EPA-680/4-73-001-5
                                              February 1974
          ENVIRONMENTAL RADIOACTIVITY

  LABORATORY  INTERCOMPARISON STUDIES  PROGRAM

                   1973 - 1974
                       by

           Quality  Assurance Branch
         Technical  Support Laboratory
    National Environmental Research  Center
               Las  Vegas, Nevada
               ROAP  Number 22ADB
            Program  Element 1HA327
    NATIONAL ENVIRONMENTAL RESEARCH CENTER
      OFFICE OF RESEARCH  AND DEVELOPMENT
     U.S.  ENVIRONMENTAL  PROTECTION AGENCY
           LAS VEGAS,  NEVADA  89114
For sale by the Superintendent of Documents, U.S'. froVernment Printing Office, Washington, D.C. 20402 - Price 65 ewits

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                           PREFACE
     Quality assurance is an integral part of any viable environ-
mental monitoring activity.  The primary goals of the Environmental
Protection Agency's (EPA) quality assurance program are to improve
and document the credibility of environmental measurements.  To
achieve these goals, quality assurance is needed in nearly all  seg-
ments of monitoring activities and should cover personnel, methods
selection, equipment, and data handling procedures.

     Five major functions, each essential to an effective quality
assurance effort, comprise EPA's quality assurance program:

            •  Promulgation of standardized methods of
               measurement

            •  Distribution of standard reference materials

            •  Issuance of guidelines and procedures

            •  Training and technical assistance

            •  Evaluation and certification of monitoring
               activities

     This manual has been prepared to assist laboratories involved
with environmental radiation measurements in developing and maintain-
ing a quality control program and documenting the precision and
accuracy of their data.  All EPA monitoring programs are requested
to make use of this document in planning their own radiation measure-
ments and in assisting the States in carrying out radiation monitoring
activities.

     Comments concerning the utility of this document, along with any
suggestions for possible changes and revisions, are welcomed.  Questic
on matters related to quality assurance of environmental measurements
in various field should be directed to the following person(s):

               Air Pollution

                 Mr. Seymour Hochheiser, Chief
                 Quality Control Branch
                 Quality Assurance and Environmental
                   Monitoring Laboratory
                 National Environmental Research Center
                 Research Triangle Park, North Carolina  27711
                              ii

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               Hater

                 Mr. Dwight Ballinger, Director
                 Methods Development and Quality Assurance
                   Research Laboratory
                 National Environmental Research Center
                 Cincinnati, Ohio  45268

               Pesticides

                 Dr. M. T. Shafik, Acting Chief
                 Chemistry Branch
                 Primate and Pesticides Effects Laboratory
                 National Environmental Research Center
                 Research Triangle Park, North Carolina  27711

               Radiation

                 Mr. Arthur N. Jarvis, Chief
                 Quality Assurance Branch
                 National Environmental Research Center
                 Las Vegas, Nevada  89114

      During the months ahead, manuals and docoments will be issued
which provide guidelines to be followed in all phases of monitoring
activities—sampling, analysis, and data handling—and in all media;
air, water, and land.  Use of these guidelines throughout the Agency
will enable a uniform approach to be established within EPA which
ultimately can be implemented at the State level.   This should permit
a significant improvement in the validity and reliability of environ-
mental data which the Nation collects.

      The implementation of a total and meaningful  national  environ-
mental quality assurance effort cannot succeed without the full
support of all monitoring programs.  Your cooperation is appreciated.
                                 ill

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                TABLE OF CONTENTS
Preface   ----------____    -j
I.
II.
III.
IV.

\/
i au i c \j i ounuciiu- -- - _____
The Laboratory Intercomparison Studies Program
Types of Environmental Samples Distributed - -
final \/c-ic n-f Hata _ - _ -

Participation in the Laboratory Intercomparison



- lit
1
- 3
7


14

1C
Request Forms
                        IV

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I.     THE LABORATORY INTERCOMPARISON STUDIES PROGRAM

       Environmental measurements for radiation are made daily by
many different Federal, State, local and private agencies.  The data
from these measurements are used for a wide variety of purposes,
including health effects, the establishment of standards and guides,
and for enforcement activities.  It is therefore imperative that
the precision and accuracy of the data be assured in order that
policy decisions concerning environmental quality are based upon
valid and comparable data.

       In order to attain this goal, an Agency-wide quality assur-
ance program has been implemented within the U.S. Environmental
Protection Agency (EPA).  In the area of radiation, quality control
responsibilities have been assigned to the Quality Assurance Branch
at the EPA's National Environmental Research Center-Las Vegas which
carries out a program designed to encourage the development and
implementation of quality control laboratory procedures for sample
collection, analysis, data handling, and reporting purposes.

       A major objective of this program is to assist laboratories
involved in environmental radiation measurements to develop and main-
tain both an intralaboratory and an inter!aboratory quality control
program.  In part, this is accomplished through an extensive labora-
tory intercomparison study ("cross-check") program involving environ-
mental media (milk, water, air, food, soil and gases) and a variety
of radionuclides with activities at or near environmental levels.

       A number of different environmental samples, containing pre-
cisely known amounts of one or more radionuclides, are prepared and
routinely distributed to all laboratories requesting them.  These
laboratories perform the required analyses and return their data to

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the Quality Assurance Branch for statistical  analysis and  compari-
son with other participating laboratories.   A computer report and
a continually updated performance chart are returned to each par-
ticipant.  The program thus enables a laboratory to document the
precision and,accuracy of radiation data, identify instrumental
and procedural problems, and to compare performance with other
laboratories.

       Each laboratory participating in a cross-check study is ex-
pected to have an internal  quality control  program in operation  to
insure that all instrumentation is calibrated and functioning and
that analytical procedures  are being carried out properly.   Such  a
program includes continual  monitoring of instrumentation,  the plot-
ting of instrument control  charts, frequent analysis of replicate
samples to check precision, and the regular measurement of samples
to which known amounts of activity have been added, to check the
accuracy of systems.

       Participation in a laboratory intercomparison does  not auto-
matically guarantee the precision and accuracy of a laboratory's
data and should not be considered as a substitute for a continuous
quality control program within a laboratory.  However, intercom-
parison data may be useful  either for indicating previously unsus-
pected instrumental problems or procedural  deficiencies, or for
documenting the precision,  accuracy and validity of a laboratory's
work.  Participation in a laboratory intercomparison study program
thus serves as a check on the' internal quality control program.

       If your laboratory does not now participate in the  cross-
check activities of the Quality Assurance Branch at the NERC-LV,
or if you wish to expand its participation, you are encouraged to
do so.

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II.    TYPES OF ENVIRONMENTAL SAMPLES  DISTRIBUTED

       The current laboratory intercomparison  studies  program  in-
volves the analysis of a  variety of media  containing environmental,
or near environmental, levels of radioactivity.  These include:

       MILK
       Four-liter milk samples containing  40K,  89Sr, 90Sr,  131I,
       137Cs, and 140Ba are distributed  on a monthly basis.

       WATER
       Water containing several  different  mixtures  of  radioactive
       materials are included in the cross-check program.

           Four-liter samples for the  analysis  of gross alpha
           and gross beta analysis are sent to  participating
           laboratories every other month.

           Four-liter samples containing 51Cr,  63Zn, 60Co,
           106Ru, 134Cs,  and 137Cs for gamma analysis  are
           distributed every other month.

           Sixty-milliliter samples for  tritium analysis, are
           mailed on a monthly basis.

           Four-liter water samples containing  239Pu are
           shipped to laboratories during  May and November
           of each year.

           Four-liter samples of well  water containing 226Ra
           are distributed  in November,  January, May and July.

-------
       AIR
       Air filters,  with  optional  2-inch or 4-inch
       diameters,  are  sent  out  on  a  quarterly  basis  for
       gross  alpha,  gross beta, and  239Pu  analysis.

       SOIL
       One-hundred-gram soil  samples,  containing  239Pu,
       will  be distributed  twice each  year beginning in
       December 1973.

       FOOD
       Three  4-liter food slurries containing  89Sr,  90Sr,
       131I,  137Cs,  140Ba,  and  K are sent  to participants
       once each quarter.

       URINE
       Urine  samples (60  ml)  containing tritium are
       shipped on a  quarterly basis.

       GASES
       Cylinders containing either 85Kr or 133Xe  are dis-
       tributed twice each year.

       Sample size,  activity levels, type  of analysis,  and other
pertinent information concerning the cross-check  samples are summa-
rized in Table 1.  The distribution  schedule is outlined in Table 2,

       A laboratory  may participate  in as  few  or  as  many of the
studies as it desires.

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III.   ANALYSIS OF DATA

       Each participating laboratory is expected to carry out three
independent determinations for each radionuclide included in a par-
ticular cross-check and to report its results on a form (Figure 1)
provided with the sample.

       Upon receipt of the reports from all participating labora-
tories, the data are transferred to punch cards and introduced into
a CDC 6400 computer for analysis.  As indicated in the sample cal-
culations (Appendix I), this analysis includes determination of the
experimental standard deviation, calculation of the normalized
range, normalized deviation, experimental error, and the grand
average of all laboratories.  The expected analytical  precision
values used as a basis for judging laboratory performance for spe-
cific nuclides are summarized in Table 3.

       A report is generated containing the data reported by all
participating laboratories, listed according to their identity code,
along with the results of the computer analysis (Table 4, Figure  2).
In addition., a control chart is generated and reproduced for each
radionuclide included in the sample (Figures 3 and 4).  The control
charts are updated each time a laboratory participates in a par-
ticular cross-check study, thus giving each laboratory a continuous
record of its performance.

       A copy of the computer printout and a control chart for each
radionuclide is mailed to each participant approximately 2 weeks
following the report due date.

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          \      U.S. ENVIRONMENTAL PROTECTION AGENCY
g ^^f^7  $     NATIONAL ENVIRONMENTAL RESEARCH CENTER
\^**^g                   LAS VEGAS, NEVADA
  % *X
                               QUALITY ASSURANCE BRANCH


          Laboratory	ID

          Contact Person                            Phone
          Sample Type 	Tritium in Water
          Collection Date         8-10-73    0400 PST
                         Analysis  #1

                         Analysis  #2

                         Analysis  #3
                    NOTE:   All results  are  in pCi/1 with background
                           subtracted.  Total activity is less than
                           3500 pCi/1  3H.
          Please send your results  no  later  than   September 17, 1973*   to:

                        U.S.  Environmental Protection Agency
                        National  Environmental Research Center
                        Quality Assurance Branch
                        P.O.  Box  15027
                        Las Vegas,  NV   89114

          *Results not received by  this date will  not be included in final report,
                     Figure 1.   Results  reporting form

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                               Table 3
                         Laboratory Precision
                     One Standard Deviation Values
                         For Various Analyses
Nuclide
 131
 137Cs


  89Sr


  9°Sr


    K

    Ca

Gross Alpha

Gross Beta



   3H


 226Ra

 239Pu
         Level

  5 to 100 pCi/1 or Kg
> 100 pCi/1 or Kg

  5 to 100 pCi/1 or Kg
> 100 pCi/1 or Kg

  5 to 100 pCi/1 or Kg
> 100 pCi/1 or Kg

  5 to 100 pCi/1 or Kg
> 100 pCi/1 or Kg

  2 to 30 pCi/1 or Kg
> 30 pCi/1 or Kg

>_ 0.1 g/1 or Kg

>_ 0.1 g/1 or Kg

>_ 1 pCi/1

  1 to 25 pCi/1
> 25 to 130 pCi/1
> 130

< 4000 pCi/1
> 4000 pCi/1

>_ 0.1 pCi/1
 Standard Deviation
Single Determination

5 pCi/1
5%

5 pCi/1
5%

5 pCi/1
5%

5 pCi/1
5%

1.5 pCi/1
5%

0.06 g/1

0.02 g/1 or Kg

25%

25%
6.5 pCi/1
5%

% Is = 16985x(pCi/l)--9067
10%

15%
      pCi/1, gram or sample  10%

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Title:
Column 1:,

Column 2:

Column 3:

Columns 4
  & 5:
Program name, sample collection date, sample code
letter, analysis type, known concentration of radio-
nuclide, expected standard deviation of analysis -
single determination.

Laboratory identification code (A, B, C, etc.).

Laboratory results (0-25 results listed down column) .

1 s (standard deviation) of the experimental results.

Normalized Range Value in "Mean Range + Standard Error
of the Range" (R + OR) units for comparability.  (See
Statistical Techniques for Quality Control of Environ-
mental Radioassay, AQCS Report Stat-1, November 1964,
pp 4-8) (SR = OR for printing purposes).
Column 6 :    Average Value.

Column 7 :    Normalized Deviation from the Grand Average Value of
             all laboratories expressed in a^ units.

Column 8:    Normalized Deviation from the Known Value expressed in
             cfy units.

Bottom of    Is experimental error of all laboratories and the
Chart:       Grand Average of all laboratories.
  Figure 2.  Explanation of terms used in participant date report
                              10

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        Table 4.   SAMPLE ANALYSIS AND  REPORT OF PARTICIPANT'S DATA
NFRC-LV TRlTlL.  IN '.«!ATPR CROSSCHECK PROGR'


                12/27/72        SA"PLE - A


                                  1579.00  +/-


                                        S
LAB
0
0
0
p
D
p
4G
AG
AG
AH
AM
AH
AI
AI
AI
1500.0
1400.0
1^00.0
187?. 0
1688.0
1596.0
1^30.0
1810.0
1740.0
1626.0
1477.0
16b?.0
2011.0
1713.0
2473.0
                      SIGMA
                      57.74
                     140.53
                      47.26
                      94.43
                     382.94
          MO OATA
R  +
       R
.18 + 0
.49 + 0
.16 + 0
.31 + 0
1  +  .41
  PCI/L

 NORMALIZEO DEVIATION

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Title:
Name of Program, Laboratory Code Letter, and Type
of Analysis.
Upper Graph:
"Normalized Deviation from Known versus the Month
of Analysis."  (The 95.0% (y ± 2oM) and the 99.7%
(p ± 30^) Confidence Levels were chosen as the
Warning Levels and Control Limits respectively.)
Middle Graph:
"Normalized Deviation from the Grand Average Value
of All Laboratories versus the Month of Analysis."
(The 95.0% (x ± 2aM) and the 99.7% (x ± 3aM)
Confidence Levels were chosen as the Warning Levels
and Control Limits respectively.)
Lower Graph:
"Normalized Range Values_(R + OR) versus the_Month of
Analysis."  (The 97.5% (R + 2oR) and -100% (R + 3oR)
Confidence Levels were chosen as the Warning Levels
and Control Limits respectively.)
      Figure 3.   Explanation of terms used in the control  chart
                              12

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      TRITIUM IN WATER CROSS CHECK PROGRAM
           LAB-D                   3H
        NORMALIZED DEVIATION FROM KNOWN
4
3
2
| o



4
3
2
5
(D 0



1971



X N A -'
V V


1972

.
' \ A^ f^^**\
v \/ \^



CL
WL
WL
PI

JFMAMJJASONDJFMAMJJASOND
NORMALIZED DEVIATION FROM GRAND AVERAGE
1971


•— «,

Y


1972


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v^ ^N^
>


CL
WL
WL
CL
JFMAMJJASONDJFMAMJJASOND
NORMALIZED RANGE

R + 3
R + 2
R + 1
T O
1971



. • _ . . • • 1 1 1 .
1972



1 i. .1.1 1 • _ • .
CL
WL
JFMAMJJASONDJFMAMJJASOND
           Figure 4.   Control chart
                     13

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IV.    PARTICIPATION IN THE LABORATORY INTERCOMPARISON STUDIES
       PROGRAM
       Any laboratory involved in,  or concerned with,  environmental
radiation monitoring and surveillance, is eligible to  participate
in any one or all  of the cross-checks described.   Moreover,  depend-
ent upon personnel  available and their workload,  a laboratory may
elect to receive samples on a less  frequent basis than indicated  on
the distribution schedule (Table 2).

       To become a participant in the laboratory intercomparison
studies program, complete one of the  forms included in this  publi-
cation and return to:
              U.S.  Environmental  Protection Agency
              National  Environmental  Research Center
              Quality Assurance Branch
              P.O.  Box 15027
              Las Vegas, NV  89114
       Should the laboratory require additional  types of cross-check
samples at some later date, a second form—indicating the samples
desired—should be submitted.
                              14

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V.  APPENDIX
                    Statistical Calculations

     To illustrate the computations performed by computer, sample calcu-
lations are given using data for three hypothetical samples analyzed at
one laboratory.
     First, the analytical results are listed and the mean (sample calcu-
lation a) and the standard deviation (sample calculation b) are computed.
These statistics provide measures of the central tendency and dispersion
of the data.  In our example the mean,  X , equals 60 pCi/1 and the
standard deviation,  S , equals 10 pCi/1-
     Next, the normalized range (sample calculation c) is computed by
first finding the mean range,  R , the control limit,  CL , and the
standard error of the range,  OR .  The normalized range measures the
dispersion of the data (precision) in such a form that control charts
may be used.  Control charts allow one to readily compare past analytical
performance with present performance.  In the example, the normalized
range equals  1R + 2.600R  which falls between the upper warning level,
R~ + 2oD , and the upper control limit,  R + 3on .  The precision of the
      K                                       K
results may be suspect.
     The normalized deviation is calculated (sample calculation d) by
computing the deviation and the standard error of the mean,  a  .  The
normalized deviation allows one to readily measure central tendency
(accuracy) through the use of control charts.  Trends in analytical
accuracy can be determined in this manner.  For this example, the
normalized deviation is +0.693 which falls between the upper and lower
warning levels.  The accuracy of the data is acceptable.
     Finally, the experimental error of all  laboratories, the grand
average, and the normalized deviation from the grand average are
calculated in order to ascertain the performance of all  the laboratories
as a group.  Any bias in methodology or instrumentation may be found
from these results.  Since the results of only one laboratory are listed
in the Appendix, the equations are shown without any sample calculations.
                                15

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                    Sample Calculations












a.  Analysis Data:




    Known value  =   62 pCi/1




    Standard deviation (single determination)   =  5  pCi/1
Sample No.
1
2
3
Activity pCi/1
50
60
70
                                          Number of  samples  (N)   =  3
                       x.   =  180 pCi/1




                       X   =   60 pCi/1
b.  Experimental Standard Deviation    (S)
                         (I
    S  =
                      N - 1
    S  =
                              I50L+60
    S  =  10 pCi/1
                              16

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c.  Calculation of Normalized Range

    Step 1.   Mean Range  (R)

              R = 6-20               Where d2 = Central line factor*

              R = (1.693)(5 pCi/1)        d2 = 1.693* for N = 3

              R = 8.465 pCi/1              a = Standard deviation
                                               (single determination)


    Step 2.   Control Limit (CL)

              CL = R + 3aR          Where D^ = Control Limit factor*

                 = Diji                    Dk = 2.575

                 = (2.575)(8.465 pCi/1)

                 = 21.797 pCi/1


    Step 3.   Standard Error of the Range (OR)

              aR = 1/3 (R + 3oR - R)

                 = 1/3 (D^R - R)

                 = 21.797 pCi/1 - 8.465 pCi/1
                               3

                 = 4.444 pCi/1
* Rosenstein, M. and A. S. Goldin, Statistical Techniques for
  Quality Control of Environmental Radioassay, AQCS Report Stat-1.
  U.S. Department of Health, Education and Welfare, PHS, Nov. 1964
                              17

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    Step 4.   Normalized Range  (Range expressed in terms of R and OR)

              Where w = # of R and x = # of OR defining R

              If R > R let w = 1 and solve for x

              If R <_ R let x = 0 and solve for w

                   Since, in this example, R > R  (i.e., 20 > 8.465)
                   let w = 1 and solve for x

              R = wR + xaR

                  R - wR
              x = 	
                    °R

                  20 - (1)(8.465)
              x        4.444

              x = 2.598
     Normalized Range = 1R + 2.598aR
d.   Calculation of the Normalized Deviation

    1.   Deviation = True Value - X

                   = 62 pCi/1 - 60 pCi/1

                   = 2 pCi/1
                              18

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    2.   Standard Error of the Mean   (am)
         Jm    , „
              V N
            _ 5 pCi/1
         °m =
                 3



         am = 2.887 pCi/1
    „    XT    i •   j rv           Deviation
    3.   Normalized Deviation = 	
                                  2 pCi/1
                                2.887 pCi/1



                              = 0.693
e.  Experimental Error =       (x.2) -  ^ Xi)
        (All labs)                        N
                                    N-l
         Where x-^ are the "1, 2, 3, ...i" results and N equals  the

         number of results in the calculation.
f .   Grand Average = — ri— where x^ and N are defined as  in  "e"  above.






g.   The Normalized Deviation from the Grand Average is  calculated  as

    in "d" except the Grand Average value is used instead  of the

    Known Value.
                              19

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing)
  W-T6§8/4-73-001-b
                                                           3. RECIPIENT'S ACCESSION-NO.
|4. TITLE ANDSUBTITLE
 Environmental Radioactivity Laboratory Intercomparison
 Studies  Program, 1973-1974
               REPORT. DATE      .            .
               December 1973  (preparation)
             6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
  Quality  Assurance Branch
  Technical  Support Laboratory
                                                           8. PERFORMING ORGANIZATION REPORT NO.
                   n/a
Ig. PERFORMING ORGANIZATION NAME AND ADDRESS
  National  Environmental  Research Center
  U.S.  Environmental Protection  Agency
  P.  0.  Box 15027
  Las Vegas, NV  89114
                                                           10. PROGRAM ELEMENT NO.
                    1HA327
             11. CONTRACT/GRANT NO.
                   in-house report
12. SPONSORING AGENCY NAME AND ADDRESS
  Office  of  Research and Development
  U.S.  Environmental Protection  Agency
  Washington,  DC  20460
             13. TYPE OF REPORT AND PERIOD COVERED

               interim (]973-19741	
             14. SPONSORING AGENCY CO6E
15. SUPPLEMENTARY NOTES
16. ABSTRACT
  The U.S.  Environmental Protection  Agency's intercomparison studies program  for
  laboratories  involved in environmental  radiation measurements is described.   The
  types of  environmental samples  distributed, the analysis  required for each  sample,
  the distribution schedule, and  the statistical analysis anci reporting of results
  are discussed.   Instructions and application forms are  included for laboratories
  desiring  to participate in the  program.

  This document  is not a research report.   It is designed for use by laboratories
  participating  or desiring to participate in this quality  assurance program.
17.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                              b.lDENTIFIERS/OPEN ENDED TERMS
                           c. COSATI Field/Group
  quality assurance
  quality control
  quantitative analysis
  radioactivity
  statistical quality  control
                             07 05/14 04
13. DISTRIBUTION STATEMENT
  Release  unlimited
     (NERC-LV, NTIS)
19. SECURITY CLASS (ThisReport)
  Unclassified
                                                                         21. NO. OF PAGES
20. SECURITY CLASS (Thispage)
  Unclassified
                           22. PRICE
EPA Form 2220-1 (9-73)

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                                                          INSTRUCTIONS

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EPA Form 2220-1 (9-73) (Reverse)

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