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Pdtio-1Sot>17
EPA/600/G-3S/002
January 1938
INSTALLATION AND TESTING OF
INDOOR RADON REDUCTION TECHNIQUES
IN 40 EASTERN PENNSYLVANIA HOUSES
by
A. G. Scott
A. Robertson
W. O. Findlay
AMERICAN ATCON INC.
1105 North Market Street
P.O. Box 1347
Wilmington, DE 19899
F.PA Contract 68-02-4203
EPA Project Officer: D. B. Hen3chel
Air and Energv Engineering Research Laboratory
Office of Environmental Engineering and Technology Demonstration
Research Triangle Park, NC 27711
AIR AND ENERGY ENGINEERING RESEARCH LABORATORY
OFrjCE OF RESEAkCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NC 27711
-------
TECHNICAL REPORT OAYA
(fftttt nsd fasBvrnons IDCNTIFICR5/OPEN ENOED TERMS
C. COSA1 i Field/Group I
Pollution
Radon
Residential Buildings
Monitors
Ventilation
Atmospheric Contamination Control
Pollution Control
Stationary Sources
Indoor Air
Soil Gas
13B
07 B
13 M
14G
13A
06K
ie DISTRIBUTION ST AT t WENT
Release to Public
t9 6r.CUWlTY CLASS (Tt-Jt Report)
Unclassified
31 NO or CAGIS
37?
20 SECuaiT V CLASS iThispcttf
Unclassified
3J PRIC6 ' lcr
wzrs/t.rr
SPA Fern 22*0-1 (d-72) 1
-------
NOTICh
This document has been reviewed in accordance with
U.S. Environmental Protection Agency policy and
approved for publication. Mention of trade names
or commercial products does not constitute endorse-
ment or recommendation for use.
ii
-------
ABSTRACT
In 1984 the EPA started the first of several projects to demonstrate that
soil-generated radon concentrations in most housing types could be reduced by
moderate cost methods. A literature survey of previous work in Canada, Sweden,
and the United States identified active soil ventilation as the most promising
method.
In early 1985 the Pennsylvania Department of Environmental Resources
(DER) started a large radon survey in communities on the Reading Prong (a
granite formation) in eastern Pennsylvania, following the discovery of a house
with extremely high radon concentrations greater than 1.2 MBq/ms. Candidate
houseB for this program with elevated radon concentrations in excess of 750
Bq/m3 were selected from this survey. A total of 40 demonstration homes v»ith
representative substructure types Ibasements with concrete block or solid
concrete walls) were chosen from thid group, and mitigation methods selected
and installed from June 1985 to June 1987.
The initial soil ventilation installations achieved large reductions in the radon
concentrations at low coot, but these reductions were not always sustained m
colder weather a»id a number of the s>stem3 were modified over the course of
the project to improve their performance. Air-to-air heat exchangers were
installed in three of the houses. In one house the elevated radon concentration
was caused by high concentrations of dissolved radon in the well v»ater, und a
radon adsorption unit was installed.
Major reductions in radon concentration v>ere realized in all the houses
worked on, with most houses with active soil ventilation systems achieving less
than 150 Bq/niJ (4 pCi/1) on an annual average basis in the living areas.
The labour and material cost for this work was as low hh S500 in a few
houses, and geneiall> rnnged from SI 200 to S2 400, Costs v*en; high as $6 000
to $10 000 in a few houses with unique features, where extensive experimental
work was done.
Ill
-------
CONTENTS
ABSTRACT ill
LIST OF FIGURES vili
LIST OF TABLES ix
ACKNOWLEDGEMENTS x
1. INTRODUCTION 1
2. SUMMARY AND CONCLUSIONS 3
3. OBJECTIVES AND APPROACH 8
3.1. OBJECTIVES 8
3.1.1. Overall Objectives 8
3.1.2. Objectives of Phaoo 1 Testing 10
3.1.3. Objactivca of Phaue 2 Testing 12
3.1.4. Objectives for Phasa 3 Testing IS
3.2. APPROACH 17
3.2.1. Overall Approach 17
3.Z.2. House Selection Procedure 13
3.2.2.1. Phase 1 House Selection 19
3.2.2.2. Phase 2 House Selection 20
3.2.2.3. Phase 3 House Selection 21
4. PROGRAM SCHEDULE 23
4.1. PHASE 1 23
4.2. PHASE 2 23
4.3. PHASE 3 24
5. DESCRIPTION OF ACTIVE SOIL VENTILATION SYSTEMS 25
6. MEASUREMENT PROCEDURES 27
6.1. RADON MEASUREMENT PROCEDURES 27
6.2. MEASUREMENT GOALS 27
6.3. LONG TERM MEASUREMENTS 28
6.3.1. Sampling Procedure 28
6.4. SHORT TERM MEASUREMENTS 29
6.4.1. Sampling Procedure 29
6.5. DIAGNOSTIC TEST PROCEDURES 30
6.5.1. Pre-Mitigation Diagnostics 30
6.5.2. Post-Mitigation Diagnostic? 31
Preceding page blank
-------
7. EXPERIENCE WITH SUB-SI.AB VENTILATION 32
7.1. PHASE 1 - GENERAL 32
7.1.1. Installation Procedure (Phase 1) 32
7.1.2. Piping 34
7.1.3. Floor Patching 35
7.1.4. Fans 35
7.1.5. Problems 36
7.1.6. Evaluation 37
7..1.7. Comments 38
7.2. PHASE 2 - GENERAL 38
7.2.1. New Installation Procedure (Phase 2) 39
7.2.2. Piping 40
7.2.3. Problems 40
7.2.4. Evaluation 40
7.2.5. Comment 43
7.3. PHASE 3 - GENERAL 43
7.3.1. Installation Procedure (Phase 3) 44
7.3.2. Fans 45
7.3.3. Comment 45
7.3.4. Evaluation 46
7.4. OVERALL EVALUATION OF SUB-SLAB VENTILATION 48
8. EXPERIENCE WITH PERIMETER DRAIN VENTILATION 50
8.1. PHASE 1 - GENERAL 50
8.1.1. Installation Procedure (Phase 1) 53
8.1.2. Fans 54
8.1.3. Problems 55
8.1.4. Evaluation 55
8.2. PHASE 2 - GENERAL 56
8.2.1. f-'.w Fan Installation Procedure (Phase 2) 58
8.2.2. Evaluation 58
8.3. OVERALL EVALUATION OF PERIMETER DRAIN VENTILATION 59
9. EXPERIENCE WITH WALL VENTILATION 60
5.1. PHASE 1 - GENERAL 60
9.1.1. Installation Procedure (Phase 1) 62
9.1.2. Fans (Phase 1} 63
9.1.3. Problems 64
9.1.4. Evaluation 64
9.1.5. Comment C5
9.1.6. Expanding Foams Tested 66
9.2. PHASE k - GENERAL 67
9.2.1. Additional Work On Phase 1 Houses During Phase 2 67
9.2.2. Installation Procedure on Additional Phase 2 Houses SB
9.2.3. Problems 69
9.2.4. Evaluation 69
9.3. PHASE 3 - GENERAL 72
9.4. OVERALL EVALUATION OF WALL VENTILATION 72
vi
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10. EXPERIENCE WITH WALL PLUS SUB-SLAB VENTILATION 73
10.1. INTRODUCTION 73
10.2. PHASE 1 - GENERAL 13
10.2.1. Baseboard Duct Installation Procedure 75
10.2.2. Modifications to Er.isting Systems (Individual Pipes) 76
10.2.3. Evaluation 77
10.3. PRASE 2 - GENERAL 78
10.3.1. Installation Procedure 79
10.3.2. Evaluation 80
10.4. PHASE 3 - GENERAL 83
10.4.1. Evaluation 84
10.5. OVERALL EVALUATION OF WALL PLUS SUB-SLAB VENTILATION 84
11. EXPERIENCE WITH HOUSE VENTILATION 86
11.1. PHASE 1 - GENERAL 86
11.1.1. Installation Procedure 86
11.1.2. Evaluation 86
11.2. PHASE 2 - GENERAL 87
11.2.1. Installation Procedure for HRV's 87
11.2.2. Heat Recovery Ventilators 87
11.2.3. Evaluation 88
11.3. THASE 3 - GENERAL 88
11.3.1. Installation Procedure 89
11.3.2. Evaluation 89
11.4. OVERALL EVALUATION OF INCREASED VENTILATION 91
12. EXPERIENCE WITH RADON REMOVAL FROM WELL WATER 93
12.1. PHASE 2 - GENERAL S3
12.1.1. Installation Procedure 93
12.1.2. Evaluation 93
12.2. PHASE 3 - GENERAL 94
12.2.1. Installation Procedure 94
12.2.2. Evaluation 94
12.3. OVERALL EVALUATION OF RADON REMOVAL FROM WATER 95
13. TERRESTRIAL RADIATION MEASUREMENTS 96
13.1. EQUIPMENT 96
13.2. GENERAL 9f.
13.3. VARIATION. WITH DEPTH 9G
13.4. RADON' PRODUCTION RATE 97
13.5. COMMENT 97
14. QUALITY CONTROL AND QUALITY ASSURANCE 99
14.1. QUALITY ASSURANCE l'LAN 59
14.2. TRACK ETCH DETECTORS 99
14.2.1. Calibration Checks 99
11.2.2. Zero Checks 100
vii
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14.2.3. Field Quality Control 100
14.2.4. Completeness J 00
14.2.5. Quality Assurance Objectives and Performance 100
14.3. AB-5 RADON MONITORS 101
14.3.1. Field Quality Control 102
14.3.2. Completeness 103
14.3.3. Quality Assurance Objectives and Performance 103
14.3.4. Problems 104
14.4. SCINTILLATION CELL MEASUREMENTS 104
14.4.1. Scintillation Cell Field Quality Control 105
14.4.2. Completeness 105
14.4.3. Quality Assurance Objectives And Performance 105
14.5. AUDITS 105
14.5.1. EPA Audits 10C
14.5.2. Internal AuditB 106
14.6. RADON MEASUREMENT PROFICIENCY PROGRAM 106
Appendix A SUMMARY TABLES 107
Appendix B PUBLICATIONS 123
Appendix C INDIVIDUAL HOUSE DESCRIPTIONS 125
LIST OF FIGURES
FIGURE 1 TYPICAL SUB-SLAB VENTILATION INSTALLATION 33
FIGURE 2 TYPICAL DRAIN TILE VENTILATION SYSTEM 51
FIGURE 3 TYPICAL DRAIN TILE VENTILATION SYSTEM 52
FIGURE 4 TYPICAL WALL VENTILATION SYSTEM G1
FIGURE 5 TYPICAL "BASEBOARD DUCT" INSTALLATION 74
vlii
-------
LIST OF TABLES
TABLE
1
SUMMARY
OF
RESULTS
FROM RADON MITIGATION
INSTALLATIONS
6
TABLE
2
SUMMARY
OF
MITIGATION SYSTEMS INSTALLED IN PHASE 1
11
TABLE
3
SUMMARY
OF
MITIGATION SYSTEMS INSTALLED IN PHASE 2
13
TABLE
4
SUMMARY
OF
MITIGATION SYSTEMS INSTALLED IN PHASE 3
16
TABLE
5
SUMMARY
OF
PHASE
1
RESULTS WITH SUB-SLAB SUCTION
38
TABLE
6
SUMMARY
OF
PHASE
2
RESULTS WITH SUB-SLAB SUCTION
41
TABLE
7
SUMMARY
OF
PHASE
3
RESULTS WITH SUB-SLAB SUCTION
47
TABLE
8
SUMMARY
OF
PHASE
1
AND 2 RESULTS WITH DRAIN TILE SUCTION 58
TABLE
9
SUMMARY
OF
PHASE
1
RESULTS WITH BLOCK WALL SUCTION
65
TABLE
10
SUMMARY
OF
PHASE
2
RESULTS WITH BLOCK WALL VENTILATION
71
TABLE
It
SUMMARY
OF
PHASE
1
RESULTS ON SUB-SLAB + WALL SUCTION
78
TABLE
12
SUMMARY
OF
PHASE
2
AND 3 RESULTS FOR SUB-SLAB PLUS
81
WALL SUCTION
TABLE
13
SUMMARY
OF
PHASE
2
AND 3 RESULTS WITH HRV's
90
TABLE
A- 1
PENNSYLVANIA DRK MEASUREMENT SUMMARY
108
TABLE
A-2
HOUSES SELECTED FOR STAGE I WOHK
110
TABLE
A-3
PROPOSED AND ACTUAL PHASE 1 TREATMENTS
111
TABLE
A-4
COSTS OF PHASE J M1TIGATIVE WORK
112
TABLE
A-5
NEW HOUSES SELECTED FOR STAGE 2 WORK
113
TABLE
A-6
PROPOSED AND ACTUAL PHASE 2 TREATMENTS
117
TABLE
A-7
COSTS OF PHASE 2 MITIGATIVE WORK
115
TABLE
A-ft
HOUSES SELECTED i- Ai PHASE 3 WORK
116
TABLE
A-9
PROPOSED AND ACTUAL PHASE 3 TREATMENTS
117
TABLE
A-10
COSTS OK STAGE 3 MITIGATIVE WORK
*18
TA15LE
A-) 1
COST OF SMALL SYSTEM MODIFICATIONS AND
FAN CHANGES
119
TABLE
A-12
SUMMARY OF POST MITIGATION ALPHA TRACK
RESULTS
120
TABLE
A-13
SUMMARY OK GAMMA SURVEY RESULTS
121
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ACKNOWLEDGEMENTS
The assistance of the Pennsylvania Department of Environmental Resources it.
identifying the candidate homes for this study is gratefully acknowledged.
Our appreciation is extended to all the homeowners who participated, and
allowed their homes to be used as experimental sites.
x
-------
SECTION 1.
INTRODUCTION
The U.S. Environmental Protection Agency (EPA) is conducting a program
to develop and demonstrate cost effective methods to reduce the concentration
of naturally occurring radon gas inside houses. This program is intended to
investigate a wide range of radon reduction methods in an effort to demonstrate
suitable mitigation approaches for the full range of U.S housing designs,
substructure types, construction methods, geological conditions and initial radon
concentrations).
Thie report describes one project in the overall EPA radon mitigation
program. Specifically, it describes the installation of developmental radon
reduction measures in 40 existing houses with elevated radon concentrations
located in the Reading Prong region of eastern Pennsylvania.
The 40 houses were selected to be representative of the substructure types
common in that region. All of the houses have basements with concrete floor
slabs, sometimerj with an adjoining slab-on-grsde or crawl-space wine. In 30 of
the houcen the basement foundation walla are constructed of hullcw concrete
blocks, and in the remaining 10 houses of poured concrete. The houses had
initial indoor radon concentrations of at least 750 Becquerel par cubic meter
(Bq/m3) equivalent to 20 picoCuries per litre (pCi/L) or 0.1 Working Levei of
radon progeny, as determined by prior measurements conducted by the
Pennsylvania Department of Environmental Resources. Most rnncentrations \.ere
considerably higher, with an initial level of 44,000 Bq/m1 (1,200 pOi/L) in one
house. In all but one house, soil gas was the predominant radon source for the
house. Well water with up to 11.5 KBq/m3 (310,000 pCi/L) was the predominant
source in the remaining house and is an important secondary contributor lr. a
number of other houses. Extensive gamma measurements in and around the
houses gave no indication thot elevated radium concentrations in the building
materials were a significant radon source in any of the houses.
The active soil ventilation technique for radon reduction was selected for
testing in most of the houses. Where soil gas is the predominant radon source,
active soil ventilation offers a moderate *.osL method of achieving the very high
1
-------
levels of reduction (more than 99% in some of these houses) needed to reach the
EPA guideline of 150 Bq/m1. Air-to-air heat exchangers (heat recovery-
ventilators) for increased house ventilation were tested in three of the houses,
where the initial radon level was less severely elevated (close to the 750 Bq/m3
level), and reductions of 75% would be satisfactory. Greater reductions with
ventilators were not considered practical in view of the natural infiltration rates
in these houses. Carbon adsorption systems for radon removal from well water
were tested in two houses.
The work described in this report was conducted by AMERICAN ATCON
INC. of Wilmington, Delaware, with the assistance of ACRES INTERNATIONAL
CORP. of Buffalo, New York, The work was carried out for EPA under Contract
No 68-02—1203.
2
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SECTION 2.
SUMMARY AND CONCLUSIONS
Table 1 summarizes the results from the 40 houses worked on in this
project. For simplicity, only the result achieved by the final reduction system is
shown. Most of the houses had more than one installation during the course of
the project, and some installations were modified several times as testing
proceeded. These different installations and modifications are described generally
in the report, and in detail for eacli house in Appendix C.
The radon measurements reported in Table 1 below are the arithmetic
averages of at least 48 hours of hourly radon measurements both before and
after the mitigation systems was activated.
The following conclusions can be drawn from the work carried out in this
project:-
1. Where perimeter drain tiles are present at the foot of a buried
concrete block foundation wall, suction on this drain should be one of
the first reduction approaches considered because: a) high reductions
are often achieved, as the drain applies suction near the footing v»h-_-re
it is most effective; b) it is generally the least ej«peneive of the active
soil ventilation approaches, and the most practicable for do-it-yourself
installation, and c) where the tiles drain to a point outside the house,
the entire installation can be carried out from outside, offering
advantages in convenience and aesthetics. Unfortunately, perimeter
drain tiles are not always present.
2. Sub-slab suction, using individual exhaust pipes penetrating into the
sub-slHb fill, can be very effective in houses with either hoi«ow-block or
poured concrete foundation walls. Accordingly, it should be considered
as o candidate control approach whenever major reductions are needed.
If the sub-slab permeability iB good, only one or two suction points can
be sufficient. Even if the sub-slab permeabilit> is low, good
performance can be obtained if more suction paints are installed, located
neur the known soil gas entry routes. For example, best results v«ere
3
-------
achieved when one or more suction points are placed near each load-bearing
block vail (including interior as well as perimeter vails). The actual number and
location of suction points required in a given house vill depend upon the nature
and uniformity of the sub-slab permeability, the location of the major soil gas
entry routes relative to the exhaust points, and system design parameters (such
as whether a hole is excavated under the slab where the pipe penetrates, in
order to reduce system pressure loss). It appears, that through proper system
design, sub-slab suction systems can give high reductions even in houses with
limited or poor sub-slab permeability. Testing thi sub-slab permeability before
installation could aid in assessing the extent of the sub-slab system that will be
required in a given houBe.
3. In houses with block foundation walls, ventilation of the
interconnected network of block voids inside the walls alone can give
high radon reductions if there are no major slab-related soil gas entry
routes. However, current results suggest that a well-designed sub-slab
suction system by itself might be expected to treat both slab-and wall-
related entry routes more effectively and less expensively than a wall
\entilation bystein alone. Accordingly, even in block basement houses
with high radon concentrations, it might be vise to consider sub-slab
suction rather thaa vail ventilution. Wall ventilation might sometimes
be required in combination vith sub-slab suction to reduce radon
concentrations in concrete block basement houses with high initial
concentrations to below 150 Bq/mJ (4 pCi/L).
4. With any active soil ventilation technique, it is important to close
major openings in the floor slab and wall so that the suction is
distributed effectively over the basement surfaces. In houses where the
french drain around the slab edge is required to handle water draining
from the wail, the closure must allow water drainage to continue.
Closure of openings in the block vail appears to be less important, but
all major accessible openings in the floor and walls should be closed as
a matter of course. Floor drains connecting to the soil should be
trapped or plugged to prevent soil gas entry. Sumps should be capped
e\i'n if suction ori the sump is not planned.
5. The fans in the satisfactory drain tile and sub-slab \entilation
systems provided about 100 Pa at the suction points it the soil gas flow
4
-------
encountered (typically 20 to 70 L/b). Higher suction fane did not
produce a performance improvement proportional to the increase in
suction.
G. Dilution appears to be the major mechanism in determining the
performance of heat recovery ventilatorB. However, other mechanisms,
such as changes in internal air circulation also play a role, so that
radon reduction on different floors of a given house cannot be
predicted from dilution considerations alone. In houses without forced
air circulation, such as those with hot water or electric resistance heat,
reductions in the average radon concentration of up to 80% in the living
area can be achieved if >t is ventilated directly with a reasonably sized
HRV. Lesser reductions may be found in other parts of the house. One
unresolved issue in selecting a HRV is whether it is cost-effective
relative to a simple fan providing a comparable increase in natural
ventilation without heat recovery.
5
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TABLE 1 SUMMARY OF RESULTS FROM RADON MITIGATION INSTALLATIONS
IN 40 EASTERN PENNSYLVANIA HOUSES
HOUSE FINAL MEAN RADON LEVEL %
NO TYPE* MITIGATION SYSTEM (Bq/ra') REDUCTION
BEFORE AFTER
1
1
Wall + sub-slab pressurization
(baseboard duct)
5
957
185
97
2
1
Wall + sub-slab pressurization
(baseboard duct) + carbon
adsorption on well water
8
806
111
99
3
1
Wall + sub-slab suction
44
585
185
99
4
1
Sub-slab suction
740
111
86
5
1
Wall pressurization
4
070
185
95
6
1
Sub-slab auction
2
220
185
92
7
1
Sub-slab suction +• wall suction
35
376
148
99
8
1
Wall suction
3
256
222
93
9
1
Wall + sub-slab pressurization
(baseboard duct over French drain)
13
320
259
98
10
1
Drain tile suction (exterior)
7
733
259
97
U
1
Wall + sub-slab suction (bat-eboairi
duct over French drain)
2
220
777
65
12
1
Drain tile suction (exterior)
407
111
75
13
1
Subrslab,suet ion f drain tile
suction (exterior)
3
478
74
98
14
I
Wall suction
2
257
37
98
15
1
Drain tile suction (exterior)
666
37
94
16
2
Wall suction
8
880
148
98
17
1
HKV
2
220
1 406
37
18
1
HRV
74
37
50
19
1
Wall suction
1
295
407
G8
20
2
Sub-slab + wall suction, + suction
on sub-slab in crawl space
10
434
148
99
21
1
Sub-slab suction
4
107
111
97
22
3
Sub-slab suction (basement + slab)
1
258
333
74
23
3
Sub-slab suction (basement ~ slab)
3
515
333
97
24
4
Sub-slab suction
1628
333
93
25
4
Sub-slab suction
5
476
296
93
26
1
Drain tile suction (exterior)
3
293
37
99
27
1
Dram tile suction (exterior)
1
554
111
93
28
1
HRV
592
370
38
29
5
Drain tile suction (interior sump)
+ crawl space 1iner/vent
1
739
74
96
30
1
Carbon adsorption on well wuter
1
073
185
83
31
1
Sub-slab suction
17
945
148
99
6
-------
%
JCTK
80
94
99
99
99
97
99
93
97
TAB!,' 1 (CONTINUED)
FlflAij MEAN RADON LEVEL
MITIGATION SYSTEM (Bq/m')
BEFORE AFTER
Sub-slab suction
222
36
Sub-slab suction
3
108
185
Sub-slab suction
25
752
185
Sub-slab suction
6
068
37
Sub-slab suction
(basement + slab)
5
254
74
Sub-slab suction
(basement only)
703
37
Sub-slab suction
13
875
185
Sub-slab suction
888
74
Sub-slab suction
4
181
111
Block basement walls
Block basement walls ~ paved crawl space
Poured concrete basement walls + slab on grade
Poured concrete basement walls
Block basanient walls + unpaved crawl space
7
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SECTION 3.
OBJECTIVES AND APPROACH
The installation of mitigation measures in the 40 houses was conducted in
three separate test phases. The objectives for each phase were determined in
part by the information gained in the prior phases.
3.1. OBJECTIVES
3.1.1. Overall Objectives
This was the initial field project in EPA's current radon mitigation
program. The primary objective was to develop and demonstrate cost-effective
methods to reduce the radon concentrations in existing housing with radon
levels greater than 750 Bq/ms down to the EPA guideline of 150 Bq/m3 (4 pCi/L)
annual average or lower. The methods were to focus on soil gas as the
predominant source of the indoor radon, although testing also addressed well
water as a source. The radon reduction methods were tested in houses vith
substructure type, design and construction details representative of eastern
Pennsylvania (and man) other parts of the country).
Existing houses (rather than new houses in the construction stage) were
selected as the focus of this study because homeowners in existing houses
needed to know that the technology was available *.o ad lress existing radon
problems. New construction will be addressed in otb',r parts of the EPA
program. The Reading Prong region of eastern Pennsylvania was selected as the
test site for because of the large number of homes with high radon
concentrations that had been found there. In fact, it was only three months
after this contract had been awarded in September 1984 that dramaticall>
elevated radon concentrations of 122 kBq/mJ (3,300 pCi/L) were discovered in
one house near Boyertown, PA. It was this house that first alerted the world to
the extremely high and hitherto unsuspected indoor levels that could result from
naturall> occurring radium in the underlying soil and rock. Houses with rador
levels above 750 Bq/m1 were emphasized in the program because a significant,
number of houses with concentrations above that level wore identified sliorLlj
8
-------
after this project got underway. The house substructures representative of the
region were basements with hollow concrete block or poured concrete foundation
walls, sometimes with an adjoinii.g slab-on-grade or crawl-space wing.
Most of the testing in this project focussed on active soil ventilation
techniques i.e. techniques which utilize a fan to draw or force radon-bearing
soil gas away from the house foundation to prevent entry. Based on an initial
literature review phase that examined possible low cost radon mitigation
methods, it appeared that active soil ventilation techniques had the greatest
potential of providing high reductions in soil gas entry rate with practical
systems at reasonable cost, in accordance with the project objective. House
ventilation is another mitigative option; high house ventilation rates can be very
effective at reducing radon levels, but this approach is not practical during cold
weather. One variant of house ventilation, heat recovery ventilators (HRV's),
was tested in three houses with less elevated initial radon concentrations.
Sealing of soil gas entry rcutes into the house is another possible mitigative
approach, but it was not tested here. Prior experience indicated that is rarely
practical or low cost to achieve the high reductions needed here by sealing, due
to the extensive and concealed nature of the entry routes in hollow concrete
block foundations.
The testing attempted to determine how the necessary radon reductions
could be achieved at minimum cost. The object was to ascertain whether "rules
of thumb" might be defined which would enable effective mitigation systems to
be designed and installed in houses of this type with a minimum of pre-
mitigation testing and installation labour. Ideally, the system would be simple
enough that the hojieowners could install it themselves using standard materials,
in which case the system could be truly low-cost - perhaps only a few hundred
dollars. Even if a contractor were required, to carry out the radon mitigation
work, minimizing the pre-installation testing and installation labour requirements
vould still minimize costs.
In view of this objective, the initial installations in the first phase of this
project were made with a deliberate effort to mimmi?e cost3 - only minimal
efforts were made to close slab and wall openings in conjunction with active soil
ventilation feystems. In addition, installation methods were used that a
homeowner could conveniently employ, rather than methods which uould require
the skills and equipment of a general contractor. Where the initial s> t>lem
9
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installed using this least-coat approach did not achieve the needed radon
reductions, more detailed investigations were carried out to find reasons for the
failure. The syBtem was then modified and retested - sometimes more than once
- in an effort to determine how the system would have to be designed to be
successful under the conditions of the particular house. In some cases, the
lessons learned from this modification/retesting indicated that the system could
not be installed as Bimply and inexpensively as had been hoped prior to the
initial installation. In other cases it appeared that, with new knowledge obtained
from the retesting, this type of system could now be designed to be effecti\e in
future houses without an increase in complexity or cost. Modification and
retesting normally continued in a given house either un*-il the house had been
reduced below 150 Bq/mJ (4 pCi/L), or until it became apparent that no further
significant radon reduction could be achieved at reasonable cost by further
modifications to the existing system.
It should be noted that there was no prior experience in radon mitigation
at these radon levels, or tn this type of terrain, when the first phase of the
project began. Many of the active soil ventilation design techniques which are
now accepted as "conventional wisdom" were not developed when this work
began, and, in fact, evolved in part through the experience gained in this
project among others.
The scope of this project was not the development of a fundamental
understanding of why radon enters a house, nor to discover exactly how a given
mitigative system worked. The resources and time available did not permit
detailed and extensive testing. Rather, this project utilized practical scientific
judgement, together with simple tests, in an effort lo quickly and efficiently
demonstrate and develop effective moderate co3t mitigation technology.
3.1.2. Objectives of Phase i Testing
Phase 1 testing focusaed on determining the effectiveness of minimum-cost
active soil ventilotion systems Steps which would increase the cost of the
installation - such as extensive closure of slab and wall openings, or use of
equipment which would require a general contractor, were reduced or avoided.
Radon mitigation installations were carried out in 18 houses, with the
installation in tv.o of these houses being substantially modified during this
phase. Table 2 summarises th" installations. All 18 houses had basements uilh
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hollov-block foundation walls; one had an adjoining paved crawl-space. In 17
houses, the system tested \. •»« an active soil ventilation system; in the
eighteenth (House #18), the system was a variation of house ventilation. Of the
17 soil ventilation systems: 4 (Houses #1 to #4) involved suction on vertical pipes
penetrating the concrete slab (sub-slab suction): 4 (Houses #5 to #8) involved
suction on the void networks inside the hollow-block foundation wall; 2 (Houses
#9 and #11) involved suction on a baseboard duct covering a perimeter (french)
drain and holes drilled into the block wall cavities; 6 (Houses #10, and #12 to
#16) involved suction on exterior drain tiles around the house footings; and 1
(House #17) involved suction on the sub-slab region via a sump in the basement.
The initial sub-slab suction systems in Houses #2 and #3 were modified to
include block wall ventilation as well as sub-slab suction. In all of the active
soil ventilation systems, the fans were operated in suction.
TABLE 2 SUMMARY CF MITIGATION SYSTEMS INSTALLED IN PHASE 1
HOUSE TYPE*
SYSTEM
1
2
2A
3
3A
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
TVo point sub-slab auction.
TWo point sub-slab suction.
Two point sub-slab; one wall ventilated.
One point sub-alab suction.
One point sub-slab + block wall suction.
Two point sub-slab suction.
Block wall suction.
Block wall suction.
Block wall suction.
Block wall suction.
Sub-slab + wall suction (baseboard over french drain).
Drain tile suction (exterior).
Sub-slab + wall suction (baseboard o\er french drain).
Drain cile suction (exterior).
Drain tile suction (exterior?.
Drain tile suction (exterior).
Drain tile suction (exterior).
Drain tile suction (exterior).
Drain tile suction (interior sump).
Forced air house ventilation.
* Type 1 = Block basement walls
2 = Type 1 + paved crawl spece
11
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The results of Phase 1 testing carried out in the summer indicated that:
a) drain tile suction was generally effective even if there was not a
complete loop of drain tile surrounding the house,
b) block wall ventilation could be very effective, but not in all houses,
c) sub-slab suction was not an effective mitigation method, presumably due
both to the common local practice of pouring the basement floor slab
directly on the subsoil without a layer of crushed stone, and low soil
permeability preventing the sub-slab suction from extending beneath the
footings to prevent soil gas entry through the block walls.
.3. Objectives of Phase 2 Testing
As a consequence of these early results, the Phase 2 primary objectives
re:
0 to determine what modifications would be required to the original least-
cost wall ventilation systems to improve performance by decreasing the
wall leakage area. Particular attention was to be given to those houses
where the block voids at the top of basement walls could not be closed
readily due to openings concealed by exterior brick veneer walls, or
fireplace structures.
0 to demonstrate successful wall ventilation systems in additional
"textbook" houses where all major wall openings were accessible, and
could be closed effectively.
0 to demonstrate wall ventilation systems in houses where some major
wall openings were inaccessible.
0 to demonstrate drain tile suction (interior and exterior) in additional
houses with a drain adjacent to each buried wall.
° to determine whether sub-slab suction could be effective in houses
having poured concrete basemeni walls, despite the poor performance in
houses with hollow concrete block basement walls. The poured concrete
wall could not be a radon entry route in these houses.
0 to determine whether HRV's would provide sufficient reduction in radon
concentrations to be a useful mitigation strategy in houses with
moderately elevated rndon levels.
Tnble 3 sum murine s the installations carried out in Phase 2.
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TABLE 3 SUMMARY OF MITIGATION SYSTEMS INSTALLED IN PHASE 2
HOUSE
TYPE SYSTEM
1A
1
Wall + sub-slab suction (baseboard duct over conventional
wall/floor joint)- replaces original sub-slab system.
IB
1
Additional sealing; fans in pressure.
2B
1
Wall + sub-slab suction (baseboard over conventional
wall/floor joint -replaces original sub-slab system.
2C
1
House 2B plus carbon adsorption on well water.
5A
1
Wall suction, pressurization (improved system in House 5).
6A
1
Sub-slab + wall suction (sub-slab ventilation added to
House fi).
7A
1
Wall suction, pressurization (improved system in House 7).
7B
1
Sub-slab system (separatu system in House 7).
7 C
1
Sub-slab + wall suction (^>»Lems 7A and 7B combined).
9A
1
House 9 with improved sub-slab + wall baseboard system.
14A
1
Block wall suction (replaces original system in House 14).
16A
2
Block wall suction (replaces original system in House 16).
17A
1
Heat recosery ventilator (HRV) (replaces original system in
House 17).
18A
1
HRV (replaces original system in House 18).
19
1
Block wall suction.
20
1
Two point sub-slab suction.
20A
1
Five point sub-slab suction (replaces original system
in House 20).
21
1
One point sub-slab suction.
22
3
Four point sub-slab suction in basement only.
23
3
Four point sub-slab suction in basement only.
24
4
Three point sub-slab suction.
25
4
Four point sub-sleb suction.
26
1
Drain tile suction (exterior).
27
1
Drain tile suction (exterior).
28
1
Drain tile suction (interior sump).
29
5
Drain tile suction (interior sump).
29A
5
House 29 with plastic liner over soil in crawl space venting
under liner.
30
1
Carbon adsorption on well water.
*
Tjt*?
1
Block basement walls.
Type
2
Block basement walls + paved crawl spr.ee.
Type
3
Poured concrete habement wnlls + slab on grade.
Type
4
Poured conci-eto baf>«Mnent walls.
Type
5
Block basement, walls + unpaved crawl space.
As Phase 2 proceeded, it became Mppnrent that some of the conclusions
reached at thf end of Phase 1 werp misleading. Irt particular, while wall
ventilation could prevent entry of soil g&a and rac'on through the hollow block
wall, the connection from the walls to the sub-slab space waB generally not good
enough to deal with major slob entry routes. Moremor, sub-nlab suction now
13
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appeared to offer much greater potertial than seemed to be the case in Phase 1.
Sub-slab permeability in many houses was reasonably good, improved installation
methods had been developed, and a suitable low cost, quiet, higher-sucticn fan
suitable for soil ventilation work had been identified.
In addition, as testing proceeded during Phase 2, it also became apparent
that the radon concentration in some houses had been reduced by the soil
ventilation systems to the point where radon in the well water could be
responsible for a significant portion of the residual airborne radon concentration.
Accordingly, additional objectives were added to Phase 2:
0 to reassess sub-slab suction as a mitigation method for basement houses
with block foundation walls.
0 to demonstrate that combined sub-slab plus wall ventilation ("5 surface
treatment") could provide sufficient reductions in complex concrete
block basement houses with high radon concentrations.
0 to demonstrate the effectiveness of carbon adsorption for radon removal
from well water in :
a) a house where soil gas had been the predominant radon source, but
where soil ventilation had now reduced levels to the point where water
could be the major residual source;
b) a house where well water was the predominant radon source.
With these objectives, the Phase 2 program included major modifications to
10 of the Phase 1 houses. In addition, new installations were made in 12
additional houses beyond the original !8, bringing the total number of houses
tested to 30.
Of the 10 Phase 1 houses which were modified, several were houses which
originally had wall ventilation systems. The modifications were intended to
determine what improvements would be required in the original "least-cost"
installations in order to make wall ventilation function effectnely in houses
having major inaccessible wall openings. The improvements tested included :
additional closure of wall openings; additional ventilation pipes in the walls,
adjustment of the piping configuration to reduce pressure losses; additional
and/or higher suction fans; and testing of the fans in pressure as well as
suction. In other houses among the 10, the original Phase 1 sub-slab or drain
tile system was replaced with an upgraded wall ventilation system. In Mouses ffl
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and #2A, the sub-slab system was replaced by a "baseboard duct" wall ventilation
system around the perimeter. In houses #14 and #16, where ventilation of the
partial drain tile loops had been found to be ineffective, the drain tile
ventilation system was replaced by a wall ventilation system.
Other modifications to the Phase 1 installations included: uddition of sub-
slab suction to an original wall ventilation system in order to test 5-surface
treatment; replacement of the initial system with an HRV in Houses #17 and
#18; and installation of a carbon adsorption unit for radon removal or the well
water line in House #2.
In the 12 houses added to the program: a nominally "textbook" well suction
system was tested in 1 house; inte: ior or exterior drain tile suction was installed
in 4; sub-slab suction was installed in 2 with block basements, and in 2 with
poured concrete basements having adjoining slabs; and radon removal by carbon
adsorption from the well water was tested in 1 house.
3.1.4. Objectives for Phase 3 Testing
The objectives for the Phase 3 testing were extensions of those for
Phase 2:
0 to demonstrate the conditions under which sub-slab suction alone v»as a
sufficient treatment for block basement houses. To determine the
conditions under which 5-surface treatment was necessary and to try to
optimize 5-surface treatment.
° to demonstrate Bub-slab ventilation for basement houses with poured
concrete foundation walls.
0 to demonstrate sub-slab ventilation for poured concrete basement houses
with adjoining slabs on grade.
0 to test the effectiveness of an HRV in a house with moderatelj
ele\ated radon concentrations.
To address these objectives, Phase 3 included modifications to (or
replacement of) the mitigation systems in 7 of the Phase 1/Phase 2 houses, pluo
new installations in 10 additional houses, bringing the total number of houses
treated to 40.
Table 4 summarises the installations carried out Phase 3.
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TABLE 4 SUMMARY OF MITIGATION SYSTEMS INSTALLED IN PHASE 3
HOUSE TYPE SYSTEM
4A 1 Six point sub-sLab suction (replaces original in House 4).
6B 1 Three point sub-slab suction (modification of system in
House 6A).
7D 1 Seven point sub-slab suction (improved syatem, sub-slab
component of House 7C).
13A 1 Four point sub-slab suction (second system supplementing the
drain tile system in House 13).
20B 2 Sub-slab in basement + wall suction ~ suction on installed
sub-slab pipe in crawl space (oodifieation of system in
House 20A).
20C 2 Sub-slab suction in basement crawl space alone
(increased sub-slab suction for system in House 20B).
22A 3 Two point sub-slab suction under adjoining slab as well as
basement.
23A 3 Two point sub-slab suction under udjoinins slab as well as
basement.
2RA 1 HRV (replaces original systea in House 28).
31 1 Six point sub-slab suction.
32 1 Six point sub-slab suction.
33 4 One point sub-slab suction.
34 4 Six point sub-slab suction.
35 4 Slx point sub-slab suction.
36 3 Four point sub-slab suction in baservent and two point
beneath adjoining slab.
37 3 Six point sub-slab suction on basement only.
38 1 Two point sub-slab suction,
39 1 Three point sub-slab suction.
40 4 Twenty point sub-slab suction.
* Type 1 Block basement walls
T>pe 2 Block basement walls ~ paved crawl space.
Type 3 Pourrd concrete baseitient walls + slab on Krade.
Type 4 Poured concrete basement walls.
Type 5 Block basement walls + unpaved crawl space.
In 8 houses the prior installations were modified: 3 block basement houses
had improved sub-slab systems (Houses $4A, ?6B, and cl3A); 2 block basement
houses invohed optimization of sub-slab plus wall ventilation (Houses #?C/7D and
#20C); 2 poured concrete bnsements invoKed an improved sub-slab sjstem with
adjoining slab treatment (Houses S22A and #23A); and I involved replacement of
an unsatisfactoi y interior drain tile (sump) suction system with an HRV
(House *28^).
The installations in the 10 now houses included: 4 block basement houses
16
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receiving a sub-slab suction system; and 6 poured concrete basementB (including
2 with an adjoining slab) receiving a sub-slab suction system.
3.2. APPROACH
3.2.1. Overall Approach
To identify candidate houses for inclusion in this testing program, the
Pennsylvania Department of Environmental Resources (DGR) contacted prospective
homeowners prior to each test phase. For the first two phases, DER contacted
all the homeowners regardless of house type, whose houses had been found to
have radon concentrations of 750 Bq/m3 (20 pCi/L) or above based upon DER
measurements. By the time house selection was required for Phase 3, extensive
data on the house characteristics were available in DER's computerized data
base, and so contacts were directed only to homeowners whose houses were
above 750 Bq/ms, and appeared to have both the desired substructure type and
an unfinished basement.
Visits were made to the houses of those homeowners who indicated an
interest in becoming involved in the program. During the visit a visual
inspection of the house was carried out, and the program discussed with the
homeowners. In some cases, limited diagnostic testing was done, such as grab
samples to check radon levels in the house, near soil gas entry routes, and
gamma radiation measurements. The houses were then selected on the basis of
the information gamed on these visits, utilizing the selection criteria described
later.
An agreement between AMERICAN ATCON and the selected homeowners was
signed prior to the start of the work. In this agreement, the homeowners
agreed to make their house available for installation and testing of the
mitigation system. AMERICAN ATCON agreed to install the system at no cost to
the homeowner, and to turn the s> stein over to the homeowner (or, at the
homeowner's option, to remove the system) at the end of a year of testing.
The effectiveness of the s> stem to be installed was not guaranteed.
All the homeowners were promised that their identity, and all data
collected in th<.-r houses, would be kept confidential. Accordingly each house
has been assigned a code number, and the houses are identified by that number
in this report.
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As discussed in Section 3.1, the approach involved initially installing
mitigation systems in Phase 1 on a least-cost basis, and then modifying the
systems as necessary if the initial installation did not provide sufficient radon
reductions. The program included a variety of commercially practicable test or
diagnostic procedures, but could not include extensive fundamental diagnostic
testing.
3.2.2. House Selection Procedure
The contract was awarded in 1984, and at that time there was a limited
number of areas v,here radon measurements had been made on any 6cale. Radon
measurements had been made in Pennsylvania by groups from Princeton
University and Argonne National Laboratory, both of v horn had found levels as
high as 3.7 kBq/ms (100 pCi/L) in some houses. These concentrations were
among the highest measured in the L'SA at that time, and therefore Pennsylvania
looked an attractive site for the stuoj. These groups were contacted in late
1984. As they had agreed to keep their measurements confidential, they could
not supply the names of those people with the highest radon concentrations
directly to AMERICAN ATCON, but they did agree to bend letters to inform
these people of the proposed EPA program to demonstrate low-cost radon
mitigation measures, and ask them if they would be interested in participating in
the program. Neither group received replies to their letters.
In ear'v 1985, the PER started a targe radon survey in the Boyertov»n area
as the result of the accidental discovery in December 1984 of a house v»jth
average radon levels in excess of 122 kBq/m' (3 300 pCi/L). By April 1985,
approximately 150 houses with at least one survey measurement greater than
0.1 Wl, or 750 Bq/'mJ (20 pCi/L) radon had been identified in the Boyertown
area. Subsequently the survey area was extended to cover the Whole cif the
Reading Prong which extends from Reading to Eastern in Pt-nnsj 1\ania. By mid
198G over 25 000 houses had been surveyed bj the DER, providing an
unparalleled data ba^e of measurements and house descriptions. A summary of
the results of nil the [)TR measurements in the houses selected for the program
is given in Table A-l in Appendix A.
18
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3.2.2.1. Phase 1 House Selection
The DER was contacted in early 1985, and were willing to assist in finding
persons interested in participating in the firBt phase of this program. As they
had promised the homeowners the measurements would remain confidential they
could not release the names, but they did agree to send a letter to each of the
homeowners with concentrations in excess of 750 Bq/ms (20 pCi/L) to inform
them of the EPA program, and provided them with a form letter to return to
AMERICAN ATCON if they wished to be considered for participation in the
program. This letter also gave permission for DER to release the survey
information.
Replies were received from 71 homeouners by early April 1985, a number
far in excess of the 18 needed for the first stage of this program. As only a
fraction of the houses could be selected, it was felt that the fairest selection
procedure would be to visit and inspect all the houses, and only then make
decisions on their suitability for the program. In the last two weeks of May, 69
of these houses were visited. Each house was photographed, received a brief
visual inspection, and notes were taken on the construction and any other details
that might affect the mitigation work.
The criteria used to select 18 houses from the 63 were:
° The homeowners must be willing to participate in a development
program such as this.
° The house must be accessible during the work day.
° The house should have a basement with a hollow concrete bloc!r walls,
because this was most common substructure type among the houses
visited.
° The houses should have the features needed for the testing of the
intended mitigation systems {e.g., some must have dram tiles).
® The house should not be unnecessarily espensive to mitigate. In
particular, houses uith moderate sized unfinished basements were
preferred.
0 The house location should be reasonably convenient to a central
location, and in an area where more than one house with elevated
radon concentrations had been identified.
® The rudori level should be above 750 Bq/m'.
19
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AH of the houses chosen in Phase 1 were within an 10 km radius of
Boyertown. Six of the houses were in the country, eight were in rural
subdivisions noted for high radon levels m their houses, and four were m town
or suburban subdivisions. The houseB were typical of the type of houses built in
the area over the past 40 years.
Table A-2 ehows the locations and initial radon concentration of the houses
selected for Phase 1, Table A-3 shows the work planned and carried out in these
houses, and Table A-4 shows the sum of contractor charges for labour and
materials to carry out the work.
3.2.2.2. Phase 2 House Selection
Ab discussed in Section 3.1.3 above, 10 of the Phase 1 houbes were carried
over into Phase 2, either to modify the initial systems or to install different
ones. In addition, it was desired to select some additional houses.
The criteria used to select the additional houses were basically the same
as those for the Phase I houses. The differences were that, for Phase 2:
0 Basement houses with poured concrete foundation walls were also
considered.
0 Houses where the tops of the concrete block basement walls were
readily accessible so that they could be closed for wall ventilation, in
addition to the other criteria listed above.
By the end of 1985, the DER survey had extended well beyond the original
Boyertown area, and had now identified more than 250 houses over
750 Bq/ms (20 pCi/L). To achieve a greater geographic coverage, and hopefully
to reach a number of different housing types, the DER was requested to send a
letter to the newly identified houses to inform them of the EPA program, and
provide them with u form to indicate if they would be interested m
participating in the program.
Replies v»ere received from about 90 of the 250 homeowners, but there \»as
a considerable overlap with the initial group that had responded to the Phase 1
mailing. The DER had collected details of house construction and layout of all
these houses, so nn initial selection of 27 new candidate houses \*us made froin
their records. Some preference vas given to houses outside the immediate
Boyertown area with concrete basement walls. All houses with exposed eaith n:
the basement or field-.slone basement walls were rejected.
20
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In January and February 1986, candidate sites were visited by the Field
Construction Supervisor who photographed the house and basement, and noted
the construction features that might affect mitigation work. The final selection
of 12 additional houses was made on the basis of th'5; selection criteria described
above. Four of the 12 additional houses were in a rural subdivision 20 km from
Boyertown noted for the high radon levels in the houses, and the remainder were
in the country. Three of the houses were on the same hills as houses selected
in Phase 1. All of the houses were within a 25 kin radius of Boyertcwn.
Table A-5 shows the locations and initial radon concentration in the houses
selected for Phase 2. Table A-6 shows the work planned and carried out in
houses during Phase 2, and Table A-7 shows the sum of contractor charges for
labour and materials to carry out the work.
3.2.2.3. Phase 3 House Selection
Some of the Phase 1/Phase 2 houses were carried over into Phase 3 for
additional work. In addition, it was desired to select additional houses, using
the same solection criteria as for Phase 1 ai.d 2.
By the fall of 1986, the DER survey results had been greatly expanded as
the result of a large alpha-track detector survey focussed on the Reading Prong
region. The measurement results, along with data on the characteristics of the
houses, were in the process of being entered into a computerized data base.
Using a version of the data base that did not allow names or addresses of the
homeowners to be identified, EPA selected 47 previously uncontacted candidate
houses that met the screening criteria of radon level above 750 Bq/m1,
unfinished concrete block or poured concrete basement walls, with or without an
adjoining slab on grade. As before, the DER sent letters to these 47
homeowners, most of whom lived on the northern end of the Reading Prong in
the Allentown - Bethlehem - Easton area.
Of the 47, 23 homeowners responded. These 23 houses were visited in
September 1986 with an EPA group including the Project Manager. Each house
and basement was photographed and sketched, and extensive notes made on
construction details using h standard evaluation form developed by another EPA
project. Notes were also made of details that would affect the choice of
mitigation method. The final selection of 10 additional homes was made on the
basis of the selection criteria.
21
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Table A-8 shows the location and initial radon concentration in the houses
selected for Phase 3. Table A-9 shows the work planned and carried out in
houses during Phase 3, and Table A-10 shows the sum of contractor charges for
labour and materials to carry out the work.
Table A-ll shows the cost of small modifications and fan changes that did
not amount t" a change of installation.
22
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SECTION 4.
PROGRAM SCHEDULE
4.1. PHASE 1
The first phase of this work was carried out in July and August 1985. The
summer months are convenient for outside work, but as the forces that urge
soil gas containing radon into the houses are at their lowest at this time, it is
difficult to tell if the measures installed will be effective in the winter. All but
one of the installations produced major reductions in summer radon
concentrations, so further work was suspended until the winter, when the
system performance could be measured under more challenging conditions.
Short term measurements were made during November and December 1985 in
the Phase 1 houses to confirm that the reductions found in the summer were
still valid. Some of the temporary fan installations were modified to cure
problems with condensed soil gas moisture blocking the ductB in cold weather,
and to increase the Buction. Where concentrations were lo\«, "Track-Etch"
detectors were placed in the house to provide a long term estimate of the radon
concentration. In those places where concentrations had not been reduced, the
system was examined to find tho cause of the reduced performance, and then
modified. Short term measurements were used to judge the value of system
changes. When rudow concentrations had been reduced to low values,
"Track-Etch" detectors wore placed in the homes for confirmation.
4.2. PHASE 2
Sew Phase 2 houses were selected in January and February 1986, and
mitigation systems were installed and evaluated in all of Ihese houses b> the end
of May 1986.
During November and December 1986, most of the exhaust fans on PhKse 1
and 2 houses were changed from 50 or 100 L/tt fnns to 150 1/s plastic body
exhaust fans, and system and performance measurements made to see if the
higher suction or flow made any performance improvement. Where radon
concentrations were low, "Track-Etch" detectors were placed m the house to
provide a long term estimate of the radon concentration.
23
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In those places where concentrations had not been reduced, the system was
eKarnined to find the cause of the reduced performance, and then modified.
Short term measurements were used to judge the value of system changes. When
concentrations were reduced to low values, "Track-Etch" detectors were placed
in the homes for confirmation.
4.3. PHASE 3
New Phase 3 houses were selected in November 1986, and work on these
was conducted between December 1986 and June 1987. Only 150 L/s exhaust
fans were used in these installations. "jome installations were completed after
the end of the heating season, so "Track-Etch" detectors could not be used to
give long-term estimates of the cold weather performance.
21
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SECTION 5.
DESCRIPTION OF ACTIVE SOIL VENTILATION SYSTEMS
Most of the radon reduction installations tested during this project
involved some form of active soil ventilation. Active Boil ventilation was
emphasized because it appeared to be the approach most likely to provide the
very high reductions usually needed in these houses et a reasonable cost.
The general principle or soil ventilation is to change the pressure in the
soil adjacent to the building foundations to divert the radon-bearing soil gas
away from the house before it can enter. When fans are employed to produce
the pressure change, the approach is referred to as active soil ventilation. The
systems can be used to either a) draw suction on the soil around the foundation
to collect the soil gas from the soil and to vent it away from the house; or b)
to blow outdoor air into the soil, creating a "pressure bubble" underneath the
house which forces the radon bearing soil gas away.
Tf an active soil ventilation system is operated with the fan in suction, as
was the case with most of the installations here, it will be effective only if it is
able to maintain soil gas pressura lower than the air pressure inside the house
near oil of the major soil gas entry routes. Under this condition, if there is
any gas movement through those potential entry routes, it should be house air
flowing out rather than soil gas flowing in. If the fan is operated in pressure,
blowing outdoor air into the soil, it will be effective only if it can maintain a
sufficiently high air pressure near the entry routes that soil gas will be forced
away from them. Soil ventilation systems iri pressure also work in pai t by
diluting the soil gaa in the general area of the foundations with outdoor air
before it can enter the house.
In this project, active soil ventilation v»as accomplished in several
different ways.
° Suction on the perimeter drain tiles located beside the footings for
water drainage purposes. The drain tiles can be on the outside of the
footings (in which case they are referred to as an exterior drain), or
inside the footing, under the slab (interior drain tiles). There were no
internal drain tiles in these houses. If the tiles drain to a sump inside
25
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the house, drain tile suction id most conveniently carried out by suction
on the sump.
0 Suction on the region underneath the concrete floor Blab, by inserting
suction pipes vertically downward through the slab from inside the
house.
0 Suction on (or pressurization of) the network of voids inside hollow-
block foundation walls. This was accomplished by inserting individual
ventilation pipes into the void network.
° Suction on both the void space of hollow concrete block walls, and on
the Bub-slab material, by installing a baseboard duct which covers holes
drilled into the wall block cavities and the joint between the floor slab
and the walls.
Figures 1 through 5 present generic illustrations of these types of active
soil ventilation systems. These figures are taken from the second edition of
EPA's "Radon Reduction Techniques for Detached Houses: Technical Guidance".
Most of the installations made under this project differ in some details from
these generic figures. fact, the testing under this project helped lead to
some of the design refinements which are incorporated into these figures from
EPA's guidance document.
26
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SECTION 6.
MEASUREMENT PROCEDURES
6.1. RADON MEASUREMENT PROCEDURES
The performance of the radon reduction systems was determined through
two types of radon measurements in the indoor air. The firBt was short-term
monitoring for 2 to 4 days with Pylon AB-5 radon monitors both before and
after the system was activated. These measurements provided an immediate
indication of the approximate reduction m radon concentration, and whether the
post-mitigation concentrations had been reduced below 150 Bq/m3 (4 pCi/L). The
6econd was a long term measurement over a period of up to three months with
alpha track detectors during the heating season to indicate whether the house
was being reduced below 150 Bq/mJ under worst-case conditions. By comparison
with any alpha-track measurements that the 1>ER might have in9de the previous
winter, these long-term measurements could also indicate the long-term winter-
time reduction in radon concentrations.
"Control houses" were not used in this project. First, there was no
expectation that the variation of radon concentrations m one house chosen
essentially at random would be identical to the variations m another house.
Second, an effective mitigation system reduces radon concentrations to a lo\*
level and Loeps them low. This can be shown readily with real-time radon
concentration measurements, so "controls" are unnecessary 1o determine if a
mitigation ajstem is effective.
6.2. MEASUREMENT GOALS
The goals of the post-mitigntion measurement program were to estimate:
a) the lon& term rwerago rndon concentration with a total
mcfihiiicmcnl uncertainty of less than SO Rq/mJ (2 pCi/L)
b) the short ter>n average radon concentration with a total
inf/iiuremonl uncertainty of less than 10%
c) individual radon concentrations with a total measurement
unci'i ,, nniy of less than 20%
27
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6.3. LONG TERM MEASUREMENTS
The long term average concentration m a house was measured with Track
Ftch detectors, exposed for a minimum of 1 month, and normally for 3 months.
The forces that urge soil gas and radon into a house are nt a maximum in cold
weather, so detectors were exposed in the winter months when the effect of the
mitigntion work might be lowest. The original survey measurements by the DER
wore largely taken in the winter, so their measurements provided a realistic
estimate of pre-mitigation radon concentrations for comparison of the long trrm
concentrations before and after the mitigative work. A summary of all the post
mitigation alphu track results, is given in Table A-12.
6.3,1. Sampling Procedure
The procedure used at the start of the program was to expose detectors in
groups of three in both the basement «nd the living area of the house. The
initial criterion for placement was that the basement detectors should be hung
centrally, and the upstairs detectors should be placed in locations where they
would receive an exposure representative of the occupants.
28
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In the second year of this program the EPA produced a Protocol for Indoor
Measurements, and the sampling location criteria were formalised to agree with
the Protocol.
6.4. SHORT TERM MEASUREMENTS
The short terra variation of radon concentration with time was measured by
a Pylon AB-5 operated as a quasi-continuous radon monitor. An iniernal pump
draws an air sample for 10 minutes each hour into a 285 cm' scintillation cell,
and six consecutive 10 minute counts are made. In this mode the machine can
make consecutive 99 hourly cycles, and the counts are stored internally. The
data is subsequently transferred via the printer interface and a specially designed
parallel to serial converter to the RS-232 port of a portable computer. A BASIC
program sums the counts, and calculates the radon concentration in the sample,
and produces a report. The counts observed in each time period are corrected
for the counts resulting from activity deposited in the cell by previous samples,
so that the actual radon concentration in the sample is calculated.
To prevent small children from tampering with the machine and altering
the settings, each AB-5 is stored and used inside a lockable foam lined
aluminum travel case. Two holes are drilled in the case, one for a sample hose
to bring in the air, the other for the power cord, so that the machine can
operate with the case closed and locked.
6.1.1. Sampling Procedure
The standard procedure was to place the AB-5 in the basement, close the
windows and the stair door to standardise the ventilation rate to some extent,
and measure the radon concentration over the r.e\t 48 hours. A state of
quasi-equilibrium between radon supp'y and remo\ul v»as usually reached in less
than 24 hours. The soil ventilation fan was then turned on or off, depending
on the test being made, and measurements continued for anothe.- -18 hours. The
b> stems normallj develop most of their effect within 24 hours.
The initial criterion for monitor placement was simply that the unit should
not be placed close to known or suspected radon entry routes. The basement
walls are alwajs colder than the basi-ment air, and there are large convection
flows mixing the basement air, so the concentration is relatively uniform
throughout each room in the basement, except near radon entry points. In the
-------
second year of this program (i986) the EPA produced a Protocol for Indoor
Measurements, and the sampling location criterion was formalised to agree with
the protocol. The sampling location was now selected to be at least 50 cm from
the floor or wall, 1.5 m from fireplaces, windows or HVAC vents, 2.5 m from
exterior doors, and away from radon entry routes.
The protocol required that measurements be made at least 50 cm from the
floor, and so the aluminum travel cases were modified. A bulkhead connector
was placed on one end of the handle face of the case, and the AB-5 inlet hose
attached to this on the inside of the case through an in-line filter. A rigid
plastic tube screwed into the connector. When the case stood with the handle
uppermost, the top of the tube was 50 cm from the ground. If the case stood
at right angles to the wall, the sample tube was 50 cm from the wall.
The AB-5 measurements were not intended to be definitive, but to indicate
only whether the raitigative actions taken had significantly reduced the radon
supply rate. The effectiveness would not be determined on the basis of short
term measurements over a few days with an AB-5, but would be based on the
a\ erage concentration over a month or more obtained with multiple "Track Etch"
detectors.
6.5. DIAGNOSTIC TEST PROCEDURES
6.5.1. Pre-Mitigation Diagnostics
The primary types of pre-mitigation diagnostics conducted during this
project were the following.
° Visual sur\ey. This includes inspection of the house to identify
potential soil gas entry routes other than hollow concrete block walls
and joints in the basement floor slab, and for features that would
increase the installation difficulty of particular mitigation systens.
o Gntnma ir.sasurements. These are intended to confirm that building
materials are not a major contributor to indoor radon.
° Well water measurements. These are intended to identify the degree to
which well water is a contributor. These measurements were usually
conducted by DER as pai t of their survey program.
» Sub-slab permeability measurements. In a fev. of the later houses here
sub-slab suction v;is planned, the permeabilit,\ of the matei ial under the
30
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slab wbb determined qualitatively. A high suction industrial vacuum
cleaner was used to draw suction on a 3/8 inch hole drilled through the
slab, while a pressure gauge or a smoke stick was used to determine
whether this suction extended beneath the slab to other test holes
through the slab some distance away.
6.5.2. Post Mitigation Diagnostics
The primary types of post-mi tigation diagnostics conducted during this
project were the following.
° Radon in Air Measurements. The prime indicator that a mitigation
system was operating effectively was the radon concentration in the
basement air. Measurements were made with Pylon semi-continuous
radon monitors for two at least days before and following activation of
any installation or change in a system.
0 Visual inspection. This included inspection of the installation to
ensure that seals were intact and the fan was properly mounted. As
part of this inspection, a smoke stick was used to check the seals in
active soil ventilation systems, and that air flows through potential
entry routes had in fact been reversed by the suction systems. The
smoke stick was also used to visualize the direction of house air flows
during the operation of HRV's.
0 Pressure difference and airflow measurements. The pressure
differentials to atmosphere and the air flow rale in each pipe or duct
of the active soil ventilation systems were measured using a hof film
anemometer. A probe adaptor enables the same instrument to read both
flow and pressure.
° Spot radon concentrations. Grab samples were taken from each pipe in
the active soil ventilation s>stem v»ith a scintillation cell for radon
analysis. Similarly, where soil ventilation systems did not pros ide
sufficient reductions, grab samples v*ere made from enclosed potential
entry routes to assess which routes i>ere not being adc»quatel.s treated.
These grab samples uere taken through holes drilled through Ihe face
of block foundation walls, or from inside temporary plastic enclosures.
31
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SECTION 7.
EXPERIENCE WITH SUB-SLAB VENTILATION
7.1. PHASE 1 - GENERAL
It had been speculated that the radon source in these houses might be the
highly fractured granite bedrock that lay just beneath the basement floors. The
radon concentration would be very high in the thin film of air between rock
surfaces, so a small flow of this "rock gas" could produce high radon levels in
the house. If this was the case, then sub-slab ventilation could be very
effective in reducing the radon inflow by intercepting the flows of "rock gas"
before it could enter the house through openings in the floor.
Sub-slab ventilation had been used at other raitigative projects where the
radon source was local soil. The success rate of sub-slab ventilation there had
been high in houses with solid concrete basement wall3, but it was lees effective
in houses with hollow concrete block basement wails. The voids in the blocks,
and the inevitable small openings in the walls at the footing level provided a
horizontal e.itry path for soil gas containing radon. If the entry route was
almost comt>!'*tely through openings in the floor and the vall/floor joint, as was
the case in basements with solid walls, then sub-slab ventilation could effectively
prevent soil gas entry. But if there was a significant horizontal flow of soil gas
through the block basement walls that could not be diverted and intercepted by
the sub-slab syste the reductions obtained would be much smaller. Although
sub-slab \entilation was not an assured mitigative procedure, the prospects for
success \»ere good, and it would be by far the simplest procedure to install. The
decision was made to start the program by installing sub-slab \ entilation.
An illustration of a tj pi'-al sub-slab ventilation sjstein is shovn m
Figure 1.
7.1.1. Installation Pi ocuduru (Phase 1 )
To ininimiye .¦spallation costs, active soil ventilation sj stems \sith sub-slab
collection were chosen. These sj stems use the coarse stone fill beneath the
floor slab as the collector, and compensate for the flou resistance by using a
smalt electric fan lo pioduce the -uction.
32
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Exhauet (preferably released
above eaves)
S
Outsicta
fan
(optional)
Optional
piping
configuration
Slope horizontal lag
down toward cub-slab
hole
-pAt
To exhaust fan
mounted In attic
or on root
Nets:
1. Cto&lng of major stab openings
(e.g.. major tattling cracks, utility
penstrrtions. gaps at the wall/
floor joint! I* Important.
Sealant
. ".Soil
Sealant
* Slab:,M
Connection to other
suction poinds)
House air through unclosed
settling cracks, cold joints,
utility openings'
t>V is AtW f
V.• tr^'/'iy '» ' yj v* • ; {';• ;V'. :i*. Open hole ••_
•V: -*"• targe as
¦ -.--.reasonably
•» •" '-practical)
FIGURE 1 TYPICAL SUB-SLAB VENTILATION INSTALLATION
33
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In passive systems, where the suction produced by wind and weather forces
is only a few pascal more than the pressure differential between the house and
the soil, a network of pipes would have to be placed under the floor to
effectively utilise this low suction. This v>as considered too disruptive and
expensive, and so pasBive systems were not considered for this program.
Vertical exhaust pipes were placed through the floor uitc the fill layer,
and were located by the rule of thumb that the collection point should be
equidistant from, and not more than 5 m from the external walls. Three of the
Phase 1 houses were rectangular, and required two collection points. To
further reduce costs, in houses #2 and #4, the exhaust pipes were Tee'd to an
indoor collection pipe which lead to a single fan outside the house. The
basement of house #i was extensively finished, so there was no place to run a
central collection pipe. In this case, each exhaust pipe had its own fan.
The basement at house #3 was almost square, and only one central exhaust
location was installed there. In all four houses the exhaust fans were placed
outside in the basement window wells. The windows were removed, the openings
blocked off with plywood, and a flexible exhaust pipe passed through to the fan
on the outside. This was a temporary mounting, and was used to reduce the
amount of work needed to remove the installation if it were unsuccessful.
7.1.2. Piping
The piping used was "4 inch" plastic drain pipe. It was light weight,
readily availaole, and airtight joints could be produced by gluing. The
tradesmen who performed the work were plumbers and used to working with
pipe. Although the pipe itself was always in stock, the number of fittings (Tee's
and elbows) needed caused temporary local shortages, and supplies iiad to be
obtained from every builder's supply store within a ten mile radius.
It was found that air flows in the systems were small enough that the low
resistance to air flow of large pipe was not needed, and much smaller piping
("2 inch" drain pipe) would have b^en sufficient. Smaller piping would be easier
to conceal. In these systems the exhaust pipe ran vertically from the centre of
the floor to the joist space, and then between the floor joists to the wall.
31
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7.1.3. Floor Patching
Only house #4 had a 50 mm layer of clean crushed stone beneath the floor
slab. At the other houses, the thickness ranged from zero, with the slab
poured on top of bedrock at houses #1, #4, to 25 mm of loose bedrock at house
#3. The bedrock surface was exposed in the bottom of each hole cut through
the slab, and was broken up with the jack-hammer to a depth of 100 to 150 mm
to loosen the fill in the area around the pipe, and reduce the air flow resistance
in the area. The gap between the pipe and the concrete was filled with a
commercial prepackaged mi\ with pea gravel as aggregate. This could be brought
to a good finish to match the floor.
To keep the wet concrete out of the fill, a cover is placed over the fill
before the hole was patched. A variety of materials were tried, including foam
board, sheet steel, and an asphalt impregnated roofing felt. The felt was the
most convenient, as it could be cut to shape easily, and sealed to both the floor
edge and the pipe with an asphaltic sealant. This ensured that the opening was
airtight, and the only function of the concrete was to fill the opening.
7.1.4. Fans
Four different fans were used to po\»er the soil ventilation systems. The
first \%as a small 80 mm diameter plastic, and aluminum axial fan that gave
50 L/s flow in free air and 50 Pa suction at zero flow. These fans were used
for wall ventilation a* one house, and were then used in drain tile ventilation
systems. Their corrosion-resistant design made them especially suitable for this,
but the suction was lower than that generated by other fans.
The second was a low speed centrifugal ventilation fan in a weather
protective aluminum housing, which gave 100 L/s free air flow and 110 Pa
suction at ?ero flow. These were immediately available from a local supplier.
Their large flow capacity but relatively low suction made them most suitable for
wall \entilation systems.
This fan was too large to mount unobtrusively, and u higher suction was
felt desirable, so smaller Hgh speed centrifugal fans without a weather
protectee housing also used. These were small enough to fit inside a uindow
veil with a weather shield above them, or to mount directly onto the end of an
exhaust pipe. Two models were investigated. Both used the same fan body, but
one ran at 3500 rpm with a motor outside the bod>, the other ran at 1700 rpm
35
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with the motor placed inside the body within the fan wheel. The latter was
quieter, but did not develop as high a suction or handle as much air.
The higher speed fan gave 50 L/a free air flow and 200 Pa at zero flow,
and was adopted as the standard unit. Several fans were fitted with flanges to
accept flexible wire-reinforced plastic hose, and were mounted in weather
protective wooden boxes with "child-proof" discharge protectors for use as
temporary fans, and were used for all three typeB of system.
All of these fans were used at the start of the project in 1985. In 1986 a
supplier was located for a centrifugal fan in a plastic axial mounting, complete
with an integral conduit connector. The "150 mm" model {inlet and outlet
connectors 150 mm m diameter) of this fan gave 150 L/s free air flow and
450 Pa at zero flow, and was suitable for use on all three mitigation systems. A
metal screen was available to fit the inlet to prevent children from putting
fingers into the rapidly revolving fan wheel. This model was adopted in late
1986 as the standard fan for all systems.
A version of this fan was also available in a half mounting! which could be
screwed to the outside of a wall for use as a pressure fan. The casing wes of
galvanised sheet metal, and there was no conduit connector. This fan was used
only on the wall ventilation systems at houses #1, #2, #9 with an external
weather protection cover.
The capacities listed for these fans ai'e not the manufacturer's
specifications, but the measured performance of these fans as determined from
pressure/flow tests using the actual field mountings.
7,1.5. Problems
Installation of the systems was surprisingly difficult. The floor slabs uere
all a full 90 mm <3.5 inches) thick, and the aggregate used in the concrete was
either a granite or a hard metamorphosed sedimentary rock. This made the
floors very difficult to break, and compressed air equipment had to be used to
complete the job in a reasonable time.
An experiment was carried out in house #4 to confirm that the electric
demolition equipment that a homeowner could hire was not adequate to break the
floors. An electric demolition hammer (Hilti) was used exclusively to drill a 450
mm diameter ring of holes where the concrete was Lo be removed to install a
200 mm diameter exhaust pipe. N'ot onlv was progress very slow, cnch hole
36
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taking five minutes to drill, but the rotating bit frequently jammed on
aggregate, rotating the drill body. When this happened, only a 100 kg (220 lb)
workman was able to control the drill. The chisel bit was unable to break the
aggregate, so it was not possible to break between the holes to remove the
concrete as a disc. The conclusion was that professional air-powered equipment
was definitely required to break the local concrete, and homeowners could not be
expected to do this work.
7.1.6. Evaluation
Short term measurements were carried out during the summer. Tho
performance of the first three systems was disappointing. At house "1 no
reduction at all was produced in the radon concentration. Reductions were
produced in the other two houses (»2, #3), but the resulting radon
concentrations were still to high to be regarded as acceptable.
This generally poor performance, plus the installation difficulties, led to the
early conclusion that sub-slab ventilation was not likely to be a low-cost or
effective mitigation method in this area of the Reading Prong.
In light of this, and the major installation difficulties, it was decided that
only one more house (house #4) would be fitted with a sub-slab system, and
alternate methods v»ould be sought for the other project houses where sub-slab
ventilation had been planned. House #4 was thought to be more suitable than
the other houses to test a sub-slab system for it was on a sloping site with only
two basement walls in contact with the soil, the basement was undecoraled,
there were no internal block walls, and the floor had been poured in two
sections with a large open construction joint. The results from these houses are
summarised below in Table 5.
The performance was better in house #4, with radon concentrations reduced
to near the EPA criterion of 150 Bq/m3, despite the floor slab resting directly
on the bedrock, and flow resistance of the sub-slab fill being so high that, the
exhaust fan ran stalled with almost no airflow. The centrifugal fan surged,
creating more noise than normal, so the installation was not regarded as a
complete success.
37
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TABLE 5 SUMMARY OF PHASE 1 RESULTS WITH SUB-SLAB SUCTION
RADON LEVELS WITH SYSTEM OFF RADON LEVELS WITH SYSTEM ON PERCENT
HOUSE (Bq/ra') (Bq/m3) REDUCTION
-TW
RANGE ARITH.MEAN RANGE ARITH.MEAN
1 4 660- 7 360 5 950 4 000- 6 960 5 000 16
2 3 260-18 610 8 810 1 110- 2 150 1 760 80
3 31 380-54 580 44 590 18 650-21 050 19 460 56
4 * "1 480* 670- 1 0*0 820 "45
* Insufficient data to determine range.
These results are based upon 1 to 2 days of hourly Pylon measurements
both before and after the system was activated.
The only feasible additional mitigation measure foi" these houses was wall
ventilation, which had not been tried previously. Work at the thr-.e houses
(house *1, 42, #4) in which sub-slab ventilation had failed to reduce
concentrations sufficiently was therefore suspended until experience had been
gained with wall ventilation at other sites.
7.1.7. Comments
A properly operating sub-slab system draws air down through every opening
in the floor and thus prevents the entry of radon-laden soil gas. An extensive
check with smoke tubes was made of the floor at houses ff2 and #1. In both
places the air vas found to flow down through each accessible me jor crack or
opening into the sub-slab space, showing that the poor performance wat. not the
result uf poor installation, for the sub-slub system waa depvessurizing the sub-
slab space as intended. This led to the conclusion that there was a major radon
supply route into thebe houses vih the walls that was not being intercepted by
the sub-elab depressurization.
7.2. PH^SE 2 - GENERAL
Short term measurements were carried out during the winter in houses £1,
*4 both of which had their sub-slab s> stems operating without modification since
the summer. Radon concentrations in both housett were comparable to the
summer pre-mitigation measurements, and to those measured in the pre\ iou«
winter bj the l)ER, indicating that the systems were not effectixe dm mg the
-------
heating season. House #2 had the sub-slab system modified, but radon
concentrations there were even higher than those measured previously. This
was taken aa further confirmation of the conclusion reached in the summer,
that sub-slab ventilation was not a viable mitigation method for concrete block
houses in the Reading Prong.
Despite this discouraging experience, it was decided to try sub-slab
ventilation again in a number of Phase 2 houses. Two houses (#24, #25) had
poured concrete basement walls, 60 there could be no question of radon entry
through the walls, and two (#21, #20) had concrete block walls. The owners of
the first three houses (#21, #24, #25) had seen them built, and said that there
was a good layer of crushed stone beneath the basement floor, and a new
installation procedure using a diamond core drill had been developed to avoid
the use of a pneumatic drill and compressor to cut open the floor.
A sub-slab system was installed in house #22, after a small local exhaust
system failed to change the radon concentrations in the house.
7.2.1. New Installation Procea,:~e (Phase 21
The strong concrete floors met with in thifa area required the use of
specialist machinery to cut them open. Once this was accepted, there were a
number of alternatives to the use a jack hammer. The contractor had a
concrete coring drill, which could cut discs of concrete out of wall or floors up
to 200 mm in diameter, and as it was water cooled and non impact, would do it
with much less dust and noise than the jack hammer.
The largest core that could be removed was much smaller than the openings
that were made with the hammer, and so the volume of high permeability
material that could be placed round the end of the pipe was limited. The core
drill technique was best suited to those places where Ine sub-slab permeability
was high.
The drill was able to cut a 200 mm diameter hole in abcut 30 minutes,
depending on setup time., and could work adjacent to walls. This was rapid
enough that it was feasible to consider drilling multiple holes. The original
sub-slab system design used only one or two central exhaust points to reduce the
labour needed for installation, and relied on thw perme<. bilitj of the sub-slab
matt-rial to transmit the suction from those points to the major routes of radon
entry ut the perimeter wall/floor joint. When tho permeabilit> uas lov>, 'he
39
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suction was transmitted poorly. If the suction were applied near the walls
instead, it would be highest in the region of the routes of entry, and even in
areas of low permeability sub-slab fill, would be transmitted along the footing by
the disturbed material in that area. This might also lower the pressure in the
soil beneath and outside the footing, anu reduce the flow of soil gas into
concrete block walls at the footing level.
7.2.2. Piping
The "4 inch" lightweight plastic piping was used for these systems. The
core drill made it easy to set pipes close to the walls, where they were less
obtrusive than in the middle of the floor, 60 there was less need to go to
smaller diameter pipe to aid concealment.
The sub-slab ventilation systems planned for Fhase 2 work were more
elaborate than the Phase 1 systems. In addition, instead of relying completely
on the system to produce sufficient soil depressurization to deal with all floor
openings, all accessible floor openings were closed to ensure that the sub-slab
suction was as high as readily achievable.
7.2.3. Problems
The core drill was water cooled, and used two or three gallons of water
while drilling a hole. This water could be collected by continually running a
wet vacuum cleaner, but it was found easier to build a small dam round the
machine with sand. The water wetted the sand arid fn pooled inside the dam.
When the core was removed, the water ran away down the hole, verifying that
the opening was connected to the sub-slab space. The sand was shovelled up,
and the area was dry in 30 minutes.
The water cooling made this dm1 suitable for use only in uncarpeted
areas. Diamond bits are available for dry drilling, but the large amount of dust
produced requires a higher standard of dust control tnn.. usual in the contracting
world.
7.2.4. Ev aludtion
The results front the Phase 1 houses that had their systems modified and
the new Phase 2 houses are summarised hnlow in Table 6.
40
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""V.- first house where the new procedure was tried waa house #21. This
house had a concrete block basement, and a carpeted floor and finished ceiling
in most of the basement restricted the location of the exhaust pipe to a single
pipe in the utilitj room at one end of the house, which was connected to a
100 L/s exhaust fan. There was at least 50 mm of crushed stone beneath the
floor slab. Openings in the floor slab around the drains were closed with
silicone caulk, and an untrapped floor drain closed with a rubber plug. A major
reductiou in the radon concentration was achieved in the winter, showing that
high radon supplies through the walls were not inevitable if the sub-slab fill had
good permeability.
TABLE 6 SUMMARY OF PHASE 2 RESULTS WITH SUB-SLAB SUCTION
HOUSE
NO.
RADON LEVELS WITH SYSTEM OFF
(Bq/m1)
RADON LEVELS WITH SYSTEM ON
(Bq/m')
RANGE
ARITH.MEAN
RANGE
P®5^TICW
IN MEAN
ARITH.MEAN
Basements with block foundation walls
7B 5 750-23 150 14 890 30- 240
20 5 460-25 750 10 440 740-2 920
20A 5 460-25 750 10 440 140- 770
21 1 410- 7 440 4 100 40- 150
Basements with poured concrete foundation walls
24
25
888- 2 405
444-11 470
1 628
5 476
74-
185-
185
592
120
1 600
4 CO
100
111
333
93
85
95
98
93
94
Basements with poured concrete foundation walls and adjoining slab on grade
22 814- 1 998
23 3 219- 3 811
1 258
3 515
111-
148-
555
444
259
296
11
92
These results are based upon 2 to 4 days of hourly Pylon measurements in
the basement both before and after the system was acti\ated.
The second house where this new procedure was tried wus house #25. This
house had solid poured concrete basement walls, and a floorslab that had shrunk
away frtjm the walls 2 to 3 mm in places. The owner said that injects entered
the basf-ment via this crack, and that there was a layer of crushed stone
beneath the slab. Four holes were cored through the slab close to each exterior
wall, connected to a 50 L/s centrifugal fan. The top of the fouling was exposed
in all the holes, arid was general)} covered with a 1"> or of small stones, 'llie
11
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sub-slab stone exposed in the holes ranged from 30 to 100 mm In depth beneath
the slab. A major reduction in radon concentration was achieved when the fan
was turned on.
The airflows up the exhaust pipes were lowest where the stone layer was
thinnest, and smoke tests found that parts of the wall/floor joint were not
under negative piessure. This indicated that there could be large variations in
the sub-slab permeability, and that more than one exhaust pipe per wall might be
needed to guarantee that almost all of the floor area was under suction. Closing
the open portion of the wall/floor joint with caulking did not improve the
system performance significantly.
A direct comparison of the effect of pipe location was carried out at
house #20. A central two point system was installed connected to a 100 L/s
fan, using the core drill to cut 200 mm diameter holes. Smoke testa showed
that the suction extended to the edge of the floor slab. This system produced
major reduction in radon concentrations, but there was indication of a small
radon supply via the concrete block walla. The central system was then
removed, and a five point system connected to the 100 L/s fan, with two points
on each of the front and rear walls and a single point on the buried end wall.
The other end wall contained a garage door and \»as almost completely out of
the ground. The new arrangement gave a slightly bettei performance, but there
was still a small radon supply from the walla.
The block walls at this house were painted, and the sill plate covered the
blocks tops. To test if the suction in the tooting area would reduce the raJon
supply if the airlightness of the walls was increased, the sill plate was caulked
to the top of the blocks, and open blocks in the pilaster \>ere closed uith
expunging urrthane foam. This made no significant change in the radon
concentrations, and did not change visibly the effects of v.ind on the airflow in
or out of the wall, or the radon concentration in the wall. This indicated that
the although the multipoint sub-slab system could work effectively in concrete
block houses, but if there was still a small rndan supply \ la the walln, just
increasing the uall an tightness uotild not allow the random connections from the
sub-slab space to depressun/o the ^alls. If the radon supplj from the waits was
to be reduced, a separate sjsteni would be required.
Mouse c24 had solid concrete basement walls, but a large concrete block
basement chimnej structure in the wall at one end. The owner intended to
42
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finish the bae.em.ertt, and the choice of location, .or the exhaust pipes was very
limited. The ovner had seen the house built, and said that there wbb a good
layer of stone beneath the basement floor, so the final system only had throe
exhaust points, two at the fireplace end of the basement, and one at the
opposite end. Good performance was achieved here with a 50 L/s fan, with
suction extending beneath all parts of the floor.
House #22 was a split level with solid concrete basement wails, and half
the house was over a grade level concrete slab. Operation of a four point «ub-
slab system with u low suction 50 L/s axial fan reduced radon concentrations to
a loi» le\ el.
7.2.5. Comment
The new installation procedure using a core drill effectively overcame oil
the installation difficulties caused by use of a.i air powered jai-k-hainmer m
occupied houses identified in Phase 1. The good system performance irt these
houses, without excavating the sub-slab fill around the pipe entry, plus
knowledge gained in installing mitigalive systems in other houses, suggested
that the houses selected in Phase ! had features which decreased sun-slab
ventilation performance. It was likely that if they had been fitted ivith multi-
point systems with high &uction fans, good results would have been obtained
there.
7.3. PHASE 3 - GENERAL
The experience in Phase 2 hnnpes with sub-slab \ eritilation, and with wall
ventilation combined wtlli sub-slab ventilation, suggesled Ihat sub-slab ventilation
could be effective in a wide range of housing types. As a result, ull the
Phube 3 houses were to receive sub-slab ventilation as the prunarj mitigation
measure. Sis. af thom (r36, £33, ?-10, #34, #37, $3f>) had solid concrete bnsement
walls so there was no concern for radon entry via the walls, and three (f32,
339, ±31) had concrete block walls.
In addition, as a specific test of the improved design, house =4, where nn
unsuccessful two point sub-slab system had been instnlled, w.»t> to receive- « new
design aii point s} stern. Two Phase i houses (#53, *6) with concrete block
basement walls where other systems had been unsuccessful were to bu nnncrtrd
•13
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to sub-slab ventilation. One Phase 1 house (#38) which had not had any system
installed was to receive a sub-slab system.
Two Phase 2 houses (#22, #23) which had a sub-slab system exhaust system
in the basement section alone, were to have the system extended to the grade
level slab.
7.3.1. Installation Procedure (Phase 3)
The installation procedures were generally the same as used in Phase 2.
The "standard system" had six exhaust points, two on each long wall of the
house, and one on each end wall. If the basement was rectangular, only one
pipe was Used at the centre of each wall. More points uere added in large
houses. All accessible floor openings, such a9 construction joints and openings
beneath well pressure tanks were closed. The 150 L/s fan v. as used in all new
installations.
A four point exhaust system vas installed in house fl3, where weeping
tile exhaust system installed in Phase 1 produced only moderate reductions.
As a test of the ability of the multiple point system to deal with
conditions of poor sub-slab permeability, a six point system was installed at
house £4, where a two point system was ineffective in Phase 1.
House (£38) had concrete block walls and a french dimn. Half of the
basement was finished as a laundry room, bathroom and family room. The
accessible part of the french drain was in the garage, and was closed by
placing -10 to 50 mm of snnd in the bottom of the drain, and then Tilling the
remainder with mortar. If water entered the wall, it \»nuld leak out at the
bottom of the vvall, and diuin to the sub-slab space via the sand. The parts of
the drain that were concealed behind paneling \»crc closed bv injecting
expanding fonm through small holes drilled through at the foot of the wall.
These were concealed by an added basebonrd molding.
The system at house uas converted from a wall plus floor ventilation
s,\ stent by remo\.ing the evhaust pipes and the garage fan from the v.a!ls, and
using the three holes in the floor of the unfinished , art of the basement sa the
o\hin.ist points ;oi' the .,ub-slab svsteni.
House -32 had concrete block v>.»lls, and a large sump pit that contained
the v.ell pump and piessure tanks. This pit was normally ro\eied v»ith .»
pljunod sheet. In addition to installing si\ peripheral sub-slab \ eiitil'ition pipes,
-------
a fitted plywood door was placed over the pit, and it was ventilated with a
separate line.
Houses #36, #22, #23 had half of the house on a grade level slab. A sub-
slab system vas initially installed in the basement alone at #22, and £23, and
then the slab vas treated by placing' an exhaust pipe into the sub-slab fill. Ar
extended system was installed at #36 from the beginning.
House #37 had a family room on a grade level slab. A system was
installed in the casement only.
House ?34 had concrete v«.alls and a french drain. The drain uas filled
with mortar over a layer of sand, and a standard si\ point system installed.
Most of the basement at house #35 was token up with a garage, lea\ ing
only h sniill work room. A four point system was installed 111 this room.
A non-standard s\ slom was installed at house £33, where there vas a dry
sump with no connection to n drainage tile. A cover was placed over the sump
and it was ventilated with a high suction fan.
7.3.2. Fans
A supplier of a series of in-line centrifugal exhaust fans was identified
late in Phase 2. A suitable unit was available with a weather protectee plastic
housing that would give 150 L/s free air flow, and more importantly, pioduce
450 Pa suction at zero flow, and more than 200 Pa suction Ht any flow less than
80 L/s. The inlet and outlet connectors would just fit inside "si.\ inch"
lightweight plastic pipe which v*as convenient for mounting. This fan uas
adopted as the standard unit for new installations, and was letrofitted to most
of the previous ones.
7.3.3. Comment
A test procedure had been developed by another contractor to measure the
airflow resistance of the sub-slab fill, to pro\ idu guidance as to the sixe of
system required. The basic idea was to drill a small hole through tin* stab nt
the proposed silt1 of the exhaust pipe and intervals over the slab, sin k on one
hole with a high suction \ncuum cleaner, and measure the decinasc of pressure
with distance Ti-om the hole. The flow out of the test hole was nlso measured,
so that a fan with sufficient flow capacity could be specified.
45
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A modified version of this procedure was tried at houses #39 and #40. A
professional 1/2 inch rotary/hammer drill was barely adequate to drill through
the floors. It took several minutes to drill through the pieces of hard
aggregate that were encountered in almost every hole. At housp #40 the sub-
slab permeability was so low that there was no measurable pressure difference
(4 Pa), or even airflow down holes only 450 mm from the test hole with 15
000 Pa suction applied. At house ^39, only one pair of holes had a measurable
connection, and a suction of 25 Pa was measured at a distance of 1.3 m frora the
test hole.
This was a valuable test in that it suggested the system flows would be low
enough that one exhaust fan would be sufficient at #40, which was a very large
house. The overall conclusion was that the sub-slab permeability 111 these houses
was too low for the modified test procedure to be very useful as a design guide.
7.3.4. Fvaluat ion
The results from the Phase 1 and Phase 2 houses that had their systems
modified and the new Phase 3 houses are summarised below in Table 7.
As a test of the abihtj of the multiple point system to deal with
conditions of poor sub-slab permeability, a six point system with a high suction
fan was installed at house #4, where a two point system was ineffective in
Ph nse 1. This \%as successful, and gave reassurance that increased and videly
distributed suction could overcome low permeability.
House $7 originally had a wall ventilation system installed in Phase 1, and
considerable effort was spent in Phase 2 to impro\e the performance. The
system converted to a sub-slab sjstem, and good results were obtained. The
sj stems at. houses £6, #38, £39, r31 were also successful, confirming that sub-
slab ventilation alone could reduce the enlrj rate of soil gas and radon, even in
houses with concrete block basement vails.
The sjstem at house =32 reduced the radon concent i ations, but the
premiligation concentrations v«ere low. It vwis subsequently discovered that the
DCIJ alpha-track detector v>hich indicated high long tei in average radon
concentrations was exposed in the sump pit, and did not represent a valid
estimate of the average radon concentration in the basement. The house would
not huv e qualified for the program if a icalistic measurement had been made.
-------
The sump ventilation system at house #33 initially produced only a small
reduction in radon concentration, and the sub-slab suction was limited to the
region round the sump. Holes were drilled in the side of the concrete pipe
sump liner, and in the bottom of the sump. It was found that the pipe was set
in concrete, covered by a layer of stones and dirt, rather than being open to
the sub-slab fill as it appeared. Satisfactory performance was achieved after the
comruunicaUon was improved.
TABLE 7 SUMMARY OF PHASE 3 RESULTS WITH SUB-SLAB SUCTION
RADON! LEVELS WITH SYSTEM OFF RADON LEVEIES WITH SYSTEM ON PERCENT
HOUSE {Bq/m3) (Bq/m') REDUCTION
!\U.
RANGE
ARITH.MEAN
RANGE
ARITH. MEAN
rUiA.\
Basements with block foundation walls
44
550- 900
740
40-
160
100
86
6B
1 300- 3 610
2 210
100-
220
180
92
7D
5 740-23 150
14 890
40-
330
150
99
13A
2 780 4 330
3 500
20-
150
80
98
20C
5 460-25 750
10 440
110-
260
160
98
31
15 510-19 490
17 945
80-
240
130
• 99
32
110- 410
210
20-
100
45
79
39
40- 2 330
890
20-
110
60
93
Basements with poured. <
concrete foundation
walls
33
2 553- 3 589
3 108
111-
259
185
94
31
20 313-29 970
25 752
111-
259
185
99
35
3 219-11 026
6 068
18-
74
37
99
Basements with poured
concrete foundation
walls
and an
adjoining slab
on grade
22A
814- 1 998
1 258
185-
592
333
74
23A
3 200- 6 000
4 700
40-
950
450
90
36
2 442- 6 327
5 254
37-
148
74
99
37
370- 1 221
703
18-
74
37
97
These results are based upon 2 to 1 days of hourly Pj Ion measurements in
the basement before and after the system was activated.
In houses #40, #34, £37, and *35, where the basement \%alls \*i>re all of
solid concrete, the systems were successful and achieved lo\> radon
concentrations. House #37 had a farrul\ room on a slab adjacent to the
basement, but reduction in basement radon concentrations still led to lo\* radon
concentrations upstairs.
17
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At house #13, operation of the sub-slab system at the same time as the
weeping tile system produced low radon concentrations, but the system by itself
was not much more effective than the weeping tile system. An explanation for
this is that the systems produce asymmetrical but different pressure fields. Tins
house is unusual in that the bed of crushed stone beneath the floor slab is much
thicker than normal at the rear of the house, as it was used to level a sloping
excavation. The flows in the sub-slab exhaust pipe from this location were high
and the radon concentrations very low, indicating that this section was drawing
mainly atmospheric air, not soil gas. The weeping tile in this section is nearest
the fan, and has the highest suction.
At house £22, radon concentrations upstairs were higher than m the
basement, so the fill beneath the grade le\ el slab was ventilated with two
exhaust points inserted through the stub wall. This reduced radon
concentrations upstairs to low levels, but basement radon concentrations
remained slightly elevated.
At house »23, with just a sub-slab system in the basement, radon
concentrations upstairs were higher than in the basement. Therefore the fill
beneath the grade level slab uas ventilated with a single exhaust point through
the slab, placed in a closet beneath the stairs. This reduced radon
concentrations to low levels both upstairs and in the basement.
7.4. OVERALL EVALUATION' OF SUB-SLAB VENTILATION
The initial Phase 1 sub-slab installations performed poorly, and led to a
premature dismissal of sub-slab ventilation as an effective mitigation method for
the Reading Prong area. In retrospect, the reasons for the poor perfoi mance
were largely that the design was based on e\perience in areas uhere the sub-
slab permeability was much higher than in this area. When the design uas
modified to compensate for the lower permeability, by use of multiple e\haust
points, closure of all accessible floor openings, and high suction exhaust fans,
then large reductions in radon concentration v%ere obtained. The step of most
value seemed to be use of multiple e\hnust points, for improvements lit system
perfoi mance were minor wht_n higher suction fans were installed.
These steps also reduced the entrj of soil gas thiough concrete blocK
vails. The good performance of the later sub-slab systems suggested that in the
majority of houses the depressu rizat ion v*as not limited onlj to the sub-slab
4S
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region, but extended beneath the footing to the outside of the basement walls.
In these cases there was no need for a separate sjstem to drfpressurize the soil
outside of the walls, or collect the soil gas from inside the walla.
Split level houses? and basement houses with extensions- could be dealt with
successfully by ventilating beneath both floor slabs.
However, desp-te the excellent performance of the modified system in most
houses, there were some places where the performance was poorer. These
include both houses with concrete block walls (where the walls could be an
untreated .source) such as house #13, and #20; but also places with colid walls,
such as house £23 where the reasons for poor perform-nc-ti must be related only
to low and variable sub-slab perTe-ibiltcy. Tests of the effective sub-slab
permeabilitj may cimbie *.:s to identify these places in advance, but it is not
clear how much the tests will assist in designing the systems to overcome this,
other than by pointing out that there is a problem.
10
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SECTK>N 8.
EXPERIENCE WITH PERIMETER DRAIN VENTILATION
8.1. PHASE 1 - GENERAL
In previous projects, active soil ventilation using the perimeter drain tile
(weeping tile) as the soil gas collector had been a generally effective mitigaiive
mensure for concrete block structures. However, only about 30% of houses in
the Boyertown area have perimeter drain tiles. Houses that had them were
commonly built into the side of a hill, and the tile drain was intended to
intercept water moving downhill through the soil after rain and during the
spring melt. These drains are often omitted on the downhill and garage walls
of the basement, so the fraction of houses where there was a complete loop of
tile round the basement was smaller still. The collected water was normally
discharged by gravity down the hill, rather than brought to a sutnp inside the
house.
Some basements without perimeter drainage tiles have a "French Drain".
This is an opening about 50 mm (2 inches) wide between the edge of the floor
slab and the basement veil, exposing the upper surface of the footing and the
sub-slab fill. Water that enters the concrete block wall weeps down the wall
surface, and is collected and drained to the aub-slab fill without flowing onto
the floor surface. These houses present a major challenge, .or not only are
there the usual routes of soil gas entry through the floor and walls, but also a
direct route from the soil via the french drain.
The soil in the area is believed to be free draining, and this is piobablj
the reason why perimeter drain tiles are not installed routinely. However, on top
of the hills the soil is a mixture of rock, clay and sand. Most of the houses
inspected had sow: signs of water entrj through the block walla, so the drainage
capacity is not always good enough to deal with high unter loadings, such as are
found during the spring tha\\.
The drain tile installations tested during this study were of two types.
Where the tiles drained to an nbove-ground discharge, the s>stem resembled
that shown in Figure 2. Where they drained to on internal sump, the system
resembled that shown in Figure 3.
50
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Exhaust (preferably ralosced
above oaves)
Note:
1. Closure of major
•lab opertngs is
important.
Riser connecting
drain tila to fan
Capptd riser to add
water to trap
Discharge
lino
¦//&*>• r\.y
A* »l ^ r'
... i#.
discharge f
' His
[2 v<* ~ :w fr-%. • • • . .
voc-.* .A{ -;•«
Condensate
Wpi
*# *? *
r->.
SuJ 338
Sealant'
* V-V/ ^
'aS» *»*¦"
. V • *
r w.T H --:V® " A v^d'jV^vt-ysioCaGS
Footing-. >• •<~. '•":i-'
Existing drain tile circling the house
-Water trap to prevent air from
being drawn up from discharge
FIGURE 2 TYPICAL DRAIN TILE VENTILATION SYSTEM
{ABOVE-GROUND DISCHARGE)
51
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Exhaust
Outside
fan
(optional)
Slop* horizontal
leg down
toward sump —i
guard
Grass level
Optional
piping x
configuration
Sealant
rVi
To exhaust fan
mounted in attic
or on roof
Note:
1. Closure of major
slab openings Is
important.
- Suction
plpo
-3Ttc!i«t
(option)
Sealant'
Saalant
Water
Aggregate
Existing exterior drain
tile circling the house
-Sealant
Water dischsrge
pipe (to rsmato discharge)
^^Masonry bolts
^V^-Saalant
Sump
Submersible
pump
FIGURE 3 TYPICAL DRAIN TILE VENTILATION SYSTEM
(INTERNAL SUMP DISCHARGE)
52
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8.1.1. Installation Procedure (Phase 1J
The drain line from the perimeter drain tile is open to the air at the
discharge end, so the tile canno1 be used as a soil gas collector until that
opening is closed. Otherwise the fan will just draw air from the atmosphere,
instead of depressurizing the soil around the basement. A pit was dug to the
junction of the perimeter drain tile and the drain line, a water trap placed in
the drain line to close it against the passage of air, and a vertical riser for the
fan attached to the perimeter drain tile.
The "L*" water trap was fabricated from "4 inch" plastic drain pipe elbows.
To prevent the water from freezing during the winter and perhaps 1.locking the
trap during a sudden thaw, each trap was covered with at least 600 mm (2 feet)
of earth. In these initial installations, a vertical riser topped by a cap was
attached to the atmosphere side of the trap so it could be filled with water
after it was buried, and the water level checked from the surface. Although
there was a drought in Pennsylvania, the water levels in the traps did not fall
visibly o\er a month, showing that evaporation should not be a problem.
A perimeter drain tile ventilation system with a sub-slab component was
installed at house #17. This house was unusual for the area in that it had an
internal sump and pump to dispose of the water collected by the peiimeter
drain tile, and there was also :» tile network beneath Lhe basement floor. This
had been installed in a bed of crushed stone over the top of thp original
basement floor, and a ncu flo ^r slab poured over all. The house uas at the
foot of a small hill, and the owners stated that large amounts of uater were
handled by the system when rainfall was normal. Most of the basement was
finished. The sump and pump were concealed in a corner by panelling.
An airtight wooden cover was constructed to fit in the available space,
and a "4 inch" plastic sev%er pipe uns installed behind Lhe panelling to ventilate
the sump. 11 rar through the wall into the garage \»here a free standing fan
v.hs placed, discharging to (he outside. There was a considerable gap \isible
between Hit floor slab and the wall in the sump area. This uus filled uilh
expanding foam to decrease the leakage area into the system. The gap extended
behind the panelling, and no attempt \*as made to remove the paneling to close
the gap for ihat uould not have been lo\* cost.
More details on Lhe installations are given in Appendix C.
5^
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8.1.2. Fans
Two different fan installations were used. At the first three houses #12,
#13, £14) a small axial fan of 50 L/s (100 cfm) capacity and 50 Pa suction at
zero flow was installed on the end of a 900 mm (3 feet) vertical riser. When the
corners of the 130 mm (4.25 inch) metal frame around the fan were cut off, it
fitted inside the large end of a 6x4 plastic drain pipe reducer. The gap between
the edge of the frame was filled with an single component expanding urethane
foam. A protective wire grill was bolted in front of the fan to prex/ent children
putting their fingers into the rapidly revolving plastic fan blades. Two of these
fans had to be replaced, for unreacted foam seeped between the rear of the fan
frame and the adaptor, expanded into the fan blades, and jammed them. The
solution was to use a "reverse mounted" fan with the mounting spider on the
suction side of the fun. This enabled the fan to be screwed down against a soft
rubber gasket without fouling the blades, and all further axial fans used were of
that type.
The 6x4 reducer was attached to the vertical user fioin the perimeter drain
tile water-trap by an inverted "U" made of two elbows, so that the fan
discharged downward, and was protected from thu leather. The riser was able
to support the fan without additional bracing. Although the performance of
these fans was satisfactory, a higher suction v,as felt to be desneable for the
larger houses with higher radon levels.
¦\ different fan and mounting procedure was used for the next three houses
(£10, ?15, #1G). A small centrifugal fan of 50 L/s capacity and 200 Pa suction
at zero flow was mounted m a free standing uooden box, and connected to the
riser with 100 mm diameter wire reinforced plastic hose (dryer hose). The fan
was hung inside the bo\ from its discharge port flange, a plastic toilet flange
was screved to the metal fan bod> as an intake adaptor, arid a 300 mm length of
"4 inch" plastic pipe viith an elbow was placed o\ er the dischatge opening lo
prevent children from putting their fingers into the rapidly resolving metal fan
wheel. This v,as a temporary nn ungement, for the uir leasing the soil is
saturated with \»ater vapour, and in cool leather this will condense in the
discharge; piping, blocking the flexible hose if it has a lov. spot.
51
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8.1.3. Problems
There were no unexpected installation difficulties. The ground was stony,
and so the effort involved in digging to the tile was high. In some areas it was
impossib'e to insert a spade point into the ground, for it would always strike a
small stone. It was necessary to break up the soil with a pickaxe or a crowbar
before it could be moved with a spade. An electric hammer with a chisel blade
was found to be a considerable assistance. We were fortunate in that many of
the homeowners had seen their house built, and were able to tell us where the
tile ran, and where the drain connection was. This greatly reduced the amount
of digging needed to find the junction of the drain line and the tile.
The perimeter drain tile was buried only 300 to 900 mm (I to 3 feet) deep
at the reav of mosi houses on sloping sites. This minimised the labour requned.
At one house (house ?16) there was a full depth basement, and the excavation
was over 2.1 m (7 feet) deep. Tins pit was dug on two days of record breaking
temperatures, and one of the labour crew resigned during the task. When the
fan vds turned on in house #16, the untrapped floor dram was found to be
connected to the perimeter drain tile. A commercial watertrap adaptor to close
this drain is not available, so an expanding rubber plug was placed in the drain.
8.1.4. Evaluation
Short term measurements in the summer ga\ e good results from all these
systems. Soil ventik tion with the perimeter drain tile as the collector seemed to
be an effective ua> to deal with soil gas entry routes. As the greatest suction
is near the footi'i/, the good success of this method, together with the relative
failure of sub-slab collection, indicated that the major enti y route in these
Reading Prong houses uas \ in the \%alls. This in turn suggested that wall
\ entil.it ion might be an effecti\e mitigation strategy for those basements without
perimeter drain tile.
Inspection of the sj stems in the late fall of 1985 found that the- flexible
hose to the freestanding fans \»as filling uith \»ater during the cool nights, and
Blocking the airflov to the fan. To keep the sj stems operating through the
¦uin'ei, the fans were mounted direetly on top of the evhaust riset s. This
inrreused Lhe suction in the systems. The low suction 50 L/s axial fans \>ere
hIso replared \oth direct mounted 50 1/s centrifugal fans i^ith high^i suction.
-------
To direct mount the centrifugal fans, they were removed from the boxes,
and were placed directly on top of the exhaust riser pipes with a 4\3 reducer
attached to a plastic flange screwed to the metal fan body. These fann were
not weather protected, so a length of flexible plastic hoso was slipped over the
top of the fan to keep the motor and terminals dry.
Short term measurements after fan remounting found the system was
effective at houses #12, #10, #15, where the perimetei* drain tile comiiletelj'
surrounded the basement, but was ineffective at house £16, where the tile ran
only partly round the basement. Af house £13, where the tile ran only part
way round the basement the low suction axial fan was replaced with a 50 L/s
centrifugal before any measurements were made, but measurements showed that
even with the higher suction fan the system was not very effective. The
system nt house #17 was found to be ineffective even with the fan opeiatmg
properly, and wus removed.
The system was effective nt house 312, ovcept when the internal pressure
was lowered by running an open fire. Replacement of the axial fan by a
directly mounted 50 L/s centrifugal fan increased system suction from 50 to
100 Pa, and improved the performance.
The system was ineffective at house £14, where the tile ran onlj along
thi ee sides of the basement, and there was a low suction a\ial fan. The system
was removed from this hou&e, as the poor performance of sj steins at houses
where the perimeter drain tile did not make n complete loop suggested that
other mitigation methods l.ere needed.
8.2. THASE 2 - CENTRAL
I'Oiir new Phase 2 houses had block basement walls, and were said by the
owners to have perimeter drain tiles which ran completely round the basement,
and uer" therefoie selected for perimeter drain tile ventilation. Two houses
were selected to test the effect of internal openings on s\ stem perfoi manco.
House #2F. had a g.irago m the basement, and tile was adjacent to I he ,'t
buried walls. Tliei e was a cold room with a soil floor underneath the Tinnt
poich, with a door into the basement, and the floor was poured in several
sections. Mouse £27 had i large conciete block sti m tuie in the centre of ihi;
basement that supported a upstuns fireplace and flue.
.">6
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The 50 L/s axial fans were used at each of these houses, with good
results. A concrete slnb was poured over the exposed soil of the cold room
floor at house #26, with only a .small reduction in radon concentration. This,
and the generally good performance in both houses indicated that the perimeter
drain tile system was able to divert soil gas awaj from the floor openings as
well as from the walls.
Detailed inspection of the site at house $28 led to the conclusion that the
owner might have been mistaken about the presence of a perimetsr drain tile
drain. There was not enough slope on the site for an external discharge front
the tile, and although theie was an internal sump with a sump pump, only one
small diameter pipe led info it. The main use of the sump was as a discharge
point for the; basement washing machine. The basement walls in the sump area
were hea\ ilj water stained, and the owner complained of surface walei entering
the basement despite regrading the site. Taking all these things into
consideration, it was felt that it would be undesirable to do any extei na!
excavation on this site. The sump uould be ventilated, and if that was
unsuccessful, a HRV would be installed.
A fifth Phase 2 house, =21, had been considered for drain tile ventilation.
Howe\ei, detailed inspection of the site, and discussions with the owner found
that the attached garage had been added to the house a few jeai s after it wa';.
built, and the perimeter drain tile along the garage wall might have been
rerouted or damaged during the addition. The original perimeter dram tile
drainage discha-ge pipe was probably underneath the garage floor slab, and no
other discharge pipe could be found. Rather than undertake the extensive
excavation that would be needed to expose the tile, it. was decided to install
sub-slab vertiLation in this house, as discussed in Section 7.
A supplier of lai ge plastic body m-linr 150 l./s centrifugal exhaust fans
was located at the stai t of Phase 2. These fans weie weather protected, had
built-in conduit boxes, and ivci f suitable fur a permanent electrical connection.
These fans would develop loO Pa suction at zero flow. All the pellmeter dram
tile exhaust fans were replaced with these fans dm mg I'hase 2, except for
houses -Ifi, =17, which had been converted to othei mitigation svsteins. \\>ne >>f
the new houses selected for l'huso 3 had perimeter drain tile.
/
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8.2.1. New Fan Installation Procedure (Phase 2)
The inlet and outlet connectors of the new fan would just fit inside a
"6 inch" light weight plastic drain pipe. The fan was secured to the pipe with
three sheet metal screws, and Lhe pipe attached to the "4 inch" vertical riser hv
n 4x6 coupling.
8.2.2. Evaluation
Results from both the Phase 1 and Phase 2 installations (except for houses
£15 and #17 vherc the systems were replaced) with th** new high suction fans
in operation nre shown below in Table 8.
TABLE 8 SUMMARY OF PHASE 1 AND 2 RESULTS WITH DRAIN' TILE SUCTION
RADON' >.EVELS Km) SYSTEM OFF RADON LEVELS WITO SYSTEM ON' PERCENT
HOUSE (Bq/mM IBq/m*) REDUCTION
\0 j\i MPfVV
RANGE ARITH.MEAN RANGE ARTTH.MEAN
Ti 1 es drain to low point on site
10
3 400-11 400
7 400
70-
550
250
97
12
220- 740*
440*
70-
130
100
77
13
2 220- 3 260*
2 660*
150-
630
120
81
1 t
1 960- 2 480*
2 220*
300-
850
580
74
15
ISO- I 810*
670*
15-
no
40
94
ir,
5 030-12 lOOt
8 880*
3 030-8
140
5 580
37
26
1 ISO- 7 070
3 310
15-
70
10
99
27
670- 2 370
1 550
10-
330
110
93
Lies
dram to interior
sump
17
920- 1 630*
! 180*
480-
850
670
43
28
u
-soo
380-2
500
800
"0
29
150- 3 330
1 710
40-
130
70
96
* All measui-umvi.ls iwirkcd v.Uh an asterisk vt»rc made in warm weather-
July to August. Nadon levels nrr- expected to be highest during cold weather
duo lo increased thermal stack effee', and to the house window*, being closed.
** Insufficient data In determine range.
These results .lie bafod upon 2 to -1 days of hourly P.\ len mnasti foments ni
lhe basemen! befote and after i he system was activated.
Installation of the tin> funs increased system suction to mound 200 I'a,
generally with ruilv a slight improvement in performance. results were
58
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obtained at all the houses, with the exception of house #13, \\hich was the only
one where the tile did not completely surround the basement. Concentrations
remained high despite the increase in suction, indicating that the distribution of
suction in the soil around the basement was as important as the size of the
suction developed in the system.
8.3. OVERALL EVALUATION OF PERIMETER DRAIN TILE VENTILATION
The performance of perimeter drain tile ventilation in those houses w'lere
the tile formed a complete loop around the basement was uniformly good. The
affect was not confined just to houses vith entry routes in the walls, for good
reductions were obtained in houses v. here there were internal block vails md
other openings in the floor slab. On the sloping sites common in this ;irea, the
work required to install the sj stems was minor, for the dram tile \%as often only
500 to 800 mm below the surface on the down slope side of the house.
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SECTION 9.
EXPERIENCE WITH WALL VENTILATION
9.1. PHASE 1 - GENERAL
There ai? many small openings on the outei face of concrete block
basement vails in the footing area where soil gns can enter. If sab-slab suction
docs not reduce the soil pressure in this area, and there is r.o keeping tile,
there is no simple way to lower the pressure in the soil in the footing area.
Ventilation of the block cavities to mtei cept the soil gas and radon that leaked
into the vail before it entered the house had been suggested as a possible
mitigati\e measure, but had not been tried previously.
In all but one of the Phase 1 houses, the voids in the top course of
blocks v,ei e open to the house atmosphere, or ut best, closed only by the
sillplate on which the floor joists rusted. There vus a course of solid cap-
blocks on top of the wall in onl\ one house. V\"all ventilation could only be
expected to be a practical mitigation measure these voids could be closed veil
enough that a small fan vould be able to piodure a pressure drop large enough
to ensiue that air flowed f i om house to wall, on en when the exterior pressure
vas i aised b"> vmd bloving against the wnll. The pt>rtei\ed nvajoi problem vas
that of closing the top block \oids. 1 nstallntion of the fans \»as anticipated to
be a minor problem in comparison.
\ topical wall ventilation s> stem is shovn in Figure 1.
Vali ventilation vas tested iri four house during Phase I. The first house
selected for a vail ventilation installation vas ?lf>, for this vas the one «»ilh
solid cap blocks at the top of the vail. Discussions vith the ovner re\e3S capped at the top, but vere internally reinforced
by filling a vertical set of block \ouls at each coiner and at 2.1 m (8 feet)
iriteitals along each vail uiih concrete. As this i.ut each \>all up into several
an tight i.ompartments, a multiple point < olleclion nctvork vould be needed to
drav an fioni everj v.al! coin pa i tmcnt.
CO
-------
Protective
grille
Outdoor
6 In. dla.
collection pipe.
To connections
Into other walls
Notes:
1. Closing the veneer gap may
be Important in some cases.
2. Top voids must be closed as
effectively ma possible to
avoid excessive leakage of
outdoor air out of the void
network.
3. Closing cnejor slob openings
is fmpoitant.
Sealant
Fan
Venear B*P
Close top voids'
Top void
Bnck veneer
Outdoor elr—^-
pressurizing -V-;
void network
Outdoor air through btsrk pcres.
unclosed cracks, ond holes
I .
Concrete block
* Ventilation
point
Utility pipe
Soil gas
A.-
-------
As the house also had weeping tile, it was decided to see what effect weeping
tile ventilation had on radon concentrations, before proceeding with such a large
piece of work. In any case, although success at this site would have been proof
of principle, it would still have left unanswered the question as to how well the
system would work when the wall top had to be closed as part of the work.
9.1.1. Installation Procedure (Phase 1)
Wall ventilation was first tried at house #5. This house was unusual in
that the floor jcists rested directly on top of the basement walls, without a
sillplate beneath them. The block voids here completely open, but were only
accessible in 35 cm (14 inch) segments between the joists. This was also the
only house where more than the top block course of the basement wall was
exposed above grade level.
The tops of the walls were closed with sheets of roofing felt cut to fit
between the irregularly spaced joists, and were stapled to the joist and header,
while the junction between the felt and the top of the block was closed with an
asphaltic sealant. The area around the electrical panel where the wires
prevented placement of a strip of felt was closed by injecting a single
component urethane foam. A small 50 I./s axial exhaust fan was installed m
each wall.
At the other houses there was insufficient clearance to grade to install a
fan in each wall. At those houses, a collection system of "4 inch" lightweight
drain pipe with an entry point into the top course of each basement wall was
used, connected to either a 50 L/s or 100 L/s centrifugal fan outside the house.
The larger fan uas used in the larger houses.
At house e6, half the basement was finished, and only three walls were
easil\ accessible. The sill-plnte closed the block voids along the front and hack
basement walls, and partially closed the top of the garage-end wall, which was
finished, and \ irtually inaccessible. The voids m the top of the other end will
were closed with a strip of roofing felt stapled and caulked to the liL'ider bo'ird
in the same manner ns at house 45. \ pi network was mstnlled to ventilate
the thiee accessible walls with a single pipe into the centre of each wall wiih a
100 L/s centrifugal fon installed outside. A separate 50 L/s .i\ial fan was
installed in the gcirnge to ventilate the fourth (finished) basement wall.
-------
Visual inspection and smoke flow t^sts at #5 and #6 found that the felt
did not close the openings as effectively as hoped. Although it was
impregnated with asphalt, it still took up moisture from the humid air in the
wall cavities, and warped and pulled away from the wood. Alternatives to the
use of felt were considered, and the most practical included the use of a
wooden strip ("2x4") coated with asphaltic sealant to close the gap between the
sillplate and block edge (this was dubbed the "sticky strip" by the labour crew),
or filling the top block cavities directlj, either with cement or an expanding
foan-.. Both these methods were tried in the ne\t two houses (house 57, -8).
The wall tops at house £8 were closed \> ith asphalt coated wood strips,
with mortar used on the side vvalls, and foam used to fill a few inaccessible
areas. To ensure that radon gas did not leak out of the wall into the house,
the fans were set to blow into the wall. As the air flow would be from wall to
soil, the radon concentration in the wall would be very low. Two 50 L/s
centrifugal fans in parallel were used, to ensure sufficient airflow capacity even
if there were large unclosed areas.
The last installation was made at house kl, which was about three times
the size of house #8. End walls were closed with mortar and expanding foam in
inaccessible places, and the sill plate was caulked to the top of the block wall
along the front and rear walls. Two 50 L/s centrifugal fans were used to
compensate for the larger wall areas, and good results were also achieved here.
9.1.2. Fans (Phase 1)
Three different fan installations were used. At the first house (£5)
small axial fans of 50 l./s (100 cfm) capacity and 50 Pa suction at zero flow
ware installed. A protective wire grill was bolted in front of the fori to
prevent children putting their fingers into the rapidlj revolving plastic fdn
blades.
Two other fans ken: used at the other houses. The first was a small
centrifugal fan of 50 L/s capacity and 200 fa suction at zero flow mounted in a
free standing wooden ho\, and conniTtod to the central collection duct with 100
mm cli.imcter wuc remfoicerl plastic hose
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pipe with an elbow was placed over the discharge opening to prevent children
from putting their fingers into the rapidly revolving metal fan wheel. The
second was a larger centrifugal fan with a weather-protective aluminum housing,
mounted on a wooden sU»:. *, and connected to the system by 100 mm diameter
plastic hose.
9.1.3. Problems
Closing the blocks with mortar was slow, and physically demanding.
Stuffing the blocks with paper took a long time. A 22 kg bag of cement will
only fill the tops of eight blocks, so considerable time and effort was spent in
just mixing mortar. The mortar was heavy to handle. The task was judged
only just within the capability of the average homeowner.
The use of an expanding foam was investigated as an easier and more rapid
way to fill the Meek voids. Two kinds of single component foam and a two
component foam, available from local stores, were tried as block fillers. The
major use foreseen for foam was in areas of limited access, particularly where
it was not even possible to reach into the cavity to insert paper. None of
these foams uas entirely satisfactory, and a more systematic search arid test
program was carried out in the fall.
9.1.1. Evaluation
The results from the Phase 1 installations are shown i'» Table 9 below.
Both wall closure methods were effective in areas where there was good access
to the top of the block walls. Each method had its own advantages. Th-»
"sticky strip" was quick to apply on unobstructed lengths of wall, where long
lengths could be used. On the walls at right angles to the floor joists, wedges
could be inserted between the strip and the joists to hold the strip in place. On
the walls parallel to the joists this could not be done, and the strips had to be
nailed into position. This did not locate them as well as wedges, and was
slower, but the closure was still effective.
K'nere the block ea\ities ucre readily accessible, the> were filled with
mortar by first stuffing newspaper into the cavity to provide a support lav er
about 5 cm (2 inches) below tne top of the block, and then placing a moist
mortar on top of the paper. The mortar had to he vibrated slightly to fill to
the edges of the cavity. 'lh
-------
shape, and it was hard to fill them with mortar even with vibration. In
general, if there was enough space to insert the paper, the cavities could be
filled readily.
TABLE 9 SUMMARY OF PHASE 1 RESULTS WITH BLOCK WALL SUCTION'
RADON LEVELS WITH SYSTEM OFF RADON l£VELS WITH SYSTEM ON
HOUSE (Bq/ins) (Bq/m^)
NO.
RANGE
ARITH.MEAN
RANGE
ARITH.MEAN
PERCENT
REDUCTION1
IN MEAN
o
6
7
8
0- 74*
1 221-2 516*
3 115-5 180*
1 961-5 880*
40*
1 850*
4 141*
3 700*
999-1 850
777-1 221*
111- 444*
74- 148
1 580
999*
259*
111
46
93
97
< All measurements marked with an asterisk were obtained in warm
weather - June to August.
Levels in House 7 rose to 4 033 Bq/m3 - 18 537 Bq/m3 during cold weather.
These results are based upon 1 to 2 days of hourly Pylon measurements in
the basement before and after the system was activated.
In less accessible areas, the cavities were stuffed with paper arid an
expanding foain was injected over the top. This worked well, and the small
cavities between the blocks could be closed either by injecting foam directly into
them, or by placing a bead of foam on top.
The perforraancp in the first house (£5) was disappointing, for the radon
concentrations in the house rose when the fans were turned on. This was
attributed at the time to the fans drawing rador.-laden soil gas into the wall,
which then leaked into the house through the many openings at the top of the
house walls. (Later v»ork found that sufficient uir v»as dra\\n into the walls by
the fans to depressurize the basement sufficiently thai airflow was leversed in
an untrapped floor drain, which brought in radon and soil gas). Work w.is
suspended at this house while better methods of wall closure wore tested.
The results at hou-se #8 vcre \ erj satisfactory. When the fans were
turned on the radon concentration fe'l almost to background. A smoke tube
survey of the basement walls showed that the u.iclosed areas uere quite small.
The remaining openings were closed by caulking, and the fans reversed to suek
on the walls. The pel formance remained good, and did not detei lorate *%hon
65
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only one fan \»aa used. This confirmed that a satisfactory level of wall closure
could be obtained by the methods available. The success at this house gave
confidence that wall ventilation sj stems cold be an effective mitigative measure.
The initial summertime success of three of these installations was
encouraging, suggesting that wall ventilation might have vide applicability in
the area. However, when short-term measurements were made in cold weather,
only houso #8 continued to show low radon concentrations.
9.1.5. Comment
The reason for running the fans to tuck on the wall is one of
convenience. If the fans blow into the vail, in cold weather the cold air ill
blow onto the inner leaf of the block wall and ma> cause condensation there of
the warmer house air. If the fans suck, warm house air will be drawn into the
wall, but condensation will take place on the cold outer leaf of the wall. This
will not be noticed, and is therefore preferred. For similar fans, the an
leakages in or out of the wall will be similar, so there is no difference in the
impact of the systems on ventilation rate or energy consumption.
9.1.6. Expanding Foams Tested
The first expanding foam tried uns sold in an 150 g {1 lb) household
aerosol can. It had a moderate expansion on leaving the nozzle, and a small
expansion o\ er the next hour. Unfortunately, the foam had to be dispensed
with the can upside down (nozzle at bottom), and there was rarely enough space
between the top of thr» wall and the underside of the floor above to do this.
The foam was effective for caulking joints and openings in vertical wall
surfaces and floors but could not be used for the purpose required.
The second single component foam came in a 4.5 kg (10 lb) commercial
pack, together with a dispensing hose and an on/off control nozzle. The foam
was intended for caulking, and was deliveied from the nozzle m a stick.v bead.
The initial expansion was small, but the foam continued to expand to more than
double its initial \olume over the next few hours. If this foam was dispensed
into a cavity that had been stuffed with paper to provide a support, the
individual foam bends joined lo form a solid mass as the> expanded. This mass
continued to expand and effectively filled the block void. It could be used as a
f>G
-------
caulk in all places where the bead was supported, but could not be used to form
a layer over a large opening like the two other foams. None of the foams used
were fully satisfactory for block filling, but this foam was found useful in
several houses.
The two component foam came in two small aerosol cans, with a dispensing
hose and mixing nozzle assembly. The foem expanded moderately on leaving the
nozzle, with a small expansion over the next hour or so. The hose allowed
access to all places that could be reached by hand, but the nozzle allowed only
on/off control. If the flow was off for more than 20 seconds, the reaction
chamber in the nozzle clogged, and had to be replaced before the unit could be
used again. This was very inconvenient and time consuming, and made the use
of this foam impractical in this work.
The variety of foam properties and packages met with in local stores was
large enough to hope that a systematic search might find a fully suitable foam.
This was carried out in the fall, and a single component urethane foam in a
large commercial package was identified as the most satisfactory to use for
closing openings and voids m concrete block walls.
9.2. PHASE 2 - GENERAL
The systems were modified at houses *5, £6, where the systems were
ineffective in cold weather. Two houses (£14, #16) in which weeping tile
ventilation had been unsuccessful, and one new Phase 2 house (#19) in the same
area and of similar design to house #1-1, had new wall ventilation systems
installed. The voids at the top of the block basement walls of these two
houses were readily accessible, and they seemed to be "textbook" cases for wall
ventilation systems.
9.2.1. Addltional Work On Phase I Houses During Phase 2
Extensive work was cari led out at the houses where the Phase 1 wall
ventilation s> stems were no longer effective, to ensure that leakage from the
walls was not the reason for the failuie.
At house =C>i where the tops of the walls had been closed with felt sheets,
the felt was remoxed and the tup \ouis of the wall weie filled with moilar or
expanding foam. The five n\inl fans were removed, the openings closed, mid a
si\ point wall exli.iust system installed. This had two exhaust points in eich
G7
-------
long vail and one exhaust point in each short wall, connected to a single
100 L/s exhaust fan.
At house sG the felt sheets closing the end wall were removed and the
block voids were filled with mortar. The 100 L/s centrifugal exhaust fan on the
pipe network was removed and replaced by a 50 L/s centrifugal blowing into the
walls, arid the 50 L/s axial in the garage was reversed to blow into that
basement wall.
At house -7, the walls were put under pressuie by reversing the 50 L/s
centrifugal fans, and a smoke stick survey carried out to check the caulking.
Any openings detected were caulked. System peiformar.ee was tested with the
fans both in suction und in pressure.
The wall exhaust pipes at house f7 t>nd ?C entered the walls near the top,
so soil gas would be drawn up the entire inner surface of the wall on its waj to
the pipes. The exhaust points, at these houses were moved to the bottom course
of the walls to improve the wall ventilation efficiency. No imptoveinent in
performance was noted.
9.2.2. Installation Procedure on Additional Phase 2 Houses
A six-point wall ve','nation s> stem was installed at house *14, with one
exhaust point in each end wall and two points in the front and reai walls. Each
pipe dealt with a similar w all area, and uas connected to a cential collection
duct. At house i!6 a four point system was installed m the basement, connected
to a three point system in the crawl space walls. This was later enlarged to a
si\ point sjstem in the basement, with a larger central collection duct to
increase air flow from the rrawlspace walls. Both these systems had 100 L/s
centrifugal exhaust fans mounted on the oxter lor basement wall, and the wall
evhaucl points placed near the floor for better \entilation efficiency. A foui
point system with the e\haust points m the top of the wall was installed at
house *19. The sj stein was u duplicate of that installed at house =8, which was
a house of identical basement demgn. The tops of all wal's were closed with
mortar where access permitted, or else b\ caulking the sill plate to the top of
the wall.
68
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9.2.3. Problems
Several of these houses had brick veneer walls. In this case the basement
wall is of 300 mm (12 inch) block, and the brick rests on the outer 75 mm (3")
of the wall. The wooden interior framing stands on the sole plate which covers
the inner 200 mm (8") of the wall, with a nominal 25 mm (1") gap between the
sheathing and the brick. If this gap were unobstructed, this would be o very
large unclosed opening into the wall. At house #6, the gap was even larger, for
the frame walls stood on top of a course ot 300 mm (8 inch) blocks, which ran
inside the brjck \ pneer to increase the basement headroom. In practice the gap
is partially filled with mortar droppings, but three methods were examined to
close this gap with expanding foam.
The first method uas onlj applicable in those houses where the sillplate
did not cover the block voids completely. Fiberglass batting was stuffed into
the block voids to act as a temporary support, and then expanding foam was
injected into the void with a long nozzle so that the void would be filled even
at the hack. The foam filled the entire block cavity as it expanded, and so
closed both the brick/sheathing gap, and the gap between the block and the
sole plate. This method was used at house #5, where the absence of a sole piole
made it the method of choice.
The second was to drill 6 min holts in the header board at 150 mm
intervals, ami inject foam until it appeared at the adjacent hole. The third was
1o use a hole saw to remove a 100 mm diameter plug from the header boaid,
insert a fle\ible tube through the hole up to 400 mm between the back of the
biirk wall and the sheathing, and then slowly withdiaw the tube while injecting
foam into the space. These methods were tested, and the large hole method
found to be the most convenient. These methods were not used in these
houses.
9.2.1. Evaluation
The lesults from the Phase 2 installations in the houses are summarised 111
Tahlt_* 10 below.
Vvnll \ until: t ion sj stems wr-*re expected to be an effective and complete
mitigation measure because the suction .ri the walls would not onlj p'-event soil
gas from entei irig the house directlv fiom tKj walls, but also becuise the
rmmeious small openings in the wall at the footing would allow the wall suction
60
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to aepressurize the both the wall/floor joint area, and the sub-slab fill as well.
The systems would therefore act as combined sub-slab and wall ventilation
systems, provided that the walls could be closed well enough for a small fan to
produce suctions ar.d pirflows significantly larger than those that would be
induced by wind and teni^ :rature forces.
The generally low sub-slab permeability found in the region prevented the
walls from depressurizing the sub-slab space in most of the houses. Only at
house #14 was there direct evidence from smoke tests of the wall suction
extending into the sub-slab space, and the system performance was good there.
At house #16, a flow of soil gas was measured out of the sub-slab space in the
cra\>l space despite the walls being under suction at the tinie, and good
performance was not achieved until that opening was closed.
The open block voids at the top of the wal. i could be closed at reasonable
expense if the sill plate covered the top of the wall so that the gap between the
wood and the block was small and could be closed b> caulking, ~r by a caulked
wood strip. The gap at the outer edge of the sole plate was inaccessible, and so
this closure was not as airtight as filling the top block voids. The labour
involved in mixing and placement made mortar filling expensive. Expanding foam
was also effective and requited less labour, but the high material cost made it
more costl} than mortar.
The methods used to close the tops of the walls greatly reduced the (.'pen
area. However, inaccessible joints In the sill plate and header board, and the
multiple joints and pores in the concrete blocks themselves prov ided lelativelv
large leakage areas into the walls. As a result, it was difficult to depressurize
the walls without Jiawing a significant amount of air from the basement. 'I his
severely limited the pressure drop that could be produced in the walls, and so
the sub-slab suction produced b> this method was low. In addition to increased
heating or cooling costs caused by this increase 111 ventilation i ate,
depi essurization produced b> operating the fans in exhaust could hack draft
combustion appliances, arid diaw combustion pioducts into the house.
>\l house -11, while the walls were completely under negative piessuie, an
airflow was detected nut of n large floor cnck into the house. At house 47 the
fans wcr<' reversed to fill the walls with fresh air, which nmdc rio diffeien
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the floor were closed, and r&don concenti atiorss in the house vvfre reduced. This
indicated conclusively that the walls were not the only radon source for these
houses, and that 11 le floors would have to he treated as well if radon
concenti ations were to be reduced.
Houses 47 and $6 were converted to wall plus floor ventilation so stems
with a major reduction in radon concentrations. A conversion of house f19 to
wall plus floor was proposed, but refused by the owners who \%eie concerned
that openings in the basement floor might let 111 viator.
TABLE 10 SU'MM \RY OF PHASE 2 RESULTS WITH Bl OCK W\LL VENTILATION"
RADON LEVE1S WITH SYSTl-M OIT RADON lXVEIJS WITH SYSTEM 0\ PERCENT
HOLiSE {i"Sci/in») (13q/'n3) REDUCTION
K°" RANGE AR mi. MEAN RANGE AM Tit. MI 1N %]k^N
Individual suction points in walls
5A 2 479- 7 100
7A 5 772-23 162
14A 1 961- 2 479*
16A 5 032-12 09S
19 777- 1 387#
*
u eather - Juli to August.
-J 2f>5 111- 296
14 87-1 518-2 479
2 257* 18.5- 71
8 880* 74- 259
1 295* 111- 710
185 96
1 181 92
37 98
148 93
107 68
sere obtained in viaim
All measurements marked uith an asterisk
These tesitlls are based upon 2 to 4 da} s of hourly Pj lou measurements in
the basement before and after the s> stem utts activated.
The untrapped floor drain at house =5 *>as found to be o major rudon entrj
loute, despite dtschai ging to daylight in front of the house. tshen the soil
temperature u 'is higher than the air temperature, there v.as a i>tead\
cmsvcrtiorial flou of an up the drain linn into the house, pir.king u[» indoi. oil
the \»aj. In the summer, v«!ieri the soil v>ns coolei than the air, the drain v.,is
not a iiadon entry r ml", for the airflow i.as out of the liou^r; into tlii; diain.
The small dn\u>g foL <:e c.ould he overcome if the basement (>iib de pressu i i^erl b,s
evhmiBt fans, as> ooi u1 red .n l'hase 1. Closing this entt v i.i.ito, full\ closing
the ope-i Mo< ks at the top of the unlls, tind installing a ii* point e\h;mst
s-.sltm pioduc«d si m.ijfn re,J nt: t iuii m radon concenti at ion:.. lie- system ii i»
final!; opni .Her! v.t'li the fan bloumg air into the unlls, l<> .i\ jid dcpiosi.uMj.ing
the basement ;ind hackd i .if ti ng a c.oal stow..
71
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9.3. PHASE 3 - GENERAL.
No houses v.ere selected for wall ventilation in Phase 3.
9.1. OVERALL EVALUATION OF V.ALL VENTILATION
Despite initially encouraging results, wall ventilation was nut as complete a
mitigative method as had been hoped. The generally low sub-slab permeability
prevented the lowered pressure m the walls f om effectively ventilating the
sub-slab space, and the telati\elv large residual leakage areas left in the vails
after closure limited the wall suction to a few Pascal even with large te'is. This
was sufficient to ensure that the airflow whs frnm house into the wall under
nu>st upHthci' conditions, eliminating the uatls as a route of tadoii onlrv, but not
enough lo consistently ivversc the flou s thrcugh floor openings. Experience
\>ith sub-slab ventilation suggests that much higher suction in the sub-slab fill
wns needed for satisfactory performance.
Some houses ^ere operated \oth the iiulls pressurised, which effectively
prevented i adon from entering the v.alls, but also ercouraged soil gas to enter
the house through openings in the floor. In general, slightly lov.er radon
concentrations vere obtained v. ith pr^ssu rization, but concentrations could
ini'D'uso for h few days after turning the system on until the airflous from the
uulls ii.to the sell diluted and displaced the » adon-rich soil gas adjacent to the
basement floor.
Although wall ventilation muld be an effective tieatment, as shown by the
results in linusos -f>, #8, si 4, and *16, it Hid not seem to be a good initial
mitigation straleijv to pursue There uhs a real possibility that e\en after
installing a vj siteip that was mote expensive than a sub-slab ventilation sj stem,
cirn more inn-.ej mimM he leqa'red to install a sub-slab sj stem to tro.it the
licor. Tins ii» illustrated p.irlicu iarly bj house -1 f>t uhore the walls vere
effeili.i-ly < jused and \ eritilated, but radon entry thiough openings m th-*
b is-'iii. nl flooj->} ib Itept ladon concentrations elevated. Bj Uie end of the
pi ojei l> leiice uith stib-sl.ib ventilation systems \*as that a bi'tter order of
cuts uisild be to treat the floor first, i%hirh would general!; be effective m
n h /usi and orlv if that filled, to pi oreod to \>aH ventilation.
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SECTION 10.
EXPERIENCE WITH WALL PLUS SUB-SLAB VENTILATION
10.1. introduction;
Two methods of combined wall plus sub-slab ventilation were tested in this
project. The first involved drilling holes into the lowest course of the block
vail, and placement of a "baseboard duct" to cover the holes and the wall/floor
junction. This duct then ventilated both the wall and the sub/slab space. A
tjpical baseboard duct installation is shown m Figure 5. The second method
involved placement of individual suction pipes into both the wall and the sub-
slab space - a simple combination of the wall and sub-slab \ eutilnlion methods
described in Sections 7 r»nri
10.2, PHASE 1 - GENERAL
Some houses without weeping tiles. ha\ e a french cuain' to deal with
water entry. This is mi opening about 50 mm (2 inches) wide between the edge
of the floor slab a/id the basemen' wall, exposing the upper surfm n nf r!ii>
footing and the sub-slab fill. Vater that enters the concrete block wall weeps
duvn tho wall suifaco, and js eolli-rted and drained to the sub-blab fill without
flowing onto the floor surface. These houses present a major challenge, for not
unl> Hie theft the usual routes of soil gas entrj thiougb the floor mid wulls, but
also u direct route from the soil \ la the french dtani.
A suggested mitigation method for houses which had french dimn^ (
cuici etc block walls was to place an airtight eo\ei o\oi the diain, and di ill
holes thi ough the lowest blocks at intervals, so thai suction on the co\ ei would
also \entilate the wall \. i.i I he holes. Radon laden soil gas would be collect- 1
fiom the wall, and from the soli connections to the fieni.li di nin. The function
c»r the diain would iiwl be l ni p< t n ed, for wntei that entei ed I lie wall would slill
be able to flow out to the diain thiough the holi s.
The irajoi probl.-ifin with ttns roni opt weie w hul wnt the- best wa.\ to pl.ice
a ctnec o\ei the fiench diain, and how to pchieNe small •¦nuiigh open wi eas in
the wall and the cover loi it In be a practical solution.
73
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Protective
grille
¦ Veneer gap1
Outdoor
air
Notes
1. Closing tha veneer gap may
be important In some cases
2. Top voids must be closed as
effectively as possible to
avoid excessive leakage of
outdoor air out ot the void
network.
3. Closing major slab openings
is Important.
Close major mortar cracks
and holes in wall
Outdoor air through block pores,
"^unclosed cracks, and holes
Sealant
Brick veneer
Close top votds1
Top void
' ;-v Concrete block
Opening »n pipe
Sealant around entire tesm
where pipe penetrates duct
Masonry ecrew
Sealant
Drilled hole
Outdoor
air
. C^'.T V b
Aggregate
P iFooling
Ventilation pipe tightly
caaled into baseboard duct
Sheet metal baseboard duct tightly
seeled against floor and wall
Utility pipe
FIGURE 5 TYPICAL "BASEBOARD DUCT" INSTALLATION
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10.2.1. Baseboard Duct Installation Procedure
Two different types of baseboard duct were used at two different sites.
The first site (house #11) vos a small end row-house basement with a french
drain around the three external walls. The drain was connected to a sub-slab
drainage pipe, and the top of each block wall was covered with a caulked
soleplate. A brick veneer external wall stood on top of the basement wall, so
the \valls «ere not well closed at the top. In this case, the drain and cover
was used to carry the suction from the fan, and the walls were ventilated via
the holes drilled in the blocks.
The co\er was a commercial "7." channel made out of plastic and available
in 1.2 m ('1 feel) lengths. This is sold as an internal diain channel to place at
the foot of concrete block walls to trap water leaking out of the blocks at
floor level, and to lead it off to a drain. Inside and outside corners, joineis,
and plumbing connectors were available, but they would only glue the sections
together if the pieces were perfectly square. The workmen found it easiei to
form overlapping corners and caulk the gaps '.han to glue the sections.
Holers were drilled with an electric rotai \ impact drill and 12 mm (1/2")
bit at -10 mm from the floor m the mortar joint between each block. The
channel was placed o\ or the ftench drain at an angle of 60° to the flooi,
foinnng a baseboai d duct of triangular cross section, and secured to the floo:
and wall by screw anchois placed in previously drilled holes. A bead of
asplidltic sealant was placed on each surface beneath the co\ er edge to take up
surface irregularities. A "four inch" plastic drain pipe was connected to the
channel at one end, and i an out through a window to a 30 L/s centiifug.il fc-.ii.
The second site (house was a much larger house and needed lung
lengths of matei lal to c.o\ ei the drain. Joining the shot t lengths of plastic
channel was tiine-consumii.g, and the jo.ncd lengths were \ ei \ flexible .-nd
difficult to work \ ilh, so for tins house fla' sheet metal coveis weie f-ibi ict ted
loiallj in 3.3 n (10 feel) lengths. Lach co\ er was 2f»U mm (10") w.do, and the
edges weie folded, punched el interval-; of GOO inm, and set at angles of 30° and
60° lo the plane of the co\ er.
Holes weie di illed into each ea\ ity of the lowest course of blocks at GO
mm ft 01:1 the floor . ith .in electric t otai y impact hammer and 12 mm (1/2 inch)
dill! bit. 'I he co\ ers weie plated over the drain at an angle of GO degiees Lo
7 5
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the floor, so their edges were parallel to the wall and floor, and were attached
to the wall and floor with screw anchors inserted into previouslj drilled holes.
A bead of asphalt sealant was placed on each surface beneath the cover edge to
take up the suiface irregularities.
About 2.5 m (9 feet) of the french drain was concealed behind an
ornamental brick fireplace. The drain in this area was filled with concrete. A
wet concrete mix was flowed down a plastic tube slipped between the fireplace
brick facing and the basement wall. A fuither 11 m (36 feet) of dram was
inaccessible because a frame wall covered with tailboard had been built over it
to finish one end of the basement as a laundry room and a bathroom- A shower
stall unit also covered 1 m of the drain in the bathroom. As the wall sole plate
covered the drain reasonably tightly, it v>as decided not to cut off bottom of the
wall and install a cover, but to simply connect this part of the drain to the
ventilation duct, and Increase the fan capacity to compensate for the additional
leakage expected in this area. If it pro\ed necessary, this secton would be
dealt with in Phase 2 of this program.
The block voids at the top of the front and back basement walls were
partially closed by a large sillplate, which did not give enough room to insert
paper into the cavities so that they could be filled with cement or foam. The
sillplate was therefore sealed to the top of the wall v>ith wood strips coated
with caulking. The wood strips hart to be cut specially, for a stands d "2\1" whs
slightlv thicker than the sillplate and could riot be inserted between the top of
the wall and the underside of the joists. In areas where a wood strip could not
be inserted because of construction details, wiling or piping, a lajer of
expanding foam was placed on lop of the wall to close the voids.
The cover could not run round the basement m one continuous l inj, fo:
there were internal walls, a fireplace and an exterior door. It was installed js
four phvsically sepai ate sections, each exhausted by a "1 inch" lightweight
plastic drain pipe. These were connected to a headei pipe with a 50 I./s
centrifugal fan on each end. When the fans were turned on, i adon
concentrations were greatly reduced in the house.
10.2.2. Modifications to I" cist inrt Sv stems (1 r.d i\ idual Pi pes)
House was adjacent to house #8, and was of sinul'ii design ,ind
consli net ion, except that n seroudarj concrete block w.ill hid been const i urted
76
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on the floor to reinforce the uphill and rear walls which had cracked. Two
vertical steel beams tied to the floor joists provided additional support. A sub-
slab ventilation had been installed in house #3, but it had not made a large
enough reduction in radon concentrations to be considered effective.
A v&ll ventilation system was added to this house, similar to that used in
the adjacent house #8. An exhaust pipe was inserted in each basement wall,
with an additional pipe into the reinforcing vail at the rear of the house. The
original single-pipe sub-slab system was left in place, and tee'd into the wall
exhaust system. A single IOC L/s centrifugal fan exhausted the entire network.
The reinforced vail was two blocks thick on two sides of the basement, and
access to the top of this thick wull was se\erelj limited b> the floor joists.
Enclosure of the top of this v>all was all that could be managed, and this
requned much more carpentry than usual. Joints vere closed v ith caulking and
expanding foam, and the final result had very little leakage area. Good results
vere achieved.
House *2 had a sub-slab system 'nstalled, vhich had made a considerable
reduction in radon concentrations, but the results vere not fully satisfactory.
This house had been inspected b,\ a contractor for the DER v ho had made radon
"flux" measurements on the walls. The highest reading was obtained on the
basement vail adjacent to the gaiage, and it had been suggested that tins vas
an indication that the vail vas a major route of radon entr>. As a test of this,
the garage vail vas ventilated by connecting the existing sub-slab fan into the
vail (=2A). No significant change m radon concentration vas produced, even
though a smoke test showed that air floved from the house into the garage wall
through c \ try opening, eliminating the vail as a source.
Further smoke testing in this hcusc found air flowing into all the external
walls and into all accessible floor cracks. The only remaining route of radon
eritr> vas an int^r iul concrete block wall and fireplace sliucture, vlnch did not
ha\e a posit.\e airflov into it. Closing and \entilaiirig this structure would be a
m.ijoi task, and so it was l«'ft foi Phase 2.
10.2.T. L"\ nl' i.-it ioii
The success of vail plus sub-slab \ entilation (fi\e surface tieatinent) in
Phasi* 1 vas ambiguous. The results are suimnaiised in Table 11 belou. Tlie
su.nnier-tinie results indicated good performance at houses =9, ?3, ill, but only
77
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a marginal effect at house #2. This could have been because only one wall was
ventilated. Short-term measurements in the winter found that the cold leather
performance of all systems except house #3 had deteriorated markedly.
TABLE 11 SUMMARY OF PHASE 1 RESULTS ON SUB-SLAB + WALL SUCTION
RADON LEVELS WITH SYSTEM OFF RADON LEVELS WITH SYSTEM ON PERCENT
HOUSE (Bq/m1) RED1\7;'10N
NiO. T\ WAV
RANGE Alii 171. MEAN' RANGE ARITH.MEAN "
Baseboard duct o\er French >Iram
9 8 951 -17 575* 13 320+ 74 - 259* 185 99
11 ** "2 220* 555 - 1 036 777 ~65
Iiidi\ idual pipes in slab and ^alls
2A 3 25B -18 611* 8 806* 444 - 1 702* 1 036 88
(Only one wall ventilated)
3A 31 376 -54 575* 44 585* 37 - 74 37 99
* All measurements muiUed v.itb an asterisk here obtained during warm
weather months - July to August
** Insufficient data to determine range.
Vote: Post-mitigation levels rose during cold weather:
House 2 A rose to 13 505 - 54 575 Bq/in1
House 9 i oso to 296 -1 480 Bq/m3
These results ure based upon 1 to 2 days of hour\> Pylon nuitburcmenis in
the basement before and after the system was activated.
10.3. PHASE 2 - C.ENEIfAJ.
Based the Phase ! experience with separate wall ventilation and sub-slab
\entilaticn systems, it was felt that combined wall/flooi systems would be
needed to effecti\el> dc-ul uit'a the lusher lev el liout,oti (> 1 KBij/m5). Further
testing of combined s>stims was planned for Phase 2 to determine the important
parameteis, and to optimise the design. Improvements «ere planned for the
hjstems at house s9 and *11, and a nev system was plam.ed for hnuse ?2.
Houses =7 and =0, vhich had unsuccessful wall ventilation systems, diirl -1
which had an unsuccessful sub-slab \ entilation sv stem would all be converted to
wait plus sub-slab svstems.
78
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The owner at house #11 did not wish further work to be done, and this
house was therefore dropped from the program.
No new Phase 2 houses were selected for wall plus sub-slab ventilation as a
primary mitigation measure. As it was clearly the highest cost option, it would
be installed in houses only if less costly mitigation systems were ineffpctive.
10.3.1. 1 nstallation Procedure
The new systems installed at house #2 and #1 uere baseboard duct systems,
similar to those installed at houses #9, £11. Ilchever, there was 110 frerich
drain in houses #1, #2, only a shrinkage crock at the vxall/floor joint. The
baseboat d duct therefore primarily provided wall ventilation with a smaller sub-
slab ventilation component. The floor at house £1 had been poured in seveial
sections, and the peripheral crack was smaller than at house ?2. The oveiall
system design was similar at each place, the walls hould be closed at the top
and multiple openings hould be drilled at the bottom, ana a cover would be
placed over the wall/floor joint and the openings in the walls. The cover would
be exhausted, ventilating the walls and the sub-slab space via the wall/floor
joint and the wall/footing openings.
A few test holes were drilled through the floor slab at each house in
aifvis that hould be beneath the cover to see if the communication to the sub-
slab fill could be improved. In each case the drill struck the footing without
passing through a signit.cant layer of fill, so this idea has given up.
The baseboard cover design used at house #2 urs the same as that used at
house £9. The houses were similar in si/.e, but at house ~2 the basement halls
were painted, and the sill plate has caulked to the top oi" the basement wall,
'i he ait flow's out of the walls here expected to be lower than at house #9, so
the same si^e of duct was expected to he satisfactory. The cover could not be
installed in one continuous loop, for- the basement halls heie witeri upted b,\
Uo dooi s to outside and an inlet rial v»ali which included a fireplace. 1 he
cover has llierefoi e installed in tho separate sections each \%ith its oun
100 L/s centrifuj ol fan. One section was extended to ventilate the internal
hall.
The u'ver design at house #1 has a lare"e rectangulai duct 300 mm high
and 80 mm wide fabricated loyally from sheet metal. The halls at this house
here of porous cinder block and had many openings, so <1 has expected that
79
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large airflow 3 would be drawn from the walls. The duct had about four times
the cross-section af the ducts used at houses £2 arid s9 to decrease the flou
velocity irid the pressure Iossps in the duct. The basement walls were painted
with waterproofing paint to increase their airtightiiess. The duct was originally
installed as a "C" ring with only one interruption at the exterior basement door
and with one 100 L's fan nt one end of the house. This did not produce any
airflow into the wall at the far end of the duct, and so the duct was made into
a continuous loop b\ running a duct around the door frame, and a second
100 L/s fan was added at the opposite end of the house.
The sj stem at house was extended to eo\ or all of the fiench dram,
except for u short 2.'f m bed ion behind a basement bathroom wall and shower
stall. The 50 L/s fans were replaced by 100 L/s units.
Initial testing v.as done at these three houses w ith fans exhausting the
ducting. This led to significant depressurization of the house, as shown Ijv
smoking fireplaces mid stoxes. The exhaust fans at these houses wore all
replaced with wall mounted 150 i./s pressure fans.
At houses -7 and -6, wall "ventilation system was extended to act as a
combined wall and floor s\stem. The piocedure used ;ri these louses was to
coie drill a hole in the floor beneath the wall exhaust pipe and extend the pipe
into the hole. The sane fan then exhausted both the walls and the sub-slab
space.
10.3.2. Ex filiation
The results from these Phase 2 nnd Phase 3 installations ru e summarised in
Table 12 below.
One end of Hie basement cit house was used as a stot e room ar.d there
was a workshop with n firi'shed walls and floor. In pi ep.n at ion for the duct
installation, the stot ed natoruils were removed and the walls cut awa> to expose
the wall/floor joint. The sub-slab eOiausL \ otein was rurunng com ealed end wall of the house was into the house. Tins
indicated th?jt ihei e must he a low permeability zone in the sub-slab ia> er of
crushed stone that was preventing suction from reaching to this end of the
house. \ multiple pom I floor e\haust .sytom h ould hn\(* o\ eri'i.ine this.
80
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TABLF 12 SUMMARY OF PHASE 2 AND 3 RESULTS FOR SUB-SLAB + WALL SUCTION
HOUSE
NO.
RADON LEVELS WITH SYSTEM OFF
(nq/m •»)
RADON LEVELS WITH SYSTEM ON
(Bq/a3)
RANGE
ARITH.MEAN
RANGE
Baseboaixi duct
1A 4 662 - 7 363* 5 957*
IB 4 662 - 7 363* 5 957*
2B 3 256 - 18 611* 8 806*
9A 8 954 - 19 575* 13 320*
Individual pipes in slab ar>d walls
6-\ 851 - 3 626* 2 294*
7C 5 772 -23 162 11 874
20B 5 476 -25 752 * 10 134*
1 665 - 3 8S3
111 - 259
74 - 222
111 - 370
555 - I 924
592 - 1 739
ARITH.MF-AN
M -
2 812
185
148
259
221
962
148
PERCENT
REDUCTION
IN MEAN
53
97
98
98
47
93
99
* All measurements marked with an asterisk were obtained during warm
weather - July to August.
These results are based upuii 2 lo 4 days of hourly Pylon measurements in
the basement before and after the s\ stem i>js activated.
The triangular duct was installed without p:-obies, and the duel there was connected to
the f.iii by a square dut t that ran rounu one of the doors. Then' was a
dispropurtionate air leakage into this duct at the transition fittings, and the gain
in performance (if anj ) from the short duct was probshly not worth the cost.
Thi' top cuiiisc of blocks were remo\ed frr,a the internal wall and
fireplace to gain access to the voids, which were then filled with mortar to
increase the ait tightness of the interior wall. The blocks were then replaced.
The fueplace flue sti ui Lure in'enor could not he accessed, so there was in
untreated an leakage path there.
Operation of the sj stcn plated all the walls ar.d the sub-slab fill undet
suction relative to the house as slioun by smoke ^tick testing, and ga\ o low
radon coriri ntrations. \ir leakage into the sj stein was large enough lo cause
the b.i.-ii-rr jut fireplace to backdi.ift. The 100 I,/s exhaust fans were leplaced
with 150 1,/s pressure fans, which cm ed this problem, and equally good
perfornianre was a
-------
At house £9, the trsa-<£ular duct was extended beu replaced with tuo
wall mounted square sheet /vuetal ducts connected to the lrit^.gular duct in two
places. The wall closures carried out m Phase 1 were checked, and improved by
additional caulking or expanding foam.
Operation of the syiAfa placed all the v>hIIs and 5&<# sub-slab space
generally under suction relative to the house, as shown smoke sticK tiists,
and reduced radon concenliretions. Ilouevet, air leakage skVj I ho system w.is
large enough to cause the bas.jmont wood stove to backdrfc-1: and smoke. The
fans were replaced with 150 L/s pressure fans, which cur«>i this pioblem, and
satisfactory perfoi mance w«ai obtained.
At house ?1, the 2 .uJtial 100 L/s fans were too s>n.ill to pioduce a
significant depress!irszaltcm ut the walls, for leakage ariits uere much larger
than anticipated. A major ii.-«^v.essible opening was aro'JutS ifte bast-n:"nt stove
flue, which parsed out thr-cugrh a hole in the block \.a!! So an external blo~k
chimney. The hole in the ou-ieer leaf of the wall was much jL&jjSVr than ti:e flue
pipe, and could not be rearfted to close it without the chimney.
Much of the capacity of t'.-f fan at this end of the how so was taken up in
drawing air thiough this uj»*-r.jng. Part oT the front wa;» af 4is house i».is of
bri.-k veneer, and there wof 'i gap between the bi ick ar,-Ji \h<- header boaid.
This was filled w.th e\pandsfLj foam injected through 100 ts.o) HXiametci holes cut
in the header boat iir diawn fi uii'
the basement caused the st*o backdraft, so before the wc-re reversed to
piessurise the basemen'-, i'ltio-inl plastic 'Z' ducting was pl^-od over all the
wall/floor joints to prevent &ct! -tas from being forced out oT Jiicso opemi gs. A
test u"-mg two 50 l./s in press"; re mci eased ladon concentre*)~ns, and soil gas
was foi ced out of floor jo.i ts ar.d .small floor openings. Thewe ut-re closed, and
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the small fans replaced w ith 150 L/s wall mounted pressure fans, which gave
higher system pressures and flows, arid low radon concentrations (house £2B).
Shortly after this work was completed the owner sold the site, and
removed the house superstructure to a new basement constructed on a new site
several km distant. The old basement was demolished in the moving process, so
no long-term vintei-time measurements could be made.
The performance of the wall ventilation system at house -7 had been
impioved by work to increase the air tightness of the floor, which indicated
that the size of the random connections between the walls and the soil were
too sma>l (and the wall suction too low) to effectivel.\ depressuri/e the sub-slab
space. Extending the wall exhaust pipes into the sub-slab fill produced a major
reduction in radon concentrations.
The 3 wall exhaust pipes in the unfinished half of the basement at house
£6 were extended into the sub-slab fill. The second isolated exhaust fari
treating the finished basement wall adjare-nt to the gaiage was turned off. A
major reduction in tadoii concentrations was obtained, even though theie had
been no work to close the construction joint between the two halves of the
basf.i.ient slab, and the wall ventilation had been reduced.
The success with lelatively little extra effoi t of these two multipoint wall
plus sub-slab \ eritilation s\stems, coinpaied to the major efforts icquired to
achieve computable success with the baseboard duel sv steins, suggested that t he
multipoint system was the moi e practical of the two. Performance was bettei
foi the suction was applied directly to the sub-slab fill rather than induectlv \ la
random openings in the wall footing, resulting in bettei control of flooi entry
routes, which was more i.ecessai v than had it had seemed in Phase 1.
10.1. PHXSi: 5 - CLM'U \L
No new houses weie selected fo: wall plus sub-ulab ventilation as the initial
mitigation nethod in Phase 1. If an) of the Phase 3 coin i ete block basement
houses where sub-slab s) stems were to be installed did not give gcod lesulls,
then the> would be converted to wall plus sub-slab sj stems. Modifications were
made to the system at house ?7 t < > see what ratio of wl.11 to sub-slab ventilation
give the best results. House ?20, w hei e a sub-slab sv stem had been installed ill
I'hfise 2, was r.mvei led lo a wall plus sub-slab sv stem, for tliei e was a known
t adon supplv \ vi the walls. House = (> was roip erted to a sub-slab onlv sv stein.
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10.4.1. Evaluation
Dampers were installed in the wall exhaust pipes at house #7, and the
ratio of air drawn from the walls to air drawn from .lie sub-sLab fill varied.
Closing the dampers increased the suction in the floor pipes, and low radon
concentrations were obtained with the wall dampers fully closed. The system
was now operating essentially as pure sub-slab sj stem, with a very small wall
ventilation flow.
The wall exhaust pipes uere removed at house #6, and the system re-
installed as a sub-slab system with closure of floor openings. An exhaust pipe
was not installed in the finished half of the basement, so only three exhaust
pipes were used. Low radon concentrations v.ere obtained.
The owners of house £20 added an extension to the house oxer the summer,
with a sub-slab ventilation sjstem consisting of a loop of perforated dram tile
beneath the paved crawlspace slab. The system tested in this house consis'ed
not only of a wall ventilation phis sub-slab system in the oiiginal basement, but
also the extension sub-slat> system (#2UB). rhefce wcic ultimately connected to
the : line 150 L/s exhaust fan. It was found that it was necessary to opei-ite
both systems to achieve low i adon concentrations i.i the basement, bat that the
perfoi rrauce did not vhi j as the crawl space system exhaust flow was varied.
Disconnecting the suction pipes from the walls and running as a pu»*e sub-s!'ib
system (=20C) appeared to give a s-nall increase in basement iado.1
concentiat ions. All measui ements in this house were complicated by the
presence of high dissolved radon concentrations in the well water, which cuised
large increases in the an borne radon concentrations whi never wat.tr was used.
10.5. 0\FP\ll. LV\LU\U0\ OF U \LL PIUS SllH-SI.\H \ FN T I I.ATK >\
Al'hough the wall plus sub-sl'ib ventilation sy ste.us effectively i educed the
radon roncenli ations, the general conclusion was that the clabai.ito wall/floo,
baseboaid duct systems u:-cd in the fn st house» wen; piobably ihiipi essfirj. 'I 1 e
use of a perimeter multiple point sub-slab exhaust s,\ stein with high 'w.tion f ni
was able to reduce ifidon entry through 1 }i o walls without a separate will
ventilation system. Presumably , although the sell permeabilit •, beneath the
foundations was low, it was still high enough for suctii n to pass underneath the
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footings and depressurize the soil in the vicinity of the interior wall/footing
joint.
The preferred solution for n french drain was not to place a cover over it,
'but to fill it with mortar over a layer of gravel. Thit, would decrease the air
leakage area, ana «%till allow water to drain from the walls. A sub-slab
ventilation system could then be installed.
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SECTION 11.
EXPERIENCE WITH HOUSE VENTILATION
11.1. PHASE 1 - GENERAL
House -18 had block walls open at the top, and an open "french drain"
round the basement. Despite these large soil connections, premitigation
measurciventi found only moderately elevated and highly variable radon
concentrations averaging 600 Bq/m3 (15 pCi/L). Tnis suggested that the radon
suppl\ rate uas relatively low, and that increasing the basement ventilation rate
might be an effecti\ e mitigation measure in this case.
11.1.1. Installation Procedure
The house vas heated by an oil-fired hot water system, and a recuperator
was installed on the boiler chimney. When the oil-burner operated, a small fan
ble\s basement air through the recuperator to extract heat from the hot
chimnej gasses. As with any combustion appliance, the flou of combustion
gasses and draft air up the furnace flue v%ould tend to lo\\er the pressure in
the basement, and draw iri soil g.is.
To reduce the depressurization a fresh-air supply duct \%as attached to the
inlel side of the recuperator. When the oil fui nace operated, the recuperator
fan uould draw in exterior air from outside, heat it, and then supplj it to the
basement to replace some of the combustion and draft air that uas leaving.
Even Vvhen the fan was not operating, the duct wold still provide some
\entilatiun to the basement. This would reduce the pressure differential
between the basement and the ground, decrease the radon supply rate, and the
fresh air would also dilute the radon that did enter.
11.1.2. E\ aluation
As the sjsteiii uould be most effectise in winter months uhen the burner
feould inn frequently, measurements uerc delayed until then.
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11.2. PHASE 2 - GENERAL
Short term wintertime measurements in house #18 found that the radon
concentrations in the basement were similar to those measured by the DER the
previous winter. Thus the increased airflow of 15 L/s into the basement when
the furnace burner was running had not significantly reduced the radon
concentration. The additional airflow was clearly insufficient. It was decided to
install a Heat Recovery Ventilator (HRV) in this house, to provide a higher and
continuous ventilation rate. In addition, HRV vendors had recently reported
substantial reductions in houses similar to house #18, large enough to reduce
concentrations to the 150 Bq/m3 level. These reductions were larger than might
be expected from dilution alone, and it was therefore desired to test HRV's as a
potential solution for houses with radon concentrations in the <800 Bq/m3 range.
The sump \entilation system installed at house *17 had not made any
significant reduction in radon concentration, and had been removed. This house
was e\tensi\ely finished in the basement, had a number of unique construction
features, and relatively low radon concentrations. It was decided to install a
HRV there, as it would be the lowest cost mitigation measure.
11.2.1. Installation Procedure for HRV's
A local contractor who had installed a number of HRV's for radon contiol
was asked to design and install a HRV mitigation system at each house. His
recommendation uas a split system, with tempered fresh air discharged upstairs
through floor ducts, and the exhaust air taken directly from the basement.
This system \»as installed at house £18 and house #17.
11.2.2. Heat Recovery Ventilators
The same modal of HRV was used at each house. This unit uses a rotating
vheel made of a coiled flat plastic strip as the heat exchange medium, and has
a nominal air deliverj rate of 100 L/s, and an actual delherj between 45 to
70 L/s depending on the fan speed setting and the ducting. There is a
fiberglass filter in the inlet airstream, and a foam filter on the exhaust
aii'stream to protect the nai row air passages thiough the wheel fiom an borne
dust.
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11.2.3. Evaluation
The results of both the Phase 2 and the Phase 3 measui ements are shown
in Table 13 below.
The performance of the two systems was similar. The radon concentration
in the upstairs portion of the house was reduced to a satisfactory level, but the
concentrations in the basement vere virtually unaffected by system operation
with this duct configuration. This suggested that the mode of action in these
hot-water healed houses was that the upstairs air supply slightly decreased the
pressure differential relative to the basement, which decreased the amount of
basement air that found its v. ay upstairs, and so decreased the upstairs radon
concentration. The large differences in radon concentration that here seen in
these houses can be attributed directly to the hot-water heating. Forced air
healing ducts provide good connections from floor to floor. On the other hand,
either the exhaust from the basement was insufficient to change the radon
concentration, or else it induced a compensatory increase in radon supply, so the
basement concentrations were unaffected.
The HRV installer and the manufacturer suggested that basement
concentrations might be ieduced by changing to a balanced basement ventilation
system, v,here outside air \»as discharged into one end of the basement and the
exhaust removed from the other end. This was tested at house ^17, and it v*as
found that although the basement concentrations were lower with this system,
the concentrations upstairs were not as low as when the split system was in
use.
The system at house *17 has modified to allow easy adjustment of the air
deh\ ery and exhaust. Uampered ducti> were added to allow a variable air
discharge into the basement, and the amount of air exhausted from the
basement.
11.3. PHASE 3 - GENERAL
The modifications to the system at house sl7 uere not tested in l'hase 2
as they were completed after the weather was warm and windows were open.
The sj stem at house ?18 whs also modified to a balanced basement ventilation
system, and both houses were tested in cold weather in Phase 3. A thud HRV
was installed at house *28, for the sump \entilation s,\ stein installed theie in
Phase 2 was not effective. This hou^e was a good candidate for a l!K\
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installation, for the radon concentrations were only moderately elevated, and
the basement was extensively finished.
11.3.1. Installation Procedure
The same local contractor who had installed the previous HRV's was asked
to design and install a HRV mitigation system at house #28. Most of the
basement at this house was finished as a family room, and his recommendation
was to install the same type of rotary wheel HRV as pre\ iously used, but in a
balanced basement ventilation configuration. The HRV was placed in and
exhausted from the unfinished laundry room, and deli\eied tempered fresh air
into the recreation room through a grille placed in the dividing wall. The
recreation room uas a majoi living area, so the focus of the installation v»as to
reduce radon concentrations there.
11.3.2. Evaluation
The results of the Phase 2 and the Phase 3 tests on the HRV's are shoun
in Table 13 belovw
The HRV at house #18 was modified to operate as a balanced basement
ventilation system for a test, and the radon concentrations in the basement
remained essentially the same as when it was operated in the split mode with
all fiesh air discharged upstairs, and basement exhaust. Upstairs concentrations
were always, lo^er than in the basement, but the lowest concentrations v. ere
achieved with upstairs fresh air discharge. The ventilation rate and inter-floor
transfer rates v.ere measured by passive PFT detectors during this test. The
accuiacj of the measurements v.as low, due to the short exposure duration, but
they did indicate that both the basement and main floor ventilation rates weie
high, arid greater than the IIUV flov.s. The net transfer rate of basement air to
the mam floor v>as only a fraction of the upstairs ventilation rate, and the
transfer rate decreased vhen fiesh air v%as discharged on the main floor, rathei
than in the basement. This confirmed the general pi<_tuie deduced fiom the
radon nioasm ements.
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TABLE 13 SUMMARY OF PHASE 2 AND 3 RESULTS KITH HRV's
HRV
CONFIGURATION
BASEMENT RESULTS
MEAN Rn (Bq/m3) %
HRV ON OFF REDUCTION
UPSTAIRS RESULTS
MEAN Rn (Bq/m1) %
HRV ON OFF REDUCTION
70 L/s from basement
90 L/s fresh air to
upstairs
75 L/s from basement;
75 L/s fresh air to
upstairs
70 L/s from basement;
70 L/s fiesh air to
basement
55 L/s from basement;
33 L/s fresh air to
basement
60 L/s from basement;
20 L/s fresh air to
upstairs; 60 L/s fresh
air into basement
95 L/s from basement;
62 L/s fresh air
upstairs
75 L/s from basement
65 L/s fresh air to
upstairs
75 L/s from basement;
65 L/s fresh aj r to
upstairs
95 L/s from basement;
85 L/s fresh air to
basement
20 L/s from basement;
80 L/s fresh air to
basement
HOUSE 17A
1 776 2 146 -19
2 701
2 701
1 480
1 702
1 702
HOUSE 18A
518 481
518
851
851
333
37
444 70
518 38
481 45
HOUSE 28A
592 333 41
444
1 776 1 406 21 444
?03
703
296
31 296
333
333
333
74 81
4 82
135
259
75
62
74
56 81
92 72
148 60
259 15
The HRV at house #17 uas tested as n simple ventilation supply fan by
closing the stale air exhaust damper and diverting the airflow back into the
basement. Fqual amounts of fresh air here delivered to the upstairs and to I he
h.iboment. The dampers \*ere then returned to the noi mul position to opeiute
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with exhaust from the basement. The fresh air supply was slightly higher under
these conditions. Concentrations upstairs were always lower than in the
basement, and both upstairs and basement radon concentrations were slightly
lower when the system was run as a HRV. The ventilation rate and inter-floor
transfer rates were measured by passive PKT detectors during this test. The
accuracy of the measurements was low, due to the short exposure duration, but
they did indicate that the ventilation rate upstairs was much higher than the
forced air supply, but the basement ventilation rate was comparable. The inter-
floor transfer rate was low, and decreased when the HRV exhausted from the
basement. This confirmed the general picture deduced from the radon
measui ements.
The dampers were adjusted to decrease the fraction of air sent to upstairs
to 25%, and this lead to lower radon concentrations in the basement and higher
radon concentrations upstairs.
At house #28, short term measurements found that operation of the HRV
reduced radon concentrations in the basement from about 600 to 370 Bq/m3. The
concentration upstairs remained at about 300 Bq/m3, regardless of whether the
HRV was running or not. This suggested that there was a separate radon supply
to the upstairs, for if all the radon that reached the upstairs came from the
basement, the concentration upstairs should have decreased as well. Large
transfers between upstairs and downstairs were expected in this house, for it
had a forced air heating system, and operation of the fan would tiansfcr air
from the basement to upstairs.
11.1. OVERALL EVALUATION OF INCREASED VENTILATION
The results obtained with HRV's suggest that two separate factors were at
work in determining the reduction in radon concentration obtained in a house
zone. The first was that fresh air forced into the upstairs zone could decrease
the flow of radon bearing air from the basement, and by reducing the radon
supply could reduce the radon concentrations b> much more than the incic-tse in
the zone ventilation rate. The second factor was the increase in \entilation rate
caused by the fresh air forced into the zone. This was dependent on the natural
¦ventilation rate in the zone, which could be higher than the HRV flow.
Although these urnts were installed by an experienced cnnt r.ictoi , only the
inlet air duct was insulated to piv\cnt the cold outside air fiom pit I11115 up heM
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on its way to the HRV. The stale air e thaust duct was not insulated, and so
this cooled air was able to recover a l'irge portion of the heat it had given up
to warm the incoming fresh air. The heat recovery efficiency of the installation
was therefore much lower than the HRV efficiency. Economic justifications
based on significant heat recovery efficiencies are likely to be in erior unless
contractors pay attention to the thermal performance as well as the ventilation
performance of the system.
Measurements of ventilation and inter-floor transfer flows are needed to
predict the performance of HRV's. Although increasing the ventilation rate is
simple in principle, the air circulations in a house are more complex than it
appears at first. If better performance is to be achieved than just that given by
simple dilution, the changes produced in the flow dynamics throughout the house,
and the possible effect on the entry rate of soil gas must be understood.
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SECTION 12.
EXPERIENCE WITH RADON REMOVAL FROM WELL WATER
12.1. PHASE 2 - GENERAL
By the end of Phase 2, average radon concentrations in house #2 had been
reduced to a level where it was apparent that the radon supply via the well
water (thought to have a concentration of about 2.5 MBq/in3 - 67 000 pCi/L)
was comparable to the supply via soil gas entry. The DER had also identified a
house, house #30, where the radon concentration in water (11.5 MBq/m3-
310 000 pCi/L) was the highest that they had measured, and was probably
responsible for the elevated radon concentrations in that house. It was decided
to place radon removal units on the water supplies of these houses to evaluate
their efficiency and determine what problems they might cause in practice.
12.1.1. Installation Procedure
Activated carbon was selected as the removal method for it had been used
successfully in other high ladon in water areas such as Maine. The unit
consists of a pressure tank containing activated carbon installed between the
well pump and the pressure control tank. All the water that enters tho hov..se
passes through the tank, and the mdon in the water is adsorbed to the carbon
surface.
Tv>o different suppliers were used. The first came from a specialist firm
in Maine, and contained 60 L of coconut charcoal selected for radon removal.
This was installed at house #30, where the radon concentrations were the
highest.
The second unit came from a local water purification supplier, and
contained 60 L of charcoal of unknown origin, which had probably been selected
for organic removal. This was installed at House £2.
12.1.2. E\ aluation
Both units initially had \eij lugh ladon lemoval efficiencies (ch, 99%),
reduced the radon concentrations in the uater, and eliminated the peaks in 'lie
house radon concentrations associated v»ith watei use. However, large amounts
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of radon and its progeny were stored on the carbon, and the gamma radiation
field in the house was increased considerably in the region of the unit.
12.2. PHASE 3 - GENERAL
The increased radiation fields concerned the householders, and so shielding
was installed ax-ound the tanks in Phase 3.
12.2.1. Installation Procedure
Theoretical calculations showed that at least 10 mm of lead would be
needed around the most active tank (house #30), and a lest by u rapping the
tank in two layers of 1.5 mm thick lead sheeting confirmed this. \ lead shield
would ha\ e to be specially fabricated, and would be expensive, so a connete
block shielding structure was built around the tank in each of houses c2, -30.
The walls of the structuie were of four inch block, and a concrete patio
stone uas used to cover the top. These structures produced a satisfactory
reduction in radiation field at both locations.
After the shielding had been installed, there was a new baby at house 430,
and the water consumption increased. The radiation field increased
correspondingly, and additional shielding was required. The space between the
inside wall of the block structuie and the tank \%as filled v*ith sand,
approximately doubling the mass of shielding material. This reduced the
radiation field to a level lower than that given by the original shielding.
12.2.2. Evaluat ion
The radon removal efficiency of the carbon was initially hign, m the
region of 99% for the specialist charcoal, and 95% for the standard chaicoal.
Over a period of eight months, 't decreased, and stabilised at around 93% for
the high efficiencj charcoal (house r30), and 75% for the other chaicoal at
house (=2). These reductions vere sufficient to reduce the airborne radon
concentration resulting from v»ater use to a low level.
The concrete block shield v.as not sufficient to deal \vith the combination
of high radon concentration and high water use, and sand had to be placed in
the enclosure to increase the shielding mass. Given '-his, an alternative and
cheaper shielding method \%ould ha\e been to use a lai ge 60 cm diameter
9-1
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lightweight impregnated paper tube (Sonnotube) around the tank, and fill this
with sand.
12.3. OVERALL EVALUATION OF RADON1 REMOVAL FROM WATER
There was a significant difference in the raden removal efficiency of
different carbons, but both units performed well, reducing the contribution from
waterborne radon to a low level.
The major problem \%ith these radon removal units is the radiation field
from the radon collected or. the carbon. The greater the need for a radon-in-
water removal unit, le high radon concentrations in water find use of large
volumes of vater, the higher this radiation field will be. A lightweight paper
tube filled with sand \%ould provide relatively cheap shielding. In addition, after
the carbon has been in use for several years, it may have accumulated encugh
long-lived radon progeny (210Pb) for the carbon to qualify as a legally
radioactive. Current regulations would require this to be disposed of in a
licenced iadioacti\e waste storage facility, at high cost.
Iri view of these difficulties, a better long term solution might be to use a
.stripping unit for radon removal. Tins would remove the radon from the water
as it was used, and discharge it outside the house. There would be no large
radiation source in the bAs>cmerit requiring shielding, and no radioactive v»aste
disposal pJobi«m. Howt^ei, thr*rr- ure still problems vith the stripper, for
domestic sized radon stripping units fire not as commerrlall.v developed as carbon
adsorption units, and comparable performance at a comparable price may not be
available.
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SECTION 13.
TERRESTRIAL RADIATION MEASUREMENTS
13.1. EQUIPMENT
Gamma radiation measurements '/ere made at mitigation houses and in the
area generally with a 5-channel Nr.I scintillation meter which had been
calibrated at the Depaitment of Energy, Mines and Resources radioactive test
pads in Ottawa. The exposure rate from cosmic rays indicated on this
instrument is appro.ximately 2 uR/h. When the threshold is set so that the
instrument responds only to gamrna-rays above 400 keV, the count ratr; in a
terrestrial radiation field is, approximately proportional to the total e^.posure
rate.
13.2. GENERAL
Radiation fields vere significantly higher in the vicinity of these houses
than in the general area. The radiation field in the house and on the site is
noted in the description of each house. Table A-13 summarises the measured
gamma radiation levels at each house.
In the Bo; ei town area, the terrestrial exposure rates along the main roads
- which run in \allejs - ranged from 4 to 6 uR/h. In contrast, al! the
mitigation houses are located on high giound, where the exposure rales ranged
from 7 to 12 uR/h, with significant changes in exposure rate in short distances.
For example,near Boyertown,the e\posure rale along Indian Road, which runs
along the top of a ridge, varied from 5 to 6 uR/h at Applewood Road, rose to 7
to 8 uR/h at the junction with Funk Road, and reached a high of 10 uR/h on
Knoll Circle. On Hillcrest which is on a second ridge just U*o hundred
metres, awaj from hnoll Circle, the exposure rate uas only about 6 ulJ/h.
13.3. VARI \TIOM WITH Dr PTH
The soil gamma activity inci cased ^ ith depth. Part of the variability of
the radiation field at a house site was evidentlj due to higher nctp ily
excavated material having been dumped on the lower portion of the site. \t
one house (?9) a shimming pool was under construction, v»hieh enabled
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measurements tc i>e made of the distribution of activity with depth. Fill from
the house excavation covered t*»e site to a depth 3f 30 cm, and gave 24 uR/h on
contact. The original surface soil beneath this la>er gave about 1J to 16 uR/h,
but a layer of rocks near the bottom of the excavation had fields of 30 uR/h,
with one rock reuching -10 uR/h on contact.
Granite bediock was exposed on a road cut near house »9. The general
activity was about 6 uR/h on contact, but a localized 2 m v%ide band of more
highly fractured gianite with 24 uR/h on contact was visible. The activity of
the hot spot was estimated at 2.7 pCi/g "*Th, 6 pCi/g "SU, and 10 pCi/g alS-
from the ratio of the counts in the channels of the meter. The granite henewth
house £9 must have an even higher activity zone to produce the more active
rocks found in the swimming pool excavation.
13.4. RADON- PRODUCTION" RATE
Rock fragments were collected from both the host granite and the higher
activity zone, and the radon production rate v.as measured at 0.13 pCi'g and
0.48 pCi/g of emanating radium (emRa) for host rork and active zosie
respectively. The radon production rates were also measured for a soil sample
from the swimming pool esravation at house £9, and for a sanipie collected from
a hillLop building site of lo\ er gamma activity. The values uer-j l.i pCi/g emRa
for the house £9 sample, and 0.24 pCi/g c-ml.'a foi the building si'^ Thp
emanating radium content of the house r?9 soil is high, and is comparable t*>
that found in reclaimed Florida phosphate lands, which are themselves among
thr: highest activity soils in the USA.
t3.5. COMMENT
The area was not glaciated m the tecrnt geological past, so the local soil
is derived entirely by weatheiing of the underlying rocks. The soil in Ihe
vallej s is derived mainly from the lower fctivit'v sandstones tnat form their
floor, where.is the soil on the hilltops is derived mainly from granites. Given
the lai ge variations observed iri the gamma activity of the p.iront snii-Jslones 'nid
granites, the variations in soil activity from site to site are not sni prising. The
surface materials ma.\ be lower in activity th.:ri the base rocks from ulnch thyj"
are derived as the result of awns of weathering. If this is gerieiallv Ine case,
tier, sui face radiation measure merits. will be a poor indicator of the i^doii
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potential of a given site, although they may be useful as a general indicator
locally increased radon potential.
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SECTION 14.
QUALITY CONTROL AND QUALITY ASSURANCE
14.1. QUALITY ASSURANCE PLAN
The Quality Assurance Project Plan (QAPP) was issued on 25 October
198^, anj modified in January 19?T>, ar.d De<-«-iui»r:r 1986 to reflect changes m
emphasis in the program. The QAPP covered Quality Assurance Objectr.es,
instrument calibration, sampling, and control chocks. A brief re\ ie\» of these
topics is included in this section.
14.2. TRACK ETCH DETECTORS
Calibration and quality control of Track Etch detectors is performed b\
the manufacturer, Terradex. As an independent check on calibration, ten detec-
tors from each of the two batches used v>ere ex-posed in the EML radon
chamber at the same time as detectors here deployed in the field, and a similar
number of detectors were retained to act as unexposed controls. They uere
returned 'blind' to the processing laboratory.
11.2.1. Calibration Checks
Detectors were exposed in the EML i adon chamber in December 1985 and
in December 1986. The first batch uas exposed to 1590 pCi.d/L, and the axerage
exposure reported was 1428 pCi.d/L (10% low). The analytical uncertaintx on
each measurement was reported at 160 pCi.d/l.. The standard deviation of all
the measui ements about the mean was 228 pCi.d/L (16%).
The second batch was exposed to 423 pCi.d/L, and the n\ erage exposure
reported \.as 36-1 pCi.d/L (11.low). One outlier with n repotted value of 1 190
pCi.d/1 + 200 pCi.d/I. was rejected from our analysis. The anal> tical unce.' t unt\
on each measurement was reported at 58 pCi.d/L, hi1' the standard de\ lotion of
all the measurements about the mean uas 5U pC'i.d/I. ,12*).
As the difference between the reported and actual exposures \»as less than
tv. ice the standard deviation of the measurements, the reported exposuir-s m the
houses \M-re not (.Directed.
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14.2.2. Zero Checks
The average exposure reported for the unexposed detectors for the first
batch was 15 pCi.d/L, with an analytical uncertainty of 16 pCi.d/L. The average
exposure reported for the second batch was 2 pCud/L, with an analytical uncer-
tain^ of 4 pCi.d/L.
These exposures were not large enough for the reported exposures in the
houses to require correction.
14.2.3. Field Quaht.\ Control
The EPA Protocol for Indoor Measurements suggested that 10% of the
measurements should be made in duplicate. This, was iiot felt udequate for this
program, and 100% of the measurements \sere made in triplicate.
Detectors we J e exposed taped together in groups of three to detect
outliers. The average radon concentration at a location uas calculated as the
average of the detector readings. At the low radon concentrations found in
these houses after mitigation, the standard deviation of the group was usually
about 30%, or 1.5 pCi/L. Outliers were rejected if this would reduce the
standard deviation of the group to less than 2 pCi/L or to less than 10%.
Three outliers were detected in 224 detectors exposed in the field, and in 1 of
the 20 calibration detectors exposed at the EMI..
14.2.1. Completeness
Results were received for all of the 264 detectors sent to Terradex for
piocessing. Si\ detectors could not be found at one house. It is believed that
they were collected in error by another group making measui eraents with
Terradox detectors in the area. Si\ detectoi s wore issued lo one homeowner
v ho had diopped out of the progiam, but h<_ did not return them.
1 1.2.5. (jualit > Asm n a rice Objectives and l'ei forinanco
The Accural.\ objective for Track Etch ineasui einents inaj not have been
achieved, foi the manufacture!'s calibration is apparently ) 0% to 15% louer than
that deiived fiom Hie E^U- exposures. The difference is not significant foi the
lov> post-inil igation exposures of a few hundicd pCi.d/L, for the major soutce of
uni crtaiutv m those mcasu i i;mfiit? is the anal \ t k'il variability betueen detectors.
100
-------
QAPP Goals
Actual Performance
PRECISION
2 pCi/L (30%)
2 pCi/L (30%)
ACCURACY
10%
<15%
COMPLETENESS
100%
100%
14.3. AB-5 RADON MONITORS
The AB-5 monitors used in this program were calibrated at 12 month
intervals at the DOE Environmental Measurements Laboratory in New York. A
specially modified cell containing a small emanating radium source (Check Cell)
with a nominal count rate of 2003 cpm, v.ns used to set the opttmuiri high
voltage and discriminator setting for radon measurements. To minimise the
backgiound count rate, the high voltage was set just abo\e the knee,
appi o\imatel.\ 60 volts onto the plateau.
Simultaneous measurements over 16 to 24 hours were made v»ith the AB-5
and the laboratory standard continuous radon monitor from the large radon
chamber. The radon concentration in the chamber was not changed, and varied
only slightly. The cell counting efficiency \vas determined by setting the
average radon concentration as measured by the AB-5 equal to the average radon
concentration m the chamber as measured by the standard monitor.
Typical count rates at equilibrium were 1.90 counts per hour per Bq/mJ (70
counts/h per pCi/L), with backgi ounds of 60 counts p»?r hour. The piecision of
a single measurement at a radon concentration of 150 Bq/m3 (4 pCi/L) is 20
Bq/m3 (12%). An average of G or muxe readings will have a precision of at least
The relati\e contribution to the counts recorded in each period from the
radon in the sample, and from the activity deposited m the cell b> the ladon in
previous samples, was domed directly by s\sMchmg the monitor input from the
ladun chfinibei to low radon an, and following the change in count rale with
tune. two tui ni pol.\ uuminl collection v> as sufficient lo collect fui activitj
deposited in the cell bj previous samples. 1 he equation used v»as:-
R„ = (C„ - 0.3C„-i)/(0.7K)
vvlicie Rn is the radon concentration in the n'lh sample^ Cn is the net count
ovei the 50 minutes following the sample, Cn-i is the net count foi the f>0
5%.
101
-------
minutes following the preceding n-l'th sample, and K is the number of counts
in 50 minutes for a radon concentration of 1 Bq/m3 (1 pCi/L).
The calibration factors (0.7K) to give radon concentrations in pCi/L as
determined at each calibration for each monitor uere:-
MONITOR
JUNE 1985
JULY 1986
JULY 1987
203
40.5
43.5
43.2
206
42.9
40.5
213
44.3
42.6
228
43.0*
41.8
42.0
238
46.0*
42.0
-12.5
255
43.1
40.1
256
42.3
40.8
257
45.7
43.0
*cell calibrated alone, not complete machine
The sum of the systematic and counting uncertainties in the calibration factoi
amounted to about 1%, or 0.5.
Monitor 206 was not calibrated in Jul} 1987 as it had been returned to the
manufactuier for repair of the charging circuit, and monitor 213 was not v.ith
the project at that time. The calibration factor and background for each
monitor is included in the BASJC program used to convert raw data to ladon
concentrations and is called automatically by the program.
14.3.1. Field Quality Control
Field quality control vvas maintained by t\»o 285 cin1 scmtillat lun cells.
One uas an or dinar j* cell v.hich was Kept closed and therefore contained \ er>
little ration (Dlunk Cell). The other uas a speciallj modified cell containing a
small emanating radium source (Check Cell). These cells were counted in tlie
units on a month]} basis to check that the machines ^eie operating propei l> .
A higher check frequency was used tn the earlj pal L of the program, but found
unneccssnr>.
102
-------
14.3.2. Completeness
The AB-5 has an internal gel-cell battery which will operate the machine
in the quasi-continuous mode for 24 to 48 hours, depending on the initial state
of charge, and will maintain the memory for 1 to 4 days. The machines are
normally run on AC power, and are unaffected by temporary power
interruptions. However, 7 uns were not completed, for the electrical supply
was interrupted for more than 24 hours. The causes included deft' »ivc
receptacles with poor contacts, and switched receptacles wheie the pover was
inadvertently turned off. Th" later models have an indicator to show that the
power is connected, so problems v»ith these machines were due only to power
being turned off after the machine was connected. All the data v.as lost from
one completed run when the on/off switch was accidentally pushed twice. The
first time stops, the machine, the second time starts the machine on a new run,
and erases the data stored in the raemorj. Only time was lost with these
failures, for the i un was repeated to obtain the information.
The AB-5 memory is dumped to a portable computer, which calculates the
radon concentration, produces a hard copy report, and outputs the basic
information for the report on magnetic media. Cassette tape was used as the
initial storage media, and results were Inter transferred to 5»/« inch disks. Of
the 244 completed measurement runs, the data from 1 i uns were lost entirely
due to a recorder malfunction, and some data was lost from a further 1 runs
due to tape faults. In 1986 a 3'/2 inch disc recorder replaced the cassette
recorder, and no data has since been lost in the transfer to storage.
1 1.3.3. Quality As.sul unci.1 Object lves and Performance
'1 he Quality Assurance Objectives for the AB-5 monitors were met. The
a\ci
-------
14.3.4. Problems
The source cell had been modified from a standard cell, and still had the
self-sealing connectors. On two occasions during testing, the cell was
connected to the inlet tubing by mistake, with a short term loss cf radon. The
connectors were blocked to prevent this happening again. There was a slight
leak in the cell, probably at the connectors, and tho count rate of the cell was
affected by changes in atmospheric pressure. Count rates varied from 2 200 to
2 600 cpra. To allow precise comparisons of the machines, a scintillation cell
simulator was constructed with an "'Am source and a scintillation disk mounted
at the end of a tube. The pulse height spectrum from this was similar fo that
from a cell, arid the count rate was unaffected by atmospheric pressure changes.
The count rate of this simulator varied by less than 2% from machine to
machine.
Three machines had defective high \oltage feedback resistors, which ga\ e
increased tube noise as they slowly failed. These machines were identified, and
the resistor replaced with modification hits bent by the manufacturer.
The memory contents of the AB-5 are transfei-red to the portable computer
via a parallel to serial com erter that plugs into the AB-5 printer port. Three
con\erteis were damaged in the winter by static electricity sparks while they
were being connected to the AB-5. One spark damaged the comeiter and also
reset the portable computer memory, and the programs had to b«j reloaded. An
anti-static spray on the nylon office carpet leduced the sparking, but did not
eliminate it. Care had to be taken to ground both the equipment and the
operator when reading out the units.
14.4. SCINTILLATION! CELL MEASUREMENTS
Scintillation cells are used to make giab sample nieasui ements. of the radon
concentration m ducts arid in soil gas. The cells used are plastic bodied cells
with nominal \ chimes of 0.1, 0.5, and 1.5 litres, with nominal sensitivities of 0.3,
2.2, 1.5 cpm pei pCi/L. They are counted ori a 120 mm diuineter pliotnniultiplier
tube, with ft background count rate of less than 1 cpm at the operating voltage.
The cells ha\e a background of less than 2 epin.
Selected cells were calibrated b\ sampling from the EML ladon rhambei,
and those cells were subsequently compared with the other cells b> sampling
101
-------
from a sample of soil gas collected in a 100 litre plastic bag. The sen&itiv Uies
of all the cells did not vary by more than 10% from the nominal value.
14.4.1. Scintillation Cell Field Quality Control
Scintillation cells wuie inspected at each use Tor damage, such as broken
or loose \alves, cracks, or loss of scintillation covering. The photomultiphei and
scaler combination used to count the cells was checked monthly with the 235 ml
radon source cell.
14.4.2. Completeness
The equipment was reliable. Results were obtained for all of the radon
samples taken in the houses.
11.4.3. Quality Assiti ance Ob.iecti\ es And Pel forinanc e
The Quality Assurance Objectives for the scintillation cells weie exceeded.
The concentrations measured were all high enough that the precision o.'
individual measurements was greater than 50%, the calibration factors were not
more than 10% in error, arid all samples taken wcit measuicd.
PRECISION ACCURACY COMPLETENESS
QAPP Goal*. 50% 20% 75%
Actual Pei forinance <50% 10% 100«
14.5. AUDITS
14.5.1. EPA Audits
Field Audits we.'e conducted bj the EPA Quality Assiuance Group in Jul>
1985, Apt il and \o\einbei 1986. They made suggestions regarding measui eineiit
protocols, winch were addressed by modifying the project piotoeols to be in
accordance with the then newly issued EPA Protocol for Indooi M&jsui einents;
external Quality Assurance on the i adon monitor measurements, which weie
nddiessed by pai tic'.pat ion in the EPA Proficiency Progi am; and on iecoru
keeping for the photogi aphs taken of each house. This was addressed by
standai dising photograph size (b\ using onl.\ one pi oi pssui ) so that all photos
105
-------
would fit into a standard photopage, and UBing a camera that automatically
dated the photographs as they v^ere taken.
14.5.2. Internal Audita
An internal audit was carried out in September 1986 to ensure that all
data collected had been transferred to the house files from the field notebooks
and other data sources. Missing data included official copies of DER
measurements in 16 houses, and incomplete house plans for eight houses. The
missing data was obtained over the next two months.
The Project Manager visited all the sites to conduct a final systems audit,
whei e the mitigation sj stem was inspected to ensure that it had been installed
and vwis uoi'lung as intended. A final lntei nal records audits was carried out in
Jul> 1987 to check that the house files contained u complete set of reccrds.
14.G. RADON MEASUREMENT PROFICIENCY PROGRAM
In 1986 the EPA introduced a Radon/Radon Progeny Measurement
Proficiency Evaluation Prograu. to evaluate the performance of Die many firms
that vicre entering the field of radon measurements. Measuring devices uere
e\po.sed 'blind', and the reported concentrations were compared with the knov»n
concentrations by the organizers, and the performance evaluated by them.
Four of the AL5-5 monitors used in this program uere submitted for the
November 1986 comparison round. They gave results within 5% of the measured
average concentration.
106
-------
APPENDIX A
SUMMARY TABLES
107
-------
TABLE A-l PENNSYLVANIA DER MEASUREMENT SUMMARY
KUSNETZ
TEST
BPISU
TEST
TEBBADEI
TEST
VATES
TRST
HOUSE SAHPUhG E3SULT STABT
D DATE !WL) DATS
FINISH ESS'JLT START
DATS (VL} DATS
flhlSB BESULT SARPLIKG EESULT
DATE IpCi/L) DATE IpCWL)
85-02-05 2.207 85-02- 15 85-02-20 0.411 85-02-05 85-03-14 146
85-01-05 85-02-08 <13
85-01-05
85-01-15
85-01-31
85-03-30
85-03-25
85-01-18
85-02-2T
85-02-22
85-01-15
85-01-25
85-02-20
85-02-27
85-01-24
85-02-65
85-03-29
85-01-25
85-04-! I
85-01 -
65-57-03
85 - 08 -C
65-02-22
9.34!
0.360
J.ll02
0.252
0.354
0.461
1.112
!. TO I
C.34C
1.260
0.749
0.220
C .060
0.418
0 ' 7 \
0.630
0.130
0.354
0 32T
1.024
0.153
S5-0M2 85- 04- 25 0 .03 3
55-03-25 55-03-28 0.257
85-01-29 85-02-01 0.J72
8 5 -113 - 0 5 85-03 -08 0 . 5 38
65-02-25 85-02-28 0.128
85-01-23 85-02-01 0.473
85-01-29 85-01-31 I.€33
85-04-C 1 85 -04 -04 0.'.33
85-02-12 85-02-15 0.124
85-04-29 85-05-03 O.tlS
85-01-2? 8 5-02 -01 O.'.ii
85-04-22 85 -H-25 C :<5
£5-02-07 85-02-11 C 614
85-OJ-CJ 85-07-10 f.1^3
S5-0M2 35-03-15 0.46?
$5-02-25 55-02-28 0.465
85-01-31
85-03-30
85-03-25
85-01-18
85-02-27
85-02-22
85-01-15
85-01-25
85-02-20
85-03-27
85-01-24
85-02-05
85-03-29
85-01-25
85-04-11
£5-01-18
85-07-03
85-08-05
85-02-22
85-03-05 350
S5-06-07 25
85-^5-29 29
85-02-22 60
85-03-28 25
85-03-25 183
85-02-15 533
E5-02-25 626
85-C4-29 49
85-06-10 5
i 64
85 03-13 36
i
85-02-25
¦17
sS-iO
85-02
E6-01
85-10
!5 03
t
398
5
21 12
U3 32
30 L«0
27 172
26 700
85-08-23 66 500
65-02-27
»
85-C1 -30
85-02-05
i
85-04-04
<
85-02-12
85-03-19
85-03-25
85-04 -12
85-02-21
85-07-53
85-06-05
85-02-22
LOY
8 0:0
4 30 0
1 4 500
5 4CO
LOW
29 iCO
3 5 200
LCD
4 300
1 2 500
2 50.1
4 900
27 700
4 ECO
1 £30
> 3
66 sOO
1 IOC
108
-------
TABLE A-l (CONTINUED)
BUSWETZ
TEST
EPISU
TEST
HOUSE SAKFL! KG EESl'LT STA ST FISISH
[0 BATE (HI OATS BATE
BEStILT STA2T
(¥L) DATE
TEBBJIDEI VATB8
TEST TEST
PH'ISS SESULT SAHPL1KG mUtT
OATS (fCi/1! jHTE | pCi/LJ
3:
31
3-.
85-01-JQ
85-11-1*
S5-07-23
85-05-10
S5-U5-:i
er-c?-io
65-07-.19
85-??-26
85-08-02
85-10-12
? 5 - J 3 - 2 *
S5-02-I?
f5-1 !-01
16-03-28
SC-04-03
S S - 0 (- 0 T
66-04-0?
if-33-31
85-OM?
85-03-!?
<{-04-22
sS-K-^
0.1?0
0.836
0.176
3 9E5
M3i
!? <12
0.155
0.5S4
0.051
0.16?
O.03&
1.53?
1.926
0.C60
0.313
t.m
0 S34
C .405
a. 255
0.;
'¦ 5 4 5
t >43
85-0S-05 35-OS-eS 0.029 55-07-30 {6-01-JT l\
85-11-14 85- 1 1 - 1 8 0 1 02 B5-11-H 86-02-65 S3
35-07-30 J5-08-C2 0,002 85-07-29
i-01-10
£5-05-14 ef-Ci- 1 7 0. 243 S5-05-i0 8 5 -M-27 121
3 5 - C 5 - i 3 =5-05- 15 0 . 0 1 3 85-05- 06 5£-;i-!2 11
8[-0f-!5 £ £ -CMS 0.038 g£-«7-10 8f-fll-f2 2!
85-iK-jO 15-03-02 0.11-5 S5-07-Z9 $6-9i-!4 2!
85-06-05 S:-OB - 06 0 . 032 85-07-26 £6-01-18 61
85-C8-02 86-01-09 '7
85-03-11 3: - 0 3 -: 4 0.503 $5-02-2; SS-D5-26 £5
:5 - C 4-11 55-0
86-03-28
86-04-03
ii.H.r-
86-04-0?
85-03-31
8 £ - 0 4 -15
-04 0 3
e&-0i-22
250
U
470
Hi
2K
87
0 85-03-2^ - 5 - 0 i -4 30}
111
US
« 8 000
85-11-18 17 900
14 703
i
i
85-05-06
3 7 00
5 100
£5-07-10 1 4 2 01
i 23 COO
65-03-02 235 701
85-03-10 265 908
8£-04-01 22 4Si
S5-M-03
(60
io-04-D: 45 J0C
85-0:-31
ff-M-Si
521
??[¦
2 id:-
55-04-04 14 tOv
« LOt
* 10<
* = Not RepnrfctJ
LOW = "wmcipal Water Suppl.v
109
-------
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
TABLE A-2 HOUSES SELECTED FOR PHASE 1 WORK
LOCATION
APPROXIMATE
PREMITIGATION RADON
CONCENTRATION (pCi/L)
Country
Subdivision 1
Subdivision 2
Town
Country
Subdivision 1
Country
Town
Subdivision 1
Subdivision 1
Town
Country
Subdivision 1
Subdivision 2
Country
Subdivision 1
Country
Subdivision 1
Town
H6
413
350
25
29
60
25
183
533
626
49
6 (0.22 WL)
64
36
- (0.17 WL)
389
9 (0.13 WL)
12 (0.38 WL)
309
110
-------
1
2
3
4
5
6
7
8
9
10
11
12
13
M
1G
16
17
18
38
TABLE A-3 PROPOSED AN'D ACTUAL PHASE 1 TREATMENTS
PROPOSED TREATMENT!' ACTUAL TREATMENT
Sub-slab
Sub-slab
Sub-slab
Sub-slab
Wall
Wall
Sub-slab
Wall
Wall and drain
Sub-slab
Weeping tile
Weeping tile
Weeping tile
Weeping tile
Wall
Weeping tile
Weeping Lile
Wall and drain
Weeping tile
Sub-slab
Sub-slab + wall
Sub-slab + wall
Sub-slab
Wall
Wall
Wall
Wall
Wall and dram
Weeping tile
Wall and dram
Weeping tile
Weeping tile
Weeping tile
Weeping tile
Weeping tile
Wec-p'ng tile
Ventilation
None
111
-------
TABLE A-4 COSTS OF PHASE I MITIGVTIVE WORK
TREATMENT
Weeping Tile Ventilation
HOUSE NUMBER COST $
10 547
12 673
13 755
14 427
15 675
16 701
17 651
Sub-slab Ventilation
1 1 458
2 1 531
3 1 242
4 899
Wall Ventilation
2 408*
3 1 549*
5 1 700
6 1 361
7 1 652
8 1 700
~Cost to add to sub-slab \entilation system
Baseboard Ventilation
9 3 254
11 1 804
House Ventilation
18 150
112
-------
19
20
21
22
23
24
25
26
27
28
29
30
TABLE A-5 NEW HOUSES SELECTED FOR PHASE 2 WORK
LOCATION
APPROXIMATE
PREMITIGATION RADON
CONCENTRATION (pCi/L)
Subdivision 2
Country
Country
Subdivision 3
Country
Subdivision 3
Country
Country
Country
Subdivision 3
Subdivision
Country
32
210
170
24
98
66
121
11 (0.13 WL)
21
21
61
17 (water source)
1)3
-------
TABLE A-6 PROPOSED AND ACTUAL PHASE 2 TREATMENTS
PHASE 1 HOUSES PREVIOUS TREATMENT NEW TREATMENT
1
2
5
6
1
9
11
14
16
17
18
PHASE 2 HOfJSES
2
19
20
21
22
23
24
25
26
27
28
29
30
Sub-slab
Wall plus floor
Wall
Wall
Wall
Wall plus floor
Wall plus drain
Weeping tile
Weepuvg tile
Weeping tile
Ventilation
Wall plus floor (x2)
Wall plus floor
Improved khII
Wall plus floor
Wall plus floor
Improved wall plus floor
None (refused by owner)
Wall
Wall
HRV
11RV
PROPOSED TREATMENT
Water treatment
Wall
Sub-slab
Keeping tile
Slab joint
Slab joint
Sub-slab
Sub-slab
Weeping tile
Keeping tile
Weeping tile
Sump, craul space
Water ti-eatment
ACTUAL TREATMENT
Water treatment
Wall
Sub-slab (\2)
Sub-slab
Slab joint
Slab joint
Sub-slub
Sub-slab
Weeping tile
Weeping tile
Weeping tile HRV
Sump, crawl space
Water treatment
114
-------
TABLE A-7 COSTS OF PHASE 2 MIT1GATIVE WORK
TREATMENT
Weeping Tile Ventilation
HOUSE NUMBER
2G
27
28
29
Sub-slab Ventilation
2
20
21
22
23
24
25
COST S
851
594
271 (sump)
1 598 (sump +)
1 246
970 (s>stem 1)
587 (system 2)
852
860 (joint)
552 (conversion)
1 360 (joint)
1 205
679
Wall VeriCilation
5
7
14
16
19
2 657
2 897
I 851
1 865 (s\stem 1)
t 242 (system 2)
1 80-1
l\all plus Floor Ver.tilut ion
1
2
6
7
9
Improved Ventilation
17
18
Radon Rr>mo\al Ftorn l»at.cr
2
30
1 200 (impro\ ement)
4 171
277 (conversion)
1 3-17 (conversion)
3 241 (impro\emen t)
1 100
500 (modifjcation)
1 100
816
1 796
115
-------
TABLE A-8 HOUSES SELECTED FOR PHASE 3 WORK
HOUSE LOCATION APPROXIMATE
NUMBER PREMITIGATION RADON
CONCENTRATION! (pCi/L)
31 Country 85
32 Country 201
33 Bethlehem 82
34 Country 470
35 Country 144
36 Allentown 297
37 Macungie 87
39 Allentown - (0.345 WL)
40 Easton - (1.15 KL)
1 16
-------
TABLE A-9 PROPOSED AND ACTUAL PHASE 3 TREATMENTS
PHASE 1 HOUSES PREVIOUS TREATMENT NEW TREATMENT
2 None Shielding
4 Sub-slab Sub-slab
6 Wall plus floor Sub-slab
13 Weeping tile Sub-slab/Weeping tile
38 None Sub-slab
PHASE 2 HOUSES PREVIOUS TRFATMEXT NEW TREATMENT
19 Uall None (refused by ouner)
20 Sub-slab Wall'floor plus craul
space
22 Slab joint Sub-slab, flab
23 Slab joint Sub-slab, slab
30 \'one Shielding
PHASE 3 ItOLSES PLAWED TREAP1ENT ACTUAL TREATMENT
31 Sub-slab Sub-slab
32 Sub-slab Sump/Sub-slab
33 Sump Sump/Sub-slab
34 Sub-slt»h Sub-slab
35 Sub-slab Sub-slab
36 Sub-slab plus slab Sub-slab plus slab
37 Sub-slab Sub-slab
39 Sub-slab Sub-slab
10 Sul>-slab Sub-slab
117
-------
TABLE A-10 COSTS OF PHASE 3 MITIGATIVE WORK
TREATMENT
Sub-slab Ventilation
HOUSE NUMBEH
4
6
13
22
23
31
32
33
34
35
36
37
38
39
40
Kail Ventilation
20
House Ventilation
28
Radon Removal from Water
2
30
COST S
2 026
758 (cornersion)
1 129
1 3S8 (extension)
1 825
881 (extension)
] 700
1 686
897 (sump)
2 878
1 183
2 478
1 556
1 760
1 100
4 255
514 (extension)
257 (addition)
1 240
487 (shielding)
981 (shieldirig)
118
-------
TABLE A-ll COST OF SMALL SYSTEM MODIFICATIONS AN'D FAN CHANGES
HOUSE NTJMBE3? COST $
PHASE 2
1
3
6
8
9
10
13
15
PHASE 3
3
5
7
8
12
21
24
25
26
27
29
551 (fan change)
275(fan change)
295 (raodifications)
269 (fan change)
491 (fan change)
351 (fan change)
222 (fan change)
313 (fan change)
438 (fan change)
267 (fan change)
379 (fan change)
331 {fan change)
192 (fan change)
589 (fan change)
613 (fan c-hange)
579 (fan change)
412 (fai change)
362 (fan change)
432 (fan change)
119
-------
TABLE \-12 SUMMARY OF POST MITIGATION ALPHA TRACK RESULTS
HOUSE
DATE OF
DATE OF
ID 4
INSTALLATION
REMOVAL
1
House Moved
2
86-12-17
87-03-16
3^
85-12-05
86-03-20
3A
86-12-14
87-03-19
4
87-01-16
87-03-19
5
87-01-16
87-03-19
6
87-01-16
87-03-19
1
87-01-16
87-03- 17
8
85-12-06
86-03-20
8
86-12-18
87-03-25
9
86-12-17
87-03-16
10
85-12-05
S6-03-11
10
86-12-17
87-03-16
12
86-12-15
87-03-19
13
85-12-13
86-03-31
13A
87-02-21
87-04-11
14
86-02-18
gr-04-26
14
86-12-18
87-03-17
15
85-12-08
86-03-12
15
86-12-17
87-03-18
16
86-01-04
86-01-21
16A
86 -03-14
86-05-20
ISA
86-12-16
87-03-16
17
87-02-21
87-04-11
18
87-02-21
87-04-11
19
86-12-18
87-03-16
20
87-03-10
87-03-29
21
86-12-14
87-03-16
22
87-02-21
87-04-15
23
87-01-26
87-03-19
24
87-03-06
87-04-15
25
87-03-10
87-04-15
26
86-12-1C.
87-03-16
27
86-12-16
87-03-16
28
87-02-21
87-04-21
29
87-02-21
87-01-15
30
86-12-17
87-03-19
31
87-0 t-10
87-03-19
32
87-01-21
87-03-19
33
87-03-07
87-04-1 3
34
87-02-19
87-01-15
87-02-21
87-04-14
36
87-03-06
87-04-15
37
87-02-19
87-01-17
38
87-03-10
87-04-11
39
87-06-20
Not yet
40
87-06-19
"
BASEMENT LIVING SPACE
AVERAGE(pCl/L) AVERAGE(pCi/L)
2.6
5.2
4.4
1.7
3.5
2.1
0.7
0.8
4.3
4.3
3.3
4.9
4.1
2-8
3.1
1.3
3.9
1.8
11.6
14.5
3.3
3.0
9.0
6.5
3.7
2.5
17.0
11.4
2.3
2.0
0.7
0.6
0.5
0.7
3.8
2.5
1.1
1.0
78
22
2.9
2.4
5.4
1.7
7.6
4.1
8.8
2.1
32.0
0.6
5.8
9.9
3.1
2.6
7.6
2.7
7.6
11.6
4.
4.6
5. 1
3.0
2.1
1.5
3.8
2.2
2.4
5.3
1.9
1.4
3.0
1.3
1.8
5.7
1.0
3.2
2.2
1.1
5.5
3.7
0.7
0.8
1 .6
1.7
0.6
0.6
14.4
11.2
remo\od
120
-------
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1G
17
18
19
20
21
TABLE A-13 SUMMARY OF GAMMA SURVEY RESULTS
INTERVAL FIELD
(uR/h)
RANGE AVERAGE
EXTERNAL FIELD
(uR/h)
RANGE AVERAGE
ADDITIONAL COMMENTS
8-11
10
11-12
11
exposed subsurface cut 17-20 uR/h
11-15
13
8-12
10
surface cover from basement
excavation 20 to 35 uR/h
5-11
5
5-12
9
7-12
10
12-15
14
6 uTJ/h at asphalt driveway 18 uR/h
at exposed road bank
4-7
5
6-\0
8
6-12
10
6-12
10
7-10
8
8-13
11
6 uR/h on asphalt driveway
6-12
9
6-10
9
7-10
9
10-1-3
12
pool excavation dirt 14 uR/h; in
excavation range 14-42 uR/h
9-14
10
10-35
20
6-9
8
7-10
9
exposed soil at road cut
13-16 uR/h
3-fi
5
5-9
7
5-12
9
8-25
16
driveway 4-10 uR/h
6-10
8
5-12
10
4-10
S
8-12
10
1-10
i-»
i
5-19
13
7-9
8
9-12
11
interior high spots of 10-12 uH/h
by sump and in cedar closet
1-6
5
6-7
6
5-9
7
5-8
6
5-15
9
11-27
16
hot wat" or tank 39 uR/h on eon tact
4-7
5
7-12
9
-------
22
23
24
25
26
27
28
29
30
31
32
33
31
35
36
37
38
39
40
INTERNAL FIELD
(uR/h)
RANGE AVERAGE
TABLE A-13 (CONTINUED)
EXTERNAL FIELD
(uR/h)
RANGE AVERAGE
ADDITIONAL COMMENTS
3-6
5
5-10
8
4-16
7
6-16
12
2-6
4
6-10
9
10-16
13
8-14
11
4-8
6
5-10
j•»
t
4-9
6
12-25
16
4 -8
6
4-10
7
5-7
6
8-14
12
-12
8
7-13
10
-13
8
5-14
11
18
5
2-12
5
-8
n
1
7-9
7
-1
7
5-10
7
-5
5
3-4
4
-9
7
3-10
7
-9
6
5-8
7
¦-12
10
8-12
10
-11
9
9-18
13
-10
8
9-11
10
13 uR/h on contact with well
pressure tank; 6 uR/h at driveuay
2 radium dial compasses in closet
gave up to 150 uR/h
8-9 uR/h an crawl space
12-14 uR/h neai sump, 10-13 uR/h
near well pressure tank
12 uR/h in vicinity of well
pressure tank
hot spots of 12 and 18 uR/h
3 m dj
-------
APPENDIX B
PUBLICATIONS
123
-------
Publications arising from the work carried out in this project.
1. Henschel, D. B. and Scott, A. G., "The EPA Program to Demonstrate
Mitigation Measures for Indoor Radon: Initial Results", Indoor Radon:
Proceedings of an APCA International Specialty Conference, pp. 110 - 121,
Philadelphia, PA, February 1986.
2. Henschel, D. B. and Scott, A. G., "Testing of Indoor Radon Reduction
Techniques in Eastern Pennsylvania: An Update", in Indoor Radon II:
Proceedings of the Second ^PCA International Specialty Conference on
Indoor Radon, pp. 146 - 159, Cherry Hill, NJ, j®pril 1987.
3. Henschel, D. B. and Scott, A. G., "Some Results from the Demonstration
of Indoor Radon Reduction Measures in Block Basement Houses", in Indoor
Air '87: Proceedings of the 4th International Conference on Indoor Air
Quality and Climate, Vol 2, pp. 340 - 346, Berlin, West Germany, August
1987.
124
-------
APPENDIX C
INDIVIDUAL HOUSE DESCRIPTIONS
1 2r>
-------
HOUSE 1
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Heating season average (RPISU)
Heating season radon average (Terradex)
Radon in water
27 000 pCi/L
2.207 WL
0.411 WL
146 pCi/L
1. DESCRIPTION
This single stor\ house was built by the owner in the late 1950's on a
fairly lex el site near the top of a ridge se\eral miles west of Boyertown. One
half of the front house vail is brick veneer, the other walls tire siding. Heating
is by oil fired hot wpter baseboard convectors upstairs, supplemented b.\ a wood
stove in the basement.
The basement wills, and two central support walls are of hollow cmcler
block. Two internal buttress walls are of concrete block. The internal walls
penetrate the floor. There is an external entrance into the basement.
The concrete floor slab was poured in sections and there are several
construction joints. The well pressure tank is supported on concrete blocks
whose \oids pencil ate the floor. There is a trapped basement floor drain. The
basement is approximately one third finished, with wood panelled vails, a oar,
and a suspended ceiling.
2. ACTION
2.1. PHASE 1
As the basement wus partially finished, the mitigation measure selected for
demonsti ation at this house was subslab ventilation. Tuu exhaust points veto
necessarj due to the length of the house, and the subdi\ision of the subfloor
space b> the footing beneath the buttress walls.
A Hilt i electric percussion chill was used to drill 12 holes around the
perimeter of a 60 cm circle, arid an air hammer was used to break out the
concrete. When the holes wore cleaned out it was found that lnb at the
workshop end was jjoured diiectl> on solid bedrock. The air hammer was used
126
-------
to break up the rock to a depth of 10 to 15 cm. At the laundry end of the
basement., there was about 8 era of broken bedrock over solid bedrock.
The holes were cleaned out, and 10 to 15 cm of "1/2 inch" clear crushed
stone was placed in the holes and a "4 inch" lightweight plastic drain pipe 'as
placed vertically into the stone. As an experiment, ealvunized i..etal sheet was
used to cover the stone in the workshop hole, and styrofoam was used in the
laundry hole. The edges of the cover material were caulked to the slab and the
pipe with asphaltic cement, and the hole filled to floor level with 5 cm of
concrete made from a ba^} nnx.
The basement layout and degree of ir.ctrnal finisn made it impracticable to
join the risers together with concealed piping, and the lack of subslab material
suggested that one fan might not be sufficient. The pipes were extended
vertically to the joists, and then run to the closest basement window. In the
laundry a small centrifugal fan was mounted directly on the outside face of a
plywood sheet placed in the window opening. The fan was small enough to fit
into the window well \\ith a weather cover over it. The other fan was a large
r^ntrifugal exhaust unit fitted on a wooden box, with a flexible connection
through a plywood sheet replacing a window in the work room.
In June 1985 the radon concentration in the casement prior to any work
varied from 140 to 220 pCi/L, averaging 18C pCi/L. In July 1985, with the fans
turned on the concentration ranged from 141 pCi/L to 188 pCi/L, averaging 1GG
pCi/L.
A smoke tracer survey of the floor was carried out, and the smoke was
observed to be drawn down through the few \isible cracks arid openings in the
floor near the exhaust pipes. The fans drew very little air. The laundry room
fan drevx only 5 L/s at 105 Pa suction, and the workroom end fan drew only 3
L/s at SO Pa.
2.2. PHASE 2
As the subfloor s>stem was so ineffective, the options for additional
mitigative work were limited. The subfloor performance could oril.v be .ir.pr<>\Hd
by removing the entire basement floor, placing a laver of ciushed stone o\ei
the bedrock, and pouring a new floor. This would be disruptive, expensive,
reduce the h.'isvement headroom to 2.0 m, and still could not prevent soil £.tt> :md
radon entering through t lie walls. As excellent performance had been obtained
127
-------
at other sites by ventilating the walls, wall ventilation seemed the most
cost-effective solution at this site.
This house was considerably larger than the other houses where wall
ventilation had been used, and the installation would also have to include the
interior walls. Rather than just insei ting a ventilation pipe at one or two
places per v-.aU, it was decided to treat both the walls and the floor by using a
perimeter duct that would cover the wall floor joint.
The basement walls v.ere made of cinder block, und were very porous. The
owner said that he had not parged the e\tenor walls below grade. The
ductwork was therefore designed to have double the cross sectional area of the
previous installations. The initial design was for only one fan, (a large wall
mounted centrifugal) but there was provision for a similar fan to be installed at
the oppoFi* end of the basement if needed.
In \'o\ ember 1935, the owruu removed the basement panelling, and
disconnected the electrical wiring. The subfloor s> stem was removed and the
holes, filled with mortar. The well pressure tank was removed, and the openings
through the floor were filled with moi and sealed with usphaltic sealant.
The block \oids wete exposed on the internal stub walls, beneath the
windows, and on end walls. These were filled with mortar. The block voids on
the front and rear walls, where the access was too poor to use mortar, were
closed by nailing wood strips to the sill plate, and caulking the gap between
the x-.ood and wall top. Holes weie drilled into each void of the lowest block
course of the walls, and an 8\30 cm rectangular baseboard duct was installed.
This ran round the basement in a 'C' loop, with a gap of about 3 111 total at
the exterior door.
As work progressed, many sm.\ll openings in the walls and mot tar were
noticed, jnu it became clear the walls would not be made airtight by local
patching alone. One option considered was to cover the walls with polyethylene
sheets, but the final choice was to paint the walls with a cement based
waterproofing paint. This formed a continuous airtight film ovei the surface of
the blocks, and bridged riacks and openings if applied thicklj. The paint \ehii.le
was 30% iiiv I toluene, 70% aliphatic, hv drocai bons, and had a strong unpleasant
odour. The residents- were sent to a motel foi two d
-------
The system was essentially complete in December 1985. Over the period 13
December to 6 January the radon concentration in the basement with the fan
running varied from 12 to 159 pCi/L, averaging 80 pCi/L.
Investigation in Januarj 1986, found that one fan was not sufficient, for
only the front wall of the house was lower in pressure than the basement. Air
flowed out of the rear and end walls into the house. Radon concentrations in
the ducting were 60 pCi/L at the rear wall, 160 and 270 pCi/L at two points on
the front wall, and 210 pCi/L at the end wall. The basement radon
concentration was 45 pCi/L at that time
Additional ducting wa-- added over the rear basement door to mako a
continuous loop of ducting round (.he basement, and the second fan was added.
All the -.alls were then under suction.
A relatively high airflow came from the smalt section of the front basement
wall that v.?»s topped with brick veneer. To increase the airtightness, 10 cm
diameter holes were drilled through the header board, exposing the junction
between the brick facing and the block wall. The gap was generally filled with
mortar droppings, but expanding ureth«ne foam was injected into the space to
increase the airtightness. The airflow out of this portion of the sail decreased
oul> slightly, suggesting that, there were subsurface routes of entry as well.
In late January 1986, the radon concentration in the basement with both
fans on varied from 4 to 25 pCx/L, averaging 10 pCi/L.
The owner complained that his basement wood stove was now difficult to
light, and would smoke on a low fire. Despite the extensiv e efforts to close
the leakage areas from the house into the walls, the two fans were still
drawing large amounts of air from the house, and hence back drafting the stove.
It was decided to re\ erse the fans so that they would pressunze the walls, and
prevent backdraft ing.
Before the fans wete revel sed, an extensive investigation was curried out in
Kebruurv 1986, to see if the entry route of the remaining radon could be
identified. Temporary enclosures were placed over joints in the basement
structure at 20 locations, nnd Lhe radon concentration in the enclosure
measured IS hours lalrr. High indon contenti ations indicating soil gus entrj
wore found only at 2 locations, 900 pCi/L over a sewer cleanout sot into the
fl<»or, and 550 pCi/L at the wall/floor joint on a buttress wall despite the wL-Il
being under negative pressute. An additional 9 wail/floor joint locations wete
129
-------
tested in the same wa>, Fi\e of the enclosures had concentrations in excess of
200 pCi/L, indicating that suction in the walls was not transmitted effectively to
the subfloor space.
In March 1986, the fans were replaced by temporary small centrifugal
blowers. The radon concentration in the basement initially rose from 6 to 70
pCi/L in four hours, then fell slowly over the next 24 hours, finally ranging
from 13 to 18 pCi/L, and averaging 15 pCi/L.
Even though the connection was poor between the walls and the subslab
space, pressurizing the vails would still lend to force soil gas up from henealh
the floor. Accordingly, the ducting was extended to civer the wall/floor joint
both sides of each internal support and buttress wall to prevent soil gas entry in
these areas. The radon concentration in the basement following tins varied froin
16 to 37 pCi/L, avernging 25 pCi/L. This decrease in performance suggested that
the increased pressure at the perimeter of the floor slab was now forcing soil
gas out of hitherto less ir portant openings in the centre of the floor.
Investigation in March found that the radon concentration in t>'f vails v>as
5 to 9 pCi/l. \> hen the basement concentration was 9 pCi/L. A smoke stick
survey found small airflows from the subfloor space into the house via holloa
oil tank legs, floor joints, and uhere the stair stringers passed through the
concrete floor. The radon concentration in the tanl< leg with the highest flos
was 1 100 pCi/L.
\fter thes» openings were closed, the radon concentration in the basement
ranged from 13 to 17 pCi/l., averaging 15 pCi/L. When the fans were turned
off, the radon concentration started to rise after a delay of 12 hours, and
reached a maximum of 98 pOi/1, after 36 hours.
This has interpreted as shoeing that pressurization was effective in
displacing radon rich soil gas awaj from the house, and that larger
pressurizatton fans might give better performance.
In May the temporal y blowei s were replaced by large \>all mounted
centrifugal blowers which produced a pressure of 11 Pa in the ducts. Uitli
these fans in operation, the radon level m the basement langed from 1 to 3
pCi/l,, except for a peak to 14 pC/1 when the cashing machine uas used. Uher.
the fans < "re tu'-'ied off, it again took nenrlj 12 hours before concentrations
started to increase, and the maximum concentration of 17 pCi/L uus not reached
until the follow : rig Any.
130
-------
2.3. PHASE 3
In November 1986 the radon concentration in the basement with the fans in
operation ranged from 3 to 16 pCi/L, averaging 5 pCi/L. The high
concentrations were associated with use of the cashing machine, and were
attributed to release of water-borne radon.
Further measurements were not made in this house as the owner sold the
site. The house was moved in December 1986 to a new foundation several miles
away.
3. OTHER MEASUREMENTS
Radiation fields on the site ranged from 11 to 12 uR/h near the house but
where subsurface soil was e.\posed on a cut on the uphill side of the site, the
field was 17 to 20 uK/h. The field in the basement ranged from 8 to 11 uR/h,
axeraging 10 uli/h.
131
-------
MEASUREMENTS SUltflARY FOR HOUSE 1
PYLON AB-5 HOURLY MONITORING
PHASE
MITIGATION
SYSTEM
TEST
DATE
STATUS DURING RADON (pCi/1)
TEST RANGE MEAN
Central sub-slab 06/87
ventilation
50 L/s and
100 L/s
centrifugal fans
07/85
Premitigation 140-220
As above
Baseboard
ventjlation of
wall 100 L/s
centrifugal
As above
TVjo 100 L/s
centrifugal fans
08/85
12/85
01 /86
01/86
03/86
Fans off
Fans on
Fan on
Fan on
Fan on
Fans on
Fans on
Fans on
Fans on
Baseboard
ventilation of
walls tuo 50 L/s
centrifugal fans
on blow extended
to all interior
walls
Basfbnard
\entiJation of
walls tuo 50 L/s
rentrlfugal on
blow openings at
ojI tank leg and
staii stringers
closed
03/86 Fans on
04/86
Fans on
Fans off
126-143
141-188
17-116
12-159
50-118
4- 25
6-70
15-70
13-18
15- 37
13 -17
14- 98
180
135
166
79
80
84
10
42
33
15
22
15
44
COMMENTS
over 53 hrs
over 15 hrs
over 21 hrs
o\er 24 hrs
over 22 dajs
o\er 53 hrs
over 4 days
Initial 4 hr
rise
33 hr fall to
equilibrium
36 hrs at
equilibrium
over 4 days
over 38 hi-s
o\er 14 hrs
still
cllmbing
132
-------
MEASUREMENTS SUW1ARY FOR HOUSE 1
PYLON AB-5 HOURLY MONITORING
PHASE MITIGATION TEST
SYSTEM DATE
2 Baseboard 05/86
ventilation of
walls two
150 L/s
centrifugal fans
on blow
STATUS DURING RADON (pCi/L)
TEST RANGE MEAN
Fans on
Fans off
11-14
2-47
3
26
OO^IENTS
o\er 4S hrs
over 51 hr
slow rise to
equi]ibnum
of 32 pCi/L
Baseboard
\entilation of
walls two 150
L/s centrifugal
fans on blow
11/86 -oris on
3-16
over 90 hrs
SYSTEM MEASUREMENTS FOR HOUSE 1
PHASE
MITIGATION SYSTEM DATE
Central sub-slab
\entilafion 50 L/s
and 100 L/s
centrifugal fans
SYSTEM MEASUREMENTS
PRESSURE FLOW RADON
Pa (L/s) (pCi/L)
11/85 106
90
Baseboard ventilation 01/86
100 L/s centrifugal
fan
0. 1
270
160
210
60
45
800
COMMENTS
l^aundij rm f;ui
Workroom fan
Front, w duct
Front w duct
End w r j ser
Rear w riser
i-oom air
Floor drain
02/86
A
0
9
1
280
Indoor air
Outdoor air
Indooi air
Bsmnt. door
Hoc. Rm Fan
disch.ii'fje
133
-------
SYSTEM MEASUREMENTS HOISE 1
phase mitigation systim date
liasf-hoai-cl \ei'.t llation 03/86
t uo 50 L/s
centi ifilial fains on
bW-
baseboards t_*\tended
to all intet lor blocK
w ills
SYSTEM MEASUREMENTS
PRcSSI.TJE FLOW RADON'
Pr. (L/s) (pCi/T.)
COMMCNTS
30 oil laiJt Ic'ri
30 oi 1 tcuik le/t
20 oil tank 1<>£?
1 100 oil tank lee
5 front i.all
0 rear l.all
9 basement air
Hi
-------
BASEBOARD DJKTT MEASUREMENTS
DUCT POSITION
1
10
11 12 13 14
FLOW IN DUCT AT POSITION (L/s)
System - Baseboard ventilation 100 L/s fan 01/86
4 4 8 8 9 10 11 17 18 28 59 7 7 -
System - Baseboard ventilation with two 100 L/s fans 01/86
2 31 9 15 22 - 2 11 21 78 11 8 76
System - Baseboard ventilation with two 150 L/s fans 05/86
28 - 11 15 8 1 2 11 11 43 8 2 55
PRESSURE IN DUCT AT POSITION (Pa)
S>stem - Baseboard ventilation with tvo 100 L/s £ans (Suction) 01/86
3 18 - 20 13 13 - 15 15 15 25 15 4
S>sten - liaseboard ventilation with two 150 L/s fans (Pressure) 05/86
11 - 11 11 11 11 11 11 11 13 11 5 1
RADON MEASUREMENTS AT POSITION' (pCi/1)
System - Baseboard ventilation with two 150 L/s fans 05/86
0 - 0 0.4 0.4 0.6 0.5 0 1.7 1.4 0
0.
135
-------
ROUTE OF RADON ENTRY SURVEY
RADON CONCENTRATION (pCi/L) IN FLOOR ENCLOSURES
ABCDEFGHI JKLMN
System - Baseboard ventilation of wall with two 100 L/s fans 02/86
870 7 10 3 540 20 9 33 2 8 11 3 3 5
RADON CONCENTRATION (pCi/L) IN WALL/SLAB JUNCTION ENCLOSURES
#1 #2 #3 #4 #5 #6 #7 *8
19 520 290 65 13 220 490 750
LIST OF MEASUREMENT lOCATIONS
POSITION
FIjOOR
ENCLOSURES
WALL/SLAIi ENCLOSURES
1-
rear wall duct near
cleanout
#1
stair wall
laundry
U:
cold joint
#2
wing wall
2
rear wall duct
C:
cold joint
#3
wing wall
central
D:
cold jomt
stair wall
3
driveway wall at
F:
wall/slab
+5
stair xjser
real
F:
cold joint
#G
stair wall
4
driveway wall before
G:
crack
tr 1
wing wall
pj laster
H:
concreted area
central wall
5
driveway wall after
I:
coLd joint
pilaster
J:
drain
6
dnvewaj wall at
h:
bloclc in slab
front
L:
cold joint
r*
t
front wall before
M:
pipe
wing wall
penetration
8
front wall afLer
N:
furnace slab
wing wall
9 fiorit wall at jog
10 fiorit wall at end
11 end wall at fan
12 end wall at centre
13 mill wall ul luiindty
ar «*h
14 ijsi-t to fan 2
136
-------
25-6
CINDER a>l_OCK-
FOUMDATiOM
WA.LL VYR
/UHLE-&S
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NOTEt>)
£s|— WATE6
TANK
|4-o
25D6F'vJ
POMEO ?AM
c-himwet
E72±Z
UTILITY ,
' /f
REG.
ROOM
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3. IMTEKIOR V/ALLi PEUETRATE *5A_^e>
LOW COST REDUCTION OF BSSDOOR RAD0E3
HOUSE
NUMBER
IIS
FOUNDATION PLAN
0 q t e: t\/zo/&£,
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Mitigation aystsm: a*0^ ppc^iic,A"r"*,4
PHASE:
1
137
-------
HOUSE 2
PENNSYLVANIA DER MEASUREMENTS
Working Level samples in basement (Kusnetz)
Heating season basement radon average (Te^radex)
Radon concentration in water
0.350 WL
413pCt/L
67 000 pCi/L
1. DESCRIPTION
This single story dwelling with adjacent two car garage was built in the
mid 1970's on a sloping site at the top of a ridge m a rural subdivision to the
uest of Boyertown. The front house wall is .brick veneer, the other walls are
siding. Heating is by hot water circulating through radiators from an oil-fired
boiler. The purtiallv finished walk-out basement has concrete block walls.
The poured concrete slab has a small wall/floor joint. There is an open
construction joint across the centre of the slab, a large diagonal crack at the
garage end, and the well pressure tank is supported oil concrete blocks laid with
the voids penetrating the slab.
There Hre no serious cracks visble in the concrete block walls, which are
all painted. The top course of the exterior walls zs completely covered by a
sillplate caulked into place. There is a central concrete block structure that
encloses a brick faced basement fire place and the boiler flue. These blocks are
open at the top.
2. ACTIONS
2.1. PHASE 1
The mitigative action selected for initial demonsti ation at this house was
sub-slob ventilation. If this uere unsuccessful, then uall ventilation uas the
ne\t choice, for it could be carried out easily since tho tops of the walls \%oie
closed with the caulked sillplate.
Sine the basement whs much longer than \»ide, tv*o e\haust points wen;
needed on the centra line, em h one quarter of the way from eithei end. The
final locations wet e adjusted slightly to place the pipes as much out of tlu, i»ny
as possible.
In June 1^83, two 50 cm -diameter holes were opened m the concrete slab
by means of an air hammer arid compiessor following gi:id<- holes inadc by a llilti
138
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drill. The sub-slab material was crusher run stone winch was removed and
replaced by 1/2 inch clear crushed stone. This was covered with a sneet of
roofing felt cut to fit the hole arid caulked to the concrete with an asphalt
caulk. A vertical exhaust pipe of 1 inch schedule 40 PVC sewer pipe was
placed in the crushed stone through a hole in the felt cover, and caulked. The
holes were then concreted over.
The two vertical pipes were connected into a horizontal run of 4 inch
schedule 40 pipe which led to a front basement window, which v«as temporarily
replaced by a sheet of plywood, A flexible hose ran from the pipe, through the
plywood sheet to a large centrifugal exhaust fan installed on a pij wood sheet
placed on top of the window well.
In July 1985, with the fan turned off, radon concentrations in the basement
varied between 80 to 503 pCi/L, averaging 243 pCi/L. Uhen the fan was tuined
on, concentrations varied between 30 to 53 pCi/L, a\erpgirig -11 pCi/L. I his
was on encouraging reduction, but the high residual concentrations indicated
that the system was not treating all the routes of radon entry.
Previous measurements by another contractor had indicated that the garage
end v.ull of the basement was u major radon soujce, so a further reduction »n
radon concentration was sought b> extending the ventilation into that wall. Jn
August 1985, a T-connector was added to the top of the sub-slab ventilation
pipe nearest to the garage wall, and a 4 inch schedule -50 plastic pipe was iun
from there ir:*o the garage end wall.
At the same time, to reduce the area of floor leakage paths, the major
construction joint and the floor cracks were cleaned and filled with % myl
concrete filler to reduce the floor leakage area. Openings around watei lines
through the floor uerc caulked with asphaltic sealer.
\'o attempt was made to treat the other walls oi the largo concrete block
cential structure. These were left for Phase 21 of the program.
In August 1985, with the fan running continually radon concentrations in
the basement ranged from 12 to 56 pCi/L, averaging ?8 pCi/l..
%
Examination found that, air flowed from the house into the eninc gaia^e
wall, and also into all the othei external walls. -\ir flowed down tluough .til
crntkh and openings hi the garage erid of tile basement flooi , in< ludiug the
openings beneath the well piessuie tank. The floor was inaccessible .it the
other end of the bastmc-nt where there was a stmagi" room ai.d a ^otK room
139
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with a built up wood floor. The fan produced a suction of 60 Pa in each pipe at
floor level.
The minor reduction in radon concentration produced by ventilating one
wall indicated that there \%ere still other routes of entry. The internal block
wall structure was regarded as the probable route, for it penetrated the slab,
was not keyed into the exterior walls, and was open Ht the top. Further work
was delayed until the fall, to enable evaluation of tho s) stein under cold weather
conditions.
2.2. PHASE 2
In October 1985 a spot WL measurement found levels equivalent tc
3 000 pCi/L in the basement. The owners were concerned over these high
levels, and started to install an air-to-air heat exchanger (heat recovery
ventilator or HRV). This entailed disconnecting part of the sub-slab system
piping to allow installation of the air distribution duct uorlt, so n test of the
full system uas not possible until late December, when it was reconnected.
Investigation in December 1985 found thai air was still drawn dov»n 4 100 pCi/L m the exhaust air,
despite withdrawing 4 L/s of atr from the sub-slab space for 3 months.
From December 13, 1985 to December 19, with the HRV in operation and
the sub-slab system operating with just one extraction point, radon
concentrations in the basement ranged from 90 v»Ci/L to 522 pCi/L, averaging
250 pCi/L. The sub-slab system was reassembled on December lfi, mid both it
and the HRV continued in operation until Ueoeitibor 28. Radon concentrations in
the basement ranged from 2G pCi/L to G92 pCt/L, a\erasing 400 p(}i/L.
The HN\ wah turned off from December 2S to January 5, J98G. Radoii
concentrations in the basement with jusl the subfloor sj-stein operating ranged
from 13 pCi/L to 1 47G pCi/1 , averaging 1 tKX? pCi/l.. The HRV \%as turned on
again on Janjary 5, I98fi, and measurements were made (ill January 7. Radon
concentrations ranged from 203 pCi/L to ti82 pOi/L, averaging -139 pCi/L.
The rudon concentrations i*ith just the sub-slab s\ stem on \.oi'o comparable
to those measured the previous u inter, and it vns clear that the existing
s\ stem was not reducing the ladon supply sisjnificantlj, The factor of two
i eduction ptoduced by HRV operation wis encouraginn, but fat ftom the
reduction factors of 20+ needed to approach tolerable radon levels.
1 10
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The only improvement to the sub-slab system that could be made rapidly
was to ventilate the central block fireplace structure, which was suspected of
being a soil gas entry route as it penetrated the stab. This could be done and
the result tested while an improved mitigative system was being designed.
The top course of blocks was removed from the structure without disturbing
the brick facing on the fireplace side. This save a working space 25 cm high.
The voids of the second course of blocks uere stuffed with fiberglass as a
temporary support and filled with mortar. This greatly reduced leakage area,
but did not close the structure entirely, for the space between the chimney flue
and the surrounding blocks could not be filled without major structuial work.
A 2 inch plastic dra:n pipe was inserted into the void of a second cuui sl*
block, and Teed into the exhaust line of the sub-slab system. 1 he first couise
of blocks was replaced and repainted to match.
The effect of this change was. minor. In January, with the system fan
running continually and the HKV in operation, radon concentrations in the
basement ranged from 287 pCi/L, to 498 pCi/L, averaging 397 pCt/L. With the
HRV turned off, the concentrations ranged from 87 pCi/L lo 950 pPi/1 .
averaging 300 pCi/L. No measurements were made with the fan turned off, for
the occupants were concerned that even higher radon concentrations might
result.
Radon concentrations in the indi\ ldual exhaust pipes were 10 700 pCi/L in
the laundry room pipe, 2 350 pCi/L in the other floor- e.xhaust pipe, -1 300 pC'/L
in the garage wall, and 165 pCi/L from the central block wall - approximately
the room air concentration.
The conclusion was that there wore much, more important routes of radon
entry than the central block structure.
2.3. PHASE 2\
By this time, results from other e.xpei imental houses hat! indicated that wall
ventilation alone was not always an effective solution. Accordingly, it was
decided to install a combined viall and wall/floor joint ventilution system lo tiuat
all five sm fju.es of the basement.
The system consisted of an JJ inch wide flat sheet metal cover, locally
fabricated in 10 fool lengths, placed o\ or the wail/floor joint at u GO degiee
angle. The ssstem dimensions were chosen so that a "2 by -1" could be installer
as a sp/.ocr ab^vo Uie cu\ cr it the walls wore Framed and finished. Holes t% cm e
1-11
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drilled into every cavity of the lowest course of blocks so that air could be
drawn oul of the wall into the duct formed by the cover. The duct would also
collect any soil gas that entered through the wall/floor joint.
The basement was divided into two halves by the internal concrete block
wall at the front of the house, and the rear wali was divided into three
sections by a single door and a double door. To deal with this two separate
sets of ducting were pro\ided, each with its own wall mounted large centrifugal
fan. One set treated one half of the front wall, the garage wall, and the rear
wall as far as the single door. The other set treated the other half of the front
wall, the central block structure, the end wull, and the remaining pari of the
rear wall. A closed duct ran yound the double door to carry the suction to the
portion of the rear wall between the two doors.
A workroom at the front of the basement hud a built-up wood floor and
frame vails covered with wallboard. The upper plule <>f the veil] was spiked to
the joists, so it wan possible to cut off the bottom 20 cm (8") of the studs and
take out the sole plate without removing the floor. This exposed the wall/floor
joint. When this was done, and piled lumber und other stored material was
removed from the adjacent storage end of the basement, a significant wall/floor
joint was exposed all along the end wall. Smoke tests shoved that there was a
visible air inflow there, even with the sub-slab system in operation. The suction
did not extend to that end of the basement, even though it was close to up.
exhaust pipe.
TI«t duct installation was completed on January 1986. Each fan drew
about 50 L/s {100 cfm), and air flowed into all walls. Radon concentrations in
the air drawn from the walls ranged from 300 pCi/L at the roar wall, which
was completely out of the ground, to 4 000 pCi/1. from the fiont garage wall
corner.
The radon conn-nti at ion in the basement with the IIRV running and the
sub-slab s>steni turned off, fell from 200 p'\/L to 15 pt'i/L within a day. With
the sub-stab s> stem till ned on as well, i.oneentrnUons landed from 7 to 25 pOi/L,
averaging 15 pCi/L. 'I his indicated that tlx- sub-slab svsteni did not provide
ir'j;_h addi'ioea! effect.
The system was inspected to find if thei e was an obvious cause fo: tin.
concentrations to slill be in the region of 15 pCi/I.. Smoke tests showed th'it
ir<:
-------
air flowed into all walls and the central block structure, and into the floor,
suggesting that the route of entry was concealed.
The smoke tests also found a number of joints in the ductwork that had
not been effectiv elj caulked. Closing these increased the wall suction, and
decreased the amount of air drawn from the house. This was important, because
with the HRV extruding air from the basement, and all the radon control fans
running, air was draun down the basement chimney.
Following this, '-np^enlrations in early February with the HRV and the sub-
slab system on, ranged from 2 pCi/L to 10 pCi/L, averaging 5 pCi/L.
The concenti ation peaks seemed to be associated with water usage, so a set
of measurements were made in early March 1986 in a bathroom and in the
basement close to the washing machine. Bathroom concentrations rose from
2 pCi/L 1c. 220 pCi/1. when the shower was run, and short term peak
concentrations as high as -10 pCi/l. were measured in the basement. Clearly
some of the radon measured in the basement was due to water use, and not to
soil gas entry.
Following this work, the large centrifugal e.\haust fans on the wall
ventilation system v.ere temporarily replaced by smaller centrifugal blowers, and
the sub-slsh system fan was turned off. The HRV was left turned or:. This
\»as to check if the standard of performance could be achieved with the
system under pressure tc r.'c.a i*.:e ehip^c-; h<=ick-Hi'af>i>ig pioblem. A i heck m
March 1986 found thai radon concentiations in the basement during times of no
water use uere in the region of 3 pPi/L, e\ en though the radon concentration
in the air forced up through fioor joints and in the sub-slab system pipes was
500 pCi/L. In April 198G, the HRV was turned off, and the concent! ation in
the basement during times of no water use was in the region of 2 pCi/L. The
concentration in the sub-slab sj stem pipes had dropped to 35 pCi/L, shoeing
that the sub-slab fill had been effecti\el> flushed fioe of radon b;. the an
forced benenth the slab.
In May 1986, the sub-slab s\steiv. pipes and fan wore removed, snd the
small centrifugal blowers we:e replaced b\ permanent w.tl! mounted in-line
centrifugal bloweis of double the capacity. Following 'his, radon concen* rations
during times of no water use and with the HRV turned off, were in the region
of 2 rOi/L. Water use g.'t\e short lived concentration spikes up to 15 pCi/L.
143
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The concentration rose rapidly to range between 30 to 120 pCi/L when the fans
were turned off.
2.4. PHASE 2B
As the radon contribution from water use was greater than the soil gas
contribution, it was decided to study the effect of a radon-m-water absorption
unit m this house. Charcoal adsorption beds were available locall> for removal
of organics from water. One of these units was installed in August 1986, using
the standard charcoal.
Measurements by the Pennsyhania DFR in August 1986 found that th£
radon concentration in the water was, reduced from 67 000 to 3 200 pCi/L b>
passage through the unit. Water usage at this house was a few thousand litres
per day, so an in\entory of several hundred microCuries of radon was expected
in the charcoal. This would give a radiation field of a few hundred inicrorem/h
at 1 metre from the tank.
The radiation field around the tank was estimated by a scintillation meter.
Most of the radiation came from the top 60 cm of the tank, shoeing that the
1.2 m high charcoal bed had considerable spare capacity. Indicated exposure
rates were 3800 uR/h on contact, 380 uli/h at 60 cm from the tank surface, and
22 uR/h at 3.5 m. In the bedroom above the tank the field v%as 20 uR/h
directly abo\ e the tank, but 26 uH/li in the centte of the room.
The Pennsylvania DER placed TLD detectors iri the house to measure the
exposure lates more accurately. The average exposure rules ovei a 33 da\
period were 8200 uR/h on contact, 180 uk/h at 125 cm, tmd 25.5 uR/h m the
bedroom above the tank.
2.5. PHASL. 3
A shielding structure of concrete blocks was built tound the tank. So that
the structure could be removed for access to the carbon unit, the blocks v«oie
not moi tared, but locked together instead with vertical reinforcing bars placed in
the block cavities and tied tn the wall by metal straps. The block wills weie 7
cm thick in total. -\ ."> cm Muck paving slab was used for vertical shielding.
Indicated exposure rales \«erc lediued to 350 uR/h on contact \.:th the
structure, backgiound (9 uR/h) at 3.5 in, and to 7 uR/h in the bedroom above
the tank. The Pennsv lvaiiia UliR placed TLb detectors and found exposure tales
of 300 uR/h in contact with the Lnril<, 30 uR/h at 125 cm, and 11 uR/h in the
bedroom above the tank.
I 1 1
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The radiation field and the radon removal efficiency was measured at
intervals over the winter. The field on contact decreased slightly to about
300 uR/h, and then remained almost constant. The radon concentration in the
well water was lower in the winter averaging about 37 000 pCi/L, and the
concentration in water discharged from the unit averaged 8 000 pCi/L, for a
removal efficiency of 80%.
3. OTHER MEASUREMENTS
Radiation fields in the house and over t e site were estimated with a
scintillometer. The field in the basement was 11 uR/h in the workroom end,
and 15 uR/h by the garage end wall. The field over undisturbed land at the
front of the site ranged from 8 to 12 uR/h. At the rear and the gaiage side of
the house, where the material removed from the basement e\cavation had been
spread, fields ranged between 20 to 35 uR/h.
The average radon concentration measured b> alpha-track detectors over
the periud Lteccmher 19B6 to March 1987 was 2.6 pCi/L in the basement, and
5.2 pCi/L in the living area.
1 \r>
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MEASUREMENTS SU>MARY FOR HOUSE 2
PYIjON AB-5 HOURLY MONITORING
PHASE
MITIGATION
TEST
STATUS DURING
RADON (pCi/L)
COMMENTS
SYSTEM
DATE
TEST
RANGE MEAN
1
Central sub-slab
07/85
Fan off
80-
503
243
over 56 hrs
venli1 ation;
fan on
30-
53
41
over 12 hrs
100 L/s
centrifugal fan
Central sub-slab
08/85
Fan on
12-
56
28
over 46 hrs
+garage wall
ventilation
100 L/s
centrifugal fan
2
As above + IIRV
12/85
Fan on/HRV on
90-
522
250
over 6 daj s*
added by owner
Pan on/I!RV on
26-
692
400
over 0 days**
Fan on/HRV off
13-
1 -176
1 000
over 8 days**
Fan ori/HRV on
20J-
682
439
over 35 hrs**
Central sub-s lab
01 /8C
TcJi on/HRV on
287-
498
397
over 22 hrs
~garage +
Kail on/HRV off
87-
950
345
over 73 hrs
central wall
ventilation
100 L/s
centrifugal
2A
As ebove +
01/80
Sub-slab fan
1J-
90
-13
24 hr fall to
ventilation of
off new fans
15 pCx/L
wall ,'f li>oi joint
on/HRV on
tuo 100 L/s
Sub-slab fan
7-
25
15
over 68 hrs
centrifugal fans
off new fan
on/HRV on
02/86
Pans on/Hrv on
2-
10
5
over 4G hrs
02/86
Fans on/HR\' on
0.4-
8
3
over 4 days L
02/8G
Fans on/HRV on
1-
34
3
over 4 dajs U
Ventilation of
03/8G
Fans on/HRV oi>
1-
17
5
over 4 days
Mill/nnor joint
neglecting
only two 50 L/s
water peaks,
cent rifuga1 fans
mean 3 jjCi/L
on blow
01/8G
Fans on/HRV off
2-
8
4
over 4 rfajs
-------
MEASUREMENTS SUMMARY FOR HOUSE 2
PYLON AD-5 HOURLY MONITORING
PHASE MITIGATION TEST
SYSTEM DATE
Wall/floor joint 05/86
2A ventilation; two
150 L/s
centrifugal fans
on blow
3 Wall floor joint 11/86
ventilation two
150 L/s
centrifugal fans
on blow + radon
adsorption
STATUS DURING RADON
TEST RANGE
Fans on/HRV off 0-4
Fans off/[lRV 19-121
off
Fans on - 1-4
adsorber in
Fans on - 2-8
adsorber out
Fans on - 1-5
adsorber out.
(pCi/L) COMMKVl S
MliAN
2 osor 12 his -
water peaks
to 15 pCi/L
59 over 42 hrs
2
3
3
U - Upstairs measurement
H7
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SYSTEM MEASUREMENTS FOR HOUSE 2
PHASE
MITIGATION SYSTEM DATE
SYSTEM MEASUREMENTS
PRESSURE FLJOW RADON
Pa
(L/s) (pCi/L)
COT-frlENTS
Central sub-slab + 12/H5
gat-age waLl
ventilation 100 L/s
centrifugal fans
As abo\e + central 01/86
wall \eritilation
I 3
10
5
15
10
4 100 Pipe 1
1
2
8
10 700
2 350
4 300
165
Pipe 1
Pipe 2
Pipe 3
Pipe 4
As abo\e +
ventilation of
uall/floor joint ;
t ko 100 L/s
centrifugals -
baseVioard fans onlj
opei ating
01/86
43
68
25
68
40
25
15
If.
32
18
49
24
17
16
280 A
B
1 550 C
D
950 E
F
G
3 8000 H
Thiee fans operating 01/36 25
Tlu t-e fans opei 03/86
17
13
12
9
2
6
14
3 900
5 000
8
14 000
4
700
6">
130
rear basehoai-d
at end Kali
rear baseboard
right of door
rear basebounl
left of door-
rear baseboard
caulked sect.
central fjx>nt_
baseboard
central front
sub-slab fail
ofr
Pj [>? 1
Pip)' 2
IwsemenL air
central K-all
f ront wal 1
near* gar.tge
l'ipe 1
Fan 1
Fan 2
14ft
-------
SYSTEM MEASUREMENTS FX® HOUSE 2
PHASE
2A
2A
MITIGATION SYSTEM DATE
Ventilation of 01/86
wall/floor joint only
SYSTEM MEASUREMENTS
Knll/floor joint
centrifugal two
150 L/s centrifugals
on blow
05/86
PRESSURE
Pa
88
78
30
38
23
15
25
FLOW
(L/s)
1
1-2
18
26
27
29
19
12
21
RADON
(pCi/L)
38
33
4
30
35
COMMENTS
Pipe 1
Pipe 1 3.5 hr
later
general air
Pipe 1, 2 days
later
Pipe 2 capped
A
B
C
E
G
H
I
A: Real baseboard near fan 1.
B: B.vpuss around pipe.
C: Garage basehoairi near fan 1.
D: Tun 2 riser duct.
E: End wall duct.
F: End wall coiner.
G: Front, wall near end wall.
H: Fn>nt wal 1 near garage.
I. Centre of garage duct.
119
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GAMMA MEASUREMENTS FOK HOUSE 2
PHASE
2B
MITIGATION SYSTEM DATE
Wall floor joint
ventilation two
150 L/s centrifugal
fans on blow plus
water adsor-ption
55 L/s charcoal tin it
08/86
MEASUREMENT
LOCATION
Top of well
pres.sur e tank
Top of charcoal
tank
Distance
from
top of
tank
At hot water boiler
Kear of house
Centre line nr boiler
Workshop ilnor
Bdnn front
Brlrm left front.
Rdrm right, front 14
Bdrm centre 26
General upstairs
GA>m FIELD
(uli/h)
09/86
l-l
9
22
40
20
14
11
OO^ILNTS
380 @ 60 cm
1
000
0
cm
1
000
On
contact
20
cm
3
300
On
contact
40
cm
3
800
On
contact
60
cm
2
700
On
contact
80
cm
1
700
On
contact
100
cm
930
On
contact
120
cm
300
On
contact
125 cm distant 80
Contact 8 200
Bedroom 26
@ 3.5 cm
over tank
DER 33 da\ TLD
As abo\e
As ubo\e
As abo\e with
concrete block
shield in**
12/86 At hot water boiler
Workshop dooi
Far end of basement
01/87 Near laundrj
Centre line nr boiler
At DLfi TL.U
on shielding
125 cm distant
Contact
Bedroom
190 cm distant
130 on ihst-uit
13
19
8
8
11
198 On contact
30 62 daj TLD b>
DER
310 As> abo\ e
11 As abo\e
19 As abn\ e
1 1 As alxne
02/87 Wal1
Workshop door
03/R7 Workshop door
Centre line
Bedroom
\t h (11stjui'-f of I m unless othfi'wiso stated
30
1 1
25
15
7
150
-------
GAMMA MEASUREMENTS
IN CONTACT WITH SHIELDING
FCW HOUSE 2
DATE TOP BLOCK I BLOCK 2 BLOCK 3 BLOCK" Y —' BLOCK 5 ELOCK 6
Vater adnorption 55 l./s charcoal unit v.ith concrete block shielding
12/8K
25
73
210
345
360
265
155
01/37
24
CO
172
274
278
194
122
OZ/17
10
60
170
280
295
210
130
03/87
19
G2
200
310
315
245
145
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z<~'-cr
I7-0"
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LOW COST REDUCTION OF INDOOR RADON
FOUNDATION PLAN
_ e*xoH.e>oAj2r^ tvp^
Mitigation system. WALL/6b\& ^UCTIOM
Date: \2/\/£6
PHASE-'
rnAbt-FiMAL
HOUSE
NUMBER
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152
-------
HOUSE 3
Pt'NNSYLA'ANIA DER MEAS I'NEMENTS
Working Lev^l grab samples (KusnetzJ
Heating season average radon (Terradev)
Radon concentration m water
3.00 M;
350 pCi/L.
low (municipal uater)
1. DESCRIPTION
This small twa-stor> house was built in the mid 1970'b on a levelled site o~i
steep hillside in a rurul subdivision near 13o.\ ertown. The ualls arc sidn g.
Heating is by electric baseboards upstair? only.
The basement walls :ne of hollow ...K-iete block. While the house /as
under construction, Lhe uplull basement wall had deflected inwaid, und nad beei
reinforced by two vertical steel begins tied to the floor and jznsts. /-> second
wall uns const rue ted inside the basement to conceal this, and inns along tli».-
uphill v,all and half way along the rear wall. A hollow conciete block coluin.i
feuppoi ting the central beam penetrates the slab.
The end walls und the mterior false wall are open at the top. The sill
plate covers almost all of the block openings on the front and back walls.
Services enter at an opening in the wall which has been cemented closed.
Th«j concrete floor slab was placed in one pour and has some cracking. A
suinp hole in the uphill rear corner of the basement had been concieted o\t_r b>
the owner and had a ventilation pipe installed. The ownei had also installed an
active basement ventilation sjsteni, consisting of an cshaust vent of two
sri eened 5 cm diameter holes thiough the header boai d ai.d siding at one end of
(he basemen', cind n 15 cm duct with n 1" L/s booster fan to supptv flesh .111 at
the other end of the basfenient.
As t1 e walls in this house had peculiar construction (Valine;-, the imtig
-------
was cleaned nut, and tlie slab was found to be poured on bedrock, with 5 cm of
broken rock beneath the slab. "Half-inch" crushed stone vas placed in the hole
and a "4 inch" lightweight plastic dram pipe was installed vertically in the storse.
A beadboard coxer vas cat to fit the hole arid round the pipe. All joints were
caulked airtight with asphalt cement, and the hole was closed with concrete bag
mix.
Piping was run from the riser to a window where a sheet of plywood
replaced the window. A flexible duct passed through the plywood to a large
centrifugal fan mounted outside on a box.
In July 19S5, the radon concentration in the basement reached 1 -178 pCi/L
with the window closed. When the sub-slab exhaust fan was switched on, the
concentration fell to an average value of 520 pCi/L. A lower value might have
been reached, but the dog chewed the flexible hose off the fan. However, the
reduction needed i>as so much larger than achieved that the final value was
irrelevant.
This house wns next door to house 8, where large reductions in radon
concentration hud been achieved by ventilating the walls alone. It was
therefore decided to ex'tend the system to ventilate the block walls as well as
beneath the basement floo: slab.
The tops of the end basement v^alls were closed by stuffing paper intc the
open block voids on both end walls as temporary supports. The \oids were then
filled with mortar.
On the front wall, and the part of the rear wall that was only oi block
thick, strip of wood v'as nailed to the sill plate to extend it o\ er the '.op of
the block voids. This was then caulked to the top of wall with asphaltic
cement.
The space o\er the top of the double walls was very limited, so the lop of
the \>all was ekised b\ nailing a bonid to the joists over the top of the wall.
The board was eaulked along the edge that touched the sill plate. The gap
between the hoard and Ihe tcp of the inner wall was filled with expanding
urcthnne foum. Spaces mound the vertical reinfor« mg steel beams on the end
wall, the beam ptiokels and an\ other openings were also filled with foam.
A 10 » hole was cut into the void of a top course- block near the centie
of eai-h wall sort ion. On the double walls, heth skins of the inner blcc. k \will
uere pt-ntM rated to Heccbt 1 he space between the wulls. N'o fui ther openings
15-1
-------
were mnde into the outer wall orv the uphill side for large cracks here visible
and air flow from the outer wall was assured. The outer rear wall was not as
badly cracked, so a 1U cm (4") opening was also made into the outer block wall.
A 7.5 cm diameter hole was cut in the single thickn js section of the rear
wall.
An exhaust pipe of "4 inch" lightweight plastic drain piping was run fioin
each hole to a "4 inch" header that ran along the central beam and connected
to the existing sub-slab exhaust system pipe.
All wall cracks were filled with a vinyl/cement crack filler. The exhaust
fan vas replaced with a small high speed centrifugal exhaust fan capable of
higher suction.
In August 1983. the radon concentration in the basement with the fan off
ranged from 203 to 213 pCi/L, and fell to between 1 to 2 pCi/L v. hen the fan
was turned on. The uirflow from the front wall was 7 L/s, from the uphill wall
was 9 L/s, from the double poition of the rear wall 8 L/s, ftom the single
section was 9 L/s, and from the garage wall 18 L/s. The floor pipe had a flow
of 2 L/s. The high flows from the garage wall were caused by leakage thiough
mortar joints and cracks in the unpaired section of the wall above grade in the
garage.
2.2. PHASE 2
In \"ov a la> ge wall mounted centi ifugal exhaust fan of higher flow
capacit\ in Ma\ 1986. A "4 inch" duct was extended through the toncrete block
wall, the pl>wood sheet iemo\.ed and the basement window replaced. \s the
weather had turned wal m, futlher measurements weie delaved until the fall.
2.3. PHASI 3
1 :"5
-------
In December 1986 the radon concentration in the basement with the fan
running was ranged from 3 to 10 pCi/L, averaging 6 pCi/L. This was slightly
higher than measured previously, and so it uas decided to replace the vail
mounted exhaust fan with a plastic bodj in-line centrifugal fan of approximate^
double the capacity, and duct the discharge to abo\e the roof line of tne house.
The fan \%as exchanged in December 1986. The wall mounted fa:i i an elbow and a
"4 to 6 inch" adaptor. The fan uas mounted Vv ith the axis vertical, and an "2
inch bj 3 inch" aluminum rainwater downspout uas attached to the fan outlet by
a "1 to 6 uicli" adaptor und a "4 inch to downspout" adaptor. The downspout
ran to above the gaiage roof line. Both the fan and the downspout \>ere
secured to the siding.
In December uith the now fan running Ihe radon concentration in tne
basomont ranged from 3 to 7 pCi/L, averaging 5 pCi/L.
Klov.s and 1 scion concentrations from the garage wall were 16 L/s at
oO pCi/L; from the front \%all uere 6 L/s at 190 pCi/L; from the uphill wall uere
6 L/s at 180 pCi/L; fiom the doubled part of the rear wall 6 L/s at 170 pCi/L;
and from the single section of the rear wall 16 I/s. 'Ihe floor pipe had a
suction of 10 Pa, and a flow of 1.2 L/s at 12 000 pCi/L. Suctions vc.e
respectiv ely lf>, 5, 3, 3, and 9 Pa.
These flo\> s and concentrations v. ere very similar to those measured a year
pr«-\ si.v with the small centi ifugal fan. This suggested that the backpressure
geneiated by the large area change at the fan outlet limited its perfoi manco.
•Mplwi Uaili dosimeters were issued in December 1986 foi f'.nal long term
measurements.
3. OTHER MEASUREMENTS
The radiation field 111 the house ranged from 5 to 11 uR/h, averaging
S uK/h. The field on the site lound the house ranged from a low of 5 uR/h on
the asphalt diiveuaj to 12 uR/h, averaging 9 uR/h.
The aveiage radon rnno'iiti .ition measured bv alpha track detectois o\ er
tVe p^tiod December 1985 to March 1986 uas 4.4 pCi/L in the basement, .md
».7 pCi/L upstairs in the h\ mg room.
Ihe average radon com en I 1 ation measured t>.\ alpha-ti ark detectors o\or
156
-------
the period December 1986 to March 1987 uas 3.5 pCi/L in the basement, and
2.1 pCi/L in the living area.
lo7
-------
MEASUREMENTS SUMMARY FOR HOUSE 3
PYLON AB-5 HOURLY MONITORING
PHASE MITIGATION TEST STATUS DURING RADON (pCi/L)
SYSTEM DATE TEST RANGE MEAN
1 Cent.ral sub-slab 07/87 Fan off 348-1478 1097
ventilation Fan on 234 1352 6G7
100 L/s
centrifugal fan
Central sub-slab 08/85 Fan
+ wall
ventilation
100 L/s
centrifugal fan Fan
off 11- 232 141
on 1- 175 22
2 As above 11/85 Fan on for 0.3-2.4 1.5
three months
12/86 Fan on 3-10 6
3 Centra] sub-slab 12/86 Fan on 3-7 5
+ K-ftll
\entilation
150 L/s
centrifugal fan
COMMENTS
ovei GG hrs
over 25 hrs -
fall to
equil ibriuni
of 520 pCi/L
o\er 26 hrs
rise to
equil i brium
of 21G |)Ci/L
o\er 23 hrs
fall to
equilibrium
of 2 pCi/L
over 48 hrs
over 81 hrs
o\ »r 45 hrs
-------
SYSTEM MEASUREMENTS I OR HOUSE 3
PHASE
MITIGATION SYSTEM DATE
Central sub-slab
ventilation 100 L/s
centri f\igal fan
07/85
SYSTEM
PRESSURE
Pa
94
MEASUREMENTS
HjOW RADON"
(L/s) {pCi/LJ
47
COMMENTS
At fari
Central sub-slab +
11/85
3
7
Fiont wall
wall \ent.ilation
3
9
Uphill wall
100 L/s centrifugal
3
8
Rear wall*
fan
8
9
Rear wall**
13
18
Garage wall
10
2
Floor pi j5e
47
Near fan duct
As abo\e
12/85
150
Uphill wall
9
400
Floor pipe
30
Garage wall
0.2
Ambient
Central sub-slab +
12/86
5
6
180
Front wal1
wall \entilation
3
6
190
Uphill wall
150 L/s centrifugal
3
6
170
Rear wall*
fan
9
16
Rear wall**
15
16
30
Garage wall
10
1
12
000
Floor pipe
* Double
** Single
159
-------
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FOUMPATION WALL
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3.W CUT TO FORM lMf>£I?T£. ON UPHILL «2>ID£ AUDREY
WERE CAULKEt> IM PLACE
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5. FOAM WA«> iJ£>E3>TO SEAL REMAIUIM& &APe>
LOW COST RE0UCT0OW OF BNDOOK
RADON
HOUSE
job
NUMBER
FOUNDATION FLAW
Dato: to/fi/s^
3
SL1U.-SLA& AMP -
Mitigation oyatem: WALL ^UCTIOkJ
PHASE*
FINAL
160
-------
HOUSE 4
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Short term average WL (RPISU)
Heating season average radon (Terradex)
Radon concentration in water
25 pCi/L
8 000 pCi/L
0.252 UL
0.033 WL
1. DESCRIPTION
This one-story brick-faced home with attached garage was built in the late
1950's on a sloping site on the side of a hill in Bechtelsv llle. The walkout
basement walls are of hollovv concrete blocks. The walls are open at the lr>p,
but the voids are partially co\ ered by the sill plate.
The concrete floor slab was poured in two halves and has a Lirge
construction joint running from fiont to back of the house. Pe net rat ions of
the slab include the s-ever and oil linos, the stair stringers, the house jacks, anil
the well pressure tank ^'.-.pport (concrete blocks on their side). There is also a
basement shower and toilet. There are no cracks in the floor. The wnlL/slab
joint opening is small.
2. ACTION'
2.1. PHASE 1
As there were multiple openings in the floor, the miligatne action selected
for demonstration at this site was subslab \ entilation with two centrally located
exhaust points.
A Hilti electric drill was used to drill guide holes on the circumference of
a GO cm circle, and the concrete was broken out with an air hammer.
Jt was found that the slab had been poured directl.v on the bottom of the
excavation, and there was no added aggregate beneath the slab. The an liamnifi
was used to break up the rock, and the holes cleaned out to bedioek. Hie
bottom of each hole was filled with clean crushed stone, and a "4 inch"
lightweight plastic riser pipe inserted vertically. The storie was co\eied with
roofing felt cut to fit the holes, and caulked to the pipes and the edije of the
conctele slab with asphaltic. caulk to maKe the cove an tight. The holes weie
then filled with a bag mix concrete.
101
-------
The risers were connected to a "4 inch" pipe run along the main beam. A
flexible duct ran from the pipe through a plywood sheet replacing a basement
window. A centrifugal fan was attached to the duct, and screwed to underside
of a pl> wood co\ er cut to fit the window well.
When the fan was turned on, very little air was drawn from the system.
The fan ran stalled with considerable vibration and noise.
In August 1985, the radon concentration in the basement averaged 33 pCi/L,
and fell to less than 6 pCi/L when the fan was turned on.
2.2. PHAS^ ?
In January 1986, the concentration in the basepi^nt with the fan on ranged
from 18 to 33 pCi/L, averaging 23 pCi/L. Due to the poor system performance,
it wns removed in l-ebruary 1986, and the site restored.
2.3. PHASE 3
Considerable success had been achieved during Phase 2 at other sites with
poor sub-slab permeability by sub-slab s> stems using multiple point perimeter
suction together with increasing the airtightness of the floor, and a high
suction fan. One of these systems was installed in December 1986.
The well pressure tank was removed from the concrete block base, and the
voids in the blocks were filled with mortar. The construction joint between the
two hahes of the concrete floor slab was cleaned and filled with silicone caulk,
and the hollow house jacks were drilled near the bottom and filled with
expanding ur«Hhane foam. Si\ 12.5 cm diameter holes were cored through the
floor slab about a cm away from the walls. Two holes were placed on the front
and back walls about 1/3 of the way from each end, and one hole was placed
near the centre of each end vail. The holes intersected the footing, but
entered the subslab loose rock fill. A "4 inch" lightweight plastic pipe was
inserted \e:'tically in each hole, and the gap between the pipe and the concrete
flooi was filled with silicone caulk. The pipes were joined to a central duct of
"6 in<-h" lightweight plastic pipe, which passed through the end wull of the
house. A plastic bod\ in-line centrifugal fan was attached to the duct.
-\s success of tins system was not '.-ertain, preparations were made foi eass
installation of wall ventilation if needed. The tops of the walls were closed b>
stuffing fiberglass insulation into each \oid for a teinporar.N suppoi t, and then
injecting e\panding ureth.nie fuam. A "T" was pro\ ided at 30 cm ftoin the fljor
in each leg so that a ventilation pipe could be e-isil> connected into the walls.
162
-------
The fan gave a suction of 225 Pa in all floor pipes, but for 250 Pa at the
pipe closest to the fan. Flows and radon concentrations in the i ear unll pipes
near the end wall were 7 L/s, 160 pCi/L; and near the garage wall \>cre 20 L/s,
40 pCi/L; in the garage end wall pipe were 1.5 L/s, 1 000 pCi/L; in the front
wall pipes near the garage wall v»ere 8 L/s, 2 000 pCi/L; and near the end wal!
were 2 L/s, 620 pCi/L; and in the end wall pipe 2 L/s, 600 pCi/L. Most of
the rear wall of the house is above grade, and the low radon concentrations and
high flows in the rear wall pipes may be due to air drawn from outside beneath
the footing.
In December 1986, radon concentrations in the basement uith tht fan on
ranged from 1 to 7 pCi/L, aveiaging 3 pCi/L. When the fan was tut ned off, the
concentration rose rapidly to i tinge from 10 to 24 pCi/L, averuging 20 p(.'i/L.
Alpha track detectors were issued in January 1987 for final long term
measurements.
OTHER MEASUREMENTS
The radiation field in the house ianged from 7 to 12 uR/h, averaging
10 uM/h. The field on the site ranged from 6 uR/h ovei the asphalt drnewav,
to 12 to 15 uR/h, averaging 14 uR/h over the rest of the site. Soil e\^osed at
a road bank at the top of the hill gave 18 uR/h.
The in erage radon concentration measured by alpha-track detectors o\ er
the period Junuary 1987 to March 1987 was 0.7 pCi/I. in the basement,
and 0.8 pCi/L in the living a'-en.
163
-------
MEASUREMENTS SUMMARY FOR HOUSE 4
PYLON' AB-5 HOURLY MONITORING
PHASE
MITIGATION
SYSTEM
TEST
DATE
STATUS DURING RADON (pCi/L)
TEST
RANGE MEAN
COMMENTS
2
3
Central sub-slab 08/85
\entilation
50 L/s
centrifugal fan
As abo\e
Fan off
tan on
01/86 Fan on
Perimeter sub- 12/86
slab ventilation
150 L/s
centrifugal fan
Fan on
Fan off
7-36
6-30
18-33
1- 7
10-2-J
33
10
23
3
20
o\er 36 hi s
over 36 hrs
still
dropping
over 46 hrs>
over 40 hi-s
over 20 hrs
SYSTEM MEASUREMENTS FOR HOUSE 4
FHASF
MITIGATION SYSTEM DATE
Peiiphernl sub-slab
ventilation 150 L/s
centrifugal fan
SYSTEM N!EASURhME.\TS
PRESSURE FIX*' RADON
12/86
Pa
225
225
225
225
225
250
(L/s) (pCi/L)
2
8
2
20
7
2
620
2 000
1 000
40
160
600
COMMENTS
Riser A fio:it
wall
Riser B front
Ml] 1
Riser C garage
wul ]
Riser D rear
wall
Riser E rear
wall
Riser F end
wall
1G 1
-------
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LOW COST E3EQUCTGON OF BNDOOR RADON
FOUNDATION PLAN
Mitigation ayQtom: •£>u&'^>—A& t>uc.T'ON
Date: \Z/\\;£>z>
P H A S E: F i KAL
HOUSE.
NUMBER
4
165
-------
HOUSE 5
PEN'N'S\ LV WI -\ DER MEASUIiEMEN'1 S
Working Level grab samples (Kusnetz)
Heating season short term average WL (HPISU)
Heating season average radon (Terradex)
Radon concentration in water
0.354 \\ L
0.257 KL
29 pCi/L
4 200 pCi/L
1. DESCRIPTION
This rural single story dvelling was built in the early 198C's on a leveled
site on t'ie side of a hill several miles southwest of Boyertow n. The unfinished
basement has hollow concrete block foundation walls. The front wall of the
house is brick \eneer, the other walls are siding. There is an e\tei nal stjin>aj
to the basement.
The basement walls are in generally good condition but with hoi lzontal
cracking in the kitchen end Mill, and a diagonal crack visible from the outside-
in the front wall at the opposite end of the house. There is no sill plate on top
of the walls, the floor joists rijst directlj on the blocks.
The poured concrete floor slab is in good condition with minor Clacking,
arid is penetrated onl\ b> thr; sewer lines arid tin. house jacks, which ate filled
with concrete. Heating is bj electrtc lesistance baseboard heatcis upstau s, two
forced air electric heatei s in the basement, and is supplemented b\ a coal stu\ e
in the basement.
The owner said there was no pel imeter diajnage tile (weeping tile) around
the foundations, just ciushtd stone. The untrnpped floor drain dischaiges lo
daj light lower ori the site.
2. ACTION
2.1. PHASr 1
Thf> good concrete floor slab suggested that tlu- walls were tiu najor route
of cntrv in this house. The miligativ e aci in chosen for demonstration dt this
was to exhaust the com p-tc block *¦ .ills. It was also the onI\ one of tin*
initial group »• ¦ 111 n significant amount of each basement wall exposed above
gionnd, and so it was decided to test the concept of mounting a small fan in
each will, rather than using a < oiler tion system with a central fun.
1 Cf>
-------
In July 1985, five holes were cut in the exterior face of the uppei courst
of the wall, one in the centre of each wall section. (The rear wall was divided
in two sections b> the door find stepr- to the e.\tei ior). A 1/4 inch di ill was
used to drill twelve holes on u 110 inm diameter circle, and the centre shipped
out with a hammer and "hisel. The holes were sized to take 6 to 4-inih light
weight plastic drain pipe adapters which housed 50 L/s axial fans. The adapters
were screwed to wooden backboards which were sealed with caulk against the
blocks and around the 4-inc.h pipe section. Electrical connections to the f? is
were run through holes bored m the interior of the block walls.
The floor joists in this house rest directlj on top of the walls, so theie is
no sill plate to close the open \oids at the top of the block walls. The options
for closing tiie \oids were to fill them with cement, or else place a co- ei
between ea>_h joist and caulk it to the top of th-» wall. The lattei seemed eas.'_:
for a homeowner to do, and \>as chosen.
The top of the block vails was closed b\ installing roofing felt ' tia/s"
fitted between the joists. The l ear and s'des of the tiavs were stapled to lue
wood and the front portions were caulked to the blocks with asphaltu: i ">ofing
f
cement. A single c oiriponent foam from a small aerosol can was tiled as a
sealant behind the elect ileal pane- with onlj partial si:ixess, dur to the
difficulf,cs in dispensing the foam. The fan had to be used upside down, mid
the i.Iearance to tin- joists and the undeiside ol the flooi was often insufficient
for this. In Jnlj 1935, pi ior to tut rung on the fan.-, the ration concentration
n\ ei figt'd about 1 pCi/I.. I Ins was much lower than e\peeled fiom the PlK
measui ements made duiing the heat.ng season. When the fans were activated the
average c oncenlration rose to about 2.1 pCi/L, and fell \ hen the fans weir
turned off. These lesults were so confusing, that work was suspended i"it|!
Phase 2 of the piogram. Winter measi.i ements were reeded to confirm the
validitv of trie pirvtous high leadings, and evaluate the efect of t!ie coa' sU>\e.
2.2. PI! \S1 2
In No\einbet I'Jft", ne-isu: cmrnts with the coa! stow in opeiation foanj
l :¦ c!i.11 cinit en11 ations in the basement that ranged between 100 to 200 p<"i/I .
Neasut einent s in Deceir.bei l'JSa found thai «. onrentr atioris with the sto\e oft
a\ ci aged abciiit pCi/I. in tin basement, and about 50 pCi/I. iip5l."lis. I he
i.as'.'iin lit di
-------
the basement door w?s left open to heat upstairs, and concentrations averaged
120 pCi/L 011 both floors. This verified the previous high PER reading's, which
were made in the -winter.
A smoke stick check of the closuie trays on top of the walls found many
leakage points, so it was decided to close the walls properl\ with mortar, or
expanding foam in those places where access was loo poor to use mortar. B>
this time, e.\perience at other sites had lead to the conclusion that a collection
system with a central fan would be required at virtually all i»ites, so there was
no point in keeping the individual fan system. A single large centrifugal fan
was noticeably quieter than the 5 small fans operating together. Therefore a
central collection system would be installed m place of the multiple fans.
This work was carried out m January 1986. \s there was no sill plate on
the top of the wall, access of this wall were stuffed with fiberglass as a
tempoiaiy support, and an expanding single component urethano foam injected
into the space. A long nozzle was used to ensure that foam was delivered to
the side of the void awa\ from the opeiator so thut the \ oid would be
i oinpletel.\ closed as the foam expanded.
A standai d "octopus" collection netwo"k with two collection points on ouch
long wall and one on each bhort wall was metalled. The wall col lot. lot s weie "-1
inch" lightweight plastr- drain pipe, and ran to a central collector duct of "!>
inch" lightweight plast'c diain pipe. A lai ge centrifugal xentilr.tor was mounted
on the teal wall of the house in a window well. The weather was too cold for
satisfactory external moi t«i work, and so the wall mounted fans were not
remoxed, but taped closed. IJefore the fan openings wore closed system
pressures ranging from 8 to 38 l'a induced flows of radon concentrations
ranging from 11 to 20 I./s and 40 to 80 pCi/l.. Following closure- of the fan
openings induced flows generally mci eased b> 2 to 3 L/s.
Initial measurements of the sx stein wore made in January 198G. Kadon
concentrations m the basement averaged more than 70 pCi/5 with the fan
running. Investigation found airflows into the walls except at eilliei end of the
front wall over a distaiu e of 1.5 m and radon cuntenl rations in the walls
-------
comparable to those in the house. This indicated that there v>erc radon Miliums
other than the ualls, and that v>all ventilation atone might not be sufficient.
There v*as a marked draft out of the untrappcd floor drain of 10 L/>-. J his
flov. decreased to 5 L/s with the fan off and the basement \*mdoi«s open,
suggesting it was largely driven b.v the temperature difference between the cold
outside air and the relatively warm soil >. urrounding the drain pipe. The ration
concentration in this air was 320 pCi/L, showing that it was connected to the
soil in someway. The diain was closed with tape, and after an hour the
concentration in the drain v»as 1600 pCi/L. Tvideiitly, the dram piping uus not
continuous to the open air and probably wa.i connected to the crushed atone
exterior dram around the house v\nlls.
This provided an explanation for the stmitie results observed in the
summer. Vshon the soil temper..tu re v»as less than the air Lcinpei ature, ail- v-ould
flow dov> n the drain out of the house, and there v^ould be no radon supplj b>
this route, V>hen the five small fans uore turned «.n, they diev. consideri b!e
amounts of air out of the basement via leaks ui the vtull closures. As both
basement doors ar.d vmdo*> a uei e kept closed during the test, the lesultaicr
pressure drop was enough to draw air and radon up the ut'iin into the has-emont
Vihile the fans were running. Once the fans ucre turned off, airflow m the
dram returned to noimal, cutting off the radon supplv .
Ration concentrations in the basement during Kebt uai J 1 18d with the floor
drain closed b> duct tape avf-raged less than 20 pCi/L, confirming thai it .in a
major ladon entry louto, but not the only one.
In March 1986, tho airtightness of the \>atls i>as increased. 'Ihe wall
mounted fans v^ere i emo\ ed and the holes in the ualls mortared closed. 1 he
external portion of the front v%all crack \*as closed to 300 mm belov* guide, and
all of the internal crack v»as filled \»ith silicone caulk. An expanding i ul,l>ei
plug hflii placed in the floor dram. As a test, the large contiifugal e\liausl fan
was replaced b> a smallei centrifugal fan set to blow into the «alls.
Ua<-lun concentrations in the basement varied ftom 1 to la pCi/L, a\ ei a:_;:n^
7 pC'i/I.. Concenti ations in the walls weie 2 to 5 pC'i/1. at this t:rie, md'uiln »i
that fluol rndon cnti J routes were still present. I- lovs s of 3 to 8 L/s ¦wei"'-'
obser.ed under pifssuics of 1 to II I "a.
A large wall mounted centrifugal pressuie fan was ordet ed to s-e>> if hi^he'
pressuc-v in the v>alls would increase the uir flows lii'o the sub-slab .-pa. t , an-1
I GO
-------
decrease the radon supply from the floor. When it arrived, the design was
unsuitable for unprotected outdoor mounting, so the lurge centrifugal ejihuust
fan vas replaced in April 1986. Bj tins time {.lie weather had turned warm, and
further measurements were- deferred until the fall.
2.3. PH^SE 3
In November 1386, the owner complained thnt the coal slo\e in th"
basement uas hard to light and smoked »>hen the e\huust fan was running. It
^ns agreed that it would bo replaced b\ a pressure fun. Fn December 1.986, ^jth
the fan off, radon concentrations m the basement tanged from 12 to 82 pCi/L,
averaging 55 pCt/1 . Following this, n large plastic bodied in-line centrifugal Tan
was installed on the outside of the house below gionnd le\<'l in a window in"]].
This pioduced pressmes of 10 l'a in the walls, with a total air flow of 150 L/b.
Hadon concentrations of about 3 pCi/L vere measured in Ihe an delivery
ductwoik, piesumably due to radon drawn from the exposed soil in the bottom of
the v»indoh well.
Radon concentration in the basement with the new fun on ranged I torn 3 to
4 pCi/b, met aging o pCi/L.
Alpha-track cletecloi s we'-e tabued n. Jnimary l')87 fot final long term
measurements.
3. OTIU R Mfc'AS I !?!A1E\'TS
The i "idint ion fie'd in awd atnurid the iioiiM: ranged from -I to 7 uff/h in the
bct*>< meat, u\ci aging 3 uH/h. On the site the field ranged fiom 6 to 10 uR/h,
avei aging 8 uft/h.
The a\eiai*c rndem concentration ni'.-asni ed b> alpha-trticK detectors over
the period Januar.v tu Nnr
-------
MEASUREMENTS SUMMARY POR HOUSE 5
PYLON AB-5 HOURLY MONITORING
rHASE MITIGATION' TEST
SYSTEM DATE
1 Block wall 07/85
exj iaust ion f i\ e
50 L/s axial
fans
2 As above 11/85
2 As abo\ e 12/85
2 Wall ventilation 01/86
100 L/s
centrifugal
02/86
2 Wall ventilation 03/S6
50 L/s
centrifugal
drain plugged
»t\jal openings
mortar od will
tl^htened
3 Wall ventilation 12/86
100 L/s
centrifugal
3 Wall ventilation 12/86
150 L/s
centrifugal
pressure fan
STATUS DURING RADON
TEST RANGE
Fans off 0-2
Fans on 13- 50
Fans off/stove 60-?00
on contJnuously
Fans off sto\e 7- 85
off 7- 74
Fans off stove 92-117
on 97-130
Fan on 26-153
Fan on 30- 60
Fan on drain 6- 29
taped
Fan on blow 1-15
Fan off 12-82
1 ar: on blow 3- 9
pCi/L.) COMMENTS
MEAN
1 o\er 27 his
35 over '15 hrs
138 o\er 1-1 hrs
56 over 24 hrs R
46 over 24 hrs I
109 over 13 hrs B
118 o\er 13 hrs U
109 over 4 days
51 over 7 his
19 o\or 88 hrs
7 over 4 da\s
55 over 83 lus
over J da.vs
171
-------
SYSTEM MEASUREMENTS FOR HOUSE 5
PHASE MITIGATION' SYSTEM DATE SYSTEM MEASUREMENTS COMMENTS
PRESSURE
FLOW
RADON
Pa
(L/s)
(pCi/L)
Wall ventilation
01/86
8
20/23
75
Pipe A
100 L./s centrifugal
10
11/13
80
Pi po B
-axials open taped
38
34/36
60
Pipe C
10
20/19
60
Pipe D
10
13/16
40
Pipe E
8
13/15
Pi ix- r
V\aJ 1 ventilation
02/8G
10
Drain fan on
100 L./s centrifugal
5
Drain fan off
45
Basement air
320
Dram air
200
Drain air
1 600
Air f rom
capped drain
Wall ventilation
04/86
1
6
3
~Pipe A
50 L/s centrifugal -
1
3
~Pipe B
drain plugged walls
1
1
5
~Pipe C
Lightened
3
8
o
c.
~Pipe D
3
5
4
~Pipe r
1
4
3
~Pipe F
Kali ventilation
12/80
15
26
6
~Pipe -\
150 l./s centrLfugai
15
1 *7
i 1
3
~Pipe B
pressure fan
11
26
7
~Pipe C
18
28
6
~ Pipe !)
15
21
1
~Pipe E
11
21
4
~Pipe F
A: Driveway wall
B: Rear wall
C: Rear wall
D: Did wall
E: Front wall
F: Front wall
* Fan on blow throughout.
172
-------
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foumdatiom
WALL
1-2'- O"
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LOW COST REDUCTOON OF ENOOOR RADON
FOUNDATION PLAN
tolMMIIMtl
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Mitigation syoJem: WALL PRE6t>URi'2ATiOM
Date: AFG.gt,
MOOSE
SUMBE R
PHASE:ntiAL
173
-------
HOUSE 6
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Heating season short term average Wl. (RPlSL'l
Heating season average radon (Terradex)
Radon concentration in water
0.461 WL
0.372 WL
60 pCi/L
14 500 pCi/L
1. DESCRIPTION
This large one-stor> home with attached garage was built in the mid 1970's
on a le\ el site near the top of a hill a few miles northwest of Bojertown. The
exterior walls are all uf brick. Heating is b\ oil fired forced-air supplemented
by a ductless kerosirie heater in the basement.
Half the basement is finished, with a washioom, panelled walls, fireplace,
and n tile ceiling. There is a large open construction joint across the middle of
the basement floor slab in the unfinished half, and the floor is cracked acrobs
one corner of the basement near an external basement entrance. Tins house is
unusual in that the basement head room is increased by a single course of 8"
block standing on Lop of the 12" block walls behind the bi lck \eneer. The sill
plate and joists rest on lop of the 8" block. As there is a gap between the 8"
block and the brick \ oriocr, soil gas can move out of the 12" block* into '.he
house \ la this gap. The lops of the front and bat k block walls are closed bj
the sill plate.
As the trips of the fiont and rear walls were closed by the sill plate, the
mit«gation method selected for demonstration at this house was to exhaust the
hollow concrete block walls. No special effort was to be made to close the gap
between the inner blot k wall and the brick \eneer. 11 was hoped that as tins
gap is often partnlly filled witn mortar di oppings, the leakage iimm of these
walls might be tolerable. The intention was to see how high a stand.u J of wall
closure woald be required.
The top course of concrete blocks ori th.j laundi \ loom end Weill was closed
with a she<'l of inofing felt caulked to the wall top with asphalt ceiiient and
ACT ION
2.1.
PHASE 1
17-1
-------
stapled to the header board. As there were known inaccessible openings into
the walls (the block/brick gap), the sill plate/wall joint was not caulked, and no
work was carried out in the finished portion of the basement.
One hole was cut in the interior face of each of the three vails exposed 111
the unfinished section of the basement. The holes were located as close to the
centie of the complete wall as possible. Collection ducts of "4 inch" lightweight
plastic pipe were installed in the holes, and connected to a cential "1 inch" pipe.
A large centrifugal fan mounted in a box was connected to the pipe by a flexible
duct passed through a hole in sheet of plvwood placed m a basement window
frame.
This treated three of the walls, but. the fourth (garage) wall was concealed
b> paneling in the family loom. A separate fan was installed from the outside
of the wall. A small hole was broken through the concrete gaiage floor, and
exca\ated to the middle of the top course of blocks. An 8 cm diametei hole
was drilled and chiselled through the block. A email centrifugal fan was placed
in the pit over the hole in the wall, and exhausted into the gai age.
In July 1985, the a\etage radon concentration in the basement fell fro"
approximately -10 pCi/L to a\erage 5 pCi/L when the fans were turned on.
The ownei objected to the noise of the small centrifugal fan in the cat age,
find to keeping the gaiage windows open, so it was replaced b\ an external fan.
A pipe w'a^ inserted m the wall opening, a.-.d a flexible duet wua run along the
wall through a pi\ wood panel inserted :n the garage window to a lai ijp
centrifugal exhaust fan mounted in a wooden box.
2.2. PHASE 2
In Januai y 198(1, with both the fans running continually, the ladwn
concentration in the basement ranged from 6G to 107 pCi/L, averaging about
90 pCi/L.
Tlows and l adon concent! at ions were; fiont wall pipe 0 L/s at 10 p('i/i.;
end wall pipe 1-1 I/s at f>0 pCi/L; and rear wall pipe 8 l/s at 30 pCi/1 . 1 lu
garage wall fan disehaiged 28 L/s air at 60 pCi/L. The i adon concent i atior la
the basement at this time was 80 pCi/l.. The lower < oncentratioiis m the «all
exhaust pipes showed that the walls could not be the ei>lr\ route for the ladon
in the b..sement, and that lai ge amounts of outside air weie being duwn .nto
the ssstem. Investigation with smoke lubes showed that the suction in the wall
did not extend mure than l.~> m from each suction point.
175
-------
No test was carried out with the fans off, as the occupants were concerned
that even higher concentrations might result. These concenti ations were
comparable to those measured the previous vinter, and so the system was
ineffective.
To tost if simple rearrangements of the s\ stem could improve the
performance, the fans were replaced by centrifugal fans set to blow into the
vails. In April 1986, with these fans tunning continually, the radon
concentration in the basement \aried from 21 to 36 pCi/L averaging 25 pCi/L.
When the fans wet e turned off, the concentration rose slowly to an aveiage of
60 pCi/L.
B> this time, experience at other sites \ lseinent with the f.m
running continually tanged fiom 8 to pCi/I , averaging 30 pCi/I.. The svstei.i
was modified to a full sub-slab system.
The pipes in'..) tin: walls wen- temoved, and the w,_i!l openings mortared
shut. (The "lees that joined the wall pipes to the floor pipes weie left in
17G
-------
position so that vail ventilation could be added easily to the s\stem if desired).
The plyvkood sheet in the basement window v>as removed and replaced b>
transparent plastic with a hole to allow a rigid pipe to pass through to a large
plastic body in-line centrifugal fan mounted on the ¦wall. The fan s> stoin in the
garage was removed and the hole filled with concrete.
The construction joint in the basement floor was cleaned out and filled
with silicone caulk.
The suctions, flous and radon concentrations with the new fa: in operation
were; front wall pipe 210 I'a, 19 L/s, at 1 100 pCi/L; end uall pipe
175 Pn, 0.2 L/s, at 1 -500 pCi/1.; and rear vail pipe 200 I'a, O.G L/s, at 90 pCi/L.
Radon concentrations in the basement \%ith the new fan opeiating ranged
frum 3 to 11 pCi/L, averaging 5 pC'i/L. Kith the fan off, r.cj.u.enti ations ranged
fro* 24 to 35 pCi/L, averaging 38 pCi/L.
Alpha trade dosimeters u ere issued i 11 Januarj 1087 for final long tei in
measurements.
3. OTHER MCASL'liEMKMS
The radiation field >nside the house ranged from G to 12 ul?/h, averaging
10 uH/h. The field on the site around the house ranged from 6 to 12 uR/li,
a\ erugmg 10 uK/h.
The average ludon cor.rentr.ition measured b\ alph">-track detectors ovei
the period Jamitirj 1987 to March 1987 was 3.3 pCi/L . ' the basement, and
1.1 pPi/l. in the living aiea.
177
-------
MEASUREMENTS Sl^mKY TOR HOUSE 6
PYLON AB-5 110LTJLY MONITORING
PHASE
MITIGATION
S\STO1
TEST
DVIT
ST.VTl'S IJLR1 \'G RADO\' (pCj/L)
Tbvr
RANGL Mr-AN
CONlMF\TS
Wall ventilation 07/85 Fans off
100 - 50 L/a Fans on
centrifugal fans
kail ventilation 01/86 Fans or;
tv%o 100 L/s
centrifugal fans
27-18
3- 8
36
5
66-107 90
over 21 Int.
o\er 27 lus
o\ er 48 hi s
Kail \entilation 01/KS Fajis -_fi
tuo 50 L/s Fa/is off
cei 1t r i fuga 1 f.ins
un bloi>
kali + sub-slab 05/P6 Fan off
\entilation
50 L/s
centrifugal on
exhaust.
Fan r*j
21-3G
31-68
19-98
3-1-1
2.'.
60
70
10
o\ei 5 I lirs
o\er 212 lus
aftei 19 In
ri se t.o
equil ibnuin
o\ci 4 da.\s
o\er 15 hrs
12/36 Fan an
8-52
.<0
over 1
D
38
r.\ ei
In
o\er 1 J his
sys":tm --iF.v-r.rtiw.'.Ts pop hoi se t".
111ASL
MintiA'nON S\S'l 1M D\TL
SYSTEM M!ASlTil>iI NTS
j'VT Shi FvK M.OV> KMX A
I'j (l/s) IjCi/I )
(.¦OMMlVrs
Wal 1 \ent i I it i un t >-<
100 L/s eent. r l fug 11
fans
01 /KG
I'l
i
8
1-1
9
28
50
10
50
60
80
l*ii*% \
I'll"*.1 H
l * s r>o
1 11*.- I >
lV»s^nie.il an
Sub-slab \ cut. i ] at io" l'-'/^*"
150 L/j. cent i ¦ ( no 1
fan
A = Rc.ir i»a 1 1
B - End u-al 1
'J*,[)
1 'i '
210
0.6
r - I ront >-al 1
00
0.2 1 100
19 1 100
Pip<- \
Pipe- n
l'l | x • C
H = Cii.tay,t' w.ll
17 ??
-------
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(TVP 3PuAiE^)
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TEE5 l u-STALLED
(PUTURE WALL
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(TyP 3 PLACES)
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4" C.OUWE6TICM Tc
KAMALFL^XT rC5 PAN
CVERTIC.AL CJI-&C-HAR6-E.)
LOW COST REDUCTION OF ENDOOR RADON
HOUSE
NUMBER
11S1
FOUNDATION PLAN
Date: \-2/\of&£.
6
CWMIItM
Mitigation system: -SlI&^LAEt> 6UC.TiOM
pu a cc •' THCJiJ
PHASE. plMAL
179
-------
HOUSE 7
PENNSYLVANIA DEI? MEASUREMENTS
Working Level grub samples (Kusnetz)
Heating season a\erage (RP1SU)
Heating season average radon .ili.
Sei \ ice entries are closed with mortal.
'1 he concrete floor slab was placed in tun poms v.it!i a lai ge const: nc tion
joint running the length < > T the luiusc, in't is in eseellent icndition ith no
significant < racking. The \w|] piessure "a 11% is mounted or < onei ulc blocks
uhich ponetiate the floor slab. The sla! is also penetrated b> a floor di.un,
th" oil siipplv hn-"', an inlerioi "I shaped' concrett. bloi k uall, and a furnicr
stark of conei i.-te blocks.
The OMi'i said t liat Lhete uas a peri'iieter dtmnige sjstcin, but it v»as juvt
a bed of eiushed stone without piping at the footing Ic^el aioiwul the houst .
The gat lgc flooi diatn and 'lie 1-iundiv sink drain discnaigc mlo this diuin
s,\ sten .
As the top of th<- bdsenvnt >%"alls was geneiall\ <. lose,, the sill p'ate, the
lemedial method seteolej for dcnmiist i a I ton al this siIm v.ib \>.ill wniii.tlioii.
o
ACTION
2.1.
Piivjr. i
180
-------
Die presence of the interior wall and the floor openings would test if floor
openings could be effectively controlled by wall \ entilntion.
System installation started in August 1985. Two 11 0:1 diameter holes were
cut through the interior surface of the ne.\t-to-top course of bloc ks of each
long wall. One hole was cut in each of the two short end walls. Guide holes
were drilled with a "Hilti" electric percussion drill, and the centre knocked out
bj a chisel. Light weight "4 in< h" plaslK. dram pipe was inserted into the holes,
and run in the joist spaces, to a header of "4 inch" plastic drain pipe secured
along the central house beam.
Each end of the header was extended to a window well w hei e ^ flexible
host- passed through a pis wood window cover to a centiifugal fori housed in a
box with a childptoof exhaust pipe.
WIipio the sill plate c.ovred the blo< If \oids (three walls), an asphaltic
sealant was used to close the opening fio.n the house to the wall at the
junction of the sill plate and the wall. Along tin- gaiage wall the sill plate wos
set furthei out, and tin \oids were accessible. Act ess was good to lulf of the
wall, f_~ul the tup \otds were co\ered the!''' b\ nailing a 2 x 2 inch wood strip to
the sill plate o\ er the \oids ai.d (aulknig tli>' gaps w ,th .isphaltic sealei . One
qua! tei of ihe other half '>f the well was <. o\ ered b> .i wooden co\ t closet this procedure. The lop
of I h»- internal blu.k w<»ll was also left open.
In August 1985, when the wall exhaust fans weie tinned on, i .id. n
( on( ent i ations in tin; bas- rncnt fell from appi oximatelv 100 pOi/1. to I , c,/| n>
less th in <>ne d:»\ .
2 2. PHASi 2
The house w.is rerneasu red in Janiiar j and villi the fans inuring,
i adon i one enti'il ions ranue.l from lot) to "01 p( i/l, .i\eriging 2('i pf i/l . \
181
-------
second measurement in January with the fans off ranged from 155 to G25 pCi/L,
averaging 388 pPi/L.
The airflow was from the house into the wall, but the pressure differential
was too small to measure directly ( <3 Pa). The flows und rndon concenti ations
from the walls were; end wall 1-1 l,/s at 110 pCi/L; front wall 12 L/s at
200 pCi/L,and 14 L/s at 320 pCi/L; garage wall 21 L/s at 480 pCi/L, rear vail
17 L/s at 410 p^i/L, and 14 L/s at 170 pCi/L.
These high flows from the walls were interpreted as showing that the
leakage area into the walls was too large for the installed fan system to
produce a significant depressurization in the .soil.
A two stage approach uns proposed to deal with these problems. First, the
fan system w-as to be upgraded. If this was insufficient to ensure that the
walls were always under negative pressure relutive to the house, then the
leakage area of the walls would be reduced. This would involve closing the gup
at the top of the walls between the brick and the header board b> the
injection of e.vpanding single-component foam through holes drilled m the
header board.
The asphaltic caulking was checked with smoke sticks, and leaking areas
were caulked. The collection ducts in the walls were mo\ ed to the foot of the
wall to impro\e their ventilation efficiency, and the central collection duct uas
changed from "4 inch" to "G inch" pipe. The two centrifugal fans weie
retained, but provision was made to replace them with a larije centrifugal
exhaust ventilator of double their total capacity.
Measui ements in March 1086 with the revised system in operation found
radon concentrations in the basement nvoraging 75 pCi/1.. Radon concentrations
oT RIO and 3 800 pCi/1. weie measured in the central "L" shaped wall, confirming
that it was u route of radon entr.v. As a test, the fans were reversed to bluw
fresh air into the walls. Thii would eliminate ihe walls js an entry route, but
would not affect entrj routes in the floor. The overage radon conce n 11 .it ion in
the walls was less than 10 pfi/1., but the basement radon concentration i jiigt-d
from 22 to 88 p('i/l., avei aging 70 pCi/l . Kudori concenti at ions of 8 30(1 pCi/1.
weie mensined beneath the well pressure t
-------
routes of entry in the floor that were not influenced b> wall ventilation.
Depressurization of the walls was not producing sufficient depressurization of
the sub-slab fill to prevent soil gas entry.
These floor entry routes were closed in March. The well tank was removed
and the vertical voids i the concrete block support closed with mortar,topped
with u 15 mm layer of usphr-'tic caulk. The top course of blocks in the interior
wall was removed as the Vk 'ill was not load-bearing, and the voids filled with
mortar. A "4 inch" pipe was inserted into each section at the base, and
connected to the central collection duct. The floor construction joint »as not
closed at this time.
When the fans were turned on again, still in blow, the radon concentration
in the basement initially fell from 50 pCi/L to 6 pCi/L, then rose to 250 pCi/L,
and finally stabilised at 44 pCi/L. This vsas attributed to radon loaded soil gas
being forced from underneath the floor slab by the air blown into the walls.
Smoke tests showed major air flows out of the central floor joint, so there was
a connection from the walls to the sub-slab fill.
The fans v>ere again reversed so that they exhausted the walls, and then
the floor joint crack was enlarged to about 5 mm wide by 5 min deep with a
a.nail abrasive wheel on a har.d-held electric cutter, and filled with a silicone
caulk.
Radon concentrations were about 50 pCi/L with the fans exhausting the
walls and the floor joint open, but fell proinptl.\ to about 15 pCi/L whc-n it was
closed. Evidently the low suction produced in the sub-slab space by the low
suction in the walls was insufficient to levcrse the soil-house flows o\ er
openings in the floor.
As the floor routes of entry in this house seemed to be as important as the
walls, it was decided to alter tlu- s\ stem to test the relative affect of wall a:id
floor ventilation. In April 198G, a concrete coring machine was used to bore 7
hol'-s through the floor slab, one beneath each wall vent pipe. The thickness of
ri ush-'d s'one beneath the slab \aried from 10 cm to 0 em. The wall p'pes were
rut, und Teed into the wall and the floor holes.
The two centi ifugnl fans were removed, the basement windows replaced in
then frames. A single large centrifugal fen was placed in a new window w«'ll
at the re ir wall ai>'.I connected to the central dur t b.\ a "6 inch" plastic pipe
passed tbiough the wall.
Ift3
-------
The 8> stein was initially started with just the pipes connected into the
floor space. The openings into the walls were closed with duct tape. Radon
concentrations averaged 4 pCi/L, and rose to 290 pCi/L when the fan k stem was connected to ventilate both the walls and the floor.
The suction in the pipes into the floor and into the wall was the same at each
location, and ranged from 5 to 10 Pa, set b.v the airflow from the wall. Flows
and radon concentrations in each pipe were; end wall 1 L/s at 40 pCi/L,
floor 0.5 L/s at 3 000 pCi/L; rear wall 4 L/s at 60 pCi/L, floor 0.5 L/s at
12 000 pCi/L; rear wall 4.5 L/s at 25 pCi/L, floor 0.5 L/s at 12 pCi/L, central
wall 10 L/s at approximately 10 pCi/L, floor 0.2 L/s at 1 000 pCi/L. These
flews and concentrations showed that the floor \ eiitilntiou was lemovincc mariy
times more radon than the wall v< ntilation.
In Nlay 1986, average radon conccntrat ions wore 3 pCi/L, and rose to
170 pfi/L when the fan was turned off.
2.3. PHASE 3
The s> stein was retested in rold weather in November 198G, nd isdon
concentrations ranged from 5 to 22 pCi/L with an average of 9 pCi/L and rose
to range between 1G0 lo 310 pCi/L with an average of 200 pf"i/L when the fan
was turned off.
Tin; tests in Ph ise 2 had shown that the sub-slab ventilation portion of the
s.\ stein was producing the gieatost effect. Further tests were conducted in
Hec-ember 1980, the wall entries were dampered to decrease the pipe effort:-,e
pipe diametei fit.in 1 to 2 niches, which increased the average fla.T Midi )'i
from 0 to 21 I'a, and made the flows from the wall and flour appi r>\im.itel>
equal. The flows and radon concentrations in the wall a.id floor pipes weie;
end wall 12 L/s at 10 p<*i/l , floor 16 L/s at 330 pCi/L; front wall 22 l./» at
30 pCi/L, flooi 12 L/s at 5r>0 pCi/L; rear wall r> L/s at 130 pCi/l , flooi 7.'"> L/s
at 1 800 pCi/l : real wall 17 L/s at 7 p(*i/L, floor 7 L/s at 1 COO pCi/l ,; and
184
-------
central wall 13 L/s at 7 pCi/L, floor 11 L/s al 1 400 pCi/L. The dainpeis
produced a highly turbulent nnd asymmetric flow in the pipes, which makes
measurement of the average velocl'v difficult. The calculated values ore
probably biased high.
The average radon concentration in the basement fell fiuu. 8 pCi/L to
5 pCi/L when the dampers Here installed.
Alpha Track detectors were issued to measure the long term average radon
concentration during the heating seHson.
By February 1987 experience at other sites had been that sub-slab
ventilation with high suction had reduced radon concentrations in other houses
with concrete block walls. It uus decided to investigate effect of converting
this house to a high suction sub-slab \ entilation system.
In late February 1987 the svstem fan was replaced b> .i large plastic bodied
in-line centrifugal fori. New dampers were fabricated that vould completed
close the wall entry pipes, and these were installed in March 1987. Closure of
the wall pipes increased suction in the floor pipes from 35 Pa to 220 Pa, but
radon concentrations still aveiaged 4.5 pCi/L after the change. FJous and
radon concentrations in the floor pipes were; end wall 7 L/s at 670 pCi/L,
front v>all 15 L/s at 110 pCi/1., garage wall 14 L/s at 2 400 pCi/L; rear wall
7 L/s
pipe connection into the wall, the radon concentration increased rapidl> to
range between 16 to 48 pCi/L, and average 26 pCi/L. Suet.on in all the flout
pipes was 30 I'a, and anflou was definitely into the walls. As this was a major
decrease in performance, the flows and rt.don concentrations in the pipes woie
remeasured. In the ond wnll pipe the flow was 8 L/s at 4 pCi/L, flooi was
13 l./s at 250 pCi/L; front wall 4.5 L/s at 5 pCi/L, floor 10 L/s at 230 pCi/1 ;
gar»g<; vail 6 L/s at 35 pCi/L, floor 12 L/s at 2 000 pCi/L; cential wall 20 1 /s
at 50 pCi/L, floor 1.2 l/s at 6P.0 pL'i/L. The high turbulence generated bv the
damper made it difficult to determine the average air velocity, so the calculated
flows are biased high. However, the airflows and radon concentrations out >.>T
the sub-slab space aie sinulai in each case, so there was no oh* ions le.ison foi
the marked mciease in tlm basement radon coin entration.
The sv stem wis pr?rmanenllv returned to a sub-slab v entilal inn sv sLem in
Mai < li 19R7, bv closing all the wall diimprrs. This im ceased the mii.Iioii in the
-------
floor pipes to 220 Pa. Flown and concentrations in the floor pipes were; end
wall 6 L/s at 680 pCi/L; front wall 12 L/s at 130 pCi/L, and 12 L/s at
270 pCi/L; garage ual! 20 L/s at 5 600 pCi/L; rear wall 13 L/s at 2 200 pCi/L,
find 9 L/s at 2750 pC /L; and central wall 5 L/s at 590 pCi/L.
Following this the radon concentration from in the basement ranged from 1
to 10 pCi/1., averaging 4 pCi/L.
3. OTHER MEASUREMENTS
The radiation fields around and inside the house were 8 to 13 uR/h
averaging 11 uR/h, on the site, 6 uR/h oil the asphalt driveway, and 7 to
10 uR/h on the concrete basement floor, a\eraging 8 uR/h.
The average radon concentration measured by alpha-track Selectors over
the period January 1987 to March 1987 was 4.1 pCi/L in the basement, and
2.8 pCi/L in the liv ing area.
1HG
-------
MEASUREDIENTS SENARY FOR HOUSE 7
PMjON .Mi-5 IIOLRLY NON'ITOHIN'G
P1IASE M1TIGATIOV TEST STATUS DURING RADON (pCL/L)
SYSTEM DATE TEST RANGE MEAN
COMMENTS
'•mil ventilation 08/85 Tuns off
two 50 L/s Fant» on
centrifugal fans
-HO
¦ 12
16
o\er 21 hrs
over 21 hrs
01/86 Fans on
Funis off
100-"50
155-cr:
207
38B
o\er 1 iJ a > s
over 1 da\ i
03/86 Fjuis on 50-100 75 o\er 18 hr^
Fans rcneised 51- 90 67 o\er 18 his
to bio.-
As alxne + writer 03/86
t.uilt pl.ttfoi-n
sealed t central
wall \entilation
Tans on blow
Fans on blow
22- 88
13- 56
6-240
2- 50
70
•10
63
15
o\or 1 iia>s B
over 4 da>s U
o\ er 4 rr
l- o i
5-287 126
o\cr 11 hrs>
Mil! r:si*u:
¦f'.w 16 hrs
1VT
-------
As above - tujx.- 05/86 Fan on
on
As abo\e -tape
off
Fan on
Sub-slab +wull 05/86 Fan on
ventilation Fan off
100 J./s
ecnt.ri fu^al fan
1- 7 J
o\er -15 hr-s
2- 7 J
o\er 31 hrs
1-7 3
17-169 91
over 58 lii's
over 19 In
188
-------
MEASUUIMKNTS SUMMARY FOR HOUSE 7
HI/A' \!3-5 HOLTiL\ MONITORING
PHASE MITIGATION TEST STATUS DLTJI\G RADON (pTi/L) COMMENTS
SYSTiM DATE TEST RANGE MEAN
3
Sub-^lub + wall
11/86
Fan on 5-
22
9
o\ or
50
von 1.1 lation
1'an off 1G6-
340
259
o\ cr-
38
100 L/s
centi l fugal fan
3
As above + >-Till
J 2/8G
Fan on not G
- 10
8
ove i
13
oiit i les (?-'i core
-------
SYSTEMS MEASUREMENTS FOR HOUSE 7
PHVSE MITIGATION SYSTEM DATE SYSTEM MEASUliEMENTS
imSSURE FLOW liA!X)\'
I^a (I./s) (pCi/L)
COMMENTS
2 V*al] \entilation two
50 L/s eentrjfugal
fans
01/86
3
3
•1
15
4
5
35
25
14
12
14
0.21
17
14
12
39
110
200
320
480
410
170
200
PI-end wall
P2-front wall
P3-front wall
Pl-grge wall
1'5-rear w-al 1
P6-iear wall
At front wall
fan
At end wall
fan
As Hbo\f fans 03/86
i^NeLst-d to bloi.
Sub-slab + wail 05/86
\entilation 100 L/s
centnfvvial f.iris
18
PI
16
1*2
19
re
10
7
pi
wal 1
8
2
160
pi
floor
10
4
25
P2
wall
8
0.
5
12
P2
floor-
8
3
P3
wall
6
1
P3
floor
<)
4
40
PI
wal 1
8
0.
5
3 000
P4
f loo:
5
5
P5
wall
5
2
P5
floor
8
1
P6
wall
5
0.
, r.
3 000
PC
floor
5
10
30
P7
Wall
3
0,
,2
1 000
P7
floor
100
-------
3 Sub-slab + wall ]2/86
ventilation 100 L/s
centrifugal fans -
va]] entries dampered
to 2" pipe
12
10
PI
wall
16
330
PI
f i oor
11
P2
uall
8
P2
flooi
10
36
P3
wall
12
550
P3
Floor
3
130
PI
Willi
7
3
800
PI
floor
11
P5
i.all
9
P5
floor
F
7
P6
uall
n
1
1
600
P6
f]oor
13
73
P7
wall +floor
11
1
•100
P7
floor
5
25
8
23
8
23
3
23
3
23
3
25
25
23
101
-------
SYSTEMS Mlv\SUREMENTS TOR HOUSE 7
PH.VSE MITIGATION H%'STI:M DATE SVSTEM MEASfRIMI^NTS OC^Plt'NTS
PRESSUNE FLOW IJADOV
Pa (L/s) {pCi/M
Sub-slab + uall 03/87
8
PI
wul I
ventilation 150 L/s
250
7
670
PI
floor
centrifugal -wall
15
G
P2
Wall
tjiitiies dampei ed
238
3
130
P2
1'loor
full> r. lt>s>ixl
7
P3
wull
225
14
1 to
P3
floor
20
P4
Jrtill
225
14
2
400
P1
floor
6
P5
wall
238
7
G20
P5
I'loor
9
P6
will
188
7
2
300
P6
floor
200
11
58
P7
walL+floor
213
3
3b0
P7
floor
As aho\ e with 03/87
8
8
4
PI
wall
dampers with drawn 1"
35
12
250
PI
floor
15
8
13
P2
i.al I
35
10
19
P2
fl our
10
•1
5
P3
wal L
30
10
230
P3
floor
10
6
35
1*4
1
30
11
2
000
P4
floor
5
7
4
P5
wal 1
33
1 I
420
P5
floor
8
9
1G
P6
wal 1
35
8
1
200
l>fa
floor
38
20
47
P7
wall +floor
30
1
G80
P7
floor
S\jh-slab vent i Jation 03/87
200
G
G80
PI
150 L/s <.entr.) fus*al
250
12
no
P2
fan
225
12
270
P3
200
20
5
600
PI
238
12
2
200
P5
238
8
2
7 50
P6
225
5
590
P7
F': pi j>o
102
-------
ROLTL- OF ENTRY X1EASUREME\T FOR IIOL'SL 7
P11A3E
M1T1GATLON SYSTEM D.\TF
SAMPLE LOCATION
RADON (|)Cl/L)
Wall ventilation two
50 L/s eentr 1 fugal
f aris
03/86 Basen.ent air 77*
Central "L" wall Jong lnnb 810*
Central "L" wall r.hui t limb 3 800*
As abo\e with fans 03/86 Beneath pressure Lank 8 300
reversed to blow CentiaL wall long limb 900
Cenc al wall short limb 1 000
Roar wall near end wal1 50
Front, wall neat end wall 2
Gara^'-* wall near front wall 8
F looi tlrain 330
Hasrmi'nt air 70
* Crab sample
KM
-------
l©
Q_*bTE£\_ BEAM
! SLAB
tsl E I FAK!-,
KEMCVEP J
4 Pve
/T FVC
AcpPvr:
THRU i^A&
&U30C I
WAUL
¥
*- CHIMWEV
wsvipovt"— -v
TVP.
thfu6wb^
4*4>Pvc
TWSra «SLA^
6d>FVfc
/-A"a> pvc
6."UO£-K F»L/NlCiX-
TH7M WAL.I—
TYP.
All **' £7FF
W/ METAL.
tPK^MPEf^S .
(7 PL-&C.E.-5*TVS?)
^KAfcJALF^LAKT
KG R\.M
(VESmcAL)
METAL
'AREA WAY
PHA-ftE I RAM REMOVED
NOTE5: |. LCKJ6-lTUC,lM^L C^)6»"n2UC.T10H JflMT .N FT-tfC^
^LA& &EAUE& WITH -ShL-i^CME SEAIAMT
2. iMOlVlDl^AyL. ^L_A& FRACTUeE-S, ^FAi
2>. WATEJ2 -TAMfcC ¦SUPR5(?T ©UJOC CCLL-5 f=fL_i_EC->
WITH k/lOKTAR:
4. "£»TAkfR EVJO WALL e>EAJ_EC> WlTMW«5D ¦S»Tia\T> AT
*S>(L.L FtlATE:. OPPOSITE EMt- WALL -SEALEb
WITH R3LYURETHAWE. .
LOW COST REDUCTION OF INDOOR RADON
HOUSE
NUMBER
BS
FOUNDATION PLAN
Dato:£/25^£
7
Ipimihii
Mitigation system: 51J55LA& -SL-k^-T'C?M
PHASE:
194
-------
HOUSE 8
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (kusnetz)
Hunting season average (RFISU)
Healing season radon average (Terrado.)
Radon in water
1.704 KL
0.128 KL
183 pCi/L
low (municipal v.ater)
1. DESCRIPTION
.Thia two-storj house with attached garage was built in the mid 1970's on u
sloping site on the side of a lull in a rural subdivision west of Bojerlown. The
wills are all covered uilh siding. The basement walls are of hollow concrete
blocks, and there is a single concrete block pillar in the centre of the basement.
The uphill side wall has horizontally cracked mortar joints. The block voids uii
the front and back \\alls are covered by the sill plate, but are full\ open on the
side v»a31s. There is a large opening around the se\%er exit in the front w.ll.
The floor has minor cracking. Heating is by electric baseboaids upstuirs.
2. ACTION
2.1. PHASE 1
As the house i«as small, tlie lop of the basement v.alls relatively accessible,
and the floor in good condition, the mitigation measure selected for
demonstration at this house \%as ventilation of the basement block ^alls.
\\here the block voids at the top of the end walls uere roadil> accessible,
they verc sluffc-d \%ith paper and then filled with mortar. Where access *wis
poor, eg behind the electrical panel, the voids were stuffed x«ith paper and
expanding iirethane fonni wn.s injected uith a long Iio/zle.
The sill plate- v»as caulked to the lop of the front and back \>alls \»ith
asphaltic loofing caulk. In addition, the large opening in the \.all around the
si'kcr, and other holes round service entries, woi c sealed v»ith e\p:sndnn?
iiret lian<"? foam.
\ hole v»as I'lit in !is
inserted in each hole. The pipes \»ere connected lo a loop of "I men"
ItLjhlueigli! piping that i an i omul th«- basement peruneit»r and terminated in l^o
i or.
-------
flexible plastic ducts run through a plywood sheet placed in a basement window
opening. Two centrifugal fans installed in wooden boxes were placed outside,
and connected to the flexible ducts. This was a temporary set-up to allow
changes to the system.
At first the fans were set to blow into the block cavities to test the
feasibility of driving radon-bearing soil gas in the walls back into the soil. In
July 1985, the radon concentration in the basement fell from 150 pCi/L to
1 pCi/L when both fans were turned on.
Pressurising the walls revealed a number of significant cracks and openings.
These were all caulked or mortared, and the fans were then reversed to
investigate tho relative perfoi mance of the system with the walls under suction.
Exhausting the walls was the preferred solution,since blowing cold outbide air
into the wall would make tho interior surface cold in winter.
In August 1985, the basement radon conceritiatiun with t\\0 fans in exhaust
averaged 2 pCi/L, and with just one fan in operation, averaged 3 pCi/L.
2.2 PHASE 2
In December 1985, tho basement radon concentration with one exhaust fan
in operation ranged from 2 to 5 pCi/L, av eraging 3 pCi/L. The flows and radon
concentrations from the garage wall were 19 L/s, 200 pCi/L; the front wall
12 L/s, 220 pCi/L; the uphill wall 6 L/s, 1 800 pCi/L, and the ifar wall 10 L/s,
110 pCi/L. Suctions were respectively 18, 5, 8 and 5 Pa.
Alpha track detectors weie iss-ued in December 1985 to check on tlu- longer
term performance of the system.
In Ma> 1986, the temporary fan was lemoved. The basement window was
replaced, and a large wall mounted centrifugal fan was attached to I he sj stem
instead. No measurements were mude of the system performance as tho weather
had turned warm by this time.
2.3 P1IASF n
In the f.ill of 1986, it was dec idod to replace all Ihe wall mounted
centrifugal fans by plastic bodied m-line centrifugal fans of approximately
double the capacity. At the same time, the air discharged fiom tho fan would
be ducted to the roof line, father than i eleased aL ground level. Tins it as done
in December 198G. The wall mounted fan was removed, and the in-line fan
attached to the "I inch" piping b.\ an elbow and a "1 to G inch" adaptoi . The
fan was mounted with the . . vertirvil, and an "2 inch b> 3 ips_h" ahiinimur
lilG
-------
rainwater downspout was attached to the fs.i outlet by :i "J to G inch'' adaptor
and a "1 inch to downspout" udaptoi. The downspout run to abme the parage
i oof hue. Both the fan and the downspout were secuied to the siding.
Villi the new fan in operation suctions at the stills wore approximately
equal and ranged from 9 to 13 l'a. Flows and radon concc-ntiations from the
garage wall were IS L/s at 170 pCi/L; from the front wall were 12 L/s at
170 pCi/L, fiom the uphill wall were 7 L/s at 1 -100 pCi/L, and from the tear
wait 8 L/s at 3 20 pCi/t..
These results were \ery similar to those o'ot lined a j ear previously with
just a single small centrifugal fan, and suggested that the backpressure on the
fan caused by the i est i ictioii of the discharge pipe was a majo: '.imitation i.n the
fan perfoi mance .
Basement ladon <.onct;v I inch P\ C pipe. Suctions and flows were; m>_i eased !o 2fi Pa and 27 L/s fo:
the uphill wall and 10 Pa ind 10 L/s foi thv reai vail. L'ndor those conditions,
radon concentrations m Ihc- basement ranged fiom 2 lo 12 pCi/L, averaging
C pC'./!.. Uiit n the disihat ge iisei vs.is nTiov ed tin' radon lev i.-ls langed fioii. 0
to " pCi/i., .relaying 2 pCi/L and when the dischai ge was replaced, ranged from
1 to 0 pfi/1. a\eraging ^ pCi/L
fan test ;n \pi il 1987 showed a suction of 93 Pa m the fan riser
providing a flow of 31 L/s uhoicus the fan o\haust was measured at 238 Pa.
n. onirN xcASL'ier.^Ji.Ms
""he ladintion fluid m and aiound the house landed ftoir 6 to 12 u!\/!:,
averiging 9 uR/h in t h'; bascini til, with 'lie higlsei leadings found i lose tn l!>e
walls. On the sit'. , tin rield Minted fio.r. C tu 10 uli/h. av e: iging 9 ulJ/h.
Thf average radon concentration measured h\ alpha-tr.n. lv detectois ost:
the ; t-i 'od Dei embci 19P~ to >'ai t.h 19Fr> was 3.1 pCi/L in the basement, ~md
1^ ' i1 ik i tli" 1. \ ing cii ea.
1 97
-------
The overage radon concentration measured by alpha-truck detectors over
the period December 198G to March 1987 v>as 3.9 pCi/L m the basement, and
1.8 pCi/L. lri the li\ ing area.
108
-------
MEASUREMENTS SlfrMARY TOR HOUSE 8
PYLO\ AB-5 HOURLY MONITORING
PHASE MITIGATION TEST STATUS DICING RADON 3 o\er 20 hrs
fans on exhaust
2 As above 12/85 One fan on 2-5 3 over 53 hrs
3 V»'all ventilation 12/86 Fan on 4-9 6 over 45
150 L/s hrs
centrifugal
(downspout
discharge)
3 As above v*ith 03/87 Fan on 2-12 6 over 90 hrs
modified
discharge
3 As above with 03/87 Fan on 0-3 2 over 29 his
free dischaige
As above 03/87 Fan on 1- G 3 over 67 hrs.
discharge
replaced
199
-------
SYSTEM MEASUREMENTS FOR HOUSE 8
PHASE
MITIGATION SYSTEM DATE
SVSTEM MEASUREMENTS
COt-frlENTS
PRESSURE
FLOW
RADON'
Pa
(L/s)
(jjCi/L)
2
Wall \entllatlon
12/85
18
19
200
A
50 L/s centrifugal
5
12
220
B
8
6
1 800
C
5
10
110
1)
3
Wall \entilatLon
12/86
15
18
170
A
130 L/s eentilfugal
10
12
170
B
fan
11
7
I '100
C
9
8
120
D
3
As al>o\ <•
03/87
25
27
A
15
16
B
15
11
C
10
10
D
As above
0-1/87
93
238
54
Fun riser
Fan exhaust
200
-------
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WOUES-
LOW COST REDUCTION OF INDOOR RADOfi
HOUSE
NUMBER
FOUNDATION PLAN
Mitigation system: wall -S u err \ o S-4
Date: \OA3t\S&
PHASE: FlUAL
e>
201
-------
HOUSE 3
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Heating season average (RP1SU)
Heating season radon average (Terradex)
Radon concentration in water
533 pCi/L
29 400 pCi/L
0.340 WL
C. 173 WL
1. DESCRIPTION
This single story house with attached double garage was built in the early
1980's on a sloping site at the side of a ridge in n rural subdivision near
Boyertovn. The front and end walls are brick veneer, thp rear wall of the
house is siding.
Tlie walk-out basement walls are of concrete blocks covered by pol> styrene
beadbuard sheets, except for one quarter of the basement, hoi e there is a
laundry room and a bathroom, both with plasterboard walls.
Heating is by electric resistance baseboards upstairs, supplemented by a
fireplace. In the basement there is a large conciete block and brick fireplace
structure rI the garage end with & wood stove vhich also supports the first
floor fireplace. Jt rests on the slab, lather thdn penetrating the floor to a
separate fooling.
cracks were evident in those parts of the walls where the insulation
panels were partly removed. The walls are penetrated b.\ service pipes for
sewage and water. The sill plate partially covers the cavities m the front und
rear block walls, and access is poor. The blocks are completely open at the top
along the bathroom, laundry and garage walls. There is a.ji internal conciete
block wall supporting the recessed front wall at the porch.
The poured concrete slab has no construction joints, iu. cracks and no
individual floor drains, but is penetrated bj hollow steel house jacks. The well
pressure tank is in a small nlcov e vvith a sand and brick flooi.
There is an interior perimeter drain (freach drain) about •! cm wide between
the walls and the slab perimeter around the entire perimeter of the Kiseweiit.
2. -\CTI0N
2.3. PHASE 1
202
-------
As this house v*as one of the few v%itli an interior drain, the mitigative
method selected for demonstration at this house wus integrated ventilation of
the french drain and the basement walls.
The lowest 50 cm of the insulating headboard and fruming on the basement
walls was rut away to expose the lowest course of block. Holes of 10 mm
diameter were drilled just above the floor level into each block void 111 this
course. Locally marvifantured sheet metal covers wore placed over the french
drain slot and the drilled holes, and secured to the \-»ll and floor by screws
placed in previously drilled anchor holes. An asphalt roofing caulk v.us used on
the v.all and floor junctions, to make the cover airtight.
Continuous cuvci sent ions uere placed along the entire front wall, the
interior uall, and on aboul 50% of the end and rear v»alls. The drain in the
laundry and bathroom area uns not covered, for this v^ould require removing the
plasterboard and framing. '1 he stairwa.v at the other end of the basement is
boxed iri and finished u ith plasterboard. The french drain was not covered in
this area foi the same reason. There was a large sliding glass door in the
c-jntre of the rear v*all. The drain v\ns filled in this area.
The dram v.as open behind the fireplace structure, but could not be reached
to put a cover over it. Cement gtout was pruned through tubes into this
section of the flench drum, and into smalt openings in the concrete bloc':
columns qupporling the fn cphco structure on the floor above.
There v\«re four separate cover sections. These VNerc connected in pairs bv
"4 inch" lightweight plastic piping to a temporarv fan installed at each end of
the basement. Pipes ran from the covers vertically to the joists, and fiom
there to connect via a flexible duct passed thiough plywood panels in ?ht.-
laundr.v and garden uindo^s with small centrifugal fans.
Where possible the tops of the block walls \sero closed by uood stiips
caulked to the sillplate. Access vas too poor to close the tops of the
balhroo laundr.v and garage vsalls in this manner. 1-or th-'se ualls the top
block voids were Tirst stuffed ith paper for support, and then filled i*)th an
expanding single component urethane foair.
The sand arid bi irk flooi of the well lank nli ov e uas lemoved, exposing a,
'ipei'ing in the floor slab. Roofing felt Vvas set into the opening and c aull.i d
into plate. \ nielal con er connected to the front wall covt-i v»as placed over
the iiull-f'oor joint in this area, and the bricks replaced.
20T
-------
While the cold room floor was being removed, a thunderstorm took place.
When lightning struck a hilltop about 300 m away, one of the workmen
collapsed. It was believed that he was in contact with the metal well-head
equipment, and the circulating ground currents induced by the strike flowed
from the exposed soil beneath the building, through the man, and into the well.
He recovered within a few moments, but was taken to hospital. There was no
sign of permanent damage from the experience.
In August 1985, when the fan.-i wore turned on the average radon
concentration fell from about 250 pCi/L to approximately 5 pCi/L in less than a
day.
2.2. PHASE 2
In November 1085, radon concentrations in the basement with the fans
running were varied from 7 to 40 pCi/L, averaging 20 pCi/L. Moisture m the
soil gas was condensing in the flexible hoses to the fans, and reducing the
airflow.
Additional work was catried out in January and February 1986 to improve
the fans and the system performance, and to extend the covers over the seel ions
that had not been treated previously. The temporary plywood panels taken out
of the windows and the small centrifugal fans were removed . The> were
replaced b> two large wall mounted centrifugal e\haust fans, and permanent
metal ducts weie mounted on the inside surface of the walls to connect them to
the covers The caulking and wall closures were examined, and improved whcie
needed.
The lowei 18 cm of the plastered walls beneath the stairs and in the
laundr.v room was cut off, holes were drilled in the lower course of the bloik
wall, and new covers placed over the french diain exposed in these areas. The
drain was now covered around the house perimeter except for the filled section
behind the fireplace and a section behind a shower stall in the bathroom.
When the new fans weie turned on, the ov* ner complained that his wood
stove Wr.s hard to light, and smoked, and that the upstairs fneplace had smoked
badlv - something that had never happened before. Turning off the f.-ns
stopped those problems. While the system whs operating <_oncenti ations ranged
from 2 to f2 pC'i/L averaging 20 pCi/I .
The fans weie obv lotislv depressu rmng the house, which was a
disappoint merit as a large effort Had been m.ide to decrease th«. w-ill leak.ige
201
-------
area. Detailed investigation, including removal of beadboard panels from the
walls, found that the walls were unusually porou9. Most of the concrete blocks
in the basement vails were typical modern &>.eara cured blocks of low porosity,
but there were still a large number of blocks that resembled cinder blocn. They
had a very coarse aggregate, and a minimal amount of cement paste holding the
aggregate together. Individual pores were as large as 3 mm in diameter. Smoke
tests showed that air was drawn through the entire face of the block. As luck
would have it, the ducts to the fans covered a number of these blocks, and
there whs a considerable airflow into the duct through the blocks. Pressures in
the five risers ranged from 15 to 43 Pa and provided flows of 16 to 53 L/s of
air with an average concentration of 10 pCi/L at ^ time when the ambient air in
the basement was approximately 8 pCi/L. Measurements al various placos aiong
the baseboard duct provided ranges in pressure, flov and concentration of 1 to
8 Pa, 0.2 to 10 L/s and 25 to 100 pCi/L.
Since backdrafting the combustion appliances is dangerous, this state of
affairs could not be allowed to continue. As n short term measure, the exhaust
fans wpre removed, and replaced with small centrifugal fans set to blow into the
vails.
In March I98fi, when the neu fans wore turned on, radon concentrations iii
the basement fell from 300 pCi/L to 60 pOi/L in a few hours, and then
fluctuated betueer. 30 to 150 pCi/L ox'er the next da\, before stabilising at
about 8 pCi/L on the third day. Further ineasui enients in March found that
concentrations varied between 5 to GO pCi/L, averaging 20 pCs/L. 'I his \.ater leakage onto the basement floor beside the bathroom. riv
concern uas> that the drain had become blocked in (his aiea, and v>uter leaking
into the block uulls v>as filling the drain and seeping out from Len'Mth Die
cover.
The cover »'as removed fioin the draic in the area where the water h td
entered, and the dram was found to lie unobslru< ted. The drainage u as checked
b> running a hosif into the drain at a rate of 10 1/min. The vater ran a\*u>
20 r>
-------
beneath the slab at this rate for 2 hours, and so it did riot seem likely that the
cause of the leakage was the drain filling with water. There was no sign that
the blocks behind the cover had been wet, for fine drilling dust was still visible
in the bottom of the drill hoie.'i into the block voids. The cover on a section of
the front wall was removed. The drain there was completely dry, with no s.gu
that it had ever had water in it.
The cos er ended at a block in the (entre of the end wall which had
watermarks on it. This was directlj beneath the house beam and was filled
with cement. The site is steeplj sloped from front to rear at this end of the
house, and the brick veneer is stepped to follow the grade. In places the soil
was well above the brick, so surface water could enter the wall at the mortar
joints, and drain down inside the block wall.
It seeined likely that the cause of the water 011 the flooi was that surface
water had entered tin- end wall, was prevented from draining to the footing b\
the cement in the block \oid, and had leaked out of the wall abo\e the covei .
The eo\ er prevented the water from entering the drain. The floor in this area
was level, and so quite a small amount of water would make a large puddle.
To pre\ent this from happening again, the co\ er was shortenei b\ 15 cin to
e\pose the drain in this ai ea.
This experience suggested that perhaps it was unwise to di ill hol<_*s into the
lowest course of blocks unless the drainage beneath the coders was known to be
good. To judge from the wat>-i stains in some houses, the walls could leak badly
enough to fill some of the lowest blocks with water. If thei e were holes :.ito
the \oids, rathei than this water being stored until it dt amed away or
evaporated, this water might fill the soil gas collection s,\ stem, and then leak
out onto the flooi .
In Maj 1980, the new Moweis were di-Ii\ered, and were wall mounted under
a pioteiti\e metal weather srreee. The weather was ton warm b\ this time to
get a realistic ptctme of the s\ stem effectn eriess, so n easut ements w->ie
df. fert'd to the fall.
2.3. PIUSK 3
In November lOP.G, the i adnn < oncenlr'.tion in tin; basement with the fans
operating ianged from r> to li pCi/l., onl\ sounded
200
-------
hollow, and wore in fact filled with sand. Foam was injected above the sand.
The fans were turned off for t»o hours while this was done, and the radon
concentration in the basement rose to 180 pCi/L. When the fans were turned on
again, the concentration continued to rise, reaching a peak of 320 pCi/L about
two hours after the fan restart, and then fell back to 10 pPi/L over a si.\ hour
period. Concentrations then ranged from 5 to 1-1 pCi/L, averaging 7 pCi/L. The
peaks seemed associated with water use in Lhc basement washing machine.
Alptiu Unck detectors were issued in December 198G for final long term
measurements.
3. OTHfc'R MEASl'REMEN'TS
Tl.e general radiation field over the sit*- was 12 uli/li. A summing pool
has under construction, and the field on the e\ca\ated materia1 uns 11 u!?/'1. In
the e\ca\ation itself, the field at the sh.illou end (l.fi ni depth) was 21 uR/li.
•\ laver of rocks was exposed in the deep end, with "on contact" leadings of 23
to 3f> iiK/Ii. The soil at the bottom of the deep end (2.5 m depth) rr-Tc'
14 iiR/I', eompmabk to the excavated materia!, but one large rock on the
bottom read 42 uR/h on contact. The field inside the house ranged between 7
to 10 uR/h, a\ er-ignig 0 uR/h.
The a\erage radon conn;i '.V.ion measured by alpha-track deteetors ;nci
the period December 198G to Nlarch 1987 \-as 11.G pCi/L in the basenert, and
14.r> pCi/L m the liviiig area.
207
-------
>3-LASl TiiMKNTS Sl>N.\KY FOK HOUSE 0
PMjON AU-5 JKXK1A MO\nvWlNC.
F1USH MITIGATION TEST
SYSTFM 1\\T£
1 ball* french
drain
\entilation two
50 l./s
centra fvi£nl fans.
STYIVS milNG liALXJN (pCi/I.)
TKST
0S/S5 Fsuw oi\
Sl/i-5 Kaus on
0^ "StS K.-u*s on
RVNGE MEAN
2-479
2- 7
6- 10
3- 32
As abo\
Wall4-
dra i ii
\entilainMi t.\»o
100 l./s
centrifugal f;uts
As abo\e ». i t it P.uis o*i blot. 6--133
fans revei->ed to Fans or. blow G- 10
bio,.
Fhur on blow 2- 64
173
5
20
10
123
8
20
COMMENTS
ov ei IG lirs
f e 11 to:
7 hr
equilibrium
over 47 hts>.
over 4 davs
over 1 da\ s
12 hrs at
equil ibr non
over 4 dn> s
Kail * f;-vneh ll.,'S£ Fi\nx or. blow
drain F:\r.s on blow
\ ent i iat i ^n tv.o
150 L/s
ci'iilr-i fans
pre »*suri ring
3- 15
5- 14
o\er 38 hrs
over 38 hrs.
•JOS
-------
SYSTEM MEASUREMENTS FOR HOUSE 9
PHASE MITIGATION.' SYSTEM U\TE
Wall and freneh diain 02/86
\entilat.ion ; t».o
100 L/s centrifugal
fans
SYSTEM MEASUREMENTS
COMMENTS
PRESSURE
FLOW
RADON
ra
(L/s)
(pCi/L)
15
17
650
Riser A -
fireplace wal 1
18
23
Riser U -
fireplace wall
35
53
360
Riser C - rear
at fan
38
2 A
200
Riser D rear
Kal 1
¦13
16
Riser E -end
UJ»] 1
8
Basement air
1
0.5
Baseboard duct
rear wall
3
Baseboard duct
rear u-all
8
4
Baseboard duct
end will 1
1
10
Baseboard duct
end «»all
2
100
Rubeboaxxl duct
front wall
0.2
25
Baseboaixi duct
front tsaJ 1
3
60
R'tseboard duct
front wall
20
-------
20
DRYER
WASHES
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Hy
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pucrr
-Note 8
"PUMP
•PRE4&URE T3V^i<.
-W^-reR. HEA3SR
E 5LA& ON
^•RAPE. *
MOTE6: 1. ret-T iwstaluec? under &fJie-K puwr
THIS AREA
LOW COST REDUCTION OF 8NDOOPI RADON
HOUSE
NUMBER
BS
FOUNDATION PLAN
Data: AU6-. '&(,
s
IWQIIWi
Mitigation system: ^u^l^SLAB R^eS^URiZfiXKti
PHASE: 1
210
-------
&L.CX-K J
WALL «
£i"<& FVC. Sfc^TtHL.
1 BCAM
METAL ,
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DRYER
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CVER PASS.
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PUMP
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PSE-SSUfPE TAMu
watsk
HEATER
S^Uo'
LOW COST REDUCTION OF CMDOOR RADON
FOUNDATION PLAN
MHIpatlon system:
Dote: ?//£*
PHASE* 2 AWD
P«A5fc.p.|MAy
HOUSE
NUMBER
s
211
-------
HOUSE 10
PENNSYLVANIA PER MLWSLKEMEN'TS
Korking Lc\el grab samples (Kusnet/.)
Heating season short term a\eiagc KL (Rl'lSL')
Heating season average radon (Terrndev.)
Rudon concentration in \»ater
C26 pCi/L
35 200 pCi/L
1.260 KL
1.08S KL
1. DESCRIPTION
'This one-storv liouso \%ilh attached double garage was built in tlie mid
1970's on a sloping site at the lop of a ridge in u i ural subdivision to the
of Bti.VLi lo\>. n. The fioAt val! is of brick, the other ualh. are of siding. The
walkout basement is built of hollov conciete blocks.
(
There is a concrete block chimney structure in the basement I hat passes
through the floor slab and contains a basement fireplace. The basement i.alls
an; in good condition, uilh no significant ci aching, and are topped x ith a full
\%tdlh sill plate. The poured concrete floor slab is m good condition, \*ith no
significant floo: clacking, and a sr.all wa'l/floor joint. There aie openings
nroui.d rougl.i'i! -.i. pijir.bing sei \ let,-.-;, and around a toilet in the basement.
Healing is b> ho1, water !s iso'.'oai d toiv.ectors heated by an oil and coal fired
boil'.!'. Tin- Loili-i stands on t pad sepal-ale ftom the floor slab.
T!ie oviiier sl.ited that lht pei under drain s.\ stem (t.eepnig lilt-) v as bedded
in ci us lied stone, end went completely aiound ! he outside of the house -
including the g irage \wd!. ! tic garage f'uoi dram is connected to tlie tile.
2. ACT 10\
\s this house \>as ^'ie of the few uith a permit ter dram, tlie mitigation
niL.'isine chosen fi.n dc iwinsirat ion 'i' tins site was \ enlilatioti of thi j imeler
d l i n :.
I tif (jeri'-.elei fltain discharge pipe a.as found at a low point of the site,
and the lin.' '••need hack to th" house. An ation m \de at tlie estni.ited
junction pom"., mid It..1 junction *%it!: th< tile v..'s uneowMod. l'he depth of soil
>t tins point c>i11\ em, iMSiiffu .out U> pr«.'\ ent f: ee^iinj of a ".ter 11 <3p.
'! ! i di.nn vn.is theiefoii • 'i.n\i'iid f.u J. Z in along I ho rear of II"- 'icusf till
2.1.
ph\si: i
-------
60 cm of coic: was available. At thai point, a water trap was connected to the
drain line and un extension run frorj the trap to join up with the original
discharge line.
The downstream side of the trap uas extended vertical!? for uri mspc< tioii
riser, and cupped off. The other side of the trap was. extended vertic.illv for a
fan riser. A flexible duct was provided to n centrifug.il fa" housed in a wixiden
box. A temporal > electrical hook-up wus made to an outdoor outlet. The
garage floor drain was closed L\ placing p piece of rubber kicked carpet over j».
In August 1985, the uidon concentration in the basement fell from 14 pCi/1
to G pCi/L when the fan uas turned on.
2.2. PHASE 2
The soil gas wit)idi.»wn bv the fan is saturated with wat^i v apour at the
soil temperature. This uas no problem in the warm summer rionths, but in the
fall the vapour condensed, and filled the flexible hose with water, ~utt.ug off
the airflow to the fan. Befoi->' an> winter measurements were made, the
centtifugal fan was removed from the protective box, and mounted direct)", on
top of the vertical plastic riser. (\inde.;satr»n would run do*, n the t iser,ind not
block the fan. The auction in the weeping tile was increased from 25 to 70 Pa.
In November 1985, following the fan change, the radon concentration tn De-
basement ranged from 0 to 6 pCi/h, avei aging 1 pCi/1..
Alpha track detectoi s were issued in December 198." to check on the long
term performance of the svslem.
In February 198G, the mdnn concentration in the basement langed f i < jiii 1
to 20 pCi/L, averaging 4 pCi/L. The higher readings were associated with use of
the washing machine, so at least part of the ration was supplied by the w:tte:.
In May 1986, the temporary centrifugal fan v«as replaced by a per'ii.inent
plastic bodied in-line centrifugal f.m. This nn'i eased the suction to 20 Pa, tit .¦
flow of 78 L/s, with a radon < onccnti ultou m 'lie dischaigod ,nr of 1 200 pCi/'L.
2.3. PHASI- 'A
In N'o\ ember the ilectiical • oniieot ions? to (lie fan w cm e lr i' I - "
pei iruinerit. The radon conicntinlinn in '-lie basement tanged ft -i:t 1 to 18 p- i/L.
averaging 7 pCi/1.. I In. higher < oncentrations weie associated with us" t,f t' i . ¦
washing machine.
\lpha liai.lt deteetois w cm e issued in December foi find Ion* t- i .i
rreasui einents.
21 3
-------
Tin- fan performance was. checked in January 1987. The suction »«as sliil
200 Pa, and the indon concenti ution in the dis-chatged air \>as 2 100 pCi/L.
3. OrilLR ME-\SURl-Mi;NTS
The radiation field in side and nround the hout>i_- rnnyed fiom 9 to J 1 uR/li
in the bnsemoni, a\ ci ugmg JO uK/h. Tin.- field u\ or the iclati\elj luidisliu bed
front lawn ranged fiom If) to 20 uR/h, and at the roar of the site uheie the
spoil from the basement excavation !iad been di&ti lbutrd, tanged fiom 20 to
3f> uR/h. The o\etall outdoor aveiage vas 20 uR/h.
The a\eiage radon concenti dtion o\ei the ;jenod Decembci tOSfj-March !08G
as measui cd b\ Alpha Tiuch detectors* uas 3.C> pCi/L upslauh, and 5.3 pCt/L :n
the basement.
The ai ertigo ludon concentration ineasuicd b> alpha-track detecLois u*ei
the period December 198f> to Match 1087 \.a
-------
MEASUREMENTS SUMMARY FOR HOUSE 10
PYLON AB-5 HOURLY MONITORING
PHASE
MITIGATION
SYSTEM
1 Weeping tile
ventilation
50 L/s
centrifugal
TEST
DATE
STATUS DURING RADON (pCi/L)
TEST RANGE MEAN
08/85 Fan on
5-307 87
COMMENTS
over 36 hrs
fell to
equilibrium
of 6 pCi/L
2
•\s above
11/85
Fan
on
2-
1
3
over
5 days
Fan remounted
J1/85
Fan
on
0
6
1
over
4 da>^
As above
02/86
Fan
on
1-
20
4
over
4 days
3
Weeping tile
11/86
Fan
on
1-
18
7
over
4 days
ventilation
150 L/s
SYSTEM MEASURfcMENTS FOR HOUSE 10
ni-VSL MITIGATION! SYSTEM D\TE SYSTEM ME.VSUREMENTS
PKESSUiF FLOW RADON'
(L/s) (pCi/L)
Wf-epinr; till! 11/85
ventilation 50 L/s
ctfi.t t i filial
As aV>o\e 12/85
Weeping tile 05/86
ventilation ISO L/s
rlfuga!
I'a
25
70
85
200
30
53
45
78
2 800
0.4
1 200
COMMENTS
Temporary fan
in box
Direct mounted
fan
Fan riser
Outdooi air
Fan riser
As abo\«»
01/87
200
2 100
21."
-------
<£>M G-SSA.rsS.
MOL-L£?W
C-&HC. SLOC.K.
F=VPUNJtW"nCM WALL
TYP
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AT TOP* TH\^» VVAU-
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WELLTAUkl
ow 3LA&
EXl-STIWer \AyELEP>lN i
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KAr^AL FjJ^-CT K6
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<2»-S.EC5)
OPEW 6ELL-i AT
Tt?P* THl^WALL
LOW
COST REDUCTION OF INDOOR RADON
HOUSE
NUMBER
fJliill
FOUNDATION PLAN
Dato: MP/.&&
10
UfM
Mitigation
syatom: WEEPimCtTilE -^dUc-TIOM
PHASE: F/WAL
216
-------
HOUSE 11
PFN\'S\ LVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Heating season a\erago radon (Terradex)
Radon concentration in hater
0.7-18 WL
-19 pCi/L
low (municipal hater)
1. DESCRIPTION
This two-story end roh-house was buiJt in the mid 1970's near the top of a
small hilt in Bo>erlohn. All thiee outer house halls have the lower half of
brick \eneer, and the upper half of aluminum siding. The top of the basement
halls is co\ ercd by the sill plate, which has been caulked lo the blocks by the
o\>ner. The halls ha\c been painted with sealer paint, and there are no hull
cracks visible.
The basement flooi is a floating slab uith an open perimeter drain (french
dram) agtimst the three outside \>alls drained b> an open pipe just visible at
the front edge of the slab. The slab whs tight against the pai t> hall. These
are no significant cracks in the slab, oril.\ surface craving, and ser\ ices
jienelrate the slab in one position. Heating is by electrical baseboard units
upstairs onl> .
As the e\terior halls m this house were parliall.N closed at the lop, and
there has .in open drain around the perimeter of the floor, Ihe mitigation
measure selected foi demonstration in this house was ventilation of the holloh
block ual!s und the French djain.
Holes here d tilled in each block i avilj of the esLerioi halls appi o\imatel j
~i to 8 >r drill holes I'luounVercri mortar in 1)10 ities.
A commi-K nl Channel Dnnri, (n rectangular plastic es.li usion intended to en Hue I
hater leaking through block walls) has si iThO'J lo the halls and floor to cove1
the diain and the holes di illed in the conci i;te blocks. Asphalt cement h.is us<-d
as caulk. The plastic shape has \ oi j rigid in
-------
amounts of caulk were needed to fill the gaps between the uneven floor and the
edge of the shape.
Ihe plastic channel was only 8 cm high and 6 cm wide, so the usual "4
inch" pipe could not he attached. Instead, two "3 inch" pipes were ultached, and
joined to a "4 inch" riser. A flexible duct was run from the piping, through a
piece of plywood placed in the rear basement window, to a small centrifugal fan
mounted in a box and placed in the window well.
N'» work was carried out on the pal' v wall. The reason for tins was that
cooperation from the neighbor would be reqvured to reduce the op«-n area of the
wall, and they had not expressed any interest in the program.
In August 1985, the ladon concentration in the basement was 90 pCi/L.
When the fan was turned on radon levels fell to approximately 1 pCi/L.
2.2 PHASE 2
In Januarj 1986, concentrations ranged from 15 to 30 pCi/L, averaging
20 pCi/L with the fan running. No measurements were made with the fan off,
as the occupants were concerned that higher levels might result.
Investigation found that the fan was drawing 35 L/s from the system, which
came mainly from the rear and side walls. The air in the duct along the front
and side wall cnme ftom abo\e grade (<4 pCi/L radon). The an- going to the
far had 75 pCi/L, which must all have come out of the rear wall section. Smoke
tests showed that airflow was definitely into these walls, preventing them from
being a route of tadon critrj. Smoke tests shewed that air was moving out of
the party wall, wiih radon concentrations measured between 40 to 1G0 pCi/L
depending on location.
This suggested that the party wall uas> the major remaining route of entry.
Further worlt would include \i'iitilation of the party wall. How«;\er theie were
large open mens at the top of the wall, and increasing the airtightness would
bp difficult. Access from both sides would be needed uiv', 'he neighbors had
not expi estied a'l MiSe.'eol in participating in the progiuin.
The ownei was not inteiested in continuing in Lhe experimental pi<>gram,
and said that In* would get a 11K\ to sol\e the problem. No further woik was
earned nut in tins house.
Alpha track detectors weie issued to the owner in Juniurt 1987, but weie
not ieturned.
218
-------
3. OTHER MEASUREMENTS
The radiation field in the house ranged fiom 6 to 9 uR/h, averaging
8 uR/h, and the surface radiation field on the site ranged from 7 to 10 uR/h,
averaging 9 uR/h. Deeper soil uas exposed in a road cut at the top of the lull,
and the radiation field at a depth of 1 m was 13 to 16 uR/h.
MEASURFMENTS SUMMARY FOR HOUSE 11
PYIjON' AB-5 HOURLY MONITORING
PHASE
MITIGATION
TEST
STATUS DURING
RADON-
EASURE>IENTS PCtt
HOUSE
11
PHASE
MITIGATION' SYSTEM
DATE SYSTEM MEASUREMENTS
COMMENTS
FRESSUR1"
FLOW
RADON
l^a
(l/s> (pCi/L)
2
Wall ar«J Tiench
drai a
03/8G 50
35
75
Fan duct
ventilation 50
i./s
13
17
1
End vuJ1 duct
centrifugal fan
2
2
Front uall
du>_L
160
Be.un pocket
60
Between l^-ams
•10
Wall cavit.\
14
Rasfmunt air
219
-------
iq'-o"
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WATER SUPPLY
^SS-WELR.
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&L<^>AFZ.t> TYPE.
Mitigation system: wall/ouAB ^>lI£-TI<^kJ
PHASE:FiMAL
1 1
220
-------
HOUSE 12
PENNSYLVANIA DER MEASUREMENTS
Working Level grub samples (Kusnetz)
Heating season short term aveiage KL (RI'ISU)
Heating season average ridon (Terradex)
Radon concentration in water
0.220 Wl
0.033 WL
6 pCi/L
4 300 pCi/L
1. DESCRIPTION
This rural single storj dwelling it. built on a sloping site on the side of a
hill some miles to the wosl of Boyertown. The hause walls are covered with
sidi-ig, and the unfinished walk-out basement hfs concrete block walls. Some
light floor cracking is \ lsible, and there is a sleeved oil line entry through the
basement wall. Heating is bj forced air, and there is a fireplace on the main
floor.
There is an external peilmeter drainage (weeping tile) system, which
discharges to a low point on the site. The owner had installed it himself; and
said that it ran round all four walls at the junction of the footing and wall, a>ri
was covered with 30 cm of ciushed sione.
2. \CTI0M
2.1. PHASE 1
As this house was cne of the few with a weeping tile sjsteni, the
mitigative action selected for demonstration at this huubC was to exhaust the
keeping tile.
A water trap was installed on the discharge pipe, .1 riser pipe was placed
on the house side of Die tiap with an axial fan installed in the open end of a
6/4 inch sewer pipe leducer. An inspection riser vas provided on the other side
of the trap so that water lesels * ould be checked.
The ti np could not be installed close te the house as '.he ground vas loo
ificlij, and so it \.as plai.ed nbout 2 in fiom the house. The fan ijs^i pipe i>os
run under grou ud back to the side of the house. The ground cos ei in tins area
wis onlj 30 en1, so thei e was a concei n about I lie trap freezing in the winter
and blocking the drain dining the sp> ing moll. H was ngieed a% i I li the ownei
221
-------
that insulation and extra giound cover would be provided if the installation was
successful.
In Jul} 1985, when the perimeter dram ventilation fun was turned on, the
«\?rnge radon concentration fell from 11 pCi/L to less than 1 pCi/L within one
das .
2.2. PHASE 2
In November 1985, \\ith the fan operating, the average radon concentration
was 4 pCi/L, but lose to 32 pCi/L v.hen the open fireplace on the upper floor
was lit. To improve \> inter perfot mance, the a\i:il fan was replaced by a higher
suction centrifugal fan mounted directly on t!ie riser. Flows and suction were
increased fioin 27 l/s, 50 l'a to -12 L/s, 110 l'a.
In January 1986, with the new fan operating, the a\ erag^ radon
concentration ni the basement was less than 2 pCi/L, with a brief peak to
9 pCi/L when the fireplace was lit.
Alpha Track monitors were installed in .lammry 198G, but could not be
found in March 1980.
During the summer when the windows were open, the owner was disturbed
at night by the noise of the =ir discharged from fan. He dug a Ijerich to run
the fan riser pipe away from the house to the edge of the lawn, some 13 m
distant from the house, installed an outdoor electrical outlet at that location to
provide power to the far, and reconnected the fan.
2.3. PHASF 3
The fan, mounting, and electrical hookup were not suitable for a permanent
installation. In 'November 198S, the fan was replaced b,\ a plastic body in-line
centrifugal fan. The suction increased to 210 Pa at a flow of 63 L/s, with a
radon concentration m the dischaiged air of 190 pCi/L.
In December 198(1, the radon concentration in the basement ranged from 2
to -1 i'Ci/!., a\cm aging 'i pCi/L. These results were good enough to issue alpha
track detectors fni final iihmsiii •MiUMits.
•}. orhfr v::\si.'nmr\ rs
The radiation field in and around the house langed from 3 to 6 uR/h in the
basement, averaging 5 uR/li. On the site the field ranged fioin 5 to 9 uR/h,
a\ ei aging 7 uR/h.
222
-------
The average radon concentration measured by alpha-track
the period December 198G to March 1987 was 3.0 pCi/L in the
2.5 pCi/l. in the living area.
MEASUREMENTS SUMMARY FOR HOUSE 12
PYLON" .Ml-5 HOURLY MONITORING
detectors over
basement, and
PHASE MITIGATION
SYSTEM
1 Drain tile
\entilation
, 50 L/s axial fan
2 Drain tile
\entilation
50 L/s axial fan
TEST
DATE
STATUS DURING RADON (pCi/L)
Drain tile
\enti]ation
50 L/s
centrifugal fan
Drain tile
ventilation
lf>0 L/s
centrifugal fan
TEST
07/85 Fan off
Fan on
11/85 Fan on
01/86 Fan on
12/86 Fan on
RANGE MEAN
4-20
1- 4
2-32
0.5-9
2-4
11
2
COMMENTS
over 24 hr*.
over 18 ha-s
over -16 hrs;
levels
highest when
fire on
over I days;
le\els
highest ndien
fire on
over 63 hrs
SYST1M VIEASURTMENTS IXDIi HOUSE 12
niVSE MITIGATION SYSTEM DA.'E S\STEM MLXSUREMENTS CX^IMENTS
PRI1SSURL F1jC.n RADON
Pa (L/s) (pCi/L)
2 Dram tile 11/85 50 27
ventilation 50 L/s
axial fan
2 Drain tile 11/85 110 42 Fan chaime
ventilation 50 L/s
centiifiig.il f.
m
Dr.im tile 12/80 210 05 190 r.m change
\enli lation 1.10 L/s
een tii fug<\ 1 fan
223
-------
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COST REDUCTION OF INDOOR RADON
HOUSE
wuwpsn
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FOUNDATION PLAN
Dato: 1 c/2G/g&.
1?
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Mitigation
syatom: wegf
-------
HOUSE 13
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Heating season average radon (Terradex)
Radon concentration in water
0.060 U'L
64 pCi/L
12 900 pCi/L
1. DESCRIP'l ION
This single story dwelling uith attached garage was built in the late 1970's
on a steeply sloping site on the side of a ridge m a rural subdiMsion to the
v>est of Roseitohn. The gaiage is attached at the lou end of the house, and
the floor is level v»ith the basement floor. The front wall of the house :s brick,
the others are of siding. Heating is by oil fired hot walci \%ith baseboard
convectoj's upstaii s, supplemented by a wood stove :n the basement.
Part of the basement is out of the ground, and there is an outside door.
The interior vails are unfinished, but are insulated uith beadboarJ sheets. The
concrete floor slab is in gocd condition with no significant cracking. There is a
brick fireplace in the basement.
The ov«ner said that an exterior perimeter drainage pipe (seeping tile) ran
round three sides of the basement and might run along the fiont wall of the
gaiage. The tile dis< harge pipe i>as \ isible at a iouer pai t of th^ site.
As this house had at leust a partial helping tile sj stum, the mitigation
measure chosen foi Honionsti ation at this site uas seeping tile \ entilatiun.
•\ trial e\ca\ iitmn to a depth of l.f. m beside the garage front uall did not
find the tile or leach the footing in that area. The ouner said the foundat>on
\«as eighteen oi nineteen courses of i.oi:ci etc blocks deep there, so if the tile
existed there it i ould be buried up to > in deep and has maei.essible.
The line- of the perimeter dtain discluiige pipe was tia'.ed back to the
house. \ small exra\ation near the back door found the jun< tion ' ith the ti!i
at CO (.in depth. -\ water trap fabiicated from staiidaid 1" li^ht weight plastic
'Tees unci elbows was inserted at this point to pie\ent air being drawn up the
-\C noN
2.1.
PtUSF 1
22 f.
-------
discharge pipe. An inspection riser was pro\ided ut the downstream end of the
trap, so that the water level iri the trup could be checked.
This was not a suitable place to put the fun, so a second excavation to the
tile wis made at the rear corner of the house. A riser of -1" lightweight drain
pipe was Teed onto the pipe. An axial fan was installed in the open end of a
•i/6 inch adaptor joined to the riser by a 180 degree bend. Power was
pro\ ided b> an extension cord from an outside electrical outlet 011 the upper
le\el balcony.
In Julj 1985, the radon concentration in the basement fell from 80 pCi/L to
15 pCi/L when the fan was turned on.
2.2. PIUSL 2
In December 1985, the usial fan gave a suction of 35 Pa at a flow of
20 L/s with a radon concc-ntruLion. in the exhaust uii < f 770 pCi/L. !o impin\e
the performance before the winter season, the axial fail was leplaced by a small
centrifugal fan mounted directly on the riser. This increased the suction to
110 Pa at ti flow of 3G L's. and the radon concentration in the exhaust to
1 3 50 pCi/L.
Tn January 193H, the ladon i. jnccnlraiion in the basement with the rtn i.i
operation ranged f. iir 9 tu 710 pC./L, averaging 20 pCi/L. Alpha track
detet toi t wer< issue;.* in Jtinjut v to l heck on the '.oncer ter i. perfv.i uiance of
the system.
\ irtue powerful fan was '"•! deied, but did not :irri\ e until via:c!:. I'n.
small centrifugal <"an was replaced b> a lai ge plasth bodied m-hne centufugal
fan in Ma> 19PC. This inc.-eased the suction to 250 !'a at 75 L/s, with an
exhaus* coii'.enti ition r,f 850 pCi/L. light da> s later Ihe concentration was
7j0 p'.'i/L, sliint trrui i adon measui emenis were made at this tune as '.hf*
weathe: was waini, aiu! windows wcie open loutinelv.
2.3. :i
Ui \ovi'iuliei ' 9£6 tla' I adon ro,i< imtialion in the basement ranged fioni ^
: i 25 pr l/L, n\ci aging 1! i>Ci/l.. 'lhis indicated th::t i \ i"i 'he ''luhe: snctum fan
w i s not abl t*. the pi "hsnr" diflei enl i,.ls o\ er all the basemen'
s« rfa'.es.
(i '.-'ilil^'n ¦>., and sn it was decided to a subfkxn s> stem Lei e. \ fr>u: po'nt
bj sU ii. us'i'g la' g'- jlasti bodifil in-line centiifugal :an was n, stalled .n
-------
Januarv 1987. basement radon concentrations vwith ju^t the weeping tile b) stem
in operation ranged from I to 19 pCi/L, a\eraging 8 pCi/L, and v»hen I he
subfloor system was turned on as uell, concentrations tanged fr^in 0.1 to
4 pCi/L, averaging 2.1 pCi/L.
Suctions l'lov. s and radon concentrations in the subflooi s\stem pipes \\ith
both fans running uere; garage ualJ 1 10 Pa, 9 L/s, 230 pCi/L; rear uall 1 10 I'y,
26 L/s, 20 pOi/L; end ball (by the fan) 175 Pa, 7 L/ith both fans in operation.
Alpha LracK d<-tectuis i%ere issued in rc'.uiary 1987 to al\e oi. had been duinptri tin field l.Miged fron. 1to 23 i:!Vh 10 ei iged
20 i.i
-------
The average radon concentrations measured with alpha track detectors over
the period December 1985 to N1arch 1986 were 11.-1 pCi/L upstaus, and 17 pCi/L
do\» nstairs.
The average radon concentrations measured \>ith alpha track detectors over
the period Februarj 1987 to April 1987 were 2.3 pCi/L in the basement, and
2.0 pCi/L upstairs in the living area.
MEASUREMENTS Sl^lAm PCJR HOUSE 13
PY1X>\ AB-5 HOI-RLY MOM 1 TORI NO
PHASE MIT1 CATIOS
SYS TO!
1 , Keepi ng t11 <=>
\entilet »oi>
50 L/s a\ial
fan
2 Keeping tile
ventilation
50 L/s axia] fan
TEST
DATE
07/85
STMVS IXTil\(; RADON (pCi/l)
TEST
Fan on
01/85 l-an on
liAN'Gi: MEAN
10-88 35
9-19
22
COMMENTS
over 21 hrs
f al1 to
eqm 1 lbrium
of 13 pCi/l
over 32 hrs
3 Keeping tile 11/86 Fan on 3-25 11 o\er 1 days
ventilation
150 L/r
oentri fvigal ( an
Sub-slnh Keeping 01/87 Keeping tile -1-19 8 over 18 hrs
tile ventilation fan onlj
two 150 L/s Both fans on 0.4-1 2.1 evi r 71 hrs
ctjiitr i fugal
01/87 Both fans on
Keeping tile
fail off
Both fans off
02/87 Sub-slab fun <
1-4 2.5
5-30 15
22-117 91
2-11 5
ovei 2l hrt%
over 24 lu t>
over -18 hrs
over 4 il.ij;*
228
-------
SYSTEM MEASUREMENTS FOR HOUSE 13
PHASE
MITIGATION SYSTEM DATE
Weepirig tile 12/85
\entilntion 50 l./s
axial
Weeping tile
ventilation 50 L/s
centri fiuial
Weeping tile
ventilation
150 L/s centrifugal
Sub-slab + 01/87
weeping tile
ventilation 150 L/s
eeriti lfugal
As abc\e 02/81
SYSTEM MEAS UREMENTS
PRESSURE FLOW RADON
CCM1ENTS
Pa
35
12/85 110
05/86 25-J
140
MO
i 50
175
112
160
190
210
160
160
200
240
125
140
160
200
(L/s)
20
36
75
9
26
7
7
10
30
8
8
11
27
7
t
9
27
7
7
(pCi/L)
770 fan riser
0.3 ambient
(outdoor) air
1 150 riser for net-
fan
860 fan riser
690 fan riser 8
days later
230 Riser A
20 Riser R
1 100 Riser C
2 100 Riser D
A*
B«
C*
D*
A*«
B**
C**
D**
A*
B»
C*
D*
A: Garage wa] 1 .
B: Rear wall.
C: Krxmt wall.
D: Eml ual1.
* SuV>-s]ab fan only.
** Both fans ctri.
229
-------
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LOW COST REDUCTION OF INDOOR RADON
FOUNDATION PLAN
A WEEPiMO TILE AWP
Mitigation system: £,ub-£>la& 6uc.ti
-------
HOUSE 14
PENNSYLVANIA DEH MEASUREMENTS
Working Level grab samples (Kusn<*tz)
Heating season average (RPISU)
Heating season radon average (Terradex)
Radon concentration in water
2 500 pCi/L
0.4 id WL
0.124 WL
36 pCi/L
1. DESCRIPTION
This single storj dwelling was built in the early 1980's on a sloping site on
the top of a ridge some miles vest of Boyertown. Half of the front house wall
is brick \erieer, tho ntiier walls are siding. Heating is b\ electiic baseboard
heaters upstairs only.
The walkout basement has connote block walls, rind the sill plate does not
co\er the open block voids. The concrete slab is poured U> the walls and forms
a tight joint but for a feu slight perimeter cracks. The slab is penetrated by
steel columns which stand upon thesr own footings, and two ci-icks which extend
about half the width of the slab. There ate two openings through the s'^b at
samtar\ drain stacks, where the concrete does not fill the space between the
rear of the stack arid the basement wall.
A pel imeter drainage (weepir.g tile! s\ stein is installed along the two uphill
sides of the house. Plastic sheet was also applied to the extendi of these
walls during construction for waterproofing.
2. ACTION
2.1. phasi: 1
As this house was one of the few with weeping tile, the mitigati\e action
chosen fur demonsii at ion at this site was to exhaust the pelimeter diainage
system.
The discharge pipe was unro\ered and j watt-i trap inserted at Ihe junction
with the drain tile. \n inspection riser was pro\ ided at the downstream end of
the ti a p. \ fan risei was installed on the house side of the ti ap and an a\ial
fan was inserted in the open end of .t C/4 inch adaptor joined to the risei b> a
23 i
-------
ISO0 bend. Temporary power to the fan was provided from an electrical
adaptor inserted in an exterior light fixture.
In July 1985, the concentration in the busement fell from GO pCi/L to
9 pCi/L when the fan was turned on.
2.2. PHASE 2
In November 1985, the concentration ranged from 6 to 23 pCi/L, averaging
15 pCi/L with the fan running continually. As the system was not effective,
replacing the axial fan with a higher suction fun was considered, but rejected
as the tile did not go round the house, and increased suction had been
ineffective at other locations where the tile was not continuous. It was
decided lo install a wall \ entilation system, as thcv had been successful in
Phase t.
The top of the basement wall was readily accessible, except for the section
wh 1936, the radon foiu'L-ntration in the basement with (hi- vail
v. entiLitiun fan i tinning longf.d between 0.4 to 2 pOi/L. The air flows wei"
float wall 19 l./s and 15 I/s; end wall 17 L/s; rear wall 18 L/s, ar.d far: end
wall ? 1 l./s. The radon concentrations in the ai^ flowing from the walls wis
front wall 1 pCi/l. and 7 pCi/i., end wall 3 pCi/I., bat k wa!! 6 pCi/L, anil fan
end will If) pCi/L. \ smoke test showe .hat the airflow was into the walls from
the house.
The low radon Liviccnti 'iMons indicated that much of ihe air was diawn
froi'i the house. The w,i!l
-------
Subsequently the owner added a small sunroom extension to the rear of the
house. Although concrete blocks were used for the foundation, the concrete
slab was poured on top of and into the blocks so that there kas no direct path
for soil gas to enter the structure. The only entry route was the joint between
the slab and the wall, and that area was likely to be well \entilated b\ air
leaking into the wall. A vent pipe was included in the subfloor fill, but was not
connected.
Alpha Track detectors were issued in February to check the s>stem
performance, and the effect of the sunroom extension. Radon concentrations
were low, so the precautionary measures were effective.
2.3. PHASE 3
Tin- sj stem was checked and found to be opei.Uing normally. A.lph& Truck
detectors were issued in December 1980 for a winter tune measurement of
average radon concentration.
3. OTHER NEASL'REGENTS
The radiation field inside the house ranged between 6 to 10 uR/h, a".
8 uR/h, and over the site ranged from 5 uR/h on the crushed stone driven-»\ to
12 uR/h, averaging 10 uR/li.
The average radon concentration measured by Alpha Track dele.tors •>m>i
the period February 1983 to April l'JS5 was O.G pCi/L i-i the basemen', and
0.6 pCi/L upstairs.
The average radon concentration measured b,> alpha-track detectors over
the period December 198G to March 1987 was 0.5 pCi/L in the basement, and
0.7 pOi/L in the living ot^a.
231
-------
MEASUREMENTS SUMMARY FOR HOUSE 14
PYLON' AB-5 HOURLY MONITORING
PHASE MITIGATION TEST STATUS DUUNG RArXA (jCi/l ) COMMENTS
SYSTEM DATF TEST RANGE MEAN
1 Drain tile 07/85 Fan ol'f 10-67 47 o\er 24 hrs
vontilation tan on 14-58 28 o\er 22 hrs
50 L/s axial still falling
2 07/85 Pari on 6-23 15 over 10 lira
2 ball \entllntion 01/86 tan nn 0.4-2 1 o\er 4 days
100 L/s
centri fusfal
s\stum measi ri'mlnts for nasr m
11 IAS! J
MITIGNTION SYSTEM DATE
SYST1M MkVSrRI^lENTS
PliESSlKE FU)W RADON
Pa
COMMENTS
(L/s) (pCi/L)
Dr.iin tile
\en!ilation 50 L/s
11 /85
38
17
Fan ri ser
V»al1 venti 1 it inn
100 L/s centrifugal
01/P6
33
25
20
13
11
13
34
64
19
15
17
18
15
1
3
6
1
1
0
F;tn ua 11 i > ser
Main duel r^ui
Front uall
Front joti u.ill
1 j«l ^al 1
Hear uall
Room hir
Drn in
Seizor
penetration
23 1
-------
• -
PiJMED WAUL:
K/iouwrEP
260CFMFAM
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V
>T
0
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\J
r<3
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£j 2T6-I
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/ BL'TK ^5-U.
BEAM FtaiKET
F1LUEO WfTH
ffc'L.t'U f^ETHAN E
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,4*4" Pv:-- :Kp&
BLOCK ^EiJ_
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FR<9MT
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v»
w
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WALL TflPCE,
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I
6TFCI- QSAM
LOW COST REDUCTION OF INDOOR
RADON
HOUSE
MUM3Ef*
BS
FOUNDATION PLAN
Date: y/'.yez
If
*««»•
Mitigation system: wall. -fsUC-TiOM
PHASE: 2
235
-------
ilOVSL 15
FENNSY1\ \N1 -\ PEN Ml-ASl'rtFMENTS
\\orkuig l.e\p) gi ab samples ihusnet/) 0.171 KL
Sha.H term average VI, <1?P!SL") 0.019 KL
Radon concent ration iri \»ater 4 900 pCi/L
1. DFSCRIPTION
This two-stoi y hiinso-wjl h attached garage i>as built in the earlj 1980's on
a faulv lev i*l si to near the lop of a hill se\eial miles southwest of Boyertov. t:.
The lunisf \»alls are of bidmi;. rho p u tly finished basement is deepei than usual
! has holloa com i ete bloc 1\ halls 2.5 m (8 foot) high, and no basement
vindo^s. The ^alls lin\e solid cap blocks. Thci e are no \ lsible cracks m the
Viiil'.s and the vatet sei \ ict; entry hole has been mortared closed. The conciete
floor slab h !S no construct ion joints and shous no cracks. The peinr.etor
^a*!/fK'or shi :u!.nuo i.iack is small. Heating is l>\ forced .nr \% ith an o;l/v»ood
fired furnace.
flu' o\>ner said that the walls \.eie reinforced internally evei y 2.5 :u (S
feet) around the hou^o b\ steel reinforcing burs and concrete pouted i-itc the
blocks. (1 ho builder uswall\ did irsdusti tal construction.). lie also said th.it
ueepMic tile perimetei d:-i:.i surrounded the entne house, including t lie
hou.-»<•/gai 'Igr- vail.
C. \CTI0V
2.1. PHNS1 1
As this house u.is one of the f^u \»ith a complete im .-ping tile s;, stem, l ho
mitigation method chosen for demonstration at this site was ueeping t:le
\ mutilation.
Tls" disthaige pip'" friMn the tile \*.is found at a Sou point on the site. 1 ho
; :pe was c\i i\ nted ibout 3 f< <'t f'om the open end, and .1 water trap w:'.L
,*? ion i isri h»s installed.
r'u> niv nor oMgi . i!l> had the tain-u itei leaders <_oniie<_ted to the pel !l.,o,..e;•
.,:•!. This lid to wt t walls at tnu'-s of heae^ t.ain, so h" h.-»d nut in a
rfai.e s\.sti in jus! to <-ol!ei t i am u.iter anil lead it nu i\ from the hou.-e.
T! •' eoaiieetioijp to th> pel ir-t tor dram had boon iut off just below mound
* <'1 iad i"i ppod.
2'«"
-------
One of these capped risers was located, excavated, and extended abo\ e
ground with 4-iuch plastic piping. A centrifugal fan in a bos with a
child-proof discharge" has connected to this pipe with n f{e.\ible duct. The fun
gave 2" Pa suction at 35 L/s.
In July 1985, the radon concentration in the basement varied between 5 to
49 pCi/I., averaging 18 pCi/L, when the fan was turned on the average radon
concentration fell to 3 pCi/l..
2.2. PHASE 2
The pei formance of the weeping tile ventilation systems was compromised in
cooler weather by condensation in the flexible hose reducing the air flow to the
fan. In November 1P85, the centrifugal fan was remounted directly on the riser
so that condensation would drain back into the piping and not affect the fan.
The suction "was uici eased to 63 Pa, ".ad a;i flow in the system lo 52 L/s. In
December 1985, the radon concentration in the basement with the new fan on
ranged from 3 to 6 pCi/L., averaging 4 pCi/L. Those results were good enough
for alpha truck detectors to he issued.
In May 1986, the fan was le placed bj a permanent plastic bod> in-line
centrifugal fan. '1 he fan ga\ e 175 Pa suction, 92 L/s flow. The radon
concenti ation in the discharge ,tit was 150 pCi/L. Further monitoring of radon
concent i at ions was left till the letum of cold weather.
2.3. PH-\SE 3
The electrical hookup of the fan was not satisfactory for a perc:ar.ent
installation, and in \o\enber 1980 it was replaced by a pWEianenl. electrical
connection.
Aflei the new connection, the radon concent ration in the basement ranged
between 0.? to T.8 pCi/I , averaging I pCi/L. These results were good enough
for alpha I I ack de!oeti>i s to be issued for fincil measurements.
.1. OTI1I-R RTN'A 1 S
The ladiation '*ieli( in and around the house ranged fs.«i". 4 lo 10 wK/h,
a\ ei aging C> u|{/h, in (he basement; ami from % lo 12 uR/h, averaging 10 rK/'i,
on the site.
Iraclt !Uh del "i toi s weie plaet-d in the house in l^ece'tibor a.ul
remn\ ed in Mas i h 19K0. The- nv ei" hi- radon concentration r this |)l' ic,! >.;>s
3.ft pCi/l in the basement and 2."» ,>( i/1. upstan s :n the h\ i.is; :s:ea.
-------
Track Etch detectors were placed in the house in December 1986: and
removed in March 1987. The average radon concentration over this period \»ui>
1.1 pCi/L in the basement and 1.0 pCi/L upstairs in the living area.
MEASUREMENTS SUMMARY FOR HOI'S E 15
PYLON" AB-5 HOCRLY MONITORING
PHASE MITIGATION'
SYSTEM
1 keeping tile
ventilation
50 L/a
centrifugal fan
2 As above
3 Keeping tile
\entilation
150 L/s
centrifugal fan
TEST
D\TL
ST-YR'S DURING RADON' ( i/I )
TEST
07/85 Fan off
Fan on
12/85 Fan on
11 /8G F:in on
RANGE MLAN'
5-19
2-2-1
3-C
0.2-3.8
18
G
3
COMMENTS
over 52 his
over 38 lits
12 hr «qiulb.
over G6 lus
over 4 dajs
SYSTEM MEASl REMENTS FOR HOUSE 13
PHASE
MITIGATION' SYSTEM DVTE
SYSTEM MEASUREMENTS
PRESSURE FIjOW RADON
cwents
< L/s>) (pCi/L)
Keeping ti 1p
ventilation 50 l./s
cen tn f i i:.
Direct mounted
fan
Ueeping tlie
ventilation 150 L/s
centrifugal fan
05/86
175
238
92
150
Fan riser
At fan
2J8
-------
r^A.gA.(VE
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V/ATEK*TAkUC-0
PUMP-S
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BEAM
MOLUAV
l5t_OC-kl
RPUMD^CnoU WALL
v^/top <^5-ut»e:
4-WA5HEI?
E—TLIS
EXI-6TIM6-
W&E.F-IN46- Tl LE
TTR
pipe:-—
^LUMU
TYR
Ffc?R££:T> AIR
F=UR.MAC.E.
N
>HOOZ> PRAME
WAUL. |—
I /-KAkJALFLAKT K6
| / fftW S'EETiiAUy
J/gC tvl<^UuTEC> CM
i^r Top e>F£R
LOW COST REDUCTION OF INDOOR RADON
HOUSE
NUMBER
fflX
FOUNDATION PLAN
Data; wev. '&l>
1?
m
If
Mitigation system: WEEPiNJS. TILESUCJTiOM
PHASErFlMAL
239
-------
HOUSE 16
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Heating season short term a\erage WL (RP1SU)
Heating season a\erage radon (Terradex)
Radon concentration in \»ater
0.63 WL
0.21 KL
395 pCi/L
28 000 pCi/L
1. DESCRIPTION
This t*»o-stor> house with attuclicd double garage was built in the mid
1970's on a level site at the top of a ridge near Bcyertovrn. The front wall is
of brick, the other \»ulls are of siding. The house has a rear family room
extension. The room directlj behind the garage is above a paved cra\» lspace.
The basement is unfinished, with hollow concrete block v.alls and the lop
course of the walls is largelj coveted by a full sill plate. One \»nil is
penetrated by oil lines mortarpj in place. There are no major cracks in the
vails. There is Hii external entrance into the basement, and a small pa\ed
crawlspace is attached to the basement. The crawlspace walls are closed cap
blocks.
The poured concrete floor slab lias no cracks, and is penetrated by steel
support jacks and a floor dram.
The ouner slated that there uas ti perimeter drain (weeping tile) s\t>letn
around tho hou^c.
2. ACTION
As this house uns one of the few with a keeping tile, the imtigatue action
chosen for demonstration at this site was seeping tile \ entilatiun.
The end <.>f the discharge pipe from the keeping tile uas located at a !ou
purl of th<> s'le, and ti ;i< ed bat k to the intertei. lion v. itli the lions- . \n
e\. a\nluin ippr'»% ima'el> 2.5 m deep \*as required to reach the til-1.
Vorttiriatelv the intersection of the diam Inn- and Keeping 11lr» u In re
eslan ited, su onl.s a reksi i <. f¦ 1 > small hole uas needed.
1 he <1im hai £e pipe contiriii'id under the Touting to beneath the basement
2.1.
P!!-\Si: 1
2-10
-------
floor, and the weeping tile was Teed into the pipe. The tile did not continue
beyond this point, and probably does not mnke a complete loop round nil walls.
A "U" water trap fabricated from lightweight plastic drain pipe and elbows
was installed in the discharge line. The trap was extended vertically to the
surface on the house side of the trap for a fan riser, and also extended on the
other side of the trap for an inspection riser.
A flexible duct joined the fan riser to a centrifugal fan installed in a bo\
with a child-proof discharge.
In August 1985, the radon concentration in the basement ranged from 230
to 320 pCi/L. When the fan was turned in the concentration ft-ll to 3 to
fi pCi/L. 2.2. PHASE 2
In November 1985, cooler weather caused condeniauun of soil moisture in
the flexible duct, blocking it coinp'eicl.y. When the hose was emptied of water,
the melon concenti ations in the basement initially ranged from 32 to 73 pCi/L,
and then rose to 106 to 250 pCi/L as the Juct filled with watei.
To stop condensation blocking the duct, the fan was remounted diioctl> on
top of the* riser. Condensed moisture would drain back down to thf 'lie. The
suction increased only slight lv from 105 to 110 Pa.
In November 1985, the concentration with the lemounted fan running ranged
between 120 to 220 pCi/L, falling to 80 pCi/l. after steady rain at the end of
the measurement peiiod.
Alpha Tratk detectors were exposed m the house foi .Januarv 19SC>. The
weeping tile fan was in operation. Average radon concentrations weie 78 pCi/L
in the basement, arid 22 pCi/I. on the main floor and bedrooms. The owners
agreed to participate in a field evaluation trial of Heat Recovery Ventilate! s for
radon control sponsored by a manufactui < r of IIRV's, and one was installed in
earl.v Januarv .
Thv. performance of the weeping tile system could not be eusilv implied,
so alternate mitigation methods were considoied.
As the lops of tin- walls were coveted b> the sill plate, the "itigar.ou
method chosen for demonstration isjs wall ventilation.
In JainiHL\ 1986, the joint between the sill plale ant! the top of llie \ .'lis
was i nulked with asphalt cement. A 10 cm diametei hole was cut appi o\i'i .itelj
in the middle of eai ti wall and TO cm fiom the ftooi . In Hie crawl space the
holes were 15 cm fiom the floor. A "I in< h" lightw eig^l plastic pipe was
2-11
-------
inserted into each hole, and all pipes were joined to a "t inch" central duct
connected to a large wall-mounted centrifugal fan which diew 52 L/s at 62 Pa.
Following this work, radon concentrations in the basement ranged from 3 to
53 pCi/L, averaging 12 pc.'i/L. The HWV was opei ated intermittentl.v during the
period, but corn entrations were so vai lable that it was difficult to estimate the
reduction caused b> HRV operation. It did no more than huh c the basement
concentrations whiie deliveiing 75 L/s of air.
Investigatiori found that an flows were generally into the ventilated
bnsciii^nt vail3, but tio» positive!;. :r.tc ?h^ crnwl space walls. One section of
basement wall between a corner and tht- exterior entrance door was unventilated,
and air flowed from the Weill into the house. Concentrations of 1 000 pCi/L
were found in the front wall, but the concentrations in the end walls were onl>
150 pC)/L, and the concentration in the rear wall was 1 pCi/L. The air drawn
from the crawlspace walls only had 5 pCi/L, suggesting that it was house air,
no' soil gas that was being collected.
The floor slab in the crav 1 sp-»ce was roughly finished, and there was a
\ isible gap against the crawlspace walls. There was u small hole in a corner of
the crawl space floor slab with a marked airflow from the soil to the house at
a concentration of 380 pCi/1..
The system was modified to raise the suctio.i in tin walls. The csntial
duct was •-•hanged from "-1 inch" to "C liu-h" pipe, a second "4 nch" pipe was tun
into the front wall, and a "3 inch" pipe was run to the isolated suction of the
rear wall that had not been ventilated previously. This placed all the walls
positively under suction. The fan now drew 66 L/s .-it 80 Pa.
In Janudi y 198R, following this work, the radon concentration i.i the
basement fell slowlv from an average of 15 pCi/L to 5 pCi/L with the fan
turned mi. The concentration was variable, with spikes up to 16 pCi/I , not all
of which were associated with water use m the washing machine.
The opeamg in the ciawl space fh«jr slab was filled with nsph'tlt cement in
rebruai v 1986. following this, the radon concentration in the basement ranged
from ? to 16 pCi/L, averaging 1 pCi/L. The higher- concent i atior.s weie
associated with water use.
The family rooin in this house is on a grade level slab extension. Vow th.it
the radon supplv via the basement had been reduced, there was a concern that
the slab might have snme significant : adon entrv loute*,. Veasui einerits ..ps lairs
-------
in Februarj found that concentrations ranged from 0 to 9 pCi/L, a\eraging
2 pCi/L. The small peaks Vvere associated with water use.
Alpha Track detectors were placed in the house in March and removed in
May 1936.
2.3. PHASE 3
In November 1986 the basement radon concentration varied from 1 to
41 pCi/L, a\eragmg 9 pCi/L. The highest concentration was associated ». ith use
of the cashing machine, but some high \alues occurred u hen washing was not in
progi ess, but at a time of high winds. The system v>as remeasured to sec; if
there had been au> major changes in flo\» s or radon concentrations since
February 1986.
The ladon concentration in the front wall as ci 12^0 pCi/' . »n Mie
garage side wall it was 190 pCi/L, and 60 pOi/L in the other side wall.
Concentrations uere higher in the rear wall, 120 pCi/L, and in the crawl space
walls, a\eragin£ ^0 pCi/L. The fan drew 93 L/s at 75 Pa. These readings were
all close to those found in February, and smoke tests showed 1h»t the .airflow
was frovr house to wall.
In December 1986 the radon concentrations in the basement ranged from 1
to 19 pCi/L, averaging 1 pCi/L. The high \ alue was associated with water use.
These results uere good enough to issue alpha track detectors for final
measurements.
3. OTHEH MEASl RE.MEMTS
The radiation field in and around the house ranged from 4 to 10 uR/h in
the basement, a\eragnig 7 uR/h; and from 5 to 19 uR/li on the site, typicallj
averaging IT uN/h. The highest readings uere found on the front >ard. the
lowest on the asphalt drivow ay.
Over the period March to Ma\ 1986, the average radon concentration in the
bnseiTK.'nt was 2.9 pCi/l , .ind in the li\ ing quarters was 2.1 pCi/L.
'1 he average radon ( oiiv-ent t at ion measured b> alph.i-ti ac . detoi tut i» <•>
-------
MEASUREMENTS SUMMARY TOR HOUSE 1C
PYLON AB-5 HOURLY MONITORING
PHASE MITIGATION' TEST
system dvit:
1 Weeping tils 08/85
ventilation
50 L/s
centrifugal fan
11/85
2 As abo\e Kith 11/85
direct. mounted
fan
2 Wall \entilation 01/86
100 L/s
centrifugal fan
01/86
02/86
As i'bo\ e . 02/86
Craw]space hole
seal <;d
11/86
12/8G
STATUS DURING RADON' (pCi/L) COMMENTS
TEST RANGE MEAN
Fan off 3-327 160 ovei 20 lira
Fan on 3-290 50 over 1-1 hrs
fa11j
Fan on 3-6-1 17 hr-£,
equililn imn
Tan on
Fan on -
condensation
buildup
1-an on 82-220 158 o\er 46 his
32- 73 61
87-253 164
ovei 18 lirs
o\ei 31 hi-s
(•an on 2-53
Fan on 1—16
Fail on 2-16
Far. on 0- 1
Fan on 1--1 1
Fan on 1-10
12 o\ei 4 da\s
12 ovei 1 da\ s
4 over -1 days
2 o\er 1 dj* b
9
•1
2 1-1
-------
SYSTEM M£ASCREMENTS FOR HOUSE 1G
PHASE MITIGATION SYSTEM DATE SYSTEM MEASIHI^IENTS COsl>IENTS
IliESSURE
FLOW
RADON
Pa
(L/s)
(pCl/L)
Weeping tile
11/85
105
21
Fan in box
\entilation 50 L/s
no
Direct mounted
centrifugal fan
fan
As abo\e + owner
01/86
FIoinS in
installed HRV
house:
10
5
HRY off- floor
drain
13
HRV off-supply
duct 1
35
59
HRV low-supply
due t 1
38
65
HRY high -
biipply duct 1
3
HRY off-suppl>
duct 2
43
32
HRV law -
aupply duct 2
43
39
HRV high -
supply duct 2
60
Basement air
Wall \en1ilation
01/8G
20
26
160
Pipe A
100 L/s centri filial
8
9
1 000
Pipe !i
fan
5
5
130
Pipe D
a
8
e
Pi IX? 1-
15
13
l
Pipe I
65
55
Fan duct
920
Bai-odamper
19
draft
380
ei icloseJ
crawIspace
hole
Craw 1 space holt-
02/86
ir,
2r>
Pi]>e A
sealed
13
12
Pipe B
13
9
Pipe C
10
10
Pipe D
8
1
Pipe r
8
7
Pi 1X3 G
8
3
Pipe H
\s alxnc
07/86
350
Enclosed front
wall/floor
joint
245
-------
SYSTEM MEASUREMEKTS FOR HOUSE 16
PHASE
MI'I ICATION' SYSTEM DATE
SYSTEM MEASUREMENTS
PRESSURE
Pa
FLOW
(L/s)
COMMENTS
RADOV
(pCi/L)
3
Wall \enLilation 12/8G
16
23
60
Pipe A
100 L/s centrifugal
11
11
720
Pipe B
fan
11
8 1
700
Pipe C
11
8
190
Pipe D
9
4
110
Pipe I"
10
9
9
Pipe G
10
3
80
Pipe H
15
13
120
Pipe I
25
11
6
Pipe J
75
93
170
Kan duct
3
03/87
13
9
Pipe B
10
7
Pipe C
38
87
Fan duct
A -
End wall B - Front wall 1
C - Front wall
2
D -
(iarage wall E - Crai% lspace head
or
F - Craulspaee
garage v.all
G -
Cra\»lspare end i%all H - Cravlspace
rear v. all
I - Rwr ¦..¦all 1
J - Hcai
. h31 2
21G
-------
&AJgA.6-^
CM 6-fSA^E.
V*A4.;-!S:R-- '
TUB - '
WCLLOW CfNi,
©lc*=-j<
FCUMOATi^N
V/ALL-ryp
FUELL TAM<
'oo
WATECTAMK
WALL
MCUNTET*
cEhfn?i-
r FUrALFANf-
2?-^"
I ('-©'
LOW COST REDUCTION OF 1ND00H
RADON
HOUSE
B
NUMBER
FOUNDATION PLAN
Date: u/2e/SF
16
tWM
iwoximn
loMMIIM
Mitigation system: WALL AUCTION
PHASE:nWAL
247
-------
HOUSE 17
pun:nsylvania dkr me-vslrcmunts
Working Level grab samples (Kusnctz)
Short tfi'in aveiage KL (RI'ISU)
Heating season average radon (Terrade.s)
Radon concentration m water
0.130 WL
0.045 WL
9 pCi/L
4 600 pCi/L
1. UESCHIPTION
This one-stoiy house with attached gat age is built in the eai ly 1970's on a
level bite about halfwaj up a hill a few nules oust of Ooyertown. The fron.
wall is of brick, the other walls ate of siding. The house is healed b\ hot
water basebuaid radiatois with an oil-fired boiler, supplemented by a
v»ood-bui mug stove in the basement.
The basement has concrete block walls, arid is mostl> finished, with
panelled walls and a tile ceiling. In the unfinished laundry nieq, the block walls
are \ isible, and are crnrked aiourid the door and windows. The sill plate covers
the lop of the bloch walls. Thei e is a large opening around the sewer service
e.\it. The bas"inent flooi slab is a replacenn nt, pouied ovei a lav ei uf crushed
stone and a pipe nuKoi k that was placed over the original flooi to deal with
peisistrnt water leakage into the basement. The oipe nelvork leads to a sump
whe'e the water is collected arid pun pi d outside. The flooi slab is ponied
tight to the wall m the unfinished poi tio.i of the basement, but there is a
petnneter drainage slot between the wall a.iri the slab near the sump, hidden by
cove molding at the base of the finished w.t!!.
Thei e is a walk-in cedar closet adjacent to the basement stall s with a
suspended wood floor. The second floor slab is not continuous bentc.ih this
As this house had a sub-flooi pipe netwoiK a>.ressibl via the sump, suinp
ventilation was chosen as the mitigation method to be demonstrated at this
house.
floor .
\c rio\
2.1.
PJ1\S) 1
2 Ifi
-------
The sump was in a corner of the basement at the foot of the basement
stairs, and had been boxed in with panelling. The panelling, framing, and the
wooden sump forms that had been left in the concrete floor, v>crc removed. A
three-sided pl>wood enclosure was placed in the corner over the sump and
caulked to walls and floor. Expanding foam was used to fill the openings left
the wooden forms, and the accessible portions of the perimeter drainage slot.
One half ol the top of the box v.as iemo\able but sealed with weather
stripping rind screwed into place, and the other half was fixed in position and
caulked. A 4" lightweight plastic pipe ran vertically from the box, through a
hole cut in a ceiling tile, and through the header beard into the garage. A
centrifugal fan m a wooden box was attached to the pipe with f'exible ducting.
In August 198.", the radon concentration in the basement fell from -10 pCi/L
to 8 pCi/L when the fan was turned on.
2.2. piusc 2
In November 1985, cooler weather caused the water vapour in the sump ail
to condense in the flexible duct leading to the fan, and block it with water.
This was ccriected, by perfoiatmg the hose to let the water diain out, but in
Januai y l'JftS, the concenlt ation in the basement with the fail opciating properly
ranged between 12 to 28 pCi/1,, averaging 20 pCi/L.
This was compilable to the premitigation values, and was not legarded as
satisfactory jwji fonnance. Alternative mitigation methods weie consideicd. As
the basement was extensively finished, and the aveictge radon levo! was
tehitivelv hvi, installation of an air to air heat exchanger o: l.eal i ecoverv
ventilator {HKV) seemed the most viable alternative.
local conlrac'.oi who had experience with installing !!R\'s fot radon
(ontrol was asked to install a unit. Me suggested Hint the best results would
he obtains.'! if fresh air w.is delivered upstairs and stale air was exhausted fioin
the basement (a split svstem).
In Ffbi iinrj ]98P», the sump ventilation .system was renoved, and a lll.\ was
hung 1'icn: 'he floot joists ;n the unfinished l.iundi } room between the wood
stnv- and the boiler. '1 hiis was the on!) location w hei e the unit would not
sign if n a at!; affect headi owin. The flesh an intake and stale ail disihaige weie
run thiongh the ma: wall header bo «r d and siding. X divided duct hung
bene.ith th" floor joists carrier) fresh au to a flooi grille in each of the two
beoiooms a!-o\ e the laundrv mom. 1 lie dischai ge ail w.ts diawn dneeth fiom
210
-------
the laundry room, which was connected by an open doorv%av to the recreation
room. That room \w»s connected to the upstairs by the basement stairs. The
stair door v.as normally left open.
The fresh ;nr flow into the house was 81 L/s with the HRV on high, and
70 L/s on lev. As 11 o noiso was much less on low, the standard setting was
"low". The slule Mir flows vere- difficult to measure, as the duct had several
V
bends close together, but the measured flow s veie close to the supply flows, so
(he HR\ was in ftpproxiinate balance.
In l-'ebraary 1980, with the HRV on low, the radon concentration upstairs
varied between 1.5 to 3 pCi/L averaging 2 pCi/L, and in the basement ranged
f«"oin 19 to 4-5 pCi/1., ;\\ ^raging 2r> pCi/L. When the basement do<>i was closed,
the av ei age concept ration upstau s was unchanged, but basen.ent concentrations
varied between 41 to 58 pCi/l., averaging -15 pCi/L.
Although the results upstairs were satisfactoi y, the results in the basemert
suggested that the HRV had \ irlually no effect there.
A set of tests was carried out in Apiil 1986. First, the HRV was run
continually on high, turned off foi a day, then run on low. Concentrations
upstairs averaged 3 pCi'L. regardless of fan speed, and averaged 10 pCi/L with
the fan off. Cxince.it rat inns m the bi-seuient avetagod 57 pCi/L on high,
49 pCi/1. with the fan off, and 3ft pCi/L on low, confirming that the effect in
the basement was negligible.
The i.i.mi.faciui «»>•'< representative visited the site w.th the contiactoi,
rehabun ed the unit, and suggested that gieater i eductions in the basement
¦ •oncentratleas would be achieved if the HRV were installed to ventilate .no
Oasement alone. \ccorduigly, the lavout was tempo.-ai il> modified to close the
discharge to upstairs, and deliver 110 cfm of fresh air to the far end of the
recreation room. Stale air wis still extracted froin the laundi \ loom.
In -\pii: !??!>, concent i ations upstau s averaged G pCi/L v%ith the HRV fan
on high, R pCi/L with the fan on low, ti i < spect:ve of the basement doo>- being
open or closed and CO pCi/L with the fan off. In the basement, ' oncenti alions
averaged SO p<*i/l. wth the fan off, 1" pCi/I. on both high and low, and
!0 pC:/'1 on k-'w with '.he hasemi nt dnor closed.
\ final te-^t wa>- carried out in \pril I'lHfj bv leicuting the st »1 • • nr
dlsf-harge fictr. the HK\ so that it discharged into the bason'_nt. The HRV no..
2*i0
-------
acted as a simple ventilation fan delivering 6G L/s to the basement, and
recirculating 70 L/s in the laundry room.
When the fan was turned on at high the basement concentration initiallj
varied between 6 to 35 pCi/L, but leveled off at 6 pCi/L.. When the fan was
turned off, concentrations rose rapidly to average 35 pCi/L. Concentrations
upstairs averaged 5 pC"i/L with the fan on, and rose to 10 pCi/L when the fan
was turned off.
The ducting was modified m May 1986, with an additional fiesh air
discharge grille into the recreation room, and a stale air dischaige into the
basement. Uoth discharges, tie rutio of the air flows to upstairs and downstans,
and the ratio of suppl.s to discharge air could be adjusted over a wide range b\
dampers. No measurements of sjstem performance could be made at that time
for the weather uas war pi, and the "fan off" concentrations in the basement
were less than 6 pCi/1.. \n attempt \ iwv. i oiicen 11 at .v was discharged outside, not r-'ci: culaled in the fur iai " loom.
"1 ! ¦» iiiii! i.ow operate'1, is a 11K\ . Flows won* appi oximatcb 10 L/s to the
-------
family room, 40 L/s to upstairs. Upstairs concentrations initially. ranged from 2
to 9 pCi/L, averaging 6 pCi/L. After the change, they ranged from 2 to
7 pCi/h, averaging 1 pCi/L. In the family room, coneenti ations initiall\ ranged
from 14 to 32 pCi/L, a\ei aging 22 pCi/l... \fter the change, they ranged fron 1
to 26 pCi/L, averaging 21 pCi/L. In the furnace room initial concentrat'ons
ranged from 5 to 18 pCi/L, averaging 12 pCi/1.. After the change, the> ranged
from 5 tr 13 pCi/L, averaging 9 pCi/L.
The conclusion was that no significant impi ovement in perform.mce w.-s
obtained by running the system oil 100% fresh air, and the forced air flow into
the basement uas not sufficient to control the concentrations there.
The consistent diffeience between the farrnl> room and the furnat.- nyun
was remarkable, as the two rooms are connected by an open doorway. L\ea
hen the IlliV withdrew 80 L/s from the furnace room, this did not induce
enough airflow from the family room to give similar concentrations in each iooi".
The airflows into the house and the inter-floor flows were mtasui p;i during
these tests with Pl'T passive samplers. The errors in the calculated flow tales
were large (20%), due to the short t:.pe that the collectors we'-e exposed i-i " ¦
house. When Ihe 1IRV ran as a fan with no basenent exhaust, the raleulited
fresh air flow into the basement was 9 l/s, wi'n a flaw of basement an !>>
upstairs of 10.7 L/s. The main floor fresh air flr-v rat*? w.»s 31 L/s, wth i
flow of upstairs air to the basement of 9 L/s.
When the IDA' exhausted from the basoment, the calca'.atc-d fresh air flow
into the basement was 8 l/s, wt'h a flow of basement air to upstairs of a L/s.
The main florv fresh air fl >w rate GG L/s, with a flow r.f upstairs air to
the basement .it 13 l/s. These calculated basement fiesh air flows ar" nu c h
less than the ones ineasuied at the !!R\. The results wtie ivoeived loo late to
rarrv out fuither iii\ est ii; it uirs to resol\e these <1 iffe: I'liccs. Pile PF T's Jo
iiidicn!.' th.it the \ oiitilatn-n i;ilc upstairs is lughei than i.i the basi"" mi', 1
that the ti.insfei flov s between floors ai e affe.-ted :!H''e !.y changes :¦» ' 'v
system than the \ ent)l it ton i ites.
Alpha tiaeK deti i ties wue issiied in Tebru >r\ 1937 for final 'or*; teim
m« asurements.
•\ flu il test of th" sprit ia' « ariabi'it y of i adon rniicen1: at 'on w.is ca: I •< d
out lu \pi il 19ft7. '1 he l'K\ w -.s ret to supply fiish ' at 1 /¦-. to !;>•:> e:s,
-------
f>7 1/s to the basement family room, and to evhaust 57 L/s from the basement
laundry room. The radon concentrations in the basement family room tanged
from 3 to 31 pCi/I., averaging 12 pCi/L, while.- radon concentration in the
adjacent lanndty room ranged from 3 to 13 pCi/L, averaging 8 pCi/L. With tlie
HRV off, radon concentrations in the fanulv room ranged from 30 to -17 pCi/L,
averaging l>Ci/L, and radon contonti f tions in tho laundry room ranged from
25 te 37 pCi/L, averaging 31 pCi/L. Although operation of tho HRV definitely
reduced concentrations in both rooms to about 25% of the initial values, the
ratio of the laundry room concentration to that in the family room wjs
unchanged. This illustiates the difficulty of modifving the r.atui ol circulation
p.t! terns that exist in a house.
3. OTliKR MEASl'RFMFNTS
Tho sadist ion fields around and inside the house were 9 to 13 uR/h on the
site, and 7 to 9 uR/h g°nerall\ in the basement, avei aging 10 and 8 uR/h
respectnrlv. I.ocallj higher fields of 10 to 12 uR/h were found by the sump, in
tin1 cedar closet, and in other areas where a second floor slab had not been
poured.
The average radon concentration measuicd by alphn-lr«ic!\ detectoi s o.or
the period Febi uarv 19R7 to April 1987 was 7.C pOi/L m the basement, and
-l.l , ."~i/!. li: the living are.t.
2">3
-------
MEASUREMENTS SUMMARY 1-T5R ItOCSE 17
PYLON AB-5 HOURLY MONITORING
PHASE
MITIGATION TEST STATUS DURINCI RADON IpTi/l.)
SYSTEM D\TK TEST RANGE MEAN
Sump ventilation
08/85
Fan
off
5-44
28
50 L/s
Fan
on
6-21
13
centrifugal fan
As abo\e
01/86
Fari
on
12-28
20
HRV; 100 L/s
02/86
hrv
low
19-43
25
centrifugal fan
HRV
low
1- 3
O
ply
IIRV
off
8-1 1
12
arirl t1.a]e air
rifirculat inn
COMMENTS
o\er 26 hrs
over 22 hrs
still falling
over 69 hrs
over -16 hrs B
over 46 hrs U
over 15 hi's B
over 15 hrs L
o\ er
22
hrs
B
o\ er
24
hrs
B
over
23
hrs
B
over
23
hrs
L'
over
23
hrs
1'
c\ er
21
hrs
I'
o\ er
25
hrs
B
o\ er
24
hrs
B
over
23
hrs
B
o\ er
26
lirs
B
o\ or
24
hrs
r
ovnr
24
hrs
i'
o\ er
22
hrs
i.
o\ er
26
hrs
r
o\ e r
17
lirs
falL
f i-or;
35 pTi/I,
B
OUT
21
hrs
B
over
43
In s
I
o\ cr
1 1
hrs
l'
254
-------
MEASUREMENTS SUMMARY FOR HOUSE 17 (OONT)
PYLON Mi-5 HOURLY MONITORING
PHASE MITIGATION
SYSTEM
3 fresh air
ventilation
100 L/s
centrifugal fan
HRV pro\iding
upstairs and
family room
supply basement
stale air
reciiculation
3 As above HRV
supplying
upstai rs and
family room
B: Basement
TEST STATUS HIRING RADON (pCi/L) COMMENTS
DATE TEST RANGE MEAN
01/37 HRV high 5-18 12 ovei -1 dajs
furnace room
over 4 du.vs
family room
over -5 du.s s L
o\er -16 hrs
furnace room
o\er 46 hrs
famil> room
o\er 1C hrs U
01/87 HRV lugh 5-13 9 over 4 days
furnace room
o\er 1 da\s
famil> room
o\er 4 days L'
01/87 HRV high 3-13 8 over 1G Jus
furnace room
HRV off 25-37 31 over 18 hrs
furnace totw
HRV hich 3-31 12 over 46 hrs
familv r>iyin
HRV (>rf 30--17 40 over 48 hrs
family rami
5-18
12
6-30
16
2-10
6-16
5
11
14-32
22
2-10
6
5-13
9
4-26
21
2- 7
4
3-13
8
25-37
31
3-31
12
30-17
40
-------
SYSTEM MEASUREMENTS TOR HOUSE 17
PILASE MITIGATION SYSTEM DATE SYSTEM MEASUREMENTS COMMENTS
rw-ssuRt fixjk i*ado\'
Pa (L/s) (pCi/L)
Heat Recovery
02/86
8
81
Intake*
Ventilation 100 L/s
13
136
Intake*
centrifugal
13
78
Exhaust*
upstairs supply
20
100
Exhaust.**
basement e\Jiaust
69
Total supply*
4
81
Total supply**
3
31
Branch 1 *
3
45
Branch 2*
3
42
Branch 2**
HRV 100 L/s
01/86
6 4
Total suppl; *
centrifugal upstairs
25
Branch 1*
supply hasement
exhaust
As above bu? basement
0-1/86
33
67
Total suppLy**
suppl> and exhaust
63
supply to
fainil\ room**
HRV 100 l./s
05/86
5
79
Exhaust **
centrifugal fan
5
66
F supp!>**
supply to
66
B suppi\**
basement/famj1y iv>o:n
5
0. 1
I' suppl vt t
basement exhaust
Basement
Measuiements
KL F
3.9
0.018 0. 10* »
3.0
0.011 C.2H**
3.6
0.019 0.54***
3.5
0.015 0.43***
4.2
0.022 0.52***
6.1
0.021 0.39***
5.8
0.026 0.43***
Krcsh ail \enl ) lat.ion
01/87
6 ">-76
lnt -ike * *
100 L/s cunt i l filial
76
Rec l i v. * *
fan 1IR\ prcAiding
33
E supplj*1
upst.ii is .iikI f.inul\
U
I' suppl ^ *
njoni ¦-uppl\ ba^i.-ment
9
Blanch 1**
,-ffi r( ulat ion
23
Branch 2**
250
-------
SYSTEM MEASUREMENTS TOR IIOL'SF 17
PHASE MITIGATION' SYSTEM DATI'
Fresh air \ entil.it ion 01/87
100 L/s centrifugal
fail 11R\ providing
upstairs* and family
room supply lia.sement
recirculation
SYSTEM MEA3t JREMENTS
PRESSI "RE FLOW RADON
Pa (L/s) (pCi/L)
42
43
9
24
cxy-riENTs
F supplyt*
U suppl> * *
Branch 1**
Branch 2**
As abo\r>
01/87
9
11
34
Fluus \la PFr
Sarap] ers
Into B**
B to U**
Tresh air Lo
B**
U to B**
UKY 100 L/s
centrifugal fan
supplj to upstairs
and faini 1 y room
basement eJiaust
01/87
8
5
66
13
Into E**
B to L**
Fresh air
L"**
U to B**
to
\s alx>\ e
01/87
56
57
57
19
54
48
49
17
Intake**
Exhaust**
F supply**
L' suppl>**
Intake*
Exhaus t *
F supply*
1. supply *
B: Basement
F. 1 ';tnu 1 \ room
L: L'p^tairs
* UR\ on lois
** 1IR\ on hifih
***IIRV off
-------
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LOW
COST REDUCTION OF INDOOH
RADON
HOUSE
NUMBER
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FOUNDATION PLAN
Date: Z/i£/&£>
17
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Mitigation
. _ CCMMEietlAL HEAT
system: v^MTii->VrUkL
258
-------
HOUSE 18
PENNSYLVANIA DER ME\SLHLMENTS
Working Level grab samples (Kusrtet/)
Heating season short term average KL (RPISU)
Heating season average ladon (lenade\)
Radon concentration in uater
0.38 J hL
0.014 \%L
12 pCi/L
1 800 pCi/L
1. DESCRIPTION
This two story liouse With attached double garage \%as built in the late
1970's ori a lev el site on the top of a iidge m a rural subdi" jsion \>est of
Ho\ei tov%n. The basement has concrete block v.alls and an external entrance.
The house is heated b> hot water iadiators with an oil-fired boiler. There is a
heat exrharigei oil the boiler chimney through which basement au fan-diiven
to be heated v. hen the bui uer is opeintirig.
The pouted cuuciete floor slab is unpuintec but partially carpeted. There
are no visible floor cracks, and no individual floor di runs. Thei e is an interior
perimeter drain (French drain) between the edges of the slab and the outer
basement v>a!!s, and a single consti uction joint duu n the centie of the floor
slab. A brick fireplace is built on top of the floor slab.
1 lie holloa ( unt i ete block v>alls hi e unf'miihod and in good condition, ^lth
no significant cracking of the mortar joints. The \>a!ls are open at the top,
aril are pc net rated b,\ service pipes fen sewage arid uatei. There is au external
striii \»ay into the basement iit the i ear of the house.
A front poi cli tonciete slab runs along the front of the house, and the
space beneath it is enclosed by concrete b!o«_k v%alls to form an unv entilated
and unhealed storage room, reached by a door in the front basement \*a!l.
'I hei e is no fionih drain 11 this space.
2. \cno\-
2.1. rn\sr i
The initiative in t-on chosen foi demonstration in this house was :9
-------
In July 1985, basement radon concentrations ranged from 6 to 31 pCi/L,
averaging 16 pCi/L.
The basement xentilation uas increased by touting a fret.li air duct from
the outside to the heat exchanger on the boiler chimney. When the burner was
operating, it uould draw in outside air to replace that lost up the stack. This
would reduce the depressurization that draus in the soil gas. The air uas
warmed before it was discharged into the basement.
The performance of this system could not be tested in the summer, for the
additional air supply would be proportional to the time that the boiler uas
operating, and should work best when the heating load uas high. Testing uas
therefore deferred until the v. inter.
2.2. I'HASbl 2
In November 1985 with the exterior air supply operating, the radon
concentration in the basement varied between 7 to 69 pCi/L, averaging
21 pCi/L. The air supply through the duct was about 22 L/s when the fan uas
off, and 3G L./s when the fan was on.
As this increased ventilation was not sufficient to reduce i adon
concentrations, a commercial heat recovery ventilator (air to air heat
exchanger) was installed b> a local contractor who hail installed other units for
radon control. His suggestion uas that the unit be installed in the base:", .'at
with split distribution. The fresh air uould be delivered upstairs thtough tuo
registers, orie at each end of the house, and the exhaust an- uould be .h.turi
dun tly from the baserru nl. This would produce the lou est radon
conr eiitrut ions in the living space. Installation was cai ried out in Februaiy
1986. 'I lit* HKV pi o\ ided 85 I/s of fresh air to the upstairs on high and TO I/s
on lou fan speed. The noise uas much less on lou speed, and the fluu s onl\
slightls lower, so the nu r.ers normally operated the unit on low speed.
Kadon concent rat ions uere measured in 1-ebruary 198G snnilt.uu-oush in 'he
basement and on the main floor. With the IIR\ on, main flooi loi'i enti atimis
ranged from 1 to 1 p('i/L, a\ei aging 2 jiC"i/L; and in the basement ringed fiom
to 21 pf'i/l., a\eiagmg 12 pCi/l..
With the MR\ off, main flooi ronci-nti ations ranged from 1 lo 11 p("i/l ,
HVi'iagm;; ft pt'i/1; and in the baser"'nl langed ftum 10 to 20 pCi/L, meragmg
lr. pCi/1..
2R0
-------
Performance of tins system was regarded as satisfactory, for it had i educed
main floor concentrations to less than 5 pCi/L. However, the experience of the
installer and manufacturer with similar systems was that basement
concentrations were general'y reduced by more than the 20% observed here.
Further investigations were carried out to see if a reason could be found foi
the lower than average reduction in the basement.
In March 1986, ventilation airflows into the basement \ la the outside air
duct were 24 !./s with the burner off, and 40 L/s with the burner on. The house
supply rate via the HRV on 'low' was -17 L/s. Switching the HRV to 'high'
increased the supply to 53 L/s, and decreased the airflow through the outside
air duct to 21 l./s, suggesting that the effect of the HRV was to pressuiisf the
basement slightly.
In March 1986, tadon concentrations in the basement anil on the main floni
were 10 pCi/L and 0.8 pCi/L respectively with the HRV on 'Low'; 10 pCi/L and
1.0 pCi/l. with the HRV on 'high'; and 11 pCi/L and 2.1 pCi/L with the HRV off.
The HRV manufacturer's representative and the installer \ lsited the site at
the start of this test, and found that exchanger was appai entlj unbalanced,
with the exhaust flow exceeding supply flow in the ratio of 3 to 2. -\ dampei
was readjusted to balance the flows.
<\ stiff brer-;'e was blowing at I he tune of the measurements, jind it was
sugg'-sted that the change in HH\ balance since installation ma\ ha\e Ij'.-i n
caused bj a nonuniform wind piessure distribution on the HRV e.xterioi int.il.e
and e.xhaust points. These were located on the rear wall of the house, neat the
corner, separated b% about 3.5 m.
The representat i\e recommended that the basement door uiideicut be
inr i-RrisoJ f i om 2 to 4 cm to provide a groatei return ai: flow from the u. :in
floor. This was done after the short term measurements weie completed. He
also suggested that the upstans air might be tia\elling duectly to the l'.R\
i.ather than nu\ing with the basement au generalh, and so the monitor
-------
2.3. PHASE 3
In February 1087, ihts radon concentrations wero meusuied upstaus and in
th-s basement villi the ltK\ set to \entilate the basement alone. '1 he- dueling
vas modified to dehvei an to the far end of the basemcnl fiom the HR\
e\haust and angled 'O pi omote circulation in the basement. In tins mode the
upstairs ladon concentrations ranged fiom 1 to 7 pCi/L, with ,in a\ erage cf
4 pCi/1.. *! lie basement itidori concentrations i anged from 7 to 2G pCi/L, viilh an
a\ erage of 13 pCi/L.
The ducting uas then returned la discharge air upstairs unlj. Radon
concentrations upstuu s ranged from 1 to 4 pCi/L, a1, ei aging 2.5 pO/1., while
ennceutraUr lis in Ihe basemenl ranged fro-n 10 to 37 pOi/1,, el\ ei ugm:; 1-3 |>C:/L.
When the K1JV was turned off, upsU.us radon < onccntE atiuns ranged from 2 to
15 pOi/l , aw.-iagmg 9 pl'i/L, and basement i adon concentrations i angrd from ]G
to 3f> pOi/L, a\et-agmg 2-5 pCs/L.
The ba-spment and house ventilation rates and inter-flooi tiansfi'i i ates
\ieie measuied with pas-ax s Phi t facet isocu cet and collectors. I h" .:."t ui acj of
these ineasui enients iias low (20?^] is onlx one source h jb used or> ojlIi floor,
and the detei.toi s w ert depJov'"^. Tor oriI\ two or tluei: da> s.
When th" Ilia set to \entiHte on!;/ the basement, 11je flaw into
basement ^ris THr> I /s, with :i Li-uis>f«r flo» to upstnn s uf j9 L/s. 1 he an flu
t»iiL oT the ni'iin floor was 2G5 L/s, intli a flow into the basemen,. of I L/s.
Mien I lie HIi\ i>dt, set La dehvei air up^lmss, ,md exhaust fiom the h.isrmiii'..
the inflow into the basement whs 253 L/s, \* jtli a flow to upstaus of 50 L/s.
'! In- airflow ouL of the main floor was 1"~7 L/s, with a flow into the basenenl of
A t /%.
During these le*-ts the !!K\ deli1 ered air to the b iscnu'iit at b7 L/s, md Vn
thp upstairs at 67 L/f., and cshausle'! at about SO L/s. The airflow oat of the
baseirx nt % tu the hasene.it dooi undeieat was mtv.suret! at 53 L/s, when the HR\
i.'as disrhai g, eg air upstairs. I"\ ¦ n tlio'J^h '¦ he calculated flows are «»nl> i,'ood to
about 20%, it is plain thai the basf.ir.ent and nun ffooi aitf'ows .*:t j'". • h
target than thos« plod need b\ the Ilh'\ , Find the effe< I uf ill inges In 11 ^ li-ude
of i.peiaLion ate small - pel haps smai'tei t'lan ti'.use c.tusi J b\ Wt .it'lei t
'llus max I'e til'* e\plan,i i.jri uh\ tht immmii ,j>l fitsh in fkn. tu up.'.ins snouL1
he siiialtej n.h("t| the !Ui\ is disr lun gniC 07 l./s upstairs 1'ian u litn the1-1 is r >
ifl'll I K»rial rle<-h .ill tti, till.
2T.2
-------
This series of tests showed that the poor basement performance of the HRV
was not a measurement artefact caused bj inadequate circulation, or by
insufficient return airflov* from the upper floors, it was simply that the natural
basement ventilation 1 ate uas higher than that pioduced b> the HR\, and the
percentage reduction in radon concentration was correspondingly louer.
Alpha track delecto) s were issued :r. Febi jary 1987 for final long tei n
measurements.
'A. OTHER MEASUREMENTS
The radiation field in and around the house was 5 uR/h m the basemen1,
and 6 to 7 uR/h on the site.
The average ladon concenti ation tne.jsuied by alpha-ti ack detectois over
the period Februarv 19K7 to April 13P7 \%as 8.S pCi/L in the L^tenitnl, a;.d
2.1 p'"i/L. in the living at ea.
•jr.'f
-------
MEASUREMENTS SU^IAHY lOR HOUSE 18
PYLOV .\fi-5 HOCRL\ MONITORING
PHASE MJTTGYTION TEST
SVSTi:-! D-YI'L
ST-YRS DICING RAHG\ (pCi/L)
TEST RANGE MEAN
COMMENTS
1
lYoini t ijiaLion
07/85
Si.r\ ey
6-31
1C
o\ er
-IS
hr=s
o
J ncreused
11/85
\ e-it
uiit. on
7-G9
21
o\ or
CO
hi-s
\ cnLi 1 at. i or
fresh nil' dueled
1 O tlMt
(welianjjer on
lxiiler r-h'.iinej
«•>
HR\ upstairs
02/8(3
HRV
or.
5-21
12
o\ cc
IS
hi-s
»
supply
urn
on
1- 1
o\ t:r
IS
ht
L
HRV.
off
10-21
15
o\ ex
4 1
h:~s
B
11RV
ofr
-1-11
8
ove r
-15
hrs
!.
2
IIRV upstairs
03/86
HRV
on ] ok
7-14
10
o\ er
15
li!-S
B
supp]\
HRV
Ol 1 1 ow
0.1-!.
.4
0.8
o\ er
15
h-.s
I"
HRV
on high
7-1 1
10
o\ ei
21
tutf
B
HRV
Oil hlCh
0.3-1
, o
1.0
U\ fl'
24
li!-S
V
HR\
off
7-1S
11
ovet
2i'
l«ti#
B
HK\
off
0.1-4
.6
2.1
o\ er
29
hrs
L
3
llh'V b-isu'IVP t
02 '87
HRV
or\ lii'^li
7-20
13
o\ OI
4 <
•>
•=¦» 1| »Jjl v
HRV
•"ill !vgh
1-7
1
o\ er
-1 «
R\ s
i
||R\ i.psiairs 02/87 HRV on l.ou 10- 37 15 ovei 111. B
supp]\ " 1 - -1 2.5 " I'
HRV off Hi- .?"> 2-1 o\ei $-> h B
2- «:> 9 " l
R>t^( -nsonl.
I • 1 | • -. I u rs
;'R\ ll( ¦ 11 ill f i >\ •>/ y
\ rnt j ! itcv
-------
SYS-jEN measurements POH HOUSE 18
PHASE MITIGATION SYS^jN DATF
2 H]i\' upstairs suppl\ 02/86
2 lfli\ upst_.il Th> hUppl> 03/8G
3 HR\ basement supply 02/87
02/87
SYSTEM ME/XSLHEMEVTS COMMENTS
ESSURE FLOW RADON
Pa er off
HRV supply !ca>
-1
39
GAB «_.:Y
9
39
HRV supply
high
<1
21
OA! 1 off
1 ^
17
l£Tf\ s.v,pp!;«
high
4
33
0\P, o»j
14
15
HRV -.uppl%
high
8
O.S
0\n l.lockod
8
41
HRV suppl\ low
10
0.5
OMJ blix-Kod
13
56
HR\ suppl\
high
88
High MippJ\
(>7
I/3K si:ppL\
t'Fl lesult^
1S5
mt.o basement.
5!)
biiscnicat. U<
li[)Sl a j rs
265
out of
1
upstai¦s
tipstinrt, to
tMsoment
205
-------
SYSTEM MEASURI^JENTS FOR HOISE IS
PHASE MITIGATION' SYSTEM DATE SYSTEM MH-\SfRE>!ENTS COMMENTS
PRESSURE FLOW RADON'
Pa (L/s) (pCi/L)
HRV upstairs supply 02/87
HRV upsta l rs supp] ,\
HRV upst-^iis supply 03/87
2-1
K -supp I,\ low
43
D.lin -supp!)
low
PFT resu] 1 s
253
into bdSLiii'^nt
50
basement to
uj*i ta i i s
157
out of
ups ta11s
1
upstairs to
b'tseinent
!8
GG
A - In f£h
13
57
A -low
13
92
B -high
10
79
D -lou
10
78
C- high
8
7 5
C-ltw
59
outflow \ia
undercut
A: Fresh air intake
B: Exhaust.
C: Tata] supp]v
1): F.u- supply branch
h: Kitchen
O.Rn;: Dinnvi rooin
IFRV: Heat Rf»co\ t>r.\ Ventilation
OAR: Outside Airxiurt Blower
2GC
-------
FlIZEJPL-AjCt
WINDCW
-rtr.
6H-CCK R^JCC-TIC*,'
WALL- TYP.
Hr?i_i_cw c-tkic.
WALL
V*
-T
P&ZZZtf 5LA&
ife^VE)
RISER TO !?£:£)STCS"-
IMUVikJi; ^RA£.£
0"fe
io'-o'
1
TV/g C^sg. &A.gAv6-E.
^jLAB OKI 6i2AD€
LOW COST REDUCTION OF INDOOR
RADON
HOUSE
NUMBER
IIS
FOUNDATION PLAN
Date: FHP,nf7
16
(•H'KW*
COMMEec.'AL HEAT
Mitigation system. p T^'.yri' y-"**yyr
PHASE: FiMAi.
267
-------
HOUSE 19
PENNSYLVANIA DER ME \SL REMEN I'S
Working Level grab samples (Kusnetz) 0.327 U'L
Short term average UL (RP1SU) 0.003 KL
Average radoti (lerradex) 32 pCi/L
Radon concentration in Writer 80 pCi/L
1. DESCRIPTION
This small tvo story house with attached garage whs built in the late
197C's on a sloping site pni t way up the side of a hill near Uovei town. The
walls are coveted with aluminum siding. The basement walls are hollow concrete
blocks. The central wooden beam is supported on notched blocks at the ends
at.d a block pillar in the centre of the basement. Heating is by electric
baseboards upstairs and a first floor fireplace.
The floor slab has a major crack that runs from fionl to rear of the house.
The unfinished walls aie fi ee of ciacks bu! arc penetrated by sower and water
lines. The sill plate dops not cover the voids in the top course of blocks.
2. -\PT10V
2.1. PHASE 2
The oi ig.'r'.nl intent in (.his house w.is to instill a snbfloot ventilation sjste.r>.
and seal the walls. However, discussion with the oi> ncr after selection found
that he had majoi plans for basement alteialion including installation of a
dtwi'viiy into the garage, which would requite cutting thiough the garage vail. It
was unlikely that lh«> seals could be maintained. \s a result, the plan was
changed to wall ventilation since that could deal with incieased leakage are.}, the
houso was small, the lop of walls was accessible and the floni was in good
condition. This house wall ventilation in this house.
The lop block voids weie stuffed with fiberglass insulation as support
mr.t 'i lal and cl.ised with mortar. The iiuan pockets were filled with expanding
ui ethane foam.
203
-------
Holes were cut in the second course of each wall and a 4-inch lightweight
plastic pipe installed in each ho'e and sealed in place with silicone caulk.
These wall entry pipes were connected to a 4-mch pipe running the length of
the c.ential beam. The central pipe was exhausted through a -1-inch PVC pipe to
a wall mounted centrifugal fan instulled 011 the outside of the rear block wall.
In April 1986, with the system fan turned off radon concentrations i oso
slowl> to reach an a\erage of 40 pCi/L and with the fan on concentrations fell
slowly to a\ erage aiound 12 pCi/L.
System measurements in Api il 1986 showd flows of 6 and 7 L/s out of the
three subgiade walls and 17 l./s out of the gn:'age wall. Fan suction was 13 I'a.
Radon concentrations measured 12 pCi/L in the ftont wall, 15 pCi/L in the rca:'
wall, 45 pC:/L m the gaiage wall and 40 pCi/1 in the end wall. The basement
air radon concentrations was 2.5 pCi/b at thai tane.
A smoke stick surve\ of the walls found that I lie nnflo« was positi\el\
from the house into the walls, but there seemed to be a small flow into the
liout>e from the floor crack. This was confirmed b> a small enclosure taped o\ei
the floor crack which accumulated 140 pCi/1 in 15 minutes. A sample of sub-
slab air taken through a hole diilled in the slab ga\ <_• 800 pCi/I..
In Ma\ 1986 the owner refused permiss.on '.o extend ilie wall \ •Mitikition
system lo subblab \ entilation. Concern was e.\p< essed that breaking through the
floor s'nb would lead to leakage of watei fiom below th<* slab. Smce wa!t:i
weafher had aiii\ed it was elected to await the heating season for fin thoi
nif"HSureiiit-nl of radon concenti ations.
2.2. TH \SR 3
In December 1986 with the s\ stein fan off, the laden concentrations m 'lie
basement weie 1 pf'i/L, and lose lo 17 pCi/1. when the fan was turned on. Tins
suggested that the an 1 -akage into the walls was dep-essuriznig tae !> lyen-.ent
shghtK and enc^uiaging tlie enti \ of soil gas through the floor t-irtil.. The
suction ni the walls was riot ti ansmitU d to the- subfluoi spate.
SitKe i!<¦> additional woik was permitted by the owm r, »Ipha 1 i i< 1.
detectors were issued in December 1986 to determine long tei ip a\eiages upstaws
and m the basement dm mg the heating season.
2C")
-------
3. OTHER MEASUREMENTS
The radiation field within the house ranged fiom 5 to 9 uR/h, averaging
7 uR/!i. On Dip site the fieid ranged from 5 to 8 uR/h, a\ eragmg 6 uR/h.
The average radon concentration measured v% 1111 Alpha Truck detectors uvei
the period December 19S6 to March 1987 v»as 32.0 pCi/L in the basement and
0.6 pCi/L in t >io li\ uig area.
MFLVSl REMENTS Sl^MARY FOR IKXSF 19
PYLON AB-fi HOURLY MONITORING
ST ATI. S DIRiNC RADON (jO/L)
phase MrnnvnoN test
SYSTEM D Vl'ii TT.S!
2 \nj11 \ent i lat mil 0-1/86 Fan off
100 t./s
centi i fu^.i 1 fan
Fail on
As. alw\(
12/8G fan on
liANGl! MLAN
C-43
11-51
1-1:
AO
12
10
CC^IMFVrS
10 !n ir.oa:i
aft.ei -13 hr
fjse t o
equil ibi ilbii.
7 hr mf-'.L'i
nfti-r 39 hr
fall to
equ11ibij urn
Rose; si owls
o\e» 1 davsr..
270
-------
SYSTEM MEASUREMENTS FOR HOUSE 10
ru\sE
MITIGATION' SYSTEM DATE
SYSTEM MEASUREMENTS
PRESSURE FLOW R-\DO\
Pa (L/s) (pCi/L)
Wall \entilation
100 L/s centrifugal
fan
01/86
6
7
17
7
21
43
28
59
COMMENTS
Pipe A
Pipe B
Pipe C
Pipe D
Ma:n duet for
Pipes A.B&D
At fan
0-1/8G
Pjpe \ - I rout unl ]
Pj pe C - Rear uall
Pi]*- (' - Garage *>al 1
Pij*> D - End i^aLl
12 Pipe
15 Pipe Li
45 Pipe C
40 Pipe 0
3 Basement an
800 K]oor crack-
djiect ^a^nple
120 Floor era-'k-
15 m i rt. bag
100 riour i.-rack -
15 in i n. 'ojirf
refusft) fiirt h'-i uoi k .
•^71
-------
G-AJZA&B oM erRAJsE)
4/—
-V"
0
_ »
NS
M
WALL'
MOUkTIE£>
C-EMTKiFU6AI_
Fv4U
R&£R6-UA£*>-
£ mortar.
CJI-C& UC2JE"
7W15>
M
• •
0
e
-*u-
'2.2.-C?
"V-
lO-fc"
•J'-O"
Cn
K
' * WlWDCW
"TYFT
-tra^is-jc
ET6-H
I .au-4'4?
y™-
, I U 'up
t=
t /BEAM
¦ / Ffcti COURSE. C£ l_l_"S CS-£>i?EX>
VA//l=rie>ET?iS-t-6£»e>A ^1QgTA.g^ ;
.riBE^G-LASt? AMO
./ RaAM C-t-C5»(_>BE_
-this* waul
Pte- Pipe* typ
»it_ i_ rate
¦EAuAMT
TYP.
oli. Ffc>LTU»iiTHAWEl
fv^k.1 cs;zir tH-Ai^y
O^-A&s. Fie&ER IW^OJUMIOW
TYf
hollow c^>^c>RerrE-
FOuMC^VHOM
VVAJ-4_ TYP
D>El~n^L- A RL-Av^ES)
LOW COST REDUCTION OF ENDOOR RADON
HOUSE
NUMBER
IB
FOUNDATION PLAN
Date: A/l\/&&
\°i
UtM
IHMIIIMII
Mitigation eyatam: WA,L_L_ -&UC.TIOM
PHASE:FikML
272
-------
HOUSE 20
PliVSSYI' ANIA DEI? Mk XSL'REMFNTS
Working Le\ el grab samples (husnetz) 1.021 KL
Heating Season short term average V\'L (lil'lSU) 0.170 WL
Long lerni average radon (Terradex) 210 pCi/L
Radon concentration m v»a'er 68 800 pCi/I.
1. Dt.sciurrjoN
This single stoi > house i>as built in the late 1070's on a sloping site on the
side of h hill some miles •% ^st of Olex . The wills are of siding, and heating is
hy oil filed foiced \vui m air, supplemented by ^ood stoves on the main floor and
basement.
The basement wills -ire of concrete block. Thiee vvalls ate buried, the
fourth (end) v.all contains a garage door and an enti \ door. The sill plate
cosors the blot k voids. About 80% of the walls m e covered wth ccinent-based
paint. There is n basepienl vashi'ooin.
The basement floor ^'.ab is in good rondition, penetrated bj 1 ho'lou house
jacks, a basemrnt floor iliiin, and a gai age flooi drain.
2. ACTION
2.1. I'll ASK 2
As the rtoci slab in th:s house u.is in one piece, the i:iiti gat measiue
i hiist'n fi>i deii'Oiist i at ion ::i tins house \»as sub-slab ventilation. \s the
bise»v-nt was i i'f tMiigul-ir, the nntt.d d--s>gn i*ns ror two c_\haust puints located
rill the I H||I| c line of the ment.
!\s<> 20 (in diii'ielci I', les \ -io 'lit through the flooi slab b< a loiuig dtill.
r 1 i > ¦ sulisl.ih fi'l wis of 'i. sh^d stone. A "6 iik h" \eiWal pipe of 11 gli 11» "My h I
pl.-stK mis pl.n ed in the hole, the space bctveen the pipe and ci-nciet" < l< • •-•¦d
wth asphalt . ri-n!, pr < >t- _-ied wtl. a la ei of qun k-set gloat. The v < ¦ r 11> il
pipes w-t e joined to it horizontal "0 inch" lightweight ])lastic pipe >%Iiic|i I an
along th" -nam beai.i to the gerage wall a .d was connected to a large <_eni t ifugal
fan n >ui:lt d on that wall.
In \pril l^SG, the i a'V-n ».once"t!T'.ion in the basc.'.ient with the fan on
i rnigfri fiom 20 to H.-! pCi/i., a\eiagnitr 27 pt"i/l . When the fan wis tuiiud ijff,
273
-------
the concentration rose slowly reaching a maximum of 700 pCi/L after 24 hours,
at which time the fan was turned on again, causing the concentration to fall
slowly over the next 40 hours to 2 pCi/L.
Investigation found that air was drawn down into the sub-slab space
through the hollow house jacks and at the wall/floor joint. The fan drew
1.5 L/s at 90 Pa suction at each pipe, and the radon concentration in the pipes
was 2 200 pCi/L and 2 800 pCi/L. Samples fiom the floor drains in the garage
and laundry areas respectively showed radon concentrations of C and 60 pCi/L.
The central location of the exhaust pipes produced the greatest suction in
the middle of the under floor space where there were few openings to allow
soil£as entry. The smallest suction was at the edge of the slab, where the
wall/flooi joint was a large potential entry route. If the exhaust pipes were
near the edge of the floor slab, then the greatest suction would be near the
large entry routes of the wall/floor joint and the base ot the concrete block
walls. This lav out had not been considei ed previously, for a large amount of
work would be needed to cut multiple holes with an air hammei. As the coring
drill could produce holes rapidlv, this la.sout could now be achieved at lowm
cost and with less mess.
\ccordinglv , the lavout was changed to test if the pel formance could be
improved. Txhausl locations were selected on the basis of two equally space 1
holes on each Ion..; wall, and one on the sho: t wall. An exhaust pipe c^ukl i.ot
b''- located conveniently. bv the garage door wall, and so '.hei e w«re on'.y fr e
e\!i.'iust points. The < oi »¦ cf t ill was used to cut 12.5 cm holes about cm f i on
the will. These h-.>h s partialis intersected the footing, which was biokea awjv
to ensuie that at least 00% of the hole are.M was unobstructed. Thoie wa*-
abrut 1 cm of fine material between the top of the footing and the fluoi sl-ib,
and at least G cm of crushed stone undei the floor. The fan and ceiitial
rollertion pi pct> were stil' m opei ation when the holes w-_*re dtilled. ^-uitimi
extended to the wlls, for s-iione was drawn down each hole.
\ "1 hk h' lightwiight pl'istir pipe was placed i.i each hule and the space
the p;p<- and c i'f I ct" filled with nsph lltic cement. I lie- pipes i e.n tied
to the basement ceiling and i an in the joist space to tin; "0 inch" cent i a! pipe.
In May 1980, the radon concontrat. jn in the basement with the fan on
ranged fiom 9 to 31 pC:/L, avei aging 20 pCi/I.. When the fan was turned "ff
i or.c i utivitions tanged fiom 1 ."0 to 280 pCi/L, aveiaging 220 pCi/'l..
271
-------
Investigation found that the suction at each pipe was 85 Pa. The flow and
radon concentration in the five pipes varied gieatlj; front wall 0.15 1/s at
270 pCi/L; front wall 3 L/s at 480 pCi/L; end wall -1.3 L/s at 120 pCi/L.; rear
wall G.5 L/s at G 500 pCi/L; rear wall 2.2 L/s at 780 pCi/L. Either the soilgas
concentration varied greatly from place to place under the floor slab, or else
there was considerable dilution of the soilgas at some locations. This could be
caused by house air drawn into the subslab space at ojienings in the floor slab
or by wall air drawn through joints between the concrete blocks and the footnig.
A sinoke stick check found that airflow was into the sub-slab '-pace at all
visible floor openings, but aii flow-ed into the house ft<'in the upwind sections
of the basement walls. There was a marked airflow fioni the end wjll at the
pilaster supporting the inn in ueam, with a radon t onri'ii! i ation jf If. p('i/L. T1: «-
conf'rrred that radon was entering the walls in addition lo outside .nr.
The sub-slab s> stem hid made a major i eduction in rad-ai Mipc'j rat.', »i r. t
there was sli'l a significant suppl\. !o cheok that this was not due to
floor enti routes, water was pouied into the floor dtain tiaps to ee- • i!\t'
the> weie closed, ami the hoKow steel house jacks were filled with ,|'i idn.g
foam, after sampling Radon ccii ( ntrci ous. withm the foi.i j.»'ks wcr" netsni t
as 8, 9, 1 and 1 pCi/L.
If the i.-Nhaust pipes dru.ing an the w ills .' is the l^w s •
rH'liin com eiit rat ions siifpcslfd), then thei e was a poss-hilii \ th ¦' th' m f! \
and radon suppl\ fioia the <- alls fOiilH be reduced simp'v h\ ini i is i.g !h.
>im t ight.K ss >f th*'* walls. To ' he< k th.s, the si!' p! ite was - au'k.'d to tin tip r
• lie walls, and the openings in the pilaster juvund tin- mo. bta-n we!" fillt I
with e\pandn g foam.
In Ma\ 198tf,tlie aut'ghtness of the walls wa1- ii.c'eis-'J, t ' >n
roncentrat ions in the basemen1 with the fan running ranged fion I !<¦ L'L' p("'/| ,
a\eiagirig 12 p( i/L. After the wcul was completed, the lange w.is <: < nn J t« •
22 pri/l , a\ "i ngmg 12 p("i/L.
The ( urn lusion was th".' the floni svst"m \ns wot King wdi, mo th"! r " e
pos'lne ;-t( ps to \ f ittil.sl'- ti.i: wall would be requn eJ I'-' ."-diiie 111. i.'d.ni
supjjly from that 'mile. This work i as left until the fall, when messuH : at-
t r>ulrI bt- made undei more eh il!e lgmg conditions.
27 t
-------
2.2. PHASE 3
During the suivmei of 1986 the owner extended the liouse to the rear,
almost doubling the floor area by adding two bediooms arid a dining loom on the
main floor lex el. The extension had a suspended floor, and the foundation walls
were made of concrete block, hut the soil benea'h the Hoot was covui ed with
eonctete with a loop of pet foi a ted pipe laid beneath and bi ought outside so
tint) subslab xentilation rould be added t-asilj .
In N'oveinbet 19S6, the existing sub-slab system WdS modified to \entilate
the ni iginal basement walls as well. The exhaust pipes were cut at 'JO cm fiom
the floor, and a 'Tee' inserted. A G cm dinmetei hole was cut in the block itu'l
about 25 cm fie^m the pipe, and a "1.3 inch" plastic diairi pipe pHeed in the hole
and umiicc teel to the exhaust pipe h\ a se.i les of plumbing i i due ei s.
Test.ii£ of tl:e slab and w :1' ventilation s\ stem bllowed tip- flows and
sutlio.is in the fr e wall enlr.\ pipes to be front wall 112 l/s nt 88 Pa; fiont
wall 5 L/s at 50 P.r, end wall 12 L/s ft SS Pa; reai wall 10 L/s at 75 Pa; i'-j:
wall F. L/s at 08 Pa. High turLulen' e in the ducts made .t difficult 'o ineisuie
flow,, but the flows find suctions f.>t floor entries weie found to be . fiont wall
3 L/s at 03 l"a; fiont W.:!! 2 L./s it 30 Pa; end wall 2 L/s at 35 Pa; tear wait
3 L/s 'it GO Pa; leai wall 1 L/s a! G3 Pa.
U th the s;. stc.r vi modified and -.;"-iatiug : adon cii.ili ,*t t ations were found
tu range from 7 to ! 1 .»<""!/! and i\eiagr-d 10 pC'/I . Mien the fan was t l: 1 m d
off, melon e 'mi ent ¦ Minns in tin b ist irt • 1 :«>se i ."pid* . U> a high of 237 pP./!.
and ag'<1 177 pPi/i . The.' Mtui .".i li ar: a^.iagi of 10 ;• 'I. when ihe fun
w ri s tinned tin again, i ftoia C to ! r"> pt.*i/L. ! hen* I ¦** els were < ompai nhle
to thfjse- observed pi e\ im:s!. , so the change is. the s> si *ni had n.H niaH«' ." i\
niajut p"i'fin mail'e iiiipi o\ei'ient.
The effei t of the new extension !>•' radon <-oe( I'Mtl 'tuais Id till* liouse was
ni\ ignti'd b\ nie,w.renieii1 *, m ,j In'ili t*jm in I hi i xlensiun. Pone ents at inns
\ !ri''d from " to t>0 p'-'./'. al-nit a rr.i-an of 2T pCi/-., Uher a tempjia* .
("ntlifugil fai. was ted to lie* extension suf'sl ill pel i\m aled |il]>•_ s*-strip
belr.iv. ' hf < I 1 sp ii e -,1 ih, font ent: I'mns i angr-d fttni 2 t" 33 ,jCi/1, axe-aging
II p( i/3 . 11a tiinporr.i' fan deluei'd 10.30 |A'i/l. .nr it 'low iat( of .32 ! /s.
In Januai \ a mm e i omplete s*-t of me js.i i em., n t s woie , e holh in lh
basement ;uif! iipsU;1 s with the exN nsion fan o*i, then off. Basement Ie\e!s
i• "'aged 12 pf'i/1. ii i es;>ec ti\e of fan ronrl 11'oil, w In i t is the iipstans netage
27(3
-------
increased from U to 31 pCi/L when the fan was turned off. Lai go pealtn in
bast-merit concentrations (54, 88, 42 pCi/L) weie found to coincide with
laundering of clothes in the basement. Smaller tosidual peaks appeared on a
delayed basts in the upsUnrs levels. Tins was coiistslonl with the leporled f)ER
ladon in uater concentration of 69 000 pOt/L, and showed that water usage at
tins home could be -i significant route of tadon entry. None of the previous,
meiisuroments had shown lint, peaking, but when questioned, the owner re\ejler!
that clothes ".wis'iinij hod been avoided rtunny all previous test peuods.
In 1987, a lui ye plat tie bodied centLifugul fan was installed lo
replace the basement s> stem fun operated at a suction of 150 Pa lo
provide s'.em in operation, radon coiiLenti itioiis '.:pst:iirs»
avei aged 12 pfi/! , v^ith rnnge 3 to -17 pTi/1 , arid in (he b.iseMient tadon
concentrations 8 pf. i/l., v-.iih lanyo of 2 lo 65 pOi/L. Once again thei e
were t idon pen I. h \ V.n i lolhos > i-re washed >n the bfrsemei 11. At ti.iies hen
ihe1 v' \>*is no wati.-i use fot hoius, 'xisc nii-nt <-onceuli ations ranged fiuin
2 pC"i/l to 30 pCi/L -bout ft mertn of 5 pCi/L. Verv l.u ge peal.s ueie obsei v< d
upBi.Ti's folio«.:n(j shniw*i>> mid briths. This evplnum li\ the upstair-, .s
Inrtre: than the bJisurieut mm/., since v.ith a faimlv of foui childiou, baths and
shoh'T1. fi f frequent oc ui I entes.
In l,il<- ^'-ijcli 1087 i jjdoi1 iorn.cnti 'it'mis upsl.ms rmd in the base.>'« n' v,,i'_-
rron.torcd shil" Hi,files m lh- s\ st.'in ue.v ml i odueej. ' u •-1, 111'- -4c
sui tr.ni i ri t'i" b.'isi-iti" lit s\ stent vnt>- mc reined ft on 80 Pi to I'D :\i bv n.' i
drtmpi. i ¦ " the p>P" ii K 11 t-C the basement s;. sti in to !'"• extension!. \e^'' i_ tmij
pofilrs t!>"< to v>nlei as li'don r.oi-< eutt at ions .ipst. irs iik 'easei', fio'i- "jji
11 hour f.\ ci age of thun "t p(."i/L to ;in 11 lioui ,i\ei ;iCt of cm j ip'Si.'K,
.uul in tlie ons'-in^nI increasctl rr'>m a 2-! houi rAi'ivi^i1 of J pCi/l lo a 'J 'tn.u
• i'v.i.'-re 5 pC:/!<, cl'-^jjite tli „' if. i east i.> st'-i'i suction.
-------
The pipes into the walls were then disconnected, turning the system into a
sub-slab system only. This increased the average suction at the floor from
110 Pa to 220 Pa. Theie was no significant change in the lowest radon
concentrations measured in the basement which averaged 7 pCi/L, or upstairs
which averaged 8 pCi/L. The improvement in sub-slab system suction did not
seem to decrease the radon entry rate from the crawl space either. Flows and
radon concentrations in the floor pipes under these conditions were; front wall
0.3 L/s at 260 pCi/L, 6 L/s at 330 pCi/L; end vail 10 L/s at -500 pCi/L; rear wall
12 L/s at 5 800 pC'i/L, 3 L/s at 680 pCi/L. Smoke testing showed that Ba-
rlow ed from the house into the walls through the openings left b> removal of
the pipes, except at the first opening on the front wall, where there was a
steady airflow of 0.5 L/s at 17 pCi/L into the house.
To detei mine if an optimum setting of the extension line damper existed,
the damper was opened, and the flow vai led from 27 to 38 to 51 L/s, still with
the wall pipes disconnected. When radon peaks caused by water usage were
relieved from consideration the upstairs averages lay between 5 and 6 pCi/L and
the basement a\ erages lay between 4 and 5 pCi/L. Therefore, provided the
extension s> stem damper was at least partly open, no significant difference in
radon concentration was observed. This was understandable as the s> stem
suction remained high, deci easing onl.'. from 212 I-'a to 167 Pa as the damper
position was vai led from nearly closed to completely open.
As a final test, the damper was left fully open, and openings in the walls
where the exhaust pipes enteied were first taped closed, to check the effect of
closing the walls, and then wall suction pipes wei e reconnected. Upstairs radun
concentrations (discounting water peaks) showed minimal change from a large of
3 to 9 pCi/L and an average of 5 pCi/L; to a range of -1 to 3 pCi/I and a\eiage
of 6 pCi/L.. Basement concenti ations fell from a range of 3 to 10 and an
average of 6 pCi/I.; to a range of 2 to 6 and an aveiage of -1 pCi/I. when the
walls wiMH \entilnted, thereby confirming the hollow block walls as a small route
of radon cnti'j .
\lpha tiack dotrctors weie issued in "Mai rh 1987 to mnnsur< a longer term
average radon concenti ation.
278
-------
3. OTHER MEASUREMENTS
The well uater radon concentration was remeasured by DER in Apitl 1987.
They found that the concentration was. 112 500 pCi/L, significantly higher than
the previous \alue of 68 800 pCi/L. This concentration was comparable to that
measured in house -30, where the water uas the major route of radon entry.
The radiation field in the house ranged from 6 to 15 uR/h, aveiaging
9 uK/h. The higher fields were in the vicinity of the hot water tank, Ythich
gave 39 uR/h on contact. The radiation field around the outside of the house
ranged from 11 to 27 uR/h, averaging 16 uR/h. The highest readings uere near
the bank into wiiich the house extension had been set.
The average radon concentration measured by alpha-track detectors o\ er
the period of March 10S7 v>as 5.8 pCi/L in the basement, and 9.9 pCi/L in the
living area.
273
-------
MEASUREMENTS SUMMARY FOR HOUSE 20
PYlJOV AB-5 HOURLY MONITORING
PHASE MITIGATLON! TEST
SYSTEM DATE
2 Central sub-slab 04/86
ventilation,
100 L/s
centrifugal fan
STATUS DURING RADOV (pCi/L}
TEST RANGE MEAN
Fan on 20- 33 27
Fan off 98-696
Fan on 527- 22 -
Peripheral sub- 05/86 Fan on 9- 35 20
slab Fan off lf)0-280 220
ventilation;
100 L/s
centrifugal fan
05/86 Fan on 4- 22 12
Fan on 4-22 12
Basement sub- 11/86 Fan on 7- 14 10
slab and wall Fan off 96-257 177
ventilation; Fan on 6- 13 10
100 L/s
centrifugal fan
Plus crawl space 01/87 Fan on 5- 60 27
sub-slab
ventilation;
50 L/s
centrifugal
01/87 Fans on 2-55 11
01/87 Fans on 3-88 12
Fans on ''-IS 11
~ Fan off -1- 6 12
~Fan off 13-82 31
COMMENTS
over 25 hrs.
over 24 hrs
of rise
over 40 hrs.
of fall
over 46 hrs.
over 46 lirs
after 4 hrs.
rise to
equilibrium
wall
airtightness
increased
oxer 18 hrs.
o\er 18 hrs.
oxer 34 hrs.
after 18 hr
return to
equilibrium
over 2 days U
over 2 da\ s I!
o\er 2 da\s B
over 2 da> s I
over 2 da\s II
over 2 da,\s I
280
-------
MEASUREMENTS SUMMARY FOR HOUSE 20 contd
PYLON Ali-fi HOURLY MONITORING
PHASE MITIGATION TEST STATUS DURING RADON (pCi/I.) COMMENTS
SYSTEM DATI- TEST RANGE MEAN
crciv.'\ space
+basement sub-
slab and wall
ventilation 150
centrifugal fan
03/87
Fan on
Fan on
Fan on
2- G5
3-- '17
2- 10
8
12
Neglecting water peaks froin hero onward
3
over 4 da\s B
over 4 days I'
basement
neglecting
water |x?aks
crawl space Jino
r-
oc
N
=i-
opn
1 5
3
over
daniperod
Damper
opn
2- 1
3
ovo r
Damper
clsd
-1- 9
7
o\ er
Damper
clsd
11-14
13
o\ er
line dampered
03/87
Damper
clsd
5- 8
7
o\ or
+wall pipes
Damper
clsd
G-10
8
ovei
removed
04/87
Damper
si.opn
3- 9
5
o\ or
Damper
i.1 .opn
3- 9
G
o\ er
Dumper
liiore.opti
3- 7
-I
o\ or
DJiinjw'r
irore. opn
o— t
5
o\ er
D-imprr
fl Ij".opn
3- 7
1
over
Dumjx. r
fl 1;. .opn
1- 7
G
over
line dajii|>ere«J +
0-1/87
Damper
fl 1 y. opn
3-10
G
over
wall openings
Damju^r
fl1\.opn
3- 9
5
over
<_*1 osed
lij»» (lappet ed +¦
01/87
Dnmper
f11\.opn
2- G
1
o\ er
«-TI 1 1 piJX'S
Djur.]>v r
ril\ .opt".
-1- <3
G
over
37 lii& B
25 hrs U
¦11 hrs n
I <'ci iritK.'d <;i I
* Craul c c fi\n
li R-lt.1 Til' nt
U b'jixt ,u I
281
-------
SYSTEM MEASUREMENTS FOR HOUSE 20
PRASE MITIGATION! SYSTEM D-\TE SYSTEM MEASUREMENTS COMMENTS
PRESSURE
FLOW
RADON
Pa
lab
05/86
85
0.2
270
Riser A-Front
* erit ilatjon 100 L/s
85
3
480
Riser B-Front
centrifugal Caii
85
4
420
Riser C-End
65
i»T
1
6 500
Riser D-Rear
B5
2
780
Riser E-Rear
S
End uall
pilaster
05/86
ft
House Jack 1
9
House Jack 2
4
House Jack 3
4
House Ja-: k !¦
Basement sub-sl at> arid
01/87
86
12
A- vail entry
wnll ventilation;
63
3
A- slab entrj
100 L/s centrifugal
50
5
B- wall ent r>
fan
50
2
D- slab entry
88
12
C- v.nll entrj
55
O
C- slub entry
75
10
D- wall entry
50
3
D- slab entry
38
8
E- Kail entry
63
1
E- slab entry
As abo\e plus crawl
01/87
52
1
050
At cra<-. 1 space
space ventilation;
fan
50 I/s. centrifugal
fan
Crrn.l space «-
03/S7
Go
52
1
100
Cl-iu] S|X1CC
liasemotil sub-slab and
pi }•»! to tee
will bit jon;
50
12
1
700
D iiher to lee
150 L/t> centrifugal
150
06
550
Mun duct riL-i
fart
282
-------
SYSTEMS MEASUREMENTS FOR HOUSE 20
PHASE
MITIGATION SYSTEM DATE
Crawl space damper
open
03/87
Crawl space damper
closed
03/87
Damper closed + wall 03/87
pipes removed
Pipes + damper
partly open
04/97
SYSTEM MEASUREMENTS
PRESSURE FLOW RADON
Pa
95
62
100
50
95
70
112
100
112
100
112
75
67
237
212
224
249
187
199
212
199
212
(L/s) (pCi/L?
16
12
17
12
13
45
17
13
17
16
16
4 560
7 8 500
34
310
560
2 200
0.
6
10
12
3
41
9
38
260
330
400
5 800
680
2 900
COMMENTS
A-Riser
B- Riser
C-Riser
D-Riser
E-Riser
D-Horizontal
D-Wall
A-Riser
B-Riser
C-Risei
D-Riser
E-Riser
B-floor
D-Riser
D-Horizontal
A-Floor
C-Floor
E-Floor
A-Riser
B-Riser
C-Riser
D-Riser
E-Riser
D-Hori zont.il
D-Riser
D-IIorizonta]
Main Duct
Pipes + dam)>?r
moie open
162
167
174
7
45
D-Riser
D-Riscr
Main Diict
Pipes + damper fully
open
117
122
167
I
61
D-Riser
D-Hor i -iontal
Mam Duct
283
-------
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HOUSE
NUMBER
20
284
-------
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HOUSE
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Date: 2/27/ffV
20
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Mitigation system: WALL/'Su&'SlABf3UCTlc?N
PHASE: FiMAL
285
-------
house; 21
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Heating season short term average KL (RPISU)
Heating season average radon (Terradex)
Radon concentration in water
0.553 KL
0.465 WL
172 pCi/L
1 100 pCi/L
1. DESCRIPTION
This single story house with attached garage was built in the earlj 19GQ's
on a sloping ruial site on the side of n ridge a feu miles west of Boyertown.
The house walls are faced with brick, and heating is by oil fired hot water.
The garage floor is on the same level as the basement floor, and there is a
door from the basement into the garage. The basement walls are of concrete
block. The block \oids are open at the top, and are partialis covered by the
sill plate. Almost all of the basement is partly finished. The walls are pointed,
there is a suspended cening, and a carpel is glued to the floor, except for a
basement washroom that is tiled, and a small laundry area where the concrete
floor is exposed. The well picssure tank is supported bj two conciete blocks
laid on their side. The voids penetrate the floor.
The owner said that there was a weeping tile drain round the house, which
drained to a lower part of the site. Theie is an untrapped floor diain in the
laundry room that probabl.% connects to the weeping tile. There is a gap
between the edge of the drain and the concrete.
2. ACTIOV
2.1. PHASE 2
As this house had a weeping tile drain, the mitigatne action chosen fo1
demonstration was weeping tile ventilation. An examination of the situ ct-uld
not find the dischaige pipe from the weeping tile.
The situation was reviewed in detail. The garage slab was at basemen'
flooi le\el, and the garage had been added to the house. It was hkeh that the
path of the original diain line was below the garage slab, and the di.-m t;!e
along the house wall nnght well ha\e boon damaged or removed during the
garage floor slab installation. It now seemed as if a major excavation would be
28C
-------
required to reach the tile, rather than a simple job requiring only a minor
amount of digging. There was no assurance that the tile would be co: unuous
round the house as needed for a satisfactory soil gas collector.
In light of this, it was decided not to pursue the seeping tile route, but to
examine alternatise mitigation methods. The gap uround the floor drain was
large enough that crushed stone aggregate could be seen beneath the floor Elab.
A concrete coring machine had just b<-en made available, so it was decided to
demonstrate sub-slab ventilation as the mitigation method in this house.
The only part of the basement floor that was not covered villi glued carpet
or tile was the laundrj area. An 20 cm diameter hole was cored through the
floor adjacent to the furnace and out of the main traffic pattei n, aid a "6
inch" lightweight plastic pipe was installed in the hole. The sub-slab fill was a
layer of coarse crushed stone 8 to 10 cm thick. The gap between the slab and
the pipe was filled with asphaltic cement and protected with a layer of fast-set
grout. The other end of the jJipe ran to a lai ge ceil' rifugal fan mounted on a
sheet of plywood that replaced a basement window. The unt lapped floor drain
was closed with an expanding rubber plug.
Tn April 1986, the radun concentration in the basement with the fan off but
the unirapped floor drain closed, langed from 26 to 20! pC/L, averaging
1G0 pCi/L. When the fan was turned on, concentrations fell for 15 houis to a
new equilibrium winch ranged from 8 to 16 pCi/L, averaging 12 pCi/1. ever the
next 12 hours.
I in estimation found that the fan developed 85 Pa suction at 12 L/s, with a
radon concentration of 2 300 pCi/L in the exhaust. Smoke tests showed airflow-
was down into the sub-slab space at all ciacks in the laundry room end and
round the edg-> of the flooi dram. Wher the plug was i emoved fruin the
untrapped floor drain, there was a flow of 0.7 L/s out uf the drain at 2
000 pCi/L. Glued carpet and baseboard heating units prevented smoke tests on
the r'-nainder of the basement floor.
2.2. PHASE 3
The fan installation was not satisfactory for a permanent installation, so m
No\ timber 198R the fan was replaced with a large plastir body in-line
centrifugal fan attached to the wall. The plywood panel was replaced b\ a
sheet of plexiglas with a hole for the duct to pass through. The gap between
the edge of the floor diain and the concrete was closed with silicone caulk.
287
-------
The new fan produced 300 Pa suction at a llow of 77 L/s, and a radon
concentration of 1 100 pCi/L.
In December 1986. after the fan change, the ladon concentiation in the
basement was monitored. When the fan was turned off, concentiations ranged
from 38 to 116 pCi/L, averaging 7G pCi/L. When the fan was tuined on again,
concentrations fell over 8 hours to an equilibrium ranging fioin I to t pCi/L,
and averaging 3 pCi/L over 38 hours.
Alpha track detectors weie issued iri December for final long leiin
measurements.
3. OTHER MKXSU'JEMENTS
The radiation fi id m and abound the house ranged from 4 to 7 uR/h in the
basement, averaging 5 uW/h. On the site the field ranged from 7 to 12 uR/h,
averaging 9 uR/h.
The average radon concentration measured by alph i-track detectors o\c-i
Lhe period December 198G to March 1987 uas 3.1 pCt/L in the basement, and
2.6 pCi/L in the living area.
288
-------
MEASUREMENTS SU^IARV FOR HOUSE 21
r\F.CN' AB-5 HOURLY MONITORING
PHASE MITIGATION TEST
SYSTEM DATE
2 Sub-slab 04/86
\entilation;
100 L/s
centrifugal;
untrapped floor
drain plugged
3 Sub-slab 12/86
ventilation;
150 L/s
centrifugal;
untrapped floor
drain plugg^-d
STATUS DURING RADON (pCi/L)
TEST RANGE MEAN
Fan off
Fan on
Fan off
Fan on
26-201 160
8- 16 12
38-116
1 -1
76
3
COMMENTS
over -M hrs.
over 31 hrs.
after 15 hr
climb to
equi!; 'riim
over 17 lirs.
o\er 3S hrs.
tift-cr 8 hrs.
SYSTEM MEASUREMENTS FOR HOI SE 21
PHASE MITIGATION' SYSTEM DATE
SYSTEM MEASUREMENTS
PRESSURE i-"LOW RADON
I'-a (L/s) i pCi/L)
COMMENTS
Sub-slab ventilation; 01/86
100 L/s centrifugal
fan; untrapped floor
drain plugged
Sub-slab \entil.ition; 11/86
150 L/s centrifugal;
untrapped flooi drain
p] uggod
8=5
300
12
0.1
2 300
2 000
1 100
a' fan
drain w-hen
unplugged
At fan
283
-------
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290
-------
HOUSE 22
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Short term average VL (RP1SU)
Heating season average radon (Terradex)
Radon concentration in uater
0.170 WL
0.029 WL
24 pCi/L
8 000 pCi/L
1. DESCRIPTION
This two story side-split house uith attached garage v>as built in lite eatly
1980's on a gently sloping site in a rural subdivision near the top of a lull a few
miles v.est of 01e>. The lower half of the walls are of brick, the upper half are
of siding. The garage and a family room are on a slab at grade level, and only
the living room is over the basement. Heating is by oil-fired hot vater in
baseboard con\ectors, with an upstairs firo place in the family room.
The basement walls are of poured concrete, and there is an external
entrance. There are water stains on the concrete in tile right-hand corner of a
step in front of the external doorway. There are no cracks in the f'ooi or
walls, and the wall/floor joint crack is small. The family room floor slab lies
partly on top of the basement stub v.all. The junction is lai gely concealed by
the doubled 't\»o by four' sole plate of the dividing frame wall uhich stands or.
top of the stub vail in front of the slab. In the few places here the joint was
visible, there was a large gap between the top of the stub v.all and the
underside of the slab. The boiler chimney is made of concrete blocks and passes
through the family room slab adjacent to the stub ws.ll.
The ou ner said that there uas a seeping tile drain around three sides of
the house outside the concrete vails.
2. ACTIOS*
2.1. ph\si: 2
As the joinl between the stub \sall and floor slab \»as the lai gest potential
opening into I lie basement, the initial mitigation nieasute chosen fo:
demonstration at this house was a modified ^all/floor joint collection svslem.
'I his uos not evperted to be the final solut.on. but uojld provide a me isui o of
(he iel«ti\c importance of the slub \>all joint to the other loutes of entrj.
291
-------
The sole plate of the frame wall was enclosed by a plywood box. The top
of the box above the sole plate uas cut to fit round the vertical studs and
butted against the basement side of the v.allboard, which formed the back of the
box. The front of the box covered the joint between the sill plate and the stub
wall, and was screwed to a furring strip attached to the i>all. There was not
enough inborn to bo\ over the joint behind the stairs, so the stairs were removed
and the joint in this area closed with caulk. All joints were caulked to increase
the airtightness of the box as much as possible.
The stairs divided the collection bt>\ into two separate sections, which were
connected by ducts of "4 inch" lightweight plastic pipe to a similar collection
duct. A 50 L/s nxial fan mounted on a sheet of plywood m a basement window
was joined to the collection duct with a flexible hose.
In Apr:! 1936, the radon concentration in the basement with the wall joint
ventilation on ranged from 27 to 54 pCi/L, averaging 43 pCi/L. When the fan
was turned off, the concentration ranged from 26 to 42 pCi/L, averaging
34 pCi/L. The radon concentration in the three legs of the collection system
with the fan off was 2 to 5 pCi/L, and increased respectively to 23, 74 and
66 pCi/L when the fan was turned on. At that time the respective pressures
ano flows in the legs weie 23, 18 and 20 Pa and 12, 7 and 9 L/s; the
concentration in the basement at this time was 38 pCi/L. An air sample taken
from the hollow concrete chimney structure had a concentration of 32 pCi/L.
Clearl\, although there were connections to the soil in the slab/stub wall joint
area, neithei it nor the chimney was a mojor entr\ route.
Enclosures placed o\or th<* floor/wall joint on the riglil and loft side of the
external basement dooistep were sampled on two occasions with system running.
The radon concentrations one aflei 24 hours were 380 and 1 600 pCi/L on the
right side, and 80 and 80 pCi/1. on the left. This suggested that the basemen'
wall/floor joint was an entiy route, but the relalive importance of that joint and
othei joints in the sLib-on-grade sec-turn was unl.nov.ii.
In light of this, I In* second mitigation method chosen for demonstration at
this house was subsl-ib \eiitilalton of the basement slab alone.
Pour 12.5 cm diameter holes \>ero drilled through the floor slab, tuo
adjacent to the stub wall and two in the corners of the opposite (end) wall
near \\here the enclosures hud shovs n high values. Thei e uas a plastic sheet
beneath the slab, and at least 5 to 8 cm of ci ushed stone. The existing "1 inch"
202
-------
piping was extended to the holes, and caulked in place. The axial fan was
retained for testing.
In May 1986, the radon concentration in the basement with the fan on
ranged from 2 to 7 pCi/L, averaging <1 pCi/L. With the fau off, concentrations
rose rapidly, and ranged between 21 to 54 pCi/L, a\eraging 35 pCi/L.
Radon concentrations measured in the floor pipes with the fan off were;
stub wall 3 800 pCi/L (front half), 300 pCi/L (rear half), rear corner 8
000 pCi/L; and front corner 17 000 pCi/L. At that time the radon
concentrations in the basement air uas 36 pCi/L
When the fan ^ as tuined on the concentrations in the pipes dropped.
Suctions, flo\» s and radon concentrations in the floor pipes stub \»nil
(front half) 12 Pa, 0.1 L/s (no radon measurement); stub wall rear .half lo Pa,
1.2 L/s at 300 pCi/L; rear corner 22 Pa, 1.2 l./s at 5 80C pCi/L; and front coiner
20 Pa, 0.7 L/s at 7 500 pCi/L.
Further testing was halted by the onset of uarin ueather.
J!.2. PHASE 3
In November 1986 the system was modified to just sub-slab evhaust by
disconnecting the collection box, and a large plastic body e.\haust fan v.as
installed on a temporary mounting uith flev hose. Suction uas increased to
130 Pa in each of the floor pipes. Following this work, radori concent J ations in
the basement ranged from -1 to 30 pCi/L, averaging 9 pCi/L.
Flows and radon concentrations in the pipes measured in Decembei 1086
were; stub wall (rear half) 1.5 L/s at 260 pCi/L; stub uall (front half) 0.7 L/s at
1 200 pCi/L; rear corner 5 L/s at 2 900 pCi/L; front corner 4 L/s at 3
000 pCi/L.
In December 1986, radori concentrations in the basement ranged fioir 2 to
19 pCi/L, averaging 5 pOi/L. Simultaneously, concentrations upstairs ranged fron
6 to 13 pCi/L, nvBi'iigmg 10 p('i/L. This indicated that tliet e were radon supplies
to the upstaus independent of those in the basement, and that lioatmeiii of the
slab on grade portion of the house uas required.
The s\stein suction whs on!j 12 Pa ut the end of this nie.tsin emeiit pel iod,
for the flexible hose to the fan had become blocked by accumulated
condensation, ho it i»as expected that better performance could be obtained if
the fan was pel ii>rinent!\ mounted so that it would not be blot l.ed uith
condensation.
293
-------
In February 1987 the system was modified to provide suction beneath the
upper floor slab. Two suction points were drilled horizontally through the slub
wall so that the fill beneath the slab could be ventilated without installing ducts
in the finished upstairs space. The sub-slab pipes at the stub wall were 'Teed
into these holes. The fan was permanently mounted so that condensation would
not block the ducts.
The system suction was an uniform 210 Pa in all the pipes. The flow s and
radon concentration*, in the pipes were; stub wall (floor) 1 L/s, 670 pCi/r stub
wall (front) 2 L/s, 30 pCi/L; stub wall (floor) 1 L/s, 400 pCi/L; stub wall (j ear)
7 L/s, 110 pCi/L; rear corner 8 L/s, 1 900 pCi/L; front corner 7 L/s,
1 500 pCi/L. In February 1987, the ladon concentration m the basement ranged
from 5 to 22 pO;/L, averaging 9.6 pCi/L. Simultaneously, the concentration
upstairs \aried from 1 to 8 pCi/L, a\eraging 3 pCi/L. Alpha track detectoi s
were issued for fina) long term measurements in late February, at which tune
grab samples of basement air and air behind the polyethylene enclosure- of the
cellar steps gave concentrations of 17 and 19 pCi/L.
Most, but not all, of the higher basement concentrations were associated
with use of the washing machine. The radon concentration in the water foi
this house is only 8 000 pCi/L, which did not seem high enough to explain the
tieie covered by window well bubbles. Radon
conccnti at ions in the bags fit the wall/floor joint were 0 and 15 pCi/i , at the
steps 13 pCi/L, sewer pipe 0 pCi/L, beam pocket 0 pCi/L, and 3 pCi/L .ird
1 pCl/L n\ ei the windows. None of these indicated h significant i.-'don
loute. The enU \ route for the higher radon ron"ent! at ions remained
unidc rit ified.
3. fvniFN xi:-\st,Ki:vr\rs
The radiation field >n the basement i uiged ri <>*n 3 to G nR/h, .i\ei iginir
o ulf/h. The field on tin site iartg"d fiom ~ to 10 uW/h, 'i\ ri agin^ P r!C/h.
L,f11
-------
The average radcn concentration measured by alpha-track detectors over the
period February 1987 to April 1987 was 7.6 pCi/L in the basement, and 2.7 pCi/L
in the li\ )ng area.
MEASUREMENTS Sl^IMARY FOR MOUSE 22
PYLO\ \B-5 HOURLY MONITORING
PHASE
MITIGATION
SYSTIM
test status durlvg
DATF TEST
RADON' (pCi/L.)
RANGE MEAN
CXMMENTS
Stub wall joint 01/86 Fan on
\entilntion; Fan off
50 L/s avial fan
27-51 42
2G-42 34
o\er 24 Ins
over 41 hrs
Basement sub-
slab
«ent ilation;
50 !./s axial fan
05/86
Fan on
Fan off
21-51
1
35
o\or 16 his
o\er 45 hrs
Basement subslab 11/RG Fan on
ventilation; by 12/86 Fan on
150 I./s Fan on
centrifugal
Rasene'-it split 02/87 Fan on
]o\el subslab Fan on
\entilation,
150 L/s
cent!lfugal
4-30
2-19
6-13
5-22
1-8
9
5
10
10
3
over 18 hr^
over 1 davs
o\er 1 da> s
upstairs
o\ er 4 days
o\er 4 days
upstairs
295
-------
SYSTEM MEASUREMENTS FOR HOUSF 22
PRASE
MITIGATION' SYSTEM DATE
SVSTEM MEASUREMENTS
Stub-uoll joint
ventilation 50 L/s
axial fan
04/86
Subslab -ventilation
50 L/s axial fan
05/86
PRESSURE
Pa
23
20
18
F1DW
(L/s)
12
9
7
RADON
(pCi/L)
2
5
3
23
GG
74
38
32
:i 800
300
8 000
17 000
36
COMMENTS
Fan off-A
Fan off-B
Fan off-C
Fan on -A
Fan on -B
Fan on -C
Basement air
fun on
Fan on -
chimney block
Fan off-Leg 1
Fan off-Lei* 2
Fan off-Lei; 3
Fan off-Ley 4
Fan off-
basement air
12
0.1
N/A
Fan
on-1 eg
1
15
1.6
300
Fan
on-Leg
2
22
1.2
5
800
Fan
on-Lcg
3
20
0.7
7
*00
Fan
on-Leg
4
Basement subslab
12/8C
130
1.5
2f.0
Fan
on-Leg
1
\erit i lation; 150
L/s
130
0.7
1
2 00
Tan
on-Le£
2
centrifugnl
130
5
2
900
Fan
on-Lcg
3
130
4
3
ooo
Tan
on-Lc?
4
Basement + spl i t
02/87
200
1
670
Fan
¥
1
c
0
1
le±\el subslab
210
2
30
Fan
c
7
0
J*
I*
ventilation; 150
L/s
210
1
400
Fan
on-1 eg
O
ccntri fiigal
20G
7
110
Fan
on- Li a
2*
210
8
1
900
Tan
on-Log
3
210
7
1
500
Fan
on-Leg
i
17
Fan
on-
bascn;i-nt air
Fan on- ceLlar
air
Vnll M'tit ilat :on pipes-
Sub-slab ventilation pipes
A - retir B - centre C - front
! eg 1 - SI ub is-al 1 front
!jr*g. 2 - Stub uall nur
l/'jj; 3 - ictii' basement comer
! eg 4 - front basement conn-r
29K
-------
TWg guas
ELEVAn<5K( - "3-4 "
^2^=-=
UPPER Mog: -SK-AB- C?M C-(2AE>E
E"l_e,V54tTJOM
4-
*r}.*
-/i"# FVC-
r acL^y r~L_
\ -&c-A& nn
._v eg..
74'-^'
. A "<3: PVC.
• A'^FV^ *
THRU "SLAB
1 /-PtF^
6FVC.THKU''
ALL. Pv£- ¦
ELE\&T1
J <51 MT/SsLffJT\0>i
DiS^-^mMBCTEO
F=*P?=? PHA-SE. 3)
TYP.
t "^^C6sMALPLJblT
KE5 PAM
- Rp^RED
£. 'g7
22
wmniMw
IWHIIHM
Mitigation system: 6uB-6l&6> 5UC-TIOM
PHASE:Fti>JAL
297
-------
HOUSE 23
PENNSYLVANIA. DER MEASUREMENTS
Working Le\ el grab samples (Kusnetz)
Heating season short term average VL (RP1SU)
Heating season average radon (Terrade.x)
Radon concentration in water
98 pCi/L
17 900 pCi/L
0.836 WL
0.102 KL
1. DESCRIPTION
This two stor> side-split house was built in the early 1980's on a fairly
level rural site near the top of n ridge a feu miles noi th of Herefoid. The
front nnd er.d walls of the lower story are of brick, the other walls are of
siding. The family room and gurage are at grade on a concrete floor slab, only
the li\ irig room and kitchen are over the basement. Heating is by oil fired hot
water baseboard convcclois upsiaiis, supplemented with a wood stove in the
famil.v room.
The basement and foundation walls are of poured concrete. The upper floor
slab rests on top ot' the stub wall. The dividing frame wall was erected before
the upper floor slab was poured, and is supported by a row of "-l inch" solid
concrete blocks laid on their side. When the slab was poured, these held back
the concrete, pi oducmg rr>an\ openings at the edge of the floor slab. The floor
is in good condition, with minor cracks filled with silicone caulk b> the owner.
The well pressure tank stands on concrete blocks, but these rest on the slab.
The water line pusses out thiough the wall m a slee\ e. The house jacks are
hollow, but closed bv a welded plate.
2. ACTION
The initial rutigalion i:kmsuip chosen for demonstration at this house was a
modified w.ill/floor joint collection svstem .it the top of the stub wall. This
was not expected to be the fmal solution, but would provide a measure of the
relative nr.prirtani e of the stub wall joint to the other routes of entrv.
A pl.vwixid bo\ was built to enclose the floor slab/stub wall junction. As
the sole plate of the frame wall was above the top of the slab, this was used
as the lop of the box. A furring stiip was nailed to the plate, and a setond
2.1.
PHASE 2
298
-------
strip was nailed to the concrete below the top of the stub wall. A 30 cm wide
strip of plywood was nailed to the strips, forming a bo\ duct over the junction.
All joints were closed with silicone caulk.
The wallboard on either side of the stairs was cut back so that the
X>lywood could be fitted in, but there was not enough space around the head of
the stairs to run a continuous box duct there. The openings there wei e closed bj
injecting e\pandmg urethane foam. Each half of the duct was ventilated with a
"4 inch" lightweight plastic pipe, connected to a header of similar pipe. A
50 L/s a\ial fan, mounted on a sheet of plywood replacing the basement window,
was connected to the header b.\ flevibia ducting.
In *la> 1986, the radon concentration in the basement while the fan lids,
running ranged between 17 to 55 pCi/L, a\eraging 35 pCi/L. When the fan was
turned off, the concentration ranged from 40 to 120 pCi/L, avei aging 82 pCi/L.
Th is indicated that the stub wall joint was a significant route of radon entrj,
but that there were other entry routes present as well. The onset of warm
weather prevented further measurements, and further woik was delaj ed until the
fall.
2.2. PHASE 3
In November 1986, a separate sub-slab ventilation system was installed in
the basement. A 12.5 cm diametei hole was drilled through the concrete floor
slab 5 cm from the appiosimatc eentie of each basement wall, exposing the sub-
slab aggregate. A \ ei licai pipe of "4 inch" lightweight plastic was placed in
each hole and the space between the pipe and concrete was filled with silicone
caulk. The four pipes were connected to a central collection duct of similai
pipe run along Use main beam. A central \acuum line had to be rerouted to
allow this. A length of flesiblc ducting passed through a sheet of pljwood in a
basement window frame connected the collection duct to a small centrifugal fan
mounted in a bo\.
In November lrl8G, the radon concenti ation in the basemen! with both fans
running ranged finm 5 to 15 pCi/l>, a\ eragmg 9 pCi/L. U hen the stub wall fan
was tui ned off, leading the basement sub-slab fan lunnmg, the concerti alion
tanged from 10 to 39 pCi/L, a\eraging 23 pCi/L. When the sub-slab fan was
turned off as well, the concenti ation langed fiom 52 to 103 pCi/L, avei aiding
90 pCi/l.. When both fans were turned on again, the coare-iti ation fell to the
oi lgin.il 5 to 15 pCi/I lange.
209
-------
Investigation found a suction of 20 Pa in the collection box, and flows and
radon concentrations of 9 L/s, 30 pCi/L; 30 L/s, 200 pCi/L from the rear and
front boxes. The suction in the sub-slab system piping was 160 Pa in all pipes.
Flows and radon concentrations were; rear wall 2.5 L/s at 12 000 pCi/L; end v^all
4 L/s at 5 500 pCi/L; front wall 2 L/s at 50 000 pCi/L; stub uall 2.4 L/s at
1 800 pCi/L. The concentration of 50 000 pCi/L iri an exhaust pipe was the
highest measured to that time.
In late December, 1986 radon concentrations in the basement ranged from 7
to 21 pCi/L, averaging 14 pCi/L uith the stub uall fan on, and from 11 to
16 pCi/L, averaging 13 pCi/L v>ith it off. This suggested that the stub
joint v>as not a major route of entr> .
Condensation accumulated in the lowest part of Ihe exterioi flexible
dui ting, and inhibited the sub-slab fan performance. This \%as cuied bj drilling
a wcephole in the flex duct at the lowest point.
In view of the very high radon concentration!! in the soil gas beneath the
floor slab, the sub-slab fan was reversed in January 1987 to blow fresh nl: into
the sub-slab space as a test. If radon concent) ations close to the building could
be reduced, then the soilgas leakages might produce smallei radon supplies.
With both fans in exhaust, '.!iu radon concentrations in the basement ranged
from 3 to 15 pCi/l., mcrngi fg 8 pCi/l.; and in the In mg area ranged froin 1 to
9 pCi/L, averaging 5 pCi/ V>ith just the floor fan running in pressure, the
basement concentrations ivn .vd from 4 to 23 pCi/L, averaging 13 pCi/L; and in
the living nrcj ranged from 3 to 7 pf.'i/L, averaging 5 pCi/L. These
measurements interpreter! us shoeing that the sub-sLib system performance
t.ufi not improved bv operation in pressuie.
As leaks are easier to detect in pressure, a smoke stick surv ey of the
accessible basement joints and r:iai.ks v»as carried out at this tune, but found no
sign of air leaking in, ev ept fto'ti the \or\ top of the house jacks. These vire
of hol'ou pipe closed as
installed on the V.'toi exhaust sv str-m, The axial fan and plvuood sheet \%eie
removed fioin llie ind(n> frame, and the \%indov> leplaced. The collection bos
duct uas connected to the floor exhaust s) stem via ft dampei lo contiol ihe
300
-------
ait-flow. Minor openings between the vail hoard in the stair opening and the
collection box were caulked.
The suction in all the floor pipes was inci eased to a uniform 230 Pa. Flow
in the rear flour pipe was now 5 L/s, in the side wall pipe 1 L/s, in the front
wall pipe 3 L/s, and in the stub wall pipe 2 L/s. Suction in the collection box
was. set to 10 Pa by a slide damper in the connecting line to the central duct.
Flows in the box ventilation jmpes totaled 3 L/s, which was sufficient to ensure
a positive airflow into the box.
In January following this work, the radon concentrations in the basement
ranged from 4 to 15 pCi/L, averaging 8 pCi/L. The highei concentrations weie
associated with use of the washing machine. These lesults litre regarded as
good enough to justify issuing alpha track detectors in late January 1987 foi
final long term measurements.
\lpha track lesults were received in May 1937, and showed highei
cont.enti atiens in the upstau s family loom than in the basement. This might
ha\ f been due to recirculation of subslub exhaust into the upstairs. The
exhaust fan i.as re\ersed to remove all possibility of recirculation, and radon
levels in the basement and the family room \vere monitored at the same time.
The fan v«as off to start with, and basement concentrations at the start of the
monitoring were high as 175 pCi/L in the basement and 261 pCi/L upstan s.
Concentrations fell slowly o'er the three days to 30 pCi/L, m the basement
and 80 pCi/I. upstairs.
FuiIhcr radon monitoring was implemented in June 1987 when the system
had been under prossurizntion for a couple of weeks. The upstairs
concentrations wore found to range from 2 to 28 pCi/L, averaging 14 pCi/L.
The basement radon concentrations ranged from 1 to 25 pCi/L, aveia^iug
12 pCi/L. Ividently the upstairs concentre! '^ris could not be due to
re< irculatioii, and had to be due to an entry route on the family room slab.
'I he system was reconstructed. Thf> fan was ielor.\ tn the kitehiMi to access the fill beneath the family ionm slab. The
stub wall exhaust system was iftsiried.
A i heck of the i es amped system found a suction of 88 Pa in all pipes.
I lows and i ridon con'enti ations from the icar collect on bo\ were 1R !./s at
29 pCi/I ; the flow fiom th»- front coller Lion box could not be meisui"d as the
301
-------
pipe was now inaccessible. The flows and radon concentrations from the floor
pipes were; rear wall 2 L/s at 5 100 pCi/L; end vail 3 L/s at 3 300 pCi/L; front
vail 1 L/s at 14 000; stub wall 2 L/s at 5 400 pCi/L; family room slab 0.8 L/s at
200 pCi/L.
The collection bo\ pipe was dampered to reduce the flow jate, and
increased the subslab suction to 100 Pa. The owner revised the piping layout
after this.
Radon monitoring under those conditions found that both the basement and
the upstairs famil.\ room generallj averaged 2 pCi/L, except for lo\>er
concentrations found in the famil> room vhile windows were left open and
concentration peaking in the basement during times of clothes washing.
3. OTIILR ••lkASL'REMCNIS
The radiation field in the house v>as 7 uR/h in the basement, aod 5 uif/h
on the split le\e! slab. A field of 13 uR/h uas found or. contact with the well
pressure tank, but fell off rapidly with distance to 8.5 uR/h at 1 in. The field
on the site was G uK/h over the crushed stone drp'e\»u>; 12 uR/h at the sides
anr' rem-; and 510 uR/h on the fiont lavn. The site average was 12 uR/h.
The average radon concentration measured b\ alpha-track detectors over
the period January 1987 to March 1987 v. as 7.6 pCi/L in the basement f and
11.6 pCi/L in the living area.
302
-------
MEASUREMENTS SUMMARY FOR HOUSE 23
PYLON AD-5 HOURLY MONITORING
PHASE
MITIGATION
SYSTEM
TEST
D-vrE
STATUS DURING RADON (pCi/L)
TEST RANGE MEAN'
Stub wall joint 01/86
ventilation;
50 L/s asial fan
Fan on
Fan off
Stub wall joint 11/86 Both fans on
+ sub-slab
ventilation
50 L/s a.xial
50 I./s
centrifugal
Sub-slab fan
only
Both fans off
Both fans on
12/86 Stub »-all fan
on
Stub wall fan
off
17- 58
40-120
5- 15
12- 39
52-103
5- 15
7- 21
11 16
39
82
23
90
12
14
13
CONIMENTS
over 35 his.
over 32 hrs.
over 23 hrs.
over 17 hrs.
over 19 hrs.
over 18 hrs.
- after 8 hrs
to
equilibi-jum
over 24 hrs.
over 22 hrs.
01/87 Fans exhausting 3-15 8
Fans exhausting 19 5
Sub-slab fan 4- 23 13
reversed to 3-7 5
blow
over 45 hrs-B
over 45 hrs-L"
over 49 hrs-B
over 19 hrs-U
st>;b wall joint
+ sub-slab
vnntilat ion;
150 L/s
centrifi s>-L'
over 89 hrs-U
over 4 1 hrs-l
30
-------
SYSTEM MEASUREMENTS PCJR HOUSE 23
1WVSE MITIGATION SYSTEM DATE SYSTEM MEASUREMENTS COMMENTS
PRESSURE
na
RADON
Pa
(L/s)
(pCi/L)
3
Stub wall joint +
12/86
20
9
31
Rear stub wall
sub-slab ventilation;
joint
50 L/s axial + 50 L/s
20
30
200
Front stub
centrifugal both on
wall joint
160
3
12 000
Riser A
160
4
5 500
Riser 13
160
2
50 000
Riser C
160
2
1 800
Riser D
3
Stub-wall join + sub-
01/ 87
10
1
Rear stub wall
slab ventilation;
joint
150 L/s centrifugal
10
2
Front stub
exhaust fan
wall joint
250
5
Riser A
250
4
Riser B
250
3
Riser C
250
2
Riser D
3
As above with
06/87
88
16
29
Rear stub wall
revamped piping
joint.
88
N/A
110
Front stub
wall joint
88
2
5 100
Riser A
88
3
3 300
Riser B
88
1
14 000
Risor C
88
2
5 400
Riser D
88
0.8
200
Riser E
20
Basement air
100
Sub-slab
suction after
damperiny at
rear stub i^»ll
to 50 111
A: Hour wall
B: Fnd u.ill
r: Front \ m] 1
L>: St.ib u-aJ]
I.: Piumlv room slab
-------
o
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305
-------
HOUSE 24
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Short term average WL (RPISU)
Heating season average radon (Terradex)
Radon concentration in water
G6 pCi/L
11 600 pCi/I.
0.178 WL
0.002 WL
1. DESCRIPTION
This single story house with attached garage was built in the eaily 1980's
on a gently sloping site in a rural subdivision on top of a h'll a few miles west
of Oley. The house walls aie of brick. Heating is by oil-fired foiced worm air,
supplemented by a basement fireplace.
The basement is unfinished, with walls of solid concrete, except at the
fireplace. A 3 in section of the basement wall is part of the chimney structure,
and is made of concrete block. This is concealed by a b "ick facing around the
fireplace. The floor slab has a construction joint running lengthwise and is in
good condition. It is penetrated by roughed-in plumbing. The owner had sealed
the construction joint and a large portion of the wall/floor joint with silicone
caull.. A 6 m section near the fireplace was unsealed as that wall had
foam board insulation attached to it inside strapping, and access to the joint was
diffir. ult.
2. ACTION
2.1. PHASE 2
As this house had concrete basement walls (except for the fireplace
section), and the owner had already closed manj of the flooi openings, the
mrtigati\e action chosen for demonstration was sub-slab \ entilation.
The location of the sub-slab ventilation pipes was sex ere!\ consti amed b>
the ow nci's desire to finish the b.-^emen1, and his concei us about the aesthetic
impart Unit the \e: lical pipes might h
-------
of the house. Holes could not be drilled through the slab in these ureas without
a risk of damaging the sewer line.
Finally, three satisfaotor> exhaust locations were agreed upon. Two of
these were on the fireplace end wall, one in the front corner directly adjacent
to the fireplace, the other close to the rear corner. The third was at the
centre of the opposite end wall.
Holes were drilled through the floor slab at the agreed locations with a
concrete coring machine. At the corner near the fireplace the footing extended
30 cm from the wall, and several overlapping cores had to be taken to connect
to the sub-slab fill of 5 to 8 cm of crushed stone. At the other locations the
hole entered the sub-slab fill directly. The pipes were linked to a single 50 L/s
centrifugal fan via a length of fle\ hose passed through a sheet of plywood
placed in a basement window opening at the rear of the house.
In May 1986, the radon concenti ation in the basement with the fan running
ranged fro.n 3 to 17 pCi/L, averaging 10 pCi/L. When the fan was turned off
for two da>s, concentrations rose slowly over the first 24 hours to an
equilibrium ranging from 42 to 65 pCi/L, averaging 50 pCi/L.
System measurements found suctions flows and radon concentrations in the
pipes were; fireplace 100 Pa, 3.5 L/s at 2 100 pCi/L; rear wall 100 Pa, 9 L/s at
270 pCi/1.; end wall 80 I'd, 8 L/s at 550 pCi/I.. The highest concentration i.as
found in the pipe by tin- fneplace. Smoke testing at that tune indicated
general suction at tht open perimeter wall/floor joint.
2.2. PHASE 3
In February 1987, the tempoiar.v fan was replaced by a permanent lar?e
plastic bodied fan. The basement window was replaced, and the ducting
rearranged so that the permanent fan eculd be placed on an end wall of the
house aw«\ from bedioom windows. The new fan produced a suction of L'T5-
323 I'a m all pipes. Flows and radon concentrations weie; fneplace wall 3 L/s
at 3 100 pCi/I ; rear wall 4 L/s at 3300 pCi/L; end wal! 10 L/s at 1 100 pCi/L.
By this t:,r.e the ow net had completed sealing the wall/floor join', the
cential floor joint ai'd the largei floor ci neks w ith silicone caulk. A s:" < ke
survey found that the airflow was from house to sub-slab spt.ce at 3 w.
-------
In March radon concentrations with the fan on ranged from 2 to 5 pCi/L,
averaging 3 pCi/L. When the fan was turned off, radon concentrations rose to
range between 14 to 29 pCi/L, with an average of 20 pCi/L.
The difference between the fan-off concentration of 20 pCi/L in tins test,
and the value of 50 pCi/L obtained in Phase 2 can be attributed in part to the
painstaking sealing job that the owner had carried out. The quality of work
was excellent, and almost all of the accessible joints and cracks had been
covered neatly with caulk.
Alpha track detectors were issued in March to provide a long term
measurement of radon concentration.
3. OTHER MEASUREMHN'TS
The radiation fields in the house ranged from 2 to 6 uR/h, averaging
-1 uR/h. The fields on the site ranged from 6 to 10 uR/h, averaging 9 uR/h.
The difference between these fields is attributed to the basement concrete not
containing local aggregate, and therefore having lower i adioactivity.
The average radon concentration measured b> alpha-track detectois over
the period March to April 1987 was 4.3 pCi/L in the basement, and 4.6 pCi/L in
the living area.
308
-------
MEASUREMENTS SUMMARY FOR HOUSE 24
PYLON' AD-5 HOURLY MONITORING
PHASE MITIGATION
SYSTEM
2 Sub-slab
ventilation;
50 L/s
centrifugal fan
Sub-slab
ventilation;
150 L/s
centrifugal fan
TEST STATUS DURING RADON (pCi/L)
DATE
05/86
03/81
TEST
Fan on
Fan off
Fan on
Fan off
RANGE MEAN
3-17 10
42-65 50
2-5 3
14-29 20
COMMENTS
o\er 17 hrs.
over 22 hrs.
after 24 hrs
rose to
eqiul ibriuin
over 48 hrs.
o\er 40 hrs.
after 5 hrs.
SYSTEMS MEASUREMENTS FOR HOUSF 21
PHASE MITIGATION SYSTEM DATE SYSTEM MEASUREMENTS COMMENTS
PRESSIHK
FIjOW
RADON
Pa
(L/s)
(pTi/LJ
Sub-slab ventilation
05/86
100
3.5
2 100
Leg
1
2
50 L/s centrifugal
100
9
270
Leg
2
80
8
550
Leg
3
3
Sub-slab \entilation
03/87
275
3
3 100
Leg
1
150 L/s centrifugal
300
4
3 300
Leg
2
325
10
1 100
Leg
O
o
Leg 1: near fireplace
Leg 2: rear wall
l^eg 3: end wall
300
-------
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310
-------
HOUSE 25
PENNSYLVANIA DER MEASUREMENTS
Working Le\el grab samples (Kusnetz)
Short term a\erage VL erlown. The house walls are co\ered with sidmg. Heating is by forced hot
air and heat puinp.
The basement walls are of poured concrete and have no cracks. The
basement floor slab is in good condition with minimal cracking, but there is a
majoi wall/floor joint 1 to 2 mm wide around most of the flooi. The owner said
that there wrs a lajer of crushed stone beneath the floor, and that in the
summer insects entered the basement via the wall/floor joint opening. There ai e
roughed in connections for n shower and toiiet near the i ear wall, covered with
si\ bricks mortal od together.
2. ACTION
2.1. PHASK 2
As tins basement had solid conciete waifs, the mitigation method chosen for
demonstration at this site was sub-slab ventilation.
\ minimum four point system iiiis installed consisting of lightweight 1
inch" plist'c pipe. A 12.T) cm diameter bole was cored thioucch the fltx.il stab in
the appt o.Mnjlt. centre of each wall. '1 he floor slab \ as u full 10 cm thick, and
the stone kner beneath w.is 1 to 8 cm th.ck. A \ertieal pipe was insci ted 'n
each liole arid connected to a central "1 ircl." hcadei . The space between the
pipe and concrete was filled with silicone caulk. The he.idei I an to j i indow,
when* a fh'Mhle duct passed thiough a sheet of plswood mutjiled in a baserient
window fi.ime to 'i centrifugal fan mounted outside lr a box.
The Ir-n pioduced suctions of about 00 Pa in each pipe at the flooi, and
flows and /Vidon ronren 11
-------
7 L/s at G40 pC]/L; parage wall 3 L/s at G70 pCi/L; rear vail 0.2 L/s at
15 pCt/L. Basement radon uas measuied as 6 pCi/L Smoke tests shoued that
ait1 flowed do^n the wall/floor joint except in a region between the [ionl wall
arid garage wall pipes.
The high suction, modeiate radon concentj ations and low airflow* in the
system indicated that the sub-slab fill v*as riot \er.\ permeable, and that much
of the an- i>as being drawn fioin the house lather than fioin the sub-slab fill.
In Maj 1986, tlio radon concentration in the basement i>ith the fan running
ranged from 1 to G pCi/L, a\eiagirig 3.5 pCi/L. When the fan uas turned off,
the concentration roso slo^K oxer 1G liom s ranged belii'wn 110 to 310 pCi/L,
aveiagirig 220 pCi/L over the next 30 hours.
2.?. PHASE 3
In N'o\ember 19SG, detail improvements were made to the s>slcm. The fan
¦was i>jplaced by a large plastic bodied centiifugat fan of higher suction hung
from the joists of a deck al the rear of the house, and tJn.' plywood panel jn the
window uas icplaced with it plexiglas sheet. The wall/floor joint uas caulked
Willi silicone caulking to reduce1 the amount of an withdrawn from the house.
System measurements in December found that condensation wus blocking the
fle.xible duct. Vhen the writer vas diciuied out of the duct, the suctions, flo\> s
and radon concentrations in the pipes uete; side wall 175 Pa, 17 L/s at 2
100 pf"i/L; front wall 175 Pa, 10 L/s at 2 300 pCi/L, garage \ all 210 P.i, 1 L/s
at 1-100 pCi/l, leai vail 185 )'a, 1 L/s at 130 pTi/L. Thesr pie-.si en cool enough to cause i.'Ondunb.ituvi, but > \amiiiation
of the system did not find any sign of ^ate: iicm i nu hi lion.
312
-------
Alpha track detectors were issued in March 1987 to give a long term
measurement of the radon concentration.
An extensive route of entry survey was carried out in April. Enclosures
were taped over si\ sections of the wall/floor joint, the open chimney outlet,
the sill plate in the region of the front porch slab, and over the unconnected
bath and Unlet service entries, and sampled after 24 hours. The radon
concentrations in all these enclosures were less than 25 pCi/L, indicating that
there were no major flows of soil gas into the house in any of the areas
covered by the enclosures.
3. OTHER MEASUREMENTS
Radiation fields in the house and on the site uere measured ^ith a
scintillometer. The field m the basement ranged from 10 to 1C uR/h, averaging
13 uR/h, and on the s'te ranged fiom 8 to 14 uR/h, averaging 11 uR/h. The site
v*as sc e.\tciisi\ el> grades that there v,as no undisturbed soil.
The a\erdj.'c radon concentiation measured b\ alpha-track detectors o\er
the period Match 1987 to Apt i' 1487 vas 5.4 pCi/L in the basement, an-'
3.0 pCi/1. in the living area.
311
-------
MEASUREMENTS SUMMARY FOR HOUSE 25
PYLON AB-5 HOURLY MONITORING
PHASE MITIGATION
SYSTEM
2 Sub-slab
ventilation;
50 L/s
centrifugal fan
TEST STATUS DURING
DATE TEST
05/86 Fan on
Fan of
RADON (pCi/L.)
RANGE MILAN
1-6
110-320
4
220
COMMENTS
o^er -18 hrs
over 30 hrs -
following
16 hr rise to
equilibrium
Sub-slab
ventilation;
150 L/s
centrifugal fan
ual1/floor joint
caulked
12/86 Fan on
5-47
25 o\er 4 days-
condensation
blocking
flexible duct
03/87 Fan on
Fan on
fan off
2-17 9
4-17 8
23-39 30
o\er 88 hrs
o\er 48 hrs
over 41 hrs
after a 5 hr
rise
SYSTEM MEASUREMENTS FOR HOUSE 25
PHASE MITIGATION SYSTEM DATE
Sub-slab \entilation; 05/86
50 L/s ccntrifugal
fan
SYSTEM MEASUREMENTS
COMMENTS
PRESSURE
Pa
90
88
100
100
FLOW
(L/s)
] 5
7
3
0.2
RADON'
(pCi/Li
500
640
670
15
6
Riser
Rlsci
Ri bt'r
Risei
Basement air
Sub-slab \entilation; 12/86
175
17
2
400
Riser A
150 L/s centrifugal
175
10
2
900
Risoi B
fan
240
4
1
400
Ris>ei- C
185
1
J
3 30
n
]' Lf
210
34
At fai->
\: End wa1]
B: Front wa 11
C: Garage wall
D: Rear i«a 11
31 1
-------
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LOW COST REDUCT80N OF INDOOR RADON
FOUNDATION PLAN
Mitigation systom: -£>ue.-^LAf£ sucm&Kj
Data: \Z/Z/&C,
PHASE: FliOAi
HOUSE
NUMBER
315
-------
HOUSE 26
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Short term average \\'L (RP1SU)
Average radon (Tei'tadex)
Radon concentration in \%ater
0.134 WL
0.013 WL
11 pCi/L
5 000 pCi/L
1. DESCRIPTION
This two story detached house uas built in the early !980's on a gentlj
sloping rural site near the top of a mil several miles to the northv%est c.f
Bojertov»n. The walls are coveted with vertical wood siding. Heating is by
electiic baseboards upstairs, supplemented with a small coal stove in '.he
basement.
The basement \%alls are of concrete block, open at the top. The sill plate
partiall.\ covers the voids on each wall. Three ualls are covered with eaith,
the fourth is exposed, and contdi is the door to the single car garage in the
basement. The front porch is supported on a block structure, and is teached
from the basement \ la a door, and is ust-d as a cold rollai. The fioor is of
crushed stone.
The basomsnt flooi >>as pouted in se\eral pours, and has some cracking as
uell as construction joints. The ownoi said that '..here v-ab t complete
pei lineter diam (keeping t\k ) s> stem round nil four wails.
As this housi? had a uceping tile system, the mitigation method chosen for
dciu'is-t^aVo" iias '-eep!"g l1'" 1 eistilatio!':.
li»o dischatge pipes from the v.eepmg til*, system i frc lecated til the
lo\sei p.it I of the siti , traced back to the house, and e ated. I he weeping
tile v.iis found to i un in a 'l.' only around the buried ualls.
On the vest side of the house a uater t: ap of "1 in-h" plastic J ipe r'iiJ
elbm%s Wris nisei ted in the discli. rge pipe. On the c'*?ier side, a sinrla • ii.i',"r
trap uav plar od in the pipe. The house side nf the t-ap uas c- tended
2. ACTION
2.1.
PHASE ?
31 G
-------
vertically to grade level, run back to the house at grade level, and then turned
vertically adjacent to the wall for a fan riser.
The excavation around each trap was filled with plastic popcoi n and
covered with a 5 cm sheet of beadboa>-d for insulation to prevent the water
freezing in the winter. Tine excavations were filled to giade, and sod replaced.
A 50 L/s axial fan was attached to tho riser at the front wall of the house. This
produced 55 Pa suction, 25 L/s flow, with 1 400 pCi/L of radon in the exhaust.
In rr.id ^pril 198G, the radon concentration in the basement with the fan
running ranged from 3 to 11 pt'i/L, a\eragmg 5 pCi/L. Khen the fan was turned
off, concentrations rose rapidlj to vary between 9 to 77 pCi/I , averaging
60 pCi/I.. Turning on the fan dropped concentrations to tho oi iginal range{2 to
8 pCi/U.
Ir: late \pril 1 °SR, 5 cm of concrete was placed over the crushed stone
floor of the cold room to met ease the air tightness of the substructure.
Following this, the radon concentration in the basement with the fan running
ranged from 0.2 to 7 pCi/L, axeraging -1 pCi/L, and rose to range fi om 60 to
191 pC:/L, averaging 100 pCi/L when the fan was turned off. Turning on tho
fan rapidly dropped concentrations to the original range of 0.-1 to 7 pCi/L,
averaging 3 pCi/L over 25 hours.
2.2. PHASE 3
The axial fan was scheduled for replacement by a weather-proof in-line
centi ifugal fan m the fi'!. Over the sun nor of 1986 the owner modified the
house. The garage door into tho basement was remoxed, and replaced b\ a
window. The garage sp *co was turned into a sitting room. A porch roof was
constructed along the front of the house.
tv'ith these changes, en:tent fan location was no longer suitable, for it
disi harged beneath the port h about 1.5 m from the house coiner. The f'iri
! epla*'envnt plan oprrind^d to a fa^i relocat'on plop ! n Oer_emlw>' 193G. the
area was excavated, and a new "1 inch" pipe mn hori. oii'all\ from the trap to
the c-vner of the house, and then \ i-i ticall \ to 50 cm above gride. The new
fan w;is ill,'.-!n d le tho pipe , and the discharge led abo\ o the porch roof by a
"1 inch." pipe.
The new fan produced 210 Pa suction, 50 L/s flow, with radon
concent ration of 110 pCi/l. in the exhaust. In December 19°.6, following the ran
change, the basement radon concentration i anged from 0.! to 1.0 pCi/L,
317
-------
averaging 1 pCi/L. These results were good enough for alpha track detectors to
be issued in December 1986.
In April the owner complained that the fan had become noisy. It kss
replaced. The noisp level had increased, but the performance had not bc« u
affected, and there was no obvious reason for the higher noise.
3. 0T11CR MEASUREMENTS
The radiation fields in and around the house were 4 to 8 uH/h, avorii»t:.g
6 uR/h m the basement; and 5 to 10 uT?/h, a\eraging 7 uR/h over the site.
The a\ erage radon concentration measured Ly alpmi-trark detectors ovor
the period December 1980 to March 1987 i as 2.1 pCi/L the basement,
l.."> pCi/l. in the h\ ing ai^a.
.'H8
-------
MEASUREMENT SUMMARY TOR HOUSE 26
FYUON AB-5 HOURLY MONITORING
PHASE MITIGATION' TEST
SYSTEM DA'lE
2 Drain tile 04/86
venIllation;
50 L/s axial fan
cold room soil 04/86
floor concreted
to increase air
tightness
3 Fail replaced by 12/86
150 L/s
cent f,igal
STATUS DURING RADON (pCi/L)
TEST
Fan on
Fan off
Fan on again.
Fan on
Fan off
Fan on again
Pan on
RANGE MEAN
3-12
9-77
2-8
0.2-7
60-191
0. 1-7
0.1-1.9
5
60
5
4
100
3
COMMENTS
over 48 hrs.
o\er 24 hrs.
over 24 lirs>.
over 40 hrs.
over 30 hrs*.
over 25 hr^.
i"4 hrs.
SYSTEM MEASUREMENTS FOR HOUSE 26
PRASE MITIGATION SYSTEM DA'IT SYSTEM MEASUREMENTS COMMENTS
FRFSSURE FLOW RADON
P& < L/s) (pCi/L)
2 Drain tile 01/86 55 25 1 400 In riser
ventilation; 50 L/s
a\ial fan
3 Fan replaced by 12/86 210 50 110 Trs t isor
150 L/s centrifugal
? 11
-------
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"PEAMUT6"
DETAIL
LOW COST REDUCTION OF 5NDOOR RADON
HOUSE
NUMBER
eie!
FOUNDATION PLAN
Date: Dec.*3&
2 G
Mm
«"i mum
Mitigation system: vvECPiHO"Tile s>u^tic?m
PHASE:RklAL
320
-------
HOLSL 27
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Short term average WL (RPISU)
Heating season average radon ifc^'adex)
Radon concentration in water
0.412 WL
0.008 WL
21 pCi/L
14 -*00 £Ci/L
1. DESCRIPTION
This tvo story house was built m the early 1980's on a leveled site on the
side of a hill several miles to Lhe vest of Hoj ertov r.. The house vails are of
vertical vood siding. Heating is b> electric baseboards upstairs, supplemented by
vood stoves in the basement and upstairs.
The basement vails are of concrete block, open at the top. The sill plate
parliallv covers the voids. There is a large central conci ele block structure in
the basement which contains the stove flues and supports the concrete jipH on
vhich the upstairs stove stands. The vails have 1.0 major ciacks.
The floor is almost completely covered with slo*od materials, but appears to
be in good condition villi no e tacks. There is a construction joinL down Lhe
middle of the slab.
The ov ner said that there vas a complete external drainage system
(seeping tile) around the basement.
2. ACTIO\"
2.1. PHASE 2
As this house had u vccping tile system, the mitigaLion action chosen for
demonstration veepmg tiie ventilation.
The discharge pipe fioin the veepmg nie vas luc.ilcci at d lov part of ! he
site close to the house. The line was traced back to the house and the
junction villi tin: (Jtani pipe excavated. 'L ' tr'ip made frf>m '1 inch"
hghtvei^ht plastic pipe and elbows vas insetted in the discharge pipe. The
house side of the ti ap wtis extended veiticall.- to giade level, and ttin back to
the side vail of the ho is<> foi m fan I .set . The excavation v.is back filled.
The trap vas deep enough {70 cm) that insulation vas not needed to pi'.-vent
freezing.
'} 21
-------
A 50 L/s axial fan ubs attached to the riser. Suction was 35 Pa at 27 L/s,
and the radon concentration in the exhaust was 800 pCi/L.
In April 1986, the radon concentration in the basement when the fan was
off ranged from 20 to 64 pCi/L, averaging 45 pCi/L. When the fan was turned
on, concentrations fell quicklj for 8 hours to range from 3 to 9 pCi/L, averaging
6 pCi/L.
In April 1986, the owner repoi ted that the fan was making tattling noises,
and it was assumed that the bearing had failed. The fan was replaced. When
the old unit was cut off the riser, several snails wer<=> found in tho pipe, and
shell fragments were found on the fan protective screen. The rattling noise
had oeen caused hv snails trapped in the weeping tile crawling toward the light,
and falling into the fan blades. The snails weie removed before the new fan
was installed.
2.2. PHASE 3
IDocembei 1986 the a.\ial fan was replaced bv a permanent p'astic bodied
centrifugal fan. T.ms giiic a svu-tion of 320 Pa at a flow of 40 L/s. The lado:
concentration in the exhaust air was 500 pCi/L. Basement ladon Loncenti allocs
with the new far lunmpg lunged from 1 to 9 pCi/L, averaging 3 pCi/L.
Alpha track dosimetci s weie issued foi final long teun noasui cinorls ii
December 1986.
3. oTiirn ME\srHi:>!r\Ts
The radiation field in the baserpent langed from '¦ to 9 t.R/h, averaging
6 uR/h. Two i.idiu.v dial an craft compasses stoi ed in the basement had fie'ds
of up to 150 nR/h im contact with, t'en boxes. The fields over the site tanged
fion 12 to 25 i-P/h, averaging 16 uR/h.
The average radon concentration measuied by alph.i-t* ar k deteeti ¦¦ s
the pe:"fn' December 198G to Mai eh 1987 was 3.8 p('i/L in t h •' basement, and
2.2 pr./L l- '.he living ai e.i.
-------
MEASUREMENTS SUMMARY i-OR HOUSE 27
PYLON' AB-5 HOURLY MONITORING
PHASE MITIGATION TEST
SYSTEM DATE
2 Drain tile 01/86
ventilation;
50 L/s axial fan
3 Axial replaced 12/86
by 150 L/s
centri filial
STATUS DURING RADON (pCi/L)
TEST
Fan off
Fan on
Fan on
RANGE MEAN
20-64 -15
3-9 6
1-9
COMMENTS
over 39 hrs
o\er 38 hrs
over *10 hrs
SYSTEM MEASUREMENTS FOR HOUSE 27
HIASE MITIGATION' SYSTEM DATE SYSTEM MEASUREMENTS COMMENTS
PRESSURE FLO^V RADON
Pa (L/s) (pCi/L)
2 Drain tile 04/86 35 27 800 In riser
\entilation; 50 L/s
axial fan
3 Axial replaciid b\ 12/8S 325 100 500
150 L/s centrifugal
In riser
323
-------
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LOW COST REDUCTBON OF INDOOR RADON
HOUSE
NUMBER
¦
FOUNDATION PLAN
Da «©:p&c.^6
27
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Mitigation syotam: v/cEPws TILE. f.UC-Ttou
PHASE-.r/SAL.
324
-------
HOUSE 28
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Short term average WL (RP1SL')
Heating season average radon (Terradex)
Radon concentration in water
0.155 WL
0.118 WL
21 pCi/L
N/A
1. DESCRIPTION
This two stoi y house with attached gaiage was built in the late 1970's at
the fool of a gently sloping site in a rural subdivision on the top of d lull a few
miles west of 01e,>. The low or part of the front wall is bi ick, the other walls
are of siding. Heating is by oil-fired forced warm air with an electronic air
cleaner, supplemented b.\ basement arid main-floor fireplaces.
The basement walls are of concrete block, and most of the area is finished.
There are water marks on the visible portions of the walls. The floor slab iiaa
two riacks visible, and there is an open sump with sump pump in the unfinished
part of the basement.
The ow ner said that there was a complete weeping tile stein with an
external dram all around the house, even on the garage wall. He did not know-
to what the sump uas connected. The site. had been regraded several times to
reduce water leakage in the block walls.
2. ACTION
2.1. PI1ASL 2
As this house had a weeping tile sj stem the initial mitigation action chosei"i
for demonstration was weeping tile ventila-tion.
"he wcf-ping tile disthaige pipe e\il could not be found on the site. In fact
the gentle slope of the land m the ai ea irade it impossible fo: a main at foeting
level to reach the suiface within 15 m of the house, well off the site. I'-e
conclusion was that the tile, ;f piesent, probablv dtaini'd to a bulled on-site
soakawa\ pit. The water stains on the walls suggested that Hie dra.i tile
was nil v rrv effective. Rather Ulan disturb the diamagi sv stein bv digging :u d
perhaps aggi av ate watei pi obh-ir.s, the deeisioti was made to pursue 'iMiei
mitigation avenues.
'12 '
-------
The sump offered a potentially easy route to ventilate the sub-slab space.
The mitigation method selected for an initial demonstration was therefore sump
ventilation.
A submerged suinp pomp with a "2 inch" plastic discharge line was in the
sump. Screw anchois were placed in the concrete around the sump and a
plywood cover, split to pass round the discharge line, uas sciewed and caulked
into place. \ "4 inch" lightweight plastic ventilation pipe was attached to the
cover with a toilet fl'ingo. The other end of the pipe lan to ;ibo\e gracie and
out through the block wall to a 50 L./s a\ial fan mounted in a "6 to -1 inch"
reducer attached to the pipe. A second capped pipe stub was attached to the
co\ei to piovide access to the sump for drainage-.
In April 1SSG, the radon concentration in llu" basement with the sump fan
in operation ranged from 13 to 30 pCi/L, a- eraging 20 pCi/l.. Investigation
found the fan gave 68 Pa suction at 6.5 L/s, but the i adon concentiation in the
exhaust was only 57 pCi/L., at a lime when the basement concentration was
20 pCi/L. These lesults indicated that the sump did not effectively t^ccess the
sub-slab space.
2.2. PHASC 3
In November 1986, the radon concenti ation in the basement with the sump
v enti'ptiori far. running i anged from 10 to 68 pCi/L, aveiaging 22 pCi/L. Water
was leaking into the basement thsough the block wnll in the sump area, and was
not able to diain into the sump because of the sciewed ami caulked sump cove:.
As Hie system was ineffective and was inconveniencing the home owner, it wr>s
removed in December.
As this house li.id a finished basement and relatively low i adon levels, the
alternative mitigation method selected for demonstration in this house \ as
increased ventilation by an air to air heat e\changer had installed a number of
1IR\ 's for r.idmi eontiol. \s the basement was finished and used e.\tensi\ elv,
he i''cc>r;n:iOi:ded t 1; isement flood system to reduce- ; .idon levels both in the
basement and upstairs. The unit was installed in tie storage u:ca, exhiusled
from there, and discharged fit.sh nr into the fnnulv rouii at ~H L./s on high a.id
f>3 l./s on low fan <*peed.
!ji I'ebi u.iry 1087, r'i'lon conr cut rations in the basement with the HiJV
running on high ra-iged ftmii 7 (o 17 pCi/L, averaging ?0 pCi/L. Mien the MIIV
32G
-------
was turned off, radon concentrations ranged from lu to 21 pCi/L, averaging
10 pCi/L.
Alpha track detectors were issued in February 1987 to provide a long term
measurement of the average radon concentration.
Another set of measurements were made in February to check the effect of
the HRV on internal air circulation. Measurements uere made in the family
room with the door to the unfinished area closed to isolate the fresh ai:
delivery area from the exhaust area, and upt lairs in the sitting room. With the
HR\ on high, the radon concentration in the fanulj room ranged from 7 to
12 pCi/L, averaging 9 pCi/L, comparable to the whoi--' basement value measured
on the pre\ icius run. Simultaneously the upstairs concentration ranged from 5
to 10 pCi/L , averaging 7 pCi/L. When the HN\ uas turned off and after a delaj
of seven hours, the family room radon concentration langid from 10 to
22 pCi/Ij, averaging 16 pCi/L.. At the same time the upstairs concentration
ranged from 5 to 13 pCi/L, averaging 9 pCi/L. The effect of the HR\ appeared
to be confined to the basement, for halving the concentration there made onlj
a slight reduction ni the upstairs radon concentrations.
3. OTHER NirASliRJ£NlKXTS
The radiation field in the house ranged fiom 'I to 8 uR/h, averaging
6 uH/h. The field over the site ranged from -1 to 10 u.V/h, averaging 7 uR/h.
Th" average radon concemratiou measured bv alpha-track detectors over
the period February 1987 to -\pril 1987 \%as 2.1 pCi/L in the basement, and
5.3 pCi/L in the h\ lrg area.
32"
-------
MEASUREMENTS SUMMARY FOR HOUSE 28
PYLON AB-5 HOURLY MONITORING
PHASE
MITIGATION
SYSTEM
TEST
DATE
ST All's DURING RADON (pCi/L)
Stnup \enti lation 01/86
50 L/s axial fan
Heat recovery
ventilation;
100 L/s unit
11/86
02/87
02/87
TEST
Fan on
Fan on
On-high
Off
On-hi«h
On-high
Off
Off
RAVTi: MEAN
13-30 20
10-G8 22
7-17 10
10-21 16
7-12 9
5-10 7
10-22 16
5-13 9
COMMENTS
o\er -1 days
over I days
over 37 hrs.
over -52 his.
over 10 hrs.
o\er 10 his
upstairs
o\ er- -J 7 hrs.
ov'-r 47 hrs.
upstairs
SYSTEM MEASUREMENTS POli HOUSE 28
PHASE
MITIGATION S\STEM DATE
SVSTEM MEASURIMEYI'S
PRESSURE FLOU RADOv
Pa (L/s) (pCi/L)
COMMENTS
Sump ventilation; 0-1/86
50 L/t> a-\'i al
f»8
57 Fan on - rise
pip.-
20 Tan on -
basement air
H(jat I!ecov-ei.v
\en t jlation;
100 L/s unit
02/87
C3
78
low speed -
fiesh aii
tl:scliai rfe
high s|x_'"d
fresh nil
d i srh.u ge
32S
-------
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cover;
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TAWC
LOW COST REDUCTION OF INDOOR RADON
FOUNDATJON PLAN
COMUEC?CtAL
Mitigation system: ce^vERy vemtilatcr
Date: mov< &C-
PHASE:PiV!AV.
MOUSE
NUMBER
28
329
-------
HOUSE 2D
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (husnetz)
Short term a\ eiage WL (RPISU!
Heating season a\erage radon (lerradex)
Radon concentration in water
61 pCi/L
23 000 pCi/L
0.580 KL
0.032 hi.
1. DESCRIPTION
This two-stoiy side-split house with attached garage was built in the late
1970's on a level site neat the ten of a i ldge a fev miles west of Uie>. I he
lowei half of the house walls ure of brick, the upper half of siding. 'Heating is
b;. an oil-fireJ foic.d an s\stem with un electronic air cleaner. Thexe is an
upstairs fireplace in the family room.
The basement walls are of concrete bloi;k painted with waterproof paint.
There is a dirt flo>*>r crm%] space with unpainted block vails beneath the family
room. The block walls are open at the top, and the void3 on the front and back
walls fire partially roncealed b.> the sill plate.
The flooi is in fan condition with some clacking iind there is an open sump
with wati-r in it in one corner of the biser:ent. Thei e weie openings m the
plastic sump liner, but the ownei did not know if the;, connected to sub-s;ab
drains.
2. ACTION
As this house had a sump, the first irutigati\e action chosen foi
demons! ration v. as sump \ en Illation. The luge area of exposed soil m ;ho
ciawl sp'ti.e also required ti eatnicut, and tne second action chosen f'>i
demonst i ation uas soil ro\eiing plus \ ontilaticn.
'I he sump held a submci t;ed sump pump with a "'2. inch" plastic discha.-^e
line. Sci^u aucl'oi s we>e placed m tne conci«te mound the sump, f in.g of
f .pa'idmg uifth.u'C fn-ipi w.is pv.t lourid the top of the si.mp as a gasl.o:. \
p! ¦ wood kai.1, split to p iss i ciind I'lt' d,s>'. ha/ge hn';, \» is s._:ew<-u >n place. \
"1 inch- hghtwe'ght plastic pipt was attached to the cover with a toilet fa
the oth' J "i'k! of 11.e pipe iar to a uearb> window opening, -tnd was c onri.""j'.eJ
2.1.
PHASE 2
'<.(0
-------
by flexible hose to a 50 L/s axial fan mounted oil a plywood shoot in the
opening. A capped "t inch" pipe stub was attached to the co\"or to pro\ ide
access to the sump for drainage.
¦\ 1.5 by 3 m loop of perforated "1 inch" lights^ight plastic pipe was placed
on the open soil in the crawl space, and was connected to "I inch" pipe that ran
to a second 50 L/s a\ial fan mounted on pl;< wood in the window opening. The
open soil in the crawlspaee \^as covered with Uo !a\ers of 6 mil pol\eth> lene
sheet. The edges of tlie sheet were fastened to the block basement walls by
"1 by 3 inch" wooden furring strips, and all joints. were covered with asphaltic
caulk.
In Apiil 1986, with both the sump and craw Ispace fans on, radon
concentrations in the bastrietU ranged fro in 5 to 22 pCi/L, averaging la pCi/L.
Investigation found that the sump fan ujs developing GO Pa suction, at a
flow of 8 L/s, and a radon concentration of 1 000 pCi/L. The crawl space fan
developed 20 l\a at a flow 25 l./s, with a i adon concentration of 1G pCi/I . The
basement air concentration Mb 12 pCi/L at the ti.r.e and air drawn froi,.
floor diain showed a concentration of 17 pCi/L. Smoke testing of the open
blocks around the opening to the craw 1-space gave possible indications of flov
into some and flow out of others, with no appai ent pattern.
The similar radon concentrations in the baseirent air and the crawls pace
soil e\haust air indicated that most of the soil e\hai'«l air was house air thet
had leaked beneath the cover through the cracks ami openings in the blot!,
walls. It also suggested th.it the ciawlspace soil was not the major radon supply
route.
This was tested directly in Max 198G, when the crawlspico f in was tinned
off. With both fans running, the radon concenti alien vai »ed from 1 to 21 pCi/I,
averaging 15 pCi/L. \\hen the craw! space fan was tinned off, concentrations
\. h: i^d from 2 to •! 1 pCs/L, j'.x ei pgiog 20 pri/L. Uith both fans off.
concentrations langed fiom 7 to 90 pCi/i , with marked diurnal >-\iling, and
averaged 35 pCi/L.
In Juiv 1986 with lid fans on and,the sump open so that a dehumaiif.i
could dram into it, th< basement cimttnlra' ion tanged f.'om 20 to 1!1 pOi/L,
will, mai ked diuinal cwJ'ng, and averaged 90 p«."i/L.
2.2. pii-xsi: 3
311
-------
Ill January 1987 the two existing fans were removed, the sump and ciawl
space suction lines joined through a "T" connection and u large plastic bodied
in-line fan installed to increase the exhaust suction.
Kith the ne\> fan operating, radon concentrations ranged from 1 to 3 pC)/l.,
a\eraging 2 pCi/L. When the fan was turned off the radon concentrations
ranged fi-om 19 to 43 pCi/L, averaging 30 pCi/L. The suction in the sump was
120 Pa, with a flow of 15 l./s at 600 pCi/L. The radon concentration in the air
from the erawlspace was 13 pCi/L a suction of 93 Pa and a flow of CO L/s.
Alpha track detectors were issued in Febiuary 198T lo provide a long term
estimate of the radon concentration.
3. OTHFR MEASUREMENTS
The radiation fields in and aiound the house were 8 to 9 uR/h in the crawl
space, and 5 ts? 7 uR/h in the basement over most of the slab, but increased to
12 to 14 uR/h in the area of the sump, and 10 to 13 neai the well pressuie
t°nk. The field outside ranged from 8 to 14 uR/h, averaging 12 uR/h.
The average radon concentration measured by alpha-track detectors o\ er
the period !\;bruar> 1987 to April 1987 was 1.9 pCi/L in the basement, and
1.4 pCi/L tn the li\ mg ai ea.
-------
MEASUREMENTS SUMMARY FOR HOUSE 29
PYLON AB-5 HOURLY MONITORING
FHASE MITIGATION' TEST
SYSTEM DATE
2 Sump + craul 04/86
space
ventilation; tuo
50 L/s axial
fans
05/86
07/86
3 Suction lines 01/87
teed together;
fans replaced by
150 L/s
centri fugal
SYSTEM MEASUREMENTS KIR HOUSE 29
I-UVSE
MITIUVHON SNSTLM
DATE
SYSTEM MEASUREM
ENTS
COMMENTS
pressuuf n.ou
RADON
I-a (L/^)
(pCr/L)
2
Sump +craKl-bp'ico
01/86
GO S
1 000
Si.mp fan line
\ erit11 a11 oii j tv*o
' r,
Ci 3> 1 ¦ j p-
50 L/s umhIs on
11 no
12
li<\seinerit .xii
17
Flooi ill .un
3
Lines teed; ffins
02/87
120 15
GOO
Sump line
replaced by 150 L/s
yj go
U
Ci l-spj.ie
centrix1
lino
333
STATUS 1 HIRING RADON (pCi/L) COTMI",NTS
TEST RANGE MEAN
Sunip and craul 5-22 15 o\er 46 hrs.
space fans on.
Both fans on -1-21 15 o\er -18 hrs.
Crawl off/sump 2-1-1 20 over 42 hrs.
on
Crawl olT/sump 7-90 35 oxer 4 da\s
off
Both off/sump 2C-1 1-5 90 o\er 4 dajs
open
Fan on 1-3 2 over 47 hrs.
Fan off 19-43 30 oxer 37 hrs.
-------
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FOUNDATION PLAN
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Mitigation system: akjC> SUmp cljctioW
Dato: »JAM. ©7
PHASE:HWAL
HOUSE
NUMBER
29
334
-------
HOUSE 30
PENNSYLVANIA DER MEASl REMCNTS
Working Level grab samples average (Kusnetz)
Heating season average radon (Tersade.x)
Radon concentration in hater
0.137 WL
17 pCi/L
266 000 pCi/L
1. DESCRIPTION
This single storj house has built m the late 1970's on a gently sloping
rural site near the foot of n steep hill several miles south of Oley. The halls
are covered \%ith siding, and heating is by electric baseboard units. The ovv iier
has added an oil fired boiler with hot hater con\ectors. The basement walls are
of concrete blocK, and there is an external entrance into the basement.
2. ACTION
2.1. PHASE 2
This house hed the highest concentration of radon in hater of all the
houses in the Reading Piong area tested by the DER, and it has probable that
most of the radon in the house air came from the hater. The mitigation
measure selected foi demonstration was removal of water borne radon by
adsorpt.cn on activated charcoal.
Preliminary radon concentration measurements in the basement dining Mj\
1986 found that iho baseline radon concentration has iri the legion of 3 to
5 pCi/L, but there here peaks to 67, 68, 122, 210 pCi/L associated in time hith
operation of the hashing machine, and in size \%ith the amount of i»;iter useo..
This has consistent \»ith the water being the major tadou mule of entrj .
A commercial chascoal adsorption unit w,is ordered fiom a specialist
coil nan.v in Maine, hiio used 170
cm high fibei glass renfo, p'astic ian'\, loulaiuinir r>o L of charcoal. Ml
piping has connected to a b-ick-flush \ al* mounted or. lop of the tank.
The s\sterp has effective. -\ test m August 198C found that hates'
toncn! i atio>i«- here reduced from 178 000 to 1 100 pCi/l (Tl. 1% lemoval) by
passage through the un't. Radon concentrations in th<- basement langed fiom 3
to 0 pCi/L, avoiagini; " pCi/L, a:ici shewed no signs of \\u latum hith .,so.
-------
The radon removed from the uater is stored on the charcoul ir. t!i«_ tj.-W.
and during its decay emits gamma rajs. The basement radiation field froin t!ie
tank was estimated v»ith a scintillation mete- at 10 000 uR/h mi contact,
1 100 uR/h at 60 cm, and -12 uR/h at 3.5 in ftom the tank. In the child's
bedroom upstairs abo\ e the tank, readings \ aricd from 25 uR/h duectly abo\e
the tank, to 55 uR/h near the bed, to 93 uR/h on the floor it the centie of the
room. For corapnnwn, the buckgr.-. and radiation o> er the ground outside the
house i.as 10 uR/h, and had been about G uR/h in t .e basement before the unit
uas installed.
Scintillation inetei a do nut estimate ladiation fields reliably if the .'adialioii
spectrum dtffets gieatly fiom thai used to calibrate the instrument. To pre 'de
a bettoi estimate of exposure rate, the l'enns\ lvania DER placed TLD dosimete:s
in contact with the tank, al GO cm and 3.5 m fioin the tank. The average
exposuie rates over a 29 da> period \>ere 1G 700 uR/h on contact, 320 ull/h at
GO cm, and -51 uR/h Si ^.5 m. These results were close to those estimated by
the scintillometer.
The ousters ueie pleased that the radon lev. el :n the uater had been
reduced, but wci e concerned about 'he inn ease in ganinn radiation, especially in
the child's bedroom. They mo\ ed the child into their o^'i bedroom v* hen. tlie
field \»as lcv>er.
2.2. Phase 3
A-, moHnurf vhile permanent shielding i.js designed, the lark
wis trapped \»ith 1.6 mm (1/16 inch) lead sheet. The fust la;>er halved tiic-
meter reading, but the second la;, er produced only a furthei 20% reduction, "our
additional !u-ers of lead \> rapped a:ound the meter uere ".eeded to reduce the
reading at to backgioutid (13 wR/h), suggesting that 10 mm of lead \%ould b,_-
needed fo'* complete shielding.
Three add ition.-u of lend .she el nfic placed on I he op of i lie lank
and trapped siound Lhe back-flush ial\e to i educe the \ •ji t icril component • f
the lailiaiion that leathed the child's bedrc>oni. TI • > • field i>js i educe I t _•
In uli/h Jirecti.\ o\ci the lank, and to 25 uK/h (50% .tbo\e background) <:t :he
bed by this shielding.
The rac'. lotion measiu einents suggested that 1 'in of lcvd shielding uould be
neede
-------
review of the options led to the conclusion that concrete would be a better
material than loud for a permnnoit shield. Si\ cm of concrete would pro\ ide
about the same shielding as 1 cm of lead, and this thickness could be provided
convenientlv by standai d concrete blocks, which have u minimum total uali
thickness of GO mm. A concrete block enclosure round the tank, topped with
one or two concrete pavers or patio blocks seemed a rost effective alternative
more in keeping with the general skills and experience of the building trades.
In \'nv ember 1986, the lead was removed, and the lank was moved slightlv
so that standard concrete blocks vould fit around it and touch the basement wal!
without cutting blocks. A rectangular structure 60 cm by 60 cm by 160 cm high
lias built round the lank of "4 inch" concrete blocks. Larger blocks would not
have giv en mme shielding, for thej do not hnve thicker ualls, just la: ger \oidr..
The blocks uero mortared together, and the structure uas secured to the uall
Viith metal stiapping to ensure stability. The top of the structure uns covered
with "2 inch" .solid concrete pavers, cut to fit round the water line.
Continuous radon measurements were made upstairs uhile this uork was in
progress. While the unit was on line, baths and showers ueie taken, the
dishuashvr run, ar.d radon concentrations varied between 0 and 2.6 pCi/L,
averaging l.~> pCi/L. The unit uas b\ passed for two hourt. uhile it \»as moved
by the workmen. During this period, a bath was taken with unticated water,
and the upstpirs radon concentration peaked to 11 pCi/I. at the same ti.r.e and
retui tied to normal v%ithiu a hours. Rasement concentrations ptevious to the
ragged fr<-"n -1 In 6 pCi/L.. avet aging 5 pCi/I, and shouing no signs of
variation v.ith \ ater usage.
The conci'i'li.' shielding reduced the radiation field at 3.5 m to 11 uK/h, and
the field in the bedroom to 15 ulf/h ovor the tank, and 11 uR/h at the bed.
The muxiinuni field m contact \\ith the concrete shield was COD ulwh and
background indiation in the basement uas measuied at 6 uR/h.
Mpha ti ark delectoi s \%r»rt> issued in L)ei"mbe: 19Rfi to iletei mine the long
term nv ei age radon coiicentr.it'nri.
Ai i angei.ien's uejo made to ihouiUji the unit fci laduu removal efficient^
and to check fot bactei lal giouth on a monthly L.isis. Vhen the first lest v. is
made in Jaiuiiirj 1087, the maximum i*idi»tion field in contact \\ith the concii.te
had incieased lo 1 300 uR/li, indicating that the amount uf tadon s-'UmJ m tiie
tank had doubled. 'I his piobablj was due to inci eusud u.Uei use, foi theie s.it-
337
-------
a new baby in the house. The radon concentration in the untieated water was
240 000 pCi/L, and was 12 000 pCi/L iji the treated water, so the xeinovu!
efficiency had decreased to 9fi%.
This increase in source term made the existing shielding marginal. As u
first step to increase the shielding, the lead sheet that Imd been iemo\ed from
the tank was hung on the inner side of the blocks. This reduced the radiation
field by about 20%, but additional shielding was still needed.
The effective thickness of the blocks could be doubled lo 120 mm concrete
equnalent by filling the \oids with sand. This was tiled, but the sand a\a.lable
fiorr. the local builders' supply had been stored outside, and was too damp to
flow through the voidb, which vere pin tially obstructed by the mortar between
the blocks. The sand was therefore placed in the space between the innci face
of the blocks and the tank, this provided from 8 to 20 on of sand. The
maximum field in contact with the shielding was reduced to 320 uR/h, ftom
1 200 uR/h. The radiation field at 3.5 m whs reduced to 11 uR/h from 2a uR/h.
\hout two weeks later, in early tebruarj, the owner imported wutei was
leaking from the bottom of the shielding walls around the carbon unit onto the
basement floor. Th<-' paving stones on top of the un:t were removed, r.nd sand
lemosed to expose the pk-mbmcj and the top of thi< tank'. No leaks were visible
in the tank or piping, but the sand wps very dan-p and there was condensation
071 thp water lines inside the shield. The top of the shield was left open foi a
few days, the sand di ir>d up and the leal.age sfopp»d. 't is bche\ed lh~;t w"'c*i
w'hs into the sand, which had been stored outside, and had melted,
saturating the smd and causing the leakage.
When the s\ stein was reasjembled lh>' radi itior. fields were renn-asi:i cct.
1 hf- imiMiiR-m field m cnnt.-ct with the concrete shield was 213 uR/h :mj the
fu Id at C.'i m i.a-. 9 u'Z/h. Clearly there had b>vii a rodi.ct ior: m son.1 ' e
.siii.ngth. The rt'id.j.'i ',0!V:sr!l! .".tion m the w tier ^ f>, i»r mured at 2J-S 000
so this was nr>*. due In a deft ease in redo." • oncent i ation. The !.*•. Inn
rni'ffnt l 'it ion m th'- I reded water \ us 3 000 pC'i/1 . n i •-* inf >\ : 11 efficient;*. i,r
W.7%.
The radon tnm "nti jtmns in tin- w iter wore rniMMnv.-l m -*r¦ i-nit, foi a i eirov.'il efficiency
of 07%.
338
-------
Gamma monitoring during the visits to collect the water samples found that
the radiation field was fairly constant in time. The maximum fields, o.i contact
with the shielding \%ere 230 uR/h in March, and 24T uR/h in June 1987. The
corresponding values at 3.5 in ueie 11 and 9 uR/h, and in the bedroom above
the tank 8 and 7 uR/h.
The DER placed TLD dosimeters in th'> house, and found the average field
from March to June 1987 to be 12 uR/h at 3.5 m, u.id a maximum of 16 uR/h in
the bedroom.
The removc.il efficiency of the charcoal \>as high, but appai entlv \ jnifl \%ith
timo from 95% to 99.4% removal. The performance \<.as not as good as claimed
bv the manufacturer (99%-»). The volume of water used i'id\ have been too high
for 55 L of chat coal to achieve that level of pet foi inance.
The combination of high \.at«?i use and high ladnn concentrations m t!u
water lead to the storage of niicro-Cur>e.s of radon :n the tank, with
correspondingly increased radiation fields i-i the house. Shielding against these
fields is not a trivial task. The installed shielding is adequate, but if the \ ater
should consislenll\ reach the concentration of 250 eOO pCi/L imtiallv measuied,
coupled with high wa'er use, it wcnld be onl.v just acceptable.
3. OTHKR MEASlRTMFVTS
The radiation field in the house prior to installation of the ,ai bun unit
ranged fiom fi to 12 uR/h, and averaged 8 uR/h. The highest field was found in
the Vicii.il> of the \v clJ piessuie tank. The fieM over the -i'.c langed fion 7
to 13 uR/h, averaging 10 uR/h.
The average i adon concenti atior. measuied b.v alpha-truck detectoi s ov ei
the period December 198G to March 1987 \ as 3.0 pCi/L in the basement, and
1.3 pCi/!. in Ihe living aiea.
339
-------
ME-VSUirMEVI'S SUMMARY ION HOL'Sfc 30
OLON \B-5 HOURLY TORINO
PHASE MIT! CAT ION TEST STATLS DUTilNG KADON KESl'LT^
SNSTIM LUTE TEST liAN'GE MEAN
co^nirci's
Pr em i t l gci 11 rui
radon
ndsorpt ion
55 I. ch ircxul
urn t
05/86
11 /86
N/. \
Oti 1; re
'h o liour:
1 i i>.e
off
0. 2-210
4-6
0-2.7
11
o\ ei 1 dn\ s
baseline 3-
5 pC!/L -
peaks of 67 ,
G8, 122 and
210 pCi/L
o\ci' 3 i hrs
o\ i j PC lits I
peak -
lint i eated
bathwater
U: Upstairs
SYSTEM MEASUREMENTS FOR HOUSE 30
IlIASi' MITTC Y! iO\' SYSTD1 DATE R\DO\ J \! W-YTCK (PCi/L)
BEFWF \FTEK KEIX Ci'IO\ COMMENTS
%
2 I^uJon dflsoiptum 55 L 08/86 178 700 1 100 00.-i
chan o tin 11
3 l&ulo?" aibsorptjon 55 1 01/^7 2-10 000 12 000 95
chai-cnal uni! +
nonoivt e M ock
sh icldmg
3 Radon fiJsorplion 55 L 02/87 236 000 3 000 98.3
chai-noal unit. +
saii"]f:!li I ! !> ir' lnif»l
( one r< -t r; 'i1 < k" '»
sh i f ' (i 1 r -_j
' 03/rj7 no ooo 3 500 -j7
310
-------
Cm ME.ASUREMI3.TS * FOR HOUSE 30
phase
MITIGATION SYSTEM DATE
Water adsorption
55 L/a charcoal iuut
MEASUREMENT
LOCATION
CWl\ FIELD
(uR/h)
08/86
On top tank
Distance
f rom
top
of
tank
0 cm
20 cm
40 cin
60 cm
80 cm
100 cm
120 cm
500
1 700
f> 100
9 GOO
8 600
4 '100
1 800
500
COMMENTS
On contact
On contact
On contact
On contact
On contact
On contact
Oti contact
On contact
Basement
60 cm from unit
2 m from unit
House Jack 3.5 m
Oppos ite (ba<.k wal 1)
Ch j mne\
Dn\ewa\ vail
065
132
12
19
19
9
L'i>i>ta i rs Ch lid's Room
Aljove tank 25
Centre 54
Toychest. 56
Bed 50
!)oon>ay 25
Contte 93
On floor
Hi tchen
Dri veuaj
Adjacent so.i 1
i
13
09/86 Tank - contact 1G 700
10/86 - 100 cm 320
-3.5m 11
29 day TUJ
DER
Iviter adsorption
55 L/<^ charcoal unit
plus tt=mt lead
sOi icld mi;
10/86 Riseinont
House JacK 3 . :i rn
Ui'-i tins
A'io\e ta".k i.'tapjvxi
in tiso sheets
5u Without lend
25 1 lead sheet
(1.6 i'im)
19 2 sheets
15 3 sheets
9 6 sheets
32 \'o le'id en top
22 1 1 e-id sheet
on top
17 2-^ sheets
folded
311
-------
GA>I>LA MEASUREMENTS* FOR HOLSE 30
PHASK
mitigation; systdi date
Water adsorpt i on
55 l./s charcoal unit
plus temporary lead
shielding
Water- adsorpt ion
55 L/s charcoaL unit
p]us concrete block
shielding
10/8R
MEAS:.W?1ENT
LOCVTIOV
Un^talrs
Ch i Ids room
Li \irig. room
Outside
12/8G Chi Ids Room
Over tank
Bed
Centre
Doorvav
ga>m\ field
{.iR/h) COMMENTS
2-3 shoots
25 folded
7
11
10
1 !
20 On floor
11
livuvg rooai
Buscipont
Uri\ uall
House Jack 3."
6
14
Katei adsorpt. i on
55 L./s charcoal »in:t
plus lead-lined
amn i:l.e block
shield iriK
tai^r ridsorpi : or»
55 l./s charcoal unit
plus sand-fi] led
load-lined concrete
block shielding
01/87
01/37
oi/s:
(louse Jack 3.5 ra
Dri \ci-tiy u-all
House Jack 3.5 m
House Jack 3 5 ir.
at I m
24
6
22
! 1
50
C2/87 House Jack 3.5 m
House Jack 3.5 n
11
rhiia's rvHti-op-n
0\ e r t
IJoo n>u\
Cen* re
i
5
G
Chi floor
Kj leiien
06/87 5Vii.cmoi>t
House Jack 3.5 m
L)i ive;vay will
1 1
O
f,
312
-------
GAMMA MEASUREMENTS» FOR HOUSE 30 (CONT)
PHASF MITIGATION S\STEM D\TE MEASUREMENT GAMMA FIEIH
LOCVriON (uR/h) COMMENTS
06/8'/ House JacK" 3.5 in 12 102 day TLD
DER
Child's Bedroom 1C 102 day TLD by
DER
t At a height of 1 unless othoi.viso stated.
G \>M\ MEASt RhMl "NTS
[\ ^ONT.VT WITH Sill 1 I.DING
101? HOUSE 30
DAT!" W BLOCK 1 BIjOTK 2 ULjOC.1v 3 BLOCK 1 BLOCK 5 BLOCK 6
Water Adsorption 55 L/s rhireonl unit plus concrete blocK s»hieldi-i«
12/86 57 133 290 490 GOO GOO 3G1
01/87 115 25-1 57-1 960 1 216 1 330 811
01/87 113 227 5G2 867 1 1G0 I 208 762
Water adsorption 55 L/s charo-il unit plu^ 1«. lined concrete blo<_k shielding
01/87 177 468 730 973 970 643
Walet ;ai i^orpi.: on 55 L/s chaixu. i] i_ui it plus s.'uid-fi 1 led ! cud-1 i:ie-i concrt.-t e
block shielding
0!/?7 23 33 105 210 320 30 3 173
02.'87 27 85 180 215 225 P5
03/87 13 30 80 160 230 215 120
OG/87 lo 33 82 1C5 217 237 1 13
06/87 17* 111* lilt l||t
~ I)!J{ 102 div Ti D mf-f-ui enicnts cite mmki'd \ itl> .'in asterisk.
( n
-------
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V/lTri 5AMP.
LOW COST REDUCTION OF ONDOOR RADON
HOUSE
NUMBER
111
FOUNDATION PLAN
Date: n
JO
..... .. . CWACC^L A:^::cr!OM
Mitigation system: \.«-'/CJ.MAn,r~m
PHASE: FiMAL
^44
-------
HOLsr: 3i
PENNS\ L\ \\'IA DFR n XSL'RF^IEKTS
Working Lex el gi ab samples (Kusnet::) 1.881"1 KL
Heating* season short term aveiage WL (RP1SI ) 0.f>09 UL
Heating season average (lerradex) 85 pCi/L
Radon concentration m water N'/A
1. DESCRIPTION
This single stoi y house with attached garage was built in the late 1930's on
a sloping rural site on the s.de of a : id^e a few mile;, west of SJoj ertow ri. The
house walls are of brick. Heating is by oil fired hot Writer c.-culated thiough
radiatois, supplemented by a wood slo\o in the basement.
The unfinished basement has hollow concrete block w.-dls which are (.losed
at the top with cap-blocks. Theie is s» small root cellar w llh a wooden dooi at
one end of the basement, and an exterior entrance door at the othei end. iise
floor of this loom is co\ erud with a concrete slab. There ai e no cracks :n the
walls. The rice:- slab is poured tight against the walls, but it v as placed in
till ee pours with two construction joints up to G mm wide. The floor slab is
penetrated b\ cosset ete filled steel columns whii.h suppoit the isain steel beam
and the walls a: e penetiated by a well watei line and a tanilai > line to a septic
tank.
The ownei reported that the concrete slab is pei.red on a good ba is of
crushed rock, but that there was no weeping tile d'-ain lound the pel lme m of
the house.
ACTION
O * Tl< T \ O p 1
•>* I • I 1 * \ > i„ J
This house had been one of the candidate houses. !'oi Phase !. It had been
c nnsu'ei i d as a dei'io'T-.ti at i«'>ii house fos wjl! \ e..til'ition, but had not been
.^elc-f.! because the cap-block** v.,, »n-> weie an unusual featuie for the
-uea. P'le i out cell.u .it thai time w is a compla >'t ;ng faetoi, foi it w is laipnul
then, wills a Ho >r of (rushed stone. The owner had pa\ ed tin flooi in IPSO, but
the i j'I'jii le*ei had h< en uis iffeoted.
" i:>
-------
2.2. rHASK 3
By this stage of the program there was confidence that the multipoint sub-
blab ventilation sj stem with high suction fan could deal with holloa concrete
block walls particularly if there was a sub-slab layer o"" ciushed lock. The
mitigation method chosen for demonstration at this site was subslab ventilation.
A s>i.\-;nch TVC pipe was run along the centr.al beam main duct of the
subslab ventilation system and si\ -1-inch down pipes of PVC were installed Ir.
perimeter holes cored 111 the slab, om; at each end wall and two at each long
wall. Suction wab applied to the main duct by an external plastic bodied
centiifugal exhaust fan.
The suction al each subslab entr> point was 2j0 Pa. Flows .and radp.;
concentrations in each pipe wcio; end wall 2 L/s at 1 -100 pCi/L; rear wall 5 L/s
at 1 400 pCi/I., rear wall 0.5 L/s at 570 pCi/L; garage wall 12 L/s at I
GOO pCi/L; front wall 3 l./s at 770 pCi/L; and fiont wall 3 L/s at 2 2C0 pCi/L.
In January 1987, radon concentratio-is m the basenteat ranged from 5 pCi/L
when the basement door i%as open, and lose to between -550 Jo 330 pCi/I. at
night when the dooi was closed. When the fan was turned on the basement
l adon eor.centrptions with the door closed varied between 2 to 7 pCi/L,
averaging 3 pCi/L.
•Upha Tiack detectois wese issued in January to obtain long terri average
i adon concent: alior.s.
3. OTHER MEASUREMENTS
Indoor gamma fields ranged from 5 Lo 13 uR/h, averaging 8 uR/h. T!.e
gamma fields around the site \c*iied fiom 5 to 14 uK/li, avp! aging 11 uR/li.
The a\ ei age ladon ennt cil i ation measured with \Ipha Tiai_k detectors o\ er
the period January to Match 19P7 was 1.8 pCi/1. m the basement and 5.7 pC'Y?
in the 11v 111ru c t.
-------
MEASUREMENTS SOM-Mv'Y FOR HOUSE 31
PYLON AB-5 1KXT?LY MONITORING
PHASE MITIGATION
SYSTFM
3 Sub-slab
ventilation;
150 L/s
centrifugal fan
TEST STATUS DLRING
DATE TEST
01/87 work in
progress
Fail on
RADON (pCj/L)
RYNGE MEAN
5-529 290
2-7 3
COMMENTS
o\er 50 hrs.
no fan
o\ er -12 hrs
SYS,r"iM MEASUREMENTS FOR 1K.1SC 31
PHASE MITIGATION SYSTEM 1ATE SYSTEM MF.VSUREMT'NTS CT>1MENTS
PRCSSU?E
I LOU
R-VIXJN
!*a
(l/s)
(pCi/L)
Sub-slab \entilatic>'i; 01/87
250
2
1 -100
Rj t»er
150 L/s centrifugal
250
5
'1 400
Ri ser
B
fan
250
0.5
570
Ri scr
c
250
12
4 600
Ri ser
D
250
3
770
Ri set
E
250
5
2 200
Riser
F
A: End wall
B: Rear wall
C: Rear vail
D: Garage wall
E" Fi ont wall
F: Front wall
TIT
-------
r ~l—¦ cowc.
V
21 -O
&AR&.G-E SLAB CN4 G-RAt>E>
watetr ^
¦e>oF=Ti=NS?t
I RED FtET
gqgr
^fluah;
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TAkJK
A" PVC.
WATER
^UFPL-V
4"4>FV<^
4"<£ pvc
PR2P TH «3U
(TVfr ^F6>)
rnPE^^uJMN
TYP
t^FVC
TKACIC-^r
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5LAg,
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( R.1TJEE
C^rP* <£>v=
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KAKiAL FL-AKi
K6 FAM
LOW COST REDUCTION OF ENDOOR ftADON
FOUNDATION PLAN
Mitigation system: e>ue>-e>'_Ap» e>uc,T"iONJ
Data: I/I2./57
PHASE:FinsAL
HOUSE
NUMBER
21
348
-------
HOUSE 32
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Average radon (Terrade.x)
Radon concentration in water
0.06 WL
200 pCi/L
22 300 pCi/L
1. DESCRIPTION
This single story prefabricated house was built in the early 1920's on a
level site on a large ridge northeast of Reading. The house ualls are of biding.
Heating is by hot v»atcr baseboard collectors.
The unfinished basement ualls are of hollou concrete blocks \. 11h a sill
plate covering Ihe top block voids along the front and back walls, and ith open
\oids at the end walls. Significant floor cracks exist but the perimeter
\»all/floor joint is tight e\eiywhere.
A sump, a well penetration and two uell tanks are located in a pit 1.25 in
square, and 1 m detjp m the rent re of the basement floor area. The pit lias
hollow concrete block \\alls and a concrete floor slab iiid is covered \. ith a
sheet of pl.\v>ood.
2. ACTION
2.1. PHASE 3
The mitigation system chosen for demonsti ation at this site ^as sub-slab
\entilation. The system was modified to access riot onl\ the pei nneter of th«"
basement slab but also the central pit.
In Januaiy 1087, a standard six-point subslah \enlilation sj stem u is
installed, togethei u ith a tightly fitting pl\v»nod eovei over t h >pit and three;
inch ventilation line. \11 pipes connected to .i si\ inch, cential pipe uhieh led to
a plastic bodied centrifugal exhaust fan mounted on an end uall. The fan
.in almost constant suction between 218 and 2oa Pa tt i-ac!: pipe. i'lie
flo< s and radon concentrations in t!ie pipes uere; front wall 3 ! /s at
0 pf'i/1 , 0.J ' /s at '.0 pCi/i , end \%a!l 0.2 L/s at S pC:/I ; i ear \w'll b I /s at
200 pC'j/I , S ! /'s at 10U pCi/l ; gaiage uall ^ l/s at 1G0 pCi/L; .md th;' pit
e:.haust uas >12 l./s at 2n pCi/L.
3 HI
-------
In January, with the s\stem fan off, radon concentrations m the basement
averaged about 7 pCi/L, and with the fan running, conctnti ations dropped to an
average of 1-2 pri/L.
A second check of basement raaon concent rations confirmed Ihe pre\ious
results with an average of 1-2 pCi/L \sith tin; fan c.- anu 5 pCi/L uith the fa*»
off. It \%as found that the I)Eli Alpha Tiack detectoi that nieasuied llie
previous high concentrations had been exposed in the pit with the co\ er on,
and did not lepresent a \aliu measurement of the basement radon
concentrations, if this had been knou n at the time, the house would not ha\e
been selected for 'he project.
-\lpha Track detectors ucre installed upstairs and in the basement to
measure long ter i. averages during tut heating season.
3. OTHER Mi:\SLREMrvis
Indoor gamma radiation vax led fiom 2-18 uli/h, averaging 5 uH/h. Gai?n.i
radiation about the site tanged from 2 to 12 uli/h, averaging 5 uR/h. In e.toh
instance the ma\imui:i of the range wis associated v>ith a hot spot along the
rear \vali, close to the basement \\indnu.
The average radon concenti ution measured \»ith Mplia Track" detectoi s over
the period I.Mr oh to Api ll 1987 \>ys 1.0 jiCi/L in the basement and 3.2 pCi/L in
the livirg area.
.0.0
-------
MEASUREMENTS SUMMARY FOR HOUSE 32
PYLON' AB-5 HOLTvL Y MON' 1T0RING
PHASE
MITIGATION
SYSTEM
ITST
L) VI'K
STA'PJS DLTfING UAIJON (pCi/L)
TEST
Sub-slab + pi t 01/87 Work in
ventilation; progrc-ss
150 L/s Fan on
centrifugal f.iri
01/87 Fan on
Fan off
RANGL ME-YN
1-11
0.7-2.2
C.1-2.7
3-6
1.3
1.2
1
COMMENTS
o\er -12 hrs
o\er 53 lir'j
o\er 17 hrs
o\er -12 Ins
SVSTKM ME\SLIilME\TS FOR HOLSL 32
II'AM: MIT1GY1 LOS S\sriM D\TE S\SiTM MEXSIRKMECI'S COMMENTS
PRFSSLKF FiJOW RADON1
Pa (L/s) (pCi/L)
Sub-slab + pit 01/87
215
0.2
8
Risei
A
ventilation; 150 L/s
2-13
0.3
10
Ri ser
B
centrifugal fan
213
6
260
Risei
C
218
12
25
Riser
D
213
8
190
Ris3r
n
250
2
9
Ri ser
F
2 no
3
160
Riser
c
A: End uall
B: Fix>nt i%all
C: Rear i%al 1
D: Frxun jut
I": Reai unll
F: Fiont ^all
G: Garayf-' wril 1
351
-------
0
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VCAJ4ALFI_XkT-
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0*-tJk
WfN/DC^
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*6;
LOW COST REDUCTSON OF BNOO^ri RAOON
FOUNDATION PLAN
Oat©: 1/J5/67
,, £,UR>-S<-A0 AMP
Mitigation system: weUu V\T eut-TlCKJ
PHASE:FiWAL
HOUSE
NUMBER
22
352
-------
HOUSE 33
PENNSM.VANIA DEN MEASUREMENTS
Working Level grub samples (Kusnet^)
Heating season a\crage radon (lerradex)
Radon concentration in water
0.313 KL
82 pCi/L
660 pCi/L
1. DESCRIPTION
This two story i..; -se with attached gat age has built in the mid 1980's on u
leveled site on the side of n ridg^ to the south of 2ethlehc-in. '1 lie fiur.t wall
of the house is brick, the other walls ai e sidit.g.
The basement walls are of poured concrete. The b.isi mcnt floor has two
large cracks, one across the entr.\ to a small basement enclosure, the other
across the ct-.il.ro of the floor. The gap at the w.ill/floor joint is genc-iall\
small. Theie is an open drj sump with crushed stone in the bottom m one
corne. of the bciserridnl.
2. ACTION
2.1. PHASE 3
As this house was one of the few \ ith a suinp, the mitigation method
chosen foi demonstration \*hs sump \ entilat.on.
The system consisted of a pl\wood pit co\ er sealed to the flour, with a
four inch \ entil.-ition pipe through the header boai d to a lui ge plas-tn. bodied
centrifugal fan.
S>slem testing showed a radon concenti atio.i of 170 pCi/L in the {in-
flowing through the i lser at 5 L/« undet 350 Pa suet'on. Sirmke testing ga\e
ambiguous results along the front v. nil. Although definite flows to below the
slab weie noted at f'.ooi cracks and the pelimotei joint close to the sump, theie
was no indication of fio- at distances greater than 3 m, suggesting pool ai a'ss.
to tin nubslab.
Measurements 11¦ Tebiuaij 1037 found i idon t oni i.r.trali-.nis 1:1 tlie basement
with the fan on langod fiom 12 to 57 pCi/I., 'i\eitiging f>0 pCi/L, and :;ri"gt_d
from G*1 to 07 pCi/1., a\eiaging 81 pCi/L, with the fan off, ulear'.y an
unsatisfacto; \ pel formaik e.
353
-------
The owner's father, who had built the house, advised that the sump
consisted of a solid concrete pipe sitting on soft rock. Holes \»eie drilled in the
wall of the sump crock to improve the connection to the subslab space. The
bottom of the »ump cioclv v>as i>et 111 a la\ei of conciete, cohered uith 70 min of
crushed stone. Holes were drilled tluough the concrete into the fill beneath to
impto\c the conneet ion to th*.1 sub-slab space.
In Murch 1987, with the fan ill operation, lador. concentrations in the
basement axeraged pCi/L, ranged from 3 to 7 pCi/L, averaging 3 pCi/L. When
the fan was turned off the i adon concentrations l anged fioin 1C to 79 pCi/L,
a\ ei aging C5 pCi/L.
Alpha liack dosnnetei s here installed upstan s and in the basement to
detei mine long term aseiage radon fonceutfcijonb.
i. ornrr< mf:\si;rl:mf\ is
Indoor gamm'-i ladialion \aned fi.^i.i G to 8 uR/h averaging 7 uR/h.
F\U iOi' ladiation about the site ranged fioni 7 to 9 uR/'h, avei aging 7 vR/h.
1 he t:\orage radon concer.tiation measured with Mpha Tiack detectors o\ or
the period March to -\pril 1987 was 2.2 pCi/L hi the basement and 1.1 pCi/L in
the 11\ nig e.. ea,
1
-------
MEASUREMENTS SOMWY FOR HOUSE 33
A. PYLON All-5 HOURLY V0XITO1USG
PHASE
MITIGATION
SYSTEM
TEST
DA'rr
STATUS DURING RADOV RLSULTS
TEST
RANGE MLAN
COMMENTS
Sump
ventilation;
150 l./s
centrifugal fan
02/87 Fan on
Kan off
'12-37
68-97
50
84
o\er -11 Ins
over 41 his,
after 6 hour
rise
r mpioved sub-
si ab connection
03/37
Fan oil
Fan off
3- 7
4G-79
o
G5
o\er 4 I his.
0\.er 34 hrs
after 15 in-
i if.-
SYSTEM MEASUREMENTS FOR JICJl'SF 33
HLASE MITIGATION SYSTEM DA IT SYSTEM ME.\SURENE\TS COMMENTS
PRESSURE FIjOK RADON
Pa (L/s) IpCi/L)
3 Sunp \entilation; 02/87 350 5 170 Sump riser
150 L/s centrifugal
fan
! mpi o\ crd ct.iiner-l vc)ii OS/87 350 30 Sunp riser
(o ;vub-slnb
.115
-------
22"-o"
e'-o"
1
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IKJ 6LAB
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6^mc^ETE
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K& FAN
LOW COST REDUCTSOft OF 3ND00R RADON
FOUNDATION PLAN
Mitigation system: 6UE>rScA& vta 5>UMP
Dato: \f?KS/ei
PHASE: p-itsJAL
HOUSE
NUMBER
35
356
-------
HOUSE 34
PENNSYLVANIA DLR ME-\SRE MENTS
forking Level grab samples (kusnetz)
Average radon (Terrade.s)
Radon coneenti at.on in water
2.186 WL
-170 pCi/L
¦1G 300 pCi/L
1. DESCRIPTION
Tins two stor> colonial house with aluminum siding and attached ga:age was
built in the line 1970's on a sloping lot at the top of a small ridge several
miles south of Mlentown. 'I ho foundat'ors walls ai e of pouted conciete with no
evident cracks. 'I he basement floor is also pou;td cone rete but foi ms a
floating slab with n wide pel imt-lei fieiuh d s -tin.
I he house is heated b> oil filed lioL waLei eu dilating thiough eon', eetors
and cooled thiough eential air conditioning. The site slopes f,-om fiont to
back, so the bat k wall is 1 irgely obo\e grade and has a walkout sliding dooi
As tins house had youitd conei ote walls, the nut.gallon measure selected
for demonstration ut this site was multipoint subslab vein '!at ion.
\ sl.tndai d si\ point subslab \entilaiion s;. stem was installed wsir.g the
coiing machine. Ioi'i h I'\ C pij)e i isei s weie caulked irto the slab enti >
point and l<*d thmugh tin .->ist space to a ipam duet fashioned ftoni G inch !'\C
pipe. The sj ste,-.i w is count < ted to .< large- plastic bodied cciti'fugal fan
ms'.a'lod thiough the headi r board of 'he b >ck w i'l.
The 80% of tin interior fi- n<-h diain th^t was tin ectl> ac.essinle w is closed
with minim*. 1 lie o'.iki 20^ was in a woikioom, r*onfeaie: u n \ IPttT niitli itt.fi thi*. bt-foi i the fall w is twined
i.n levels i ringed fioi.i 112 to 8!1 pCi/l., a\ agmg 53 1 pCi/1.. l!owe\ei w'lh
the f in running le\e's fell di :mitirall\ to rr.. _;r ion 3 to S pC'/L a id ! age
J pf"i/i. Suite bast i.ii nt i.nlon i onienlt.ilioiis h id been icduted sie m f :¦ an t\ ,
\lpha "liack r|t t. . toi s were instilled upstaus rind in the basement I r > oht. in
If >ri g 11 i in a' ei -gi s d u i I im I !se 'if it : i: a. si asoi,.
O
\CT10N
2.1.
filNSh: 3
-------
Systerr measurements found suctions in the pipes were betveon 15C and
180 Ti. Flov.s and radon concentrations in the pipes \>ere; front wall 1.2 L/s at
15 000 pCi/L, 2 L/s at 27 000 pCi/L; end wall 5 L/s at 68 pCi/L; rear uall
38 L/s at 820 pCi/L, 25 L/s at 260 pCi/L; garage umII 1.5 L/s at 610 pCi/L. The
high flov> i'.-ites 111 the pipes on the rear v.all neai the unclosed section of I lie
french drain suggested that oveiall performance could b<- improved bj closing it.
This was done bv injecting e\pandmg foain thiough holes drilled in the v.all
covering at the base of the wall.
•\ftei this the sui tion 111 all the pipes '>as between 213 to 210 Pa. Flov*s
in the pipes uere now front wall 2 L/s, 2 L/s; e.id \%all 3 '/•£', rear wall G L/s,
¦>
16 L/s, gai age \»a!l 2 L/s.
3. Orill'R NKASL'mZVCVlS
Indoor garpi'ia radiation ranged fiom f> to 10 iiR/hi averaging 7 ul?/h. Site
radiation ranged fiuni 5 to 10 uli/h, averaging 7 uR/h.
The iiveidiji' rad'm concent i ation neasured with Alplia Ti ack dttectors o.ei
the period I'ebiuaiy to \pi il 1987 1 as 5.5 pCi/L 111 the basement and 3.7 pCi/L
in the living area.
-------
MEASIUKMENTS SOMARY TOR HOJSL-: 3-1
FfLON' \B-5 HOCRL\ >!0\1TOR1\G
PHASE MITIGATION TEST STATLS ni.T?I\'C IIAI^ON ((jOi/!.) COMMENTS
SYSTEM DATi: TEST RANGE MEAN
3 Sub-slab 02/87 Fan off J12-811 531 u\or 120 his
\entilation;
150 L/s Fan on 3- 8 1 over G2 hrs
centrifugal fan
(flinch dram
partly closed)
S^TEM ME.YSI RKNENTS FOR JkTSF 31
I'lIASr
MITIGATION S\STEM DATE
sysids Mr.vsnu^niNTs
PRESSl i?«?
PLOW
1A!X>N
comments
Pa
a'3)
(pCi/L
Sub-slab \enl i lat ion;
02/87
158
1
1-" 000
Riser A
150 L/s centrifugal
170
2
27 000
Riser U
fan
170
5
GS
Rises C
180
38
P20
Risor D
150
25
260
R:s<-r 12
158
«¦»
4.
G10
Ri'-.oi P
Further closuie of
01/87
230
*>
RlSt'I" \
french diaiii
233
o
W\si
-------
2.7-O"
lO- pv'C
4"e -
RJg>TE-£>: I. K1OTTE o ACPA^ MAVE. EX V—,T! N! G- ' PKEWCH PRAj w'
FILLED WITH pCLVueETHAWE. R3^M DUE TO
iwaeC. <^f~ Perimc i e.r was
M<^CTTACE1C> CLC?SED «.
LOW COST REDUCTION OF iNOOOR RA30M
HOUSE
NUMBER
us
FOUNDATION PLAN
Date: zfz&f&l
24
MiM
4«|KII>M
Mitigation system: •^»L(-r--'=-L>A& 1->1 JC-TiCA-l
PhASE:F;s^Al»
360
-------
HOUSE 35
PENNSYLVANIA DFR MEASUREMENTS
Working Level grab samples (lvusnei/)
Heating season average ladon (lerrade\)
Radcn concentration in \ ater
0.931 WL
1-54 pCi/L
527 pCi/L
1. DESCRIPTION
This detached two story colonial house with built in garage was built in the
late 1970's on a steeply sloping site at the top of a ridge a few miles fiuiu
Coopersburg. Heating :s by electric base born d lorivectors upstairs alone, and
there is a forced air cenltal air conditioning system.
The basement contains a double gai age, and a small woi k room. 'I he gaivge
walls are bare concrete and thei c is a crack at one loi net. Three work i ooin
walls are of concreie covered with st>rcfoam belt nut panelling, the fourth is a
frame wall covered with wall-boaid between it and the garage. The wall/floor
joint is visible in th«j garage, and about 1 mm w ide. The floor was pouied in
two pours, and the joint is \ lsible in the gar ige. The sewer line leu\es
through the gaiage wall. There is an opening in the work room wall for the
watei-lme entry, and the sl?b is peneti ited b\ stan suppoi ta and house j/v_ks
filled with concieto.
As this house had a reasonabl \ well \entilated gatage, and solid coacijte
foundation walls, the mitigation s>stem chosen for demonstration at this site
hfis sub-slab \ entil ition applied enl> to (he work room portion of the basement.
,\ foi i--piiint s'.i!»—slT»b \enMlotton s> stem with a l.-*rge nh»st!'_ 'd
cenlrifugfil exhaust fan was installed ;n I ebruary l'J87.
The suction in the pipes was similar, about 260 Pa on average. Plows and
radon concentrations were; end wall 2 l./s at 2 .">00 pCi/l ; front wall 8 ! /s at
770 pCi/L; garage wall .? I /s at GOO pCi/L; and l car wall 3 l./s at f)00 pCi/L. 13}
compai isori, i oom air w:-s I pCi/L, and the water line entrj opening 0 jjCi/I .
In febiuarv 1 OS 7 ttie basement radon concent i ation ranged fiom 0 to
2. ACTION'
2.1
PlIASP 3
3C1
-------
1.6 pCi/L, averaging 0.9 pCi/h. Alpha Truck detectors were therefore installed
in the basement and upstairs to evaluate the long term aveinges.
As confirmation test of s.v stem performance was conducted in March 1987.
Vith the fan on basement radon concent i ations ranged from 0.] to 1.3 pCi/L,
averaging 0.7 pCi/L, kheu the fan ^as turned off levels rose cjuultlv to range
from 37 to 298 pCi/l , averaging 1(5-1 pCi/L.
3. }THER MFASURCMENTS
l!ie interior gamma radiation field vai led fioin 1-5 iiR/h, averaging 5 uR/li.
The e\terior field over the site ranged from 3—i ul?/!1.-
The average ifidon roneenlt ation measured \% i t Ii -\!p!-a Ti.r-k detectors owi
the pence! Febru.ji \ 1o Api il 1987 \v-is 0.7 pCi/L in the basement and 0.8 pCi/L
in I he liv nig a rea.
MiiAsi.TO^iLvrs SONARY ior HOLS IT 35
pylon m-:> intwi ^Kr:nx)Ki.\c
phase mith;\tio\
SYST1 M
n ib
ventilation;
150 L/s
centrifugal (an
TEST
LUre
srvrvs during hvxjn (jC'/d
RANGE ^EAN
TEST
02/87 fan on
0.0-1.6 0.9
cx^Mi.vrs
o\er -1 vn"
Sub-sl ib vent l l,i! ion 02/87
150 l./s ccut r i fug il
fan
S'lTM NF-ASIRIM1V1N
iwssiri: fi.o r.-\:x)v
''a (L./s)
2 500
77C
t)00
900
R
rwu.wi's
Riser A
Risei !1
Riser ('
Riser 1)
Hase'nent air
W iter 1 i no
entt.'. ojK^rurg
V. i'.nd i~al 1
C: Gaiago i.till
li: Front ua!l
!)• Rear ual 1
V>2
-------
2*>-0"
vS
i
"cO
4 4>fvc
H£T
WATEK
TAHK
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TYP.
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WAUL. -]"vP.
4"4> CEOp TMCL)
¦6t_A b (Trr. op ^
FROWT
O.N.Oce^R
LOW COST REDUCTSON OF INDOOR RADON
HOUSE
NUMBER
¦
FOUNDATION PLAN
Oate: K/Sofei
55
« «»•
Mitigation system: t=>L/&-6>i_A&
PHASE: F siAt
363
-------
HOUSE 36
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (kusnet?)
Average radon (Terradex)
Radon concentration in water
0.-105 WL
300 pCi/L
970 pCi/L
1. DESCRIPTION
Tins t\>o story sidesplit house with built in g3iago was built in the eat ly
1980's on a sloping site on the side of a hill south of Allentuwn. The walls are
of wood siding. The cnliancc fo.v or and garage are at g-ade level, but on
separate slabs. The garage has been converted into a bed/sitting l oom. A
large sitting n>om is over the basement.
The basement has poured conci ele walls. There wore no visible flooi
cracks but much of the flooi is covered with carpet and stored material. The
gap at the wall/floo: joint is large, over 1 mm wide in most places. There is a
sump in one corner, which the owner had covered with a metal plate .mJ
passively vented to the outside, and a brick f»repine.c on its own slab. The tup
half of the basement stairs were set into a recess in the house/basement wall.
The foyer slab is pr)in *d inside the concrete foundation walls, and has sunk
2 mm, cracking the vinyl tiie in places around the slab perimeter.
2. ACTION
2.1. PHASF 3
The mitiyative action selected for demonstration at this house was
integi'ited subslib v entilat "ori beneath both the basement and the fov er slabs.
A diamond coring di ill was used to drill foul 125 mm diameter tides in the
floor slab a; the appi o\im.uo centre of each wall, and two 125 min holes in tin
stub wall to access the fill beneath the upper level slab. Some difficulty was
experienced in drilling the fnst hole tiiiough the stub wall, foi the nreu on the
otliei side of tlie 200 mm thick concrete wall was filled to a depth of more thin
•150 mm with solid concrete. The coring machine gearbox failed after di tiling to
this depth, and a second machine had to be obtained.
Tout inch PVC pipe was installed at each floor and wall ent: v pomt and
connected via a s:\ inch 1'VC pipe to a large plastic bodied cei'li ifug'il fan
3G-I
-------
located outside the back wall. The existing sump ventilation system v.as teed
into the new system with a damper. There was a 1 in square area of exposed
soil covered with crushed rock in the recess beneath the basement stan s. A 30
mm thick layer of concrete was poured over this to decrease the exposed soil
area in the house.
In February 1987, while work was in progress, radon concenti ations ianged
from 6G to 170 pCi/L, a\ernging 125 pCi/L in the basement, but fell rap.dly
when the fan was turned on to range from 1 to -I pCi/L, averaging 2 pi" >/L.
The suction in the system pipes was about 112 Pa, and -12 Pa in the sump
pipe. The flow s and radon concent: ations in the pipes wore; end wall 13 L/s at
80 pCi/L; front wall 14 L/s at 440 pCi/L; stub wall 22 L/s at 700 pCi/L, garage
end wall 2 L/s at 1 500 pCi/L, teed slab plus wall entry at garage end uo.ll
9 L/s at ICO pCi/L, sump 3 L/s at 580 pCi/L, and fiont uall 20 L/s at
280 pCi/L. Smoke testing showed all cracks, the basement perimeter wall/floor
join', and the peiur.eter joint round the upper slab were all at lower piessuie
than the house.
Alpha Track detectors were issued in March 1987 to detei mine longei tetKi
averages upstairs and in the basement.
The exhaust fan here was installed in the opening that the ownei had made
for the sump exhaust, and pointed upwards towards an overhanging soffit. Uben
warmer weather came, the ow pel opened the kitchen windows, and complained
that tV> exhaust air f:o.n the fan, which smelt of soil molds, was blown into the
house.
The opportunity was taken to investigate ret n dilation of the fail exhaust.
In April 1987, alpha tiack detectors were pCi/l , and was 11 pCi/1. at 3 m on "ither side. The
moiisuicd barkgioued "it the fion' of the house was 1 pCi/l . This su_f;.;es!-> 'hat
the average externa! i adon cum enti at ion produced by the giuunii nui'mied f-*ns
3f,"
-------
is not high enough to increase the average interior radon concentration
significantly, as long as the discharged air is only a fraction of the air that
enters the house. This can be expected to be the case in v> inter vhen % indous
are closed, but might nol be true in summer time \\hen windows on the fan side
of the house might be open. A horizontal discharge rPong the ground a\»ay f: om
the house might ha\ e given louer concentrations.
As a test, the fan v»as reversed to pressurize the system, and eliminate the
discharge. - Radon concentrations in >!av 1987, shoued an aveiage of ! pCi/L in
the basement, and a high of 4 pCi/L. Despite the lo\% radon ie* p's, the
re\ erscH sj stem drove enough soil gas into the buserieut to return 'he smell
tliei e to the level that existed before the system was installed The ovr.ei did
not like the irustv smell -nid i equested that the fan be letumed to :ls ^rigma'
o: lentation. This \»as done.
In June 19^7, -is a final solution to recirculation e\lrtust g.'scs, j -1 inch
l'\ C riser uas attached to the fan through :• 6/4 inch reducer and '».»=> run
underneath the soffit to the end of the house to e\haust above the roof. The
piping i%as painted to 'natch the v.'ood siding.
c. ot'iizr Mr\si'Ri:\CNrs
Th° gn ">>"¦-» ra.'iation fi-Md in the house ranged from t> to 9 uR/h, av tinging
7 uH/h. Outdoor gamma fields aiound the site ranged froir 3 u'v/h o.i the
asphalt drivi.1. ny, to 10 u!?/h and a\et:-ged 7 i»K/h.
The average radon runrenti a lion measured \»;th Mpha Tiack detri. t ir-i o.'ci
the period Male!; to \p'-il 19P7 was l.G pCi/1. >n the basement and 1.7 pC-./L. in
the living area.
36G
-------
MEASUREMENTS SUMMARY FOR HOUSE 3G
PYLON A»-5 HOURLY MONITOR 1\'G
PHASE MLTTGATION'
SYSTEM
3 Sub-slab
\entilatior.
150 L/s
centrifugal fan
TEST
date
02/87
STATUS DURING RAIJOV (jy.:i/L)
TES r RVNGE MEAN
Work in
progress
Fan on
C6-170
1 •; 2
125
05/87 Fan levererxl to 0-
bluu
I 1
COTIENI'S
o\(ii 3 djjfa
o\er 3.5 da\
o> or 88 In b
icturned to
smcLion at
oivnorii'
l oquest
sysiem MEASumr-nivrs for ikxsl 30
I'll-VSl- MITIC\T10N SYSTEM DYTE S\STT?l MKVSURlMt'_V!'S LTWL'NTS
Ili'irsSl R! n/)\s RADON
IN (L/s) (pTi/L)
Sub-slab \fjnLi lalion; 02/87
1 ;2
13
SO
Kibcr \
130 L/s cent i . filial
137
IK
280
KB
fan
14
-1 10
K':bv.T t"
117
22
7 SO
' V: h.-j ¦ D
112
1 500
Ris'.-r 1
i I 2
9
1C0
R i sei' i"-F
-12
3
5R0
Sun:;> IjiiC
diunpt.'rt.'d
\: 1 nd ual 1
U. Rear (fori) wall
" ! i ,>ni \ .i 11
D. Stub wall
l : 11
I'. .111 < ill i y
-------
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FSOWT
LOW COST REDUCTION OF INDOOR RADON
HOUSE
NUMBER
HUSK!
FOUNDATION PLAN
Data: Z,i\~i.'&7
36
Mm
JMMlllNM
Mitigation system: <£ub-^iar -^Lk^.Tiom
PHASE: FlfsMJ-
36b
-------
HOUSE 37
PEXN'SYLV \X1\ DER MLASCRCMPVTS
Vorking Le\el grab samples (Kusnetz)
Average radon (Terrades)
Radon concentration in \%atei
0.25G KI
87 pCi/L
2 200 pCi/L
1. DLSCJMPTiON
This tv»o-stor> house uith family room on attached slab and attached double
garage uas built m the mid 1980's on a rural site on lop of a i idge lo the
south of. Mncuiigie. Tlio front uall :s fated \%ilh random stone.' and the other
v^alls nit.' clad vith jiuminum siding. Heating is bj a conl-fn ed 'x.sement
fmnace pio\idmg hut \ ati*r in baseboard convectors and a small coal-burning
stovp i" "ic fannl;. i nor".
The foundation walls are of poured concrete, ard tlieie is an e\temal
entrance to the basement. The v. nils a-e peneliated by sewei, vatei , md
oil-fill lines. Tl:i* pooled concrete floor slab has a ir.ajoi cuicli and is
peri'.tr.ilf d Vy tuo hollo\ steel jacks, bvst no f!oo: drains. !"he ou-lei said lhal
there uas an tinder-slab loo;> <>f j.ei forated pipe connected In a sump, \>h:ch ivis
sealed as lh!iii.!i
t vleiuitrd ulj' f I < i. I" '• e ".va'l. ^ dlllleJ •''.'•OL'gl' tl» 0 CO 'CI* loo'- I"
ihipro\e the ""^nrit'Ct!. in to 1 lie so.1.
On j' • I fit_ fan Lja\ a st'ion o'" 1 1G l'i in eacn pipe. The f!n,s an i
r idoii (onft. -.'.i atioi.s \%eit.; end uall y L/^-i at t'7> pCi/l , i e.n \ ill !7 5 /s a!
150 pCi/l., 23 L/s at Gt pCi/L, garage -all 0.2 L/s at 9 pCi/I ; f: out Vval! 21 I/s
a! '10 pCi/I., 20 L/s at >-12 pCi/L. Th" lo' f!ov-' pipe vas 'ho one ii- I lie footing.
Piasein*'!radon concentrations hi Pt-binar\ IDS", , an^c-d fii"; OJj Lo
2.0 p'"i/l , vvitl; an a>eiag« of 1.5 p'":/L .
VTfO
I'l'-Wl J
350
-------
On the basis of those low radon concentrations, Alpha Tiack detectors were
installed upstairs and in the basement to obtain long term averages during the
heating season.
However, the flow rates in the system were laige, and the radon
concentrations in the e.shaust air were low, so the wall/floor joint was closed
by caulking to test if the air was coming from the house via the wall/floor
joint, or v^as drawn directlv through the soil. This increused the suction to
approximate^ 145 Pa at earh pipe. The flows and lador. concenti at ions wi.ro,
end wall 7 L/s, 900 pCi/L; rear wall 13 l./s at 120 pCi/L, 18 L/t> at. 210 pCi/L,
end wall 0.02 L/s at 1 pCi/L; 1-1 L/s at 130 p(/i/L, 11 L/s at 110 pCi/L.
Although closing the wall/floor joint did reduce tin- total s\ stem f'.uw fi o 1:1 n0
to 66 L/s, the flows were still large, and the radon concentrations low. Tins
indicated that the so'l pemeabihtv at this .%.!<• was higher than usual foi the
area geneiallj.
In March !9S7 Ihe hjsC'iorit concentrations wcie reir.easui ed. With the fan
on the le\ els. umyu 0.0 to 1.° pOi/L, a\er igmg 0.6 pCi/i . Ulien t'n»
system was turned off, radon coricenti ations i ose I o lange froni 10 to 33 pOi/1,
a\e*aging 19 pCi/L. This maximum was less than h".:g!.t be c%po' tod f.oni the
III K i?easi• renieiits, and is probably lowei because the wall/floor joint had beee
caulked. Tha! i adon concer.tr.-itions weie s!i!l m the 20 pri/1 if. g,oi' aft*,
closing tln-3 1 n'ge and obvious openmtr shows t>'e tiiffit u't> of eff< -tlx e!\ ¦^e.ih.-'g
a basement against soil ga-. ei.tr>.
Furthei i :u(oi' monitoring w.is conJii«.t"d :m Apt il 19117 i.i the at»a> li.-d sLib-
on-grii."1'' fami'.N ioo.v. All concenti at ions o* or a four iki\ petioj in \p> i' f>ie
th.-in 1 pCi/!..
?. O! HTR Ml- '.Sl'Hh'MI V! S
Ii.di'Oi gamma fields ringed fio.n I lo '! nii/'i, in t*i ij u'i/h S'ti
gainrn. ladMtion ranged f-osr. 5 to P. uK/1., a\ci aging 7 iilv'/li.
111-.' a\eiage radon ffn..v' tiation nie.'isii.ed with Alpha Pi'irk d- tee toi s o\ ei
the perio 1 Pebruar.\ to April 19.S7 was 'J.G pCi/L in the 1-asomoni and 0.(1 pCi/I
in the living aiea.
370
-------
ME-VSl/REMENTS SbTlARY FOR HOUSE 37
A. HYLON .\li-5 HOURLN MONITORING
PHASE MITlG\riO\
SYSTEM
3 Sub-slab
vi j. la t Ion;
MO I./s
centrifugal fan
As alxne +
wall/floor joint.
caulked
TEST
date
02/37
STATUS DURING RADON (pCi/D
tes r
Fan on
03/87 Fan on
Fan off
RANGE ^1EA\
0.G-2.0 1.5
0.0- 1.0
10 - 33
0.G
lfJ
COMMENTS
o\er 4 davt>
over 44 hrs
o\er 4 1 hrsJ
01/S7 Fan on
0.0 -1.0
o.;
o1 or 1 (lavs
upstair s
famjl\ room
SYSTEM MT_\SnilMENTS FOR 1 !OUSL 37
rn-vsr virri(jyt ion s\srEM D-vri- system mexslIiCments comments
PR! SSFKL
HjO'a
RADON
(L/s)
(iCi/L.)
Sub-slab \ f-.nt i Lit. i cm; 02/^7
138
o
75
Ri^er \
150 L/s r'cni.i i fii^.il
12.1
17
150
Ri^ei B
fa-i
ioa
23
CI
Rii-er C
l or.
0.2
0
Rlbl'l l)
105
21
110
KlfetT L
i 13
1£0
82
Riafj 1'
\s nbo.c *¦ ill/floor 01/S7
joint caulKrsl
1 15
1
100
Riser \
163
13
120
Riser U
1 n
210
'Iiwr C
130
0.02
1
Riser 1)
! 18
! 1
130
Riser L
1
1 1
1 10
K i so i I-
-\: 1 r»! •1
li" Rear i.a 1 1
C: Rear will
I): Gai.'i^' u« M
1*.: I t or it \ al 1
F: Fi i nit wa 1 1
-------
KAMAx-PL&KT
FAJsi
C^ruc-RETE :
R5L-KJDA^-.fPU
WAL-J— "prp
-¦3L-A3 ;
Ff?A£.TVRS9
•j>CAL-ED
COAL-—
1=1 REP
6riuER
familv bsom
.^>LA& c?N GrKAC>K->,
£>UM
PHASE:FiMAL
372
-------
HOUSE 38
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Hunting season average (RP1SL')
Heating season radon avetage (Terrade\)
Rudon concentration in water
0.595 WL
0.370 WL
303 pCi/L
11 800 pCi/L
1. DESCRIPTION
This two-stoi y house was built in tho early 1980's on a sloping site on the
side of a hill some miles northeast of Bovertewn. The lower front vail is
sheathed in bri'.k, and the other walls aie covered with siding. The bHscraui.'
walls arc of hollow concrete block, closed at the top with cap blocks, and half
of the basement is a garage with a central floor drain. The other half is
finished with a laundrj room which has a trapped floor drain, bathroom and a
family room with panelled walls, brick fireplace, plaster ceiling and tiled floor.
The concrete floor slab was poured in two se&tions, and about half of the
joint is \ lsible ir> tho gaiage. There is an open french drain visible in the
garage at the end wall and along the rear wall, which the owner sud extended
beneath the tea: and end walls .u the finished half of the basement. The ownet
said that there was T--6 inches of crushed rock beneath the slab, a crushed sto.ie
drain around the footings, and that the floor dram in the garage discluuged to
da.\ light on tho bank in front of the house.
As the own«'i said that the house had .111 exterior dram, the mitigation
im thod seh'i led for demonstration in this house was drain tile ventilation.
Later information fiom the house buildei was thi-t there was no crushed ro«.lv
round the footing. This made the success of the selected method doubtful, and
work in this house was suspended until Phase 2 of the program, when mnj e
would be Known iboul alternate successful mitigative methods.
The mitigation method selected fui demonstration in this lions? v-.ts w.ill
plus floor \ ent il.it ion. tlowe\.>r. the < \p.-.ise and difficulties met with othei
373
2. ACTION
r:r» sr 1
O 1
I'M \SI. L'
-------
Phase 2 installations led to a re-evaluation of the value of this mitigation
method, and consequent^ work at this house was suspended until later in the
program, when more would be known about alternative successful mitigative
methods.
2.3. PHASE 3
The success in Phase 2 of sub-slab ventilation for houses with concrete
hlock walls led to the selection of sub-slab ventilation as the mitigation method
to be demonstrated in this house.
Tn rebruarj 1987, radon concentrations in the basement \aried froin 190 to
860 pCi/L, averaging 375 pCi/L. Radon measurements in the garage and lauudrj
floor drains ga\ e radon concentrations comparable to those in the house air,
and were not regarded as likely entry routes. A two point sub-slab exhaust
system v>as selected for this house to take advantage of the thick layer of
crushed stone beneath the basement floor and to minimise the work in the
finished area. The exhaust points were to be placed in the half of the slab
that lay under the finished rooms.
The system was installed in March 1987. The initial positions selected for
the exhaust pipef were at the rear of the laundry room and in a closet beneath
the front stairs winch also contained the well tank. However, there was not
enough space in the closet to use the coring machine, and so the second poinl
was placed outside the closet by the front wall. Doth pipes were teed together,
and connected to a large plastic bodied centrifugal fun placed ori the rear wall.
The french drain wus closed in the garage bj placing gravel in J he bottom
so that it could still dram water from the wall footing to the sub-slab space,
and tin n tilling the tiough to Invel with the floor with moi tar. The visible pat t
of the floor joint was closed with silicone caulk.
The fan pioduced a suction of 238 I'a in the laundry room pipe with a flow
of 27 L/s at OTO pCi/l.; ai»d a suction of 238 l'a in the front pipe with :i flow
of 1G J,/s at 340 pCi/l. in the front wall pipe. With the fan in operation, radon
foncentrations in the basement ranged from 8 to 77 pCi/L, averaging -10 pCi/L;
and upstairs radon concentrations ranged from 2 to 55 pCi/L, averaging 30 pCi/L.
'I he lower cvrii-'-nti ¦>! ions were associated with the doors being open.
\ smoke test through joints in the paneling found thai the fan suction dici
not extend across the finished at e.i floor. The fiench dram behind the paneling
was filled with expanding ur«>lh ine foam, injected through CO mm holes di illed at
37}
-------
500 mm intervals through the bottom of the paneling and the sole plate into the
drain. A long nozzle was placed diagonally into u hole, and foam injected until
it appeared at the ne\t hole in that direction. The foam continued to expand
over tune, and £> 10 15 cm diameter bubble of foam was forced out of most
holes. A layer of self-adhesive pointer's edging paper had been laid by the wall,
ao the foam lay on top of this and did not adhere to the tile. V.'hen it was.
fully set, the foam was cut off flush to the vail with a bread knife. The holes
were then concealed by placing a prefinished 2 inch baseboard along the base of
the walls.
This reduction in floor leakage area did not change the suction in the
laundry room pipe which remained at 238 Pa with a flow of 25 L/s at
1 500 pCi/L. The suction at the front pipe increased to 350 Pa, but the flow
remained at 1G L/s at 390 pCi/L. This suggested that the air was being diaua
into the sub-slab space through openings in the walls at footing level, and
perhaps through the soil itself.
In March 1987, following this work, the radon concentrations in the
basement ranged from 2 to 14 pCi/L, a\ ei-aging 5 pCi/L, while radon
concentrations upstairs ranged from 2 to 12 pCi/L, averaging 5 pCi/I.. The
highest values were associated with water use.
Alpha track detectors were issued m March to pio\ide a longer term
estimate of average i adon concentration.
3. OTHER MEASUREMENTS
The radiation field in the house ranged from 3 to 12 uR/h, a\craging
10 uR/h m the family room. The field over the site tanged fiom 8 to 12 uR/h,
averaging 10 uR/h.
The average radon concentration mt'jsuied b\ alpha-track detectors over
the period March to April 1937 was 11.1 pCi/L in the bnsenient, and 11.2 pC;/L
in the 11\ing area.
375
-------
MEASURTMENTS SUGARY PON HOI'SE 38
PYLON AD-5 I 10CRLY MONITORING
PHASE MITIGATION 7ITT
SYSTEM DATE
3 I'rerai tigation 02/87
3 Sub-slab 03/87
ventilation
150 L/s
centrifugal fan
3 As :vbo\e »«ith 03/87
closure of
french dra: n
completed
ST-YTL'S MTIW P\D0N (pCi/L>
RAN'GL MEAN
TEST
Survey
Fan on
Fan on
Fan on closure
in progress
Tan on closure
complete
189-8C2
8- 77
2- 55
2-
2-
7
9
375
40
30
3- 14
2- 12
5
5
COttlENTS
on er 4 days
over 48 lirs B
over 48 hrs I!
over 26 lirs B
over 2G hrs L'
over 66 hrs B
over 66 hrs l"
PHASE
SYSTEM MJLASLTJTT'HZNTS FOR HOUSE 38
MITIGATION SYSTEM DATE SYSTEM MEVSLTvEMENTS
PRESSURE FLOW RADON
l»remitigat ion 01/81
Sub-ilaVi \ ont i ] at. i on 03/fti
150 L/s centrifugal
fan
Closure of ficm h 03/87
dram completed
Pa
238
238
350
238
(L/s) (pCi/L)
60
150
16
27
16
25
340
980
16
8
390
1 500
COMMENTS
parage dram
i.u&hroo:n air
Riser A
Riser 15
basiersent
upstairs
Riser A
Riser D
A: Front *-alJ
Fl: Bas'wiit
C: I«)iinrli.\ room
l": 1 fetalis.
376
-------
R5>LVukETH4N E F(?AM
*=»U!_ ltS'PREN«L-M^RA»M
"inggPLazg
FIMI6UED FAMILY CM.
C ETTC-H
P'-PREUCW"
C»R4JMtyp
!^r
WASKEf?
^ITfPBOP
THRU
C&L-A.0.
ALL U\pPV£-
O.H.
PtocR.
gARA^rE
RAMlL-V t5M.
EUC.VATIOS4 flM WAU.IU
=" - " Js"=icgAiM
yUOULOW C^KIC..
v -©t^*4C.Ra;Nt>&nTON
WALX- TVP.
|-W|6JC«5VV^
pavc-e g-E'.-cr'V
C-OL.C» WATER
tamk.
,"4>FVC. Dfircp
"THRU "OLA©
FROUT
LOW COST REDUCTION OF INDOOR RADON
HOUSE
NUMBER
iilS
FOUNDATION PLAN
Dat«: &/C/&7
58
MtN
Mitigation «y«t«m: *5ue>-^i_Ae» $U6TiOM
PHASE: FiMAJ-
377
-------
HOUSE 39
PENNSYLVANIA DER MEASUREMENTS
Working Level grab samples (Kusnetz)
Average radon (Terracfex)
Radon concentration in water
0.3-15 UL
111 pCi/L
low (municipal wuler)
1. DESCRIPTION
This one story house with built in garage was built in the late 1960's cn a
small levelled lot partway up the side of a steeply slopinj ridge in the south of
Allentovn. The walls are covered witli aluminum sidling. He.i.ing is by electric
baseboards in the basement room and electt ic radiant ceiling units upstairs,
where there is an unused fireplace and a vood stove. The vood sto\ e is the
main source of heat during of heat during the uinter.
Only the rear of the basement is in the ground, and it contains a garage
and a laundry room at one end, and a work room at the other. The house front
entrance is in the middle of the front basement wall, with stairs to the.- Eidin
floor. The basement valla are of hollow concrete blocks vhich have been
mortared closed at the top. The walls are exposed only in the garage, and are
covered by fiberglass insulation battens in wooden fiannng in the work room,
arid b> uull board in the laundry room. The poured concrete slab is vithout
cracks. T-he wall/floor joint at the back vail has been caulked uith abphaKtc
sealant and an asphalt coated wooden strip has been installed 50 irm out from
the vail lo form a Liuinne] to divert vater leakage to the garage and outside.
The slab is penetrated b.\ two hollow floor jacks, a water l:n«' and a s^ver line.
Only the back vail and part of the end vail are belov gi ado.
The owner indicated that there vas a plastic bonier belov the shit) but
probably no subslab aggiegate.
2. ACTION
2.1. PHASE 3
As this house had hollow concrete block walls below grade on tvo sides
onl> and the slab built direct!} on bedrock the mitigation method chosen foi
demonstration was subslab ventilation. The aim vas to demonstrate liut
basements villi hollov block subgrade valis and poor subslab pei r:i-abililj eovild
378
-------
be treated with suction points placed close to the walls and with high suction
fans.
In May 1987, premitigation testing of the sub-slab permeabilit.. was
conducted using a vacuum cleaner to suck on holes dtilled through the slab.
The e\tent and stiength of the suction induced at nearby holes was investigated
using a smoke pencil and pressure measurements. Communication between holes
was not detectable except at one location at the rear of the house, where a
suction of 13 Pa was measured at one hole when a suction of 13 000 Pa was
applied to a hole 2.5 m auay. Probes found a mixture of clay and rock beneath
the floor.
Radon concentrations in air sampLa taken from the drilled holes were 2 000
and 10 000 pCi/L by the garage (rear) wall, 2 -100 pCi/L near the rear work
room wall, 1 -100 by the front work room wall, 1 300 pCi/L by the front laundry-
room wall, and 380 from an cpen'ng by the water meter. Basement aii
concentrations o\ er a foi r day period varied between 1 and 63 pCi/L and
averaged 24 pCi/L. The low concentrations were assoc:ated with the garage
door being open for much of the day.
A three point .sub-slab ventilation s\stem with '.wo access points close to
the garage wall, and one near the centre of the b
-------
3. OTHER MEASUREMENTS
Indoor radiation fields ranged from 7 to 11 uR/h, averaging 9 uR/h. On
the surrounding site the field ranged from 9 to IS uR/h.
3P.0
-------
MEASUREMENTS SUMMARY FDR HOUSE 39
PYLON' AH-5 HOURLY MONITORING
PHASE
MITIGATION
TEST
STATUS DURING
RADON
(pCi/L)
COMMENTS
SYSTEM
DATE
TEST
RANGE
MEAN
3
Premitigation
05/87
Sur\ ey
1-63
21
o\er 1 days
3
Sub-slab
06/87
Kitliout fan
0-50
Over 20 hrs
ventilation
work in
150 L/s
progress
centri fugal fan
Fan on
0- 9
2
o\er G6 his
SYSTEM MEASUREMENTS TOR HOUSE 3D
PRASE MITIGATION S\STFM DATE
Preroitigation testing 05/87
SYSTEM MEASUREMENTS
PRESSURE FLOW RADON
Pa (L/s) (pCi/LJ
19 000
10 000
2 400
1 -100
1 300
3P0
COMMENTS
Hole A- rear
^•all gaiiige
Hole B- rear
wall garage
Hole C rear
vail workroom
Hole D front
ual] workroon
Hole E front
uall laundr\
Hole F front
wall Kaler
met ei
13
000 Iva su.tion
0
some f1ow
A-D
at
test hole
0
some flow
C-D
13
some flow
C-U
0
no floi%
E-A
0
^nrno n0u
E-D
0
some Hoi.
E-F
Sut(-slab ventilation; 0G/87
150 L/s centrifugal
fan
325 0.9 3 200
275 0.8 3 800
275 11 1G
325 1G -160
8
Riser 1 reai
wal 1 gatatje
Riser 2 -rear
wall workroom
Riser 3- rear
wull isoil.iocjra
at fan
Kor troom aji
no 1
-------
-SLOPE
0
1
0
. I
0
nS
_ i
to
N
I
o-
zz-o'
I \'-o'
e'-o"
KAWAL^UAWCT-
K.& F^N .
(yERTVAt-X-Y)
RktrrmcM
lj?
"TWELi te,
CTVPL-A&-^
BtA£»CMEJJT
SF'
; r4u4> Pi®^
/ COLJJMN Vk/
if POLYUK6THAME
— f—RCAM Pill
/
CWAU.
¦AvCC> R
< /'tr--=>To^E RUB^'-E
^ RETAl MI MCr V/AL t_
W1MPus-$LAB -sucti^w
Date: &/'.(,/&7
PHASEtFiUAL
HOUSE
NUMBER
382
-------
HOUSE 40
Pennsylvania der measurements
Working Level grab samples (Kusr.etz)
Average radon (Terradex)
Radon concenti ntion in water
1.15 KL
1-18 pCi/L
low (municipal water)
1. DESCRIPTION
This very large two story detached house with attached garage was built in
the eai 1> 19G0's on a level site :it the top of a Iidge to the north of Easton.
The fionl wall and one end wall is sheathed in brick, with cedar shakes
elsew here.
The house is heated by electric radiant heaters ir» the ceiling and two
fireplaces which ai e back-lo-baok on the first floor, supported b> a large
concrete block structure in the centre of the basement. Air conditioning is by
small window units.
The basement is unfinished with walls and floor of poured concrete, and is
divided into four rooms by concrete block internal walls. Theie is an external
entrance into one too.n used as a work room. The floor has poured separately
in each room, and there are construction joints at each doorway. 'Iheie a:-'.' no
other visible cracks in the walls or slabs. The steel jacks whioh supper', the
suspended floor are hollow and penetrate the b isement flooi slab. Then; 'j a
large wall/floor shrinkage gap around the perimeter of the slabs. The owner
lepoiled that the builder had told htm that there was no crushed lock beneath
the basement floor.
2. ACTION
2.1. 1MIASC 3
As this house was very largo, 230 in* of basement, and was probably built
on low permeability b"drock without any inter\ening crushed rock plenum, the
mitigation method chosen Tor demonstration at this .site was sub-slab ventilation.
In May 1987, preinitigation testing was conducted using a vacuum cleaner to
sue)? on holes drilled thiough the slab whilu in\ estigstmg the e\lent and
strength of suction ,it ncarbj holes and openings with a smoke pencil and
piessure me ism eim-nts. An nidus' ri il 1/2 n.ch hammer drill with a 3/8 inch bit
383
-------
was used to drill through the floor slabs. Each hole took several minutes to
drill, as the bit frequently struck hard pieces of aggregate that took a !cng time
to drill through.
No communication could be measured betueen the holes. No airflow uas
produced down several holes even when 13 000 Tu suction uas applied to a hole
less than 1 m away, l'robes shoved that the slab had been poured directly on
low permeability boil and broken bedrock. Sounding vith a metal bar shewed
that the floor was in poor contact with the soil near the perimeter walls, and
smoke was drawi verj slowly down Uo holes there.
Air samples drawn from the interior of the hollow block walls showed radon
concentrations ranging from 32 to 2-40 pCi/L. The basement air radon
concentration was in the region of 10 pCi/L at the time and for 3 da;, s
monitoring ranged from 22 to 209 pCi/L a\eraging 113 pCi/L. Air samples from
three holes drilled in the floor slab gave radon concentrations of 3 700 pCi/L
in the end room, 5 *300 pCi/L in the front room, and IC 300 i".Ci/L m the
workroom. Although the walls were loutes of radori entry, the rudon
concentrations found there in comparison to those beneath the floor, suggested
that they were not p.iajor ones.
To check that the wall/floor joint was a route of entr>, despite the \ -,*ry
low sub-slab permeabilitj , twelve enclosures were placed over wall/flooi joints.
The radon concentrations in the enclosures after 24 hour3 were; end room 770,
2 400 pCi/L on external walls; front rooru 1 900, 1 400 pCi/L on exteinai wails,
and 2 100, 1 000, 2-10 pCi/L on internal block wulls; re^ir room 100, 250 pCi/L on
internal block walls; work room 1 800, 7 400 on external i-alls and o70 iiCi/L o.i
an internal block wall. The radon concentration in the basement air .»us
100 pCi/L. There was no correlation between the size of the wall/floor j^int
and the ladon coriceriti a lion iri the enclosure. A number of the enclosure** hid
radon concentrations, that were a lai ge fraction of the sub-sl.''b soil gas
concen* rat io.-is, so the wall/fli or joint was a probable enti } loules.
The sub-slab permenbiht \ tesl ga\ e no guidance for t'.e s\f>tem di-sigr.,
e.xc-pl that one i'un would probabls be sufficient to handle all I he air that
could he extracted from the sub-slab space, so the standard design uas jsed
wnh exhavist points located near the outside walls and near mtt run! ronevte
block walls with .a nominal separt.ion of 4 m. This lead to a twenij - point sub-
3HI
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slab ventilation system, which was installed in the basement o\cr a sis day
period in June 1987.
A large plastic bodied eonti lfugal fan installed in a window veil nt the end
vail provided suction to a 6 inch duct which split into two parallel G inch ducts
which ran thiough the front nnd rear basement rooms and into the work room,
l-'our pipes for the end room came off the main duct, and eight pipes ran from
each duct after the split. The 12f> mm diameter holes for the exhaust pipes
were made with a coring drill. The low permeability of the sub-slab fill was
confirmed, for the drill cooling water did not drain down the hole, and e\ti acted
soil contained a great ileal of clay. To increase the effective permeabilit>, the
soil and broken bedrock uere removed as far under the slab as possible and
replaced b.s clean crushed stone. The hollow steel house jacks were diillod and
filled with expanding foam tu increase the airtightness of the flooi.
While the wotkmen installed the system, the external basement door was
open all the working day. Radon concentrations in the basement vat ied from 10
to 50 pCi/L under these conditions, and rose to as high as 133 pCi/L when work
was finished and the door closed at night. When the system fan was turned o:i
radon concentrations dropped, tanging from 2 to S pCi/L, and averaging
3 pCi/L.
System testing found that the suction in the e\'iaust pipes v.. ¦. almost
constant, ranging from 250 to 2~^ Pa, with Hie higher suctions in the pipes
nearer tin' fan. Flows in the pipes were vorj low, all in the region of 0.3 I./s.
Onlv one pipe had a flow 1 !./s or more. The total flow to the fan was only
24 L/s, confirming the low permeability of the sub-slab material. Radon
concentrations in the pipes \ .fined wide)\. Along the end wall of the house,
radon concentrations were 830, 730 pCi/L, along the rear wall they wei e 9 000,
22 000, C 200, 290, 1 500, 340 pCi/L, along the garage wall 1 600. 3 100 pO/t.,
and along the front wall 1 300, 3 700, 1 800, 1 9C0, 4 100 pCi/L. Radon
concentratlon^ in pipes near the internal block walls and chimney sti ucture were
lo\ or, at 200, 1 700, 1G0, 29, and 270 pCi/L.
The pipes with the highest ladon concenti ations wore not m the aicas
where the enclosuies had high radon concontititions, but were close- to the .ii e.i
of the ba-verieut w he: e the iadiation I; vel was 50% higher than nor-nal. P>e
higher im(JmI.ioii is probablj caused 1?> localised .'one in the bedroik of hi^he:
385
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uranium content, and this in turn would also give higher 1 adon conceal i utions in
soil gas.
Alpha Track dosimeters wore installed upstairs and in the basement 111 June
1987 to measure the long term average radon concentration.
3. OTHER MEASUREMENTS
Indoor gamma radiation ranged from 6 to 10 uR/h, a\eraging 8 uR/h.
There was a hot spot of 16 uR/h about 3 m in diametui in the basement end
room. Gamma radiation over the site varied from 9 to 11 uR/h, a\erag:ng
10 uR/h.
MEASUREMENTS SLMHW TOR MOOSE -10
PYIDV AB-t IKXJRLY s)0\' 1 TOR 1NG
PHASF MLTTGAT10\:
S\STTM
3 Premi tligation
3 Sub-slab
\enti Lit, i on
TEST ST Vn,S DURIVG RA1XA' (pCi/L)
D\TE TEST R.YNGE MEAN'
05/87 Survoy
06/87 Work in
pi ogress no fan
22-209 113
10-133 52
06/87 Tan on 2-4 3
SYSTEM MMVSURFMEVTS FOR HOL'SE 40
COMMENTS
over CO hrs.
o\er 70 lus
ccJ lar door
ojx:n
o\er f>7 hrs
PrfmLtigat-ion
t.esti ng
05/8;
For al1
combin.it i "iis
of blab holci>
13 000 I'.i
appl i M
380
-------
SYSTEM MEASUREMENTS FX)U llOL'SE 10 (COST. )
PHASE
MITIGATION SYSTEM DATE
SYSTEM MEASUREMENTS
lliESSUUE FIjOW RADON
Pa
Sub-slab ventilation 06/87 210
250
250
250
250
2C5
2C5
2C5
275
275
275
275
275
L'75
275
275
27 5
275
275
(L/s) (pCi/L)
0.1 830
0.3 9 900
0.2 22 000
0.3 4 -100
0.1 730
1 270
0.2 1 900
0.2 1 800
0.2 5 700
0.2 1G0
0.3 1 700
0.5 2'J
0.3 200
0.4 G 200
0.2 290
0.3 1 500
0.1 340
ron
0.5 3 400
0.2 I 300
21
COMMENTS
* 1 ei id wa 11
external
*2 rear wall
external
*3 roar i.ul 1
external
*1 front wall
external
*5 end wall
external
*6 cross wall
lnteinal
*7 front wall
external
*8 front wall
external
*9 fiont wall
external
* 10 cross wall
internal
*11 central
wall internal
*12 central
wall intern.il
*13 central
wall internal
*14 icar wall
exteri lal
*15 real wall
external
*16 rcir wall
external
*17 rear wall
external
* IS garage-
wan externa!
*19 gaiago
wall external
*20 front wall
external
at fan
Riser
-------
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LOW COST REDUCTION OF INDOOR RASON
FOUNDATION PLAN
Mitigation system: 5U&-5LA& ^LiCTlCSX
Dat®:
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