United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-93/197 December 1993
Project Summary
Follow-Up Radon Measurements
In 14 Mitigated Schools
J-C Dehmel, P.L. McCloskey, and G. Mollyn
To determine the long-term perfor-
mance of radon mitigation systems in-
stalled in U.S. Environmental Protec-
tion Agency (EPA) research schools,
radon measurements were conducted
in 14 schools that had been mitigated
between 1988 and 1991. The measure-
ments were made between February
and April 1992. A measurement proto-
col was developed based on current
EPA guidelines, and measurements
were made with alpha track detectors
(ATDs) which were mailed to the
schools along with placement and re-
trieval instructions.
The results from these follow-up ATD
measurements indicate that, overall,
active soil depressurization (ASD) sys-
tems have been very effective in main-
taining low long-term radon levels in
the 14 schools. Of the 409 locations
measured in these schools, only 17
(4%) of the measurements in mitigated
areas exceeded 4 pCi/L. Eight of the 17
measurements were in the one base-
ment school that was measured, one
was in a room where the ASD fan had
been turned off, and another was in a
room with building pressurization that
is only operated while the building is
occupied. If these 10 measurements are
dropped from the set, the rooms above
4 pCi/L drop to less than 2%.
The results of the quality assurance
audits and ATD spiking measurements
indicated that the project data quality
objectives were generally met. However,
some schools were not able to expose
the ATDs for the specified 3-month pe-
riod because of operational and
adminmistrative reasons. In addition, a
number of the duplicate ATDs were not
co-located within the room, contribut-
ing to the variation between duplicates.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Tri-
angle Park, NC, to announce key find-
ings of the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
The U.S. Environmental Protection
Agency's (EPA's) Air and Energy Engi-
neering Research Laboratory (AEERL) has
conducted radon mitigation research in
nearly 50 public schools since 1987. Ac-
tive soil depressurization (ASD) systems
have been installed in many of these
schools. After system installation, 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 sys-
tem was modified and radon levels were
remeasured.
To determine the long-term performance
of these mitigation systems, radon mea-
surements 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. The measurements were made with
alpha track detectors (ATDs) which were
mailed to the schools along with place-
ment and retrieval instructions. Quality
Assurance (QA)/Quality Control (QC) re-
quirements are applicable to this project.
The work was performed under the re-
Printed on Recycled Paper
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quirements of AEERL's QA Plan Category
III, and data are supported by QA/QC
documentation as required by the U.S.
EPA policy.
Measurement Methods and
Procedures
Telephone contacts were made with
each of the eight school systems to verify
their participation in the measurement
study and arrangements were made to
ship the ATDs and instructions to desig-
nated contacts. The ATD packages were
mailed between January 31 and February
7, 1992. The packages included:
1) instructions and data sheets,
2) a completed sample data sheet,
3) a marked-up floor plan showing
the proposed ATD deployment
locations in the school, including
those for duplicates,
4) ATDs, including control and du-
plicates, as separate packages,
5) ATD gold seals, and
6) a self-addressed return label and
shipping form.
During the survey, each school was con-
tacted by phone to establish placement
and retrieval dates. It was requested that
all ATDs and related documentation be
returned by April 20, 1992.
Radtrak ATDs, supplied by Tech/Ops
Landauer, Glenwood, IL, were used for
the measurements. Upon receipt, 102
ATDs were set aside for exposure, as
spikes, with the EPA's National Air and
Radiation Environmental Laboratory
(NAREL) test facility located in Mont-
gomery, AL.
Once the exposed ATDs and support-
ing documentation were returned, all ATDs
were counted, checked for proper identifi-
cation, and forwarded to Tech/Ops
Landauer for processing. Upon receipt of
the measurement results, the data were
sorted by school, and maximum, minimum,
average, and standard deviation of the
radon levels were determined.
J-C Dehmel, P.L. McCloskey, andG. Mollyn are with S. Cohen and Associates, Inc.,
McLean, VA 22101.
Kelly W. Leovic is the EPA Project Officer (see below).
The complete report, entitled "Follow-up Radon Measurements in 14 Mitigated
Schools," (Order No. PB94-114798AS; Cost: $ 19.50; subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
Results and Conclusions
The results from the follow-up ATD mea-
surements indicate that, overall, ASD sys-
tems have been very effective in main-
taining low radon levels in the long-term in
the 14 schools that were measured for
this study. Of the 409 locations measured
in these schools, only 17 (4%) of the mea-
surements in mitigated areas exceeded 4
pCi/L. Eight of the 17 measurements were
in the one basement school that was mea-
sured, one was in a room where the ASD
fan had been turned off, and another was
in a room with building pressurization that
is only operated while the building is oc-
cupied. If these 10 measurements are
dropped from the set, the rooms above 4 pCi/
L drop to less than 2%.
The results of the QA audits and ATD
spiking measurements indicate that the
project data quality objectives were gen-
erally met. However, some schools were
not able to expose the ATDs for the speci-
fied 3-month period because of opera-
tional and administrative reasons. In addi-
tion, a number of the duplicate ATDs were
not co-located within the room, contribut-
ing to the variation between duplicates.
•U.S. Government Printing Office: 1994 — 550-067/80134
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Environmental Protection Agency
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EPA/600/SR-93/197
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