EPA/600/2-85/104
                                                 September  1985
        PRACTICAL GUIDE FOR GROUND-WATER SAMPLING
                            "by
M.J. Barcelona,  J.P.  Gib"b,  J.A.  Helfrich,  and E.E. Garske
                Illinois State Water Survey
       Department of  Energy and  Natural Resources
                   Champaign, IL   61820
                   Cooperative Agreement
                             *
                     Project Officer

                      Marion R. Scalf
     Robert S. Kerr Environmental Research Laboratory
                   Ada, Oklahoma  74820
     Robert S. Kerr Environmen|al Research Laboratory
            Office of Researehfand Development
           U.S. Environmental Protection Agency
                  ' Ada, Oklahoma  7-4820
                                               Printed on Recycled Paper

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                            DISCLAIMER
     The information in this document has been funded wholly or in part
by the United States Environmental Protection Agency under assistance
agreement number CR-809966-01 to the Illinois State Water Survey,
through the Board of Trustees of the University of Illinois.  It has  been
subject to the Agency's peer and administrative review, and it has been
approved for publication as an EPA document.

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                                   FOREWORD
     The U.S. Environmental  Protection  Agency was established  to  coordinate
administration of the major  Federal  programs designed to protect the quality
of our environment.

     An important  part   of  the   Agency's  effort  involves  the  search  for
information about  environmental   problems,  management  techniques  and  new
technologies through which optimum use of the Nation's land and water resources
can be assured and  the threat  pollution poses to the  welfare  of the American
people can be minimized.

     EPA's Office of Research  and Development  conducts this search through a
nationwide network of research facilities.

     As one  of  the  facilities,  the  Robert  S.  Kerr  Environmental  Research
Laboratory is the Agency's center of  expertise  for investigation of the soil
and subsurface environment.  Personnel at  the laboratory are  responsible for
management of research  programs  to:   (a)  determine the fate,  transport and
transformation rates of pollutants in the  soil,  the  unsaturated zone and the
saturated zones of the subsurface environment; (b) define the processes to be
used in characterizing the  soil  and subsurface environment as  a receptor of
pollutants; (c) develop techniques for predicting the effect of pollutants on
ground water, soil  and  indigenous organisms; and  (d)  define  and demonstrate
the applicability and limitations  of using  natural  processes,  indigenous to
the soil  and  subsurface  environment,  for  the  protection  of  this  resource.

     This report  contributes  to  that knowledge  which is essential  in order
for EPA  to  establish  and  enforce  pollution  control   standards  which  are
reasonable, cost  effective  and provide  adequate  environmental  protection for
the American public.
                                      Clinton W. Hall
                                      Di rector
                                      Robert S. Kerr Environmental
                                      Research Laboratory
                                     m

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                                CONTENTS
                                                                  Page
FIGURES	    Vll
TABLES	     IX
ACKNOWLEDGEMENTS	     X
EXECUTIVE SUMMARY 	     XI

SECTION 1.  INTRODUCTION	     1
  Literature Overview 	  	     2
  Ground-Water Sampling and Quality Assurance  .  .	     4
  Elements of the Quality Assurance Program 	  .....     7
  Objectives	     8
    Sampling Quality Control  	  	     8
    Analytical Quality Control  .  	  .........     11
  Representative Ground-Water Sampling  	  	     16
    Criteria for Documenting Representative Sampling   ......     19
    Accuracy, Precision, Detection/Quantitation  Limits
      and Completeness	     21

SECTION 2.  ESSENTIAL ELEMENTS OF  A GROUND-WATER SAMPLING PROGRAM     24
  Hydrogeologic Setting and Sampling Frequency  	     25
    Hydrogeologic Setting ....  	  .......     25
    Sampling Frequency  .	     3,3
  Information Needs and Analyte Selection .......  	     37
    Parameter Selection 	  	     39
      General ground-water quality parameters  	  	     40
      Pollution indicator parameters  	  	     41
      Specific chemical constituents. .  .  	     42
    Minimal Analytical Detail for  Ground-Water Monitoring
      Programs	     45
      Detection monitoring data set	     45
      Assessment monitoring data set  .  .  .  .	     46
  Well Placement and Construction  	     47
    Drilling and Well Completion Methods	     48
      Hollow-stem continuous-flight auger 	     49
      Solid-stem continuous-flight auger  	     51
      Cable tool	      51
      Air rotary	     52
      Air rotary with casing hammer	     53
      Reverse circulation rotary  ...  	     54
      Mud rotary	     54
      Bucket auger  	 .....  	     55
      Jetting .............  	     56
      Driving .....................  	     56
    Monitoring Well Design	     56
      Depth of the well	     58
      Diameter of monitoring wells  .....  	     63
      Size of screen	     65
      Grouts and seals	     66
      Multiple-completion wells	  .     67
      Well or sampling point documentation  ...........     67

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                                                                   Page

  Well Development, Hydraulic Performance and Purging Strategy.  .     72
    Well Development	     72
      Techniques for high hydraulic conductivity wells  	     73
      Techniques for low hydraulic conductivity wells 	     76
    Hydraulic Performance of Monitoring Wells 	     77
      Water level measuring techniques	     78
        Steel tapes	     78
        Electric drop lines	     79
        Pressure transducers  	  ....     80
      Hydraulic conductivity testing methods  	     80
        Slug tests	•	     80
        Pumping tests 	     84
        Analysis of water level data	     84
      Well maintenance procedures 	     85
    Well Purging Strategies	     89
      Pumping rates 	     90
      Evaluation of purging requirements  	     90
  Sampling Mechanisms and Materials	     95
    Sampling Mechanisms . :	     96
      Recommendations for selecting sampling mechanisms  	     99
    Sampling Materials	,	    100
      Subsurface conditions and materials affects 	    100
      Recommendations for selecting sampling materials  	    104
  Sample Collection Protocol  . . . .	    105
    Water Level Measurement 	    109
    Purging	    Ill
    Sample Collection .  .	    112
    Filtration  .	    118
    Field Versus Laboratory Determinations  	    120
    Blanks, Standards and Quality Assurance	  .    122
    Sample Storage and Transport  	    124

SECTION 3.  RECOMMENDED SAMPLING PROTOCOLS  	    128
  The Basis for Sampling Protocol Development .  . 	    128
  Sampling Protocol for-Detection Monitoring  	    130
    Analyte .Selection and Sampling Procedures	    132
  Assessment Monitoring 	  ....    135
    Field Sampling Procedures	    146
      Sampling equipment setup, well inspection and  water
        level measurement	    147
      Verification of the well purging requirement	    150
      Sample collection/filtration	•.    151
      Field determinations	    154
      Sample storage and transport  	    154

SECTION l|.  CONCLUSIONS	    156

SECTION 5.  RECOMMENDATIONS	-.    161

SECTION 6.  REFERENCES  	    163
                                   V1

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                                 FIGURES
Number

1 .1

1.2

2.1



2.2


2.3


2.4

2.5


2.6



2.7

2.8

2.9

2.10

2.11

2.12

2.13


2.14


2.15


2.16
Steps in ground-water sampling and sources of error .  .

Steps in water sample analysis and sources of error .  .

Occurrence and movement of ground-water through
a) porous media, b) fractured or creviced media,
c) fractured porous media	 ,	
Local and regional ground-water flow systems in
humid environments	
Temporary reversal of ground-water flow due to
flooding of a river or stream 	
Typical ground-water flow paths in arid environments

Total porosity and drainable porosity for typical
geologic materials	
Type of plume generated from:   a) a slug source or
spill, b) an intermittent source, and c) a continuous
source	

Resulting change in a capture area due to regional flow

Sampling frequency nomograph  	

Well placement and flow paths at low water levels ...

Drilling log sheet  ......... <  •	

Monitoring well construction diagram	
                                                          Page

                                                            10

                                                            14



                                                            27


                                                            28


                                                            29

                                                            30


                                                            32



                                                            35

                                                            36

                                                            38

                                                            62

                                                            68

                                                            71
Schematic diagram of an air-driven well development device  75


                                          .	    83
Hvorslev piezometer test (a) geometry,
(b) method of analysis  	
Effects of waste-handling activity on
ground-water flow paths 	
Percentage of aquifer water versus time for different
transmissivities  	  	
                                                            87
                                                            92
Generalized ground-water sampling protocol  	   110
                                   vn

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Number
                                                                    Page
2.17      A well-head instrumentation package for Eh, pH,
          conductivity and temperature measurements ........   113

2.18      Suggested recording format for well purging and
          sample collection ...................  .   114

2.19      Sample chain of custody form  ..............   127

3.1       Generalized flow diagram of ground-water sampling steps  .   129

3.2       Matrix of sensitive chemical constituents and various
          sampling mechanisms ...................   131

3.3       Recommended sample collection methods for detective
          monitoring programs ...................   136

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                                 TABLES
Number

1.1


2.1


2.2


2.3

2.4


2.5


2.6


2.7


2.8

2.9

2.10

3.1


3.2


3.3


3.4

3.5
Data Requirements for Water-Source Definition  and
Aquifer Representation of Ground-Water  Samples 	
                                                         Page
18
Recommended Drilling Techniques for Various Types
of Geologic Settings 	  .......    50

Well Casing Material Specifications and Depth
  Recommendations  	  *.....    64

Data Needed for a Monitoring Well Construction  Diagram  .    70

Performance Evaluation of Ground-Water Sampling
Mechanisms	   101

Relative Sample Contact Comparison for Selected
Materials	   103

Recommendations for Rigid Materials in Sampling
Applications (In decreasing order of preference)  ....   106

Recommendations for Flexible Materials in Sampling
Applications (In decreasing order of preference)  ....   108

Inorganic Sample Log (Filtered Samples)  	   116

Organic Sample Log (Lab Filtered, If Necessary)  ....   117

Field Standard and Sample Spiking Solutions   	   125

Recommended Analytical Parameters for Detective
Monitoring	   133

Recommended Sample Handling and Preservation  Procedures
for a Detective Monitoring Program 	   139

Metallic Species in RCRA Appendix VIII Which  Require
Only Metal Determinations  	   144

Equipment for Field Sampling 	 .......   148

Sample Purging Parameter Readings  	   152
                                   IX

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                             ACKNOWLEDGEMENTS
     The authors appreciate the advice  and  support  of  the staffs of the



USEPA  R.  S. Kerr  Environmental  Research Laboratory  (Ada, OK)  and the



Environmental  Monitoring  Systems  Laboratory   (Las  Vegas,  NV).    The



comments and suggestions  of  several reviewers were very  helpful in the



preparation of this  document.  The work was also supported  by the  con-



tributions of effort and time  of  Steven Heffelfinger, Michael O'Hearn,



Mark  Sievers,  Pamela  Beavers,  and Pamela Lovett  of  the State Water.



Survey.  The work  has  also been made possible  by:  the Campus Research



Board of the University of Illinois, a large number  of  material and  pump



suppliers,  as well  as the support of our colleagues  and families.

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                            EXECUTIVE SUMMARY




     Ground-water monitoring is a complex   undertaking.   Cost  effective

monitoring relies on careful planning and critical reading of the scien-

tific literature.  These activities will insure that the application of:

well-placement, construction, sampling and analytical procedures, result

in the collection of high  quality  data.   The  information needs  of  each

program must be  recognized and  all  subsequent  monitoring network design

and operation decisions must be made in light of the available data.  In

this  sense, monitoring is an  evolutionary  process  which should  be

refined as the information  base expands.

     Routine monitoring efforts may  be  sustained for  decades.   There-

fore,  it  is unreasonable   to  follow preliminary  guidance  offered for

generalized monitoring activities as the data base for a specific situa-

tion is developed.  Therefore, high quality hydrologic and chemical  data

collected in the detection  phase of monitoring are essential to planning

future activities.   Effective monitoring  efforts 'are  both  dynamic and

flexible.  Our  present  understanding of  natural  and  contaminated  sub-

surface conditions is developing, but incomplete.

     The   practical   elements   of   a   viable   long-term  ground-water

monitoring effort include:

          Evaluation  of hydrogeologic  setting and  program  information
          needs

          Proper well placement and construction

          Evaluation of well-performance and purging strategies; and the

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           Execution  of  effective  sampling  protocols  which
           include  the   appropriate  selection   of   sampling
           mechanisms  and   materials,  as   well  as   sample
           collection and handling procedures.

      Proven ground-water monitoring procedures  are in a state of  rapid

 development at the present  time.    It  is  prudent to specify  monitoring

 methods and results  which  will permit  the  collection of high quality,

 representative information for the most sensitive  chemical  constituents

 of interest.   All  methods used in  a specific situation should be  care-

 fully documented so  that one  can learn  as  the  information  needs and

 dimensions of  the monitoring effort  mature.

      Volatile  organic compounds,  redox   or  pH  sensitive chemical con-

 stituents  are  problematic chemical  constituents which  place significant

 demands  on monitoring efforts.  It  is  clear that,  given properly con-

 structed and maintained  sampling  points,  sampling and handling methods

 which minimize  sample  disturbance  are the  most  cost-effective  means

 available  to provide high  quality  ground-water  information.   Positive

 displacement,  no  gas-contact sampling mechanisms  constructed  of  appro-

 priate inert materials  (Teflon(R)  >  stainless steel > other plastics or

 ferrous  materials) provide the  basis  for an effective monitoring effort.

     Actual  sampling and  analytical performance  (accuracy,  precision,

 detection  and  quantitation limits) which ensure  the collection of  water

 originating  from the  formation of   interest should  be  established  in

 every monitoring effort, regardless of the specific information needs of

 individual programs.  This can  best  be assured  by the implementation of

 quality  assurance and quality  control measures  which are both  checked

and documented  carefully.   The  current   state of  our  understanding  of
                                   xit

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effective monitoring  procedures  requires  that common sense also  play a




large part in planning ground-water sampling efforts.



     If the practical  recommendations  of  this guide are put  into prac-



tice, we  will  have a  much improved information  base  available  in  the



future. This will  be  essential to  making  wise decisions  on ground-water




rehabilitation or  other remedial  actions as well  as  to  improving  our




knowledge of dynamic ground-water systems.
                                   xi i i

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                                SECTION 1
                              INTRODUCTION

     The need  for reliable  ground-water sampling  procedures  has  been

recognized for  years by  a  variety of  professional,  regulatory,  public

and  private    groups.    The technical  basis  for the  use  of  selected

sampling procedures  for  environmental  chemistry studies has been devel-

oped  for  surface  water  applications  over  the  last  four  decades.

However, ground-water  quality monitoring programs have unique needs and

goals  which  are fundamentally  different  from  previous   investigative

activities.  The  reliable  detection and assessment  of subsurface  con-

tamination  situations require  that  minimal disturbance  of geochemical

and  hydrogeologic conditions  occur  during  sampling.   At   this   time

field-proven  well construction,  sampling and  analytical  protocols for

ground-water  sampling have  been developed for many of the  more problem-

atic chemical  constituents  of  interest.    However,  the  acceptance  of

these  procedures and protocols  must  await more careful  documentation and

strong Agency recommendations   for  monitoring   program execution.  The

time and expense of characterizing  actual  subsurface  conditions  places

severe restraints on the methods .which can  be  employed.   Since  the tech-

nical   basis  for documented,  reliable drilling,  sample collection  and

handling procedures  is in the  early  stages  of  development,  conscientious

 efforts to document  method performance under real conditions should be a

 part of any ground-water investigation.

      This guide provides the elements of effective ground-water sampling

 for  routine  applications.    This   is  not  to  minimize  the  ongoing

 development  of  specific sampling or  in situ  sample collection  methods

 for  research  purposes.    It   is   important,  however,  that  essential

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 elements of  reliable sample collection  and  handling are understood  so



 that  the  eventual  development  and  application of  more sophisticated



 methods can be based on high quality data.




      We proceed from the point of  view  that  the placement of wells for



 sampling access has  been done  appropriately  and the task at hand is  to



 construct  the wells  and to  collect water samples representative of the



 formation  of interest.   The sampling procedures described in this guide



 are recommended on the  basis of  long-term  reliability in routine moni-



 toring programs.






 LITERATURE OVERVIEW




      Much of  the literature  on routine ground-water monitoring methodol-



 ogy has  been  published  in the last  ten years.  The bulk of this work has



 emphasized ambient  resource  or contaminant source monitoring rather than



 case-preparation or enforcement efforts.   General references  which  are



 useful  to the design  and execution of sampling efforts are those of  the



 U.S.  Geological  Survey  (1,2),  the  U.S. Environmental  Protection Agency



 (3.^,5,6) and those of a number of  other groups  (7,8,9).  In large part,



 these  past  works treat  sampling in  the  context of  overall  monitoring



 programs providing descriptions of  available sampling mechanisms, sample



 collection and  handling procedures.  The impact of  specific  methodol-



ogies  on the usefulness  or reliability of  the resulting  data have



received relatively little discussion (10,11).



     Routine  monitoring data is  used most  often to  determine if  any



deterioration in water  quality  has  occurred   over time.   In  principle,



this information will accurately  represent hydrogeologic  or  geochemical



conditions at a site and enable  an understanding of  the dynamics of sub-

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surface systems.   A  certain level  of  knowledge   must  be achieved  to



insure the success of a detective monitoring program and to plan modifi-



cations or refinements of the monitoring  program  if  contamination  is




indicated.  Otherwise,  poor decisions may result which will prove to be



far  more  expensive and  time-consuming  than the  careful  performance  of




proper detective monitoring activities would have been.



     High-quality  chemical  data collection is essential in ground-water




monitoring programs.  The technical  difficulties  involved in representa-




tive  sampling  have been recognized  only recently (10,12).   It is clear



that  the long-term  collection of  high quality  ground-water  chemistry




data is more  involved  than merely  selecting a  sampling  mechanism and




agreeing  on .sample handling  procedures.   Efforts  to  detect  and assess



contamination  'Can  be   extremely unrewarding  without  accurate   (e.g.



unbiased)  and  precise (e.g. comparable and complete)  concentration data




on ground-water  chemical constituents.



      Gillham et al.  (13) have  published  a very  useful reference on the



 principal sources  of bias  and  imprecision  in   ground-water  monitoring



 efforts.   Their treatment is extensive and stresses the minimization of



 random error which can  enter  into well-construction,  sample  collection



 and sample handling  operations.   They further stress the  importance of



 collecting precise data over time to maximize the effectiveness of  trend



 analysis, particularly  for  regulatory purposes.    Accuracy is  also very



 important, since  the ultimate  reliability of statistical  comparisons  of



 results  from  different  wells  (e.g.  upgradient  versus  downgradient



 samples) may depend on differences between mean values for selected con-




 stituents from relatively small replicate sample sets.

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 GROUND-WATER SAMPLING AND QUALITY ASSURANCE



      Individual  ground-water  sampling  and  analytical   events   yield



 results which provide a snapshot picture of hydrogeologic   and  chemical



 conditions at a monitoring site.  When the results  of  successive  events



 are  assembled    properly,  they   enable  one  to  better  understand  the



 nature, extent and degree of subsurface contamination.  It  is important



 to remember  that  hydrologic  and chemical  conditions  vary  in both time



 and  space  and  that  the  subsurface  environment  of  ground water  is



 dynamic.    Therefore,  sampling  frequency  and the  location of  discrete



 sampling  points must  be  considered carefully to resolve the  temporal  and



 spatial distributions  of  ground-water  contaminants.




      Each ground-water  sample  must  be  collected so  as  to  insure  the



 reliability of analytical  determinations.   Also,  accurate and precise



 measurements  of water level and hydraulic  conductivity must be  made so



 that  the  analytical results can  be interpreted with consideration of  the



 hydrogeologic system.




      Achieving  the  information  needs of  a ground-water sampling program



 over  a  specified  time  period  requires  careful  planning and execution of



 the sampling  design.   Careful planning is  particularly crucial  to dis-



 tinguishing between the  actual  hydrologic  and  chemical  variability at a



 site  and  that  which  may  arise from  errors  in  the sample collection,



 handling,  and analysis procedures.   Each   field measurement  and  water



 sample  collected  for  laboratory analysis should  also  be  representative



 of  the  discrete sampling point  within the sampling network.   Emphases



 are often placed  on  quality control  and quality  assurance  for  chemical



analysis alone.  One should keep in mind that  there is  no  substitute for



high quality sampling and field measurements.
                                    4

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     A high  quality set of  hydrologic and  chemical  data is  accurate,
precise,  comparable, and complete.   Also, data must  be collected at  a
minimum level of sensitivity and completeness to satisfy the  information
needs of  the sampling program.   Accuracy,  precision,  sensitivity,  and
completeness are measures of sampling  and  analytical performance.  The
accuracy of  each concentration  datum  is  the  measure of its closeness to
the  true  value.   Accuracy  is normally  expressed as  an  average of  a
number of measurements to  the  true  value.   The  accuracy  of analytical
procedures may  be  assessed by  the use of standard reference materials.
In  this  case,  accuracy is expressed  as  the  percentage  of the ratio of
the  measured value to the  true value.  For environmental samples, where
the  true  value is frequently unknown,  accuracy is reported as bias (or
the  percent  recovery  minus  100)  established by  internal  or surrogate
standard  techniques.    Generally,  values  of  bias  in excess  of  ±20%
 indicate  systematic  error or  a  problem with  sampling  or  analytical
 procedures.
      The  precision of a data set is  a measure of  the probability that a
 measurement will  fall within  certain  confidence limits.   Precision  is
 frequently expressed as the standard error (sx)  of the mean  value (x)  of
 a set of replicate determinations (n) at a  stated mean (or  true) value.
 The  standard  error  is related  to  the  standard  deviation (s)  by  the
 expression:   sx = s  *  /n-    Increasing  the number  of  replicates at  an
 established level  of  precision will  generally  improve the level of  con-
 fidence  (reduce random error)   in  the  data.   Duplicate sample values
 which differ  by less than ±50%  relative  difference  indicate good error
 control.

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      Sensitivity is a term which relates  to  both  the  limit  of  detection



 (LOD) and the method detection limit for a particular  chemical  constitu-



 ent.   The method detection limit pertains to  the lowest concentration of



 a particular  chemical  constituent  which  can  be measured reliably in  a



 sample.   The  LOD  is the lowest concentration level which can  be  deter-



 mined to be statistically different from a blank.   A practical  guideline



 is to set  the LOD for a  specific  constituent at a level equivalent to



 three standard deviations  (expressed in mass  or  concentration)  above the



 blank.   This  level  establishes a  threshold  for qualitative or "trace"



 detection sensitivity  and provides  a  degree  of   confidence  in  values



 reported as   "less  than"  a  detectable concentration.   More  stringent



 criteria for  quantitation  set  the limit of quantitation  (LOQ) at 5 or 10



 standard deviations  above  the  blank to insure that quantitation is on a



 sound foundation.   Regardless  of   the  convention  used,  it is  important



 that  the LOD  and LOQ be reported with all  data sets at least for certain



 problematic  chemical constituents.   Completeness   of  the total planned



 data  set  should  include  the  performance  parameters   defined  above.



 Sampling and analysis procedures contribute  to  the overall  quality  of



 the  data set  and  documentation of  control   over  both  systematic  and



 random .error is central to the effort.




     The crucial elements of planning a ground-water sampling effort are



 discussed  in  detail  in   this  guide.    High quality  data  collection



requires  strict adherence to  proven  well  construction, sampling  and



analytical protocols developed with due precautions against bias, impre-



cision,  contamination  or  chemical  alteration  of the  water sample.   In



this respect all field measurements attendant  to water  sample collection

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are considered  part  of the sampling  protocol.   Quality  control  proce-




dures built  into  sampling and analytical  protocols will  guard  against



the loss of data by minimizing both systematic and random error.






ELEMENTS OF THE QUALITY ASSURANCE PROGRAM



     A quality  assurance  (QA)  program is a system  of  documented checks




which validate the reliability of a data set.   QA procedures are used to



verify  that  field  and laboratory  measurement  systems  operate  within



acceptable limits.   These limits should be determined during   sampling




program  design  for each  measurement  which the  program  requires.   The



limits  may  be  modified  or refined  as  new  information  is  gathered.




However,  a documented basis for evaluating  the need for modification



must be established if the expense and manpower involved in ground-water




investigations is to yield cost-effective, high quality data.



     The QA  program should  be  implemented as  a set of basic measurement




procedures and  corresponding  quality control  checks  (6).   The  overall



effectiveness of the quality control checks in reducing errors should be



audited  by a person  or  technique .outside of  the normal  sampling and



analytical  operations.   In this  way the  QA  program will  ensure that



quality  control  (QC)  procedures  are  followed on  a daily  basis  to:



reduce   variability   and  errors,  identify   and   correct  measurement




problems,  and provide  a  documented statistical measure of data quality.



The effectiveness  of  the  overall program demands that all personnel are



aware  of  the  QA/QC  requirements for  the investigation  and that  the




quality  control objectives are understood.

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 OBJECTIVES



 Sampling Quality Control




      An understanding of the specific characteristics of the study site



 is required to plan effective QC checks.  Generally,  this  understanding



 is achieved in phases which  must be recognized by the sampling program



 manager.   Each sampling  datum represents  a single  opportunity to collect



 data from a sampling point which can rarely be retrieved if errors are



 not identified.




      A minimal data  set consisting of selected  field measurements and



 sample volume  recovery must be agreed upon to comprise a "sample."  Then



 a minimum completeness  or  data  recovery  level should  be  defined which



 will   adequately   characterize   existing   conditions   and   fall  within



 expected  limits of future variability.




      It  must  be  kept in mind  that even  with  adequate QA  auditing  of



 sample results within control limits,  there are  system constraints  on



 the subsequent interpretation of sampling  and  analytical  information.



 Hydraulic and  hydrologic properties are, to some extent, scale dependent



 and ground-water  monitoring is  frequently conducted  in geologic forma-



 tions  which are not aquifers.  Further, solution chemical properties are



 only  part of the  subsurface  geochemical  system.   These and other unique



 characteristics of  ground-water  systems may introduce  systematic  error



 or  bias  into monitoring  data sets.  Gillham et  al.  (13) have  addressed



 many of these  potential problems.




     Effective QC  procedures  for ground-water sampling should  be  based



 on  proven field measurement  and  sampling  procedures.   The  wide variety



 of  hydrogeologic and geochemical  conditions  of interest for  contaminant



monitoring have been  investigated by an equally diverse combination of

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procedures.  Very  few  of these procedures have been  standardized  after



systematic  development  and  controlled  evaluation  trials.    Therefore,



tailoring  QC  procedures  to  the situation  at hand  is  a complex  task.



Well construction and development techniques  as well  as  sampling proce-




dures,  mechanisms,  and  materials  all have  the  potential to  introduce



errors  into monitoring  results.  These  sources of error  should  be con-




sidered in the development of QC checks.



     Given  that  the ground water may be under relatively high  partial




pressures  of   nitrogen   or  carbon   dioxide,  water  samples   need  to  be



handled very  carefully.  The  samples also originate in  geologic  media



which are  rarely isotropic at  the regional  to local scale.   Frequently,



suspended  solids accompany water sample  collection which can seriously



affect  analytical  results.   The   discussions provided  by Sisk  (6)  and




Brown and  Black  (14) are useful in planning general QC  procedures  for




ground-water sampling efforts.



     A  common  challenge  to effective  ground-water data  quality  control



is  that the accuracy of a sample result is difficult to judge, since the



true  value is. unknown.   Accuracy of individual measurements  must  there-



fore  be judged by  the analysis  of a reference material or by spiking the



sample  with a known quantity  of  analyte followed  by  reanalysis.  The



results from  field  blanks  and standards  may then  be  compared  to  the



results of laboratory standards and spiked samples to gain confidence in



the accuracy  of sample  analyses.  The precision of measurements within a



data  set  is   thus  defined  as  the average  agreement  between repeated



measurements  on  samples  and standards.   Quality  control over the first



four  steps  involved in sample access  and  retrieval  is difficult  to



achieve.   This is   shown schematically  in Figure 1.1.  Therefore, it is

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            Step
       Sources of Error
  In-Situ Condition
 Establishing a Sampling Point
 Field Measurements
Sample  Collection
Sample Delivery/Transfer
Field Blanks, Standards
Field Determinations
Preservation/Storage
Transportation
 Improper  well  construction/
 placement;  inappropriate
 materials selection

 Instrument  malfunction;
 operator  error

 Sampling  mechanism bias;
 operator  error

 Sampling  mechanism bias;
 sample exposure, degassing,
 oxygenation; field conditions

 Operator  error;         '
 matrix interferences

 Instrument malfunction;
 operator  error;
 field conditions

Matrix interferences;
handling/labeling errors

Delay; sample loss
Figure  1.1.  Steps  in ground-water sampling and sources of error
                                10

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very important to choose well  construction  and  sampling  protocols  which




are simple and minimize disturbance in order to  collect accurate data.



     One  can  readily observe  that  the integrity  of  both the  sampling




point and  sampling  mechanism are as  critical  as operator expertise  to




minimize the error or  variance  introduced  into  the  sample  results.




Decisions  made in  establishing  a  sampling  point  and   the  choice  of



sampling  mechanisms  can introduce  significant  systematic error  (bias)



into all subsequent sample results which may go  undetected without  care-



ful QA  auditing  of  the data as soon as possible.   Further,  documented




sampling QC checks and QA audits  are  controlling factors in  the useful-



ness  of the  analytical  data.  The  laboratory  can  only  be expected  to



reliably report data  based  on the samples, field  standards,  and blanks




as received.



     The potential sources of error noted in Figure 1.1 define essential



elements of sampling quality control.   These are:



     1)  Proper  calibration  of  all  sampling   >and  field  measurement




            equipment



     2)  Assurance of representative sampling,  particularly with respect



            to  site  selection,  sampling  frequency,   well  purging  and



            sample collection



     3)  Use of proper sample handling precautions





Analytical Quality Control



     Laboratory quality control  is  necessary to ensure valid analytical



results.   Analytical QC procedures must  be developed in  parallel with



those  involved in  the sampling  operation.   Whether  the   laboratory



analyses  are  made by an  in-house or' contract  lab,  the  value  of  blind
                                   11

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 control  samples and  blanks  submitted as "normal"  samples  is enormous.



 Blind  control samples may be prepared solutions  or ground water spiked



 with  the  contaminants  of  interest  at  known  concentrations.    Blind



 controls  provide  the only  true check  on the  accuracy  of  analytical



 results.  Effective QC procedures provide daily checks that the analyti-



 cal    system is  in  statistical  control.    Blind  control  samples  and



 multiple  determinations  should  be emphasized  wherever possible.   Repeat



 sampling  and analysis is a  poor  second  choice to  performing the tasks



 adequately in the  first  place.   The variables involved in sampling must



 be controlled to  the  maximum extent possible for  the rigors  of  labora-



 tory  QC  procedures  to  be meaningful.   Three  useful    references  for



 planning  QA  and QC  for  ground-water  data  collection are  contained in



 reviews by Nacht (15) and Keith et al. (16), and Kirchmer (17,18).



     The  need to  establish  a measure of  confidence in  the  analytical



 results is underscored in  a  formal  laboratory QA  program.   The  program



 should  address  three main functions:    the control, determination  and



 documentation of data quality.  These are minimal criteria for effective



 laboratory QC, which  should  extend  to  field determinations.   Regardless



 of the  analytes of interest  and  the degree of  sensitivity required by



 the information needs of the  ground-water  sampling program, every labo-



 ratory should adhere  to well-documented  control  procedures.   These pro-



 cedures have been reviewed in  general  by  Dressman  (19)  and Dux  (20).



The  expectations  which  may  be  anticipated  from contract  laboratory



 services  are no  less rigorous  than  those  of  in-house  laboratories.



Specifics of such cooperative sampling/analytical arrangements have been



 covered by Kingsley et al.  (21)  and Kingsley (22).
                                   12

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     In  contrast  to  the  steps  in  the  sampling protocol,  analytical



quality control is straightforward, provided that the analytical labora-



tory staff is made aware  of  any unusual attributes of the samples. This



.type of feedback can substantially improve the validity and interpretive




value of measurement results.



     The steps of  an analytical protocol  are normally quite specific to




the  individual analytes  of interest.   The  planning, of comprehensive QA



procedures should  be done  carefully  with  each  individual step  in the



analytical  protocol  taken  into account.    In  general,   the  analytical



protocol can  be  depicted as shown below  in Figure 1.2.   Appropriate QA



audits  of  the QC measures at each step should serve  to  keep potential




analytical errors in control.



     Instrument malfunctions, analyst errors, and the use of "aged", old



or  deteriorated  standards pose  problems  that can be  detected  and cor-



rected  with good QA/QC  procedures.  More difficult obstacles arise from



the  application  of "standard" methods to the analysis of highly contami-



nated samples.  Matrix or direct  interferences are among the most diffi-



cult sources  of  error to bring  under  control  (23).   Thoroughgoing QC



requires  that  standard  methods  be  validated  for  the  most difficult



sample  matrix encountered within a particular set  of samples.   Valida-



tion by  internal  standardization techniques should  be  done  over the




entire  range  of  concentration represented in the  sample results (24,25).



     The necessary elements  of  an effective  laboratory QA program are:



     1)  Adherence  to documented laboratory QC  procedures,  including:



            proper calibration  of instrumentation, verification of  daily



            standardization   and   analytical   performance   parameters



             (accuracy and precision)  for all procedures,  daily analysis
                                    13

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           Stec
 Samples,  from Storage
 Field Blanks and Standards
       Sources of Error

"Aged" samples; loss of
analytes; contamination
 Subsampling
 Procedural Standards
 Analytical Separation
 Analysis
 Reference Standards
Sample aging/contamination
in lab; cross-contamination;
mishandling/labeling

"Aged" standards;
analyst error

Matrix interferences;
inappropriate/invalid
methodology; instrumental
malfunction/analyst error

Matrix interference;
inappropriate/invalid
methodology; instrumental
malfunction/analyst error

"Aged" standards
 Calculations
 Results
Transcription/machine errors;
sample loss in tracking system;
improper extrapolation/inter-
polation; over-reporting/
under-reporting errors
Figure 1.2. . Steps in water sample analysis and sources of error
                               14

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            of sample replicates,  standards,  spiked samples  and  blanks



            by approved methodologies and the use of QC  charts  to docu-




            ment the validity of laboratory results




     2)  Participation in round-robin or interlaboratory studies



     3)  Prompt recording,  storage  and retrieval of laboratory results



            with the corresponding analytical  performance parameters




     The development of a total  QA/QC  program for ground-water  sampling



and analysis must be  approached  carefully.   The care exercised in well



placement and construction,  and sample collection and analysis,  however,




can pay real  dividends  in the control  of  systematic errors.   Repeated



sampling  and field  measurements  will minimize  the' effect  of  random



errors induced by field conditions or system malfunction.



     The  responsibility  for  the  selection  of reliable  sampling  and




analytical  methods  is  to ,some  extent  shared  by  the  sampling program



director and the client or  agency  in need  of  the  information.  As more



high quality  data become  available,  QA/QC  planning will be  facilitated



for environmental   sampling programs.   The  American   Chemical Society



Committee on  Environmental  Improvement  has published a  valuable  refer-



ence for  reporting data  quality  (e.g. accuracy,  precision, LOD,  LOQ,



sensitivity)  in a consistent format for monitoring  purposes  (26).  This



guide  contains  recommendations   based on  experience   and    published



results.  It will be revised and modified accordingly as the  information



base grows.  Therefore,  it should be used  in conjunction with the  future



amendments of existing standard procedural  documents (27,28,29).
                                   15

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REPRESENTATIVE GROUND-WATER SAMPLING



     Representative  sampling  is probably  most  difficult in  situations



where reliable data  is  needed most  (30).   Chemists have struggled  for



decades with the  difficulties  involved  in  obtaining representative  ana-



lytical results  from bulk solid or  natural  water samples.    Scientists



who have worked with environmental samples  fully appreciate  these diffi-



culties.  Statisticians, on  the other hand,  hold exact views  concerning



the characteristics  of  representative samples.   Statistically,  a repre-



sentative sample  is  a subset  of a set  (or universe called the  popula-



tion)  which  has  the  average  characteristics    of   the  set.    For



ground-water samples, one must  assume that such a sample is representa-



tive  of  the  aquifer  or  geologic  formation  from  which  it  came.  It



follows then that  the results  of representative sampling and  controlled



analytical  determinations  provide an  accurate measure  of  the  in  situ



condition at the time of sampling.   Claassen (31) has demonstrated  that



an  approximation  of the  representativeness  c>f  a ground-water  sample



alone is achievable given the complexities  and costs involved  in exhaus-



tive  investigations  of  the subsurface.  Verification  of the  extent  of



representativeness is thus the responsibility of project staff.



     The goal of representative sampling is a relatively straightforward



undertaking in materials' analysis or investigations of well-mixed homo-



genous surface-water  bodies.   Sources of  error or  variance in sampling



or  analysis  should  be  independently   verifiable  if  the measurement



systems are in  statistical control.   This is  possible  if  truly random



sampling can be  conducted  and  invalid samples  can be identified through



the use of controls and blanks.
                                    16

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     Representative ground-water sampling,  however,  is  limited  to repli-



cate discrete samples from  established  sampling points which may  accu-




rately  and  precisely reflect  the  average properties  of  the  measured



system.  Sampling accuracy,  however, cannot be unequivocally  verified in



the field.   It  is vitally  important  that  the limits of the  measured



system  are  understood  by  the  project   personnel  responsible  for  the



interpretation of  the data  (12).   In  this way, the  interpretation of



"high" or "background" levels of specific  chemical  constituents will be



consistent with  the  hydrogeologic  system  description.    Statistical



theory and manipulations applied to data on hydrogeologic or  geochemical




systems cannot substitute for expert judgment.



     Claassen (31) pointed  out  that there  exists a  marked scale depend-




ency  of  the heterogeneity  of aquifer systems.   He  suggested  that most



aquifers are microscopically (-100 urn) heterogenous, some are homogenous



on  a  somewhat larger scale,  while all   are probably heterogenous  on a



regional  scale  (km).   His  publication  details  suggested guidelines for



evaluating  aquifer representation  which should  be carefully   considered



in  planning ground-water investigations of  all types.  Data requirements



for water  source definition and aquifer representation of ground-water



samples  are listed in Table 1.1.   This  data should be recorded for each



sampling  point  and updated after  each  scheduled well  maintenance  (e.g.



redevelopment  operation).   The  well  pumping  history,  in  particular,



should be updated  on  each sampling date to insure that any deterioration




in  well  performance can be  fully documented.



      Hydrologists  and geochemists  have made progress towards the resolu-



tion  of  these problems of scale for aquifer representation.  The work of




Ingamells  (32)  and Ingamells and Switzer (33) is notable in this area of
                                    17

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  Table 1.1.  Data Requirements for Water-Source Definition and
          Aquifer Representation of Ground-Water Samples
              (Modified after Claassen, reference 31)
A.  Drilling  history

    1.  Well  depth and diameter
    2.  Drill-bit type and circulating fluid
    3.  Lithologic data from cores or cuttings
    1i.  Well-development before casing
    5.  Geophysical logs obtained

B.  Well-completion data

    1.  Casing sizes, depths and leveling information relative to
          both land surface and top of casing
    2.  Casing material(s)
    3.  Cemented or grouted intervals and materials used
    1.  Plugs, stabilizers, and so forth, left in hole and
          materials used
    5.  Gravel packing:  volume, sizes, and type of material
    .6.  Screened, perforated, or milled casing or other intervals
          which allow water to enter the borehole
    7.  Pump type, setting, intake location, construction
          materials,  and pump-column type and diameter
    8.  Well maintenance record detailing type of treatment and
          efficiency

C.  Well pumping history
    1.  Rate
    2.  Frequency
    3.  Static and pumping water levels

D.  Estimation of effect of contaminants introduced into aquifer
    during well drilling and completion on native water quality

E.  Effect of sampling mechanism and materials on the composi-
    tion of ground-water sample

    1.  Addition of contaminants
    2.  Removal of constituents
        a.  Sorption
        b.  Precipitation
        c.  Degassing
                                18

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research, however  its practical  application  to hydrogeologic  problems



has been limited.  An inventive technique for  resolving scale and heter-




ogeneity problems  in aquifer representation has been reported  by Keely




(34).  Briefly, a combination of pumped wells  or pumping wells and moni-



toring  wells  are  sampled  over a time  series  simultaneous with  water



level and yield measurements.  The combined chemical time series samples




and the  drawdowh results provide  a  data set which  describes the spatial



variability  of  dissolved  chemical  constituents,   as  well  as  aquifer



transmissivity and storage   values.   The application of  this technique



to a contamination problem in Washington State yielded encouragement for



its use  and refinement for future work (35).  Multi-level sampling point




arrays also hold promise for the resolution of scale problems.  However,



most   of the  published  reports are limited  to  demonstrations  of tech-



niques  (36,37,38).   Systematic evaluations   of  the  performance of sam-




pling protocols for  chemical constituents are rare.





Criteria for Documenting Representative Sampling



     It  should be evident  that representative  sampling in  the strict



statistical  sense  is  a   challenging  undertaking.   To  some extent the



criteria for "representativeness" depend on the level of detail required



in the  program.  The requirements for documenting representative samples



from the measured  system will  vary  from site to site  and  perhaps from



sampling point  to  sampling point,  depending  on  the  situation under



investigation.   This  document  defines  representative  sampling a priori



as representative  for  the specific purposes of the ground-water  investi-



gation.  In the  case of regulatory compliance studies, the criterion for
                                    19

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representativeness may  be that which will  be considered by  the  appro-



priate  agency to  be representative  of  the  regulated  facility.    For



example,  charge  balance considerations  and minimum  acceptable accuracy



and  precision limits   for  the  determination  of  the  contaminants  of



interest are useful criteria for representative samples.



     There are two sets  of   essential  requirements for  representative



sampling. The first  set of criteria must be  based on  some  knowledge of



the measured system and the experience of project planning staff.   Close



attention must be  paid  to the  requirements  listed  in Table  1.1,  as well



as the  potential impacts of:   well placement, sampling  frequency,  the



mobility and persistence of chemical constituents and natural sources of



variability in the hydrogeology and geochemical characteristics of  the



site.  These criteria are subjective to  some  extent  and  evaluation of a



data set's  "representativeness" may  only  be  possible after  extensive



preliminary investigation.  As  the  level  of detail involved in a sampl-



ing program increases,  one must be  careful  to  avoid  excesses in  borings



for  core  collection  or   well  installation.   Every  disturbance of  the



subsurface has the potential to contribute  to  contaminate migration  and



confound  data  interpretation.   Good detective work  on site  character-



istics and operational history  can  minimize the  cost and  disturbance of



extensive sampling activities.



     The second  set  of  criteria addresses  the details of  the sampling



and  analytical  protocols.   They are  based on  the  assumption  that  a



properly  designed  and  executed ground-water  sampling  plan will enable



documented evaluation of the  significance  of the sample mean and  the



variation between  the  mean and other  members  of  the  set.    Basically,
                                   20

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reliable protocols provide a known level of  confidence  in  the  represen-




tativeness of the sample.




Accuracy, Precision,  Detection/Quantitation Limits and Completeness




     The critical performance parameters common to both the sampling and



analytical protocols  are accuracy,  precision, minimum  detection  limits



and completeness.  Proper planning of  a comprehensive sampling program,



which  includes  QC  check  and QA  auditing  procedures  to insure  high



quality results,  requires  that  each step in  the  protocols is  evaluated



for each of the  performance parameters.   The  most direct way to meet



this requirement  is  to specify  and  document the sampling protocol  for



the  most  sampling  error  prone  class  of  chemical  constituents  of



interest.  In each class, certain constituents may require refinement of



the protocol for reliable sampling.  Detailed documentation of  accuracy,



precision and minimum  detection  limits for  the  corresponding analytical



procedures should be  provided as well.  In this  manner sampling  errors



can  be evaluated  independently  from those  involved  in the  analytical




work.



     Establishing  the  performance of  the  sampling protocol to achieve



error  control  requires the  execution  of a  controlled  sampling experi-



ment.    If  possible,  one  should seek  to  verify sampling accuracy and



precision over  the potential concentration range of  the most  sensitive



chemical  constituent of  interest.   This type of experiment could estab-



lish the lowest practical  level of a  chemical  constituent which  can be



sampled  within certain  accuracy  and precision   limits.   This minimum



"collectable"  concentration  would correspond to  the  LOQ for analytical



operations.  However, sampling accuracy cannot be verified in the field,
                                    21

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since  the "true" or  in  situ value is  unknown  and it is  most, unlikely



that any single  (or average) value for a particular chemical constituent



could be considered as the "true" even for very localized sites..,  There-



fore, the  accuracy  of the sample retrieval and  collection steps,  which



involve both the sampling mechanism and materials,  must  be evaluated in



controlled  laboratory experiments.    These  experiments  should  simulate



field conditions and  maintain  a known  concentration source of  the  most



sensitive  chemical  constituent  of  interest.   Precision,  on  the  other



hand, can  be  evaluated in  the  field  or the laboratory  if a  sufficient



number of replicate determinations can be performed.



     There  have  been  few  controlled sampling  experiments reported  which



provide supporting  data  for the  evaluation of  representative  sampling



performance.    Field    experiments  have  been   limited  to  documenting



apparent  discrepancies in  accuracy  by different  sampling  techniques



(11t39), or studies which establish the precision of developing sampling



techniques  (40).   Since it  is  extremely difficult to maintain  control



over sampling  performance which may be  largely  operator dependent,  the



choice of a specific  sampling mechanism must be  made  very  carefully.  If



a  sampling mechanism  is  chosen which  has  not  been  subjected to  con-



trolled performance testing, the user  should provide documentation  which



assures control  over  mechanism related  error.   It may  be  that  evalua-



tions of the accuracy of sampling mechanisms must  be inferred by  com-



parisons with published data and the  precision should be  established for



each study with  a well designed sampling experiment.  Thorough  consid-



eration  must   be given  to  sources   of systematic  (bias)  and random
                                   22

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(imprecision) error at each step in the sampling protocol.   The  sampling



mechanism  is  of  particular importance  in this  regard as  it  largely



determines the complexity of the sampling protocol.
                                   23

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                                SECTION, 2                . ,       .«,
          ESSENTIAL ELEMENTS OF A GROUND-WATER SAMPLING PROGRAM

     The technical literature  on  ground-water  sampling provides  a great

deal  of  information  on  selected  aspects  of  an  efficient  sampling

program.   However, valid  data on  reliable  methods-for  drilling,  well

completion/development,  and  sampling, reactive or  organic chemical, con-

stituents in ground water are scarce.

     Recommendations  for   conducting .  ground-water   sampling  programs

stress  the  use  of   "appropriate'1   drilling -  and  sampling  methods  or

material's  choices  which will  permit  the collection  of representative

samples.   This leaves many  critical decisions open to  discretion  when

data on the hydrogeologic setting or dissolved chemical constituents may

be   incomplete.   This  section provides  specific recommendations  for

establishing a sampling point and  conducting a sampling effort  which

should be sufficient  to  the  needs  of most routine  ground-water investi-

gations.  In many cases,   the  detail and precautions  which must be  con-

sidered in planning a representative sampling effort cannot be predicted

until a  substantial   amount  of high, quality  data  is made available  by

preliminary sampling.

     Due care  to insure the collection of unbiased,  precise  hydrologic

and chemical data should be  exercised from the outset  in all  monitoring

efforts.  The data set should then be subjected to  constant  scrutiny and

reevaluation as the situation  becomes better defined.   This approach is

logical  and cost-effective.  Poorly conceived or  "cook-book" .sampling

programs will  ultimately end  up  generating  poor  data at  considerable
                                   24

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long-term expense.  The logical,  phased-'approach also facilitates  regu-



latory review of the data and decision-making for assessment or remedial




actions.






HYDROGEOLOGIC SETTING AND SAMPLING FREQUENCY        <



     The hydrogeologic  conditions  at  each site to be monitored must  be



evaluated for the potential impacts the setting may have on the develop-



ment of  the monitoring program  and the  quality  of  the resulting data



(41).  The  types  and  distribution  of  geologic materials,  the occurrence



and  movement  of ground water  through those materials,  the  location  of



the  site  in the regional ground-water flow  system,  the relative perme-



ability  of  the  materials,  as well  as  potential interactions  between



contaminants  and  the  geochemical  and biological  constituents of  the




formation(s) of interest must all be'considered.  •





Hydrogeologic Setting



     There   are  three  basic types   of   geologic  materials  normally



encountered in  ground-water monitoring programs.   These are:  1) porous



media;  2)   fractured  media;  and  3) fractured porous 'media.   In porous



media,  the  water and contaminants move through the  pore spaces between



individual  grains of  the media.    These media include sand and gravels,



silt,  loess,  clay,  till,  and sandstone.  In fractured  media,  the water



and  contaminants move  through cracks  or  solution crevices in otherwise



relatively  impermeable  rock.    These media  include  dolomites.,  some



shales,  granites,  and crystalline rocks.  In fractured  porous media, the



water  and contaminants move through  both the intergranular pore spaces



as  well as  cracks or  crevices in  the rock  or soil.   The occurrence and



movement of  water  through the  pores and  cracks or solution  crevices
                                    25

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 depends on the relative porosity and degree  of  channeling from  cracks or



 crevices.   These media include fractured tills,  fractured sandstone, and



 some fractured shales.  Figure 2.1 illustrates the occurrence  and move-



 ment  of  water   and   contaminants  in  these  three  types   of  geologic



 materials.




      The distribution of these  three  basic  types of geologic  materials



 is  seldom  homogeneous or uniform.  In most  settings,  two  or more types



 of  materials  will be present.  Even for one type of material at a given



 site,   large   differences    in   hydrologic   characteristics  may   be



 encountered.   The heterogeneity of the materials can play a significant



 role in the rates of both tracer  and  contaminant transport,  as well as



 the  optimum strategy  for monitoring a site.



     Once  the  geologic setting is  understood, the site hydrology must be



 evaluated.  The location of   the site within the regional ground-water



 flow system also  must be determined.   Piezometric surface  data or water



 level  information of each geologic 'formation at  properly selected ver-



 tical and  horizontal  locations.is needed'to determine the horizontal and



 vertical ground-water, flow  paths at the site of  interest.   Figures 2.2



 and  2.3 illustrate two  geohydrologic  settings.commonly ericountered in



 eastern regions of the United States where ground-water recharge', exceeds



 evapotranspirational  rates,   Figure  2.4 illustrates, a .common geohydro-



 logic setting for the arid western regions of the United Stated.



     In addition  to determining  the  directions  of ground-water  flow, it



 is essential to determine the approximate rates  of ground-water  movement



to  properly design a  monitoring program.    Hydraulic conductivity  and



gradient data  are required to estimate the Darcian or bulk  flow  rates of



ground water.    Hydraulic conductivity data  should  be determined  using
                                   26

-------
(a)
Figure 2.1.  Occurrence and movement of ground water through
      a) porous media, b) fractured pr creviced media,
                  c)  fractured porous media
                            27

-------
 LOCAL AND REGIONAL GROUND WATER
FLOW SYSTEMS IN HUMID ENVIRONMENTS
                           Figure 2.2
                                28

-------
   TEMPORARY REVERSAL OF GROUND-WATER FLOW DUE TO
             FLOODING OF A RIVER OR STREAM
Temporary
reversal of
groundwater flow
                       Figure 2.3
                             29

-------
        TOTAL POROSITY AND DRAINABLE  POROSITY FOR TYPICAL
               GEOLOGICMATERIALS  (After Todd, 1980)
50

45

40

35

30

25

20

15

10

 5

 0
               T	T
T	1	T
                                 I     I
                                                            T	T
                                                 Porosity
V
U
                                Specific yield
                               (drainable porosity)
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                                                  i,
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                                               O
                                               CO
         1/16  1/18  1/4   1/21    2    4    8   16    32   64  128  256

                         Maximum 10% grain size, millimeters
          (The grain size in which, the cumulative total, beginning with the coarsest material
          reaches 10% of the total sample.)
                                Figure 2.5
                                     32

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artefacts  into  the results.   Physical  and  hydrologic conditions  will
determine  whether  or not  evidence for  chemical  or  biological  inter-
actions  can  be  collected.   If  the   potential  for  these reactions  or
transformations  exist,  consideration  should be  given to screening for
likely intermediates or transformation products.
     The  importance  of  understanding the  hydrogeologic setting  of the
site to be monitored cannot be overemphasized in developing an effective
sampling  program.   Similarly,  the effects of the  hydrogeologic setting
on  the  samples  to  ,be  collected  should be  evaluated  in   detail and
considered in developing the sampling protocol.
Sampling Frequency
     Traditional determinations  of optimum frequencies for ground-water
sampling have been made by regulation  or from statistical arguments in
analogy with surface  water   monitoring experiences  (43,W.  Sampling
 frequencies  determined by  these methods  emphasize  data needs  and  the
 economics of sample collection  and analysis.   A more reasoned approach
 is to  first evaluate  the type  of  source  that is  being  monitored, a
 spill, slug, intermittent, or continuous  source.   Then one  should con-
 sider the likely  pulse or continuous plumes of  contaminants  to be  moni-
 tored;  determine the  minimum  desired  sampling frequency  in terms  of
 length along the  ground-water flow path and use hydrologic  data  to cal-
 culate the required frequency to satisfy these goals.
      The  type  of potential pollution  source  has  a  direct  influence on
 the resulting plume that may be created.  In the case of a spill  or slug
 source  of pollution,  discrete plumes may result.   The  size, shape,  and
 rate  of plume movements  will be  dependent  on:   source characteristics,
                                     33

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 the  hydrologic and  geologic nature  of the  site in  question and  the



 chemical reactivity  and biological interaction  of  individual  contami-



 nants with  the subsurface  environment.   Figure  2.6a illustrates  this



 type of phenomena.   Intermittent releases  of a pollutant may result  in a



 series of discrete plumes that  may or may not overlap depending on  the



 relative frequency  of the  releases and  the factors  mentioned above.



 Figure 2.6b  illustrates this type of phenomena.




      Continuous sources of pollution result in the development  of plumes



 that may approach steady  state  conditions for nonreactive conservative



 chemical species.  The size  and  shape  of this  type of plume can be esti-^



 mated using a  relationship  described  by Todd  (42).   Todd analyzed the



 effects  of regional ground-water  flow on the circular cone of depression



 in  the water surface  developed  by pumping  a well.  For the purposes of



 evaluating  the  effects of  a  pollution source  on  the  regional  flow



 system,  the  pollution source  can be treated  as  an  injection  well.  The



 expression describing the  boundary of the  affected  downgradient  region



 (ignoring dispersivity) is as follows:




                        -(y/x)  =  tan (2KbI/Q)y              (Eq.  2.1)



 where K  -  hydraulic conductivity, in liters per day per square meter



       b  =  aquifer thickness, in meters




       I  -  hydraulic gradient,  in meters per meter



       Q  -  leakage rate from the source,  in liters  per minute



     The rectangular  coordinates  (x and y)  are  as shown  in Figure  2.7



with the origin at the center of  the source.




     Based on the expected type  of plume,   a  decision  can  be made con-



cerning how  often  in  the  flow path samples  are required for  adequate



definition of plume  dynamics.  This decision can then  be translated into
                                   34

-------
TYPE OF PLUME GENERATED FROM (a) A SLUG SOURCE OR SPILL,
 (b) AN INTERMITTENT SOURCE, AND (c) A CONTINUOUS SOURCE
                       A
 (a)
(b)
                                                 (0
                      Figure 2.6
                             35

-------
RESULTING CHANGE OF A CAPTURE AREA DUE TO
           REGIONAL FLOW (After ref. 42)
           O   Ground surface
            tm
            w<
             Original piezometric surface-
              , Slope = /
                             Drawdown curve

                          Impermeable
7— It
1
Confined aquifer
< ^
h
b
f
                         Impermeable
                 Figure 2.7
                       36

-------
a sampling frequency using the hydrogeologic  parameters measured at  the



site.   The  velocity  of  ground-water  flow is  described  using Darcy's



equation and the effective porosity of the materials being monitored:



                             v  =  KI/7.48N                   (Eq.  2.2)




where v  =  velocity of ground-water flow, in meters per day



      K  =  hydraulic conductivity, in liters per day per square meter




      I  =  hydraulic gradient, in meters per meter




      N  =  effective porosity, in percent



     Figure  2.8  presents  a nomograph for translating the  hydraulic data




into sampling  frequencies at.various flow path lengths.






INFORMATION NEEDS AND ANALYTE SELECTION



     The  information needs of a  ground-water sampling program determine




both the  scope and details  of field and laboratory efforts.  The needed



chemical  information,  in particular, will drive  the selection  of  tech-



niques,  procedures  and'  methodologies   which  will  constitute  integral



sampling  and analytical protocols.   All of the steps in these protocols



must be tailored  to  the analytes of interest  by a well conceived plan



 for field and laboratory operations.   Detailed data on source composi-



 tion and the  type or  extent  of  contamination available to most initial



 investigations is  usually limited.   This is  particularly  true of ground-



 water  investigations at waste management facilities.  Regardless of  the



 state of  the information  base,  the  planning  effort  must  incorporate




 flexibility to meet  a variety of contingencies.



      It is  often  more  cost-effective and reasonable to plan the  effort



 for the maximum long-term return on the investment of fiscal and human
                                    37

-------
SAMPLING FREQUENCY NOMOGRAPH
(K)

10°

'

ID'2-


-4-


10-6-
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io-«-
•1
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8 - D \
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QUENCY OF SAN
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. 103
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1
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£











*•*,





(D)
100 —
80
60
40

20

10 _
8
6
4

2

1.0 —
.8
.6
.4
"^ .1 —

(N)
ta
£ ,os -i
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"- .15-
(9
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— '"^ .50"'




: POROSITY
S
Ul
UL
Ul


F = DN
	 — = 13.8 days
864 Ki
Example (clean sand)
K ." 10"1
i - ID"4
N • 0.30
D = 0.4 meters
      Figure 2.8
           38

-------
resources.  Therefore, the planning   effort  should  anticipate  difficul-


ties and  allow  for  refinement of the sampling and  analytical  protocols


as new data becomes available.


     The basis of a successful monitoring  program is  a robust,  integral


sampling protocol, coupled to proven'analytical schemes.  Both field and


laboratory  personnel  should  be  involved  in planning,  once  the  minimum


information needs  of the   program are  identified.   In  this way,  the


potential impact of seemingly minor details of the program protocols can


be judged more appropriately.             .



Parameter Selection                        ,


     Parameter  selection  for  chemical measurements  is very important to


the  effective  planning   of   sampling  and  analytical  protocols.    For


exploratory efforts,  it  is useful to obtain slightly more chemical and
                                              *             •          •.

hydrologic  data than  that required by the  immediate information needs of


the  program. . The added data  can normally  be put to good use as the site


conditions  become  better  defined.   For  example,  in   a situation where


essentially no  chemical  .data  for a  site  exists,  a  complete  mineral


analysis  should be included.   The results  provide an internal consis-


tency  check  on major  ionic  constituents,  field  determinations   (e.g.


alkalinity) and the potential effects  of unusually  high levels of metals


or  nutrient anions (16,23).   Reliable analytical methods for ionic con-


stituents and routine field  determinations  (pH, Eh,  temperature,  con-


 ductance  and  alkalinity)  are  well  referenced for ground-water samples by


 the USEPA (27,28,29)  and various  other  groups  (45,46).  The results of


 the complete mineral analysis and field determinations define the major


 ion solution chemistry which is  quite valuable to obtaining an overall
                                    39

-------
 picture of the  subsurface  system of interest.   The  major  ion chemistry


 determines the inorganic background and potential for matrix  effects  in

 sampling and  analysis.   Chemical speciation of  many specific inorganic

 constituents of interest (e.g.  Fe,  Cu,  Pb)  may  be controlled by  the


 inorganic solution chemistry.   In turn,  the speciation of  the  chemical


 constituents  of  interest  effects  subsurface  transport   behavior   and

 sensitivity to  either  handling  disturbances  or recovery in  analytical

 separations.


      With a complete mineral  analyses  and a'  clear  view of information

 needs,  one  can   then  select  the  additional  chemical parameters   of

 interest.   These parameters may be characterized as general  ground-water

 quality parameters,  pollutant  indicator parameters and specific  chemical
                                              i
 contaminants.


 General Ground-Water Quality Parameters


      Parameters  which  give a  general  overview  of  ground-water quality

 relate  to  total  dissolved solids content  (e.g. Na+,  Cl~, S0ij=) and tra-

 ditional  water treatment difficulties of  ground water.   Taste  or  odor

 removal needs  associated with  the presence of  dissolved iron,  manganese

 and total phenols  vary substantially among ground-water supplies. Beyond

 The determination  of ground-water  quality parameters may also provide an

 indication  of  severely contaminated conditions.   The choice  of sample

 collection  and handling methods  should be  given careful consideration.

Degassing  (e.g.  loss of  C02)  and oxygenation  (e.g.  loss of  Fe,  trace

metals) can markedly effect analytical  results,  even for water  quality

constituents at  the ppm  (mg-L~1) level (11).   The  sensitivity of  the

results for these  water  quality parameters to sampling  procedures is  a
                                   40

-------
function of the major ion chemistry and chemical speciation.   Therefore,



complete mineral analyses should be included in most  sampling programs,




if only on a limited basis.                 •




Pollution Indicator Parameters         ...



     Contaminant monitoring program requirements for parameter selection




reflect the following objectives:  to detect whether or not the operation



of a facility results in the contamination of ground water, to determine




whether  concentrations  of  specific  chemical   constituents  are  within



prescribed  limits,  and  to  measure   the  effectiveness  of  corrective



actions.   In  general,  contaminant monitoring program approaches  are  of




two types.    '                •.'..:.-.                     (



     The generic approach requires the determination of parameters indi-




cative  of  gross disruption of the  inorganic or  organic chemistry of sub-



surface  conditions [e.g. pH,  solution conductivity (Q~1), total organic




carbon  (TOG)  and total  organic halogen  (TOX)].   It is a  low cost ana-



lytical  alternative,  generally  applied in  detective  monitoring situa-



tions.   The rationale is that  these  surrogate  parameters will indicate



the  impact of  waste releases to  ground-water  systems and  suggest the



identity of the  major  classes of: the  chemical  constituents  involved.



The  usefulness of  pH  and, Q*"1 have been .mentioned above  in relation to



their   importance   to  total  dissolved  solids   content   and  major  ion




 chemistry of  ground-water samples.,.



      Prior to the detection of water quality changes and  in  the  absence



 of  a  complete  mineral  analysis,   the  usefulness   of   the  indicator



 parameter approach is limited.  This is especially true for  TOG  and TOX



 determinations which are nonspecific  and are limited in sensitivity.

-------
     Sample  collection: and  handling precautions  must be  optimized to



 insure  that  the volatile  and nonvolatile fractions  of  both TOC and TOX



 are recovered  quantitatively  (47).  Otherwise, the significance of these



 generic  parameters  may,  be  misrepresented  and   systematic  errors  in



 sampling or  analysis  will  negate their  utility as diagnostic tools.  It



 should  be pointed out .that the use of TOC and TOX  as pollution indicator,



 parameters  can "enhance the  interpretative power  of  observed  data on



 specific contamination  distributions  at  substantially   lower  cost.   The



 trade off,  of  course,  is  that  transformations of  specific volatile or



 nonvolatile  contaminants   may  go unobserved.   The second contaminant



 monitoring  approach focusses on a more  specific set  of  chemical  con-




 stituents.                 ••••..,.•




 Specific Chemical Constituents




     Several  alternative' approaches  to  generic  contaminant 'monitoring



 program emphasize the sampling  and determination  of specific  mobile or



 persistent chemical constituents.   The   selection of  parameters  may be



 limited to those identified by law  (e.g.  Interim  Primary Drinking Water



 Standards  or  Resource Conservation and  Recovery  Act—Appendix  VIII



 parameters, etc.) or may be  based on the actual  composition of  a regu-



 lated facility's waste streams.        i



     The  use  of  a''specific ' list  of chemical  constituents  should  be



 approached cautiously.  The determination of a legally  mandated suite of



 parameters tends to fdciis  primarily on specific classes  of compounds in



wide usage as starting"materials for manufacturing or commercial product



formulations.   'This type  of  program has' definite  advantages,  particu-



larly in situations Where the spill' or release ofa product occurs (48).
                                   42

-------
However,  detailed  investigations of  organic compound distributions  in




environments contaminated by organic mixtures disclose that  by-products



or  substituted  congeners  of  "priority-pollutants"  may be  the  major




mobile  and  persistent  constituents,  while those parameters mandated  by




compliance programs may be present only as minor trace components (49).



     in situations  where the  original  waste components  or  contaminant




mixtures  are  known,  it is preferable to  consider  the relative mobility




and  persistence  of  the known components,  as well as potential transfor-



mation  products.   This mode  of parameter  selection demands  a reasonable




understanding  of the situation under investigation.  Most  of the stan-



dardized procedures for sample  collection,  handling and analysis which



function well  in the initial phases of an  investigation may have to  be



modified to insure control  of errors when  applied to specific  contami-



nants  (-18,50,51).   Once the  likely  suite  of  target  chemical constituents



has  ,been developed,  the  sampling  and analytical  protocols  should  be




 thoroughly reviewed and modified appropriately.                       .



      It  is important  to keep  in  mind  that  sampling   errors  will  be



 carried   over  into  the analytical  operations which follow.    Generic



 sampling  protocols  recommended for  use  in, ground-water investigations



 (52) should be proven to be compatible with the analytical  procedures by



 careful  consideration  of  accuracy,  precision,  sensitivity  and complete-




 ness performance guidelines (26).



      In  order to maximize the cost-effectiveness  and flexibility of the




 initial  planning  of  a ground-water sampling  program,  it  is  useful to



 anticipate that the degree of  analytical  detail  required  will increase



 as .the investigation proceeds.   Therefore, it   is wise to  prepare the



 sampling protocol  for  the most  troublesome  chemical parameters which may
                                     A3

-------
be of interest and maintain close  control  over  the  sampling  operations.



Volatile organic  compounds  (e.g.,  benzene and  trichloroethylene)  which



are soluble  and frequent early  indicators of more persistent  contami-



nants are a  good  candidate  group of chemical constituents on which  the



sampling protocol should  be  based.  The principal  errors introduced  by



the  sample  collection  mechanism,  materials'  exposures   and   sample



handling are due to degassing or  volatilization and  sorption  or  leaching



effects.  These errors are common to those involved  in accurately deter-



mining  major  ion chemistry, TOC,  TOX,  trace inorganic and  nonvolatile



organic constituents to varying degrees, depending on  the  speciation  and



analytical sensitivity  for  the  chemical  contaminants  of  interest.   In



general, sample collection errors are systematic and directly affect  the



accuracy of all subsequent analytical results.



     An inappropriate sampling mechanism  (e.g.  air  lift mechanisms  for



volatile or  gas sensitive parameters) can  yield consistently inaccurate



and useless results.  The  literature provides  valuable guidance  in  the



choice of appropriate sampling mechanisms  and materials once the  param-



eters of interest are idehtified with an emphasis on  the  more challeng-



ing  problems  posed  by  organic  compounds  (52,53).  It  is  clear that



sampling mechanisms  which minimize gas  exchange or materials'   effects



and permit well head determinations of  pH, Eh,  fi~1  and temperature  are



those of choice for most detailed sampling programs.  Sampling protocols



are an active area of research,  but one  should keep  in mind that  it will




cost less over the  long-term if  the investigation  is  planned correctly



to meet information needs.  High quality data merit  the time  and expense
                                   44

-------
of detailed interpretation.  Invalid or  biased  data,  on the other  hand,



are expensive to  evaluate  and  ultimately damage the  credibility of  the




program.




Minimal Analytical Detail for Ground-Water Monitoring Programs



     The minimum  data set, sufficient to the information needs of  the




monitoring  program,  is  defined by both  geochemical and  hydrologic con-



siderations.  Once the  set  of  routine  data elements necessary to define



the  situation at  hand  have  been established,  sampling frequency  and




completeness  requirements  will dictate the dimensions  of the data set.



For  optimum data recovery and facile  data  interpretation,  it is impor-




tant  to define  the size of the  data set and  allow for expansion of the




elements  of interest.   Computer assisted  sample    tracking procedures



incorporated  into the overall  data management system  (including analyti-



cal  data handling) can  facilitate data validation and trend analysis.



      The following recommended data sets  have been developed to coincide



with detective,  assessment  and remedial  action evaluation program  goals.



They provide a  degree of  analytical  detail  which can be  checked for




internal  consistency.   This  is  important to  assure  that  the highest



quality data are produced which  are commensurate  with the  manpower and



fiscal  investments that high quality data collection  demands.





Detection  Monitoring Data  Set



      The  minimal data  set  for a monitoring program designed for  future



 detection of contamination should provide the base level of  information



on hydrologic and chemical conditions at a site.   The  parameters iden-



 tified below will permit mass and  charge balance  checks on  the consis-
                                    45

-------
 tency of the data and will provide valuable information on  ground-water



 chemistry.   In this manner, the  ability to identify  "missing"  charged



 constituents,  which may  be  contamination related, can  be established.






                            Chemical Parameters



           pH,  fl-1,  TOG,  TOX, Alkalinity,  Total Dissolved Solids



           Eh,  Cl~,  N03~, SOU",  P0n=, Si02



           Na+, K+,  Ca++, Mg++,  NHz, + , Fe, Mn
                          Hydrologic Parameters



                   Water Level, Hydraulic Conductivity






     This  level of  detail  provides  the basis  for  solution  chemistry



composition calculations which are important for predictions of contami-



nant speciation, mobility and persistence.




Assessment Monitoring Data Set




     The minimal  data set for  a  monitoring program  designed  to  assess



the type  and extent of  contamination  incorporates the level  of  detail



noted in  detective monitoring situations and indentifies  potential con-



taminants of concern.  The actual suite of potential contaminants  may be



stipulated by regulation in some instances.






                           Chemical Parameters



          pH,  fl-1,  TOC, TOX,  Alkalinity,  Total Dissolved Solids



          Eh,  Cl~,  N03~,  S0n = ,  P0i|-,  Si02,  B



          Na+,  K+,  Ca+\  Mg++,  NHi,*,  Fe,  Mn



          Fe(II),  Zn, Cd,  Cu,  Pb,  Cr, Ni



          Ag,  Hg,  As, Sb,  Se,  Be
                                   46

-------
                          Hydrologic Parameters



                  Water Level,  Hydraulic Conductivity






The realm of potential organic contaminants in ground-water  systems  must




be delimited based on the nature of  the  likely contaminant  source.   The




priority  pollutant  analytical  scheme or  selected  categories  of  RCRA



Appendix VIII parameters should be a good starting point when other  data




are unavailable.






WELL PLACEMENT AND CONSTRUCTION



     The  placement  and construction  of  monitoring wells .are among the



most difficult decisions involved in developing an effective monitoring



program.    The  preliminary  locations and depths  of  monitoring wells




should be selected based on  the  best available pre-drilling data.   Then



as the  actual  installation  of these wells progresses, new  geologic and



hydrologic  data should  be incorporated into  the overall  monitoring  plan



to insure that the finished  wells will  perform the tasks for which  they



are designed.  In most  instances,  it is probably  advisable  to  select  a



minimum  array  of monitoring wells  for  the  collection of  geologic and



hydrologic  data.  Then  additional wells  can  be designed and constructed



to more effectively meet the goals of the monitoring program.



     The  positioning  of a monitoring  point  in a  contaminant flow  path



must  be determined on  the   basis  of hydrologic  data.;   Therefore, the



contaminant  flow  path must  be  clearly defined  in three  dimensions.



Special  emphasis must  be  placed on the  collection of  accurate water



level data  as well drilling  and construction progress.   For example, the



level at  which sand heaves  up into  the borehole is often related to the



depth  at which  the  vertical  movement  of  ground  water is upward  as
                                    47

-------
opposed  to the normally  assumed downward migration.  Accurate  measure-



ments of stabilized water levels from an established reference elevation



is  essential  to understanding the  flow  paths of ground water  and  dis-



solved constituents.                                                  .



     The  construction  of monitoring wells  should be accomplished  in  a



manner that minimizes the disturbance of the materials in which the  well;



is  constructed  (3).  If  the  monitoring  program calls for determinations



of  organic compounds, care should be taken to steam clean the drill  ,rig



and all other equipment and well components prior to mobilization to the



site.   Repeated  cleaning of  drilling  equipment and  well-construction



materials  at  the  site  also is  necessary.    The drill  rig should  be



checked  for hydraulic  fluid and  oil  leaks prior  to the initiation  of



drilling.  These  preliminary precautions  are essential to  insure  that




artefacts of the drilling process are not  detected later  in  the program



and  considered  to be the result  of actual conditions at the monitored



facility.



     The selection  of  the type of  drilling equipment should depend  on



the type of geology present-, the  expected depths of  the wells,  and the



availability of equipment in  the location of  interest.   However,  the



availability and relative costs of different types of drilling equipment



should  not be  used as  the  primary  selection  criteria.    The use  of



specialized drilling techniques  may have real  advantages  for even  the



most preliminary site investigations (50).





Drilling and Well Completion Methods



     The selection of drilling and  well  completion methods for  monitor-



ing well construction has been approached traditionally  from considera-
                                   48

-------
tions  of  the  type  of  geologic  materials  to   be   penetrated,   the



anticipated  depth  of  drilling,  and  the availability  of  construction



equipment and materials.  Little attention has been  given  to  the  poten-




tial  adverse  chemical  effects  of  the  drilling and well, construction



procedures on the samples produced  from the  monitoring well.   This guide




discusses several drilling methods in terms of the  suitability  of their




application for  monitoring  well construction.  Detailed  discussions of



drilling procedures and rigs are presented in other  references (3,54).



     The  selection  of  an appropriate  drilling method  for constructing




monitoring wells should be  based on minimizing both the  disturbance of



the  geologic  materials penetrated  and the introduction of air,  fluids,



and  muds.    The  use  of organic drilling muds or  additives should be



avoided.  The introduction of any foreign material has the potential for•



interfering with the  chemical quality of water obtained  from the moni-



toring  wells.    Based on these factors  and  the  physical  limits  of the



various  drilling methods and rigs, the  following evaluations  have been



made  of  the more commonly used types.



      A  summary of  recommended  applications  for various  drilling tech-




niques  is presented in  Table  2.1.




Hollow-Stem Continuous-Flight Auger



      The hollow-stem  continuous-flight  auger  rig  is  among the  most



desirable drill  rigs  for the  construction of monitoring wells.  The rigs



are  generally mobile,  fast, and inexpensive to operate in  unconsolidated



materials.   No  drilling fluids  are used and disturbance to the geologic



materials  penetrated  is minimal.    However,  augers  cannot be  used in



consolidated rock and most  rigs are limited to drilling to approximately
                                    49

-------
             Table 2.1.  Recommended
                    Various Types of

Geologic Environment

Glaciated or unconsolidated
materials less than 150 feet
deep
Glaciated or unconsolidated
materials greater than 150 feet
deep

Consolidated rock formations
less than 500 feet deep (minimal
or no creviced formations)
Consolidated rock formations
less than 500 feet deep (highly
creviced formations)

Consolidated rock formations
more than 500 feet deep (minimal
or no creviced formations)
Consolidated rock formations
than 500 feet deep (highly
creviced formations)
 Drilling Techniques for
Geologic Settings

 Recommended Drilling Technique

 (1)   Hollow-stem continuous-flight
        auger
 (2)   Solid-stem  continuous-flight
        auger
 (3)   Cable tool

 (1)   Cable tool
 (1)  Cable tool
 (2)  Air rotary with casing hammer
 (3)  Reverse circulation rotary

 (1)  Cable tool
 (2)  Air rotary with casing hammer


 (1)  Air rotary with casing hammer
 (1)  Air rotary with casing hammer
                                    50

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45.5 m (150 feet) (3).  In formations where the bore hole will  not  stand



open, the  well is  constructed  inside the  hollow-stem  augers  prior  to




their removal  from the  ground.   This limits  the  diameter of the  well



that can be constructed with this type of  drill rig to  about 10.16  cm(4



inches).  15.24 cm (6-inch inside diameter augers  are available for  this



purpose.  The use of hollow-stem auger drilling in heaving sand environ-



ments also presents some difficulties for the drilling  crew.  However,



with care and the use of proper drilling procedures, this difficulty can




be overcome.





Solid-Stem Continuous-Flight Auger



     The use  of  solid-stem continuous-flight  auger  drilling techniques



for monitoring well construction is limited to relatively fine  grained



unconsolidated materials that will  maintain  an  open  bore  hole.    The



method is  similar  to  the hollow-stem continuous augers  except that the



augers must  be removed  from  the ground  to allow the  insertion of the



well casing and screen.  This method is also limited to a depth of  about



45.5 m  (150  ft)  and does not lend  itself  to  collection of soil  or  for-



mation samples.  This type of drilling method is a poor second  choice to




the more desirable hollow-stem auger methods.





Cable Tool



     The cable tool type of rig is relatively slow but still  offers many



advantages that make  it  the second  choice for monitoring well  construc-



tion  in  unconsolidated  formations  and the method  of  choice  for  rela-



tively  shallow consolidated  formations.    The  method  allows  for  the



collection of excellent formation  samples  and detection of even  rela-



tively fine grained permeable zones.  The installation of a steel casing
                                   51

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as drilling progresses also provides an excellent temporary host for the



construction of a mbnitoring well once the desired depth is reached.



     As  stated earlier,  the method  is  slow and small  amounts  'of water



must be  added  to  the hole as drilling progresses until  the water table



is  encountered.  However, 'the' quantity  of water -added to  the  hole and



into the formation  to  be sampled is  minimal.   A drive  pipe diamet'er of



10.16  cm (^ inches)' may be too small  for the  easy construction  of  a



5.08  cm  (2-inch)  diameter well.    It  is  recommended  that  a  minimum



15.24  cm (6-inch)  diameter drive pipe be used to'facilitate the place-



ment of  the well casing, screen, and gravel pack, and a minimum 152.4-cm



(5-foot) long bentonite seal prior to beginning the removal of the drive



pipe.   The placement  of a bentonite seal  in the  drive pipe  prior to



pulling  will assist  in holding  the gravel  pack,  well casing,  and screen



in place.   The seal will also'  isolate the  gravel  pack  and screen  from



the cement seals above.  The drive pipe'is pulled in small increments to



permit  the  bentonite seal to  flow  outward and  fill the  annular  space



vacated  by the drive  pipe.   The drive  pipe also  is  pulled'  in< small



increments  as  cement grout material  is  added to  ensure that.  a satis-



factory seal is obtained.-                      -





Air Rotary



     Rotary drilling methods operate  on the  principle of circulating



either a fluid or air  to remove  the  drill cuttings  and  maintain an  open



hole as  drilling progresses.  The different types of rotary drilling are



named  according to  'the type of fluid and  the direction of fluid  flow.



Air rotary drilling  forces air  down  the  drill  pipe  and  back up the  bore
                                   52

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hole to remove the drill cuttings.   The use of air rotary drilling tech-



niques is best suited for  use  in hard rock formations.   In soft  uncon-



solidated formations  a  casing is   driven  to  keep  the formations  from




caving.  Similarly, in highly creviced formations it is often   difficult



to maintain air circulation.  Air rotary drilling appears to have  poten-



tial ,for  constructing monitoring wells without adversely affecting the



quality  of  water  from  monitoring  wells  in  hard rock formations  with



minimum unconsolidated overburden.   The successful construction of moni-



toring  wells using this drilling techniques is dependent on the ability



to maintain an open bore hole  after the  air circulation ceases.   If the




wells are, intended to monitor for organic constituents, the air from the



compressor on the rig must  be  filtered to  insure  that  oil from the com-



pressor is not introduced into the.geologic system to be monitored.  The




addition  of  foam to the circulating air is  often  employed to increase



the  effectiveness  of air  drilling  techniques.  Most  of  the  foam addi-



tives  contain organic  materials which  may interfere  .with both organic



and  inorganic constituents  in samples  collected from  the  constructed



monitoring wells.   The  use of  air  rotary drilling techniques should not



be  used  in  highly  polluted  or  hazardous environments.   Contaminated




solids  and water are blown out of   the hole which are  difficult to con-



tain.   Protection  of  the  drill  crew and  observers  is  correspondingly




very difficult.




Air  Rotary With  Casing Hammer                  -..-••



      Air  rotary drilling  with casing driving capability increases the



 utility of  this  type of drilling method.   The problems  associated with
                                    53

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drilling  in soft unconsolidated and highly creviced formations are mini-



raized.  The utility of constructing monitoring wells in the casing prior



to pulling it also makes this type of drilling technique more appealing.



However,  the same concerns  about  the  oil  in  the circulating air and the



addition  of  foam  additives must  be  considered.   Grouting  and  casing



pulling  procedures  similar to those  described  for cable  tool  drilling



methods should be employed.





Reverse Circulation Rotary



     Reverse circulation rotary drilling has  limited application for the



construction of monitoring  wells.  Large  quantities  of  water  are circu-



lated  down the  bore  hole and pumped  back to the surface  thru the drill



stem.  The hydrostatic pressure of the water in the bore hole is used to



maintain  an  open bore hole.   If permeable  formations  are encountered,



large  quantities  of  water  will  infiltrate   into  those  formations



altering  in  situ water  quality.   Similarly, water  bearing  units  with



differing hydrostatic  heads will have  the opportunity  for free  inter-



change of waters altering  the  quality of  water in the  unit  of  lower



hydrostatic head.   Because  of  the large  quantities  of water  normally



required for this type  of  drilling and the  high potential for  water  to



enter  'the formations  to  be sampled,  this   type of  drilling  is  not



recommended.




Mud Rotary



     Mud rotary drilling operates in  the same fashion as  the  air  rotary



drilling technique except water  and drilling  mud are  circulated down the



drill  pipe and  back  up the bore hole to remove  the drill  cuttings.  The



bore hole is held  open by  the hydrostatic  pressure  of the  circulating
                                   54

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mud  and a  mud cake  that develops  on the  bore hole  wall  during  the



drilling process.   The viscosity   of the drilling mud  is  controlled to



minimize the  infiltration of the.drilling fluid  into .porous  formations




penetrated by the drilling equipment.



     The  construction of monitoring  wells  using,  mud  rotary  drilling




techniques is very difficult.  The well must  be  constructed  in  the bore




hole which  is still  filled with drilling mud.   This makes it difficult



to  determine  where gravel  pack materials terminate and the well seal



begins.  After monitoring wells  are  constructed,  they must be developed




to  produce  visually clear water  which will  facilitate field filtration.



Breaking  down the mud  cake and removal  of  all mud introduced  by this



drilling technique is extremely difficult when small diameter monitoring




wells  are  being constructed.   Experience has shown that  drilling mUds



not effectively removed from  the well  bore opposite the  screen  and




gravel pack will  interfere with the  chemical  and biological quality of




samples from those wells (55,56,57).   Many  clay or  synthetic drilling



muds contain  organic matter  (e.g., polymers, pqlyacrylamide or starches)



which can  also greatly effect  the  organic content of water obtained  from



mud rotary drilled wells  (23,W.    For these  reasons,  the use of mud



rotary drilling methods  is not recommended, particularly for investiga-




tion of organic contaminant  situations.





 Bucket Auger



      Bucket auger drilling  rigs are usually employed  for the construc-



 tion of shallow large diameter wells or caissons.  Their  use is limited



 to fine grained formations  that are capable of supporting an open  bore



 hole. The large diameter  created  by this type of  drilling technique  is
                                    55

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 not usually warranted.   The use of hollow-stem continuous-flight auger



 techniques can  be more  effectively  employed  in  appropriate  geologic



 environments.





 Jetting




      Jetting of  monitoring wells  is  not a common practice in most of the



 United States.   Little or no information is obtained  on the materials



 thru which the  well is  jetted.   As  with  the reverse rotary  drilling



 technique,  water used in the jetting  process  also enters the formation




 to be monitored and  alters   the  in situ water  quality.   This  type of



 drilling technique  is not recommended  for monitoring well construction.




 Driving




     Driving  of  well  points and  casing  may  be  acceptable  in  certain



 hydrogeologic environments.   As with jetting, little or no information



 is obtained on  the materials through which  the  well  is driven.   This



 type of  well construction should be  limited  to relatively shallow (less



 than  15.17  m  (50 feet)) homogenous  sand and  gravel  formations.   Due to



 the  nature of this geologic  environment,  no well  seals  are  normally



 required.





 Monitoring Well Design




     The  effective  design of monitoring wells requires careful  consid-



 eration  of  the hydrogeology  and subsurface  geochemistry at a site.  The



 information obtained  from preliminary borings or  well   drilling can  be



most useful in making logical  decisions on  the drilling,  construction



 and  development  methods which are appropriate for the  program's  goals.



The design of a monitoring well should not be based on  the  most readily



available   types of  drilling equipment  or    that  used  by  the favorite
                                   56

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driller in the area where the  project  is   located.   Cost considerations



alone should be'secondary to the retrieval of valid data which will meet



the goals of the program.  Apparent cost savings realized  by  expedient


well construction may have a serious impact on the quality of the hydro-


logic and chemical data  produced from  the monitoring  effort.  The well



design  goal  should be to  construct  wells that  will produce  depth and


location specific  hydrologic and   chemical  data..   Precautions  must be



taken to insure   that well  completion .and development  procedures mini-



mize the, disturbance to the  geologic environment and the water samples.


     Wells constructed for  the production of large  quantities  of water



normally are  not  satisfactory for  use as  monitoring wells in detective


or  assessment type monitoring   programs.   These wells  are constructed
          1      •   •  .' ;    '       "'••..   -     , -1 ! - '    ' •


with long sections of well screen or open  bore holes designed to produce


water  from  large  vertical and horizontal  segments  of the aquifer mate-



rials  tapped.   The  resulting chemical quality of water pumped from the



wells represents an integrated chemical quality from all sections of the


aquifer  contributing water  to the well.   Without  knowledge   of   the



vertical  and  horizontal  contributions   of  water  to  the  well,   these


chemical  data have  little   value  aside  from indicating  the quality of


water  produced  by  that well.  A potentially large amount of  dilution of


any relatively small plumes  (relative to  the size of the  pumping  cone)



intersected  by the pumping  cone of the well could effectively mask the

              ' •     ' -    •'           ' •"  r.... •• . . ."  ,"-•  -   •'   ." -        - • '• -
presence  of  the plume.   Similarly,   the hydrologic data  obtained  from


these  types  of wells   represents  an  integrated water  level  for the
                                    57

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 vertical  segment  of  the  aquifer open to the well.  The hydraulic conduc-



 tivity data represent integrated  values  for the segments of the aquifer



 influenced  during the  course of the pumping test.
                                                                ij



 Depth of  the Well



      The  depth of a monitoring well  should be  determined  based  on the



 geology and hydrology of the site and the  goals  of  the  monitoring pro-



 gram.   In  most monitoring programs the goal is to monitor the potential



 effects of  near   surface activity.  Therefore,  it is essential to docu-



 ment  and  monitor  the downward migration of potential pollutants that may



 be  leaking  from the facility.  As  percolating water and  their solutes



 move   into  the  saturated  zone,  local   and  region  flow  systems  are



 encountered that  will  impart  a  horizontal component  to the migration of



 the pollutants.



      To properly  define the movement of pollutants,, vertically and hori-



 zontally, it is  essential to collect  depth discrete water  level  data.



 The uppermost  relatively permeable zone  will  provide  part of  the  data



 needed  to  determine  the vertical  direction  of  ground-water  movement.



 The  shallowest monitoring  wells  in  the monitoring system .should  be



 finished  in these materials.  Water levels from these wells,  if finished



 in the  same geologic materials,  will provide information  on theihorizon-



 tal directions of  shallow  ground-water   flow.    In  unconfined aquifer



 systems this will  represent  the  "water  table."   In  confined aquifer



 systems it  represents the  piezometric surface of  the  shallowest  per-



meable  zone.
                                   58

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     Additional wells  at  the same locations  but  at greater depths  are

needed to complete the data set needed to  determine the  vertical  direc-

tion of  ground-water  movement.    These wells  should be finished  in  the

next  deepest  relatively  permeable  zone  in  a geologic  setting  where

interbedded permeable  and nonpermeable zones  are   present.   In geologic

settings where  the  materials are: relatively  permeable and  uniform with

depth, the screens  of  adjacent  wells should be staggered at an interval

equal  to  one  to  three  times  the  selected  screen depending  on  the

vertical  detail necessary  to define  contaminant  distributions.    This

vertically-nested well depth approach should be continued  at  each well

location; until  water  level  data indicates  that the potential for  deeper

migration  of  surface derived  pollutants is minimal.

     The  required  number  of vertically nested wells and  their  depths

also will  be  a function of  the relative horizontal to  vertical  permea-

bilities  of  the formations beneath  the site  and  the hydrologic  setting

in which they  are  located.  The  optimum  approach  is to  ensure that the

vertical  locations  of the well screens are at the most likely depth to

intersect  pollutants from the facility being monitored.   An example is

presented below to  illustrate the application of this type  of monitoring

well  design  approach.

Example  2.1.    Selecting  depths  for  vertically  nested  wells   in an
alluvial river valley setting—

      Site background:
           The  site  to be  monitored lies  on the  banks  of a
           major river.   Regional  information indicates that
           the  unconsolidated materials  are  sand  and  gravel
           from the  surface to the  underlying bedrock,  about
           120  feet.   Regional water  levels vary from about 15
           to 25 feet  below land  surface.   The activity  to be
           monitored  is  a  small  metal  plating facility that
                                    59

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        uses a lagoon for disposal of its wastes.  The rela-
        tive specific  gravity of  the  wastes is  similar  to
        that of  the native  ground water.   No  hydrocarbons
        are associated with the wastes.

   Preliminary well construction:

        Locations for  vertically nested wells were selected
        at one upgradient and three  downgradient locations.
        Two wells,  one about  five feet below the seasonally
        low water table elevation and  one approximately ten
        feet deeper, were constructed at each location.  The
        wells were  all equipped  with two-foot long screens.
        The wells  were developed, elevations of  the casing
        tops  (water level measuring  reference   point)  were
        surveyed to the nearest  0.01 feet,  and  water levels
        were measured to the nearest 0.01 feet.

   Preliminary water level analysis:

        The  following  list   presents   the   construction,
        elevation,  and water  level data  obtained .from this
        preliminary and a subsequent second drilling effort.
Well no.
BG-1
BG-2
DG1-1
DG1-2
DG2-1
DG2-2
DG3-1
DG3-2
Depth
below
land
surface
32.0
42.0
26.0
36.0
27.0
37.0
26.0
36.0
Land
surface
elevation
349.27
349.27
344.11
344.11
343.42
343.42
339.73
339.73
Elevation
midpoint
screen
318.27
308.27
319.11
309.11
316.42
306.42
313.73
303.73
Measuring
point
elevation
352.00
351.85
346.69
346.53
345.97
345.78
342.71
342.59
Water
level
below
MP
22.00
22.65
23.29
23-73
23.89
24.18
22.61
22.61
Water
level
elevation
330.00
329.20
323.40
322.80
322.08
321.60
320.10
319.98
Second drilling effort:

DG1-3      46.0     344.11
DG2-3      47.0     343.42
DG2-4      57.0     343.42
DG3-3      46.0     339.73
DG3-4
56.0
339.73
299.11
296.42
286.42
293.73
283.73
346.37
345.53
345.29
342.31
342.17
23.62
24.11
24.19
22.26
21.97
322.75
321.42
321.10
320.05
320.20
        At each  of the  vertically nested  well pairs,  the
        direction  of  ground-water  movement  is  downward.
        Plotting the total hydraulic head (water level  ele-
        vations)  at  the midpoint  of the well screens  and
        constructing  flow  path  lines   from  the   proposed
        lagoon  facility  suggests  that  deeper wells   are
        required at DG1,  DG2,  and DG3.
                                 60

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     Second drilling effort and analysis:
         One  additional  well was constructed at  DG1  and two
         additional  wells were  constructed at DG2  and DG3.
         Data from  those wells  are included  in the  above
         table.   Plotting the  total hydraulic heads  at the
         midpoints of  the well  screens  and constructing flow
         paths  suggests  that these  wells  should  be adequate
         for  monitoring  potential  leakage, from  the lagoon.
         Figure  2,9  illustrates  the   analyses  of  data and
         plotting  of  vertical  and horizontal   flow   paths.
         From this  preliminary  data,   the  appropriate wells
         for  sampling  and chemical  analysis can be selected.

         As  a final word of caution,  this planning and con-
         struction effort was accomplished  during a  period of
         low  water levels;  data from  periods  of high water
         levels  should be examined  to  determine  if  the same
         well configuration is  adequate.  Similarly,   these
         analyses  were conducted  prior to the influences of
         leakage from  the  lagoon.   The same  type  of  water
         level  analyses  should  be  performed periodically to
          insure  that the monitoring program remains  effective
          in meeting  the  intended goals.

     In addition to the  general  guidelines noted above, wells  intended

for  use  in  monitoring  hydrocarbon pollutants that are less dense  than

water  and  likely to float on the  water table surface  should be  con-

structed so the well screen  is always open  to  the water table.  If  the

water  table is  known to  fluctuate  several  feet  over the course of  the

year, the screen will have to be long enough to accommodate  those  fluc-

tuations.

     The design of monitoring wells for  sampling sites  contaminated with

immiscible hydrocarbons  or hydrocarbon  products  more  dense than  water

also  warrants special consideration.    A  well  screened throughout  the

entire  thickness  of  the  aquifer  potentially  affected  appears  to  offer

the  best potential  for  adequately  addressing  this  type of  monitoring

problem  (58).  Wells constructed in this manner and  properly sampled to
                                    61

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   BG
                     Proposed

                     Lagoon
                        DG1
              DG2
      —;	Li   j
      An  ^           —--^^ —*— —.
    30.00 /

       /        S~

    29.20    /







'   /      '
    A      /
        /
                               Seasonal low

                                .water table


                           — jL	 ___
/
                      ->£ 122.E


                   ,  /  >,

                   / ^^122.75
                                        /
80 ^ ^^ /   121.60  /
                                                                       DG3
               F22.08
                  /
      •v.
         /
    ^     <^?
           
-------
minimize the  vertical migration of  non-aqueous  phases within  the  well


should  provide reasonable  indications  of the vertical  distributions  of


hydrocarbons in the aquifer system.


Diameter of Monitoring Wells

     The  diameter of  a monitoring  well casing should be held  to the


minimum practical size which will  meet both the  strength requirements


for  the  anticipated  well  depth  and  the  size  of  the  sampling  pump


required to deliver water  samples  to the surface.   Studies by Gibb (11)


have documented that  the water held  in  storage in the well casing under-


goes chemical  change  while in the  well casing.   When pumping begins for


sample collection, some of this  chemically altered water will be  brought


to the surface along with water from  the formation  being sampled.   The


relative  quantity is  related to  the  hydraulic conductivity of the forma-


 tion being sampled,,  the rate  at which the well is  pumped and the size


 (diameter.) of the  well casing.   The  amount of water  removed from the
   '     -   -            '.!"'

well casing is a function of the formation hydraulic properties  and the


 pumping rate.  Therefore, as the diameter of the well  increases, larger


 portions  of  altered,  unrepresentative, water samples  are delivered  to


 the surface to create the same amount of drawdown.   Based on the  availa-


 bility of ground-water sampling'  pumps  capable  of  lifting water  from


 depths as great as 15.17 to 227.50 m (500 to 750 feet), 5.08-cm (2-inch)


 diameter  wells   should .be  used in  all situations  except  where  depth


 requirements   call   for  added material  strength.   Table  2.2 presents


 general depth recommendations for various sizes of PVC, stainless steel,


 and Teflon(R) well casings.
                                     63

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                 Table 2.2.  Well Casing Material Specifications
                              Depth Recommendations
                         PVC
                                              Stainless steel

Nominal
casing
diameter
Wall
thickness
Weight
Ibs/ft
Type of
thread
Maximum
recommended
hang length*
(ft)
Schedule 40


2"

0.154"

0.716

square

3,100


Schedule 80


2 »

0.218"

0.932

square

3,300


Schedule 40 Type 304


2"

0.065"

1.732

fine

11,500




,2"

0.065"

1.732

square

Not
available

A ^J. _U^S* A
Schedule 40


. 2"

• 0.080"

0.9

square

320


* Length refers to total of single material.   Depth range  of 'Teflon(R)  can  be
  extended by casing only the saturated zone  with this material  using another
  material above.  The hang lengths were calculated on the baiss of  the shear
  strength of the threads and the weight of the suspended  casing.
                                       64

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Size of Screen
     The screen  in a monitoring  well  should be  long enough to  permit
entry of water from the vertical zone to  be monitored.   In most  geologic
settings a 60.96-cm (2-foot) long screen  is adequate.   The length  of  the
screen  should  be held to a minimum so that water  level data  obtained
from the well will represent relatively  depth discrete information.   In
wells  where  the length  of  the screen  is long  (152.40  cm   (5  feet)  or
more)  the  resulting water level is an integrated value  representing an
average water level of the materials opposite the screen.
     Tne slot  size of the screen also should  be  selected to retain the
formation  materials  yet  permit  free entry of water into the well.   Since
most  monitoring wells are  not  pumped  at high  flow  rates the available
open  area  of the  screen  is  not usually  an issue as  in  production well
screen design.   In very fine grained deposits a gravel  pack material is
often placed between the screen and the  formation to be monitored.  The
 grain  size  of  the  pack material  should  be  three  to  five  times  the
 average grain size  of  the formation materials.   The  screen slot size
 should be selected  to  retain 90% of  the  gravel pack materials.  When
 Teflon(R)  casing  and  screen are used in  deep  formations,  it  is  recom-
 mended  that a  slightly larger  screen  slot  size  be  used  since  the
 Teflon(R)  will tend to compress and reduce the  effective slot size.  The
 gravel pack materials should be  thoroughly cleaned and  composed  princi-
 pally  of  quartz sand.    Materials  containing  fine grained  clay  or  silt
 sized  particles should  be  avoided.   The  chemical  nature  of  the  pack
 material  should be as inert as possible.  Silica sand or glass  beads are
 recommended.
                                     65

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      For wells where no gravel pack is used, the screen slot size should



 be selected  to  retain 60 to 70%  of  the materials opposite  the  screen.



 The finer portions of  the  aquifer materials are removed from the forma-



 tion during  well development  and a natural  gravel  annul us is  created



 around the well screen.





 Grouts and Seals




      The selection of grouts and seals  for  monitoring wells  is an essen-



 tial consideration to  obtain water samples  that  are  representative of




 in-situ conditions. First,  the  seal  must  be adequate to prohibit.the



 entry of surface water down along the  well   casing.   Similarly,  a good



 seal  must be  maintained  along the entire  length  of  the well casing to




 ensure  that  water from overlying  formations does  not  migrate downward,



 Effective  seals  are obtained by using expanding materials that will not



 shrink  away  from the well'casing after setting.   Expanding neat  cement



 and  bentonite clay or  a  mixture of neat cement  and  bentonite  clay are



 among the most effective materials for  this  purpose.            >



     The selected  seal  also must  not  interfere with the water chemistry



 results.  Bentonite clay has appreciable ion exchange capacity which may



 interfere with the chemistry on collected samples when the grout seal  is



 in close proximity to  the screen or well intake.   Similarly,  expanding



 cement  which  does  not harden  properly  may  affect the pH  of  water  from



monitoring wells when in close proximity to  the well screen or intake.



     To  minimize  these  potential  interferences,  a  30.48-cm  (1-foot)



layer of fine  Ottawa or silica  sand  should  be place above the selected



gravel  pack.  Then, if  possible,  30.48  to   60.96 cm (1  to  2 feet) of



bentonite pellets should be placed in the hole to  prohibit the downward
                                   66

-------
migration  of  bentonite  slurry or  neat, cement.-   The  upper 152.40  to



304.80  cm  (5  to  10. feet)   of the well  casing should  .be sealed  with



expanding  neat  cement  to provide for  security and an, adequate  surface




well seal.  The exact depth  of  the  upper seal  should  be slightly deeper




than the probable  deepest frost penetration. This  will  protect  the well




from frost heaving.                                       .          .





Multiple-Completion Wells



     The  use  of  multiple-completed wells  in  a  singl:e  bore hole has



received much attention in the literature.  However,  the effectiveness



of  the  well  .seals  between  intervening   monitoring .points  is   often




suspect.   Advocates of  multiple  completed wells  in  the same bore hole




suggest .that  pump  tests can  be  used  to verify the  integrity  of  indi-



vidual  seals.   These verification procedures can only be used in situa-



tions where the well completions are not in  hydraulic,  connection.  The



 care  and time necessary to  properly seal  these types  of • wells  are, not



justified when  compared to the  straightforward procedures, for sealing




 separate  holes  for vertically nested wells.





Well  or Sampling Point  Documentation



      The   details  of the  construction of  each well  or sampling  point



 should be  documented  by both a drilling  log and  a well  construction



 diagram.   The  drilling log  should contain descriptions  of  the general



 texture,   color, size and hardness  of  the  geologic materials  encountered



 during drilling.  Figure 2.10 illustrates  a typical log containing these




 types of  information in an easily understandable format.



      Geophysical  (earth resistivity or seismic)' data should be  mapped



 and correlated with data from the soil boringsV  Neutron'or: beta logging
                                     67

-------
RECORD OF SUBSURFACE EXPLORATION
PROJECT-
JOB NO-
                 —	:	:	_  BORING  H"5
                  Monitoring Wells  SHEET j_QF j_
:
Z
a.
u.
a








•10


•15-


•20-


•25-



•30-



•35-
DRILL
DATE
DRILL
LOQG
PIEZO
SAMPLE
NUMBER



1
2
3
4

5



ING
DRI
EDE
EDE
MET
-j
a:P
Un
t-

SS

ss

ss

ss

ss

ss

s
^•••M
METI
-LED
IV
ADVANCED /
RECOVERED (In)

18/16
18/li)
18/10
18/12
18/10
8/12
0/20
^™™™™^»»
DESCRIPTION OF MATERIALS
(Color Modifier MATERIAL. Claislllcallon)
Soil Classification Sy.fsm Un i f j i;d

Surface Elcvillnn -

Dark Gray CLAY, with Si It
Brown Silty CLAY, Trace Fine San
Brown Fine SAND, Dry ' •
Brown Fine Silty SAND
Brown Fine, to Medium SAND
36' TOB
BLOWS
(per 6 In;
5-7-10
4-5-6-'
5-6-6
2-3-8
6-8-11
6-8-1 1
-11-12
DRY UNIT WEIGHT (pel) I






4on HOI iipw Auoers ^^^.
12-17-82 ~ 	 GR°l
• 	 	 	 	 _ —El*
~ 	 	 	 	 	 	 — • • •'• 	 Ho
EH^ See Sketch 	
Shear Strength, tsf
SVA QP/jD OU/iO
?.'(', 1 . 1'A 2 2V.
PL NMC LL
* • Y
0
t^
50 100
laj^aji Rock Quality Dttlgnilion


































































.





























JNDWATE
countered, al
tin after con
after con
after con
































































































R LEVELS
19.0
nplctlon
npletlon
npletion
















































Feet
Feet
Feel
Feel
     Figure 2.10.  Drilling log sheet
                 68

-------
results may also be included on the logs of the  bore holes  investigated.
Natural gamma ray, gamma-gamma density (Cesium-MST source);,  and electro-
magnetic induction  logs  can be run  inside plastic casings as  small  as
5.08  cm  (2 inches) in diameter  and in some  cases may be  adequate  and
more  cost  effective than  collection  of  core samples for  describing geo-
logic conditions.  Use of these techniques should be compared or truthed
with  a  minimal number of core samples  for visual and laboratory exami-
nation.  In all  cases, the dates of  all activities should be recorded to
permit the reconstruction of the development of- site understanding.
      Data  summaries  in  the  form  of  geologic cross-sections  are often
very  useful in developing a  visual presentation of  the subsurface condi-
tions.   However,  caution must'be exercised in interpolating between data
points    (soil  borings).    In  very homogeneous  geologic  environments,
extrapolations of data for tens to  hundreds  of  feet may be acceptable.
In more  heterogeneous  environments, extrapolation of data  should not
 exceed a  few  tens  of feet.   To assess the relative homogeneity of the
 geologic  environment,   site specific  data  should  be   evaluated with
 respect to regional geologic information.   No site description should  be
 considered complete without an indication of the geologic variability  of
 site conditions.
      Once the  bore hole is  completed and  well  construction is underway,
 the  data  necessary for  documenting  well  completion should  be  collected.
 The  data  items shown in Table  2.3 should be used to prepare a well con-
 struction diagram.
      This information on well  construction can  be  summarized on a one-
 page  diagram  similar to that shown in Figure  2.11.  Geologic and pre-
 liminary  water level data also should  be included for, completeness.  The
                                     69

-------
Table 2.3.  Data Needed for a Monitoring Well Construction Diagram

              Date/time  of  construction
              Drilling method
              Well location (±0.5 ft)
              Bore hole  diameter
              Well depth'(±0.05 ft)
              Casing material        ;
              Screen material
              Screen slot size/length
              Gravel pack type/size  (depths from 	 to 	)
              Grout/sealant used (depths from 	 to      )
              Backfill material (depth from       to
              Surface seal detail (depth from 	
              Well protector type
              Ground surface elevation (±0.01 ft)
              Well cap elevation (±0.01 ft)
to
                               70

-------
                              4" Well Protector






                              Concrete Cap
                              Soil Backfill from Cuttings
                              Granular Bentonite
                              Filter Gravel
                              2" PVC Riser Pipe with Cap
                              Sand  Cave-in
                               2" PVC Well Screen with 0.006" Slots
Figure 2.11.  Monitoring well construction diagram
                         71

-------
 water level data should  indicate the length of  time  the  bore hole was



 open prior to the water level measurement.   This information should not



 be  considered to be representative of the final level water reflected by



 the finished well.  The effects of well trauma and gradual equilibration



 of  water levels  in newly-constructed wells limit the  value  of initial



 water level measurements  (59).






 WELL DEVELOPMENT, HYDRAULIC PERFORMANCE AND PURGING STRATEGY



      Once  a well is  completed, the sampling point must  be prepared for



 water sampling  and measures  must  be  taken to  evaluate  its  hydraulic



 characteristics.  • These  steps  provide  a basis  for  the maintenance  of



 reliable sampling points  over the duration  of  a  ground-water  monitoring



 program.





 Well Development




      The  proper  development  of  monitoring wells is  essential to  the



 ultimate   collection  of  "representative"  water  samples.  During  the



 drilling process,  fines are  forced through the  sides of  the  bore hole



 into the formation, forming  a mud cake that reduces the hydraulic con-



 ductivity of the materials in the immediate  area  of the  well   bore.   To



 allow water  from  the formation  being monitored to freely enter into  the



 monitoring well, this mud cake must be broken down opposite the screened



 portion  of  the well and the fines removed from the well.   This  process



 also  enhances  the yield  potential  of the  monitoring  well, a  critical



 factor  when  constructing monitoring  wells  in   low-yielding  geologic



materials.




     More  importantly,  monitoring wells  must  be  developed to  provide



water free  of  suspended solids for sampling.  When  sampling  for  metal
                                   72

-------
ions and other  dissolved  inorganic  constituents,  water samples must be



filtered and preserved at  the  well  site at the  time  of sample collec-



tion.   Improperly  developed monitoring wells  will produce samples  con-



taining suspended sediments that will both bias  the  chemical  analysis of



the  collected  samples and cause frequent  clogging  of field  filtering




mechanisms (60).  The additional time  and  money spent  for well develop-



ment will expedite sample filtration and result  in samples  that are more




representative of water chemistry in the formation being monitored.



     The development  procedure used for monitoring wells are similar  to




those  used for  production wells.  The first step in development involves



the movement of water at  alternately high and low velocity into and out




of  the wellscreened gravel pack to  break down the mud  pack  on the well



bore and loosen fines  in the materials being monitored.   This step is



followed by pumping  to remove  these  materials from  the  well  and the,




 immediate  area outside the well screen.   This  procedure should be con-



 tinued until the  water  pumped from the well is visually free of sus-




 pended materials or sediments.




 Techniques for High Hydraulic Conductivity Wells



      Successful  development  methods   for  relatively  productive   wells




 include the use of a surge  block,   bailing, and surging'by  pumping.  A



 surge  block  is a  plunger device  that  fits  loosely  inside the well



 casing.  It is moved .forcibly up and down, causing water to  surge  in  and



 out  of the well  screen.   After  surging;  the well  must  be  pumped  to



 remove-the  fines  carried into the  well screen  and  casing.    The  use  of



 surge blocks   for monitoring  well  development  has  not been  widely used.



 However,  if the surge block  is sized to fit loosely  in  the monitoring
                                     73

-------
 well (0.64 cm (1/4 inch) total clearance) it can be  operated effectively



 by hand in relatively shallow wells,  less  than 15.17 m (50  feet)  deep.



 Care must be taken to avoid  damage to the  casing or screen  when surging



 a monitoring well.




      A bailer also may used to obtain the same  surging  effect created by



 a surge block.  The bailer   must  be  sufficiently heavy to  quickly fall



 through the water  forcing some  water to flow  out of the  well  into the



 surrounding formations.   The  upward  movement   of the  bailer will then



 pull the lessened fines into and remove them from the  well.  The use of



 bailers for  development  of monitoring wells is more  common than the use



 of surge blocks.   Bailing  is generally less effective than using surge



 block through the  potential for well  damage  is minimized.     ,   •




      Alternately pumping and  allowing a well  to equilibrate for  short



 intervals  is  another method for   developing monitoring wells.  .Pumping



 procedures  have    had  limited  application  in  very high  conductivity



 wells.   This  is  because  it is difficult to  draw-down these wells  suffi-



 ciently to create the high entrance velocities necessary for the removal



 of fines in the  aquifer and well bore.  This type of  development is more



 often attempted  by using air lift pumping mechanisms.



     When pumping  with  air,  the  effectiveness of the  procedure depends



 on the  geometry  of  the  device injecting air  into the well.   Figure 2.12



 illustrates a.simple device that diverts  air through the well screen  to



 loosen  the fines and forces air, water and  fines up  the well casing and



 out of  the well.   This  device is  particularly  effective for developing



monitoring wells in very productive geologic materials.



     Several  important  factors  should  be   considered  when  developing



monitoring wells with air.   First, the air  from  the  compressor must be
                                   74

-------
          SCHEMATIC DIAGRAM OF AN
     AIR DRIVEN WELL DEVELOPMENT DEVICE
Flattened nozzle with
   1/8" opening
                                  3/8" OD stainless or
                                     copper pipe
                                   Overall dimension
                                     less than 1-1/i"
         1/8" diameter hole (both sides)
             Figure 2.12
                     75

-------
filtered to  ensure that oil  from  the air compressor is not  introduced



into the well.  High  volume  carbon filters can be used successfully  to



filter  the  air  from  compressors.   Secondly,  in  highly  contaminated



ground-water situations air  development  procedures  may cause the  expo-



sure of  field personnel  to  hazardous materials.   Precautions  must  be



taken to  minimize   personnel exposure.    Finally,  air development may



perturb the  oxidation-reduction  potential of the formation of  interest



with effects on the   chemistry  of  initial  water samples.   Experience



shows that in  permeable sand and gravel situations, the effects do not



persist for more than a few weeks.





Techniques for Low Hydraulic Conductivity Wells



     Development  procedures  for  monitoring wells  in relatively unpro-



ductive  geologic   materials   is  somewhat  limited.    Due  to  the low



hydraulic conductivity of the materials, it is  difficult to surge  water



in  and  out  of  the well  casing.   Also,  when the well  is pumped, the



entrance velocity  of  water  can be too low to remove fines effectively



from the well bore and the gravel pack material  outside the well screen.



     In this type  of  geologic setting, clean  water should  be  circulated



down the well casing  out through the  screen and gravel pack,  and up the



open bore hole prior  to placement  of  the grout  or seal in the  annulus.



Relatively high water velocities  can be maintained and  the  mud cake from



the bore hole  wall will  be  broken down  effectively and removed.  Flow



rates should be  controlled to prevent floating the  gravel pack out  of



the bore hole.   Because of the relatively  low hydraulic conductivity  of



geologic materials outside the well,  a negligible amount of  water will



penetrate the formation being monitored.   However,  immediately following
                                   76

-------
this procedure, the well sealant should be  installed and the well  pumped



to remove  as  much of  the  water  used in  the  development  process  as




possible.





Hydraulic Performance of Monitoring Wells



     The  importance of  understanding the  hydraulics   of  the  geologic




materials at a site cannot  be over emphasized.  Collection of  accurate




water level  data from properly located and constructed wells  provides



information on the  directions,  horizontal and  vertical,  of ground water




flow (61).  The  success of a monitoring program also  depends on  knowl-



edge of  the rates  of  travel of  both the ground water  and solutes.   The



response of a monitoring well to pumping also must  be known to determine



the  proper  rate  and  length of  time  of pumping prior to collecting  a



water sample.  Finally, the required sampling frequency should be  deter-




mined based on the rate of ground-water travel, the mobility  and persis-



tence of the  chemical constituents  of interest, and  the goals  of  the



monitoring program.



     It  is recommended that "field"  hydraulic  conductivity test be con-



ducted  to avoid the  unresolved issues involved in  laboratory  testing.



Conductivity tests  should  be  performed on every well  in the  monitoring



system  to provide maximum understanding of  the hydraulics of  the site



being  monitored,  provide  information for  recommended  sampling  proce-



dures,  and to  determine appropriate sampling frequencies for  the wells.



     Traditionally, hydraulic conductivity testing has been conducted by



collecting  drill samples which were  then  taken to the  laboratory for



testing.  Several  techniques using laboratory permeameters are routinely



used.   Falling  head  or  constant head permeameter  tests on  recompacted
                                   77

-------
 samples  in fixed wall or triaxial test cells are among the most common.



 The  relative  applicability  of these  techniques is  dependent on  both



 operator   skill  and  methodology   since  calibration  standards  are  not



 available.   The major problem with laboratory test   procedures  is  that



 one  collects data on recompacted  geologic  samples  rather  than geologic



 materials  under field conditions.   Only  limited work has  been  done  to



 date  on  performing laboratory tests  on "undisturbed"  samples  to improve



 the field  applicability of laboratory hydraulic conductivity results.




 Water Level Measuring Techniques




     There are  three  common  water   level measurement  techniques  or



 devices  used  for  measuring  water levels  in monitoring  wells, steel



 tapes, electric  drop  line, and pressure   transducers.   General descrip-



 tions  of  their  use  and  their  relative  accuracy are  discussed in  the



 following sections.




 Steel Tapes




     The use of  relatively  narrow (o.64- to 0.95-cm  (1A- to 3/8-inch)



 wide)  steel  tapes  is  among  the  most  accurate and  straight  forward



 methods for making water level measurements.  Tapes  that   are graduated



 throughout their entire length in  feet, tenths  of a  foot,  and  hundredths



 of a  foot with   raised lettering and divisions are  preferable.   The



raised surface of the tape will permit the  observation  of  color  changes



when the chalk or other material is wetted.   The bottom few feet of the



tape is chalked and lowered into the  well  to the  anticipated water level



depth so that the chalked portion  of  the tape is  in  the  water.  The tape



is held at an even foot mark, making  sure  that  the tape  has been con-



tinuously lowered into the water and  not raised back to  the  foot marker.
                                   78

-------
The tape  is  then withdrawn and the  reading  from the wetted portion of




the tape subtracted from the  foot  reading held at the measuring point.




The resulting value is the  depth to water  from  the measuring point.




     Measurements taken  in this manner are  generally accurate  to the




nearest  1/100  of  a foot.    Three  readings  should  'be taken  for each



measurement to ensure that  reproducible results are obtained.





Electric Drop Lines



     Commercially purchased and home-made  drop  lines  are often  used for




measuring water  levels  in  monitoring  wells.  Two conductor electrical



wire is  'fitted with a probe  to hold the  two wires  apart and marked at



30.48- to 152.40-cm (1- to 5-foot) intervals   through  out  its  entire



length.  Drop  lines are  generally  powered  by flashlight  batteries and



equipped with  a  milliammeter.   The drop line is  lowered into the well



until  the  probe  contacts the water  closing the  circuit between  the two




wires  and the meter indicates a current flow.  The   drop line  is pulled



back and a ruler used to measure the distance between the nearest 30.48-



or 152.40-cm. (-1- or 5-foot) markers on the drop line.



     After repeated use the markings on drop  lines often  have a tendency



to become loose  or to slide along the wires.   Drop lines  may also become



kinked and don't hang straight in the well.  These among  other  potential



problems  can   limit the  accuracy of  drop  lines  to about 1/10 of  a  foot.



They are, however, very  convenient to use particularly in deep  wells and



don't  need to  be  be totally reeled out  of  the well  to  get multiple




readings.
                                    79

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 Pressure Transducers




      Pressure transducers have not  been  used  in monitoring wells until



 the last four to five years.   Their use does,  however, offer advantages



 over the steel tape  and  electric  drop  line.  Transducers  can be,lowered



 into a monitoring well  to a known  distance below the measuring point and



 by indicating the amount  of  pressure exerted on it, measures the height



 of  water  above  the  transducer.     This amount   of  "submergence"  is



 subtracted  from  the  depth   below  the  measuring  point  at  which  the



 transducer is located to  obtain the  depth to the water.  Transducers are



 particularly  useful for making water level measurements in a well during



 pump or slug  tests.   The  transducer  is  left  in the well  and transmits a



 continuous  record  of  water  level  data  to a strip  chart or  digital



 recording device  during the course of the test.  Permanent installations



 of   transducers  into  individual  wells  normally   cannot  be  justified



 because of their relatively high costs.




      The accuracy of  transducers depends  on  the  type  and  sensitivity of



 device  used.  Most transducers are rated  in terms  of  a percent  of their



 full  scale  capability.    For  example, a 0 to 5 psi transducer rated at



 0.01  percent will provide readings to the  nearest  0.30 cm  (0.01  foot).



 A  0  to 25 psi transducer rated at 0.01 percent  will  provide reading to



 the nearest 1.52 cm (0.05 foot).





Hydraulic Conductivity Testing Methods



Slug tests




     Slug or  bail tests  are  described  in detail  in  Freeze and  Cherry



 (62).  Two tests,  one suitable for  a point piezometer and  one suitable



for  a well  screened over  the  entire saturated thickness of an aquifer
                                   80

-------
are 'presented.  Both tests are initiated by introducing a sudden change



in water  level and  measuring the  resulting  response  of  the  well or



piezometer.   The  change  in  water level can  be  accomplished by intro-




ducing a  known  quantity of  water, slugging the well,  or  by removing a



known quantity of water with a bailer.  These methods are suitable for




relatively  low conductivity  settings  where  the  resulting  changes in



water levels  take  place slowly and  accurate  measurements  'can  be made.



However, for wells where  hazardous  contaminants are  suspected,  removing




water from the well may not be desirable.  In the  case of the slug test,



water of a different quality than that in the aquifer also  is introduced




into the system and must be removed prior to sampling the well.



     Prosser  (63)  described a method  of depressing the water  level by



pressurizing the well  casing and  then  rapidly releasing the  pressure to



allow the  water level  to recover.   This technique minimizes  the distur-



bance  of  the  well  and  has  the  least  potential for compromising  the



integrity of  water  quality samples.   This  method also can  be  used for



conducting tests  on wells with very high  hydraulic conductivities  when




pressure  transducers are  used for the water level measurements.



     The   analyses  of   slug  or  bail  test  data  has  been  described  by



Hvorslev  (64) and Cooper et  al.  (65).   The  Hvorslev method  is for  a



point  piezometer,  while  that  of  Cooper is for a confined aquifer.   In



most instances the method described by  Hvorslev  can be  used.   Hvorslev



analysis  assumes a homogeneous, isotropic,  infinite medium in which both



the fluid and soil  are incompressible.   The  rate  of  inflow to the




 piezometer (q) is  defined by equation  2.3:
                                    81

-------
                                   q(t)  =  IIR2 (dh/dt) = FK(H - h)          (Eq. 2.3)

               where R = radius of the well

                     F = shape factor determined by the dimensions of the piezometer

                     K = hydraulic conductivity

                     H 3 initial water level above a reference point (±0.01  ft)

                     h = water level above the reference point at time t (±0.01 ft)

               See  Figure    2.13a.    flvorslev  defines  the  basic  time lag,  To,   as

               equation 2.4:

                                            T0 = (JIR2/FK)                     (Eq.  2.4)

               By substituting  this  parameter into   equation 1 ,  the  solution to  the

               resulting ordinary  differential equation, with  the  initial  condition,

               h = H0 at  t = 0 is:
                           H - h
                           H - Hr
                                     -t/T,
               A plot of field recovery data, H  -  h /  H - Ho versus  t  on  a logarithmic

               scale results in  a  straight  line. Note  that for H - h / H - H0 = 0.37,

               ln(H - h / H  -  H0)  = -1,  and from equation 2.4, To = t. This  describes

               the basic time lag.

                    To interpret field data,  the data  are plotted as  shown on Figure

               2.13b.   The basic  time lag is graphically measured and K  is determined

               using equation 2.3.    For  a piezometer intake of length L  and radius R,

               with L/R  > 8,  Hvorslev has  evaluated  the shape  factor, F,   and  the

               resulting expression for K  is equation 2.5:

                                            K = r2ln(L/R)                    (Eq. 2.5)
                                                 2LTn
                                                  82
_

-------
HVORSLEV PIEZOMETER TEST, (a) GEOMETRY; (b) METHOD OF ANALYSIS

                           (from ref. 64)
           J_

           T
           dh
    H  h  HoV-
-t = co (and t<0)

       1\

•t+dt    £

•t       §
        u
        CO
        (E
•t=0   —L-
           -Datum


            (a)
                                   0.5 -
0.37
                                      0   2   4   6   8   10
           (b)
                           Figure 2.13
                                  83

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 Pumping Tests




      Pump  tests  on  monitoring wells  are often  difficult  to  perform.



 Relatively low pumping  rates,  100 to  1000  milliliters  per minute com-



 monly are required to produce  data suitable for analysis.  Problems of



 disposing of the water  pumped  and making accurate water level readings



 also must be addressed.   Constant rate pump tests for periods of two to



 four hours are  normally required.   Traditional analyses of  pump test



 data use equations derived by Theis  (66) and Jacob (67).  One of the



 basic assumptions made  in deriving those  equations is that all of water



 pumped from a well during the pumping test  comes from  the  aquifer and



 none comes from storage   within  the well.    This condition  is  seldom



 encountered  in monitoring  wells.  Therefore,  the methods presented by



 Papadopulos and  Cooper  (68),  which take  into  account  the water  removed



 from storage  in the well  casing, should be used.  This method as  applied



 to monitoring wells is described by Gibb  (11).   it should be noted that



 the  well construction procedures,  particularly "smearing" of the  well



 bore or  infiltration  of  drilling muds,  can significantly impact  hydrau-



 lic  conductivity calculations  (69).    Therefore,  well  development   is



 essential prior to hydraulic conductivity testing.




Analysis of Water Level Data




     In  settings where  slug tests or  pump tests can not  be  performed,



historical  water level   data   can  be  analyzed  using  the   procedures



outlined  by  Stallman (70).  Reasonable  estimates of  hydraulic  conduc-



tivity can be made by  selecting appropriate well arrays  and periods of



time when little or no recharge has occurred.   Successive selections of
                                   84

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various well arrays  will  permit the determination of hydraulic conduc-




tivity values for most wells in a monitoring program.



     In  all  of  the   above  described procedures  there  are significant




sources of error.  Water levels  should be measured to the  nearest  ±0.30




 centimeters (0.01 foot),flow rates for pump tests to ±5 mL per minute,



and time to the nearest 2 seconds.  Hydraulic conductivity  values deter-



mined by the various methods should not be considered to be more precise



than  ±20 percent.   To minimize the  potential  error  and  quantify  the



degree of variance,  3 to 5 slug or pressure tests should be conducted on



each well.  The time  and expense required to perform multiple  pump  tests




do not normally warrant the effort.



      In  addition to  the  above sources of  measurement  and interpretive




errors,  wells  that  have not been properly constructed or developed will



not  provide accurate data for determining hydraulic conductivity values




of  the materials  in  which  the well  is finished.  Care also must be exer-



 cised when  performing these tests to  insure that pumping or injection of




water by nearby wells does not  affect  the results of these tests.





Well Maintenance  Procedures



      A plan for well maintenance and performance reevaluation should be




 prepared to  insure  that   the sampling point  remains  reliable.    As a



 minimum, high  and  low water level  data  periods  for  the site should be



 examined once every  two years  to insure  that the well locations  (hori-



 zontally and vertically)  are still acceptable.  It is  also particularly



 important  to  note  that the  exposure of  the screened  interval,  to  the



 atmosphere due to low water levels can compromise the  integrity of water




 samples.   Hydraulic conductivity tests should  be  performed  once every
                                     85

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 five  years or  whenever significant  amounts  (7.62-15.24  cm  (0.25-0.50

 feet))  of  sediment have accumulated in the well.   Deficiencies  in well

 locations,  delivery of decreases  in  hydraulic conductivity,  or  turbid

 samples  should  be corrected by well redevelopment,  the  installation  of

 new wells or the rehabilitation of existing wells.

      The operation of  wells  in the vicinity of the  site under investi-

 gation also may affect' changes in the hydrologic setting  and resulting

 flow paths.  Biannual  evaluation of the high and low water level  condi-

 tions at a site under  evaluation is recommended to ensure  that the well

 locations and  depths  are still  appropriate.   Piezometric surface maps

 for horizontal flow direction determination and vertical cross sections

 of equipotential lines  for  vertical flow determination should be plotted

 and reviewed.    The example below  illustrates  how  site  operation often

 causes  failure of the original  monitoring well design.


 Example 2.2.   Effects of waste  disposal activities on site  flow regime--

      Figure  2.14 showed a relatively flat site with a slight water table
 gradient  prior to the  placement of a waste impoundment.   Background and
 down  gradient wells were  constructed  to  determine  the  hydrologic and
 chemical  nature  of the  site prior to waste  disposal.  Water level data
 from  the nested monitoring wells were  used  to  determine  the horizontal
 and vertical components  of ground-water  flow.   In   the  pre-disposal
 situation water  passing the upgradient shallow well BG-S was expected to
 flow  past the deep downgradient well DG-D2.

     After the installation of  the disposal  system  a ground-water  mound
 was  created  beneath the impoundment.   The  increased head  beneath  the
 impoundment  also resulted in the  reversal  of  ground-water flow in  its
 immediate vicinity.  Background wells BG-D and BG-S  are  both now  likely
 to  receive  leachate from  the  source.   Similarly,  the   increased  head
 beneath  the  impoundment increases  the  vertical component  of  flow  and
 causes  the  downgradient flow of  ground water  to  move deeper  into  the
regional  flow system.  This shift in flow patterns  indicates the need to
 construct a deeper well at the site DG-D2 and DG-S2.

     This type of  analysis  should be performed  for  high and low  water
level periods once  every two or three years  to  insure that  the designed
monitoring system  is still applicable to possible changes in the hydro-
logic system.

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       In  addition  to  determining  that  the  monitoring wells  are still

  properly located,  documentation must be  presented  to ensure  that  the

  wells are  physically  intact and  capable  of yielding water  samples as

  designed.  Chemical encrustation or  bacterial growths on the well screen

  may result  in decreased well performance and possible alteration of  the

  chemical  quality of pumped samples.  Well depth measurements . should be

  reported  on  an  annual  basis  to  document that  the  well  is  still

  physically  intact  and  not filling with sediment.  Turbid  water samples

  are  an  indication that the well intake or screen is  not functioning as

  designed  and is likely to accumulate sediments.

      Another  recommended  procedure  for  documenting  the  integrity   of

 monitoring wells is to require  that  slug or  pump tests be conducted  on

 each well once  every five years.   Comparisons  of these test data with

 thatcollected originally provides  documentation on  the  presence   and

 degree of well  deterioration.   This  data can then be used to determine

 if and when new wells  or well  rehabilitation  is needed.   The example

 below illustrates common problems  often encountered as the  age of moni-

 toring wells increase.


 Example  2.3.  Well  deterioration and  plugging—


 ino*.  ti *«ir 2~inch diameter  PVC monitoring well was
 iS   i?   in September  1979  within  250  feet of  a  petrochemical  plan?
 waste disposal impoupndment site.   Upon completion,  the well  was tested
 and  found  to have a hydraulic conductivity of 5.2 x  1 
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     The problems associated  with this well are  two-fold.   During the
first two  years,  sediment  had accumulated due  to improper  development
procedures.  The cessation of sediment accumulation could have been due
to the ultimate development of the well from  repeated  pumping during the
sampling of the well.  It  also could  have  been  due to the slow plugging
of the well screen or aquifer reflected by the  drop in hydraulic  conduc-
tivity   Due  to the nature  of  the possible leachate from the disposal
site being monitored, the life of the well could be threatened by attack
of  the  well casing materials.   Careful  monitoring  of the well  perfor-
mance and  chemistry  is  recommended.   The well  may need to  be replaced
with a  new  well  constructed  of more suitable materials  for  this  type  of
environment.

Well Purging Strategies

     The  number of  well  volumes  to  be  pumped from  a monitoring  well

prior  to  the  collection  of  a  water sample must  be  tailored   to  the

hydraulic  properties of  the  geologic materials  being monitored,  the well

construction  parameters,  the desired  pumping  rate,   and  the  sampling

methodology to  be  employed.   There  is  no   one single number  of well

 volumes to be pumped that is best or fits all  situations.   The  goal  in

 establishing  a well  purging strategy is to obtain water  from  the geo-

 logic materials being monitored while minimizing the disturbance of  the

 regional flow system and the collected sample.   To accomplish this goal

 a basic understanding of  well hydraulics  and  the effects  of pumping on

 the quality of  water samples is essential.   Water that has remained in

 the well  casing for extended periods  of  time   (i.e.  more than about  two

 hours) has the opportunity  to exchange gases with the  atmosphere and to

 interact with  the well  casing material.   The  chemistry of  water stored

 in  the well  casing  is unrepresentative of that in  the aquifer and it

 should not be  collected for analysis.  Purge  volumes  and  pumping rates

 should be  evaluated on  a  case by case basis.
                                     89

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             Pumping Rates
                  The rate at which wells are p.urged of stagnant water should be kept
             to  a minimum.   Purging  rates  should be maintained  below the rates  at
             which  well development  was  performed since   well  damage can  result.
             High purging rates  can  also cause additional development  to  occur with
             resulting increased turbidity of water samples.   Well hydraulic perform-
             ance evaluation is  essential  to  the  determination  of  effective  well
             purching rates and volume requirements.
             Evaluation of Purging Requirements
                  When a well  is pumped a  certain  amount  of  drawdown is  created  in
             the well and the surrounding aquifer system to  induce flow of water  to
             the well.   Traditional well analysis techniques described by  Theis  (66)
             and Jacob  (67)  can be used to predict the amount of drawdown experienced
             by wells under water table and  piezometer conditions.  The reader should
             recall  from above  that  the  basic assumptions made  in  deriving these
             relationships  require that an  insignificant amount  of the water pumped
             comes from  the  well  bore.  This condition  is  seldom  experienced in the
             case  of small diameter monitoring wells, particularly for wells finished
             in low hydraulic conductivity geologic settings.   Popadopulos and Cooper
             (68)  presented  an equation that  describes  the discharge from a  pumped
            well  which  takes into account  the  volume  of water removed  from  casing
            storage.
                 Well test  data  for  six monitoring wells  studied, in  Illinois  have
            been analyzed using these equations (11).   At all  of the sites  studied,,
            the nonpumping  water  levels  were  significantly  above the  top of  the
            aquifers tapped, suggesting  artesian  conditions.    In  this   case,  a
                                               90
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storage coefficient of 0.0001 was  used in the analysis of the  drawdown

data.  The storage coefficient values selected should have little  effect

on the predicted drawdowns for most aquifer systems using  this equation.

     Using the Popadopulos and Cooper equations (68), the  percentages of

aquifer water  pumped  for a two inch  diameter well  pumping at a rate of

500  mL/min  for a range  of transmissivities were  calculated,  see  Figure

2.15.   These calculations  give  an  indication of  the sources  of water at

various  times for a well that  is  being pumped with the  pump intake at

the  top of  the well  screen.  Different percentages would result  if the

pumping rate,  well  diameter,  or aquifer  properties were different. These

types  of calculations should be used as guidelines for the selection of

the  appropriate pumping rate and  numbers of well  volumes to be pumped

 prior   to  sample  collection.   However,  they  are only  guidelines and

 should be  verified by  the  measurement of  indicator  parameters  at the

 well  head  during  pumping collection.   Two  examples of  pumping  rate

 selection and appropriate well  purging volumes are given  below.


 Example 2.H.  Well purging strategy based on hydraulic conductivity
 data—
      Given:
           J48-foot deep, 2-inch diameter well
           2-foot long screen
           3-foot thick aquifer
           static water level about 15_feet below land surface
           hydraulic conductivity = 10~2 cm/sec
       Assumptions:
            A desired purge rate  of  500 mL/min  and  sampling rate of 100
            mL/min will  be  used.
       Calculations:
            One well volume = (48 ft  -  15  ft)  x  613 mL/ft  (2-inch diame'
                                well)
                            =20.2 liters
                                     91

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                                = 500mL/min
                          DIAMETER = 5.08 cm
                 10     15     20
                   TIME, minutes
Figure 2.15.  Percentage of aquifer water versus
      time for different transmissitivites
                       92

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         Aquifer Transmissivity
= hydraulic   conductivity   x   aquifer
    thickness
= 10"^ m/sec x 1  meter
= 10"1* m2/sec or 8.64 m2/day
          From Figure 2.15

              at  5 minutes   -95$ aquifer water and
                             (5 min x 0.5 L/min)/20.2 L
                             0.12 well  volumes
              at  10 minutes  ~t005& aquifer water and
                             (10 min x  0.5 L/min)/20.2 L
                             =0.24 well  volumes

     It therefore  appears that a high  percentage of aquifer water  can  be
obtained  within  a relatively short  time  of  pumping.    The  indicator
parameters  should be  monitored  and  the  pumping rate  slowed  to the
desired 100 mL/min for sampling as soon as  they  have stabilized.  The
indicator parameters  should  be monitored at very  close intervals,  every
1 or 2 minutes from the time pumping begins.


Example 2.5.  Well purging strategy based on hydraulic conductivity
data—
     Given:
          48-foot deep, 2-inch diameter well
          2-foot long screen
          3-foot thick aquifer
          static water level about 15_feet below land surface
          hydraulic conductivity = 10~4 cm/sec
      Assumptions:
           A desired purge rate  of  500 mL/min and  sampling rate of 100
           mL/min will  be  used.
      Calculations:
           One well volume = (48 ft  -  15 ft) x  613 mL/ft  (2-inch diameter
                               well)
                           = 20.2 liters

           Aquifer Transmissivity =  hydraulic   conductivity   x  aquifer
                                      thickness
                                  =  10~6 m/sec  x  1 meter
                                  =  10~6 m2/sec or 0.0864 m2/day
                                     93

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            From  Figure  2.15

                 at  5 minutes   -20% aquifer water and
                               (5 min x 0.5 L/min)/20.2 L
                               -0.12 well volumes
                 at  10 minutes  ~30% aquifer water and
                               (30 min x 0.5 L/min)/20.2 L
                               -0.72 well volumes

      Based on these results,  it appears that it may be more desirable to
 pump this well down to the top  of  the screen and allow it  to  recover
 Dewatering the  screen  and the gravel  pack should  be  avoided  to  minimize
 aeration  effects on water chemistry.   The samples  can then be collected
 at the  desired  100 mL/min while the  well  is recovering.  Calculations
 using the  equations developed by Papadopulos and Cooper suggest  that  the
 well should recover at a rate of about  250  mL/min when the  water  level
 is near the top of the screen.   Therefore,  the  samples can be collected
 within  five  minutes  after  dewatering pumping  stops  and  can  continue
 until the  desired volume of  sample  is  collected.

      If the well was not  capable of recovering at a  rate  in excess of
 100 mL/min,  the sample would have  to be collected  in small aliquots
 The amount of water that could recover in two hours should be collected
 and another recovery  period  would be required to collect the  next sample
 segment.   The  recovered  water should not be allowed  to remain in the
 well  casing for more than about  two hours  prior to collection or it is
 likely  to be  chemically altered for several  parameters.

      The selection of  purging rates  and volumes of  water  to be pumped

 prior to  sample collection  can also  be  influenced  by the  anticipated

 water  quality.   In hazardous  environments  where  purged water  must  be

 contained  and disposed  of in  a permitted facility, it  is  desirable  to

 minimize the  amount of  purged  water.   This  can be accomplished by pump-

 ing the wells at very  low  pumping rates (100 mL/min) to  minimize  the

 drawdown in the  well and maximize the percent aquifer  water  delivered  to

 the surface in the  shortest  period of time.    Pumping at low  rates,  in

 affect,   isolates the  column  of  stagnant water  in the  well bore and

negates  the need for its removal.   This approach is only valid in  cases

where the pump intake  is placed at the  top of, or.in,  the well screen.

     In   summary, well  purging  strategies  should  be  established   by

1)  determining  the  hydraulic  performance  of  the well; 2)  calculating
                                   94

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t-easonable  purging  requirements, pumping  rates,  and  volumes based  on
hydraulic  conductivity data,  well  construction  data,  site  hydrologic
conditions, and anticipated water quality;  3) measuring the well  purging
parameters  to  verify chemical  "equilibrated"  conditions;  and 4)  docu-
menting  the entire  effort  (actual  pumping  rate,  volumes pumped,  and
purging  parameter measurements  before and after sample collection).

SAMPLING MECHANISMS AND MATERIALS
      The selection  of appropriate sampling mechanisms and materials are
vital to the success  of any  ground-water investigation.  A situation may
be very thoroughly evaluated  as  to  the hydrogeologic conditions, opti-
mized sampling  frequency and  analyte  selection.   Also,  the sampling
 points may be  constructed and evaluated properly.  Nonetheless,  if poor
 sampling mechanisms  and materials are incorporated  into the program, all
 the preceding  effort  may  be  futile.  Minimally disturbed samples must be
 carefully collected and analyzed if the program is to meet its informa-
 tion  needs.   In many cases,  the results  of  preliminary  investigations
 can  be  reinterpreted, even  if inappropriate choices of sampling  mecha-
 nisms or materials have  been  used prior to  the  execution of  a sampling
 experiment.   These experiments should  include simultaneous sample  col-
 lection by both the  previous  mechanism and  sampling  components,  as  well
 as those which  are more  appropriate for the  current  situation based on
 the  available data.   For example, an  initial set  of monitoring  results
 collected  with a  conventional  bailer may  show  a  trace  of  volatile
 organic contaminants.   In order to substantiate these observations  and
 improve the reliability  of  the results,  a sampling experiment should be
 run, including both  bailed and bladder pumped samples on at least two
                                     95

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  successive  sampling dates.  This  approach will  permit  the objective



  evaluation of the effect  of  sampling procedures on  the  quality of the



  results and hopefully will  put an end  to  the generation of poor data.



  Tradition is a  very weak basis for  the selection or  continued  use of



  inappropriate mechanisms  or materials.




  Sampling  Mechanisms




      Sampling mechanisms  for  the collection of ground-water samples are



  among  the most  error prone  elements of  monitoring programs.  Several



  useful  sources have  reviewed  the range of  available  sampler designs and



  should  be consulted for specific information (3,11,13,52,71,72).   Unfor-



  tunately,  the  documentation of  field sampling performance for many of



  the available devices is  lacking.   Many  of the sampling  designs may be




 expected to  provide  adequate  performance for conservative chemical  con-



 stituents which are  not   (or   minimally)  affected   by  aeration,   gas-



 exchange and degassing.  Among these  constituents are Na"1",  K+ and Cl~.



 The chemical constituents which can provide the most useful  information



 to the investigation frequently  are effected by the  improper choice of



 sampling mechanisms.   Evaluations of  sampling  performance based  on the



 recovery of  conservative,  unreactive  chemical  constituents  are  simply



 not reliable  for  planning  effective monitoring  efforts.




     The introduction of  bias  into ground-water data sets  by sampling



 mechanisms  has been investigated by several groups (13,53).   in  a con-



 trolled  laboratory  evaluation  (53),  results  disclosed that sampling for



 dissolved  gases or  volatile organic compounds  is prone  to severe nega-



tive bias of the same order as analytical  error.  Further,  the precision



which may  be  achieved in  these cases is limited by both operator  skill
                                   96

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ana sampler design.   The  magnitude of these errors  corresponded to  the
extent to  which control  over  conditions during  sample  transfer  steps
(i.e. flow rate, atmospheric exposure, turbulence)  could  be  maintained.
Positive displacement bladder  pumps  were found to be the most  reliable
sampling mechanism evaluated since they  are simple  in design and opera-
tion and operational variables are easily controlled.
     Similarly, Korte  and Kearl  (73) recommended positive  displacement
bladder pumps over bailers, suction-lift and air-lift devices due to the
bladder pumps'  range  of utility,  minimal disturbance of  the  samples and
overall  simplicity of operation.   They  also  noted that bladder  pumps
permit efficient in-line  filtration of samples in the field.
     Modifications  of selected sample  collection mechanisms are  being
developed  to improve the reliability and applicability  of   ground-water
chemical  data.   Armstrong and  McLaren  (7*0  have  refined  pump/packer
arrangements  to optimize  the  isolation  of  the sample  intake as well as
sample  recovery.   Pankow et al.  (40) have investigated the application
of in situ sample  collection techniques  for organic  compounds which have
the advantage of minimizing sample exposure to either the atmosphere or
foreign materials.   The  routine  application  of these  and other refine-
ments for  ground-water sampling efforts  (75) must await further develop-
 ment .
      Work to  date has established  that there is  a great  need for the
 field evaluation of sampling  mechanisms.  This work has  also identified
 the capabilities which a  reliable sampling mechanism should  provide  .
      Important  characteristics  of  ground-water  sampling devices  which
 should be considered are:
                                    97

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      1.  The devices  should  be  simple  to  operate   in  order  to



             minimize the possibility of operator error.



      2.  The device  should  be  rugged,  portable,  cleanable  and



             repairable in the field.




      3-  The device should have good flow controllability to permit



             low  flow rates  (<100  mL/min)  for  sampling  volatile



             chemical constituents,  as well  as high flow rates  (>1




             L/min)  for   large-volume  samples  and  purging  stored



             water from monitoring wells.




      4.   The mechanism should  minimize  the  physical  and  chemical




             disturbance   of  ground-water  solution  composition  in



             order  to avoid   bias   or   imprecision in analytical



             results.




      The  scientific literature is somewhat inconsistent in  descriptions



 of  the types of  samplers  and their primary mechanisms of  operation.  In



 this  regard, gas-lift mechanisms are exemplified by down-hole dual tube



 arrangements,  which employ violent  gas/water  mixing to force  water  up



 and out of the well bore  (or large diameter tube).  Gas lift devices are



 proven  to be  biased  sampling mechanisms  for  a range  of  chemical con-



 stituents.    They are  not recommended  for  any  type  of  ground-water



 investigation.   Gas-drive devices, on the other hand, rely on controlled



 displacement  of  water from the sampler body  by either controlled  gas



 pressure  applied across  an interface or  by  gas pressure on a membrane



which permits for no gas  contact with the sample.




     Many sampling devices are designed for  either  deployment  in  a well



bore  or  as  devices  which are  buried at  discrete depths,  gravel/sand
                                   98

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packed and  sealed from other  formations analogous  to  a. properly  com-



pleted screened interval in conventional wells.   There are advantages  to



the  use  of dedicated  samplers,  particularly   for  complex  monitoring




situations  which  demand large arrays of  sampling points.  The  corres-



ponding disadvantages include difficulties in assessing proper placement



or malfunction.   The collection of hydrologic data  is  severely  limited




by most  of  these  devices.  The  choice  of a sampler  design,  appropriate




for the  situation of  interest,  should be made carefully after a  compre-




hensive review of the scientific literature.





Recommendations for Selecting Sampling Mechanisms



     It  should be recognized that the purchase of a suitable sampler for




most  ground-water investigations is  usually a very small portion of the



overall  program cost.   It is further   obvious  that the  choice of the



right  sampler  will  determine the usefulness  of the chemical data.   A




sensible approach is  to make the choice of  a  sampler on  the basis of the



most    troublesome  parameters  which may be of interest.   Typically,



samples  for dissolved gases and volatile organic compounds are the most




difficult to collect  and  handle..



      Negative  bias  (loss  of constituent)  is  the most common reason for



 poor sampling performance  for  gas-sensitive  or  volatile compounds.  In



 general, sampling  precision  may be  poorer by  a factor of  two  or more



 than that  involved in analytical methodologies alone.   Sampling bias



 problems may  be  far  worse  under  field  conditions,   particularly  for



 suction  mechanisms  and  those   devices  which involve   careful  operator



 attention  or  control (e.g. bailers  and gas drive devices).   Positive



 displacement bladder pumps meet all  of  'the important characteristics  for
                                     99

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 sampling mechanisms noted above.   These pumps  have  been found to be very




 reliable, efficient sampling mechanisms which exhibit excellent overall



 performance in all reported evaluations to  date.




      Table  2.4   contains   general   recommendations   for  ground-water



 sampling mechanisms.  It  should  be  noted that it is the responsibility



 of the  monitoring program  director  to  build in  sampling performance



 checks   into  the  QA/QC   program  to  verify actual  efficiency for  the



 chemical constituents  of  interest.





 Sampling Materials




      There exists  a wide range of  biological,  chemical  and  hydrologic



 conditions which may be encountered  in ground-water  sampling  programs.



 Even  if  personnel  safety is assured,  ground-water  sampling  activities



 must  be approached cautiously.    There   are many chemical  and  physical



 unknowns  which must be accounted for,  if the monitoring data  is  to  be



 truly useful.   Sampling  mechanisms  are only  an   element of  sampling



 protocols,  the materials  which  contact  the  samples  must  be  chosen  care-



 fully as well.





 Subsurface Conditions and Materials'  Effects




     The  "Guide  to the  Selection  of  Materials  for  Monitoring Well



 Construction and  Ground-Water Sampling"  (52) and the  thorough  treatment



 of sources of sampling bias  by  Gillham,  et  al. (13)  provide very useful



recommendations  for materials'  selection  and  error  minimization for



 ground-water  investigations.    Both   of .these  publications review the



 potential obstacles to materials'  related error control.




     Well casing materials, well  construction  and completion procedures



and sample  handling precautions all  enter into the ultimate quality of
                                  100

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101

-------
 ground-water  data.    The  principal  processes  by which  materials  can

 effect chemical data are:

           chemical attack:   corrosion/deterioration
           microbial colonization,  attack
           sorption effects:   adsorption/absorption
           leaching effects:   matrix/sorbed  component release

      These processes  may lead  to the  observation  of false  trends in

 analyte concentrations,  highly variable water chemistry and the identi-

 fication of artefacts resultant from surface release or sorptive inter-

 actions.    As  with the  errors  which sampling  mechanisms  can introduce

 into the chemical data,'materials' related errors can be quite signifi-

 cant and difficult to predict   (23,52).   Appropriate materials'  choice

 for  each application   must be made on the basis of long-term durability,

 cleanability,  and the minimization of  the secondary effects of sorption

 or leaching.   Structural integrity is,  therefore, the primary criterion

 for  making reliable  material  choices.    The materials must  neither be

 attacked  nor degraded during the course of the monitoring program.   Then

 the  severity of the   effects of  loss  or contamination resulting  from

 sorption  or leaching  of  the components  of  the sampling train must be

 considered.  In general,  it is wise to base materials' choices on the

most error  prone constituents of interest.

     To evaluate the  magnitude  of  materials'  effects,  it is instructive

 to consider the relative  surface  area  contact  which   aquifer solids,

well casing and sampling tubing will have with the water samples.  Table

2.5 contains a  comparison of  these materials  and  their relative surface

area contact under monitoring well sampling  conditions.  Assuming rela-

tively high linear  ground-water velocity (50 cm«d~1)  and pumping rates

of -100  mL/min,  it  follows  that  aquifer   solids   are  a  potentially
                                  102

-------








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 greater  source  of  material  surface  effects  on water  quality than either



 well casing or  sampling  tubing.   Since  we  cannot  exert  control  over the



 native geology,  the  effects of gravel  packs  and  grouting materials may



 be  expected to  be more  important  than  those due  to well  casing  or



 sampling train materials.  Relative to conditions  in  the geologic forma-



 tion of  interest, sampling  tubing is  in much  more intimate  contact  with



 the water sample collected  after  proper purging than would be  the  well



 casing.  One should not  assume that materials' effects will cancel  out



 in comparisons of  upgradient  or   downgradient monitoring  well  data.



 Materials'  related bias  will be present in  all  samples though  perhaps



 not to the  same extent.   The   effects of  materials  in comparisons of



 sample  results are most  pronounced  under  differing chemical conditions



 where  some materials  may be attacked  or  leached to  varying  degrees.



 Purging may minimize the  effects of  potential  well  casing interferences,



 however this is  difficult to substantiate under field conditions.



     Sampling  train components, particularly  sampling tubing,   are  the



 most critical  selections  which  must  be made  to avoid  materials'  related



 error.  A recent study has  demonstrated that  serious  bias  of  dissolved



 organic compound results  occurs quite  rapidly (within 5-10  minutes)  due



 to  absorption  on flexible tubing   exposures  (76).   In  this study  all



 commonly  used  tubing materials  (Teflon(R),  polypropylene, polyethylene,



 etc.) sorbed organic compounds  to  some extent.  The sorptive error  was



most serious for polyvinyl chloride and silicone rubber tubing.




Recommendations for Selecting Sampling Materials




     The primary criteria for the selection of  materials for all  compo-



nents of the sampling point  and sample collection  train should be mech-
                                  104

-------
anical performance and chemical  inertness.   Since  the  actual subsurface

geologic  and  chemical  conditions which  may  be  encountered  are  very

difficult to  predict,  the choice of  materials must be  made carefully.

It is recommended  that  sampling  components be chosen  of  the most inert

and error-free  materials  available.    The  costs  of analysis  (or  repeat

analyses) and the labor involved in sample collection are generally much
                                                          u.
higher than the cost of appropriate materials for sampling ground water.

     Sampling materials may be categorized as  either  rigid or flexible.

Rigid  components  include well casing,  pump bodies and  fittings, while

tubing,   bladders   and   gaskets   are  generally   flexible   materials.

Tables 2.6 and  2.7 detail general recommendations for rigid and flexible

materials, respectively.  Teflon(R) components are superior to all other

materials' combinations for ground-water  sampling.  The  mechanical per-

formance  of  this  material  may require that it be used in combination

with stainless  steel.   The  available literature  on materials evaluation

for sampling ground water substantiates  these  recommendations   (23,52,


72,76).



SAMPLE COLLECTION  PROTOCOL

     A  well  conceived sampling  protocol  consists  of  a written descrip-

tion  of  the   actual  sampling  and  analytical  procedures  involved  in

obtaining representative  ground-water data.   The  protocol must  reflect

special  attention to the need to collect  high  quality  hydrologic data

 (e.g.  water  level,   hydraulic  conductivity,  etc.) and to  record any

unusual  occurrences or  departures from written procedures.   The value of

water  quality measurements  has been  emphasized repeatedly in the-  litera-

ture.    However,   it  is  very  difficult  to fully  interpret  the water
                                   105

-------
   Table 2.6.  Recommendations for Rigid Materials in Sampling Applications
                     •(In decreasing order of preference)
       Material
Teflon(R)
(flush threaded)
                                               Recommendations

                            Recommended for most monitoring situations  with
                            detailed organic analytical needs,  particularly
                            for   aggressive,    organic   leachate   impacted
                            hydrogeologic  conditions.  Virtually  an  ideal
                            material   for    corrosive   situations   where
                            inorganic contaminants are of interest.

                            Recommended for most monitoring situations  with
                            detailed organic analytical needs,  particularly
                            for   aggressive,    organic   leachate  impacted
                            hydrogeologic conditions.

                            May  be  prone  to  slow  pitting  corrosion  in
                            contact with acidic high total dissolved  solids
                            aqueous  solutions.   Corrosion products limited
                            mainly to Fe and possibly Cr and Ni.

                            Recommended for limited  monitoring   situations
                            where inorganic contaminants are of interest and
                            it  is  known  that aggressive  organic leachate
                            mixtures  will  not  be   contacted. '   Cemented
                            installations   have   caused  documented inter-
                            ferences.   The  potential  for  interaction and
                            interferences from PVC well  casing  in  contact
                            with  aggressive  aqueous  organic  mixtures  is
                            difficult  to  predict.   PVC is not recommended
                            for detailed organic analytical schemes.

                            Recommended     for     monitoring     inorganic
                            contaminants  in  corrosive,  acidic   inorganic
                            situations.   May release Sn or Sb compounds from ,
                            the original heat  stabilizers in the formulation
                            after long exposures.
(R) Trademark of DuPont,  Inc.

  * National Sanitation  Foundation  approved  materials carry  the  NSF  logo
    indicative of the product's certification of meeting  industry  standards
    for performance and formulation purity.
Stainless Steel 316
(flush threaded)
Stainless Steel 304
(flush threaded)
PVC
(flush threaded)
other noncemented
connections, only NSF*
approved materials for
well casing or potable
water applications
                                     106

-------
       Material
Low-Carbon Steel

Galvanized Steel

Carbon Steel
Table 2.6.  (Continued)
                    Recommendations

May   be   superior   to  PVC   for   exposures    to
aggressive    aqueous   organic  mixtures.  These
materials must  be very  carefully  cleaned  to
remove   oily   manufacturing  residues.  Corrosion
is   likely  in high   dissolved   solids  acidic
environments,  particularly  when  sulfides  are
present.  Products  of corrosion are mainly Fe and
Mn,   except   for  galvanized  steel  which  may
release   Zn  and  Cd.   Weathered  steel  surfaces
present  very  active adsorption  sites for trace
organic  and inorganic  chemical species.
                                     107

-------
  Table 2.7.  Recomendations for Flexible Materials in Sampling Applications
                      (In decreasing, order of preference)
        Materials
Teflon(R)
Polypropylene

Polyethylene (linear)



PVC (flexible)
Silicone
(medical grade only)

Neoprene
                  Recommendations
Recommended    for    most    monitoring    work,
particularly  for  detailed  organic  analytical
schemes.  The material least likely to introduce
significant  sampling  bias or  imprecision.   The
easiest  material to  clean  in order  to  prevent
cross-contamination.

Strongly   recommended    for   corrosive   high
dissolved  solids  solutions.    Less  likely  to
introduce  significant   bias   into   analytical
results than polymer formulations (PVC) or other
flexible   materials   with   the  exception   of
Teflon(R).

Not recommended  for  detailed organic analytical
schemes. Plasticizers and stabilizers  make up a
sizable percentage of  the material  by weight as
long  as   it  remains  flexible.     Documented
interferences are  likely .with  several priority
pollutant classes.

Flexible  elastomeric  materials   for  gaskets,
0-rings,   bladder   and   tubing   applications.
Performance   expected   to   be  a  function of
exposure  type   and  the   order  of   chemical
resistance as  shown.  Recommended  only  when  a
more suitable material is not  available  for  the
specific use. Actual  controlled  exposure trials
may be  useful  in  assessing  the potential  for
analytical bias.
(R) Trademark of DuPont, Inc.
                                     108

-------
chemistry  or  the  actual extent  of contamination  unless high  quality



hydrologic data is  collected  and interpreted properly.   Indeed,  it  may



be advisable to  collect  the hydrologic data at more  frequent  intervals




and at finer spatial scale than that used for the chemical data.



     The  principal  steps  in  the  sampling  protocol  are  listed  in



Figure 2.16.   The goal for each step   is also provided  with  a  general



recommendation for  achieving  it.   These general elements  are  common to



all ground-water sampling efforts.  It should be the responsibility of a



designated member  of  the sampling staff to  record  progress  through the




protocol at each sampling point.



     To  insure maximum  utility of  the  sampling  effort  and  resulting



data,  documentation of the sampling protocol as performed in  the field



is  essential.   In  addition to  noting   the obvious  information (i.e.,




persons  conducting  the sampling, equipment used, weather  conditions, and



documentation  of adherence  to the  protocol and  unusual observations)



three  basic  elements  of   the  sampling  protocol   should be  recorded:



1)  water level measurements  made  prior to  sampling,  2)  the volume and



rate at  which  water is removed from the well prior to sample collection



 (well  purging),  and  3)  the  actual sample collection including measure-



ment  of well-purging  parameters,  sample preservation,  sample handling




and chain  of custody.





Water  Level Measurement



     Prior to the  purging  of  a well  or  sample  collection,   it  is



 extremely  important to measure and record the water level in the  well  to



 be  sampled.   Water level measurements are needed to  estimate the amount



 of  water  to  be  pumped  from  the well  prior to sample  collection.    In
                                   109

-------
        Step
           Goal
                                   Recommendations
 Hydrologic
 Measurements

 Well Purging
Sample Collection
Filtration/
Preservation
Field Determinations
Field Blanks/
Standards
Sampling Storage/
Transport
 Establish nonpumping water
 level.

 Removal  or isolation of
 stagnant H20  which
 would otherwise  bias
 representative sample.
 Collection of  samples
 at  land  surface or  in
 well-bore  with minimal
 disturbance of sample
 chemistry.

 Filtration permits
 determination  of soluble
 constituents and is a
 form of  preservation.  It
 should be  done in the
 field as soon  as possible
 after collection.
Field analyses of samples
will effectively avoid
bias in determinations of
parameters/constituents
which do not store well:
e.g., gases, alkalinity,
pH.

These blanks and standards
will permit the correction
of analytical results for
changes which may occur
after sample collection:
preservation, storage, and
transport.
Refrigeration and protec-
tion of samples should
minimize the chemical
alteration of samples
prior to analysis.
 Measure the water  level  to
 ±0.3 cm (±0.01  ft).

 Pump water  until well
 purging parameters (e.g.,
 pH,  T,  JT1,  Eh) stabilize
 to ±1055 over at least  two
 successive  well volumes
 pumped.

 Pumping rates should be
 limited to  -100 mL/min
 for  volatile organics  and
 gas-sensitive parameters.
 Filter;  Trace metals,
 inorganic anions/cations,
 alkalinity.
 Do not Filter;  TOC, TOX,
 volatile organic compound
 samples; other organic
 compound samples only
 when required.

 Samples for determina-
 tions of gases, alkalinity
 and pH should be analyzed
 in the field if at all
 at all possible.
At least one blank and
one standard for each
sensitive parameter
should be made up in the
field on each day of
sampling.  Spiked samples
are also recommended for
good QA/QC.

Observe maximum sample
holding or storage
periods recommended by
the Agency.  Documentation
of actual holding periods
should be carefully per-
formed.
           Figure 2:16.  Generalized ground-water sampling protocol

                                     110

-------
addition, this  information can be  useful when interpreting  monitoring




results. Low water levels may reflect the influence  of  a  nearby  produc-



tion well.   High water  levels compared  to  measurements  made at  other



times of the  year  are indicative of recent  recharge events.   In  rela-




tively shallow monitoring settings high water levels from  recent  natural




recharge events may result in dilution  of the  total  dissolved solids  in



the  collected sample.  Conversely,  if  contaminants  are  temporarily held



in an unsaturated zone above the geologic zone being monitored, recharge



events may "flush" these contaminants in the shallow ground water system




and result in higher levels of some constituents.



     Documenting  the  nonpumping water  levels  for all  wells  at a site




will provide  historical  information on the hydraulic conditions at the



site.   Analysis of this  information will reveal changes  in  flow  paths




and  serve  as  a  check  on  the  effectiveness  of  the  wells  to  monitor



changing hydrologic  conditions.   This  information  is  also essential  to



develop an understanding  of  the seasonal  changes  in water  levels and



associated chemical concentration variability at the monitored site.





Purging



     The volume of stagnant water which should be removed from the moni-



toring  well  should  be calculated from  the analysis   of field hydraulic



conductivity  measurements.   Rule  of thumb guidelines for the volume of



water  which should be removed from a  monitoring well prior to  sample



collection  ignore  the  actual  hydraulic performance  of  the sampling



point.    These  3~,   5-   or  10-well  volume  purging guidelines   are   a



liability  in  time,   expense  and  information  return from  the sampling




activities.
                                   Ill

-------
     The calculated well purging requirement should also be monitored in

the field by the in-line monitoring of the well purging parameters (e.g.

Eh, pH, T, and  n~1).   In-line measurements provide the most representa-

tive  data for  these  constituents  and  verify the  reliability  of  the

hydraulic  evaluation  of  the  sampling  point  or  well  (2,77).    These

chemical constituents further aid in the interpretation of water quality

changes as they are affected by hydrologic conditions.  Modifications to

the electrode  cell in these  flow-through  instruments have resulted in

their  improved  performance  in the field  (78).    A photograph of  this

instrument is provided in Figure 2.17.

     For  example,  the calculated   well purging requirement  (e.g.  >90%
aquifer water)  calls  for  the  removal  of  five  well  volumes prior  to
sample collection for a particular well.  Field measurements of the well
purging parameters  have  historically confirmed this  recommended  proce-
dure.   During a  subsequent  sampling effort,  twelve well  volumes  were
pumped before stabilized well  purging  parameter readings  were obtained.
Several possible   causes  could   be explored:   1) A  limited plume of
contaminants may  have  been  present  at  the well  at  the  beginning  of
sampling  and inadvertently  discarded while  pumping  in  an  attempt  to
obtain  stabilized  indicator parameter readings;  2) The hydraulic prop-
erties of  the  well have changed  due  to silting or  encrustation  of  the
screen  indicating  the  need  for  well  rehabilitation  or  maintenance;
3) The flow through device used for measuring  the   indicator  parameters
was malfunctioning; or H) The  well  may have  been tampered with  by the
introduction of  a contaminant  or  relatively  clean  water source  in an
attempt to bias the sample results.

     Documentation of the actual well purging process employed should be

a  part of  a  standard field sampling  protocol.   Figure 2.18  presents  a

one-page  form  which  may   be  used   for   documenting  field  sampling

operations at each sampling point.


Sample Collection

     The initial hydrologic  and well  purging measurements necessary for

reliable  ground-water  sampling should  be  entered   into  the  same  field
                                  112

-------
Figure 2.17.   A well-head instrumentation package for Eh,  pH,
          conductivity and temperature measurements

                            113

-------
                          GROUND WATER SAMPLING RECORD
 Facility name

 Hell number
                                                     Date
                   Well depth
                             Well diameter
                                                           Casing Matl
 Sampling crew

 Type of purap
                                             tubing
 Weather conditions


 Time
Water  Pump   Volume   Pumping  Sample    Temp
level   on    pumped    rate    start/end  (°C)
             Cond
Eh     £H    (uS)
Sample delivered to
                                               By
   Figure  2.18.   Suggested recording format for  well  purging
                         and sample collection
                                    114

-------
notebook as that of the discrete samples  for  field or  laboratory deter-



minations.  Regardless of the   level of analytical detail in  the moni-



toring program,  it  is  essential that all samples  be  collected properly



and that  the  actual conditions during  each sample collection  are com-



pletely documented.  One  member of  the sampling  staff  should be desig-




nated as responsible for this documentation.



     The  format  for documentation  should be clear and  constant during




the overall  program.   A  set of useful forms for field  collection and



measurement are  presented in Tables  2.8 and 2.9.  They are largely self-



explanatory.   It is useful to standardize the format, particularly where



field  personnel  are responsible for splitting  samples  for field spikes



or  blind control samples.   It is  recommended  to  inscribe  the  bottles




with  an  identifying  marking  which,  when  combined  with  the  date  of




sampling,  will uniquely identify it in  a  sampled  set.



     Water samples should  be  collected when the solution chemistry of



the ground water being pumped  has stabilized  as indicated by  pH,  Eh, JT1



and T  readings.   In practice,  stable sample  chemistry is indicated when



the purging  parameter measurements have  stabilized  with ±1056 over 2



 successive well  volumes.   First, samples  for  -volatile  constituents, TOG,



TOX and   those  constituents  which require  field filtration or  field




 determination should be  collected.  Then large volume  samples  for extrac-



 tible organic compounds,  total metals or  nutrient anion determinations




 should be collected.



      All  samples  should  be collected  as  close as possible to the well



 head.   A "tee"  fitting placed  ahead of .the in-line device for measuring



 the well  purging  parameters makes   this more convenient.   Regardless  of
                                    115

-------















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 the sampling mechanism  in  use or the components of  the  sampling  train,

 upgradient wells  should be sampled first  followed  by the  downgradient

 wells to  minimize  the potential  for cross-contamination.   Laboratory

 detergent solutions  and distilled  water should  be  used  to  clean  the

 sampling train  between  samples.   An  acid  rinse  (0.1  N HC1) or solvent

 rinse (i.e.  hexane or  methanol)  should be  used to  supplement   these

 cleaning steps  if  necessary.   All  cleaning  should  be followed by dis-

 tilled water  rinses which may  be  saved to check cleaning  efficiency.

      Adhesive labels or  "indelible"  markers can present sample identifi-

 cation problems, particularly  when a variety of samples, split-samples,

 standards  and blanks are transported in ice chests.  The markings can be

 floated  off or  abraded into  an illegible  condition during transit.

      Serious  problems  in  sample handling  and storage  can  result  if
                  )•
 extreme  care  is not taken  during transport  and   storage.  All ice, ice

 packs, and ice-chests  should  be  prepared in  areas  that are remote from

 reagent  and solvent storage of any  kind!   Further,  the interim storage

 of these materials  should also be remote from reagent or solvent storage

 areas.   These  precautions  will  minimize the  effect  of  contamination

 errors on the results (79).


 Filtration

     There  are1 instances  which  arise,  even with  properly  developed

monitoring wells,  that  call for  the filtration of water samples.   It

 should  be evident, however,   that  well  development  procedures  which

require two to  three hours  of  bailing, swabbing, pumping  or  air  purging

at each  well  will  save  many hours  of  time  in sample filtration.   Well

development may have to  be repeated at  periodic  intervals  to minimize
                                  118

-------
the collection of  turbid  samples.   In this respect, it is  important  to
minimize the  disturbance  of fines  which accumulate in  the well  bore.
This can be achieved by careful placement of the sampling  pump intake  at
the top of the screened interval, low pumping rates, and by avoiding the
use of bailers (60).
     It is advisable to refrain from filtering TOG, TOX or other organic
compound samples  as   the  increased handling required may result  in the
loss  of chemical  constituents   of  interest.   Allowing  the  samples  to
settle  prior  to  analysis  followed  by decanting the sample is preferable
to filtration in  these instances.   If  filtration is  necessary for the
determination of  extractable organic compounds, the filtration should be
performed  in  the laboratory by the application of N2  pressure.   It may
 be necessary  to  run  parallel  sets  of  filtered  and  unfiltered samples
with standards to establish the recovery of hydrophobia compounds when
 samples must  be.filered.   All of the materials'  precautions  used  in  the
 construction  of  the  sampling  train should  be  observed for  filtration
 apparatus. Vacuum filtration of ground-water samples  is not recommended.
      Water samples for   dissolved inorganic  chemical  constituents (e.g.
 metals, alkalinity and anionic species) should be filtered in the  field.
 The preferred arrangement is an in-line filtration module which utilizes
 sampling  pump pressure  for  its operation.   These modules  have  tubing
 connectors on the  inlet and outlet  parts and  range  in  diameter  from
 2.5-15  cm.   Large diameter filter holders,  which  can  be rapidly dis-
 sembled for  filter  pad replacement are  the most  convenient and efficient
 designs  (80,81).
                                    119

-------
      The  choice of  filter  media must  be  made  on  the  basis  of  its



 exposure  to the  water  samples   and  the  degree  of  analytical  detail



 required  for   those  samples.    Clearly,   water  samples  which  may  be



 contaminated with  organic  solvents  limit  the use  of  organic  filter



 media,  such  as cellulose  nitrate,  cellulose  acetate  or  polycarbonate



 filters.   In these cases  glass fiber  or Teflon(R) filter  media should  be



 used.   Glass fiber filters  should be  acid rinsed followed by distilled



 water  rinsed prior to  their use  for  filtering trace metal or nutrient



 samples.   Once  an  appropriate filter media   has  been selected,  it  is



 advisable to choose a 0.45  yM nominal  sized filter.  The  final selection



 of  the material  and  type  of filter  pad  should  be made  carefully,   as



 there  are considerable differences between "screen"  or "depth"  filtra-



 tion media (82).   Screen filters  are typically less  than 50  pM thick



 (e.g. polycarbonate filters)  which tend to  load up and clog more rapidly



 than the  depth-type filters.  Sampling staff should be trained in proper



 procedures for  filter pad replacement, since fine  particles  can easily



 be transferred to the outlet  side  of a dissembled filter module.   Sloppy



 technique may result  in solids breakthrough and biased samples.   After a



 filter  pad is charged,  the  initial  50-100 mL should be  discarded as  a



 rinse.    Even   if very  careful  procedures are  followed,  clogging  and



 small particle breakthrough are real problems which must be addressed on



 a case by case basis  (82,83).





Field Versus Laboratory Determinations




     Representative sampling  results  from the execution  of  a  carefully



planned sampling protocol  which   establishes necessary hydrologic  and
                                  120

-------
chemical data for each sample collection effort.   An important consider-
ation for maintaining'sample integrity,  after collection,  is to minimize
sample  handling  which may  bias subsequent  determinations  of  chemical
constituents.  Since  opportunities to collect high quality data for the
characterization  of  site  conditions  in  time  may  be limited,  it  is
prudent  to  conduct sample  collection as carefully  as  possible from the
outset.   It  is  preferable to  bias  data on the  conservative side  when
doubt  exists  as  to the sensitivity of specific chemical constituents to
sampling or handling errors.  Repeat sampling or  analysis   cannot  make
up  for lost  data collection  opportunities.
      Samples  collected  for  specific chemical constituents may require
modifications of  recommended  sample handling and  analysis  procedures.
Matrix  effects   and   extended  storage  periods   can  cause  significant
 problems in this regard.  It is frequently more effective  to  perform a
 rapid  field  determination  of specific  inorganic  constituents   (e.g.
 alkalinity,   pH,  ferrous iron,  sulfide,  nitrite  or  ammonium)  than to
 attempt sample  preservation followed  by laboratory  analysis of  these
 samples.  There are several good references to  guide  the  development of
 field  analytical  procedures (1,2,31).   Korte and  Ealey  (84)  have pre-
 pared  a useful  field analytical  guide.   However,  their  recommendation
 not  to filter  alkalinity  samples  is  not supported by the literature.
 pressure  filtration  is necessary to insure that the  alkalinity results
 are  reliable for  subsequent   calculations  of  solution chemistry  equi-
 libria (85).
       Criteria for the  selection  of  appropriate analytical metho-ds vary
 somewhat  and the degree of analytical  detail required for  ground-water
                                    121

-------
  monitoring programs  is increasing..  It is advisable to select  field and
  laboratory  analytical  methods  carefully  after  consultation  with the
  proper authorities.  One should  keep in mind that methods for drinking
  water  or wastewater may encounter significant  interferences when applied
  to contaminated ground-water  samples.
  Blanks,  Standards  and Quality Assurance
      The use of field  blanks,  standards  and  spiked samples  for  field
  QA/QC  performance   is  analogous  to  the  use  of  laboratory  blanks,
  standards  and procedural or validation standards.   The  fundamental  goal
  of  field QC is  to  insure  that  the sampling protocol is being executed
  faithfully  and  that situations  leading  to error  are recognized  before
  they seriously  impact the  data.   The  use  of field  blanks and standards
 and spiked samples can account for changes in  samples which occur after
 sample collection.
      Field blanks and standards enable quantitative  correction  for  bias
 (i.e.,  systematic errors),  which arise due to  handling,   storage, trans-
 port and laboratory procedures.   Spiked samples and blind  controls  pro-
 vide the means to  correct combined sampling and analytical accuracy or
 recoveries  for  the  actual conditions  to  which  the samples  have   been
 exposed.    All  QC measures should be  performed  for at   least  the  most
 sensitive chemical  constituents  for each  sampling  date.   Examples of
 sensitive  constituents   would  be:    benzene  or   trichloroethylene as
 volatile  organic  compounds and lead or iron as  metals.   It is difficult
 to  use  laboratory blanks alone for  the determination of  the  limits of
 detection or quantitation. Laboratory distilled water may contain higher
levels   of   volatile organic  compounds (e.g.   methylene  chloride) than
                                  122

-------
those of uncontaminated   ground-water   samples.  The   field  blanks  and



spiked samples should  be  used for this purpose, conserving the  results




of lab blanks as  checks on  elevated  laboratory   background levels.   The




usefulness  of  spiked  samples  should be obvious.   Whether the  ground-



water  is  contaminated with interfering compounds or not,  these  samples




provide  a  basis  for  both  the  identification  of  the constituents  of



interest and the  correction of their recovery (or accuracy) based on the



recovery  of the  spiked standard compounds.  For  example,  if  trichloro-



ethylene  in a spiked  sample  is  recovered at a mean level of 80$ (-20%



bias), the  concentrations of  trichloroethylene determined  in  the samples




for  this sampling  date may  be   corrected  by a  factor of 1.2  for low




recovery.   Similarly,  if  50%  recovery  (-50* bias)  is reported for the



spiked standard,  it is likely that sample handling or  analytical proce-



dures are  out  of  control  and corrective measures  should be  taken  at



once.  It  is  important to   know  if the laboratory has performed  these



 corrections or taken  corrective  action  when they report  the results  of



 analyses.   It  should  be  noted  that   many regulatory agencies  require



 evidence of QC  and analytical  performance  but do not generally accept




 data which has been corrected.



      Field  blanks, standards and blind  control  samples  provide  inde-



 pendent checks on  handling and storage as well  as the performance of the



 analytical laboratory.   It should be  noted that ground-water analytical



 data is  incomplete unless the analytical   performance data  (e.g.  accu-



 racy, precision, detection,  and quantitation  limits) are reported -along



 with each  set of results.  Discussions of whether significant changes  in
                                    123

-------
 ground-water quality have indeed occurred must be tempered  by  the  accu-



 racy and precision performance for specific chemical  constituents.



      Table 2.10 is a useful guide to the preparation  of  field standards,



 and spiking solutions for split samples.  It is important  that  the  field



 blanks and standards   be made on the day of sampling and are  subjected



 to   all conditions  to  which  the samples  are  exposed.   Field spiked



 samples or  blind controls should  be prepared in the  field by spiking



 with concentrated stock standards in an  appropriate background  solution.



 The choice of  spiking  solution is particularly critical where volatile



 organic compounds are of   concern  (e.g. TOG, TOX and  purgeables).   In



 this  case,  pure  poly(ethylene glycol)   or water:poly(ethylene glycol)



 mixtures are  very useful  (86).   The  use  of  methylene chloride  as  a



 standard compound should be avoided.  Additional  precautions should be



 taken  against the depressurization of samples during air  transport and



 the effects  of  undue  exposure  to  light  during sample  handling  and



 storage.  All  of   the QC  measures noted  above will provide both a basis



 for high quality  data reporting and a known degree of confidence in data



 interpretation.   Well  planned  quality control programs will  also  mini-



 mize the uncertainty in  long-term trends when  different personnel  have



 been involved in  sample collection and analysis.




 Sample Storage and Transport




     The storage  and transport  of  ground-water samples  are often  the



most neglected elements of  the sampling  protocol.   Due care must  taken



 in  sample  collection,  field  determinations  and  handling.   If proper



planning of transport is  neglected the  samples may  be  stored  for  long



periods  before  laboratory analysis.   Every effort   should  be  made to
                                  124

-------





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 inform the laboratory  staff of the approximate time of  arrival  so  that



. the most  critical  analytical determinations can  be  made within  recom-



 mended storage  periods.    This  may require  that  sampling schedules  be



 adjusted so  that the  samples  arrive at  the laboratory during  working



 hours.




      The documentation  of  actual  sample storage and  treatment  may  be



 handled by the  use of  chain of custody  procedures.   An  example of a



 chain of custody form  is shown in Figure  2.19.   Briefly,  the chain  of



 custody record should  contain the  dates  and times  of  collection, receipt



 and completion of all  the analyses on a particular set   of samples.   It



 frequently is the only record of the actual storage period prior to the



 reporting of  analytical results  that  exists.  The sampling staff members



 who initiate  the  chain  of  custody should require that a copy of the form



 be  returned to them with the analytical report.  Otherwise, verification



 of  sample storage and handling will be incomplete.




     Sample  shipment  arrangements  should  be  planned  to  insure  that



samples are neither lost nor damaged   enroute to  the  laboratory.   There



are  several  commercial suppliers of sampling kits which  permit refrig-



eration by freezer packs   and include  proper  packing.   It may  be  useful



to include special  labels   or  distinctive  storage   vessels   for acid-



preserved samples to accommodate shipping restrictions.
                                  126

-------
                         CHAIN OF CUSTODY RECORD
Sampling Date
                            Site Name
Well or Sampling Points:
Sample Sets for Each;  Inorganic, Organic, Both

Inclusive Sample Numbers;

Company's Name	 Telephone (
Address
        number   street

Collector's Name

Date  Sampled 	
                                  city
                     state

                Telephone (_
                                                                 zip
                        Time Started
                Time Completed
 Field Information  (Precautions,  Number  of  Samples,  Number  of  Sample
 Boxes, Etc.):
 1
     name
                              organization
                                                         location
     name
                              organization
                                                         location
 Chain  of  Possession  (After  samples  are transported  off-site  or to
 laboratory):

                                                       ___ 	 (IN)

                                                     	 ;	(OUT)

                                                     	 (IN)

                                                                   (OUT)
1.
2.
    signature
                             title
    name (printed)
    signature

    name (printed)
date/time of receipt

title

date/time of receipt
 Analysis Information;


     Aliquot

 1 .
 2.'
 3.
                 Analysis Begun             Analysis Completed
                  (date/time)    Initials      (date/time)       Initials
  5.
                 Figure 2.19.  Sample chain of custody form

                                    127

-------
                                 SECTION 3
                       RECOMMENDED  SAMPLING PROTOCOLS
      The  selection  of methods and materials for  drilling  and well con-

 struction,  sampling and sample handling  should be based  on  a complete

 evaluation of site  conditions, the analytes of interest and the informa-

 tion needs  of the  program.   Integrating  all  of these elements  into  a

 reliable sampling protocol must be done in phases as  information  on the
                                                                     /
 actual conditions at a site is collected.   Sampling mechanisms and mate-

 rials are central to  effective monitoring  efforts.  However,  mechanisms

 and materials' selections are only the basis for  the  development  of the

 sampling protocol.   The preliminary protocol must  be  documented and all

 personnel  involved  in the  effort  should  be  well  acquainted with  it.

 Then the sampling protocol  can be refined  and targeted in development to

 meet the critical information  needs of  the  overall program.

      In this section,  specific recommendations  are made for preliminary

 sampling protocols  applicable to both contaminant detection and assess-

 ment programs. General  guidelines  are  presented with  a  step  by step

 description  of the  procedures  to develop of specific sampling protocols

 for  a variety  of  monitoring applications.



 THE  BASIS FOR SAMPLING PROTOCOL DEVELOPMENT

     The individual  elements  of effective   sampling  protocols  have been

 reviewed in Section  2  of  this  guide.   The  generalized sampling protocol

 presented in Figure  2.16  provides a review  of the procedures undertaken

at  each step.    Figure  3.1  provides  a prioritized  schematic for  the

execution of steps  within the overall  protocol  which should  guide  the
                                 128

-------
     Step

Well Inspection

Well Purging
 Sample Collection
 Filtration*
 Field
.Determinations**
           Procedure

     Hydrologic Measurements
           +
     Removal  or Isolation of
     Stagnant Water
           *
     Determination of Well-Purging
     Parameters  (pH, Eh, T, a"1)**
Unfiltered
                       Field Filtered*
 Preservation
 Field Blanks
 Standards
                   Volatile Organ!cs, TOX
                       4-
                   Dissolved Gases, TOC
                       4-
                   Large Volume Samples for
                   Organic Compound
                   Determinations
     Essential elements

Water-level Measurements

Representative Water  Access


Verification of Representa-
tive Water Sample Access

Sample Collection by
Appropriate Mechanism

Minimal Sample Handling

Head-Space Free Samples
                                             Minimal Aeration or
                                             Depressurization
Assorted Sensitive
Inorganic Species
N02~, NHi, + , Fe(II)
                    (as needed for  good
                    QA/QC)
                                           Alkalinity/Acidity**
                                           Trace Metal Samples
                        S=, Sensitive
                        Inorganics

                                4
                        Major Cation and
                        Anions
 Storage
 Transport
 Minimal Air Contact,
 Field: Determination

 Adequate Rinsing Against
 Contamination

 Minimal Air Contact,
 Preservation
                                              Minimal Loss of Sample
                                              Integrity  Prior to Analysis
  *Denotes samples which should be filtered in order to determine dissolved constituents.
   Filtration should be accomplished preferably with in-line filters and pump pressure or by
   N? pressure methods.  Samples for dissolved gases or volatile organics should not  be
   filtered.  In instances where well development procedures do not allow for turbidity-free
   samples and may bias analytical results,  split samples should be spiked with standards
   before filtration.  Both spiked samples and regular samples should be analyzed to
   determine recoveries from both types of handling.

  **Denotes analytical determinations which should be made in the field.
  Figure 3.1.   Generalized flow diagram of ground-water sampling  steps
                                            129

-------
 planning of  sampling efforts.   Essential considerations for  the  relia-



 bility  of  each step  are also provided  in  the figure  to  aid  planning



 specific efforts.  The  planning should  be coordinated with supervisory,



 field, and laboratory staff.




      Since the  sampling mechanism provides  the sample for further  pro-



 cessing, it is  useful  to consider the  degree  of  analytical  detail and



 the reliability of specific sampling mechanisms before the remainder of



 the protocol is developed.   Figure 3.2  provides  a matrix  which  allows



 the comparison -of  sampling mechanism  reliability with the sensitivity of



 various  classes of constituents to sampling  error.   This matrix  summa-



 rizes  the  detailed recommendations  provided  in  Section  2.    Its  use



 should enable the  initial choice of sampling mechanism which will serve



 the planning needs  for  a preliminary sampling protocol.  Once the  choice



 of  sampling mechanism  has  been made, step-by-step  sampling procedures



 for specific monitoring applications may  be designed.




     Appropriate ground-water sampling procedures  should  be selected on



 the basis  of  collecting  the  most  reliable  samples  possible for  the



 specific  analytes  of  interest.   For  purposes   of discussion, one  may



 categorize  monitoring efforts into two  broad  classes  (i.e.,  detection



 and assessment)  according to the level of analytical detail  sufficient



 for the information needs of the program.






SAMPLING PROTOCOLS FOR DETECTION MONITORING




     In detection monitoring efforts,  the information needs are mainly



to  detect ground-water  contamination  and to  establish a  set of useful



ground-water quality data in the event that contamination  is  detected.
                                  130

-------
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131

-------
 Analyte Selection and Sampling Recommendations
      A list  of the corresponding regulated  parameters for a  detective
 monitoring effort is provided in Table 3.1.  The listing includes param-
 eters of  the following types:   well purging,  contamination  indicator,
 water quality and those that establish drinking water  suitability.   The
 well-purging parameters provide both a measure  of the  efficiency of  the
 well-evacuation procedures prior to the collection of  samples  and valu-
 able data (e.g. Eh, pH, Q-1,  T) for  the evaluation or  interpretation of
 water chemistry results.  The contamination  indicator parameters  (e.g.
 pH,  8~1,  TOC, TOX) may indicate whether or not  gross  changes in  ground-
 water solution composition have occurred  due  to a contaminant release.
 The  sensitivity of these  indicator  parameters is somewhat limited with
 the   exception  of  TOX  which  can  be  determined reliably at  sub-ppm
 (yg'lT1) levels.
      Water quality parameters  provide useful information for description
 of the ground-water system, particularly when  the regulated constituents
 (e.g.  Cl~, Fe,  Mn,  Na+,  SGij= and  phenols)  are supplemented  with the
 major cations and  ions  which  usually comprise  the bulk of the dissolved
 solids in  natural water samples.   The water  quality parameters  may be
 used  as a basis for comparison in  the event that the  monitoring program
 is triggered into an assessment phase.  More importantly,  the character-
 ization of  the inorganic  chemical composition of ground  water enables
 both  the quantitative interpretation  of the consistency of the  analyti-
 cal results  and the potential  to  calculate the chemical  speciation  of
specific dissolved  chemical  constituents. It  is the  speciation  of
chemical  constituents which enables the prediction of  their  reactivity,
                                  132

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         Table 3.1.   Recommended Analytical  Parameters  for Detective Monitoring
Type of parameter
Well-purging

Contamination
indicators
Water quality
Drinking water
suitability**
Type of determination
 Lab. (L),  Field  (F)
          F
                             ,L

                              L

                              L
                                                                      Analytes
        Required by regulation

pH,  conductivity (ST1)


pH,  ST1

Total organic  carbon  (TOC)
Total organic  halogen (TOX)
Cl~, Fe, Mn, Na+, SOjj"

Phenols
                        As, Ba.Cd, Cr,  F-,  Pb, Hg,
                        N03~, Se, Ag
                        Endrln, lindane, methoxychlor, toxaphene
                        2,4-D, 2,4,5-TP (Silvex)
                        Radium, gross alpha/beta
                        coliform bacteria
    Suggested for
    completeness
Temperature  (T)
Redox potential (Eh)
                                                                   Alkalinity (F) or
                                                                   acidity (F)
                                                                   Ca++, Mg++, K+, N
                                                                   POip, silicate,
                                                                   ammonium
  *  All parameters are required to be determined quarterly for the first year of network operation.

 **  These parameters are excluded from the annual reporting requirements of  RCRA after the first year.
                                                    133

-------
 solubility and mobility under the actual conditions   at   the  site.   [It



 should be noted  that  mass and charge   balance  consistency of the  ana-



 lytical  results is a pre-condition  for  the reliable   application of



 equilibrium speciation  models.]  The drinking water  suitability  param-



 eters are often  required  to  be  determined in the first  year  of network



 operation on a quarterly  basis  by  monitoring regulations.   They may be



 excluded from annual  reporting   requirement  in  succeeding years.   One



 year of quarterly data for these parameters may not be sufficient, since



 potable water wells may often be used as background (upgradient) compo-



 nents of a monitoring  network if the original upgradient  wells  of the



 network prove to be contaminated.  These requirements  may vary somewhat



 based on current monitoring  regulations.   Field  blanks,  standards  and



 spiked samples should  be  done at the same degree of replication for all



 parameters on each  sampling date.




      In  summary,  recommended   parameters   for   detective  monitoring



 programs  provide a  minimum capability to detect contamination and to



 serve  as  a basis for comparison  and  planning, should  the program  enter



 the  assessment  phase.    Depending on  the  hydrologic   conditions at  the



 site, -higher  sampling frequency  (e.g. monthly) will provide a better  set



 of baseline data for future trend  analysis  or  upgradient-downgradient



 comparisons.




     Many ground-water monitoring programs will entail  the determination



 of the sensitive chemical  parameters  noted  in Table 3.1.  These param-



 eters  demand  the  careful  selection  of both field and  laboratory sample



handling (e.g. pumping, transfer, collection  and storage)  and analytical



procedures.   For  example, levels  of pH, Eh, TOG, TOX,   alkalinity,
                                  134

-------
ammonium, Fe and other trace metals are prone to serious bias  (i.e.  loss
or inaccuracy) and imprecision  (i.e. inconsistent duplicates,  high  ana-
lytical variance) if volatilization, aeration or degassing occurs during
sample handling or analysis.  The severity of these problems  will  be  a
function of solution composition, field conditions and the complexity of
the  actual procedures  employed.    It  should  be recognized   that  the
simplest  procedures  which minimize sample handling and exposure to the
atmosphere or  agitation will  provide  the most reliable results.   There-
fore,  the  use  of a sampling mechanism which  provides flow sufficient for
well  purging  and a steady stream of ground-water for the in-line deter-
mination  of  well-purging  parameters  (and  in-line filtration)is  pre-
ferred.   This   type  of  mechanism  will  enable the  controlled transfer and
collection of discrete samples  for both field and laboratory  determina-
 tions of  specific chemical parameters.  Where  ground-water availability
 is a  problem,  discrete samples must  be  collected  with every effort  to
 preserve  sample   integrity.  A schematic diagram of recommended sample
 collection, and handling methods for detection monitoring programs,  is
 shown in Figure 3.3.   Specifics  on sample handling and preservation  are
 provided   in  Table 3.2.   These recommendations 'have  been based on  the
 available  information from the literature.

 ASSESSMENT MONITORING
       The  information  needs  of assessment  monitoring  efforts  ai-e  more
 detailed  than  those   involved  in detection monitoring.   In detection
 monitoring,  the indication of contamination and the  establishment  of a
 basis for ground-water  quality comparisons  are the principal  goals.  In
 the  assessment  phase,  the nature, extent and dynamics of a contaminated

                                    135

-------
Parameters
(type)
Well-purging
(pH, Eh, T, 0-')





Contaalnatlon
Indicators
(pH, D 1)




(TOO, TOX)






Mechanism
Pump
(T.S.P.O)

Flow rates:
0.1-1.0 L/mln
Crab
(T,S,G,P,0)
Pump
(T.S.P.O)

Flow rates:
0.1-1.0 L/mln
Crab
(T,S,G,P,0)
Pump
(T,S preferred;
0,P only where
supporting data
exists)




Grab
(T,S,G preferred;
0,P only where
supporting data
exists)
Hydrogeologic Cc
	 >100 mL/min yield
Flowing samples
Positive displacement
bladder pump
(air, N2)




Positive displacement
bladder pump
(air, H2)




(Mechanisms as above
operated at f!6w
rates not to exceed
100 raL/min)
W mL vials filled
gently from bottom
up and allowed to
overflow + Teflon
capped H/O headspace

iditions (yield capability)
<100 mL/min yield
	 Discrete samples 	



Dual check valve bailers
"thief" samplers




Dual check valve bailers
"thief" samplers
(Volatile fractions of TOC
and TOX may be lost
depending on conditions
and operator skill)




'to mL vials filled from bottom up
and allowed to overflow or gently
poured down the aide of the vial,
Teflon capped w/o headspace
                      Materials  In order  of preference include:  Teflon  (T);  stainless steel  (s);  PVC, polypropylene
                      polyethylene (P)j boroslllcate glass (G)j other materials:   silicone, polycarbonate,  mild steel
                      OtO. (0)

                                                                                    (continued on next page)
                              Figure 3.3   Recommended sample  collection methods for
                                              detective monitoring programs
                                                              136
.

-------
Parameters
( type)
Water Quality
Dissolved Gases
(02. CHi,, C02)
Alky/Aedy
(Fe, Mn, P0j|=, Cl",
Na+, 3014-, Ca++,
Hg++, K+, N03-.
Silicate)
(Ammonium, Phenols)
Mechanism
(material)*
Pump
(T,S,P,0)
Grab
(T.S.G.P.O)
Pump
(T,S,P,0)
Grab
(T,S,G,P.O)
Pump
(T,S preferred;
0,P only where
supporting data
exists)
Grab
(T,S,G preferred;
0,P only where
supporting data
exists)
Hydrogeologio Conditions (yield capability)
>100 mL/min yield
Flowing samples
(Mechanisms as above
operated at flow
rates not to exceed
100 mL/min)
Glass containers
filled gently from
bottom up and allowed
to overflow -» Teflon
capped w/o headspace
Positive displacement
bladder pump
(air, N2)
(Mechanisms as above
operated at flow
rates not to exceed
1000 mL/min)
Glass containers
filled from bottom
up
<100 mL/min yield
Discrete samples
(Not recommended)

Fe values sensitive to most
grab mechanisms
Large volumes required may have
to be sequentially collected and
filtered
(Volatile species may be lost
depending on 'conditions)
Glass containers filled from
bottom up
* Materials in order of preference  Include:  Teflon (T);  stainless  steel  (S); PVC, polypropylene,
  polyethylene (P); borosilicate  glass  (G);  other materials:  silicone, polycarbonate,  mild  steel,

                                                                       (concluded on next page)
                              Figure 3.3.   (continued)
                                               137

-------
Parameters
It.'Ps)
Drinking Hater
Suitability
(A3, Ba, Cd, Cr, Pb,
Hg, Se, Ag, N03-,
F-)
(Reaalning
Piraneters)
Mechanism
Pump
(T.S.P.O)
Grab
(T.S.G.P.O)
Pump
(T.S.P.O)
Grab
(T,S,G,P,0)
(both with
precautions if
radlologio hazards
exist)
Hydrogeologio Co
>100 mL/min yield
	 Flowing samples
Positive displacement
bladder pump
(air, ND)

Positive displacement
bladder pump
(air, N2)
Flow rates should
not exceed
1,000 mL/min
id It ions (yield capability)
<100 mL/min y,.eld
	 Discrete samples 	
Dual check valve bailers
"thief" samplers
(Volatile compounds may be
lost depending on conditions)
Materials  In order of preference include:   Teflon (T); stainless  steel (S);  PVC,  polypropylene
polyothylena (P), borosilicate glass (a),  other  materials:   silicone,  polycarbonate,^? steel!
                           Figure 3.3.    (concluded)
                                           138

-------
  Table 3.2.   Recommended  Sample Handling and Preservation Procedures
                     for a Detective Monitoring Program*

Parameters
(type)
Well purging
pH (grab)
IT1 (grab)
T (grab)
Eh (grab)
Contamination
indicators.
pH, a"1 (grab)
TOG'
TOX
Water quality
Dissolved gases
(02, CHi), C02)
Alkalinity/
Acidity






(Fe, Mn, Na+,
K+, Ca++,
Mg++)
(P04=, Cl",
Silicate)
N03"
S0i4 =
NHi) +

Phenols

Drinking water
suitability
As,Ba,Cd,Cr,
Pb,Hg,Se,Ag



F~


Volume
required
1 sample**

50
100
1000
1000


As above
to
100

10 mL minimum
100

Filtered
under
pressure
with
appropriate
media
All filtered
1000 mL

§ 50

100
50
1)00

500



Same as above
for water
quality
cations
(Fe,Mn,etc.)
Same as
chloride
above

Container
(material)

T.S.P.O
T.S.P.B
T,S,P,G
T.S.P.G


As above
G,T
G,T

G,S
T.G.P







T,P


(T,P,G
glass only)
T.P.G
T,P,G
T,P,G

T,G



Same as
above



Same as
above


Preservation
method

None-Field Det.
None-Field Det.
None-Field Det.
None-Field Det.


As above
Dark, 1°C
Dark, 1°C

Dark, l»8C
1°C/None







Field acidified
to pH <2 with
HN03
1°C

1°C
1°C
1°C/H2SOn to
pH <2
1°C/H3POi) to
pH <1


Same as above




Same as above




Maximum holding period

<1 hr.***
<1 hr.***
None
None


As above
21 hrs.
5 days

<21 hrs.
<6 hrs.***/<2l hrs.







6 months^


21 hrs./7 days;
7 days
21 hrs.
7 days
' 21 hrs./7 days

21 hrs.



6 months




7 days


  Remaining
  organic
  parameters
As for TOX/TOC, except where analytical method
calls for  acidification of sample
                                                                  21  hrs.
  * Modified after Scalf et  al.  (3)
 ** It  is  assumed that  at each  site, for each sampling date,  replicates, a "field blank
     and  standards must be  taken at equal volume to  those of the samples.
*** Temperature correction must  be made for reliable  reporting.  Variations greater than
     ±10? may result from longer holding period.
  A In  the event  that HN03  cannot  be used because of  shipping  restriction,  the sample
     should  be refrigerated  to 1°C,  shipped  immediately, and  acidified on receipt at
     the  laboratory.    Container  should  be  rinsed with  1:1  HNOg  and included with
     sample.
                                          139

-------
ground-water  situation  must  be  characterized  sufficiently  to  plan



further  investigative or  remedial  action  activities*    The  level  of



detail required  in  assessment  efforts  may be  an order of magnitude more



complex  than  those  in the detective phase.   Therefore,  the reliability



of the data in space and time must increase proportionately.  Incomplete



characterization  of  a ground-water sample's  solution  composition could



lead to the incorrect assessment of the mobility or reactivity of poten-



tial contaminants.   The  three-dimensional extent  of  a contaminant pulse



or plume might be lost if  the  bias introduced into the determination of



the  principal contaminants  is high relative to  background  concentra-



tions.   Remedial action  or mitigative action decisions  should  be based



on a high quality  data  set which meets the information  needs  of  the



program.  Clearly the experience that operators  gain  during the detec-



tion  phase  of  monitoring will  prepare  them  for  reliable  assessment



activities.




     The well-purging and  contamination  indicator parameters are gener-



ally less sensitive  to gross sampling  and analytical  errors than chemi-



cal  constituents which  may  be  specific  components  of  a  waste  from  a



landfill, impoundment, waste-pile, spill  or storage  area.    Predictions



of the  major contaminants  involved and  the  subset  of  stable,  mobile



constituents that may be expected to be found  downgradient  must  be made.



     For exampie,assume that a well-executed detection monitoring effort



at a solvent  waste  transport  station disclosed  that  TOX   values  down-



gradient Sre  significantly different  from  those  collected during  the



past three  quarters  at  upgradient wells.   The  mean upgradient  value



differs from that downgradient by  100  ppb which is of  the  order  of five
                                  140

-------
times the mean precision of the TOX determinations at these levels.   The




TOG data, on  the  other hand, show no statistically  significant  differ-




ence' between the upgradient and downgradient wells.  Since the precision




of the TOG values are ±0.1 rng-L"^  at best, it is quite possible that the



present contamination is the result of halogenated'solvent releases.  In



this case it may  be  that  hydrocarbon solvents  or petroleum derived com-



pounds are the likely constituents of interest in the assessment phase.



     Reliable sampling  of   the TOX  in the  ground-water  at the site may




permit the scope  of  the initial assessment  to  be limited to halogenated




compounds.  Additional  data   would be helpful  if the analytical results



clearly reported  both volatile and  nonvolatile TOG and TOX.  If, in the



example above,  the   observed TOX increase was represented in a propor-



tional increase only in the volatile TOX, the purgable organic compounds



should be investigated  in the initial assessment activity.



     If  the  detective monitoring  results  disclose  only  secondary,



nonvolatile contaminants  (because the volatile fractions of TOG or TOX



were  lost  during sample  collection,  handling or  analysis),  the conse-



quences  of  relying on  a  poorly designed sampling protocol could be far



more serious.   Precision and  bias  for  determinations of the detective



monitoring  parameters  can  be controlled   in  the  ±10  to  50%  range.



However,  order  of magnitude  levels  of  variance or  loss  may enter  into



sampling  and  analytical  results  for   trace  constituents  at  the ppb



 (pig-LT^)  level.   Poor  precision and accuracy directly reduce the  power



of statistical  tests  for   cxomparison  of  background  and  potentially




affected  downgradient  conditions.
                                   141

-------
      As  the   information  needs  of  a monitoring  program  become more



 detailed it is   essential  to  establish control over  errors'.    Sample



 collection and handling problems for TOG and TOX which do not introduce



 additional bias  or imprecision above those  of the analytical methods may



 be expected  to  perform  adequately  for  specific inorganic  or  organic



 chemical constituents of a  contaminant release.   This will  be  true if



 the chemical  constituents  of  the  product/waste release are  known and



 their  mobility or  reactivity  in the subsurface  can  be reasonably pre-



 dicted.  The actual selection of  "facility-specific"  constituents also



 may be  very difficult to make if ground-water  quality has not been well



 characterized  in  the  detection monitoring phase.




     Given the wide  range  of potential  contaminants  (e.g.  potentially



 thousands  of waste  components  in RCRA, Appendix VIII, etc. listings) and



 those which may be  sensitive to sample collection or handling errors, it



 is  difficult to make  a priori evaluations of the adequacy of monitoring



 procedures  or  protocols.  However,  it is  clear  that  proven  sampling and



 sample  handling  procedures which  control bias  and  precision  at  compa-



 rable levels  of  analytical  method performance  are  most  reliable.   In



 this respect,  Fe, pH, TOX  and TOG results are  parameters which may be



 used to  gauge  the  utility  of  sampling protocols  used in detection  moni-



 toring for  application in contamination assessment work.  One may gener-



 alize reliable sample collection and handling protocols on this basis.



     Dissolved iron may be accepted as being representative  of inorganic



metallic species which are prone to oxidation and the formation of  solid



oxide or oxyhydroxide products.   The oxide products  have  very active



surfaces for the  sorption  of other metallic ions or organic  compounds.
                                  142

-------
If water samples are not carefully collected  (i.e. to exclude 0£ or gas




exchange), handled  (i.e.  filtered  under  N2  or  pump presure  prior to



acidification), the reduced iron in many samples would oxidize prior to



preservation  and this  reaction,   as  well  as the  inevitable sorptive




interactions, could seriously bias the analytically determined composi-



tion of' the  ground water  (87).   By  analogy,  the target chemical  con-



stituents in an assessment program for metallic contamination  (e.g. Cu,



Cr, Ni  from  an acidic  alloy  treating process waste) should be sampled



and handled  reliably using the  same procedures  which  permit reliable



dissolved iron  samples  to be taken.   It should be noted that although



many RCRA Appendix VIII  parameters  are metallic  and  may require  only



metal  determinations  in the  lab,  the actual  elemented speciation  will




impact  the reliability  of sampling  procedures.   This may  be  illustrated



by  inspection  of  Table  3.3.   Analysis procedures should  be  streamlined



to  facilitate screening of water  samples since  the  speciation of  the



metal may impact  on sample  preparations  and  all  the  steps which  precede



them  (i.e.   sample  collection,  transfer,  filtration,  preservation  and



storage).   It is difficult   to specify  the  optimum  sampling procedures



for water samples potentially contaminated with a variety of  uneharac-



terized waste mixtures.  However,   a sampling protocol  which  is  proven



reliable for difficult  or sensitive chemical constituents should perform



adequately for most  other parameters.  Figure 3.2 contains  a  matrix of



chemical constituents .and  appropriate sampling mechanisms.   An increase



in the  degree of  sampling  difficulty or sensitivity to  bias  of  a con-



stituent requires that  a more robust, fool-proof  sampling mechanism  be



used.   If alternative   sampling methods are utilized which are not well
                                   143

-------
Quantity
    1

    2

    1
    2
    3
    2
    2
  Table 3.3.   Equipment for Field Sampling
                             Item
Compressed  N2   cylinder   (301   ft3)   for  bladder  pump
sampling oxidation sensitive constituents if needed
Scuba  tanks  (compressed  air)  (80  ft3  + 50  ft3)   for
bladder pump
Alkalinity   box-  (battery   operated   pH   meter   with
temperature  compensation,  electrode,  battery  operated
magnetic stirrer, buret, titrant, beakers)
Flow through cell in box with 3-way valve system to route
pump output to cell (e.g. pH, 2 redox, temp, electrodes +
conductivity cell) or to sample/waste (ref.  Figure 2.18)
Meter  box  (3-  pH meters (as above) +  1  battery operated
temperature compensated conductivity bridge) (ref. Figure
2.18)
Regulators for gas cylinder + scuba tanks
Buckets (15  L)  and graduated cylinder  (5 L)  to  measure
purge volume and sample waste
Dissolved oxygen field  kit  (Modified  Winkler Method (46)
200 mL titration volume)
5 gallon (LDPE) water jugs for deionized water
Sampling  pumps  (primary  plus   a  backup and  an  extra
bladder  assembly)  Teflon/Teflon bladder  and  Stainless
Steel/Teflon bladder
Pump tubing sets (Teflon) (1 air, 1  water, @ 50' + tubing
holder, primary plus backup).  Tubing diameter  should  be
no less than 1/4" o.d.  and the larger diameter  sizes will
minimize   tubing   material   effects    if    they   are
anticipated)
Pump control box with tubing
Gas manifold  (to  operate   multiple   pumps  from  same
compressed gas supply)
Steel measuring tape
Grass whip
Shovel
                                 (concluded  on  next page)
                                  144

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                         Table 3-3.
Quantity

    1


    1
    3
    4

    3
                      (concluded)
                             Item
Miscellaneous  box  with  (6  boxes  Kimwipes,   3  boxes
disposable gloves, aluminum foil, duct  tape)

Miscellaneous  box  with  (pH   buffers,   deionized  wash
bottle, Erlenmeyer  flasks,  beakers, graduate  cylinders,
pasteur pipettes, bulbs, cone. HNOg acid, cone. HC1 acid,
filter membranes, filter holders)

Shock cords

Coolers (insulated, 64 qt.,  54 qfr, 44 qt - one each)

Toolboxes
  * Sample bottles for samples, spiked samples and e;xtras
 ** Prepared  bottles  for  field  blanks  and  standards
      solutions
*** Sampling log, field notebooks, chain of custody forms
                                            with  spiking
                                   145

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referenced,  supporting accuracy  and  precision data should  be provided

for  the specific constituents of interest.   Regardless  of  the sampling

mechanism used, the elements of the generalized sampling protocol should

be documented completely.


Field Sampling Procedures

     This section  of  the guide  is  presented as an  example  of "how-to"

collect samples as  drawn  from  the authors'  experiences.   Refinement and

modification will  be  necessary for  application to  specific  sampling and

analytical  needs.   In large  measure,  the  degree  of  preparedness  and

skill which these  individuals  take into the  field will determine  the

actual number of samples  which can  be collected.   A well prepared  team

of three  individuals  can usually  sample  between  4-6  monitoring wells

(0-75 ft. deep) in a full 8-hour day,  exclusive  of  travel  time.  Given

the range of field or hydrogeologic conditions, network complexities and

the  analytical  detail  which  ground-water  monitoring  investigations

demand,  no single example can  provide all of the elements needed in the

sampling protocol.   The following  discussion  should  provide  the basis

for the application of effective sampling procedures for either  detec-

tion or  assessment monitoring investigations.

     The following  steps  in a sampling  protocol are covered  in  detail

below:

          Sampling Equipment Setup,  Well  Inspection and
          Water Level  Measurement

          Verification of  Well  Purging Requirements

          Sample Collection/Filtration/Field Blanks  and Standards
                                  146

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          Field Determinations



          Sample Storage/Transport



     The importance  of  careful integration of  the  efforts of sampling




staff at each point  should  not be  underestimated.   Mistakes, lost data



or biased results  may exact a heavy  price  if sampling efforts are not



well planned.  The same care taken in the laboratory to prevent mishaps




or contamination should be followed in the field.   It  should be obvious



that smoking or eating in the  vicinity of the well  head, pump output or




field analytical setups is strongly discouraged.





Sampling Equipment Setup, Well Inspection and  Water  Level Measurement



     It is a good practice to have  a detailed  list of  all sampling mate-




rials and supplies.   The list  should  be reviewed  before the sampling



staff leaves for  the field site.   This  somewhat tedious procedure will



cut down on  the frustration or anxiety which may arise later because of



missing equipment, reagents or bottles.   An example  of a sampling equip-



ment list is shown in Table 3.4 which includes the  basic gear needed to



conduct routine  sampling and  field activities.   The list  is reasonably



complete  for a  protocol  based on  the  use of  a positive  displacement



bladder pump which is sufficient for the well-purging and sample  collec-




tion requirements of many monitoring situations.



     On arrival  at the  well-head,  the condition  of  the surface seal  and




well protector should be examined to  see  if  any  evidence  of   frost-



heaving,  cracks  or  vandalism  are  observed,  they should be  recorded  in



the field notebook.  The area  around the well may have to  be cleared  of



weeds  or  other materials  prior to beginning the sampling activity.   A



drop  cloth should then  be  placed  on the  ground  around  the well  head,
                                   147

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          Table 3.4.   Metallic Species in RCRA Appendix  VIII
               Which Require Only Metal Determinations
* Antimony NOS
  Arsenic acid
* Arsenic and compounds, NOS
  Arsenic pentoxide
  Arsenic trioxide
* Barium and compounds, NOS
  Barium cyanide
* Benzenearsonic acid
* Beryllium and compounds, NOS
* Cadmium and compounds, NOS
  Calcium chromate
* Chromium and compounds, NOS
  Copper cyanide
* Dichlorophenylarsine
* Diethylarsine
* Hydroxydimethylarsine oxide
  Lead acetate
* Lead and compounds, NOS
  Lead phosphate
  Lead subacetate
* Tetraethyl lead
* Mercury and compounds, NOS
* Mercury fulminate
* Nickel and compounds, NOS

NOS:  Not otherwise specified; signifies those members of the general
      class not specifically listed by name in Appendix  VIII.

   *  Metallic species which may exhibit markedly different properties
      (e.g.  solubility, volatility, reactivity) from inorganic ions or
      complexes in ground water
*.Nickel carbonyl
  Nickel cyanide
  Osmium tetroxide
* Phenylmercury acetate
  Potassium silver cyanide
* Selenium and compounds,  NOS
  Selenious acid
  Selenium sulfide
* Selenourea
* Silver and compounds, NOS
  Silver cyanide
  Strontium sulfide
  Thallic oxide
  Thallium acetate
* Thallium and compounds,  NOS
  Thallium carbonate
  Thallium chloride
  Thallium nitrate
  Thallium selenite
  Thallium sulfate
  Vanadic acid,  ammonium salt
  Vanadium pentoxide
  Zinc cyanide
                                 148

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particularly if  the  land surface  is  disturbed or potentially contami-

nated.  This precaution will save  time  and the work of cleaning equip-

ment  or  tubing  should  they fall  on the  ground  during preparation or

operation.   The well  protector should  then   be  unlocked and  the  cap

removed from the top  of the well.   The  previous record of water levels

for the well should  be  consulted prior  to  chalking  the steel tape  and

making three  successive measurements of the  static water  level.    The

readings should  be recorded to  the nearest  ±0.01 ft.   If  the  well  has  a

history of  contamination,  the water level  measurements  should be  made

with  surgical  gloves  on  and  the tape  should be rinsed with distilled

water and wiped dry  with lint-free towels  as  it  is  wound on the  reel.

While the water level  is  being measured,  the other sampling personnel

should prepare to set up the pumping and flow-through measurement  equip-
                                                     i
ment  and  the   instrumentation  for  analytical  field  determinations.

Blanks  and  standards should  be titrated  for  alkalinity and dissolved
                 !
oxygen  determinations at  this time.   Also, the  pH  meters,  Eh electrode

combinations and the conductivity bridge should be calibrated (78).  The

assembly  of  the Teflon and stainless steel bladder  pump  and the  tubing

bundles should  be performed as well.  Gloves should be worn at all times

during  pump assembly.   These activities should take approximately 35-45

minutes  and may  be  completed  at  a  location  central  to  all the  wells

which will  be sampled during the day.  At this point, the sample bottles

should  be checked for  proper  labelling.   Then the field  and sampling

logs  should be  readied for the next steps.   It  is  important to  record

the stagnant water  volume in the well from the  water  level reading and
                                   149

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 compare  it  to  that  calculated  for  the  well  from  the  evaluation of



 pimping requirements.





 Verification of  the Well  Purging Requirement




   .  Well purging requirements should be  calculated  from the hydraulic



 performance  of  the well  and  verified each  day by  measurement  of the



 well-purging parameters.   Let  us  presume  that the example well has been



 properly evaluated as  to  its  hydraulic  performance  by  the  methods



 described in the examples in Section  2.   In this  case,  the calculated



 purging requiement  is  approximately 80 L  (-4  well volumes) which should



 be purged prior  to  the collection  of representative samples.  Since the



 well  was  developed  at a flow rate of approximately 6 L/min, a conser-



 vative  pumping rate of 3 L/min has  been   chosen  for  purging  the well



 pumping rate of  1 L/min  has  been  chosen.   The pump is lowered to the



 point where  the  pump intake is at the top of the screened  interval.  It



 is  useful to  use  a "keeper"  which  consists  of a  wooden  or  plastic



 rectangle with holes drilled in it  to allow the gas  and  water  tubes  to



 slide through  and be held in place  with a  knotted cord or wire tie.  At



 this  time the  pump  should be started  and  adjusted to  produce  a  steady



 output-  through the  flow-through cell  and into  a collection bucket  or



 drum.  At  intervals equal to (10$  of the  calculated purging requirement



 (-8 L),  the  readings of  Eh, pH,  T, and n~1  are then  recorded and the



 cumulative volume pumped  (including that in the  cell)  should be  measured



and recorded.  When the calculated  purge volume  is  approached the  read-



ings should  be made at more frequent volume intervals and the  pump may



be slowed  to -1,000 mL/min.   When   the   readings  of  the well  purging



parameters have  stabilized to  within ±10$ over  two successive volume
                                  150

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increments (i.e.,  no less than 20% of the required purge  volume;  -16  L),
the pump  output may be considered equilibrated and sampling may  begin.
The data  in  Table 3.5 show the gradual  stabilization of the pH  and  JT1
values at -49 L which was  verified by pumping through  16   more  liters.
In this  example,  about 80$  of  the calculated well  purging requirement
was pumped prior to equilibration..
Sample Collection/Filtration
     Samples  should  be  taken  in a  prearranged  priority  so  that  all
sample  handling and  preservation takes place  as rapidly  as  possible.
Although  no  significant  error has been  reported  for  gas sensitive con-
stituents pumped  with a  positive  displacement  bladder device when air is
used  as  the drive  gas,  it may be prudent to  switch  the drive gas from
air  to N2 at this  point.   Samples for dissolved gases are  then taken,
in-line  ahead  of the flow-through  electrode  cell  at  a  flow  rate of
-100  mL/min.
      The samples  for dissolved gases,  volatile organic constituents, TOG
 and TOX are  taken by carefully slowing the delivery   rate   to  100 mL/min
 or less  and directing the flow to the  bottom  of  the  sample vessel (e.g.
 or by  flowing  into  a syringe  of appropriate  volume)'  and allowing the
 vessel .to, overflow at least  1.5  volumes.  The samples should  be rapidly
 capped,  excluding any  heads pace and  preserved  or  put  in the  sample
 cooler  as soon as  possible.   At this  point,  the time  (and  volume) of
 initial  sample collection should  be recorded.  An effort  should be  made
 to keep  track  of  the  cumulative volume pumped  during  sampling and all
 subsequent  steps.   Samples for 'extract-able organic  compounds and  total
 metals  can  then  be  collected.   In  filling  the large volume bottles the
                                    151

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 Table 3.5.
Quantity
 pumped
(liters)
    8
   16
   24
   32
   40
   49
   57
   65
Sample Purging Parameter Readings
                   Conductivity
      pH
     8.01
     7.67
     7.54
     7.19
     7.22
     7.16
     7.17
     7.16
580
625
623
622
619
620
621
620
       152

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flow rate can be increased but  should not  exceed the  pumping rate during
purging.
     At this point,  the pump discharge  is  connected to  an on-line filter
apparatus and  the samples  for  alkalinity,  dissolved  metals  and other
inorganic constituents  can be  collected  in priority order.   When   the
filtered  samples  have  been  collected,  the time  and cumulative  volume
pumped are recorded.  One member of the sampling team should oversee the
operation,  insure  proper  preservation of  the  samples,  and  make  the
entries  into the  field and sampling logs of  the  time  of  sample collec-
tion, double-checking the  labels on the storage vessels.  Another member
of  the  team should  begin titrating  alkalinity  samples,  at   least  in
duplicate.   The  titrations  should not be  delayed more than  two  hours
from  the initial  sampling time.   The other member of the  sampling team
should  be in charge of sample  collection,  time  and volume measurements
to insure that the samples and replicates are properly taken.   Then the
full  flow is redirected through the electrode cell.   Values of the well
 purging parameters should   be recorded after the cell has been flushed
 at least once, if volume permits.   These  values should later be compared
 to those taken just prior to the collection of  the initial samples to
 check on the stability of the  water during the time  of sampling.
      Now the  samples  and field  blanks should be  properly preserved and
 stored.   At least one replicate  of   each sample  (excluding  dissolved
 oxygen  and  alkalinity)  should be  spiked  with an  appropriate stock  solu-
 tion to  provide  a blind control standard for sensitive analytical  deter-
 minations.   To  insure good quality  control,  these   blind samples  are
                                   153

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  labelled  as  an extra  well and  placed in  the normal  sample handling



  scheme  enroute  to the laboratory.




      The  gas  supply to,  the pump  is then turned off, and  the  pump with



  the tubing bundle can be retrieved.  Before proceeding to the next well,



  the pump  should be  placed  in a graduated  cylinder  of  rinse or cleaning



  solution.  The  pump  should be   operated  to detect any leakage  and  to



  clean the pump  and  the  interior  surfaces of  the  sampling train. Any



 waste water that may be  contaminated with  hazardous  constituents  should



  be  managed in  a responsible manner.  Under  no circumstances  should  it



  be returned to the well.





 Field Determinations




      The  determination  of  alkalinity  dissolved oxygenand other  field



 constituents  (e.g. pH,  Eh,  T and a~1) should  be  completed at  this  point.



 Dissolved oxygen samples should be  kept  out of light, preserved and cold



 until  the  precipitate  has  formed  and  settled to  the  bottom  of the



 bottle.  After an hour or so, they should be shaken again and allowed to



 settle.   So long as  they are kept in the dark,  they can be held for 4-8



 hours  prior to acidification and titration.




     All other  field  parameters  can be  determined after  method cali-



 bration  has  been performed,  as  conditions  permit.    At  this time,  the



 field  and sampling  logs  should  be  checked   for  completeness  and  the



 initial  chain  of custody documentation has been completed.-




Sample Storage and Transport




     The procedures described in Section 2 should be  followed explicitly



from this point  until delivery to  the   laboratory.   Any unique circum-



stances  (e.g.  extreme  heat  or  cold,  delays  in  sample  handling,  etc.)
                                  154

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should be  recorded in the field   notebook.   It  is essential that  the




laboratory receive all  information which  may affect  analytical  pro-



cessing.   Notice of any extreme turbidity,  reactivity with the preserva-




tion  reagents,  etc.  should  be provided _in writing  to the  laboratory




personnel.



     These  sampling  procedures  are  sufficient  to  the  needs  of  most



ground-water  sampling programs.   If  unusual  conditions  exist,    they




should be  reported to the person in  charge of the  monitoring effort at



once.  This  will help prevent undue exposure of  sampling staff or water



samples  to conditions that may jeopardize  health or the  collection of




high  quality data.
                                   155

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                                 SECTION 4
                                CONCLUSIONS
      The  development of  reliable sampling  protocols for  ground-water

 quality  monitoring  is  a  complex,  programmatic  process  that must  be

 designed  to  meet  the   specific  goals  of  the  monitoring  effort  in

 question.   The  long-term goals and information needs of  the  monitoring

 program must first  be thoroughly understood.   Once  these  considerations

 have been  identified, the many  factors  that  can effect the  results  of

 chemical analyses from the monitoring program  can be addressed.

      In formulating the sampling  protocol,  the  emphasis  should be  to

 collect hydrologic  and  chemical  data that  accurately,represent in  situ

 hydrologic and chemical  conditions.  With good quality assurance  guide-

 lines  and  quality  control  measures,  the  protocol  should  provide the

 needed  data for  successful management of  the monitoring  program at a

 high level of  confidence.  Straightforward techniques that minimize the

 disturbance of  the subsurface  and  the  samples  at  each  step  in  the

 sampling effort should be given priority.

      The  planning  of  a  monitoring  program  should  be a  staged effort

 designed to  collect  information during the exploratory or initial stages

 of  the  program.    Information  gained  throughout the  development  of  the

 program  should be used  for  refining  the  preliminary program  design.

During  all  phases  of  protocol  development,   the long-term  costs  of

producing  the  required hydrologic and  chemical  data should be  kept  in

mind.  These long-term costs are several orders of magnitude larger than

the  combined costs  of  planning, well  construction, purchase  of sampling

and field equipment,  and data collection start-up.   it  also  should  be
                                  156

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remembered that high quality data cannot be obtained from  a  poorly  con-
ceived and implemented monitoring program, regardless of the added  care
and costs of sophisticated sampling and analytical procedures.
     Finally, the  ultimate  costs  of defending poor quality data  in the
legal arena or  in  compliance with regulatory  requirements  should  not be
overlooked.  The damage  to  the  credibility  of the program can be  sub-
stantial.
     Due  to the lack  of documented standard  techniques  for  developing
monitoring  programs,  constructing  monitoring  wells,  and  collecting
samples,  quality control measures must  be  tailored  for each individual
site  to be monitored.    They should be designed  to  insure that distur-
bances  to both the  hydrogeologic  system and  the sample  are minimized.
The care exercised in well placement  and  construction, and sample  col-
 lection and analysis can pay real dividends in the control of systematic
 errors.  Repeated  sampling and field measurements  will  further  define
 the magnitude  of  random errors  induced by  field  conditions  and  human
 error.   Still the  burden of assuring the success of a  program relies on
 careful  documentation  and the  performance of  quality assurance  audit
 procedures.
      The  hydrogeologic  conditions  at each  site must  be evaluated in
 terms  of the potential  impacts  the setting will have on  the design and
 effectiveness  of  the  developed  program.   Documentation of the  hydrology
 of the site  is essential at the planning stage, as well as during the
 operational life of the program.  Too little attention has been given to
 fully  understanding the environment  that is the  source of water col-
 lected from  monitoring  wells.   Only  after the  source'of water is known
                                    157

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 (delineation of  the vertical and horizontal  components  of  ground-water



 movement) can the effectiveness of the program be assured.




      The placement and construction of monitoring wells  can  be  among  the



 most  difficult  tasks  involved in  developing an  effective monitoring



 program.  The positioning  of  a monitoring point in a  contaminant flow



 path must be determined on the  basis  of hydrologic data to insure that



 the well is capable of monitoring  the  contaminant plume  or release.   The



 monitoring wells also  should be  constructed  using drilling techniques



 that avoid the  disturbance  of subsurface conditions due to the intro-



 duction of fluids  or  muds.   Monitoring wells should  be sized  both  to



 provide depth discrete hydrologic  and chemical data and to maximize the



 usefulness  of the  collected data.  The materials  selected for monitoring



 well construction should  be  durable  for the  intended  installation and



 minimize interference  with  the samples to be collected.   The wells also



 should be properly developed to maximize their hydraulic efficiency and



 minimize the  need to filter water samples.




     Sampling mechanisms  for  the collection  of ground-water  samples are



 among  the most error prone  elements  of monitoring programs.   Documenta-



 tion of  the field performance for most devices and materials  is  lacking.



Many of  the sampling designs may be expected to provide  adequate perfor-



mance  for conservative chemical constituents which are  not  affected  by



aeration, gas-exchange and degassing.  Testimonials of sampling  perfor-



mance based on the recovery of conservative,  unreactive  chemical  consti-



tuents are not reliable  for  planning effective monitoring efforts.   It



should be recognized that the purchase  of  a suitable sampler for  most
                                  158

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ground-water investigations is usually a very small  portion of  the  over-


all program cost.   It is further obvious that  the  choice of  the  right


sampler made of  appropriate materials will determine the  ultimate use- .


fulness of the chemical  data.   The recommended approach is to make the


choice of both samplers and materials on the basis of the most  sensitive


chemical  constituents  of   interest.    Typically,  reliable samples  for


dissolved  gases,  ferrous  iron and  volatile  organic compounds  are the


most difficult to collect and handle.

     The  information  needs  of  a ground-water  monitoring program  are
       t

determined by  the stated goals of the  program.   They should  be deter-


mined  by  the program manager,  and field and laboratory personnel during


the planning phase  of the project.   The  long-term  goals or anticipated


needs  of the  program also  should be  addressed at  the outset of the


program  to  insure data  consistency  and quality throughout the  life of


the program.

     The  definition of  a representative ground-water sample  will vary


from  site to  site  and perhaps from  sampling point  to  sampling  point,


depending on  the  situation under investigation.   Performance  criteria


for  the  achievement  of  representative  sampling   should include  the


accuracy, precision,  sensitivity  and completeness necessary to provide a


minimum level  of confidence in the data.   The  criteria  should  be  based


on both knowledge of the system to be measured  and  the experience  of the


project planning staff.   Close attention must be paid to the preliminary


investigation,  well  placement   and  construction,  hydrologic   data,


sampling frequency,  and  mobility and  persistence of  likely  chemical


 contaminants.    Natural  or man-induced  variability in  the hydrogeology
                                   159

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and  geocheraical characteristics of  the  site can only  be  distinguished



from each other by the interpretation of high quality sampling results.




It is  hoped that  by  the  careful implementation of  the recommendations



for sampling in this  guide,  that a level of  confidence in  ground-water



data  can be  established.    Our understanding  of  subsurface  processes



should improve in great measure as  reliable investigations  proceed.
                                 160

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                                SECTION  5

                             RECOMMENDATIONS



     Well drilling/completion, purging,  sampling and analysis steps  all

contribute to error in ground-water monitoring results.   The  procedures

must be, better understood as  they  effect  particular  classes of  contami-

nants.    This  information  is necessary  in order  to  facilitate    the

development of efficient protocols and QA/QC programs.   Specific problem

areas which require further research include:



     Drilling mud composition and effects on subsurface geochemistry.

     Grouting materials  and procedures which effectively seal  screened
     intervals  from leakage or  cross-contamination,  especially adverse
     effects of  contaminants on  grout set-up and integrity.

     Well development procedures which  are  effective  in reducing par-
     ti culate matter  in water samples.

     Efficient  methods  for  establishing  monitoring  points and sampling
     free-product or  non-aqueous contaminant phases  in  the subsurface.

     The  effects of  inadequate well-purging protocols  prior to sampling
      for  chemical  analysis, emphasizing  long term and  short  term well-
      casing material  effects on sample  integrity.

      Once the most critical  sources  of error  involved in specific con-

 taminant  monitoring  situations  have been identified, more basic studies

 of subsurface hydrogeology and  sample handling must be done to minimize

 sources  of systematic error and imprecision.  Research  is needed on:
      Filtration effects  on  ground-water samples  used  for transport  or
      contaminant  flux  investigations.     The  significance   of   total-
      recoverable  (i.e.,  non-filtered)'water  sample analytical  results
      for assessment work and colloidal transport effects require  further
      investigation.
                                   161

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     Methods  for the  interpretation of observed  contaminant  distribu-
     tions in creviced or fractured geological materials and the unsatu-
     rated zone need improvement.

     Improvements in  geophysical monitoring methods and  their  relation
     to more traditional contaminant detection methods  are needed.

     One area that  needs  particular attention is the training  of  field

and laboratory personnel in reliable monitoring techniques.  The scien-

tific literature on ground-water monitoring is developing rapidly.   All

monitoring personnel should make  an effort to acquaint themselves  with

published materials and maintain a  current understanding of  advances in

the field.
                                  162

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                               SECTION 5
                              REFERENCES
1.  U.S. Geological  Survey.   1977.   National Handbook of  Recommended
    Methods  for Water-Data  Acquisition.    USGS Office  of  Water  Data
    Coordination, Reston, Virginia.

2.  Wood, W. W.  1976.  Guidelines for Collection and Field  Analysis of
    Groundwater Samples  for  Selected  Unstable Constituents.   In:   U.S.
    Geological  Survey Techniques  for Water  Resources  Investigations,
    Book 1, Chapter D-2.

3.  Scalf,  M.  R.,   J.   F.  McNabb,  W. J.  Dunlap,  R.  L.  Cosby,  and
    J.  Fryberger.    1981.   Manual  of Ground-Water Quality  Sampling
    Procedures. National Water Well Association, Worthington,  Ohio.

4.  Brass, H. J., M. A. Feige, T. Halloran, J. W. Mellow,  D. Munch, and
    R.  F.   Thomas.    1977.    The National  Organic -Monitoring  Survey:
    Samplings   and  Analyses  for  Purgeable  Organic Compounds.    In;
    Drinking Water Quality Enhancement through Source Protection (R. B.
    Pojasek, ed.), Ann Arbor Science Publishers, Ann Arbor,  Michigan.

5.  Dunlap, W.  J.,  J.  F. McNabb, M.  R. Scalf, and R. L.  Cosby.   1977.
    Sampling   for   Organic   Chemicals   and   Microorganisms   in   the
    Subsurface.   Office  of    Research    and   Development,   USEPA,
    Robert S. Kerr Environmental Research Laboratory, Ada, Oklahoma.

6.  Sisk, S. W.  1981.   NEIC Manual for Groundwater/Subsurface Investi-
    gations  at Hazardous  Waste Sites.   USEPA  Office  of Enforcement,
    National Enforcement Investigations Center, Denver, Colorado.

7.  Fenn, D., E. Cocozza, J. Isbister, 0. Braids, B. Yare, and P. Roux.
    1977.   Procedures Manual for Ground Water Monitoring at Solid Waste
    Disposal Facilities.  EPA/530/SW611 , USEPA, Cincinnati,  Ohio.

8.  Tinlin,  R. M.,  ed.    1976.    Monitoring  Groundwater  Quality:
    Illustrative  Examples.    EPA  600/4-76-036,  USEPA,  Environmental
    Monitoring  and  Support  Laboratory, Office of Research and Develop-
    ment, Las Vegas,  Nevada.

9.  National   Council  of  the  Paper  Industry  for  Air  and  Stream
    Improvement.  1982.    A  -Guide  to  Groundwater Sampling.    Technical
    Bulletin  362, NCASI,  260 Madison  Avenue,  New York, New York.

10.  Todd, D.  K.,  R.  M.  Tinlin,  K.  D.  Schmidt,  and L. G. Everett.   1976.
    Monitoring    Ground-Water    Quality:       Monitoring   Methodology.
     EPA-600/4-76-026, USEPA, Las Vegas, Nevada.

11.   Gibb,  J.  P.,  R. M. Schuller, and R. A. Griffin.  1981.   Procedures
     for the  Collection  of  Representative  Water   Quality  Data   from
    Monitoring  Wells. Cooperative Groundwater Report 7, Illinois State
    Water   Survey  and  Illinois  State Geological   Survey,   Champaign,
     Illinois.
                                  163

-------
 12.  Grisak, G. E., R. E. Jackson, and J. F. Pickens.  1978.  Monitoring
     Groundwater  Quality:   The Technical Difficulties.   Water Resources
     Bulletin, June 12-14,  1978, San Francisco, Calif.,  p. 210-232.

 13.  Gillham, R.  W.,  M.  J.  L.  Robin,   J. F. Barker  and   J.  A.  Cherry.
     1983. Ground-Water Monitoring and Sample Bias.  Department of Earth
     Sciences, University of Waterloo.  Prepared for the American Petro-
     leum Institute.  API Pub. 4367, June 1983, 206 pp.

 14.  Brown, K. W. and S. L. Black.  1983.  Quality Assurance and Quality
     Control  Data Validation  Procedures Used  for  the  Love Canal  and
     Dallas Lead Soil Monitoring Programs.  Environmental Monitoring and
     Assessment 3, p. 113-122.

 15.  Nacht, S.  J.  1983.   Monitoring  Sampling Protocol  Considerations.
     Ground Water Monitoring Review, Summer, 1983, p. 23-29.

 16.  Keith,  S.  J.,  M.   T.  Frank,  G.  McCarty  and  G.  Massmah.    1983.
     Dealing With the Problem of Obtaining Accurate'Ground-Water  Quality
     Analytical Results.  In;   Proceedings of the 3rd National Symposium
     on  Aquifer  Restoration and  Ground  Water Monitoring.   May  25-27,
     1983, Columbus,  Ohio.   D. M.  Nielsen, ed.,  National Water  Well
     Association, Water  Well  Journal  Publishing Company,  Worthington,
     Ohio, 1983, 461  pp.

 17.  Kirchmer,  C.  J.    1983.    Quality  Control . in"  Water  Analyses.
     Environmental Science and Technology 17, 4,  p.r174A-181A.

 18.  Kirchmer, C. J.,  M. C.  Winter and  B.  A.  Kelly.   1983,   Factors
     Affecting  the  Accuracy   of   Quantitative   Analyses   of Priority
     Pollutants Using GC/MS.   Environmental Science and  Technology  17,
     396-401.                                                	

 19.  Dressman, R. C.  1982.   Elements  of a  Laboratory Quality Assurance
     Program.    Proc.  of  AWWA  Water  Quality  Technology  Conference,
     Nashville,  TN,  December   5-8.   American  Water  Works  Association,
     1982, p.  69-75.

20.  Dux, J.  P.    ,1983.   Quality Assurance in the  Analytical Laboratory.
     American Laboratory, July, 1983,  p.  54-63.

21.  Kingsley,  B.  A.   1982.  Quality Assurance in a  Control  Laboratory.
     Proc. of the AWWA  Water  Quality Technology Conference,  Nashville,
     TN,  December 5-8.  Journal American Water Works Association, 1982,
     p. 69-75.

22.  Kingsley,  B.  A.,  C. Gin,  W. R. Peifer,  D. F.  Stivers,  S. H.  Allen,
     H. J. Brass, E.  M. Glick  and  M.  J. Weisner.   1981.   Cooperative
     Quality  Assurance Program  for  Monitoring Contract  Laboratory Per-
     formance.    In:   Advances in  the Identification and  Analysis of
     Organic  Pollutants  in Water,  Chapter 45,  Vol. 2.  L. H.  Keith, ed.,
     Ann  Arbor Science,  Ann Arbor, MI,  1981.
                                  164

-------
23.  Barcelona,  M.  J.     1983.     Chemical   Problems   in   Ground-Water
     Monitoring  Programs.     in:     Proceedings   of  the   3rd  National
     Symposium  on  Aquifer  Restoration  and  Ground-Water Monitoring,
     Columbus, OH,  May  25-27, 1983,  p. 263-271.  D.  M.   Nielsen,  ed.,
     National  Water ' Well  Association, Water Well  Journal Publishing
     Company, Worthington,  OH, 461  pp.

24.  Taylor, J.  K.   1983.   Quality Assurance  of  Chemical  Measurements.
     Analytical Chemistry 53, 14,  p. 1588A-1593A.

25.  Taylor, J. K.  1981. .Validation of Analytical Methods. Analytical
     Chemistry 55, 6,  p. 600A-608A.

26.  ACS.    1980.   Guidelines  for  Data  Acquisition  and   Data  Quality
     Evaluation  in Environmental  Chemistry.    American  Chemical  Society
     Committee  on Environmental improvement,  Analytical   Chemistry  52,
     2242-2249.

27.  USEPA.  1982.  Test Methods for Evaluating Solid Waste, SW-846, 2nd
     edition.  Office of Solid Waste and Emergency Response, Washington,
     D.C. 20460, July.

28.  USEPA.   1979a.   Methods for  Chemical  Analysis of  Water and Wastes.
     EPA-600/4-79-020, USEPA-EMSL, Cincinnati, OH 45269, March.

29.  USEPA.   1979b.  Handbook  for Analytical Quality  Control  in Water
     and   Wastewater   Laboratories.     EPA-600/4-79-19,   USEPA-EMSL,
     Cincinnati, OH,  1979.

30.  Kratochvil,  B.  and  J.   K.  Taylor.   1981,.    Sampling for Chemical
     Analysis.   Analytical Chemistry  53, 8, 924A-938A.

31.  Claassen,  H. C.   1982.   Guidelines  and Techniques  for  Obtaining
     Water  Samples that Accurately Represent  the Water Chemistry of an
     Aquifer.   U.  S.  Geological  Survey, Open-file Report  82-1024, Lake,
     CO,  49 pp.       '

32.  Ingamells,  C. 0.   1974.  New  Approaches  to Geochemical Analysis and
     Sampling.   Talanta 21,  141-155.

33.  Ingamells,  C.  0.   and   P.  Switzer.    1973-   A  Proposed Sampling
     Constant  for Use in Geochemical  Analysis.  Talanta 20, 547-568.

34.  Keely, J. F.  1982.  Chemical Time-Series  Sampling.   Ground Water
     Monitoring Review,  29~37.

 35.  Keely, J.  F.  and  F.  Wolf.   1983-   Field Applications of Chemical
     Time-Series Sampling.   Ground Water Monitoring Review, 26-33.1

 36.  Hansen, E. A. and A. R. Harris.   1980.   An Improved  Technique for
      Spatial Sampling of Solutes  in Shallow  Ground Water Systems.   Water
      Resources Research 16,  4,  827-829.
                                   165

-------
 37.  Gillham, R. W.   1982.   Syringe Devices for Ground-Water Sampling.
      Ground Water Monitoring Review,  Spring 1982, 36-39.

 38.  Barvenik, M. J.  and R. M.  Cadwgan.    1983.   Multilevel Gas-Drive
      Sampling of Deep Fractured'Rock Aquifers  in Virginia.   Ground Water
      Monitoring Review,  Fall,  1983,  34-40.

 39.  McLaren, F. R.,  R.  Armstrong, G. M. Carlton.   1982.  Investigation
      and Characterization of  Large-scale  Ground  Water Contamination in
      Alluvial Aquifers.   Presented at Water Pollution Control Federation
      Conference, Oct.  3~8,  1982,  St.  Louis,  MO, 20 pp.

 HO.  Pankow,  J. F.,  L. M.  Isabelle,  J.  P. Hewetson, and  J. A.  Cherry.
      1984.  A  Syringe  and Cartridge  Method for Down Hole  Sampling for
      Trace  Organics in Ground Water.  Ground Water 22, 3, 330-339.

 41.  Eccles,  L. A. and R.  R.  Nicklen.   1978.  Factors  Influencing the
      Design  of  a  Ground  Water  Quality  Monitoring Network.    Water
      Resources  Bulletin,   Establishment   of  Water  Quality  Monitoring
      Programs.     American  Water  Resources  Association,  June  1978,
      196-209.                                       ;

 42.  Todd,  D. K.  1980.   Ground Water  Hydrology.   John  Wiley and Sons,
      N.Y.,  534 PP.

 43.   Nelson,  J. D. and R.  C.  Ward.   1981.   Statistical Considerations
      and Sampling Techniques for  Ground-Water Quality Monitoring. Ground
      Water  19,  6, 617-625.

 44.   Casey, D.,  P. N.  Nemetz and  D. H. Uyeno.  1983.   Sampling Frequency
      for  Water  Quality  Monitoring:  Measures  of  Effectiveness.    Water
      Resources  Research 19, 5, 1107-1110.                       •
45.
46.
47.
48.
49.
Cook,  J.  M. and D.  L. Miles.   1980.   Methods  for the   Chemical
Analysis  of Ground  Water.    Report  80/5, Institute of  Geological
Sciences,  Natural  Environment  Research  Council,  U.  K.  London,
55 pp.

APHA,  AWWA,  WPCF.   1980.  Standard Methods  for  the Examination of
Water   and   Wastewater,   15th  Edition,  American   Public   Health
Association,  American  Water  Works  Association,  and  the  Water
Pollution Control Federation.
Barcelona, M. J.  1984.
Water 22, 1, 18-24.
TOG Determinations in Ground Water.  Ground
Baker,  E.  L.,   P.  J.  Landrigan,   P.  E.  Bertozzi,  P.  H.  Field,
B. J. Basteyns and H.  G.  Skinner.   1978.  Phenol Poisoning  Due  to
Contaminated Drinking Water.  Arch. Env.  Health,  March/April, 1978,
89-94.

Elder,  V.  A.,  B.  L.  Proctor and R.  A.  Kites.    1981.   Organic
Compounds Found  Near  Dump Sites in  Niagara  Falls,  N.Y.   Environ.
Sci.  and Techn.  15,  10, 1237-1243.                          	
                                  166

-------
50.
51.


52.




53.



54.


55.


56.


57.




58.



 59.




 60.



 61.


 62.


 63-
Yare,  B.   S.     1975.    The  Use  of  a  Specialized  Drilling and
Ground-Water  Sampling  Technique  for  Delineation  of   Hexavalent
Chromium   Contamination  in   an   Unconfined   Aquifer,   Southern
New Jersey Coastal Plain.  Ground Water  13,  2,  151-15**.

Seanor, A. M. and Brannaka.   1983.   Efficient  Sampling  Techniques.
Ground Water Age, April, 41-46.

Barcelona,' M. J.,  J.  P. Gibb and R. A.  Miller.   1983.   A Guide  to
the  Selection of Materials  for Monitoring  Well  Construction  and
Ground-Water Sampling.  Illinois State Water Survey Contract Report
#327; USEPA-RSKERL, EPA-600/52-84-024, 78 pp.

Barcelona,  M. J.,  J.  A. Helfrich,  E.  E. Garske  and J.  P.  Gibb.
1984.  A Laboratory Evaluation of Ground Water Sampling Mechanisms.
Ground Water Monitoring Review 4, 2, 32-41.

Johnson, E. E;,  Inc.   1966.   Ground Water and  Wells, St. Paul,  MN.
pp.  440.

Richard,  M.  R.   1979.   The  Organic Drilling  Fluid Controversy,
Part I.  Water'Well Journal, April, pp.  66-74.

Richard,  M.  R.   1979.   The  Organic Drilling  Fluid Controversy,
Part II.   Water  Well  Journal, May,  pp. 50-58.

Brobst,  R. B."   1984. • Effects  of  Two Selected  Drilling Fluids on
Ground Water•Sample  Chemistry.   Monitoring Wells,  Their Place in
the Water Well  Industry Educational Session, NWWA National Meeting
and Exposition,  Las Vegas, NV, September  1984.

Villaume,  J.  F.  1985.   Investigations  at  Sites  Contaminated with
Dense,  Non-Aqueous Phase Liquids  (NAPLS).   Ground Water Monitoring
Review 5(2),  60-74.

Walker,  S. E,   1983.  Background  Ground-Water Quality  Monitoring:
 Well Installation Trauma.   In:   Proceedings  of  the Third National
 Symposium  on  Aquifer  Restoration  and Ground-Water   Monitoring,
 May 25-27, NWWA Fawcett Center,  Columbus, OH  1983,  p.  235-246.

 Strausberg,  S.   1983.   Turbidity Interferences  with  Accuracy  in
 Heavy  Metals   Concentration.     Industrial  Wastes,   March/April,
 pp. 20-21.

 Saines, M.   1981.   Errors in Interpretation  of  Ground-Water Level
 Data.  Ground Water Monitoring Review 1(1),  56-61.

 Freeze, A. R. and J.  A. Cherry.   1979.   Groundwater. Prentice-Hall,
 Inc., Englewood Cliffs, New Jersey.

 Prosser,  D.  W.   1981.   A Method  of Performing Response  Tests  on
 Highly Permeable Aquifers.  Ground Water, Vol. 19, No.  6.
                                   167

-------
 64.  Hvorslev,  M.  J.     1951.    Time  Lag  and  Soil  Permeability in
      Groundwater Observations.  U.S.  Army  Corps of Engineers Waterways
      Experiment Station Bulletin 36,  Vicksburg,  Virginia.

 65.  Cooper, H.  H.,  J.  D. Broedehoeft,  and I.  S.  Papadopulos.   1967.
      Response of  a Finite-diameter  Well to  an  Instantaneous Charge of
      Water.  Water Resources  Research,  No.  3,  pp.  263-269.

 66.  Theis, C.  V.    1955.   The Relation  Between the  Lowering  of  the
      Piezometric Surface  and the Rate  and Duration of Discharge  of  a
      Well Using Groundwater Storage.   Trans.  American  Geophysical Union,
      16,518-524.	
 67.


 68.


 69.



 70.



 71.



 72.



 73.
74.
75.
76.
 Jacob,  D.  E.   1950.   Flow of  Ground Water.   Engineering Hydraulics,
 edited by H.  Rouse,  John Wiley and Sons, New York.

 Papadopulos,  I. S.,  and H.  Cooper.   1967.  Drawdown  in  a Well of
 Large Diameter. Water Resources  Research, 3( 1):24l-244.

 Faust,  C.  R.  and J. W. Mercer.   Evaluation  of Slug Tests in Wells
 Containing a Finite Thickness  Skin.   Water  Resources  Research 20.
 4,  504-506.                            	

 Stallman,  R.  W.  1956.   Numerical  Analysis of Regional Water Levels
 to  Define  Aquifer Hydrology  Transactions.    American Geophysical
 Union 37,  4,  451-460.                          	~~	~	

 Holden,  P. W.   1984.   Primer  on  Well  Water Sampling  for Volatile
 Organic Compounds.  University  of  Arizona, Water Resources Research
 Center, Tucson, AZ, 44 pp.

 Ho,  J.  S-Y.   1983.    Effect  of Sampling Variables  on Recovery of
 Volatile   Organics  in  Water.    Journal   American  Water  Works
 Association,  December  1983, 583-586.

 Korte, N.  and P. Kearl.   1984.  Procedures  for  the Collection and
 Preservation  of Ground Water  and  Surface Water Samples and for the
 Installation   of   Monitoring  Wells.    Bendix  Field   Engineering
 Corporation.    Prepared   for    U.S.    Department   of    Energy
 #DE84007264-GJ/TMC-8.  January, 1984,  58pp.
Armstrong, R.  and F. R. McLaren.   1984.
Catcher in Ground Water Quality  Sampling.
Review, Fall 1984, p. 48-53.
                                                The Suction Side  Sample
                                                Ground  Water  Monitoring
Cherry, J.  A.,  R. W. Gillham,  E.  G. Anderson, and P. E.  Johnson.
1983.  Migration  of  Contaminants at a  Landfill:  A Case Study,  2.
Ground Water Monitoring Devices.  Journal Hydrology 63, 31-49.

Barcelona, M.  J., J.  A.  Helfrich,  and E.  E. Garske.    Sampling
Tubing Effects  on Ground  Water Samples.  Analytical Chemistry 57,
2, 460-464.        '                        	 	~
                                  168

-------
77.
78.
79.
80.
 81
 82.
 83.
 84,
 85.
 86.
 87.
Gdrvis, D.  G.  and D. H.  Stuermer.   1980.   A  Weil-Head Instrument
for Multi-Parameter Measurement During Well  Water  Sampling.   Water
Research 14, 1525-1527.

Garske, E. E. and M. R.  Schock.  1985.   An Inexpensive Flow-Through
Cell  and  Measurement  System  for  Monitoring  Selected  Chemical
Parameters  in  Ground Water  (In Press).   Ground  Water Monitoring
Review.

Levine,  S.   P.,  M.  A.  Puskar, P.  P.  Dymerski, B.  J.  Warner  and
C.S.Friedman.  1983. Cross-Contamination of Water  Samples Taken for
Analysis-of  Purgeable Organic Compounds.  Environmental Science and
Technology  17, 2", 125-127.

Skougstad,  M.; W.   and  G.  F.   Scarbo,  Jr.    1968.    Water  Sample
Filtration   Unit.    Environmental  Science  and Technology   2,  4,
298-301 .

Kennedy,  V.  C.,   E.   A.   Jenne,   and  J.  M.  Burchard.    1976.
Backflushing Filters for Field Processing 'of Water Samples Prior to
Trace-Element  Analysis.   U.S.G.S.  Water Resources Investigations,
Open-File Report 76-126.

Kennedy,  V. C., G.  W.  Zellweger and  B.  F.  Jones.   1974.    Filter
Pore Size Effects  on the Analysis of Al, Fe,  Mn,  and Ti in Water.
Water Resources  Research  10, 4, 785-790.

Silva,  R.  J.  and  A.  W.  Yee.    1982.    Geochemical  Assessment of
Nuclear Waste Isolation:  Topical Report -  Testing  of Methods for
the Separation  of  Solid  and   Aqueous  Phases.   Lawrence Berkeley
Laboratory Report  #LBL-14696,  UC-70.

Korte, N.  and D.  Ealey.    1983.    Procedures  for  Field Chemical
 Analyses of Water  Samples.    Technical  Measurements Center,  U.S.
Department  of Energy,  Grand  Junction  Area  Office,  GJ/TMC-07(83),
UC-70A, 48 pp.

 Schock, M.  R.  and S.  C. Schock.  1982.   Effect of  Container  Type on
 pH and Alkalinity Stability.  Water Research 16, 10,•1455-1464.

 Ligon, W.  V.  and  H.  Grade.   1981.   PolyCethylene  glycol) as  a
 DiluenT" for  Preparation of   Standards  for  Volatile Organics  in
 Water.  Analytical Chemistry 53,  920-921.

 Stolzenburg, T. R.  and D. G.  Nichols.   1985.   Preliminary  Results
 on  Chemical  Changes  in  Ground .  WAter  Samples  Due  to  Sampling
 Devices.   report  to Electric  Power Research  Institute,  Palo Alto,
 CA,  EA-4118 by  Residuals Management  Technology, Inc., Madison, WI,
 June.
                                    169
                                           «U.S.GOVERNMENTPRDmNCOmCE:1992-6'»8. 003^.07. 3

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