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     INDOOR RADIATION EXPOSURE

        DUE TO RADIUM-226 IN

      FLORIDA PHOSPHATE LANDS
      Richard J. Guimond
      William H. Ellett, Ph.D.
      Joseph E. Fitzgerald, Jr.
      Samuel T. Windham
      Philip A. Cuny
          Revised Printing

             July 1979

  Criteria and Standards Division
    Office of Radiation Programs
U.S. Environmental Protection Agency
       Washington, D.C. 20460

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                                PREFACE
     The Office of Radiation Programs of the Environmental Protection
Agency endeavors to protect public health and preserve the environment
by carrying out investigative and control programs which encompass
various sources of radiation.  Pursuant to this goal, the Office's
Criteria and Standards Division and Eastern Environmental Radiation
Facility initiated a study in June 1975 to examine the radiation
impact of living in structures built on phosphate lands.  This study
was carried out in conjunction with the Florida Department of Health
and Rehabilitative Services and the Polk County Health Department.
The purpose of this report is to present the findings of that study;
these include estimates of the radiation levels, evaluations of the
cost-effectiveness of controls, and possible actions that can be taken
to reduce such levels.  Readers of this report are encouraged to
inform the Office of Radiation Programs of any omissions or errors.
Comments or requests for further information are also invited.

     We wish to express our gratitude to the staffs of the Florida
Department of Rehabilitative Services and the Polk County Health
Department for their cooperation and assistance.  Staffs of the
Eastern Environmental Radiation Facility in Montgomery, Alabama, and
the Environmental Monitoring and Support Laboratory in Las Vegas,
Nevada, contributed substantial efforts in sample and data analysis.
We also offer our thanks to officials of the phosphate industry for
their help.
                                   William A. Mills, Ph.D.
                          Acting Deputy Assistant Administrator
                            for Radiation Programs (ANR-458)
                                  iii

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                           TABLE OF CONTENTS
Summary and Findings  	    1




Section 1.0  Introduction	    M




Section 2.0  Problem Description 	    7




Section 3-0  Observed Radiation Levels 	   17




Section 4.0  Radiation Health Risk Estimates 	   29




Section 5.0  Analysis of Control Alternatives	56




Section 6.0  Alternatives for Radiation Protection 	   76




Section 7.0  Socio-Economic Impact 	   90




Section 8.0  Implementation of Radiation Protection Measures ...   97






References	101






Glossary	107






Appendix A   Study Design - Techniques and Procedures




Appendix B   Calibration of Track-Etch Films




Appendix C   Radiation Exposure Control Measures



Appendix D   Evaluation of Field Data
Annex
Individual Structure Data

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                                 TABLES
Table  1 - EPA & DHRS Indoor Radon Decay Product Level
            Distribution by Number of Structures 	   23

Table  2 - Distribution of Indoor Radon Decay Product Levels
            by Land Category	   24

Table  3 - Distribution of Indoor Radon Decay Product Levels
            in Slab and Crawlspace Structures on Reclaimed
            and Mineralized Land	 25

Table  4 - Outdoor External Gamma Exposure Distribution by
            Land Category	   27

Table  5 - Distribution of Indoor Radon Decay Product
            Levels According to Land Classification
            (Track-etch) 	   28

Table  6 - Observed Increase in Lung Cancer Fatality Rate,
            Czechoslovakian Uranium Miners 	   41

Table  7 - Observed Increase in Lung Cancer Fatality Rate,
            Swedish Iron and Zinc Miners	   42

Table  8 - Comparison of Typical Aerosol Characteristics 	   44

Table  9 - Estimated Risk of Lung Cancer per 100,000 Exposed Indivi-
            duals Due to Lifetime Residency in Structures Having an
            Average Radon Daughter Concentration of 0.02 WL (Relative
            Risk Model)	   51

Table 10 - Estimated Risk of Lung Cancer per 100,000 Exposed Indivi-
            duals Due to Lifetime Residency in Structures Having an
            Average Radon Daughter Concentration of 0.02 WL (Absolute
            Risk Model)	   52

Table 11 - Estimated Lifetime Risk of Excess Fatal Cancer and Genetic
            Abnormalities per 100,000 Individuals Exposed
            to an Annual Dose Rate of 100 mrem	   54

Table 12 - Estimated Average Cost of Control Measures for Structures
            Constructed on Florida Phosphate Lands 	   57

Table 13 - Impact of Alternative Criteria for Indoor Radon
            Decay Product Exposure for Structures Requiring
            Special Corrective Action  	   86
                                  vii

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Table B. 1 - Data Used in Analysis 	  B-2

Table C.1 - Estimated Average Cost of Control Measures for
             Structures Constructed on Florida Phosphate
             Land (same as Table 12) 	   C-10

Table D.1 - Distribution of Mean Gross Indoor Radon Decay
             Product Levels	  D-M

Table D.2 - Number of Structures in Specified WL Ranges by City  .  D-4

Table D.3 - Number of Structures by Land Category and Mean Gross
             Indoor Radon Decay Product Level Ranges  	  D-8

Table D.M - Statistical Comparison of Mean Gross Indoor Radon
             Decay Product Levels by Land Category  	  D-8

Table D.5 - Number of Structures by Structure Type and Mean Gross
             Indoor Radon Decay Product Level Ranges  (N=133)  ....  D-9

Table D.6 - Statistical Comparsion of Mean Gross Indoor Radon
             Decay Product Levels by Structure Type 	  D-10

Table D.7 - Number of Structures by City and Specific Outdoor
             Gamma Range 	  D-19

Table D.8 - Average Ratio of Indoor Gamma to Outdoor  Gamma Measure-
             ments by Structure Type 	  D-21

Table D.9 - Average Ratio of Indoor Gamma to Outdoor  Gamma Measure-
             ments by Structure Type for Observations Equal to  or
             Greater than 10 ]aR/hr  	  D-22

Table D-10 - Average Ratio of Indoor Gamma to Outdoor Gamma
              Measurements by Structure Type for Observations
              Equal to or Greater than  15 uR/hr  	  D-23

Table D-11 - Outdoor Gamma Survey Distribution of All Structure
              Sites by Land Category 	  D-25

Table D.12 - Statistical Comparison of  Gamma Survey
              Distribution for Selected Land Categories  	D-26
                                  Vlll

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                                FIGURES



Figure 1 - Phosphate Deposits in Florida 	    8

Figure 2 - Uranium-238 Decay Series	    11

Figure 3 - Typical Profile in Study Area	    12

Figure 4 - Factors Influencing Radon Decay Product Concentrations
           in Structures	    15

Figure 5 - Respiratory Cancer Mortality Reported for U.S. Miners  .    31

Figure 6 - Respiratory Cancer Mortality in Ontario (Canada)
           Uranium Miners	    35

Figure 7 - Respiratory Cancer Mortality Reported in Czechoslovakian
           Uranium Miners (1948-1973)	    36

Figure 8 - Cost-Effectiveness of Remedial Action to Reduce Indoor
           Radon Decay Product Levels for Existing and Planned
           Structures	    63

Figure 9 - Reduction of Gamma Exposure Rate Resulting from Earth or
           Concrete Shielding	    66

Figure 10 - Correlation of Observed Indoor Gamma Exposure with
           Theoretical Estimation	    67

Figure 11a - Cost-Effectiveness of External Gamma Exposure Control for
           Planned Structures (Assuming 4" Concrete Slab Construction
           @ $550)	    70

Figure 11b - Cost-Effectiveness of External Gamma Exposure Control for
           Planned Structures (Assuming 8" Concrete Slab Construction
           § $1,500)	    71

Figure 11c - Cost-Effectiveness of External Gamma Exposure Control for
           Planned Structures (Assuming 12" Concrete Slab Construction
           § $4,000)   	    72

Figure 11d - Cost-Effectiveness of External Gamma Exposure Control for
           Planned Structures (Assuming Excavation and Fill
           @ $15,000)  	    73

Figure 11e - Cost-Effectiveness of External Gamma Exposure Control for
           Existing and Planned Structures (Summary) 	    74

                                   ix

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Figure A.1 - Gamma Radiation Measurements (Reuter-Stokes
             Pressurized Ion Chamber and Ludlum Model 125
             Micro R Meter)	A-2

Figure A.2 - Radon Progeny Integrating Sampling Unit (RPISU) .  .  .  A-4

Figure B.1 - Calibration Formula at 95$ Confidence Level 	  B-6

Figure D.1 - Distribution of TLD Air Sampling Measurements ....  D-3

Figure D.2 - Average Indoor Radon Progeny Working Level Distribution
             (Gross) for Polk County, Florida (N=133)	D-5

Figure D.3 - Distribution of TLD Air Sampling Measurements by
              Land Category and Gross Working Level Range	D-7

Figure D.4 - Distribution of TLD Air Sampling Measurements by
              Structure Type and Gross Working Level Range . .  .  . D-11

Figure D.5 - Distribution of TLD Air Sampling Measurements by
              Structure Type and  Gross Working Level Range for
              Reclaimed Land	D-13

Figure D.6 - Distribution of TLD Air Sampling Measurements
              by Gross Working Level Range 	 D-15

Figure D.7 - Distribution of Outside Gamma Radiation
              Measurements 	 D-16

Figure D.8 - Average Outdoor Gamma Radiation (Gross) for Polk
              County, Florida  	 D-18

Figure D.9 - Distribution of Gamma Exposure Rate by Land
              Category	D-24

Figure D.10 - Distribution of Indoor Gamma Exposure Rate by
               Structure Type for Reclaimed Land	D-28

Figure D.11 - Distribution of EPA Track-Etch Data by Gross
               Working Level Range 	 D-29

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                          SUMMARY OF FINDINGS



     As a result of the presence of elevated concentrations of

radium-226 and other radionuclides in phosphate ores and mining

wastes, many individuals residing in Central Florida are exposed to

undesirable levels of radiation.  In the absence of adequate measures

to protect public health, many more could be exposed in the future,

depending upon developing mining and land use patterns.  The major

exposure problem is associated with structures, principally

residences, that are constructed on, near, or using radium-bearing

materials related to phosphate ores.  In this study, annual average

indoor radon decay product concentrations in excess of 0.03 working

level (WL) were measured in approximately 15 percent of the structures

surveyed.  Normal occupancy at this level of exposure would result in

an annual cumulative exposure of 0.6 working level months  (WLM).

Lifetime residence in a structure exhibiting this level could result

in a doubling of the normal three to four percent risk of  fatalities

due to lung cancer.  At present there are no adequate guidelines to

protect the public from this and most other similar sources.
    *Working level month means exposure to one working level  (WL)
for 170 hours (a working month).  Exposure of non-miners  (75%
occupancy) in residential environments to radon daughters at  one
working level for one year is approximately equivalent to 27 WLM.   A
working level is defined as any combination of short-lived radon
daughter products in one liter of air that can result in the  ultimate
emission of 1.3 x 10^ Mev of alpha energy.  Normal occupancy  is
assumed to be 75 percent residence in this report.

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     Areas affected by the radium-bearing phosphate materials also

generally exhibit elevated gamma radiation exposure levels.  However, the

health risk accompanying exposure to radon decay products in a structure

is generally much greater than that for the associated gamma exposure.

Therefore, assuring protection from elevated air concentrations of radon

decay products is of primary concern, with protection from gamma exposure

of only secondary importance.
                                         *
     Evaluation of the cost-effectiveness  of various measures for

controlling airborne radon decay products in new (i.e., planned) and

existing structures suggests that several appear economically

reasonable.  The application of control measures in a residence was found

to be warranted on this basis when initial levels are greater than 0.005

WL above normal.  Although most of the control measures evaluated have

been tested and used in other situations, none have been thoroughly

tested in Florida.

     The cost of controlling gamma radiation in existing structures is

high because remediation would require extensive modifications to the

foundation and to the soil under and around it.  It was concluded that

the application of control measures to reduce gamma radiation exposure  is

not cost-effective in existing structures.  However, in planning
    *Meaning the degree to which the economic cost of an action  (in
this case, the use of control measures) is justified by the positive
result of the action (e.g., health risk reduction).

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residences, the design and siting of the  structure  can  be  arranged  to




provide additional gamma shielding  for  little  cost.   In most  new




residences, it appears to be cost-effective  to  limit  external gamma




radiation exposure rates to 5 yR/h  above  normal  (11 yR/h gross),  or less.




     Land and wastes associated with other types of ores throughout




Florida, as well as other parts of  the  United States, may  pose similar




health risks due to the presence of radium and  other  radionuclides  in




above normal concentrations.  While these findings  apply to a specific




situation in Central Florida, Federal,  State, or local  authorities  with




similar problems in other areas may find  them useful.   Local  factors,




including cost and other practical  considerations, may  have to be weighed




in applying these results to situations other than  phosphate-related land




in Florida.




     During the course of this study, the Agency also acquired




information about other types of land from the phosphate industry,




universities, and state and local agencies,  as well as  from its  own




measurements.  Sizeable areas of land in  Florida containing monazite sand




deposits or wastes from the processing  of various minerals may also




present health risks similar to those posed  by phosphate lands and




wastes.  Some of these lands may also pose health risks due to radiation




associated with radionuclides resulting from the decay  of  thorium-232.  A




study carried out by the State of Florida to characterize  the  health




impact in these areas would appear  to be indicated, as  a basis for  any




control action that may be necessary.

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                               SECTION 1.0




                               INTRODUCTION








     Naturally-occurring radionuclides such as uranium, thorium, and




their decay products, as well as tritium, carbon-lU, and potassium-40,




are found throughout the environment and are usually fairly evenly




distributed.  However, some geological strata, such as marine phosphorite




deposits, contain significantly elevated concentrations of uranium,




thorium, and their decay products.  In the United States, the phosphate




deposits of Florida contain concentrations of uranium and its decay




products at levels about 30-60 times greater than those found in average




soil and rock.  The presence of this radioactive material in extensive




land areas in Central and Northern Florida creates the potential for




radiation exposure of the general population living on or near  this land.



     In June 1975, the U.S. Environmental Protection Agency (EPA), in



conjunction with the Florida Department of Health and Rehabilitative




Services and the Polk County Health Department, initiated a pilot study




to examine the radiological impact of living in structures built on




reclaimed phosphate land.  The-study was a part of a comprehensive




investigation conducted by EPA of the overall impacts of releases of




radiation and radioactive materials directly or indirectly from the




phosphate industry.

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     In September 1975, the Administrator of the Environmental Protection




Agency informed the Governor of Florida that the Agency had found



elevated radon decay product levels in buildings constructed on  land



reclaimed from old phosphate raining areas (Tr 75).  He noted that the



primary health concern is increased risk of lung cancer to the



occupants.  The Administrator recommended that "as a prudent interim



measure the start of construction of new buildings on land reclaimed from



phosphate raining areas be discouraged."



     As a result of the Agency's preliminary findings, discussions were



held with appropriate Federal, State, and local agencies, as well as



industry representatives to determine the appropriate course of  action.



The following actions were determined to be of principal  importance:



     1.  Complete an assessment of the health risk in the study



structures over a longer period of time.



     2.  Perform an evaluation of the number of structures affected and



the magnitude of the impacted land within the State of Florida.



     3-  Develop guidelines for use by the responsible agencies  and the



public in determining acceptable indoor radiation levels.



     JJ.  Develop guidelines for use by the responsible agencies  and the



public in evaluating existing structures for possible remedial action.



     5.  Develop criteria for evaluating the indoor radiation exposure



potential of undeveloped land.



     6.  Determine if new reclamation techniques are needed and  feasible.

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     The activities of the Environmental Protection Agency since  then




have been focussed on actions one, three, four, and five, with the State




and local health agencies focussing on actions two and four.  Industry




efforts have been focussed on action six.  However, in order to evaluate




the problem expeditiously, there has been an exchange of data and




information on each of these items among all groups involved.




     The purpose of this report is to present data gathered in the EPA




study, estimate the radiation levels in existing structures, evaluate the




cost-effectiveness of controls, evaluate the social and economic  impact




of potential radiation protection controls, and delineate the




alternatives available for radiation protection to minimize adverse  risk




to the public.  A separate report will address item five, i.e., the




development of criteria for the evaluation of undeveloped land to




determine its suitability for residential development.

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                               SECTION 2.0




                           PROBLEM DESCRIPTION








2.1  INDUSTRY OVERVIEW




     In 1975 about 83 percent of U.S. phosphate mine rock production




occurred in Florida, primarily in the Central Florida Land-Pebble




district with the remainder in Tennessee and several western states  (St




77).  Figure 1 illustrates the primary Florida phosphate deposit areas.




About 17M million tons of phosphate mine rock was extracted in  1975




through the strip mining of approximately 5,000 acres of land.  Over  the




80 years that phosphate has been mined in Florida, a total of about  2




billion tons of phosphate mine rock has been extracted from about  120,000




acres of land (St 77, Wa 71*).








2.2  MINING TECHNIQUES & PRACTICES




     The standard mining practice in the Florida land-pebble phosphate



fields is to strip the overburden and mine the phosphate matrix with




draglines.  Electric-powered walking draglines with 35 to 70 cubic yard




buckets work in cuts varying from 150 to 250 feet in width and  from  a few




hundred yards to a mile or more in length.  The cuts are from 50 to  70




feet deep.  Overburden is stacked on unmined ground adjacent to the




initial cut by means of a dragline, until successive cuts allow it to be




cast into adjacent mined-out cuts.  As each cut is stripped of  overburden

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                                                           JACKSONVILLE
                                            I'oBORO
                                         PLANT CITjr/JV®
                                     TAMPA ®
               n land-pebble c

         Hardrock district

         Central  land-pebble
Figure 1.   Phosphate  deposits in  Florida.   (WA 74)

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and then mined, the ore is stacked in a suction well  or  sluice  pit  that




has been prepared on unmined ground.  High pressure water  is  used  to




produce a slurry of about 40 percent solids from  the  matrix.  This  slurry




is then pumped via pipe to the washer plant.  In  this manner, a typical




operation will mine about 400 acres of land, remove 13 million  cubic




yards of overburden, and mine 9 million yards of  matrix  per year.




     Water is used in the phosphate beneficiation or  ore refinement




process, in addition to being used as a transportation medium.   Both




fresh water from deep wells and reclaimed water from  slime settling ponds




are used by the phosphate industry, at a rate of  approximately  10,000




gallons to produce one ton of marketable phosphate rock.   As  the mining




progresses, mined-out areas are used for the disposal of tailings and




slimes, in addition to overburden.  Approximately one ton  of  slimes and




one ton of sand tailings must be disposed of for  each ton  of  marketable




phosphate rock produced.  Some of the sand tailings and  overburden  are




used to construct retaining dams in mined-out areas,  behind which




phosphatic clay slimes settle and dewater.



     Beneficiation methods differ slightly, depending on screen analysis




of the feed, the ratio of washer rock to flotation feed, the  proportions




of phosphate, sand, and clay in the matrix, and equipment  preferences.




Through a series of screens, in closed circuit with hammer mills and log




washers, the matrix is broken down to permit separation  of the  sand and




clay from the phosphate-bearing pebbles.  Three concentrations  of




marketable phosphate rock are produced:  a 3/4-inch by 14-mesh  pebble,  a

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coarse 14 by 35-mesh fraction, and a fine 35 by 150-mesh fraction.  The




washed, oversized pebble fraction is a final product.  The  14 by  35-mesh




fraction is called the coarse feed, from which a coarse concentrate is




obtained by gravity and flotation processes.  The tailings  or waste from




this fraction are used in dam construction or land reclamation.   The  35




by 150-mesh fraction is processed through a flotation section to  recover




a fine concentrate. The waste, a clay slime, is impounded in areas that




have been mined.








2.3  PRESENCE OF RADIOACTIVE MATERIALS




     Uranium is present in the phosphate matrix in concentrations which




generally average about 100-150 ppm (or about 35-55 picocuries natural




uranium per gram of matrix).  The uranium is usually in equilibrium with




its radioactive decay products, at least through radium-226 (Gu 75).




This means that for each curie (a measure of radioactivity  equal  to




3-7x10   disintegrations per second) of the parent radionuclide,  one




curie of each daughter radionuclide is also present.  The uranium-238



decay scheme is shown in Figure 2.



     Radioactivity is also present in parts of the overburden.  Figure 3




illustrates the general geological structure found throughout much of the




Florida land pebble district.  A "leach zone," which averages five feet




thick and covers much of the pebble deposits, contains uranium in




concentrations comparable to that of the matrix.  In some areas other




portions of the overburden also contain elevated radioactivity, although
                                     10

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                                                         ATOMIC WGT.
                                                             ELEMENT
                                                         ATOMIC NO.
                                                         HALF-LIFE
Figure 2.   Uranium-238 Decay  Series
                                       11

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                 LEACHED ZONE
                                        :0' TO 10'::::
9 (MATRIX);fCLAY                    • 5 J u **>•. ••







           '                        ^
 Figure 3. Typical Profile in Study Area (Fo 72)
                            12

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not in as high concentrations  (Ca  66).   The  radioactivity is  generally




associated with the phosphate,  itself,  since the  uranium replaces the




normal calcium in apatite.   Consequently,  the marketable ore  and slimes




containing most of the phosphate also contain most  of the associated




radium.  Two-thirds of the phosphate originally contained in  the matrix




remains in the marketable rock, with the remainder  primarily  in the




slimes.




     Soil throughout the United States  typically  contains between 0.2 and




3 pCi radium-226 per gram.   One would anticipate  that normal  Florida




soils would contain this concentration  range of radium-226 in areas that




have been undisturbed by mining.   However, anomalies  may occur in areas




where surface waters have exposed  phosphate  deposits  or  where such




deposits are very close to the  surface.  Measurements indicate that the




latter situation occurs in several areas in  Central Florida.








2.4  ORIGIN AND TRANSPORT OF RADON-222




     Unmined, reclaimed and  disturbed phosphate land  can be composed of



widely varying concentrations of radium-226,  as a function of the




relative thickness and presence of low  activity overburden soil  and sand




tailings as compared to higher activity matrix, slimes,  or leach zone




material.   The presence of radium-226 and  its decay products  in  soil




presents a potential source of gamma exposure to individuals  living or




working above the soil.   However, of much  greater concern  is  exposure




arising from the release of radon-222,  a noble gas decay product of
                                    13

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radium-226 with a 3-85-day half-life.  It may diffuse through the soil

into the atmosphere, where observed radon-222 concentrations in the air

are highly variable due to the influence of factors such as precipi-

tation, barometric pressure, and atmospheric thermal stability.

     Radon-222 that diffuses up through soil also readily passes through

most concrete slabs and other construction materials. Within a structure,

the principal route of removal of radon is by ventilation or leakage

through the structure's walls, window frames, etc.  Radioactive decay of

the material as a removal process is generally small compared to

ventilation and leakage.  Radon-222 is probably not in equilibrium with

its decay products in most situations within structures, due to the

effects of ventilation and plate-out of decay products as  particulates
                   *
on inside surfaces.   The level of radon-222 and its decay products is

thus dependent upon the rate at which radon diffuses into the structure

and the rate at which it is removed by ventilation, leakage, and decay.

Clearly, if ventilation is low, radon and its decay products have the

potential to build up significantly within a structure. Figure 4 depicts

the movement of radon and daughters into and out of a structure.
     The degree to which plate-out  is  a  contributing  factor  is
highly variable, depending primarily upon exposed  surface  area  and  the
free ion fraction; the effect of plate-out, however,  is  of relatively
small significance in comparison with  that  due  to  ventilation.

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                            EQUILIBRIUM RADON
                          PROGENY CONCENTRATION
                             (WORKING LEVELS)
                                            I  I'LATF OUT
VENTILATION
                       RADON
                      SEEPAGE
                      THROUGH
                                  DIFFUSION
                                  RADON
                                EMANATION
                          SOIL CONTAINING RADIUM 226

FIGURE 4.
FACTORS INFLUENCING RADON DECAY PRODUCT CONCENTRATIONS IN STRUCTURES

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     Radon-222 which enters  the atmosphere  via  transport through soil can




originate from hundreds of feet below  the surface,  but  because of its




relatively short half-life and the  time  required  for  diffusion through




most soils, the first 20 feet of soil  is usually  the  major source.   This




effective source thickness can be reduced to  just a few feet if the soil




has a high water content.
                                     16

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                               SECTION 3.0




                        OBSERVED RADIATION LEVELS








3-1  NORMAL BACKGROUND LEVELS








3-1.1  General Perspective




     Exposure to background radiation results principally  from  cosmic




radiation sources and normal concentrations of radioactive elements




originating in the atmosphere of the earth's crust.  Both  of  these




components vary throughout the United States, depending upon  altitude,




latitude, and the makeup of the terrestrial environment.   However, in




some areas the presence of elevated soil radioactivity due to either




natural phenomena or to human alteration of the environment can  lead to




radiation exposure significantly in excess of normal background




exposure.  The purpose of this section is (1) to place the radiation




levels observed in Central Florida structures built on phosphate land in



perspective with radiation exposure levels generally expected in Central




Florida and in other parts of the country, and (2) to provide a  framework




for decision-making regarding measurement of radiation levels and




implementation of radiation protection recommendations in  situations




where the exposures are elevated.
                                    17

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3.1.2  Cosmic Ray Exposure




     Whole body dose rates at sea level in the United States from Florida




to Alaska range from about 30 to 45 mrem/year (3-4 to 5.1 yrem/h),




respectively.  At 45 N latitude, the variation with altitude from sea




level to 8,000 ft. is about 40 to 200 mrem/year (4.6 to 22.8 yrem/h),




respectively (Kl 72).  In general, the estimated annual cosmic-ray




whole-body doses in the U.S. range between 30 mrem for Hawaii to 130 mrem




for Wyoming.  For Florida it is estimated to be 35 mrem.




     In order to verify this estimate for Florida, measurements were at




the center of two reasonably large Central Florida lakes with a




pressurized ion chamber.  The measured cosmic-ray contribution, excluding




the neutron component, was 35 mrem/y (4.0 yrem/h) at Lake Pierce and 31




mrem/y (3.5 yrem/h) at Lake Hamilton for an average of about 33 mrem/y




(3.8 yrem/h).  The measured values at the two lakes agree quite favorably




with those previously reported.  The neutron component could add an




additional 6 mrem/y  (0.6 yrem/h), but this will be ignored  because




external radiation measurements made in Central Florida as  cited in this




document do not record neutron dose (Lo 66).








3.1.3  Terrestrial External Gamma Ray Exposure




     Naturally radioactive isotopes are constituents of a number of




minerals present in the terrestrial environment.  Naturally-occurring




radionuclides contribute to both external and internal irradiation.  The




significant external gamma exposures are produced by potassium-40 and  the




decay products of the uranium and thorium series.
                                     18

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     Based upon numerous reported measurements, estimates have been made




of the range and mean of whole-body doses due to terrestrial radiation  by




population and by area for the United States.  Ninety percent of all




areas fall in the range of 15 to 130 mrem/year (1.7 to  14.8 yrem/h),




while ninety percent of the population falls in the range of 30 to 95




mrem/year (3.4 to 10.8 yrem/h).  The estimated national mean is 55




mrem/year (6.3 yrem/h).








3.1.4  Total Background External Radiation Levels




     Total average background radiation levels in the various States have




been estimated to range between 70 mrem/year (8 yrem/h) and 225 mrem/year




(26 yrem/h) with an overall U.S. average of about 85 mrem/year




(10 yrem/h).  The average of 879 measurements of natural background




levels by Levin, et al^., in Florida was 59 mrem/year (6.7 yrem/h)  (Oa72).




     Measurements of the total normal background in Central Florida were




made by EPA in several locations with various types of  detection



equipment.  The average outdoor gamma exposure levels measured with




portable scintillation instruments at 26 structures built on unmined




non-mineralized land was 45 mrem/year (5 yrem/h).  For  these same



structures, indoor gamma exposure levels averaged 43 mrem/year




(4.9 yrem/h).  TLD's were placed in Dundee, Lake Wales, and Polk City,




Florida, which are outside the phosphate area, and left for an extended




time period.  The average of these measurements was 41 mrem/year




(4.7 yrem/h).  Pressurized ion chamber measurements were made at nine




locations outside the phosphate region.  The average of these




measurements was 51 mrem/year (5.8 yrem/h).  It should  be noted that the
                                    19

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measurements by portable scintillation instruments and TLD's will not




reflect cosmic ray exposure as accurately as the pressurized ion




chamber.  Considering this, these field data show adequate




intercomparison as well as agreement with the values listed in  the




literature.  They suggest that the normal external gamma exposure in




Central Florida is about 60 percent of the average for the United States.








3-1.5  Radon-222 and Decay Product Exposure




     Natural radionuclides are also present in the air.  The greatest




dose to people from airborne natural radioactivity generally arises from




the decay products of Rn-222.  Measurements of radon-222 concentration  in




air in the U.S. suggest that it is normally present in concentrations




ranging from 40-1000 pCi/m^ (0.04 - 1 pCi/1) (Na75).  Radon in  the




atmosphere primarily originates from the decay of radium in soils and




rocks.  The outdoor radon concentration at ground level depends on the




rate of radon emanation from the soil and how rapidly it is dispersed.



     Inside structures the concentration of radon-222 and its decay




products is generally considerably higher than corresponding outdoor



concentrations because of poorer indoor dispersion characteristics.



Although the number of measurements made over extended time periods




throughout the United States is quite limited, the data suggest that  the




normal range of radon decay product levels is from about 0.0001 to 0.005




working level  (WL), with an average of about 0.002 WL.  Although  levels




greater than 0.005 WL can be found, these are frequently due to



combinations of larger than normal radium-226 concentrations in soil  and
                                     20

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building materials, coupled with poor ventilation.  Measurements  by EPA




using the TLD air pump system in Central Florida  in 26  structures on




non-mineralized land showed an average of about 0.004 WL  (.0007-.014




WL).  Data obtained by the University of Florida  and the  State  Department




of Health and Rehabilitive Services for this parameter  on non-phosphate




land are 0.002 and 0.004 WL, respectively (De ?8, Ro ?8).   Review of




these data indicates that the range is within that expected by  studies  of




other investigators throughout the United States.  Further,  the three




data sets compare quite favorably, although the University of Florida




data is for a smaller sample of residences measured using only  a  few grab




samples.








3.1.6  Other Anomalous Radiation Areas in Florida




     In addition to the phosphate lands in Florida there  are other




regions in the State where elevated radiation levels have been  noted,




because of the presence of ores containing trace  quantities of  uranium,



thorium, and their decay products.  These areas are primarily along the




coast between Punta Gorda and Venice, and along the northeastern  coastal




region.  Deposits of monazite sands are the primary source  of radioactive




materials.  In these areas, radiation levels are  as high  as  or  higher




than those observed in the phosphate region.  Little detailed information




is available regarding these areas because they have not  been




investigated to any meaningful extent.  Limited measurements by EPA




around Punta Gorda and Venice identified external gamma radiation




exposure levels up to 30 viR/h (260 mrem/y).   However, the  size  of  the




impacted areas appears to be small.   In the northeastern  area of Florida,
                                    21

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gamma radiation exposure levels in excess of 100 yR/h (880 mrem/y) have




been reported by the State of Florida Department of Health and




Rehabilitative Services. They also suggested that the impacted area in




this region could be quite large.  No information exists on radon-222 and




radon-220 concentrations in these areas.








3.1.7  Background Summary




     Based upon EPA's measurements and review of previously reported




data, it is concluded that the normal background radiation level in and




around a Central Florida structure located away from phosphate-related




land can be characterized by the following parameters:




         External gamma exposure rate - 6 Urem/h




         Indoor radon decay product level - 0.004 WL




     Although these values are somewhat variable, as indicated by  the




data, they provide a representative basis for most decisions concerning




the need for remedial action for radiation protection.








3.2  SUMMARY OF RADIATION MEASUREMENTS AND EVALUATIONS




3-2.1  Evaluation of Radon Progeny Levels in Structures



     Radon progeny levels were evaluated at 133 locations in Polk  County




with Radon Integrating Progeny Sampling Units (RIPSU).  This device draws




air through a particulate filter, and measures radiation from  radon




progeny with a thermoluminescent dosimeter (TLD).  These air sampling




units were rotated to the various locations on a periodic basis  to insure




several measurements at each structure, and to reflect any seasonal or
                                    22

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diurnal variations in radon decay product concentrations.  For the

purpose of evaluation, the 133 locations were categorized according to

structure type (slab, basement, crawl space, or. trailer construction) and

land category (reclaimed, mineralized, or non-mineralized).  Of the total

sample, 22 structures were from the original pilot study initiated by EPA

and the remainder were selected later as a part of the group chosen by

the Florida Department of Health and Rehabilitative Services (DHRS).  The

distribution of indoor working level measurements in the two samples

differs, although this is expected due to the smaller pilot study sample

size and the practical aspects of selecting the structures.  In the

selection of the EPA pilot group, houses known to be on reclaimed land

were chosen on the basis of elevated external gamma measurements made on-

site.  The DHRS study group, however, was selected solely by review of

land records to identify reclaimed land.  It is understandable,

therefore, that a greater percentage of structures in that group exhibit

lower external gamma and indoor radon decay product levels than in the

EPA pilot group.  The distributions of radon decay products in each group

are shown in Table 1.
                                 TABLE 1
              EPA and DHRS Indoor Radon Decay Product Level
     Distribution by Number of Structures (Percentage in parenthesis)

          Level (WL gross)         EPA       DHRS        Composite
         Greater than 0.05
         0.03 to 0.05
         0.01 to 0.03
         Less than 0.01
N=22
5 (2350
3 (14$)
4 (18$)
10 (U5$)
N=111
3 (2$)
9 (9$)
22 (20$)
77 (69$)
N=133
8 (6$)
12 (9$)
26 (20$)
87 (65$)
                                    23

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     From information collected in the survey, the land on which the

structures were constructed was classified according to four categories:

non-mineralized (no deposits), mineralized (deposits present, but

unmined), reclaimed, and other (i.e., missing or incomplete

information).  Of the 133 structures, the gross average working level  for

each category is 0.003 WL (non-mineralized), 0.015 WL (mineralized),

0.016 WL (reclaimed), and 0.018 WL (other).  This distribution, provided

in more detail in Table 2, indicates that mineralized land has as much

radiological impact as reclaimed land.



                                 TABLE 2

                Distribution of Indoor Radon Decay Product
                         Levels by Land Category

Land Use

Reclaimed

Mineralized

Non-mineralized

Unknown


In order to  determine the influence  of structure design  (particularly

foundation design)  on radon diffusion, the average working level

measured in  various types of  structures was evaluated for four  typical

structure types found in  central Florida:  basement, slab-on-grade,

crawl  space, and trailers.  The average value  for each category (with

the  number of  structures  in parenthesis)  is 0.020 WL  (4), 0.015 WL

(102), 0.01  WL  (13), and  0.008 WL  (14), respectively.  Although sample
N
93
9
29
2
WL<0.01
59$
44$
97$
0
0.01 <.WL <0.03
20$
44$
3$
100$
0.03 
-------
size for some of these categories decreases the statistical

significance of this distribution, this data suggests that crawl space

and trailer designs result in less radon diffusion into a structure

than typical basement or slab-on-grade construction.

     The evaluations of indoor radon decay product levels by both land

category and structure type can be combined to analyze the

distribution of measurements as a function of these two parameters.

For reclaimed land, the four types of structures were evaluated on the

basis of percent working level distribution.  For slab and crawl space

construction the distributions are shown in Table 3.


                                 TABLE 3

      Distribution of Indoor Radon Decay Product Levels in Slab and
     Crawl space Structures on Reclaimed and Mineralized Land (RPISU)

         Level (gross WL)          Slab          Crawlspace
                                             (including trailers)
                                    N=77            N=22

         Greater than 0.05             9%              0%
         0.03 to 0.05                 12$              9%
         0.01 to 0.03                 23%              9%
         Less than 0.01               56$             82$


     Ventilation has been identified as a key factor in the buildup of

indoor air concentrations of radon decay products.  The use of air

conditioning in the study structures was of interest because it was

initially believed that maintaining a lower indoor temperature at a

reasonable cost would entail reducing the degree of air infiltration

from the outside air.  However,  studies by EPA show that operation of
                                   25

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a central air conditioning system tends to reduce the indoor radon




decay product levels when compared to no air flow (Wi 78).  This is




attributable to the increased influx of outside air due to leakage




surmised to be the result of pressure differences brought about by the




operation of the ventilation system, as well as the deposition or




"plate-out" of decay products in the ventilation system.  For




structures with and without air conditioning the average working




levels are 0.012 and 0.016 WL, respectively. This implies that any




significant short term effects caused by operation of the air




conditioning system may be largely balanced over a year by factors




such as decreased usage during the cooler months.








3.2.2  Evaluation of Gamma Exposure Levels




     Gamma exposure rate measurements were made at 1102 sites by EPA



and DHRS.  The gamma surveys were performed with a standard portable




scintillometer held one meter from the floor or ground level for



indoor and outdoor measurements, respectively.  Average indoor and




outdoor gamma exposure rates were estimated from several measurements




in and around each structure.




     The distribution of exposure rates was examined for different




land categories.  This is summarized in Table 4 for the three primary




categories:  non-mineralized, mineralized and reclaimed.
                                    26

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                                 TABLE H
                     Outdoor External Gamma Exposure
                        by Land Category  ^=107*0*

      Level (yR/h)          Reclaimed     Mineralized   Non-Mineralized
N=672
1%
2b%
67%
11 yR/h
N=102
1$
4*
95$
7 yR/h
N=300
0%
3%
97%
6 yR/h
     greater than 20
     11-20
     less than 11
     average gamma exposure

*28 sites have unknown classifications


     The influence of structural design, especially the degree of

foundation shielding, was evaluated for the four structure types

considered in this study.  The average ratio of indoor gamma levels to

corresponding outdoor gamma levels was found to be fairly similar for all

structure types (about 0.8-0.9, as shown in Figure D.8).  However, when

controlling for gamma background "noise" contribution (e.g., from

reflected primary radiation and radiation from structural materials

themselves, the differences due to shielding are more pronounced for

foundation (slab and basement) versus non-foundation (crawl space and

trailer) structures.  For levels above 10 and 25 yR/h, for example, the

average indoor to outdoor ratio for these respective structure categories

is roughly 0.4 and 0.8 (see Tables D.9 and D.10)  These observations are

consistent with the degree of floor shielding present with slab and

basement construction, which have several inches of concrete, and with

crawl space and trailer construction, which have either wood or thin
                                    27

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metal flooring.  In addition, a distribution plot by  structure  type  for

reclaimed land (Figure D.10) shows that only crawl space and  trailer

structures have indoor levels in excess of 20 pR/h.



3.2.3  Evaluation of Track-etch Data

     Track-etch film was used in 153 structures selected in the pilot

study for the purpose of providing another estimation of radon  progeny

levels.  The film was placed in a structure for at least a year,  after

which a representative portion of the "etches" were counted to  determine

alpha energy deposition.  This was translated into an estimate  of indoor

radon decay product level through the use of appropriate calibration

curves.  The details of this method are discussed in  Appendix B.   Because

of the errors involved in this technique, particularly  at indoor radon

decay product levels less than 0.02 WL, the amount of useful  data

obtained is limited.  Table 5 shows the distribution  of track-etch data

according to land classification.


                                 TABLE 5

                   Distribution of Indoor Radon Decay
       Product Levels According to Land Classification  (Track-etch)
     (M= Mineralized, N=Non-Mineralized, R=Reclaimed, and U=Unknown)

          Level (WL)           M          N        R      U
                              T"         27       112    ~T~

         Greater than 0.05    38%         0%      23%     0%
         0.03 to 0.05          0%         W       12*     0%
         0.01 to 0.03         50%        41*      37$    33/6
         Less than 0.01       12*        55%      28%   67%
                                     28

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                              SECTION 4.0




                    RADIATION HEALTH RISK ESTIMATES








4.1  THE RISK TO HEALTH DUE TO THE INHALATION OF  RADON  DAUGHTERS




4.1.1  The Epidemic-logical Data Base




     The carcinogenic nature of inhaled radon and its daughter




products became known through observation of fatal lung disease in




some groups of underground miners.  The malignant nature of  their




disease was recognized as early as 1879 and specifically identified as




bronchiogenic cancer in 1913 (Lu?1).  The association between these




cancers and the miners' exposure to radon was first made in  1924.




     Although there has been some argument that occupational hazards




other than radon may be important, extensive studies have excluded




many suspected causes of excess lung cancer among underground miners




such as pneumoconioses, water in the mines, heredity, fungal growths,




as well as a number of metals in the ore, i.e., nickel,  chromium,



arsenic, and bismuth (Fr48, Hu66).  Exhaust fumes  from  diesel engines




are often mentioned as a causative factor for lung cancer among




uranium miners.  Yet from 1869 to 18?8, well before the diesel engine



was patented in 1892, lung cancer caused 75 percent of  miner deaths at




Schneeberg (Ha79).  The observation of excess lung cancer mortality in




workers in a variety of hard rock and metal mines  indicates  that




uranium ore dust is not critical to the development of  lung  cancer
                                   29

-------
(Fr48, Hu66, Lu71).  The only common factor identified in all miner



groups studied is the presence of radon and radon-daughter aerosols in



the respired air (Mi?6).



     The general recognition of the radon problem has resulted  in a



number of epidemiological studies in various countries, including the



U.S.A., Canada, Czechoslovakia, Sweden, and Great Britain.  Lung



cancer deaths in U.S. uranium miners have been the subject of an



extensive epidemiological study led by the U.S. Public Health Service



(Lu71, Ar7**, Ar76), which has provided much information on the



etiology of radiation-induced lung disease.  Nevertheless, this study



and to a lesser extent other studies of cancer deaths among under-



ground miners have limitations when used for the purpose of providing



risk estimates applicable to the general population.  The relative



importance of these limitations has been considered  in the risk



estimates made below.



     The estimates of the risk to miners have continued to rise as



more epidemiological data have accumulated.  In this regard it  is of



interest to compare recent information on radiogenic lung cancer with



that available in  1970-1971 when the Federal guide for occupational



exposure of miners was reduced from 12 to 4 Working  Level Months  (WLM)



per year (Fe71).  These guides were based almost exclusively  on the



experience of U.S. uranium miners exposed to high concentrations of



radon  daughters.  At that time 70 lung cancer cases  had been  observed
                                    30

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in the study group.  While this number of  cases  exceeded  the  expected




number of 12, about half of  the cancers  followed exposures  of more




than 1800 WLM (Lu7D.



     Figure 5 shows the number of  lung cancer  cases  observed  in the




U.S. uranium miner study group through September 1968,  and  their




estimated levels of exposure in WLM.  The  expected number of  deaths




depends on the number at risk at each dose level and is based on white




males in the four western states where the uranium mines  were in




operation (Lu?1).  Three things are worth  noting in  these early



results: the small number of deaths in each broadly  defined exposure




category, the relatively constant  ratio  of expected-to-observed deaths




below 1800 WLM, and finally  the absence  of any significant  difference




below 120 WLM.  For these reasons  alone, it is easy  to appreciate why




early estimates of the risk  due to radon inhalation  were  controver-




sial; there was essentially  no dose response information  available.




More recent data, described  below, differs considerably from  these




1968 results.




     A fundamental limitation in this and  similar investigations of



lung cancer mortality is that the  U.S. study is  still in  progress.




Survivors in the U.S. study are continuing to  die of lung cancer with




the result that more recent data show a much larger  number  of lung




cancer deaths than was originally projected (Na?6).  Another  very




serious limitation, peculiar to the U.S. study,  is that the cumulative




exposures to the 4000 workers involved were quite large, averaging
                                   31

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        WHITE U.S.  URANIUM  MINERS (1950 — 1968)

3 DEATHS
10
O
UJ
0
Z
r* in
'IRATORY C
C
(0
UJ
•** _
DC 0
-
-


-
=-"


OBSERVED
I I

EXPECTED
* ~
•
M
III I





I
tf \





\
^-~-f/
    120   360
 840                      1800
CUMULATED  EXPOSURE IN  WLM
3720
Figure 5.      RESPIRATORY CANCER MORTALITY REPORTED FOR U.S. URANIUM MINERS (Lu71).
                         SEE TEXT FOR LIMITATIONS ON DATA

-------
nearly 1000 WLM per miner. There is some evidence  that  at  such high




levels of exposure the risk per unit exposure  is somewhat  less than




occurs at radon daughter exposures below a  few hundred  working level




months (Lu?l, Na?6).  In addition, the  lung cancer mortality  data for




Japanese atomic bomb survivors also shows a trend  for increasing lung




cancer risk per unit dose at lower doses (Un77).   For this reason it




is advisable in risk analysis to limit  the  use of  epidemiological data




for miners to that obtained at moderate exposure levels, i.e.,  a few




hundred working level months.




     The limited information available  from the study of the  U.S.




uranium miners can be augmented by using results derived from epi-




demiological studies of miner health in other  countries and in other




types of mining operations. The occupational environments  in  these




mines differed substantially from those in  the U.S.  underground




uranium mines so that the cumulative exposure  from radon decay




products was much smaller (Mi?6, Se?6,  Sn?2*).   In  addition, the




reported follow-up period in some of these  studies is longer  than for




the U.S. study population.  In all study groups, however,  some miners



are still alive and the final number of lung cancer  cases  is  expected




to be larger.  The absence of data from completed  lifetime follow-up




studies can lead to a biased underestimation of the  risk due  to the




inhalation of radon daughters, unless appropriate  risk  models are




utilized which recognize that current studies  have not  been




completed.  This important topic is discussed  below.
                                   33

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     The direct proportionality of cancer risk to radon decay product




exposure at levels likely to be experienced in the environment  cannot




be demonstrated for either human populations or by animal studies




because of the large number of subjects needed.  As shown below, the




available data indicate that the use of a linear response curve  for




humans exposed to low concentrations of radon decay products is  not




expected to greatly overestimate or underestimate their cancer  risk




provided that the exposures do not exceed a few hundred working level




months.  Figure 6 illustrates the observed cancer excess in Canadian



uranium miners who were exposed to much lower concentrations of radon




decay products than are common in U.S. uranium mines,  (c.f. Figure 5).




Although this study may not be fully adequate to establish a quanti-




tative estimate of the risk per working level month because data on




smoking histories is incomplete, these data have been  shown to  be




consistent with a linear dose response relationship at relatively low




levels of exposure and strongly argue against a threshold dose  for



radiocarcinogensis in the lung (Mi76).




     Figure 7 shows results obtained by J. Sevc and co-workers,  from



their study of uranium miners in Czechoslovakia whose  mining experi-




ence started after 1948 (Se76).  In that country, excess lung cancers




had been observed in uranium miners exposed before World War II.  An




appreciation of this led to better ventilation of the  uranium mines




and resulted in relatively low levels of exposure to miners entering




the work force after 1947.  The average follow-up period in this

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-------
group is twenty three years.  The high degree of correlation  between




exposure and excess cancer shown represents an overall average  for




workers of various ages.  This study also found that  the absolute




cancer risk increased substantially with the age at which a worker




entered this work force.




     Tt should be noted also that epidemiological data of the kind




illustrated in Figures 6 and 7 will always overestimate the exposure




to radon decay products needed to initiate a lung cancer.  The




exposure considered in these studies is that accumulated throughout




the working life of these miners.  The dose received  but ineffective




in producing cancer between the period of cancer initiation and its




manifestation is not discounted,  For chronic exposure, the same




reasoning applies to determining the minimum exposure level at  which  a




significant number of cancers occur; an apparent threshold dose will




exist, unless the cancer is initiated on the last day of exposure.








4.1.2  Risk Estimates for Underground Miners




     Estimates of the cancer risk due to the inhalation of radon decay



products can be made either on the basis of the dose  delivered  to the




basal cells of the bronchial epithelium or the cumulative exposure in



WLM.  In 1972 the NAS-BEIR Committee used the former  method to  prepare




their risk estimates so that other types of ionizing  radiation  could




be considered also (Na 72).  More often estimates of  the risk due to




radon decay products are based on the cumulative exposure in  WLM




(Lu71, Ar76, Na76, Un77, Mi76, Se76,
                                   37

-------
     The dose to the bronchial epithelium has been calculated  by




several investigators (Wa77, Ha?1*, Ha72).  While valuable, these




studies indicate that the dose (in rads) is highly dependent on a




number of factors which have varying degrees of certainty.  One




important, but as yet poorly known, parameter is the depth below the




mucosal surface at which the sites in irradiated tissues giving rise




to lung cancer are located. This distance, which is likely to  differ




in various portions of the respiratory tract, is not known with any




accuracy.  In addition, no information is available on  the degree  of




uniformity of deposited daughter products in various parts of  the




bronchial tree.  Furthermore, the in situ absorption and removal




pattern of the radon decay products lead-214 and bismuth-214 is poorly




understood.  Recent experimental evidence indicates that to postulate




their complete decay in the mucus near the bronchial epithelium, as is




usually done, is likely to be in error (Ja77).  Because of the uncer-



tainty in calculated doses, the Agency prefers to base  estimates of




the risk due to radon decay products on  the cumulative  exposure in




working level months.



     The 1972 NAS-BEIR Report used two types of analyses in estimating




the radiation-induced cancer risks from  follow-up studies of exposure




groups (Na 72).  One, called the absolute risk estimate, is the num-




erical increase in the number of excess  cancers per unit of exposure,




averaged over all age groups.  The other, tne relative  risk estimate,




is the estimated percent increase in excess cancer per  unit exposure
                                   38

-------
Either of these models will yield the same number of excess cancers




for a given study population if based on data from a lifetime follow-




up period.  Because exposed persons have been followed for a shorter




duration, a choice between these models is needed.  In the exposed




groups studied, the risk of radiogenic lung cancer, but apparently not




all cancers, increases with the participants age in about the same




manner as the "natural" incidence of lung cancer, i.e., the relative




risk remains constant.  In contrast, the absolute risk estimates




derived from the U.S. study are not constant but have continued to




increase as the length of the follow-up period is increased (Na?6).




Lung cancer mortality among Japanese survivors has shown a similar




pattern (Be77).  Moreover, analysis by age shows the Czechoslovakian




and Canadian lung cancer data to be grossly inconsistent with the




absolute risk hypothesis (Mi76, Se76).




     More recently, the Japanese cohort data on lung cancer mortality




for those exposed to high LET bomb radiation at age of 50 or more have




been examined for the time of occurrence of excess lung cancer after




exposure (La78).  Because of their age, a near lifetime follow-up




study of this group is possible; the youngest surviving member was




nearly 80 at the time of the study.  Lung cancer mortality was



compared for two dose ranges, those highly exposed, where three times




the expected number of cancers was observed, and a control group




receiving 0 to ten rads ("tissue kerma" in air).  The time to




occurrence of the lung cancers is the same for the two groups, as




would be expected if the increase in lung cancer mortality follows the
                                   39

-------
temporal pattern predicted by a relative risk model.  This is similar




to observed patterns of lung cancer observed in animals following




Plutonium inhalation (Na 76).  In the analysis of these data as they




apply to human health risks the 1976 NAS Report stated, "as already




indicated, the steepness with which lung cancer death rates in the




Battelle (Northwest Laboratory) beagles rose as a function of age




strongly suggests that the relative risk estimate is the appropriate




one to use in the present context of assessing lung cancer risk from




alpha emitters."  For these reasons, relative risk estimates are




thought to provide a better projection of the risk of lung cancer than




absolute risk estimates.  However, both types are included in the set




of risk estimates made below.




     As an alternative to these two models, an age-dependent absolute




risk model with age-dependence somewhat different from that for




natural cancer incidence would also be compatible with the observa-




tions made on uranium miner populations.  It should be noted that the




estimated risks using such a model would be much closer to those



calculated on the basis of relative risk than for an age-independent




absolute risk model.  As yet, parameters for age-dependent lung cancer




risk models have not been published.




     The estimate of the absolute risk due to exposure to radon decay




products in the general environment contained in this report are based




on recent mortality experience of U.S. uranium miners (Na76).




Comparable U.S. data on relative risk are not available, the most




recent relative risk compilation was in 1972 for the NAS-BEIR report

-------
(Na?2).  Since that time, enough new cancers have  occurred  so  that

absolute risk estimates based on this group have more  than  doubled

(Na?6).  The effect of this longer follow-up period  on their relative

risk is unknown, but may be substantial.  Therefore  the estimates of

relative risk made here are based on studies of underground miners  in

Czechoslovakia and Sweden.  Relative risk data for the Ontario miners

have not been published.  However, an oral presentation indicates the

results of the Ontario study (Mi?6) agree with those for  Czech and

Swedish miners (He?8).

     The percent increase in excess cancer per WLM for Czechoslovakian

uranium miners is shown in Table 6.  These data have been recalculated

                                TABLE 6

             OBSERVED INCREASE IN LUNG CANCER FATALITY RATE
                     CZECHOSLOVAKS URANIUM MINERS

    Mean Exposure (WLM)                            % Increase  per WLM

            39                                            3.6*

            80                                            1.0*

           124                                            1.6

           174                                            2.9

           242                                            2.2

           343                                            2.0

           488                                            1.8

           716                                            1.4

*Not significant at the 5% level of confidence
                                   41

-------
from References Se73 and Se?6 on the basis of an assumed nine-year

latent period between the start of exposure and the occurrence of a

radiation-induced lung cancer.  At the exposure levels which occurred

in the Czech uranium miners, the average risk would appear to be

increased by about 2-3 percent per WLM.

     Table 7 shows the percent increase per WLM observed in Swedish

miners (Sn74, Ra?6).  In this case the increase may be as great as 4

percent per WLM at lower levels of exposure.  The variations in the

percent increase in lung cancer found in these epidemiological studies

are not due to statistical sampling variation alone.  Each study

reflects differences in the age distribution of those exposed, the

duration of the exposure, and the follow-up periods.  Given the

variations shown in Tables 6 and 7, the best that can be done is to

propose a range within which the actual risk may lie, as described in

Section 4.1.3.

                                TABLE 7


             OBSERVED INCREASE IN LUNG CANCER FATALITY RATE
                      SWEDISH IRON AND ZINC MINERS

         Mean Exposure (WLM)                   % Increase per WLM

                15                                     4*

                48                                     4.2

               218                                     3.3

               696                                     2.5

*Not  significant at 5% level.
                                    42

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4.1.3  Applicability of Underground Miner Risk Estimates to the
       General Population

     As in most cases where the results of epidemiological studies of

occupational exposures are applied to the general population, there  is

uncertainty in the extent of comparability between the persons at

risk.  Very little information is available on those

non-occupationally exposed.  A recent case control study by Axelson

and Edling (AX79) is suggestive that the mortality per WLM for Swedish

residents in homes having presumably high levels of indoor radon

daughters is comparable to that observed in underground miners.

However, the sample size is small and the exposure estimates too

tentative to allow definite conclusions.

     Since the only common factor in underground miners with increased

risk of lung cancer mortality is exposure to radon and radon daughter

aerosols, the comparability of mine atmospheres, indoor and outdoor,

should be considered.  Jacobi, ejt al.,  (Ja59), studied aerosol

particle size distributions indoors, outdoors, and in radium mines,

finding similar distributions in each place.  Measurements by George

(Ge75a), George, £t aJ., (Ge75b) and others (Ha?6, Lo77, Le75) would

lead to similar conclusions.  Holleman  has also concluded that the

difference between mine and atmospheric aerosol particle distri-

butions was negligible, with the possible exceptions of the immediate

vicinity of diesel engines and remote areas of the mine where aerosol

concentrations were low (Ho68).

-------
     In general,  mine atmospheres are not expected to differ greatly

from environmental atmospheres of the same quality.   Dusty atmospheres

have low, unattached radon-daughter fractions,  clean atmospheres have

high unattached fractions.   Well -ventilated areas have low radon-

daughter ratios,  poorly ventilated areas have high ratios.  There is

no feature which would uniquely identify either mine or environmental

atmospheres, as shown in Table 8.



                              TABLE 8

           Comparison of Typical Aerosol Characteristics

                                        Environment
    Aerosol      Ventilated Mines        Outdoors              Indoors


                     °-"(a'b>0>         O.M-0.30'"         0.10W>
Concentration        107(drilling)(c)

(particles/cm3)     103-106  (c)        lO^-IO5  (a)         104-105  (a'f)


                                                                  (a)
Uncombined           0.04                0.08                 0.07
 Fraction
  (Range)           (0.002-0.12)        (0.005-0.25)         (0.003-0.20)
Radon-Daughter  1.0,1.0,0.4,0.3 (c)  1.0,0.9,0.7,0.7 (a>d) 1.0,0.8,0.8,0.7 (a'd'f)
Ratio Range           to                     to                    to
                1.0,0.3,0.03,0.03    1.0,0.8,0.5,0.3       1.0,0.5,0.3,0.2
References:
     (a)  Ge75a             (d)  Ha76
     (b)  Ge75b             (e)  In73
     (c)  Ge72              (f)  Lo77

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     There are several reasons for believing that the percent  increase



in lung cancer per unit exposure to a general population  could be



either more or less than that for miners.  Alpha particles  from radon



daughters have ranges in tissue comparable to the thickness  of the



bronchial mucus and epithelium.  The thickness of the bronchial



epithelium of underground miners may be greater than is common in  the



general population.  The BEIR Committee estimated that the  shielding



provided by the thicker epithelium of miners reduced their  dose (and



risk) per unit exposure by a factor of two compared to the general




population (Na?2).



     On the other hand, miners' lung cancer mortality data  reflect  a



high frequency of cigarette smoking which tends to increase  their  lung



cancer risk relative to the general population.  The degree  to which



smoking in conjunction with exposure to radon daughters may  increase



the incidence of radiation-induced lung cancer is not known.   While a



study of U.S. uranium miners has suggested a very strong  association



between cigarette smoking and radiation-induced lung cancer, the



correlation between age and smoking history in this study precludes



early judgment, particularly since the study also indicates  that



nonsmokers have a longer latent period for radiogenic lung  cancers



(Ar?6).  Some Swedish data on underground miners show that  smoking  may



increase radiogenic cancers by a factor of about two to four (Ra?6),



however, these results may be dependent on the duration of  follow  up.



Axelson and Sundell (Ax?8) have reported that in a life span study  of



19 exposed miners who died of lung cancer, the lifetime risk of lung

-------
cancer in non-smokers exceeded that of smokers.  The  latency period,



however, was much shorter for smokers.  A sample size this  small,  of



course, precludes definitive judgments.  Unfortunately,  the Japanese



data are, as yet, too imcomplete to yield comparable  risk estimates



for cigarette smokers or non-smokers or even by sex  (Be?7).



     Smoking is common in all populations at risk  from  environmental



radon.  While the frequency of smoking in U.S. uranium  miners  was  not



very different from that of other male industrial  workers at that



time, it exceeds the current level of cigarette use,  particularly  by



females (St?6).  It is not clear that this will be true in  the



future.  Cigarette smoking among younger females is  continuing to



increase and may approach or exceed cigarette  smoking by males.  If



so, relative risk estimates for exposure to radon  daughters based  on



the current incidence of lung cancer mortality, which is now almost



wholly due to male deaths, will be too low.  Conversely, if cigarette



smoking in the U.S. becomes less common for both sexes  sometime in the



future the incidence of lung cancer may decrease and relative  risk



estimates based on the current incidence will  be too high.  Clearly



cigarette smoking is likely to be a factor  in  determining  the  proba-



bility that a lung cancer is induced by exposure to  radon  daughters.



The Agency recognizes that estimates of the risk due to radon  daughter



inhalation have a wide range and may be too high or  too low,  depend-



ing,  among other factors, on the prevelance of cigarette smoking in



the future.

-------
     Based on Tables 6 and 7 and the considerations outlined above,



the range of the fractional increase in lung cancer due  to radon  decay



products in the general environment is thought to lie between one and



five percent per WLM.  Studies utilizing longer follow-up times and



relatively low exposures tend to support the latter figure.  However,



if miners are atypically sensitive to radon daughters because of  other



characteristics in their occupational environment the fractional



increase for the general population could be as low as one percent per



WLM or less.



     Another characteristic of the population at risk that differs



from underground miners is age.  The estimated risk for  miners is



averaged over adult age groups only, children not being  at risk.   It



is assumed in the absolute risk estimates given below that the risk



due to radon daughters is the same for children as adults.  While this



has little effect on the estimates of risk made with an  absolute  risk



model, relative risk estimates are more dependent on the assumed



sensitivity of children to radiation.  The Japanese experience, as



reported in the 1972 BEIR Report, indicates that children irradiated



at the age of nine or less have a relative risk rate of  fatal solid



tumors ten times that of adults (Na72).  However, none of the observed



cancers in this group has been lung cancer, a cancer of  old age.



(There is, of course, no information on lung cancer due  to



occupational exposure of children to radon decay products.)



     The Agency believes that while it may be prudent to assume some



allowance for the extra sensitivity of children, the factor adopted



should be less than a factor of ten. Therefore, in the Tables below, a

-------
three-fold greater sensitivity for children is assumed in some of  the

relative risk calculations of mortality due to inhaled radon decay

products.

     Cumulative exposures for a given concentration of radon daughters

differ between miners and the general public.  For radon decay pro-

duct exposures occurring to nonoccupationally exposed persons,

consideration must be given to the fact that the breathing rate

(minute-volume, etc.) of miners is greater and the number of hours

exposed per month less than in the general population.  Radon decay

product exposures to underground miners are calculated on the basis  of

a working level month (defined as exposure for 170 hours to one

working level).  Exposure to radon daughters in the general environ-

ment occurs for an average of 730 hours per month.  The breathing  rate

over this period of time is less than an average breathing rate

appropriate for underground miners engaged in physical activity.

Assuming that the average underground miner (comparatively few of  whom

work at the mine face) is engaged in a mixture of light and heavy

activity throughout the working day, his monthly intake of air on  the
                   c
job is about 3 x 10  liters (In 75).  An average man  (reference  man)
                             n                                   ii
is assumed to inhale 2.3 x 10  liters per day (males) or 2.1 x  10

liters per day (females) (In 75).  The average intake for both sexes
           c
is 6.7 x 10  liters per month, 2.2 times more than for miners at

work. Therefore, an annual exposure to 1 WL corresponds to nearly  27

WLM for exposures occurring in the general environment.

     In the case of radon in residential structures,  the time the

residence is occupied must be considered also.  On the average,

-------
Americans spend about 75 percent of their time in their place of

                                     5
residence (Mo?6) so that about 5 x 10  liters of residential air  is


inhaled each month.  This corresponds to about 20 WLM per year  for a


radon decay product concentration of 1 WL in residential structures.


Children respire a greater volume of air relative to the mass of


irradiated bronchial tissue than do adults, so that their exposure to


radon daughters is almost a factor of two greater for a few years


(In75).  This increase has been included in the Section 4.1.4 risk


estimates.




4.1.4  Risk Estimates for the General Public


     Estimates of cancer risk in this report have been derived  from an


analysis that considers the following factors: the competing risk from


causes of death other than radiation, the fractional and absolute


increase in lung cancer per unit exposure, the duration of the  expo-


sure, the period between the time of exposure and the occurrence  of a


clinically identifiable cancer (latency), and the length of time  a


person is at risk following the latent period (plateau period)  (Bu78).


The risk estimates below assume a fixed latent period of 10 years for


lung cancers (Na76).  Although there may be some correlation between


latency and age, relative risk estimates are not too sensitive  to this


parameter.  Increasing the latency period to 30 years reduces the


estimated risk by between 20 and 40 percent depending on the sensi-


tivity assumed for children.  In the case of lung cancer, it is


assumed that following the latent period an individual remains  at risk


for the duration of his or her lifetime.  While for some cancers  a
                                   49

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shorter plateau at risk may be appropriate, the U.S. miner data as




well as the Japanese bomb survivor data reflects a continuing  increase




in radiogenic lung cancers beyond 70 years of age.




     In these risk estimates it is assumed that the population at risk




is subject to lifetime exposure and the distribution of ages is that




in a stable (stationary) population (Un?5).  The Agency recognizes




that residential dwellings are seldom occupied by one  family group  for




their lifetimes. However, this has little effect on the ultimate




health impact if another family occupies the structure.   The health




risk to a particular family is a function of the time  they occupy  the




dwelling and to a lesser extent their ages.  For most  practical pur-




poses, the risk due to occupancy of less than 70 years can be  found by




taking a fraction of the risk given below as proportional to the years




of occupancy.  For example, 7-year occupancy would  be  expected to




yield one-tenth the estimated risk of lung cancer due  to  lifetime




exposure, approximately 70 years.  Residences which serve primarily as




children's or geriatrie's homes would be obvious exceptions.



     The excess cancers due to radiation change  the cause of death and




the age at which death occurs in the population  at  risk.  The  EPA




analysis provides estimates of the number  of premature deaths, the




number of years of life lost per excess  death,  and  the total number of




years of life  lost by  the population at  risk.   These  parameters are




included in  the risk estimates presented below.




     Based on  the assumptions discussed  above,  Table  9 lists  the




estimated number of premature fatalities  due  to lung  cancer that may
                                    50

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occur in a population of 100,000 persons occupying structures having a

radon decay product concentration of 0.02 WL.  The total number of

years of life lost by the population at risk is also tabulated.  These

estimates are based on relative risk models which assume a 3 percent

increase in lung cancer per WLM.  Two cases are compared in this

Table: (1) that adults and children have the same sensitivity, and  (2)

that children below the age of ten are three times more sensitive than

adults.  It is seen that the latter assumption increases the estimated

risk by about 50 percent.

                                 Table 9

      Estimated Risk of Lung Cancer Per 100,000 Exposed Individuals
            Due to Lifetime Residency in Structures Having an
                 Average Radon Daughter Concentration of
                       0.02 WL Relative Risk Model*

                              Excess Cancer Deaths   Total Years Lost

Child Sensitivity = Adult              2,000              30,000
Child Sensitivity = 3 x Adult          3,000              50,000


     •Assumed mortality 3 percent per WLM (see text)


     Table 10 presents absolute risk estimates for a radon decay

product concentration of 0.02 WL and lifetime exposure.  This Table

has been calculated on the assumption that absolute risks are

independent of the age at which exposure is received.  The estimate of

the number of years of life lost, compared to the relative risk for

the same age sensitivity, is about the same, c.f. Tables 7 and 8.   The

estimated number of excess fatalities is a factor of two less than

that estimated using the relative risk model.  This is within the
                                   51

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uncertainty of the relative risk estimates since the range of values

for the percent increase in lung cancer per WLM is between 1 and 5

percent per WLM, vis a vis the 3 percent increase assumed in Table 10.

                                Table 10

     Estimated Risk of Lung Cancer Per 100,000 Exposed Individuals
       Due to Lifetime Residency in Structures Having An Average
                Radon Daughter Concentration of 0.02 WL
                          Absolute Risk Model*

                                Excess Cancer Deaths   Total Years
Lost

Child Sensitivity = Adult              1,000                 27,000

     *The assumed risk coefficient is 10 excess lung cancer deaths
      per WLM for 10^ person years at risk (Na 76).


     For comparison purposes, it is of interest to estimate the number

of excess lung cancers in the U.S. due to ambient levels of radon

decay products in non-contaminated areas.  The concentration of radon

decay products in structures has not yet been surveyed extensively.

Most measurements reported in the literature are for either a short

duration, i.e., single samples, or in contaminated areas.  An excep-

tion is the long-term radon measurement program of the Environmental

Measurements Laboratory in the Department of Energy.  Their measure-

ments of radon decay products indicate average background levels in

residences of 0.004 WL (Ge 78).  An ambient indoor background of this

level yields calculated risks one-fifth of those shown in Table 9,

i.e., from about 400 to 600 cases.  This is about  10 to 20 percent of

the expected total  national lung cancer mortality  of 2900 per  100,000

in a stationary population having the 1970 U.S. mortality rates.  This
                                    52

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percentage of lung cancer mortality is not necessarily  attributable to


radon exposures alone, since many oofactors have been implicated  in


the etiology of lung cancer.  It is emphasized  that  these  risk  esti-


mates are not precise and that the actual risk  from  radon  daughter


exposures could be a factor of two or more larger  or smaller.


     It should also be noted that the risk estimates made  here  are


based on a risk analysis using U.S. national health  statistics.   They


have not been adjusted for the age, sex, or other  demographic factors
      N

pertinent to persons living on phosphate lands  in  Florida.  To  the


extent that the incidence of lung cancers in these areas is higher by


about 40 percent than the national average, the estimated  health


impact of radon exposures given above may be low in  Florida


residents.  In contrast, the persons living on  phosphate lands  could


have demographic characteristics which differ from the  national


average in such a way as to lower their risks compared  to  those listed


above.  For example, if the housing were used primarily by the  very


old, there would be appreciably less health impact.




4.2  The Health Risk Due to External Radiation  Exposure


     Unlike the highly ionizing alpha particles from radon daughters,


external radiation exposures are due to lightly ionizing secondary


particles from interactions along the path of gamma-ray penetration.


High energy gamma-rays penetrate through the body  causing  a relatively


uniform exposure to all tissues and organs.  Since all  organs and


tissues are exposed, the complete spectrum of cancers outlined  in the
                                   53

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1972 NAS-BEIR Report (Na72) would be expected.  In addition, some

genetic risk, resulting from irradiation of the gonads, would be

expected to occur.

     In the case of external penetrating radiation, data presented in

the 1972 NAS-BEIR Report (No 72) yields the following estimates for

lifetime whole body exposure to 100,000 persons as shown in Table 11.


                                TABLE 11

      Estimated Lifetime Risk of Excess Fatal Cancer and Genetic
             Abnormalities Per 100,000 Individuals Exposed
                   to an Annual Dose Rate of 100 mrem

                      Excess Fatal Cancers         Total Years Lost

                              470 a)                     6500 a)
  Relative risk               150 b)                     2700 b)

                               84 a)                     1900 a)
  Absolute risk                68 b)                     1700 b)

   a) life time plateau                 b) 30 year plateau

                    Serious genetic abnormalities*
                                                     all succeeding
                           1st generation             generations

                                 2-40                    10-200

•Birthrate 2% per year


     These estimates are based on the assumption that the number of

health effects observed at relatively high doses and dose rates can  be

extrapolated linearly to the low levels of radiation usually found in

the environment.  Table 11 lists only fatal cancers.  The 1972 NAS-

BEIR Committee has estimated that a comparable number of non-fatal

cancers could be  induced also.
                                    54

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     External exposure to natural background radiation in Florida,




from both cosmic radiation and radiation from radioisotopes present in




the soil, is about 59 millirem per year, except in regions containing




anomalous sources.  The estimated lifetime risk associated with this




background is therefore about 60$ of the values listed in Table 10.
                                   55

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                              SECTION 5.0

                    ANALYSIS OF CONTROL ALTERNATIVES



5.1  SUMMARY OF AVAILABLE CONTROL MEASURES*

     There are five major types of radon decay product control

measures.  These are categorized in Table 12 as to their efficacy  for

application to existing or planned structures.  For existing

structures, air cleaners and polymeric sealants have  been  shown  to be

efficient at either reducing radon decay product levels in the

structure or radon diffusion through the foundations, respectively.

The cost range for these measures is $900-2600 (assuming an average

cost of $1200 for sealant application).  These cost values are based

on the sum of capital cost, plus future maintenance charges and

operational costs reduced to their present worth, the discount factor

being 6 percent per year over 70 years, the assumed lifetime of  the

average structure.  For planned structures, design measures could

include ventilated crawl spaces, excavation and fill, and  improved

slab construction.  As a result of these measures, radon diffusion can

be reduced before it enters the structure's atmosphere by  venting  or

reduction of the parent radium concentration.  Total  costs for

implementing these measures vary from $550 (for crawl space

construction) to $5500 (for excavation and fill).  As these are  all
     A more detailed treatment of  the  subject  can  be  found  in
Appendix C.

                                   56

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                                             TABLE 12
                     ESTIMATED AVERAGE COST OF CONTROL MEASURES FOR
                   STRUCTURES CONSTRUCTED ON FLORIDA PHOSPHATE LAND*
(Jl
~J
CONTROL MEASURE
EXISTING STRUCTURES
AIR CLEANERS:
HEPA
ELECTRONIC
ELECTRONIC AND AIR EXCHANGER
POLYMERIC SEALANT-
PLANNED STRUCTURES
VENTILATED CRAWL SPACE:
EXCAVATION AND FILL:
(TO 10' DEPTH)
COMMERCIAL FILL RATE -
FOR 80% RADON REDUCTION (INCLUDES 99%
GAMMA)
FOR 80% GAMMA REDUCTION
W/NOMINAL FILL COST -
FOR 80% RADON REDUCTION (INCLUDES 70%
GAMMA)
FOR 80% GAMMA RED
IMPROVED SLAB CONSTRUCTION:
FOR 80% RADON REDUCTION (INCLUDES 70%
GAMMA)
FOR 80% GAMMA REDUCTION
CAPITAL
COST

$400
$350
$900
S600-S1950
$550


$3250-$5500
$250 -$400

$2550-$2900
$200

$550
$600
ANNUAL
MAIN-
TENANCE
COST

$100
$25+ ***
$25+
UNDEFINED
NONE


NONE
NONE

NONE
NONE

NONE
NONE
ANNUAL
ELECTRICAL
COST

UNDEFINED
$10
$80
NONE
UNDEFINED


NONE
NONE

NONE
NONE

NONE
NONE
TOTAL
AVG. ANNUAL
OPERATING
COST

$100
$35+
$105+
NONE
NONE


NONE
NONE

NONE
NONE

NONE
NONE
PRESENT
WORTH Ol
TOTAL COST
(70 YRS)

$2050
$900
S2600
S600-S1950
$550


S3250-S5500
S250-S400

S2550-S2900
$200

$550
$600
        "ASSUMMING 1500 SQUARE FEET FLOOR AREA AND 1977 DOLLAR VALUE (6% DISCOUNT PER YEAR APPLIED) ALL FIGURES ARE FOR RADON
        PROGENY REDUCTION EXCEPT WHERE OTHERWISE NOTED
      **SEE TEXT
      ***"+" SIGNIFIES THAT THE ESTIMATE GIVEN IS MOST LIKELY A MINIMAL ONE ALTHOUGH THE ACTUAL AVERAGE IS UNDEFINABLE USING
        AVAILABLE COST DATA

-------
passive measures (i.e., having no maintenance or operational




requirements), the total cost involved consists solely of the capital




cost of implementation (although there may be minor exceptions such as




additional heating cost due to increased infiltration of air and heat




conduction through the floor for a crawl space compared to an on-grade




slab).




     The control measures listed in Table 12 have been field tested on




a limited basis in a number of locations in this country and Canada.




In the Grand Junction (Colorado) remedial program, for example,




sealants, excavation and fill, and electrostatic precipitators were




used to reduce indoor radiation levels pursuant to the Surgeon




General's Guidelines (see page 77).  While the latter two methods




achieved reduction efficiencies at or near 80 and 40 percent,




respectively, results from application of sealants proved




inconsistent.  Experience by the Canadian authorities (At78, Fi78) in




applying sealants to structures constructed on radium-contaminated




soils, however, suggests that this lack of consistency in achieving




desired reduction is likely due to inadequate sealing of existing




conduits for radon into the structure's atmosphere.  Their objective



of achieving indoor radon decay product level reduction down to  .02 WL




(including background) was largely met by a combination of sealant




application and removal of these major radon pathways in the




foundation.
                                    58

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     Although none of the radon decay product measures have been field




tested in Florida, on the basis of their demonstrated efficiencies in




these field programs, all of these measures should have an efficiency




of about 80 percent, with the exception of electronic air cleaners




(HO percent), when employed in normally ventilated structures.  The




lack of field confirmation is a drawback in determining the




cost-effectiveness for each control.  Regardless of this uncertainty,



however, the cost figures are considered representative and permit a




preliminary evaluation of cost-effectiveness.




     Control of gamma exposure in existing structures requires either




the addition of shielding or removal of the radium source from under




the structure.  Both of these procedures are quite expensive, with an




estimated cost of 15 to 20 thousand dollars per structure.  For gamma




exposure reduction in planned structures, improved slab construction




(i.e., additional slab thickness) should be about 80 percent effective




for an additional four inches of concrete at an average cost of about




$600.  However, if clean fill at minimal or no cost is available, a



comparable reduction in exposure may be possible at lower cost.








5.2  COST-EFFECTIVENESS




     Control cost-effectiveness is defined as the ratio of the present




worth of the cost of control to the reduction in health risk




anticipated.  The upper limit of acceptable cost-effectiveness is a




value judgment on the maximum rate of spending that is justified for
                                   59

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averting human health effects.  While a detailed discussion of this




issue is outside the scope of this document, such determinations have




been made in other guidance issued by the Federal government.  In the




Uranium Fuel Cycle Standard (40CFR190), for example, a limit on




reasonable cost-effectiveness ranging from $200,000-500,000 per health




effect averted was used.  While not necessarily applicable to the




Florida case, this example provides some perspective concerning




reasonable limits on acceptable values of cost-effectiveness.








5.2.1  General




     As previously noted, two general categories of remedial measures




are involved: those for existing structures which have been




constructed on radium-bearing soil and those for structures which may




be so sited in the future. These are important distinctions (as




discussed further in Appendix C) because different types of controls




have different costs and effectiveness depending on whether they are



applied prospectively or retrospectively.  Therefore, this examination




of control cost-effectiveness is divided into four parts: radon decay




product controls for existing structures, radon decay product controls




for new structures, external gamma exposure controls for existing




structures, and external gamma exposure controls for new structures.




     In making estimates of the cost-effectiveness of various control




technologies, the following assumptions were used:




     1)  The average dwelling has 1500 square feet of slab foundation.
                                   60

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     2)  It is occupied 75 percent of the time by a statistical




         average of 3^5 people.




     3)  Control costs are summed for a 70 year period, the assumed




         lifetime of the structure.  While this may not be quite




         appropriate for existing structures, it does not




         significantly change the results because the costs of most




         controls are dominated by their capital cost.  Further,  the




         present worth of any annual costs beyond 20 or 30 years




         becomes negligible.








5.2.2  Control of Radon Decay Products




     As previously estimated, the "normal" background radon decay




product level in a Central Florida dwelling is about .004 WL.  A




structure which exhibits an indoor radon decay product concentration




of .030 WL is thus about .026 WL above normal.  The discussion on




control technology effectiveness in Appendix C indicates that an




average 80 percent reduction in the average indoor radon decay product




level could be attained using one or more of the control methods



listed.  For this assessment it is assumed that the 80 percent




reduction only applies to radon decay product air concentrations  in




excess of "normal" background.  In many cases "normal" background




radon decay product concentrations would probably also be reduced by




applying these controls, but such potential reductions are not




included in this evaluation of cost-effectiveness.  If they were  to be
                                   61

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included they would tend to decrease the resource expenditures per



health effect averted, making the application of the control more



cost-effective.



     Applying remedial measures to a structure exhibiting an average



indoor radon decay product air concentration of .026 WL above normal



(0.03 WL gross)  is estimated to typically result in reducing the



average concentration to about .005 WL above normal (.009 WL gross).



The cost-effectiveness of taking this control action (based upon the



health risk estimates in Section 1) is estimated as follows:



         estimated risk of lung cancer per  100,000 exposed due to



         lifetime residency at .03 WL = 3000 premature deaths  (child



         sensitivity = adult)



         estimated risk of lung cancer per  100,000 exposed due to



         lifetime residency at .009 WL = 900 premature deaths  (child



         sensitivity = adult)



     Therefore, by reducing the level from  .03 to  .009 WL, an



estimated 2100 lung cancer cases per  100,000 exposed are  avertable.



This is normalized to one structure assuming an average  occupancy  of



3.5 individuals to yield  .074 averted lung  cancer  cases  per  structure.



     From Table 12, the cost for controls ranges  from  $900  to  $2600



per structure.  Therefore, the cost-effectiveness  is:






         $900-$2600/structure           _  $12,000  to $35,000 per
 .07^  premature  deaths  averted/structure      premature death averted
                                    62

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     The above analysis was performed for various indoor radon decay




product concentrations for both existing and proposed structures,  (the




latter at a projected cost of $550 per structure), and graphed in




Figure 8 for both initial and achieved indoor radon decay product




levels.  For both categories of structures, it is apparent that




cost-effectiveness approaches unreasonably high values asymtotically




at roughly the .01 WL control level.  For higher indoor




concentrations, the calculated cost-effectiveness is generally




favorable.








5.3.3  Control of External Gamma Exposure




     Average outdoor gamma radiation exposure rates measured around




the dwellings studied ranged from 3 to 42 yR/h (26 to 370 mrem/year).




Average indoor gamma radiation exposure rates for these structures




ranged from 3 to 27 yR/h (26 to 240 mrem/year).  Due to the shielding




effectiveness of the materials used in the construction of these




structures, most of them exhibited lower average radiation exposures




rates indoors than outdoors. The principal shielding element




contributing to this effect is the concrete used in the slab



foundations and the masonry walls.  Other factors influencing the




ratio of indoor to outdoor exposure include: 1) at lower external




radiation exposure rates (5 to 9 yR/h), much of the exposure is not




readily reducible by adding floor shielding because of the cosmic  ray




component and the scatter from the ubiquitous normal radioactive
                                   63

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Q
01
P
ill
LL
Li-
La
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                                           Figure 8

        COST-EFFECTIVENESS OF REMEDIAL ACTION TO REDUCE INDOOR RADON

             DECAY PRODUCT LEVELS FOR EXISTING AND PLANNED STRUCTURES
     60
     50
     40
30
20
     10
      EXISTING

(S900-2600/STRUCTURE)
                      PLANNED

                   ($550/STRUCTURE)
                                                           I
       0        0.01        0.02        0.03       0.04       0.05        0.06       0.07

        CONCENTRATION LEVEL AT WHICH REMEDIAL ACTION IS INITIATED (IN WORKING LEVELS )

                0.005       0.007       0.009     0.011       0.013       0.015       0.017

            CONCENTRATION LEVEL ACHIEVED BY REMEDIAL ACTION (IN WORKING LEVELS)

-------
surroundings, and 2) the construction material may contain significant




concentrations of radioactivity which would offset any shielding




reduction.



     Precise calculation of the exposure reduction expected due to




control measures, such as additional slab thickness or removal of




contaminated fill under a structure, is complex.  It depends upon the




geometry of the structure, its material makeup, and the radioactive




environment, all of which can be approximated using a general model.




     Because the cost of achieving control of gamma exposure in




existing and new (or prospective) structures is vastly different, two




separate evaluations need to be performed.  In estimating the control




cost-effectiveness for new structures, the following general




assumptions were used:




     1.  The structure type in question is slab-on-grade.




     2.  The normal external gamma radiation exposure rate is 6 uR/h.




     3-  The impact of shielding, specifically concrete, on exposure



         reduction was taken from Figure 9 (SC 71*).




     4.  Practical control cannot reduce the exposure rate to below




         normal background (primarily as a result of unshielded



         contributions through the structure walls).




     5.  The reduction factors are applied only to the difference




         between the normal background and unshielded exposure rates




         in computing the impact of shielding.




     While these assumptions lead to a simplistic model, there does




appear to be sufficient agreement with the field data collected for
                                   65

-------
       1.0
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                           PACKED EARTH
        ORDINARY CONCRETE
            (G% POROSITY)
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         0      4      8      12      16      20
             THICKNESS OF SHIELDING (Inches)
                                            24
FKJUK;  9.  REDUCTION OF GAMMA EXPOSU RE  RATE RESU LTING
          FROM EARTH OR CONCRETE SHIELDING (Sc 74)
                             66

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slab-on-grade structures throughout the Central Florida  study  area  as




discussed in Appendix D and graphed in  Figure  10.  This  is




particularly true of structures originally exhibiting  outdoor  gamma




exposure rates greater than 15 yR/hr.  Therefore, it is  anticipated




that adding sophistication to the model would not markedly improve  the




usefulness of the analysis for decision making.




     For new structures, the cost-effectiveness of controlling




external gamma exposure is estimated as follows for a  structure  that




is assumed to have an unshielded (i.e., external) exposure rate  of




40 yR/h:




        - A structure with a 4 inch shielding slab is  estimated  to




          have a gamma exposure reduction factor of 0.35  (Figure 9);




          therefore, the (model) residual indoor exposure is:




                (40 - 6) yR/h x 0.35  +6 yR/h  = 18 yR/h




Therefore, the net reduction is:




                (40 - 18) yR/h  = 22 yR/hr;




which, assuming 75 percent occupancy, 3-5 persons per  structure  and a




mean lifetime exposure period of 70 years is equal to  approximately



600 fatal health effects per 100,000 population (relative risk




model).  Assuming a control cost of $550 for a typical 4" concrete




slab, the cost-effectiveness is:
                               $550
                  6x10~3 health effect averted



                            = $28,000 per health effect averted
                                   67

-------
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                                                   Figure 10

         CORRELATION OF OBSERVED INDOOR GAMMA EXPOSURE WITH THEORETICAL ESTIMATION



                                                                          LEGEND: A = 1 DBS, 8=2 DBS, ETC.
                 I
                          I
                                   I
                                                                                                A  A
       ,,                  d        9        10        11        12        13        M        16        16



    f-TM\1A|iD ll\noOH GAMMA EXPOSURE (juR/h) (3ASED ON BACKGROUND  6juR/h AND REDUCTION FACTOR OF 0.35 foi 4" CONCRETE SLAB)

-------
     This calculation has been performed for several cases  involving




both new and existing structures.  The results of these calculations




are graphed in Figure 11 (a, b, c, d, e).  The three levels of  control




for the cases described in Figure  11 (a, b, c) are successive 4"



additional depths of concrete in the foundation, which is the least




expensive control measure.  Therefore, Level I (Fig. 11a) is the




normal slab thickness of H inches, Level II (Fig. 11b) is a total  of  8




inches, and Level III (Fig. 11c) is a total of 12 inches of ordinary




concrete.  The cost-effectiveness  for controlling gamma exposure in




existing structures (Fig. lid) is based on excavation and filling  with



clean dirt in and around the structure's foundation, at a cost  of




$15,000 per structure as derived from the Grand Junction remedial




program (Co?8).  A summary of cost-effectiveness for controlling




indoor exposure in both planned and existing structures is  provided in




Figure 11e.




     In controlling gamma exposure, some reduction in indoor radon




decay products levels might also be achieved.  However, because of the




difficulty in reliably predicting  such effects the cost-effectiveness




estimates do not take them into account.  While it is anticipated  that




radon decay product levels would generally be the primary factor in




determining if radiation control is warranted, it would be  prudent,




particularly in new structures that require preventative measures  and




where acceptable radon decay product control can be achieved by a




number of means, to consider measures which can minimize both
                                   69

-------
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                                              Figure 11a
    COST-EFFECTIVENESS OF EXTERNAL GAMMA EXPOSURE CONTROL FOR PLANNED STRUCTURES
                          (ASSUMING 4" CONCRETE SLAB CONSTRUCTION' $550)
1200
    1000
    800
    600
 400
     200
               Q
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           D
          RESULTING

           LEVELS

         (ESTIMATED)
                          10
                                 15        20        25        30


                                UNSHIELDED GAMMA EXPOSURE RATE (juR/h)
                                                                           35
40

-------
                                               Figure 11b

  COST-EFFECTIVENESS OF EXTERNAL GAMMA EXPOSURE CONTROL FOR PLANNED STRUCTURES

                        (ASSUMING 8" CONCRETE SLAB CONSTRUCTION@$1,500)
    1200
 DC
 LU
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     800
600
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RESULTING

  LEVELS

(ESTIMATED)
                                        a
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                                        J.
                                        J.
       0


       0
                      10


                      5
           15
20
25
                                   30


               10                   15

UNSHIELDED GAMMA EXPOSURE RATE (juR/h)
35
40 |  INITIAL

 20 j  RESULTING

-------
                                             Figure 11c
COST-EFFECTIVENESS OF EXTERNAL GAMMA EXPOSURE CONTROL FOR PLANNED STRUCTURES
                    (ASSUMING 12" CONCRETE SLAB CONSTRUCTION@$4,000)
  12001-
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                        10
                        5
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          10                  15
 UNSHIELDED GAMMA EXPOSURE RATE (juR/h)
                                                                        35
40
20
INITIAL
RESULTING

-------
                                             Figure 11d

COST-EFFECTIVENESS OF EXTERNAL GAMMA EXPOSURE CONTROL FOR EXISTING STRUCTURES

                            (ASSUMING EXCAVATION AND FILL<*$15,000)
    3 2400
    cc
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                     RESULTING

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                    (ESTIMATED)
                                                     INITIAL LEVELS
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                                    UNSHIELDED GAMMA EXPOSURE RATE (xiR/h)

-------
0  1200
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                                             Figure 11e
              COST-EFFECTIVENESS OF EXTERNAL GAMMA EXPOSURE CONTROL
                             FOR EXISTING AND PLANNED STRUCTURES
                                            (SUMMARY!
   800
   600
CO
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"J  200
                                                                      EXISTING (EXCAVATION

                                                                      AND FILL @S15000)
                                                                                         IV
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                                                     I = 4" CONCRETE SLAB @ $550
                                                     II = 8" CONCRETE SLAB @ S1500
                                                       = 12" CONCRETE SLAB @S4000
                                                                                        •a I
                          10         15        20        25         30

                              UNSHIELDED GAMMA EXPOSURE RATE (>uR/h)
                                                                             35
40  INITIAL

-------
radiation exposure components.  An example is excavation  and  fill  (for




planned structures), which would remove both the  source term  for




radon-222 diffusion and gamma radiation.




     In conclusion, assuming that it  is reasonable  to  spend about




$200,000 to $500,000 to avert a health effect such  as  death or  serious




genetic damage (Un76), it appears from Table 12 and Figure 8  that  it




is cost-effective to apply most control technologies to reducing the




indoor radon decay product levels in  new and existing  structures from




levels at .005 WL above normal background  (.009 WL  gross) or  higher.




In some cases it may even be cost-effective to apply radon control




technology at indoor radon decay product levels less than  .005  WL




above normal background.  However, this depends greatly on specific




sites and structures and a case-by-case review is required at such




levels.




     In examining cost-effectiveness  for control  of gamma exposure,




review of Figure 11 suggests that in  new structures, Control  Level I




is cost-effective for initial gamma exposure rates  greater than  H  uR/h




above normal (10 yR/hr gross), Control Level II is  cost-effective  for




rates greater than 14 yR/h above normal (20 yR/h  gross), and  Control




Level III is cost-effective at rates  greater than 24 yR/h (30 yR/h




gross).  For existing structures,  review of Figure  11  indicates  that




it does not appear to be cost-effective to retrofit  structures with




control measures solely to reduce external gamma radiation exposure.
                                   75

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                              SECTION 6.0


                 ALTERNATIVES FOR RADIATION PROTECTION





6.1  EXISTING RADIATION PROTECTION GUIDANCE


     At present there are no Federal radiation protection guidelines


specific to radon daughter levels in structures.  Recommendations  of

                                    «
the former Federal Radiation Council  published  in  1960  estab-


lished annual guides for exposure of the whole body of 500 mrems  to an


individual in the general population and 170 mrems  to an average


member of critical population groups.  The Council  further noted  that


"every reasonable effort should be made to keep  exposures as  far  below


this level as practicable."  However, these limits  excluded natural


background radiation, and it is not clear whether or not they were


intended for application to situations in which  man has  artificially


increased this natural background.


     Another potentially relevant Federal guide  is  the U.S. Surgeon


General's Guidelines for remedial action in Grand Junction, Colorado


(Pe?0).  These guidelines, given below, were developed in  1970,  for


use in establishing remedial action criteria for structures having


uranium mill tailings under or around them.
*When the Environmental Protection Agency was  established  by
Reorganization Plan No. 3 in 1970, the  functions  and  authority of the
Federal Radiation Council were vested in EPA.
                                    76

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                     SURGEON GENERAL'S GUIDELINES:

        RECOMMENDATIONS OF ACTION FOR RADIATION EXPOSURE LEVELS
       IN DWELLINGS CONSTRUCTED ON OR WITH URANIUM MILL TAILINGS
External Gamma Radiation

         Level

Greater than 0.1 mR/hr

From 0.05 to 0.1 mR/hr

Less than 0.05 mR/hr


Indoor Radon Daughter Products

        Level

Greater than 0.05 WL

From 0.01 to 0.05 WL

Less than 0.01 WL
        Recommendations

Remedial action indicated

Remedial action may be suggested

No action indicated
       Recommendations

   Remedial action indicated

   Remedial action may be suggested

   No action indicated
     The Surgeon General's Guidelines apply specifically to dwellings

constructed with or on uranium mill tailings, and as noted when they

were issued, should not be interpreted as being applicable to other

cases.  Since these guidelines were developed, additional information

has become available regarding the risk associated with exposure to

radon decay products.



6.2  BASIC RADIATION PROTECTION PRINCIPLES

     For the purpose of developing radiation protection recommenda-

tions for acceptable indoor radiation levels of radon decay products,

the most realistic basis for health risk estimates is epidemiological
                                   77

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studies of groups previously exposed to elevated levels of radon decay




products.  A linear nonthreshold dose-effect relationship has been




assumed to be a prudent model for deriving risk estimates for the




general public from these data, in the absence of contrary infor-




ation.  This assumption implies that there is some risk to humans no




matter how small the amount of absorbed radiati.on and that the risk at




low dose levels is directly proportional to that observed at higher




doses.  In judging the acceptability of such risks, it must be




considered that all persons are exposed to a large number of competing




risks, including other radiation risks, and any reduction of risk from




a single source must be viewed in the overall perspective of the




social and economic impacts involved.  The assumption that any expo-




sure to low level ionizing radiation has some degree of associated




adverse health effects is reflected in guidance issued by the Federal




Radiation Council (FRC) in I960 (Fe60) that any necessary exposure




should be reduced to "as low as practical" (ALAP) levels.  This




guidance also recommends that any planned exposure above zero (or




background) be justified on the basis of a benefit which, as a




minimum, balances the risks associated with the exposure.  Since the



benefits of residence in a particular location or in a specific




structure cannot be quantified on a generic basis (if, indeed, they




can be assessed at all) this latter guidence is not addressed here.




The ALAP criterion was addressed on the basis of an examination of the




cost-effectiveness of control, in terms of dollars per health effect




averted.
                                    78

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6.3  ALTERNATIVES FOR RADIATION PROTECTION




     A number of alternatives are available, both  for  the  form  of




radiation protection recommendations and alternative levels  of  con-




trol.  Consideration of administrative alternatives  (as  opposed to




alternative criteria levels), e.g., no action or delayed action,




however, are not addressed as they are not within  the  scope  of  this




discussion.  It should be emphasized that the control  levels discussed




in this section are provided as examples and do not reflect  all of the




options possible.




     Three basic alternatives bearing on the level and degree of




control may be considered.  In summary, these are:




     1.  Define a nationally applicable level of unacceptable




continuous radon daughter exposure based on consideration  of the




acceptability of the health risk, with remedial measures also taken




below this level, whenever reasonable, based upon local  determinations.




     2.  Define an upper control limit for structures  built  on



phosphate land in Florida based upon two considerations: 1)  the




improvement judged reasonably achievable using remedial  measures for




the majority of cases in Florida, and 2) a judgment of the unaccept-



ability of the health risk above this level.  Define a lower limit




based upon practical limitations of uncertainty in background,  and the




effectiveness of remedial measures, below which no consideration  of




remedial action is recommended.  Between these limits, the imple-




menting authorities would be advised to assess the practicability of




specific remedial measures on a case-by-case basis.
                                   79

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     3.  Define a lower limit only, below which consideration of




remedial action is not recommended.  Above this level, remedial




action, justifiable on the basis of available cost-effectiveness




information, would be taken.  The degree of control warranted would be




determined on a case by case basis taking into account such factors as




cost and effectiveness of available remedial measures, the lifetime




risk averted, the normal background level, the life expectancy of the




structure, and measurement uncertainties.




     The principal obstacle to establishing a national recommendation




(first alternative) is limited knowledge of national radon levels.




This makes it difficult to predict, on either an absolute or relative




basis, what levels can be achieved reasonably or the scope of the




public health problem.  In addition to variation in air leakage rates




of structures with climate (this variable can have a profound effect




on radon levels), new potential radon problems are still surfacing.




The phosphate situation, itself, was only recently uncovered.  Within



the last year, newly identified comparable situations have been




identified arising from thoron, an analogue of radon from thorium




deposits present in monazite sands in Georgia and to a small degree,



in parts of Florida.  The magnitude of the potential health risk




associated with chronic exposure to radon decay products at levels




observed on phosphate lands in Florida appears to justify action




independent of consideration of guidance development on a national




level.
                                    80

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     Alternative 2 contemplates a lower bound for consideration  of



remedial action which would reflect practical limitations  on



measurement and the effectiveness of remedial action and an upper



level above which remedial action would be mandatory.  This lower



bound to ALARA lies approximately at the 0.005 WL (above background)



level, on the basis of experience with such measurements and



cost-effectiveness of available remedial measures developed in this



study (see Figure 8).  The major advantage of this  option  is  its



underlying recognition that, given the limitations  of  technical



information currently available on radon levels in  residences, costs



of remedial action, and the efficacy of remedial measures, it is



desirable to define a reasonable range of flexibility  within which



local authorities can address these uncertainties.  This flexibility



may also be of importance to individual homeowners  who, after



consideration of the reasonableness of reducing their  risk, may  decide



to take more or less action than called for by strict  cost-



effectiveness considerations alone, due to personally  overriding



considerations such as their age, the remaining period of  usefulness



of the structure, and their ability to pay for the  incorporation of



control measures.



     An upper bound criterion level above which remedial action  would



be mandatory should be based on a balancing of health  risk



considerations and the estimated reasonableness of  the costs of



control action to bring indoor radon decay product  concentration in



the worse cases down to at least this level.  As a  function of the
                                   81

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level selected, there may be a significant fraction of structures




which will not be remediable to a sufficient degree to satisfy such a




level.  For these particular structures, the options would be few,




consisting probably of either forced abandonment or the application of




non-cost-effective remedial action.  This inherent disadvantage of a




mandatory criterion, can be minimized if the level chosen can be




projected to be attainable at reasonable cost in all or nearly all




cases.




     The overall shortcomings of this alternative, like the advan-




tages, are inherent in the implementation of ALARA.  Because its




implementation within the specified range would be left to the




discretion of local authorities or the homeowner, there is the




possibility that ALARA will be implemented incorrectly or not at all.




While education on the subject and government advice might reduce the




instances of misuse, the only means to assure implementation would be




to remove the flexibility provided by two levels.  It is also possible




to recommend that remedial action be mandatory within this range with




the degree of control to be applied at the local authorities or the




homeowner's discretion.  Despite public education and assistance in




making determinations as to the level of control at which ALARA is




satisfied for individual cases, implementation could still be highly




variable, depending on factors such as the individual's ability to




afford control measures, their ability to comprehend the risk and the




"cost-effectiveness" of control involved, and the extent to which




assistance is available from local authorities.
                                   82

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     Alternative 3 is an option under which  the  implementation  of




remedial action would be called for at  all indoor  radon  decay product




levels, above a minimum level, whenever reduction  is  reasonably




achievable.  All of the difficulties present  in  the range  between the




two levels provided by Alterntive 2 would apply  to the whole range of




levels that fall above the single level provided in this Alternative.




In many situations observed in Florida  it would  be desirable and




practical to reduce the chronic exposure to  radon  decay  product levels




to considerably less than an upper bound criterion level,  as provided




for by Alternative 2.  Review of the control  technology  and cost




information indicates that in many circumstances it is not unreas-




onable to achieve a post-control indoor radon decay product level of




less than 0.005 WL above normal background (0.009  WL  gross).  However,




at indoor radon decay product levels less than 0.009  WL  (gross)  it




becomes increasingly difficult to accurately measure  and differentiate




the observed level from normal background.   Other  sources  of radon




other than those amenable to control by the  available technologies may




significantly contribute to the observed indoor  radon decay product




air concentrations.  These factors tend to increase the  implementation




problems for local agencies at and near the  0.005  WL  above background




level.









6.4  SELECTION OF RADIATION PROTECTION  LEVELS




     In developing radiation protection guidance,  the following




objectives are important in selecting appropriate  action levels:






                                   83

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     1.  Minimize the health risk to the affected population.




     2.  Determine that recommended radiation levels can be measured




with reasonable accuracy, and, when necessary, differentiated from




normal background.




     3.  Determine that suitable control measures exist to reduce




indoor radiation levels to the recommended levels.




     4.  Determine that application of control measures does not




require the expenditure of unreasonable resources by individuals,




government authoritities or other groups.




     5.  Determine that the recommendations can be understood and




practically implemented by State and local responsible authorities,




and by the general public.








These objectives call for a series of judgments on the part of  the




Agency in its guidance role, and the State or County in their role  as




implementing authorities.








6.4.1  Radon Decay Product Levels in Existing Structures




     As shown in Figure 8, some control of indoor radon decay product



levels in existing structures can be considered cost-effective  at all




initial levels greater than 0.01 to 0.02 WL (including background).




This assumes control costs of $900 - $2600 per structure and 80




percent reduction.  However, if the initial level is sufficiently




high, remedial action at these cost levels and at 80 percent reduction



efficiency may not be sufficient to bring a structure down to the

-------
0.01-0.02 WL range.  Therefore, the selection of an action level equal



to or above this lower bound is also dependent more on practical



considerations of the degree of reduction economically achievable.  As



illustrated in Table 13, the most basic factor bearing on economically



feasible implementation is the proportion of structures .which require



application of nonconventional control measures (i.e., other than



those listed in Table 12), in order to be brought into compliance with



the numerical criterion selected.  At successively lower action



levels, the fraction of structures not easily remediable increases.



At 0.01 WL, for example, 15 percent of structures located on phosphate



land are projected to require more than readily achievable reduction



in levels compared to none expected at .03 WL, as extrapolated from



the EPA/DHRS survey.  Using the .03 WL value as a baseline (i.e.,



assuming that no unusual costs are projected at this level), addi-



tional costs of $260,000 - $6MO,000, and $2,600,000 - $6,400,000 would



be accrued,respectively, at 0.02 WL .or 0.01 WL (assuming that 1/3 of



structures not conventionally remediable require special corrective



action at a cost of $10,000 - $25,000 per structure).  The cost-



effectiveness of applying these "special" measures is generally in



excess of hundreds of thousands of dollars per health effect averted.



This obvious disparity between the cost-effectiveness of conventional



measures compared to unconventional ones is a result of the latter*s



high cost coupled with the relatively small additional reduction



achievable.
                                   85

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                                                                   TABLE 13

                                                      IMPACT OF ALTERNATIVE CRITERIA FOR
                                                     INDOOR RADON DECAY PRODUCT EXPOSURE
                                              FOR STRUCTURES REQUIRING SPECIAL CORRECTIVE ACTION
(1)
(2)
Number and Percent
of Structures in Excess
Recommended
Remedial
Action Level
(RRAL)
.03 WL
.025 WL
.02 WL
.015 WL
.01 WL
(A)
EPA/DHRS
Survey
(N=104)
20
23
25
30
45
(B)

Extrapolated
(N=4000)
760
880
960
1160
1720
(0


Percent
19
22
24
29
43
(3)
Number and Percent of Structures
not Conventionally Remedial*
(A)
EPA/DHRS
Survey
(N=104)
-
1
2
7
20
(B) (C)

Extrapolated
(N=4000) Percent
-
40 1
80 2
270 7
770 19
(4)
Extrapolated Total Cost
of Special Corrective
Action for Structures
not Conventionally
Remedial**
(N=4000)
-
$130K - $320K
$260K - $640K
$900K - $2,200K
$2,600K - $6,400K
(5)
Cost-effectiveness
of Special
Corrective Actions
(dollars per health
effect averted)***
-
$140K - $430K
$170K - $560K
$220K - $81 OK
$330K - $1,500K
  •Assuming 80 percent efficiency of control measures  in  reducing  indoor radon decay product levels which exceed background.

 •"Assuming 1/3 of structures not conventionally remediable  require  special corrective action,  at a cost of $10,000-$25,000 per structure.

•••Assuming the above efficiency and costs for reduction  from this and  the previous RRAL for a  structure housing 3-5 people.

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     The development of appropriate action level, therefore, requires



judgment as to the most acceptable balancing of overall cost-



effectiveness with practical considerations, such as achievability  of



control levels and measurement error.  Given the aforementioned  cost



of applying unconventional remedial measures and the problems



associated with measurement error at the lower levels, it appears



unreasonable to recommend mandatory action at levels less than 0.02




WL.  Within the 0.02 to 0.03 range (the latter again representing a



level projected to be reasonably achievable in all structures),  the



acceptability of a projected less than one percent of existing



structures requiring non-cost-effective remedial action must be  based



on a judgment on the appropriate allocation of resources to achieve



reductions in health hazard, and the capability and willingness  of



responsible parties to provide assistance programs for those



structures requiring additional corrective action.








6.4.2 Radon Decay Product Levels in Planned Structures



     Reduction of indoor radon decay product levels is more practical



in new than in existing structures as shown in Figure 8.  This is



because structure design, site preparation, selection of construction



materials, and the location can be planned.  Through careful con-



sideration of these factors, almost all structures can and should be



designed to achieve ALARA, or 0.005 WL above background, as determined



for construction on phosphate land in Florida.  It is possible
                                   87

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that in some cases following construction using what was anticipated



to be properly designed control measures, the indoor radon decay



product level will be greater than 0.005 WL above normal.  In some of



these cases additional controls may be warranted but in others the



lowest practical level may already be achieved.  Such a determination



will require a case-by-case review.  The cost-effectiveness of these



additional controls would, of course, be the same as that for existing



structures as shown in Figure 8.








6.4.3  Gamma Exposure in Existing Structures



     The highest indoor gamma radiation dose observed in the exam-



ination of 1102 residential structures in Florida was 190 mrem/yr



(27 yrem/hr assuming 75 percent occupancy).  It is not expected  that a



significant number of structures with indoor radiation levels much



above or equal to this value will be identified.  As shown in Figures



11d and e, the apparent cost of reducing this exposure is high and it



appears unreasonable to attempt reduction of such gamma levels in



existing structures.








6.4.4. Gamma Exposure in New Structures



     As is the case for radon, the availability and cost-effectiveness




of control measures for gamma radiation exposure  (as shown in Figures



lla-lle and discussed in the preceding section) in residences is such



that in most situations anticipated  in Florida on phosphate  lands, it
                                    88

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is reasonable to design and site a new residence so that the  indoor




gamma radiation exposure rate in the completed structure is less  than




5 yR/h above normal gamma radiation background (normal  is approxi-




mately 6 yR/hr).  Assuming 75 percent occupancy, exposure at  this




rate(11 yR/h) is estimated to result in about 100 additional  cancer




fatalities annually per 100,000 persons exposed over a  lifetime.




Designing structures to achieve an indoor gamma exposure rate less




than about 10 yR/hr (gross) is impractical, since differentiating




between normal background and elevated levels becomes increasingly




difficult below 10 yR/hr.  Also, as in the case for radon daughters,




other sources of radioactivity such as construction materials, may be




significant contributors to the overall gamma exposure  at these




levels.  Because of high retrofitting cost, once a structure  is built




using a design and siting plan to minimize indoor gamma radiation




exposure, no additional control is warranted for gamma  reduction even




if the recommended gamma ray exposure guide is exceeded.
                                   89

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                              SECTION 7.0




                         SOCIO-ECONOMIC IMPACT








7.1  GENERAL CONSIDERATIONS



     At present, the socio-economic impact of implementing remedial




measures can only be evaluated on a qualitative basis, with emphasis




on the identification of probable areas of impact.  The actual number




of residences affected, the field effectiveness of control measures




and their specific costs, as well as the availability of financial




aid, are among the factors not totally known at this time. Additional



information in each of these areas may have a substantial effect  on




socio-economic impact.



     The region under consideration includes about 300,000 acres  of




land in central and northern Florida.  Three general areas are covered




by the following discussion:   impact on  public and private




institutions and services, impact on business and employment  patterns,



and personal impact.








7.1.1  Impact on Public  and Private Institutions  and  Services



       Evaluation  of  potential impacts in  this area  includes




modifications in the  availability of housing  in  the  region  as a  result




of radiation protection  measures, and  the  added  burden  on  local  health




and building inspection  departments.   Among  the  primary forces that




would  affect availability and  property values negatively are  the
                                    90

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reluctance of developers and private builders to use phosphate land,




and possibly, the higher selling price (to cover the additional cost)




and/or poor market for houses that have had remedial action.  The




magnitude of these factors depends upon the availability of




alternative construction sites, the ingenuity of construction firms in




incorporating remedial measures into housing plans, and the attitude




of potential home purchasers toward houses with remedial measures.




These factors would, in turn, rely on the type of remedial measure




implemented, its cost, and the degree of assurance for the builder or




homeowner that radiation levels will be effectively reduced.




     The effect of the additional workload on local government from




implementing necessary radiation protection measures could be




significant, at least initially.  There will be a need for additional




inspections, surveying and recordkeeping, as well as laboratory




facilities for radiological analyses.  The availibility of the




necessary additional resources will be dependent on the financial




resources of the individual local health and housing departments.  In




some cases either local programs may require cutbacks or the




recommendations may not be implemented fully.  To estimate the total




potential economic impact on industry and the housing market




quantitatively would be totally speculative at this time.  At a cost




of about $50-100 to determine radiation levels in one structure, the




evaluation of the 4000 structures estimated to be in the region would




cost about $200,000-$400,000.  Clearly, these values could vary




depending upon the present capabilities of the local agencies.
                                   91

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7.1.2  Impact on Business and Employment Patterns




       With respect to the local economy, an equilibrium will result




between the positive and negative aspects of implementing a remedial




action program.  The positive aspect would primarily be the economic




advantages to business dealing with products or services called  for in



the remedial action program.  The negative aspect would be the




detrimental effort such implementation could have on businesses




dealing with housing construction or land development.  The net  effect




for the area in question would be dependent upon a number of




variables, the most important of which is likely to be the impact  of




reduced home construction and/or sales, whatever the reason (e.g.,




public attitude).  For a high growth area such as Central Florida  this




would be of some consequence if realized, although the low cost  of




control measures for new residences should make a significant impact




on construction  firms from this cause a remote possibility.








7.1.3  Personal  Impacts




       Some degree of personal impact is  likely for those persons



residing in structures which have been found to be in need of remedial




action.  Depending upon the type of measure implemented, some degree




of disruption  to the occupants' lives, either through the initial




incorporation  of a passive  remedial measure, or the periodic




maintenance required for one of a non-passive nature, may result.   The




cost  of the remedial action, if necessary, may  also have  to be  assumed




fully or in part by the homeowner, thereby, posing a significant
                                    92

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economic burden.  However, this negative impact may  be merely  one




segment of the overall cost to the homeowner, since  the  presence of




any remedial measures (other than the truly passive  ones such  as crawl




spaces) may affect the saleability of the residence  and  its market




value.  Other determining factors would be the status of the housing




market in the area and attitudes of buyers towards the radiation




problem and remedial action.








7.2  MAGNITUDE OF THE AREA POTENTIALLY AFFECTED




     About 120,000 acres of land have been mined  for phosphate  rock  in




Florida; of that amount, about 50,000 acres have  been reclaimed to




various degrees.  Estimates suggest that approximately 7>500 acres are




being used for residential housing or commercial  purposes, with about




1,500—4,000 structures.  The total acreage which  contains elevated




radium-226 concentrations near the surface, but is unmined, is  unknown




at present, but preliminary research indicates that  it may be  quite




significant.




     Land underlain by phosphate ore is located in the Central  Florida




counties of Hillsborough, Polk, Manatee, Hardee,  Highlands, Desota,



and Sarasota as well as several Northern Florida  counties.  Based upon



field experience, we do not believe that all of the  land where




phosphate ore is located or all of the disturbed  phosphate mine lands




will pose indoor radiation exposure problems to residents of




structures built there.  Nonetheless, because of  the radium-226




content of phosphate materials, the potential for indoor radon
                                   93

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daughter problems must be anticipated and adequately evaluated




wherever the phosphate materials and associated radium-226 are




present.  It is important to note that radium-226 associated with




other minerals in Florida, such as rare earths, titanium, and monazite




sands, may pose similar risks to residents.









7.3  ECONOMIC IMPACT OF REMEDIAL ACTION




     Characterization of the economic impact of implementing remedial




measures for both existing and planned structures is performed  by




consideration of the cost range of probable implementation scenarios.




Consideration is specifically limited to remedial costs as listed  in




Table 12, although it is recognized that impacts as described in the




preceding section would also be applicable.  As estimated in the DHRS




Final Report (1978), there are approximately 4000 structures built on




phosphate reclaimed land in Polk and Hillsborough Counties.




Statistics are not readily available on the number of new structures




being built or considered for reclaimed phosphate land.  However,  a




rough estimate can be made on the basis of annual housing starts for




those cities and towns located in the vicinity of identified areas of




reclamation.  From data published by the Bureau of the Census (1977),




approximately 400 housing starts are noted for incorporated munici-




palities located in such areas of Polk and Hillsborough Counties for




1976.  There were 3012 housing starts in unincorporated areas of both




counties in 1976.  Approximately 50 in Hillsborough County and  950 in




Polk County are assumed to be located in the phosphate area as
                                   94

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defined-in information derived from the respective county building




permit offices.  Of the 1400 total housing starts, as many as 40




percent may need control measures to meet the recommended design




objectives, based on an analysis of the distribution of existing




structures.  Therefore about 500 structures, or about 15 percent of




new residential construction starts in the two counties, are projected




to require remedial consideration per year.




     From the combined (EPA and DHRS) TLD air sampling data collected




and the application of the findings made in Section 6, the remedial




cost range for the 4000 existing structures can be projected.




With .02 (including background) WL as an upper control level,




approximately 24 percent of the total sample, or 960 structures out of




the estimated 4000 structures, is projected to be in excess.  In




addition, one third of 2 percent of structures may require special




corrective action to meet this control level at a cost of $270,000 -




$670,000.  At a lower control level of 0.009 WL (0.005 WL + 0.004 WL




background), approximately 40 percent of existing structures or a




total of 1600 structures on reclaimed land would exceed this




criterion.  Assuming an average remedial cost per structure of



approximately $1,000, as derived from Table 12 (assuming application



of polymeric sealants), a cost of one to one and a half million




dollars is projected for this range of control levels.  Selection of




an appropriate measure and cost for existing structures is difficult




due to lack of data, but, generally, the individual cost of the




various available control measures is similar and this figure ($1000)
                                   95

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is representative of any of them.  With more limiting mandatory action



levels (e.g., 0.01 or 0.02 WL), the total cost projected would be



higher commensurate with the number of structures requiring additional



or special corrective action to satisfy the recommended control



level.  With a mandatory control level of 0.01 WL, and assuming that



all not conventionally remediable structures identified in Table 13.



require special corrective action, rather than only one third, and,



further, assuming a cost for such special corrective action of $25,000



per structure, the maximum total cost would be $17,000,000.



     Estimates for future structures to be built on reclaimed land



assume 500 construction starts per year over a ten year period, with



the cost of control over this period of time being $500 per structure



for a total of about $2,500,000.  The economic impact due to remedial



action in both counties for such a ten year period would be about



three to four million dollars (undiscounted 1977 dollars).  This



estimate is clearly a function of the rate of new house construction



on reclaimed land, which in turn depends on many variables, including



the growth rate of the counties, availability of reclaimed land,



zoning requirements, etc.  Due to the relatively low cost associated



with crawl space implementation, however, this cost estimate is



probably a low one, assuming that other types of structure would also



be built.
                                    96

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                              SECTION 8.0




            IMPLEMENTATION OF RADIATION PROTECTION MEASURES








8.1  FEDERAL ROLE




     These findings were developed through the Agency's authority  to




provide technical assistance to States.  The U.S. Environmental




Protection Agency has no authority to directly enforce recommendations




in the State of Florida.  However, under authority transferred to  the




Agency in 1970, EPA can develop Federal guidance  for protection  of




people exposed to radiation sources associated with structures.  Such




guidance would apply to Federal agencies in the conduct of their




regulatory and other programs.








8.2  STATE AND LOCAL ROLE




     In order to implement radiation protection measures  effectively,




it will be necessary for State and local agencies within  Florida to




enforce and carry them out.  To this end, appropriate State and  local



agencies could adopt measures such as those discussed in  this document



through their own regulations which could be in the form  of zoning




requirements, building codes, standards, or some  other suitable




mechanism.  In some cases, in order to provide effective




implementation, additional State and/or local authority may be



necessary.
                                   97

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8.3  CONDUCT OF STRUCTURE EVALUATIONS




     In carrying out remedial action, State and local governments, as




well as private individuals or groups, will need  to conduct a variety




of measurements and evaluations to make appropriate decision-making




possible.  To assist uniform application of any recommendations,  the




Agency has developed suggested measurement guides for assessing




radiation levels in existing structures.  Information on  indoor  radon




decay product exposure is necessary  to determine  whether  remedial




action is warranted.  In planning new structures,  data  on gamma




radiation exposure is necessary.  All radiation measurements  should be




performed by trained technicians using properly calibrated radiation




detection equipment.




     Indoor radon decay product air  concentration measurements  should




be made using a Radon Progeny Integrating Sampling Unit (RPISU)  or




some other appropriate system.  If the RPISU  or similar device  is




used, the average indoor radon decay product  level for  a  test



structure should be  the mean of four to  six measurements  made over a




one-year period.  Single measurements  totalling less  than 2^  hours



integrating time or  multiple measurements of  less than  125 hours




should not be used in  determining  the average indoor  radon decay




product  level unless absolutely necessary.  Devices such as




instantaneous working  level meters,  grab radon or radon daughter




product  samples, and track-etch  films may  be  helpful  in screening




numerous  structures  to  determine  those most  likely to exhibit elevated
                                    98

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indoor radon daughter levels.  However, they should generally not be




used for remedial action decision-making unless the data is  shown to




be of quality comparable to that obtained with the RPISU device.  We




anticipate that work by the Agency or other groups may be able  to




improve the decision-making usefulness of short-term measurements in




the future.








8.4  CONTROL COST-EFFECTIVENESS ASSESSMENT




     Current Federal guidance for radiation protection provides for




reduction of exposures to as low as reasonably achievable (ALARA).  It




is recognized that such guidance requires decisions at the local level




regarding which exposure level can be considered ALARA.  This value




will differ from case to case and there are several factors  to  be




considered.  First, the reliability of the data should be appraised.




How much measurement error is involved?  Second, the normal  background




level, which is conventionally the initial baseline for ALARA,  should




be considered.  Third, the cost to achieve the desired exposure




reduction should be evaluated.  This factor is extremely important.




If the cost is minimal, then nearly any reduction (to normal




background) would be desirable.  However, if the cost is substantial,




then the associated potential decrease in risk must be weighed  by the




homeowner or the local authorities to determine if the application of




control technology is warranted.  Fourth, the potential impact  of the




dwelling on future inhabitants must be considered.  If the structure
                                   99

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is very old and in poor condition and is unlikely  to be  inhabited  to



any significant degree in the future, it will have less  long-term



impact on public health. Fifth, the social inconvenience  and  other



impacts on the inhabitants may be considered.  The installation  of



control technology may cause a significant disruption  to  the  normal



lifestyle and adverse impact on the well-being of  the  inhabitants.



Sixth, the economic situation of the inhabitants should  be  evaluated.



Some residents may be unable to afford  to install  control technology



due to adverse economic circumstances.



     These factors are not listed in order of importance  since  they



clearly vary from situation to situation, nor do they  represent  all



factors that may need to be considered.  However,  it must be



emphasized that the decision on whether remedial action  is  warranted



at any level should be based upon an overall evaluation  of  what  is



cost-effective and practicable for present and future  occupants.
                                   100

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         Biological Effects of Ionizing Radiation, Division of Medical
         Sciences, National Academy of Sciences, PB-239 735/AS,
         National Technical Information Service, Springfield, VA
         22151.

Na 75    National Council on Radiation Protection and Measurements
         Natural Background Radiation in  the  United States, NCRP
         Report No. 45, Washington, D.C., November  1975.

Na 76    Health Effects of Alpha-Emitting Particles in the Respiratory
         Tract.  Report of the Ad Hoc Committee on  "Hot Particles" of
         the Advisory Committee on the Biological Effects of Ionizing
         Radiation, Division of Medical Sciences, National Academy of
         Sciences, EPA  520/4-76-013, National Technical Information
         Service, Springfield, VA  22151.

Oa 72    Oakley, D.T.,  Natural Radiation  Exposure In The United
         States, ORP/SID72-1,  U.S. Environmental Protection Agency,
         Washington, D.C., June 1972.
                                   104

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Pe 70    Peterson,  Paux,  Letter of R.L. Cleer of the Colorado State
         Health Department transmitting the Recommendation of Action
         for Radiation Exposure Levels in Dwellings Constructed on or
         with Uranium Mill Tailings, U.S. Public Health Service,
         Washington, D.C., July 1970.

Ra 76    Radford,  E.P.,  Report to the National Institute of
         Occupational Health on the Status of Research on Lung Cancer
         in Underground Miners in Europe, 1976.  Order #96,3825,
         NIOSH, Cincinnati, OH.

Ro 78    Roessler,  C.E.,  Wethington, J.A., and Bolch, W.E.
         Radioactivity of Lands and Associated Structures, Fourth
         Semiannual Technical Report, University of Florida,
         Gainesville, February 1978.

Se 73    Sevc, V.  and Placek, V., Lung Cancer Risk in Relation to Long-
         Term Exposure to Radon Daughters in Proceedings of the Second
         European Congress of Radiation Protection.  Ed. by E. Bujdoso
         Akademia Kiado', Budapest (1973).

Se 76    Sevc, J.,  Kunz,  E. and Placek, V., Lung Cancer in Uranium
         Miners and Long-Term Exposure to Radon Daughter Products.
         Health Physics,  30:433, (1976).

Sn 71    Snihs, J.O., The Approach to Radon Problems in Non-Uranium
         Mines in Sweden, pp. 900-911 in Proceedings of the Third
         International Congress of the International Radiation
         Protection ^ssociation.  Edited by W.S.
         Snyder.CONF-730907-PZ, National Technical Information
         Service,  Springfield, VA  22151 (1974).

St 76    Sterling,  T.D.  and Weinkam, J.H., Smoking Characteristics by
         Type of Employment.  J. popup. Med., If}: 743 (1976).

St 77    Stowasser, W.F.  Phosphate Rock, 1975 Mineral Yearbook, Bureau
         of Mines,  Department of Interior, 1977.

Tr 75    Train, R.E., Letter to Governor Reuben Askew, U.S.
         Environmental Protection Agency, Washington, D.C., September
         22,1975.

Un 75    Lifetables, United States, 1969-1971, Vol. 1, No. 1, DHEW
         Publication (HRA) 75-1150, National Center for Health
         Statistics, DHEW, May 1975.

Un 76    United States Environmental Protection Agency, Environmental
         Radiation Protection Requirements for Normal Operations of
         Activities in the Uranium Fuel Cycle, Final Environmental
         Statement, Volume 1, EPA 520/4-76-016, Washington, November
         1976.

                                  105

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Un 77    Sources and Effects of Ionizing Radiation, UNSCEAR 1977-

Wa 71*    Wang, K.L. Economic Significance of the Florida Phosphate
         Industry Information Circular 8653, Bureau of Mines,
         Department of Interior, 1974.

Wa 77    Walsh, P.J., Dose to the Tracheobronchial Tree Due to
         Inhalation of Radon Daughters, pp. 192-203 in Tenth Midyear
         Topical Symposium of the Health Physics Society.  Rensselaer
         Polytechnic Institute, Troy, N'.Y. 12181, 1977.

Wi 78    Windham, S.T., Savage, E.D., and Phillips, C.R., The Effect
         of Home Ventilation on Indoor Radon and Radon Daughter
         Levels, EPA 520/5-77-011, U.S. Environmental Protection
         Agency, Montgomery, AL, 1978.
                                   106

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                                 GLOSSARY

Activity  - The number of nuclear transformations occurring in a given
quantity of material per unit time.  The curie is the special unit of
activity.  One curie equals 3-7 x 10^ nuclear transformations per
second (abbreviated Ci).

Apatite -Any of a group of calcium phosphate minerals of the approximate
general formula Ca (F, Cl OH,1/2 CO) (PO) occurring variously as
hexagonal crystals and granular masses; or in fine-grained masses as the
chief constituent of phosphate rock and of bones and teeth, specifically
calcium phosphate fluoride CaF(PO).

Benef1ciation- The processing of ores for the purpose of (1) regulating
the size of a desired product, (2) removing unwanted constituents,
(3)iroproving the quality, purity or assay grade of a desired product.

Decay product-  A nuclide resulting from the radioactive disintegration
of a radionuclide, formed either directly or as the result of successive
transformations in a radioactive series.  A decay product may be
radioactive or stable (also known as a daughter).

Gamma Radiation-  Short wavelength electromagnetic radiation of nuclear
origin (range of energy from 10 KeV to 9 MeV) emitted from the nucleus.

Latent Period - The period or state of seeming inactivity between the
time of exposure of tissue to an injurious agent and response.

Matrix - The subsurface of material containing a mineral or metallic ore.

Pressurized ion chamber - A pressurized gas-filled chamber used for the
detection of ionizing radiation.  The increased pressure enhances its
ability to monitor low-level gamma radiation (1-200  R/hr).

Radon - A heavy radioactive (alpha and gamma) gaseous element of the
group of inert gases formed by disintegration of radium.

Radiogenic - Produced by radioactivity.

Relaxation length - An absorber thickness which reduces the intensity of
the radiation by a factor of 1/e.

Scintillation instrument - A device for detecting and registering
individual scintillations (flashes) of light produced in a phosphor by an
ionizing event as in radioactive emissions.
                                    107

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TLD air pump - A device used to measure radon daughter  levels  utilizing
techniques of thermoluminscent dosimetry.

Track-etch film - A device used to measure radon daughter  levels
utilizing a 1/2" x 1" plastic chip which  is coated with cellulose
nitrate.  The alpha particles (produced by radon daughters)  react with
the cellulose nitrate, thus leaving a record.

 uR/hr - Microroentgen per hour (1 x  10 roentgen per  hour).  Unit used
for gamma radiation levels.

WL (Working Level) - The potential alpha  energy from  short-lived
daughters of radon which will produce 1.3 x  10-> MeV in  one liter  of air.
                                    108

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                                APPENDIX A




                 STUDY DESIGN - TECHNIQUES AND PROCEDURES




I.   PILOT STUDY DESIGN




     In June 1975, a limited field study was initiated to determine




whether the elevated concentration of radium-226 in reclaimed phosphate




land has an impact on increasing the radon decay product levels in




structures built on the land.  A sample was selected of Polk County




structures built on reclaimed and non-reclaimed land.  Except for that




variable (i.e., reclaimed versus nonreclaimed), structures were selected




as randomly as practicable.  The overall sample size was 125 structures,




with two-thirds of them being reclaimed land sites.  The remainder were




nonreclaimed land sites, some in the phosphate district.  This limited




study was not intended to evaluate radon decay product levels in all




structures throughout the County, but rather to give a perspective on the




possible problems and thereby point the way to further evaluation, if




needed.








II.  GAMMA EXPOSURE INSTRUMENTATION




     Gamma radiation levels inside and outside structures were determined




with Ludlum Model 125 Micro R meters that were calibrated with a



Reuter-Stokes Pressurized Ion Chamber relative to a slab source




(phosphate materials).  These instruments are shown in Figure A.1.

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Figure A.I - Gamma Radiation Measurements
(L to R: Reuter-Stokes Pressurized Ion Chamber
and Ludlum Model 125 Micro R Meter)

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III. RADON AND DECAY PRODUCT MEASUREMENT TECHNIQUES



     Two techniques were employed for measuring the radon decay product



levels within structures, TLD air samplers and track-etch badges.






     a)  Radon Progeny Integrating Sampling Unit (RPISU)



     The primary air sampling system used by the Environmental



Protection Agency, Office of Radiation Programs (EPA/ORP) was



developed by Colorado State University, Fort Collins, Colorado.   It  is



known as the Radon Progeny Integrating Sampling Unit  (RPISU) and



utilizes the detection techniques of thermoluminescent dosimetry



(TLD).  This device is shown in Figure A.2.



     The air pump is located inside two pieces of polyvinyl chloride



(PVC) pipe.  The PVC pipes are of different diameters and the area



behind the pipes is filled with sound deadening material.  The pump  is



attached to a sampling head which is located outside  of the pump



housing.  This sampling head, which is actually a hypodermic syringe



filter holder, contains the TLD's.  The filter head is made up at the



EPA facility in Las Vegas, Nevada, or Montgomery, Alabama, and



packaged in a small 3" x 5" envelope.  This envelope  also provides



space for the entry of the necessary field data.



     During operation, air is pulled through the sampling head and the



particulate material containing the radon decay products is trapped  on



a one-half inch filter.  A TLD (CaF:Dy) is located in the airstream



directly before the filter and the alpha energy from  the decay of the
                                  A-3

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Figure A.2  - Radon Progeny  Integrating
_   -, •	  TT_-:J- /'D'DTRTn
             A-4

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radon daughters is recorded by this" TLD.  A second  TLD,  separated from


the first by a stainless steel washer,  is also  located  in  the filter

head.  The first TLD is referred to as  the alpha TLD  and the second as

the gamma TLD.


     The filter head is placed on the sampler,  and  the  starting sampler


information consisting of the reading on a running  time  meter,  a location

number, date and time, and air flow (measured by a  calibrated rotometer)


is filled in on the envelope.  The sampler is usually left in place for

one week.  Information on date, time, and flow  rate at  cut-off is entered


on the envelope.  The envelope with the filter  head is  then returned to


the Las Vegas facility.  The head is taken apart, the TLD's read out on a


Harshaw TLD reader, a data form completed and sent  for  computer analysis,

                                                                  *
and the finished printout containing the calculated working level  (WL)


retrieved.


     The working level is calculated by providing a working level-

liter/nanocoulomb (WL-l/nC) conversion  factor for the TLD  reader, nC

readout for gamma and alpha TLD, the running time of  the sample, the on


and off air flow rates and the'number of the rotometer  used.

     The net nC value is obtained by subtracting the  gamma TLD nC

(background gamma radiation) from the alpha TLD nC  (alpha  decay energy

plus background).  This value, multiplied by the conversion factor and

divided by the correct air balance, produces the WL value  average for the

period of exposure.
     WL - The working level is defined  as  the  potential alpha energy
from the short-lived daughters of  radon which  will  produce 1.3x!05MEV
in one liter of air.


                                   A-5

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     b) Track-etch Films


     The track-etch badge consists of a one-half inch by one inch


plastic chip which is coated with cellulose nitrate.  As radon  and  its


decay products are formed, alpha particles are produced.  When  the


alpha particles strike the cellulose nitrate, a record of their


passage is made.  The badges were each numbered, and two of the badges


were usually mounted on a cardboard card which can be positioned on a


wall. The badges were left in place from six months to a year and


collected, then dipped in a caustic solution (NaOH) or "etched".  The


alpha particle's passage becomes an etched track, visible with  the  use


of a microscope.


     Each badge, after etching, was read by a technician using  a light


microscope with a calibrated field.  The number of tracks observed  was

                                                   p
recorded and the tracks per square millimeter (T/mm ) were


calculated. This value was then compared to a calibration curve and


the working level hours (WL-h) associated with the number of tracks


observed was obtained.  The WL short-lived daughters of radon which


will produce 1.3x10  MeV in one liter of air was then calculated,


using the number of hours the badge was in the sampling location.


     The badge has the advantage of being a passive dosimeter.   That


is, it is put in place and picked up, but no maintenance is required


during the sampling period (no moving parts).  However, it has  the


disadvantage of measuring or recording not only the alpha energy given


off by radon, but also by polonium-218 (radium A) and polonium-214
                                   A-6

-------
(radium C).  Since the alpha energy from radon is not a portion  of  the




alpha energy used to determine the WL (the radon daughters  and not  the




radon-222 itself are the prime contributors to adverse health impact),




the system must be calibrated so that the complement from radon  can be




subtracted.  This calibration will be discussed in  depth in a later




section.








IV.  INFORMATION COLLECTION AND ORGANIZATION




     In the initial survey of structures built on reclaimed phosphate




land, track-etch films were placed in 85 structures built on reclaimed




land and in 40 structures built on nonreclaimed land.  Structures




surveyed consisted primarily of private dwellings;  however, local




health department buildings and a few office buildings were also




surveyed.




     At each structure, data were obtained regarding its




classification (residence, business, etc.), construction type




(basement, slab, crawlspace, etc.), number of levels, material




(masonry, non-masonry), and whether it was air conditioned. A map  was



made of each structure showing the indoor and outdoor external gamma




radiation levels.  This data was computer coded according to location




identification number and address.  Data were added to the  computer




file on the indoor radiation level in the structure for both the RPISU




system or track-etch films.  Printouts are accessible by keying  the




file in several different ways, depending upon the  specific variable




of interest.
                                  A-7

-------
     After noting elevated levels in some structures in September



1975, the track-etch data base was expanded in November 1975.  Since



that time the State of Florida has selected 997 structures for study



either by TLD air pump, track etch film or both.  Further, as time has



become available for using the air pumps in additional structures,



they have been added to the TLD air pump data base.  The information



from the  study collected as of January 20, 1978, for TLD air pump




data are listed in the Annex.
                                   A-8

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                                APPENDIX B




                     CALIBRATION OF TRACK-ETCH FILMS




I.   DEPLOYMENT OF DOSIMETERS




     The calibration of the track-etch  films used  in  the  study  was




accomplished by randomly selecting 23 structures and  installing track-




etch films and air sampler (RPISU) devices  in each of them.   A  total of




two or three films were used in each structure.  In the  structures one




film was deployed for a period of about one year and  the  other  two films




were deployed for consecutive six month intervals  coincident with the



film which was in place for a year.  The RPISU devices were  operated for




approximately a one week period for four to seven  weeks  during  the year,




with at least one week in each of the four  seasons.








II.  STATISTICAL ANALYSIS OF THE DATA




     The data set for statistical analysis  included 41 points (N) from 23




locations, using two types of film measurements.   The first  was the set




of values of track density (T) for films exposed  for  the entire year,




while the second was constructed by summing results of two films exposed




in consecutive six month periods at the same  location.  These two types



of measurements did not differ significantly.  Corresponding air sampler




measurements (RPISU) for indoor working levels  (W) are averages of from




four to seven measurements taken during the study  period at  each of the




23 locations. The data was analyzed with  the  air  sampler data as the




independent variable and the  track-etch film  data  as  the dependent




variable.  The data are listed in Table B.1.

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Table B.1.  Data for Indoor Radon Study
            Track-etch density  (tracks
  Location    1st      2nd      1st+2nd
            six mos. six mos.
                                            Air Sampler
                                    entire year          (WLh)
   70050
   70051
   70076
   70079
   70082
   70084
   70087
   7009^
   70101
   70103
   70105
   70107
   70110
   70118
   70134
   70135
   70136
   70137
   70169
   70170
   70172
   70175
   70180
 7.6
 5.6
26.8
32.2
 1.3
 1.0
 5.3
 6.5
10.9

28.9
 3.5
 1.32
 1.16
  .98
  .95
   11
15.37
 1.82
 2.81
1,
5.
7,
         6.45
         2.48
        29.09
        19.00
        15.70
         3.64
         5.29
         4.30
         6.11

        22.64
          .65
          ,48
8.43
1.16
8.10
8.76
6.11
3.80
4.30
2.48
          14.05
           8.08
          55.89
          51.20
          17.00
           4.64
          10.59
          10.80
          17.01
51
 5
 3
 9
 1
 54
.15
,80
,59
,66
10.08
14.71
13.22
19.17
 6.12
 5.29
                    16.20
                     5.62
                    49.91
                    34.54
                    16.69
                      .83
                     4
                    31
                     3
                    ,63
                     07
                     80
10.08
 7.77
52.88
61.97
 1.32
  .45
  .31
  ,82
 8.92
 9.42
5.
2.
1,
                                         4.46
                                         4.30
 77
163
605
596
182
173
340
304
153
306
373
661
698
107
 19
 10
 10
 10
238
 69
314
 19
 28
     In order to arrive at an equation which  best  fits  the relationship

between track density on  the films  and air  pump measurements,  the

following regression analyses were  performed  on the data given in Table

B.1:

Option 1

         T = 0.4 +  .069 W

           (t=0.2)   (t=11)

         R2 = 0.87

         F = 124

         N = 41
                                    B-2

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Option 2



         T = -19.5 + 7.57 InW



             (t= -2.7) (t=5.1)



         R2 = .63



         F = 26



         N = 1*1



Option 3


         InT = 1.4 + .0037W



               (t=7)  (t=7.3)


         R2 = 0.76



         F = 53


         N = 41



Option 4



         InT = .09 + .46 InW



               (t=.2)  (t=5.0)



         R2 = .62



         F = 25


         N = 41
     These options cover the obvious linear and nonlinear  cases  that



could be considered.  (The t statistic is used to test the  statistical


                                               2
significance of its corresponding parameter.  R  is the proportion  of



the total variation in the dependent variable explained by  the regression



equation.  The F statistic tests the presence of a relationship  between



the dependent and independent variables of the regression equation.)
                                   B-3

-------
           2
Using the R  and F statistics as decision criteria  for  choosing the


best overall fit and prediction ability, Option  1 appears  to  be the


best.  That is, the simple linear form of the relationship between


track-etch and air pump data appears  to  fit and  predict better than


either the log-linear or log-log forms.  It can  be  seen that  Option  2 is


consistent with the null hypothesis that the intercept  is  equal to zero,


based on the t value.  This result appears to confirm  the  theory put


forth by D.B. Lovett that, "the track density resulting from  the exposure


of films to alpha particle activity is directly  proportional  to the  time


integral of the total alpha particle  activity of the atmosphere to which


it was exposed" (Lo 75).  Therefore,  a final regression was run in which


the intercept is omitted:


Option 5


         T = .070 W
         R2  =  .75
         F  =  12


         N  =  41
     This  is  taken  to  represent  the "best" fit between the track density


 on  the  film and  the TLD air  pump measurements.  The 95 percent confidence


 interval  for  a predicted W from  a measured T, based on option 5 is:
                  T                          T2
                	    + 250     .99 +  	
                ,069    ~~                  20,000
                                   B-H

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This formula is an algebraic manipulation of  the  confidence  interval




given in Equation 10.5 of Brownlee, 1965 (Br  65).  It should  be  noted



that the formula for the confidence interval  is -not  in  standard  form,




but has been rearranged for easier computing.




     The formulas given here are valid for exposure  times  of




approximately one year.  Results from analyses of six month exposures




suggest some seasonal variation and therefore conversions  from track




density to radon exposure based on short term data should  not be done




using these formulas.  Figure B.1 is a plot of the equation given in




option 5 with the 95 percent intervals identified.   As  the origin is




approached, the percentage of error rapidly increases.  For example,




at 60 tr/mm ,  the 95 percent interval is about —30 percent whereas




at 20 tr/mm  it is about —100 percent.








Reference:








Br 65    Brownlee, K.A. Statistical Theory and Methodology in Science




         and Engineering, 2nd Edition.  John Wiley & Sons, Inc.:  New




         York (1965) p.362.
                                  B-5

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                                                           Figure B.I
        1400
w
t
C7V
         1200 -
                                                                                    • ANNUAL DATA POINT



                                                                                    X SU;v1 OF 2 CONSECUTIVE 6 MO DATA POINTS



                                                                                — — 95% CONFIDENCE LEVEL



                                                                                      W=T/ 06978
                                                        .1	1	L

                                                        40          50          60

                                                         TRACK DENSITY (TR/mm2)
100
                                            CALIBRATION FORMULA AT 95% CONFIDENCE LEVEL

-------
                               APPENDIX C




                  RADIATION EXPOSURE CONTROL MEASURES









I.   INTRODUCTION




     This assessment is extracted primarily from a survey of available




measures conducted and published by the Agency in November 1976  (Fi




76). It includes an update on control technology costs that have




changed since publication of the survey.  This evaluation focusses on




state-of-the-art radon decay product control measures for proposed




structures which have radon transport through the foundations.




Several of these measures have similar application for reduction of




radon decay product concentrations in existing structures as well as




reduction of external gamma exposure in both new and existing




structures.  Five available measures are assessed for




cost-effectiveness:  ventilation, polymeric sealants, ventilated crawl




space construction, excavation, and improved slab construction,  the




latter two having dual application for gamma and radon.  These




measures will be discussed in the context of existing and planned




structures.








II.  AVAILABLE TECHNOLOGIES




     a)  Utilization of Air Cleaners




         Air cleaners are designed to remove particulates from the




circulating air of building interiors.  The type of air cleaner  used




depends upon the particle size and shape, specific gravity,




concentration of the particulates, and the efficiency of removal

-------
desired.  Of these, the particle size, along with overall filtering



efficiency required, is the most important characteristic by which an




air cleaner is chosen.




         Electronic air cleaners use electrostatic precipitation




principles to collect particulate matter.  Unlike their industrial




counterparts, residential electronic air cleaners operate on standard




house current and with normal operation use electricity at the same




rate as a 50-watt lightbulb.  The performance of electronic air




cleaners depends upon the rate of air flow and the quality of




installation.  A number of commercially available models are designed




to meet these performance parameters, as well as others such as the




volume of air to be cleaned and the size of the heating or cooling




unit.



         As no data are available concerning the efficiency of air



cleaners in reducing the concentration of radon daughters, modeling




was performed to make such an estimation (Fi 76).  These calculations




show that theoretically, most of the  radon daughter  level reduction




occurs at effective ventilation rates of less than two air changes per




hour (approximately 70 percent).  Therefore, assuming that natural



infiltration accounts for one air change per hour, air cleaners,  which




can effectively handle ventilation  rates of about one to two air




changes per hour,  would have a  relatively marginal effect on working




level  reduction.   For HEPA  and  electronic air cleaners, a 38 percent




reduction in the equilibrium radon  daughter working  levels was




calculated.  For HEPA  filters,  though,  increased  effective ventilation
                                   C-2

-------
 rates could lead  to  an  increased  tracheobronchial dose (and therefore

 a potentially higher total  lung dose),  due  to  the resulting increase

 in the free ion fraction  of radon daughters (Ja 72).

         For a combined electronic air  cleaner and outside air

 exchange system,  an  efficiency of 62  percent was calculated for

 working level reduction.  This model  assumes a flow rate through the

 system of  1.5 air  changes per hour and  about 25 percent makeup air.

     b)  Polymeric Sealants

         Ideally,  if one  could completely seal all of the floor and

 wall space below ground level for a structure  with radon diffusing

 through the floor, the  problem would  be largely alleviated.   The radon

 gas that would normally diffuse through the floor would be trapped by

 this barrier so that it would decay in  the  structural material and not
                                  *
 enter the structure's atmosphere.   Polymeric  sealants,  having low

 permeability to radon gas,  have been  proven to be effective in

 reducing in-house radon progeny when  properly  applied.   An EPA funded

 study by Culot, et ajl., (Cu 73) showed  that radon diffusion into a

 structure could be reduced  by more than one half by utilizing an epoxy

 sealant.  An important  finding was that a significant reduction of

 radon diffusion into  structures could be obtained only  in a situation

 free of other major  pathways for  radon.  From  past analyses  with test
     There is a whole-body gamma exposure related  to  such  decay,
although in regard to potential health effects it  is  insignificant  in
comparison to radon daughter alpha exposure in the  lung.   From  past
field studies, fractional gamma increases of 2 to  20  percent were
measured for a 4-inch concrete slab after sealant  application.

                                  C-3

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structures on slabs, as well as experience with remedial action in


structures in Grand Junction, Colorado, it was determined that such


pathways do exist and are common in typical residential structures.


One such pathway is minute cracks in the concrete slab at the juncture


of the slab and wall, another is the channel through which pipes and


drains enter the slab. The analyses and field experience have shown


that without complete sealing of these pathways with a


radon-impermeable base, only a relatively small working level


reduction could be obtained.  The thoroughness of sealant application,


then, is of prime importance in the implementation of this control


measure.


     An efficiency range of 70-90 percent radon progeny reduction  for


polymeric sealants was derived from test data by Culot, et al.,  (Cu


73).  Their experiments involved the use of sealed tanks above a


sealed concrete slab with uranium tailings underneath.  Assuming an


equilibrium radon progeny concentration over the slab equal  to  10


percent of the source term under the slab, which they had previously


determined, the range of reduction was approximately 75-99 percent

                                                      *
using polyester styrene, polyester resin, and Omnitech  polymers.


From a similar experimental  analysis,  Auxier, £t al., (Au 74)  suggests


that an 88 percent  reduction in airborne radon  progeny  could be


obtained.  As these  reductions were achieved in an experimental  lab


situation, the reduction range of 70-90 percent was
     *0mnitech  Industries,  Inc.
                                   C-1

-------
chosen as a conservative approximation  of  actual  residential



application.'  Again, the degree  of  reduction  achievable would be



dependent upon the method and thoroughness of application.



     c)  Ventilated Crawl Space  Construction



         The function of building a crawl  space for  radon progeny



control is to provide a highly ventilated  space between the  soil



surface and the overlying structure in  which  the  emanating radon gas



can be diluted or removed before diffusion into the  structure.   The



degree to which such ventilation is effective is  dependent upon the



number of air changes per unit time within the enclosure below the



floor.  Assuming that a wooden floor would allow  radon  gas to diffuse



readily, the fractional reduction of radon gas diffusion into the



structure would be proportional  to  the  reduction  in  partial  pressure



of the radon in the crawl space due to  ventilation.   There are two



means by which the ventilation characteristics of a  crawl space can be



enhanced, involving passive and nonpassive measures.  First,  the crawl



space can be constructed utilizing  oversized,  properly  spaced vents on



all sides of the structure.  Second, a  fan could  be  set up for forced



ventilation of the crawl space, thereby establishing  a  lower  limit of



ventilation.  Although there is no readily  available  data concerning



the magnitude or range of the ventilation  rate which  could be



achieved, with proper construction  it could compare  favorably with a



well-ventilated house (2-*» air changes per  hour).  Assuming  such
                                  C-5

-------
ventilation rates, radon daughter working level reductions of 80

percent or more would be possible.  The level of reduction achievable

could be increased, if desired, through the use of a radon impervious

barrier in the floor. Such a barrier, possibly in the form of a

polymeric sealant underlying a seamless tile floor, would have side

advantages such as moisture proofing and a reduction in heating and

air-conditioning infiltration loss.

     d)  Site Excavation and Fill
                                                      *
     A ten-foot layer of soil with a relaxation length  of 4.9 feet

(for moist packed earth and dry packed uranium tailings with a
                             _2
diffusion coefficient of 5x10   cm/s) can be as much as 80 percent

effective at reducing radon emanation from the ground surface  (Sc

74).  Such data indicate that by removing this depth of reclaimed

phosphate soil and replacing it with non-uraniferous soil of the same

density and porosity, approximately 80 percent of the radon would be

retained in the ground. If such a procedure were done for a home site

on phosphate land, the diffusion rate of radon into the structures  to

be built would then be proportionally less, assuming negligible
                        **
lateral radon diffusion.
    *The depth  of a  uniform  layer  of  material  of the  same density in
which a diffusing gas  (radon in this  case)  is  reduced in  concentration
by a factor of  "e" (2.703).

    **Although  no field  studies have  been  performed concerning
lateral diffusion, the cost-effectiveness  calculations in Section V
allow for  excavation to  a  distance of three feet from the foundation.
                                   C-6

-------
     With regard to gamma exposure reduction, packed  earth  at




1.6 g/cm  density  has a tenth value  layer of 13  inches  (i.e.,  the




gamma radiation level is reduced by a  factor of ten over  this  thickness




at the assumed density).  Therefore,  an equivalent 80 percent  reduction




in exposure is achievable with only 9  inches of soil,  with  a 99+  percent




reduction for ten foot depth.  These  estimates assume no  contribution




from terrestrial sources external to  excavated soil.




     e)  Improved Slab Construction




     Another technique by which the overall effectiveness of radon




daughter control measures could be enhanced would be  improving the




quality of slab (quality control, reinforcement and thickness).   As  the




pore size present in the cement has a  large influence on  its radon




stopping ability, utilizing concrete with a low water to  cement ratio  by




weight (W/C) and dense aggregate material (such as granite  or  marble)




would decrease radon permeability.




     Increasing the thickness of the  concrete slab would  likewise reduce




the radon diffusion rate, assuming this is the major  pathway.  As radon




gas has a relaxation distance of about 5 cm (2 inches) in a standard




concrete (density =2.35 g/cm), by doubling the  thickness  of  a normal




4-inch slab to 8 inches, an 80 percent reduction  in exhalation  is




possible.  For controlling gamma irradiation through  the  foundations,




increasing the thickness of the concrete slab would lead
                                   C-7

-------
to a 70 percent gamma reduction.  This estimate is based on concrete




with 6 percent porosity, with an increase in slab thickness from  4  to




8 inches.  Unlike radon emanation, the presence of cracks would not




lessen the efficiency of reduction.








III. COST ANALYSIS FOR IDENTIFIED CONTROL TECHNOLOGIES




     A cost analysis on the utilization of radon daughter control




technology is critical to any decision-making process in this  area.




As with pollution control equipment in industry, the cost of control




measures would probably be passed on to the consumer, or the homeowner




in this case.  In order to minimize expenses, the builder must first




determine, from available data, which control measures  reduce  the




radon progeny concentrations down to acceptable residential levels,




and second, which of these measures can be implemented  and maintained




at the least cost to him.




     The cost figures utilized  in this analysis, as shown in Table




C-1, are best average estimates based on data derived from literature,




government, and private industry.  Because of their different  sources,




a small degree of variability is to be expected for the actual cost of




application in specific localities of the country.  Another source  of




variability is inherent in the  use of an average value.  Such  an




estimate is applicable only for an average site and, therefore, cannot




be generally applied.  All cost figures utilized in this analysis are




adjusted to present value (6 percent annual discount rate applied).
                                   C-8

-------
                                               TABLE C. 1
                    ESTIMATED AVERAGE COST OF CONTROL MEASURES FOR
                   STRUCTURES CONSTRUCTED ON FLORIDA PHOSPHATE  LAND*
n
CONTROL MEASURE
EXISTING STRUCTURES
AIR CLEANERS.
HEPA
ELECTRONIC
ELECTRONIC AND AIR EXCHANGER
POLYMERIC SEALANT
PLANNED STRUCTURES
VENTILATED CRAWL SPACE
EXCAVATION AND FILL
(TO 10' DEPTH)
COMMERCIAL FILL RATE -
FOR 80% RADON REDUCTION (INCLUDES 99%
GAMMA)
FOR 80% GAMMA REDUCTION
W/NOMINAL FILL COST -
FOR 80% RADON REDUCTION (INCLUDES 70%
GAMMA)
FOR 80% GAMMA RED
IMPROVED SLAB CONSTRUCTION:
FOR 80% RADON REDUCTION (INCLUDES 70%
GAMMA)
FOR 80% GAMMA REDUCTION
CAPITAL
COST

S400
S350
S900
S600S1950
S550


S3250S5500
S250S400

S2550-S2900
$200

S550
$600
ANNUAL
MAIN-
TENANCE
COST

$100
$25+ * * '
$25+
UNDEFINED
NONE


NONE
NONE

NONE
NONE

NONE
NONE
ANNUAL
ELECTRICAL
COST

UNDEFINED
$10
$80
NONE
UNDEFINED


NONE
NONE

NONE
NONE

NONE
NONE
TOTAL
AVG. ANNUAL
OPERATING
COST

$100
$35+
$105+
NONE
NONE


NONE
NONE

NONE
NONE

NONE
NONE
PRESENT
WORTH O(
TOTAL COST
(70 YRS)

$2050
$900
S2600
S600 $1950
S550


S3250S5500
$250 $400

32550 02900
$200

$550
$600
                                           1977 DOLLAR VALUE (6% DISCOUNT PER YEAR APPLIED), ALL FIGURES ARE FOR RADON
                                           NOTED
'ASSUMMING 1500 SQUARE FEET FLOOR AREA AND
 PROGENY REDUCTION EXCEPT WHERE OTHERWISE
*SEE TEXT
*"*-" SIGNIFIES THAT THE ESTIMATE GIVEN IS MOST LIKELY A MINIMAL ONE ALTHOUGH THE ACTUAL AVERAGE IS UNDEFINABLE USING
 AVAILABLE COST DATA

-------
     There are numerous components of the total cost, both tangible



and intangible, which will be considered.  The capital cost is the



most important component to the prospective builder, which would be



incurred in order to implement the control measure.  With mechanical



equipment such as air cleaners, maintenance and replacement costs also



become important in calculating the total cost.  As most equipment of



this type has a useful life of roughly ten years, some maintenance and



possibly replacement will be required over the average life span of a



building.  Another component is electrical cost which is, again,



primarily associated with the use of mechanical air cleaning



equipment.  Due to probable increased air infiltration in homes with



crawl spaces, there would be additional  electrical costs as a  result



of the corresponding increase in the use of air-conditioners or



electrical heating units.
                                   C-10

-------
                         APPENDIX C REFERENCES








Au 74    Auxier, J.A., Shinpaugh, W.H., Kerr, G.D., and D.J.




         Christian, "Preliminary Studies of the Effects of Sealants on




         Radon Emanation from Concrete," Health Physics 27:390-392,




         No. 4 (1974).








Cu 73    Culot, M.V.J., Olson, H.E., and K.J. Schiager, "Radon Progeny




         Control in Buildings," Colorado State University, EPA




         R01EC0015.3 and AEC AT (11-D-22733 (May  1973).








Fi 76    Fitzgerald, J.E., Guimond, R.J., and R.A. Shaw, A Preliminary



         Evaluation of the Control of Indoor Radon Daughter Levels in




         New Structures, EPA-520/4-76-018, U.S. Environmental




         Protection Agency, Washington, D.C., November 1976.








Ja 72    Jacobi, W., "Relations Between the Inhaled Potential -Energy




         of Ra-222 and Ra-220 Daughters and the Absorbed -Energy in




         the Bronchial and Pulmonary Region, Health Physics 23;3-11,




         No. 7 (1972).








So 74    Schiager, K.J., Analysis of Radiation Exposures on or Near




         Uranium Mill Tailing Piles, Radiation Data and Reports, U.S.




         Environmental Protection Agency, 15:411-425, No. 7 (1974).
                                  C-11

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                               APPENDIX D




                        EVALUATION OF FIELD DATA








I.   Evaluation of Radon Decay Product Level Data








D.1.1  General




     Data on indoor radon decay product levels were obtained  for  over



200 structures throughout Central Florida.  However, not all  of these




data are useful in describing the radiological situation.   In order  to




represent a year's exposure condition in a structure, it is desirable




to operate the air pumps (RPISUs) four to six times spaced  throughout




the year for approximately a week each time.  This proved to  be




difficult to achieve in many structures for several reasons.   First,




some residents refused to allow the devices to be operated  for those




time periods.  Second, smoking and other environmental  factors within




a structure sometimes clogged the filters and automatically stopped




the pumps after only a few hours of operation.  And third,  exchanges




of property sometimes precluded necessary followup measurements.




     During the study it was also learned that, in addition to not



being representative of long time periods of exposure,  short  air  pump




operational times (generally less than 24 hours) sometimes  were



predictive of indoor radon decay product levels considerably  higher




than extended runs in the same structure.  All of the reasons for this




observed phenomenon have not been discerned, although to minimize the




use of erroneous data, short run times were not utilized to determine

-------
structure averages.  In order to further improve the validity  of  the




measurements made, we have decided to report average indoor radon




decay product levels from structures with air pump operating times  of




more than 24 hours.  Also, the three or more measurements must total




more than 125 hours of combined operation to be included.




     Using the above data selection criteria, 133 structures were




identified from those in the original EPA pilot study  and the  group




chosen by DHRS.  TLD's from these air pumps were analyzed by the




Eastern Environmental Radiation Facility in Montgomery,  Alabama,  the




Radiation Office in Las Vegas, Nevada,  and Department  of Health and




Rehabilatative Services, Orlando, Florida.  All of  the data  from these




sources were combined, with each of these groups participating in




quality control checks and intercalibrations.   As a result  of  such




intercomparisons,  all the data  is believed  to be within +30  percent of




the  true value.   This is very  important to  consider when trying to



draw conclusions  about the need  for  remedial  action in a structure.




      Figure D.1 depicts  the breakdown of the  observed indoor radon



decay product  data according  to  percentage  distribution of the mean




gross indoor  level for  the entire  133 structures  in the composite




EPA-DHRS population.  This data is  summarized in Table D.1  by




percentile  in excess  of selected radon decay product levels for  the




EPA, DHRS,  and composite groups;  and for houses on reclaimed  or




mineralized land  only.
                                    D-2

-------
               35
               30
a

CO
               2b
en
LU
CC

I-
u

cc
t-
l/}
u.
o
               20
                                                                   N=133
               15
               10
                     .002WL  .004   006   008   .010    .012   .014   .016    018   020    022    024   .026

                                             MEAN GROSS WORKING LEVELS (FOR INTERVENING RANGES)
                                                                                         .032
                                                                                                034
                                                                                                     .036
                                                                                                            038
.040 WL > 040
                               Figure  D.I  PERCENT DISTRIBUTION CF TLD AIR SAMPLING MEASUREMENTS

-------
                                TABLE D.1
              Distribution of Mean Gross Indoor Radon Decay
      Product Levels (percent equal to or in excess of level noted)
      Level (WL)
      0.005
      0.01
      0.015
      0.02
      0.030
      0.040
      0.050
         EPA
       DHRS
     N=22  *N=15
      64$    93$
      55$    80$
      50$    73$
      41$    60$
      36$    53$
      23$    33$
      23$    33$
   N=111  «N=89
    65$     76$
    31$     37$
    17$     21$
    14$     18$
    11$     13$
      3$       3$
      2$       2$
       Composite

     N=133   »N=104
      65$      79$
      35$      43$
               29$
               24$
               19$
                8$
23$
19$
15$
 6$
 5$
                7$
     •Excludes houses on non-mineralized lands

D.1.1  Geographical Distribution

     The mean indoor radon decay product levels in the structures were

examined to determine if any trends could be noted in the geographical

distribution patterns.  These data are shown in Table D.2 and

represented on a general map of Polk County in Figure D.2.
     City
                   TABLE D.2
       Number of Structures in Specified
               WL Ranges by City

WL<0.01     0.01£ WL <0.03   0.03-WL<0.05  WLlO.05
                                           N
- 1
Auburndale
Bartow
Bradley Junction
Davenport
Dundee
Eagle Lake
Eaton Park
Fort Meade
Haines City
Lake Alfred
Lakeland
Lake Wales
Mulberry
Pierce
Polk City
Winter Haven
2 (100$)
2 (22.2$)
0
2 (100$)
2 (100$)
1 (100$)
2 (50$)
1 (33.3$)
9 (90$)
1 (100$)
42 (68$)
3 (100$)
16 (64$)
0
2 (100$)
5 (100$)
0
2 (22.2$)
0
0
0
0
1 (25$)
2 (66.7$)
1 (10$)
0
11 (18$)
0
5 (20$)
1 (100$)
0
0
0
2 (22.2$)
1 (100$)
0
0
0
1 (25$)
0
0
0
5 (8$)
0
4 (16$)
0
0
0
0
3 (33.3$)
0
0
0
0
0
0
0
0
4 (6$)
0
0
0
0
0
2
9
1
2
2
1
4
3
10
1
62
3
25
1
2
5
TOTAL
90
23
13
                   133
                                   D-4

-------
                                           LEGEND
               GROSS WORKING LEVELS  WL> 05—<-/"pV— WL< 01
                                03
-------
     Of 25 locations outside the general bounds of the phosphate




mineralized region in Polk County only one location had an average




indoor radon decay product level greater than  .01 WL.  The level  for




this structure was .011 WL.  This finding lends support to the




conclusion that normal soil unrelated to the phosphate region in  Polk




County generally exhibits low average indoor radon decay product




levels.  From the figure it can be seen that the highest levels are




generally observed in the southwestern region  of the county.  Clearly,




from the standpoint of focusing control on the areas of principal




impact at present this region is of primary concern.








D.1.3  Evaluation by Land Category



     The land on which the structures in the study are built was




classified according to four categories: non-mineralized (no phosphate




deposits), mineralized (deposits present, but  unmined), reclaimed,  and




"other" (due primarily to lack of information).  Of the 133




structures, the average gross indoor radon decay product level  for




each category is .003 WL for non-mineralized land  (N=29),  .015  WL for




mineralized land (N=9), .017 WL for reclaimed  land  (N=93), and  .009 WL




for land of unknown designation (N=2).  The data for  these categories




are given in Table D.3 and graphed in Figure D.3-
                                   D-6

-------
   100
   90
   80
    70
in

£  60
o
^—
o

cc


k  50
U-
O
H
Z
oJ
O
   30
   20
                                                                                                             N=2
WL< 01
03^WL< 05
            05
                                    WL< 01     03*£WL< 05           WL< 01      03 05           01
-------
                                   TABLE D.3

             Number of Structures  by  Land  Category  and Mean  Gross
                   Indoor  Radon Decay  Product  Level  Ranges

  Land Use         WL<0.01    0.011 WL< 0.03    0.031WL< 0.05    WL>. 0.05
  Reclaimed             55            19                12            7
  Mineralized            44                 10
  Non-mineralized       28             1                 00
  Unknown                02                 00
     A statistical analysis of these data indicate that levels in the

structures on non-mineralized land are different from those on reclaimed

land at the 99 percent confidence level as shown in Table D-4:


                                   TABLE D.4

                     Statistical Comparison of Mean Gross
              Indoor Radon Decay Product Levels by Land Category
             (Mineralized (M), Non-mineralized (N), Reclaimed (R))

        Land Use    N     Mean WL     F-test value     PR * F«
M
N
R
N
R
M
R
M
N
9
29
93
29
93
9
93
9
29
0.015
0.003
0.0.17
0.003
0.017
0.015
0.017
0.015
0.003

6.90

13.24

0.09

29.46


.0014

.0004

.7677

.0001

•Probability that the sample distributions are a product of random
variability.
                                      D-8

-------
Further, it is observed that the levels in structures on mineralized

land are not different from reclaimed land at the 90 percent

confidence level. This suggests that structures on mineralized land

may present similar indoor radon decay product levels as reclaimed

land.  Therefore, based on present information, it would be extremely

difficult to differentiate the two categories with respect to control

recommendations.



D.1.4  Evaluation by Structure Type

     The data was classified according to four structure types:

basement, slab on grade, crawl space, and trailer.  Of  the 133

structures, the average gross indoor radon decay product level for

each structure type is 0.02 WL (Basement, N=4), 0.014 WL (slab on

grade, N=102), 0.010 WL (crawl space, N=13), and 0.008  WL  (trailer,

N=14).  The sample distribution by selected working level  ranges  is

provided in Table D.5.
                              TABLE D.5
           Number of Structures  by Structure  Type  and  Mean
        Gross Indoor Radon Decay Product Level  Ranges  (N=133)

Structure Type   WL<0.01   0.0'\<.VL< 0.03    0.031 WL< 0.05    WL>. 0.05
Basement
Slab
Crawlspace
Trailer
TOTAL
2
66
10
11
89
0
20
2
2
24
2
9
1
1
13
0
7
0
0
7
                                    D-9

-------
The data for these structure types are summarized in Figure D.4.

Review of these data do not indicate any statistically significant

differences among the four structure types at the 40 percent

confidence level, as shown in Table D.6.  Therefore, though inspection

of the data suggests that basement and slab-on-grade structures have

higher indoor radon decay product levels, this cannot be shown to be

statistically significant. One of the problems in showing such

significance is the small number of structures in the categories other

than slab-on-grade.



                                TABLE D.6

              Statistical Intercomparison of Mean Gross
         Indoor Radon Decay Product Levels by Structure Type
        (Basement (b), Slab (s), Crawlspace (c), Trailer (T))

Structure type      N     Mean WL      F-test value       PR > F *
B
S
C
T
B
S
C
T
S
C
S
T
4
102
13
14
4
102
13
14
102
13
102
14
0.020
0.014
0.010
0.008
0.020
0.014
0.010
0.008
0.014
0.010
0.014
0.008

0.99


0.27

0.14

0.87

1.70


.4012


.6035

.7067

.3523

.1948

•Probability  that  the  sample  distributions  are  a  product  of random
variability
                                    D-10

-------
D
I
    O
    D
    DC
    CJ
    tr
WLX.01     03=WL< 05

      01 05

                                             SLAB-ON-GRADE
WL< 01    .03 05          01 05

       CRAWL SPACE                     TRAILER
                     Figure D.4 PERCENT DISTRIBUTION OF TLD AIR SAMPLING  MEASUREMENTS BY STRUCTURE TYPF

                                                  AND GROSS WORKING LEVEL RANGE

-------
     Of the 93 structures built on reclaimed land, the average gross




indoor radon decay product level for each structure type is 0.026 WL




(basement, N=3), 0.018 WL (slab on grade, N=70), 0.013 WL  (crawlspace,




N=7), and 0.008 WL (trailer, N=13).  The data for these structure




types is shown according to its percent distribution in Figure D.5.




     Review of these data suggests that trailers have the  least




average gross indoor radon decay product levels, followed  in




increasing order by crawl space, slab-on-grade, and basement




structures.  This appears reasonable based upon an understanding of




the characteristics of each structure type.  Trailers are  generally




constructed off the ground with good ventilation under the trailer.




When the trailer's "crawl space" is fully enclosed by cement  block or




other materials, ventilation through the space is reduced  and the




potential is increased for undesirable indoor radon decay  product




levels in the trailer.  Additions  to trailers which are constructed on




slab-on-grade foundations provide  a pathway for radon to enter  the



trailer.  It is evident therefore, that trailers generally exhibit low




indoor radon decay product levels  unless they are situated in such a




manner as to provide a pathway for radon to enter the trailer.




     The average gross indoor radon decay product level in structures




built with crawlspaces was not as  low as anticipated, probably  because




several crawlspace structures were enclosed, which restricted air  flow




under the structure or otherwise provided a pathway for radon to  enter




it.  Therefore, to minimize the radon decay product levels in such
                                   D-12

-------
o
I
cc
13
h-
O
D
QC
(—
CO
u_
O
   O
   cr
       90
       80
       70
       60
50
       40
       30
       20
        10
          WL< 01     03
-------
structures restrictions on air flow should be minimized.  For example,




piping and supports should be constructed so as not to allow for a




radon pathway.




     Slab-on-grade and basement structures exhibited the highest radon




decay product levels.  This was anticipated because of the direct




interaction between the foundation and the soil where the radon is




generated.  Clearly, these types of design present the greatest




opportunity for radon to readily enter the structure.








D.1.5  Evaluation by the Presence of Air Conditioning




     It was believed that the presence of air conditioning might have




a dramatic influence on the indoor radon decay product level because




the exchange of outdoor and indoor air would be reduced substant-




ially.  However, examination of the data, provided in Figure D.6, did




not confirm this theory.  In non-air conditioned  structures, the




average gross indoor radon decay product level was 0.016 WL  (N=47)



whereas in air conditioned structures the level was 0.012 WL  (N=86).




Other studies of the effect of ventilation on indoor radon decay



product levels (Un 78) indicated that operation of the central air




conditioning system in a structure can have a pronounced effect on




reducing  the indoor radon decay product  levels. Reduction up  to a




factor of 10 have been observed during steady state operation of the




ventilation system versus a minimal ventilation of about 0.7  air




changes per hour.  It appears that this  reduction is due to  plateout
                                   D-14

-------
WL  0!
          01  WL  03  03  WL  C5
           WITH A/C
                                 WL  - 05
                                                        W L  01
                                                                  Or WL-  03   03  WL  05    vVL   05
                                                                 WITHOUT A/C
Figure  D.6 PERCENT DISTRIBUTION OF TLD AIR SAMPl ING MEASUREMENTS BY GROSS WORKING LEVEL RANGE

-------
of radon decay products within the system as well as increased




ventilation caused by pressure differences between the indoor and




outdoor environments.  These factors seem to combine so that over an




extended time period the short term difference between air conditioned




and non-air conditioned structures are greatly eliminated.








II.  Gamma Radiation Measurements




D.2.1  General



     Outdoor gamma radiation measurements were obtained for  1102  sites




in Polk County.  The gamma surveys were performed with a  standard




portable scintillometer held one meter above the ground,  with




precautions taken to eliminate "hot spots", i.e., localized  areas of




anomalous  radiation.  The values given in the appended printout and




plotted in Figure D.7 are averages of approximately  8-10  outdoor




readings for each surveyed site.  Assuming  an average  background gamma




level  of 6yR/hr, as  established  by the EPA/DHRS  survey, approximately




97 percent of  the outdoor gross  gamma measurements  performed were



equal  to or in excess of background.  For  the  total  survey,  87 percent




were  between 6 and  15  yR/hr, with 9  sites  or  about  one percent, in




excess of  30  yR/hr.








D.2.2  Geographical Distribution




      The  gamma survey was  performed  in nineteen cities and towns in




 the  County with a predominant  number of surveys (853)  being performed




 in Lakeland,  Mulberry,  Winter  Haven and Bartow,  as shown in Table D.7.
                                   D-16

-------
   100
C/5
UJ
tr
O

oc
u
OC
    90
    80
    70
    60
    50
    40
    30
    20
    10
                                               N-1102
                   6 10
                           11 15
                                                             >30
                                   1620     21-25    26-30


                                     OUTSIDE GAMMA (jjR'hri



Figure D.7  PERCENT DISTRIBUTION OF OUTSIDE GAMMA RADIATION MEASUREMENTS
                                     D-1 7

-------
                                TABLE D.7

      NUMBER OF STRUCTURES BY CITY AND SPECIFIC OUTDOOR GAMMA RANGE

     City     0-10yR/hr   11-20yR/hr   21-30yR/hr     30yR/hr       N

                                                                    15
                                                                     1
                                                                    67
                                                                     5
                                                                    25
                                                                    23
                                                                     1
                                                                    23
                                                                    23
                                                                    30
                                                                    37
                                                                     1
                                                                     1
                                                            2      616
                                                                    35
                                                            3      101
                                                                     5
                                                                    24
                                                                    69
                                                            5      1102

Figure D.8 provides a geographical representation of this data with the

number of sites and average gamma range for each city noted.  The  "Pebble

55-70 percent BPL" boundary denotes the approximate extent of the

phosphate mineralized zone.  As the site data  illustrates, all of  the

measurements except for one in excess of 10 UR/hr were located on

mineralized land (reclaimed or otherwise).  Average measurements in

excess of 20 yR/hr (53 sites or about 5 percent  of the sites) were

obtained in Bartow, Eaton Park, Fort Meade, Lakeland, Mulberry, and

Pierce.
Auburndale
Babson Park
Bartow
Bradley
Davenport
Dundee
Eagle Lake
Eaton Park
Fort Meade
Frostproof
Haines City
Highland City
Lake Alfred
Lakeland
Lake Wales
Mulberry
Pierce
Polk City
Winter Haven
TOTAL
15
1
44
4
25
22
1
18
9
23
37
1
1
466
35
41
2
24
69
838


19
1

1

3
10
7



127

47
2


217


4




2
4




21

10
1


42
                                   D-18

-------
                             NO. OF
                             STRUCTURES
                             SAMPLED
                          AVG. OUTDOOR
                          GAMMA LEVEL
                          (GROSS)
2675
025
 r*-1 STRUCTURE SAMPLED

    10/^R/hr
                                         21-30AiR/hr
LAKE COUNTY
ORANGE COUNTY
                                                               OSCEOLA COUNTY
          EATON PARK    WINTER HAVEN
  MULBERRY    BARTOW
HARDEE COUNTY
                                                                 HIGHLANDS COUNTY
     Figure D.8  AVG OUTDOOR GAMMA RADIATION DISTRIBUTION (GROSS) FOR
                 POLK COUNTY, FLORIDA (NM102)
                                     D-I9

-------
D.2.3  Indoor/Outdoor Gamma Radiation Ratio

     Indoor gamma levels are measured in a manner similar to the outdoor

survey.  For the indoor survey, a minimum of one reading was made in each

room of a structure with at least 10 readings per 1000 square feet of

floor space.  The ratio of the average indoor gamma level to the average

outdoor gamma level would be expected to provide a general measure of  the

shielding.characteristics of a structure type.  As shown in Table D.8,

four structure types were evaluated: basement, slab-on-grade, crawl

space, and trailer.  In calculating these ratios, the cosmic radiation

contribution, estimated at 4 pR/h, is subtracted from the indoor and

outdoor values.

                                   TABLE D.8
                   Average Ratio of Indoor Gamma to Outdoor
                     Gamma Measurements by Structure Type
                     (minus cosmic contribution of 4 yR/h)

                               Average Ratio
            Structure Type     Indoor/Outdoor   # of Structures

            Basement                .79                13*
            Slab-on-grade           .83              765**
            Crawl Space             .91                60+
            Trailer                 .90              215+

 * 2 structures have no ratio  given
**32 Structures have no ratio  given
 +15 Structures have no ratio  given

     For  the total sample of  1102 structures, an average  ratio  of  0.9

was  calculated for all four structure types.  The  lack  of

differentiation is not unexpected recognizing that  approximately

two-thirds  of  the  structures  had outdoor gamma  readings of  less than
                                   D-20

-------
10 yR/hr.  These readings roughly approximate the observed background




level of 6yR/hr, thereby leading to a high "noise"  level  by  which  a




representative relationship between outdoor to indoor gamma  is




masked.  This effect is supported by ratio calculations for




observations equal to or greater than 10 and  15 yR/hr, respectively.




As shown in Tables D.9 and D.10, the average  ratio  for all structure




types is less for these observations.  The ratio for basements  and




slabs is as much as a factor of two less than the total sample, which




corresponds to an attenuation factor of 0.4 for a four inch  layer  of




concrete (6 percent porosity). Accepting this premise, structures  with




underlying layers of concrete appear to be between  two and three times




as effective in reducing gamma flux than those that do not (i.e.,




crawl space and trailers, with a underlying layer of air  and




flooring).   In summary, inside gamma was greater than outside gamma




for 80 sites (7 percent), less than outside gamma for 606 sites (55



percent), and about equal for 404 sites (38 percent).
                                  D-21

-------
                                  TABLE D.9

                A.  Average Ratio of Indoor Gamma  to Outdoor
                  Gamma Measurements by Structure  Type  for
               Observations equal to or greater  than  10  R/hr
             (Basement  (B), Slab  (S), Crawlspace  (C), Trailer  (T))
                    (minus cosmic contribution of  4  R/h)
        Structure Type

              B
              S
              C
              T
Average Indoor/Outdoor

      0.44
      0.53
      0.77
      0.80
              # of Structures

                      4
                    257
                     28
                     52
               B.   Statistical  Comparison of Average Gamma Ratios
              Type
Avg Ratio
B
S
C
T
S
C
T
C
T
S
C
4
257
28
52
257
28
52
28
52
257
28
0.44
0.53
0.77
0.80
0.53
0.77
0.80
0.77
0.80
0.53
0.77
F-test Value
                                              28.47
PR   F*
                                0.0001
                                              42.19


                                               0.32


                                              28.40
                                0.0001
                                0.5727
                                 0.0001
"Probability that the sample distributions are a product of random
variability
                                   D-22

-------
                               TABLE D.10

     A.  Average Ratio of Indoor Gamma to Outdoor Gamma Measurements
       by Structure Type for Observations Equal to or Greater than
           15 yR/hr (Basement (B), Slab (S), Crawl Space (C),
           Trailer (T))  (minus cosmic contribution of 4 yR/h)

       Structure Type     Average Indoor/Outdoor      # of Structures

            B                    0.42                          1
            S                    0.41                         87
            C                    0.81                         13
            T                    0.79                         22

         B.  Statistical Intercomparison of Average Gamma Ratios

           Type     N    Avg. Ratio   F-test Value    PR > F«

             B       1      0.42
             S      87      0.41         45.50         .0001
             C      13      0.81
             T      22      0.79

             S      87      0.41
             C      13      0.81         67.14         .0001
             T      22      0.79

             C      13      0.81          0.03         .0001
             T      22      0.79

             S      87       .41         54.90          .0001
             C      13       .81

•Probability that the sample distributions are a product of random
variability
                                   D-23

-------
         100 i-
          90 -
c
I
ro
                                                      0 10
                                                    ,11 R/HR
               RECLAIMED

                      Figure D.9
•Ranges not shown indicate N=0
                                                   11 20
                                                  PR/HR

                                               MINERALIZED
  010     1120
 JJR/HR   ^JR/HR

NON MINERALIZED
 0 10
l R/HR
  11 20
 >JR/HR

UNKNOWN
 21 30
PR/HR
                                               PERCENT DISTRIBUTION OF GAMMA EXPOSURE RATE BY LAND
                                               CATEGORY*

-------
D.2.4  Evaluation by Land Category

     As part of the overall survey, outdoor gamma measurements were

evaluated according to the land category of the site.  Four primary

categories were delineated on the basis of the presence or absence of

phosphate matrix, and past mining and reclamation: reclaimed raining

sites, mineralized sites, non-mineralized sites, and sites of unknown

designation.  In Table D.11 and Figure D.9, a distribution of

measurements in increasing increments of 10 yR/hr is given for these

categories.

     A statistical (F-test) intercomparison of the data shows a probable

difference between the three distributions (excluding the "unknown"

category) at the 99 percent confidence level. This evaluation, summarized

in Table D.12, suggests that on the basis of the sample data collected,

these land categories have statistically unique gamma distributions

associated with them.

                               TABLE D.11

            Outdoor Gamma Survey Distribution of all structure
                        • sites by Land Category

               Range of Outdoor Gamma Measurement ( y R/hr)
     Use               N   0-10   11-20   21-30   >30   Average

Reclaimed (R)        672    429    198      40     5     10.7
Mineralized (M)      102     97      5       0     0      7.2
Non-Mineralized (N)  300    292      8       0     0      5.6
Unknown (U)           28     20      7       10
TOTAL               1102    838    218      41     5
                                      D-25

-------
M
N
R
M
R
N
R
M
N
102
300
672
102
672
300
672
102
300
7.0
5.8
10.7
7.0
10.7
5.8
10.7
7.0
5.8

39.64


244.34

139.26

55.35
                                  TABLE D.12

                    Statistical Comparison of Gamma Survey
                   Distribution for Selected Land Categories
              (reclaimed (R) mineralized (M) non-mineralized (N))

               Use     N     Avg Gamma    F test-Value     PR >F*
                                                           0.0001
                                                           0.0001
                                                           0.0001
                                                           0.0001

•Probability that the sample distributions are a product of random
variability
D.2.5  Evaluation by Structure Type and Land Category

     Indoor gamma exposure was evaluated on the basis of both

structure type and land category.  As a preponderance of structures

(677) in the survey are located on land identified as being reclaimed,

the gamma measurement distribution for the four structural categories

were taken for structures so located, as provided in Figure D.10.



III. Track-Etch Measurements

     Radon decay product levels were estimated in 153 structures with

track-etch film.  In this pilot study, the film was placed in a
                                  D-26

-------
       100 i—
D
10
                                                   N 426
                                                                                                             N 20?
              010
1120
 BASEMENT
                                           0 10
                                                                                                      0 10
                                                                                                            1120    2130
                                                                                                              TRAILER
                                    1120                   010   1120   2130
                                   SLAB ON GRADE                  CRAWL SPACE
                                        INDOOR GAMMA EXPOSURE (;iR/HR GROSS)
Figure D.10 PERCENT DISTRIBUTION FOR INDOOR GAMMA EXPOSURE RATE B\ STRUCTURE TYPE FOR RECLAIMED LAND
   • RANGES NOT SHOWN INDICATE NO

-------
structure for at least a year, after which a representative count was




taken of the "etches" caused by alpha energy deposition.  This count




is translatable into radon decay product levels (see Appendix B of




this report).




     In Figure D.11, a percent distribution of working level estimates




in increments of .006 WL is provided.  Approximately 70 percent of




these measurements were less than or equal to 0.03 WL, with 7 percent




in excess of 0.09 WL.
                                   D-28

-------
          35
          30
          25
O
 I
10
vD
       u
          20
                                                                               N 1 53
          15
       o
       cr
          10
              WL *~ 006  012
                                018    .024     030     036     042     048    .054     060     066     .072     078

                                                      TRACK ETCH DATA IN INCREMENTS OF OOG WLMMTfRVtNINC., RAMu F RS'
090  VVL  • 090
                      Figure D.ll  PERCENT DISTRIBUTION OF EPA TRACK-ETCH DATA BY GROSS WORKING LEVEL RANGE

-------
ANNEX

-------
                                             ANNEX KEY
"CLASS"
CLASSIFICATION
"TYPE"
TYPE STRUCTURE
"LEVELS"
FLOOR LEVEL
"MATRIAL"
MATERIAL
"A-C"
AIR CONDITIONING
0. Vacant Lot

1. Residence
     Single Family

2. Multiple
     (4 families)

3. Apartment (Gt 4)

4. Motel, hotel

5. Single business

6. Multiple business

7. School

8. Church

9. Other
1.  Basement

2.  Slab-on-grade

3.  Crawl space

4.  Trailer

5.  Unknown
0. Unknown     0. Unknown      0.

1. One floor   1. Masonry      1.

2. Two floors  2. Non-masonry  2.

                               3.

                               4.

                               5.

                               6.

                               7.


                               8.
                                                                           A.

                                                                           B.
Unknown

Yes

No

Yes, never used

Central always

Central seasonally

Central occasionally

Window recirculating
  always

Window recirculating
  seasonally

Window recirculating
  occasionally

Window makeup always

Window makeup
  seasonally

Window makeup
  occasionally
"AP-Mean": Air Pump Mean Working Level (WL)
"TE-Mean": Track Etch Mean Working Level (WL)
"GF-Gamma": Mean Indoor Ground Floor Gamma Exposure Rate  ( yR/hr)
"Out-Gamma": Mean Outdoor Gamma Exposure Rate  ( yR/hr)
"USE": "R"-Reolaimed, "M"-Mineralized, "N"-Non-mineralized,  "U"-Unknown  Land
                                                      Use

-------
                       AIK PUMP ANfl TRACK ETCH AVERAGES  ANC  ALL  LOCATION DATA
LCCATION  AP_MEAN   TE_MEAN   GF_GAMMA  OUT_GAMA  USE  CLASS   TYPE  LEVELS  MATRIAL  A_C  CITYNAME
 70C50
 7CC51
 70052
 70C53
 70054
 70055
 70056
 70057
 70058
 70059
 70060
 70061
 70062
 7C063
 7CC64
 70065
 70C66
 70067
 7CC68
 70069
 7CC70
 70C7L
 70072
 7CC73
 70C74
 70075
 7CC76
 70C77
 70C78
 70 079
 70080
 7CC81
 7CC82
 7CC83
0.0075
C.0173
0.0626
O.C599
C.0226
C.01C2
0.0083
C.0209
0.0091
C.0096

C.0151
C.0089
C.OG8V
C.0223
0.0152
C.0086
0.0069
G.U202
0.0340
C.U147
0.0047
C.0179
0.0316
C.UJ82
C.0042
C.0183
0.0040

C.1248
0.0790
C.0248
0.0405
C.0619
0.0415
C.0029
0.0251
12
9
3
6
4
10
7
5
7
5
6
6
8
8
7
7
7
5
7
8
4
4
8
7
5
18
16
10
15
10
17
9
20

10
11
12
7
10
11
15
12
12
9
11
14
13
12
11
10
9
10
11
8
12
9
8
8
8
25
26
14
11
12
16
7
9
3
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
K
R
9
9
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
L
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
3
3
1
1
1
1
1
1
L
1
1
L
1
1
2
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
7
1
2
2
2
5
5
6
6
6
6
0
5
6
6
6
5
6
6
6
5
6
6
6
6
6
6
6
5
6
6
6
6
6
6
0
2
2
2
LAKELAND
EATON PARK
LAKELAND
LAKELAND
EATON PARK
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
EATON PARK
EATON PARK
EATON PARK
EATON PARK
EATON PARK
LAKELAND
BARTOW
BAHTOW
BARTGW
BARTOW
BARTOW
BARTOW
BARTOW
FT MEADE
FT MEADE

-------
AIR PUMH AND TKACK ETCH AVERAGES  ANC  ALL  LOCATION  DATA
LCCATILN
7CC£4
7CC€6
K C 6 7
7CCfc8
7CC89
7CC90
7CC91
7CC92
7CC93
7CC94
7CC95
7CC96
7CC97
7CC98
7CC99
701CO
7C1C1
7C102
7C1C3
7C1C4
7C1C5
701C6
7C1C7
7G1C8
7C1C9
7C110
7C111
7C112
7C113
7C114
7C115
7C116
7C117
AP_MEAN
0.0176








0.0322



O.IC45






C.0365

0.0673


0.0721

G.GC36





N  oF_GAMMA  CUT_GAPA  USE  CLASS   TYPE   LEVELS   MATRIAL  A_C  CITYNAME
O.OC12

O.OC17
C.OC68
O.OC37
0.0227
O.GC89
0.0208
0.0012
0.0107
O.U46fa
0.0598
0.0170
0.0217

O.OC13
0.0187
O.OC57
0.0250
0.0157

0.0186
0.0939
0.0768
C.OC87
O.OG32
0.0839
O.OG82
O.OC99
0.0252
0.0210
O.OC48
0.0155
0.0900
27
15
15
28
7
14
9
15
8
8
12
16
14
15
20
3
5
12
7
9
9
10
15
15
11
12
12
16
9
19
16
16
5
11
29
23
16
29
1 7
18
14
16
£
5
23
28
24
24
25
8
13
2C
15
7
14
2 1
3C
31
23
2C
22
17
23
33
15
15
9
23
U
R
R
R
R
R
ft
R
R
R
R
R
R
R
R
U
U
U
U
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
9
1
1
1
1
1
1
9
1
1
1
1
8
3
3
3
3
2
2
2
2
1
2
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
3
2
2
1
I
1
1
1
1
1
1
1
1
I
1
1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
2
2
2
3
1
1
1
1
1
I
1
1
1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
1
1
1
2
0
2
6
2
2
2
2
1
6
6
6
6
6
0
6
6
6
5
6
2
6
6
6
2
6
6
6
0
6
6
2
2
6
                                                                FT MEADE
                                                                FT MEADE
                                                                FT MFADE
                                                                FT MEAOE
                                                                BARTCW
                                                                BARTGW
                                                                BARTGW
                                                                BARTGW
                                                                MULBERRY
                                                                MULBERRY
                                                                LAKELAND
                                                                LAKELAND
                                                                LAKELAND
                                                                LAKELAND
                                                                LAKELAND
                                                                AUBURNDALE
                                                                LAKELAND
                                                                LAKELAND
                                                                LAKELAND
                                                                LAKELAND
                                                                LAKELAND
                                                                LAKELAND
                                                                LAKELAND
                                                                LAKELAND
                                                                LAKELAND
                                                                LAKELAND
                                                                LAKELAND
                                                                MULBERRY
                                                                MULBERRY
                                                                MULBERRY
                                                                MULBERRY
                                                                PIERCE
                                                                BRADLEY JUNCTION
                                                                PIERCE

-------
A IK PUMP AND TRACK fcTCH  AVERAGES  ANC ALL LOCATION DATA
CCATIuN
7C118
7C119
7C120
7C121
70122
7G123
7C124
7C125
7C126
7C127
7C128
70129
7C130
7C131
7C132
7C134
7C135
7C136
7C137
7C138
7C139
70140
7C141
7C146
7C147
7C148
7C149
7C150
70151
7C152
7C166
7C167
7C168
7C169
AP_MEAN T£_M£AI
0.0106 0.0050
0.0565
0.0702
0.0277
0.0162
0.0154
0.012C

0.0154
0.0053
0.0057

0.0096
0.0297
0.0166
0.0013 O.J069
C.COC8 O.UG89
O.C013 0.0026
O.C009 0.0143
0.0027
0.0250
0.0141
0.0089


0.0102
0.0034
0.0088
0.0052
0.0198
0.0666
0.1256

O.C252 0.0203
     GF_GAMMA  uUT_GAMA   USE   CLASS  TYPE  LEVELS  MATRIAL   A_C   CITYNAME

                                                                   PIERCE
                                                                   LAKELAND
                                                                   LAKELAND
                                                                   LAKELAND
                                                                   MULBERRY
                                                                   LAKELAND
                                                                   LAKELAND
                                                                   LAKELAND
                                                                   LAKELAND
                                                                   LAKELAND
                                                                   LAKELAND
                                                                   LAKELAND
                                                                   LAKELAND
                                                                   LAKELAND
                                                                   LAKELAND
                                                                   WINTER HAVEN
                                                                   LAKE ALFRED
                                                                   EAGLE LAKE
                                                                   KINTEP HAVEN
                                                                   WINTER HAVEN
                                                                   HAINES CITY
                                                                   LAKE HALES
                                                                   BA8SCN PARK
                                                                   AUBURNDALE
                                                                   AUEURNOALE
                                                                   AUBUKNDALt
                                                                   PCLK CITY
                                                                   BARTOk
                                                                   FT MEAOE
                                                                   FT MEADE
                                                                   LAKELAND
                                                                   LAKELAND
                                                                   LAKELAND
                                                                   MULBERRY
7
12
14
8
6
14
6
6
5
7
6
12
14
15
13
3
3
4
4
3
3
3
3
3
3
3
4
7
10
6
9
18
15
10
8.0
17. C
15.0
15. C
13.0
2C.O
16, C
s.o
7.0
1C.O
1C.C
35.0
17, C
1£,C
15.0
6.0
6.0
7.C
6.0
5,5
6.C
fc.C
6.C
3.C
4.0
8.0
4.0
7.0
7.0
6.C
16.0
13.0
17.0
11. C
R
R
R
R
R
R
R
R
K
R
R
R
R
R
R
N
N
N
N
K
N
N
N
N
N
N
N
U
M
N
M
M
M
M
1
1
1
9
1
1
1
1
1
1
1
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1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
9
i
1
1
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1
9
2
2
2
2
2
2
2
3
3
2
1
2
2
2
2
2
2
1
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2
3
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2
3
3
3
1
3
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£.
2
2
3
2
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
2
1
1
I
1
1
1
I
1
1
I
I
I
1
1
0
1
1
1
1
1
1
2
2
1
1
2
1
1
2
1
1
1
1
1
2
1
1
1
1
1
2
1
2
1
1
I
3
1
2
6
6
5
5
6
6
2
2
6
6
0
6
6
6
5
2
2
6
6
5
6
6
2
0
6
2
5
6
6
6
6
0
5

-------
      AIR t^UMP ANi) TRACK ETCH AVERAGES  ANC ALL LOCATION JATA
TE_HEAN  GF_GAMMA  CUT_GAMA  USE   CLASS   TYFfr  LEVELS  MATRIAL  A_C  CITYNAME
7C17C
7C171
7C172
7C173
7C174
7C175
7C176
7 C 1 7 7
7C178
7C179
7C180
7C181
7C182
7C183
7C1C4
7C185
7C186
7C187
7C188
7C189
7C190
7C191
7C1S2
7C3CO
7C3C1
70302
7C3C3
7C3C4
7C3C5
703C6
1C3C7
7C3C8
703C9
70310
O.CC65 0.0192
0.0604
0.0329 0.0288
0.0135
0.0338
0.0022 0.1
-------
                         AIR PUMP ANO TRACK ETCH AVERAGES AND ALL LOCATION DATA
LCCATICN  AP_MEAN  TE_KEAN  GF_GAMMA  CUT_GAMA  USE  CLASS  TYPE  LEVELS  MATRIAL  A_C  CITYNAME
 7C3H
 7C312
 7C313
 7C314
 7G315
 7C316
 1C317
 7C318
 70319
 70320
 7C321
 7C322
 7C323
 7C324
 70325
 7C326
 70327
 7C330
 7C331
 7C332
 10333
 7C334
 7C335
 1C336
 70337
 7C338
 70339
 7C350
 70351
 7C352
 7C353
 7C354
 7C355
 7C356
0.0296
0.0387
0.0232
0.01L8
0.0795
0.13L1
0.0554
0.0778
0.1373
0.0915


0.0872
0.0£79
0.0567
O.OC49
O.OC47
O.OC78
0.0074
O.OC60
O.OC53
O.OC77
0.0550
O.OC26
0.0072
0.0226
O.OC96
0.0830


0.0321
0.0456

0.0159
6
7
7
6
8
10
8
7
5
6
5
8
10
8
7
4
3
3
4
8
8
6


6
15

5
7
13
8
8
6
6
14
15
16
20
17
3C
18
13
13
3C
8
15
25
25
16
6
5
4
13
11
14
9
14
6
9
12
13
7
6
28
24
16
21
15
ft
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
I
1
1
5
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
2
3
2
2
2
2
2
3
2
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
2
1
1
1
1
1
2
1
1
1
1
2
1
1
1
0
1
5
5
6
3
4
1
5
5
4
5
1
1
1
1
1
1
2
2
1
1
1
1
1
1
1
1
1
1
1
6
1
1
6
3
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
BARTCW
BARTOW
BARTOW
BARTCW
BARTOW
BRADLEY JUNCTION
BRADLEY JUNCTION
BARTGW
BARTOW
BARTOW
BARTOW
BARTOW
BARTOW
BARTOW
BARTOW
BARTOW
PIERCE
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND

-------
                       AIK PUMP AND TRACK ETCH AVERAGES  ANC ALL LOCATION DATA
LCCAT10N  AP_MEAN   TE_MEAN  6F_GAMMA  OUT_GAMA  USE   CLASS  TYPE  LEVcLS  MATRIAL   A_C   CITYNAMc
 70357
 70358
 70359
 70360
 70361
 70362
 70363
 70367
 70401
 7C402
 70403
 70406
 70407
 70408
 70409
 70410
 70411
 70412
 704 13
 70414
 70415
 70416
 70417
 70418
 70419
 70420
 70421
 70422
 70423
 70424
 70425
 70426
 70427
 70428
          C.0926
          0.0837
0.0076
0.0043
0.0035
 8
 6
11
 9
 7
 6
10
 6
 7
 a
 3
 6
 7
 6
 7
 8
 9
 9
 9
10
 7
 7
 8
 7
 7
 6
 7
10
12
 8
 6
 6
 6
 6
22
15
25
20
23
IS
11
6
11
9
9
7
7
7
7
8
9
10
11
1C
7
7
9
6
7
7
7
11
11
8
6
6
6
7
R
R
R
R
R
R
R
R
R
R
R
R
R .
R
R
R
R
R
R
R
R
k
R
K
R
K
R
R
R
R
R
R
R
R
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
1
1
1
1
1
1
1
1
1
1
1

1
1

1
1
1
1
1
1

1
1
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2

2
2

2
2
2
2
2
2

2
2
2
2
2
2
2
2
2
2
2
2
6
1
1
6
1
6
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
I
1
I
I
1
2
1
I
I
1
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
AUBUKNQALE
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND

-------
                      AIR  PUMP  AND TRACK ETCH AVERAGES  AND  ALL  LOCATION DATA

LOCATION  AP_MEAN   TE_MEAN   GF_GAMMA  CUT_GAMA  USE  CLASS   TYPE   LEVELS  MATRIAL  A_C   CITYNAME

 70429
 70430
 70431
 7C432
 70433
 70434
 70435
 70436
 70437
 70433
 70439
 70440
 7044L
 70443
 70444
 70445
 70446    0.0046
 10447
 70448
 70449
 70450
 70451
 70452
 70455
 70454
 70455
 7C456
 70457
 70458
 70459
 70460
 70461
 70462
 70463
6
6
5
5
10
9
7
9
10
6
7
7
7
7
7
6
7
7
8
12
12
12
6
6
8
7
8
6
7
7
6
6
6
7
6
6
5
5
11
9
8
9
11
6
7
6
8
7
7
6
7
7
9
14
13
13
6
6
8
7
7
6
7
7
7
6
6
7
U
U
U
U
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4'
4
4
4
4
4
4
4
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1

1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2

2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
I
1
1
2
2
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND

-------
                     Alk  PUMP  AND TRACK ETCH AVERAGES AND  ALL  LOCATION  DATA
LOCATION  AP_MEAN   TE_/*tAN   GF_GAMMA  CIT.GAMA  USE  CLASS  TYPE   LEVELS  MATRIAL  A_C  CITYNAME
 7C464
 70 46 5
 7U466
 7C467
 7C463
 7C469
 7U47U
 7G471
 70472
 70473
 70474
 7C475
 70476
 7C477
 7C478
 7C479
 704dO
 7C481
 7C482
 70483
 7G4d4
 70435
 70486
 704b7
 70488
 70489
 70490
 70491
 7C492
 70493
 7C494
 70495
 7C496
 7C497
C.0033
7
6
6
6
6
7
7
6
6
6
5
6
6
8
10
6
6
7
6
7
6
6
6
6
7
7
7
7
7
6
6
5
6
6
7
6
6
6
6
7
7
6
6
7
6
6
6
7
7
7
7
7
7
7
7
7
6
7
7
7
8
7
7
6
6
fc
7
7
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
L
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
1
1
1
1
1
1
1
L
1
1
1
1
1
1
L
1
1
1
1
1
1
L
1
1
1
1
1
1
1
1
1
1

1
2
2
2
2
2
4
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2

2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
L
1
1
1
1
1
1
1
1
1
1
1
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND

-------
                     AlK PUMP  AND  TRACK  ETCH  AVERAGES AND 4LL LOCATION DATA
LCCATIGN  AP_MEAN  T£_MEAN  GF_GAMMA   CLT_GAMA  USE  CLASS  TYPE  LEVELS  MATRIAL   A_C   CITYNAME

 70498
 7C499
 70500
 70501
 70502
 70503
 7C504
 70505
 70506
 70507
 70508
 70509
 70510
 70511
 70512
 70513
 70514
 70515
 70516
 70517
 70518
 7C519
 70520
 70521
 70522
 7C523
 70524
 70525
 70526
 70527
 70528
 70529
 70530
 70531
5
5
5
5
5
5
6
f>
5
6
5
8
5
5
5
6
5
5
5
6
5
5
5
5
6
5
5
20
8
7
6
5
5
5
5
6
6
6
5
6
5
6
6
6
5
8
6
6
6
6
6
5
5
8
5
5
6
6
6
6
5
8
8
7
6
6
5
6
R
K
R
R
R
R
R
R
R
R
R
R
R
K
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
1
1
1
1
1
1
I
1
1
1
1
1
1
1
i
1
1
1
1
1
1
i
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
i
1
1
1
1
1
1
1
1
1
1
I
1
1
1
I
LAKELAND
LAKtLAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKtLAND
LAKELAND
LAKELAND

-------
                      AIR PUMP AND  TXACK  ETCH AVERAGES  ANC  ALL LOCATION DATA
LOCATION  AP_MEAN  Tfc_MEAN  bF_GAMKA   CUT_GAMA  USE  CLASS   TYPE  LEVELS   MATRIAL  A_C  CITYNAME
70532
70533
70534
70535
70536
70537
70538
7053S
70540
70541
70 542
70543
70544
70545
70546
70547
7C548
70549
70550
70551
7C552
70553
70554
70555
70556
70557
70558
70559
70560
70561
70562
70563
70564
7C565







C.0384


















0.0858



C.0106
C.0313


7
7
7
7
6
7
7
13
7
3
7
9
8
7
8
7
7
6
6
7
7
7
11
7
7
7
7
6
8
7
7
7
7
7
8
6
8
3
7
8
8
8
1C
12
11
11
a
10
11
9
8
7
8
8
8
7
15
7
8
8
10
8
S
11
15
16
7
8
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
k
R
R
R
R
R
R
R
R
K
R
R
K
R
R
R
R
1
1
1
1
1
3
3
1
1
1
I
1
3
3
1
I
1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
4
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
1
1
1
2
I

1
1
1
1
2
1
1
1
1
1
1
1
1
I
1
1
1
1

1
1
1


1
1
2
1
1
1
1
I
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
i
1
1

1
1
1


1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND

-------
                     AIR  PUMP  ANO  TKACK ETCH AVERAGES AND /*LL LOCATION OATA
LOCATION  AP_MEAN  TE_MEAN   GF_GA^A   CUT_GAMA  USE  CLASS  TYPE  LEVELS  MATRIAL  A_C  CITYNAHE
II
70566
70567
70568
70569
7C570
7G571
70572
7C573
70574
70575
70576
70577
70578
7G579
70580
70581
70582
70583
70584
70585
70586
705&7
7C588
70589
7C590
70591
7C592
70593
70594
7C595
70596
70597
70598
70599




G.0066


0.0086

C.0042



0.0064
0.0089



C.0168

0.0177
C.0108












                               7
                               7
                               7
                               6
                               6
                               6
                               6
                               6
                               6
                               6
                               7
                               6
                               7
                               6
                               7
                               6
                               6
                               6
                               7
                               6
                               6
                               7
                               a
                               6
                               7
                               7
                               7
                               6
                               7
                               6
                               6
                               7
8
7
8

7
7
8
6
6
7
7
8
9
6
6
7
7
6
7
8
11
7
8
9
8
9
8
8
8
8
8
6
6
8
R
R
R
R
R
R
R
k
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
3
2
2
2
1
1
3
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
1
1

1
1

1

1
1
1


1
1
2

1


1
1
1
I
2
1
1
2
2
1
I
1
1
1
1
1

1
I

1

1
1
1


1
1
1

1


1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND

-------
                     Alk PUMP  AND  TRACK  ETCH  AVERAGES  AND *LL LOCATION DATA
12
LOCATION  AP_MEAN  TE_MEAN  GF_GAMMA   CUT_GAMA   USE  CLASS  TYPE  LEVELS  MATRIAL  A_C   CITYNAME
7C6UC
7C601
7C602
7C603
7C604
7C605
70606
7C607
70608
7C609
70610
70611
70612
7C613
70614
70615
70616
7G617
70618
7C619
7C620
7C621
70622
70623
70624
70625
7C626
70627
70628
70629
70630
70631
70632
70633




C.0066




0.0091



0,0056

0.0034












C.C096
0.0041


0.0138

7
7
5
5
5
6
6
8
7
7
7
7
8
7
6
7
7
8
7
8
7
6
6
8
10
9
8
8
8
8
7
7
6
7
10
10
7
5
6
6
6
9
10
11
11
13
9
12
6
12
10
10
10
10
8
6
9
12
11
12
9
9
9
11
9
9
10
10
R
R
R
R
R
k
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
K
R
R
R
1
3
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
I
1
I

1
1
1
1

1
1
1

1

1
1
1
1
1
1
1
1
1
1
1
1


1
1

1
1
1
1
1

1
1
1
1

1
1
I

1

1
1
1
1
1
1
1
1
1
I
1
I


1
1

1
1
1
1
1
1
1
1
I
I
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND

-------
                      AIR PUMP AND TRACK ETCH  AVERAGES ANC *LL LOCATION  DATA

LOCATION  AP_MEAN   Tt.MtAN  GF.GAMMA  CUT.GAMA   USE  CLASS  TYPE  LEVELS  MATRIAJ.  A_C  CITYNAME
13
70634
7C635
7C636
7C637
7C638
70639
7C640
7C641
7C642
70643
70644
7C645
7C646
70647
7C648
7C649
7C650
70651
7C652
7C653
7U654
7C655
70656
70657
7C658
7G659
70660
7C661
70662
7C663
70664
7C665
70666
70667


C.0050
0.0044













0.0058

C.0040












0.0048

                                 8
                                 7
                                 7
                                 6
                                 7
                                 9
                                 8
                                 7
                                 6
                                 8
                                 9
                                 8
                                 8
                                 7
                                 7
                                 8
                                 7
                                 7
                                 3
                                 6
                                 6
                                10
                                10
                                 6
                                 8
                                 6
                                 7
                                 7
                                10
                                 7
                                 7
                                 7
                                 6
                                 7
11
9
10
10
11
8
10
9
6
9
18
11
10
12
10
13
10
11
12
7
8
9
1C
6
7
7
8
7
11
8
8
7
5
8
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1


1
1
1
1
1
1
1
1
1
1
1
1
1

1

1
1
1
1
1
1
1
1
1
1
1
1

1
1
1


1
1
1
1
1
1
1
1
1
1
1
1
1

1

1
1
1
1
1
1
1
1
1
1
1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND

-------
                     AIR PUMP AND TRACK  ETCH  AVERAGES  AND *LL  LOCATION DATA
LOCATION  AP_MEAN  TE_NEAN  GF_GAMMA  CUT_GAMA   USE   CLASS  TYPE  LEVELS  MATRIAL  A_C  CITYNAME
7C668
7C669
70670
70671
7C672
7C673
70674
7C675
70676
7C677
70678
7C679
7C680
7C681
70682
70683
7C684
70685
70686
7C687
70688
70689
7C690
7C691
7C692
70 693
7C694
7C695
70696
70697
7C698
70699
70700
7C701








0.0046
0.0052


0.0039

0.0063
0.0053



0.0075
0.0025







C.0055





7
7
8
8
7
6
6
6
10
6
7
6
7
6
7
7
7
7
7
7
8
8
8
8
8
10
7
8
7
7
7
6
7
7
7
8
10
7
7
7
7
6
9
8
9
7
6
6
12
9
9
8
10
8
9
9
9
9
8
11
10
12
10
8
8
7
7
8
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
I
2
1
1
*
4
4
4
4
4
2
2
4
4
4
4
4
4
1
1
1
1
1
1
1
1


1
1

1


1
1
1


1
1
1
1
1
1
1

1
1
1
1
1
1
1
1
1
1
I
1
1


1
1

1


1
1
1


2
2
2
2
2
1
1

2
2
2
2
2
1
1
1
1
1
1
2
1
1
2
1
1
1
1
1
1
1
1
2
1
2
2
1
1
1
1
1
1
2
1
1
1
1
1
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND

-------
                       AIR PUMP AND TRACK ETCH  AVERAGES AND ALL LOCATION DATA                         15

LCCAFIGN  AP_MEAN   TE.rtEAN  GF_GAMMA  ObT_GAMA   USE   CLASS  TYPE  LEVELS   MATRIAL  A_C  CITYKAME

 7C7G2
 70703
 7C7G4
 70705
 707Cf
 707C7
 7C7C8    C.0131
 70709
 7C7LU
 70711
 7C712
 7C713
 70714
 70715
 70716
 70717
 7C71B    C.OC79
 7C719
 70720
 7C721
 70722
 7C723
 70724
 7G725
 70726
 70727
 70728
 70729
 70730
 70731
 7J732
 70733
 7C734
 70735    O.OG84
8
0
6
8
6
8
a
9
10
6
7
12
15
17
8
13
7
10
9
7
8
12
10
8
8
13
6
6
8
7
12
9
6
6
S
9
6
7
6
8
e
11
13
6
8
15
20
21
13
15
8
10
7
7
7
12
11
9
10
16
8
7
7
9
13
6
7
1C
R
R
a
R
R
H
R
k
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
4
4
4
4
4
2
2
2
2
4
4
4
4
4
4
4
2
2
2
2
2
4
4
4
4
4
2
4
2
2
4
2
2
2
1
1
1
1
1
1

1
1
1
1
1
1
1
1
1

1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1

2
2
4
2
2
1

1
1
2
1
2
2
2
2
2

1
1
1
1
2
2
2
2
2
1
1
1
1
2
1
1

1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
2
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
2
1
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
EATON PARK
EATON PAKK
EATON PARK
LAKELAND
LAKELAND
EATON PARK
EATON PARK
EATON PARK

-------
                      A1K PUMP  AND  TRACK  ETCH  AVERAGES AND ALL LOCATION DATA




LLCATION  AP_MEAN   TE_MEAN   GF_GAMMA   OUT_GAMA  USE  CLASS  TYPE  LEVELS  MATRIAL  A_C
          15
CITYNAME
70736
70737
7C738
70739
7C74G
70741
7C742
70743
70744
7G74b
7G746
70747
70748
70749
70750
70751
70752
70753
70754
70755
70756
70757
70758
70759
70760
70761
70762
70763
70764
70765
70766
70767
70768
70769



0,0072
0.0255





C.0047




0.0395














0.0127



6
7
6
13
9
6
7
12
7
8
7
8
21
6
6
7
10
6
5
6
12
7
6
7
7
8
8
8
8
8
11
7
7
7
7
7
7
25
16
8
13
20
14
14
14
7
23
9
7
9
12
6
6
6
13
10
10
1C
12
11
1C
8
11
10
2C
9
1C
10
R
R
R
R
R
R
R
R
R
R
K
R
R
R
R
R
R
U
U
U
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
4
2
2
2
3
2
2
2
4
2
2
2
2
4
2
2
2
2
2
2
2
2
1
1
1


1
1
1
1
1

1
I
1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1

1
1
I
1
I
1


1
1
1
1
1

1
2
1
1

1
1
1
1
2
1
1
1
1
1
1
1
1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
EATON PARK
EATON PARK
EATON PARK
LAKELAND
LAKELAND
EATON PARK
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
EATON PARK
LAKELAND
EATON PARK
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
MULBERRY
MULBERRY
MULBERRY
MULBERRY

-------
                      AIR PUrtP  AND  TRACK ETCH AVERAGES AND ALL LOCATION  DATA




LCCATION  AP_MEAN  TE_M£AN  GF_GAM,MA  CUT_GAMA  USE   CLASS  TYPE  LEVELS  MATRIAL  A_C   CITYNArtE
17
7C770
70771
7C772
7C773
70774
7C775
7C776
7C777
7C778
7C779
7C780
7C781
7C782
7C783
7C784
70785
7C786
7C787
7C788
7C789
7C79G
7C791
7C792
7C793
7C794
7C795
7C796
7C797
7C798
7C799
70800
7C80L
7G802
7C803








0.0071


0.0032




0.0094



C.0326

0.0042
0.0040


0.0096
C.0139

G.0343


0.0110
C.0072
10
a
7
9
8
5
5
7
6
10
6
7
8
11
9
8
8
7
10
Q
7
7
11
8
19
7
9
10
7
7
8
10
11
17
9
8
8
10
10
5
5
7
7
19
11
12
10
8
8
10
8
9
14
12
9
11
14
9
22
11
14
3C
9
17
11
14
20
24
R
R
R
R
R
N
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1'
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
4
4
4
4
4
4
4
4
4
2
2
2
3
2
2
2
2
2
2
2
2
2
2
2
3
2
2
2
2
2
3
2
2
3
1
1
1
1
1
1
1
1

1
1

1
1
I
1

1
1
1

1


2
1


1

1
1


2
2
2
2
2
2
2
2

1
1

1
1
1
1

1
1
1

1


2
1


1

2
1


1
1
1
1
1
1
1
1
2
1
1
I
1
1
1
2
2
2
1
2
2
2
1
2
2
1
1
1
1
1
2
2
1
1
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MUL6ERHY

-------
                      AIR  PUMP  ANJ TRACK ETCH AVERAGES  ANC  flLL  LUCATIGN  OATA
                                                                                 18
LCCATICN  AP_MEAN
TE_MEAN  GF_GAMMA  CUT_GAMA   USE   CLASS  TYPE  LfcVhLS  MATRIAL   A_C  CITYNAME
7C8U4
7C805
7C806
70807
7C808
7C809
7C810
7C811
7C813
7C814
7C815
7C816
7C817
7C818
7CB19
7C820
7C821
70822
7C823
7C824
7C825
70826
7C827
7C828
7C829
70831
7C832
7C833
7C834
70835
7C836
7C837
7C836
7C839
C.0057

C.0098








0.0100






0.0034

C.0114
0.0100
0.0495



C.0034







7
12
9
7
19
7
7
9
14
12
9
7
6
6
6
5
5
5
13
11
9
23
9
a
8
11
10
16
11
9
7
5
7
8
7
14
8
7
34
11
8
10
16
14
8
10
7
7
7
5
5
5
6
13
11
14
28
8
10
12
9
21
21
20
10
6
7
9
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
ft
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
4
2
2
2
2
3
4
4
4
2
2
2
2
4
4
4
4
4
4
3
3
3
3
3
3
3
4
2
2
2
4
4
4

1

1
1
1
1
1
1
1
1

1
1
1
1
1
1

1



1
1
I

1
1
1
1
1
1
1

2

1
1
1
2
2
2
2
1

1
1
1
2
2
2

2



2
2
2

2
1
1
1
2
2
2
1
1
2
2
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
2
2
2
2
2
1
2
2
2
1
2
1
MULBERRY
MULBERRY
MULBERRY
MULPERKY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
LAKELAND
LAKELAND
LAKELAND

-------
                      AIR PUMP AND TRACK  ETCH AVERAGES ANC  ALL  LOCATION DATA
19
LOCATION  AP_MEAN  TE_MEAN  GF_GAMMA   CLT_GAMA  USE  CLASS  TYPE   LEVELS  MATRIAL  A_C   CITYNAME

 7C840
 7C841
 7C842
 7C843
 7C644
 708*5
 7C£46
 7C847
 7C848
 76850
 7C851
 7C852
 7C853
 7C854    u.0113
 7C655
 7C856
 7C837
 7C858
 7C£59
 7C860
 7C861
 7C662
 7C863
 7CE64
 70865
 7C866
 7C667
 7C868
 7C869
 7CS70
 7C871
 7C872
 7C873    C.OQ57
 7CS74
7
8
3
7
9
10
7
8
7
7
6
7
10
12
8
8
7
7
8
7
8
9
8
7
9
7
7
6
8
6
6
8
7
10
8
S
8
8
9
12
9
S
9
8
8
8
16
15
12
13
8
12
11
11
11
14
16

15
11
8
6
9
7
6
10
7
11
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
1
1
1
1
1
3
3
3
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
4
4
4
4
2
3
4
2
2
2
2
2
2
4
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
i
1
I
1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1

1
2
2
2
2
1
2
2
I
1
1
1
1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1

1
1
1
1
1
1
2
1
1
1
1
1
1
2
I
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
2
1
2
1
LAKELAND
LAKELAND
LAKELAND
LAKELAND
MULBERRY
MULBERRY
FT WEAOE
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
FT MEADE
FT MEADE
FT MEAOE
MULBERRY
FULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND

-------
                      AlK  PUMP  AND TRACK ETCH AVERAGES  AND  ALL  LOCATION DATA
20
LLCATItlSi  AP_MEAN   Tt_MEAN   GF_GAMMA  CLT_GAMA  USE  CLASS   TYPE   LEVELS  MATRIAL  A_C   CITYNAME
7C875
7CE76
7C877
7C878
7C879
71880
7C801
7C882
7C833
7C884
7C8S5
7C836
7C887
7C888
7C88S
7C890
7C891
7C892
7C893
7C894
7C895
7C896
7C897
7C898
7C899
7C900
70901
7C902
7C903
70904
70905
7C906
7C907
7C9C8


0.0143




C.0064









0.0075
C.0051

0.0054





0.0341







6
8
11
7
6
8
8
9
6
7
10
7
7
6
7
6
5
a
12
9
23
13
15
a
9
9
Q
8
7
9
19
14
19
18
7
9
15
11
9
10
13
17
8
10
11
11
9
7
8
7
6
11
18
11
24
14
19
10
10
12
10
12
10
10
23
17
31
27
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
4
3
3
4
4
2
2
2
2
2
3
3
3
4
4
4
1
1

1
1
1
1

1
1
1
1
1
1
1
1
1


1

1
1
1
1
1

1
1
1
1
1
1
1
1
1

1
I
1
1

1
1
1
1
1
1
1
1
1


2

2
2
1
1
1

1
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
1
1
2
1
1
1
1
2
1
1
2
2
2
1
1
1
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
LAKELAND
LAKELAND
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
MULBERRY

-------
                     AIR  PUMP  AND TRACK ETCH AVERAGES AND  ALL  LOCATION  DATA

LOCATION  AP_MEAN   TE_MfcAN   GF_GAMMA   CUT_GAMA  USE  CLASS  TYPE   LEVELS  NATRIAL
                                                                                           21
                                                                           A_C  CITYNAME
 7C909
 7C910
 7G9L1
 7C912
 7C913
 7C9i4
 7C915
 7C916
 70917
 7C918
 7C919
 7C920
 70921
 7C922
 70923
 70924
 70925
 70926
 70927
 7C928
 7C929
 7C930
 7C931
 7C932
 7C933
 70934
 7C935
 70936
 7C937
 70938
 7C939
 70940
 70941
 7G942
0.0069
0.0148
0.0373
0.0513
0.0261
C.0305
0.0075
C.0098
13
11
 8
 7
 7
 7
 7
 7
 7
10
 7
 8
 o
11
11
10
10
10
 8
11
10
 8
 9
 9
 8
 7
 8
 8
 8
 7
 3
10
 7
 6
15
13
11
10
10
9
9
10
8
1U
10
9
10
21
18
17
19
14
10
14
18
0
10
10
10
10
10
10
9
10
12
15
8
8
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
1
1
1
3
3
3
3
5
1
1
1
1
1
1
1
1
1
1
1
1
1
3
3
3
3
3
1
1
1
1
1
1
1
1
4
2
3
2
1
2
2
2
3
2
2
2
2
2
2
2
2
3
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1






2
1
1
1
1
L
1
1
1
1
1
2
1
1
2
1
1
1
1
1

1
1
1
1

2
1






2
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1

1
1
1
1

1
1
1
1
1
1
1
1
2
2
1
1
1
2
2
2
2
2
2
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
MULBERRY
MULBERRY
BARTOW
BARTOW
BAR TOW
BARTOW
BARTOW
BARTOW
BARTOW
BARTOW
BARTOH
FT MEAOE
BARTOW
FT MEAOE
BARTOW
FT MEADE
FT MEAOE
BARTOW
FT MEAOE
FT MEADE
FT MEADE
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
MULBERRY
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND

-------
                       AIR PUMP AND TRACK ETCH AVERAGES  ANC ALL LOCATION DATA                        22

LCCATION  AP_MEAN   T£_MEAN  Gh_GAMMA  JIT_GAMA   USE   CLASS  TYPE  LEVELS  MATRIAL   A_C  CITYNAME

 7C943
 70944
 7C945
 70946    C.OC84
 7C947
 70948
 70949
 70950
 70951
 70952    0.0351
 70953
 7G954
 70955
 70956
 70957
 7C958    C.0179
 70959
 7C960
 70961
 7C962
 7C963
 7C964
 70965
 7C966
 7C967
 70968
 70969
 70970
 7C971
 70972
 7C973
 70974
 7C975
 7G976
7
9
20
16
21
15
18
9
6
22
11
9
12
8
11
10
7
6
7
6
7
7
6
6
6
6
6
8
6
6
5
6
5
5
8
10
22
16
24
17
19
14
9
20
15
13
15
10
14
17
7
6
6
6
6
7
6
6
6
6
6
8
6
6
5
5
5
5
U
U
R
R
R
R
R
U
R
R
R
R
R
U
U
U
U
U
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
4
4
4
4
4
4
4
2
2
4
2
2
3
2
4
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
1

1
1
1
1
1

1
1
1
1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
2
2
2

2
2
2
1
1

1
1
2
1
2

I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
2
1
1
1
2
1
1
2
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
LAKELAND
LAKELAND
EATON PARK
EATON PARK
LAKELAND
LAKELAND
LAKELAND
LAKELAND
EATON PARK
EATON PARK
LAKELAND
MULBERRY
MULBERRY
LAKELAND
MULBERRY
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
MULBERRY
LAKELAND
MULBERRY
MULBERRY
MULBERRY
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND

-------
                       AIR PUMF ANO  TRACK ETCH AVERAGES  ANC  £LL LOCATION DATA
23
LCCATIUN   AP_MEA,M  TE_MEAi4  GF_GAMMA  UtT_GAMA  USE  CLASS   TYPE  LEVELS  MATRIAL   A_C  CITYNAME

 7C977
 7CS78
 7CS79
 70S 80
 70S 81
 7C982
 7GS83
 7CS84
 7CS85
 70S86     0.0029
 70S67
 7CS88
 7CS89
 7C99Q
 7C991
 70992
 7C993
 7C994
 7C99t>
 7C996
 7C9S7
 7C988
 7C999
 71000
 71001
 71CC2
 71003
 710C4
 71005
 710C6
 71007
 710C8
 71CC9
 71010
6
5
7
7
7
5
12
11
10
6
5
5
5,
5
5
7
5
5
8
5
5
7
5
5
6
6
6
6
6
6
6
6
6
5
5
5
11
9
7
6
<;
10
10
6
5
5
5
6
5
7
5
5
6
5
6
7
5
5
6
6
7
6
6
6
6
6
6
6
N
N
U
U
U
U
U
J
U
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
i.
2
2
4
2
2
2
2
3
2
2
2
2
2
2
2
2
2
3
2
2
3
2
2
2
2
2
2
2
2
2
3
1
1
1
1
L
1
1
1
1

1
I
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1
2
L
1
1

2
1
1
1
1
1
1
1
1
2
2
1
I
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
2
2
2
1
1
1
1
2
1
2
1
2
2
2
1
1
1
1
1
1
1
1
1
1
LAKELAND
LAKELAND
BARTCW
HARTDW
BARTGW
PIERCE
BARTLW
6ARTOW
BARTON
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPGKT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
LAKELAND
MULBERHY
MULBCRftY
MULBERRY
MULBERRY
MULBERRY
MULBERRY
POLK CITY
POLK CITY
POLK CITY

-------
                        AIR  PUMP  AND TRACK ETCH  AVERAGES ANC  ALL  LOCATION DATA
24
LOCATION  AP_MEAN  TE_ME/>N   GF_GAMMA  GUT_GAMA   USfc  CLASS  TYPE   LEVELS  MATRIAL   A_C  CITYNAME
71011
71012
71013
71014
71015
71016
71017
71C18
71019
71020
71021
71022
71023
71024
71025
71026
71027
71028
71C29
71030
71031
71032
71033
71034
710-5
71036
71037
71C38
71039
71040
71041
71042
71043
71044


0.0038





0.0024



O.C041










0.0025
O.C011
O.C045








                                 7
                                 6
                                 6
                                 5
                                 5
                                 6
                                 6
                                 7
                                 7
                                 6
                                 6
                                 5
                                 5
                                 5
                                 6
                                 b
                                 5
                                 5
                                 5
                                 b
                                 5
                                 5
                                 6
                                 6
                                 6
                                 6
                                 5
                                 5
                                 5
                                 5
                                 5
                                 3
                                 5
                                 5
8
7
6
6
6
6
7
8
7
6
6
5
5
5
6
6
6
5
5
5
5
5
6
6
6
5
6
5
5
5
5
5
5
5
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
1
1
1
1
1
1
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
i
1
3
3
3
1
3
1
2
2
2
2
2
2
2
1
2
2
2
2
2
2
2
2
2
2
3
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
1
1

1
1
1
1
1

1
1
1

1
1
1
1
1
1
1
1
I
1



1
1
1
1
1
1
1
1
1
1

1
1
1
1
1

1
1
1

1
1
1
1
1
2
1
1
1
I



1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
2
1
2
2
2
2
1
1
1
2
2
1
1
2
1
2
2
2
2
1
1
1
1
1
1
1
POLK CITY
POLK CITY
POLK CITY
POLK CITY
POLK CITY
POLK CITY
POLK CITY
POLK CITY
POLK CITY
POLK CITY
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
DAVENPORT
hAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES C[TY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY

-------
                        AIR PUMP ANO TRACK  ETCH AVERAGES AND  ALL  LOCATION DATA

LOCATION  AP_HFAN  T E_MEAN  GF_GAMMA  GUT_GAMA  USE  CLASS   IYPE  LEVELS  MATRIAL

                                5
                                5
                                5
                                5
                                5
                                5
                                7
                                5
                                5
                                5
                                6
                                6
                                5
                                6
                                5
                                5
                                5
                                5
                                5
                                5
                                5
                                5
                                6
                                8
                                5
                                5
                                5
                                5
                                5
                                5
                                5
                  25
A_C
C1TYNAHE
71045
71046
71047
71048
71049
71050
71051
71052
71053
71054
71055
71056
71057
71058
71059
7106C
71061
71062
71G63
71064
71065
71066
71067
71068
71069
71070
71071
71072
71C73
71074
71C75
71C76
71C77
71078


0.0028






O.C025



O.C030
0.0033



0.0022
0.0118

O.C027












5
5
5
5
5
5
6
5
6
6
5
6
6
7
6
5
6
5
5
5
5
5
5
5
5
5
10
6
5
5
5
6
5
5
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
3
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
i
1
1
1
2
2
3
2
2
3
2
2
2
2
2
2
2
2
2
2
3
2
3
2
2
2
2
2
2
2
2
2
2
2
2
2
3
2
1
1

1
1
1
1
1
1

1
1
1


1
1
1


1

I
1
1
1
1
1
1
1
1
1
1
1
1
1

1
1
2
1
1
1

1
1
1


1
2
1


1

1
I
1
1
i
I
1
1
1
1
2
1
1
1
1
1
1
1
2
1
1
2
1
1
2
1
1
1
I
1
2
1
1
1
2
1
2
1
2
1
1
1
1
2
1
2
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HA1NFS CITY
HAINtS CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
HAINES CITY
FROSTPROOF
FKGSTPKOGF
FROSTPROOF
FRCSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF

-------
                       AIR HUMP  AND  TRACK ETCH AVERAGES  AND  ALL  LOCATION DATA
26
LCCATION   AP_MEAhi  TE.MEAN  GI-_GAMMA   GIT_GAMA  USE  CLASb   TYPE  LEVELS  MATRIAL  A_C   CITYNAME

 71C79
 71C80
 71081
 71082
 71C33
 7108-*
 71CB5
 71C86
 71C87
 71C8d
 71 CSS)
 71090
 71G91
 71092
 71C93
 71C94
 71U95
 71C96     C.OG41
 71CS7
 71093
 71 C !9'*
 71100
 71101
 711C2
 71103
 71104
 7 1106
 71107
 71103
 711C9
 71110
 71111
 71112
5
5
6
6
7
5
6
6
7
b
5
5
5
5
5
5
5
6
6
5
b
5
6
7
6
5
5
5
5
5
5
Lu
5
b
5
5
5
6
8
5
6
6


6
5
5
6
6
5
5
6
6
5
5
6
7
6
6
6
6
6
5
6
5
12
5
6
N
N
Ni
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
\
N
N
N
N
N
N
N
N
N
N
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
I
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
3
2
2
3
4
4
2
4
2
2
2
2
2
2
2
2
2
1
3
2
3
2
2
3
2
3
2
3
2
I
I
1
2
1
1
I
1
1
1
1
1
1
1
1
1
1

I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
2
2
1
2
1
1
1
1

1
1
1
I
1
2
1
2
1
1
2
L
1
1
2
1
1
1
1
1
I
1
1
2
2
2
2
1
2
I
1
2
1
1
1
1
2
2
2
2
1
2
1
2
2
1
1
1
1
1
FRUSTPHOLF
PCLK CITY
POLK CITY
PCLK CITY
PCLK CITY
PCLK CITY
PCLK CITY
PCLK CITY
PCLK CITY
PCLK CITY
PCLK CITY
PCLK CITY
PCLK CITY
DUNDEE
DUNOFF
DUNDEE
CUNOEE
DUNDEE
DUNDEE
DUNOFE
DUNDEE
DUNDEE
DUNDEE
DUNDEE
DUNDEE
DUNDEE
DUNDEE
CUNDCE
DUNDEE
DUNDEE
DUNDEE
DUNDEE
DUNDEE
DUNDEE

-------
                       A Ik PUMP AND TRACK  ETCH AVERAGES ANC  ALL  LOCATION DATA                        27

LLCATION  AP_MEAi\  TE_MEAN  GF_uAMMA  OUT_GAMA  USE  CLA. S  TYPE   LEVELS  MATRIAL  A_C   CITYNAME
 7111J
 71114
 7111i>
 71116
 71117
 71118
 71119
 71120
 71121
 71122
 71123
 71124
 71125
 71126
 71127
 71123
 71129
 71130
 71131
 71132
 71133
 71134
 71135
 71136
 71137
 71136
 71139
 7114J
 71141
 71142
 71143
 71144
 71145
 71146
0.0024
C.UL81
C.0035
C.0033
5
6
5
6
6
5
5
5
5
5
6
8
6
5
5
5
5
6
5
5
5
5
5
9
5
6
6
5
5
5
6
5
5
s
5
5
5
6
6
5
5
5
5
6
5
6
5
6
5
5
5
6
5
5
5
5
5
7
5
5
5
6
6
5
5
5
5
N
\
N
IM
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
1
1
3
3
3
3
3
3
3
3
3
3
5
3
1
1
I
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
3
2
2
2
2
2
2
2
2
2
2
2
2
3
3
3
3
4
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2

1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
I
2
1
1
1

1
1
1

1
1
1

1
1

1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
1
1
1
1
1
1
1

1
1
1

1
1
1
2
2
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
2
1
1
2
2
DUNDEE
DUNDEE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
LAKE
WALES
WALES
WALES
WALES
WALES
WALES
HALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES
WALES

-------
                       AIR FJMP AND TRACK ETCH AVERAGES  AND  ALL  LOCATION  DATA
                                                                                           28
LCCATIGN  AP_MbAN  TE_ME«I  GF_GAMMA  UUT.GAMA  USE  CLASS   TYPE   LEVELS   MATRIAL  A_C  CITYNAME
 71147
 71148
 71149
 71150
 71151
 71152
 71153
 71154
 71155
 71156
 71157
 71158
 71159
 71160
 7U61
 71162
 71163
 71164
 71165
 71166
 71167
 71168
 71169
 71170
 711,1
 71172
 71173
 71174
 71175
 71176
 71177
 71178
 71179
 71180
0.0018
5
5
6
6
6
5
5
5
t>
5
5
5
5
5
5
5
5
5
5
5
7
5
5
6
5
5
10
10
10
9
7
5
9
10
5
5
6
6
6
5
5
5
5
5
5
5
5
6
5
5
5
5
5
5
6
5
5
7
5
5
11
10
13
1C
9
5
1C
11
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
L
1
1
I
1
1
2

I
1
1
2
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
1
2
2
2
1
2
2
1
1
1
2
2
2
2
2
1
1
2
1
2
2
1
LAKE WALES
LAKE KALES
BARTON
BARTGfe
BARTCW
8ARTGW
BARTOW
BARTOW
BARTGfc
BARTGW
BARTOW
BARTON
BARTOW
BARTOW
BARTOh
BARTOW
BARTOte
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
FROSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF
BARTOW
FROSTPROOF
FROSTPROOF
FROSTPROOF

-------
                       AIR PUMP AND TRACK  ETCH AVERAGES AND  ALL  LOCATION DATA                        29

LCCATIGN  AP_MEA.\  TE.MEAU  GF_GAMMA  OUT_GAMA  USE  CLASS   TYPE   LEVELS  MATRIAL   A_C    CITYNAME

 71181
 71182
 71183
 711S4
 71185
 711 80
 71187
 71188
 71189
 71191
 71192
 71193
 71194
 711S5
 71196    G.0224
 71197
 71198
 71199
 71200
 71201
 71202
 71203
 71204
 71205
 71206    C.0204
 71207
 712C8
 71209
 71210
 71211
 71212
 71213
 71214
 71215
5
5
5
9
10
10
11
11
8
7
8
10
10
9
9
7
7
7
6
7
6
7
6
6
6
6
0
6
6
6
6
9
a
6
5
5
5
S
11
11
11
12
9
9
9
10
1C
10
8
7
8
7
6
7
7
7
7
7
6
6
6
6
6
7
6
a
8
6
N
N
N
N
N
N
N
N
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
N
M
M
M
M
M
M
H
M
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
3
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
2
2
I
1
1
1
1
1
1
1
1
1
1
1
1
1

1
1
1
1
1
1
1
1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1

I
1
1
1
1
1
1
1
1

1
1
1
1
1
1
1
1
1
1
1
2
1
1
2
2
2
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
FROSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF
FROSTPROOF
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND

-------
                       AIR PUrtP AND  TRACK  ETCH  AVERAGES  *ND 4LL LOCATION DATA
            33
LOCATION  AP_MEAN  TE_MEAN   Gf_«AMMA  OUT_GAMA   USE   CLASS  TYPE  LEVELS  MATRIAL  A_C  CITYNAME
 71216
 71217
 71218
 71219
 71220
 71221
 71222
 71223
 71224
 71225
 71226
 71227
 71228
 71229
 71230
 71231
 71232
 71233
 71234
 71235
 71236
 71237
 71238
 71239
 712-iO
 71241
 71242
 71243
 71244
 71245
 71246
 71247
 71248
 71249
6
6
8
8
11
6
6
7
7
7
8
6
7
6
6
7
7
9
6
8
6
6
6
6
6
6
8
6
7
7
6
8
6
5
7
6
7
6
6
7
7
8
7
8
7
6
8
6
5
8
7
8
6
7
6
6
7
7
6
6
9
6
7
7
7
6
6
5
M
M
M
M
M
M
M
M
M
M
M
N
M
M
M
M
M
M
M
M
M
M
M
M
N
N
N
N
N
N
N
N
N
N
1
1
1
1
1
1
1
1
1
1
1
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
2
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
2
2
2
2
2
2
2
2
LAKELAND
LAKELANO
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELANO
LAKELAND
LAKELAND
LAKELANO
LAKELAND
LAKELAND
LAKELAND
LAKELANO
LAKELAND
LAKELAND
LAKELAND
LAKELANO
LAKELAND
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN

-------
                        Alk PUMH AuU TRACK  cTCH  AVERAGES 4.\ C ALL LGCATIGN  DATA
31
LGCATILN  AP_MEAN  TE_MfcAN  GP_oAM>4A  UUT_GAfA   USE  CLASS   TYPE  LEVELS  MATKlAL  A_C     CITYNAML

 7 12 50
 71251
 71252
 71253
 71254
 71255
 71256
 71257
 71258
 71259
 71260
 71261
 712b2
 71263
 71264
 71265
 71266    O.CObO
 71267
 71268
 71269
 71270
 71271    O.C056
 71272
 71273
 71274
 71275
 71276
 71277
 71278
 7127S
 71280
 71281
 71282
 71283
5
5
6
5
5
5
6
b
6
5
7
f>
5
5
5
5
6
5
6
6
5
4
5
5
5
5
5
5
5
23
5
5
5
5
5
5
6
5
6
6
7
5
6
5
6
c
K
5
5
6
8
5
5
5
5
5
5
5
c
-*
5
C
^f
5
c
-^
5
5
5
5
5
N
(Si
N
K
N
N
N
f.
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
iNi
N
N
N
N
N
N
N
N
N
N
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
1

1
I
1
1

1
I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
1
1

1
1
1
1

1
i
1
1
1
1
I
1
1
I
1
1
1
1
2
2
2
2
1
i
1
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
WIMFR
WlMfcR
WIMEH
hIMEk
VvIMEfc
fclNTEk
WlKTtH
WINTER
WIMFK
to I N T E K
wINTEK
BAfcTUw
BAR TO,
BARTOfc
BARTOk
BARTC*
BARTCw
WINTER
WINTEK
WINTER
wINTEK
WINTEK
bINTEK
WINTER
vilisTEH
WINTER
hINTEK
WINTER
WINTER
WINTER
WINTEK
WINTER
WINTER
WINTER
HAVEN
HAVEN
HAVEN
HAVLN
HAVEN
HAVtN
HAVEN
HAVfcN
HAVEN
HAVEN
HAVEN






HAVEN
HAVEN
HAVEN
HAVEN
HAVEN
HAVEN
HAVEN
HAVEN
HAVEN
HAVEN
HAVEN
HAVEN
HAVEN
HAVEN
HAVEN
HAVEN
HAVEN

-------
                        AlK PUMP AND TKACK ETCh AVERAGES  AND  ALL LOCATION DATA

LCCATlLiM  AP_i-lEAiN4   TE_ME/»N  GF_GAMMA  GJT_GAMA  USE  CLASS   TYPE  LEVELS  MATRIAL
                                                                           A_C
 712E5
 712S6
 7128 1
 71288
 71290
 71291
 71292
 71293
 71294
 71295
 71296
 71297
 71298
 71299
 71300
 71360
 71361
 71362
 71363
 71364
 71365
 71366
 71368
 71369
 71370
 71371
 71372
 71373
 71374
 71375
 71376
 71377
 71378
0.0043
O.C070
5
to
9
fa
9
7
7
8
6
6
6
7
9
7
8
7
5
to
6
6
6
6
6
5
5
5
5
5
5
to
6
6
c
5
6
7
e
7
7
6
6
7
6
6
6
e
7
7
8
6
6
6
6
6
6
£
5
5
5
5
5
5
6
6
6

N
N
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
R
R
R
P
M
M
M
M
M
M
M
M
M
M
1
1
1
1
1
1
i
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
I
I
1
1
1

1
1
1
1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1

1
1
1
1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
  CITYNAME

WINTER HAVEN
WIMEn HAVEN
LAKEL.AND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
LAKELAND
AUbURNOALE
AUBURNDALE
AU6URNDALE
AUBURNOALE
AUBURNOALE
WINTER HAVEN
HINTS* HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
AUBURNDALE
AUBUKNOALE
AU6URNDALE
AUBURNOALE

-------
                         A Ik PUMP  ANO TRACK  ETCH AVERAGES  ANQ ALL  LOCATION DATA
LOCATION   AP_MtAN   TE_MEAN  GF_GAMMA  GUT_GAMA  USE   CLASS  TYPE   LEVELS   MATRIAL  A_C   CITYNAME
 7137S
 71380
 71331
 71382
 71383
 71384
 71385
 71386
 71387
 71388
 71389
 71390
 7 1391
 71392
 71393
 71394
 71395
 713S6
 71397
O.C029
O.C100
 6
 6
 5
 5
 5
 5
 5
 5
 5
 5
 5
 5
 5
 5
 5
 8
14
16
 7
6
6
6
6
6
5
5
5
5
5
5
5
5
5
5
1C
12
18
7
M
M
M
M
M
M
M
K
M
M
M
M
M
M
M
M
R
R
M
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
I
2
3
2
2
2
2
2
2
2
2
2
2
2
2
2
3
4
4
4
I

I
1
1
1
1
1
1
1
1
1
1
1
1
1
1
L

1

1
1
1
1
1
1
1
I
1
1
1
1
1
2
2
2

1
2
1
I
1
1
1
1
1
1
1
1
1
1
1
2
2
1
1
AUBURNOALE
AUBURNDALE
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
WINTER HAVEN
FT MEAOE
FT MEADE
FT MEAOE
FT MEADE
 OU.S. GOVERNMENT PRINTING OFFICE: 1979 281-147/94 1 -3

-------