EPA/600/8-90/072
October 1990'
SUMMARY OF EPA's RADON REDUCTION RESEARCH
IN SCHOOLS DURING 1989-90
by:
Kelly W. Leovic
Radon Mitigation Branch
Air and Energy Engineering Research Laboratory
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
AIR AND ENERGY ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AM) DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NC 27711'
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TECHNICAL REPORT DATA _
fPkasc readInu/vciions on The reverse before compfe^
\. REPORT NO, __ . 2.
EPA/600/8-90/072
3i PB 91-10 203-8 j
V ¦ J
4. TITLE AND SUBTITLE
Summary of EPA's Radon Reduction Research in
Schools During 1989" 90
5. REPOHT DATE
October 1990
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Kelly W, Leovie
0. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
See Block 12
10. PROGRAM ELEMENT NO.
11. CUNT HACT/UHANT NO. •
NA (Inhouse)
12, SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Air and Energy Engineering Research Laboratory
Research-Triangle Park, North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
Project report; 1-9/90
14. SPONSORING AGENCY CODE
EPA/600/13
is. supplementary notes _£EERL project .officer is Kelly W, Leovie, Mail Drop 54, 919/
541-7717. |
\ I
is. ABSTHACT>^e rep0rt details radon mitigation research in schools conducted by EPA
during 1989 and part of 1990. The major objective was to evaluate the potential of ac-
tive sub slab depressurization (ASD) in various geologic and climatic regions. The
different geographic regions also presented a variety of construction types and heat-
ing, ventilating, and air-conditioning (HVAC) system designs that are encountered in
radon mitigation of school buildings. A secondary objective was to initiate research
in difficult-to-mitigate schools. This research led to the following major conclusions
on radon diagnostics and mitigation in schools: (1) Schools have many physical charac-
teristics that typically make their mitigation more complex than house mitigation, in-
cluding building size and substructure, subslab barriers, HVAC systems, a.nd loca-
tions of utility lines. (2) Important school diagnostic procedures and measurements
include review of radon measurements and building plans, investigation of the build-
ing to assess potential radon entry routes and confirm information in the building
plans, analysis of the HVAC system and its influence oil pressure differentials and
radon levels, and subslab pressure field extension measurements to determine the
potential applicability of ASD. (3) ASD can be applied successfully in schools where
subslab communication barriers are limited. ,
1?. KEY WORDS AND DOCUMENf ANALYSIS
1. DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
o. COS ATI Field/Group
Pollution
Radon
School Buildings
Slabs
Pressurizing
Ventilation
Pollution Control
I
Stationary Sources
HVAC Systems
Subslab Depressurizatior
13 B
07B
13 M, 051
13 C
14 G
13 A
18. DISTRIBUTION STATEMENT
Release to Public
10. SECURITY CLASS (This Report/"
Unclassified
.2.1 ..NO. OF PAGES
20. SECURITY CLASS (This page)
Unclassified
22, PRICE
EPA Form 2220-1 <3-73>
i
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ABSTRACT
This report details the radon mitigation research in school
buildings conducted by EPA's Air and Energy Engineering Research
Laboratory's (AEERL) Radon Mitigation Branch during 1989 and part
of 1990. Three schools in Alabama, three in Maryland, one in New
York, and six in Tennessee were selected for these research
ysv'Ai nr JL. «Lt If* JkHT X. w 1 fc£ Vin~ iMtf jp
various levels of diagnostics were performed in the different
schools,
In the Maryland, New York, and two of the Tennessee schools,
the mitigation systems were generally installed by the joint
efforts of an EPA Contractor, EPA personnel, and school personnel
following diagnostics and mitigation system design by EPA personnel
and/or their contractor. In the Alabama schools and in four of the
Tennessee schools, recommended mitigation system designs were
provided to the schools for installation by school personnel. The
diagnostics and mitigation for each of the 13 schools are discussed
separately and organized into sections by state.
The major objective of these school research projects was to
evaluate the potential of active subslab depressurization (ASD) in
varied geologic and climatic regions. The different geographic
regions present a variety of construction types and heating,
ventilating, and air-conditioning (HVAC) system designs. Another
objective was to initiate research efforts in difficult-to-mitigate
schools. Three schools previously identified in initial research
efforts in 1988 were selected to address this objective. Specific
"difficult" characteristics included schools with very poor subslab
communication limiting the application of ASD, schools with return-
air ductwork located beneath the slab, schools with utility
tunnels, and schools constructed over crawl spaces.
NOTICE
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
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CONTENTS
Page
ABSTRACT . ii
FIGURES • • • • ........... vii
TABLES xiv
ACKNOWLEDGEMENTS xvi
METRIC CONVERSION FACTORS xvii
SECTION 1. INTRODUCTION 1
1.1 Background 1
1.2 Objectives 1
1.3 Approach 1
SECTION 2. SUMMARY AND CONCLUSIONS . 3
SECTION 3. DIAGNOSTIC MEASUREMENT TECHNIQUES 5
3.1 Review of Radon Screening and Confirmatory
Measurements 5
3.2 Review of Building Plans 5
3.3 Building Investigation 6
3.4 HVAC System and Pressure Differentials ...... 6
3.5 Subslab Pressure Field Extension (PFE)
Measurements 8
3.6 Measurement of Subslab Radon Levels 9
SECTION 4. ALABAMA SCHOOLS 10
4.1 School A 11
4.1.1 Building Description 11
4.1.2 Pre-Mitigation Radon Measurements 11
4.1.3 Building Investigation 11
4.1.4 HVAC System and Pressure Differentials ...... 12
4.1.5 Diagnostic Measurements 12
4.1.6 Mitigation Strategy 14
4.1."7 ASD System Details .......................... 14
4.1.8 Estimated Cost 15
4.1.9 Summary 15
4 . 2 School B 15
4.2.1 Building Description 15
4.2.2 Pre-Mitigation Radon Measurements 16
4.2.3 Building Investigation 16
4.2.4 HVAC System and Pressure Differentials ...... 17
4.2.5 Diagnostic Measurements 17
4.2.6 Mitigation Strategy 18
4.2.7 Estimated Cost 19
4.2.8 Summary 19
iii
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Contents (Cont.)
Page
4.3 School C 19
4.3.1 Building Description 19
4.3.2 Pre-Mitigation Radon Measurements 20
4.3.3 Building Investigation 20
4.3.4 HVAC System and Pressure Differentials ...... 20
4.3.5 Diagnostic Measurements 21
4.3.6 Mitigation Strategy 21
4.3.7 Estimated Cost 22
4.3.8 Summary 22
SECTION 5. MARYLAND SCHOOLS 23
5.1 School D 23
5.1.1 Building Description 23
5.1.2 Pre-Mitigation Radon Measurements 23
5.1.3 Building Investigation 24
5.1.4 HVAC System and Pressure Differentials ...... 24
5.1.5 Diagnostic Measurements 24
5.1.6 Mitigation Strategy 25
5.1.7 Results of Initial Mitigation System 25
5.1.8 Second Phase of Mitigation and Results 2 6
5.1.9 Third Phase of Mitigation and Results 2 6
5.1.10 Final Radon Levels 27
5.1.11 Estimated Cost 27
5.1.12 Summary 27
5.2 School E 28
5.2.1 Building Description 28
5.2.2 Pre-Mitigation Radon Measurements 28
5.2.3 Building Investigation 28
5.2.4 HVAC System and Pressure Differentials 28
5.2.5 Diagnostic Measurements 29
5.2.6 Mitigation Strategy 23
5.2.7 Results of Initial Mitigation System 29
5.2.8 Second Phase of Mitigation and Results 3 0
5.2.9 Fma1 Radon Levels 30
5.2.10 Estimated Cost 3 0
5.2 .11 Summary ..................................... 30
5.3 School F 31
5.3.1 BixlIdDescrijloit ........................ 31
5.3.2 Pre-Mitigation Radon Measurements 31
5.3.3 Building Investigation 31
5.3.4 HVAC System and Pressure Differentials 31
5.3.5 Diagnostic Measurements ...... 32
5.3.6 Mitigation Strategy 32
5.3.7 Results of Initial Mitigation System ........ 32
5.3.8 Second and Third Phases of Mitigation and
Final Radon Levels 32
5.3.9 Estimated Cost 33
5.3.10 Summary 33
iv
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Contents (Cont.)
Page
SECTION 6. NEW YORK SCHOOL/SCHOOL G 34
6.1 Building Description 3 4
6.2 Pre-Mitigation Radon Measurements 34
6.3 Building Investigation 35
6.4 HVAC System and Pressure Differentials ...... 35
6.5 Diagnostic Measurements 36
6.6 Mitigation Strategy . . 36
6.7 Results of Initial Mitigation System 37
6.8 Additional Diagnostic Measurements 38
6.9 Summary 39
SECTION 7
TENNESSEE SCHOOLS 40
7.1 School H i
7.1.1 Building Description
7.1.2 Pre-Mitigation Radon Measurements .....
7.1.3 Building Investigation .............. ..
7.1.4 HVAC System and Pressure Differentials
7.1.5 Diagnostic Measurements
7.1.6 Mitigation Strategy
7.1.7 Results of Initial Mitigation System
7.1.8 Additional Phases of Diagnostics and
Mitx^ci^vion ...........................i
9 Final Radon Levels
10 Estimated Cost ,
11 SviituHary ..............................
7.1.
7.1.
7.1.
7.2
7.2,
7.2.
7.2.
School I
1 Building Description
2 Pre-Mitigation Radon Measurements
3 Building Investigation
7.2.4 HVAC System and Pressure Differentials
7.2.5 Diagnostic Measurements •*.••»*##¦••••<
7.2.6 Mitigation Strategy
7.2.7 Results of Initial Mitigation System
7.2.8 Additional Phases of Diagnostics and
Mitigation ............................
7.2.9 Fma1 Radon Levels •••••••••• *.«.*«•••!
7.2.10 Estimated C#c5S*t
7.2.11 Summary
40
40
41
42
43
44
46
47
49
51
51
52
52
52
53
54
54
55
56
57
58
59
59
59
7.3 School J
7.3.1 Building Description
7.3.2 Pre-Mitigation Radon Measurements
7.3.3 Building Investigation
7.3.4 HVAC System and Pressure Differentials
7.3.5 Diagnostic Measurements
7.3.6 Mitigation Strategy
7.3.7 Estimated Cost
7.3.8 Summary
60
60
60
61
62
62
63
64
64
V
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Contents (cont.)
Number Page
7 . 4 School K 64
7.4.1 Building Description 64
7.4.2 Pre-Mitigation Radon Measurements 64
7.4.3 Building Investigation 65
7.4.4 HVAC System and Pressure Differentials 66
7.4.5 Diagnostic Measurements 66
7.4.6 Mitigation Strategy 67
7.4.7 Estimated Cost 68
7.4.8 Summary 68
7 .5 School L 69
7.5.1 Building Description 69
7.5.2 Pre-Mitigation Radon Measurements 70
7.5.3 Building Investigation 70
7.5.4 HVAC System and Pressure Differentials 71
7.5.5 Diagnostic Measurements 71
7.5.6 Mitigation strategy 72
7.5.7 Estimated Cost 7 3
7.5.8 Summary 73
7.6 School M .... 73
7.6.1 Building Description 73
7.6.2 Pre-Mitigation Radon Measurements 74
7.6.3 Building Investigation 74
7.6.4 HVAC System and Pressure Differentials ...... 75
7 . . 5 i S i 5U3^ 65 ii ^ A i't S* ....... ....... ....... 75
7.6.6 Mitigation Strategy 76
7.6.7 Estimated Cost 77
7.6.8 Summary 77
SECTION 8. QUALITY CONTROL AND QUALITY ASSURANCE 79
8.1 Introduction 79
8.2 Quality Assurance Project Plan 79
8.3 Charcoal Canister Measurements 79
8.3.1 Assessment of Precision 80
8.3.2 Assessment of Accuracy 80
8.3.3 Assessment of Completeness 80
8.4 Continuous Radon Monitors 80
8.4.1 Assessment of Precision ..................... 81
8.4.2 Assessment of Accuracy 81
8.5 Audits 81
SECTION 9 . REFERENCES 82
APPENDIX A. FIGURES A-l
APPENDIX B. TABLES B-l
vi
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FIGURES
Number
Pacre
4.1.1
Floor plan showing additions at School A
A-2
4.1.2
June 1989 follow-up measurements, School A,
A-3
pCi/L
4.1.3
Location of canister numbers for CC measurements
A-4
in School A
4.1.4
Results of October 1989 CC measurements with HVAC
A-5
off in School A, pCi/L
4.1.5
Location of thickened slab footings in School A
A-6
4.1.6
Location of soil sample sites for radium analysis
A-7
at School A
4.1.7
Location of suction and test points used in
A-8
subslab communication tests in School A
4.1.8
On Kc? 1 a K v>a /-3 ati 4- nnc m o a t?nMaxrcmK/av
oujjsxgljp JTciQOJi concentrations measureu ±n jnoveiuDeir
A-9
1989 in School A, pCi/L
4.1.9
Comparison of room radon levels with levels under
A-10
the slab in School h, November 1989, pCi/L
4.1.10
Subslab pressure field measured from SP #1 in
A-11
School A
4.1.11
Subslab pressure field measured from SP #2 in
A-12
School A
4.1.12
Subslab pressure field measured from SP #3 in
A-13
School A
4.1.13
Subslab pressure field measured from SP #4 in
A-14
School A
4.1.14
Subslab pressure field measured from SP #5 in
A-15
School A
4.1.15
Approximate pressure field extension measured
A-16
from suction points 1 through 5 in School A
4.1.16
Suggested ASD mitigation system, School A
A-17
4.1.17
Subslab suction point details
A-18
4.2.1
Floor plan showing additions, room numbers, and
A-19
subslab details at School B
4.2.2
Results of June 1989 follow-up CC measurements,
A-2 0
School B, pCi/L
4.2.3
Location of canister numbers for CC measurements
A-21
in School B
4.2.4
Results of October 1989 CC measurements in
A-22
School B
4.2.5
Location of soil sample sites for radium
A-2 3
analysis at School B
4.2.6
Location of suction and test points used in
A-24
subslab communication tests at School B
4.2.7
Subslab radon concentrations measured in
A-2 5
November 1989 at School B
4.2.8
Comparison of room radon levels with levels
A-2 6
under the slab in School B
4.2.9
Subslab pressure field measured from SP #1,
A~2 7
School B
vii
-------
Figures (Cont.)
Number Pacre
2.10 Subslab pressure field measured from SP #2, A-28
School B
2.11 Subslab pressure field measured from SP #3, A-29
School B
2.12 Subslab pressure field measured from SP #4, A-30
School B
2.13 Subslab pressure field measured from SP #5, A-31
School B
2.14 Approximate pressure field extension measured A-32
from SP #s 1-5, School B
4.2.15 Suggested mitigation system for School B A-33
4.3.1 Basement floor plan and room numbers in School C A-34
4.3.2 Results of two-day CC measurements over the periods A-35
3/28-30/90 and 4/10-12/90 in School C, pCi/L
3.3 Subslab communication test locations and results A—36
measured on 11/3/89 in School C
3.4 Subslab radon levels in pCi/L measured on 11/3/89 A-37
in School C
4.3.5 Estimated pressure field extension from suction A-38
test point Fa in School C
4.3.6 Estimated pressure field coverage with proposed A-39
mitigation system in School C
4.3.7 Proposed mitigation system for School C A-40
5.1.1 Pre-mitigation radon levels in School D, pCi/L A-41
5.1.2 CRM results for School D A-42
5.1.3 Radon levels with ASD and tunnel depressurization A-43
systems in operation in School D, pCi/L
5.1.4 HVAC on, exhaust fans on, ASD off, School D A-44
5.1.5 CRM results in School D with utility tunnel A-45
depressurization fan on and off (9/27 - 10/11/89)
5.2.1 CRM results for School 1 A-46
5.2.2 Crawl space depressurization in School E with fan A-47
on and off (12/22/88 - 1/7/89)
5.3.1 Floor plan of School F with radon levels A-48
5.3.2 School F radon levels in pods A-49
6.1 School G basement area pre-mitigation radon A-50
measurements using activated charcoal canisters.
Monitoring period (10/7 - 9/89). School unoccupied.
6.2 School G basement area pre-mitigation radon A-51
measurements using activated charcoal canisters.
Monitoring period (12/8 - 10/89). School occupied.
6.3 School G basement area pre-mitigation radon A-52
measurements using activated charcoal canisters.
Monitoring period (12/11 - 13/89). School
unoccupied.
6.4 School G basement area subslab radon levels A-53
6.5 School G basement area subslab communication A-54
testing locations
viii
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Figures (Contd.)
Number Page
6.6 School G basement subslab depressurization system A-55
layout
6.7 School G office CRM pre-mitigation radon A-56
concentrations. Monitoring period: 12/14 - 28/89
6.8 School G office CRM post-mitigation radon a-57
concentrations. Monitoring period: 1/26 - 2/23/90
6.9 School G basement area post-mitigation radon A-58
measurements using activated charcoal canisters
Monitoring period 2/12 - 14/90'
6.10 Subslab pressures at distances with respect to A-59
penetration point 1, with and without suction pits
in School G
6.11 Comparison of pipe pressures in School G A-60
6.12 School G basement area radon measurements using A-61
activated charcoal canisters. Monitoring period
3/13 - 15/90
6.13 School G basement office post-mitigation radon A-62
concentrations. Monitoring period: 3/2 - 30/90
6.14 School G basement office radon concentrations with A-63
ASD system operating and outdoor air dampers for
basement unit ventilator open
6.15 School G basement office radon concentrations with A-64
ASD system operating and outdoor air dampers for
basement unit ventilator open and closed
7.1.1 Floor plan showing additions at School H A-65
7.1.2 Location of class rooms and measurement numbers A—66
for first floor, School H
7.1.3 Location of class rooms and measurement numbers A-67
for second floor, School H
7.1.4 February 1989 pre-mitigation CC measurements on A-68
first floor, School H
7.1.5 Follow-up CC measurements in March 1989 following A-69
sealing of entry holes by School H staff
7.1.6 Pre-mitigation CC and (E-perm) measurements in A-70
June 1989 on first floor of School H, pCi/L
7.1.7 Pre-mitigation CC and (E-perm) measurements in A-71
June 1989 on second floor of School H, pCi/L
7.1.8 Comparison of June 1989 CC measurements to the A-72
values measured in February 1989 at School H
7.1.9 Pre-mitigation subslab radon levels measured in A-73
June 1989 at School H
7.1.10 Comparison of room radon levels with levels under A-74
the slab at School H
7.1.11 Pre-mitigation subslab pressure field extension A-7 5
suction and test point locations at School H
7.1.12 Pre-mitigation pressure field extension in the A-76
North wing of School H, June 1989. Suction point
in closet of room 104
7.1.13 Pre-mitigation pressure field extension in the A-77
south wing of School H, June 1989. Suction point
in office of room 121
7.1.14 Pre-mitigation pressure field extension in the A-78
basement of School H, June 1989. Suction point
in art room.
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F igures (Cont.)
Number Page
7.1.15 Pro-mitigation subslab pressure field extension A-79
at School H, in. w.c.
7.1.16 Continuous radon levels measured in several rooms A-80
of School H
7.1.17 Post-mitigation CC and (E-perm) measurements in A-81
School H in June 1989 with temporary ASD systems
operating
7.1.18 Post-mitigation continuous radon monitor levels A-82
with temporary ASD systems operating in June 1989
at School H
7.1.19 Post-mitigation pressure field extensions using A-83
temporary ASD systems in June 1989 at School H
7.1.20 Pressure field extension using the temporary A-84
mitigation systems at School H
7.1.21 Pressure field extension using the permanent A-85
mitigation systems in School H
7.1.22 Post-mitigation field extensions in School H using A-86
permanent ASD systems in August 1989
7.1.23 Post-mitigation CC measurements in School H in July A-87
1989 with two permanent ASD systems operating, pCi/L
7.1.24 Post-mitigation CC measurement in August 1989 on A-88
first floor of School H, all three permanent
ASD systems operating, pCi/L
7.1.25 Post-mitigation CC measurements in August 1989 on A-89
second floor of School H, all three permanent ASD
systems operating, pCi/L
7.1.26 Post-mitigation CC measurements in December 1989 A-90
at School Hr pCi/L
7.1.27 Post-mitigation CC measurement results for January A-91
1989, School H, pCi/L
7.2.1 Floor plan of School I showing additions and dates A-92
7.2.2 Location of class rooms and measurement numbers for A-93
School I
7.2.3 February 1989 pre-mitigation and (follow-up) CC A-94
measurements at School I
7.2.4 June 1989 pre-mitigation CC measurements at A-9 5
School I
7.2.5 July 1989 pre-mitigation CC measurements at A-96
School I
7.2.6 Summary of pre-mitigation radon levels measured in A-97
School I by room number, part 1
7.2.7 Summary of pre-mitigation radon levels measured in A-98
School I by room number, part 2
7.2.8 Pre-mitigation subslab radon levels measured in A-99
School I in June 1989, pCi/L
7.2.9 Pre-mitigation subslab pressure field extension A-100
suction and test point locations at School I
7.2.10 Pre-mitigation pressure field extensions in A-101
School I in June 1989
7.2.11 Initial mitigation system design layout for A-102
School I
7.2.12 Continuous radon levels in Room 120 of School I A-103
x
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Figures (Cont.)
Number Page
7.2.13 Post-mitigation pressure field extensions in A-104
School I using the ASD mitigation systems
7.2.14 Post-mitigation CC measurements in School I in A-105
August 1989 with ASD systems operating, pCi/L
7.2.15 Summary of pre-mitigation (July 1989) and post- A-106
mitigation (August 1989) radon levels in School I
7.2.16 Post-mitigation CC measurements in School I in A-107
December 1989, pCi/L
7.2.17 Post-mitigation CC measurements in School I in A-108
January 1990, pCi/L
7.2.18 Final mitigation system configuration at School I A-109
7.2.19 Post-mitigation CC measurement results in School I A-110
in February 1990, pCi/L
7.3.1 Floor plan showing additions and subslab details A-lll
in School J
7.3.2 Location of canister numbers for CC measurements A-112
in School J
7.3.3 Results of February 1989 CC screening A-113
(and follow-up) measurements in School J, pCi/L
7.3.4 Results of July 1989 CC measurements in School J, A-114
pCi/L
7.3.5 Comparison of February and July 1989 CC A-115
measurements in School J
7.3.6 Location of suction and test points used in subslab A-116
communication tests in School J
7.3.7 Subslab radon concentrations measured in June 1989 A-117
in School J
7.3.8 Comparisons of February and July 1989 room A-118
radon data to subslab in June 1989 in School J
7.3.9 Subslab pressure fields measured in June 1989, A-119
School J
7.3.10 Proposed mitigation system for School J A-120
7.3.11 Additional detail for North-South mitigation A-121
system including basement rooms of School J
7.3.12 Typical sub-membrane depressurization system for A-122
crawl spaces
7.4.1 Floor plan showing additions and dates of School K A-123
7.4.2 Locations of room numbers in School K A-124
7.4.3 Location of canister numbers used for CC A-125
measurements, in School K
7.4.4 Results of February 1989 CC measurements (and A-126
follow-up) in School K, pCi/L
7.4.5 Results of July 1989 CC measurements in School K, A-127
pCi/L
7.4.6 Comparison of February and July 1989 CC A-128
measurements in School K
7.4.7 Location of suction and test points used in A-129
June 1989 communication tests in School K
7.4.8 Subslab pressure fields measurements in June 1989 A-130
in School K
7.4.9 Subslab radon concentrations measured in June 1989 A-131
in School K, pCi/L
7.4.10 Location of suction and test points used in July A-132
1989 communication tests in School K
xi
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Figures (Cant.)
Number Page
7.4.11 Subslab radon concentrations measured in July 1989 A-133
in School K, pCi/L
7.4.12 Comparison of February and July 1989 room radon A-134
levels to the subslab levels measured in July 1989
in School K
7.4.13 Subslab pressure field measured from suction point A-135
1 in School K
7.4.14 Subslab pressure field measured from suction point A-136
2 in School K
7.4.15 Subslab pressure field measured from suction point A-137
3 in School K
7.4.16 Subslab pressure field measured from suction point A-138
4 in School K
7.4.17 Summary of subslab pressure field extensions in A-139
School K
7.4.18 Proposed mitigation system for School K A-140
7.5.1 Floor plan showing additions and dates of School L A-141
7.5.2 Locations and extents of the utility tunnel in A-142
School L
7.5.3 Locations of room and canister numbers used in CC A-143
measurements in School L
7.5.4 Results of February 1989 and follow-up CC A-144
measurements, School L, pCi/L
7.5.5 Results of June 1989 CC measurements in A-145
School L, pCi/L
7.5.6 Comparison of February and June 1989 CC A-146
measurements in School L
7.5.7 Location of suction and test points used in A-147
June/July 1989 communication tests in School L
7.5.8 Subslab radon concentrations measured in June/July A-148
1989 in School L, pci/L
7.5.9 Comparison of February and June 1989 room radon A-149
levels to the subslab levels measured in June/July
1989 in School L
7.5.10 Comparison by location of the February 1989 room A-150
and June/July 1989 subslab radon levels in School L
7.5.11 Comparison by location of the June 1989 room and A-151
June/July 1989 subslab radon levels in School L
7.5.12 Subslab pressure field measured in June 1989 A-152
from suction point 1 in School L
7.5.13 Subslab pressure field measured in June 1989 A-153
from suction point 2 in School L
7.5.14 Subslab pressure field measured in June 1989 A-154
from suction point 3 in School L
7.5.15 Subslab pressure field measured in June 1989 A-155
from suction point 4 in School L
7.5.16 Summary of July 1989 pressure field extensions A-156
in School L
7.5.17 Proposed mitigation system for School L A-157
7.5.18 Anticipated pressure field coverage using the A-158
proposed mitigation system in School L
7.6.1 Floor plan showing additions and dates of School M A-159
XII
-------
Figures (Cont.)
Number Page
7.6.2 Locations of room and canister numbers used in GC A-160
measurements in School M
7.6.3 Results of February 1989 screening (and follow-up) A-161
CC measurements in School M, pCi/L
7.6.4 Results of July 1989 CC measurements in School M A-162
7.6.5 Comparison of February and July 1989 CC A-163
measurements in School M
7.6.6 Correlation of February and July 1989 CC A-164
measurements in School M
7.6.7 Location of suction and test points used in July A-165
1989 subslab communication tests in School M
7.6.8 Subslab radon concentrations measured in July 1989 A-166
in School M, pCi/L
7.6.9 Comparison of February and July 1989 room radon A-167
levels to the subslab levels measured in July 1989
in School M
7.6.10 Subslab pressure field measured in July 1989 from A-168
suction point 1 in School M
7.6.11 Subslab pressure field measured in July 1989 from A-169
suction point 2 in School M
7.6.12 Subslab pressure field measured in July 1989 from A-170
suction point 3 in School M
7.6.13 Subslab pressure field measured in July 1989 from A-171
suction point 4 in School M
7.6.14 Subslab pressure field measured in July 1989 from A-172
suction point 5 in School M
7.6.15 Summary of July 1989 subslab pressure field A-173
extensions in School M
7.6.16 Proposed mitigation system for School M A-174
8.3.1 Standard deviation as a function of the average A-175
collocated CC measurements
xiii
-------
TABLES
Number Page
4.1.1 School A data summary B-2
4.2.1 School B data summary B-3
6.1 Statistical analysis of activated charcoal B-4
measurements performed in basement area of
school G, October 7-9, 1989
6.2 Frequency distribution of activated charcoal B-4
woaeiTrowon+'e ndY"?Aywuafi i n K^a6'l!l,larl^^• ayiAa aF
jliiGS d inw^ Imh Jl fc5 livC* J 1 v S3 t*JL JL Mm JL i 1. «p*/CIp i!wi fcJ*11x2-111 Im* CtlJL> C* d JL»
School G, October 7-9, 1989
6.3 Statistical analysis of activated charcoal B-5
measurements performed in basement area of
School G, December 8-10, 1989
6.4 Frequency distribution of activated charcoal B-5
measurements performed in basement area of
School G, December 8-10, 198 9
6.5 Statistical analysis of activated charcoal B-6
measurements performed in basement area of
School G, December 11-13, 1989
6.6 Frequency distribution of activated charcoal B-6
measurements performed in basement area of
School G, December 11-13, 19B9
6.7 Results of subslab communication testing in B-7
School G
6.8 Statistical analysis of hourly pre-mitigation B—8
radon concentrations in Office #4 of School G
6.9 Frequency distribution of hourly pre-mitigation B-8
radon concentrations in Office #4 of School G
6.10 Statistical analysis of hourly radon B-9
concentrations with subslab depressurization
system in passive mode in School G
6.11 Frequency distribution of hourly radon B-9
concentrations with subslab depressurization
system in passive mode in School G
6.12 Statistical analysis of hourly radon B-10
concentrations with ASD system in active mode
in School G
6.13 Frequency distribution of hourly radon B-10
concentrations with ASD system in active mode
in School G
6.14 Statistical analysis of post-mitigationll B-ll
activated charcoal measurements performed in
basement area of School G, February 12-14, 1989
6.15 Frequency distribution of post-mitigation B-ll
activated charcoal measurements performed in
basement area of School G, February 12-14, 1989
6.16 Statistical analysis of post-mitigation B-12
activated charcoal measurements performed in
basement area of School G, March 13-15, 1989
xiv
-------
Tables (Cont.)
Number Page
6.17 Frequency distribution of post-mitigation B-12
activated charcoal measurements performed in
basement area of School G, March 13-15, 1989
7.1.1 Radon concentrations measured at school H B-13
7.1.2 Pre-mitigation subslab communication test data, B-18
part 1, School H
7.1.3 Pre-mitigation subslab communication test data, B-19
part 2, School H
7.1.4 Pre-mitigation subslab communication test data, B-20
part 3, School H
7.1.5 Post-mitigation subslab communication data B-21
with temporary system part 1, School H
7.1.6 Post-mitigation subslab communication data B-22
with temporary system part 2, School H
7.1.7 Post-mitigation subslab communication data B-23
with temporary system part 3, School H
7.1.8 Post-mitigation subslab communication data B-24
with temporary system part 4, School H
7.1.9 Post-mitigation subslab communication data B-25
withpermanent system part 1, School H
7.1.10 Post-mitigation subslab communication data B-26
with permanent system part 2, School H
7.1.11 Post-mitigation subslab communication data B-27
with permanent system part 3, School H
7.1.12 Post-mitigation subslab communication data B-28
with permanent system part 4, School H
7.1.13 Estimated material costs and work-hour B-29
expenditure for mitigation of School H
7.2.1 Radon concentrations measured at School I B-30
7.2.2 Pre-mitigation subslab communication test data,
part 1, School I B-3 5
7.2.3 Pre-mitigation subslab communication test data,
part 2, School I B-36
7.2.4 Pre—mitigation subslab communication test data,
part 3, School X B-37
7") K T)vfl"i *4 4 aw c?nV\es 1 a K nrvwffliin i ria4" i An 4*c4*
* b * «> xrJETXuJL *»d XQ*1 oUxJS JLCaO wUlTlXriUXi XIvd w J.U11 vv& vJd wci f
part 4, School I B-38
7.2.6 Estimated material costs and work-hour
expenditure for mitigation of School I B-39
7.3.1 School J radon measurements B-40
7.4.1 School K radon measurements B-41
7.5.1 School L radon measurements B-4 2
7.6.1 School M radon measurements B-43
8.3.1 Collocated duplicate charcoal canister results B-44
8.3.2 Average of all collocated CC results grouped B-48
by state
xv
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ACKNOWLEDGEMENTS
The author would like to express her sincere thanks to the
following contractors who contributed substantially to this report:
Bobby E. Pyle of Southern Research Institute (under EPA Contract 68-02-
4287, Work Assignments 009, 014, and 018) for his extensive efforts in
conducting the research and preparing the reports for the Alabama and
Tennessee Schools; Mike Clarkin of Camroden Associates (under EPA
Purchase Order 0DO3 00NASA) for conducting the research and preparing the
report for the New York School; and David W. Saura of Infiltec (under EPA
Purchase Order 0D0362NAST)for conducting the research in the Maryland
Schools.
The author would also like to express her appreciation to; the
school personnel who allowed us to conduct research in their buildings
for their assistance in making radon measurements, conducting diagnostic
measurements, and, as applicable, installing radon mitigation systems;
AEERL's A. B, Craig for initiating the contacts with many of these
school personnel, for assistance xn conducting the fxeld measurements,
and for peer reviewing this report; AEERL's D. B. Harris and A. W.
Fowler, Acurex's Felton Perry and Southern Research Institute's Ray
Coker for their extensive efforts in conducting radon measurements,
diagnostics, and installing mitigation systems; Susie Shimick and
Jackie Waynick of the Tennessee Department of Health and Environment for
assisting in radon measurements and diagnostics; Craig Kneeland and Mark
Watson of the New York State Energy Office for assisting in radon
diagnostics and mitigation; and Paul Wagoner of EPA Region 4 for peer
reviewing this report.
xv i
-------
METRIC CONVERSION FACTORS
Although it is EPA policy to use metric units in its documents,
non-metric units have been used in this report to be consistent with
common practice in the radon mitigation field. Readers may refer to the
following factors to convert to that system.
NON-METRIC
British thermal unit (Btu)
cubic foot (cu ft)
cubic feet per minute (cfm)
degree Fahrenheit (°F)
foot (ft)
gallon (gal.)
horsepower (hp)
inch (m•)
inch of water column (in. WC)
mil (0.001 in.)
mile (mi)
picoCurie per liter (pCi/L)
TIMES
105
28. 3
0.47
5/9 (°F-32)
0. 305
3.79
746
2 . 54
248
25.4
1.61
37
YIELDS METRIC
joules (J)
liters (L)
liter per second (L/s)
degrees Centigrade (°C)
meter (m)
liters (L)
watts (W)
centimeters (cm)
pascals (Pa)
micrometers (um)
kilometers (km)
becquerels per cubic
meter (Bq/m3)
square foot (sq ft)
0.093
square meter (m2)
xvii
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SECTION 1
INTRODUCTION
1.1 BACKGROUND
The U.S. Environmental Protection Agency (EPA) initially became
involved with the radon problem in schools by assisting three counties
in Maryland and Virginia in reducing elevated levels of radon in 1988.
This cooperative effort between the EPA and the school districts
resulted in the successful mitigation of radon levels in seven schools.
Active subslab depressurization (ASD) — a technique which had been
demonstrated successfully in existing houses — was modified and
installed in these schools. Where design permitted, heating,
ventilating, and air-conditioning (HVAC) systems were also used to
pressurize some of the school buildings to control radon levels prior to
installation of the ASD system. These initial efforts are detailed as
case studies in the EPA document Radon Reduction Techniques in Schools -
Interim Technical Guidance (1) .
In 1989 and early 1990, EPA's Radon Reduction Research/Development/
Research/Development/Demonstration Program in schools was expanded to
include projects in Alabama, New York, and Tennessee, and research in
some of the Maryland schools continued. These projects were initiated
to address the objectives discussed below.
1.2 OBJECTIVES
The initial research efforts in a limited number of Maryland and
Virginia schools confirmed the applicability of ASD in schools that had
slabs that were underlain with a clean layer of clean coarse aggregate
to facilitate subslab communication. The major objective of the
subsequent research projects discussed in this report was to apply ASD
in varied geologic and climatic regions. The different geographic
regions would also present a variety of construction types and HVAC
system designs. The details of each of the objectives are expanded in
each case study.
Another objective of the project was to initiate research efforts
in "diff icult-to-mitigate" schools. Three schools that had been
identified in the initial research efforts in Maryland in 1988 were
selected for additional research. Specific characteristics addressed
included schools with very poor subslab communication limiting the
application of ASD, schools with return-air ductwork located underneath
the slab, schools with utility tunnels, and schools constructed over
crawl spaces.
1.3 APPROACH
Three schools in Alabama, three in Maryland, one in New York, and
six in Tennessee were selected for these research projects. The work in
1
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the Alabama and Tennessee schools was performed by southern Research
Institute and EPA personnel; the work in Maryland was performed by
Infiltec and EPA personnel; and the work in New York was performed by
Camroden Associates and EPA personnel. Depending on the objectives of
the specific project, various levels of diagnostics and mitigation were
performed in the different schools. in the Maryland, New York, and two
Tennessee schools, the mitigation systems were generally installed by
the joint efforts of the EPA contractor, EPA personnel, and school
personnel following diagnostics and mitigation system design by EPA
personnel and/or their contractor. In the Alabama schools and in four
of the Tennessee schools mitigation system designs were provided to the
schools for installation by school personnel.
The diagnostics and mitigation for each of the 13 schools are
discussed separately and organized into sections by state. As
applicable, discussion of each school is organized into the following
sub-sections: 1) Background Information, 2) Building Description, 3)
Fre-Mitigation Radon Measurements, 4) Building Investigation, 5) HVAC
System, 6) Diagnostic Measurements, 7) Mitigation Strategy, 8) ASD
Systems Details, 9) Results of Initial Mitigation System, 10) Additional
Phases of Diagnostics/Mitigation, 11) Final Radon Levels, 12) Estimated
Cost, and 13) Summary.
The city and state of each school are provided in the report.
2
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SECTION 2
SUMMARY AND CONCLUSIONS
Based on the radon diagnostics and mitigation conducted in 13
schools, located in the states of Alabama, Maryland, New York, and
Tennessee, the following conclusions on radon diagnostics and mitigation
in schools can be made:
1) School buildings have a number of physical characteristics that make
their mitigation different, and typically more complex, than houses.
These characteristics include: building size and substructure, subslab
barriers, heating, ventilating, and air-conditioning (HVAC) systems, and
locations of utility lines. These physical characteristics can
influence radon levels in the building since they affect radon entry
routes, building pressure differentials, and radon mitigation approach.
2) Radon measurements in schools can vary dramatically over time
(seasonally and diurnally), and this variation must be considered when
conducting radon diagnostics and designing mitigation systems.
3) Radon mitigation research in schools has shown that the following
diagnostics procedures and measurements are important in understanding
a school's radon problem and potential solution: review of radon
measurements; review of building plans including structural, mechanical,
plumbing, and electrical; investigation of the school building to assess
potential radon entry routes and conf irm information cited in the
building plans; analysis of the HVAC system and its influence on
pressure differentials and radon levels; and performance of subslab
Pressure Field Extension (PFE) measurements,
4) Active subslab depressurization (ASD) can be applied successfully in
schools where the slab is underlain with a clean coarse layer of
aggregate of narrow particle size range as long as subslab barriers to
communication are limited.
5) ASD in schools typically requires greater fan capacities and suction
pipe diameters than does ASD in houses. The capacities of the fans used
(or recommended) in these school installations were typically around 310
cfm (at 0.75 in. WC) compared to capacities of about 150 cfm (at 0.75
in. WC) for fans commonly installed in house ASD systems. In schools
where the slab was underlain with at least a 4 in. layer of clean,
coarse aggregate enhancing subslab air flow, fan capacities of about 470
cfm (at 0.75 in. WC) were often installed. Suction pipe diameters used
(or recommended) in these ASD systems were typically 4 in. or greater,
compared to 4 in. or less in typical house ASD systems.
6) If all block walls surrounding the classrooms extend to footings
creating subslab barriers (or compartments), it is necessary to have one
ASD point for every two rooms and, in many cases, one point for each
room. If the walls between rooms are set on thickened slab footings
rather than on below-grade walls, ASD from one point will extend under
3
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the thickened slab especially if the aggregate is continuous underneath.
PFE measurements will provide essential data on the nature and extent of
subslab barriers and implications for ASD system design.
7} In general, the correlation between class room radon concentrations
and subslab radon "sniffs" was not particularly good.
8) h majority of the schools studied thus far include slab-on-grade
substructures, although some of the schools had portions with basement
and/or crawl space substructures.
9) HVAC systems in the schools studied thus far include unit
ventilators, fan coil units, radiant heat, and central-air handling
systems. Many of the schools are not designed wxth the capability to
deliver conditioned outdoor* air t*o tliA flrcunied csiiArp a
v* w JL -i- V CJL, w wl v -JL Wi W U LUUU1 u JL JL WW WJ>l»w www UJJ XCU i3l|JQVC • il 13 Q JL w w U. JL w f
radon control through the existing HVAC system was often not a
mitigation option. Increasing the outdoor air supply in schools could
reduce the driving force for radon entry.
10) Many of the slab-on-grade schools run their utility lines in
subslab utility tunnels. It may be possible to reduce radon levels by
depressurizing these tunnels; however, many of them contain asbestos,
limiting the feasibility of this approach.
4
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SECTION 3
DIAGNOSTIC MEASUREMENT TECHNIQUES
School buildings have a number of physical characteristics that
make them different, and typically more complex, than residential
houses. These characteristics include: building size, substructure,
subslab barriers, HVAC system design and operation, and locations of
utility lines. These physical characteristics can influence radon
levels in the building since they affect radon entry routes, building
pressure differentials, and radon mitigation approach.
The radon diagnostic procedures for school buildings discussed
below include: a review of all radon screening and confirmatory
measurements; a review of all available building plans and
specifications including structural, mechanical, and electrical; a
thorough building investigation to assess potential radon entry routes
9 /-J +*n riAfii" i >"tpi anH 4" a en rkr\ 1 atta n 4" 4 ri *f a vm at* i at* /""n t 4~ /•> 4- V* /-* Vvi i *5 1 i*l i *"» ft
ui 1U L>U wwX1 ^ XX 1U ellw w & LL^/^Xciltcf 11 Xiii. CJ X. lllcL wX wi 1 v X wC»U JLX1 wXl*>3 UU JL JLUXflu
plans; an analysis of the HVAC system design and operation and its
influence on pressure differentials and radon levels; and measurements
of subslab radon levels and recommended techniques for measuring subslab
Pressure Field Extension (PFE) to assess the potential for an ASD
system.
Depending on the specific objectives of each project, varying
levels of diagnostics were performed in the schools discussed in this
report. The discussion below is intended to be all-inclusive.
3.1 REVIEW OF RADON SCREENING AND CONFIRMATORY MEASUREMENTS
Initial radon screening, confirmatory measurements, and any
additional measurements followed EPA's interim radon measurement
protocol as closely as possible unless modified to determine the effects
of specific variables (2). The measurement results were written on a
copy of the school floor plan, along with a description of measurement
conditions. Potentially important measurement conditions include:
operational status of HVAC system(s), weather (outdoor temperature,
precipitation, wind, barometric pressure, etc.), and occupied or
unoccupied status.
3.2 REVIEW OF BUILDING PLANS
Ideally, all building plans and specification documents were
obtained for review. (Note: such plans are not always available.)
Pertinent drawings include architectural, structural, mechanical, and
electrical. The following summarizes the pertinent information
typically provided by these plans.
The architectural drawings will give general information on
building design and also provide details on typical wall sections.
The structural drawings will contain information on the foundation,
5
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footing and thickened slab footing locations, and subslab fill. These
will be helpful to assess the potential effectiveness of an ASD system
by indicating the presence, size, and thickness of subslab aggregate and
any barriers to subslab communication such as below-grade walls. The
structural drawings may also provide clues to possible radon entry
routes such as expansion joints and pipe chases.
The mechanical drawings and specifications will provide information
on the HVAC system design (such as duct system design, location, duct
run length, supply/return air flow design capacity, outdoor air intakes,
and exhaust systems). The mechanical specifications should summarize
the HVAC system and identify equipment. For schools with intra-slab
radiant heat systems, the plans are particularly important in locating
subslab piping prior to measuring subslab communication. Where
applicable, the balancing report should also be consulted. Note that 15
cfm of outdoor air per person is suggested for classrooms in the most
recent American Society of Heating, Refrigerating and Air-Conditioning
Engineers (ASHRAE) indoor air quality standard (3).
The plumbing and electrical drawings should initially be reviewed
for potential radon entry routes. If subslab communication is to be
measured to determine the potential for an ASD system, these plans must
be studied to determine the locations of subslab utility lines prior to
drilling test holes through the slab. Even if plumbing and/or
el ar't'T"! ria 1 1 i noe a>*o "fiiTi nnHor +-"ho cl a]*» yat/1 a*F +»1ncs nl ane t 4 1 1
c x€ w Wl. X vfl X JL J.*16b dJL C x Uii Ui lU."x L-im p JLaU f XT6 V JLcW wx wllw p xuilS W-L x x
usually reveal suitable locations for test holes.
3.3 BUILDING INVESTIGATION
A thorough building investigation was conducted to assess potential
radon entry routes and confirm information cited in the building plans
and specifications. Entry routes include floor/wall cracks, unsealed
{or deteriorated) expansion joints, utility penetrations, and open pores
of block walls or unsealed tops of block walls that penetrate the slab.
A chemical smoke stick was used to determine the direction of air
movement through potential entry routes, and a micromanometer was used
to determine the magnitudes of pressure differentials under various HVAC
system operational modes. A continuous radon monitor was used to
sample potential radon entry routes and subslab radon levels. For
schools discussed in this report, a Pylon AB-5 unit with a Lucas cell
operated in a sniffer mode was typically used to assess the relative
significance of suspected radon entry routes and sample subslab radon
levels. Observations made during the building investigation were
compared with the radon measurements and correlations noted.
3.4 HVAC SYSTEM AND PRESSURE DIFFERENTIALS
The HVAC system can have significant influences on pressure
differentials m a school building. Where possible, the school engineer
or other knowledgeable person(s) responsible for operation and
maintenance of the HVAC system were present during the analysis.
6
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The first step was to confirm information found in the mechanical
plans and specif1cations• Is the HVAC system actually installed and
operated as designed or, for example, have outdoor air intakes been
restricted thus reducing the ventilation capability controlled?
A chemical smoke stick was used to determine whether the building
envelope was pressurized or depressurized relative to the outdoors,
hallway, or subslab, and a micromanometer was used to quantify the
pressure differentials. When analyzing the pressure differentials
induced by the HVAC system, it was desirable that measurements were made
under "typical" operating conditions. Depending on the type of HVAC
system and the testing constraints of a given school district, these may
or may not be the same conditions under which screening and confirmatory
measurements were made. Attention was also paid to include all exhaust
fans that are not included as part of a central HVAC system.
If the HVAC system was a major contributor . to the negative
pressures in the building, was this a result of the HVAC system design
or was it due to operation and maintenance practices? If the system has
the design capacity to maintain all building zones under positive
pressure, it may be possible to control radon levels by adjustment of
the HVAC system by a qualified person. If HVAC pressurization is under
consideration as a permanent approach for radon control, the additional
operation and maintenance costs must be considered, and the school
maintenance personnel must thoroughly understand the proper system
operation and maintenance. Equipment and/or procedures to identify
inadequate HVAC operation are also important.
If it was suspected that radon was being distributed in the school
by the air-handling system (with a central HVAC system or unit
ventilators), radon "sniffs" in the supply air were compared with radon
levels in the room(s). Elevated levels of indoor radon caused by radon
entry into the return-air system and distribution to classrooms with
recirculated room air can result from, for example: leaky subslab return
air ductwork, unducted return-air plenums m the drop ceiling that are
open to the subslab via open tops of block walls extending through the
slab, and air intakes for unit ventilators that are open to the soil or
floor/wall joint.
Many schools have not been designed to supply conditioned outdoor
air to occupied spaces and, as a result, do not have the option for HVAC
pressurization with current system design. Typically with such schools
the fresh air was intended to be provided through above-grade shell
leakage and openings such as windows. However, many of these schools
have been retrofitted for energy conservation, decreasing the amount of
outdoor air infiltration from above grade. The lack of fresh outdoor
air as a result of these tightening measures can reduce dilution of the
indoor air and increase the driving forces which cause radon entry.
If schools operate an exhaust fan for ventilation purposes or to
remove odors or chemicals and sufficient makeup air is not supplied,
significant negative pressures can result. This will exacerbate radon
7
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entry into the building through below-grade cracks and openings.
3.5 SUBSLAB PRESSURE FIELD EXTENSION (PFE) MEASUREMENTS
Although the general principles of PFE measurements are similar to
those applied in house diagnostics, some circumstances and procedures
are specific to schools. The approaches outlined in Radon Reduction
Techniques in Schools - Interim Technical Guidance have been followed as
closely as possible (1), and a summary follows.
The first step in determining the potential effectiveness of a
school ASD system was analysis of the building plans to determine the
locations and types of subslab walls and footings and thickened slab
footings that may serve as barriers to subslab communication. The plans
typically indicated whether aggregate was called for beneath the slab.
It should be noted, however, that grading of aggregate is highly
variable and the indication of subslab aggregate on the plans did not
necessarily ensure good PFE. If the plans were unavailable, some of the
necessary information was obtained during the building inspection. It
was also crucial that the locations of all plumbing and electrical lines
were identified from the plans and/or inspection before drilling into
the slab for PFE measurements.
The most important parameter in assessing the applicability of ASD
is subslab communication or PFE. Clean, coarse aggregate, approximately
3/4 to 1-1/4 in. in diameter, is preferable for good PFE. PFE was
typically evaluated by using a shop-type vacuum cleaner for suction at
one larger hole (normally located at the potential ASD point) and a
tnicromanometer at other smaller holes. The suction hole was at least 1
in. in diameter, and the test holes were approximately 3/8 in. in
diameter and located at various distances and in various directions from
the suction hole, depending on building size and configuration. This
approach helped to indicate the feasibility of developing a pressure
field under various parts of the slab and also helped to identify the
influence of subslab barriers such as thickened slab footings or below
grade foundation walls. It is also helpful in indicating competing
pressures or excessive leakage from subslab ductwork which would inhibit
pressure field development in an ASD system.
Pressures at the primary (1-in. plus) suction point were typically
measured at suctions of about 8, 6, 4, 2 and 0 in. WC. If communication
testing indicated a pressure of - 0.001 in. WC or lower at a given test
hole, it was likely that an ASD system would be able to reach the area.
Final ASD system design depended on the results of the PFE
measurements and on other important factors including building codes
(with regards to penetrating firewalls, etc.), convenience, and
aesthetics.
8
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3.6 MEASUREMENT OF SUBSLAB RADON LEVELS
The radon concentrations under the slab were measured with a Pylon
AB5 monitor operating in a "sniff" mode. In this mode, subslab gas
samples are extracted through the 3/8 in. diameter test holes drilled in
the slab (these holes were then used in the PFE tests).
The Pylon was operated in a continuous mode with the internal pump
pulling approximately 2.5 L/min through a 300 ml scintillator cell. The
counting time for the Pylon was 30 seconds. After obtaining several
background counts, the sampling hose with an in-line membrane filter
(1 Mm) was inserted into the subslab hole. The number of counts
obtained in each counting interval was observed and the tube was removed
from the hole after two or three successive counts were obtained that
were within about 10-20 percent of each other. The length of time that
the sampling hose was in the hole was typically around 5 minutes. The
radon concentration was then calculated by subtracting the average
background from the in-hole count, converting the counts to counts per
minute, and then dividing by the cell efficiency (which was usually 1.2
counts/min/pCi/L. When the background count of the cell increased to
about 2 00 counts/min or more, the cell was replaced with a fresh cell
and the "hot" cell was flushed with outdoor air and allowed to recover
before it was used.
9
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SECTION 4
ALABAMA SCHOOLS
This section discusses two school buildings (Sections 4.1 and 4.2)
and one dormitory building (Section 4.3) in Alabama. The diagnostics
for all three buildings were conducted by Southern Research Institute
(SRI) , and the recommended mitigation plans were provided to the schools
for subsequent installation. Brief backgrounds on the two Decatur
schools and the Huntsville dormitory follow.
In January 1989, the Decatur school system made radon screening
measurements in each of the Decatur city schools since high radon levels
had been measured in many houses in the area. The screening
measurements were carried out in January 1989 and included measurements
in 2 to 3 rooms in each of the 18 buildings in the school system. These
tests identified five schools that had at least one room above 4 pCi/L.
Another school building (not used as classrooms), the Instructional
Service Center (ISC), measured 108 pCi/L during these screening tests.
In June 1989, follow-up measurements were made in about one-third of the
rooms in each of the five schools identified during the screening tests
as having a potential radon problem. The screening and June 1989
follow-up tests were carried out by a private testing firm,
Environmental Nucleonics, Inc. (ENI) of nearby Huntsville, using
charcoal liquid scintillation devices (CLSD). These measurements
identified two schools as having the most severe radon problems.
On September 1, 1989, a meeting was held with the Decatur school
system officials, ENI, and EPA/AEERL and its contractor, SRI. Following
this meeting, the design drawings of the two schools were reviewed,
followed by a short walk-through visit of both schools. It was agreed
that SRI would conduct diagnostic tests at the two schools, design a
mitigation system based on the results of the tests, provide guidance to
the school personnel in installing the system, and carry out
post-mitigation diagnostic testing.
The two Decatur schools included in this report are referred to as
Schools A and B. Both schools are located in the northwest corner of
Morgan County. The city is bounded on the north and northeast by the
Tennessee River and lies completely in the river valley. The elevation
of the region varies from 550 to 600 ft above sea level. Approximately
5 miles to the Northeast and 5 miles to the west are hills which have
outcroppings of limestone and shale. However, there does not appear to
be any near-surface bedrock within the city limits or any decomposed
bedrock in the clay soil. Past excavations have shown that the soil is
composed of dense red clay to a depth of 20 to 3 0 ft. The clay is deep
red in color, and contains very fine grains which should make it very
dense and impermeable.
The results of the diagnostic tests and the recommended mitigation
plan will be discussed separately in Sections 4.1 and 4.2 for Schools
A and B, respectively.
10
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As part of the Alabama State Radon Survey, radon measurements were
also made in several of the buildings at a Huntsville university in the
fall of 1989. The placement and retrieval of the charcoal canisters
(CCs) was done by a graduate student in biology under the direction of
a professor. As a result of these tests, one dormitory (referred to in
this report as school c) was identified as having extremely high levels
of radon in the basement of the building. The professor contacted the
Alabama State Office of Radiological Health for assistance and advice
regarding their problem who then contacted the U.S. EPA/AEERL, for
additional guidance and assistance. It was agreed that SRI would carry
niit* 1 aftnrse4" i r^c i n 4*K i c H n y* -m i ^ Vyii i 1 1 nrf oK i 1 o "in 4- Vi o 9r*oa 1 wfT
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diagnostics in the Decatur schools. The diagnostic tests in School C
were carried out on November 3, 1989, and the results are described in
Section 4.3.
4.1 SCHOOL A
4.1.1 Building Description
School A was originally built in 1949 with 14 classrooms, an
auditorium, cafeteria, offices, and rest rooms. Four classrooms were
added in 1957, two were added in 1961, and the final addition in 1963
included six classrooms in one area and extention of the cafeteria and
teachers' lounge. The total area of this single story, slab-on-grade
building is approximately 46,000 sq ft, with a total of 26 classrooms.
The plan of the original building and the additions is shown in Figure
4.1.1.
4.1.2 Pre-Mitigation Radon Measurements
The pre-mitigation radon measurements are summarized in Table
4.1.1. The results of the June 1989 follow-up radon measurements
carried out by ENI are also shown in Figure 4.1.2. In this series of
measurements seven rooms were identified as having radon levels above
4.0 pCi/L. The highest radon levels measured were 10.3 pCi/L in two
classrooms. Additional follow-up measurements were carried out by
school maintenance personnel over the period October 27-30, 1989, using
CCs provided and analyzed by the EPA. The locations of the canisters
are shown in Figure 4.1.3 for room identification. The results of the
measurements made in October 1989 are shown in Table 4.1.1 and Figure
4.1.4. A total of 33 rooms were tested. The average radon level in
these measurements was 5.0 pCi/L with a high reading 11.7 pCi/L in the
two offices and a low value of 1.1 pCi/L in the boiler room.
4.1.3 Building Investigation
The layout of School A is shown in Figure 4.1.1. Shown in Figure
4.1.5 are the locations of the thickened slab footings as specified in
the original design drawings. The footings are generally located along
the exterior walls of the rooms and along the interior walls parallel to
the hallways. No specifications were found on the drawings indicating
continuous gravel under these thickened slab footings; however,
11
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undefined gravel was called for under the slabs. This was most likely
river-run gravel containing particle sizes from fine sand to stone 1 to
2 in. xn diameter (a common practice at the time of construction)• It
was not clear from the architectural drawings if, when the additions
were constructed, the subslab areas of the additions were made
continuous with the existing subslab areas. If the subslab areas were
not connected, subslab communication between additions would be
unlikely,
The design drawings showed a utility tunnel as indicated in Figure
4.1.1. The tunnel exits to the outdoors on the west side of the
auditorium and runs under the auditorium and kitchen to the boiler room.
Another branch of the tunnel runs south under the auditorium and exits
into the sick room/coach's storage room across from the office. The
existence of pipes containing asbestos in the utility tunnel was not
determined.
Soil samples were taken at two locations near the building on
September 8, 1989. The locations of the sample sites are shown in
Figure 4.1.6. These locations were chosen to be near two classrooms
that tested high in the June 89 follow-up measurements. The soil
samples were taken by mechanically boring a hole in the soil to a
specified depth. At both locations (WD4 and WD5) samples were obtained
at depths of 1, 2, and 2.75 ft below the surface. These samples, along
with similar samples from School B, were sent for analysis to the EPA
Environmental Monitoring systems Laboratory in Las Vegas, Nevada. The
results of analysis for Ra-226 and Ra-228 content were not significantly
elevated above background levels. The average level was approximately
1.5 pCi/g with no clear trends with regards to sample depth.
4.1.4 HVAC System and Pressure Differentials
The classrooms are heated with fan coil units and cooled with room
air-conditioning units. No controlled outdoor air intakes were evident
in many of the rooms. No room or building pressure differential
measurements were made to determine building depressurization. Exhaust
fans were located m the kxtchen and ca f et e ri a areas, xn the rest rooms
and in the gymnasium. It did not appear that any provisions were made
for makeup air for the exhaust fans other than an occasional open window
or through leaks in the building shell.
4.1.5 Diagnostic Measurements
on November 3, 1989, a team from SRI carried out diagnostics in
School A. For the subslab communication tests and subslab radon profile
mapping, a total of 5 suction points (1-1/4 in. in diameter) and 35 test
points (3/8 in. in diameter) were drilled through the slab. The
locations of the suction and test points are shown in Figure 4.1.7. The
locations of these points were chosen more by space availability than
any other criteria. This distribution covered nearly every room of the
school except the auditorium, kitchen, and the boiler room.
12
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Prior to measuring the communication under the slab, the subslab
radon levels were measured using a Pylon AB5 operating in the sniff
mode. The levels measured at each slab penetration (with the exception
of four points) are shown in Table 4.1.1 and Figure 4.1.8. The average
of the 25 values was 568 pCi/L with a high of 1495 pCi/L and a low of 0
pCi/L. The October 89 room radon levels are plotted as functions of the
subslab levels measured in November 1989 in Figure 4.1.9. In a linear
regression between the two sets of data, some low correlation was found.
The linear regression line shown in Figure 4.1.9 has a correlation
coefficient of only 0.43 (an R2 value of 0.189) indicating a fairly low
correlation. However, this is typical of the correlation seen between
these two variables in previous research.
The results of the subslab communication tests are shown in Figures
4,1.10, 4.1.11, 4.1.12, 4.1.13, and 4.1.14. Each of these figures
depicts the communication measured from a separate suction point.
Suction Point 1. Located in Room 14 (Figure 4.1.10) about center
of the original north-south wing of the building. Communication
3C2TOS S thickened slab footing into the hall was excellent; however,
it was poor to Room 17 south of Room 14 and even worse to the
center of Room 14.
Suction Point 2. Located in a storage room (Figure 4.1.11) at the
south end of the same wing. Communication was excellent to the
adjacent janitor's room and fair into the hallway outside.
However, the pressures measured at test points in surrounding
classrooms could be reduced only from a positive to a less positive
pressure. These could not be pulled negative even with -6 in. WC
of suction at the suction point.
Suction Point 3. Located in Room 27 (Figure 4.1.12) which is part
of the 19 61 addition. Communication from this point to the hallway
was not as good as for suction points 1 and 2. However, the
pressure field measured in the center of Room 27 was excellent. No
pressure could be measured in Room 25 west of the suction point
location or across the hall and west into Room 24. Some
communication was measured in Room 26 but only enough to lower the
positive pressures to less positive values.
Suction Point 4. Located in an undesignated equipment room in the
1963 addition (Figure 4.1.13). Communication from this suction
point was better than for suction points 1, 2, and 3 but still was
limited to one to two rooms from the suction point.
Suction Point 5. Located in the coach's office in the original
part of the building (Figure 4.1.14). Communication was seen in
the principal's office located across the hall, and perhaps, into
Room 12 to some degree and also in the work room east of the
suction point. No PFE could be measured into the cafeteria. It is
possible that some of the negative pressure was being lost by short
13
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circuiting from the nearby utility tunnel.
In summary, the communication in this school is not good and is due
in part to the thickened slab footings and to the lack of clean, coarse
aggregate under the slabs. The "river run" gravel used has sufficient
particle size distribution including sand to restrict air movement. The
pressure field about each of the suction points is approximated by
circles in Figure 4.1.15. The maximum distance measured was about 35
ft, and the average distance was approximately 25 ft.
4.1.6 Mitigation Strategy
Active Subslab Depressurization (ASD) system designs are limited by
the poor subslab communication found in this school. It would appear
that, based on the data above, a suction pipe would need to be installed
in every room that measured above the 4 pCi/L guideline with provisions
made to extend to other rooms if necessary.
The recommended mitigation system is shown in Figure 4.1.16. A
total of 17 suction points are indicated. Suction points are suggested
in the following rooms (CC numbers -Figure 4.1.3); 01, 04, 05, 07(two
suction points) , 09, 11, 14, 17, 18, 20, 22, 23, 26, 27, 31, and 33.
Figure 4.1.16 indicates that provisions should be made during system
installation for additional suction points if necessary by installing
6 x 4 in. tees with the 4 in. outlet capped.
In the ASD systems shown in Figure 4.1.16, three in-line fans each
capable of moving approximately 400 cfm at 1 in. WC are recommended to
depressurize the regions under the slabs. For each system, the central
feeder pipe located in the hallway (above the tile in the dropped
ceiling if possible) should be a 6 in. diameter PVC, Schedule 40, pipe.
The connections to the suction points in the individual rooms should be
constructed of 4 in. diameter PVC, Schedule 40, pipe. The suction pipes
are connected to the main feeder pipe through 6x4 in. tees.
Additional tees should be installed in the 6 in. line in the event that
additional suction points need to be added. The 6 and 4 in. lines
should be sloped so that the water that condenses in the lines will
drain to the suction pits under the slab.
4.1.7 ASD System Details
The suction pits under the slab at each penetration should be
excavated to a minimum size of 36 in. diameter and 12 in. deep to
improve the performance of the ASD system. When the suction pipes are
installed through the cored holes in the slab, a coupling joint should
be used as shown in Figure 4.1.17. Care should be taken during the
installation to ensure that the suction pipe does not drop below the
bottom of the slab and reduce the air flow. The mains should exit the
V\i i i 1 i n f-f a 4- V» 21 titw v i Tfi a 4" a 1 4" "i nn es> eV) if1 q ^ g% n ts aV* f111 1 nl Wrs tn mi n 4" I
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at or near roof level in a vertical or near vertical orientation (no
more than 45° off the vertical). The fan exhaust should be directed
back over the roof and at least 30 to 50 ft away from any roof-mounted
14
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air intakes, windows, or doors.
All local and state building codes should be carefully followed.
These include: electrical wiring specifications for the fans (such as
using a separate circuit breaker and weatherproof conduits outside the
building) , and the use of materials that cut off fire where the PVC
pipes penetrate designated fire walls.
Some small gains in system efficiency could be achieved by sealing
the wall/slab cracks in the school. This should be done with urethane
caulking.
The success of the mitigation system should be assessed by using CC
measurements (with 10 percent duplicates) in each of the rooms, with
particular attention paid to rooms that have measured high in radon in
the past.
4.1.8 Estimated Cost
It is difficult to estimate the exact cost of the mitigation system
described above. The materials will probably cost in the range of
$5,000 to $8,000. Installation costs will depend on whether the school
maintenance staff does the installation.
4.1.9 Summary
In summary, it was demonstrated that the presence of high radium-
bearing rock outcroppings or soil loadings is not an essential precursor
for an indoor radon problem to develop. The radium levels in soils and
the building certainly do not indicate a possible problem. This school
has also demonstrated that the existence of aggregate under the slab as
indicated on the building plans is no assurance that good subslab
communications exist. Particle size and distribution and uniformity of
depth all play an important role in PFE.
There are no plans for additional diagnostics to be carried out in
this building unless the post-mitigation CC measurements indicate
elevated radon levels.
4.2 SCHOOL B
4.2.1 Building Description
This school was originally constructed as a single story,
slab-on-grade, high school in 1954. In 1961 an additional slab-on-grade
wing was added on the east side of the building. The layout of the
building and addition is shown in Figure 4.2.1. There are approximately
30 classrooms, several offices, a cafeteria, an auditorium, and a
gymnasium. The total area of the building is approximately 63,000 sq
ft.
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4.2.2 Pre-Mitigation Radon Measurements
The pre-raitigation measurements are summarized in Table 4.2.1. The
results of the June 1989 follow-up radon measurements carried out by ENI
are shown in Figure 4.2.2. In this series of measurements 11 of 14
rooms tested were identified as having radon levels above 4.0 pCi/L.
The highest level measured was 18.7 pCi/L in the front office.
Additional follow-up measurements were carried out by school maintenance
personnel over the period October 27-30, 1989, using CCs provided and
analyzed by the EPA. The locations of the canisters are shown in Figure
4.2.3. The results of the measurements taken in October 1989 are shown
in Figure 4.2.4. A total of 40 rooms were measured. The school average
radon level was 3.6 pCi/L with a high reading 11.1 pCi/L in Room 001 (CC
number 01) and a low value of 0.9 pCi/L measured in Room 008 (CC number
08). A total of 15 rooms had levels greater than 4 pCi/L.
4.2.3 Building Investigation
The layout of the school is shown in Figure 4.2.1. The original
building and addition are slab—on—grade, and have an abandoned hot water
radiant heating system in the slab floors as shown in the inset of
Figure 4.2.1. Because of deteriorating pipes, the floor heating system
was abandoned when the building was remodeled and converted to a grade
school. The intra-floor heating pipes are visible and accessible in the
boiler room where they have simply been cut off and plugged. The
building is now heated with fan coil units in the ceiling of each room.
Cooling is provided by individual air-conditioning units in each room.
An examination of the design drawings showed that the areas on each
side of the hall are on a continuous slab with no subslab footings or
walls between rooms. It was difficult to tell from the plans whether
the hall walls extended through the slab to footings or if any were set
on thickened slab footings. The drawings show that the building has
undefined aggregate under the slab. As in School A, this aggregate is
most likely river-run gravel from the Tennessee River nearby. This
gravel contains a full range of particle size from sand and silt to well
rounded stone 1 to 2 in. in diameter.
Soil samples were taken at three locations near the building on
September 8, 1989. The locations of the sample sites are shown in
Figure 4.2.5. Two of these locations were chosen to be near two
classrooms that tested high in the June 89 follow-up measurements. The
third location, LS3, was chosen simply as an interior point to the
building geometry. At each location, soil samples were taken at depths
of 1 ft, 2 ft, and 2 ft 8 or 9 in. The soil samples were taken by
mechanically boring a hole in the soil to the specified depth. As with
the samples from School A, the results of analysis for Ra-2 2 6 and Ra-228
content were not significantly elevated above background levels. The
average level was approximately 1.5 pCi/g with no clear trends with
regards to sample depth.
16
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4.2.4 HVAC System and Pressure Differentials
The school building is heated with fan coil units located in the
ceiling in each room. These units do not have outdoor air intakes. The
rooms are cooled by individual room air-conditioning units mounted in
the windows of most rooms. No fresh air is supplied to either the
heating or cooling system. Consequently, no pressure differential
measurements were made in any of the rooms. The only exhaust fans
observed were in the gymnasium, the kitchen, and the restrooms. No
provisions for makeup air to these fans were noted.
4.2.5 Diagnostic Measurements
On November 2, 1989, a team from SRI carried out diagnostics in the
school. For the subslab communication tests and the subslab radon
profile mapping, a total of 5 suction points (1-1/4 in. in diameter) and
32 test points (3/8 in. in diameter) were drilled through the slab. The
locations of the suction and test points are shown in Figure 4.2.6.
This distribution covered nearly every room of the school except Room
017, the gymnasium, kitchen, boiler room, and three of the offices.
Prior to measuring the communication under the slab, the subslab
radon levels were measured using a Pylon AB5 operating in the sniff
mode. The levels measured at each slab penetration (except for two
points) are shown in Figure 4.2.7 and summarized in Table 4.2.1. The
average of the 35 values was 620 pCi/L with a high of 1788 pCi/L and a
low of 128 pCi/L. The October 1989 room radon levels are plotted as
functions of the subslab levels measured in November 1989 in Figure
4.2.8. In a linear regression between the two sets of data, some low
correlation was found. The linear regression line shown in Figure 4.2.8
has a correlation coefficient of only 0.27 (an R2 value of 0.075)
indicating a fairly low correlation. This is a lower correlation
between subslab and room radon levels than that found at School A.
The results of the subslab communication tests are summarized in
Figures 4.2.9, 4.2.10, 4.2.11, 4.2.12, and 4.2.13. Each of these
figures depicts the communication measured from a separate suction
point.
Suction Point 1. Located in the center closet of Room 024 at the
far southwest corner of the school. As shown in Figure 4.2.9, with
an applied suction pressure of -2 to -4 in. WC, the pressure field
could be measured at a distance of 30 to 50 ft from the suction
point. With this much extension, depressurization could be
expected to cover all of Room 024 and a portion of Room 023.
Suction Point 2. Located in Room 020 across the hall from the
auditorium. As seen in Figure 4.2.10, the pressure field could be
extended for a distance of approximately 75 ft. Negative pressures
could be easily measured in the janitor's room at the end of the
hall, and marginally into the front office. No depressurization
17
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could be measured in either the auditorium or the cafeteria. The
cafeteria is well over 100 ft away and the auditorium slab is at
least 3 ft below that of the rest of the school. It is possible
that the depressurization was being short circuited by the large
number of floor/wall cracks in the auditorium, although this could
not be demonstrated using a smoke source.
Suction Point 3. Located in the teachers' lounge/workroom (CC
number 20) . With -4 in. WC of suction, the pressure could be
measured as far as 7 5 ft from the suction point as shown in Figure
4.2.11. With a suction point at this location, subslab
depressurization could be expected for Rooms 013, 014, 015, and
perhaps into Office 1.
Suction Point 4. Located in Room 025, a triangular room. The
pressure field extension about this point extended as far as 65 ft
at a suction pressure of -2 in. WC. This included Rooms 007, 009,
and 010 on the same side of the hall, and Room 008, the teachers'
work room, and the library across the hall as shown in Figure
4.2.12.
Suction Point 5. Located in the closet of Room 006. This room is
on the edge of the 1961 addition and subslab conditions appear to
be worse than those under the original building. As seen in Figure
4.2.13. with a suction pressure of -2 in. WC the pressure field
could be measured only inside the room and in the hallway directly
opposite the suction point. Additional suction pressures up to -4
in. WC did not improve the extension of the pressure field. It is
possible that the depressurization field was being short circuited
by being so close to the slab joint. A conservative estimate of
the pressure field in this end of the building is probably around
4 0 to 50 ft.
In summary, pressure fields from a given suction point may extend
as far as 40 to 50 ft in the newer part of the school and perhaps from
50 to 75 ft in the original building. This coverage is indicated in
Figure 4.2.14 by the circles drawn at each suction point. In drilling
the 1-1/4 in. diameter holes, it was evident that there was stone under
the slab. This appeared to be well rounded river stone about 1/2 to 1
in. in diameter with ample amounts of sand and fine silty clay.
4.2.6 Mitigation strategy
In designing this mitigation system, consideration was given to the
almost linear arrangement of the majority of the rooms and the
discontinuity of the remainder. In order to accommodate this geometry,
four fans are used to provide the necessary subslab depressurization.
Suction points are recommended in Rooms (CC numbers) 01, 02, 05, 14, 40,
19, 20, 22, 25, 26, and 39, as shown in Figure 4.2.15.
The northeast and northern wings lend themselves to a type of ASD
system that has been successful in other schools (e.g., at School I,
18
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Section 7.2). Rooms 01 and 02 each use fans capable of moving
approximately 400 cfm at 1 in. WC. The overhead pipes are carried down
the hall using 6 in. diameter schedule 40 PVC. It is possible that
these pipes can be located above the tile in the dropped ceiling. If
this is not the case, they will have to be installed in the hall in the
corner of the wall/ceiling junction. As was the case for School A,
above, the suction points should be constructed of 4 in. diameter
schedule 40 PVC. The suction pipes are connected to the overhead pipe
through 6 x 4 in. tees. Additional tees should be installed in the 6
in. line in the event that additional suction points need to be added.
The 6 and 4 in. lines should be sloped so that the water that condenses
in the lines will drain to the suction pits under the slab.
Fans 3 and 4 can be smaller than those used above since they will
be depressurizing a smaller area. A minimum suggested capacity is one
capable of moving about 200 cfm at 1 in. WC. A 6 in. diameter overhead
pipe and 4 in. diameter suction points are recommended.
The ASD system details discussed in Section 4.1.7 should be
followed.
4.2.7 Estimated Cost
It is difficult to estimate the cost of the mitigation system
described above. Materials will probably be about $5,000 to $10,000,
plus installation costs.
4.2.8 Summary
This school has provided another example of construction techniques
that will have to be addressed in order to mitigate public buildings
that were not designed with a possible radon problem in mind.
There are no plans for additional diagnostics to be carried out in
this building unless the post-mitigation measurements indicate elevated
radon levels.
4.3 SCHOOL C
4.3.1 Building Description
School C is a university dormitory building. The university is
located in the northeast corner of Huntsville. Huntsville is situated
in Madison County which is located in a known radon prone area. A state
survey of 144 homes in this county in 1986-87 found that 4 0 percent of
the houses tested were above 4 pCi/L. The average level of these
residential measurements was 5.6 pCi/L and the highest level found was
54.3 pCi/L. The university, in fact the city of Huntsville, is located
on the southern end of a radium bearing layer of Mississippian-Devonian
black shale (known as Chattanooga shale).
This three-story building has approximately 11,563 sq ft on each
19
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level. The lower floor is approximately 8 to 10 ft below grade along
the north side of the building and at grade along the south side. There
are 20 dormitory rooms (Rooms G1 through G20) on this lower level along
with a graduate teachers' lounge (G21) and a storage/janitor's room.
There is a common bath between each two-room suite. The area along the
northeast end of the building contains a crawl space with approximately
2,200 sq ft of exposed soil. The soil in this crawl space is not
covered and is separated from the remainder of the lower levels by
walls. The general layout and room number designations of this level
are shown in Figure 4.3.1.
4.3.2 Pre-Mitigation Radon Measurements
Initial CC measurements were made in October 1989 by a biology
student. The CCs were furnished by the Alabama Division of Radiation
Control (they were excess CCs from the Alabama State Survey). Twenty of
the 22 rooms on the basement level were tested over the above period,
and 13 had radon levels above 4 pCi/L. Two rooms measured
exceptionally high relative to the rest of the rooms tested. Two
additional sets of CC measurements were made with CCs provided by
EPA/AEERL in order to confirm the initial measurements. These two sets
of data are presented in Figure 4.3.1. These two sets of measurements,
made during March 28-30 and April 10-12, 1990, were highly variable.
The March CC measurements ranged from 0.7 to 480.2 pCi/L with an average
of 41.6 pCi/L. The April CC measurements ranged from <0.5 to 189.3
pCi/L with an average of 26.8 pCi/L.
4.3.3 Building Investigation
Diagnostic measurements were carried out by SRI in November 1989.
These measurements included sniffer measurements for radon entry,
measurements of the subslab radon levels, and subslab communication
tests.
\
The building design plans were provided by university personnel.
These plans indicated that the foundation construction included pier
footings and thickened slab footings with crushed stone under the slab.
The slab was covered with vinyl tiles in most areas. For visible areas,
the slab did not appear to have major cracks. Minor cracks (less than
0.1 in.) were found at some of the slab/wall joints. Utility lines for
water and waste are located below the slab in the hallway.
Access to the crawl space at the northeast end of the building was
from outside the building. Vents in the exterior wall of the crawl
space allowed some outdoor air to move rather restrictedly through the
crawl space.
4.3.4 BVAC System and Pressure Differentials
Heating and cooling for the building are provided by hot and cold
water supplied to individual fan coil units mounted in the ceiling of
each room. Fresh outdoor air is not provided to any of the rooms, other
20
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than through infiltration or open windows on the south side of the
building. The ceilings in each of the rooms and in the hallway are on
metal lath. The HVAC pipes are located above the plaster ceiling in the
hallway. Numerous rough openings into this area were evident as a
result of repairs to the HVAC system. No determination of the presence
or absence of asbestos in this area was made.
4.3.5 Diagnostic Measurements
One suction point (1-1/4 in. diameter) was drilled through the slab
in the storage room and test holes (3/8 in. diameter) were drilled in
the center of Rooms Gl, G9, G17, G17, and G21 as shown in Figure 4.3.3.
With a vacuum cleaner providing suction at Fa in the storage room of -1,
-2, and -4 in. WC, PFE was measured at the test points. The results are
shown in Figure 4.3.3.
Prior to carrying out the communication tests, sniffer measurements
were made of the subslab radon levels. The results of these
measurements are shown in Figure 4.3.4. The subslab radon levels ranged
from 239 to 1701 pCi/L with an average level of 1144 pCi/L.
During the communication tests visual examination indicated that
there was crushed stone under the slab. The extent and thickness of the
stone could not be determined through the relatively small holes drilled
through the slab. The extent of the pressure field produced with the
vacuum cleaner was fairly good. Assuming that the pressure field
decreases exponentially with distance from the suction point, an applied
suction of -2 in. WC should extend about 30 ft from the suction point as
shown in Figure 4.3.5. Using 30 ft as a maximum (a conservative value),
four suction points located as shown in Figure 4.3.6 should provide
complete coverage of the subslab regions.
4.3.6 Mitigation Strategy
Using the 3 0 ft estimate of coverage for a single suction point
operating at approximately -2 in. WC, the proposed suction points for
the mitigation system are shown in Figure 4.3.7. The suction points are
shown located in Rooms G2, G7, and G14, and the storage room. These
locations could be moved, if necessary, 4 or 5 ft and still achieve
adequate pressure field coverage. To supply suction to each of the
points, a 6 in. diameter overhead Schedule 40 PVC pipe should be located
in the hallway in the dropped ceiling. Installation of this pipe should
be possible without undue difficulty since there are numerous openings
already located in the plaster. These openings will supposedly be
closed when repairs to the HVAC system are completed. From the 6 in.
overhead pipe, 4 in. diameter, schedule 40 PVC suction pipes should be
used.
The 6 in. supply pipe located in the ceiling of the hallway should
exit the building on the east side and run up to roof level. The fan
should be mounted vertically above the roof line. The fan exhaust
should be directed back over the roof of the building to prevent
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reentrainment into open windows. The fan used should be capable of
moving approximately 4 00 cfm at a static pressure of about 1 in. WC and
be constructed for all weather conditions. The 6 in. line should be
sloped to ensure that the water that condenses in the pipe will drain to
soil level through the 4 in. suction pipes.
The ASD system details discussed in section 4.1.7 should be
followed as applicable.
4.3.7 Estimated Costs
Costs to install the mitigation system depend upon who does the
installation. If the university maintenance personnel carry out the
installation, the cost will be lowest. If a contractor is used the
costs are likely to run between $10,000 and $15,000.
4.3.8 Summary
In summary it was found that a dormitory building located in a
radon prone area can indeed have radon problems as great as or even
greater than those of single residential buildings in the same location.
The diagnostic tests suggest that, if the subslab regions are
uncomplicated and there is gravel or crushed stone under the slab, the
radon problem can be mitigated fairly simply.
There are no plans for additional diagnostics to be carried out in
this building unless the post-mitigation CC measurements indicate a
problem.
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SECTION 5
MARYLAND SCHOOLS
This Section covers three difficult-to-mitigate schools in
Maryland. These schools were identified as having elevated; levels of
radon in 1988, and have been studied by EPA/AEERL during 1989 and 1990.
One of the schools is located in Prince Georges County (School D,
Section 5.1), and the two others are located in Washington County
(Schools E and F, Sections 5.2 and 5.3, respectively).
When Prince Georges County schools were screened for radon in 1988,
School D had a number of rooms that were above 4 pCi/L, and county
personnel contacted EPA/AEERL for mitigation recommendations. A site
visit was made, and a number of interesting building characteristics
were noted that suggested that the school should be investigated more
closely. Since 1988, Infiltec has conducted radon diagnostic
measurements for EPA/AEERL in order to understand the radon problem in
this school. The research at School D is discussed in Section 5.1.
When Washington County screened their schools for radon in February
1988, School E showed all CC screening tests above 4 pCi/L. Elevated
levels of radon were also identified in School F. School E was selected
for research by the EPA because of its interesting slab-on-grade and
crawl space construction. School F was selected because the return-air
ducts for the HVAC system were located beneath the slab, presenting a
difficult-to-mitigate situation. Infiltec has studied the radon
problems in these two Washingtons County schools since 1988, and the
results are discussed in Sections 5.2 and 5.3, respectively.
5.1 SCHOOL D
5.1.1 Building Description
The original building (29,015 sq ft) was built in 1962 and is one
story with slab-on-grade construction. A 14,23 5 sq ft wing was added in
1966, and a library and additional wing were added in 1974 (11,393 sq
ft) . A utility tunnel runs parallel to the corridor in part of the
building, as indicated on the floor plan in Figure 5.1.1. The utility
tunnel is 4.5 ft high by 4.5 ft wide. It has a dirt floor and hollow
concrete block walls. The tunnel is 116 ft long, and the perpendicular
segment is 80 ft long. Test holes through the slab indicated that there
was no aggregate under the slab, and the soil is a sandy clay that is
not very porous to air flow.
5.1.2 Pre-Mitigation Radon Measurements
As seen in Figure 5.1.1, initial CC measurements in this school in
March 1988 averaged 4.2 pCi/L with the highest room measuring 12.3
pCi/L. A second set of charcoal measurements in November 1989 averaged
5.0 pCi/L, with two rooms measuring 10.0 pCi/1. Both sets of
measurements were made under closed school conditions when the building
23
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was not occupied, and the HVAC system was on normal weekend setback.
Continuous radon measurements in selected rooms in this school
raise a question whether there are significant elevated radon levels in
the school when the school is occupied (largely due to natural
ventilation). Figure 5.1.2 shows that the radon levels in Room 13 peak
on the nights and weekends when the school is closed. However, as soon
as the school is opened, the radon levels drop quickly, and it is
difficult to determine how much of the high initial radon levels seen
in the morning is due to the lags in the radon measuring device.
5.1.3 Building Investigation
The utility tunnel runs under or near eight of the classrooms in
this school as shown in Figure 5.1.1. Radon levels in classrooms in
this wing averaged 4.4 and 4.3 pCi/L for the two sets of measurements,
respectively. Large cracks between the floor and wall are visible in
some rooms. There is asbestos in the boiler room, but none is indicated
in the utility tunnel. The building plans and limited investigations do
not indicate any aggregate under the slab.
5.1.4 HVAC System and Pressure Differentials
The original HVAC system consists of a perimeter hot water system,
with air movement by convection. During the 1974 addition, ceiling-
mounted unit ventilators were added in each room to air-condition the
entire building. These overhead air-conditioning units — designed with
the capacity to provide outdoor air — have recently been modified to
provide heating so that they can be used year round. These units may
increase ventilation and/or pressurize the building to decrease radon
levels; however, operation of each unit is controlled in the classrooms
by the teacher and, consequently, continuous operation cannot currently
be ensured. There are also exhaust fans in the classrooms, as well as
m the 3^itcliei^ ancl j^esti^ooms« ScT^ool ^3ersonx^el stat^^d. 'ttiat^ ttie classrooxo
exhausts are rarely used. During nights, weekends, and holidays the
HVAC goes on a temperature setback.
5.1.5 Diagnostic Measurements
Inspection of the subslab material through test holes showed a
mixture of sand and clay under the slab. Communication tests showed
very low subslab air flow — no pressure was observed in test holes 5 ft
from the suction hole when the vacuum cleaner was at full power.
Experience in houses suggests that, if there is no aggregate under
the slab, poor subslab air flow (communication) is likely unless the
soil is very porous. Since the soil observed though test holes was a
sandy clay, with poor porosity, the poor communication test was not
unexpected. When this situation is found in houses, ASD can sometimes
be achieved by multiple suction points, more powerful fans, or baseboard
suction systems. In buildings with good communication, each suction
point may have a PFE of 20 ft or more, but with poor communication each
24
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suction point or baseboard system may have a PFE of only a few feet,
For these classrooms, the simplest system was a multipoint suction
system with one fan per classroom and a manifold to connect the fan to
suction points through the slab in three corners of the room, A
baseboard suction system would be more complicated because of built-in
cabinets on some of the walls.
5.1.6 Mitigation Strategy
Room 13, the classroom with the highest initial radon level (12.3
pCi/L in Figure 5.1.1) was selected to evaluate the applicability of ASD
in this school with poor subslab communication. (Previous efforts by
school personnel to seal the floor/wall cracks did not significantly
reduce the radon levels.) As seen in Figure 5.1.3, three 3 in. diameter
subslab slab penetrations were drilled in three corners of Room 13 and
manifolded to a 4 in. overhead line, with the pipe exiting through a
window near point A. In schools with good subslab communication, 4 to
6 in. diameter pipes are typically installed because of the high air
flow; however, because of the low air flow rates anticipated in the
mixture of subslab sand and clay, 3 in. diameter vertical pipes were
used in this school. To improve PFE, pits approximately 2 ft in
diameter and 1 ft in depth were excavated at the three suction
penetrations. A fan rated at 270 cfm at 0 in. WC was used for
depressurization.
5.1.7 Results of Initial Mitigation System
Radon levels measured in this school with the ASD system in
operation are shown in Figure 5.1.3. Note that a utility tunnel
depressurization system — that will be discussed later — was also in
operation in another part of the building during these measurements.
The radon levels in Room 13 and the adjacent room were reduced from
pre-mitigation radon levels of 7.1 and 7.4 pCi/L to 1.3 and 1.6 pCi/L,
respectively. It is apparent from Figure 5.1.3 that the November 1989
radon levels are lower through the building than the March 1989 levels
— not only in the areas where mitigation was being applied. However,
radon reductions in parts of the building where no mitigation was being
applied were about 45 percent (attributed to natural variations
resulting from weather, for example), and reductions in these two
classrooms were about 80 percent, indicating the influence of the ASD
system.
Subslab pressure measurements were made in test holes drilled
through the slabs in Rooms 13 and 14. In Room 13, negative pressures of
over 0.8 in. WC were measured within 1 ft of the suction holes and some
areas of the slab were negative by 0.1 in. WC or more. However, there
was a small region near the door (farthest from the three suction
points) that did not have any measurable negative pressure. In Room 14,
areas measured were at least -0.010 in. WC. This across-the-wall
subslab depressurization explains the low radon levels in Room 14 with
the ASD system. The performance of the multi-point ASD strategy in this
room suggests that, in low permeability situations, each room where
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suction points are installed might influence levels in adjacent rooms.
This would help to reduce the number of suction points needed if all the
classrooms had elevated radon levels,
5.1.8 Second Phase of Mitigation and Results
As mentioned in Section 5.1.4, the overhead air-conditioning units
in the classrooms — designed with the capacity to provide outdoor air
— were recently modified to provide heating so that they can be used
year around. These units may increase ventilation and/or pressurize the
building to decrease radon levels; however, operation of each unit is
controlled in the classrooms by the teacher and, consequently,
continuous operation cannot currently be ensured.
In order to determine if these units could potentially reduce radon
levels by pressurization and/or dilution, the system was operated
continuously during a weekend radon measurement. The building exhausts
were also operated during this measurement. As seen in Figure 5.1.4,
there does not seem to be any substantial reduction in radon levels.
5.1.9 Third Phase of Mitigation and Results
Depressurization of the utility tunnel was evaluated as a radon
mitigation approach since the tunnel has a large subslab area in contact
with the classrooms. An exhaust fan rated at 270 cfm (at 0 in. WC) was
installed in the tunnel at the end of the corridor. A 4 in. diameter
pipe penetrates the tunnel from the outdoors, and the fan is mounted on
a vertical riser at roof level. Differential pressure measurements were
made with the depressurization fan in operation at the two tunnel access
doors: one is located about 3 ft from the suction pipe penetration, and
the other is located near the tunnel by the two farthest classrooms.
The measurements showed depressurization of the tunnel to about 0.03 in.
WC at all points in the tunnel. A subslab pressure measurement was also
made in a classroom test hole about 10 ft from the tunnel, and
depressurization for the tunnel was negligible. (Remember that this
school is constructed on a mixture of sand and clay and, consequently,
has poor subslab communication.)
CC measurement results shown in Figure 5.1.3 indicate a reduction
in radon levels in the eight classroom area with the tunnel
depressurization fan in operation. The classroom levels averaged 1.8
pCi/L with the fan in operation compared to 4.4 and 4.3 pCi/1 (Figure
5.1.1), a reduction of about 60 percent. (It should again be noted that
the unmitigated areas average about a 45 percent reduction in these
measurements.)
Figure 5.1.5 shows continuous radon levels for 22 days in one of
the classrooms with the tunnel depressurization fan cycled on and off.
To include measurements during both occupied and unoccupied periods,
the fan was on from Wednesday noon to Saturday noon, and off from
Saturday noon to Wednesday noon. Radon levels in the classrooms
26
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averaged 1.2 pCi/L for the 8 days that the fan was on and 5.1 pCi/L for
the 14 days the fan was off. The overall average for the 22 days was
3.6 pCi/L.
Continuous radon measurements collected in the tunnel showed that
radon levels are similar when the fan is on and when the fan is off.
This implies that the radon levels in the classrooms are being reduced
because of the reversed pressure differentials between the tunnel and
the rooms, rather than diluting of the radon in the utility tunnel.
5.1.10 Final Radon Levels
The most recent post-mitigation radon levels are in Figure 5.1.3,
and the Room 13 ASD system and the tunnel depressurization are now
operating continuously. No further work by the EPA is planned in this
school.
5.1.11 Estimated Cost
The cost of radon mitigation in this school can be estimated by
comparion with house mitigation. Both mitigation systems that were
installed in this school are driven by 270 cfm fans that can produce a
pressure of up to 2 in. WC. This is the most typical radon mitigation
fan. If these systems were installed in houses nearby, the cost would
be approximately $800 per system, for a total of $1600. The parts cost
is $250 for the fan, pipe, and associated hardware. Approximately 16
work hours would be required to install each system. If the entire
school was to be mitigated, an ASD system would have to be installed in
about half the classrooms (about 14) at a cost of about $11,200.
The diagnostics time is difficult to estimate since the extensive
measurements that were done in this school were part of a research
project. The minimum diagnostic measurements would consist of subslab
communication tests, investigation of the HVAC system with pressure
measurements, and continuous radon measurements to determine diurnal
variations. These diagnostics would take about 16 work hours and are
estimated to cost about $12 00.
5.1.12 Summary
In spite of the poor subslab communication, it was reassuring to
learn that the radon levels could be reduced by installing enough
suction points in the ASD system. However, questions that still remain
include: 1) Would this approach work in a similar school with much
higher radon levels? 2) What mechanisms control radon reduction in the
adjacent classroom? and 3) With every room in the school with poor
subslab communication having elevated levels of radon, would one suction
point (or more) in each classroom (or every other classroom) be a
practical mitigation approach or should alternatives be sought?
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5 . 2 SCHOOL E
5.2.1 Building Description
Half of this single-story school is constructed over a crawl space
with two slab on grade Additions• The crawl space part of the building
was built in 1936, with wooden floor joists and a dirt floor in the
crawl space. The crawl space is 12,220 sq ft and has numerous support
piers. The slab-on-grade area is 10,350 sq ft.
5.2.2 Pre-Mitigation Radon Measurements
All eight charcoal screening measurements made by school personnel
in February 1988 were above 4 pCi/L. There is a large difference
between day and night radon levels in this school as shown by the
continuous radon plot in Figure 5.2.1. Although the radon level rises
steeply each night, it falls just as steeply as soon as school begins.
5.2.3 Building Investigation
The building plans show that the original school was built in 193 5
over a crawl space, and is about 12,220 sq ft. In 1967, a 10,350 sq ft
slab-on-grade addition was built onto two sides of the building. The
crawl space has a dirt floor and the wooden floor joists rest on a maze
of masonry walls. The foundation plan and specifications for the slab-
on-grade call for 4 in. of aggregate under the slabs. The addition was
constructed so that its floor would be at the same level as the crawl
space floor. Retaining walls were built and shale fill was used to
raise the level. The crawl space is accessible through hatches in the
floor, but the maze of support walls do not offer good access for laying
down a ground cover that could be sealed and depressurized, as is often
done for radon mitigation in houses. Some plumbing pipes are in the
crawl space, and all exterior vents appear to have been sealed for
security and to prevent the pipes from freezing.
5*y A. inri f Cife4*om D'»"aecm,,a Hi "Fciy*oT\t" isle
i c • *c n V AV Dy3 L-tSlll u 11*JI xr X. co o v.« X. fcS L> 111 cl 11- 1 CL _L o
The HVAC system is a single fan system with overhead ductwork. All
Washington County schools have HVAC systems that are controlled and
monitored by a remote computer system. All systems go into nightly and
weekend setback modes. Pressure differentials to the outdoors and to
the crawl space are very small and difficult to measure. Pressure
differentials across the crawl space floor were less than 0.001 in. WC
and were not measurably changed by turning on building fans or crawl
space depressurization fans. Since the floor above the crawl space was
not built to be airtight, very large air flows would be required to
create a significant pressure drop. The marked decreases in radon levels
during occupied hours is likely due to both pressurization and dilution
rather than the creation of a pressure barrier across the floor.
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5.2.5 Diagnostic Measurements
Since there is little experience with radon mitigation of large
crawl spaces, there are no guidelines for diagnostic analysis. Blower
door tests of the crawl space were attempted by sealing the blower
door fan into the crawl space entry hatch. The estimated leakage area
was about 10 sq ft. Across this opening a 500 cfm fan would generate
a pressure of about 0.0005 in. WC which would be just beyond the
measurement capability of the standard digital micromanometer. Radon
grab samples before the fan installation showed about 30 pCi/L in the
crawl space.
5.2.6 Mitigation Strategy
Mitigation techniques applied to crawl space houses include:
submembrane depressurization (SMD) in the crawl space, depressurization
or pressurization of the crawl space, and natural ventilation of the
crawl space. To date, research of crawl space houses has shown SMD to
be the most successful technique of the four for reducing radon levels
in the occupied area. However, since this school is much larger than
typical crawl space houses, the practicality of installing a SMD system
in this school crawl space may be very limited. In addition to the
largeness of the crawl space, it has many structural support walls and
piers throughout, which could quickly increase the cost of installing a
SMD system.
As a result, pressure control of the crawl space was investigated
in this school. A fan (Kanalflakt* rated at 510 cfm at 0 in. WC) was
mounted on one of the wooden panels that covered one of the crawl space
vents to exhaust air from the crawl space. To increase the fan's
effectiveness, the crawl space was sealed before evaluation of system
performance. Several large leaks between the crawl space and the boiler
room were sealed.
5.2.7 Results of Initial Mitigation System
Figure 5.2.2 shows continuous radon levels in the school office and
in the crawl space for a 16-day period cycling the crawl space
depressurization fan on and off for 4-day periods. Operation of the
depressurization fan tends to smooth out the peaks in the indoor radon
levels, although spikes above 4 pCi/L do occur. Spikes exceeding 10
pCi/L occur during periods when the fan is not operating.
School vacation began at day 357 and continued until around day
369. Radon levels in the office dropped considerably around day 369
when school was back in session even though the crawl space
depressurization fan was off and radon levels in the crawl space were
still quite high. The lower radon levels for days 369 to 373 seem to
indicate that normal HVAC operation creates a positive pressure, but
that during setback periods (nights, weekends, and holidays), the
building is under negative pressure, increasing radon entry.
*RB Kanalflakt, Inc., Sarasota, FL
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5.2.8 Second Phase of Mitigation and Results
The crawl space fan seems to be lowering the radon levels by simple
dilution, but it does not seem to be creating much of a pressure barrier
that would prevent soil gas from moving into the building. To increase
the depressurization, the crawl space must be sealed more carefully, or
larger exhaust fans should be installed.
To reduce radon levels in the slab-on-grade sections of the school,
three ASD systems have been installed by school personnel. These
systems were mounted externally by drilling a 6 in. diameter hole in the
retaining wall, just below the slab level. A Kanalflakt T3B in-line fan
was mounted on a 6 in. pipe that exhausts above roof level.
5.2.9 Final Radon Levels
Measurements by school personnel indicate that all classrooms are
now below 4 pCi/L, due to the combined action of the three ASD systems
in the slab-on-grade areas and the crawl space depressurization system.
5.2.10 Estimated Cost
Each of the four radon mitigation fan systems in this building were
installed by school maintenance personnel at a cost of about $670 per
system (or $2680 for the entire school). Three were ASD systems for the
slab-on-grade area of the building, and one was a crawl space
depressurization system.
The estimated cost for each of the four fan systems is:
1) $2 50 each for four fans
2) $100 for pipe and fittings for each system
3) 16 hours of labor for installation of each system at $2 0/hour
($320)
This school was investigated as part of a research project so many
more measurements were taken than would be included in a standard radon
mitigation diagnostic visit. The minimum diagnostics for this school
would probably consist of subslab communication tests in the slab-on-
grade section, a search for major leaks in the crawl space section,
pressure measurements to determine the HVAC system influence, and
continuous radon measurements to determine the diurnal variations in
radon levels. The minimum diagnostic analysis for this school would
have been approximately 16 hours at $75 per hour, about $1200,
5.2.11 Summary
Research in this school demonstrated that crawl space
depressurization has some potential for reducing radon levels in schools
constructed over crawl spaces. However, because of the wooden floor
joist construction (compared to a poured concrete floor) over the crawl
space, it was relatively leaky. Future research should look at the
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applicability of SMD, crawl space depressurization, crawl space
pressurization, and natural ventilation of the crawl space in more
detail to determine their performances in large crawl spaces typical of
schools.
5.3 SCHOOL F
5.3.1 Building Description
This school is single story with a slab-on-grade foundation, as
shown in Figure 5.3.1. It was selected for study because radon was
entering the subslab return air ductwork and being distributed to the
rooms by the HVAC system. In houses, this type of ducting has often
caused the houses to be difficult to mitigate.
5.3.2 Pre-Mitigation Radon Measurements
In 1988, 39 CC measurements made by school personnel indicated that
28 rooms were above 4 pCi/L, 8 rooms were above 8 pCi/L, and none were
above 20 pCi/L. (Note that these are not the data presented in Figure
5.3.1.) Figure 5.3.1 shows subsequent radon test results for each pod
classroom. The upper number is the initial radon test and the lower
number is the radon test results after mitigation. The original 1988
test results showed that Pod C, had the highest pre-mitigation radon
levels, while later tests showed that it had the lowest. Most of the
initial mitigation work was done on Pod C, and it was sometimes
difficult to determine if there was any mitigation effect because of the
lower levels.
5.3.3 Building Investigation
The building plans show that the original school was built in 1954,
and four "pods," each containing four classrooms, were added in 1964.
Both the original building and the additions are slab-on-grade
construction. The pod additions have an HVAC system with return air
ducts that are underneath the slab. The foundation plans and
specifications call for 4 in. of aggregate under the slabs. There are
no obvious cracks or other openings to the soil. Test holes confirmed
the presence of aggregate under the slab.
5.3.4 HVAC System and Pressure Differentials
The central pillar in the middle of each pod contains cold air
return ducts that go up to the overhead HVAC system. Subslab return
ducts run from the bottom of the pillar and out to the outside wall of
each room where the return air inlets are built into the walls below the
windows. With the HVAC system on, the pressure in the central pillar
return air duct was measured as -0.7 in. WC and the pressures in test
holes drilled through the slab ranged from -0.08 in. WC near the central
pillar to less than -0.001 in. WC at the edges of the rooms. Pressures
from the classroom to the outdoors and to the halls were not measured.
Any openings in the subslab ductwork would allow radon entry, especially
31
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when the ductwork was under negative pressure with the HVAC system
operating.
5.3.5 Diagnostic Measurements
Radon grab samples showed about 20 pCi/L in the HVAC supply air
when the system was turned on, which indicated that the return air
ducts under the slab were drawing in soil gas and recirculating it
through the school. Subslab radon measurements through test holes
drilled through the slab showed about 400 pCi/L. Communication tests
showed good PFE with the HVAC system off. However, when installed,
the ASD system was overwhelmed when the HVAC fan was turned on,
indicating a leaky subslab return air system.
5.3.6 Mitigation Strategy
Since pressure measurements indicated a pressure field that
ranged from about -0.1 to -0.001 in. WC of subslab pressure, it was
initially thought that an ASD system could reverse the subslab
pressure over most of the slab and produce significant mitigation. In
Pod c a 500 cfm fan (Kanalflakt GV9) was mounted on the roof, and it
was connected by a 6 in. manifold pipe to two 4 in. diameter pipes.
Suction points for these smaller pipes were drilled through the slab
near the return exhaust stack to maximize the suction where the
diagnostics had indicated that the return air subslab suction was the
highest. These slab penetrations uncovered good aggregate without
excessive fine material that would reduce air flow.
5.3.7 Results of Initial Mitigation System
The initial ASD system was not able to overcome the negative
pressures in the return air ducts. The diagnostic measurements of the
return air pressure field had been made through holes drilled through
the slab, and not relative to the return air duct under the slab. The
diagnostics had confused the small subslab negative pressure that was
caused by duct leakage with the much larger negative pressure in the
pipe. It is very unlikely that an ASD system could depressurize all
areas of the slab to levels approaching the 0.7 in. WC that would be
required to prevent soil gas from entering any cracks the duct.
However the ASD work was not in vain since the subslab ductwork would
have to be depressurized after it was sealed off.
Schools with subslab return air ductwork can create a radon
problem that may require abandoning the ductwork. Houses with supply
ducts under the slab have been mitigated with ASD, but it is doubtful
that houses with subslab return ducts will respond to this technique.
It is expected that schools will follow a similar pattern.
5.3.8 Second and Third Phases of Mitigation and Final Radon
Levels
In the second phase of mitigation, the subslab return ducts were
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abandoned and overhead return duct work was installed. However, no
reductions in radon levels were observed since the subslab duct work was
still open to the classrooms. However, the ASD system was effective
with the overhead return air ducts. Figure 5.3.2 summarizes the five
radon tests that were performed in this school. Tests 1 and 2 were
performed before mitigation started and showed levels from 5 to 13 pCi/L
throughout the pods. Test 3 was conducted after ductwork was sealed off
in pods A and C, and it is not clear if there is any reduction. The
third phase of mitigation consisted of installing ASD systems to
depressurize the sealed off subslab ductwork. In test 4, ASD was
installed in pod C, and significant reduction is shown, although the
levels in all pods are low. In test 5, ASD was added to pod A, as well
as pod C, and all pods are well below 4 pCi/L. It appears there was
significant spillover in radon from adjacent pods because pods B and D
have lower radon levels even though sealing or subslab depressurization
were not installed.
5.3.9 Estimated Cost
The estimated costs for relocation of the ductwork and mitigation
work can be broken down as follows:
a) $35,000 for replacement of subslab return ductwork by
overhead ducts;
b) $200 for foam and 8 hours of labor at ($20/hr) to seal
ductwork in each pod ($360 per pod for a total of $1440);
c) $350 for the fan and 8 work hours (at $20/hr) to depressurize
sealed subslab ductwork in each pod ($510 per pod for a total
of $2 04 0); and
d) the diagnostic work might be as much as 10 0 work hours at
about $75 per hour totalling $7500.
Because of the high cost of relocating the subslab ductwork, the
estimated cost of mitigating all four pods is roughly $46,000.
5.3.10 Summary
This school is an example of a rather expensive and time consuming
mitigation project. When a school or a house with a radon problem has
subslab return air ductwork, it is generally necessary to disconnect the
ductwork from the HVAC system, seal it off, and depressurize it. Until
the depressurization is accomplished, the mitigation effect of
disconnecting the ductwork and sealing it is often negligible.
33
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SECTION 6
NEW YORK SCHOOL/SCHOOL G
During early fall of 1989, Camroden Associates, Inc. (CAI)
contacted the New York State Energy Office (SEO) regarding schools in
New York State that had identified elevated radon levels. In turn, the
New York State Department of Health (DOH) was contacted in order to
identify several schools that had short-term radon measurements above 4
pCi/L.
During the week of September 27, 1989, representatives from the
EPA/AEERL, CAI, and SEO made site visits to a number of schools in
southwestern New York to explain the proposed project to school
officials and to perform preliminary building investigations. After the
initial investigations were completed, it was determined that School G,
located in Cattaraugus County, would most appropriately fit project
objectives.
6.1 BUILDING DESCRIPTION
School G consists of approximately 4 8,000 sq ft of gross floor
space of which 39,000 sq ft is single story slab-on-grade, 8,000 sq ft
below-grade basement, and 1,000 sq ft crawl space. All foundations
including the crawl space are constructed of poured concrete walls with
concrete floor slabs. The basement area contains some hollow-core
concrete block interior walls to define office spaces. The original
school building was constructed in 1965 with an addition constructed in
1986.
6.2 PRE-MITIGATION RADON MEASUREMENTS
A series of short-term measurements utilizing granulated activated
charcoal samplers were performed. Results indicated that the basement
area contained the highest radon concentrations, therefore it was
decided to direct mitigation efforts toward this area first. Unless
stated otherwise, all discussions that follow refer only to diagnostics
and mitigation conducted in the basement portion of the building. Figure
6.1 presents the results of the CC measurements made in the basement
area between October 7 and 9, 1989, with the school unoccupied. Radon
concentrations ranged from a minimum of 7.2 pCi/L to a maximum of 57.1
pCi/L. Frequency distribution of the 14 basement measurements at
intervals of 4 pCi/L (e.g., 0-4, 4-8, 8-12 pCi/L) revealed that <21
percent of the rooms had radon concentrations that fell between 40 and
44 pCi/L. The average of all basement concentrations was found to be
39.3 pCi/L with a standard deviation of 16.6. Tables 6.1 and 6.2
present an analysis of the October measurements in all regularly
occupied rooms in the school.
A second set of CC measurements were made from December 8 through
December 10, 1989, as presented in Figure 6.2. The school was occupied
during these measurements, and radon concentrations ranged from a
34
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minimum of 6.2 pCi/L in the boiler room to a maximum of 46.5 pCi/L in
the fallout shelter. Frequency distribution at 4 pCi/L intervals
indicates that 40 percent of the measurements fall in the 28 to 32
pCi/L range. Concentrations averaged 30.0 pCi/L with a standard
deviation of 11.0. Tables 6.3 and 6.4 present an analysis of these
measurements.
A final set of pre-mitigation cc measurements were made from
December 11 through December 13, 1989, with the school unoccupied. As
seen in Figure 6.3 radon concentrations during this period ranged from
a minimum of 27.3 pCi/L to a maximum of 58.8 pCi/L. Frequency
distribution at 4 pCi/L intervals indicates that 43 percent of the
measurements fall in the 32 to 36 pCi/L range. Concentrations averaged
35.3 pCi/L with a standard deviation of 10.6. When comparing the
results of all these measurements, note that the measurements made
during the last period did not include all of the basement rooms
included in the first two measurement periods. Analyses of measurements
during this period are presented in Tables 6.5 and 6.6.
6.3 BUILDING INVESTIGATION
The first step in the building investigation was to review the blue
prints of the building to familiarize the diagnostic team with its
construction and mechanical details. Foundation drawings indicated that
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A layer of polyethylene sheeting was placed on top of the compacted
subslab aggregate prior to the pouring of the concrete floor slab. The
majority of the interior walls of the basement are non-load-bearing stud
walls resting on top of the floor slab; however, load-bearing hollow-
core block walls resting on thickened slab footings were also used in
some areas.
The investigators made a thorough visual inspection of the school
during the diagnostic visit. Potential radon entry points were tested
using a Pylon AB-5 equipped as a radon sniffer. Typically, floor drains
in the school contained filled water traps. Radon concentrations in
these drains did not exceed the concentrations measured in the ambient
air. Radon concentrations in wall penetrations did not greatly exceed
the indoor ambient levels. Investigation of the small number of
floor/wall joint cracks revealed radon concentrations in excess of 300
pCi/L in the cracks.
The school had recently been surveyed for the presence of asbestos.
The main area of concern is minor amounts of pipe insulation in the
crawlspace area and floor tiles in the original portion of the school.
All asbestos-containing materials have been clearly marked or recorded.
Special consideration for these areas must be given during the
mitigation work.
6.4 HVAC SYSTEM AND PRESSURE DIFFERENTIALS
The HVAC system in the school consists of unit ventilators. Hot
35
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water for each room unit ventilator is supplied by a central boiler
located in the basement. Outdoor air dampers in each unit ventilator
are controlled by temperature sensors and time clocks. There is no
central cooling system in the school. The unit ventilators used for
heating in the slab-on-grade portion of the school are typically located
on the outside wall of the classroom; however, some units are located
overhead in the dropped ceiling with outdoor air intakes located on the
roof.
Combustion makeup air for the 2.1 MMBtu boiler is supplied through
a passive air intake located in the ceiling of the boiler room. Measured
air intake while the boiler was running at low speed was 2400 cfm. With
the boiler operating at high speed, the air intake volume did not change
noticeably. It is therefore suspected that the air intake is supplying
all of the air possible, and additional air intake capacity may be
warranted.
Inspection of the unit ventilators revealed that the outdoor air
intake louvers were not open; therefore, little or no outdoor air was
being introduced into the rooms. The New York State Education
Department requires rooms to be supplied with at least 10 cfm of fresh
air per student when the outdoor temperature is 35° F or higher.
Investigation of the controls revealed that the pneumatic lines had been
disconnected at the control board and at most unit ventilators. When
questioned about this, school officials indicated that the unit
ventilators were disconnected during the heating season to save energy.
6.5 DIAGNOSTIC MEASUREMENTS
Using a Pylon AB-5 portable radon monitor equipped to operate as a
radon sniffer, potential radon entry points were investigated. As
previously stated, floor drains and wall penetrations did not seem to be
the major radon entry points. Although the floor/wall joint cracks were
introducing relatively high radon concentrations into the basement area,
the small leakage area and low volume of airflow through the cracks
combined to convince the investigators that the floor/wall cracks were
only a minor source of the indoor radon. Subslab radon concentrations in
the basement area were found to range from 400 to 1450 pCi/L. The
approximate locations and concentrations are presented in Figure 6.4.
Subslab communication was measured using a Kanalflakt XL-4 in-line
centrifugal fan for the source of depressurization. Basement-to-subslab
pressure differentials were measured using a digital micromanometer.
Locations of the suction point and remote tests holes are shown in
Figure 6.5. Pressure differences and approximate distances from the
suction point are listed in Table 6.7.
6.6 MITIGATION STRATEGY
Based on results of the diagnostic tests, a mitigation strategy
combining ASD and HVAC modifications was recommended.
36
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ASD in Basement Area
Based on the results of the subslab communication testing, a five-
point ASD system was recommended. All five points were manifolded to a
common exhaust constructed of 4-in. schedule 40 PVC piping. Down-legs
from the exhaust manifold were constructed of 3-in. schedule 40 PVC
piping. A valve to restrict system airflow was installed in each down-
leg. The exhaust manifold penetrates the roof at a point where there is
no chance for exhausted soil gases to re-enter the school through air
intakes. ASD is provided by an in-line centrifugal fan capable of
moving 400 cfm of air at 0 in. WC static pressure. A device to cut off
the spread of fire was placed in the exhaust piping at the point where
the piping penetrates the existing firewall. A system failure device
consisting of a pressure transducer and warning light was also
installed. Figure 6.6 illustrates the placement of penetration points
and piping routes.
HVAC Modifications
New York State Department of Education codes require that a minimum
of 10 cfm of outdoor air per occupant be delivered to each room when
outdoor air temperatures are 3 5°F or higher. To save energy, an often
used, but incorrect, procedure is to disconnect or obstruct outdoor air
intakes for the unit ventilators at the beginning of the heating season
and reconnect them at the end of the heating season. This procedure is
not recommended for any of the ventilators in the school, including
those in the slab-on-grade section and the unit serving the basement.
Often a disconnected or otherwise disabled outdoor air damper is left
inoperable. Also often during the heating and transitional seasons,
when the outdoor air is 3 5°F or higher, physically disabling the outdoor
air intakes will prevent fresh air from being introduced during these
periods. It is suggested that the unit ventilators be made to operate
per the design specifications of outdoor air temperature and time
schedule. This xs not within the cognizance of radon mitigators and
should be left to the school's maintenance staff or HVAC service
contractor.
A regular maintenance program should include all maintenance
procedures prescribed by the unit manufacturer. Care should be taken to
ensure that air intakes are not blocked by debris or other materials.
Avoid placing other contaminant-producing items (e.g., garbage cans or
automobile exhausts) near the outdoor air intakes.
The air intake supplying combustion makeup air to the boiler should
be further investigated by the school's architect/engineer and HVAC
contractor.
6.7 RESULTS OF INITIAL MITIGATION SYSTEM
Prior to installing the ASD system, a Pylon AB-5 continuous radon
monitor equipped with a passive radon detector was placed in Office 4 to
37
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gather pre-mitigation radon concentration data. During the pre-
mitigation monitoring period between December 14 and 28, 1989, radon
concentrations in the office averaged 34.2 pCi/L with a standard
deviation of 4.1. These data are presented in Figure 6.7. Analysis of
the data is presented in Tables 6.8 and 6.9.
During the week of January 22, 1990, the ASD system was installed.
A continuous radon monitor placed in Office 4 gathered data with the
system operating in the passive mode from January 26 to 31, 1990. Radon
concentrations during that period averaged 21.0 pCi/L with a standard
deviation of 4.1.
On the afternoon of January 31, 1989, the fan system was activated.
Radon concentrations over the next 2 4 days averaged 11.2 pCi/L with a
standard deviation of 2.6. Data from both modes of operation are
presented in Figure 6.8. Analysis of the data is presented in Tables
6.10 through 6.13.
Short-term measurements using activated CCs were made in the basement
area from February 12 to 14, 1990. Results of these measurements are
presented in Figure 6.9. Basement radon concentrations during that
period averaged 8.0 pCi/L with a standard deviation of 4.2. Analysis of
data is presented in Tables 6.14 and 6.15.
6.8 ADDITIONAL DIAGNOSTIC MEASUREMENTS
A series of experiments designed to provide mitigation system
operation and optimization data were performed in February 1990.
Initial procedures called for installing the ASD system with no suction
pits dug beneath each suction point. Measurements were made to assess
the strength and extent of the subslab pressure field with the control
valve fully open. Suction pits were then dug and the measurements
repeated. Results of the before and after measurements are presented in
Figure 6.10. Adjustments were made to the restricting valve placed in
each down-leg to distribute the pressure field beneath the floor slab to
cover as much subslab area as possible. Pressures in the pipes with all
valves open and no suction pits, with all values open and suction pits,
and with valves adjusted are presented in Figure 6.11.
Short-term activated charcoal measurements were made between March 13
and 15, 1990, after the suction pits had been dug and the system
pressures had been adjusted. Radon concentrations averaged 5.0 pCi/L
with a standard deviation of 2.0. These data are presented in Figure
6.12 and in Tables 6.16 and 6.17. Additionally, a continuous radon
monitor was placed in Office 4 immediately after adjustment of the
subslab depressurization system. Radon concentrations between March 2
and March 30, 1990, averaged 8.6 pCi/L with a standard deviation of 2.5.
Hourly radon concentrations during that period are presented in Figure
6.13.
During the summer of 1990, the dampers for the basement unit
ventilator were opened to provide outdoor air (both for pressurization
38
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and dilution) . As seen in the continuous radon data presented in
Figures 6.14 and 6.15, addition of the outdoor air through the unit
ventilator consistently reduced radon levels to below 4 pCi/L in the
basement office.
6.9 SUMMARY
Based upon the short-term and continuous radon measurements made at
the school, it appears that the ASD system combined with opening the
outdoor air dampers for the basement unit ventilator have dramatically
lowered the radon concentrations in the basement area.
Additional actions to further reduce radon concentrations in the
basement include providing a greater volume of combustion make-up air to
the boiler and sealing the crawl space from the basement area.
Provisions will also be made to provide outdoor air to the classrooms in
the slab-on-grade area on a year-round basis.
39
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SECTION 7
TENNESSEE SCHOOLS
EPA's Office of Radiation Programs in cooperation with state and local
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public school buildings throughout the U. S. The radon concentrations
in approximately 3,000 classrooms were measured using weekend CC
detectors during the winter of 1988-89. These measurements included 11
schools in Nashville, Tennessee. The Nashville schools had by far the
most elevated radon levels measured in the 13 0 school buildings
surveyed. As a result, the Nashville area schools were targeted for
radon mitigation research by EPA/AEERL during the summer of 1989.
Six of the 11 Nashville schools with the most severe radon problems -
as measured in the survey — were selected for diagnostic
measurements. Based on the results of the diagnostic measurements and
radon levels, Schools H and I were selected for mitigation system
installation, as discussed in Sections 7.1 and 7.2, respectively. The
screening levels in School H ranged from 1.5 to 13 6.2 pCi/L with an
average value for all rooms tested of 39.5 pCi/L. Follow-up
measurements in selected rooms a few weeks later ranged from 24.1 to
148.8 pCi/L with an average value of 69.2 pCi/L. The screening levels
measured in School I ranged from 8.9 to 52.5 pCi/L with an average for
all rooms tested of 29.7 pCi/L. The follow-up measurements in selected
rooms at School I ranged from 30.0 to 42.6 pCi/L with an average of 37.5
pCi/L.
Diagnostic measurements were also made in four other Nashville
schools. The recommended mitigation system designs for these schools,
referred to as Schools J, K, L, and M, are discussed in Sections 7.3,
7.4, 7.5, and 7.6, respectively. The recommended mitigation strategies
for these four schools were submitted to school officials for
implementation.
7.1 SCHOOL H
This school is located in northeast Nashville just southwest of the
Opryland USA theme park and adjacent to the Cumberland River. This
school is located in a high radon area that includes numerous
outcroppings of Mississippian - Devonian black shale known as the
Chattanooga Formation (4). This outcropping runs through the middle of
the state and is considered to be an area with high risk of elevated
radon levels.
7.1.1 Building Description
School H is two stories high in the north and south classroom wings,
and one story in the rest of the building. It has 19 first floor,
slab-on-grade classrooms, two classrooms located over a crawl space, and
two basement rooms with two classrooms located above. In addition
-------
to these classrooms there are two gymnasiums with boys' and girls'
locker rooms along with other rooms used to teach music and shop. The
school has a centrally located kitchen and cafeteria located between the
classroom wings. The slabs for the cafeteria and kitchen are recessed
below the classroom wings by approximately 4 ft. There are an
additional 23 classrooms and a library located on the second floor of
the building. The central and northern portions of the school were
constructed in 1960. An extension to the north wing of classrooms was
added in 1961 and in 1962 the south wing of classrooms was added. The
latest addition to the school was made in 1963 when the west wing was
extended with a locker room and additional gymnasium and music room.
The original building and additions are shown schematically in Figure
7.1.1. The location of classrooms and measurement numbers are as shown
in Figures 7.1.2 and 7.1.3, for the f irst and second floors,
respectively.
7.1.2 Pre-Mitigation Radon Measurements
The initial radon screening measurements were made during the weekend
of February 4, 1989. These tests used CCs provided by EPA, Montgomery,
Alabama, and were deployed and retrieved by personnel from the Nashville
Metro School Board and from the Tennessee Department of Health and
Environment, Division of Air Pollution Control. The results of the
initial screening measurements are shown in Table 7.1.1 and Figure
7.1.4. The highest level (136.2 pCi/L) was measured in Room 102. The
lowest level measured (1.5 pCi/L) was in Room 130 located directly over
the art room. The average for all rooms tested was 39.5 pCi/L. Follow-
up measurements carried out over the weekend of February 18, 1989 (also
shown in Table 7.1.1 and Figure 7.1.4), gave a value of 148.8 pCi/L in
Room 102, the highest found. The lowest value during the follow-up was
measured in the music room. The average of the four follow-up readings
was 69. 2 pCi/L.
The highest readings in both sets of measurements were found in Room
102. This classroom was previously a science room. When the room was
changed to a home economics classroom, the science laboratory stations
were removed. However, the openings in the slab where utility lines
entered were not closed off. These openings were sealed by the school's
maintenance staff in late February or early March 1989. Subsequent
measurements carried out in March 1989 (also shown in Table 7.1.1 and
Figure 7.1.5) in this room indicated a radon level of 33.3 pCi/L. This
lower value may be the result of sealing some of the major entry points.
It could also be due to the seasonal variation in the radon levels since
the average temperature during the February measurements was
approximately 30°F, whereas the temperatures in March were 40-50°F. A
more likely possibility is that the reduction is due to a combination of
both the sealing and the seasonal variability. However, the radon level
was still elevated, which indicated additional radon entry paths.
The measurements in March 1989 resulted in an average of all rooms
tested (11 rooms) of 27.9 pCi/L with a high of 41.7 pCi/L measured in
41
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Room 104 (adjacent to Room 102) and a low of 17. 0 pCi/L measured in the
music room. The average reading was lower than before and reflects that
the openings in Room 102 were sealed and also that the weather was
warmer than before. The average air temperature in February 1989 was
39•0°,F whereas in March the average had increased to 52.6°F.
Pre-mitigation measurements made over the weekend from June 2 to 6,
1989, are shown in Table 7,1.1 and Figures 7.1.6 and 7.1.7, for the
first and second floors, respectively. For these pre-mitigation tests
CCs were used in most rooms, and electret detectors (E-Perms) were
collocated in some rooms. The average of the CC readings in all the
rooms tested was 8.9 pCi/L with a minimum reading of 1.9 pCi/L in the
wood shop and a maximum of 35,2 pCi/L in the girls' dressing room
adjacent to the large gym. The E-Perms gave similar results for
locations that coincided with the CC measurements (see Figures 7.1.6 and
7.1.7). The average of the rooms tested with the E-Perms was 7.3 pCi/L
with the lowest value of 0 pCi/L measured in Room 120 and the highest
value of 35.2 pCi/L measured in Room 102.
The data from the February and June pre-mitigation CC measurements are
plotted in Figure 7.1.8 along with the best fit regression line. The
regression analysis indicates that the June CC values were only about 14
percent of the values obtained in February. The regression line in
Figure 7.1,8 is:
Rn(June) Value (pCi/L) = 3.7 + 0.14 x Rn(Feb) Value .
Some of the differences in the values can be attributed to seasonal
effects and to the fact that the June values were obtained after the
school maintenance personnel had sealed the floor cracks and openings in
the 10 classrooms with the highest levels measured during the screening
tests. Other factors may also have caused the levels in June to be so
much lower than those in February.
7.1.3 Building Investigation
The building is a two-story concrete and steel structure with brick
veneer on most of the exterior surfaces. The original building was
constructed in 1960 with additions in 1961, 1962, and 1963 as shown in
Figure 7.1.1. The construction under most of the first floor classrooms
is slab-on-grade with pier footings. The subslab material is river run
stone. Examination of the foundation and wall section plans indicated
that the two hall walls and the walls between classrooms in the
slab-on-grade areas are not load-bearing, and rest on thickened slab
footings. The plans also indicated the presence of aggregate extending
under these footings.
The 1961 four-classroom addition at the north end of the original
building resulted in what appeared to be a solid wall under the slab
between these added rooms and the original building. At the
southernmost end of the south wing (the 1963 addition), a four-classroom
42
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addition was built partly over a basement and partly over a crawl space.
On the basement level there is an art room and a room called the TV room
used primarily by the maintenance staff. These two rooms are
below-grade on three sides. On the north, these rooms are adjacent to
a crawl space. This crawl space is located under Room 128 and a portion
of Room 127 as shown on the floor plan, Figure 7.1.2.
The roof of the building is a flat poured-concrete slab covered with
tar and river stone. The roof slab extends from the edge of the
building with an overhang of about 3 ft. The presence of the slab roof
precluded routing any mitigation fan exhaust pipes directly through the
roof. Also, the Nashville School Board suggested that an alternate
route for the fans be found other than cutting holes in the roof slab.
This has been the case in a number of other schools that EPA has worked
with. The primary concern of the school is that any hole or opening cut
through the roof would invalidate any existing roof warranty.
Most of the floors of the building are covered with asphalt tile. The
concrete for the slabs was formed with cement and river stone. The
specified thickness of the floor slabs was 4 in. Numerous cracks were
found both at the installed expansion joints and where the various
additions to the school were attached to the existing structure.
7.1.4 HVAC System and Pressure Differentials
The building has hot water radiant heat along the outside walIs in all
areas except the basement. The heating systems for the art and TV rooms
are two separate HVAC units. These central air handling systems are
located in the adjacent crawl space. The air handler showed ample
evidence of crawl space air leakage. The portion of the building heated
with hot water has no active ventilation except infiltration. The
original windows in the building have been replaced with a combination
of solid panels and weather stripped windows, reducing the potential for
ventilation through infiltration.
A blower door test run on one segment of the building (the five rooms
numbered 102, 104, and 106 in Figure 7.1.2) indicated that these rooms
were fairly tight. The total floor area of these rooms was
approximately 2,507 sq ft and the volume was approximately 30,000 cu ft.
The effective leakage area was calculated to be about 156 sq in. and the
air change rate at 4 Pa pressure was measured to be 1.3 air changes per
hour. Probably half of the air infiltration was due to air leaks around
the windows in the hallway walls. The remainder was most likely due to
air leakage through the window-mounted air-conditioner units.
The building is air-conditioned by window units mounted in the solid
window panels in each classroom. All of the fresh air intakes on the
window units were closed to conserve energy. The effects of the HVAC on
any mitigation system installed in the art or TV room are not expected
to be significant.
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7.1,5 Diagnostic Measurements
On June 5 and 6, 1989, subslab communication tests and mapping of the
subslab radon levels were carried out at School H by personnel from SRI,
EPA, the Nashville Metro School Board, and the Nashville Metropolitan
Health Department.
The subslab radon profile is shown in Table 7.1.1 and Figure 7.1.9.
The values ranged from a low of 50 pCi/L under the entry hall to the TV
room, to a high of 5700 pCi/L under the north hall slab. The average
subslab level was 2066 pCi/L. An attempt was made to correlate the
subslab radon levels to the those measured in the rooms. The values are
plotted against one another in Figure 7.1.10. In this figure only
values from Table 7.1.1 are shown for which there were both subslab and
pre-mitigation CC measurements. The room radon levels measured in the
initial February 1989 screening, the February 1989 follow-up, in March
1909 after the cracks and openings in the 10 highest rooms were sealed,
and the June 1989 pre-mitigation measurements are all plotted as
functions of the subslab radon levels measured in June 1989. As seen in
Figure 7.1.10 the correlation between the subslab levels and the
February room levels appear to be much higher than between the subslab
levels and the March or June room levels. This could be because the
stack effect is greatly reduced in June over what it was in February and
March. Also, the subslab levels were, for the most part, measured in
the center of the room. However, the major entry points into a given
room may well be at the edges of the room through cracks xn the
slab/wall joint and through the slab expansion joints in several of the
classrooms. These entry points were sealed, at least partially, early
in March 1989. Consequently, even though subslab communication was
excellent in this school (except for the art/TV rooms), the room levels
may be dependent more on the subslab levels between rooms which were not
measured. This is an area in which little is known at present. Data
will be presented in the School I discussion (Section 7.2) where subslab
communication was much poorer than at School H.
For the subslab communication measurements an industrial vacuum
cleaner provided the suction to the subslab regions. The hose of the
vacuum cleaner was inserted through a 1-1/2 in. diameter hole drilled
through the slab in the closet of Room 104 (in the north wing), in the
mnsr office of Room 121 (m the south wing), and also through a hole in
the southwest corner of the art room. The speed of the vacuum cleaner
was varied to produce a vacuum in the hose of (generally) -2, -4, and -6
in. WC. The pressure difference between the subslab and the classroom
was then measured (as a minimum) at the center of each room using a
micromanometer sensitive to less than 0.001 in. WC. The micromanometer
readings were usually taken through the 3/8-in. diameter holes drilled
for the subslab radon profile measurements. During the measurements,
care was exercised to ensure that both the vacuum cleaner hose and the
micromanometer hose were well sealed to the slab with rope caulking.
44
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Results of these PFE measurements at School H are shown in Tables
7.1.2, 7.1.3, 7.1.4, and 7.1.5. The locations of the suction points and
the test holes are shown in Figure 7.1.11. The pressure field
extensions are summarized in Figures 7.1.12, 7.1.13, and 7.1.14, where
the subslab depressurization measurements are plotted as a function of
the distance from the suction points located in the closet of Room 104
(Figure 7.1.12), in the office of Room 121 (Figure 7.1.13), and in the
basement art room (Figure 7.1.14). Note that the actual measured
pressures have been normalized to the source pressure according to the
relation pi/po, where pi is the subslab pressure difference relative to
the room pressure and po is the subslab pressure at the suction hole
relative to the room pressure.
As shown in these figures, measurable PFE could reliably be measured
at distances of up to 100 ft from the suction point in Room 104 and up
to about 75 to 80 ft from the suction point in Room 121, although
subslab communication was considerably less in the art room. Here the
pressure under the slab could be measured in the center of the art room
(23 ft from the suction point) but could not be measured in the TV room.
It is possible that the aggregate under these slabs was either less in
quantity or the aggregate used was composed of much finer particles. It
is possible that the aggregate was filled with fine sand, clay, or silt.
The subslab material exposed when the 4-in. hole was bored through the
slab was somewhat different from that seen in the other holes in areas
that had much better PFE. The aggregate in the art room did in fact
appear to contain more clay fines and silt.
The pressure fields measured with -4 in. WC suction are summarized in
Figure 7.1,15. As seen in this figure, excellent subslab
depressurization was measured from Classrooms 101 to 106 in the north
wing. Depressurization under the rooms on the east side of this wing
appeared to be as good as under those on the west side of the hall.
This showed that suction under the thickened slab footings under the two
hall walls did not cause any significant loss of pressure and confirmed
that there was aggregate under the thickened slab footings as shown on
the building plans.
The negative pressures measured under the slabs of the four room
addition (Rooms 107 to 110) were surprising. It was not anticipated
that these rooms would communicate with the rest of the rooms in the
north wing because during their addition the original brick walls were
left in place. However, when the wall at the end of the initial hall
was broken out to extend the hall, the foundation was apparently broken
below the aggregate level, with the aggregate continuing down the hall.
Consequently, it was possible for the suction from Room 104 to reach
these other four rooms via the hallway aggregate. In the south wing the
pressure field extension was not nearly as great as in the north wing.
Although Room 126 (farthest from the suction point) did not show any
negative pressures under the slab with the vacuum cleaner test, it was
anticipated that, with installation of a larger suction fan and suction
point in Room 121, a pressure field could be generated. It has been
true in the past that the larger suction hole and fan of the permanent
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mitigation system can produce a greater pressure field extension than is
typically seen using the vacuum cleaner in a small hole drilled through
the slab. Also, when the mitigation system is installed, it is common
practice to excavate a suction pit under the slab which greatly improves
the PFE.
7.1.6 Mitigation Strategy
In view of the excellent subslab communication it was decided that
both the north and south wings could be mitigated with only one suction
point in each wing. The location of the suction point for the north
wing was in the closet of Room 104. The suction point for the south
wing was in the office of Room 121. It was also concluded that a
separate subslab depressurization system would have to be used for the
art and TV rooms. Initially it was thought that 8 in. diameter pipe
would have to be used in each of the classroom wings to handle the large
flow of air that would be withdrawn from under the slabs. As a result,
on June 7, 1989, two 9 in. diameter holes were cored in the slab; one
in the closet of Room 104 and one in the office of Room 121. Temporary
mitigation systems were installed at these two points on June 8 and 9,
1989. These temporary systems were constructed using 6 in. diameter
flexible PVC drain pipe attached to separate fans (Kanalflakt T4 Turbo,
rated at 410 cfm at 1 in. WC) mounted inside the building on a sheet of
plywood installed in the window opening. The exhaust of each fan was
outside the class room and directed away from the building at about S ft
above the ground.
It was decided that, if these systems proved successful in lowering
the radon levels in the north and south wings, they would later be
installed permanently using the same suction points with the fans
located outside the building just below the roof overhang. Since these
temporary systems were actually quite successful, permanent systems were
installed with the suction points and fans connected using 6 in.
diameter, Schedule 40, PVC pipe. The pipe from the suction point in the
closet of Room 104 was run across the room parallel to the corridor into
Room 106 and then out the exterior (west) wall perpendicular to the
corridor. On the exterior wall of the building the pipe turned
vertically up the side of the building to the fan located under the roof
overhang. The fan exhaust was routed over the roof edge to exhaust back
over the roof of the building.
Since the second suction point was in the office of Room 121 at the
front of the building, for aesthetics the pipe run was across the hall,
through Room 122, and out the rear of the building. From this point the
pipe ran vertically up the side of the building with the fan located
under the roof overhang. The exhaust of this fan was also above the
roof line and directed back over the building. No air intakes are
within 30 to 40 ft of the fan exhausts. By locating the exhausts above
the roof level, reentrainment into the building via open windows or
window air conditioners on the second floor should not be a problem.
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The art and TV rooms were mitigated with a system separate from those
in the other two wings of the building. A 4 in. diameter suction point
was cored in both of these rooms and connected by 4 in. diameter,
Schedule 40, PVC pipe to a single fan (Kanalflakt T3A Turbo, rated at
135 cfm at 1 in. WC) located under the roof overhang. The fan exhaust
was again directed over the roof of the building.
Visual alarms were installed for each fan. These included pressure
sensitive switches (Grainger* model 2E462 Multi Purpose Air Switch) with
red and green indicator lights. The operation of these alarms is such
that, if the fan is running and providing negative pressures, the green
light is on, and if the fan stops or the negative pressure is less than
about -0.1 in. WC, the green light goes out and the red light turns on.
If all power is lost to the mitigation fans, both lights go out. In
either a no-light or red-light status the school maintenance staff has
been instructed to call the Nashville Metro Operations Office.
Mitigation of other parts of the school, in particular the music room
and the two shop rooms on the west end of the building, was not planned
during this initial phase. Although the radon levels measured in the
February 1989 screening tests (shown in Figure 7.1.4) indicated elevated
levels in this area of the school, this was not replicated in
measurements made in March 1989 (shown in Figure 7.1.5) and June 1989
(shown in Figure 7.1.6). Consequently, the decision was made to
postpone any mitigation efforts unless elevated radon levels were later
detected.
7.1.7 Results of Initial Mitigation System
The temporary mitigation systems located in Rooms 104 and 121 were
activated about 7 pm on June 8, 1989. Previously a continuous radon
monitor (CRM) (Pylon AB5 radon monitor with PRD1 passive cell) was
located in Room 102. The monitor was again placed in Room 102 when the
ASD systems were activated. On June 12 the CRM was moved to Room 121,
and it was moved again to Room 124, and finally on June 20 the CRM was
placed in Room 127. The CRM followed the radon levels in these rooms
and recorded the levels every 60 minutes. The results are shown in
Figure 7.1.16. The pre-mitigation levels in Room 102 never reached a
maximum due to time limitations for the use of the detector. Also, the
levels were probably lower than the pre-mitigation CC levels measured
during the first part of June because of the installation activity
(e.g., open windows, doors). The average level in Room 102 was about
3.0 pCi/L, in Room 121 it was 1.3 pCi/L, in Room 124 it was 2.3 pCi/L,
and in Room 12 7 it was 1.6 pCi/L. These values were confirmed through
CC and E-Perm measurements between June 24 and June 26. The results of
these measurements are tabulated in Table 7.1.1 and summarized in
Figures 7.1.17 and 7.1.18. Here the average level measured in 37
locations was 2.7 pCi/L with a minimum of 0.9 pCi/L in Rooms 105 and 120
and maximum of 6.2 pCi/L measured in the art room, where the ASD system
was not yet installed. The art/TV room system was installed and
activated on July 28 at about 2 pm.
*W. W. Granger, Inc., Illinois
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The E-Perm measurements carried out at the same time as the CC
measurements are also shown in Table 7.1.1. For these post-mitigation
measurements the average of the rooms tested was 2.5 pCi/L with a
minimum value of 0.9 pCi/L measured in Room 120 and a maximum value of
9.9 pCi/L in Room 123. It is interesting that the highest and lowest
E-Perm values were measured in the rooms nearest the room with the ASD
suction point (interior office of Room 121). The highest value would
seem to be suspect.
The PFE made with the temporary mitigation systems installed in Rooms
104 and 121 were measured on June 28. The results are tabulated in
Tables 7.1.6, 7.1.7, 7.1.8, and 7.1.9 and summarized in Figure 7.1.19.
The results are also summarized in Figure 7.1.20 where the subslab
pressures (normalized to the suction hole pressure) are plotted as a
function of the distance from the suction hole. It is seen that a
measurable pressure field could be measured as far away from the suction
point as 100 ft or more. This again illustrates the excellent
communication under the slab. Velocity traverses were carried out in
the suction pipe approximately 1 ft above the slab. These measurements
indicate that the flow through the ASD system in Room 104 was
approximately 192 cfm at -1.91 in. WC and the flow through the system in
Room 120 was 255 cfm at -1.77 in. WC. The higher flow rate through the
system in Room 121 was later found to be due to rather large air leaks
in the slab expansion joint along the north wall of Room 121. These
were sealed on August 2, 1989,
The permanent mitigation systems in Rooms 104 and 121, and in the
art/TV rooms were operational on July 28. Pressure field extensions
achieved with these systems were measured on August 4. The results are
listed in Tables 7.1.10, 7.1.11, 7.1.12, and 7.1.13 and summarized in
Figure 7.1.21. The pressure measurements and the locations are shown in
Figure 7.1.22. From the results shown in Figure 7.1.21 it is evident
that measurable pressure fields extend farther than 100 ft from the
suction points in the main wings of the school. The suction point in
Room 104 was operating at a pressure of -1.91 in. WC at a flow rate of
180 cfm and the system in Room 121 at a pressure (after sealing the
leaking expansion joint along the north wall of Room 121) of -1.75 in.
WC at a flow rate of 236 cfm.
Two suction points were installed in the art/TV rooms; one in the
southwest corner of each room. The two suction points were connected to
a single fan (Kanalflakt T3B Turbo 8, 230 cfm at 1 in. WC) located under
the roof overhang. The pressure field in the art room was measured at
-0.04 in. WC in the center of the room (about 23 ft from the suction
point) with the suction point operating at a pressure of -1.03 in. WC
and a flow rate of about 13 5 cfm. The pressure field in the TV room was
measured to be -0.03 in. WC at a distance of about 25 ft from the
suction point operating at -0.85 in. WC and a flow rate of about 50 cfm.
Based on these measurements it was expected that the three sub-slab
depressurization systems should be sufficient in the two main wings of
the building. No additional suction points were anticipated for the
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main classroom wings of this school.
Post-mitigation CC measurements were carried out in July with the ASD
systems located in Rooms 104 and 121 operating. These results are
listed in Table 7.1.1 and summarized in Figure 7.1.23. The average
radon level for the rooms tested was 2.6 pCi/L with a minimum value of
0.5 measured in several rooms. A maximum value of 19.8 pCi/L was
measured in the art room, where the mitigation system for the basement
area was not operating until July 28.
The post-mitigation CC measurements with all three systems operating
were repeated in August and the results are listed in Table 7.1.1. The
measured values are also summarized in Figures 7.1.24 and 7.1.25. The
average radon level measured in the August tests was 0.8 pCi/L with a
low of 0.5 pCi/L (the lower limit of detection for the CC) and a high of
2.2 pCi/L measured in the music room. (Note that the music room was not
mitigated during these measurements and is not shown in the figures.)
The only areas not likely to be controlled by these three systems were
the gyms and associated locker rooms, the music room, and the shop
areas. Because of the variability of the summer results, these areas
were re-tested in December 1989 before pursuing mitigation in this area.
7.1.8 Additional Phases of Diagnostics and Mitigation
Beginning in late November 1989 and into December a water condensation
problem developed in the mitigation system installed in Room 104. In
this system, the 6 in. diameter PVC duct was routed across the adjoining
Room 106 to gain an access path out the west side of the building.
Because of the location of existing hot water heating pipes in Room 106
and in order to clear a concrete support beam in the exterior wall, the
installation of the 6 in. duct resulted in a low point or swag in the
duct located in this room. As a result of this swag, the condensation
that occurred in the duct up the outside of the building drained back
into the low section of duct in Room 106.
During the cooler months of November and December 1989 condensation
caused the duct to fill with water to the point that the air flow
through the duct was reduced. Also, during extremely cold days the
water actually froze in the 90 degree elbow just outside the building
and completely blocked the air flow to the fan. In an attempt to remedy
the problem the school maintenance personnel installed a drain cock at
the bottom of the elbow outside the building. This provided a means of
draining the accumulated condensate during warm periods but was
ineffective during prolonged cold periods. On December 14, 1989, a
sketch of an "S" type water trap and drain was given to the maintenance
staff to be installed at the lowest point in the duct in Room 106.
Because of problems caused by a severe freeze in the Nashville area and
the Christmas holidays, the water trap and drain were not installed
until late December.
CC measurements were repeated in the school between December 1 and 4,
1989. Prior to these measurements, approximately 60 gal. of condensate
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was drained from the mitigation system pipe in the north wing. However,
on December 4 when the CCs were retrieved, it was noted that the red
warning light was on in the mitigation system in Room 104. This
indicated a loss of suction pressure to the subslab region due to the
buildup of water in the pipe. It is not known when during the December
1-4 period the depressurization was lost. These results are listed in
Table 7.1.1 and summarized in Figure 7.1.26. In these tests, the
school's average radon level was 7.2 pCi/L with a low reading of 0.6
pCi/L in Room 130 (located over the basement art room) and a high
reading of 38.0 pCi/L in Room 107 (located in the north wing) . The
radon levels in the west wing of the building were well above the August
levels (shown in Figure 7,1.24) particularly in the music room and main
gym. These levels indicated the need for a mitigation system in the
west wing of the school and for additional corrective action on the
water problem within the system in Room 104.
The values measured during this period were about the same as the
August readings (shown in Figure 7.1.24) for the south wing and basement
areas of the school. The levels in the north wing and in the kitchen
and cafeteria were significantly above the August readings. These
elevated levels are almost certainly due to the condensation problems in
the pipe running through Room 106. The levels in the kitchen and
cafeteria reflect the loss of depressurization due to the problem with
the mitigation system in Room 104. Previous tests had shown that the
depressurization in these rooms was due entirely to the suction point in
Room 104.
On December 14, the ASD system was completely drained of condensate
(approximately 55 gal. of water) using the drain cock located outside
the building. Following this, the depressurization was measured in
several rooms in the north wing to determine whether the system could
recover after removing the collected condensate. The results indicated
that, if the condensation problem could be corrected, the system should
perform as well as it did the previous summer.
As a permanent solution to the condensate problem, a 1/2 in. plastic
pipe with an "S" type water trap was installed by the school maintenance
staff in late December, The drain from the trap was connected to the
waste drain in the restroom in Room 104. This trap was modified on
January 4 and filled with oil to prevent the trap from drying out with
a subsequent loss of suction pressure in the system.
Also, between January 2 and 5, Rooms 107 and 108 were examined to
determine why the levels were so high in the December 1989 CC tests. It
was not certain that the high readings were entirely due to the
condensate problems in the mitigation system for the north wing. These
rooms were high when the building was initially tested in February 1989
(Figure 7.1.4) and it was found at that time that these high levels
resulted from a 1 in. expansion joint along the south side of these two
rooms. This expansion joint resulted when the four-room addition was
added to the north wing in 1961. This expansion joint is under a 4 in.
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angle iron which is about 3/8 in. above the floor. As a first step in
the early mitigation efforts by the school personnel in March 1989 , this
crack was sealed with silicone caulking. Following this initial effort
the radon levels in Room 107 were reduced by about 50 percent (follow-up
levels in Figure 7.1.4). On reexamination in January 1990 these seals
were found to have shrunk in a number of places leaving some very large
openings between the subslab and the room. These cracks were carefully
resealed in January 1990.
Also in January 1990, a single point ASD mitigation system was
installed in the music room in the west wing of the school. The 5 in.
diameter suction point was cored through the slab in the band director's
office. Before the 4 in. diameter PVC pipe was installed, approximately
15 gal. of aggregate and soil was excavated from under the slab. The 4
in. PVC line exited the music room on the north side of the building and
turned vertically to a fan (Kanalflakt T3B Turbo 8, 230 cfm at 1 in. WC)
mounted at roof level. The outlet of the fan was directed over the roof
of the building away from any possible reentrainment sites. This
mitigation system was operational on January 9, 1990. Measurements of
the subslab depressurization produced by the fan indicated excellent
coverage in the music room itself, but no depressurization could be
measured in the shop adjacent to the music room. The pressure at the
suction point in the music room was -1.35 in. WC at a flow rate of
approximately 200 cfm.
Another problem that required correction in January was replacement
of the fan in the mitigation system in the art/TV rooms. On January 5
it was discovered that the fan was not running. It was replaced on
January 9 and the defective unit was returned to the supplier for
analysis, the results of which indicated failure of the starting
capacitor. The defective capacitor was replaced and the fan returned.
7.1.9 Final Radon Levels
Post-mitigation CC measurements in the north and west wings of the
school were repeated over the weekend of January 12—15, 1990. These
results are listed in Table 7.1.1 and summarized in Figure 7.1.27. The
average level in those rooms tested was 0.8 pCi/L with a minimum value
of 0.5 pCi/L measured in several rooms and a maximum value of 1.3 pCi/L
measured in Room 104 where the suction point is located. The results in
the north wing were essentially the same as was obtained in August 1989
(Figure 7.1.24). Consequently, the system, after modification, was as
effective as it was during the summer. The results obtained in the
cafeteria and the kitchen were 0.7 and 0.5 pCi/L, respectively. This
showed that the system was still mitigating this area as it did during
the previous summer.
7.1.10 Estimated Cost
The cost of materials and work hours expended in the diagnostic
evaluation, both pre- and post-mitigation, and for the actual
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installation of the mitigation systems are shown in Table 7.1.14.
7.1.11 Summary
The results in the north wing of School H are remarkable since one
suction point is creating negative subslab pressures under an area
totaling over 15,000 sq ft. The farthest point in Room 109 is about 120
ft from the suction point, the longest distance of any subslab PFE
measured thus far in the radon program. This results from the fact that
there is an adequate layer of clean, coarse, crushed aggregate under the
slab and no subslab barriers; i.e., the aggregate is continuous over the
entire wing and free of fines or silt. There was a subslab barrier
between the initial building and the four-room 1961 addition at the
north end of the building. However, when the north exterior door of the
original building was removed, the wall was apparently broken out below
slab level and the aggregate installed continuously down the hall into
the addition. This was initially shown by good subslab depressurization
under the hall in the new addition as was seen in Figure 7.1.15.
In summary, it was demonstrated that, if the subslab communication is
good and the pressure field can be extended far enough from a single
point, radon mitigation of large areas of the building can be
accomplished. However, to determine this fact requires more than a
cursory diagnostic examination of the building. Also, because most
existing schools are constructed in phases over periods of time and
because construction techniques vary not only from school to school but
from addition to addition, each element of the building must be examined
individually and the mitigation system designed specifically for that
portion of the physical plant.
7.2 SCHOOL I
This elementary school is located approximately 5 miles south-
southwest of School H and about 1 mile east of the Nashville
Metropolitan Airport in eastern Nashville. This location is also in the
high risk area for potential radon as identified in the Tennessee
survey. (4) Several of the houses included in the EPA Nashville Radon
Mitigation Demonstration for Detached Dwellings are located within 5
miles of the school.
7.2.1 Building Description
The original portion of the school was constructed in 1954 and
included 13 classrooms, an auditorium/cafeteria, a kitchen, and two
offices. The first addition in 1957 included four classrooms at the
south end of the original building. Both the original structure and the
1957 addition were slab-on-grade; however, the first addition slab is
approximately 4 ft lower than the original. The most recent addition was
completed in 1964 and included a four classroom crawl space structure on
the northwest side of the school. The 19 64 structure is connected to the
rest of the building by an enclosed hallway. The layout of the school
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is shown in Figure 7.2.1. The mitigation studies in this school were
carried out during the summer of 1989 and were limited to the
slab-on-grade portion of the building. The crawl space wing was
mitigated during the 1989-90 school session, and data are still being
analyzed.
7.2.2 Pre-Mitigation Radon Measurements
The initial radon screening measurements were made during the weekend
of February 4, 1989. These tests used charcoal canisters provided by
EPA, Montgomery, and were deployed and retrieved by personnel from both
the Nashville Metro School Board and from the Tennessee Department of
Health and Environment, Division of Air Pollution Control. The room
locations and the screening measurement numbers are shown in Figure
7.2.2. The results of the initial screening measurements are shown in
Table 7.2.1 and Figure 7.2.3. The highest radon level measured in the
initial screening was 52.5 pCi/L in Room 113 in the original building.
The lowest reading was 8.9 pCi/L in Room 116 which is located over the
crawl space. The average level of radon in all 2 2 locations tested was
29.7 pCi/L. The average temperature in the Nashville area over this
testing period was approximately 28°F.
Follow-up measurements in late February 1989 retested the four highest
rooms identified in the initial survey. These results are also shown in
Table 7.2.1 and Figure 7.2.3. The follow-up average was of course much
higher (37.5 pCi/L) than before since only the rooms with the highest
screening measurements were tested. The minimum value during the
follow-up testing was 30.0 pCi/L in Room 102 (part of the original
structure) and the maximum was 42.6 pCi/L in Room 120 (again part of the
original structure). From these tests it appeared that the
slab-on-grade portion of the school had the greatest radon problem;
however, the rooms over the crawl space are still elevated and need to
be addressed in the mitigation scheme. Also, the follow-up values
showed less of a decrease than the follow-up measurements in School H
(Section 7.1) during the same period, indicating that the seasonal
variation is school and site specific. The average temperature over the
follow-up measurement period was approximately 40°F, about 12°F higher
than during the initial measurements.
Pre-mitigation CC measurements were made the first week of June 1989.
These results are shown in Table 7.2.1 and Figure 7.2.4. For these
measurements the average of 22 locations was 21.7 pCi/L with a minimum
of 3.2 pCi/L in Room 116 (over the crawl space) and a high of 93.4 pCi/L
in Room 120 (located in the slab-on-grade original structure). The
average Nashville temperature during this period was 74°F. It was not
surprising that the June levels were on the average somewhat lower
(about 25 percent lower) . What was surprising was the fact that the
highest level had increased by almost a factor of 2. The climatic
conditions between February and June 1989 were quite different. The
average temperature during this measurement period was about 46°F higher
than the initial February measurements.
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Pre-mitigation CC measurements were repeated again in July 1989. The
results of these measurements are shown in Table 7.2.1 and Figure 7.2.5.
The school average radon level was 22.9 pCi/L which is very close to the
average obtained in June (21.7 pCi/L). The highest reading was 108.9
pCi/L in Room 120, as before. The lowest reading obtained was 4.4 pCi/L
in Room 113.
The building clearly had a significant radon problem with some rather
interesting seasonal variability of the levels. The levels in some of
the classrooms increased as the outdoor temperature increased and yet
the levels in other rooms decreased. The seasonal variability is best
seen in Figures 7.2.6 and 7.2.7 where all of the pre-mitigation CC
measurement results are summarized.
7.2.3 Building Investigation
Examination of the foundation and wall section plans indicated that
block walls on all four sides of all rooms and closets in the original
building extended to footings under the slab. There was no indication
of breaks in these subslab walls which reduced the potential for subslab
communication between rooms. The wall section drawings also indicated
the presence of 4 in. of aggregate of unspecified size under the slabs.
The foundation drawings of the 1957 addition, containing four
slab-on-grade rooms, indicated that not all the walls go through to
footings; there was a possibility of good subslab communication between
these four rooms. This was later confirmed by the communication tests
described below.
The 1964 four-classroom addition is constructed on a slab-above-grade
with a crawl space under the slab. The height of this slab above the
soil varies from approximately 6 ft at the north end to less than 3 ft
at the south end nearest the rest of the school. There is an entry door
to the crawl space at the north end of the building. Diagnostics and
mitigation in this section of the building were conducted at a later
date.
7.2.4 HVAC System and Pressure Differentials
There is no central HVAC system in the school. Each room is heated
by a fan coil unit mounted above the dropped ceiling. The heated air
from the fan coil is ducted to the ceiling registers near the outside
wall. Cold air return is through an unducted opening very close to the
air intake of the fan coil unit. Consequently, it is unlikely that the
fan coil units cause much negative pressure in the plenum above the
ceiling. The steam pipes are located in the hallways above the ceiling
tiles. There was ample room above the ceiling tiles in the hallways to
run PVC pipe for an ASD system.
The rooms are cooled in the warmer months by individual window-mounted
air-conditioners in each room. The fresh air intakes for these have all
been closed off. Five wind-driven turbine roof ventilators exhaust air
from the building. These are located in the hallways in the plenum
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above the suspended ceiling. Most of the classrooms in the original
structure also have small ventilator fans mounted in the hall wall and
exhausting into the hall. It is not certain how these fans are
operated, if at all. There are two large kitchen exhaust fans, an
exhaust hood over the cooking unit, and an exhaust fan for the
dishwasher.
7.2.5 Diagnostic Measurements
Diagnostic measurements were carried out between June 6 and 8. These
included mapping the radon levels under the slabs in each of the
classrooms, measurement of the subslab communication, and spot radon
measurements in selected locations. The subslab radon levels were
measured as described above for School H. The results are shown in
Table 7.2.1 and Figure 7.2.8. The average subslab radon level was 828
pCi/L with a high of 1900 pCi/L under the auditorium/cafeteria and a low
of 300 pCi/L under the hall slab near Room 120.
On comparing the subslab radon levels with the levels in the rooms
above, there appears to be little or no correlation, just as was the
case in School H. It is even more puzzling at School I than at School
H. The subslab communication measurements discussed below showed that
the ability of the subslab region to exchange soil gas from one region
to another was very poor compared to that at School H. The relationship
between subslab radon and room radon levels is an area that needs more
investigation to develop an understanding of the processes involved.
The results of the subslab communication tests are listed in Tables
7.2.2, 7.2.3, 7.2.4, and 7.2.5. Selected values of the pressure field
measurements are shown on the floor plan in Figure 7.2,9. The initial
suction hole was placed just inside Room 110, near the door. It was
possible to pull a negative pressure in Rooms 109 and 111, and in the
hall just outside Room 110. However, no communication could be detected
in Room 120, the room across the hall. Similar results were obtained at
the other end of the building. From these tests, it was concluded that
subslab communication could be extended about 30 ft in the original
building and could typically pull through one subslab wall, but not
through two walls. Even within the same room, pressure field extension
was much poorer than that found at School H. Consequently, it was felt
that the aggregate contained more fines than the aggregate at School H.
This was confirmed when aggregate samples from under the slab were
removed and compared during installation of mitigation systems at the
two schools. At School H, the stone was very large, from 3/4 to 1 in.
in diameter. At School I, it was much finer, averaging about 1/4 in. in
diameter and contained some fines and or silt. It was also noted that
aggregate depth was less than 1 in. in some locations. In both schools,
the aggregate appeared to be screened river gravel.
A suction point in Room 114 of the four-room slab-on-grade addition
indicated good subslab depressurization in Rooms 112, 113, and 115 as
might be expected based
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drawings.
The subslab PFE measurements in School I are summarized in Figure
7.2.10. Here, the pressures measured at each test hole in the slab have
been normalized to the source suction pressure. As seen in this figure
the pressure field produced with the vacuum cleaner could be extended to
only about 30 ft.
7.2.6 Mitigation Strategy
In view of the relatively poor subslab communication, it was decided
that the mitigation systems for this school should include, as a
minimum, one suction point in every other room, on both sides of the
hallway. Provisions should also be made so that additional suction
points could easily be installed in the remaining rooms later, if
necessary. The mitigation systems for the original building included
two in-line axial fans each providing depressurization for about half of
the slab-on-grade classrooms. The physical layout of the piping and fan
locations are shown in Figure 7.2.11.
Each system provides subslab depressurization to five or six rooms.
Each system was composed of a 6 in. Schedule 40 PVC supply (or trunk)
line running down each of the north-south hallways. This supply main
was located in the hall plenum above the suspended tiles. At each of
the respective class rooms a 6 to 4 in. tee was installed to provide a
4 in. tap for the actual sub-slab suction pipe. Both of the 6 in.
mains exited at the rear of the building above the hall doors.
Individual fans (Kanalflakt T4 Turbo, 410 cfm at 1 in. WC) were located
just below roof level and their exhaust was directed over the building
roof. Four-inch Schedule 40 PVC pipes were brought through the wall
into the classrooms and then down into 5 in. suction holes cored in the
slab. The rooms where suction points were installed are shown in Figure
7.2.11. Six suction points were installed in the east wing of the
original building and five in the west wing. No suction points were
installed in the office, the teachers' lounge, or the work room.
However, tees were installed so that additional suction points could
easily be added in this area later if necessary.
Communication testing in the 1957 four—room slab-on—grade addition at
the far west end of the building indicated that one suction point would
likely mitigate all four rooms since subslab barriers did not surround
every room as in the original building. A single suction point was
installed in Room 114 behind the door as shown in Figure 7.2.11. The 4
in. diameter Schedule 40 PVC pipe was run overhead across the classroom,
exited the room through the north exterior wall, and turned up the side
of the building. A single fan (Kanalflakt T3B Turbo,rated at 230 cfm at
1 in. WC) was mounted vertically just below the roof level. The fan
exhaust was directed over the roof to prevent possible reentrainment
into the building.
Visual alarms were installed for each of the fans. These included
pressure sensitive switches (model 2E462 Multi Purpose Air Switch, W.W.
56
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Grainger, Inc.) with red and green indicator lights. The operation of
these alarms is such that, if the fan is running and providing negative
pressures, the green light is on, and if the fan stops or the negative
pressure is less than about -o.l in. WC the green light goes out and the
red light turns on. If all power is lost to the mitigation fans, both
lights go out. In either a no-light or red-light condition the school
maintenance staff has been instructed to call the Nashville Metro
Operations Office.
7.2.7 Results of Initial Mitigation System
A Pylon CRM (AB5 with PRD1 passive cell) was placed in Room 120 on
July 31, 1989, at about 1 pm before the ASD fans were turned on. The
results are shown in Figure 7.2.12 where the hourly radon levels are
plotted as a function of time. Within about 19 hours the radon levels
reached a peak of 69.2 pCi/L and then started dropping. The length of
time before the ASD fans were turned on was not sufficient to establish
an average radon level; however, based on CC measurements, the radon
levels vary between about 4 0 and 90 pCi/L. The ASD fans were turned on
at 2:10 pm on August 1, 1989, and the radon levels in Room 120 began to
drop immediately. Within about 24 hours the radon levels appeared to
reach a stable level of approximately 2.5 pCi/L as shown in Figure
7.2.12.
Subslab pressure field measurements were repeated on August 4 using
the ASD fans as the source of depressurization. The flow rates of the
fans and the pressures at the suction points were also measured. The
results are shown in Figure 7.2.13.
In the four-room addition at the west end of the building, excellent
subslab depressurization was measured in each of the four classrooms
(Rooms 112, 113, 114, and 115). This confirmed the communication
diagnostic predictions that a single suction point would provide
adequate subslab coverage for all four classrooms.
In the main portion of the original building, the subslab
depressurization in the rooms with the two multi-point ASD systems was
fairly good in those rooms that had a suction point, but
marginal-to-poor in those rooms that did not. However, before
additional suction points were added to the systems, the effects of the
initial system configuration were measured with CC detectors.
Mitigation installation was completed the first week of August 1989,
with all systems operational. The following weekend all rooms in the
school were tested with CC detectors under closed conditions with the
HVAC system off. These tests were carried out by the Nashville Metro
staff. The results are shown in Table 7.2.1 and Figure 7.2.14. The
school average radon level was 2.0 pCi/L with a maximum of 4.0 pCi/L in
Room 117 and a minimum of 0.8 pCi/L in the teachers' lounge. The
results of the mitigation systems are summarized in Figure 7.2.15 where
the July pre-mitigation results are compared to the August
post-mitigation measurements.
57
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Based upon these measurements it appeared that the ASD systems are
adequately controlling the radon levels in the slab-on-grade portions of
the school during the warmer months.
The levels measured during the August tests in the rooms located over
the crawl space were the highest found. These classrooms need to be
addressed separately wxth a dxfferent mitigation system , most lilcely a
sub-membrane depressurization system. Mitigation of these rooms will be
EPA's first detailed study of a school building built over a crawl
space. This quadrangle of rooms is ideal for these investigations since
they are relatively small and fairly isolated from the slab-on-grade
rooms and the crawl space headroom is adequate and contains no asbestos.
7.2.8 Additional Phases of Diagnostics and Mitigation
This school was retested during colder weather the week of December
1-4, 1989, with results shown in Table 7,2.1 and Figure 7.2.16. Radon
levels had increased significantly to a building average of 6.5 pCi/L
with a low reading of 1.4 pCi/L in Room 114 and a high reading of 40.4
pCi/L in Room 120. The higher readings were measured in Rooms 109, 110,
and 120.
The ASD systems were thoroughly reexamined on January 3 through 5,
1990, and additional diagnostic tests were carried out to identify
problems. It was found that the suction pipe in Room 109 had been
1 -*-t -j "I "I 1 +¦ y—» i w i m4— « +¦ l—i a CSf*l1 *1 23 4-" 4» V* a +• a i ¦* mm m « 4-
JL J J> %¦« G JLi «l* Vwi .tjL, Vv imt JL J <1 • JL JL li a xS hmSp Iht JL JL Q. W JL CH2 V** V*. Jlil KJ JL it jtCw 23 «Jl w* -JL Jl JL L/ jL. j
cutting off nearly all flow into this pipe. This resulted in no subslab
depressurization in Room 109. Some marginal depressurization was
measured in Room 110 (no suction point yet installed in this room) ;
however, this was probably due to the suction point in Room 111 rather
than that in Room 109. Because of the poor communication between Rooms
109, 110, and 111, it was decided to add a suction point in Room 110 in
addition to correcting the problem with the suction point in Room 109.
It was also thought that the elevated level in the office was probably
due to the failure of the suction point in Room 109.
In Room 120, two steam pipes were found behind a wooden wall coming
through a 2 ft by 2 ft opening in the slab. This opening in the
northwest corner of the room had not been located during earlier
investigations. The opening was carefully sealed with concrete to
eliminate this major radon entry point. After sealing the steam pipe
entry hole, the subslab communication was remeasured in Room 120 using
the suction point in the southeast corner of the room as a source. The
communication was still found to be only marginal in the northwest
corner of the room.
The radon level measured xn Room 107 durxng the December 1989 tests
was 4.6 pCi/L. This elevated level, combined with the very low
depressurization that was measured in August (see Figure 7.2.13) led to
58
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procedure.
All interior walls in the original building of School I extended
through the slab footings. This resulted in a compartmentalized subslab
area equivalent to the room configuration of the school. In addition,
the aggregate had a smaller average particle size and contained more
fines. As a result of these two factors, subslab communication was
found to be much poorer than at School H. PFE was limited to a maximum
of about 30 ft. Mitigation was accomplished with three suction systems
containing 16 suction points. The average radon level in School I was
reduced from 29.7 to 1.7 pCi/L.
The comparison of results in these two schools shows a dramatic range
of how effective subslab depressurization can be in schools. In School
H, the north wing has one suction point which is mitigating all the
rooms in this wing to 1.3 pCi/L or less over 15,000 sq ft. In
comparison, School I contains about 15,000 sq ft, and to reduce levels
to an average of 1.7 pCi/L required 16 suction points on three fan
systems. Both schools had coarse aggregate under the slab. School H
had a coarse aggregate containing few fines and appears relatively deep
and uniform in its application. Examination of the aggregate under
School I showed that it was a naturally occurring coarse aggregate.
However, in several suction holes in School I the thickness of the
aggregate was less that l in. ar»-" in some places a great deal of clay
was mixed into the aggregate. Consequently, it was felt that a large
difference of the poor PFE of the subslab systems in School I was the
result of improper installation of the aggregate, not in the aggregate
itself. These conclusions are based on communication measurements with
both the suction point and the test point within the same room. School
I has the additional problem of having many subslab walls which serve as
barriers to PFE.
7.3 SCHOOL J
This elementary school is approximately 6 miles southwest of School
I. Several of the houses included in the EPA Nashville Radon Mitigation
Demonstration are within 1 to 2 miles of the school.
7.3.1 Building Description
This school has 19 classrooms, a multi-purpose cafeteria/auditorium,
a kitchen, several offices, and a teachers' lounge. The total floor
space of the school is approximately 34,000 sq ft. The original
building was constructed in 1954 and six rooms were added in 1957. The
original building is slab-on-grade construction, and the 1957 addition
included a below-grade basement of about 2,300 sq ft and an adjacent
crawl space of approximately 1,600 sq ft. The layout of the school is
shown in Figure 7.3.1.
7.3.2 Pre-Mitigation Radon Measurements
CC screening measurements were made by school personnel during
60
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February 1989. The locations of the CCs are shown in Figure 7.3.2.
These numbers are used instead of the classroom numbers because of the
ambiguity of the room numbering system used in the school. The results
of the radon screening measurements are shown in Figure 7.3.3 along with
follow-up measurements made in selected rooms during the same month.
Additional CC measurements were carried out during July 1989, and these
results are shown in Figure 7.3.4. All of the CC measurements are
summarized in Table 7.3,1.
For the screening measurements made during February 1989, the school's
average radon level was 29.4 pCi/L with the highest value of 81.9 pCi/L
measured in a classroom on the west side of the building (CC No. 3) .
The lowest value measured was 4.1 pCi/L in one of the 1957 addition
classrooms (CC No. 6) located over the basement room. Follow-up CC
measurements were carried out during the same month in selected rooms.
These follow-up measurements were carried out in the four classrooms
with the highest levels (CC Nos. 2, 3, 10, and 11) and in one of the
offices (CC No. 23). The average of these follow-up measurements was
30.9 pCi/L and agrees quite well with the previous measurements.
An additional set of CC measurements were carried out in July 1989 by
the school board personnel. These results are shown in Figure 7.3.4 and
are summarized in Table 7.3.1. The average school radon level during
this set of measurements was only 9.6 pCi/L with the highest value of
47.6 pCi/L measured in the same classroom as found during the February
1989 measurements (CC No. 3). The lowest value measured in July 1989
was 0.5 pCi/L in the boiler room.
The two sets of CC measurement data are plotted in Figure 7.3.5 where
the readings taken in July were plotted as functions of the February
values. The number associated with each data point is the corresponding
CC location number. Correlation between the two data sets is not
extremely good. In general the July values were only about 26 percent
of the values measured in February. One interpretation of these results
is that the weather conditions were very different during the two
testing periods. The average ambient temperature was 39.0°F during
February 1989, whereas it was 79.1°F during July 1989. Thus, the
differences may be due to a reduced stack effect.
7.3.3 Building investigation
The major part of the school is slab-on-grade with the remainder
including both basement and crawl space construction. The highest levels
found in both February and July were in Room 3. This room is the end
room of the original building and is adjacent to the crawl space added
in 1957. It is probable that radon from the exposed soil in the crawl
space is entering the room through cracks in the slab/wall joint along
the north end of the room.
The building construction includes below-grade walls as shown in
Figure 7.3.1. These walls are of concrete block and may not be sealed
below the soil. Observation of the walls in the crawl space shows no
61
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evidence of wall sealing. The design drawings were not available at the
time of diagnostic testing; as a result, no information was available
regarding the material under the slab. During the diagnostic tests,
holes drilled through the slab indicated that some aggregate was
present, but the type and depth were not determined. Cracks in the
slab-to-wall joint were observed at several locations in the school.
Some of these cracks were as wide as 1/2 in.
7.3.4 HVAC System and Pressure Differentials
The school heating system uses hot water and radiant heaters along the
exterior walls of each classroom. Cooling during the summer months is
provided by window-mounted air-conditioners in each classroom. There is
no provision in any of the rooms for fresh air intake other than through
infiltration. No interior-to-exterior pressure measurements were made
during the diagnostic tests.
7.3.5 Diagnostic Measurements
On June 29, 1989, SRI and EPA carried out diagnostic tests in the
school. During these tests, 14 small holes (3/8 in. in diameter) and
two large suction holes (1-1/4 in. in diameter) were drilled through the
slab. The locations of these suction and test holes are shown in Figure
7.3.6. Prior to the subslab communication tests, the radon levels under
the slabs were measured at each slab penetration. Measurements were
made with a Pylon AB5 operating in the sniff mode. The resulting
subslab radon levels are shown in Figure 7.3.7 and summarized in Table
7.3.1. The average level under the slab was only 296 pCi/L with a high
value of 845 pCi/L under the slab of Room 3 (the room that consistently
tested highest) and the lowest value of 76 pCi/L under Room 14. In an
effort to observe any correlation between the subslab levels and those
measured in the classrooms, the room radon levels measured in February
and July were plotted as functions of those measured in June. The
results are shown in Figure 7.3.8. The room radon levels show increases
with higher subslab radon values. However, the correlation (linear
least squares) is fairly low as shown in Figure 7.3.8.
The results of the subslab communication tests are shown in Figure
7.3.9. The PFE under the slab was excellent as long as no below-grade
walls were in the way. For the suction point located in Room 14 in the
east wing of the school and a suction pressure of -2 in. WC, the PFE in
the east-west direction could be measured as far as 60 ft from the
suction point. However, in the north-south direction, the air flow
encounters below-grade walls along each side of the hallway. In this
direction the extension was reduced to 30-40 ft or less. In the north
wing of the school, the pressure field was easily measured 25 ft from
the suction point in a north-south direction and somewhat less across
the hallway. The extension was probably greater than measured; however,
Rooms 4 and 9 are located above the crawl space.
In summary, the communication under the slab was found to be quite
good. This should allow for simpler subslab depressurization than for
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School I (Section 7.2).
7.3.6 Mitigation Strategy
Because of the shape and length of the school geometry, two ASD
systems are recommended as shown in Figure 7.3.10. The system on the
east wing of the school would include a 6 in. diameter, Schedule 40, PVC
main running the length of the east-west corridor. This pipe can be
installed above the ceiling tile in the hallway and the 4 in. diameter,
Schedule 40, PVC drops to the suction points can join the 6 in. main in
the hallway. The 4 in. suction pipes should enter the classrooms above
the ceiling tiles and drop to the slab penetrations. The system for the
north-south wing is a little more complex in that it must include the
basement rooms on the north end of the building. The suction pipe for
basement Room 7, can be located outside of the building and enter the
lower level just above grade level. Both systems should be
depressurized using fans rated at about 410 cfm at 1 in. we. Additional
details of this system are shown in Figure 7.3.11.
In both of the 6 in. mains in the corridors, capped tees should be
installed so that additional suction points can be added later if
necessary (except for Rooms 4 and 9 over the crawl space). The added
cost of installing the extra tees is much less than retrofitting them
later. The ASD system details discussed in Section 4.1.7 should be
followed.
The crawl space will also need to be considered for mitigation. The
most successful mitigation system for the crawl space would likely be
a sub-membrane depressurization system. Here, a layer of durable
plastic membrane is place over the exposed soil with one or more suction
points exhausting the region under the plastic as shown in Figure
7.3,12. The intent of the system is to remove the radon-laden soil gas
before it enters the crawl space. The membrane material should have
adequate tear and puncture resistance and be stable with regards to low
temperatures and ultraviolet exposure. One such material that has been
used in residential houses is 4 mil thick, two-ply, cross-laminated,
high-density polyethylene. If this type of system is needed, the
suction can be provided either by a separate fan or by a slipstream from
the ASD system.
Another less expensive but more experimental school crawl space
mitigation option could be depressurization of the crawl space region
with a fan (e.g., a fan rated at 230 cfm at 1 in. WC). This technique
involves inserting a 4 in. diameter Schedule 40 PVC pipe through an
exterior opening to the crawl space (e.g., a crawl space vent), with the
fan attached to the top of the pipe exhausting at roof level. Depending
on the crawl space size and tightness, it may be necessary to seal
openings in the crawl space and/or to distribute the depressurization
via a network of pipes within the crawl space.
The efficiencies of the system will be improved if all cracks in the
slab and slab/wall joints are caulked with urethane. Sealing is
63
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particularly important in Rooms 3, 4, 9, and 10 where the cracks lead
into the crawl space.
7.3.7 Estimated Cost
It is difficult to estimate the cost of the mitigation systems
described above. However, the installed systems will probably run in
excess of $25,000 even if the school maintenance staff does the
installation.
7.3.8 Summary
This school has provided another example of construction techniques
that will have to be addressed in order to mitigate public buildings
that were not designed with a radon problem in mind. The existence of
slab-on-grade, crawl space, and basement construction in a single
building should not present insurmountable difficulties if provisions
are made in the mitigation system design.
There are no plans for additional diagnostics to be carried out in
this building unless the post-mitigation CC measurements indicate a
problem.
7.4 SCHOOL K
This elementary school is located approximately 1-1/2 miles from
School J in the southeastern portion of Nashville. The school is also
located within 2 to 5 miles of houses that were included in the EPA
Nashville Radon Mitigation Demonstration. Houses in this area are known
to have a potential indoor radon problem.
7.4.1 Building Description
This school has 23 classrooms, an office/teachers' lounge/clinic, a
library, and a combination auditorium/cafeteria with separate kitchen
and storage rooms. The total floor space of the building is
approximately 31,600 sq ft, composed of 23,780 sq ft of slab-on-grade
construction, and about 7,820 sq ft of classrooms built over crawl
space. The original building of approximately 12,390 sq ft was
constructed, in 1960. In 1961 an additional 11,400 sq ft of classroom
space was added at the ends of the original building* The final
addition was in 1963 when six classrooms, boys' and girls' restrooms,
and a storage room were added to the northeast wing of the building.
This last addition was constructed using a slab-over-crawl space design
with the top of the slab at the same elevation as the rest of the
building. The layout of the original building and the various additions
are shown in Figure 7.4.1. The room numbers are shown in Figure 7.4.2.
7.4.2 Pre-Mitigation Radon Measurements
CC screening measurements were carried out by personnel of the school
board during February 1989. The locations of the CC number designations
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are shown in Figure 7.4.3. The results of the February screening
measurements (and the follow-up measurements in selected rooms) are
shown in Figure 7.4.4. These and subsequent radon measurements are
summarized in Table 7.4.1. For the original screening measurements, the
school average radon level was 15.4 pCi/L with the highest level of 70.1
pCi/L measured in Room 14 in the outer portion of the northeast wing.
This room is at the end of the original building in this wing. The
lowest level of 1.2 pCi/L was measured in Room 4 which is also one of
the end rooms in the northwest wing of the original structure.
Follow-up measurements were carried out in the three rooms with the
highest levels in the screening tests. These follow-up measurement
levels were only 50 to 75 percent of the previous levels. No
explanation is evident at this time for the lower readings. Presumably,
both the February 1989 screening and follow-up measurements were carried
out with the existing sub-slab depressurization systems (installed in
August 1988 and discussed below) operating.
Additional CC measurements were carried out in July 1989. The results
are shown in Figure 7.4.5 and are summarized in Table 7.4.1. The
school's average radon level measured in July was 7.4 pCi/L with the
highest level (22.5 pCi/L) measured in Room 15 and the lowest level of
0.5 pCi/L in Room 20. It is interesting to note that Room 15 is
directly across the hall from Room 14 which measured highest in
February. The results of the July CC measurements have almost no
correlation with the CC results in February. The two sets of data are
shown together in Figure 7.4.6. Here it can be seen that the rooms
tested highest in February were in general the lowest in July. This is
probably related to the effects of seasonal ventilation in the crawl
space; however, no data are available to confirm this hypothesis.
7.4.3 Building Investigation
The original portion of the building is slab-on-grade construction
with a slab thickness of 4 in. and, according to the design drawings,
has 4 in. of unspecified gravel under the slab. It is not certain
whether this part has below-grade walls or not. The 1961 additions are
also slab-on-grade with below-grade walls and gravel under the slab.
The last (1963) addition is a slab-over-crawl-space with below-grade
walls. The height of the crawl space is about 1 ft. This limited
clearance will certainly affect the mitigation strategy for the crawl
space»
When SRI first visited the school on June 8, 1989, two previously
installed ASD systems were in operation. One system was installed in
the storage room between Rooms 3 and 5 and the other system in a similar
room between Rooms 17 and 19. The fans used in both systems were
Cincinnati Fume Master, Model 500S (1/2 hp, 3450 rpm, 370 cfm) typically
used as exhaust systems in welding operations. The first system
(between Rooms 3 and 5) was a true ASD system. No estimate was made as
to the suction pit size under the slab if indeed there was one. The
second system (between Rooms 17 and 19) was unfortunately installed over
the crawl space and acting as a forced ventilation system for the crawl
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space. As will be described later (Section 7.4.5), the pressure at the
fan inlet just above the slab penetration was -4.46 in. WC for the first
system and -1.80 in. WC for the system over the crawl space. These
systems were installed in August 1988 by the school's maintenance staff.
Investigation of the building revealed numerous openings at slab
expansion joints and at the slab/wall junction. There were also
plumbing and utility lines under the slab in most of the classrooms.
7.4.4 HVAC System and Pressure Differentials
The building is heated with hot water radiant' heaters along the
exterior walls of each room. No provisions were made in the system to
provide fresh air ventilation. Most of the rooms had window-mounted
room air-conditioners. The front office/teachers' lounge/sick room
complex (CC Nos. 1, 2, 3, and 4) had a central heating and cooling unit
with gravity returns through the door vents. The unit had no fresh air
intake. No building pressure differentials were measured.
7.4.5 Diagnostic Measurements
On June 8, 1989, test holes were drilled through the slab in Rooms 2,
3, 5, 6, and 10, in the hall between Rooms 4 and 6 in the northwest
wing, in Rooms 17, 18, and 19, and in the hall outside Room 18 in the
northeast wing. The locations of these test holes are shown in Figure
7.4.7. The suction pressure for this series of subslab communication
tests was provided by the ASD systems described above. The results of
these tests are shown in Figure 7.4.8. For System 1, the pressure at
the suction point was -4.46 in. WC and the pressure field could be
measured as far away as Room 2, approximately 75 ft from the suction
point. This indicated that communication under the slab might be
excellent, at least for this wing. After telephone contact with the fan
manufacturing company, it was apparent that this fan is pulling very
1 i +-+- 1 A aii1* f TT51TI nndpr +-V\£> 1 4. JL. O JuwViiw -i- X £>
about -5 in. WC.
Since system 2 was not depressurizing under the slab, no pressures
were measured at any of the test points in the northeast wing other than
wind-induced pressures of about ± 0.003 in. WC. The flow rate of air
being extracted from the crawl space is about 200 cfm.
Following completion of the communication tests, the ASD fans were
turned off and the test holes were sealed with putty. After
approximately 4 hours radon sniff measurements were carried out in the
test holes in the slab. The subslab radon levels measured at the test
holes are shown in Figure 7.4.9 and are summarized in Table 7.4.1. As
might be expected, the levels under the slabs in the vicinity of System
1 were very low. This indicates that this system is removing some of
the radon under the slab. The subslab levels near System 2 are greater
since the ASD system is not pulling air from under the slab, but from
the crawl space.
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On July 6, 1989, the SRI team returned to the school to carry out more
diagnostic tests. Since the ASD systems had been off for approximately
4 weeks, the subslab conditions should have returned to something
approaching pre-mitigation conditions. Additional test holes were
drilled through the slab and four suction holes were installed as shown
in Figure 7.4.10. After drilling the holes through the slab, they were
sealed with putty until sniff measurements could be carried out at each
hole. The results of the subslab radon measurements are shown in Figure
7.4.11 and Table 7.4.1. Surprisingly, the levels were not much higher
than those measured in June for the same test points. Significantly
higher levels were measured in July but not at the same locations. The
school's average subslab radon was 122 pCi/L in June 1989 and 318 pCi/L
in July 1989. The highest level measured in the later tests was 1445
pCi/L under the slab of Room 10 in the northwest wing of the school.
The lowest level was 19 pCi/L measured in Room 3 also located in the
northwest wing. This is somewhat suprising since the sample taken in
Room 3 was in an interior location close to the corridor which would
presumably be less diluted than the sample taken in Room 10 (which is a
corner room).
Attempts to correlate the February and July 1989 CC measurements in
the rooms to the subslab levels measured in July 1989 were not very
successful. The results are summarized in Figure 7.4.12. The February
1989 data show a positive correlation to the subslab levels with a
correlation coefficient of about 0.4 (R2=0.24) . The July 1989 data have
only a slight positive correlation (R?=0.10) to the July subslab levels.
These results seem to be typical of other schools in which similar tests
have been carried out.
The results of the subslab communication tests are shown in Figures
7.4.13, 7.4.14, 7.4.15, and 7.4.16 for each of the four suction points
installed in the school. The results indicate that the subslab
communication is slightly better under the northwest wing of the
building than under the northeast wing. The PFE is summarized in Figure
7.4.17 where circles are drawn to show the approximate maximum distance
a depressurization could be measured with -2 to -4 in. WC suction. In
aeneral with fcvriical fan (•— 1 t"*** — 2 "in "nirfs-cicniTP
y C 1 JL. w. JL j W X tiAl V-J i. \m* Q. JL JL Q11 J^/i. w£3> £¦> UJ. C O ^ JL WW £» JL1 i » I * w f g LliC J~
field could be measured as far as 30 ft from the source. This could be
improved by excavating a suction pit in the soil under the suction
point. An area of 3 0 to 4 0 ft would be the distance covered by a given
sub-slab depressurization point. This coresponds to one suction point
for each two to four rooms.
7.4.6 Mitigation Strategy
Because of the shape and length of the school geometry, two ASD
systems are proposed as shown in Figure 7.4.18. The system on the
northwest wing of the school would include a fan (rated at about 410 cfm
at 1 in. WC) mounted at roof level and attached to a 6 in. diameter,
Schedule 40, PVC main running the length of the corridor. This pipe can
be installed above the ceiling tile in the hallway, and the 4 in.
67
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diameter, schedule 40, PVC drops to the suction points can join the 6
in. main in the corridor. The 4 in. suction pipes should enter the
classrooms above the ceiling tiles and drop to the slab penetrations.
Suction points should be installed in Rooms 2, 3, 5, 6, 8, and 9, and
the clinic. Provisions should also be made during installation for
suction points in the remaining rooms later if needed.
The system for the northeast wing should include a fan (rated at about
410 cfm at 1 in. WC) mounted at roof level and connected to another 6
in. main running down the corridor. Suction points should be installed
in Rooms 13, 14, 15, and 18, the library office, and the auditorium/
cafeteria.
In both of the 6 in. mains in the corridors, capped tees should be
installed so that additional suction points can be added later if
necessary (except for Rooms 19, 20, 21, 22, 23, and 24 over the crawl
space). The added cost of installing the extra tees, if ever needed, is
much less than retrofitting them later. The ASD system details
discussed in Section 4.1.7 should be followed.
The crawl space will also need to be considered for mitigation. One
simple method that might be tried in this limited access area is to
install two small fans (100-200 cfm) in the foundation vents, one on
each side of the crawl space. One of the fans should be orientated so
that it blows outdoor air into the crawl space and the other so that it
exhausts air. It would also be prudent to mask off part of the
exhausting fan so that the crawl space pressure is slightly positive
relative to the outdoor pressure (more air is injected than is
exhausted). Crawl space depressurization, as discussed in Section
7.3.6, might also be a mitigation option.
A more costly mitigation system for the crawl space may have to be
installed. The most successful technique would be a sub-membrane
depressurization system, as discussed in Section 7.3.6. However,
installation of such a system in this small crawl space would be very
difficult.
The existing ASD system in the northwest wing should be removed and
the slab hole sealed. The existing system in the northeast wing could
be left in place and operating until it is determined if a sub-membrane
depressurization system needs to be installed.
7.4.7 Estimated Cost
It is difficult to estimate the cost of the mitigation systems
described above. However, the installed systems will probably run in
excess of $25,000 even if the school maintenance staff does the
installation.
7.4.8 Summary
This school has provided another example of construction techniques
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that will have to be addressed in order to mitigate public buildings
that were not designed with a radon problem in mind. The existence of
slab-on-grade and crawl space construction in a single building should
not present insurmountable difficulties if provisions are made in the
mitigation system design. This school has also demonstrated the
possible errors that can be made in system design and installation when
close attention is not paid to the structural details of the building.
There are no plans for additional diagnostics to be carried out in
this building unless the post—mitigation CC measurements indicate a
problem.
7.5 SCHOOL L
This elementary school is located approximately 1 mile north of School
H in the eastern portion of Nashville. The school is also located less
than 1 mile from houses that were included in the EPA Nashville Radon
Mitigation Demonstration Project. This area is known to produce
elevated levels of radon gas in both houses and public buildings.
7.5.1 Building Description
The school was originally constructed in 1959 and contained 11
classrooms, an auditorium/cafeteria, a boiler room, and several offices
and work rooms. This portion of the existing building contained
approximately 21,200 sq ft of floor space as shown in Figure 7.5.1. In
1962 approximately 4,800 sq ft of classroom space (four classrooms} was
added to the east wing of the school and about 7,000 sq ft (six
classrooms) to the west wing. The existing school has a total area of
33,000 sq ft. The entire building uses slab-on-grade construction.
The school has utility tunnels under the outside edges of all the
rooms as shown in Figure 7.5.2. These utility tunnels are 4 ft wide and
4 ft high with what looks to be a dirt floor. The tunnels contain the
plumbing and sanitary lines for the building. The steam lines in both
the tunnels and the boiler room are asbestos covered and some appear to
be in a friable condition. The tunnels open into the boiler room and
each has an outdoor vent with horizontal grille at the ends of the
building. At the first visit to the school in June 1989 a previously
installed fan was operating in the boiler room outlet of the tunnel
along the front of the school. This fan was pulling outdoor air through
the vents and through the tunnel along the front of the building and
exhausting the air into the boiler room. Here it is assumed that the
major portion of the air entered the rear tunnel and exited the building
at the other two vents. The specifications of the fan are not known;
however, based on the size of the fan, it is estimated that the flow was
about 500 to 1,000 cfm. The total volume of the utility tunnels is
approximately 16,540 cubic ft and, assuming a flow rate of 1,000 cfm,
the air exchange rate in the tunnels was in excess of 6 air changes per
hour (ACH).
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The room numbers and the numbers used to identify the CCs used in the
screening and follow-up measurements are shown in Figure 7.5.3. These
numbers are also shown in Table 7.5.1.
7.5.2 Pre-Mitigation Radon Measurements
CC screening measurements were carried out by personnel of the school
board during February 1989. The results of the February screening
measurements (and the follow-up measurements in selected rooms) are
shown in Figure 7.5.4. These and subsequent radon measurements are
summarized in Table 7.5.1. For the original screening measurements, the
school's average radon level was 14.1 pCi/L with the highest level of
40.3 pCi/L measured in Room 15 (CC No. 14) on the northeast corner of
the 1962 addition to the west wing of the building. The lowest level of
0.8 pCi/L was measured in Room 2 (CC No. 26) which is one of the
interior rooms in the east wing of the original structure. Follow-up
measurements were carried out in the three rooms with the highest levels
in the screening tests. These follow-up measurement levels were only 65
to 70 percent of the previous levels. No explanation is evident at this
time for the lower readings. It is not certain whether the fan
installed in the utility tunnel was in operation or not during this
period.
Additional CC measurements were carried out in June 1989. The results
are shown in Figure 7.5.5 and Table 7.5.1. The school's average radon
level measured in June was 18.0 pCi/L with the highest level (60.7
pCi/L) measured in Room 1 (CC No. 17) and the lowest level of 1.4 pCi/L
in the teachers' lounge (CC No. 4) . The results of the June CC
measurements have almost no correlation with the CC results in February.
The two sets of data are shown on a room-by-room basis in Figure 7.5.6.
Here it can be seen that the rooms tested highest in February were, in
general, more intermediate in value in June. Also, those rooms that
measured low in February were among the highest in the June results. It
is known for certain that the tunnel fan was off during the June
measurement period. This complicates any understanding of the seasonal
differences in the room radon levels,
7.5.3 Building Investigation
Both the original portion of the building and the additions are
slab-on-grade construction with a 4 ft by 4 ft utility tunnel around the
periphery of the building. The design drawings call for 4 in. of stone
under the slab of each of the rooms. The interior walls of the rooms
adjacent to the hallway are constructed on thickened slab footings. It
was not clear whether the aggregate extended under the thickened slab
footings. The utility tunnels contained heating pipes that were covered
with asbestos, some of which were in a friable condition. Numerous open
cracks were seen at the slab expansion joints and at the slab-to-wall
joints.
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7.5.4 HVAC System and Pressure Differentials
The building is heated with hot water radiant heaters along the
exterior walls of all rooms. A window-mounted air-conditioning unit is
also in each classroom. No provisions are made in the system to provide
fresh air other than infiltration. Although no inspection was done in
the utility tunnels, it is very likely that there are cracks around the
heating pipes that come up out of the tunnel. This can be a significant
source of radon infiltration. No building pressure differentials were
measured.
7.5.5 Diagnostic Measurements
On June 29, 1989, a team from SRI visited the school to carry out
diagnostic tests of both the subslab radon levels and the subslab
communication. Testing was continued on June 30, but not completed. A
second visit was made on July 5, 1989, to complete the diagnostic
measurements. The results from these visits are discussed below.
Four suction holes (1-1/4 in. in diameter) and 26 test holes (3/8 in.
in diameter) were drilled through the slabs in the schools. The
locations of the suction and test holes are shown in Figure 7.5.7.
The slab penetrations were closed with rope caulking as soon as they
were drilled. This was to preserve, as nearly as possible, the
conditions under the slabs. Each hole was tested with a Pylon AB5
operating in a sniff mode. The results of these measurements are shown
in Figure 7.5.8 and Table 7.5.1.
The average subslab radon level was 640 pCi/L with a low of 48 pCi/L
measured under the south storage room and a high of 2460 pCi/L measured
under Room 3 (CC No. 18). In an attempt to correlate the subslab radon
levels to the room radon levels, linear regression calculations were
carried out using the three sets of data. The results are plotted in
Figure 7.5.9. The June CC data show a modest correlation to the subslab
levels measured in June/July with a regression coefficient (R2) of 0.5,*
however, the February CC data showed a negative correlation to the
sub-slab levels. These results can perhaps be seen more clearly in
Figures 7.5.10 and 7.5.11 where the room and subslab radon levels are
plotted for each CC location. As seen in Figure 7.5.11, the highest
levels measured with the CCs also had the highest levels under the slabs
(CC Nos. 17, 18, 25, and 26). It would appear that there are seasonal
differences in both the room and subslab radon levels.
The results of the subslab communication tests are shown in Figures
7.5.12, 7.5.13, 7.5.14, and 7.5.15 for each of the four suction points
tested in the school. Suction point 1 (Figure 7.5.12) was in the closet
of Room 18 (CC No. 10) which is in the center of the 1962 addition to
the west wing of the school. The PFE from this point was much better in
the east-west direction (along the direction of the corridor) than in
the north-south direction. This is probably due to the lack of air
71
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passages under the thickened slabs along the classroom/corridor walls.
The pressure field extended for a distance of about 55 ft in the east-
west direction and only about 20 ft in the north-south direction.
Suction point 2 was in the closet of Room 12 (CC No. 7) in the
original part of the building as shown in Figure 7.5.13. The results
obtained here were about the same as at suction point 1. The pressure
field extended for a distance of about 60 ft along the axis of the
building and only about 20 ft across the axis. This is again probably
due to the footings under the corridor walls.
Suction point 3 was in a closet of Room 4 (CC No. 25) in the east wing
of the original building as shown in Figure 7.5.14. As before, the
communication was much better in the east-west direction than the north-
south direction. Reliable pressure fields could be measured for a
distance of about 60 ft in the east-west direction and only 30 ft in the
north-south direction. Again, the reason is probably due to the subslab
footings.
Suction point 4, shown in Figure 7.5.15, was in the closet of Room 7
(CC No. 20) in the 1962 addition to the east wing of the building. The
communication under the slab from this location was not very good in
either direction but marginally better in the east-west direction. A
pressure field could be extended for a distance of about 30 ft along the
axis of the building but only about 15 ft across the axis.
The PFEs from all of the suction points are summarized in Figure
7.5.16. From this figure it is apparent that suction points will have
to be added about every second or third room and on both sides of the
corridor.
7.5.6 Mitigation Strategy
Based on the PFEs in Figure 7.5.16, the mitigation systems shown in
Figure 7.5.17 are proposed for this school. Two fans (rated at about
410 cfm at 1 in. WC) should be used, one for each wing of the building.
The fans should be connected to 6 in. diameter, Schedule 40, PVC pipe
running the full length of each corridor. This 6 in. main duct can be
located either above or below the ceiling tile in the corridor. The
connections to the suction points in the classrooms should be 4 in.
diameter, Schedule 40, PVC pipe. In the west wing, suction points
should be installed in the closets of Rooms 20, 15, 16, and 11, and in
the northeast corner of the library. In the east wing, suction points
should be installed in a closet of Rooms 3, 5, and 9, in the northeast
corner of Room 4, and in the northwest corner of Room 10.
Using the pressure field limits measured during the diagnostic tests,
the approximate subslab coverage that can be expected from these suction
points is shown in Figure 7.5.18. This figure shows some overlapping of
the subslab depressurization coverage. It is possible that, when 4 in.
suction points with pits in the soil are installed, the coverage will be
redundant. However, the system is designed slightly on the liberal side
72
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in terms of the number of suction points to reduce the possibility of
having to add additional points later. The ASD system details discussed
in Section 4.1.2 should be followed.
The efficiencies of all the systems will be improved if all cracks in
the slab and slab/wall joints and openings that lead into the utility
tunnel are caulked with urethane.
7.5.7 Estimated Cost
It is difficult to estimate the cost of the ASD systems described
above. However, the installed systems will probably run in excess of
$25,000 even if the school maintenance staff does the installation.
7.5.8 Summary
This school has provided another example of construction techniques
that will have to be addressed in order to mitigate public buildings
that were not designed with a radon problem in mind. The existence of
the utility tunnel poses a unique problem that has been identified in
many other schools. While it is tempting to use the tunnel as part of
the mitigation system, there may be other conflicting factors that need
to be considered. In this school, the existence of asbestos in the
tunnel precluded its use as a means of removing the radon from the
classrooms. Even if there were no asbestos in the tunnel, it is
possible that depressurizing the tunnel or using it to ventilate the
areas under the classrooms could lead to other problems. Thus, before
using the tunnel as a means of mitigation, additional research should be
carefully undertaken to determine the effects upon the remainder of the
building.
There are no plans for additional diagnostics to be carried out in
this building unless the post-mitigation CC measurements indicate a
problem,
7.6 SCHOOL M
This elementary school is located approximately 2 miles west of School
I in the south central portion of Nashville. The school is also located
within 5 to 8 miles of houses that are known to have elevated levels of
radon.
7.6.1 Building Description
This school building was originally constructed in 1950 with
approximately 16,500 sq ft of slab-on-grade classroom, office, and other
use space. In 1953 a two-story structure was added to the northwest end
of the school. In this structure, approximately 5,400 sq ft of
classroom space was added: half of this space was slab-on-grade and the
remainder was on the second floor. In 1964, 5,200 more sq ft of
classroom space was added using slab-over-crawl-space construction. In
1965, 4,800 more sq ft of space was added to the crawl space classrooms
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using the same construction, and a small area (800 sq ft) was added to
the kitchen. The additions and dates are shown in Figure 7.6.1. The
total area of slab-on-grade space is approximately 20,000 sq ft and the
slab-over-crawl-space areas are about 10,000 sq ft. The room numbers
and identifications along with the numbers used to identify the CCs used
during radon testing are shown in Figure 7.6.2. Notice that, in Figure
7.6.2. and all successive figures, the second floor rooms have been
deleted for clarity.
7.6.2 Pre-Mitigation Radon Measurements
CC screening measurements were carried out by school personnel during
February 1989. The results of the February screening measurements (and
the follow-up measurement in selected rooms) are shown in Figure 7.6.3.
These and subsequent radon measurements are summarized in Table 7.6.1.
For the original screening measurements, the school's average radon
level was 16.9 pCi/L with the highest level of 54.4 pCi/L measured in
Room 107 at the southeast end of the original building. The lowest
level of 3.4 pCi/L was in Room 117 in the 1965 slab-over-crawl-space
addition. In the follow-up measurements, five rooms were retested: Room
107 again had the highest level (36.1 pCi/L). The follow-up
measurements show excellent correlation to the levels obtained during
the initial screening measurements. The follow-up levels were on the
average about 73 percent of the initial values.
Additional CC measurements were made in July 1989. The results of
these measurements are shown in Figure 7.3.4 and Table 7.3.1. The
school's average radon level measured in July 89 was 8.1 pCi/L with the
highest level of 23.1 pCi/L measured in Room 107 (the same room as
before) and the lowest level of 0.5 pCi/L measured in Room 118 (the end
room over the crawl space). The two sets of CC data are shown in Figure
7.3.5 and show a fairly high correlation. The data are replotted in
Figure 7.3.6 to show this correlation. In Figure 7.3.6 the index of
correlation (R2 value) was found to be about 0.6 which is one of the
highest found to date in the school measurements.
The radon levels in the rooms over the crawl space were about the same
during both the February and July measurements. In February the levels
averaged 4.7 pCi/L and in July, 3.9 pCi/L. There are apparently some
seasonal differences in these levels.
7.6.3 Building Investigation
The major construction types used in the various additions were
described above. The building design drawings were not available when
diagnostic testing was conducted at the school; consequently, no
information was available regarding the subslab conditions. During the
diagnostic testing, holes were drilled through the slab at several
locations. Inspection of the subslab regions through these holes
indicated the presence of some aggregate containing fine clay under the
slabs. Inspection in the various classrooms indicated that there were
74
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substantial open cracks at the slab/wall junctions. There were also
utility pipes under the slabs in the hallways and under some of the
classrooms.
The crawl space areas were in general open and fairly clear of
obstructions. There was a single access door to the crawl space and
several foundation wall block vents. These vents were approximately 8
in. by 16 in. and most were open. Ventilation of the crawl space
depended on prevailing wind magnitude and direction. The degree of
ventilation is apparently inadequate based upon the radon levels
measured in the rooms above the crawl space.
7.6.4 HVAC System and Pressure Differentials
The school is heated with radiant hot water units located along the
outside walls of each room. The rooms are cooled during the warmer
months with window-mounted air-conditioning units. No evidence was
found for controlled outdoor air intakes. The kitchen and cafeteria
contained exhaust fans for ventilation, but makeup air depends on leaks
in the building shell. Building pressure differentials were not measured
during the diagnostic visit.
7.6.5 Diagnostic Measurements
On July 10, 1989, investigators from SRI, EPA, and the Nashville Metro
Departments of Schools and Health carried out diagnostic measurements on
the school building. During this visit, the subslab radon levels were
mapped and the subslab communication was measured at test holes drilled
through the slab. Twenty test holes (3/8 in. in diameter) and five
suction holes (1-1/4 in. in diameter) were drilled through the slab at
the locations shown in Figure 7.6.7. Prior to the subslab communication
tests, the radon levels under the slab were estimated by sniff
measurements with a Pylon ABB radon monitor at each penetration. The
radon levels measured are shown in Figure 7.6.8 and Table 7.6.1. The
average subslab radon level was 287 pCi/L and ranged from 60 to 780
pCi/L, The highest level (780 pCi/L) was measured under the slab in
Room 107, the same room that consistently tested high in the CC
measurements.
To compare the subslab levels with the levels measured in the rooms
above, linear regressions were calculated on the data. The results are
summarized in Figure 7.6.9 where the room CC data are plotted as a
function of the levels under the slab. The correlation between the
subslab results and the February 1989 CC data is higher (R2=0.5) than
between the subslab and the July 1989 CC data (R2=Q. 2) . As was the case
for previous school data, the correlation is not as high as one might
expect. However, the data sets were not obtained in a controlled manner
and there are large uncertainties as to the exact locations of the ccs
and the room conditions during each test.
75
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The results of the subslab communication tests are shown in Figures
7.6.10, 7.6.11, 7.6.12, 7.6.13, and 7.6.14. In Figure 7.6.10, the
communication under the 1953 addition of rooms was fairly good from
Suction point 1. Since the slab for these rooms (Rooms 101 and 102) was
about 4 ft below that for the rest of the school, the pressure field did
not extend to any of the rooms (Rooms 103 and 104) on the main level of
the school. This lower level is at or above grade on the north side and
below grade on the south end by about 4 to 5 ft. In designing the
mitigation system for the building, this addition will have to be
addressed separately from the rest of the building.
Suction point 2 was in the cloak room of Room 104, as shown in Figure
7.6.11. The communication in this part of the building was also fairly
good. From this location, the pressure field under the slab extended to
the hall in front of the offices. However, it did not extend to the
auditorium. No pressure field could be measured in the center of this
slab. The auditorium slab was at a lower level than the remainder of
the school and may explain the difficulty in producing a field in this
location from the suction point in Room 104.
Suction point 3 was located in the stairwell onto the auditorium stage
as seen in Figure 7.6.12. From this location, pressures could be
measured in the center of the auditorium with a suction pressure of -6
in. WC. In the eastward direction, the pressure field could be
measured as far as the offices at a suction pressure of -10 in. WC.
However, no pressure field could be measured in Room 105.
Suction point 4 was located just behind the door to the front office
as shown in Figure 7.6.13. From this point, the pressure field could be
measured into Room 105 but not as far as Room 107.
Suction point 5, shown in Figure 7.6.14, was located in the book room
at the east end of the east-west hallway. From this point the
communication was excellent over most of the eastern portion of the
original building. Exceptions to this were the center of Room 107 and
the work room north of the library (Room 109A).
The approximate PFEs are summarized in Figure 7.6.15 where closed
curves have been drawn about each of the suction points to indicate the
areas covered. The main areas not covered are the south end of the
auditorium and most of Room 107.
7.6.6 Mitigation Strategy
Based on the results of the subslab communication tests, the
mitigation system shown in Figure 7.6.16 is proposed for this school.
For the 1953 addition of rooms (Rooms 101 and 102) a single fan (rated
at about 230 cfm at 1 in. WC) mounted vertically at or near roof level
with a single suction point in the closet of Room 102 is recommended.
The piping can be 4 in. diameter, PVC, Schedule 40 exiting the room on
the west side of the building. The fan should be mounted at or near
roof level with the exhaust directed over the roof and away from any air
76
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The second system should include a single fan (rated at about 230 cfm
at 1 in. WC) mounted vertically at or near roof level on the west side
of Room 104« This system should use 6 in. diameter, schedule 40 PVC
pipe instead of the smaller pipe, because of the higher air flow that
will likely develop. This system may cover part of the auditorium but
will not be able to overcome the effects of the exhaust fans that are
likely to be operated in both the kitchen and the auditorium. However,
this may not be a problem in view of the time spent in this part of the
school by students and staff.
The third system should be located on the east side of the building
and should use, as a minimum, a fan rated at about 410 cfm at 1 in. WC.
The fan should be mounted vertically at or near roof level outside of
the teachers' lounge. The main suction point should be in the book room
using 6 in. diameter, Schedule 40 PVC pipe throughout. The slab
penetration should be at least a 6 in. diameter hole (and for ease of
installation should be 7 in. in diameter) with as large a pit under the
slab as possible. Because of the difficulty of producing a pressure
field in Room 107 and because of the consistently high levels measured
in this room, an additional suction point is suggested. The suction
point could be in the closet as shown in Figure 7.6.16. The ducting
could be 4 in. diameter, Schedule 40 PVC tapped into the system at any
convenient location using a 6 x 4 in. tee. The suction point in Room
107 should use a 5 in. diameter cored hole in the slab, with a suction
pit in the soil under the slab penetration. The ASD system details
discussed in Section 4.1.7 should be followed.
The crawl space may also need to be considered for mitigation, and the
recommendations discussed in Section 7.3.6 should be followed.
7.6.7 Estimated Cost
It is difficult to estimate the cost of the mitigation systems
described above. However, the materials alone will probably run in
excess of $25,000 even if the school maintenance staff does the
mstal lation-
7.6.8 Summary
This school has provided another example of construction techniques
that will have to be addressed in order to mitigate public buildings
that were not designed with a radon problem in mind. The existence of
slab-on-grade and crawl space construction in a single building should
not present insurmountable difficulties if provisions are made in the
mitigation system design. This school has also demonstrated that slabs
Mi 1 v*X- vwLi -X. JL JL. X- ft v* JL *--* V id. JLi IC. CJHLJli La, a 1.1* d ^ C3.2 ifhl Ilw
mitigation systems must account for this.
-------
There are no plans for additional diagnostics to be carried out in
this building unless the post-mitigation CC measurements indicate a
problem.
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SECTION 8
QUALITY CONTROL AND QUALITY ASSURANCE
8.1 INTRODUCTION
Since radon mitigation in schools is a new area of research, many of
the radon reduction techniques applied in these projects were
experimental. The diagnostic measurements needed to design such
mitigation systems were developed mainly on-site based on previous
experience in residential houses.
8.2 QUALITY ASSURANCE PROJECT PLAN
A Quality Assurance Pro^ect Plan (QAPP) was submitted in May 1989 for
the work performed by SRI. The QAPP was revised and updated in April
1990. Because of the experimental nature of the work described in this
report, an in depth QAPP was not appropriate. However, now that the
program is more mature, QA will be given greater emphasis in future
projects.
8.3 CHARCOAL CANISTER MEASUREMENTS
The most significant measurements carried out during the period
covered by this report were charcoal canister (CC) measurements. These
were short-term integrated radon measurements used to identify schools
and specific rooms in the schools with elevated radon levels. The CC
measurements were also used to assess the effects of various mitigation
approaches on the radon levels in the various rooms. With few
exceptions (as discussed below), the canisters were analyzed by EPA's
Eastern Environmental Radiation Facility (EERF)* in Montgomery, AL. Ten
percent of these canisters were deployed in the field as collocated
duplicate measurements of the precision obtained during the tests. The
CC results for Prince Georges County, MD, were obtained with detectors
from EERF, and the CC data from the two Washington County, MD, schools
were provided to EPA by the school officials. The February and March
1989 radon data from the Nashville, TN schools were obtained from
measurements carried out by EPA's Office of Radiation Programs, although
these canisters were also analyzed by EERF. The remainder of the CC
data were obtained from canisters provided by EPA's AEERL and analyzed
by EERF. The CCs were deployed and retrieved by various personnel.
The sections that follow discuss only those CC measurements where the
CCs were provided by EPA/AEERL and analyzed by EERF.
*Now designated the National Air and Radiation Environmental Laboratory
(NAREL).
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8.3.1 Assessment of Precision
Ten percent of the CCs were deployed as duplicate measurements. The
collocated detector results are listed in Table 8.3.1 along with: the
average value of each collocated pair, the standard deviation expressed
in picocuries per liter (pCi/L), and the coefficient of variation (CV)
expressed as a percentage for each set of measurements. The average of
the standard deviations for all of the measurements was 0.28 pCi/L with
the highest and lowest values of 3.6 and 0.0 pCi/L, respectively. The
average of the CV values for all of the measurements was 5.2 percent
with a maximum and minimum of 68.1 and 0.0 percent, respectively. The
average value of 5.2 percent for the overall CV was well within the
acceptable value of 10 percent even when the detected levels of less
than 4 pCi/L are included. When the detected levels of less than 4
pCi/L are eliminated, the average of the standard deviations drops to
0.21 pCi/L with a maximum and minimum of 3.6 and 0.0 pCi/L,
respectively, and the average of the CV values drops to 1.6 percent with
a maximum and minimum of 11.1 and 0.0 percent, respectively.
It is of some interest to compare the precision obtained from the
collocated CCs deployed in schools in each state. In Table 8.3.2 the
averages of the standard deviations and CV values along with the maximum
and minimum values are grouped by the state in which they were deployed.
Slightly more precision was obtained for the Maryland and New York
measurements than for the Alabama and Tennessee measurements.
The standard deviations of all the collocated detector pairs are
plotted as functions of the average values of the pairs in Figure 8.3.1.
Except for four collocated pairs of detectors, the standard deviations
are well within 1 standard deviation for all the duplicate measurements.
8.3.2 Assessment of Accuracy
No spiked measurements were carried out to assess the accuracy of the
CC measurements. Instead, the CC measurements in these projects relied
on the QA/QC checks carried out by the EERF laboratory.
8.3.3 Assessment of Completeness
Except for fewer than 10 CCs deployed, valid results were obtained.
This is well within a completeness criteria of 90 percent.
8.4 CONTINUOUS RADON MONITORS
Radon measurements with CRMs played only a small part in the
diagnostic tests conducted by SRI. In the SRI projects the CRMs were
not used to evaluate the effectiveness of the mitigation systems, but
more typically were used as sniffers for radon entry routes and subslab
radon levels.
80
-------
8.4.1 Assessment of Precision
No collocated CRM measurements were carried out due to limitations in
both time and instrument availability.
8.4.2 Assessment of Accuracy
The CRMs used by SRI in this study were calibrated in the EERF radon
chamber in June 1988, November 1989, and February 1990. Background
checks of the instruments were carried out both before and after each
field use. The aver age background counts were subtracted from the gross
field counts before the radon levels were calculated.
8.5 AUDITS
No EPA or SRI field audits were conducted during the period covered
by this report.
81
-------
SECTION 9
REFERENCES
1. Radon Reduction Techniques in Schools - Interim Technical
Guidance, U.S. EPA, EPA-5 20/1-89-020 (NTIS PB90-160086),
October 1989.
2. Radon Measurements in Schools - An Interim Report, U. S. EPA, EPA-
520/1-89-010 (NTIS PB89-189419), March 1989.
3. ASHRAE Standard 62-1989. Ventilation or Acceptable Indoor Air
Quality, ASHRAE, Atlanta, GA, 1989.
4. Summary Report of the Tennessee Radon Survey. Tennessee
Department of Health and Environment, Division of Air Pollution
Control. Nashville, TN, August 1987.
82
-------
APPENDIX A
FIGURES
A-l
-------
1861
ADOITlON
1S63
ADDITION
1849
ORIGINAL
BUILDING
UTlUTr
TUNNEL
SCALE:
100'
Figure 4.1.1 Floor plan showing additions at School A.
O
-------
SCALE, 100'
Figure 4.1.2 June 1989 follow-up measurements, School A,
pCi/L.
A-3
-------
Figure 4.1.3 Location of canister numbers for CC measurements in School A.
A-4
-------
Figure 4.1.4 Results of October 1989' CC measurements with HVAC
off in School A, pCi/L.
A-5
-------
T
N
THICKENED sub footings
utility
TUNNEL
SCALE; i— 100' H
Figure 4.1.5 Location of chickened slab footings in School A.
A—6
-------
D~
\
SOIL SAMPLE
WDS AT r.2',AND 2'9" DEPTHS
T
N
_SOlL SAMPLE
WD4 AT T,2'.AND 2!§" DEPTHS
UTiUTY
TUNNEL
SCALE;
100'
Figure 4.1.6 Location of soil sample sites for radium analysis at School A,
A-7
-------
—¥1
o 3 o
LOCATION OF
SUCTION pi. ,
TEST PT,
T
Y«r
lb
UTILITY
Tunnel
SCALE: N — 100'
Figure 4,1.7 Location of suction and test points' used in subslsb communica-
tion tests in School A.
A-8
-------
513 940 1495 1 ^6 546
Figure 4.1.8 Sufcslab radon concentrations measured in November
1989 in School A, pCi/L.
A-9
-------
0 600 1000 1500 2000
SUBSUB RADON NOV 89 (pCi/L)
Figure 4,1.9 Comparison of room radon levels with levels under the slab in
School A,
A-10
-------
LOCATION OF
SUCTION PT,
TEST PT,
-5P# Active
utility
TUNNEL
SCALE:
100'
Figure 4.1.10 Subslab pressure field treasured from SP#1 In School A.
A-™ 11
-------
-+0.003
LOCATION OF;
SUCTION FT. -
TEST PI.
2
SuCtforv
Pressures
Measure
2 Pressures
^SPjf
T
N.
40.oo3t,\
+ 0.001 F->
0.000 J
+0.0041
+ Q.QQ3 l£_
+ 0.00 2_
HSI
UTILITY
TUNNEL
SCALE:
1 00*
Figure 4.1.11 Subalab pressure field measured from SF#2 tn School A.
A-12
-------
0.000 "1 ¦»
-0,00! P-,
-0.002J
+ 0.002
-2,0"WC
LOCATION Of:
SUCTiON PT.
TEST PT,
utiunr
tunnel
SCALE:
100'
Figure 4.1,12 Subs lab pressure field measured from SF#3 in School A,
A-13
-------
-0.003*1 ,
-0.003 L4
-0.004 J\
-0.006
-0.008
-0.013
-0.001
-0,003
-0.00.
a)V
+O.DOV
0.000
0.000.
o.ooo-l v°
3
0,000
O.OOOJ
LJ
r-o.iO"wc
-0.20
-0.30
*0.00)
-0.001
-0.001
4r°'Doo W
o.ooo ¦
Lo.coo 1
LOCATION OF;
SUCTION PT. •
TEST PT.
SP#
Suction
Frtsaayroa
U»a«ur«d
^Pressure#
^SP| Actlv#
N
3
J£
3H
UTILITY
TUNNEL
SCALE: h
100''
Figure 4,1.13 Subslab pressure field measured from SF#4 in School A.
A-14
-------
LOCATION OF:
SUCTION PT.
TEST PT.
+3,002
2.0"WC
4,0
6.0
UTILITY
TUNNEL
SCALE:
100'
Figure 4.1.14 Subslab pressure field measured from SP #5 in
School A,
A-15
-------
Figure 4,1,15 Approximate pressure field extension measured from suction
points 1 through 5 in School A.
A-16
-------
Figure 4.1.16 Suggested ASD mitigation system, school A.
A-17
-------
TO FAN
Figure 4.1.17 Subslab suction point details.
-------
TYPICAL DETAIL OF UNUSED HOT WATER
HEATING PIPES IN THE SLABS OF MOST ROOMS
SCALE; H-IGQ'-H
Figure 4.2.1 Floor plan showing additions, room numbers and
subslab details at School B.
A-19
-------
4.6
6.7
5.0
2,2l 5.7 I
3P
4.8
18.7
N
io.g
T?
1.3
SCALE: K- 100' -H
Figure 4,2.2 Results of June 1989 follow-up CC measurements,
school B, pCi/L.
A-20
-------
35
34
33
39
38
37
32
y 11 l 40| 15l 1l\ 19 I20I2V-
29
30
14
16 18 21
—*-r*
"^42
22
25
25
36
28
27
SCALE: 1—100' —i'
Figure 4.2.3 Location of caniscer numbers foe CC measurements in School B.
A-21
-------
SCALE: k- 100'
Figure 4.2.4 Results of October 1989 CC measurements in
School B, pCi/L.
A-22
-------
SCALE: H- 100'
Figure 4,2.5 Location of soli sample sites for radium analysis at School B.
A-23
-------
LOCATION OF;
SUCTION PT. - •
TEST PT. - o
-Q.
SCALE: H- 100'
'igure 4,2,6 Location of suction and teat points used In sub3lab
communication tests at School 1,
A-24
-------
LOCATION OF;
SUCTION PT. - •
TEST PT. - o
1788
,aoi
as#
1b#2 11^«!
N
SCALE: H*~ 100* -H
Figure 4.2,7 Subslab radon concentrations measured in November
1989 at School B, pci/L.
A-25
-------
600 1000 1500 2000
SUBSUUB BAD ON NOT B9 (pCi /L)
Comparison of room radon levels with levels under the slab in
School B.
0
Figure 4.2.8
A-26
-------
-UNI, (J-4414
LOCATION OF; jfSUCTlON
SUCTION FT. - ^PRESSURES
-«t « ^ JlMEASURED
,EST PT, - °—ljPRESSURES
hi*: «
SCALE*, K-100'
Figure 4,2.9 Subs lab pressure field measured from SP#1 In School 1,
k-27
-------
SCALE: h*- 100' -*H
Figure 4.2.10 Subslab pressure field measured from SP#2 in School B.
A-28
-------
r
LOCATION OF: _3[SUCT10N
SUCTION PT. => if' [PRESSURES
tcct pt „ J^easured
TEST PT. - a—-j pR£SSyRES
L
SP# ACTIVE
7TT¥
ilriyEp
-0.001 -O.B07 -0.013
®^js
L-&01
?
SCALE; K- 1 00' -H
Figure 4.2,11 Subslab pressure field measured from SF#3 In School B,
A-29
-------
SCALE: K- 100' -H
Figure 4.2.12 Subslab pressure field measured from $P#4 in School B.
A—30
-------
SCALE: 1— 1 00' -H
Figure 4.2.13 Subslab pressure field measured from SF#5 in School B.
A—31
-------
SO' RADIUS
SCALE: b*~ 1 00' -M
Figure 4,2,14 Approximate pressure field extension measured from SP#s 1-5 in
School B.
A-3 2
-------
SCALE: K- 1 00' -H
Figure 4.2,15 Suggested mitigation System A for School B,
A—3 3
-------
Boiler Room
G1 G2
B
G3 G4
B
G5 G6
B
G7 G8
B
G9 G10
B
G11 G12
B
G13 G14
B
G15 G16
B
>
i
LO
it'
n
STORAGE
Crawl
Space
Crawl Space
N
B
G21
G20
G19
G18
G17
RECREATION
ROOM
Scale: 20' H
Figure 4.3.1 Basement floor plan and room numbers in School C
-------
Boiler
Room
70.8 6.5 0.7 3.2 2.6 1.4 1.5 3.9
(48.6) (7.7) (1.9) (5.0) (3.2) (3.5) (6.4) (8.9)
Averages
41.6 pCI/L
(26.8)
14.1 5.4 3.2 5.3 4.8 2.3 31.8 4B0.2
(9.3) (7.2) (6.9) (0.8) (2.0) (1.3) (<0.5) (124.5)
Hallway — 2.0
Crawl
Space
Crawl Space
T
N
14.2 35.2
(11.2) (75.4)
176.2 8.9
(189.3) (21.7)
RECREATION
ROOM
Scale: 20' *\
Figure 4.3.2 Results of two-day CC measurements over the periods
3/28-30/90 and 4/10-12/90 in School C, pCi/L.
-------
Boiler Room
+.001"
+.001"
+.001"
-.003"
-.005"
-.009"
+.oo r
.000"
.000"
Fcr
Fb
Fe
>
I
u>
ON
Crawl Space
Fa
Ff
Fd
T
N
-1"
-2"
—4"
RECREATION
ROOM
-.023"
-.037"
-.062"
Scale: 20'H
+.001"
+.001"
+.001"
Figure 4.3.3
Subslab communication test locations and results measured on
11/3/89 in School C.
-------
Boiler Room
1701
1424
1454
Fcr
LI
CI
IE
Fe
>
I
iji
Crawl Space
Fa
Ff
Fd
900
N
RECREATION
ROOM
Scale: 20'H
239
Figure 4.3.4 Subslab radon levels measured on 11/3/89 in School C, pCi/L.
-------
N
Boiler Room
OUTER LIMIT OF
PRESSURE FIELD FROM Fa
-O.OOVWC AT 30'
RECREATION
ROOM
Scale. 1^. 20' *|
Figure 4.3.5 Estimated pressure field extension from suction point Fa in
School C.
-------
>
I
u>
V0
N
RECREATION
ROOM
Scale: 20* H
Figure 4.3.6
Estimated pressure field coverage with proposed mitigation
system in School C.
-------
Figure 4.3.7 Proposed mitigation system for School C.
-------
t £. D J1 i
tarrr
5.4
UTILITY TUNNEL
L""TT"1—el r
I f i-l Li Mt
4.8
2.9
1.3
4.1
7.2
6.0
5.6
3.2
6.2
6.9
4.5
f1
Set 1: March 11-13, 19®
Set 2: tovanfcer 17-20, 1989
4.1
10.0
pnia?
°r -n— , ¦
lOiili
Figure 5.1.1 Pre-nitigation radon levels in School D, pCi/L.
A-41
-------
Total weekdays = 4,0 days and average radon = 2.1 pCi/L
Total weeknights = 4.0 days and average radon = 4.4 pCi/L
Total period = 14.1 days arid radon = 4.1 pCi/L
139 142 145 148 151 154
Day
Figure 5.1.2 CRM results for School D.
A-42
1989 Julian
Continuous radon monitor hourly output in pCi/L
Weeknights
Weekdays
-------
Figure 5.1.3 Radon levels with ASD and tunnel depressurization
systems in operation in School D, pci/L.
A-4 3
-------
Figure 5.1,4 HVAC on, exhaust fans on,ASD off, School D.
A-44
-------
30
20
10
Tunnel depressurization fan on Wednesday noon to Saturday noon
Total period = 22,2 days, average radon = 3,6 pCi/L
Fan on 8.3 days, average radon = 1.2 pCi/L
Fan off 14.0 days, average radon = 5.1 pCi/L
Radon monitor in classroom 27 adjacent to utility tunnel
0
270 275
Wednesday 9/27/B9
280
285
290
295
1989 Julian Day
continuous radon monitor hourly output in pCi/L
utility tunnel depressurization fan off
Figure 5.1.5 CRM results in School D with utility tunnel
depressurization fan on and off (9/27-10/11/89),
A—45
-------
12
\
b
o
"O
KJ
cr
s -
Total Period = 15.1 days and average radon = 2.8 pCi/L
Weekday period = 3.1 days and average radon = 2.1 pC'/L
Weekright period = 6.0 days and average radon = 2.0 pCi/L
0
138
Thursday 5/19/89
142
146
150
1989 Julian Day
Continuous radon monitor hourly output in pCi/L
Weekday periods when class is in session
Weekday periods when class is not in session
154
Figure 5.2.1 CRM results for School E,
A-46
-------
357 363 369 375
1988 Julian Day
Crawl space radon
Classroom radon
Figure 5,2.2 Crawl space depressurization in School E with fan
on and off (12/22/88-1/7/89).
A-47
-------
Upper number = initial radon lest (pCi/L) before mitigation
Lower number = radon test (pCtfL) after overhead ducts installed, subslab ducts sealed, and ASD
installed in pods A and C
Figure 5.3.1 Floor plan of School F with radon levels.
-------
t
20
Q.
~o
o
CL
O
~o
05
cc
0
CT>
cd
CD
>
<
15 -
10
Pod A
Pod B
Pod C
Pod D
Radon Test Number
Test #1, Charcoal test, 2/21/88-2/23/88, no mitigation
Test #2, Charcoal test, date unknown, no mitigation
Test #3, Charcoal test, 12/8/89-12/11/89, seal ducts in pods A & C
Test #4, Electret Test, 2/2/90-2/9/90, ASD fan on in pod C
Test #5, Electret test, 5/11/90-5/18/90, ASD fan on in pods A "and C
Figure 5.3.2 School F radon levels in pods.
A-49
-------
METER
ROOM
10.6
ELEVATOR/
STORAGE
50.1
MECH.
ROOM
8.6
BOILER
ROOM
7.2
STAIRWELL/
STORAGE
MS.
52.3
57.1
OFFICE «3
43.6
FALLOUT SHELTER
OFFICE #4
39.8
CORRIDOR
53,6
43.4
OFFICE
*2
45.6
OFFICE
•1
405
49.9
CRAWL
SPACE
*4.0
Figure 6.1 School G basement area pre-mitigation radon
measurements using activated charcoal canisters.
Monitoring period (10/7 - 9/89). School unoccupied.
A-50
-------
MECH.
ROOM
12.9
ELEVATOR/
STORAGE
30.5
BOILER
ROOM
6.2
STAIRWELli
STORAGE
28.7
44.6
45.5
FALLOUT SHELTER
OFFICE
#2
27.9
OFFICE
#1
29.2
OFFICE »3
23 &
OFFICE «4
30.2
29.5
CORRIDOR
34 2
42,0
CBAWL
SPACE
36.4
Figure 6.2 School G basement area pre-mitigation radon
measurements using activated charcoal canisters.
Monitoring period (12/8 - 10/89). School occupied.
A-51
-------
elevator;
STORAGE
27 3
OFFICE OFFICE
*2 #|
30.9 32.1
OFFICE #3
32 £
OFFICE *4
307
STAIRWELL/
STORAGE
34.3
CORRIDOR
50.8
School G basement area pre-mitigation radon
measurements using activated charcoal canisters.
Monitoring period (12/11 - 13/89). School
unoccupied.
A-52
-------
X 1000 pCM.
X1200 pCL'L
1450 pCi/L X
1260 pCi/L x
X 550 pCi/L
130C pCi/L X
550 pCi/L 4Q0 pCi/L v
x ^ X 1250 pCi/L
X 800 cCt/L
X
1100 pCi/L
X
900 pCW.
X
8QO pCi/L
X 1400 pCi/L
1650 pCi/L X
1100pCI/LX
Figure 6.4 School G basement area subslab radon levels,
A-53
-------
XFO
X FN
XFM
XFK
XFH
XFJ
XFG
XFL
XFI
XFF
XFE
XFD
XFC
XFB
X FA - SUCTION POINT
Figure 6.5
School G basement area subslab communication
testing locations.
A-54
-------
PS
P4
X
P2'
P1
EXHAUST TO ROOF
School G basement subslab depressurization system
layout.
A-55
-------
50
m -
Ui
u
I
©
a
<
a
30
AVERAGE CONCENTRAT ION: 34.2 pCi/L
20
12/14/99
12/17? 89
12/20/89 12/23/89
DATE (MM/DD/YY)
12/26/89
12/29/89
Figure 6.7
School G office CRM pre-mitigation radon
concentrations. Monitoring period: 12/14 - 28/89.
A-56
-------
30
!
p
<
25
20
LU 15
O
X
0
u
1 10 H
5"
PASSIVE MODE AVERAGE; 21 pCi/L
ACTIVE MODE AVERAGE: 11.2 pCi/L
1 1 I 1 1 I " I """" I " T" 1 I ¦ ' I ' ' I ' ¦ I ¦
1/26/90 1/29/90 2/1/90 2/4/90 2/7/90 2/10/90 213/90 2/16/90 2/19/90 2/22/90 2/25/90
DATE (MM/DD/VY)
Figure 6.8 School G office CRM post-mitigation radon
concentrations. Monitoring period: 1/26 - 2/2 3/90,
A-57
-------
METER
ROOM
5 2
MECH,
ROOM
3.7
ELEVATOR/
STORAGE
17.3
BOILER
ROOM
1.7
STAIRWELL/
STORAGE
8.3
8-3
FALLOUT SHELTER
OFFICE
*2
6 2
OFFICE
*1
5.9
OFFICE *3
7.7
OFFICE «4
7.6
CORRIDOR
14 9
9.0
CRAWL
SPACE
S 5
Figure 6.9 School G basement area post-mitigation radon
measurements using activated charcoal canisters.
Monitoring period 2/12 - 14/90.
A-58
-------
500 750 1000
DISTANCE FROM SUCTION POINT (cm)
1500
Figure 6.10 Subslab pressures at distances with respect to
penetration point 1, with and without suction pits
in School G.
A-59
-------
-3
¦ ALL VALVES OPEN. NO SUCTION PUS
m ALL VALVES OPEN, SUCTION PITS AT ALL PIPES
13 VALVES ADJUSTED. SUCTION PITS AT ALL POINTS
P3
SUCTION POINT
Figure 6.11 Comparison of pipe pressures in School G.
A-60
-------
METER
ROOM
3.2
MECH
ROOM
2.1
ELEVATOR
STORAGE
8.0
BOILER
ROOM
1.2
STAIRWELL/
STORAGE
6.6
5 4
OFFICE OFFICE
*2 »1
55 55
5.5
FALLOUT SHELTER
OFFICE S3
5 7
OFFICE #4
5.6
CORRIDOR
7.4
6 3
CRAWL
SPACE
2.6
Figure 6,12 School G basement area radon measurements using
activated charcoal canisters. Monitoring period
3/13 - 15/90.
A-61
-------
DATE (mm/dd/yy)
Figure 6.13 School G basement office post-mitigation radon
concentrations. Monitoring period: 3/2 - 30/90.
A-62
-------
*¦1
0
m
*
g
<
K
o
u
<
OS
6/ 14T9Q 6/13*90 6/24/90 6/29/90
DATE (mmidd/yy)
7/4/90
719/90
7/14/90
Figure 6.14
School G basement office radon concentrations with
ASD system operating and outdoor air dampers for
basement unit ventilator open.
A-6 3
-------
HOUR OF THE DAY
Figure 6.15 School G basement office radon concentrations with
ASD system operating and outdoor air dampers for
basement unit ventilator opened and closed.
A-64
-------
>
I
Cfl
(Jl
UDOU'011
1963
ADDITION
1962
K.RMl ADDITION
Figure 7.1.1 Floor plan showing additions at School H.
ADOIT!oh
-------
-------
•3*
\
Fl£ure
"e63'
,ute««'
nW"
»bets
tot
aeco1
-------
US*S
1 198'« -rpt MS
M|11**S£ fV»**
mK: n«^»f.it «nMS
fcAHGt
1.H*1
^igute
a989 Pre
, febtu^, u pCi/^-
7.V> IfScbooV^. P
ti°"
CG ®casUre
me^ts
-------
— n
MUSIC JL.
ROOM U
r
17.0 •
rr
GIRLS*
GYMNASIUM
IK. ROOM
*
¦
a» y i
»
Figure 7.1.5 Follow-up CC measurements In March 1989 following scaling oE
entry holes by School H staff, pCl/L.
-------
Pre-mitigation CC and (E-perm) measurements in June 1989 on
first floor of School H, pCi/L.
-------
-------
FEBRUARY CC VALUES, pO/L
Figure 7,1,8 Comparison of June 1989 CC measurement to the values measured Is
February 1989 at School H.
A-72
-------
0^^
\ U-
py&KhCt 230®
bahge 400-5700
yljilfe
7.t-9
« J'*"1 *'
sub*
slab t»dotl
¦^gvels
raeasU
xeA
june
1989
-------
J 150
\
•N
0
&
0
J
s 100
Hi
J
0
50
0
0
t o
2 -
~
~
~
-
*
#
~
A
*
*
0
A*
X ^
X ^
H
0
X
B
A
X
B
•
.
X
~
B
B
1
X
a
*
*
¦ a
a ° a
3b
a
H «
B B
100
1000
JUNE SUBSLAB RADON LEVELS, pCi/L
s June Pre—Mit # Feb Screening
A FebFollow-Up x March After Sealing
10000
Figure 7.1.10 Comparison of room radon levels with levels under
the slab at School H.
A—7 4
-------
>
I
-j
ui
Figure 7.1.11 Location of pre-mitigation subslab pressure field extension
suction and test points at School H.
-------
0
a
0.1
0.01
0.001
0.0001
¦ Dpo=2 in.w.g.
~ Dpo~4iiLw.g.
A Dpo=6ia.w.g.
x Dpo=8iiLw.g.
SI
¦ ¦
¦
t
¦
i
~
~
20 40 60 80 100
DISTANCE FROM SUCTION POINT (Ft)
120
140
Figure 7.1.12
Pre-mitigation pressure field extension in the North wing of
School H, June 1989, Suction point in Closet of Room 104.
A-76
-------
0.1
¦ Dpo-2la.w,|.
* Dpos=4ia.w.g.
A Dpo-6iiLW,f.
x Dpo-8 in.w,g.
$
&
0
X
«N
a
a
0,01
ttOGl
A
I
~
1
0,0001
20
40 m 80
DISTANCE FROM SUCTION POINT (Ft)
100
120
Figure 7.1.13
Pre-mirigacjon pressure field extension in the South wing of
School H, June 1989, Suction point in Office of loom 121.
A-77
-------
0
p.
9 0.01
*«
fk
Q
0.001
0,0001
¦ Dpo«2in.w.g.
« Dpo«=4iiLw.g.
4 Dpo=6 in.w.g.
x Dpo-SiiLw.g.
~
A
10 20 30 40
IMOTAMrtJ nJAli gfl/ 'IHAM DATMT /T#\
IaaTnVmmi f l\WM &CrV-fXJv/P'i t X CJ
50
60
Figure 7.1.14
Pre-oitlgation pressure'field extension in the Basement of
School H, June 1989'. Suction point in Art Room.
A-78
-------
f
. tiQn s«kslato P*e
*c-
ssMte
-------
Figure 7.1.15 Continuous radon levels measured in several rooms
of School H.
A-80
-------
r
" n
School H in June 1989 with temporary ASD systems
operating.
-------
Figure 7.1.18 Post-mitigation continuous radon monitor levels
with temporary ASD systems operating in June 1989
at School H.
-------
CO
U>
Figure 7.1.19 pressure field extensions using
temporary ASD systems in June 1989 at School H.
-------
0.1
0
&
0
\
tk
0
o.oi
0.001
b Dpo=l.S iiLW.g. SSD Fan in Rm 120
# Dpo=1.9 inw.g. SSD Fan in Rm 104
~
B ^
~
B
1
~
B
a
e
e
i --
i
m «
¦ * *
i i i
20 40 60 80 100
DISTANCE FROM SUCTION POINT (Ft)
120
Figure 7,1,20 Pressure field extension using the temporary
mitigation systems at School H.
140
A-84
-------
a Dpo==1.75 iaw.g. SSD Fan in Rm 120
« Dpo=1.91 in.w.g. SSD Fan in Rm 104
A Dpo=1.03 in.w.g. SSD Fan in Art Rm
$ «
01
0
~
0.01
0.001
a
4
#
¦
* *
0
20 40 60 SO 100
DISTANCE FROM SUCTION POINT (Ft)
120
140
Figure 7.1.21 Pressure field extension using the permanent
mitigation systems in School H.
A—85
-------
point
r
J02|n04( "" " 10
-.20 „ IU371 -.27
-•"Km l
192 cf»
-.39
ToBl
-.006 fl-.007
,EL32ta:
- \.v*
»•' IT 1
JA ol H «sing
\VW^ s _ m sc^o01
J* . cxtensi01^ 89.
Tiq«re per#»ne
-------
-------
0.6 Vss4
\_U-—\
t.-rt •¦•'! "I '.'I
. \qB9
1-—rssrstf-1"
7 1.24 . floor °^. pCl/L'
iys«*'°perat'
-------
*. 1969 on
«ts in Auq^anent
cc V pe
, 25
-------
>
I
to
o
Figure -asur^ts in Decenber 1,8,
-------
>
I
\o
Figure 7.1.27 Post-raltlgaclon CC measurement results for January 1990 at
School H, pCl/L.
-------
Figure 7.2.1 Floor plan of School I showing additions and dates.
-------
Figure 7.2.2 Location of class rooms and measurement numbers for School I.
-------
Figure 7.2.3 February 1989 pre-mitigation (and follow-up) CC measurements at
School I.
-------
Figure 7.2.k June 1989 pre-mitigation CC measurements at School I.
-------
Figure 7.2.5 July 1989 pre-mitigation CC measurements at School I.
-------
60
J 50
\
»«
u
tk
m
J
II
>
H
J
z
40
30
20
10
1
V
/
<;
/
\
/
\
/
s
Off m Tl Aud 101
V
/
V
1
102 103 104
Room Tested
1 1 Initial Screening Feb.1989 IS Follow Up Feb. 1989
¦ Pre—Mit. June 1989 [3 Pre-Mi t. July 1989
/
S
105 106 107 109 110
Figure 7.2.6 Summary of pre-micigacion radon levels measured In School I by
room number, part. 1.
A-9?
-------
120
J 100
N
u
a
eo
60
>
L]
J
2
0 40
Q
tt 20
<
L
I gsl
<
\
111 112 113 114 115 116 117 11$ 119 120 121 122 123
Room Tested
I I Initial Screening Feb. 1989 25 Follow Up Feb. 1989
3 Pre-Mit. July 1989
I Pre-Mit. June 1989
Figure 7.2.7 Summary of pre-mitigation radon levels measured in School I by
room number, part 2.
h-9B
-------
Figure 7.2.8 Pre-mitigation subslab radon levels measured in
School I in June 1989, pCi/L.
-------
NC - No Communication
o-.CXM*
i-H rH
ooS ¦
• •
1 1
-.005
-.009
O
|
+.001 to
-.001®
L_sL 1
Measured at 6.5" WC
Measured at 6" WC
I L
~'°§2
' • 1
-.018 !
°
.-.000
o
as j" *
-
o
-.001
-.001 to
o
-.002
1
1 1
1
Measured at 5" WC
Figure 7.2.9 Pre-mitigation subslab pressure field extension
suction and test point locations at School I.
-------
1 *
0.1
0.01
0.001
0.0001
~
s
+
a Dpo*=4 in.w.g.
* Dpo=5 iaw.g,
A Dpo=6i0.w.g.
k Dpo=6.5 in wg
+ Dpo»=8 in.w.g.
A
+
+
10 20 30 40
DISTANCE FROM SUCTION POINT (Ft)
50
60
Figure 7.2.10 Pre-mitigation pressure field extensions In School I In June
1939.
A-101
-------
I
N
Figure 7.2.11 Initial mitigation system design layout for School I.
-------
70
60
J
0 50
&
*
J
[H 40
)
Pi
^ 30
1
0
Q 20
10
0
Post-Mitigation Avg.« 2.46 pCi/L
.i.TroytttmS
ii ii
07/31/89
08/01/89
08/02/89
DA'l'b
08/03/89
08/04/89
Figure 7.2.12 Continuous radon levels in Room 120 of School I.
A-103
-------
Figure 7.2.13 Post-mitigation pressure field extensions in
School I using the ASD mitigation systems.
-------
Figure 7.2.14 Post-mitigation CC measurements in School I in
August 1989 with ASD systems operating, pCi/L.
-------
120
n 100
80
60
40
20
0
H
¦Fin
JUL
O TL 101 103 105 107 110 112 114 116 11$ 120 122
WR A 102 104 106 109 111 113 115 117 119 121 123
Room Tested
Pre-Mit. July 1989
Post-Mit. Aug. 1989
Figure 7.2.15 Summary of pre-mitigation (July 1989) and post-mitigation (Aug.
1989) radon levels in School I.
A-106
-------
o
-J
a
r
1.4
2.0
i
1.5
2.5
|
r ff
l
.. 3
±LJ 24
l a
»]_jT^T^]5
I
N
4.6
3.0
h=J
i
Figure 7.2.16 Post-mitigation CC measurements in School I in December 1989,
pCi/L.
-------
Figure 7.2.17 Post-mitigation CC measurements in School I in January 1990,
pCi/L.
-------
6" LINE
Figure 7.2.18 Final mitigation system configuration at School I.
-------
If
3.5
6=
*
2.5
U 3.4
f FT-i
H
¦ 3
J 0.!
*~IL
M
1
1]
II Jt
3.0
1.2
3J
1.7
3
0.6
t
N
1.2
T—r
1.8
i r -
1.3
1.6
Figure 7.2.19 Post-mitigation CC measurement results for School I in February
1990, pCi/L.
-------
Figure 7.3.1 Floor plan showing additions and subslab details in
School J.
A-lll
-------
27-
17
T1
18
T1
OJ
T-*
20
T1
U
16
L. c
li
15
--L
11.
14
L.
Li
13
22 24
iid^i
21 h
BOILER
* room
KfTCMEN
STABE
26
23
5YR25]
CRAWL SPAC£
7
8
C.T.
1
—I" B~
1 1
10
lower level
Figure 7.3.2 Location of canister numbers for CC measurements
in School J.
A-112
-------
Figure 7.3.3 Results of February 1989 CC screening
(and follow-up) measurements in School J, pCi/L.
A-113
-------
Figure 7 3 4 Results of July 1989 CC measurements in School J,
pCi/L
A** 114
-------
100
t! 80
60
Ol
4) 40
J
D 20
(July)=0.27*Rji(Feb)
20
40 60
FEB 1989 DATA (pCi/L)
SO
100
Figure 7.3.5 Comparison of February and July 1989 CC
measurements in School J.
A-115
-------
1
o
0
o
o
f
71
T1
n
T1
i:
o
N
U
11
• ll
tl
o
1, .. . _
o
E
o
L
o
111 L
location OFj
SUCTION pr.
test pr.
c*u«i space
-------
LOCATION OF;
SUCtiON PT. - '
TEST PT. -
1 203
'2SS
341
SM
f
o
o
Q
T m
T1
T1
11
1! O ' »
N | 11
11.
• 11
Li
°
o
o
0
1 1*2
L
138
u C
76
' ' L
a*
* • L
SOW-*
ROOM
on
CKAWL SPACE
ttS?"
i as
O
23i
O
B.T.
170
o
' S28
o!T
9
-------
90
a80
J
g 70
&
v 60
.1
0 50
0
1 40
30
20
10
0
~
(Room)=4.8+0.03*Rn(SS), R~ 2=0.32
200 300 400 500 600 700
SUBSLAB RADON JUNE 89 (pCi/L)
B JULY 89 DATA # FEB 89 DATA
900
Figure 7.3.8 comparisons of" February and July"" 1989 room
radon data to subslab in June 1989 in School J
A-118
-------
Figure 7.3.9 subslab pressure fields measured in June 1989,
School J
A-119
-------
Figure 7,3.10 Proposed mitigation system for School J.
A-120
-------
N
Figure 7.3.11 Additional detail for North-South mitigation system
including basement rooms of School J.
-------
PVC TOILET
FUNOE
TKEATEO PLYWOOD
FAN EXHAUST
OVER ROOT
AWAY FROM
AHT INTAKES
ROW SUB
4" OWUETCR PVC PIPE
TO OTHER
SUCTION POINTS
(IF NEEDED)
-IT
HOPE UCURRANC
FAN UOVMTED
AT OR NEAR
ItOOF LEVfU
DOT TMROUOH
BLOCK VfHT
OR WALL HOUE
Figure 7.3.12 Typical sub-membrane depressurizatlon system for crawl spaces,
A-122
-------
Figure 7.4.1 Floor plan showing additions and dates of School K.
-------
>
I
M
M
OFFICE
CLINIC
9
a e]
TL
10
Hi el
8
ta fa
3 G
4
sHS
EQUIP
~
LIBRARY
OFFICE
LIBRARY
~
y OFFICE
WORK
ROOM
11
13
N
m
15
17
IL._.
19
'1'
21
23
it
51
a
Ho...
S
15
L AUDITORIUM
JcAFETERIUM
KITCHEN
[C
12
Is
14
L
16 e
E
18
t
k
lii
Is
20
22
24
SCALE h—50"—H
Figure 7.4,2 Location of room numbers in School K.
-------
©
>
I
w
NJ
Ul
a s
©
b-£
©
©
©
Ml
icDqcr
a e
©
ta El
cj (i
©
©
sn
0
"n
N
~
©
c ©
"1
1'
©
©
31
©
si
1-
©
a
©
• R
\ ©
r
b
©
U
©
© '
Ic.
©
ic
©
Lb
©
Ic
©
SCALE
Figure 7 . A . 3 Location of canister numbers for CC measurements In School K.
-------
>
I
to
en
28.3
a m
22.6
8-6
11.3
4.0
B-fl
7.3
25
T ,
I
/
-A
21.7
HI E
8.5
tu m
^—El
4.2
17.1
1.2
BHS
3.7
£
1.6
~
N
C 4.4
~
l
9.4
IsL
6.3
EL
CO
3.8
EL
4.2
r
29.9 ^
(15.2)
70.1 U
(35.1)
L
15.9 c
52.0 k
(38.2)
It
l£
It
8.3
11.5
12.3
SCALE
50'
Figure 7.4.4 Results of February 1989 CC measurements (and
follow-up) in School K, pCi/L
-------
>
I
H
to
vj
6.3
ta is]
5.8
3-6
5.7
2.3
O
S-E
2.0
10.1
19.1
la a
12.5
g e
a E
7.9
9.5
6.9
£
11.0
~
N
13.4
rid
22.5
11.7
4.7
T
T
4.9
7.0
el
71
a
r
n
a
lc
^ 10.0
lc
2.4
Lb
1.6
L
2.1 c
lc.
4.1
T
l£
U
lc
0.5
0.9
3.0
SCALE
Figure 7.4.5 Results of July 1989 CC measurements in School K,
pCi/L
-------
80
370
360
0.
v
J 50
I
I"
J
z
Q20
i 10
30
II
liikiki
llli
1
1 3 5 7 9 11 13 15 17 19 21 23 25 27
2 4 6 8 10 12 14 16 18 20 22 24 26 28
CCNUMBER
I I FEB 89 DATA Bj'JL89DATA
Figure 7.4.6 Comparison of February and July 1989 CC
measurements in School K.
A-128
-------
a &
Existing Sub—slob
Suction
System
to
S~£
g 2
a a
ii n
3-S
J1
~
N
S
Test Points =
_Exlst1ng Sub—slab
"Suction System jfZ
a
(
>
¦ ¦
El
it
ft
4i
5]
re
[£
l£
L
C
It
O
r
SCALE
50"
Tt
Figure 7.4.7 Location of suction and test points used in June
1989 communication tests in School K.
-------
-0.011".
Existing Sub—slab
Suction
System #1
II E
B—£
H
u>
o
—4.5"WC
-0.009"
Q
t
U H
a b
a—m
a-i
n
^—0.003"
-0.037"
-0.001"
~
N
tL
Test Points =
0.000"
Existing Sub—slab
Suction System #2
-1.80"WC
<
~
.1
T
il
£1
si
A
h
51
re
~E
0.000
A
0.000"
SCALE
50'
Figure 7.4.8 Subslab pressure fields measurements in June 1989
in School K.
-------
a e
s-d
a e
a B
3 H
Existing Suh^SlaE
Suction
System #1
i
33
o
3-1
H
61
40
~
N
i
Test Points =
Existing Sub—slab
' Suction System #2
39
/
«
-i
(
«—
i
1
4
a
51
51
A
ii
re
l£
u
L
e
tc.
T
SCALE
290
50'
Figure 7.4.9 Subslab radon concentrations measured in June 1989
in School K, pCi/L.
-------
a &
el It
>
I
H*
U>
M
M
U 5
S—13
s-i
a-i
H
/
N
Suction Points = #
Test Points = o
«
o
.
T
Ifi
o
La
•
1*
e
•
•
/
»
e
1-
=i
ii
si
m
«i
re
SCALE
50'
Figure 7.4.10 Location of suction and test points used in July
1989 communication tests in School K.
-------
792
401
a &
b4
41
55
32
19
122-
57-
161
2
g e
a__E
a—e
II
1445
221
-333
50
97
-80
273
313
J
/
N
Suction Points =
Test Points =
,128
213 I155
MTU
501 274
ta el
±
").
/
T
Lc
«
o
lc.
{ 1414
45
220
922
195
375
SCALE
50'
280
Figure 7.4.11 Subslab radon concentrations measured in July 1989
in School K, pCi/L.
-------
g, FEB 89 DATA ^ JULY 89 DATA
Figure 7.4.12 Comparison of February and July 1989 room radon
levels to the subslab levels measured in July 1989
in School K.
A-134
-------
a e
g-i
-0.0W-.,
-0.014" Li-
-o.oi r*.
-2.1
—4.0"
-•.o-
0.000"-! .
-0.001* IJ
-0.001'J ^
0.000-1
0.000"
0.000" J
olooo1
0.000".
~ E
a e
~
N
I
Suction Points
Test Points
EL
EL
Suction
Point #
ij Suction
0 [—Pressures
Measured
i l_Pressures
^— SP Active
EL
ElL
EL
JH
Ifi
o
La
o
1*
e
O
it
o
t
SCALE
50'
Figure 7.4.13 Subslab pressure field measured from suction point 1
in School K.
-------
2 la
1=6
Moor-i
0.000* }*—
wwJ
3—IS
a iz
ro.oofir
M ouwo"
o*""" Loam-
pr-6.004"
J -0007"
a—m
3-f
H
/
N
EL
Suction Points
Test Points
Suction
Point #
2J Suction
0 1 Pressures
= Q
\l Measured
21 Pressures
SP Active
EL
EL
r j~i
sL
0
0
.
T
l£
•
u
0
Is
c
0
Ifc
0
It
La
SCALE
50*
Figure 7.4.14 Subslab pressure field measured from suction point 2
in School K.
-------
a e
til E
Ei—B
3-6
JL
OWI
-------
a e
ta a
3 G
fHi
H
/
N
I
EL
Suction
Point §
Suction Points
4J- Su
= tM_Pr.
ction
Pressures
Test Points = Q
\ I Measured
4 LPressures
L
SP Active
(LOOft" IX. I
tsL
SL
~ta E ® E
J-\ 1/--4-
OpOOfl—iA -Mori, 0 \ rn.rw
AJO0- pJ -t*or (""i -4.®- sjooo-
6400- J HLAtrJ L-ctf" L0.000-
"13
SCALE
50'
Figure 7.4.16 Subslab pressure field measured from suction point 4
in School K.
-------
>
I
H
CJ
VD
25 Ft Radius
~
N
30 Ft Radius
25 Ft Radius
m
Suction Points = %
Test Points = o
20 Ft Radius
o
o .
a. 1
T
T
51
ol
«1
r
n
si
fc
SCALE
50'
Figure 7.4.17 Summary of subslab pressure field extensions in School K.
-------
T4 FAN #1
>
I
O
II H'
b-£
a
M1
6" PVC
3 E
a eJ
¦ 4" PVC
H-i
II
/
N
4" PVC
m
T4 FAN #2
6" PVC
SCALE
50'
MAKE SURE THIS
ROOM NOT OVER
CRAWL SPACE
Figure 7.4.18 Proposed mitigation system for School K.
-------
N
v
T
i r
"1
T
T
*-
L
L
L
1962
ADDITION
ORIGINAL BUILDING 1959
T ¦¦
_[
T T
_n i.
1962
ADDITION
SCALE: h— 50' —H
Figure 7.5.1 Floor plan showing additions and dates of School L.
-------
N
V
SCALE: H— 50" —H
Figure 7.5.2 Locations and extents of the utility tunnel in School L.
-------
N
V
CLASSROOM NUMBERS
CC MEASUREMENT NUMBERS Q)
SCALE: H—50'—H
Figure 7.5.3 Locations of room and canister numbers used in CC
measurements in School L.
-------
N
V
L
J
L
L
j
4.3
2.9
8.3
1.5
2.9
r
T
r
r
T
>
I
24.3
38.8
40.3
n
-(35.8)
-,(31-5)
23.0
32.1
T
T
I
I
3
38.0 L
11.3 L
13.5 L
13.1 L
7.7 L
17.6
(4.9)
L
0.8
r
J
5.7
n
L
1.9
r
J
7.9
T
L
11.3
r
-rn' t\
17.9 17.1 | 5.1 \
10.3
SCALE: H—50"—H
Figure 7.5.4
Results of February 1989 and follow-up CC
measurements, School L, pCi/L.
-------
N
V
I
L
J
L-
60.7
56.2
33.7
r
r
L
j
L
J
L
25.3
r
26.9
T
5.5
r
8.9
T
9.2
r
L
L
L
L
L
26.5
17.5
20.0
15.6
18.4
21.4
SCALE: H—50'—H
Figure 7.5.5 Results of June 1989 CC measurements in School L, pCi/L
-------
70
SO
86
o
en
!s
o
40
39
20
10 r
JL
r
~
h
1 2 3 4 8 • t 8 B SO it 12 13 14 16 it 1? 18 19 20 21 22 23 24 28 26
CC NUMBER
FEB 80 DATA
JUNE 89 DATA
Figure 7.5.6 Comparison of February and June 1989 CC
measurements in School L
A—146
-------
N
v
Suction Pts. = @
Teat Pts. = O
>
i
M
-J
1
o
r.
o
o
o
"1
o
T
X
T
o
o
1 L
o
L
o
I
o
o
SCALE: H 50" —H
Figure 7.5.7
Location of suction and test points used in
June/July 1989 communication tests in School L.
-------
N
v
Suction Pts. = ©
Test Pts. = O
234 180 228 480 300
^58 228>jg—-5;
282-
—q—
3
-840
210 126 72 588 510 336
2052 2460 654
1038
630 780
cp
1488 408
-858,
—TJi!
1488 1038 1104 330 210
SCALE: H— 50* H
Figure 7.5.8 Subslab radon concentrations measured in June/July
1989 in School L, pCi/L.
-------
SUBSLAB RADON JUNE 89 (pCi/L),
m FEB 89 DATA + JUNE 89 DATA
Figure 7.5.9 Comparison of February and June 1989 room radon
levels to the subslab levels measured in June/July
1989 in School L.
A-149
-------
10000
x
0 iooo
&
V
>
100
0 W
III
6 1 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
CC NUMBER
FEB 89 ROOM DATA
I JUNE/JULY 89 SUBSLAB DATA
Figure 7.5.10 Caparison by location of the February 1989 room
School l subslab radon levels in
A-1S0
-------
I
10000
2
\
0 1000
%
ft too
[1}
a
z
0
Q 10
6 7 S 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 2$
CCNUMBER
1 I JUNE 89 ROOM DATA
I JUNE/JULY 89 SUBSLAB DATA
Figure 7.5.11 Comparison by location of the June 1989 room and
June/July 1989 subslab radon levels in School L.
a
A-151
-------
>
I
M
U1
M
0.000'
0.000
0.000.
0.000
0.000
0.000 J
Suction Pts. =
Test Pts. =
+0.001"
+0.002
+0.001 Jy
0.000
0.000
-0.002
r
CTHL
L
Suction Pt. #
N
v
Suction
Pressures
Measured
Pressures
71
SP Active
0.000 -
1 1
o o
o o
o o
(0
1
~-2"WC
-0.003
-4" \
9"
—0.004_
-0.013.
-0.003
-0.004
L—0.004
-0.005
-0.007
-0.010
T ¦
_C
-ot4i
1.
fl
L
L
L
¦
o
o f
o
o
o
SCALE: H—50'—H
Figure
7.5.12 Subslab pressure field measured in June
suction point 1 in School L.
1989
from
-------
>
I
»-»
ui
w
r
Suction Pt. §
N
V
Suction Pts. = ®
Test Pts. = 0*tE
+0.002
o.ooo
+0.001 J
2 r Suction
/L Pressures
Measured
Pressures
ttA
-0.008
-0.010
L—0.015
-0.001
-0.002
L—0.004
SCALE: H— 50" H
Figure 7.5.13 Subslab pressure field measured in June 1989
suction point 2 in School L.
from
-------
p Suction Pt. §
N
v
Suction Pts.
Teat Pts.
®
-f
Suction
Pressures
Measured
Pressures
SP Active
-0.006
-0.009
L—0.012
0.000
0.000
-0.001
¦J
0
O
1..
o
o
...r.
o
n
rh
T
o
-r>
o
1 c
o
L
o
¦
o
o
1 1 V
L
\r
J
o
n
L
o
r
o
\ \n
0.004
-0.006
-0.015"
-0.022
-0.033-
-o.ooa
"—0.018
-0.028
_—0.040
SCALE: H— 50< —H
Figure 7.5.14 Subslab
suction
pressure field measured in June 1989 from
point 3 in School L.
-------
Suction Pts.
Teat Pts.
[
cr|t
Suction Pt. §
N
v
Suction
Pressures
Measured
Pressures
SP Active
>
I
M
U1
-------
N
v
SCALE: H— 50" —H
Figure 7.5.16 Summary of June 1989 pressure field extensions in
School L.
-------
N
v
SCALE: H—50"—H
Figure 7.5.17 Proposed mitigation system for School L.
-------
N
V
SCALE: H—50*—H
Figure 7.5.18
Anticipated pressure field coverage using the proposed
mitigation system in School L.
-------
>
I
I-1
U1
*0
1985
ADDITION
(OVER CRAWL SPACE)
1964
ADDITION
(OVER CRAWL SPACE)
SCALE: K50'-H
Figure 7.6.1 Floor plan showing additions and dates of School M.
-------
>
I
I-*
01
o
CLASSROOM NUMBERS
CC MEASUREMENT NUMBERS Q
N
i
111A
JH3
KIT I KIT
I
mmi]
101
1.
©
1 T 1 1
_L 1_
103
¦"
©
\®m
AUD/CAF
BOOKROOM
SCALE: 50' -H
Figure 7.6.2 Locations of room and canister
measurements in School M.
numbers used in CC
-------
i
3.4
5.1
3.6
3.9
3.6,
6.4,
5.8y
>
I
M
10.4
4—n
15.9
FT
6.3
llllllll
J L
22.6
(23.1)
22.2
[11.9)
| ^ i_
9.2
1
"T
1
3
7.8 t¥-
LH^
19.0
9.3
49.0
46.6
.-I
42.6
(32.7)
_ .
J L
54.4
(36.1)
SCALE: h-50' H
. 7 fi 3 Results of February 1989 screening (and follow-up)
Figu - • cc measurements in School M, pCi/L
-------
Figure 7.6.4 Results of July 1989 CC measurements in School M.
-------
i 3 3 4 S • f » B to U 12 13 U IB 18 17 18 IB 2C 21
CC NUMBER
~ FEB Si DATA H JULY 89 DATA
Figure 7.6.5 Comparison of February and July 1989 CC
measurements in School M.
3^
-------
FEBRUARY 1989 DATA (pCi/L)
Figure 7.6.6 Correlation of February and July 1989 CC
measurements in School M.
A—164
-------
SUCTION PTS. - •
TEST PTS, - o
N
i
ni
SCALE: H~ 50' H
Figure 7.6.7 Location of suction and test points used in July
1989 subslab communication tests in School M,
A-165
-------
Figure 7.6.8 Subslab radon concentrations measured in July 1989
in school M, pci/L. 1
A-166
-------
60
A
J 50
N
trf
%
v 40
0 30
20
0
10
0
Feb,Rn(Rm)=13.5+.05*Rii(SS), R~ 2=0.5
~ 0
July Rn(Rm)-8L*+O.Q2*Rn(SS), 2=0.2
0 100 200 300 400 500 600
SUBSLAB RADON JUNE 89 (pCi/L)
H FEB 89 DATA * JULY 89 DATA
700
SCO
900
Figure 7.6.9 Comparison of February and July 1989 room radon
levels to the subslab levels measured in July 1989
in School M.
A-167
-------
SUCTION PTS
TEST PTS.
-0.007*1
-0.014 P-^o
-0.020J ^
-0.028
-0.086
—0.095
SCALE: KSO'-H
Figure 7.6.10 Subalab pressure field measured in
suction point 1 in School M.
A-168
-------
H
uction Ft,
SUCTION PTS,
TEST PTS,
SP Actlvi
0.007
0.013
0,018
038
073
100
0.0001
0.000
0.000.
0.009
0.017
0.023
0.002
0.003
0.004
0.000
-0,002
-0.003
SCALE: H~ 50' H
Figure 7.6.11 Subslab pressure field measured in July 1989 from
suction point 2 in School M.
A-169
-------
Figure 7.6.12 Subslab pressure field measured in July 1989 from
suction point 3 in School M.
A-170
-------
Figure 7.6.13 Subslab pressure_field measured in July 1989 from
suction point 4 in School M.
A-171
-------
SUCTION PTS.
TEST PTS.
-o.oor
-0,001
-0.002J
-0.004"
-0.007
-0.010.
SCALE: h-50'H
0.001
-0,002
.-0,002
2"WC
S"
-10"
0.004
0,007
0,009
j r-o.oo2
- 3 —0.003
L~0,§04
000
000
ooo
0.003
0.062
L-0.085
Figure 7.6.14 Subslab pressure field measured in July 1989 from
suction point 5 in School M.
A-172
-------
Figure 7.6.15 Summary of July 1989 subslab pressure field
extensions in School M.
A-173
-------
Figure 7.6,16 Proposed mitigation system for School K
A-174
-------
4
B
10 20 30
AVERAGE RADON CONCENTRATION (pCi/L)
Figure 8.3.1 Standard deviation as a function of the average
collocated CC measurements.
A-17 5
-------
APPENDIX
TABLES
-------
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
NOV J
(pCi,
1416
298
733
714
918
184
612
401
215
680
755
546
S97
116
1495
567
940
379
513
244
765
490
535
0
101
26
568
0
1495
TABLE 4,1.1. SCHOOL
Room
Usage
DATS SUMMARX
Radon Radon
Level Level
Jun 89 Oct 89
(pCi/L) (pCi/L)
Cafeteria
3.3
4.0
Boiler Room
1.1
Kitchen
4.5
Teachers' Lounge
7.1
Work Room
3.9
4.4
Coach
Office
2.3
Auditorium
5.8
5.1
Office
7.2
11.7
Principal's Office
11.6
Claes
Room
11.7
Class
Room
10.3
7.3
Class
Room
2.0
Claes
Room
2.2
Class
Room
5.6
Class
Room
2-. 7
Class
Room
3.3
Class
Room
10.3
4.0
Class
Room
4.2
Class
Room
3.2
2.9
Library
4.2
3.7
Class
Room
3.3
Class
Room
9.1
Class
Room
4.9
2.6
Clasa
Room
10.2
Class
Room
6.4
Class
Room
4.0
Class
Room
9.6
3.3
Class
Room
3.2
C lass
Room
4.9
Class
Room
00
2.1
Class
Room
6,3
Class
Room
2.5
Class
Room
4.4
12 34
5.95 4.96
2.8 1.1
10.3 11.7
B-2
-------
TABLE 4.2.1, SCHOOL B DATA SUMMARY
Canister Room
Number Usage
(Fig 4.2.3)
Radon
Level
Jun 89
(pci/L)
Radon
Level
Oct 89
{pCi/L)
Sub S1ab
Radon
Nov 89
(PCi/L)
1
Class Room #1
18.5
11.1
232
2
Class Room #2
4.3
979
3
Class Room #3
4.8
393
4
Class Room #4
8.5
2.5
609
5
Class Room #5
14.2
5.4
808
6
Class Room #5
1.6
272
-
Hall Room 6
577
7
Class Room #7
1.2
1.2
267
8
Class Room #8
0.9
188
9
Work Room
3.4
235
-
Hall TRW
552
10
Class Room #2 5
2.7
801
11
Class Room #9
1.8
819
12
Office
4.4
13
Office
4.8
14
Library
13.4
5.0
865
40
Class Room #10
4.7
413
15
Class Room #11
2.2
1.4
575
16
Class Room #12
2.6
802
17
Class Room #13
1.3
561
18
Class Room #14
4.8
1.7
128
19
Class Room #15
5.7
2.7
353
20
Teachers' Lounge
5.5
286
21
Class Room #16
1.2
443
-
PE Office
1321
22
Office 1
18.7
9.0
503
23
Office 2
2.7
.24
Toilet
2.1
-
Hall Room 16
618
25
Class Room #17
10.9
7.8
26
Class Room #18
5.1
605
27
Class Room #19
3.2
28
Cafeteria
2.8
878
29
Auditorium
7.0
1438
30
Kitchen
2.1
31
Health
2.2
32
Class Room #20
1.1
308
33
Gymnasium
6.7
5.8
34
Class Room #21
5.0
3.5
-
Coach's Office
1440
35
Boiler Room
1.1
36
Music Room
1.3
2.6
320
37
Class Room #22
2.2
158
38
Class Room #23
2.4
39
Class Room #24
4.6
5.9
1788
-
R24L Closet
980
-
R24M Closet
182
Number = 14 40 35
Average = 0.26 3.59 620
Minimum = 1.20 0.90 128
Maximum = 18.70 11.10 1788
B-3
-------
Table 6,1. statistical analysis of activated charcoal measurements performed in
basement area of School G
X,i OCTOBER 7-9, 1989
MBfeH: STD, DEV.: STD. ERROR: VARIANCE: COEF. VAR. : COUNT:
39.34 16.55 4.27 273.78 42.06 15
MINIMUM: MAXIMUM; RAKGE: SUM SUM SQUARED; #MISSING
7.2 57.1 49.9 S90.1 27047.41 0
Table 6.2, Frequency distribution of activated charcoal measurements performed in
basement area of School G
X,: October 7-9, 1989
FROM; f>l TO: l<) COUNT: PERCENT:
0
4
0
0%
4
8
1
6.67%
a
12
2
13.33%
12
16
0
0%
16
2D
0
0%
20
24
0
0%
24
28
0
0%
28
32
0
0%
32
36
0
0%
36
40
1
6.67%
40
44
4
26.67%
44
48
2
13.33%
48
52
2
13.33%
52
56
2
13.33%
56
60
1
6.67%
B-4
-------
Table 6.3. Statistical analysis of activated charcoal measurements performed
in basement area of School G
Xt: DECEMBER 8-10, 1989
MEAN: STD ¦ DEV.: STD. ERROR; VARIANCE: CO?!?. VAR. ; COUNT:
30.01 11-03 2.85 121.72 36.77 .15
MINIMUM: MAXIMUM: RANGE: SUM: SUM SPURRED : #MISSING;
6.2 46.5 40.3 450.1 15210.15 0
Table 6.4. Frequency distribution of activated charcoal measurements performed in
basement area of School G
X,: DECEMBER 8-10, 1989
FROM: (>)
V
o
COUNT:
PERCENT'
0
4
0
0%
4
8
1
6.67%
8
12
0
0%
12
16
1
6.67%
16
20
1
6. 67%
20
24
0
0*
24
28
1
6.67%
28
32
6
40%
32
36
1
6.67%
36
40
1
6.67%
40
44
1
6.67%
44
48
2
13.33%
48
52
0
0%
52
56
0
0%
56
60
0
0%
B-5
-------
Table 6.5. Statistical analysis of activated charcoal measurements performed
in basement area of School G
X,s DECEMBER 11-13, 1989
MEAN: STD- DEV.: STD. ERROR; VARIANCE: COEF. VAR.i COUNTS .
35.27 10.06 4.01 112.38 30.05 7
MINIMUM: MAXIMUM: RANGE: SUM: SUM SQUARED: #MISSING
27.3 58.8 31.5 246.9 9382.77 8
Table 6.6. Frequency distribution of activated charcoal measurements performed in
basement area of School G
X,: DECEMBER 11-13, 1989
FROM: f»l
TO:
f<)
COUNT:
PERCENT:
0
4
0
0%
4
8
0
0%
8
12
0
0%
12
16
0
0%
16
20
0
0%
20
24
0
0%
24
28
1
14.29%
28
32
2
28.57%
36
36
3
42.86%
36
40
0
0%
40
44
0
0%
44
48
0
0%
48
52
0
0%
52
56
0
0%
56
60
1
14.29%
B-6
-------
Table 6.7, Results of Subslab Communication Testing in School G
TEST DISTANCE FROM PRESSURE
HOLE SUCTION POINT (ft) DIFFERENCE (ill. H20)
FA
¦ 0
-0.88
FB
1.0
-0.78
FC
2.0
-0.52
FD
2.5
-0,50
FE
4.5
-0.35
FF
6.5
-0.32
FG
11.0
-0.20
FH
16
-0.12
F J
18
-0.05
FJ
21
-0.10
FK
31
-0.03
FL
31
-0.01
FM
35
—0.02
FN
40
-0.00
B-7
-------
Table 6.8. Statistical analysis of hourly pre-mitigation radon concentrations
in Office #4 of School G
X,s DECEMBER 12-28, 1989
MEAN: STD. DEV.: STD. ERROR; VARIANCE; COEF. VAR. : COUNT;
34.24 4.14 0.23 17.17 12.1 334
MINIMUM; MAXIMUM: RANGE; SUM; SUM SQUARED; #MISSING
21.7 45.9 24.2 11436.2 397293.1 1
Table 6.9. Frequency distribution of hourly pre-mitigation radon concentrations in
Office #4 of School G
Xjs DECEMBER 12-28, 1989
FROM; (Z)
V
o
t-l
COUNT;
PERCENT;
0
4
0
0%
4
8
0
0%
8
12
0
0%
12
16
0
0%
16
20
0
0%
20
24
0
.9%
24
28
1
5.99%
28
32
2
22.75%
36
36
3
35.33%
36
40
0
28.14%
40
44
0
5.99 %
44
48
0
.9%
48
52
0
0%
52
55
0
0%
56
60
1
0%
B-8
-------
HERN:
Table 6,10. Statistical analysis of hourly radon concentrations with the
subslab depressurization aystem in the passive mode in School 6
STD. DEV.: STD.
X |: PASSIVE MODE
ERROR; VARIANCE;
COEF. VAR.:
COUNT;
20.96
4.06
.36
16.51
19.38
124
MINIMUM;
MAXIMUM: RANGE;
SUM;
SUM SQUARED:
fMISSINO
12.3
27.3
IS
2599.4
56521.44
Table 6.11. Frequency distribution of hourly concentrations with subslab
depressurization system in the passive mode in School G
X,: PASSIVE MODE
FROM; 1>) TO: (<'1 COUNT: ¦ PERCENT:
0
4
0
0%
4
8
0
0%
B
12
0
0%
12
16
18
14.52%
16
20
34
27.42%
20
24
31
25%
24
28
41
33.06%
28
32
0
0%
32
36
0
0%
36
40
0
0%
40
44
.0
0%
44
48
0
0%
48
52
0
0%
52
56
0
0%
56
60
1
14.29%
B-9
-------
Table 6.12. Statistical analysis of hourly radon concentrations with ASD
system in the active mode in School G
X,: ACTIVE MODE
MEftN: STD . DEV.; SID. ERROR: VARIANCE; CQ5F. VAR. : COUNT:
11.17 2.59 .11 6.69 • 23.15 545
MINIMUM; MAXIMUM: RANGE I SUM: SUM SQUARED: #MISSIHG
5.3 16.7 11.4 6089.6 71683.8 0
Table 6.13, Frequency distribution of hourly radon concentrations with ASD system in
the active mode in School G
Xj; ACTIVE MODE
FROM: l'xs\
TO:
(<)
COUNT:
• PERCENT
0
4
0
0%
4
8
82
15.05%
8
12
207
37.98%
12
16
255
46.79%
16
20
1
. 18%
20
24
0
0%
24
28
0
0%
28
32
0
0%
32
36
0
0%
36
40
0
0%
40
44
0
0%
44
48
0
0%
48
52
0
0%
52
56
0
0%
56
60
0
0%
B-10
-------
Table 6.14. Statistical analysis of post-mitigation activated charcoal
measurements performed in baeement area of School G
XL: FEBRUARY 12-14, 1989
HE AM ! STD . DEV. i STD ¦ ERROR i VARIANCE: COEF. VAR. : COUNT :
8.02 4.17 1.16 17.42 • 52.02 13
MINIMUM: MAXIMUM; RANGE; - SUM: SUM SQUARED: ^MISSING
1.7 17.3 15.6 104.3 1045.85 2
Table 6.15. Frequency distribution of post-mitigation activated charcoal measurements
performed in basement area of School G
X,: FEBRUARY 12-14, 1989
FROM: (>\
~3
O
A
COUNT:
PERCENT:
0
4
2
¦ 15.381
4
8
5
38.46%
8
12
4
30.77%
12
16
1
7.69%
16
20
1
7.69%
20
24
0
0%
24
28
0
0%
28
32
0
0%
32
36
0
0%
36
40
0
0%
40
44
0
0%
44
48
0
0%
48
52
0
0%
52
56
0
0%
56
SO
0
0%
B-11
-------
Table 6.16. statistical analysis of post-mitigation activated charcoal
measurements performed in basement area of School G
X,s MARCH 13-15, 1989
MEAN: STD~ DEV.: STD, ERROR; VARIANCE: CQEF. VAR.; COUNT:
5.04 . 2.01 .54 4.05 39.89 14
MINIMUM: MAXIMUM: RANGE: SUM; SUM SQUARED: #MISSING
1.2 8 6.8 70.6 408.62 1
Table 6.17, Frequency distribution of post-mitigation activated charcoal measurements
performed in basement area of School G
X,: MARCH 13-15, 1989
FROM: f>i
TO:
_L
-------
*
101
102
102-S
103
104
104-C
105
106
10?
108
109
110
120
121
121-0f:
122
123
124
125
126
126-H
127
128
12B
130
131
Art
Alt-01:
TV-Rm
TV-Ent:
Off-ou'
Off-Pr:
E*U-N1
a«u-N
I-tasa
Qym
G-LkJtm
G-DrRa
B-Dcfim
B-llSu
Mualc
W-Shop
M-Shop
Ball-H
Kit
€¦{•
3aU-E
201
202
207
222
225
231
Lib
TABLE 7.1.1. RADON CONGENTEATIONS MEASURED AT
SCHOOL H (Parti)
February Screening
Meres Date Level Type
JL_ (pCI/U Pet.
February FcLlow Up
Date Level Type
CtCl/L) Pet..
March Mter Sealing
Data Lavsl Typa
CtCl/Li D»t.
28
19
19,1
27
20
20.1
26
21
25
22
24
23
14
1
2
13
3
12
4
11
11.1
5
10
6
S
7
a
02/01/89
40,1
136.2
16.1
108. 7
5.7
116.5
99.7
38.6
25.6
6.2
12.4
29.2
21.7
64.9
51.7
61.3
76.1
2.4
62.5
3.6
10.7
1.5
10.2
13.4
CX
cc
cc
cc
cc
cc
cc
cc
cc
ec
cc
cc
oc
cc
oc
cc
cc
cc
cc
oc
cc
cc
cc
oc
02/15/89 148.B
CC 03/01/89 33.3
41.7
47.6
CC
56.2
CC
38.4
21.0
27.9
22.2
21.3
33.4
29.2
21.8
CC
CC
CC
CC
CC
CC
CC
CC
oc
cc
29
30
*9,1
49
IB
33
37
38
36
34
35
17
16
IS
50
32
31
46
41
40
39
43
44
45
42
42.0
45.9
2.1
53.0
12.fi
10.4
39.5
1.5
136.2
OC
CC
cc
cc
cc
OC
24.1
CC
17.0
CC
69.2
24.1
148.6
27.9
17.0
41.7
B-13
-------
TABLE 7.1.1. RADON CONCENTRATIONS MEASURED AT
SCHOOL H. (Continued, part 2)
Roan
*
Mean
June
Date
Fre-Mit.
Level
(dCI/L!
OC
Type
Det.
June Fre-Hit. E-
Date Level
CcCi/L)
Farm
Type
Det.
Jims
Date
Subslab
Level
(pCl/L)
Lev«l»
Typ«
Det,
101
28
06/01/89
2.9
CC
06/01/S9 1.7
EF
06/06/89
4700
ss-sr.irr
102
19
"
30.8
cc
35.2
IP
"
3600
SS-Soiff
102-S
19.1
4600
SS-Sniff
103
27
2.8
cc
"
2400
SS-Sniff
104
20
"
32.4
OC
"
3700
SS-Sniff
104-C
20.1
"
5200
SS-Sniff
105
2S
"
1.8
cc
"
3500
SS-Snlff
106
21
"
13.2
cc
"
3100
SS-Sniff
107
25
4.1
cc
"
1900
SS-Sniff
108
22
¥t
12.0
cc
7.2
EF
"
1300
SS-Sniff
108
2*
2.9
OC
"
1500
SS-Sniff
110
23
"
7.2
OC
-
1700
S5-Sx>i££
120
14
"
1.8
cc
0.0
EF
"
700
SS-Sniff
121
1
"
12.4
cc
it
800
SS-Sniff
121-Off
2
B.4
cc
it
1200
SS-Sniff
122
13
19.4
cc
"
2200
ss-saiff
123
3
M
7.5
oc
"
2100
SS-SDiff
12*
12
II
23.5
OC
18.9
EE
II
1600
SS-Sniff
125
*
"
7,8
cc
6.0
EE
"
800
SS-Sniff
126
11
"
17.0
cc
200
SS-3niff
126-K
11.1
"
1300
SS-Sniff
127
5
"
14.9
OC
"
300
SS-Sniff
128
10
*«
3.5
OC
129
6
2.4
cc
130
a
6.1
cc
131
7
5.4
cc
3.6
EF
Art
3
"
S.l
cc
"
BOO
SS~Snif£
Act-Off
"
1200
SS-Sniff
TV-Rn»
500
SS-Snlff
TV-Entry
50
SS-Snlff
Off-out
23
2.6
cc
Off-Pli
30
"
4.S
CC
Btii-ra
49.1
"
2400
SS-Sniff
Ball-H
49
"
5700
SS-Snlff
T-LngB
IS
9.0
OC
Gym
33
8.5 •
cc
"
3000
SS-Salff
S-Gym
37
"
3.4
cc
1.6
BP
S-IkSa
36
«'
4.6
OC
4.6
IF
S-BrRm
36
"
35.2
OC
B-DiKm
34
"
12.2
CC
1-IiBa
35
*
11.9
cc
10.8
EF
Hiaic
17
3.4
cc
"
500
SS-Sniff
W-Stiop
is
"
l.S
cc
1.4
EP
"
700
SS-Saiff
M~Shop
15
"
4.4
cc
«
600
SS-Sniff
a»ii-w
50
Kit
32
Cat*
31
4100
SS-Saiff
Hall-S
48
2100
SS-Sniff
201
41
3.3
cc
202
40
"
4.7
cc
207
39
4.3
cc
3.2
EP
222
43
H
3.2
cc
225
44
M
2.B
cc
231
45
3.1
OC
Lib
42
2.9
CC
1.0
EP
Average
Mini nan
HbxIsud
3.9
1.9
35.2
7.3
0.0
35.2
2066
JO
5700
B-14
-------
*
TABLE 7.1.1. RADON CONCENTRATIONS MEASURED AT
SCHOOL H. (Continued, Part 3)
Room
*
H««S
JL
June Post-Mit.
Date L«v*l
{idCI/L)
CC
Typ*
Det.
June
Date
Post-Hit. E-
Level
(cCi/U
•P
Type
Det.
101
28
06/26/89
1.5
CC
102
19
*
3.3
CC
"
3.2
EP
1QZ-5
18,1
103
27
"
1.5
CC
"
1.3
EF
104
20
"
5.3
CC
104-C
20,1
105
26
"
0.9
CC
108
21
2.1
CC
"
2.4
£F
107
25
"
1.5
CC
"
1.3
EP
ioa
22
"
2.1
CC
109
24
1.8
CC
110
23
H
2.3
CC
"
1.9
EP
120
14
n
o:s
CC
"
0.9
EP
121
1
H
2.1
CC
1.8
EP
m-o£f
2
122
13
1.8
CC
123
3
2.*
oc
"
9.9
EP
124
12
"
2.2
CC
"
1.3
IS
125
4
"
1.6
CC
"
1.7
EE
126
11
"
2.2
CC
"
1,7
EE
12S-N
11,2
127
3
2.0
CC
12S
10
"
1.*
CC
129
6
2.5
CC
"
2.6
IP
130
9
H
*.6
CC
"
3.3
ET
131
7
4.6
CC
Art
8
6.2
CC
Art-Off
TV-Rm
TV-Entry
Off-out
29
1.6
CC
"
1.5
EE
Off-pri
30
"
2,0
CC
HaXl-NN
¦$9.1
Hall-N
48
T-Lnga
IS
"
2.1
CC
n
2.2
Ef
Qya
33
"
3,0
CC
G-Qyn
3?
2.3
CC
G-UgIUe
38
w
2.6
CC
G-Drlto
38
"
4.0
CC
B-DrSm
34
"
5.6
CC
8-LkRr
35
"
5.7
CC
Music
17
"
5.9
CC
W-Shop
16
"
1.5
CC
M-Shop
13
"
1,9
CC
Ball-H
50
¦
Kit
32
"
4.0
CC
Cafe
31
"
1.8
CC
n
2.1
H
Hsll-S
48
201
41
202
40
20?
39
222
43
225
44
231
45
Lib
42
Avarage
Hinirauni
Majclajjcc
2.7
0.9
6.2
2.3
0.7
9.9
B-15
-------
TABLE 7.1.1. RADON CONCENTRATIONS MEASURED AT
SCHOOL H. (Continued, Part 4)
Room
#
Hsftfl
July Post-Mit.
Date Level
(cCi/L)
Typ*
Dat,
August Boat-Hit
Date Laval
tcCl/L?
Type
Deb.
101
28
0.5
OC
€8/04/69
o.a
CC
102
19
2.4
DC
"
1.3
CC
102-S
19.1
103
27
0.5
cc
"
1.0
cc
104
20
3.0
cc
"
0.8
cc
104-C
20.1
105
26
0.5
cc
"
0.6
cc
106
21
2.7
cc
"
o.a
cc
107
25
0.5
cc
"
0.5
cc
108
22
1.3
cc
"
0.6
cc
109
24
0.6
OC
"
1,2
cc
110
23
1.5
cc
"
1.0
cc
120
14
1.8
cc
•
0.5
cc
121
1
2.5
cc
-
0.8
cc
121-Qff
2
2.1
cc
"
0,8
cc
122
13
1.7
cc
"
0.6
cc
123
3
1.8
cc
"
0.6
cc
124
12
1.7
cc
"
0.6
cc
125
4
0.0
cc
"
0.5
cc
126
11
1.5
cc
"
0.8
cc
126-N
11.1
12?
5
1.1
cc
"
0.5
cc
128
10
3.5
cc
"
0.5
cc
129
6
1.5
cc
"
1.0
cc
130
a
8.4
OC
"
0.5
cc
131
7
4.8
OC
•
0.5
cc
Art
8
IS.8
cc
"
0.8
cc
Art-Qff
IT-Rb
"
0,5
cc
TV-Entry
0€£-out
28
0.5
cc
"
0,7
cc
Off-Pxi.
30
0.6
cc
"
0.6
cc
HaU-BH
48.1
1.0
cc
H*U-K
48
0.7
OC
T-imse
IB
1.3
OC
"
0.6
cc
Gym
33
2,0
cc
G-Gyn
37
1.8
cc
G-IkR»
36
7.8
cc
G-Drftn
36
1.8
cc
B-DrHm
34
7.4
cc
B-tiSm
35
7.4
cc
Music
17
0.5
cc
"
2,2
cc
W-Shop
16
1.2
cc
0.8
cc
M-Shop
15
1.3
OC
"
0.8
cc
Eall-W
50
1.1
cc
Kit
32
0.6
OC
"
0.6
cc
Cafe
31
1.0
OC
¦*
0,6
cc
HaLl-8
48
2.2
OC
201
41
"
1.0
cc
202
40
0,8
cc
20?
39
"
0,8
cc
222
43
"
1.2
cc
225
44
*
0.6
cc
231
42
0,5
cc
Lib
42
**
l.l'
cc
Avarage
Minimum
Hftzimuto
2,6
0,5
is,8
0.8
0.5
2.2
B-16
-------
7.1.1. RADON CONCENTRATIONS MEASURED AT
SCHOOL H. (Continued, Part 5)
Deceobac Peat-Mit. Post-Mit
Baaa Hats Data Level Type Data Lovel Type
_J t, (tCl/L) Pet. (tCl/L) 0«t.
101
28
12/1/89
6.4
CC
1/12/90
0.3
CC
102
19
**
1.8
CC
"
1.1
CC
102-S
19.1
103
27
"
4.8
0c
"
a.6
cc
10*
20
"
1.6
oc
"
1,3
CC
104-C
20.1
105
26
»
2.9
CC
0.5
cc
106
21
"
0.8
oc
"
1.0
CC
107
25
-
38.0
oc
"
0,5
CC
108
22
24.8
oc
"
1.1
CC
109
24
"
5.4
oc
"
0.9
CC
110
23
"
5.7
oc
-
1.0
CC
120
1*
oc
121
1
"
1.3
oc
121-Off
2
"
1.0
CC
122
13
"
0.7
CC
123
3
"
1.0
oc
12*
12
"
0.8
oc
125
4
"
1.3
oc
126
11 .
"
1.5
oc
126-M
11.1
127
5
"
3.6
oc
123
10
"
0.8
CC
129
6
"
1.8
oc
130
9
"
0.6
CC
131
7
"
1.5
oc
Art
8
"
l.S
CC
Axt.-0£f
TV-lo
TV-Entry
Gl£-out
28
"
7.2
CC
1.0
CC
Off-Pri
30
lall-NH
19.1
Hall-H
49
T-Lnga
18
*"
2.5
oc
Qyw
33
"
21.4
oc
37
38
G-PeSb
36
"
34.2
CC
1-DeBb
24
"
11.6
CC
S-LUtm
35
"
13.8
oc
(bale
17
"
24.8
oc
0.5
CC
W-Shep
16
4.6
oc
"
0.8
CC
H-Shop
15
"
3.5
oc
a«u-H
SO
Kit
32
"
5.0
oc
0.5
CC
31
"
5.4
oc
"
0.7
CC
BaU-S
48
201
41
202
40
207
39
222
43
225
4*
231
45
Lib
42
Average
7.2
0.8
Minimus)
0.6
0.5
Maximum
38.0
1.3
B-17
-------
TABLE 7.1.2. PRE-MITIGATION SUBSLAB COMMUNICATION TEST DATA PART 1.
Vacuum Orifice (^"Cl*Dp~c2
Dia "
0.375
0.75
1.1875
CI
1.7729
3.256
28.366
C2
0.5015
0.461
0.472
SubSlab Conmunication Data Sheet Sheet f: 1
Number
Investigator: SRI/EPA Date: 06/05/89 HouaelD# School H
1
Numb or of orifice used: NA 2
Show location of all holes on floor plant 3
Alnor
DATA
Closet Rm 104 Km 104 Rm 102N Km 102S Ball Rml04 Km 105 Rm 105E Rm 106S Rm 106N
Suction Point (Fb) (Fc) (Fd) (Fa) (Ft) (Fg) (Fh) (Fi)
(Fa) 15 'to Fa 13 'to Fa 39 'to Fa 12 'to Fa 30 'to Fa 40 'to Fa 33 'to Fa 57 'to Fa
Dp Flow rata Dp Flowrate Dp F Low rata Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
-------
TABLE 7.1.3. PRE-MITIGATION SUBSLAB COMMUNICATION DATA PART 2.
SubSlab Comnunication Data Sheet Sheet #: 2
Vacuum Orifice Q-cl*DpAc2
Number Die
Investigator: SRI/EPA
Date: 06/05/89 HouselD# School H
Number of orifice used: NA
Show location of all holes on floor plenf
0.375
0.75
1.1875
Alnor
CI C2
1.7729 0.5015
6.256 0.461
28.366 0.472
-0.012 0.00058 Q-cl+c2*Val
Closet Red 104
Suction Point
(Fa)
Rm 108
CFb)
84 'to
Rm 110
(Fc)
112 'to
Rm 109
(Fd)
117 'to
--RAW DATA
Ball Rral07/109
CFe)
Fa 97 'to Fa
Rm 101
Office
(Ff) (Fg) (Fh) (Fi)
Fa 112 'to Fa 117 'to Fa 97 'to Fa 58 *to Fa 84 'to Fa 'to Fa 'to Fa
Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
(Pa/'WC) (u.u.) (Pa/"WC) (u.u.) (Pa/"DC) (u.u.) (Fa/*WC> (u.u.) (Pa/'WC) (u.u.) (Pa/'HC) (u.u.) (Pa/'VC) (u.u.)
-------
TABLE 7.1.4. PRE-MITIGATION SUBSLAB COMMUNICATION DATA PART 3.
SubSlab Cotununication Data Sheet Sheet f: 3
Vacuus Orifice Q-cl*Dp~c2
Number Dla *
CI
C2
Investigator: SRI/EPA
Date: 06/05/89 HouaelD# School H
0.375
0.75
1.1875
1.7729
8.256
28.366
0.5015
0.481
0 .472
-0.012 0.00058 Q-ol+c2*Val
Number of orifice used: NA
Show location of all holes on floor plan I
Alitor
DATA
Rm 121 Office Dm 121 Hall Rml23 Rm 123 Rm 125 Rm 127 Rm 126 Rm 124
Suction Point (Fb) (Fc) (Fd) (Fe) (Ff) (Fg) (Fh)
(Fa) 37 'to Fa 11 'to Fa 23 'to Fa 54 'to Fa 89 'to Fa 103 'to Fa 51 'to Fa
Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
(Pa/"WC)
-------
TABLE 7.1.5. POST-MITIGATION SUBSLAB COMMUNICATION DATA WITH TEMPORARY SYSTEM PART 1.
Investigator:
SubSlab Commmication Data Sheet Sheet #: S
SRI/EPA Date: 06/28/89 HouselD# School B
Number of orifice used: HA
Show location of all holes on floor plant
Vaeuun Orifice Q"C l*Dp"c2
Number Dia " CI C2
1 0.375 1.7729 0.5015
2 0.75 8.256 0.481
3 1.1875 28.366 0.472
Alitor -0.012 0.00058 Q-cl+c2*Val
- RAW DATA
Closet Rml04 Rm 102S Rm 102N Rm 106S Rm 10EN Rm 108 Rm 110 Ball RnilOS Ball Rml04
Suction Point (Fb) (Fc) (Fd) (Fe) (F£) (Fg) (Fg) (Fh) (Fi)
(Fa) 39 'to Fa 13 #to Fa 33 'to Fa 57 'to Fa 84 'to Fa 112 'to Fa 97 'to Fa 12 'to Fa
Dp Flowrate Dp Flcwrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
(Pa/"WC) (cfm) (Pa/"WC) (efta) (Pa/'HC) (cfta) (Pa/"WC) (cfin) (Pa/"WC) (cfln) (Pa/"WC) (cfln) (Pa/"HC) (u.u.) (Pa/'HC) (u.u.) (Pa/"WC) (u.u.)
1.91 192.00 0.183 NA 0.347 NA 0.256 NA 0.199 NA 0.005 NA 0.004 NA 0.005 NA 0.357 NA
NA NA NA NA NA NA NA NA NA
NA NA NA NA NA NA NA NA NA
NA NA NA NA NA NA NA NA NA
NA NA NA NA NA NA NA NA NA
NA HA NA NA NA NA NA NA NA
NA NA NA NA NA NA NA NA NA
NA NA NA NA NA NA NA NA NA
NA NA NA NA NA NA NA NA NA
Conxnents(e.g. Orifice used, etc)Flowrate data not available for test points
Suction provided by temporary mitigation system
-------
TABLE 7.1.6 POST-MITIGATION SUBSLAB COMMUNICATION DATA WITH TEMPORARY SYSTEM PART 2.
SubSlsb Commmication Data Sheet Sheet #: 6 Vacura Orifice 0"cl*Dp~c2
Number Dia " CI C2
Investigator: SRI/EPA Date: 06/28/89 HouselD# School B
1 0.375 1.7729 0.5015
Number of orifice used: HA 2 0.75 8.256 0.481
Show location of all holes on floor planl 3 1.1875 28.366 0.472
Alnor -0.012 0.00058 Q-cl+c2*Val
RAW data- -
Closet Rml04 Office Rm 103 Rm 107 Rm 109
Suction Point (Fb) (Fc) (Fd) (Fe) (Ff) (Fg) (clta) (Pa/"HC) (u.u.) (Pa/"WC) (u.u.) (P«/"VC) (u.u.)
1.91 192.00 0.098 NA 0.222 NA 0.005 NA 0.004 NA NA NA NA NA
NA NA NA NA NA NA NA NA NA
NA NA NA NA NA NA HA NA NA
NA NA NA HA NA NA NA NA NA
NA NA ^ NA NA NA NA HA NA NA
FA NA NA NA NA NA NA NA NA
NA NA NA HA NA NA NA NA NA
HA NA NA NA NA NA NA NA NA
NA NA NA NA NA NA HA NA NA
Comnents(e.g. Orifice used, etc)Flowrate data not available for test points
Suction provided by temporary mitigation system
-------
TABLE 7.1.7 POST-MITIGATION SUBSLAB COMMUNICATION DATA WITH TEMPORARY SYSTEM PART 3.
Investigator:
SubSlab Coenunlcation Data Sheet Sheet #: 7
SRI/EPA Date: 06/28/89 HouselD# School H
Dumber of orifice used: NA
Show Location of all holes on floor plan!
Vacum Orifice Q-c^Dp"^
Number Dia " CI C2
1 0.375 1.7729 0.5015
2 0.75 6.256 0.481
3 1.1875 28.366 0.472
Alnor -0.012 0.00058 Q-cl+c2*Val
RAW DATA
Office Rml21 Rm 121 Rm 123 Rm 125 Rm 127 Rm 126S Rid 126H Rm 124 Rm 122
Suction Point (Fb) (Fc) (Fd) (Fe) (Ff) (Fg) (Fh) (Fi)
(Fa) 37 'to Fa 23 'to Fa 54 'to Fa 89 'to Fa 103 'to Fa 90 'to Fa 51 'to Fa 25 'to Fa
Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
(Pa/"WC) (u.u.) (Pa/"WC) (u.u.) (Pa/"WC) (u.u.) (Pa/"WC) (u.u.) (Pa/'W:) (u.u.)
co
Notes: Suction point Dp's should range from 0 to 5000 Fa (20"WC) if possible
u.u. are user units for the device used to monitor flow (before conversion)
use additional data sheets for more test points
- REDUCED DATA - "
Suction Point (Fb) (Fc) (Fd) (Fe) (Ff) (Fg) (Fh) (Fi)
(Fa) 37 'to Fa 23 'to Fa 54 'to Fa 89 'to Fa 103 'to Fa 90 'to Fa 51 'to Fa 25 'to Fa
Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
(Pa/'W:) (cfm) (Pa/"WC) (cfin)
-------
TABLE 7.1.8 POST-MITIGATION SUBSLAB COMMUNICATION DATA WITH TEMPORARY SYSTEM PART 4.
SubSlab Comnunication Data Sheet Sheet #: 8 Vacum Orifice Q~cl*Dp~c2
Number Die " CI C2
Investigator: SRI/EPA Date: 06/28/89 HouaelD# School H
1 0.375 1.7729 0.5015
Number of orifice uaed; HA 2 0.75 8.258 0.481
Show location of all holes on floor plan! 3 1.1675 28.386 0.472
Alnor -0.012 0.00058 Q-cl+c2*Val
RAH DATA -
Office Rml21 Rm 120 Cafeteria
Suction Point (Fb) (Fc) (Fd> (Fe) CFf) (Fg) (Fh) (Fi)
(Fa) 25 'to Fa 90 'to Fa 'to Fa 'to Fa 'to Fa "to Fa 'to Fa 'to Fa
Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
(Pa/"WC) (u.u.) (Ta/"WC) (u.u.) (Pa/"HC) (u.u.) (Pa/"WC) (u.u.) (Pa/"WC) (u.u.) (Pa/"HC) (u.u.) (Pa/'WC) (u.u.)
-------
TABLE 7.1.9 POST-MITIGATION SUBSLAB COMMUNICATION DATA WITH PERMANENT SYSTEM PART 1.
Investigator:
SubSLab Connmnication Data Sheet Sheet #: 9
SRI/EPA Date: 08/04/89 HouselDf School B
Vacuun Orifice Q"cl*Dp"c2
Number Dla " CI C2
Number of orifice used: NA
Show location of all holes on floor plant
Office RmlZl
Suction Point
(Fa)
Dp Flowrate
1 0.375 1.7729 0.5015
2 0.73 8.256 0.481
3 1.1675 28.366 0.472
Alnor -0.012 0.00058 Q-ol+c2*Val
RAW DATA -
Hall Rml23 Rm 123 Rm 122 Rm 125 Dm 124 Rm 127 Rm 126
(Fb) (Fc) (Fd) (Fe) (Ff) (Fg) (Fh) (Fi)
37 'to Fa 11 'to Fa 23 'to Fa 25 'to Fa 54 'to Fa 51 'to Fa 89 'to Fa 103 'to Fa
Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
Rm 121
(Pa/"WC) (u.u.) (Pa/"WC) (u.u.)
-------
TABLE 7.1.10 . POST-MITIGATION SUBSLAB COMMUNICATION DATA WITH PERMANENT SYSTEM PART 2.
Investigator:
SubSlab Caimunlcation Data Sheet Sheet #: 10
SRI/EPA Date: 08/04/89 HouselD# School H
Number of orifice used: NA
Show location of all holes on floor planI
Vacuum Orifice Q™cl*Dp~c2
Nunfcer Die " CI C2
1 0.375 1.7729 0.5015
2 0.75 8.256 0.481
3 1.1875 28.366 0.472
Alnor -0.012 0.00058 Q-cl+c2*Val
RAW DATA —
Closet Rm 104 Rm 104 Rm 102N Rm 102S Hall Rml04 Rm 105 Rm 103 • Rm 106S Rm 108
Suction Point (Fb) (Fc) (Fd) (Fe) (Ff) (Fg) (Fh) (Fi)
(Fa) 15 'to Fa 13 'to Fa 39 'to Fa 12 'to Fa 30 'to Fa 38 'to Fa 33 'to Fa 97 'to Fa
Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp FLowrato Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
(Pa/"WC) (u.u.) (Pa/"WC) (u.u.) (Pa/"HC) (u.u.) (Pa/"WC) (u.u.)
Notes: Suction point Dp's should range from 0 to 5000 Pa (20"WC) if possible
u.u. are user units for the device used to monitor flow (before conversion)
use additional dsta sheets for more test points
REDUCED DATA -
Suction Point (Fb) (Fc) (Fd) (Fe) (Ff) (Fg) (Fh) (Fi)
(Fa) 15 'to Fa 13 'to Fa 39 'to Fa 12 'to Fa 30 'to Fa 38 'to Fa 33 'to Fa 97 'to Fa
Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
(Pa/"WC) (cfin) (Pa/"WC) (efm) (Pa/"WC) (cfln) (Pa/"WC) (cfln) (Fa/"HC) (ofin) (Pa/"WC) (cfin) (Pa/"WC) (u.u.) (Pa/"HC) (u.u.) (Pa/"HC) (u.u.)
1.91 180.00 0.369 NA 0.366 NA 0.204 NA 0.392
NA NA NA NA
NA NA NA NA
NA NA NA NA
NA NA NA NA
NA NA NA NA
NA NA NA NA
NA NA NA NA
NA NA NA NA
NA 0.271 NA 0.239 NA 0.269 NA 0.006 NA
NA NA NA NA NA
NA NA NA NA NA
NA NA NA NA NA
NA NA NA NA NA
NA NA NA NA NA
NA NA NA NA NA
NA NA NA NA NA
NA NA NA NA NA
Coranents(e.g. Orifice used, etc)No flowrate data available at test points
Suction provided by final mitigation system is Rm 104
-------
TABLE 7.1.11 POST-MITIGATION SUBSLAB COMMUNICATION DATA WITH PERMANENT SYSTEM PART 3.
SubSlab Commmication Data Sheet Sheet t: 11
Investigator: SRI/EPA
Date: 08/06/89 HouselDf School H
Nun&er of orifice used: NA
Show location of all holes on floor plant
Closet Rm 104
Suction Point
(Fa)
Office
Km 107
Rm 109
-RAW DATA-
Rm 110
(Fb)
64 'to Fa
(Fc)
63 'to Fa
-------
TABLE 7.1.12 POST-MITIGATION SUBSLAB COMMUNICATION DATA WITH PERMANENT SYSTEM PART 4.
SubSlab Communication Data Shaet Sheet #: 12 Vacuirn Orifice Q™cl*Dp~c2
Number Dia " CI C2
Investigator: SRI/EPA Date: 08/04/89 HouselD# School H
1 0.375 1.7729 0.5015
Nunfcer of orifice uaed: NA 2 0.75 8.256 0.481
Show location of all holes on floor planl 3 1.1875 28.368 0.472
Alnor -0.012 0.00058 Q-cl+c2*Val
DATA
Art Room Art Km TV Room
Suction Point (Fb) (Fc) (Fd) (Fe) (Ff) (Fg) (Fh) (u.u.) (Pa/"HC) (u.u.) (Pa/"WC)
-------
TABLE 7.1.13. ESTIMATED MATERIAL COSTS AND WORK-HOUR EXPENDITURE
FOE MITIGATION OF SCHOOL H.
Material Costs
Plumbing Supplies §1,036.08
Hole Coring 368.00
Fans and Couplings 1,044.78
Fire Stop Materials 275.29
Pressure Switches 79.35
Misc. Plumbing and Electrical Supplies 568.34
Total Materials $3,371.84 3,371.84
Travel Costs
Vehicle Rental 1,645.28
Per Deim 1,560.00
Work-Hour Costs
Pre-Mitigation Diagnostics
Team Leader 40 Hours @$30 - $1,200
Technician 40 15 600
Technician 40 15 600
Mitigation Installation
Team Leader 40 30 1,200
Technician 40 15 600
Plumber 40 18 720
Electrician 40 18 720
Post-Mitigation Diagnostics
Team Leader 20 30 600
Technician 20 15 300
Sub-Totals 320 6,540
25* Fringe Benefits 1,635
Total Labor Costs $8,175 8,175.00
Total Labor and Materials $14,752.12
25% Overhead 3,688.03
25% Profit 3,688.03
Total Mitigation Cost $22,128.18
8-29
-------
Table 7.2.1. RADON CONCENTRATIONS MEASURED AT
SCHOOL I (Part 1}
February Screening
February Follow
Room
Meas
Date
Level
Type
Date Level
#
#
(pCi/L)
Det.
(p«/l:
Office
1 02/01/89
28.4
C€
Work rm
24
R
32.2
cc
T-Lnge
23
Aud
25
cc
101
22
cc
102
21
n
40.4
02/15/89 30.0
103
20
it
36.0
cc
104
19
n
30.7
cc
105
cc
106
18
«¦
34.8
cc
107
17
H
29.9
cc
109
2
H
36.9
cc
110
3
n
38.6
cc
110-Wall
110-Hall
111
4
n
40.1
cc
41.4
112
5
H
27.7
cc
113
6
n
52.5
cc
36.1
114
7
n
39.9
cc
115
8
n
24.8
cc
116
9
n
8.9
cc
117
10
*
9.9
cc
118
11
t«
10.8
119
12
it
9.1
cc
120
13
n
44.8
cc
42.6
121
14
n
24.9
cc
122
15
n
24.0
cc
123
16
n
27.4
cc
Average
29.7
37.5
Minimum
8.9
30,0
Maximum
52.5
42.6
B-30
-------
Table 7.2.1. RADON CONCENTRATIONS MEASURED AT
SCHOOL I. (Continued, Pare 2}
June Fre-Mit. CC June Subslab Levels
Room Meas Date Level Type Date Level Type
# # (pCi/L) Det, (pCi/L) Det.
Office
1 06/01/89
11.2
CC
Work rm
24
K
6.4
CC
T-Lrtge
23
Aud
25
n
14.7
CC
06/06/89
1900
SS-Sniff
101
22
ft
20.5
CC
If
400
SS-Sniff
102
21
18.8
CC
n
400
SS-Sniff
103
20
n
19.5
CC
n
1200
SS-Sniff
104
19
14.2
CC
14
800
SS-Sniff
105
it
500
SS-Sniff
106
18
n
15.1
CC
«
300
SS-Sniff
107
17
n
9.2
CC
N
800
SS-Sniff
109
2
n
30.6
CC
n
800
SS-Sniff
110
3
H
53.4
CC
n
800
SS-Sniff
110-Wall
n
1500
SS-Sniff
110-Hall
N
300
SS-Sniff
111
4
it
59.6
CC
n
1300
SS-Sniff
112
5
H
17.0
CC
113
6
it
13.4
CC
114
7
fi
16.1
CC
115
8
it
18.4
CC
116
9
it
3.2
CC
117
10
M
9.0
CC
118
11
ft
5.8
CC
119
12
R
4.6
CC
120
13
rt
93.4
CC
it
600
SS-Sniff
121
14
n
22.9
CC
122
15
123
16
Average
21.7
829
Minimum
3.2
300
Maximum
93.4
1900
B-31
-------
Table 7.2.1. RADON CONCENTRATIONS MEASURED AT
SCHOOL I.(Continued, Part 3)
July Pre-Mit. CC August Post-Mit. CC
Room Me as Date Level Type Date Level Type
# # (pCi/L) Det, (pCi/L) Det.
Office
1
9.8
CC
08/19/89
1.3
CC
Work rm
24
10.1
CC
"
1.4
CC
T-Lnge
23
14.6
CC
tf
0.8
CC
Aud
25
31.3
CC
R
1.4
CC
101
22
22.8
CC
ft
1.4
CC
102
21
28.9
CC
ft
1.8
CC
103
20
34.7
CC
n
1.2
CC
104
19
36.9
CC
it
1.3
CC
105
106
18
28.5
CC
N
1.5
CC
107
17
22.9
CC
II
2.0
CC
109
2
12.3
CC
It
1.7
CC
110
3
29.5
CC
11
2.3
CC
110-Hall
110-Hall
-
111
4
32.7
CC
it
2.4
CC
112
5
6.1
CC
II
2.1
CC
113
6
4.4
CC
n
1.6
CC
114
7
30.5
CC
It
1.7
CC
115
8
20.1
CC
n
2,8
CC
116
9
11.3
CC
n
3.6
CC
117
10
11.4
CC
it
4.0
CC
118
11
6.1
CC
tt
3.8
CC
119
12
5.2
CC
n
3.1
CC
120
13
108.9
CC
n
2.9
CC
121
14
23.9
CC
R
1.5
CC
122
15
14.5
CC
«
1.1
CC
123
16
15.0
CC
Average
22.9
2.0
Minimum
4.4
0.8
Maximum
108.9
4.0
B-32
1
-------
Table 7.2.1. RADON CONCENTRATIONS MEASURED AT
SCHOOL I.(Continued, Part 4)
December
Post-Mit
. cc
Jan 90
Post-Mit.
CC
Room
Me as '
Date
Level
Type
Date
Level
Type
#
#
(pCi/L)
Det.
(pCi/L)
Det.
Office
1 12/01/89
7.2
CC
01/13/90
3.9
CC
Work ra
24
n
2.0
CC
11
0.8
CC
T-Lnge
23
Aud
25
rt
2.9
CC
n
1.9
CC
101
22
n
3.0
CC
ii
1,4
CC
102
21
n
3.4
CC
it
2.8
CC
103
20
it
3.3
CC
!•
2.5
CC
104
19
fi
3.7
CC
n
5.5
CC
105
106
18
i)
3.0
CC
it
3.2
CC
107
17
IT
4.6
CC
n
2.4
CC
109
2
11
12.7
CC
n
3.9
CC
110
3
It
20.1
CC
n
1.2
CC
110-Wall
110-Hall
111
4
n
3.0
CC
ft
1.3
CC
112
5
n
2.4
CC
113
6
n
2.1
CC
114
7
ii
1.4
CC
115
8
n
2.0
CC
116
9
it
8.9
CC
117
10
n
9.8
CC
118
11
n
7.5
CC
119
12
it
4.4
CC
120
13
It
40.4
CC
ft
6.4
CC
121
14
n
2.5
CC
*
2.1
CC
122
15
n
1.5
CC
123
16
n
2.3
CC
Average
6.6
2.8
Minimum
1.4
0.8
Maximum
40.4
6.4
B-33
-------
Table 7.2.1. RADON CONCENTRATIONS MEASURED AT
SCHOOL I.(Continued, Part 5)
Feb 90
Post-Mit.
CC
Room
Meas
Date
Level
Type
#
#
(pCi/L)
Det.
Office
1
02/02/90
1.7
CC
Work rm
24
T-Lnge
23
n
0.6
CC
Aud
25
n
0.6
CC
101
22
n
1.8
CC
102
21
It
1.3
CC
103
20
II
1.6
CC
104
19
"
1.2
CC
105
106
18
n
1,5
CC
107
17
H J
1.5
CC
109
2
II
1.2
CC
110
3
n
3.0
CC
110-Wall
110-Hall
f
111
4
H
3.5
CC
112
5
113
6
114
7
115
8
116
9
117
10
118
11
119
12
120
13
II
3.4
CC
121
14
H
2.5
CC
122
15
"
1,3
CG
123
16
n
0.5
CC
Average
1.7
Minimum
0.5
Maximum
3.5
6-34
-------
TABLE 7.2.2. PRE-MITIGATION SUBSLAB COMMUNICATION DATA PART 1.
SubSlab Corammication Data Sheet Sheet #: 1
Vacuun Orifice (^cl*Dp""c2
Hunger Dla
Investigator: SRI/EPA
Date: 06/06/09 HouselD# School I
Number of orifice used: NA
Show location of all holes on floor plant
0.375
0.75
1.1875
CI
1.7729
8.256
28.366
C2
0.5015
0.461
0.472
Alnor
-0.012 0.00056 Q-cl+c2«Val
Door RmllO Rm 110 Ball RmllO
Suction Point (Fb) (Fc)
(Fa) 14 'to Fa 9 *to Fa
Dp Flowrate Dp Flowrate Dp Flowrate
-RAW DATA-
Rm 111 Rm 107
(Fd)
30 'to Fa
Dp Flowrate
Rm 120
(Fe)
45 'to Fa
Dp Flowrate
(cfta) (Pa/"WC) (cfta) (Pa/'WC) (cfta) (Pa/"WC) (u.u.) (Pa/"VC) (u.u.) (Pa/"tC) (u.u.)
4
NA
0.015
0.12
0.003
0.02
0
-0.00
0
HA
0
NA
NA
NA
NA
S
NA
0.018
0.14
0.004
0.03
0.002
0.00
0
-0.00
0
NA
HA
NA
NA
8
NA
0.025
0.15
0.004
0.03
0.002
0.01
0.001
0.00
0
NA
HA
NA
NA
NA
NA
NA
NA
NA
HA
HA
HA
NA
HA
NA
NA
NA
NA
NA
HA
NA
NA
NA
NA
NA
NA
NA
MA
NA
NA
NA
HA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
HA
NA
NA
NA
NA
HA
NA
NA
NA
HA
NA
NA
NA
NA
CoomentsCe.g. Orifice used, etc)Original Building West Wing
-------
TABLE 7.2.3. PRE-MITIGATION SUBSLAB COMMUNICATION DATA PART 2.
SubSZab Comnunieation Data Sheet Sheet #: 2 Vacuum Orifice (^cl*Dp"c2
Nunfcer Dla " CI C2
Investigator: SRI/EPA Date: 06/07/89 HousalD# School I
1 0.375 1.7726 0.5015
Nun&er of orifice used: NA 2 0.75 8.256 0.AS1
Show location of all holes on floor plan! 3 1.1875 28.366 0.472
Almor -0.012 0.00058 Q-el+c2*Val
RAH DATA -
Root 105 An 106 Rm 107 Cafeteria Rm 101 Rm 102 Rn> 102B Rm 104
Suction Point (Fb) (Fc) (Fd) (Fe) (Ft) (Fg) (Fh) (Fi)
(Fa) 1* -to Fa S 'to Fa 30 'to Fa 45 'to Fa 33 "to Fa 'to Fa 'to Fa 'to Fa
Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
(Pa/"WC) (u.u.) (Pa/"WC) (u.u.) (Pa/"WC) (u.u.) (Pa/"VC) (u.u.) (Pa/"HC) (u.u.) (Pa/"V*:) (u.u.) (Pa/"HC) (u.u.) (Pa/"HC)
-------
TABLE 7.2.4. PRE-MITIGATION SUBSLAB COMMUNICATION DATA PART 3.
SubSlab Corammication Data Sheet Sheet #: 3
Investigator: SRI/EPA
Date: 06/07/89 HouaelD# School I
Number of orifice used: NA
Show location of all holes on floor pl_anl
Vacuum Orifice Q-cl*Dp"c2
Number Dia " CI C2
1 0.375 1.7729 0.5015
2 0.75 8.256 0.481
3 1.1875 28.366 0.472
Alnor -0.012 0.00058 Q-cl+c2*Val
data— -
Ball Rid 108 Rm 106 Rm 107 Cafeteria
Suction Point (Fb) (Fc) (Fd) (Fe) (Ff) (Fg) (Fh) (Fi)
(Fa) 20 'to Fa 24 'to Fa 52 'to Fa 'to Fa 'to Fa 'to Fa 'to Fa 'to Fa
Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
(Pa/"WC) (u.u.) (Pa/"W:) (u.u.) (Pa/"WC> (u.u.) (P«/"VC) (u.u.) (Pa/"WC> (u.u.) (Pa/MWC) (u.u.) (Pa/"WC) (u.u.) (Pa/"M:) (u.u.) (Pa/"HC) (u,u.)
NA 0.006
NA 0.006
100
130
0
0.001
0
25
Notes: Suction point Dp's should range from 0 to 5000 Pa (20"WC) if possible
u.u. are user units for the danrice used to monitor flow (before conversion)
use additional data sheets for more test points
REDUCED DATA
Suction Point (Fb) (Fe) (Fd) (Fe) (Ft) (Fg) (Fh) (Fi)
(Fa) 20 'to Fa 24 'to Fa 52 'to Fa "to Fa 'to Fa 'to Fa 'to Fa 'to Fa
Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
-------
TABLE 7.2.5. PRE-MITIGATION SUBSLAB COMMUNICATION DATA PART 4.
SubSlab Coomunication Data Sheet Sheet #: 4
Vacuus Orifice Q""cl*DpAe2
Number Dla
Investigator:
SRI/EPA
Date: 06/07/89 HouselD# School I
Number of orifice used: NA
Show location of all holes on floor plan!
0.375
0.75
1.1875
CI
1.7729
8.256
28.366
CI
0.5015
0.481
0.472
Alnor
-0.012 0.00058 <>cl+c2*Val
RAW DATA
Room 114 Rm 114 Rm 115 Rm 113 Kzn 112
Suction Point (Fb) (Fd) (Fe)
(Fa) 20 'to Fa 28 'to Fa 30 'to Fa 32 *to Fa
Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate Dp Flowrate
Dp
(Ff)
• to Fa
Flowrate
Dp
(Fb)
'to Fa
Flcmrate
Dp
(Fh)
'to Fa
Flowrate
Dp
(Fi)
•to Fa
Flowrate
(Pa/"W:) (cfta) (Pa/'VC) (u.u.) (Pa/"W:) (u,u.) (Pa/"VC) (u.u.)
4 NA 0.02 0.10 0.01 0.40 0.01 0.00 0.004 0.03 NA NA NA NA
6.5 NA 0.03 0.13 0.02 0.45 0.012 0.10 0.005 0.31 NA NA NA NA
NA NA NA NA NA NA . NA NA NA
NA NA NA NA NA NA NA NA NA
NA NA NA NA NA NA NA NA NA
NA NA NA NA NA NA NA NA NA
NA NA NA NA NA NA NA NA NA
NA NA NA NA NA NA NA NA NA
NA NA NA NA NA NA NA NA NA
Consents(e,g. Orifice used, etc)1957 Addition
-------
TABLE 7.2.6. ESTIMATED MATERIAL COSTS AND WORK-HOUR EXPENDITURE
FOR MITIGATION OF SCHOOL I.
Material Costs
Plumbing Supplies $1,988.54
Hole Coring 563.00
Fans and Couplings 795.74
Fire Stop Materials 550.58
Pressure Switches 79.35
Misc. Plumbing and Electrical Supplies 568.34
Total Materials $4,545.55
4,545.55
Travel Costs
Vehicle Rental
Per Deim
Work-Hour Costs
$1,645.28
1,560.00
Pre-Mitigation Diagnostics
Team Leader 20 Hours @$30
Technician
Technician
20
20
15
15
600
300
300
Mitigation Installation
Team Leader 40
Technician 40
Plumber 60
Electrician 60
30
15
18
18
1,200
600
1,080
1,080
Post-Mitigation Diagnostics
Team Leader 20
Technician 30
Sub-Totals 310
25% Fringe Benefits
30
15
600
450
6,210
1,538
Total Labor Costs $7,688 7,688.00
Total Labor and Materials $15,438.83
25% Overhead 3,859.71
25% Profit 3,859.71
Total Mitigation Costs $23,158.2 5
B-39
-------
TABLE 7.3.1. SCHOOL J RADON MEASUREMENTS
CC Data
Canister
Number
Roam
Usage
Feb 89
(pCi/L)
Follow-Up
CG
Feb 89
(pCi/L)
Subslab
Levels
Jun 89
(pCi/L)
CC Data
July 89
(pCi/L)
1
Class Room
7.4
1.7
2
Class Room
35.4
18.1
170
12.7
3
Class Room
81.9
47.5
845
47.6
-
Hall Room 3
526
4
Class Room
12.0
5.7
5
Class Room
7.6
6.9
6
Class Room
4.1
15.8
7
Bsmt Class Room
13.2
10.7
8
Bsmt Class Room
13.6
10.7
9
Class Room
4.9
10
Class Room
66.4
32.9
238
16.4
11
f'l aoa Dnnm
V>i.alBa IvUUllI
62.0
45.7
195
4.1
12
Teachers Lounge
5.4
13
Class Room
12.9
2 64
7.8
14
Class Room
6.1
76
4.7
-
Hall Room 14
123
15
Class Room
15.2
- 139
16.7
16
Class Room
7.8
142
22.3
17
Class Room
30.7
205
21.6
18
Class Room
24.6
295
4.5
19
Class Room
15.8
341
6.2
20
CI ass Room
26.7
SB5
6.9
21
Office
47.8
1.6
22
Office
54.0
1.2
23
Office
51.9
10.1
1.4
24
Office
49.8
1.4
25
Office
1.2
26
Cafe/Auditorium
12.2
27
Boiler Room
0.5
28
Unknown
9.9
29
Unknown
10.0
30
Unknown
14.4
Minimum = 4.1
Maximum = 81.9
Average = 29.4
10.1 76 0.5
47.5 845 47.6
30.9 296 9.6
B-40
-------
TABLE 7,4.1. SCHOOL K RADON MEASUREMENTS
Canister
Number
Room
Usage
1
2
3
4
5
6
8
9
10
11
12
13
14.
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Front Office
Principal
Teachers' Lounge
Sick Room
Class Room
Class Room
Class Room 6
Hall Room 6
Class Room
Hall Room 8
Class Room
Class Room
Class Room
Class Room
Class Room
Hall Room 12
Class Room
Class Room
Library
Library Office
Class Room
Class Room 16
Hall Room 16
Class Room
Class Room
Class Room
Class Room
Class Room
Class Room
class Room
Class Room
Class Room
Hall Room 25
Class Room
Class Room 26
Class Room
Class Room
Cafeteria •
CC Data
Feb 89
(pci/L)
17.1
13.9
25.2
17.9
7.3
4,0
Follow-Up
CC
Feb 89
(pci/L)
11.3
22.6
28.3
21.7
8.5
4.2
1.2
3.7
1.6
4.4
9.4
6.
3.
4.
12.
11.
8.3
52.0
15.9
70.1
29.9
33
36
61
40
392
290
4
35.1
15.2
Subslab
Levels
Jun 89
(pci/L)
9.4
9.4
9.6
10.1
2.0
2.3
5.7
5.8
6.3
19.1
12.5
7.9
9.5
6.9
¦ 11.0
13.4
22.5
11.7
4.7
4.9
7.0
3.0
0.9
0.5
4.1
2.1
1.6
2.4
CC Data
July 89
(pci/L)
122
57
161
32
19
80
41
333
401
792
1445
221
50
55
97
273
313
213
155
128
45
501
274
375
195
280
922
220
1414
Minimum = 1.2 15.2 4.0 0.5 19.0
Maximum = 70.1 38.2 392.0 22.5 1445.0
Average = IS.4 29.5 122.3 7.4 317.7
Notes For June subslab levels existing mitigation fans turned off
just prior to measurement.
For July subslab levels existing mitigation fans were off
for a period of 4 weeks before measurements.
B—41
-------
TABLE 7.5.1. SCHOOL L RADON MEASUREMENTS
CC
Numbers
Room
Description
(Room #5
Feb 89
CC Data
(pCi/L)
Feb 89
Follow-up
CC
(PCi/L)
June 89 •
CC Data
Levels
(pCi/L)
June 89
Subslab
(pCi/L)
1
Front Office
11.2
1.5
2
Principal
S.l
1.6
3
Clinic
10.5
1.5
4
Teachers' Lounge
17.1
1.4
5
Wash Boom
17.9
17
6
Library
17.6
21.4
336
7
Claaa Room #12
7.7
18.4
510
Class Room 12
282
Hall Rm 12
840
8
Class Room #14
13.1
15.6
588
9
Class Room #16
13.5
20
72
10
Class Room #18
11.3
17.5
126
Class Room #18
228
Hall Rm 18
516
11
Class Room #20
36.0 9.9
26. 5
210
N. Stor.
57-. 6
12
Class Room #19
24.3
11.9
234
13
Claaa Room #17
38.8 35.8
25.6
180
14
Class Room #15
40.3 31.5
20.6
228
15
Class Room #13
23.0
10.4
480
16
Class Room #11
32.1
19.9
300
Boiler Room
3.9
17
Class Room #1
4.3
60.7
2052
18
Class Room #3
2.9
56,2
2460
19
Class Room #5
8.3
33.7
654
20
Class Room #7
1.5
15.8
630
Class Room #7
408
Hall Rm 7
858
21
Class Room #9
2.9
10. 3
780
S. Storage
48
22
Class Room #10
11.3
9.2
210
23
Class Room #8
7.9
8.9
330
24
Class Room #6
1.9
5.5
1104
25
Class Room #4
5.7
26.9
1038
Closet Rm 4
1038
Hall Rm 4
1488
26
2
0.8
25.3
1488
Minimum =
0.8 9.9
1.4
48.0
Maximum =
40.3 35.8
60.7
2460.0
Average =
14.1 25.7
18.0
637.9
3te:
For June CC measurements
the utility tunnel
fans
were turned off.
B-42
-------
TfiBLE 7.6.1. School M Radon Measurements
Room
Feb 89
Feb 89
July 85
July 89
Descrip-
cc Data
Follow-up
CC Data
Subslab
cc
tion
CC
Levels
ambers
(Room #)
(pCi/L)
(pCl/L)
(PCi/L)
(pCi/L)
1
104
15.9
12-. 8
160
Clos.104
140
2
102
10.4
19 • 6
160
3
101
22.6
23.1
7.3
140
Hall 101
110
4
103
9.2
2.2
220
Hall 103
290
5
109
22.2
11.9
18.4
70
Lib Off
430
109ft,
100
6
111
5.8
5.7
7
113
3.6
5.9
8
115
3.4
5.4
9
117
3.4
5.3
10
118
5.1
0.5
11
116
3.9
2.4
12
114
6.4
3.1
13
112
6.3
3.2
14
110
49.0
20.8
120
15
10S
46.6
15.9
580
Book Rm
450
Hall Book Rm
500
16
106
42.6
. 32.7
11.5
17
107
54.4
36.1
23.1
780
Cloa.107
650
Hall Rml07
370
18
105
19.0
2.6
70
19
Ft.Off.
8.7
2.2
120
Hall Off
280
20
R. Off.
9.3
1.2
21
P.Off.
7.8
1.4
Aud.
100
Stage St
60
Minimum =
3.4
11.9
0.5
70.0
Maximum =
54.4
36.1
23.1
780.0
Average =
16.9
26.0
8.1
287 .0
B-43
-------
Table 8.3.1 Collocated Duplicate Charcoal Canister Results
(part 1 of 4)
Percent
Dup.
Std,
School
Can.
ZIP
Start
Stop
Level
Cnt.Err
Average
Dev.
cv
ID
No.
Code
Date
Date
(pCi/L)
<2 Sigma)
(pCi/L)(pCi/L)
Alabama
KWLAL10110
111724
35601
10/27/89
10/30/89
11. 5
2.2
KWLAL10110
111742
35601
10/27/89
10/30/89
11.9
2.1
11.7
0.2
1.7
KWLAL10120
111683
35601
10/27/89
10/30/89
3.8
4.2
KWLAL10120
111732
35601
10/27/89
10/30/89
3.6
4.9
3.7
0.1
2.7
KWLAL10130
111680
35601
10/27/89
10/30/89
2.1
6.4
KWLAL10130
111690
35601
10/27/89
10/30/89
2.0
7.0
2.1
0.0
2.4
KWLAL10208
111726
35601
10/27/89
10/30/89
0.9
12.7
KKLAL10208
111736
35601
10/27/89
10/30/89
0.9
12.9
0.9
0.0
0.0
KWIAL10214
111756
35601
10/27/89
10/30/89
4,9
3.8
KWLAL10214
111766
35601
10/27/89
10/30/89
5.1
3.9
5.0
0.1
2.0
KWIAL10219
111697
35601
10/27/89
10/30/89
2.7
5.1
KKLAL10219
111737
35601
10/27/89
10/30/89
2.8
5.4
¦ 2.8
0.0
1.8
KWLAL10233
111688
35601
10/27/89
10/30/89
1.1
10.3
KWLAL10233
111698
35601
10/27/89
10/30/89
5.8
3.3
3.5
2.4
CO
KWLAL10237
111693
35601
10/27/89
10/30/89
2.2
6,5
KWLAL10237
111713
35601
10/27/89
10/30/89
2.2
6,6
2.2
0.0
0.0
Maryland
KWLMD10105
111248
20715
11/17/89
11/20/89
5.3
5.3
KWLMD10105
111258
20715
11/17/89
11/20/89
4.8
4.8
5.1
0.3
5.0
KKLMD10115
111189
20715
11/17/89
11/20/89
5.2
4.8
KWLMD10115
111226
20715
11/17/89
11/20/89
5.5
5.1
5.4
0.2
2.8
KWLMD10126
111182
20715
11/17/89
11/20/89
3.7
6.9
KWLMD10126
111209
20715
11/17/89
11/20/89
3.1
7.0
3.4
0.3
8.8
KKLMD10105
111204
20715
12/01/89
12/04/89
3.0
6.2
KKLMD10105
111238
20715
12/01/89
12/04/89
3.1
5.9
3.1
0.0
1.6
KKLMD10111
111222
20715
12/01/89
12/04/89
4.4
4.8
KWLHD10111
111251
20715
12/01/89
12/04/89
3.7
4.6
4.1
0.4
8.6
KWLMD1011S
111183
20715
12/01/89
12/04/89
3.2
6.0
KKLMD10115
111272
20715
12/01/89
12/04/89
2.7
5.8
3.0
0.3
8.5
New York
KWLNY15110
111798
14779
12/08/89
12/10/89
42.9
1.2
KKLNYlSllO
111878
14779
12/08/89
12/10/89
50.1
1.2
46.5
3.6
7.7
XKLNY15220
111867
14779
12/08/89
12/10/89
1.5
10.5
KWLNY15220
111877
14779
12/08/89
12/10/89
1.6
10.1
1.6
0,1
3.2
XWLNY15235
111806
14779
12/08/89
12/10/89
23.6
1.8
KKLNY152 35
111823
14779
12/08/89
12/10/89
23.5
1.7
23.6
0.1
0.2
KKLNY15236
111789
14779
12/11/89
12/13/89
8.8
2.8
KWLNY15236
111863
14779
12/11/89
12/13/89
10.3
2.7
9.6
0.8
7.9
KWLNY15236
111844
14779
12/08/89
12/10/89
11.2
2.6
KWLNY15236
111845
14779
12/08/89
12/10/89
11.3
2.7
11.3
0.1
0.4
KKLNY15110
111089
14779
02/12/90
02/14/90
7.8
5.6
XWLNY15110
111118
14779
02/12/90
02/14/90
B.8
5.7
8.3
0.5
6.0
XWLNY15220
111105
14779
02/12/90
02/14/90
3.4
11.5
KWLNY15220
111103
14779
02/12/90
02/14/90
2.8
14.0
3.1
0.3
9.7
(continued)
B-44
-------
Table 8.3.1 Collocated Duplicate Charcoal Canister Results
(part 2 of 4)
Percent
Dtip.
Std.
School
Can.
ZIP
Start
Stop
Level
Cnt.Err
Average
Dev.
cv
ID
No.
Code
Date
Date
(pCi/L)
(2 Sigma;
(pCi/L)(pCi/L)
I*)
KWLNY15235
111082
14779
02/12/90
02/14/90
8.1
"5.3
KWLNY15235
111112
14779
02/12/90
02/14/90
8.8
5.6
8.5
0.3
4.1
KWLNY15110
111159
14779
03/13/90
03/15/90
5.3
8.2
KWLNY15110
111176
14779
03/13/90
03/15/90
5.6
8.7
5.5
0.1
2.8
KWLNY15220
111121
14779
03/13/90
03/15/90
1.7
24.8
KWLNY15220
111171
14779
03/13/90
03/15/90
1.0
41.0
1.4
0.4
25.9
KWLNY152 35
111157
14779
03/13/90
03/15/90
3.9
11.9
KWLNY15235
111156
14779
03/13/90
03/15/90
3.8
12.6
3.9
0.1
1.3
Tennessee
KHLTN20610
100780
37220
06/30/89
07/03/89
16.8
2.9
KWLTN20610
100800
37220
06/30/89
07/03/89
15.9
3.1
16.3
0.4
2.8
KWLTN20330
100831
37214
06/30/89
07/03/89
0.7
28.2
KWLTN20330
100851
37214
06/30/89
07/03/89
0.5
40. 5
0.6
0.1
16.7
KWLTN20338
100815
37214
06/30/89
07/03/89
7.5
4.8
KWLTN20338
100820
37214
06/30/89
07/03/89
7.7
4.6
7.6
0.1
1.3
KWLTN20349
100790
37214
06/30/89
07/03/89
1.0
19.8
KWLTN20349
100860
37214
06/30/89
07/03/89
0.7
33.0
0.9
0.2
17.6
KWLTN20310
103594
37214
06/30/89
07/03/89
3.5
7.8
KWLTN20310
103613
37214
06/30/89
07/03/89
3.5
8.1
3.5
0.0
0.0
KWLTN20320
100861
37214
06/30/89
07/03/89
2.9
8.5
KWLTN20320
100877
37214
06/30/89
07/03/89
3.0
7.9
3.0
0.0
1.7
KWLTN20323
100791
37214
06/30/89
07/03/89
1.6
12.2
KWLTN20323
100796
37214
06/30/89
07/03/89
1.4
17.5
1.5
0.1
6.7
KWLTN20130
98274
37211
06/30/89
07/03/89
8.0
3.6
KWLTN20130
98276
37211
06/30/89
07/03/89
7.6
3.7
7.8
0.2
2.6
KWLTN20910
100956
37217
06/09/89
06/12/89
9.5
4.0
KWLTN20910
100971
37217
06/09/89
06/12/89
8.4
3.8
9.0
0.6
6.1
KWLTN20920
100886
37217
06/09/89
OB/12/89
19. 6
2.5
KWLTN20920
100890
37217
06/09/89
06/12/89
19.4
2.5
19.5
0.1
0.5
KWLTN21110
103645
37210
06/30/89
07/03/89
0.5
KWLTN21110
103655
37210
06/30/89
07/03/89
0.5
0.5
0.0
0.0
KWLTN20910
103633
37217
06/30/89
07/03/89
11.3
3.6
KWLTN20910
103658
37217
06/30/89
07/03/89
11.5
3.5
11.4
0.1
0.9
KWLTN20920
103607
37217
06/30/89
07/03/89
35.9
1.9
KWLTN20920
103627
37217
06/30/89
07/03/89
33.5
1.8
34.7
1.2
3.5
KWLTN2 0620
100809
37220
06/30/89
07/03/89
6.9
4.7
KWLTN20620
100844
37220
06/30/89
07/03/89
6.8
4.6
6.9
0.0
0.7
KWLTN20628
100799
37220
06/30/89
07/03/89
9.8
4.2
KWLTN20628
100B34
37220
06/30/89
07/03/89
10.0
4.2
9.9
0.1
1.0
KWLTN20325
98692
37214
06/02/89
06/05/89
4.5
8.3
KWLTN2032 5
98723
37214
06/02/89
06/05/89
3.6
8.7
4.1
0.5
11.1
KWLTN20333
98743
37214
06/02/89
06/05/89
8.4
4.6
KWLTN20333
98752
37214
06/02/B9
06/05/89
8.5
4.6
8.5
0.1
0.6
(Continued)
B-45
-------
Table 8.3.1 collocated Duplicate Charcoal Canister Results
(part 3 of 4)
Percent
Dup.
Std.
School
Can.
ZIP
Start
Stop
Level
Cnt.Err
Average
Dev.
cv
ID
No.
Cod®
Date
Date
(pCi/L)
(2 Sigma)
(pCi/L)(pCi/L)
(%>
KWLTN20339
98701
37214
06/02/89
06/05/89
4.9
6.5
KWLTN20339
98763
37214
06/02/89
06/05/89
4.6
7.1
4.8
0.2
3.
KWLTN20312
98698
37214
06/02/89
06/05/89
28.2
2.4
KWLTN20312
98758
37214
06/02/89
06/05/89
31.5
2.4
29.9
1.6
5.
KWLTN20410
100937
37214
06/09/89
06/12/89
17.2
2.5
KWLTN20410
100963
37214
06/09/89
06/12/89
17.7
2.6
17.5
0.3
1.
KWLTN20320
98689
37214
06/09/89
06/12/89
5.2
5.1
KWLTN20320
98725
37214
06/09/89
06/12/89
5.4
4.8
5.3
0.1
1.
KWLTN20330
98720
37214
06/09/89
06/12/89
2.1
11.6
KWLTN20330
98734
37214
06/09/89
06/12/89
1.9
12.4
2.0
0.1
5.
KWLTN11740
98585
37207
06/09/89
06/12/89
3.6
7.4
KWLTN11740
98856
37207
06/09/89
06/12/89
4.3
7.6
4.0
0.4
8.
KWLTN20310
98755
37214
06/09/89
06/12/89
1.3
12.7
KWLTN20310
98759
37214
06/09/89
06/12/89
1.4
13.8
1.3
0.1
3.
KWLTN20317
98722
37214
06/02/89
06/06/89
3.5
8.9
KWLTN20317
98703
37214
06/02/89
06/06/89
3.2
9.7
3.4
0.1
4.
KWLTN20410
100937
37214
06/09/89
06/12/89
17.2
2.5
KWLTH20410
100963
37214
06/09/89
06/12/89
17.7
2.6
17.5
0.3
1.
KWLTN20420
100888
37214
06/09/89
06/12/89
15.8
2.6
KWLTN20420
100893
37214
06/09/89
06/12/89
15.8
2.6
15.8
0.0
0.
KWLTN20428
98714
37214
06/09/89
06/12/89
3.9
6.4
KWLTN20428
100913
37214
06/09/89
06/12/89
3.9
6.9
3.9
0.0
0.
KWLTN20610
100780
37220
06/30/89
07/03/89
16.8
2.9
KWLTN20610
100800
37220
06/30/89
07/03/89
15.9
3.1
16.3
0.4
2.
KWLTN20620
100809
37220
06/30/89
07/03/89
6.9
4.7
KHLTN20620
100844
37220
06/30/89
07/03/89
6.8
4.6
6.9
0.0
0.
KWLTN20628
100799
37220
06/30/89
07/03/89
9.8
4.2
KWLTN20628
100834
37220
06/30/89
07/03/89
10.0
4.2
9.9
0. 1
1.
KWLTN20110
100843
37211
06/30/89
07/03/89
18.6
2.7
KWLTN20110
100863
37211
06/30/89
07/03/89
19.6
2.6
19.1
0. 5
2.
KWLTN20120
98180
37211
06/30/89
07/03/89
4.9
6.1
KWLTN20120
98255
37211
06/30/89
07/03/89
4.8
6.2
4.9
0.0
1.
KWLTN20130
98274
37211
06/30/89
07/03/89
8.0
3.6
KWLTN20130
98276
37211
06/30/89
07/03/89
7.6
3.7
7.8
0.2
2.
KWLTN21110
103645
37210
06/30/89
07/03/89
0.5
KWLTN21110
103655
37210
06/30/89
07/03/89
0.5
0.5
0.0
0.
KWLTN21120
103651
37210
06/30/89
07/03/89
1.3
19.9
KWLTN21120
103673
37210
06/30/89
07/03/89
1.0
23.2
1.2
0. 1
13.
KWLTN20913
111607
37217
02/02/90
02/05/90
3.5
4.6
KWLTN20913
111647
37217
02/02/90
02/05/90
3.3
5.0
3.4
0.1
2.
KWLTN20919
111608
37217
02/02/90
02/05/90
1.0
10.6
KWLTN20919
111638
37217
02/02/90
02/05/90
1.3
10.1
1.2
0.1
13.
(Continued)
2
5
4
9
0
9
7
S
4
0
0
8
7
0
6
0
6
0
0
9
0
B-46
-------
Table 8.3.1 Collocated Duplicate Charcoal Canister Results
(part 4 of 4)
Percent
Dup.
Std.
School
Can.
ZIP
Start
Stop
Level
Cnt.Err
Average
Dev.
cv
ID
No.
Code
Date
Date
tpCi/L)
(2 Sigma)
4
pCi/L
= 0.2
1.6
High
= 3.6
11.1
Low
= 0.0
0.0
B-47
i
-------
Table 8.3.2 Average of Ml Collocated CC Results
Grouped By State
Average Maximum Minimum Average Maximum Minimum
State Std.Dev. Std.Dev. Std.Dev. CV(%) CV(%) CV(%)
AL
0.36
2. 35
0.00
9.85
68.12
0. 00
MD
0,23
0,35
0.05
5,89
8.82
1.64
NY
0.23
0.35
0.05
5,89
8.82
1.64
TN
0.22
1. 65
0.00
4 . 04
17.65
0.00
B-48
-------
the decision to install a suction point in this room. This was carried
out on January 4, 1989.
The building was retested using CCs over the weekend of January 13,
1990. The results of this series of tests are shown in Table 7.2.1 and
Figure 7.2.17. The levels obtained were satisfactory in all except Room
120 which measured 6.4 pCi/L and Room 104 which measured 5.5 pCi/L.
Consequently, it was decided that additional suction points would be
added to these two rooms. The second suction point in Room 120 was
located near the west wall of the room about equidistant from the north
and south walls. Depressurization for this added suction point was
obtained by installing a tee above the original suction point and
splitting the flow to both points. The additional suction point in Room
104 was Installed similarly, with the added point located adjacent to
the south wall of the room. These additional suction points were
installed on January 26, 1990, and were operational on January 27, 1990.
The final configuration of the mitigation systems in School I is shown
in Figure 7,2.18.
7.2.9 Final Radon Levels
All rooms of the building were again tested between February 2 and 5,
1990. The results of these tests are shown in Table 7*2.1 and Figure
7.2,19. The school average was 1.7 pCi/L with a low reading in Room 123
and the kitchen of 0.5 pCi/L and a high of 3.5 pCi/L in Room ill. since
all rooms were below the present EPA guideline of 4 pCi/L, no further
work is anticipated on this slab-on-grade portion of the building.
7.2.10 Estimated Cost
The estimated cost for materials and work hours expended to carry out
the initial mitigation at School I is shown in Table 7,2.6. Because of
the complexity of the additional diagnostics and mitigation work carried
out during January 1990, no cost estimates are included.
7.2.11 Summary
In summary, the diagnostics and mitigation research at School I has
illustrated that, even if the subslab communication is poor, an asd
system can be used to control the radon problem. The complexity of the
system increases as the communication under the slab decreases. It has
also raised the need for a better understanding between the levels of
radon gas under the slab and those in the room above. More study needs
to be carried out in this area. It was also seen that the type of
foundation used under the building affects the type of mitigation system
that can be used to control successfully the radon problem.
Schools H and I had widely different subslab communication resulting
from different subslab construction details and from differences in
aggregate* The poorer communication in School I was overcame by
increasing the number of suction points. The number used was based on
the communication determined using a vacuum cleaner communication test
59
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