United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S8-88/084 Nov. 1 988
x°/EPA Project Summary
Preliminary Diagnostic
Procedures for Radon Control
B. H. Turk, J. Harrison, R. J. Prill, and R. G. Sextro
Analytical procedures for diagnosing
radon entry mechanisms into buildings
are described. These diagnostic
methods are generally based on the
premise that pressure-driven flow of
radon-bearing soil gas into buildings is
the most significant source of radon in
houses with elevated concentrations,
although procedures to determine the
contributions of other potential sources
(e.g., building materials and potable
water) to indoor airborne concentrations
are also included. Flowcharts are
presented that develop a logical se-
quence of events in the diagnostic pro-
cess, including problem diagnosis,
selection and implementation of mitiga-
tion systems, and post-mitigation evalua-
tion. The initial problem assessment pro-
cedures rely on an organized set of
measurements to characterize the struc-
ture, the surrounding soil, and the like-
ly entry pathways from the soil into the
building. The measurement procedures,
described in detail, include radon grab
sampling under both naturally and
mechanically depressurized conditions,
visual and instrumental analyses of air
movement at various substructure loca-
tions, building leakage area tests, and
soil characterization methods. Post-
mitigation evaluation procedures are
also described. Samples of various data
forms and test logs are provided.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Triangle
Park, NC, to announce key findings of the
research project that is fully documented
in a separate report of the same title (see
Project Report ordering information at
back).
Introduction
With the discovery of high indoor radon
(Rn-222) concentrations in a significant
number of houses since the late 1970s, it
has become important to develop a better
understanding of the mechanisms of radon
movement into and accumulation in
buildings and suitable methods for control-
ling or eliminating the accumulations. In
general, earlier research has found that the
most significant source of indoor radon is
the soil surrounding the building shell from
which radon migrates into the building,
transported by the pressure-driven flow of
soil gas. Factors influencing the radon en-
try rate include indoor-outdoor air temper-
ature differences, wind loading, soil
characteristics, construction details of the
building superstructure and substructure,
and the coupling between the soil and the
substructure.
To further investigate radon control
techniques, the U. S. Environmental Pro-
tection Agency (EPA), the Department of
Energy (DOE), and the New Jersey Depart-
ment of Environmental Protection (NJDEP)
funded an intensive study in 14 northern
New Jersey houses. The research was con-
ducted by the Lawrence Berkeley
Laboratory (LBL) in seven houses and col-
laboratively by Oak Ridge National
Laboratory and Princeton University in the
remaining seven houses. The following
overall objectives were established for the
project:
- Extend the understanding of the fun-
damentals of soil gas flow and radon
entry into buildings and improve the
basic knowledge of factors that in-
fluence the entry rate.
- Refine and develop analysis pro-
cedures for diagnosing radon entry
mechanisms and selecting appropriate
control systems.
- Develop and demonstrate practical
radon mitigation techniques for
selected basement/crawl space
houses.
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The research plan to meet the above ob-
jectives had four main components: 1)
house and site characterization
measurements, 2) baseline and continuous
monitoring of environmental and building
parameters, 3) diagnostic procedure
development, and 4) installation and opera-
tion of selected mitigation techniques.
Diagnostic Procedures
This report focuses primarily on the se-
cond objective: i.e., the preliminary
development of diagnostic procedures.
Diagnostic procedures are defined here as
organized and logical measurements, tests,
and observations that are necessary for
identifying the specific means by which
radon enters and accumulates in a par-
ticular structure. These procedures should
point the way to a suitable system or techni-
que for controlling indoor radon levels.
These procedures may also be applied as
follow-up measurements, tests, and obser-
vations useful in optimizing mitigation
system performance. This development ef-
fort builds on the previous, on-going, and
generally unpublished work of others, in-
cluding Scott, Tappan, Ericson, and Bren-
nan, as well as on the basic scientific
understanding developed by Nazaroff,
Nero, Tanner, and others. This report pro-
vides a format for refinement, reduction and
interpretation of the measurements and
observations necessary for selecting an ap-
propriately designed, effective, and
economical system for controlling indoor
radon concentrations in single-family
detached houses. Table 1 lists the
diagnostic research measurements and
procedures discussed in this report.
The premise for many of the diagnostic
procedures developed and discussed here
is that the pressure-driven flow of radon
bearing soil gas is the most significant
source of radon in houses with elevated
concentrations. However, other potential
sources of radon, such as water and
building materials are also included in the
diagnostic procedures. Figure 1 outlines
the mitigation process framework govern-
ing the use of diagnostic measurements.
The procedures described here rely on
individual site-specific observations and
short term measurements of air flow,
pressure differentials, radon concentrations
and near-building material characteristics.
The measurements are then used to iden-
tify primary radon sources (water, building
materials, soil) and most probable radon
entry points and mechanisms. Tools and in-
struments listed in Table 2 are necessary
to conduct the diagnostic procedures
discussed in this report. The report
Table 1. Project Measurements and Procedures
> Visual Inspection of House
• Alpha Scintillation Cell Radon Grab Samples
' Sub-slab and Wall Air Flow Communication Tests
< Air Infiltration Leakage Tests
' Appliance Depressurization Effects
< Soil Characterization
< Radon in Water
< Radon Flux from Building Materials
Problem Diagnosis
• Measure heating season indoor radon concentrations
• Evaluate non-soil sources
9 Characterize structure and soils and identify entry points
Selection and Implementation of Mitigation Systems
• Consider results of diagnostic measurements
• Review options for mitigation
• Develop and implement mitigation plan
Post-Mitigation Evaluation
• Monitor indoor air concentrations
• Measure mitigation system operating parameters
Successful
— ~ — (Improve System Efficiency)
Figure 1. General plan for radon control
assumes that the reader has prior ex-
perience with flow and pressure measur-
ing devices, and alpha particle counting
techniques. The full report describes the
Unsuccessful
(Modify System] —
or
(Install Additional Options)
diagnostic procedures forms used for data
recording and a sample application of
diagnostics in a house studied as part of
the aforementioned comprehensive study.
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Table 2. Instruments and Equipment
Radon Grab Sampling:
Air Leakage and Flow
Measurements:
Soils Characterization:
Inspection Equipment:
Tools:
Miscellaneous:
Alpha scintillation cells
Portable photomultiplier tube counting station
Hand pump with sample tube and 0.8 cm filter
Compressed air or nitrogen for cell flushing
Vacuum pump for evacuating cells (70 cm, 27 in. Hg vacuum)
Calibrated-flow blower door (6800 m3fr', 4000 cfm @ 5 Pa)
Pitot tubes (electronic or liquid-filled manometers: 1-50 kPa)
Hot wire anemometer (with temperature sensing element)
Smoke tubes
Industrial vacuum cleaner (170 m3fr', 700 cfm @ 2 m HzO pressure)
1.5 m (5 ft) flow sections of: 7.6 cm (3 in.) PVC with coupler
15 cm (6 in.) galvanized duct
Non-toxic tracer gas (SFe, Freon-12)
Tracer gas detection instrument
Soil core and auger samplers
3/4 in. reversible electric drill
Soil air permeability device
Sliding hammers
Various diameter drill bits, include some
attached 1.5 m (5 ft) long extensions
1.5 m (5 ft) long probe pipes
Stiff wires
Telescoping mirrors
Portable gamma spectrometer
Fiber optics scope
3/8 in. variable-speed hand drill
Masonry bits
1/2 in. hammer drill
Impact bits
Pocket flashlights
Hand sledge
Pry bar
Pipe wrench
Locking pliers
Adjustable wrenches
Portable lights
Step ladders
Long blade screwdriver
Forms
Inspection hole plugs
Epoxy-based mortar patch or hydraulic cement
Duct tape
Duct seal
0.3, 0.6, 1 cm (1/8, 1/4, 3/8 in.) diameter tubing
Various-sized hypodermic needles
Plastic film
Thermometers: electronic and mercury-filled glass
Silicone sealant
have been developed for identifying the
sources of indoor radon problems and
selecting systems for controlling radon. In
houses where the recommended remedial
measures have been installed, based on
the diagnostic measurements, radon con-
centrations have fallen below the guideline
of 4 pCi/L However, a rigorous process for
selecting successful, optimized systems
has not yet been developed for widespread
use by technicians and contractors.
Three new, and largely unvalidated
techniques are presented that may assist
in determining contributions to indoor radon
levels from the domestic water supply and
building materials and the approximate
distribution of air infiltration leakage area
in a structure. This document reports on
progress in research still underway. Addi-
tional data and observations are being
made that may support, augment, or in
some cases invalidate, some of the conclu-
sions discussed here.
Other diagnostic techniques and tools
under invesitgation in this and other studies
include: use of tracer gases to quantify en-
trainment of building air into subsurface
ventilation systems; creating flow and
pressure maps for hollow block foundation
walls; quantifying and apportioning subsur-
face ventilation from below slabs and from
within block walls; estimating outside air
ventilation that enters along the soil/house
interface; and development of a radon "snif-
fer" with faster recovery time between
samples taken from test holes, entry points,
and indoor air. Another new method will at-
tempt to challenge an installed mitigation
system by using a depressurization fan to
gradually increase substructure depressuri-
zation and thereby determine the system
failure point.
The report discusses details of the
various diagnostic methods, techniques,
and procedures currently under develop-
ment, and provides in flowchart form a
logical sequence of steps that will guide the
reader through the measurement and
evaluation mitigation process. The em-
phasis of this system of diagnosis is for
research purposes and is intended to serve
as the basis for development of approaches
for general commercial applications.
The report provides a house-specific ex-
ample of the above diagnostic procedures
with the purpose of demonstrating and
evaluating their utility in the mitigation pro-
cess. Preliminary diagnostic procedures
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B. Turk, J. Harrison, R. Prill, and R. Sextro are with the University of California,
Berkeley, CA 94720.
David C. Sanchez is the EPA Project Officer (see below).
The complete report, entitled "Preliminary Diagnostic Procedures for Radon
Control," (Order No. PB 88-225 115/AS; Cost: $14.95, subject to change)
will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
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
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