United States
                     Environmental Protection
                     Agency
Air and Radiation
(6604J)
402-R-B3-OS9
September 1993
           &EPA  EPA's Map of Radon Zones

                     WEST VIRGINIA
'€

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       EPA'S MAP OF RADON ZONES
             WEST VIRGINIA
             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. Thomas 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.

       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 surveys 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 3 GEOLOGIC RADON POTENTIAL
                 SUMMARY
 V. PRELIMINARY GEOLOGIC RADON POTENTIAL
        ASSESSMENT OF WEST VIRGINIA
V. EPA'S MAP OF RADON ZONES -- WEST VIRGINIA

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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 and
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 sources 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 en^dedJVAreas_m^                      	
Levels."  This map was 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, USGS1 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
information, particularly the data from the National Uranium Resource Evaluation project.
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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 types.
       The predictions of average screening levels in each of the Zones  is an expression of
 radon potential 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 to Radon Reduction and the Home Buyer's and Seller's Guide to
Radon.
       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 app,coximately.J360.separate,geologic provinces...for-.the-U.S7-—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
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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 of 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 Radon Zones by extrapolating from the
 province level to the county  level so that all counties in the U.S. were assigned 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 a predicted
 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 the 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 within-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
P9*®!*!?! JPJTJh±J?!^r_eJJnite_d_Sjate^J^        i^t are used in jthis effQjt_"indoor_..radQn	
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.
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Figure 3
                 Geologic  Radon  Potential  Provinces for  Nebraska
         Llacolo Count
           Hiji      Koierilt      Low
Figure 4
         NEBRASKA  -  EPA  Map  of Radon Zones
        Li ac ol a_Cpti fl t y  -
         Zone 1    Zoie Z    Zone 3
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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 meteorology 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.
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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
 'cognations.  In a few cases, States have  requested Changes in county zone de ignations.  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.
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     THE USGS/EPA RADON POTENTIAL ASSESSMENTS: AN INTRODUCTION
                                            h
                      Linda C.S. Gundersen and R. Randall Schumann
                                  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
 Interagency Agreement between the EPA and the U.S. Geological Survey (USGS), the USGS
 has prepared radon potential estimates for the United  States. This report is one 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 general
 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.
     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 discussion 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
 (Part IV).  Each state chapter discusses the state's specific geographic setting, soils, geologic
 setting, geologic radon potential, indoor radon data, and  a summary outlining the 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 radon 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 homes or housing


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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 U.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 (222Rn) is  produced from the  radioactive  decay of radium (226Ra),  which is, in turn,
 a product of the decay of uranium (23*U) (fig. 1).  The half-life of 222Rn is 3.825  days. Other
 isotopes of radon occur  naturally, but, with the exception of thoron (220Rn), 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 un weathered ^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


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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 platy
 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 soil'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, 1987).  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 area's 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  = 10'9 meters), or about 2x10"6 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-driven flow of radon-laden air from subsurface


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solution cavities in the carbonate rock into houses.  As warm air enters solution cavities that
are higher on the hillslope than the homes, it cools and settles, pushing radon-laden air from
lower in the cave or cavity system into structures on the hillslope (Gammage and others,
1993). In contrast, homes built over  caves having openings situated below the level of the
home had higher indoor radon levels  in the winter, caused by  cooler outside air 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 nonbasement homes.  The term "nonbasement" applies to
slab-on-grade 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 radiometric; (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 tietermining-radon potential.—Rockrlypes 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-poor metamorphic and


                                           II-5     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 and radium are
 commonly sited  in heavy minerals, iron-oxide costings on rock and soil grains, and organic
 materials in  soils and sediments. Less common are uranium associated with phosphate 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).

 MURE 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 C'-'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 collectedly  aircrafrin~~which~alpim
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 errors 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 93-292

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                  FL1CHT LINE  SPACING Of  SURE AEKlAL  SURVEYS
                     2 KM  (1 KILE)
                     5 £U  (3 MILES)
                     2 i 5  KM
                 E3 10 III  (6 IIILES)
                     5 t 10  EH
                     NO DATA
Figure 2. Nominal flightline spacings for MURE aerial gamma-ray surveys covering the
contiguous United States (from Duval 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 01  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 minerals 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.  The 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 93-292

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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 in 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 \v Jl with gas permeability.  Jecause 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 largest source of data is
 from the State/EPA Residential Radon Survey (Ronca-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, detached housing units (White and  others,  1989), although attached structures
such as  duplexes, townhouses, or condominiums were included in some of the 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 surveys 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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     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 in 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, or
 the schemes were not considered sufficient to"provide antreansnof consistenrcomparison	
 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 not 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


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

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TABLE 1. RADON INDEX MATRIX, "ppm eU" indicates parts per million of equivalent
uranium, as indicated by NURE aerial radiometric data. See text discussion for details.

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

POINT VALUE
1
<2pCi/L
< 1.5 ppm eU
negative
low
mostly slab
2
2 - 4 pCi/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 studies. 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
            LOW
            MODERATE/VARIABLE
            HIGH
                                   Probable average screening
                      Point range	indoor radon for area
                      3-8 points
                      9-11 points
                     12-17 pouits
           <2pCi/L
           2-4pCi/L
           >4pCi/L
                      POSSIBLE RANGE OF POINTS = 3 to 17
TABLE 2.  CONFIDENCE INDEX MATRIX
                                     INCREASING CONFIDENCE
	 ^
FACTOR
INDOOR RADON DATA
AERIAL RADIO ACTIVITY
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
                                     II-12     Reprinted from USGS Open-FUe 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 NUKE 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 of "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 geochemical 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 to 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
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 Wisconsin-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)"caiegory7~"~
    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 or 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 data (likely to be nonrandom and biased
 toward population centers and/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 elJ, 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-point 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 for 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
tesf frgufes'bTlSmerSeas^
 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  closely 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
not 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 CITED

 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, ID., 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
       (S AGEEP), Golden, Colorado, March 13-16,1989: Society of Engineering and Mineral
       Exploration Geophysicists, p. 1-61.

 Duval, J.S., Cook, B.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, Equivalent uranium 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 on Radon and Radon Reduction Technology, Vol. IJJ: 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,' Subtereanean 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., 1988a, Correlation between geology, radon
       in soil gas, and indoor radon in the Reading Prong, in Marikos, M. A., and Hansman,
       R.H., 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 hi 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.
                                        H-17     Reprinted from USGS Open-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/600/9-89/006A, 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., 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.Mv, 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.
                                         II-18     Reprinted from USGS Open-File Report 93-292

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 Schumann, R.R., Owen, D.E., and Asher-Bolinder, 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, Term., 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 Lowder,
       W.M., eds., The natural radiation environment:  Chicago, El., University of Chicago
       Press, p. 161-190.

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

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

 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 Survey 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.
                                         JJ-19     Reprinted from USGS Open-FUe Report 93-292

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                                               APPENDIX  A
                                       GEOLOGIC  TIME SCALE
Subdivisions (and their symbols)
Eon or
Eonothem
Phanerozoic2

Proterozoic
(c)

Archean
IA)

Era or
Erathem
Cenozoic 2
(Cz)
Mesozoic2
(Mi)
Paleozoic2
 Paleogene
11 Suboenodor
Subsystem (Pi)
Cretaceous
(K)
Jurassic

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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 picocurie (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 uranium 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

 aerial radiometric, aeroradiometric survey A survey of radioactivity, usually gamma rays,
 taken by an aircraft carrying a gamma-ray spectrometer pointed at the ground surface.

 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.

 alluvium, alluvial General terms referring to unconsolidated detrital material deposited by a
 stream or other body of running water.

. alpha.-track jaete.ctor_A passivejadonjneasurement device consisting of a plastic fihn 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.

 amphibolite A mafic metamorphic rock consisting mainly 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 (€63) 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 may be
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.

    diorite  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
    quartz.

    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, or 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 Any 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 crystallinerquartz- 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 consisting 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
                                              n-23     Reprinted from USGS Open-FUe 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 into which rocks are divided, the others being sedimentary and
metamorphic.

intermontane A term that refers to an area between two mountains or mountain ranges.

intrusion, intrusive The processes of emplacement or injection of molten rock into pre-existing
rock. Also refers to the rock formed by intrusive processes, such as an "intrusive igneous rock".

kame A low mound, knob, hummock, or short irregular ridge formed by a glacial stream at the
margin of a melting glacier; composed of bedded sand and gravel.

karst terrain A type of topography that is formed on limestone, gypsum and other rocks by
dissolution of the rock by water, forming sinkholes and caves.

lignite A brownish-black coal that is intermediate in coalification between peat and
subbituminous coal.

limestone A carbonate sedimentary rock consisting of more than 50% calcium carbonate,
primarily in the form of the mineral calcite
lithology  The description of rocks in hand specimen and in outcrop on the basis of color,
composition, and grain size.

loam A permeable soil composed of a mixture of relatively equal parts clay, silt, and sand, and
usually containing some organic matter.

loess A fine-grained eoHan deposit composed of silt-sized particles generally thought to have
been deposited from windblown dust of Pleistocene age.

mafic Term describing an igneous rock containing more than 50% dark-colored minerals.

marine Term describing sediments deposited in the ocean, or precipitated from ocean waters.

metamorphic Any rock derived from pre-existing rocks by mineralogical, chemical, or structural
changes in response to changes in temperature, pressure, stress, and the chemical environment.
PhylSte, schist, amphibolite, and gneiss are metamorphic rocks.

moraine A mound, ridge, or other distinct accumulation of unsorted, unbedded glacial material,
predominantly till, deposited by the action of glacial ice.

outcrop That part of a geologic formation or structure that appears at the surface ofthe Earth, as
in "rock outcrop".

percolation test A term used in engineering for a test to determine the water permeability of a
soil. A hole is dug and filled with water and the rate of water level decline is measured.

permeability  The capacity of a rock, sediment, or soil to transmit liquid or gas.

phosphate, phosphatic, phosphorite  Any rock or sediment containing a significant amount
of phosphate minerals, i.e., minerals containing PO4.


                                          11-24     Reprinted from USGS Open-File Report 93-292

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   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.

   olacer deposit See heavy minerals

   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 or 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 into
   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 ductile 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.

—solutionicavity ^holeT'chamellJ^

   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 on the
   earth's surface.

   tablelands General term for a broad, elevated region with a nearly level surface of considerable
   extent.
                                             11-25      Reprinted from USGS Open-File Report 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 an 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.
                                          11-26 .     Reprinted from USGS Open-File 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
(2AIR: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 (6T-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-3)
75 Hawthorne Street
San Francisco, CA 94105
(415) 744-1048
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	7
 Kansas	.•	7
 Kentucky	4
 Louisiana	6
 Maine	l
 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
 Virginia	3
-.Washington	,».,„„».-.. ,.-..-^^.-^.^-10-
 West Virginia	3
 Wisconsin	5
 Wyoming	8
                                                n-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
                Charles Tedford
                Department of Health and Social
                  Services
                P.O. Box 110613
                Juneau.AK 99811-0613
                (907)465-3019
                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       Linda Martin
               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 06106-4474
             (203)566-3122

   Delaware  Marai G. Rejai
             Office of Radiation Control
             Division of Public Health
             P.O. Box 637
             Dover, DE 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
              Rehabilitative Services
             1317 Winewood Boulevard
             Tallahassee, EL 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 AlaMoanaJBQuleyard_  __
            Honolulu, ffl 96813-2498
            (808) 586-4700
                                               IE-28      Reprinted from USGS Open-File Report 93-292

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Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
 PatMcGavarn
 Office of Environmental Health
 450 West State Street
 Boise, ID 83720
 (208) 334-6584
 1-800-445-8647 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. Plater
 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

 JeanaPhelps
 Radiation 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
              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. Rachuba
              Radiological Health Program
              Maryland Department of the
                Environment
              2500 Broening Highway
              Baltimore, MD 21224
              (410)631-3301
              1-800-872-3666 In State

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 Sue Hendershott
              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  Laura Oatmann
              Indoor Air Quality Unit
              925 Delaware Street, SE
              P.O. Box 59040
              Minneapolis, MN 55459-0040
  	(612)627-5480	
              1-800-798-9050 in state
                                                n-29      Reprinted from USGS Open-File Report 93-292

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 Mississippi     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

 Missouri        Kenneth V. Miller
                Bureau of Radiological Health
                Missouri Department of Health
                1730 East 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
Nebraska        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

Nevada          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
                ConcordrNH 03301	
                (603)271-4674
                1-800-852-3345 x4674
    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 St. 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
              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
                                               H-30
       Reprinted from USGS Open-File Report 93-292

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 Oklahoma
Oregon
Pennsylvania
Puerto Rico
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 97201
(503)731-4014
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 Piedras, Puerto Rico 00936
(809) 767-3563
Edmund Arcane!
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
 South Dakota  MikePochop
              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

    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
              288 North, 1460 West
              P.O. Box 16690
              Salt Lake City, UT 84116-0690
              (801) 536-4250

         2Di  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 JJ
              in New York
                                               n-3i
                                           Reprinted from USGS Open-File Report 93-292

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Virginia         Shelly Ottenbrite
                Bureau of Radiological Health
                Department of Health
                109 Governor Street
                Richmond, VA 23219
                (804)786-5932
                1-800-468-0138 in state

Washington      Kate Coleman
                Department of Health
                Office of Radiation Protection
                Airdustrial Building 5, LE-13
                Olympia, WA 98504
                (206) 753-4518
                1-800-323-9727 In State

West Virginia    Beattie L. 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
               Conrad Weiffenbach
               Radiation Protection Section
               Division of Health
               Department of Health and Social
                 Services
               P.O. Box 309
               Madison, WI 53701-0309
               (608) 267^796
               1-800-798-9050 in state
Wyoming      Janet Hough
               Wyoming Department of Health and
                 Social Services
               Hathway Building, 4th Floor
               Cheyenne, WY 82002-0710
               (307)777-6015
               1-800-458-5847 in state
                                                H-32      Reprinted from USGS Open-File Report 93-292

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                              STATE  GEOLOGICAL  SURVEYS
                                              May, 1993
  Alabama       Ernest A. Mancini
                Geological Survey of Alabama
                P.O. Box 0
                420 Hackberry Lane
                Tuscaloosa, AL 35486-9780
                (205) 349-2852

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

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

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

 Colorado        Pat Rogers (Acting)
                Colorado Geological Survey
                1313  Sherman St., Rm 715
                Denver, CO 80203
                (303) 866-2611

 Connecticut      Richard C. Hyde
                Connecticut Geological & Natural
                  History Survey
                165 Capitol Ave., Rm. 553
._	Hartford, CT 06106	
                (203) 566-3540

 Delaware        Robert R. Jordan
                Delaware Geological Survey
                University of Delaware
                101 Penny Hall
               Newark, DE 19716-7501
                (302)  831-2833
  Florida Walter Schmidt
         Florida Geological Survey
         903 W. Tennessee Su
         Tallahassee, FL 32304-7700
         (904)488-4191
 Georgia William H. McLemore
         Georgia Geologic Survey
         Rm. 400
         19 Martin Luther King Jr. Dr. 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 96809
         (808) 548-7539

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

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

 Indiana  Norman C. Hester
         Indiana Geological Survey
         611 North Walnut Grove
         Bloomington, IN 47405
         (812) 855-9350

   Iowa  Donald L. Koch
         Iowa Department of Natural Resources
         Geological Survey Bureau
         109 Trowbridge Hall
	—-Iowa City, IA52242;1319	
         (319) 335-1575

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

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Kentucky
Louisiana
Maine
Maryland
Massachusetts
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 St, Room 2000
Boston, MA 02202
(617) 727-9800

R. Thomas Segall
Michigan Geological Survey Division
Box 30256
Lansing, MI 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 &
                  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, NE 68588-0517
                (402)472-2410
                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

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

    New Mexico  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
                                               IE-34      Reprinted fiom USGS Open-File Report 93-292

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   North Carolina  Charles H. 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
                 600 East Blvd.
                 Bismarck, ND 58505-0840
                 (701) 224-4109
  Ohio           Thomas M. Berg
                 Ohio Dept. 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
                 lOOE.Boyd
                 Norman, OK 73019-0628
                 (405) 325-3031

 Oregon          Donald A. Hull
                 DepL of Geology & Mineral Indust.
                 Suite 965
                 800 NE Oregon St. #28
                 Portland, OR 97232-2162
                 (503)731-4600

 Pennsylvania     Donald M. Hoskins
                 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
                 315 Green Hall
                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
              VermUlion, 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. Foothill Dr.
              Salt Lake City, UT 84109-1491
              (801)467-7970
     Vermont  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
                                                n-35      Reprinted from USGS Open-File Report 93-292

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  West Virginia  Larry D.Woodfoik
               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
               3817 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-36      Reprinted from USGS Open-File Report 93-292

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               EPA REGION 3 GEOLOGIC RADON POTENTIAL SUMMARY
                                            by
                 Linda C.S. Gundersen, James K. Otton, and Sandra L. Szarzi
                                  U.S. Geological Survey

        EPA Region 3 includes the states of Delaware, Maryland, Pennsylvania, Virginia, and
 West Virginia.. 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 pCi/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 to this volume. More detailed information on the geology and radon
 potential of each state in Region 3 is given in the individual state chapters. The individual chapters
 describing the geology and radon potential of the states in EPA Region 3, though much more
 detailed than this summary, still are generalized  assessments and there is no substitute for having a
 home tested. Within any radon potential area homes with indoor radon levels both above and
 below the predicted average will likely be found.
        Figure 1 shows a generalized map of the major physiographic/geologic provinces in EPA
 Region 3.  The summary of radon potential in Region 3 that follows refers to these provinces.
 Figure 2 shows average screening indoor radon levels by county. The data for Maryland,
 Pennsylvania, Virginia, and West Virginia are from the State/EPA Residential Radon Survey. Data
 for Delaware were compiled by the Delaware Department of Health and Social Services. Figure 3
 shows the geologic radon potential areas in Region 3, combined and summarized from the
 individual state chapters in this booklet.

 DELAWARE

 Piedmont
        The Piedmont in Delaware has been ranked moderate in geologic radon potential. Average
 measured indoor radon levels in the Piedmont vary from low (<2 pCi/L) to moderate (2-4 pCi/L).
 Individual readings within the Piedmont can be locally very high (> 20 pCi/L). This is not
 unexpected when a regional-scale look at the Atlantic coastal states shows that the Piedmont is
 consistently an area of moderate to high radon potential. Much of the western Piedmont in
 Delaware is underlain by the Wissahickon Formation, which consists predominantly of schist.
 This formation has moderate to locally high geologic radon potential. Equivalent schists in the
 Piedmont of Maryland can have uranium concentrations of 3-5 ppm, especially where faulted.
.^.^l^^fL^^^
 Delaware Piedmont, are variable in radon potential. In these units^the felsic gneiss and schist may
 contribute to elevated radon levels, whereas mafic rocks such as amphibolite and gabbro, and
 relatively quartz-poor granitic rocks such as charnockite and diorite are probably lower in radon
 potential.  The average indoor radon is distinctly lower in parts of the Wilmington Complex than in
 surrounding areas, particularly in areas underlain by the Bringhurst Gabbro and the Arden pluton.
 The permeability of soils in the Piedmont is variable and dependent on the composition of the rocks
 from which the soils are derived. Most soils are  moderately permeable, with local areas of slow to
                                          m-1     Reprinted from USGS Open-FUe Report 93-292-C

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                                                                                              100
                                                                                  miles
Figure 1. Geologic radon potential areas of EPA Region 3. 1-Central Lowland; 2-Glaciated Pittsburgh Plateau-
3-Pennsylvanian rocks of the Pittsburgh Low Plateau; 4-Permian rocks of the Pittsburgh Low Plateau; 5-High Plateau
Section; 6-Mountainou^High Plateau; 7-Allegheny.Plateaui and.Mountains; 8-Appalachian Mountains;-9-Glaeiated-
Low Plateau, Western Portion; iCMjlaciated Pocono Plateau; 1 l-<31aciated Low Plateau, Eastern Portion;
12-Reading Prong; 13-Great Valley/Frederick Valley carbonates and elastics; 14-Blue Ridge Province;
15-Gettysburg-Newark Lowland Section (Newark basin) 16,34-Piedmont; 17-AUantic Coastal Plain; 18-Central
Allegheny Plateau; 19-Cumberland Plateau and Mountains; 20-Appalachian Plateau; 21-Silurian and Devonian rocks
in Valley and Ridge; 22,23-Valley and Ridge (Appalachian Mountains); 24-Western Piedmont Phyllite;
25-Culpeper, Gettysburg, and other Mesozoic basins; 26-Mesozoic basins; 27-Eastem Piedmont, schist and gneiss-
28-Inner Piedmont; 29-Goochland Terrane; 30,31-Coastal Plain (Cretaceous, Quaternary, minor Tertiary sediments)-
32-Carolina terrane; 33-Coastal Plain (Tertiary sediments); 35,37,38-Coastal Plain (quartz-rich Quaternary
sediments); 36-Glauconitic Coastal Plain sediments.

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                 100 Miles
   Indoor Radon Screening
Measurements: Average (pCi/L)
                                                    0.0 to 1.9
                                                    2.0 to 4.0
                                                    4.1 to 10.0
                                                    10.1 to 32.6
                                                    Missing Data
                                                   -or < 5 measurements
                                        - f°r7?0™ties with 5 or more measurements in EPA

cateo            Services. Histograms in map legend show the number of counties in each

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          GEOLOGIC
      RADON POTENTIAL
    |    | LOW

         MODERATEWARIABLE
         HIGH
                                     • . . "jr
                                     • • •  •/•»
                                     •«••-V—v".  .
                                           .,- • •  • . * . • • . •  4 •
                                           ..-..'.•.•.•..- •.'..• .:-.
                                           •.'••*: ••.••»*.•*••'.•:•.
                                           I':-'.' -*.«-W'••:'.•
                                                                                          100
                                                                                miles
Figure 3.  Geologic radon potential of EPA Region 3. For more detail, refer to individual state
radon potential chapters.

-------
    rapid permeability.  Limited aereal radioactivity data for the Delaware Piedmont indicates that
    equivalent uranium is generally moderate (1.5-2.5 ppm).

    Coastal Plain
           Studies of radon and uidnium in Coastal Plain ^unents in New Jersey and Maryland
    suggest that glauconitic marine sediments equivalent to those in the northern portion of the
    Delaware Coastal Plain can cause elevated levels of indoor radon. Central New Castle County is
    underlain by glauconitic marine sediments of Cretaceous and Tertiary age that have moderate to
    locally high radon potential. Aerial radiometric data indicate that moderate concentrations of
    uranium occur in rocks and soils associated with the Piedmont and parts of the Coastal Plain of
    northern Delaware.  Chemical analyses of Cretaceous and Tertiary glauconitic marine sediments
    and fluvial sediments of the Columbia Formation performed by the Delaware geological survey
    indicate variable but generally moderate concentrations of uranium, averaging 1.89 ppm or greater.
    The permeability of soils in these areas is variable but generally moderate to high, allowing radon
    gas to move readily through the soil. Data for New Castle County from the State indoor radon
    survey shows that areas underlain by the Cretaceous fluvial sediments (not glauconitic) have lower
    average indoor radon levels than the glauconitic parts of the upper Cretaceous and lower Tertiary
    sequence to the south.  Kent County and all of Sussex County are underlain by quartz-dominated
    sands, silts, gravels, and clays with low radon potential.  These sediments are low in radioactivity
   and generally have a low percentage of homes with indoor radon levels greater than 4 pCi/L.

   MARYLAND

   Coastal Plain
          The Western Shore of Maryland has been ranked moderate to locally high in radon potential
   and the Eastern Shore has been ranked low in radon potential.  The Coastal Plain Province is
   underlain by relatively unconsolidated fluvial and marine sediments that are variably phosphatic
   and glauconitic on the Western Shore, and dominated by quartz in the Eastern Shore.
   Radioactivity in the Coastal Plain is moderate over parts of the Western Shore sediments,
   particularly in the Upper Cretaceous and Tertiary sediments of Prince George's, Anne Arundel,
   and northern Calvert counties. Moderate radioactivity also appears to be associated with the
   Cretaceous and Tertiary sediments of the Eastern Shore where these sediments are exposed in
   major drainages in Kent, Queen Anne's, and Talbot counties. Soil-gas radon studies in Prince
   George's County indicate that soils formed from the locally phosphatic, carbonaceous, or
   glauconitic sediments of the Calvert, Aquia, and Nanjemoy Formations can produce significantly
   high radon (average soil radon > 1500 pCi/L).  The Cretaceous Potomac Group had more
   moderate levels of soil radon, averaging 800-900 pCi/L, and the Tertiary-Cretaceous Brightseat
   Formation and Monmouth Group had average soil radon of 1300 pCi/L. Soil permeability on the
_JWestern ShoreuarieaLJfeom lo.w;.tQ.moderate with some-high permeability-in sandier soils,-Well-	
   developed clayey B horizons with low permeabmty are common. Indoor radon levels measured in
   the State/EPA Residential Radon Survey are variable among the counties of the Western Shore but
   are generally low to moderate. Moderate to high average indoor radon is found in most of the
   Western Shore counties.
         For this assessment we have ranked part of the Western Shore as high in radon potential
  including Calvert County, southern Anne Arundel County, and eastern Prince George's County.'
  This area has the highest radioactivity, high indoor radon, and significant exposure of Tertiary rock
                                            m-5     Reprinted from USGS Open-File Report 93-292-C

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 units.  The part of the Western Shore ranked moderate consists of Quaternary sediments with low
 radon potential, Cretaceous sediments with moderate radon potential, and lesser amounts of
 Tertiary sediments with high radon potential. The Quaternary sediments of the Eastern Shore have
 low radioactivity associated with them and are generally quartzose and thus low in uranium.
 Heavy-mineral concentrations within these sediments may be very local sources or uranium.
 Indoor radon appears to be generally low on the Eastern Shore with only a few measurements over
 4 pCi/L reported.

 Piedmont
        Gneisses and schists in the eastern Piedmont, phyllites in the western Piedmont, and
 Paleozoic metasedimentary rocks of the Frederick Valley are ranked high in radon potential.
 Sedimentary and igneous rocks of the Mesozoic basins have been ranked moderate in radon
 potential.  Radioactivity in the Piedmont is generally moderate to high. Indoor radon is moderate
 to high in the eastern Piedmont and nearly uniformly high in the western Piedmont. Permeability
 is low to moderate in soils developed on the mica schists and gneisses of the eastern Piedmont,
 Paleozoic sedimentary rocks of the Frederick Valley, and igneous and sedimentary rocks of the
 Mesozoic Basins. Permeability is moderate to high in the soils developed on the phyllites of the
 western Piedmont The Maryland Geological Survey has compared the geology of Maryland with
 the Maryland indoor radon data. They report that most of the Piedmont rocks, with the exception
 of ultramafic rocks, can contribute to indoor radon readings exceeding 4 pCi/L. Their data indicate
 that the phyllites of the western Piedmont have much higher radon potential than the schists in the
 east Ninety-five percent of the homes built on phyllites of the Gillis Formation had indoor radon
 measurements greater than 4 pCi/L, and 47 percent of the measurements were greater than 20
 pCi/L. In comparison, 80 percent of the homes built on the schists and gneiss of the Loch Raven
 and Oella Formations had indoor radon readings greater than 4 pCi/L, but only 9 percent were
 greater than 20 pCi/L.
       Studies of the phyllites in Frederick County show high average soil-gas radon (>1000
 pCi/L) when compared to other rock types in the county. Limestone and shale soils of the
 Frederick  Valley and some of the Triassic sedimentary rocks may be significant sources of radon
 (500-2000 pCi/L in soil gas).  Because of the highly variable nature of the Triassic sediments and
 the amount of area that the rocks cover with respect to the county boundaries, it is difficult to say
 with confidence whether the high indoor radon in Montgomery, Frederick, and Carroll counties is
 partly attributable to the Triassic sediments. In Montgomery County, high uranium concentrations
 in fluvial crossbeds of the upper Manassas Sandstone containing gray carbonaceous clay intraclasts
 and drapes have been documented. Similar lithologic associations are common in the upper New
 Oxford Formation. Black shales and gray sandstones of the Heidlersburg Member are similar to
 uranium-bearing strata in the Culpeper basin in Virginia and may be a source of radon.  Black
 shales in the overlying Gettysburg Formation may also be locally uranium rich. The lower New
 Oxford Formation, the lower Manassas Sandstonerthe lower Gettysburg Formation; and the Balls
 Bluff Siltstone in Maryland are not likely to have concentrations of uranium except where altered
 by diabase intrusives and/or faulted. The diabase bodies are low in radon potential.

Appalachian Mountains
       The Appalachian Province is divided into the Blue Ridge, Great Valley, Valley and Ridge,
 and Allegheny Plateau. Each of these areas is underlain by a distinct suite of rocks, with a
particular geologic radon potential. The Blue Ridge is ranked low in radon potential but may be
                                          ffl-6    Reprinted from USGSOpen-FDe Report 93-292-C

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  locally moderate to high.  The Catoctin volcanic rocks that underlie a significant portion of the Blue
  Ridge have low radioactivity, yield low soil radon and have low soil permeability. The quartzite
  and conglomerates overlying the Catoctin also have low radioactivity and low soil-gas radon.
  Further, the Pennsylvania Topographic and Geologic Survey calculated the median uranium
  content of 80 samples of Catoctin metabasalt and metadiabase to be less than 0.5 ppm. The
  Harpers Formation phyllite bordering the Catoctin volcanic rocks yields high soil-gas radon
  (>1000 pCi/L), has greater surface radioactivity than the surrounding rocks and is a potential
  source of radon.  The Precambrian gneiss that crops out in the Middletown Valley of the southern
  Blue Ridge appears" to have moderate radioactivity associated with it and yielded some high radon
  in soil gas. It is difficult, given the constraints of the indoor radon data, to associate the high
  average indoor radon in the part of Frederick County underlain by parts of this province with the
  actual rocks.  The Blue Ridge is provisionally ranked low in geologic radon potential, but this
  cannot be verified with the presently existing indoor radon data.
         Carbonates and black shales in the Great Valley in Maryland have been ranked high in
  radon potential. Radioactivity is moderate to high over the Great Valley in Washington County.
  Washington County has more than 100 indoor radon measurements, has an average indoor radon
  concentration of 8.1 pCi/L in the State/EPA Survey, with over half'of the readings greater than
  4 pCi/L.  To the north in Pennsylvania, carbonate rocks of the Great Valley and Appalachian
  Mountain section have been the focus of several studies and the carbonate rocks in these areas
  produce soils  with high uranium and radium contents that generate high radon concentrations. In
  general, indoor radon in these areas is higher than 4 pCi/L. Studies in the carbonates of the Great
  Valley in West Virginia suggest that the deepest, most mature soils have the highest radium and
  radon concentrations and generate moderate to high indoor radon. High radon in soils and high
  indoor radon in homes over the black shales of the Martinsburg Formation of the Great Valley
  were also measured in West Virginia.
         The Silurian and Devonian rocks of the Valley and Ridge have been ranked moderate to
  locally high in geologic radon potential. Indoor radon measurements are generally moderate to
  high in Allegany County.  Soil permeability is variable but is generally moderate. Radioactivity in
  this part of the Valley and Ridge is moderate to locally high.  The Tonoloway, Keyser, and Wills
  Creek Formations, and Clinton and Hamilton Groups have high equivalent uranium associated
  with them and the shales, limestone soils, and hematitic sands are possible sources of the high
  readings over these units.
         The Devonian through Permian rocks of the Allegheny Plateau are ranked moderate in
  geologic radon potential.  Indoor radon measurements are generally moderate to high.
  Radioactivity in the Allegheny Plateau is low  to moderate with locally high equivalent uranium
  associated with the Pocono Group and Mauch Chunk Formation.  Soil permeability is variable but
  generally moderate.

—PENNSYLVANIA	
  New England Province
        The New England Province is ranked high in geologic radon potential.  A number of
  studies on the correlation of indoor radon with geology in Pennsylvania have been done. The
  Reading Prong area in the New England Province is the most notable example because of the
  national publicity surrounding a particularly severe case of indoor radon.  These studies found that
  shear zones within the Reading Prong rocks enhanced the radon potential of the rocks and created
                                            m-7     Reprinted from USGS Open-FUe Report 93-292-C

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 local occurrences of very high uranium and indoor radon. Several of the rock types in the Reading
 Prong were found to be highly uraniferous in general and they are the source for high radon levels
 throughout much of the province.

 Piedmont
       The Piedmont is underlain by metamorphic, igneous, and sedimentary rocks of
 Precambrian to Mesozoic age that have generally moderate to high radon potential. Rock types in
 the metamorphic crystalline portion of the Piedmont that have naturally elevated uranium
 concentrations include granitic gneiss, biotite schist, and gray phyllite.  Rocks that are known
 sources of radon and have high indoor radon associated with them include phyllites and schists,
 such as the Wissahickon Formation and Peters Creek Schist, shear zones in these rocks, and the
 faults surrounding mafic bodies within these rocks.
       Studies in the Newark Basin of New Jersey indicate that the black shales of the Lockatong
 and Passaic Formations and fluvial sandstones of the Stockton Formation are a significant source
 of radon in indoor air and in water. Where these rock units occur in Pennsylvania, they may be the
 source of high indoor radon as well. Black shales of the Heidlersburg Member and fluvial
 sandstones of the New Oxford Formation may also be sources of locally moderate to high indoor
 radon in the Gettysburg Basin. Diabase sheets and dikes within the basins have low eU.  The
 Mesozoic basins as a whole, however, are variable in their geologic radon potential. The Narrow
 Neck area is distinctly low in radioactivity and Montgomery County, which is underlain almost
 entirely by Mesozoic basin rocks, has an indoor radon average less than 4 pCi/L.  Other counties
 underlain partly  by the Mesozoic basin rocks, however, have average indoor radon greater than
 4 pCi/L. The Newark basin is high in radon potential whereas the Gettysburg basin is low to
 locally moderate. For the purposes of this report the basins have been subdivided along the
 Lancaster-Berks county boundary.  The Newark basin comprises the Mesozoic rocks east of this
 county line.

Blue Ridge
       The Blue Ridge Province is underlain by metasedimentary and metavolcanic rocks and is
generally an area of low radon potential.  A distinct low area of radioactivity is associated  with the
province on the map, although phyllite of the Harpers Formation may be uraniferous.  Soils
generally have variable permeability.  The metavolcanic rocks in this province have very low
uranium concentrations. It is difficult, given the constraints of the indoor radon data, to associate
the high average indoor radon in counties underlain by parts of this province with specific rock
units. When the indoor radon data are examined at the zip code level, it appears that most of the
high indoor radon is attributable to the Valley and  Ridge soils and rocks. The conclusion is that the
Blue Ridge is provisionally ranked low in geologic radon potential although this cannot be verified
with the presently available indoor radon data.
Ridge and Valley and Appalachian Plateaus
       Carbonate rocks of the Great Valley and Appalachian Mountain section have been the focus
of several studies and the carbonates in these areas produce soils with high uranium and radium
contents and soil radon concentrations. In general, indoor radon in these areas is higher than
4 pCi/L and the geologic radon potential of the area is high, especially in the Great Valley where
indoor radon is distinctly higher on the average than in surrounding areas. Soils developed on
                                           ffl-8    Reprinted from USGS Open-File Report 93-292-C

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 limestone and dolomite rock at the surface in the Great Valley, Appalachian Mountains, and
 Piedmont are probably sources of high indoor radon.
        The clastic rocks of the Ridge and Valley and Appalachian Plateaus province, particularly
 the Ordovician through Pennsylvanian-age black to gray shales and fluvial sandstones, have been
 extensively cited in the literature for their uranium content as weU as their general uranium
 potential. It appears from the uranium and radioactivity data and comparison with the indoor radon
 data that the black shales of the Ordovician Martinsburg Formation, the lower Devonian black
 shales, Pennsylvanian black shales of the Allegheny Group, Conemaugh Group, and Monogahela
 Group, and the fluvial sandstones of the Devonian Catskill and Mississippian Mauch Chunk
 Formation may be the source of most moderate to high indoor radon levels in the Appalachian
 Plateau and parts of the Appalachian Mountains section.
        Only a few areas in these provinces appear to have geologically low to moderate radon
 potential. The Greene Formation in Greene County appears to correlate with distinctly low
 radioactivity. The indoor radon for Greene County averages less than 4 pCi/L for the few
 measurements available in the State/EPA survey.
        Somerset and Cambria Counties in the Allegheny Mountain section have indoor radon
 averages less than 4 pCi/L, and it appears that low radioactivity and  slow permeability of soils may
 be factors in the moderate geologic radon potential of this area. These two counties and most of
 the Allegheny Mountain section are underlain by Pennsylvanian-age sedimentary rocks. The
 radioactivity map shows low to moderate radioactivity for the Pennsylvanian-age rocks in the
 Allegheny Mountain section and much higher radioactivity in the Pittsburgh Low Plateau section.
 Most of the reported uranium occurrences in these rocks appear to be restricted to the north and
 west of the Allegheny Mountain section. Approximately half of the  soils developed on these
 sediments have slow permeability and seasonally high water tables.

 Coastal Plain
       Philadelphia and Delaware Counties, in the southeastern corner of Pennsylvania, have
 average indoor radon less than 4 pCi/L and have low radioactivity. Part of Delaware County and
 most of Philadelphia County are underlain by Coastal Plain sediments with low uranium
 concentrations.  Soils developed on these sediments are variable, but a significant portion are
 clayey with slow permeability.

 Glaciated Areas of Pennsylvania
       Radiometric lows and relatively lower indoor radon levels appear to be associated with the
 glaciated areas of the State, particularly the eastern portion of the Glaciated Low Plateau and
 Pocono Plateau in Wayne,  Pike, Monroe, and Lackawanna Counties. Glacial deposits are
 problematic to assess for radon. In some areas of the glaciated portion of the United States, glacial
 deposits enhance radon potential, especially where the deposits have high permeability and are
 derivedJromjirariiferous source-rocks.- In other portions of the glaciated United-Statesrglaeial	
 deposits blanket more uraniferous rock or have low permeability and corresponding low radon
potential. The northeastern corner of Pennsylvania is covered by the Olean Till, made up of 80-90
percent sandstone and siltstone clasts with minor shale, conglomerate, limestone, and crystalline
 clasts. A large proportion of the soils developed on this till have seasonally high water tables and
poor drainage, but some parts of the till soils are stony and have good drainage and high
permeability. Low to moderate indoor radon levels and radioactivity in this area may be due to the
 seasonally saturated ground and to the tills being made up predominantly of sandstones and
                                           m-9    Reprinted from USGS Open-File Report 93-292-C

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 siltstones with low uranium contents. A similar situation exists in the northwestern part of the
 State, which is covered by a wide variety of tills, predominantly the Kent Till, which contains
 mostly sandstone, siltstone, and shale clasts. Many of the soils in this area also have low
 permeabilities and seasonally high water tables. Where the tills are thinner, the western portion of
 the Glaciated Low Plateau has higher indoor radon and high radioactivity.

 VIRGINIA

 Coastal Plain
        The Coastal Plain of Virginia is ranked low in geologic radon potential. Indoor radon is
 generally low; however, moderate to high indoor radon can occur locally and may be associated
 with phosphatic, glauconitic, or heavy mineral-bearing sediments. Equivalent uranium over the
 Tertiary units of the Coastal Plain is generally moderate. Soils developed on the Cretaceous and
 Tertiary units are slowly to moderately permeable. Studies of uranium and radon in soils indicate
 that the Yorktown Formation could be a source for elevated levels of indoor radon. The
 Quaternary sediments generally have low eU associated with them. Heavy mineral deposits of
 monazite found locally within the Quaternary sediments of the Coastal Plain may have the potential
 to generate locally moderate to high indoor radon.

 Piedmont
       The Goochland terrane and Inner Piedmont have been ranked high in radon potential.
 Rocks of the Goochland terrane and Inner Piedmont have numerous well-documented uranium and
 radon occurrences associated with granites; pegmatites; granitic gneiss; monazite-bearing
 metasedimentary schist and gneiss; graphitic and carbonaceous slate, phyllite, and schist; and shear
 zones. Indoor radon is generally moderate but significant very high radon levels occur in several
 areas.  Equivalent uranium over the Goochland terrane and Inner Piedmont is predominantly high
 to moderate with areas of high eU more numerous  in the southern part. Permeability of soils
 developed over the granitic igneous and metamorphic rocks of the Piedmont is generally moderate.
 Within the Goochland terrane and Inner Piedmont,  local areas of low to moderate radon potential
 will probably be found over mafic rocks (such as gabbro and amphibolite), quartzite, and some
 quartzitic schists. Mafic rocks have generally low uranium concentrations and slow to moderate
 permeability in the soils they form.
       The Carolina terrane is variable in radon potential but is generally moderate. Metavolcanic
 rocks have low eU but the granites and granitic gneisses have moderate to locally high eU.  Soils
 developed over the volcanic rocks are slowly to moderately permeable. Granite and gneiss soils
 have moderate permeability.
     The Mesozoic basins have moderate to locally high radon potential. It is not possible to make
 any general associations between county indoor radon averages and the Mesozoic basins as a
 whole because of the limited extent of many the basins: However,: sandston*es~and siltstones of the"
 Culpeper basin, which have been lightly metamorphosed and altered by diabase intrusion, are
 mineralized with uranium and cause documented moderate to high indoor radon levels in northern
 Virginia. Lacustrine black shales and some of the coarse-grained gray sandstones also have
 significant uranium mineralization, often associated with green clay clasts and copper. Equivalent
 uranium over the Mesozoic basins varies among the basins. The Danville basin has very high eU
 associated with it whereas the other basins have generally moderate eU. This radioactivity may be
related to extensive uranium mineralization along the Chatham fault on the west side of the Danville
                                           m-10    Reprinted from USGS Open-File Report 93-292-C

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 basin. Localized high eU also occurs over the western border fault of the Culpeper basin. Soils
 are generally slowly to moderately permeable over the sedimentary and intrusive rocks of the
 basins.

 Valley and Ridge
       The Valley and Ridge has been ranked high in geologic radon potential but some areas have
 locally low to moderate radon potential. The Valley and Ridge is underlain by Cambrian dolomite,
 limestone, shale, and sandstone; Silurian-Ordovician limestone, dolomite, shale, and sandstone;
 and Mississippian-Devonian sandstone, shale, limestone, gypsum, and coal. Soils derived from
 carbonate rocks and black shales, and black shale bedrock may be sources of the moderate to high
 levels of indoor radon in this province. Equivalent uranium over the Valley and Ridge is generally
 low to moderate with isolated areas of high radioactivity. Soils are moderately to highly
 permeable. Studies of radon in soil gas and indoor radon over the carbonates and shales of the
 Great Valley in West Virginia and Pennsylvania indicate that the rocks and soils of this province
 constitute a significant source of indoor radon. Sandstones and red siltstones and shales are
 probably low to moderate in radon potential. Some local uranium accumulations are contained in
 these rocks.

 Appalachian Plateaus
       The Appalachian Plateaus Province has been ranked moderate in geologic radon potential.
 The plateaus are underlain by Pennsylvanian-age sandstone, shale, and  coal. Black shales,
 especially those associated with coal seams, are generally elevated in uranium and may be the
 source for moderate to high radon levels.  The coals themselves may also be locally elevated in
 uranium. The sandstones are generally low to moderate in radon potential but have higher soil
 permeability than the black shales. Equivalent uranium of the province is low to moderate and
 indoor radon is variable from low to high, but indoor radon data are limited in number.

 WEST VIRGINIA

Allegheny Plateau
       The Central Allegheny Plateau Province has moderate geologic radon potential overall, due
 to persistently moderate eU values and the occurrence of steep, well-drained soils. However,
 Brooke and Hancock counties, in the northernmost part of this province, have average indoor
radon levels exceeding 4 pCi/L.  This appears to be related to underlying Conemaugh and
 Monongahela Group sedimentary rocks which have elevated eU values in this area and in adjacent
 areas of western Pennsylvania.
       The Cumberland Plateau and Mountains Province has low radon potential. The eU values
 for the province are low except in areas of heavy coal mining, where exposed shale-rich mine
 waste~tends to'increaservalues. "Indoorfaddn levels aWfage less th^
       The Eastern Allegheny Plateau and Mountains Province has moderate radon potential
 overall. Locally high indoor radon levels are likely in homes on dark gray shales of Devonian age
 and colluvium derived from them in Randolph County. The southern part of this province has
 somewhat lower eU values and indoor radon averages.
                                          m-11    Reprinted from USGS Open-FUe Report 93-292-C

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Ridge and Valley Province
       The southern part of the Appalachian Ridge and Valley Province in West Virginia has
moderate radon potential overall. The eU signature for this province is elevated (> 2.5 ppm eU).
Locally high radon potential occurs in areas of deep residual soils developed on limestones of the
Mississippian Greenbrier Group, especially in central Greenbrier County, where eU values are
high. Elevated levels of radon may be expected in soils developed on dark shales in this province
or in colluvium derived from them.
       The northern part of the Appalachian Ridge and Valley Province in West Virginia has high
geologic radon potential. The soils in this area have an elevated eU signature.  Soils developed on
the Martinsburg Formation and on limestones and dolomites throughout the Province contain
elevated levels of radon and a very high percentage of homes have indoor radon levels exceeding
4 pCi/L in this province. Karst topography and associated locally high permeability in soils
increases the radon potential.  Structures sited on uraniferous black shales may have very high
indoor radon levels. Steep, well-drained soils developed on phylh'tes and quartzites of the Harpers
Formation in Jefferson County also produce high average indoor radon levels.
                                           m-12    Reprinted from USGS Open-File Report 93-292-C

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   PRELIMINARY GEOLOGIC RADON POTENTIAL ASSESSMENT OF WEST VIRGINIA
                                           by
                         James K. Otton and Linda C.S. Gundersen
                                 U.S. Geological Survey

INTRODUCTION

       This assessment of the radon potential of West Virginia is derived from geologic
information from publications of the West Virginia Geological Survey (especially Cardwell and
others, 1968), from publications of the U.S. Geological Survey, and from literature on the
geologic occurrence of radon. For a brief synopsis of the concepts and methodology used in this
report, please refer to the introductory chapter of this volume. Analyses of data gathered during a
radon survey in the winter of 1987-1988 by U.S. EPA and the West Virginia Department of
Health, and additional indoor radon data compiled from this study and vendor data by EPA
Region 3 (Noble and others, 1990) are included in this report. The National Atlas of the United
States of America provided much information on the geographic setting.  Soil descriptions are
developed from a map of West Virginia soils by the Soil Conservation Service (1979).
       This is a generalized assessment of geologic radon potential of rocks, soils, and surficial
deposits of West Virginia. 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 state, 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

GEOGRAPHIC SETTING

      Five physiographic regions are delineated in West Virginia: the Central Allegheny Plateau,
the Cumberland Plateau and Mountains, the Eastern Allegheny Plateau and Mountains, the
Southern Appalachian Ridge and Valley, and the Northern Appalachian Ridge and Valley (fig. 1).
      The Central Allegheny Plateau makes up the northwestern third of the State. It consists of
a dissected plateau that slopes downward to the Ohio River.  Greater than 80 percent of the area is
steeply sloping (greater than 25 percent) with relief ranging from 300- 1000 feet.
area is deeply dissected with steep slopes and narrow ridgetops. Greater than 80 percent of the
area is steeply sloping. Relief usually exceeds 1000 feet.
       The Eastern Allegheny Plateau and Mountains is a high plateau that is locally deeply
dissected to form mountainous areas. In the plateau areas gentle slopes (less than 10 percent)
occur but most of the area has steep slopes and relief that usually exceeds 1000 feet.
                                          IV-1    Reprinted from USGS Open-File Report 93-292-C

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        The Southern and Northern Appalachian Ridge and Valley are characterized by northeast-
  trending ridges and valleys with relief exceeding 1000 feet  Gently sloping areas are generally
  confined to the valleys.
        Precipitation ranges from 35-40 inches in the Appalachian Ridge and Valley areas, 45-60
  inches in the Eastern Allegheny Plateau and Mountains Province, and about 45 inches in the
  remainder of the State (fig. 2).
        Population distribution (fig. 3) and land use in West Virginia reflect in part the geology,
  topography, and climate of the State. In 1990 the population of West Virginia was 1,793,477,
  including 36 percent urban population. The average population density is approximately 77 per
  square mile. The climate is humid continental except for marine modification in the eastern
  panhandle.  West Virginia has distinct seasonal changes. The mean annual temperature ranges
  from52°Fto56°F.

  GEOLOGIC SETTING

        The Central Allegheny Plateau is underlain by generally flat-lying shale, siltstone,
  sandstone, and some limestone of Permian and Pennsylvanian age (fig. 4). The area is deeply
  dissected. Steep slopes are common and much of the area is covered by colluvium and landslides.
  Areas of open mine cuts and spoil piles occur in Harrison, Barbour, Monongalia, Marion, Taylor
  and other counties in the eastern part of this province.
        The Cumberland Plateau and Mountains is covered by sandstone, siltstone, shale and coal
  of Pennsylvanian age. Extensive underground and surface mining of coal has occurred in this
  province. The area is deeply dissected, steep slopes are common, and much of the area is covered
  by colluvium and landslides. Areas of open mine cuts and spoil piles occur throughout this
 province.
        The Eastern Allegheny Plateau and Mountains is underlain by shale, siltstone, sandstone,
  and some limestone of Pennsylvanian, Mississippian, and Devonian age. Underground and
  surface mining of coal occurs in a few areas. Colluvium derived from shale, siltstone and
 sandstone predominates throughout this province. Landslide areas occur in the southwestern half
 of this province. Areas of open mine cuts and spoil piles also occur in the southwestern half of
 this province.  Some areas of karst occur in the limestones that underlie this province (fig. 5).
        The Southern Appalachian Ridge and Valley is underlain by shale, siltstone, limestone, and
 sandstone of Mississippian, Devonian, Silurian, and Ordovician age.  These rocks have been
 folded and locally cut by thrust faults. Colluvium dominates the surficial materials.  Karst
 topography and associated caverns are common in areas underlain by limestone (fig. 5). Land
 subsidence caused by historical collapse of solution features has occurred in Greenbrier County
 (See figure 6 for location of counties discussed in this report.).
        The Northern Appalachian Ridge and Valley consists of parallel sandstone ridges separated
.liSJ^rowJI^loj^^	
 Devonian in age but Mississippian, Silurian, Ordovician, and Cambrian rocks also occur.  The
 Great Valley, a broad valley underlain mostly by limestone and shale, occupies much of Berkeley
 and Jefferson Counties.  Metamorphosed basalts in the Catoctin Formation occur along the
 southeastern edge of Jefferson County. Colluvium dominates most surficial materials except in the
 broad limestone valleys of Berkeley and Jefferson Counties where deep residuum has formed.
 Karst topography and associated caverns occur in areas underlain by limestone.
                                           IV-3    Reprinted from USGS Open-FUe Report 93-292-C

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                                                POPULATION (1990)
                                                   0 to 10000
                                               0  10001 to 25000
                                               E3  25001 to 50000
                                               II  50001 to 100000
                                               •  100001 to 207619
Figure 3. Population of counties in West Virginia (1990 U.S. Census data).

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                                                                                                     EXPLANATION

                                                                                                     Permian or Pennsylvania!! (230+ ml.
                                                                                                     yrs. ago). Cyclic sequences of
                                                                                                     sandstone, red beds, shale, limestone
                                                                                                     andcoaL

                                                                                                     Pennsylvania!! (280-310 ml. yrs. ago).
                                                                                                     Cyclic sequences of sandstone, shale.
                                                                                                     day. coal, and Brnestone.

                                                                                                     Uteslstlpplan (310-345 mil. yrs. ago).
                                                                                                     Limestone, red beds, shale and
                                                                                                     sandstone.

                                                                                                     Devonian (345-405 mi. yrs. ago). Red
                                                                                                     beds, shale, sandstone, limestone, and
                                                                                                     chert

                                                                                                     Silurian (405-425 mi. yrs. ago).
                                                                                                     Sandstone, shale. Bmestone, rock salt,
                                                                                                     and ferruginous beds.

                                                                                                     Ordovldan (425-500 ma. yrs. ago).
                                                                                                     Limestone, dolomite, sandstone, shale,
                                                                                                     and metabentonile.

                                                                                                     Cambrian (500-600 ml. yrs. ago).
                                                                                                     Limestone and dolomite, some
                                                                                                     sandstone and shale.

                                                                                                     Precambrlan (More than 600 mU. yrs.
                                                                                                     ago). Greenstone. Present only In
                                                                                                     extreme eastern Jefferson County.
Fig. 4-  Generalized bedrock geologic map of West Virginia.  From Erwin,  1969.

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       An aeroradioactivity map of the State (Duval and others, 1989) shows that the Central
 Allegheny Plateau generally ranges from 1.5-3.0 ppm elJ with the entire province averaging
 between 2.0 and 2.5 ppm eU (fig. 7).  Much of western Mason County and parts of Hancock,
 Brooke, and Ohio Counties ranges from 2.5-3.0 ppm eU. The Cumberland Plateau and
 Mountains and the Eastern Allegheny Plateau and Mountains ranges from 0.5 to 2.5 ppm eU with
 the two regions averaging between 1.0 and 1.5 ppm eU. Some areas of somewhat elevated eU in
 these areas may reflect the increased values associated with shale-rich coal mine wastes.  The two
 Appalachian Ridge and Valley provinces range from 0.5 to 3.5 ppm eU and average between 2.0
 and 2.5 ppm eU.  Elevated eU values (2.5-3.5 ppm) in the Ridge and Valley areas are associated
 with residual soils developed on Mississippian shale and limestone in Pocohontas, Greenbrier, and
 Monroe Counties (Greenbrier Group); with Devonian shale and limestone in Mineral, Hampshire,
 Grant, and Hardy Counties; and with Cambrian, Ordovician and Mississippian limestones in
 Morgan, Jefferson, and Berkeley Counties.
       A few, isolated uranium (U) occurrences and radioactive anomalies were found in West
 Virginia during uranium exploration in the 1970s (Jacob, 1975). A sample from an outcrop of the
 Mississippian Mauch Chunk sandstone in Webster Springs, Webster County, West Virginia,
 yielded 400 ppm U.  Radioactivity anomalies (maximum of 45 times background) occur in
 sandstones of the Mississippian Pocono Formation near Marlinton in Pocohontas County. A
 sample from one locality contained 160 ppm U and 1100 ppm thorium (Th). These anomalies are
 probably related to heavy mineral concentrations in the sandstone. Just east of Parkersburg, Wood
 County, uranium occurs in sandstone of the Permian Dunkard Group. Samples of sandstone
 containing fossil plant debris yielded 50-90 ppm U (Jacob, 1975).
       , Ordovician, Silurian, and Devonian dark gray to black shales occur in narrow outcrop belts
 in all counties expect Jefferson County in the Northern Appalachian Ridge and VaUey; in
 Pocohontas, Greenbrier, and Monroe Counties in the Southern Appalachian Ridge and Valley; and
 in Randolph County in the Eastern Allegheny Plateau and Mountains (fig. 8). These shales are
 relatively high in uranium content (> 2.5 ppm U) and locally generate radon in soil gas exceeding
 4000 pCi/L (Schultz and others, 1992). Soil-gas radon values exceeding 2000 pCi/L generally
 result in indoor values exceeding 4 pCi/L. Dark gray to black shales in West Virginia include or
 occur in the Ordovician Martinsburg Formation, Silurian Rochester Shale  (Clinton Group), the
 Devonian Needmore Shale (Onesquethaw Group), the Devonian Marcellus Formation, the
 Devonian Harrell Shale, and the Devonian Brallier Formation.  The uraniferous Marcellus Shale
 and underlying limestones in Onandaga County, New York, are a source of significant elevated
 indoor radon (Hand, 1988) and also generate high radon in West Virginia. Evidence suggests that
 uranium from the Marcellus has moved downward during weathering into  the underlying
 limestones, thus both the black shale and the subjacent limestones are a source of radon indoors.
 Uranium from uraniferous shales in West Virginia may also be redistributed by weathering to other
 units.
SOILS
       Most soils throughout West Virginia are poorly developed because weathered sedimentary
rock on the moderate to steep slopes across the State tends to continually move downhill under the
influence of gravity, forming colluvium. Slightly weathered soils generally tend to have uranium
and radium contained within the structure of the rock and mineral fragments, where radon formed
from radium decay has less of an opportunity to escape to soil pores. Deep, residual soils occur in
                                          IV-9    Reprinted from USGS Open-File Report 93-292-C

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Fig. 7- Aeroradiometric map of West Virginia and nearby areas. Patterns increase in ppm
     eU by 0.5 ppm increments. Contours are drawn at the 1.5 ppm and 2.5 pm eTJ
boundaries. Maximum values in this map area are 3.0-3.5 ppm eU. Map from Duval and
                                 others (1989).

-------

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the broader, gently sloped valleys of Berkeley and Jefferson Counties in the Northern Appalachian
Ridge and Valley. Lesser areas of deep, residual soils developed on limestone occur in the
Southern Appalachian Ridge and Valley. In deep residual soils, uranium and radium have
commonly been released from the mineral grains of the original rock and now are found on the
surfaces of soil grains. Radon more readily escapes from these mineral grains to soil pores than in
cases in which the radium is mostly contained deeper within mineral fragments.
       Except for the highest parts of the Eastern Allegheny Plateau and Mountains, all of West
Virginia lies within the mesic udic soil moisture-temperature regime. The high areas in the central
Allegheny Mountains lie within the frigid udic soil moisture-temperature regime (note: Frigid soils
have 0-8°C mean annual soil temperatures whereas mesic soils have 8-15°C mean annual soil
temperatures). Both frigid udic and mesic udic soils are very moist (56-96 percent pore saturation
in sandy loams, and 74-99 percent saturation in a silty clay loam) in the winter and are moderately
moist (44-56 percent saturation in sandy loams, and 58-74 percent in a silty clay loam) in the
summer (Rose and others, 1991). In places where soils are generally moderately moist to very
moist, soil moisture will tend to inhibit radon migration by diffusion and flow. However, steeply
sloped soils, in which water drains rapidly from the soil profile, are common in West Virginia. In
these soils, radon may migrate more readily and the radon potential of these steeply sloped areas is
increased.
       The Central Allegheny Plateau soils are typically sandy to clayey loams, usually with
abundant sandstone fragments and shale chips. Most soils are on moderately steep to very steep
slopes. Soils are generally acid, thin, and many soils in the central and southwestern part of the
province contain swelling clays (i.e., form shrink-swell soils). The more clayey soils have low
permeability and are often wet
       Soils of the Cumberland Plateau and Mountains are typically sandy to clayey loams usually
with abundant sandstone fragments and shale chips. All soils are on moderately steep to very steep
slopes. Soils are thin and commonly stony.  Soils on valley floors are subject to frequent
flooding.
       Soils of the Eastern Allegheny Plateau and Mountains include sandy to clayey loams
usually with abundant sandstone fragments and shale chips.  Soils are usually thin, and many are
stony. Clayey loams have low permeability and are often wet where slopes are gentle. Soils on
valley floors are subject to frequent flooding.
       la the Southern Appalachian Ridge and Valley, sandy to clayey loams and rock outcrops
occur on ridges. These soils are typically thin and are often stony. The valleys are characterized
by silty clay loams with abundant chips of noncalcareous shale and sandstone with smaller areas of
silty clay loams containing chips of calcareous shale and limestone. Some deep, red clayey soils
developed from limestone also occur.  Many soils on gentle slopes are wet and have low
permeability.
       The Northern Appalachian Ridge and Valley soils are variable.  Sandy to clayey loams and
rock outcrops occur on...ridges._TJ^se_sjDJfls.are tyjric^
soils have formed on ridge tops. Soils in the valleys are characterized by silty clay loams with
abundant chips of noncalcareous shale and sandstone, with smaller areas of silty clay loams
containing chips of calcareous shale and limestone. Deep, red clayey soils developed from
limestone occur in the valleys of Berkeley and Jefferson Counties. Soils on stream bottoms are
subject to frequent flooding.
                                           IV-12   Reprinted from USGS Open-File Report 93-292-C

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  INDOOR RADON DATA

         The West Virginia Department of Health and the U.S. EPA conducted a population-based
  survey of indoor radon levels in 1006 homes in West Virginia during the winter of 1987-88
  (Table 1; fig. 9). In figure 9, data are shown only for those counties with 5 or more data values.
  Geologic interpretations of population-based data must be made with caution because the measured
  houses are typically only from a relatively few population centers in a given county and the
  distribution of these houses do not reflect the variation in geology in the county.  For example, a
  county may have a relatively high radon potential on well-drained, uraniferous soils on hillslopes
  that occur over a widespread area, but if housing is generally located on poorly-drained soils with
  low uranium contents situated on the valley floor, a population-based survey for that area will
  contain relatively low indoor radon values.
         The maximum value recorded in the State/EPA Residential Radon Survey was 82.1 pCi/L
  in Greenbrier County (Table 1). Counties with indoor radon averages exceeding 4 pCi/L include
  Berkeley, Hampshire, Jefferson, Morgan, and Pendleton in the Northern Appalachian Ridge and
  Valley, Greenbrier in the Southern Appalachian Ridge and Valley, Tucker in the Eastern Allegheny
  Plateau and Mountains, and Brooke and Hancock in the northernmost part of the Central Alleehenv
  Plateau (Table 1).                                                                  6   3
         A summary of 6799 readings has been compiled by U.S. EPA Region 3 (Noble and
  others, 1990) by county and zipcode for West Virginia. Although these data are in part from
  nonrandom sources that are subject to sampling biases, the number of values in the dataset and the
  coverage of the urban centers and rural areas of the State is extensive. A detailed analysis of this
  dataset is beyond the scope of this report; however, these data confirm many of the observations in
  the population-based study. Values exceeding 100 pCi/L occur in Jefferson, Berkeley,
  Greenbrier, Marion, and Marshall Counties.  Counties in which more than 10 percent of the homes
  tested had indoor radon levels of 20 pCi/L or more include Jefferson, Berkeley, Morgan and
  Hampshire in the Northern Appalachian Ridge and Valley, Greenbrier in the Southern Appalachian
  Ridge and Valley, and Barbour, at the eastern edge of the Central Allegheny Plateau.
        Table 2 shows data from the State/EPA study and the study by Noble and others (1990) for
  counties, combined and summarized by geologic province. Note that the percentages of indoor
  radon values greater than 4 pCi/L reported by Noble and others (1990) are systematically higher
  than those of the State/EPA survey.  Values in indoor radon datasets compiled from volunteer data
  (data reported by homeowners or radon measuring companies to officials) are typically higher than
  controlled surveys because once a high value is reported in an area or neighborhood, nearby
  residences are commonly tested at a higher rate than would be if random testing was employed.
  These residences are often high for the same geologic, construction, or other reasons that the first
  reported value was high, so the data set would become biased toward higher indoor radon values.
  Note that the percentages are much higher for the Southern Appalachian Ridge and Valley in the
J^b!e_sMY.*?!LH.*eStot^^Ajta^Ttoj^ectea_W^iCTi»gEOTtiQnofhomesfrom  __   _
  Greenbrier County in the Noble study than in the State/EPA study. The geology of Greenbrier
  County favors  significantly elevated indoor radon.
                                          IV-13    Reprinted from USGS Open-File Report 93-292-C

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                                                                   Basement & 1 st Floor Rn
                                                                          OtotO
                                                                          11 to 20
                                                                          21 to 40
                                                                          41 to 60
                                                                          61 to 80
                                                                          81 to 100
                                                                          Missing Data
                                                                          (< 5 measurements)
                                                                          100 Miles
                                                                 Basement & 1st Floor Indoor Rn
                                                                 Average Concentration (pCi/L)
                                                            17JSSS3
                                                           19 KSSSSSXSSM
                                                                  4 M&
0.0 to 1.0
1.1 to 2.0
2.1 to 3.0
3.1 to 4.0
4.1 to 9.2
Missing Data
~(< 5"nTe^asuremerifsy
                                                                          100 Miles
Figure 9.  Screening indoor radon data from the EPA/State Residential radon Survey of West Virginia,
1988-89, 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.

-------
TABLE 1.  Screening indoor radon data from the State^PA Residential Radon Survey of
West Virginia conducted during 1989-90. Data represent 2-7 day charcoal canister
measurements from the lowest level of each home tested.
COUNTY
BARBOUR
BERKELEY
BOONE
BRAXTON
BROOKE
CABELL
CALHOUN
CLAY
FAYK1TE
GELMER
GRANT
GREENBRffiR
HAMPSHIRE
HANCOCK
HARDY
HARRISON
JACKSON
JEFFERSON
KANAWHA
LEWIS
LINCOLN
LOGAN
MARION
MARSHALL
MASON
MCDOWELL
MERCER
MINERAL
MINGO
MONONGALIA
MONROE
MORGAN
NICHOLAS
OHIO
PENDLETON 	 	 _
PLEASANTS
POCAHONTAS
PRESTON
PUTNAM
RALEIGH
RANDOLPH
NO. OF
MEAS.
21
19
15
15
2'.
43
:
/
2t
8
1(
18
12
34
9
37
11
13
108
15
11
16
36
18
7
8
20
15
10
20
20
13
16
47
	 8
6
18
31
20
38
25
MEAN
3.(
7.:
1.8
2.:
5.'.
l.(
0.9
2.8
l.(
2.1
2.9
8.2
5.7
4.4
1.3
2.4
2.1
9.2
1.9
2.2
1.5
1.2
1.7
3.0
2.5
1.1
2.8
3.5
1.3
2.4
2.1
4.7
2.3
3.4
—5.2-
1.4
1.8
3.1
1.5
1.5
2.4
GEOM
MEAN
2.:
4.(
O/
I/
3.5
1.1
0.8
l.<
0.'
1.2
1.5
2.4
3.8
2.6
1.0
1.2
1.9
5.9
1.3
1.3
1.1
0.9
1.3
1.9
1.6
0.9
1.7
2.4
1.0
1.2
1.4
2.7
1.6
2.1
— 2.6
0.9
1.0
1.7
0.8
1.0
1.4
MEDIAN
l.<
3.6
0.8
l.i
3.7
l.(
O.i
1.:
0.7
1.3
1.6
2.2
3.7
3.C
l.C
1.4
2.1
7.2
1.3
1.4
0.9
0.8
1.3
1.8
2.0
1.3
1.5
2.0
1.1
1.5
1.8
2.8
1.9
1.9
	 3.4.
0.9
1.3
1.5
0.9
1.1
2.1
STD.
DEV.
4.2
9.6
2.<
l.<
6.(
1.6
0.6
2.7
0.8
2A
2S
19.1
7.8
4.7
0.7
3.0
1.1
8.2
1.9
22
1.4
0.9
1.2
3.6
2.4
0.5
3.0
3.2
0.8
4.3
1.9
6.1
2.0
3.6
—63.
1.2
1.8
3.9
1.8
1.5
2.4
MAXIMUM
15.:
41.J
ll.(
7.;
25.(
6.'
1.5
8.(
3.2
7.C
8/3
82.1
29.S
20.8
2.4
14.6
4.6
27.4
13.5
8.2
5.4
3.5
4.8
13.9
7.3
1.5
12.7
12.0
3.0
20.4
7.0
229
6.9
14.1
	 19=7
3.4
7.2
15.8
6.7
6.8
9.9
%>4 pCi/L
24
47
13
13
40
12
0
29
0
25
30
33
33
38
0
22
9
69
g
13
9
0
6
17
14
0
30
33
0
5
10
38
19
26
38
0
11
16
10
8
12
%>20 pCi/L
0
«l
0
0

0
0
0
0
0
0
11
8
3
0
0
0
8
0
0
0
0
0
0
0
0
0
0
0
e
o
g
0
0
	 0
0
0
0
0
0
0

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TABLE 1 (continued).  Screening indoor radon data for West Virginia.
COUNTY
RITCHIE
ROANE
SUMMERS
TAYLOR
TUCKER
TYLER
UPSHUR
WAYNE
WEBSTER
WETZEL
WffiT
WOOD
WYOMING
NO. OF
MEAS.
8
6
11
11
6
8
7
16
5
12
3
44
19
MEAN
0.8
1.6
1.2
2.0
4.8
2.4
2.4
2.7
1.0
2.6
1.6
1.9
2.7
GEOM.
MEAN
0.7
1.2
1.0
0.9
2.7
1.6
1.7
1.6
0.8
1.4
0.8
1.2
1.4
MEDIAN
0.8
1.2
1.1
1.0
2.2
2.6
2.4
1.8
0.8
1.7
0.6
1.2
1.6
STD.
DEV.
0.5
1.2
0.8
2.8
6.9
1.4
1.6
2.7
0.6
3.2
2.1
2.6
3.2
MAXIMUM
1.4
3.7
3.1
9.8
18.7
4.1
4.7
10.8
1.6
12.1
4.0
16.4
13.7
%>4 pCi/L
0
0
0
9
17
13
14
19
0
17
0
14
21
%>20 pCi/L
0
0
0
0
0
0
0
0
0
0
0
0
0

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  TABLE 2. Indoor radon data from the State/EPA Residential Radon Survey and Noble and others
  (1990), grouped by geologic province.               ,.


                  State/EPA     State/EPA     State/EPA    Noble etal   Noble etal
  Province         no. of homes  arith. mean    %>4nri/T.   nn  r>fVinm»c a'^A^nin
Central All.
Plateau
Cumb.
Plat/Mtns
Eastern All.
Plateau
S. Appalachian
Ridge and Valley
N. Appalachian
Ridge and Valley
593
113
114
87
99
2.40
1.73
2.35
3.35
5.28
15.3
8.0
11.4
18.4
38.4
3576
339
461
449
1883
20.0
10.9
16.3
30.5
45.6
 GEOLOGIC RADON POTENTIAL

       Because steep, well-drained soils are common throughout West Virginia and soil eU values
 range from about 1.0 to 3.5 ppm, no county in the State can be expected to have buildings
 completely free from indoor radon values exceeding 4 pCi/L. Some areas of the State may have
 high average indoor radon levels and high percentages of homes exceeding 4 pCi/L, largely due to
 the physical and radiochemical properties of the soils underlying these areas.
       Carbonate rocks themselves are usually low in radionuclide elements, but the soils
 developed from carbonate rocks are commonly elevated in uranium and radium. When the
 carbonate minerals dissolve away, the soils are enriched in the remaining clay and iron oxides
 which collect impurities, including base metals, uranium, and radium.  The accumulation of
 uranium is strongly enhanced where the carbonate rocks are phosphatic because phosphatic
 carbonate rocks contain more uranium initially and the phosphate and associated uranium
 concentrate readily in the residual soils. Karst terrains that develop on carbonate rocks also
 enhance radon potential because the bedrock contains numerous solution openings that accumulate
 radon and increase the bedrock permeability. Soils derived from Cambrian-Ordovician carbonate
 rock units of the Valley and Ridge Province cause known indoor radon problems in eastern
 Tennessee (Goldsmith and others, 1983), western New Jersey, western Virginia, and central and
 eastern Pennsylvania (Greemanand-othersr1990,--Saehs-and others, 1982).	
       High levels of radon in son gas have been documented in deep, residual soils developed on
 Cambrian and Ordovician limestones in Berkeley and Jefferson Counties (Schultz and others,
 1992). These soils contain as much as 4 times the concentration of radium and 10 times the '
 concentration of uranium as the underlying bedrock. Such soils have developed over rocks of the
 Elbrook Formation, the Conococheague Formation, and the Beekmantown Group and locally
 contain soil-gas radon in  excess of 4,000 pCi/L. Twenty-two of 98 soil-gas samples taken at
homesites in these two counties exceeded 2000 pCi/L. These units also contain chert and cherty


                                         IV-17    Reprinted from USGS Open-File Report 93-292-C

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fragments in soils may contribute to high soil permeability.  Siltstone, fine-grained sandstone, and
dark gray shale of the Martinsburg Formation in these two counties contain elevated concentrations
of uranium and produce soils that also locally exceed 4000 pCi/L (Schultz and others, 1992).
Berkeley and Jefferson Counties have a high percentage of homes exceeding 4 pCi/L in the
State/EPA study (47.4 and 69.2 percent respectively) and in the study by Noble and others (1990;
49.2 and 52.4 percent respectively).
       Dark shales similar to those found in West Virginia are a source of high indoor radon in
Kentucky (Peake and Schumann, 1991). Glacially-derived soils with fragments of the uraniferous
Ohio shale are the principal cause of the high percentage of homes with indoor radon levels
exceeding 4 pCi/L (72-92 percent) and levels as high as 200 pCi/L indoors in the Columbus, Ohio
area (M. Hansen, written commun., 1988). Because of their high swelling clay content, soils
developed on many dark shales provide poor foundation conditions for structures and may locally
cause cracking of concrete. Structures sited on dark shales or colluvium containing abundant
fragments of dark shale are very likely to have elevated indoor radon levels, especially where
fractures increase the bedrock permeability and sloping topography tends to promote drainage and
keep the soils drier. Such structures may locally have radon levels exceeding 200 pCi/L indoors.

SUMMARY

       For the purpose of this assessment, West Virginia has been divided into five geologic
radon potential areas and each area assigned a Radon Index (RI) and a Confidence Index (CI) score
(TableS). These radon potential areas correspond to the physiographic regions (fig. 1). TheRIis
a semi-quantitative measure of radon potential based on geology, soils, radioactivity, architecture,
and indoor radon. The CI is a measure of the relative confidence of the RI assessment based on
the quality and quantity of the  data used to assess geologic radon potential (see the Introduction
chapter to this regional booklet for more information).
       The Central Allegheny Plateau has moderate geologic radon potential overall, owing to
persistently moderate eU values and steep, well drained soils. However, Brooke and Hancock
Counties, in the northernmost  part of this province, have average indoor radon levels greater than 4
pCi/L This appears to be related to underlying Conemaugh and Monongahela Group sedimentary
rocks which have elevated eU values (> 2.5 ppm) in this area and in adjacent areas of western
Pennsylvania.
       The Cumberland Plateau and Mountains have low radon potential. The eU values for the
province are low except in areas of heavy coal mining, where exposed shale-rich mine waste tends
to increase the radon potential. Indoor radon levels average less than 2 pCi/L in  most counties.
       The Eastern Allegheny Plateau and Mountains have moderate geologic radon potential
overall. Locally high indoor radon levels are likely on dark gray shales of Devonian age and
colluvium derived from them in Randolph County. The southern part of this province has
somewhat lower eU values and indoor radonavejrages are ajs_p_ somewhat lower..	,	
       The Southern Appalachian Ridge and Valley Province has moderate radon potential overall.
The eU signature for this province is elevated. Locally high radon potential occurs in areas of deep
residual soils developed on limestones of the Mississippian Greenbrier Group, especially in central
Greenbrier County where eU values are high. Elevated levels of radon may be expected in soils
developed on dark shales  in this province or in colluvium derived from them.
       The Northern Appalachian Ridge and Valley has high radon potential. The eU signature of
the soils is elevated. Soils developed on the Martinsburg Formation and on limestones and
                                          IV-18    Reprinted from USGS Open-File Report 93-292-C

-------
dolomites throughout the province contain elevated levels of radon—a very high percentage of
homes exceed 4 pCi/L in this province. Karst topography and the locally high permeability in soils
associated with it increases the radon potential. Structures sited on uraniferous black shales may
have very high indoor radon levels.  Steep, well-drained soils developed on phyllites and quartzites
of the Harpers Formation in Jefferson County also produce high average indoor radon levels.
       Uranium occurrences are rare but not unknown in West Virginia.  Where a structure is sited
over a uranium occurrence, indoor radon levels may be extreme, possibly exceeding 200 pCi/L.
       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 than assigned to the area as a whole.  Any local decisions about radon should
noj 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-19    Reprinted from USGS Open-File Report 93-292-C

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TABLE 3. Radon Index (RI) and Confidence Index (CI) for geologic radon potential areas of
West Virginia. See figure 1 for locations of areas.
                       Central
                   Allegheny Plateau
                 Cumberland Plateau
                   & Mountains
     FACTOR
RI
CI
RI
CI
                                Eastern Allegheny
                                 Plateau & Mts
RI
CI
INDOOR RADON
RADIOACTIVITY
GEOLOGY
SOIL PERM.
ARCHITECTURE
GFE POINTS
TOTAL
RANKING
2
2
2
2
2
0
10
MOD
3
3
2
3
-
-
11
HIGH
1
1
2
2
2
0
8
LOW
3
3
2
3
-
-
11
HIGH
2
2
2
2
2
0
10
MOD
3
3
3
3
-
-
12
HIGH
                 Southern Appalachian
                   Ridge & Valley
     FACTOR
RI
CI
                 Northern Appalachian
                   Ridge & Valley
RI
CI
INDOOR RADON
RADIOACTIVITY
GEOLOGY
SOIL PERM.
ARCHITECTURE
GFE POINTS
TOTAL
RANKING
2
2
3
2
2
0
11
MOD
3
3
3
3
.
-
12
HIGH
3
2
3
2
2
+2
14
HIGH
3
3
3
3
-
-
12
HIGH
RADON INDEX SCORING:

         Radon potential category
                  Point ran se
                          Probable screening indoor
                            radon average for area
         LOW                        3-8 points
         MODERATE/VARIABLE       9-11 points
         HIGH                       > 11 points

                           Possible range of points = 3 to 17

CONFIDENCE INDEX SCORING:
                                       <2pCi/L
                                       2-4pCi/L
                                       >4pCi/L
         LOW CONFIDENCE
         MODERATE CONFIDENCE
         HIGH CONFIDENCE
                        4-6  points
                        7-9  points
                       10 -12 points
                           Possible range of points = 4 to 12
                                       IV-20   Reprinted from USGS Open-File Report 93-292-C

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                          REFERENCES CITED IN THIS REPORT
        AND GENERAL REFERENCES PERTAINING TO RADON IN WEST VIRGINIA

  Cardwell, D. H, Erwin, R.B., and Woodward, H.P., 1968, Geologic map of West Virginia:
        West Virginia Geological and Economic Survey map, scale 1:250,000.

  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.

  Erwin, R.B., 1969, Geologic map of West Virginia: Morgantown, West Virginia Geological and
        Economic Survey, 1 plate.

  Facts on File, Inc. 1984, State maps on file.

  Goldsmith, W.A., Poston, J.W., Perdue, P.T., and Gibson,  M.O., 1983, Radon-222 and
        progeny measurements in "typical" east Tennessee residences: Health Physics, v. 45, n. 1,
        p.81-88.

  Greeman, D.J., Rose, A.W., and Jester, W.A., 1990, Form and behavior of radium, uranium,
        and thorium in central Pennsylvania soils developed from dolomite: Geophysical Research
        Letters, v. 17, p. 833-836.

  Hand, Bryce M., 1988, Radon in Onondaga County, New York: Paleohydrogeology and
        redistribution of uranium in Paleozoic sedimentary rocks: Geology, v. 16, p. 775.

  Jacob, A. F., 1975, Reconnaissance for uranium in Paleozoic rocks in the Appalachian Basin, in
        Craig, L.C., Brooks, R.A., and Patton, P.C., eds.,  Abstracts of the 1975 uranium and
        thorium research and resources conference: U.S. Geological Survey Open-file Report
        75-595, p. 23-24.                                                      V

 Noble, John, Coyle, Francis, and Erfer, Harold, 1990, West Virginia radon, statistical summary
        of readings, October 1990: Philadelphia, PA, U.S. Environmental Protection Agency,
        27 p.

 Peake, R.T., and Schumann, R.R., 1991, Regional radon characterizations, 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. 163-175.

 Rose, A.W., Ciolkosz, E.J., and  Washington, J.W.,  1991, Effects of regional and seasonal
       variations in soil moisture and temperature on soil gas radon, in The 1990 International
	Symposium~on Radon and Radon Reduction Technology, ProceedingsrVolr3:—
           —	— — _-____. v_v^^ j ^^ j. ^*w*^^*W*AA«.fc4Jj  J \J±+ &/•
       Symposium Poster Papers: Research Triangle Park, N.C., U.S. Environmental Protection
       Agency Rept. EPA600/9-91-026c, p. 6-49--6-60.

 Sachs, H.M., Hernandez, and Ring, J.W., 1982, Regional geology and radon variability in
       buildings: Environment International, v. 8, p. 97.
                                         IV-21   Reprinted from USGS Open-File Report 93-292-C

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Schultz, A., Wiggs, C.R., and Brower, S.D., 1992, Geologic and environmental implications of
       high soil-gas radon concentrations in the Great Valley, Jefferson and Berkeley Counties,
       West Virginia, in Gates, A.E., and Gundersen, L.C.S., eds., Geologic controls on radon:
       Geological Society of America Special Paper 271, p.29-44.

Soil Conservation Service, 1979, General Soil Map, West Virginia: Washington, D.C., U.S.
       Department of Agriculture, Soil Conservation Service, 1 plate, Scale 1:750,000.

West Virginia Geological and Economic Survey, 1979, Limestone outcrops and probable area
       underlain by rock salt and natural brine in West Virginia: West Virginia Geological and
       Economic Survey map, 1 plate.
                                          IV-22    Reprinted from USGS Open-File Report 93-292-C

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                              EPA's Map of Radon Zones


         The USGS1 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 screening
  potential between  2 pCi/L and 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., 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. (See Part I  for more
  details.)
  WEST VIRGINIA MAP OF RATVW

        The West Virginia Map of Radon Zones and its supporting documentation (Part IV of
  this report) have received extensive review by West Virginia geologists and radon program
  experts.  The map for West Virginia 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.
        Several West Virginia counties do not strictly follow the methodology for adapting
  geologic provinces to county boundaries.  EPA and the West Virginia Department of Health
  have designated Hancock, Brooke, Ohio, Wetzel, Monongalia, Marshall, Preston, Greenbrier
  Mercer, Summers, Monroe, and Pocahontas counties as Zone 1. Although most areas of these
  counties have moderate geologic radon potential, supplemental indoor radon data  for these
  counties estimate that significant percentages of homes are above 4 pCi/L.
        Although the  information provided in Part IV of this report -- the  State chapter entitled
  "Preliminary Geologic Radon Potential Assessment of West Virginia" -- 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
...EJL.^VrAlE_DJ.N_PP_OR RADONJSjq TEST.  Contact the Region 3 EPAofficepr the.  	
 West Virginia radon program for information on testing and fixing homes. Telephone
 numbers and addresses can be found in Part II of this report.
                                          V-l

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