United States
Environmental Protection
Agency
Air and Radiation
(6604J)
402-R-93-036
September 1993
-8-EPA EPA's Map of Radon Zones
KANSAS
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EPA'S MAP OF RADON ZONES
. "' ' .. -KANSAS -
' ' ' RADON DIVISION - ,:..' ,, _-
OFFICE OF RADIATION AND INDOOR AIR
U.S. ENVIRONMENTAL PROTECTION AGENCY
SEPTEMBER, 1993
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ACKNOWLEDGEMENTS.
This document was prepared by the U.S. Environmental Protection Agency's (EPA's)
Office of Radiation and Indoor Air (ORIA) in conjunction with the U.S. Geological Survey
(USGS) Sharon W. White was the EPA project manager. Numerous other people in ORIA
were instrumental in the development of the Map of Radon Zones, including Lisa Ratcliff,
Kirk Maconaughey, R. Thdmas Peake, Dave Rowson,.and Steve Page.
EPA would especially like to acknowledge the outstanding effort of the USGS
radon team Linda Gundersen, Randy Schumann, Jim Otton, Doug Owen, Russell
Dubiel, Kendell Dickinson, and Sandra Szarzi -- in developing the technical base for the
Map of Radon Zones. r
ORIA would also like to recognize the efforts of all the EPA Regional Offices in
coordinating the reviews with the State programs and the Association of American State
Geologists (AASG) for providing a liaison with the State geological surveys. In addition,
appreciation is expressed to all of the State radon programs and geological«sur«eys for their
technical input and review of the Map of Radon Zones.
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TABLE OF CONTENTS
I. OVERVIEW
II. THE USGS/EPA RADON POTENTIAL
ASSESSMENTS:INTRODUCTION
III. REGION 7 GEOLOGIC RADON POTENTIAL
SUMMARY
V. PRELIMINARY GEOLOGIC RADON POTENTIAL
ASSESSMENT OF KANSAS
V. EPA'S MAP OF RADON ZONES - KANSAS
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OVERVIEW
Sections 307 and 309 of the 1988 Indoor Radon 'Abatement Act (IRAA) direct EPA to
identify, areas of the United States that have the potential to produce elevated levels of radon.
EPA, the U.S- Geological Survey (USGS), and the Association of American State Geologists
(AASG) have-worked closely over the past several years to produce a series of maps anS
documents which address these directives. The EPA Map of Radon Zones is a compilation of
that work and fulfills the requirements of sections 307 and 309 of IRAA. The-Map of Radon
Zones identifies, on a county-by-county basis, areas of the U.S. that have the highest potential
for elevated indoor radon levels (greater than 4 pCi/L).
The Map of Radon Zones is designed to assist national, State and. local governments
and organizations to target their radon program activities and resources. It is also intended to
help building code officials determine areas that are the highest priority for adopting radon-
resistant building practices. The Map of Radon Zones should not be used to determine if
individual homes in any given area need to be tested for radon. EPA recommends that all
homes be tested for radon, regardless of geographic location or the zone designation of
the county in which they are located.
This .document provides background information concerning the development of'the
Map of Radon Zones. It explains the purposes of the map, the approach for developing the
map (including the respective roles of EPA and USGS), the data source's^used, the conclusions.
and confidence levels developed for the prediction of radon potential, and the review process
that was conducted to-finalize this effort, , . . "'"*
BACKGROUND
Radon (Rn222) is a colorless, odorless, radioactive gas. It comes from the natural
decay of uranium that is found in nearly all soils. ,It typically moves through the ground to
the air above and into homes and other buildings through cracks and openings in the
foundation. Any home, school or workplace may have a radon problem, regardless of
whether it is new or old, well-sealed or drafty, or with or without a basement. 'Nearly one out
of every 15 homes in the U.S. is estimated to have elevated annual average levels Of indoor
radon. ' ' '. , - ' """" . "'"* , ".
Radon first gained national attention in early 1984, when extremely high levels of
indoor radon were found in areas of Pennsylvania, New Jersey, and New York, along the
Reading Prong-physiographic province. EPA established a Radon Program in 1985 to assist
States and homeowners, in reducing their risk of lung cancer from indoor radon.
Since 1985; EPA and USGS have been'working together to continually increase our
understanding of radon sources and the migration' dynamics that cause elevated indoor radon
levels. Early efforts resulted in the 1987 map entitled "Areas with Potentially High Radon
Levels." This map vwas based on limited geologic information'only because few indoor radon
measurements were available at the time. The development of EPA's Map of Radon Zones
and its technical foundation, USGS! National Geologic Radon Province Map, has been based
on additional information from six years of the State/EPA Residential Radon. Surveys,
independent State residential surveys, and continued expansion of geologic and geophysical
1 information,,particularly the dath from the National Uranium Resource Evaluation project
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Purpose of the »Map of Radon Zones
EPA's Map of Radon Zones (Figure 1) assigns each of the 3141 counties in the
United States to one of three zones:
o Zone 1 counties have a predicted average indoor screening level > than
4 pCi/L
o Zone 2 counties have a predicted average screening level > 2 pCi/L and
< 4 pCi/L
o Zone 3 counties have a predicted average screening level < 2 pCi/L
The Zone designations were determined by assessing five factors that are known to be
important indicators of radon potential: indoor radon measurements, geology, aerial
radioactivity, soil parameters, and foundation typesl
The predictions of average screening levels in each of the Zones is an expression of
ifldoiLpotential in the lowest liveable area of a structure. This map is unable to estimate
actual exposures to radon. EPA recommends methods for testing and fixing individual homes
based on an estimate of actual exposure to radon. For more information on testing and fixing
elevated radon levels in homes consult these EPA publications: A Citizen's Guide to Radon,
the Consumer's Guide (o Radon Reduction and the Howe Buyer's and Seller's Guide to
Radoti, ' ,
EPA believes that States, local governments and other organizations can achieve
optimal risk reductions by targeting resources and program activities to high radon potential
areas. Emphasizing targeted approaches (technical assistance, information and outreach
efforts, promotion of real estate mandates and policies and building codes, etc.) in such areas
addresses the greatest potential risks first. ,
EPA also believes that the use of passive radon control systems in the construction of
new homes in Zone 1 counties, and the activation of those systems if necessitated by- follow-
up testing, is a cost effective approach to achieving significant radon risk reduction.
The Map of Radon Zones and its supporting documentation establish no regulatory
requirements. Use of this map by State or local radon programs and building code officials is
voluntary. The information presented on the Map of Radon Zones and in the supporting
documentation is not applicable to radon in water.
Development of the Map of Radon -Zones
The technical foundation for the Map of Radon Zones is the USGS Geologic Radon
Province Map. In order to examine the radon potential for the United States, the USGS
began by identifying approximately 360 separate geologic provinces for the U.S. The
provinces are shown on the USGS Geologic Radon Province Map (Figure-2). Each of the
geologic provinces was evaluated by examining the available data for that area: indoor radon
measurements, geology, aerial radioactivity, soil parameters, and foundation types. As stated
previously, these five factors are considered to, be of basic importance in assessing radon
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Figure 1
EPA Map of Radon Zones
Zone designation for Puerto Rtco ss tinaef d&v&lopftt<&m.
LEGEND
Zone 1
Zone 2
Zone 3
Guam- Preliminary Zone designation, j*^ The purpose of (his. map is lo assist National, State and local organizations to target their resources and to Implement radon-resistant building codes.
This map is not Mended to be used to~determ!ne if a home in a given zone should be tested for radon. Homes with elevated levels of radon have"been found
in oil three zones. All homes should be tested, regardless of "geographic location;, , . .
IMPORTANT; Consult fft'e EPA Map of Radon Zones document (EPA.-402-R-S3-07t). before using- this 'map. This 'document contains information on radon potential variations within counties, -
. £ft4"dto recommends fool this mop be supptemiWtterf Wlrt any available local data in order to further understand and predict the radon potent/a! of a specific area, .
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Figure 2
GENERALIZED GEOLOGIC RADON POTENTIAL OF THE UNITED STATES
by the U.S. Geological Survey
Scale
Continental United States
and Hawaii
500
Geologic Radon
Potential
(Predicted Average
Screening Measurement)
LOW (< 2 pCI/L)
MODERATE/VARIABLE
(2-4pCI/L)
HIGH (>4pCI/L)
Miles
6/93
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potential and some data are available for each of these factors in every geologic province. The
province boundaries do not coincide with political borders (county and state) but define areas
of general radon potential. The five factors were assigned numerical values, based on an
assessment pf their respective contribution to radon potential, and a confidence-level was
assigned to each contributing variable. The approach used by USGS/to .estimate the radon
potential for each province is described in Part II of this document. ,
EPA subsequently developed the Map of Raciun Zones by extrapolating iVom the,
province level to the county level so that all counties in the U.S. were assignee! to "one of
three radon zones. EPA assigned each county to a given zone based on its provincial radon
potential. For example, if a county is located within a geologic province that has ajpredicted
average screening level greater than 4 pCi/L, it was assigned to Zone 1". Likewise, counties
located in provinces with predicted average screening levels' > 2 pCi/L and < 4 pCi/L, and
less than 2 pCi/L, were assigned to Zones 2 and 3, respectively.
If the boundaries of a county fall in more than one geologic province, the county was
assigned to a zone based on the predicted radon potential of the province in which most of
the area lies. For example, if three different provinces cross .through a given county, the
county was assigned to the zone representing the radon potential of the province containing
most of the county's land area. (In this case, it is not technically correct to say that the
predicted average screening level applies to the entire county since the county falls-in
multiple provinces with differing radon potentials.) ' ,
Figures 3 and 4 demonstrate an example^ of how EPA extrapolated,tfhe county zone
designations/for Nebraska from the USGS geologic province map for the State. As figure 3 -
shows, USGS has identified 5 geologic provinces for Nebraska. Most of the counties are
extrapolated "straight" from their corresponding provinces, but there are counties "partitioned"
by several provinces for example, Lincoln County. .Although Lincoln county falls in
multiple provinces, it was assigned to Zone 3 because most of its area falls in the province
with the lowest radon potential. ,
It is important to note that EPA's extrapolation from the province level to the
county level may mask significant "highs"/and "lows" within specific counties. In other.
words, within-county variations in radon, potential are not shown on the Map of Radon
Zones. EPA recommends that users who may need to address specific withifi-county
variations in radon potential (e.g.» local government officials considering the
implementation of radon-resistant construction codes) consult USGS' -'Geologic Radon
Province Map and the State chapters.provided with this map for more detailed
information, as well as any locally available data.
Map Validation * . ~ , ^ '''''
The Map of Radon Zones is intended to represent a preliminary assessment of radon
potential for the entire United States. The factors that are used in this effort indoor radon
data, geology, aerial radioactivity, soils, and foundation type are basic indicators for radon
potential. It is important to note, .however, that the map's county zone designations are not
"statistically valid" predictions due to the nature of the data available for these 5 factors at the
county level. In order to validate the map in light of this lack of statistical confidence, EPA
conducted a number of analyses. These analyses have helped EPA to identify;the best
situations in which to apply the map; and its limitations.
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Figure 3
Geologic Radon Potential Provinces for Nebraska
Lincoln County
Bill
Uoitt itt
Low
Figure 4
NEBRASKA - EPA Map of. Radon Zones
Lincoln County
Zoat 1 Zone 2 Zone 3
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One such analysis involved comparing county zone designations to indoor radon
measurements from the State/EPA Residential Radon Surveys (SRRS). Screening averages
for counties with at least 100 measurements were compared to the counties' predicted radon
potential as indicated by the Map of Radon Zones. EPA found that 72% of the county
screening averages were correctly reflected by the appropriate zone designations on the Map.
In all other cases, they only differed by 1 zone: , .
Another accuracy analysis used the annual average data from the National Residential
Radon Survey (NRRS). The NRRS indicated that approximately 6 million homes in the
' United States have annual averages greater than or equal to 4 pCi/L. By cross checking the
county location of the approximately 5,700 homes which participated in the survey, their
radon measurements, and the zone designations for these counties, EPA found that
.approximately 3.8 million homes of the 5,4 million homes with radon levels greater than or
equal to 4 pCi/L will be found in counties designated as Zone 1. A random sampling of an
.equal number of counties would have only found approximately 1.8 million homes greater
than 4 pCi/L. In other .words, this analysis indicated that the map approach is three times
more efficient at identifying high radon areas than random selection of zone designations.
Together, these analyses show that the approach EPA used to develop the Map of
Radon Zones is. a reasonable one. In addition, the Agency's confidence is enhanced by results
of the extensive State review process the map. generally agrees with the States' knowledge
of and experience in their own jurisdictions. However, the accuracy analyses highlight two
important points: the fact that elevated levels will be found in. Zones 2 and 3, and that there,
will be significant numbers'of homes with lower indoor radon levels in all of the Zones. For
these reasons, users of the Map of Radon Zones need to supplement the Map with locally
available data whenever possible. Although all known "hot spots", i.e., localized areas of
consistently elevated levels, are discussed in the State-- .
specific chapters, accurately defining the boundaries of the "hot spots" on this scale of map is
not possible at this time. Also, unknown "hot spots" do exist. .,
The Map of Radon Zones is intended to be a starting point for characterizing radon
potential because our knowledge of radon sources and transport is always growing.^ Although
this effort represents the best data available at this time, EPA will continue to study these
parameters and others such as house construction,/ventilation features and meteoroBgy factors
in order to better characterize the presence of radon in U.S .homes, especially in high, risk,
areas. These efforts will eventually assist EPA in refining and revising the conclusions of the
Map of Radon Zones. And although this map is most appropriately used as a targeting tool
by the aforementioned audiences the Agency encourages all residents to test their homes
for radon, regardless of geographic location or the zone designation of the county in
which they live. Similarly, the Map of Radon Zones should not to be used in lieu of
testing during real estate transactions.
Review Process , <
The Map of Radon Zones has undergone extensive review,within EPA and outside the
Agency. The Association of American State Geologists (AASG) played an integral role in
this review process. The AASG individual State geologists have reviewed their State-specific
information, .the USGS Geologic Radon Province Map, and other materials for their geologic
content and consistency. /
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In addition to each State geologist providing technical comments, the State radon
offices were asked to comment on their respective States' radon potential evaluations. In
particular, the States were asked to evaluate the data used to assign their counties to specific
zones. EPA and USGS worked with the States to resolve any issues concerning county zone
designations. In a few cases, States have requested changes in county zone designations. The
requests were based on additional data from the State on geology, indoor radon
measurements, population, etc. Upon reviewing the data submitted by the States, EPA did
make some changes in zone designations. These changes, which do not strictly follow the
methodology outlined in this document, are discussed in the respective State chapters.
EPA encourages the States and counties to conduct further research and data collection
efforts to refine the Map of Radon Zones. EPA would like to be kept informed of any
changes the States, counties, or others make to the maps. Updates and revisions will be
handled in a similar fashion to the way the map was developed. States should notify EPA of
any proposed changes by forwarding the changes through the Regional EPA offices that are
listed in Part II. Depending on the amount of new information that is presented, EPA will
consider updating this map periodically. The State radon programs should initiate proper
notification of the appropriate State officials when the Map of Radon Zones is released and
when revisions or updates are made by the State or EPA.
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THE USGS/EPA RADON POTENTIAL ASSESSMENTS: AN INTRODUCTION
' ' . ' .v '.. b>! ' ':' '
Linda C.S. Gundersen and R. Randall Schumann , -s
U.S. Geological Survey
and
, . Sharon W. White
U.S. Environmental Protection Agency . '
/ .
BACKGROUND . .
The Indoor Radon Abatement Act of 1988 (15 U.S.C. 2661-2671) directed the U.S.
Environmental Protection Agency (EPA) to identify areas of the United States, that have the
potential to produce harmful levels of indoor radon. These characterizations were to be based.
on both geological data and on indoor radon levels in homes and other structures. The EPA
also was. directed to develop model standards'and techniques for new building construction
that would provide adequate prevention or mitigation of radon entry. As part of an
Irjterageney Agreement between the EPA and the U.S. Geological Suryey (USGS),, the USGS
has prepared radon potential estimates for the United States. This report ,is ©ne of ten
', booklets that document this effort. The purpose and intended use of these reports is to help
identify areas where states can target their radon program resources, to provide guidance in
selecting the most appropriate building code options for areas, and to provide'geoMal
information on radon and geology for each state for federal, state, and municipal officials
dealing with radon issues. These reports are not intended to be used as a substitute for .
indoor radon testing, and they cannot and should not be used to estimate or predict the
indoor radon concentrations of individual homes, building sites, or housing tracts. Elevated
levels of indoor radon have been found in "every State, and EPA recommends that all homes
be tested for indoor radon, '. t., .u
Booklets detailing the radon potential assessment for the U.S. have been developed'for
each State. USGS geologists are the authors of the geologic radon potential booklets. Each'
booklet consists of several components, the first being an overview to the mapping project
(Part I), this introduction to the USGS assessment (Part II), including a general discupsix>ri of
radon (occurrence, transport,, etc.), and details concerning the types of data used. The third
component is a summary chapter outlining the general geology and geologic radon potential
of the EPA Region (Part III). The fourth component is an individual chapter for each state
(Par,t IV). Each state chapter discusses the state's specific geographic setting, soils, geologic .
setting, geologic "radon potential, indoor radon data, and a summary outliningvthe radon
potential rankings of geologic areas in the state'. A variety of maps are presented in each
chaptergeologic, geographic, population, soils, aerial radioactivity, and indoor radon data by
county. Finally, the booklets contain EPA's map, of radon zones for each state and an
accompanying description (Part V). ' .
Because of constraints on the scales of maps presented in these reports^and because the
smallest .units used to present the indoor radpp data are counties, some"generalizations have
been made in order to estimate the radon potential of each area. Variations in geology, soil
characteristics, climatic factors, homeowner lifestyles^ and other factors that influence radon
concentrations can be quite large within any particular geologic area, so these reports cannot
be used to estimate or predict the indoor radon concentrations of individual hom'es or housing
, .. II-1 Reprinted from USGS Open-File Report 93-292
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tracts. Within any area of a given geologic radon potential ranking, there are likely to be
areas where the radon potential is lower or higher than that assigned to the area as a whole,
especially in larger areas such as the large counties in some western states.
In each state chapter, references to additional reports related to radon are listed for the
state, and the reader is urged to consult these reports for more detailed information. In most
cases the best sources of information on radon for specific areas are state and local
departments of health, state departments responsible for nuclear safety or environmental
protection, and 0.S. EPA regional offices. More detailed information on state or local
geology may be obtained from the state geological surveys. Addresses and telephone
numbers of state radon contacts, geological surveys, and EPA regional offices are listed in
Appendix C at the end of this chapter.
RADON GENERATION AND TRANSPORT IN SOILS ,
Radon %(3;2Rn) is produced from the radioactive decay of radium ("'Ra), which is, in turn,
a product of the decay of uranium (338TJ) (fig. 1). The half-life of 3MRn,is 3.825 days. Other
isotopes of radon occur naturally, but, with the exception of thoron (BORn), which occurs in
concentrations high enough to be of concern in a few localized areas, they are less important
in terms of indoor radon risk because of their extremely short half-lives and less common
occurrence. In general, the concentration and mobility of radon in soil are dependent on
several factors, the most important of which are the soil's radium content and distribution,
porosity, permeability to gas movement, and moisture content. These characteristics are, in
turn, determined by the soil's parent-material composition, climate, and the soil's age or
maturity. If parent-material composition, climate, vegetation, age of the soil, and topography .
are known, the physical and chemical properties of a soil in a given area can be predicted.
As soils form, they develop distinct layers, or horizons, that are cumulatively called the
soil profile. The A horizon is a surface or near-surface horizon containing a relative
abundance of organic -matter but dominated by mineral matter. Some soils contain an E
horizon, directly below the A horizon, that is generally characterized by loss of clays, iron, or
aluminum, and has a characteristically lighter color than the A horizon. The B horizon
underlies the A or E horizon. Important characteristics of B horizons include accumulation of
clays, iron oxides, calcium carbonate or other soluble salts, and organic matter complexes. ,In
drier environments, a horizon may exist within or below the B horizon that is dominated by
calcium carbonate, often called caliche or calcrete. This carbonate-cemented horizon is
designated the K horizon in modern soil classification schemes. The C horizon underlies the
B (or K) and is a zone of weathered parent material that does not exhibit characteristics of A
or B horizons; that is, it is generally not a zone of leaching or accumulation. In soils formed
in place from the underlying bedrock, the C horizon is a zone of unconsolidated, weathered
bedrock overlying the unweathered bedrock.
The shape and orientation of soil particles (soil structure) control permeability and affect
water movement in the soil. Soils with blocky or granular structure have roughly equivalent
permeabilities in the horizontal and vertical directions, and air and water can infiltrate the soil
relatively easily. However, in soils with platy structure, horizontal permeability is much
greater than vertical permeability, and air and moisture infiltration is generally slow. Soils
with prismatic or columnar structure have dominantly vertical permeability.. Platy and
prismatic structures form in soils with high clay contents. In soils with shrink-swell clays, air
.11-2 Reprinted from USGS'Open-tile Report 93-292
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Lead-214
27mln- XBlsmuth.214
138.4 days
Uranlum-238
.51 billion years
247i000 years
"J 80,000 years
Radlum-226 fa
1602 years
STABLE
Figure 1. The uraniurn-238 deeay series, showing the half-lives of elements and their modes of decay (after Wanty and
Schoen, 1991). a denotes alpha decay, p denotes beta decay.
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and moisture infiltration rates and depth of wetting may be limited when the cracks, in the
surface soil layers swell shut. Clay-rich B horizons, particularly those with massive or pl.aty
structure, can form a capping layer that impedes the escape of soil gas to the surface
(Schumann and others, 1992). However, the shrinkage of clays can act to open or widen
cracks upon drying, thus increasing the soij's permeability to gas flow during drier periods.
Radon transport in soils occurs by two processes: (1) diffusion and (2) flow (Tanner,
1964). Diffusion is the process whereby radon atoms move from areas of higher
concentration to areas of lower concentration in response to a concentration gradient. Flow is
the process by which soil air moves through soil pores in response to differences in pressure
within the soil or between the soil and the atmosphere, carrying the radon atoms along with it:
Diffusion is the dominant radon transport process in soils of low permeability, whereas flow
tends to dominate in highly permeable soils (Sextro and others, 198.7). 'In low-permeability
soils, much of the radon may decay before it is able to enter a building because its transport
rate is reduced. Conversely, highly permeable soils, even those that are relatively low in
radium, such as those derived from some types of glacial deposits, have been associated with
high indoor radon levels in Europe and in the northern United States (Akerblom and others,
1984; Kunz and others, 1989; Sextro and others, 1987). In areas of karst topography formed
in carbonate rock (limestone or dolomite) environments, solution cavities and fissures can
increase soil permeability at depth by providing additional pathways for gas flow.
Not all radium contained in soil grains and grain coatings will result in mobile radon
when the radium decays. Depending on where the, radium is distributed in the soil, many of
the radon atoms may remain imbedded in the soil grain containing the parent radium atom, or
become imbedded in adjacent soil grains. The portion of radium that releases radon into the
pores and fractures of rocks and soils is called the emanating fraction. When a radium atom
decays to radon, the energy generated is strong enough to send the radon atom a distance of
about 40 nanometers (1 nm = 10'* meters), or about 2x10:* inchesthis is known as alpha
recoil (Tanner, 1980). Moisture in the soil lessens the chance of a recoiling radon atom
becoming imbedded in an adjacent grain. Because water is more dense than air, a radon atom
will travel a shorter distance in a water-filled pore than in an air-filled pore, thus increasing
the likelihood that the radon atom will remain in the pore space. Intermediate moisture levels
enhance radon emanation but do not significantly affect permeability. However, high
moisture levels can significantly decrease the gas permeability of the soil and impede radon
movement through the soil.
Concentrations of radon in soils are generally many times higher than those inside of
buildings, ranging from tens of pCi/L to more than "100,000 pCi/L, but typically in the range
of hundreds to low thousands of pCi/L. Soil-gas radon concentrations can vary in response to
variations in climate and weather on hourly, daily, or seasonal time scales. Schumann and
others (1992) and Rose and others (1988) recorded order-of-magnitude variations in soil-gas
radon concentrations between seasons in Colorado and Pennsylvania. The most important
factors appear to be (1) soil moisture conditions, which are controlled in large part by
precipitation; (2) barometric pressure; and (3) temperature. Washington and Rose (1990)
suggest that temperature-controlled partitioning of radon between water and gas in soil pores
also has a significant influence on the amount of mobile radon in soil gas.
Homes in hilly limestone regions of the southern Appalachians were found to have higher
indoor radon concentrations during the summer than in the winter. A suggested cause for this
phenomenon involves temperature/pressure-driyen flow of radon-laden air from subsurface
II-4 Reprinted from USOS Open-File Report 93-292
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solution^ cavities in the carbonate rock into houses. As warm air enters solution cavities that
are higher on the hilislope than the homes,'it cools and 'settles, pushing radon-laden iair-from
lower in the cave or cavity system-in to structures on the hillslope (Gammage and others,
1993). In contrast, homes built over caves having openings situated .below the level of the
i.ome had higher indoor, radon levels in the winter, caused by cooler outside ai, entering the
cave, driving radon-laden air into cracks and solution cavities in the rock and soil, and
ultimately, into homes (Gammage and others, 1993). / "
RADON ENTRY INTO BUILDINGS
A driving force (reduced atmospheric pressure in the house relative to-the soil, .producing
a pressure gradient) and entry points must exist for radon to enter a building from the soil.
The negative pressure caused by furnace combustion, ventilation devices, and the stack effect
(the rising and escape of warm air from the upper floors of the building, causing a
temperature and pressure gradient within the structure) during cold winter months are
common driving forces. Cracks and other penetrations through building foundations, sump
holes, and slab-to-foundation wall joints are common entry points.
Radon levels in the basement are generally higher than those on the main floor or upper
floors of most structures. Homes with basements generally provide more entry points for
radon, commonly.have a more pronounced stack effect, and typically have' lower air pressure
relative to the surrounding soil than non-basement homes. The term "nonbas,ement" applies to
slab-on-^rade or crawl space construction. * , . '
METHODS AND SOURCES OF DATA
'The assessments'of-radon potential in the booklets that follow this introduction were
made using five main types of data: (1) geologic (lithologic); (2) aerial radjometric; (3) soil
characteristics, including soil moisture, permeability, and drainage characteristics; (4) indoor
radon data; and (5) building architecture .(specifically, whether homes in each area are built
slab-on-grade or have a basement or crawl space). These five factors were evaluated and
integrated to produce estimates of radon potential. Field measurements of soil-gas-radon or
soil radioactivity were not used except where such data were available in existing, published
reports of local" field studies". Where applicable, such field studies are described in the ,
individual state chapters. . . .
GEOLOGIC DATA " , '.-..; . .
The types and distribution of lithologic units and other geologic features in an
assessment area are of primary importance in determining radon potential. Rock types .that"
are most likely to cause indoor radon problems include carbonaceous black shales, glauconite-
bearing sandstones, certain kinds of fluvial sandstones and fluvial sediments, phosphorites,
chalk, karst-producing carbonate rocks, certain kinds of glacial deposits, bauxite, uranium-rich
granitic rocks, metamorphic rocks of granitic composition', silica-rich-volcanic rocks, many
sheared or faulted rocks, some coals, and certain kinds of contact metamorphosed rocks.
Rock types least likely to cause radon problems include marine quartz sands, non-
carbonaceous shales'and siltstones, certain kinds of clays, silica-poof metamorphic and
-"''.' ;' ' II-S ' . Reprinted from USGS Open-File Report 93-292
-------
igneous rocks, and basalts. Exceptions exist within these general lithologic groups because of
the occurrence of localized uranium deposits, commonly of the hydrothermal type in
crystalline rocks or the "roll-front" type in sedimentary rocks. Uranium arid radium are
commonly sited in heavy minerals, iron-oxide coatings on rock and soil grains, and organic
«,.aerials in soils and sediments. Less common are . ranium associated with pi: jsphate and
carbonate complexes in rocks and soils, and uranium minerals.
Although many cases of elevated indoor radon levels can be traced to high radium and
(or) uranium concentrations in parent rocks, some structural features, most notably faults and
shear zones, have been identified as sites of localized uranium concentrations (Deffeyes and
MacGregor, 1980) and have been associated with some of the highest reported indoor radon
levels (Gundersen, 1991). The two highest known indoor radon occurrences are associated
with sheared fault zones in Boyertown, Pennsylvania (Gundersen and others, 1988a; Smith
and others, 1987), and in Clinton, New Jersey (Henry and others, 1991; Muessig and Bell,
1988).
NURE AERIAL RADIOMETRIC DATA
Aerial radiometric data are used to quantify the radioactivity of rocks and soils.
Equivalent uranium (eU) data provide an estimate of the surficial concentrations of radon
parent materials (uranium, radium) in rocks and soils. Equivalent uranium is calculated from
the counts received by a gamma-ray detector from the 1.76 MeV (mega-electron volts).
emission energy corresponding to bismuth-214 ('"Bi), with the assumption that uranium and,
its decay products are in secular equilibrium. Equivalent uranium is expressed in units of
parts per million (ppm). Gamma radioactivity also may be expressed in terms of a radium
activity; 3 ppm eU corresponds to approximately 1 picocurie per gram (pCi/g) of radium-226.
Although radon is highly mobile in soil and its concentration is affected by meteorological
conditions (Kovach, 1945; Klusman and Jaacks, 1987; Schery and others, 1984; Schumann
and others, 1992), statistical correlations between average soil-gas radon concentrations and
average eU values for a wide variety of soils have been documented (Gundersen and others,
1988a, 1988b; Schumann and Owen, 1988). Aerial radiometric data can provide an estimate
of radon source strength over a region, but the amount of radon that is able to enter a home
from the soil is dependent on several local factors, including soil structure, grain size
distribution, moisture content, and permeability, as well as type of house construction and its
structural condition.
The aerial radiometric data used for these characterizations were collected as part of the
Department of Energy National Uranium Resource Evaluation (NURE) program of-the 1970s
and early 1980s. The purpose of the NURE program was to identify and describe areas in the
United States having potential uranium resources (U.S. Department of Energy, 1976). The
NURE aerial radiometric data were collected by aircraft in which a gamma-ray spectrometer
was mounted, flying approximately 122 m (400 ft) above the ground surface. The equivalent
uranium maps presented in the state chapters were generated from reprocessed NURE data in
which smoothing, filtering, recalibrating, and matching of adjacent quadrangle data sets were
performed to compensate for background, altitude, calibration, and other types of enws and
inconsistencies in the original data set (Duval .and others, 1989). The data were then gridded
and contoured to produce maps of eU with a pixel size corresponding to approximately 2.5 x
2.5 km (1.6 x 1.6 mi).
II-6 Reprinted from USGS Open-File Report 93.-192
-------
FLIGHT LINE SPACING OF XUKE AEK!AI SURVEYS
2 KU (I KILE)
5 IM (3 MILES)
2 * 5 III
E3 10 LU (6 U1LES)
Si: 10 EK
NO DiTA
Figure 2. Nominal flightline spacings for NURE aerial gamnia-ray surveys coveririg the
contiguous United States (fromDuval and others, 1990). Rectangles represent I°x2° quadrangles.
-------
Figure 2 is an index map of NURE 1° x 2° quadrangles showing the flight-line spacing
for each quadrangle. In general, the more closely spaced the flightlines are, the more area
was covered by the aerial gamma survey, and thus, more detail is available in the data set,
For an altitude of 400 ft above the ground surface and with primary flightline spacing
typically between 3 and 6 miles, less than 10 percent of the ground surface of the United
States was actually measured by the airborne gamma*ray detectors (Duval and others, 1989),
although some areas had better coverage than others due to the differences in flight-line
spacing between areas (fig. 2), This suggests that some localized uranium anomalies may not,
have been detected by the aerial surveys, but the good correlations of eU patterns with
geologic outcrop patterns indicate that, at relatively small scales (approximately 1:1,000,000
or smaller) the National eU map (Duval and others, 1989) gives reasonably'good estimates of
average surface uranium concentrations and thus can assist in the prediction of radon potential
of rocks and soils, especially when augmented with additional geologic and soil data.
The shallow (20-30 cm) depth of investigation of gamma-ray spectrometers, either
ground-based or airborne (Duval and others, 1971; Durrance, 1986), suggests that gamma-ray
data may sometimes underestimate the radon-source strength in soils in which some of the
radionuclides in the near-surface soil layers have been transported downward through the soil
profile. In such cases the concentration of radioactive minerals in the A horizon would be
lower than in the B horizon, where such miner.als are typically concentrated. The
concentration of radionuclides in the. C horizon and below may be relatively unaffected by
surface solution processes. Under these conditions the surface gamma-ray signal may indicate
a lower radon source concentration than actually exists in the deeper soil layers, which are
most likely to affect radon levels in structures with basements. The redistribution of
radionuclides in soil profiles is dependent on a combination of climatic, geologic, and
geochemical factors. There is reason to believe that correlations of eU with actual soil
radium and uranium concentrations at a depth relevant to radon entry into structures may be
regionally variable (Duval, 1989; Schumann and Gundersen, 1991). Given sufficient
understanding of the factors cited above, these regional differences may be~ predictable.
SOIL SURVEY DATA
Soil surveys prepared by the U.S. Soil Conservation Service (SCS) provide data on soil
characteristics, including soil-cover thickness, grain-size distribution; permeability, shrink-
swell potential, vegetative cover, generalized groundwater characteristics, and land use. The
reports are available in county formats and State summaries. Thfe county reports typically
contain both generalized and detailed maps of soils in the area.
Because of time and map-scale constraints, it was impractical to examine county soil
reports for each county in the United States, so more generalized summaries at appropriate
scales were used where available. For State or regional-scale radon characterizations, soil
maps were compared to geologic maps of the area, and the soil descriptions, shrink-swell
potential, drainage characteristics, depth to seasonal high water table, permeability, and other
relevant characteristics of each soil group noted. Technical soil terms used in soil surveys are
generally complex; however, a good summary of .soil engineering terms and the national
distribution of technical soil types is the "Soils" sheet of the National Atlas (U.S. Department
of Agriculture, 1987). .
II-8 Reprinted from USGS Open-File Report 9,3-292
-------
Soil permeability is commonly expressed in SCS soil surveys in terms of the speed, in
inches per hour (in/hr), at which water soaks into the soil, as measured in a soil percolation
test. Although in/hr are not truly units of permeability, these units are ir\ widespread use and
are referred/to as "permeability" in SCS soil surveys. The permeabilities listed in the SCS
surveys are for water, but they, generally correlate -\vell with gas permeability. Because data
on gas permeability of soils is extremely limited, data on permeability to water is used as a '
substitute except in cases in which excessive soil moisture is known to exist. Water in soil
pores inhibits gas transport, so the amount of radon available-to a home is effectively reduced
by a high water table. Areas likely to have high water tables include river valleys, coastal
areas, and some areas overlain by deposits of glacial origin (for example, loess).
Soil permeabilities greater than 6.0 in/hr may be considered high, and permeabilities less
than 0.6 in/hr may be considered low in terms of soil-gas transport. Soils with low
permeability may generally be considered to have a lower radon potential than more
permeable soils with similar radium concentrations. Many well-developed soils contain a
clay-rich B horizon that may impede vertical soil gas transport. Radon generated below this
horizon cannot readily escape to the surface, so it would instead tend to move laterally,
especially under the influence of a negative pressure exerted by a building. "*
Shrink-swell potential is an indicator of the abundance of smectitic (swelling) clays in a
soil. Soils with a high shrink-swell potential may cause building foundations to crack,
creating pathways for radon entry into the structure. During dry periods, desiccation cracks in
shrink-swell soils provide additional pathways for soil-gas transport and effectively* increase
the gas permeability of the soil. Soil permeability data and soil profile data thus provide "
important information for regional radon assessments.
INDOOR RADON DATA . . . ,; ' . - _, '
Two major sources of indoor radon data were used. The first and largesV source of data is
from the State/EPA Residential Radon Survey (Ronea-Battista and others, 1988; Dziuban and
others, 1990). Forty-two states completed EPA-sponsored indoor .radon surveys, between 1986
and 1992 (fig. 3). The State/EPA Residential Radon Surveys were designed to be
comprehensive and statistically significant at the state level, and were subjected to high levels
of quality assurance and control. The surveys collected screening indoor radon measurements,
defined as 2-7 day measurements using charcoal canister radon detectors placed in the lowest
livable area of the home. The target population for the surveys included owner-occupied
single family, defeched housing units (White and others, 1989), although attached structures
such as duplexes, townhouses, or condominiums were included in some of thS surveys if they
met the other criteria and had contact with the ground surface. Participants were selected
randomly from telephone-directory listings. In total, approximately 60,000 homes were tested
in the State/EPA surveys. "
The second source of indoor radon data comes from residential surveys that have been
conducted in a specific state or region of the country (e.g. independent state surveys or utility
company surveys). Several states, including Delaware, Florida^ Illinois, New Hampshire, New
Jersey, New York, Oregon, and Utah, have conducted their own "suryeys of indoor radon; The
quality and design of a state or other independent survey are discussed and referenced where
the data are used. . ,
II-9 Reprinted from USGS Open-File Report 93-292
-------
STATE/EPA RESIDENTIAL RADON
SURVEY SCREENING
0
Estimated Percent of Houses with Screening Levels Greater than 4 pCi/L
20 and >
The States of nR!-1.,NH,NJ,NY, and IJT
have conducted their own surveys. OK &
SO declincd'to participate in the SRKS.
These results arc based on 2-7 day screening
measurements in the lowest livable levei and should not
be used to estimate annual averages or health risks.
Figure 3. Percent of homes tested in the State/EPA Residential Radon Survey with screening indoor radon levels exceeding 4 pCi/L.
-------
Data for only those counties with five or more measurements are shown in the indoor -
radon maps in the state chapters, although data for all counties with a, nonzero number of
measurements are listed in the indoor radon data tables in each state chapter. In total, indoor
radon data from more than 100,000 homes nationwide were used in the compilation of these
assessments. Radon data from State or regional indoor radon surveys, public health
organizations, or other sources are discussed in addition to the primary data sources where
they are available. Nearly all of the data used in these evaluations represent short-term (2-7
day) screening measurements from the lowest livable space of the homes, Specific details
concerning the nature and use of indoor radon data sets other than the State/EPA Residential
Radon Survey are discussed in the individual State chapters.
RADON'INDEX AND CONFIDENCE INDEX . ,
Many of the geologic methods used ,to evaluate an area for radon, potential -require
subjective opinions based on the professional judgment and experience of the individual
geologist. The evaluations are nevertheless based on established scientific principles that are
universally applicable to any geographic area or geologic setting. This section describes,the
methods and conceptual framework used by the U.S. Geological Survey to evaluate areas for
radon potential based on the five factors discussed in the previous sections. The scheme is
divided into two basic parts, a Radon Index (RI), used to rank the general radon potential of
the area, and the Confidence Index (CI), used to express the level of confidence i»'the " . .
prediction based on the quantity and quality of the data used to make the determination. This
scheme works best if the areas to be evaluated are delineated by geologically-based
boundaries (geologic provinces) rather than political ones (state/county boundaries) in which
the geology may vary across the area.
Radon Index.' Table' 1 presents the Radon Index (RI) matrix. The five factorsindoor
radon data, geology, aerial radioactivity, soil parameters, and house foundation typewere
quantitatively ranked (using a point value of 1, 2, or 3) for their respective contribution to
radon potential in a given area. At least some data for the 5 factors are consistently available
for every geologic province. Because each of these main factors encompass a .wide variety of
complex and variable components, the geologists performing the evaluation relied heavily on
their professional judgment and experience in assigning point values to each category and in
determining the overall radon potential ranking. Background information on these factors is
discussed in more detail in the preceding sections of this introduction. .
Indoor radon was evaluated using unweighted arithmetic means of the indoor radon data
for each geologic area to be assessed. Other expressions of indoor-radon levels in an area
also could have been used, such as weighted averages or annual averages, but these types of
data were not consistently available for the entire United States at the time of this writing, oj
the schemes were not considered sufficient to provide a means of consistent comparison
across all areas. For this report, charcoal-canister screening measurement data from the
State/EPA Residential Radon Surveys and other carefully selected sources were used, as
described in the preceding section. To maintain consistency, other indoor radon data sets
(vendor, state, or other data) were not considered in scoring the indoor radon factor of the
Radon Index if they were riot randomly sampled or could not be statistically combined with
the primary indoor radon data sets. However, these additional radon data sets can provide a
means to further, refine correlations between geologic factors and radon potential* so they are
''., 11-11 Reprinted from USGS Open-File Report 93-292
-------
TABLE I. RADON INDEX MATRIX, "ppm elJ" indicates parts per million of equivalent
uranium, as indicated by MURE aerial radiometric data. See text discussion for details.
FACTOR
INDOOR RADON (average)
AERIAL RADIOACTIVITY
GEOLOGY*
SOIL PERMEABILITY
ARCHITECTURE TYPE
INCREASING RADON POTENTIAL ^
POINT VALUE
1
<2pCi/L
< 1.5 ppm eU
negative
low
mostly slab
2
2-4pCi/L
1.5 - 2.5 ppm eU
* variable
moderate
mixed
3
>4pCi/L
> 2.5 ppm eU
positive
high
mostly basement
*GEOLOGIC FIELD EVIDENCE (GFE) POINTS: GFE points are assigned in addition to points
for the "Geology" factor for specific, relevant geologic field stu'dies. See text for details.
Geologic evidence supporting: HIGH radon +2 points
MODERATE +1 point
LOW -2 points
No relevant geologic field studies 0 points .
SCORING:
Radon potential category
Point ranee
Probable average screening
indoor radon for area
LOW
MODERATE/VARIABLE
HIGH
3-8 points
9-11 points
12-17 points
< 2 pCi/L
2 - 4 pCi/L.
>4pCi/L
POSSIBLE RANGE OF POINTS = 3 to 17
TABLE 2. CONFIDENCE INDEX MATRIX
INCREASING CONFIDENCE
FACTOR
INDOOR RADON DATA
AERIAL RADIOACTIVITY
GEOLOGIC DATA
SOIL PERMEABILITY
POINT VALUE
1
sparse/no data
questionable/no data
questionable
questionable/no data
2
fair coverage/quality
glacial cover
variable
variable
3 ' ,
good coverage/quality
no glacial cover
proven geol. model
reliable, abundant
SCORING:
LOW CONFIDENCE
MODERATE CONFIDENCE
HIGH CONFIDENCE
4-6 points
7-9 points
10 -12 points
POSSIBLE RANGE OF POINTS = 4 to 12
BE-12 Reprinted torn USGS Open-File Report 93-292
-------
included as supplementary information and are discussed in the individual State chapters. If
the average screening indoor radon level for an area was less than 2 pCi/L, the indoor radon
factor was assigned 1 point, if it was between 2 and 4 pCi/L,,it was scored 2 points, and if
the average screening indoor radon level for an area was greater than 4 pCi/L, the indoor,
radon factor was assigned 3 RI points. -...'
, Aerial radioactivity data used in this report are from the equivalent uranium map of the
conterminous United States compiled from NURE aerial gamma-ray surveys (Duval and
others, 1989). These data indicate the gamma radioactivity from approximately the upper 30
cm of rock and soil, expressed in units of ppm equivalent uranium. 'An, approximate average
value of eU was determined visually for each area and point values assigned based on
whether the overall eU for the area falls below 1.5 ppm (1 point), between 1.5 .and 2.5 ppm
(2 points), or greater than 2.5 ppm (3' points).
The geology factor is complex and actually incorporates many geologic characteristics. In
the matrix, "positive" and "negative" refer to the presence or absence and distribution of rock
types known to have high uranium contents and to generate elevated radon in soils, or indoors.
Examples of "positive" rock types include granites, black shales, phosphatic rocks, and other
rock types described in the preceding "geologic data" section. Examples-^ "negative" rock
types include marine quartz sands and some clays. The term "variable" indicates that the
geology within the region is variable or that the rock types in the area are known or suspected
to generate elevated radon in some areas but not in others due to compositional differences,
climatic effects, localizeddistribution of uranium, or other factors. Geologic information
indicates not only how much uranium is present in the rocks and soils but also gives clues for
predicting general radon emanation and mobility characteristics through additional factors
such as structure (notably the presence of faults or shears) and geochemica3! Characteristics
(for example, a phosphate-rich sandstone will likely contain more uranium than a"sandstone
containing little or no phosphate because the phosphate forms chemical complexes with
uranium), "Negative", "variable", and "positive" geology were assigned 1, 2, and 3 points,
respectively. "' .'' ' - . .
In cases where additional reinforcing or contradictory geologic evidence is available,
Geologic Field Evidence (GFE) points were added to or subtracted from an area's score
(Table 1). Relevant geologic field studies are important tp enhancing our understanding of
how geologic processes affect radon distribution. In some cases, geologic models and
supporting field data reinforced an already strong (high or-low) score; in others, they provided
important contradictory data. GFE points were applied for geologically-sound evidence that
supports the prediction .(but which may contradict one or more factors) on the basis of known
geologic field studies in the area or in areas with geologic and climatic settings similar .
enough that they could be applied with full confidence. For example, 'areas of the Dakotas,
Minnesota, and Iowa that are covered with Wisconsia-age glacial deposits exhibit a low aerial
radiometric signature and score only one RI point in that category. However, data from
geologic field studies in North Dakota and Minnesota (Schumann and others, 1991) suggest
that eU is a poor predictor of; geologic radon potential in this area because radionuclides have
.. ' ' / * - -...-' -11-13 Reprinted from USGS Open-File Report 93-292,
-------
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
categorieslow, 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
factorsif two of the five factors are allowed to vary from the "ideal" for a category, they
can differ by a minimum of 2 (1 point different each) and a maximum of 4.points (2 points
different each). With "ideal" scores of 5, 10, and 15 points describing low, moderate, and
high geologic radon potential, respectively, an ideal low score of 5 points plus 3 points for
possible variability allows a maximum of 8 points in the low category. Similarly, an ideal ,
high score of 15 points minus 3 points gives a minimum of 12 points for the high category.
Note, however, that if both other factors differ by two points from the "ideal", indicating
considerable variability in the system, the total point score would lie in the adjacent (i.e.,
moderate/variable) category.
Confidence Index. Except for architecture type, the same factors were used to establish a
Confidence Index (CI) for the radon potential prediction for each area (Table 2). Architecture
type was not included in the confidence index because house construction data are readily and
reliably available through surveys taken by agencies and industry groups including the
National Association of Home Builders, U.S. Department of Housing and Urban
Development, and the Federal Housing Administration; thus it was not considered necessary
11-14 Reprinted from USGS Open-File Report 93-292
-------
to question the quality of validity of these data. The other factors were scored on the basis of
the quality and quantity of the data used to complete the RI matrix,
Indoor radon data were evaluated based on the distribution and number of data points and
on whether the data were collected by random sampling (State/EPA Residential Radon Survey
or other state survey data) or volunteered vendor daia (likely to be nonrandom.and biased
toward population centers arid/or high indoor radon levels). The. categories listed in the CI
matrix for indoor radon data ("sparse or no data", "fair coverage or quality", and "good
coverage/quality") indicate the sampling density and statistical robustness of an indoor radon
data set. Data from the State/EPA Residential Radon Survey and statistically valid state
surveys were typically assigned 3 Confidence Index points unless the data were poorly
distributed or absent in the area evaluated.
Aerial radioactivity data are available for all but a few areas of the continental United
States and for part of Alaska. An evaluation of the quality of the radioactivity data was based
on whether there appeared to be a good correlation between the radioactivity and the actual
amount of uranium or radium available to generate mobile radon in the rocks and soils of the
area evaluated. In general,'the greatest problems with correlations among eU, geology, and
soil-gas or indoor radon levels were associated with glacial deposits (see the discussion in a
previous section) and typically were assigned a 2-p'oint Confidence Index score. Correlations
among eU, geology, and radon were generally sound in unglaciated areas and were usually
assigned 3 CI points. Again, however, radioactivity data in some unglaciated areas may have
been assigned fewer than 3 points, and in glaciated areas may be assigned only one point,, if
the data were.considered questionable or if coverage was poor.
To assign Confidence Index scores for the geologic data factor, rock types and geologic
settings for which a physical-chemical, process-based understanding of radon generation and
mobility exists were regarded as having "proven geologic models" (3 points); a high
confidence could be held for predictions in such areas. Rocks for which the processes are
less well known or for which data are contradictory were regarded as "variable" (2 points),
and those about which little is known or for which no apparent correlations have been found
were deemed "questionable" (1 point). '
The soil permeability factor was also scored based on quality and amount of data. The
three categories fpr soil permeability in the Confidence Index are similar in concept, and
scored similarly, to those for the geologic data factor. Soil permeability can be roughly
estimated from grain size and drainage class if data from standard, accepted soil percolation
tests are unavailable; however,- the reliability of the data would be lower than if percolation
test figures or other measured permeability data are available, because ah estimate of this type
does not encompass all the factors that affect soil permeability and thus may be inaccurate in
some instances. Most published soil permeability data are for water; although this is
generally elosely related to the air permeability of the soil, there are some instances when it
may provide an incorrect estimate. Examples of areas in which water permeability data may
npt accurately reflect air permeability include areas with consistently high levels of soil
moisture, or clay-rich soils, which would have a low water permeability but may have a
, ' 11-15 Reprinted from USGS Open-File Report 93-292
-------
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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daughters: Radiation Protection Dosimetry, v 7, p. 49^54.
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Durrance, E.M., 1986, Radioactivity in geology: Principles and applications: New York, N.Y.,
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Duval, J.-S., 1989, Radioactivity and some of its applications in geology: Proceedings of the
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Duval, J.S., Cook, E.G., and Adams, J.A.S., 1971, Circle of investigation of an airborne
gamma-ray spectrometer: Journal of Geophysical Research, v. 76, p. 8466-8470.
> - ' " ., .'-"''' ,''
' ''..'. < , -
Duval, J.S., Jones, W.J., Riggle, F.R., and Pitkin, J.A., 1989, Equivalentinanium map of
conterminous,United States: U.S. Geological Survey Open-File Report 89-478,10 p.
Duval, J.S., Reimer, G.M., Schumann, R.R., Owen,,D,E., and Otton, J.K., 1990, Soil-gas
radon compared to aerial and ground gamma-ray measurements at study sites near Greeley
and Fort Collins, Colorado: U.S. Geological Survey Open-File Report 90-648,42 p.
Dziuban, J.A., Clifford, M.A., White, S.B., Bergstein, J.W., and Alexander, B.V., 1990,
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Environmental Protection Agency report EPA/600/9-90/005C, Paper IV-2," 17 p.
Gammage, R.B., Wilson, D.L., Saultz, R.J., and Bauer, B.C., 1993, Subterranean transport of/
radon and elevated indoor radon in hilly karst terranes: Atmospheric Environment
(in press).
Gundersen, L.C.S., Reimer, G.M., and Agard, S.S., I988a, Correlation between geology, radon
in soil gas,,and indoor radon in the Reading Prong, in Marikos, M.A., and Hansman, .
R.BL, eds., Geologic causes of natural radionuclide anomalies: Missouri Department of
Natural Resources Special Publication 4, p. 91-102.
Gundersen, L.C.S, Reimer, G.M., Wiggs, C.R., and Rice, C.A., 1988b, Map showing radon
potential of rocks and soils in Montgomery County, Maryland: U.S. Geological Survey
Miscellaneous Field Studies Map MF-2043, scale 1:62,500.
Gundersen, Linda C.S., 1991, Radon in sheared metamorphic and igneous rocks, in Gundersen,
Linda C.S., and Richard B. Wanty, eds., Field studies of radon in rocks, soils, and water:
. U.S. Geol.-Survey Bulletin no. 1971, p. 39-50. '
II-I7 Reprinted from USGS Ppen-File Report 93-292
-------
Henry, Mitchell E., Kaeding, Margret E., and Monteverde, Donald, 1991, Radon in soil gas and
gamma-ray activity of rocks and soils at the Mulligan Quarry, Clinton, New Jersey, in
Gundersen, Linda C.S., and Richard B. Wanty, eds., Field studies of radon in rocks,
soils, and water: U.S. Geol. Survey Bulletin no. 1971, p. 65-75.
Klusman, R. W., and Jaacks, J. A., 1987, Environmental influences upon mercury, radon, and
helium concentrations in soil gases at a site near Denver, Colorado: Journal of
Geochemical Exploration, v. 27, p. 259-280.
Kovach, E.M., 1945, Meteorological influences upon the radon content of soil gas: Transactions,
American Geophysical Union, v. 26, p. 241-248.
Kunz, C, Laymon, C.A., and Parker, C., 1989, Gravelly soils and indoor radon, in Osborne,
M.C., and Harrison, J., eds., Proceedings of the 1988 EPA Symposium on Radon and
Radon Reduction Technology, Volume 1: U.S. Environmental Protection Agency Report
EPA/6QO/9-89/006A, p. 5-75-5-86.
Muessig, K., and Bell, C., 1988, Use of airborne radiometric data to direct testing for elevated
indoor radon: Northeastern Environmental Science, v. 7, no. 1, p. 45-51.
Ronca-Battista, M., Moon, M., Bergsten, J., White, S.B., Holt, N.t and Alexander, B., 1988,
, Radon-222 concentrations in the United StatesResults of sample surveys in five states:
Radiation Protection Dosimetry, v. 24, p. 307-312.
Rose, A.W., Washington, J.W., and Greeman, D.J., 1988, Variability of radon with depth and .
season in a central Pennsylvania soil developed on limestone: Northeastern Environmental
Science, v. 7, p. 35-39.
Schery, S.D., Gaeddert, D.H., and Wilkening, M.H., 1984, Factors affecting exhalation of radon
from a gravelly sandy loam: Journal of Geophysical Research, v. 89, p. 7299-7309.
Schumann, R.R., and Owen, D.E., 1988, Relationships between geology, equivalent uranium
concentration, and radon in soil gas, Fairfax County, Virginia: U.S. Geological Survey
Open-File Report 88-18,28 p.
Schumann, R.R., and Gundersen, L.C.S., 1991, Regional differences in radon emanation ~
coefficients in soils: Geological Society of America Abstracts With Programs, V. 23,
no. 1, p. 125. .
Schumann, R.R., Peake, R.T., Schmidt, K.M., and Owen, D.E., 1991, Correlations of soil-gas
and indoor radon with geology in glacially derived soils of the northern Great Plains, in
Proceedings of the 1990 International Symposium on Radon and Radon Reduction
Technology, Volume 2, Symposium Oral Papers: U.S. Environmental Protection Agency
report EPA/600/9-9 l/026b, p. 6-23-6-36.
IJ-18 Reprinted from USGS Open-File Report 93-292
-------
Schumann, R.R., Owen, D.E., and Asher-Bdlinder, S., 1992, Effects of weather and soil
characteristics on temporal variations in soil-gas radon concentrations, in Gates, A.E., and
Gundersen, L.C.S., eds., Geologic controls on radon: Geological Society of America
Special Paper 271, p, 65-72.
Sextro, R.G., Moed, B.A., Nazaroff, W.W., Revzan, K.L., and Nero, A.V., 1987,
Investigations of soil as a source of indoor radon, in Hopke, P.K., ed., Radon and its
decay products: American Chemical Society Symposium Series 331, p. 10-29.
Sterling, R., Meixel, G., Shen, L., Labs, K., and Bligh, T., 1985, Assessment of the energy
savings potential of building foundations research: Oak Ridge, Tenn., U.S. Department of
Energy Report ORNL/SUB/84-0024/1.
Smith, R.C,, II; Reilly, M.A., Rose,: A,W., Barnes, J.H., and Berkheiser, S.W., Jr., 1987,
Radon: a profound case: Pennsylvania Geology, v. 18, p. 1-7.
Tanner, A.B., 1964, Radon migration in the ground: a review,in Adams, J.A.S., and Lpwder,
W.M., eds., The natural radiation environment: Chicago, 11., University of Chicago
Press, p. 161-190. ' '
Tanner, A.B., 1980, Radon migration in the ground: a supplementary review, in GeseE, T.F.,-
, and Lowder, W.M. (eds), Natural radiation environment ffl, Symposium proceedings,
Houston, Texas, v. 1, p. 5-56.
U.S. Department of Agriculture, 1987, Principal kinds of soils: Orders, suborders, and great
groups: UJS. Geological Survey, National Atlas of the United States of America, sheet
38077-BE-NA-07M-00, scale 1:7,500,000. l . '
U.S. Department of Energy, 1976, National Uranium Resource Evaluation preliminary report,
prepared by the U.S. Energy Research and Development Administration, Grand Junction,
, Colo.: GJO-11(76).
Wanty, Richard B., and Schoen, Robert, 1991, A review of the chemical processes affecting the
mobility of radionuclides in natural waters, with applications, in Gundersen, Linda C.S.,
and Richard B. Wanty, eds., Field studies of radon in rocks, soils, and water: U.S.
. Geological Suryey Bulletin no. 1971, p. 183-194. , ,,
Washington, J.W., and Rose, A.W., 1990, Regional and temporal relations of radon in soil gas to
soil temperature and moisture: Geophysical Research Letters, v. 17, p. 829-832.
White, S.B., Bergsten, J.W., Alexander, B.V., and Ronca-Battista, M., 1989, Multi-State
.surveys of indoor 222Rn: Health Physics* v. 57, p. 891-896.
II-19 Reprinted from USGS Open:Fite Report 93-292
-------
APPENDIX A
GEOLOGIC TIME SCALE
Subdivisions {and their symbols)
Eon or
Eonothtm
Phantrczoic2
Prottrozoie
ipi
Arches n
f&i
Era or
Erathem
Cenozoic J
(CD
Mesozoic2
(Md
Ja!eo20!c
(Pi)
. U". H*
PlOt*IGl&C i2\
M«jo.i
Pnwaiaie fYl
lirty
Presets* tXi
L«f
Arefw«« CWJ
WicdH
A/eh*»n IV)
£»"₯
ArenȤn
Permian
. JPJ
Pennsylvanian
Csrboniferous
-------
APPENDIX B
GLOSSARY OF TERMS
Units of measure
pCi/L (picocuries per liter)- a unit of measure of radioactivity used to describe radon
concentrations in a volume of air. One pieoeurie (10~12 curies) is equal to about 2,2 disintegrations
of radon atoms per minute. A liter is about 1.06 quarts. The average concentration of radon in
U.S. homes measured to date is between 1 and 2 pCi/L. .
Bq/m3 (Becquerels per cubic meter)- a metric unit of radioactivity used to describe radon ,
concentrations in a volume of air. One becquerel is equal to one radioactive disintegration per
second. One"pCi/L is equal to 37 Bq/m3.
ppm (parts per million)- a unit of measure of concentration by weight of an element in. a
substance, in this case, soil or rock. One ppm of uranium contained in a ton of rock corresponds
to about 0.03 ounces of uranium. The average concentration of uraniufn,in soils in the United
States is between 1 and 2 ppm. "
in/hr (inches per hour)- a unit of measure used by soil scientists and engineers to describe the
permeability of a soil to water flowing through it, It is measured by digging a*hole 1 foot (12
inches) square and one foot deep, filling it with water, and measuring the time it takes for the water
to drain from the hole. The drop in height of the water level in the hole, measured in inches, is
then divided by the time (in hours) to determine the permeability. Soils range in permeability from
less than 0.06 in/hr to greater than 20 in/hr, but most soils in .the United States have permeabilities
between these two extremes. '.'.-. -
Geologic terms and terms related to the study of radon Vi , ,
aerial radiometric, aeroradiometrie survey A survey of radioactivity, usually gamma rays,
taken by an aircraft carrying a gamma-rayspectrometer pointed at the ground surface.
» * - " - = v.*1
alluvial fan A low, widespread mass of loose rock and soil material, shaped like an open fan
and deposited by a stream at the point where it flows from a narrow mountain valley out onto a
plain or broader valley. May also form at the junction with larger streams or when the gradient of
the stream abruptly decreases. " .
I ;V '',-. - . . ' ' . .
alluvium, alluvial General terms referring to unconsolidated detrital material deposited by a
stream or other body pf running water.
alpha-track detector A passive radon measurement device consisting of a plastic film that is
sensitive to alpha particles. The film is etched with acid in a laboratory after it is exposed. The
etching reveals scratches, .or "tracks", left by the alpha particles resulting from radon decay, which
can then be counted to calculate the radon concentration. Useful for long-term (1-12 months)
radon tests. . S!
amphibolite A mafic metamorphic rock consisting maMy of pyroxenes and(or) amphibole and
plagioclase. , ^
11-21 Reprinted from USGS Open-File Report 93-292
-------
argillite, argillaceous Terms referring to a rock derived from clay or shale, or any sedimentary
rock containing an appreciable amount of clay-size material, i.e., argillaceous sandstone,
arid Term describing a climate characterized by dryness. or an evaporation rate that exceeds the
amount of precipitation.
basalt A general term for a dark-colored mafic igneous rocks that may be of extrusive origin,
such as volcanic basalt flows, or intrusive origin, such as basalt dikes.
batholith A mass of plutonic igneous rock that has more than 40 square miles of surface
exposure and no known bottom.
carbonate A sedimentary rock consisting of the carbonate (COa) compounds of calcium,
magnesium, or iron, e.g. limestone and dolomite.
carbonaceous Said of a rock or sediment that is rich in carbon, is coaly, or contains organic
matter.
charcoal canister A passive radon measurement device consisting of a small container of
granulated activated charcoal that is designed to adsorb radon. Useful for short duration (2-7 days)
measurements only. May be referred to as a "screening" test
chert A hard, extremely dense sedimentary rock consisting dominantly of interlocking crystals of
quartz. Crystals are not visible to the naked eye, giving the rock a milky, dull luster. It maybe
white or gray but is commonly colored red, black, yellow, blue, pink, brown, or green.
clastic pertaining to a rock or sediment composed of fragments that are derived from preexisting
rocks or minerals. The most common clastic sedimentary rocks are sandstone and shale.
clay A rock containing clay mineral fragments or material of any composition having a diameter
less than 1/256 mm.
clay mineral One of a complex and loosely defined group of finely crystalline minerals made up
of water, silicate and aluminum (and a wide variety of other elements). They are formed chiefly by
alteration or weathering of primary silicate minerals. Certain clay minerals are noted for their small
size and ability to absorb substantial amounts of water, causing them to swell. The change in size
that occurs as these clays change between dry and wet is referred to as their "shrink-swell"
potential.
concretion A hard, compact mass of mineral matter, normally subspherical but commonly
irregular in shape; formed by precipitation from a water solution about a nucleus or center, such as
a leaf, shell, bone, or fossil, within a sedimentary or fractured rock.
conglomerate A coarse-grained, clastic sedimentary rock composed of rock and mineral
fragments larger than 2 mm, set in a finer-grained matrix of clastic material.
cuesta A hill or ridge with a gentle slope on one side and a steep slope on the other. The
formation of a cuesta is controlled by the different weathering properties and the structural dip of
the rocks forming the hill or ridge.
daughter product A nuclide formed by the disintegration of a radioactive precursor or "parent"
atom.
11-22 Reprinted from USGS Open-File Report 93-292
-------
delta, deltaic Referring to a low, flat, alluvial tract of land having a triangular or fan shape,
located at or near the mouth of a river. It results from the accumulation of sediment deposited by a
river at the point at which the river loses its ability to transport the sediment, commonly where a
river meets a larger body of water such as a lake or ocean, .
dike A tabular igneous intrusion of rock, younger than the surrounding rock, that commonly cuts
across the bedding or foliation of the rock it intrudes, .
dibrite A plutonic igneous rock that is medium in.color and contains visible dark minerals that
make up less than 50% of the rock. It also contains abundant sodium plagioclase and minor -
quarto , . .
dolomite A carbonate sedimentary rock of which more than 50% consists of the mineral dolomite
(CaMg(CO3)2), and is commonly white, gray, brown, yellow, of pinkish in color,
drainage The manner in which the waters of an .area pass, flow off of,, or flow into the soil.
Also refers to the water features of an area, such as lakes and rivers, that drain it.
eolian Pertaining to sediments deposited by the wind. .
esker A long, narrow, steep-sided ridge composed of irregular beds of sand and gravel deposited
by streams beneath a glacier and left behind when the ice melted.
evapotranspiration Loss of water from a land area by evaporation from the; soil and.
.transpiration from plants,
extrusive Said of igneous rocks that have been erupted onto the surface of the Earth.
fault, A fracture or zone of fractures in rock or sediment along which .there has been movement
fluvial, fluvial deposit Pertaining to sediment that has been deposited by a river or stream.
foliation A linear feature in a rock defined by both mineralogic and structural characteristics. It
may be formed during deformation or metamorphism. ..-,.
formation A mappable body of rock having similar characteristics. -
glacial deposit Arty sediment transported and deposited by a glacier or processes associated
with glaciers, such as glaciofluvial sediments deposited by streams flowing from melting glaciers.
gneiss A rock formed by metamorphism in which bands and lenses of minerals of similar
composition alternate with bands and lenses of different composition, giving the rock a striped or
"foliated" appearance.
granite Broadly applied, any coarsely crystalline, quartz- and feldspar-bearing igneous plutonic
rock. Technically, granites have between 10 and 50% quartz, and alkali feldspar comprises at least
65% of the total feldspar.
gravel An unconsolidated, natural accumulation of rock fragments consistmg, predominantly of
particles greater than 2 mm in size. . . . .
heavy minerals Mineral grains in sediment or sedimentary rock having higher than average
specific gravity. May form layers and lenses because of wind or water sorting by weight and size
11-23 Reprinted from USGS Open-File Report 93-292
-------
and may be referred to as a "placer deposit." Some heavy minerals are magnetite, garnet, zircon,
monazite, and xenotime.
igneous Said of a rock or mineral that solidified from molten or partly molten rock material. It is
one of the three main classes inio which row~> are divk _,
-------
; physiographic province A region in which all parts are similar in geologic structure and
climate, which has had a uniform geomorphic history, and whose topography or landforms differ
significantly from adjacent regions.
placer deposit See heavy minerals l
residual Formed by weathering of a material in place,
residuum Deposit of residual material.
rhyolite An extrusive igneous rock of volcanic origin, compositionally equivalent to granite.
sandstone A clastic sedimentary rock composed of sand-sized rock and mineral material that is
more of less firmly cemented. Sand particles range from 1/16 to 2 mm in size.
schist A strongly foliated crystalline rock, formed by metamorphism, that can be readily split intd
thin flakes or slabs. Contains mica; minerals are typically aligned.
screening level Result of an indoor radon test taken with a charcoal canister or similar device,
for a short period of time, usually less than seven days. May indicate the potential for an indoor.
radon problem but does, not indicate annual exposure to radon,
sediment Deposits of rock and mineral particles or fragments originating from material that is
transported .by air, water or ice, or that accumulate by natural chemical precipitation or secretion of
organisms. '..._''.
semiarid Refers to a climate that has slightly more precipitation than an arid climate. .
shale A fine-grained sedimentary rock formed from solidification (lithification) of clay or mud.
shear zone Refers to a roughly linear zone of rock that has been faulted by dmtile or non-ductile
processes in Which the rock is sheared and both sides are displaced relative to one another.
shrink-swell clay. See clay mineral.
siltstone A fine-grained clastic sedimentary rock composed of silt-sized rock and mineral
material and more or less firmly cemented. Silt particles range from 1/16 to 1/256 mm in size.
-sinkhole A roughly circular depression in a karst area measuring meters to tens of meters in
diameter. It is funnel shaped and is formed by collapse of the surface material into an underlying .
void created by the dissolution of carbonate rock. ,.,'-.
slope An inclined part of the earth's surface. *
solution cavity A hole, channel or. cave.-like cavity formed by dissolution of rock.
- stratigraphy The study Of rock strata; also refers to the succession of rocks of a particular area.
surficial materials Unconsolidated glacial, wind-, or waterborne deposits occurring uu the
earth's surface.
tablelands General term for a broad, elevated region with a nearly level surface of considerable
extent. . , '. ' - .
TL-25 Reprinted from USGS;Open-FileReport 93-292
-------
terrace gravel Gravel-sized material that caps ridges and terraces, left behind by a stream as it
cuts down to a lower level.
terrain A tract or region of the Earth's surface considered as a physical feature or aft ecological
environment
till Unsorted, generally unconsolidated and unbedded rock and mineral material deposited directly
adjacent to and underneath a glacier, without reworking by meltwater. Size of grains varies greatly
from clay to boulders.
uraniferous Containing uranium, usually more than 2 ppm.
vendor data Used in this report to refer to indoor radon data collected and measured by
commercial vendors of radon measurement devices and/or services.
volcanic Pertaining to the activities, structures, and extrusive rock types of a volcano.
water table The surface forming the boundary between the zone of saturation and the zone of
aeration; the top surface of a body of unconfined groundwater in rock or soil.
weathering The destructive process by which earth and rock materials, on exposure to
atmospheric elements, are changed in color, texture, composition, firmness, or form with little or
no transport of the material.
n-26 Reprinted from USGS Open-FEe Report 93-292
-------
APPENDIX C
EPA REGIONAL OFFICES
EPA Regional Offices
State
EPA Region
EPA Region 1
JFK Federal Building
Boston, MA 02203 ,
(617) 565-4502
EPA Region 2
(2A1R;RAD)
26 Federal Plaza
New York,'NY 10278
(212)264-4110
Region 3 (3AH14)
841 Chestnut Street
Philadelphia, PA 19107
(215) 597-8326
EPA Region 4
345 Courtland Street, N.E.
Atlanta, GA 30365
(404) 347-3907
EPA Region 5 (5AR26)
77 West Jackson Blvd.
Chicago, IL 60604-3507
(312) 886-6175
EPA Region 6 (CT-AS)
1445 Ross Avenue
Dallas, TX 75202-2733
(214) 655-7224
EPA Region 7
726 Minnesota Avenue
Kansas City, KS 66101
(913) 551-7604
EPA Region 8
(8HWM-RP)
999 18th Street
One Denver Place, Suite 1300
Denver, CO 80202-2413
(303) 293-1713
* *
EPA Region 9 (A-3J
75 Hawthorne Street
San Francisco, CA 94105
(415) 744-1048
f
EPA Region 10
1200 Sixth Avenue
Seattle, WA 98101
(202) 442-7660
Alabama 4
Alaska ,-.., ',.,.. 10
Arizona ,, 9
Arkansas ..,,. ,.,,....,6
California 9
Colorado.....,.;....... 8
Connecticut ; 1
Delaware......... .....3
District of Columbia 3
Florida 4
Georgia 4
Hawaii 9
Idaho 10
Illinois.. ; ...,5
Indiana .» ^ ...5
Iowa .,...» i.."...... :7
Kansas .'........-. , 7
Kentucky .....4
Louisiana ..A *....6
Maine .- 1
Maryland ,. , 3
Massachusetts 1
Michigan ..' ,5
Minnesota..... .,",,:,....5
Mississippi ,',,.4
Missouri , 7-
Montana 8
Nebraska, ......." .....7
Nevada.... 9.
New Hampshire 1
New Jersey »: 2
New Mexico..,., ;,6
New York 2
North Carolina ....4
North Dakota 8
Ohio ....:...'. 5
Oklahoma 6
Oregon 10
Pennsylvania.,.. '.3
Rhode Island . 1
South Carolina..; , ...4 .
South Dakota... .......8
Tennessee 4
Texas , 6
Utah.... .....8
Vermont..... '....,...1
Vkginia ...3
Washington 10
West Vkginia '. ....".,..3
Wisconsin ... .....5
Wyoming 8
H-27 Reprinted from USGS Open-File Report 93-292
-------
STATE RADON CONTACTS
May, 1993
Alabama James McNees
Division of Radiation Control
Alabama Department of Public Health
State Office Building
Montgomery, AL 36130
(205)242-5315
1-800-582-1866 in state
Afasfa Charles Tedfoid
Department of Health and Social
Services
P.O. Box 110613
Juneau.AK 99811-0613
(907)465-30*19
1-800-478-4845 in state
Arizona John Stewart
Arizona Radiation Regulatory Agency
4814 South 40th St.
Phoenix, AZ 85040
(602) 255-4845
Arkansas LeeGershner
Division of Radiation Control-
Department of Health
4815 Markham Street, Slot 30
Little Rock, AR 72205-3867
(501) 661-2301
California J. David Quinton
Department of Health Services
714 P Street, Room 600
Sacramento, CA 94234-7320
(916) 324-2208
1-800-745-7236 in state
Colorado LindaMartin
Department of Health
4210 East llth Avenue
Denver, CO 80220
(303)692-3057
1-800-846-3986 in state
Connecticut Alan J. Siniscalchi
Radon Program
Connecticut Department of Health
Services
150 Washington Street
Hartford, CT 061064474
(203) 566-3122
Delaware MaraiG.Rejai
Office of Radiation Control
Division of Public Health
P.O. Box 637
Dover," DB 19903
(302) 736-3028
1-800-554-4636 In State
District Robert Davis
of Columbia DC Department of Consumer and
Regulatory Affairs
614 H Street NW
Room 1014
Washington, DC 20001
(202)727-71068
Florida N. Michael Gilley
Office of Radiation Control
Department of Health and
RehabffitativeServices
1317 Winewood Boulevard
Tallahassee, Ft 32399-0700
(904)488-1525
1-800-543-8279 in state
Richard Schreiber
Georgia Department of Human
Resources
878 Peachtree St, Room 100
Atlanta, GA 30309
(404) 894-6644
1-800-745-0037 in state
Hawaii Russell Takata
Environmental Health Services
Division
591 Ala Moana Boulevard
Honolulu, ffl 96813-2498
(808) 586-4700
H-28
Reprinted from USGS Open-File Report 93-292
-------
Idaho
Iowa
Kansas
Kentucky
PatMcGavarn
Office of Environmental Health
450 West'State Street
Boise, ID 83720
(208)334-6584
1-80Q-W5-8647 in state
Richard Allen '
Illinois Department of Nuclear Safety
1301 Outer Park Drive
Springfield, IL 62704
(217)524-5614
1-800-325-1245 in state
Lorand Magyar
Radiological Health Section
Indiana State Department of Health
1330 West Michigan Street
P.O. Box 1964
Indianapolis, IN 46206
(317)633-8563
1-800-272-9723 In State
Donald A. Hater
Bureau of Radiological Health
Iowa Department of Public Health
Lucas State Office Building
Des Moines, IA 50319-0075"
(515) 281-3478
1-800-383-5992 In State '
Harold Spiker
Radiation Control Program
Kansas Department of Health and
Environment , -
109 SW 9th Street
6th Floor Mills Building
Topeka, KS 66612 .
(913)296-1561
JeanaPheJps
Radiatipn Control Branch
Department of Health Services
Cabinet for Human Resources
275 East Main Street
Frankfort, KY 40601
(502)564-3700
Louisiana Matt Schlenker
Louisiana Department of
Environmental Quality
P.O. Box 82135
Baton Rouge, LA 70884-2135
(504)925-7042
1-800-256-2494 in state
Maine BobStilwell i
Division of Health Engineering
Department of Human Services
, State House, Station 10
Augusta, ME 04333
(207)289-5676
1-800-232-0842 in state
Maryland Leon J. Raehuba
Radiological Health Program
Maryland Department of the
; Environment
2500 Broening Highway
Baltimore, MD 21224
(410)631-3303*
: 1-800-872-3666 MState
Massachusetts William J. Bell
Radiation Control Program
Department of Public Health
23 Service Center
Northampton, MA 01060
(413)586-7525
1-800-445-1255 in state
'' ':<»
Michigan SueHendeishott
Division of Radiological Health
Bureau of Environmental and
. Occupational Health
3423 North Logan Street
P.O. Box 30195
Lansing, MI 48909
(517)335-8194 .
Minnesota LauraQatmann
Indoor Air Quality Unit
925 Delaware'Street, SB
P.O. Box 59040
Minneapolis, MN 55459-0040
(612) 627-5480
1-800-798-9050 in state
11-29 Reprinted from USGS Open-File Report 93-292
-------
Mississippi
Missouri
Montana
Silas Anderson
Division of Radiological Health
Department of Health
3 150 Lawson Street
P.O. Box 1700
Jackson, MS 39215-1700
(601) 354-6657
1-800-626-7739 in state
Kenneth V. Miller
Bureau of Radiological Health
Missouri Department of Health
1730 last Elm
P.O. Box 570
Jefferson City, MO 65102
(314) 751-6083
1-800-669-7236 In State
Adrian C. Howe
Occupational Health Bureau
Montana Department of Health and
Environmental Sciences
Cogswell Building A113
Helena, MT 59620
(406)444-3671
Joseph Milone
Division of Radiological Health
Nebraska Department of Health
301 Centennial Mall, South
P.O. Box 95007
Lincoln, NE 68509
(402)471-2168
1-800-334-9491 In State
Stan Marshall
Department of Human Resources
505 East King Street
Room 203
Carson City, NV 89710
(702) 687-5394
New Hampshire David Chase
Bureau of Radiological Health
Division of Public Health Services
Health and Welfare. Building
Six Hazen Drive
Concord, NH 03301
(603) 271-4674 .
1-800-852-3345 x4674
Nebraska
New-Jersey Tonalee Carlson Key
Division of Environmental Quality
Department of Environmental
Protection
CN415
Trenton, NJ 08625-0145
(609) 987-6369
1-800-648-0394 in state
New Mexico William M. Floyd
Radiation Licensing and Registration
Section
New Mexico Environmental
Improvement Division
1190 Sf. Francis Drive
Santa Fe,NM 87503
(505) 827-4300
New York William J. Condon
Bureau of Environmental Radiation
Protection
New York State Health Department
Two University Place
Albany, NY 12202
(518)458-6495
1-800-458-1158 in state
North Carolina Dr. Felix Fong
Radiation Protection Division
Department of Environmental Health '
and Natural Resources
701 Barbour Drive
Raleigh, NC 27603-2008 '
(919) 571-4141
1-800-662-7301 (recorded info x4196)
North Dakota Arlen Jacobson
North Dakota Department of Health
1200 Missouri Avenue, Room 304
P.O. Box 5520
Bismarck, ND 58502-5520
(701)221-5188
Ohip Marcie Matthews
Radiological Health Program
Department of Health
1224 Kinnear Road - Suite 120
Columbus, OH 43212
(614)644-2727
1-800-523-4439 in state
n-30 Reprinted from USGS Open-File Report 93-292
-------
Oklahoma
Oregon
Pennsylvania
PuertoRico
Rhode Island
South Carolina
Gene Smith
Radiation Protection Division
Oklahoma State Department of
Health
P.O. Box 53551
Oklahoma City, OK 73152
(405) 271-5221
George Toombs ' ',
Department of Human Resources
Health Division
1400 SW 5th Avenue
Portland, OR 87201
(503)7314014
, Michael Pyles
Pennsylvania Department of
Environmental Resources
Bureau of Radiation Protection
, P.O. Box 2063 ' .
Harrisburg, PA 17120
(717)783-3594
1-800-23-RADON In State
David Saldana
Radiological Health Division
G.P.O. Call Box 70184
Rio Kedras, PuertoRico 00936
(809)767-3563,
Edmund Arcahd
Division of Occupational Health and
.Radiation
Department of Health
205 Cannon Building
Davis Street
Providence, RI02908 ' , '
(401)277-2438. . .
Bureau of Radiological Health
Department of Health and
Environmental Control
2600 Bull Street
Columbia, SC 29201
(803)734-4631
1-800-768-0362 ,
Sooth Dakota MikePoehop
Division of Environment Regulation
Department of Water and Natural
Resources :
Joe Foss Building, Room 217
523 E. Capitol
, Pierre, SD 57501-3181
(605) 773-3351,
i \ - ...
Tennessee Susie Shimek
Division of Air Pollution Control
Bureau of the Environment
Department of Environment and
Conservation " ,
Customs House, 701 Broadway
. Nashville, TN 37219-5403
(615) 532-0733
1-800-232-1139 in state
Gary Smith
Bureau of Radiation Control
Texas Department of Health
1100 West 49th Street
Austin, TX 78756-3189
(512) 834-6688
Utah John Hultquist '
Bureau of Radiation Control
Utah State Department of Health . ,-
. '. . 288North, 1460West
P.O. Box 16690 -
Salt Lake City, UT 84116-0690
(801) 5364250
Vermont Paul demons
:' Occupational and Radiological Health
Division ,',
Vermont Department of Health
' 10 Baldwin Street
Montpelier, "VT 05602
(802)828-2886
1-800-640-0601 in state
Virgin Islands Contact the U.S. Environmental
Protection Agency, Region II ,
in New York
(212)2644110
11-31 Reprinted from USGS Open-File Report 93-292
-------
Virginia Shelly Ottenbrite
Bureau of Radiological Health
Department of Health
109 Governor Street
Richmond, VA 23? \9
(804) 786-5932
1-800-468-0138 in state
Washington KateColeman
Department of Health
Office of Radiation Protection
Airdustrial Building 5, LE-13
Olympia,WA 98504
(206)7534518
1-800-323-9727 In State
West Virginia BeattieL. DeBord
Industrial Hygiene Division
West Virginia Department of Health
151 llth Avenue
South Charleston, WV 25303
(304) 558-3526
1-800-922-1255 In State
Wisconsin Conrad Weiffenbach
Radiation Protection Section
Division of Health
Department of Health and Social
Services
P.O. Box 309
Madison, WI53701-0309.
(608) 267-4796
1-800-798-9050 in state
Wyoming Janet Hough
Wyoming Department of Health and
Social Services
Hathway Building, 4th Floor
Cheyenne, WY 82002-CT710
(307) 777-6015
1-800-458-5847 in state
11-32 Reprinted from USGS -Open-File Report 93-292
-------
STATE GEOLOGICAL SURVEYS
May, 1993
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Ernest A. Mancini
Geological Survey of Alabama
P.O. Box 0
420 Haekberry Lane
Tuscaloosa, AL 35486-9780
(205)349-2852
Thomas E. Smith
Alaska Division of Geological &
Geophysical Surveys
794 University Ave., Suite 200
Fairbanks, AK 99709-3645
(907)479-7147
Larry D. Fellows
Arizona Geological Survey
845 North Park Ave., Suite 100
Tucson, AZ 85719
(602)882-4795
Norman F. Williams
Arkansas GeoIogical,Commission
Vardelle Parham Geology Center
3815 West Roosevelt Rd.
Little Rock, AR 72204
(501) 324-9165 -
James F. Davis
California Division of Mines &
Geology
801 K Street, MS 12-30
Sacramento, CA 95814-3531
(916)445-1923
Pat Rogers (Acting)
Colorado Geological Survey
1313 Sherman St., Rm 715
Denver, CO 80203
(303)866-2611 '
** , .
Richard C. Hyde
Connecticut Geological & Natural
History Survey
165 Capitol Ave., Rm. 553
Hartford, CT 06106
(203)566-3540
Robert R. Jordan
Delaware Geological Survey
University of Delaware
101 Penny Hall
Newark, DE 19716-7501
(302) 831-2833
Walter Schmidt
Florida Geological Si vey
903 W*. Tennessee St
Tallahassee, FL 32304-7700
(904)4884191
Georgia William H.,McLemore
Georgia Geologic Survey
" Rm. 400
19 Martin Luther King Jr. Drl SW
Atlanta, GA 30334 -
(404)656-3214
Hawaii Manabu Tagomori
Dept. of Land and Natural Resources
Division of Water & Land Mgt
P.O. Box 373
Honolulu, HI
(808)548-7539 '
Idaho Earl H. Bennett
. Idaho Geological Survey
University of Idaho
Morrffl Hall, Rm. 332
Moscow, ID 83843
(208) 885-7991 . .
Illinois Morris W. Leighton
Illinois State Geological Survey
Natural Resotte^a-Building
615 East Peabody Dr.
Champaign, IL 61820
(217)333-4747 . ;.
Indiana Norman C. Hester
Indiana Geological Survey
611 North Walnut Grove
Bloomington, M47405
(812) 855-9350 .
Iowa Donald L. Koch
Iowa Department of Natural Resources
Geological Survey Bureau
109 Trowbridge Hall
Iowa City, IA 52242-1319
. (319) 335-1575
Kansas LeeC.Gerhard
Kansas Geological Survey
1930 Constant Ave., West Campus
University of Kansas
Lawrence,KS 66047.
(913)864-3965 *
II-33 Reprinted from USGS Open-File Report 93-292
-------
Mains
Michigan
Minnesota
Mississippi
Donald C. Haney
Kentucky Geological Survey
University of Kentucky
228 Mining & Mineral Resources
Building
Lexington, KY 40506-0107 .
(606)257-5500
"William E. Marsalis
Louisiana Geological Survey "
P.O. Box 2827
University Station
Baton Rouge, LA 70821-2827
(504)388-5320
Walter A, Anderson
Maine Geological Survey
Department of Conservation
State House, Station 22
Augusta, ME 04333
(207)289-2801
Emery T. Cleaves
Maryland Geological Survey
2300 St. Paul Street
Baltimore, MD 21218-5210
(410) 554-5500
Joseph A. Sinnott
Massachusetts Office of
Environmental Affairs
100 Cambridge SL, Room 2000
Boston, MA 02202
(617)727-9800
R. Thomas Segall
Michigan Geological Survey Division
Box 30256
Lansing, Ml 48909
(517) 334-6923
Priscilla C'Grew
Minnesota Geological Survey
2642 University Ave.
St. Paul, MN 55114-1057
(612) 627-4780
S. Cragin Knox
Mississippi Office of Geology
P.O. Box 20307
Jackson, MS 39289-1307
(601)961-5500
Missouri James H. Williams
Missouri Division of Geology St.
Land Survey
111 Fairgrounds Road
P.O. Box 250
Rolla, MO 65401
(314) 368-2100
Montana Edward T.Ruppel
Montana Bureau of Mines & Geology
Montana College of Mineral Science
and Technology, Main Hall
Butte, MT 59701
(406)496-4180
Nebraska Perry B. Wigley
Nebraska Conservation & Survey
Division
113 Nebraska Hall
University of Nebraska
Lincoln, ME 68588-0517
(402)472-2410
Nevada Jonathan G. Price
Nevada Bureau of Mines & Geology
Stop 178
University of Nevada-Reno
Reno, NV 89557-0088
(702)784-6691
New Hampshire Eugene L. Boudette
Dept. of Environmental Services
117 James Hall
University of New Hampshire
' Durham, NH 03824-3589
(603)862-3160
Newlersey Haig F. Kasabach
New Jersey Geological Survey
P.O. Box 427
Trenton, NJ 08625
(609)292-1185
NewMexico Charles E, Chapin
New Mexico Bureau of Mines &
Mineral Resources
Campus Station
Socorro.NM 87801
(505) 835-5420
New York Robert H. Fakundiny
New York State Geological Survey
3136 Cultural Education Center
Empire State Plaza
Albany, NY 12230
(518)474-5816
11-34 Reprinted from USGS Open-File Report 93-292
-------
North Carolina Charles HL Gardner
North Carolina Geological Survey
P.O. Box 27687
Raleigh, NC 27611-7687
. (919)733-3833
North Dakota John P. Bluemle
North Dakota Geological Survey
eOOEastBlvd.
Bismarck, ND 58505-0840
(701)224-4109
Ohio . Thomas M. Berg
Ohio DepL of Natural Resources
' Division of Geological Survey
4383 Fountain Square Drive
Columbus, OH 43224-1362
(614)265-6576 "
Oklahoma Charles J. Mankin
Oklahoma Geological Survey
Room N-131, Energy Center
100E.Boyd .
Norman, OK 73019-0628
(405)325-3031
Donald A. Hull
Dept. of Geology & Mineral Indust.
Suite 965
800 NE Oregon St. #28
Portland, OR 97232-2162
(503)731-4600 "
Pennsylvania Donald M. HosMns
Dept. of Environmental Resources
Bureau of Topographic & Geologic
Survey ,
P.O. Box 2357
Harrisburg, PA 17105-2357
(717)787-2169 ,
Puerto Rico Ramdn M. Alonso
Puerto Rico Geological Survey
Division
Box 5887
Puerta de Tierra Station
San Juan, P.R. 00906
(809)722-2526
Rhode Island J. Allan Cain
Department of Geology
University of Rhode Island
315GreenHall
Kingston, RI02881
(401)792-2265
South Carolina Alan-Jon W. Zupan (Acting)
South Carolina Geological Survey
5 Geology Road
Columbia, SC 29210-9998
(803)737-9440
South Dakota C.M. Christensen (Acting)
South Dakota Geological Survey
Science Center
University of South Dakota
VermilUon, SD 57069-2390
(605) 677-5227
Tennessee Edward T.Luther
Tennessee Division of Geology
13th Floor, L & C Tower
401 Church Street
- Nashville, TN 37243-0445
(615)532-1500
Texas William L. Fisher
Texas Bureau of Economic Geology
University of Texas
University Station, Box X
Austin, TX 78713-7508
(512)471-7721 ,
Utah M. Lee Allison
Utah Geological & Mineral Survey
2363 S'. Foothm Dr.
, Salt Lake City, UT 84109-1491
1 (801)467-7970
Diane L. Conrad
Vermont Division of Geology and
Mineral Resources
103 South Main St.
Waterbury.VT 05671
(802)244-5164
Virginia Stanley S- Johnson
Virginia Division of Mineral
Resources
P.O. Box 3667
Charlottesville, VA 22903
(804)293-5121
Washington Raymond Lasmanis
Washington Division of Geology &
Earth Resources
Department of Natural Resources
P.O. Box 47007
. Olympia, Washington 98504-7007
(206)902-1450
11-35 Reprinted from USGSOpen-Ffle Report 93-292
-------
West Virginia Larry D. Woodfork
West Virginia Geological and
Economic Survey
Mont Chateau Research Center
P.O. Box 879
Morgantown, WV 26507-0879
(304)594-2331
Wisconsin James Robertson
Wisconsin Geological & Natural
History Survey
381? Mineral Point Road
Madison, WI 53705-5100
(608)263-7384
Wyoming Gary B. Glass
Geological Survey of Wyoming
University of Wyoming
Box 3008, University Station
Laramie, WY 82071-3008
(307) 766-2286
n-se
Reprinted fiom USGS Open-File Report 93-292
-------
EPA REGION 7 GEOLOGIC RADON POTENTIAL SUMMARY
. - . - by . - :_, -
R. Randall Schumann, James K. Otton, and Sandra L. Szarzi
U.S. Geological Survey '
EPA Region 7 includes the states of Iowa, Kansas, Missouri, and Nebraska. For each
state, geologic radon potential areas were delineated and ranked on the basis of geologic, soil, .
housing construction, and other factors. Areas in which the average screening indoor radon level
of all homes within the area is estimated to be greater than 4 pCi/L were ranked high. Areas in
which the average screening indoor radon level of all homes within the area is estimated to be
between 2 and 4 pG/L were-ranked moderate/variable, and areas in which the average screening
indoor radon level of all homes within the area is estimated to be less than 2 pCi/L were ranked
low. Information on the data used and on the radon potential ranking scheme is given in the
introduction chapter. More detailed information on the geology and radon potential of each state in
Region 7 is given in the individual state chapters. The individual chapters describing the geology
and radon potential of the four states in EPA Region 7, though mueh more detailed than this
summary, still are generalized assessments and there is no substitute for having a home tested.
Radon levels, both high and low, can be-quite localized, and within any radon potential area homes
with indoor radon levels both above and below the predicted average win likely be found.
Figure 1 shows the geologic radon potential areas in EPA Region 7. Figure 2 shows -
average screening indoor radon levels in EPA Region 7 by county. The data for each state are
from the State/EPA Residential Radon Survey and reflect screening charcoal canister
measurements. Figure 3 shows the geologic radon potential of areas in Region 7, combined and
summarized from the individual state chapters. Many rocks and soils in EPA Region 7 contain
ample radon source material (uranium and radium) and have soil permeabilities sufficient to
produce moderate or high radon levels in homes. YThe following sections summarize the geologic-
radon potential of each of the four states in Region 7. More detailed discussions may be found in
the individual state radon potential chapters for the states in Region 7. ,.'""
IOWA / '
Pre-Elinoian-age glacial deposits cover most of Iowa, and are at or near the surface in the
southern, northwestern, and much of the northeastern parts of the state. These deposits generally
consist of calcium-carbonate-rich loam and clay loam till containing pebbles arid cobbles of granite,
gabbro, basalt, rhyolite, greenstone, quartzite, chert, diorite, and limestone. Pre-IUinoian tills are
covered by from less than 1 m to more than 20 m of Wisconsinan loess (windblown silt) in
western, southern, and eastern Iowa. Dlinoian glacial deposits occur a relatively small area along
the Mississippi River in southeastern Iowa. These deposits consist of loamy to locally sandy till
containing clasts of limestone and dolomite, with lesser amounts of igneous and metamorphic
rocks, sandstone, and coal fragments, fllinoian deposits are covered by 1-5 m of loess.
Wisconsinan drift is,represented by the Gary and Tazewell drifts, consisting of calcareous loamy
till containing clasts of shale, limestone, and dolomite, with minor amounts of basalt, diabase,
granite, chert, and sandstone. Gary drift (now called the Dows Formation),%hioh represents
deposits of the Des Moines lobe, is generally not loess-covered; Tazewell drift is covered by as
much as 2 m of loess. ' . -
, ffl-1 Reprinted from USGS Open-File Report 93-292-G
-------
Figure 1. Geologic radon potential areas of EPA Region 7. See text for discussion of areas. 1,6-Pierre Shale; 2,5-Tertiary-
sedimentary rocks; 3-Sand Hills; 4,8,1l-Tertiary sedimentary rocks covered by varying thicknesses of loess; 7,13,16,21,23-loess-
covered glacial drift plains; 9-Cretaceous sedimentary rocks covered by varying thicknesses of loess; 10-dune sands in the Arkansas and
Cimarron river valleys; 12,15-area underlain by Pennsylvanian and Permian rocks; 14-part of the Mid-Gontinent Rift Zone; 17,22-
loess and glacial deposits along the Missouri River; 18-Des Moines lobe; 19-Iowan Surface; 20-Paleozoic Plateau; 24-unglaciated part
of the Osage Plain; 25-Qzark Plateau; 26,28-Area underlain by carbonate rocks; 27-St Francois Mountains; 29,-Coastal Plain.
-------
Indoor Radon Screening .
Measurements: Average (pCI/L)
69
148
35
0.0 to 1,9
4.1 to 9.9
10.0 to 23.2
48 f'l") - Missing Data (< 5 measurements)
Figure 2, Average screening indoor radon levels by county for EPA Region 7. Data from the State/EPA Residential Radon
Survey. Histograms in map legend indicate the number of counties in each measurement category.
-------
>A - *.*<*.' "«s.1 *.*.*-t *A *.*».' *.*.*iV»A.v*.'. *» sA.*..!« -"Jb.ljAC*»* *t
GEOLOGIC RADON POTENTIAL (average sreening indoor radon level):
| | LOW (<2 pCf/L) ^ MODERATE/VARIABLE (2-4 pCi/L) ^ HIGH (> 4 pCi/L)
Figure 3. Geologic radon potential of EPA Region 7. Ranges next to each category label indicate the
predicted average screening indoor radon level for all homes in each area.
-------
The aeroradioactivity signature of surface deposits in Iowa, especially the Des Moines lobe
deposits and other areas in which the loess cover is dicontinuous or absent, seems lower than
would be expected in light of the elevated indoor radon levels. This may be because much of the
radium in the near-surface soil horizons may have been leached and transported downward in the
soil profile, giving a low surface radiometric signature while generating significant radon at depth
(1-2 m? or greater) to produce elevated indoor radon levels. For example, a large area of low
radioactivity (<1,5 ppm eU) in the northern part of the State corresponds roughly to the Des
Moines lobe and the lowan erosion surface, an area directly east of the Des Moines, lobe in
northeastern Iowa that is underlain by Pre-IUinoian glacial deposits and loess. However, these
areas have high geologic radon potential. Most of the remainder of the State has eU values in the,
1.5-2.5 ppm range. In general, soils developed from glacial deposits can be more rapidly leached
of mobile ions than their bedrock counterparts, because crushing and grinding of the roeks,by
glacial action gives soil weathering agents (mainly moisture), better access to soil and mineral grain
surfaces. Grinding of the rocks increases the mobility of uranium and radium in the soils by t
exposing them at grain surfaces, enhancing radionucHde mobility and radon emanation. In
addition, poorly-sorted glacial drift may in many cases have higher permeability than the bedrock
from which it is derived; Cracking of clayey glacial soils during dry periods can create sufficient
permeability for convective radon transport to occur. This may be an important factor causing -
elevated radon levels in areas underlain by clay-rich glacial deposits.
Loess-covered areas have a higher radiometric signature than loess-fee areas, and also
appear to correlate roughly with higher average indoor radon levels than loess-free areas, although
all areas of Iowa have average indoor radon levels exceeding 4 pCi/L., The Loess-Covered Drift -
Plains, which cover northwestern Iowa and all of southern Iowa, are underlain by Pre-IUinoian .
and Illinoian glacial deposits, and loess. The Loess-Covered Drift Plains have overall high radon
potential Valley bottoms with wet soils along the Mississippi and Missouri Rivers may have
locally moderate to low radon potential because the gas permeability of the soils is extremely low
due to the water filling the pore spaces.' ,
The Paleozoic Plateau, in northeastern Iowa, is underlain primarily by Ordovician
carbonate and Cambrian sandstone bedrock covered by varying amounts of Quaternary glacial
deposits and loess. It was originally thought to have been unglaciated because it is deeply
dissected and lacks glacial landforms. However, small patches of Pre-Dlinoian drift have been
preserved on uplands, indicating that at least part of the area had been glaciated. The Paleozoic
Plateau also has high geologic radon potential. Soils developed from carbonate rocks are derived
from the residue that remains after dissolution of the calcium carbonate that fnakes.up the majority
of the rock, including heavy minerals and metals such as uranium, and thus they may contain
somewhat higher concentrations of uranium or uranium-series radionuclides than the parent rock.
Residuum from weathered carbonate rocks may be a potential radon source if a structure is built on
such a residual soil, or if the residuum constitutes a significant part of a till or other surficial
deposit In some areas underlain by carbonate bedrock, solution features such as sinkholes and :
caves increase the overall permeability of the rocks in these areas and generally increase the radon
potential of these rocks, but few homes are built directly over major solution features.
KANSAS .. .. - . . . ;..-..' ,." ; , ,
Almost all of the bedrock exposed at the surface in Kansas consists of sedimentary units
ranging in age from Mississippian to Quaternary. Igneous rocks native to Kansas and exposed at
, ffl-5 Reprinted from TJSGS Open-File Report 93-i92-G
-------
the surface are small localized exposures of Cretaceous lamproite in Woodsoa County and
Cretaceous Mmberlte in Riley County. Sedimentary rocks of Mississippian age underlie the
extreme southeastern corner of the State, They consist primarily of limestones but also include
shale, dolomite, chert, sandstone, and siltstone. Pennsylvanian rocks underlie approximately the
eastern one-quarter of the State. They consist of an alternating sequence of marine and nonmarine
shale, limestone, sandstone, and coal, with lesser amounts of chert and conglomerate. The shales
range from green and gray (low organic content) to black (organic rich). Permian rocks are
exposed in east-central and southern Kansas and consist of limestone, shale, gypsum, anhydrite,
chert, siltstone, and dolomite. Red sandstone and shale of Permian age underlie the Red Hills
along the southern border of Kansas. . .
The Mississippian, Pennsylvanian, and Permian rocks in eastern Kansas have relatively
low uranium contents, generally low to moderate permeability and have generally low to moderate
geologic, radon potential. Homes situated on Pennsylvanian and Permian carbonate rocks
(limestones and dolomites) may have locally elevated indoor radon levels if the limestones have
developed clayey residual soils and(or) if solution features (karst topography), are present in the
area. Because of the geologic variability of these units, the Mississippian, Pennsylvanian, and
Permian rock outcrop area has been ranked moderate or variable in overall geologic radon
potential. Homes sited on Pennsylvanian black shale units may be subject to locally high indoor
radon levels. This may be the in the Kansas City area, part of which is underlain by black
shales.
Some elevated indoor radon levels in the northern part of the Permian outcrop area,
specifically in Marshall, Clay, Riley, Geary, and Dickinson Counties, may be related to faults and
fractures of the Mid-Continent Rift and Nemaha Uplift Many of the subsurface faults reach and
displace the surface sedimentary rock cover, and the density and spacing of faults and fractures .
within the rift zone is relatively high. Fault and shear zones are commonly areas of locally elevated
radon because these zones typically have higher permeability than the surrounding rocks, because
they are preferred zones of uranium mineralization, and because they are potential pathways
through which uranium-, radium-, and(or) radon-bearing fluids and gases can migrate.
Cretaceous sedimentary rocks underlie much of north-central and central Kansas,.and
consist of green, gray, and black, shale, sandstone, siltstone, limestone, chalk, and chalky shale.
A discontinuous layer of loess of varying thickness covers the Cretaceous rocks in many areas,
particularly in the western part of the Cretaceous outcrop area. Cretaceous rocks in Kansas contain
sufficient uranium to generate elevated indoor radon levels. Soils developed on Cretaceous rocks
have low to moderate permeability, but the shale-derived soils with low permeability to water likely
have moderate permeability to soil gas when they are dry due to desiccation cracks. Areas
underlain by these rocks have an overall high radon potential. Tertiary rocks cover much of
western Kansas, though they are covered by loess deposits in many areas. Tertiary rocks consist
of nonmarine sandstone, siltstone, and shale; volcanic ash deposits; and unconsolidated gravel,
sand, sUt, and clay. Areas underlain by the Tertiary Ogalala Formation have a-moderate
radioactivity signature and a moderate to high radon potential.
Loess ranging from 0 to more than 30 meters in thickness covers as much as 65 percent of
the surface of Kansas and is thickest and most extensive in the western and north-central parts of
the State and in proximity to glacial deposits in the northeastern corner of the State. Possible
sources for the loess include: (1) glacial outwash, (2) sand dunes in the Arkansas and Cimarron
River valleys or elsewhere (such as the Sand Hills of Nebraska), and (3) erosion of Tertiary
sedimentary rocks by wind and rivers. Radon potential of loess-mantled areas depends on the
ffl-6 Reprinted from USGS Open-File Report 93-292-O
-------
thickness and source of the loess. In areas of very thin-loess cover, the radpn potential of the
underlying bedrock is significant, and the loess both generates radon and transmits radon from the
underlying bedrock, whereas if the loess is more than 7-10 m thick, it is probably the sole radon
source for homes in the area. Loess-covered areas underlain by Cretaceous and Tertiary bedrock
appear to have variably moderate to high radon potential across the State, and locally elevated
indoor radon levels may be expected anywhere within areas underlain by these units. Areas
underlain by loess-covered Pennsylvanian and Permian rocks appear to generate mainly moderate
to locally elevated indoor radon levels. .
Areas of windblown sand in the Arkansas and Cimarron River valleys have low uranium
contents and low radon potential, but few homes are built directly oh the sand dunes. The dune
sands are intermixed with loess in parts of the Arkansas and Cifnarron valleys, and the radon
potential may be related to the relative proportions of sand, loess, and bedrock within these areas.
, Areas underlain by dune sand are expected to have lower radon levels, areas with considerable
loess content are expected to have moderate to locally elevated radon levels. Where sand or loess
is thin or absent, the radon levels in homes on Tertiary or Cretaceous bedrock are also expected to
generally fall into the moderate to high category. / , - "
The area within the glacial limit in northeastern Kansas is underlain by discontinuous
glacial drift and loess. The glacial deposits consist of a clay, silt,, or sand matrix with cobbles and
boulders of igneous and metamorphic. rocks derived from as far away as the Lake Superior Region
and southwestern Minnesota. The glacial deposits are discontinuous and till thickness varies
markedly within the area, most likely because post-glacial erosion has, removed and redistributed
significant amounts of drift. Because the loess in this area is likely derived from nearby glacial
drift, and because glacial deposits are known to generate elevated indoor radon levels throughout
the northern Great Plains, this area should be considered to have a moderate to locally high radon,
potential. "
MISSOURI .. ' . -..-,.."
Missouri lies within the stable midcontinent area of the United States. The dominant
geologic feature is the Ozark uplift in the southeastern part of the state which forms the Ozark
Plateau Province. Precambrian crystalline rocks form the core of the uplift and crop out along its
eastern side. Paleozoic sedimentary rocks dip away from this core in all directions. To the north,
northwest, and west of the uplift these sedimentary sequences are folded into broad arches and
sags. The Preeambrian core of the Ozark uplift is primarily granite and rhyolite. Much of this rock
is slightly enriched in uranium. (2.5-5.0 ppm); The Preeambrian core is surrounded by Cambrian
and Ordovician sandstone, dolostone, shale, cherty dolostone, chert, and limestone.
Pennsylvanian sandstone, shale and clay crop out in the north-central part of the uplift To the
north and west of the uplift^ Mississippian and Pennsylvanian shale, limestone, sandstone, clay,
coal, and fire clay occur. Silurian and Devonian sedimentary rocks crop out in central Missouri
along the Missouri River and along the Mississippi River northeast of St Louis and in Cape
Girardeau and Perry Counties south of St. Louis. '..'.
Uraniferous granites and rhyolites, and residuum developed on carbonate rocks in the
Ozark Plateau Province are likely to have significant percentages of homes with indoor radon levels
exceeding 4 pCi/L. The most likely areas are those where elevated eU values occur. Where
structures, are sited on somewhat excessively drained soils in this area the radon potential is further
increased. Extreme indoor radon levels may be expected where-structures are sited on uranium
m-7 Reprinted from USGS Open-File Report 93-292-G
-------
occurrences and where the disturbed zone around a foundation is connected to solution openings in
carbonate rocks or to open zones in soil and bedrock caused by mine subsidence.
The Ozark Plateau Province has a moderate overall radon potential. Several areas of
somewhat excessively drained soils, scattered uranium occurrences, residual carbonate soils in
which uranium has been concentrated, and areas of karst may generate locally elevated indoor
radon levels in this area. The St Francois Mountains have high radon potential owing to elevated
levels of uranium in soils developed on granitic and volcanic rocks throughout these mountains and
substantial areas of somewhat excessively to excessively drained soils.
The permeability of soils and subsoils in karst areas has been enhanced by solution
openings in and near carbonate pinnacles and by zones of solution collapse. Where soils
developed on such carbonate rocks are thin, foundations may encounter open bedrock fractures in
the limestone. Karst underlies parts of the City and County of St Louis and may locally cause
elevated indoor radon levels. Elevated eU and significant karst development occur in Perry and
Cape Girardeau Counties. Structures sited on locally highly permeable karst soils with elevated eU
in these two counties will likely have elevated indoor radon levels. Broad karst areas have formed
by dissolution of carbonate rocks in the central and western Ozark Plateau, the southern Osage
Plain, and along the Mississippi River from Cape Girardeau County to Rails County. These
carbonate regions have overall moderate radon potential. However, areas of intense karst
development, elevated uranium in residual soils developed on carbonate, and large areas of
somewhat excessively drained to excessively drained soils may cause locally high indoor radon
levels to occur.
Several very thin, highly uraniferous (as much as 180 ppm), black, phosphatic shales
occur in the Devonian and Pennsylvanian sedimentary rock sequences in the unglaciated Osage
Plain of southwestern Missouri. Elevated indoor radon levels may be expected where the
foundations of structures intercept the thin Pennsylvanian uraniferous shales or the Chattanooga
Shale in the southwestern part of the state from Kansas City south to McDonald and Barry
Counties and in north-central Missouri in Boone, Randolph and Macon Counties, or where they
intercept well-drained alluvium derived from these rocks. Because these uraniferous shales are so
thin, such circumstances are likely to be very site- or tract-specific; thus detailed geologic and soil
mapping will be necessary to outline areas of potential problems. Where these shales are jointed or
fractured or soils formed on them are somewhat excessively drained on Mllslopes, the radon
potential is further increased. Residuum developed on limestones associated with these
uraniferous shales may also have elevated uranium levels and have significant radon potential. The
unglaciated Osage Plain province has a low overall radon potential; however, areas of thin soils
underlain by the uraniferous shales in this province have high radon potential with locally extreme
values possible.
Along the Missouri and Mississippi River valley floor, alluvial deposits (silt, sand, and
gravel) dominate. Loess deposits occur on the flanks of the river valleys in several areas and are
especially widespread in Platte, Buchanan, Holt, and. Atchison Counties along the Missouri River
north of Kansas City. Alluvium and loess along the upper Missouri River Valley upstream from
Kansas City seem to be producing elevated indoor radon levels that may be related to the somewhat
elevated uranium content of these materials and, possibly, to elevated radon emanation and
diffusion associated with well-drained loe'ss deposits. Detailed studies of indoor radon data in this
area would be necessary to determine more closely the origin of elevated indoor radon levels.
Thin, somewhat excessively drained soils developed on limestone that occur as" part of one soil
m-8 Reprinted from USGS Open-File Report 93-292-G
-------
association in the southern suburbs of Kansas City may also be telated to elevated indoor radon
levels in Jackson County,
The northernmost part of the Mississippi Embayment occupies the southeastern corner of
the state and forms the Coastal Plain Province, or southeastern lowlands. This area is underlain by
Tertiary and Quaternary alluvium. The Coastal Plain Province has a low radon potential overall.
Only one value exceeding 4 pCi/L is reported for a six-county area, and very poorly drained soils
are widespread. However, some aeroradiometrie anomalies occur in this area, and some
excessively drained soils occur locally. Elevated indoor radonlevels may be associated with these
locales. Although elevated elJ occurs over some of the sedimentary rocks in this province, the
high soil moisture, the very poorly drained soils, and the low indoor radon values all point towards
low radon potential
The surficial geology north of the Missouri River is dominated by glacial deposits covered .
with a thin veneer of loess; hpwever, several areas of residual soils developed on underlying
sedimentary rocks occur in the eastern and western parts of this region. Residual soils are those
soils formed by weathering of the material beneath the soil. These surficial deposits (both glacial'
deposits and residuum) are generally 50-200 feet thick, but they locally exceed 200 feet aJbhg the
northern edge of the state. The dissected till plain of northern Missouri has moderate overall radon
potential, although elevated indoor radon levels are common in areas of similar geology in adjacent
states, particularly Iowa, Nebraska (fig, 1), and Illinois. Except for counties along the Missouri
River, the indoor radon data for the counties in the dissected till plain are sparse and appear to be
generally in the low to moderate range. . ,. » ,
NEBRASKA , ,
Rocks ranging in age from Pennsylvanian to Quaternary are exposed in Nebraska.
Pennsylvanian rocks are exposed in southeastern Nebraska and include limestones, shales, and
sandstones. Only some of the Upper Pennsylvanian strata are exposed in Nebraska; these rocks
are a repeated sequence of marine shales and limestones alternating with nonmarine sandstones and
shales, and thin coals. Exposed Permian rocks consist of green, gray, and red shales, limestone,
and gypsum. Exposures of Pennsylvanian arid Permian rocks are generally limited to valley sides
along streams because much of the eastern part of the State is mantled with Pleistocene .glacial
deposits and loess. Black shales of Pennsylvanian age may constitute a significant radon source
where the shales are a source component of the glacial tills.
Cretaceous rocks are exposed in' much of eastern Nebraska, in parts of northern and
northwestern Nebraska, and along the Republican River Valley. Lower Cretaceous rocks consist
of sandstones, shales, and thin coals. Upper Cretaceous rocks consist primarily of shale, , >
limestone, and sandstone. The Upper Cretaceous Pierre Shale consists of gray, brown, and black
shales, with thin layers of bentohite, chalk, limestone, and sandstone. Although the permeability
of soils developed on the Pierre Shale is listed as low, the shales contain numerous fractures and
partings and are likely to have sufficient permeability for radon transport during dry periods. The
stratigraphically lowest unit in the Pierre Shale is the Sharon Springs Member, a black shale of
widespread occurrence in Nebraska, South Dakota, Kansas, and Colorado. The Sharon Springs
Member is exposed in a relatively broad area along the Niobrara and Missouri Rivers from Keya
Paha to Cedar Counties and along the Republican River in southern Nebraska. -The gray-shale
units of the Pierre Shale, while not as urariiferous as the black shale of the Sharon Springs
Member, generally contain higher-than-average (i.e., >2.5 ppm) amounts of uraniura,and are
m-9 Reprinted from USGS Open-File Report 93-292-G
-------
correlated with elevated indoor radon levels in several areas. Outcrops of the Pierre Shale in the
northwestern comer of Nebraska have the highest surface radioactivity in the State. Areas
underlain by Cretaceous rocks, particularly the Pierre Shale, have overall high radon potential.
Tertiary rocks have the most widespread exposure in the State. The White River Group
consists of mudstone, siltstone, sandstone, and thin layers of volcanic ash, and is exposed in the
North and South Platte valleys and in northwestern Nebraska. The Arikaree Group overlies the
White River Group and consists of siltstone and sandstone. The Tertiary Ogallala Group covers
about two-thirds of the State. It consists of sandstone, siltstone, gravel, sand, silt, clay, and thin
volcanic ash layers. The Ogallala is covered by the Sand Hills, an area of Quaternary windblown
sand deposits, in the north-central part of Nebraska. Pre-Sand Hills sediments of Pliocene and
Quaternary age also overlie portions of the Ogallala in this area. The Ogallala, Arikaree, and White
River Groups all have high surface radioactivity (for purposes of this report, high radioactivity is
defined as greater than 2.5 ppm eU) and are known to host uranium deposits. Soils developed on
the Tertiary units have moderate permeability and generate moderate to locally high indoor radon.
The White River and Arikaree Groups have significant amounts of uranium-bearing volcanic glass
and may be somewhat more likely to generate elevated indoor radon concentrations. Areas
underlain by Tertiary sedimentary rocks have overall moderate radon potential. Some homes in
this area are likely to have high indoor radon levels, particularly those sited on uranium-bearing
parts of the White River and Arikaree Groups in northwestern Nebraska.
. Eastern Nebraska and southern Nebraska south of the Platte River are underlain by
Permian through Tertiary rocks mantled with Pleistocene glacial deposits of Pre-Dlinoian age and
loess. The glacial deposits generally consist of a clay, silt, or sand matrix with pebbles and
cobbles of limestone, igneous rocks, and quartzite. Source material for the glacial deposits :
includes locally-derived Permian and Perinsylvanian limestone and shale and Cretaceous sandstone
and shale, as well as lesser amounts of sandstone, limestone, shale, and igneous and metamorphic
rocks from bedrock sources to the north and northeast. Of the source rocks underlying the glacial
deposits and those to the north and northeast, Cretaceous sandstones and shales, Pennsylvania*)
black shales, and Precambrian crystalline rocks all contain sufficient amounts of uranium-series
radionuclides (uranium and(or) radium) to generate radon at elevated levels.
Loess covers most of the glacial deposits in eastern Nebraska as well as bedrock in the
south-central part of the State. Loess is a generally good radon source because it consists of silt
and clay-sized particles, which are more likely to be associated with radionuclides and have higher
emanation coefficients than larger sized particles, and it typically has moderate permeability.
Average indoor radon levels are consistently greater than 4 pCi/L in areas underlain by loess-
mantled glacial drift The majority of homes in the area underlain by loess-mantled bedrock in the
south-central .part of the State also have radon levels exceeding 4 pCi/L, but indoor radon levels
are likely to be more variable from house to house in south-central Nebraska, depending on the
distribution, thickness, or weathering extent of the loess. Areas underlain by glacial drift and most
areas underlain by loess have overall high radon potential. The area mapped as loess between the
Platte River and the Sand Hills in the central part of the State has generally moderate radon
potential. Homes sited on thicker loess along the north side of the Platte River in Dawson and
Buffalo Counties may have locally high indoor radon levels. The Sand Hills have low surface
radioactivity and generally low radon potential.
m-10 Reprinted from USGS Open-File Report 93-292-G
-------
' PRELIMINARY GEOLOGIC RADON POTENTIAL ASSESSMENT OF KANSAS
'..': - ';;- by" '' "'. ' ' :
R. Randall Schumann
U.S. Geological Survey
INTRODUCTION '/*'
Many of the rocks and soils in Kansas have the potential to generate levels of indoor radon
exceeding the U.S. Environmental Protection Agency's guideline of 4 pCi/L. In a survey ?of 2009
homes conducted during the winter of 1987-88 by the State of Kansas and the EPA, 25 percent of
the homes had indoor radon levels exceeding, this value. At the scale of this evaluation, all areas in
Kansas have moderate/variable or high geologic radon potential.
This is a generalized assessment of geologic radon potential of rocks, soils, and surficial
deposits of Kansas. The scale of this assessment is such that it is inappropriate for use in
identifying the radon potential of small areas such as neighborhoods, individual building sites, or
housing tracts. Any localized assessment of radon potential must be supplemented with additional
data and information from the locality. Within any area of a given radon potential ranking, there
are likely to be areas with higher or lower radon levels than characterized for the area as a whole.
Indoor radon levels, both high and low, can be quite localized, and there is no substitute for testing
individual homes. Elevated levels of indoor radon have been .found in every-sfate, and EPA
-recommends that all homes be tested. For more information on radon, the reader is urged to
consult the local or State radon program or EPA regional office. More .detailed information on state
'or local geology may be obtained from the'State geological survey. Addresses and phone numbers
for these agencies are listed in chapter 1 of this booklet.
PHYSIOGRAPHIC AND GEOGRAPHIC SETTING
Kansas lies within .the Great Plains and Central Lowlands physiographic provinces Of the
United States. Within the State the landscape is subdivided into 11 physiographic areas (fig. 1 j.
The extreme southeastern comer of the State is part of the Ozark Plateau, in which beds of
limestone and chert form hills similar to those in Missouri and Arkansas. The Cherokee Lowlands
lie adjacent to the Ozark Plateau in southeastern Kansas. This area is relatively flat and poorly
drained because it is underlain by easily credible sandstones and shales. The Cherokee Lowlands
is a major coal-producing area. Underground mining for coal and metals occurred in the Cherokee
Lowlands and Ozark Plateau regions (Wilson, 1984). The Osage Cuestas (fig. 1) is an area of
parallel ridges, with a steep escarpment on their east sides and a gentle slope on their west sides, ,
formed by gently dipping, alternating resistant and soft rocks. The Chautauqua Hills extend ;
northward from the southern border of the State into the Osage Cuestas region. The Chautauqua
Hills are rolling uplands capped by sandstones and limestones (Steeples and Buchanan, 1983; .
Wilson, 1984). To the west of the Chautauqua Hills are the Flint Hills", grassy uplands formed on
limestone and chert with intervening lowlands underlain by shales. Because chert is more resistant
to erosion than limestone, the Flint Hills are significantly higher than the surrounding landscape
(Wilson, 1984), The Wellington-McPherson Lowlands lie west of, and adjacent to, the Flint Hills
(fig. 1). The Red Hills, along the central southern border of Kansas, are composed of red shale
and siltstone, called "red beds", capped by gray gypsum and dolomite, and are characterized by
butte-and-mesa topography (Wilson,. 1984). In Meade and Clark Counties, on the western border
IV-1 . Reprinted from USGS Open-File Report.93-292-G
-------
PIWI»I _J ou«
t \ . «:
.:;i: ";".!t '.-r
t~, ^H^-pKS
]; j;.-"]
so
ARKANSAS RIVER LOWLANDS
' WELLINGTON-MCPHERSON LOWLANDS
FLINT HILLS UPLANDS
CHAUTAUQUA HILLS
i
CHEROKEE LOWLANDS
O2ARK PLATEAU
100 miles
75 150 kilometers
OSAGE CUESTAS
GLACIATED REGION
HIGH PLAINS
RED HILLS
SMOKY HILLS
Figure 1. Physiographic regions of Kansas (from Wilson, 1984).
-------
of the Red Hills, sinkholes have formed from dissolution of the salt and gypsum beds underlying
the area. , ....''. !
The northeastern part of Kansas is a distinctive MEy region formed on Pleistocene glacial
deposits, called the glaciated region (fig. 1). In this area the rolling hills are covered by scattered
cobbles and boulders of crystalline rocks such as red Preeambrian quartzite from southern
Minnesota and northern Iowa (Wilson, 1984). The Smoky Hills occupy much of north-central
. Kansas (fig. 1). The eastern part of the Smoky Hills is characterized by sandstone hills and buttes '
that rise sharply above the surrounding plains. The uplands in the middle part of the Smoky HiMs
region are underlain by limestones and chalky shales. This is the "Fencepost Limestone country",
in which beds of one-foot-thick limestone were used for masonry and for fenceposts on rangeland
(Wilson, 1984). The western part of the Smoky Hills region is developed on thick chalks of the
Cretaceous Niobrara Formation, which form hills and buttes with a badlands appearance. Most of
the western part of the State is in the High Plains region, a subset of the High Plains Province that
begins at the foot of the Rocky Mountains and covers much of the central interior of the United
States from Texas to the Dakotas. The Arkansas River Lowlands (fig. 1) are formed in the broad,
flat valley of the Arkansas River. Much of the valley and surrounding plains are covered by dunes
of windblown sand. Extensive windblown silt deposits, called loess, cover large parts of the
Kansas landscape as well. <
Kansas is divided into 105 counties (fig. 2). The population of Kansas is largely rural,
with farming and livestock as major industries. Most counties have populations less than 10,000
(fig. 3); counties with more than 100,000 inhabitants are those with large urban-centers, including
! Johnson and Wyandotte (Kansas City), Shawnee-(Topeka), and Sedgewick (Wichita) (fig. 3).
GEOLOGY , ,
,, Almost all of the bedrock exposed at the surface in Kansas consists of sedimentary units
ranging in age from Mississippian to Quaternary (fig. 4) (Ross, 1991). 'Igneous rocks native to
Kansas and exposed at the surface are small localized exposures of Cretaceous larnproite in
Woodson County (Wagner, 1954; Cullers and others, 1985) and Cretaceous kimberlite in'Riley
County (Brookins, 1970), Sedimentary rocks of Mississippian age underlie the extreme
southeastern corner of the State (fig. 4). They consist primarily of limestones but also include
shale, dolomite,.chert, sandstone, and siltstone. Pennsylvanian rocks underlie approximately the
eastern one-quarter of the State. They consist of an alternating sequence of marine and nonmarine
shale, limestone, sandstone, and coal, with lesser amounts of chert and conglomerate. The shales
range from green and gray (low organic content) to black (organic rich). Permian rocks are
exposed in east-qentral-and southern Kansas (fig. 4) and consist of limestone, shale, gypsum,
anhydrite, chert, siltstone, and dolomite. Red sandstone and shale (red beds) of Permian age
underlie the Red Hills along the southern border of Kansas (figs. 1,4). Triassic rocks are exposed
at the surface only in a small area in Morton County and consist chiefly of sandstone and shale.
Jurassic rocks are not exposed at the surface in Kansas. Cretaceous sedimentary rocks underlie
much of north-central and central Kansas (fig. 4), and consist of green, gray, and black shale,
sandstone, siltstone, limestone, chalk, and chalky shale. A discontinuous,layer of loess
(windblown silt) of varying thickness covers the Cretaceous rocks in many areas, particularly in
the western part of the Cretaceous outcrop area. Tertiary rocks cover much of western Kansas,
though they are covered by loess deposits in many areas' (fig. 4). Tertiary rocks consist of
IV-3 Reprinted from USGS Open-File.Report 93-292-G
-------
Figure 2. Kansas counties.
-------
POPULATION (1990)
0 0 to 10000
0 10001 to 25000
EH 250011050000
H 50001 to 100000
100001 to 403662 '
Figure 3. Population of counties in Kansas .(1990 U.S. Census data).
-------
ij^:j.|i :|::::::i
|::::} ».*":: :rJsiJr:l Ii»Trr]
S^KiiilisiuiiiiiiiiyJ
;i;«ooosw' ''«««" *" i *w*.,,
; r yigneous;;;:;;: j
H^ilLiil^^h:::::]
Quaternary glacial deposits
Jurassic
Permian
Silurian-Devonian
Cambrian-Ordovician
;«*, Tertiary and Quaternary
Cretaceous
;::f| Pennsylvanian
Mississippian
\'/////, Precambrian
SO
SO 100 mi
i i
100 km
Figure 4. Generalized geologic map of Kansas (modified from Kansas Geological Survey)..
-------
ERAS
GENOZOIC
MESOZOIC
PALEOZOIC
PERIODS EPOCHS
HOLOCENE
PLEISTOCENE
PUOCENE ,
MIOCENE
TERTIARY . OUQOCENE
EOCENE
' ~ .PALEOCEN6
CRETACEOUS
JURASSIC '
TRIASSIC .
". PERMIAN .
PENNSYLVANIAN
MISSISSIPP1AN
DEVONIAN
SILURIAN
ORDOV1CIAN /
CAMBRIAN
F*RECAMBRIAN
EST. LENGTH
IN. YEARS
10,000+
1,990,000
3,000,000
r 19,000,000
14,000,000
17,000,000
8,ooo;ooo
i
- 75,000,000 .
67,000,000
35,000,000
.50,000,000
f
40,000,000
30,000,000
50,000,000 .
25,000,000
65,000,000
70,000,000
1,930,000^000
1,100.000,000 +
TYPE OF ROCK IN KANSAS
Glacial drift; river silt, sand, and
(loess); volcanic ash.
River silt, sand, gravel, fresh-
water limestone; volcanic ash;
bentoriite; diatomaceous marl;
opaline sandstone.
Limestone, chalk, chalky shale,
dark shale, varicolored clay, sand-
stone, conglomerate. Outcropping
igneous rock.
Sandstones and shales, chiefly
subsurface Siltstohe chert'*a*3d
gypsum.
Limestone, shale, evaporites (salt,
gypsum, anhydrite), red sand-
stone; chert, sittstone, dolomite,
and red beds.
Alternating marine and nonmarine
shale, limestone, sandstone, coal;
. chert and conglomerate.
Limestone, shale, dolomite, chert,
oolites, sandstone, and siltstone. "
Subsurface oniy. Limestone, pre-
dominantly black shale; sand-
stone.
Subsurface only. Limestone.
' Subsurface only. Dolomite, sandr. «
stone, , ' ' '
Subsurface only. Dolomite, sand-
stone, limestone, and shale.
Subsurface only. Granite, other
igneous rocks, and metamorphic
rocks, ',
en
in
z.
'O
"Figure"4 (continued) Kansas strati'graphic chart (modified from Kansas Geological Survey).
-------
nonmarine sandstone, siltstone, and shale; volcanic ash deposits; and unconsolidated gravel, sand,
silt, and clay.
Pre-Dlinoian (Pleistocene) glacial drift covers bedrock in the northeastern part of the State
(fig. 4). The glacial deposits consist of a clay, silt, or sand matrix with cobbles and boulders of
igneous and metamorphic rocks derived from as far away as the Lake Superior Region and
southwestern Minnesota (Port, 1987). The glacial deposits are discontinuous and till thickness
varies markedly within the area, most likely because post-glacial erosion has removed and
redistributed significant amounts of drift (Doit, 1987), Loess, windblown silt deposits ranging
from 0 to more than 30 meters in thickness, covers as much as 65 percent of the surface of Kansas
(Welch and Hale, 1987) and is thickest and most extensive in the western and north-central parts of
the State and in proximity to glacial deposits in the northeastern corner of the State (fig. 5).
Possible sources for the loess include: (1) glacial outwash, (2) sand dunes in the Arkansas and
Cimarron River valleys (fig. 4) or elsewhere (such as the Sand Hills of Nebraska), and (3) erosion
by wind and rivers of the Tertiary Ogallala Formation (Welch and Hale, 1987).
Uranium in above-average concentrations (according to Carrnichael (1989), average crustal
abundance of uranium is 2.5 ppm) is found in a number of rocks in Kansas. Uranium is found in
phosphatic black shales of Pennsylvanian age in eastern Kansas. Uranium contents in- the black
shales range from about 15 ppm to 100 ppm; concentrations of as much as 350 ppm uranium are
found in phosphate nodules within the shales (Berendsen and others, 1988). Pennsylvanian
phosphatic black shales exposed in eastern Kansas include the Heebner, Eudora, Muncie Creek,
Quindaro, Stark, Hushpuckney, Anna, LMe Osage, and Excello Shale Members, the Pleasanton
Group, and shales above the Bevier and Croweburg coals (Berendsen and others, 1988; Coveney
and others, 1988). The Cretaceous Sharon Springs Member, a black shale unit at the base of the
Pierre Shale, contains from 10 to 40 ppm uranium in western Kansas (Landis, 1959). Uranium is
associated with silica-cemented layers in the Tertiary Ogallala Formation in several localities in
western Kansas. The uranium content of the rocks appears to correlate directly with the amount of
silica cementation of the rocks, with as much as 125 ppm uranium in the most intensely silicified
layers (Berendsen and Hathaway, 1981; Berendsen and others, 1988). A continuously silicified
area of the Ogallala Formation about 10 miles long and 1.5 miles wide is located in Meade and
Clark Counties (Berendsen and Hathaway, 1981). The source of the uranium and silica in the
Ogallala is postulated to be volcanic ash that is mixed in with the sediments throughout their '
outcrop area (Carey and others, 1952; James, 1977; Zielinski, 1983). Eighteen samples of
volcanic ash from Tertiary and younger rocks in Kansas yielded from 3.9 to 9.1 ppm uranium
(James, 1977). Other uranium occurrences have been found in Mmberlite pipes in Riley County,
in the Cretaceous Dakota Sandstone in Ellsworth County, in the Cretaceous Smoky Hill Member
of the Niobrara Chalk in a large area of Gove County, and in Tertiary volcanic ash outcrops in
Meade and Clark Counties (Zeller and others, 1976).
Anomalous concentrations of uranium in ground water were found in wells producing from
the Permian Nippewalla Group, Cretaceous Kiowa-Cheyenne Sandstones, and' Quaternary
alluvium (Berendsen and others, 1988); anomalous uranium concentrations in ground water (from
2 to 172 parts per billion uranium) have also been noted in wells producing from the Ogallala
aquifer and Arkansas River alluvium in western Kansas (Berendsen and Hathaway, 1981).
Ground water in southeastern Kansas is generally low in uranium but contains elevated
concentrations of 226Ra (Macfarlane, 1981), suggesting that these waters may also contain high
levels of dissolved radon in some areas.
IV-8 Reprinted from USGS Open-File Report 93-292-G
-------
&SBKM&I i?Sv " »!«.» cif ^- N«J '*'< ' *'«*'
.
i-iaLaei Ul j S. _ 3-^. _^
Loess from- Geologic
Mop of Konsds
Old alluvial soils - .
with a loess component
Loess oVerlain by dune sand
Loess mantled areas not
depicted on,Geologic Map
of Kansas
Sedimentary rock, old
and/or recent alluvium,
Or dune sand
0
50
100 mi
0
100 km
Figure 5. Map showing distribution of loess in Kansas (from Welch and Hale, 1987). Loess in the area marked "Loess mantled areas
not shown on Geologic Map of Kansas" is generally less than 2 feet thick;
-------
SOILS
Most soils In Kansas belong to the suborders Ustolls and Udolls (Bidwell and McBee,
1973). If Kansas is vertically divided into quarters, the western quarter of the State is covered by
Aridic Ustolls, the west-central quarter is covered by Typic Ustolls, the east-central quarter is
covered by Udic Ustolls, and the eastern quarter is covered by Typic Udolls. Aridic Ustolls are
deep, grayish-brown silt loams and sandy loams with a layer of calcium carbonate accumulation at
approximately one meter (Bidwell and McBee, 1973), These soils have generally low to moderate,
permeability (fig. 6). The western part of the State that is covered by Aridic Ustolls receives
508 mm (20 in) or less of precipitation annually (Steeples and Buchanan, 1983). Typic Ustolls,
which cover the west-central quarter of Kansas, are deep and moderately deep, dark grayish-
brown to reddish-brown silt loams and clays with calcium carbonate accumulations at 1-2 m depth
(Bidwell and McBee, 1973) and generally low permeability (fig. 6). This part of the State receives
508-635 mm (20-25 in) of precipitation annually. Approximately the east-central quarter of the
State is covered by Udic Udolls, shallow to deep, grayish-brown silt loams and clay loams with
secondary carbonate horizons at more than 1 rn depth (Bidwell and McBee, 1973). These soils
have tew to moderate permeability (fig. 6), and this part of the State receives between 635 mm
(25 in) and 889 mm (35 in) of precipitation annually (Steeples and Buchanan, 1983). Eastern
Kansas receives from 889 mm (35 in) to more than 1000 mm (40 in) of precipitation annually and
is covered by Typic Udolls, black and dark brown silt loams to clay loams with secondary
carbonate accumulations at depths exceeding 1.5 m. These soils have generally low permeability
(fig. 6) and many of the soils in eastern Kansas have seasonally high water tables (Olson, 1974).
Soils developed on alluvium in river valleys, most notably that of the Arkansas River, are sand and.
sandy loams with high permeability (fig. 6). The extreme southeastern corner of Kansas is -
covered by Typic Udults, deep, brown eherty silt loams with secondary calcium carbonate
horizons at more than 1.5 m depth (Bidwell and McBee, 1973) and high permeability (fig. 6).
INDOOR RADON DATA
Screening indoor radon data from 2009 homes sampled in the State/EPA Residential Radon
Survey conducted in Kansas during the winter of 1987-88 are shown in figure 7 and listed in Table
1. Data are only shown in figure 7 for those counties with 5 or more data values. The maximum
value recorded in the survey was 48 pCi/L in Marshall County. Except for counties in the Kansas
City, Topeka, and Wichita areas, most counties in the survey are represented by 20 or fewer
indoor radon measurements (fig. 7); 19 counties have more than 20 measurements. Given the
relatively sparse distribution of data, observations concerning the distribution of indoor radon
concentrations based on these data should not be considered conclusive statements on indoor radon
distributions within Kansas, but they are useful in establishing geologically-related trends.
Most counties in southeastern and south-central Kansas have low (0-2 pQ/L) to moderate
(2-4 pCi/L) indoor radon averages. Counties in northeastern Kansas have moderate to high
(> 4 pC5/L) indoor radon averages (fig. 7). Berendsen and others (1988) report that elevated
indoor radon levels were found in the Kansas City area and in Chanute in a survey of indoor radon
levels by the Kansas Department of Health and Environment Most of the counties in north-central
and central Kansas have high indoor radon averages in the State/EPA survey, and western Kansas
has an approximately equal mixture of counties with moderate and high indoor radon averages
(fig. 7). The highest maximum radon readings occur in northeastern and central Kansas (Table 1).
'lV-10 Reprinted from USGS Open-File Report 93-292-G
-------
SOIL PERMEABILITY
lllLOW(<0.6ln/hr)
VTA MO DERATE (0.6-6.0 irVhr)
r~lHIGH(>6.0liVhrt
* miles
100
Figure 6. Generalized soil permeability map of Kansas (data from Olson, 1974; map'units from Bidwell and McBee, 1973).
-------
Bsmt. & 1st Floor Rn
%>4pCi/L
OtolO
11 to 2.0
21 to 40
41 ta 60
61 to 80
1 I 81 to 100,
12 ' I Missing Data
or < 5 measurements
Bsmt. & 1st Floor Rn
Average Concentration (pCi/L)
0.0 to 1.9
2.0 to 4.0
4.1 to 9.0
Missing Data
or < 5 measurements
Figure 7. Screening indoor radon data from the EPA/State Residential Radon Survey of Kansas,
1987-88, for counties with 5 or more measurements. Data are from 2-7 day charcoal canister
tests. Histograms in map legends show the number of counties in each category. The number of
samples in each county (See Table 1) may not be sufficient to statistically characterize the radon
levels of the counties, but they do suggest general trends. Unequal category intervals were
chosen to provide reference to decision and action levels.
-------
TABLE 1. Screening indoor radon data from the EPA/State Residential Radon Survey of
Kansas conducted during!986-87. Data represent 2-7 day charcoal canister measurements
from the lowest level of each home tested.
COUNTY
ALLEN
ANDERSON
ATCmSON
BARBER
BARTON
BOURBON
BROWN
BUTLER
CHASE
CHAUTAUQUA
CHEROKEE
CHEYENNE
CLARK
CLAY
CLOUD
COEFEY
COMANCHE
COWLEY
CRAWFORD
DECATUR
DICKINSON
DONIPHAN
DOUGLAS
EDWARDS
ELK
ELLIS
ELLSWORTH
FINNEY
FORD
FRANKLIN
GEARY
GOVE
GRAHAM
GRANT
GRAY
GREELEY
GREENWOOD
HAMILTON
HARPER
HARVEY
HASKELL
NO. OF
MEAS.
20
9
10
9
24
15
7
29
10
6
20
11
6
7
11
4
' 5'
29
46
4
15
- 5
36
4
3
26
17
15
14
22
8
8
6
, 8
5
5
5
8
1
13
2
MEAN
0.6
0.8
2.9
1.9
3.4
1.7
2.4
1.6
2.0
0.8
0,9
3.9
4.6
9.0
4.2
2.6
2.0
1.9
1.1
3.1
4.1
3.0
2.6
3.1
0.7
3.6
5.9
2.0
5.4
1.6
6.6
4.4
4.0
4.2
6.2
2.9
1.9
4.7
1.6
3.0
3.4
GEOM.
MEAN
0.3
0.6
2.3
1.6
2.0
1.2
2.1
0.9
1.5
0.5
1 0.5
3.1
3.7
3.7
3.1
1.7
1.0
1.6
0.7
2.4
3.2
2.6
1.6
2.5
0.7
3.2
4.5
1.9
4.2
1.1
5.2
3.7
2.8
3.4
5.8
2.6
1.2
3.4
' 1.4
2.3
3.2
MEDIAN
0.4
0.7
2.3
1.7
1.9
1.3
2.5
1.1
1.3
. 0.4
0.4
2.9
' 4.4
2.4
3.1
2.5
1.0
1.6
0.8
2.4
3.3
3.2
2.0
2.9
0.6
3.6
5.7
1.7
4.3
1.0
5.2
3.7
3.1
3.2
6.4
3.0
1.1
2.8
1.0
2.2
. -3,4
STD.
DEV.
0.6
0.6
2.1
1.0
4.7
1.3
1.2
1.7
1.9
1.0
1.1
3.2
3.0
12.0
3.2
, 1.9
2.9
1.1
1.2
2.4
3.8
1.4
2.5
2.0
0.3
1.8
3.7
0.9
3.8
- 1.5
5.6
2.5
3.2
3.1
2.5
' 1.4
1.9
4.5
1.1
2.5
1.7
MAXIMUM
2.4
2.0
6.9
.3.7
23.0
4.3
4.0
7.6
6.7
2.7
4.0
12.6
9.3
28.1
.9.5
4.9
7.1
4.4
6.0
6.4
16.5
4.5
12.9
5.6
1.0
8.6
13.2
4.7
12.2
5.9
19.3
8.2
9.2
10.1
8.8
4.9
4.9
14.8
3:7
9.9
4.6
%>4pCi/L
0
0
20
"' 0
21
7
0
7
10
0
0
36
"'< . 50
29
36
25
20
7.
. - 4
25
' -V '33
20 ;
. 19
25
0,
38
65
. 7
50
- ' 5
63
50
33
50
80
20
20
38
0
n
50,,
%>20pCi/L
0
0
0
0
4
0
0
0
0
0
0
0
0
29
0
0
0
0
0
0
0
0
0
0
0
0
0
/o
0
0
0
0
0,
0
0
0
0
0
0
0
0
-------
TABLE 1 (continued). Screening indoor radon data for Kansas.
COUNTY
HODGEMAN
JACKSON
JEFFERSON
JEWELL
JOHNSON
KEARNY
K1NQMAN
KIOWA
LABETTE
LANE
LEAVENWORTH
LINCOLN .
LINN
LOGAN
LYON
MARION
MARSHALL
MCPHERSON
MEADE
MIAMI
MITCHELL
MONTGOMERY
MORRIS
MORTON
NEMAHA
NEOSHO
NESS
NORTON
OSAGE
OSBORNE
OTTAWA
PAWNEE
PHILLIPS
POTTAWATOMIE
PRATT
RAWLINS
RENO
REPUBLIC
RICE
RILEY
ROOKS
RUSH
RUSSELL
NO. OF
MEAS.
6
8
10
8
339
9
7
8
17
3
28
7
8
8
17
2
12
21
12
22
8
41
5
8
9
11
19
10
12
9
6
2
27
11
9
10
45
8
7
32
10
8
8
MEAN
3.5
1.1
4.0
3.4
3.8
3.0
1.3
5.2
1.9
2.9
2.5
2.0
1.4
5.3
1.2
3.2
8.5
4.6
4.9
1.8
6.7
0.7
6.3
2.5
3.3
1.3
4.8
4.8
2.5
7,0
3.7
8.9
4.5
3,6
.2.0
2.7
2.2
'2.8
2.5
4.6
3.9
5.1
4.5
GEOM.
MEAN
2.7
1.0
2.7
2.6
*2.5
2.4
0.8
3.7
0.5
1.9
1.6
1.7
0.9
4.7
0.9
3.2
3.7
3.6
3.3
1.4
4.8
0.5
2.3
1.7
2.2
1.0.
3.1
4.2
1.8
5.6
1.5
7.8
. 3.5
1.8
1.9
2.2
1.4
2.2
1.9
2.4
2.9
3.6
3.9
MEDIAN
3.6
1.0
4.3
3.3
2.6
" 3.4
1.2
4.2
0.4
1.6
2.0
.1.2
1.1
6.1
0.7
3.2
3.9
3.7
3.3
1.5
5.4
0.4
2.6
1.4
2.9
0.9
3.8.
4.2
1.6
7.7
1.2
8.9
3.9
1.4
1.7
2.3
1.7
2.8
1.8
2.5
3.8
4.2
3.4
STD.
DEV.
2.1
0.6
2.7
2.4
4.1
1.7
1.2
4.8
4.6
3.1
2.0
1.2
1.1
2.4
1.0
0.1
13.4
3.6
4.3
1.3
5.2
0.7
9.8
2.4
3.0
0.9
5.4
2.4
2.5
4.6
6.4
6.1
2.9
4.9
0.8
1.7
2.2
1.9
2.4
5.6
2.7
4.8
2.7
MAXIMUM
6.7
2.1
7.5
7.4
32.0
5.6
3.0
16.2
19.5
6.4
7.3
3.5
3.1
8.7
3.6
3.3
48.0
17.0
13.4
5.6
16.1
3.5
23.7
7.8
9.8
3.2
24.6
8.6
9.6
16.1
16.6
13.2
13.5
15.3
3.5
5.8
11.7
6.8
7.8
25.5
9.3
15.6
10.0
%>4pCi/L
33
0
60
50
29
33
0
50
6
33
18
0
0
63
0
0
50
43
50
5
63
0
20
13
33
0
47
50
17
67
17
100
48
27
0
20
7
13
14
41
40
50
38
%>20 pCI/L
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
.8
0
0
0.
0
0
20
0
0
0
5
0
0
0
0
0
0
0
0
0
0
0
0
3
0
0
0
-------
TABLE 1 (continued). Screening indoor radon data for Kansas.
COUNTY
SALINE
SCOTT
SEDGWICK
SEWARD
SHAWNEE
SHERIBAN
SHERMAN
SMITH
STAFFORD
STANTON
STEVENS
SUMNER
THOMAS
TREGO
WABAUNSEE
WALLACE
WASHINGTON
WICHITA
WILSON
WOODSON
WYANDOTTE
NO. OF
MEAS.
32
21
217
12
109
8
8
7'
7
4
3
10
14
14
7
3
7
3
15
17
110
MEAN
4.8
5.8
2.1
2.9
2.9
4.6
4.0
4.6
3.8
5.7
13.0
1.5
3.6
3.8
1.9
'4.8
3.4
5.5
1.4
0.7
3.6
GEOM.
MEAN
3.4
4.9
1.6
2.6
1.9
3.3
3.2
4.1
3.0
5.0
6.4
1.1
3.0
3.1
1.7
4.8
,2.4
^ 5.4
0.8
0.5
2.5
MEDIAN
3.5
5.4
1.6
2.7
' , 2.1
3.0
2.8
4.4
3.7
6.5
9.1
1.7
3.0
3.1
1.7
4.7
2.7
-5.0
0.5
0.5
3.1
STD.
DEV.
4.5
3.2
1.7
1.2
3.1
4.0
2.9
2.2
2.4
2.8
14.4
1.0
2.3
2.5
1.0
0.4
2.4
1.1
2.1
0.6
3.1
MAXIMtFM
20.7
15.7
8.0
5.6
19.7
12.2
9.3
7.5
7.0
7,9
29.0
3.2
9.9
9.1
3.4
5.2
7,0
6.8
7:7
2.1
16.3
%>4 pCi/L
38
81
12
8
22
38
*!*»38
57
43
75
67
0
36
.... 43
0
-" 100
43
100
7
0
35
%>20 pCi/L
i 3
0
0
-Q
0
0
0
0
0
0
33
0
0
0
0
0
0
0
,0
0
0
-------
GEOLOGIC RADQN POTENTIAL
An examination of geologic (fig, 4), soil (fig. 6), indoor radon (fig. 7), and radioactivity
(fig. 8) data allows identification of rocks and sediments in Kansas that have the potential to
generate indoor radon levels exceeding the EPA's 4 pCi/L guideline. A northeast-southwest
trending line of high radioactivity (for this evaluation, "high" is defined as greater than 2.5 ppm
equivalent uranium [eU]) in southeastern Kansas (fig. 8) is likely associated with Pennsylvanian
black shales. However, most of the Pennsylvanian black shale outcrops are thin, usually no more
than a few meters thick, so they are too narrow to detect on the aerial radioactivity map, which has .
a grid cell, or "pixel", size of about 2.5 km (1.6 mi) (Duval and others, 1989). Permian
sedimentary rocks comprising the Chautauqua Hills (fig. 1) have a low (<1.5 ppm eU)
radioactivity signature (fig. 8). With these exceptions, Pennsylvanian and Permian rocks in the
State have an overall intermediate (1.0-2.5 ppm eU) radioactivity signature. Because the majority
of Pennsylvanian and Permian rocks have relatively low uranium contents, and because soils
developed on these rocks have generally low permeability and many are subject to seasonally high
water tables, these rocks have a generally low radon potential. However, homes situated on
Pennsylvanian and Permian carbonate rocks (limestones and dolomites) may have locally elevated
indoor radon levels if the limestones have developed clayey residual soils and(or) if solution
features (karst topography), are present in the area. Although the carbonate rocks themselves are
generally low in uranium and radium, the soils developed on these rocks are typically derived from
the residual materials of dissolution of the CaCOs that makes up the majority of the rock. When
the CaCOs has been dissolved away, the soils are enriched in the remaining impurities,
predominantly base metals, including uranium. Carbonates also form karst topography,
characterized by solution cavities, sinkholes, and caves, which increase the overall permeability of.
the rocks in these areas and may induce or enhance convective flow of radon. Homes sited on
Pennsylvanian black shale units are likely subject to locally high indoor radon levels. This appears
to be the case in the Kansas City area, part of which is underlain by black shales (fig. 7> Berendsen
and others, 1988).
Some elevated indoor radon levels in the northern part of the Permian outcrop area,
specifically in Marshall, Clay, Riley, Geary, and Dickinson Counties, may be related to faults and
fractures of the Mid-Continent Rift and Nemaha Uplift (Berendsen and others, 1988). The Mid-
Continent Rift (MCR) zone is an area of NNE-SSW-trending faults and fractures which were most
active during Late Mississippian to Early Pennsylvanian time (Berendsen and others, 1989), but
have been active during modern times, as evidenced by modern microearthquakes (Wilson, 1979).
Many of the subsurface faults reach and displace the surface sedimentary rock cover, and the
density and spacing of faults and fractures within the rift zone is relatively high (Berendsen and
Blair, 1986; Berendsen and others, 1989). Soil-gas helium surveys conducted jointly by the
Kansas Geological Survey and the U.S. Geological Survey indicate that faults and fractures within
the MCR are areas of high permeability and they show evidence that fluids and gases are able to
migrate upward from deeper source rocks (G.M. Reimer, unpublished report, 1985). Fault and
shear zones are commonly areas of locally elevated radon because these zones typically have higher
permeability than the surrounding rocks, because they are preferred zones of uranium
mineralization, and because they are pathways for potentially uranium-, radium-, and(or) radon-.
bearing fluids and gases to migrate (Gundersen, 1991).
IV-16 Reprinted from USGS Open-File Report 93-292-G
-------
0^ °f ^fsan iafter D^?! md others' 1989>- Contour Hnes at L5 ^ 2.5 ppm equivalent uranium (ell).
Pixels shaded from 0 to 6.0 ppm eU at 0.5 ppm eU increments; darker pixels have lower eU values; white indicates no data.
-------
Cretaceous rocks in northern, central, northwestern, and west-central Kansas include
sandstones, shales, and local volcanic ash deposits that contain sufficient uranium to generate
elevated indoor radon levels. The Cretaceous rocks overall have a moderate (1.5-2.5 ppm elJ)
radioactivity signature (fig. 8). Some areas of higher radioactivity may be masked by surface
accumulations of loess, A few scattered radioactivity anomalies in western and central Kansas
(fig. 8) may be associated with outcrops of the Sharon Springs Member of the Pierre Shale or with
alluvium in major drainages. Soils developed on Cretaceous rocks have low to moderate
permeability (fig. 6), but the shale-derived soils with low permeability to water likely have
moderate permeability to soil gas when they are dry due to desiccation cracks (Schumann and
others, 1989,1991). Areas underlain by these rocks have an overall high radon potential. Areas
underlain by the Tertiary Ogallala Formation have a moderate radioactivity signature and a
moderate to high radon potential. Again, the radioactivity of the bedrock may be masked in some
areas by surflcial loess deposits. .
Although loess in many cases has lower radioactivity than underlying bedrock units, it
typically is able to generate as much or more radon than the bedrock it covers. Radon potential of
loess-mantled areas depends on the thickness and source of the loess. In areas of very thin loess
cover, the radon potential of the underlying bedrock is significant, and the loess both generates
radon and transmits radon from the underlying bedrock, whereas if the loess is more than 7-10 m
thick, it is probably the sole radon source for homes in the area. Because several sources are
postulated for loess in Kansas, and loess thickness in the State has not yet been mapped in detail
(Welch and Hale, 1987), it is difficult to make definitive statements concerning the radon potential
of loess-mantled areas in Kansas. However, similar loess deposits in southern Nebraska generate
widespread elevated indoor radon levels (see the Nebraska radon potential chapter in this volume).
Loess-covered areas underlain by Cretaceous and Tertiary bedrock appear to have variably
moderate to high radon potential across the State, and locally elevated indoor radon levels may be
expected anywhere within areas underlain by these units. Areas underlain by loess-covered
Pennsylvanian and Permian rocks appear to generate moderate to locally elevated indoor radon
levels.
The area within the glacial limit in northeastern Kansas is underlain by discontinuous
glacial drift and loess. Because the loess in this area is likely derived from nearby glacial drift, and
because glacial deposits are known to generate elevated indoor radon levels throughout the
northern Great Plains, this area should be considered to have a moderate to locally high radon
potential. Areas of windblown sand in the Arkansas and Cimarron River valleys have a low
radiometric signature (fig. 8). The sand dunes themselves have low uranium contents and low
radon potential, but few homes are built directly on the sand dunes. The dune sands are intermixed
with loess in parts of the'Arkansas and Cimarron valleys, and the radon potential may be related to
the relative proportions of sand, loess, and bedrock within these areas. Areas underlain by dune
sand are expected to have lower radon levels, areas with considerable loess content are expected to
have moderate to locally elevated radon levels. Where sand or loess is thin or absent, the radon
levels in homes on Tertiary or Cretaceous bedrock are also expected to generally fall into the
moderate to high category.
IV-18 Reprinted from USGS Open-File Report 93-292-G
-------
SUMMARY'; ." . '_ ' ' . -" -: . v ' ,
For the purposes of this assessment, Kansas is divided into six geologic radon potential ,
areas (fig. 9) and each areff assigned Radon Index (RI) and Confidence Index (CI) scores
(Table 2). The Radon Index is a semiquantitative measure of radon potential based on geologic,
soil, and indoor radon factors, and the Confidence Index is a measure of the relative confidence of
the RI assessment based on the quality and quantity of data used to make the predictions (see ,the
Introduction chapter for more information on the methods and data used). At the scale of this
report the outlines of the areas shown oh figure 9 are generalized, and the descriptions given in this
text should be compared with more detailed geologic and other maps. '
Area PPR is.underlain by Pennsylvanian and Permian rocks. Homes in this area may have
indoor radon levels ranging from low (<2 pCi/L) to high (>4 pCi/L}, depending on the local
underlying geology and presence and thickness of loess cover. Additional indoor radon data
compiled by the Kansas Department of Health and Environment (written communication, 1992)
suggest that more homes in this area have moderate to high indoor radon levels than are indicated
by the State/EPA Residential Radon Survey data, so the indoor radon factor was assigned 2 points,
but because the data are partially from a non-randomly-sampled volunteer source, the factor is
given 2, rather than 3, confidence index points. Homes built on uranium-bearing Pennsylvanian
black shales within this area may have locally high indoor radon levels. Some areas underlain by
carbonate rocks (limestones and dolomites) may have locally elevated indoor radon levels,
especially if solution features or clay-rich residual soils have developed (the residual soils are
commonly red or orange-red in color due to concentration of iron .oxides in the residuum). Some
domestic wells drawing water from lower Paleozoic aquifers in this area may contribute to elevated
'radon levels by release of dissolved radon from the water into the indoor air. Area PPR is
assigned a moderate or variable overall radon potential (RI=9) with moderate confidence (CI=9).
Area GLA is underlain by glacial drift and loess of varying thickness. Although the
bedrock source for the glacial drift can be traced as far as the Canadian Shield, a large proportion
of the drift is relatively locally derived from underlying and nearby Paleozoic sedimentary rocks
that are relatively poor radon sources. Higher permeability of the drift relative to bedrock, the
presence of crystalline glacial erratics, and the variability of loess cover and source (primarily
glacially derived) cause this area to have moderate to high radon potential, and it is assigned.an
overall high geologic radon potential (RI=12), with a high confidence index (CI=10).
Area MCR is an area of faults and fractures related to the Mid-Continent Rift zone. Homes
sited on unfaulted Permian bedrock in this area are likely to have low radon levels, but those sited
on surface or near-surface faults or fractures may have locally high indoor radon levels. The
boundaries of the area aYe drawn along major subsurface faults that delineate the rift system ,
(Berendsen and others, 1989). Overall, area MCR is assigned a high radon potential (RI=12) with
high confidence (CI=10). .
Area KR delineates the bedrock outcrop pattern of Cretaceous sedimentary rocks in
Kansas. Parts of this area, particularly the western part, are covered by discontinuous loess
deposits. Gray and black shale units of the Pierre Shale typically generate moderate to high indoor
radon levels. The Dakota and Niobrara Formations and the Pierre Shale are known to contain
locally anomalous amounts of uranium and are known producers of elevated radon in some areas.
Overall, area KR has a higkradon potential (RI=12) with high confidence (CI=11)..
Area TL is mostly underlain by Tertiary rocks, specifically the Ogallala Formation, that are
mostly covered by younger loess.deposits. The highest radon levels in this area are expected" to
IV-19.. Reprinted from USGS Open-File Report 93-292-G
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occur In homes sited on siliceous (silica-cemented) Ogallala Formation, particularly in the
southwestern part of the State. Radon levels in structures built on loess deposits are expected to
range from moderate to high depending on the thickness and mineralogy of the loess. Because the
indoor radon data indicate that many areas underlain by loess or Tertiary sedimentary rocks have
county average indoor radon levels exceeding 4.0 pCi/L, and because many of the counties in
western Kansas have relatively few sampled homes in the State/EPA survey, a conservative
approach to ranking the area was adopted. Indoor radon levels in this area are expected to range
from low (< 2 pCi/L) to high (> 4 pCi/L) but are most likely to be in the moderate to high range,
so area TL is assigned an overall high radon potential (RI=12) with high confidence (CI=11).
DS denotes areas underlain by dune sands in the Arkansas and Cimarron River valleys.
The dune sands are highly permeable, but because they are composed almost entirely of quartz
grains containing little or no uranium or radium, they generally generate low radon levels. If the
deposits are thin (less than approximately 15 ft thick), the sands are likely to transmit radon from
the underlying bedrock toward the surface and into homes built on these deposits. Relatively
higher indoor radon levels are also more likely to occur where the sands are mixed with loess
deposits. Area DS is assigned a moderate or variable geologic radon potential (RI=10), with a
high confidence index (CI=11).
This is a generalized assessment of the State's geologic radon potential and there is no
substitute for having a home tested. The conclusions about radon potential presented in this report
cannot be applied to individual homes or building sites. Indoor radon levels, both high and low,
can be quite localized, and within any radon potential area there will likely be areas with higher or
lower radon potential that assigned to the area as a whole. Any local decisions about radon should
DM be made without consulting all available, local data. For additional information on radon and
how to test, contact your State radon program or EPA regional office. More detailed information.
on state or local geology may be obtained from the State geological survey. Addresses and phone
numbers for these agencies are listed in chapter 1 of this booklet.
IV-20 Reprinted from USGS Open-File Report 93-292-G
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TABLE 2. Radon Index (RI) and Confidence Index (CI) scores for geologic radon potential areas
of Kansas. See figure 9 for locations of areas.
-, . - " ' 'AREA; ' ' ;
PPR
FACTOR
1ND(X)R RADON
RADIOACHVTTY
GEOLOGY
SOIL PERM.
ARCHITECTURE
GEE POINTS
TOTAL
. RANKING
RI
2
2'
2 '
- ,1 ,
2
' 0
9
MOD
CI
2
3
2
2
-,
1 -._
9
MOD
KR
FACTOR
INDOOR RADON
RADIOACTIVITY
GEOLOGY
. SOIL PERM.
. ARCHITECTURE
GFE POINTS
TOTAL
RI
2
...2
'3
"2
,3 .
0
12
CI
3
3 .
3
2 -
- ' "
' ". ' " .
11
GLA
RI
2
.' '2- .
3'
' 2 '
3
0
' 12
HIGH'
CI
3' '
2
- 3
2 . '
_
, '_ .'
10 -
HIGH
TL
RI
, 2
.-2V
. 3. '
' 2
3
0
- 12 '
CI
3 '
3 .
'3
-...-I
_
_
11
. MCR
RI
3 ..
2
3
' 1
'- 3 :
0
' 12= '
' - -HIGH ''
DS
RI
. ' 2
1
1 2
" . 2
3
0
10
CI
3 .'
3
2
2
' -
_
10
HIGH
CI
.3 ,
3
3
2
- .
_
11
RANKING 'HIGH HIGH
HIGH ' HIGH
MOD. HIGH
RADON INDEX SCORING:
Probable screening indoor
Radon potential category
LOW
MODERATE/VARIABLE
HIGH
Point range
3-8 points
9-11 points
> 11 points , "
radon average for area
<2pCi/L
2~4pCi/L
>4pQ/L
Possible range of points = 3 _to 17
CONFIDENCE INDEX SCORING:
LOW CONFIDENCE
MODERATE CONFIDENCE
HIGH CONFIDENCE
4-6 points
7-9 points
10-12 points
Possible range of points = 4 to 12
IV-21 Reprinted from USGS Open-File-Report 93-292-G
-------
RADON POTENTIAL:
MODERATE
HIGH
Figure 9. Geologic radon potential areas of Kansas. See Table 2 and text for descriptions and rankings of areas.
-------
REFERENCES USED IN THIS REPORT
AND GENERAL REFERENCES PERTAIMNG TO RADON IN KANSAS
Bainum, D., Barton, J., Miller, D., To, D. and Trupp, R., 1989, Radon concentration in houses
in the vicinity of Topeka, Kansas: Transactions of the Kansas Academy of Science, v. 92,
p. 63-69. ' . : ";. , s ' , ''; . . 'A , ' :';
Berendsen, P., and Hathaway, L.R., 1981, Uranium in unconsolidated aquifers of western
Kansas: Kansas Geological Survey Mineral Resource Series 9,43 p.
Berendsen, P., and Blair, K.P.; 1986, Subsurface structural maps over the Central North
American rift system (CNARS), central Kansas, with discussion: Kansa§*Geologieal
Survey Subsurface Geology Series 8,16 p., 7 plates.
. " s ' , - \
" % -
Berendsen, P., Hathaway, L.R. and Macfarlane, P.A., 1988, Radionuclide distributions in the
natural environment in Kansasa review of existing data, in M.A. Marikos and R.H.
Hansman (eds), Geologic causes of natural radionuclide anomalies: Proceedings of
GEORAD conference, St. Louis, MO, Apr. 21-22,1987, Missouri Department of Natural -
Resources Special Publication 4, p. 65-74. *>.-
t ' ' ' "*"
Berendsen, P., Newell, K.D., and Blair, K.P., 1989, Structural aspects of the mid-content rift
system in Kansas: American Association of Petroleum Geologists Bulletin, .v. -73, p.
1043. , . . r
Bidwell, O.W., and McBee, C.W., compilers, 1973, Soils of Kansas: Kansas Agricultural.
Experiment Station, Department of Agronomy Contribution No, 1359, scale 1:1,125,000,.
f -
Brookins, D.G., 1970, The Mmberlites of Riley County, Kansas: Kansas Geological Survey
Bulletin 200, p. 3-32. , '
Carey, S.J., Frye, J.C., Plummer, N., and Swineford, A., 1952, Kansas volcanic-asri'resources:
Kansas Geological Survey Bulletin 96, 68 p.
' ** i ' '
Carmichael, R.S., 1989, Practical Handbook of physical properties of rocks and minerals: Boca
Raton, Ela., CRC Press, 741 p.- . ,- " .
Coveney, R.M., Jr., Hilpman, P.L., Allen, A.V., and Glascockj M.D., 1988, Radionuclides in
Pennsylvanian black shales of the midwestern United States, in M.A. Marikos and R.H.
Hansman (eds), Geologic causes of natural radionuclide anomalies: Proceedings of
GEORAD conference, St Louis, MO, Apr. 2i-22,1987, Missouri Department of Natural
Resources Special Publication 4, p. 25-42.
, Cullers, R.L., Ramakrishnan, S., Berendesn, P., and Griffin, T., 1985, Geochemistry and
petrogeriesis of lamproites, Late Cretaceous age, Woodson County, Kansas, US A:'
Geochimica et Cosmochimica Acta, v. 49, p. 1383-1402.
TV-23 Reprinted-firom US!3S Open-File Report 93-292-G
-------
Dort, Wakefield, Jr., 1987, Salient aspects of the terminal zone of continental glaciation in Kansas,
in Johnson, W.C., ed., Quaternary environments of Kansas: Kansas Geological Survey
Guidebook Series no. 5, p. 55-66.
Duval, J.S., Jones, W.J., Riggle, F.R., and Pitkin, J.A., 1989, Equivalent uranium map of the
conterminous United States: U.S. Geological Survey Open-File Report 89-478,10 p.
Gundersen, L.C.S., 1991, Radon in sheared metamorphic and igneous rocks, in Gundersen,
L.C.S., and Wanty, R.B. (eds), Field studies of radon in rocks, soils, and water: U.S.
Geological Survey Bulletin 1971, p. 39-50. . ,
James, G.W., 1977, Uranium and thorium in volcanic ash deposits of Kansas: Implications for
uranium exploration in the Central Great Plains, in Waldron, G.A.; ed, Short Papers on
Research in 1977: Kansas Geological Survey Bulletin 211, part 4, p. 1-3.
Landis, E.R., 1959, Radioactivity and uranium content, Sharon Springs Member of the Pierre
Shale, Kansas and Colorado: U.S. Geological Survey Bulletin 1046-L, p. 299-319.
Macfarlane, P.A., 1981, Distribution of radium-226 in the lower Paleozoic aquifers of southeast
Kansas and adjacent areas, in Hemphill, D.D., (ed), Trace substances in environmental
health XIY, a symposium: Columbia, Missouri, University of Missouri, p. 78-85.
Olson, J.W., 1974, Using soils,of Kansas for waste disposal: Kansas Geological Survey Bulletin
208,51 p. . :
Ross, Jorgina A., compiler, 1991, Geologic map of Kansas: Kansas Geological Survey, scale
1:500,000.
Schumann, R.R., Owen, D.E., and Asher-Bolinder, S., 1989, Weather factors affecting soil-gas
radon concentrations at a single site in the semiarid western U.S., in Osborne, M.C., and
Harrison, J., Symposium Cochairmen., Proceedings of the 1988 EPA Symposium on
Radon and Radon Reduction Technology, v. 2, EPA Publication EPA/600/9-89/006B,
p. 3-1 to 3-13.
Schumann, R.R., Peake, R.T., Schmidt, K.M., and Owen, D.E., 1991, Correlations of soil-gas
and indoor radon with geology in glacially derived soils of the northern Great Plains, in
Proceedings of thfe 1990 International Symposium on Radon and Radon Reduction
Technology, Volume 2, Symposium Oral Papers: U.S. Environmental Protection Agency
report EPA/600/9-9l/026b, p. 6-23-6-36:
Steeples, D.W., and Buchanan, Rex, 1983, Kansas geomaps: Kansas Geological Survey
Educational Series 4,30 p.
Wagner, H.C., 1954, Geology of the Fredonia quadrangle, Kansas: U.S. Geological Survey Map ,
GO-49. .
IV-24 Reprinted from USGS Open-File Report 93-292-G
-------
Welch, I.E., and Hale, J.M., 1987, Pleistocene loess in Kansasstatus, present problems, and
future considerations, in Johnson, W.C., ed., Quaternary environments of Kansas:
Kansas Geological Survey Guidebook Series no. 5, p. 67-84. ,
Wilson, Frank, 1984, Landscapes: A geologic diary, in Buchanan, Rex, ed,, Kansas geology:
Lawrence, Kansas, University of Kansas Press, p. 9-39.
Wilson, F.W., 1979, A study of the regional tectonics and seismicity of eastern Kansas
. summary of project activities and results to the end of the second year, or September 30,
1978: U.S. Nuclear Regulatory Commission report NUREG/CR-0666, 68 p.
Zeller, E.J.; Dreschhoff, G,, Angino, E., Holdoway, K., Hakes, W., Jayaprakssh, G., Crisler,
K,, and Saunders, D.F., 1976, Potential uranium host rocks and structures in the central
Great Plains: Kansas Geological Survey Geology Series 2,59 p.
ZielinsM, R.A., 1983, Tuffaceous sediments as source rocks for uraniumA case study of the
White River Formationj Wyoming: Journal of Geochemical Exploration, v. 18,
. p. 285-306.
'. . ' " / v
IV-25- Reprinted from USGS.Opeft-Fiie Report 93-292-G
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Page Intentionally Blank
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EPA's Map of Radon Zones
The USGS' Geologic Radon Province Map is the technical foundation for EPA's Map
of Radon Zones. The Geologic Radon Province Map defines the radon potential for
approximately 360 geologic provinces. EPA has adapted this information to fit a county
boundary map in order to produce the Map,of Radon Zones. .
The Map of Radon Zones is based on the same range of predicted screening levels of
indoor radon as USGS' Geologic Radon Province Map. EPA .defines the three zones as
follows: Zone One areas have an average predicted indoor radon screening potential greater
than 4 pCi/L. Zone Two areas are predicted to have an average indoor _radon-«&creening
potential between 2 pGi/L mnd 4 pCi/L. Zone Three areas are predicted to have an average
indoor radon screening potential less than 2 pCi/L.
Since the geologic province boundaries cross state and county boundaries, a strict
translation of counties from the Geologic Radon Province Map to the Map of Radon Zones
was not possible. * For counties that have variable radon potential (i.e.j are located in two or
more provinces of different rankings), the counties were assigned to "a zone based on the
predicted radon potential of the province in which most, of its area lies. (SeevPart I for more
details.) -_ : ' .;' .-.'
KANSAS MAP OF RADON ZONES . '. , . ...... .. - ' '
The Kansas'Map of Radon Zones and its supporting documentation (Part IV of this
report) have received extensive review by Kansas geologists and radon program experts. The
map for Kansas generally reflects current State knowledge about radon for its counties. Some
States have been able to conduct radon investigations in 'areas smaller than geologic provinces
and counties, so it is important to consult locally available, data. .>,.;,.** .. "
Two county designations do not strictly follow the methodology for adapting the
geologic provinces to county boundaries. EPAj and the Kansas Department of Health and the
Environment have decided to designate Douglas and Marion counties as Zone 1. Although
these areas are rated as having a moderate radon potential on the whole, areas of variability
and high radon potential are known to. exist in these counties. Supplemental indoor radon
data that was submitted by the Kansas Department of Heal-th and the Environment indicate
that these counties have significant percentages of homes above 4 pCi/L and therefore warrant
Zone 1 designations. ,
Althougrrthe information provided in Part IV of this report -- the State chapter entitled
"Preliminary Geologic Radon Potential Assessment-.of Kansas" may appear to be quite
specific, it cannot be applied to determine the radon levels of a neighborhood, housing tract,.
individual house, etc.' THE .ONLY WAY, TO DETERMINE IF A'HOUSE'HAS ' :
ELEVATED INDOOR RADON IS TO TEST. Contact the Region 7 EPA office' or the"
Kansas program for information on testing and fixing homes. Telephone numbers and
addresses pan be found in Part II of this report "
V-l
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KANSAS - EPA Map of Radon Zones
Th« purpow of ftfe map h to assist NatonaJ, StoJt emd tecal orjjanbatJorw
to target ttwfr resources end to Imptoment rodwMesJstant building codas.
This map Is not Intended to determine if a home in a given zone should be tested
for radon. Homes with elevated levels of radon have been found in all three
zones. AH homos should bo tested, regardless of zono designation.
DONIPHAN
Zone 1
Zone 2
Zone 3
IMPORTANT: Consult the publication entitled "Preliminary Geologic Radon
Potential Assessment of Kansas* before using this map. This
document contains information on radon potenial variations wittiin counties.
EPA also recommends that this map be supplemented with any available
local data in order to further understand and predict the radon potential of a
specific area.
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