United States
Environmental Protection
Agency
EPA-600/8-88-084
June 1988
ERA Research and
Development
PRELIMINARY
DIAGNOSTIC PROCEDURES
FOR RADON CONTROL
Prepared for
Office of Radiation Programs
Prepared by
Air and Energy Engineering Research
Laboratory
Research Triangle Park NC 27711
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EPA-600/8-88-084
June 1988
PRELIMINARY DIAGNOSTIC PROCEDURES
FOR RADON CONTROL
B.H. Turk, J. Harrison, R.J. Prill, and R.G. Sextro
Indoor Environment Program
Applied Science Division
Lawrence Berkeley Laboratory
University of California
Berkeley, California 94720
EPA Project Officer
D.C. Sanchez
Combustion and Indoor Air Division
Air and Energy Engineering Research Laboratory
Research Triangle Park, NC 27711
This study was cofunded by EPA through
Interagency Agreement DW89931876-01-0
and by the Department of Energy
through contract DE-AC03-76SF00098.
OFFICE OF ENVIRONMENTAL ENGINEERING
AND TECHNOLOGY DEMONSTRATION
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, DC 20460
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DISCLAIMER AND PEER REVIEW
This work is cofunded by the U.S. Department of Energy (DOE) and by the U.S.
Environmental Protection Agency (EPA). DOE support was from the Assistant
Secretary for Conservation and Renewable Energy, Office of Building and Community
Systems, Building Systems Division, and from the Director, Office of Energy Research,
Office of Health and Environmental Research, Pollutant Characterization and Safety
Research Division under Contract No. DE-AC03-76SF00098. EPA support, under
Interagency Agreement No. DW89931876-01-0 with DOE, was through the Office of
Environmental Engineering and Technology Demonstration, Office of Research and
Development. This report has been subjected to EPA's peer and administrative review,
and it has been approved for publication as an EPA document. Approval does not
signify that the contents necessarily reflect the views and policies of the EPA or DOE,
nor does mention of trade names or commercial products constitute endorsement or
recommendation for use.
ABSTRACT
A preliminary set of analytical procedures for use in diagnosing radon entry
mechanisms into buildings is 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 homes with elevated concentrations, although
procedures to determine the contributions of other potential sources such as building
materials and potable water to indoor airborne concentrations are also included. A
series of graphical flowcharts are presented that develop a logical sequence of events in
the diagnostic process, including problem diagnosis, selection and implementation of
mitigation systems and post-mitigation evaluation. The initial problem assessment
procedures rely on an organized set of measurements to characterize the structure, the
surrounding soil and the likely entry pathways from the soil into the building interior.
The measurement procedures, described in detail in the text, include radon grab
sampling under both naturally- and mechanically-depressurized conditions, visual and
instrumental analysis of air movement at various substructure locations, 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.
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TABLE OF CONTENTS
Abstract ii
Lists of Figures, Tables and Appendices iv
Acknowledgments v
I. INTRODUCTION 1
A. Study Methodology 2
B. Limits of Discussion 2
II. OUTLINE OF GENERAL DIAGNOSTIC PROCEDURES 5
m. DISCUSSION OF DETAILED DIAGNOSTIC PROCEDURES 8
A. Premitigation Diagnostics 8
1. Characterize Structure and Identify Soil Gas Entry Points 8
Identify entry locations 8
Alpha-scintillation-cell Grab Samples of Radon 9
Soil Gas Movement 11
Air Infiltration Leakage Area 11
Subsurface or Near-surface Air Flow Communication 12
Appliance Effects 13
Soil Characterization 13
2. Radon in Water 15
3. Radon Flux from Building Materials 16
B. Summarize Test Data 17
C. Selection of Mitigation Systems 18
1. Crawlspaces 18
2. Other Substructure Types 19
Ventilation 19
Subsurface Ventilation 19
Block Wall Ventilation 20
Basement Overpressurization 20
Sealing of Cracks and Holes 20
D. Post-mitigation System Evaluation and Optimization 20
E. Application of Procedures in 14 New Jersey Houses 21
IV. SUMMARY 22
V. REFERENCES 23
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LISTS OF TABLES, FIGURES, AND APPENDICES
Tables
Table 1 Project Measurement Activities 3
Table 2 Instruments and Equipment 6
Table 3 Range of Soil Permeabilities 14
Fiaures
Figure 1 General Plan for Radon Control 25
Figure 2 Problem Diagnosis 26
Figure 3 Radon in Water 27
Figure 4 Radon Flux from Building Materials 28
Figure 5 Selection of Mitigation Systems 29
Figure 6 Mitigation Options 30
Figure 7 Post-mitigation Evaluation 31
Figure 8 Distribution of Structure Effective Leakage Areas 32
Figure 9 Diagnostic Measurements Interpretive Map 33
Figure 10 Pre- and Post-Subsurface Ventilation - LBL10 34
(Effect of Subsurface Ventilation on Basement
Radon Concentrations in One House)
Apppendices
Appendix A Radon Diagnostic Checklist A-l
Appendix B Radon Source Diagnosis Building Survey B-l
Appendix CI Site Plan C-l
Appendix C2 Site Elevation C-2
Appendix C3 Floor Plan - First Floor C-3
Appendix C4 Floor Plan - Substructure C-4
Appendix C5 Floor Plan - Second Floor C-5
Appendix D1 Radon Gas Sampling Log D-l
Appendix D2 Soil Permeability Survey D-2
Appendix D3 LBL/BPA Fan Test Data Sheet d-3
Appendix D4 Building Materials Sampling Log D-5
Appendix DS Soil Sample Log D-6
Appendix D6 Water Samples Log D-7
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ACKNOWLEDGMENTS
The authors would like to thank private contractors Terry Brennan, William
Broadhead, and Ronald Simon for their comments and contributions during the initial
diagnostic measurements and follow-up diagnostic measurement period; Lynn Hubbard
and Ken Gadsby at Princeton for suggestions and modifications to the original
diagnostic procedure; and A.B. Craig, W.J. Fisk, B. Henschel, M. Mardis, A.V. Nero,
Jr., and D.C. Sanchez for reviewing the document. And, of course, we greatly
appreciate the hospitality, courtesy, and commitment to this study by all of the
participating homeowners.
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I. INTRODUCTION
With the discovery of high indoor radon (Rn-222) concentrations in a significant
number of residences since the late 1970's, it has become important to develop a better
understanding of the mechanisms of radon movement into and accumulation in
buildings and suitable methods for controlling 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 pressure-driven flow of soil gas. A few of the factors influencing the
radon entry rate include indoor-outdoor air temperature differences, wind loading, soil
characteristics, construction details of the building superstructure and substructure, and
coupling between the soil and the substructure.
In order to further investigate radon entry and radon control techniques, the U.S.
Environmental Protection Agency (EPA), the Department of Energy (DOE), and the
New Jersey Department of Environmental Protection (NJDEP) are funding an intensive
study in fourteen northern New Jersey homes. The research is being conducted by the
Lawrence Berkeley Laboratory (LBL) in seven homes and collaboratively by Oak
Ridge National Laboratory and Princeton University in a second set of seven homes.
Since few studies have attempted to relate influencing factors to entry rates and to
investigate the importance of these factors on systems designed for radon abatement,
the following overall objectives were established for this project.
- Extend our understanding of the fundamentals of soil gas flow and radon entry
into buildings and improve our basic knowledge of factors that influence the entry
rate.
Develop a better understanding of the success or failure of certain mitigation
techniques and of the operational ranges of key parameters that affect the utility of
these techniques.
Refine and develop analysis procedures for diagnosing radon entry mechanisms and
the selection of appropriate control systems.
The basic research plan for this project has four main operational 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 operation of selected mitigation techniques.
This report focuses primarily on item 3, development of diagnostic procedures.
Diagnostic procedures are defined here as an organized and logical set of
measurements, tests, and observations that are necessary for identifying the specific
means by which radon enters and accumulates in a particular structure. In addition,
these procedures should point the way to a suitable system or technique for controlling
the indoor radon levels. These procedures may also encompass follow-up
measurements, tests, and observations important in optimizing mitigation system
performance. This development effort builds on the previous, on-going, and generally
unpublished work of others, including Scott, Tappan, Henschel, Ericson, and Brennan,
as well as on the basic scientific understanding developed by Nazaroff, Nero,'and
others at LBL. Hopefully, it provides a format for refinement, reduction and
interpretation of the measurements and observations necessary for selecting an
appropriately designed, effective, and economical system for controlling indoor radon
levels in a majority of existing U.S. single-family houses with elevated radon
concentrations.
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A. Study Methodology
The 14 participating New Jersey homes were selected from a larger group of
approximately 130 New Jersey homes based on various criteria including representative
construction types, soil characteristics, and accessibility to interior basement walls and
floors. With the homeowners' consent, a large number of diagnostic measurements have
been made, suitable control systems have been selected, installed (in some houses a
second competing system will be installed) and operated, and follow-up diagnostic
measurements are being performed while system performance is monitored and
optimized. This process is still in progress. Because revisions will be and are being
made to the procedures discussed here, this report should be considered preliminary.
The other major research objective, that is developing a better understanding of
the fundamental factors influencing radon entry, goes beyond but is supportive of the
development of diagnostic procedures. Tasks in support of this broader objective
include continuous data collection, periodic measurements and specific experiments
conducted throughout the project. Measured parameters are detailed in Table 1. In
the seven-home LBL study, radon is being continuously monitored in one substructure
location and one first floor location using continuously pumped room air sample
through an alpha scintillation cell and counter and recorded on a data logger. These
devices are operated during premitigation baseline conditions to establish pre-existing
indoor radon concentrations and during post-mitigation measurement periods. Other
parameters are also recorded on the data logger such as continuous radon concentrations
below basement slabs, indoor and outdoor temperatures, subslab soil temperatures, near-
structure soil temperature and moisture, windspeed and direction, and pressure
differentials continuously monitored across the basement slab and across the
substructure/ambient interface. Seven-day average indoor water vapor concentrations
are monitored with passive samplers. Barometric pressure and rainfall are continuously
monitored at one house. In addition, occupants are requested to complete forms
summarizing daily activities that might affect the indoor environment. Technicians also
periodically conduct other measurements. Evaluation of daily and seasonal impacts on
radon entry and mitigation system performance will then be possible. There will be
little additional discussion of these efforts in this report.
B. Limits of Discussion
This document is not intended to provide detailed guidance for the practical
application of diagnostic procedures. Many of the techniques and measurements used
in these diagnostic procedures are solely for the support of specific research aspects of
this project. As a result, few private consultants or contractors will be capable of
purchasing the equipment or receive the training necessary to perform the
measurements utilized here while still being competitive and profitable in the
marketplace. In fact, the use of the diagnostic procedures discussed here may be
prohibitively expensive to building owners and managers and, therefore, will see little
use in their present form. This may be particularly true for houses with concentrations
between 4 pCi/L* and approximately 20 pCi/L, since the perceived health risk at those
levels may not be significant enough to warrant large expenditures for diagnosis and
mitigation.
•This report discusses radon concentrations in units of picocuries per liter, pCi/L, still
commonly used in the U.S. The conversion to SI units is 1 pCi/L - 37 Bq/m .
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TABLE 1: Project Measurement Activities
1) Parameters to be monitored continuously:
• indoor radon concentrations (various locations within the house), and possibly
radon progeny concentrations (smaller subset of houses),
• outdoor and indoor temperatures,
• meteorological parameters at each site, including windspeed and direction,
• pressure differentials across the building shell (various locations),
• soil moisture and temperature, and
• barometric pressure and precipitation at one central site.
2) Parameters to be monitored periodically:
• soil air permeability,
• ventilation rate,
• indoor water vapor,
• soil gas radon concentrations at selected locations, and
• occupant effects and activities, including operation of a fireplace or wood
stove, forced air furnace systems, exhaust fans, etc.
3) Parameters to be measured once or occasionally:
• effective leakage area,
• radon progeny concentrations,
• soil characteristics (at LBL), including permeability, grain size distribution, soil
radium concentration, and emanation ratio,
• frost depth and snow cover,
• pressure-field mapping to determine coupling between building shell and
surrounding soil,
• tracer gas (SF_) injection in soil and resulting concentrations within the
building shell (ir utilized), and
• additional parameters specific to the mitigation technique under investigation,
such as the flow rate of air through a block wall or subslab ventilation system,
or tracer gas analysis of flow pathways.
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However, this current set of methods for diagnosing radon problems is necessary
for the development of practical and useful procedures that can be used by persons
requiring less technical training and equipment. Over the next several years, further
refinements (including the assembly of "expert systems") may make diagnoses easier and
improve the probability for successful selection of appropriate radon control systems.
An area that requires additional work is that of mitigation system selection. At
present, data collected during diagnostic measurements are valuable only to those
already familiar with selection and installation of mitigation systems. Defining the
process that rigorously indicates selection of the "correct" control system for a particular
house is not an objective of this work, although some progress is made toward that
goal.
Finally, this is not a report on the details of specific mitigation techniques. Other
papers (some of which are listed in the references) discuss these techniques and systems
more fully. Details and evaluations of the mitigation systems used in this study will be
subjects of a later report.
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II. OUTLINE OF GENERAL DIAGNOSTIC PROCEDURES
The premise for much 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. While further discussion of this premise
is beyond the scope of this report, the reader should refer to DSMA, (1985) and
Nazaroff, et al., (1985a, 1985b, 1986) for additional discussion. On the other hand,
other potential sources of radon, such as water and building materials, are also included
in the diagnostic procedures discussed here. A good overall review is found in Nero
and Nazaroff, (1984).
The procedures described here rely on a series of individual site-specific
observations and measurements of air flow, pressure differentials, radon concentrations
and near-building material characteristics. This collection of measurements is then
used to identify primary radon sources (water, building materials, soil) and most
probable radon entry points and mechanisms. Various tools and instruments (see Table
2) are necessary to conduct the diagnostic procedures discussed here and this report
assumes that the reader has prior experience with flow and pressure measuring devices,
and alpha particle counting techniques. Samples of forms for recording this diagnostic
information are found in Appendices A, B, C, D and are referred to in the text.
Some investigators have used gamma radiation surveys as a method of locating
radon source materials. Making and interpreting results of such surveys in buildings
appears to pose a number of difficulties and we have not utilized this technique here.
Since soil gas flows are the meat significant source of radon in houses, the location and
extent of penetrations through the building shell, along with physical characteristics of
the surrounding soil (such as air permeability) are the most important determinants of
radon entry and source locatoin. Variations of apparent radium and/or radon
concentration in the soil near the building may not be correlated with entry locations.
The methods we discuss here, particularly air sampling for radon at suspected entry
points and in areas where radon accumulation is likely, provides a more direct method
of identifying radon sources and entry locations.
Radon, not radon progeny, is measured before, during, and after diagnostics and is
the contaminant on which control efforts are focussed. In its role as progenitor,
control of radon also controls radon decay products, which are responsible for the
adverse health risks associated with radon exposures. There are some potential
mitigation measures directed at progeny control only, such as air cleaning. These are
not considered here.
Before diagnostic procedures for radon control are employed, the indoor radon
concentrations on any occupied floor in a particular structure should be verified during
the heating seasons as being greater than the recognized guideline. Methods and
procedures for determining indoor radon concentrations during non-heating season
periods are being studied. However, relationships between heating season and non-
heating season concentrations in homes with elevated concentrations have not been
established. In this report, EPA's suggested guideline of 4 pCi/L annual-average
concentration is used as a conservative heating season worst case target in diagnosis and
in determination of successful mitigation. Ultimately, these heating season
measurements would predict the annual average concentration. However, at this time,
we are unable to make that prediction. The basic procedure here can be used with
different guidelines. For example, in an area with many homes with indoor
concentrations greater than 20 pCi/L, these houses might be the main objective of
diagnostic and remedial efforts during the next several years.
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TABLE 2: Instruments and Equipment
Radon Grab Sampling: Alpha scintillation calls
Portable photomultiplier tuba counting station
Hand pump with sample tub* and 0.8 /on filter
Compressed air or nitrogan for call flushing
Vacuum pump for evacuating calls (70 cm, 27 in. Bg vacuum)
Air Leakage and Flow
Measurements:
Calibrated-flow blower doer (8800 a h , 4000 cfm 9 3 Fa)
Pitot tubea (electronic or liquid-filled manometers: 1-50 kFa)
Hot wire anemometer (with temperature sensing element)
Smoke tubea
3 *1
Industrial vacuum oleaner (170 m b , 100 cfm 8 2m, 80 in. H^O pressure)
1.3 a (3 ft.) flow sections of : 7.6 cm (3 in.) FVC with coupler
13 cm (8 in.) galvanised duct
Non-toxic tracer gas (SFg, Freon 12)
Tracer gas detection instrument
Soils Characterization:
Soil core and auger aanplera
3/4" reversible electric drill
Soil air permeability device
Sliding hammers
Various diameter drill bits, including some
attached 1.3 ¦ (3 ft.) long extensions
1.3m (3 ft.) long probe pipes
Inspection Equipment: Stiff wires
Telescoping mirrors
Portable gamma spectrometer
Fiber optica scope
Tools: 3/8" variable speed bend drill
Masonry bits
1/2" haimer drill
Impact bita
Pocket flashlights
Hand sledge
Pry bar
Pipe wrench
Locking pliers
Adjustable wrenches
Portable lights
Step ladders
Long blade screwdriver
Miscellaneous: Forms
Inspection hole plugs
Epoxy-based mortar patoh or hydraulic cement
Duet tape
Duct seal
0.3, 0.8, 1 cm (1/8, 1/4, 3/8 in.) diameter tubing
Various-sized hypodermic needles
Plastic film
Thermcnetera: electronic end mercury-filled glees
Silicone sealant
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Due to the potential for large variations in indoor radon concentrations in the same
house, short term measurements (less than 4 days) are not adequate to eliminate the
possibility of false positives or negatives. Therefore, two separate 7-day measurements
using a continuous radon monitor or one 14-day minimum alpha track average
measurement of indoor radon levels during the heating season are recommended here.
If concentrations during both 7-day periods are higher (or lower) than the guideline,
one can be more confident that the measurements represent typical heating season
indoor concentrations for that house. If the concentrations from these measurements do
not replicate, i.e., one measurement is above the guideline while the other is below,
then a third (and perhaps of longer duration) test should be conducted or diagnostic
procedures begun. The EPA recommends a slightly different schedule of follow-up
measurements based on the initial test result concentrations (Ronca-Battista, et al.%
1986).
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III. DISCUSSION OF DETAILED DIAGNOSTIC PROCEDURES
A "General Plan for Radon Control", shown in Figure 1, outlines the basic process
for mitigating elevated radon levels. Once a structure is determined to have a radon
problem, a survey of the structure is conducted that characterizes soil-linked radon
entry points in the building shell and evaluates potential non-soil sources. After
reviewing the results of the diagnostic measurements, suitable options for radon
mitigation are considered and a final plan for the control system(s) is developed.
Follow-up measurements of indoor air concentrations and system operating conditions
are made once the installations are completed. If follow-up short-term diagnostic
measurements of indoor radon concentrations are still greater than the guideline, then
modifications or additional system options must be installed. For apparently successful
installations, the system is tuned for improved efficiency (/.?., effective performance
with reduction in system size requirements) and more economical operation and the
reduced indoor levels are verified with a 14-day average heating season measurement.
The following discusses details of the various diagnostic methods, techniques, and
procedures currently under development. Figures 2-7 in flowchart-graphical form
show a logical sequence of steps that will assist in guiding the reader through the
measurement and evaluation process. We emphasize again that this system of diagnosis
is for research purposes and is intended to serve as the basis of somewhat simpler
approaches for general application.
A. Premltigatlon Diagnostics
A complete evaluation of a house with elevated radon concentrations should
consider all sources, including soil-based sources such as convective soil gas flow
through cracks and holes and diffusive flow through the building membrane, as well as
non-soil sources such as water and building materials. Problem diagnosis begins with
Figure 2 #1, "Conduct Visual Inspection". This building survey is undertaken using a
checklist (Appendix A) and a form such as in Appendix B to identify all potential areas
that may be contributing to elevated indoor radon levels. Although the majority of
indoor radon problems can be traced to soil-based convective or diffusive flows, the
survey encourages an initial inspection of building materials and a measurement of
water radon concentrations where water is from a local well. See Figures 3 and 4.
1. Characterize Structure and Identify Soil Gas Entry Points
Identify Entry Locations
Convective flow of soil gas containing radon into buildings is the most frequent
cause of excessive radon concentrations in indoor air and contributes to elevated indoor
radon levels when there are 1) entry locations through the substructure where radon
bearing soil gas can pass into the building, 2) relatively higher soil gas radon
concentrations in the soil near the structure, and 3) sufficient soil air permeability to
permit flow of soil gas.
During the visual inspection of the house, soil-based radon entry possibilities are
tentatively identified. The survey questionnaire and floor plans (Appendices B and C)
are especially useful tools in identifying likely entry locations. Examples of
drawings/floor plans are illustrated Appendices C1-C5. The survey questionnaire form
requires very detailed and specific information about construction type, materials,
conditions of materials and surfaces, mechanical equipment, imperfections that can
allow soil gas entry, and building occupancy. This information is essential to a
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thorough understanding of the building and its operation and ultimately to the design
of a suitable radon control system(s).
The visual inspection should include probing of likely entry points in the
substructure. Using a stiff wire, screwdriver, and chemical smoke tube, and possibly a
fiber optics viewing scope, all substructure surfaces in contact with the soil should be
examined to determine if cracks and holes may penetrate or connect to the soil. Under
natural heating season conditions the smoke tube may detect soil gas movement in or
out of the opening. Significant openings would include wall or floor cracks and holes,
the interface between various masonry material surfaces such as floor/wall joint (where
the floor slab is poured against the substructure wall), gaps around utility services
penetrations, floor drains, and the tops of block walls. These should be noted on the
survey form and located on the floor plan.
To allow for additional inspection sites, tests of subsurface pressure field extent
and ventilation communication tests, and subsurface grab sampling, small 1 cm (3/8 in.)
diameter holes are drilled into and through various substructure surfaces (0.6 cm, 1/4
in., diameter holes for hollow block walls). The number and location of these holes
depend on the configuration and size of the substructure. Our current experimental
practice requires approximately three to four slab holes: one in each corner of the slab
(approximately 1 m; 3 ft. from each wall), one hole through each wall (approximately
1/3 the height of the wall above the floor), and one hole drilled into an open cell of
every sixth block in the second row of blocks above the slab floor. In addition, a
larger central hole, 2 to 4 cm (3/4 to 1-1/2 in.) in diameter is drilled through each slab
and at least one block wall so that a powerful industrial or shop-type vacuum cleaner
can be attached to conduct subsurface communication tests. Holes are plugged with a
removable temporary seal of putty-like material (duct seal, Mortite®) until the
completion of all diagnostics and mitigation. Upon completion of the mitigation, the
holes will be permanently sealed.
Alpha-scintillation-cell Grab Samples of Radon
To determine if any building zones have relatively high indoor radon levels that
would help identify a predominant area of radon entry and to attempt to more
specifically locate substructure entry points, grab samples of air are then collected.
They are taken from each unique building zone (garage, first floor, second floor,
basement, crawlspace, rooms that are slab-on-grade), the ambient outside air, and
selected entry points and inspection holes. These samples are taken under natural
conditions (Figure 2 #2) in the structure, influenced only by the existing environmental
variables, such as wind speed, outside air temperatures soil moisture and temperature.
Measured values of these variables should be recorded at time of sampling (see
Appendix Dl). Grab samples are collected again with the building mechanically
depressurized, as discussed below.
Alpha scintillation cells (Lucas cells) with zinc sulfide coating and 100 - 200 ml
internal volume are used to collect the samples. Prior to use, these cells are purged of
any radon or radon progeny using filtered outside air or aged compressed gas (air or
nitrogen), and a 2-minute background count is performed with a portable
photomultiplier tube scintillation counter to ensure that the cells are free of radon. A
gas sample is taken with a sample probe consisting of small diameter tubing, a
hypodermic needle, or other appropriate fitting, an 0.8 pm filter assembly, the Lucas
cell and a small hand-operated vacuum pump. The hand pump is used to flush the
sample train with the gas sample. The cell, previously evacuated with the hand pump,
is then opened and allowed to pull in the intended sample. Sufficient time is allowed
for the cell to reach atmospheric pressure before the cell is sealed.
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Since these samples are to be used only for diagnostic purposes and an indication
of the relative concentration of radon gas, it is not necessary to wait for the radon gas
and progeny in the cell to reach equilibrium (approximately 3 hours). It is important
to realize that air samples collected from test holes or entry points may initially contain
220Rn, thoron, as well as 222Rn, radon. Potential effects on the total alpha activity
observed in the cell due to 320Rn and 220Rn progeny decay can be minimized by
waiting at least 10 min before cell counting. The cells are analyzed by counting the
alpha activity in a photomultiplier tube counting station. Semi-quantitative results
sufficient for comparison of radon concentrations between samples can be obtained by
counting the activity for 2 minutes. For this short counting interval, care must be
taken to avoid exposing the coating on the cell walls to bright ambient light levels.
The light may activate the coating, producing scintillations that might be registered by
the counting station. These spurious scintillations are very short-lived and can also be
minimized by allowing approximately a one minute delay between the time the cell is
placed in the counter and the time counting commences. Following counting, the cell
should be purged immediately as indicated previously and not used again for sampling
for another 24 hours. Cells used for measurement of high concentrations can be
segregated for use only with high concentrations. These cells should be checked for
background before use. In addition, background activity should be checked in all cells
after at least every ten samples to monitor cell contamination.
Other grab samples should be taken after the building (or substructure only) has
been depressurized for approximately 30 minutes using a variable speed fan capable of
developing a -10 Pa pressure difference between the substructure and the outdoor
atmosphere (Figure 2, #3a-h). This simulates maximum heating season pressure-driven
forces on soil gas entry. While a smaller pressure difference (-3 to -5 Pa) is probably
more typical of heating season conditions, the slightly larger difference encourages a
more rapid radon entry response, tends to swamp variable environmental effects (wind
speed) during the procedure and minimizes radon depletion in the nearby soil that
might occur at higher pressure differences.
The mechanical depressurization may not cause representative distribution of radon
throughout the structure, depending on the distribution of the building's air infiltration
leakage area and location of the depressurization fan. Therefore zone room air grab
samples from the building may not suitably represent natural condition radon
concentrations.
Grab samples should be taken from all suspected entry points, drilled test holes,
inside firred wall stud cavities, floating slab gaps (French drains), and from wall and
floor cracks and wall/floor joints. The last two samples are often difficult to obtain.
One method that minimizes dilution of radon by room air involves taping over the
crack or joint approximately 0.6 m (2 ft) to either side of the sample location. Then,
depending on the width of the gap, a small tube, or if necessary, a hypodermic needle
is inserted into the gap through the tape and a sample is withdrawn. For French
drains, both ends of the taped section should also be plugged to prohibit ventilation of
the sample space. After collection, all samples are then counted and analyzed.
Based on previous experience, samples from locations with concentrations less than
or equal to the room air concentration are unlikely to identify radon entry source
points. Those with concentrations approximately two or three times room air
concentrations are possibly significant entry locations, and those with concentrations
greater than three times room air levels indicate likely source points for significant
radon entry.
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Soil Gas Movement
As an estimate of the mobility of soil gas under slabs, within block walls and
through suspected entry points, air movement can be qualitatively measured. The
amount of soil gas that can pass through a crack or hole may be valuable in defining its
importance as a radon entry point. However, some minute CTacks will show no visible
evidence of air movement, yet may still contribute to the flow of radon-bearing soil
gas into the building interior.
To check for the flow of soil gas at the suspected entry points and drilled test
holes, substructure depressurization is increased to -30 Pa, which exaggerates any
natural air movement (Figure 2, #4). Using chemical smoke from commercially
available smoke tubes, the direction and approximate velocity of soil gas movement
from the soil to the structure can be qualified. Other air movements can be identified
during this test, such as those out of the top of hollow-core block walls, at the exterior
soil line, and through various bypass paths between the substructure and upper floors
or attic. These bypasses may be important in enhancing the building's "stack effect"
which will increase substructure depressurization and soil gas entry. The "stack effect"
results from indoor air that is warmer and therefore more buoyant than outdoor air.
This causes pressure differences across the building shell at the top of the structure
forcing indoor air to the outside and at the bottom of the structure drawing outside air
(or soil gas) inside. Since the use of smoke does not quantify the air movement,
procedures employing a hot wire anemometer are presently under evaluation. In this
way, a mass flow rate of soil gas bearing radon into the building may possibly be
estimated for different entry points.
Air Infiltration Leakage Area
The effective leakage area for infiltration of air between the outdoors and the
building interior may be an important parameter in the selection of certain mitigation
options, such as basement pressurizatioa, heat recovery ventilation, and other
ventilation techniques. As shown in Figure 8, effective leakage areas for 1) the entire
structure, 2) the superstructure only, and 3) the substructure only fairly well
characterize the distribution of leakage through the building shell. This is important to
understanding radon distribution throughout the building and in controlling indoor
radon levels. For example, the whole building equivalent leakage area (ELA) can be
used with a model developed by Sherman and Grimsrud (1980) to estimate the natural
or existing ventilation rate of the building for considering the installation and sizing of
a heat recovery ventilator.
The ELA of the substructure ceiling and substructure floor and walls can be
normalized by the substructure floor area to give a specific leakage area (SLA, in units
of cmJ/m3). The SLA can be used to compare substructures of different buildings and
to help decide if additional sealing is recommended to reduce the leakage area. The
SLA may also be useful as an index of substructure ventilation for the sizing of heat
recovery ventilators in the substructure.
Depressurization of the entire structure is accomplished by using a blower door,
located in a first floor exterior door with any access ways open to the substructure. All
other exterior doors and windows are closed. The leakage of the superstructure alone is
then measured by closing the accessways to the substructure* while exterior window;
and doors in the substructure are opened to allow the substructure to reach atmospheric
pressure. Finally, the leakage of the substructure alone can sometimes be measured by
locating the fan In 1) a substructure exterior door or window, or 2) a doorway between
die substructure and the superstructure. In the bitter case, the fan exhausts into the
-------
superstructure. In both cases, the superstructure exterior doors and windows are
opened to allow the superstructure to reach atmospheric pressure. These tests should be
made only after natural condition radon grab samples have been collected.
If basement pressurization is a possible mitigation option, the substructure surfaces
requiring additional air leakage tightening can be identified. In addition, by using the
depressurization fan, which must have a calibrated flow curve, the fan size necessary
for pressurizing the basement to control radon levels can be estimated. For this
measurement, it is preferable to operate the depressurization fan in the same way as the
radon control basement pressurization fan is operated; i.e., pressurizing the basement by
pulling air from the superstructure and exhausting it into the substructure. In this
configuration any valving action (dampers, etc.) between the two zones would mimic
actual operating conditions. All doors and windows should be closed. A typical
leakage test would be conducted over several points of pressure differential across the
building shell (Appendix D3). By applying a linear regression to the flow and building
shell pressure points, a linear estimate of the flow necessary to pressurize the basement
to +3 Pa can be calculated. This will determine whether basement pressurization is
practical and the size of the fan necessary to achieve it.
Estimates of the leakage area for the substructure ceiling and the substructure floor
and walls may be computed from the following relationships (Figure 8):
ELAW - ELAp + ELAb - 2ELAC . (1)
Rearranging equation (1) gives
ELAC ¦ ELAp + ELAjj - ELAW
(2)
In addition,
ELAf - ELAb - ELAC, (3)
where:
ELAW - whole building ELA,
ELA. - superstructure ELA,
ELA^ ¦ substructure ELA,
ELAC - substructure ceiling ELA,
ELAf - substructure basement walls/floor ELA.
It is important to note that the substructure leakage area (ELAk) and the
substructure wall/floor leakage area (ELAf) include leakage area to the soil as well as
to the outside. Data from the ELA measurements in the houses in this study are not
yet available.
Subsurface or Near-surface Air Flow Communication
The degree of ventilation communication below the floor slab and near the bottom
of the walls is another important diagnostic element both in understanding potential
radon transport and in assessing the possible use of subslab ventilation techniques for
mitigation. To determine the spatial extent of the pressure field that could result from
subsurface ventilation or block wall ventilation, a high vacuum (200 cm HjO static
pressure) industrial vacuum cleaner is connected to one of the several large holes drilled
through the slab or into the block walls discussed earlier (Figure 2, #6). A
12
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micromanometer or other sensitive pressure measurement device is used to measure the
direction and magnitude of the pressure difference (referenced to substructure pressure)
and chemical smoke (or a modified hot wire anemometer) to determine air flow
direction and approximate velocity at each each of the test holes including the vacuum
hole. During this test, the vacuum is cycled on and off and measurements are taken
under both conditions to account for any pre-existing pressure field or air flows
without the vacuum operating. It has been observed that certain soil and gravel
conditions have a longer response time to changing driving pressures; therefore,
measurements should be made only after a delay of approximately 1-2 minutes from
when the vacuum was switched on or off.
Often the pressure field developed at a point is less than the detection limit of the
micromanometer (1 Pa), yet can be detected by carefully observing the direction of
smoke movement at the hole. Those locations with the highest pressure differential and
greatest air flow into the hole generally have the best connection or communication
with the vacuum hole. Good communication can be due to highly permeable gravels or
soils, channels or cavities in the near-substructure fill material, proximity to the
vacuum hole, or - in the case of hollow-core block walls - little or no block fill
material. Floors or walls that evidence good communication with the vacuum test are
possible candidates for subsurface or block ventilation, except for those block walls
that have numerous and inaccessible openings to the outside or inaccessible block
openings to the inside. Because of the possibility of drawing large volumes of high
concentration radon-laden soil gas into the structure, the vacuum exhaust should be
vented to the outside during this test.
Appliance Effects
The operation of some fans and appliances, such as attic, bath and kitchen fans,
clothes dryers, combustion and forced air furnaces, and whole house vacuum cleaners,
may increase substructure depressurization as much as 10 to IS Pa (Figure 2, #7).
While exhaust fans and vacuum cleaners are typically operated for only short periods,
the other devices may operate for sufficiently long periods to measurably increase
radon entry. To measure the depressurization effect of these devices, they are cycled
on and off up to 20 times while substructure-to-ambient pressure differences are
measured with a micromanometer. The average difference between the on and off
condition is taken to be that caused by appliance operation. The large combustion air
requirements for some furnaces can cause measurable depressurization, while
unbalanced forced air furnaces that have either leaky substructure return air ducts or
plenums or insufficient substructure supply air usually have the most dramatic impact
on substructure depressurization. Attic or ceiling exhaust fans may also cause
substructure depressurization via bypasses between the two levels. While these
conditions can be remedied by supplying outside combustion air, sealing duct leaks,
balancing furnace delivery, or sealing attic bypasses, a radon entry problem would
probably still exist if it did initially.
Soil Characterization
Measurements of near-house soil air permeability and radium content may be
important in determining which, of pressurization or depressurization subsurface (or
weeping tile) ventilation systems, will be more effective in controlling indoor radon
levels (Figure 2, #8). Preliminary research indicates that, in highly permeable soils
with low to moderate radium concentrations, subsurface pressurization may be more
effective than depressurization (Turk, et al., 1986). However, at this time, a detailed
understanding of the relationship between permeability and radium content and the
success of various mitigation measures has not been established. The value of
13
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permeability data for selecting and designing other types of mitigation systems is
unknown. However, the measurement of soil air permeability at every structure
undergoing diagnosis would provide data useful in helping to understand the radon
entry problem and for future research purposes.
Field measurements of soil air permeability can be made using a device described
by DSMA (1983). Because the measurement technique for soil air permeability is still
under development, there is little guidance available for selecting the number and
location of measurement points. It has been observed in this study that soil
permeabilities near the substructure (i.e., at sites less than 0.5m, 1.5 ft., from the
building) in backfill material are generally higher than in the surrounding undisturbed
soil. But it is not known whether mitigation system interaction would be dominated by
this near-structure layer. Of course, multiple measurement locations could be useful,
but it requires considerable time to emplace a soil probe and conduct the measurement
(30 to 60 minutes). A suggested procedure involves driving a 1.3 cm (0.5 in.) O.D., 1.0
- 1.5 m (3-5 ft) long pipe into the soil, following a pilot hole, at approximately 0.5 -
1.5 m (1.5-5 ft) distance from the structure. A cylinder of compressed air is connected
to the pipe via a pressure gauge and flow meter. Based on the measured flow rate of
air into the soil at a pressure difference of 250 Pa (see Appendix D2 for sample data
log), the permeability can be calculated from:
K - 2.5 x 10*7 -r-
Pr
(4)
where:
K - permeability (cm2),
Q - flow rate (L/min),
P ¦ pressure (cm of water),
r - inside radius of probe (cm).
Measurement capabilities with this field device range from approximately 10~* to
10"4 cm3. The range of possible soil permeabilities is shown in Table 3.
Table 3: Range of Soil Permeabilities*
Soil lYPff
Permeability (cm3)
Clay
Gravel
Sandy clay
Silt
Sandy silt and gravel
Fine sand
Medium sand
io-u
5 x 10*"
5 x 10"10
5 x I0_#
5 x 10"*
5 x I0_#
5 x IO"4
~Tuma and Abdel-Hady (1973).
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At the same location as the permeability measurement, a soil grab sample should be
collected (see Appendix D5). In addition, at least one 1 kilogram sample of soil should
be obtained near each house from a depth at least 25 cm. This soil sample should be
sent to a laboratory for analysis and determination of emanating radium.' The
maximum radon concentration in soil gas for that soil can then be estimated from:
Coe - 0* (5)
where: - maximum radon concentration in soil gas, (pCi/L),
p - soil density, (g/cms),
e - emanating radium concentration, (pCi/g),
e ¦ soil porosity, [cm3 (air)/cm® (soil)j.
2., Radon in Water
In some houses, the radon concentrations in water are high enough that radon
coming out of solution can cause high indoor air radon concentrations. Previous
research has estimated that the ratio of domestic water radon concentrations and indoor
air concentrations is approximately 10,000 to 1 (Gesell and Pritchard, 1980; Nazaroff,
et al., J985c). Thus, a radon concentration in water of approximately 40,000 pCi/L or
higher may indicate that the water is an important source of radon, contributing
approximately 4 pCi/L to the indoor air concentrations.
Radon concentrations in water have a wide range. Water derived from surface or
most municipal supplies do not contain sufficient dissolved radon to warrant concern.
Most private well water supplies are also low in radon, however some individual wells
have been found to have concentrations above 10,000 pCi/L and upwards of 106 pCi/L
in rare cases {Nazaroff, et al., 1985c). Thus testing domestic water derived from a
private yell is a useful diagnostic procedure.
The most direct method for determining radon levels in housewater, Figure 3, is to
obtain two 1-liter samples of non-aerated water from the building supply that has not
been conditioned or filtered. An outdoor faucet is a good supply location. Hie faucet
is opened and water is allowed to flush for several minutes. Then the containers are
slowly filled with a short tube directed to the bottom of the container to avoid aeration
of the sample. After sealing and labeling, the containers should be sent within three
days to a facility for analysis by gamma spectrometry (see Appendix D6).
Due to the cost and difficulty in locating a facility for the water sample analysis,
an alternative technique is currently under study. In this procedure, the bathroom
shower of hot water is operated for IS minutes while the bathroom door is closed, large
gaps and cracks to the remainder of the house and outside are sealed, and any
mechanical ventilation is turned off. By using a simplified mass balance equation, a
crude estimate of the radon concentration in water is possible. Assuming that the
bathroom ventilation and other removal rates are negligible:
C(t)«5t + C(0) ((5)
^Emanating radium" is the radium concentration times the emanating fraction, the
portion of radon generated that reaches pore spaces and is available for transport
15
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where:
C(t)» Concentration in bathroom air at time t (pCi/L),
S ¦ Source rate (pCi/hr),
V ¦ Bathroom volume (liters),
t « Elapsed time of test (hr); for these purposes, t - 0.25 hr, and
C(o)« Concentration in bathroom air at t * 0 (pCi/L).
The source rate, S, is further defined as:
S - ECwW (7)
where:
E - Transfer coefficient (dimensionless); and approximately equal
to 0.9 (i.e., approximately 90% of radon in the water is
released to the air)
Cw » Concentration in water (pCi/L), and
W ¦ Water flow rate (liters/hr).
Substituting, Equation 1 can be solved for the radon concentration in water.
C . Y fCft) - Cfo)) (g)
* EWt v '
The necessary measurements for estimating the radon concentration in water are
therefore: W, shower head flow rate (using a measured container and stopwatch), V,
bathroom volume, C(o), grab sample of bathroom air radon concentration before
shower test, and C(t), grab sample of bathroom air radon concentration after 15-minute
shower operation. Once again, a calculated radon in water concentration of 40,000
pCi/L or higher suggests that treatment of the water may be necessary. Treatments can
include processes that filter the water through a charcoal column or aerate the water
(Becker and Lachajczyk, 1984). Alternatively, various methods of ventilation (with or
without heat recovery) can be employed to control the radon in room air after it has
come out of solution. After corrective action has been taken, follow-up measurements
of both water and building air should be made.
3. Radon flu* from Buildinm Materials
If indoor air radon concentrations are higher than can be reasonably explained by
levels in the water (water infrequently contributes significantly to air concentrations
exceeding 20 pCi/L), then action should be taken to control the dominant radon source
first. It is remotely possible that the building materials contain sufficient radionuclide
mineralization to result in high radon flux rates and corresponding high indoor radon
concentrations. The visual inspection during the building survey (Appendix B) should
identify suspected earth-based materials such as native stone, concrete, and aggregate,
as well as unusual construction features incorporating local geological formations (rock
outcroppings). See Figure 4.
If certain materials are judged to be potential sources or diagnostic tests do not
suggest other sources in the building, then a radon flux measurement on various
materials surfaces should be made (Appendix D4). In this measurement, a shallow pan
containing open charcoal canisters is temporarily sealed to the surface with duct seal or
a similar adhesive material for 24 to 48 hours. With this technique, it is possible to
obtain very high flux measurements when the pan is attached to a porous material
(concrete or cinder block) backed by high radon soil gas. This should not be
16
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interpreted as a building materials problem; rather it may be diffusive or convective
flow from high concentration radon gas in the block cells. Placing the pan on surfaces
above grade should alleviate some of this difficulty, except for open cell cinder or
concrete blocks that may contain high radon soil gas in the open cells even above
grade. The charcoal canisters are then analyzed and a flux rate, F, computed (pCi
m'hr"1). The material flux contribution to the indoor air radon levels can be estimated
by once again using a steady-state form of Equation 6:
C - SZi (9)
a
where:
C ¦ concentration in room (zone) air (pCi/L),
V * room (zone) volume (liters),
S - FA, and
F - radon flux rate (pCi m'hr"1),
A - material surface area (m2),
a - ventilation rate (hr"1).
Solving for the source rate necessary to produce guideline levels (4 pCi/L) of radon
in the indoor air and assuming a typical ventilation rate of O.S air changes per hour
(ACH) gives:
S - 2V (10)
or.
- 2pCiL*1hr*1 (11)
This formulation is interpreted to mean that building material radon flux may be a
problem if the. normalized source rate is approximately 2 pCi L"1hr"1 or higher.
Sealants, coating, or material removal may then be recommended. Follow-up
measurements of flux and heating season indoor air radon concentrations would be
made after any corrective action. However, as in the case of water contamination,
other sources are likely to dominate and should be addressed first.
B. Summarize Teat Data
Once all observations and measurements are completed, they should be compiled in
a way that clarifies the predominate mechanisms of radon entry, the extent of areas of
high radon concentrations in soil gas, the locations of likely entry points, and the most
suitable mitigation options. One practical method of summarizing is to prepare a "map"
of all the measurements as shown by the example in Figure 9. The data are referred to
by letter codes.
In this example, concentrations of radon in soil grab samples are highest along the
common foundation wall between the basement and the slab-on-grade. In addition, the
suspect radon entry points are the forced air heating registers in the slab-on-grade and
holes of unknown origin through the common foundation wail. Subslab ventilation
communication is poor across the slab-on-grade because there is no gravel underlying
the slab, while communication is good under the basement slab where then it gravel as
shown by data obtained using the vacuum system. With this system attached to point
IF7 (in the slab-on-grade area) little effect was observed at locations IW6, IW7, duct
under the stairs and at the forced air registers through the slab. When the vacuum was
17
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attached to point IF1, however, the observed pressure field (VAP) and air movement
(VT) at all basement floor holes and at many wall holes were significantly affected.
For this house, the data suggested the installation of a subsurface ventilation system
at the common wall which effectively ventilates the vertical space behind the wall and
the space below the basement slab near the common wall. The pressure field developed
by this system was observed at the far end (west) of the basement slab. In addition,
the penetrations of the common wall were sealed. These recommendations reduced
average basement radon concentrations from 217 ± 46 (standard deviation) pCi/L to 3.0
±1.1 pCi/L and first floor concentrations from 72 ± 22 pCi/L to 2.2 ± 0.9 pCi/L.
Figure 10 is a plot of the pre- and post-mitigation basement radon concentrations. The
two large radon peaks occurred during installation of the system when the subsurface
holes were opened through the slab and walls. These preliminary results show that by
identifying the areas of highest concentration and ventilation communication, a
localized system can be installed that may be more efficient and economical.
C. Selection of Mitigation Systems
This report makes a few inroads in the approach for selecting the appropriate
mitigation system. Which system to select for each situation is currently based on
experience, engineering judgment, and information collected during the diagnostic
measurements. By using a diagnostic "map" such as the one prepared in Figure 9,
selection and design of systems is facilitated since obvious entry points and high radon
areas are identified.
Unfortunately, the factors and their interrelationships affecting mitigation system
performance are still poorly understood. Therefore considerable ambiguity still remains
regarding decisions in certain situations for selecting one type of system over another
or in the sizing and placement of subsurface ventilation systems. Some situations may
require an initial system installation to know if the correct decision was made, which is
then followed by modifications and tests to re-evaluate system performance. These
empirical experiments should improve our understanding of the fundamental
mechanisms influencing radon entry and control and mitigation system performance.
As noted in the introduction, a detailed description of radon mitigation techniques
is beyond the scope of this paper. The following mitigation system descriptions are
keyed to the options listed in Figure 6. For a more detailed explanation of various
mitigation systems, the reader is referred to general discussions in Sanchez and
Henschel (1986), Fisk (1986), Ericson, et al.t (1984), Nitsckke, et al., (1985), Sachs and
Hernandez (1984), Scott and Findlay (1983), Turk, et a/., (1986) and the various DSMA
references listed in section V.
1 Crawlsnacas
As described in Figure 5, crawlspaces with high radon concentrations are generally
the easiest to mitigate and should be addressed first if the diagnostic "map" indicates a
radon problem. Earlier experimentation suggests that in homes where radon
concentrations in occupied spaces are higher than the guideline, crawlspaces should
receive mitigation if the crawlspace concentration is greater than or equal to 0.75 times
the concentrations in the occupied space or if it is greater than other substructure zone
concentrations. The factor of 0.7S allows for errors in measurement of zone air
concentrations.
Typically, crawlspace radon can be controlled by providing additional ventilation
through installing or enlarging openings cut into the exterior crawlspace walls. These
18
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openings will increase crawlspace ventilation and reduce the amount by which
crawlspaces are depressurized due to communication with the building interior.
Alternatively, a fan can be used to both ventilate and overpressurize the crawlspace.
Gaps and openings between the crawlspace and the living area should be sealed,
including any subfloor ducts. While sealing is probably most important in blocking the
entry of cold crawlspace air into the heated structure, it may also stop the entry of any
residual radon that remains in the crawlspace.
It may be that radon in the crawlspace has originated in other parts of the same
building and has simply been mixed into the crawlspace air by openings, gaps, leaks, or
ductwork. In these situations, radon levels in the crawlspace usually are lower than in
other substructure zones. It is also possible that, while the crawlspace is not the
dominant source of radon, it may be a secondary source sufficient to elevate indoor
levels in occupied zones above the recognized guideline. When this occurs, all
substructure zones contributing to the radon problem should be mitigated.
After a mitigation system has been installed, a 14-day average indoor air radon
concentration measurement should be made during the heating season. Other
measurements detailed in Figure 7 should also be made. If occupied space radon levels
remain high and crawlspace radon levels are high compared to other substructure zones,
then additional, more efficient crawlspace ventilation is recommended. However, if
crawlspace radon concentrations have been reduced to less than 0,75 times the higher-
than-guideline occupied space concentrations and less than other substructure zone
concentrations, then the crawlspace radon problem has probably been resolved while
contributions from other substructures zones will require attention.
2. Other Substructure Typw
Three other predominant substructure types are listed in Figure 5: basement with
poured foundation wall, basement with block foundation wall, and slab-on-grade.
There are other less frequently occurring substructure types, but the majority are a
hybrid of these three, plus a crawlspace. Possible mitigation options for radon control
in the appropriate substructure type are Indicated by number in Figure 5; the options
are described in Figure 6 along with certain qualifications as to their selection and
application. More details are given in die references (DSMA, 1979, 1980; Sanchez and
Henschel, 1986; Ericson, et al., 1984; Fisk, 1986; Henschel and Scott, 1986; Nazaroff, et
al., 1981; Nitschke, et al„ 1985; Sachs and Hernandez, 1984; Scott and Findlay, 1983;
Turk, et a/,, 1986).
Ventilation
The mitigation systems that are considered for installation are shown on Figure 6.
Options 10 and 11 are techniques for removing radon once it has entered the structure
and are limited by the practical amounts of ventilation air that can be added.
Therefore* these systems are useful only below certain maximum indoor radon levels.
These systems are also not recommended in houses where large air infiltration leakage
areas have been measured (suggesting high natural ventilation rates 21.5 ACH), since
the amount of additional ventilation required for successful radon control could be
prohibitive.
Subsurface Ventilation
Options 1 to 3, sump, floor drain, and French drain (floating slab) sealing are
almost always recommended when these are present, Subsurface ventilation via sumps
(option 3a), weeping tile (option 5), and sealed French drain ducts (option 3b) may be
J9
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useful for controlling the radon source where they can be practically employed as
collection and distribution points or manifolds. Other subsurface ventilation systems
(option 4) can be installed at the location of indicated radon entry points and "hot"
spots to minimize the cost of extensive installations, but can also be installed to
mitigate a more widespread or distributed radon problem if good subslab ventilation is
possible through an existing gravel underlayment. Both subsurface pressurization and
depressurization forms of subsurface ventilation have been demonstrated to be effective
in some houses. However, the differences between these two methods and any
potential long-term problems are not yet clearly understood, so recommendations
cannot be made for selecting between the two techniques.
Block Wall Ventilation
Hollow-block wall ventilation (option 6) should probably be limited to those
structures that have walls with few air leaks (gaps, cracks, holes) or with leaks that can
be easily closed; and have walls with enough pathways between the block cavities for
good ventilation communication.
Basement Overpressttrization
Basement overpressurization (option 9) is a relatively new technique that is
operating successfully in five Spokane, WA residences (Turk, et al„ 1986). It should
still be considered an experimental technique that is to be installed in buildings with
tight basements, preferably with no forced air furnace, and with no combustion
appliances in upper occupied floors.
Sealing of Cracks and Holes
Sealing of cracks and holes (option 8) may be effective in improving the
performance of other techniques, but may have limited impact by itself on radon levels
where there are many inaccessible cracks and openings.
Mitigation techniques that were not considered as options because of lack of
testing, impracticality, or ineffectiveness are: substructure surface coatings, removal of
contaminated soil from around a substructure, and indoor air cleaning devices.
P. Poat-mltlgfltlon Svrtem Evaluation and OntlmlMttan
Following installation of the radon control systems, observations and measurements
to monitor system performance should be made (Figure 7). Measurements of
temperatures, air flow rates, and differential pressures in ducts and pipes help to define
the operating characteristics and efficiency of heat recovery ventilators, subsurface
ventilation systems, and basement pressurization systems. Air flows are measured with
a pitot tube or hot wire anemometer traverse of the duct or pipe. In addition, radon
concentrations monitored by grab samples in the exhaust stream of subsurface
ventilation indicate the effectiveness of removal strategies on depletion of the radon
source. Periodic inspections are necessary to monitor the integrity of sealants, fillers,
bonding agents; connections and physical attachments; noise and vibration of fans and
blowers; accumulation of moisture and condensation; and leaks and bypasses in ducts
and pipes. Discussions with building occupants and owners should also identify other
system weakness such as noise, convenience, and appearance.
The mapping survey of radon grab samples, pressure differences, and air flow
movement should be repeated to determine the extent of system effects on radon
sources and near-substructure pressure fields. Before commencing follow-up
20
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measurements a minimum 12-hour delay is necessary to allow stabilization of the
indoor building environment. Follow-up average indoor air radon concentrations are
also measured for a minimum of two days during the heating season. While this is a
very short measurement period, higher-than-guideline radon levels indicate that the
mitigation system is not operating properly and that further action is required. Lower-
than-guideline levels are substantiated by subsequent measurements of at least 14-day
duration. In general, system tuning is preferable when indoor concentrations have been
reduced below 2 pCi/L since it is possible that the system is grossly overdesigned and
that system complexity, energy requirements, operating costs, or noise levels can be
substantially reduced. This is an iterative process involving small modifications
followed by monitoring that minimize the installed system until indoor radon levels just
begin to show an increase. At this point, the operating conditions of the system are
returned to the next higher level of operation so that the system is not operating at the
margin of failure.
If indoor radon concentrations remain above the guideline after system installation,
then the follow-up grab sample survey may assist in deciding on the next step. For
source control systems, the installed system is not controlling radon entry as designed if:
1) grab samples from suspected entry points are still greater than room concentrations,
or 2) the pressure field at those points is insufficient (air moving out of entry point).
In these cases, the system performance should be boosted by increasing pressure
differences or flow rates delivered by the fan or by installing additional ventilation
points (for a subsurface ventilation system) near the high radon areas and remaining
uncontrolled entry points. If the grab samples are less than or equal to room air
concentrations, and if flow and pressure measurements indicate a suitably developed
pressure field, then more attention should be directed to radon entering from other
substructures in the building. Alternatively, the installation of a completely different
type of radon control system may be necessary.
After the 2-day measurements indicate that indoor radon levels are successfully
reduced to below the guideline, a longer 14-day average measurement of room air
concentrations during the heating season should be conducted. If indoor levels
measured during this period are once again higher than guidelines, additional mitigation
should be undertaken either in the form of modifications to existing systems,
installation of alternative systems, or addressing other substructures within the building.
Long-term radon levels below the guideline suggest that the system is operating
successfully. However, the building owners and occupants should perform periodic
system maintenance (oiling bearings, changing filters, etc.) and conduct long-term (one
month minimum) follow-up indoor air radon concentration measurements annually
during the heating season.
E. Application of Procedure 1m 14 New Jersey Houim
At the writing of this report, the diagnostic procedures are currently being used to
select appropriate radon abatement measures in 12 of the 14 houses in the LBL/Oak
Ridge/Princeton research project. Modifications to these procedures are being
evaluated and will be applied to the two remaining control homes near the conclusion
of the project. Maps of the type in Figure 9 have been, or are being, prepared for
each of the 12 homes and mitigation systems installed in at least eight of the homes.
Preliminary data from the first three homes that have been mitigated indicate that
the diagnostic procedures provided information necessary to installing localized and
successful subsurface ventilation systems (see Figure 10).
21
-------
IV. SUMMARY
A preliminary set of diagnostic procedures has been developed for identifying the
sources of indoor radon problems and selecting systems for controlling radon. In the
homes where the recommended remedial measures have been installed, based on the
diagnostic measurements, radon concentrations 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 the 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 progress in research still underway. Additional
data and observations are being made that may support, augment, or in some cases
invalidate, some of the conclusions discussed here.
Other diagnostic techniques and tools under investigation in this and other studies
include: use of tracer gases to quantify entrainment of building air into subsurface
ventilation systems; creating flow and pressure maps for hollow block foundation walls;
attempting to quantify and apportion subsurface ventilation from below slabs and from
within block walls; estimating outside air ventilation that enters along the soil/house
line; and development of a radon "sniffer" with faster recovery time between samples
taken from test holes, entry points, and indoor air. Another new method will attempt
to challenge an installed mitigation system by using a depressurization fan to gradually
increase substructure depressurization and thereby determine the system failure point.
22
-------
V. REFERENCES
Becker, A.P. and Lachajczyk, T.M., (1984), Evaluation of Waterborne Radon Impact on
Indoor Air Quality and Assessment of Control Options, Report EPA-600/7-84-093,
NTIS PB84-246404 (Research Triangle Park, NC: US EPA).
DSMA ACRES, (1979), Report on Investigation and Implementation of Remedial
Measures for the Radiation Reduction and Radioactive Decontamination of Elliot
Lake, Ontario, Dilworth, Secord, Meagher, and Associates, Limited and ACRES
Consulting Services Limited, (Ottawa, Canada: Atomic Energy Control Board).
DSMA ACRES, (1980), Report on Investigation and Implementation of Remedial
Measures for the Radiation Reduction and Radioactive Decontamination of Elliot
Lake, Ontario, Dilworth, Secord, Meagher, and Associates, Limited and ACRES
Consulting Services Limited, (Ottawa, Canada: Atomic Energy Control Board).
DSMA Atcon Ltd., (1983), Review of Existing Instrumentation and Evaluation of
Possibilities for Research and Development of Instrumentation to Determine Future
Levels of Radon at a Proposed Building Site, Report INFO-0096, (Ottawa, Canada:
Atomic Energy Control Board).
DSMA Atcon Ltd., (1985), A Computer Study of Soil Gas Movement into Buildings,
Report 1389/1333, (Ottawa, Canada: Department of Health and Welfare).
Ericson, S.O., Schmied, H., and Clavensjo, B,, (1984), "Modified Technology in New
Constructions, and Cost Effective Remedial Action in Existing Structures, to
Prevent Infiltration of Soil Gas Carrying Radon", in Indoor Air, Proceedings of the
3rd International Conference on Indoor Air Quality and Climate, Vol 5, pp. 153-
158, (Stockholm: Swedish Council for Building Research).
Fisk, W.J., (1986), "Research Review: Indoor Air Quality Techniques", Report LBL-
21557 and in Proceedings of IAQ '86, Managing Indoor Air for Health and Energy
Conservation, pp. 568-583 (Atlanta, GA: ASHRAE).
Gesell, T.F. and Prichard, H.M., (1980), "Hie Contribution of Radon in Tap Water to
Indoor Radon Concentrations", in Proceedings of the Symposium on the Natural
Radiation Environment III, Vol 2, U.S. Department of Energy, CONF-780422, pp.
1347-1363, (Springfield, VA: NTIS).
Henschel, D.B., and Scott, A.G., (1986), "The EPA Program to Demonstrate Mitigation
Measures for Indoor Radon: Initial Results", in Indoor Radon, Proceedings of an
APCA International Specialty Conference, pp. 110-121, (Pittsburgh, PA: Air
Pollution Control Association).
Nazaroff, W.W., Boegel, M.L., Hollowell, C.D., and Roseme, G.D., (1981), "The Use of
Mechanical Ventilation with Heat Recovery for Controlling Radon and Radon
Daughter Concentrations in Houses", Atmospheric Environment, 15, pp. 263-270.
Nazaroff, W.W., Feustel, H., Nero, A.V., Revzan, K.L., Grimsrud, D.T., Essling,
M.A., and Toohey, R.E., (1985a), "Radon Transport into a Detached One-story
House with a Basement", Atmospheric Environment, 19, pp. 31-46.
23
-------
Nazaroff, W.W., Lewis, S.R., Doyle, S.M., Moed, B.A., and Nero, A.V., (1985b),
"Experiments on Pollutant Transport from Soil into Residential Buildings by
Pressure-Driven Air Flow", Report LBL-18374, Lawrence Berkeley Laboratory, to
be published in Environmental Science and Technology.
Nazaroff, W.W., Doyle, S.M., Nero, A.V., and Sextro, R.G., (1985c), "Potable Water as
a Source of Airborne Radon-222 in U.S. Dwellings: A Review and Assessment",
Report LBL-18154, Lawrence Berkeley Laboratory, to be published in Health
Physics.
Nazaroff, W.W., Moed, B.A., Sextro, R.G., Revzan, K..L., and Nero, A.V., (1986),
Factors Influencing Soil as a Source of Indoor Radon: A Framework for
Geographically Assessing Radon Source Potentials, Report LBL-20645, Lawrence
Berkeley Laboratory, Berkeley, CA.
Nero, A.V., and Nazaroff, W.W., (1984), "Characterising the Source of Radon Indoors",
Radiation Protection Dosimetry 7, pp. 23-29.
Nitschke, I.A., Traynor, G.W., Wadach, J.B., Clarkin, M.E., and Clarke, W.A., (1985),
Indoor Air Quality, Infiltration and Ventilation in Residential Buildings, W.S.
Fleming and Associates, NYSERDA Report 85-10, (Albany, NY: New York State
Energy Research and Development Authority).
Ronca-Battista, M., Magno, P., and Nyberg, P., (1986), Interim Protocols for Screening
and Followup Radon and Radon Decay Product Measurements, Office of Radiation
Programs, Report EPA-520/1-86-014, NTIS PB86-215258 (Washington, DC: US
EPA).
Sachs, K.M. and Hernandez, T.L., (1984), "Residential Radon Control by Subslab
Ventilation", In Proceedings of the 77th Annual Air Pollution Control Association
Meeting, San Francisco. CA, Paper No. 84-35.4, (Pittsburgh, PA: Air Pollution
Control Association).
Sanchez, D.C.and Henschel, D.B., (1986), Radon Reduction Techniques for Detached
Houses, Technical Guidance. Report EPA-625/5-86-019 (Research Triangle Park,
NC: US EPA).
Scott, A.G. and Findlay, W.O., (1983), Demonstration of Remedial Techniques Against
Radon in Houses on Florida Phosphate Lands, Report EPA-S20/5-83-009, NTIS
PBS4-156157 (Washington, DC:US EPA).
Sherman, M.H. and Grimsrud, D.T., (1980), "Measurement of Infiltration Using Fan
Pressurization and Weather Data", Report LBL-10852 and in Proceedings of First
Air Infiltration Centre Conference on Air Infiltration Instrumentation and Measuring
Techniques, pp. 277-322 (Berkshire, UK: Air Infiltration Centre).
Tuma, J.J., and Abdel-Hady, M., (1973), Engineering Soil Mechanics, p. 102,
(Englewood Cliffs, NJ: Prentice-Hall).
Turk, B.H., Prill, R.J., Fisk, W.J., Grimsrud, D.T., Moed, B.A., and Sextro, R.G.,
(1986), "Radon and Remedial Action in Spokane River Valley Residences", Report
LBL-21399 and in Proceedings of 79th Annual Meeting of the Air Pollution Control
Association, Minneapoljs, MN, Paper No. 86-43.2 (Pittsburgh, PA: Air Pollution
Control Association).
24
-------
Figure 1
General Plan for Radon Control
Problem Diagnosis
• Measure heating season indoor radon concentrations
• Evaluate non-soil sources
• 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
• Monitor indoor air concentrations
• Measure mitigation system operating parameters
Post-Mitigation Evaluation
Successful
(improve system efficiency)
Unsuccessful
modify system —
or
install additional options
XBL 871-8920
25
-------
Figure 2
Problem (Hagnosift
Replicated, 7-Day Average Radon Concentration in Indoor Air
Heating Seaaon Meaaurementa
t L 1
Level* ^ 4 pCi/L on ail iivtDie floors - Mo Action I levela • 4 pCi/L on any iivaeie floor
1 j
Conduct Building Survey
. r~ ~
j^Figi«2Aj Non-Soit Sources—^Figure^
CharwMrlM Structure and Identify Entry Points
i ) Conduct Vteuef Inepocttow
- Complete forme <«*e and floor plana. eievationa. nouemg aurveya. occupant questionnaire)
- Probe ttkoiy entry pomta (wan or floor cracks and tolas, meaonry interface. block wail top and hMa) uamg »tiH w*e,
acrawdrivar, and amok* tgoea
2.) Onto Sample Indoor Air under Natural Condition*
Collect alpha •onottawn can grao tampiae undar eiiatmg natural conouona from each umqua budding tone (garage. 2nd floor,
tat noor. baaement. crewtapece. aiaoon.prado areas).
3.) drab Sample indoor Air under Meeftenteal Oepreeeurtsetlon
CoNaet grao sampiea uamg alpha acwwmatww ceae from w»ety entry points and venoua euMmg tonea (trua sampling oouid Da
rapaatod 2*3 days attar ma firat eampang to document the vanaodtty in ma technique due to environmental laeiora or sampling
procedure)
Oepreeaunae houae uamg blower door to -10 Pa m aubatrueture tor > 90 mm. (may not eauao repreaentative dtatnbuaon of ftn
throughout houae)
a) grab aempte of indoor atr from aacn separately defined room or tone at imd«he room concentration
ere net likely antry pemts. moae with concentraeona - 2-5 X room concentration are poaiibta antry pomta. and thoae with concen-
trators > 3 X room conccniraaon are iHtety entry pomta.
4.i QuaWy Mr Movumrt nam UMy Cntry NM
Oepreaaunie nouaa to -30 Fa m substructure to characterise air movement from eon to heuae through entry pomta uamg
Chemical smoke
Cheek flow at suOetructure cracks. hoiea or joints m aiaba or waaa
tope of Hock weiia
other potential entry pomta: eumpe. drama, ahower and todet beaea. aerviea antrcnoaa and panetranona
8.) Conduct Blower Door Teata to: ( .thewholehouaa
- meeaure tne equMeiam leakage area of: I • aubavuetura only
\ • auperatruetura oiey
• ) Otieiva VonWodon Cowntiinleedon WMMn Woeli WeNe and ienoalh Slebe:
- uamg Mgh vacuum (2 m: M m. waMr) and high flew <170 m'h'1; 10Q ctml Newer, depreaaunaa eubeleb region and meaeure
preaiure dropa and datarmma air movamant at imaiy antry pomta and drdea taat hoiea. mcmomg thoae m wane
- attach Mower te Mock weae and check for air leake «n the wella and me ament of tne mduead ventaetion at cradta and hoiea
and dnNad teat hoiea.
7) Obeerve Iffeot of ApplUwice Operation:
' uamg mcromenemaiar datermme additional dapreaaunieaon of aubatructura due to appliance operation (Oryer. fumece imoai*
anaa. fireplaee- wood atove. aahauet fan) by ayieang appliance en/off for approi. 20 eyefea
AdOtaonai oapreaauniaoon < s Fa
Take eorractwa ecaon •
I I Conduei tan Tmm (apttonafy
}
Aeomontf depreaaunxeMn • 9 Pa
I
——— No action
- if Subeurfeee. or weeping Me ventaaaon may be conaidered aa mitigation opaona. conckwt near^nouaa ion air pemnoabaty
teat, and aoii Ra teat
X8t V\ Wt«
To
Figure 5
26
-------
Figure 3
Radon in Water
Local Well Water?
Yes
Direct
method
Test water
1
Alternative
method
t
Water sample analysis
i—'—,
Cw < 40,000 pCi/L
No water
treatment necessary
Cw > 40,000 pCi/L
(replicated)
Bath air grab sample
Operate Bath Shower 15 Minutes
to Obtain Closed Room Air Sample
I
(Cflnal bath ~ ^initial bath) * ^bath (L)
w ** F.how.r(L/hr) X 0.9 X t(hr)
_L
Cw > 40,000 pCi/L
cw < 40,000 pCi/L
Mitigation options:
- Aerate
- Filter
- Options: 10
I 11
14-day average indoor
radon concentration measurement
l
Figure 6
Indoor levels > 4 pCi/L
Indoor levels < 4 pCi/L
No additional corrective action
• Annual follow-up water tests by occupant
• Periodic system maintenance by occupant
XBL 871*8917
27
-------
Figure 4
Radon Flux from Building Materials
Unusual construction features incorporating local geological formations (rock outcropping) or
large amounts of earth-based construction materials (thermal mass, native stone surfaces)?
No
Yes
Measure Rn flux
Flux rate (pCi/m2-hr) X material area (m2)
7 7n
hOUM*1-'
<2 pCi/L-hr
1
No materials
mitigation action
necessary
>2 pCi/L-hr
Mitigation options:
- Remove or seal material
- Options: 10
11
See
Figure 6
Materials mitigation
implemented
14-day average indoor
radon concentration measurement
Indoor levels > 4 pCi/L
and flux <2 pCi/L - hr.
Indoor levels > 4 pCi/L
and flux > 2 pCi/L-hr
Indoor levels < 4 pCi/L - No additional action
• Annual long-term follow-up indoor air measure-
ments using a-track film by occupant
• Periodic mitigation system maintenance by occu-
pant
XBL 871-8918
28
-------
Figure 5
Section of MMgalion Systems
After a careful revww of the substructure)*), itemization al potential entry points, grab sample and air Sow
mapping, and occupant mwments on operation of certain apptisnces. a irrigation pfen should be developed
H sboukl atoms control of radon tor each house starting with one substructure type before mowing to the
next subsbudtaa type. Crawfspaces (if they exist) are typicaly the simplest type to mitigate and work should
begin here U the diagnosis so indicates. ^
No
*
Other predominant substructure
types or <
1
Yes
_L
See
Figure 6
As Mealed by mapping and inspection survey.
MMgaiwi options: 1 7,
2 9
3 10
4 1t
5
As MaWty mapping and inspection survey.
Hnjrtinn options: t 6
2 7
3 8
4 *
5 10
11
See
Figures
ShbaaQmk
As indicated by supping and inspection survey.
legation options:
4 m "
heating system ducting may require
seatngfrom occupied spaces and rerouting through attic.
S In addMon. subslab healing system ducting may require
seeing from occupied space and rerouting through attic.
Crawrispaoe concentration <
0.75 x occupied space - and lass
than other substmdure zone con-
Indoor levels > 4 pCi/L
- Additional mitigation
10
See
Figure 8
Figure 7
Crawlspace concentration i»
0 75 x occupied space concentra-
tion or greater than ottier sub-
Structure lone concentrations
*
testa! 0.09 m* (t untformly distributed venti-
lation/9 m* <100 ft1) floor area or us tat fan sized
for S ACH to overpressurize to ~10 Pa. Install
thermal insulation. Seal between crawlspace
and structure, including return air ducts.
I
14-day average indoor radon concentration
Indoor levels < 4 pCi/l - No additional action
• Annual long-term lolknv-up indoor air measure-
ments using o-track film by occupant
• Periodic mitigation system maintenance by occu-
pant
XBL871 89t5
-------
Figure 6
Mitigation Options
f) Sump sealing - active and inactive sumps
2) Floor drain seating - if not water-trapped
3) a) Sump sealing and ventilation - active or inactive sumps with or without drain tile
b} French drain sealing and ventilation
4) Subsurface ventilation
A) Exterior fiLiMStiSL
• If homeowner prefers exterior Gravel under floor slab
• No landscaping Interference • Central ventilation point
• No utilities interference every 45 m2 (500 ft*)
• Perimeter wall entry points No gravel
• Locate near entry points
Exhaust ventilation - soil impermeable, soil Ra high
Supply ventilation - soil permeable, soil Ra low
Drill series of small inspection holes in Door {1 cm; 3/8 in. diam.) and walls (0.0 cm; 1/4 in. diam.) to
determine extent of pressure field.
5) Weeping tile ventilation • Where tile is accessible
• Where tile is proximate to entry points
6) Wall ventilation - only if sealing successfully limits fan sue to < 500 m^"1 (300 cfm) (smoke tubes at
inspection holes to verify extent of ventilation)
7) Root crack sealing • Where majority o< cracks accessible
• Where cracks localized - no network of cracks
• Floating slab gap if no indication of water entry
8) Wall cracks and hole sealing • Where majority of openings are accessible
• Where openings are localized
' Only If blocks are open cat!
9) Basement overpressurization (special option)
• Where leakage of basement membrane is small
• Where sealing of exterior and interior membranes is possible
• Where if heating system is forced air, ductwork is tight and no forced air furnace
registers present in basement
• Where 1st floor vented combustion devices are not present
Use blower door on basement to estimate approximate fan size: should be < 1 ACH delivery to achieve
5 Pa over-pressure
10) Balanced ventilation with heat recovery (special option)
Multiple substructures:
• If indoor concentrations > 4 pCi/L, < 20 pCi/L on all floors:
- Ventilate all floors with 5 X original ventilation to < 2 ACH (new total)
Basement only :
• If basement concentrations < 80 pCi/L
- Ventilate only basement where original basement ventilation < 0.2 ACH to new total < 3.5 ACH
• System must be installed to match existing finish
11} Balanced ventilation w/out heat recovery (special option)
• Unoccupied basements sealed and thermally insulated from ocoupied space.
• In basement install 0.09 m* (i ft3) uniformly distributed vents to the outside per 4.0 m2 (50 ft2} Door area
or instaH fan sized to S ACH to overpressurize substructure to 10 Pa
Options not considered here : Coatings
Soli removal
Air cleaning
30
-------
Figure 7
Port MMgtlon Evaluation
Manure Temperatures and dWaranM pressures In intfi»ad duett. pipes; nil and building Marior air tows
developed by fen in duels and pipes: radon concentrations In exhaust air streams.
Observe: Integrity of saatanli. Mars, and bonding agents. Noise and WbraHon of fans and Mowers Inspect
lor tasks and bypasses in a* systems Correct N necessary
Repeat grab sample mapping survey and measure average indoor air concentrations for minimum ol two
Indoor
Re tine system operakon unW room a*
concentrations just begin to show an increase-
then boost system operating parameters
air
To
> 2 < 4 pCi/L - No hit
long-term Mow-up indoor air
by occupant («-tracfc fikn)
Indoor
Flows Appro* 50% Block-oH Subsurface
options: Ventilation Points
I g Mitigation options:
Grab
by occupant
See
Figure 6
auMnent at Maty entry points
3.«, S,6.9»
»y blower appro*. S0%
Mitigation 3
See
Figure 6
' Figure 7
Return lo
top of page
-------
Figure 8
Distribution of Structure Effective Leakage Areas
Whole building (ELAJ «a+b+c+e+f+g
Superstructure (ELAp) -a+b+c+d
Substructure (ELAb) * d + e + f + g
Substructure ceiling (ELAC) ¦ d
Substructure walls/floor (ELAf) » e + f + g
XBL871 8921
32
I
-------
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-------
APPENDIX A
RADON DIAGNOSTIC
CHECKLIST
NAME
BOUSE ID
DATE
NON-SOILS: U Water Sample Fcoa Outalda Faucet _____
[] Surface Flux Meaauraoenta: [1 Wall _
[] floor
SOILS:
(] Soli Air Permeability
tl Soil 6*a Grab Samplea
[1 Cora Sample ____
BUILDING STRUCTURE: [] Vlaual Inapeetion, Complete Survey Form
(1 Natural Condition Scintillation Call Orab Saaplea
[1
[]
Laval 2
Laval 1
(1 Laval 0; Each Unique Zona
[] Ambient Air Saapla; Outalda Air T«ap ___
Hind Spa ad
Inalda Air Teeqp __
(1 CLoaad Bathsooa, U (Ua. Shower Operation
(1 Drill Taat Bolaa la Floora/Walla
(] Start Data Lowin* on 1 Mia. Interval:
(1 Synchrooiae All Cloeka
tl Shut Oft Caubustioa AppLlancea
(] Mechanical Depreeaurlaation
t] Seiatlllatlaa Call Orab Sanplaa (to - lOFa)
(] Subatruetura Fined Wall Cavltlaa __
(j Subatruetura Block Hall Calla ______
[ j Subatruetura Wall. Floor Cracka _____
U Subatruetura Karris* HiHiiUan ___
C) Subatruetura Taat Bolaa _________
(j natural Condition Saapla Losatlona __
[] Air Movaaaat Saoka Tuba (to - 30 FA)
(] Subatruetura Craaka, Bolaa (Particularly Walla)
11 Ivp* ot lloei tt*U» _________________
(I Taat Belaa
tl Interior Soil Line _______________
tl latwaaa Fleori
[| Othar
11 HA taata:
(1 Wbola Bouaa (Open to Subatruatura)
() Subatruetura Only ___________
tl Supar Structure 0aly ____________
tl 3 Slower Taat _____________________
tl Depreaeurlse Attie: With tl Calibrated Blower
(1 Whole Bouaa Attia Fan
(1 Cyele Fan and Haaaura Baaaaent AF "
(1 Appliaaea Cyelln* • Subatruatura AF Maaaureaeata aa
Appllancea ara Cycled On/Off S Tinea
tl Clothaa Dryer _____________________
tl lahauat Faaa ____________________
tJ Furnace: () Ceefcuetioo Air Only _______
tl tm Oaly ____________
tl Both of Above ____________
11 Whole Bouaa Vacuus Claaaar ______________
tl Jecm-Air
OTHER MEASUREMENTS: (] Sub-Slab AT Mapplnc With Induetrial Vaeuua
tl Tbrou»b Floor __________
t l through Hall* __________
Optional tl Soil Llna SF» Injection Mala Depreaauritedi
Oaa Mir an to SaBple:[] Subatruetura Kooai Air
(1 Block Wall Call* _______
OTHBl TASKS: _____________
A - 1
-------
APPENDIX £
MOON 80USCB DIAGNOSIS
BUILDI»3 SURVEY
HAKE:
ADBUS8:
FHOttt MO:
BOOSE INSPECTED
MSB
arrival tine _
DEPARTURE TIMS
sum* TBCVXCXAIB:
I, BASIC CHARACTER! ZAIIOM Of BBHDXN8 AMD SDMHUCIURK
SUA
1. Ag« at Iwum
2. Baaia luiUUas Cooatructiods
Extarioe Matastala ' "
lotariox Matariala
3. Eartb-baaad MUiai HUciil* U tba b»114W " daaoribai
*. Ooaaatla wattr *ou*aa:
a. Mnlaiyal tuxCae*
b. Municipal wtU
a. Ob-ait* wall
4. ©tba* -
3. Building istiltcafeion as ¦aebanieai vantilatioa
• ¦ building (hall - laakr, Mdw«t*i tijht
b. waatbaeiaatian - 4wU, waatAacateip, «ta.
8 WWi#» aspaaara a. ba«irr toaaat ..
b. UtbtiyKoedad » *»b** »•«** Wildin»»
a. opm tarcain, so buildina* naasb? .
axbauat faaa: a. «bola hou«« attic £«na .
b. kltabaa tana _
«, bath fam " ' . _ .
4. otfeac . - . ,
a. ftaguancr at aaa
otbae nacbanical vaneilation _«»«.
-------
S. Existing Radon Mitigation Measures
typ«
Where __________________
When
7. Locale - DeaeEiption: ________
8. Iftniaual outdoor activitiaa: faxa
oonatruotion
factorial
haavr traffie
Subatructure
1. Full baaaoMBt (baaaoent extende beneath entire house)
2. Full crawlapsce (crewlspaes extendi beneath antira house)
3. Full slab on grade (alab estenda banaath antira houaa)
~ . Bouse alavatad abova ground on piara
9. Combination baaaiant and erawlapaoa (X of aaob)
6. Coobination baaaaant and alab on grada (Z ot aaeb)
7, Combination erawlapeca and slab on grada (X ot aaeb)
S. Coaibination orawlaproa, baaaaant, and alab on grada (X of aaob)
9. Otbar — apeeity
Qeennanta
1. Rumbac of occupants __________________________ Wunber of Children _____________
2. (lumber of aaokara _______________________ Type of awaking ____________
and frequency
Alf 9HUVT
1. Conplainta about the air (atuffineaa, odora, reapiratory problaaw, watery eyes, daopnaaa, ate.)
2. Are there any indications of aotsture probleas, humidity or eondenaation (water narks, nolda,
condensation, eta.)?
Whan
Rote: cooplete floorplan with approximate dlaenslona and attaeb.
B - 2
-------
ZZ. BUIUZMOS WITH FULL OR PARTIAL BASEMENTS
luMwnt u*i|ii occupied, recreation, itoru*, other
Baaeaent walla conatruoted of:
a. hollow bleak (concrete, cinder)
b. bleak planuaa: £111 ad, unfilled
top bleak fill ad or aolld: yea, no
a. aolld bleak (concrete, cinder)
d. eondition of bleak aortar Jointa: (teed, aediua, poor)
a. poured conerete
f. efcbar aatariala — apeeify: ______________________________
aatlaata length and width of unplanned crecka: _______________
h. interior wall coatinja: paint, aaalaat, other:
1. exterior wall eoatins: parget, aaalaat, inaulation (type ^
Baaaaant finish:
a. completely vmfiniahed baaeaent, wall, and floor have set been oovarad with paneling. carpet
tile, ate.:
b.
ftaiiy finiahed baaeaent - apeeify finleh aatariala:
a.
partially finiahed baaaaant — apeeify:
Baai
a.
Ment floor aatariala:
eontalna unpaved aaetien (i.e., expoaed aoil) — apeeify site at
id location ef unpaved araa(a):
b.
a.
poured concrete travel layer underneath
bleak, brick, or atone - apeeify
<1
- aneeify
a.
daaeribe floor eraeka and holea through baaaaant floor
f.
t\Q*T enwMinf - BOaCifT _____
Baaeaent floor depth below grade - front _____ tear aide 1 tide 2
Baaeaent aeeaaa:
a. door to firat fleer of houae
b. deer to garage
a. door to outaide
d. ether - apeeify '
Door between baa anient and firat floor la:
a. no anally or frequently open
b. normally cloaed
Condition of door aeal between baaeaent and firat floor - deaeribe (leaky, tight, ate.):
B - 3
-------
9. Baaement window(a) — spacify:
a. number of windows
b. typa:
e. condition:
d. total axaa:
10. Baaaiaaat wall-to-floor joint
a. aatimata total length and average width of Joint:
b. indieata if fillad or aaalad with a gasket of rubbar, ityrofoam, or othar natariala - specify
matariala:
e. aooaaaibility - daaoriba:
11. Baaaawnt floor drain:
a. standard drain(a) - location:
b. f ranch drain - daaeriba length, width, dapth
o. othar specify:
d. connaots to • weeping (drainage) tila system beneath floor - spacify source of information
(visual inspection, homeowner consent, building plan, other);
e. connaots to a sump
i. connaots to a eanitary aawer
S. contains a water trap
h. floor drain water trap ia full of water:
e.
et time of inspection
b.
elwaya
c.
usually
d.
infrequently
e.
ineuffioient information for a
f.
specify source of information:
12. Basement sump(s) (othar than above): location: __
a. connected to weeping (drainage) tile system beneath basement floor -- specify source of
information:
b. water trap is present between sump and weeping (drainage) tile system — specify source of
information:
c. wall or floor of sump contains no bottom, cracks or other penetrations to soil — describe:
d. Joint or other leakage peth ia preaent at Junction between eump and basesMnt floor - describe
sump
containa water:
a.
at time of inapection
b.
always
c.
usually
d.
infrequently
e.
insufficient information for at
f.
apeoify source of information:
B - 4
-------
pip* or opening through which water antara aump ia occluded fay water:
a. at time of inapection
b. always
o. usually
d. Infrequently
a. insufficient information for answer
f. ipacify aourca of information:
f. Contains functioning sump pump:
13. Focead air heating system ductwork: oondition or aaal - daacriba: supply air:
baaament haatad: a. intantionally return ais:
b. incidentally
14. Basement alaotrieal aarvica:
a. alactrical outlata -- number __________ (surface or rseassed)
b. breaker/fuae box •• location ______________________________
13. Penetrations between basement and first floor:
• . wlunfelM!
b. alsetrical:
c. ductwork:
d. other:
16. Bypasses or chases to attic (describe location and ais*):
17. Floor material type, accessibility to flooring, etc.
18. Is osulking or sealing of holes and openings b*tw**n substructure and upper floors possible from:
a. basement
b. living area
B - 5
-------
III. buildings with full or partial cramlspaces
Crawlspace uaaga: stores*, other
Crawlspace walla constructed of:
a. hollow block (concrete, cindar)
block planuna: filled, unfilled
top blocka filled: yea, no
b. aolid block (concrete, oinder)
c. condition of mortar jointa: (good, medium, poor)
d. poured concrete
e. other __________________________________________——
f. estimate length and width of unplanned creeks
g. interior well coatings: paint, sealant, other
h. exterior wall coating: parget, sealant, insulation (type
Crawlspace floor materials
a. open soil
b. poured concrete
gravel layer underneath
o. block, brick, or stone - specify ____________________
d. plastic aheet
condition: _______________________________________
e. other materials - specify: ______________________
f. deacribe floor cracks and holee through crawlspace floor ___
g. floor covering - specify: '
Crawlspace floor depth below grede ______________________
Describe crawlspace access ______________________________
condition __________
Crawlspace vents:
a. number _________________________
b. location
e. cross-sectional area
d. obstruction of vents (soil, plants, snow, intentional) _______
Crawlspace wall-to-floor joint:
a, estimate Length and width of crack
b, indicate if sealed with gasee of rubber, styrofoem, ether - specify
c, accessibility - describe ________________________
Crawlspace contains:
a. standard drain(s) - location '
b. franch drain - describe length, width, depth _______________
c. sunp
d. connect to: weeping tile system _______________________
a. sanitary sewer
b. weter trap (trap filled, empty)
B - 6
-------
9. Forced air haatinf ayatan ductwork: condition and aaal - daacriba
10. Crawlapaca haatad: a. intantlonally
b. inoidantally
11. Crawlapaca alaetrical aarvica:
a. alactrioal outlata - nunbar _________________
b. braakar/fuaa box - location _________________
12. Daacriba tha intarfaca batwaan crawlapaca, baaaoant, and alab.
13. Fanatrationa batwaan crawlapaca and £irat floor:
a. plumb ins:
b. alactrioal:
o. ductwork;
d. othar:
1*. Bypaaaaa or obaaaa to attio:
IS. Caulking faaaibla from: a. baaaoant
b. living rooca
B - 7
-------
IV. BUILDINGS WITH FULL OR PARTIAL SLAB FLOORS
Slab uaage: occupied, recreation, atorage, other:
Slab rocm(a) finish:
a. completely unfinished, walla and floor hava not b««n covarad with paneling, carpet, tila, ate.
b. Cully finiahed - ¦ pacify finish matetiala
e. partially finiihad - specify
Slab floor materials:
a. pourad concrete
b. block, brlek, or itona - specify
o. othar materials - specify
d. fill matariala under alab: land, gravel, packed soil, unknown
aourea of information
a. daaoriba floor cracks and ho las through slab floor: _________________
f. floor covering " apacify "
Elevation of alab relative to surrounding aoil (e.g., on trade, 8" above grade, eto.):
la alab perimeter insulated or covered: yea, no
Slab area access to raawinder o." bouse - describe ___________
normally: open, closed
Slab wall-to-floor Joint:
a. estimate length and width if eraek
b. indicate if sealed with gasket of rubber, styrofoam, other - specify
c. accessibility - describe
Slab drainage:
a. floor drain - describe _________________________
b. drain tila system beneath slab or around perimeter - describe ___
c. source of information _________________________
Forced air heating systasa ductwork:
a. above alab condition and aeal - deacribe
b. below alab:
a. length and location ___________________________
b. materials
Slab area electrical service:
a. electrical outlets - number _____________________
b. breaker/fuse box - location ______________________
Deacribe the interface between alab, baaament, and erawlapace:
B - 8
-------
11. Fanatrationa batwaan slab araa and occupiad zonaa:
a. plunbins
b. alactrical ____________________
e. duetwork ______________________
d. othar _______________________
12. Bypaaaaa ox ehaaaa to afetie: _____________
B - 9
-------
V. SUBSTRUCTURE SERVICE BOLES AMD PENETRATIONS
(Hot# on floor plan)
Cooplata table to daacriba all aarvica panatratlona (i.e., pipaa on conduit foe watar, gaa alactricity, or
imr) through aubatructura floor* and walla. Indicate on floor plan.
Daacription of aarvica, aixa
location, aenaaalbllltv
Ezarapla:
watar, 3/4"
ooppai pipa,
through floor,
accasaibla.
Slza of crack or sap around sarvica and
tvea and condition of aaal
Exampla: Approx. 1/6"
gap around circuafaranca
of pipa with scaling
atycofoam gaskat.
B - 10
-------
VI. Appliances
Major appli.anc«i located in subatruetuxa (crawlspace, slab-on-grada, basement)
Location Description
Appliance 81ft. SMI) (Tual free. style. mtnUm)
Furnaoe
Water Haatar
Air Conditionar
Clothea Dryer
Exhaust Fana
Othar:
Foroad air duct/plenum aaala * daaeriba
Combustion Appliances: combustion air supplied (yes, no)
B - 11
-------
n
i
SITE PLAN
h
SITE PLAN
>
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-------
SITE ELEVATION
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FTTTm ra
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CO S3
Sc*fni tit^e >
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retocojfapuy
SITE ELEVATION
-------
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4
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FLOOR PLAN
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-------
RADON OAS SAMPLING LOG
APPENDIX D1
Occupant N*»e louae ID#
Technician °*6*
LUCAS CELL MEASUMMDITS
Sample Nuabar
1
a
3
Lucaa Call ID#
Taata eince laat background
(new baakgrowd after 10 taata)
Background rata (cta/aln)
Samolina:
(] Indoor [] Outdoor
() Indoor (] Oitdoor
t) Indoor [] Outdoor
Saapla Location
I
/
'
Analvala
I
- MXKMUM 30 MX*. DtUtf -
Counting laatruaaat
Data/Tlaa atartad
Ilapaad Delay Tlaa |
/
1
Count to 1000, atop at Mt ainuta, 10 oinuta Nasi
mm'
Tlaa Stop
Total Count*
' Slapaad Counting Tiaa (Bin)
Concentration
Sanpla Ruofaar
*
s
lani
•
Lucaa Call ID#
Taata alnaa laat background
(new background attar 10 taata)
Background rata (ata/aU)
Sanmllni:
Saapla Location
() Indoor () Outdoor
U Indoor (1 Outdoor
[] Indoor tl Outdoor
/
USS
/
/
Analvala
- M
HUM 30 MM. DSLAX -
Counting Inatnaaat
Data/Tlaa atartad
Slapaad Dalay Tlaa (alnutaa)
Tiaa Stop
Total Caunta
Slapaad Counting Tlaa (ain)
/
Count to MOO, at
1
s
!
i
t
D - 1
-------
APPENDIX D2
Soil. P6gNA6AS*n-ry soevey
House *•©..
HAM* -- T60»MIO»M
AOOfcftt ' Ofc-TB ___
jMAfLr mo. | 1
z
»
LOtMtOM II
H 4t :
Ai< TCDfeMMi :
osscAimoM
0«PTH MOHTUM TSXTUt*
Qgfru
MOitn/<( TB'rruc.c
oepm
———-
moivucc "nrxrute
0 OfcV Q PI***
Qhoar 0«AN»y
a»«.T OUMW
I _ a _a
a o«w o P"»j«
~ Moisr a iamiw
~ tuftT a coa<*c
~ a
~ oav a fim6
3 Mxr a samow
~ v/Jtr q
~ a .
tOllr WU
UOCAt &#U- l-O.II ||
1
PUttOUC
i
z
t
1
z
* II .
i.
i
fto-nwwvrva i.fc.
KarmMwnut i.
UMIHM
i.
&
X
fwui un
K cm*"
CCKIOWTl
NO. |
s
<»
toonoit {
Ai< t6vrsmtu» -
4«e imfvnwur :
4-C T&Mcu*rve*:
&*sc*i*not4
pmu
MoiVTvt* Trent**
Qgyru
Motvrvitui iTmiu
perm
»*I*TVIU 1VY1VLI
a °** O Pins
Q MOI«T 0
a w«rr q comm.
~ o(ty a Pim*
a Motfr Q sMaoy
a VMBT a GOAMl
a n - O II
a fed-y a
0 Mour o Wtav
a a c«mm
a a
soil.
«*4 wmifkit
p«iLM\rAibii.iT-y
fiutsaui
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R-ovm *«t* j
K tml
csMMrim
c »/«>¦
D - 2
-------
APPENDIX D3
Occupant Nioa
Addraaa
Ttehnieian:
Monitorin* Fariod
LBL/BFA FAM TEST DATA SBEZT
_____ Sous* ID Mo.
Blower Door S/H or Oaacrlp.
Data
BUIUZKO DIMENSIONS
Floor Araa
Calling >al(bt ,
Voluao
mat floor
_(ft*>
.(ft3)
.(ft®)
Floor Araa
Calltnc lil|U
Voliao
Total Aroa __________________
Total VoIum
Ovarall Baltht of OnupM Floors ______
laaluda baa Moot or attla on It if oesupiad
Brmmmmu. data
jft1)
.(ft1)
_
(ft2)
.(ft3)
.(ft3)
Outdoor:
Indoor:
Tasparatura _
Wind Spaad _
Taaparatuxat
o*r
Ralativo Humidity:
Twin Parmat.ra (labia on back)
Shielding Claaa
Tarraln Claaa
louso A F
(flUlll 1
SSL
UL
i&L
UL
ilL
UL
m.
UL
UL.
1AL
o-iao
or I DOM
I
I
I
±
120-730
UEa
or
TIST DATA
Koto: Uaa "Urn"
data for calculation* if
differ sot.
'¦ Loa atlas
Fa* Configuration (11.10,3)
Carralatlao
Standard trror
AAiUL
JUU
«ci (* r«)
ad Ad (90 Fa)
BROOK OOmiTIOM
Flraplaaa Saalad _____
Moodauva Saalad _______
Inaluda araa (la1) of ottao* aaalad
Ci—mtai
Dryar Vant __
Combustion Alt
Wiwit Fan*
Furnasa Flua
LaafcMa ea.tft.in. (Tabla on back)
>. { **7^ }
{
it
zJ.
It
>
in
XHFORTAMT! FItOT LXORSi Matar laatar
lam anas Barkoloy laboratory l-tl-U
Fumaaa
D - 3
-------
TABLE 1
TERRAIN PARAMETERS
Class
I
II
III
IV
V
y a
0.10 1.30
0.15
0.20
1.00
0.8S
0.25 0.67
0.35 0.47
Description
Ocean or other body of water with at
least 5 km of unrestricted expanse
Flat terrain with some isolated
obstacles (e.g., buildings or trees
well separated from each other)
Rural areas with low buildings,
trees, etc.
Urban, industrial or forest areas
Center of large city (e.g. Manhattan)
SHIELDING COEFFICIENTS
Shielding Class
I
II
III
IV
V
C
0.324
0.285
0.240
0.185
0.102
Description
No obstructions or local shielding
whatsoever
Light local shielding with few
obstructions
Moderate local shielding, some
obstructions within two house heights
Heavy shielding, obstructions around
Very heavy shielding, large obstruction
surrounding perimeter within two house
ueights
TABLE OF R AND X VALUES
House Condition
House Type
Loose
Windows & Doors
(R.x)
Average
Windows and Doors
(R,X)
Tight
Windows and Doors
(R,X)
1 story (slab) .3,.3
1 story (baeement .5,0
or crawl)
2 story (slab) .2,.2
2 story (basement ,4,0
or crawl)
.4,.4
.66,0
.3,.3
.5,0
.5, .5
.8,0
.4,.4
.6,0
D - 4
-------
BUILD IMG MATERIALS SAMPLING LOB
MANE MOUSE ID# _
ADORESS TECHNICIAN
SURFACE *
Location
(Note on Floor Plan)
Deploy: Date
Tim
a
i
Ul
lenwi Data
Tiae
Distance Fro*
Halt
Indies
Distance Fro* Floor
Depth Below Grade
Canisters: #1
#2
Descriptions: Material
Surface Finish
Surface Types:
Wall 1. 2, 3
Floor 1, 2, 3
Other 1, 2, 3
M
a
-------
Page of
SOIL SAMPLE IPG
l
-------
Pag* of
UMCT MHPtES '-0C
1.0.
hUrm Technician
Data
Collection: Date:
liw:
Faucet Location
Water Supply
fumt
0
1
8/29/86
£
n
§
£!
a
o\
-------
TECHNICAL REPORT DATA
(Please read Intouetiont on the reverse before completing)
1. REPORT NO. 2.
EPA-600/8-88-084
3. RECIPIENT'S ACCESSION NO.
4. TITLE ANO SUBTITLE
Preliminary Diagnostic Procedures for Radon Control
B. REPORT DATE
June 1988
8. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
B. H. Turk, J. Harrison, R. J. Prill, and
R.G. Sextro
B. PERFORMING ORGANIZATION REPORT NO.
LBL-23089
B. PERFORMING ORGANIZATION NAME ANO AOORSSS
Lawrence Berkeley Laboratory
University of California
Berkeley, California 94720
10. PROGRAM ^lImKnT Kl6.
W. CflNTiACT/'aAAKiT RiifiJ " 1 ""
EPA IAG DW89931876-01-1;
DOE DE-AC03-76SF00098
12. SPONSORING AOENCY NAMS ANO ADDRESS
EPA, Office of Research and Development
Air and Energy Engineering Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OP REPORT ANO PERIOD COVERED
Final- 5/fifi - 4/87
14. SPONSORING AGENCY COOK
EPA/600A3
is.supplementary notes AE pr0ject officer is David C. Sanchez, Mail Drop 54, 919/
541-2979.
^o. abstract rep0rt describes analytical procedures for diagnosing radon entry me-
chanisms into buildings. These diagnostic methods are generally based on the pre-
mise that pressure-driven flow of radon-bearing soil gas into buildings is the most
significant source of radon in houses with elevated concentrations, although proce-
dures to determine the contributions of other potential sources (e.g., building ma-
terials and potable water) to indoor airborne concentrations are also included. Flow-
charts are presented that develop a logical sequence of events in the diagnostic pro-
cess, including problem diagnosis, selection and implementation of mitigation sys-
tems, and post-mitigation evaluation. The initial problem assessment procedures
rely on an organized set of measurements to characterize the structure, the sur-
rounding soil, and the likely entry pathways from the soil into the building. The mea-
surement procedures, described in detail, include radon grab sampling under both
naturally and mechanically depressurized conditions, visual and instrumental ana-
lyses of air movement at various substructure locations, 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.
17. KEY WORDS AND DOCUMENT ANALYSIS
I. DESCRIPTORS
b.lOCNTIPIf RS/OPSN ENDED TERMS
c. COSATI Field/Group
Pollution Construction Mater-
Radon ials
Diagnosis Potable Water
Analyzing Measurement
Soils Sampling
Residential Buildings
Pollution Control
Stationary Sources
Soil Gas
13B
07B 13 C
06E 08H
14B 14G
08G, 08M
13M
Release to Public
IS. SICURITY CLASS (fhk Alport)'
Unclassified
at. 6# JUfflir™
64
20. SECURITY CLASS (1%iipage)
Unclassified
ai. ^Ricd
SPA Form saao.1 (*•71)
------- |