants have conducted investigations
into the quality  and quantity of ground water  in the region.   These investiga-
tions have  documented  numerous  site-specific  examples of ground  water  pollu-
tion.  Regional water quality contamination is not  indicated, although in some
areas of the state, over 1,500 acres of ground water have been affected  from a
single evaporation pond.

The areas of the  region  where major ground  water contamination is most  likely
to occur  corresponds to  the  outcrop area  of major  and  minor aquifers.  Fortu-
nately, many of these areas are not heavily industrialized and although  numer-
ous cases of ground water contamination have occurred,  the effects are primar-
ily local.  Table 1-1 is a listing of several  cases of ground water contamina-
tion where  the contaminated  aquifer is  the  only  ground water  source  in  the
area.   Table  1-2 is a  list  of  occurrences  of  shallow  aquifer contamination
where the aquifer is not  a source  of drinking water.  These cases are primar-
ily  in  the Texas Gulf Coast area  where  numerous  shallow  sands  exist  in an
otherwise  clay soil environment.   Generally,  this  type of  contamination is
restricted to the general vicinity of the plant.

Frequently,  the  waste  streams  contain  greater concentrations  of  naturally
occurring substances than  the native ground water.   Table 1-3 is a comparison
of water  quality  data  of several wells before  and  after contamination.  Data
presented  in  other sections  of  this  seminar  handbook demonstrate  the  diffi-
culty of determining if an aquifer  is contaminated.  Frequently, contamination
can be  identified by analysis for  the  normal  ground water constituents, which
exist in  different  concentrations than in  the wastewater.   In order to evalu-
ate sites  which may contribute  to  ground water problems,  an understanding of
the hydrology  is  required.
                                      1-1

-------
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                                                                   1-2

-------
                                    TABLE 1-2

                        Contamination of Shallow Aquifers
INDUSTRY TYPE
Petrochemical**
Power plant
Petrochemical**
Petrochemical**
Steel Pipe
Manufacturer
Chemical
Iron and Plastic
Pipe Manufacturer
POLLUTION SOURCE
Abandoned disposal
site
Cooling lake
Lagoons
Lagoons
Effluent Ponds, Sludge
Drying Basins
Effluent Ponds
Sludge Drying Lagoons
CONTAMINANTS FOUND
IN GROUND WATER
High TDS, arsenic,
phenols
High TDS*
Phenols, chlorin-
ated hydrocarbons
High TDS*
High TDS*, Iron (1460mg/l)
High TDS*, Cadmium,
Chromium, Lead, Nickel,
Silver, Barium, Selenium
High TDS*, F
EFFECTS OF
CONTAMINANTS
shallow unused jquifei
no damage to deeper
regional aquifer -
some discharge to
surface water
some surface damage,
shallow aquifer in
plant contaminated,
slight leakage Uu u
aquitard and some
effect on the region-
al aquifer
local effects in
plant area on
shallow sands - no
danger- to regional
system - possible
migration off
plant along pipe-
lines, drainage
ditches, etc.

Local effects in plant
area on shallow
sands - future possi-
bility of migr at ion
to local water wells
Local effects in
plant area on shallow
sands - future possi-
bility of migrat ion
to local water wells
Minimal local con-
tamination of
shallow aquifer-.
Negligible chance of
migration of contami-
nants to deeper
aquifers
 *Chemical  analysis in Table  1-3.
**More than one documented case.
                                       1-3

-------
                                           TABLE  1-3

                Comparison  of Contaminated  vs. Uncontamlnated  Ground Water
Domestic well before and
after contamination by cooling
tower blowdown
Domestic well before and after
contamination by sewage disposal
ponds
Domestic well before and after
contamination by effluent from
magnesium plant
Monitor well before and after
contamination by salt water
pond
Monitor well before and after
initial influence of cooling
reservoirs
Monitor well before and after
contamination by leachate
from disposal site
An uncontaminated shallow
monitor well and a monitor
well completed at the same
depth, contaminated by pond
effluent
An uncontaminated shallow
monitor well and a monitor
well, completed at the same
depth, contaminated by pond
effluent
An uncontaminated shallow
monitor well and a monitor
well, completed at the same
depth, contaminated by pond
effluent
An uncontaminated area well
compared to a contaminated
monitor well
An uncontaminated area well
compared to a contaminated
monitor well

B
A
B
A
B
A
B
A
B
A
B
A
UC
C
UC
C
UC
C
UC
C
UC
C
Ca
27
224
55
111
86
478
56
808
90
177
95
190
98.2
714
127
545
2.0
120.0
90
474.4
41
43
Mg
30
268
56
92
28
222
32
538
23
49
20
100
65.7
1950
28
119
2.6
255.2
37
196.9
1
4.6
Na
40
799
57
192
28
152
161
3550
319
561
370
725
2040
2560
110
310
25.9
14,948
400
1439.0
2
32
HC03
265
203
284
395
378
310
189
49
165
317
575
465

6940
372.3
120.5
-
1.5
376
322.6
123
103
So4
17
1388
90
299
31
311
250
7680
24
159
155
1590
1150
415
285
3856
21.6
8489.5
400
1703.2
<4
66
Cl
6
1210
118
246
37
1318
110
1116
605
1020
355
305
2400
9470
64
303.9
34.0
18,694.2
380
1733.5
5
26
No 3
5
162
<4
123
--
—
~
—
—
—
1
0.5
10.2
25
7
5.1
0.4
1200.7
3.1
35.4
2.1
2.0
TOS
340
4310
560
1320
396
2630
798
13,856
1226
2283
1285
2960
5876
47,355
816
8874
144
45,350
1560
6338
124
318
TOC












119
12,962


14.8
338




 B-Before
 A-After
 C-Contaminated
UC-Uncontaminated

Al1 analysis in mg/1
                                            1-4

-------
1.1  HYDROLOGIC CYCLE
Ground water is part of an endless cycle of water recirculating from the earth
to the atmosphere  and  back  by  evaporation  and  transpiration  and  then precipi-
tation.  Water  on the earth exists either  as  lakes,  rivers,  icecaps,  shallow
fresh  ground  water, deep  saline  ground water, or  oceans  (Figure 1-1).   The
latter two categories, deep  saline waters  and  the  ocean, comprise the  bulk of
the water.   Deep saline ground waters, in general,  have been  isolated from the
biosphere  for  thousands  to millions of  years.    Some fresh  meteoric  ground
water may have been isolated for hundreds or thousands of years.   Isolation of
this ground water  attaches  a much  longer  time  element to the hydrologic cycle
than  is  normally  considered.   This  point  is  important in  understanding  the
role of hydrology  in geology.

Ground water  and  surface water do  not  occur as separately  and  distinctly as
they are commonly  treated.  Man is most familiar with surface water because he
can directly observe  it  everywhere.   Anyone can be  aware of the variation in
quantity and quality  of  surface water.   The problems of development and con-
servation  of  surface  water  can be readily  appreciated by   laymen.   However,
ground water passes out  of direct contact with man's senses.   Partly  because
of specialization  and  partly because  of the  large  differences between  surface
water and ground water environments, the two are often treated as separate and
distinct.  However, they are one hydrologically interconnected system.

The part of the  hydrologic  cycle  which  is  the  primary concern of this  section
is  the fresh meteoric ground  water  component.    It  is  this component  that
furnishes  potable  water,  and  is  the  component most  easily  polluted .by man's
disposal activities.

1.2  HYDROLOGIC PROCESSES OF GROUND WATER FLOW
Ground water  flow  in  an  aquifer  is  controlled by the  physical  laws of fluid
flow and the  geology of the aquifer  within which  flow occurs.  For simplifi-
cation,  this  section  addresses  the  movement  of  fluid in  an  ideal  aquifer
rather than a real, heterogeneous, anisotropic  geologic system.

An aquifer is a  water-bearing  unit  having  a porous or fissured framework that
permits water to  move through  it under natural  conditions.   In  this section,
                                      1-5

-------
                 For motion water from
                    sediment compaction
Figure 1-1.  Hydrologic  Cycle.   Nearly all  water  on or in the Earth
             is  being  recycled, whether  it  be  in  surface water  bodies,
             meteoric  ground waters, or  deep  formation waters (Modified
             from  Brown  and Others, 1975).
                                   1-6

-------
the  primary  focus will  be on formations  that  have  a  porous,  rather  than  a
fissure  matrix,  as  most aquifers  in  the region  are sedimentary  formations
which have predominately intergranular ground water  flow  rather than fracture
flow (Figure 1-2).

Geologic units that  typically have intergranular flow or a  porous  matrix are
generally  comprised  of  a  sand sized matrix.   These sands  were  deposited  in
fluvial, arid or  humid  fans,  intermontane, deltaic  marine,  terrace-gravel,  or
glacial  sedimentary  environments.   When  these sands  are  consolidated  (ce-
mented), the term sandstone is used.

Formations that typically have fracture or joint flow are limestones, basalts,
granites, metamorphic rocks, and consolidated sedimentary rocks  that have been
fractured.  In jointed units, primary porosity was either never  present (as in
granite), or diagenesis  (cementation) or subsequent deformation  has eliminated
most of the porous framework (as in a consolidated sedimentary rock).

A necessary  feature  in the hydrologic cycle  is  recharge  and  discharge to the
system.   Without  recharge,  the  aquifer  becomes drained of  water.   Without
discharge, the system becomes pressurized to  the point that  the  hydraulic head
of  the  aquifer is higher  than the hydraulic head  of recharge  waters  and  no
fresh water can be taken into the system.

A recharge zone  is the  area in which the aquifer receives water.  The hydrau-
lic  head of  the  recharge water must be greater  than  that of  the water in the
aquifer  (see  Section 1.2.1.1).  Often this  zone  represents  a topographically
higher section of the  aquifer.   Recharge  is  either by infiltration of surface
waters such as rivers and  lakes or percolation of precipitation  through a soil
profile.   In  the case  of soil  percolation of recharge  water, water moves
through an unsaturated  zone  (Figure  1-3).  This mode of recharge represents a
common method of recharging an aquifer.
                                      1-7

-------
                                                                 (d)
Ground-water flow in sand or sandstone aquifers is generally
intergranular (a) rather than through fracture porosity (d).
Permeability in the granular medium decreases where the sediments
are poorly sorted (b) or have been cemented (c) (modified from
Meinzer, 1923).
              Figure 1-2.   Flow in Porous Sediments

-------
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-------
Discharge zones  are areas where ground  water  is lost from the  aquifer;  that
is,  they  represent  the  areas of  lowest hydraulic  head.    Discharge  can  be
either  to  the  land surface  via  rivers, lakes,  springs,  and  seeps,  to  the
oceans  (e.g.,  submarine  springs  in Florida  and  Hawaii)  or to  other  aquifers
with lower heads.

1.2.1  Principles of Ground Water Flow
Porosity (0)  is  the percent void space or pore  volume in  a  rock,  sediment or
soil and is defined by the equation:
0 =
                                Volume of the void space
                            Volume of the total  porous medium
Total porosity is a measurement of the total  void space, regardless of whether
the  void  spaces  are  interconnected  or  whether they  are  totally  isolated.
Porosity is generally expressed as a percent.

Effective  Porosity  (ne)is the  measurement of the interconnected  pore space.
It  is  a  more realistic  measure  of the  pore space that  can be  utilized  in
ground water  flow.    Porosity varies with sediment  type, degree  of  sorting,
degree of  compaction,  and  degree  of  cementation.  In most unconsolidated sand
aquifers,  effective porosity and total porosity are approximately equal.

Hydraulic  Conductivity (or permeability)  is the ability  of  a  medium (rock,
sediment or  soil)  to transmit a  fluid.   Permeability  (k)  is  dependent on the
properties of the medium  (pore size, stratification,  sediment  size,  packing,
size distribution, and porosity).  Ground water hydrologists,  however, common-
                                      P
ly  use  either Meinzer  units  (gpd/ft  )  or  cm/sec  for permeability  units.
Typically,  values of  Meinzer units  are  determined by field aquifer tests.
Field  tests  measure transmissivity,  which  is permeability multiplied  by the
thickness  of  the producing interval of the aquifer.  Regardless of the methods
of determining coefficients of  permeability,  the unit  represents a rate (dis-
                                                                             o
tance/time).   The range  of  k  varies widely; measured values vary from 10
cm/sec for some clays  to  10   cm/sec  or  less  for well-sorted gravels (Table 1-
4).
                                     1-10

-------
                         TABLE  1-4
                     PERMEABILITY
105



10 8

10 4 10 3 10 2
1 1 1
10' 1 10-'
1 I 1
10 5 1Q4 TO 3
10 4 10 3 10 2
1 1 1
1,0 ^ 1,0 e 1,0 5
1,0 i 1 1,0-1
1,0
10-2
i
1,0 '
IP 1
1,04
1,0-2
FT./DAY
I 1
FT./MIN.
TO'3
10-'
io-4
GAL./DAY/FT.
1.0 i 1
M/OAY
1
FT./YR.
1,0 3
CM/ SEC.
1,0-3
1,0-1
1.02
1.0-4
1,0-2
TO'5
10-1
10-2
1,0 i
1,0-5
10-3 10-4 10-5
ID'6 lO-^ 10-8
10 -2 1p-3 1p-4
ID'3 1Q-4 10-5
1 1.0 -1 1,0 "2
1,0-e 1,0-7 irj-a
RELATIVE PERMEABILITY
VERY HIGH HIGH
MODERATE
LOW
VERY LOW
REPRESENTATIVE MATERIALS
CLEAN SAND
CLEAN GRAVEL AND SANO
AND GRAVEL
FINE SAND
SILT. CLAY AND
MIXTURES OF SAND.
SILT AND CLAY
MASSIVE CLAY
POROSITY %
30-40 30-40
30-35
40-50
45-55
REPRESENTATIVE MATERIALS
VESICULAR AND SCORIACEOUS
BASALT AND CAVERNOUS
LIMESTONE AND DOLOMITE
CLEAN SANDSTONE AND
FRACTURED IGNEOUS
AND METAMORPHIC
ROCKS
LAMINATED SANDSTONE,
SHALE. MUDSTONE
MASSIVE
IGNEOUS AND
METAMORPHIC
ROCKS
POROSITY %
1-50
< 20
< 10
< 5
-COMPARISON  OF  PERMEABILITY  AND  REPRESENTATIVE  AQUIFER MATERIALS.
                            1-11

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1.2.1.1  Darcy's Law
Ground water  flows from  areas  of higher  head  to areas  of  lower head.   The
total head is a summation of its gravitation, pressure,  and kinetic (velocity)
energy.   In  most  ground water systems, the  rate  of flow  is  sufficiently  slow
so that  the  kinetic component  is  negligible and, therefore,  not  considered.
The total  head  (h) in  an  aquifer  represents the  height to which  a  column of
water will rise in a well screened within the aquifer.

This  difference  in head  (Ah) represents  a loss  of energy to  friction  in the
system.   Darcy,  in 1856,  observed that  ground  water  flow (q)  through  a  unit
area  (A)  was  proportional  to the energy  loss (Ah), and to the coefficient of
permeability  (k),  but  inversely  proportional  to the  distance between  head
measurements (length of flow path, AL).  This relationship is known as Darcy's
Law and is represented quantitatively as:

                        q = kA Ah
                               AL

Figure 1-4 graphically demonstrates this relationship.

Nearly  all  other  ground  water flow  equations  are based  on this basic  flow
equation.  The equation does have certain limitations  or constraints  that  need
to be  mentioned.   Darcy's Law is  valid  only for  low  velocity, laminar ground
water flow.  Laminar flow can be characterized as the  movement of water parti-
cles  along  parallel,  non-intersecting  flow  paths.   Ground  water flow  in  a
sedimentary, porous  rock is generally  laminar  and not turbulent.   Turbulent
flow  (high-velocity  flow with  erratic  flow velocities,  flow  directions,  and
intersecting flow  paths) can occur in highly permeable,  fractured rocks (e.g.,
karstic limestones) or  in  close  proximity to high-discharge  water wells where
head differentials are extreme.  Darcy's Law is not applicable under  turbulent
flow  conditions or higher laminar flow velocities (Davis  and  Deweist,  1966).
Turbulent flow, and non-Darcian laminar flow would not be expected in sedimen-
tary media with intergranular porous flow.

The average  velocity  of  a  ground  water particle in an aquifer can  be deter-
mined by the equation:
                                     1-12

-------
                         Datum Z = 0
Figure 1-4. Darcy Tube.   Ground water flows from areas of
            higher head  to areas of lower head and conforms
            to Darcy's Law
                          (Q = KA
                                     Ah
                               1-13

-------
                        V = q/Ane = Ki/ne
where:

                        V  = average velocity
                        i  = Ah/Al
                        ne = effective porosity as a decimal fraction

This  equation  (Lohman, 1972) is  derived  by dividing Darcy's  Equation  by the
cross  sectional  area  (A)  and  the  effective  porosity (ne).   Though dividing
Darcy's equation  by (A)  alone will give  a  dimensionally  correct  answer (L/T)
for  velocity (Darcian velocity),  it  will  not  give the  correct  average flow
velocity until effective porosity is divided through the equation.  An example
will  illustrate the need to account for porosity.  Flow through a porous media
is comparable to flow  through a pipe or conduit.  If, for a given discharge, q
the  available  flow is reduced,  then the  velocity of the  fluid will  increase.
This  can be  seen mathematically as:

                        V = q/Ae

where:  Ae = available flow area

For  ground water;  Ae is analogous  to  Ane (the  effective  cross-sectional flow
area).  Flow velocities may be needed to calculate mass transport over geolog-
ic time or  to calculate the rate  of  possible contaminant migration  from dis-
posal sites.

1.2.1.2  General Ground Water Flow Direction
Steady-state ground  water  flow  must follow the  principle of  the conservation
of mass.  If we  consider  ground  water flow through  a unit element in an aqui-
fer,  then  the mass  inflow rate  must  equal  the  mass outflow  rate,  plus any
change  in mass storage capacity.   A change  in  mass  storage  capacity results
from  the compressibility of  the  aquifer matrix  and  the  water.  If the storage
term  is  negligible, then flow into and out of an element  has  to remain con-
stant.   As   stated earlier,  ground water  flows from areas of  high  hydraulic
potential to areas of  lower hydraulic potential.  In the Darcy tube  (Figure 1-
                                     1-14

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4), the focus of points of equal head result in equipotential  contours (in two
dimensions)  or  equipotential  surface (in three dimensions).   Under  isotropic
conditions,  ground water  flows perpendicular to  this  equipotential line  or
surface.   By knowing  the shape of  potentiometric surface, the direction  of
ground water flow  can be determined.  Potentiometric surface  maps are  a  com-
monly  used  tool  by hydrogeologists for  determining direction  and   rates  of
movement of  ground water in a  geologic unit.  Figure 1-5  is  a potentiometric
surface map  for the Goliad Sand in South Texas.

1.2.2  Aquifer, Aquitards, and Aquicludes

1.2.2.1  The Aquifer, the Matrix in which Ground  Water Flows
Permeability  and  transmissivity  control  both  rate and  direction  of  ground
water  flow.    The  geology controls  these  parameters  at  several  different
scales.  Table 1-5 presents the definitions of terms applicable to  aquifers.

Ground water flow between recharge  and  discharge  zones will  be either under
unconfined conditions  (water  table), under  confined conditions (artesian),  or
under  semiconfined conditions  (Figure  1-3).   For  an unconfined aquifer,  the
upper  boundary  of  the saturated zone is the water  table.   The water table  is
defined as a free  surface over  which pressure  is zero (atmospheric pressure);
therefore, the  hydraulic  head of the water  table is equal  to the elevation of
the  table.   Below the water  table,  pressures are  greater than  zero,  while
above  it  (in the unsaturated  zone), pressures can  be less  than  zero.  In the
case of an unconfined aquifer,  the elevation of the water table and subsequent
changes in head are  commonly controlled  by the  topography.   The  water table
often  mimics the  topography  in a  subdued  fashion;  therefore, ground  water
tends  to follow the topography.  Recharge  occurs  at  the  high  points and  dis-
charge at  the low  points.

In a confined system  (an  artesian  aquifer), the  hydraulic head is  a summation
of the gravity head  and the  pressure head.   The   potentiometric  surface (as
measured in  a well  penetrating  the  aquifer) is above the elevation of the top
of the aquifer.    The  potentiometric surface and  the subsequent ground water
flow does  not  necessarily follow the overlying topography  but rather is  con-
trolled by the stratigraphic dip of the aquifer.
                                     1-15

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Number indicates altitude of water level


       Water level contour
      Datum mean sea level
  Figure  1-5.  Approximate Altitude of Water Levels in  Wells Completed
                in  the Goliad Sand,  1977-1978
                                1-16

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                                  TABLE  1-5

                             AQUIFER DEFINITIONS
AQUICLUDE OR CONFINING LAYER - a geologic unit or layer that forms  an upper or
lower boundary  to a ground  water  flow system through which  only  significant
ground water flow occurs.

AQUIFER - a geologic unit that can store and transmit water.

AQUITARD  OR  LEAKY CONFINING LAYER -  a geologic  unit or layer that  can  store
ground water and also transmit it slowly from one aquifer to another.

CAPILLARY FRINGE  -  the zone at the bottom  of  the  vadose  zone and  immediately
above  the water  table  surface,  where  water is  drawn  upward  by  capillary
forces.

CONFINED  OR  ARTESIAN  AQUIFER  - an aquifer that  is  overlain by  a  confining
layer and, if the overlain aquifer is  saturated,  then the water in  the aquifer
is under  artesian pressure.

PERCHED AQUIFER  - an aquifer that is  usually  not  very large and  exists  as a
lens of saturated sediments  resting on an  impermeable layer located  above the
main water table.

POTENTIOMETRIC LEVEL - the  level to which  water  would rise in a tightly cased
well from a given point  in  an  aquifer.  This level varies vertically through-
out an  aquifer  because it is the response  to  the  sum of  the  forces  acting on
the  system  including gravitational,  overlying pressure heads,  and  confining
pressure  heads.

POTENTIOMETRIC  SURFACE  - an  imaginary surface representing  the ground  water
head  in a confined  aquifer which is  expressed  by  the  level to  which  water
rises in  a  tightly cased well.  The  term  "piezometric" was  used  in the  past
although  potentiometric is now preferable.

SATURATED ZONE  - the  portion  of the  geologic media  in  which  the  voids are
filled with water at greater than atmospheric pressures.

UNCONFINED OR  WATER-TABLE AQUIFER -  an aquifer that does not  have  an  upper
confining  layer  and  extends  from  the  ground  surface to  a  lower  confining
layer, or in which the potentiometric  surface is  below any overlying  confining
bed.

UNSATURATED OR  VADOSE  ZONE  -  the  portion  of the geologic  media in  which the
voids are filled with water at less than atmospheric pressures and  air.

WATER-TABLE  -  a  special  potentiometric  surface  which  occurs  in unconfined
aquifers  and represents the upper surface of the  ground water in the  saturated
zone.  The pressure at this surface is equal to that of the atmosphere.
                                     1-17

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The aquifer  is confined by  overlying  and  underlying lower permeability  beds
(aquitards).   It is important to note that  even though  the aquitard  causes the
artesian  conditions,  it can transmit  significant  quantities  of water  if the
bed is  relatively  thin, has a  large cross sectional area,  and  has  a signifi-
cant head  differential  across  the bed.  For example, a clay  with a thickness
of  100  feet  and  a  permeability  of 0.1  millidarcy and  a  hydraulic head  of
differential  of  10 feet will  transmit  1.84  x  10ฐ gallons of water  each  year
for each  square  mile of aquitard (David and DeWiest, 1967).   In the Houston,
Texas area,  Jorgensen (1975) estimated that  up to 22 percent of the 500  mil-
lion gallons of ground water produced daily resulted from  clay drainage.  Even
though clay  has a  low permeability,  the total  flow may  be quite large because
of  the  large  cross   sectional  area  in  which  flow occurs.   This  concept  is
important  in recharge-discharge relationships for  an  aquifer  and  where  thin
clay units separate large waste lagoons from  an aquifer.

Permeability of Sediments
The permeability  of  sediments  is particularly dependent  on  (1)  porosity, (2)
grain  size,  and (3)  sorting of the component grains.   Figure 1-6  shows the
relationship  between  permeability and  porosity.   Permeability  trends plotted
against  natural  grain-size  populations  are  compiled in  Figure 1-7.   Though
there is  considerable spread,  sand  populations with  a  median  in the very fine
sand size  have permeabilities  of  tens  of meinzers,  and  permeability increases
logarithmically  to thousands  of  meinzers for  very coarse sand  populations.
Other factors,  including horizontal stratification  and depositional environ-
ment, can  also affect permeability.

Sand-Body  Geometry
Geologic  formations   too  often  are  thought  of  as  being either aquifers  or
aquitards.   A  geologic  formation,  however, represents  a mixture of   lithologic
units that are genetically related.  A  fluvial system  is composed  of channel
sands,  crevasses,  sands and silts,  and overbank  muds.   A  deltaic  system may
consist  of  several  sand and  mud  units from  different   modes  of  deposition.
Because of this heterogeneous nature of a formation, an aquifer may  often have
an  internal   geometric  framework  of  high-permeability   sands  within  low-
permeability muds.   This  concept  is  important  in  determining  potential  pollu-
tion migration in many  aquifers.
                                     1-18

-------
TEXTURE
10000 1	r
 5OOO
 IOOO


 5OO
f_ IOO

Ij
03  50

Ul

a:
LiJ
O,  10

O
  O.I
DOGGER
 BETA
'X;
                                  IOOO


                                  500
                                   100


                                   50
                                    I


                                   0.5
                                   O.I


                                  0.05
   0    5    10   15
                                  0.01
                                            UPPER
                                         CARBONIFEROUS
                     20   25   30    05    10

                       POROSITY   (PERCENT)
                                                  is   20   25   30
  Figure 1-6-   Plots of Permeability Versus  Porosity
                (From Fuchtbauer,  1967)
                                1-19

-------
10,000
 1000
 o
 ฃ
                                         x VERDIGRIS a VALLEY (OKLA)
                                         + ARKANSAS R. VALLEY(OKLA)
                                         • MISSISSIPPI R. VALLEY  (ARK)
                                         o LABORATORY SAMPLES
                                         a LOWER MISSISSIPPI R VALLEY
       sty vf
                                                             sd * jrov
                             GRAIN SIZE (0)
   Figure  1-7.  Plot of Permeability Versus Grain Size
                 (Raw Data  from Bjorklund  & Brown, 1957;
                 Newcome &  Page,  1962; Smith &  Others,  1964,
                 Sniegocki,  1964)
                                  1-20

-------
The geometry  of  the aquifer can be predicted by the depositional  model.   The
initial deposition  of  the  genetically related unit will dictate  the  orienta-
tion of the sand and mud bodies.  Fluvial sands  and distributary channel  sands
characteristically  will  be dip-oriented.   Strandplain, delta-front  sands  or
barrier-bar sands  characteristically will be  strike-oriented.   Braided  stream
and fan deposits will form more continuous sand  sheets  in comparison with mix-
load meandering stream channel or deltaic distributary  channel  fills.

In the Houston area, major dip-oriented sand trends in  Plio-Pleistocene  depos-
its stack one on top of the other.   Similarly, the  strike-oriented sands  along
the Coast  from land  surface  to the  base of the  Alta Loma Sand  (1,000  feet
below  land surface)  are  also  stacked  (Kreitler  and others,  1977).  Fisher and
McGowen  (1967)  observed  a  similar phenomena  in the deep Wilcox  Group.   This
stacking of  sands offers  a different  model for an  aquifer.    It  is  possible
that there is better  vertical  continuity through a number  of  overlying  forma-
tions  than  there  is  horizontal continuity  within one  horizontal  formation.
The geometry  of  sands and muds in a  stratigraphic package  can result in com-
plex,  large scale aquifer  heterogeneities.

Structural Features
Faults are another type  of boundary that control  the.  geometry of an aquifer.
The effectiveness  of  a fault  as a low-flow zone is  dependent  on  the  ratio of
sand thickness  to fault displacement  and  the presence  of  fault  gouge  within
the fault  zone.   A  fault  with small  displacement in  a thick  sand will  be a
less  effective  barrier  than   that  same  fault  completely  displacing  several
thinner sands.  Fault gouge may reduce permeability within the fault and  cause
the  fault  to act  as a  low-permeability  boundary,  even  though the  fault-
displacement/sand-thickness  ratio   is  relatively   small.    Bed  displacement
results in a change in transmissivity, whereas fault gouge results in a change
in permeability.

The impact of faulting on the  aquifer  hydrology is  dependent  on  the geologic
style  of  the  area.    Faults  in the  Gulf  Coast region are  typically  growth
faults formed  syngenetically  with  deposition.  Density  of  faults may be very
high in  this  region where thin sand beds are intercalated  with muds.  Faults
                                     1-21

-------
in these  sediments easily  offset  sand  beds, and  the  higher mud content  may
form a  gouge along the faults.   In  the  western interior basins, such  as  the
Paradox or the San Juan Basins, the faults are basement-derived  and,  in gener-
al, post-depositional.   Fault displacements  are greater  than in the  shallow
Gulf Coast sequences, but  sand beds  are  thicker and  percent  displacements  are
probably less.  Faulted sands are cleaner, with more  sand  and less mud; there-
fore, they probably have less fault-gouge developed in  the fault  zone.   Faults
in Gulf  Coast aquifers may  act  as better low-flow boundaries than  faults in
interior basins  of the  arid West.   Faulting  contemporaneous  with deposition,
such as Tertiary growth faults in the Gulf Coast or faulting  in  the  Pennsylva-
nian section  of  north Texas,  can  cause thickening  of sands  on the down-thrown
side (increase of  transmissivity) or cause different  facies  to be deposited on
either  side  of the fault  (differences  in permeability).   In most  instances,
faulting in  the Texas  Gulf Coast area  is  not  an  important  consideration in
pollution migration since  faults usually  do  not displace  the thick  clay units
which protect the  regional aquifer.  However, in the  competent rock  areas,  for
example in the  Balcones Fault zone  in Texas, pollution migration along fault
zones has been documented.  In these areas, the permeability of  the  fault zone
has been increased by percolating  surface water, and contaminant transport is
rapid.

1.2.2.2  Aquicludes and Aquitards
Perhaps the  single most common error that the uninitiated make  in relation to
ground water hydrology  is related to aquicludes and aquitards.   An aquiclude
is a  theoretical  body  that  acts  as  a perfect  no-flow barrier  (i.e.,  it pre-
cludes the transmission of water  or  pressure).   An aquiclude is a useful tool
in the  initial  analysis of a  ground  water system in  that it  allows  the inves-
tigator to make simplifying assumptions  for  his ground water model.   It must
be realized  that such a perfect barrier is unlikely to  exist  in  any  area under
investigation.   An  aquitard  is  the realistic unit  that  limits or  retards
movement of  ground water  or transmission of pressure in a  given  direction.
Once the theoretical model has been constructed and the field testing phase of
a project has  been completed,  the  aquiclude  must be  modified to represent the
conditions found in the field and becomes an aquitard model.
                                     1-22

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1.3  GROUND WATER RESOURCES
According  to  the  United  States Geological  Survey (USGS;  1970),  the  United
States used  1.4 x  10*  itr/day  of water.   Of  this total, 57 percent  was  used
industrially and  35 percent  for irrigation.   For  the entire country, 81  per-
cent  of  the  water came  from  surface supplies,  and  19  percent  from  the
ground.   However,  in the  17 western states, 46  percent of all public  water
supplies came from  the ground.  In EPA Region VI,  the  following percentages of
public water supplies coming from ground water  are:   over 40  percent in Okla-
homa,  over 50  percent  in Arkansas,  over 70  percent in  Louisiana, over  80
percent in Texas, and over 90 percent in New Mexico.

1.3.1  Description  of Major Aquifer Systems in EPA Region VI States
The following information, most of which is summarized from the National  Water
Summary  (USGS,1984),  briefly discusses the aquifers  of  each  state  and  their
characteristics.

1.3.1.1  Arkansas
Six major  aquifers  supply most of the ground water used in Arkansas (Figure 1-
8).  The aquifers are (1) Alluvial aquifers, (2) Cockfield aquifer, (3) Sparta
Sand aquifer, (4) Wilcox aquifer, (5) Nacatoch Sand aquifer, and (6)  the Ozark
aquifer system.

Alluvium
The alluvial deposits, which are the principal source  of  water for irrigation,
blanket much of  eastern Arkansas, the  Red  River Valley in southwestern Arkan-
sas, and  isolated  areas  along  the  Arkansas River in  the  interior Highlands.
The  alluvium  is composed of  coarse  sand and gravel  at  the base  that grades
upward to  silt  and clay  near  the  surface.   Recharge  is from  stream loss and
local  precipitation.   In parts  of  Chicot, Desha, Lincoln, Monroe,  and White
Counties,  the water contains  as  much  as 3,750 mg/1 of dissolved solids, which
makes  it   unsuitable  for  irrigation.   The saline water is believed  to  have
migrated upward  from underlying, saline water-bearing beds through  faults or
abandoned  oil test  wells.  A similar problem exists  in the Red River alluvium
in parts of Miller  and Lafayette Counties.
                                     1-23

-------
 EXPLANATION



 fci;^j   Alluvial aquifers



 j^jfl   Cockfield aquifer



 ^^   Sparta Sand aquifer



 f"j|   Wilcox  aquifer



^^J   Nacatoch Sand aquifer



I	    Not a principal aquifer


       Ozark aquifer system - Present only in

       the subsurface in Arkansas
50
 i
100 MILES
 (Adapted from U.S.G.S.. 1985)
                             Figure 1-8.   Principle Aquifers in  Arkansas
                                                  1-24

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Cockfield
The Cockfield aquifer is at or near the surface of the Coastal  Plain of south-
eastern Arkansas.   The  aquifer,  which consists of interbedded  fine to medium
sand,  clay,  and  lignite,  is  as much  as  400 feet thick  in Chicot  and  Desha
Counties.  The  water generally is suitable for most  municipal  and  industrial
uses.

Sparta Sand
The Sparta Sand aquifer is the principal  source of water for public  and indus-
trial supplies in much of southern and southeastern Arkansas.  The aquifer also
is being tapped increasingly  for  irrigation in Arkansas  County.  The Sparta is
composed of massive fine to medium sands  that  contain interbedded clay lenses,
and  is  as  much  as 800 feet thick.   North of  about latitude 35ฐN,  the Sparta
Sand becomes  part of a  thick sand sequence known as  the Memphis  Sand.   The
Memphis Sand commonly is not used in Arkansas  as  a source of water because the
water generally contains high concentrations of iron.

WiIcox
The Wilcox aquifer occurs throughout most of the  Coastal Plain in Arkansas but
is a major source of  water  only  in northeastern  Arkansas where it is known as
the  "1,400-foot  sand."    It is  primarily  used for public and  industrial  sup-
plies.   In  southwestern  Arkansas, the unit is composed  of  fine  sand and silt
and does not yield  significant amounts of water.   The Wilcox aquifer contains
fresh water to a  depth of 1,500 feet below land surface in Crittenden County.

Nacatoch Sand
The  Nacatoch  Sand aquifer underlies  the  Gulf Coastal  Plain part of Arkansas
but contains fresh  water  only in  parts of the northeast and southwest.  It is
used primarily  for  public and industrial  supplies in  Clay,  Greene, Randolph,
and  Lawrence  Counties in the  northeast  and in Nevada,  Hempstead,  and Little
River Counties  in the southwest.   However, water-level  declines of more than
40 feet  have been  noted at  Prescott  in  Nevada  County  as  a result  of  large
municipal withdrawals.
                                     1-25

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Ozark
The Ozark  aquifer consists primarily of  dolomite,  sandy dolomite, and  sand-
stone  and  is  the only  significant  aquifer system,  except  for the  Arkansas
River alluvium  in  the  Interior Highlands.   It  is  used in northern  Arkansas in
an area  from Benton  and Washington Counties  to  Randolph and  Lawrence  Coun-
ties.   The system  includes the  Roubidoux Formation  and  the  Gunter  Sandstone
Member of  the  Van Buren Formation, which do not crop out in  Arkansas.   These
strata are  the principal source of  ground  water  in the northern  part of  the
state.  The  Roubidoux  is 100  to  250  feet  thick and is present at depths  rang-
ing from 600 feet at the Arkansas-Missouri state  line  to about  2,300 feet at
the southern limits of  the  area  of use.   The  Gunter Sandstone Member is  about
50 feet  thick  and is  300  to 600  feet  below the "Roubidoux  Formation.    The
massive dolomites  between these aquifers do not yield water.

1.3.1.2  Louisiana
The principal aquifers  in  Louisiana, as shown  in  Figure 1-9,  are (1)  Alluvial
aquifers,  (2)  Pleistocene aquifers, (3)  Pliocene-Miocene aquifers,  (4)  Cock-
field and Sparta aquifers, and (5)  the Wilcox-Carrizo aquifer.

A1luvium
The alluvial  aquifers underlie the  floodplains  of the Mississippi,  Red,  and
Ouachita River  valleys.   The  alluvial deposits typically  consist of  a confin-
ing layer of clay  and silt that overlies sand  and gravel.  The aquifers gener-
ally  thicken southward;  the base of the  aquifer  is  about 100 feet below land
surface in the  north  to 250 to 450 feet below land surface  in the south.  The
Mississippi  River  alluvial aquifer is the largest yielding unit.  The alluvial
aquifers are not  developed extensively,  but   the  water is  ideal  for irriga-
tion.  Slightly saline water  in local areas  in the  Red and  Mississippi  River
valleys may  be  the result of pollution by oil-field brines.

Pleistocene Aquifers
The  Pleistocene aquifers  are principal  sources  of  fresh  water  in  central,
southwestern,  and  southeastern Louisiana.  In central  Louisiana,  the terrace
aquifers are important, though of  limited  potential.  The aquifers  range in
depth from 50 to 200 feet.
                                     1-26

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 EXPLANATION




 |i::i:3  Alluvial aquifers
      Pleistocene aquifers
      Pliocene-Miocene aquifers
      Cockfield and Sparta aquifers
      Wilcox-Carrizo aquifer




      Areas where no freshwater

      occurs at any depth
(Adapted from U.S.G.S.. 1985)



                       Figure  1-9.
ฃ>p
!Xv*"ป
a&:
                                                                         50
                                                                                       100 MILES
                                      Principal  Aquifers in  Louisiana
                                              1-27

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The Pleistocene Chicot aquifer, which is the principal  aquifer in southwestern
Louisiana and is the most intensively pumped aquifer,  provides over 50  percent
of the total ground water withdrawals in Louisiana.  Aquifer depths range from
about 50 feet in  northern outcrop  areas  to  800  to  1,000 feet in total  coastal
area.  To the north,  the  water is  hard  but  is suitable for irrigation; to the
south, deeper  sands yield soft water of excellent quality  for  public-supply
use.

In southeastern Louisiana, the  Pleistocene  aquifers range  in depth from a few
hundred feet to  more than 1,000 feet and contain freshwater to  depths of 700
to 800 feet in  the southern part  of the  area.   Principal  individual  aquifers
are  the  "400-foot"  and  "600-foot"  sands  at  Baton  Rouge,  the  Gonzales-New
Orleans aquifer  (principal  source  in New Orleans), and  the  upper Ponchatoula
aquifer.

Principal problems  with  the  Pleistocene aquifers are   (1)  the  limited  produc-
tion capacity of the terrace aquifers locally, (2)  local saltwater problems in
the Chicot  aquifer,  and  (3)  saltwater encroachment  (in the "600-foot"  sand at
Baton Rouge and in the Gonzales-New Orleans  aquifer).

Pliocene-Miocene Aquifers
The Pliocene-Miocene aquifers form part  of a large  artesian basin in the west-
ern part of the  Gulf Coastal  Plain and  supply potable water to many towns and
cities.   The  Pliocene-Miocene aquifers  include the  Evangeline,  Jasper,  and
Catahoula aquifers  of  central  and  southwestern  Louisiana;  the  sands below the
"600-foot"  aquifer  in the Baton Rouge area; and deeper sands in southeastern
Louisiana.

In the Evangeline aquifer in southwestern  Louisiana,   freshwater  extends to a
maximum depth  of about 2,200  feet;  in  the  underlying  Jasper  aquifer, fresh-
water  extends  to about  3,400 feet.  The total sand   thickness  available for
development ranges  from about 100 to 1,000  feet.   In southeastern Louisiana,
individual  sands  tend to be thicker and  average yields greater than in other
areas.  Depth to  the base of the freshwater section in southeastern Louisiana
ranges from about 2,000 to 3,400 feet.
                                     1-28

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The  principal  problems  pertaining  to Pliocene-Miocene  aquifers are  locally
high fluoride  concentrations  (greater  than  2 mg/1), dark color, depletion  of
artesian head  in intensively pumped areas,  and local saltwater encroachment.

Cockfield and  Sparta
The  Cockfield  and  Sparta are  important  aquifers  in northern  Louisiana  -  the
Cockfield principally in the northeastern and the Sparta  in  the  north-central
parts of  the state.  In much  of  the  area  where the Cockfield contains  fresh
water,  it  underlies the  alluvial  aquifer  and  generally  yields  softer  water
than that  yielded  by the  alluvium.   Water  in  the  Cockfield typically  has  a
color level that may be objectionable  for public supply.

The  areally  extensive  Sparta  aquifer is  the principal  source  of supply  in
north-central  Louisiana, where it  is  as  much as 700 feet thick.   Fresh  water
in the  Sparta  aquifer  is  present  to depths  ranging  from a few hundred feet to
about 1,000  feet.   The  water  generally  is soft, and  iron concentrations  are
typically less than 0.3 mg/1 in the deeper  sand units.   The  principal  problems
of the  Sparta are  declining water  levels  (annual  declines  range from 1 to  3
feet),  and saltwater encroachment (in  the Monroe area).

Wilcox-Carizzo
The  Wilcox-Carizzo is  the  most  important  and areally  extensive  aquifer  in
northwestern  Louisiana.   However,  the aquifer sands  are typically  thin  and
fine, which  restricts well  yields.    Water  quality is somewhat variable  but
generally suitable for domestic and public-supply use.

1.3.1.3  New Mexico
New  Mexico's  most  important   aquifers include  (1)  Valley-fill  aquifers,  (2)
Basin-fill  aquifers,   (3)   Sandstone   aquifers,  and (4)  Limestone  aquifers.
Their areal distribution is depicted on Figure 1-10.

Valley-Fill Aquifers
The  valley-fill  aquifers consist mostly  of  alluvial  and  terrace  deposits that
border  the  major rivers  in  the  state.  The most important  are  located  along
the  Rio Grande,  which  flows north-south  through  the center  of the  New Mexico,
Rio  Chama  in the  north,  the  San Juan River  in  the northwest,  and  the  Pecos
                                     1-29

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 EXPLANATION
p*jj  Valley-fill aquifers

||||i|  Basin-fill aquifers

[;.;.vj  Sandstone aquifers

yffl(  Limestone aquifers

      Not a principal aquifer
CAdapted from US.G-S, 1985}

                        Figure  1-10.
                       50
                                  100 MILES
Principal  Aquifers  in New  Mexico
     1-30

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River  in the  southeast.    These  aquifers generally  are less  than 200  feet
thick.   The valley fill  along  the  Rio  Grande and Pecos River  provides  large
quantities of water to wells.  Wells drilled  in these areas  commonly penetrate
deeper  aquifers  to increase yields.  The water generally  is fresh,  although
slightly  saline  water may  be encountered  locally  in the aquifers.  Water  is
discharged  from  the  aquifers by  wells,  spring flow, evapotranspiration,  and
seepage  to the rivers.

Basin-Fill Aquifers
The  basin-fill   aquifers  are comprised  mostly of  materials that  have  been
eroded  from  the  mountainous areas  and  transported  by either streams  or wind
into  structural  or topographic basins.   Two  very  distinct basin-fill  areas
occur  in  New Mexico.   One is the  deep troughs and  intermontane  valleys of the
Basin  and  Range  province (filled  with material commonly called  bolson depos-
its),  and  the  other is in  the  Great  Plains province  where  a broad  expanse  of
alluvial  fans  and other  stream and wind-blown  deposits  collectively  comprise
the  High Plains  aquifer.   The thickness  of basin-fill deposits  in  the  Rio
Grande  valley may be  as  much as 20,000  feet, but in  most areas,  the  deposits
range  in thickness from  only  a few  hundred  feet to 2,000 feet.   The  water
contains  more  than  1,000 mg/1  dissolved  solids  generally  below  a depth  of
3,000  feet.  The High Plains aquifer, located along  the eastern border of the
state,  has  a  maximum  thickness  of  about 400  feet and an average  thickness  of
about  200  feet.    Water  from this aquifer generally contains less  than  1,000
mg/1  dissolved solids.   Discharge from the basin-fill  aquifers  occurs mostly
as a  result of pumpage  for  irrigation and  municipal  supplies,  of infiltration
to the valley-fill aquifers, and of underflow to Texas.

Sandstone Aquifers
The sandstone aquifers  are  located  in the  San Juan  Basin part  of the Colorado
Plateau  province.   The  total  of  sedimentary rocks  in  the  basin probably  is
more  than 15,000 feet;  these aquifers are  a  series  of hydraulically intercon-
nected sandstones.  The  series  of  sandstones  are  exposed around the perimeter
of the basin  and  are  recharged by precipitation  and ephemeral  streams.   The
quality  of  the  water  in  the sandstone  generally  is  fresh  near  outcrop  areas
and for  some distance  down  the  flow path but  may  deteriorate with depth  as it
flows  toward discharge  areas in the  northwestern part  of the basin.   Some  of
                                     1-31

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the ground water in the aquifers discharges to the San Juan River,  some evapo-
rates, and some discharges to  the  Rio Grande.   Much  of the water in the lower
sandstones may  move upward through partially impermeable  confining  layers  to
other aquifers  or  to the land surface in the central  part of  the  basin where
it evaporates or  is used by plants.  Water  is  also  withdrawn  for  industrial,
public, agricultural, and rural supplies.

Limestone Aquifers
The  limestone  aquifers are  a  major source  of  water in the southeastern  and
central parts  of  New Mexico near  the Pecos  River and in  the  western  part  of
the state  near  the Rio San Jose.  The aquifers are  productive in  these areas
because of the secondary solution and fracture permeability that has developed
in the  rock.   Primary  recharge  to these  aquifers   is  from  infiltration  of
precipitation,  from surface water  from  tributaries   of  the Pecos  River,  and
from  the  Rio San  Jose.  Discharge  from  the aquifers   is mainly  from  wells  and
springs.

1.3.1.4  Oklahoma
Figure  1-11  shows the  principal  aquifers  in  Oklahoma.   These  include  (1)
Alluvial/terrace deposits,  (2) High Plains  aquifer,   (3) Antlers  aquifer,  (4)
Rush  Springs  aquifer,  (5)  Dog Creek-Blaine  aquifer,  (6)  Garber-Wellington
aquifer, (7) Vamoosa-Ada aquifer, (8) Keokuk-Reeds Spring  (Boone) aquifer,  (9)
Roubidoux  aquifer, (10)  Arbuckle-Simpson aquifer, and  (11) Arbuckle-Timbered
Hills aquifer.

A1 luvium
The alluvial aquifers  consist  of alluvium and  terrace  deposits of Quaternary
and  Tertiary age  along  the  major rivers  -  the Arkansas  (including  the Salt
Fork  Arkansas), the Cimarron,  the North Canadian, the  Canadian,  the Washita,
and the North Fork  Red Rivers.  These deposits generally extend from 1 mile to
as much  as 15 miles  from the rivers, and  their  thickness ranges  from a  few
feet  to  about  300 feet.   The  alluvium and terrace deposits  are  generally
unconfined and  consist of  sand,  silt, clay,  and gravel.   In some areas, over-
lying dune sand forms a part of the aquifer.
                                     1-32

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   EXPLANATION
        Alluvium and terrace deposits along major streams



        High Plains aquifer






        Antlers and Rush Springs aquifers                                             L	





        Dog Creek - Blaine aquifer






        Garber -  Wellington and Vamoosa • Ada aquifers





        Keokuk • Reeds Spring (Boone) aquifers





        Roubidoux aquifer





  ฃ$ฃ   Arbuckle - Simpson and Arbuckle - Timbered Hills aquifers





        Not a principal aquifer




	Boundary of aquifer uncertain




      (Adapted from US.G.S, 1985)




                             Figure 1-11.   Principal  Aquifers in Oklahoma





                                                   1-33
50
           100 MILES

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High Plains Aquifer
The  single  largest  source  of ground  water in  Oklahoma  is  the  High  Plains
aquifer,  which consists  of  the  Tertiary Ogallala  Formation and  associated
Quaternary alluvium and terrace deposits.   Saturated  thickness of  this  aquifer
ranges from a few feet to more than 500 feet.   This  aquifer  consists mostly  of
fine sand and  silt with lesser quantities of clay, gravel, and minor  beds  of
limestone and caliche.  Most of the water  from  the High  Plains aquifer  is  used
for irrigation, but it also is the principal  source  of domestic and  industrial
supply in the High Plains of Oklahoma.   The water is  suitable  for  most  uses.

Antlers
The  Antlers  aquifer  in  southeastern  Oklahoma contains  large quantities  of
water.   Due to  the greater  precipitation  and  the resulting  availability  of
surface water  in  the  southeastern  part  of  the  state, this  aquifer is not  used
to  its  full  potential.   The  water generally is suitable for  all  uses  but may
be saline at depth.

Rush Springs
The Rush Springs aquifer, a fine-grained sandstone in the  west-central  section
of the state, is used extensively for irrigation.   Water generally is suitable
for  all  uses.    In areas of  intensive  irrigation pumpage,  water levels  have
declined as much as 50 feet.

Dog Creek-Blaine
The Dog  Creek-Blaine aquifer in extreme southwestern Oklahoma  contains water
in solution openings  in  gypsum.   The water is  used  extensively for  irrigation
but it  contains  excessive quantities  of calcium  sulfate  (gypsum) in solution
that renders it unsuitable for drinking.  During the pumping season, drawdowns
may be  as much as  50 feet,  but  the aquifer  is  recharged  rapidly  by  surface
runoff that flows into sinkholes and solution openings.

Garber-Wellington
In  central  Oklahoma,  the  Garber-Wellington  aquifer is  the   principal water
supply for several  of the Oklahoma City suburbs.  The  aquifer generally  con-
sists of fine-grained sandstone, shale, and siltstone with a maximum thickness
of 900 feet.   Several water-yielding zones, which become  confined with depth,
                                     1-34

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are  present  in  the aquifer.   Water quality  generally is  suitable for  all
uses.   Local areas of  intensive  pumpage  have  caused drawdowns of  100  to  200
feet.   Excessive  pumpage  may cause upwelling of  brine,  which is  present  at
depth.

Vamoosa-Ada
The  Vamoosa-Ada  extends in a  band  from north  to  south in  east-central  Okla-
homa.  Aggregate  thickness of  water-yielding sandstone  ranges  from  100  to  550
feet.  Where  it is  near the land surface,  the aquifer is unconfined, but down-
dip  (to  the west)  the aquifer  is confined.  Most  withdrawals  from  this rela-
tively  undeveloped aquifer  are for public  supply  and  industrial  use.   The
water  quality generally is  suitable for all  uses in  the  upper part  of  the
aquifer but  becomes increasingly saline near the interface between the potable
and  saline  water  in the deeper confined part of the aquifer.  Excessive pump-
age  may  cause upwelling  of  this saline water.   Oil-field  brines  and  wastes
resulting from past operations have caused some local contamination.

Keokuk-Reeds  Spring (Boone)
In northeastern Oklahoma, the  Keokuk-Reeds Spring (Boone)  aquifer is a depend-
able  source  of water  where  it  is  near the land  surface.   The  Keokuk-Reeds
Spring  aquifer consists of  residual chert  and  cherty  limestone.   The small
yields  from  wells  preclude  any  large-scale  development of the aquifer  for
other  than  domestic purposes.   The water generally  is  suitable  for most uses
but  is hard  to  very hard.   Because of interconnecting sinkholes  and  cavern
development,  the  Boone has the potential to be  readily contaminated by surface
sources.

Roubidoux
Underlying  part  of the Keokuk-Reeds Spring aquifer  is  the  Roubidoux aquifer,
which  consists of fractured  dolomite that  contains several  sandy zones  and is
not  exposed  at the surface in  Oklahoma.  The  water  is  moderately hard  and is
the  principal public  and industrial water supply  in  Ottawa County in extreme
northeastern  Oklahoma.

Arbuckle-Simpson
In the Arbuckle  Mountain area in south-central Oklahoma,  limestone, dolomite,
                                     1-35

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and sandstone  units from 5,000 to 9,000 feet thick  form  the  Arbuckle-Simpson
aquifer.    The  aquifer  is  largely  undeveloped  and contains  an estimated  9
million acre-feet of generally very hard water in storage.

Arbuckle-Timbered Hills
The Arbuckle-Timbered  hills  aquifer  in southwestern  Oklahoma underlies  the
Lawton area.  Fluoride concentrations of up to 35 mg/1  effectively prevent any
widespread  use of the water for public supply.

1.3.1.5  Texas
Seven major aquifers supply most  of  the  ground  water used in  Texas (Figure 1-
12).  The  aquifers  are  (1)  Alluvium,  (2) the Carrizo-Wilcox,  (3)  the Edwards-
Trinity  Plateau,  (4)  the  Edwards  Balcones  Fault  zone,   (5)  the Gulf  Coast
aquifer, (6) the Ogallala, and (7) the Trinity Group.  There are also numerous
other minor aquifers  located throughout  the  state (Figure  1-13) which  are
important  sources of water for industries and municipalities in those regions.

Alluvium
The alluvial deposits which  are  considered major  aquifers in Texas  are  the
unconsolidated deposits  in structural troughs in Crane and Walker Counties and
the Seymour aquifer in  North  Central  Texas.   These  deposits generally consist
of  interconnected,  lenticular deposits  of  sand  and gravel  interbedded  with
clay and silt.   Recharge  is from stream loss and local  precipitation.  In West
Texas,  ground  water movement  is  toward  the  Pecos River Basin.   This  area is
susceptible to  pollution from  oil  and gas  industries in  the  area.   In  the
Seymour  aquifer, ground  water  movement  is  generally  to  the southeast.   The
aquifer  is susceptible to pollution  from  oil and gas  activities,  industrial
facilities,  and  agricultural practices.

Carrizo-WiIcox
The Carrizo Formation  and the  Wilcox Group are  two  separate  geologic units,
yet they are frequently considered  as one  aquifer.   Generally,  the  Carrizo
consists of well-sorted  quartz sand.   In some areas, it is poorly cemented and
contains thin beds  of  shale.   The Wilcox Group  consists mainly of interbedded
sand,  silt and  clay,  with minor  amounts of  lignite.   The sands are typically
gray and most  are  relatively  thin-bedded and silty;  individual  beds generally
                                     1-36

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                                                     Major Aquifers  in Texas
           MAJOR AQUIFERS
         qMHIH'H at MMV in larf* ana of tin Stow
              AHuvkn and Bollon OcpoUti

              EHwoMt-Trlnltr (Pmng)

              &JWOT* (Mam Rmll zซw)

              TMr*, Gow,
(Texas  Hater Commission)
           Figure 1-12.   Major Aquifers  in Texas
                                  1-37

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                                                       Minor Aquifers
                             rffilNlTY •
                       OHIGH..BLA1NS1
          7v>;-.:- r™i. ''"""^(yvNTA Rn'S'A-/ '  :
                                          •HICKORY \. ^ -,-.:.„;- .  /- - V^J"';•'••-•
                                 ELLENBURGER- SAN - SABA
                                            ;*••!ป T j,ซ -osc- j ป*O(H! r"  / (
(Texas Water Commission)
                   Figure 1-13.   Minor Aquifers in  Texas
                               1-38

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cannot be correlated.   The  principal  source of  recharge  to  the Carrizo-WiIcox
is rainfall on  the  outcrop  along  the  western  edge  of  the aquifer.   Additional
recharge  is  from the  numerous  streams which cross  the  outcrop.   Generally,
ground water  movement  is to  the  south-southeast.   Oil and gas  production  is
the major industry  situated on the  recharge zone.  The aquifer is  susceptible
to pollution on the outcrop.

Edwards-Trinity Group
The  Edwards-Trinity Group  is the  principal  source  of  water  in the  Edwards
Plateau  Region  of  Texas.   This  group  consists of Georgetown,  Edwards,  Com-
manche  Peak,  Trinity  Sand  and Glen  Rose Formations.   These formations  are
composed  of  medium to  thick-bedded limestone frequently  containing fractures
and  vugular  porosity.    Recharge is   from  precipitation,  runoff   and  stream
loss.  Generally, ground  water moves  from north to south or from northwest to
southeast.   Several  cases of  ground water contamination  have  been  documented
associated with septic tanks and animal feedyards.

Gulf Coast Aquifer
The  Gulf Coast aquifer  includes  a broad belt  of  sediments along  the  entire
coastal  plain  from  the shoreline  to approximately 100 miles  inland.   For the
most  part,  the  geologic  formations  included  in  the  Gulf  Coast aquifer  are
composed of sand, clay, silts, gravels, and  some tuff and volcanic  ash.   These
sediments dip  toward  the coast and ground water occurs  under both  unconfined
and artesian conditions.  Recharge  is  from  precipitation and  stream losses on
the outcrop.   The Texas Gulf Coast area is one of the most heavily  industrial-
ized zones in the  United  States,  and  the  potential for ground water pollution
is great.

Ogallala
The Ogallala occurs at the surface in most of  the Texas  Panhandle  area.   The
Ogallala  is  composed  of clay, silt, fine to  coarse  sand,  gravel and caliche.
Generally, individual  beds, lenses, sand,  or gravel cannot be traced over long
distances.   The formation  ranges in   thickness  from 0  to  500  feet.   Ground
water occurs under unconfined conditions and generally moves toward the south-
east at  a rate  of  50  to 150 feet  per  year.   Recharge is  from precipitation on
the outcrop  and underflow  from the Ogallala  in New  Mexico.   The  Ogallala is
                                     1-39

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probably  the  aquifer  with the greatest potential for ground water  pollution.
The  generally  unconsolidated  nature  of  the aquifer  and  the  occurrence  of
numerous  industrial complexes and oil fields have resulted  in many  documented
cases of ground water contamination.

Trinity Group
Frequently  called  the Trinity Sands,  this formation is the major aquifer for
North Central  Texas.    In  the north,  the  Trinity can usually be divided  into
two  zones,  the Paluxy  Sand  and  the Travis  Peak Formations.  In the  southern
area, these units are  separated by the  Glen Rose Formation.   Generally,  the
Paluxy consists of fine-grained quartz sand  and  the  Travis Peak  is composed of
fine-grained  sand  interfingered with  shale, clay, and limestone.  Recharge is
from  rainfall  and stream  losses on the  outcrop.  Water  generally  moves  east
and  southeast  and  occurs  under both confined and unconfined conditions.   Very
few  cases  of ground  water contamination  are  known  in this aquifer,  and  most
are  associated with septic tanks or other small  scale sources.

Edwards-Balcones Fault  Zone
The  Edwards-Balcones  Fault  Zone aquifer  is a limestone  aquifer, and  flow
exists primarily  in  solution channels.   Recharge to the  aquifer is from  pre-
cipitation  on  the outcrop and stream losses.   On the outcrop,  the  aquifer is
very susceptible to pollution because of  the thin soil mantle and rapid infil-
tration.   This aquifer has  been declared a sole source  aquifer  by  the  EPA.
Because  of  the  stringent  controls which exist  over  this  aquifer,   and  the
general lack of industry  in the area, little, if any, significant pollution is
expected,  although numerous  localized  effects  from septic  tanks  have  been
documented.

1.3.2  Ground Water Use
The  demand  for renewable  water  resources is  increasing  at a rapid pace.   In
many  aquifers  the annual   withdrawal  of  water  is greater than  the  annual  re-
charge.   The net  effect  is a depletion, or "mining," of underground storage
reservoirs.

When more  water is withdrawn from  an aquifer than  is recharged to  that  aqui-
fer, the lowered water  level results in lowered  well yield.   To  meet increased
                                     1-40

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water demands,  pumps must  be  set  deeper  and  larger  pump motors installed.   In
some cases, existing well development is inadequate, so new wells are added to
meet increased  demands.   Adding new wells and  lowering  the yield of existing
wells  causes  operating  costs to  increase  as' water  levels decline  further.
Besides reduced  well yields,  the dewatering of aquifers can reduce  the aqui-
fers' ability  to transmit water, can cause saline-water to move into heavily
pumped  fresh  water aquifers,  and  can  cause  the land surface to  subside.   As
the  ground water  resources  decline,  it  becomes more  and more  important  to
protect the resources  we have in order to ensure a sufficient  supply for  the
future.

1.4  WELLHEAD PROTECTION REQUIREMENTS
Recent  amendments  to  the  Safe  Drinking Water  Act  (SDWA), require  states  to
develop programs to protect wellhead areas of public water supply well(s) from
contaminants.   The programs  developed by the states  are required to identify
all  potential  anthropogenic  sources  of  contaminants  within  each  wellhead
protection  area.    One  major   task   required   by  the  amendments  is  the
determination of the size and shape and area to be protected.   These  areas  are
referred  to as  Wellhead Protection Areas  (WHPA's)  and  are  defined  as "the
surface and subsurface area surrounding  a water  well  or well  field,  supplying
a  public  water  system,  through  which contaminants are reasonably  likely  to
move toward and  reach  such water well or well fields."

The  June  1986  amendments to the SDWA  authorized  two  new programs for protec-
tion  of  ground water.    One of  these  is  the  Wellhead  Protection  Program
(WHPP).   The  intent of  Section  1428 of the  amendment is to  establish a state
program.   Unlike other programs authorized by the SDWA, the EPA is not author-
ized to establish  a federal  program if  states  elect  not to  develop  rules  and
regulations.  However, if states do not develop and submit programs to EPA  for
approval  within three  years  of  the enactment of the  amendments,  the EPA  may
withhold  grant  monies  to the state.   The  only mandated EPA action  is to  de-
velop and  issue  technical guidance to the states for development of WHPP's.

1.4.1  Wellhead  Protection Area Method Development
In order  to prepare a method for  actual determination of  the  area which will
be included  in  the WHPA, criteria  for establishing protection must  be devel-
                                     1-41

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oped.  The  criteria  developed  by  each  state  will  probably be a combination of
both technical and non-technical (political or administrative).  The technical
criteria are those activities that would reduce the contaminants to acceptable
levels.  The EPA has identified five types of technical criteria that could be
utilized.  They are:

          •  Distance from source to wellhead
             Radius of drawdown of pumping wells
          •  Time of potential contaminant travel
          •  Aquifer flow boundaries
          •  Assimilative capacity of the aquifer.

The purpose  of the WHPP is to  protect  the well fields from pollution.   Three
major targets, which are discussed below, are:

          •  Prevention  of   Direct  Introduction  of  Contaminants
             around the Well Casing.
          •  Prevention of Contamination by Bacteria and Viruses.
          •  Prevention  of  Contamination by  Naturally Occurring  or
             Synthetically Derived Organic Compounds.

1.4.2  Protection From Spills (Immediate Zone)
Many domestic,  industrial and  municipal  supply  wells have become contaminated
because of  poor well  construction  practices  or  by lack of sanitary control at
or near  to  the wellhead.  Prevention of  contamination of the  well as opposed
to the  aquifer has  generally been  dependent  upon construction  or operating
standards.   Table 1-6  lists  several  management methods  that  have been used,
and these are discussed in the following sections.

1.4.3  Well Construction Standards

1.4.3.1  Well Casings and Grouting
Casings, normally steel or PVC, are required in almost all water wells to pro-
vide a  base for  the  pumping  unit  and to prevent  the  geologic formation from
caving into the borehole.  However, when the wells are completed in hard rocks
such as  limestone,  granites, sandstones,  etc.,  casing may  not  be needed for
structural support of the borehole.  In many domestic wells, casing may extend
only 5 or  10 feet into the borehole and  there  may be  several  hundred feet of
                                     1-42

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                 TABLE 1-6

METHODS OF MANAGEMENT OF THE IMMEDIATE AREA
       Standards  for
            Well  Casing
            Grouting
            Housing
            Grading

       Establishment  of
            Buffer Zones
            Well  Plugging  Procedures
                    1-43

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open borehole before  the water table  is encountered.   This  type  of completion
can allow a  "short  circuit"  for  nearby  sources  of  pollution to enter the well
or aquifer.   For municipal  water  supply  wells, casings should extend to the
top of  the  water table  or  production zone and  should  be  cemented.  The in-
stallation of casing without grout can still  provide an avenue  of migration in
the casing-well bore annulus.  Figure  1-14  indicates  several  different comple-
tion methods  and  potential  problems.   Although most public  water supply sys-
tems will have adequate casing and cementing,  the following  discussions demon-
strate the potential problems that can exist  at wellheads and well completion.

1.4.3.2  Casing Installation
Steel casing installed in water wells is either thread  and collar or plain end
that is welded.  Plain end casing is cheaper  and can be run  in  a  smaller  hole;
because of this,  it  is  the  most  common  type  used in water well systems.   Many
early well drillers cut  holes in the  casings  to support the casing on a  cable
as it was  lowered into the hole.  After the  next  joint  of  pipe  was welded to
that  joint,  the  holes  were welded closed.   Frequently, these  holes if not
adequately welded  are weak  spots in the casing  and  can  allow  contaminants to
enter the  wells.    Downhole television pictures of  wells  at  Kelly  Air  Force
Base  in San  Antonio, Texas  and at Green  Pasture  Water Supply  System  near
Austin, Texas have documented the entrance of clay and  shales into water  wells
through casing patches.  When steel casings are utilized, corrosion can occur.
This  is  especially true where casings  penetrate alternating  layers  of  rocks
with different  lithologies, especially sand  and  clay  or limestone  and  clay.
It has been noted that frequently, at the contacts of these  two layers,  corro-
sion of  casing  will  occur and contaminants can  enter.   In  San Antonio,  down-
hole television  photographs demonstrated  the entrance of gasoline into  water
wells at  the contact between the  Buda limestone, and the  underlying Del Rio
clay.   The  casing was poorly cemented  in  this  zone, possibly  because of lost
circulation in the Buda  limestone or poor well cementing procedures.

1.4.3.3  PVC Casing
Within the last several  years, PVC  casing  has been approved for  use in  public
water supply system water wells.   The use of PVC has been especially prevalent
in areas where corrosion and iron  bacteria have been a problem.   However, the
use of PVC has created two potential problems for water supply  systems.   Where
                                     1-44

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static water  levels  are deep (200 - 300 feet), the heat of  cement  setting  up
has  resulted  in  the  weakening  and  collapse  of  PVC  pipe  above  the  water
table.   These circumstances  require  that the well be abandoned  or  the  casing
be milled  out slightly to accept the pumping equipment, thus  creating  a weak
spot which  could  potentially fail,  allowing contamination to  enter  the well-
bore.  An  additional  problem is the  fact that "bell  jointed" PVC well  casing,
which  is glued  together,  is frequently used.   Glued  joints  can  leach  MEK,
toluene  and hydrotetrafluor  into the  water.

Contamination  of  the  well  by pumping equipment is also possible.   Many water
supply  systems use  lineshaft  turbine  pumps.   Lineshaft  turbine  pumps  are
either water  lubricated or oil  lubricated.   Oil lubricated  pumps are  subject
to leaks and  it  is  not uncommon to find several feet of hydrocarbons floating
on the water  inside a water well.  This refined oil can result  in  low  levels
of dissolved  organics  being  detected  in the water from the  well.

1.4.4  Well Plugging Procedures
Although there are  generally procedures developed  for plugging and  abandoning
public water  supply wells,  most domestic  water wells  are  abandoned and  not
plugged.   Since  these  private  wells  are often completed  in  the same  aquifer
that supplies  public water supply systems,  they provide  an avenue of contami-
nation entrance  into  the  aquifer if  not properly  plugged.   In addition, these
domestic wells are  generally not cemented  or cased in  the same  manner  as are
public supply systems.   Accordingly,  in wellhead  protection zones,  procedures
should be developed to properly plug  and abandon domestic water supply wells.

1.4.5  Buffer  Zone
Most  public water  supply  systems have  established  buffer zones or  sanitary
easements around  their wells.   The minimum  requirement  for most water utility
companies  in  Texas  is  generally a 150-foot  radius  as  a  sanitary easement.  If
other  wellhead protection measures  are taken, such  as proper  site  grading,
concrete pads, etc., this  150-foot distance should be sufficient for immediate
area protection from spills  of materials that would contaminate a well.

1.4.6  Protection From Bacteria
The protection of drinking water from  pathogenic  organisms has been practiced
                                     1-46

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for many decades.   The  connection between polluted water  and  diseases  was  not
fully appreciated  until the late 1800's  and  in some areas of  underdeveloped
countries it  is  still not  recognized.   However,  even  after  the  recognition of
these facts, ground water was considered to  be free of pathogens and  the earth
was considered to be a  "natural filter."  This was  based  upon  early work using
sand  filtration  of  pathogenic organisms for  surface  water  supplies.    The
actual "elimination" of bacteria  and  viruses  from ground water  involves  more
than  filtration, although  this is an important factor in sand  aquifers.   The
concept of minimum distances from bacteriologic sources and  water supply wells
has been established  by many states.    Texas,  for  example,  requires  a  minimum
of  150 feet  sanitary  easement  around public water supply systems.   This  also
follows  the  general  recommendation  of the American  Water Works  Association
(AWWA).   Early  experiments  in California with the  injection of  sewage  in  a
sand  and gravel  aquifer suggested this distance was sufficient for the  removal
of bacteria.

In  addition  to  filtration,  elimination of  pathogens  in  ground water  is  the
result of  the  chemical conditions in  the  aquifer,  including  the  effect of
oxygen concentrations,  temperature and pH.

Various studies  on the  survival of viruses and bacteria have been conducted by
many  authors  (Keswick and Gerha, 1980; Yates,  et a!.,  1985;  etc.).  Based upon
these studies  and  case  histories, residence time  in  aquifers has been devel-
oped  in  European countries.   Residence time  is the  time it  takes for an in-
jected fluid to reach  the  point of production,  with the aquifer  providing
physiochemical treatment.   Residence times from  two  months  to  one  year have
been  recommended.    Regardless of minimum  residence  times,  these pathogenic
sources should also be  prohibited within a certain minimum distance,  such as
150 feet for the AWWA  or  100  meters  (325 feet)  recommended by  Matthess (EPA,
1987).   Artificial  recharge  with  treated  sewage effluent  is  practiced  in
several areas of the  world.   In one  major effort in El Paso,  Texas,  residence
times  in  excess of two years  are  predicted   and  the distance  from injector
wells to production wells  is over one mile.

Since  the  source  of  pathogens  can  be non-point  source such  as feces  from
animals,  polluted streams, etc.,  it will be  difficult to regulate or develop a
                                     1-47

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WHPA  based  upon area of  influence.   It is  probable  that most programs  will
rely upon a fixed radius concept for protection against bacteria and  viruses.

1.4.7   Protection from Contamination by Naturally Occurring or Synthetically
Derived Organic Compounds
With the rise of  industrial  development  since  the  early  1900's, inorganic and
organic chemicals  began to  appear  in  our  drinking water supplies.   Prior  to
this, contamination of  supplies was  generally  biologic  in nature.   Because  of
the diverse sources of  these chemicals,  they are currently  present  throughout
the earth;  that is,  traces of industrial pollution can be  found  in  all  areas
of  the  earth as  a result of transport  by wind,  rivers,  and  oceans.   Small
quantities  of  inorganic and  organic chemicals have  been detected  in  ground
water  systems  far removed  from  modern  industrial  societies.   For  instance,
ground  water  can be dated  in any area  of  the world  based upon  the trittium
contributed to the atmosphere by nuclear weapons testing.   Trash and  chemicals
dumped  into the ocean are carried significant distances by currents,  resulting
in  contaminants being  present  in areas that  do  not  generate these contami-
nants.  The protection of ground water  supplies from such  diffuse  sources  of
pollution  is  probably not possible, especially  since some of these problems
are global  in scope.

The intent  of the 1986 amendments was to establish  protection measures against
the more obvious source of contaminants, that is,  an identifiable  point source
or practice within the WHPA  developed for each  well or well  field.  All poten-
tial  sources  must be  identified  and control  strategies developed to prevent
release of  a contaminant from  a  source to the aquifer.   The WHPP's are the
responsibility of individual  states.  Protection from  contaminant  sources will
depend  upon dilution  and dispersion and  the consideration that the concentra-
tions that  ultimately reach  wells and are produced  will be of such low concen-
trations that  they  will not  be a hazard to human  health.   (This  assumes that
some concentration above absolute zero is acceptable for human health).

In the  development of the size of the WHPA, the states are required to look at
the mobility  and  persistence of the contaminants.  Since many of the organic
and  inorganic  contaminants   are  very  persistent,  wellhead protection  areas
could  be  exceedingly large.   In  cities  that  use  ground water as  a  source  of
                                     1-48

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drinking  water  and  have  large  cones of  ground  water  depression,  wellhead
protection areas will be quite large.

1.4.8  Wellhead  Protection Area Delineation Methods
Although the concept of  requiring a  buffer zone  or sanitary  easement around a
wellhead  has  been  in  existence for  some  time,  the  concept  of protecting  a
water source to  the point of where the water originates is  a  new concept.   The
EPA has  identified  several  methods  for developing a  WHPA.  These  methods  are
listed in Table  1-7.   The  methods range  from simple,  inexpensive and probably
politically  acceptable  to  the  complex,  expensive  and  politically  contro-
versial.  The main  focus of  the  EPA  programs will  be  the delineation of areas
that  impose  and  use  control  to  protect  water  supply wells.   Using  hydro-
geologic concepts versus fixed radii  will  result in larger areas being desig-
nated  and  will  affect  the price of  land;  thus, the  potential  for  political
pressure will increase.

1.4.8.1  Arbitrary or Calculated Fixed Radii
There  is  very little difference  in  the  arbitrary or  calculated  fixed radii.
Both  methods  result from drawing a  circle around the wellhead  or well field
with the well being at the center of the  circle.   The  calculated radii include
the concept  of  time  of travel  (TOT) or  volume  pumped  over  certain  times.
Figure  1-15  shows these two  methods.  The major problem with  this  method is
the assumption  that the aquifer is homogeneous  and that  the  piezometric  sur-
face  is  flat.    The  method  generally overestimates the downgradient area  and
underestimates the upgradient area.

1.4.8.2  Simplified Variable Shapes
The concept  of  variable shapes  includes  components   of  both  the calculated
radius and analytical methods.  This concept normally  results in an elliptical
shape, elongated in an  upgradient direction.   The standardized  form is  ori-
ented  around  the pumping well and  aligned with  the flow  direction.   The  up-
gradient extent  is  calculated using  a TOT criteria;   Figure  1-16  illustrates
this concept.
                                     1-49

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                 TABLE  1-7

WELLHEAD PROTECTION AREA DELINEATION METHODS
       Arbitrary and Calculated Fixed Radii
       Simplified Variable Shapes
       Analytical Methods
       Hydrogeologic Mapping
       Numerical Flow/Transport Models
                    1-50

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             DIRECTION OF GROUND WATER FLOW


              I
SOURCE: EPA.1987
                     Figure 1-16.  Variable Shapes  for WHPA Delineations
                                       1-52

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1.4.8.3  Analytical Methods
In order to  calculate  the  WHPA  using  analytical  techniques,  values  of various
hydrogeologic parameters are required as input into the formulas.   Using these
values  and  standard ground water  flow  equations,  the WHPA  can be  determined
based upon  time of travel or flow boundaries.   An example  of this  method  is
shown in Figure  1-17.

1.4.8.4  Hydrogeologic Mapping
Standard geologic  mapping  techniques can  be  utilized to determine  the WHPA.
The  flow  boundaries or  aquifer boundaries frequently coincide with geologic
contact.  Aerial photographs, satellite images and  both surface and  subsurface
geophysical techniques are useful.  Figure 1-18 indicates two examples of WHPA
determination using geologic methods.

1.4.8.5  Numerical  Flow/Transport Models
Where aquifer  boundaries are complex or  where numerous recharge -  discharge
points exist, the  determination of WHPA becomes  complex.   These  complex prob-
lems  are  better  suited  for  computer solution.    Numerous  ground water  flow
models  exist  that can be  run on  either a  prime or a micro  computer.   Input
data requirements  for most flow/transport models  are extensive and include but
are  not limited to permeability,  porosity,  thickness,  recharge rates,  and
recharge location.  Where  these data  are  available,  numerical flow  models are
probably one of the better methods of  determining  WHPAs.   However,  if little
data exist,  it  is probably more desirable  to  use  an analytical  or  hydrologic
solution.

1.4.8.6  Conclusion
A review  of the  methods  available for  determining the WHPA was  conducted  by
EPA  for  several hypothetical areas.  Figure 1-19  is an example  of  the areas
determined  using  three  different  methods  and  assuming  a  25-year time  of
travel.  This  same general shape  was established  in most  of the  comparisons;
that  is,  the  analytical  and  numerical model  give  similar shapes  and  both
identify those   areas  that should  receive  protection from  pollutants.   The
calculated  fixed radii  give  somewhat similar answers only  in those instances
of flat water  tables  and  low times of  travel.   If  states  adopt  the more com-
plex method of  analytical  and numerical modeling,  most  state agencies will  be
                                     1-53

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                                                                GROUNDWATER
                                                                    DIVIDE
                                                                        A'
LAND SURFACE
                                                                   PREPUMPING
                                                                   WATER LEVEL
                                                                   BEDROCK
                            A) VERTICAL PROFILE
                               (B) PLAN VIEW
            LEGEND:
              V Water table
                ป Ground-water Flow Direction
               • Pumping Well
              ZOI Zone of Influence
              ZOC Zone of Contribution
                     Figure 1-17. Analytical Method for WHPA  Determination
                                      1-54

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                                                        •'   '   -
         EXPLANATION
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SOURCE: EPA, 1987
               Figure  1-19.   WHPA Comparison for Three Methods
                                  1-56

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required  to  increase their  staffs.   The  new staff members  will  have to  be
experienced ground  water hydro legists,  who at  the  present time command  sig-
nificant salaries.
                                     1-57

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     SECTION 2.0
GROUKD WATER CHEMISTRY

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                          2.0  GROUND WATER CHEMISTRY

The most  important  sources  of dissolved substances  in ground water  are  the
minerals  in  the soil, in near-surface sediments, and  in  the  sediments of  the
aquifer which  contain the  ground water.   The  chemical  quality of the recharge
also  influences the  quality of the  water in  the aquifers.   As  rain  falls
through the  atmosphere, natural gases such as  carbon dioxide,  sulphur dioxide,
nitrogen  and oxygen,  and man-made  airborne pollutants  are  dissolved  into  the
rain.    As a result of the  solution  of  the  atmospheric gases, the  pH  of most
precipitation  is  acidic  (less  than  7)   and rainwater   is  slightly  corrosive.
Upon  reaching  the  surface of the earth,  the  water  may increase  its corrosive
character by picking up  organic acids from soils,  when  the  water percolates
through the  subsurface toward  the water  table,  the  water  dissolves the miner-
als in  the  sediments  and  rocks.  The amount  and character of the mineral ions
entering  the  ground  water depend  on:    1)  the chemical  composition of  the
water;  2) the  mineralogical  and  physical structure  of the  rocks  in  contact
with  the  water; 3)  the temperature and  pressure at  which  the solution occurs;
and 4)  the  amount  of time  the  water stays  in contact with  rocks  and  sedi-
ments.   Nearly every element may be present  in ground water, and the mineral
content can  vary  from aquifer to aquifer.  Table  2-1  demonstrates the varia-
tions in  common dissolved  inorganic  compounds that  can be expected in natural
water.   Table 2-2  lists  the  Texas and  EPA Standards  for  Drinking  Water.   In
many  areas   in  the  state,  the  natural  ground  water  cannot  meet  these  stan-
dards.

2.1   CONSTITUENTS IN  GROUND WATER
Many  organic  and   inorganic  compounds  in ground  water,   that might  also  be
present  in  industrial  wastes, occur  naturally.   Thus,   it   is  important  to
establish, as  best  possible, whether a specific constituent can occur natural-
ly  and  what the natural  concentration  might  be or actually  is.   Frequently,
the occurrence  of metals or organic compounds in ground water and/or soils are
viewed  only  as contamination.  The following discussion  provides an overview
of  the  source  and  significance of  chemical  constituents  frequently  found  in
ground water.
                                      2-1

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                                TABLE  2-2

               Texas and EPA Standards for Drinking Water
                                                      EPA-Interim Pri-
                                                      mary and Proposed
                              Texas State Health      Secondary Drink-
                               Dept. Primary and         ing Water
                              Secondary Standards        Standards	

Ca                                    *                       *
Mg                                    *                       *
Na + K                                *                       *
HC03                                  *                       *
S04                                  300                     250
Cl                                   300                     250
Fe                                  0.3                     0.3
F                                 1.4-1.8                 1.4-2.4
N03                                   45                      45
pH                                    >7                  6.5-8.5
TDS                                 1000                     500
Mn                                  0.05                    0.05
As                                  0.05                    0.05
Cd                                  0.010                   0.010
Cr                                  0.05                    0.05
Pb                                  0.05                    0.05
Cu                                  1.0                     1.0
Zn                                  5.0                     5.0
Phenols                           .01-.10                 .01-.10
Hg                                  0.002                     *
Ba                                  1.0                     1.0
Sn                                  0.01                    0.01
Ag                                  *.05                     .05
Chlorinated Hydrocarbons:
  Endrine                           0.0002                  0.0002
  Lindane                           0.004                   0.004
  Methoxychlor                      0.1                     0.1
  Toxaphene                         0.005                   0.005
Chlorophenoxys:
  2, 4-D                            0.1                     0.1
  2, 4, 5-TP Silvex                 0.01                    0.01
All units in mg/L, except pH
*No standards established.

                                 2-3

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2.1.1  Inorganic Constituents
Silica
Silica is usually  reported  in water analyses  as  SiC^,  although  it  is believed
to occur  as monomeric silica acid, H4Si04,  at the normal temperature and  pH
ranges of natural water.  The natural  accumulation of  residual quartz and  clay
minerals attests to  the  relatively slow rate of  solution  of certain silicate
minerals.   The  moderately  rapid  disintegration  of  other silicate  minerals,
notably in volcanic and igneous rocks, releases sufficient silica in  a soluble
form to  account  for  the concentrations found in  natural  waters.   The concen-
tration  commonly ranges from 5  to 40 mg/L  silica in natural  ground  waters.
Dissolved silica forms a hard scale in  pipes  and boilers  and on  the  blades  of
turbines.

Calcium and Magnesium
Subsurface  waters  in contact with sedimentary  rocks  of marine  origin derive
most of  their  calcium and  magnesium from the  solution  of calcite,  aragonite,
dolomite, anhydrite and gypsum.   Large  quantities of  both ions  can be present
in some  brines.    The most  commonly  noted  effect of  these  ions in  water  is
their  tendency to react  with soap to  form a  precipitate called soap  curd.
This soap neutralizing power is called water hardness.

Sodium
All natural  waters contain measurable  amounts  of sodium.  In ground waters,
the primary  source is the  weathering  of  both igneous  and sedimentary rocks.
High concentrations  combine with chloride to give a  salty taste to  water and
may limit the  use  of water for  irrigation.   However,  moderate  concentrations
have little effect on water quality.

Potassium
The weathering of  minerals  in igneous and metamorphic  rocks produces most  of
the potassium  in ground  waters.    In areas with  extensive evaporite  deposits,
waters may  dissolve  large  amounts of  potassium.   Potassium commonly has  one-
tenth the concentration in  water as sodium,  because potassium  is incorporated
into clays and plants more readily.
                                     2-4

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Iron
Abundant  sources  of  iron exist in the earth's crust.  The weathering  of  many
minerals  releases large  quantities  of  iron  which are  usually converted  to
insoluble  and  stable  iron oxides.    Concentrations  are, therefore,  low  in
natural waters.   Upon exposure to air,  iron oxidizes to  a reddish  brown  pre-
cipitate, making  a concentration greater than 0.3  mg/L objectionable  for  food
processing,  beverages,   ice  manufacturing,  brewing,  and textile  manufactur-
ing.  Concentrations above 0.3 mg/L will  result  in  fixture staining.

Bicarbonate
Most bicarbonate  ions in ground water result  from the carbon  dixoide  in the
atmosphere,  carbon  dixoide in the soil,  and  the  solution of  carbonate  rocks
such as  limestones  and  dolomite.   Ground water  usually  contains more  than 10
mg/L but  less than 800 mg/L bicarbonate.  Only  rarely does  ground  water  have
pH  less  than  4.5,  causing bicarbonate to convert  to carbonic acid,  or  more
than 8.2, where  bicarbonate  will  dissociate to carbonate.   Alkalinity  is  a
measurement  of  bicarbonate.  In combination with calcium  and  magnesium, bicar-
bonate causes hardness.   Under high  temperature conditions  such as  in  steam
boilers and  hot water heaters, a calcium-magnesium  carbonate  scale  will form.

Sulfate
Most sulfate found  in ground water results from the  dissolution of rocks and
soils  containing  gypsum,  iron  sulfides,  and other  sulfur  compounds.   Atmo-
spheric sulfur dixoide,  from natural  and man-made sources,  causes  sulfate to
be one of  the major  dissolved  constituents of  rain and  snow.  Sulfate is also
commonly present  in  industrial wastewaters.  Natural  concentrations range from
0.2 mg/L  in  rain to 100,000  mg/L  in magnesium sulfate  brines.  High sulfate
waters have  a bitter taste and form a scale in steam boilers.  The  federal and
state  limits  for  sulfate in  drinking  water are  250 mg/L  and  300 mg/L, respec-
tively.   Consumption of  water with high sulfate and  magnesium concentrations
may have  laxative effects.

Chloride
Most chloride in  ground  water conies from:  1) the solution of evaporite miner-
als, 2) concentration of evaporation of chloride in rain  and  snow,  and 3)
                                      2-5

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ancient seawater entrapped in sediments.  Chloride  is  also  present  in  sewage,
oil  field brines,  seawater,  and  industrial  waste  streams.    Once chloride
enters ground water,  it  is difficult to remove  by  natural  processes.   Concen-
trations range from 0.1 mg/L in snow to 150,000  mg/L in brines.   Large  amounts
combined with sodium  give water a salty taste and  can  increase  the  corrosive-
ness of  water.   The  federal and state  limits  in drinking water are 250  mg/L
and 300 mg/L, respectively.

Nitrate
Nitrate  comes from  decaying  plant  and animal  matter,  nitrogen fertilizer,
return flow  of  irrigation water,  barnyard  and  feedlot leachate, sewage,  and
natural  soil  nitrogen.   Nitrate  is highly soluble, and  can  be removed  from
ground water  through  the activity of  plants  and bacteria.  Waters with  high
concentrations of nitrate can cause  a fatal  disease in  infants  called methemo-
globinemia.   Such  waters  may be  linked  with  gastric cancer  as  well.   The
federal and  state  limits in drinking water are  45 mg/L as  nitrate  or  10  mg/L
as nitrogen.

Fluoride
Fluoride  is  dissolved  in small  quantities  from most  rocks and soils.   Many
municipal  water  supplies  add  it  to their  distribution   systems.   When  the
concentration approaches  the  optimum value,  from 0.7  to  1.2  mg/L,  fluoride
reduces the incidence of tooth decay in children.  Excessive amounts in drink-
ing  water can mottle  teeth, depending  on  the  age  of  the child, the  concen-
tration of fluoride,  the amount of  water drunk,  and the susceptibility of the
individual.  Both state and  federal  limits  exist for fluoride  concentration in
drinking water.

Metals
Samples  of  ground water  and  frequently "soil  samples"  from the  unsaturated
zone are  collected  and  analyzed for  metals.   Soil,  in  most places,  is  a natu-
ral residuum  developed  by prolonged  weathering  of  the  bedrock.   In  contamina-
tion studies, samples of soil  (upper 1  to  3 feet) are normally not  taken since
waste migration from  lagoons,  etc.  generally occurs at  a deeper depth.   There-
fore, samples collected for chemical analysis during waste site investigations
are  normally  geologic materials,  not soils.   Since the geologic material  is
                                     2-6

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not as uniform  as  soils,  one  would  expect  a wide  potential  range of naturally
occurring compounds within any set of samples.

Data presented  in  Table 2-3 demonstrates the wide range  of concentrations  of
metals in  naturally occurring  substances  including  soil and  bedrock.   This
list was  compiled  from 11  sources.   Given sufficient time, the  ranges  shown
here could certainly be expanded.   Accordingly, one  must  be careful in making
assumptions   about   the  source  of  metals  when   conducting   contamination
studies.   A  discussion  on the possible  natural  and man-made sources of metals
is contained  in Table 2-4.

2.1.2  Organic Constituents
The  occurrence  of  elevated  concentrations of  certain  organic  compounds  and
frequently,  ratios or concentrations of common inorganic compounds is, in most
situations,  an  indication  of contamination related  to  disposal  activities.
Although it  might  be presumed that  all  detected organic compounds are derived
from the wastes at a site, this is not the case, as numerous organic compounds
occur naturally or occur  as nonpoint sources of pollution.

Lignite  is  very common  in many  areas  of east and  south central  Texas.   In
these areas,  low concentrations of  naturally occurring  organics  may be diffi-
cult to  distinguish  from  contamination by man.  Table  2-5  presents a list  of
organics frequently found  in coal.

Coal is  a  heterogeneous solid originating from plant material,  but also con-
taining  inorganic  sedimentary material, i.e.,   sand, silt,  clay,  that accumu-
lated with the plant material.  The principal elemental  composition of coal  is
carbon, hydrogen,  nitrogen, and sulphur, with  carbon predominating.  Coal  has
a structure  similar  to cross  linked polymers.  The  main organic functionali-
ties are carbonyl, hydroxyl, aromatic, and heterocylic.   Alkyl  side chains are
common,  especially  one  and  two  member  aromatic  rings,  e.g.,  benzene  and
naphthalene.

When coal is  oxidized, polynuclear aromatic hydrocarbons  (PNAs) are generated,
along with the  phenols  and cresols.   Similar compounds  are  found in liquified
coal.  PNAs  are also common  constituents in coal tars  and  cresol  tars.   Com-
                                      2-7

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                                                TABLE  2-3
                 TRACE METAL CONCENTRATIONS: RANGE IN COAL, ASH, BEDROCK, SOIL, AND PLANTS"
Elements
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Selenium
Silver
Thalium
Tin
Vanadium
Zinc
RANGE IN COAL
REF 1,2,4,5,9
0.04
0.10
20 -
0.1 -
0.01
0.25
0.05
0.13
1,800 -
0.37
100 -
0.75 -
0.01
0.32
0.02
0.02
<0.2
0.04
4 -
1.0 -
- 43
- 420
3,000
1,000
- 170
- 220
- 930
- 300
100,000
- 590
20,000
3,500
- 33
- 580
- 150
- 2
- 8
- 51
300
5,350
RANGE IN COAL ASH
REF 1,3,5,7
5.6
2.8
96 -
1
1 -
10 -
10 -
10 -
78,000
20 -
11,900
10 -
0.1
3 -
0.77
1
0 -
10 -
6 -
50 -
- 100
- 200
13,900
- 60
100
1,000
10,000
3,020
- 480,000
1,500
- 79,300
10,000
- 18
10,000
- 40
- 60
17.1
4,250
5,000
1,200
RANGE IN BEDROCK*
REF 6,8,10
0.1 - 1
<1 - 39
<1 - 7,500
<1 - 12
<1 - 12
<1 - 700
0.01 - 71
<1 - 400
<500 - > 100,000
<3 - 7,000
<60 - 98,000
0.5 - 10,000
0.05 - 1500
<2 - 420
<0.1 - 12
<0.2 - 10
0.3 - 3
<10 - 20
<2 - >1,100
6 - 2,300
RANGE IN SOIL
REF 2,6,8,10,11
<150 - 500
<0.1 - 183
15 - 5,000
<1 - 7
0.01 - 11
1 - 4,000
.05 - 300
<1 - 5,000
100 - 123,000
2 - 1,200
50 - 100,000
<2 - >20,000
<10 - 4600
<5 - 5,000
0.03 - 10
<0.5 - 30
0.02 - 5
1-100
<5 - 500
<5 - 2,000
RANGE IN PLANTS
REF 2,8,10,11
-
0.2 - 30
5 - 50,000
<2 - 7
<0.2 - 60
0.01 - 150
0.05 - 10,000
4 - 7,000
100 - 20,000
0.1 - 3000
4,000 - 240,000
15 - 50,000
<0.1 - 50
1 - 1,300
<0.01 - 4.8
<0.4 - 20
<2
<15 - 30
0.1 - 700
15 - 10,000
* Sandstone, shale, mudstone, siltstone, limestone
REF - References
- No references on concentrations found
" all numbers are expressed in ppm
1) Bush and Colton, 1983
2) Lisk,  1972
3) Torrey,  1978
4) Swaine,  1977
5) Valkovic, 1968
6) Aubert and  Pinta,  1977
7) Sauchelli, 1969
8) Conner and  Shacklette, 1975
9)  Ruch, Gluskoter,  Shimp,  1974
10) Smith and Carson, 1977
11) Brown,  1980
NOTE: This table was compiled by combining information from various documents and references. Many authors stated a range in or
       average value of concentrations, without stating the number of samples tested or the locality from which the samples were taken.
       For this reason, there is no feasible manner in which to ascertain the number of samples from which the table was compiled. Also,
       there  is no direct relation between the values in the various columns.
                                                     2-8

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METAL

Antimony
Arsenic
Barium
Beryl!ium
Cadmium
             TABLE 2-4

        OCCURRENCE OF METALS



                        USE

Industrial  Occurrence:    medicinal   agents,   on  safety
matches, in vulcanizing rubber, as a  pigmenting  agent  in
glass  and  porcelain, the  bronzing  of steel,  and as  a
caustic in medicine
                     Natural  Occurrence:
                     particles
                       as  the  mineral  stibnite,  fly-ash
Industrial Occurrence:   insecticides,  herbicides,  pesti-
cides, pigment production,  manufacture of glass,  manufac-
ture  of  Pharmaceuticals,  textile   printing,   tanning,
taxidermy,  and  in  lubricating  oils   to  control  sludge
formation
                     Natural  Occurrence:
                     arsenic
                      yellow arsenic  (III)  sulfide,  gray
Industrial Occurrence:   insulator  for  electrical  appara-
tus, alloy constituent  in  automobile  spark  plugs,  addi-
tive to increase the weight of drilling  fluids;  in  medi-
cine, it  is given to  patients when X-ray photographs are
to  be  taken  of the  gastrointestinal   tract because  it
absorbs X-rays so well

Natural Occurrence:   as  the minerals barite and  witherite

Industrial Occurrence:  primary use  is as  an additive in
structural metal  alloys,  also   in electrical  contacts,
springs,   nonsparking  tools,  and X-ray  tubes,  electrical
applications   in televisions,  computers,  and  beryllium
alloys in personal  body  armor
                     Natural Occurrence:
                     cles
                     in the mineral  beryl, fly-ash parti-
Industrial Occurrence:   electrolytically  deposited coat-
ing on  metals,  solder,  photographic  chemicals,  manufac-
ture of fireworks,  rubber,  fluorescent  paints,  glass and
porcelain, smelting  and plating  operations, and  litho-
graphy.

Natural Occurrence:   found  associated with lead, copper,
and zinc  ores;  leaves of tobacco  plants;  fly-ash parti-
cles
                                      2-9

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                                  TABLE 2-4

                       OCCURRENCE OF METALS (Continued)
METAL

Chromium
Cobalt
Copper
Iron
Lead
Magnesium
                        USE

Industrial  Occurrence:   the  most common use  of  chromium
is  in  the  production of metallic  products;  pigmenting
agents in paints,  photographic processes,  tanning,  corro-
sion inhibitors,  and fungicides
                     Natural  Occurrence:
                     particles
                       metallic  ore,  chromite;  fly-ash
Industrial  Occurrence:   alloy  in metals in  the  electri-
cal,  automobile,  aircraft,  and  tool  steel  industries;
pigments in  enamels,  glazes,  paints  and  in the  glass,
pottery, and electroplating industries

Natural Occurrence:   as  arsenides, sulfides,  and  oxidized
mineral forms;  coal  fly-ash particles

Industrial  Occurrence:   electrical circuitry,  castings,
rods, tubing, water  and  gas piping, cooking utensils,  and
coninage;  insecticides,   algicides,  plant   fungicides,
pigments and  in  fertilizers as  a copper  supplement  for
pastures

Natural  Occurrence:     copper  ores  such  as  malachite,
cuprite,  chalcopyrite,   emitted   as  fumes   in  the  coal
combustion process

Industrial   Occurrence:    wrought  iron,  cast  iron,  and
steel; galvanized sheeting and  electromagnets

Natural Occurrence:    as the  minerals  hematite,  hoethite,
magnetite,   siderite,   and  limonite;   fly-ash  particles
derived from coal

Industrial  Occurrence:  lead plates in sotrage batteries,
electrical  cables,  as  lining  material  in pipes,  tanks,
and X-ray apparatus;  glass manufacture,  drier in oils and
varnishes,  pigmenting  agents in paints,  and as a gasoline
additive

Natural Occurrence:    galena, the ore of lead;  leaves of
tobacco plants; fumes  in the combustion  of  coal

Industrial  Occurrence:   castings for airplane  parts and
varied  metallurgical  applications; optical  instruments,
photographic flashlight  powders, incendiary bombs,  as  a
medicinal agent in the product  known as  "Epsom Salt"
                                     2-10

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                                   TABLE  2-4

                       OCCURRENCE OF METALS (Continued)
METAL
Manganese
                   USE
Mercury
Nickel
Selenium
Silver
                     Natural Occurrence:
                     site
                     in the minerals dolomite  and  magne-
Industrial  Occurrence:   iron  and  steel  industry as  an
agent used to reduce oxygen and sulfur  content  of molten
steel; manufacture  of dry cell  batteries, paints,  var-
nishes,  inks, dyes, matches  and fireworks, as  a  fertil-
izer, disinfectant,  bleaching agent, and  as a  coloring
agent in the  glass and ceramics industry
                     Natural
                     ashes
         Occurrence:    the  mineral  pyrolusite,  in  coal
Industrial Occurrence:   thermometers and other scientific
apparatus, vacuum  pumps,  barometers, switches,  electric
rectifiers;  common  antiseptics,   pigments,   electrodes,
fungicides
                     Natural Occurrence:
                     cles
                     the mineral  cinnabar,  fly-ash parti-
Industrial Occurrence:    metallurigcal  alloys,  coinage,
smelting,   electroplating,    nickle-cadmium   batteries,
nickel  soaps  in  crankcase  oils,  colored  ceramics  and
glass

Natural Occurrence:   as the  minerals  garniete, millerite,
niceo lite, pent 1 andite, and  pyrrhotite;  leaves of tobacco
plants

Industrial  Occurrence:    photoelectric  devices,  as  a
coloring  agent   in   glasses   and  enamels,  additives  to
vulcanized rubber, insecticides; and  in  medicines used to
treat dandruff,  acne,  exzema,  seborrheic  dermatitis, and
other maladies;  printing paper and  xerography

Natural Occurrence:   as an amorphous  mass  called vitreous
selenium, lustrous crystals  called  metallic selenium

Industrial  Occurrence:    jewelry,   tableware,  coinage,
various  medicinal  applications, photographic  processes,
smelting and plating operations

Natural  Occurrence:    as  the ores cerargyrite,  pyrargy-
rite, sylvanite,  and argentite; fly-ash  particles associ-
ated with coal combustion
                                     2-11

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                                  TABLE 2-4

                       OCCURRENCE OF METALS (Continued)
METAL
Thai "Hum
Tin
Vanadium
Zinc
                   USE

Industrial  Occurrence:    rodenticides,  fungicides,  in-
secticides,  bromoiodide crystals for  lenses,  plates,  and
prisms in infrared optical  instruments

Natural Occurrence:   occurs  in  combination  with  pyrites,
zinc blende, and hematite;  leaves  of tobacco plants; coal
fly-ash particles

Industrial  Occurrence:   various utensils,  cups,  plates;
metallic alloys,  protective  metals  coatings,  heat stabi-
lizers  in chemical  processes, catalysts, wood  preserva-
tives, and in textiles as biocides
                     Natural  Occurrence:
                     tinstone
                        as  the  minerals  cassiterite  or
Industrial Occurrence:   metallic alloys, manufacture  of
sulfuric  acid,  photographic  developers,   as   reducing
agents, and as drying agents in various paints

Natural Occurrence:   as  the minerals  roscoelite,  vanadi-
nite, and carnotite;  coal fly-ash particles

Industrial Occurrence:   protective  coating  for  iron and
steel; paint  pigment,  filler in  rubber tires, antiseptic
ointment, wood preservative, and soldering fluid
                     Natural  Occurrence:
                     and smithsonite
                      the  principle  ores  are  sphalerite
                                     2-12

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                                TABLE  2-5
EPA HAZARDOUS  LIST  COMPOUNDS FOUND IN COAL1

VOLATILES                    EXTRACTABLES                      TYPE

Benzene                  Naphthalene                            pna3
Toluene                  2-Methylnaphtalene                     pna
Ethyl benzene             Fluorene                               pna
Xylenes                  Phenanthrene                           pna
                         Anthracene                             pna
                         Fluoranthene                           pna
                         Pyrene                                 pna
                         Chrysene                               pna
HAZARDOUS  SUBSTANCE  LIST ORGANICS  RELEASED  INTO  ENVIRONMENT FROM COAL COMBUS-
TION/

VOLATILES                 EXTRACTABLES                          TYPE

Benzene                   Benzole Acid
Toluene                   Aniline
Xylene                    Benzidene
Carbon Disulfide          Phenol
                          Cresol
                          Benzo (A) Pyrene                       pna
                          Dibenz (ah) Anthracene                 pna
                          Chrysene                               pna
                          Ideno (123cd) Pyrene                   pna
                          Pyrene                                 pna
                          Acenaphthene                           pna
                          Acepahthylene                          pna
                          Fluorene                               pna
                          Anthracene                             pna
JvALKOVIC, VLADO, TRACE ELEMENTS IN COAL VOL. I
^TORREY, S. (ED), TRACE CONTAMINANTS FROM COAL
ฐpna =  polynuclear aromatic
                                       2-L'

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pounds  found  include  several  volatiles as  well  as  extractables,  which  are
mostly PNAs.

Potential concentrations of these organic compounds  in coal  are not  known,  but
presumed  to be low.   Table 2-5 also contains  a  list of hazardous  substance
organics released  into  the  environment  from  the combustion  of  coal.   In areas
where  lignite  or coal  power plants  exist,  these  compounds  may also  occur in
the air.

2.2  SIGNIFICANCE OF LOU CONCENTRATIONS OF ORGANIC AND INORGANIC COMPOUNDS
The tendency  in conducting investigations is  to  review chemical analysis of
soils,  ground  water,  and  surface wastewater  in  order  to  determine what is
present  and what the relationship is  to a waste site.   Frequently,  anything
found, no matter  how  far away  from the  site, is attributed  to  the site.  This
is often in error  and  fails to realize the  multitude of compounds  which  are
now in the  environment as  a result  of  many  industrialized  activities.   These
compounds are frequently referred to  as non-point  source contaminants.

Examples of these non-point source contaminants can be found in the  volumes of
data collected as part  of the National  Urban  Runoff Program  (NURP).   Table  2-6
contains  data   from the Austin program and demonstrates  the  wide  range of
pollutants  that  can be found  in urban  settings that  cannot be related  to  any
particular  point source of pollution.

While  inorganic and organic compounds can  naturally occur in soil and aquifer
matrices, very  little data have been presented in the  literature which docu-
ment that naturally occurring metals  and organic substances  would be dissolved
in ground water.  However,  our theory of the  origin of dissolved substances in
ground water would  suggest that they could.    A 1983  Canadian  study also sug-
gests  that  it  is  possible.  Table  2-7  lists  the concentration  range of chemi-
cals found  in  peat in  three peat bogs  in Canada.  Table  2-8 is the result of
analysis  of waters  from these  bogs,  indicating that  both metals  and organics
were found.  Although these data are  from Canada,  many areas in the  Gulf Coast
are "swampy" and buried plant and wood detrital matter are very common.
                                     2-14

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                 TABLE 2-6
    NATIONAL  URBAN RUNOFF PROGRAM (NURP)
    PRIORITY POLLUTANT SAMPLING RESULTS

(AIL SAMPLE RESULTS ARE IN  ug/l UNLESS NOTED)
Range of Pollutant Concentrations
in NURP* Storm Water
Samples That Were Above
Pollutant Detection Limit (U9/D
Metals and Inorganics
Antimony 2
Arsenic 3.3-37
Bery 1 1 ium
Cadmi um
Chromium 2-61
Copper 2-110
Cyanide 2-33
Lead 37.6-460
Mercury
Nickel
Selenium 0-225
Si Iver
Thai 1 ium
Zinc 10-546
Pesticides
Acrolein
Aldrin
Chlordane 0.01
DDO
DOE 0.35
DOT 0.008-0.1
Dieldrin 0.2
EndosuHan and Endosulfan Sulfate
Polycyclic Aromatic Hydrocarbons
Acenaphthene
Acenaphthylene
F luorene
Naphthalene 1-13
Anthracene '-7
Fluoranthane 0.3-15
Phenanthrene 0.3-7
Benzolalanthracene 1-3
Benzo(b) f 1 uoranthene 2
Benzo(k) f 1 uoranthene 4
Chrysene 0.6-6
Pyrene 0.3-13
Benzo ( gh i ) pery 1 ene
Benzo(a)pyrene 1-2
D i benzol a, h) anthracene
1 denot 1 ,2.3-cd)pyrene
Halogenated Ethers
Bislchloromethyl lether
Bis(2-chloroethyl lether
Bis(2-ch loroisopropy 1 )ether
2-chloroethy I vinyl ether
4-chloropheny 1 phenytether
4-bromopheny 1 pheny)etner
Bis (2-chloroethoxy)methane
Phthaiate Esters
Dimethyl Phthalale
Number ot All NURP* Samples
That Reported Values
Above Detection Limit/
Number of Samples
Analyzed for Compound

1/28
16/28


18/28
26/28
7/27
26/28


6/28


26/28

0/42
0/42
1/42
0/42
1/42
2/42
1/42
0/42
0/42

0/41
0/41
0/41
4/41
4/41
5/41
7/41
2/41
1/41
1/41
4/41
5/41
0/41
2/41
0/41
0/41

0/41
0/41
0/41
0/41
0/41
0/41
0/41

0/41
                  2-15

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       TABLE 2-6 (Continued)
NATIONAL  URBAN RUNOFF PROGRAM  (NURP)
PRIORITY POLLUTANT  SAMPLING RESULTS
Range of Pollutant Concentrations
in NURP" Storm Water
Samples That Were Above
Pollutant Detection Limit (ug/l)
Diethly Phthaiate 1-5
Di-n-butyl Phthaiate 3-11
Di-n-octyl Phthaiate 1-3
Bis(2-ethylhexy)Phthalate 1-42
N-butyl Benzyl Phthaiate
Pol ychlori nated Bipnenyls and
Related Compounds
PCB-1016
Aroclor 1221
Aroclor 1232
Aroclor 1242
Aroclor 1248
Arcolor 1254
Arcolor 1260 0.03
2-ch 1 oroanaph tha 1 ene
Nitrosamines and Other N Compounds
Dimethyl Ni trosami neป
Dimethyl Nitrosamine
Di-n-propyl Nitrosamine
Benzidl ne
3 ,3-d i ch lorobenz i di ne
1 ,2-dipheny I hydrazine
Aery Ion 1 tr i le
Halogenated Aliphatic Hydrocarbons
Chloromethane (Methyl Chloride)
Dich loromethane
(Methyiene Chloride) 5-1,645
Trochloromethane (Chloro(orm) 0.2-8
Tetrachorome thane
(Carbon Trachloride) 1-4
Chloroethane (Ethyl Chloride)
1 ,1-dichloroethane (Ehty 1 i dine Chlor ide) 1-5
1 ,2-dtchloroethane (Ethylene Chloride) 4
1 , 1 , 1 -tr i ch 1 oroethane
(Methyl Chloroform) t-23
1 ,1 ,2-trichloroethane 1-3
1 ,1 ,2,2-tetracnloroethane 1/3
Hexach 1 oroethane
Chloroethene (Vinyl Chloride)
1 , 1 -d i ch loroethene
(Vinyl idine Chloride) 1-4
1 ,2-trans-dichloroethene '-3
Tr ichloroethene '-3
Tetrach loroethene 4-43
1 ,2-dich loropropane 3
1 ,3-dichlorpropane 1-2
Hexach lorobut ad i ene
Hexach lorocycl open tad i ene
Bromomethane (Methyl Bromide)
Bromodichlorometnane 2
Olbromochloromซtnenซ 2
Tr i bomomethane (Bromoform) 1
Dichlorodi f 1 uorome thane
Tr ichlorof 1 uoromethane 1-5
Number of All NURP" Samples
That Reported Values
Above Detection Limit/
Number of Samples
Analyzed for Compound
4/41
6/41
2/41
16/41
0/41


0/42
0/42
0/42
0/42
0/42
0/42
1/42
0/42

0/41
0/41
0/41
0/41
0/41
0/41
0/41

0/40

19/40
12/40

4/40
0/40
5/40
1/40

17/40
5/40
6/40
0/40
0/40

2/40
6/40
7/40
6/40
1/40
2/40
0/40
0/40
0/40
1/40
1/40
1/40
0/40
4/40
           2-16

-------
                                      TABLE  2-6 (Continued)
                              NATIONAL URBAN RUNOFF PROGRAM (NURP)
                               PRIORITY POLLUTANT  SAMPLING RESULTS
      Pollutant
                              Range of Pollutant Concentrations
                                     In NURP* Storm Water
                                   Samples That Were Above
                                    Detection Limit  (ug/t)
                           Number of All NURP1 Samples
                              That  Reported Values
                             Above  Detection Limit/
                               Number of Samples
                              Analyzed  for  Compound
Monocyclic Aromatic Hydrocarbons

  Benzene
  Chlorobenzene
  I,2-dichlorobenzene
  1,3-d i chIorobenzene
  1 ,4-d i chIorobenzene
  1,2,4-trichIorobenzene
  HexachIorobenzene
  Ethyl benzene
  Ni trobenzene
  To Iuene
  2,4-dint trotoluene
  2,6-dini trotoluene
  Phenol
  2-chlorophenol
  2,4-dichiorophenol
  2,4,6-tr ichlorophenol
  Pentach I oropheno I
  2-ni trophenol
  4-n i trophenol
  2,4-dini trophenol
  2,4-dimethyl phenol
  p-chIoro-m-cresoI
  4,6-d i n i tro-o-cresoI
 1-13
 1-3
 1-3

 6-9


 2-8
2-22
  10

3-H5

 1-19


 1-2
17/41
 5/41
 0/41
 0/41
 0/41
 0/41
 0/41
 8/41
 0/41
16/41
 0/41
 0/41
 4/41
 2/41
 1/41
 0/41
11/41
 0/41
 4/41
 0/41
 0/41
 2/41
 0/41
                                          2-17

-------
                                  TABLE 2-7
                        RANGE OF CHEMICAL CONSTITUENTS
                           FOUND IN  20 PEAT SAMPLES
                           FROM THREE  CANADIAN  BOGS
PARAMETER
UNITS
      RANGE
Sample Moisture

METALS (total)
aluminum (Al)
antimony (Sb)
arsenic (As)
barium (Ba)
beryllium (Be)
boron (B)
cadmium (Dc)
chromium (Cr)
cobalt (Co)
copper (Cu)
iron (Fe)
lead (Pb)
lithium (Li)
mercury (Hg)
molybdenum (Mo)
nickel (Ni)
potassium (K)
selenium (Se)
strontium (Sr)
thallium (Tl)
thorium (Th)
titanium (Ti)
uranium (U)
vanadium (V)
zinc (Zn)
zirconium (Zr)

NON-METALS
carbon (C)
nitrogen (N)
phosphorus (P)
sulphur (S)
phenol
phenanthrene
pyrene
triphenylene
fluoranthene
benzo(g,h,i)perylene
benzo(a)pyrene
benzo(e)pyrene
chrysene
benzo(k)f1uoranthene
benzo(b)fluoranthene
ideno(l,2,3-c,d)pyrene
benzo(a)anthracene
 ppm
 ppm
 ppm
 ppm
 ppm
 ppm
 ppm
 ppm
 ppm
 ppm
 ppm
 ppm
 ppm
 ppb
 ppm
 ppm
 ppm
 ppm
 ppm
 ppm
 ppm
  %
 ppm
 ppm
 ppm
 ppm
 yg/L
 ug/L
 ug/L
 yg/L
 yg/L
 yg/L
 yg/L
 yg/L
 yg/L
 yg/L
 yg/L
 yg/L
 yg/L
    700-4800
          <1
          <2
         <15
       .1-.3
        7-25
        .3-1
        5-37
          <1
      1.5-13
    408-3575
        4-81
      .1-1.4
      .5-105
          <1
       1-6.5
     84-1025
         1-6
       14-80
         <.5
        1-10
     .01-.21
         1-2
        <2-9
        6-74
        9-66
       38-55
     .6-1.54
   .016-.066
       .1-.4
     .89-600
Not detected
Not detected
Not detected
   .0041-.13
   .0066-.09
   .033-.044
   .012-.066
   .029-.031
   .030-.058
   <.04-.054
  .0050-.092
Not detected
                                     2-18

-------











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-------
It  is  assumed that many  of  the compounds found  in  the  Canadian study  could
also be found to occur naturally in EPA Region VI.   Frequently,  waste  disposal
sites are  located  in low  areas which  could  be considered "swampy."  This  is
particularly  true  along the  Texas  and Louisiana Gulf Coast.   Monitor  wells
completed in these shallow zones may produce  water that is not  typical of most
ground water supplies.

Another potential  source of  low  concentrations of  constituents  is from  air
pollution.   Industrial  societies  generate large volumes  of products.   During
the manufacturing process, chemicals and/or chemical  compounds  escape  into the
atmosphere.   If  an odor exists, then the  chemical is either dissolved  in the
air or  is  suspended  as  a mist or  attached to a dust particle.   Rain falling
through the  atmosphere  can adsorb  these chemicals directly, or  can  settle the
dust out  of  the  atmosphere  to the ground surface  where further leaching  by
rain can  occur.   The fact that water can  absorb  chemicals from discharges  to
the atmosphere has been  known for  decades.   In the  latter 1870's, the Louisi-
ana Board  of Health  reported  that  cistern water in New  Orleans  was  contami-
nated with  ammonia that  was  escaping from  the vents of  pit  privies.    More
recently, analysis of travel  blanks collected in odoriferous parts of  petro-
chemical  plants  has  detected chemicals  produced  at the  plant.    Laboratory
blank results, especially  for methylene chloride, suggest that vapors  in the
air can  be readily absorbed  into  water.   Acid rain is  another  good  example.
Accordingly,  when  one finds  volatile chemicals  in  low concentrations  in the
shallow ground water  in  industrial  areas,  there  may  be more  than one  possible
answer as to their source.
                                     2-21

-------
SECTION 3.0  INVESTIGATIVE TECHNIQUES

-------
                         3.0  INVESTIGATIVE TECHNIQUES

The  purpose  of  investigating  both  inactive  and  active waste  disposal  sites
includes  (1)  the assessment of the  potential  environmental hazards,  (2)  the
determination  of how  much  environmental  damage  has  occurred,  and   (3)  the
development  of corrective  measures  and/or changes  in  site management  prac-
tices.  Each waste disposal site must be evaluated individually because of the
geologic  and  hydrologic variations  and  the  variety  of the wastes they  con-
tain.   Although no one  standard  investigative approach is  applicable in all
instances, some general procedures can be followed.

Initially it is useful to assemble all the available data about the particular
waste disposal site, including:

          1. Physical  location  and  boundaries  of  the   site  from
             plats,  aerial  photographs  and  topographic  maps,  and
             interviews with employees of the plant.
          2. Type  of  site,  i.e.,   landfill,   surface  impoundment,
             landfarm and chemical analysis of the waste.
          3. Area and depth of site
          4. Length of time the site was active
          5. Original design characteristics  of the site
          6. Method of site closure, if inactive
          7. Existing environmental monitoring system.

The  investigation  of an  active  site will be  greatly aided by any available
knowledge about  the nature, variety,  and  quantity of  wastes  disposed in the
site, the physical and chemical characteristics of each waste,  and the methods
of disposal.    Abandoned  sites where  waste  types and  quantities are unknown
create additional problems for the investigator.

3.1  BACKGROUND DATA
Before  beginning  a field  investigation, all  available  background data should
be collected and reviewed.   The  following  is  a partial  breakdown of available
data and sources.
                                      3-1

-------
3.1.1  Soil Data
A good  source of soils data  is  the  U.  S. Soil Conservation  Service  (SCS), a

federal agency with offices in each county and a main office for each state.


Published  soil   reports  exist  for  numerous  counties  in  Region  VI.   These

reports,  which  provide maps,  textural,  drainage,  and other  information for

each area are available from the SCS at the address below:


          U. S. Soil Conservation Service
          Soil Scientist Department
          101 South Main Street
          Temple, Texas  76501
          Phone:  (817) 774-1261

          U. S. Soil Conservation Service
          Soil Scientist Department
          Room 5423, Federal Office Building
          700 W. Capital Street
          Little Rock, Arkansas  72201
          Phone:  (501) 378-5410

          U. S. Soil Conservation Service
          Soil Scientist Department
          3737 Government Street
          Alexandria,  Louisiana  71302
          Phone:  (318) 473-7757

          U. S. Soil Conservation Service
          Soil Scientist Department
          USDA Agricultural Center Building
          Stillwater,  Oklahoma  74074
          Phone:  (405) 624-4448

          U. S. Soil Conservation Service
          Soil Scientist Department
          517 Gold Avenue SW, Room 3301
          Albuquerque, New Mexico  87102-3157
          Phone:  (508) 766-1844

Most of these reports  are  also  available for viewing at each state's agricul-

tural  departments.    The  local  county  Agricultural  Extension  Agent's office

also keeps  soils  reports for  the county in which they are located.   For  those

areas for which soils  reports are not published, soil groups have usually been

mapped  on  aerial  photos.    These are  generally  available  at  the  local  SCS

office and  can be traced or reproduced.
                                      3-2

-------
Another  source  of  soils  data  is  the Agronomy  or Soils  Departments of  the
agricultural  schools  in each state.  Access  to  this  data can usually be  ob-
tained by  contacting  the  department head or by  contacting  the State  Coopera-
tive  Extension  Services  office  located on  the  campus  of  the  university.
County  and State  Engineering  Offices,  the Department  of Transportation  of
Highway  Departments of each  state,  and  local  drillers  that  have worked  on
construction  projects,  or  have drilled  water  wells  in  the  area, can  often
provide  information on  the  soils and also on sources of  information  about  an
area.

Soils data  may not be  directly applicable  to ground water  studies;  however,
they generally give some clue as to the underlying geology.

3.1.2  Boring Inventory
In  most   industrial  complexes,  numerous soil  foundation  borings have  been
performed.    A  contractor  seldom  constructs a  building without  substantial
soils data.  Although soil samples from these borings  may not have been tested
for permeability and other  desired  parameters, at  least  the borings will help
determine  the shallow  stratigraphy.   This  data is normally  on file in  the
plant office,  or  copies can be obtained from either the  soil  testing firm or
the construction contractor.  For large structures, borings to  100 feet may be
avai Table.

Soil  borings  were  conducted  prior to  construction  of  many  existing  waste
storage  or  disposal units.    For  a  landfarm, soil borings may have been con-
ducted to determine the shallow stratigraphy and to classify soil types.   Soil
borings  may have  been  conducted for areas  now covered by tanks or a drum
storage  area.   For  landfills,  borings  may  have been conducted  to determine
stratigraphy  or  to  sample the soil  to determine  its  bearing capacity, perme-
ability, and so forth.

For roads,  bridges,  overpasses, or  riverways bordering the  site of interest,
boring records  should  be on  file at  the city or  county  engineer's office or
highway department office.
                                      3-3

-------
3.1.3  Geology

The state geological  agencies  have  numerous  geologic  maps,  at several scales,

available for  purchase.   They  also carry published  reports  on  specific geo-

graphic  areas,  with  more  detailed  information  concerning  the  geological,

hydrological,  and  other  aspects of  those  areas.    Their  phone  numbers  and

mailing addresses to use when ordering publications are listed below:


          Arkansas  Geological Commission
          3815 W. Roosevelt
          Little Rock, Arkansas  72204
          Phone:  (501) 663-9714

          Louisiana Geological Survey
          P. 0. Box G
          Baton Rouge, Louisiana  70893
          Phone:  (504) 342-6754

          New Mexico State Bureau of Mines and Mineral Resources
          Socorro,  New Mexico  87801
          Phone:  (505) 835-5011

          Oklahoma  Geologic Survey
          830 Van Vleet Oval, Room  163
          Norman, Oklahoma  73019
          Phone:  (405) 271-2555

          Bureau of Economic Geology
          Box X, University Station
          Austin, Texas  78713-7508
          Phone:  (512) 471-7721


In addition,  local  geologic societies, universities  and  the  11.  S. Geological

Survey have  available data on local geologic conditions.  The U. S. Geological

Survey offices  frequently contain  unpublished  reports  or geologic/hydrologic

observations made by employees.  These are frequently filed by the county.  To

gain access  to these files you must travel to the USGS offices and review them

as they are  NOT cataloged.


Another source to consider for regional and site-specific geologic information

is the geologic  report submitted to  regulatory  agencies,  as  part of a  permit

application  or other  reports,  by  industries  which may  be  near  the  site of

interest.   As an example,  there are three refineries  in  El  Paso, Texas that
are adjacent  to  each  other.   Information available for any two of three sites
                                      3-4

-------
could  be  extrapolated  to  the third site  to give  a  general overview  of the

geologic  and  hydrologic conditions which  could  be expected to  occur  at that

site.   In fact,  all  three sites have conducted numerous  geologic  and  hydro-

logic  investigations,  and  the  sharing  of  some   information,  such as  water

levels  or boring  logs,  has enabled each  company  to  achieve a  better  under-

standing of the hydrogeologic conditions in the area.   In addition to geologic

reports on  industrial  complexes  which may  be located  nearby, the state health

departments maintain  permit applications for sanitary landfills.   These per-

mits have geologic/hydrologic reports that frequently cover large areas.


3.1.4  Ground Water Data

The  state water  regulatory agencies have numerous  publications  concerning the

availability  and  quality  of  ground  water.   All   water  related reports and

general  information  are  available  upon   request at  each  agency.    Their

telephone numbers  and  addresses  are listed below:


          Arkansas Department of Pollution Control  and Ecology
          8001 National Drive
          P. 0. Box 9583
          Little  Rock, Arkansas  72209
          Phone:   (501) 562-7444

          Louisiana Department of Environmental Quality
          Office  of Water  Resources
          P. 0. Box 44091
          Baton Rouge, Louisiana  70804-4091
          Phone:   (504) 342-6363

          New Mexico  State  Engineer
          Baton Memorial Building, State Capital
          Santa Fe, New Mexico   87503
          Phone:   (505) 827-6110

          Oklahoma Water Resource Board
          100 N.  E. 10th Street
          P. 0. Box 53585
          Oklahoma City, Oklahoma  73152
          Phone:   (405) 271-2555

          Texas Water  Commission
          P. 0. Box 13087,  Capitol Station
          Austin,  Texas  78711
          Phone:   (512) 463-7834
                                      3-5

-------
Data on  public water supply wells  can  frequently be obtained from the  State
Health  Departments.    In  some areas,  underground water  districts  have  been
formed.  Where applicable, these  agencies have large  volumes  of  data on  ground
water resources.

Another  valuable  source  of  ground  water data is  the data  supplied by facili-
ties which  have  filed  permit  applications  with  various regulatory agencies,
which  are  located  near  the  site  of  interest.   This  data  is  often  public
information.  One good source for permit applications and  related  files  is the
central  records room of each agency.

3.1.5  Aerial Photos
Aerial  photos  are helpful aids  for  locating faults  and describing both  soil
and geologic  conditions.   They are also useful for  preparing base maps.   The
yellow pages  of most  city phone  books  list  aerial photographs  for sale  in the
area.

Aerial   photographs   can  be   used  to   review  a site   history   with   time.
Frequently,  photographs  are  available   for  a  number  of  years,  occasionally
predating  the  site   itself.   In  one   instance  in  the  Texas Gulf  Coast,  a
windmill was obvious from an old  photograph.  A later photograph  shows an acid
pit had  been constructed on top of  the  old well.

3.1.6  Landsat Image Data
When available, Landsat  images can be  surveyed  for a regionwide  assessment of
possible  structural  controls on ground water  flow.   The method employed  in
this assessment  is  to view  the  images  repeatedly  for through-going,  straight
linear  features.   These features,  termed lineaments, are defined  as  being  of
endogenetic origin (that  is, structurally controlled) and  consist  of  a natural
pattern  of  tones, textures,  and  contours that  are straight,  linear,  and more
or  less continuous,  have definable  end points  and  lateral  boundaries  (high
length/width ratio), and  hence a discernible azimuth.
                                      3-6

-------
Lineaments viewed on Landsat images provide a perspective not gained  from low-
altitude aerial photography or on-ground surveys of structural  grain.   This is
because of  the synoptic overview  provided  by the satellite  image, whereby  a
standard 29-inch' image allows one to survey an area of more than 30,000 square
kilometers at  one time.  Such  an  overview  allows  features to be seen  that are
not discernible  at  a larger scale.  Used  in  concert  with  more  detailed,  low-
altitude  surveys  and ground investigations,  the  structural  grain of  an  area
may be  characterized.   The use  of  Landsat  or  air  photographs  for  possible
controls on ground  water flow  works  best  in those areas  where competent rocks
crop out  at  the ground surface.   Contamination studies  in limestone  terrains
such as the Central Texas Edwards limestone cannot be conducted without them.

3.1.7  Additional Sources
In addition to the  above list, local  universities, Councils of Government, and
the U.S.  Geological Survey have  large  volumes of data  available to  the  pub-
lic.  Details  on  specific  waste  handling  and  disposal units and their history
can often be obtained by conversations with plant personnel.

3.2  FIELD INVESTIGATIVE TECHNIQUES
Once  background  data  have been  accumulated, site-specific   information  is
needed  to  properly assess  the  problem.   The data needed  includes:   depth to
water;  types  and permeabilities of  soils;  the type, depth,  and  thickness of
water-bearing  material; direction  and  velocity   of  ground  water  flow;  and
chemical  quality  of the ground water.  This  information can be obtained  by  a
variety of field investigative techniques.

3.2.1  Geophysical  Methods
Several geophysical methods can be employed  to assess  subsurface conditions.
While there are numerous geophysical tools used in exploratory investigations,
the most  common  are resistivity  and  electromagnetics.   These methods  are used
in conjunction with exploratory  methods of direct observation and measurement
such as exploratory drilling, monitor wells and lysimeters, tensiometers, cone
penetrometers, and  soil gas/vapor monitoring.
                                      3-7

-------
3.2.1.1  Earth Electrical Resistivity Surveys
Resistivity surveys  can  be  utilized  in a number of  applications  in hydrogeo-
logic  investigations.    They  are most  useful  in  shallow applications  where
preliminary  data are  required on  subsurface  stratigraphy  or shallow  water
quality.  They can  also  be  utilized  to  supplement  data obtained from existing
soil borings or monitor wells.

Resistivity is a  fundamental  property of material  and  can frequently  be used
to  characterize  that  material.   The  success  of  the  electrical  resistivity
method  for  subsurface  investigations rests  on the fact that  earth materials
are good conductors  of current  in proportion to  their content of (1) water or
moisture  and   (2)  dissolved  ions.    Thus,  massive  rock  formations,  such  as
basalt  or dolerite,  are  poor conductors (show high  resistivity)  because they
contain little moisture.  Clean  sands  and  clean  gravels are  also poor conduc-
tors because even when saturated with water, the water tends to be relatively
low in  dissolved  ions.  In contrast, moist  clays  and clay soils  contain both
water  and  dissolved ions,  and  they  are good conductors  (low resistivity ma-
terials) .

Electrical  resistivity of  various rocks  and sediments exhibits  great varia-
tion.   Tables  3-1  and 3-2  list characteristic  resistivities  for  various ma-
terials.   If  the quality of  water in the  zone of  saturation is not constant,
or  if  it  is highly  conductive, then  these values  may vary greatly from those
shown.

Resistivity surveying  is performed  by  introducing a direct   current  into the
ground  via two electrodes.  Low frequency (<1 Hz) current is  typically used to
minimize  undesirable  interferences   (i.e., electronic noise)  caused  by small
variations in earth  resistivity near the ground surface.  The change in poten-
tial  is measured  between another pair of  electrodes.   If  the four electrodes
are arranged  in  any of  several possible configurations or patterns, the cur-
rent and potential measurements can be used to  compute the resistivity associ-
ated  with  a given  configuration.   By  changing  the distances  among  the four
electrodes within a  given configuration, or by  relocating the entire electrode
array  at  another ground position,  a  series of  resistivity  measurements are
made to complete a survey.
                                      3-8

-------
                                   TABLE  3-1

                      RESISTIVITIES OF  DIFFERENT ROCK AND
                                SEDIMENT TYPES
Rock Type
Igneous and Metamorphic Rocks
Granite
Diorite
Dacite
Diabase
Lavas
Gabbro
Basalt
Schists
Tuffs
Graphite shcist
Slates
Gneiss
Marble
Skarn
Quartzites
Sedimentary Rocks
Consolidated shales
Argil lites
Conglomerates
Sandstones
Limestones
Unconsolidated wet clay
Marls
Clays
Alluvium and Sands
Resistivity

3 x 102
104
2 x 104 (wet)
20
102
103
10
20
2 x 103
10
6 x 102
7 x 104
102
3 x 102
10

20
10
2 x 103
1
50
20
3
1
10
Range (ohm-m)

106
106

5 x
5 x
106
107
104
105
102
4 x
3 x
2 x
3 x
2 x

2 x
8 x
104
6 x
- 107
200
70
100
800





107
104





107
106
108
108
108

103
102

108





Source:  (Telford et al., 1976)
                                      3-9

-------
                               TABLE 3-2

                Resistivity Values for Selected Sediments
SEDIMENT TYPE
                                         Resistivity (ohm-cms)
0   200   1000   2000   3000  30,000  100,000  300,000
Sediment Type

Clay Marl (CH)

SiHy/Sandy Clay (Cl)

Sandy Soils (Sm), (Sc)

Gravels

Dry Sand or Gravel
Fractured Bedrock

Massive Bedrock
Very Dry Sand or Gravel
                                     3-10

-------
If the measurement  of  resistivity  is made  over  a  semi-infinite space of homo-
geneous and  isotropic  earth, then a value for true resistivity  is  obtained.
Practically,  however,  no measurement of  the  geologic  environment meets  this
ideal case,  and  heterogeneous and  anisotropic conditions  are  normally encoun-
tered.  Hence, the  value computed is  more appropriately termed apparent resis-
tivity.   Apparent  resistivity is  a  function  of the electrode configuration;
the  distances  between  electrodes;  true resistivities;  topographic  irregular-
ities; and subsurface characteristics,  such as strata thickness, angle of dip,
and  anisotropic properties.

Electrode Configurations
In principle,  any electrode configuration could be used;  however, only about
six  patterns are  known to be in common  use, since computations and data inter-
pretations  are otherwise  difficult.   Two  electrode  configurations  commonly
used  to   conduct  electrical  resistivity  surveying are  the  Schlumberger  and
Wenner arrays  (Figure  3-1).   In  both  arrays, the four electrodes are placed
along a straight  line  on the ground  surface,  as shown.  With the Schlumberger
array, the  four  electrodes  are again placed  in a straight line  in  the order
AMNB, but with distance  AB > 5 MM.

The  Wenner Array  is particularly well suited for soil and pollution investiga-
tions.  The  Wenner  electrode configuration utilizes equal  electrode separation
(A)  between  potential  electrodes  (M-N)  and opposing  current  and  potential
electrodes  (A-M  and N-B).   Current  (I)  is introduced  into the subsurface at
electrodes  A and B and  forms a potential field perpendicular to the current
flow.   Voltage  drop   (V)  is measured  by  electrodes  M and  N.   The apparent
resistivity  at  each  electrode spacing  can  be calculated  by  the  following
formula:

          Pa =
where:
          Pa = apparent resistivity in ohms/feet
          V  = voltage drip measured at M and N in millivolts
          I  = current applied at A and B in mi Hi amperes
          A  = electrode spacing in feet
                                     3-11

-------
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       Figure 3-1.   Electrical Resistivity  Electrode Configuration
                                3-12

-------
Resistivity Survey Types
The  two  types  of   resistivity  surveys  used  for  exploration  are  vertical
electrical  soundings and  horizontal  profiling.   The Wenner  and  Schlumberger
arrays  are particularly  suited to  sounding  investigations.   Soundings  are
conducted  by  incrementally expanding the electrode array about a fixed central
station,  while maintaining the proper distance relationships  among  the elec-
trodes.   The  voltage drop and current are measured at  each  increment.   Loga-
rithmic  increments  are typically used, and  the measured  apparent  resistivity
values  are graphed  as a function of  electrode  spacing  on logarithmic coordi-
nate paper as a sounding curve.  The  expanding spread  is  best suited for the
detection  of  horizontal  or gently dipping strata of  different resistivities.
By increasing  the separating  distance between the current  and potential elec-
trodes,  measured resistivities relate to increasingly  greater  depths.   Hence
the  method is  useful in  determining the approximate  true  resistivities  of
sedimentary strata,  as  well  as their  thickness.  Soundings  can often be com-
pleted more rapidly  if the Wenner array is used rather than the Schlumberger.

In electrical  profiling,  a fixed electrode  spacing is  chosen,  and the entire
array  is moved  laterally  along  a  ground traverse.    Resistivity  measurements
are  made  at  regular  intervals  along the  traverse.    The  field  resistivity
values are plotted as a  function of  the  distance  of each value from the start
of the  traverse.  Either the  Wenner  or  Schlumberger  arrays  is suited to pro-
filing,  as the  survey  method  seeks  to  detect  anomalous resistivities  that
exist  along  the traverse.   Profiling is best suited to  detection of steeply
dipping  or vertical  contacts,  faults, or dikes of contrasting resistivity.

Data Interpretation
Interpretation  of  the  resistivity  profile  curves  is  largely  subjective  and
consists  of recognizing  deflections  in the  curve which  are  representative  of
lateral  discontinuities  or changes  in subsurface conditions.   The procedures
developed  to  interpret  resistivity  data using Wenner or  Lee electrode arrays
can be grouped into  two categories:   theoretical and empirical.  Using theore-
tical  methods,  the  field data  (Figure  3-2)  are  plotted  for comparison  to
specially  prepared   type  curves  developed for  numbers  of  resistivity  layers
with definite  ratios of  resistivity  and thickness.    For  the purposes of many
                                     3-13

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Investigations,  two  empirical  methods, Moore's  Cumulative and Barnes1  Layer
Method are utilized (Figure 3-3).

The Barnes1  Layer Method of interpretation assumes that the  subsurface  sedi-
ments  act  as  a  set  of  horizontal  layers  in which  the  thickness of each  is
equal to the  increment  in  electrode  spacing.   Using  Moore's  Method,  the  elec-
trode spacing  is  multiplied by the  apparent  resistivity  value and the cumula-
tive values are plotted.  Slope changes in  the lines  connecting the cumulative
values generally  indicate  depth  to  subsurface sediment changes or changes  in
the  quality  of   the  ground water.    Soil   borings  in  the   vicinity of  the
soundings  graphically  displayed  in  Figure  3-3  revealed  a fairly  consistent
clay strata with  a high moisture content at approximately 15  feet.

Earth resistivity surveys are particulary useful  in determining lateral  migra-
tion  from   liquid waste  disposal  sites  constructed  in  alluvium  sediments.
Figure 3-4 was constructed using resistivity values  obtained at a  constant
electrode  spacing of 18  feet.   The  survey  indicates  that  saltwater is migrat-
ing from the pond in a southeasterly direction.

There  are  many sites  where resistivity surveys are  not  suitable.   In  areas
where  the  quality of the  liquid waste or leachate  is of similar quality  to
natural  ground water  (in  terms  of conductivity),  then  it  is  difficult  to
determine  waste   fronts.    In  many  industrial  complexes, the occurrence  of
underground  pipelines,  overhead  electrical  lines,  and paved  areas  decreases
the  efficiency of  resistivity  surveys.   In  addition,  where  the  subsurface
strata is  not  uniform, the method has major limitations.

Interpretation of the Schlumberger sounding survey can be accomplished through
the use  of a computer program that  employs  linear filter  theory  to  compute a
theoretical  apparent  resistivity curve for  an  initial  set  of  user defined
layer thicknesses and resistivities.  Marquardt's algorithm is then applied to
the user defined model, modifying  the  model iteratively until it  produces a
match with  the field curve.   The procedure  assumes that  the  earth model  is an
infinite half-space  divided into  horizontal  layers,  each electrically  homo-
geneous and  isotropic.   The model parameters  include  the  resistivity and the
thickness  of   each  layer.   The  bottom or  deepest  layer  is  assumed  to have
                                     3-15

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                                                 3-16

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-------
infinite thickness.   Figure  3-5  shows  an  example  of  a  field  data curve (solid
line) generated  by  hand,  and the computer modeled curve  (dashed  line)  gener-
ated for the same data.

3.2.1.2  Ground Penetrating Radar
Ground  Penetrating  Radar  (GPR)  is  the electromagnetic equivalent  of  seismic
profiling used for oil exploration,  except on a more  reduced  scale.   This non-
destructive geophysical test is a fast, relatively inexpensive way to find and
outline  subsurface  feature configuration.   The system provides  a  continuous
graphic cross-section  of  the subsurface.   GPR  components  are  portable  and the
instrumentation fits  into a station  wagon, pickup or  van.

The power converter  is energized by  a  12-volt  car battery or AC generator and
powers  the  pulse generator in the  control  unit.   This generates a two nano-
second  pulse,  50,000  times  per second,  transmitted into the  ground  by the an-
tenna.

After transmission,  the antenna  "listens" for  200  nanoseconds as  it  detects
and amplifies  signals reflected  from  the  boundaries between media  with con-
trasting  electrical   properties.   The  greater the  electrical contrast,  the
higher  amplitude of the reflected signals.

As the  antenna is  towed along the ground,  a continuous stream of reflections
is printed on  the graphic recorder and stored on magnetic  tape.

Some uses for  the GPR  include:

          •  Subsurface void detection
             Profile  the depth to bedrock
             Establish  soil  horizon  continuity  along  a route  to
             minimize  expensive drilling operations
          •  Measure  the  thickness of  weathered bedrock in mountain-
             ous terrain.
          •  Locate  buried utilities,  e.g.,  pipelines,  sewers  and
             electrical conduits.
                                     3-18

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Horizontal  survey  control  is required.   Each  time the GPR antenna  crosses  a
known  location,  the  operator  electronically marks  the radar  profile.    The
marks  are permanent  references  to ground  control and  the distance  between
marks  is  interpolated.   On  a smooth,  level  ground  surface,  these marks may.be
200  feet  apart.    On  rough  roads or cross  country,  where the  survey  vehicle
speed may vary, more closely spaced control  is  needed.

The GPR  antenna  scans a path about 16 inches wide.  With no data between the
lines,  subsurface  configuration  can   be  approximated   only  by  straight  line
correlation between profiles.  Large features which do not  intersect adjacent
profiles  can  cause significant  errors in  subsurface  feature  interpretation.
This  technique,   as with  resistivity, has  restricted  use in  petrochemical
plants and other areas where numerous  surface and buried structures exist.

3.2.1.3  Magnetic  Surveys
It  has been known for more  than  three centuries that  the earth  behaves  as  a
large  and somewhat irregular  magnet.   The  geomagnetic field   is  composed  of
three  parts, so far as exploration geophysics is concerned:

          1. The  main field which,  although not  constant  in   time,
             varies relatively slowly, and is of internal origin.
          2. The external field,  a small  fraction  of the main  field,
             which  varies  rather rapidly,  partly cyclically,   and
             partly  randomly,  and which  originates outside  of  the
             earth.
          3. Variation of the  main field, usually much smaller  than
             the main  field, relatively  constant in time and  place,
             and  caused  by  local magnetic  anomalies   in  the   near-
             surface  crust  of  the earth.   These variations are  the
             targets  in magnetic surveys.

Magnetic  anomalies  are caused  by  the  amount of  magnetic minerals contained in
the  rocks,  i.e.,  magnetite, pyrrhotite,  and  a  few others.  Although  in many
cases  the magnetization  of  rocks depends mainly upon  the  present strength of
the  ambient geomagnetic field  and the magnetic  mineral  content,  in  general
this is not true.   In practice, residual  magnetism, or normal  remnant magneti-
zation, often  contributes to the  total magnetization  in rocks, both in ampli-
tude and  direction.  This  fact  is very  important, particularly  in  the areas
where  several  intrusive and  extrusive rock types of different age occur.
                                     3-20

-------
The  degree of  magnetization,   I,  of rocks  for induced  polarization  is  the
product of the susceptibility,  k, and the magnetizing field,  H.   That  is:

                                   I  = k*H.

The  polarization  produced  by magnetization  in the earth's geomagnetic  field,
H,  has  an intensity  range of   about  30,000  gammas  to  60,000 gammas, with  a
common value of about 50,000 gammas.

To  the extent  that the magnetization of the rock  is  caused  by  simple  induced
magnetization by the earth field in its present direction, anomalies caused by
such magnetization will have variation with  latitude.  Polarization and  polar-
ization contrast among rocks control  the magnitude  of magnetic anomalies.   The
susceptibility  of rocks  is a  measure  of  their  magnetite   (FejO^)  content.
Magnetite  is  highly  ferromagnetic  and by far  the  most  common of the  magnetic
minerals in rocks.

The magnetic field survey entails the measurement of  variations in the earth's
geomagnetic  field.   The  survey is carried out  by taking measurement of  the
magnetic  intensity,  usually in straight lines  where possible,  across  areas
previously selected  by the  interpretation of  the  aerial or  satellite  photo-
graphs or  on a  survey  grid across waste disposal sites.  A magnetometer is
used for magnetic surveys.  This instrument measures  the vertical component of
the  total  magnetic  field  in gamma units.  A  block diagram  showing a  fluxgate
magnetometer is shown in Figure 3-6.

The  points  of  measurement  (magnetic  stations)   are  distributed  along  each
traverse or grid  line  at  regular intervals,  i.e.,  10 to 30 feet.  The station
interval will  depend either on the  magnitude of  the magnetic  anomaly to be
investigated, or  on  the degree  of  accuracy  required.   The magnetic intensity,
gamma, is  plotted  against  distance traversed.   The resulting magnetic profile
is  examined for anomalies on the earth's geomagnetic  field.

The  magnetic  profile  is  qualitatively  interpreted by  examining  the  relative
locations  and  amplitudes  of the positive and  negative  portions  of the  curve,
                                     3-21

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and  by  inspecting  the  sharpness  of any anomalies  produced  (Figure 3-7).   A
magnetic anomaly  may  be created by variations in the  magnetic  susceptibility
of  the  subsurface  material,  or by  a change  in the  relief  of the  magnetic
basement.

Various rock  types possess very different magnetic  susceptibilities,  and are
thus easily distinguished by using the magnetic method.  For  example,  sedimen-
tary rocks  generally  create a  magnetic  field  of relatively  low and  constant
magnetic  intensity.  Dolerite  (dikes  and  sheets)  produces  a  magnetic  field
which,  due  to  the distribution of magnetite,  can  be  of  high intensity and
variable direction.   The  magnetic  field  created  by  extrusive  basalt is gener-
ally  lower  than  that of dolerite, but  much higher  than  the  magnetic  field
created by  sedimentary  rocks.   The magnetic intensity  created  by  rock can be
reduced by  destroying the magnetite content  of  this rock.   Magnetite can be
destroyed by weathering processes of the rock.

In  order  to measure the daily  variations of the magnetic  field,  a monitoring
base station should be established.  The maximum daily variation of the verti-
cal  component  of  the  total  magnetic  field  should  be  measured and recorded.
Corrections to the  field data for these daily variations are  not necessary, if
the  anomalies  of  interest are  considerably  larger  than the  maximum  recorded
daily variation.

Besides the daily  variations of  the  magnetic  field associated with  electric
current generated  in the  ionized layers of the outer atmpsphere, the following
variations  of the  magnetic field take place:
          1. A  secular  variation  (long term variation, on the scale
             of years, of main magnetic field);
          2. A  short  term  regular  periodic variation  of external
             field;  and
          3. Irregular transient fluctuations (magnetic storms).
                                     3-23

-------
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FROM SEVAN (1983)
                     Figure 3-7.  Example of Typical Magnetic Anomaly
                                    3-24

-------
Interpretation of Data
The end  result  of a magnetic survey is a set of magnetic profiles.  The  pro-
files  are  plotted at  a scale and  vertical  exaggeration suitable for  inter-
pretation.   The  method of  interpretation  involves  matching field  anomalies
with simple  geometrical shapes.   These  anomalies  can be displayed  as  single
traverse  profiles,  as  magnetic  contour maps  or as  three  dimensional  plots
(Figure  3-8).   Although magnetic exploration  techniques  are most useful  for
ore  body determination, or  ground  water  exploration in basement rock  com-
plexes,  they have been  adapted  in  recent  years  to  contamination studies  at
waste disposal sites where drums  of  waste are suspected  to have  been  buried.

Magnetic  surveys  at waste  sites  are normally  conducted  similar  to geologic
exploration.  The site  is normally laid out in traverses  and  readings taken at
regular  intervals.  The data are  then used  to construct  contour  maps  of magne-
tic intensities.  Figure 3-9  is a magnetic  contour map  which was prepared for
a Superfund  site  in Arkansas.  The magnetic high on the  north side of the site
corresponded to an old  strip  mine which  had  been  filled  with trash and indus-
trial waste.  The area  in  the middle  of the site corresponded to the southern
edge of  an  old evaporation  pond  which had  been  located  by  using air  photo-
graphs.   These  magnetic highs were  later targeted for exploration.  Numerous
trenches were excavated in both  areas.  In  the  northern  area,  numerous drums
of solid  industrial waste  were found  along  with  typical  municipal  metals such
as refrigerators  and  appliances.  At the southern location,  numerous  crushed
drums were  found  which  at  one time  contained  liquid  solvents and  other waste
organics.    In areas  of the  site where  no  magnetic  anomalies  were  detected,
very little  waste was found.

3.2.2  Exploratory Dri11 ing
Exploratory  drilling is key to the characterization of the site.  The drilling
program  seeks to  define the geology beneath the  site which,  in turn,  identi-
fies ground  water flow  paths.  This  definition is obtained from  the collection
of subsurface  soil  samples for visual classification and laboratory analysis
or obtained  from  running downhole geophysical  logs.   Additional means  to help
define the  subsurface  would  include drilling observations such  as changes in
drilling  rates,   rig  chatter, lost  circulation,  etc.   The   drilling  program
ultimately  provides  information  on  the correlation  of  the  subsurface units
                                     3-25

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between  boreholes,  identification and  physical  properties  of the  confining
beds and permeable zones, and lithologic changes  within a given unit.

An exploratory  drilling  program  usually is a phased process.   In  areas  where
the  subsurface  conditions  are  unknown,  several phases  of drilling  may  be
required.   The initial  number  of boreholes  should  be sufficient to  provide
enough  information  so a more detailed  drilling  program can be devised.   The
overall  geologic  picture must  be evaluated  to  determine  this  number.    The
total number  and  depth of subsequent borings will be  better defined once  the
drilling program begins.

The  number of  boreholes required  to  define  the subsurface  conditions  are
dependent upon the site conditions.   A simple geologic  environment  with thick,
relatively  continuous,  horizontal beds  can  be  characterized  with  relatively
few boreholes.  However, in areas with dipping strata or in coastal  areas with
numerous facies changes  and  lithologic  zones  of  varying  materials,  the number
will be  larger.

3.2.2.1  Drilling Methods
A  variety  of  drilling methods have  been successfully applied  to  exploratory
drilling as well as monitor well  installation.  Table 3-3 lists the advantages
and disadvantages of the most commonly used methods.

The most  suitable  drilling  method for  any situation requires  a site specific
evaluation  and  selection.    Several  factors  relating  to the  investigation
objectives and site conditions require consideration.

          -  The type of formation material to be drilled through.
          -  The total depth of the drilling operation.
          -  Depth to water table.
          -  The type of contaminants expected.
          -  The surface conditions at the drilling site.
          -  The design  and depth of  screen  placement  of  the monitor
             well, if it is to be installed.
                                     3-28

-------
                                                        TABLE  3-3
                                                    DRILLING METHODS
     TYPE
                                       ADVANTAGES    DISADVANTAGES
Hoi low-stem      •  NoDrillingfluidis  used, eliminat i ng
auger              contamination  by  drilling fluid additives

                 •  Formation  waters  can  De sampled during
                   dri I I ing by  using  a screened  auger or
                   advancing  a  well  point ahead  of the augers

                 •  Formation  samples  taken by split-spoon
                   or  core-barrel methods are highly accurate


                 •  Natural gamma-ray  logging can be done
                   inside  the augers

                 •  Hole  caving  can be overcome by setting
                   the screen and casing before  the augers
                   are removed

                 •  Fast

                 •  Rigs  are highly mobile and can reach
                   most  dr i I I i ng  si tes
Can be used only in unconsol idated
materials

Limited to depths of 100 to 150 ft  (30.5
to 45.7 m)
Possible problems in controlling
     heaving  sands

May not be able to run a complete suite
of geophysical logs
Direct rotary    •  Can  be  used  in  both  unconsol idated and
                   consolidated  formations

                 •  Capable of drilling  to any  depth

                 •  Core samples  can  be  collected

                 •  A  complete suite  of  geophysical  logs can
                   be obtained  in  the open hole

                 •  Casing  is not required during  drilling

                   Many options  for  well construction

                 •  Fast

                 •  Smaller rigs  can  reach most driI I ing sites

                 •  Relatively  inexpensive

                 •  Formation samples taken by  split-spoon,
                   Shelby  tube or  cores are  very  accurate
                   and  fast
Drilling fluid is required and
contaminations are circulated with the
fluid

Dr iI  I i ng fIu fd mi xes with the format i on
water,  invades the formation and  is
sometimes  difficult to remove
Organic fluids may  interfere with
bacterial analyses  and/or organic-related
parameters
During drilling, no  information can  be
obtained on the  location of the water
table and only  limited  information
on water-producing zones
                                                      3-29

-------
                                                        TABLE  3-3
                                               DRILLING METHOD (Continued)
     TYPE
ADVANTAGES
DISADVANTAGES
Air rotary       •  No  water-based  drilling  fluid  is used
                •  Capable  of  drilling  to any depth

                ป  Formation  sampling by cuttings  is excellent
                   in  hard, dry  formations

                "  Formation  water  blown out of the hole
                   makes  it possible to determine  when the
                   first  water-bearing  zone  is encountered

                •  Field  analysis of water blown from the
                   hole can provide information regarding
                   changes  for some basic water-quality
                   parameters  such  as chlorides

                •  Fast
                             Casing  is required to keep the hole open
                             when  drilling  in  soft, caving formations
                             below the water  table

                             When  more than one water-bearing zone
                             is encountered and hydrostatic pressures
                             are different, flow between zones occurs
                             during  the time  drilling is being
                             completed and  before the borehole can be
                             cased and grouted properly
                             Air must be filtered to prevent blowing oil
                             in the hole

                             Can only be used in consolidated formations
Cab Ie too I       •  On I y  smaI I  amounts  of  dr iI Ii ng  fluid are
                   required  (generally water  with  no
                   add i t i ves)

                 •  Can be used in  both unconsol idated and
                   consolidated  formations;  well suited for
                   extremely  permeable formations
                 •  Can  drill  to depths  required  for most
                   mon itor i ng we I Is

                 •  Highly  representative  formation samples
                   can  be  obtained by an  experienced driller

                 •  Changes  in water  level  can  be observed

                 •  Relative permeabilities for different
                   zones can  be determined by  skilled drillers

                 •  Rigs can reach  most  drilling  sites

                 •  Relatively inexpensive
                             Minimum casing size is 4 in. (102 mm)

                             Steel  casing must be used

                             Cannot run a complete suite of
                             geophysical  logs

                             Usually a screen must be set before a
                             water sample can be taken

                             Slow

                             Cannot cement upper casing although
                             seals are usually good
        Adapted from Manufacturer's Literature Provided by Johnson
        Mon i tor ing Wei Is
                            Screens, Materials  Selection  for  Ground Water
                                                      3-30

-------
Regardless  of the  drilling  method chosen,  good sediment  samples should  be
obtained.   Although cuttings  can be used, undisturbed  samples  are preferred.
The choice of drilling method is contingent upon a number of factors including
depth, ' materials  of  construction of  the  well,  preferred  water  sampling
methods, sediment type,  and others.  Each  method  has  its applications, and as
long as the advantages and limitations  of each method  are understood,  there is
no inherent, preferred method.

3.2.2.2  Logging Techniques
The  logging  of boreholes enables  the  site to be characterized  by describing
the  lithology  and  correlating the stratigraphy of one  borehole  with  another.
The  subsurface can  be  logged  in  several  ways.   The  subsurface can be visually
described  from grab  samples  of  the  drilling mud  returns  or  from extracted
samples  using Shelby  tubes,   split-spoon  samplers, or  rock coring  devices.
Alternatively,  indirect means  of  classifying  the subsurface  can be  accom-
plished with downhole geophysical logs.

Lithologic Logging
Lithologic  sampling and logging  should be performed by  a  qualified geologist
during  the  drilling of  a borehole.  The  aim of the geologist  is  to  classify
the  subsurface soils and identify the major confining and permeable units.

Subsurface samples  can  be obtained  by  several  means.   Cohesive  soils, such as
silts,  clays,  and   clayey or  silty  sands,  can be sampled with  a Shelby tube.
This  provides  an "undisturbed"  soil sample  which can  be used  for laboratory
determinations  of  permeability.   Non-cohesive  soils,  such   as  sands  and
gravels, can  be  collected using  a split-spoon sampler.   Harder consolidated
sediments such as  sandstone  and limestones can be  sampled  with a rock corer.
Although not  as  precise or suitable for  laboratory  analysis, grab samples are
often taken from the mud or cutting returns.

The  sampling  frequency  is  site  specific.    In  areas  of  unknown  geology or
contamination, continuous sampling would best establish control  of the subsur-
face.   For  most  exploratory  programs,  undisturbed  samples  collected at 3-foot
intervals for  the upper 20 feet  and at 5-foot intervals thereafter are gener-
ally  sufficient  for site stratigraphy and permeability  determinations.   Once
                                     3-31

-------
the  overall   geologic  picture  is  determined  and  the  major  units  defined,
samples from  subsequent  boreholes  can be  taken  at regular 5-foot  or 10-foot
intervals depending on the complexity of  the environment.

The  lithology is described  in  the field  by  the  supervising  geologist.   The
geologist will  classify  the  soil  or rock  type and  augment  the  classification
with a description  of  the  color, plasticity,  cohesiveness,  degree  of  weather-
ing, moisture content,  and  indications  of  potential  contamination,   such  as
organic content  and odor.    Notations  on the presence of fractures,  bedding,
vugs, or cavitities, and water  bearing zones  are  also made.   This  classifica-
tion and associated descriptions are included on  the driller's log.

Several  soil   classification systems  exist,  e.g., the  Unified,  Wentworth,
AASHTO and  USDA.   The predominant  system  is the  Unified Classification  Sys-
tem.  However,  the  Wentworth Classification  System  is commonly  used by geolo-
gists.   The Unified System is outlined in Table 3-4.  The  criteria  for classi-
fication in Table 3-4 are arranged  in such  a manner that  identification can be
performed  in  the field  by visual  inspection and  simple  manual tests.   This
field method  is  described in detail in ASTM D 2488-84.   A  numerical  version of
the system (ASTM D  2487-83), based  on particle-size and  Atterberg limit tests,
is used in the  laboratory  to more  accurately classify  selected  samples and to
check the field  identification.

Field  identification  procedures   will   generally   concentrate  on  estimating
gradation  and  plasticity,  which   are  the   fundamental  criteria for  grouping
soils in the  Unified System.  Classification of  coarse-grained  soils  is based
on the gradation,  while  the classification of fine-grained soils  is  based on
plasticity.   Gradation  is  used  to  further  divided  soils  into groups  of clean
and "dirty" (soils  with fines).   The clean  soils  are further divided into well
graded and poorly graded.  The "dirty" soils are  divided  based on plasticity.

Visually determining whether the soil is  fine-grained or  coarse-grained can be
difficult, particularly  if the  coarse-grained portion is  fine to medium sand,
and the percent passing  the No. 200  sieve  (fine-grained  fraction)  is near 50
percent.   In  this   instance,  the soil will  be classified  with a modifier such
as silty or clayey  sand  or sandy clay or silt.   In marginal cases, it is best
                                     3-32

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to classify  it as  a  silty  or clayey sand  as  this will be  conservative  with
respect  to  permeability  characteristics   and,  hence,  pollution  migration.
Whether  the  modifier is  "silty"  or  "clayey" will  be based  on  plasticity
characteristics.

For a  coarse-grained  soil  which is predominantly clean, the  determination  of
whether it  is  well  or poorly  graded  is  relatively  easily determined by visual
examination and feel.  The  sample  can be  spread  across  a flat surface and the
gravel-size particles can  be felt and  moved  aside.   A  well-graded  soil  will
have  a wide  range  in grain  sizes with  substantial  amounts of  intermediate
particle sizes.

A poorly graded sand  can be identified,  in many instances,  by its feel as  well
as its appearance.  When a  wetted,  poorly  graded  sand sample is packed by the
fingertips  into the cupped  palm of the hand,  it will not  cease deforming and
moving out  ahead of  the probing fingers.   Treated  similarly,  a  well  graded
sand can be felt to densify, stiffen, and resist  penetration by  the fingers.

The determination of  whether a sample is a silt or a  clay or a silty or clayey
sand is subjective  to the  geologist  performing the classification.  Since the
difference  between silt and clay  is  not  visible  to   the  naked  eye,  field
methods of identifying the plasticity and classification of fine-grained soils
are best described  by referring  to  Table  3-5.   Even  with these  field methods,
classification  between silts  and clays  generally can only  be determined  with
laboratory testing.

Trying to  correlate  gradational  units  across a  site with  a  differentiation
between a  clay and  silt based   upon field  determination only  is  not practi-
cal.   Even  with laboratory data to  corroborate  field  data,  correlating these
units  from  one borehole  to the  next is suspect.   It  is  best to correlate the
subsurface  stratigraphy  on a broader determination  of  relative permeability.
In other words, differentiate between low  permeability  soils such as silt and
clay and higher permeability soils such as silty  sand, clayey sand, and sand.
                                     3-34

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                                  3-35

-------
Downhole Geophysical Logging
Another means  of  determining  and  correlating subsurface units is  through  the
use of downhole geophysical logging.   Geophysical  logging  is  generally used in
conjunction with  a field  sampling program.   In ground water  investigations,
the logs are generally used for correlation and determination of  bed  thickness
but can also be used for determination of porosity and  water  saturation.

The most  commonly used  logs  are  resistivity,  natural  gamma,  and  spontaneous
potential  (SP).    In some  cases,  a neutron density  log  is run.    Figure  3-10
shows an  example  of these types of downhole geophysical  logs  compared to  the
geologic log for a site  in Oklahoma.

Resistivity logs measure the  electrical  resistivity  of  the formation by  pass-
ing  an  electric  current out  into  the  formation.   The  resulting  logs  help
define  the contact  between  resistive geologic  units  such  as  limestone  and
sandstone  and  conductive units such as clays and shales.   If  the  lithology has
been well  defined  from  the boring  program,  it  is  sometimes possible  to evalu-
ate the water  content and  salinity of a given formation.   A formation which is
either saturated with fresh water, or unsaturated, will be more resistive than
the same formation saturated with saline water.

Spontaneous potential or SP logs are  a measurement of the  electrical  potential
between a  point in the borehole and a grounded  electrode at the surface.   This
potential  is  caused by  electromagnetic  forces  in porous   or  permeable  zones.
The SP  can be  used  to  define geologic contacts, detect  permeable units,  and
give qualitative indications of the clay content within sands.  In impermeable
sediments,  the SP  will  not respond and results in what is known as  the  shale
baseline.  Deviation from  this baseline is an indication of permeability.

Natural gamma  tools measure the natural radiation within the  formation.  Since
clays usually  contain radioactive isotopes of potassium, the  clayey formations
are  indicated   by  a maximum  gamma  value.   Sands or  carbonaceous formations
generally  have little  or no  radioactivity  and  are differentiated   from  the
clays.   Therefore, the  gamma  is  a useful tool for  delineating  the  depth and
thickness  of aquitards.
                                     3-36

-------
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          3-37

-------
Not as  commonly  used as natural gamma, the neutron density  tool  measures  the
hydrogen content  of the formation.   Since  clays contain  interstitial  water,
the neutron  density log  responds  to the formation.   This tool  is  generally
used  in  conjunction with  the natural gamma as a delineator  of  clay  and shale
zones.

At  certain  sites where the  stratigraphy  is well defined,  a borehole  can  be
drilled  using  mud rotary  techniques  and  logged  from  the grab  samples  of  the
cuttings within the mud returns.  These samples can  be collected every 10 feet
until  the  approximate  depth of the  target  formation  is reached.  While this
technique provides  reasonable  accuracy in delineating, for  example,  the con-
fining  zone  overlying  a permeable  saturated zone, the  process  of circulating
mud from the bottom of the hole to  the surface introduces certain errors.

One problem  is  the  lag  time  between  the  penetration of the stratigraphic unit
by  the  bit  and when the  cuttings  reach  the surface.   Another  problem  is  the
classification of grab  samples  below  a formation which caves into the hole as
a deeper formation  is  being  penetrated.   This  will  tend to give an indication
of  a  gradation within the subsurface when  in  fact  the units may  be  well  de-
fined.   For  example, a clay zone underlying a sand can appear  at the surface
as a  sandy clay because portions of the overlying sand were either stripped by
the mud or sluffed  into the hole.

Downhole  geophysical  logs  are useful  for  delineating different  lithologic
units in the  subsurface.   Figures  3-11 and  3-12  show  examples of the drillers
log compared to the natural gamma log.  Figure 3-11  shows the depth determina-
tions of  lithologic units from the  cuttings  were more  accurately defined by
the gamma log.  (Note the silt zone indicated by the driller to be from 125 to
135 is  really  located  between  110  to 125).   The  borehole shown in Figure 3-12
was drilled  for a monitor  well  installation.   The  screened interval  was to be
placed  just  below  a clay zone known to occur  at  about  230 feet  below  the
surface.   The driller's  log constructed  from the cuttings  from  the  hole  did
not clearly  indicate the  depth  or  existence of the  confining zone.  The natu-
ral gamma  log, however,  clearly  defined the  unit  and  allowed  the  bentonite
seal  to be placed within the confining zone.
                                     3-38

-------
      WELL CONSTRUCTION
                                              GAMMA RAY LOG
  FEET
   BG
 20
 40
 60
 80
 100
120
140
160
180
200
220-
240
260l-
— 12 1/4" BOREHOLE
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  COLLAPSE
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                                                         100
         GENERAL
       STRATAGRAPHIC
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CLAYEY SILT

    SAND

 SILTY CLAY

    SAND


CLAYEY SILT


SILTY CLAY
                                                                 SAND
                                                                  SILT
                                                                  SAND
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                                                                                 20
                                                        40
            Figure  3-11. Example  of a Gamma  Ray Log  Compared  to the
                           Stratigraphic Log  Determined by the  Driller
                                                                                 80
                                                                                 100
                                                                                 120
                                                        140
                                                                                 160
                                                                                 180
                                                        200
                                                                                 220
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                                                        260
                                     3-3ฐ

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                  3-40

-------
Geophysical  logs  also  aid  in the  correlation of  subsurface  stratigraphic
units.    Figures  3-13   and   3-14  show  the  difference  between  correlating
driller's  logs units  and downhole geophysical logs.  While  the  driller's  logs
indicate a relatively non-uniform environment with units  of  varying  thickness
and  depth, the  natural gamma  logs  show  the subsurface  consists of  broad,
relatively uniform, permeable zones  that can be  correlated over  larger areas.

3.2.3  Monitor Wells
Monitor wells  are  the preferred method for determining the  concentration  and
movement of chemical  constituents in  the  saturated zone.   They can  be  used
either  to  determine  the  natural  chemistry of the ground water (as  in  back-
ground wells)  or to monitor  the movement and  concentration  of  contaminants in
the ground water downgradient of a source (as in downgradient wells).

Monitor wells  are primarily used to:

           •  Provide  access   to ground water  for collecting  water
             quality  samples,
           •  Determine the ground water chemistry,
           •  Detect contaminants  in  the subsurface  soils and water
             bearing  formations,
           •  Determine  the  area!  and  vertical  extent of   contami-
             nants,
           •  Monitor  the movement of contaminants in the  water bear-
             ing formation,
           •  Determine water  levels  in the  aquifer,  and
           •  Perform  aquifer  testing  for aquifer properties.

In order to accomplish  these objectives a monitoring  system must  be designed
to  take into  account  and incorporate a  variety of  criteria  including  the
location of the well, the  placement  of the  screen,  the  installation procedures
used, and  the  design  of the well.

3.2.3.1  Well  Location
Selection  of  monitor  well locations  is  dependent  upon ground  water  flow and
hydrogeologic  conditions  although  site access and drilling  capabilities  must
be considered  and often direct  the ultimate decisions.
                                     3-41

-------
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-------
The initial purpose of monitoring wells is  to determine  if  a  waste  facility  is
leaking.   Later  purposes  include determining the quality and perhaps  quantity
of leakage, and  the direction and rate of movement  of  the contaminants.   There
is no set  number of  wells which  should  be  required  around  a  facility.   If the
facility is a  pond or  lagoon  with  a  shallow  water  table it is  likely  that the
leakage could  be detected with one well.

In over-simplistic  terms, the shallow  ground  water table  is often a  subdued
replica of the surface  topography, and  normally, shallow monitor wells  can  be
properly placed  using  a  site  topographic  map.   Following this concept, many
early wells were installed at the lower surface elevation at  a  facility.  This
concept was widely used in the late 1970's  and early 1980's when monitor wells
were  first being installed  throughout  the  country.   History  indicated that
this  logic was right in over 90 percent of  the cases as  verified by construct-
ing water  table  maps after the wells were installed.  Another concern  that has
been  "voiced"  is the placement of the  well  screen.   Recent  guidance  has sug-
gested that screen lengths should be small  in order to measure  discrete inter-
vals  and  that long  screen  intervals  would dilute  discrete plumes.   The vast
majority of  monitor  wells that  were  installed without  benefit of subsurface
control and  with varying  screen lengths functioned as  they  were planned, and
most old facilities were  demonstrated to have leaked.

Where  the  primary purpose of monitor  wells  is  to  determine  the extent  of
contamination  migration,  additional monitor wells are usually required.   These
monitor wells  are generally placed at  further distances from  the  source both
in the horizontal and vertical plane.

Ideally,  leachate from  a landfill  or  leakage from  a  lagoon moves  downward
until  it   intersects the  water table.   Movement and  dispersion is then con-
trolled by gradient, sediment-waste  reactions, quantity of the waste,  and  the
hydrogeology  of  the  area.  At existing  sites  where  little is  known about  the
underlying  sediments or  direction  of  ground water  movement, several  wells
should be  installed  around  each  potential  source.   Selected  wells  may also  be
completed  at  different depths.   Figure 3-15 is a  hypothetical cross section
indicating  potential  migration  paths  and  indicates the  need  for  detailed
information prior to monitor well placement.
                                     3-44

-------
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3.2.3.2  Screen Placement
The screened  interval  for a monitor well  should  be  placed to monitor a  dis-
crete interval of  the  water  bearing  information or a  segregated  water  bearing
unit  that  has minimal  interaction  with  other units.   Admittedly these  are
ideal conditions  that  do not  always exist,  although  the placement of  seals,
both  upper  and lower,  have  been used  effectively  to segregate the  screened
unit.

Determination of the proper screen placement  is dependent on site hydrogeology
and the  physical  characteristics  of  the parameters being monitored for.   One
concern  is  over  the proper  placement of  well  screens when sampling is  to be
conducted for  chemical constituents  that  are  lighter than water.  In  uncon-
fined formations the screen  must  be  placed to  extend  from a few feet  above to
a few  feet  below  the range of  seasonal fluctuation anticipated  for the  water
table.   Under  confined to semi-confined conditions the  screen  must extend to
above the top  of  the formation so that water  quality analyses  will be  repre-
sentative of the  light fraction constituents present at  the  top of the  water
bearing formation.  In many contamination studies, cluster wells are frequent-
ly installed to insure  the screen(s) are  properly placed to detect a  contami-
nant  (Figure 3-16).

3.2.3.3  Installation Methods
The choice of  drilling  method  for installing monitor  wells is contingent upon
a number of  factors including depth, sediment type,  well  construcion  materi-
als,  preferred water  sampling  methods,  and others.   As  previously discussed,
the most commonly  used drilling methods are hollow-stem auger, mud rotary, air
rotary, and cable  tool.

The most prevalent method of  installing wells without drilling  fluids  is the
hollow-stem continuous-flight auger method.  The augers allow determination of
depth to  initial   saturated  zone  and does not introduce  drilling  fluids into
the borehole.   This drilling method may,  however, allow fluids  from  an upper
zone  to  come  in   contact with those of  a lower zone.   Generally the  auger
method is restricted to depths of less  than 150 feet.
                                     3-46

-------
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                  3-47

-------
Hollow-stem augers  come  in several  sizes with perhaps the most  useful  having
8-inch  and  10-3/4  inch  outer  diameters (OD).   The  inner diameters of  these
hollow  stems  are  3-3/8  inch  and  6-inch,  repsectively.  Both  2-inch and  4-inch
monitor wells are commonly installed with these augers.

To  install  a monitor  well  using  the  hollow-stem  augers,   the  borehole  is
drilled and the sediments sampled continuously or at  intervals of 3 to  10 feet
depending on  the  degree  of subsurface data  needed.   The  borehole  is  advanced
until the  desired monitoring zone  is  reached.   With the augers still  in the
borehole, a water sample  can be  collected  for  preliminary assessment  of water
quality by inserting a bailer through the hollow stem of  the  auger.

The  well  casing and  screen  can  either be lowered through  the augers  or in-
stalled after the augers  are pulled  from  the hole.   Generally, if the sedi-
ments are  unconsolidated, there is  a  tendency for  the  walls of the hole  to
collapse as the augers  are removed.   For this reason, the casing is installed
through  the   hollow  stem  of  the augers  before removing  them from the  hole.
Under these conditions, however, it  is difficult  to  place the gravel  pack and
to ensure a bentonite  seal in  the  annul us.   If the sediments will  remain open
after the augers  are removed,  then  the casing  and screen can be assembled and
inserted in the borehole  after removal  of  the  augers.  A gravel  pack  can then
be installed  and the annulus sealed with bentonite or cement  grout  back  to the
surface.

In recent years,  the hollow-stem auger has  been  highly  touted  as  a preferred
installation  technique  because additional  fluids are not  introduced  into the
ground  water  and  because  representative  samples  are  more  easily  collected and
interpreted.  Although for shallow,  water  table  aquifers  this may  be  the best
method, there are limitations  to the  method.  One of the most  severe  limita-
tions is the  possible migration of contaminants  down the annulus  if  the well
is completed  in  a   deeper horizon  than the lowest   contaminated  zone.   For
multi-layered  systems,  the deeper  zones should  probably be  drilled with mud
rotary  or with a surface  casing set through the contaminated  zone.

In cases  where the  water table is  deep and  the sediments   are competent  to
moderately competent,  air rotary methods  may  be used.    Like the  auger tech-
                                     3-48

-------
nique, this method has the advantage of introducing no liquids into the forma-
tion.   It  has the disadvantage that wells cannot  be  completed  very  far below
the water table  because  the  hole will  not  remain  open when air circulation is
stopped.  In  hard  rock  areas,  air  rotary  drilling can be conducted well below
the water table  and has several advantages over other methods (see Table 3-3).

In  many  instances,  effective  stratigraphic  sampling  and well  installation
requires  the use  of drilling  fluids.   Unfortunately, circulating  drilling
fluids  tend  to   invade the permeable zones.   This lost fluid may  impair well
performance  and/or complicate  interpretation  of   chemical  analyses  from  the
monitor well.

Since the  exact amount  of fluid loss  may  not  be  known, the  amount  of subse-
quent pumpage required to remove all drilling water prior to obtaining a valid
sample  of  in situ formation water may  be difficult  to determine.   Tracers
placed  in  the drilling  fluid  may  help to indicate when all  introduced fluid
has  been  removed.   One example of a  tracer is  lithium  bromide.    In  a test
using this  tracer, over  five  times as  much  fluid was produced  as  was lost
before all of the  tracer was recovered, due to mixing of insitu and introduced
fluids.

The primary  advantage of the mud rotary method is that hole stability allows
removal of drill pipe and installation of casing large enough to accommodate a
submersible  pump.   Prior to removing  the  drill pipe, a clean  up  trip of the
borehole  is   made  by running  the  drill  bit from the  surface to  the total
depth.  Generally the  borehole is flushed with potable water to thin out the
drilling fluids  and to facilitate the installation of the casing.

In mud rotary drilling, potential crossflow between formations  is difficult to
detect  prior to completion.    In fact, recognizing water-saturated formations
at all  may  be difficult.  As  a  result,  gravel  packs may  be  installed at the
wrong  elevations, allowing  crossflow between  layers  or  migration  down  the
annulus from masses of perched water above the water table.

Figure 3-17  indicates an example of a mud-rotary installation where it was not
know  that  a  thin zone of contaminated water was  perched on a thin clay above
                                     3-49

-------
  100
  200
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  400
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  500
                                   Generalized
                                   Stratigraphy
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 380' to 520'
 6 5/8" dla.
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                           and

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                                                                      Water
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                                                                          (Red Bed)
                      Figure 3- 17.   Completion of a  Monitor  Well
                                      Using Mud Rotary Drilling
                                            3-50

-------
the  regional  water table.   The  clay zone was  not  discovered in cuttings  or
undisturbed  sediment  samples.   The gravel  pack extended  above the  screen,
which  is  normally  done  to ensure sampling the top of the  zone of  saturation.
In this  case,  however,  the gravel  pack location allowed the  perched  water  to
migrate down the annulus.

These  conditions are  somewhat  analogous to a multi-layered  aquifer.   Here,  if
only one  or  two casing  volumes are bailer or pumped, the  samples may seem  to
indicate  that  the  lower  zone is contaminated.   Figure 3-18 illustrates the
concentration  versus  volume  pumped  for such  a well and  demonstrates  that,  in
this case,  the lower aquifer  was  not  contaminated.   Other instances  of  mis-
leading monitor well data are common.

Collection of  multiple  samples as  shown in Figure 3-18  can be a valuable aid
in explaining  anomalous data.  This data,  combined  with  the completion records
of the well shown  in Figure 3-15, gave  the first indication that  contamination
had traveled as deep as the perched layer, but  no further.

Once the  drilling  method has  been  chosen and  the borehole drilled,  the  well
casing and  screen  are lowered into the borehole.  Figure  3-19 shows  the  con-
struction  of   a  typical  shallow monitor  well.    The monitor well  screen  is
surrounded  by  a   gravel  pack generally  consisting  of  a  graded  sand  which
matches  the  screen slot  size.  The gravel  pack usually  extends  a  few  feet
above  the  screened interval  in order to prevent the overlying annular bento-
nite seal  from being drawn  into the gravel  pack during puming  or  bailing  of
the well.

The  annulus  is  sealed  with  a bentonite  plug  consisting  of  2  to  5  feet  of
granular  or  pelletized  bentonite.   The seal  prevents the  migration of fluids
from overlying zones  from entering  the monitoring zones through the  borehole
annulus.   This  seal  is  most effective when  located  opposite   the  overyling
confining zone or  aquitard.

The  remaining  borehole  is grouted  back to the  surface  with grout,  bentonite,
or a combination  of both.  The grout  is  best pumped through  a  small  diameter
pipe  inserted   into  the  annulus and  placed  a  few feet  above   the  bentonite
                                     3-51

-------
  Z.3 -

  2.2 -

  2.1 -

  2.0 -

  1.9 -

  1.8 -

  1.7 —

  1-81—

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a 1.4
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o
  0.8

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  0.4

  0.3

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PUOID si ซrt•fl-
  0.0
   10/80
                11/90
                           12/80
                                        1/81
                                         Dlyi
                                               1/21/61
                  1/22/81
                 Hour*
                                                                  1/23/81
             Figure 3-18.   Manganese Concentrations vs.  Time
                             of Pumping-Data  From Well  Shown
                             in Figure 3-15
                                     3-5;

-------

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	 Screen

Natural material
 or gravel pack
  (as required)
           Figure 3-19.   Monitor Well Installation Diagram
                                 3-53

-------
seal.  However,  grout  can  be  poured  from  the  surface  but the placement should
be verified with a trimie pipe.

A concrete well  pad  should  be  placed  around the  well  which will  direct runoff
away for  the well.   For  ease in sampling and  to minimize  the  potential  for
mixing of waters between wells, each monitor well can  be supplied with its  own
(i.e., a  "dedicated")  bailer  or pump.  In some  instances,  a barrier  post  may
be  installed  with the monitor  well.   This post  serves the dual function  of
protecting  the  monitor well  from off-road machinery  and  securing  the  well
against tampering.   All  locks at a given facility can  be  keyed  alike to  pre-
vent subsequent complications (Figure 3-20).

3.2.3.4  Materials of Construction
There  are numerous  factors to  consider  when selecting  the materials for  a
monitor well.    In the past,  steel  or plastic  materials have  been  utilized
because they  are readily available  off  the  shelf.   Because costs  associated
with  well  installation  and materials  are often  insignificantly  small  with
respect to  the  long term  costs  associated  with  sampling  and  analysis,  it  is
important to place  greater  emphasis  on the proper selection of well construc-
tion materials.

It  is  often practical to  compromise  between  cost and  ideal construction  ma-
terials because the  effective  life expectancy  of  a  monitor  well  is  as  yet
unknown and highly  dependent on  the  levels and types  of ground water contami-
nants.  Furthermore,  a consideration of  site specific  contaminants may indi-
cate that  less  expensive  materials  will  enable  reliable  collection of ground
water  samples  for  selective  parameters.   Table  3-6  list  the  advantages  and
disadvantages  of  the  major types  of materials available  for monitor  well
construction.

Most liquid  wastes are corrosive, and many environments,  both subsurface  and
surface, are also corrosive.  In the Gulf Coast area,  many steel monitor wells
have deteriorated  on the surface to  the  point  that  caps  and  fittings may be
corroded  in  place.    In   the   Gulf  Coast area,  shallow  sands   (+20  feet)
frequently  contain  saline  water, especially  if the land  surface elevation is
below 15 feet.   In these areas,  steel casing and  screens deteriorate rapidly.
                                     3-54

-------
 1) SINGLE CASED WELL
 ^  "
U-
3'X3'X6' CONCRETE PAD
     APPROX 2'
                                 6" SQUARE PROTECTIVE POST
                                      WITH LOCKING CAP
                   ป 4 ซ
                   , ป ป
                   fc 4 4
        4' PVC WELL CASING WITH SLIP
           .-	CAP AND HANDLE
       ป
1      LV/-
                                                              APPROX. 3'
                                                            "
                                        CEMENT/BENTONITE GROUT
                                         8' BOREHOLE
 2) DOUBLE CASED WELL
 3'X3'X6' CONCRETE PAD
 12" BOREHOLE	'


CEMENT/BENTONITE
     GROUT
                                      4" WELL CASING WITH
                                       SLIP CAP AND HANDLE
            6' PROTECTIVE POST
            WELDED TO 8* STEEL
              SURFACE CASING
                                        APPROX. 3'
              Figure  3-20. Monitor Hell Surface Completion
                                3-55

-------
                                                        TABLE  3-6
                                            WELL CASING AND SCREEN MATERIALS
     TYPE
                                       ADVANTAGES
                                                    DISADVANTAGES
PVC (Polyvinyl-
chlori de)
L i ghtwe i ght

Excellent chemical resistance to weak
alkalies, alcohols, aliphatic hydrocarbons
and oils

Good chemical resistance to strong
minerals acids, concentrated oxidizing
acids, and strong alkalies
Weaker, less rigid, and more temperature
sensitive than metallic materials

May adsorb some constituents from
ground water

May react with and leach some
constituents from ground water
                   Read i Iy  ava i IabIe
                                                Poor  chemical  resistance to ketones,
                                                esters,  and aromatic hydrocarbons
PoIypropyIene
TefIon
Low priced compared to stainless steel
and TefIon

L ightwe ight

Excellent chemical resistance to mineral
aci ds

Good to excellent chemical  resistance to
alkalies, alcohols, ketones, and esters

Good chemical resistance to oils

Fair chemical resistance to concentrated
oxidizing acids aliphatic hydrocarbons,
and aromatic hydrocarbons

Low priced compared to stainless steel
and tefIon

L ightweight

High impact strength
                   Outstanding  resistance  to chemical
                   attack;  insoluble  in  alI organics except a
                   few  exotic  fluorinated  solvents
Weaker, less rigid, and more temperature
sensitive than metallic materials

May react with and leach some
constituents into ground water

Poor machinabi I ity - it cannot be
slotted because it melts rather than cuts
Tensile strength and wear resistance  low
compared to other engineering plastics

Slots may compress with time.

Expensive relative to other plastics  and
stainless steel

Difficult to install and keep it straight
in the hole
                                                      3-56

-------
                                                        TABLE 3-6
                                       WELL CASING AND SCREEN MATERIALS (Continued)
     TYPE
                   ADVANTAGES
       DISADVANTAGES
Kynar
Mild steel
Stainless steel
Greater strength and water resistance
than TefIon

Resistant to most chemicals and solvents

Lower priced than Teflon

Strong, rigid; temperature sensitivity not
a problem

Read!Iy aval I able

Low priced relative to stainless steel and
TefIon

High strength at a great range of
temperatures

Excellent resistance to corrosion and
ox i dat ion

Readi Iy ava i I able

Moderate price for casing
•  Not readily available

•  Poor chemical  resistance to ketones,
   acetone
•  Heavier than plastics

•  May react with and leach some
   constituents into ground water

0  Not as chemically resistant as
   stainless steel

•  Heavier than plastics

ซ  May corrode and leach some chromium
   in highly acidic waters

•  May react as a catalyst in some organic
   reactions

•  Screens are higher priced than plastic
   screens
Adapted from Manufacterer's  Literature  Provided  by  Johnson Screens, Material Selection  for Ground  Water
Mon itor i ng Wei I s
                                                      3-57

-------
In most  ground water investigations, PVC  materials  can be utilized.   PVC  is
resistant to most chemicals except aromatic organics such  as  ketones,  esters,
etc.    However,  the  concentration of  contamination will normally  be  small  and
should  have no  significant  effect on  the integrity  of  the  casing.    Where
adsorption  of  contaminants on  the PVC  casing is  of  concern,  a more  inert
material, e.g., stainless steel  or teflon,  can be  used.

The  most significant  problem to  be solved  with selection  of materials  of
construction is  possible sample contamination.   The  use  of PVC  glue  to weld
casings  to  screens  can  result in sample contamination.  Figure  3-21 is a gas
chromatograph  scan  of a  sample  of water  collected  from  a monitor well  con-
structed with  PVC pipe  and glue.  Figure  3-22 is a scan of  PVC  glue  in dis-
tilled water.   Later gas chromotography/mass  spectroscopy  analysis  identified
some of  these  peaks  as methylethyl ketone,  toluene,  and tetrahydrofuran.  PVC
could still be utilized in this investigation by using  threaded coupling.

In addition to pipe  and casing materials, the gravel  pack  and  grouting  materi-
als  should  be selected  to minimize  sample  contamination.   Gravel pack sand
should contain  no chemical  additives.   Bentonite pellets,  which  are  normally
used  in  sealing  the producing zone have been  mixed with distilled  water, and
TOC  values  in  excess of  6,000  mg/L  have been found.   In  addition,  bentonite
supplied by  typical  drilling  mud suppliers may contain some  organic  polymers
in order to meet American Petroleum Institute standards for drilling fluids.

3.2.3.5  Well Development Methods
All  drilling methods alter the  formation hydraulic  properties in the  vicinity
of the  wellbore, although  to  differing  degrees  depending  on  the  formation
materials.   These   well bore  damage  effects  are  greatest in  unconsolidated
sediments where development techniques are  required in order to achieve repre-
sentative ground  water  results  from the wells.   Well  development  serves the
following purposes:

          -  Remove  the  filter cake  (drilling  fluid film that develops on the
             borehole wall) and enable water to flow easily into the well.
          -  Remove  any   solids  or  liquids  that  have invaded  the  formation
             during  drilling.

                                     3-58

-------
Figure 3-21.
G. C. Scan Water Sample from Monitor Well
Constructed with PVC Pipe and Glue
                        3-59

-------
Figure 3-22.   G.  C.  Scan - PVC Pipe and Glue in
              Distilled Water
                       3-60

-------
          -  Remove  the finer  particles  and  create a  graded particle  zone
             around  the well which  increases the porosity  and  permeability  of
             the formation  near  the well  and reduces the  production of  fine-
             grained material by the well.

A  few  of the  development  methods  used  in the  water well  industry have  been
adapted  for use  in  developing  monitor  wells  because  they  cause the  least
detrimental effects  to the subsequent ground  water  data  collected.

Ba i1i ng
A hollow cylinder of smaller diameter than the  well  and  with  a trap bottom  to
prevent  water  from  flowing  back into the well  is  used  to repeatedly  remove
water  from  the well.   This  method  is commonly used for developing 4-inch  or
larger  wells  when  a drilling  rig  or other hydraulic  hoisting equipment  is
available to perform the bailing process  and create  a high velocity flow into
the well.   False bailing  is  especially  useful  in  developing wells.   In  this
method,  a "full" bailer  is  hoisted  to above  the water  level  and then  "dropped
back"  into  the well.   This  creates a surge  at the  screen/formation zone and
assists with removing fines.

Pumping
Submersible  pumps   are  commonly used  to develop  4-inch  monitor  wells  with
surging  as  a complimentary technique.   Many 2-inch wells have  been  success-
fully  developed using jet  pumps  which can develop  high  velocity flow into the
well.  With the exception of 2-inch submersible pumps (which  are expensive and
inefficient  in pumping sediment particles), most  other pumps  (i.e.,  bladder
pumps,  peristaltic  pumps)  fitting   2-inch wells  do  not  develop  adequate  flow
velocities to develop monitor wells.

Surging
Surging  is  a  technique used  in conjunction  with  other  methods   to  develop
monitor  wells  and  prevent  the filter pack material  from bridging  as  a result
of  one directional   flow.   Bridging may  result  in  future  well  flow  problems
requiring  redevelopment or  premature  replacement  of  the  well.    Surging  is
performed in  several manners including false  bailing  or  plunging  the  bailer
without  removing  it  from  the  well, raising and  lowering  a  submersible  pump
                                     3-61

-------
while pumping,  allowing developed water to  surge back  into  the  well,  (prefer-
ably without actually removing the water from the  well  casing)  or with the use
of a surge block.

Water Jetting
Water  jetting   is  a  practice  often used  to break up  the  filter cake on  the
borehole wall  and  also to backwash the filter pack through  the  screen.   This
can  be  a  very  important  development  technique  when  drilling   additives  are
required to keep the borehole open during drilling.   This method can result in
drilling fluids being  forced  into the  formation and  therefore  it must be used
in conjunction with  extensive evacuation  type development to ensure  that all
drilling fluids are withdrawn from the formation.

Air Development
Monitor  wells   can  be  developed  using  air  compressors  with an  eductor  type
system  which  enables  water  to flow out  of the well  along with the  flow of
air.   This method  is  not often recommended for developing  monitor wells be-
cause it can result  in air being  forced  into the  formation.  The often power-
ful  surges  of   water ejected  from  the  well  may create containment  as  well  as
health and  safety  problems if the  ground  water is  heavily  contaminated.   Used
with proper safeguards, air is an effective development tool.

Measuring Development
The  sensitive  nature  of water quality analyses from monitor wells  has caused
an  increased  concern  over development practices.   As  a result, a number of
parameters are  regularly used to measure the adequacy of monitor well develop-
ment.  These parameters include turbidity, pH, and conductivity.

Turbidity is a commonly  used  indicator of well development  although it is not
the best.   Reducing  the  turbidity  does not necessarily mean that the wellbore
area of  influence is  adequately developed  to  provide  representative samples.
On the  other  hand  turbidity  may  cause greater unreliability in sampling for
certain  parameters (i.e., metals)  and therefore may  be an indicator  of the
need for additional development when monitoring for these parameters.
                                     3-62

-------
The pH of  the  ground  water  is  often  affected  by  drilling practices and can be
used to determine when  the  affected  fluids  have  been  removed.   This parameter
is also useful  in  determining  if the bentonite  seal  thickness  is  adequate to
prevent grout  contamination of the  filter  pack  which,  if containing  cement,
would increase the pH and possibly affect water quality analyses.

The conductivity of the ground  water is  another parameter used  for  determining
when the well has been developed sufficiently  to  provide water  quality samples
that are representative of the  aquifer.   As the well  is developed,  the conduc-
tivity should stabilize.

3.2.4  Lysimeters
Lysimeters  have  been used with  some  success  in obtaining water samples  from
both saturated and unsaturated  sediments.   In  most ground water contamination
investigations, monitor wells are better  suited  for sampling or monitoring in
the saturated zone.   In the unsaturated  zone,  the normal monitor well will not
collect sufficient fluid.   Lysimeters are frequently  able to  detect leachate
or  surface infiltration in the  unsaturated  zone,  and  can be  used  in  a  leak
detection  system to sample soil-pore water.

The  most   commonly used lysimeters,  suction  lysimeters, are  of  two  general
types,  vacuum  and  pressure-vacuum   lysimeters.   Vacuum lysimeters  utilize
vacuum only and  are   limited to approximately  15 feet  in depth  (over 15 feet,
the  pressure type  is recommended).   Pressure-vacuum  lysimeters  can  be in-
stalled to a  depth of approximately  50  feet.   Below  50 feet,  a modified pres-
sure-vacuum lysimeter  can  be   utilized.    Figures  3-23, 3-24,  and  3-25 are
schematic  drawings  of  each general  type.   Pan  lysimeters  are also  briefly
discussed.

3.2.4.1  Installation and Operation of Suction Lysimeters
Generally,  lysimeters should be installed prior to construction of the  land-
fill, pond, lagoon,   or  landfarm  operation.   In this  way, background samples
can be obtained prior to operation.  Holes are drilled to the desired depth by
using a hollow-stem  auger or hand auger.   The hole should then be cleaned as
well  as  possible.    In order  to  provide an  appropriate medium to move  soil
moisture under  capillary pressure, the  porous  cup  should be  in contact  with
                                     3-63

-------
MALE  CONNECTOR
PVC  CEMENT
                                                                VACUUM  DISCHARGE  LINE
                                                                  TO  THE  SURFACE
                                                                PVC  CAP
                                                                 PVC  PIPE
                                                                 1/4"  POLYETHYLENE
                                                                  TUBING

                                                                 PVC  CEMENT


                                                                 POROUS  CUP
                     Figure  3-23.   Lysimeter  Vacumm
                                  3-64

-------
MALE  CONNECTORS
EPOXY  CEMENT
1/4"  POLYETHYLENE  TUBING
 (DISCHARGE  LINE) 	
                                                              TUBING   TO   THE  SURFACE
PVC  CAP

1/4"  POLYETHYLENE
  VACUUM-PRESSURE  LINE
                                                              PVC  PIPE
                                                              PVC  CEMENT
                                                              POROUS  CUP
                    Figure  3-24.   Pressure-vacuum Lysimeter
                                        3-65

-------
 PVC  CEMENT
 POLYETHYLENE  TUBING
 BRANCH  "T"
 CONNECTORS
POROUS  CUP
                                                                  TUBING  TO  SURFACE
                                                                  MALE   CONNECTORS
PVC   PIPE  CAP
                                                                  PVC  PIPE
                                                                  FEMALE  ELBOW
                                                                  POPPET  CHECK  VALVE
                                                                  EPOXY  CEMENT
                                                                  POLYETHYLENE  TUBING
            Figure  3-25.   Modified  Pressure-vacuum Lysimeter




                                        3-66

-------
material  that is  as  fine as,  or  finer grained  than,  the native  sediments.
Several  commercial  products  are available  including  Super Sil and  Novacite,
both of  which are relatively  inert.   Table 3-7 gives a  leachate  analysis  of
Grade  100-C  Novacite  (finer  than  200 mesh  silica  powder)  and  Table  3-8
contains physical and chemical data on Novacite.

Many existing  lysimeters  have  been  installed by the  following  method  and have
subsequently  produced  samples  of sufficient quantity for  sampling.   Approxi-
mately six  inches of  Novacite  is placed  in  the  bottom of an augered  hole (See
Figure  3-26 and  3-27).   The  lysimeter tip  assembly  is then lowered  into  the
hole, and Novacite is added until the lysimeter cup is covered  by  approximate-
ly six  inches.   Native soil, which was removed from  the  borehole,  is used  to
backfill the  hole for  approximately  two  feet and  then three feet  of  bentom'te
(pellets,  granular,  or  powder) is  added  to  prevent  infiltration  down  the
borehole,   the rest of the hole is  then filled  with native material up to 2 to
3 feet below ground surface where another bentonite seal  is installed.

Another alternative for lysimeter installation  (shown in Figure 3-28)  involves
digging  a narrow trench,  about 2   to  3 feet deep,  from the  location  of  the
control  box to  the  point where the  lysimeter  tip assembly will  be  located.
From the  intersection of  the  end wall  of the trench  and its bottom,  a hole is
then dug with a  hand auger or post  hole digger.   This hole is generally 2 to 3
feet deep,  and  angled downward  from and extending away  from  the end  of  the
trench.

Novacite  or a  Novacite  and  water  slurry  is  placed  in  the  far  end  of  the
augered hole.   The porous cup  of the  lysimeter tip assembly  is placed on  the
Novacite  at a depth  of approximately  5.5 feet  below  the  ground surface.   Dry
Novacite  or Novacite slurry  is then  placed in  the hole to cover  the tip  and
about  12  inches  of  the  lysimeter  tube.    A  3-  to  6-inch plug  of  bentonite
pellets is  placed  over the lysimeter  and Novacite.   Because  the  augered hole
is at an  angle,  the  bentonite  will  not be directly above, and therefore would
not  obstruct surface  water  percolation through,  the soil which  immediately
overlies  to the  lysimeter tip assembly.  The tubing  bundle is then connected
to the existing  tubing in the trench and the trench backfilled to  the surface.
                                     3-67

-------
                     TABLE  3-7

        Leachate Analysis of /200 Novacite
Metal
Ag
As
Ba
Cd
Cr
Hg
Pb
Se
Units
ppb
ppb
ppb
ppb
ppb
ppb
ppb
ppb
1-A
<3.0
<2.0
61
<1.0
<5.0
<1.0
<10.0
<5.0
1-B
<3.0
<2.0
104
<1.0
5.9
<1.0
<10.0
<5.0
1-C
<3.0
<2.0
89
<1.0
<5.0
<1.0
<1CLO
<5.0
                     TABLE  3-8
      Physical and Chemical Data on Novacite
           Typical Chemical Composition



Si02                                         99.12%


Fe203                                         0.04%


Ti02                                         0.015%


CaO                                            0.0%


MgO                                            0.0%


A1203                                          0.61




True specific gravity at 70ฐF,  2.650


pH in distilled wter 6.0 to 6.3.
                       3-68

-------
                                                      Vacuum Gauge




                                                      Vacuum-pressure Line (Black)







                                                      Discharge Line (Clear)




                                                      Sample  Bottle
      SOIL  BACKFILLED  TRENCH
                       SOIL  BACKFILL
                 VACUUM  PRESSURE  LINE
 0'-




V p.'
                       8ENTONITE  SEAL
                       SOIL  BACKFILL
                       NOVACITE
-• o-
.3; .
'•p''.
'ฃ>.
•k^





                 DISCHARGE  LINE
Figure 3-26.   Sampling  and Installation of  Pressure-vacuum Lysimeters
                                     3-69

-------
                                                 Vacuum Gauge



                                                 Vacuum-pressure Line  (Black)






                                                 Discharge Line (Clear)



                                                 Sample Bottle
             ,     .o. -      >
           ••n   • •ซ• O. •'ซ"*••'••.*>•• o-
           t>-ฐ \^ฐ.:  •  ~ -o.--.' ซ>.• -o •••:
 SOIL  BACKFILL  IRECOMPACTEDl
               NOVACITE
Figure  3-27-  Sampling and  Installation  of Vacuum Lysimeters




                               3-70

-------
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                                                                       CD
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                                                                       01
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-------
Other options are available for the completion of the hole  after  the lysimeter
is installed.   These include the sole use of native materials and  the  use  of
varying amounts and  combinations of crushed silica-sand and  bentonite and  are
largely dictated  by the type of soil  concerned  and the tools available.   As
long  as  the  primary  objective  of creating  a  thorough contact between  the
porous ceramic  cup  of  the  sampler  and  the  soil  in the borehole  is achieved,
varying alternatives can be  utilized.   In most types of installations,  the
vacuum and/or  pressure-vacuum and  discharge  lines are buried in  a  trench  and
routed outside the  pond, landfarm,  or  landfill area to a central  location  for
sampling (see Figure 3-26 and 3-27).

Soil-pore water  (soil  moisture)  is stored  in the  small capillary  spaces  be-
tween soil  particles and on the surfaces of  the soil particles.   In unsatu-
rated soil,  moisture is held at pressures  below atmospheric pressure  (under
suction).   To  remove  this moisture,  a  negative  pressure  (vacuum) must  be
developed in  order  to pull  the moisture from the soil  particles.   The  amount
of vacuum required  to remove this   soil moisture  is the soil  suction.   In  wet
soils the  soil suction  is  low,  and the soil  moisture can  be removed  fairly
easily.  In dry soils, the  soil  suction is  high,  and it is  difficult to  remove
the soil moisture.

Vacuum is applied to lysimeters by means of  a pump.   Either a hand operated or
electrical  vacuum  pump can be used.   For field  work, a hand pump  is desira-
ble.  Figure 3-27 is a typical set-up for a  vacuum system.   A vacuum is  placed
on the system and  valve "A" is closed.  This  vacuum  should  be maintained  for
at least eight hours (if the lysimeter integrity has been  breeched,  the  lysim-
eter  may  lose  its  vacuum  in a  significantly  shorter time, usually  within
minutes).   If soil  moisture or leachate is present,  liquid  will  be collected
in the flask.  After the vacuum  is applied  and the valve  closed, the pump  can
be removed  and used  to sample other lysimeters.   For permanent  pump installa-
tions, more elaborate automatic sampling equipment can be  utilized.

Figure 3-28 is an example of one alternative for a more permanent installation
set-up for a pressure-vacuum lysimeter.  The system is equipped  with a monitor
box which provides  a permanent,  continuous means of observing the behavior of
the  lysimeter.   The vacuum pressure  and discharge lines  from  the lysimeter
                                     3-72

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each enter  the box through a  bulkhead  union  located  at  the base of  the  box.
The black colored,  vacuum-pressure  line is connected to valve  "B"  mounted  on
the right  side of  the  panel  board, and penetrates  the  board  just above  the
valve.    The  clear  discharge  line  is  connected to  the  tubulature of  250-ml
sample  flask  by a  short  piece of neoprene tubing.   The discharge line  then
passes through  a flask  stopper and  is  connected  to  a tee fitting.   One branch
of the tee  is  attached  directly to  the vacuum gauge,  and the second branch is
connected to  the  "A"  valve  by a  short  length of  polyethlene  tubing.   The
discharge line then penetrates the panel above the "A" valve.

The valves  used in  the system  provide  a  fast, sure  means of access  to  the
vacuum-pressure and discharge  lines to  apply  a  vacuum or evacuate  fluid.   The
vacuum gauge  allows continuous  visual  monitoring  of the system.   All  compo-
nents  are  housed  in a  weather resistant  box.  A plexiglass front  panel  pro-
vides visibility and weather resistance.

A  similar   installation  set-up can  be  utilized  in the  case of the  modified
pressure-vacuum  lysimeter, which  is  useful   in  monitoring  soils  at  depths
greater than  50 feet.   However, the internal  sampling procedure for this  type
of lysimeter  is slightly different,  in that a separate upper chamber for water
storage  is  utilized.   Two  check  valves  permit  the flow  of  water  from  the
porous cup  into the  upper  chamber when a  vacuum is  applied.  When  pressure is
subsequently  applied, the  collected sample  is removed  from  the chamber to the
surface.  This  procedure  prevents the  high pressure (necessary to  bring water
to the  surface)  from reaching the porous  ceramic cup chamber,  where  it would
force much  of the collected water back into the soil.

3.2.4.2  Installation and  Operation of Pan Lysimeters
Pan lysimeters  (free drainage  type  lysimeters)  can  be constructed  and used to
sample  macropore  or  fracture flow.   They can  be  used  in conjunction  with
suction  lysimeters.   A pan  lysimeter can be  constructed  of  any  non-porous
material  (e.g.,  sheet  metal,  glass brick) which  will  not  interact  with  the
leachate, possibly jeopardizing  the validity of the sampling effort.

The operating  principle of a  pan lysimeter is  simple.   Water  draining freely
through the soil macropores will collect  in the soil  just above the pan cavi-
                                     3-73

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ty.   When  the  tension in  the  collecting water  reaches  zero, dripping  will
initiate and the pan will funnel the leachate into a sampling bottle.   The use
of a  tension plate  or a fine  sand packing reduces  the  extent of  capillary
perching at  the cavity face and  promotes  free  water flow into the  pan  (EPA,
1986).

3.2.4.3  Other  Information on Lysimeters
Recent  EPA  guidance documents  which  discuss unsaturated  zone monitoring  in-
clude:

          Hazardous Waste Land Treatment (SW-846, EPA, 1983).
          Permit  Guidance Document  on  Unsaturated  Zone  Monitoring
          for Hazardous  Waste  Land  Treatment  Units  (EPA/530-SW-86-
          040,  1986).
          Permit  Guidance Manual  on  Hazardous  Waste  Land Treatment
          Demonstrations  (U.S. EPA Office of Solid Waste,  1986).
          RCRA  Guidance Document Land Treatment Units (EPA,  1983).
          Test  Methods  for Evaluating  Solid  Waste  (SW-874,  EPA,
          1986).
          Vadose  Zone  Monitoring  for Hazardous  Waste Sites  (Everett
          et al., 1983).

3.2.5  Tensiometers
Tensiometers can be used  at proposed or existing lysimeter locations to deter-
mine whether the soil  suction values of those locations are within  the operat-
ing range of the lysimeters.    Tensiometers  can  be  used at  the same locations
and depths as the proposed active area and background lysimeter tip assemblies
in order to  determine  soil suction values.

A  tensiometer  consists  of  a  porous ceramic cup,  a  fluid  reservoir, and  a
vacuum gauge.   The porous ceramic cup is designed so that  the pores in the cup
are finer than  the  pores  in the surrounding soil matrix.   This is  required so
that the water  in  the  tensiometer will  experience the same  negative pressures
as the  water in  the  soil.   The fluid reservoir  provides a  continuous liquid
medium  to transport the negative pressures  from  the  porous  cup  to the vacuum
gauge.   This liquid  is  normally  water  that has  been  deaired as  much  as is
                                     3-74

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practical and  has  had an herbicide added to inhibit algal growth  in  the  ten-
siometer.   During construction  of  the tensiometer, the  reservoir is  filled
with water  and the tensiometer  allowed to  stand  open  so that the  porous  cup
becomes  saturated.   After the porous  cup  is saturated, the reservoir  is  re-
filled,  the tensiometer  sealed  and  the porous  cup enclosed  in  plastic  to
prevent water  loss.  The plastic  is removed  prior to installation.

The installation of tensiometers  into the soil  is relatively  simple.   First, a
hole is cored  in the soil to desired depth.   The tensiometer  is then installed
into the  cored hole.    Care  should  be taken that the tensiometer  fits  snugly
into  the hole;  this   can  be  accomplished  by  using a  soil   corer  available
through the tensiometer manufacturer.

After  installation, the tensiometer is monitored simply by reading  the value
shown  on  the  face of  the  vacuum gauge.  The  gauge should be monitored  on a
schedule similar to that used  for well  testing.   A  recommended schedule is 1,
2,  4,  8,  15,  30, 60,  120, 230,  480 and 1440 minutes.   This  information  will
allow  the determination of  when  the tensiometer  has stabilized, and  what the
true value  is.  After the tensiometer  has  been  stabilized, the  value of  soil
suction  is  simply  read from  the  gauge.   If  the soil suction  value  is success-
fully  obtained by  the tensiometer,  this  value  will  represent the  negative
pressure which must  be exceeded  by a  lysimeter  in  order  to  retrieve  a sample
of  the unsaturated zone pore  water.   A tensiometer, or a lysimeter,  is  only
functional to  approximately 0.9 atmospheres  of negative pore  water  pressure.

If  a  lysimeter does  not yield  a  sample  during  several  consecutive  sampling
events, tensiometer testing can be performed at its  location.   If it is deter-
mined  that  there  is sufficient moisture and yet the lysimeter is not collect-
ing water,  the  lysimeter  may not  be  functioning properly.    It can  then be
repaired or replaced.

3.2.6  Cone Penetrometer Surveys
Cone penetrometer testing has  existed within the United States for  the last 20
years.    In  the  Netherlands,  where  the  technology was  developed,  the  cone
penetrometer has been  in use for almost 50 years.  The  original cones, common-
ly  referred  to as the  "Dutch  cone"  were mechanical  and very unsophisticated.
                                     3-75

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Significant advancements  in  micro  computer  technology in the last  5-10  years
have led  to  the development of the computerized or  "electric" cone which  has
greatly increased the tool's popularity as an in situ test method  for usage in
site investigations and geotechnical design. Its practical use as  a geophysi-
cal  logging  tool,  for determining underlying stratigraphy,  is just beginning
to be appreciated.

3.2.6.1  Description
The cone penetrometer (Figure 3-29) is a cone shaped  instrument which contains
sensitive  strain  gauges  which transmit continuous electronic measurements of
both the  resistance  of  the cone's tip to penetrating  (qc),  and the interface
friction between the  penetrated soils  and the outside  of  the cone or friction
sleeve  (f$).   The instrument  is  hydraulically  advanced  into the  soil by  the
addition of hollow steel rods, which house the  coaxial  cable  that  connects  the
cone to an on-board digital computer.   The computer first formats  the data  and
then sends it  to  an  on-board  printer  producing  a three line  trace log similar
to electric  logs used in  oil  field  exploration (Figure  3-29).    From left to
right,  the  line traces  are the friction  sleeve, tip resistance,  and then  the
friction ratio  (fr) which  is the calculated value of  qc divided  by f$.

When the cone penetrates sediments with different bearing and shear strengths,
which  are directly related  to grain  size,  sorting, etc.,  unique  line-trace
"signatures" result.  In Robertson and Campanela (1983),  and  Douglas and  Olsen
(1981), soil classification charts were developed to  directly relate the  line-
trace signatures to soil types.  (See example in Figure 3-30).   Both classifi-
cation  charts  rely  primarily on the friction ratio  (fr)  to  provide the  means
for identifying soil types.

Field  experience  with various  sites  in different geological settings  (e.g.,
unconsolidated  Gulf  Coast alluvial sediments,  over-consolidated  East Texas -
Louisiana  sediments,  glacial outwash  and  ground moraine  sediments  in  south-
eastern Illinois) has demonstrated that total reliance on these  charts  is  not
prudent.   Empirical  data,  such  as  soil  samples  from   continuously  sampled
borings  placed adjacent  to  several  cone  penetrometer tests (CRT)  locations
within  a  large  survey,  provide  a  more  reliable  means  of  "calibrating"  the
tool's  response  to  site  specific  soils.   Figure  3-31 shows the  correlations
                                     3-76

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                              3-78

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between a cone  penetrometer test and a continuously  sampled  boring  drilled  5-
feet  away.   The  borehole  was also  geophysically  logged  with a  conventional
electric logging tool.

3.2.6.2  Cone Penetrometer Log Correlation
Litho-stratigraphic  correlation  between  CRT's  are  interpreted  in  a  similar
manner to the  e-logs which have been used for over  40 years  in  oils  explora-
tion.   Figure  3-32  is an  example of a  cross section interpreted from a  cone
penetrometer survey.   Figure  3-33 is an  isopach  map  interpreted  from  the  same
cone  penetrometer  survey located in Louisiana.  A total  of 57 CRT's with  an
average depth of  55-feet were conducted  over  a  nine  day period (an  average  of
350 feet per day).   Continuous soil  sampled  were collected  and described  from
5 borings located  adjacent to 5 CRT locations  for calibration.   In addition,
soil  samples were selected and tested for grain size  (sieve  and hydrometer)  to
directly correlate  the soil  classifications  to  tool  responses.   (Note:  The
soil  types  identified in the  figures have been  described using  the Wentworth
classification  system.)

The cone penetrometer can  be  a useful  tool  for  delineating  subtle  variations
in  lithologies  with  high  levels of  confidence.    Its many  advantages include
its speed as  compared with conventional  drilling  methods,  its  costs, and the
level of accuracy it can provide when the data  are  interpreted  by  an experi-
enced professional.   Some  of   its disadvantages  lie  in the  fact  that  the  tool
has limited  use in unindurated sediments (clays,  silts,  sands,  some  gravels)
only;  it  cannot  penetrate through  fissle  shales,  thick  lignites  or  coals,
sandstones,  or  carbonates.  The total penetration depth of the tool  is limited
by  the underlying lithologies.  Thick  dense  sands cannot be fully  penetrated
nor thick low  plasticity clays.   A  200-foot  penetrating  depth is the maximum
depth  to  be expected in ideal geologic  settings  such  as deltas in  southern
Louisiana.    In  the  Gulf  Coastal  sediments,  the  depth of  penetration generally
averages between 30  to 125 feet, depending on site  specific  conditions.

3.2.6.3  Other  Uses
Cone  penetrometer  surveys  can be used for several  purposes  including  standard
penetration  test  (SPT),  cyclic stress  ratios,  shears modulus  data, undrained
strengths (suu)  of clays (bearing  capacity), and  foundation  or  liner design.
                                     3-80

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More recent  advancements  in  the  technology  have  been  significantly influenced
by  the  ground  water (contamination) assessment  related industry.   Some  of
these are listed and briefly described below:

          •  Piezo-Cone -  measures  soil  pore pressure response; can
             be  used to obtain  ambient  pore  pressures  which can  be
             related to hydraulic conductivity
          •  Resistivity  (or  conductivity)  Cone  - measures electri-
             cal resistance  (or  conductance) of soil; can be used  to
             trace  contaminant  plumes of a  resistant or conductive
             nature  (e.g., metals, brine salts)
          •  Thermal  Cone -  measures  soil  thermal response  to me-
             chanical penetration;  can  be  used to determine ambient
             in-situ soil temperatures
          •  Seismic cone  -  measures soil  response to surface  seis-
             mic excitation
          •  Fluid/Gas  Vapor  Sampling Cone  -  provides  the acquisi-
             tion of select or continuous samples  of  in-situ liquids
             or  gases,  can  be  used in combination with  in-field
             testing  such a  as  OVA,  HNU,   portable  gas chromatro-
             graphy  unit.

3.2.7  Soil  Gas/Vapor Monitoring
Soil vapor  surveys  are  useful in contaminant  investigations of volatile con-
stituents  in the subsurface media.   The pore spaces between  the  particulate
grains of a  soil  or sediment  media  are  filled with matter in one of the three
elementary forms: solid,  liquid  or  gas.   In-filling  with solid matter results
in reduced porosities and  flow  pathways.   Liquids  and gases on the other hand
are mobile  forms of matter  which are able  to move  through porous  media and
even increase the porosity.

The objective  of  soil  vapor monitoring  is  to delineate  the   extent of soil
contamination and to characterize the contaminants.   Given  the proper subsur-
face conditions, soil  vapor surveys can  be  inexpensive  to conduct and can
provide  data from  a large area  over  a short period of time.   Because soil
vapor sampling is an indirect method of detecting subsurface contamination, it
is considered a  screening  technique to  be  used to aid in the design of a more
focused  sampling plan which  would most  likely include  detailed soil sampling
and monitor wells   installation.   That  is,   information  obtained  during  an

                                     3-83

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initial investigation can then be used to develop an effective follow-up study

which would include the thorough delineation of soil and ground water contami-

nation with soil borings and monitor wells.


3.2.7.1  Liquids and Gases as Flow Media

In saturated  sediments, the  pore  spaces  are  predominantly  filled  with liquids

while a mixture  of  liquids  and  gases  fill  the unsaturated  sediment voids.   As

sediments  become  drained,  a liquid film is  retained  on the  soil  particles by
adsorption and capillary forces while  the  remainder of  the pore spaces become

filled with gases.   If  connected,  the  pore spaces provide  a pathway for vapor

(a mixture of matter diffused in air)  migration.


Several factors  are of importance  in  considering migration  rates  and direc-

tions with respect to the following media:


           a.  Gases  are  generally less  viscous  than  liquids  and
              therefore are  less subject to frictional retardation.

           b.  The  flow  of  gases  and  liquids  are  both  dependent  on
              thermodynamic  factors although  gases  generally  exhibit
              greater  changes  than  liquids   in  response   to  these
              forces.

           c.  Both gases and liquids can be  either  lighter or heavi-
              er than their  standards  (air and water) although  their
              potential  for  vertical   migration  versus  horizontal
              migration is  significantly different.  Volatile  gases
              can  migrate   vertically  up  through  unsaturated  zones
              from  the  water table while light fraction liquids  can
              migrate  to  the  top  of  the  saturated zone  and then
              follow  the  horizontal flow  direction dictated  by  the
              gradient.


3.2.7.2  Soil Vapor Sampling

A variety  of equipment has  been  modified  and  created  for  sampling the vapor

present in the  unsaturated  sediments  at  contamination sites including monitor

wells, well points,  cone penetrometers,  lysimeters  and  soil  gas probes.  Most

involve the use of a vacuum  or suction to collect a sample  of the gas.


The depth  of  sample collection is directly related to the investigation objec-
tives and  location  of  the  contaminant  sources.  Shallow investigations can be
performed  to  evaluate  lateral migration  from near surface  facilities and also


                                     3-84

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to delineate the boundaries of deeper ground water contamination  plumes if  the
overlying sediments are permeable to the  gases  enabling  their  vertical  migra-
tion toward the  surface.   Deeper  soil  vapor sampling  has been  used to  deline-
ate three dimensional  vapor plumes and  thereby  identify  potential  sources  and
the migration direction of discrete vapor plumes.

Another factor affecting the sampling methodology  is  the  volatility or  affini-
ty  for  the  vapor  phase  of  the  constituents.   Constituents  with a  greater
affinity for  water  (highly soluble)  are not good  candidates for this  type of
technology  because  they  would  be harder  to  detect  and  would  be   present  in
decreasing  concentrations the  farther  away the  sampling point  is from  the
source.

3.2.7.3  Sample Analysis
Depending  upon  the objectives  of the  investigation  a  variety of  analytical
methods  can be used.   Simple field  methods and  equipment  such  as cork  bore
samples  in  40 ml septum bottles  and photoiom'zation detectors can  be  used as
screening techniques  for  gross detection  of  volatile  contaminants.   In  more
sophisticated  investigations   where   contaminant   plume  tracking  or  pathway
identification are the objectives, more precise sampling  techniques and analy-
sis equipment  (specialized sampling  probes  and  gas analyzers or  gas chromato-
graphs) may be required.

A two  part  soil  vapor survey is  commonly  conducted  in order to  determine  the
dimensions  and gross  chemical characteristics of  the  area(s) of  soil  contami-
nation.   The first part  of  the survey would utilize a  photoiom'zation field
detection instrument  (PID)  capable of detecting relative units of  total  con-
tamination  concentration  at  each soil  vapor  sampling  location.    Part  two of
the survey  would utilize  a field  gas chromatograph (GC)  to  gain  more specific
data  with   regard  to  the major  chemical   constituents  present  at  strategic
locations  within  the contaminated  area.   The  GC  data will  also  indicate
whether  significant   biodegradation  of  the contaminants  has  occurred  at  the
site.   In addition,  this  instrument  is  capable  of detecting lower  contaminant
concentrations than  the PID unit used  in  the  first  part.  In some cases, it
may also be possible to utilize  GC  equipment which  is already on-site in  the
facility's  own  laboratory,  which  could result  in  a  savings  for  the facility.
                                     3-85

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The  data  from  both parts of  the  survey can  then be  used  to delineate  the
potential boundaries of  a contaminant  plume and areas within  the  plume  where
the contamination exhibits differences in its chemical  composition.   The data
can  also  indirectly indicate the degree  of biological  activity at  the  site,
which is useful in  assessing the feasibility of in  situ  biological  remediation
of the contamination should it be necessary.
                                     3-86

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4.0  MIGRATION OF CONTAMINANTS/AQUIFER CHARACTERIZATION

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            4.0  MIGRATION  OF CONTAMINANTS/AQUIFER CHARACTERIZATION

Regional ground water flow has been described in a  previous  section.   We must
now be  concerned with the introduction  of  a contaminant into an  aquifer and
describe how  that contaminant moves away from  its  source.   It  is an  under-
standing of these processes which  will  provide the  background  necessary  to
design  monitoring  systems  for disposal  sites and to  determine the extent  of
contamination.

Figure  4-1  shows  a  generalized  picture  of  how contaminants are  transported
from their  source  (lagoon,  landfill,  etc.) through the unsaturated  zone to the
water  table,  creating a contaminated  ground water mound  below the  disposal
sites and then flowing down the ground  water gradient.

4.1  UNSATURATED ZONE
In the  unsaturated section, the prime considerations are its  thickness, compo-
sition  and  permeability.

4.1.1   Effect of Thickness
The thicker the unsaturated section,  ttie  longer  it will take  for  a  contaminant
to percolate  downward to the water table.   Solid waste disposal  sites in arid
environments  are generally considered to  generate fewer .problems  than  those in
humid  areas.   Two reasons for  this  are:   (1)  the  unsaturated section  has a
greater thickness, and (2)  less rainfall  percolates  through the disposal  site,
and less water  and/or  leachate  is  available for recharge.   With  no or limited
water moving  through a landfill,  there  is  very .limited  water to percolate to
the  ground  water.   Most  of  the  water  that does  move into  the  unsaturated
section will  either  evaporate or be absorbed into the  soil  moisture.  However,
with liquid waste  disposal, an unlimited  water supply  is available  to  the site
which,  with percolation,  can  create  a  localized saturated   section  from the
surface to  the deep water table.  In  the High  Plains of Texas,  holding ponds
have contaminated  ground water after passing through  200  feet of  unsaturated
deposits.   A  thick,  unsaturated section  in an arid  climatic region  is  a retar-
dant to contamination transport, but not  necessarily an absolute  barrier.
                                      4-1

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4.1.2  Effect of Composition
The  composition (i.e., stratigraphy and  minerology)  of the unsaturated  zone
will  strongly  influence  the fate  of  a  contaminant  migrating  from a  waste
unit.'   The path that  the migrating fluid must  follow  is dependent  upon  the
stratigraphic profile  which  underlies  the waste unit.  Two  different strati-
graphic profiles underlying  similar units (Figure 4-2)  will result  in  widely
varying arrival times  and concentrations  for the same  waste.   Fluids migrating
through a  predominately sand environment  (Figure  4-2A)  will tend  to migrate
vertically  through  the sediments until the  water table is  impacted.   As  the
fluid migrates  through the sand  body any  in  situ pore water will be displaced
and  mixed  with  the migrating waste front, which will result in  a longer time
until the undiluted waste reaches the water table.  Fluids migrating through a
mixed environment  (Figure 4-2B)  such  as  those  normally found in  the Coastal
Plain areas (and other deltaic areas) must follow a longer, more  tortuous path
before reaching the ground water.  This path, while it will not prevent ground
water impact,  allows  a greater  chance for the waste constituents  to be oxi-
dized or adsorbed by the unsaturated sediments.

The  lithologic  composition of the unsaturated sediments  will  determine whether
the  waste  constituents are attenuated-or  degraded  prior  to reaching the water
table.    Sediments  which contain  significant  quantities  of  clay  minerals
(illite, montomorillinite, etc.)  have the ability to adsorb and degrade a wide
variety  of waste  constituents.    Wastes  which  contain  metals  will  realize
significant immobilization  of the  metals  as  they pass  through  the clay-rich
sediments.  So  long as the pH of the sediments remains neutral  to mildly basic
the  metals will be  adsorbed onto  the clay matrix and  not be  available  for
transport  into  the ground water.   The clay-rich  sediments  also provide good
opportunity for biodegration of organics by containing existing  colonies of
micro-organisms.   The  biodegradation of  the organic  wastes  again will  reduce
the  volume of  the  waste constituents available  for  transport  to  the  ground
water.   A third  consideration  of  the  lithologic composition  is  the water
retention  capacity of  fine grain sediments.   A  general  rule is that the finer
the  particle  size  of  the sediments, the  higher  the water holding capacity of
the  sediments.
                                      4-3

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                                                                         DEFINED
                                                                       DOWNGRADIENT
                  Figure 4-2a.   Unsaturated  Zone  Predominately  Sand
 DESIGNATED AS
 DOWNGRADIENT
    RELATIVE
TO AQUIFER IMPACT
LINES OF
SEEPAGE
                                                                         DEFINED
                                                                       DOWNGRADItNT
                 Figure 4-2b.   Unsaturated Zone Typical  of Amarillo Area
            Figure 4-2.  Effects of Unsaturated Zone Lithology on Contam-
                         ination Migration.
                                             4-4

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4.1.3  Effect of Unsaturated Permeability
In  the unsaturated  zone,  permeability  is also  an  important  parameter  for
transport  beneath  landfills and  lagoons.    The lower  the  permeability,  the
slower the velocity of  contaminant transport.   A decrease  in  the  permeability
by  an  order  of  magnitude,  will cause  the rate of  contaminant transport  to
decrease  by  about an  order of magnitude.    Instead  of a hypothetical  travel
time of 10 years,  the  lower permeability material  would  have  a  travel  time of
100 years.

Permeability of the underlying  sediments becomes more  important as  the thick-
ness  of  the  unsaturated  sections  thins.    It  must  be  realized  that  the
permeability  of unsaturated sediments  change  as water is introduced  into  the
matrix.  The term unsaturated permeability  of soils is widely  misunderstood to
indicate  that  the  sediment will always  have  this  permeability.  As  shown in
Figure 4-3,  as the moisture content  of  the sediments  increases  and  approaches
saturation  the permeability of the sediments  increases  dramatically.   This
increase  in  moisture content can easily  be extrapolated  to  the  situation of a
liquid waste front passing  through  the unsaturated  zone.   As illustrated, this
increase  in  permeability  can easily exceed  3 to 4 orders of magnitude.

Monitoring  the permeability of in  situ  soils near  a waste management unit
requires  a combination  of laboratory and field testing.   Determination of the
unsaturated  permeability of  soils  over  a variety  of  moisture  contents  is
necessary to estimate the permeability of the fine  grained sediments under the
waste management unit under changing conditions.  The unsaturated  permeability
can  be  measured  by a  variety  of methods  including steady  state  methods,  in-
stantaneous  profile methods and  pressure plate methods.   These  techniques are
described  in detail  by Roy E.   Olson and David E.  Daniel  ("Measurement of the
Permeability of Fine Grained Soils," ASTM Symposium on Permeability  and Ground
Water Contaminant  Transport, June  21,  1979,  Philadelphia,  Pennyslvania).  Use
of these  methods requires that  the  investigator be familiar with  the in-place
conditions of  the  site and have the ability  to monitor  the  conditions at the
site to detect changes  in the water content of the  sediments.
                                      4-5

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 100F
     0      20     40     60    80      100

           Degree  of Saturation, %
Figure 4-3.  Suction and Permeability Versus Degree  of
           Saturation for Compacted Fine Clay.
           (Olson and Daniel ,  1979)
                     4-6

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Several  methods  are  available  to  track the  water  content of the  subsurface
soils.   Of  these  methods,  tensiometers  are  the  most  commonly  used.   A tensio-
meter measures the  negative  pore water pressures that develop when  a- soil  is
partially  saturated.    This  pore  water pressure  must be  calibrated in  the
laboratory to each sediment type that underlies  the waste  management unit over
a  range of  water  contents.    Unfortunately,  the tensiometer  is  limited  to
approximately  0.9 atmospheres  of  negative pore  water pressure  that it  can
monitor  under ideal conditions, and in most cases this represents a  saturation
of the sediments  in excess of 90 percent (Figure 4-3).  A  more flexible method
with  a  wider range is the use  of  a neutron backscatter probe to measure  the
water  content  of  the soils.    This method must  be  calibrated  to  laboratory
results  of  permeability  versus moisture content  and can  be used over  a much
wider range of correlated permeabilities.

4.2  SATURATED ZONE
Once  the contaminant  has reached the water table,  several  additional parame-
ters have to be  considered:   (1)  direction and  gradient  of ground water flow,
(2) permeability  of the  aquifer,  (3)  density  of the  contaminant  in  comparison
to the  ground water,  and (4)  the chemical  reactivity of  the fluids  and native
ground water.

4.2.1  Direction  and  Rate of Ground Water Flow
Calculations  of   direction  and  rate  of ground water flow  from a  pollutant
source  are  essentially  the  same as  those  described for the  regional  ground
water flow  systems.   In general,  contaminants  enter  the ground water system
and  are transported  along  flow  lines  (Figure  4-4).   Since  flow   lines  are
parallel and  do   not  cross,  theoretically  there is  no dilution.  However,  in
real aquifers, there  is  a dilution of the contaminant, and the average concen-
tration  of  the contaminant will  be  less than  its initial  input.   This results
from  the mechanical  phenomenon  known as longitudinal and  transverse disper-
sion.    Dispersion  is  the mechanical  mixing  of  waters  on   the microscopic
level.   On  the macroscopic level,  flow  is  considered laminar and,  therefore,
flow  lines  do  not cross.  On  the microscopic  level, however,  flow  lines con-
verge  and  diverge  and  actual  velocities will  be  greater or  slower  than  the
average  velocity.   The contaminant  plume from a single,  one-time injection of
a  contaminant  is  an   ellipse  with  concentrations  increasing  toward  the
                                      4-7

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          Flowlines
       Zone of
     Contamination
                        Plan View
Figure 4-4.  Schematic Diagram of  Flowlines  in the Vicinity
             of a Potentiometric f'ound
                               4-8

-------
center.   In  Figure  4-5(a),  a contaminant plume  from  Idaho Falls,  Idaho,  is
wider  than  it  is  long.   However,  the longitudinal radius of a  contaminant
plume  (down  the hydraulic  gradient)  is generally much  longer  than  the  trans-
verse  radius  (perpendicular  to  the  gradient)  as shown  in  Figure 4-5(b).   The
ratio  of  longitudinal  to  transverse dispersion  is  quite different  for  these
two cases.  An  important controlling parameter of the shape of  the  contaminant
plumes is the heterogeneous and anisotropic nature of the aquifer.

The recharge  from a contaminant source  creates  a "recharge mound."  The  in-
crease  in water moving  to the water  table  causes  this  surface  to  rise  and
create a  bulge  on what had been previously a  gently dipping,  planar surface.
Therefore, the  ground  water  gradient at the mound  is  greater  than  the  normal
local  gradient, and ground water will flow out from the mound at a  faster rate
than  the  normal ground water  flow  rates  in the  area.   Figure 4-6  shows  the
effect  on the  potentiometric  surface of  a recharge  mound and diagrams  the
profile  through the  mound.    Similarly,   Figure 4-7  shows a  potentiometric
surface  before and  after seepage  from settling  ponds began  to   impact  the
ground water.   As  previously described, ground water flows down the hydraulic
gradient.  In the case of  the recharge from the hypothetical pollutant source,
ground water  flows down the recharge-mound  in all  directions.  A  pollutant,
therefore, can  migrate up  the regional  hydraulic gradient.   How far the  pollu-
tant migrates up the regional gradient is dependent on  the height  and slope of
the mound and  slope  of the regional  water  table.  Pollutants can  therefore be
expected  hydrologically  up-dip  from the waste disposal  site and  it cannot be
assumed that the pollutant will only be evident down-gradient.   Similarly,  the
plume  will  widen  and decrease in concentration  down-dip.   In  some  documented
cases,  the  plume  became  as wide  as  it was  long for  a very  gently sloping
ground water surface.

4.2.2  Permeability
The rate, direction, and degree of  dispersion  of our hypothetical  waste plume
is controlled by the permeability of the sediments as well  as the  shape of the
potentiometric  surface.    As has been  described  in  the regional  ground water
flow section and the unsaturated flow of contaminant section, flow velocity is
proportional to permeability.  Decreased permeability by an order of magnitude
will lead to transit time  decreased by the same amount.
                                      4-9

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          DIRECTION OF

       GROUND-WATER FLOW
                     DISPOSAL
              a) CHLORIDE  PLUME, INEL, IDAHO
                 Transverse dispersivity '. 450 feet

                 Time !  16 years
              DIRECTION OF

           GROUND-WATER FLOW
                                         O
                                         o
                                         O
                            1000 ft
                                 — J
              b) CHROMIUM PLUME ,  LONG ISLAND

                  Transverse  dispersivity ", 14 feet

                  Time " 13 years
Figure 4-5.   Effect of  Differences  in Transverse
               Dispersivity on  Shapes  of Contamination
               Plumes  (Miller,  1980)
                          4-10

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                                                                     N

                                           • xlmum ultimate extent of
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   30
   25
   10
                     Qualolote Mill
                           Well
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             SW
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             Restored
              natural
              gradient -
                                                          Profile ol potentlometrlc aurfaca
               2000
                          4000
                                     6000
                                               8000
                                            Distance, feet
                                                         10,000
                                                                    12.000
                                                                               14.000      ie.000
Figure  4-6.
Altitude of  Water Levels,  Deep  Aquifer,  Showing  Mounded  Water
Surface  Under a  Cooling Lake  Near  Corpus Christi,  Texas, April
14,  1981.
                               4-11

-------
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-------
Permeability  in sedimentary deposits  is  heterogeneous.    All  sands and  muds
associated  with fluvial  and  deltaic  depositional  episodes  are  heterogenous
because of  the  varying  water energy  that  carried  the  sediment  to its point of
deposition.   The Beaumont  Clay, which  is the surficial  formation  in  most of
the Texas coastal zone, is an ancient delta plain.  Though  it is predominantly
mud,  it  is  interlaced  with sands channels.   This heterogeneity affects  our
hypothetical  contaminant  plume in two ways:   (1)  pollutants  will  move  more
rapidly  through the  highly permeable  materials,  since  flow  lines will  be
concentrated  in the  highly permeable  materials  (needless  to  say,  monitoring
wells should  be located  in  the  sands and  not the  muds),  and  (2) the heteroge-
neity causes  lateral  dispersion of  the  plume (the more the fabric  or aniso-
tropic nature of the deposits  are perpendicular  to flow,  the  more  the plume
will spread laterally).

4.2.3  Density  of Contaminant Plume
The flow of the contaminant in the regional ground water  flow system is depen-
dent  on  the  density  of  the contaminant  in  comparison to  the density  of  the
ground water (density  (p)  of  water  =  1.0).   If the contaminant  density is
about  equivalent to  the  density of the  ground  water,  the entire  saturated
section would be affected  (Figure 4-8)-.   However,  if  the contaminant plume is
heavier  than  the ground  water (pp]ume > 1.0),  it will tend  to sink  to  the
bottom  of  the   aquifer.   Generally,  the more  concentrated  the  contaminant
solution,  the  higher the  density.   Brine  from oil  and  gas  production  is  a
typical  example of  a dense concentrated fluid,   as  is  the  waste  from  many
petrochemical facilities.   Figure 4-9A  is  a hypothetical  cross  section  of  a
disposal site in the  Texas Gulf Coast area showing a denser fluid migrating to
the bottom of the aquifer.

In  contrast,  contaminants  less  dense  than  the  ambient  ground  water  (Pp-|ume
<1.0) will  float on  top of  the ground  water (Figure 4-9B).  Hydrocarbons and,
specifically, gasoline  contaminant plumes float  on top  of  the  ground water.
Gasoline moves  at the water table  and  in the capillary fringe above the water
table.

In  the case of   a heavy  leachate  (Ppiume  >^'  monitor wells  completed  only in
the upper  portion  of the water table  may miss the contamination or at least
                                     4-13

-------
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-------
               IMPOUNDMENT
         z\
Figure 4-9A.
Contaminant Plume with Density Greater than Ground
Water
                 IMPOUNDMENT
            r\
 Figure  4-9B.   Contaminant  Plume with  Density  Less  the  Ground  Water

                                 4-15

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indicated  lower  concentrations  of  pollutants.   When  P <  1, monitor  wells
completed  in  the  base of an aquifer might  completely  miss  the contamination.
Figure 4-10 is an example of shallow monitor wells missing the contaminant and
the deeper wells'  indicating contamination.

4.2.4  Chemical Reactions
So far,  the  discussion of the contaminant  plume,  its  shape  and movement, has
been based  on physical  aspects  of  the system, flow rates,  permeability, and
densities.   The chemical reactivity of  the contaminant  is  another  important
factor  in  determining where and how  far the plume migrates.   Similarly, the
geochemical environment  of  the aquifer is  an equally  important factor.   Both
these factors  are  important  in both the  saturated  and  unsaturated sections of
the aquifer.

Contaminants  can  be  either  reactive or nonreactive.   Nonreactive contaminants
are extremely soluble anions or small non-ionic organic  molecules  which move
through  the  systems  at  approximately  the same velocity  as  the ground water.
For example,  chloride (leaking  from a brine disposal  pond)  is a nonreactive
anion.   A  contaminant  plume  of chloride  will  not be  retarded by  chemical
reactions.   Because  of this,  chloride-and  bromide  (similar  to chloride) have
commonly been  used as  tracers  in ground water flow experiments.

Reactive  contaminants   are  retarded  in  an  aquifer  in  several   different
fashions,  depending  on the  type of  reaction involved.   Examples of reactive
species  would be the  divalent cations Ca"1"*" and Ba"1"1",  ammonium (NH^4^),  trace
metals,  and acidity.   Cations  such as  NH4+ react with clays by a process known
as  cation-exchange.    Clay  particles  carry  negative  charges  on their sur-
faces.   In  a natural  systems,  the  negative  charge  points  are occupied  by
cations.   If  an  ammonium solution flowed  through these clays,  the ammonium
would replace  some of  the other cations already in the clay.  There would be a
loss of  ammonium from the  contaminant plume.   The problem with  this  type of
retardation  of a  contaminant  is that the  reaction  is reversible.   Once the
ammonium plume had flowed past the clay  particle,  the particle would release
some of  the ammonium to  bring  it into  equilibrium with the new solution.  This
type of  reaction  retards the movement  of  a contaminant but does not completely
eliminate the  contaminant.
                                     4-16

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 a
MW-1
                                                                                                  EXPLANATION

                                                                                         MW-1 d   Monitor wel

                                                                                            22     Contour of water table

                                                                                         ——^^"ป  Direction of contaminated
                                                                                                     groundwater flow
                                                                                          Total Dissolved Solids content
                                                                                          of samples from monitor wells
WELL
MW-1
MW-2
MW-7
MW-8
MW-9
MW-10
DEPTH
45
25
48
30
30
48
IDS
330
450
95.000
4,300
3,900
78,000
     MW-1
                     MW-2
                                                                                           MW-8
                                                                                                MW-7
         Fine silty sand
         KS1 x 10 ~2
            cm./sec.
                                                    Dense leachate
                                                      density  > 1
 Note:  A recharge mound is not indicated.
      The site wai drained & capped prior
      to monitor wel inetalation.
                                                                                                   Zone of gravimetric
                                                                                                       separation
     Stiff clay

K s 1 x 10 ~*  cm./sec.
           Figure  4-10.    Cross Section  of  Disposal  Site  on  the Texas Gulf Coast

                                                          4-17

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Adsorption  of  trace  metals  on  the  aquifer  matrix  is  another  process  of
leachate  attenuation.   This  process  differs from cation-exchange in  that  (1)
adsorption is not dependent on clays  with high  cation exchange capacities,  (2)
an ion is not released for every metal  ion adsorbed,  and (3)  the reactions  may
or may not  be reversible.  Examples of  metals that  are adsorbed  are  chromium
and copper.   In one Texas Gulf Coast  disposal  site,  leachates contained 5 mg/1
of copper.    However,  in nearby contaminated  monitor well   (approximately  10
feet from  the disposal site), only .064 mg/1  of copper was  detected  in water
samples.    Similarly,  in a disposal site located in  the northern  High Plains,
suspected contamination  of  a  site water well   by leachates occurred.   Despite
high levels of chromium and lead in the plant  leachates, the  contaminated well
water  showed  negligible  levels  of these  constituents,  which  has  apparently
been attenuated by the uppermost soils.

Acidity  in  a contaminant plume  is altered in an  aquifer by reaction  of  the
hydrogen  with the  carbonate  minerals  in  the  aquifer  matrix.    Acidity will
react  with  calcite  to form  bicarbonate.   An  increase  in  bicarbonate  in  an
aquifer  is  generally  not considered  a problem.   If the  aquifer lacks  the
carbonate minerals,  then  acid  plumes ean continue.   Acid  mine drainage occurs
in the  northeastern United States because  the rocks in which  the  acid water
flow are very low in carbonate minerals.

Many  contaminants will  precipitate  out of solution,  because specific ions
become oversaturated either by reacting with the aquifer  or  by changes  in the
pH in  the redox environment of the aquifer.   Iron is very soluble  in acidic,
reducing waters as  the ferrous  ion fe   .  Oxidation  of the iron solution will
lead to  the shifting  of  the  ferrous  ion to ferric iron  (fe   ),  which is  ex-
tremely insoluble and  will precipitate as an iron hydroxide.

Although  the  preceding  discussion indicates  leachate migration  is a complex
subject,  in most ground  water contamination  studies,  some   estimates  of  the
lateral extent  of contamination  must be made.   Generally,  insufficient funds
and  little  time  are  available for comprehensive investigations.   Therefore,
estimates of  lateral migration are made  on the basis  of Darcy's Law.
                                     4-18

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4.3  AQUIFER CHARACTERIZATION TESTS
In order  to  assess the various hydraulic parameters which  affect  contaminant
migration, a variety of  tests  can  be  performed.   These  tests  consist of field
tests  which  measure  and  determine   aquifer  characteristics   and  consist  of
laboratory testing of soil samples and aquifer matrix.

4.3.1  Field Tests
Aquifer  characterization  tests  conducted  in  the  field   (pumping,  aquifer,
drillstem, etc.)  are generally considered to  be more reliable than laboratory
tests used for determining hydraulic  characteristics of  aquifers.   These tests
generally involve  the removal of water from an aquifer by pumping  a well while
the  subsequent  reaction  of  the aquifer  to this  imposed  stress   is  observed
simultaneously.

There  are two different  types of analyses used  in the determination  of  hy-
draulic characteristics;  steady  state (equilibrium)  and transient  (nonequili-
brium).   Both of  these  types of  analyses  are  described  in Section  4.3.1.2  and
4.3.1.3 respectively.  Section 4.3.1.1 is a list of the  definitions of some of
the terms frequently used  in these sections.

4.3.1.1  Aquifer  Characteristics Definitions
ANISOTROPY - is the condition under which one or more of the hydraulic proper-
ties of an aquifer vary with respect  to the direction within the aquifer.

HEAD  (TOTAL)  -  is the  sum  of  head  resulting from  elevation, pressure  and
velocity at a given point  in an aquifer.

HYDRAULIC  CONDUCTIVITY  -  is  the  capacity of  media (sediments  or  rock)  to
transmit  water  of a  prevailing  density  and  viscosity  through a  unit  cross-
sectional area of  an aquifer.  Hydraulic conductivity is equal to  transmissiv-
ity divided by the aquifer thickness  (Figure  4-11).   The term "coefficient of
permeability"  was used  in  the  past  although  hydraulic  conductivity  is  now
preferable.   This has  resulted  in some confusion with  respect to  the  use of
the term permeability.
                                     4-19

-------

msm
I ^Sro pg^-^f
   4-20

-------
HYDRAULIC GRADIENT -  is  the  change  in total  head  for  a change  in  some  unit  of
distance in the direction of maximum decrease in head  (Figure 4-12).

ISOTROPY -  is the condition  in  which  the hydraulic properties of an  aqufier
are equal in all directions.

SPECIFIC CAPACITY - is the yield of a well per unit of drawdown.

SPECIFIC RETENTION -  is  the  ratio  of the  volume of water retained in a porous
media sample after gravity drainage has  occurred.

SPECIFIC YIELD - is the ratio of the volume of water that will  drain  under the
influence of gravity to the saturated media sample.

STORAGE  COEFFICIENT  - is the volume of water  released  from storage  in a unit
volume  of  an  unconfined quifer by  lowering  the  head a  unit  distance.   In
unconfined aquifers  the  storage  coefficient  equals the specific yield  because
water is released from storage.  The release of water per unit  decline  in head
is much  greater for unconfined aquifers than for confined aquifers where other
properties are similar (Figure 4-13).

STORATIVITY -  is the  volume  of  water  released  from storage per unit  volume of
a confined  aquifer per  unit  change  in  head.   In  confined aquifers, water  is
released from the aquifer's  pore  spaces  from  the compression of the grains
within the aquifer (Figure 4-13)

TRANSMISSIVITY  -  is  the  rate at which water of a  prevailing density and vis-
cosity is transmitted through a unit width of the fully saturated  thickness of
an aquifer under a unit hydraulic gradient.  It is a function  of properties of
the liquid,  the porous media, and the thickness of  the porous  media.   Trans-
missivity  is  equal  to  the hydraulic conductivity multiplied  by  the  aquifer
thickness.   The term  "transmissibility"  was used in  the  past  and has almost
completely been replaced by transmissivity in literature (Figure 4-11).

4.3.1.2  Steady State  (Equilibrium) Method
The steady state method was the first method developed for aquifer test analy-
                                     4-21

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sis.   For this  method,  the  test  must remain  in  progress until  the  aquifer
reaches  equililibrium from  the  imposed stress  (pumping).   This requires  a
relatively  long  testing  period  (until equilibrium  is  reached).  In  reality,
equilibrium  may  not be  an  achievable  goal  if one  or more the  ideal  aquifer
assumptions are not met.

STEADY STATE ASSUMPTIONS
The use of steady state  equations is based  upon the following assumptions:

          -  The  formation  is homogenous  (characteristics are  uni-
             form  areally),  isotropic  (hydraulic   properties   are
             equal in all directions),  and  of uniform thickness.

          -  Hydraulic  characteristics  of   the  formation and   any
             confining  layers  are  constant at all  times  and at  all
             locations within the area of influence of the well.

          -  The formation is not stratified.

          -  The discharging well is screened over the entire thick-
             ness of the formation.

          -  Flow to  the well  is horizontal (i.e., the slope of  the
             water table or  piezometric surface  is relatively flat),
             radial  and  laminar  (fluid   particle  flow   paths   are
             smooth,  straight and  parallel) within the  radius  of
             influence of the well.

          -  The  rate  of discharge  from the well  (or imposed stress
             to the aquifer) is constant.

          -  The pumping well is 100 percent efficient.

          -  The cone of depression has reached  equilibrium and  will
             not expand  with continued pumping.
                                     4-24

-------
In addition,  the  method  requires  the use of two or more observation  wells  at
different  radial  distances  from  the pumping  well  for water  level  measure-
ments.   Figures 4-14, 4-15, and  4-16  provide  an illustrative definition  for
various terms used in equilibrium methods.

STEADY STATE  (EQUILIBRIUM, OR THIEM)  EQUATION METHOD
The equilibrium method can be employed  to evaluate  the aquifer  characteristics
around a pumping well.  This method is  accurate for determining transmissivity
(T) and/or  hydraulic  conductivity  (k)  but  not  storativity or  specific  yield,
which are both designated as (S).

The appropriate form of the equation  used in the analysis  of  unconfined  (water
table) aquifers is:
    English Engineering Units

        1055 Q log (r2/r1)
     k=
         (h2
International  System of Units
k=
    Q  log  (r2/r1)

    1.366  (h22-  t^
where:
Q = well yield or pumping rate, in gpm
k = hydraulic conductivity of the water
                                •)
    bearing formation, in gpd/ft
r-^ = distance to the nearest observation
     well, in ft
r2 = distance to the farthest observation
     well, in ft
h2 = saturated thickness, in ft, at the
     farthest observation well
h-^ = saturated thickness, in ft, at the
     nearest observation well
Q
K
rl

r2

ho
= well yield or  pumping  rate,  in  gpm
= hydraulic conductivity of  the Water-
                         's      o
 bearing  formation,  in  nr/day/m
 (m/day)
=  distance to the  nearest observation
   we!1, in m
=  distance to the  farthest
   observation well,  in  m
=  saturated thickness,  in m,  at  the
   farthest observation  well
=  saturated thickness,  in m,  at  the
   nearest observation well
                                     4-25

-------
               Ground surface
                                          Impermeable
                                     '/X////////////////////
                        Impermeable
CARTER TODD, 1976D

Radius of weil-^
fl
f*- Radius of influence-
^^ ^ Cone of
"\^ depression
X
Drawdown curve^ \
(potentiometric surtacer
^mp^o^str^gmX
b
Thickness of
water-bearing
formatjon
T


w
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f Depth to static
potentiometric surface
'Draw
/ in v
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down
veil.
h
•

• i

             CAFTER DRISCOLL, 1986)
  Figure 4-14.  Various Terms Used in  the Equilibrium
                 Equation  for a Confined  Aquifer
                            4-26

-------
                 Ground surface
                          permeable
CAFTER TODD. 19763
               CAFTER DRISCOLL. 1986}
Figure 4-15.   Various Terms Used in  the Equilibrium
               Equation  for an Unconfined Aquifer
                             4-27

-------
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and for confined (artesian) aquifers:
    English Engineering Units
                                            International  System  of  Units
 T = kb =
where:
           528 Q log (r2/r1)
             (h2 -
all  terms  except the  following  are
the same as for unconfined aquifers
 b = thickness of the aquifer, in ft
     head, in ft, at the farthest
     observation well, measured
     from the bottom of the aquifer
     head, in ft, at the nearest
     observation well, measured
     from the bottom of the aquifer
ho =
hl =
                                            T =  kb  =
                                                        Q log  (r2/r1)
                                                        2.73  (h2  -
all terms except  for the following  are
the same as  for unconfined aquifers
 b = thickness of an aquifer, in m
h2 = head, in m, at the farthest obser-
     vation  well, measured from
     the bottom of the aquifer
h^ = head, in m, at the nearest obser-
     vation  well, measured from
     the bottom of the aquifer
4.3.1.3  Transient (Non-Equilibrium, Non-Steady) Methods

The transient methods differ from the steady state methods in that the expand-

ing cone of depression does not have to reach equilibrium in order to evaluate

the data determining aquifer characteristics.


Specific Capacity Method (Modified Thiem Formula)

A modification  of the  Thiem  equilibrium  formula enables a rapid approximation

of transmissivity.   This method  uses  the pumping test  parameters,  discharge

(Q) and  maximum drawdown  (Sw),  to  determine  specific capacity from  which  a

value of transmissivity  can  be derived.   The transmissivity of the aquifer is

calculated using the following formulas:


                   T = specific capacity x a constant
where:  Specific Capacity =
                            Sw
                                     4-29

-------
and:
     T = transmissivity in gallons/day/foot (gpd/ft)
     Q = discharge during pumping in gallons per minute (gpm)
    Sw = maximum drawdown in the well in feet
    Constant = a number in the general range of 1,700 to 2,000
TRANSIENT ASSUMPTIONS

The following assumptions apply to the transient methods.


          -  The  formation  is homogeneous (characteristics are uni-
             form  areally),   isotropic   (hydraulic  properties   are
             equal  in  all  directions), of uniform  thickness and of
             infinite areal extent.

          -  Hydraulic  characteristics  of  the  formation  and   any
             confining  layers  are constant at  all  times and at  all
             locations within the area of influence of the well.

          -  The  discharging  well is  of  infinitesimal  diameter  and
             is screened over the entire thickness of the formation

          -  Flow  to the well  is  horizontal  (slope  of water  table or
             piezometric  surface  is  relatively  flat),  radial   and
             laminar (fluid particle flow  paths are smooth,  straight
             and  parallel)  within  the radius  of  influence  of  the
             well.

          -  All water  is released from storage instantaneously with
             the  lowering  of  the head and there  is no  delay in  the
             reaction observed.

          -  The  formation  has  no  points of  discharge or  recharge
             within the area of influence.


THEIS GRAPHIC NONEQUILIBRIUM METHOD

Theis developed the nonequlibrium well equation based upon the analogy between

the flow  of water  in  a confined aquifer  and  heat flow  in  a thermal conduc-

tor.  This  equation was the  first to  take into account the  effect  of pumping

time and, thus, provided for the determination of transmissivity  and hydraulic

conductivity from  early stages of pumping, without ever reaching  equlibrium.
                                     4-30

-------
Theis'  method utilizes a graphical solution which  involves matching  a  plot of

actual  field data with a theoretical  type curve (See example,  Figure  4-17).
          1. Obtain an  existing type  curve,  or plot a type curve to
             a convenient scale on logarithmic paper.

          2. Plot field data (also on logarithmic paper).
             Drawdown (hQ - h)  vs  t.

             Note:   For observation wells^with differing distances
             from the pumping well, use t/r^

Solutions for transmissivity, (T)  are as follows:
          English Engineering Units
                                            International  System of Units
         T =
                114.6 Q W(u)
                   h0 - h
                                            T =
                                                   1 Q W(u)
                                                     (h0 - h)
where:
h  - h =
         drawdown, in ft, at any
         point in the vicinity of a well
         discharging at a constant rate
     Q = pumping rate, in gpm
     T = coefficient of transmissivity
         of the aquifer, in gpd/ft
  W(u) = is read "well function of u"
         and represents an exponential
         integral
h  - h =
       drawdown,  in m,  at any point
       in the vicinity  of a well
       discharging at a constant rate
       pumping rate, in m /day
       coefficient of transmissivity
       of the aquifer,  in m /day
W(u)  = is read "well function of u"
       and represents an exponential
       integral
                                                 Q
                                                 T
Solutions for the coefficient of storage (S) are as follows:
          English Engineering Units

                uTt
                                            International  System of Units

                                                  4uTt
       S =
where:

r = distance, in ft, from the center of a
    pumped well to a point where the
    drawdown is measured
S = coefficient of storage
    (dimensionless)
                                            S =
                                            r = distance, in m,  from the center of a
                                                pumped well  to a point where
                                                the drawdown is  measured
                                            S = coefficient  of storage
                                                (dimensionless)
                                     4-31

-------
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-------
T = coefficient of transmissivity,  in       T = coefficient of transmissivity
    gpd/ft                                      in m /day
t = time since pumping started, in  days     t = time since pumping started, in days
Numerous - adaptations  and  modifications of this  method  have been derived  for
specific situations including type  curves for leaky aquifers (Figure 4-18)  and
developed yielding aquifers.

JACOB'S STRAIGHT LINE METHOD
It  was  postulated  by  Jacob  that,  after steady  state  conditions had  been
reached, higher values  in  the  infinite  series  become  negligible;  thus,  a more
simple equation, could  be  utilized to  achieve  approximately the  same value as
Theis' equation.

Jacob's  solution  to  the  Theis equation  also utilizes  a  graphical  solution
except the  slope of a line intercept is used instead  of the matching of field
data  to  a  type curve  (See Figure  4-19).   The Jacob  method applies, however,
only when the well radius  (r) is small with respect to time (t).

Steps:

          1. Plot drawdown against  time on semi logarithmic paper.
          2. Draw a straight line through plotted field-data points.
          3. Extend  line   to  the  zero-drawdown  axis  and  note   the
             value of tQ
          4. Measure value of drawdown per log cycle.

The aquifer  characteristics of transmissivity and  storage  coefficient  can be
calculated using the following equations:

Solutions for transmissivity (T) are as follows:

English Engineering Units                   International System of Units

      264Q
 T = 	                                T = 2.3 q_ = 0.183 Q
       AS                                       4ir  AS      AS
                                     4-33

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          4-35

-------
where:

T  = coefficient of transmissivity,  in
     gpd/ft
Q  = pumping rate, in gpm
AS = (read "delta s") slope of the time
     drawdown graph expressed as the
     change in drawdown in ft over one
     low cycle
T  = coefficient of transmissivity, in
     or/day
Q  = pumping rate in nr/day
AS = (read "delta s") slope of the time
     drawdown graph expressed as the
     change in drawdown in m over one
     log cycle
Solutions for the storage coefficient (S)  are as  follows:
English Engineering Units
International  System of Units
 S =
T =
                                                 2ฐ25
where:

 S = storage coefficient
 T = coefficient of transmissivity, in
     gpd/ft
t0 = intercept of the straight line at
     zero drawdown, in days
 r = distance, in ft, from the pumped
     well to the observation well where
     the drawdown measurements were made
 S = storage coefficient
 T = coefficient of transmissity, in
     nr/day
tQ = intercept of the straight line at
     zero drawdown, in days
r = distance, in m, from the pumped
    well to the observation well where
    the drawdown measurements were made
DISTANCE DRAWDOWN METHOD

The distance  drawdown method utilizes the simultaneous observations  of  draw-

down in three or more observation wells (See example,  Figure 4-20).
Steps:
          1. Plot  drawdown  on  arithmetic  scale  as  a  function  of
             distance from the pumping well on logarithmic scale

          2. Draw  a  line  through  data points for the wells close to
             the  pumping  well  and extend  it  to intercept the zero-
             drawdown line.

          3. Measure the  drawdown per  log  cycle as before  i.e., A(h
             -h).
                                     4-36

-------
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The following equations can then be used  to determine  the  aquifer  characteris-
tics:
English Engineering Units
International  System of Units
          T = 528_
               AS
T = 0.366 Q
       AS
where:
where:
 T = coefficient of transmissivity, in
     gpd/ft
 Q = pumping rate, in gpm
AS = slope of the distance drawdown
     graph expressed as the change in
     drawdown, in ft, over one log cycle
 T = coefficient of transmissivity, in
     m2/day
 Q = pumping rate in nr/day
AS = slope of the distance drawdown
     graph expressed as the change in
     drawdown, in m, over one log cycle
and
          S = 0.3 Tt
  = 2.25 Tt
where:
where:
 S = coefficient of storage                  S
 T = coefficient of transmissivity, in       T
     gpd/ft
 t = time since pumping started, in days     t =
rQ = intercept of extended straight line    rQ =
     at zero drawdown, in ft
   = coefficient of storage
   = coefficient of transmissivity, in
      m2/day
     time since pumping started, in days
     intercept of extended straight
     line at zero drawdown, in m
4.3.1.4  Conducting An Aquifer Characteristics Test
There are three stages to conducting an aquifer characterization  test:

          a. Pre-test  stage:   Check  equipment and measure  the  re-
             sponse and efficiency of the wells.  The optional pump-
             ing rate is determined in this  stage.
                                     4-38

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          bo Drawdown  (pumping) test stage:  Maintain constant pump-
             ing  rate  over a  long period  of  time  and measure draw-
             down.
          c. Recovery  (post-pumping) stage:   Stop  the pump and mea-
             sure recovery of water levels.
Test Requirements:
          •  A reliable pumping system must be used.
          •  All  wells must  be designed for  measuring  water  levels
             in the unit of interest.
          •  Pumped  water  must be  discharged at  a  sufficient dis-
             tance that  it does  not recharge  the aquifer in an area
             which may affect test results.
          •  All  measurements  must  be  referenced  to a  fixed point
             (e.g., the top of each well casing).

Observation Prior to Test:  Water levels in all wells should be measured prior
to  the  test to  establish  any water  level anomalies (e.g.,  tidal  influences
etc.).

Length  of  Test:   The  length of  the pumping test depends on  both  aquifer and
recharge conditons  (e.g.,  stream recharge).   Artesian aquifers  are generally
pumped for a minimum of 24 hours and water table aquifers, for a minimum of 72
hours.

Frequency of Readings:  The most common schedule for measuring drawdown begins
with  readings  taken at  30-second  intervals for the  first 10 minutes  of the
test  (one-minute  is maximum interval).  Subsequent measurements should be such
that an even spread of drawdown data points are obtained  on a  log scale plot.

Staffing:  The test should be run by a qualified hydrogeologist experienced in
dealing with problems  which can be encountered during field testing.

End of  Test:   At the  end  of the test  (after  recovery data has been obtained)
all wells should  be sounded and these data compared with  pre-test soundings to
determine if anomalies have affected static conditions.
                                     4-39

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4.3.1.5  Test Design and Analysis
The  field  procedures used  to  perform aquifer tests  and  the methods used  to
analyze the  data were derived  in  response  to the need for  evaluating  ground
water supplies  for  domestic, agricultural and  industrial  use.   Therefore,  the
tests were  often performed on  a large scale.   With  the  growing  interest  in
ground  water  contamination  investigations  and  hazardous   waste  migration
studies, the use of these tests has been adapted  to a  smaller scale.

Quite often  the water bearing  formation of interest  in environmental  studies
does not fit the scientific definition of an aquifer but rather the regulatory
definition  of  the  word.    As  a result,  these  low to  poorly  yielding  water
bearing units might be  considered  aquitards in  relation  to  major  aquifers  by
water well  industry  standards,  while  the environmental  community would  con-
sider them aquifers.

As  the  scale of the  test is reduced, deviations  from  the  assumptions of  an
ideal aquifer  become increasingly  significant, making it even  more  important
that we realize that these methods only provide  approximate answers.   Objec-
tives must  be achievable  within  the constraint of the situation,  and the test
design must  be  appropriate  to  fulfill  these objectives.   In  designing aquifer
tests and  evaluating the  results,  a  number  of  factors   should be considered
with respect to the scale and objectives of the test:

          -  Can  an appropriate set  of materials  and  equipment   be
             assembled to perform the test?
          -  Can the  test be performed so as to yield adequate data
             for reasonably  accurate  evaluations or are  too many  of
             the assumptions invalidated?
          -  How will the test be analyzed?
          -  Can  all  or  any of the objectives  be  fulfilled by the
             test, which ones,  and  is this adequate?

While many methods  of analysis  have been developed, the evaluation of pumping
test data may  not always be straightforward.  As  a result,  pumping  test data
can be interpreted  in more than one way such that several  factors  must be kept
in  mind  during  data interpretation.    These  factors  include errors  in  data
                                     4-40

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collection,  well  design and construction details,  hydrogeologic  characteris-
tics of  the tested aquifer, accuracy of pumping  rates  and  potential  environ-
mental  influences such as  barometric  effects,  highway and  railroad  traffic,
and tides.

The  calculation  of  an aquifer's transmissivity  using  Jacob's straight  line
method  is  based  upon  the  determination  of  a straight  line  slope  through  the
field data.   In some  pumping  test data,  more than one slope can be determined
over the period of the aquifer test.  Figure 4-21 represents the time-drawdown
plot for  a well  discharging 2,700 gpm.  The  early  time data is attributed to
wellbore  storage  and  is  not  used   in  the  analysis  for  transmissivity  even
though  the data may yield a straight line.   On  the other  hand, drawdown  data
yielding  two separate  straight  line portions  (Figure 4-22)  can  be used  to
indicate  important  physical  characteristics  of the   aquifer.    Figure  4-22
indicates  the boundary  effects within an  aquifer caused by  variable lithology
within a glacial  outwash deposit.

Pumping  test data  can  also be  affected by  sources uncontrolled  by  the  per-
former  of  the pumping test.  The influence  of  these  outside sources  needs to
be  understood  before  an accurate assessment  of  the data can be made.   Figure
4-23  represents  a  plot  of drawdown data  collected from an  observation  well
during a pumping  test.  Because  of the small drawdown in the observation well,
it was necessary  to evaluate the barometric efficiency of  the aquifer and  make
adjustments  to  the water level   data.  While  the actual data collected  during
the  test  is erratic,  the  corrected  data  permits a straight  line  to  be drawn
through  the  latter  time  data.   Changes in  water levels  due to barometric
effects  sometimes exceed the changes  in  water levels  expected from  a  nearby
pumping well.   In  these  cases,  the barometric effects mask  the  test results
and make the data uninterpretable.

The test  data can also be influenced by  surrounding pumping wells in areas of
uncontrolled pumpage of the tested aquifer.  Figure 4-24 presents the recovery
data for  a Travis County,  Texas  well.   The  changes  in the  slope of the recov-
ery data  result from several  nearby wells  being  intermittently turned  on and
off during  the  pumping test.
                                     4-41

-------
         Early data
     40   affected by
        casing storage
     60
     80
    100
    120
    140
    160
                 Q = 2,700 gpm_
                            	—
                            <= 158i40pgpd/ft
                     10             100            1,000

                         Time since pumping began, minutes
10,000
 (After  Driscoll,  1986)
         Figure 4-21.  Time-drawdown Plot for a  Well
                         Discharging  2,700  gpm
     20
   ~- 30 E
   ฃ 40
   Q
     50
     60
     70

                     10             100            1,000
                         Time since pumping began, minutes
(After Driscoll, 1986;
         Figure 4-22.   Drawdown Data for  6-in.(152-mm)  Test
                         Well  in Brewster,  Minnesota
                                4-42

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4-43

-------
Water
 Level
 (FU
         144
         145
         146
147
         148
         149
         150
         151
                           50
                                 100             150
                                    TIME. MINUTES
200
250
                      Figure 4-24.
                            Recovery Data  Showing Effects  of Nearby
                            Interim'ttantly Pumping Wells
                                           4-44

-------
Real world  aquifers do  not meet the  assumptions  made in  establishing  well-
hydraulics  methodology.   Some  deviation  is to  be expected from  "idealized"
type curves.    Calculated  properties  should be  regarded  as being  approxima-
tions.    Therefore, aquifer test data  should  be analyzed by a  qualified pro-
fessional who  is experienced in determining  the quality and validity of the
results.

4.3.1.6  Slug Tests
Slug tests  are  often  used  as  an alternative  or  supplement to  conventional
pumping tests for the determination of aquifer characteristics  (e.g., transmi-
ssivity,  storativity,  hydraulic conductivity).    As  in the  case of  pumping
tests,  aquifer  characteristics  are determined from the  data.   Certain assump-
tions  about the  aquifer's  characteristics  are necessary,  and the  physical
constraints posed  by the  testing method must  be  considered.  In most analytic
methodologies utilizing slug tests, the assumptions concerning  the aquifer are
that it is:
             Homogeneous
             Isotropic
             Areally extensive and
             Uniform in thickness
There are  several  different approaches to analyzing slug  test  data.   In most
ground water  related texts on  the  subject,  the following three  are  the most
commonly referenced methods:

           •  Cooper, Bredehoeft, and Papadopulos (1967; 1973)
           •  Bouwer and Rice (1976)
           •  Hvorslev (1951)

Another  noteworthy method  that  is  not  as  prevalently known  is the  method
described  by Nguyen and Finder  (1981).

The Cooper et  al.  method (1967;  1973)  is  used  to  analyze  confined (artesian)
aquifers,  exclusively.   Bouwer  and  Rice's  method  (1976)  is primarily used for
unconfined  (water  table)   or   semi-confined  aquifers,  although  the  authors
maintain   it  can  provide   accurate  results  in confined  aquifers  as  well.
Hvorslev's method  (1951) is appropriately used where specially designed piezo-

                                     4-45

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meters  have  been installed.   Hvorslev's  method  is useful  in  determining the
hydraulic conductivity  (k)  of fine grained materials such  as  clays and silts
(i.e., aquitards) rather than coarser grained water-bearing formations.  Since
the emphasis  of  this  section  is  toward  aquifer characterization,  the Hvorslev
method will not  be discussed  in any detail.

Testing Procedure
Although there are many  different  analytic  methods  for  slug tests,  the actual
testing procedures are basically the same.  Test  procedures involve either the
injection  into,  or  withdrawal  of  a  slug  of  water of  known  volume  from,  a
well.   The  change in water level  in  the  well  in response  to  the  addition or
removal of the slug  is  measured  over  time with either an electric line, chalk
line, or transducer.  The rate of this response is primarily controlled by the
characteristics  of the  screened  aquifer.   At first,  the  rate  of  the response
is  very fast and then  slowly decays  with time until equilibrium  is reached.
For  this reason,  water  levels  are  collected  initially  at  very  short  time
intervals, e.g.,  every  10  seconds.  As  the response decays, this interval can
be  lengthened to 20  seconds, 30 seconds,  60  seconds,  2  minutes,  5 minutes,
etc.   These data (change  in  water  level  vs. time) are then plotted on semi-
logarithemic paper for analysis using the appropriately selected method.

Description of Methods

          Cooper, Bredehoeft, and Papadopulos Method
          Cooper,  et al.  (  1967  and 1973) described  a  method for
          analyzing  slug test data based  on non-steady flow.   This
          method  utilizes  the plot  of the ratio of  the measured head
          to the  head after displacement  by  the slug  (H/HQ) over the
          function of time.  (See Figure 4-25).   The ratio H/Hg and
          time  are  plotted  on  arithmetic  and  logarithmic scales,
          respectively,  on  semi logarithmic  graph  paper.   The result-
          ing curve  plot will look similar to the theoretical type
          curves  shown  in  Figure 4-26.   A transparent (same  scale)
          copy of the type curve is placed over the field  data plot
          until   an   appropriate  match  of  the  curve   has  been
          achieved.   The  transmissivity  (T) of  a confined aquifer
          can then be determined from the formula:
                              T =  1.0rc2
                                     4-46

-------
                                     Water level immediately
                                     after injection
                                      Water level at time t
                                           Head in aquifer
                                              ^.Initial head
                                                in aquifer
                                        Well casing
                                        Well screen or
                                        wall of open hole'
[Source:  H.  H.  Cooper, Jr., J.  D.  Bredehoeft,  and S. S. Papa-
 dopulus, '-later  Resources Research,  3 (1967)  :263-69)
   Figure 4-25.   Well Into Which  a Volume,  V,  of Water  is  Suddenly
                  Injected for  a  Slug Test  of  a Confined Aquifer.

-------
^Source:   S.  S.  Papadopulos, J. D. Bredehoeft, and H. H. Cooper,
'jr.,  Water Resources Research, 9  (1973):1087-89.
 Fiqure 4-26.
Type Curves for Slug Test in a ;'ell  of Finite
Diameter.
                               4-48

-------
Where r   is  the  radius  of the well casing,  and  ti  is the
value of  time on  the  field  data jjlot  intercepted by the
matched vertical axis where  Tt/r^  =  1 on the chosen type
curve.   The  storativity  (S) of  the  aquifer  can  also be
obtained  using  the value  of the  y-curve  matched with the
field data from the formula:
Where r   is  the radius of  the  well casing  and  r. is the
radius of the borehole annulus or well screen.  The use of
this method  in  the determination of  storativity  has been
described by the  authors  as having  "questionable relia-
bility;"  the accuracy can  be expected  to  be  within two
orders of magnitude of the actual value.

Bouwer and Rice Method

The  slug  test  method described  by  Bouwer and Rice  (1976)
is based  on  steady state  flow theory and is applicable to
both fully  or  partially  penetrating wells  in unconf ined
(water table) aquifers  (Figure  4-27).   The field data are
collected in the same manner  as  previously described.  The
solutions for  characteristics are  similar  to  open  auger
hole techniques  which measure  hydraulic  conductivity (k,
coefficient  of   permeability).    The empirical  equation,
which takes  in  account the  geometry of the well (or piezo-
meter), and  is  used  in determining  k  from the water dis-
placement by a slug, is:
           k = rc2 1n
                      2L
                                   yt
The  effective  radius  term,  R ,  is  the  equivalent  radial
distance over  which  the  head loss y is dissipated through
the system during the  test.   Rg  is dependent upon  the geo-
metry of the flow  system.   The  value of Re, which is used
in  the  previous formula  as  Re/i"wป  must  be derived using
the  following  equation  for  a partially  penetrating well
(i.e., D>H):


 In R0/r
     e  w      1.1       + A + B In [(D-H/r )
              ln(H/rw)

Where  A  and  B  are dimensionless  coefficients  that  are
functions of L/r , as shown in Figure 4-28.
                W

If the  well  being tested  is  fully  penetrating (i.e.,  D  =
H) then the previous formula should be modified to
                           4-49

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/"•
2rc
I
y
T t
1

VXVปWW/X/^
f/SXJ//.
WATER TABLE





^.
•J'
H
                      IMPERMEABLE
Figure 4-27.
Geometry and  Symbols  of Partially Penetrating,
Partially Perforated  Well  in Unconfined Aquifer
with Gravel Pack  or Developed Zone Around Per-
forated Section   (From Bouwer and Rice,  1976)

-------
    14
    12
 A
AND
 C
    10
                     10
50   100
                                                               LJ J 0
500  1000       5000
        <-e/rw
       Figure 4-28.  Curves Relatinq Coefficients A, B and C to
                         (From Bouwer and Rice,  1976)'.
                        w
                                   4-51

-------
                   In Re/rw
                              ln(H/rw)      L/rw
          Where  C  is  a dimensionless coefficient that is a fraction
          of L/rw.  Using  these equations for deriving the effective
          radius,  Re,  the  authors point out the  calculated values of
          In  Rp/rw are  within 10  percent  of  the actual  value if
          L>0.4H and within 25 percent if LซH.

          The  solution for  hydraulic conductivity  (k)   is  made by
          first  plotting the  recovery of  the water level after  dis-
          placement by a slug (yt)  against  time (t)  on  logarithmic
          and  arithmetic  scales,  respectively.   A straight-line is
          extrapolated  through  the  straight-line portion  of  the
          resulting curve, which  is the  valid part of the readings,
          and  is then  extended to the time  axis.  A point along the
          extended  line  is arbitrarily selected, and then values of
          y.ฃ and t are determined  from  the intersections with  this
          point.   The  term y0 represents the displacement of water,
          in distance, which  is derived from the value at the inter-
          cept  of  the  extrapolated  straight  line with the yt axis.
          After  all  the  terms are identified, the hydraulic conduc-
          tivity (k) can be solved for by the following equation:


                      k = rc2 ln(Re/rw) 1  In y0

                               21       t    yt

          Transmissi vity  (T)   can be solved for by  multiplying the
          hydraulic conductivity  (k)  by the thickness  of  the aquifer
          (D).


Slug  tests  provide a  useful  alternative  to conventional pumping  tests which

are generally  more time-consuming and costly.   However,  the use of slug tests

is limited to  aquifers (or aquitards) with relatively low permeability.


Determination  of  storativity  (S)  from  slug tests  is  not  considered  to be

reliable.   However, transmissivity  and  hydraulic conductivity  can  be deter-

mined with  relatively  high confidence so long as it  is  recognized that these

values are  representative  of the aquifer within extremely  close proximity to

the well.   It  is  also important  to evaluate  other factors  which may signifi-

cantly bias the  test  results with  respect to  this  problem of  limited  test

proximity, such  as:
                                     4-52

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          •  grain  size,   sorting  of  sand  pack  material  installed
             around the screen
          •  ratio  of  the effective volume of  the  borehole annulus
             to the well casing
          •  ratio  of the  volume of the slug to the effective volume
             of the well casing and borehole annulus
          •  well development, i.e., well  efficiency.

These  factors  cannot be  filtered  analytically from  the  results and  should,
therefore,  be  considered  when anomalous results  are  produced.   Nevertheless,
with sufficient  planning, test design  and  interpretation,  slug tests  can  be
utilized to determine aquifer characteristics with relative confidence.

4.3.1.7  Field Permeameter Test
The  field  permeameter  test  is an adaption of  the  basic falling head perme-
ability test.   Water percolates into the formation from  a surface  reservoir,
such as  a  55-gallon  drum.   A sight glass or  pipette  indicates the  flow  of
water, and  measurements,  at intervals, can be used to  determine a  flow rate.
Once  the  flow  rate  has   reached  equilibrium  (indicating  saturation   of  the
surrounding sediments), the value for the constant rate of flow can  be  used in
conjunction with  well  construction  specifications to  calculate  a permeability
value  for the  formation.   The sample  calculation  in Table 4-1 illustrates the
equation and method used to calculate the permeabilities.   Figure 4-29  shows a
typical setup for field permeameter.

4.3.2  Laboratory Tests
The scope of the geotechnical testing program for most ground water  contamina-
tion and waste migration evaluations is generally limited.  In most  instances,
the  variety and number of laboratory  tests performed  is  small.  The  primary
purpose of  the  laboratory testing  program  is  to determine the permeability of
the  soils.    The  testing  program  should  also obtain enough soil  indices  to
allow  for  classification  of   the  project  site soils.   With  sufficient soil
classification  tests,  laboratory permeability  data  can  be extrapolated across
the site.   It should be noted  here that most geotechnical  laboratories are not
equipped  to  handle hazardous  waste  samples  and  some  test methods  require
direct skin contact.
                                     4-53

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                                   TABLE  4-1


                     Sample Field  Permeability Calculation
Field Permeability


K = d2- • In  (2L/D)     t  H-,

    8 • L •  (t2 - i)      Fฃ
    K = Permeability, in./min
    D = Diameter of test hole = 9.0 in.
    d = Diameter of standpipe .= 22.1
        (reservoir diameter = 4 in. and barrel diameter = 22 in,

        (42 = 222)^ = 22.4 in.)
    L = Length of test hole = 62.0 in.
    HI = Piezometric head at time = t^

    \\2 = Piezometric head at time = tฃ

    K = (22. 4)2 In (2 x 62/9) In 13.60 = 5.8 x 10'3
                8 x 62 x 50      12.23

      = 5.8 x 10'3 in./min = 2.4 10"4 cm/sec
                                     4-54

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22" diameter
55 Gallon Barrel
                                                     Siphon Hose
                                                     2' Long *Sightglass'
                                                    4" diameter Reservoir Pipe
                                                    Concrete Plug
                                                     2" diameter Riser Pipe
                                                    Native Soil Backfill
                                                     Granular Bentonite
                                                     2" X 5' Slotted Well Screen
                                                         C0.008" Slots)
                                                     No.2 Blast Sand
                                                     TO
        Figure  4- 29.  Field  Permeater  Installation

                             4-55

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4.3.2.1  Index Tests
The following table  lists  common  soil  index  and  classification  tests  with the
corresponding ASTM  test method.  Although  there are other test methods, for
the purpose of this discussion only ASTM test methods are referenced.
    INDEX/CLASSIFICATION TEST
    Test Method for Liquid Limit,
    Plastic Limit, and Plasticity
    Index of Soils
    Method for Laboratory
    Determination of Water
    (Moisture) Content of
    Soil, Rock, and Soil-
    Aggregate Mixtures
    Method for Particle-Size
    Analysis of Soils
    Test Method for Amount of
    Material in Soils Finer
    Than the No. 200 (75-uM)
    Sieve
COMMON USAGE
Atterberg limits
Moisture Content
Gradation Analysis
Minus 200
ASTM TEST METHOD
    D 4318-84
    D 2216-80
    D 422-63
    D 1140-54
A  visual  inspection  of  the soil  sample  can help  to  determine which  index/
classification  tests  to perform.   In general,  fine-grained materials  (i.e.,
clay  and  silts)  are  classified according  to plasticity, and  coarse-grained
materials (i.e.,  sands and  gravels)  are classified  by  gradation.   If the soil
sample  is  a clay, or  primarily  clayey or silty in composition, an  Atterberg
limit test  and  minus  200 mesh-sieve  test  will be  sufficient  in most  instances
to classify the sample.    The  natural moisture  content will be  determined  in
the Atterberg  limit  test.    However,  if  the  soil sample  contains  appreciable
material  of various  particle sizes,  or  is  primarily sandy  or gravelly  in
composition, a  complete  gradation analysis  (includes  No.  200  sieve) will  be
required for proper classification of the  sample.   In  these  cases,  a separate
natural moisture  content  test will  need  to  be  performed.   As most  soils are
composed of materials with  differing  particle  sizes,   judgement needs  to  be
exercised in the  selection  of  index/classification  tests.   In  instances  where
there is a  question  about which tests to  select, an Atterberg  limit test and
complete gradation analysis  should be performed.
                                     4-56

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For projects  involving construction of new facilities,  additional  laboratory
testing will  be  required  to  provide  the necessary  geotechnical  design  parame-
ters.   Additional  testing might include compaction, shear strength, and  con-
solidation tests.  This discussion will be limited  to the index/classification
and permeability tests generally associated with initial  ground  water investi-
gations.

Atterberg Limits
Atterberg  limits were first  developed in 1911  by a Swedish soil  scientist,
Albert  Atterberg,  for the  purpose of evaluating  plasticity  of soils.   From
Atterberg1s original  work, three  sets  of  limits  were adopted  for  use in foun-
dation engineering.

          NAME OF LIMIT                     SOIL CONSISTENCY
          Liquid limit                      fluid
          Plastic limit                     plastic
          Shrinkage limit                   semi-solid to solid

Natural soil  moisture  content is normally  between the liquid  limit and  shrink-
age  limit;  however,  many soils are  in the more  restrictive range between the
liquid and plastic limits.

The  original  limits  were  qualitative  and, later,  Terzaghi  (1926,  1927)  and
Casagrande  (1932)  arbitrarily quantified  the plastic limit and  liquid limit,
respectively  (Figure  4-30).   In recent years,  the Atterberg limit test has
been  used as one  indication of  the suitability of soils for  waste disposal
sites.  Both  TWC and TDH have established  guidelines for Atterberg limits.

Standard  specifications, such as ASTM D4318-84, are available  for standarizing
preparation of  the  soil  sample for  the Atterberg  limit  test.   Details of the
standard  specifications  will  not be  presented;  however, a  critique   of the
standard  procedures will  be presented.  (It should  be  noted  that ASTM D2217-
66, Procedure B, presents a wet  preparation method  which avoids  the problems
associated with  ASTM D4318-84).

The Atterberg limit test  is  performed on the soil  fraction  which passes the
No.  40 sieve.   Thereafter,  to  facilitate  sieving  the  soil,  some  standard

                                     4-57

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methods  (i.e.,  dry preparation)  recommend drying  the  soil  prior to  sieving.
The  air- or  oven-dried  soil  is then  pulverized using  a  mortar and  rubber-
tipped pestle.   Several  problems which  exist  with this method  are  discussed
below.

Large reductions may occur  in the liquid  limit  as  a result  of  oven  drying  and
somewhat smaller changes occur in the  plastic  limit.   As the  plasticity index
is the  numerical  difference between the  liquid limit  and plastic  limit,  the
plasticity  index  may decrease by  a rather large  amount.   Data published  by
Eden  (1959)  on a  wider  range  in soil types  indicated an increase  in  liquid
limit of some shales upon air drying and  a decrease on  oven  drying.   It may be
that  air drying produces  a more thorough breakdown of  the structure  of  the
shales.   Oven drying apparently resulted  in  irreversible dehydration  of  the
shale.

If the soil is dried prior to performing  the  Atterberg  limit,  it may take some
time for the  soil  to rehydrate.   Generally, as the  "tempering  time"  increases,
the  liquid  limit  will  decrease until  finally leveling  off  at  a  constant
value.   For most plastic clays,  the tempering time  may  take  up to 16 hours.

Air drying  or oven drying tends to make  highly plastic  soils  extremely hard.
Therefore, when an overall soil  sample is pulverized, the less plastic materi-
al breaks  down  first.   As  pulverizing the soil  by  hand  is  difficult,  as soon
as sufficient material  has been ground  past  the No. 40 sieve,  the  test will
proceed.   Because  the  less plastic material  breaks  down  last,  it tends to be
selected out  of the sample.

As can be  seen  from  the  above discussions, the results of the Atterberg-1imit
tests  are  dependent upon  test  methods  and  the techniques of  the  operators.
Therefore,  test results can  vary  considerably  between  testing laboratories.
It should also"be  noted that due to the high  degree of  disturbance  inherent in
Atterberg  limit testing,   in  situ  physical  properties  of  the soil   may  be
different.  Atterberg  limits  are,  however, a good  indicator  of soil physical
properties.
                                     4-59

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4.3.2.2  Permeability Tests
As discussed  in Section  1.2,  flow  in saturated soils is governed  by  Darcy's
Law:

          q = kiA

where:
          q = rate of flow
          k = hydraulic conductivity
          i = Ahi = hydraulic gradient
              AL
             Ah = difference in heads at the two ends of soil sample
             AL = length of soil sample in direction of flow
          A = total cross-sectional area of soil sample

Theoretically,  Darcy's  Law  says that  seepage  is proportional to the hydraulic
gradient  for  a unit  area  with the constant of  proportionality  being  the hy-
draulic conductivity  (coefficient of permeability).

The hydraulic  conductivity  for a given soil  is dependent upon a large number
of variables  such  as particle size, grain  size distribution and orientation,
and density.    The  best  way  to determine  the permeability of  a  soil  is by
conducting the  permeability test on a soil sample having:

          1. The same particle size,
          2. The same void ratio,
          3. The same composition,
          4. The same structural arrangement of particles,  and
          5. The same degree of saturation.

While it is impossible  to reconstruct conditions in the laboratory which match
all the  conditions of  the  in situ natural  soil,  use of a  relatively undis-
turbed soil  sample  in  the permeability  test  is a  step in the right direc-
tion.   Obtaining an  undisturbed  sample  which is representative of the in  situ
soil  conditions is in itself very difficult.

Measurement  of  the  permeability  of the  soil  is done by constructing a  test
arrangement which measures a flow rate through a soil sample of  a known degree
                                     4-60

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of saturation  under a  known hydraulic gradient.   The coefficient of  perme-
ability  (k)  is then  back-calculated  from these measurements.   Two  standard
test methods,  the constant  head  test  and  the  falling  head  test,  are  typically
utilized in conducting the permeability tests.

In the constant head test,  the  hydraulic  gradient  is  maintained  at a constant
value throughout the test, and a total volume  of flow, q,  is measured during a
time period, t.  The problem with the constant head test is that  at low values
of head  in fine-grained  soils,  the  volume of  flow  may be so small that  it
becomes difficult to reliably measure.

Usually, for fine-grained  soils, a falling head test  method  is  used  in which
the change in  head in a volumetric tube is measured for a time period, t.  The
volumetric tube will have a small cross sectional area; therefore,  a relative-
ly small  change  in  volume  and  flow  quantity  will   result  in a  significant
change in the  position of the water level  in the tube.  Even in a falling head
test, the testing time may become lengthy  under small  heads.  The testing time
may  be  increased  by superimposing  an air pressure on  top of the water thus
increasing the hydraulic  gradient.   Figures 4-31  and  4-32 show  a  permeameter
cell and pressure board for performing permeability tests.

A  state-of-the-art  paper written  by  01 sen and  Daniel (1979) presents  a  de-
tailed discussion  of the effects  of  various  test procedures  on the measured
value of the coefficient  of permeability.   Material for the following discus-
sion comes primarily from this reference.

As indicated previously, it is difficult to obtain an  undisturbed sample which
is representative  of the  mass   in  situ soil  conditions.   The field  sampling
process  typically  imparts   a major  degree  of disturbance   as  does  sample
handling  in  the laboratory.   Unrepresentative  sampling and  sample  selection
represents the  largest  source of error in laboratory  tests.   Natural, in situ
soil  characteristics  such as fissures, roots,  sand  lenses,  etc., which con-
tribute  greatly  to the  overall  mass permeability   characteristics of  the
strata, also cause  the  most difficulty in  sample  preparation for  the labora-
tory tests.   The  least  difficult samples  to  prepare  are the  intact, cohesive
samples, which are  also the most impervious.    In  the setting of a commercial
                                     4-61

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                                          Quick-Connect
Top Plata
 Clamping
     Rod
 Baaa Lag
  Flow Out to Call
  Praaaura Board
                                                                 Call Wall
Flow Out
Pluggad
                     Figure  4-31.  Permeameter  Cell
                                      4-62

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   PRESSURE BOARD
To Cell Pressure Port
or Cell Flow-In Port
or Cell Flow-out  Port
Figure 4-32.   Pressure Board.
                                            To Pressure
                                              Regulator
             4-63

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testing laboratory, the tendency to select the  "easiest"  sample  to  trim tends
to selectively  limit  the testing to  the  impervious  samples.   In addition  to
the  selectivity  of lab  testing,  other errors  introduced in  the sample  pro-
cedure are:

          1. Voids created at the sides of the samples,  and
          2. Smear zones created on the face  of the sample.

Changes in  laboratory permeability can occur  with  differences  in the  permeant
which is used.   The use  of  distilled  water can alter the pore  water chemistry
of  clay samples,  resulting  in induced  swelling and  reduced  permeability.
Figure 4-33  indicates  the effect of distilled water.   The most  reliable  test
results can be  achieved  by  permeating  either the  natural  ground  water,  or
representative samples  of the expected waste  liquid through  the sample.   If
these alternatives prove to be impractical, then tap  water should be utilized.

As  the  test  methods  presented  in  this  discussion  address  saturated  sample
conditions,  the  presence  of air in the sample can have  an effect on  the  test
results.  Air bubbles in the sample effectively reduce the void space that can
be occupied  by water and  thus reduce  permeability.   As  air bubbles  are pushed
out of the sample, the permeability can increase significantly.

An  increased hydraulic  gradient  to  decrease  testing  times  can affect  some
samples.   Although theoretically,  the coefficient of permeability  is  a  con-
stant, some  researchers have  found that k increased  as  the gradient increased
(Schwartzerdruber, 1963).

Many  laboratory  test  results  are corrected  to  a   standard  temperature  to
account for  viscosity  changes in  the pore fluid.   The  effect of temperature
can be seen  in Figure 4-34.  For the typical  range in temperatures expected in
a normal laboratory or field setting,  this correction is not  absolutely neces-
sary.

The orientation  of the sample can significantly  affect  the test result.   The
in situ horizontal permeability, kh,  will, in many cases, be  much higher than
the vertical  permeability,  kv.  Measurement  of horizontal permeabilities can
be very difficult, therefore, most laboratories measure only  kv.

                                     4-64

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 o
 0)
 E
 o
 03
 (D
 E
 i_
 CD
CL
                     Permeant: Distilled  Water
                     Sample  No. 2
Permeant ••
    Natural  Pore  Water
Sample  No. 7
                 20     40      60      80
                 Cumulative  Inflow,  cc
                       100
           Figure 4-33. Influence of Using Distilled  Water
                      (From Wilkinson, 1969)
                          4-65

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 KT=21ฐ
           0
            20
                      KEY
                 •  Taylor Marl

                -t-  Kaolini te

                *  Tokyo Silt


                 Relationship   Predicted
                 by Viscosity  Correction
                                Average   Measured
                                Curve
                                              _L
           30         40         50

             Temperature  (ฐC)
60
Figure 4-34 .
Effect of Temperature on Permeability.  Permeabilities
at temperature t  (Kj) are normalized with respect to
the measured permeability at 25ฐC.  (Colson & Daniel,
1979)
                            4-66

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At best,  laboratory test  results  are qualitative  indicators  of soil  perme-
ability.  Provided  reasonable test procedures are followed,  the  typical  labo-
ratory  tests  will  indicate  the  order of magnitude  of  the permeability.   As
typical  soil  waste  migration  rates   are  small  magnitudes  to  begin with,  an
order of magnitude  accuracy  in the laboratory test  results is  normally suffi-
cient  for  prediction  of  migration  rates to  a  suitable  accuracy.   If  field
investigations reveal  that  a site  is located in unconsolidated,  sandy depos-
its,   then  laboratory  permeability testing  should  be supplemented  with  field
permeability testing.
                                     4-67

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5.0  HEALTH AND SAFETY WITH RESPECT TO GROUND WATER INVESTIGATIONS

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      5.0  HEALTH AND SAFETY WITH RESPECT TO GROUND WATER INVESTIGATIONS

A fundamental  policy of all  ground  water contamination investigations  is  to
provide a safe and healthful work environment for all  personnel  involved.

It is both a moral obligation and sound business practice to prevent accidents
(in  that  accidents  can cause  personal  injuries  or  illnesses  and  property
damage).   No phase  of  operations  or administration should be of  greater im-
portance  than  injury and illness  prevention.   Safety should take  precedence
over expendiency  or short  cuts.   Every attempt should be made to  reduce the
possibility  of  accident occurrence.    Safety,  good industrial  hygiene  prac-
tices,  and   loss  prevention are the  direct responsibility  of  all  levels  of
management.

The statements above express a general attitude towards Health and  Safety that
should  be implemented  by  all  personnel  involved  in  ground  water  investiga-
tions.  The  issue  of Health and  Safety should  be taken much further than this
general concept.   Detailed, job-specific, Health  and  Safety  procedural  plans
should be devised for all major undertakings.

Inherent  problems arise from the requirement of job-specific Health and Safety
plans.  There  is often little site-specific information available,  and plans
are frequently written  which  are too  complex for the  site  being  studied.  The
following discussion is presented  to illustrate the need  for good Health and
Safety programs  as  well  as  discuss  some of the problems created  by Health and
Safety plans.

5.1  JOB-SPECIFIC HEALTH AND SAFETY PLANS
Job-specific  Health and  Safety  plans  generally  include discussions  on both
universal safety practices  as well  as specific job-related  practices.  Several
items are briefly described below as they relate to field investigations.

5.1.1  Assignment of Responsibilities
Specific  duties and  responsibilities are designated to the  individuals direct-
ly involved  in the  job.  Generally, a Health and Safety Supervisor is directly
involved  in  writing the Health  and  Safety plan prior to  job start-up and is
                                      5-1

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on-site  during  job  start-up  and  during critical  functions through  comple-
tion.  Enforcement of all other daily on-site Health and Safety  procedures are
the responsibility  of  assigned field  personnel  including  Technicians,  Project
and Site Managers and Field Engineers/Scientists.   Normally,  Health and Safety
specialists are  not utilized in areas where the  staff  is  fully  familiar with
the site and its potential hazards.

5.1.2  Employee  Training and Information
Personnel directly  involved in potentially hazardous on-site  activities should
be required to complete  some  approved  form  of  site specific  Health and Safety
training.   Site-specific  training  and  information  generally includes  about
four hours of  safety training  conducted  in  the  field by the  Health and Safety
Supervisor  at  the  beginning  of  the  job.   In  addition, abbreviated  safety
meetings (tailgate  safety meetings) are  then conducted  by the appointed field
safety supervisor prior  to the beginning of (each days)  activities.  Figure 5-
1 is a  typical form used to  record safety meeting participation.  All  persons
involved in  hazardous  waste work  should  also  have completed a  minimum  of 40
hours of non-site  specific Health and Safety training  and should be enrolled
in a medical monitoring  program.

5.1.3  Employee  Decontamination
Generally,   on-site  decontamination  facilities  will include  decontamination
line  facilities  consisting  of separate  wash  tubs  for  hands,  face and boot
cleansing,  waste containers  for soiled tyveks  and gloves, and  a storage area
for equipment.   Emergency eye wash/shower facilities are  sometimes  set up at
small sites but  at  those sites where  the potential contamination is low, they
are not usually  utilized.

5.1.4  Personal  Protective Equipment and Procedures
When working in  hazardous or potentially hazardous areas, the minimum required
equipment  includes  disposable tyveks, protective  gloves,  and safety glasses.
Where working around heavy equipment, hard hats and protective steel toe boots
are  also  necessary.    When  atmospheric  exposure  levels exceed  recommended
breathing  levels,  respiratory  protection  is  required.   Respiratory protection
is provided  primarily through the use  of  half-face or  full-face  forced air
respirators  with applicable  filter  cartridges.    "Positive-pressure"  filter
                                      5-2

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Division/Subsidiary
Date	
Customer
Specific Location
Type of Work 	
Chemicals Used
                 Facility
Time_
Job Number
                -Address:.
Protective Clothing/Equipment.
                                   SAFETY TOPICS PRESENTED
Chemical Hazards-
Physical Hazards-
Emergency Procedures.
Hospital / Clinic 	
Hospital Address	
Special Equipment
        Phone (
Paramedic Phone (    )
Other
                                            ATTENDEES
                    NAME PRINTED
Meeting conducted by:
Supervisor
                      NAME PRINTED
                                   SIGNATURE
                                                                      SIGNATURE
                    Manager.
                         Figure  5-1.   Tailgate Safety Meeting Form
                                                5-3

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respirators such  as  the  RACAL units are also used.   Although  less  frequently
needed, the use of  self-contained breathing apparatus can  also  be  required if
exposure levels are excessive.

5.1.5  Regulated Areas
To prevent the spread of contamination and  limit personal  exposure,  potential-
ly hazardous ground water investigation sites  are generally divided  into three
delineated zones.

          1.  Contaminated  Zone  -  This  zone  includes  the  actual
              areas  of  contamination  and has the highest potential
              for contaminant exposure.
          2.  Contamination Reduction  Zone  -  This zone  includes the
              areas   immediately   surrounding    the   Contamination
              Zone.   It  is  in  this  area   that  the decontamination
              facilities are installed.
          3.  Clean  Zone  -  This zone  covers all area outside of the
              contamination reduction zone.

5.2  GENERAL WORK PRACTICES
Safe and healthy  work practices are extremely important  during  field  investi-
gations.  Through past experiences  and  training,  the  personnel  designated for
field  activities  should   become  very  familiar with  general  safe and  healthy
work practices.

5.2.1  Personal and Ambient Air Monitoring
Air monitoring  equipment  generally  used on-site  includes  such  devices  as the
HMD photoionization meter, draeger tubes, and  explosimeter.  The HNU is usual-
ly the  primary  means for determining atmospheric  exposure  to  on-site  organic
contaminants.  HNU readings are recorded periodically during field  activities,
generally by the Field Engineer/Scientist.

5.2.2  Emergency Procedures
A general description of supplemental  emergency  response procedures is  usually
included in the Health and  Safety plan.  Procedures are outlined for specific
situations  such  as  fires, spills,  worker  injury, etc.    Emergency  procedures
are discussed  in  the field  prior  to  job start-up.   Emergency  phone  numbers,
hospital locations, first aid kits,  fire extinguishers and other safety equip-

                                      5-4

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ment are obtained and located in a readily accessible location.   Figure 5-2 is
a typical form posted at locations where site work is in progress.

5.3  PROBLEMS ASSOCIATED WITH HEALTH AND SAFETY PROGRAMS
The following section discusses  some of  the  problems that  seem  to  be inherent
to  the  process  of  writing a  Health  and Safety  plan which  is  realistically
implementable in the field.

A major  problem  associated with Health and  Safety plans is  the  fact that the
plan writer's perspective  is  different  from  the perspective  of  the  people
involved  in  job  plan implementation.   Each  year clients place  more and  more
emphasis on  a potential  contractors Health and  Safety program as a measure of
the  companies qualification  for  certain  jobs.   In  addition  to  this,  many
companies' Health  and  Safety programs have  become very  "liability"  oriented.
This increased "political"  attention and  liability concern  has  resulted in an
attempt  by  Health and  Safety  plan writers   to  become as thorough  and  as de-
tailed as possible,  attempting  to  address and  provide procedural requirements
for every possible  health  and safety hazard that may be encountered on-site.
Theoretically this is fine, however, in reality what  frequently happens is the
Health and Safety  plan  becomes  so rigid, time  consuming,  costly,  and compli-
cated that it can no longer be effectively implemented in the field.

Field personnel  generally  do not  posses  the "political" or  "liability"  per-
spective  towards the Health and Safety  issue.   These people are  simply  con-
cerned with  getting  the job done  safely  and efficiently.   As stated earlier,
the  people  designated  for  field work  should  be Health and  Safety  qualified
through  experience  and  training.   In  addition to   enforcement  of prescribed
Health  and   Safety   procedures,  decisions concerning day  to day activities
should also  be  the responsibility of the field personnel.   Health and Safety
plans  should be  written to  provide  Health and  Safety procedures  for known
and/or expected  hazards  but  should  also  allow  for easy amendment  by qualified
field supervisors.

A  second problem  occurring with  respect to  job-specific  Health  and  Safety
programs  is  one  of  insufficient  time.   Generally,  a  somewhat "generic" Health
and Safety plan  is drawn up and submitted with the  work plan when a job pro-
                                      5-5

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            EMERGENCY NUMBERS
Ambulance...	
Doctor...	
Hospital[[[
Fire Dept.........................................	...........!................
Police	......................................'...................................
Sheriff	
U.S. EPA (24 Hour Hotline) ........800-424-8802
Chemtrec.	......................800-424-9300
National Poison
Control Center	404-588-4400




	UTILITY NUMBERS	

Electric Co	...........
Water Co	'......	
Gas Co	

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posal  is  written.   A more detailed,  job-specific  Health  and Safety  plan  is
written up only  after the  job  has  been secured.   This often creates a problem
with  respect  to devising  a  complete,  job-specific  Health  and  Safety  plan
before the work  begins.  For this reason, Health  and Safety plans  often become
"cut and  paste"  versions of plans previously written  for  other jobs.   Admit-
tedly, there is  abundant "general" health and safety information  and even some
job-specific  information that  can  be  transferred  from  one job  to  the  next,
however, unnecessary  procedures often  end up  being  transferred.   Once entered
into the  Health  and  Safety plan,  it  is then the  burden of  the field personnel
to implement them.

The final problem discussed here is the fact that often the people involved in
writing the  Health  and Safety  plan  have  very little knowledge of  actual  field
operations.   Many  times procedures  are outlined  in  Health and  Safety  plans
that  unnecessarily  hinder field  activities and   can  even create  dangerous
situations.   An example of  this  can be taken from a health  and  safety plan
that required  all  personnel  involved in field activities  to  wear goggles for
eye  protection  rather  than regular OSHA  approved safety glasses.   Goggles
restrict  vision  more  than  regular  safety glasses  and  fog up easily during hot
weather.  There  may  not have been  a hazard  at the site that justified the use
of goggles instead of  safety glasses, yet the difference between  a full day in
goggles compared to a full day in  glasses  in enormous.  Obviously the person
writing  the  plan had not spent many  days  drilling  in  95 degree  weather in
goggles.  Again, to  prevent  problems such as these from occurring, Health and
Safety  plans should  be  written  in  such a  manner  as to  address  and  provide
information  and procedures  for  any known  and/or  expected  hazards,  but the
responsibility  of  day to day health and safety  decisions  should  be placed on
qualified field  supervisors.
                                      5-7

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6.0  SAMPLE INTEGRITY

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                             6.0  SAMPLE  INTEGRITY


The  integrity  of  samples  collected  for the  purpose of chemical  analysis is

extremely  important  to the  validity  of the  analysis obtained.   When proper

procedures  are  followed during sampling,  storing  and transporting of samples,

their  integrity can  be  preserved.   This  section  discusses  procedures  that

should be followed during these events.


6.1  SAMPLE COLLECTION AND HANDLING


6.1.1  Decontamination and Sampling Procedures for Soils

The  prevention  of cross-contamination  between  samples is of  critical  impor-

tance during soil  sampling  operations.   The sampling procedures followed must

allow samples to be collected without coming into contact with outside contam-

inant sources.   Recommended decontamination and sampling  procedures are dis-

cussed below:

          1.  Prior  to drilling,  all  drilling equipment  should  be
              checked  for  possible contaminant sources  such  as  oil
              or grease  leaks,  hydraulic fluid line  leaks,  and  pos-
              sible air compressor oil  emissions.  Any problem areas
              should be repaired.

          2.  Prior to drilling, all equipment  including drill  bits,
              drill rods, augers,  hand  tools,  and  sampling equipment
              should be cleaned, preferably with a high temperature,
              high  pressure  soapy  water,  then   rinsed   with  high
              temperature,  high  pressure  clean water.  In addition,
              all  sampling  equipment should  be rinsed successively
              with distilled  water,  methanol  or hexane, and  finally
              with distilled  water or  deionized water again.   Alter-
              nate methods  may  be required  based  on site-specific
              conditions.

          3.  After  cleaning,   all  sampling   equipment   should  be
              stored  in  a  clean area  to  reduce  the  possibility  of
              contamination  prior  to use.   All decontaminated  sam-
              pling equipment  should  be handled in  such a manner as
              to preserve  cleanliness  (i.e.,  don't  handle equipment
              while wearing  gloves used to change  drill  rig  oil  or
              add  hydraulic fluid, etc.).

          4.  After  obtaining a sample,  the   sample  should be  ex-
              truded  from  the sampling device  into  a sample collec-
              tion tray  with minimal  handling.  Personnel  handling
              the  samples  should wear  clean,  disposable gloves  such


                                     6-1

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              as  latex  surgical  gloves.    Job-specific  analytical
              requirements  may  not  necessitate replacement  of the
              disposable  gloves  between  each  sample  collected   to
              minimize possible cross-contamination between samples,
              however,  it  is a good practice.   As  a  minimum, the
              gloves should be changed between drill locations.

          5.  Select  portions  of the  sample should  be  retained  in
              containers  compatible  with   the  intended  analysis.
              Site  specific  requirements  may necessitate  the use  of
              teflon  lined  lids and/or other preservative measures
              and the  samples should be collected in  accordance with
              these  requirements.   The  sample jars  should  be ade-
              quately  marked for  identification at  the time of col-
              lection.  Marking should be on a  tag  or label attached
              to the  sample  container  and should include as a mini-
              mum:

              •  Project name and number

              •  Unique sample number

              •  Sample  location  (e.g.,  boring,  depth  or sampling
                 interval, and field coordinates)

              •  Sampling date

                 Individual performing the sampling

              •  Preservation or conditioning employed

          6.  After  sample  collection,  the  used  sample tubes, col-
              lection  trays  and other  sampling equipment should  be
              stored  in  a  separate  area  prior  to reuse until  decon-
              tamination has been performed.


In  some  investigations, such elaborate  decontamination may not  be required.

For  instance,  samples collected  in  Shelby  tubes are approximately 18 inches
long by 2  inches  diameter.   If  the  sample was collected in a "dirty" sampling

tube only  the  outside edges of the  core  would  be  "dirty"  or potentially con-

taminated.  The outside  areas could  be  cut  or trimmed off.  In addition, such

tools as  cork  borers  can  be  utilized  to obtain samples from  the  interior of

the  core.   In any  event,  field investigators  should take  care in collecting

samples to prevent cross contamination.
                                      6-2

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6.1.2  Collection of Ground Water Samples
The importance  of  proper sampling of monitor wells cannot  be  overemphasized.
Even though  the well  being sampled may  be correctly  located and  constructed,
precautions  must  be taken to ensure  that  the  sample  taken from  that  well  is
representative  of  the ground water  at that location  and  that the  sample  is
neither altered nor contaminated by the sampling and handling  procedure.

6.1.2.1  Static Water Level Measurements
A static water  level  should be taken  in each well  prior to evacuation.   This
data is necessary to construct piezometric surfaces to determine the direction
of ground  water flow at a given  time.   The  accuracy  and precision  with  which
these  measurements  are  taken are dependent upon  the hydrology  of  the  site.
Those  areas  with relatively  horizontal  piezometric surfaces demand  more  accu-
rate and  precise measurements.    Detailed  records  of  the  time  and  conditions
during  measurement  are  necessary  due to  potential environmental influences.
Tides  (in  coastal  areas),  barometric pressure, and highway or  railroad  traf-
fic, among others, can cause measurable differences in water levels.  In  areas
of  low hydraulic  gradients,  these differences can  result  in projecting  wrong
directions  of flow.   Tapes  or  carpenter's  rules  capable   of measuring  accu-
rately  to  0.01  foot  should  be  used.   Values  should  be read  in  a  consistent
manner  off  of electric lines (E-lines).   For  instance,  depths  should consis-
tently  be  taken from the bottom  of  the  lowest  colored band on  the  Olympic  E-
line during  the first event  (if they were  measured  from  this point  on).   A
surveyed mark or groove  at the top of the casing should be  used as a reference
point  to  eliminate  errors due  to unevenly cut  casing tops.    Finally,  the
measurement  should  be  taken more than  once while at the well  to determine
reproducibility.   In areas with  high gradients,  ascertaining  reproducibility
and noting possible influences is not as critical.

Decontamination  of  E-lines  between  wells may  not be necessary because  the
minute  amount of contaminant introduced  into the well   should be removed during
purging.  However,  they  should be wiped off with disposal towels dampened with
distilled water.   If  the water  level probe is coated  with  visible residue,  it
should  be  sufficiently  cleaned  to remove the visible  contamination.  This may
include using a non-phospate  detergent or  an  organic solvent followed  by a
rinsing of distilled water.  The TEGD  suggests a more  thorough decontamination
                                      6-3

-------
procedure.   In  order  to  further  minimize the  transmission of  contaminants
between  wells,  measurements  can  be  taken in  the  least  contaminated  wells
first.

E-lines are also used to sound the bottom of the wells,  primarily to determine
if silting has occurred which may  influence the  thickness of  the unit yielding
water to the well.  Enough weight  should be on the probe at bottom to keep the
line  vertical.   Olympic E-lines have weights that  can  be added  to  the  probe
for this purpose.  Brainard-Kilman well  probes are heavy enough  that they hang
plumb.   Where dedicated  permanent  pumps  have  been installed,   sounding  well
bottoms  with  E-lines may  not be  prudent.   The  time and effort  required  to
remove  the  pump  is  not  warranted in all  cases.    Instead,  careful  attention
should  be  paid to the turbidity of  the  water purged from the  wells  prior  to
sampling.  If  turbidity is increasing compared to earlier sampling events, the
removal of the pump may be called  for to confirm that the well  is silting up.

6.1.2.2  Detection of Immiscible Layers
Immiscible  ''ayers  are  those  with densities  less than or  greater than ground
water.   RCRA  suggests that  testing  for immiscible layers be included  as the
initial step in  any water sampling plan.

For "floating" immiscible layers to be intercepted and detected  in a well, the
well screen must extend above the  top of the ground water and into the zone of
the aquifer containing the  immiscible layers.   To capture sinking layers, the
screen must extend  into the  aquitard.   It  should be remembered  that the slots
on most PVC screens begin 6 inches from  the end  of each  joint.   Care should be
taken in well  construction so that the slots actually intersect  the horizon of
interest.

Hydrocarbon indicating paste  on an E-line can be used to measure the thickness
of  a  floating  immiscible layer.  An  interface  probe may also  be used  if the
well  is  accessible for the  larger  probe.   If a  permanent pump is installed,
there may  not  be a large enough port on the  well cover to  allow access.  In
addition,  there   is  probably  not  enough  clearance  around  the pump  to  take
readings on sinking layers.
                                      6-4

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If an immiscible  layer  is  detected,  a  sample  should  be  taken for analysis.   A
top-filling bailer  or  sampling  device  is the easiest method  for collecting  a
floating layer.  A  bottom filling bailer can be  used  to  sample a sinking  layer
provided the  well  is not completed with a  permanent  submersible pump  or suf-
ficient  room  exists to allow  the  bailer   to pass.   In  areas  where  sinking
immiscible  fluids  are  suspected,  a sample  can be collected  within  a few min-
utes  of  turning on the submersible pump is  the  submersible pump  is  located
near the bottom of  the well.

6.1.2.3  Well Purging
The purpose of well purging is to eliminate  stagnant  water in the wellbore and
adjacent sand pack  which may have undergone  chemical  alteration, thus  allowing
the collection  of  a sample that  is  representative  of the in  situ  quality  of
ground water near a particular well.

Various methods for determining the necessary extent  of  well  purging have been
recommended.  The U.S.  Geologic Survey (USGS)  has  recommended pumping  the well
until  temperature,   pH  and specific  conductance  are constant  (USGS,  1976).
Schuller and  others recommend calculation of  the  percent  aquifer water pumped
versus time based upon drawdown in the well  (Schuller, 1981).  The Environmen-
tal Protection  Agency  (EPA) recommends  removal of  three well  casing  volumes
prior to sampling.

The extent  of  well purging will  vary with the  hydraulic  properties of the
water-bearing unit  being monitored.  Without  proper  consideration of  the flow
characteristics of  the  monitored  unit, the  integrity of  the sample collected
after  purging could be compromised.   Giddings  indicates  that  emptying the
wellbore of  a well  screened in a  low  yield unconsolidated  aquifer can result
in a  steep  hydraulic gradient in the  sand  pack (Giddings,  1984).   This  steep
hydraulic gradient, in turn,  can  lead  to the addition  of clays  and  silts  to
the produced water, turbulent flow into the  well,  and with turbulent flow into
the well, a possible loss of volatile organics in the  produced water.  Simi-
larly, wells screened in very low-yield bedrock  with  fracture flow may also be
bailed dry.   If the water-bearing  fractures  or higher permeable  zone is lo-
cated near the static water table, the water will  refill the well by cascading
into  the  wellbore,  which will  result  in the loss of volatile compounds from
the water.
                                     6-5

-------
Purging of a  high yield  aquifer that  has major water-producing  fractures  or a
highly permeable unit at the bottom of a screened  section  in  an  unconsolidated
aquifer may result  in  limited purging of water higher  up  in  the wellbore  and,
in the  case  that any  monitored species  has  a specific gravity  less than  the
formation water,  it is  likely that it  will  be  detected at  "lower  levels  than
exist in the aquifer.

Removal of  stagnant water from the well bore  before sampling is necessary to
ensure that a representative  sample  is  obtained.    However,  equally  important
are the hydraulic processes resulting  from  well  purging.   In  order  to minimize
turbulent flow and sample alteration,  it is recommended that, prior to  prepar-
ing a sampling program, each monitor well  be  tested  to  determine the  necessary
extent and the  appropriate rate of well purging.  Determination of the neces-
sary extent of well purging can  be based  upon equilibration of ground water
indicator parameters during well evacuation.  Figure 6-1  indicates changes in
nine analytical  parameters  with  pumping in a well  that had  been idle  for six
months  prior  to  pumping.   When  pumping began,  the  partially  reduced water
surrounding the  pump was discharged  first.   As  pumping  continued,  formation
waters were drawn  into the wellbore and the  rate of change  in  the concentra-
tion of the chemical parameters decreased.  Because of the low discharge  rate
of this well,  the  mixing of wellbore  water and formation  water continued for
45 minutes  (Chapin, 1981).  In  order to obtain a  representative  sample,  the
QA/QC sampling  protocol  for  this  well would  specify a minimum  period  of  well
evacuation of 45 minutes  prior to collection  of  the  sample  when  using  the
existing pump run at the same flow rate  used  in the  test.

6.1.2.4  Sampling Devices
Commonly used  sampling  devices  include  electrical submersible  pumps, positive
displacement  bladder pumps, bailers and suction  lift   pumps.   Choosing a  sam-
pling device  is  dependent  upon  site-specific  criteria  including compatibility
of the rate of well purging with well  yield,  well  diameter, limitations in the
lift capability of  the device, and  the  sensitivity  of   selected  monitoring
species to the mechanism of sampling delivery.

It is important  to  recognize that  aeration or degassing of a sample can occur
during withdrawal  of a  sample  from a  monitoring well.    The  introduction or
                                     6-6

-------
                          30     45
                         TIME CMINUTES)
70
                                                 (Chap-in, 1981)
Figure 6-1.   Concentrations of Chemical Parameters vs.  Pumping  Time
                             6-7

-------
loss of  volatile organic  compounds  or gases  (02,  ^ CC^,  and CH4)  in  the
ground water sample  can  affect the  ground water  solution  chemistry  of  the
sample,  and  result  in  the further speciation  of  both volatile organics  and
other  analyses  of interest.   The  degree  of aeration and/or degassing  of  the
ground water has been shown to vary with the type of sampling device employed.

A  field  evaluation  of sampling  devices was  conducted  in  association  with
ongoing  remedial  action at  the  Savannah River  Plant,  Aiken, South  Carolina
(Muska,  et al.,  1986).  The electric submersible pump was  chosen over various
modified bailers,  the bladder pump,  and others because of its  accuracy,  pre-
cision,  reliability,  its  ability to evacuate  a well, and its moderate cost.
However, levels  of organics  at  the  Savannah River Plant range  up  to 200,000
ppb.   In this  case,  detection of organics  near analytical  detection limits (1
to 10  ppb)  was not a  criteria for choosing a sampling device.  Where detection
of  organics  at  low   levels  is  desired,  a  closer  evaluation of the  sampling
devices  potential for altering the sample may need to be conducted.

Bailers  are  commonly used  both  for  purging  and  sampling  water   from small
diameter, shallow  wells due to their relative  low  cost,  portability and  ease
of  maintenance.   A  disadvantage of the  bailer as  a sampling  device  is  the
potential aeration  and/or  degassing of  the sample during sample  collection.
The aeration is  the   result of repeated submergence  and  removal  of  the bailer
during  sampling,  which may result in  turbulent  flow of  water  in  the well-
bore.  Further aeration can occur  as  a result of pouring the collected sample
out the  top  of the bailer  into the sample bottles.   Aeration of a  sample when
using  a  bailer  can be minimized by gently  lowering  the  bailer  into the water
when collecting  the  sample.   Aeration/degassing  can be  further   reduced  by
utilizing a  bailer modified to include a bottom draw valve.  The device allows
emptying of  the  bailer at  a slow controlled rate, thus  avoiding  aeration of
the sample,  which occurs during decanting.  Improvements in sample  representa-
tiveness between  conventional  bailers  and bottom  draw bailers  have  been docu-
mented by Barcelona  (1984).

Field  and   laboratory testing  of  suction   lift  and  gas  displacement  pumps
indicates that  these pumps  are  consistently  below  average  in terms  of  the
accuracy of  the  sample delivered when compared  to  other  devices (Nielsen and
                                      6-8

-------
Yeates,  1985;  Schuller et  al.,  1981;  Barcelona et  al.,  1984).   The  suction
lift pump employs application of a negative pressure which can cause degassing
of the water sample.   Gas  displacement  pumps,  typically  air  or nitrogen lift,
can cause  gas  stripping of  carbon dioxide  (which  results in a change  in  in-
itial pH of the sample), or gas stripping of volatiles.

6.1.3  Proper Handling of Samples

6.1.3.1  Sample Preservation
Water samples may undergo  change with regard  to  their  physical,  chemical,  and
biological  state during  transport and  storage.   In  order  to  preserve  the
integrity of a sample after collection,  the samples are generally refrigerated
and/or preserved by the addition of acid or alkaline solutions.

In spite  of these practices of stabilizing samples, there is  a  potential  for
alteration of a sample during transport  and storage.  Particular  practices  and
areas of disparity that may contribute to the variance  of water quality during
the sample holding period are:

          1. Delaying  filtering  and  preserving  of  samples  until
             samples reach the laboratory.
          2. Aeration of the sample during filtration.
          3. Failure to filter samples  prior to  the addition of acid
             for preservation.
          4. The  lack  of  necessary  temperature reduction  for suc-
             cessful stabilization of the sample during transport.

A  field  experiment has  shown that the  delay  of preservation of  samples  can
lead to variation  in water quality analyses (Schuller,  et al., 1981).   In the
experiment, multiple samples were collected from one monitoring well installed
at an anaerobic  lagoon  and one  monitoring well  installed at  an inactive sani-
tary landfill.   Once  collected,  the  samples were  divided into four sets,  the
first set  being  preserved  immediately and  the remaining  sets  preserved 7, 24
and 48 hours after collection, by the addition of acid.  Each of the collected
samples  were  analyzed  for  calcium,  iron,  potassium,   magnesium,  manganese,
sodium and zinc, within the EPA prescribed holding times specified for each of
                                      6-9

-------
the parameters.  Iron showed the most dramatic change in concentration.   Seven
hours  after collection,  the measured  concentration of  iron  in  the  sample
collected from  the well  located  at  the  lagoon  was  .33 mg/1;  the concentration
of iron  in  the sample collected from the same well  and preserved  immediately
was 11.6 mg/1.   The  change  in  iron  concentration from the sample collected at
the  landfill  showed  a  change  in iron  concentration from 5.74 to <.08  mg/1
between  zero and  seven  hours after  collection and before  preservation.   Sig-
nificant changes were also noted for magnesium, manganese and zinc.

One  possible  explanation for  the  sample  alteration is  the aeration of  the
sample during  transfer  from the sampling device to  the  sample  bottle or from
the  sampling  device  to  a  holding  vessel  prior to  filtration, and  prior  to
fixation of the metals  by the addition  of  acid.   Where ground water  is  in a
reduced  state,  the  addition of oxygen  via aeration  can cause oxidation  of
ferrous  iron  to ferric  iron and subsequent  precipitation as  ferric  hydrox-
ide.   Once  allowed to form, much of the ferric hydroxide will  be removed  by
filtering prior to analyses.

A recent laboratory  experiment measures  the precipitation  of iron  from a col-
lected  sample  using  different  filtration  methods  and  different sampling  de-
vices.   The  filtration  methods tested included  on-line filtration,  vacuum
filtration  following transfer  from  a  holding vessel,  and  the  same  vacuum
filtration procedure  after a 10-minute holding time.   Sampling mechanisms used
included  a  bailer,  peristaltic pump,  bladder pump,  air and   nitrogen  lift
pumps,  and  a  submersible electrical  pump.   With each  sample  mechanism used,
the  samples handled  by  on-line filtration exhibited  higher  dissolved  iron
concentrations than samples  transferred to holding  containers prior to filtra-
tion.   The  10-minute holding period  appeared  to have no consistent effect on
the concentration  of measured iron  as  compared to  immediate  filtration from
the holding vessel  (Stolzenburg, et a!., 1986). The  study indicates  that the
turbulence and associated aeration of the sample during filtering can signifi-
cantly  alter  sample  quality.   In  fact, the study indicates  that  aeration of
the sample  during  filtration has at least  as  much  impact on  sample quality as
the sampling device  itself.
                                     6-10

-------
Many monitor  wells are completed  in  low yield, clay  rich  sediments.    It  is
impractical and in some instances impossible to complete these wells in such a
fashion that water samples  can  be  collected  free of  sediment.  EPA recommends
field acidification of samples collected for metals analysis to a pH less than
2 (EPA, 1982).  Acidification of unfiltered samples can lead to dissolution of
minerals  from  clays  in  the suspended solids.   Table  6-1  indicates that  the
measured concentrations of calcium and magnesium in samples  acidified prior to
filtration are directly related  to the  concentration of suspended solids.   On
the other hand, concentrations of calcium and magnesium in unacidified  samples
show no correlation  to dissolved solids (Kent, et al,  1985).   This is not to
say that  samples  should not  be acidified, but rather  that  samples should  be
filtered prior to acidification.  Otherwise, constituents of interest that may
occur naturally  in the formation  matrix may be dissolved  when acidified  re-
sulting in  a  sample  that is  not representative of the water contained in the
aquifer.

EPA  states  the  preservation  of samples  by  refrigeration  requires that  the
temperature  of collected  water samples  be  adjusted  to a temperature of  4
degrees Celsius immediately after collection and during shipment.  In order to
observe the effectiveness of  different  types of  ice  in cooling samples and in
order to determine the effort required to maintain  sample bottles at 4 degrees
Celsius, the cooling rates of water samples chilled by ice and the temperature
maintenance ability of  frozen blue ice  were recorded.   Ten  250 ml bottles and
twelve 500 ml bottles were filled with tap water.  The initial temperatures of
the  samples were  recorded.    Thermisters  (electronic   thermometers) were  in-
serted  through  small  holes drilled  in  the center  of  each  sample bottle lid.
The  bottles were placed  in  a 48 quart  cooler,  covered with  two (ten pound)
bags of  ice,  and  their temperatures monitored.  Readings were taken every 10
minutes until  the monitored  bottles  reached  their  desired  temperature  of 4
degrees Celsius.   These  bottles were  transferred  to  a  pre-cooled ice chest
filled  with blue  ice.   As  indicated  in  Figure 6-2,  the  temperature of  the
samples dropped to 4  degrees  Celsius  within 3 hours.   As shown in Figure 6-3,
the blue ice was successful in maintaining the bottles below 4 degrees Celsius
for 24  hours.   In  contrast, when ambient temperature samples were placed in a
48 quart  cooler and covered  only  with  blue ice,  the  samples  did not  reach 4
degrees Celsius (Figure 6-4).
                                     6-11

-------
TABLE 6-1.  Addition of Acidic Preservative Prior to Filtering
Sample Turbidity

1
2
3
4
5
6
7
8
9

22,000
18,500
9,700
8,600
5,200
3,400
3,100
2,200
1,900
Ca
2,442
1,980
1,452
1,452
915
827
704
453
286
Acidified
Mq
55
54
34
36
33
47
27
33
18
Unacidified
Ca
44
73
95
78
134
284
101
134
78
Mq
18
16
13
15
20
36
19
27
13
 All analysis  are  in ing/l
                                6-12

-------
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     LU
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          24
Figure  6-2.  Field Refrigeration of Samples Using  Water  Ice
                                   T
                 8   12   16   20
                  TIME CHOURSD
24  28
 Figure 6-3.   Bottles Placed in Crushed Ice  Chilled to 40ฐC,
             and  Transferred to Ice Chest Pre-ChilUd with
             Blue Ice.
                      6-13

-------
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48
       Figure 6-4.   Field Refrigeration of Sample  Using  Blue  Ice
                              6-14

-------
This experiment  suggests that when using  blue  ice  to  refrigerate,  the samples
must be  initially  chilled  using wet  ice.  Samples can then  be  transported  to
the laboratory in either blue ice or  wet ice.   However, when  using  wet ice for
an extended  period,  additional  ice may need to  be added to the ice  chest  to
maintain the recommended 4 degrees Celsius temperature.

In conclusion  to this section covering sampling strategy, there are  multiple
avenues  for  sample  alteration during collection including the  method  of  well
purging, the device used to sample the wells,  and the  method  of  sample preser-
vation.  It  has  been  demonstrated  that  the  alteration of a sample  that occurs
during sampling may be more or less quantified  by collecting  replicate samples
a  few  days  apart,  i.e.,  collecting samples  from the  monitoring system  on
Monday and  collecting another set of  samples  on  Thursday,  and  comparing the
variability  in  analytical  data between the two sets.  When the variation  is
significant, the well  sampling  protocol should be tested  in the field, e.g.,
comparing variations  in analyses resulting from different methods  of filtra-
tion, to determine the source or sources of sample alteration.

6.1.3.2  Chain-of-Custody
One consideration for  data  resulting from chemical analyses  is  the ability to
demonstrate  that the  samples  were  obtained  from  the  locations  stated  and that
they were not  tampered with before they  reached  the  laboratory.   Evidence  of
collection,  shipment,  laboratory receipt, and  laboratory  custody until dispos-
al must  be  documented to  accomplish  this.   Documentation  should be accom-
plished  through  a  chain-of-custody form  (Figure  6-5) that  lists  each sample
and  the  individuals  responsible  for  sample   collection,   shipment,   and
receipt.  A  sample is  considered "in  custody"  if it is:

          •  In a person's actual possession
          •  In view,  after being in  physical  possession
          •  Locked so that  no  one can tamper with it, after having
             been in physical custody
          •  In a secured area, restricted to  authorized  personnel.

The  chain-of-custody   form  should  be  signed  by each  individual  who  has the
samples  in their possession.

                                     6-15

-------




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6-16

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Multipart chain-of-custody forms may be used so that a copy can be retained by
the individual shipping the sample.

6.1.3.3  Preparation, Packaging, Handling and Shipping
Samples should  be placed  in containers compatible with the  intended  analysis
and  properly preserved.   Also,  control of  samples must  consider the  time
interval between  acquiring the  sample  and analysis  (holding  time) so  that the
sample is representative.

Samples to  be shipped off  site for chemical analysis are  normally placed in
ice  chests   and  packed  to prevent  breakage  during  shipment.   The ice  chest
should be sealed, addressed, identified, and placarded as  appropriate.

To  provide   necessary information  to the laboratory,  a  Request  for  Analysis
form should  be completed by the field personnel, or other  project personnel if
appropriate,  and  included with  the  chain-of-custody  record.   It is imperative
that the Request  for Analysis  be  provided so that analytical requirements are
defined and  sample holding times are not exceeded.

Transportation  should enable samples to arrive  at the laboratory  in  time to
permit testing  in accordance with  established  sample holding time and  project
schedule.

In many investigations, the  samples may be  transported  in private vehicles by
the  person  collecting the  samples.   At other  times,  samples may  be  sent by
common carriers.   Frequently,   commercial airlines  or bus companies will  not
accept samples  for   shipment.   Most samples should be shipped  by Federal  Ex-
press, Purolator, or other non-passenger earring transports.

6.1.3.4  Sample Storage
In general,  storage  of  sample  should be adequate  to prevent damage,  loss, or
unacceptable deterioration.  Soil  samples collected  for chemical  analysis may
require  specific  preservation  measures  to  insure sample  integrity.   Samples
should be  stored  in   a manner which  fulfills  the sample-specific preservation
requirements.   This may  require  use  of  teflon  lined  lids,  certain  sample
                                     6-17

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temperatures,  attention  to holding  times,  and use of  chemical  preservatives.
Samples  should not  be  subjected to  excessive amounts  of  moisture or  large
temperature  variations.    The  samples  should  not be  allowed  to freeze  if  in
situ characteristics  to  be determined by  testing  could be affected.   Indoor
storage  should be  employed,  where possible,  to provide  a controlled  environ-
ment.

6.1.4  RCRA Sampling versus Real World Sampling
After  examining a  monitor well  sampling  plan  or reading  through the  RCRA
guidance  document  on  sampling  and analysis,  it appears that following  the
careful  path  established  by the  EPA provides  an  appropriate procedure  to
achieve  accurate analytical results.  This is  the  intention  of RCRA,  but when
the  procedures are put  into  action in the  field,  the  scientist or  engineer
involved  comes to  a new understanding of what is possible and  what is  neces-
sary to  assure that  the  samples collected  accurately  represent the  conditions
of  the  water  in the  sampled  aquifer.   The preceding  sections  have addressed
specifics  involved  in a  sampling  program.   A few  more examples from  actual
sampling  situations follow in order to briefly ellaborate.

RCRA specifies that  soil  should be prevented  from contaminating  the  sampling
equipment or from entering the monitor well.   Basically this  may be  impossible
to accomplish.  Wind  and  rain are  the  two  major  factors which create problems
in  this  area.   If the field  personnel  has  to hike  through  mud or  the wind
keeps blowing  dirt  through the  air  around  the  sampling site,  it is  impossible
to eliminate  the entrance  of  dirt  into the well  or the sample.  The placement
of  a drop  sheet  to  prevent  contamination  of the  equipment  from  the  ground
around the  well may not be very effective.  To begin  with,  the sheet must be
anchored  down.  Simple tasks  like  this become  very difficult when considering
the  location of most  monitor wells.    If  enough  rocks  or  heavy objects  are
found  to prevent the drop cloth from blowing away,  then  it  is  difficult  to
prevent  soil  from  getting on top of the  drop  cloth.   If it  is raining  or has
rained recently, it  is easy  to  understand  that this  goal becomes difficult or
impossible.

Once the drop  cloth  is  in place, the next  obstacle  is to measure the water
levels  and  then decontaminate  the equipment  involved.   The decontamination
                                     6-18

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procedures outlined  in RCRA  guidance are  unrealistic given  that  most  sampling
programs  only  require one  person  in  order to  accomplish  all  of the  other
procedures involved.  Two people are normally required  to accomplish  the  tasks
required  to  comply  with  the RCRA decontamination guidelines.  The intentions
of these procedures  are obvious, but their impracticality and  cost  outmeasures
their  effect on the  outcome  of the analytical results.   In most wells  only
about  1 foot of the  E-line will actually enter the water. After  purging  three
casing  volumes of  water from  the well,  the  effects   of  any  slight  cross-
contamination  should be undetectable.

Disposal  of  the water  purged  from a  monitor well  creates a great  problem.
RCRA guidelines  recommends  disposal  of purged water in  55-gallon  drums.   The
acquisition  of large storage drums, their transportation,  and their  eventual
disposal  is  a  major  task to accomplish.  If purging involves hand bailing, the
weight  of  the  bailer creates  another  problem.   Not only are  stainless  steel
bailers expensive,  they  are  heavy.   Larger bailers for  large diameter  wells
are also heavy.

6.2  SAMPLE  ANALYSIS AND DATA INTERPRETATION
During  the  past several  years, hundreds of  thousands of ground  water samples
have  been collected  from  ground  water monitoring  wells and the  results re-
ported  to the  regulatory  agencies.   The  results  of these  analyses  are  most
frequently   interpreted  by   individuals  other  than  those  who  performed  the
analysis.  Many  of  these  people have  not  been inside an analytical laboratory
and may not  understand the limitations of the equipment and/or methods used to
analyze the  water.    Hence,  they  do not  have  the education or  experience to
understand the  limitations of the analysis.  One method that has  been utilized
is  a   statistics  approach  to  try to  view data  strictly  from  an "objective
approach."   Unfortunately,  most geologists and engineers do  not have an ade-
quate  knowledge of statistics;  therefore, this approach has  limitations.

The  basis for  interpreting  analytical results must  include  a  knowledge  of
monitor well  construction,  geohydrology,  geochemistry, and  analytical  tech-
niques.   Also important  is an  understanding  of  the  factors  affecting the
validity of  a  set of data and the limitations on data interpretation.
                                     6-19

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6.2.1  Use of Blanks
In addition  to  the problem of equipment limitation, other  factors  can influ-
ence  the  results of  lab  analysis.   One way of attempting  to  determine these
effects is with the use of travel blanks, field blanks  and method blanks.

Travel blanks are  samples  of  distilled  water  placed  in bottles and  sealed and
sent  to  the sample location  and  returned  to the laboratory unopened.   These
are then  analyzed for  selected  compounds.   Those found  are generally common
laboratory chemicals used  in the laboratory.  Table 6-2 shows the results from
a recent Arkansas  investigation.

Another QA/QC technique  is the  use  of  field blanks.   Distilled water is taken
in a  sealed bottle to  the field and during  a routine sampling  event is de-
canted  into  another bottle.  This provides an  indication of possible effects
of  adsorption  from  the  air  or  the  existence of  sample  handling  problems.
Table 6-2 also contains the results for field blanks for the Arkansas Investi-
gation.

Method blanks are  used  to determine  if  there  are  errors caused by the labora-
tory method  and/or if the  chemicals used in the method  contain  items of inter-
est.   Tables  6-3 and  6-4 show  the  results  from  two separate  laboratories
working on the same project.  Many compounds are commonly found in analyses of
this  type.    Some  more of  the  frequently  detected  compounds  in  method blank
analysis are  indicated  in  Table 6-5.

6.2.2  Choice of Analytical Parameters
When  conducting  a contamination  study,  decisions must  be made as  to what
parameters  will  be analyzed  for  in  the laboratory testing  program.   For the
most part,  a laboratory only  reports  to you the value  for compounds for which
you ask  and/or pay.   For example, if  an  analysis  for benzene,  toluene, and
ethylbenzene was requested, the lab may only report values for these compounds
and not report the presence of other chemicals that may have been found during
the analysis for the requested items.  During the early 1980's, many companies
conducting contamination  studies would ask for priority pollutants analysis of
the ground water and would  frequently obtain laboratory analysis reports which
stated that  none were detected.  It was frequently concluded that the site was
                                     6-20

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          TABLE 6-2

TRAVEL AND FIELD BLANK RESULTS
   ARKANSAS SUPERFUND SITE



Travel Blank
Methylene Chloride
Acetone
2-butanone
Field Blank
Methyl ene Chloride
Acetone
2-butanone
Chlorotom

Range
(ug/1)

1-3
4
1

2
3-4
2
1
No. Of
Samples


3
3
3

3
3
3
3
No. of Positive
Results


3
2
1

1
2
1
2
             6-21

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                                   TABLE  6-3
               RESULTS OF ORGANIC ANALYSIS OF LABORATORY BLANKS
                      OKLAHOMA STATE  DEPARTMENT  OF HEALTH
                          LABORATORY  (MATRIX  UNKNOWN)
Compounds Found

Di-N-butylphthalate
Bis (2-Ethylhexyl) phthalate
2,4,6-Trichlorophenol
Methylene Chloride
Trichloroethane
Toluene
Chloroform
1,1,1-Trichloroethane
Range
yg/1 (ppb)
1.8-170
440-10,000
150
3.1-22
2.3-17
3.1-4.7
6.3-7.1
3.4-6.5
No. of
Analysis
8
8
8
11
11
11
11
11
No. of Positive
Results
2
2
1
11
10
3
8
2
                                  TABLE 6-4

              RESULTS OF ORGANIC ANALYSIS OF LABORATORY BLANKS*
                     GULF SOUTH RESEARCH INSTITUTE
                         NEW ORLEANS, LOUISIANA
Compounds Found

Methylene chloride
Acetone
Chloroform
2-Butanone
Di-N-butylphthalate
Acetom'trile
Bis(2-Ethylhexyl) pthalate
Hexane
Range
ug/Kg (ppb)
1,600-10,000
3,500-7,300
3,100-3,300
2,300-7,700
7,800
2,000-10,000
3,600-3,800
5,000
No. of
Analysis
11
11
11
11
4
11
4
11
No. of Positive
Results
7
9
2
7
1
11
2
2
* Matrix Methanol
                                     6-22

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                   TABLE 6-5
ORGANIC COMPOUNDS FOUND IN METHOD BLANK ANALYSIS
       Di-N-butylphthalate
       2,5-dimethylfuran
       Acetic acid, 1-methylethyl ester
       Heptane, 2,3-dimethyl octane
       Hexadecanoic acid
       Butyl benzylphthalate
       Bis (2-ethylhexyl) phthalate
       2-hexanone
       Phosphoric acid, 2 ethylhexyl-diphenylester
       2-butanone
       Squalene
       N-nitrosodiphenylamine
       Methylene chloride
       Chloroform
                      6-23

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not  leaking  because no  priority  pollutants were  found  in the ground  water.
Later studies  that  have  concentrated  on  waste-specific chemical analyses  have
found the waste-related  compounds to  be  present  in ground  water systems which
were previously  thought  to be "clean."  Those parameters  were not  previously
requested, therefore, were not reported.

In recent  times, regulatory agencies  have  begun to ask  for Appendix  VIII  or
IX,  Skinner  list,  or  other more comprehensive  lists  of  analyses.   Although
this is  certainly a step  in the right direction,  the  absolute application  of
these "guidelines"  can waste tremendous  amounts  of money.   In  a recent inves-
tigation  in  Arkansas,  over 145 samples  of  soil, waste and ground  water  were
collected and  analyzed for hazardous substance lists of volatile organics, and
acid and  base/neutral  (ABN) extractables.   Of  these analyses,  only  four major
volatile  organics  and   three  ABN   extractables  were  detected  on  a  routine
basis.    A review of the profiles of  waste  buried  at the  site, and/or collec-
tion of several  samples  of the waste and  performance of a comprehensive analy-
sis  could have  lead  to  the identification of the major  contaminants.   Over
$81,000  worth of analyses could  have  been  saved, by  having only  selected
analyses performed.  Tables 6-6, 6-7, and 6-8 list the  major organic compounds
frequently analyzed for  during  hazardous waste site studies.   The tables also
list the  general sources  of  these  organics.   A  review  of these  tables and
suspected wastes  can lead  to a significant reduction in anlaytical cost.

6.2.3  Detection  Limits
Over the  last several  years,  analytical  methods have  improved and  where  con-
centrations of chemicals or ions were reported in  parts  per million, they are
now  reported  in  parts  per billion.   Parts  per trillion  analysis  is currently
possible for  many elements and  compounds.   However, detection  limits are also
a  function  of  the  amount  of  time  that  one  has  to  analyze  samples.   Most
analytical  work today  for   ground   water  contamination  is  performed  at
commercial laboratories.   Hundreds  of samples are  analyzed on a  daily basis.
The  labs do not  charge sufficiently for each analysis to  treat  routine samples
as  individual  research  projects.     Most  major  laboratories  today  are  EPA
certified or  certified  by  a state   agency.   These  laboratories  follow general
QA/QC programs that meet  state and  federal  standards and routinely analyze
blanks,  duplicates  and  spikes  as  part  of  their programs.  However,  samples
                                     6-24

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                                  TABLE 6-6
                  VOLATILE  HAZARDOUS SUBSTANCE LIST COMPOUNDS

**acetone -  paints,  varnishes,  lacquers,  sealants, adhesives, cellulose  ace-
   tate solvent;  natural microcomponent in blood and urine;  common  laboratory
   solvent used to extract solid waste samples,  and dry  glassware.

benzene -  motor  fuels;  solvent  for fats,  inks,  oils,  paints, plastics,  and
   rubber; photogravure printing;  mfg.  of  detergents,  explosives,  Pharmaceuti-
   cals, and dye-stuffs.

*benzo  (a)  pyrene -  by-product  of combustion;  sources:   coal refuse  piles,
   outcrops, abandoned  coal  mines,  coke mfg., external  combustion  of  anthra-
   cite coal.

bromomethane (methylbromide) - soil and space fumigant;  organic synthesis.

2-butanone  (methy ethyl  ketone  or MEK) - resin  solvent;  paint strippers;  wax
   production; cements; adhesives; cleaning fluids.

*carbon  disulfide  -  mfg.  rayon,  cellophane,   carbon  tetrachloride,  rubber
   chemicals,  soil  disinfectants,  electronic  vacuum   tubes;  solvent  (phor-
   phorus,  sulfur,  bromine,  selenium,  fats,  resins,  rubbers);  mfg.  grain
   fumigants, soil conditioners, herbicides;  paper mfg.; pharmaceutical mfg.

carbon  tetrachloride  - fire extinguisher mfg.; dry cleaning  operations;  mfg.
   of  refigerants, aerosols  and  propellants;  mfg. of  chlorofluoromethanes;
   extractant, solvent; veterinary medicine;  metal  degreasing.

bromodichloromethane  -  fire-extinguisher fluid   ingredient;  solvent  (fats,
   waxes, resins);  synthesis  intermediate;  heavy liquid for  mineral  and  salt
   separations.

bromoform  - pharmaceutical  mfg.;  ingredient  in  fire-resistant  chms.;  gage
   fluid; heavy  liquid  in  solid separations based on differences  in  specific
   gravity; geological assaying; solvent for waxes, greases and oils.

chlorobenzene -  solvent  recovery  plants;  intermediate in  dyestuffs  mfg.;  mfg.
   aniline,  insecticide, phenol, chloronitrobenzene.

chloroethane  (ethyl  chloride) -  mfg.  of  TEL and  ethylcellulose;  anesthetic;
   organic  synthesis;  alkylating  agent;   refrigeration;   analytical  reagent;
   solvent.

2-chloroethylvinylether  -  mfg.  of  anesthetics,   sedatives,  and  cellulose
   ethers.

chloroform - mfg. of refrigerant and plastics; solvent.

chloromethane  (methylchloride)  -  mfg.  silicones, tetraethyllead,  synthetic
   rubber and methyl cellulose; refrigerant mfg.; mfg.  fumigants;  low tempera-
   ture  solvent;  catalyst  carrier in  polymerization;  medicine;  extractant;
   propellant; herbicide.
                                     6-25

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                                  TABLE 6-6
                                  Continued
cis-l,3-dichloropropene - soil fumigant;  nematocide.

dibromochloromethane  -  mfg.  fire extinguishing  agents;  mfg. aerosol  propel-
   lants; mfg. refrigerants;  mfg. pesticides;  organic synthesis.

1,1-dichloroethane - vinylchloride;  chlorinated  solvent  intermediate;  coupling
   agent  in  gasoline; paint,  varnish  and  finish removers; metal  degreasing;
   ore flotation.

1,1-dichloroethene  (1,1-dichloroethylene) - adhesives; component of  synthetic
   fibers.

1,2-dichloroethane  (ethylenedichloride)  -  mfg.  of  vinyl chloride;  mfg.  of
   tetraethyllead;  intermediate  insecticide  fumigant;   tobacco   flavoring;
   constituent  in paint,  varnish  and finish removers;  metal  degreaser;  ore
   flotation.

1,2-dichloropropane - intermediate for  perchloro-ethylene and  carbon  tetra-
   chloride;  lead scavenger  for antiknock  fluids;  solvent; soil fumigant  for
   nematodes.

ethylbenzene - styrene mfg.;  solvent,  asphalt, gasoline,  and  naphtha constitu-
   ent.

2-hexanone (methylbutylketone) - solvent.

methylene chloride  -  paint stripping; degreasing; aerosols; synthetic  fibers
   mfg.;  refrigerant; textiles;  coatings;  blowing  agent; common  laboratory
   solvent used extensively in extraction of sample for  GC/MS.

4-methyl-2-pentanone  (MIBK or methylisobutylketone) -   solvent  for  paints,
   varnishes,  nitrocellulose  lacquers;  mfg. of  methylamylalcohol;  denaturant
   for alcohol.

styrene - mfg. styrene, polystyrene; mfg. synthetic rubber; ABS  plastics mfg.;
   mfg. resins, insulators; mfg. protective coatings  (styrene-butadiene latex,
   alkyds).

1,1,2,2-tetrachloroethane - mfg. 1,1-dichloroethylene; solvent for  chlorinated
   rubber and  other organic  materials; insecticide mfg.;  bleach mfg.;  paint,
   varnish, rust  remover mfg., soil  fumigant;  cleansing  and degreasing metals;
   herbicide;  alcohol denaturant.

tetrachloroethylene (tetrachloroethene)  - organic  chemical mfg.; dry cleaning
   operations;  metal  degreasing; solvents  for   fats, greases,  rubber,  gums;
   mfg. paint  removers, printing inks; mfg.  of fluorocarbons.

trans-l,2-dichloroethylene (trans-l,2-dichloroethene) -  solvent for  fats  and
   phenols; rubber mfg.; dyes and lacquers; perfumes; thermoplastics.

trans-l,3-dichloropropene - soil fumigant;  nematocide.

1,1,1-trichloroethane  (methylchloroform  or  chloroethene)  -  degreaser;  dry-
   cleaning agent; vapor degreasing agent;  propellant.


                                     6-26

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                                  TABLE 6-6
                                  Continued
1,1,2-trichloroethane  - mfg.  1,1-dichloroethylene;   solvent  for  chlorinated
   rubber and various organic materials (fats,  oils,  resins,  etc.).

trichloroethene  (trichloroethylene or  TCE)  - solvent;  dry-cleaning  agent;
   chemical intermediate in the production of pesticides,  waxes,  gums,  resins,
   tars, paints, and varnishes.

*toluene  - mfg.  of  benzene  derivatives; caprolactam  mfg.;  saccharin  mfg.;
   perfumes;  component  of  gasoline;   paint  and  coatings solvent;  adhesives
   solvent; asphalt and naphtha constituent.

vinyl acetate - used in polymerization processes to produce polyvinyl  acetate,
   polyvinyl  alcohol,   and  vinyl   acetate  copolymer.   Polymers  are  used  in
   adhesives, paints, paper coatings and textile finishes.

vinyl chloride  -  vinyl monomer in the manufacture  of  polyvinyl  chloride  and
   other resins; solvent; chemical intermediate.

*xylene - petroleum distillation;  coal tar distillation; mfg.  terepthalic acid
   for  polyester;  solvent  recovery  plants;  mfg.  isophthalic acid,  aviation
   gasoline;  protective coatings   mfg.;  solvent  for alkyd resins,  lacquers,
   enamels, rubber cement;  insecticide mfg.;  pharmaceutical mfg.


*Can  also  occur naturally  or  associated with  coal  or  coal  combustion.   Can
also  occur  naturally or associated with  organic  deposits such  as  coal,  lig-
nite, peat, etc.  Also found in waters associated with these  deposits.

**Common laboratory contaminant or lab chemical.

OCommon name appears in parenthesis following compound.

Source:  Handbook of Environmental Data on Organic Chemicals,  Verschueren,  K.

         Mass Spectrometry  of  Priority Pollutants,  Middleditch,  B.,  Missler,
         S., and Nines, H.

         The Merck Index, Windholz, Budavari, Stroumtsos and  Fertig
                                     6-27

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                                  TABLE 6-7
              ACID EXTRACTABLE HAZARDOUS SUBSTANCE LIST COMPOUNDS

benzole  acid  - food  preservative;  pharmaceutical  and cosmetic  preparations;
   mfg. of alkly  resins;  intermediate in the synthesis of  dyestuffs  and  phar-
   maceuticals; production of phenol  and  caprolactam;  plasticizer mfg.

4-chloro-3-methylphenol (p-chloro-m-cresol)  -  external  germicide; preservative
   for glues, gums, inks, textile and leather  goods

2-chlorophenol - organic synthesis

2,4-dichlorophenol - organic synthesis

2,4-dimethylphenol  (2,4-xylenol)  -  intermediate  in  mfg.  of phenolic  antioxi-
   dants;  pharmaceutical  mfg.;  plastics and  resins  mfg.; disinfectant  mfg.;
   solvent mfg.;   insecticides and  fungicides;  rubber chemicals;  mfg.  poly-
   phenylene oxide; wetting agent; dyestuffs;  cresylic acid constituent

4,6-dinitro-2-methyphenol - dormant ovicidal  spray for fruit trees

2,4-dinitrophenol-  used  in  the  manufacturing of dyestuff  intermediates,  wood
   preservatives,  pesticides,  herbicides,  explosives,  chemical  indicators,
   photographic developers, and also in  chemical  synthesis

2-methylphenol(cresol) -  disinfectanct;  foot  antioxidant;  perform mfg.;  dyed
   mfg.;  plastics  and  resins mfg/  herbicide  mfg.;  ore floatation;  textile
   scouring agent; organic intermediate;  mfg.  of  slaicycladehyde; surfactant

4-methylphenol(cresol) -  disinfectant; ore  floatation agent;  intermediate  in
   the manufacture of chemicals,  dyes, plastics,  and  antioxidants

2-nitrophenol - intermediate in organic  synthesis;  indicator

4-nitrophenol  -  intermediate in  organic  synthesis;  production  of  parathion;
   fungicide for leather

pentachlorophenol  - mfg.  insecticides, algicides, herbicides,  and  fungicides;
   preservation of wood and wood  products;  mfg.  of  sodium pentachlorophenate

phenol  (carbolic  acid,  phenic acid)  - mfg.  of explosives, fertilizer,  coke,
   illuminating  gas,   lampblack,   paints,  paint  removers,  rubber,   asbestos
   goods, wood preservatives, synthetic resins,  textiles,  drugs, pharmaceuti-
   cal  preparations,  perfumes, bakelite,  and  other plastics;   as a  disfinfec-
   tant in the petroleum, leather, dye and  agricultural industries

2,4,5-trichlorophenol - fungicide; bactericide

2,4,6-trichlorophenol -  organic  chemical industry; pesticide mfg.; mfg.  anti-
   septics, bactericides, fungicides, germicides; mfg. wood and glue  preserva-
   tives; used as  anti-mildew agent for  textiles

() common name appears in parentheses following compound

Sources: Handbook  of Environmental Data  on  Organic  Chemicals,  Verschueren,
         K.,  Handbook  of  Toxic  and Hazardous  Chemicals  and  Carcinogens.
         Sittig,  M.,   The Merck  Index, Windholz,  Budavari,  Stroumtsos  and
         Fertig


                                     6-28

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                                  TABLE 6-8
          BASE/NEUTRAL EXTRACTABLE HAZARDOUS SUBSTANCE LIST COMPOUNDS
acenaphthene -  coal  tar,  dye intermediate;  mfg. of plastics,  insecticide  and
   fungicide
acenaphthylene -  in  soots generated by the combustion of  aromatic  hydrocarbon
   fuel doped with pyridine; coal  refuse  heaps;  coke ovens
anthracene - used in dyes
benzo (a) anthracene - gasoline, bitumen,  crude  oil; asphalt  hot-mix  emission
benzo  (a)  pyrene  -  by-product of  combustion;  coal  refuse  piles,  outcrops,
   abandoned coal mines; coke mfg;  external  combustion of  anthracite  coal
*benzo (b)  fluoranthene  -  petroleum based fuel, gasoline, diesel, etc.;  coal
   refuse heaps; coke ovens
benzo (g,h,i) perylene - coal tar,  pitch  distillate
benzo (k) flouranthene - petroleum based  fuels,  bitumen, crude  oil
benzyl butyl phthalate - plasticizers,  vacuum pump fluids
benzyl alcohol - perfumes and flavors;  solvent;  intermediate; inks; surfactant
bis (2-chloroethoxy) methane - selective  solvent;  textile  mfg.  and  cleaning
bis (2-chloroethyl) ether - fumigants;  processing  fats,  waxes,  greases,  cellu-
   lose  esters;  general solvent; insecticide mfg.; textile  mfg.  (scour  tex-
   tiles) and  cleaning;  mfg.  butadien, medicinals  and Pharmaceuticals;  selec-
   tive solvent; constituent in paints, lacquers,  varnishes
bis  (2-ethylhexyl)  phthalate  (dioctyl  phthalate)   -  plasticizer  for  resins;
   mfg. of organic pump fluids; frequently found in lab  blanks
4-bromophenyl phenyl ether (methyl  ethyl  ketone) - chlorinated  insecticides
4-chloraniline - dye intermediate;  Pharmaceuticals; agricultural  chemicals
2-chloronaphthalene  -  production  of electric condensers,   insulation  of elec-
   tric cables  and wires;  additives to extreme pressure  lubricants;  supports
   for storage batteries; coating in foundry use
4-chlorophenyl phenyl ether - selective solvent; nonsystemic  insecticide
chrysene - high octane gasoline motor-oils;  bitumen; crude oil
dibenzo(a,h) anthracene - used in wood  preservatives; gasoline  additive; found
   in coal tar
dibenzofuran -  (coumarone) - mfg. of coumarone-indene resins
                                     6-29

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                                  TABLE 6-8
                                  Continued


di-n-butyl  phthalate  -  plasticizer;  cosmetics  (fingernail  polish);   safety
   glass;  insecticides;  printing  inks;  paper  coatings;  adhesives;   textile
   lubricating agent

1,2-dichlorobenzene  -  mfg  of solvent;  dye  mfg.;  fumigant and  insecticide;
   metal polishes; industrial odor control

1,3-dichlorobenzene  -  mfg.  of  solvent; dye mfg.;  fumigant and  insecticide;
   metal polishes; industrial odor control

1,4-dichlorobenzene  -  mfg. moth repellants; mfg.  air deodorizers; mfg.  dyes
   and intermediates; Pharmaceuticals mfg.;  soil  fumigant;  pesticide

3,3'-dichlorobenzidine  -  intermediate  in the  manufacture of  azo pigments;
   curing agent for  isocyanate terminated resins,  for urethane  resins

diethylphthalate  -  plasticizer  mfg.; plastics mfg.  and  processing; explosive
   (propellant)  component;  dye   application  agent;  wetting  agent;   camphor
   substitute; perfumery; alcohol  denaturant;  mosquito repellant

dimethyl pthalate -  plasticizer for cellulose  ester plastics;  insect repellent

2,4-dinitrotoluene  - mfg.  TNT, urethane  polymers,  flexible and  rigid  forams
   and surface coatings, dyes; organic synthesis

2,6-dinitrotoluene - mfg. TNT; urethane polymers,  flexible  and  rigid foams and
   surface coatings, dyes;  organic synthesis

di-n-octyl phthalate - plasticizer mfg.; plastics mfg. and  recycling,  process-
   ing; organic pump fluid

*fluoranthene  -   crude  oil,  coal  tar, wood  preservatives, motor-oils;  coke
   ovens; coal refuse heaps

fluorene - coal tar; wood preservative; coke oven emissions

hexachlorobenzene -  mfg. of  pentachlorophenol,  wood  preservative;  fungicide,
   seed  treatment;   used  in  production  of  aromatic fluorocarbons;   organic
   synthesis,  impregnation of paper;  in technical  pentachlorophenol;  herbi-
   cides, pesticides

hexachlorobutadien  - solvent for natural rubber,  synthetic rubber and  other
   polymers;  heat transfer  liquid,  transformer  liquid,  and hydraulic  fluid;
   washing liquor for removing hydrocarbons

hexachloroclopentadiene  -  key intermediate in the  synthesis of  stable  chlori-
   nated cyclodiene  insecticides  including aldrin,  dieldrin,  endrin,  endosul-
   fan, heptachlor,  chlordane, isodrin, and  mirex;  mfg. of  nonflammable resins
   and shock proof plastics,  acids, esters,  ketones and fluorocarbons
                                     6-30

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                                  TABLE 6-8
                                  Continued
hexchloroethane  -  mfg.  smoke candles  and  grenades;  by-product of  industrial
   chlorination  processes;  plasticizer  for  cellulose  esters;  minor  use  in
   rubber  and  insecticidal   formulations;  medicinal  mfg.;   moth   repellant;
   retardant  in  fermentation  process;  fire extinguishing fluids mfg.;  camphor
   substitute in nitro cellulose solvent

indeno (l,2,3-c,d) pyrene - gasoline;  motor-oil;  coke oven  emissions

isophorone - solvent; intermediate for alcohols,  raw  material  for 3,5-dimethy-
   laniline;  solvent  for  polyvinyl   and   nitrocellulose  resins;   lacquers,
   finishes mfg.; pesticide mfg.

2-methylnaphthalene - coal tar pitch,  coal  processing

naphthalene  - mfg.  source:    petroleum  refining;  coal tar  distillation  in
   commercial  coal  tar;  moth ball mfg.;  mfg.  pesticides, fungicides,  dyes,
   detergents  and wetting  agents,  synthetic  resins,  celluloids,   lampblack,
   solvent; lubricants; motor fuel mfg.

2-nitroaniline -  intermediate for  dyes and antioxidants; gasoline gum  inhibi-
   tors; medicinals for poultry; corrosion  inhibitor

3-nitroani1ine -  intermediate in  the  manufacture of  dyes,  antioxidants,  phar-
   maceuticals, and pesticides

4-nitroaniline -  intermediate for  dyes and antioxidants; gasoline gum  inhibi-
   tors; medicinals for poultry; corrosion  inhibitor

nitrobenzene  -  mfg.  aniline  and dyestuffs;  solvent  recovery  plants;  mfg.
   rubber chemicals,  drugs,  photographic chemicals;  refining  lubricants  oils;
   solvent  in TNT  production; solvent  for  cellulose  ethers; cellulose  acetate
   mfg.; constituent  in metal polish  and  shoe polish  formation

n-nitroso-di-n-propylamine - contaminant  of herbicide Treflan  (Trifluralin)  in
   concentrations up  to 150 ppm

n-nitrosodiphenylamine - gasoline additive; analytical  chemistry  in  the deter-
   mination of cobalt; an accelerator in  vulcanizing  rubber.   It  decomposes  in
   GC analysis to  be  come diphenylamine, and  is  detected as diphenylamine,  so
   is essentially inseparable from it by  normal GC  methods

*phenanthrene  -  dyestuffs;  explosives;  synthesis  of  drugs;  biochemical  re-
   search

*pyrene - gasoline, coal tar, wood preservative sludge, motor-oil

1,2,4-trichlorobenzene - solvent in chemical  manufacturing  dyes and  intermedi-
   ates;  dielectric  fluids;  synthetic transformer oils; lubricants;  insecti-
   cides

* can also occur naturally or associated  with coal  or coal  combustion
** common laboratory  contaminant of lab chemical
() common name appears in parenthesis following compound
                                     6-31

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                                  TABLE 6-8
                                  Continued
Sources: Handbook of Environmental Data on Organic Chemicals, Verschueren, K.
         Mass  Spectrometry  of Priority Pollutants, Middleditch,  B.,  Missler,
         S., and Nines, H.
         The Merck Index, Windholz, Budavari, Stroumtsos and Fertig
                                     6-32

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that have  matrix  problems  or samples that are heavily  contaminated  can  cause
extreme  scheduling  problems in  laboratories  unless  the samples are  diluted.
When a  sample is diluted  prior  to being analyzed, the detection  limit  rises
proportionally to the  dilution  factor.   This practice  makes  it  difficult  for
an  investigator  to  compare results  from  one analysis to another  analysis  in
absolute terms and in fact can lead to incorrect  determinations concerning  the
presence or absence of contaminants.

6.2.4  Analytical Precision and Matrix Effects
Most analytical techniques were developed to look for impurities  or to isolate
chemical species.   However,  in contamination studies we frequently  have mix-
tures of waste with water and soil material.  Individuals  interpreting results
of analysis should be aware of equipment and operator limitations.   In running
a common analytical  method,  for instance GC/MS,  looking for  large numbers  of
compounds  at  a single  run, sample matrix effects may occur.   For  example,  if
one compound  exists  at a high concentration  and another at a  very low level,
then the  analytical  precision is  not the  same  for both compounds.   In  addi-
tion, many of  the techniques are qualitative and  not  quantitative methods.

When  dealing  with  organic  compounds,  extreme  care  must  be  exercised  when
accepting  reported  concentrations  as  being  a  "fact."   Most chemists  have
recognized  this   and  there  are  ranges  for  QA/QC that they  are  willing  to
accept.  Table 6-9 contains the U. S. Environmental Protection Agency (EPA)  QC
limits  for matrix  spike/matrix  spike  duplicate  recovery  results for  water
samples and (soil/waste/sludge) samples.

Extreme care should be used in interpreting relative  concentrations of organic
compounds when comparing up-dip to down-dip monitor wells.   For instance, if a
lab reported  concentrations of benzene  in  ground water  downgradient  of a site
to be 125 ppb  and upgradient to be 76 ppb, one might  infer a direction of flow
from the chemical  analysis alone.   However,  a review of Table 6-9 shows that
this range of  values  is  within  our QA/QC and any value reported between these
ranges may in  fact  be  the  same number.   A review of  77 soil surrogate percent
recovery analyses for  volatiles  analysis  performed during a recent investiga-
tion indicated 11 analyses were outside the QC limits for Toluene-DB (81-117),
four analyses  were  outside the  limits  for BFB  (74-121), and  all  were within
                                     6-33

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                                  TABLE 6-9
                         QC LIMITS FOR WATER AND SOIL
Fraction

Volatiles
Base/Neutrals
Acids
Pesticides
     Compound

1,1-Dichloroethene
Trichloroethene
Chlorobenzene
Toluene
Benzene

1,2,4-Trichlorobenzene
Acenaphthene
2,4-Dinitrotoluene
Di-n-butylphthalate
Pyrene
N-nitrosodi-n-propylamine
1,4-Dichlorobenzene

Pentachlorophenol
Phenol
2-Chlorophenol
4-Chloro-3-methylphenol
4-Nitrophenol

Lindane
Heptachlor
Aldrin
Dieldrin
Endrin
4,4'-DDT
Water Samples
QC Limits
 Recovery

  61-145
  71-120
  75-130
  76-125
  76-127

  39- 98
  46-118
  24- 96
  11-117
  26-127
  41-116
  36- 97

  9- 103
  12- 89
  27-123
  23- 97
  10- 80

  56-123
  40-131
  40-120
  52-126
  56-121
  38-127
Soil Samples
QC Limits
Recovery

  59-172
  62-137
  60-133
  59-139
  66-142

  38-107
  31-137
  28- 89
  29-135
  35-142
  41-126
  28-104

  17-109
  26- 90
  25-102
  26-103
  11-114

  46-127
  35-130
  34-132
  31-134
  42-139
  23-134
                                     6-34

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the  limits  (70-121) for  1,2-dichloroethane D4.  The  chemist reports  that 6 of
the  11  samples  that failed  the QC test were  strongly affected  by the  matrix
(in  other  words,   somethi-ng else  in  the  sample  was  interfering  with  the
results).   For the 77 samples discussed, only  four samples were outside  the QC
limits  for  semi-volatile  compounds.  One  should note  here that the  QC  window
for  semi-volatile compounds  is  generally larger than for the volatile QC.

A review  of 50  water surrogate percent  recoveries  for the same investigation
indicated only two  samples were out  of  QA/QC  limits  for toluene-DB  (88-110).
However,  out  of  35 water  surrogate results  for semi-volatile  analysis,  over
half were out  of limits for  at  least one compound.

6.2.5   Sources of Contamination in  the Laboratory
As  discussed  earlier,  there are  other sources for  chemicals  identified  in
laboratory  reports.   The  following table  lists the possible  sources of com-
pounds  recently  found  in  analysis  of  laboratory  blanks  for  a particular
project.
                              Common    Solvent Artifacts          Dirty Glassware
                               Lab           or         Natural        or
      Compound               Contaminant     Impurities     Products     Syringe
      di-N-butylphthalate

      butylbenzylphthalate
      bis(1-ethylhexyl)phthalate
      2,5-dimethyl-furan

      4-methyI-octane

      hexadeconic acid

      squaIene
      methylene chloride

      chrysene
                                         6-35

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The  chrysene  found  in  the laboratory blanks  is probably  the  result of  the
laboratory  not  adequately washing  out glassware  or syringes  because it  is
known that chrysene was found in samples  analyzed on that day,

6.2.6  Adsorption of Air Emissions
Even when the greatest  care  is  exercised  in  the  field,  the possibility exists
for  contamination  by  absorption  of  air  emissions.     In  many  chemical/
petrochemical complexes  there  are odors.  This  leads to  the  conclusion  that
there are concentrations  of  chemicals in the air.   Recent data indicate  that
organics may  be absorbed from  the  atmosphere  into the water sample  when  de-
canting from the  bailer  to the  sample bottle.   In one case, eleven monitoring
wells were  sampled  to determine the  lateral  and  vertical  extent of nitrotolu-
ene and dinitrotoluene isomers relative to surface impoundments containing  DNT
and DNT process by-products.  During  collection  of  the  samples, corresponding
field blanks were collected  at  each  monitor  well  to monitor potential absorp-
tion of organics from the air by the collected  water sample.  The field blanks
consisted  of distilled  water;  the  water  passed  between  two glass  sample
bottles approximately  six times at  the  well  site prior to  collection of  the
well water  sample.   Water quality  results for  both  the well   sample  and  the
field sample blank  are  included in  Table  6-10.   The average percent variation
in concentration  of 2,4-DNT  and 2,6-DNT  in the  well  water, excluding outside
values, as measured by the field blank, is 6  and  7 percent, respectively.   The
percent  variation  presents  the potential  DNT  available  for  absorption,  as
indicated by concentrations measured in each  corresponding field blank.

6.2.7  Sources of Sample Contamination in the Field
There is an abundance of literature about the development of pristine drilling
and  sampling  procedures  for  monitoring  disposal  site.   In practice,  these
conditons are extremely  hard  to meet.  Some sources  of self-contamination of
monitor wells include pipe dope applied  to the joints of drill pipes, leaking
hydraulic  fluid  from  the drilling  rig, and  foreign material  on the  drill
pipe.   Under the  adverse drilling  conditions of most waste  sites,  pristine
drilling  is almost  impossible.   Each  investigation should  be  planned  and
carried out  to  minimize self-contamination,  and/or sufficient  data should be
developed to document the influence of completion procedures.
                                     6-36

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                                       TABLE  6-10
                 Organic Analyses of Well  Water and Corresponding Field
                Blanks  -  2,4-Oinitrotoluene,  2,6-Oinitrotoluene
Well No.
1

2

3

4

5

6

7

8

9

10

11

Parameter
2,4-DNT
2,6-ONT
2, 4-0 NT
2,6-ONT
2,4-DNT
2,6-ONT
2,4-DNT
2,6-DNT
ฃ,4-DNT
2,6-ONT
2,4-ONT
2,6-DNT
2,4-ONT
2,6-DNT
2,4-DNT
2,6-DNT
2,4-ONT
2,6-ONT
2,4-ONT
2,6-ONT
2,4-ONT
2,6-DNT
Concentration
Well Samole
ND
NO
1.88
3.77
0.017
0.024
0.098
0.356
0.001
0.003
0.306
0.188
0.011
0.083
0.050
0.356
0.004
0.050
ND
ND
ND
ND
Field
Blank
ND
NO
0.014
0.008
0.019
0.013
0.002
0.001
ND
ND
0.001
ND
ND
ND
0.001
0.001
0.002
0.001
ND
ND
0.006
ND
Percent
Variation
0
0
.01
0.2
112.0
54.0
2.0
0.3
0
0
0.3
0
0
0
2.0
0.3
50.0
2.0
0
0.6
0
0
All analyses are  in  mg/L
                                          6-37

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An example  of  probable sample contamination  due to materials of  construction
occurred in 1980.  Nine monitor wells were  installed  at  a  chemical  plant which
produces no chlorinated  products  or  wastes.   Presented below are  the  results
of the analyses for Total Organic Halogen of  water  samples from  the wells.

                     Total Organic Halogen  (ug/1)
         Monitor Well        S1        S2        S3        S4
               1              <10        13
               2               30        21        30
               3               28        25        23        14
               4
               5
               6
               7
10
64
26
34
66
<10
67
40
56
30
<10
56
35
28
21
40
68
75
75
42
The only difference in the nine wells is that wells 1 through 4 were  installed
using screen from a different supplier than wells 5 through 9.   It  is probable
that the  second supplier used  a  chlorinated degreasing solvent to  clean  the
well screens.   Another possible  explanation  for the presence  of  halogenated
organics  in  these wells  is  leaching  of vinyl chloride monomers and  polymers
from the PVC casing itself.

A  third  possibility  for  explaining  the  anomalous  data  is that  there is  a
naturally  occurring background level  of  halogenated  organics in the  ground
water  system.    It  has been  shown  that natural  background  concentrations  of
both chloroform and carbon tetrachloride  are  present in both  the  atmosphere
and  surface  waters.   However, given the  low  concentrations  of  halogenated
organics in both  local  wells  and  in  Monitor Wells  1 through 4, it  is unlikely
that the high levels in Monitor Wells 5 through 9 can be attributed to natural
causes.

Obviously,  another source  for the  presence of  these compounds  in Wells  5
through 9, because  they were  sampled  on a different date  from Wells  1 through
4, is contaminated  sample containers.  The containers may have  inititally been
contaminated or may have become contaminated during sampling.
                                     6-38

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Contamination can  also  be  caused by  sampling  equipment  and  by  components used
during manufacturing  of the sampling devices.   High pressure  liquid  chroma-
tography grade  water  was poured over a fresh pair of gloves while  the gloves
were being worn.   The water was collected  directly  into a 1 liter amber glass
jar, placed on  ice and transported  to the laboratory for analysis.  The sample
was analyzed by GC/MS for phthalates plus any significant peaks.  The analysis
detected 2,6-dimethyl-2,5-heptadiene-4-one  at 5  ppb,   and  isophorone  at  4.9
ppb.  These two compounds were not  detected in equipment blanks of PVC bailers
used  to  sample  the  wells,  trip  or field  blanks,  or  the laboratory  blank.
Based upon the whole of the data, the source of these compounds appeared to be
directly attributable to the surgical gloves.

Another example of contamination caused by  sampling  devices concerned work at
a land treatment  facility  on the Texas Gulf Coast.   Analysis  of water samples
collected from  ground water monitoring  wells located at  the perimeter of the
active portion  of  the Land Treatment Unit measured tetrachoroethylene,  and
1,1,1-trichoroethane  at 13  to  66  ppb in  select samples.   The  samples were
collected using a  dedicated bladder pump.   Previous  to the sampling event that
detected  the compounds,  notification of  pump  contamination   by  chlorinated
hydrocarbons  had  been sent to  owners  by  the manufacturer.  Water  extraction
testing of pump parts by the manufacturer  had  identified  a food grade Teflon
lubricant used during final assembly of the pumps as the source of the chlori-
nated hydrocarbons.

In  order  to  identify whether  or not the  contaminants  detected  at  the Texas
facility were related to  the  pumps, an  in  situ  time  series   sampling  of the
pumps was completed  at the site.  The time  series  sampling consisted of col-
lecting three discrete samples of  water resident in the pump  tubing and body
from  each of two  wells  where  the  contaminants  had  previously been detected,
namely Well A and  Well  B.   Identification  of the sample was based upon calcu-
lated volumes of  water in  the  discharge  hose and the known volume of water in
the pump body itself.   The first collected sample consists of  water which has
been residing in  the  discharge  hose  of  the pumps.  The second  sample approxi-
mately represents  water residing in the body of the pump.  The third sample
represents water  from the  well  sand  pack and the aquifer itself.  Previous to
                                     6-39

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the time  series  sampling,  the  pumps  had  not  been  operated  for approximately 3
months.  Once the three samples had been collected using the bladder pump,  the
pump was  removed and the well was purged using a rigid  PVC  bailer.   A fourth
sample was then  collected for analysis using  a new dedicated PVC bafler.

The  samples  collected  using  the  bladder  pump showed  significant  levels  of
1,1,1-trichloroethane,  tetrachloroethylene and  1,1  dichloroethylene.   Of  the
three  samples  collected  using  the  bladder  pump, the  highest  levels  of  the
compounds  occurred  in  water  which had been residing  within the body  of  the
pump.  Samples  A-4 and B-4, collected using the  PVC bailer after  the bladder
pump was  removed, contained no detectable  (<10  ppb)  levels  of the  chlorinated
hydrocarbons.

Wells  C  and  D  were sampled in the same  manner as Wells A  and  B,  in order to
identify  any  contribution of phthalate  organics  to  collected  samples  by  the
bladder  pump.   The primary organics detected were bis-2-ethylhexyl  phthalate
and 2  ethyl  hexanol.  As with the chlorinated  hydrocarbons, the highest con-
centration of  the  contaminants were in the  sample of  water that was residing
in the body of the pump.  Samples collected subsequent  to removal of the pumps
showed a significant decrease or absence of the organics.  Detection of bis-2-
ethylhexyl phthalate was attributed to laboratory contaminants.

6.2.8  Physical  and Chemical Concerns
Interpreting the results  from  a  sampling event  also  requires a  thorough know-
ledge  of  the  lithology of the aquifer,  the  directions and  velocity of ground
water  flow and  the spatial, temporal and chemical variations  of ground water
quality.   This  section gives examples of ways  in which these characteristics
can affect conclusions on analytical results.

The  lithology  of  uppermost sediments  along  the southern  Gulf Coast  of  the
United States  consists of  interbedded,  discontinuous   strata of interdeltaic
silts, clays, and sands.  In the course of  monitoring a hazardous waste facil-
ity,  one well  may be  within the  facility  monitoring  system  screened in  a
coarse  sand  and  another  well  in  the  same  monitoring  system  screened in  a
clayey sand, where  both wells  monitor  the  uppermost  permeable unit underlying
the Resource Conservation and Recovery Act  (RCRA) regulated facility.   Water
                                     6-40

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samples  collected  from such  wells  have been  shown  to exhibit a  significant
variation in  concentration  of inorganic monitoring parameters as a  result  of
the naturally occurring variations in  lithology of the  permeable zone.   Where
the variations  in  sediments  within a  monitored  zone  include variations  in
carbon content, significant variations may occur in the amount of  adhesion  of
any organic  waste  constituents present  in the monitored  zone to  the  aquifer
sediment.    Furthermore,  where  variations  in lithology  exist,   significant
variations in  seepage  velocities  of  the ground water may occur and  result  in
preferential  flow paths of  monitored species.   Proper  documentation  of  litho-
logic variations within a monitored zone is crucial to  the  correct  interpreta-
tion of sample analytical data.

Variations in the permeability of the aquifer have  been demonstrated  to affect
the quality  of the  ground  water sample  collected from the  monitoring  well.
Wells of  similar construction  and design  screened  in variable lithologies may
exhibit  variations  in  recovery rates subsequent to purging due to the  innate
variations in permeability of the monitored unit.   As a result, the concentra-
tions of monitored species, both organic and  inorganic, may vary between wells
because of variations  in aeration or chemical reduction of the sample  in the
wellbore, which may  occur during  the recovery  period.   For example,  a monitor
well completed  in a  well-sorted coarse  sand  may be sufficiently  purged within
15  minutes;  thus, prompt  collection of a water  sample is  allowed.   On the
other hand, a monitor  well  that  is  completed in a  sandy silt  may  take several
hours  to recover sufficient  water  to  collect  a sample.   Where the recovery
rate  of  a well  is  believed  to  affect water  quality  results, the  suspected
influence  should  be  verified by  sampling  the slowly  recovering  well.  The
degree of influence  may  then  be more or less quantified and considered in  the
overall  interpretation of the water quality data.

The occurrence  of  vertical  gradients of flow  between  permeable  strata within
an aquifer system, if  not properly accounted  for,  may result in the monitoring
of  water quality in multiple zones within  one well.   The  upper aquifer  is
contaminated,  but  the  lower  aquifer  is  not.  Under  static  conditions,  the
lower aquifer has a  higher  hydraulic head than the  upper aquifer,  and vertical
cross  flow  in the well  occurs from the  lower aquifer to the upper aquifer.
Assuming  that the  transmissivities of  the  aquifers are 2,000  gallons/day/foot
                                     6-41

-------
and the storage  coefficient  is 0.0003, over 40  days  of  pumping this well  at a
rate of  15 gallons/minute would be  required  before  a sample  of  the  contami-
nated  water in  the upper  aquifer  could be  obtained.   To  avoid  cross  flow
between permeable strata, the screen section  of  any one  monitoring well  should
be set to  monitor  one  discrete permeable  stratum.  Identification of vertical
components of flow  in  the  aquifer system  can  be made with  clustered or  nested
wells, which are a group of wells installed  in the same  immediate  vicinity and
screened at variable depths.

In addition  to defining the  hydraulic characteristics,  the  chemistry  of  the
monitored  zone(s)  should be  thoroughly  defined prior to  interpreting  sample
analytical  data  obtained as  part of  a  RCRA  monitoring  program.   A naturally
occurring  spatial  variation  in  the  salinity  of  connate  waters   is  commonly
found along the Texas Gulf Coast.  During the coarse  of  monitoring a regulated
waste facility in the Gulf Coast area, total  dissolved solids were measured at
30,000 mg/1  in  one well.  Water quality  in wells  located  at  the  other  end of
the facility  showed total  dissolved solids  of  approximately  500  to 800 mg/L.
On the  basis of  a statistical  comparison of the concentrations  of  chromium
between wells, the  well  yielding saline-quality water was  interpreted to  have
been  affected by  the  waste  management   unit.   Monitoring  wells  were  later
installed  at points between the  freshwater and saline wells.   A measurement of
specific cations and anions, total  dissolved  solids,  and specific  conductivity
revealed a  clear  spatial  trend from  freshwater  to  saline-quality  water  in the
region, in contrast to any plume of  contamination originating from the waste
management unit.

The degree of alteration  in  the chemistry  of  the ground  water sample  during
sample collection (e.g., oxidation,  precipitation,  and adsorption)  has  been
shown  to  be  influenced  by the  initial chemistry  of the  ground  water  (e.g.,
initial Eh,  pH,  redox  buffering capacity, and  pH buffering  capacity,  and pH
buffering  capacity).   Through laboratory simulation of sampling   from  a  very
shallow water table  (less  than 18  feet below ground),  the  amount of  iron
precipitation due  to aeration of the  sample  during collection has been  demon-
strated to be significantly reduced in waters with a  lower  initial pH.  Mixing
of well  water with  the atmosphere  causes aeration  and oxidation  of ferrous
iron to ferric  iron.   Ferric  iron rapidly precipitates  as iron hydroxide and
                                     6-42

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can adsorb other monitoring constituents including  arsenic,  cadmium,  lead,  and
vanadium.   Therefore,  aside from the amount  of  aeration that may occur as  a
result of  the sample collection procedure,  the  amount of  iron  precipitation
resulting  from aeration  is  dependent  upon the  innate  quality of the  ground
water.

In  addition to  considering  the hydrologic  and  geochemical  controls of  the
aquifer  upon  the  ground  water  sample, the  flow  behavior  of the  monitored
species  should  be  taken  into  consideration  when  designing  the  monitoring
well.   Figure 6-6 shows  a cross section of a surface  impoundment  containing
soluble salts.  As indicated by chemical analysis of  ground  water from shallow
and  deep  cluster  wells,   the  flow  of  leachate  originating from the  surface
impoundment  was  concentrated along  the  bottom of  the aquifer because  of  the
greater  density  of  the  leachate relative  to the density  of the  unaffected
ground waters.  Without consideration of the flow behavior of the leachate  and
without investigation of  the vertical extent  of  the  aquifer,  the contaminants
may have gone  undetected.
                                     6-43

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        MW-1  MW-2
          JL    JL
K31 x  10-2
 cm./sec.
                      Approximate Boundary of
                      Surface Impoundment used
                      for Disposal of Soluble Salts
                                                 o MW-7
Fine """   -y	
Silty     4
Saiid.r

    ^         Leacnate with
            Specific Gravity >1.0
                             Stiff Clay
                       K 31 x 10-6 cm./sec.
                                       Zone of
                                    Gravimetric
                                     Separation
                    Total Dissolved Solids content
                    of samples from monitor wells
WELL
MW-1
MW-2
MW-7
MW-8
MW-9
MW-10
DEPTH
45
25
48
30
30
48
TDS
830
450
95.000
4,300
3,900
78,000
         PLAN VIEW
             MW-1
 Approximate
 Boundary of
 Abandoned
 Disposal Site
                                      MW-4
                        MW-12 MW-11
  '/MW-9

MVV-10
                                           Explanation
                                           Monitor V/ell
                                           •Direction of
                                           Ground Water
                                           Flow
             Figure 6-6.  Flow Behavior of Leachate from  a
                          Surface  Impoundment
                                  6-44

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7.0  GROUND WATER MODELING

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                          7.0  GROUND WATER MODELING

In general  terms,  a model  can  be described as a simplification, or  abstrac-
tion, of the  complex physical reality and  the  processes  in  it  (Bear 1979).   A
model of  ground water contamination may  consist  of contours on a  map  repre-
senting  lines  of  equal  concentration of  chloride in  the  monitored  zone,  or a
three dimensional  picture of contaminant  plume migration, taking  into account
adsorption and  radioactive decay of the  monitored  species.

Modeling ground water contamination  is  just one application  of  one type  of
ground  water  model.   There are  four  general  types  of  ground water  models.
They are prediction  models  which simulate the response of  the  flow system  to
stress; resource management models  which  integrate  hydrologic  prediction  with
management  decision;  identification models  which  determine input  parameters
for  both  of  the   above;  and  data  manipulation and storage procedures  which
process and manage input data for all of  the above.  Prediction models may  be
subdivided  into four  major categories:    flow,  and  mass  transport  models,
described  below;   subsidence models  used  to describe  the phenomenon of  land
subsidence  resulting  from  ground  water  withdrawal, and   heat  transport  which
couples the  flow  of heat with  water or steam for  problems where thermal  ef-
fects are important, i.e. storage of nuclear waste,  geothermal  reservoirs.

Modeling of ground water contamination  consists of  solving  mathematical  equa-
tions described by flow  and mass  transport type predictive  models.   Following
is a brief  overview of  the  flow  and  mass transport models,  the method  of
mathematical  solution of the models, and  general guidelines  for applying  such
models.

7.1  FLOW MODELS
Flow  models  are   utilized  to  solve  partial  differential  equations  used  to
quantify aspects   of ground water flow including change  in water  level,  the
direction  and rate of  flow,  stream-aquifer interaction  and  interference  ef-
fects of production wells.  The  models  together with  appropriate  boundary and
intial  conditions  express  conservation of mass,  momentum,  and energy.   The
basic rule of conservation  for the fluid in the volume of aquifer  is:
                                      7-1

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    rate of change of       rate of flow of      rate of flow of
    mass of fluid in    =   fluid mass into  -   fluid mass out
    a volume with time      the volume           of the volume

In order  to solve  the equations  describing  ground  water flow  the  following
elements must be completely described:

          1. The distribution of the  parameters through the  space of
             interest,
          2. Initial conditions for fluid  pressure,  composition, and
             temperature,
          3. The  sources  and  sinks of  interest  and  their variation
             with time, and
          4. The  boundary  conditions  at  the margins  of the  space of
             interest.
There are two widely used methods of solution of flow models -- the analytical
and numerical method.  The analytical method utilizes functional relationships
which  can  be  expressed  in  closed  form  with  fixed  parameters.   Analytical
solutions to problems of ground water flow are generally  applied to uniformly
porous aquifers and aquitards which are homogeneous, infinite in area! extent,
and of  the same  thickness throughout.   Except in the case  of  flowing wells,
the discharge  or recharge of  production  or injection wells  is  assumed  to be
constant.   Both fully and partially penetrating wells are considered.

Numerical models  approximate  partial  differential  equations describing ground
water flow  for each node of  a  grid designed over the aquifer  area of inter-
est.   All   nodes  are  combined to form a  matrix equation.   The numerical ap-
proach computes new values of the variables involved (head potentials) at each
node, for each time step adopted.

Because of  the  large  number  of  calculations involved,  numerical models employ
computer capability.   By 1977 about 200  predictive  numerical  computer models
had been  developed  throughout the world  (Walton,  1984).   69 percent of these
models are  flow models  and  19 percent  are mass transport models.  One example
is  the  Prickett  Lonquist Aquifer Simulation Model  (PLASM),  which  models non-
steady  state two dimensional  flow in a heterogeneous,  isotropic,  artesian
ground water system with internal sources and sinks.
                                      7-2

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Ground  water  scientists  and  engineers  typically  depend  upon  commercially
generated   software  for ground water  modelling.   Most  computer models  are
written  in   BASIC or  FORTRAN.  Software is available  for purchase at  minimum
cost ($50.00 to $5,000.00) for both micro and mainframe  computers.  The Inter-
national Ground  Water Modeling Center  (IGWMC) associated with  Butler  Univer-
sity  in Indianapolis,  Indiana,  serves  as an informational clearinghouse  for
ground water modeling software.

7.2  MASS TRANSPORT MODELS
The mass transport model is used to describe the  spread  of mass in the  subsur-
face under the  influence of  physical, chemical and  biological  processes.   The
model has, as its basis, the conservation of a chemical  species.  The equation
may be written in words  as

    the rate of          the rate of transport       the net rate at
    change of mass   =   of mass into and out   +/-   which species
    of  species A         of the system               A is produced
    in  a volume                                      in  the volume
    with time                                       by  chemical
                                                    reaction.

As  shown  in  the  equation,  the mass transport model contains  a flow submodel
which  provides  flow  direction  and velocities.   The  submodel   utilizes  these
velocities to simulate  adyective transport,  allowing  for  dispersion.   Methods
of  transformation of the  solute include  adsorption,  biodegradation,  radioac-
tive decay, and ion exchange.

Analytical solutions to  mass transport simulate advection and dispersions from
a solute injection well  in uniformly  porous,  non-leaky  artesian aquifer which
is homogeneous, isotropic, and infinite in area!  extent.  The models  are based
on  assumptions  of one  dimensional  flow and dispersion  in  one,  two,  or three
dimensions.   (Ogata  and Banks,  1961;  Wilson  and  Miller,  1978;  Domenico  and
Robbins, 1985, respectively).

There are serious limitations  associated  with the numerical methods  for solu-
tion of mass  transport  equations,  including overshoot,  undershoot and numeri-
cal dispersion, especially when  transport is  dominated  by advection  (Hitchon,

                                      7-3

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Trudell,  1985).   In most  applications  these  probelms are manageable  through
appropriate modifications to the grid or through algorithmic  treatment  of high
gradients at the fronts of plumes*

7.3  GUIDELINES TO CHOOSING AND USING A MODEL
In deciding whether or not to employ a model,  it should be decided whether the
model  is  necessary to  the field study, and  what  level  of  sophistication  of
modeling is required.

Applying a  model  to a field site can be useful  in  several ways.   Application
of a  model  gives  the  hydrogeologist a perspective  as to what processes  are
important  in  the  flow  and/or  mass  transport.  Modeling provides a  precise
framework for the kinds of measurement which need to be made.  Where there are
complex and  multiple interacting effects,  the  model  serves  to integrate  the
field data.

Modeling,  depending upon  the  level  of  complexity, can  be  a  time  expensive
endeavor.   There are several  steps  in  completing  a model:   1) definition  of
the problem to  be  addressed; 2)  accumulation  of the data base; 3) design of a
conceptual  model;  4)  formulation of  the  model; 5) programming the  model;  6)
specification of  the dimensions, internal   parameters, along with the  initial
conditions  and  boundary  conditions;  7)  testing the sensitivity of the model;
8) calibration of the model; 9) design and execution of simulation experiments
directed toward solution  of  the problem;  10)  analysis  of simulation data; and
11) conclusions.  Though modelling today is well aided by computer brainpower,
there  are  time  outlays  involved in testing .and   calibrating  the model  and
documenting the assumptions and  limitations of the  model.

Once it has been  decided  to  employ  a model, the required level of sophistica-
tion should  be  decided.   Model  input may  include  the  following:   the  geology
of the  system including  geometry and lithologic composistion  of the  strata,
the  aquifer characteristics including  the piezometric  surface through  time,
hydraulic conductivity,  porosity, dispersivity, leakage,  historical  and pro-
jected  pumpage;  knowledge of  surface  water  features  including stream  and
reservoir  elevations,  precipitation,  evapotranspiration;   knowledge  of  the
chemical  and  biological  behavior of the   solute  species  in the  flow system
                                      7-4

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including the  degree  of adsorption,  and biodegration of the  chemical  species
in the flow system.

The ground  water model  is  only as  good  as the data  used  in the model;  the
sophistication of the model  should not  exceed the  reliability and  accuracy of
the data.  Adequate acknowledgement  of  data base  limitations  should  accompany
every completed  simulation.   Most models  are  easily simplified to  take  into
account fewer variables in the system.

Alternatively,  the  model  should  incorporate  all   available  data  on  the
physical/chemical system.  All known boundary conditions must  be accounted for
in the flow model.  The mechanisms  of  chemical  transformation of the contami-
nant must  be  identified  in  the  mass transport model.   The geology,  observed
patterns of flow, and  the distribution  of  contaminants  should fit  together to
form a consistent hydrogeologic picture.

7.4  USE OF MODELS IN CONTAMINATION STUDIES
Contamination  studies   in themselves  can  range  from the  simple to  the  com-
plex.  Contamination from small ponds and lagoons or landfills where  the water
table  is  very shallow  (less  than  25 to 35 feet)  generally  gain  very little
from the initial use of modeling.  That is, if the question is how far has the
waste migrated vertically and/or horizontally, the answer  can be best derived
from field  studies such  as  installing monitoring  wells.   Once the  zone of
contamination  has  been defined, models may become useful  depending  upon the
solution proposed  to  the problem.   For instance,  if  any industry  proposed to
do nothing about a contaminated  plume  by  claiming  that the contaminants would
be diluted by  the  time it reached a pumping water well, then the  use of some
type of  model would  be advisable.   Several  such  models would  be advisable.
Several such models are readily available.  If, however, the contaminant is to
be enclosed by a slurry wall, then modeling may not be necessary or desirable.

If a  recovery program  is proposed,  a  model may  be used to give some initial
indication of  the  number of  wells  required and the  length of  time  they may
require.   However, the better  approach  here would  be to  track the volume
recovered and  the  water  levels  to  determine if the  recovery  system was per-
forming as predicted.  A model is not necessary to do this.
                                      7-5

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Models  are  most useful when the underlying geology  is  very  complex.   In many
Gulf  Coast  areas,  there  are  multiple  sands  and  clays underlying  disposal
sites.   In  these  areas, where  the  contamination has migrated  into  multiple
layers, modeling may be  required and may result in substantial savings.

Models  are  also useful  when  large  areas of aquifers have been  impacted.   If
sufficient geologic and  hydrologic data can be developed for the model, future
monitor  well  locations  can  be predicted  and  different recovery  scenerios
developed.

•7.5  AVAILABILITY OF MODELS
Numerous ground water models are commercially available  for  use on most com-
puters.   Many  early  models were  developed to  run  on main  frame  computers,
although today  most models  can  be  run on IBM PC, XT or AT and compatibles and
many are available for Macintosh systems.
                                      7-6

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8.0  BIBLIOGRAPHY

-------
                               8.0  BIBLIOGRAPHY
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Stolzenburg,  T.  R.;  Nichols,  D.  G., Proceedings 6th  National Symposium  on
Aquifer Restoration  and Ground Water Monitoring, 1986, p. 216.

Subbaraju, B.  H.,  et al.  (1973),  "Field  Performance  of  Drain Wells Designed
Expressly for Strength  Gain  in  Soft  Marine Clays,"  Proc.. 8th  Int. Conf. Soil
Mech. and Found. Engr., Vol. 2.2, Moscow,  pp. 217-220.

Telford, W.  M.,  L.  P. Geldard, R. E.  Sheriff,  and  D. A.  Keys, 1976, "Applied
Geophysics," Cambridge University Press, London.

Terzaghi,  Charles  (1926),   "Simplified  Soil   Tests   for  Subgrades  and  their
Physical Significance", Public Roads, Vol. 7, No.  8.

Terzaghi,  Charles   (1927),  "Principals  of  Final  Soil  Classification," Public
Roads, Vol. 8, No.  3.


                                      8-4

-------
Todd,  D.  T.,  1959,  Ground-water  Hydrology:   New York,  John Wiley and  Sons,
Inc., 336 p.

Todd,  D.  T., 1980, Ground-water  hydrology:   New York,  John Wilson and  Sons,
1980, 2nd ed.

Tsien, S. I.,  "Stabilization of Marsh Deposit,"  Highway  Research Board,  Bull.
115, 1955, pp. 15-43.

Underground  Resource Management,  Inc.,  et  al., 1986,  "Phase  1  Feasibility
Study  for  the Development of Ground  Water  for  Irrigation  in the  Chisumbanje
Area," for the Regional Water Authority,  Zimbabwe, Africa,

U.S.  Department  of  Agriculture,  1969,   SCS National  Engineering Handbook,
Section 18, Ground-water.

U.S.  Department  of  the  Interior, 1974,  Earth  Manual,  U.  S.  Govt.  Printing
Office, 810 p.

U.S. Department  of the Interior (1974),  Earth Manual. Bureau of  Reclamation,
Denver, Colorado.

U.S. Department  of the Interior,  1977, Groundwater Manual,  U. S.  Govt.  Print-
ing Office, 480  p.

U.S. Department  of the Interior,  1978,  Drainage Manual, U.  S. Govt.  Printing
Office, 286 p.

U.S. Environmental  Protection Agency, 1977,  Procedures Manual for  Groundwater
Monitoring at Solid Waste Disposal Facilities.

U.S.  Environmental Protection  Agency,  1978, Surface  Impoundments and  their
effects on Ground-water  Quality in the  United States -  a  Preliminary Survey,
275 p.

U.S. Environmental  Protection Agency, 1982,  Test Methods for Evaluating  Solid
Waste, 2nd ed.

U.S. Environmental  Protection Agency, 1986,  Permit Guidance Manual  on Unsatu-
rated Zone Monitoring  for  Hazardous Waste Land Treatment Units,  U.S.  Environ-
mental Protection  Agency, EPA/530-SW-86-040.

U.S.  Environmental Protection Agency, 40 Code  of  Federal  Regulations  (CFR),
Part 264,  Subpart  M, published  by Bureau of  National  Affairs,  Inc.,  Washing-
ton, D.C.

U. S. Geological Survey,  1976, Guidelines for Collection  and Field  Analysis of
Ground Water Samples for Selected Unstable Constituents,  Book 1,  Chapter D-2.

U.  S.  Geological  Survey,  1984,  National Water  Summary:    Hydrologic Events,
Selected Water Quality Trends,  and Ground Water Resources,  USGS Water  Supply
Paper No. 2275,  467 pp.
                                     8-5

-------
Utah  Water Research  Laboratory,  1986,  Permit Guidance  Manual  on  Hazardous
Waste Land Treatment Demonstrations,  U.S.  Environmental  Protection  Agency.

Verschueren,  K.,  1983, Handbook of  Environmental  Data  on Organic  Chemicals,
Van Nostrand Reinold Company, Inc.,  New York,  New York.

Walton, W. C.,  1970, Ground-water resource evaluation:  New York,  McGraw-Hill
Book Co., 664 p.

Walton, W.  C.,  1960,  "Leaky Artesian  Aquifer Conditions  in Illinois,"  1960,
State Water Survey Report, Invest.  39,  Urabana, Illinois,,

Walton, William C., 1984, "Practical  Aspects  of Groundwater  Modeling",  Nation-
al Water Well Association.

Wilkinson, W. B. (1969), Discussion,  In Situ  Investigation in Soils and Rocks,
British Geot. Soc., Instn. of Civil  Engrs.,  London, pp.  311-313.

Windholz, M., Budavari, S., Stroumtsos, L.,  Fertry, M.s  1976, The Merck Index,
Merck and Company, Inc., Rahway, New Jersey,  9856 p.

Wood, Eric  F.,  Raymond A.  Ferrara,  William  G. Gray, George F.  Pinder,  1984,
"Groundwater  Contamination  From Hazardous Wastes",  Princeton University  Water
Resources Program, Prentice-Hall,  Inc., Englewood Cliffs,  New Jersey.

Wu,  T.  H., Chang, N.  Y.,  and  E.  M. Ali  (1978),  "Consolidation and Strength
Properties of  a Clay," Jour. Geot.  Enqr. Div..  ASCE,  Vol.  104, No. GT7,  pp.
899-905.978), "Consolidation and  Strength  Properties of a Clay,"  Jour.  Geot.
Enqr. Div., ASCE, Vol. 104, No.  GT7,  pp. 899-905.

Yates,  M.  V.,  C. P.  Gerba, and  L.  M.  Kelly,  1985,  "Virus  Persistence  in
Groundwater," Applied  and Environmental Microbiology, Vol. 49,  No.  4.
                                     8-6

-------
           GROUND WATER CONTAMINATION STUDIES
                  OCTOBER 26, 27, 28, 1987
                         Dallas,  Texas
Monday. October 26.  1987                                  Instructor

 8:00 -  8:30   Registration  and  Introduction
 8:30 -  9:00   "Wellhead Protection Requirements"         R. Kent
 9:00 - 10:15   "Introduction  to Ground  Water Hydrology"     R. Kent
10:15 - 10:30   Break
10:30 - 11:30   "Investigative Techniques  for Ground  Water  E. Fendley
                Contaminations  Studies"
11:30 -  1:00   Lunch
 1:00 -  2:00   "Ground Water Monitoring Systems Design    E. Fendley
                and  Installation"
 2:00 -  2:15   Break
 2:15 -  3:15   "Ground Water Sampling Techniques"         M.  Katterjohn
 3:15 -  3:30   Break
 3:30 -  4:30   "Ground Water Flow and Aquifer             M.  Katterjohn
                Characterization"
 4:30 -  5:00   "Practical Approaches to Ground Water       M.  Katterjohn
                Contamination Studies"
 5:00           Adjourn for  Day
Tuesday. October 27.  1987

 8:00 -  8:30   Leave for Field Site
 8:30 - 10:00   Demonstration  of Drilling and Soil Sampling Techniques
                Hollow Stem Auger
10:00  -10:30   Slug Test Set-Up
10:30 -  Noon   Demonstration  of Mud Rotary Drilling,  Monitor Well
                Installation, and Grouting
 Noon -  1:00   Lunch
 1:00 -  2:00   Slug Test Demonstration
 2:00 -  3:30   Sampling  Demonstration
 3:30 -  4:00   Return to Classroom
 4:00 -  4:30   Field Demonstration  Overview -  Question  and  Answer
 4:30           Adjourn  for Day

-------
Wednesday. October 28. 1987                                Instructor

 8:00 -   8:30   Coffee
 8:30 -   9:30   "Ground Water Chemistry and Significance    R. Kent
                of Organic and Inorganic Constituents in
                Ground Water"
 9:30 - 10:00   Break
10:00 - 10:45   "Ground Water Contamination Studies Data    R. Kent
                Analysis  and Evaluation"
10:45 - 11:30   "Practical  Problems  in Ground Water         M.  Katterjohn
                Contamination Studies"
11:30 -   1:00.   Lunch
 1:00 -   2:30   "Designing a Ground Water  Contamination     All
                Study"
 2:30 -   3:00   Break
 3:00 -   4:00   "Designing a Ground Water  Contamination     All
                Study"
 4:00           Course Critique

-------
             GROUND WATER CONTAMINATION STUDIES
              OCTOBER 26-28, 1987 DALLAS, TEXAS
                       COURSE CRITIQUE

COURSE         EXCELLENT           AVERAGE        VERY POOR
RATINGS:             10   987654321
MEETING ROOM FACILITIES:     10987654321

AUDIO/VISUAL AIDS:          10 987654321

COURSE MANUAL CONTENT:     10987654321

LECTURE CONTENT:           10987654321


COMMENTS:

WHAT DID YOU LIKE ABOUT THIS COURSE ?
WHAT DID YOU LEARN FROM THIS COURSE WHICH WILL BE USEFUL TO YOU IN THE FUTURE ?
WHAT DID YOU NOT LIKE ABOUT THE COURSE ?
SUGGESTIONS ON WAYS TO IMPROVE THIS COURSE AND/OR GENERAL COMMENTS ?

-------

-------
                                CLASS PROBLEMS
1.   Using Figures  1  and  2 and the well construction  information  in  Table  1,
     construct a water table contour map and  determine  the direction of ground
     water flow.

2.   Using the  information in  the  text book,  the  graph paper provided,  the
     slug test data from Table 2, and the monitor well  construction diagram of
     Figure 3, calculate the hydraulic conductivity  (using the  Bouwer and Rice
     Method)  of the formation  in gpd/ft, cm/sec  and  ft/day,  assuming  the base
     of the aquifer corresponds with the base of the well, (i.e.,  h = D).

3.   Using the  calculated  hydraulic conductivity and  the water table contour
     map calculated in  Item 1,  calculate the  rate of apparent  movement in the
     aquifer.

4.   Using the information contained in 1,  2  and 3 above, what  volume of water
     is moving underneath  the  pond  in  Figure  1,  assuming the pond is 200 feet
     wide  and  400  feet  long?   What  affect  will   this volume  have on  any
     potential leakage from the impoundment?

5.   A  shut-down  refinery  along  the  Gulf  Coast  has  a  series  of  waste
     treatment/disposal facilities.  Figure 4 shows  the plant map.  The owners
     are concerned that their two disposal  sites, a  landfarm and a waste water
     treatment  lagoon, may  be  impacting  the  ground  water.    Only  limited
     chemical  analysis is  available  for  the  landfarm  or  lagoon  (Table  3).
     There are no existing monitor  wells and  only a limited number of on-site
     soil borings  (attached).   The plant asked you  to design  and carry out a
     ground  water  investigation  to  determine   if  the  facility   is  leaking.
     Prepare an investigative plan for conducting the  investigation.

-------
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-------
                  TABLE 2
       Slug Test #1 of Monitor Well MW-7
Project Name
Project Number
Test Date
Well Number
Casing Radius
Static Water Level - BTOC
Test Start - 17:10

    Time
  (seconds)

    1 5
    25
    45
    65
    85
    105
    135
    155
    195
    225
    255
    285
    315
    345
    375
    41 0
    450
    495
    520
    555
    645
    735
    820
    915
    1215
BTOC
Water Level
(feet below top
of casing)
23.06
22.66
22.38
22.28
22.20
22.15
22.06
22.00
21.93
21.87
21.84
21.78
21.75
21.73
21.70
21.68
21.65
21.63
21.62
21.61
21.59
21.58
21.57
21.56
21.55
GenFac, USA
100-01 1
April 30 1987
Monitor Well MW-7
.17 feet
21.54 feet
Test End - 17:30
Y(t)
(feet)

1.52
1.12
0.84
0.74
0.66
0.61
0.52
0.46
0.39
0.33
0.30
0.24
0.21
0.19
0.16
0.14
0.11
0.09
0.08
0.07
0.05
0.04
0.03
0.02
0.01

-------
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Filter Sand
PVC
 Clay
               FIGURE 3
MONITOR WELL MW-7 CONSTRUCTION DIAGRAM
        BAILER PERMEABILITY TEST

-------
                           FIGURE 4
  X
 B-1
     f
PROPERTY LINE
                       LAND
                     TREATMENT
                        UNIT
                                                   X
                                                  B-7
ROADS








X
TANK B-6
FARM










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FARM













ROADS
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                                    ROADS


OFFICE
X

                           B-8
                            PARKING
                                    ROADS
 T
GATE
SCALE  (ft)
                                         0
     I       I
   100    200

-------
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-------
                        BORING LOG


                  BORING NO.   B-l


                  DATE DRILLED  7/2/75

                  TOTAL DEPTH    45'

                  SURFACE ELEVATION   64.2'
                      Description of Stratum
 5 -5
10
Topsoil
CLAY, slightly silty, slightly calcareous,
 dark gray, moist (CH)
CLAY, silty, slightly calcareous, light
 gray, moist (CL)
 -very calcareous, very silty, trace of
   sand, wet
             CLAYEY SAND, fine to medium, 30% clay,
              light gray, saturated (SC)	
             CLAY, stiff, iron-stained, tan with black,
             ~moTst (CH)
             CLAY, 30% fine sand, calcareous, light
              gray, saturated (CL)
             SAND, fine to medium, 10ซ clay, black and
            \tan, saturated (SP/SC)	
             CLAY, stiff, iron-stained, oxidized roots,
              tan, moist (CH)
              -very stiff @ 29'	
             CLAYEY SAND, fine to medium, 45% clay,
              gray, wet (SC)
              -30% clay (a 40 ft.
             CLAY, stiff, calcareous, light brown,
              moist (CH)       	
                             T.D. 45'

-------
                        BORING LOG


                  BORING NO.    B-2

                  DATE DRILLED   7/2/75


                  TOTAL DEPTH   40'


                  SURFACE ELEVATION  54.4'
          >-
          CO
                          DESCRIPTION  OF  STRATUM
6



9



12



15



18



21
          CH
          CL
          ML
          CH
      Clay,  slightly organic,  dark gray, moist.


      Clay,  very calcareous,  slightly silty, light
       tan,  moist

      Wet
      Silt, clayey,  20%  fine-grained  sand, light
       tan, saturated

      Clay, slightly silty,  trace of  calcareous
       nodules, red/tan, moist
 24


 27
     Tan and gray
30
33
SC   Sand, clayey, 60% fine to medium-grained,
      light tan, saturated
36



39



42
CL   Clay, sandy, light tan, moist
                     T.D. 40'

-------
                                BORING LOG


                           BORING NO.   B-3

                           DATE DRILLED    7/7/75


                           TOTAL DEPTH     50'

                           SURFACE ELEVATION    58.9'
   a
   a
  a
        o
        .a
            c.
            a
                             Sample  Description
 5 -
       CH
                 5ILTY CUY.  highly plastic, 5-lOt very f1nซ sand, 35-451  fines,
                   firm, very moist, grey mottled  with white and black,  very
                   strong reaction HC1. odor, gooey	
 10 -4
       SP   "is    SAND, poorly graded, f1nซ to very fine, 0-101 fines, loose,
                   saturated, tan to grey, very strong odor
 15 -
 20 —
       CL  HHS   5ILTY CUY.  moderately plastic,  5-15X very fine sand,  20-301
                   silt, stiff, moist-damp, tan to  grey, very strong reaction
                   to HC1.  odnr	
       CH
       CH
30 —
       CH

                 CUY. highly plastic, 0-lOt very fine sand, stiff, moist,  tan,
                   very strong reaction HC1, odor
                 CUY. similar to above, except  very stiff, no odor
                 CUY. similar to above except mottled tan and very light  green
35 -
40 -
45 —
       CH
       CH
       CL
    P
                 SANDY CUY.  highly plastic, 15-25J very fine sand, firm (cru*.
                   bles), moist, grey, moderate  reaction to HC1
                 SANDY CUY.  similar to above  except 30-40t very fine sand,
                   stiff,  strong reaction to HC1
                 SANDY CUY, similar to above,  except sllghtly-moderately
                   plastic, 40-501 very fine sand, very moist
50 -
SP/
CH
          1
 SAND i SANDY  CUY  LAYERS-

   SAND, poorly graded,  fine to very fine.  0-51  fines, loose.
     moist, tan to grey, slight reaction to HC1
I   SANDY CLAY, similar  to above, except varying  plasticity and/
\    sandy content ^hrouohout                   	I
             iotal  ueoth at 50 ft.

-------
    BORING LOG



BORING NO.   B-4



DATE DRILLED   7/8/75



TOTAL DEPTH   46'



SURFACE ELEVATION   56.4'
-C
a
0
a
t
-
_
5 -
"j
15 —
_
20-
25 —
-
30 —
J
-1
— 1
J
45 —
-
50 _
j
~~;
"o
.a
1
i'
•I
1
CH 'f
1
"\
y
MH

CH ^
CH V
\
t.
sw '••:•:


c
a
a
a Samole Description
•3
7>
0 Oik
H 4
\
/ CLAY, soorly graded, 10-151 silt, 30X clay, very plastic, hard
/, Tpp-3.5). saturated, tan color, root mottles
A SIL7Y CLAY, poorly graded, 10-151 fine sand. 30-35? silt, SOS
ty clay, some minor caliche, very highly plastic, very Hard
^ (pp ซ.5), saturated, tan matrix with areas of red reduction,
y| wnlte caliche and black organics. root mottles, worn burrows
/. SANOY CLAY, poorly graded, 20-30S fine sand, 10-20^ silt,
'/ 50", cUy, minor caliche, highly oiastic, hard (pp-3.0),
A saturated, same color >.s samole ?t 10' . root nnttlps
f
: SAHOY SILT, soorly graded, 5-101 medium sand, 20-30* fine sand,
i JO--OJ siit, 10-151 clay, hignly oiastic. hard (ppซ3.0),
! saturated, tan matrix, black organic spots
] SANOY CLAYEY SILT. ;oorly graded. 23-lQr, fins to mปdi,,.-n 5;1nH,
1 50; snt, lO-JO^ clay, hignly oiastic. hard (pp*3.3),
' saturated, tan with black organic spots, good ripple develop-
ment
/
/ CLAY, poorly graded, 5-151 fine sand, 70-80X clay, highly
',, plastic, hard (pp-3.5), saturated, tan matrix, red reduction
/ spots, black organics, ripples, root mottles
A
/
', CLAY, same as sample at 30'
A
A
/
/ SANDY CLAY, poorly graded, 20-30J fine sand, 50-60* clay, 10S
/ organtcs, hignly plastic, hard (pp-3.0), saturated, tan
..;i SANO, well graded. 20-251 medium arained. 60-70! Hn. nr.in.H
i \ sard, in.isi clay or silt, non-olast1c, comoact, saturated /
! \ tan /
| Total Depth at 16'

-------
                 BORING LOG

             BORING NO.   B-5

             DATE DRILLED   7/8/75


             TOTAL DEPTH    38'


             SURFACE ELEVATION   49.6'
 >•
 CO
                 DESCRIPTION  OF  STRATUM
9



12.


15



18



21


24



27



30.



33_


36.


39
CH/
CL
SM
CH
SC
CL
      Clay, slightly organic, slightly silty, dark
       brown, moist
      Slightly calcareous
      Sand, silty, slightly clayey, 60% fine to
       medium-grained, light gray, saturated
      Clay, slightly calcareous, red/tan, moist
      Stiff, light tan with gray
      Highly calcareous
      Sand, silty, clayey, 60% fine-grained, light
       tan, wet
      Saturated
      Clay, calcareous, sandy, light tan, wet

                     T.D. 38'

-------
     BORING LOG
BORING NO.    B-6
DATE DRILLED   7/27/76
TOTAL DEPTH   50*
SURFACE ELEVATION
ฃ
a
o
O

5-
-
_
10-



~
15-
20—

.
25—

_
30—
35—

-
_
40—
-
—
45 —


—
"o
a
CO

CL



SP



sc

CL


CH

SP

CL


CL


CL
SP


JC
a
ia
w
a
a
CO
1
^
•*/•'.-

•::•:


M
1


\
/
•
>\
1
1
^
ft
fy
//

'/
/
'/,



Sample Description


CLAY, moderately plastic. 2-3% f1nซ sand, stiff, moist, red
with black dendrltes, root mottles, no odor


SANO, poorly graded, mostly fine sand. 1-3X fines, very lonte.
saturated, tan to buff, silts In partings, root mottles, no
ndnr*

CLAYEY SAND, similar to above only 1% caliche gravel and
5-81 fines

SANDY CLAY, moderately plastic. 1-2X caliche gravel. 10-151
fine sand, tan to reddish brown, root mottles, no odor

S.ILTY.CLAY, similar to above only no sand and Is highly
"plastic
CLAYEY SANO. poorly graded, mostly fine sand, 201 fines, com-
pact, saturated, buff colored, root mottles, clay partings.

CLAY, slightly plastic. IS caliche pellets. 1-31 fine sand.
hard, saturated, light green, root mottles, no odor

CLAY, similar to above


CLAY, similar to above
SANO, poorly graded, mostly fine sand, loose, saturated, tan 	
\ to buff, root mottles, no odor /
Total Depth at 50 ft.

-------
                                BORING LOG


                         BORING NO.   B-7

                         DATE DRILLED    3/21/76

                         TOTAL DEPTH    50'


                         SURFACE ELEVATION    59.3'
   a
   o
   a
  o
 a

  >.
 CO
                   Sample Description
  5 -
       SP

          CLAYEY SAMO. poorly graded. 801 mostly  fine sand. 20t  fines,
            stiff (pp-3.0),  damp, tan, dens*,  root mottles, reduction
            spots, no odor
       CH
 10 —
     /
     X
CLAY,  highly plastic,  3-4X very fine sand,  hard (pp  4.5),
  moist,  tan, root mottles, reduction spots, no odor
 IS  —
                 SANO, poorly graded,  971 mostly fine sand. Z-31 fines,  loose,
                   moist, tan, reduction soots, no odor
 20 —
       CL
            X
                 SANOY CLAY, moderately plastic, 301 mostly medium sand,  firm
                   lpp-2.75), moist, tan, reduction spots, sand appears 1n
                   Dockets         	
CL
            X
            /.
            X
         CLAY, moderate plasticity,  Z-31  fine sand, hard  (pp  4.5). moist
           tan, reduction spots
       SC
                CLAYCY SANO.   poorly graded, 601 medlm to fine sand. 40X fines.
                  very dense,  moist, tan, reduction spots, root mottles, no odor
35 -
40 -
45 -
       CH
       CH
       CH
      CH

         CLAY,  high plasticity,  3-4% very fine sand,  dense (pp  4.5).
           saturated, tan, reduction spots, no odor
                CLAY, similar to above
                SANOY CLAY, similar to above only 10-15S mostly fine sand
                CLAY,  similar to above  only 3-4X very fine  sand
                            Total  Depth at 50 ft.

-------
    BORING LOG



BORING NO.   B-8




DATE DRILLED 3/22/76




TOTAL DEPTH   44'




SURFACE ELEVATION   54,5-
.c
Q.
0>
Q

5_
10 -
15
20 -
?C _,

30 -J


35 -
40 -

45 H

-
o
JO
E
>>
(0
\vv
^VO
1
1
Ir
1
r
•x::::::


:|:j:j:j:;




Description of Stratum
Tnncni 1
CLAY, slightly silty, slightly calcareous,
dark gray, moist (CH)
CLAY, silty, calcareous", light gray, moist
ICL)
-very calcareous, small nodules •
-light tan, calcareous, saturated @ 11 ft,
-trace of sand, tan and red, moist
•.cl i nhtl \/ ^al c* A v*ennc
CLAY , firm, slightly silty, large crystals
of calcite, tan with red and black, moist
VlCH/CL)
SILT. 30% clay, 20% very fine sand, light
tan, saturated (ML)
CLAY. 25* silt, 15% very fine sand, cal-
careous, tan and red, moist (CL)
v CLAY, slightly calcareous, tan and red,
\- moist fcfl^

\CLAYEY SAND saturated - no returns (SC)
\uLAY_, 20% very fine sand, abundant crys-
tals and nodules of calcite, gray, moist
(CL/CH)
-moderately stiff
SAND, fine, 30% clay, light tan, satura-
X ted (SC)
\ CLAY, stiff, slightly calcareous, tan and
\ red, moist (CH) -
T.D. 44'

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