United States
                      Environmental Protection
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
                      Research and Development
EPA/600/S8-88/084 Nov. 1 988
x°/EPA           Project  Summary
                      Preliminary  Diagnostic
                      Procedures  for  Radon  Control

                      B. H. Turk, J. Harrison, R. J. Prill, and R. G. Sextro
                       Analytical procedures for diagnosing
                      radon entry mechanisms into buildings
                      are  described.  These  diagnostic
                      methods are  generally based on the
                      premise that  pressure-driven  flow of
                      radon-bearing soil gas into buildings is
                      the most significant source of radon in
                      houses with elevated concentrations,
                      although procedures  to determine the
                      contributions of other potential sources
                      (e.g., building  materials  and  potable
                      water) to indoor airborne concentrations
                      are  also  included.  Flowcharts are
                      presented that develop a logical se-
                      quence of events in the diagnostic pro-
                      cess,  including problem diagnosis,
                      selection and implementation of mitiga-
                      tion systems, and post-mitigation evalua-
                      tion. The initial problem assessment pro-
                      cedures rely  on an organized set of
                      measurements to characterize the struc-
                      ture, the surrounding  soil, and the like-
                      ly entry pathways from the soil into the
                      building. The measurement procedures,
                      described in detail, include radon grab
                      sampling  under  both naturally  and
                      mechanically depressurized conditions,
                      visual and instrumental analyses of air
                      movement at various substructure loca-
                      tions, building leakage area tests, and
                      soil characterization   methods.  Post-
                      mitigation evaluation  procedures are
                      also described. Samples of various data
                      forms and test logs are provided.
                       This Project Summary was developed
                      by  EPA's Air and Energy Engineering
                      Research Laboratory, Research Triangle
                      Park, NC, to announce key findings of the
                      research project that is fully documented
                      in a separate report of the same title (see
                      Project Report ordering information at

                       With the discovery of high indoor radon
                      (Rn-222) concentrations in a significant
number of houses since the late 1970s, it
has become important to develop a better
understanding of the mechanisms of radon
movement  into  and  accumulation in
buildings and suitable methods for control-
ling or eliminating the accumulations. In
general, earlier research has found that the
most significant source of indoor radon is
the soil surrounding the building shell from
which radon migrates  into the  building,
transported by the pressure-driven flow of
soil gas. Factors influencing the radon en-
try rate include indoor-outdoor air temper-
ature differences, wind loading,  soil
characteristics, construction details of the
building superstructure and substructure,
and the coupling between the soil and the
  To further investigate radon control
techniques,  the U. S. Environmental  Pro-
tection Agency (EPA), the Department of
Energy (DOE), and the New Jersey Depart-
ment of Environmental Protection (NJDEP)
funded an intensive study in 14 northern
New Jersey houses. The research was con-
ducted  by the  Lawrence  Berkeley
Laboratory (LBL) in seven houses and col-
laboratively  by  Oak Ridge  National
Laboratory and Princeton University in the
remaining seven houses. The  following
overall objectives were established for the

  - Extend the understanding of the fun-
    damentals of soil gas flow and radon
    entry  into buildings and improve the
    basic knowledge  of factors that in-
    fluence the entry rate.
  - Refine  and  develop analysis  pro-
    cedures for diagnosing radon entry
    mechanisms and selecting appropriate
    control systems.
  - Develop and  demonstrate  practical
    radon  mitigation techniques  for
    selected  basement/crawl  space

  The research plan to meet the above ob-
jectives had four main  components:  1)
house   and   site   characterization
measurements, 2) baseline and continuous
monitoring of environmental and building
parameters, 3)  diagnostic  procedure
development, and 4) installation and opera-
tion of selected mitigation techniques.

Diagnostic Procedures
  This report focuses primarily on the se-
cond  objective:  i.e.,  the preliminary
development of  diagnostic procedures.
Diagnostic procedures are defined here as
organized and logical measurements, tests,
and  observations that are necessary for
identifying the  specific means by which
radon enters and accumulates in a par-
ticular structure. These procedures should
point the way to a suitable system or techni-
que  for controlling indoor radon  levels.
These procedures may also be applied as
follow-up measurements, tests, and obser-
vations useful  in optimizing mitigation
system performance. This development ef-
fort builds on the previous, on-going, and
generally unpublished work of others, in-
cluding Scott, Tappan, Ericson, and Bren-
nan,  as well as on  the basic scientific
understanding   developed by Nazaroff,
Nero, Tanner, and others. This report pro-
vides a format for refinement, reduction and
interpretation of the  measurements and
observations necessary for selecting an ap-
propriately  designed, effective,  and
economical system for controlling indoor
radon  concentrations  in  single-family
detached  houses.   Table 1  lists the
diagnostic  research  measurements and
procedures discussed in this  report.
   The premise for many of the diagnostic
procedures developed and discussed here
is that the  pressure-driven flow of radon
bearing  soil gas is the most significant
source of radon in houses with elevated
concentrations. However, other potential
sources  of  radon,  such  as  water and
 building materials are also included in the
 diagnostic  procedures. Figure 1  outlines
 the mitigation process framework govern-
 ing the use of diagnostic measurements.
   The procedures described here rely on
 individual site-specific observations and
 short term  measurements  of  air  flow,
 pressure differentials, radon concentrations
 and near-building material characteristics.
 The measurements are then used to iden-
 tify primary radon sources (water, building
 materials, soil) and most probable radon
 entry points and mechanisms. Tools and in-
 struments listed in Table 2 are necessary
 to conduct the  diagnostic  procedures
 discussed  in  this  report.   The  report
Table 1.    Project Measurements and Procedures
           >  Visual Inspection of House

           •  Alpha Scintillation Cell Radon Grab Samples

           '  Sub-slab and Wall Air Flow Communication Tests

           <  Air Infiltration Leakage Tests

           '  Appliance Depressurization Effects

           <  Soil Characterization

           <  Radon in Water

           <  Radon Flux from Building Materials
                                 Problem Diagnosis

           • Measure heating season indoor radon concentrations

           • Evaluate non-soil sources

           9 Characterize structure and soils and identify entry points
           Selection and Implementation of Mitigation Systems

           • Consider results of diagnostic measurements

           • Review options for mitigation

           • Develop and implement mitigation plan
                              Post-Mitigation Evaluation

           • Monitor indoor air concentrations

           • Measure mitigation system operating parameters
  — ~ —   (Improve System Efficiency)
 Figure  1.    General plan for radon control
assumes  that the  reader has prior ex-
perience with flow and pressure measur-
ing devices,  and alpha particle counting
techniques. The full report describes the
         (Modify System]  —
     (Install Additional Options)
diagnostic procedures forms used for data
recording and  a sample application  of
diagnostics in a house studied as part of
the aforementioned comprehensive study.

Table 2.    Instruments and Equipment
Radon Grab Sampling:
Air Leakage and Flow
Soils Characterization:
Inspection Equipment:
Alpha scintillation cells
Portable photomultiplier tube counting station
Hand pump with sample tube and 0.8 cm filter
Compressed air or nitrogen for cell flushing
Vacuum pump for evacuating cells (70 cm, 27 in. Hg vacuum)

Calibrated-flow blower door (6800 m3fr', 4000 cfm @ 5 Pa)
Pitot tubes (electronic or liquid-filled manometers: 1-50 kPa)
Hot wire anemometer (with temperature sensing element)
Smoke tubes
Industrial vacuum cleaner (170 m3fr', 700 cfm @ 2 m HzO pressure)
1.5 m (5 ft) flow sections of: 7.6 cm (3 in.) PVC with coupler
                         15 cm (6 in.) galvanized duct
Non-toxic tracer gas (SFe, Freon-12)
Tracer gas detection instrument

Soil core and auger samplers
3/4 in. reversible electric drill
Soil air permeability device
Sliding hammers
Various diameter drill bits, include some
       attached 1.5 m (5 ft) long extensions
1.5 m (5 ft) long probe pipes

Stiff wires
Telescoping mirrors
Portable gamma spectrometer
Fiber optics scope

3/8 in. variable-speed hand drill
Masonry bits
1/2 in. hammer drill
Impact bits
Pocket flashlights
Hand sledge
Pry bar
Pipe wrench
Locking pliers
Adjustable wrenches
Portable lights
Step ladders
Long blade screwdriver

Inspection hole plugs
Epoxy-based mortar patch or hydraulic cement
Duct tape
Duct seal
0.3,  0.6,  1 cm (1/8, 1/4, 3/8 in.) diameter tubing
Various-sized hypodermic needles
Plastic film
Thermometers: electronic and mercury-filled glass
Silicone sealant
have been  developed for identifying the
sources of  indoor radon problems and
selecting systems for controlling radon. In
houses where the recommended remedial
measures have been installed, based on
the diagnostic measurements, radon con-
centrations have fallen below the guideline
of 4 pCi/L However, a rigorous process for
selecting successful, optimized systems
has not yet been developed for widespread
use by technicians and contractors.

  Three new,  and  largely  unvalidated
techniques are presented that may assist
in determining contributions to indoor radon
levels from the domestic water supply and
building materials and the approximate
distribution of air infiltration leakage  area
in a structure. This document reports on
progress in  research still underway. Addi-
tional  data  and  observations are being
made  that may support, augment, or in
some cases invalidate, some of the conclu-
sions discussed here.
  Other diagnostic techniques and tools
under invesitgation in this and other studies
include: use of tracer gases to quantify en-
trainment of building air into subsurface
ventilation  systems;  creating  flow  and
pressure maps for hollow block foundation
walls; quantifying and apportioning subsur-
face ventilation from below slabs and  from
within  block walls; estimating  outside air
ventilation that enters along the soil/house
interface; and development of a radon "snif-
fer" with faster  recovery time between
samples taken from test holes, entry points,
and indoor air. Another new method will at-
tempt to challenge an installed mitigation
system by using a depressurization fan to
gradually increase substructure depressuri-
zation  and thereby determine the system
failure point.
  The report  discusses details of the
various diagnostic methods, techniques,
and procedures currently under develop-
ment,  and provides in flowchart form a
logical sequence of steps that will guide the
reader  through  the  measurement  and
evaluation mitigation process.  The  em-
phasis of this system of diagnosis is for
                    research purposes and is intended to serve
                    as the basis for development of approaches
                    for general commercial applications.
                      The report provides a house-specific ex-
                    ample of the above diagnostic procedures
                    with  the purpose of demonstrating  and
                    evaluating their utility in the mitigation  pro-
                    cess.  Preliminary diagnostic procedures

     B. Turk, J. Harrison, R. Prill, and R. Sextro are with the University of California,
      Berkeley, CA 94720.
     David C. Sanchez is the EPA Project Officer (see below).
     The complete report, entitled "Preliminary Diagnostic Procedures for Radon
      Control," (Order No. PB 88-225 115/AS; Cost: $14.95, subject to change)
      will be available only from:
            National Technical Information Service
            5285 Port Royal Road
            Springfield, VA22161
            Telephone: 703-487-4650
     The EPA Project Officer can be contacted at:
            Air and Energy Engineering Research Laboratory
            U.S. Environmental Protection Agency
            Research Triangle Park, NC 27711
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