United States
           Environmental Protection
           Agency
Air and Radiation
(6604J)
402-R-93-036
September 1993
                              	•	—•	

-8-EPA   EPA's Map of Radon Zones
           KANSAS

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       EPA'S MAP OF RADON ZONES
       .  •"'•   '  .. •  -KANSAS      -
      '  • •' ••' RADON DIVISION -   • ,:..' ,, _-
  OFFICE OF RADIATION AND INDOOR AIR
U.S. ENVIRONMENTAL PROTECTION AGENCY
             SEPTEMBER, 1993

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                             ACKNOWLEDGEMENTS.
       This document was prepared by the U.S. Environmental Protection Agency's (EPA's)
Office of Radiation and Indoor Air (ORIA) in conjunction with the U.S. Geological Survey
(USGS)  Sharon W. White was the EPA project manager. Numerous other people in ORIA
were instrumental in the development of the Map of Radon Zones, including Lisa Ratcliff,
Kirk Maconaughey, R. Thdmas Peake, Dave Rowson,.and Steve Page.

       EPA would especially like to acknowledge the outstanding effort of the USGS
radon team — Linda Gundersen, Randy Schumann, Jim Otton, Doug Owen, Russell
Dubiel, Kendell Dickinson, and Sandra Szarzi -- in developing the technical base for the
Map of Radon Zones.                                                           r

       ORIA  would also like to recognize the efforts of all the EPA Regional Offices in
coordinating the reviews with the  State programs and the Association of American State
Geologists (AASG) for  providing  a liaison  with the State geological surveys. In addition,
appreciation is expressed to all of the State radon programs and geological«sur«eys for their
technical input and review of the Map of Radon Zones.

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           TABLE OF CONTENTS
               I.  OVERVIEW
     II. THE USGS/EPA RADON POTENTIAL
        ASSESSMENTS:INTRODUCTION
  III. REGION 7 GEOLOGIC RADON POTENTIAL
                SUMMARY

V. PRELIMINARY GEOLOGIC RADON POTENTIAL
          ASSESSMENT OF KANSAS
  V. EPA'S MAP OF RADON ZONES - KANSAS

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                                      OVERVIEW
        Sections 307 and 309 of the 1988 Indoor Radon 'Abatement Act (IRAA) direct EPA to
 identify, areas of the United States that have the potential to produce elevated levels of radon.
 EPA, the U.S- Geological Survey (USGS), and the Association of American  State Geologists
 (AASG) have-worked closely over the past several years to produce a series  of maps  anS
 documents which address these directives.  The EPA Map of Radon Zones is a compilation of
 that work and fulfills the requirements of sections 307 and 309 of IRAA. The-Map of Radon
 Zones identifies, on a county-by-county basis, areas of the U.S. that have the highest potential
 for elevated indoor radon levels (greater than 4 pCi/L).
        The Map of Radon Zones is designed to assist national, State and. local  governments
 and organizations to target their radon program activities and resources.  It is also intended to
 help building code officials determine areas that are the highest priority for adopting radon-
• resistant building practices. The Map of Radon Zones should not be used to determine if
 individual homes in any given area need to be tested for radon.   EPA  recommends that all
 homes be tested for radon, regardless of geographic location or the zone designation of
 the county in which they are located.
        This .document provides background information concerning the development of'the
 Map of Radon Zones. It explains the purposes of the map, the approach for  developing the
 map (including the respective roles of EPA and USGS), the data source's^used,  the conclusions.
 and confidence levels developed for the prediction of radon potential, and the review  process
 that was conducted to-finalize this effort,                 ,       .           .  "'"*

 BACKGROUND

        Radon (Rn222) is a colorless, odorless, radioactive gas.  It comes from the natural
 decay of uranium that is found in  nearly all soils. ,It typically moves through the ground to
 the air above  and into homes and other buildings through cracks  and openings  in the
 foundation.  Any home,  school or workplace may have a radon problem, regardless of
 whether it is new or old, well-sealed or drafty, or with or without a basement.  'Nearly one out
 of every 15 homes in  the U.S. is estimated to have elevated annual average levels Of indoor
 radon.    '           '  •   '.         ,  -                    '               """" .   "'"*    ,   ".
        Radon first gained national attention in early 1984, when  extremely high levels of
 indoor radon were found in areas of Pennsylvania, New Jersey, and New York, along the
 Reading Prong-physiographic province. EPA established a Radon Program in 1985 to assist
 States and homeowners, in reducing their risk of lung  cancer from indoor radon.
        Since  1985; EPA and USGS have been'working together to continually  increase our
 understanding of radon sources and the migration' dynamics that cause elevated indoor radon
 levels.  Early  efforts resulted in  the 1987 map entitled "Areas with Potentially High Radon •
 Levels." This map vwas based on limited geologic information'only because few indoor radon
 measurements were available at  the time.  The development of EPA's Map of Radon Zones
 and its technical foundation, USGS! National Geologic Radon Province Map, has been based
 on additional  information from six years of the State/EPA Residential  Radon. Surveys,
 independent State residential surveys, and continued expansion of geologic and geophysical
1 information,,particularly the dath from the  National Uranium Resource Evaluation project
                                           1-1

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Purpose of the »Map of Radon Zones

       EPA's Map of Radon Zones (Figure 1) assigns each of the 3141  counties in the
United States to one of three zones:

              o     Zone 1 counties have a predicted average indoor screening level > than
                    4 pCi/L

              o     Zone 2 counties have a predicted average screening level > 2 pCi/L and
                    < 4 pCi/L

              o     Zone 3 counties have a predicted average screening level < 2 pCi/L

       The Zone designations were determined by assessing five factors  that are known to be
important indicators of radon potential: indoor radon measurements,  geology, aerial
radioactivity, soil parameters, and foundation typesl
       The predictions of average screening levels in each of the Zones is an expression of
ifldoiLpotential in the lowest liveable area of a structure.  This map is unable to estimate
actual exposures to radon.  EPA recommends methods for testing and fixing individual homes
based on an estimate of actual exposure to radon. For more information on testing and fixing
elevated radon levels in homes consult these EPA publications: A Citizen's Guide to Radon,
the Consumer's Guide (o Radon Reduction and the Howe Buyer's and Seller's Guide  to
Radoti,                                                   '                      ,
       EPA believes that States, local governments and other organizations  can achieve
optimal risk reductions by targeting resources and program activities to high radon potential •
areas.  Emphasizing targeted approaches (technical assistance, information and outreach
efforts, promotion of real estate mandates and policies and building codes, etc.) in such areas
addresses the greatest potential risks first.         ,
       EPA also  believes that the use of passive  radon control systems in the construction of
new homes in Zone 1 counties, and the activation of those systems if necessitated by- follow-
up testing, is a cost effective approach to achieving significant radon risk reduction.
       The Map of Radon Zones and its supporting  documentation establish no regulatory
requirements.  Use of this map by State or local  radon programs and building code officials is
voluntary.  The information presented on the Map of Radon Zones and in the supporting
documentation is not applicable to radon in water.

Development of the Map of Radon -Zones                        •               •

       The technical foundation for the Map of Radon Zones is the USGS Geologic  Radon
Province Map. In order to examine the radon potential for the United States, the USGS
began by identifying approximately  360 separate geologic provinces  for the  U.S.  The
provinces are shown on the USGS Geologic Radon Province Map (Figure-2).  Each of the
geologic provinces was evaluated by examining the available data for that area: indoor radon
measurements, geology, aerial radioactivity, soil parameters, and foundation  types. As stated
previously, these  five factors are considered  to, be of basic importance in assessing radon
                                          1-2

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Figure 1
                                              EPA   Map   of  Radon  Zones
                                                                               Zone designation for Puerto Rtco ss tinaef d&v&lopftt<&m.
                                                                                                                                          LEGEND

                                                                                                                                             Zone 1

                                                                                                                                             Zone 2

                                                                                                                                             Zone 3
Guam-   Preliminary Zone designation,    j*^ The purpose of (his. map is lo assist National, State and local organizations to target their resources and to Implement radon-resistant building codes.

                                    This map is not Mended to be used to~determ!ne if a home in a given zone should be tested for radon. Homes with elevated levels of radon have"been found
                                    in oil three zones. All homes should be tested, regardless of "geographic location;,         •         •      •              ,          •   .     .
      IMPORTANT;  Consult fft'e EPA Map of Radon Zones document (EPA.-402-R-S3-07t). before using- this 'map. This 'document contains information on radon potential variations  within counties, -
               . £ft4"dto recommends fool this mop be supptemiWtterf Wlrt any available local data in order to further understand and predict the radon potent/a! of a specific area, .    •

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Figure 2
   GENERALIZED GEOLOGIC RADON POTENTIAL OF THE UNITED STATES
                            by the U.S. Geological Survey
                                             Scale
                                        Continental United States
                                            and Hawaii
                                                  500
                                                                 Geologic Radon
                                                                   Potential
                                                                 (Predicted Average
                                                               Screening Measurement)

                                                                   LOW (< 2 pCI/L)

                                                                   MODERATE/VARIABLE
                                                                   (2-4pCI/L)

                                                                   HIGH (>4pCI/L)
                                            Miles
                                                                           6/93

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potential and some data are available for each of these factors in every geologic province. The
province boundaries do not coincide with political borders (county and state) but define areas
of general radon potential.  The five factors were assigned numerical values, based on an
assessment pf their respective contribution to radon potential, and a confidence-level was
•assigned to each contributing variable.  The approach used by USGS/to .estimate the radon
potential for each  province is  described in Part II of this document.                    ,
       EPA subsequently developed the Map of Raciun  Zones by extrapolating iVom the,
province level to the county level so that  all counties in the  U.S. were  assignee! to "one of
three radon zones.  EPA assigned each  county to a given zone based on its provincial radon
potential. For example, if a county is located within a geologic province that has ajpredicted
average screening level greater than 4 pCi/L, it was assigned to Zone 1". Likewise, counties
located in provinces with predicted average screening levels' > 2 pCi/L and < 4 pCi/L, and
less than 2 pCi/L, were assigned to Zones 2 and 3, respectively.
       If the boundaries of a county fall in more than one geologic province,  the county was
assigned to a zone based on the predicted radon potential of the province in which most of
the area lies.  For example, if three different provinces cross .through a given county,  the
county was assigned to the zone representing the radon  potential of the province containing
most  of the county's land area.  (In this case, it is not technically correct to say that the •
predicted average  screening level applies to the entire county since the county falls-in
multiple  provinces with differing radon  potentials.)                          '        ,
       Figures 3 and 4 demonstrate an  example^ of how EPA extrapolated,tfhe county  zone
designations/for Nebraska from  the USGS geologic province map for the State.  As figure 3 -
shows, USGS has identified 5 geologic  provinces for Nebraska.  Most of the counties are
extrapolated "straight" from their corresponding provinces, but there are counties "partitioned"
by several provinces — for example,  Lincoln County.  .Although Lincoln county falls in
multiple  provinces, it was assigned to Zone 3 because most  of its area falls in the province
with the  lowest  radon  potential.         ,
       It is important to note that  EPA's extrapolation from the province level to the
county level  may mask significant "highs"/and  "lows" within specific counties.  In other.
words, within-county variations in radon, potential are not shown on the Map  of Radon
Zones. EPA recommends that users who may need to address specific withifi-county
variations in radon potential (e.g.» local government officials considering the
implementation of radon-resistant construction codes) consult USGS' -'Geologic Radon
Province Map and the State chapters.provided with  this  map for more detailed
information, as well as any locally available data.

Map Validation  *      .  •        ~   ,     ^               •                 '''•'•'

       The Map of Radon Zones is intended to represent a preliminary assessment of radon
potential for the entire United States.  The factors that are used in this  effort —indoor radon
data,  geology, aerial radioactivity, soils, and foundation  type — are basic indicators for radon
potential. It is important to note, .however, that the map's county zone designations are not  •
"statistically valid" predictions due to the  nature of the data  available for these 5 factors at the
county level. In order to validate the map in light of this lack of statistical confidence, EPA
conducted a number of analyses. These analyses have helped EPA  to identify;the best
situations in which to  apply the  map; and its limitations.
                                           1-5

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Figure 3
                 Geologic  Radon Potential  Provinces  for  Nebraska
         Lincoln County
           Bill
                    Uoitt itt
                               Low
Figure 4
         NEBRASKA  -  EPA  Map  of. Radon  Zones
         Lincoln County

         Zoat 1     Zone 2    Zone 3
                                       1-6

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       One such analysis involved comparing county zone designations to indoor radon
 measurements from the State/EPA Residential Radon Surveys (SRRS).  Screening  averages
 for counties with at least 100 measurements were compared to the counties' predicted radon
 potential as indicated by the Map of Radon Zones.  EPA found that 72% of the county
 screening averages were correctly reflected by the appropriate zone designations on the Map.
 In all other cases, they only differed by 1 zone:                  ,    .
       Another accuracy analysis used the annual average data from the National Residential
 Radon Survey (NRRS).  The NRRS indicated that approximately 6 million homes in the
' United States have annual averages greater than or equal to 4 pCi/L.  By cross checking the
 county location of the approximately 5,700 homes which participated in  the survey, their
 radon measurements, and the zone designations for these counties, EPA found that
.approximately 3.8 million homes of the 5,4 million  homes with radon levels greater than or
 equal to 4 pCi/L will be found in counties designated as Zone 1.  A random sampling of an
.equal number of counties would have only found approximately 1.8 million homes greater
 than 4 pCi/L. In other .words, this analysis indicated that the map approach is three times
 more efficient at identifying high radon areas than random selection of zone designations.
       Together, these analyses show that the approach  EPA used to develop the Map of
 Radon Zones is. a reasonable one.  In addition, the Agency's  confidence is enhanced by results
 of the extensive State review process — the map. generally agrees with the States' knowledge
 of and experience in  their own jurisdictions.  However, the accuracy analyses highlight two
 important points:  the fact that elevated levels will be found  in. Zones 2 and 3, and  that there,
 will be significant numbers'of homes with lower indoor radon levels in all of the Zones. For
 these reasons,  users of the Map of Radon Zones need to supplement the Map with locally
 available data whenever possible.  Although all known "hot spots", i.e., localized areas of
•consistently elevated  levels, are discussed in the State--  .
 specific chapters, accurately defining the boundaries of the "hot spots" on this scale of map is
 not possible at this time.  Also, unknown  "hot spots" do exist.                .,
       The Map of Radon Zones is intended  to be a starting point for characterizing radon
 potential because our knowledge of radon sources and transport is always growing.^ Although
 this effort  represents  the best data available at this time, EPA will continue to study these
 parameters and others such  as house construction,/ventilation features and meteoroBgy factors
 in order to better characterize the presence of radon in U.S .homes, especially in high, risk,
 areas. These efforts will eventually  assist EPA in refining and revising the conclusions of the
 Map of Radon Zones. And although this map is most appropriately used as a targeting tool
 by the aforementioned audiences — the Agency encourages  all residents to test their homes
 for radon, regardless of geographic location or the zone designation  of the county in
 which they live.  Similarly, the Map of Radon Zones should not to be used  in lieu of
 testing during real  estate transactions.

 Review Process                                                 ,            <

       The Map of Radon Zones has undergone extensive review,within EPA and outside the
 Agency.  The Association of American State Geologists (AASG) played  an integral role in
 this review process.   The AASG individual State geologists have reviewed their State-specific
 information, .the USGS Geologic Radon Province Map,  and other materials for their geologic
 content and consistency. /
                                           1-7

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       In addition to each State geologist providing technical comments, the State radon
offices were asked to comment on their respective States' radon potential evaluations.  In
particular, the States were asked to evaluate the data used to assign their counties to specific
zones. EPA and USGS worked with the States to resolve any issues concerning county zone
designations.  In a few cases, States have requested changes in county zone designations.  The
requests  were based on additional  data from the State on geology, indoor radon
measurements, population, etc.  Upon reviewing the data submitted by the States, EPA did
make some changes in zone designations. These  changes, which do not strictly follow the
methodology outlined in  this document, are  discussed in the respective State chapters.
       EPA encourages the  States and counties to conduct further research and data collection
efforts to refine  the Map of Radon Zones. EPA would like to be kept informed of any
changes  the States, counties, or others make to the maps. Updates and revisions will be
handled in a similar fashion to the way the map was developed.  States should notify EPA of
any proposed changes by forwarding the changes  through the Regional EPA offices  that  are
listed in  Part II.  Depending on the amount of new information that is presented, EPA  will
consider  updating this map periodically.  The State radon programs should initiate proper
notification of the appropriate State officials when the Map of Radon Zones  is released and
when revisions or updates are made by the State or EPA.
                                           1-8

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     THE USGS/EPA RADON POTENTIAL ASSESSMENTS: AN INTRODUCTION
    '  '     .      '      .v                '..  b>!       '           ':'    '
                      Linda C.S. Gundersen and R. Randall Schumann    , -s
                                  U.S. Geological Survey
                                           and
    ,                .                 Sharon W. White
                           U.S.  Environmental Protection Agency        .   •          '
                                                                    /            .

 BACKGROUND                          .                 .

     The Indoor Radon Abatement Act of 1988 (15  U.S.C. 2661-2671) directed the U.S.
 Environmental Protection Agency (EPA) to identify areas of the United States, that have the
 potential to produce harmful levels of indoor radon. These  characterizations were to be based.
 on both geological data and on indoor radon levels in homes and other structures. The EPA
 also was. directed to develop model standards'and techniques for new building construction
 that would provide adequate prevention or mitigation of radon entry.  As  part of an
 Irjterageney Agreement between the EPA and the U.S. Geological Suryey (USGS),, the USGS
 has prepared radon potential estimates for the United States. This report ,is ©ne of ten
', booklets that document this effort.  The purpose and intended use of these reports is to help
 identify areas where states can target their radon program resources, to provide guidance in
 selecting the most appropriate building code options for  areas, and to provide'geoMal
 information on  radon and geology for each state for federal, state, and municipal officials
 dealing with radon issues.  These reports are not intended to be used as a substitute for  .
 indoor radon testing, and they cannot and should not be used to estimate or predict the
 indoor radon concentrations of individual homes, building sites, or housing tracts.  Elevated
 levels of indoor radon have been found in "every State, and EPA recommends that all homes •
 be tested for indoor radon,                                    '.•        t., .u
     Booklets detailing the radon  potential assessment for the U.S. have been developed'for
 each State.  USGS geologists are the authors of the geologic radon potential booklets.  Each'
 booklet consists of several components, the first being an overview to the mapping  project
 (Part I), this introduction to the USGS assessment (Part II), including a general discupsix>ri of
 radon (occurrence, transport,, etc.), and details concerning the types of data used.  The  third
 component is a summary chapter outlining the general geology and geologic radon  potential
 of the EPA Region (Part III).  The fourth component is  an  individual chapter for each state
 (Par,t IV).  Each state chapter discusses the state's specific geographic setting, soils,  geologic   .
 setting, geologic "radon potential, indoor radon data, and  a summary outliningvthe radon
 potential rankings of geologic areas in the state'.  A variety  of maps are presented in each
 chapter—geologic, geographic, population, soils, aerial radioactivity, and indoor radon data by
 county. Finally, the booklets contain EPA's map, of radon zones  for each state and  an
 accompanying description (Part V).           '           .
     Because of constraints on the scales of maps presented  in these reports^and because the
 smallest .units used to present the indoor radpp data are counties, some"generalizations have
 been  made in order to estimate  the radon potential of each area.  Variations in  geology, soil
 characteristics,  climatic factors, homeowner lifestyles^ and other factors that influence  radon
 concentrations can be quite large within any particular geologic area, so these reports cannot
 be used to estimate or predict the indoor radon  concentrations of individual hom'es  or housing

                              ,       ..     II-1    Reprinted from USGS Open-File Report 93-292

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tracts. Within any area of a given geologic radon potential ranking, there are likely to be
areas where the radon potential is lower or higher than that assigned to the  area as a whole,
especially in larger areas such  as the large counties in some western states.
    In each state chapter, references to additional reports related to radon are listed for the
state, and the reader is urged to consult these reports for more detailed information.  In most
cases the best sources of information on radon for specific areas are state and local
departments of health, state departments responsible for nuclear safety or environmental
protection, and 0.S. EPA regional offices. More detailed information  on state or local
geology  may be obtained from the state geological  surveys.  Addresses and telephone
numbers of state radon contacts, geological surveys, and EPA regional offices are listed in
Appendix C at the end of this  chapter.

RADON GENERATION AND TRANSPORT IN SOILS ,

    Radon %(3;2Rn) is produced from the radioactive decay of radium ("'Ra), which is, in turn,
a product of the decay of uranium (338TJ) (fig. 1). The half-life of 3MRn,is 3.825 days. Other
isotopes  of radon occur naturally,  but, with the exception of thoron (BORn), which occurs in
concentrations high enough to  be of concern in a few localized areas, they are less important
in terms  of indoor radon risk because of their extremely short half-lives and less common
occurrence. In general, the concentration and mobility of radon in soil are dependent on
several factors, the most important of which  are the soil's radium content and distribution,
porosity, permeability to gas movement, and moisture content.   These  characteristics are, in
turn, determined by the soil's parent-material composition, climate, and the soil's age  or
maturity.  If parent-material  composition, climate, vegetation, age of the soil, and topography  .
are known, the physical and  chemical properties  of a soil in a given area can be predicted.
    As soils form, they develop distinct layers, or horizons, that are cumulatively called the
soil profile. The A horizon is  a surface or near-surface horizon containing a relative
abundance of organic -matter but dominated by mineral matter.  Some  soils contain an E
horizon,  directly below the A horizon, that is generally characterized by loss of clays, iron, or
aluminum, and has a characteristically lighter color than the A horizon.  The B horizon
underlies the A or E horizon.  Important characteristics of B horizons  include accumulation of
clays, iron oxides, calcium carbonate or other soluble salts, and organic matter complexes. ,In
drier environments, a horizon may exist within or below the B horizon that is dominated  by
calcium carbonate, often called caliche or calcrete.  This carbonate-cemented horizon is
designated the K horizon in modern soil classification schemes. The C horizon underlies the
B (or K) and  is a zone of weathered  parent material that does not exhibit characteristics of A
or B horizons; that is, it is generally  not a zone of leaching or accumulation.  In soils formed
in place  from the underlying bedrock, the C  horizon is a zone of unconsolidated, weathered
bedrock overlying the unweathered bedrock.
    The  shape and orientation of soil particles (soil structure) control permeability and affect
water movement in the soil.  Soils with blocky or granular structure have roughly equivalent
permeabilities in the horizontal and vertical directions, and air  and water can infiltrate the soil
relatively easily.  However, in  soils with platy structure, horizontal permeability is much
greater than vertical permeability,  and air and moisture infiltration is generally slow.   Soils
with prismatic or columnar structure  have dominantly vertical permeability..  Platy and
prismatic structures form in soils with high clay  contents.  In soils with shrink-swell  clays, air


                                           .11-2     Reprinted from USGS'Open-tile Report 93-292

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        Lead-214

        27mln- XBlsmuth.214
                               138.4 days
                                                                                           Uranlum-238
                                                                                           .51 billion years
                                                                                           247i000 years
                                                                    "J 80,000 years
                                                           Radlum-226 fa
                                                           1602 years
        STABLE
Figure 1.  The uraniurn-238 deeay series, showing the half-lives of elements and their modes of decay (after Wanty and
Schoen, 1991). a denotes alpha decay, p denotes beta decay.

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and moisture infiltration rates and depth of wetting may be limited when the cracks, in the
surface soil layers swell shut. Clay-rich B horizons, particularly those with massive or pl.aty
structure, can  form a capping layer that impedes the escape of soil gas to the surface
(Schumann and others, 1992).  However, the shrinkage of clays can act  to open or widen
cracks upon drying, thus increasing the soij's permeability to gas flow during drier periods.
       Radon transport in soils occurs by  two processes: (1) diffusion and (2) flow (Tanner,
1964).  Diffusion is the process whereby radon atoms move from areas  of higher
concentration  to areas of lower concentration in response to a concentration gradient.  Flow is
the process by which soil air moves through soil pores in response to differences in pressure
within the soil or between the soil and the atmosphere, carrying the radon atoms along with it:
Diffusion is the dominant radon transport  process in soils of low permeability, whereas flow
tends to dominate in highly permeable soils (Sextro and others, 198.7). 'In low-permeability
soils, much of the radon may decay before it is able to enter a building  because its transport
rate is reduced.  Conversely, highly permeable soils, even those that are relatively low in
radium, such as those derived from some types of glacial deposits, have been associated with
high indoor radon levels in Europe and in the northern United States (Akerblom  and others,
1984; Kunz and others, 1989; Sextro and others, 1987).  In areas of karst topography formed
in carbonate rock (limestone or dolomite)  environments, solution cavities and fissures can
increase soil permeability at depth by providing additional pathways for gas  flow.
    Not all radium  contained in soil grains and grain coatings will result in mobile radon
when the  radium decays. Depending on where the, radium is distributed in the soil, many of
the radon  atoms may remain imbedded in  the soil grain  containing the parent radium atom, or
become imbedded in adjacent soil grains.  The portion of radium that releases radon into the
pores and fractures of rocks and soils is called the emanating fraction.  When a radium atom
decays to  radon, the energy  generated is strong enough to send the radon atom a distance of
about 40 nanometers (1 nm  = 10'* meters), or about 2x10:* inches—this is known as alpha
recoil (Tanner, 1980).  Moisture in the soil lessens the chance of a recoiling  radon  atom
becoming imbedded in an adjacent grain.  Because water is more dense  than air,  a  radon atom
will travel a shorter distance in a water-filled pore than in an air-filled pore,  thus increasing
the likelihood  that the radon atom will remain in the pore space. Intermediate moisture levels
enhance radon emanation but do not significantly affect permeability.  However,  high
moisture levels can significantly decrease the gas permeability of the soil and impede radon
movement through  the soil.
    Concentrations  of radon in soils are generally many times higher than those inside of
buildings, ranging from tens of pCi/L to more than "100,000 pCi/L, but typically in the range
of hundreds to low thousands of pCi/L. Soil-gas radon concentrations can vary in  response to
variations in climate and weather on hourly, daily, or seasonal  time scales.  Schumann and
others (1992) and Rose and others (1988)  recorded order-of-magnitude variations in soil-gas
radon concentrations between seasons in Colorado and Pennsylvania.  The most important
factors appear to be (1) soil moisture conditions, which are controlled in large part by
precipitation; (2) barometric pressure; and (3) temperature.  Washington and Rose (1990)
suggest that temperature-controlled partitioning of radon between water  and gas in  soil  pores
also has a significant influence on  the amount  of mobile radon in  soil gas.
    Homes in  hilly limestone regions of the southern Appalachians were found to have higher
indoor radon concentrations during the summer than in the winter. A suggested  cause for  this
phenomenon involves temperature/pressure-driyen flow of radon-laden air from subsurface


                                          II-4    Reprinted from USOS Open-File Report 93-292

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solution^ cavities in the carbonate rock into houses.  As warm air enters solution cavities that
are higher on the hilislope than the homes,'it cools and 'settles, pushing radon-laden iair-from
lower in the cave or cavity system-in to structures on the hillslope (Gammage and others,
1993).  In contrast, homes built over caves having openings situated .below the level of the
i.ome had higher indoor, radon levels in the winter, caused by cooler outside ai, entering the
cave, driving radon-laden air into cracks and solution cavities in the rock and soil, and
ultimately, into homes (Gammage and others, 1993).                               /     "

RADON ENTRY INTO BUILDINGS

    A driving force (reduced atmospheric pressure in the house relative to-the soil, .producing
a pressure gradient) and entry points must exist for radon to enter a building from the soil.
The negative pressure caused by furnace combustion, ventilation devices, and the stack  effect
(the rising and escape of warm air from the upper floors of the building, causing a
temperature and pressure gradient within the structure) during cold  winter months are
common driving forces.  Cracks and other  penetrations through building foundations, sump
holes, and slab-to-foundation wall joints are common entry points.
    Radon levels in the basement are generally higher than those on the main floor or upper
floors of most structures.  Homes with basements generally provide more entry points for
radon, commonly.have a more pronounced stack effect, and typically have' lower air pressure
relative  to the surrounding soil  than  non-basement homes. The  term "nonbas,ement" applies to
slab-on-^rade or crawl space construction.     *                 ,  •        .   '

METHODS AND  SOURCES OF DATA

   'The assessments'of-radon potential  in the booklets that follow this introduction were
made using five main types of data:  (1) geologic (lithologic); (2) aerial radjometric;  (3) soil
characteristics, including soil moisture, permeability, and drainage characteristics; (4) indoor
radon data; and (5) building architecture .(specifically, whether  homes in each area are built
slab-on-grade or have a basement or crawl  space).  These five factors were evaluated and
integrated to produce estimates of radon potential.   Field measurements of soil-gas-radon or
soil radioactivity were not used except where such data were available in existing, published
reports of local" field studies". Where applicable, such field studies are described in the  ,
individual state chapters. .             .     .                              •

GEOLOGIC DATA     "  ,           '.-.•••.•;••    .               . •

    The types and distribution of lithologic units and other  geologic features in an
assessment area are of primary  importance in determining radon potential. Rock types .that"
are most likely to cause indoor radon problems include carbonaceous black shales, glauconite-
bearing  sandstones, certain kinds of  fluvial sandstones and fluvial sediments, phosphorites,
chalk, karst-producing carbonate rocks,  certain kinds of glacial deposits, bauxite, uranium-rich
granitic rocks, metamorphic rocks of granitic composition', silica-rich-volcanic rocks, many
sheared or faulted rocks, some coals, and certain kinds of contact metamorphosed rocks.
Rock types least likely to cause radon problems include marine quartz sands, non-
carbonaceous shales'and siltstones, certain kinds of clays, silica-poof metamorphic and


     •-"'•'.'     • ;'•              '    II-S   '  . Reprinted from USGS Open-File Report 93-292

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igneous rocks, and basalts. Exceptions exist within these general lithologic groups because of
the occurrence of localized uranium deposits, commonly of the hydrothermal type in
crystalline rocks or the "roll-front" type in sedimentary rocks.  Uranium arid radium are
commonly sited in heavy minerals, iron-oxide coatings on rock and soil grains, and organic
«,.aerials  in soils and sediments.  Less common are . ranium associated with pi: jsphate and
carbonate complexes in rocks and soils, and uranium minerals.
    Although many cases of  elevated  indoor radon levels can be traced to  high radium and
(or) uranium concentrations in parent  rocks, some structural features, most notably faults and
shear zones, have been identified as sites of localized uranium concentrations (Deffeyes and
MacGregor, 1980) and have been associated with some of the highest reported indoor radon
levels (Gundersen, 1991). The two highest known indoor radon occurrences are associated
with sheared fault zones in Boyertown, Pennsylvania (Gundersen and others, 1988a; Smith
and others, 1987), and in Clinton, New Jersey (Henry and others, 1991; Muessig and Bell,
1988).

NURE AERIAL RADIOMETRIC DATA

    Aerial radiometric data are used to quantify the radioactivity of rocks and soils.
Equivalent uranium (eU) data provide an estimate of the surficial concentrations of radon
parent materials (uranium, radium) in  rocks and soils. Equivalent uranium is calculated from
the counts received by a gamma-ray detector from  the 1.76 MeV (mega-electron volts).
emission energy corresponding to bismuth-214 ('"Bi), with the assumption that uranium and,
its decay products are in secular equilibrium.  Equivalent uranium is expressed in  units of
parts  per million  (ppm).  Gamma radioactivity also may be expressed in terms of a radium •
activity; 3 ppm eU corresponds to approximately 1 picocurie per gram (pCi/g) of radium-226.
Although  radon is highly mobile in soil  and its concentration is affected by meteorological
conditions (Kovach, 1945; Klusman and Jaacks, 1987; Schery and others, 1984;  Schumann
and others, 1992), statistical correlations between average soil-gas radon concentrations and
average eU values for a wide variety of soils have  been documented (Gundersen and others,
1988a, 1988b; Schumann and Owen, 1988).  Aerial radiometric data can provide an estimate
of radon source strength  over a region, but the amount of radon that is able to enter a home
from  the soil is dependent on several local factors,  including soil structure, grain size
distribution, moisture content, and permeability, as  well as type of house construction and its
structural  condition.
    The aerial radiometric data used for these characterizations were collected as part of the
Department of Energy National Uranium Resource Evaluation (NURE) program of-the 1970s
and early  1980s.  The purpose of the NURE program was to identify and describe areas in the
United States having potential uranium resources (U.S. Department of Energy, 1976).  The
NURE aerial radiometric data were collected  by aircraft in which a gamma-ray spectrometer
was mounted, flying approximately 122  m (400 ft) above the  ground surface.  The equivalent
uranium maps presented  in the state chapters  were  generated from reprocessed NURE data in
which smoothing, filtering, recalibrating, and matching of adjacent quadrangle data sets were
performed to compensate for  background, altitude,  calibration, and other types of enws and
inconsistencies in the original data set (Duval .and others, 1989).  The data were then gridded
and contoured to  produce maps of eU with a pixel  size corresponding to approximately 2.5 x
2.5 km (1.6 x 1.6 mi).


                                          II-6    Reprinted from USGS Open-File Report 93.-192

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                 FLIGHT LINE  SPACING  OF XUKE AEK!AI SURVEYS
                     2  KU (I  KILE)
                     5  IM (3  MILES)
                     2  * 5 III
                 E3  10  LU (6  U1LES)
                     Si: 10 EK
                     NO  DiTA
Figure 2. Nominal flightline spacings for NURE aerial gamnia-ray surveys coveririg the
contiguous United States (fromDuval and others, 1990). Rectangles represent I°x2° quadrangles.

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    Figure 2 is an index map of NURE 1° x 2° quadrangles showing the flight-line spacing
for each quadrangle.  In general, the more closely spaced the flightlines are, the more area
was covered by the aerial gamma survey, and thus, more detail is available in the data set,
For an altitude of 400 ft above the ground surface and with primary flightline spacing
typically between 3 and 6 miles, less than 10 percent of the ground surface of the United
States was actually measured by the airborne gamma*ray detectors (Duval and others, 1989),
although some areas had better coverage than others due to the differences in  flight-line
spacing between areas (fig. 2),  This suggests that some  localized uranium anomalies may not,
have been detected by the aerial surveys,  but the good correlations of eU patterns with
geologic outcrop patterns indicate that, at relatively small scales (approximately  1:1,000,000
or smaller) the National eU map (Duval and others, 1989) gives reasonably'good estimates of
average surface uranium concentrations and thus can assist in the prediction of radon potential
of rocks and soils, especially when augmented with additional geologic and soil  data.
    The shallow (20-30 cm)  depth of investigation of gamma-ray spectrometers, either
ground-based or airborne (Duval and others, 1971; Durrance, 1986), suggests that gamma-ray
data may  sometimes underestimate the radon-source strength in soils in which some of the
radionuclides in the near-surface soil  layers have been transported downward through the soil
profile.  In such cases the concentration of radioactive minerals in the  A horizon would be
lower than in the B horizon, where such  miner.als are typically concentrated.  The
concentration of radionuclides in the. C horizon and below may be relatively unaffected by
surface  solution processes.  Under these conditions the surface gamma-ray signal may indicate
a lower radon source concentration than actually exists in the deeper soil layers, which are
most likely to affect radon levels in structures with basements.  The redistribution of
radionuclides in soil profiles is dependent on a combination of climatic, geologic, and
geochemical  factors.  There is reason to believe that correlations of eU with actual  soil
radium  and uranium concentrations at a depth relevant to radon entry into structures may be
regionally variable (Duval, 1989; Schumann and Gundersen, 1991).  Given sufficient
understanding of the factors cited above, these regional differences may be~ predictable.

SOIL SURVEY DATA                                                       •

    Soil surveys prepared by the U.S. Soil Conservation Service (SCS) provide data on soil
characteristics,  including soil-cover thickness, grain-size  distribution; permeability, shrink-
swell potential, vegetative cover, generalized groundwater characteristics, and  land use.  The
reports  are available in county formats and State summaries. Thfe county reports typically   •
contain  both generalized and detailed maps of soils in the area.
    Because of time and map-scale constraints, it was impractical to examine  county soil
reports  for each county in the United States, so  more generalized summaries at appropriate
scales were used where available.  For State or regional-scale radon characterizations, soil
maps were compared to geologic maps of the area, and the soil descriptions, shrink-swell
potential, drainage characteristics,  depth to seasonal high water table, permeability, and other
relevant characteristics of each soil group noted. Technical soil terms  used in soil surveys are
generally complex; however, a good summary of .soil engineering terms and the national
distribution of technical soil  types is the  "Soils" sheet of the National Atlas (U.S. Department
of Agriculture, 1987). .
                                           II-8     Reprinted from USGS Open-File Report 9,3-292

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    Soil permeability is commonly expressed in SCS soil surveys in terms of the speed, in
inches per hour (in/hr), at which water soaks into the soil, as measured in a soil percolation
test. Although in/hr are not truly units of permeability, these units are ir\ widespread use and
are referred/to as "permeability" in SCS soil surveys. The permeabilities listed in the SCS
surveys are for water, but they, generally correlate -\vell with gas permeability. Because data
on gas permeability of soils is extremely limited, data on permeability to water is used as a '
substitute except in cases in which excessive soil moisture is known to exist. Water in soil
pores inhibits gas transport, so the amount of radon available-to a home  is effectively reduced
by a high water table.  Areas likely to have high water tables include river valleys,  coastal
areas, and some areas overlain by deposits of glacial origin (for example, loess).
    Soil permeabilities greater than 6.0 in/hr may be considered high, and permeabilities less
than 0.6 in/hr may be considered low in terms of soil-gas transport.  Soils with low
permeability  may generally be considered to have a lower radon potential than more
permeable soils with similar radium concentrations.  Many well-developed soils  contain a
clay-rich B horizon that may impede vertical soil gas transport.  Radon generated below this
horizon cannot readily escape to the surface,  so it would instead tend to  move laterally,
especially under the influence of a negative pressure exerted by a building.         • "*
    Shrink-swell potential is an indicator of the abundance of smectitic (swelling) clays in a
soil. Soils with a high shrink-swell potential may cause  building foundations to crack,
creating pathways for radon entry into the structure.  During dry periods, desiccation cracks in
shrink-swell soils provide additional pathways for soil-gas transport and  effectively* increase
the gas permeability of the soil. Soil permeability data and  soil profile data thus provide "
important information for regional radon assessments.

INDOOR RADON DATA   .         .        .  ,;•      •  '    .      -      _,           •    '

    Two major sources of indoor radon data  were used.  The first and largesV source of data is
from the State/EPA Residential Radon Survey (Ronea-Battista and others, 1988; Dziuban and
others, 1990). Forty-two states completed EPA-sponsored indoor .radon surveys, between 1986
and 1992 (fig. 3).  The State/EPA  Residential Radon Surveys were designed to be
comprehensive and statistically significant at the state level, and were subjected to high levels
of quality assurance and control.  The surveys collected screening indoor radon measurements,
defined as 2-7 day measurements using charcoal canister radon detectors placed in the lowest
livable area of the home.  The target population for the surveys included owner-occupied
single family, defeched housing units (White and others, 1989), although attached structures
such as duplexes, townhouses, or condominiums were included in some of thS surveys if they
met the other criteria and had contact with the ground surface.   Participants were selected
randomly from telephone-directory listings.  In total, approximately 60,000 homes were tested
in the State/EPA surveys.                           •                "    •   •
    The second source of indoor radon data comes from residential surveys that have been
conducted in a specific state or region of the country (e.g. independent state surveys or utility
company  surveys).  Several states, including Delaware, Florida^ Illinois,  New Hampshire, New
Jersey, New  York, Oregon, and Utah, have conducted their own "suryeys of indoor  radon; The
quality and design of a state or other independent survey are discussed and referenced where
the data are used.                                             .             ,
                                           II-9     Reprinted from USGS Open-File Report 93-292

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                                           STATE/EPA RESIDENTIAL RADON
                                        SURVEY SCREENING
                                0
Estimated Percent of Houses with Screening Levels Greater than 4 pCi/L

                                                 20     and >
 The States of nR!-1.,NH,NJ,NY, and IJT
 have conducted their own surveys. OK &
 SO declincd'to participate in the SRKS.
                        These results arc based on 2-7 day screening
                        measurements in the lowest livable levei and should not
                        be used to estimate annual averages or health risks.
Figure 3. Percent of homes tested in the State/EPA Residential Radon Survey with screening indoor radon levels exceeding 4 pCi/L.

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     Data for only those counties with five or more measurements are shown in the indoor   -
 radon maps in the state chapters,  although data for all counties with a, nonzero number of
 measurements are listed in the indoor radon data tables in each state chapter.  In total,  indoor
 radon data from more than 100,000 homes nationwide were used in the compilation of these
 assessments.  Radon data from State or regional indoor radon surveys, public health
 organizations, or other sources are discussed in addition to the primary data sources where
 they are available.  Nearly all of the data used in  these evaluations represent short-term (2-7
 day) screening measurements from the lowest livable  space of the homes, Specific details
 concerning the nature and use of indoor radon data sets other than the State/EPA Residential
 Radon Survey are discussed in the individual State chapters.

 RADON'INDEX AND CONFIDENCE INDEX       .    ,

     Many of the geologic methods used ,to evaluate an area for radon, potential -require
 subjective opinions  based  on the professional judgment and experience of the individual
 geologist.  The evaluations are nevertheless based on established scientific principles that are
 universally applicable to any geographic area or geologic setting. This section describes,the
 methods and conceptual framework used by the U.S. Geological  Survey to evaluate areas for
 radon potential based on the five factors discussed in the previous sections. The scheme is
 divided into two basic  parts, a Radon Index (RI),  used to rank the general radon potential of
 the area,  and the Confidence Index (CI), used to express the level of confidence i»'the    " .  .
 prediction based on the quantity and quality of the data used to make the determination.  This
 scheme works best if the areas to be evaluated are delineated by geologically-based
 boundaries (geologic provinces) rather than political ones (state/county boundaries) in which
 the geology may vary across the area.
     Radon Index.' Table'  1 presents the Radon Index  (RI) matrix. The five factors—indoor
 radon data, geology, aerial radioactivity, soil parameters, and house foundation type—were
 quantitatively ranked (using  a point value of 1, 2, or 3) for their respective contribution to  •
 radon potential in a given area. At least some data for the 5 factors are consistently  available
 for every geologic province.  Because each of these main factors encompass a .wide variety of
 complex  and variable components, the geologists performing the evaluation relied heavily on
 their professional judgment and experience in assigning point values to each category and in
 determining the  overall radon potential ranking.  Background information on these factors is
 discussed in more detail in the preceding sections of this introduction.                       .
     Indoor radon was evaluated using unweighted arithmetic means of the indoor radon data
 for each geologic area to be assessed.  Other expressions of indoor-radon levels in an area •
 also could  have  been used, such as weighted averages or annual  averages, but these types of
 data were not consistently available for the entire United States at the time of this writing, oj
 the schemes were not considered sufficient to provide a means of consistent comparison
 across all areas.  For this  report, charcoal-canister screening measurement data from the
 State/EPA  Residential Radon Surveys and other carefully selected sources were used, as
 described in the preceding section.  To maintain consistency, other indoor radon data sets
 (vendor,  state, or other data) were not considered in scoring the  indoor radon factor of the
 Radon Index if they were riot randomly sampled or could not be statistically combined with
 the primary indoor  radon  data sets.  However, these additional radon data sets can provide  a
• means to further, refine correlations between geologic factors and radon potential* so they are


                                  '••'.,     11-11     Reprinted from USGS Open-File Report 93-292

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TABLE I. RADON INDEX MATRIX, "ppm elJ" indicates parts per million of equivalent
uranium, as indicated by MURE aerial radiometric data. See text discussion for details.

FACTOR
INDOOR RADON (average)
AERIAL RADIOACTIVITY
GEOLOGY*
SOIL PERMEABILITY
ARCHITECTURE TYPE
INCREASING RADON POTENTIAL ^

POINT VALUE
1
<2pCi/L
< 1.5 ppm eU
negative
low
mostly slab
2
2-4pCi/L
1.5 - 2.5 ppm eU
* variable
moderate
mixed
3
>4pCi/L
> 2.5 ppm eU
positive
high
mostly basement
*GEOLOGIC FIELD EVIDENCE (GFE) POINTS: GFE points are assigned in addition to points
   for the "Geology" factor for specific, relevant geologic field stu'dies. See text for details.

   Geologic evidence supporting:   HIGH radon        +2 points
                             MODERATE       +1 point
                             LOW             -2 points
                  No relevant geologic field studies     0 points         .   •
SCORING:
            Radon potential category
                      Point ranee
     Probable average screening
       indoor radon for area
            LOW
            MODERATE/VARIABLE
            HIGH
                      3-8 points
                     9-11 points
                     12-17 points
           < 2 pCi/L
           2 - 4 pCi/L.
           >4pCi/L
                     POSSIBLE RANGE OF POINTS = 3 to 17
TABLE 2.  CONFIDENCE INDEX MATRIX
                                    INCREASING CONFIDENCE
FACTOR
INDOOR RADON DATA
AERIAL RADIOACTIVITY
GEOLOGIC DATA
SOIL PERMEABILITY
POINT VALUE
1
sparse/no data
questionable/no data
questionable
questionable/no data
2
fair coverage/quality
glacial cover
variable
variable
3 ' ,„
good coverage/quality
no glacial cover
proven geol. model
reliable, abundant
SCORING:
LOW CONFIDENCE
MODERATE CONFIDENCE
HIGH CONFIDENCE
 4-6  points
 7-9  points
10 -12 points
                     POSSIBLE RANGE OF POINTS = 4 to 12
                                    BE-12     Reprinted torn USGS Open-File Report 93-292

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 included as supplementary information and are discussed in the individual State chapters.  If
 the average screening indoor radon level for an area was less than 2 pCi/L, the indoor radon
 factor was assigned 1 point, if it was between 2 and 4 pCi/L,,it was scored 2 points, and if
 the average screening indoor radon level for an area was greater than 4 pCi/L, the indoor,
 radon factor was assigned 3 RI points.  -...'•
   , Aerial radioactivity data used in this report are from the equivalent uranium map of the
 conterminous United States compiled from NURE aerial gamma-ray surveys (Duval and
 others, 1989).  These data indicate the gamma  radioactivity from approximately the  upper  30
 cm of rock and soil, expressed in units of ppm equivalent uranium. 'An, approximate average
 value of eU was determined visually for each area and point values assigned based on
 whether the overall eU for the area falls below 1.5 ppm (1 point), between 1.5 .and 2.5 ppm
 (2 points), or greater than 2.5  ppm (3' points).
    The geology factor is complex and actually incorporates many geologic characteristics. In
 the matrix, "positive" and "negative" refer to the presence or absence and distribution of rock
 types known to have high uranium contents and to generate elevated radon in soils, or indoors.
 Examples of "positive" rock types include granites, black shales, phosphatic rocks, and other
 rock types described in the preceding "geologic data" section.  Examples-^ "negative" rock
 types include marine quartz sands and some clays.  The  term  "variable" indicates that the
 geology within the region is variable or that the rock types in the area are known or suspected
 to generate elevated radon in some areas but not in others due to compositional  differences,
 climatic effects, localizeddistribution of uranium, or other factors. Geologic information
 indicates not only how much uranium is present in the rocks and soils but also gives clues for
 predicting general radon emanation and mobility characteristics through additional factors
 such  as structure (notably the presence of faults or shears) and geochemica3! Characteristics
 (for example, a phosphate-rich sandstone will likely contain more uranium than  a"sandstone
 containing little or no phosphate because the phosphate forms chemical complexes with
 uranium),  "Negative", "variable", and "positive" geology were assigned  1, 2, and 3 points,
 respectively.   "'            .•'••'     '        -         .        • .
    In cases where additional reinforcing or contradictory geologic evidence is available,
 Geologic Field Evidence  (GFE) points were added to or subtracted from an area's score
 (Table 1). Relevant geologic field studies are important tp enhancing our understanding of
 how geologic processes affect radon distribution. In some cases, geologic models and
•supporting field data reinforced an already strong (high or-low) score; in others, they provided
 important contradictory data.  GFE points  were applied for geologically-sound evidence that
 supports the prediction .(but which may contradict one or more factors) on the basis of known
 geologic field studies in the area or in areas with geologic and climatic settings similar  .
 enough that they could be applied with full confidence.  For example, 'areas of the Dakotas,
 Minnesota, and Iowa that are covered  with Wisconsia-age glacial deposits exhibit a low aerial
 radiometric signature and score only one RI point in that category. However, data from
 geologic field studies in North Dakota and Minnesota (Schumann and others, 1991) suggest
 that eU is a poor predictor of; geologic radon potential in this area because radionuclides have

 ..  ' •     '       / * -     -...-'        -11-13     Reprinted from USGS Open-File Report 93-292,

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been leached from the upper soil layers but are present and possibly even concentrated in
deeper soil horizons, generating significant soil-gas radon.  This positive supporting field
evidence adds two GFE points to the score, which helps to counteract-the invalid conclusion
suggested by the radiometric data.  No GFE points are awarded if there are no documented
field studies for the area.
     "Soil permeability" refers to several soil characteristics that influence radon concentration
and mobility, including soil type, grain size, structure, soil moisture, drainage, slope, and
permeability.  In the matrix, "low" refers to permeabilities less than about 0.6 in/hr; "high"
corresponds to greater than about 6.0 in/hr, in U.S. Soil Conservation Service (SCS) standard
soil percolation tests.  The SCS data are for water permeability, which generally correlates
well with the gas permeability of the soil except when the'soil moisture content is very high,,
Areas with consistently high water tables were thus considered to have low gas permeability.
"Low, "moderate", and "high" permeability were assigned 1, 2,. and 3  points,  respectively.
    Architecture  type refers to whether homes in the area have  mostly basements (3 points),
mostly slab-on-grade construction (1 point), or a mixture of the two.  Split-level and crawl
space homes fall  into the "mixed" category (2 points).  Architecture information is necessary
to properly interpret the indoor radon data and-produce geologic radon potential categories
that are consistent with screening indoor radon data.
     The overall  RI for an area is calculated by adding the individual RI scores for the 5
factors, plus or minus GFE points,  if any.  The total RI for an area falls in one of three
categories—low,  moderate or variable, or high.  The point ranges for the three categories were
determined by examining the possible  combinations of points for the 5 factors and setting
rules such that  a  majority (3 of 5 factors) would determine the final score for the low and
high categories, with allowances  for possible deviation from an  ideal score by the other two
factors. The moderate/variable category lies between these two ranges.  A  total deviation of 3
points from the "ideal" score" was considered reasonable to allow for natural variability of
factors—if two of the five factors are allowed to vary from the "ideal" for  a category, they
can differ by a minimum of 2 (1 point different each) and a maximum of 4.points (2 points
different each).  With "ideal" scores of 5, 10, and 15 points describing low, moderate, and
high geologic radon potential, respectively, an ideal low score of 5 points plus 3 points for
possible variability allows a maximum of 8 points in the low category.  Similarly, an ideal  ,
high score of 15  points minus 3 points gives a minimum of 12 points for the high category.
Note, however, that if both other factors differ by two points from the "ideal", indicating
considerable variability in the system,  the total point score would lie in the adjacent (i.e.,
moderate/variable) category.
    Confidence Index. Except for architecture type, the same factors were used to establish a
Confidence Index (CI) for the radon potential prediction for each area (Table 2).  Architecture
type was not included in the confidence index because house construction data are readily and
reliably available through surveys taken by agencies and industry groups including the
National Association of Home Builders, U.S.  Department of Housing and Urban
Development, and the Federal Housing Administration; thus  it was not considered necessary

                                          11-14     Reprinted from USGS Open-File Report 93-292

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to question the quality of validity of these data.  The other factors were scored on the basis of
the quality and quantity of the data used to complete the RI  matrix,           •
    Indoor radon data were evaluated based on the distribution and number of data points and
on whether the data were collected by random sampling (State/EPA Residential Radon Survey
or other state survey data) or volunteered vendor daia (likely to be nonrandom.and  biased
toward  population centers arid/or high indoor radon levels).  The. categories listed in the CI
matrix for indoor radon data ("sparse or no data", "fair coverage or quality", and  "good
coverage/quality") indicate the sampling density and statistical robustness of an indoor radon
data set.  Data from the State/EPA Residential Radon Survey and statistically valid  state
surveys were typically assigned 3 Confidence Index points unless the data were poorly
distributed or absent in the area evaluated.
    Aerial radioactivity data are available for all  but a few areas of the continental United
States and for part of Alaska.   An evaluation  of the quality of the radioactivity data was based
on whether there appeared to be  a good correlation  between  the radioactivity and the actual
amount of uranium or radium available to generate mobile radon in the rocks and soils of the
area evaluated.  In general,'the greatest problems with correlations among eU,  geology, and
soil-gas or indoor radon levels were associated with glacial deposits (see the discussion in a
previous section) and typically were assigned a 2-p'oint Confidence Index score.  Correlations
among eU, geology, and radon were generally sound in unglaciated areas and were  usually
assigned 3 CI points.  Again, however, radioactivity data in some unglaciated areas  may have
been assigned fewer than  3  points, and in glaciated areas may be assigned only one point,, if
the data were.considered questionable or if coverage was poor.
    To  assign Confidence Index scores for the geologic data factor, rock types and geologic
settings for which a physical-chemical, process-based understanding of radon generation and
mobility exists were regarded as  having "proven  geologic models" (3 points); a high
confidence could be held  for predictions in such  areas. Rocks for which the processes are
less well known or for which data are contradictory were regarded as  "variable"  (2 points),
and those about which little is  known or for which no apparent correlations have been found
were deemed "questionable" (1 point).          '
    The soil  permeability factor was also scored  based on  quality and amount  of data.  The
three categories  fpr soil permeability in the Confidence Index are similar in concept, and
scored similarly, to those  for the geologic  data factor. • Soil permeability can be roughly
estimated from grain size and drainage class if data from standard, accepted soil percolation
tests are unavailable; however,- the reliability of the data would be lower than  if percolation
test figures or other measured permeability data are available, because ah estimate of this type
does not encompass all the factors that affect soil permeability and thus may be inaccurate in
some instances.  Most published soil permeability data are for water; although this is
generally elosely related to  the air permeability of the soil, there are some instances when it
may provide an incorrect estimate.  Examples of areas in which water permeability data may
npt accurately reflect air permeability  include areas with consistently high levels of soil
moisture, or  clay-rich soils, which would have a low water permeability but may have a

             ,                '              11-15     Reprinted from USGS Open-File Report 93-292

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significantly higher air permeability when dry due to shrinkage cracks in the soil.  These
additional factors were applied to the soil permeability factor when assigning the RI score, but
may have less certainty in some cases and thus  would be assigned a lower CI score.
    The Radon Index and Confidence Index give a general indication of the relative
contributions of the interrelated geologic factors influencing radon generation and transport in
rocks and soils,  and thus, of the potential for elevated indoor radon levels to occur in a
particular area.  However,, because these reports are somewhat generalized to cover relatively
large areas of States, it is highly  recommended  that more detailed studies be performed in
local areas of interest, using the methods and general information in these booklets as a-guide.
                                           11-16     Reprinted from USGS Open-File Report 93-292

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                                 REFERENCES CUED

Akerblom, G., Anderson, P., and Clavensjo, B., 1984, Soil gas radon—A source for indoor radon
       daughters: Radiation Protection Dosimetry, v  7, p. 49^54.

Deffeyes, K.S., and MacGregor, IS)., 1980, World uranium resources: Scientific American,
    -  v.242, p. 66-76.                                             ...

Durrance, E.M., 1986, Radioactivity in geology: Principles and applications: New York, N.Y.,
       Wiley and Sons, 441 p.

Duval, J.-S., 1989, Radioactivity and some of its applications in geology: Proceedings of the
       symposium on the application of geophysics to engineering and environmental problems
       (SAGEEP), Golden, Colorado, March 13-16,1989:  Society-of Engineering and Mineral
       Exploration Geophysicists, p. 1-61.

Duval, J.S., Cook, E.G., and Adams, J.A.S., 1971, Circle of investigation of an airborne
       gamma-ray spectrometer: Journal of Geophysical Research, v. 76, p. 8466-8470.
   >         -             '   "  .,                 .'-"'''         ,''
•            •     '            ''..•'.           <   •,       -
Duval, J.S., Jones, W.J., Riggle, F.R., and Pitkin, J.A., 1989, Equivalentinanium map of
       conterminous,United States:  U.S. Geological Survey Open-File Report 89-478,10 p.

Duval, J.S., Reimer, G.M., Schumann, R.R., Owen,,D,E., and Otton, J.K., 1990, Soil-gas
       radon compared to aerial and ground gamma-ray measurements at study sites near Greeley
       and Fort Collins, Colorado:  U.S. Geological Survey Open-File Report 90-648,42 p.

Dziuban, J.A., Clifford, M.A., White, S.B., Bergstein,  J.W., and Alexander, B.V., 1990,
       Residential radon survey of twenty-three States, in Proceedings of the 1990 International
       Symposium oh Radon and Radon Reduction Technology, Vol. HI: Preprints: U.S.     :
       Environmental Protection Agency report EPA/600/9-90/005C, Paper IV-2," 17 p.

Gammage, R.B., Wilson, D.L., Saultz, R.J., and Bauer, B.C., 1993, Subterranean transport of/
       radon and elevated indoor radon in hilly karst terranes:  Atmospheric Environment
       (in press).                              •            •

Gundersen, L.C.S., Reimer, G.M.,  and Agard, S.S., I988a, Correlation between geology, radon
       in soil gas,,and indoor radon in the Reading Prong, in Marikos, M.A., and Hansman, .
       R.BL, eds., Geologic causes of natural radionuclide anomalies: Missouri Department of
       Natural Resources Special Publication 4, p. 91-102.

Gundersen, L.C.S, Reimer, G.M., Wiggs, C.R., and Rice, C.A., 1988b, Map showing radon
       potential of rocks and soils in Montgomery County, Maryland:  U.S. Geological Survey
       Miscellaneous Field Studies Map MF-2043, scale 1:62,500.

Gundersen, Linda C.S., 1991, Radon in sheared metamorphic and igneous rocks, in Gundersen,
       Linda C.S., and Richard B. Wanty, eds., Field studies of radon in rocks, soils, and water:
     .  U.S. Geol.-Survey Bulletin no. 1971, p. 39-50.                        '
                                         II-I7      Reprinted from USGS Ppen-File Report 93-292

-------
Henry, Mitchell E., Kaeding, Margret E., and Monteverde, Donald, 1991, Radon in soil gas and
       gamma-ray activity of rocks and soils at the Mulligan Quarry, Clinton, New Jersey, in
       Gundersen, Linda C.S., and Richard B. Wanty, eds., Field studies of radon in rocks,
       soils, and water:  U.S. Geol. Survey Bulletin no. 1971, p. 65-75.

Klusman, R. W., and Jaacks, J. A., 1987, Environmental influences upon mercury, radon, and
       helium concentrations in soil gases at a site near Denver, Colorado: Journal of
       Geochemical Exploration, v. 27, p. 259-280.

Kovach, E.M., 1945, Meteorological influences upon the radon content of soil gas: Transactions,
       American Geophysical Union, v. 26, p. 241-248.

Kunz, C, Laymon, C.A., and Parker, C., 1989, Gravelly soils and indoor radon, in Osborne,
       M.C., and Harrison, J., eds., Proceedings of the  1988 EPA Symposium on Radon and
       Radon Reduction Technology, Volume  1: U.S. Environmental Protection Agency Report
       EPA/6QO/9-89/006A, p. 5-75-5-86.

Muessig, K., and Bell, C., 1988, Use of airborne radiometric data to direct testing for elevated
       indoor radon: Northeastern Environmental Science, v. 7, no. 1, p. 45-51.

Ronca-Battista, M., Moon, M., Bergsten, J., White, S.B., Holt, N.t and Alexander, B., 1988,
     ,  Radon-222 concentrations in the United States—Results of sample surveys in five states:
       Radiation Protection Dosimetry, v. 24,  p. 307-312.                                  •

Rose, A.W., Washington, J.W., and Greeman, D.J.,  1988, Variability of radon with depth and  .
       season in a central Pennsylvania soil developed on limestone: Northeastern Environmental
       Science, v. 7, p. 35-39.

Schery, S.D., Gaeddert, D.H., and Wilkening,  M.H., 1984, Factors affecting exhalation of radon
       from a gravelly sandy loam: Journal of Geophysical Research, v. 89, p. 7299-7309.

Schumann, R.R., and Owen, D.E., 1988, Relationships between geology, equivalent uranium
       concentration, and radon in soil gas, Fairfax County, Virginia: U.S. Geological Survey
       Open-File Report 88-18,28 p.

Schumann, R.R., and Gundersen, L.C.S., 1991, Regional differences in radon emanation ~
       coefficients in soils:  Geological Society of America Abstracts With Programs, V. 23,
       no.  1, p. 125.                                     .

Schumann, R.R., Peake, R.T., Schmidt, K.M., and Owen, D.E., 1991, Correlations of soil-gas
       and indoor radon with geology in glacially derived soils of the northern Great Plains, in
       Proceedings of the 1990 International Symposium on Radon and Radon Reduction
       Technology, Volume 2, Symposium Oral Papers: U.S. Environmental Protection Agency
       report EPA/600/9-9 l/026b, p. 6-23-6-36.
                                         IJ-18      Reprinted from USGS Open-File Report 93-292

-------
Schumann, R.R., Owen, D.E., and Asher-Bdlinder, S., 1992, Effects of weather and soil
       characteristics on temporal variations in soil-gas radon concentrations, in Gates, A.E., and
       Gundersen, L.C.S., eds., Geologic controls on radon: Geological Society of America
       Special Paper 271, p, 65-72.

Sextro, R.G., Moed, B.A., Nazaroff, W.W., Revzan, K.L., and Nero, A.V., 1987,
       Investigations of soil as a source of indoor radon, in Hopke, P.K., ed., Radon and its
       decay products: American Chemical Society Symposium Series 331, p. 10-29.

Sterling, R., Meixel, G., Shen, L., Labs, K., and Bligh, T., 1985, Assessment of the energy
       savings potential of building foundations research:  Oak Ridge, Tenn., U.S. Department of
       Energy Report ORNL/SUB/84-0024/1.

Smith, R.C,, II; Reilly, M.A., Rose,: A,W.,  Barnes, J.H., and Berkheiser, S.W.,  Jr., 1987,
       Radon: a profound case: Pennsylvania Geology, v. 18, p. 1-7.

Tanner, A.B., 1964, Radon migration in the ground:  a review,in Adams, J.A.S., and Lpwder,
       W.M., eds., The natural radiation environment: Chicago, 11., University of Chicago
       Press, p. 161-190.                          '            '

Tanner, A.B., 1980, Radon migration in the ground: a supplementary review, in GeseE, T.F.,-
      , and Lowder, W.M. (eds), Natural radiation environment ffl, Symposium proceedings,
       Houston, Texas, v. 1, p. 5-56.

U.S. Department of Agriculture, 1987, Principal kinds of soils: Orders, suborders, and great
       groups: UJS. Geological Survey, National Atlas of the United States of America, sheet
       38077-BE-NA-07M-00, scale 1:7,500,000.   l                                .    '

U.S. Department of Energy, 1976, National Uranium Resource Evaluation preliminary report,
       prepared by the U.S. Energy Research and Development Administration, Grand Junction,
    ,   Colo.: GJO-11(76).

Wanty, Richard B., and Schoen, Robert, 1991, A review of the chemical processes affecting the
       mobility of radionuclides in natural waters, with applications, in Gundersen, Linda C.S.,
       and Richard B. Wanty, eds., Field studies of radon in rocks, soils, and water: U.S.
    .   Geological Suryey Bulletin no. 1971, p. 183-194.   ,   ,,

Washington, J.W., and Rose, A.W., 1990, Regional and temporal relations of radon in soil gas to
       soil temperature and moisture:  Geophysical Research Letters, v. 17, p. 829-832.

White, S.B., Bergsten, J.W., Alexander, B.V., and Ronca-Battista, M., 1989, Multi-State
      .surveys of indoor 222Rn:  Health Physics* v. 57, p. 891-896.
                                         II-19     Reprinted from USGS Open:Fite Report 93-292

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                                               APPENDIX  A
                                      GEOLOGIC TIME SCALE
Subdivisions {and their symbols)
Eon or
Eonothtm
Phantrczoic2

Prottrozoie
ipi


Arches n
f&i

Era or
Erathem
Cenozoic J
(CD
Mesozoic2
(Md
Ja!eo20!c
(Pi)


. U". H*
PlOt*IGl&C i2\
M«jo.i
Pnwaiaie fYl
lirty
Presets* tXi
L«f
Arefw«« CWJ
WicdH
A/eh*»n IV)
£»"₯
Aren»§n
Permian
. JPJ
Pennsylvanian
Csrboniferous 
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                                    APPENDIX  B
                               GLOSSARY OF TERMS
Units of measure
pCi/L (picocuries per liter)- a unit of measure of radioactivity used to describe radon
concentrations in a volume of air. One pieoeurie (10~12 curies) is equal to about 2,2 disintegrations
of radon atoms per minute. A liter is about 1.06 quarts. The average concentration of radon in
U.S. homes measured to date is between 1 and 2 pCi/L.                .

Bq/m3 (Becquerels per cubic meter)- a metric unit of radioactivity used to describe radon       ,
concentrations in a volume of air. One becquerel is equal to one radioactive disintegration per
second. One"pCi/L is equal to 37 Bq/m3.

ppm (parts per million)- a unit of measure of concentration by weight of an element in. a
substance, in this case, soil or rock.  One ppm of uranium contained in a ton of rock corresponds
to about 0.03 ounces of uranium.  The average concentration of uraniufn,in soils in the United
States is between 1 and 2 ppm.                 "

in/hr (inches per hour)- a unit of measure used by soil scientists and engineers to describe the
permeability of a soil to water flowing through it, It is measured by digging a*hole 1 foot (12
inches) square and one foot deep, filling it with water, and measuring the time it takes for the water
to drain from the hole. The drop in height of the water level in the hole, measured in inches, is
then divided by the time (in hours) to determine the permeability. Soils range in permeability from
less than 0.06 in/hr to greater than 20 in/hr, but most soils in .the United States have permeabilities
between these two extremes.                                     '.'.-.          -
Geologic terms and terms related to the study of radon                       Vi     ,  ,

aerial radiometric, aeroradiometrie survey A survey of radioactivity, usually gamma rays,
taken by an aircraft carrying a gamma-rayspectrometer pointed at the ground surface.
                              » •* -    "        -         =                v.*1

alluvial fan A low, widespread mass of loose rock and soil material, shaped like an open fan
and deposited by a stream at the point where it flows from a narrow mountain valley out onto a
plain or broader valley. May also form at the junction with larger streams or when the gradient of
the stream abruptly decreases.        "      .
              I  ;V   ''•,-.               -              .        .          • '  ' . .
alluvium, alluvial General terms referring to unconsolidated detrital material deposited by a
stream or other body pf running water.

alpha-track detector A passive radon measurement device consisting of a plastic film that is
sensitive to alpha particles.  The film is etched with acid in a laboratory after it is exposed. The
etching reveals scratches, .or "tracks", left by the alpha particles resulting from radon decay, which
can then be counted to calculate the radon concentration.  Useful for long-term (1-12 months)
radon tests.                               .                              S!          •

amphibolite A mafic metamorphic rock consisting maMy of pyroxenes and(or) amphibole and
plagioclase.                                                 ,              ^
                                          11-21      Reprinted from USGS Open-File Report 93-292

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argillite, argillaceous Terms referring to a rock derived from clay or shale, or any sedimentary
rock containing an appreciable amount of clay-size material, i.e., argillaceous sandstone,

arid Term describing a climate characterized by dryness. or an evaporation rate that exceeds the
amount of precipitation.

basalt A general term for a dark-colored mafic igneous rocks that may be of extrusive origin,
such as volcanic basalt flows, or intrusive origin, such as basalt dikes.

batholith A mass of plutonic igneous rock that has more than 40 square miles of surface
exposure and no known bottom.

carbonate A sedimentary rock consisting of the carbonate (COa) compounds of calcium,
magnesium, or iron, e.g. limestone and dolomite.

carbonaceous Said of a rock or sediment that is rich in carbon, is coaly, or contains organic
matter.

charcoal canister A passive radon measurement device consisting of a small container of
granulated activated charcoal that is designed to adsorb radon.  Useful for short duration (2-7 days)
measurements only. May be referred to as a "screening" test

chert A hard, extremely dense sedimentary rock consisting dominantly of interlocking crystals of
quartz. Crystals are not visible to the naked eye, giving the rock a milky, dull luster. It maybe
white or gray but is commonly colored red, black, yellow, blue, pink, brown, or green.

clastic pertaining to a rock or sediment composed of fragments that are derived from preexisting
rocks or minerals. The most common clastic sedimentary rocks are sandstone and shale.

clay A rock containing clay mineral fragments or material of any composition having a diameter
less than 1/256 mm.

clay mineral One of a complex and loosely defined group of finely crystalline minerals made up
of water, silicate and aluminum (and a wide variety of other elements). They are formed chiefly by
alteration or weathering of primary silicate minerals. Certain clay minerals are noted for their small
size and ability to absorb substantial amounts of water, causing them to swell. The change in size
that occurs as these clays change between dry and wet is referred to as their "shrink-swell"
potential.

concretion A hard, compact mass of mineral matter, normally subspherical but commonly
irregular in shape; formed by precipitation from a water solution about a nucleus or center, such as
a leaf, shell, bone, or fossil, within a sedimentary or fractured rock.

conglomerate A coarse-grained, clastic sedimentary rock composed of rock and mineral
fragments larger than 2 mm, set in a finer-grained matrix of clastic material.

cuesta A hill or ridge with a gentle slope on one side and a steep slope on the other. The
formation of a cuesta is controlled by the different weathering properties and the structural dip of
the rocks forming the hill or ridge.

daughter product A nuclide formed by the disintegration of a radioactive precursor or "parent"
atom.
                                          11-22      Reprinted from USGS Open-File Report 93-292

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delta, deltaic Referring to a low, flat, alluvial tract of land having a triangular or fan shape,
located at or near the mouth of a river. It results from the accumulation of sediment deposited by a
river at the point at which the river loses its ability to transport the sediment, commonly where a
river meets a larger body of water such as a lake or ocean,             .
dike A tabular igneous intrusion of rock, younger than the surrounding rock, that commonly cuts
across the bedding or foliation of the rock it intrudes,                              .
dibrite A plutonic igneous rock that is medium in.color and contains visible dark minerals that
make up less than 50% of the rock.  It also contains abundant sodium plagioclase and minor -
quarto  ,                          •               .               .
dolomite A carbonate sedimentary rock of which more than 50% consists of the mineral dolomite
(CaMg(CO3)2), and is commonly white, gray, brown, yellow, of pinkish in color,
drainage The manner in which the waters of an .area pass, flow off of,, or flow into the soil.
Also refers to the water features of an area, such as lakes and rivers, that drain it.
eolian Pertaining to sediments deposited by the wind.           •     .
esker A long, narrow, steep-sided ridge composed of irregular beds of sand and gravel deposited
by streams beneath a glacier and left behind when the ice melted.
evapotranspiration Loss of water from a land area by evaporation from the; soil and.
.transpiration from plants,
extrusive Said of igneous rocks that have been erupted onto the surface of the Earth.
fault, A fracture or zone of fractures in rock or sediment along which .there has been movement
fluvial, fluvial deposit Pertaining to sediment that has been deposited by a river or stream.
foliation A linear feature in a rock defined by both mineralogic and structural characteristics.  It
may be formed during deformation or metamorphism.                         ..•-,.
formation A mappable body of rock having similar characteristics.                  -
glacial deposit Arty sediment transported and deposited by a glacier or processes associated
with glaciers, such as glaciofluvial sediments deposited by streams flowing from melting glaciers.
gneiss A rock formed by metamorphism in which bands and lenses of minerals of similar
composition alternate with bands and lenses of different composition, giving the rock a striped or
"foliated" appearance.
granite Broadly applied, any coarsely crystalline, quartz- and feldspar-bearing igneous plutonic
rock. Technically, granites have between 10 and 50% quartz, and alkali feldspar comprises at least
65% of the total feldspar.            •
gravel  An unconsolidated, natural accumulation of rock fragments consistmg, predominantly of
particles greater than 2 mm in size.              .                  .         •  .    .
heavy minerals Mineral grains in sediment or sedimentary rock having higher than average
specific gravity. May form layers and lenses because of wind or water sorting by weight and size
                                          11-23     Reprinted from USGS Open-File Report 93-292

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and may be referred to as a "placer deposit." Some heavy minerals are magnetite, garnet, zircon,
monazite, and xenotime.

igneous Said of a rock or mineral that solidified from molten or partly molten rock material. It is
one of the three main classes inio which row~> are divk _, 
-------
;  physiographic province A region in which all parts are similar in geologic structure and
  climate, which has had a uniform geomorphic history, and whose topography or landforms differ
  significantly from adjacent regions.
  placer deposit See heavy minerals                                       l
  residual Formed by weathering of a material in place,
  residuum Deposit of residual material.
  rhyolite An extrusive igneous rock of volcanic origin, compositionally equivalent to granite.
  sandstone A clastic sedimentary rock composed of sand-sized rock and mineral material that is
  more of less firmly cemented. Sand particles range from 1/16 to 2 mm in size.
  schist A strongly foliated crystalline rock, formed by metamorphism, that can be readily split intd
  thin flakes or slabs.  Contains mica; minerals are typically aligned.
  screening level Result of an indoor radon test taken with a charcoal canister or similar device,
  for a short period of time, usually less than seven days. May indicate the potential for an indoor.
  radon problem but does, not indicate annual exposure to radon,
  sediment Deposits of rock and mineral particles or fragments originating from material that is
  transported .by air, water or ice, or that accumulate by natural chemical precipitation or secretion of
  organisms.                        '..._''.
  semiarid Refers to a climate that has slightly more precipitation than an arid climate.     .
  shale A fine-grained sedimentary rock formed from solidification (lithification) of clay or mud.
  shear zone Refers to a roughly linear zone of rock that has been faulted by dmtile or non-ductile
  processes in Which the rock is sheared and both sides are displaced relative to one another.
  shrink-swell clay. See clay mineral.
  siltstone A fine-grained clastic sedimentary rock composed of silt-sized rock and mineral
  material and more or less firmly cemented. Silt particles range from 1/16 to 1/256 mm in size.
  -sinkhole A roughly circular depression in a karst area measuring meters to tens of meters in
  diameter. It is funnel shaped and is formed by collapse of the  surface material into an underlying  .
  void created by the dissolution of carbonate rock.                          ,.,'-.
  slope An inclined part of the earth's surface.                         *   •     •
  solution cavity  A hole, channel or. cave.-like cavity formed  by dissolution of rock.
-  stratigraphy The study Of rock strata; also refers to the succession of rocks of a particular area.
  surficial materials Unconsolidated glacial, wind-, or waterborne deposits occurring uu the
  earth's surface.                   •
  tablelands General term for a  broad, elevated region with a nearly level surface of considerable
  extent.                 .  ,               •              '.       '  -  •  .
                                            TL-25     Reprinted from USGS;Open-FileReport 93-292

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terrace gravel  Gravel-sized material that caps ridges and terraces, left behind by a stream as it
cuts down to a lower level.

terrain A tract or region of the Earth's surface considered as a physical feature or aft ecological
environment

till Unsorted, generally unconsolidated and unbedded rock and mineral material deposited directly
adjacent to and underneath a glacier, without reworking by meltwater.  Size of grains varies greatly
from clay to boulders.

uraniferous Containing uranium, usually more than 2 ppm.

vendor data Used in this report to refer to indoor radon data collected and measured by
commercial vendors of radon measurement devices and/or services.

volcanic Pertaining to the activities, structures, and extrusive rock types of a volcano.

water table The surface forming the boundary between the zone of saturation and the zone of
aeration; the top surface of a body of unconfined groundwater in rock or soil.

weathering The destructive process by which earth and rock materials, on exposure to
atmospheric elements, are changed in color, texture, composition, firmness, or form with little or
no transport of the material.
                                          n-26     Reprinted from USGS Open-FEe Report 93-292

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                                            APPENDIX  C
                                   EPA REGIONAL OFFICES
EPA   Regional  Offices
State
EPA  Region
EPA Region 1
JFK Federal Building
Boston, MA 02203   ,
(617) 565-4502

EPA Region 2
(2A1R;RAD)
26 Federal Plaza
New York,'NY 10278
(212)264-4110

Region 3 (3AH14)
841 Chestnut Street
Philadelphia, PA 19107
(215) 597-8326

EPA Region 4
345 Courtland Street, N.E.
Atlanta, GA 30365
(404) 347-3907

EPA Region 5 (5AR26)
77 West Jackson Blvd.
Chicago,  IL 60604-3507
(312) 886-6175

EPA Region 6 (CT-AS)
1445 Ross Avenue
Dallas, TX 75202-2733
(214) 655-7224

EPA Region 7
726 Minnesota Avenue
Kansas City, KS 66101
(913) 551-7604

EPA Region 8
 (8HWM-RP)
999  18th Street
One Denver Place, Suite 1300
Denver, CO 80202-2413
(303) 293-1713
                  •*   *
EPA Region 9 (A-3J
75 Hawthorne Street
San Francisco, CA 94105
(415) 744-1048
                f
EPA Region 10
 1200 Sixth Avenue
Seattle, WA 98101
 (202) 442-7660
Alabama	4
Alaska	,-..,	',.,.. 10
Arizona	,,	9
Arkansas	..,,.	,.,,....,6
California	9
Colorado.....,.;.......	8
Connecticut	;	1
Delaware.........	.....3
District of Columbia	3
Florida	4
Georgia	4
Hawaii	9
Idaho	„	10
Illinois..	;	...,5
Indiana	•.»	^	...5
Iowa	.,...»	i.."......	:7
Kansas	.'........-.	,	7
Kentucky	.....4
Louisiana	..A	*....6
Maine	.-	1
Maryland	,.	,	3
Massachusetts	1
Michigan	..'—	,5
Minnesota.....	.,",,:,....5
Mississippi	,',,.4
Missouri	,	7-
Montana	8
Nebraska,	......."	.....7
Nevada....		9.
New Hampshire	1
New  Jersey	»:	2
New Mexico..,.,	;,6
New York	2
North  Carolina	....4
North  Dakota	8
Ohio	....:...'.	5
Oklahoma	6
Oregon	10
Pennsylvania.,..	'.3
Rhode Island	.•	1
South  Carolina..;	,	™...4  .
South  Dakota...	.......8
Tennessee	4
Texas	,	6
Utah....	.....8
Vermont.....	'....,...1
Vkginia	...3
Washington	10
West Vkginia	'.	....".,..3
Wisconsin	•...	.....5
Wyoming	8
                                                  H-27       Reprinted from USGS Open-File Report 93-292

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                                STATE RADON  CONTACTS
                                            May, 1993
Alabama       James McNees
               Division of Radiation Control
               Alabama Department of Public Health
               State Office Building
               Montgomery, AL 36130
               (205)242-5315
               1-800-582-1866 in state

Afasfa         Charles Tedfoid
               Department of Health and Social
                 Services
               P.O. Box 110613
               Juneau.AK 99811-0613
               (907)465-30*19
               1-800-478-4845 in state

Arizona        John Stewart
               Arizona Radiation Regulatory Agency
               4814 South 40th St.
               Phoenix, AZ 85040
               (602) 255-4845
Arkansas       LeeGershner
               Division of Radiation Control-
               Department of Health
               4815 Markham Street, Slot 30
               Little Rock, AR 72205-3867
               (501) 661-2301
California      J. David Quinton
               Department of Health Services
               714 P Street, Room 600
               Sacramento, CA 94234-7320
               (916) 324-2208
               1-800-745-7236 in state
Colorado      • LindaMartin
               Department of Health
               4210 East llth Avenue
               Denver, CO 80220
               (303)692-3057
               1-800-846-3986 in state
 Connecticut Alan J. Siniscalchi
            Radon Program
            Connecticut Department of Health
              Services
            150 Washington Street
            Hartford, CT 061064474
            (203) 566-3122

   Delaware MaraiG.Rejai
            Office of Radiation Control
            Division of Public Health
            P.O. Box 637
            Dover," DB 19903
            (302) 736-3028
            1-800-554-4636 In State

    District Robert Davis
of Columbia DC Department of Consumer and
              Regulatory Affairs
            614 H Street NW
            Room 1014
            Washington, DC 20001
            (202)727-71068

     Florida N. Michael Gilley
            Office of Radiation Control
            Department of Health and
              RehabffitativeServices
            1317 Winewood Boulevard
            Tallahassee, Ft 32399-0700
            (904)488-1525
            1-800-543-8279 in state
            Richard Schreiber
            Georgia Department of Human
              Resources
            878 Peachtree St, Room 100
            Atlanta, GA 30309
            (404) 894-6644
            1-800-745-0037 in state
     Hawaii Russell Takata
            Environmental Health Services
              Division
            591 Ala Moana Boulevard
            Honolulu, ffl 96813-2498
            (808) 586-4700
                                              H-28
      Reprinted from USGS Open-File Report 93-292

-------
Idaho
Iowa
Kansas
Kentucky
PatMcGavarn
Office of Environmental Health
450 West'State Street
Boise, ID 83720
(208)334-6584
1-80Q-W5-8647 in state
               Richard Allen '
               Illinois Department of Nuclear Safety
               1301 Outer Park Drive
               Springfield, IL 62704
               (217)524-5614
               1-800-325-1245 in state
Lorand Magyar
Radiological Health Section
Indiana State Department of Health
1330 West Michigan Street
P.O. Box 1964
Indianapolis, IN 46206
(317)633-8563
1-800-272-9723 In State

Donald A. Hater
Bureau of Radiological Health
Iowa Department of Public Health
Lucas State Office Building
Des Moines, IA 50319-0075"
(515) 281-3478
1-800-383-5992 In State    '

Harold Spiker
Radiation Control Program
Kansas Department of Health and
  Environment   ,           -
109 SW 9th Street
6th Floor Mills Building
Topeka, KS 66612   .
(913)296-1561

JeanaPheJps
Radiatipn Control Branch
Department of Health Services
Cabinet for Human Resources
275 East Main Street
Frankfort, KY 40601
(502)564-3700
    Louisiana  Matt Schlenker
              Louisiana Department of
                Environmental Quality
              P.O. Box 82135
              Baton Rouge, LA 70884-2135
              (504)925-7042
              1-800-256-2494 in state

       Maine  BobStilwell              i
              Division of Health Engineering
              Department of Human Services
       ,       State House, Station 10
              Augusta, ME 04333
              (207)289-5676
              1-800-232-0842 in state

    Maryland  Leon J. Raehuba
              Radiological Health Program
              Maryland Department of the
            ;    Environment
              2500 Broening Highway
              Baltimore, MD 21224
              (410)631-3303*
           :   1-800-872-3666 MState

Massachusetts  William J. Bell
              Radiation Control Program
              Department of Public Health
              23 Service Center
              Northampton, MA 01060
              (413)586-7525
              1-800-445-1255 in state
                          •'' ':<•»
    Michigan  SueHendeishott
              Division of Radiological Health
              Bureau of Environmental and
        .        Occupational Health
             •3423 North Logan Street
              P.O. Box 30195
              Lansing, MI 48909
              (517)335-8194     .

    Minnesota  LauraQatmann
              Indoor Air Quality Unit
              925 Delaware'Street, SB
              P.O. Box 59040
              Minneapolis, MN 55459-0040
              (612) 627-5480
              1-800-798-9050 in state
                                                11-29      Reprinted from USGS Open-File Report 93-292

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Mississippi
Missouri
Montana
               Silas Anderson
               Division of Radiological Health
               Department of Health
               3 150 Lawson Street
               P.O. Box 1700
               Jackson, MS 39215-1700
               (601) 354-6657
               1-800-626-7739 in state

               Kenneth V. Miller
               Bureau of Radiological Health
               Missouri Department of Health
               1730 last Elm
               P.O. Box 570
               Jefferson City, MO 65102
               (314) 751-6083
               1-800-669-7236 In State

               Adrian C. Howe
               Occupational Health Bureau
               Montana Department of Health and
                 Environmental Sciences
               Cogswell Building A113
               Helena, MT 59620
               (406)444-3671
               Joseph Milone
               Division of Radiological Health
               Nebraska Department of Health
               301 Centennial Mall, South
               P.O. Box 95007
               Lincoln, NE 68509
               (402)471-2168
               1-800-334-9491 In State

               Stan Marshall
               Department of Human Resources
               505 East King Street
               Room 203
               Carson City, NV 89710
               (702) 687-5394
New Hampshire David Chase
               Bureau of Radiological Health
               Division of Public Health Services
               Health and Welfare. Building
               Six Hazen Drive
               Concord, NH 03301
               (603) 271-4674    .
               1-800-852-3345 x4674
Nebraska
   New-Jersey Tonalee Carlson Key
              Division of Environmental Quality
              Department of Environmental
                Protection
              CN415
              Trenton, NJ 08625-0145
              (609) 987-6369
              1-800-648-0394 in state

  New Mexico William M. Floyd
              Radiation Licensing and Registration
                Section
              New Mexico Environmental
                Improvement Division
              1190 Sf. Francis Drive
              Santa Fe,NM 87503
              (505) 827-4300

    New York William J. Condon
              Bureau of Environmental Radiation
                Protection
              New York State Health Department
              Two University Place
              Albany, NY 12202
              (518)458-6495
              1-800-458-1158 in state

North Carolina Dr. Felix Fong
              Radiation Protection Division
              Department of Environmental Health '
                and Natural Resources
              701 Barbour Drive
              Raleigh, NC 27603-2008 '
              (919) 571-4141
              1-800-662-7301 (recorded info x4196)

 North Dakota Arlen Jacobson
              North Dakota Department of Health
              1200 Missouri Avenue, Room 304
              P.O. Box 5520
              Bismarck, ND 58502-5520
              (701)221-5188

        Ohip Marcie Matthews
              Radiological Health Program
              Department of Health
              1224 Kinnear Road - Suite 120
              Columbus, OH 43212
              (614)644-2727
              1-800-523-4439 in state
                                               n-30      Reprinted from USGS Open-File Report 93-292

-------
Oklahoma
Oregon
Pennsylvania
PuertoRico
Rhode Island
South Carolina
 Gene Smith
 Radiation Protection Division
 Oklahoma State Department of
   Health
 P.O. Box 53551
 Oklahoma City, OK 73152
 (405) 271-5221
 George Toombs       '   ',
 Department of Human Resources
 Health Division
 1400 SW 5th Avenue
 Portland, OR 87201
 (503)7314014
, Michael Pyles
 Pennsylvania Department of
   Environmental Resources
 Bureau of Radiation Protection
, P.O. Box 2063   '          .
 Harrisburg, PA 17120
 (717)783-3594
 1-800-23-RADON In State

 David Saldana
 Radiological Health Division
 G.P.O. Call Box 70184
 Rio Kedras, PuertoRico 00936
 (809)767-3563,
 Edmund Arcahd
 Division of Occupational Health and
  .Radiation
 Department of Health
 205 Cannon Building
 Davis Street
 Providence, RI02908  ' ,  '
 (401)277-2438.  .          .
               Bureau of Radiological Health
               Department of Health and
                 Environmental Control
               2600 Bull Street
               Columbia, SC 29201
               (803)734-4631
               1-800-768-0362 ,
Sooth Dakota MikePoehop
             Division of Environment Regulation
             Department of Water and Natural
               Resources             :
             Joe Foss Building, Room 217
             523 E. Capitol
        ,     Pierre, SD 57501-3181
             (605) 773-3351,
            i        \        - ...

   Tennessee Susie Shimek
             Division of Air Pollution Control
             Bureau of the Environment
             Department of Environment and
               Conservation    " ,
             Customs House, 701 Broadway
            . Nashville, TN 37219-5403
             (615) 532-0733
             1-800-232-1139 in state
             Gary Smith
             Bureau of Radiation Control
             Texas Department of Health
             1100 West 49th Street
             Austin, TX 78756-3189
             (512) 834-6688
        Utah John Hultquist                '
             Bureau of Radiation Control
             Utah State Department of Health . ,-
  .  '.  .      288North, 1460West
             P.O. Box 16690              -
             Salt Lake City, UT 84116-0690
             (801) 5364250

    Vermont Paul demons
      :'      Occupational and Radiological Health
               Division                   ,',
             Vermont Department of Health
          '   10 Baldwin Street
             Montpelier, "VT 05602
             (802)828-2886
             1-800-640-0601 in state

Virgin Islands Contact the U.S. Environmental
             Protection Agency, Region II ,
             in New York
             (212)2644110
                                               11-31      Reprinted from USGS Open-File Report 93-292

-------
Virginia        Shelly Ottenbrite
               Bureau of Radiological Health
               Department of Health
               109 Governor Street
               Richmond, VA 23? \9
               (804) 786-5932
               1-800-468-0138 in state

Washington     KateColeman
               Department of Health
               Office of Radiation Protection
               Airdustrial Building 5, LE-13
               Olympia,WA 98504
               (206)7534518
               1-800-323-9727 In State

West Virginia   BeattieL. DeBord
               Industrial Hygiene Division
               West Virginia Department of Health
               151 llth Avenue
               South Charleston, WV 25303
               (304) 558-3526
               1-800-922-1255 In State

Wisconsin      Conrad Weiffenbach
               Radiation Protection Section
               Division of Health
               Department of Health and Social
                 Services
               P.O. Box 309
               Madison, WI53701-0309.
               (608) 267-4796
               1-800-798-9050 in state

Wyoming      Janet Hough
               Wyoming Department of Health and
                 Social Services
               Hathway Building, 4th Floor
               Cheyenne, WY 82002-CT710
               (307) 777-6015
               1-800-458-5847 in  state
                                                11-32      Reprinted from USGS -Open-File Report 93-292

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                            STATE  GEOLOGICAL SURVEYS
                                            May, 1993
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Ernest A. Mancini
Geological Survey of Alabama
P.O. Box 0
420 Haekberry Lane
Tuscaloosa, AL 35486-9780
(205)349-2852      •

Thomas E. Smith
Alaska Division of Geological &
  Geophysical Surveys
794 University Ave., Suite 200
Fairbanks, AK  99709-3645
(907)479-7147

Larry D. Fellows
Arizona Geological Survey
845 North Park Ave., Suite 100
Tucson, AZ 85719
(602)882-4795
Norman F. Williams
Arkansas GeoIogical,Commission
Vardelle Parham Geology Center
3815 West Roosevelt Rd.
Little Rock, AR 72204
(501) 324-9165           -

James F. Davis
California Division of Mines &
  Geology
801 K Street, MS 12-30
Sacramento, CA 95814-3531
(916)445-1923

Pat Rogers (Acting)
Colorado Geological Survey
1313 Sherman St., Rm 715
Denver, CO  80203       •
(303)866-2611  '
  **          ,      .
Richard C. Hyde
Connecticut Geological & Natural
  History Survey
165 Capitol Ave., Rm. 553
Hartford, CT 06106
(203)566-3540

Robert R. Jordan
Delaware Geological Survey
University of Delaware
 101 Penny Hall
Newark, DE 19716-7501
(302) 831-2833
                                                               Walter Schmidt
                                                               Florida Geological Si vey
                                                               903 W*. Tennessee St
                                                               Tallahassee, FL 32304-7700
                                                               (904)4884191
Georgia  William H.,McLemore
        Georgia Geologic Survey
      "  Rm. 400
        19 Martin Luther King Jr. Drl SW
        Atlanta, GA 30334                -
        (404)656-3214

 Hawaii  Manabu Tagomori
        Dept. of Land and Natural Resources
        Division of Water & Land Mgt
        P.O. Box 373
        Honolulu, HI
        (808)548-7539 '

  Idaho  Earl H. Bennett
    .    Idaho Geological Survey
        University of Idaho
        Morrffl Hall, Rm. 332
        Moscow, ID 83843
        (208) 885-7991               •  . .

 Illinois  Morris W. Leighton
        Illinois State Geological Survey
        Natural Resotte^a-Building
        615 East Peabody Dr.
        Champaign, IL 61820
        (217)333-4747    .   ;.

 Indiana  Norman C. Hester
        Indiana Geological Survey
        611 North Walnut Grove
        Bloomington, M47405
        (812) 855-9350  .

   Iowa  Donald L. Koch
        Iowa Department of Natural Resources
        Geological Survey Bureau
        109 Trowbridge Hall
        Iowa City, IA 52242-1319
       . (319) 335-1575

 Kansas  LeeC.Gerhard
        Kansas Geological Survey
        1930 Constant Ave., West Campus
        University of Kansas
        Lawrence,KS 66047.
        (913)864-3965     *
                                               II-33      Reprinted from USGS Open-File Report 93-292

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Mains
Michigan
Minnesota
Mississippi
Donald C. Haney
Kentucky Geological Survey
University of Kentucky
228 Mining & Mineral Resources
  Building
Lexington, KY 40506-0107 .
(606)257-5500

"William E. Marsalis
Louisiana Geological Survey  "
P.O. Box 2827
University Station
Baton Rouge, LA 70821-2827
(504)388-5320

Walter A, Anderson
Maine Geological Survey
Department of Conservation
State House, Station 22
Augusta, ME 04333
(207)289-2801
Emery T. Cleaves
Maryland Geological Survey
2300 St. Paul Street
Baltimore, MD 21218-5210
(410) 554-5500
Joseph A. Sinnott
Massachusetts Office of
  Environmental Affairs
100 Cambridge SL, Room 2000
Boston, MA 02202
(617)727-9800

R. Thomas Segall
Michigan Geological Survey Division
Box 30256
Lansing, Ml 48909
(517) 334-6923

Priscilla C'Grew
Minnesota Geological Survey
2642 University Ave.
St. Paul, MN 55114-1057
(612) 627-4780
S. Cragin Knox
Mississippi Office of Geology
P.O. Box 20307
Jackson, MS 39289-1307
(601)961-5500
      Missouri  James H. Williams
               Missouri Division of Geology St.
                 Land Survey
               111 Fairgrounds Road
               P.O. Box 250
               Rolla, MO 65401
               (314) 368-2100

      Montana  Edward T.Ruppel
               Montana Bureau of Mines & Geology
               Montana College of Mineral Science
                 and Technology, Main Hall
               Butte, MT 59701
               (406)496-4180

      Nebraska  Perry B. Wigley
               Nebraska Conservation & Survey
                 Division
               113 Nebraska Hall
               University of Nebraska
               Lincoln, ME 68588-0517
               (402)472-2410

       Nevada  Jonathan G. Price
               Nevada Bureau of Mines & Geology
               Stop 178
               University of Nevada-Reno
               Reno, NV 89557-0088
               (702)784-6691

New Hampshire  Eugene L. Boudette
               Dept. of Environmental Services
               117 James Hall
               University of New Hampshire
            '   Durham, NH 03824-3589
               (603)862-3160

    Newlersey  Haig F. Kasabach
               New Jersey Geological Survey
               P.O. Box 427
               Trenton, NJ 08625
               (609)292-1185

   NewMexico  Charles E, Chapin
               New Mexico Bureau of Mines &
                 Mineral Resources
               Campus Station
               Socorro.NM 87801
               (505) 835-5420

     New York  Robert H. Fakundiny
               New York State Geological Survey
               3136 Cultural Education Center
               Empire State Plaza
               Albany, NY 12230
               (518)474-5816
                                11-34      Reprinted from USGS Open-File Report 93-292

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 North Carolina  Charles HL Gardner
               North Carolina Geological Survey
               P.O. Box 27687   •
               Raleigh, NC 27611-7687
             .  (919)733-3833

North Dakota    John P. Bluemle
               North Dakota Geological Survey
               eOOEastBlvd.
               Bismarck, ND 58505-0840
               (701)224-4109
Ohio    .      Thomas M. Berg
               Ohio DepL of Natural Resources
             '  Division of Geological Survey
               4383 Fountain Square Drive
               Columbus, OH 43224-1362
               (614)265-6576   "

Oklahoma      Charles J. Mankin
               Oklahoma Geological Survey
               Room N-131, Energy Center
               100E.Boyd        .
               Norman, OK 73019-0628
               (405)325-3031
               Donald A. Hull
               Dept. of Geology & Mineral Indust.
               Suite 965
               800 NE Oregon St. #28
               Portland, OR 97232-2162
               (503)731-4600           "
Pennsylvania    Donald M. HosMns
               Dept. of Environmental Resources
               Bureau of Topographic & Geologic
                 Survey              ,
               P.O. Box 2357
               Harrisburg, PA 17105-2357
               (717)787-2169  ,

Puerto Rico     Ramdn M. Alonso
               Puerto Rico Geological Survey
                 Division
               Box 5887
               Puerta de Tierra Station
               San Juan, P.R. 00906
               (809)722-2526

Rhode Island    J. Allan Cain
               Department of Geology
               University of Rhode Island
               315GreenHall
               Kingston, RI02881
               (401)792-2265
South Carolina  Alan-Jon W. Zupan (Acting)
               South Carolina Geological Survey
               5 Geology Road
               Columbia, SC 29210-9998
               (803)737-9440

  South Dakota  C.M. Christensen (Acting)
               South Dakota Geological Survey
               Science Center
               University of South Dakota
               VermilUon, SD 57069-2390
         •      (605) 677-5227

     Tennessee  Edward T.Luther
               Tennessee Division of Geology
               13th Floor, L & C Tower
               401 Church Street
              - Nashville, TN 37243-0445
               (615)532-1500

        Texas  William L. Fisher
               Texas Bureau of Economic Geology
               University of Texas
               University Station, Box X
               Austin, TX 78713-7508
               (512)471-7721        ,

         Utah  M. Lee Allison
               Utah Geological & Mineral Survey
               2363 S'. Foothm Dr.
             ,  Salt Lake City, UT 84109-1491
1               (801)467-7970
               Diane L. Conrad
               Vermont Division of Geology and
                 Mineral Resources
               103 South Main St.
               Waterbury.VT 05671
               (802)244-5164
      Virginia  Stanley S- Johnson
               Virginia Division of Mineral
                 Resources
               P.O. Box 3667
               Charlottesville, VA 22903
               (804)293-5121
   Washington  Raymond Lasmanis
               Washington Division of Geology &
                 Earth Resources
               Department of Natural Resources
               P.O. Box 47007
           .    Olympia, Washington 98504-7007
               (206)902-1450
                                               11-35      Reprinted from USGSOpen-Ffle Report 93-292

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  West Virginia  Larry D. Woodfork
               West Virginia Geological and
                 Economic Survey
               Mont Chateau Research Center
               P.O. Box 879
               Morgantown, WV 26507-0879
               (304)594-2331

Wisconsin      James Robertson
               Wisconsin Geological & Natural
                 History Survey
               381? Mineral Point Road
               Madison, WI 53705-5100
               (608)263-7384

Wyoming      Gary B. Glass
               Geological Survey of Wyoming
               University of Wyoming
               Box 3008, University Station
               Laramie, WY 82071-3008
               (307) 766-2286
                                              n-se
Reprinted fiom USGS Open-File Report 93-292

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              EPA REGION 7 GEOLOGIC RADON POTENTIAL SUMMARY
  •  ••    •       •      .     -      .   -       by         . -•             :_,    -    •
                R. Randall Schumann, James K. Otton, and Sandra L. Szarzi
                                 U.S. Geological Survey                           '

       EPA Region 7 includes the states of Iowa, Kansas, Missouri, and Nebraska.  For each
state, geologic radon potential areas were delineated and ranked on the basis of geologic, soil, .
housing construction, and other factors. Areas in which the average screening indoor radon level
of all homes within the area is estimated to be greater than 4 pCi/L were ranked high. Areas in
which the average screening indoor radon level of all homes within the area is estimated to be
between 2 and 4 pG/L were-ranked moderate/variable, and areas in which the average screening
indoor radon level of all homes within the area is estimated to be less than 2 pCi/L were ranked
low. Information on the data used and on the radon potential ranking scheme is given in the
introduction chapter. More detailed information on the geology and radon potential of each state in
Region 7 is given in the individual state chapters.  The individual chapters describing the geology
and radon potential of the four states in EPA Region 7, though mueh more detailed than this
summary, still are generalized assessments and there is no substitute for having a home tested.
Radon levels, both high and low, can be-quite localized, and within any radon potential area homes
with indoor radon levels both above and below the predicted average win likely be found.
       Figure 1 shows the geologic radon potential areas in EPA Region 7. Figure 2 shows  -
average screening indoor radon levels in EPA Region 7 by county. The data for each state are
from the State/EPA Residential Radon Survey and reflect screening charcoal canister
measurements. Figure 3 shows the geologic radon potential of areas in Region 7, combined and
summarized from the individual state chapters.  Many rocks and soils in EPA Region 7 contain
ample radon source material (uranium and radium) and have soil permeabilities sufficient to
produce moderate or high radon levels in homes. YThe following sections summarize  the geologic-
radon potential of each of the four states in Region 7. More detailed discussions may be found in
the individual state radon potential chapters for the states in Region 7.             ,.'•""

IOWA                 /                                          '

       Pre-Elinoian-age glacial deposits cover most of Iowa, and are at or near the surface in the
southern, northwestern, and much of the northeastern parts of the state. These deposits generally
consist of calcium-carbonate-rich loam and clay loam till containing pebbles arid cobbles of granite,
gabbro, basalt, rhyolite, greenstone, quartzite, chert, diorite, and limestone. Pre-IUinoian tills are
covered by from less than 1 m to more than 20 m of Wisconsinan loess (windblown silt) in
western, southern, and eastern Iowa. Dlinoian glacial deposits occur a relatively small area along
the Mississippi River in southeastern Iowa. These deposits consist of loamy to locally sandy till
containing clasts of limestone and dolomite, with lesser amounts of igneous and metamorphic
rocks, sandstone, and coal fragments,  fllinoian deposits are covered by 1-5 m of loess.
Wisconsinan drift is,represented by the Gary and Tazewell drifts, consisting of calcareous loamy
till containing clasts of shale, limestone, and dolomite, with minor amounts of basalt, diabase,
granite, chert, and sandstone. Gary drift (now called the Dows Formation),%hioh represents
deposits of the Des Moines lobe, is generally not loess-covered; Tazewell drift is covered by as
much as 2 m of loess.                              '                      .    -
                                          , ffl-1     Reprinted from USGS Open-File Report 93-292-G

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Figure 1. Geologic radon potential areas of EPA Region 7. See text for discussion of areas. 1,6-Pierre Shale; 2,5-Tertiary-
sedimentary rocks; 3-Sand Hills; 4,8,1l-Tertiary sedimentary rocks covered by varying thicknesses of loess; 7,13,16,21,23-loess-
covered glacial drift plains; 9-Cretaceous sedimentary rocks covered by varying thicknesses of loess; 10-dune sands in the Arkansas and
Cimarron river valleys; 12,15-area underlain by Pennsylvanian and Permian rocks; 14-part of the Mid-Gontinent Rift Zone; 17,22-
loess and glacial deposits along the Missouri River; 18-Des Moines lobe; 19-Iowan Surface; 20-Paleozoic Plateau; 24-unglaciated part
of the Osage Plain; 25-Qzark Plateau; 26,28-Area underlain by carbonate rocks; 27-St Francois Mountains; 29,-Coastal Plain.

-------
                                         Indoor Radon Screening .
                                      Measurements: Average (pCI/L)
    69
148
      35
                                              0.0 to 1,9
                                              4.1 to 9.9
                                              10.0 to 23.2
                                      48 f'l") - Missing Data (< 5 measurements)
Figure 2, Average screening indoor radon levels by county for EPA Region 7. Data from the State/EPA Residential Radon
Survey. Histograms in map legend indicate the number of counties in each measurement category.

-------
                                                      >A •- • *.*<*•.'• • "«s.1 *.*.*-t *A *.*•»•.'• *.*.*iV»A•.v*.'.• *» sA•.*.•.!«•• •-"Jb.ljAC*»* *t
GEOLOGIC RADON POTENTIAL (average sreening indoor radon level):

|   | LOW (<2 pCf/L)  ^ MODERATE/VARIABLE (2-4 pCi/L)  ^ HIGH (> 4 pCi/L)
 Figure 3. Geologic radon potential of EPA Region 7. Ranges next to each category label indicate the
 predicted average screening indoor radon level for all homes in each area.

-------
       The aeroradioactivity signature of surface deposits in Iowa, especially the Des Moines lobe
deposits and other areas in which the loess cover is dicontinuous or absent, seems lower than
would be expected in light of the elevated indoor radon levels. This may be because much of the
radium in the near-surface soil horizons may have been leached and transported downward in the
soil profile, giving a low surface radiometric signature while generating significant radon at depth
(1-2 m? or greater) to produce elevated indoor radon levels. For example, a large area of low
radioactivity (<1,5 ppm eU) in the northern part of the State corresponds roughly to the Des
Moines lobe and the lowan erosion surface, an area directly east of the Des Moines, lobe in
northeastern Iowa that is underlain by Pre-IUinoian glacial deposits and loess.  However, these
areas have high geologic radon potential. Most of the remainder of the State has eU values in the,
1.5-2.5 ppm range.  In general, soils developed from glacial deposits can be more rapidly leached
of mobile ions than their bedrock counterparts, because crushing and grinding of the roeks,by
glacial action gives soil weathering agents (mainly moisture), better access to soil and mineral grain
surfaces.  Grinding of the rocks increases the mobility of uranium and radium in the soils by    t
exposing them at grain surfaces, enhancing radionucHde mobility and radon emanation. In
addition, poorly-sorted glacial drift may in many cases have higher permeability than the bedrock
from which it is derived;  Cracking of clayey  glacial soils during dry periods can create sufficient
permeability for convective radon transport to occur. This may be an important factor causing -
elevated radon levels in areas underlain by clay-rich glacial deposits.                 •
       Loess-covered areas have a higher radiometric signature than loess-fee areas, and also
•appear to correlate roughly with higher average indoor radon levels than loess-free areas, although
all areas of Iowa have average indoor radon levels exceeding 4 pCi/L., The Loess-Covered Drift  -
Plains, which cover northwestern Iowa and all of southern Iowa, are underlain by Pre-IUinoian  .
and Illinoian glacial deposits, and loess.  The Loess-Covered Drift Plains have overall high radon
potential Valley bottoms with wet soils along the Mississippi and Missouri Rivers may have
locally moderate to low radon potential because the gas permeability of the soils is extremely low
due to the water filling the pore spaces.'                                         ,
       The Paleozoic Plateau, in northeastern Iowa, is underlain primarily by Ordovician
carbonate and Cambrian sandstone bedrock covered by varying amounts of Quaternary glacial
deposits and loess.  It was originally thought to have been unglaciated because it is deeply
dissected and  lacks  glacial landforms.  However, small patches of Pre-Dlinoian drift have been
preserved on uplands, indicating that at least part of the area had been glaciated. The Paleozoic
Plateau also has high geologic radon potential.  Soils developed from carbonate rocks are derived
from the residue that remains after dissolution of the calcium carbonate that fnakes.up the majority
of the rock, including heavy minerals and metals such as uranium, and thus they may  contain
somewhat higher concentrations of uranium or uranium-series radionuclides than the parent rock.
Residuum from weathered carbonate rocks may be a potential radon source if a structure is built on
such a residual soil, or if the residuum constitutes a significant part of a till or other surficial
deposit  In some areas underlain by carbonate bedrock, solution features such as sinkholes and :
caves increase the overall permeability of the  rocks in these areas and generally increase the radon
potential of these rocks, but few homes are built directly over major solution features.

KANSAS ..  .•.    -           .       .  •   .   •      ;..-..'   ,." •    ;     ,           ,

       Almost all of the bedrock exposed at the surface in Kansas consists of sedimentary units
ranging in age from Mississippian to Quaternary. Igneous rocks native to Kansas and exposed at
                                           , ffl-5    Reprinted from TJSGS Open-File Report 93-i92-G

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the surface are small localized exposures of Cretaceous lamproite in Woodsoa County and
Cretaceous Mmberlte in Riley County.  Sedimentary rocks of Mississippian age underlie the
extreme southeastern corner of the State, They consist primarily of limestones but also include
shale, dolomite, chert, sandstone, and siltstone. Pennsylvanian rocks underlie approximately the
eastern one-quarter of the State.  They consist of an alternating sequence of marine and nonmarine
shale, limestone, sandstone, and coal, with lesser amounts of chert and conglomerate. The shales
range from green and gray (low organic content) to black (organic rich). Permian rocks are
exposed in east-central and southern Kansas and consist of limestone, shale, gypsum, anhydrite,
chert, siltstone, and dolomite. Red sandstone and shale of Permian age underlie the Red Hills
along the southern border of Kansas.                         .     .
       The Mississippian, Pennsylvanian, and Permian rocks in eastern Kansas have relatively
low uranium contents, generally low to moderate permeability and have generally low to moderate
geologic, radon potential. Homes situated on Pennsylvanian and Permian carbonate rocks
(limestones and dolomites) may have locally elevated indoor radon levels if the limestones have
developed clayey residual soils and(or) if solution features (karst topography), are present in the
area.  Because of the geologic variability of these units, the Mississippian, Pennsylvanian, and
Permian rock outcrop area has been ranked moderate or variable in overall geologic radon
potential.  Homes sited on Pennsylvanian black shale units may be subject to locally high indoor
radon levels. This may be the     in the Kansas City area, part of which is underlain by black
shales.
       Some elevated indoor radon levels in the northern part of the Permian outcrop area,
specifically in Marshall, Clay, Riley, Geary, and Dickinson Counties, may be related to faults and
fractures of the Mid-Continent Rift and Nemaha Uplift Many of the subsurface faults reach and  •
displace the surface sedimentary rock cover, and the density and spacing of faults and fractures  .
within the rift zone is relatively high. Fault and shear zones are commonly areas of locally elevated
radon because these zones typically have higher permeability than the surrounding rocks, because
they are preferred zones of uranium mineralization, and because they are potential pathways
through which uranium-, radium-, and(or) radon-bearing fluids and gases can migrate.
       Cretaceous sedimentary rocks underlie much of north-central and central Kansas,.and
consist of green, gray, and black, shale, sandstone, siltstone, limestone, chalk, and chalky shale.
A discontinuous layer of loess of varying thickness covers the Cretaceous rocks in many areas,
particularly in the western part of the Cretaceous outcrop area. Cretaceous rocks in Kansas contain
sufficient uranium  to generate elevated indoor radon levels.  Soils developed on Cretaceous rocks
have low to moderate permeability, but the shale-derived soils with low permeability to water likely
have moderate permeability to soil gas when they are dry due to desiccation cracks. Areas
underlain by these rocks have an overall high radon potential. Tertiary rocks cover much of
western Kansas, though they are covered by loess deposits in many areas. Tertiary rocks consist
of nonmarine sandstone, siltstone, and shale; volcanic ash deposits; and unconsolidated gravel,
sand, sUt, and clay. Areas underlain by the Tertiary Ogalala Formation have a-moderate
radioactivity signature and a moderate to high radon potential.
       Loess ranging from 0 to more than 30 meters in thickness covers as much as 65 percent of
the surface of Kansas and is thickest and most extensive in the western and north-central parts of
the State and in proximity to glacial deposits in the northeastern corner of the State. Possible
sources for the loess include: (1) glacial outwash, (2) sand dunes in the Arkansas and Cimarron
River valleys or elsewhere (such as the Sand Hills of Nebraska), and (3) erosion of Tertiary
sedimentary rocks by wind and rivers.  Radon potential of loess-mantled areas depends on the
                                           ffl-6     Reprinted from USGS Open-File Report 93-292-O

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 thickness and source of the loess. In areas of very thin-loess cover, the radpn potential of the
 underlying bedrock is significant, and the loess both generates radon and transmits radon from the
 underlying bedrock, whereas if the loess is more than 7-10 m thick, it is probably the sole radon
 source for homes in the area. Loess-covered areas underlain by Cretaceous and Tertiary bedrock
 appear to have variably moderate to high radon potential across the State, and locally elevated
 indoor radon levels may be expected anywhere within areas underlain by these units. Areas
 underlain by loess-covered Pennsylvanian and Permian rocks appear to generate mainly moderate
 to locally elevated indoor radon levels.        .
       Areas of windblown sand in the Arkansas and Cimarron River valleys have low uranium
 contents and low radon potential, but few homes are built directly oh the sand dunes. The dune
 sands are intermixed with loess in parts of the Arkansas and Cifnarron valleys, and the radon
 potential may be related to the relative proportions of sand, loess, and bedrock within these areas.
, Areas underlain by dune sand are expected to have lower radon levels, areas with considerable
 loess content are expected to have moderate to locally elevated radon levels. Where sand or loess
 is thin or absent, the radon levels in homes on Tertiary or Cretaceous bedrock are also expected to
 generally fall into the moderate to high category.      /  ,     -          "
       The area within the glacial limit in northeastern Kansas is underlain by discontinuous
 glacial drift and loess.  The glacial deposits consist of a clay, silt,, or sand matrix with cobbles and
 boulders of igneous and metamorphic. rocks derived from as far away as the Lake Superior Region
 and southwestern Minnesota. The glacial deposits are discontinuous and till thickness varies
 markedly within the area, most likely because post-glacial erosion has, removed and redistributed
 significant amounts of drift. Because the loess in this area is likely derived from nearby glacial
 drift, and because glacial deposits are known to generate elevated indoor radon levels throughout
 the northern Great Plains, this area should be considered to have a moderate to locally high radon,
 potential.                                                "

 MISSOURI  ..   ' .  •             •                                              -..-,.."

       Missouri lies within the stable midcontinent area of the United States. The dominant
 geologic feature is the Ozark uplift in the southeastern part of the state which forms the Ozark
 Plateau Province. Precambrian crystalline rocks form the core of the uplift and crop out along its
 eastern side. Paleozoic sedimentary rocks dip away from this core in all directions. To the north,
 northwest, and west of the uplift these sedimentary sequences are folded into broad arches and
 sags. The Preeambrian core of the Ozark uplift is primarily granite and rhyolite. Much of this rock
 is slightly enriched in uranium. (2.5-5.0 ppm); The Preeambrian core is surrounded by Cambrian
 and Ordovician sandstone, dolostone, shale, cherty dolostone, chert, and limestone.
 Pennsylvanian sandstone,  shale and clay crop out in the north-central part of the uplift To the
 north and west of the uplift^ Mississippian and Pennsylvanian shale, limestone, sandstone, clay,
 coal, and fire clay occur. Silurian and Devonian sedimentary rocks crop out in central Missouri
 along the Missouri River and along the Mississippi River northeast of St Louis and in Cape
 Girardeau and Perry Counties south of St. Louis.   '..'.
       Uraniferous granites and rhyolites, and residuum developed on carbonate rocks in the
 Ozark Plateau Province are likely to have significant percentages of homes with indoor radon levels
 exceeding 4 pCi/L. The most likely areas are those where elevated eU values occur. Where
 structures, are sited on somewhat excessively drained soils in this area the radon potential is further
 increased. Extreme indoor radon levels may be expected where-structures are sited on uranium
                                            m-7    Reprinted from USGS Open-File Report 93-292-G

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occurrences and where the disturbed zone around a foundation is connected to solution openings in
carbonate rocks or to open zones in soil and bedrock caused by mine subsidence.
       The Ozark Plateau Province has a moderate overall radon potential.  Several areas of
somewhat excessively drained soils, scattered uranium occurrences, residual carbonate soils in
which uranium has been concentrated, and areas of karst may generate locally elevated indoor
radon levels in this area. The St Francois Mountains have high radon potential owing to elevated
levels of uranium in soils developed on granitic and volcanic rocks throughout these mountains and
substantial areas of somewhat excessively to excessively drained soils.
       The permeability of soils and subsoils in karst areas has been enhanced by solution
openings in and near carbonate pinnacles and by zones of solution collapse.  Where soils
developed on such carbonate rocks are thin, foundations may encounter open bedrock fractures in
the limestone. Karst underlies parts of the City and County of St Louis and may locally cause
elevated indoor radon levels.  Elevated eU and significant karst development occur in Perry and
Cape Girardeau Counties.  Structures sited on locally highly permeable karst soils with elevated eU
in these two counties will likely have elevated indoor radon levels. Broad karst areas have formed
by dissolution of carbonate rocks in the central and western Ozark Plateau, the southern Osage
Plain, and along the Mississippi River from Cape Girardeau County to Rails County. These
carbonate regions have overall moderate radon potential.  However, areas of intense karst
development, elevated uranium in residual soils developed on carbonate, and large areas of
somewhat excessively drained to excessively drained soils may cause locally high indoor radon
levels to occur.
       Several very thin, highly uraniferous (as much as 180 ppm), black, phosphatic shales
occur in the Devonian and Pennsylvanian sedimentary rock sequences in the unglaciated Osage
Plain of southwestern Missouri. Elevated indoor radon levels may be expected where the
foundations of structures intercept the thin Pennsylvanian uraniferous shales or the Chattanooga
Shale in the southwestern part of the state from Kansas City south to McDonald and Barry
Counties and in north-central Missouri in Boone, Randolph and Macon Counties, or where they
intercept well-drained alluvium derived from these rocks. Because these uraniferous  shales are so
thin, such circumstances are likely to be very site- or tract-specific; thus detailed geologic and soil
mapping will be necessary to outline areas of potential problems. Where these shales are jointed or
fractured or soils formed on them are somewhat excessively drained on Mllslopes, the radon
potential is further increased.  Residuum developed on limestones associated with these
uraniferous shales may also have elevated uranium levels and have significant radon potential. The
unglaciated Osage Plain province has a low overall radon potential; however, areas of thin soils
underlain by the uraniferous shales in this province have high radon potential with locally extreme
values possible.                           •
       Along the Missouri and Mississippi River valley floor, alluvial deposits (silt, sand, and
gravel) dominate. Loess deposits occur on the flanks of the river valleys in several areas and are
especially widespread in Platte, Buchanan, Holt, and. Atchison Counties along the Missouri River
north of Kansas City. Alluvium and loess along the upper Missouri River Valley upstream from
Kansas City seem to be producing elevated indoor radon levels that may be related to the somewhat
elevated uranium content of these materials and, possibly, to elevated radon emanation and
diffusion associated with well-drained loe'ss deposits. Detailed studies of indoor radon data in this
area would be necessary to determine more closely the origin of elevated indoor radon levels.
Thin, somewhat excessively drained soils developed on limestone that occur as" part of one soil
                                           m-8     Reprinted from USGS Open-File Report 93-292-G

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association in the southern suburbs of Kansas City may also be telated to elevated indoor radon
levels in Jackson County,
       The northernmost part of the Mississippi Embayment occupies the southeastern corner of
the state and forms the Coastal Plain Province, or southeastern lowlands. This area is underlain by
Tertiary and Quaternary alluvium. The Coastal Plain Province has a low radon potential overall.
Only one value exceeding 4 pCi/L is reported for a six-county area, and very poorly drained soils
are widespread.  However, some aeroradiometrie anomalies occur in this area, and some
excessively drained soils occur locally. Elevated indoor radonlevels may be associated with these
locales. Although elevated elJ occurs over some of the sedimentary rocks in this province, the
high soil moisture, the very poorly drained soils, and the low indoor radon values all point towards
low radon potential
       The surficial geology north of the Missouri River is dominated by glacial deposits covered .
with a thin veneer of loess; hpwever, several areas of residual soils developed on underlying
sedimentary rocks occur in the eastern and western parts of this region. Residual soils are those
soils formed by weathering of the material beneath the soil. These surficial deposits (both glacial'
deposits and residuum) are generally 50-200 feet thick, but they locally exceed 200 feet aJbhg the
northern edge of the state. The dissected till plain of northern Missouri has moderate overall radon
potential, although elevated indoor radon levels are common in areas of similar geology in adjacent
states, particularly Iowa, Nebraska (fig, 1), and Illinois. Except for counties along the  Missouri
River, the indoor radon data for the counties in the dissected till plain are sparse and appear to be
generally in the low to moderate range.    •  •                               .    ,. » ,

NEBRASKA                          ,            ,

       Rocks ranging in age from Pennsylvanian to Quaternary are exposed in Nebraska.
Pennsylvanian rocks are exposed in southeastern Nebraska and include limestones, shales, and
sandstones. Only some of the Upper Pennsylvanian strata are exposed in Nebraska; these rocks
are a repeated sequence of marine shales and limestones alternating with nonmarine sandstones and
shales, and thin coals.  Exposed Permian rocks consist of green, gray, and red shales, limestone,
and gypsum. Exposures of Pennsylvanian arid Permian rocks are generally limited to valley sides
along streams because much of the eastern part of the State is mantled with Pleistocene .glacial
deposits and loess. Black shales of Pennsylvanian age may constitute a significant radon source
where the shales are a source component of the glacial tills.
       Cretaceous rocks are exposed in' much  of eastern Nebraska, in parts of northern and
northwestern Nebraska, and along the Republican River Valley. Lower Cretaceous rocks consist
of sandstones, shales, and thin coals.  Upper Cretaceous rocks consist primarily of shale,   • ••   , >
limestone, and sandstone. The Upper Cretaceous Pierre Shale consists of gray, brown, and black
shales, with thin layers of bentohite, chalk, limestone, and sandstone. Although the permeability
of soils developed on the Pierre Shale is listed  as low, the shales contain numerous fractures and
partings and are likely to have sufficient permeability for radon transport during dry periods. The
stratigraphically lowest unit in the Pierre Shale is the Sharon Springs Member, a black shale of
widespread occurrence in Nebraska, South Dakota, Kansas, and Colorado. The Sharon Springs
Member is exposed in a relatively broad area along the Niobrara and Missouri Rivers from Keya
Paha to Cedar Counties and along the Republican River in southern Nebraska. -The gray-shale
units of the Pierre Shale, while not as urariiferous as the black shale of the Sharon Springs
Member, generally contain higher-than-average (i.e., >2.5 ppm) amounts of uraniura,and are
                                           m-9     Reprinted from USGS Open-File Report 93-292-G

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correlated with elevated indoor radon levels in several areas. Outcrops of the Pierre Shale in the
northwestern comer of Nebraska have the highest surface radioactivity in the State. Areas
underlain by Cretaceous rocks, particularly the Pierre Shale, have overall high radon potential.
       Tertiary rocks have the most widespread exposure in the State. The White River Group
consists of mudstone, siltstone, sandstone, and thin layers of volcanic ash, and is exposed in the
North and South Platte valleys and in northwestern Nebraska.  The Arikaree Group overlies the
White River Group and  consists of siltstone and sandstone. The Tertiary Ogallala Group covers
about two-thirds of the State.  It consists of sandstone, siltstone, gravel, sand, silt, clay, and thin
volcanic ash layers. The Ogallala is covered by the Sand Hills, an area of Quaternary windblown
sand deposits, in the north-central part of Nebraska.  Pre-Sand Hills sediments of Pliocene and
Quaternary age also overlie portions of the Ogallala in this area. The Ogallala, Arikaree, and White
River Groups all have high surface radioactivity (for purposes of this report, high radioactivity is
defined as greater than 2.5 ppm eU) and are known to host uranium deposits. Soils developed on
the Tertiary units have moderate permeability and generate moderate to locally high indoor radon.
The White River and Arikaree Groups have significant amounts of uranium-bearing volcanic glass
and may be somewhat more likely to generate elevated indoor radon concentrations. Areas
underlain by Tertiary sedimentary rocks have overall moderate radon potential. Some homes in
this area are likely to have high indoor radon levels, particularly those sited on uranium-bearing
parts  of the White River and Arikaree Groups in northwestern Nebraska.
      . Eastern Nebraska and southern Nebraska south of the Platte River are underlain by
Permian through Tertiary rocks mantled with Pleistocene glacial deposits of Pre-Dlinoian age and
loess. The glacial deposits  generally consist of a clay, silt, or sand matrix with pebbles and
cobbles of limestone, igneous rocks, and quartzite. Source material for the glacial deposits     :
includes locally-derived Permian and Perinsylvanian limestone and shale and Cretaceous sandstone
and shale, as well as lesser  amounts of sandstone, limestone, shale, and igneous and metamorphic
rocks from bedrock sources to the north and northeast. Of the source rocks underlying the glacial
deposits and those to the north and northeast, Cretaceous sandstones and shales, Pennsylvania*)
black shales, and Precambrian crystalline rocks all contain sufficient amounts of uranium-series
radionuclides (uranium and(or) radium) to generate radon at elevated levels.
       Loess covers most of the glacial deposits in eastern Nebraska as well as bedrock in the
south-central part of the State. Loess is a generally good radon source because it consists of silt
and clay-sized particles, which are more likely to be associated with radionuclides and have higher
emanation coefficients than larger sized particles, and it typically has moderate permeability.
Average indoor radon levels are consistently greater than 4 pCi/L in areas underlain by loess-
mantled glacial drift The majority of homes in the area underlain by loess-mantled bedrock in the
south-central .part of the State also have radon levels exceeding 4 pCi/L, but indoor radon levels
are likely to be more variable from house to house in south-central Nebraska, depending on the
distribution, thickness, or weathering extent of the loess.  Areas underlain by glacial drift and most
areas underlain by loess have overall high radon potential. The area mapped as loess between the
Platte River and the Sand Hills in the central part of the State has generally moderate radon
potential. Homes sited on thicker loess along the north side of the Platte River in Dawson and
Buffalo Counties may have locally high indoor radon levels. The Sand Hills have low surface
radioactivity and generally low radon potential.
                                           m-10    Reprinted from USGS Open-File Report 93-292-G

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   '   PRELIMINARY GEOLOGIC RADON POTENTIAL ASSESSMENT OF KANSAS
'..'••:      -       •        •   ';;-   by"   '' •"•••'.  '  '                  :
                                  R. Randall Schumann
                                 U.S. Geological Survey

INTRODUCTION                                                        '/•*•'

       Many of the rocks and soils in Kansas have the potential to generate levels of indoor radon
exceeding the U.S. Environmental Protection Agency's guideline of 4 pCi/L. In a survey ?of 2009
homes conducted during the winter of 1987-88 by the State of Kansas and the EPA, 25 percent of
the homes had indoor radon levels exceeding, this value. At the scale of this evaluation, all areas in
Kansas have moderate/variable or high geologic radon potential.      •
       This is a generalized assessment of geologic radon potential of rocks, soils, and surficial
deposits of Kansas. The scale of this assessment is such that it is inappropriate for use in
identifying the radon potential of small areas such as neighborhoods,  individual building sites, or
housing tracts. Any localized assessment of radon potential must be supplemented with additional
data and information from the locality. Within any area of a given radon potential ranking, there
are likely to be areas with higher or lower radon levels than characterized for the area as a whole.
Indoor radon levels, both high and low, can be quite localized, and there is no substitute for testing
individual homes. Elevated levels of indoor radon have been .found in every-sfate, and EPA
-recommends that all homes be tested. For more information on radon, the reader is urged to
consult the local or State radon program or EPA regional office. More .detailed information on state
'or local geology may be obtained from the'State geological survey. Addresses and phone numbers
for these agencies are listed in chapter 1 of this booklet.

PHYSIOGRAPHIC AND GEOGRAPHIC SETTING

       Kansas lies within .the Great Plains and Central Lowlands physiographic provinces Of the
United States. Within the State the landscape is subdivided into  11 physiographic areas (fig. 1 j.
The extreme southeastern comer of the State is part of the Ozark Plateau, in which beds of
limestone and chert form hills similar to those in Missouri and Arkansas. The Cherokee Lowlands
lie adjacent to the Ozark Plateau in southeastern Kansas. This area is relatively flat and poorly
drained because it is underlain by easily credible sandstones and shales. The Cherokee Lowlands
is a major coal-producing area. Underground mining for coal and metals occurred in the Cherokee
Lowlands and Ozark Plateau regions (Wilson, 1984). The Osage Cuestas (fig. 1) is an area of
parallel ridges, with a steep escarpment on their east sides and a gentle slope on their west sides,  ,
formed by gently dipping, alternating resistant and soft rocks. The Chautauqua Hills extend   ;
northward from the southern border of the State into the Osage Cuestas region.  The Chautauqua
Hills are rolling uplands capped by sandstones and limestones (Steeples and Buchanan, 1983;  .
Wilson, 1984).  To the west of the Chautauqua Hills are the Flint Hills", grassy uplands formed on
limestone and chert with intervening lowlands underlain by shales. Because chert is more resistant
to erosion than limestone, the Flint Hills are significantly higher than  the surrounding landscape
(Wilson, 1984),  The Wellington-McPherson Lowlands lie west  of, and adjacent to, the Flint Hills
(fig. 1). The Red Hills, along the central southern border of Kansas, are composed  of red shale
and siltstone, called "red beds", capped by gray gypsum and dolomite, and are characterized by
butte-and-mesa topography (Wilson,. 1984). In Meade and Clark Counties, on the western border
                                          IV-1 .   Reprinted from USGS Open-File Report.93-292-G

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PIWI»I	_J ou«
        t    •• \    .  «:
      .:;i: ";„".!t  • '.-r

t~,  ^H^-pKS

       ]•;    j;.-"]
                                                                                  so
                                      ARKANSAS RIVER LOWLANDS







                                     ' WELLINGTON-MCPHERSON LOWLANDS






                                      FLINT HILLS UPLANDS






                                      CHAUTAUQUA HILLS

                                                        i



                                      CHEROKEE LOWLANDS






                                      O2ARK PLATEAU
                                                                                               100 miles
   75           150 kilometers





OSAGE CUESTAS






GLACIATED REGION






HIGH PLAINS






RED HILLS






SMOKY HILLS
                       Figure 1. Physiographic regions of Kansas (from Wilson, 1984).

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  of the Red Hills, sinkholes have formed from dissolution of the salt and gypsum beds underlying
  the area.        ,    ....''.           !
        The northeastern part of Kansas is a distinctive MEy region formed on Pleistocene glacial
  deposits, called the glaciated region (fig. 1). In this area the rolling hills are covered by scattered
  cobbles and boulders of crystalline rocks such as red Preeambrian quartzite from southern
  Minnesota and northern Iowa (Wilson, 1984). The Smoky Hills occupy much of north-central
.  Kansas (fig. 1).  The eastern part of the Smoky Hills is characterized by sandstone hills and buttes '
  that rise sharply above the surrounding plains. The uplands in the middle part of the Smoky HiMs
  region are underlain by limestones and chalky shales.  This is the "Fencepost Limestone country",
  in which beds of one-foot-thick limestone were used for masonry and for fenceposts on rangeland
  (Wilson, 1984). The western part of the Smoky Hills region is developed on thick chalks of the
  Cretaceous Niobrara Formation, which form hills and buttes with a badlands appearance. Most of
  the western part of the State is in the High Plains region, a subset of the High Plains Province that
  begins at the foot of the Rocky Mountains and covers much of the central interior of the United
  States from Texas to the Dakotas.  The Arkansas River Lowlands (fig. 1) are formed in the broad,
  flat valley of the Arkansas River.  Much of the valley and surrounding plains are covered by dunes
  of windblown sand. Extensive windblown silt deposits, called loess, cover large parts of the
  Kansas landscape as well.                                                                <•
        Kansas is divided into 105 counties (fig. 2). The population of Kansas is largely rural,
  with farming and livestock as major industries. Most counties have populations less than 10,000
  (fig. 3); counties with more than 100,000 inhabitants are those with large urban-centers, including
!  Johnson and Wyandotte (Kansas City), Shawnee-(Topeka), and Sedgewick (Wichita) (fig. 3).

  GEOLOGY                                                                         ,•  ,

     ,,  Almost all of the bedrock exposed at the surface in Kansas consists of sedimentary units
  ranging in age from Mississippian to Quaternary (fig. 4) (Ross, 1991). 'Igneous rocks native to
  Kansas and exposed at the surface are small localized exposures of Cretaceous larnproite in
  Woodson County (Wagner, 1954; Cullers and others, 1985) and Cretaceous kimberlite in'Riley
  County (Brookins, 1970), Sedimentary rocks of Mississippian age underlie the extreme
  southeastern corner of the State (fig. 4). They consist primarily of limestones but also include
  shale, dolomite,.chert, sandstone, and siltstone. Pennsylvanian rocks underlie approximately the
  eastern one-quarter of the State. They consist of an alternating sequence of marine and nonmarine
  shale, limestone, sandstone, and coal, with lesser amounts of chert and conglomerate.  The shales
  range from green and gray (low organic content) to black (organic rich). Permian rocks are
  exposed in east-qentral-and southern Kansas (fig. 4) and consist of limestone, shale, gypsum,
  anhydrite, chert, siltstone, and dolomite.  Red sandstone and shale (red beds) of Permian age
  underlie the Red Hills along the southern border of Kansas (figs. 1,4).  Triassic rocks are exposed
  at the surface only in a small area in Morton County and consist chiefly of sandstone and shale.
  Jurassic rocks are not exposed at the surface in Kansas.  Cretaceous sedimentary rocks underlie
  much of north-central and central Kansas (fig. 4), and consist of green, gray, and black shale,
  sandstone, siltstone, limestone, chalk, and chalky shale.  A discontinuous,layer of loess
  (windblown silt) of varying thickness covers the Cretaceous rocks in many areas, particularly in
  •the western part of the Cretaceous outcrop area. Tertiary rocks cover much  of western Kansas,
  though they are covered by loess deposits in many areas' (fig. 4). Tertiary rocks consist of
                                             IV-3    Reprinted from USGS Open-File.Report 93-292-G

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Figure 2. Kansas counties.

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 POPULATION (1990)

0  0 to 10000 •
0  10001 to 25000
EH  250011050000
H  50001 to 100000
•  100001 to 403662   '
                   Figure 3. Population of counties in Kansas .(1990 U.S. Census data).

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                                                                              ij^:j.|i	:|::::::i

                                                                         |::::} ».*":: :rJsiJr:l Ii»Trr]



                                                                         S^KiiilisiuiiiiiiiiyJ
                                                                          • • • • ;i;«ooosw' ''•«««" *" i *w*.,,
                                                                          	;• r • yigneous;;;:;;: j

                                                                          H^ilLiil^^h:::::]
     Quaternary glacial deposits
                                               Jurassic
    Permian
                                 Silurian-Devonian
      Cambrian-Ordovician
 ••;«*, Tertiary  and  Quaternary
      Cretaceous
;::f| Pennsylvanian





    Mississippian
\'/////,  Precambrian
                                        SO
                                             SO          100  mi

                                             i	    	i
    100 km
Figure 4. Generalized geologic map of Kansas (modified from Kansas Geological Survey)..

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ERAS
GENOZOIC
MESOZOIC
PALEOZOIC
PERIODS EPOCHS
HOLOCENE
PLEISTOCENE
PUOCENE ,
MIOCENE
TERTIARY . OUQOCENE
EOCENE
' ~ .PALEOCEN6
CRETACEOUS
JURASSIC '
TRIASSIC .
". PERMIAN . •
PENNSYLVANIAN
MISSISSIPP1AN
DEVONIAN
SILURIAN
ORDOV1CIAN /
CAMBRIAN
F*RECAMBRIAN
EST. LENGTH
IN. YEARS
10,000+
1,990,000
3,000,000
r 19,000,000
14,000,000
17,000,000
8,ooo;ooo
i
- 75,000,000 .
67,000,000
35,000,000
.50,000,000
f
40,000,000
30,000,000
• 50,000,000 .
25,000,000
65,000,000
70,000,000
1,930,000^000
1,100.000,000 +
TYPE OF ROCK IN KANSAS
Glacial drift; river silt, sand, and
(loess); volcanic ash.

River silt, sand, gravel, fresh-
water limestone; volcanic ash; •
bentoriite; diatomaceous marl;
opaline sandstone. •

Limestone, chalk, chalky shale,
dark shale, varicolored clay, sand-
stone, conglomerate. Outcropping
igneous rock.
Sandstones and shales, chiefly
subsurface Siltstohe chert'*a*3d
gypsum.
Limestone, shale, evaporites (salt,
gypsum, anhydrite), red sand-
stone; chert, sittstone, dolomite,
and red beds.
Alternating marine and nonmarine
shale, limestone, sandstone, coal;
. chert and conglomerate.
Limestone, shale, dolomite, chert,
oolites, sandstone, and siltstone. • "
Subsurface oniy. Limestone, pre-
dominantly black shale; sand-
stone.
Subsurface only. Limestone.
' Subsurface only. Dolomite, sandr. «
stone, , ' ' '•
Subsurface only. Dolomite, sand-
stone, limestone, and shale.
Subsurface only. Granite, other
igneous rocks, and metamorphic
rocks, ',
                                                                               en

                                                                               in


                                                                               •z.
                                                                               'O
"Figure"4 (continued) Kansas strati'graphic chart (modified from Kansas Geological Survey).

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nonmarine sandstone, siltstone, and shale; volcanic ash deposits; and unconsolidated gravel, sand,
silt, and clay.
       Pre-Dlinoian (Pleistocene) glacial drift covers bedrock in the northeastern part of the State
(fig. 4). The glacial deposits consist of a clay, silt, or sand matrix with cobbles and boulders of
igneous and metamorphic rocks derived from as far away as the Lake Superior Region and
southwestern Minnesota (Port, 1987). The glacial deposits are discontinuous and till thickness
varies markedly within the area, most likely because post-glacial erosion has removed and
redistributed significant amounts of drift (Doit, 1987),  Loess, windblown silt deposits ranging
from 0 to more than 30  meters in thickness, covers as much as 65 percent of the surface of Kansas
(Welch and Hale, 1987) and is thickest and most extensive in the western and north-central parts of
the State and in proximity to glacial deposits in the northeastern corner of the State (fig. 5).
Possible sources for the loess include: (1) glacial outwash, (2) sand dunes in the Arkansas and
Cimarron River valleys (fig. 4) or elsewhere (such as the Sand Hills of Nebraska), and (3) erosion
by wind and rivers of the Tertiary Ogallala Formation (Welch and Hale, 1987).
       Uranium in above-average concentrations (according to Carrnichael (1989), average crustal
abundance of uranium is 2.5 ppm) is found in a number of rocks in Kansas. Uranium is found in
phosphatic black shales of Pennsylvanian age in eastern Kansas. Uranium contents in- the black
shales range from about 15 ppm to 100 ppm; concentrations of as much as 350 ppm uranium are
found in phosphate nodules within the shales (Berendsen and others, 1988). Pennsylvanian
phosphatic black shales exposed in eastern Kansas include the Heebner, Eudora, Muncie  Creek,
Quindaro, Stark, Hushpuckney, Anna, LMe Osage, and Excello Shale Members, the Pleasanton
Group, and shales above the Bevier and Croweburg coals (Berendsen and others, 1988; Coveney
and others, 1988). The  Cretaceous Sharon Springs Member, a black shale unit at the base of the
Pierre Shale, contains from 10 to 40 ppm uranium in western Kansas (Landis, 1959). Uranium is
associated with silica-cemented layers in the Tertiary Ogallala Formation in several localities in
western Kansas.  The uranium content of the rocks appears to correlate directly with the amount of
silica cementation of the rocks, with as much as 125 ppm uranium in the most intensely silicified
layers (Berendsen and Hathaway, 1981; Berendsen and others, 1988). A continuously silicified
area of the Ogallala Formation about 10 miles long and 1.5 miles wide is located in Meade and
Clark Counties (Berendsen and Hathaway, 1981). The source of the uranium and silica in the
Ogallala is postulated to be volcanic ash that is mixed in with the sediments throughout their '
outcrop area (Carey and others, 1952;  James, 1977; Zielinski, 1983). Eighteen samples of
volcanic ash from Tertiary and younger rocks in Kansas yielded from 3.9 to 9.1 ppm uranium
(James, 1977). Other uranium occurrences have been found in Mmberlite pipes in Riley County,  •
in the Cretaceous Dakota Sandstone in Ellsworth County, in the Cretaceous Smoky Hill Member
of the Niobrara Chalk in a large area of Gove County, and in Tertiary volcanic ash outcrops in
Meade and Clark Counties (Zeller and others, 1976).
       Anomalous concentrations of uranium in ground water were found in wells producing from
the Permian Nippewalla Group, Cretaceous Kiowa-Cheyenne Sandstones, and' Quaternary
alluvium (Berendsen and others, 1988); anomalous uranium concentrations in ground water (from
2 to 172 parts per billion uranium) have also been noted in wells producing from the Ogallala
aquifer and Arkansas River alluvium in western Kansas (Berendsen and Hathaway, 1981).
Ground water in  southeastern Kansas is generally low in uranium but contains elevated
concentrations of 226Ra (Macfarlane, 1981), suggesting that these waters may also contain high
levels of dissolved radon in some areas.
                                          IV-8    Reprinted from USGS Open-File Report 93-292-G

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          &SBKM&I i?Sv " »•!«.»  cif ^- — N«J '*'< ' *'•«*'
                      .
         i-iaLaei Ul j S. _ 3-^. _^
                       Loess  from- Geologic
                       Mop of Konsds

                       Old alluvial  soils  -  .
                       with a loess component

                       Loess  oVerlain  by dune  sand
Loess mantled areas  not
depicted on,Geologic  Map
of Kansas
Sedimentary rock,  old
and/or  recent alluvium,
Or dune sand
                                                                   0
        50
100 mi
                                                                   0
          100 km
Figure 5. Map showing distribution of loess in Kansas (from Welch and Hale, 1987). Loess in the area marked "Loess mantled areas
        not shown on Geologic Map of Kansas" is generally less than 2 feet thick;

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SOILS

       Most soils In Kansas belong to the suborders Ustolls and Udolls (Bidwell and McBee,
1973). If Kansas is vertically divided into quarters, the western quarter of the State is covered by
Aridic Ustolls, the west-central quarter is covered by Typic Ustolls, the east-central quarter is
covered by Udic Ustolls, and the eastern quarter is covered by Typic Udolls. Aridic Ustolls are
deep, grayish-brown silt loams and sandy loams with a layer of calcium carbonate accumulation at
approximately one meter (Bidwell and McBee, 1973), These soils have generally low to moderate,
permeability (fig. 6).  The western part of the State that is covered by Aridic Ustolls receives
508 mm (20 in) or less of precipitation annually (Steeples and Buchanan, 1983). Typic Ustolls,
which cover the west-central quarter of Kansas, are deep and moderately deep, dark grayish-
brown to reddish-brown silt loams and clays with calcium carbonate accumulations at 1-2 m depth
(Bidwell and McBee, 1973) and generally low permeability (fig. 6). This part of the State receives
508-635 mm (20-25 in) of precipitation annually.  Approximately the east-central quarter of the
State is covered by Udic Udolls, shallow to deep, grayish-brown silt loams and clay loams with
secondary carbonate horizons at more than 1 rn depth (Bidwell and McBee, 1973). These soils
have tew to moderate permeability (fig. 6), and this part of the State receives between 635 mm
(25 in) and 889 mm (35 in) of precipitation annually (Steeples and Buchanan, 1983). Eastern
Kansas receives from 889 mm (35 in) to more than 1000 mm (40 in) of precipitation annually and
is covered by Typic Udolls, black and dark brown silt loams to clay loams with secondary
carbonate accumulations at depths exceeding 1.5 m. These soils have generally low permeability
(fig. 6) and many of the soils in eastern Kansas have seasonally high water tables (Olson, 1974).
Soils developed on alluvium in river valleys, most notably that of the Arkansas River, are sand and.
sandy loams with high permeability (fig. 6). The extreme southeastern corner of Kansas is  -
covered by Typic Udults, deep, brown eherty silt loams with secondary calcium carbonate
horizons at more than 1.5 m depth (Bidwell and McBee, 1973) and high permeability (fig. 6).

INDOOR RADON DATA

       Screening indoor radon data from 2009 homes sampled in the State/EPA Residential Radon
Survey conducted in Kansas during the winter of 1987-88 are shown in figure 7 and listed in Table
1. Data are only shown in figure 7 for those counties with 5 or more data values. The maximum
value recorded in the survey was 48 pCi/L in Marshall County. Except for counties in the Kansas
City, Topeka, and Wichita areas, most counties in the survey are represented by 20 or fewer
indoor radon measurements (fig. 7); 19 counties have more than 20 measurements. Given the
relatively sparse distribution of data, observations concerning the distribution of indoor radon
concentrations based on these data should not be considered conclusive statements on indoor radon
distributions within Kansas, but they are useful in establishing geologically-related trends.
       Most counties in southeastern and south-central Kansas have low (0-2 pQ/L)  to moderate
(2-4 pCi/L) indoor radon averages. Counties in northeastern Kansas have moderate to high
(> 4 pC5/L) indoor radon averages (fig. 7). Berendsen and  others (1988) report that elevated
indoor radon levels were found in the Kansas City area and in Chanute in a survey of indoor radon
levels by the Kansas Department of Health and Environment Most of the counties in north-central
and central Kansas have high indoor radon averages in the State/EPA survey, and western Kansas
has an approximately equal mixture of counties with moderate and high indoor radon  averages
(fig. 7). The highest maximum radon readings occur in northeastern and central  Kansas (Table 1).


                                         'lV-10    Reprinted from USGS Open-File Report 93-292-G

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                  SOIL PERMEABILITY
                  lllLOW(<0.6ln/hr)
                  VTA MO DERATE (0.6-6.0 irVhr)
                  r~lHIGH(>6.0liVhrt
* miles
             100
Figure 6.  Generalized soil permeability map of Kansas (data from Olson, 1974; map'units from Bidwell and McBee, 1973).

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                                                                  Bsmt. & 1st Floor Rn
                                                                     %>4pCi/L

                                                                        OtolO
                                                                        11 to 2.0
                                                                        21 to 40
                                                                        41 ta 60
                                                                        61 to 80
                                                                   1 I  81 to 100,
                                                                12 '   I  Missing Data
                                                                        or < 5 measurements
                                                                     Bsmt. & 1st Floor Rn
                                                                 Average Concentration (pCi/L)
                                                                        0.0 to 1.9
                                                                        2.0 to 4.0
                                                                        4.1 to 9.0
                                                                        Missing Data
                                                                         or < 5 measurements
Figure 7.  Screening indoor radon data from the EPA/State Residential Radon Survey of Kansas,
1987-88, for counties with 5 or more measurements. Data are from 2-7 day charcoal canister
tests. Histograms in map legends show the number of counties in each category. The number of
samples in each county (See Table 1) may not be sufficient to statistically characterize the radon
levels of the counties, but they do suggest general trends.  Unequal category intervals were
chosen to provide reference to decision and action levels.

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TABLE 1.  Screening indoor radon data from the EPA/State Residential Radon Survey of
Kansas conducted during!986-87. Data represent 2-7 day charcoal canister measurements
from the lowest level of each home tested.
COUNTY
ALLEN
ANDERSON
ATCmSON
BARBER
BARTON
BOURBON
BROWN
BUTLER
CHASE
CHAUTAUQUA
CHEROKEE
CHEYENNE
CLARK
CLAY
CLOUD
COEFEY
COMANCHE
COWLEY
CRAWFORD
DECATUR
DICKINSON
DONIPHAN
DOUGLAS
EDWARDS
ELK
ELLIS
ELLSWORTH
FINNEY
FORD
FRANKLIN
GEARY
GOVE
GRAHAM
GRANT
GRAY
GREELEY
GREENWOOD
HAMILTON
HARPER
HARVEY
HASKELL
NO. OF
MEAS.
20
9
10
9
24
15
7
29
10
6
20
11
6
7
11
4
' 5'
29
46
4
15
- 5
36
4
3
26
17
15
14
• 22
8
8
6
, 8
5
5
• 5
8
1
13
2
MEAN
0.6
0.8
2.9
1.9
3.4
1.7
2.4
1.6
2.0
0.8
0,9
3.9
4.6
9.0
4.2
2.6
2.0
1.9
1.1
3.1
4.1
3.0
2.6
3.1
0.7
3.6
5.9
2.0
5.4
1.6
6.6
4.4
4.0
4.2
6.2
2.9
1.9
4.7
1.6
3.0
3.4
GEOM.
MEAN
0.3
0.6
2.3
1.6
2.0
1.2
2.1
0.9
1.5
0.5
1 0.5
3.1
3.7
3.7
3.1
1.7
1.0
1.6
0.7
2.4
3.2
2.6
1.6
2.5
0.7
3.2
4.5
1.9
4.2
1.1
5.2
3.7
2.8
3.4
5.8
2.6
1.2
3.4
' 1.4
2.3
3.2
MEDIAN
0.4
0.7
2.3
1.7
1.9
1.3
2.5
1.1
1.3
. 0.4
0.4
2.9
' 4.4
2.4
3.1
2.5
1.0
1.6
0.8
2.4
3.3
3.2
2.0
2.9
0.6
3.6
5.7
1.7
4.3
1.0
5.2
3.7
3.1
3.2
6.4
3.0
1.1
2.8
1.0
2.2
. -3,4
STD.
DEV.
0.6
0.6
2.1
1.0
4.7
1.3
1.2
1.7
1.9
1.0
1.1
3.2
3.0
12.0
3.2
, 1.9
2.9
1.1
1.2
2.4
3.8
1.4
2.5
2.0
0.3
1.8
3.7
0.9
3.8
- 1.5
5.6
2.5
3.2
3.1
2.5
' 1.4
1.9
4.5
1.1
•2.5
1.7
MAXIMUM
2.4
2.0
6.9
.3.7
23.0
4.3
4.0
7.6
6.7
2.7
4.0
12.6
9.3
28.1
.9.5
4.9
7.1
4.4
6.0
6.4
16.5
4.5
12.9
5.6
1.0
8.6
13.2
4.7
12.2
5.9
19.3
8.2
9.2
10.1
8.8
4.9
4.9
14.8
3:7
9.9
4.6
%>4pCi/L
0
0
20
"' 0
21
7
0
7
10
0
0
36
"'< . 50
29
36
25
20
7.
. -• 4
25
' -V '33
20 ;
. 19
25
0,
38
65
. 7
50
- ' • 5
63
50
33
50
80
20
20
38
0
n
50,,
%>20pCi/L
0
0
0
0
4
0
0
0
0
0
0
0
0
29
0
0
0
0
0
0
0
0
0
0
0
0
0
/o
0
0
0
0
0,
0
0
0
0
0
0
0
0

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TABLE 1 (continued).  Screening indoor radon data for Kansas.
COUNTY
HODGEMAN
JACKSON
JEFFERSON
JEWELL
JOHNSON
KEARNY
K1NQMAN
KIOWA
LABETTE
LANE
LEAVENWORTH
LINCOLN .
LINN
LOGAN
LYON
MARION
MARSHALL
MCPHERSON
MEADE
MIAMI
MITCHELL
MONTGOMERY
MORRIS
MORTON
NEMAHA
NEOSHO
NESS
NORTON
OSAGE
OSBORNE
OTTAWA
PAWNEE
PHILLIPS
POTTAWATOMIE
PRATT
RAWLINS
RENO
REPUBLIC
RICE
RILEY
ROOKS
RUSH
RUSSELL
NO. OF
MEAS.
6
8
10
8
339
9
7
8
17
3
28
7
8
8
17
2
12
21
12
22
8
41
5
8
9
11
19
10
12
9
6
2
27
11
9
10
45
8
7
32
10
8
8
MEAN
3.5
1.1
4.0
3.4
3.8
3.0
1.3
5.2
1.9
2.9
2.5
2.0
1.4
5.3
1.2
3.2
8.5
4.6
4.9
1.8
6.7
0.7
6.3
2.5
3.3
1.3
4.8
4.8
2.5
7,0
3.7
8.9
4.5
3,6
.2.0
2.7
2.2
'2.8
2.5
4.6
3.9
5.1
4.5
GEOM.
MEAN
2.7
1.0
2.7
2.6
*2.5
2.4
0.8
3.7
0.5
1.9
1.6
1.7
0.9
4.7
0.9
3.2
3.7
3.6
3.3
1.4
4.8
0.5
2.3
1.7
2.2
1.0.
3.1
4.2
1.8
5.6
1.5
7.8
. 3.5
1.8
1.9
2.2
1.4
2.2
1.9
2.4
2.9
3.6
3.9
MEDIAN
3.6
1.0
4.3
3.3
2.6
" 3.4
1.2
4.2
0.4
1.6
2.0
.1.2
1.1
6.1
0.7
3.2
3.9
3.7
3.3
1.5
5.4
0.4
2.6
1.4
2.9
0.9
3.8.
4.2
1.6
7.7
1.2
8.9
3.9
1.4
1.7
2.3
1.7
2.8
1.8
2.5
3.8
4.2
3.4
STD.
DEV.
2.1
0.6
2.7
2.4
4.1
1.7
1.2
4.8
4.6
3.1
2.0
1.2
1.1
2.4
1.0
0.1
13.4
3.6
4.3
1.3
5.2
0.7
9.8
2.4
3.0
0.9
5.4
2.4
2.5
4.6
6.4
6.1
2.9
4.9
0.8
1.7
2.2
1.9
2.4
5.6
2.7
4.8
2.7
MAXIMUM
6.7
2.1
7.5
7.4
32.0
5.6
3.0
16.2
19.5
6.4
7.3
3.5
3.1
8.7
3.6
3.3
48.0
17.0
13.4
5.6
16.1
3.5
23.7
7.8
9.8
3.2
24.6
8.6
9.6
16.1
16.6
13.2
13.5
15.3
3.5
5.8
11.7
6.8
7.8
25.5
9.3
15.6
10.0
%>4pCi/L
33
0
60
50
29
33
0
50
6
33
18
0
0
63
0
0
50
43
50
5
63
0
20
13
33
0
47
50
17
67
17
100
48
27
0
20
7
13
14
41
40
50
38
%>20 pCI/L
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
.8
0
0
0.
0
0
20
0
0
0
5
0
0
0
0
0
0
0
0
0
0
0
0
3
0
0
0

-------
TABLE 1 (continued). Screening indoor radon data for Kansas.
COUNTY
SALINE
SCOTT
SEDGWICK
SEWARD
SHAWNEE
SHERIBAN
SHERMAN
SMITH
STAFFORD
STANTON
STEVENS
SUMNER
THOMAS
TREGO
WABAUNSEE
WALLACE
WASHINGTON
WICHITA
WILSON
WOODSON
WYANDOTTE
NO. OF
MEAS.
32
21
217
12
109
8
8
7'
7
4
3
10
14
14
7
3
7
3
15
17
110
MEAN
4.8
5.8
2.1
2.9
2.9
4.6
4.0
4.6
3.8
5.7
13.0
1.5
3.6
3.8
1.9
'4.8
3.4
5.5
1.4
0.7
3.6
GEOM.
MEAN
3.4
4.9
1.6
2.6
1.9
3.3
3.2
4.1
3.0
5.0
6.4
1.1
3.0
3.1
1.7
4.8
,2.4
^ 5.4
0.8
0.5
2.5
MEDIAN
3.5
5.4
1.6
2.7
' , 2.1
3.0
2.8
4.4
3.7
6.5
9.1
1.7
3.0
3.1
1.7
4.7
2.7
-5.0
0.5
0.5
3.1
STD.
DEV.
4.5
3.2
1.7
1.2
3.1
4.0
2.9
2.2
2.4
2.8
14.4
1.0
2.3
2.5
1.0
0.4
2.4
1.1
2.1
0.6
3.1
MAXIMtFM
20.7
15.7
8.0
5.6
19.7
12.2
9.3
7.5
7.0
7,9
29.0
3.2
9.9
9.1
3.4
5.2
7,0
6.8
7:7
2.1
16.3
%>4 pCi/L
38
81
12
8
22
38
*!*»38
57
43
75
67
0
36
.... 43
0
-" 100
43
100
7
0
35
%>20 pCi/L
i 	 3
0
0
-Q
0
0
0
0
0
0
33
0
0
0
0
0
0
0
,0
0
0

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GEOLOGIC RADQN POTENTIAL                              •

       An examination of geologic (fig, 4), soil (fig. 6), indoor radon (fig. 7), and radioactivity
(fig. 8) data allows identification of rocks and sediments in Kansas that have the potential to
generate indoor radon levels exceeding the EPA's 4 pCi/L guideline. A northeast-southwest
trending line of high radioactivity (for this evaluation, "high" is defined as greater than 2.5 ppm
equivalent uranium [eU]) in southeastern Kansas (fig. 8) is likely associated with Pennsylvanian
black shales.  However, most of the Pennsylvanian black shale outcrops are thin, usually no more
than a few meters thick, so they are too narrow to detect on the aerial radioactivity map, which has .
a grid cell, or "pixel", size of about 2.5 km (1.6 mi) (Duval and others, 1989). Permian
sedimentary rocks comprising the Chautauqua Hills (fig. 1) have a low (<1.5 ppm eU)
radioactivity signature (fig. 8). With these exceptions, Pennsylvanian and Permian rocks in the
State have an overall intermediate (1.0-2.5 ppm eU) radioactivity signature. Because the majority
of Pennsylvanian and Permian rocks have relatively low uranium contents, and because soils
developed on these rocks have generally low permeability and many are subject to seasonally high
water tables, these rocks have a generally low radon potential. However, homes situated on
Pennsylvanian and Permian carbonate rocks (limestones and dolomites) may have locally elevated
indoor radon levels if the limestones have developed clayey residual soils and(or) if solution
features (karst topography), are present in the area. Although the carbonate rocks themselves are
generally low in uranium and radium, the soils developed on these rocks are typically derived from
the residual materials of dissolution of the CaCOs that makes up the majority of the rock. When
the CaCOs has been dissolved away, the soils are enriched in the remaining impurities,
predominantly base metals, including uranium. Carbonates also form karst topography,
characterized by solution cavities, sinkholes, and caves, which increase the overall permeability of.
the rocks in these areas and may induce or enhance convective flow of radon. Homes sited on
Pennsylvanian black shale units are likely subject to locally high indoor radon levels. This appears
to be the case in the Kansas City area, part of which is underlain by black shales (fig. 7> Berendsen
and others, 1988).
       Some elevated indoor radon levels in the northern part of the Permian  outcrop area,
specifically in Marshall,  Clay, Riley, Geary, and Dickinson Counties, may be related to faults and
fractures of the Mid-Continent Rift and Nemaha Uplift (Berendsen and others, 1988). The Mid-
Continent Rift (MCR) zone is an area of NNE-SSW-trending faults and fractures which were most
active during Late Mississippian to Early Pennsylvanian time (Berendsen and others, 1989), but
have been active during modern times, as evidenced by modern microearthquakes (Wilson, 1979).
Many of the subsurface faults reach and displace the surface sedimentary rock cover, and the
density and spacing of faults and fractures within the rift zone is relatively high (Berendsen and   •
Blair, 1986; Berendsen and others, 1989). Soil-gas helium surveys conducted jointly by the
Kansas Geological Survey and the U.S. Geological Survey indicate that faults and fractures within
the MCR are areas of high permeability and they show evidence that fluids and gases are able to
migrate upward from deeper source rocks (G.M. Reimer, unpublished report, 1985).  Fault and
shear zones are commonly areas of locally elevated radon because these zones typically have higher
permeability than the surrounding rocks, because they are preferred zones of uranium
mineralization, and because they are pathways for potentially uranium-, radium-, and(or) radon-.
bearing fluids and gases  to migrate (Gundersen, 1991).
                                          IV-16    Reprinted from USGS Open-File Report 93-292-G

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               0^ °f ^fsan iafter D^?! md others' 1989>- Contour Hnes at L5 ^ 2.5 ppm equivalent uranium (ell).
Pixels shaded from 0 to 6.0 ppm eU at 0.5 ppm eU increments; darker pixels have lower eU values; white indicates no data.

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       Cretaceous rocks in northern, central, northwestern, and west-central Kansas include
sandstones, shales, and local volcanic ash deposits that contain sufficient uranium to generate
elevated indoor radon levels. The Cretaceous rocks overall have a moderate (1.5-2.5 ppm elJ)
radioactivity signature (fig. 8). Some areas of higher radioactivity may be masked by surface
accumulations of loess,  A few scattered radioactivity anomalies in western and central Kansas
(fig. 8) may be associated with outcrops of the Sharon Springs Member of the Pierre Shale or with
alluvium in major drainages.  Soils developed on Cretaceous rocks have low to moderate
permeability (fig. 6), but the shale-derived soils with low permeability to water likely have
moderate permeability to soil gas when they are dry due to desiccation cracks (Schumann and
others, 1989,1991).  Areas underlain by these rocks have an overall high radon potential. Areas
underlain by the Tertiary Ogallala Formation have a moderate radioactivity signature and a
moderate to high radon potential. Again, the radioactivity of the bedrock may be masked in some
areas by surflcial loess deposits.                                  .
       Although loess in many cases has lower radioactivity than underlying bedrock units, it
typically is able to generate as much or more radon than the bedrock it covers. Radon potential of
loess-mantled areas depends on the thickness and source of the loess. In areas of very thin loess
cover, the radon potential of the underlying bedrock is significant, and the loess both generates
radon and transmits radon from the underlying bedrock, whereas if the loess is more than 7-10 m
thick, it is probably the sole radon source for homes in the area.  Because several sources are
postulated for loess in Kansas, and loess thickness in the State has not yet been mapped in detail
(Welch and Hale, 1987), it is difficult to make definitive statements  concerning the radon potential
of loess-mantled areas in Kansas. However, similar loess deposits  in southern Nebraska generate
widespread elevated indoor radon levels (see the Nebraska radon potential chapter in this volume).
Loess-covered areas underlain by Cretaceous and Tertiary bedrock appear to have variably
moderate to high radon potential across the State, and locally elevated indoor radon levels may be
expected anywhere within areas underlain by these units. Areas underlain by loess-covered
Pennsylvanian and Permian rocks appear to generate moderate to locally elevated indoor radon
levels.
       The area within the glacial limit in northeastern Kansas is underlain by discontinuous
glacial drift and loess. Because the loess in this area is likely derived from nearby glacial drift, and
because glacial deposits are known to generate elevated indoor radon levels throughout the
northern Great Plains, this area should be considered to have a moderate to locally high radon
potential. Areas of windblown sand in the Arkansas and Cimarron River valleys have a low
radiometric signature (fig. 8). The sand dunes themselves have low uranium contents and low
radon potential, but few homes are built directly on the sand dunes.  The dune sands are intermixed
with loess in parts of the'Arkansas and Cimarron valleys, and the radon potential may be related to
the relative proportions of sand, loess, and bedrock within these areas.  Areas underlain by dune
sand are expected to have lower radon levels, areas with considerable loess content are expected to
have moderate to locally elevated radon levels.  Where sand or loess is thin or absent, the radon
levels in homes on Tertiary or Cretaceous bedrock are also expected to generally fall into the
moderate to high category.
                                           IV-18    Reprinted from USGS Open-File Report 93-292-G

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SUMMARY'; ."      .        '_     '     • ' .  -" -:  . v  '            ,

       For the purposes of this assessment, Kansas is divided into six geologic radon potential   ,
areas (fig. 9) and each areff assigned Radon Index (RI) and Confidence Index (CI) scores
(Table 2). The Radon Index is a semiquantitative measure of radon potential based on geologic,
soil, and indoor radon factors, and the Confidence Index is a measure of the relative confidence of
the RI assessment based on the quality and quantity of data used to make the predictions (see ,the
Introduction chapter for more information on the methods and data used). At the scale of this
report the outlines of the areas shown oh figure 9 are generalized, and the descriptions given in this
text should be compared with more detailed geologic and other maps.             '
       Area PPR is.underlain by Pennsylvanian and Permian rocks. Homes in this area may have
indoor radon levels ranging from low (<2 pCi/L) to high (>4 pCi/L}, depending on the local
underlying geology and presence and thickness of loess cover. Additional indoor radon data
compiled by the Kansas Department of Health and Environment (written communication, 1992)
suggest that more homes in this area have moderate to high indoor radon levels than are indicated
by the State/EPA Residential Radon Survey data, so the indoor radon factor was assigned 2 points,
but because the data are partially from a non-randomly-sampled volunteer source, the factor is
given 2, rather than 3, confidence index points.  Homes built on uranium-bearing Pennsylvanian
black shales within this area may have locally high indoor radon levels. Some areas underlain by
carbonate rocks (limestones and dolomites) may have locally elevated indoor radon levels,
especially if solution features or clay-rich residual soils have developed (the residual soils are
commonly red or orange-red in color due to concentration of iron .oxides in the residuum). Some
domestic wells drawing water from lower Paleozoic aquifers in this area may contribute to elevated
'radon levels by release of dissolved radon from the water into the indoor air. Area PPR is
assigned a moderate or variable overall radon potential (RI=9) with moderate confidence (CI=9).
       Area GLA is underlain by glacial drift and loess of varying thickness. Although the
bedrock source for the glacial drift can be traced as far as the Canadian Shield, a large proportion
of the drift is relatively locally derived from underlying and nearby Paleozoic sedimentary rocks
that are relatively poor radon sources. Higher permeability of the drift relative to bedrock, the
presence of crystalline glacial erratics, and the variability of loess  cover and  source (primarily
glacially derived) cause this area to have moderate to high radon potential, and it is assigned.an
overall high geologic radon potential (RI=12), with a high confidence index (CI=10).
       Area MCR is an area of faults and fractures related to the Mid-Continent Rift zone. Homes
sited on unfaulted Permian bedrock in this area are likely to have low radon levels, but those sited
on surface or near-surface faults or fractures may have locally high indoor radon levels. The
boundaries of the area aYe drawn along major subsurface faults that delineate the rift system    ,
(Berendsen and others, 1989). Overall, area MCR is assigned a high radon potential (RI=12) with
high confidence (CI=10).           .
       Area KR delineates the bedrock outcrop pattern of Cretaceous sedimentary rocks in
Kansas. Parts of this area, particularly the western part, are covered by discontinuous loess
deposits.  Gray and black shale units of the Pierre Shale typically  generate moderate to high indoor
radon levels. The Dakota and Niobrara Formations and the Pierre Shale are known to contain
locally anomalous amounts of uranium and are known producers  of elevated radon in some areas.
Overall, area KR has a higkradon potential (RI=12) with high confidence (CI=11).. •
       Area TL is mostly underlain by Tertiary rocks, specifically the Ogallala Formation, that are
mostly covered by younger loess.deposits. The highest radon levels in this area are expected" to
                                           IV-19..   Reprinted from USGS Open-File Report 93-292-G

-------
occur In homes sited on siliceous (silica-cemented) Ogallala Formation, particularly in the
southwestern part of the State.  Radon levels in structures built on loess deposits are expected to
range from moderate to high depending on the thickness and mineralogy of the loess. Because the
indoor radon data indicate that many areas underlain by loess or Tertiary sedimentary rocks have
county average indoor radon levels exceeding 4.0 pCi/L, and because many of the counties in
western Kansas have relatively few sampled homes in the State/EPA survey, a conservative
approach to ranking the area was adopted. Indoor radon levels in this area are expected to range
from low (< 2 pCi/L) to high (> 4 pCi/L) but are most likely to be in the moderate to high range,
so area TL is assigned an overall high radon potential (RI=12) with high confidence  (CI=11).
       DS denotes areas underlain by dune sands in the Arkansas and Cimarron River valleys.
The dune sands are highly permeable, but because they are composed almost entirely of quartz
grains containing little or no uranium or radium, they generally generate low radon levels. If the
deposits are thin (less than approximately 15 ft thick), the sands are likely to transmit radon from
the underlying bedrock toward the surface and into homes built on these deposits.  Relatively
higher indoor radon levels are also more likely to occur where the sands are mixed with loess
deposits. Area DS is assigned a moderate or variable geologic radon potential (RI=10), with a
high confidence index (CI=11).
       This is a generalized assessment of the State's geologic radon potential and there is no
substitute for having a home tested. The conclusions about radon potential presented in this report
cannot be applied to individual homes or building sites. Indoor radon levels, both high and low,
can be quite localized, and within any radon potential area there will likely be areas with higher or
lower radon potential that assigned to the area as a whole. Any local decisions about radon should
DM be made without consulting all available, local data.  For additional information on radon and
how to test, contact your State radon program or EPA regional office. More detailed information.
on state or local geology may be obtained from the State geological survey.  Addresses and phone
numbers for these agencies are listed in chapter 1 of this booklet.
                                          IV-20   Reprinted from USGS Open-File Report 93-292-G

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TABLE 2. Radon Index (RI) and Confidence Index (CI) scores for geologic radon potential areas
         of Kansas.  See figure 9 for locations of areas.
-, . - ••" ' 'AREA; ' ' ;
PPR
FACTOR
1ND(X)R RADON
RADIOACHVTTY
GEOLOGY
SOIL PERM.
ARCHITECTURE
GEE POINTS
TOTAL
. RANKING
RI
2
2'
2 '
- ,1 ,
2 •
' 0
9
MOD
CI
2
3
2
2
-,
1 • -._
9
MOD
KR
FACTOR
INDOOR RADON
RADIOACTIVITY
GEOLOGY
. SOIL PERM.
. ARCHITECTURE
GFE POINTS
TOTAL
RI
2
...2
'3
•"2
,3 .
0
12
CI
•3
3 .
••3
2 -
- ' "
' ".— ' " .
11
GLA
RI
2
.' '2- .
• 3'
' 2 '
• 3
0
' 12
HIGH'
CI
3' •'
2 •
- 3
• 2 . '
_
, •'_ .'
10 -
HIGH
TL
RI
, 2
.-2V
. 3. '
' 2
3
0
•- 12 '
CI
•3 ' •
3 .
•'3
-...-I
_
• _
11
. MCR
RI
3 ..
2
3
' 1
'- 3 :
0
' • 12= '
' - -HIGH ''
DS
RI
• . ' • 2
1
1 2
" •. 2
3
0
10
CI
3 .'
3
2
2
' -
_
10
HIGH

CI
.3 ,
3
3
2
- .
_
11
                 RANKING 'HIGH  HIGH
HIGH ' HIGH
MOD. HIGH
RADON INDEX SCORING:
                                                   Probable screening indoor
Radon potential category
LOW
MODERATE/VARIABLE
HIGH
Point range
3-8 points
9-11 points
> 11 points , "
radon average for area
<2pCi/L
2~4pCi/L
>4pQ/L
                          Possible range of points = 3 _to 17

CONFIDENCE INDEX SCORING:
         LOW CONFIDENCE
         MODERATE CONFIDENCE
         HIGH CONFIDENCE
 4-6 points
 7-9 points
10-12 points
                          Possible range of points = 4 to 12
                                     IV-21   Reprinted from USGS Open-File-Report 93-292-G

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RADON POTENTIAL:
                                                    MODERATE
HIGH
Figure 9. Geologic radon potential areas of Kansas. See Table 2 and text for descriptions and rankings of areas.

-------
                         REFERENCES USED IN THIS REPORT
           AND GENERAL REFERENCES PERTAIMNG TO RADON IN KANSAS

 Bainum, D., Barton, J., Miller, D., To, D. and Trupp, R., 1989, Radon concentration in houses
        in the vicinity of Topeka, Kansas: Transactions of the Kansas Academy of Science, v. 92,
        p. 63-69.      '     . •:      ";.  ,   s  '    , '';          •    • .   .  'A    ,  '   :';

 Berendsen, P., and Hathaway, L.R., 1981, Uranium in unconsolidated aquifers of western
        Kansas: Kansas Geological Survey Mineral Resource Series 9,43 p.

 Berendsen, P., and Blair, K.P.; 1986, Subsurface structural maps over the Central North
        American rift system (CNARS), central Kansas, with discussion: Kansa§*Geologieal
        Survey Subsurface Geology Series 8,16 p., 7 plates.
. "   s  '       ,     -    \
                                                       " %           -
• Berendsen, P., Hathaway, L.R. and Macfarlane, P.A., 1988, Radionuclide distributions in the
        natural environment in Kansasa review of existing data, in M.A. Marikos and R.H.
        Hansman (eds), Geologic causes of natural radionuclide anomalies: Proceedings of
        GEORAD conference, St. Louis, MO, Apr. 21-22,1987, Missouri Department of Natural -
        Resources Special Publication 4, p. 65-74.                        ••*>.-
                                  t          '       '                 ' "*"
 Berendsen, P., Newell, K.D., and Blair, K.P., 1989, Structural aspects of the mid-content rift
        system in Kansas: American Association of Petroleum Geologists Bulletin, .v. -73, p.
        1043.                                                  ,        .  .  r  •

 Bidwell, O.W., and McBee, C.W., compilers, 1973, Soils of Kansas: Kansas Agricultural. •
        Experiment Station, Department of Agronomy Contribution No, 1359, scale  1:1,125,000,.
                                                   f                         -
 Brookins, D.G., 1970,  The Mmberlites of Riley County, Kansas: Kansas Geological Survey
        Bulletin 200, p. 3-32.                       ,                     '

 Carey, S.J., Frye, J.C., Plummer, N., and Swineford, A., 1952, Kansas volcanic-asri'resources:
        Kansas Geological Survey Bulletin 96, 68 p.
              '              **     i                        '                    '
 Carmichael, R.S., 1989, Practical Handbook of physical properties of rocks and minerals: Boca
        Raton, Ela., CRC Press, 741 p.-                .  ,-    "                  .

 Coveney, R.M., Jr., Hilpman, P.L., Allen, A.V., and Glascockj M.D., 1988, Radionuclides in
        Pennsylvanian  black shales of the midwestern United States, in M.A. Marikos and R.H.
        Hansman (eds), Geologic causes of natural radionuclide anomalies: Proceedings of
        GEORAD conference, St Louis, MO, Apr. 2i-22,1987, Missouri Department of Natural
        Resources Special Publication 4, p. 25-42.       •

, Cullers, R.L., Ramakrishnan, S., Berendesn,  P., and Griffin, T., 1985, Geochemistry and
        petrogeriesis of lamproites, Late Cretaceous age, Woodson County, Kansas, US A:'
        Geochimica et  Cosmochimica Acta, v. 49, p.  1383-1402.
                                         TV-23   Reprinted-firom US!3S Open-File Report 93-292-G

-------
Dort, Wakefield, Jr., 1987, Salient aspects of the terminal zone of continental glaciation in Kansas,
       in Johnson, W.C., ed., Quaternary environments of Kansas:  Kansas Geological Survey
       Guidebook Series no. 5, p. 55-66.

Duval, J.S., Jones, W.J., Riggle, F.R., and Pitkin, J.A., 1989, Equivalent uranium map of the
       conterminous United States:  U.S. Geological Survey Open-File Report 89-478,10 p.

Gundersen, L.C.S., 1991, Radon in sheared metamorphic and igneous rocks, in Gundersen,
       L.C.S., and Wanty, R.B.  (eds), Field studies of radon in rocks, soils, and water: U.S.
       Geological Survey Bulletin 1971, p. 39-50.                .                   ,

James, G.W., 1977, Uranium and thorium in volcanic ash deposits of Kansas:  Implications for
       uranium exploration in the Central Great Plains, in Waldron, G.A.; ed, Short Papers on
       Research in 1977: Kansas Geological Survey Bulletin 211, part 4, p. 1-3.

Landis, E.R., 1959, Radioactivity and uranium content, Sharon Springs Member of the Pierre
       Shale, Kansas and Colorado: U.S. Geological  Survey Bulletin 1046-L, p. 299-319.

Macfarlane, P.A.,  1981, Distribution of radium-226 in the lower Paleozoic aquifers of southeast
       Kansas and adjacent areas, in Hemphill, D.D., (ed), Trace substances in environmental
       health XIY, a symposium: Columbia, Missouri, University of Missouri, p. 78-85.

Olson, J.W., 1974, Using soils,of Kansas for waste disposal: Kansas Geological Survey Bulletin
       208,51 p.                                                              .       :

Ross, Jorgina A., compiler, 1991, Geologic map of Kansas:  Kansas Geological Survey, scale
       1:500,000.

Schumann, R.R., Owen, D.E., and Asher-Bolinder, S., 1989, Weather factors affecting soil-gas
       radon concentrations at a single site in the semiarid western U.S., in Osborne, M.C., and
       Harrison, J., Symposium  Cochairmen., Proceedings of the 1988 EPA Symposium on
       Radon and Radon Reduction Technology, v. 2,  EPA Publication EPA/600/9-89/006B,
       p. 3-1 to 3-13.

Schumann, R.R., Peake, R.T., Schmidt, K.M., and Owen, D.E., 1991, Correlations of soil-gas
       and indoor radon with geology in glacially derived soils of the northern Great Plains, in
       Proceedings of thfe 1990 International Symposium on Radon and Radon Reduction
       Technology, Volume 2, Symposium Oral Papers:  U.S.  Environmental Protection Agency
       report EPA/600/9-9l/026b, p. 6-23-6-36:

Steeples, D.W., and Buchanan, Rex, 1983, Kansas geomaps: Kansas Geological Survey
       Educational Series 4,30 p.

Wagner, H.C., 1954, Geology of the Fredonia quadrangle, Kansas:  U.S. Geological Survey Map ,
       GO-49.                                               .
                                         IV-24    Reprinted from USGS Open-File Report 93-292-G

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Welch, I.E., and Hale, J.M., 1987, Pleistocene loess in Kansasstatus, present problems, and
       future considerations, in Johnson, W.C., ed., Quaternary environments of Kansas:
       Kansas Geological Survey Guidebook Series no. 5, p. 67-84.       ,

Wilson, Frank, 1984, Landscapes: A geologic diary, in Buchanan, Rex, ed,, Kansas geology:
       Lawrence, Kansas, University of Kansas Press, p. 9-39.

Wilson, F.W., 1979, A study of the regional tectonics and seismicity of eastern Kansas—
     . summary of project activities and results to the end of the second year, or September 30,
       1978: U.S. Nuclear Regulatory Commission report NUREG/CR-0666, 68 p.

Zeller, E.J.; Dreschhoff, G,, Angino, E., Holdoway, K., Hakes, W., Jayaprakssh, G., Crisler,
       K,, and Saunders, D.F., 1976, Potential uranium host rocks and structures in the central
       Great Plains:  Kansas Geological Survey Geology Series 2,59 p.

ZielinsM, R.A., 1983, Tuffaceous sediments as source rocks for uranium—A case study of the
       White River Formationj Wyoming: Journal of Geochemical Exploration, v. 18,
     .  p. 285-306.
                                                '.  . '    "      /   v
                                          IV-25-  Reprinted from USGS.Opeft-Fiie Report 93-292-G

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Page Intentionally Blank

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                            EPA's Map of Radon Zones
       The USGS' Geologic Radon Province Map is the technical foundation for EPA's Map
 of Radon Zones.  The Geologic Radon Province Map defines the radon potential for
 approximately 360 geologic provinces. EPA has adapted this information to fit  a county
 boundary map in order to produce the Map,of Radon Zones.             .
       The Map of Radon Zones is based on the same range of predicted screening levels of
 indoor radon as USGS' Geologic Radon Province Map.  EPA .defines the three zones as •
 follows:  Zone One areas have an average predicted indoor radon screening potential greater
 than 4 pCi/L. Zone Two areas are predicted to have an  average indoor _radon-«&creening
 potential  between  2 pGi/L mnd 4 pCi/L.  Zone  Three areas are predicted to have an average
 indoor radon screening potential less than 2 pCi/L.
       Since the geologic province boundaries cross state and county boundaries, a strict
 translation of counties from the Geologic Radon Province Map to the Map of Radon Zones
 was not possible. * For counties that have variable radon  potential (i.e.j are located  in two or
 more provinces  of different rankings), the counties were assigned to "a zone  based on the
 predicted radon  potential of the province in which most,  of its area lies. (SeevPart I for more
 details.)              -_                 :    •       ' .;'     .-.'   •

 KANSAS MAP OF RADON  ZONES  •          .     '.        ,  .        ...... ..„    -   '    '

       The Kansas'Map  of Radon Zones and its supporting documentation (Part IV of this
 report) have received extensive review by Kansas geologists and radon program experts.  The
 map for Kansas generally reflects current State knowledge about radon for its counties.  Some
• States have been able to  conduct radon investigations in  'areas smaller  than geologic provinces
 and counties, so it is important to consult locally available, data.      •  .>•,.•;•,.•**       .. "
       Two county designations do not strictly follow the methodology for  adapting the
 geologic provinces to county boundaries.  EPAj and the  Kansas Department of Health and the
 Environment have decided to  designate Douglas and Marion counties as Zone 1.  Although
 these areas  are rated as having a moderate radon potential on the whole, areas of variability
• and high  radon potential are known to. exist in these counties.  Supplemental indoor radon
 data that  was submitted by the Kansas Department of Heal-th and the Environment indicate
 that these counties have significant percentages of homes above 4 pCi/L and therefore warrant
 Zone  1 designations.                                  •                                ,
       Althougrrthe information  provided in Part IV of  this report -- the State chapter entitled
 "Preliminary Geologic Radon  Potential Assessment-.of Kansas"  — may appear to be quite
 specific, it cannot  be applied to determine the radon levels of a neighborhood, housing tract,.
 individual house, etc.'  THE .ONLY WAY, TO  DETERMINE  IF A'HOUSE'HAS  '  :   •
 ELEVATED INDOOR  RADON IS TO TEST. • Contact the Region 7 EPA office' or the"
 Kansas program for information on testing and fixing homes. Telephone numbers and
 addresses pan be found in Part II of this report                      "
                                          V-l

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KANSAS -  EPA Map  of Radon  Zones

      Th« purpow of ftfe map h to assist NatonaJ, StoJt emd tecal orjjanbatJorw
      to target ttwfr resources end to Imptoment rodwMesJstant building codas.
   This map Is not Intended to determine if a home in a given zone should be tested
   for radon. Homes with elevated levels of radon have been found in all three
   zones.  AH homos should bo tested, regardless of zono designation.
                                                                                                            DONIPHAN
 Zone 1
Zone 2
Zone 3
IMPORTANT: Consult the publication entitled "Preliminary Geologic Radon
Potential Assessment of Kansas* before using this map. This
document contains information on radon potenial variations wittiin counties.
EPA also recommends that this map be supplemented with any available
local data in order to further understand and predict the radon potential of a
specific area.

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