United States Office of Air and Energy Engineering
Environmental Protection Research and Development Research Laboratory
Agency Washington, DC 20460 Research Triangle Park, NC 27711
EPA/600/N-94/011 August 1994
-------
Section 1: Project Highlights
Research
Electrically Induced Barriers to Soil-Gas
Movement
In the fall of 1993, RMB initiated a project to study the
feasibility of using an applied electric field to induce a barrier to
soil gas migration, in order to prevent the entry of soil-gas-
borne contaminants such as radon, pesticides, biological
agents, and organic compounds into buildings. An example of
radon prevention in new construction using this new technol-
ogy is illustrated in Figure 1. A patent application for this
process has been filed. This new technology could be less
costly than conventional methods and may be applicable in
regions of the country where the conventional methods are not
applicable. Other advantages of this potential new technology
include minimum intrusion into the living space, no noise
generation, moisture control, low capital and operating costs,
no mechanical parts to wear out, and prevention of radon
emissions to the ambient air. In addition to radon control, other
possible applications of this new technology include enhanced
performance of clay-type liners used in landfills and waste
disposal facilities including radioactive waste storage facilities.
The primary transport processes of soil gas contaminants in
the vadose zone (the zone of soil above the permanent water
table that contains both moisture and air) are advective flows
and molecular diffusion. Numerous studies have shown that
the air permeability of the soil is the most important single
D C Power
Supply
Living
Space
Grade
Level
Basement
aggregate
irain
V x
I
O D
Positive
Electrode
Negative
Negative
Electrode
Figure i. A schematic Illustrating the application of an electri-
cally Induced soil-gas barrier for new construction.
factor influencing the transport of soil-gas contaminants into
structures. Studies have also shown that the level of moisture
contained in the vadose zone has a profound influence on the
permeability and diffusivity of the soil. When the soil is fully
saturated with water, migration of contaminants (especially
radon) is very limited. In many soils, a 20% increase in
moisture will result in a 70% reduction in contaminant trans-
port. This sensitivity of transport to moisture content is ex-
ploited with this new technology.
In this new technology, an electric field is used to generate and
maintain a layer of moisture in soil, thus lowering the perme-
ability and diffusivity of the soil surrounding the substructure of
a building. An applied electric field induces movement of water
in soil because the water contains ions (usually positive) that
have been released into solution by the soil particles. When
these ions move under the action to the electric field, they tend
to drag the water droplets along with them. This results in
motion of water toward the cathode {negative electrode).
When sufficient water has been moved toward the cathode, a
zone depleted of water develops near the anode. As this
depleted zone develops, the current will decrease because
fewer charge carriers are available near the anode. In an ideal
case, the current would go to zero while the static field
maintains a layer of high moisture content near the cathode.
Under these ideal conditions, no electrical energy would be
required to sustain the layer that forms a barrier to the move-
ment of soil contaminants (Figure 1).
Preliminary studies using small columns of soil indicated sig-
nificant progress in developing a blocking barrier in five differ-
ent soils ranging from sand to clay. As an example, the results
for a loamy sand are described briefly. Figure 2 shows the
current in the soil as a function of time for an applied potential
of 31 volts (10 volts or less may be adequate). Note that the
current decreases rapidly as the zone near the anode is
depleted of water. After more than a month, the voltage was
doubled to 62 volts. The current initially doubled, but slowly
decreased to about the previous value. Figure 3 shows the
measured permeability as a function of time. Note that the
permeability portrays a similar behavior to the current in that it
decreases with time indicating an increase in the moisture
content in the region near the cathode. After about a week, the
permeability began to increase very slowly with time. The
cause of this behavior is not currently understood. While the
measurements to date are preliminary, all five soils tested
showed similar behavior indicating that a barrier to soil gas
movement can be Induced by the application of a DC voltage.
Progress in these studies will be reported in a future Update.
(Ronald Mosley, 919/541-7865)
US FP*
Headouprters and Gris^Cc braries
t a WestBldg Room 3340
Mailcode 3404T
1;". avp tyyy
Vw>{»}(j4
I 2u2-oe.c. oLod
-------
3
Loamy Sand - 20 cm Between Grids
2.4
1.8
1.2
31 V DC Applied
62 V DC Applied
0.6
T
T
T
4-
T
12/27/93 01/06/94 01/16/94 01/26/94 02/05/94 02/15/94 02/25/94 03/07/94
Figure 2. Current passing through the soil as a function of time.
Loamy Sand - 20 cm Between Grids
1.2E-07
1E-07
8E-07
6E-07.
4E-07
2E-07 ,
45.0% Initial Saturation
1.62g/cm 3 Bulk Density
mfrurn*
31 V DC Applied
T
T
62 V DC Applied
12/27/93 01/06/94 01/16/94 01/26/94
Figure 3. Measured permeability of the soli as a function of time.
3
02/05/94
I
02/15/94
I
02/25/94
03/07794
-------
Studies of Radon Movement Through Soil and
Building Foundations
Because indoor radon constitutes a serious health threat in
many buildings and homes throughout the country, a better
understanding is needed of the ways in which the properties of
soils and building structures influence indoor radon levels.
Many studies of indoor radon levels have been performed in
occupied houses with few definitive conclusions about the
mechanisms of radon entry. Real houses are often too com-
plex to allow controlled experiments to study the influences of
construction detail on the entry rate of radon. While several
studies have been performed in small structures in different
sections of the country, these structures have been located in
the ambient environment and, consequently, suffer many of
the same limitations as real houses when studying the mecha-
nisms of radon production, transport, and entry. Because it is
very difficult to perform controlled experiments in occupied
buildings, and because it is impossible to control the weather
conditions that can strongly influence indoor radon levels,
RMB has constructed an indoor soil chamber.
The objectives of this project were to construct a chamber that
would be representative of real world dimensions while main-
taining the ability to perform controlled experiments. The 2-m-
tall chamber has a width of 2 m and a length of 4 m. It contains
16 m3 of radium-rich soil with a mass of about 26,000 kg. For
the first series of studies, a porous hollow cylinder is posi-
tioned in the soil with its axis parallel to the surface of the soil
and perpendicular to the length of the chamber. When the
cavity is depressurized relative to its surroundings, air entering
through the plane of the surface flows into the cavity. This
geometry has the advantage that the pressure distribution and
the resulting advective flows may be computed in closed form
provided the cylindrical cavity can be treated as if it were
infinite in length. While the chamber is clearly not infinite in
dimensions, the measurements can be arranged to simulate
infinite extent in the axial direction of the cylinder. This is
accomplished by separating the cylinder into three segments
as shown in Figure 4. While all three segments are maintained
at the same level of depressurization, the three resulting flows
are measured separately. This arrangement is analogous to
using "guard" ends in an electrical measurement of voltage
and current. The guard ends serve to isolate the center section
of the cylinder from the edge effects that occur near the ends,
thus allowing the center section to measure flows that are
undisturbed as if the cylinder were infinite. All the extended
measurements except moisture are performed in the vertical
plane passing through the center of the chamber. These
probes provide measurements of temperature, pressure, ra-
don concentration, and tracer gas concentration at 23 loca-
tions in the central plane. A schematic of the chamber is
shown in Figure 5. While the other two dimensions are also
finite, the solution can be modified to account for these finite
dimensions. Therefore, to the extent that the guard ends work,
the advective flow in this finite chamber can be described with
analytic solutions. These analytic solutions are very helpful in
understanding the results. When diffusion is important, nu-
merical solutions are required.
Slotted Pipe
Pump
Pump
Metering
Valve
Flow
Controller
Pressure
Sensor
Pressure
Sensor
Metering
Valve
Flow
Controller
Figure 4. A schematic of the central collection tube with
"guard" ends to eliminate edge effects.
4
-------
Suction
4_ «w' Tubes
Recirculation
Probes
Figure 5. A schematic showing the soil chamber with the suction tubes and selected sampling probes (not to scale).
Because moisture in the soil pores has such an important
influence on radon production and transport, a great deal of
time has been spent characterizing these effects. Typical
moisture profiles measured at four different locations within
the chamber range from 0% at the surface exposed to air to
saturation near the bottom of the chamber where the water
table is maintained. Permeability computed using a popular
empirical model agrees reasonably well with measurements at
the probe locations within the chamber. The permeability is
quite constant until the moisture reaches about 20% of satura-
tion, then it decreases very rapidly with increasing moisture.
Calculated pressure contours in the measurement plane are
illustrated in Figure 6. Because of Ihe finite dimensions of the
chamber, the contours are not circular as they would be for an
infinite soil. The corresponding flow streamlines are shown in
Figure 7. Once again, the curves reflect the restrictions that
the sides of the chamber impose on the air flow. A comparison
between computed and measured pressures is shown in
Figure 8. The pressure distribution in the horizontal direction is
shown at five different vertical levels. Each vertical level was
chosen to correspond to a row of measurement probes in the
chamber. The center row contains the suction tube where the
greatest pressure variations occur. Calculations are repre-
sented by the curves, while measurements are indicated by
symbols. As might be expected, the pressure decreases more
quickly toward the open surface. The agreement of measure-
ments with calculations is within 14% except for a few loca-
Porous
Cylinder
Length
Figures. Dlmenslonless pressure contours for the soil-gas
chamber.
Length
Figure 7. Calculated streamlines (dlmenslonless) for the soli-
gas chamber. The porous hollow cylinder Is located
where the streamlines converge.
5
-------
0.2 J
0.4 -J
0.2 J
ra
Q.
0)
0.8 -J
0.4 -\
0 3 H
0.6 -I
0 3 -J
0.5
-0.5
Horizontal Distance (m)
Curves represent calculations; symbols represent measurements.
Figure 8. Pressure as a function of horizontal position at five
different depths in the soil-gas chamber.
tions near the bottom of the chamber and at the right side.
There is some evidence that the moisture at the right side may
be different from the measured profiles which were used to
compute the pressure. The closest moisture probe is about 0.8
m from the pressure measurement probes on the right side.
The disagreement near the bottom is probably caused by a
deficiency in the model by which the boundary conditions at
the bottom surface are not rigorously satisfied. This deficiency
was accepted for purposes of simplicity, since the error in
calculated pressure in that region has no real impact on total
flow rate or radon migration (the permeability in this region is
too low for significant flow to occur even at very high pres-
sures). (Ronald Mosley, 919/541-7865)
Existing House Research
Third Edition of Radon Mitigation Technical
Guidance Document Published
RMB has recently published the third edition of EPA's radon
mitigation technical guidance document. The new edition is
entitled "Radon Reduction Techniques for Existing Detached
Houses: Technical Guidance (Third Edition) for Active Soil
Depressurization Systems." Its identification number is EPA/
625/R-93/011, and it is dated October 1993.
The Third Edition represents a significant updating and up-
grading of the Second Edition (EPA/625/5-87/019), which was
published in January 1988. The new edition addresses prima-
rily active soil depressurization (ASD) techniques, because
these techniques are so widely used, and because they are
the techniques for which the most new information has be-
come available since the Second Edition was published. For
other mitigation techniques (e.g., house ventilation, sealing,
and basement pressurization), the user is still referred to the
Second Edition. (There is, however, fairly substantial coverage
of sealing in the Third Edition, as it applies to ASD systems.)
The ASD techniques covered in the document include subslab
depressurization, drain-tile depressurization, block-wall de-
pressurization, and sub-membrane depressurization. The docu-
ment also covers passive soil depressurization techniques and
active soil pressurization techniques.
This new edition is intended as a comprehensive and definitive
reference document. It presents far more detailed, field-oriented
information on diagnostic procedures and on ASD design,
installation, operation/maintenance, and installation/operating
costs. It addresses the full range of regional construction
characteristics, mitigation practices, and geological conditions.
During its preparation, the Third Edition was thoroughly re-
viewed by a number of mitigators from all regions of the
country, and by a wide variety of other individuals, to ensure
that it rigorously and realistically reflects field experience.
The document can be obtained from:
ORD Publications Office
Center for Environmental Research Information
U. S. Environmental Protection Agency
26 West Martin Luther King Dr.
Cincinnati, OH 45268-1072
Requests should indicate the name and EPA number of the
document, as cited in the first paragraph of this article. Copies
will be provided free of charge as long as supplies last.
(D. Bruce Henschel, 919/541-4112)
Tracer Gas Studies Confirm that
Re-Entrainment of ASD Exhausts Is Reduced
by Discharge Above the Eave
EPA's Radon Mitigation Standards (EPA/402/R-93-078) re-
quire that the exhaust gases from residential ASD systems be
discharged above the eave of the house. This requirement is
intended to reduce the exposure of persons inside the house
by reducing exhaust re-entrainment, and the exposure of
persons outdoors by improving exhaust dispersion.
Two tracer gas studies have been completed in an effort to
quantify the benefits of roof-level exhaust compared to
grade-level exhaust. One study, conducted at Colorado State
University, tested outdoor dispersion of exhausts around model
houses in a wind tunnel. The second study, conducted at
Pennsylvania State University, involved field measurements of
re-entrainment and dispersion around one house in Pennsyl-
vania.
The field re-entrainment testing in Pennsylvania indicated that
exhaust discharged upward about 0.6 m above the eave
(simulating an outdoor exhaust stack) resulted in statistically
significant reductions in re-entrainment compared to grade-level
exhaust (discharged horizontal to grade, 0.75 m above grade,
aimed directly away from the house). Specifically, indoor ra-
don concentrations resulting from re-entrainment into the base-
ment were 9 times higher with the grade-level exhaust; con-
centrations on the second story were 3 times higher. Assum-
ing a fairly high exhaust concentration of 1,000 pCi/L, in no
6
-------
case did the eave exhaust contribute indoor levels greater
than the national average natural outdoor level (0.4 pCi/L). On
average, grade-level exhaust contributed about 1.8 times the
national ambient average at that exhaust concentration; how-
ever, if an exhaust of only 100 pCi/L were assumed, this
grade-level contribution would fall to only 0.18 times the ambi-
ent average.
The wind tunnel dispersion data showed that, over a range of
wind directions, wind speeds, house heights, and roof pitches,
grade-level exhaust contributed average outdoor concentra-
tions against the exhaust side of the house that were about 7
times higher than those contributed by eave exhaust (simulat-
ing the outdoor stack), and about 25 to 50 times higher than
those contributed by exhaust midway up the roof slope (simu-
lating an indoor stack). Mid-roof exhaust always results in
outdoor concentrations statistically lower than the other two
configurations; eave exhaust almost always results in concen-
tration lower than grade-level exhaust, except when the ex-
haust is on the upwind side of the house. With mid-roof
exhaust, concentrations against the side of the house and
downwind always appear to be below the ambient average of
0.4 pCi/L; eave exhausts sometimes approach or slightly
exceed the ambient average, and grade-level exhausts often
equal or significantly exceed the ambient average. (D. Bruce
Henschel, 919/541-4112)
Selection and Design of Radon Reduction
Systems for Crawl-Space Houses
Testing has been completed on a 12 by 8.5 m crawl-space test
house at Florida A&M/Florida State University. Data reduction
is underway. The objective of this project is to optimize the
design details for crawl-space depressurization and
sub-membrane depressurization (SMD) and to compare these
results against earlier testing of natural crawl-space ventila-
tion.
During the testing, radon concentrations were measured in the
crawl space, the living area, and the interior of the hollow-block
foundation walls. Pressure differentials were also measured at
numerous locations. Tracer gases were used to assess the
impact of the system on structure ventilation rate.
Crawl-space depressurization was tested as a function of the
fan exhaust rate and of the leakage area between the crawl
space and the living area overhead. Even with the crawl-space
foundation vents closed, the exhaust fanexhausting 19 to 94
L/s (40 to 200 cfm)was unable to depressurize the crawl
space relative to the living area, regardless of floor leakage
area. Blower door tests indicated that an exhaust rate of about
940 L/s would have been required to create such depressur-
ization, due to the leakiness of the perimeter foundation walls.
Thus, a fair test of crawl-space depressurization was not
possible.
The test matrix for SMD was designed to determine the effects
of the following variables on SMD performance:
The means for distributing suction beneath the mem-
brane, including one and two individual pipes penetrat-
ing the membrane with no sub-membrane perforated
piping; a straight length of sub-membrane piping ex-
tending down the center of the crawl space; and a loop
of sub-membrane piping extending around the perim-
eter.
The degree of membrane sealing, including complete
sealing of the membrane versus sealing only around
the pipe penetration.
The SMD fan exhaust rate.
The leakage area between the crawl space and the
living area.
The SMD testing effort has just been completed and the
results and recommendations will be presented in a future
issue. (D. Bruce Henschel, 919/541-4112)
New House Construction Research
Evaluation and Demonstration of Passive
Barriers for Radon Resistant Residential
Construction
The Interagency Florida Radon Research Program has under-
taken 2 years of intensive evaluation and demonstration stud-
ies of new radon-resistant construction in approximately 80
Florida houses. RMB has been involved in the last phase of
the demonstration program which has focused on the evalua-
tion and demonstration of passive barrier controls for radon
resistant construction in about 30 houses. A concurrent study
was conducted at the University of Florida.
Preliminary results of the EPA Study indicate that passive
barriers provide significant resistances to radon entry with
indoor radon concentrations averaging 4.0 x 10^ that of sub-
slab radon concentrations. For comparison, early mitigation
investigations in existing Florida houses and elsewhere in the
nation indicated indoor-to-subslab concentration ratios typi-
cally in the 102 to 10 3 range. The new house passive construc-
tion techniques that have produced this enhanced resistance
include (1) the construction of monolithic and slab-in-stem-wall
slab-on-grade foundations, (2) care in the formulation and
placement of the concrete slab, (3) closing of construction and
utility penetrations of the slab, and (4) ensuring properly
installed and balanced heating and air conditioning systems.
The RMB study in Florida began with an assessment of
diagnostic measurement procedures for evaluating building
features and performance, development of a Builder's Agree-
ment, and identification of high radon potential construction
sites. Field activities consisted of observation and documenta-
tion of construction practices followed by conducting perfor-
mance tests of the radon resistant construction features. The
RMB Study, when completed, will report the findings and
analysis for an additional 14 new houses built by eight builders
using new construction guidance developed for Florida type
slab-on-grade houses. Tables 1 and 2 summarize the site and
house characteristics for the RMB Study houses. The tables
show that all the sites are confirmed high radon potential sites
with greater than 1000 pCi/L radon in soil gas and with typical
Florida soil permeabilities of 10 " to 10'2 m2. Typical house
areas range from around 150 to 250 m2 in area and are
characterized by relatively low natural infiltration rates of around
0.16 air changes per hour (ach).
Preliminary results indicate that the RMB Study houses with
passive radon resistant construction features are effective in
reducing radon entry into the indoor environment. Table 3
summarizes available performance data, as measured by
indoor radon, under varied air handler operation. The data in
Table 3 give a preliminary indication that indoor radon concen-
trations in houses built in radon-prone areas in accordance
7
-------
Table 1. EPA Study House Site Characteristics
Radon Flux
Through Soil Gas
House
ID
Soil Gas Screening
Concentrations (pCi/L)
Fill
(pCi/m2s)
Permeability
(cm2)
F-01
5508±72,
49821624
1.1101
1.1 (±0.4)E-11
F-02
1481±92,
15021152
a
8.8(10.8)E-12
F-03
2626±12,
23671455
4.811.3
8.4(10.8)E-12
F-04
51851389
6.110.9
2.2(10.1)E-12
F-05
19,894±60,
2706b
1.410.2
3.0(10.6)E-13
F-06
3049185,
37611389
3.010.7
6.4(11,4)E-12
F-07
2692125,
53221288
1.210.2
2.4(10.7)E-11
F-08
1308110,
30211486
1.1(10.2)E-11
F-09
14,324198,
F-10
2927139,
3.1c E-12
F-11
1.110.3
F-12
570018,
36941523
1.010.4
5.0(11.0)E-12
F-13
5989160,
37821366
9.8(10.6)E-12
a Indicates that the data are not available or not yet analyzed.
b Insufficient air flow for a good sample.
0 Insufficient data to calculate error.
Indicates no data.
Table 2. EPA Study House Characteristics
House
ID
Builder
ID
Base
Area
(m2)
Slab
Edge
Detail
Natural
Infiltration
Rate
(ach)
F-01
S-01
285
MSa
F-02
S-02
240
SSWa
0.1610.02
F-03
S-01
281
SSW
0.1710.01
F-04
S-03
182
MS
F-05
S-04
215
MS
0.1610.01
F-06
S-05
170
MS
0.1610.02
F-07
S-01
339
PTMS-
F-08
S-06
343
SSW
F-09
S-01
81c
MS
F-10
S-07
220
SSW
F-11
S-07
268
SSW
F-12
S-08
151
MS
0.1510.01
F-13
S-08
167
MS
F-14
S-07
196
SSW
a Monolithic slab (MS), slab-in-stem wall (SSW), post-tensioned monolithic slab (PTMS).
b Indicates that the data are not available or not yet analyzed.
c House F-09 is a 2-story house with a house volume comparable to other study houses.
8
-------
with Florida's radon passive radon resistant construction guid-
ance can maintain indoor radon levels below 4 pCi/L. Figure 9
provides a typical time series graph of indoor radon for one of
the houses. These results indicate that, even in the best indoor
radon reduction circumstances, diurnal and other time series
fluctuations will not be eliminated with passive control ap-
proaches.
Field assessments will be completed in 1994 and statistical
and correlational analyses of data including indoor radon
measurements, infiltration and ventilation measurements,
slab cracking measurements, radon entry rate and velocity
estimates, and other data with experimental conditions will
follow. A final EPA report should be available in late 1994.
(David Sanchez, 919/541-2979)
Table 3. Indoor Radon (CJ Under Various Air Handler (A/H) Operations
A/H Off,
O
O
A/H On,
DO
A/H On,
DC"
House
ID
Ventb
(ach)
Cinc
v
(pCi/L)
Vent
(ach)
Cin
-O
3
O
Vent
(ach)
ciB
Cou|
(PCi/L)
c.b
F-01
1.6
0.2
4312
0.9
0.2
4893
0.9
0.2
4510
F-02
0.17
1.6
1.1
886
0.17
1.6
1.2
946
0.13
0.9
0.3
753
F-03
0.17
3.8
0.4
5993
0.17
2.1
0.7
5905
0.16
1.9
1.0
6971
F-04
4.1
1.1
12,121
4.6
0.9
12,017
4.9
0.9
11,783
F-05
0.17
1.5
0.1
4490
0.17
1.5
0.6
4423
0.15
0.
0.1
4315
F-06
0.16
1.6
0.8
4524
0.17
2.7
0.7
4713
0.17
1.9
1.1
4636
F-07
0.9
0.2
4275
0.8
0.2
1.1
0.2
F-08
3.3
0.4
4004
3.1
0.6
4235
3.0
0.5
4390
F-10
F-12
0.15
1.0
2.7
0.4
6478
0.16
2.6
0.2
7816
0.14
2.3
0.1
5865
F-13
2.5
1.1
6208
2.5
0.2
5639
1.5
0.4
5725
F-14
3.1
1.1
2.4
1.1
2.1
1.1
Mean
0.16
2.3
0.6
5329
0.17
2.3
0.6
5627
0.15
1.9
0.5
5439
±S.D.
±0.01
±2.2
±0.4
±2861
±0.01
±1.1
±0.4
±3004
±0.02
±1.2
±0.4
±2930
Air handler (A/H), interior doors opened (DO), and interior doors closed (DC).
House ventilation rate from blower door measurements (air changes per hour).
Inside (Cin), outdoor (Cout), and subslab (Csub) radon concentrations (picocuries per liter).
Indicates no data.
i r
11/19/93 11/20/93 11/21/93 11/22/93 11/23/93 11/24/93 11/25/93 11/26/93
Figure 9. Indoor radon concentrations In typical house over a 10-day period.
9
11/27/93 11/28/93 11/29/93 11/30/93
-------
ASTM Considers Draft Standard Method for
Permeability Testing of Concrete
In support of the Interagency Florida Radon Research Pro-
gram, a standard method for the laboratory permeability test-
ing of field-cored concrete slab samples has been developed
by RMB. The method is being considered by the American
Society of Testing and Materials (ASTM) for adoption as a
standard test method. The method was developed and tested
for bias and precision using concrete compression core samples
and samples from various construction regions in Florida. The
method continues to be used in Florida for assessing the
quality of new and existing residential and commercial con-
crete slabs. (David Sanchez, 919/541-2979)
Schools and Other Large Buildings Research
Follow-up Radon Measurements In 14
Mitigated Schools
RMB has conducted radon mitigation research in nearly 50
public schools since 1987. ASD systems have been installed
in many of these schools researched by RMB. After mitigation,
radon levels were measured to determine the effectiveness of
the mitigation system. If the post-mitigation measurement
indicated that radon levels were still above the EPA action
level of 4 pCi/L, the mitigation system was modified, and radon
levels were remeasured.
To determine the long-term performance of these mitigation
systems, follow-up radon measurements were conducted in
14 of the schools that were mitigated between 1988 and 1991.
These follow-up measurements were made between February
and April 1992 in schools located in Kentucky, Maryland, New
York, North Carolina, Tennessee, and Virginia. The measure-
ments were made with alpha track detectors (ATDs) which
were mailed to the schools along with placement and retrieval
instructions. For quality assurance, 102 ATDs were set aside
for exposure, as spikes, with EPA's National Air and Radiation
Environmental Laboratory.
The results from these follow-up ATD measurements (Table 4)
indicate that, overall, ASD systems have been very effective in
maintaining low radon levels in the long-term in the 14 schools
that were measured for this study. Of the 409 locations mea-
sured in these schools, only 17 (or 4%) of the measurements
in mitigated areas exceeded 4 pCi/L. Eight of these 17 mea-
surements were in a basement, one was in a room where the
ASD fan had been turned off, and another was in a room with
building pressurization that is operated only while the building
is occupied. If these 10 measurements are dropped from the
set, the percent of rooms above 4 pCi/L drops to less than 2%.
(Kelly Leovic, 919/541-7717)
EPA Initiates Drafting of Standards for Large
Buildings
RMB, as part of ongoing research activities in the Florida
Radon Research Program, has begun efforts to draft prelimi-
nary radon resistant construction standards for new large
buildings in radon-prone areas of Florida. The new standard
will apply to buildings that are non-residential and have at least
930 m2 of soil contact. The preliminary draft, or "working
standard," is being assembled to address (1) passive barriers,
(2) ASD, and (3) heating, ventilating, and air-conditioning
(HVAC) system design. The "working standard" will integrate
radon and building science research, and will include findings
from residential studies, recent EPA studies of large buildings,
and good engineering practice. The objective is to establish a
consensus for the preliminary standard and prove its validity in
large buildings by the spring of 1995. (Marc Menetrez, 919/
541-7981 and David Sanchez, 919/541-2979)
Table 4. Summary of Long-Term ATD Measurements In 14 Mitigated Schools
School &
Number of
Measure-
ment
Locations
Average
Concentration (pCi/L)
Low
High
Total
Number of
Locations
Above 4
pCi/L
Number
of Locations
Above 4
pCi/L in
Mitigated Areas
Number of
Days
Exposed
A(29)
3.1+/-1.2
0.8
5.8
8
3
68
B(20)
0.4+/-0.05
0.4
0.6
0
0
68
C(20)
0.5+/-0.3
0.4
1.9
0
0
68
0(37)
2.0+/-2.1
0.4
11.6
3
0
66
E(27)
1.6+/-1.1
0.6
4.7
1
0
56
F(30)
1.6+/-1.4
0.5
6.2
3
0
56
0(37)
3.0+/-2.4
0.5
8.9
8
3
56
H(20)
0.7+/-0.2
0.4
1.1
0
0
69
'(30)
2.1+/-1.4
1.1
7.9
3
2
27
J(39)
2.0+/-1.7
1.3
9.4
3
0
83
K(25)
1.3+/-0.4
1.3
1.4
0
0
83
L(14)
11.3+/-5.5
0.6
20.8
11
8
62
M(46)
0.8+/-0.3
0.6
2.1
0
0
54
N(35)
6.2+/-3.5
1.2
15.6
26
2
53
10
-------
Demonstration of Radon-Resistant New
School Construction
EPA's technical guidance manual, "Radon Prevention in the
Design and Construction of Schools and Other Large Build-
ings" (EPA/625/R-92/016, January 1993) has been widely
distributed, with 8,500 copies sent to architects, school offi-
cials, state and local radiation offices, mitigators, and other
interested persons. Plans are underway for a third printing.
Based on the techniques described in the manual, RMB is
assisting in the design of ASD systems in 13 new schools
(Table 5):
Table 5. RMB Research Underway in New School Construc-
tion
Location Number of Schools
Tucson, AZ
5
Greenville, SC
4
Davis County, UT
2
Hagerstown.MD
1
Nottingham, NH
1
RMB's experience in applying the techniques described in the
manual has been favorable. For example, it has been rela-
tively easy to lay out an ASD system with the architect via
phone conversations if floor and foundation drawings are
available. Users seem pleased with the manual and, with a
little assistance, find it easy to use. Currently, this assistance is
free (see contact below). The following paragraphs describe
the specific experiences as a result of applying these tech-
niques in two Tucson schools.
The ASD systems were installed in these schools following
recommendations in the manual because the sites had el-
evated levels of uranium, and elevated radon levels were
anticipated. With construction nearing completion, pressure
field extension (PFE) was measured in each school with the
ASD systems operating. Good negative pressure was mea-
sured under all areas of the slab of both schools. All rooms will
be tested for radon this summer with the radon mitigation
systems on and off. Based on the PFE, it is expected that all
areas of both schools will be at near-ambient levels (<0.5 pCi/
L) when the ASD systems are operating.
As part of RMB's research, two innovations were tested in one
of the Tucson schools: 1) the use of a prefabricated suction pit
made of metal, and 2) elimination of the barrier effect on
subslab block walls by turning every other block (one row
below the slab) on its side, allowing the subslab soil gas to flow
through the holes in the blocks. With the use of the prefabri-
cated steel suction pit it was possible to decrease the overall
dimension of the pit to 0.9 m from 1.2 m with the same
effective surface area. The construction superintendent felt
that the prefabricated pit was a major improvement compared
to building a pit on site as shown in the manual. Turning every
other block on its side resulted in PFE effects as if the walls did
not exist. By this technique, the barrier effects of subslab walls
can be eliminated, and the subslab area will behave as if it
were post and beam construction with no subslab barriers.
This change (i.e., turning every other block on its side) was
made at no extra cost; the technique is now being further
evaluated in four additional schools. Drawings of these two
innovations are shown in Figures 10,11, and 12. (A.B. "Chick"
Craig, 919/541-2824)
1-1/2" (3.8 cm) x 18 ga.
Type B Galv. Mtl. Deck
4-(10.2 cm)
Concrete Slab
6 - #4 Rebar x 8' -0"
(2.44 m) Long E.W.
Centered Oyer Pit
Mm. of 4"
(10.2 cm)
of Aggregate
12" 30.5 cm)
I
Angle 2x2x1/4
(5x5x0.6 cm)
6" (15.2 cm)
Suction Pipe
Angle 2x2x1/4"
(5x5x0.6 cm) Cont.
T & B Around
Perimeter of Pit
t/ert. @ Ea
Comer
Expanded Metal on
All 4 Sides Welded to
Angle Supports
Poured Concrete
Base
Figure 10. Revised subslab suction pit.
11
-------
Figure 11. Every other Interior wall block is turned on its side to allow soil gas to pass through to suction pit.
CMU Wall
4" (10.2 cm)
Concrete Slab on
10 mil Vapor Barrier
Seal All Slab Joints & Pipes
Lintel Block Filled with Concrete
Coarse Aggre
ASTM #5
Turn Every Other 8x8x16" .
(20.3x20.3x40.6 cm) CMU Horiz.
So Soil Gas Can Pass Through
to Suction Pit
Footing
Figure 12. Interior concrete masonry unit (CMU) wall.
12
-------
Ventilation Research
Reducing Indoor Radon Levels with
Ventilation
EPA has studied engineering control strategies to reduce
indoor radon levels in schools and other large buildings for
many years. This research has focused on evaluating the
effectiveness of active and passive methods (such as ASD
and subslab barriers, respectively). As a mitigation strategy,
ASD and passive barriers have proven to be very effective in
reducing indoor radon levels. Another strategy that is being
evaluated for effectiveness is the use of the building HVAC
system. While ASD and architectural barriers mitigate radon
entry by altering communication between the subslab and the
interior of the building, HVAC systems rely on building pressur-
ization and dilution. A properly designed and operated HVAC
system can provide a higher pressure in the building relative to
the subslab and the outdoors and thereby prevent soil gas
entry.
Large buildings are designed with HVAC systems which fall
within four basic categories: All-Air, Air & Water, All Water, and
Unitary. Not all of these HVAC systems are good candidates
for the use of pressurization. To use this technique the building
HVAC system must have, at a minimum, the following system
characteristics:
a central air handling unit (AHU),
an outdoor air intake,
an air supply and return distribution system, and
an exhaust air system.
The above are commonly found in the All-Air type systems;
these are typically designed as constant-air-volume (CAV) and
variable-air-volume (VAV) HVAC systems. (See Figure 13: a
typical CAV or VAV system used in large buildings.) The ability
to pressurize a building or space relies primarily on bringing
more air into the building or space than is being removed. This
means that the HVAC system must be able to continuously:
control the amount of QM coming in through the building's
outdoor air intake, and
remove air from the Qs>h, in quantities that are less than
the outdoor air supplied.
Oca
^Qrel
t
Qexh
HVAC
System
Qsa *
Occupied
Space
Qexf ^
Qra
Qoa Flow, outdoor air
Qiei Flow, relief air
Qsa Flow, supply air
Qra Flow, return air
Qexh Flow, exhaust air
Qexf Flow, exfiltration air
Figure 13. All-air HVAC system.
The excess air, Qm(, sets up a higher pressure zone in the
building and indoor air exfiltrates through the building en-
velop. This constant movement of interior building air to the
outdoors acts to reduce or eliminate the infiltration of con-
taminants such as airborne soil-gas contaminants. VAV and
CAV systems can be designed to allow for this type of system
operation and control; however, the design engineer must
properly interpret the building outdoor air requirements in
order to accomplish building pressurization.
When calculating the outdoor air requirements, many HVAC
design engineers first use the ventilation rate procedure
outlined in the American Society of Heating, Refrigeration,
and Air-Conditioning Engineers (ASHRAE) Standard 62-1989,
and multiply the number of occupants by the appropriate cfm/
occupant for the specific space type under consideration.
(For ordinary office space the ventilation requirements are
7 L/s per occupant.) This quantity is then compared to the
building exhaust quantities. Exhaust in typical office space is
generally required in areas such as toilet rooms, janitorial and
maintenance closets, copy machine rooms, and employee
exercise facilities. In most typical cases where occupant
density is equal to or greater than seven occupants per 93
m2, the outdoor air quantity will exceed the exhaust quantities
at sufficient levels to permit building pressurization. However,
there may be some cases where occupant density can be as
low as two occupants per 93 m2 due primarily to intermittent
occupancy. In these cases the outdoor air quantities must be
increased beyond the minimum requirements outlined in
Standard 62-1989 in order to get the building to operate
under positive pressure. It is important for the design engi-
neer to realize that, when planning a system beyond the
minimum outdoor air requirements, additional design analy-
sis will be called for to ensure conformance with energy
conservation standards and codes such as ASHRAE Stan-
dard 90.1.
How effective is ventilation in mitigating radon? In trying to
determine the effectiveness of building pressurization for the
purpose of mitigating indoor radon levels, RMB performed
field studies in a number of occupied large buildings. All had
elevated indoor radon levels above the EPA action level of 4
pCi/L prior to the start of the study, were larger than 2300 m2,
and were equipped with All-Air VAV systems as previously
discussed. Baseline indoor radon levels were measured, the
HVAC systems were then adjusted to ensure building pres-
surization, and dataloggers were installed to record indoor
radon levels. Normally the HVAC systems were shut off after
normal working hours and were not operated on weekends.
(This is a typical energy conservation operational approach to
HVAC systems.) Figure 14 plots the continuous radon levels
as measured in five different rooms in one of the test build-
ings over the period of 1 week. These results show that:
the radon levels generally build up overnight until the
HVAC system comes on in the morning, and
once the HVAC system turns on, the levels drop
rapidly.
This plot was typical for all of the test buildings and clearly
shows that the HVAC system can assist in lowering the
indoor radon levels. However, in buildings with initial radon
levels above 15 pCi/L, seldom was the HVAC system suc-
13
-------
03/23
03/25
03/21
03/20
#5-Conf. Room
#2-Room 109
#4-Room 102
#6-Cale #7-Audiology A Outdoor Air
Figure 14. Continuous radon levels, 7 L/s outdoor air (OA)/occupant, HVAC on from 6 am to 6 pm 7 days/week, all exhaust fans off
from 3pm Friday (3/19) to 3 pm Saturday (3/20) until 7 am Monday (3/22), during weekdays (3/22-3/26) exhaust fans in
normal operation.
cessful in lowering levels below 4-5 pCi/L. Another consider-
ation is cases where the ambient outdoor radon levels are
high; in these cases, using outdoor air can be totally ineffective
in lowering indoor levels to below 4 pCi/L.
In Florida, field studies of large building HVAC systems cor-
roborated the above results: data collected in two buildings, an
office building in Deerfield Beach and a school in Bartow,
indicate that operation of the HVAC system and outdoor air
delivery (ventilation) rate to the occupied space significantly
reduces indoor radon concentrations. The HVAC systems
were typical of large building systems, with continuous opera-
tion during occupied hours and outdoor air delivery. Radon
levels were measured with the HVAC systems off, then with
the systems providing varied outdoor air rates. Compared with
the HVAC systems off, radon levels in the buildings were
reduced by 71% with the systems on and minimal delivery of
outdoor air; 71 to 86% with an outdoor air delivery of 2.4 L/s
per occupant; and 86 to 89% with an outdoor air delivery of 7
L/s per occupant (the current ASHRAE standard). The reduc-
tion of radon is attributed primarily to dilution, although at the
higher ventilation rates pressurization reduced the entry of
radon through the ground-contact floor.
Additional research on the effect of ventilation on radon levels
would help to gain more understanding, especially in the area
of wind and stack effect on building pressure differentials.
(Russell Kulp, 919/541-7980, and Marc Menetrez, 919/
541-7981)
Ventilation Workshop Identifies Areas for
Research
AEERL hosted a Ventilation and Indoor Air Quality Workshop
in September 1993. The purpose of the workshop was to
review and finalize AEERL's document "Ventilation Technol-
ogy Systems Analysis," which defines the state-of-the-art of
ventilation systems, identifies strengths and weaknesses of
systems, and suggests future ventilation research areas based
on emerging trends and industry needs. Attendees included
architects, engineers, experts in the building sciences, manu-
facturers, and operation and maintenance personnel. Results
from the workshop identified that (1) a great need exists for
basic research, beginning with the development of a basic
definition of "acceptable indoor air quality" (IAQ) that can be
measured in the field; (2) the potential to provide improved IAQ
through source management is promising, and a continued
emphasis on developing appropriate emissions data is needed;
(3) measurement techniques (i.e., reliable and affordable sen-
sors for IAQ) are needed; and (4) a need for better design
exists for improved operations and maintenance along with
ventilation system flexibility. The results of the workshop will
be used to identify future areas of ventilation research. The
proceedings from the workshop will be published by EPA in
late 1994. (Russell Kulp, 919/541-7980)
14
-------
Section 2: Publications and Additional Information
Recent RMB
Publications
This section summarizes recent publica-
tions by RMB. The source of the publica-
tion is listed with each summary. Publi-
cations with NTIS numbers are available
from the National Technical Information
Service at 5285 Port Royal Road, Spring-
field, VA 22161, 703/487-4650 or 800/
553-6847.
EPA Reports
Assessment of the Effects of Weath-
erlzation on Residential Radon Lev-
els (EPA-600/R-94-002, NTIS
PB94-141181, Jan. 1994). This report
summarizes results of two levels of
weatherization applied to 76 houses in
Maryland and the effect that it had on
indoor radon concentrations. Results in-
dicate that weatherization procedures
resulted in a 10 - 40% reduction in shell
air leakage rates with no adverse effect
on indoor radon levels. Note that weather
conditions impacted the data reliability.
Case Studies of Radon Reduction Re-
search In 13 School Buildings
(EPA-600/R-93-225, NTIS PB94-130010,
Dec. 1993). This report details AEERL
radon mitigation research in 13 school
buildings located in Colorado, Maine, Min-
nesota, Ohio, South Dakota, Tennes-
see, and Washington state. The objec-
tives of the research were to better un-
derstand the conditions under which
HVAC systems can be used for effective
radon reduction and to compare the per-
formance of HVAC system control of
radon with ASD control in the same build-
ing.
Case Studies of Radon Reduction Re-
search In Maryland, New Jersey, and
Virginia Schools (EPA-600/R-93-211,
NTIS PB94-117363, Nov. 1993). One
school in each of these states was se-
lected for this radon research project. In
two of the schools the objective was to
evaluate the potential for modification of
the school HVAC system to control ra-
don concentrations. The third school was
recently constructed with radon resistant
features, and the objective was to evalu-
ate the effectiveness of those features.
Characteristics of Florida Fill Materi-
als and Soils1990 (EPA-600/
R-94-052, Apr. 1994). This report docu-
ments results of laboratory work by the
University of Florida in support of the
Foundation Fill Data Base project of the
Foundation Fill Materials Specifications
Task Area of the Florida Radon Re-
search Program. Work included determi-
nation of radon concentrations in soil
gas samples and physical and radiologi-
cal characterization of soil/fill samples to
provide data for further use in modeling
radon production, transport, and entry.
Characteristics of School Buildings
In the U.S. (EPA-600/R-93-218, NTIS
PB94-121704, Nov. 1993). To guide
AEERL's radon mitigation research in
schools, information on the physical char-
acteristics of 100 randomly selected
schools was collected. The results show
the following: most school structures are
of slab-on-grade construction; gravel was
used as subslab fill material in approxi-
mately half of the structures; approxi-
mately 80% of the schools have either
central HVAC or unit ventilators capable
of delivering conditioned outdoor air; and
about 25% of the schools have subslab
footings extending both beneath the
classroom walls and along the corridors,
thus complicating the installation of a
subslab depressurization system.
Follow-up Radon Measurements In 14
Mitigated Schools (EPA-600/R-93-197,
NTIS PB94-114758, Oct. 1993). To de-
termine the long-term performance of
radon mitigation systems, radon mea-
surements were made between Febru-
ary and April 1992 in 14 schools that had
been mitigated between 1988 and 1991.
Results show that active soil depressur-
ization systems have been very effective
in maintaining low long-term radon lev-
els below 4 pCi/L in these 14 schools.
Laboratory Assessment of the Per-
meability and Diffusion Characteris-
tics of Florida Concretes. Phase I,
Methods Development and Testing
(EPA-600/R-94-053, NTIS
PB94-162781 .Apr. 1994). This report pre-
sents the results of the Phase I labora-
tory assessment of the permeability and
diffusion characteristics of Florida con-
cretes. (NOTE: The ability of concrete to
permit air flow under pressure (perme-
ability) and the passage of radon gas
without any pressure difference (diffusiv-
ity) has not been well determined. To
establish a standard concrete mix and
its maximum radon-resistant placement,
these parameters needed to be quanti-
fied and their relationship to concrete's
physical properties evaluated.)
Measurement of the Surface Perme-
ability of Basement Concretes
(EPA-600/R-93-169, NTIS PB93-232114,
Sept. 1993). This report details the de-
velopment and test results of a portable
permeameter used for surface perme-
ability measurements of concrete. Sur-
face permeability of concrete determines
the performance of seals between con-
crete sections, an important passive tech-
nique for preventing radon entry into new
buildings.
Soil and Fill Laboratory Support -1991
(EPA-600/R-94-064, NTIS PB94-163243,
Apr. 1994). The report provides a com-
pendium of soil characterization analy-
ses ( i.e., radium contact, permeability,
radon emanation, moisture, and soil clas-
sification) for soil samples collected by
the Florida Radon Research Program in
1991.
Supplement to Standard Measurement
Protocols, Florida Radon Research
Program (EPA-600/R-94-001, NTIS
PB94-144110, Jan. 1994). As a supple-
ment to earlier published standard proto-
cols for key measurements where data
quality is vital to the Florida Radon Re-
search Program, this report adds mea-
surement of small canister radon flux
and soil water potential to the section on
soil measurements. It also adds indoor
radon progeny measurement, radon en-
try rate estimation, and duct system leak-
age measurement to the section on build-
ing measurements.
Manuals
Radon Reduction Techniques for Ex-
isting Detached Houses: Technical
Guidance (Third Edition) for Active
Soil Depressurization Systems (EPA/
625/R-93/011, Oct. 1993). This manual
provides detailed Agency guidance re-
garding the design and installation of
ASD systems for indoor radon reduction,
including subslab depressurization,
drain-tile depressurization, block-wall de-
15
-------
pressurization, and sub-membrane de-
pressurization. Passive soil depressur-
ization and active soil pressurization tech-
niques are also addressed. The docu-
ment also addresses in detail system
operation and maintenance, system in-
stallation and operating costs, and diag-
nostic test procedures to aid in system
selection and design. It addresses the
full range of regional construction char-
acteristics, mitigation practices, and geo-
logical conditions. Copies can be ob-
tained from the source identified in the
article discussing this document on page
6.
Published Papers
Analysis of Radon Mitigation Tech-
niques Used In Existing U. S. Houses
(B. Henschel) (First International Work-
shop on Indoor Radon Remedial Action,
Rimini, Italy, June 27-July 2, 1993). This
paper reviews the full range of indoor
radon reduction options for existing
houses, including active and passive soil
depressurization, active soil pressuriza-
tion, basement and crawl-space pres-
sure adjustments, natural crawl-space
ventilation, entry route sealing, house
ventilation, and air cleaners. For each
technique, a summary is given of radon
reduction performance, costs, applica-
bility, and advantages and disadvan-
tages. This paper is expected to be pub-
lished in an upcoming issue of Radiation
Protection Dosimetry, as part of the pro-
ceedings of the Rimini workshop.
An Analytical Solution to Describe the
Pressure/Flow Relationship In EPA's
Soil-Gas Chamber (R. Mosley), (1993
Air Toxics Measurement Symposium,
Durham,NC,5/4-7/93). An analytical
model has been developed to describe
the relationship between pressure differ-
ential and flow rate in RMB's soil gas
chamber. The classic method of images
is applied to simulate the boundary con-
ditions imposed by the finite dimensions
of the chamber. The resulting influence
on constant pressure contours and the
streamlines is shown.
Comparison of Measurement Tech-
niques for Soil Permeability In EPA's
Soil-Gas Chamber (R. Mosley,
M.Menetrez, B. Harris et al.)(1993 Air
Toxics Measurement Symposium,
Durham, NC, 5/4- 7/93). Initial soil per-
meability measurements in RMB's soil
chamber yield relatively good agreement
between two methods. One method uses
a set of 23 point probes located in a
vertical plane and is similar to the stan-
dard practice of measuring in situ soil
permeabilities. The other method uses
an arrangement designed to ensure ideal
geometric flow patterns and yields a bet-
ter approximation of the effective bulk
permeability. The permeability measure-
ments are then compared to the predic-
tions of a widely used empirical model.
Comparison of Soli Permeability Mea-
surements Using Probes of Different
Sizes and Geometries (R.Mosley et
al.)(1994 Air Toxics Measurement
Symposium,Durham, NC, 5/2-6/94). This
study compares side-by-side measure-
ments of soil permeability for a number
of probes with different geometries and
relative sizes. The results are discussed
in terms of appropriate scale factors
based on geometrical differences.
Designs for New Residential HAC Sys-
tems to Achieve Radon and Other Soil
Gas Reduction (T.Dyess et al.) (Pro-
ceedings of the 1993 International Ra-
don Conference, Denver, CO, 9/20-23/
93). Residential heating and cooling
(HAC) systems can significantly impact
the pressure-driven entry of soil gas into
houses. Entry of soil gas is of concern
because it can contain contaminants such
as radon, volatile organic compounds,
pesticides, and biocontaminants. HAC
configurations that have lowered radon
entry rate in new construction, and which
could be applied to reduce the entry of
other soil gas contaminants, are pre-
sented.
Evaluation of Radon Movement
Through Soil and Foundation Sub-
structures (M.Menetrez,R. Mosley, et
al.)(1993 Air Toxics Measurement Sym-
posium, Durham, NC, 5/4-7/93). A 2x2x4
m chamber filled with radium-containing
soil is being used to study convective
and diffusive soil gas movement through
soil and foundation substructures. A per-
forated pipe vacuum line draws air (or
tracer gas) through the soil under vary-
ing moisture conditions to simulate con-
vective flow conditions. Data from the
chamber will be used to model soil per-
meability properties and radon entry con-
ditions imperative to site characteriza-
tion for soil gas source potential.
Large Building Characterization (M.
Menetrez, D. Sanchez, R. Kulp, et al.)
(1994 Air Toxics Measurement Sympo-
sium, Durham, NC, 5/2-6/94). Buildings
are characterized in this project by ex-
amining radon concentrations and IAQ
as affected by building ventilation dy-
namics. Measurements of indoor radon,
carbon dioxide, and particle concentra-
tions; temperature; humidity; indoor to
outdoor or subslab pressure differential;
ambient and subslab radon concentra-
tions; and outdoor air intake flow rates
were collected. The outdoor air intake
was adjusted from 0 to 20 cfm per per-
son in increments of 5 cfm, and exhaust
fans were controlled. Tracer gas mea-
surements were taken in all zones.
Measurement of the Effects of Mois-
ture Distribution on the Transport
Properties of Radon and Other Soil
Contaminants In EPA's Soil Chamber
(R. Mosley et al.) (1994 Air Toxics Mea-
surement Symposium,Durham, NC, 5/
2-6/94). This paper discusses measure-
ments performed in EPA's soil chamber
to investigate the effects of moisture dis-
tribution on the transport rates. SFe, used
as a tracer, served as a surrogate for a
contaminant gas. These measurements,
along with measured moisture profiles,
are used to infer the degree of uniformity
of the soil properties in the horizontal
direction within the chamber. Packing
density and radon distribution are also
discussed.
Measurements of Soil Permeability
and Pressure Fields In EPA's Soil-Gas
Chamber (R. Mosley et al.) (1993 Inter-
national Radon Conference, Denver, CO,
9/20-23/93). An analytic solution for ad-
vective flow in AEERL's soil-gas cham-
ber is presented. The solution includes
the effects of moisture dependent varia-
tions of permeability with position. Rela-
tively good agreement between the mea-
surements and model is obtained except
in the region near the water level where
the boundary conditions are not rigor-
ously satisfied.
Radon In Florida Large Building Study
(M.Menetrez, R. Kulp, et al.) (1993 Air
Toxics Measurement Symposium,
Durham, NC, 5/4-7/93). This paper ex-
amines how indoor air quality is affected
by ventilation, mixing, and leakage rates
in two research buildings. Measurements
include radon, carbon dioxide, tempera-
ture, humidity, differential pressures, out-
door air intake flow rates, and tracer gas
methods. The outdoor air intake is ad-
justed from no outdoor air to recom-
mended ASHRAE ventilation standards.
16
-------
EPA Regional Offices
NOTE: Telephone numbers shown are direct lines to Regional Radon Representatives,
except in the case of Region 5, where 800 numbers are available.
Region 1
(CT, ME, MA, NH, Rl, VT)
JFK Federal Building
Boston, MA 02203
(617) 565-3231
Region 2
(NJ, NY)
26 Federal Plaza
New York, NY 10278
(212) 264-0546
Region 3
(DE, DC, MD, PA, VA, WV)
841 Chestnut Building
Philadelphia, PA 19107
(215) 597-8326
Region 4
(AL, FL, GA, KY, MS, NC, SC, TN)
345 Courtland St. N.E.
Atlanta, GA 30365
(404) 347-3907
Region 5
(IL, IN, Ml, MN, OH, Wl)
77 West Jackson Blvd.
Chicago, IL 60604
From IN, Ml, OH, MN, and Wl:
(800) 621-8431
From IL:
(800) 572-2515
Region 6
(AR, LA, NM, OK, TX)
1445 Ross Avenue
Dallas, TX 75202
(214) 655-7550
Region 7
(IA, KS, MO, NE)
726 Minnesota Avenue
Kansas City, KS 66101
(913) 551-7260
Region 8
(CO, MT, ND, SD, UT, WY)
999 18th Street
Denver Place, Suite 500
Denver, CO 80202-2405
(303) 293-0980
Region 9
(AZ, CA, HI, NV)
75 Hawthorne Street
San Francisco, CA 94105
(415) 744-1046
Region 10
(AK, ID, OR, WA)
1200 Sixth Avenue
Seattle, WA 98101
(206) 553-7299
17
-------
State Radon Contacts
Alabama
James McNees
205/613-5391
800/582-1866
Alaska
Vacant
907/465-3019
800/478-8324
Arizona
John Stewart
602/255-4845
Arkansas
Lee Gershner
501/661-2301
California
J. David Quinton
916/324-2208
800/745-7236
Colorado
Linda Martin
303/692-3057
800/846-3986
Connecticut
Alan J. Siniscalchi
203/566-3122
Delaware
Maria Rejai
302/739-3028
800/554-4636
District of Columbia
Robert Davis
202/727-7106
Florida
N. Michael Gilley
904/488-1525
800/543-8279
Georgia
Richard Schreiber
404/657-6534
800/745-0037
Hawaii
Russell Takata
808/586-4700
Idaho
Steve West
208/334-6584
800/445-8647
Illinois
Richard Allen
217/786-7127
800/325-1245
Indiana
Michele Starkey
317/633-8563
800/272-9723
Iowa
Donald A. Flater
515/242-5992
800/383-5992
Kansas
Harold Spiker
913/296-1561
Kentucky
Jeana Fleitz
502/564-3700
Louisiana
Matt Schlenker
504/925-7042
800/256-2494
Maine
Bob Stilwell
207/287-5676
800/232-0842
Maryland
Leon J. Rachuba
410/631-3301
800/872-3666
Massachusetts
William J. Bell
413/586-7525
800/445-1255
Michigan
Sue Hendershott
517/335-8194
Minnesota
Laura Oatman
612/627-5014
800/798-9050
Mississippi
Silas Anderson
i601/354-6657
800/626-7739
Missouri
Gary McNutt
314/751-6083
800/669-7236
Montana
Adrian C. Howe
406/444-3671
Nebraska
Joseph Milone
402/471-2168
800/334-9491
Nevada
Stan Marshall
702/687-5394
New Hampshire
David Chase
603/271 -4674
800/852-3345 x 4674
New Jersey
Tonalee Carlson Key
609/987-2131
800/648-0394
New Mexico
Ron Mitchell
505/827-4300
New York (State Health)
William J. Condon
518/458-6495
800/458-1158
North Carolina
Felix Fong
919/571-4141
North Dakota
Arlen Jacobson
701/221-5188
Ohio
Marcia Howard
614/644-2727
800/523-4439
Oklahoma
Louis E. Smith
405/271-8118
Oregon
George Toombs
503/731-4014
Pennsylvania
Michael Pyles
717/783-3594
800/237-2366
Puerto Rico
David Saldana
809/767-3563
Rhode Island
Edmond Arcand
401/277-2438
South Carolina
Albert Craft
803/734-4631
800/768-0362
South Dakota
Mike Pochop
605/773-3351
800/438-3367
Tennessee
Susie Shimek
615/532-0733
800/232-1139
Texas
Gary Smith
(512)834-6688
Utah
John Hultquist
801/536-4250
Vermont
Paul Clemons
802/865-7730
800/640-0601
Virginia
Yunrui Xie
804/786-5932
800/468-0138
Washington
Kate Coleman
206/753-4518
800/323-9727
West Virginia
Beattie L. DeBord
304/558-3526
800/922-1255
Wisconsin
Conrad Weiffenbach
608/267-4795
Wyoming
Janet Hough
307/777-6015
800/458-5847
18
------- |