EPA-600 /R-96-108
September 1996
Site Specific Measurements of
Residential Radon Protection Category
Final Report
by
Kirk K.. Nielson, Rodger B. Holt, and Vern C. Rogers
Rogers & Associates Engineering Corporation
P.O. Box 330
Salt Lake City, UT 84110-0330
EPA Interagency Agreement RWFL 933783
DC A Agreement 95RD-30-13-00-22-001
EPA Project Officer; David C. Sanchez
National Risk Management Research Laboratory
Research Triangle Park, NC 27711
DCA Project Officer: Mohammad Madani
Florida Department of Community Affairs
2740 Centervicw Drive
Tallahassee, FL 32399
University of Florida Project Directors: John F. Alexander and Paul D. Zwick
Department of Urban and Regional Planning
431 ARCH, University of Florida
Gainesville, FL 32611
Prepared for:
State of Florida
Florida Department of Community Affairs
2740 Centcrview Drive
Tallahassee. FL 32399
and
U. S. Environmental Protection Agency
Office of Research and Development
Washington, DC 20460
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4. TITLE AND SUBTITLE
Site-specific Measurements of Residential Radon
Protection Category
TECHNICAL REPORT DATA
(Please read Intxmctions on the reverse before comp,
1. REPORT NO.
EPA-600/R-96-108
2.
5. REPORT DATE
September 1896
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
KirkK. Nielson, Rodger B. Holt, and Vern C. Rogers
8. PERFORMING ORGANIZATION REPORT NO.
RAE-9226/7-1R2
9. PERFORMING ORGANIZATION NAME AND AODRESS
Rogers and Associates Engineering Corporation
P. O. Box 330
Salt Lake City, Utah 84110-0330
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
RWFL933783 (EPA I AG)
95RD-30-13-00-22-001 (DCA)
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final; 7/94-6/95
14. SPONSORING AGENCY CODE
EPA/600/13
15. supplementary notes ^ppc£) project officer is David C.
541-2979.
Sanchez, Mail Drop 54, 919/
is. abstract jj.ie rep0r(; describes a series of benchmark measurements of soil radon
potential at seven Florida sites and compares the measurements with regional esti-
mates of radon potential from the Florida radon protection map. The measurements
and map were developed under the Florida Radon Research Program to identify the
amount of radon resistance that is needed for new buildings in different parts of Flo-
rida. While the measurement protocol and the radon map have a common theoretical
basis, the tests were designed to represent small site areas (4,000 sq m), compared
with the larger 4 million sq m regions typically shown on the radon protection map.
The comparisons included two sites mapped in the low radon potential category, thre?
in the intermediate category, and two in the elevated category. Twenty samples were
collected at each site from five boreholes to depths of 2.4 m. Measurements included
soil radium concentration, density, texture classification, radon concentration, and
water table. A simplified alternative protocol for estimating soil radium distributions
from gamma-ray logs of the five boreholes was also examined. The field measure-
ments were analyzed with the RAETRAD-F computer code. The analyses showed that
both of the sites mapped in the elevated radon potential category had elevated radon
potentials and that both sites mapped in the low category had low radon potentials.
17.
KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. cos ATI Field/Group
Pollution
Radon
Soils
Emission
Measurement
Residential Buildings
Pollution Control
Stationary Sources
13 B
07b
08G.08M
14G
13 M
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
58
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220 ) (9-73)
A-8
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FOREWORD
The U.S. Environmental Protection Agency is charged by Congress with pro-
tecting the Nation's land, air, and water resources. Under a mandate of national
environmental laws, the Agency strives to formulate and implement actions lead-
ing to a compatible balance between human activities and the ability of natural
systems to support and nurture life. To meet this mandate, EPA's research
program is providing data and technical support for solving environmental pro-
blems today and building a science knowledge base necessary to manage our eco-
logical resources wisely, understand how pollutants affect our health, and pre-
vent or reduce environmental risks in the future.
The National Risk Management Research Laboratory is the Agency's center for
investigation of technological and management approaches for reducing risks
from threats to human health and the environment. The focus of the Laboratory's
research program is on methods for the prevention and control of pollution to air,
land, water, and subsurface resources; protection of water quality in public water
systems; remediation of contaminated sites and groundwater; and prevention and
control of indoor air pollution. The goal of this research effort is to catalyze
development and implementation of innovative, cost-effective environmental
technologies; develop scientific and engineering information needed by EPA to
support regulatory and policy decisions; and provide technical support and infor-
mation transfer to ensure effective implementation of environmental regulations
and strategies.
This publication has been produced as part of the Laboratory's strategic long-
term research plan. It is published and made available by EPA's Office of Re-
search and Development to assist the user community and to link researchers
with their clients.
E. Timothy Oppelt, Director
National Risk Management Research Laboratory
EPA REVIEW NOTICE
This report has been peer and administratively reviewed by the U.S. Environmental
Protection Agency, and approved for publication. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Information
Service, Springfield, Virginia 22161.
i a
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ABSTRACT
The Florida Radon Research Program has developed standards for radon-resistant
building construction, and has also developed state-wide maps and site testing protocols to
identify the amount of radon resistance that is needed for particular regions or sites. This
report examines the consistency of the site radon testing protocols with regional estimates
from the Florida radon protection map. The protocols for site-specific tests were designed to
represent areas of one acre (4xl03 m2) or less, compared with the 8,800-acre (3.6xl07 m2)
regions typically shown on the radon protection map. The protocols were based on model
calculations identical to those used to develop the map. However, there have been no
previous comparisons of site-specific radon potential measurements with the categories shown
on the radon protection map. This report documents a series of benchmark measurements
of soil radon potential at sites located in areas that are designated by the map as having low,
intermediate, and elevated radon potentials. This report also documents a simplified
alternative approach for measuring soil radium distributions.
The protocol for the site specific measurements included collection of 20 soil samples
from 5 boreholes, and measurement of their radium concentration by laboratory assay. The
soil density, texture classification, radon concentration, and water table were also measured
at each site. Seven sites were selected for the benchmark comparisons. Two were in areas
mapped with a low radon potential category, three were in areas mapped with an
intermediate radon potential category, and two were in areas mapped with an elevated radon
potential category. The latitude and longitude of each site were measured with a global
positioning system to positively associate the site with a polygon of the radon protection map.
The simplified alternative protocol for soil radium measurement involved gamma-ray
logging of each of the five boreholes used for soil characterization. Although this simpler
method gives faster results at lower cost, it is potentially less accurate because of the added
uncertainty in calibrating gamma ray intensity to soil radium concentration. The potential
errors are generally conservative, however, because radium variations are considered in
interpreting the results and also because thorium-chain gamma rays increase the total
radium estimate but not the radon source strength.
ii
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Soil radium concentrations ranged from 0.2 pCi g"1 to 20.8 pCi g'1, and soil water
contents ranged from 3.2% to 61.3% (dry mass basis). Soil textures were mostly sand, but
about 30% were sandy loam, loamy sand, and finer-textured classifications. Soil densities
ranged from 1.41 g cm'3 to 1.68 g cm"3, and soil radon concentrations ranged from 91 to 4,130
pCi L"1. Quality assurance analyses of 10% duplicates, blanks, and standards demonstrated
adequate precision and accuracy control for the soil radium assays.
Analyses of the field measurements with the RAETRAD-F computer code and the
laboratory radium assays demonstrated that both of the sites mapped in the elevated radon
potential category had elevated radon potentials, and that both of the sites mapped in the low
category had low radon potentials. Two of the three sites mapped in the intermediate
category had intermediate radon potentials, while the third site mapped as intermediate had
a low radon potential, but was near the interface of the low and intermediate categories.
Although there was a significant probability of finding individual sites in any map region
with differing radon potential categories, the sites selected for this study generally showed
excellent correspondence between the mapped and measured categories.
Analyses of the field data with the RAETRAD-F computer code and the alternative
borehole gamma-ray estimates of radium concentration gave similar results. Both of the sites
mapped in the elevated radon potential category had elevated radon potentials, and both of
the sites mapped in the low category had low radon potentials. The intermediate-mapped
site that measured low was again found to be low, but the other two intermediate-mapped
sites were conservatively modeled to have elevated radon potential. The conservatism was
attributed to use of total radium (including 232Th-chain contributions) from the borehole
measurements in the analyses, and possibly also to vertical mixing during soil boring.
A more generalized comparison between statewide RAETRAD-F calculations and the
radon protection map also showed consistency. This comparison was complicated by an
inherent difference in scale between regional variations (for areas averaging 8,800 acres) and
localized variations (for sites of 1 acre or less). Nevertheless, the comparison suggested that
even the complete state-wide distribution of radon potentials is consistent with the trends
shown by the RAETRAD-F model.
iii
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Chapter
TABLE OF CONTENTS
Page No.
Abstract ii
List of Figures v
List of Tables vi
1. INTRODUCTION 1-1
1.1 Background 1-1
1.2 Objective and Scope 1-2
2. SITE-SPECIFIC MEASUREMENTS 2-1
2.1 Test Protocol 2-1
2.1.1 Site Sampling and Measurements 2-1
2.1.2 Soil 226Ra Concentration 2-2
2.1.3 Soil Density 2-3
2.1.4 Soil Textural Classification 2-3
2.1.5 Soil 222Rn Concentration 2-4
2.1.6 Water Table Depth 2-5
2.1.7 Analysis of Site-Specific Measurements 2-5
2.2 Site Selection 2-6
2.3 Field Procedures 2-10
2.3.1 Location 2-10
2.3.2 Soil Sampling 2-10
2.4 Laboratory Procedures 2-13
3. MEASUREMENT RESULTS 3-1
3.1 Site Locations and Test Results 3-1
3.2 Quality Assurance Data 3-9
4. MODEL ANALYSES AND MAP COMPARISONS 4-1
4.1 Model Analyses of Radon Protection Category 4-1
4.2 Generalized Model-Map Comparisons 4-11
4.3 Summary of Model-Map Comparisons 4-15
5. LITERATURE REFERENCES 5-1
Appendix RAETRAD-F Analyses Using Borehole Gamma Ray A-l
Estimates of Radium Concentrations
iv
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LIST OF FIGURES
Number Page
2-1 DCA letter requesting permission for site access. 2-7
2-2 Field sampling locations. 2-9
2-3 Soil sampling from auger cuttings. 2-11
3-1 Comparison of laboratory assays with borehole measurements 3-2
and gamma probe calibration.
4-1 RAETRAD-F printout for the Polk-1 site. 4-2
4-2 RAETRAD-F printout for the Polk-2 site. 4-3
4-3 RAETRAD-F printout for the Sumter-1 site. 4-4
4-4 RAETRAD-F printout for the Sumter-2 site. 4-5
4-5 RAETRAD-F printout for the Hernando site. 4-6
4-6 RAETRAD-F printout for the Wakulla site. 4-7
4-7 RAETRAD-F printout for the Jefferson site. 4-8
4-8 Comparison of radon protection map and RAETRAD-F data domains 4-13
4-9 Comparison of radon protection map and shifted RAETRAD-F 4-14
data domains.
v
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LIST OF TABLES
Number Page
2-1 SCS soil texture classes 2-4
3-1 Locations of the test sites 3-1
3-2 Radium assays of the borehole soil samples 3-3
3-3 Radium estimated from the borehole gamma ray measurements 3-4
3-4 Water contents of the borehole soil samples 3-5
3-5 Textural classifications of the borehole soil samples 3-6
3-6 Radium, water, and texture of surface soil samples 3-7
3-7 Soil density, radon, and water table measurements 3-8
3-8 Comparison of duplicate radium assays to analytical precision 3-10
3-9 Replicate radium assays of the blank sample 3-11
3-10 Replicate radium assays of the radium standard 3-11
4-1 Potential radon concentrations and site radon potential categories 4-9
from RAETRAD-F analyses.
vi
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1. INTRODUCTION
1.1 BACKGROUND
Radon (222Rn) gas from the decay of naturally occurring radium (226Ra) in soils can enter buildings
through their foundations. If the radon entry rate is elevated and the building is not well ventilated, radon
can accumulate to levels that can significantly increase the occupants' risks of lung cancer with chronic
exposure. The degree of health risk is proportional to the long-term average level of radon exposure. The
U.S. Environmental Protection Agency (EPA) attributes 7.000 to 30,000 lung cancer fatalities annually to
radon, and recommends remedial action if indoor radon levels average 4 picocuries per liter (pCi L" ) or
higher (EPA92a; EPA92b).
The Florida Department of Community Affairs (DCA), under the Florida Radon Research Program
(FRRP), has developed radon-protective building standards. For residences, these standards arc given in the
Florida Standard for Passive Radon-Resistant New Residential Building Construction (DCA95). This
standard requires passive radon barriers in counties that adopt the standard. An earlier version of the
standard (DCA94) contained more detailed requirements for both passive and active radon controls in areas
identified by a radon protection map to have elevated radon potential. Although no longer part of the
adopted standard, the radon protection map and the related system for selecting different levels of radon
control still provide useful guidance for residential radon control.
The radon protection map that is referenced frequently in this report (Nie91) was developed by
calculating the soil radon potentials for each of 3,919 regions of Florida from soil, geological, radiological,
and hydrological properties. 1'he regions w ere defined by the digital intersection of soil maps and surface
geology maps. The radon potentials were expressed as the rate of radon entry into a reference slab-on-grade
house thai was numerically simulated to be located in each of the regions. The regions were then classified
into low, intermediate, and elevated radon potoential categories, depending on whether indoor radon levels
for the reference house could range as high as 4 pCi L"1, as high as 8.3 pCi L"', or greater than 8.3 pCi L"1.
A protocol was also developed under the FRRP (Nie94b) for measuring the soil radon potential
category of specific sites in a way thai corresponds to the radon protection map designations (Nie94).
1-1
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However, the protocols for site-specific tests were designed to represent areas of one acre (4x10 ' nr) or less,
compared with the 8,800-acre (3.6xl0? rrr) regions typically shown on the radon protection map. The site-
specific measurements were designed to supersede the regional map designations because of the inherent
applicability of on-site measurements. For example, a prospective builder may suspect anomalous conditions
at a site (from previous land use, soil or mineral observations, etc.) that could increase its radon potential
above the mapped category. Alternatively, the builder may have reason to suspect that the land has lower
radon potential than its conservatively mapped category, leading him to want to reduce or eliminate radon
controls unless they are specifically needed. In either case, site-specific tests could lead to a more reliable
decision.
The site-specific measurement protocol utilizes model analyses that are identical to those used to
develop the radon protection map (Nie96). However, the site-specific protocol has not been previously
evaluated by field measurements to determine its consistency with the radon protection map.
1.2 OBJECTIVE AND SCOPE
This report examines the consistency of the site-specific radon potential measurement protocol with
the Florida radon protection map. It also presents and evaluates a simplified alternative method for
estimating soil radium profiles for use in the protocol. The consistency between the site-specific
measurements and the map is examined from a series of benchmark measurements using the site-specific
protocol in different Florida regions that lie within the red, yellow, and green areas of the radon protection
map. The measurements, including both field measurements and field sampling of soils for laboratory
measurements, follow the site-specific protocols. The resulting data are analyzed by the RAETRAD-F
computer code, which was developed for analyzing Florida measurements of site radon potential. The results
of these analyses indicate the radon protection category of each benchmark measurement site, which is
compared with the designation given for the site by the radon protection map.
Because of the limited time and budget for evaluating the site-specific protocol, only its primary
aspects were tested. For example, the protocol requires testing after completion of any soil contouring or
other activities that could affect the water table or soil distribution. The generic tests conducted in this study
were performed primarily on undeveloped land, which was typical of land being used for construction in
1-2
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some of the areas but which may have required conlouring before construction in others. The requirement
for locations representative of planned or potential building locations also was satisfied by some of the sites,
but not necessarily by others.
1-3
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2. SITE-SPECIFIC MEASUREMENTS
The site-specific benchmark measurements in this study followed the draft protocol developed for use
with the residential radon standard (DCA94). Additional measurements also followed a proposed alternative
protocol for characterizing soil radium concentration profiles. The measurements were made at seven Florida
sites. Two of the sites were identified by the radon protection map as having a green radon protection
category, three were identified as having a yellow category, and two were identified as having a red category.
The sites were selected considering the radon potential of the map polygon, its uniformity, the land use and
accessibility of the site, and the permission granted by the site owner or occupant. The field procedures
utilized portable equipment that could be hand-carried onto the site without requiring vehicle-mounted drilling
or measuring equipment. The following sections describe the test protocol, site selection, and field procedures
in more detail.
2.1 TEST PROTOCOL
This section presents the protocol for measuring the radon protection category of specific sites (Nie96).
The protocol requires sampling of site soils and measurement of five parameters from the samples or from Held
measurements: (a) soil 32"Ra concentration, (b) soil density, (c) soil textural classification, (d) 22;Rn
concentration in soil gas, and (e) water table minimum depth and duration.
2.1.1 Site Sampling and Measurements
Sampling of soils at the site shall utilize live boreholes spread over the entire site at locations
corresponding to planned or potential building sites. For sites smaller than 1 acre, sampling shall utilize at
least one borehole for every planned or potential residential building location. If the site consists of an
individual lot for a single building, sampling boreholes may be reduced to as few as one, provided that if only
one borehole is used, it is supplemented with two additional soil samples from locations at least 10 m away
from the borehole location and from each other, and from soils representing the 0-61-cm depth interval.
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Soils shall be collected from each borehole to represent four different depth intervals. The depth
intervals are 0-61 cm, 61-122 cm, 122-183 cm, and 183-244 cm. The borehole samples and any
supplementary samples shall be used for measurement of soil density and for textural classification. The
remaining material from each depth interval may be composited for individual measurements of radium
concentration. The concentrat ion of radon in the soil gas shall be measured at or near each borehole site.
Observations of water table depth may utilize any location(s) on the site or on vicinity property.
2.1.2 Soil 2Z6Ra Concentration
The concentrations of 2,6Ra shall be measured for each depth interval by laboratory assays of the soil
samples or by gamma-ray logging of the boreholes. Laboratory assays shall analyze gas-tight, equilibrated
aiiquots of individual samples using a calibrated gamma-rav spectrometer. The spectrometer shall be
calibrated by analyses of standard reference materials and blanks in the same gas-tight and equilibrated
container configuration as used for the samples. Suitable standard reference materials include soils, ores, or
spiked earthen materials obtained from or prepared from liquid sources from the U.S. Department of
Commerce (National Institute of Standards and Technology), EPA, or other sources approved by the DCA.
The concentrations of 2V'Ra shall be reported individually in pCi g'1 on a dry mass basis.
If M'Ra concentrations are determined by borehole logging, a suitable gamma-ray detector shall be
suspended in each borehole at depths corresponding to the centers of each of the four depth intervals for
individual measurements. Additional measurements at the boundaries of each depth interval may also be
made. A suitable gamma-ray detector is a calibrated gamma scintillation probe or diode-type gamma-ray
spectrometer. Bach measurement shall estimate 2"6Ra or total radium (226Ra + 228Ra) with an uncertainty not
exceeding ±0.3 pCi g'1. The detector shall be calibrated in pCi g"1 on a dry mass basis by comparisons with
laboratory assays as described in this section. Measurements at depth interval boundaries shall be weighted
at 50% of the weights applied to measurements in the centers of depth intervals. Total radium measurements
may be used as conservative estimators of j2r,Ra, or they may be corrected for "sRa contributions only if the
correction is based on explicit calibrated measurements of 2'2Th-chain nuclides such as 228Ra. Potential
interferences by '10K are generally smaller, and may be eliminated implicitly as part of the gamma radiation
background or explicitly by separate 4"K radiation measurements.
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2.1.3 Soil Density
In-situ soil density, if measured, shall be determined from the masses of samples of known volume
(drive cylinder method, ASTM D2937) or by other methods approved by the DCA. Equipment used for the
density measurements shall be suitably calibrated. The soil density measurements shall be reported in g cm"5
on a dry mass basis and may be reported individually (all 20 samples), as averaged by layer (four layer means),
or as averaged for the entire site (one overall mean). Because of the relatively low sensitivity of indoor radon
levels to soil density, the soil density need not be measured. If in-situ soil density is not measured, a default
value of 1.5 g cm° shall be used in the analyses for computing the site radon protection category.
2.1.4 Soil Textural Classification
Thetextural classification of the site soils shall utilize laboratory or field methods (SCS75) to group
the soils into one of the twelve textural classes defined by the U.S. Soil Conservation Service, listed in Table
2-1. The soil textural classes may be reported individually (all 20 samples), as aggregated by layer (four layer
classes, determined from layer-composite samples), or as aggregated for the entire site (determined from one
site-composite sample). If visually distinct classes are diseernable among different samples, the site composite
determination may not be used.
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Because of the conservative results obtained with the sand classification and the
prevalence of sandy soils throughout Florida, the soil textural classification need not be
performed. If the soil textural classification is not performed, a default classification of
"sand" shall be used in the analyses for computing the site radon protection category.
Table 2-1 SCS soil texture classes
1. Sand 5. Sandy clay 9. Clay
2. Loamy sand 6. Loam 10. Silty clay loam
3. Sandy loam 7. Clay loam 11. Silty clay
4. Sandy clay loam 8. Silty loam 12. Silt
2.1.5 Soil ^Rn Concentration
The concentration of 222Rn in soil gas shall be sampled by drawing soil gas from a
driven tube or equivalent sampling system and measuring the 222Rn concentration with a
suitably calibrated radon measurement system. The soil radon measurements shall be
conducted at each borehole location at a depth of 1.2 m or greater. To avoid soil disturbance,
the soil gas samples shall be collected before drilling the boreholes, or afterward provided
they are collected approximately 2-3 m away from the borehole locations. The soil radon
measurement does not directly affect the calculation of radon potential unless the
measurement exceeds the value calculated from the soil radium concentrations.
If ground water is encountered at depths shallower than 1.2 m at the time of field
sampling, the requirement for a soil radon measurement may be waived if (a) there is no
evidence that re-sampling during an alternative season would be successful and (b) soil
surveys or similar studies show that seasonal water table depths come within 0.6 m from the
surface. If either of these conditions is not satisfied, another soil radon measurement shall
be attempted during a different season (3 to 9 months later). If ground water is again
encountered at less than 1.2 m depth, the requirement for a soil radon measurement at the
site shall be waived.
2-4
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2.1.6 Water Table Depth
The depth of the water table at the site shall be specified in a manner that is
consistent with the water table specifications used in developing the residential radon
protection map (Nie95a). For the radon protection map, the minimum (most shallow
seasonal) water table depth (in centimeters) and duration (in months) were specified from
data in the STATSGO data base (SCS91). These data were in turn derived from county soil
survey information, as is typically contained in local county soil survey reports (e.g., Tho85).
If county soil survey reports are used as the data source, the water table data should be
defined from the soil or combinations of soils that comprise the site. Average values shall be
computed to represent the data in cases where ranges are reported (i.e., 70 cm would be
computed to represent a reported water table depth range of 60 to 80 cm).
If local area information is unavailable, or if site-specific measurements are otherwise
to be utilized, water table measurements shall be derived from at least four seasonal
measurements of water table depth at 3-month intervals. The most shallow of these shall
be defined as the minimum water table depth, and a minimum duration of 3 months shall
be defined unless a longer time is indicated by the measurements.
2.1.7 Analysis of Site-Specific Measurements
The site-specific measurement data shall be assembled and analyzed using the
RAETRAD-F computer code (Rog95). The RAETRAD-F code simulates radon entry into the
reference house in a way that corresponds to the calculations performed for the residential
radon protection map. The user shall enter site identification information and the individual
site measurement data. The code then computes the appropriate statistical parameters for
the radium measurements, the annual water table distribution from the water table data, the
soil moistures from the texture and density data, and all other required parameters for
computing the annual average indoor radon distribution for the reference house. From this
distribution, the code computes the 95% confidence limit for the annual average indoor radon
concentration in the reference house (C95). The code then compares C95 to the 4.0-pCi L'1 and
2-5
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8.3-pCi L"1 cut points used in the radon protection map, and designates the site to have low,
intermediate, or elevated radon potential. The RAETRAD-F code prints the user-specified
input parameters, the calculated C95 value, and the site radon potential designation.
2.2 SITE SELECTION
The locations for the benchmark site-specific tests were selected to include different
parts of Florida containing green, yellow, and red regions of the radon protection map. Other
criteria for site selection included representativeness, accessibility, and convenience. The
general color regions were selected from the elevated frequency of red regions in central
Florida, the elevated frequency of yellow regions in north-central Florida, and the nearly
complete dominance of green regions in the panhandle part of Florida. Representativeness
was based on qualitative field judgements that excluded areas that were obviously disturbed
or otherwise atypical of the map polygon. For example, highway embankments that could
contain materials hauled from other regions were excluded. Site accessibility was a critical
factor in site selection. Since the protocol requires five borings to depths of 2.4 m (8 ft) on
an acre, casual sampling along road-side fence lines was precluded, and permission for site
access became more important. Related considerations included avoidance of buried utility
lines, approximate 1-acre minimum areas, and convenient proximity to access roads.
Selection of red sites was dominated by accessibility. The FRRP research site near
Bartow was chosen because of its red polygon location and its ownership by the Florida
Institute of Phosphate Research, which has cooperated with past FRRP studies. An FRRP
large-building study site on an adjacent parcel of land was similarly chosen after obtaining
access permission through Southern Research Institute. Since no FRRP study sites were
identified in yellow polygons, these sites were selected during the field trip, and permission
was obtained at the time of sampling. An explanatory letter from DCA, shown in Figure 2-1,
helped obtain owners' permission to sample their soil. The green sites were planned for
FRRP study areas in Tallahassee, but were moved to nearby Wakulla and Jefferson Counties
because of difficulty in penetrating their hard clayey strata with a light-duty soil auger.
2-6
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STATE OF FLORIDA
DEPARTMENT OF COMMUNITY AFFAIRS
fWKGINCY MANAGEMENT • HOUSING AND COMMUNITY DEVELOPMENT • RESOURCE PLANNING ANO MANAGEMENT
LAWTON CHILES LINDA LOOMIS SHELLEY
ciiu«mr
March 9, 1995
HZMQRAHDPM
TO: Land Owners and Occupants
7E0M: Mo Madani, Planning Manager'*'"
SUBJECT: Land Access to Conduct Soil Tests
The Department of Community Affairs has contracted with the
University of Florida and its subcontractor, Rogers t Associates
Engineering Corporation, to perform a research study for
evaluating procedures allowing testing of land fcr soil radon;
the procedures will provide an alternate method to the proposed
Radon Protection map(s) . The maps are the basis for implementing
the proposed Radon-Resistant Construction Standards, which show
the regicns of Florida that require special radon protection.
Specifically, the DCA is evaluating a site-specific soil test
protocol by comparing actual soil tests with the statewide soil
radon potential map predictions.
An essential part of this research study is the collection of
soil samples and measurements from selected locations in Florida
for benchmark evaluations of the site-specific procedures. This
letter is to inform you of our intent and to ask permission for
our contractors to perform soil sampling for measurement
procedures on your lands. The following conditions apply to
testing:
l. Soil samples will be collected from up to 5 boreholes,
r.ot larger than 4-inches in diameter and not deeper than 8
feet. iThis approach is very similar to current testing
done at building sites for foundation soils tests.] Related
measurements may be made at the borehole locations. Soil
samples removed frcm the property will be disposed of after
testing and will not be returned; the samples are non-
hazardous. The boreholes will be re-filled after sample
collection, and there will be minimal surface disturbance.
Z 7 4 0 CENKIVIiW OHIVE ¦ TALLAHASSEE. FLORIDA liHI-IIH
cmUCAlSlAlKuNlUN MJOiHf'.ifc.lMKiuM** 030-^..'* sw« twndi ftjmr. tipftdi
Figure 2-1. DCA letter requesting permission for site access.
2-7
-------
2. One-time site accesB is required for a period of
approximately 2 to 4 hours. The DCA contractors are insured
for liability from any injury or damage related to this
work; you assume no liability in granting them access to
your property.
3. The results of all measurements and sample analysis is
used anonymously for the DCA's research program as a part of
a geographic database. The name and/or address of the
property, occupant, or land owner is not disclosed publicly
and is not associated with the data maintained by the DCA or
its contractors. If the property owner or occupant requests
a copy of the tests results, the measurements made only at
the subject property will be mailed by the DCA contractor to
the address designated by the owner or occupant.
We appreciate your cooperation in providing them a site for this
important study to allow safe growth and habitation throughout
Florida. If there are any questions concerning these testing
activities, please feel free to contact the Radon Program office
at (904) 921-2313 or my office at (904) 487-1824.
MM/dfr
cc: Mr Stanley Latimer, University of Florida, Department of
Urban and Regional Planning
Mr Kirk K. Nielson, Rogers u Associates Engineering Corp.
Figure 2-1. DCA letter requesting permission for site access (continued).
2-8
-------
The sites where the field sampling and measurement protocols were conducted are
iEustrated in Figure 2-2. The two red-category sites (as designated by the radon protection
map) were located at the FRRP research site (Polk-1) and an adjacent commercial building
property in Bartow (Polk-2). The three yellow-category sites were located in Hernando and
Sumter Counties. The Hernando County site was located in a highway median area that
contained old and apparently undisturbed native soil and vegetation. This site was selected
to test the "smaller than 1 acre" option of the protocol. Accordingly, only three complete
boreholes were drilled on this site. The Sumter County sites were on cleared but otherwise
undisturbed land of a power line corridor (Sumter-1) and on cleared land of an interstate
highway right-of-way (Sumter-2). The two green-category sites were located in Wakulla and
Jefferson Counties. The Wakulla County site was on undisturbed land of a power line
corridor, and the Jefferson County site was on vegetation-cleared land in the margin between
a pine tree farm and a U.S. highway right-of-way.
2-9
-------
2.3 F1KLP PROCF.i) IJ RES
The field sampling and measurement procedures conformed to the FRRP procedures given in
"Standard Measurement Protocols, Florida Radon Research Program," (Wi 191), or to American Society for
Testing and Materials (ASTM) procedures where applicable procedures are given. For other tests or sampling
needs, procedures were based on RAE field and laboratory practices. The field sampling and measurements
were conducted during the period from March 12 to March 15, 1995. This section describes the procedures
used for field measurements and for collection and analysis of the field samples.
2.3.1 Location
The latitude and longitude coordinates of each sampling and measurement site were measured using
a global positioning system (NAV-5000D, Magellan Systems Corp., San Dimas, CA). These coordinates were
subsequently analyzed by the Geographic Information System (GIS) at the University of Florida to positively
determine the radon map polygon in which the tests were conducted. Individual sampling locations at each
site were located at least 10 in apart, generally in an approximately square configuration.
2.3.2 Soil Sampling
At each site, five bore holes were sampled at each of the four prescribed depth increments, and two
additional surface samples (0-61 cm depth) were collected for potential evaluation of the site from fewer
borehole samples (as provided in Section 2.1.1 for small sites). The soil samples were collected from the drill
cuttings of a 5-cm diameter soil auger (model 405.23, Arts Manufacturing & Supply, American Falls, ID) that
was powered by a hand-held gasoline-powered drill (ED-2000, Echo, Inc., Lake Zurich, IL). The auger was
threaded through a 5.5-cm hole in a surface platform that was used to collect and isolate soils from different
depths (Figure 2-3). Upon attaining each incremental sampling depth (as measured on the augers),
the drill was operated full speed without further depth
2-10
-------
advancement to bring all loose cuttings to the surface. The sample was then collected with
a hand trowel from the surface pile of auger cuttings (Figure 2-3). After sample collection,
the remaining material was cleaned from the surface platform before further advancing the
auger to the next sampling depth. For clayey soils, the cuttings adhered to the auger, and
were collected by removing the auger from the hole at regular depth intervals and manually
removing the clayey soils from the auger.
. • S • S • S • % 1% ¦ H MS •% •.% V
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«* ¦ «¦»«¦« «¦ * <•« ouii
**• !*¦ <*• !*• *"• /¦ rf-*• /
• S • S • S • S • S • S • • S • S ¦ S • S •'
^s^Vs\sVsVsVs--.VsCsVsVsi«,-sCsV%V
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s-s»>Vs-s«s-s-s-s-s->-s->->-s-s->-s-*--^«s«s-s-v-v-n->-s«s-s-s-s-s-%-s.
¦«I*« «* « ••• »* « «" • «" • !*• «* • ¦ W • ¦ «" » W • /• «" • /• W*/• -¦ « «*•
(?/•/¦/• a/; / • /• <•«-*?/: -• *«".• '*«" • ^ A-
y«S « N »S «S «_S ¦ S * S «_S « S ¦ S >S ¦ S ¦_N »S ¦ % ¦V_S ¦ S •_ N '_S -*¦ « S 'S '.S 'S 'S »„*¦ '.*> 'S '*^V
V • V; /• <• «7 <• d-« ^ - <" • /« ^ **•
iN*S»SiS«S*S*SiS*S*S*H«%*S*S*VS<'
/.w« «*• /• ¦*« «"• /; * • ^ /• -*• /• /• / • ^ A'
• •> *.>v*.s ¦> • *» ^ •% • s • s • s • %«•»
^ • /V;/¦ /V; «" ¦ «"J" «*; «\* «*¦ /y; A1
S&S 5 cm diameter &;
£&£? soil auger
. ^«vvs*wvsVs*s«vvs«sVv*v'
Figure 2-3. Soil sampling from, auger cuttings.
Samples were immediately sealed into heavy gauge (0.1 mm) re-sealable polyethylene
bags and labeled by site, location, and depth for transport to the EAE laboratory for radium
2-11
-------
assays. Approximately 350 g of soil was collected from each depth increment, and the
remainder was discarded. The discarded cuttings were used to backfill each sampling hole
after the samples were collected and sealed.
A density sample was collected at each site using a thin-walled steel drive cylinder,
as prescribed by ASTM D2937 (Wil91). The cylinder was inserted in the 0-30 cm depth
range, and was then excavated with a hand trowel. After removing excess material from the
cylinder, the measured volume of soil was completely transferred to a heavy gauge (0.1 mm)
re-sealable polyethylene bag for weighing and moisture measurement in the laboratory.
Soil textural classifications were made from visual and tactile observations while
bagging the auger cuttings for the radium samples. Water table depths similarly were
observed, where possible, by measuring the distance from the soil surface to the surface of
the water that occurred in the borehole prior to backfilling. Where water was not observed,
estimates were obtained subsequently from the data used for the state-wide radon maps
(Nie95a).
Soil radon measurements were made from soil gas drawn from a depth of
approximately 1 m using the internal pump in a portable radon monitor (AB-5, Pylon
Electronics Inc., Ottawa, ON, Canada). The gas was drawn through a 6 mm I.D. steel pipe
driven into the soil and connected by plastic tubing to the scintillation cell (110A, Pylon
Electronics Inc., Ottawa, ON, Canada) and pump of the radon monitor. The monitor drew
approximately 2 L min"1 of soil gas, and was operated for several minutes before connecting
to the pipe to establish background. After connection to the soil gas pipe, the sampler was
operated for approximately 10 to 35 minutes, after which the plastic tube was disconnected
from the pipe to purge the cell with surface air. The alpha activity in the scintillation cell
was counted over 2-minute intervals. Soil gas radon concentrations were computed from the
continuously measured alpha counts using the calibration method and equations of Thomas
and Countess (Tho79). The efficiency of the scintillation cell was determined previously from
calibration analyses at the U.S. Department of Energy's Technical Measurement Center
radon chamber at Grand Junction, CO.
2-12
-------
Borehole gamma ray logs were measured before backfilling each hole for comparison
with the results of laboratory radium assays. The borehole logs utilized a 2.5-cm diameter
sodium iodide gamma-ray scintillation probe connected to a digital scaler (Models 44-3 and
2220, Ludlum Measurements, Inc., Sweetwater, TX). Individual 1-min counts were recorded
at 30.5-cm intervals throughout the depth of each borehole. The same probe was calibrated
in a separate study (Nie95b) to yield 4,600 counts min"1 in boreholes with 2.1 pCi g"1 226Ra
and 0.2 pCi g'1 228Ra and a background rate of 590 counts min"1 in low-radium boreholes.
2.4 LABORATORY PROCEDURES
The bore-hole soil samples were each weighed into tared steel cans and sealed for
radium assay by the procedures described previously (Nie95a). The radium assays were
performed after approximately 18 days equilibration. At least 10% duplicates, blanks, and
standards were also analyzed for quality assurance purposes. Samples were dried as
specified by ASTM D 2216-80 (Wil91), and the results were reported on a dry-mass basis.
The soil density samples were completely transferred to laboratory beakers and dried as
specified by ASTM D 2216-80 to determine dry sample density according to ASTM D 2937-83
(Wil91).
2-13
-------
3. MEASUREMENT RESULTS
This chapter identifies the locations where site-specific measurements were performed
and presents the results of the measurements and the supporting quality assurance data.
3.1 SITE LOCATIONS AND TEST RESULTS
The locations of each site and the results of the site-specific tests and laboratory
analyses of field samples are presented in this section. The latitude and longitude
coordinates of each test site are presented in Table 3-1, as they were measured by the global
positioning system during the field sampling activities. The single coordinates correspond
to an approximate centroid among the five site boreholes.
Table 3-1. Locations of the test sites.
Site
Latitude
Longitude
Polk-1
27° 53.676' N
81° 51.918' W
Polk-2
27° 53.765' N
81° 51.925' W
Sumter-1
28° 52.849' N
82° 05.238' W
Sumter-2
28° 56.095' N
82° 06.664' W
Hernando
28° 33.209' N
82° 18.129' W
Wakulla
30° 11.299' N
84° 11.484' W
Jefferson
30° 20.405' N
84° 00.935' W
Soil radium concentrations measured by laboratory assays of the borehole soil samples
are presented in Table 3-2. The borehole gamma ray measurements at the centers of each
sample depth interval are compared with the corresponding laboratory radium measurements
in Figure 3-1. The scatter of the individual borehole measurements gives a correlation
coefficient of r2 = 0.84 for the least-squares regression of radium on gamma ray intensity.
The least-squares fitted line is also compared with an independent calibration of the gamma
3-1
-------
ray probe, which is shown by the solid line in Figure 3-1. The independent calibration was
used to estimate radium concentrations for each gamma ray measurement, and the resulting
radium concentrations were averaged for each depth interval to obtain the comparison
radium concentrations presented in Table 3-3. The averages and uncertainties in Table 3-3
weight the center measurement in each depth interval twice as much as measurements at
the interval boundaries (neglecting the top surface boundary). Measured soil water contents
and textural classifications for the depth intervals in each borehole are presented in Tables
3-4 and 3-5, respectively.
10'
o
^Q.
c
O
¦£?
CO
1
C
©
o
tz
o
o
E
3
TD
nJ
DC
10
10'
10
-1
° 119 Florida soil measurements
—- Ra = 0.000668g - 0.49 (least squares r2=0.84)
— Ra = 0.000637g - 0.63 (SLC calibration)
10'
' * '
10° 10'
Gamma ray intensity (counts/min)
"5.
d
<3
X
CD
10'
Figure 3-1. Comparison of laboratory assays with borehole measurements
and gamma probe calibration.
3-2
-------
Table 3-2. Radium assays of the borehole soil samples
Site nnri Soil Radium Concentration (pCi g"1 ± 1 s.tL°)
Depth (cm)
Borehole 1
Borehole 2
Borehole 3
Borehole 4
Borehole 5
Polk-1
0 - 61
4.3 ± 0.3
4.2 ± 0.3
6.1 ± 0.3
6.2 ± 0.3
4.7 ± 0.3
61 - 122
7.1 ± 0.3
5.2 ± 0.3
. 4.2 ± 0.2
7.2 ± 0.3
5.4 ± 0.3
122 - 183
5.6 ± 0.3
6.5 ± 0.2
9.0 ± 0.2
6.2 ± 0.3
4.4 ± 0.2
183 - 244
5.0 ± 0.2
4.9 ± 0.2
5.4 ± 0.3
5.2 ± 0.3
5.3 ± 0.2
Polk-2
0 - 61
9.7 ± 0.3
2.3 ± 0.2
15.8 ± 0.3
8.1 ± 0.3
20.8 ± 0.3
61 - 122
4.8 ± 0.2
3.1 ± 0.2
18.0 ± 0.3
5.0 ± 0.3
10.2 ± 0.3
122 - 183
4.4 ± 0.2
1.7 ± 0.2
9.3 ± 0.3
3.4 ± 0.3
13.4 ± 0.3
183 - 244
2.4 ± 0.2
7.3 ± 0.3
3.1 ± 0.2
4.6 ± 0.2
6.5 ± 0.3
Sumter-1
0-61
0.8 ± 0.2
0.9 ± 0.2
1.0 ± 0.2
0.5 ± 0.2
0.8 ± 0.2
61 - 122
0.7 ± 0.2
0.8 ± 0.2
0.8 ± 0.2
0.6 ± 0.2
0.1 ± 0.2
122 - 183
0.3 ± 0.2
0.7 ± 0.2
1.7 ± 0.2
0.9 ± 0.2
0.5 ± 0.2
183 - 244
2.3 ± 0.3
1.9 ± 0.2
3.4 ± 0.3
1.0 ± 0.2
4.0 ± 0.3
Sumter-2
0-61
0.6 ± 0.2
0.6 ± 0.2
0.5 ± 0.2
0.2 ± 0.2
0.4 ± 0.2
61 - 122
0.5 ± 0.2
0.6 ± 0.2
0.5 ± 0.2
0.4 ± 0.2
0.5 ± 0.2
122 - 183
0.6 ± 0.2
0.5 ± 0.2
0.6 ± 0.2
0.3 ± 0.2
0.3 ± 0.2
183 - 244
1.6 ± 0.2
1.6 ± 0.3
1.1 ± 0.2
3.4 ± 0.3
0.5 ± 0.2
Hernando
0 - 61
0.8 ± 0.2
0.9 ± 0.2
0.7 ± 0.2
b
—
61 - 122
0.5 ± 0.2
0.7 ± 0.2
0.5 ± 0.2
...
—
122 - 183
1.3 ± 0.2
1.0 ± 0.2
0.4 ± 0.2
...
—
183 - 244
3.5 ± 0.3
2.5 ± 0.3
1.0 ± 0.2
—
—
Wakulla
0-61
0.8 ± 0.2
0.6 ± 0.2
0.9 ± 0.2
1.3 ± 0.2
0.8 ± 0.2
61 - 122
0.7 ± 0.2
0.6 ± 0.2
0.9 ± 0.2
1.7 ± 0.3
0.9 ± 0.2
122 - 183
2.0 ± 0.3
1.1 ± 0.3
0.5 ± 0.2
2.1 ± 0.3
2.4 ± 0.3
183 - 244
2.2 ± 0.3
1.3 ± 0.3
0.9 ± 0.2
0.8 ± 0.3
2.4 ± 0.3
Jefferson
0-61
0.3 ± 0.3
0.6 ± 0.3
0.6 ± 0.3
0.4 ± 0.2
0.5 ± 0.2
61 - 122
0.7 ± 0.3
0.6 ± 0.2
0.4 ± 0.2
0.8 + 0.2
0.6 * 0.2
122 -183
1.0 ± 0.2
0.6 ± 0.2
0.8 ± 0.2
0.7 ± 0.2
0.3 ± 0.2
183-244
0.9 ± 0.3
0.8 ± 0.3
0.8 ± 0.3
0.8 ± 0.3
0.6 ± 0.2
°1 standard deviation uncertainties, as computed from gamma-ray counting statistics.
60nly three complete boreholes were sampled at this site.
3-3
-------
Table 3-3. Radium estimated from the borehole gamma ray measurements
Soil Radium Concentration (pCi ± 1 s.cLa)
Site and
Depth (cm) Borehole 1 Borehole 2 Borehole 3 Borehole 4 Borehole 5
Polk-1
0 - 61
61 - 122
122 - 183
183 • 244
Polk-2
0-61
61 - 122
122 - 183
183 - 244
Sumter-1
0-61
61 - 122
122 - 183
183 - 244
Sumter-2
0-61
61 - 122
122 - 183
183 - 244
Hernando
0 - 61
61 - 122
122 - 183
183 - 244
Jefferson
0 - 61
61 - 122
122 - 183
183 - 244
3.2 x 0.3
5.4 ± 1.3
5.7 ± 0.6
4.3 ± 0.7
4.3 x 1.0
3.1 ± 0.3
2.7 ± 0.4
3.5 ± 1.5
0.6 ±0.3
0.7 ± 0.3
1.1 ± 0.7
3.0 ± 0.6
0.4 4 0.3
0.4 * 0.3
0.5 ± 0.3
1.7 x 1.0
0.7 ± 0.3
1.2 ± 0.5
2.7 x 0.6
3.4 ± 0.3
0.3'x 0.3
0.5 ± 0.3
0.9 ± 0.3
1.0 ± 0.3
3.5 * 0.3
4.5 ± 0.8
5.4 ± 0.9
5.0 ± 1.1
4.4 ± 0.4
3.3 x 0.7
3.1 ± 0.9
5.1 x 0.5
0.8 a 0.3
1.0 x 0.3
1.5 ± 0.7
7.7 ± 4.1
0.4 ± 0.3
0.5 x 0.3
1.1 * 0.8
2.6 ± 0.3
1.0 * 0.3
2.4 x 0.9
3.4 t. 0.3
3.4 ± 0.3
0.3 x 0.3
0.4 ± 0.3
1.0 x 0.3
1.2 x 0.3
4.4 x 0.8
4.0 ± 0.9
5.7 x 1.2
4.0 ± 0.3
12.9 ± 0.3
11.6 * 1.4
7.5 ± 2.6
4.6 x 1.1
0.6 ± 0.3
0.8 ± 0.3
1.9 ± 1.4
5.3 * 0.9
0.4 x 0.3
0.5 ± 0.3
0.6 ± 0.3
1.5 ± 0.4
0.5 x 0.3
0.5 ± 0.3
0.5 x 0.3
1.3 ± 0.4
0.3 x 0.3
0.4 ± 0.3
0.9 x 0.3
1.1 ± 0.3
3.9 ± 0.3
5.1 ± 0.7
4.7 ± 0.8
3.5 ± 0.3
4.5 ± 3.2
4.5 ± 2.5
3.3 ± 0.6
6.1 ± 1.7
0.4 ± 0.3
0.5 ± 0.3
0.5 ± 0.3
0.7 ± 0.3
0.4 ± 0.3
0.4 ± 0.3
0.5 ± 0.3
2.0 ± 0.9
0.3 ± 0.3
0.6 ± 0.3
1.3 * 0.3
1.4 ± 0.3
5.1 11.4
5.3 ± 1.1
4.1 ± 1.2
3.4 ± 0.3
13.2 ± 1.3
13.2 ± 2.8
13.1 ± 3.3
8.3 ± 1.5
0.6 x 0.3
0.6 * 0.3
0.7 ± 0.3
2.1 x 1.4
0.3 ± 0.3
0.4 t 0.3
0.3 x 0.3
0.3 ± 0.3
0.3 ± 0.3
0.2 x 0.3
0.4 x 0.3
0.4 ± 0.3
31 standard deviation uncertainties computed from measurement variations within depth
intervals and gamma ray counting statistics.
''Only three complete boreholes were sampled at this site.
3-4
-------
Table 3-4. Water contents of the borehole soil samples
Site and Water Content (% of dry mass)
Depth (cm) Borehole 1 Borehole 2 Borehole 3 Borehole 4 Borehole 5
Polk-1
0 - 61 5.4 4.7
61 - 122 6.2 5.8
122 - 183 6.2 6.6
183 - 244 5.2 4.4
Polk-2
0 - 61 7.5 4.5
61 - 122 5.0 6.7
122 - 183 5.5 6.0
183 - 244 4.9 9.1
Sumter-1
0 - 61 5.2 6.0
61 - 122 4.3 4.6
122 - 183 3.7 3.9
183 - 244 10.6 7.7
Sumter-2
0 - 61 5.5 4.7
61 - 122 4.7 4.1
122 - 183 3.6 3.6
183 - 244 10.7 11.5
Hernando
0 - 61 5.7 6.0
61 - 122 4.5 5.3
122 - 183 9.5 5.6
183 - 244 14.6 13.0
Wakulla
0 - 61 14.0 14.3
61 - 122 16.4 20.7
122 - 183 31.3 45.7
183 - 244 39.9 54.1
Jefferson
0 - 61 6.1 5.8
61 - 122 5.7 6.1
122 - 183 11.5 12.0
183 - 244 16.3 18.8
4.3 6.0. 4.2
4.5 5.0 4.9
5.5 5.9 5.2
5.3 5.6 5.1
11.8 7.5 11.5
9.7 5.9 10.4
9.4 5.5 11.2
5.9 4.5 8.6
7.0 5.5 4.8
4.5 4.4 4.5
9.0 4.4 4.1
13.1 7.7 11.9
4.8 6.4 4.7
4.2 5.2 4.2
3.2 3.7 3.3
8.8 13.3 7.0
9.7
5.9
5.0
10.0 .
16.4 23.8 18.5
16.3 27.3 20.6
16.2 32.9 53.7
20.1 61.3 51.6
6.5 6.1 6.2
9.8 7.0 6.4
14.5 13.8 12.9
16.5 25.3 16.6
"Only three complete boreholes
were sampled at this site.
-------
Table 3-5. Textural classifications of the borehole soil samples
Site and Textural Classification
Depth (cm)
Borehole 1
Borehole 2
Borehole 3
Borehole 4
Borehole 5
Polk-1
0 - 61
Sand
Sand
Sand
Sand
Sand
61 - 122
Sand
Sand
Sand
Sand
Sand
122 - 183
Sand
Sand
Sand
Sand
Sand
183 - 244
Sand
Sand
Sand
Sand
Sand
Polk-2
0-61
Sand
Sand
Sandy Loam
Sand
Sandy Loam
61 - 122
Sand
Sand
Loamy Sand
Sand
Sand
122 - 183
Sand
Sand
Sand
Sand
Sand
183 - 244
Sand
Sand
Sand
Sand
Sand
Sumter-1
0-61
Sand
Sand
Sand
Sand
Sand
61 - 122
Sand
Sand
Sand
Sand
Sand
122 -183
Sand
Sand
Sand
Sand
Sand
183 - 244
Loamy Sand
Sand
Sandy Loam
Sand
Loamy Sand
Sumter-2
0-61
Sand
Sand
Sand
Sand
Sand
61 - 122
Sand
Sand
Sand
Sand
Sand
122 - 183
Sand
Sand
Sand
Sand
Sand
183 - 244
Sand
Loamy Sand
Sand
Sandy Loam
Sand
Hernando
0-61
Sand
Sand
Sand
a
—
61 - 122
Sand
Sand
Sand
—
—
122 - 183
Loamy Sand
Sand
Sand
...
—
183 - 244
Sandy Loam
Loamy Sand
Sand
—
—
Wakulla
0 - 61
Sa CI Loam
Sa CI Loam
Sandy Clay
Clay
Clay Loam
61 - 122
Sandy Clay
Clay
Sandy Clay
Clay
Clay
122 - 183
Clay
Clay
Sandy Clay
Clay
Clay
183 - 244
Clay
Clay
Clay
Clay
Clay
Jefferson
0 - 61
Sand
Sand
Sand
Sand
Sand
61 - 122
Sand
Sand
Sand
Sand
Sand
122 - 183
Loamy Sand
Loamy Sand
Sandy Loam
Loamy Sand
Loamy Sand
183 - 244
Sandy Loam
Sandy Clay
Sandy Loam
Clay Loam
Sandy Loam
"Only three complete boreholes were sampled at this site.
3-6
-------
The radium profiles at undisturbed sites show a general trend of increasing
concentration with depth, while radium at the reclaimed-land sites (Polk-1 and Polk-2) shows
a more uniform or decreasing concentration with depth. The trends in water contents and
textural classes show a tendency toward sandy cover soils over wetter, finer-grained soils at
depth for the undisturbed sites. The radium concentrations, water contents, and textural
classifications in the supplemental surface soil samples, as described in section 2.1.1, are
presented in Table 3-6. These properties are generally consistent with the surface (0 to 61
cm depth) soil properties in Tables 3-2 through 3-5.
Table 3-6. Radium, water, and texture of surface soil samples
Surface Location 1 Surface Location 2
Site
Radium"
Water*
Texturec
Radium"
Water6
Texture0
Polk-1
4.7 ± 0.3
5.7
Sand
5.1 ± 0.3
3.0
Sand
Polk-2
11.7 ± 0.3
10.7
Sand
10.8 ± 0.3
5.6
Sand
Sumter-1
3.2 ± 0.3
8.3
Sand
0.9 ± 0.2
5.1
Sand
Sumter-2
0.6 ± 0.2
4.7
Sand
0.6 ± 0.2
5.3
Sand
Hernando
1.0 ± 0.2
4.6
Sand
1.0 ± 0.2
8.8
Sand
Wakulla
0.6 ± 0.2
20.5
Clay
0.8 ± 0.2
15.6
Clay
Jefferson
0.6 ± 0.2
6.7
Sand
0.4 ± 0.3
6.3
Sand
°pCi g"1 dry basis ± 1 standard deviation (uncertainty computed from counting statistics).
^Percent of dry soil mass.
CSCS soil texture class (SCS75).
The results of the soil density, soil radon, and water table measurements are
presented in Table 3-7. The density measurements represent single samples at each site.
The soil radon measurements similarly represent individual sampling locations. However,
the concentrations represent averages of multiple counting intervals, from which the standard
deviations were calculated. The water table was only observed at the Wakulla site; therefore
the minimum depths and durations were primarily estimated from the Statsgo data (SCS91)
used previously in developing the Florida radon maps (Nie95a).
3-7
-------
Table 3-7. Soil density, radon, and water table measurements.
Water Table
Soil Density Soil Radon Minimum Duration6
Site
(g cm"3)
(pCi L1)0
Depth (cm)
(months)
Basis*1
Polk-1
1.60
1,600 ± 230
2,980 ± 60
152
3
Statsgo 110
Polk-2
1.62
1,360 ± 150
4,130 ± 150
152
3
Statsgo 110
Sumter-1
1.49
684 ± 75
183
6
Statsgo 120
Sumter-2
1.51
515 ± 54
183
6
Statsgo 120
Hernando
1.43
1,200 ± 60
183
6
Statsgo 121
Wakulla
1.68
15 * ld
61
12
Statsgo 45 &
Field Meas.
Jefferson
1.41
91 ± 26
183
6
Statsgo 40
"From soil gas sample drawn from 1 m depth.
^Duration of high water table level.
"Water table data for the indicated Statsgo soil map units (Nie95a) or measurements.
^Incomplete sample owing to impermeable soil.
3-8
-------
3.2 QUALITY ASSURANCE DATA
The 152 radium assays reported in Tables 3-2 and 3-6 were performed according to
the protocols presented in Nie95a. These protocols have previously achieved prescribed
standards of precision and accuracy (Nie95a). To demonstrate similar achievement of the
same data quality objectives, additional analyses were performed to determine the precision
and accuracy of the present radium assays. The extra analyses included approximately 10%
duplicate assays, 10% blanks, and 10% replicate analyses of standards.
Two separate estimates of analytical precision were obtained from the radium assay
data. The first is estimated from the average statistical precision of each assay. Expressing
the precision as a relative standard deviation (standard deviation -r mean), the average of all
assays for samples exceeding 2 pCi g"1 was 6.0%, compared to a data quality objective of 20%
for this parameter. The second estimate of analytical precision was determined from the
analyses of duplicate assays, which are reported in Table 3-8. The differences among
duplicates, reported in the last column of Table 3-8, were averaged to obtain 0.0 pCi g'1,
which is an indication of no net bias. The average absolute difference, 0.2 pCi g"1, indicates
the average absolute agreement between the pairs of analyses. The relative standard
deviation between the pairs of duplicate analyses was 4.3%, well within the 20% precision
objective even though only 7 of the 16 pairs of duplicate assays exceeded 2 pCi g"1. The
relative standard deviation was computed as
RSDdup = \,2nI(x1-x//I(x1+x2) (1)
where
RSDdup =
X1
X2
n =
3-9
relative standard deviation among duplicates
first observation
second observation
number of pairs being compared.
-------
Table 3-8. Comparison of duplicate radium assays to analytical precision.
Sample
Duplicate Assay
Radium ± uncertainty
(pCi g"1)
Reference Radium
Concentration
(pCi g-1)
Difference
(pCi r1)
Polk-1, H-l, 4-6
5.8 ± 0.3
5.6
0.2
Polk-1, H-5, 4-6
4.6 ± 0.2
4.4
0.2
Polk-2, H-3, 2-4
18.0 ± 0.3
18.0
0.0
Polk-2, H-4, 6-8
4.7 ± 0.2
4.6
0.1
Polk-2, H-5, 0-2
20.5 ± 0.3
20.8
-0.3
Polk-2, H-5, 2-4
10.4 ± 0.2
10.2
0.1
Hernando, H-2, 2-4
0.8 ± 0.2
0.5
0.3
Hernando, H-5, 0-2
0.8 ± 0.2
0.7
0.1
Sumter-1, H-2, 0-2
o
00
14
O
to
0.9
-0.1
Sumter-1, H-4, 4-6
0.3 ± 0.2
0.9
-0.6
Sumter-2, H-l, 0-2
0.4 ± 0.2
0.6
-0.2
Sumter-2, H-5, 0-2
0.4 ± 0.2
0.4
0.0
Wakulla, H-2, 2-4
0.5 ± 0.2
0.6
0.0
Wakulla, H-4, 4-6
1.6 ± 0.3
2.1
-0.5
Jefferson, H-3, 2-4
o
'-3
1+
O
to
0.4
0.3
Jefferson, H-5, 6-8
0.5 ± 0.2
0.6
-0.2
Average Difference (pCi g"1)
Average Absolute Difference (pCi g'1)
Relative Std. Dev. (all 16 pairs)
0.0
0.2
4.3%
Estimates of accuracy were made from analyses of blanks and from analyses of
standards. The analyses of blanks utilized a 300 g aliquot of onyx rock that had been
previously determined by extended counting to contain negligible quantities of radium or
thorium (<0.1 pCi g'1). The blank sample was sealed in a can identical to those used for the
soil samples, and was counted repeatedly during the periods of sample analysis. The results
of these counts are presented in Table 3-9. The average quantity of radium measured in the
blank was 0.1 ± 0.2 pCi g"1, well within the analytical standard deviation of ±0.2 pCi g"1.
3-10
-------
Table 3-9. Replicate radium assays of the blank sample.
^Ra ± s.d.
(pCi g'1)
226Ra ± s.tL
(pCi g-1)
226Ra ± s.d.
(PCi g-1)
226Ra ± s.d.
(pCi g-1)
0.0 ± 0.2
0.5 ± 0.2
0.0 ± 0.2
0.1 ± 0.2
0.4 ± 0.2
0.0 ± 0.2
0.1 ± 0.2
0.1 ± 0.2
0.3 ± 0.2
0.3 ± 0.2
¦ 0.3 ± 0.2
0.0 ± 0.2
0.3 ± 0.2
0.3 ± 0.2
0.1 ± 0.2
-0.2 ± 0.2
-0.3 ± 0.2
Average:
0.1 ± 0.2
The accuracy goal for the radium assays was to demonstrate agreement of better than
± 10% with standard reference materials. The reference material used with these analyses
was prepared and distributed by the U.S. Department of Energy's Division of Remedial
Action Projects through their Technical Measurements Center, which was operated by Bendix
Field Engineering Corp. in Grand Junction, CO. The standard was certified to contain 15.12
± 0.23 pCi g"1 of Z26Ra. It was sealed into a can identical to those used for the soil samples,
and was counted at various times during the period when the soil samples were counted. The
results of the assays on the standard are presented in Table 3-10. Their average bias of only
2% was well within the 10% accuracy goal, and demonstrates acceptable accuracy for this
study.
Table 3-10. Replicate radium assays of the radium standard.
226Ra±s.d. 226Ra±s.d. 226Ra±s.d. 22GRa±s.d.
(pCi g*1) Ra/Ref. (pCi g'1) Ra/Ref. (pCi g"1) Ra/Ref. (pCi g*1) Ra/Ref.
15.7 ± 0.4
1.036
15.8 ± 0.4
1.048
15.7
0.4
1.036
15.4
±
0.4
1.022
15.3 ± 0.4
1.010
15.1 ± 0.4
0.997
15.5
¦jr
0.4
1.022
15.6
0.4
1.032
15.1 ± 0.4
0.999
15.5 ± 0.4
1.023
15.4
0.4
1.021
15.4
±
0.4
1.016
15.6 ± 0.4
1.034
15.6 ± 0.4
1.031
15.5
0.4
1.023
14.9
¦±
0.4
0.982
15.2 ± 0.4
1.005
Average:
15.4
¦+
0.3
1.020
± 0.017
3-11
-------
4. MODEL ANALYSES AND MAP COMPARISONS
The measurements presented in Chapter 3 were analyzed with the RAHTRAD-F model (Rog95) to
determine the radon potential category of each site. These determinations were then compared with the
categories assigned by the radon protection map. More general sensitivity analyses were also performed with
the RACTRAD-F model to assess the general agreement between the site-specific modeling approach and the
state-wide radon protection map classifications.
4.1 MODEL ANALYSES OF RADON PROTECTION CATEGORY
The measurements from each of the seven sites were analyzed by the RAETRAD-F model as
described in Section 2.1.7 to determine their site radon potential category. Radium distributions were entered
for all five boreholes from six of the sites to represent a 1 -acre parcel of land. For the Hernando County site,
the three completed boreholes were used to represent a half-acre area (Nie96). Corresponding soil texture
classes were used as listed in Table 3-5, and soil density, soil radon, and water table data were used as listed
in Table 3-7. The resulting printouts from the RAETRAD-F code for each analysis are presented in Figures
4-1 through 4-7 for the respective Polk-1, Polk-2, Hernando, Sumter-1, Sumter-2, Wakulla, and Jefferson
County sites.
4-1
-------
Analysis of Site Test Data for
RESIDENTIAL RADON CONTROL CATEGORY CLASSIFICATION
using RAETRAD-F v.1.1
written by
Rogers & Associates Engineering Corporation
SITE Location: 27.8546 Deg N, SI.8653 Deg W
County: Polk Run Date: 4-14-1995
State: Florida Run Time: 8:31
Zipcocie: User: Rodger Holt
INPUT DATA Measured by: RAE
Average Site Dry Density (g/cc): 1.605
Average Site Soil Texture: Sand
Radium Concentrations (pCi/g)
Depth
Hole 1
Hole 2
Hole 3
Hole 4
Hole 5
0
- 2 ft
4 .30
4.20
6.10
6.20
4 .70
2
- 4 ft
7.1C
5.20
4 .20
7.20
5.40
4
- 6 ft
5.6C
6.50
9.00
6.20
4.40
6
- e ft
5.00
4 . 90
5.40
5.20
5 .30
Soil Radon Concentrations (pCl/L)
Sample 1 Sample 2
1600.0 2978.C
Water Table Depth (ft)
Months Depth
3.CO b.OC
RESULTS +
I
I RESIDENTIAL SITE INDCOR RADON POTENTIAL: 35.2 pCi/I
l
I This site is ir. a
I RED
i radon protection category as referenced by the
; Florida Radon Protection Kao
T certify that the site arc input data are correct r.c the best of rr.y knowledge.
Rodger Holt Agent, for: RAE
Figure 4-1. RAETRAD-F printout for the Polk-1 site.
4-2
-------
Analysis of Site Test Data for
RESIDENTIAL RADON CONTROL CATEGORY CLASSIFICATION
usinc RAF.TRAD-F v. 1.1
written by
Kogc-rs S Associates Engineering Corporation
SITE Location: 27.8961 Deg X, 81.8654 Deg W
County: Polk
State: Florida
Zipcoae:
Run Date: 4-14-1995
Run Time: 8:25
User: Rodger Holt
INPUT DATA Measured by: RAE
Average Site Dry Density (g/cc)
1.616
Radium Concentrations (pCi/g)
Deoth Hole 1 Hole 2 Hole
3 Hole A Hole
0 - 2 ft
9.70
2.30
15.80
8.10
20.80
2 - 4 ft
4 .80
3.10
18.00
5.00
10.20
4 - 6 ft
4.40
1.70
9.30
3.40
13.40
6 - 8 ft
2 . 4C
7.30
3.10
4.60
6.50
Soil Textj
res
Depth
Hole 1
Hole 2
Hole 3
Hole 4
Hole 5
0 - 2 ft
Sand
Sand
SaLon
Sand
SaLom
2 - 4 ft
Sand
Sand
LSar.d
Sand
Sand
4 - 6 ft
Sand
Sand
Sand
Sand
Sand
6 - 8 ft
Sand
Sand
Sand
Sand
Sand
Soil Radon
C on cen t r a t. i on s
(pCi/L)
Sample 1
Sample 2
1363.0
4128. C
Water Table Depth (ft)
Months Depth
3.00
:.00
RESULTS
RESIDENTIAL SIT?. INDOOR RADON POTENTIAL: 104.5 pCi/L
This site is in a
RED
radon protection category as referenced by the
Florida Raccn Protection Mao
I certify that the site and input data are correct to the best of my knowledge.
Rodger Holt Agent for: RAE
Figure 4-2. RAETRAD-F printout for the Polk-2 site.
4-3
-------
Analysis oi Site Test Data for
RESIDENTIAL RADON CONTROL CATEGORY CLASSIFICATION
using RAETRAD-F v.1.1
written fcy
Sogers & Associat.es Engineering Corporation
SITE Location: 28.8808 Deg K, 82.0873 Deg W
County: Sumter
State: Florida
Zipcode:
Run Date: 4-14-1995
Run Time: 8:19
User: Rodger Holt
INPUT DATA Measured by: RAE
Average Site Dry Density (q/cc)
Radium Concentrations (pCi/g)
Death
Hole
Hole 2 Hole 3 Hole
1 .490
Hole
0-2 ft
2 - 4 ft
4 - 6 ft
6 - 8 ft
.80
.70
.30
2.30
.90
.80
.70
] .90
1 .00
.80
1 .70
3.40
.50
.60
.90
1.00
.80
.10
.50
4 .00
Soil Textures
Depth Hole
Hole
Hole
Hole 4 Hole
2 ft
4 ft
6 ft
8 ft
Sand
San.d
Sand
LSand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
SaLom
Sand
Sana
Sand
Sand
Sand
Sana
Sand
LSand
Soil Radon Concentrations (pCi/L)
Sample 1
684.0
Water Table Depth
Months Depth
(ft)
6.00
6.00
RESULTS ^ t
I I
I RESIDENTIAL SITE INDOOR RADON POTENTIAL: 8.' pC-i/L I
I . I
I This site is in a 1
I YELLOW I
I radon protection category as referenced by the I
I Florida Radcn Protection Mao |
I " I
+ +
I certify that the site and input data are correct to the best cf my knowledge.
Rodger Holt. Agent fcr: RAE
Figure 4-3. RAETRAD-F printout for the Sumter-1 site.
4-4
-------
Analysis of Site Test Data for
RESIDENTIAL RADCN CONTROL CATEGORY CLASSIFICATION
using RAF.TRAD-F v. 1.1
written by
Rogers & Associates Engineering Corporation
SITE Location: 28.9349 Deg N, 82.1111 Deg K
County: Sumter Run Date: 4-14-1995
State: Florida Run Time: 8:16
Zipcode: User: Rodcer Holt
INPUT DATA Measured by: RAE
Average Site Dry Density (g/cc): 1.509
Radium Concentrations (pCi/g)
Depth Hole 1 Hole 2 Hole 3 Hole 4 Hole 5
0-2
ft
.60
.60
.50
.20
.40
2-4
ft
.50
. 6C
.50
.40
.50
4-6
ft
.60
.50
. 6C
.30
.30
6-8
ft
1.60
: .60
1 .10
3.4C
.50
Soil Textures
Depth Hole 1 Hole 2 Hole 3 Hole 4 Hole 5
0-2
ft
Sand
Sand
Sand
Sand
Sand
2-4
ft
Sand
Sand
Sand
Sand
Sar.d
4-6
ft
Sand
Sand
Sand
Sand
Sand
6-8
ft
Sand
LSand
Sand
SaLcm
Sand
Soil Radon Concentrations (pCi/L)
Sample 1
515.0
Water Table Depth (ft)
Months Depth
6.00 6.CO
RESULTS
RESIDENTIAL SITE INDOCR RADON POTENTIAL:
.7 pCi/L
This site is .in a
GHEEN
raaon protection category as referenced by the
Florida Rador. Protection Map
I certify that, the site and input data are correct to the best of my knowledge.
Rodger Holt Agent for: RAE
Figure 4-4. RAETRAD-F printout for the Sumter-2 site.
4-5
-------
Analysis of Site Test Data for
RESIDENTIAL RADON CONTROL CATEGORY CLASSIFICATION
using RAETRAD-F v.1.1
written by
Rogers & Associates Engineering Corporation
SITF Location: 28.5535 Deg K, 82.3022 Dcg W
County: Hernando Run [>ate: 4-14-1995
State: Florida Run Time: 8:22
Zipcoce: User: Rodger Hoi;
INPUT DATA Measured by: RAE
Average Site Dry Density (g/cc): 1.433
Radium Concentrations (pCi/g)
Depth
Hole 1
Hole 2
Hole 3
0
- 2 ft
.80
.90
.70
2
- 4 ft
.50
.70
.50
A
- 6 ft
1.30
1.00
.40
6
- 8 ft
3.50
2.50
1 .00
Soil Textures
Depth
Hole
Hole 2
Hole
0
- 2 ft
Sand
Sand
Sand
2
- 4 ft
Sand
Sand
Sand
4
- 6 ft
LSand
Sand
Sand
6
- 8 ft
SaLonn
LSand
Sand
Soil Radon Concentrations (pCi/L)
Sample 1
1197.0
Water Table Depth (ft)
Months Depth
6.00 6.0C
RESULTS 4
I
I RESIDENTIAL SITE INCCOR RADOM POTENTIAL: €.8 pCi/L i
I This site is in a
I YST.LOW i
I radon protection category as referenced by the 1
I Florida Radon Protection Map I
+
I certify that the site and input data are correct to the best of my knowledge.
Rodger Kolt " Agent for: RAE
Figure 4-5. RAETRAD-F printout for the Hernando site.
4-6
-------
Analysis of Site Test Data for
RESIDENTIAL RADON CONTROL CATEGORY CLASSIFICATION
using RAETRAD-F v.1.1
written by-
Rogers s Associates Engineering Corporation
SITE Location: 30.1883 Deq N, 84.1914 Deq W
County: Wakulla Run Date: 4-14-1995
State: Florida Run Time: 8:12
Zipccde: User: Rodger Holt
INPUT DATA Measured by: RAE
Average Site Dry Density (g/cc): 1.676
Radium Concentrations (pc.i/g)
Depth Hole 1 Hole 2 Hole 3 Hole 4 Hole 5
0 -
2
ft
.80
.60
.30
1.30
.80
2 -
4
ft
.70
.60
.90
1.70
.90
4 -
6
ft
2.00
1.10
.50
2.10
2.40
6 -
8
ft
2.20
1.30
.90
.80
2.40
Soil Textures
Depth
Hole 1
Hole 2
Hole 3
Hole 4
Hole
0
- 2 ft
SaCLm
SaCLm
SaCly
Clay
CLoarr.
2
- 4 ft
SaCly
Clay
SaCly
Clay
Clay
4
- 6 ft
Clay
Clay
SaCly
Clay
Clay
6
- 8 ft
Clay
Clay
Clay
Clay
Clay
Soil Radon Concentrations (pCi/L)
Sample 1
15.0
Water Table Depth (ft)
Months Depth
3.00 2.00
3.00 2.00
3.00 2.00
3.00 2.00
RESULTS
RESIDENTIAL SITE INDOOR RADON POTENTIAL: 2.1 pCi/L
This site is in a
GREEN
radon protection category as referenced by the
Florida Radon Potential Map
I certify that the site and input data are correct to the best of my knowledge.
Rodger Holt Agent for: RAE
Figure 4-6. RAETRAD-F printout for the Wakulla site.
4-7
-------
Analysis of Site Test Data for
RESIDENTIAL RADON CONTROL CATEGORY CLASSIFICATION
using RAETRAD-F v.1.1
written by
Rogers & Associates Engineering Corporation
SITE Location: 30.3401 Deg N, 84.0156 Deg W
County: Jeffersor. Run Date: 4-14-1995
State: Florida Run Time: 8:08
Sipcode: User: Rodger Holt
INPUT DATA Measured by: RAE
Average Site Dry Density (g/ccl: 1.407
Radium Concent rat ions (pCi/g)
Depth
Hole 1
Hole 2
Hole 3
Hole 4
Hole b
0 - 2 ft
.30
.60
.60
.40
.50
2 - 4 ft
.70
.60
.40
.80
.60
4 - 6 ft
1.00
.60
.80
.70
.30
6 - 8 ft
.90
.80
.80
.80
.60
Soil Texfj
res
Depth
Hole 1
Hole 2
Hole 3
Hole 4
Hole 5
0 - 2 ft
Sand
Sand
Sand
Sand
Sand
2 - 4 ft
Sand
Sand
Sand
Sand
Sand
4 - 6 ft
LSand
LSand
SaLom
LSand
LSand
6 - 8 ft
SaLcm
SaCly
SaLom
CLoam
SaLom
Soil Radon
Concentrations
(pCi/L)
Sample 1
91.0
Water Table Depth (ft)
Months Depth
6.00 6.00
RESIDENTIAL SITE INDOOR RADON POTENTIAL:
2.1 pCi/L
i
This site is in a
;
GRF.EN
1
radon protection category as referenced
by the
I
i
Florida Radon Protection Map
I certify that the site and Input data are correct to the best of ir.y knowledge.
Rodger Holt Agent for: RAE
Figure 4-7. RAETRAD-F printout for the Jefferson site.
4-8
-------
The potential radon concentrations and site classifications from these analyses are
presented in columns 3 and 4 of Table 4-1 for comparison with the classifications of the radon
protection maps. Both of the sites that were located in an elevated radon potential category
(as designated by the radon protection map) were determined to have a corresponding
elevated (Red) radon potential classification by the site-specific tests using the laboratory
radium assays. Two of the three sites that were mapped in the intermediate radon potential
category (Sumter-1 and Hernando) were determined to have a corresponding intermediate
(Yellow) radon potential classification by the site-specific tests using the laboratory radium
assays. The other site mapped in the intermediate radon potential category (Sumter-2) was
determined to have a low (Green) classification by the site-specific tests, but was within 8%
of the boundary between the green and yellow categories. The two sites mapped in the low
radon potential category were both determined to have a corresponding low (Green) radon
potential classification by the site-specific tests.
Table 4-1. Potential radon concentrations and site radon potential categories
from RAETRAD-F analyses.
Using Lab Radium Assays Using Borehole Gamma Logs
Site
Radon
Protection
Map
Category
Potential
Radon
Cone.
(pCi L"1)
Site Radon
Potential
Category
Potential
Radon
Cone.
(pCi L1)
Site Radon
Potential
Category
Polk-1
Red
35.2
Elevated (Red)
27.7
Elevated (Red)
Polk-2
Red
104.5
Elevated (Red)
70.4
Elevated (Red)
Sumter-1
Yellow
8.1
Intermediate (Yel.)
9.0
Elevated (Red)
Sumter-2
Yellow
3.7
Low (Green)
3.5
Low (Green)
Hernando
Yellow
6.8
Intermediate (Yel.)
13.3
Elevated (Red)
Wakulla
Green
2.1
Low (Green)
1.8°
Low (Green)
Jefferson
Green
2.1
Low (Green)
2.4
Low (Green)
"Assumes 1 pCi g'1 radium concentrations in holes where water precluded gamma ray
measurements.
4-9
-------
Corresponding separate model analyses used alternative radium distributions that were estimated from
the borehole gamma ray measurements (Table 3-3) instead of the laboratory radium assays. The individual
RAETRAD-F printouts from these analyses are presented in the Appendix. The potential radon concentrations
and site classifications from these analyses are summarized in columns 5 and 6 of Table 4-1 for comparison
with the previous analyses and the map classifications. Both of the sites that were located in an elevated radon
potential category (as designated by the radon protection map) were again determined to have a corresponding
elevated (Red) radon potent ial classification by Ihc sile-spccific tests that used borehole gamma ray logs. Two
of the three sites that were mapped in the intermediate radon potential category (Sumter-1 and I Iernando) were
also found to have an elevated (Red) radon potential classification when the model analyses utilized the
alternative radium distributions from the borehole gamma ray logs. The other site mapped in the intermediate
radon potential category (Sumter-2) was again determined to have a low (Green) classification by the
alternative site-specific tests. The two sites mapped in the low radon potential category were both determined
to have a corresponding low (Green) radon potential classification by the alternative model analyses.
The comparisons summarized in Table 4-1 show agreement or conservative differences between the
map and site-specific analyses. The differences for the Sumter-2 site result from the conservative land
classification by the radon potential map. Although locally-elevated conditions were found for the other six
sites, this site reflects the general conservatism (95% confidence limit) of the radon potential map (Nie94;
Nic95a). The only other sites showing differences, Sumter-1 and Hernando, were correctly modeled from the
laboratory radium assays but were conservative!)' modeled by the borehole gamma ray logs. The conservatism
in the gamma ray measurements could have resulted from any of several recognized systematic sources,
including contributions from natural thorium-chain radionuclides to the radium estimates and to a lesser extent,
auger smearing of elevated-radium soils from the deepest strata into upper, low-radium soil regions around the
borehole. The differences for the Sumter-1 and Sumter-2 sites could also be attributed to random variation,
since they are within approximately 8-12% of the respective 8.3 pCi L"' and 4.0 pCi L 1 map category cut
points.
4-10
-------
The sites selected for this study showed good correspondence between the detailed field tests and the
map predictions. The measurements and analyses comprise an acceptable benchmark between measured and
mapped radon potentials. It should be noted that the potential radon concentrations printed in Figures 4-1
through 4-7, in the Appendix, and in Table 4-1 are 95% confidence limit values, as described in section 2.1.7,
and should not be confused with median or most likely site radon levels.
The simplified alternative protocol for site radium estimates proved to give generally equivalent or
conservative results. Although the simpler method gave faster results at lower cost, it was potentially less
accurate because of the added uncertainty in calibrating gamma ray intensity to soil radium concentration. The
potential errors were conservative, however, because the potentially-increased rad ium variations served to raise
the 95% confidence limits of potential radon concentration calculated by RAETRAD-F. The alternative
protocol was also conservative because thorium-chain gamma rays increased the total radium estimate from
gamma radiation, even though the thorium-chain radionuclides do not produce "^Rn.
4.2 GKNKRALTZEI) MODEL-MAP C OMPARISONS
A second, more generalized comparison was also made between RAETRAD-F calculations and the
data plotted on the state-wide radon protection map. This comparison addressed each of the 3,919 polygons
except those controlled by lakes or other surface water, but it relied on generic data rather than site-specific
measurements for input to the RAETRAD-F code.
The basis of the generalized model-map comparisons was the state-wide polygon definitions of soil
radium concentrations. The radium distributions computed for each map polygon from National Uranium
Resource Evaluation (N'URE) aeroradiometric data were first plotted in terms of the geometric mean versus
the geometric standard deviation for each polygon. Polygons mapped in the red (elevated radon potential)
category were plotted with circles; polygons mapped in the yellow (intermdediate radon potential) category
were plotted with triangles; and polygons mapped in the green (low radon potential) category were plotted
4-11
-------
with small dots. The resulting scatter plot, shown in Figure 4-8, shows distinct grouping that
corresponds to map categories.
For comparison with EAETRAD-F, calculations were performed to estimate where the
green-yellow and yellow-red cut points would fall on the scatter plot. For the RAETRAD-F
calculations, all soils were represented conservatively by sand. This coarse texture provided
maximum permeability and diffusivity and minimal water retention, thus permitting as much
surface radon release as possible. Soil radon concentrations were defined to be small (10 pCi
L"1) to avoid RAETRAD-F adjustments for deeply-buried elevated-radium layers. Water
tables were defined to have a minimum depth of 3 m (10 ft) for a duration of 3 months. Soil
radium distributions were defined to be log-normal with geometric means and geometric
standard deviations (GSD) that were varied to fall into different map categories. For each
of fifteen RAETRAD-F calculations, 20 log-normal radium concentrations with the desired
geometric mean and GSD were computed. GSDs of 1.05, 2, 3, 4, and 5 were used with
geometric means of 0.4, 1, and 3 pCi g"1. From the computed values of C95 for each GSD,
corresponding C95 values were interpolated at the 4 pCi L"1 (green-yellow) and 8.3 pCi L"1
(yellow-red) map cut points.
The resulting cut point lines separating the color categories of the radon protection
map were plotted on Figure 4-8 for comparison with the individual points representing each
map polygon. As expected, the map data points are generally clustered by color category,
with occasional outliers caused by high water tables (positive outliers) or elevated geologic
radium sources (negative outliers). The lines calculated generically by RAETRAD-F have
approximately correct shapes and spacing, but are shifted to the left of where they would
provide an ideal fit. This difference in GSD is expected, since the maps utilize large-area
regional GSDs that are dominated by aeroradiometric and soil variations, while the
RAETRAD-F analyses utilize GSDs controlled by radium and moisture variations over a 1-
acre site.
4-12
-------
Jjjj III i ; t » i i |»ii» f i > i < | i i i i ) i i i i | i » i i [ i i i
0
o
o
° Red polygons
* Yellow polygons
• Green polygons
— Yellow-red cut points
Green-yellow cut points
123456789
Geometric standard deviation of radium concentrations
Figure 4-8. Comparison of radon protection map and RAETRAD-F data domains.
4-13
-------
As suggested by Figure 4-8, the generic map data have GSDs about 0.5 greater than
the site-specific data. Thus, an increase of 0.5 in the site-specific GSDs would improve their
correspondence with the regional GSDs plotted on the radon protection map. Although it is
reasonable to expect that a site-specific GSD is smaller than the regional GSDs, there is
presently no theoretical basis to estimate how much larger the regional variations may be.
An example plot, shown in Figure 4-9, shows that the increase of only 0.5 in the site-specific
GSD gives good agreement with the primary clusters of yellow-polygon data that separate
the green and red data domains.
0 I r i i | i i i i | i ii i |
O)
8
3
c
o
"5
k_
c
-------
4.3
SUMMARY OF MODEL-MAP COMPARISONS
Site-specific measurements using the measurement and analysis methods prescribed by the original
site characterization protocol (Nie96) gave identical radon protection categories to those shown on the radon
protection map at six of the seven sites that were tested. At the remaining site, the potential radon
concentration (C95=3.7 pCi L'1) was slightly below the map cut point of 4 pCi L'1 that would have placed it into
an equivalent category. The conservative display by the map is expected, since the map categories are defined
to contain significant areas with lower radon potentials.
Slightly more conservative site categories were obtained using the alternative protocol that replaces
laboratory radium assays with field borehole gamma-ray logs. Although all of the sites mapped with low or
elevated classifications retained the same category under the alternative protocol, two of the intermediate-class
sites were indicated as elevated. This conservatism could potentially be eliminated by alternative calibrations
or field instruments that reduce 23"Th-chain radionuclide interference.
On a broader scale, less-specific comparisons of the radon protection map with the site-specific data
analysis model (RAETRAD-F) also show consistency. This comparison is complicated by an inherent
difference in scale between regional variations (for areas averaging 8,800 acres) and localized variations (for
sites of I acre or less). Nevertheless, this comparison suggests that even the complete state-wide distribution
of radon potentials i.s consistent with the trends shown by the RAETRAD-F model, which is prescribed for
analyzing site-specific measurement data.
4-15
-------
5. LITERATURE REFERENCES
DCA94 Florida Department of Community Affairs, Florida Standard for Radon-Resistant Residential
Building Construction, Tallahassee FL: Florida Department of Community Affairs, proposed Rule
9B-52, amended December 1994.
DCA95 Florida Department of Community Affairs, Florida Standard for Passive Radon-Resistant New
Residential Building Construction. Tallahassee, FL: Florida Department of Community Affairs,
Radon Program, July 1. 1995.
EPA92a U.S. Environmental Protection Agency, A Citizen's Guide to Radon, second edition, Washington,
DC: U.S. Environmental Protection Agency report ANR-464. May 1992.
EPA92b U.S. Environmental Protection Agency, Technical Support Document for the 1992 Citizen's Guide
to Radon. Washington D.C.: U.S. Environmental Protection Agency report EPA-400-R-92-011
(MIS PB92-218395), May 1992.
Nie94 Nielson, K.K., Holt, R.B., and Rogers, V.C., Residential Radon Resistant Construction Feature
Selection System, Research Triangle Park, NC: U.S. Environmental Protection Agency report
EFA-600/R-96-005 (NTIS PB96-153473), February 1996.
Nie95a Nielson, K.K.. Holt, R.B., and Rogers, V.C., Statewide Mapping of Florida Soil Radon Potentials,
Volumes 1 and 2. Research Triangle Park, NC: U.S. Environmental Protection Agency report
EPA-60Q/R-95-142(a,b) (NTISPB96-104351 and 104369), September 1995.
Nie95b Nielson. K.K., Lund, D.M., Rogers, V.C... Rogers, B.C., and Holt, R.B., Preferential Radon
Transport through Permeable Channels in Soils, Salt Lake City, UT: Rogers & Associates
Engineering Corporation report RAE-941H/1-6, June 1995.
Nie96 Nielson, K.K., Rogers, V.C., and Holt, R.B., Site-Specific Protocol for Measuring Soil Radon
Potentials For Florida Houses, Research Triangle Park, NC: U. S. Environmental Protection
Agency report EPA-600/R-96-045 (NTIS PB96-175260), April 1996.
5-1
-------
Rog95
Rogers, V., Rogers, V.C., and Nielson, K.K., RAETRAD-F: User's Guide for Analyzing Site-
Specific Measurements of Soil Radon Potential Category for Florida Houses. Salt Lake City, UT:
Rogers & Associates Engineering Corp. report RAE-9226/7-2R1, May 1996.
SCS75 Soil Conservation Service, Soil Taxonomy, A Basic System of Soil Classification for Making and
Interpreting Soil Surveys, Washington D.C.: U.S. Department of Agriculture, Soil Conservation
Service. Agriculture Handbook No. 436, 1975.
SCS91 Soil Conservation Service, State Soil Geographic Data Base (STATSGO) Data Users Guide,
Lincoln, Nebraska: National Soil Survey Center, Soil Conservation Service, U. S. Department of
Agriculture, draft report, 84pp, 1991.
Tlio79 Thomas, J. W. and Countess, R.J., Continuous Radon Monitor, Health Physics 36, 734-738, 1979.
Tho85 Thomas, B.F., Cummings, E., and Wittstruck, W.H., Soil Survey of Alachua County Florida.
Gainesville, FL: U.S. Department of Agriculture, Soil Conservation Service. 1985.
Wi 191 Williamson, A.D. and Finkel, J.M., Standard Measurement Protocols. Florida Radon Research
Program, Research Triangle Park, NC: U.S. Environmental Protection Agency report EPA-600/8-
91-212 (NTIS PB92-115294), November 1991.
5-2
-------
Appendix
RAETRAD-F Analyses
Using Borehole Gamma Ray Estimates of Radium Concentrations
Analysis of Site Test Data for
RESIDENTIAL RADON CONTROL .CATEGORY CLASSIFICATION
using RAETRAD-F v.1.1
written by
Ragers i Associates Engineering Corporation
SITE Location: 27.89-56 Deg N, 81 .8653 Deg W
County: Polk Run Date: 10- 6-1995
State: Florida Run Time: 9:4"7
Zipcode: User: Rodger Holt
INPUT DATA Measured by: RAE
Average Site Dry Density (q/cc): 1.605
Average Site Soil Texture: Sana
Radiurr. Concentrations (pCi/g)
Depth Hole 1 Hole 2 Hole 3 Hole 4 Hole 5
0-2
ft
3 .20
3.50
4.40
3.90
5.10
2-4
ft
5.40
4 . 50
4 .00
5.10
5.30
4-6
ft
5.70
5.40
5.70
4 .70
4 .10
6-8
ft
4 .30
5.00
4 .00
3.50
3.40
Soil Radon Concentrations (pCi/L)
Sample 1 Sanple 2
16CC.0 2978.0
Water Table Depth (ft)
Months Depth
3.CO 5.00
RESULTS
RESIDENTIAL SITE INDOOR RADON POTENTIAL: 27.7 pCi/L
This site is in a
RED
radon protection category as referenced by the
Florida Radon Protection Map
I certify that the site and input data are correct to the best of my Knowledge.
Rodger Holt Agent for: RAE
Figure A-l. RAETRAD-F printout for the Polk-1 site.
A-l
-------
Analysis of Site Test Data for
RESIDENTIAL HADON CONTROL CATEGORY CLASSIFICATION
using RAETRAD-F v.1.1
written by
Rogers l Associates Engineering Corporation
SITE Location: 27.8961 Deg N, 81.8654 Deg W
County: Polk Run Date: 1C- 6-1995
State: Florida Run Time: 9:51
Zipccde: User: Rodger Holt
INPUT DATA Measured by: RAE
Aver
age Site
Dry Density (g/cc)
: 1.616
Radium Cor
icentrations (p
Ci
/g >
Depth
Hole 1
Hole
2
Hole 3
Hole 4
Hole 5
0 - 2 ft
4 .30
4 .
40
12.90
4.50
13.20
2 - 4 ft
3.10
3 _
30
11.60
4.50
13.20
4 - 6 ft
2.70
V.
10
7.50
3.30
13.10
6 - 8 ft
3 .50
c
10
4 .60
6.10
8.30
Soil Textures
Depth
Hole 1
Hole
2
Hole 3
Hole 4
Hole 5
0 - 2 ft
Sand
Sand
S a Lorn
Sana
SaLorri
2 - 4 ft
Sand
Sand
LSand
Sand
Sand
4 - 6 ft
Sand
Sand
Sand
Sand
Sand
6 - 8 ft
Sand
Sand
Sand
Sand
Sand
Soil Radon Concentrations (pCi/L)
Sample 1 Sair.ple 2
1363.:
4128.0
Water Table Depth
Months Depth
3.00
5.00
RESULTS ¦»
I i
I RESIDENTIAL SITE INDOOR RADON POTENTIAL: 70.4 PCi/L
I i
I This site is in a !
I RED i
I radon protection category as referenced by the 1
1 Florida Radon Protection Map I
I i
+ 1
I certify that the site and input data are correct to the best of my knowledge.
Rodger Holt Agent for: RAE
Figure A-2. RAETRAD-F printout for the Polk-2 site.
A-2
-------
Analysis cf Site Vest Data for
RESIDENTIAL RADON CONTROL CATEGORY CLASSIFICATION
usinc RAETRAD-F v.1.1
written by
Rogers £ Associates Engineering Corporation
SITE Location: 28.8808 Deg N, 82.0873 Deg W
County: Sumter Run Date: 10- 6-1995
State: Florida Run Time: 9:54
Zipcode: User: Rodger Holt
INPUT DATA Measured by: RAF,
Average Site Dry Density
-------
Analysis of Site Test Data for
RESIDENTIAL RADCN CONTROL CATEGORY CLASSIFICATION
using RAETRAD-F v.1.1
written by
Rogers & Associates Engineering Corporation
SITE Location: 28.9319 Dcg N, 82.1K1 Deg W
County: Sumter Run Date: 10- 6-1995
State: Florida Run Time: 9:57
Zipccde: User: Rodger Holt
INPUT DATA Measured by: RAE
Average Site Dry Density (g/cc): 1.509
Radium Concentrations (pCi/g)
Depth Kcle 1 Hole 2 Hole 3 Hole 4 Hole 5
0-2
ft
.40
.40
.40
.40
.30
2-4
ft
.40
.50
.50
.40
.40
4-6
ft
.50
1.10
.60
.50
.30
6 - ti
ft
1.70
2.60
1.50
2.00
.30
Soil Textures
Depth
Hole 1
Hole 2
Hole 3
Hole 4
Hole
0
- 2 ft
Sand
Sand
Sand
Sana
Sand
2
- 4 ft
Sa nd
Sand
Sand
Sand
Sand
4
- 6 ft
Sand
Sand
Sand
Sand
Sand
6
- 8 ft
Sand
LSand
Sand
SaLoir,
Sand
Soil Radon Concentrations (pCi/L)
Sample 1
515.0
Water Table Depth (ft)
Months Depth
6.CO 6.00
RESULTS +
; i
I RESIDENTIAL SITE INDOOR RADON POTENTIAL; 3.5 pCi/L t
I I
i This site is in a I
GREEN 1
i radon protection category as referenced by the I
I Florida Radon Protection Map |
I certify that the site and input data are correct to the best of my knowledge.
Rodger Holt Agent for: RAE
Figure A-4. RAETRAD-F printout for the Sumter-2 site.
A-4
-------
Analysis of Site Teat Data for
RESIDENTIAL RADON CONTROL CATEGORY CLASSIFICATION
using RAETRAD-F v.1.1
written by
Rogers & Associates Engineering Corporation
SITE Location: 28.5535 Dec N, 82.3022 Deg K
County: Hernando Run Date: 10- 6-1995
State: Florida Run Time: 10:00
Zipcode: User: Rodger Holt
INPUT DATA Measured by: RAE
Average Site Dry Density (g/cc): 1.433
Radium Concentrations (pCi/g)
Depth Hole 1 Hole 2 Hole 3
0-2
ft
.70
2-4
ft
1.20
4-6
ft
2.70
6-8
ft
3.40
I.00 .50
2.40 .50
3.40 .50
3.4C 1.30
Soil Textures
Depth Hole 1 Hole 2 Hole 3
0 - 2 ft Sand Sand Sand
2 - 4 ft Sand Sand Sand
4 - 6 ft LSana Sand Sand
6 - 8 ft SaLorn I.Sand Sand
Soil Radon Concentrations (pCi/L!
Sample 1
1197.0
Water Table Depth (ft)
Months Depth
6.00 6.00
RESULTS
I RESIDENTIAL SITE INDCOR RADON POTENTIAL: 13.3 pCi/L
I
I This site is in a
I RED
I radon protection category as referenced by the
I Florida Radon Protection Map
I
+
I certify that the site ar.d input data are correct to the best of my knowledge.
Rodger Holt Agent for: RAE
Figure A-5. RAETRAD-F printout for the Hernando site.
A-5
-------
Analysis of Site Test Data for
RESIDENTIAL RADOK CONTROL CATEGORY CLASSIFICATION
using RAETRAD-F v.1.1
written by
Rogers & Associates Engineering Corporation
SITE Location: 30.1883 Beg N, 84.1914 Deg W
County: Wakulla
State: Florida
Zlpcode:
Run Date: 10- 6-1995
Run Time: 10:0b
User: Rodger Holt
INPUT DATA Measured by: RAE
Average Site Dry Density (g/cc):
1 .676
Radium Concentrations (pCi/g)
Depth Hole 1 Hole 2 Hole
Hole
0 - 2 ft
2 - 4 ft
4 - 6 ft
6 - 8 ft
Depth
0 - 2 ft
2 - 4 ft
4 - 6 ft
6 - 8 ft
Sample 1
15.0
Hole
1 .CO
1.00
1.00
1 .00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1 .00
1.00
1.00
1.00
1.00
1.00
i .00
1.00
1.00
ires
Hole 1
Hole 2
Hole 3
Hole 4
Hole 5
SaCLm
SaCly
Clay
Clay
SaCLm
Clay
Clay
Clay
SaCly
SaCly
SaCly
Clay
Clay
Clay
Clay
Clay
CLoam
Clay
Clay
Clay
i Concentrations
(pCi/L)
Water Table Depth (ft)
Months Depth
3.00
2.CO
RESULTS + +
1 I
I RESIDENTIAL SITE INDOOR RADON POTENTIAL: 1.8 pCj/L I
I . I
I This site is in a I
I GREEN t
I radon protection category as referenced by the |
I Florida Radon Protection Map I
I !
+ ~
I certify that the site and input data are correct to the best of my knowledge.
Rodger Holt Agent for: RAE
Figure A-6. RAETRAD-F printout for the Wakulla site.
-------
Analysis of Sir.e Test Data tor
RESIDENTIAL RADON CONTROL CATEGORY CLASSIFICATION
using RAETRAD-F v.1.1
written by
Rocers & Associates Engineering Corporation
SITE Location: 30.3401 Deg N, 84.0156 Deg W
County: Jefferson Rut. Date: 10- 6-1995
State: Florida Run Time: 10:08
Zipcode: User: Rodger Holt
INPUT DATA Measured by: RAE
Average Site Dry Density (g/cc) : 1.40"?
Radiurr, Concentrations (pCi/g)
Depth Hole 1 Hole 2 Hole 3 Hole 4 Hole 5
0-2
ft
.30
.30
.30
.30
.30
2-4
ft
.50
.AO
.40
.60
.20
4-6
ft
.90
1.00
.90
1.30
.40
6-8
ft
1.00
1.20
1.10
1.40
.40
Soil Textures
Depth Hole 1 Hole 2 Hole 3 Hole 4 Hole
0 - 2 ft Sard Sand Sand Sand Sand
2 - 4 ft Sand Sand Sand Sand Sand
4 - 6 ft LSand LSand SaLom LSand LSand
6 - 9 ft SsLoni SaCly SaLorr. CLoam SaLom
Soil Radon Concentrations (pCi/1)
Sample 1
91.0
Water Table Depth (ft)
Months Depth
6.00 6.00
RESULTS + +
I I
I RESIDENTIAL SITE INDOOR RADON POTENTIAL: 2.4 od/L I
I I
I This site is in a I
I GREEN I
I radon protection category as referenced by the I
I Florida Radon Protection Map I
I I
+ +
I certify that the site and input data are correct to the best of my knowledge.
Rodger Holt Agent for: RAE
Figure A-7. RAETRAD-F printout for the Jefferson site.
A-7
------- |