United States                   EPA~600/9-89-Q57
Environmental Protection
A9encv                      June 1989
Research and


APRIL 13-14, 1987
Prepared for
 Office of Radiation Programs
Prepared by
Air and Energy Engineering Research
Research Triangle Park NC 27711


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     Diagnostic approaches offer improved evaluations of radon-related
indoor air quality problems.  An informed solution involves knowledge of the
building, the building site and the interaction of radon sources with the
living space.  The diagnostics are applicable in four phases of the
mitigation process.  The first phase consists of diagnostics which assess
the radon problem.  The second phase involves the pre-mitigation
diagnostics.  From this phase of the diagnostics a suitable mitigation
approach must be chosen.  Third are the important diagnostics that check the
performance of the radon mitigation solution.  Finally,  the fourth phase of
radon diagnostics determines if the radon problem has been solved and that
guideline radon concentrations have not been exceeded over the different
seasonal conditions experienced.

     A consensus of current knowledge on important radon diagnostic
techniques and how they may be best applied are the result of a two-day
Radon Diagnostics Workshop sponsored by the U.S. EPA held at Princeton
University, April 13-14, 1987-  That knowledge is summarized, placing the
various radon diagnostic techniques in perspective.

                              TABLE OF CONTENTS
Abstract                                                                 ii

Preface                                                                  iv

A.  WORKSHOP SUMMARIES                                                    1

    I.      RADON PROBLEM ASSESSMENT    M. Mardis,  Chairman               1

    II.     PRE-MITIGATION DIAGNOSTICS -  L. M. Hubbard, Chairman          5


    IV.     POST MITIGATION DIAGNOSTICS - B. Henschel, Chairman          14

B.  WORKSHOP PRESENTATIONS                                               18

    General Considerations Related to Radon Diagnostics                  19
      J. Tell Tappan

    Use of Vehicle-Mounted Radiological Equipment in the Diagnosis of    28
    Houses with Elevated Levels of Radon and its Short-Lived Progeny
      C.S. Dudney, B.A. Berven, T.G. Matthews and A.R. Hawthorne

    Soil Characterization for Radon Availability and Transport           35
      C. Kuntz

    Overview of Selecting Radon Mitigation Methods                       43
      T. Brennan

    Interim Report on Diagnostic Procedures for Radon Control            56
      B.H. Turk, J. Harrison, R.J. Prill and R.G. Sextro

    Guaranteed Radon Remediation Through Simplified Diagnostics          72
      D. Saum and M. Messing

    Follow-up Diagnostics - How Well Does the Mitigation Work            77
    and Does it Meet the Guidelines?
      K.J. Gadsby, D.T. Harrje, L.M. Hubbard and C.A. Decker

C.  WORKSHOP DISCUSSIONS - Phase I - pg 81, Phase II-pg 101,             80
                           Phase Ill-pg 109 & Phase IV-pg 118

D.  ADDITIONAL MATERIAL - Supplemental Radon Diagnostics Infor-         125
      Mation from the Piedmont Study plus diagnostic Master List

E.  REFERENCES                                                          151

F.  ATTENDEES                                                           161



   The scope and objectives of the Radon Diagnostics Workshop were to gain
an improved prospective, and to develop guidelines on the usefulness and
range of applicability of different diagnostic techniques.  To categorize
state-of-the-art diagnostic methods, and to treat questions the diagnostic
methods seek to answer regarding radon emination, transport, entry and
indoor distribution, four phases of radon diagnostics were highlighted in
the Workshop.  These phases are:
   I.   Radon Problem Assessment Diagnostics:  radon source strength and
        location, house characteristics, and house occupancy

   II.  Pre-Mitigation Diagnostics:  selecting the best mitigation system
        for the particular building taking into account radon "hotspots"
        and other special conditions particularly as related to the house

   III. Mitigation Installation Diagnostics:  used during installation of
        mitigation systems to assure proper operation.

   IV.  Post Mitigation Diagnostics:  assurance that the radon guidelines
        have been met and that the mitigation system is adjusted properly.
   The background  of  the attendees was varied, but much of their
 experiences with radon has been a direct result of the U.S. EPA, DOE and
 state programs  attempting to understand and mitigate radon problems in
 primarily  residential buildings.  Examples of that experience come from
 states all over the U.S., as well as Canada.

   A critical review  of the effectiveness of current diagnostic procedures
 was part of the Workshop agenda.  Panel discussions focused upon the
 various diagnostic methods with emphasis given to questions such as:

        a)   How good is the rationale for the diagnostic measurement?
        b)   How easy is the diagnostic procedure?
        c)   What  resources and expenses are required to implement the
        d)   What  information can be obtained from using the diagnostics?

     The format of the workshop proceedings begins with summaries of each
 of•the four phases of radon diagnostics.  The summaries provide a quick
 overview of the topics discussed and conclusions reached in the
 discussions, and refer the reader to more detailed treatment of the
 various topics  in  the text that follows.  The Workshop Presentations are a
 part of that text  together with the Workshop Discussions.

    The emphasis on diagnostics in radon troubled homes is a quest for
additional knowledge as to the severity of the problem, the approach that
may be used for solution of the problem and to evaluate the way the
solution is working out.  It was clear in the Workshop discussions that
such diagnostics are absolutely necessary in some homes but many of the
procedures are not cost effective in the homes that are simpler to
mitigate.  Anticipating possible radon problems at the house design phase
is likely to prove more cost effective than extensive soil probing to
quantify the radon problem potential for the individual building lot.
Measurements to determine radon levels for the majority of our homes are
generally recommended.  In those areas of high incidence of homes with
radon levels greater than the EPA guidelines and/or regions where very
high house radon levels have been observed, every homeowner should check
their house for radon concentration levels.

   Where radon problems exist it is important to evaluate exactly what
should be done.  In homes with concrete basement floor slabs the
diagnostic approach receiving wide acceptance is to check for
communication under the slab.  Subslab suction is commonly used to remove
the radon gas via a fan and piping that exhaust to the outside, but
diagnostics are necessary to make certain that suction extends over the
entire slab.  That openings through slab or basement walls need only be a
few square centimeters, points out that just sealing the
basement/crawlspace may not be enough, and that active or passive radon
venting may be needed.  A knowledge of how the house and its equipment
function with respect to providing the pressure differences that drive the
radon flow is necessary if the correct measures are to be taken.

   Diagnostics after mitigation devices are in place are necessary to
insure that the job has been done correctly.  An informed homeowner or
private testing agency  is recommended for these checks so as to avoid the
conflict of interest of a mitigator justifying his solution has been

   The Workshop treats  these radon diagnostic subjects in depth, looking
at the pros and cons of diagnosing the radon troubled house before, during
and after mitigation.  The techniques described are evolving rapidly in a
field where discoveries are being made daily.  However, many of the
diagnostic approaches may already be viewed as "standard", while many
others are in the process of being finalized.

   The principal conclusions of the discussions of each phase of the
diagnostics are given in the following summaries.

Radon Diagnostics Workshop,  1987.   Phase I Summary


Phase I.  - SUMMARY


1.   Gamma Scans

   •  The National Uranium Resource Evaluation (NURE overflight data)

would most likely be useful in identifying large land areas which would

exhibit a higher probability of indoor radon problems.   However,  because

of geological differences, and local hotspots, low readings should not be

interpreted as an absence of a radon problem.

   •  Local gamma surveys such as "scan vans"  or "on foot" methods may

prove less useful than NURE global surveys because of the limited

coverage.  The van is limited by road access,  while on foot surveys may be

limited by time constraints.

   •  Isolated hotspots and depth of the radon sources place limitations

on the  information available from the various gamma surveys.

2.  Soil Gas Measurements

   •  Soil Gas Measurements are another approach to accessing  the

probability of local  indoor radon problems.   High radon  levels in  the  soil

gas  (thousands of pCi/L), combined with soil  information (permeability in

particular), can indicate the potential1 for elevated indoor levels.

However, the number of measurements necessary to identify  the  radon

problem potential for a particular construction lot could  cost more  than

building radon prevention into a house.  Hotspots may be missed  in the

survey, even with a large number of samples.

   •  The variability of soil gas measurements  (i.e., a  10  to  100  fold


Radon Diagnostics Workshop, 1987.  Phase I Summary

difference in levels within tens of feet) is a function of location (e.g.,

if the measurement is taken directly over a rock fracture or a few feet

away with impermeable soil),  and may be a function of soil parameters

including moisture and type of clay or sand.

   •  Soil gas measurements seem to correlate with indoor radon values in

areas where there is very homogeneous soil (Florida) but soil gas and

indoor data do not seem to correlate well in areas with highly non-

homo gene ous soils.

   •  Soil gas measurements could be of use in identifying areas of

concern on a regional, or  "housing development" scale but not on a single

lot basis.  This could be  confounded in an area of variable soil types.

   •  In the comparison of soil gas measuring methods, grab samples are

preferred to alpha track and charcoal canister.  Further protocol

development is needed for  soil gas measurements (i.e., where, when, how

deep, and what type  of measurement to make).  Direct measurements of soil

gas and soil permeability  are preferred.  Samples from at least one meter

depth to avoid atmospheric dilution were recommended.  Quality assurance

and quality control  procedures need to be developed.

   •  A cost benefit analysis needs to be performed to access the

value/risk of using  soil gas measurements versus building radon resistant

houses on a regional and single  lot basis.  General feeling was that there

would be a negative  cost benefit when used on a single lot basis.

   •  Delineation of Terms for discussion of this topic area include:

   Radon production  = radium decay rate
   Radon entry efficiency  = indoor radon/soil gas contribution to

Radon Diagnostics Uorkshop, 1987 -  Phase ±

     Indoor radon level x 100.
   Radon availability — Rn cone. In pores x sean migration distance.
   Mean migration distance = f (soil characteristics and radon decay

3.  Problem House Identification

   •  The geological and the J5URE data may be useful to focus indoor

screenlng/iaeasureisent surveys.  The only way to be sure about a house  is

to make a "closed house* measurement.

   *  Useful surveys could be based on prediction models and/or the "Fan

Out" approach around discovery houses (where "fan out" means the use of

high level houses as the centers for studing nearby hoses).

   All screening surveys should base design considerations on:

        sampling during winter "closed house" seasons
        areas with known elevated indoor levels
        sampling more frequently in areas with nsore elevated levels, i.e.,
          sample every house  in areas where a. large percentage of  the
          houses sampled resulted in levels 4 pCi/L.

4,  Questionnaires

   •  Preliminary screening questionnaires are useful for research house

selection and as an opportunity for mitigators to address whether

confirmation measurements have been performed to substantiate the  Indoor

levels.  They may also ask questions which would provide basic information

on imajor entry  routes, basic  construction type, etc.

   •  The preliminary questionnaire could identify activities which the

homeowner could carry out to  address the need for professional mitlgEtlor.


   •  Pre-mitigation questionnaires and visual Inspections  are perhaps the

Radon Diagnostics'Workshop,  1987.  Phase I Summary

diagnostician's primary and most useful tools.  Homeowners should be

consulted, but information could be suspect unless the homeowner can

produce blueprints or pictures.

   •  The length of questionnaires and the questions asked tend to be a

function  of the experience of the diagnostician/mitigator and the

construction  type.  Typical entry routes, if  identified with early

questions, might preempt other unnecessary questions or diagnostics.

5.  Research  Needs

   •  We  seem to have a sufficient understanding of the major factors

influencing radon entry and typical entry routes in some construction

types to  be effective mitigators in those types.  (For example, basements

and perhaps slab-on-grades where subslab ventilation systems have proven

highly  effective when reasonable communication is present under the slab.)

   •  There is a need for research in other construction types and

combinations  of building types.  Basic research concerning radon

production, transport and entry  into buildings; so that we may better

understand phenomenon we are dealing with and perhaps develop even better

mitigation and prevention techniques.

   •  More research is needed  in modeling and prediction/correlations

between geological factors and indoor levels.

Radon Diagnostics Workshop, 1987.  Phase II Summary

Phase II.  -  SUMMARY

          PRE-MITIGATION DIAGNOSTICS -  L. M. Hubbard, Chairman

1.   Diagnostic goals of researchers and mitigators.

   •  During discussions of diagnostics techniques in general it is

important to be aware that diagnostic measurements appropriate for

research needs are  in many instances different than those appropriate for

use by mitigators.  Researchers use pre-mitigation diagnostics to further

their understanding of the basic mechanisms for radon transport into

building structures.  Some of the research has been directed towards

developing specific diagnostic techniques that are most useful for

mitigators to use.  The mitigator on the other hand is interested in being

able to mitigate  a  house successfully with a minimum of time invested in

diagnostic measurements.   The Phase II discussions attempted to separate

these two approaches to diagnostics.

2.  Mitigator current diagnostics

   •  The mitigators present at  the workshop explained the diagnostic

techniques they are currently using.  They ranged from a visual inspection

of the house to a walk through accompanied by some grab samples and

differential pressure measurements and/or subslab and wall communications

testing.  Also discussed, but elaborated on in more detail in the formal

presentations, was  Saum's  diagnostic technique.   His "blower floor"

procedure is tailored to a substructure with sufficient aggregate under

the slab that near  ideal conditions for subslab ventilation exist.  The

diagnostics are designed to assess the size and location of the system


Radon Diagnostic Workshop, 1987.   Phase II Summary

which should be installed, and have proved very useful under these


   •  There was generally agreement by the mitigators that with experience

one can often successfully mitigate a building after only a visual

inspection.   This is perhaps true if subslab ventilation is the mitigation

installed, partially because the success of subslab ventilation is

dependent on at least some communication existing under the slab  (which

does occur in many homes).  A visual inspection by an experienced person

is often enough to decide upon the most expedient location  for the subslab

penetrations and  the exhaust pipe and  fan for  the system.

   •  An installation with no diagnostic measurements, however, cannot

assure  that either too  little or too much air  (with  an accompanying  excess

of basement air)  is being drawn into the  subslab ventilation  system.

Currently, however, many  mitigators are using  no pre-mitigation

diagnostics. They are  installing subslab ventilation systems  and  using

post mitigation radon  concentrations to motivate any necessary system


   •   Subslab ventilation is  the mitigation system  for which  the  most .

diagnostic measurements have been developed and performed,  to date.

   •   The most  important  and  useful test  in this category  is

communications  testing.   A vacuum cleaner  is commonly used to pump on a

given  hole through the  slab and the induced change  in air  flow  (speed but

most importantly  direction) is monitored  through other holes  which have

been drilled through  the  slab and temporarily  sealed.  In  some cases a

Radon Diagnostics Workshop, 1987.   Phase II Summary

variable speed pump is used.  Good communication means that sucking on one

hole with a vacuum cleaner will cause air to flow through each of the

other test holes into the subslab space.  The same test can be done for

within wall and subslab to wall communications.

3.   Researcher current diagnostics

   •  The research community is currently working on quantifying the

degree of communication obtained by a known pumping source (and how much

is necessary to maintain subslab depressurization under a variety of

conditions) by measuring the air speed and direction and pressure

differential through each test hole under a variety of conditions.

   •  Grab samples are used in pre-mitigation diagnostics to determine the

location of radon hotspots.  This can be attempted by collecting grab

samples from various test holes through the slab, in the hollow block

walls (if they exist), and  in any cracks or holes or sumps that exist.

The radon concentrations in these various spots, along with the air

velocity and the cross sectional area through which the air is moving,

will give an estimation of  the radon source strength at each test


   •  Grab samples of soil  gas collected outside the perimeter of  the

house (generally from metal pipes which extend one meter below the  soil

surface) along with a soil permeability measurement at the same location

have been used (mostly by researchers searching for some association

between soil gas radon concentration and soil permeability) to determine

which sides of the house may need more attention in the design of  the


Radon Diagnostics Workshop, 1987.  Phase II Summary

subslab ventilation system, i.e. where the radon entry points may be the

most significant.  Unfortunately this diagnostic procedure has not proven

to. be very useful.

4.  Blower door testing

   •  Blower door tests are used for a variety of purposes in pre-

mitigation diagnostics.  Regular blower door tests, which relate the-

amount of air flow into (or out of) a house which maintains a specific

amount of pressurization (or depressurization),  are used to estimate the

effective leakage area, i.e., the "leakiness" associated with a particular

house.  If the test is applied  to the basement area alone it is possible

to determine the amount of air  flow necessary to maintain a basement

pressurization of between  5 and 10 Pascals.  This  is the amount of

counter-pressure which should be sufficient to prevent convective entry of

radon gas.  If the air flow determined from the blower door  test  is less

that about 350 cfm,  (ideally below 200 cfm), basement pressurization may

be a viable mitigation strategy if subslab ventilation is not suitable.

   •  Another use of  a blower door test  is  to determine what amount of  air

exchange  is needed in the  basement or crawlspace for a Heat  Recovery

Ventilator to effectively  remediate  a radon problem.

   •  A depressurization of  the substructure  to  -10 Pascals  can be used in

the summer to simulate winter conditions,  although there  is  some  question

as to the reality of  this  simulation.   In this  -10 Pascal depressurized

mode, grab samples,  pressure differentials, and  air velocities through  the

test holes can be recorded (as  described above)  and used  to  determine


Radon Diagnostics Workshop, 1987.  Phase II Summary

radon source strengths at specific points in the depressurized mode.

5.  Tracer gas measurements

   •  Tracer gas measurements can be used in pre-mitigation diagnostics to

augment communications testing.  Also, leaks through the exterior of the

substructure can be located using tracer gas techniques (and sealed if a

tighter basement is necessary for success of a basement pressurization

system).  Tracer gases can be used for finding a footer drain.

6.  Grab sample questions

   •  Questions still remain regarding the extent to which grab samples

should be used.  Questions arise because of the diurnal and seasonal

variability in the radon content of the soil and subslab gas and the

dependence of this variability on both environmental and house specific

parameters.  These variations need to be better characterized.

Radon Diagnostics Workshop, 1987.   Phase III Summary



   Four distinct radon mitigation approaches were discussed along with

their related diagnostic procedures.

1.  Sealing

   •  Sealing was the first mitigation method mentioned, where Canadian

studies indicate that a total area equal to one square centimeter opening

in the basement slab or walls is all that can be allowed if the sealing

approach  is  to be successful.  Quality control is extremely important, as

well as the  choice of materials.  Epoxies often don't bond well with

themselves;  they require special surface preparation, and bonding to the

surroundings is vital.

   •  Sealing is viewed as expensive and difficult but not an impossible

task.  The best success would be anticipated in new construction where one

needs, an  experienced team  using common sense in the choice of sealing

methods.  A  specific recommendation was  the use of a sealant such as a

solvent-hardening, rubberized asphalt.

   •  Radon  flux measurements. as a diagnostics tool, point out the

effects of  even pinhole leaks.  Tracer  gas  methods are  also recommended  as

a method  of  assessing radon  leakage paths and whether or not sealing  is


2.   Dilution

   •  Dilution was  the  second general method discussed  for  radon


Radon Diagnostics Workshop, 1987.  Phase III Summary

mitigation.  Cautions with this approach include making certain the

airintake  isn't near radon sources or located close to the ground, and

avoiding short circuiting  (air exiting prior to complete mixing).

   •  The  ultimate desire  is to set up a plug flow situation, i.e., where

an air  flow  sweeps away pollutants rather than mixing them with interior


   •  Diagnostics for dilution methods include the use of the blower door

to evaluate  the  envelope  leakage rate of the house as well as to  catalog

bypass  leakage areas which allow radon to move within the building.  For

example, unless  appropriate  tightness levels are present it may make no

sense to use heat recovery ventilation.  The blower door tests can also be

used to evaluate communication between zones.  Pressure measurements can

be used to make  sure that pressures indoors are slightly positive rather

than negative  to avoid drawing radon into a living area.

   •  Air  flow measurements  may  make use of pitot tubes, heated-wire

anemometers, vane-type anemometers, etc., in ducts or pipes.  A grid-type

measurement, such as a pitot tube  grid, is a superior approach to

averaging  flow profiles.

   •  Tracer gas measurements are  also very useful in flow measurement and

air movements, as well as detecting leaks in the system.

   •  Use  of a continuous radon  monitor as a diagnostic tool  allows

exhaust air  radon concentrations to be evaluated, and to make certain

exhaust flow isn't being  reintroduced to the house by the supply  air.

   •  Because  of shorter  air residence times,  dilution may  result in

reduction  of working levels  greater than the radon  levels themselves.


Radon Diagnostics Workshop, 1987.  Phase III Summary

Radon profiles (multi-location testing) may be used to check for hotspots.

One approach is to flush out the radon with high initial ventilation  and

then observe the ingrowth of radon. This diagnostic method may be used  to

evaluate the amount of ventilation required to meet EPA guidelines.

3. Pressurization

   •  Pressurization  of the basement was the third category discussed.

Separation  of  the basement/crawlspace from the upstairs is an initial

requirement.   If upstairs  air is used to pressurize the basement, care

must be  taken  with the venting of upstairs combustion devices.

   •  Use of the blower door is  recommended to check for air leaks  between

zones, crack leakage  to the outside, and back drafting of appliances.

Flows of approximately 500 cfm,  and pressure differences of at  least  three.

pascals  are provided  as representative numbers for judging airflow

requirements for pressurization.

    •  Turning  on  all  venting appliances and checking whether the  system

maintains proper pressurization  is one way to check performance adequacy

 of the ventilation system.

 4. Subslab  depressurization

    •   Subslab  depressurization was the fourth approach discussed.   Using

 the  slab as the  separation between house space and soil gas

 depressurization  of the  subslab  must be sufficient to overcome  stack

 effects  (buoyant  airflow  in  the  house that depressurizes the basement)  and

venting  appliance  operation  since  the resulting basement depressurization


 Radon Diagnostics Workshop,  1987.   Phase III Summary

can cause soil gas to move through the slab and walls to the living space.

   •  Sensitive pressure measurement techniques (such as electronic

digital manometers) may be used for evaluating the pressure differences

and smoke tracers can determine the direction of air movement.   The lowest

pressure drop locations across the slab are the critical zones  and should

not be located near any radon hotspots.

   •  Since the exhaust from subslab depressurization tends to  contain

high radon concentrations, avoiding re-entrainment is essential; tracer

gas techniques work well in this check.

   •  The exhaust also often contains high levels of moisture,  making it

essential to design piping to avoid water accumulation and eliminate

possible pipe blockage.

   •  Again back drafting of the combustion appliance can be influenced by

the operation of the radon mitigation system since air is being removed

from the house substructure.  Indication of spilling of exhaust products

into the space may be  documented by a small temperature-sensitive  "tab" at

the flue entry.  Spillage tends to be worst at start of combustion

appliance operation.   Use of blower door techniques can also supply

information on the required air leakage necessary to supply combustion

devices.  Dedicated make up air to the appliance is highly desirable.

Radon Diagnostics Workshop, 1987.  Phase IV  Summary


      POST MITIGATION DIAGNOSTICS -  B. Henschel, Chairman

Radon monitoring

    o  Radon monitoring.is the principal post mitigation diagnostic  test commonly

utilized by commercial mitigators.  The first question is --  should the emphasis

be  on  measurement of radon  or  radon proEenv?   Currently  most people measure

radon  gas.   One  reason  is that it  is  simpler  to measure  radon  gas  -- i.e.,

charcoal canisters, and alpha track detectors.  Radon measurements  might provide

a less ambiguous indication of mitigation performance.  Radon might even provide

a better indication of health risk  (given  that  only a relatively inexpensive

measurement can be made,  and that the WL - versus -  particle size measurements

needed  for  dosage/risk models are thus  impractical  for  routine use); the radon

is  tracked by reading the value for Polonium-218, which --  as the  daughter with

the greatest fraction unattached -- probably represents the  largest contribution

to  the health risk.   There  is  a need  for  technical clarification  of the  EPA

guideline   of 4 pCi/L or  0.02.WL  because it  is known that the equilibrium value

relating radon  and radon  progeny varies by  up to  fifty  percent.   From a policy

perspective, however,  the guideline  is sufficient as it is  expressed (4 pCi/L

or  0.02WL)  because no specific  equilibrium  condition is specified or implied.

In  other words,  the  EPA  action  level  is  reached when  concentrations of radon

exceed 4 pCi/L  or radon progeny  exceed 0.02WL.

  2. Who makes  the measurements?

    o   Post mitigation radon monitoring also  involves the  question of who

Radon Diagnostics Workshop, 1987.  Phase IV  Summary

makes the measurement?  A mitigator faced with the question of liability

needs a direct knowledge of how the mitigation system is functioning.

Also, information on the success of the mitigation method aids the

mitigator in selecting mitigation approaches  for other homes.   The

homeowner is concerned that the problem has really been solved and might

want an independent measurement, made by someone other than the mitigator.

Federal or state government representatives may be most interested in how

well the mitigators are performing from a public health standpoint, and

therefore may desire an independent evaluation of radon levels.  These

results may dictate which mitigators are placed on a "recommended list",

where states maintain such a list.

3.  Length of testing

   •  The next question involves the length of testing.  Short-term

monitoring is essential, immediately after radon mitigation system

installation, to confirm that the system is functioning properly.  In

addition to this immediate measurement, an integrated measurement over two

to three months  (alpha track) in the winter (to provide a worst case test

of the system over a reasonable  time period)  is a recommended  minimum


   •  The need to develop  two-week monitors as an intermediate measure was

also discussed.

   •  Arriving at an annual average radon exposure  is  a point  that needs

further clarification; if  the 4  pCi/L  guideline is  interpreted as  the

annual average that a homeowner  should try to achieve, then measurements


Radon Diagnostics Workshop,  1987.   Phase IV Summary

 might cover a full year.

   •  Multi-year monitoring could be valuable in evaluating changes in

mitigation system efficiency and/or variations in the radon source

strength over time.  Annual and multiyear measurements would probably not

be conducted by the mitigator, but would be the responsibility of the

homeowner, or might be carried out by researchers or state agencies.

   •  Inexpensive monitoring devices may be heading to the market place to

help solve some of these radon monitoring problems.

4.  Where do you monitor?

   •  Measurements are normally done in more than one location:  in the

living area, both upstairs and downstairs, in the basement/crawlspace, and

in those locations cited by the homeowner as important.  Protocols must

specify monitoring location.

   •  By surveying the radon levels throughout the house (radon profile),

one is less likely to miss a high radon area, and also these data can be

the basis for estimating total occupant radon exposure.  The basement (or

perhaps crawlspace) area normally registers the highest radon  levels and

thus is most sensitive in revealing if any radon problem still exists

after mitigation.

5.  What monitoring techniques are being  used?

   •  Charcoal  canisters and  alpha track  detectors are popular because of

ease of use and relatively  low cost.  For immediate  radon  level

information, grab  and continuous radon  sampling are  popular.   There remain


Radon Diagnostics Workshop, 1987.  Phase IV  Summary

several uncertainties associated with the interpretation of grab sample

data because of the large variation in indoor radon levels (which is

evident from continuous radon data).

   •  In view of all the uncertainties, there would appear to be a need

for a standardized procedure that could be routinely applied in the post

mitigation period.

6.  Other diagnostics

   •  Diagnostics other than checking radon concentrations are usually not

done routinely by commercial mitigators.

   •  Testing of the final pressure field under the slab after

installation of a subslab ventilation system was emphasized by several of

the workshop participants  as an  important item to consider as a post

mitigation diagnostic measurement.

   •  Assurance that combustion  devices are not back drafting is also an

important post mitigation measurement to make.

   •  Measurement of flows and pressures in the piping associated with the

mitigation system can be important in the post mitigation diagnostics as

well as during system installation.

   •  Mounting a gauge on  the piping to indicate proper system function is

being used and is a form of post mitigation diagnostics that provide

assurance to the homeowner that  the system is functioning satisfactorily.


   The following presentations preceded the actual workshop discussions.

The purpose was to introduce the workshop attendees to the spectrum of

radon diagnostic subject matter presented by researchers and practitioners

who represented the cutting edge of radon diagnostics and mitigation

technology.  These presentations, of necessity, were concise, but the

workshop participants were given adequate time to pose questions to gain

more detailed  information on those areas of particular interest.  Further

references were provided in many instances, and a reference  section has

also been  included  in this workshop summary.

              The worse descrisea in this paper was not funded by the U.S. Environmental
              Protection Agency. The contents do not necessarily reflect the views of the
              Agency and no official endorsement should be inferred.

                            GENERAL CONSIDERATIONS
                          RELATED  TO RADON DIAGNOSTICS
                                J.  Tell  Tappan
                              ARIX  Sciences  Inc.
                           Grand  Junction, CO 81501


     Numerous diagnostic  techniques have been used for determining the
     existence and extent of  a  radon problem.  These techniques are  generally
     categorized in  four  sequential phases;  initial problem assessment,  pre-
     mitigation. mitigation installation, and post-mitigation.  This paper
     presents a general  overview  of the various techniques used during  these
     four basic phases of diagnostics.


     Diagnostic techniques used for this phase can be  applied to  open land
     areas, as well  as existing structures and their sites.  The  normal
     approach includes identifying  areas that are geologically prone to radon,
     and then surveying  specific  sites within the radon-prone area to confirm
     the presence of  a radon  problem.   The sequence of diagnostics related to
     this initial assessment  is discussed below.

     2.1  Geologic Characterization

          A review of individual  state .geologic maps serves as the basis for
          identifying potentially elevated radon areas.  The primary geologic
          formations  that accommodate  elevated radon are as follows:

          •  Granitic Rocks

             Granitic formations  are generally associated with higher
             concentrations of  uranium than  other formations.  The uranium
             enrichment  occurs  naturally due to the geochemical composition.
             Additionally, fractures are routinely associated with granites,
             and the  fractures  accommodate remobilization and concentration of
             uranium  within the fractured areas.

          •  Marine Black Shales

             These formations are primarily  carbonaceous (plant derived
             material) shales,  and  in  many cases low concentrations  or  seams
             of coal  are  related  to the shales.  The carbonaceous  materials
             tend to  absorb uranium during initial deposition.  Additionally,
             uranium  migration  associated with ground water results  in
             enriching the carbonaceous materials, since these materials
             essentially  act  like a sponge relative to the radioactive

     •  Silty Shale Containing Phosphate

        These formations are always naturally enriched with uranium.
        Many  phosphate milling operations actually reclaim the uranium
        (yellow cake)  from the phosphate tailings on a profitable basis.
        It is not uncommon to find uranium concentrations ranging from 50
        to 100 ppm in these formations.

     •  Thorium and Rare-Earth Occurrence

        These occurrences are generally related to several geologic
        characteristics; alkalic rocks, carbonatites, senites, granites.
        and in veins.   The U.S. Geological Survey has two open-file
        reports, 79-576T and 79-576U, that have mapped these occurrences
        within the conterminous United States.

     •  Soil  Permeability

        Review of state geologic maps can assist in characterizing
        permeability of soils that overlay geologic formations of
        concern.  These data are useful in estimating radon emanation to
        the soil surface.

2.2  Gamia-Ray Anomalies

        Gamma-ray anomalies can be related to daughter products  of
        uranium, thorium, and potassium.  In the case of uranium, the
        daughter product bismuth-214 (which is also a radon daughter) can
        contribute to the gamma-ray anomaly.  Identification of  these
        anomalies is generally based on a historical data review and
        field surveys as follows:

     •  Historical Data

        In 197A, the U.S. Department of Energy (DOE) initiated the
        National Uranium Resource Evaluation (NURE) program.  This was
        prompted by the need to address concerns over the available
        uranium supply  for nuclear reactors.  Aerial radiometric surveys
        were  flown, using sensitive gamma-ray spectrometers_that measured
        uranium, thorium, potassium, and bismuth.  All but four  of  the
        quadrangles in  the conterminous 48 states were surveyed; 99 of
        154 quadrangles in Alaska were also flown.  The flight line
        spacing varied  from a quarter mile in detailed surveys to six
        miles in areas  not expected to contain significant uranium
        concentrations.  Maps produced by the DOE depicting the  uranium
        occurrences identified by this survey are useful in defining the
        naturally-occurring concentrations of radon on a regional basis.

        Many states have completed gamma-ray surveys using mobile gamma
        scanning vans or hand-held portable gamma scintillometers.  These
        survey results have been mapped by the appropriate states and
        they are useful in defining near-surface anomalies that will
        produce radon problems.

     •  Field Surveys

        A gamma-ray scintillation detector incorporating a multi-channel
        analyzer has been mounted on a van-type vehicle to accommodate a
        mobile survey within areas of concern.  The detector is normally
        shielded to direct sensitivity to a single side of the mobile
        unit.  A recorder is incorporated with the system, and recorded
        gamma anomalies are related to physical location by hand.
        Accumulated- data are useful in identifying specific structures or
        building sites where there is a high probability of elevated

        Gamma-ray surveys are also performed on foot using hand-held
        scintillometers.  For individual building sites a scanning
        technique, with the detector about two inches above the surface,
        is used and data are recorded on a 10-foot grid basis.  Existing
        structures are also thoroughly scanned and data are recorded on
        an appropriate floor/plot plan sketch.  Anomalies identified are
        useful in identifying specific "hot" spots where elevated radon
        is likely.

2.3  Soil Radon Gas and Flux Rate Measurements

     Soil radon characterizations are particularly useful in diagnosing
     open ground areas planned as building sites.  Two techniques are
     normally used; one that measures the radon concentration contained
     in the near surface soils, and one that measures the radon flux rate
     on the surface area.  These techniques are discussed below.

     •  Soil Gas Radon Concentrations

        Alpha track film detectors are normally used to make these
        measurements.  The detectors are normally placed on the surface
        soil in a grid pattern over the area of interest; areas where
        gamma-ray anomalies have been identified are always included in
        the sampling.  Detectors are also placed over or within soil
        boreholes of varying depths to accommodate soil gas measurements
        from subsurface soil layers.  Data from the alpha track film are
        plotted on an appropriate plot plan map; this mapping shows a
        soil gas profile over the area of interest.  These data are
        useful in determining the soil radon concentration related to a
        specific location planned for building.  To date, a precise
        method for relating these measurements to an indoor radon
        concentration has not be determined.

     •  Radon Flux Measurements

        Two radon flux measurement techniques are commonly used; charcoal
        absorption and accumulator.  Since radon transport or migration
        through soil is highly dependent on soil permeability, moisture
        and several other parameters, flux measurements are normally made
        at the location of a hole  (dug or bored) that represent the
        footing depth of the planned structure.  Measurements are made in
        units of pico-Curies of radon per square meter (pCi/m^).  The
        resulting data is related  to a flux rate of < 2 pCi/m^ which is
        associated with soils where the habitable structures do not
        contain elevated radon concentrations.  Areas measuring in excess
        of 2 pCi/m^ can be expected to produce a radon problem  in an
        enclosed structure.

2.4  Structural and Occupancy Characteristics

     Visual inspection of the structure and general habits of the
     occupants are important factors related to indoor radon problems.
     The structure design and condition of structural components have a
     direct relationship to the problem since these parameters  can either
     produce a radon barrier or an influx route.  Additionally, occupancy
     characteristics have a significant relationship to the air exchange
     rate and indoor pressure differentials associated with the
     structure.  Techniques normally used to diagnose these
     characteristics are discussed below.

     •  Visual Structure Inspection

        This technique includes identification of apparent major radon
        influx routes such as open soil areas, sumps, structural cracks,
        fence drains, porosity of  structural components, and use of
        exhaust fans.  These observations are normally recorded on a
        standardized form, and the data is useful for evaluating
        complexity relative to possible remediation.

     •  Occupancy Characteristics

        This technique includes having the occupants fill out a
        standardized form indicating the number and age of occupants,
        smoking habits, occupants  that work outside the home, and other
        data that can be related to the occupant-induced ventilation of
        the structure.  Additionally, other related data are normally
        obtained during structure  inspections through conversation-with
        the occupant.

2.5  Indoor Radon Profile

     This diagnostic effort includes measurement of radon and radon
     decay-product concentration (RDC) in various zones or regions of a
     habitable structure.  Several measurement techniques are routinely
     used that can generally be categorized in three groups; grab
     sampling, integrated monitoring, and continuous monitoring.

Resulting data are useful in identifying concentration gradients
that indicate regions of significant radon influx or stagnant air.
Additionally, simultaneous radon/RDC measurements will identify the
equilibrium state of the decay product, and the age  (equilibrium
state) of the decay products can be related to the air exchange rate
of the structure.  The techniques used to obtain this profile data
are discussed below.

•  Grab Sampling

   This technique includes collecting simultaneous radon and RDC
   measurements from various locations representing all indoor areas
   of the home.  Equipment includes radon scintillation cells, low
   volume air sample pumps incorporating a glass fiber filler, and
   appropriate photo-multiplier tube detectors with  sealers.

   The number and location of samples required is site specific
   depending on the number of floor levels and configurations of
   room partitioning associated with the home.  The  following sample
   location selection criteria will generally apply:

   •  Basement -  Usually a minimum of two locations, one in either
      end; however, can  require four locations in basic quadrants if
      partitioning indicates isolation of one area from another.

   •  Crawl spaces -  Usually one location near the  center  of the
      crawl space, followed by one location in the living space
      directly above the crawl space location.

   •  Main floor above basement -  Usually a minimum of two
      locations, one in  the main living space and one in the
      opposite end of the house in a closed bedroom.

   •  Third level of two story house -  Usually one  location from
      closed bedroom; an additional sample is required if open
      living area is present.

   In summary, radon profile sample locations required for  each home
   will vary from a minimum of 4 to as many as 9.

   Accumulated data are normally summarized on an appropriate
   "standard" form.  The radon and related RDC is recorded  for each
   sample location, and  the equilibrium state of the RDC is
   calculated for each location.  These data are averaged to show
   the overall house radon and decay product concentrations as well
   as the average equilibrium state.

             With respect to the measured equilibrium. 50-percent equilibrium
             is  equivalent to 38 minute old radon decay products, which
             equates to approximately 1.6 air exchanges per hour.  This
             information is a "rule of thumb", since decay product plate-out
             and other factors are ignored.  However, the data is useful in
             determining structure ventilation prior to and during sampling,
             and it serves as a good indicator of the validity of the sampling

          •  Integrated Monitoring

             Carbon canisters, alpha track film, and the Environmental
             Protection Agency (EPA) Radon Progeny Integrating Sampling Unit
             (RPISU) are commonly used to accommodate this radon profiling
             technique.  The sampling device is placed in a single area of
             interest, or in various regions of the house as discussed in
             relation to grab sampling.

             Normally measurements are made over a 2 to 5 day period, and
             results are interpreted over this sampling period.  These data are
             useful in identifying areas of primary radon influx, as well as
             for confirming the presence of an indoor radon problem.

          •  Continuous Monitoring

             Several manufactures produce continuous monitors for measuring
             radon or radon decay-product concentrations.  These monitors are
             deployed in a specific area of concern or various zones  of the
             indoor area.  Sampling periods should be a minimum of one hour,
             and sampling periods of up to several days can be accommodated.
             Resulting data are useful in providing relatively prompt
             information regarding concentration gradients, and confirmation
             of  a radon problem is easily obtained.


     This phase of diagnostics accommodates collection of data from indoor
     areas, and these data are the basis for identifying appropriate  site
     specific radon mitigation techniques that can be applied to the
     structure.   The basic techniques used can be generalized in three
     categories; radon grab sampling of structural components or zones, radon
     flux rate measurements from structural components or features, and
     pressure measurements and alterations.  These techniques are briefly
     discussed below.

3.1  Radon Grab Sampling

     Flow-through type radon scintillation cells are normally used  to
     accommodate this diagnostic effort.  Samples are collected  from
     inside hollow walls (through a drill hole or from behind an
     electrical switch plate), from water drain sumps, from beneath
     concrete floor slabs (through drilled holes), or any other
     structural component or area of interest.  Resulting data identifies
     areas or components with significant radon concentrations that may
     be suspected as major contributors to the indoor radon problem.

3.2  Radon Flux Measurements

     The charcoal absorption or accumulator methods are normally  used  to
     accommodate these measurements.  The sampling device is sealed over
     the surface area of interest for a timed interval, and resulting
     data is calculated in pCi/m^.  Sample collection locations normally
     include each basement foundation wall, the floor/wall joint, the
     solid floor, and any structural cracks that could accommodate
     significant radon entry.  The accumulated data provides a comparison
     of the radon source significance related to structural components or
     features sampled.  This information aids in determining which
     structural feature should be mitigated to obtain the most
     significant radon reduction.

3.3  Pressure Measurements and Alterations

     These diagnostics normally incorporate use of fans, blower doors,
     pressure and air flow rate measurement devices, and tracer in  gases.
     Pressure differentials are measured in areas of interest and indoor
     zones.  Specific areas or zones in the house are pressurized or
     depressurized through use of' fans, connections through floor slabs
     or into walls, and blower doors as appropriate.  Radon sampling is
     normally performed between each induced pressure change to determine
     the effect on radon concentrations.

     Air movement and velocities are measured through structural  test
     holes to identify communication from one point to another.   Inert
     tracer gases are often injected in areas of interest and resulting
     measurements are also used to determine communication between
     specific points.

     Blower door tests or inert tracer gas injections are normally  used
     to evaluate the building envelop tightness.  These techniques  will
     be discussed in detail by other workshop participants.

          In summary, pressures are  recognized as a  dominating  factor  relative
          to radon influx rates.  Diagnostic techniques  used  are highly
          variable as is the equipment incorporated  with the  techniques.
          Information gathered is useful for determining the  effect  of
          occupant or meteriologically induced pressure  charges.


     Diagnostics used for this phase include measurements and observations to
     assure the quality  and integrity of the installed mitigation system.
     These parameters are discussed  below:

     4.1  System Quality

          The primary quality factors are materials  used,  craftsmanship
          applied, and the cosmetic  effect  the system  has on  the  interior
          area.  Quality products must be used,  and  installation  must  be
          accomplished using industry craftsmanship  standards.   In all cases,
          system installation should be accomplished in  a cosmetically
          acceptable and pleasing manner to the  extent that is  practical.

     4.2  System Integrity

          Diagnostics to assure system integrity includes balancing air  flow
          within the system, tracer  gas injections to  identify  leakage or
          determine  exhaust backdraft, and  pressure  differential  measurements
          in specific areas or zones.

          Simple smoke tube techniques can  usually identify significant  single
          point system leaka-ge or backdrafts, however, other  tracer gases
          injected into  the system will provide  better identification  of
          leakage related to several small  points that are significant when

          Pressure differential measurements from specific areas  and zones
          will identify  system induced changes that  may  affect  the radon
          influx.  It is possible to create a negative pressure with an  active
          mitigation system, and this will  normally  result in increased  radon
          influx.  Conversely, over  pressurization of  a  radon influx zone  will
          either reduce  the influx rate or  force increased radon
          concentrations into other  areas of the structure.


     Diagnostics related to this phase will  identify  the  most  efficient
     operational mode of the mitigation  system,  and evaluate  the  systems
     overall performance relative  to desired indoor radon reduction.   After
     the operational efficiency and overall  effectiveness of  the  system  has
     been determined, various appropriate  diagnostic  measurements discussed
     previously may be required in the event indoor radon concentrations
     remain above the desired level.  These  aspects of  diagnostics are
     discussed below.

     5.1  Effectiveness Evaluation

          The indoor radon profiling techniques,  previously discussed in
          Section 2.5. are normally used to  determine radon/radon decay-
          product concentrations in various  areas or  zones throughout the
          structure after the mitigation system  is activated.   These  data
          provide relatively prompt information  regarding radon reduction
          achieved.  If the mitigation system  incorporates blowers or fans,
          speeds of these units are increased  or decreased to  obtain  maximum
          radon removal and energy efficiency; re-sampling radon  profile
          locations is accomplished after  each adjustment to  accommodate this

     5 .2  Additional Remediation Considerations

          If the post-mitigation effectiveness diagnostics indicate need for
          additional remediation, various  techniques  (discussed previously)
          are used to determine appropriate  options.   Since these techniques
          have been discussed previously,  the  following simply lists
          techniques commonly used in the  order  of personal preferences:

          •  Radon flux rate measurements  to determine  primary structural
             contributors remaining.

          •  Radon grab sampling from structural  areas  sampled during pre-
             mitigation diagnostics and  other  suspect areas to determine
             elevated sources remaining.

          •  Re-measurement of delta pressures,  air flow  rates, and  air
             movement directions to determine  need for  further system

          •  Additional visual examination of  structure characteristics  to
             identify any possible oversights.

     This paper has been reviewed in accordance with the U.S. Environmental
     Protection Agency's peer and administrative review policies and approved for
     presentation and publication.
Use of Vehicle-Mounted Radiological  Equipment
in the Diagnosis  of  Houses  with  Elevated Levels of
Radon and  Its  Short-Lived Progeny

C. S. Dudney,  B.  A.  Berven,
T. G. Matthews, and  A.  R. Hawthorne

Health and Safety Research  Division
Oak Ridge  National Laboratory
Oak Ridge, TN  37831

I. Introduction

Since^he  discovery  of American  homes with levels of indoor
radon   progeny far  in excess  of the levels allowed in
underground mines by governmental regulations, there has
been greatly increased awareness of  radon in residential
environments.  Homes with high levels of indoor radon have
also been  identified in .Scandinavia.  Underground miners
exposed to radon  progeny  have  experienced elevated incidence
of fatal lung  cancers and it is  suspected that residential
exposure may also lead to cases  of lung cancer.  Nero et al.
(1986) have estimated that  1 to  3% of American homes have
annual average levels of  radon in excess'Of 296 Bq/m .  The
federal government (U.S.  EPA and CDC, 1986) has estimated
that lifetime  exposure to levels of  radon above 296 Bg/ro3
will increase  lifetime absolute'risk of fatal lung cancer by
at least 26 chances  in 1000.

Many factors are  important  in  the identification of houses
with elevated  levels of radon.   Since indoor radon comes
predominantly  from the rock and  soil near a house,
geological factors are important.  Occupant behavior,
building structure and weather are important factors because
exchange of indoor and outdoor air is a principal means of
dilution of indoor radon.   This  paper will briefly discuss
the use of vehicle-mounted  equipment in the assessment of

  Research sponsored by the U.S.  Environmental Protection
Agency under Interagency  Agreement No.  40-1709-85, by the
Tennessee  Valley  Authority  under Interagency Agreement No.
40-1459-84, and by the Offices of Health and Environmental
Research and of Remedial  Action  and  Waste Technology of the
U.S. Department of Energy under  Martin Marietta Energy
Systems, Inc., contract No. DE-AC05-840R21400 with the U.S.
Department of  Energy.
  References to radon in  this  paper  refer to 222Rn unless
otherwise  noted.

 some  of  these  factors,  principally building and geological
 ones,  in studies  that  either  seek to  identify houses of
 concern  or  to  identify radon  entry points and sources  in
 selected houses.   Emphasis will be given to work that  has
 been  performed by Oak  Ridge National  Laboratory  (ORKL) staff
 during the  last ten  years.

 II. Description of Vehicles

 Two principal  types  of vehicles have  been used by ORKL staff
 in their radiological  surveys.  The radiological scanning
 vehicles have  been used to investigate spatially dependent
 anomalies in the  gamr.a radiation field at selected
 locations.  The mobile radiological laboratory has been used
 to provide  logistical  support to surveys requiring
 radiological measurer.ents at  sites that may lack electrical
 power or other requirements.

 A. Scanning Van

 A mobile garnr^a scanning system has been developed for  the
 U.S.  Department of Energy  (DOE) by ORNL staff.  The unit was
 originally  developed in 1979  and its  performance was
 enhanced following a research and development project  in
 1981.  The  vehicle provides continuous nuclide-specific
 analyses while in motion.

 The detection  system consists of a Nal(Tl) crystal, shielded
 so that  photons principally originating from the passenger
 side  of  the vehicle  are detected.  The system is controlled
 by the operator through an on-board computer, with data
 output provided to the  computer monitor, strip chart
 recorders,  and a  printer.  Data are also stored onto floppy
 disks.   Multichannel analysis capabilities are provided for
 qualitative radionuclide identifications.  A 22°Ra-specific
 algorithm is currently  employed to identify locations
 containing  residual  radium-bearing materials.

 The primary mission  of  the mobile scanning van is to locate
 and identify those building lots on which there is evidence
 of residual radioactive material above local background
 levels.   Typically,  the scanning surveys are conducted as
 the final stage of the  identification process and are used
 to (1) document locations that were identified from
 historical  records,  (2) provide ground-level surveying in
 support  of  aerial  survey efforts, and (3) screen large areas
•of a  residential  neighborhood on a street-by-street basis.
 In identifying  lots where contaminated materials exist, the
 scanning  system is used to detect changes in the gamma
 radiation field associated with the site, as observed from
 accessible  roadways or  other public thoroughfares.

B. Mobile Radiological Laboratory

The staff at ORNL have also developed two mobile
radiological laboratories.  During surveys, a mobile
laboratory can serve as a control center as well as housing
instruments and other needed equipment.  Each vehicle is a
modified motor home equipped with its own electric
generator, desktop computer, and radiological instruments.
The radiological capabilities pertinent to radon diagnosis
that can be performed on site include analysis of short-term
samples for airborne radon and airborne progeny from 222Rn,
2  Rn, and 2^Rn.  A detailed description of these
techniques is given below.  In addition, crude radiological
analyses of soil can be performed using Nal(Tl)  well

III. Identification of Houses for Further Study

Because only a small fraction of U.S. houses are currently
thought to require remediation for radon progeny exposures,
it will be necessary to identify those residences needing
further evaluation.  In cases where the radon precursors are
inhomogeneously distributed in the soil, it has been
possible to investigate the gamma radiation field near
houses while avoiding intrusions onto private property by
using the mobile scanning van.  These kinds of studies have
allowed investigators to target residences for more detailed
assessments.  In cases where radon precursors are more
homogeneously distributed, the only methods identified so
far for identification of potential problem areas have
involved geological assessment or untargeted measurements
within houses and will not be discussed here.

A. Uranium Kill Tailings

Currently there is a large ORNL field office near Grand
Junction, Colorado, out of which health physicists,
geologists, and other ORNL staff are assisting in the
identification of houses and building lots that are eligible
for remediation under the Uranium Mill Tailings Remedial
Action Project.  Federal law, as implemented by 40CFR192,
stipulates that DOE will offer to remediate buildings or
homes at which there is evidence of mill tailings from the
government's uranium mining programs in the 1940's and
1950's.  Properties can qualify in various ways for this
program, one of which is demonstrating both annual average
radon progeny levels in excess of 0.02 WL  and the presence
of uranium mill tailings.  This program provides for the
 One working level (WL)  means any combination of short-lived
radon progeny in one liter of air that will  result in the
ultimate emission of 1.3 x 105 MeV of potential  alpha

removal and replacement of soil around qualifying buildings
and residences.

To facilitate the completion of this program, radiological
scanning vehicles have been used to identify potential
candidate houses without intruding on building occupants.
By slowly driving the scan van, described in Section II.A,
down public roads it is possible to flag sites of
radiological anomalies.  In this case, the anomalies for
which a search  is made are those related to emissions from
226Ra or 232Th  progeny.

B. Radioactive  Waste from Dump Sites

There is a similar need for remediation in areas where soil
from radiologically contaminated landfills has been used for
backfill around homes.  For example, in West Orange, New
Jersey, waste from a radium dial painting facility was
disposed of at  several landfills in the 1930's and 1.940's.
Subsequently, houses were built above some of these
landfills and there is now an effort to remove the radium-
containing soil from near the adversely affected houses.
When there is reason to suspect that some homes in a region
may have a problem but it is not possible to identify them
explicitly from historical records, then the use of a scan
van or similar  vehicle may be warranted.

IV. Identification of Sources Within the House

After a house has been identified as having a radon problem,
there are potential uses for vehicle-mounted equipment in
the identification of points of entry-  The techniques
historically used at ORNL will be discussed here.  With the
recent advent of more compact, light-weight electronic
equipment, alternative methods are available to make some of
these assessments.

A. Radon

Air samples collected near a single point in space and over
a relatively short interval of time (i.e.,  less than 5 min),
can be used to  estimate the spatial distribution of radon
levels within a residence.   In this way, entry points with
significant elevation of radon gas may be located.

A modified Lucas cell is used to measure radon (Volchok and
dePlanque, 1985).  The cell consists of a 500-mL plastic
flask with interior surfaces coated with zinc sulfide.  Room
air is transferred into the flask and it is held for at
least 4 h to let all preexisting radon progeny decay.  The
flask is then placed in a counting well on the vehicle and
total alpha activity determined with a photomultiplier and a
single channel analyzer.   Currently, there are commercially

available, battery-powered, portable systems that perform
the same function.

B. Radon and Thoron Progeny

Another indicator of radon (or thoron,' 220Rn)  entry points
is measurement of progeny levels to estimate the spatial
distribution.  Due to the short half-lives of these species,
more complex techniques are employed to measure levels of
specific airborne progeny.

To collect a sample of airborne radon or thoron progeny,
room air is pumped through a filter with pore size less than
one micron.  Most progeny, both attached and unattached to
particulate matter, will be trapped on the filter and can be
analyzed for alpha activity.  The protocol used at ORNL has
called for drawing 100-200 L through a 0.45 urn filter in ten
min.  The filter is then taken to the mobile radiological
laboratory and mounted below a surface barrier detector with
helium gas flowing over the surface of the exposed filter.
The heliur. serves to reduce the energy dispersion of
observed disintegrations of any given alpha energy.  Between
2 and 12 min and between 15 and 30 min after the cessation
of pumping, energy-resolved data from the detector are
acquired into a 512-channel analyzer.  Using the algorithms
of Perdue et al. (1980), concentrations of progeny from
222Rn, 22 Rn, and 219Rn can be estimated.

C. Working Level Ratio

Another indicator of radon entry points that may be used in
the future is the ratio of progeny levels to radon levels.
As radon-containing air ages, the progeny to radon ratio
increases.  Using the techniques described above or
equivalent ones, it is possible to measure radon and its
progeny at nearly simultaneous times at several locations.
Figure 1 summarizes data from a survey of 70 houses in four
states and shows that on average, air in basements has a 36%
lower ratio of progeny to radon compared to air sampled on
the floor above the basement.

V. Identification of Sources Away from the House

The scanning van has been used to investigate the relative
abundance of 226Ra in various geological strata near some
houses with elevated radon levels.   In Huntsville,  Ala.,
four of eight houses studied had radon levels between 740
and 2220 Bq/m  (Dudney et al., 1987).  A team of geologists
investigated the geological strata in Madison County to
determine which strata contained significant levels of
226Ra.  Of eight strata measured, the radium content of
Chattanooga Shale was 20-fold higher than that of any other
stratum.  There is a layer of bedrock above the shale and
below the studied houses that is approximately 500 feet


thick.  If we assume that Chattanooga Shale is the source of
most of the radon found in the studied houses, then it has
migrated a substantial distance to reach these houses.

VI. Summary

Vehicle-mounted radiological equipment can be used in a
variety of ways to identify and diagnose houses with radon
problems.  Some of the capabilities can be duplicated using
modern portable electronic devices, but not all.  In some
cases the presence of a vehicle is needed due to the weight
of shielding required or the presence of generators,
computers, and other equipment for more sophisticated

VII. References

Nero, A. V., Schwehr,, M. B., Nazaroff, W. W., and Revzan,
K. L., "Distribution of Airborne Radon-222 Concentrations in
U.S. Homes," Science 234:992-997, 1986.

U.S. Environmental Protection Agency (EPA) and Center for
Disease Control (CDC) of the U.S. Department of Health and
Human Services, 1986, "A Citizen's Guide to Radon," Report
#OPA-86-004, 1986, available from the National Technical
Information Service, Springfield, Va. (USA).

Volchok, H. L., and dePlanque, G., "The EML Procedures
Manual," p. G-25-01 in Report HASL-300, 1985, available from
the National Technical Information Service, Springfield, Va.

Perdue, P. T., Leggett, R. W., and Haywood, F. F.,  "A
Technique for Evaluating Airborne Concentrations of
Daughters of Radon Isotopes," pp. 347-356 in Proceedings of
Third International Symposium on the Natural Radiation
Environment (Eds.  T. F. Gesell and W. M.  Lowder), 1980,
available from the Technical Information Center of  the U.S.
Department of Energy, Oak Ridge, Tn. (USA).

Dudney, C. S., Hawthorne, A. R., Wallace,  R.  G., and Reed,
R. P., "Levels of Radon and Its Short-Lived Progeny in
Alabama Houses," 1987,  Submitted to Health Physics.

                    Upstairs equilibrium ratios tend
                  to be 55% greater than downstairs.
    Upstairs Ratio (%
                                              o o
       20     25     30     35     40     45
Downstairs Working Level Ratio (%)

           Soil Characterization for Radon Availability and Transport

                                    C. Kunz

                 Wadsworth Center for Laboratories  and Research

                             N.Y.S.  Dept.  of Health

                                Albany,  NY 12201

              Report for Radon Diagnostics Workshop Princeton University

                                13-14 April 1987


     To  identify high risk areas and to gain a better  understanding  of  the

causes for above average  levels  of  indoor  radon it  is  necessary to characterize

the surficial  soils and bedrock  for radon  availability and transport.   Some of

the measurements and measuring  techniques we have used to determine  the

availability and transport of radon in surficial soils and bedrock will be

briefly  discussed  in this report.

     The availability of  radon  refers to  the rate of  formation of radon in the

gaseous  state  (soil gas)  that is available  for transport into homes.  The

availability is related to the  soil and bedrock radium concentration, the

emanating fraction, soil  porosity and soil  gas radon  concentration.  The

transport of radon  is related to the permeability (inverse of resistance) of

the soils and  bedrock for gas flow.

     There is  existing information  available regarding the radium concentration

and permeability of the surficial soils and bedrock.   Most of the U.S.  has been

mapped for surficial Y through  the National Airbourne  Radiometric

Reconnaissance study conducted by the DOE  as part of  the National Uranium

Resource Evaluation program.  These airbourne Nal measurements observe  Y

radiation from about the  first  foot of surficial soil  or rock.  Latitudinal and

longitudinal flight lines were  spaced 3-6 miles and 12-18 miles respectively.

These data should be useful in identifying  regions high in  surficial  radium.

Information from mining and drilling operations  is  also  useful  in  locating

areas high in bedrock uranium and radium.

     For most of the United States there  is  a  great deal of  information

available with regard to soil type, depth, water permeability,  particle size

and bedrock.  Most of the soil information can be obtained from soil

conservation  service data.  Maps of the  surficial  bedrock geology are  also

available in addition to soil, ground water  and  bedrock  data  from  sources such

as drilling logs.  As the understanding of the relationship  of  soil gas

permeability and indoor radon improves the available  surficial  soil and bedrock

information will be of great value in identifying potentially high risk areas.

Surficial Gamma

     Surficial gamma measurements were made  using Nal survey  meters by  placing

the meters directly on the ground.  In addition  to  measuring  the T  flux from

radionuclides in the ground the meters were  sensitive to cosmic rays.   Long

Island soils with geometric means for U-238, Th-232,  Ra-226  and K-40  of 0.9,

0.8, 0.6 and 6.9 respectively averaged 9 yR/hr at the surface.   Of this about 3V

R/hr can be attributed to cosmic rays.  Shallow  soils over black shade  in

Onondoga County with geometric means for U-238,  Th-232,  Ra-226  and K-40 of 2.7,

1.1, 2.3 and 26.7 respectively averaged 14 yR/hr  at  the  surface.   We  have found

that surficial gamma measurements are easily made and are a good indicator of

surficial soil and bedrock with above average  concentrations  of Ra-226. It is

possible that high surficial gamma readings  are  due  to above  average

concentration of U-238, and/or Th-232, and/or K-40 in  soils or rocks with normal

concentrations of Ra—226, however, in general  this  is not  the  case.

Soil Ra-226

     Soil samples of about 1 kgm were usually  collected  from  depths between 2

to 4ft. Occasionally soil profiles were measured by  taking samples at every


foot down  to 4 feet.  The  samples were  sealed in plastic bags and returned to

the laboratory for  analysis.  The soils were dried at 100°C, the moisture

content determined,  and  then passed through a 20 mesh sieve (.841 mm opening).

The gamma  spectrum  of the  fraction passing through the sieve was measured using

either Ge(Li) or Nal     detectors.  Rock samples were broken and passed

through the same 20 mesh sieve.  Samples of about 70 gm were sealed in plastic

bottles for GeLi counting  and about 300 gm were sealed in Al cans for Nal

counting.  A radon-radon daughter in growth period of 3 weeks in the sealed

container  was allowed before counting.  In addition to Ra-226, the

concentration of U-238, Th-232 and K-40 were routinely measured.

     Portable Y spectroscopy equipment  is available and would be very useful

for field  measurements  of  Ra-226.

Soil Gas Rn-222

     The concentration  of  radon in soil gas was measured  using both grab

sampling and time integrating techniques.  Grab samples were taken by driving a

1/2* diameter pipe  into the soil at depths ranging from 1 to 4 ft. (Figure 1).

The end of the pipe was fitted with a driving point and perforated with about

50 small holes (3/32" diameter).  The pipe was attached to a diaphram pump .and

air withdrawn at 200 cc/min for 5 min to purge the pipe and lines.  A 1-liter

evacuated  flask was then filled with soil gas and returned to the laboratory

for Rn-222 measurement using Lucas scintillation cells.  Samples were also

measured in the field by flushing scintillation cells with soil gas and

counting with portable photomultiplier equipment.  Samples were generally taken

at depths  of 2 and 4 ft.   The average Rn concentration in soil gas at 4' was about

a factor of 2 greater than observed for samples taken at 2'.

     Soil gas radon measurements were also made using alpha track detectors

(Figure 2).  Time integrated measurements were made for periods ranging from a


few weeks to several months.  A 6  in. hole was  augered or  dug  to  depths  ranging

from 2 to 4 ft.  A three-inch diameter PVC pipe with  a reducing fitting  on  one

end was placed in the hole and the  soil  tamped  into the  space  around  the  pipe.

A 1 1/2-in. diameter PVC pipe with  a  track etch detector attached to  the  end  is

then placed inside the 3 in pipe and  threading  into the  reducing  fitting.   The

3 in pipe is left in the ground and the  alpha track detector periodically

changed by withdrawing the inside  pipe.  Alpha  track  detectors with membranes

to exclude thoron are used for soil gas  measurements  of  Rn-222.


     The permeability of the soils  for gas flow is measured with  the  apparatus

used to take grab samples of soil  gas (Figure 1).  Soil  gas is withdrawn using

the 1/2 in diameter soil pipe at a  measured  rate  of 200  cc/min.   The  pressure

differential, P (atmospheric) - P  (line), required to maintain the flow  is  also

measured using either a pressure differential transducer or magnehelic pressure

gauges.  The gas flow permeability  is then calculated using a  relationship

reported in "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"  by DSMA AtconLtd., January 1983.

                                 k = 2.5 x 10~?  |

where   Q = 1/min

        P '= cm of water

        K = cm*

     Permeability measurements were generally made at depths of 2' and A'.

Water, bedrock or changes in soil type often  caused the permeability  to change

considerably with depth.

Sample Collection

     In our study samples of soil  and soil gas  and permeability measurements


were generally  taken  at  depths of 2 and A ft., and at  distances  of  about 1 1/2

ft. and > 20  ft.  from the basement wall (Figure 3).   To more  adequately

characterize  the  soil as it relates to radon  entry  into homes; measurements

should be made  to depths of 6 ft. when possible.  For homes with basements,a

soil depth  of 6  ft. would normally be about 1 ft. below the basement  floor.

Profiles with sampling at depths of 2, 4, and 6 ft. would more  adequately

characterize  the  soil volume that contributes most  to the soil  gas radon

entering homes.   Samples taken from beneath the basement floor  from sumps,

floor drains, wall interiors, etc. relate directly  to measurements made in the

soil around the  house.

Tracer Studies

     A passive  perfluorocarbon tracer technique developed at  Brookhaven

National Laboratory was  used to make in house multizone air  infiltration

analyses.   Perfluorocarbon tracers were also  placed in  the  soil near homes and

the fraction  of  emitted  gas that entered the  house  was measured.  The tracer

sources were  placed  in the FVC soil pipes in  the same position  as  the alpha-

track detectors  (Figure  2).  Tracer gas sources were  placed  in  the PVC soil

pipes located 1  1/2  ft.  from the foundation at depths ranging from 2 to 4 ft.

Tests conducted  at 45 homes showed that, on average,  55% of  the emitted tracer

actually entered  the  houses.  Five different  tracer gases are available and

could be placed  at various locations in the soil around or  under a home to

study the flow of soil gas into homes.  These measurements  can  be  integrated

over time period  ranging from about 6 hrs to  several  months.
          The work described in this paper was not funded by the U.S. Environmental
          Protection Agency. The contents do not necessarily reflect the views of the
          Agency and no official endorsement should be inferred.


                                                 Evacuated  Flask
                                                 for  Sampling  Soil  Gas
                                                   Figure 1  Soil probe schematic

    2-4 ft
                                    |3" DIA PVC PIPEi;i
                                     11/2" DIA PVC PIPE
                                    IPLUG          •
                                  • ALPHA TRACK
                              ilill DETECTOR
          Figure 2 Detector placement in the soil


^ 1


r /

r7 r
/ /
/ /
/ /7
t /
/ s
Figure 3   Locations of soil permeability measurements

       The work described in this paper was not funded by the U.S. Environmental
       Protection Agency. The contents do not necessarily reflect the views of the
       Agency and no official endorsement should be inferred.

                        Terry  Brennan
                        ED *4  Box 62
                     Rome, New  York  13440
     Over  the  past   several   years  a  growing  number  of
researchers  and   contractors   have   been  lowering elevated
radon levels in residences  by  a number of techniques. All of
them fit into one  of  the  following categories:

     1 ) Prevent radon entry

          • preventing radon entry by soil depressurization
          or pressurization

          • preventing radon entry by basement

          • preventing radon entry by sealing of entries

     2) Dilution of radon by introducing outside air
        (It is important  that  this does not increase soil
        entry by putting  negative  pressure on the basement)

          • heat recovery balanced flow

          • non-heat  recovery  flow (Blowing in or powered by
            negative  pressure  on the basement)

     There  are  perhaps  a dozen  specific methods that have
been tried with varying degrees of success in lowering radon
concentrations   and    no  doubt    several  more  that  are
experimental,  untried or  undreamed  of.  The advantage to
having  a  number  of techniques available to choose from is
that  it  gives flexibility -  an opportunity to use a method
that has a greater chance of success.
     The  problem  of  course is to  select the one or two from
amoung  the  multitude that   gives  you  greater  chance of
success or Is most appropriate for the situation.
     Here   are    my   thoughts  on  selecting  a  mitigation
technique,  based  on experience,  feelings, the work of many
others  and  of   course  analysis   of  the physics involved.
Please  keep  them  in perspective.  In  many ways they are
Incomplete  or  tentative.  They  are  certainly open to new
thought and modification. I would  be very distressed If they
interfered  with new  insight or discouraged asking questions
by appearing to provide answers when they are really ideas.

Begin at  the House

     Probably  80* of the Information I use to decide on a

mitigation  technique is gathered by using ray eyes and brain
while visiting the house. First thing I do is see what state
of   mind   the   homeowner  is in. I   may   be   the  first
semi-knowledgeable  person  to come in contact with them and
they  may  have  a  number of  fears concerning their health,
their families health (will this affect my  daughter's ability
to  have  children  ?)  and  the  impact on the value of the
property.  I want to keep them from undue panic but not calm
them  down so much that they don't do something about a real
     The second thing I do is get a feeling for the house by
walking around it keeping my mind clear and paying attention
to  ray peripheral vision. I'm  looking for how the building's
put  together,  are there any  unaccounted for volumes in the
house, exhaust fans, furnaces, ways to get pipes around. But
most  importantly  I'm looking for ways that radon can enter
the  building,  how does the building hit the ground, sumps,
footer  drains,  crawlspaces, any place there is a large soil
surface that has good airflow  connection to the house.
     I  am  always asking "What is going on here ?" Where is
radon coming in ? Why is it coming in at all ?

     Then  I  make  a  floorplan and fill out the site form.
This is nothing more than a way to get the information  most
critical  to  selection of a mitigation plan together in one
spot.  The  homeowner  may know if there are exterior footer
drains,  perhaps there are gutters emptying into risers from
the  footer  drains  and you can see them. The homeowner may
have  photographs  of  the  building under construction from
which  you can learn a great deal. Once again it is physical
inspection that tells you most.

Look and see  !!

     The key things  I look for when simply observing are:

For  soil depressurization

     • soil gas entry points using eyes and smoke sticks
     •  anything  that   is   like  a  cavity that has a large
contact with  soil surface
           • hollow core block  walls, cored and reinforced ?
           •  interior or exterior footer drains
           • sump holes (drains or not?)

For  basement  pressurization

     • basement that seems tight and Is easily isolated from
       the upstairs
     • no  combustion appliances upstairs
     • basement that is hard to apply soil depressurization
       to  (finished, hard to seal wall or slab openings)

For dilution with outside air

     • crawlspace or basement that is easy to isolate
       (no freeze problems, few penetrations)
     • tight house
     • lack of other options
Soil Depressurization Tests

     Drill  at  least  two  holes through the slab (basement
floor,  slab  on grade or crawlspace floor). One of these is
1-1/4"  diameter  (coincidentally the O.D. of the hose for a
Eureka Mighty Mite vacuum cleaner), the other 3/8".
     Use  smoke  sticks  to see if soil gas is entering from
the holes (if it is then the make up air must be coming from
somewhere, eh?
     Look  in  the  large  hole. What do you see ? *2 stone,
sand  and  gravel, silt, clay, bedrock ? A good bed of stone
everywhere  and  you  can  easily  depressurize  the  entire
sub-slab  soil  surface (maybe 1800 square feet or so in one
fell suction point).If it is clay it will be hard to get any
pressure  field  to  develop under the slab. If the soil has
settled  away  from the'slab (most likely near the .edge ) you
may  have  good  access  to a large soil surface even if the
sub-slab soil is clay.
     If  the  basement wall is concrete block drill at least
one  3/8"  hole in it. If there is a wall that has a slab on
grade  next  to  it  (like a garage floor, a patio or living
area  as  in a split level design) then drill a 3*8" hole in
that and one hole in another wall.

     Take  a  grab sample under the slab and in holes in the
block  walls  (or  better yet do a sniff with a scintilation
flask).  Are  they  higher  than the basement air ? Are they
higher because it is a major source or because the air under
the slab is very stagnant ? This is one of the tests I'm not
sure how to interpret. Does it really make a difference if I
depressurize  the  soil  in  the  location  with the highest
concentration ? I are sort of using that as a guideline right
now,  but  I  wish someone would do some research to help me
understand grab sample results better.
     Use  the  vacuum  cleaner to put a suction on the large
hole  in  the  slab and check with smoke sticks at the other
holes  that  you've drilled through the slab and walls or at
floor cracks, sump holes and other openings through the slab
that  were  already  present to see how easily air will move
beneath the slab. If there is *2 stone or a cavity under the
slab  this  will  probably be quite far. If it is sand under
the  slab  you can expect a pressure field to develop only 5

to  15 feet away from the suction point.  Sometimes in a very
fine,  tightly  packed soil (fine sand or silt) you will get
no  airflow  with  this  test, but if you release some Freon
under  the  slab at one of the smaller holes it will quickly
move  to  the  vacuum where it can be detected in the vacuum
exhaust  with  a  halogen  detector  of  the  type  used  by
refrigeration  and  air  conditioning  technicians. With the
vacuum  cleaner  not  running you can inject Freon under the
slab  and  find  locations  where  it  leaks  back  into the
basement,   identifying   soil  gas  entry  routes,  and  if
exterior  footer  drains  are present you can sometimes find
where they drain away to daylight by sniffing around outside
and finding Freon exiting to the open air.
     The  purpose  of these tests are to decide whether soil
depressurization can be effectively employed as a mitigation
technique.  If it is easy to develop a pressure field in the
sub-slab  agregate  or  block  wall  then  this  will  be  a
preferred method. If the vacuum cleaner test results show no
airflow but Freon will move or if the vacuum cleaner suction
test  ios marginal (spotty or only a few feet) then sub-slab
suction  might  be  possible  but  should be considered with
other possibilities.

Basement Pressurization

     A  fan  door  test between the basement and upstairs is
done  with  particular  attention  paid to the 10 Pascals or
less  delta  P  range. The test should be run so that air is
being  blown  from  the  upstairs  into the basement. In the
basement another person is checking with smoke sticks to see
when  soil  gas stops entering the building, reverses and is
actually  leaving the basement and being blown back out into
the  soil creating a sort of air pressure shield that forces
soil  gas  away from and around the building. If this can be
accomplished  using  a  small  enough airflow (I'd say less
than  300 cfm at 10 Pascals) then basement pressuriztion may
be considered as a mitigation tehcnique. In this method air
would be drawn from the upstairs house putting some negative
pressure  on  the  upper part of the building and blown into
the  basement  to  pressurize it and prevent soil gas entry.
The   fan  door  test  will  give  you  some  idea  of  what
performance  characteristics a fan would need to do the job.
If  the  airflow rate can be lowered from 300 cfm to 200 cfm
by  sealing  the floor between the basement and the upstairs
then  this  should  not  greatly add to the energy  load from
Infiltration  because  it is just reversing the normal stack
effect  airflow  found  in cool climates In the winter time.
Another precondition for this mehtod would be the absence of
*  fireplace, woodstove or other vented combustion device in
the  upstairs  where  the  pressurization air would be drawn

Dilution of Radon Test

     A  fan  door  test is  done  on  the  whole house to get an
idea of how tight the building  is.  This will aid  in deciding
if introducing dilution air is  a possibilty  for  controlling
radon levels. Armed with some simple  infiltration models and
assuming  that dilution air  can be  added without putting a
negative  pressure on the house  that  would  increase soil gas
entry  an estimate can be made  of the expected reductions in
radon  concentrations  for   varying increases in ventilation
     If there is a crawlspace or basement that would be easy
to isolate from Hvingspace and does  not contain things that
would  need  freeze protection  (or  are  easily protected from
freezing)  then  I would consider isolation  of the space and
passive  ventilation  (followed  by  active  ventilation  if
passive didn't quite do it).

Selecting Th» Mitigation Technique

     When  it  comes  to  selecting a mitigation  method I am
currently using the following order of  preference.

               • soil depressurization  (or  pressurization)
               • basement pressurization
               • isolate and ventilate  (crawlspace or
                 basement )
               • ventilate house

     For  deciding  on  what  do do  within each  of these
categories I am using logic shown in  the decision  charts for
each of these categories at the  end of  this  paper.
     All  of  this  is just used as guidelines and the final
selection   will   involve   aesthetics,   noise,  homeowner
preference,  budget, insight from the mitigation  contractor,
permanence of installation, power consumption, longevity and
a  variety of other more or less subjective  factors that may
overide        the        logic        outlined        above.

      A series of figures  that  summarize this  discussion,
including flow diagram  and summary sheets, are  supplied
on  the pages that follow.

Selecting Mitigation Method
Inuestigate Building by
looking, filling out site forms,
doing qualitatiue and quantitatiue
Use Results of Tests and
Floujcharts to make a List
of Mitigation Techniques to
be Considered
Make the Final Selection Based
on Vour Current Method Prioritization
List and all Those Important Factors
That Flowcharts Don't Rccomodate
flesthetics, Noise, Homeowner
Preference, Contractor Input,
Combinations of House Features
That the Charts Don't flllouj.




mp French
IB Drains


Without Seal |
Footer Bottom |
Drains end Drain*
To Trap i

jSeal to
; Shalloiu
5 iiiith


h. n i ft ( r
* uirt {C
Space DK
To Freeze
$ Isolate ji
^ s
^ Uenlilate 5
Sub Slab Tests

r pauer)
Space Not
To freeze
| EHchan
[Floor and

                           Uacuum Suction






 Sub Slab
          \V ^v^^x^x^'vv\^,'\^^^^.x
           hSub Slab
 Indicated ^Considered
Find EMterior
Footer Drain
Find Large
                                  JL. ^_A
                                      I I

                               $ Seal
Sub Slab

                                             Poured Concrete
                                             Or Stone
    Sealed or
   Greb  Samples
| Block UJall   |
| Suction     |
| Considered  £
I Block LUall   |
I Suction Not  |
I Considered  ^

       Current Prioritization List

  My current order of preference for mitigation
techniques is as follows :

  • Depressurize soil or isolate and uent non-Iiuing
    spaces (use flowcharts for malls and Floors
    to find Luhich methods should be considered
    for the house)

  • Pressurize basement (Do a fan pressurization
    test on the basement using the basement door
    to decide if this is appropriate and if so what
    fan flow at what pressure drop is needed.
    Currently, I'm using 300 cfm as the decision point)
  • fidd uentilation air to dilute the radon (Use a fan,
    test on the whole house to help decide if adding
    dilution air mill prouide the reductions needed
    assuming that it can be done with balanced
    or positiue pressure flow).

                          HOUSE  SUMMARY  SHEET

                      HOUSE SUMMARY SHEET - PAGE 2
Exhaust Devices

	  Bath Fans
	  Range Fans
	  Kitchen Fans
	  Whole House Fan
Heating System Type
Thermal Bypasses
	  Around Chimney
	  Balloon Walls
	  Attic Scuttle
Other Bypasses  	
        Plunbing  Chase
        Recessed  Lights
        Bath  Fans
        Pocket  Doors
Time Integrated
Date                     Location

                         HOUSE  SUMMARY  SHEET  -  PAGE  3
   Grab Samples
   Date                     Location             Results            Units
Suggested Mitigation Strategies:


         This paper has been reviewed in accordance with the U.S. Environmental
         Protection Agency's peer and administrative review policies and approved for
         presentation and publication.

                             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

(Editor's  Note:  The following pages are an abstract  of the report,  EPA-
600/8-88-084 (NTIS PB88-225115),  June  1988, not available at the time
of the Workshop.)

    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
Riclge  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,
th; fc!!cv,-;r.- 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

    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
                             TABLE I:  Project Measurement Activities
           I)  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 wir.dspeed and direction,

              •   pressure differentials across ths 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,

              •  iracer gas (SF.) injection in soil and resulting concentrations within the
                 building shell (if utilized), and

              •  additional parameters specific to the mitigation technique under investigation,
                 such as the.flc.*' rate of air through a block wall or subslab ventilation system,
                 or tracer gas analysis of flow pathways.


    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 a/., (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 most 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.

                                     TABLE 2:   Instruments and Equipment
Radon Grab Sampling:
                                   Alpha scintillation calls
                                   Portable photomultiplier tube counting station
                                   Band pump with sample tube and 0.8 iaa filter
                                   Compresaed air or nitrogen for cell flushing
                                   Vacuum pump for evacuating cells (70 cm, 27 in. Hg vacuum)
Air Leakage and Flow
                                   Calibrated-flow blower door  (6800 m3h"1, 4000  cfm 9  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 m h  ,
                                   1.5 m  (5 ft.) flow sections of  :

                                   Non-toxic tracer gas  (SF
                                                                          100 cfm 8 2m,  80  in. H_0 pressure)
                                                                     7.5 em  (3  in.) PVC with  coupler
                                                                     15 cm (6 in.) galvanized duct
                                                              Freon 12)
                                   Tracer gas detection instrument
Soils Characterization:
                                   Soil core and auger samplers
                                   3/4" reversible electric drill
                                   Soil air permeability device
                                   Sliding hammers
                                   Various diameter drill bits, including some
                                        attached 1.5 m (5 ft.) long extensions
                                   1.5m (5 ft.) long probe pipes
Inspection Equipment:
                                    Stiff wires
                                    Telescoping mirrors
                                    Portable  gama  spectrometer
                                    Fiber optics  scope
                                    3/8"  variable  speed hand  drill
                                    Masonry bits
                                    1/2"  hammer drill
                                    Impact bit*
                                    Pocket flashlights
                                    Band  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 leal
                                   0.3. 0.8. 1 cm  (1/8, 1/4,  3/8  in.) diameter tubing
                                   Various-sized hypodermic  needles
                                   Plastic  film
                                   Thermometers:   electronic and  mercury-filled  glass
                                   Silicons sealant


    A "General Plan  for  Radon Control",  shown in Figure I, 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 (i.e., 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  report    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  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.

           This work is cofunded by the U.S. Department of Energy (DOE) and by the US
           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. Ofice of Energy Research",
           Office  of Health and Environmental Research, Pollutant Characterization and Safety
           Research Division under Contract No. DE-AC03-76SF00098.  EPA support, und-r
           Interagency Agreement No.  DW8993 IS76-01-0 with DOE, was through the Office of
           Environmental Engineering Technology Demonstration, Office of  Research and



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
    (Springfield, VA: NTIS).

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).

Environmental Protection Agency (EPA), (1986a), Interim Protocols for Screening and
    Followup Radon and Radon Decay Product Measurements, Office of Radiation
    Programs, Report EPA 520/1-86-014 (Washington, DC: US EPA).

Environmental Protection Agency (EPA), (1986b), Radon Reduction Techniques for
    Detached Houses, Air and Energy Engineering Research Lab, Report EPA 625/5-
    86-019 (Research Triangle Park, NC: USEPA).

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), "The  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.

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

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, LA., 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).

Sachs, H.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).

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    Radon in Houses on  Florida  Phosphate Lands,  Report EPA  520/5-83-009,
    (Springfield VA: NTIS).

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    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).

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    (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, Minneapolis, MN, Paper No. 86-43.2 (Pittsburgh, PA: Air  Pollution
    Control  Association).

                         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
               Post-Mitigation Evaluation
  Monitor indoor air concentrations
  Measure mitigation system operating parameters
(improve system efficiency)
    modify system	
install additional options
                                                      XBL 871-8920

                                                 Figure  2

                                             Problem Diagnosis

              Replicated, 7-Day Average  Radon  Concentration in  Indoor  Air
                                   Heating  Season  Measurements
     Levels < 4 pCl/L on  all  livable HOCKS - No Action
 Levels > 4 pCi/L on any livable floor
       Conduci Building Survey
                                                    Figure 2A
               Non-Soil Sources
                            Characterize  Structure and  Identity  Entry  Points

i.) Conduct Visual Inspection:
   - Complete forms (sue and  lloor plans, elevations, housing surveys, occupant questionnaire)
   -  Probe likely entry  points (wail or lloor cracks and holes, masonry interlace,  block wall  lop and holes) using shit wiie.
   screwdriver, and smoke lubes.

2.) Grab Sample Indoor Air under Natural Conditions
   Collect alpha scintillation cell grab samples under existing natural conditions Irom each unique  building tone (garage. 2nd lloor.
   1st lloor. basement, crawlspace. slab-on-grade areas).

3.) Grab Sample Indoor Air under Mechanical Depressuriiation
   Collect grab samples  using  alpha scintillation cells Irom likely entry  points and various building tones (this sampling could be
   repeated 2-3 days alter the  lirst sampling to document the variability in the technique due to environmental (actors  or sampling

   Depresaunie house using blower door to -10  Pa in substructure lor > 30 mm. (may not cause representative distnbution of Rn
   throughout house)

   a) grab sample ol indoor air  from each separately delined room or zone at mid-height

   b)grao sample from cavities m bottom course ol blocks, approx. every 3 m  (10 fl.) (through existing or 0.6 cm (1/4 in.) drilled
     inspection holes - lit! holes on completion)
     grab sample Irom 2 to 4 holes through slab (through existing or 1 cm (3/8 m.) drilled inspection holes)
   C) grab sample Irom behind  lined walls every 3 m (10 It.) (Approx IS cm (6 m.) above lloor)

   d) grab sample Irom each obvious penetration to soil (condensate drains, lloor  drams, sumps, service penetrations, toilet and
     snower bases)

   e) grab sample Irom wall/door joints  Irom each wall (where accessible)

   I) grab sample Irom representative wall and lloor cracks and French drain cavities

     For el and 0. either:
     1) Tape over joint, crack  or French dram lor approximately 60 cm (2 It.) to either side ol sample location and seal ends m
       French dram, or
     2) Tapo or seal with sealant, plastic film over |Oini/crack. evacuate Irom beneath  film, ana  allow film »paca to charge with soil
       gfts b«lor« collecting »«mpl«.

    h| grab sample from other confined space in contact witti in* wills or now. sucn as framed will cavities
Count the activity lor eicfi simple (see tent) and identify on hou>« lloor plan. Samples with concentrations  < room concentration
are not  likely entry points, those with concentrations — 2-3 X room concentration are possible entry point], and those witrt concen-
trations  > 3 X room concentration are likely entry points.

4.)  Qualify Air Movement From Likely Entry Point*:
    Depressunte nouu to —30  Pa in tub structure to chanctenie  air movement Irom soil to house through entry points using
    Chemical smoke

    Check flow ah   substructure cracks, holes or joints in slabs or walls
                    lops ol biock wails
                    previously drilled test holes
                    between floors
                    exterior soil line
                    other potential entry points: sumps, drains, shower and toilet bases, service entrances and penetrations
5.)  Conduct Blower Doof Test! to:
    - meiiure me equivalent leakage area of:
• tne whole house
• substructure only
• superstructure only
    - identify large notes and bypasses between upper floors and basements that will ennance the SUCK effect

 8.) Observe Ventilation Communication Within Block  Wills and Beneath Slabs:
    - using nign vacuum (2 m: SO in. water) and hign flow (170 m'tr1; 100 ctm) blower, depressunze subslab region and measure
      pressure drops and determine e!r movement at likely entry points and drilled test holes,  including those m wills
    - attach blower to block walls and check for air leaks in the walls and the eitent ol Ihe induced ventilation at cracks and holes
      and drilled ten holes.

 7.) Observe Effect  ol  Appliance Operation:
    - using micromanometer determine additional depressuntation of substructure due to appiTince opereiion (dryer, •rurnice imoil-
      ance. fireplace, wood stove. e»hausl fan) by cycling appliance on/off for appro>. 20 cycles.
             Additional depressunzatlon > S Pa
                   Take corrective action
                             Additional deprenurizalion  < 5 Pa

                            ~~~-~—~ No jcnon
 8) Conduct Soil Tetts (optional):
    - i* Subsurface  or weeping 1iie ventilation may be considered  as mitigation options  conduct neif.nouse jo'il a'lf permeiailtry
      nil. and so'ii Ri test

                                         Figure 3

                                    Radon in Water
              Local Well Water?

• • i ea
\ Direct Test water
4J method I
Water sample analysis
Bath air gn

Cw < 40,000 pCi/L

No water
treatment necessary
Cw > 40,000 pCi/L
Operate Bath Shower 15 Minutes
to Obtain Closed Room Air Sample
  __  (Cfinal bath ~ ^initial bath) X ^bath (U
"  *    Fshower(L/hr)  X 0.9  X t(hr)

               *—+• Cw < 40,000 pCi/L
                                         C  > 40,000 pCi/L •*
                          Mitigation options:
                          - Aerate
                          - Filter
                          - Options: 10
                                  I  11
                   14-day average indoor
                   radon concentration measurement
      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

                                       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)?
— Yes
                                          Measure Rn flux

                               Flux rate (pCi/m2-hr) X material area (m2)

 V,   (L)
                          <2 pCi/L-hr
              >2 pCi/L-hr
                        No materials
                        mitigation action
           Mitigation options:
             - Remove or seal material
             - Options: 10
                                                        Materials mitigation
                                                       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 «-track film by occupant
                   • Periodic mitigation system maintenance by occu-
                                                                           XBL 871-8918

                                                               Figure 5

                                               Selection of Mitigation  Systems

                Alter  a careful review ol Ihe subslruclure(s). ilomizalion ol potential entry points, grab sample and air (low
                mapping, and occupant  comments on operation ol certain appliances, a mitigation plan should be developed.
                It should address control ol radon lor each house starling with one substructure type bolore moving lo Ihe
                next substructure type.  Crawlspaces (il they exist) are typically Ihe simplest lype  to mitigate and work should
                begin here il Ihe diagnosis so indicates.

   Other predominant substructure
   types or combinations
 Basement With  Poured Foundation Walls
 As indicated by mapping and inspection survey.
 Mitigation options:    1

• Basement With  Block Foundation  Walls

 As indicated by mapping and inspection survey,
 Mitigation options:   1    6      11
 Slab on  Grade                              	

 As indicated by mapping and inspection survey.

 Mitigation options:
         4   In addition, subslab heating system ducting may require
             sealing Irom occupied spaces and rerouting through attic.
         5   In addition, subslab heating system ducting may require
             sealing from occupied space and rerouting through attic.
                                                                                  Crawlspace concentration <
                                                                                  0.75 x occupied space - and less
                                                                                  than other substructure zone con-
       Crawlspace  concentration ~»
       0.75 x occupied space concentra-
       tion  or greater than other sub-
       structure zone concentrations

 Install 0.09 m1 (1 It1) uniformly distributed venti-
 lation/9 m* (100 ft2) floor area or install Ian sized
 lor 5 ACH to overpressurize lo  -10 Pa.  Install
 thermal  insulation.   Seal  between  Crawlspace
 and structure, including return air ducts.

 14-day average indoor  radon concentration
                                                                                  Indoor levels > 4 pCi/L
                                                                                   - Additional mitigation
Indoor levels  < 4 pCi/l - No additional action

•  Annual long-term follow-up indoor air measure-
  ments using ii-lrack film by occupant
•  Periodic mitigation system maintenance by occu-
                                                                                                                                                        XBLBM 8915

                                                Figure 6

                                        Mitigation  Options

1)  Sump sealing - active and inactive sumps
2)  Floor drain sealing - 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                                         B) Interior
    • If homeowner prefers exterior                        Gravel under floor slab
    • No landscaping  interference                          • Central ventilation point
    • No utilities interference                               every 45 m2 (500 ft2)
    • 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 floor (1 cm;  3/8 in.  diam.) and walls (0.6 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 size to < 500 m3rr' (300  cfm) (smoke tubes at
     inspection holes to verify extent of ventilation)
7)   Floor  crack sealing     • Where majority of 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 cell
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 occupied space.
     • In basement install 0.09 m2 (1 ft2) uniformly distributed vents to the outside per 4.6 m2 (50 ft2) floor area
      or install fan sized to 5 ACH  to overpressurize substructure to 10  Pa

Options not considered here :   Coatings
                               Soil removal
                               Air cleaning

                                                                                          Figure 7

                                                                              Post-Mitigation  Evaluation

                                            Measure: Temperatures and differential pressures in installed ducts, pipes: soil and building interior air (lows
                                                     developed by fans  in ducts and pipes; radon concentrations in exhaust air streams.
                                            Observe: Integrity of sealants, fillers, and bonding agents.  Noise and vibration of fans and blowers. Inspect
                                                     for leaks and bypasses in all systems.  Correct if necessary.

                                            Repeat grab  sample mapping survey and measure average indoor air concentrations for minimum of two
                                            days.                                              ,
                                                                                 Indoor levels > 2 < 4 pCi/L

                                                                                 14-day average radon measurement in
                                                                                 indoor air (heating season measurement)
                                                                                                             Indoor levels < 2 pCi/L

                                                                                                             Refine system operation until room air
                                                                                                             concentrations just begin to show an increase-
                                                                                                             then boost system operating parameters
                         Indoor levels > 4 pCi/L
         Grab samples <  indoor
         (room) concentration  •*-
         Grab samples remain > indoor (room) concentration (and
         pressure held is insufficient at likely entry points
         mitigation options 3. 4, 5, 6. 9)
                                        Indoor levels ;> 2 < 4 pCi/L - No turlher action
                                        • Annual long-term follow-up indoor air measurements
                                         by occupant (..-track film)
                                        • Periodic mitigation system maintenance by occupant
                                                          Reduce Blower Flows Approx. 50%
                                                              Mitigation options:
                                                                       3    9
                                                                       4    tO
                                                                       5    II
Increase pressure developed
  by blower npprox. 50%
   Install additional ventilation
points near remaining entry points
Increase blower flow rates
Mitigation options:   10    f"
Dlock-off Subsurface
  Ventilation Points
Mitigation options

Figure 6


Figure 6

Figure 6
                                                                                                                                                                               xni n?i Ron,

                         Figure 8

       Distribution of Structure Effective Leakage Areas
'-••••' •. *&:£?•• °t O-oi^'.. £?'
        ' * C*.S9.;..C ,. O • 0-V— ° -**
                                        oO-i3%^Oo/n'. •• **. «C

           Whole building (ELAJ =a + b + c + e + f

           Superstructure (ELA ) = a + b + c + d

           Substructure (ELAb) = d + e + f + g

           Substructure ceiling (ELAC) = d

           Substructure walls/floor (ELAf) = e + f + g
                                               XBL871 8921

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                                 Water conctntuhon
                                                                     -  llpCi/L
                                                                     »  12 pCi/L
                                                                     -  ?2pCi/l.
                                                                     > 124 pCi/L
                                                                     -  MpCi/L
                                                                     .141 pCI/L
                                 • 52 71 pCi/m* •

                                 -0371 pCi/m'i

                                 - 2tBpCi/L
                                                                                                                                                      Kay 10 Symbols
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                                                                           Subscript -                 O     DiagnoMica
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1.2.3^,  • Aib.lia»y atmpla  kxalton numb«


                    David Saum and Marc Messing
                  INFILTEC Radon Control services
                           P.O. Box 1533
                      Falls Church, VA  22041

How can guaranteed radon  remediation performance be provided at a
price that homeowners  are willing  to pay?   The paper summarizes the
diagnostic procedures  developed  by INFILTEC to achieve this goal.
Assumptions will be pointed  out, as well as problems and questions.
INFILTEC is submitting a  patent  on the  pressure/flow test equipment
and techniques described  in  this paper.


The customer seems to  be  willing to pay for diagnostics if it will
result in a better system installation  with a higher level of
confidence in the remediation.   Two to  three hours of diagnostics may
be an upper limit on time, with  a  corresponding cost of $200 to $300.


The radon source is assumed  to be  primarily under the slab ar.d at
levels 10 to 1000 times the  levels in the  air.  Walls, whether block
or concrete are assumed to not be  a problem unless the source mapping
does not show any significant levels.   Source mapping consists of
drilling approximately 5  small holes (one  at each corner and cne in
the center) and counting  a Lucas cell for  5 one minute intervals while
puir.ping subslab air through  the  cell.   The cell is allowed to clear
for two or three minutes  between holes.  If wide deviations in levels
are noted, or the slab is  complex  in shape,  or the slab is large, then
more holes may be drilled and tested.   Although the radon counts do
not allow for daughter equilibrium,  the relative levels around the
slab are of most interest and the  actual levels are assumed to be 1.5
to 2 tines as high as  the  count  indicates.  The combined time for
drilling the holes and counting  is approximately one hour.  When the
source mapping is completed, the slab areas of most interest (highest
radon) should be known.   Drains, sumps, and crawl spaces are also
tested similarly.  Walls  are only  tested if the subslab levels seem
too low to account for the previous screening and confirmation
measurements by the homeowner.


Sub-slab suction is assumed  to be  the primary radon  source
remediation technique  which  should be attemped if at all possible.
Radon is assumed to be prevented from entering the house if there is
an adequate pressure barrier at  the slab.   Wall suction has not been
found to be necessary  in  any houses. Some houses have been
encountered that have  not  been remediated  yet, due to complex
construction that makes sub-slab suction difficult.

       The work described in this paper was not funded by the U.S. Environmental
       Protection Agency. The contents do not necessarily reflect the views of the
       Agency and no official endorsement should be inferred.



 A  portable  suction system with flow and pressure gauges (blower  floor)
 is installed in  a  1"  diameter drilled hole or a sump hole  that  is  near
 to the  radon concentrations and is also near a good venting  location.
 Selection of a good suction point involves many cosmetic,  venting,
 radon source, and  customer considerations.  The fan for the  suction
 system  is outside  to  avoid worker exposure to high  radon
 concentrations,  and a long flexible tube is used to connect  the  fan  to
 the  suction hole.   Note that apha-track measurements taken during
 months  of almost daily diagnostic and remedial work,  show  radon
 exposures below  4  pCi/1.   Two types of measurements are made: flow
 versus  pressure  in the hole, and pressure in the suction hole versus
 pressure  in the  test  holes around the slab.  If there is no  pressure
 induced in  the test holes by the suction hole pressure,  other  suction
 holes may be drilled  on the assumption that the suction hole was in  a
 dead spot.   If the suction hole pressure induces large pressures at
 the  perimeter test holes, then the flow has been shown to  be good, and
 tight enough to  induce pressure with standard fans. Cases  of marginal
 pressure  and flow  require further analysis.


 Simple  rules of  thumb are assumed to determine the  minimum adequate
 pressure  across  the slab.  Houses are assumed to be so leaky that
 stack pressure is  the dominant cause of suction on  the slab.  The
 neutral pressure point is assumed to be in the attic,  and  the stack
 maximum stack pressure on the slab is assumed to be approximately
 0.001" WC per foot of building height.   This leads  to an approximate
 rule of thumb of 0.015" WC of suction for the design  pressure in a
 typical house.   This  is the worst case pressure to  be exerted across
 the  slab.   Actual  measurement of stack and appliance  induced pressure
 are  complicated  and do not seem to be necessary in  most cases.


 When marginal flow and pressure measurments are encountered, the
 capability  of a  particular fan/pipe system to achieve adequate edge
 pressure  can be  calculated from measured pressure and flow data.
 Section 11  of this  paper  gives a sample of this type  of  calculation.
 It allows tradeoffs to be made between fan sizes, pipe,  venting, etc.


 The  installed sub-slab system must  be carefully checked  to determine
 if it actually achieves the required pressure field across the slab
 and whether  is has  leaks  that could cause radon inflow back  into the
 house.  A separate  quality control  visit is made after the system  has
 been operating for  a  least 24  hours.      A pressure  gauge is
 permanently  installed  on  all  remediation systems to allow  contractor
 and the homeowner  to quickly  verify proper fan operation.  Freon is
 injected  into the  system  while  the  fan  is on and a  freon leak detector
 is used to detect  leaks in the  fan,  pipe and vent location.  Radon
grab samples are taken  to measure  remediation performance  and the
homeowner is given  charcoal  and  alpha-track test kits.



Mt. Airy
Owings Mills
Mt. Airy
W. Bethesda
Silver Spring
Owings Mills
Split Level
Split Level
100 pCi/1

    3.3 pCi/1
The readings before remediation may be summer or winter charcoal
tests in the basement, but the readings after remediation are all
winter charcoal tests in the basement.

* reading after 1st stage remediation on house with slab on rock.


Very few remediation contractors are now willing to buy the full range
of equipment that these diagnostics require.

    * Continuous Radon Monitor ($3500-54500)
    * Rotary Hammer and other tools ($300-$600)
    * Pressure Gauge (Analog model $60, Digital model $600-$1400)
    * Blower Floor (Analog model: $2500?, Digital model: $5000?)
    * Freon Leak Detector and Freon ($150-$250)

             TOTAL COST RANGE: $6500 to $12000


 The objective  of  this  calculation  is  to predict  the  pressure  that  will
 be  induced  under  the slab by  specific fan and  pipe configuration.   The
 calculation requires formulas for  the pressure/flow  characteristics of
 the fan,  pipe  configuration,  and the  subslab.  The fan  and  pipe
 formulas  are available but the subslab characteristics  must be


 Flow/Pressure  Measurements By INFILTEC Blower  Floor:

  ("WO          ("WC)           (CFM)

 0.136          0.150             83.27
 0.120          0.134             78.70
 0.100          0.110             71.31
 0.090          0.095             66.27
 0.080          0.082             61.57
 0.060          0.058             51.78

 These data  then can be fit to a power law flow equation with  the
 following results:

      * Correlation Coefficient = 0.998
      * Flow Exponent (N)  = 0.581
      * .Flow at 1  " WC  = 268.6 CFM
      * Effective  Leakage  Area (ELA) = 12 square  inches

 Note  that this basement is 25'  by  40' with a perimeter  of 130'.   If we
 assume that all of the leakage is  due to the perimeter  crack, then
 this  crack  has a  predicted width of about 0.008".

 Now that we have  a formula relating subslab pressure and flow, we  can
 write an equation equating the pressure generated by the fan  to  the
 pressure  loss  in  the pipe and in the  subslab:

    Fan Pressure  = Pipe Pressure Loss + Suction  Hole Pressure Loss

 This  equation  can be solved for flow, and this flow  can be  used  to
 evaluate each  pressure component.  Suppose we  assume the following fan
 and pipe characteristics:


 Kanalflakt  T-2 fan specifications  can be written as  the
 following equation:

        Q = 270 - 116P

 where  Q is the  flow  through the  fan in CFM
        P is the  pressure across the  fan in "  WC


 Consider a system with ten feet of 4" diameter PVC with one 90 degree,
 one vent cap, and one screen.  An approximate equation for air flow
 through a smooth round pipe of length L and diameter D can be derived
 from handbook graphs:

         Q = (.027LD EXP(2.75)) (P EXP(.55))

 where  Q is the flow through the'fan in CFM
        D is the pipe diameter in inches
        P is the pressure drop in one foot of pipe
        L is the length of the pipe in feet

 Assume an equivalent pipe length for resistance of pipe components:

       one 90 degree Bend = 50 pipe diameters
       one vent cap =       50 pipe diameters
       one screen =         50 pipe diameters

  Equivalent Total length =  150D/12 + 10 = 60 feet

 Solving for pressure:

      Fan Pressure =             (270 - Qj/115
      Pipe Pressure Loss =       (Q/(.027LD EXP (2.75)) EXP (1.818)
      Suction Hole Pressure =    (Q/C) EXPd/N)

 Substituting into the subslab system equation:

  (270 - Q)/115 = (Q/(.027LD EXPC2.75)) EXP (1.818) + (Q/C) EXP(1/N)

 This equation can be solved interatively for Q:

       * Steady-state flow = 141 CFM

 And the flow can be used to solve for the component pressures

       * Fan Pressure           = 1.11" WC
       * Pipe Losses            = 0.78" WC
       * Suction Hole Pressure  = 0.33" WC

 This compares well with the measured 0.35 " WC subslab suction
 generated by the installed system.

 The pressure at the suction hole can now be used to estimate the
 worst case pressure induced across the slab,  far away from the suction
 hole (called the "edge pressure").  In this particular basement,  the
 edge pressure was .020" WC when the pressure of 0.25 " WC was induced
 on the suction hole by the blower floor.  In some cases,  the realation
 between the suction hole pressure and the edge pressure is linear, but
 in others it is not and in those cases the edge pressure  must be
 predicted by finding a curve fit between it and the suction hole


             This paper has been reviewed in accordance with the U.S. Environmental
             Protection Agency's peer and administrative review policies and approved for
             presentation and publication.

                       AND DOES IT MEET THE GUIDELINES?

                              Kenneth J.  Gadsby
              David T.  Harrje, Lynn  M. Hubbard and Craig  Decker

                 Center  for  Energy and Environmental Studies
                 Princeton University, Princeton,  NJ     08544

     Many of the diagnostic  procedures covered by the other presentations in
the Radon Diagnostics Workshop must  be employed before  a  choice of mitigation
method is made.  We will not review  each  of  these procedures  but rather will
touch briefly on items that  have  not been included in the other presentations.

                  Infrared scanning  of interior surfaces
     This diagnostic technique is used to uncover air leakage sites  and air
flow patterns within the building.   Outside  air is normally a different
temperature, colder  or hotter, than  interior surfaces.  When  this outside air
enters the building  it alters  the local surface temperatures  and thus can be
detected with an infrared  scanning device which is sensitive  to small changes
in surface temperature.  Air flowing upward  in the home from  a cooler or
warmer basement environment  again results in alteration of interior  surface
temperatures.  If the blower door is used to increase the upward air flow
(operating upstairs  in the  depressurization  mode) the air path is made even
more evident.  Since this  is likely  to be a  pathway  for radon transport,
the IR technique can prove useful in documenting  such radon paths as well
as evaluating how well separated the living  space is from the
basement/crawlspace.  This  degree of separation may  directly  affect the
choice of mitigation method.

                         Tracer  gas  measurements.
     Flowpaths, as just  described, can also  be evaluated using a tracer gas.
The tracer gas is injected into  the  basement or  other radon source locations,
and the path that air takes  is then  determined from  local measurements, over
time, of the concentrations  of the tracer gas.  The  tracer gas detection
equipment may take a variety of  forms from  simple freon leak detectors to
portable gas chromatograph  electron  capture-based devices.  Cost may vary from
$100 to more than $5,000 per detector.

     Another application of  tracer gases  is  for evaluation of the air
infiltration/ventilation rate  in the house  or zone.   One method is to add a
tracer gas, allow it to  mix  with the air  in  the space (natural convection
helps the mixing process,  and  running the furnace blower normally achieves
the mixing in less than  10 minutes), and  then monitor the decay in the
tracer gas concentration levels.   This "decay method" or "dilution method"
(see ASTM Standard E779  for  details) allows  one to directly determine the
air exchange rate, i.e., the faster  the decay the higher the  rate.  Another
method, such as "constant  injection" of the  tracer gas, may employ tracer
emitters and passive samplers  to  evaluate the air infiltration rate.
Several different tracer gases can be used with this method so that flow

from zone-to-zone can be measured.  If each zone is maintained at a
constant tracer gas concentration, i.e., the "constant concentration
method",  flow rates are then directly proportional to the tracer gas flow
rate to each zone.  Systems are available to measure air infiltration rates
in 10 zones simultaneously.  Rather than porbable diagnostics equipment,
this is computer-controlled ventilation monitoring equipment, priced in the
$20,000 range.

     All of the methods described above evaluate building tightness and flow
paths and therefore may directly influence the choice of mitigation device.

            During and after the mitigation device is in place.
     The preceding discussion on diagnostic techniques is useful for choosing
the correct mitigation approach.  Now we wish to shift attention to what
should take place during and after the mitigation device is in the house.
Mitigation installation diagnostics are important to see whether or not the
equipment is working correctly.

     During installation of a mitigation system, such as subslab ventilation
where one is exhausting radon-laden air, adding a tracer gas to that air
allows one to evaluate where leaks in the system may be occuring, and whether
or not exhausted air is being carried back into the house.  Of course the
radon itself serves as a tracer but the measurement equipment tends to be less
portable and more expensive than using freon and a freon leak detector, for

                               Flow balance.
       Many of the mitigation devices rely on withdrawing radon from critical
areas such as under the basement slab.  Such air movement is governed by the
standard flow relationship, namely:
                                 Q oc A  y delta P

where Q is the air flow rate, A is the area for the flow passage and delta
P  is the differential pressure.  This means that if the air passage is non
restrictive, i.e., A is large, then a small differential pressure may be
all that the system can provide when the exhaust fan is flowing at its
rated Q value.  On the other hand, if A is very small, delta P will become
very large and the rated Q may not be reached since the fan will stall, or
run very inefficiently.

     Since there  is often more than one branch to the mitigation system
piping, one wishes to make certain that all the critical radon source areas
are being appropriately treated.  For example, in a house with a subslab
system treating a basement slab and crawlspace slab, one wishes to balance the
system so that both slabs are being treated equally.  In the case of high
radon spurces in  one area, that particular area should receive the higher
     Diagnostic methods involve flow measurements in the various duct branches
using heated wire anemometers, pitot tube and micromanometer, or other  flow

measurement systems  that  can be easily inserted into the piping.  Provision
for dampers in the piping lends itself to rapid flow adjustment of the
branches.  Measurement of the exhaust for radon concentration level can
also help determine  the best adjustment or balance of the system.

                       Energy and Radon Mitigation
     Once the radon  mitigation system is working satisfactorily from a
radon reduction point-of-view, it is then worthwhile to consider other
factors.  Lowering the fan speed, providing the radon concentration in the
home does not rise,  offers an ability to save energy in two ways:  first
the fan electrical energy is reduced and second one limits the energy loss
assocaited with the  conditoned interior air that is exhausted with the
radon laden air.  From a  diagnostics standpoint, energy savings from either
a lower fan speed or smaller fan can be determined by the use of a
wattmeter.  The evaluation of how much additional air is being removed from
the house must rely  upon  air exchange measurements using tracer gases.  For
example, placing a tracer gas in the basement and measuring the
concentration there  and then measuring the concentration in the exhaust
from the subslab system allows an evaluation of how much of the air was
basement air and thus to  evaluate the energy penalty.  It is evident from
test home data that  exhausting systems do alter the "normal" air
infiltration rates and raise energy use.  This often can be limited to a
minor increase by appropriate mitigation system adjustments.

     When mitigation systems are used which cause air to leave the
basement, we must be sure that the air flow is not causing a pressure
reduction that results in combustion products from the heating system to be
•drawn into the basement and home.  Use of heated wire anemometer, pressure
micromanometer, and  smoke tracers can prove useful diagnostics tools for
evaluating proper flow direction in the furnace exhaust.  Remember that the
greatest tendency for reverse flow will be under mild weather conditions.

     Also, where the piping of the mitigation systems leaves the
conditioned space, the opening must be completely sealed to avoid
undesirable energy losses.  Use of smoke sticks, tracer gas or IR scan will
immediately revel such shortcomings.  In the same area of "good
installation" the system  piping must have the appropriate slope so that
condensing moisture  will  not form a local puddle and plug the exhaust flow.
This is a very real  problem with large volumes of water being condensed.
Use of bubble levels and  careful measurements and firm bracketing avoids
these difficulties.

     This has been a very brief review of some additional diagnostic
procedures that should prove useful in the choice of the mitigation approach
and whether the mitigation system is performing as desired.  Diagnostic
techniques are focused on providing quantitative and qualitative data to
improve the chances  for successful radon mitigation.  At times  the most
critical procedure will prove to be something very house specific, meaning the
investigator must continually ask critical questions and ponder  those
measurements that "don't  make sense" while looking for the  "right


     The following are the actual discussions that took place in the

Workshop as transcribed from audio tapes.   Efforts have been made to

identify the originators of question (Q),  answers (A), or comments  (C).

This identification is by initials in the parenthesis before each quotation.

Please refer to the list of attendees for this information.

       As has been the rationale throughout this Workshop the discussions

will be treated in four phases:

     I.    Radon Problem Assessment

     II.   Pre-Mitigation Diagnostics

     III.  Mitigation Installation Diagnostics

     IV.   Post-Mitigation Diagnostics

Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
                       M. Mardis, Chairman
C(M.M.)  "Phase I is the Initial Radon Problem Assessment and we want to
focus our attention on diagnostic tools that will prove useful to identify
radon source strength and location; to characterize the existing building
structure; evaluate occupancy factors; and measure the radon concentration
in the different zones within the structure.
     The panel will begin the discussion, and we will start with mobile
scans with Mike Koontz:
C(M.K.)  "I would like to start out with a few background comments about a
statewide survey in Florida.  That is, I'll start with a regional
perspective and lead into the specifics of a house."
     "The purpose of the Florida study is to identify areas of the state
which are problematic in terms of radon.  There is an environmental rule
there that basically states that if an area is declared to have problems
then certain types of radon-resistant construction methods are to be used in
new construction.  In that study we're measuring radon indoors, short-term
with charcoal canisters, and measuring soil gas concentration.  We're also
using portable scintillometers to measure radiation instantaneously inside
and outside the houses."
     We're guiding our survey as to high-concentration areas with USGS 1-
24,000 scale maps representing 8 mile x 8 mile squares (quad) of land.  We
originally thought that as we had our field techs going from one place to
another searching for houses and making these measurements it might be
useful to use these portable scintillometer to make measurements while
driving to give us a better feel for  local variations.  Unfortunately we
found that the road surface was a confounding factor, and we couldn't make
reliable measurements that way.  This leads to my question with respect to
measurements from mobile vans:  what  sort of false positives might you see
due to road surface or other potential confounding factors?
     "Alan spoke about mapping data from NURE or other sources.  We've found
that the 1:24,000 quad is a convenient mapping tool.  We've looked at the
NURE data, not only the radiation values, but another possibly valuable
addition from the NURE data is that they do have so-called geologic map
units associated with each reading.   Again, bearing  in mind that at least in
Florida, flight lines are sometimes 18-20,  miles apart, depending on
whether you're looking N-S or E-W.  Nonetheless, the  1:24,000  quad can be a
convenient way of looking for subcountry variations  at a gross level.  The
NURE data, both the brightness and the geological data, seem  to be helpful,
and we're seeing also that there are  fairly good correlations between soil
gas' concentrations and indoor concentration, again,  at this more aggregate
level.  I don't think it works at the neighborhood  level,  looking at house
to house variations.
     "These state-wide data can be used  to  identify  potentially  "hot" areas.
Within a given area there may be variation  of an order of magnitude."
Q(T.T.)  "During your work in Florida, you  did gamma surveys.  We've heard


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
here that some studies have shown that gamma and other emanation studies in
some parts of the country (like Grand Junction, Colorado) are usefully
correlated with Indoor levels, but that in other areas (such as in the
Reading Prong) the case is not so straightforward.  What experience did you
have in Florida?"
A(M.K.)   "We haven't analyzed all the data yet, but we did see that the
strongest correlation of indoor radon concentrations is our soil
measurements made with alpha tracks.  We do see some correlations, even
indoors, between concentrations of uranium and radon, but we're not in a
position yet to say how well It works."
Q(   )  "How are the soil measurements made?"
A(  ) "Without the traps they're in 12 to 15 inches."
Q(  ) "What kind of correlations are you getting?"
A(M.K.)  "The correlation coefficent between soil measurements and
Individual houses has been 0.5, whereas using the quad as a unit of analysis
with the soil measurements, the correlation coefficent has been 0.7.  We've
taken measurements in, say, 4-6 houses per quad.  0.7 is the correlation
between mean soil concentration and mean indoor concentration.  Q(M.M.  )
"Do these houses have basements?"
A(M.K.)  "This becomes an issue when one is doing mass screening using
charcoal canisters indoors and looking for problem areas.  Ideally one would
be  able to identify a "marker house" of a design found throughout the state
so  as to avoid the confounding effects of measuring in houses of completely
different construction types.  Fortunately, in Florida, perhaps 75% single-
family homes are slab-on-grade, so we've restricted ourselves to that type
of  structure."
Q(D.S.)  "I'd like to focus in on that correlation.  The correlation is
acceptable, but is it really the soil gas and source strength?  Or, is  it
that plus the transport in the sort of homogeneous conditions found in  all
your houses?  We are getting closer to the "radon availability index".  The
reason that you got a good correlation may be not only that the soil gas
level is related, but that it is available because of the transport
A(M.K.)  "I agree, and we might want to follow the dual method Alan Tanner
suggested which measures soil permeability as well as sour strength,"
Q(   )  "How many alpha track soil measurements did you make?"
A(M.K.)  "We did one per house for about 3000 houses."
Q(T.T.)   "Where did you put it in relation to the house?"
A(M.K.)  "It's fairly close to the slab, perhaps three inches away 12-15
inches deep.  We also take scintillometer measurements at that same
location, and at a location on the opposite side of the house.  We've seen
substantial variation between the two sides of the house in those
instantaneous radiation measurements."
C(W.L.)  "Someone commented this morning that you have to go down at least a
C(A.T.)  "I did some work in Hillsborough and Polk Counties in Florida,
where the [radon] problem is the worst, and Florida is really quite unusual.
Often one will find 10 or 20 feet of well-sorted  (in other words, the grain


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
size is fairly uniform) pure quartz sand, in other words, a very uniform,
homogeneous soil.  The soil is of pretty high permeability -- it's pretty
fine stuff, but it's well sorted.  The diffusion coefficient is probably
very characterizable and the permeability is reasonably so.  The water table
can come right up to the surface, or it can be down a ways, so there will be
seasonal changes in dryness and wetness.  But in comparison with most areas
of the country, the soil is the ideal, almost the physicists' mode of
homogeneity.  Under those circumstances, placing track detectors at that
shallow depth is probably not unreasonable.  At some point I'd like to get
into a discussion of the use and abuse of track detectors."
C(D.S.)  "It is important to say why measurements agree or disagree as we
discuss these points."
C(R.S.)  "So, Alan, you're saying that it's not surprising that one sees
some degree of correlation, at least at a gross spacial scale just because
it is so uniform. David made the point earlier that if it's pressure-driven
flows into the house (and of course you're not really seeing that with alpha
track detectors buried in the soil --at best you're seeing diffusive
C(A.T.)  "This may be the time to talk about alpha track detectors."
Q(T.T.)  "Is it true that the bulk of your studies in Florida is on tailings
and reclaimed pits?"
A(M.K.)  "We're actually doing uniform coverage of the state."
Q(T.T.)  "I was down there in the early seventies to study housing built on
a reclaimed pit.  I was surprised to find that my hotel room in Lakeview was
hotter than the housing I was studying.
Q(D.S.)  "Are there other experiences with the use of alpha track soil
A(I.N.)  "When Teradex first came out of these kits, we sent them to 60
homeowners in central New York,  and put four monitors around each house.  It
was very simple and inexpensive.  Simultaneously we put three alpha tracks
in the house itself as well as in the water, in their toilet. We found
absolutely no correlation of any of the radon measurements in the soil nor
the indoor measurements.
Q(D.S.)  "Can you give us some specifics as to the placement in the soil?"
A(I.N.)  "It's the same technique: 12-18 inches into the soil, about three
feet from the foundation, as specified.  This may not have been a good
Q(D.S.)  "Tom Peake, could you speak on this issue?"
C(T.P.)  "The office of Radiation Programs of the EPA has  a program called
the House Evaluation Program.  We are taking some work that ORD is doing
with the research in mitigation, and applying it to the private sector.
These houses provide us access to homes which have been fairly well
diagnosed.  We're taking some soil gas measurements around the houses, 4 to
5 feet from the foundations.  We are using grab samples, similar to what
Alan has been doing; he's working on a  soil gas protocol for us.  We're
taking the information which he's giving us with help from Jay Davis.  We
took measurements near houses and away  from houses, three  ft. and 15 feet.
We found generally an increase in soil  gas concentrations  away from the


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
house.  We did not get a good correlation between radon soil gas values and
indoor Rn levels though correlations were positive.  We had one house with
550 pCi/L in the basement, and an average of measurement of 800-900 in the
soil, 15 feet away from the house.  Maximum levels were higher than that."
Q(D.S.)  "Do you have alpha track measurements as well?"
A(T.P.)  "We have some alpha track measurements, but results are not back
yet.  We had some problems with moisture condensation on the alpha tracks.
And I know Charlie Kuntz from New York had trouble with the water table
going up into the alpha tracks.  We also had trouble with atmospheric
dilution because of the way the dirt is settling."
C(M.M.)  "Tom brought up that in making alpha track or charcoal
measurements, in fact any type of soil-gas measurement, one has to take into
account the influence of the house.  He noticed that soil gas radon levels
increase with distance from the house, and that there is a lot of
C(R.S.)  "Looking at Figure 9 of a house, we see where grab samples were
taken from a soil probe, usually a meter of 1.5 meters deep.  We see levels
of 300-500 pCi/L at one point.  Around the house the house the numbers vary
to 89,000 pCi/L.  Back fill questions, location of concrete slabs, and other
factors account for three orders of magnitude variation."
Q(   )  "Has anyone taken soil moisture content measurements at the same time
that they took soil radon gas measurements?
A(A.T.)  "I can show some related material."
Q(M.M.)  "Let me use that question to take a step into another area, still
dealing with soil gas measurements, but in the area of mapping of radon soil
gas.  The question is mapping radon soil gas permeability and moisture and
how  these relate to one another."
Q(R.S.)  "Another question:  You've been taking measurements, both alpha
track and grab samples, and you've discussed confounding variables, such as
moisture.  Could someone comment on what other confounding variables might
affect the placement or depth at which you grab a sample?"
A(R.S.)  "If you get down below a meter or a meter and a half, you lose that
confounding variable, except in really permeable soil."
Q(D.S.)  "But Rich, could you comment on other confounding factors.  We're
talking about diagnostics, about how you can get really meaningful
measurements.  One factor is depth of placement and another is water and the
water table and how they affect the measuring device.  Are there others we
should point out now?"
C(A.T.)  "Not just the depth of the water table, but the percentage
fractional  saturation of  the pores is an extremely important  factor  in both
diffusion coefficient and permeability."
Q(D.S.)  "Is there an estimate as  to how these connections are made?"
A(R.S.)  "It's important  to note  that moisture does two things:   it
increases the emanating fraction  (or emanation ratio,  if you  want  to put  it
that way).  But at large  enough moisture saturations in the soil,  it
decreases convective flow through  the pores because as you begin  to  fill up
the  large pores, you lose your convective flow pathway."
C(A.T.)  "These data are  actually  Roger's... the moral  of all  this  is  the


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
following:  In theory in dry, porous media, the diffusion coefficient is
independent of pore size and the grain size, as long as you're within the
mean free path of radon, which is quite small.  But in the real world, the
diffusion coefficient drops rather dramatically as you, (looking at chart:
these are all orders of magnitude now and this is the diffusion coefficient
in free air)... as fractional moisture saturation increases, you get a
change in the diffusion coefficient of four or more orders of magnitude.
Even in principle, you get the same drastic change in permeability as you
increase the moisture concentration, and both of these are strongly affected
by... if you were to think of the water in the pore space as merely
occupying the space the air would otherwise be in you'd have a curve that
went something like that... and only when you get down to nearly complete
saturation would you have a marked change in diffusion coefficient.  The
answer is that the water, via surface tension primarily, tends to block
inter-pore communication, and therefore the water has a disproportionate
     "Now I can get back to the question of alpha track measurements.  I
have to say that my views are not necessarily those of the Teradex
Corporation.  This is an experiment conducted by Willashevitz and Pyrictonov
in 1959:  they had a sealed tube, with ports for examining the concentration
of radon in an open space, but in this otherwise closed tube, at various
distances along the length of the tube.  It was radium-loaded sand, and a
measured diffusion rate d/porosity measurement of .0134 cm2/second, and
these data were taken at steady state.  Now think of this as a track
detector cup over a column of earth.  What it shows is that the track
detector cup to some degree is actually performing an exhalation measurement
on that porous medium.  This .0134 cm2/sec is a fairly good diffusion
coefficient, not quite as high as that of nice dry sand, but it's a good
deal more than that of a lot of sandy clay loam; for instance, in which the
curve would look much more like this... The implication here is that as the
moisture concentration varies, the concentration of radon reflected in the
track detector measurement is going to vary considerably, even though the
actual radon production and the radon value in the pore space is remaining
constant, or even increasing slightly.  So, you do not get a real
concentration measurement using a track detector in the ground, or in a
porous medium.  Now there-is a modification here, because while this is a
strictly one-dimensional situation, in real life there would be
contributions from the side.  So, the situation would not be as drastic as
implied by the experiment.  But you do have to remember that you are looking
at a cross between a concentration measurement and an exhalation measurement
that is going to be very drastically affected by moisture in the ground, and
which is going to show seasonal variation and variations due to sudden
precipitation and so forth.  The closer you are to the surface, the worse
the situation is going to be."
Q(M.M.)  "Let me ask you a question about the moisture effect on the alpha
track.  Your chart shows some concentrations differences based on moisture.
What scale are those?  Are we talking about differences of 10% as moisture
changes, or are we talking about 50%?"


Radon Diagnostics Workshop, 1987-  Phase 1 Discussion.
A(A.T.)  "I would think that changes of 50% would be more typical."
Q(M.M.)  "Would you say then that based on that and on typical moisture
ranges that the alpha tracks would not be a useful tool?"
A(A.T.)  "There are two considerations.  One is how you use it, and another
is how you interpret the information you obtain from it.
     "There is even another caveat, though, an important one:  this study
was done for completely different reasons by ChrisJensen and Mumquist, and
what they had here were results from two holes side-by-side, and the one on
the left-hand they made track measurements where the cups were used at
successively greater depths, and back-filled so that there was no
competition from the atmosphere, i.e., no atmospheric dilution.  In the
depth range down to six meters they have (although there is a lot of scatter
in the data) a monotonically increasing radon concentration with depth.
     "In the left-hand experiment they had the track detector mounted in a
thimble that could pull up out of the ground after the experiment.  That's
rather'difficult to do and Charlie Kuntz, in his presentation, had a control
over the atmospheric dilution.
     "In the right-hand experiment they merely drilled the hole to a given
depth, put the track detector in the bottom and did not back-fill it behind.
What you see is that as you go down in the ground, the permeability
decreases, both because of moisture increase, and because of increased
packing of the ground with depth, and the atmospheric dilution takes over,
so that you get very low results.  This is strictly an artifice, and means
nothing.  If you put track detectors in the ground, you've got to back-fill
them.  I was thinking about what happens when the track detectors are
sampling a variable information volume.  It may be that that's a saving
grace and in fact a pretty good way.  It's been noted for a long time that
track detectors are an integrating device, and integration is general for
soil measurements is very desirable.  There are some data indicating that
there is a seasonal effect of a factor of five.  But, if in fact, the
measurements from the track detectors are a function of variation in
permeability and in the diffusion coefficient, maybe that's a good thing,
maybe you do iron those things out, and get a better measurement.  The one
thing I would advocate is that people reduce the size of that open space.
This may cause trouble with moisture on the surface of the track detector,
but I think that it's worthwhile to consider experimenting with something
smaller than the typical track detector cup.
C(  )  "There have been some studies done comparing grab samples, alpha
tracks, etc.  I have here a Swedish paper which describe traverse with
charcoal, alpha tracks and then the grab sample.  From the information it
looks like the different instruments measure the peaks at the same place.
However, the magnitudes of the peaks are different in every case.  So, I'd
like to caution everyone that even though it looks as though these different
devices might have some potential for measuring radon soil gas, only  the
grab sample can be used to get a permeability measurement which is
important.  Also, we should remember that when someone says they've measured
soil gas measurement of 1000 pCi/L with an alpha track detector, that may
not mean the same thing as the same measurement made with a grab sample.


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
Many people have been using a classification method developed by the Swedes,
under which an area with 1350 pCi/L would be considered a high-risk area.
We don't think that we can use that method as is.  In the near future we
hope to compare some of these different types of measurements around houses
among themselves.  We've already had a contractor do a little work, and his
results are similar to the Swedes: that different types of instruments can
be used, but that one must be careful about the configuration of the
instruments and their use in different situations.  We need to improve the
protocols for the use of these instruments, because at the present time
everyone is using them in different ways.  We need to know how these
different measurements relate to one another."
Q(M.M.)  "That's a good point... we've talked about the direct, Lucas-cell
type measurement, and about alpha track measurement.  There's a third,
fairly common type, which is the charcoal canister.  After we discuss that a
moment, I'd like to see if we can agree on a standard soil gas and soil
permeability technique, based on the experience we have among us in this
room.  Which is the most simple, best technique?
Would someone like to comment on the use of charcoal devices for soil gas
A(   )  "Why don't you talk about Vern Rodgers' experiments?"
A(   )  "In essence, Vern Rodgers compared charcoal canisters to track etch
and  grab samples and found that data from the charcoal canister (the same
ones we use indoors) did not properly represent  the levels of radon actually
found in the soil because the charcoal canisters  acted as a sink for radon.
You  weren't measuring the actual behavior of the  soil.  The Swedes, in the
paper cited earlier, found that charcoal canisters gave the lowest soil  gas
concentrations of any of the methods.  Moisture  can also be a problem with
charcoal canisters."
Q(M.M.)  "Were these side-by-side measurements for which the charcoal
canisters gave lower values than the alpha tracks?
A(   )  "There's also variability in all the measurements."
Q(   )  "How much lower are the readings from the  charcoal canisters?"
A(   )  "20-50% less would seem typical.  It's not that charcoal canisters
can't be used -- it's the way they are configured now."
Q(M.M.)  "What is standard canister out there now?"
C(R.S.)  "If you dig a hole you can put a pipe in the ground more  easily.
If you have a major soil gas radon concentration why not use a grab sampler
or something?  You can do it, because you can put a pipe in the ground just
as easily as you can dig a hole."
C(A.T.)  "The contention there is that you have  temporal variability.  How
do you get around that?"
Q(T.B.)  "We've talked about grab samples and alpha-track detectors.  What
happens with soil gas concentration as time goes  on and how do we  get a
handle on that?"
A(W.B.)  "It appears that seasonal variations are stronger than day-to-day
variations, at least as compared to indoor radon levels.  That seasonal
variation is going to have a lot to do with where you are measuring.  If,
for  example, one measures where the soil is frozen for six months  of  the


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
year, soil gas values will be higher.  But in the summer, soil gas values
will be lower.  It basically follows the same path as indoor radon levels.
For instance, you would get very different soil gas values in Florida, where
the soil does not freeze, than you would in New York or Pennsylvania.  We
have to watch out for freeze and thaw conditions because of elevated soil
gas levels.
C(D.S.)  "I'd like to interrupt.  We're trying to address the accuracy and
precision of different approaches, including alpha track, grab samples and
carbon canisters.  I'd like to outline how good those measurements are.
We've tried to address some of the confounding variables.  There may be more
variables confounding carbon measurements than the other methods.  We also
heard about the short-term vs. long-term integrating effects of these
methods.  Let's try to keep the discussion focussed on specific points
before we move on."
C(M.M.)  " To finalize our discussion of soil gas measurements, I've heard
several discussions about differences between the three techniques.  About
five months ago in Washington there was a meeting of people heavily involved
in making soil gas measurements.  We agreed that the simplest and  most
straightforward method is the direct measurement.  I think Alan was touching
on that when he suggested that a pipe be driven into the ground.  The direct
method is the most representative and gives a real value.  One disadvantage
is that it doesn't give you information on time variability.  Another point
is that once you have a measurement of Radon in the soil, there still
remains the question of how easily the radon can move or migrate to a
structure.  In short, we mean permeability.  Can someone factor those two
together for us?"
A(A.T.)  "Well, they are the factors.  Permeability is not the only one of
course; diffusion is a valid method of motion, and I think that because of
the  aggregate below the slab, diffusion may in fact contribute more than we
think  to the reservoir which that aggregate layer makes up.  The process is
then diffusion into the reservoir and then when you get an underpressure in
the  house, you pull that quickly in by flow."
     "You can characterize the undisturbed ground with respect to radon
availability being a product of radon concentration times the mean migration
distance, by whatever transport mechanism.  Does that tell the whole  story
or do  you have a two-part problem, one of getting the radon to the subslab
reservoir, and the second of getting it into the house?  By assessing the
first, do you get a handle  on the whole picture, or not?  In time the
Berkeley people will give us the coupling coefficients."
C(M.M.)  "I think the variability we're seeing between soil gas  levels and
indoor levels definitely says that the second process may be a major
C(R.S.)  "As Brad pointed out in his discussion this morning, it is a
coupled problem.  You've got the impedance across the building shell,  and
the  impedance of the soil.  That means that just knowing where the radon  is
high in the soil is not enough; we have to know at which points  the radon
can  gain entry into the building."
Q(K.G.)  "What about some of the soils we tend to find in this area which


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
tend to be heavy clay and wet?  You can pull a vacuum with a hand pump when
trying to take a gas sample... as a matter of fact, if you take repeated
samples, you can see the radon concentration go down as you deplete the
source.  How do you measure the soil gas concentration there?"
A(A.T.)  "If that, in fact, is the location of the radon source, then you
don't have a problem."
C(K.G.)  "What do you mean we don't have a problem   elevated radon levels
are present?"
C(R.S.)  "Alan's point earlier was that if you have a diffusively driven
reservoir, the house pumps on it in a diurnal cycle reflecting the fact that
the indoor-outdoor pressure difference flows a diurnal cycle.  We see that
the reservoir may be depleted in one part of a day and replenish itself in
another.  This may explain what's going on near houses where the soil is of
low permeability but where there is a reservoir under the soil."
Q(A.C.)  "Do you see a diurnal change in the level of the reservoir?"
A(B.T.)  "We haven't see it yet."
C(  )  "But in one slide you showed in Philadelphia did show a time-varying
soil level."
C(R.S)  "But the frequencies didn't match."
C(A.C.)  "Well, then your facts don't match your hypothesis.  I'm not saying
that was the situation at that particular house but rather that it is a
plausible explanation for some house situations."
C(T.B.)  "The problem is that you've sampled using a small hole about a
meter deep.  I might come in and excavate all that impermeable red clay off
the top, and discover that four feet down is a layer of shattered shale
which you've missed.  We don't have x-ray eyes; soils aren't uniform and
isotropic.  All our models are uniform and isotropic, but if you were to
make a finite difference model, I could imagine many soil configurations
that could give you some very anomalous results.  I see that occurring time
after time."
Q(AC)  "Have you considered going through the slab and measuring soil
permeability below the slab?
A(K.G.)  "Yes, on that house we did just that, and there was no permeability
under the slab."
C(T.T.)  "The way I've accomplished that over the years is simple, but
requires a back-hoe.  I just dig an eight foot trench, get down in the
bottom of it, and I take a flux measurement through the bottom of the
trench.  The soil gas doesn't tell me anything.  I've mapped it, I've tried
to correlate it with indoor concentrations.  I've used pipes to measure it
at various depths in the same hole.  I really question whether these soil
measurements are getting us anywhere."
Q(M.M.)  "Let me see whether I can put this in a final question then.  Do we
fee-l that soil gas measurements are a useful, viable and cost-efficient tool
for diagnosing radon at a site?"
Q(A.S.)  "What is the question which soil measurements are  answering?"
A(W.L.)  "Radon availability."
C(A.S.)  "That's more than soil gas then?
A(A.T.)  "Yes.  I think a soil gas measurement per se can tell you something


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
only if it's very low or very high.  But without the permeability data the
procedure is highly questionable."
Q(W.L.)  "This is where the question of nomenclature comes in.  In
Montgomery we agreed that the product of two factors defined the entry rate.
They are radon availability and transport efficiency.  Transport efficiency
itself is a function of soil permeability, pressure differentials, and so
Q(T.B.)  "But how could we discover irregularities in the composition of the
soil, for example, pockets of sand, using soil measurements?

C(another person)  "Don't forget that the ratio of surface area to volume
for clay is very large, so it gives very high emanation efficiency for the
radon.  The transport efficiency is clearly very poor, but put the clay next
to a layer of sand, and you can get the transport."
C(W.L.)  "The soil gas measurement is very close in my mind to the radon
availability.  But without these other factors the situation is still very
C(A.T.)  "Wait a minute -- I don't believe we've agreed that radon
availability is the value of the radon concentration in the soil -gas.  When
I say  "radon availability" I'm very definitely including the soil
permeability, the diffusive and advective flow, in addition to the radon
concentration in the pore space."
Q(R.S.)  "How then do you factor in the radon migration?  How would you
handle your definitions for a house which is pumping radon from the soil?"
A(A.T.)  "I define it as radon concentration in the pore gas times the mean
migration distance, which incorporates both the diffusive and the advective
flow.  The computation of that may be subject to change.  The concentration
of Radon alone is not a sufficient criteria."
C(E.K.)  "I'd like to go back to the charcoal.  When we developed the
charcoal method in New York, we meant it to be used indoors, at comfortable
temperatures.  Using it outdoors raises a series of new questions."
C(M.M.)  "I'd like to sum up by noting that we're not certain how useful
soil measurements are at predicting radon problems at a given site.  I
think, though, we are in general agreement that the most effective
measurement of soil gas is the direct measurement, and that we need to know
the permeability of the soil. "
Q(   ) "What is the progress that we are making on soil gas sampling?"
A(A.T.)  "I think I can answer that question and the one that Mike Koontz
raised when he asked whether soil  gas sampling was a viable technique
evaluating radon problems on for a single lot.  I think a good deal of
progress has been made.  A lot of measurements have been made, and I don't
think  there had been a lot of measurements before last summer...well,
certainly there have been some, but there have been a lot more since.  New
York State ERDA(?) has done a lot  of them, Jay Davis has done a  lot, LBL did
a  lot  last summer.  I do not think it's going to be viable on a  single lot
basis,  because in any given area  you have to develope confidence  that
you're getting statistical validity in your measrements.  You can't afford
to make too many measurements on a single lot before it gets  less  expensive


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
to build the house the right way in the first place.  But if you're talking
about a development that mayt encompass a couple hundred houses and some
acres of land, and you can afford to grid and spend several days doing it,
there may  (or may not) be a viable technique there.  I don't think we have
enough information at the present time to prove that.  It will take a full
year or so of gathering data to indicate the variability of a set protocol,
whosever it might turn out to be.  We have some indication that the results
are going  to be highly variable on a single lot.  If we saw the same
variation  that Brad a Terry were talking about as a general rule, I don't
think it would be a viable technique."
Q(H.T.)  "What is the mean migration distance you've been talking about?
A(A.T.)  "It's the distance which radon moves, by any transport process or
combination of them, in it's mean life, which is 5.52 days.  If you will
look in either Clement's thesis, or in Sherry et al. in 1984, 'Factors
affecting  Radon Transport in Sandy Clay Loam' in Journal of Geophysical
Research   (the published 1974(?) JJR(?) article doesn't contain the
equation), you'll see that the J, the exhalation Current Density under
steady-state conditions is equal to gamma times the square root of the
diffusion  coefficient times the porosity times the decay constant.  Gamma is
equal to beta plus beta squared plus one.  Beta is V over 2 times the square
root of D  epsilon Lambda.  It's a mess!  Multiply that by 5.52 days and
you've got it."
Q(D.H.)  "I'd like to step back again.  The first talk with Mike was a very
general survey over a land area, looking to see whether it showed signs of
having problems.  Then we went into very a very detailed analysis of the
many different ways we could sample radon in the ground, and then we came
back to the conclusion that a direct measurement (for instance, a grab
sample out of a hole) was the best way of getting local information.  Now I
think that you've just stated that you would be afraid to use that technique
for a given building-size plot, but that for a larger plot you could.  Are
we back to the simple surveys where we started out?  We started in the big
picture, and then we took this very detailed method and showed all of the
things which Terry was pointing out, with different types of sand and
everything else.  But we ran into trouble in the small picture, and we're
back using this very detailed measurement, but on a larger scale.  Aren't we
competing  now with much simpler methods?"
A(A.T.)  "Well, No.  When you're talking about the  gamma survey or the use
of the NURE data or regional type information, when you're talking about
square miles and larger areas,  all you're going to do is to predict that
most of the houses are going to be fairly low or else threatened enough that
one should use radon-resistant construction methods.  You can't make
predictions about what the radon will be in any individual house.  When you
start talking about sampling on a given lot, then you're trying to be
specific about whether or not you're going to have  a radon problem at a
house on the site.  You can't evaluate that possibility at all by taking  a
simple measurement of radon in the upper foot of the soil."
C(D.H.)  "You sound leary of making measurements down at that  small  scale."
A(A.T.)  "I'm not so leary of it, I just think  that you may have  to  make  so


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
many measurements that the costs of testing can increase above $2000, which
is already more expensive than most estimates I've heard for making a house
C(M.M.)  "The National Association of Home Builders says that builders can
build radon prevention into a house for $300 to $400."
Q(M.M.)  "We can return to this topic later, but for now we'll have to move
on.  We've talked about identifying soil gasses and measuring levels in the
soil; now let's discuss how we can identify a problem house?   Not a survey
of a given area or a specific, measurement for a lot, but rather, how can we
identify already constructed houses that -may have; problems?  I'd like to
narrow this to screening techniques for now, and we ca-n move to techniques
for measuring radon in specific zones of houses a little later.  Does any
one have any comments on surveys to aid in identifying of hot spots?"
Q(R.S.)  " Mike, doesn't it depend a lot on what level ytK3/re operating?  I
think that as Alan Tanner indicated earlier, if you have information such as
NURE or other radiometric surveys,  soil permeability information and other
things, you might be able to locate areas where you would do more detailed
surveys.  I think it's fair to say that we're not there yet in terms of
compiling all that information and putting it together in a way that you
could, with some assurance, say that a given area has a problem and that one
does not."
C(   )  "But we've done it."
C(A.C.)  "Yes, I also disagree with you, absolutely.  I've taken the twenty-
eight hundred readings in Maryland [that University of Pittsburgh has from
Maryland], and I can tell you exactly which counties or parts of counties
have a problem, and which ones .do not."
C(R.S.)  "But that's an ex post facto.™
C(A.C.)  "That's right.  Now as far as I'm concerned, tbe people who are
using the NURE data and who think that it's a great technique, when they are
confronted with hot spots that we've found using other techniques, they have
confirmed that they should have seen them, but they didn't."
C(   )  "That's not entirely true."
C(A.C.)  "They all come back and say, Hey!  Clinton shows on the NURE map,
but  nobody mentioned it."
C(   )  "But nobody looked for it before.  The reason why the geologists
haven't been able to find the hot areas is that they haven't looked for
C(A.C.)  "I'll tell you the £aae thing which I told a. geologist  last week.
There are twenty to twenty-five spots in the Reading Prong area  of New
Jersey, where the geologists who identified the Clinton Knowles  area  in  1971
as a good place to mine uranium.  In that part of New Jersy there are twenty
to twenty-five hot spots that he was on personally  in 1971 which were as
high in uranium content as Clinton Knolles, and every one of those should be
as much a hot spot as Clinton Knolles, but no one has found them yet."
C(R.S.)  "I didn't actually mean to get us started  on this.  I  thought what
that meant was the sort of survey information which the states  generally
have, and it's a one- or two-page document describing the kinds  of houses,
where they're located, and that in fact may relate  to geological maps and


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
other information.  But housing characteristics, occupancy characteristics
gives you some idea of the level of concern we should have about the houses
in this area.  Is that a valid set of survey information?  It's readily
available for most states, and part of existing programs.  How much of that
do we as people interested in finding problem houses and fixing them should
we try to solicit?  Another source of readily available information is
University of Pittsburgh Data."
A(R.S.)  "What I was starting to answer earlier was the question of what
sort of screening surveys we should do first.  Is that what you were
Q(M.M.)  "Let me rephrase the question.  I was specifically talking about
the screening survey.  Given the fact that we have some information, whether
geological or NURE or whatever, that would focus us on some area in a given
state, what is the next step in identifying radon problems in given houses
or groups of houses in this area?  I'm talking about specific surveys,
making indoor measurements.  These are the data that Chuck would later used,
and it's been generated in a random way, Bernie Cohen's data."
C(R.S.)  "One of the things which you've started to do, a step in the right
direction, is to wintertime charcoal screening surveys.  They don't tell you
anything about the annual exposure, but it could tell you something about
hot spots which you can then correlate with external information."
A(A.C.)  "In looking at .16 states, at least 12 out of 16 states had at least
one county with at least 50% -of the houses above 4 pCi/L.  If I lived in a
county in which 50% of the houses measured above 4 pCi/L, I would certainly
have my house tested, and every house in that county should be tested, there
is no other way to tell the extent of the problem."
C(R.S.)  "That's right, I think you could use that as a gross screening
survey, that someone would have to follow up."
A(A.C.)  "The ten-state survey being done right now by ORP for the 2000
cannisters being run followed by 1000 follow-ups is going to really tell you
whether those ten states have a problem and in which parts."
C(R.S.)  "But it's very important to do it in the wintertime."
C(T.P.)  "I'd like to say something about the surveys which ORP is working
on.  We're just now getting some of the results back from the state surveys,
and we have only preliminary results.  I'm not  exactly sure how accurate
they are.  Using geological characterization, at least for Tennesee, we've
been able to find geometric means higher in the areas predicted to be high.
C(M.M.)  "So the state survey data may correlate with  the areas predicted  to
be high.   To be sure that this type of data is comparable, we need to
standardize, to focus on standard measurements made in these houses.  I'm
not sure whether it has to be in the winter.  It's true  that doing  it in the
winter will give better closed-house conditions, but if  you can achieve
closed-house conditions, and if you can measure on lowest global  levels,
then you tend to maximize the values you find for a screening purpose,  and
your data will be pretty good."
C(G.F.)  "Just a remark back to Chick's comment, I think New Jersey's
approach in their follow-up, looking for another cluster situation  like  in
Clinton, is mainly their fan-out program, when  they have a discovery home  or


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
an index house of 200 pCi/L.  It's an excellant approach to find those
pockets around the state that indeed have elevated homes in the vicinity.  I
don't know if Pennsylvania is doing that or other states you are in touch
with, but even though it costs a lot of money, it's to find the pattern of
high-level homes in a given territory."
C(A.C.)  "Of the counties where I'm saying that 50% of the houses are above
4 pCi/L, most of them do not have any house with levels above 100 pCi/1.
But the number of houses in the range 20-50 pCi/1 are far higher than
C(T.P.)  "When you do look at that data,  you can bring that back to the
geology of the area.  I'm not saying that this could apply to a specific
house, but suppose you look at a number of homes on black shale which is
elevated, or suppose you look at a large number of homes which are elevated,
and you examine the geology and the other information, you can use that to
go and find other high levels."
C(G.F.)  "We're sitting right here on a Triasic Ridge, and there was no
comment made by state geologists a year and a half ago that this was at all
a probable area for radon.  So, I disagree with you on that."
C(T.P.)  "The EPA has a national radon map.  I've been looking at the data
that goes with these maps, and the triasic basins are responsible for
elevated levels, black shales are responsible for elevated levels, so I
think we have to look into some of the other areas. "
C(M.M.)  "If we could stay off geology for a few minutes here.  Gene was
talking about fanning out around high areas once you've discovered them, and
making additional measurements.  That seems to be a good policy.  Chick was
talking about taking measurements in every house in the United States.  That
would tell us all we need to know." (laughter)
C(A.C.)  "You've misquoted me."
C(R.So.)  "We need to get the permeability better documented.  This variable
is jumping out at everybody, but there's almost no discussion of the
methodology and protocols needed to pin down this variable.  We should
always have two parameters for each house.  We keep describing a situation
in which only one of two parameters is known, the other one is guessed, and
the explanatory power is very low.  People have been aimed too much at
measuring radon concentrations."
A(A.T.)  "It isn't that we don't understand it, we just haven't measured it.
First of all, there is a data base, though it isn't all that we would like.
 Most counties in the U.S. have data concerning perk tests and soils
information, or the Soil Conservation Service has information.  The Berkeley
group spent a long time studying soil groups and which ones had tendencies
to be permeable.  There exist very specific data, sometimes with very high
density, on things like perk tests.  They may not be quite what you want,
but.they do give you a strong clue.  In the state survey effort that Tom has
been talking about, those data are used as clues in classifying counties as
high or as low risk.  So far it looks as if it's working pretty well."
C(R.So.)  "Fairly well" is the last word there.  How much stronger is the
explanatory power of geological measurement when you have these two
variables instead of just one?  We should be able to get a quantitative  feel


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
for how much we can improve our explanatory power when we consider both of
these variables instead of just one."
A(B.T.)  "We do that under the slab.  You take your grab measurement, we see
how pressure fields develope, and you're basically measuring permeability."
C(R.So.)  "The goal would be to improve the quantitativeness of these
methods.  The discussion in these last two hours has been non-
quantitative ."
A(A.T.)  "The really missing variable, though, is where you are on the
coupling efficiency between the ground and the house."
C(R.So.)  "The third element is obviously how leaky is the house boundary?"
C(A.T.)  "We're going to come to a solution to the first two before we
figure out the third, I'm afraid."
C(D.S.)  "Rich suggested that you needed winter and summer readings, some
indication of an annual kind of situation.  In looking at the Canadian
survey, they only do summer measurements.  They've come up with very low
levels of geometric means.  They have no problem, by their definition.  In
my opinion it is inadequate to make measurements in only one season".
C(A.C.)  "In fact the highest level ever measured was found in June, closed
house, on a dining room table, when temperatures were in the eighties and
nineties, slab on grade house, a value well above 5000 pCi/L.  The
measurement in the wintertime was only 2000 pCi/L.
C(A.T.)  "That soil runs several hundred ppm of uranium as well."
C(A.C.)  "In fact the gamma measurements in the backyard got as high as 120,
average at the four corners was about 80."
C.(T.T.)  "I don't think we should overlook the value of gamma in a quick
screening method either, I mean an on-foot micro-R-meter kind of survey.  If
you've got high soil gas you're going to see the bismuth gamma, you're going
to see elevated background in a hot spot.  If you've got gamma in any
amount, you can bet that you'll find high radon in that area."
C(M.K.)  "But if you have low gamma, you still can't tell that you don't
have a problem."
C(T.T.)  "Yes, but it will tell you right away where your real hot spots
are.  I've never seen an extremely hot house that didn't have a significant
gamma radiation level associated with it.  I came out of the Watras's house
in my sport coat, and about 30 minutes later down in the valley I measured
about 60 micro-R per hour, background was twelve to fifteen.  It's a good
quick screening tool to find the hot spots."
C(M.M.)  "I've seen a fair amount of correlation between gamma and radon
levels,  and the correlation is better at high levels.  The gamma seems to
indicate the high level houses a lot better.  Gamma seems to me like a
useful tool for identifying those very high level houses.  It may not be as
useful for those houses which range in the 10, 20 or 50 pCi/L levels."
C(A.S.)  "No, I would say that it is the other way around.  Gamma may be
useful for identifying regions, but as for identifying individual places
(unless they are contaminated) it is not very useful."
Q(M.M.)  "You're saying that gamma could grossly  identify a region,  but
probably would not identify a single house?"
A(A.S.)  "Yes, particularly when we're dealing with these very high  houses.


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
Let me say that it seems insufficiently predictive for me to suggest it as a
general rule."
C(T.T.)  "Let me use an example to help me with my argument.  We've got an
area in Edgemont, South Dakota, where none of the houses exceed 30 pCi/L
radon concentration.  This was not the result of any mill tailings, but
rather, occurred naturally on the ridge where the houses are located.  The
gamma is consistently 40% above normal background down along .the streak
where we've  got these elevated houses.  We're seeing the radon and the
Bismuth 214  in the soil gas in an equilibrium."
C(M.M.)  "So here the gamma is identifying even lower-level houses."
C(  )  "The  question has to be phrased very carefully here:  are we looking
for something to tell us not to put radon resistance into construction?  Or
are we looking for something to tell us to be on our guard for extreme
problems after the fact?  I see no evidence [that we've found] an.indicator
that says that one should not put in the radon-resistant construction.  Yet
we see many  indicators here that tell us that we may be risking a very high
house, and that we should be on our guard."
C(A.T.)  "Let's take south New Jersey.  It's in the Atlantic coastal plain,
there are rather few places where it would be reasonable to expect that
there would  be course material to give you a permeability problem.  The
uranium series activity in the ground is quite low.  You might want to say,
'Look out, boys, look out for some ridges of gravel that we might find
sometimes; there you've got to take caution.' But otherwise this is an area
where radon-resistant construction should not be necessary 99% of the time.
The same thing goes for much of the outer coastal plain on the east coast.
You get down to the Carolinas, then you've got to start worrying about
Thoron.  Unfortunately, the measurements being taken now do not detect
Thoron--not  that they can't, but routinely they try to exclude Thoron from
consideration.  I think that is going to be a mistake in some places."
C(T.B.)  "If you get Thoron present in any large amount, you'll get a
background which will last longer, and I haven't seen that any place.  "
C(A.T.)  "Well, so far I haven't seen Thoron greater than 30% of the radon.
count.  But  there are some places where it may occur, there  they're known.
C(M.M.)  "Let's move on now to visual inspection and questionnaires, out of
the realm of source availability and into the realm of diagnostics.  Visual
inspection and questionnaires:  what information can we gain by simply
looking at the house and asking the home-owner questions about the house?
That will give us information which we'll later use in developing mitigation
C(A.C.)  "The LBL questionnaire which we were using both in New Jersey and
in other places consisted of  five or six pages of questions.  The  surveys
simply give  us a systematic way of looking at the most likely entry points
for.radon.   Mary Cahill has made a few house visits with me, and  I've walked
through a house, spent a half hour in the basement, gone upstairs  and sat
down at the  dining  room table, and she was writing and I was helping.   I  can
answer 90% of the questions there without going and looking.  The  reason  is
that I've been in enough houses and I've found enough cases where  there are
obvious radon entry points that I know what  to look for.  The best  thing


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
you've got is your pair of eyes.  You often run into things that you had no
way of predicting.  We were walking through one house in New York when I saw
a block of wood lying on the floor.  I kicked it and it didn't move.  When I
picked it up I saw that it covered a hole in the slab.  This was on an
asphalt tile floor, and the block of wood covered a cleanout plug for a
sewer line that went out to a septic system.  The plug had never even been
caulked in, and the soil was showing.  There was no way to look for this
sort of thing, it just happened to be there lying under a piece of wood.
You can see holes in the wall without any problem.  As Terry said this
morning, if you can see dirt, you know you've got the potential for a
problem.  But you've got to constantly be thinking of places where dirt
might be exposed, that you can't find.  Arthur can tell you stories of floor
drains which looked absolutely innocuous, not at all like they could be
entry points for radon.  After about a week of trying to find where that
last fifty picocuries of radon was coming from, he tested the floor drain,
and it was the floor drain without a trap, but drained to the surface behind
the house, not connected in any way to an entry route.  However, when he
finally took his grab sample out of the floor drain that didn't have a trap,
and measured the velocity of flow in it, there was enough radon in the gas
coming out of the pipe to account for the level in the basement.  There was
a perforated drain tile all the way around the footer, and where that drain
surface ran through or under the footer, they tied the drain tile into that
line, and ran it to the surface. That was a good collection system around
the house, the soil gas was coming up an innocuous line which had no
perforations in it.  Because of the drain tile arrangement it was dumping
radon into the basement.  It suddenly dawned on me a month ago that when I
built my own house, I ran my three basement drains to daylight, and one of
the three has never had any water in it.  When I went out under the
foundation with it, I remembered that I tied my footer drains from all
around the house to that same kind of line, exactly what I'd seen in
Pennsylvania.  There's a source you have to look hard for; there's no way to
know what is there.  Even if someone had questioned me, I wouldn't have
noted it, because I wouldn't have thought of it.  In fact, it didn't even
occur to me until a year after our visit to Pennsylvania."
C(A.S.)  "Let me add to that.  One home-owner told us there was no weeping
tile drain around the house.  I suspect he may merely have had crushed stone
C(A.C.)  "Either way.  There's some way that soil gas is getting in to that
pipe and coming in.  It used to be very common to put drain tile around the
house, go in through the basement, and into the sewer line above the trap.
Then they made it illegal to put storm water in with sanitary water.  When
you're looking at these houses, think of yourself as a gas, and look for any
holes you might get through.
Q(M.M.)  "In talking with homeowners and making visual inspections, what
additional information could you gain for designing mitigation techniques
for that house?"
C(A.C.)  "As far as I'm concerned, the longer the questionnaire, the better.
(laughter)  This may come as somewhat of a surprise to your people, Mike,


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
but I'd like to get that questionnaire down to two pages.  The reason is
that I'll pick up most of these things, [that home-owners write on their
questionnaires] when I go through a house.  But we have to think about the
new people just getting into the field, not just the experienced people
who've been through hundreds of houses."
Q(D.S.)  "To put this in context, are you talking about a twenty- or thirty-
minute walk-through, or about something which has been categorized as coming
later, as part of the pre-mitigation surveys?  At that point you need six-
or eight-page questionnaire, you need all the information down in a
systematic form."
A(M.M.)  "I'm talking about a very cursory, preliminary visual observation
of the house, and questions that might be asked of the home-owner."
C(D.S.)  "That's the sort of thing that states often do.  When they think
they've got a problem, they'll visit the home and fill out a one- or two-
page questionnaire.  But that has limited value."
Q(T.B.)  "Is this a questionnaire that someone takes out and walks around
with, or one like those which Bernie Cohen sends out?"
A(M.M.)  "This is a questionnaire like those which Bernie Cohen or the state
might send out.  We're not  into pre-mitigation diagnostics yet."
A(A.C.)  "These one- to two-page questionnaires have got to be so simple and
explicit that even a home-owner who knows nothing about construction could
understand it.  You've got  to assume that he knows the difference between a
public sewer and a septic system, and  that he knows whether he's on public
water or a well.  These things are important in this first phase:  whether
his house has a' crawl space, slab-on-grade, or basement, or some combination
of these;  if he has a basement, whether  it's block-wall or poured concrete.
These questions have to be  phrased so  that the average homeowner, who knows
nothing about house construction, will know what the question means and how
to answer it."
Q(   )  "What is the value of this type of questionnaire?"
A(A.C.)  "When we're going  to do an additional research project in an area,
and we want to cover 20 to  30 houses,  then we'd like to have 100 to 200
houses at the beginning to  start sorting  from.  If we start out with 500 or
so,  then we can sort those  into categories based on their substructures, or
into other categories, so that we can  aggregate like houses into study
groupings.  However, such a questionnaire does not help  in the general
mitigation effort.
C(   )  "The point I was going to make  is  that the way houses are built no
two  exactly alike, if the soil gas is  the same underneath, it really doesn't
do you much good just to know the substructure of a house as far as  telling
you whether you're going to have a radon problem.  You've got to measure
anyway.  At that point you've got to do a longer questionnnaire, of the type
done before mitigation."
C(M.M.)  "So the information which is  to be gained here  is simply the type
house, slab-on-grade vs. crawl space or basement, and questions as simple as
the  type of walls, i.e., concrete block vs. poured concrete."
C(A.C.)  "What kind of sewer, what kind of water,  type  of fuel, type of air
circulation, which might tell you something about depressurization of the


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
Q(K.G.)  "Isn't this the same idea that mitigators are already using when
they prequalify a house by asking a list of about 10 questions over the
telephone?  This method has already been in use for several years."
C(T.T.)  "There are about 10 key questions which really mean something to a
mitigator.  I have an example here, a letter from a man in Silver Spring,
Maryland.  I fixed his house 3500 miles away and asked him 10 questions.  He
wrote me a thank-you letter saying "I got [the radon] down from 16.8 pCi/L
to 2.8 pCi/L, Thank you Mr. Tappan."
A(A.C.)  "I did the same thing with someone in the western suburbs of
Chigago,  who had 10 pCi/L in his house in October.  He did nothing but seal
the basement.  He called me back in January with 1.7 pCi/L."
C(M.M.)  "We'll try to put those ten questions together and offer them as
information to the group.  One final question: It's a reflective question.
When we're talking about a questionnaire, we have to be sure what its
purpose is.  I think we've been discussing several different ones
simultaneously.  The purpose of that ten-question questionnaire is to
determine whether there is any action which the home-owner can take, short
of calling in professional diagnosticians or a mitigation team.  There are
five or six questions which you can identify, so you know if there is
anything the homeowner can try.  Once we get beyond that questionnaire, the
questionnaire in the next level is much shorter.  If the home-owner has
confirmed the measurements, or has tried sealant  (which is generally what
we're talking about here), the next questionnaire simply askes the name,
address, phone number, and the date on which they are available.  Any other
questions are really placebos, to show that you know your stuff and are
concerned about their house."
Q(M.M.)  "This leads us to] the determination of radon concentrations in
different zones of the house.... Another thing I'd like to touch on is  the
status of our scientific knowledge, our need for additional research:   do we
feel we've reached a point where we can define the topics we've discussed
this morning?  I'll let Wayne open that one up."
C(W.L.)  "Let me pose one question for thought over coffee break.  I come
from a side of DOE which has been concerned with basic research.  Until  this
morning I was thinking that we were going to have to do some detailed
geological studies to develop better predictive models on a regional basis,
to try to understand why certain mitigation techniques are effective; to
understand all the factors which determine radon entry rate, so that we
really have a firm scientific basis for making generalizations from the
experience we gain in the field.  However, the message I've gotten today  is
a little bit of a surprise to me.  What I seem to be hearing is the fact
that we have already developed the kind of qualitative understanding we need
to be effective mitigators on a very broad basis, even though we can't  put
all the factors important in defining radon entry together into a coherent
equation.  I was very impressed by the success one speaker had, based on  a
very limited approach to the problem.  If that is true generally, then
perhaps there are just a very few questions on which we should focus our
attention.  That is, perhaps we need not develop a radically more detailed


Radon Diagnostics Workshop, 1987.  Phase 1 Discussion.
scientific understanding.  Perhaps we are already where we should be."
C(A.T.)  "There are 79 million more houses, aren't there?"  (laughter)
Q(L.K.)  "One thing which we haven't discussed, which affects your panel and
the panel on post-mitigation diagnostics:  how well we can relate a
measurement which we do either before or after the mitigation to the annual
average?  This has certainly been one of the concerns in the houses in
Clinton, and when you get a year's worth of data those houses are probably
going to be under 4 pCi/L in an annual average.  They're not below 4 now so
you can't really say that they are successful.  I think that one has to be
careful that annual average exposure is really the number, and not the
single measurement in the basement."
C(T.T.)  "We have tried passive mitigation systems.  In one case the levels
stayed low to December when we hit a spike and we put fans in the exaust
stacks.  We probably overreacted and we would have been o.k. on an annual
C(M.M.)  "So we realize that we need additional information.   There are
studies going on right now to help us translate fairly short-term
measuremtns made under different conditions and at different times of the
year to that annual average.  Our goal is to keep the annual average below
some given number."
C(L.K.)  "So the groups who mitigate in the summer must know how low they
have to get [the radon levels] so that it will stand up in the winter [for
the yearly average].  When you're mitigating in the winter, you don't
necessarily have to constantly stay below 4 [pCi/L].
C(R.S.)  "But it's the real-estate market which is driving a lot of
C(L.K.)  "But if we have the data to back it up, to show that those numbers
mean something... We can't tell them anything now based on one measurement,
without an annual average."
C(  ) "If you hire me to do a mitigation job, and if I bring it down from
200 to 8 PCi/L, and if your house is on the market, is that going to satisfy
you? "
C(A.C.)  "They won't sell the house."
C(  )  That's right, and 65 to 70 percent of the mitigation in this state
being driven that way.  It's very difficult to get that point about the
annual average across to the home-owner, especially when dollars and cents
are involved."
C(M.M.)  "Those are the facts of the real-estate market, and I've had to
deal with it too.  Thank you all, that ends this session."

Radon Diagnostics Workshop, 1987.  Phase II

            PRE-MITIGATION DIAGNOSTICS -  L.  M.  Hubbard,  Chairman

  C(L.H.)   "First I would  like to go  over the order of the topics and the
  distinctions we will make between research and "real world" applications of
  diagnostics.  Questions  submitted ask what are the answers we are getting
  from the measurements we have been  making over the past few years?
  Availability of the equipment; how  easy is it to implement; and what are the
  costs involved are some  of the other questions.  A good example of how
  research  approaches can  be applied  in the field was given by David Saum
  earlier in the workshop  -- looking  at subslab ventilation diagnostics.  In
  what percentage of homes will SSV work successfully is another question to
  be answered.  Questions  about some  of the most useful diagnostics, grab
  samples,  both ambient and depressurized with a blower door, are often asked.
  Communication under the  slab is a question that has already received
  considerable attention  so perhaps it doesn't need much more discussion here.
  Tracer gas measurements, differential'pressure measurements,  soil gas flux
  measurements are  all topics needing discussion.  One question that has been
  asked is  how can  stack  pressure be  measured  -- hopefully we will have time
  to discuss that question.  Are diagnostics cost effective?  I would like to
  hear from the mitigators on that question.  Also, do the seasonal variations
  matter?   I would  like to begin with a  few words from Wayne Lowder on
  research  versus the  "real world" diagnostics."
  C(W.L.)   "First of all  I have been  chastized by all the DOE contractors
  during the intermission for my remarks.   However, my statement was just to
  stimulate discussion.  (Laughter) There is a very important distinction to be
  made concerning the  real world application of our current state of knowledge
  which derives from the  research over the  past few years.  What I am hearing
  today is  that this research has been very successful in pointing out  the
  significant  parameters:  what should we be looking at and how  we can simplify
  the diagnostics for  real world applications.  As we assemble  many case
  studies of success, mitigating under some degree of ignorance, we need a
  scientific knowledge base  in order  to  understand why we are successful in
  particular cases.  In this way we can, with  some degree of confidence, move
  on to improved procedures  for  a variety  of circumstances.  There is clearly
  a need for research, the EPA field  demonstration program is a prime example,
  especially the study in New Jersey, which is a combination of the practical
  and the research  aspect* of mitigation and diagnostics.  This is a very
  important effort.
       I would like to stimulate the  mitigators here to probe the questions  --
   do you feel confident  that you will continue to be successful and what do
  you think are the needs for better  information from the scientific
  Q(L.H.)  " What diagnostics are useful  to  understand the radon mechanisms?"
  A(W.L.)   "We are  really zeroing in  on  those  factors in  the environment  that
  are'relevant to radon entry rates in housing.  The question of radon  in  soil
  gas is extremely  important, since it surrounds the house,  and supplied  the
  "available radon".   Its the soil gas that transports  the radon into our
  houses and is the source for the indoor  exposure.  Permeability  is  the
  property  of  the soil that  tells us, together with  the differential  pressure,


Radon Diagnostics Workshop, 1987.  Phase II

  the rate of soil gas transport.  Maybe in a way we ought to define an
  idealized situation which will represent a figure of merit - a model house
  (or several houses) with properties that are well defined so that when you
  have a pressure difference across the envelope and you have certain defined
  soil characteristics and a level of radon in the soil gas, you have now
  defined the "source term" in this idealized situation.  Whatever number you
  get is representative of a particular site even though it doesn't represent
  a real house, it does relate to the idealized set of circumstances.  The
  real problem is there are so many variables, particularly within the house
  itself, you clearly can't develop a model (with a finite number of
  measurements at the site) that will define the radon entry rate at any
  particular time.  So really it comes down to the fact that we have to
  understand the mechanisms involved and generalize from a particular case."
  C(L.H.)  "Let's hear from the mitigators".
  C(R.Si)  "What I have been hearing is that SSV achieves a high degree of
  success but that it is highly dependent on the conditions under the slab.
  What we are then dealing with is a very small percentage of houses where SSV
  doesn't work because of  soil conditions.  We are looking for an amount of
  suction that is going to overcome the radon flow into the house and redirect
  that gas flow.  Some of  the things we want to look at are the necessary
  forces to just what is necessary to remove the radon.  Another item would be
  aimed at house without good communication under the slab where using a
  "small well", you might  short-circuit the radon before it reaches the slab.
  Q(L.H.)  "What percentage of houses are not cured using SSV?"
  A(R.Si.)  "The percentage we have found is very small, i.e., only one or two
  houses out of a hundred.  Even then it is often a question of fine tuning.
  Using dampers in the mitigation piping allows one to increase the suction
  where it is most needed.  For example, with slab-on-grade it might not need
  as much subslab ventilation because of settlement in the area along the
  common wall."
  Q(L.H.)  "Do you use premitigation diagnostics?"
  A(R.Si.) "The premitigation diagnostics are limited to a communications
  test, taking into account all  the obvious things that have to be dealt with,
  working toward a mitigation strategy.  In the case of limited soil porosity
  we would employ a collection pit area, something we have done for the
  Piedmont study.  The number of pits would be related to the basement
  geometry and soil porosity."
  Q(A.C.)  "How big is the pit?"
  A(R.Si)  "Typically its  a two foot cube, but we may include perforated walls
  and base to  increase the effective volume to help draw in the radon gas."
  Q(L.H.)  "Bill, how much premitigation diagnostics are you using?"
  A(W.B.)  "Often it is just a walk through where we anticipate porous soils.
  In the early days, we would have used an air-to-air heat exchanger for radon
  mitigation but now that has become a less attractive option, as we now are
  removing those units and replacing them with subslab units."
  Q(L'.H.)  "Do you use grab samples in your work?"
  A(W.B.)  "I  do use grab  samples occasionally to test for hot spots.  If
  there is a question of communication under the slab I do use the vacuum
  test.  That's really the most  important test where I use the Magnehelic
  gauge to get actual pressures.  Using smoke, sometimes it will not go down


Radon Diagnostics Workshop, 1987.  Phase II

  the hole even when you can get a gauge reading (sometimes after 15 to 30
  seconds) with marginal communication.  At other times the opposite is true,
  so you should use both methods."
  C(A.S.)  "Let me comment on the word "diagnostics".  It is being used
  currently as being all things to all people.  If we follow the medical
  theme, we know what disease these houses are suffereing from, it is
  "radonitis".  It is "diagnosed" by making one measurement to show radon
  levels are elevated.  The subsequent investigation that takes place is
  "pathology".  We are looking at the approximate cause, but knowing the
  causes of a disease may provide no help in the treatment.  Our scientific
  friends are involved in "pathological research".   Mitigators are involved in
  "therapy planning".  There is a sharp distinction between knowing the
  pathology and determining what can be really helpful.  Subslab ventilation
  could be viewed as the penicillin of the radon world.  If we can achieve
  soil depressurization we know the problem will go away.  We don't need to
  know if people are running dryers or what the pressure deficit is in the
  C(W.L.)  "You don't even need to know where the hot spots are."
  C(A.S.)  "That's right.  You probably don't even have to know much about the
  C(R.Si.) "Probably the most time consuming item is how to get the exhaust
  pipe up to the roof."
  C(D.Sa)  "I agree with some of these statements, but its hard to say what
  percentage of the time you will get results by slapping something into the
  nearest convenient place.  Perhaps 50% of the time.  We certainly agree
  diagnostics aren't always absolutely necessary.  I would like to go back one
  step.  There seems to be some question what SSV is actually doing and what
  is its active mode that is actually solving the problem.  I claim that
  suction on these surfaces prevents radon from entering.  There seems to be
  some question if its the air movement that has something to do with this.  I
  claim that if we could do a perfect sealing job and no soil gas came in from
  the upper surface of the soil  that would be fine and that suction itself,
  with limited air flow, would be the goal".
  C(L.H.)  "I thougt the question was flow out of the mitigation system?"
  C(D.Sa)  "I don't think we have even really decided how radon comes into the
  house when good sealing is done.  I am finding it's pressure driven flow
  through concrete therefore all my actions are to get as low an airflow as
  possible and as high a suction as possible.  There are some people here that
  don't think that's right."
  Q(A.C.)  "We did have a little discussion during the break.  But first I
  would like to ask if there is  any significant passage of soil gas or radon
  through four inches of concrete, that has no cracks  in it?"
  A(D.Sa.)  "I have made such flux measurements.  Placing a box over what
  appeared to be crack-free concrete I noticed a build up of radon in the
  winter in the box, but in the  summer time, with no pressure differential,
  the' radon was not present."
  A(B.T.)  "In our flux measurements on concrete blocks and poured walls and
  floors, if you do the calculation, you can only account for a fwew percent
  of the indoor radon levels.  These measurements would account for diffusion
  and microconvection and it is not enought to account for the indoor levels


Radon Diagnostics Workshop, 1987.  Phase II

  that we see.   A fine network of cxracks may contribute to the problem but
  will not be sufficient."
  Q(D.Sa.)  "There is a bit of contradiction here - why can't we seal and
  achieve our goals?"
  A(T.B.)  "We are digressing into mitigation.  Knowing where it comes from is
  important.  My experience has been with doing subslab suction with one
  pressure point in the corner.  The experiment had other points open at the
  other sie of the slab, hoping to indues cross flow assuming that was
  important.  The more we sealed the better reductions in radon concentration
  we achieved.   Thus we moved to higher suction under the slab and less
       A second example is from one of the Clinton houses with a dirt floor
  crawlspace.  We placed perforated PVC pipe in a grid on the floor and sealed
  the floor with a heavy polyethylene film - a that is transparent to radon by
  diffusion.  Then we applied suction to the PVC pipe with complete success -
  the radon did not penetrate the plastic.
  General Discussion:   (T.T. D.Sa. R.S., T.B., etc.)  The goal is to reverse
  the pressure gradient, flow is not the important feature rather it is the
  fact that flow is from the substructure into the soil.  The establishment of
  a slight negative pressure is all that is needed.
  C(A.T.)   "NBS has been trying to develop a portable radon source using a
  thickness of polyethylene where half the radon decays prior to passage
  through the film  (13  to 16 mills).  Ron Colley and Robin Hutchinson are the
  people to contact."
  C(T.T.)   "We use radium ore inside a plastic covered bucket as a method for
  evaluating materials.  It's amazing how many plastic materials that radon
  moves  through."
  C(T.B.)   "Diagnostics reveal how good the communication is under the slab.
  The presence of a good gravel base or soil separated from the slab means
  that one  can often be successful with SSV using a single suction point even
  on  the basement perimeter.  In other cases, spotty suction is evidenced (in
  one direction  for example) and in clay there may be no influence beyond the
  suction point.  Powdered soils may indicate little communication using the
  vacuum cleaner technique yet frean may pass through them.  SSV systems thus
  may still prove successful.  At the fine end of the soil particle size
  range, basement walls may become more important as a radon source.  Freon is
  very slippery  and can move quickly through even fine soils with the suction
  in place."
  C(R.S.)    "One justification for further research is that all mitigators
  indicated they have installed  systems that don't work the first time."
  Q(L.H.)   "Where do blower doors play a diagnostic role?  The usefulness of
  blower doors relates  directly  to the application.  If SSV doesn't work, then
  the BD may have application to radon mitigation basement pressurization,
  heat recover ventilation, or subslab pressurization."
  A(R.Si)   "We used blower doors for subslab system evaluation but we have
  abandoned that approach.  The  question is where do you use the blower door?
  We have a high confidence that with one hour of diagnostics we can tell
  whether SSV systems will work, without use of  a blower door.  If SSV won't
  work,  then what is the next best mitigation method?  More direction on that
  point  may involve the blower door.  Heat recovery ventilators, basement


Radon Diagnostics Workshop, 1987.  Phase II

  pressurization, subslab pressurization are some of the candidates for the
  second best strategies."
  A(T.B.)  "The blower door is useful for sizing the fan for pressurizing the
  basement.  The fan must be small enough so that a large energy penalty won't
  be paid  (same range as normal air infiltration, i.e., less than 300 cfm).
  One also wants to avoid too much suction upstairs which can cause problems
  in down drafting combustion appliances.  Sealing between basement and
  upstairs reduces the required air flows."
  A(I.N.)  "The blower door applied to SSV system diagnostics has proven to be
  helpful to evaluate basements under extreme conditions, e.g., simulating
  winter stack effect conditions to make certain SSV will be effective
  throughout the year.  We have examples where systems failed under winter
  conditions but were fine in the summer."
  General Discussion:  Concerns were expressed as to what level of
  depressurization assured that the SSV systems would work for all seasons.   A
  degree of consensus was arrived at. The house is a box, with the volume
  under the slab another box.  The important point is that there are pressures
  in both boxes.  A rule of thumb such as pressure differences at least 0.015
  to 0.03  inches of water (4-8 Pascals) would appear sufficient for SSV
  C(K.G.)  "Movement of the neutral plane by controlling air leakage sites
  (via sealing) of the upper portions of the house can also limit the stack
  effect and thus make the radon problem less severe (and the SSV requirements
  less stringent)."
  Q(L.H.)  "Again do we have any additional answers to the question: Is the BD
  useful in evaluating SSV systems?
  A(M.Me.)  "We haven't been able to make the blower door do the SSV
  diagnostics job, but the "blower floor" has applications in this area.
  What about the use of the blower door to assess leakage areas for HRV's?"
  A(A.S.)  "The best application of HRV's comes as a result of changing the
  distribution of the air flows  in the house and not the general level of
  ventilation achieved.  Dilution effects are limited  to two or three times
  normal ventilation rates.  By  sending the air upstairs, much more can be
  achieved.  BD measurements can help resolve air leakage for different zones
  and thus help the mitigator make the right decisions."
  Q(L.H.)   "Taking grab samples around substructure under different
  conditions (ambient, pressurized, etc.) is one diagnostic approach.  How
  useful are these techniques based upon recent research?"
  A(B.T.)  "Depressurizing, and  taking grab samples does seem to bring about
  radon movement similar to winter heating season conditions.  There is a
  question as to whether this would be true in all homes.  There are also
  changes  in the radon levels in the soil to confound  the issue."
  A(R.S.)  "Pressure differences are due to stack, wind  and appliances.  Wind
  pressures are directional, thus influencing the soil on different sides of
  the house.  Ventilating the soil is also possible due  to the wind.  Using a
  negative 10 Pa standard test applies a  'research base'.  Measurements on
  walls, floors and piping in the mitigation system add  to our knowledge."
  Q(B.T.)  "Grab sampling is a integral part of  the radon research; do
  commercial mitigators see this as a useful diagnostic  approach?"
  Q(D.H.)  "Isn't the depressurized condition for grab sampling the more


Radon Diagnostics Workshop, 1987.  Phase II

  useful approach and should this be the appropriate standard?  Remember it
  again takes time to reach equilibrium  after the start of depressurization."
  C(K.G.)  "Clearly the most recently tested house in the Piedmont Study
  showed combinations of wind pressure and return duct leakage that caused
  negative 10 Pa basement readings."
  Q(D.Sa.)  "What about the situation of entirely different results when
  applying the negative 10 Pa to two houses?  One shows a radon concentration
  dropping to zero; the other a large increase in radon levels."
  A(D.H.)  "What is entering the picture is the radon source characteristics.
  In one case you have a condition of a limited radon source which is rapidly
  depleted.  In the other case you have a large radon source where the soil
  gas has reasonable transport into the house.
  C(A.T.)  "The vagaries of different soils immediately around the house, the
  location of openings through the basement walls, and the effect of freezing
  soil cover in winter may all influence the amount of radon entering the
  house.  Also local freezing could plug off leakage sites."
  Q(D.S.)  "Hollow block wall convective loop air movements were evident in
  some of the testing -- could we hear more on that subject?"
  A(B.T)  "Again depending on the air movement in the blocks, outside air
  ingestion can mean a local dilution and reduced radon concentration.  In
  other situations more radon was drawn from the soil and concentrations rose
  inside the blocks during depressurization."
  C(   )  "At this point the use of negative 10 Pa as a standard diagnostic
  procedure is inconclusive, although it would appear to be useful much of the
  Q(D.Sa.)  "How good are grab samples under ambient conditions?  Although I
  have only been in the mitigation business for seven months I have assumed
  grab samples from under the slab to be relatively invariant over the year.
  Sampling in walls has been limited in our houses."
  A(   )  "I have concluded that grab or continuous sampling under the slab is
  invaluable since one must match the final pressure field to cover the high
  level radon sources.  Relative distributions are basic, and if these were
  changing seasonally this would erode confidence in the approach."
  A(B.T.)  "In the seven LBL homes we have the ability to measure subslab
  radon concentrations when mitigation systems are turned off as well as the
  continuous measurements  in the control house.  Variations are observed."
  C(L.H.)  "Variations over 24 hours are another problem with grab samples as
  well as spacial variations."
  C(R.S.)  "Less diurnal variation is found in the radon concentration under
  the  slab than  in the basement, for example.  For most houses, I don't
  believe grab samples are very useful.  However, with more difficult
  situations, e.g., subslab lacking communication, grab samples may answer
  vital questions."
  C(L.H.)  "With mitigation systems in place, continuous readings illustrate
  SSV  altering concentrations in the wall when they are turned on because of
  communication between wall and subslab and  sweeping of basement or outside
  air  into the wall dilutes what was the higher radon concentration zone."
  Q(L.H.)  "Tracer gas methods, where do they fit in?"
  A(T.B.)  "One application is the use of freon.  The freon tracer moves under
  the  footer to  indicate drainage paths."


Radon Diagnostics Workshop, 1987.  Phase II

  A(B.T.)  "In Portland tests, tracer gas (SF6) was injected in the yard (via
  probes at different distances and depths) and monitored continually for the
  level of buildup in the house.  Transit times were measured, coupled with a
  pressure field map (depressurized the house and looked at pressures and
  probe points around the yard) to see if gas movement correlated with the
  pressure fields."
  A(T.T.)  "We have traced air flows over an entire slab using freon tracer
  looking at details of the flow paths."
  C(D.S.)  "There is a question whether tracer gas should be reserved for
  problem cases and not used as a premitigation diagnostic tool."
  Perfluorcarbon tracers are another candidate for tracer methods."
  Q(R.S.)  "SSV does seem to work in many situations.  What concerns me is
  whether these systems continue to perform over the long haul.  Will the
  systems receive proper maintenance?  We are mitigating hot houses with
  mechanical systems --is this the way to proceed in the long haul?"
  C(D.S.)  "Durability is an important consideration, partly the reason the
  diagnostic list was more complete is that we need backup strategies.  The
  government and other interests represented here can't just say that we don't
  know what to do for 10 of 50 houses based on public health.  We need backup
  mitigation approaches, and backup diagnostics.  That is one reason we have
  been discussing blower doors.  What are those other options and how are they
  going to work?  Even though SSV appears to offer an acceptable solution in a
  high percentage of homes, that is not enough.  We need other options.  Over
  the 20 year time frame we must consider cost effectiveness.  Once we have
  defined cost effectiveness we must fill in some of the options that have
  only been discussed briefly."
  C(A.C.)  "What we are looking for is a fail safe technique.  It doesn't
  matter if it.is mechanical or not, but one must know when it is working.  In
  the Washington, DC area one group is using a five dollar switch to indicate
  when suction is lost and a warming light will be activated where the
  homeowner can see it -- you do not have to go down and read a gauge.
  Remember a passive system can be overwhelmed and the homeowner not even know
  it is failing to do the job."
  Q(T.B.)  "When do you know when to use a SSV system?  What must we know
  about the soil?  A finger of sand that brings the radon to the house is one
  example (in my experience, three out of 50 houses exhibited this problem).
  Sensitivity studies are needed based on soil conditions and where the house
  is situated.  Such a study could be very helpful to mitigators.  Those in
  geology could supply source terms, those in soils could provide permeability
  factors and those in building science could supply information on leakage
  area locations and mechanical equipment factors which influence the
  pressures.  There is a lot of work to be done in this area."
  C(A.C.)  "Considering the kind of houses, we have mostly been discussing
  houses with basements which represent approximately 50% of the nationwide
  housing stock, with 35% slab on grade and 15% crawlspace.  But here  in New
  Jersey 50% are crawlspace construction.  In some states 70% are crawlspace
  houses, but we haven't even started on that part of the radon problem
  concerning dirt floor construction."
  Q(K.G.)  "Maintenance of fan systems would appear to be a problem since
  homeowners tend to ignore maintenance issues.  The fans are often in


Radon Diagnostics Workshop, 1987.  Phase II

  difficult-to-service locations and the manufacturers cite only a three-year
  guaranteed lifetime.  What is the cost for replacement at a homeowner's
  expenses -- is it several hundred dollars?"
  C(  )  "Although the guarantee is for three years, the service life is 20
  years.  The average life expectancy for this type fan is approximately 15
  C(K.G.)  "I would question long lifetime claims when the fan is working in
  an environment of high moisture and problems generated by other soil
  C(D.S.)  "The Canadians have experienced a five percent failure rate in 24
  months on their fans."

Radon Diagnostics Workshop, 1987.  Phase III

  C(M.O.)  "This particular session starts with the premise that we have a
  mitigation device in place.  Our emphasis will be on four different
  mitigation approaches and the related diagnostics.  We will limit discussion
  to the time period when  the system is being  installed without a post
  mitigation knowledge of  what radon concentration reduction has been
  achieved.  Our question  to answer is:  How well is the mitigation system
  operating?  The  four areas we will be considering are:  sealing, dilution by
  increased ventilation, basement pressurization and soil depressurization."
  C(A.S.)  "Regarding diagnostics and  the sealing approach, caulking isn't
  sealing.  The objective  of sealing is to increase the resistance of the
  house structure  to soil  gas passage  so that  it is much higher than the
  resistance of the soil.  The open area in many houses is considerable, e.g.,
  some southern houses have leakage areas equivalent to several windows being
  open.  In that case, the soil  is the more resistant element in the flow
       "In Canada, a program to  establish the  leakage area goals indicated
  that one square  centimeter of  leakage area was all that could be tolerated
  for the approach to work.  This is a very nonlinear situation, with major
  improvements in  soil gas flow  reduction only evident when a very tight
  system is achieved.  Epoxies often don't adhere properly.  All the sealing
  work must be of  high quality;  excellent surface work must be of high
  quality; excellent surface preparation is key.  Proper bonding to the
  surroundings is  vital.   Sealing has been tried and found difficult
  especially in retrofit situations.   In new construction one can design a
  hollow where you can pour the  sealant between building components.  In
  retrofit, a jackhammer may be needed to form the hollow."
  Q(M.O.)  "How do you test to make sure the sealing was done properly?"
  A(A.S.)  "First, it is recommended that you  use an experienced team that
  employs common sense in  the sealant  installation.  Secondly, use sealants
  that are the most forgiving.  We have surveyed a number of sealants, and our
  favorite was a solvent-hardening rubberized  asphalt.  The reason is that it
  was much more tolerant of the  lack of cleanliness in the application.  Other
  sealants required primers, but the recommended sealant formed its own
  primer.  These sealing systems were  tested in the lab using concrete blocks
  and then the bonds were  tested for flexibility."
  A(T.T.)  " We ran a series of  tests  in the late sixty's using huge stock
  watering troughs, and uranium  source material for the radon generation.
  Concrete, membranes, and paints were evaluated at Colorado State.  We found
  extreme variation because of bond problems and  seam sealing.  A path of
  least resistance is followed by the  soil gas/radon and small leaks were all
  that were needed for failure.  Quality control was really the only
  diagnostic.  "Holding the contractor's hand" to make certain the job was
  done right, according to specifications was  necessary until they really
  understood what  was required."
  Q(M.O.)  "What diagnostic approaches are appropriate?"
  A(T.T.)  "One approach is to use flux measurements to check the before and
  after readings.  Even pinhole  leaks  would  indicate degradation  of the seal


Radon Diagnostics Workshop, 1987.  Phase III

  using this approach."
  A(A.S.)  "These are basically water proofing materials, trowled on or poured
  into joints, and they work."
  A(A.T.)  "Bureau of Mines work on sealants should also be cited.  Sealing
  studies by John Franklin and Bob Bates of the Spokane Bureau of Mines Office
  (1976-1982 literature) dealt with sealing mine walls and pinhole leaks."
  C(  )  "Continuous readout equipment looking for freon leakage is an example
  of one diagnostic approach."
  C(A.S.)  "Radon may be its own tracer to check for leaks."
  C(M.O.)  "The next topic is radon dilution by increased ventilation."
  C(B.W.)  "First I should state that the walk through inspection is important
  to check for items that are critical to any ventilation system, not just
  heat recover ventilators (HRV) which I will be discussing.  One important
  point  is the location of air intake and exhaust to eliminate problems of
  exhaust entrainment and poor ventilation effectiveness There are
  installation instructions available for HRVS to aid the
  contractor/mitigator.  One caution is the case where there is a SSV system
  also present, the intake of the HRV must be away from the SSV radon-laden
  exhaust.  Also, the HRV intake must not be located close to the ground,
  where  leaves and debris can be picked up, blocking the intake and
  unbalancing the system."

  C(B.W.)  "	  Obviously when you do plugged flows it's nice to take
  your exhaust from the area of highest source strength.  That can be a useful
  C(M.O.)  "Let me open things up now in this -area, and see if there are any
  other  comments.  Please try to address diagnostics."
  Q(K.G.)  "We've seen a lot of furnaces out there which are depressurizing
  basements.  What effect does that have on the balance of an HRV (Heat
  Recovery Ventilator)?  Do you check that after installation?"
  A(B.W.)  "We can't, because without some kind of automatic feedback
  mechanism you can't accomadate the needs of the other appliances.  The
  industry response would be that they are not responsible for make-up air for
  the  furnace; that should be provided."
  C(A.C.)  "But I think the important question here is not the make-up air,
  but  rather, the effect of the circulating system, the depressurization of
  the basement from the pickup of return air.  I've spoken with with one HVAC
  man who was a real authority in the field, and he said that he had seen as
  high as 250 cfm picked up in crawl spaces, measured in the heating system.
  The  difference is when the fan is on and off.  It doesn't have anything to
  do with combustion.  We've seen places where we've increased tremendously
  the  inflow  through cracks by turning the furnace fan off upstairs.   It's a
  tremendous  difference, and it will affect your balance on the HRV and
  A(B-.W.)   "It will.  The  answer which we've given is that at  least with  the
  HRV  in there, you've  got a couple big holes  in the wall, which help  to
  moderate the negative pressure generated by  the circulating  or  the
  combustion air, what.  The negative pressure generated tends to  increase  the
  flow in the supply side, and decrease the flow in the  exhaust  side.   It


Radon Diagnostics Workshop, 1987.  Phase III

  helps,  but it will tend to throw it out of balance."
  Q(D.S.)  "What are the duct flow measurements you talked about?  Wouldn't
  they see that difference if there were an interaction?"
  A(B.W.)  "Yes, they could.  That's something we haven't done."
  Q(G.F.)  "Bede, have you done any comparison diagnostically with respect to
  using a continuous working level monitor versus a continuous gas monitor?
  What are the differences  [one gets] in the end results?"
  A(B.W.)  "EPA actually did some side-by-side measurements of the continuous
  working level and the continuous gas monitors in one of the houses where we
  had a heat recovery ventilator and turned it off and on.  They are very
  comparable.  But as we always saw in doing our post-mitigation diagnostics,
  the percentage decrease  in the working levels is greater that the decrease
  in the radon gas."
  Q(  )  "I don't know how  [big an] effect it would be for the small ducts,
  but when you're dealing with large industrial ducts, in terms of locating
  your traversing point, if you get it at an elbow point and count about one
  duct diameter.down, you  essentially constrain the flow very nicely.  So, you
  can do a single plane traverse simply because you tend to get it all in one
  smooth flow that's due to the changing that you're doing on it.  As you go
  across the plane, you may take more points, you don't do the normal type of
  traversing where you just do a 3 or 4 points; you have to do quite a few.
  But that does become a pretty good place to put one.  And there were single
  plane averaging pitot tubes, the brand name used industrially was
  'Anubar'that is used industrially, that you can locate some place like that
  without having to worry  about the grid flow.  These things tend to have only
  one grid that they use,  and you may have to adjust it to a finer grid scale
  when you're trying to constrain it to flow around an elbow.  But it can give
  you a good, firm fixed flow point.
  C(T.Mi)  "I was going to mention that we're not really dealing with crawl-
  space houses in terms of  the diagnostics dicussions we've been having.  But
  some of the work we've done indicates that in the crawl space the
  communication between the duct work, particularly when it penetrates the
  crawl space in many places in the house, is just incredibly good.  That's
  one of the simplest diagnostics one is going to have to do in dealing with a
  crawlspace house.  A simple tracer-gas measurement can be used to tell what
  the communication between the crawlspace and the indoors is, with HVAC on
  and off."
  Q(A.S.)  "If it's good, why do you need to measure it?"
  A(T.M.)  "To get some indication of how good it is."
  C(T.T.)  "My experience  in installing any kind of dilution system, heat
  recovery or whatever, is  that there are a couple of very helpful diagnostic
  tools.  One is the radon profile, where you have a concentration gradient
  and you know where you're highest areas are in the house."
  C(M.O)  "Let me say that most of the radon measurement things are going  to
  be covered in the next session."
  C(D'.S.)  "The radon profile that you're talking about  is actually part of
  the installation.  It's  like your suggestion about having a radon monitor,
  you would then see what  the best configuration is."
  C(T.T.)  "The second important thing in installation is that  if you're  able
  to flush the house out,  and get it essentially to background, by use  of  a


Radon Diagnostics Workshop, 1987.  Phase III

  breeze-box fan or whatever, and you can determine the in-growth rate of the
  radon into your home, you'll find through tests and a very simple formula,
  that it's about 0.8 of a cfm per picoCurie liter hour in-growth into the
  house it takes to dilute it to background and keep the house at that
  concentration.  There's a direct relationship between the in-growth rate of
  radon into the home vs how much dilution air it takes to keep that
  C(M.O).  "Let's move on to talk about basement pressurization."
  C(1.N.)  "Here we are dealing with the mitigation installation and
  diagnostics, and I'm assuming that everything has been diagnosed so that you
  have a specified, reasonable pressurization system.  Let me just back up a
  little bit:  a few things are required for a sensible pressurization system.
  The basement should be well separated from the upstairs.  There should not
  be any combustion appliances in the upstairs, lest you increase the chance
  of backdrafting.  You're more likely to be successful in pressurization if
  you don't have a forced-air system, although there are instances when
  pressurization will work even with a forced-air system.  So, assuming that
  your house meets these conditions and you've specified a pressurization
  technique, let's go back now to where we are doing the mitigation
  installation diagnostics.  The first thing to check, of course, is whether
  the pressure difference that you measured for the cfm with the blower-door
  (which Terry described previously) is in fact what you're reproducing this
  the actual installation.  Instead of using the blower door now, the blower
  door fan where you continually vary the pressure and the cfm, now you have a
  fan with one speed or it could be a variable speed.   Are you producing the
  pressure differences you expect with the blower-door measurements?  So, you
  need to take a pressure-difference measurement between upstairs and
  downstairs, and check the flow on the fan.  Then you need to go into the
  basement, and just as in the pre-mitigation diagnostics, check with a smoke
  pencil to see whether smoke is going into the cracks at that pressure
  difference.  You have to check to see what the communication is between
  upstairs and downstairs.  You would have specified that the major openings
  between upstairs and downstairs be sealed.  This would alter the
  characteristics of the pressure difference and the airflow, so if there were
  large openings between upstairs and downstairs that had been sealed, then
  less airflow would be necessary.  You could even turn the fan down to a
  lower speed to create the  same pressure difference you were obtaining using
  the blower door measurements.  There may be some obvious cracks or holes
  between the upstairs and downstairs which are still present.  In all radon
  installations  it's best  to see whether there are cracks and holes in the
  basement, and  this also might change the characteristics of the fan and the
  pressure difference  that you measured using the blower door.  The other
  things that you should check are the openings between the basement and the
  outside, for example, if there is a door that goes  to the outside that is
  very leaky, windows which  go from the basement to  the outside.  These  should
  have been sealed up  correctly during the installation of the pressurization
  system.  You  should  go upstairs and check to see that there  is no
  downdrafting  in any  combustion appliance, e.g stoves, wood  stoves,
  fireplaces.  Of course this  is very difficult to do  in  the  summer.  This
  brings up an  important point:  if some of your pre-mitigation diagnostics


Radon Diagnostics Workshop, 1987.  Phase III

  with the blower door were done during the winter season, and the actual
  installation was done later on in the year, it may be difficult to find out
  what this system's characteristics will be in the next heating season.  It
  may be necessary to come back during the next heating season to see whether
  everything is working as you thought it should.  One of those things is the
  operation of the stoves and appliances in the upper floors.  Pressurizing
  the basement should increase the effectiveness  of the flues and combustion
  appliances in the basement area.  There may be an unexpected interaction
  with the heating system.  Those things also should be looked at.  The
  location of the fan, where it is drawing air from upstairs, is very
  critical, and should be discussed with the homeowner.  Sometimes a house may
  have a laundry shoot, or there may be a natural place where a fan can be
  placed.  That might be good from the homeowner's point of view, because it
  is out of the way, but this may not be a good idea from the standpoint of
  system performance.  For example,if you use a laundry shoot that goes up
  into the second floor, you're actually increasing the stack effect on the
  whole house.  You may, in effect, be drawing more air from the basement to
  the upstairs.  Try to locate the intake of the fan at a lower level.  A
  closet also is probably not the ideal location from the standpoint of system
  performance, but is good from the homeowner's standpoint.  Sometimes these
  things change when the contractor comes in and discusses these things with
  the homeowner.
  Q(M.O.)  "Could you address the question of moisture?  There seems to be a
  potential problem of frosting and rotting out of the rim joists.  [Do you
  know of] anything you can do to evaluate that; any diagnostic technique
  which you could use to see if that's going to be a problem?"
  A(I.N.)  "You're talking about forcing moisture out.  If smoke sticks is the
  usual diagnostic tool to see whether there are large leaks into that rim
  joist area."
  Q(D.S.)  "Isn't that part of post-mitigation, because you're looking for
  some actual effects that might start to show up?
  A(M.O.)  "Maybe not.  If at the time you're doing this there is something
  you could do to find out whether there is a significant leakage, or whether
  there is a moisture problem."
  C(D.S.)  "Along these lines, if it's the pressurization, what is the flow
  rate, just what are we actually moving out?  You could do a calculation to
  find that out if you knew the exit rate of the air, the moisture content --
  maybe moisture content is an important variable, and should be covered in
  C(B.T.)  "I have several comments to make.  One is on the moisture.  First
  of all, in the homes in Spokane WA, we have not observed a change in the
  whole-house ventilation rate after we've done  this.  We've increased the
  basement ventilation rate considerably, in some cases we've doubled or
  tripled it.  The air has to leave the house somehow, and under natural
  conditions it leaves the house near the top.   In the climates typically
  found in the U.S., we haven't had problems with rotting around  the exit
  points.  We might expect to see moisture from  condensation collecting and
  causing rotting in structural members in the basement.  But I don't know
  whether it would be any worse than seeing  it at the top of the  structure
  under natural exfiltrating conditions."


Radon Diagnostics Workshop, 1987.  Phase III

  C(T.B.)  "We have seen that frequently, under natural conditions."
  C(D.Sa.)  "I don't think that is necessarily true, because you're looking
  for a condensing surface, a cold surface against which this warm air will be
  pushed.  Up in the attic, there is no condensing surface;  there you've got
  the attic ceiling and then the insulation sitting on top of that.  There is
  no surface on top of that; there's a big space up there."
  C(A.S.)  "But the insulation is one condensing surface."
  C(D.Sa.)  "Yes, but it's not like having a cold wall there with insulation,
  so that the air passes through the insulation and then hits a cold surface."
  C(T.B.)  "The condensation happens right on the underside of the roof
  sheathing.  I've seen plenty of moisture damage in attics."
  C(D.H.)  "We agree with Terry and have published a number of reports on
  attic  (and crawlspace) moisture problems.
  D(D.Sa.)  "But at least attics are ventilated, whereas the wall is not
  ventilated, so I think there's a bigger potential."
  C(B.T.)  "It might happen, but I think that [should be] a follow-up
  measurement to this.  We've been doing this only nine months, so we really
  haven't been through it."
  C(  )   "Someone brought up an important point.  If you could, with a smoke
  pencil  or other means, identify the large leakage paths existing in the
  house,  and plug the big holes, that might be of some value.  As we know from
  the moisture-damaged houses of the far north, the big problems happen when
  there's a big leakage path.  The other thing is that in the houses that
  you've  done, you're not going to see rot yet, because it takes a long time
  to get  to that.  That's not to say that it won't happen."
  Q(R.Si.)  "I was wondering whether anyone had measured a bona fide change in
  moisture before and after pressurization."
  C(T.B.)  "We've changed the whole humidity dynamic.  A great deal of the
  moisture in that building is probably entering with that soil gas.  Now that
  we've prevented that, we may have cut the moisture source strength by a
  factor  of two.  We have countervaling physical principles going on here,
  with no way of knowing whether we'll have a problem."
  C(  )   "We have measured relative humidity in upper floors and basements and
  overpressures and we've seen declines almost universally in basement
  C(B.T.)  "I have a few other comments, and the first one applies not only to
  heat exchangers but also to basement pressurization.  You have to decide
  what overpressures you're going to operate at, and what are acceptable
  overpressures, and what are the maximum flow rates that you can live with
  when you actually set up your blower-door.  Is 300 cfm too much, or 400 cfm?
  For economics, we use something like 300 or 400 cfm as an upper bound.  With
  anything more than that you'll have a lot of drafts, and you also pay an
  energy  penalty to move this large volume of air.  Another question concerns
  the pressure:  what pressure do you have to develop in the basement to
  override 90% of the conditions.  We're using something like 3 pascals
  overpressure  (difference between basement air and outside air) , but that may
  not be  enough, and that may be suitable only in certain climates.  As you  go
  further north, you may have to go even higher, to override more extreme
  C(K.G.)  "We have a couple diagnostic questions.  Being from the energy


Radon Diagnostics Workshop, 1987   Phase III

  field, we worry about home-owner comfort, and I think the location of the
  fan intake is important.  As Brad mentions, should we check for a local
  drafty situation?  Also, regarding the HVAC operation, most of our newer
  homes have central air conditioning, so it would be a problem all year
  round, not just during the heating season.  Should we check the HVAC
  operation and its effect on the pressurization system?"
  C(T.B.)  "That goes right along with my diagnostics question.  What happens
  to the pressure field when you turn on the furnace?  And what happens if you
  turn on the  'Jenaire' all of a sudden you're exhausting 400 or 500 cubic
  feet per minute from the upstairs chamber in competition with the fan that's
  blowing air  down into the basement?  The question is, how do we test for the
  impact of other exhaust  devices on our pressurization system?  I suppose
  that the answer is to turn them all on at once and see."
  C(M.O.)  "I'm sorry, but our time is up on this topic.  Now we need to move
  on to soil depressurization."
  C(B.T.)  "We talked about this a bit already yesterday.  The most important
  things to check are: how extensive a pressure field have you developed in
  the soil?  Is that strong enough to resist the competing pressures from
  wintertime stack effect  and from exhaust appliances?  Also, do you have some
  sort of  're-entrainment' That is, is the fan you're using somehow mining
  high concentrations of  soil gas and blowing it into the house, or is it
  coming back  in from from outside?  Those are the three things you want to
  test for, and I do that  typically by using smoke sticks.  If I were stranded
  in an abandoned radon house, and could select only one thing to have with
  me, it would be smoke sticks (not Bayer Asperin) and a respirator.
  Magnehelics  and incline  manometers both have problems at the low end range.
  You can tap  Magnehelics  and the needle will move and stay stuck in a
  different spot.  Incline manometers mean that everything you own has red
  gauge oil on it.  And they are slow to move if you're moving any air column,
  you really have to wait  for them to stabilize.  Although they are expensive,
  the electronic sensors maintain calibration very well, and respond
  instantaneously.  I think they are worth the money.
       You can check with  all those things.  You can turn on all the exhaust
  devices in the house, or artificially induce with a fan a  wintertime-type
  negative pressure, to see if you can overwhelm it the mitigation system,
  and have soil gas entering where it used to be leaving, with your soil
  C(D.S.)  "if you have the design pressure  in the weakest^part of your
  system, then it is not  going to be overcome by any wintertime design
  conditions.  For re-entrainment I check with the freon tracer.  Two
  important things to remember are that 1) silicone will give you a false
  positive; it will beep  like crazy at silicone, and 2) if freon comes into
  contact with an open flame, phosgene is  formed, which is not very nice
  Q(M.O)  "Is  there further diagnostic imput?"
  A(D.Sa.)  "I'd like to  say something about radon mapping.  We find that you
  don't want to fix something which is not broken.  If you have multiple
  slabs, crawl spaces, holes, etc. you can go in there and make sniffer
  measurements and decide  where to mitigate  and where not to mitigate."
  C(I.N.)  "We were talking about the dangers of tracer gasses.  We should be


Radon Diagnostics Workshop, 1987.  Phase III

  glad that freon is not among those which react with ozone."
  C(T.B.)  "It depends on the one which you are using.  Probably Rll and R12
  will soon be banned.  You can either use an R22, which is more acceptable,
  ... the ozone is a serious issue for me, and I don't lightly dump lots of
  freon into the atmosphere."
  C(L.K.)  "Along the lines of what Terry was just saying about setting a
  match to silicone, I think people should be cautious about the sealant they
  use; make sure that it is appropriate for internal use.  In my region the
  Center for Disease Control is looking into a log cabin, where someone used
  caulking on the inside of the house that was meant for external use only.
  The caulking may have caused a child to be born with leukemia."
  C(D.S.)  "It has been stressed quality assurance and quality control is
  important in the installation phase.  It seems to me that many leaks could
  be avoided by making sure that it's done right to begin with.  It seems to
  me that that should be one of the diagnostics in the installation.  I'd like
  to ask the mitigators how often they've had to go back and fix things that
  weren't done right along those lines."
  A(D.Sa.)  "Do fifty percent of the systems have some sort of leaks?"
  C(  )  "I think that's too high -- maybe 25%".
  C(M.Me)  "Our standard procedure is to check out the system with freon when
  it's installed.  We do double-check sometimes; for instance, when we have an
  installer putting in the system, the installer is supposed to check out the
  system with freon before leaving the site, and we generally return within 48
  or 72 hours and do an independent quality control check.  We've found leaks
  using freon in the air perhaps 10% of the time.  These leaks occur in two
  places: one is at the joint where the fan is coupled to the pipe going
  outside, and the second one is at the band joists where the pipe is exiting
  the house.  That we find is frequently a difficult installation point,
  because you're working with bends in the pipe in constricted space, often
  between floor joists).  It's the point where the utmost care has to be
  C(A.S.)  "I would comment that I really admire people who have the courage
  to install fan systems with the portions internal that are under pressure.
  I've never had enough courage for that and we've always mounted the fan
  C(M.Me)  "We're losing our courage.(laughter)  The pictures we showed
  yesterday had that roof-mounted fan for that reason.  The problem is that in
  terms of the installation costs, it's considerably more expensive, and so
  we're generally offering people three alternatives:  we say it's cheapest
  and simplest to out through the side of the house, but here there are the
  most serious concerns about venting.  The second best  is to go up through
  the roof with the fan mounted  in non-living space, an  attic or crawl space.
  Preferable is to get the fan ouside the house, mounted on the roof.  Each
  step buys you an additional level of protection, at an additional cost."
  C(M.M.)  "I'm not entirely sure whether  ... although obviously it must be
  smaller, we've seen no evidence in  our  installations where all our fans  are
  ground-mounted, that this prevents  you  from achieving  4 pCi/L per liter  or
  less, on average."
  C(M.M.)  "With ground-mounted  [fans], our concern is with human traffic.
  Most of our clients, in  fact, have  small children.  That seems to be a


Radon Diagnostics Workshop, 1987.  Phase III

  driving force in installing mitigation systems in that 5 to 40 pCi/L range."
  C(M.O.)  "We have time for just a few more questions."
  C(RSi)  "I have a comment on the problems with the side mounts.  We've found
  a lot of re-entrainment six or eight feet away around the collar joists,  or
  band joists, or the plate foundation interface area.  So, we've elected, if
  at all possible, not to give the home-owner an option.  We price the job
  going through the roof system."
  C(A.C.)  "The new manual will show that as the only option."
  C(R.Si)  "Also, as was mentioned earlier, the problem going along with that
  is inadvertant exposure of kids, even if there are plants or if the area is
  protected.  That's not a long-term protection mechanism.  The  [plants] could
  be removed, and the area could then be used as a play area."
  C(D.S.)  "Just one more point, along the lines of the this quality
  assurance, quality control.  Someone mentioned double-checking:  that should
  be routine.  And there should be a checklist.  A lot of this seems to depend
  on the experts: 'well, I know what should be done'.  But there's no record
  of what was done, and there should be a checklist as a diagnostic that
  should be followed."
  C(T.B.)  "Actually, Bill Brodhead made a checklist for the ORP course for
  each of these mitigation techniques.  There's at least something written
  down on paper."
  C(D.S.)  "A course is one thing, and practice is something else."
  Q(T.B.)  "Bill, do you actually use your checklist?"  (laughter)
  Q(L.H.) "I have another quick question for the mitigators.  Are subslab
  ventilation and dampers installed routinely in the system to balance the
  flow during the installation?"
  A(R.Si)  "It's routine for us.  We install damper systems to balance the
  depressurized area, depending on what we're dealing with.  It  could depend
  on whether it's going into an adjoining slab, or an area that  doesn't have
  the same type of pourous fill as another area, or possibly the specific area
  that it's dealing with, so that we can adjust and have relatively uniform
  flow throughout the system."
  Q(L.H.)  "Do you do that on the day of installation?"
  C(M.O.)  "Right."
  C(M.O.)  "Do you have a rule of thumb on dampers, as  far as how many you
  would have in a system?"
  C(R.Si)  "No, it's pretty specific as to what we're dealing with at the
  time.  We install dampers in every lateral."
  C(M.O.)  "OK, that's what I was  [asking about]."
  C(R.Si.)  "The other thing is that if it's a direct line down  from a fan, in
  my experience, we'd have more direct draw from the straightest run of pipe,
  and we want to be able to divert that through areas."
  C(M.O.)  "Our time is up, that ends the Phase III Diagnostics  Section."

Radon Diagnostics Workshop, 1987.  Phase IV

            POST MITIGATION DIAGNOSTICS - Bruce Henschel, Chairman
  C(B.H.)  Four basic diagnostic issues will be discussed here.  First, what
  is the universe of diagnostic techniques that might be considered under
  post-mitigation diagnostics?  Second, is each technique practical and cost
  effective for a commercial mitigator to use?  Third, our emphasis will cover
  the confidence we have in the technique, the experience to date, the
  improvements needed, and the interpretation of the results.  Fourth, who
  should use the technique?  The commercial mitigator, the homeowner (long
  term items), or the research community?  What kind of diagnostics should be
  used if the system is working, but not achieving the 4 pCi/L guideline value
  is an interesting question but should be referred back to the earlier
  diagnostic categories.
      "In order to conserve our discussion time I will start the informal talk
  on the list of diagnostic techniques  for post mitigation.  What are the
  universe of techniques that fall into this category of diagnostics?  The
  obvious techniques include measurement of Rn and/or Rn progeny.  Should we
  measure Rn gas or Rn progeny or both?  Where should we make the measurements
  --in the living space, or the basement; or from a research standpoint, in
  walls or under the slab?  What is the timing and duration of these
  measurements (i.e., short term, long term measurements)?  What levels are we
  looking for -- does every measurement have to be less than 4 pCi/L?
      "Another diagnostic technique is evaluating the effect of weather and
  events such as appliance use on the radon inflow.
      "A third diagnostic item is evaluation of mitigation system fan size.
      "A fourth item is the evaluation of back drafting of combustion
  appliances with the mitigation system operating and depressurizing part of
  the house.
      "A fifth diagnostic item is visual inspection, seal functioning over
  time.  Moisture problems such as band joist rot due to moisture extracted by
  the mitigation system, etc. and a sixth, the effect of SSV on the soil
  around the foundation -- possible freezing problems, drying out the soil,
      "Finally, as a general category, other side effects such as ill effects
  from the caulking, etc."
  Q(D.S.)  "This list has many items the commercial sector may not be
  interested in.  Who has the long term responsibility for the system
  operation and side effects?"
  A(B.H.)  "I am assuming that the homeowner may have to take the
  responsibility for the long term items.  In addition, researchers may have
  similar interests for the long term.  The techniques listed that should have
  the most interest to commercial mitigators are measurements of radon and
  radon progeny, and assessment of weather, appliances, and back drafting.
  Their interest in optimal fan sizing may prove to be a question mark."
  Q(A.C.)  "What part of the post-mitigation diagnostics is the commercial
  mitigators responsibility, and what part is somebody elses?  David Saum,
  what do you guarantee as far as reduction of radon below a certain level?"
  A(D.Sa.)  " My guarantee is for a year, nominally.  Long term testing is an
  interesting area, but we have had trouble finding a group who routinely
  handles the long term.  We provide charcoal cannisters and alpha track


Radon Diagnostics Workshop, 1987.  Phase IV

  measurement devices for the intermediate term."
  C(A.C.)  "Part of the EPA demonstration program will be to continue yearly
  testing for at least five years on all of the houses that were mitigated in
  the studies.  We will perform a three-month alpha track survey during the
  winter season.  In the New York study we are going back to resurvey what
  they did four years ago to see how well the mitigation has held up and to
  determine if there are any problems."
  C(T.B.)  "When it comes to problems,  the homeowners determine who they will
  turn to for assistance.  Sunday morning calls are a real problem for the
  A(A.C.)  "In most states the mitigator doesn't have any responsibility
  beyond one year."
  C(T.B.)  "Unfortunately most homeowners do not believe that.  I have calls
  on houses I built five years ago, but now the homeowner has installed a
  dimmer switch that bothers his radio and its my fault.  The homeowner will
  hold the person that did the work responsible as long as possible."
  A(M.Me.)  "Let me quickly explain which tests we do and why.  Once our
  system has gone through our quality control check, we supply the homeowner
  with charcoal canisters which they place in the house for checking
  performance over the intermediate term.  Once we get back an indication that
  radon levels are below 4 pCi/L, then we install alpha track for a three-
  month evaluation.  Since we are often heading into spring-summer,  we ask the
  homeowner to wait until the next winter to make this three-month test.  We
  have discussed radon progeny measurements but since we don't have the before
  measurement of radon progeny, an extensive set of after measurements creates
  a new set of problems for ourselves.   The before diagnostics limit what post
  diagnostics are appropriate.  The post set of measurements are limited to
  radon, not pressures, etc.  We are 'listening for side effects', but that is
  the extent of it."
  C(  )  "In the case of 12 mitigation companies in New Jersey, the testing is
  far more limited than that described here.  Very few are doing much in the
  the way of diagnostics.  It is very simple out there, let's get in, put
  something in place, let the homeowner see what the results are.  No one is
  doing work adjusting dampers, two are doing freon post-tests.  There isn't a
  lot of diagnostics going on out there."
  C(T.B.)  "Chick and I surveyed a number of installations in New Jersey.
  About half the systems weren't working properly but could have been if
  simple post-mitigation diagnostics had been used, such as checking the
  effect of the 'suction away from the suction hole."
  C( )  "Even the simple post-mitigation measurement of radon concentration
  has been left up to the homeowner.  One example of really simple diagnostics
  used by a company who has installed 400 SSV systems is to put two five-
  gallon buckets of water down the 4-inch diameter  suction hole.  If it moves
  quickly into the soil this means good communication and they proceed.  If
  the water isn't quickly drained they move out  to  the edge near  the footer
  and drill additional suction holes counting on the soil to have fallen away
  from the footer and thus providing good perimeter communication.  They might
  also move to trenching.  What ever is done on radon or radon progeny  is the
  responsibility of the homeowner."
  C(R.Si)  "Check lists are important for each specific system."


Radon Diagnostics Workshop, 1987.  Phase IV

  C(R.S.)  "A competent diagnostician should be checking that the whole house
  works successfully, e.g., interaction between the mitigation systems and
  appliances, etc.  There is a moral responsibility for following up the
  higher radon houses, say greater than 50 pCi/L.  Both the research community
  and government officials must make the commitment to provide the kind of
  understanding necessary through a long-term radon measurement program to
  evaluate these mechanical mitigation systems over the long term."
  C(T.T.)  "I like radon measurements for post-mitigation diagnostics.  If you
  kill the parent you don't have to put up with the children.  We don't need
  to measure working levels;  we have never accounted for the unattached
  fraction of daughter products.   I use a grab sample profile of radon and
  compare it to the pre-mitigation data.  I have had 100% success in
  predicting whether the home will exceed the annual radon average based on
  radon data (employed on 80% of a 600 home sample, involved with mine
  tailings).  I also look for hot spots in the radon profile survey."
  Q(D.S.)  "Are you looking at an annual performance?  That is where the 4
  pCi/L came from?"
  A.(T.T.)  "I am comparing to a year-long Ripsu sampling."
  C(D.S.)  "We are talking about annual average and not a grab sample and then
  you are done. "
  C(T.T.)  "I thought we were talking about several phases of post mitigation.
  I am suggesting a method to let you know where you are."
  C(R.S.)  "A grab sample isn't the whole story.  One must consider longer
  term measurements such as alpha trak in several locations as a minimum."
  C(M.C.)  "New Jersey has requested each mitigator to supply before-ahd-
  after measurements to show what has been achieved.  These are mostly carbon
  canister measurements of radon and not longer-term measurements."
  C(T.B.)  "We have a serious problem in the private sector with conflict of
  interest.  If I were doing commercial mitigation work I would make sure the
  pre-mitigation reading was high and all post-mitigation reading would be
  low.  The potential for fraud is extremely high after selling thousands of
  dollars of mitigation.  We need independent radon testing because there is
  the whole question of liability if you take your own measurements."
  Q(T.T.)  "What  is an annual average?  What does it mean when we obtain it?
  Is it reproducible the next year?"
  A( )   "No, there is no such thing as an annual average is the answer."
  Q(I.N.)  "Since there are a number of EPA people here, in subsequent
  revisions of protocols is EPA going to reconcile  .02WL and 4 pCi/L?  EPA
  should  resolve  the question.  In some areas it pays to measure radon progeny
  because of the  equilibrium fraction is less than 50%.  EPA should settle on
  either  radon or radon progeny.  These questions are becoming central to real
  estate  transactions."
  A(   )   "The guideline is written in terms of 4 pCi/L for indoor radon, the
  type we are discussing."
  A(A.C.)   "No, in every case it's given both ways."
  A(W.L.)   "The conception in the research community considers the ultimate
  dose to the lungs  and risk.  Because of compensating factors the dose models
  indicate that radon gas measurement is probably better as an approximation
  to dose than radon progeny in contrast to what we thought a few years ago.
  In a sense there is a very strong movement toward radon measurement and


Radon Diagnostics Workshop, 1987.  Phase IV

  guides because of its practicality but also because it makes more sense from
  ultimate risk."
  A(A.C.)  "From the EPA demonstration programs, the decision making is based
  on radon, continuous monitoring or canisters."
  C(B.H.)  "The measurement of radon and ventilation effects is a critical
  area for continued research.  What happens to WL and unattached fraction are
  closely related to ventilation taking place in the space."
  Q(  )  "Don't we know what is the unattached fraction?  The health community
  is saying probably the unattached fraction makes up for the difference in
  ratio and consequently either one gives you essentially the same thing.
  What happens to the unattached fraction depends on the system --is there a
  filter present -- these points need to be looked into."
  C(R.S.)  "We can't rely on WL measurements to have any assurance that you
  have made any improvement in the radon situation."
  Q(A.C.)  "Are any real estate companies requiring WL measurement?"
  A(  )  "Yes, in Pennsylvania.  A real estate relocation company is using WL
  measurements with continuous monitoring over one day.  This is one of the
  two largest relocation real estate firms in the country.  Home Equity
  Q(  )  "What instrument are they using?"
  C(  )  "That depends on the contractor, they don't do their own testing."
  (Some discussion on the size of the real estate market handled by such
  C(B.H.)  "Summarizing, radon is easier to measure and may be a better
  indicator given that you have to make a fairly simple measurement -- you
  can't be measuring WL as a function of particle size in every house the
  commercial mitigator goes into."
  Q(T.B.)  "I have almost given up on summertime measurements because of the
  seasonal variability.  Who is going to do long term monitoring in buildings?
  I don't think it is the mitigator's job."
  Q(  )  "That is an important issue and gets back to the question of isn't it
  the homeowner's responsibility to measure his house over the longer term?"
  A(T.B)   "The mitigator leaving canisters for follow up measurements was one
  idea advanced.  A commercial house offering that service is also very
  interesting.  New Jersey's follow up program is another example of longer
  term testing."
  A(A.C.)  "Your getting back to the question of "is it a legal
  responsibility?  EPA's program is a voluntary program and always will be
  because we don't have the legislative mandate to set a regulation.  Some
  states are setting regulations.  There will not, as far as we know, ever be
  a Federal regulation."
  C(J.H.)  "New Jersey has done 1400 confirmatory tests and 200 post remedial
  tests.  One major problem is that the homeowner doesn't want the government
  to know the level of radon in their house.  They don't trust the government
  unless they need some financial support.  Interesting findings from the post
  remedial tests; about 47% used sealing, 18% used HRVs, 22% used SSV,  the
  rest used other ventilation systems or methods.  Thirty-nine percent did the
  remediation themselves even though the homeowners were well-off financially.
  These owners are concerned with cost.  Before mitigation 97% were above 4
  pCi/L,  while after mitigation 48% were above 4 pCi/L."


Radon Diagnostics Workshop, 1987.  Phase IV

  C(A.C.)  "About half made it to the guideline."
  C(J.H.)  "The before levels were between 3 and 400 pCi/L."
  C(A.C.)  "The goal of the mitigator in any home is not for a given percent
  reduction, but is to get the post-reading as low as possible, and at least
  below 4 pCi/L."
  Q(D.S.)  "Cost effectiveness was cited as one of the issues.  You must put
  mitigation on an objective basis.  We really haven't done that in the U.S.
  Sweden is doing that.  Are there any ideas at this point of how to pursue
  that goal?"
  C(A.T.)  "In some places dehydration will occur to depths of several meters.
  It could significantly increase radon transport."
  Q(B.T)  "Why wouldn't it decrease the source strength because of emination
  A(A.T.)  "You are talking about moisture changes of a few percent while I am
  talking about changes from 60% to 30%."
  C(T.B.)  "You get condensation on top of the SSV pipe.  If you've done the
  installation correctly the moisture runs back into the soil, otherwise it
  interferes with the fan and you'll hve to fix it."
  C(A.T.)  "I don't know if it is a real effect, all I know is if it does
  dehydrate the sail it will have an influence on the source term."
  C(A.C.)  "Larry Kaplan reported that in one installation he was monitoring
  the SSV system produced 2 1/2 gallons of condensate per day."
  Q(T.B.)  "Was it running back into the soil?"
  A(A.C.)  "He was draining it away, but I don't know exactly how he was doing
  C(B.H.)  "In terms of the diagnostics we would use to evaluate this, it
  might be in the realm of the developers and the researchers either measuring
  changes in the source term, or the moisture content of the soil or something
  to that effect over the course of the project."
  C(A.T.)  "If you're doing periodic monitoring over years, and finding the
  radon levels are rising and the mechanical mitigation system is working,
  this could be the reason for the source terms changes.
  C(  )  "I think the opposite situation takes place.  As the soil drys out
  the suction system becomes more effective and reaches out further and the
  performance gets better."
  C(A.T.)  "I claim some knowledge only of the source term."
  C(A.C.)  "As long as you have a negative pressure difference across  floor
  and wall cracks it probably doesn't really matter how dry you get the soil.
  Even if the source strength increases it doesn't mean more radon will enter
  "the house. "
  C(A.T.)   "That's a good pointp; the key is that the gradient is toward  the
  Q(B.H.)   "Our time is running out and I would like to turn the discussion
  back to radon monitoring, something near and dear to  everyone.  The  question
  is where do we monitor?  For those that are doing monitoring as part of
  commercial installations where do you monitor  - upstairs, basement,  both
  A(T.T.)   "Usually we monitor 6 to 8 places in the house.  I  think many
  people are overlooking that radon levels can increase in living spaces  while
  being reduced in the lower house locations.  I believe a profile of  radon


Radon Diagnostics Workshop, 1987.  Phase IV

  levels is necessary, not just basement measurements."
  A(D.Sa.)  "We try to make radon measurements in a couple of places that were
  measured before, often on each floor."
  A(M.Me.)  "Always a minimum of two charcoal canisters are used, plus one
  alpha track which the homeowner decides on the placement."
  A(I.N.)  "We try to follow the EPA protocalls."
  Q(  )  "Oh my God, I'm sorry for you."
  Q(  )  "Which one?"
  C(I.N;)  "It is rather difficult.  There are two types of measurements the
  EPA suggests.  One is the screening measurement which is done at the lowest
  level of the house.  The other is the so-called follow up measurements which
  in the present protocol is the pre-mitigation follow up.  So you would try
  to duplicate those location measurements in the post-mitigation measurements
  with the charcoal canisters.  The measurement of radon or radon progeny is
  still a question."
  C(  )  "One of the problems that drives the pre- and post-mitigation
  measurements is the time delay that is necessary to purge the lucas cell
  after measuring a hot spot.  There is a definite research need to develop a
  rapid radon measurement system which doesn't have the problem measuring the
  radon daughters.  That development would change the whole complextion of
  what pre- and post-mitigation measurements would be made."
  C(A.S.)  "Eberline appearently has been working on an electrostatic cell
  that removes the daughters and measures radon."
  C(A.T.)  "Paul Tease claims a patent on that."
  C(D.Sa)  "Sniffing measurements limited to only a few minutes has allowed us
  to quickly clear the cell even when covering ranges from 10 to a 1000 pCi/L.
 v We also seem to see significant reductions under the slab.  You don't
 ' agree?"
  C(  )  "The holes drilled into slab and walls for diagnostics have been
  plugged with putty or tape until after the system is installed.  The
  principal.measurements have been pressure but where we have interesting
  houses we have gone back, time permitting, and we sniff there on how quickly
  radon levels drop and how far.
  Q(A.C.)  "What is the highest levels you've measured after several months?"
  A(A.S.)  "50,000 pCi/L near the beginning of monitoring in the spring, and
  35,000 the following fall out of the subslab."
  C(A.C.)  "We have seen some very high levels even after long periods of
  C(B.W.)  "I would like to tell the story of a building contractor in
  Pennsylvania who filled out a form to his insurance company that he was now
  going to install radon mitigation systems.  The next day he received notice
  his insurance was cancelled.  We are in the business of installing
  ventilation systems is the response to that issue."
  C(W.L.)  "I want to go back to the issue of long term effectiveness of
  mitigation.  It is clear there is not going to be federal regulation on this
  issue in the near future.  States are taking some actions; some will take
  different actions and that may not be a very satisfactory situation.  That
  raises the question of whether the industry could develop a voluntary
  standard, especially the cream of the crop which is here."
  A(B.T.)  "The ASTM task group is attempting to look at  a  standard for long


Radon Diagnostics Workshop, 1987.  Phase IV

  term measurements.
  C(A.C.)  "They will never get 50% of the mitigators to belong."
  C(  )  "But that's better than 10%."
  C(  )  "But it's possible that the EPA could come out with a recommendation
  that the states could put into their regulations for long term
  C(D.S.)  "EPA began to get involved with ASTM 1 1/2 years ago in that same
  subcommittee.   I haven't heard of any change in that policy to work through
  ASTM to set up such guidelines."
  C(A.C.)  "Eighty percent of the mitigators have never heard of ASTM."
  C(D.Sa.)  "If we had the guideline in hand, it might take three years to
  move to approval.  The process is very slow."
  C(  )  "A group of leading mitigators is one idea that has been discussed as
  a voluntary type of control.  Dissemenation and gathering of information as
  well as a form of regulating body that would overse the type of mitigation
  installations and establish minimum standards.   We are looking for
  C(T.M.)  "Such an organization would help to upgrade the image of this new
  industry as well as raise the prestige of mitigators who subscribe to the


                          FROM THE PIEDMONT STUDY
      Lynn M.  Hubbard,  Tony M.  Lovell,  David L.  Bohac,  Craig A. Decker
           Kenneth G. Gadsby, David T. Harrje, Robert H. Socolow
                Center for Energy and Environmental Studies
                            Princeton University

     The Piedmont Study refers to the detailed radon mitigation and
diagnostic study conducted in 14 homes in the New Jersey Piedmont area from
9/86 to 9/87.  Seven homes were investigated by Lawrence Berkeley Laboratory
and a second set of seven homes were studied by Oak Ridge National Labs and
Princeton University.  This data-intensive, instrumented study was
cooperatively funded by the U.S. Environmental Protection Agency, the U.S.
Department of Energy, and the New Jersey Department of Environmental

     Instrumented measurements included:  (1) basement and upstairs radon;
(2) differential pressures across the basement/subslab, basement/upstairs
and basement/outdoor interfaces;  (3) temperatures at basement, upstairs and
outdoor locations; and (4) central air handler usage.  A weather station was
located at house i?5, monitoring:  (1) wind speed and direction,  (2)
barometric pressure,  (3) precipitation,  (4) soil temperature, and (5)
outdoor temperature and relative humidity.  A time-averaged value of all of
the above parameters was recorded every 30 min.  Several additional
parameters were monitored on an intermittent basis in all or selected homes.
These included multizone air infiltration rates which have been measured in
all homes using passive perfluorocarbon tracers (PFT), and in one home using
a constant concentration tracer gas system (CCTG).

     The purpose of the analysis of the continuous time series data set
available from the Piedmont Study is to provide insight into both the
usefulness and accuracy of some of the diagnostic measurements made by
practitioners as well as insight on the interaction of various measured
parameters with the time-varying radon concentration.  The analysis
presented here was performed at Princeton University using the data from the
seven Princeton/ORNL research homes.  These homes were chosen to be of
similar basement types, and Table 1 compares substructure specifics and
other house parameters.

                   Table  1.   Summary  of house parameters.
                     (h'1)0-  Soil
                    -50 Pa.  Perm.
 I    Basement W/Slab,  Float. Slab,
      Att. Gar. W/Slab      Sump

 II   Basement,             Sump
      Att. Gar. W/Slab
 III- Basement,         Float. Slab,
      Att. Gar. W./Slab     Sump
 IV   Basement W/Slab,    2 Sumps
      Att.  Gar. W/Slab
                                Cent.  F.A.

                                Cent.  F.A.
                                Gas,  W/AC
                                Cent.  F.A.
                                Cent.  F.A.,
                                Oil W/AC,
                               Auto Setback



 V    Basement,         Float. Slab,
      Att. Gar. W/Slab
                                Cent.  F.A.,
                               Elec.  Ht Pump,   U:25
                               Auto Setback    U:36
 VI   Basement W/Crawl   2 Ht Exc.
      Att. Gar. W/Slab     Sump
 VII  Basement W/Crawl  Float. Slab,
      Att. Gar. W/Slab     Sump
                        (Part. Seal)
                                Cent.  F.A.,    W Ht Exc  19.8
                                Oil, W/AC,    B:25,  U:14
                               Auto Setback   W/0 Ht Exc
                                Cent.  F.A.,
                                Gas,  W/AC,
a  control house
b  B - basement or crawlspace,  U - 1st floor above grade,
        A - 2nd floor above grade
c.  depressurization only, basement door closed, blower door on main
    entrance, Nov., 1986 measurements.

     One question which is often asked by both researchers and practitioners
regards the difference in accuracy in a two day versus a four day
measurement of the average radon concentration.  How much better is a four
day average over a two day average?  Without addressing the question of the
accuracy of the measurement device itself, we have used the Piedmont data on
continuous radon measurements to determine how variable the two day versus
four day averages are over different seasons.

     Figure 1 plots the differences between nested two day and four day
averages for the control house over 200 days of the study.  Each point is
the difference between the average radon level over a two day period and the
average over the four days centered about the two day span.  The average
difference is zero if a long enough time span is considered,  but any given
difference can be either positive or negative, with an alternation in sign
being the norm.  The standard deviations noted on the figure are those
associated with the DIFFERENCES, not the radon levels over the period.  For
the winter, the deviation of 1.40 pCi/L is 6.4% of the radon level.  This
represents the scatter attributable to your choice of two versus four day
sample intervals.

     Figure 2 is the scatter plot of the two day averages versus the
associated four day averages.   The differences between the averages account
for the deviation of the points from the straight line.  The standard
deviations given are those of the daily radon levels over each season.
Different symbols are used for each season to show how the radon levels
changed over the long term.

     Figure 3 shows a four day span of basement radon levels in two homes
during a period of no rainfall.   Although one of the radon curves has a very
dynamic character and the other is somewhat static, the differences between
the 2 and 4 day averages for BOTH curves is negligible.

     Figure 4 shows a basement radon level reacting strongly to rainfall.
The spike produced by rainfall dominates the curve, and the choice of either
a 2, 3 or 4 day sample interval makes about a 10% difference in the actual
average radon level for this house during one rainstorm.  This 10% figure is
comparable or less then the statistical variations commonly found in the
readings of passive sampling devices placed side by side, however it could
become significant as the error in the passive sampling devices improves.
The behavior of House 7 during rainfall, displayed in Figure 4, had the
largest response to rain out of the seven Princeton/ORNL homes.

     The top box in Figure 5 shows the variation in the basement and
upstairs daily radon concentration during one week in February.  The Julian
date is shown at the bottom.  The basement radon concentration has a
distinct diurnal periodicity with the daily minimum varying from the maximum
by a factor of between 1.5 and 2.  Use of the heating system appears to be
part of this diurnal cycle.  The heating system consists of an oil
combustion unit with a heat pump, located in the basement, with a forced air
distribution system throughout the house.  During the sleeping hours the
system is manually shut off, and the basement radon slowly builds up.  When
the homeowner rises between 7  and 8 a.m. the oil combustion unit is manually


turned on and left on until the upstairs temperature reaches approximately
70 F.  The system is then manually switched over to the heat pump, which
continues running automatically on a thermostat throughout the day.  If the
outside temperature drops below 30 F during that time,  the system
automatically switches over to the oil burner again.  Before retiring at
night, the homeowner again manually turns off the entire heating system.
The second box in Figure 5 shows the basement infiltration (in air changes
per hour, ACH) averaged over hourly time periods using the constant
concentration tracer gas system (CCTG).   The third box plots the difference
between the upstairs minus the outdoors temperature (top curve), and the
percent time in each 30 minute time period that air is flowing through the
air handler (bottom curve, with units given on the right ordinate).  This
measurement does not distinguish between oil combustion and heat pump use.
The bottom graph plots the outdoor minus basement and subslab minus basement
pressure differences in Pascals.  The more positive this difference is, the
greater the depressurization of the basement relative to the subslab or

     These graphs tell the following story.  The basement radon builds up
during the night, when there is no heater operation.  Once the heater comes
on the basement air gets mixed with the upstairs air, and a slight buildup
in the upstairs radon concentration can be seen to occur during the period
when the basement radon is decreasing (top graph).  The basement is
depressurized relative to the outdoors, subslab, (bottom graph) and upstairs
(not shown) during the cold winter days plotted here.  Deviations from this
baseline occur in the initial combustion stage of the heater use.  (Note:
the overall increased outdoor - basement pressure difference over the period
between days 54.5 to 56.0 corresponds to a strong and steady wind from the
northwest.  This correlated behavior also shows up in other time periods.)

     Three processes can occur during heater use which affect the basement
radon concentration.  1) The basement air becomes mixed with the upstairs
air, which dilutes the radon.  2) The increased depressurization of the
basement can increase the amount of soil gas, and thus radon, flowing into
the basement, increasing the indoor radon concentration.  3) The increased
depressurization of the basement can increase the amount of outdoor air
flowing  into the basement, diluting the indoor radon concentration.  The
difference in the leakiness between the substructure and soil gas compared
to that of the substructure and the outdoors determines whether process 2 or
3 above will dominate, and thus whether the basement radon concentration
will be enhanced or diminished.  Along with the increased basement
depressurization during the initial combustion stage of heater use, the
second graph shows an increase in the basement infiltration of about a
factor of 1.5 to 2.0.  The basement infiltration is the sum of the
infiltration from the outdoors plus the infiltration from the soil gas.
There is a way to make the second of these terms go to zero, and thus obtain
the relative magnitudes of each of these two terms in the unperturbed case.
The perturbation which can be applied is a subslab ventilation system.

     With a subslab ventilation (SSV) system operating and effectively
reducing the indoor radon levels to below 4 pCi/L, the basement infiltration
from the soil gas is negligible.  The total basement infiltration would then


consist only of the contribution from the outdoors to the basement.  It is
possible that the SSV system can cause increased air to flow from the
basement either out through porous hollow block walls or by some other
mechanism out of the basement into the subslab and out the SSV system.
Consequently, this could increase the basement infiltration from the
outdoors.  Comparing the basement infiltration with and without SSV in use
will still give information on the difference between the infiltration from
the soil gas versus the outdoor air, since any increase in outdoor to
basement infiltration due to the SSV operation would be more of a constant
source rather than sharp changes as observed when the combustion heater
comes on.  Also, initial analysis does not show any significant shift in the
baseline for the basement infiltration when compared to conditions without
the SSV system operating.

     Figure 6 is a plot of the same parameters as in Figure 5, for four days
when the SSV system was operating, subsequent to the days plotted in Figure
5.  The radon concentrations dropped to well below 4 pCi/L, indicating the
SSV system was effective.  (Any measurement of radon below 1 pCi/L is within
the error limits of the detector).  The bottom graph shows that the subslab
air is depressurized relative to the basement air by about 13 Pa, due to
operation of the SSV system.  The large increase in the basement
infiltration at day 59.6 is due to the homeowner airing the basement.  The
average basement infiltration during the initial use of the oil combustion
system each day is 0.33 ACH for days 50-58 (Figure 5) and 0.28 for days 58-
62 (Figure 6).  The difference between these numbers suggests approximately
0.05 ACH infiltrates the basement from the soil gas during the combustion
phase of heater use, when the SSV system is not operating.  Although this
analysis is preliminary and trends are suggested, future more controlled
experiments are needed.

     No significant change in the baseline for the basement infiltration is
observed in this preliminary analysis, any overall decrease due to stopping
infiltration from the soil gas may have been compensated by increased
infiltration from outdoor air due to any air flow from the basement during
SSV system operation.  Leaving that for future more detailed analysis, the
data here suggest that in house 5 (the tightest house in the 7 study homes)
between 1/6 and 1/4 of the total infiltration into the basement is from the
soil gas when the SSV system is not in operation.

     Figure 6a shows the radon concentration in the basement, in one
location of the inner hollow block wall, and in the subslab gas under the
center of the slab during February 20 through March 2 (Julian day 51-61, as
shown in Figures 5 and 6).  It is interesting how much higher the wall
concentration is than the subslab concentration; which was consistent over
time in these two specific locations.  We did not find any other wall
location in this house which gave readings this high.  The wall faces east
and is not adjacent to a slab on grade.  (Note that hollow block walls
between a basement and a slab are often the hottest wall in a given
structure,  due to the slab trapping soil gas.)  The wall radon shows some of
the daily periodicity displayed by the basement radon concentration and, to
a lesser extent, so does the subslab radon concentration.  The wall has
better air flow communication than the subslab with the basement air due to


the very porous nature of the cinder (or concrete) hollow block walls.  This
points out the role of porous walls in soil gas entry.

     The perimeter drain seal shown in the insert in Figure 6a is an
effective way to close perimeter drains, while still allowing the SSV system
to communicate with the air in the hollow walls.   This is demonstrated on
February 26^ when the SSV system is turned on and all the radon
concentrations drastically drop.  In particular it is interesting how the
wall radon level actually drops lower then the subslab level implying more
effective ventilation of the walls than the center of the subslab area.  The
two SSV penetrations into the subslab in this house were located opposite
and adjacent to the wall where the radon concentration was measured, and
about equidistant from both subslab and wall radon monitoring locations.

     Another way to look at the data is to average the different parameters
over time periods that the time-integrating perfluorocarbon tracer gases
were deployed in each house (Figures 7-9) .   The perfluorocarbon tracer (PFT)
gas system measures average air flow rates in multizone buildings.  This
technique measures both infiltration and interzone air flow rates using
passive sources and samplers.

     Each of the seven research houses has been monitored with PFT systems
since the instrumentation packages were installed at the end of October,
1986.  The PFT measurements have been made over typically two week periods
uninterrupted (except for short time periods during mitigation installation)
from the time of installation until late spring to mid-summer, 1986.
Figures 7 and 9 extend through May 15th and Figure 8 extends to July 29th.
The final calibrations for the PFT technique have been applied to the
computation of the air flow rates for these houses.

     The method for looking at the PFT data with the other parameters
consists of averaging the continuously logged parameters over each time
period that the PFT's were active in each house, (which varied slightly
between each house).  Figures 7-9 show this averaged data for homes  1, 5,
and 2 (the control house), taking into account the specific PFT time periods
for each home.  The top box in each figure plots the radon concentrations  in
the basement and upstairs.  The second box displays the basement air
infiltration rate (solid line) and the radon source strength  (broken line).
The third box shows the three logged temperatures at each house: basement,
upstairs and outside.  The fourth box plots the differential pressures
between the basement and the outdoors, subslab, and upstairs  (as in Figures
5  and 6) .  The points on each line represent the average of that parameter
using the given PFT time period.  The lines across the top of the upper box
on each of figures show each PFT time period, which is specific for each
house.  Shown on the abscissa of the lowest box are the Julian dates.

     The seasonal trends are evident, with the outdoor minimum temperature
occurring in late January, lowered humidity in the winter, and increased
HVAC  usage in the winter (the last two parameters are not shown in these
graphs).  The installation of the mitigation systems in all but the control
house (#2) is evident by the decreased levels of radon and larger basement -
subslab pressure differences.


     The radon source strength displayed in the second box is obtained by
assuming the radon behaves similarly to the PFT tracer gas.  The
relationship between the average emission rate (or source strength) of the
tracer gas and the average tracer gas concentration is given by:

     Source (PFT in basement) - Average Concentration (PFT in basement) * K,

where K - a function of all of the air flows in the building.  In the PFT
experiments,  the source term is known and the average concentration is
measured.  The value of K can then be computed and used in the same
equation, with radon source and average concentration replacing the PFT
terms.   Knowing the average concentration of radon in the basement from
averaging the Wrenn chamber data, i.e., the top box on the figure, the radon
source strength can then be estimated.

     Figure 9 displays the radon source rate into the basement for House #2,
(the control house, which was not be mitigated until July, 1987) which shows
a seasonal trend with a strong winter peak.  However, since both the radon
source rate and basement infiltration rate (the major determinant of K)
increase during the winter, the radon concentration does not have a large
winter peak.   In fact, there is not a strong seasonal component in the radon
concentration at all.  House #1 (Figure 7) shows behavior similar to House
#2 (Figure 9) for the basement air infiltration rate.  Instead of a seasonal
dependance, the radon source strength for House #1 decreases and remains low
after mitigation.  This indicates that the reduced radon levels in the
basement are due to decreased source rates brought about by mitigation and
not due to increased infiltration levels.

     Figures 7 and 8 display some interesting behavior.  Houses 1 and 5 are
both ranch style homes of about the same size, and their initial, pre-
mitigation radon concentrations were similar.  The basement infiltration in
house 1 is much larger than that in house 5, however, and  along with the
increased infiltration in house 1 is a larger radon source strength.  Recall
the above discussion about the two terms which make up the total basement
infiltration, i.e., the infiltration from the soil gas and the infiltration
from the outdoor air.  During SSV operation the infiltration from the soil
gas should go to zero.  The time point when the SSV system becomes operable
coincides with the basement - subslab pressure difference becoming negative.
The radon source strengths (and radon concentrations) drop dramatically in
both houses during SSV operation.  The basement infiltration in house 1
remains high, while in house 5 it is significantly reduced during SSV
operation.  This implies that the fraction of air infiltrating the basement
from the soil gas is much less of the total basement infiltration in house  1
compared to house 5.  It could be possible that the total flow of soil gas
infiltrating each basement is similar, but that in the leaky house 1 this
flow is a much smaller percentage of the total basement infiltration.  If
this were the case, the radon concentration in the soil gas would have to be
higher in house 1 to give similar initial basement radon concentrations.

     We know from the Piedmont data, and other studies, that radon
concentrations can vary diurnally by as much as a factor of two due to


environmental effects.  Homeowner interaction with the house can increase
this variation much more due to window and door openings and closings.  This
variation causes a large uncertainty in the use of grab samples to determine
radon concentrations.   To better quantify the magnitude of this uncertainty
the 24-hour average of both the basement and upstairs radon concentrations
has been calculated in the seven Princeton/ORNL research homes.  Figures 10-
15 show these 24-hour averages during the pre-mitigation time period of
October through December, 1986.  All of the data points from each half hour
during this three month period are averaged and plotted as 48 points in the
24 hour day.  The line inside each box is the median of the data, and the
box contains the inner 50% of the data.  The lines which extend out from
each side of the box extend to the extremes of the data or 1.5 times the
distance from the median line to the edge of the box.  The starred values
are the outliers, points that lie beyond the above definition.

     Figure 10 displays the averaged 24 hour basement radon concentration
for the very periodic house 5 discussed above.  Figure 11 shows the heater
use and Figure 12 shows the upstairs radon concentration.  The coupling
between these 3 parameters is obvious (as discussed above).  When the heater
comes on the basement radon is reduced and the upstairs radon increases by
about 10 pCi/L, on the average.  Figures 13 through 15 are similar graphs
for house 3 in the study.  Neither house 3, nor any of the other homes in
the study showed the same periodicity as house 5, although some of the other
homes displayed a somewhat periodic nature in one or more of the other
parameters  (see Figure 15 for house 3 HVAC use) .   One of the more striking
aspects of  the plots for house 3 and the other 5 homes shown is the constant
nature of the median and inner 50% of the data on radon concentrations over
the 24 hour period.  For high indoor radon concentrations, a grab sample
will give a reasonable indication of the magnitude of the indoor radon
concentration (as long as the homeowner has not been airing the house) .  For
low indoor radon concentrations, grab sampling is not a useful diagnostic
tool because of the associated error.

               House 2  Radon Averages

                  (2 day) - (4 day) Averages

                          Julian Date
                                                     PIT/CEF.S RN87

                   Basement  Radon  Levels

                              No  Rainfall
                  Days in Average

                   353 - 357

                   353 - 356

                   353 - 355
               Avg Rn H5

                65 pCi/1


                                               House 5

                                               House 6
      Figure 3

                           Julian Date
                                                              FU/CF.KS RNR7

              Basement Radon Levels
                  House 7, Rainfall Period
                       Day9 in Avaraga
                       324 - 328
                       324 - 327
                       324 - 326
                        Avg Rn Laval
                        33 pCl/L
  Figure 4
Julian Date

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     Figure 5
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                                                                 PU/CEES RN87

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                                    	  - Upstairs  Rn
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                                Julian Data


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                                                                       150 |
                                                                       100 £

      Figure 6
                                        - Bsmnt-Subslab
                                                                    PL'/GEES RN87

               House 5 Radon Levels
                                            DRAIN SEAL
  Feb 20
    FtRure 6n
Feb 22
Feb 24     Feb 26
   Date, 1987
Feb 28     Mar 2

      PU/CEES RNR75

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              — Rn sourcQ strength
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                                              —  - Outdoor  T

     300   320   340   360    15    35    55    75    95    115
                               Julian Data
      - -  Bsmnt-Upstairs
      Figure 7
                                   — —Bsmnt-Subslab
                                                              PU/CEES RN87

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                                     -- Rn  source  strength
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                                                                     - 5
                                                                      4  8
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      300  325  350  375  400  425  450  475  500  525  550  575  600
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     Figure 8
                                                               PU/CEES RN87

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           Basement T
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       300   320   340   360
                               380   400   420
                                  Julian Data
440   460   480   500
      Figure 9
           Bsmnt,-Ups to i rs
                                        — Bsmnt-Subslob
                                                             PU/CEES RN87

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                Military Time of Day

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                         8    10   12  14   16   18  20   22   24
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                                                      PU/CEES RN87

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      House 3

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Figure 14
8   10   12  14   16   18   20   22  24
                     Military Time of Day

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                                                  PU/CEES RN87

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                                                       PU/CEES RNS?

                       RADON DIAGNOSTICS MASTER LIST

     The following is a list of diagnostic techniques that have been used
for determining the existence and extent of a radon problem.   What type of
information and to what extent each of these techniques have  been useful
will not be discussed here.
Phase 1.  Initial Problem Assessment Diagnostics.

     The following diagnostic techniques can be used for characterizing
either existing structures and their sites,  or new construction sites.

     a.  Mobile radiological van for radiation scans both outdoors
     and indoors.

     b.  Mapping of soil gas radon concentrations.

     c.  Mapping of soil permeability.

     The following diagnostic techniques can be used for characterizing
existing structures.

     a.  Visual inspection of structure with completion of questionnaire on
building and house occupancy characteristics.

     b.  Determine radon concentrations in one or many zones within the
structure.   Many techniques are available for doing this such as grab
samples, carbon cannisters or alpha track for integrated samples,  continuous
monitors,  working level monitors.

Phase 2.  Pre-mitigation Diagnostics.

     a.  Natural condition grab sample in each zone and in holes drilled
into the subslab,  into the hollow block walls if they exist, or through any
other existing membrane suspected as a radon source.

     b.  Repeat a. under mechanical -10 Pa depressurization using a blower

     c.  Blower door test of the whole house or parts of house where
possible or interesting, to evaluate building envelope tightness.

     d.  IR scan of each room, to evaluate building envelope tightness.

     e.  Basement/subslab and basement/wall communications using  single or
variable speed motor to pressurize or depressurize the subslab area.  Check
pressure differentials between the basement and subslab on walls  through the
test holes and check air velocity through the test holes to determine
communication from one point to another.

     f.   Check pressure differentials between the basement/subslab and
basement/upstairs as appliances (dryers, exhaust fans, furnace fans, etc.)
are cycled on and off.

     g.   Tracer gas measurements used to evaluate air exhange rates and
flows between zones.
Phase 3.  Mitigation Installation Diagnostics.

     a.  Tracer gas measurements to determine leakage or backdraft of
exhaus t.

     b.  Adjust dampers for balanced air flow within the mitigation system.

     c.  Check the balance by measuring pressure differentials and the
velocities at key points in the mitigation system.

     d.  Integrity check of any building envelope components penetrated by
mitigation system.
Phase 4.  Post-Mitigation Diagnostics.
     a.  Determine radon concentrations in different zones in the building.

     b.  Determine fan speed required for efficient radon removal, consider
         energy aspects.

     c.  Check furnace draft for air flow direction, to insure that
 combustion products are exiting properly.


 These references have been supplied by Dr.  Allan  Tanner.

      References on Radon in Soil Gas,  Diffusion,  and Emanating Power

      The  following have been selected from among about  400 references.
 Preference has  been given  to  recent references that are  particularly
 relevant to radon migration to a structure foundation and to the variations
 of radon  in soil gas.—A. B.  Tanner,  U. S.  Geological Survey

 Akerblom, G., P. Andersson,  and B.  Clavensjo, 1984
 Soil  gas  radon—a source for indoor radon daughters:
 Radiation Protection Dosimetry,  v.  7,  no. 1-4, p. 49-54

 Xkerblom, Gustav, 1986
 Investigation and mapping of radon risk areas:
 Lulea, Sweden: Swedish Geological Co., Rept.  IRAP 86036,  15 p. [To  be
  pub,  in Geol. Survey Norway Special Papers]

 Barretto, P[aulo] M. C.,  1975
 Radon-222 emanation characteristics of  rocks  and minerals, in Radon  in
  Uranium Mining:
 Vienna,  Internat. Atomic Energy Agency STI/PUB/391, p, 129-150

 Bulashevich, Yu, P., and R.  K.  Khayritdinov, 1959
 K teorii  diffuzii emanatsii  v poristykh sredakh [On the theory of diffusion
  of  emanations in porous media]:
 Akad. Nauk SSSR Izvestiya, ser.  Geofiz., no. 12,  p. 1787-1792
 Geophys. Abstracts no, 181-408

 Clements, William E. and Marvin H.  Wilkening, 1974
 Atmospheric pressure effects  on radon-222 transport across  the Earth-air
 Jour. Geophys. Research,  v.  79,  no. 33, p.  5025-5029

 Colle, R., R.  J. Rubin,  L. I. Knab, and J.  M. R.  Hutchinson,  1981
 Radon Transport Through and Exhalation from Building Materials; A Review
  and Assessment:
 U. S, National Bur.  Standards Tech. Note 1139, 101 p. [Washington, GPO]

 Culot, Michel V. J., Hilding  G.  Olson,  and  Keith J. Schiager, 1976
 Effective diffusion coefficient  of  radon in concrete, theory and method
  for field measurements:
 Health Physics,  v.  30, no. 3, p.  263-270

 Eaton, R. S.,  and A. G. Scott,  1984
 Understanding radon transport into  houses:
Radiation Protection Dosimetry,  v.  7,  no. 1-4, p. 251-253

 Barley,  Naomi H., and Terence B. Terilli, 1986
Source term apportionment techniques for  radon, in Indoor Radon, APCA
  Internat.  Specialty Conf. on Indoor  Radon,  Philadelphia, Pa.,  24-26
  February 1986, Proc.;
Pittsburgh,  Pa., Air Pollution Control Assoc. Pub. SP-54,  p.  13-24


Hesselbom,  Ake,  1984
Radon  in soil gas: A study of methods and instruments for determining
  radon concentrations in the ground:
Uppsala, Sveriges geologiska undersokning, ser.  C, no. 803, p. 1-58  [1985]

Jeter,  Hewitt W., J. David Martin, and Donald F. Schutz,  1977
The migration of gaseous radionuclides through soil overlying a uranium
  deposit:  a modeling  study:
U.S. Dept.  of Energy Rept, GJBX-67: 44 p.

Kapustin, 0, A.,  and K. B. Zaborenko, 1978
K teorii emanatsionnogo metoda:
Radiokhimiya,  v, 20,  no.  2, p. 276-283; translated into  English as  Theory
  of the emanation method:
Soviet Radiochemistry,  v.  20, no. 2, p, 235-242
Chem.  Abstracts 88:197876m

Kraner, Hofaart W,, Gerald L. Schroeder, and Robley D.  Evans,  1964
Measurements of the effects of  atmospheric variables on  radon-222 flux
  and  soil gas concentrations,  in Adams,  John A.  S.,  and Lewder, Wayne
  M. eds.,  The Natural Radiation Environment:
Chicago, Chicago Univ.  Press: p, 191-215

Lindmark, A., and B. Rosen, 1985
Radon in soil gas—exhalation tests and in situ measurements:
Science of the Total Environment, v. 45, p,  397-404

Makofske, William J,,  and Michael R. Edelstein,  eds.,  1987
Radon and the Environment, Conference Proceedinas,  Mahwah,  N. J.,  Mav
  8-10, 1986:
Mahwah,  N. J., Ramapo College of New Jersey, Inst, for Environmental
  Studies,  470 p.

Megumi, Kazuko and Tetsuo Mamuro, 1974
Emanation and exhalation  of radon and thoron gases from soil  particles;
Jour.  Geophys.  Research,  v. 79, no. 23, p. 3357-3360

Mochizuki,  Sadamu, and Toshio Sekikawa, 1980
Radon-222  exhalation and its variation in soil air,  in Gesell,  Thomas
  F.,  and Wayne M. Lewder, eds., Natural Radiation Environment III:
Springfield, VA, NTIS,  U.  S.  Dept.  Energy Rept. CONF-780422, Vol.  1,
  p. 105-116

Nazaroff,  W. W. , H.  Feustel,  A. V.  Nero,  K.  L.  Revzan,  D.  T.  Grimsrud,
  M. A. Essling,  and R. E. Toohey, 1985
Radon transport into a detached one-story house  with  a basement:
Atmospheric Environment,  v. 19, no, 1, p. 31-46

Nero,  A.  V,, R.  G. Sextro, S, M. Doyle, B.  A. Moed,  W, W.  Nazaroff, K,  L.
  Revzan, and M.  B. Schwehr, 1985
Characterizing the sources, range, and environmental influences of  radon-
  222  and its decay products:
Science of the Total Environment, v. 45, p.  233-244

Nielson, K. K., V. C. Rogers, and G.  W.  Gee,  1984
Diffusion of radon through soils: a pore distribution model:
Soil Sci. Soc. America Jour., v. 48,  no. 3,  p.  482-487

Rogers, V. C., K. K. Nielson, and D.  R.  Kalkwarf,  1984
Radon Attenuation Handbook for Uranium Mill  Tailings  Cover Design:
U. S. Nuclear Regulatory Commiss. Rept.  NUREG/CR-3533, 85 p.

Rubin, R. M., 1978
Literature Survey on Radon Distribution in Soil and Air; Final Report:
U. S. Dept. Energy Rept. GJBX-110(80), 63 p.

Rudakov, V. P., 1985
K voprosu o prirode sezonnykh variatsiy podpochvennogo radona;
Geokhimiya, no. 7, p. 1055-1058; in English  translation, 1986
Nature of the seasonal variations in  subsoil radon:
Geochemistry Internat.,  v, 23, no. 1,  p. 133-136

Sachs, H. M,, T. L. Hernandez, and J,  W. Ring,  1982
Regional geology and radon variability in buildings:
Environment Internat., v. 8,  no. 1-6,  p. 97-103

Schery, S. D., and D. H. Gaeddert, 1982
Measurements of  the effect  of cyclic  atmospheric  pressure variation on
  the flux of 222j^ from the soil:
Geophys. Research Letters, v. 9, no.  8,  p. 835-838

Schery, S. D., D. H. Gaeddert, and M.  H. Wilkening, 1984
Factors affecting exhalation of radon from a gravelly sandy loam:
Jour. Geophys. Research, v. 89, no. D5,  p. 7299-7309.

Schery, S. D., and D. Siegel, 1986
The role of channels in the transport of radon  from the soil:
Jour. Geophys. Research, v. 91, no. B12, p.  12,366-12,374

Schmied, Hannes, 1985
Combined stack effect in houses and  eskers  explaining transients in radon
Science of the Total Environment, v.  45, p.  195-201

Sextro, R. G., B.  A. Moed, W.  W. Nazaroff, K. L. Revzan,  and A.  V.  Nero,
Investigations of  soil as  a source of  indoor radon,  in Hopke, Philip
  K., ed.,  Radon and Its Decay Products; Occurrence, Properties, and
  Health Effects:
Washington, Am.  Chem. Soc. Symposium  Ser.  331,  p.  10-29

Soonawala, N. M.,  and W. M. Telford,  1980
Movement of radon in overburden:
Geophysics, v. 45, no. 8, p.  1297-1315

Stieff,  L.  R.,  C. B. Stieff, and R. A. Nelson,  1987
Field measurements of  in situ 222Rn concentrations  in soil based on the
prompt decay of the 214gi  counting rate:
Nuclear Geophysics [Internat. Jour. Applied Radiation  Isotopes, Pt.  E.],
  v. 1,  no. 2,  p, 183-195

Taipale, T. T.,  and K. Winqvist, 1985
Seasonal variations in soil gas radon concentration:
Science of  the  Total Environment, v. 45, p.  121-126

Tanner,  Allan B., 1980
Radon migration in the ground: a supplementary review, .in Gesell, Thomas
  F., and Wayne M. Lowder, eds., Natural Radiation  Environment III:
Springfield, VA, NTIS, U.  S.  Dept. Energy Rept. CONF-780422,  Vol. 1,
  p. 5-56.

Tanner,  Allan B., in press
Measurement of  radon availability in soil,  _in Georad Conference on Geologic
  Causes of Natural Radionuclide Anomalies,  St.  Louis, Mo., 21-21 April
  1987,  Proc.:
Rolla,  Mo., Missouri Dept. Nat.  Resources,  Div.  Geology and Land Survey

Wilkening,  Marvin H., 1980
Radon transport processes  below the  Earth's surface, in Gesell, Thomas
  F., and Wayne M. Lowder, eds., Natural Radiation  Environment III:
Springfield, VA, NTIS, U.  S.  Dept. Energy Rept. CONF-780422,  Vol. 1,
  p. 90-103, disc., p. 103-104

Wilkening,  Marvin, 1985
Radon transport in soil and its relation to indoor  radioactivity:
Science of  the  Total Environment, v. 45, p.  219-226

Zimens,  K.  E.,  1943
Surface area determinations and diffusion  measurements by means of radio-
  active inert gases.  Part III.  The process of radioactive emission
  from disperse  systems.  Conclusions  pertaining to the evaluation of
  EP (emanating power) measurements  and  the interpretation of  results
  [in German]:
Zeitschr. Physik. Chemie, v. 192, no. 1/2,  p.  1-55  in  English translation,
  East Orange,  New Jersey, Assoc. Tech.  Services, no.  43G7G, 38 p.  [1955]'

              Radon Contributions  from the Mining Industry

Bates, Robert C.,  1977
Rock sealant restricts  falling barometer effect:
Mining Engineering, Dec.  1977, p. 38-39
"These  analyses demonstrate that radon  contamination  resulting from
  a change in barometric  pressure is reduced by a rock [sealant] coating.
  This,  however,  is not the major fact to be kept in  mind.  More impor-
  tant  is  that,  despite the imperfection  in  the coatings,  the  radon
  concentration in the  mine atmosphere  was reduced  through the use of
  coatings by more than 70% from an average of 480  to 140 [pCi/L]."

Bates, Robert C.,  1977
Sealants restrict  barometric pressure effects:
Mining Engineering, 29(12); 38-39

Bates, Robert C.,  1980
Time dependent radon loss from small samples
Health Physics, 39: 799-801
In connection with a study of the effect of moisture on the radon emanation
  coefficient in small  uranium ore.samples,  the question arose  about
  the time needed  to reach a steady-state flux  of radon from a sample
  after  opening of its  sealed storage and counting can.   It was felt
  intuitively that the  time required to reach equilibrium would depend
  on the pore-filling fluid-and the diffusion coefficient.  No evaluation
  of this effect was found in the  literature.   A  previously developed
  analytical code was used  with a cylindrical model 9,2 cm long and
  3.843  cm in radius, 0.2  porosity, 1E-7 cm"2 permeability, 300 K,  and
  pore-fluid viscosity  of 1.8E-4 g/cm-s.   The periods required to  reach
  a steady-state flux were computed to  be 0,25,  1.25,  10.0,  70,0,  and
  >100.0 hours,  respectively,  for diffusion coefficients of 1E-2,  1E-3,
  1E-4,  1E-5, and  1E-6  cm~2/s.

Bates, Robert C.,  and John C. Edwards, 1978
Radon emanation relative to changing  barometric pressure and physical
  constraints,  in Conference en Uranium Mining Technology, Second,  Reno,
  Nev.,  November 13-17, 1978:
Background is given on  the various equations used to describe diffusion
  and convective  flow of radon in porous  media.  Equations developed
  by the Bureau of Mines  for modeling diffusion  and  Darcy flow through
  multilayered porpus media are described briefly and examples of  their
  use are given.  Cases evaluated include overpressurization, underpres-
  surization,  and cyclic pressurization of different-sized ore bodies.
  Another part of the  analysis deals  with the effect of pinholes on
  the effectiveness of  a  radon barrier coating.

Bates, Robert C.,  and John C. Edwards, 1981
The effectiveness  of  overpressure  ventilation:  a mathematical study,
  in Gomez, Manuel, ed.,  Radiation Hazards in Mining: Control, Measurement,
  and Medical Aspects,  International Conference,  Golden,  Colo   October
  4-9, 1981:
Golden,  CO, Colorado School of Mines,  Chap. 24, p.  149-154
Results  are given  of a  mathematical study of overpressurization ventila-
  tion effects in  underground uranium mines.  The mathematics and conputer


  codes  make it possible  to  analyze many facets of transient and steady-
  state radon diffusion with  Darcy flow.  Rapid changes  in radon flux
  occur  after imposing a pressure differential across the model.  Flux
  into the model mine  drops to near zero and then increases to the steady
  state  level, while  the sink flux  increases rapidly and then  drops
  slightly to the steady-state level.  Magnitudes of mine flux decreases
  and  sink flux increases are dependent upon the distance from the mine
  to sink, permeability, and  the amount of overpressure.

Bates, Robert C,,  and  John C. Franklin, 1977
U. S. Bureau of Mines radiation control research,  in Conference on Uranium
  Mining Technology, Reno, Nev., April 25-29, 1977:
Efforts by the Bureau  of Mines to measure and reduce harmful concentrations
  of radioactive gas  in  uranium mines  are discussed.   Equipment  has
  been developed for  simultaneous monitoring of radon and radon daughters,
  temperature, relative  humidity, absolute pressure,  and air  velocity.
  The effects of changes in weather conditions,  ventilation,  and mining
  methods on the mine  atmosphere can therefore be evaluated.   Addition
  of water to the rock substantially increases the radon emanation from
  rock walls.  Control methods being evaluated include overpressurization,
  cyclic  ventilation,  bulkheading, backfilling with tailings, and application
  of sealants to the mine  rock.

Bates, R. C., and R. L.  Rock, 1962
Estimating Daily Exposures of Underground Uranium Miners to Airborne
  Radon-Daughter Products:
U. S. Bur. Mines Rept.  Investigations 6106,  22 p.

Droullard, R. F., T, H.  Davis, E. E. Smith,  and R.  F.  Holub,  1984
Radiation Hazard Test  Facilities at the Denver Research Center:
U. S. Bur. Mines Inf.  Circ. 8965, 22 p.
The Bureau of Mines  has  developed test facilities for use in a research
  program that deals  with  radiation hazards in mining.  This report
  describes the radon  test chamber located at the Denver Research Center
  and the Twilight experimental mine located near Uravan, CO.

Droullard, R. F., and  R. F. Holub, 1977
Continuous Working-Level Measurements Using Alpha or Beta Detectors;
U, S. Bur. Mines Rept.  Investigations 8237,  14 p.
The Bureau of Mines  has investigated techniques  of using  gross alpha
  or beta detectors  to continuously measure working levels.  Both methods
  measure radioactive  particulates collected on  a filter  paper usina
  a constant airflow.  Inherent-err or studies indicate a  value of  about
  +/- 3 percent for  the  gross alpha method and about +/-  8  percent for
  the  beta method in  typical mine atmospheres.   However, the beta method
  avoids problems associated with alpha detectors and is therefore more
  useful.   Applications  of  these continuous working-level detectors
  include work area monitoring of exposure levels  in underground  openinas,
  such as mines and caves,  and calibrating personal dosimeters exposed
  over extended time intervals.

Droullard, R. F., and R. F. Holub, 1985
Continuous Radiation Working-Level Detectors;
U. S. Bur. Mines Inf. Circ. 9029, 20 p.


The  Bureau of Mines  has used gross alpha and gross beta detectors to
  continuously measure  radiation working levels  for a number of years,
  During this time,  improvements have been made  in the  design and  per-
  formance of continuous  working-level  (CWL)  detectors.  This report
  discusses the improved  designs  and some of the  operating principles
  and  applications  of CWL  detectors in the measurement of radon daughter
  products in mines  and dwellings.

Edwards, John C.,  and  Robert C. Bates, 1980
Theoretical evaluation of radon emanation under a variety of conditions:
Health Physics, 39:  263-274

Franklin, JohnC., 1981
Control of radiation hazards in underground  uranium mines, in Gomez.
  Manuel,  ed. , Radiation  Hazards in Mining: Control, Measurement, and
  Medical Aspects,  International  Conference,  Golden,  Colo., October
  4-9,  1981:
Golden, CO, Colorado School of Mines, Chap, 69, p.  441-446

Franklin, J.  C., R.  C, Bates, and J, L.  Habberstad,  1975
Polymeric sealants may provide effective barriers to radon gas in uranium
Engineering Mining Jour., 176(9):  116-118

Franklin, JohnC., and Randall F.  Marquardt,  1976
Continuous radon gas survey of the Twilight Mine:
U. S. Bur.  Mines, Metal-Nonmetal Health and Safety/Health Program, Tech.
  Prog. Rept.  93,  16 p.

Franklin, John C., Thomas 0. Meyer,  and Robert C. Bates, 1977
Barriers for Radon in  Uranium Mines:
U. S. Bur.  Mines Rept. Inv. 8259,  24 p.
Water-based epoxy sealants were examined during a 2-year period to deter-
  mine their effectiveness as barriers to radon release in uranium mines.
  Radon emanation rates  from uranium ore samples were monitored for
  extended periods  in the laboratory  before  and after sealant appli-
  cation.  Reduction  of  radon flux due to the coating of laboratory
  samples  was  approximately  80  percent.  Test chambers  in  a  dormant
  uranium mine were monitored to  determine both short and long-term
  barrier  effectiveness.  These  field studies of  the sealants indicated
  radon flux reductions exceeding  50 percent relatively soon after appli-
  cation and nearly  75 percent about 1 year later.   An unexpected compli-
  cation to early monitoring in the form of a large  radon emanation
  increase, believed due to added  moisture, is discussed.

Franklin, J.  C., T.  0. Meyer, R. W.  McKibbin, and J. C. Kerkering, 1976
A continuous radon survey in an active uranium mine;
Mining Engineering,  30(6): 647-649

Franklin, J.  C., C.  S. Musulin, and R. C. Bates,  1980
Monitoring and control of radon  hazards,  in International Mine Ventila-
  tion Congress, 2d, Reno, Nev,:
Proceedings,  p. 405-411


Franklin,  John C., Lee T. Nazum, and Adare L. Hill, 1975
Polymeric Materials  for Sealing Radon Gas Into the  Walls of Uranium
U, S. Bur. Mines Kept. Investigations 8036,  26 p.
The Bureau of  Mines conducted extensive laboratory and  limited field
  tests to determine whether  a polymeric material  could effectively
  reduce  the emanation rate of radon gas from uranium ore.   In the  labor-
  atory 46  different single-coat materials and 14 two-coat applications
  were tested.  The laboratory tests  showed that up to 100 percent of
  the radon gas  could be sealed into the rock.  Materials tested in
  the laboratory were polyesters, furan resins, epoxies,  latices, and
  totally inorganic coatings.   From the laboratory work six different
  materials were selected for field testing.  The first test was single-
  coat materials  in five static chambers;  the second test used two-coat
  applications in  an  open chamber.   Both tests were  conducted in the
  Dakota  mine at  Grants, N. M.   During the second test,  the emanation
  rate of  radon was reduced up to 62 percent.

Franklin,  J. C., R. J. Zawadski, T.  0.  Meyer, and A.  L.  Hill, 1976
Data-Acquisition System for Radon Monitoring:
U. S. Bur. Mines Rept. Investigations 8100,  19 p.
A data-acquisition system was designed by the Bureau of Mines to monitor
  five detectors  with radon continuously flowing through each.  These
  detectors could  be  monitored up  to  12 times an hour,  but were only
  monitored according to a preset time, thus allowing radon to be moni-
  tored continuously  in a uranium mine.   The counter can be set to moni-
  tor each detector for any period of time up  to 16.5  minutes.  This
  allows  very  low  concentrations to be monitored longer to  reduce statis-
  tical error.  There would be  no upper limit  in radon concentration
  that could be monitored, but there would be a lower limit of 50 pCi/L.
  Each detector  was  calibrated  in the laboratory by the Lucas flask
  method.   Multiple samples were taken at two different concentrations,
  and the correction factors for each detector was determined by a least
  squares fit of  the data.   To verify the calibrations,  a series of
  measurements at several concentrations (300 pCi/L) with  the two-filter
  method  was within 3 percent;  thus,  the total error would  be this dif-
  ference plus the two-filter error.   At high concentrations the coeffi-
  cient of variation  ranged between  2.1 and  9.8 percent  for the five
  different detector units.

Holub, R.  F.,  1984
Turbulent  plateout of radon daughters:
Radiation  Protection Dosimetry,  7(1-4);  155-158
CA 101;99840n

Holub, R.  F.,  and  P. J. Dallimore,  1981
Factors affecting radon transport  and the concentration of radon in
  mines,  In Gomez,  Manuel, ed.,  Radiation Hazards in Mining:  Control,
  Measurement, and Medical Aspects, International Conference  Golden'
  Colo., October 4-9, 1981:
Golden, CO,  Colorado School of  Mines,  Chap.  154, p. 1022-1028.
".. .The laboratory experiments performed involved measurements of diffusion
  and emanation coefficients, porosity and permeability of  representative
  rock samples.  Significant differences have been found when comparing


  the  results of the  laboratory permeability determinations to those
  of the mine determinations.  Considerations of underlying principles,
  however,  suggest  that the diffusion  and emanation  coefficients are
  the  same  in laboratory  and mine.  It was  also found that  moisture
  content plays a dominant  role  in radon transport through rock,.,."

Holub, R. F., and R.  F.  Droullard, 1978
Radon Daughter Mixture  Distributions in Uranium Mine Atmospheres:
U. S. Bur. Mines Rept.  Investigations 8316,  20 p.
The Bureau of Mines  has made  a study of the magnitude of the variations
  of radon daughter mixtures,  with the objective of determining whether
  these variations reflect  the existing physical conditions in uranium
  mine atmospheres  or if  they are merely random or systematic errors.
  To accomplish this, many data have been  plotted using a triangular
  graphing  technique  which  shows that plateout affects  Po-218 more than
  Pb-214 or Bi-214,  and that  it  is impossible to find simple correlations
  between working level ratios,  radon daughter mixtures,  and age.

Holub, R. F., R. F. Droullard, T. B. Borak,  W. C. Inkret, J. G. Morse,
  and J. F. Baxter,  1985
Radon-222 and Rn-222  progeny concentrations measured in an energy-effi-
  cient house equipped  with a heat exchanaer:
Health Physics, 49(2):  267-277

McVey, James R,,  John C. Franklin, and David M, Shaw, 1977
Portable instrument  measures  four ventilation parameters:
Mining Congress Jour.,  63(4):  49-52
A four-parameter measurement  system for accurate determination of relative
  humidity,  temperature,  mine pressure  and ventilation  velocity has
  been developed for  use in  the radon control research of  the U. S. Bureau
  of Mines.   The new  unit is housed  in a 17-by 20- by 8-in. suitcase
  weighing less than 15 pounds.

                         Additional  references:

Hammon, J. G., K.  Ernst, J. R. Guskill, J. C. Newton, and C. J. Morris,
Development and evaluation  of  radon sealants for uranium mines:
Livermore, Calif., Lawrence Livermore Lab., U.  S. Bur. Mines  Contract
  Rept. H0232047,  67  p.

Lindsay, D.  B., G. L. Schroeder, and C. H. Summers, 1981
Polymeric wall sealant test  for  radon control in a uranium mine, in
  Gomez,  Manuel,  ed.,  Radiation Hazards in Mining: Control, Measurement,
  and Medical Aspects,  International Conference, Golden, Colo., October
  4r9,  1981:
Golden, CO,  Colorado School of Mines, Chap.  118, p. 790-793

Schroeder, G. L.,  1977
Falling barometer nullifies rock sealant effectiveness:
Mining Engineering,  29(6):  38-39

Strong,  Kaye P., Desmond M. Levins, and Anthony G. Fane, 1981
Radon diffusion through  uranium tailings and earth  cover,  in Gomez,
  Manuel, ed., Radiation Hazards in Mining: Control, Measurement, and
  Medical Aspects, International Conference,  Golden, Colo.,  October
  4-9,  1981:
Golden,  CO, Colorado School of Mines,  Chap.  107, p. 713-719

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             Washington, DC  20585
 Michael  Osborne             (M.O.)
 US  EPA - IAB  (MD-54)
 RTP,  NC   27711

 Thomas Feake                (T.P.)
 Radon Action  Program
 Office of Radon  Programs
 401 M Street,  SW
 Washington, DC   20460

.Richard Prill              (R.P.)
 Lawrence Berkeley Lab
 1 Cyclotron Road
 Berkeley, CA  94720

 Michael Pyles              (M.P.)
 Radon Monitoring Program
 Dept. of Envir.  Resources
 '1100 Grosser  Road
 Gilbertsville,  PA  19525
 1-800-237-2366 in PA

 John Reese                 (J.R.)
 2 Empire State Plaza
 Albany,  N.Y.   12257

 Mary Reilly                 (M.R.)
 Div. of Housing & Development
 Dept. of Community Affairs
 FCN 805
 Trenton, NJ 08628

                                TECHNICAL REPORT DATA
                          (Please read Instructions on the reverse before completing)
                                                       3. RECIPIENT'S ACCESSION NO.
 Proceedings of the Radon Diagnostics Workshop,
  April 13-14, 1987
              5. REPORT DATE
               June 1989
 David T. Harrje and Lynn M.  Hubbard,  Compilers
                                                       8. PERFORMING ORGANIZATION REPORT NO.
 Princeton University
 Center for Energy and Environmental Studies
 Princeton, New Jersey 08544
                                                       10. PROGRAM ELEMENT NO.
              11. CONTRACT/GRANT NO.
 EPA, Office of Research and Development
 Air and Energy Engineering Research Laboratory
 Research Triangle Park, NC  27711
                Proceedings; 3/87 - 2/88
              14. SPONSORING AGENCY CODE
15.SUPPLEMENTARY NOTES  AEERL project officer is David C.  Sanchez, Mail Drop 54,  919/
              proceec[ings document a two-day radon diagnostics workshop at Prince-
 ton University,  April 13-14, 1987.  The proceedings comprise a consensus of cur-
 rent knowledge on important radon diagnostic techniques and how they may best be
 applied.  That knowledge is summarized,  placing the various radon diagnostic tech-
 niques in perspective.  Diagnostic approaches offer improved evaluations of radon-
 related indoor air quality problems.  An informed solution involves knowledge of the
 building, the building site,  and the interaction of radon sources with the living space.
 The diagnostics are applicable in four phases of the mitigation process: (l) diagnos-
 tics that assess the radon problem; (2) premitigation  diagnostics, from which a
 suitable  mitigation approach must be selected; (3) diagnostics that check  the perfor-
 mance of the radon mitigation solution; and (4) diagnostics that determine if the ra-
 don problem has been solved and that guideline radon concentrations have not been
 exceeded over the different seasonal conditions experienced.
                             KEY WORDS AND DOCUMENT ANALYSIS
                                           b.IDENTIFIERS/OPEN ENDED TERMS
                           c. COSATI Field/Group
 Atmospheric Contamination Control
  Pollution Control
  Stationary Sources
  Indoor Air Quality
  Building Sites
13 M
 Release to Public
                                           19. SECURITY CLASS (This Report)
                                                                    21. NO. OF PAGES
  20. SECURITY CLASS (This page)
                           22. PRICE
EPA Form 2220-1 (9-73)